WO2005032835A1 - Recording medium - Google Patents

Recording medium Download PDF

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Publication number
WO2005032835A1
WO2005032835A1 PCT/NL2004/000692 NL2004000692W WO2005032835A1 WO 2005032835 A1 WO2005032835 A1 WO 2005032835A1 NL 2004000692 W NL2004000692 W NL 2004000692W WO 2005032835 A1 WO2005032835 A1 WO 2005032835A1
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WIPO (PCT)
Prior art keywords
gelatin
medium according
ink
overlayer
modified
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PCT/NL2004/000692
Other languages
French (fr)
Inventor
Jacko Hessing
Huibert Albertus Van Boxtel
Akira Kase
Original Assignee
Fuji Photo Film B.V.
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Publication of WO2005032835A1 publication Critical patent/WO2005032835A1/en

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41MPRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52Macromolecular coatings
    • B41M5/5227Macromolecular coatings characterised by organic non-macromolecular additives, e.g. UV-absorbers, plasticisers, surfactants
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41MPRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52Macromolecular coatings
    • B41M5/5236Macromolecular coatings characterised by the use of natural gums, of proteins, e.g. gelatins, or of macromolecular carbohydrates, e.g. cellulose
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41MPRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00Duplicating or marking methods; Sheet materials for use therein
    • B41M5/50Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
    • B41M5/52Macromolecular coatings
    • B41M5/5254Macromolecular coatings characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers

Definitions

  • the present invention relates in general to a recording medium, in particular an ink -jet recording medium of photographic quality that has excellent ink absorption speed, good light fastness characteristics and a good image printing quality, as well as to methods for preparing such media.
  • ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium.
  • the ink droplets, or recording liquid generally comprise a recording agent, such as a dye, and a relatively large amount of solvent in order to prevent clogging of the nozzle.
  • the solvent, or carrier liquid typically is made up of water, and organic material such as monohydric alcohols and the like.
  • the recording medium should rapidly and durably absorb the dye from the ink.
  • dyes There are two types of dyes known in the art which may be applied in the ink formulation, i.e. pigment dye which is insoluble in the ink jet solvent and dyes that are soluble in the ink jet solvent.
  • US-A 4 926 190 proposes a specific type of benzotriazole that is particularly suitable for being used in the ink jet recording media to prevent light fading. It is preferable to add the compound in the surfacelayer of the coating.
  • EP-A 0738718 discloses another UV absorbing agent based on benzotriazole having an alpha-cumyl group attached to it that can be used in ink jet recording material.
  • the ink jet recording medium must be able to absorb the ink solvent quickly.
  • High quality image reproduction using ink -jet printing techniques requires a receptor medium, typically a sheet of paper or an opaque or transparent film, that readily absorbs ink droplets while preventing droplet diffusion or migration. Good absorption of ink encourages image drying while minimizing dye migration by which good sharpness of the recorded image is obtained.
  • a substrate with a porous layer which can act as the ink-receiving layer.
  • this known technique may give problems as to the gloss of the paper.
  • a gloss enhancing layer In this microporous type, the microporous film has as the primary function to absorb the ink solvent.
  • the typical microporous film suitable for this purpose is described inter alia in US-A-4 833 172, US-A-4 861 644 and US-A-5 326 391.
  • Another approach for producing ink-jet recording media with photographic quality and good drying properties is the so called "non- microporous film type", also known as “swellable type", as proposed in several patent publications such as DE-A 4 322 178, EP-A-806 299 and JP-A-22 760.
  • ink-jet recording medium at least one ink receptive layer is coated on a support such as a paper or a transparent film.
  • the ink receptive layer contains significant amounts of water soluble polymers, such as poly vinyl alcohol, gelatin etc.
  • water soluble polymers such as poly vinyl alcohol, gelatin etc.
  • Both types of ink jet recording media have their advantages and disadvantages.
  • the microporous type has generally a high absorbing capacity, while it has deficiencies in the gloss, the dye fading properties and image density.
  • the swellable type is better in dye fading and gloss properties, but it absorbs the ink solvent slowly. Attempts have been made to improve the dye fading properties, e.g. by adding light resisting imparting chemicals to microporous media as described in US 6 652 931.
  • the object of the present invention is thus to provide a recording medium having especially good drying and light fastness properties, said recording medium more in particular being suited to produce images of photographic quality. It is a further object of this invention, to provide a recording medium which gives no beading, has no matte appearance at high densities and has good bleeding properties It has been found that these objectives can be met by providing a recording medium comprising a support and an ink receiving layer adhered to said support, where the ink receiving layer is a multilayer comprising at least one underlayer and at least one overlayer in which the overlayer comprises at least one type of modified gelatin and wherein at least one layer of the multi layers comprises at least one type of hydrophobic UV absorbing agent.
  • the invention is directed to a recording medium comprising a support and an ink receiving layer adhered to said support, where the ink receiving layer is a multilayer comprising at least one underlayer and at least one overlayer in which the overlayer comprises at least one type of modified gelatin and wherein at least one layer of the multi layers comprises a hydrophobic UV absorbing agent.
  • This invention is also related to the manufacture of such a recording medium and to the use of this medium. According to this invention good properties of ink jet medium in terms of light fastness, beading, colour bleeding and ink absorption can be achieved by applying an ink receptive layer, which is a multilayer, wherein the composition of each layers is designed such that a specific function is accommodated in that layer.
  • This invention is characterized by the presence of at least one type of modified gelatin in the overlayer, and the presence of at least one UV absorbing agent in one of the layers.
  • the underlayer is a layer that is closer to the support than the overlayer.
  • the overlayer in the medium of the present invention is generally the toplayer, viz. the layer that is furthest away from the support and that is contacted first with the ink upon printing. It is possible to provide a further layer on the overlayer, which further layer then becomes the toplayer.
  • Both the overlayer and the underlayer of this invention may be a multilayer of sublayers. The total number of sublayers is not particularly limited and depends largely on the available technique for application of layers and the required ink receiving properties of the ink receiving layer.
  • the total number of sublayers may be from 2 to 25, more preferably from 3 to 17.
  • any kind of UV agent can be applied for the purpose of providing the ink jet media with good light fastness properties.
  • Depending on the chemical structure of the UV agent it has been found that some UV agents are more efficient to be used in this invention and some are less. It was found that in a multilayer coating, water soluble UV absorbing agents are generally less efficient compared to hydrophobic UV agents. Without wishing to be bound by theory, it is assumed that this is because water soluble UV agents have the ability to diffuse to all other layers.
  • hydrophobic UV agent refers to a limited solubility of the UV agent in water at 20°C and at atmospheric pressure.
  • Typical value for the solubility of a hydrophobic UV agent in water is less than 1 g/L.
  • the hydrophobic UV agents can be added as such to a solution of a hydrophilic polymer in water to give a dispersion.
  • the hydrophilic polymer is selected from the group of gelatin, pol vinylalcohol (PVA), polyvinylpyrollidone (PVP), carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC) and the like.
  • PVA pol vinylalcohol
  • PVP polyvinylpyrollidone
  • CMC carboxymethylcellulose
  • HEC hydroxyethylcellulose
  • the most suitable hydrophilic polymer is gelatin.
  • the gelatin can be any of modified or non-modified gelatins.
  • non-modified gelatins examples include alkali-treated gelatin (cattle bone or hide gelatin), acid-treated gelatin (pigskin, cattle/pig bone gelatin), or hydrolyzed gelatin.
  • modified gelatins examples include acetylated gelatin, phthalated gelatin, quaternary ammonium modified gelatin, et. cetera.
  • the gelatins can be used singly or in combination.
  • a dispersion is made using one of the techniques known in the art. These methods include methods using a high speed rotating disk, rotor stator methods, methods using any conventional colloid mill, a method using a homogeniser and the like.
  • surfactants suitable for the practice of this invention are for example: sulfosuccinic acid alkyl ester such as Aerosol OT, alkyl aryl sulfonates, potassium salts of alkyl naphthalene sulfonic acids, sodium dialkyl naphthalene sulfonate, sodium alkyl naphthalene sulfonate, sodium dodecylsulfate, sodium dodecylbenzenesulfonate, fatty acid esters of sorbitan, tetrasodium N-(l,2- dicarboxyethyl)-N-octyldecylsulfosuccinamate and the like.
  • surfactants can be used alone or as a mixture.
  • the quantity of the surfactant used or the mixture of surfactants most general is generally between 4 and 10 % of the hydrophobic UV agent amount.
  • the hydrophobic UV agent is added as an oil-in- water emulsion.
  • the steps for making the oil-in-water emulsion are: (1) dissolving the hydrophobic UV agent in a high boiling organic solvent in the presence or absence of a co-solvent; (2) dissolving the hydrophilic polymer in water; (3) emulsifying the UV agent solution into the hydrophilic polymer solution by vigorous stirring, by applying hig -pressure homogenisation, by treatment with ultrasonic frequencies, or any other method known in the art.
  • the high -boiling organic solvents of this invention preferably have a boiling point of not lower than 175 °C at normal pressure.
  • trialkyl phosphates and triaryl phosphates such as trihexyl, trioctyl, tridecyl, tris(butox eth l), tris(haloalkyl), trixylenyl and tricresyl phosphate, can be used for preparing oil-in-water emulsions.
  • phthalate esters, citric esters, benzoic esters, fatty acid esters and fatty acid amides, as well as hydrocarbons such as n-decane or n-dodecane can be used.
  • Organic solvents having a boiling point of not lower than about 30 °C, preferably not lower than about 50 °C, but not higher than about 160 °C can be used as co-solvents.
  • the co- solvents include ethyl acetate, butyl acetate, ethyl propionate, methyl ethylketone, cyclohexanone, 2-ethoxyetlryl acetate and the like.
  • the suitable hydrophilic polymer and surfactant needed to make a stable oil -in water emulsion can be selected from the groups mentioned before.
  • Preferable hydrophilic polymers are gelatine and the preferred surfactants are sodium dodecylbenzenesulfonate, Aerosol OT, and combination thereof.
  • the average particle size of the oil droplets of the oil-in-water emulsion is preferably smaller than 500 nanometer and more preferably smaller than 300 nanometer.
  • the under limit of the particle size is mainly determined by the used recipe and the mechanical forces used to make the oil-in-water emulsion.
  • the typical average size of the particle size is mostly from 50 to 300 nm.
  • the UV agent may be applied in any layer of the ink receptive layer, however it has been found that an optimum dye fading prevention can be achieved by applying the UV agent in the under layer that is directly adjacent to (viz. in contact with) the overlayer. In another embodiment, the UV agent may be further applied in several underlayers.
  • This embodiment is especially advantageous in case the support does not have sufficient capacity to absorb remaining UV light that penetrates the ink receptive layer.
  • the reflected UV light may than be absorbed by UV agents applied in the underlayer close to the substrate.
  • a hydrophobic UV agent it is also possible to apply water soluble UV agents in the above mentioned embodiments.
  • Suitable UV agents are selected from the group consisting of purine compounds, pyrimidine compounds, benzimidazole compounds, imidazolidine compounds, urazole compounds, pyrazole compounds, triazole compounds, benzotriazole compounds, tetrazole compounds, pyrazine compounds, cinnamate .compounds, aminobutadien compounds and mixtures thereof.
  • UV agent examples include those described in Research Disclosure RD24239, RD290119, RD30326, EP-A 0 673 783, GB-A 2088 777, EP-A 0955180, EP-A-0 738 718, US-A-4926190 and in Ullmann's Encyclopedia of Industrial Chemistry, 5 th completely revised edition 1992, volume 20, page 468-471.
  • Suitable UV absorbers are also compounds containing a triazine skeleton.
  • EP-A- 0711804 and DE-A- 19739797 are preferable.
  • Preferred UV agents are benzotriazole compounds, such as 2-(2- hydroxy-5'methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t- butylphenyl)benzotriazole, 2-(2'-hydiOxy-3',5'-di-t-butylpheny ⁇ )-5- chlorobenzotriazole , 2 - (2'-hy droxy- 5'-t-butylphenyl)benzotriazole , 2 -(2' - hydroxy-5'-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-sec-butyl-5'-t- butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-sec-butyl-5'-t-butylphenyi)-5- chlorobenzotriazole, 2-(2'-hydroxy-4'-n-hexyloxypheny
  • the UV agent may be added in the amount from 0.03 g/m 2 to 10 g/m 2 , preferable between 0.03 g/m 2 and 5 g/m 2 .
  • the overlayer of this invention comprises a modified gelatin, and may further comprise water insoluble particles inter alia to regulate the slip behaviour and optionally one or more water soluble polymers, surfactants and other additives to optimise the surface properties.
  • modified gelatin as tised herein, refers to gelatin compounds in which at least part of the NH 2 groups is chemically modified. A variety of modified gelatins can be used in the overlayer.
  • modified gelatins comprise an alkyl group (more preferably a Cs-C25-alkyl group), a fatty acid group (more preferably C5- C 25 -fatty acid group), or both.
  • the gelatins comprise a C - Cis-alkyl group, a C 7 -C ⁇ s-fatty acid group, or both.
  • Especially preferred gelatins of this type are succinic acid modified gelatins in which the succinic acid moiety contains an aliphatic chain from at least 5 to 25 carbon-atoms, where the chain can still be modified to a certain extend to adjust the water soluble properties or ink receptive properties.
  • Most preferred is the use of dodecenylsuccinic acid modified gelatin, in which at least 30% of the NH2 groups of the gelatin have been modified with said dodecenylsuccinic acid.
  • Another method for obtaining modified gelatin is described in EP-A- 0576911, where said gelatin is formed from gelatin containing pendant amine groups and pendant carboxylic groups wherein at least one amine group of said gelatin is modified to form an amide of the formula -NHCOR.
  • the process typically involves reaction of an amine group with an activated carboxyl, i.e. a reaction product of a carboxyl activating agent and carboxylic acid, i.e., RCOOH wherein R represents substituted or unsubstituted alkyl of 1-10 carbons, substituted or unsubstituted aryl of 6-14 carbons, or substituted or ⁇ nsubstituted arylalkyl of 7-20 carbons.
  • an activated carboxyl i.e. a reaction product of a carboxyl activating agent and carboxylic acid, i.e., RCOOH wherein R represents substituted or unsubstituted alkyl of 1-10 carbons, substituted or unsub
  • modified gelatins known in the common gelatin technology, such as phtalated gelatin and acetylated gelatins are also suitable to be used in this invention.
  • the modified gelatin can be used alone or in combination with another water soluble polymer.
  • these polymers include: fully hydrolysed or partially hydrolysed polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinylpyrolidone, any gelatin whether lime-processed or acid processed made from animal collagen, preferably gelatin made from pig skin, cow skin or cow bone, polyethylene oxide, poly aery lamide, and the like.
  • the modified gelatin is preferably applied in the overlayer in an amount ranging from 0.3 to 5 g/m 2 and most preferably from 0.5 to 3 g/m 2 .
  • a suitable amount of the water soluble polymer in the mixture is varying between 0 and 75 wt% of the amount of the modified gelatin. In case said water soluble polymer amount is higher than 75 wt%, the advantages of the modified gelatin may become less pronounced.
  • the mere application of the modified gelatin or mix of modified gelatin and water soluble polymers improves the characteristics with respect to drying and finger smearing properties.
  • a further improvement of above mentioned properties can be obtained by including in the overlayer a fluorosurfactant in the amount between 2.5 mg/m 2 and 250 mg/m 2 .
  • fluorosurfactant refers to surfactants (viz. molecules having a hydrophilic and a hydrophobic part) that contain fluorocarbon or a combination of fluorocarbon and hydrocarbon as the hydrophobic part. Suitable fluorosurfactants may be anionic, non-ionic or cationic.
  • fluorosurfactants are: fluoro C2-C20 alkylcarboxylic acids and salts thereof, disodium N-perfluorooctanesulfonyl glutamate, sodium 3-(fluoro-C6-Cn alkyloxy)-l-C3-C alkyl sulfonates, sodium 3-(omega -fluoro-Ce-Cs alkanoyl-N-ethylamino)-l-propane sulfonates, N-[3- (perfluorooctanesulfonamide)-propyl]-N,N-dimethyl-N-carboxymethylene ammonium betaine, perfluoro alkyl carboxylic acids (e.g.
  • perfluoro C7-C13 alkyl carboxylic acids and salts thereof perfluorooctane sulfonic acid diethanolamide, Li, K and Na perfluoro C4-C12 alkyl sulfonates, Li, K and Na N-perfluoro C4-C13 alkane sulfonyl — N- alkyl glycine, fluorosurfactants commercially available under the name Zonyl ® (produced by E.I.
  • the fluorosurfactant is chosen from Li, K and Na N-perfluoro C4-C13 alkane sulfonyl -N- alkyl glycine, 2-sulfo-l,4.bis(fluoroalkyl)butanedioate, 1,4-bis (fluoroalkyl)-2-[2-(N,N,N- trialkylammonium alkyl amino] butanedioate, perfluoroalkyl subsitituted carboxyhc acids commercially available under the name Lodyne ® (produced by Ciba Specialty Chemicals Corp.) and fluorosurfactants commercially available under the name Zonyl ® (produced by E.I.
  • the amount of matting agent is from 0.01 to 1 g/m 2 , preferably from 0.02 to 0.5 g/m 2 .
  • the matting agent can be defined as particles of inorganic or organic materials capable of being dispersed in a hydrophilic organic colloid.
  • the inorganic matting agents include oxides such as silicon oxide, titanium oxide, magnesium oxide and aluminium oxide, alkali earth metal salts such as barium sulphate, calcium carbonate, and magnesium sulphate, and glass particles. Besides these substances one may select inorganic matting agents which are disclosed in West German Patent No. 2,529,321, British Patent Nos. 760,775 and 1,260,772, U.S. Pat. Nos.
  • the organic matting agents include starch, cellulose esters such as cellulose acetate propionate, cellulose ethers such as ethyl cellulose, and synthetic resins.
  • the synthetic resins are water insoluble or sparingly soluble polymers which include a polymer of an alkyl(meth) aery late, an alkoxyalkyl(meth) aery late, a glycidyl(meth)acrylate, a (meth)acrylamide, a vinyl ester such as vinyl acetate, acrylonitrile, an olefin such as ethylene, or styrene and a copolymer of the above described monomer with other monomers such as acrylic acid, methacrylic acid, alpha, beta -unsaturated dicarboxylic acid, hydroxyalkyl(meth)acrylate, sulfo alky l(meth) aery late and styrene sulfonic acid.
  • a benzoguanamin-formaldehyde resin an epoxy resin, nylon, polycarbonates, phenol resins, polyvinyl carbazol or polyvinylidene chloride can be used.
  • organic matting agents which are disclosed in British Patent No. 1,055,713, U.S. Pat. Nos. 1,939,213, 2,221,873, 2,268,662, 2,322,037, 2,376,005, 2,391,181, 2,701,245, 2,992,101, 3,079,257, 3,262,782, 3,443,946, 3, 516,832, 3,539,344,554, 3,591,379, 3,754,924 and 3,767,448, Japanese Patent O.P.I. Publication Nos.
  • the overlayer may optionally include thickener agents, biocides crosslinking agents and further various additives such as colorants, colored pigments, pigment dispersants, mold lubricants, permeating agents, fixing agents for ink dyes, anti-oxidants, dispersing agents, anti-foaming agents, leveling agents, fluidity improving agents, antiseptic agents, optical brightening agents, viscosity stabilizing and/or enhancing agents, pH adjusting agents, anti-mildew agents, anti-fungal agents, agents for moisture- proofing, agents for increasing the stiffness of wet paper, agents for increasing the stiffness of dry paper and anti-static agents.
  • thickener agents biocides crosslinking agents and further various additives such as colorants, colored pigments, pigment dispersants, mold lubricants, permeating agents, fixing agents for ink dyes, anti-oxidants, dispersing agents, anti-foaming agents, leveling agents, fluidity improving agents, antiseptic agents, optical brightening agents, viscosity stabil
  • the above-mentioned various additives can be added ordinarily in an amount, such that the total additives content ranges from 0 to 10 weight% based on the solid content of the overlayer composition.
  • the beneficial effects of the modified gelatin and the fluorosurfactant is generated by applying these compounds in separate overlayers, meaning, that also the overlayer is a multilayer.
  • the fluorosurfactant in a coating layer farthest away from the substrate and the modified gelatin applied under this layer.
  • the underlayer can be a multilayer of sublayers.
  • the underlayer preferably comprises gelatin and a hydrophilic polymer, a UN compound (as mentioned before) and optionally additives to adjust the physical properties.
  • This swellable underlayer determines mainly the physical properties like water uptake, drying speed, brittleness and curl. It was found that in case the underlayer is a multilayer it is beneficial to apply different concentrations of gelatin and water soluble polymer in the sublayers of the underlayer. A lower concentration of gelatin and water soluble polymer in the sublayer closest to the support enables a lower viscosity of the mixture which improves the coatability and allows higher coating speeds.
  • an adhesion promoting layer is applied between the support and the underlayer to enhance the adhesion of the coated layers onto the support. This adhesion promoting layer may be coated in a separate step or simultaneously with the receiving layers.
  • gelatins there is a variety of gelatins, both non-modified as well as modified gelatins which can be used in the underlayer.
  • non-modified gelatins are alkali-treated gelatin (cattle bone or hide gelatin), acid -treated gelatin (pigskin, cattle/pig bone gelatin), or hydrolyzed gelatin.
  • modified gelatins are acetylated gelatin, phthalated gelatin, quaternary ammonium modified gelatin, et cetera. These gelatins can be used singly or in combination for forming one or more of the layers of the underlayer. Acid and alkali treated gelatins are preferred.
  • Water soluble polymers suitable to be mixed with the (modified) gelatin include polyvinyl alcohol- (PVA-)based polymers, such as fully hydrolysed or partially hydrolysed polyvinyl alcohol (PVA), carboxylated polyvinyl alcohol, copolymers and terpolymers of PVA with other polymers, watersoluble cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, casein, gum arabic, polyacrylic acid and its copolymers or terpolymers, polymethylacryhc acid and its copolymers or terpolymers, and any other polymers, which contain onomers of carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and crotonic acid, polyvinylpyrolidone (PVP), polyethylene oxide, poly aery lamide, 2-pyrrolidone and its derivatives such as N (2 -hydroxyethyl) - 2-pyrrolidone and
  • Water soluble polymers can have very limited compatibility with gelatin. These polymers include fully hydrolyzed or partially hydrolyzed polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyethylene oxide, polyacrylamide , and the like.
  • a solution of gelatin in water is mixed with a solution in water of one of the above described polymers, micro or macro phase separation occurs in solution which persists in the dried coating.
  • the dried coating exhibits high haze, low transparency, and low gloss.
  • a homogeneous gelatin -PEO mixture i.e. a mixture where no phase separation occurs, may be obtained by adjusting the pH of the mixture.
  • the best way is to follow the practical approach by making the required mixture of gelatin and water soluble polymer in water and adding alkali or acid until a homogeneous solution is obtained.
  • the suitable pH range mainly depends on the gelatin type used and type of the water soluble polymer.
  • gelatin/PEO ratios (wt./wt.) in the layer nearest to the overlayer preferably vary between 1/1 to 8/1 and the gelatin/PEO ratios (wt./wt.) in the layers nearest to the support preferably vary between 1/1 and 12/1, preferably with the condition, that the gelatin/PEO ratio of the layer adjacent to the overlayer is always lower, than the ratio of the other gelatin - PEO layers.
  • gelatin/PEO ratios (wt./wt.) in the layer nearest to the overlayer preferably vary between 1/1 to 8/1 and the gelatin/PEO ratios (wt./wt.) in the layers nearest to the support preferably vary between 1/1 and 12/1, preferably with the condition, that the gelatin/PEO ratio of the layer adjacent to the overlayer is always lower, than the ratio of the other gelatin - PEO layers.
  • a gradient for the gelatin/PEO ratio meaning, that the gelatin/PEO ratio is lowest in the layer adjacent to the overlayer and said ratio
  • the homogeneous gelatin-PEO solution of the underlayer, which is applied to the substrate has a gelatin concentration between 5 and 20 wt.%.
  • PEO water soluble polymers having a limited compatibility with each other. It has been found by the present inventors that one may substitute the PEO with other water soluble polymers mentioned above such as PVP or PVA or a mixture between two or more water soluble polymers s ch as PEO and PVP.
  • the ratio between the gelatin and said water soluble polymer(s) are preferably in the same ranges as described above for gelatin-PEO system. Good results are obtained with PVA-based polymers.
  • PVA-based polymers In general a large variety of PVA-based polymers can be used, but the preferred PVA-based polymers are those which have been modified to give a good miscibility with aqueous gelatin solutions. These modifications are such, that in the PVA-based polymer back bone groups are introduced which provide a hydrogen bonding site, an ionic bonding site, carboxylic groups, sulphonyl groups, amide groups and the like, thus providing a modified PVA-based polymer.
  • a modified PVA- based polymer giving very good results is a poly (vinyl alcohol) -co-poly (n- vinyl formamide) copolymer (PVA-NVF).
  • Very suitable PVA-NVF copolymers for use with the present invention are the copolymers described in WO-A-03/054029, which have the general formula I:
  • Ri, and R3 are independently H, 3-propionic acid or C I -CG alkyl ester thereof, or is 2-methyl-3-propionic acid or Ci-Ce alkyl ester thereof; and R2 and R 4 are independently H or CI-CG alkyl.
  • the water soluble polymer is preferably applied for the underlayer i an amount ranging from 0.5 to 15 g/m 2 , more preferably from 1.0 to 8.0 g/m 2 .
  • the homogeneous aqueous solution of the underlayer may further contain the following ingredients in order to improve the ink receiving layer properties with respect to ink receptivity and the physical strength of the layer: - One or more plasticizers, such as ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, glycerol monomethylether, glycerol monochlorohydrin, ethylene carbonate, propylene carbonate, tetrachlorophthahc anhydride, tetrabromophthalic anhydride, urea phosphate, triphenylphosphate, glycerolmonostearate, propylene glycol monostearate, tetramethylene sulfone, N-methyl-2-pyrrolidone, N-vinyl-2-pyr
  • fillers are not essential for this invention. Nevertheless, some of the conventional fillers may be used, some of which fillers may impart further porosity. Both organic and inorganic particles can be used as fillers.
  • Useful filler examples are represented by silica (colloidal silica), alumina or alumina hydrate (aluminazol, colloidal alumina, a cat ion aluminum oxide or its hydrate and pseudo-boehmite), a surface-processed cat ion colloidal silica, aluminum silicate, magnesium silicate, magnesium carbonate, titanium dioxide, zinc oxide, calcium carbonate, kaolin, talc, clay, zinc carbonate, satin white, diatomaceous earth, synthetic amorphous silica, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide and synthetic mica.
  • organic fillers are represented by polystyrene, polymethacrylate, polymethyl-methacrylate, elastomers, ethylene -vinyl acetate copolymers, polyesters, polyester-copolymers, polyacrylates, polyvinylethers, polyamides, polyolefins, polysilicones, guanamine resins, polytetrafluoroethylene, elastomeric styrene-butadiene rubber (SBR), urea resins, urea-formalin resins.
  • Such organic and inorganic fillers may be used alone or in combination.
  • One or more mordants Mordants may be incorporated in the ink- receptive layer of the present invention.
  • mordants are represented by cationic compounds, monomeric or polymeric, capable of complexing with the dyes used in the ink compositions.
  • Useful examples of such mordants include quaternary ammonium block copolymers.
  • Other suitable mordants comprise diamino alkanes, ammonium quaternary salts and quaternary acrylic copolymer latexes.
  • fluoro compounds such as tetra ammonium fluoride hydrate, 2,2,2-trifluoroethylamine hydrochloride, 1- (alpha, alpha, alpha -trifluoro-m-tolyl) piperazine hydrochloride, 4-bromo- alpha, alpha, alpha -trifluoro-o-toluidine hydrochloride, difluorophenylhydrazine hydrochloride, 4-fluorobenzylamine hydrochloride, 4- fluoro- alpha, alpha -dimethylphenethylamine hydrochloride, 2- fluoroethylaminehydrochloride, 2 -fluoro- 1-methyl pyridinium-toluene sulfonate, 4-fluorophenethylamine hydrochloride, fluorophenylhydrazine hydrochloride, l-(2-fluorophenyl) piperazine monohydrochloride, 1-fluor
  • pigments white pigments such as titanium oxide, zinc oxide, talc, calcium carbonate and the like; blue pigments or dyes such as cobalt blue, ultramarine or phthalocyanine blue; magenta pigments or dyes such as cobalt violet, fast violet or manganese violet; • biocides; • pH controllers; • preservatives; • viscosity modifiers; • dispersing agents; • brightening agents; • dye fading preventing agents; • antistatic agents; and/or • anionic, cationic, non-ionic, and/or amphoteric surfactants, typically used in amounts ranging from 0.1 to 1000 mg/m 2 , preferably from 0.5 to 100 mg/m 2 .
  • additives may be selected from known compounds and materials in accordance with the objects to be achieved.
  • the above-mentioned additives may be added in a range of 0 to 30% by weight, based on the solid content of the water soluble polymers and/or gelatin in the underlayer.
  • the particle sizes of the non water-soluble particulate additives should not be too high, since otherwise a negative influence on the resulting surface will be obtained.
  • the used particle size should therefore preferably be less than 10 ⁇ m, more preferably 7 ⁇ m or less.
  • the particle size is preferably above 0.1 ⁇ m, more preferably about 1 ⁇ m or more for handling purposes.
  • the gelatin is preferably used in a total amount of from 1 to 30 g/m 2 , and more preferably from 2 to 20 g/m 2 .
  • the amount of hydrophilic polymer used in a certain formulation is typically in the range from 100 mg/m 2 to 30 g/m 2 and more preferably between 200 mg/m 2 and 20 g/m 2 .
  • each layer comprises an amount of gelatin ranging from 0.5 to 10 g/m 2 .
  • the gelatin in the image -recording elements of the present invention can be cross-linked in order to impart mechanical strength to the layer. This can be done by any cross-linking agent known in the art.
  • cross-linking agents also known as hardening agents.
  • the hardener include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedion, bis (2-chloroethylurea), 2-hydroxy-4, 6- dichloro-l,3,5-triazine, reactive halogen-containing compounds disclosed in US-A-3 288 775, carbamoyl pyridinium compounds in which the pyridine ring carries a sulphate or an alkyl sulphate group disclosed in US-A-4 063 952 and US-A-5 529 892, divinylsulfones, and the like.
  • the amount of hardener used preferably ranges from 0.1 to 10 g, and more preferably from 0.1 to 7 g based on 100 g of gelatin contained in the ink-receiving layer.
  • a cross-linking agent selected from borax, glyoxal, dicarboxylic acids and the like.
  • the process for producing a recording medium comprises the steps of: preparation of at least one aqueous mixture comprising at least a modified gelatin for the overlayer and preparation of one or more homogeneous aqueous mixtures for one or more underlayers.
  • the process further includes the preparation of an oil-in water emulsion comprising one or more hydrophobic UV agents dissolved in a high boiling organic solvent and optionally in the presence of a low boiling organic co-solvent, or alternatively the preparation of a dispersion comprising one or more hydrophobic UV agents in a hydrophilic solvent, followed by mixing said oil-in-water emulsion or said dispersion with at least one of said mixtures for the underlayers or the overlayer to give a homogenous emulsion.
  • the resulting formulations for the overlayer(s) and underlayer or underlayers can be coated consecutively or simultaneously to a support by any method known in the art.
  • the coating methods are for example, a curtain coating, an extrusion coating, an air-knife coating, a slide coating, a roll coating method, reverse roll coating, dip coating processes and a rod bar coating.
  • the support used in this invention may suitably be selected from a paper, a photographic base paper, a paper coated on both sides with a polymer layer, pigment coated paper, a synthetic paper or a plastic film in which the top and back coatings are balanced in order to minimise the curl behaviour.
  • the backside coating comprises gelatin or a water soluble polymer in an amount ranging preferably from 1 to 20 g/m 2 , more preferably from 4 to 15 g/m 2 . The optimum amount of the backside coating depends on the type of gelatin, the.
  • the preferred polymer for the backside coating is gelatin.
  • An important characteristic of the inkjet recording medium is the gloss. It has been found that the gloss of the medium can be improved by selecting the appropriate surface roughness of the used support. It was found, that providing a support having a surface roughness characterised by the value Ra being less than 1.0 ⁇ m, preferably below 0.8 ⁇ m a very glossy medium can be obtained. A low value of the Ra indicates a smooth surface.
  • the Ra is measured according to DIN 4776; software package version 1.62 with the following settings:
  • the base paper to be used as the support for the present invention is selected from materials conventionally used in high quality printing paper. Generally it is based on natural wood pulp and if desired, a filler such as talc, calcium carbonate, TiO 2 , BaS0 4 , and the like can be added. Generally the paper also contains internal sizing agents, such as alkyl ketene dimer, higher fatty acids, paraffin wax, alkenylsuccinic acid, epichlorhydrin fatty acid amid and the like.
  • the paper may contain wet and dry strength agents such as a polyamine, a poly-amide, poly aery lamide, poly-epichlorhydrin or starch and the like. Further additives in the paper can be fixing agents, such as aluminium sulphate, starch, cationic polymers and the like.
  • the Ra value for a normal grade base paper is well above 1.0 ⁇ m typically above 1.3 ⁇ m. In order to obtain a base paper with a Ra value below 1.0 ⁇ m such a normal grade base paper can be coated with a pigment. Any pigment can be used.
  • pigments are calcium-carbonate, TiO 2 , BaSO4, clay, such as kaolin, styrene- acrylic copolymer, Mg-Al-silicate, and the like or combinations thereof.
  • the amount being between 0.5 and 35.0 g/m 2 more preferably between 0.5 and 20.0 g/m 2 .
  • This pigmented coating can be applied as a pigment slurry in water together with a suitable binders like styrene-butadiene latex, methyl methacrylate-butadiene latex, polyvinyl alcohol, modified starch, polyacrylate latex or combinations thereof, by any technique known in the art, like dip coating, roll coating, blade coating or bar coating.
  • the pigment coated base paper may optionally be calendered.
  • the surface roughness can be influenced by the kind of pigment used and by a combination of pigment and calendering.
  • the base pigment coated paper substrate has preferably a surface roughness between 0.4 and 0.8 ⁇ m. If the surface roughness is further reduced by super calendaring to values below 0.4 ⁇ m the thickness and stiffness values will generally become below an acceptable level.
  • the ink receiving multilayer of the present invention can be directly applied to the pigment coated base paper.
  • the pigment coated base paper having a pigmented top side and a back-side is provided on both sides with a polymer resin through high temperature co-extrusion giving a laminated pigment coated base paper.
  • the preferred polymers used are poly olefins, particularly polyethylene.
  • the polymer resin of the top side comprises compounds such as an opacifying white pigment e.g. TiO 2 (anatase or rutile), ZnO or ZnS, dyes, coloured pigments, including blueing agents, like e.g. ultramarine or cobalt blue, adhesion promoters, optical brighteners, antioxidant and the like to improve the whiteness of the laminated pigment coated base paper.
  • an opacifying white pigment e.g. TiO 2 (anatase or rutile), ZnO or ZnS, dyes, coloured pigments, including blueing agents, like e.g. ultramarine or cobalt blue, adhesion promoters, optical brighteners, antioxidant and the like.
  • the total weight of the laminated pigment coated base paper is preferably between 80 and 350 g/m 2 .
  • the laminated pigment coated base paper shows a very good smoothness, which after applying the ink receiving layer of the present invention results in a recording medium with excellent gloss.
  • the material of the plastic film are polyolefins such as polyethylene and polypropylene, vinyl copolymers such as polyvinyl acetate, polyvinyl chloride and polystyrene, polyamide such as 6, 6 -nylon and 6-nylon, polyesters such as polyethylene terephthalate, polyethylene -2 and 6- naphthalate and polycarbonate, and cellulose acetates such as cellulose triacetate and cellulose diacetate.
  • the support may be subjected to a corona treatment in order to improve the adhesion between the support and the ink receiving layer. Also other techniques, like plasma treatment can be used to improve the adhesion.
  • the swellable ink-receiving layer has a dry thickness from 1 to 50 micrometers, preferably from 5 to 25 and more preferably between 8 and 20 micrometers. If the thickness of said ink receiving layer is less than 1 micrometer, adequate absorption of the solvent will not be obtained. If, on the other hand, the thickness of said ink receiving layer exceeds 50 micrometers, no further increase in solvent absorptivity will be gained.
  • the media of the present invention can be used in any printing application where photographic quality is required.
  • the high quality recording media of the present invention are not limited to inkjet recording media (viz. media suitable to be printed on using inkjet printers), but that it is within the scope of the present invention to provide recording media that are suitable for creating high quality images by using other techniques as well, such as Giclee printing, colour copying, screen printing, gravure, dye -sublimation, flexography, and the like.
  • the media of the present invention show excellent behavior with respect to properties as lightfastness, coloration, beading and glossiness, as is illustrated in more detail by the non -limiting examples given below.
  • the lightfastness of the media according to the present invention which may be expressed as the remaining color-density percentage after exposing a sample for 144 hrs using a xenon light (85 000 lx) in an Atlas Wether-O -Meter C I 35A (manufactured by Atlas (Illinois, U.S.A.)), may be 80% or more (density measured using a reflection densitometer (X-Rite 310TR)).
  • the media of the present invention may have an excellent coloration behavior, the coloration of the media upon storage at typical storage conditions being minimal. The coloration (viz.
  • the "yellowing" of the white parts of the media of the present invention upon aging may be assessed using a protocol in which L, a*, b* values are measured by a spectrophotometer (e.g. a MINOLTA CM-1000R).
  • the media of the present invention may have a ⁇ E (whiteness difference, expressed as b* values measured on a spectrophotometer, before and after aging) value after two weeks of storage at 50°C and 40% relative humidity of less than 5, preferably 2 or less.
  • ⁇ E whiteness difference, expressed as b* values measured on a spectrophotometer, before and after aging
  • Examples A Preparation of solution 'A' of the ink receiving layer.
  • Solution 'C of the ink receiving layer Preparation of solution 'C of the ink receiving layer.
  • Solution 'O was prepared in the same way as solution 'B', except that PEO was replaced by polyvinyl pyrollidone (PVP) having a molecular weight of about 30 000 Daltons (ICN Biochemicals).
  • PVP polyvinyl pyrollidone
  • E Preparation of an aqueous UV absorbing agent solution. 105 gram of benzophenon type UV absorber (Lowilite 20S, Great Lakes, USA) was dissolved at room temperature in 895 g of water containing 10 weight % lime processed gelatin. F. Schematic drawing and definition of the layer structure: Structure consisting of at least two underlayers and one overlayer
  • the underlayers and overlayer containing the solutions mentioned above were fed into a slide coating machine, commonly known in the photographic industry, and coated onto a photographic grade paper having polyethylene laminated at both sides.
  • the flow of the underlayers and that of the overlayer were selected such that, after drying, a total solid content of the underlayers (gelatine + other water soluble polymer) between 8 to 25 g/m 2 was obtained and a total solid content of the overlayer between 0.5 and 5 g/m 2 .
  • the coated material was chilled at a temperature of ca. 12°C to set the gelatin and then dried with dry air at a maximum temperature of 40°C.
  • the overlayer contained a mixture of 100 g of oil in water emulsion - D and 900 g of solution-A and the flow of the overlayer was 40 cc/m 2 .
  • the underlayer-2 contained a mixture of 50 g of solution-B and 50 g of solution C. The flow of underlayer-2 was 100 cc/m 2 .
  • the underlayer- 1 contained only solution C and the flow was adjusted at 50 cc/m 2 .
  • Inventive example #2 The sample was prepared in the same way as example 1, except for the composition of the overlayer and the underlayer-2.
  • the overlayer contained only solution-A, while the underlayer 2 contained a mixture of 40 g of oil in water emulsion-D, 480 g of solution-B and 480 g of solution-C.
  • the mixture was coated at flow of 100 cc/m 2 .
  • Inventive example #3 The sample was prepared in the same way as example 1, except for the overlayer and the underlayer- 1.
  • the overlayer contained solution-A only, while the underlayer-1 contained a mixture of 40 g of oil in water emulsion-D and 960 g of solution-C.
  • the flow of overlayer was kept at 40 cc/m2, while that for the underlayer-1 was adjusted to 100 cc/m 2 .
  • Inventive example #4 The sample was prepared in the same way as example 2, except for the composition of underlayer-2.
  • the underlayer 2 contained a mixture of 40 g of benzophenon solution E, 480 g of solution-B and 480 g of solution-C.
  • Comparative example #5 The comparative example 5 was prepared in the same way as the inventive example 1 except for the composition of the overlayer.
  • the overlayer contained only solution-A. In this example there is no UV agent present in the ink receiving layer.
  • Comparative example #6 The sample was prepared in the same way as example 2, except for the overlayer. In this comparative example 6 the overlayer which contained solution-A was not coated. In order to keep the total thickness, after drying, the same as in example 2, the flow of underlayer-2 was set to 123 cc/m 2 .
  • Comparable example #7 The sample was prepared in the same way as example 4, except for the overlayer. In this comparative example 7 the overlayer which contained a solution-A, was not coated. In order to keep the total thickness, after drying, the same as in example 4, the flow of underlayer-2 was set to 123 cc/m 2 .
  • Light fastness is one of the factors that determines the dye stability during the. display or storage at light condition.
  • a sample exposed for 144 hrs using a xenon light 85 000 lx
  • Atlas Wether-O-Meter C I 35A (manufactured by Atlas (Illinois, U.S.A.)).
  • the image density of the colors on the printed area was measured before and after the xenon irradiation by a reflection densitometer (X-Rite 310TR) and expressed as the remaining color-density percentage.
  • the following classification has been defined: O: more than 80% remaining density ⁇ : 80-60% remaining density
  • X less than 60% remaining
  • Beading behaviour As set out hereinabove, beading is defined as the phenomenon that large ink dots that become visible on the printed image. The following classification has been defined: O: no beading is observed
  • UV-1 UV-2:
  • UV-3 UV-4:

Abstract

The present invention relates to a recording medium, in particular an ink-jet recording medium of photographic quality that has excellent ink absorption speed, good light fastness characteristic and a good image printing quality. According to the present invention an ink-jet recording medium is provided, comprising a support to which at least an underlayer and an overlayer is supplied in which the overlayer contains at least one type of modified gelatin and wherein at least one layer of said multi layers comprises at least one type of UV absorbing agent. The present invention is further directed to methods for obtaining and using such a medium.

Description

Title: Recording medium
Field of the invention The present invention relates in general to a recording medium, in particular an ink -jet recording medium of photographic quality that has excellent ink absorption speed, good light fastness characteristics and a good image printing quality, as well as to methods for preparing such media.
Background of the invention In a typical ink -jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye, and a relatively large amount of solvent in order to prevent clogging of the nozzle. The solvent, or carrier liquid, typically is made up of water, and organic material such as monohydric alcohols and the like. The recording medium should rapidly and durably absorb the dye from the ink. There are two types of dyes known in the art which may be applied in the ink formulation, i.e. pigment dye which is insoluble in the ink jet solvent and dyes that are soluble in the ink jet solvent. Because of the fineness of the nozzles, pigment dyes are hardly used. Predominantly dyes which are fully dissolved in the ink jet solvent are used nowadays. However, these dyes generally have a lower light fastness than the dyes based on colored pigments. Consequently, recordings made by ink -jet printing using organic dyes may suffer from a limited storage life in the presence of light. In case of prolonged storage in light, they start to fade or to discolor. In order to solve this problem, many attempt has been done to add ultraviolet (UV) absorber in the ink formulation and/or in the recording material. GB-A 2 088 777 propose to add light stabilizer of phenols type in combination with UV absorbers of benzotriazole type to the recording material. US-A 4 926 190 proposes a specific type of benzotriazole that is particularly suitable for being used in the ink jet recording media to prevent light fading. It is preferable to add the compound in the surfacelayer of the coating. EP-A 0738718 discloses another UV absorbing agent based on benzotriazole having an alpha-cumyl group attached to it that can be used in ink jet recording material. Although the application of these known UV-absorbers in ink -jet recording media may provide improvements, there are also certain disadvantages involved in their application. One of the problems encountered is that the UV-absorbers tend to diffuse after coating, in particular in the presence of moisture. Further problems include re -crystallization after humidity cycle storage. As a result, known UV absorbers often do not work as designed or even may cause defects on the ink jet paper surface. Besides the above mentioned light fastness properties, the ink jet recording medium must be able to absorb the ink solvent quickly. High quality image reproduction using ink -jet printing techniques requires a receptor medium, typically a sheet of paper or an opaque or transparent film, that readily absorbs ink droplets while preventing droplet diffusion or migration. Good absorption of ink encourages image drying while minimizing dye migration by which good sharpness of the recorded image is obtained. There are in general two approaches for producing ink -jet recording media with photographic quality and good drying properties. One known approach is to provide a substrate with a porous layer, which can act as the ink-receiving layer. However, this known technique may give problems as to the gloss of the paper. In a specific embodiment there is provided on top of the porous layer a gloss enhancing layer. In this microporous type, the microporous film has as the primary function to absorb the ink solvent. The typical microporous film suitable for this purpose is described inter alia in US-A-4 833 172, US-A-4 861 644 and US-A-5 326 391. Another approach for producing ink-jet recording media with photographic quality and good drying properties is the so called "non- microporous film type", also known as "swellable type", as proposed in several patent publications such as DE-A 4 322 178, EP-A-806 299 and JP-A-22 760. For this type of ink-jet recording medium, at least one ink receptive layer is coated on a support such as a paper or a transparent film. The ink receptive layer contains significant amounts of water soluble polymers, such as poly vinyl alcohol, gelatin etc. Both types of ink jet recording media have their advantages and disadvantages. The microporous type has generally a high absorbing capacity, while it has deficiencies in the gloss, the dye fading properties and image density. On the other hand, the swellable type is better in dye fading and gloss properties, but it absorbs the ink solvent slowly. Attempts have been made to improve the dye fading properties, e.g. by adding light resisting imparting chemicals to microporous media as described in US 6 652 931. US 5 672 424 and US 6 624 743 describe the application of lightfastness inducing agents dissolved in water. Although some improvement can be obtained by the methods above, there remains a need for low cost ink -jet material with good image printing quality, good drying properties, good resistance against dye fading and having at the same time good behaviour on bleed, beading and matte appearance at high density parts. It is towards fulfilling this need that the present invention is directed.
Summary of the invention The object of the present invention is thus to provide a recording medium having especially good drying and light fastness properties, said recording medium more in particular being suited to produce images of photographic quality. It is a further object of this invention, to provide a recording medium which gives no beading, has no matte appearance at high densities and has good bleeding properties It has been found that these objectives can be met by providing a recording medium comprising a support and an ink receiving layer adhered to said support, where the ink receiving layer is a multilayer comprising at least one underlayer and at least one overlayer in which the overlayer comprises at least one type of modified gelatin and wherein at least one layer of the multi layers comprises at least one type of hydrophobic UV absorbing agent.
Detailed description The invention is directed to a recording medium comprising a support and an ink receiving layer adhered to said support, where the ink receiving layer is a multilayer comprising at least one underlayer and at least one overlayer in which the overlayer comprises at least one type of modified gelatin and wherein at least one layer of the multi layers comprises a hydrophobic UV absorbing agent. This invention is also related to the manufacture of such a recording medium and to the use of this medium. According to this invention good properties of ink jet medium in terms of light fastness, beading, colour bleeding and ink absorption can be achieved by applying an ink receptive layer, which is a multilayer, wherein the composition of each layers is designed such that a specific function is accommodated in that layer. This invention is characterized by the presence of at least one type of modified gelatin in the overlayer, and the presence of at least one UV absorbing agent in one of the layers. The underlayer is a layer that is closer to the support than the overlayer. The overlayer in the medium of the present invention is generally the toplayer, viz. the layer that is furthest away from the support and that is contacted first with the ink upon printing. It is possible to provide a further layer on the overlayer, which further layer then becomes the toplayer. Both the overlayer and the underlayer of this invention may be a multilayer of sublayers. The total number of sublayers is not particularly limited and depends largely on the available technique for application of layers and the required ink receiving properties of the ink receiving layer. The total number of sublayers may be from 2 to 25, more preferably from 3 to 17. Principally, any kind of UV agent can be applied for the purpose of providing the ink jet media with good light fastness properties. Depending on the chemical structure of the UV agent, it has been found that some UV agents are more efficient to be used in this invention and some are less. It was found that in a multilayer coating, water soluble UV absorbing agents are generally less efficient compared to hydrophobic UV agents. Without wishing to be bound by theory, it is assumed that this is because water soluble UV agents have the ability to diffuse to all other layers. The term "hydrophobic UV agent" as used herein, refers to a limited solubility of the UV agent in water at 20°C and at atmospheric pressure. Typical value for the solubility of a hydrophobic UV agent in water is less than 1 g/L. There are various ways in which the hydrophobic UV agents can be added. In one embodiment the hydrophobic UV agent is added as such to a solution of a hydrophilic polymer in water to give a dispersion. The hydrophilic polymer is selected from the group of gelatin, pol vinylalcohol (PVA), polyvinylpyrollidone (PVP), carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC) and the like. The most suitable hydrophilic polymer is gelatin. The gelatin can be any of modified or non-modified gelatins. Examples of non-modified gelatins are alkali-treated gelatin (cattle bone or hide gelatin), acid-treated gelatin (pigskin, cattle/pig bone gelatin), or hydrolyzed gelatin. Examples of modified gelatins are acetylated gelatin, phthalated gelatin, quaternary ammonium modified gelatin, et. cetera. The gelatins can be used singly or in combination. After the hydrophobic UV agent is added to the solution of the hydrophilic polymer in water, a dispersion is made using one of the techniques known in the art. These methods include methods using a high speed rotating disk, rotor stator methods, methods using any conventional colloid mill, a method using a homogeniser and the like. Preferably one or more surfactants and/or stabilisers are added before or after the dispersion process. Surfactants suitable for the practice of this invention are for example: sulfosuccinic acid alkyl ester such as Aerosol OT, alkyl aryl sulfonates, potassium salts of alkyl naphthalene sulfonic acids, sodium dialkyl naphthalene sulfonate, sodium alkyl naphthalene sulfonate, sodium dodecylsulfate, sodium dodecylbenzenesulfonate, fatty acid esters of sorbitan, tetrasodium N-(l,2- dicarboxyethyl)-N-octyldecylsulfosuccinamate and the like. These surfactants can be used alone or as a mixture. The quantity of the surfactant used or the mixture of surfactants most general is generally between 4 and 10 % of the hydrophobic UV agent amount. Several methods and suitable compounds are disclosed in JP -2001/312025 which is incorporated herein by reference in its entirety. In another embodiment the hydrophobic UV agent is added as an oil-in- water emulsion. The steps for making the oil-in-water emulsion are: (1) dissolving the hydrophobic UV agent in a high boiling organic solvent in the presence or absence of a co-solvent; (2) dissolving the hydrophilic polymer in water; (3) emulsifying the UV agent solution into the hydrophilic polymer solution by vigorous stirring, by applying hig -pressure homogenisation, by treatment with ultrasonic frequencies, or any other method known in the art. The high -boiling organic solvents of this invention preferably have a boiling point of not lower than 175 °C at normal pressure. For example, trialkyl phosphates and triaryl phosphates such as trihexyl, trioctyl, tridecyl, tris(butox eth l), tris(haloalkyl), trixylenyl and tricresyl phosphate, can be used for preparing oil-in-water emulsions. Also phthalate esters, citric esters, benzoic esters, fatty acid esters and fatty acid amides, as well as hydrocarbons such as n-decane or n-dodecane can be used. Organic solvents having a boiling point of not lower than about 30 °C, preferably not lower than about 50 °C, but not higher than about 160 °C can be used as co-solvents. Examples of the co- solvents include ethyl acetate, butyl acetate, ethyl propionate, methyl ethylketone, cyclohexanone, 2-ethoxyetlryl acetate and the like. The suitable hydrophilic polymer and surfactant needed to make a stable oil -in water emulsion can be selected from the groups mentioned before. Preferable hydrophilic polymers are gelatine and the preferred surfactants are sodium dodecylbenzenesulfonate, Aerosol OT, and combination thereof. The average particle size of the oil droplets of the oil-in-water emulsion is preferably smaller than 500 nanometer and more preferably smaller than 300 nanometer. The under limit of the particle size is mainly determined by the used recipe and the mechanical forces used to make the oil-in-water emulsion. The typical average size of the particle size is mostly from 50 to 300 nm. The UV agent may be applied in any layer of the ink receptive layer, however it has been found that an optimum dye fading prevention can be achieved by applying the UV agent in the under layer that is directly adjacent to (viz. in contact with) the overlayer. In another embodiment, the UV agent may be further applied in several underlayers. This embodiment is especially advantageous in case the support does not have sufficient capacity to absorb remaining UV light that penetrates the ink receptive layer. The reflected UV light may than be absorbed by UV agents applied in the underlayer close to the substrate. Although it is preferred to select a hydrophobic UV agent, it is also possible to apply water soluble UV agents in the above mentioned embodiments. Suitable UV agents are selected from the group consisting of purine compounds, pyrimidine compounds, benzimidazole compounds, imidazolidine compounds, urazole compounds, pyrazole compounds, triazole compounds, benzotriazole compounds, tetrazole compounds, pyrazine compounds, cinnamate .compounds, aminobutadien compounds and mixtures thereof. Examples of UV agent are those described in Research Disclosure RD24239, RD290119, RD30326, EP-A 0 673 783, GB-A 2088 777, EP-A 0955180, EP-A-0 738 718, US-A-4926190 and in Ullmann's Encyclopedia of Industrial Chemistry, 5th completely revised edition 1992, volume 20, page 468-471. Suitable UV absorbers are also compounds containing a triazine skeleton. These compounds are described, for example, in JP-A-46-3335, JP-A- 55-152776, JP-A-5-197074, JP-A-5-232630, JP-A-5-307232, JP-A-6-211813, JP- A-8-53427, JP-A-8-234364, JP-A-8-239368, JP-A-9-31067, JP-A-10JP-A-10- 147577, JP-10-182621, JP-T-8-501291 ("JP-T" means published searched patent publication). EP-A- 0711804 and DE-A- 19739797 are preferable. Preferred UV agents are benzotriazole compounds, such as 2-(2- hydroxy-5'methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t- butylphenyl)benzotriazole, 2-(2'-hydiOxy-3',5'-di-t-butylphenyι)-5- chlorobenzotriazole , 2 - (2'-hy droxy- 5'-t-butylphenyl)benzotriazole , 2 -(2' - hydroxy-5'-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-sec-butyl-5'-t- butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-sec-butyl-5'-t-butylphenyi)-5- chlorobenzotriazole, 2-(2'-hydroxy-4'-n-hexyloxyphenyι)benzotriazole, 2-(2'- hydroxy-5'-isoocytlphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t- amy lp he nyl)benzo triazole, 2-(2'-hydroxy-5'-isooctylphenyl)-5'-methyl- benzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl) benzotriazole, 2-(2'-hydroxy- 3'-t-butyl-5'mehtylphenyι) benzotriazole, 2-(2'-hydroxy-3'-sec-dodecyl- 5'mehtylphenyι) benzotriazole, as well as the benzotriazole compounds described in EP-A-0 738 718, the benzotriazole compounds described in US-A- 4926190, and mixtures thereof. The UV agent may be added in the amount from 0.03 g/m2 to 10 g/m2, preferable between 0.03 g/m2 and 5 g/m2. The overlayer of this invention comprises a modified gelatin, and may further comprise water insoluble particles inter alia to regulate the slip behaviour and optionally one or more water soluble polymers, surfactants and other additives to optimise the surface properties. The term "modified gelatin" as tised herein, refers to gelatin compounds in which at least part of the NH2 groups is chemically modified. A variety of modified gelatins can be used in the overlayer. Good results are obtained, when at least 30% of the NH2 groups of the gelatin is modified by a condensation reaction with a compound having at least one carboxylic group as described among others in DE-A- 19721238. The compound having at least one carboxylic group can have an other functional group like a second carboxylic group and a long aliphatic tail, which in principle is not modified. Long tail in this context means from at least 5 to as much as 25 C atoms. This aliphatic chain can be modified still to adjust the properties like water solubility and ink receptivity. Preferred modified gelatins comprise an alkyl group (more preferably a Cs-C25-alkyl group), a fatty acid group (more preferably C5- C25-fatty acid group), or both. Even more preferably the gelatins comprise a C - Cis-alkyl group, a C7-Cιs-fatty acid group, or both. Especially preferred gelatins of this type are succinic acid modified gelatins in which the succinic acid moiety contains an aliphatic chain from at least 5 to 25 carbon-atoms, where the chain can still be modified to a certain extend to adjust the water soluble properties or ink receptive properties. Most preferred is the use of dodecenylsuccinic acid modified gelatin, in which at least 30% of the NH2 groups of the gelatin have been modified with said dodecenylsuccinic acid. Another method for obtaining modified gelatin is described in EP-A- 0576911, where said gelatin is formed from gelatin containing pendant amine groups and pendant carboxylic groups wherein at least one amine group of said gelatin is modified to form an amide of the formula -NHCOR. The process typically involves reaction of an amine group with an activated carboxyl, i.e. a reaction product of a carboxyl activating agent and carboxylic acid, i.e., RCOOH wherein R represents substituted or unsubstituted alkyl of 1-10 carbons, substituted or unsubstituted aryl of 6-14 carbons, or substituted or ύnsubstituted arylalkyl of 7-20 carbons. Other suitable methods are described by V.N. Izmailova, et.al (Colloid Journal, vol. 64, No. 5, 2002, page 640-642), and by O. Toledano, et. al (Journal of Colloid and Interface Science 200, page 235-240) wherein hydrophobic groups are attached to gelatin molecules by reacting gelatin with respectively N-Hydroxysuccinimide ester of caprylic acid and N- Hydroxysuccinimide ester of various fatty acids (C4-C16). Other modified gelatins giving good results are gelatins modified to have quaternary ammonium groups. An example of such a gelatin is the "Croquat™" gelatin produced by Croda Colloids Ltd. Still other modified gelatins known in the common gelatin technology, such as phtalated gelatin and acetylated gelatins are also suitable to be used in this invention. The modified gelatin can be used alone or in combination with another water soluble polymer. Examples of these polymers include: fully hydrolysed or partially hydrolysed polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinylpyrolidone, any gelatin whether lime-processed or acid processed made from animal collagen, preferably gelatin made from pig skin, cow skin or cow bone, polyethylene oxide, poly aery lamide, and the like. The modified gelatin is preferably applied in the overlayer in an amount ranging from 0.3 to 5 g/m2and most preferably from 0.5 to 3 g/m2. A suitable amount of the water soluble polymer in the mixture is varying between 0 and 75 wt% of the amount of the modified gelatin. In case said water soluble polymer amount is higher than 75 wt%, the advantages of the modified gelatin may become less pronounced. The mere application of the modified gelatin or mix of modified gelatin and water soluble polymers improves the characteristics with respect to drying and finger smearing properties. A further improvement of above mentioned properties can be obtained by including in the overlayer a fluorosurfactant in the amount between 2.5 mg/m2 and 250 mg/m2. It was found that this kind of surfactants improves amongst others the gloss and beading. Beading is denned as the phenomenon that large ink dots become visible on the printed image. The mechanism of "beading" is not clear yet. One hypothesis is that several small ink drops coalesce with each other on the surface of the ink jet media and form large ink droplets. The term "fluorosurfactant" as used herein, refers to surfactants (viz. molecules having a hydrophilic and a hydrophobic part) that contain fluorocarbon or a combination of fluorocarbon and hydrocarbon as the hydrophobic part. Suitable fluorosurfactants may be anionic, non-ionic or cationic. Examples of suitable fluorosurfactants are: fluoro C2-C20 alkylcarboxylic acids and salts thereof, disodium N-perfluorooctanesulfonyl glutamate, sodium 3-(fluoro-C6-Cn alkyloxy)-l-C3-C alkyl sulfonates, sodium 3-(omega -fluoro-Ce-Cs alkanoyl-N-ethylamino)-l-propane sulfonates, N-[3- (perfluorooctanesulfonamide)-propyl]-N,N-dimethyl-N-carboxymethylene ammonium betaine, perfluoro alkyl carboxylic acids (e.g. perfluoro C7-C13 alkyl carboxylic acids and salts thereof, perfluorooctane sulfonic acid diethanolamide, Li, K and Na perfluoro C4-C12 alkyl sulfonates, Li, K and Na N-perfluoro C4-C13 alkane sulfonyl — N- alkyl glycine, fluorosurfactants commercially available under the name Zonyl® (produced by E.I. Du Pont) that have the chemical structure of fCH2CH2SCH2CH2CO2Li or RfCH2CH2O(CH2CH20)χH wherein Rf = F(CF2CF2)3-8 and x =-0 to 25, N- propyl-N-(2-hydroxyethyl)perfluorooctane sulfonamide, 2-sulfo-l,4- bis(fluoroalkyl)butanedioate, 1,4-bis (fluoroalkyl)-2-[2-N,N,N- trialkylammonium) alkyl amino] butanedioate, perfluoro Ce-Cio alkylsulfonamide propyl sulfonyl glycinates, bis-(N-perfluorooctylsulfonyl-N- ethanolaminoethyl)phosphonate, mono-perfluoro Ce-Cie alkyl-ethyl phosphonates, and perfluoroalkylbetaine. Also useful are the fluorocarbon surfactants described e.g. in US-A-4 781 985 and in US-A-5 084 340. Preferably the fluorosurfactant is chosen from Li, K and Na N-perfluoro C4-C13 alkane sulfonyl -N- alkyl glycine, 2-sulfo-l,4.bis(fluoroalkyl)butanedioate, 1,4-bis (fluoroalkyl)-2-[2-(N,N,N- trialkylammonium alkyl amino] butanedioate, perfluoroalkyl subsitituted carboxyhc acids commercially available under the name Lodyne® (produced by Ciba Specialty Chemicals Corp.) and fluorosurfactants commercially available under the name Zonyl® (produced by E.I. Du Pont) that have the chemical structure of RfCH2CH2SCH2CH2CO2Li or RfCH2CH2θ(CH2CH2θ)xH wherein Rf = F(CF2CF2)3-8 and x = 0 to 25. Beside the modified gelatin or modified gelatin/water soluble polymer mixture and fluorosurfactant it may be desirable to add in the overlayer an anti-blocking agent to prevent image transfer when several printed inkjet mediums are piled up. Very suitable anti -blocking agents (also known as matting agents) have a particle size from 1 to 20 μm, preferably between 2 and 10 μm. The amount of matting agent is from 0.01 to 1 g/m2, preferably from 0.02 to 0.5 g/m2. The matting agent can be defined as particles of inorganic or organic materials capable of being dispersed in a hydrophilic organic colloid. The inorganic matting agents include oxides such as silicon oxide, titanium oxide, magnesium oxide and aluminium oxide, alkali earth metal salts such as barium sulphate, calcium carbonate, and magnesium sulphate, and glass particles. Besides these substances one may select inorganic matting agents which are disclosed in West German Patent No. 2,529,321, British Patent Nos. 760,775 and 1,260,772, U.S. Pat. Nos. 1,201,905, 2,192,241, 3,053,662, 3,062,649, 3,257,296, 3,322,555, 3,353,958, 3,370,951, 3,411,907, 3,437,484, 3,523,022, 3,615,554, 3,635,714, 3,769,020, 4,021,245 and 4,029,504. The organic matting agents include starch, cellulose esters such as cellulose acetate propionate, cellulose ethers such as ethyl cellulose, and synthetic resins. The synthetic resins are water insoluble or sparingly soluble polymers which include a polymer of an alkyl(meth) aery late, an alkoxyalkyl(meth) aery late, a glycidyl(meth)acrylate, a (meth)acrylamide, a vinyl ester such as vinyl acetate, acrylonitrile, an olefin such as ethylene, or styrene and a copolymer of the above described monomer with other monomers such as acrylic acid, methacrylic acid, alpha, beta -unsaturated dicarboxylic acid, hydroxyalkyl(meth)acrylate, sulfo alky l(meth) aery late and styrene sulfonic acid. Further, a benzoguanamin-formaldehyde resin, an epoxy resin, nylon, polycarbonates, phenol resins, polyvinyl carbazol or polyvinylidene chloride can be used. Besides the above are used organic matting agents which are disclosed in British Patent No. 1,055,713, U.S. Pat. Nos. 1,939,213, 2,221,873, 2,268,662, 2,322,037, 2,376,005, 2,391,181, 2,701,245, 2,992,101, 3,079,257, 3,262,782, 3,443,946, 3, 516,832, 3,539,344,554, 3,591,379, 3,754,924 and 3,767,448, Japanese Patent O.P.I. Publication Nos. 49- 106821/1974 and 57-14835/1982. These matting agents may be used alone or in combination. The overlayer may optionally include thickener agents, biocides crosslinking agents and further various additives such as colorants, colored pigments, pigment dispersants, mold lubricants, permeating agents, fixing agents for ink dyes, anti-oxidants, dispersing agents, anti-foaming agents, leveling agents, fluidity improving agents, antiseptic agents, optical brightening agents, viscosity stabilizing and/or enhancing agents, pH adjusting agents, anti-mildew agents, anti-fungal agents, agents for moisture- proofing, agents for increasing the stiffness of wet paper, agents for increasing the stiffness of dry paper and anti-static agents. The above-mentioned various additives can be added ordinarily in an amount, such that the total additives content ranges from 0 to 10 weight% based on the solid content of the overlayer composition. In another embodiment of this invention the beneficial effects of the modified gelatin and the fluorosurfactant is generated by applying these compounds in separate overlayers, meaning, that also the overlayer is a multilayer. In this case it is preferable to have the fluorosurfactant in a coating layer farthest away from the substrate and the modified gelatin applied under this layer. Also the underlayer can be a multilayer of sublayers. The underlayer preferably comprises gelatin and a hydrophilic polymer, a UN compound (as mentioned before) and optionally additives to adjust the physical properties. This swellable underlayer determines mainly the physical properties like water uptake, drying speed, brittleness and curl. It was found that in case the underlayer is a multilayer it is beneficial to apply different concentrations of gelatin and water soluble polymer in the sublayers of the underlayer. A lower concentration of gelatin and water soluble polymer in the sublayer closest to the support enables a lower viscosity of the mixture which improves the coatability and allows higher coating speeds. In a specific embodiment an adhesion promoting layer is applied between the support and the underlayer to enhance the adhesion of the coated layers onto the support. This adhesion promoting layer may be coated in a separate step or simultaneously with the receiving layers. There is a variety of gelatins, both non-modified as well as modified gelatins which can be used in the underlayer. Examples of non-modified gelatins are alkali-treated gelatin (cattle bone or hide gelatin), acid -treated gelatin (pigskin, cattle/pig bone gelatin), or hydrolyzed gelatin. Examples of modified gelatins are acetylated gelatin, phthalated gelatin, quaternary ammonium modified gelatin, et cetera. These gelatins can be used singly or in combination for forming one or more of the layers of the underlayer. Acid and alkali treated gelatins are preferred. Water soluble polymers suitable to be mixed with the (modified) gelatin include polyvinyl alcohol- (PVA-)based polymers, such as fully hydrolysed or partially hydrolysed polyvinyl alcohol (PVA), carboxylated polyvinyl alcohol, copolymers and terpolymers of PVA with other polymers, watersoluble cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, casein, gum arabic, polyacrylic acid and its copolymers or terpolymers, polymethylacryhc acid and its copolymers or terpolymers, and any other polymers, which contain onomers of carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and crotonic acid, polyvinylpyrolidone (PVP), polyethylene oxide, poly aery lamide, 2-pyrrolidone and its derivatives such as N (2 -hydroxyethyl) - 2-pyrrolidone and N-cyclohexyl-2-pyrrolidone, urea and its derivatives such as irnidazolidinyl urea, diazolidinyl urea, 2 -hydroxyethylethylene urea, and ethylene urea. Water soluble polymers can have very limited compatibility with gelatin. These polymers include fully hydrolyzed or partially hydrolyzed polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyethylene oxide, polyacrylamide , and the like. When a solution of gelatin in water is mixed with a solution in water of one of the above described polymers, micro or macro phase separation occurs in solution which persists in the dried coating. The dried coating exhibits high haze, low transparency, and low gloss. By applying the overlayer of the invention on such an underlayer, it will improve the appearance significantly. It is however better to use the inventive overlayer on an underlayer in which no phase separation between the gelatin and the water soluble polymer occurs. The system of a mixture of gelatin and a water soluble polymer is very well illustrated by means of a gelatin/PEO mixture as example. A homogeneous gelatin -PEO mixture, i.e. a mixture where no phase separation occurs, may be obtained by adjusting the pH of the mixture. However there is no unique rule to determine the pH at which there is no phase separation. The best way is to follow the practical approach by making the required mixture of gelatin and water soluble polymer in water and adding alkali or acid until a homogeneous solution is obtained. The suitable pH range mainly depends on the gelatin type used and type of the water soluble polymer. It was found that (modified) acid treated gelatins having an iso-electric-point (IEP) of between 6 and 11 give a homogeneous solution with polyethylene oxide (PEO) at a pH below 5. At pH between 5 and 10, the mixture remains turbid, which indicate that the mixture is not homogeneous. At a pH higher than 11, a homogeneous solution can be obtained. .For a lime treated gelatin, that may have an IEP value of between 4 and 6, a homogeneous mixture between gelatin and PEO can be obtained at a broader pH ranges, i.e. at a pH value lower than 4.5 or at a pH value higher than 6. In addition to the above mentioned pH adjustment, we have also found, that it is not only important to have a homogeneous solution, but it is also beneficial to have a molecular weight of PEO of at least 100 000. A lower MW might also give satisfactory results, but in general most of the important properties, like curling, drying speed and brittleness improve when using a high MW PEO. In addition to this, it appeared to be beneficial to use an underlayer comprising various layers, in which the various layers have a different gelatin/PEO ratio. We have found that a low gelatin/PEO ratio in the layer adjacent to the overlayer and a higher gelatin/PEO ratio at the layers nearer to the support have a beneficial effect on properties like bleeding and beading. More specifically gelatin/PEO ratios (wt./wt.) in the layer nearest to the overlayer preferably vary between 1/1 to 8/1 and the gelatin/PEO ratios (wt./wt.) in the layers nearest to the support preferably vary between 1/1 and 12/1, preferably with the condition, that the gelatin/PEO ratio of the layer adjacent to the overlayer is always lower, than the ratio of the other gelatin - PEO layers. When using more gelatin-PEO layers in the underlayer it is further beneficial to use a gradient for the gelatin/PEO ratio, meaning, that the gelatin/PEO ratio is lowest in the layer adjacent to the overlayer and said ratio is highest for the layer nearest to the substrate. The homogeneous gelatin-PEO solution of the underlayer, which is applied to the substrate has a gelatin concentration between 5 and 20 wt.%. Apart from using PEO, similar results can be obtained using mixtures of gelatin and other water soluble polymers having a limited compatibility with each other. It has been found by the present inventors that one may substitute the PEO with other water soluble polymers mentioned above such as PVP or PVA or a mixture between two or more water soluble polymers s ch as PEO and PVP. The ratio between the gelatin and said water soluble polymer(s) are preferably in the same ranges as described above for gelatin-PEO system. Good results are obtained with PVA-based polymers. In general a large variety of PVA-based polymers can be used, but the preferred PVA-based polymers are those which have been modified to give a good miscibility with aqueous gelatin solutions. These modifications are such, that in the PVA-based polymer back bone groups are introduced which provide a hydrogen bonding site, an ionic bonding site, carboxylic groups, sulphonyl groups, amide groups and the like, thus providing a modified PVA-based polymer. A modified PVA- based polymer giving very good results is a poly (vinyl alcohol) -co-poly (n- vinyl formamide) copolymer (PVA-NVF). Very suitable PVA-NVF copolymers for use with the present invention are the copolymers described in WO-A-03/054029, which have the general formula I:
Figure imgf000018_0001
wherein n is between 0 and about 20 mole percent; m is between about 50 and about 97 mole percent; x is between 0 and about 20 mole percent; y is between 0 and about 20 mole percent; z is between 0 and about 2 mole percent and x+y is between about 3 and about 20 mole percent; Ri, and R3 are independently H, 3-propionic acid or CI-CG alkyl ester thereof, or is 2-methyl-3-propionic acid or Ci-Ce alkyl ester thereof; and R2 and R4 are independently H or CI-CG alkyl. The water soluble polymer is preferably applied for the underlayer i an amount ranging from 0.5 to 15 g/m2, more preferably from 1.0 to 8.0 g/m2. The homogeneous aqueous solution of the underlayer may further contain the following ingredients in order to improve the ink receiving layer properties with respect to ink receptivity and the physical strength of the layer: - One or more plasticizers, such as ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, glycerol monomethylether, glycerol monochlorohydrin, ethylene carbonate, propylene carbonate, tetrachlorophthahc anhydride, tetrabromophthalic anhydride, urea phosphate, triphenylphosphate, glycerolmonostearate, propylene glycol monostearate, tetramethylene sulfone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, and polymer lattices with low Tg-value such as polyethylacrylate, poly me thy lacry late and the like. - One or more fillers. The presence of porosity imparting particles is not essential for this invention. Nevertheless, some of the conventional fillers may be used, some of which fillers may impart further porosity. Both organic and inorganic particles can be used as fillers. Useful filler examples are represented by silica (colloidal silica), alumina or alumina hydrate (aluminazol, colloidal alumina, a cat ion aluminum oxide or its hydrate and pseudo-boehmite), a surface-processed cat ion colloidal silica, aluminum silicate, magnesium silicate, magnesium carbonate, titanium dioxide, zinc oxide, calcium carbonate, kaolin, talc, clay, zinc carbonate, satin white, diatomaceous earth, synthetic amorphous silica, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide and synthetic mica. Useful examples of organic fillers are represented by polystyrene, polymethacrylate, polymethyl-methacrylate, elastomers, ethylene -vinyl acetate copolymers, polyesters, polyester-copolymers, polyacrylates, polyvinylethers, polyamides, polyolefins, polysilicones, guanamine resins, polytetrafluoroethylene, elastomeric styrene-butadiene rubber (SBR), urea resins, urea-formalin resins. Such organic and inorganic fillers may be used alone or in combination. - One or more mordants. Mordants may be incorporated in the ink- receptive layer of the present invention. Such mordants are represented by cationic compounds, monomeric or polymeric, capable of complexing with the dyes used in the ink compositions. Useful examples of such mordants include quaternary ammonium block copolymers. Other suitable mordants comprise diamino alkanes, ammonium quaternary salts and quaternary acrylic copolymer latexes. Other suitable mordants are fluoro compounds, such as tetra ammonium fluoride hydrate, 2,2,2-trifluoroethylamine hydrochloride, 1- (alpha, alpha, alpha -trifluoro-m-tolyl) piperazine hydrochloride, 4-bromo- alpha, alpha, alpha -trifluoro-o-toluidine hydrochloride, difluorophenylhydrazine hydrochloride, 4-fluorobenzylamine hydrochloride, 4- fluoro- alpha, alpha -dimethylphenethylamine hydrochloride, 2- fluoroethylaminehydrochloride, 2 -fluoro- 1-methyl pyridinium-toluene sulfonate, 4-fluorophenethylamine hydrochloride, fluorophenylhydrazine hydrochloride, l-(2-fluorophenyl) piperazine monohydrochloride, 1-fluoro pyridinium trifluorome thane sulfonate. - One or more conventional additives, such as: • pigments: white pigments such as titanium oxide, zinc oxide, talc, calcium carbonate and the like; blue pigments or dyes such as cobalt blue, ultramarine or phthalocyanine blue; magenta pigments or dyes such as cobalt violet, fast violet or manganese violet; • biocides; • pH controllers; • preservatives; • viscosity modifiers; • dispersing agents; • brightening agents; • dye fading preventing agents; • antistatic agents; and/or • anionic, cationic, non-ionic, and/or amphoteric surfactants, typically used in amounts ranging from 0.1 to 1000 mg/m2, preferably from 0.5 to 100 mg/m2. These additives may be selected from known compounds and materials in accordance with the objects to be achieved. The above-mentioned additives (plasticizers, fillers/pigments, mordants, conventional additives) may be added in a range of 0 to 30% by weight, based on the solid content of the water soluble polymers and/or gelatin in the underlayer. The particle sizes of the non water-soluble particulate additives should not be too high, since otherwise a negative influence on the resulting surface will be obtained. The used particle size should therefore preferably be less than 10 μm, more preferably 7 μm or less. The particle size is preferably above 0.1 μm, more preferably about 1 μm or more for handling purposes. The gelatin is preferably used in a total amount of from 1 to 30 g/m2, and more preferably from 2 to 20 g/m2. The amount of hydrophilic polymer used in a certain formulation is typically in the range from 100 mg/m2 to 30 g/m2 and more preferably between 200 mg/m2 and 20 g/m2. When preparing the ink -jet-receiving sheet by coating a plurality of layers, each layer comprises an amount of gelatin ranging from 0.5 to 10 g/m2. If desired, the gelatin in the image -recording elements of the present invention can be cross-linked in order to impart mechanical strength to the layer. This can be done by any cross-linking agent known in the art. For gelatin, there is a large number of known cross-linking agents- also known as hardening agents. Examples of the hardener include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedion, bis (2-chloroethylurea), 2-hydroxy-4, 6- dichloro-l,3,5-triazine, reactive halogen-containing compounds disclosed in US-A-3 288 775, carbamoyl pyridinium compounds in which the pyridine ring carries a sulphate or an alkyl sulphate group disclosed in US-A-4 063 952 and US-A-5 529 892, divinylsulfones, and the like. These hardeners can be used singly or in combination. The amount of hardener used, preferably ranges from 0.1 to 10 g, and more preferably from 0.1 to 7 g based on 100 g of gelatin contained in the ink-receiving layer. For PVA, for example, it is preferable to choose a cross-linking agent selected from borax, glyoxal, dicarboxylic acids and the like. The process for producing a recording medium comprises the steps of: preparation of at least one aqueous mixture comprising at least a modified gelatin for the overlayer and preparation of one or more homogeneous aqueous mixtures for one or more underlayers. The process further includes the preparation of an oil-in water emulsion comprising one or more hydrophobic UV agents dissolved in a high boiling organic solvent and optionally in the presence of a low boiling organic co-solvent, or alternatively the preparation of a dispersion comprising one or more hydrophobic UV agents in a hydrophilic solvent, followed by mixing said oil-in-water emulsion or said dispersion with at least one of said mixtures for the underlayers or the overlayer to give a homogenous emulsion. The resulting formulations for the overlayer(s) and underlayer or underlayers can be coated consecutively or simultaneously to a support by any method known in the art. The coating methods are for example, a curtain coating, an extrusion coating, an air-knife coating, a slide coating, a roll coating method, reverse roll coating, dip coating processes and a rod bar coating. The support used in this invention may suitably be selected from a paper, a photographic base paper, a paper coated on both sides with a polymer layer, pigment coated paper, a synthetic paper or a plastic film in which the top and back coatings are balanced in order to minimise the curl behaviour. The backside coating comprises gelatin or a water soluble polymer in an amount ranging preferably from 1 to 20 g/m2, more preferably from 4 to 15 g/m2. The optimum amount of the backside coating depends on the type of gelatin, the. type of water soluble polymer and on the composition of the layers at the ink receiving side of the medium and is determined experimentally. The preferred polymer for the backside coating is gelatin. An important characteristic of the inkjet recording medium is the gloss. It has been found that the gloss of the medium can be improved by selecting the appropriate surface roughness of the used support. It was found, that providing a support having a surface roughness characterised by the value Ra being less than 1.0 μm, preferably below 0.8 μm a very glossy medium can be obtained. A low value of the Ra indicates a smooth surface. The Ra is measured according to DIN 4776; software package version 1.62 with the following settings:
(1) Point density 500 P/mm (2) Area 5.6 x 4.0 mm2 (3) Cut-off wavelength 0.80 mm (4) Speed 0.5 mm/sec, using a UBM equipment. The base paper to be used as the support for the present invention is selected from materials conventionally used in high quality printing paper. Generally it is based on natural wood pulp and if desired, a filler such as talc, calcium carbonate, TiO2, BaS04, and the like can be added. Generally the paper also contains internal sizing agents, such as alkyl ketene dimer, higher fatty acids, paraffin wax, alkenylsuccinic acid, epichlorhydrin fatty acid amid and the like. Further the paper may contain wet and dry strength agents such as a polyamine, a poly-amide, poly aery lamide, poly-epichlorhydrin or starch and the like. Further additives in the paper can be fixing agents, such as aluminium sulphate, starch, cationic polymers and the like. The Ra value for a normal grade base paper is well above 1.0 μm typically above 1.3 μm. In order to obtain a base paper with a Ra value below 1.0 μm such a normal grade base paper can be coated with a pigment. Any pigment can be used. Examples of pigments are calcium-carbonate, TiO2, BaSO4, clay, such as kaolin, styrene- acrylic copolymer, Mg-Al-silicate, and the like or combinations thereof. The amount being between 0.5 and 35.0 g/m2 more preferably between 0.5 and 20.0 g/m2. This pigmented coating can be applied as a pigment slurry in water together with a suitable binders like styrene-butadiene latex, methyl methacrylate-butadiene latex, polyvinyl alcohol, modified starch, polyacrylate latex or combinations thereof, by any technique known in the art, like dip coating, roll coating, blade coating or bar coating. The pigment coated base paper may optionally be calendered. The surface roughness can be influenced by the kind of pigment used and by a combination of pigment and calendering. The base pigment coated paper substrate has preferably a surface roughness between 0.4 and 0.8 μm. If the surface roughness is further reduced by super calendaring to values below 0.4 μm the thickness and stiffness values will generally become below an acceptable level. The ink receiving multilayer of the present invention can be directly applied to the pigment coated base paper. In another embodiment, the pigment coated base paper having a pigmented top side and a back-side is provided on both sides with a polymer resin through high temperature co-extrusion giving a laminated pigment coated base paper. Typically temperatures in this (co-) extrusion are above 280 °C but below 350 °C. The preferred polymers used are poly olefins, particularly polyethylene. In a preferred embodiment the polymer resin of the top side comprises compounds such as an opacifying white pigment e.g. TiO2 (anatase or rutile), ZnO or ZnS, dyes, coloured pigments, including blueing agents, like e.g. ultramarine or cobalt blue, adhesion promoters, optical brighteners, antioxidant and the like to improve the whiteness of the laminated pigment coated base paper. By using other than white pigments a variety of colors of the laminated pigment coated base paper can be obtained. The total weight of the laminated pigment coated base paper is preferably between 80 and 350 g/m2. The laminated pigment coated base paper shows a very good smoothness, which after applying the ink receiving layer of the present invention results in a recording medium with excellent gloss. Examples of the material of the plastic film are polyolefins such as polyethylene and polypropylene, vinyl copolymers such as polyvinyl acetate, polyvinyl chloride and polystyrene, polyamide such as 6, 6 -nylon and 6-nylon, polyesters such as polyethylene terephthalate, polyethylene -2 and 6- naphthalate and polycarbonate, and cellulose acetates such as cellulose triacetate and cellulose diacetate. The support may be subjected to a corona treatment in order to improve the adhesion between the support and the ink receiving layer. Also other techniques, like plasma treatment can be used to improve the adhesion. The swellable ink-receiving layer has a dry thickness from 1 to 50 micrometers, preferably from 5 to 25 and more preferably between 8 and 20 micrometers. If the thickness of said ink receiving layer is less than 1 micrometer, adequate absorption of the solvent will not be obtained. If, on the other hand, the thickness of said ink receiving layer exceeds 50 micrometers, no further increase in solvent absorptivity will be gained. The media of the present invention can be used in any printing application where photographic quality is required. Although the invention is described herein with particular reference to inkjet printing, it will be apparent to the skilled person that the high quality recording media of the present invention are not limited to inkjet recording media (viz. media suitable to be printed on using inkjet printers), but that it is within the scope of the present invention to provide recording media that are suitable for creating high quality images by using other techniques as well, such as Giclee printing, colour copying, screen printing, gravure, dye -sublimation, flexography, and the like. The media of the present invention show excellent behavior with respect to properties as lightfastness, coloration, beading and glossiness, as is illustrated in more detail by the non -limiting examples given below. In particular, the lightfastness of the media according to the present invention, which may be expressed as the remaining color-density percentage after exposing a sample for 144 hrs using a xenon light (85 000 lx) in an Atlas Wether-O -Meter C I 35A (manufactured by Atlas (Illinois, U.S.A.)), may be 80% or more (density measured using a reflection densitometer (X-Rite 310TR)). Furthermore, the media of the present invention may have an excellent coloration behavior, the coloration of the media upon storage at typical storage conditions being minimal. The coloration (viz. the "yellowing" of the white parts of the media of the present invention upon aging) may be assessed using a protocol in which L, a*, b* values are measured by a spectrophotometer (e.g. a MINOLTA CM-1000R). The media of the present invention may have a ΔE (whiteness difference, expressed as b* values measured on a spectrophotometer, before and after aging) value after two weeks of storage at 50°C and 40% relative humidity of less than 5, preferably 2 or less. The present invention will be illustrated in detail by the following non-limiting examples. Unless stated otherwise, all ratios given in the examples are based on weight.
Examples A. Preparation of solution 'A' of the ink receiving layer. A solution containing 50 g of Gelita® Imagel MA (dodecenyl-succinic modified acid treated gelatin from Stoess GmbH, Germany with a modification degree of ca. 40%), 1 g of Zonyl® FSN surfactant (a non-ionic fluoro-carbon type of surfactant) and 949 g of water was prepared at 40°C. The pH of the solution was adjusted to 8.5 by adding NaOH.
B. Preparation of solution 'B' of the ink receiving layer A 20 wt.% solution of a lime processed gelatin was prepared at pH 9. An aqueous solution of 10 wt % polyethylene oxide (PEO) having molecular weight of approximately 100 000 (from Sigma Aldrich chemicals, the Netherlands) was also prepared at pH 9. A homogeneous mixture (viz. no phase separation occurred), of gelatin and PEO having a weight ratio of 6:1 was made by adding 143 g of said PEO solution and 429 g of water into 428 g of said gelatin solution at a temperature of 40°C. This mixture was agitated gently for about 30 minutes.
C. Preparation of solution 'C of the ink receiving layer. Solution 'O was prepared in the same way as solution 'B', except that PEO was replaced by polyvinyl pyrollidone (PVP) having a molecular weight of about 30 000 Daltons (ICN Biochemicals).
D: Preparation of an oil in water emulsion T)'. 120 gram of UV absorbing agent (a mixture of UV-1/UV-2/UV-3/UV- 4= 2/1/1/1; see the chemical formulae UV-1 to UV-4 hereinafter), 40 g dibutyl phtalate, and 20 g of a 20% sorbitane monolaurate methanol solution were mixed in 100 ml of ethyl acetate at 65°C. The solution was dispersed in 500 ml of an aqueous solution containing 20% lime bone gelatin by weight by a homogeniser. After emulsification the solution was diluted up to 1 000 g by water. The size of dispersed droplets was determined by the disc centrifuge particle size measurement and the mean diameter was 130 nm.
E: Preparation of an aqueous UV absorbing agent solution. 105 gram of benzophenon type UV absorber (Lowilite 20S, Great Lakes, USA) was dissolved at room temperature in 895 g of water containing 10 weight % lime processed gelatin. F. Schematic drawing and definition of the layer structure: Structure consisting of at least two underlayers and one overlayer
Overlayer Underlayer 2 Underlayer 1 Laminated Substrate
The underlayers and overlayer containing the solutions mentioned above were fed into a slide coating machine, commonly known in the photographic industry, and coated onto a photographic grade paper having polyethylene laminated at both sides. The flow of the underlayers and that of the overlayer were selected such that, after drying, a total solid content of the underlayers (gelatine + other water soluble polymer) between 8 to 25 g/m2 was obtained and a total solid content of the overlayer between 0.5 and 5 g/m2. After coating, the coated material was chilled at a temperature of ca. 12°C to set the gelatin and then dried with dry air at a maximum temperature of 40°C.
These examples describe one way of applying the invention. An overview of the layer structure of these examples is given in Table 1, below.
Table 1.
Figure imgf000028_0001
Inventive example #1 The overlayer contained a mixture of 100 g of oil in water emulsion - D and 900 g of solution-A and the flow of the overlayer was 40 cc/m2. The underlayer-2 contained a mixture of 50 g of solution-B and 50 g of solution C. The flow of underlayer-2 was 100 cc/m2. The underlayer- 1 contained only solution C and the flow was adjusted at 50 cc/m2.
Inventive example #2 The sample was prepared in the same way as example 1, except for the composition of the overlayer and the underlayer-2. The overlayer contained only solution-A, while the underlayer 2 contained a mixture of 40 g of oil in water emulsion-D, 480 g of solution-B and 480 g of solution-C. The mixture was coated at flow of 100 cc/m2.
Inventive example #3 The sample was prepared in the same way as example 1, except for the overlayer and the underlayer- 1. The overlayer contained solution-A only, while the underlayer-1 contained a mixture of 40 g of oil in water emulsion-D and 960 g of solution-C. The flow of overlayer was kept at 40 cc/m2, while that for the underlayer-1 was adjusted to 100 cc/m2.
Inventive example #4 The sample was prepared in the same way as example 2, except for the composition of underlayer-2. The underlayer 2 contained a mixture of 40 g of benzophenon solution E, 480 g of solution-B and 480 g of solution-C.
Comparative example #5 The comparative example 5 was prepared in the same way as the inventive example 1 except for the composition of the overlayer. The overlayer contained only solution-A. In this example there is no UV agent present in the ink receiving layer.
Comparative example #6 The sample was prepared in the same way as example 2, except for the overlayer. In this comparative example 6 the overlayer which contained solution-A was not coated. In order to keep the total thickness, after drying, the same as in example 2, the flow of underlayer-2 was set to 123 cc/m2.
Comparable example #7 The sample was prepared in the same way as example 4, except for the overlayer. In this comparative example 7 the overlayer which contained a solution-A, was not coated. In order to keep the total thickness, after drying, the same as in example 4, the flow of underlayer-2 was set to 123 cc/m2.
I. Evaluation of the printed image on the media The ink jet media prepared by the above mentioned formulation and said coating process, were printed with a standard image comprising black, cyan, magenta and yellow bars. The image contained also two pictures; - including a portrait' picture and a composition picture. The image was printed at a room conditions (23°C and 48% Relative Humidity (RH)) and the printed materials were kept at this condition for at least 1 hour to dry. A HP Deskjet ® 995c was used to print the images by using the following settings: • Print quality : best • Selected Paper type: HP premium plus photo paper, glossy • Other parameters were according to the factory setting. The quality of the printed images were further analysed visually by analysing the beading behaviour, the glossiness of especially the black area, the dryness of especially the black area, and the bleeding behaviour after some period of time.
J. Definitions of the image evaluation 1. Light fastness Light fastness is one of the factors that determines the dye stability during the. display or storage at light condition. In order to evaluate this behaviour a sample exposed for 144 hrs using a xenon light (85 000 lx) in an Atlas Wether-O-Meter C I 35A, (manufactured by Atlas (Illinois, U.S.A.)). The image density of the colors on the printed area was measured before and after the xenon irradiation by a reflection densitometer (X-Rite 310TR) and expressed as the remaining color-density percentage. The following classification has been defined: O: more than 80% remaining density Δ: 80-60% remaining density X: less than 60% remaining
2. Beading behaviour As set out hereinabove, beading is defined as the phenomenon that large ink dots that become visible on the printed image. The following classification has been defined: O: no beading is observed
Δ: some small spots which is not very visible and/or beading that can be solved by selecting another printer settings. X: clearly visible
3. Glossiness after printing. The glossiness of the image directly after printing and after two days were analysed by observing the reflection of light on the high density area of the print (e.g. black colour). The more reflection was observed, the glossier the printed image. The following classification was defined for judging the Glossiness:
O: Still glossy after 2 days without any defects
Δ: Gloss after printing, but after 2 days some 'matte" spots was observed. X: Matte appearance after printing, or a lot of "matte" spots after 2 days. .Results: The results of the experiments mentioned above can be found in Table 2, below:
Figure imgf000032_0001
From these results it can be concluded that the combination between an overlayer which comprises a modified gelatin and an UV absorber agent in one of the ink receiving layers gives best solution for having a good light fastness property, less coloration and at the same time keeping the glossiness after printing.
UV-1: UV-2:
Figure imgf000033_0001
UV-3: UV-4:
Figure imgf000033_0002

Claims

Claims
1. Recording medium comprising a support and an ink-receiving layer adhered to said support, wherein the ink receiving layer is a multi layer comprising at least one underlayer and at least one overlayer in which at least one overlayer comprises at least one type of modified gelatin and wherein at least one layer of said multi layer comprises at least one type of hydrophobic UV absorbing agent.
2. Recording medium according to claim 1, wherein said UV absorbing agent is present in the underlayer that is located adjacent to the overlayer.
3. Recording medium according to claim 1 or 2, wherein said UV absorbing agent is selected from the families of cinnamates, hydroxybenzophenones, benzotriazoles, aminobutadienes or combinations thereof.
4. Recording medium according to any previous claims, wherein the amount of said UV agent is fronrθ.05 g/m2 to 5.0 g/m2.
5. Medium according to any of the previous claims, wherein said UV absorbing agent is added as an oil in water emulsion.
6. Medium according to claim 5, wherein the average size of the oil droplets is from 50 n - 500 nm, preferably from 50 nm — 300 nm.
7. Medium according to claims 1 to 4 wherein said UV absorbing agent is added as a dispersion in a hydrophilic solvent.
8. Medium according to claim 1-7, wherein said modified gelatin is selected from the group consisting of acetylated gelatin, phthalated gelatin, alkyl quaternary ammonium modified gelatin, succinated gelatin, alkylsuccinated gelatin, gelatin chemically modified with N- hydroxysuccinimide ester of fatty acid, and combinations thereof.
9. Medium according any of the previous claims, wherein said modified gelatin comprises a C5-C25 alkyl group, a C5-C25 fatty acid group, or both; more preferably a C7-C18 alkyl group, a C7-C18 fatty acid group, or both.
10. Medium according any of the previous claims in which the modified gelatin js used in an amount of 0.3 to 5.0 g/m2, more preferably from 0.5 to 3.0 g/m2.
11. Medium according to claim 1 in which the overlayer comprises further at least one fluoro -surfactant, preferably a fluoro -surfactant selected from the group of Li, K and Na- N-perfluoro C4-C13 alkane sulfonyl -N- alkyl glycine, 1,4-bis (fluoroalkyl)-2-[2-N,N,N-trialkylammonium) alkyl amino] butanedioate, and fluorosurfactants having the chemical structure of RfCH2CH2SCH2CH2CO2Li or RfCH2CH2θ(CH2CH2O)χH wherein Rf = F(CF2CF2)3-8 and x = 0 to 25.
12. Medium according to claim 11, wherein the amount of fluorosurfactant is from 2.5 to 250 mg/m2.
13. Medium according to any of the previous claims, wherein the underlayer(s) comprises further a mixture of gelatin and water soluble polymer with a weight ratio which varies from 12:1 to 1:1.
14. Medium according to claim 13 wherein said water soluble polymer is selected from the group of polyvinyl alcohol (PVA) -based polymers, cellulose derivatives, polyethylene oxide, poly aery lamide, polyvinylpyrollidone or mixtures thereof.
15. Medium according to claim 14, wherein said PVA-based polymer is selected from the group consisting of fully hydrolysed or partially hydrolysed polyvinyl alcohol, carboxylated PVA, acetoacetylated PVA, quaternary ammonium modified PVA, copolymers and terpolymers of PVA with other polymers such as a PVA-NVF polymer according to formula I:
Figure imgf000035_0001
(I) wherein n is between 0 and about 20 mole percent; m is between about 50 and about 97 mole percent; x is between 0 and about 20 mole percent; y is between 0 and about 20 mole percent; z is between 0 and about 2 mole percent and x+y is between about 3 and about 20 mole percent; Ri, and R3 are independently H, 3-propionic acid or Ci-Ce alkyl ester thereof, or is 2-methyl-3-propionic acid or Ci-Ce alkyl ester thereof; and R2 and R4 are independently H or CI-CG alkyl.
16. Medium according to claim 12 or wherein the amount of said gelatin is from 1 to 30 g/m 2, preferably from 2 to 20 g/m2 and the amount of said water soluble polymer is from 0.1 to 30 g/m2, preferably from 0.2 to 20 g/m2.
17. Medium according to any one of the previous claims, wherein the support is selected from a paper, a base paper,- a pigment coated base paper, a laminated pigment coated base paper, a laminated paper, a synthetic paper or a film support.
18. Medium according to any one of the previous claims, wherein the support has a surface roughness Ra smaller than 1.0 μm, preferably smaller than 0.8 μm.
19. Process for producing a recording medium, comprising the steps of: a. preparation of at least one aqueous mixture comprising at least a modified gelatin for the overlayer; and b. preparation of one or more homogeneous aqueous mixtures for one or more underlayers; c. preparation of an oil-in water emulsion comprising one or more hydrophobic UV agents dissolved in a high boiling organic solvent and optionally in the presence of a low boiling organic co -solvent, or preparation of a dispersion comprising one or more hydrophobic UN agents in a hydrophilic solvent, d. mixing said oil-in-water emulsion or said dispersion with at least one of said mixtures for the underlayers or the overlayer to give a homogenous emulsion, e. coating said mixtures consecutively or simultaneously on a support, followed by drying the coated support
20. A method of forming a permanent, precise ink -jet image comprising the steps of: providing an ink -jet recording medium as defined in any of the claims 1- 18; and bringing ink -jet ink into contact with the medium in the pattern of a desired image.
PCT/NL2004/000692 2003-10-03 2004-10-04 Recording medium WO2005032835A1 (en)

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Citations (10)

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Publication number Priority date Publication date Assignee Title
GB2088777A (en) 1980-10-28 1982-06-16 Fuji Photo Film Co Ltd Ink jet image-forming process
US4833172A (en) 1987-04-24 1989-05-23 Ppg Industries, Inc. Stretched microporous material
US4861644A (en) 1987-04-24 1989-08-29 Ppg Industries, Inc. Printed microporous material
US4926190A (en) 1987-02-18 1990-05-15 Ciba-Geigy Corporation Ink jet recording process using certain benzotriazole derivatives as light stabilizers
US5326391A (en) 1992-11-18 1994-07-05 Ppg Industries, Inc. Microporous material exhibiting increased whiteness retention
DE4322178A1 (en) 1993-07-03 1995-01-12 Schoeller Felix Jun Papier Recording sheet for ink jet printing processes
EP0738718A1 (en) 1995-04-19 1996-10-23 Ciba-Geigy Ag 2-(2-Hydroxy-3-alpha-cumyl-5-alkylphenyl)-2h-benzotriazoles useful as light stabilisers
US5624743A (en) * 1996-02-26 1997-04-29 Xerox Corporation Ink jet transparencies
EP0806299A2 (en) 1996-05-09 1997-11-12 Felix Schoeller jr Foto- und Spezialpapiere GmbH & Co. KG Recording material for the ink jet printing process
US20030152751A1 (en) * 2001-10-31 2003-08-14 Eastman Kodak Company Ink jet recording element

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2088777A (en) 1980-10-28 1982-06-16 Fuji Photo Film Co Ltd Ink jet image-forming process
US4926190A (en) 1987-02-18 1990-05-15 Ciba-Geigy Corporation Ink jet recording process using certain benzotriazole derivatives as light stabilizers
US4833172A (en) 1987-04-24 1989-05-23 Ppg Industries, Inc. Stretched microporous material
US4861644A (en) 1987-04-24 1989-08-29 Ppg Industries, Inc. Printed microporous material
US5326391A (en) 1992-11-18 1994-07-05 Ppg Industries, Inc. Microporous material exhibiting increased whiteness retention
DE4322178A1 (en) 1993-07-03 1995-01-12 Schoeller Felix Jun Papier Recording sheet for ink jet printing processes
EP0738718A1 (en) 1995-04-19 1996-10-23 Ciba-Geigy Ag 2-(2-Hydroxy-3-alpha-cumyl-5-alkylphenyl)-2h-benzotriazoles useful as light stabilisers
US5624743A (en) * 1996-02-26 1997-04-29 Xerox Corporation Ink jet transparencies
EP0806299A2 (en) 1996-05-09 1997-11-12 Felix Schoeller jr Foto- und Spezialpapiere GmbH & Co. KG Recording material for the ink jet printing process
US20030152751A1 (en) * 2001-10-31 2003-08-14 Eastman Kodak Company Ink jet recording element

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