EP2703092A1 - Method for adjusting various shine levels of radiation cured varnishes and use of same - Google Patents

Abstract

The method involves providing a coating formulation comprising a UV-curable binder, a reactive diluent and a photo-initiator in a layer having preset thickness. The coating formulation is transported on a conveyor system with a belt speed under suspension of short-wave UV radiation by a radiation source. The gloss levels of obtained coatings are measured. The correlation curve is created by plotting the short-wave UV radiation dose to the degree of gloss. The desired gloss level is selected and the necessary short-wave UV radiation dose is determined using the correlation curve.

Description

The invention relates to a method for setting different degrees of gloss in radiation-cured paints, the resulting radiation-cured paints with different degrees of gloss, suitable radiation-curable coating formulations, and the use of the resulting paints for modifying, e.g. Coating or gradual matting of surfaces of substrates such as plastic sheets or foils, in particular polycarbonate and / or polyester sheets or sheets.

For paints, e.g. protect the surfaces of optoelectronic components such as displays, an anti-glare effect is required at the same time high transparency. Anti-glare means that a punctiform beam of light striking the front of a surface of, for example, a display, rather than being reflected as such, is scattered back in various directions to prevent dazzling of the display user. Furthermore, lacquers have the task not only to protect surfaces but also to design, so there are requirements for a certain degree of gloss for certain design applications. As an example decorative foils are mentioned, which are used, inter alia, in the furniture industry but also in the vehicle interior.

In order to set a certain degree of gloss, for example, a specific structure can be imprinted on the surface of a substrate or of a lacquer applied thereon by means of a textured roller. Disadvantage of this technique is that usually only a single gloss value or a very narrow range can be realized by a roller and you needed many different rollers for different gloss levels that are expensive to manufacture.

Another approach is to adjust the gloss level based on a self-assembly of the surface structure of the paint formulation. For this purpose, a radiation-induced folding of a wet paint by short-wave ultraviolet (UV) radiation is an option, which can be cured in a subsequent step. Short-wave UV or vacuum UV (VUV) radiation is used in paint curing to obtain hard, highly cross-linked, chemical-resistant surfaces. As is known to the person skilled in the art, the VUV radiation effects a microplating of the surface and thus matting of the surface to typically 5 to 25 highlights. It is true that with increasing the radiation dose, a stronger microfolding and thus a higher matting of the paint surface are obtained becomes. DE 10 2006 042 063 A1 describes a method for adjusting the degree of gloss and the feel of surfaces of radiation-curable paints and lacquers by photochemical microfilling using short-wavelength monochromatic UV radiation. A However, the degree of gloss is adjusted exclusively by varying the residence time between the beginning of folding (short-wave UV radiation) and completion by complete curing by means of long-wave UV radiation. For this purpose, the belt speed or the distance between the two radiation sources is varied. The coatings generally UV-curable formulations based on acrylates, methacrylates, vinyl ethers, epoxies, styrene or the like are described in layer thicknesses greater than or equal to 30 microns.

DE 10 207 401 A1 relates to an organosilicon nano- and / or microhybrid capsule-containing composition for scratch- or abrasion-resistant coatings, wherein the organosilicon nano- or micro-hybrid system consists of small metal oxide cores A and a substantially complete, organosilicon sheath B, the method for producing an organosilicon nano - And / or microhybrid capsules containing pasty composition and the use of these for the production of paint for producing a scratch and abrasion resistant coating on a substrate. The influence of the surface gloss is not the subject of the disclosure.

It thus turns out, starting from the known state of the art, the object to provide an industrially applicable, efficient method for adjusting the gloss of radiation-cured coatings, suitable for this purpose, radiation-curable coating formulations, and their use for the surface modification of substrates.

• a) Bereitstellung einer Lackformulierung enthaltend mindestens zwei UV-härtbare Bindemittel, einen Reaktivverdünner und einen Fotoinitiator in einer Schichtdicke von 2-20 µm, mit einer Viskosität von größer 1 bis 54 Pa s,
• b) Transportieren der Lackformulierung auf einer Bandanlage mit einer Bandgeschwindigkeit unter Aussetzung von kurzwelliger UV Strahlung (VUV) durch mindestens eine Strahlungsquelle und anschließend längerwelliger UV-Strahlung, bei gezielter Variation der kurzwelligen UV Strahlungsintensität über die Anzahl der Strahlungsquellen, die Eingangs-Stromstärke, die Signalstärke der Strahlungsquelle(n) oder über Blenden zwischen Strahlungsquelle und Lackformulierung,
• c) Messung der Glanzgrade der erhaltenen Lacke und
• d) Erstellung einer Korrelationskurve durch Auftragung der kurzwelligen UV Strahlendosis gegen den Glanzgrad
• e) optional mindestens einmalige Wiederholung der vorangehenden Schritte unter Variation eines Parameters
• f) Wahl des gewünschten Glanzgrades und Ermitteln der dafür notwendigen kurzwelligen UV Strahlendosis mit Hilfe der erstellten Korrelationskurve(n).

The invention therefore provides a method for the gradual adjustment of the gloss level of a radiation-curable lacquer using a correlation curve comprising the steps

• a) providing a paint formulation comprising at least two UV-curable binders, a reactive diluent and a photoinitiator in a layer thickness of 2-20 μm, having a viscosity of greater than 1 to 54 Pa s,
• b) transporting the paint formulation on a belt system at a belt speed with exposure to short-wave UV radiation (VUV) by at least one radiation source and then longer-wave UV radiation, with specific variation of the short-wave UV radiation intensity via the number of radiation sources, the input current intensity, the signal intensity of the radiation source (s) or via diaphragms between the radiation source and the paint formulation,
• c) Measurement of the gloss levels of the resulting lacquers and
• d) Creation of a correlation curve by plotting the short-wave UV radiation dose against the gloss level
• e) optionally at least one repetition of the preceding steps with variation of a parameter
• f) Choice of the desired degree of gloss and determination of the necessary short-wave UV radiation dose with the help of the created correlation curve (s).

It has been found that in addition to the residence times between short-wave and long-wave UV radiation, the radiation dose of the short-wave UV radiation source is of crucial importance for setting the gloss level. A clear correlation between these parameters and the achieved gloss levels could be shown. Surprisingly and unexpectedly for the expert it was found that the gloss level increases with increasing short-wave UV radiation dose.

The UV radiation dose, hereinafter referred to as the short-wave UV radiation dose, describes the energy input to the irradiation surface and is the product of radiation intensity of the radiation source and the irradiation duration, which is given by the belt speed. $$\mathrm{radiation\; dose}\left[\mathrm{mJ}/\mathrm{cm}\mathrm{2}\right]=\mathrm{radiation\; intensity}\ddot{\mathrm{a}}\mathrm{t}\left[\mathrm{mW}/\mathrm{cm}\mathrm{2}\right]\mathrm{x\; time}\left[\mathrm{s}\right]$$

Unlike in DE 10 2006 042 063 A1 In the present invention, the VUV radiation intensity and thus also the radiation dose are controlled by the number of radiation sources, the lamp power of the radiation source (s) via the input current intensity and / or the signal intensity of the radiation source (s) and / or via diaphragms therebetween Varnish varies. In the present invention, the gloss level increases with increasing short-wave UV radiation dose. This means that the setting of the gloss level is not as in DE 10 2006 042 063 A1 described based on the termination of the initiated by the short-wave UV radiation micro-folding process by means of premature curing by the long-wave UV radiation. In order to achieve this according to the invention, the belt speed must be correspondingly low, or else the distance between the short-wave radiation source (s) and the long-wave radiation source be large enough, so the reaction time after receiving the short-wave UV radiation dose be sufficiently large. This is adjustable by the skilled person.

Under VUV light is understood light of a wavelength of about 100 - 200 nm according to DIN 5031-7: 1984-01 (DIN 5031, Part 7, January 1984, radiation physics in the optical field and lighting technology, naming the wavelength ranges).

According to the invention, UV light of the wavelength of ≥ 120 nm to ≦ 230 nm, preferably of ≥ 150 nm to ≦ 225 nm, particularly preferably of 172 nm, is irradiated.

Radiation sources suitable according to the invention are excimer UV lamps which emit UV light in the range from ≥ 120 nm to ≦ 230 nm, preferably from ≥ 150 nm to ≦ 225 nm, particularly preferably 172 nm. For example, suitable are hydrogen (H ₂ ) excimer lamps with 123 and 116 nm emission wavelength, argon (Ar ₂ ) excimer lamps with 126 nm emission wavelength, fluorine (F ₂ ) excimer lamps with 157 nm emission wavelength, xenon -Excimer lamps with an emission wavelength of 172 nm, argon fluoride (ArF) -explex lamps with 193 nm emission wavelength or krypton chloride (KrCl) with 222 nm emission wavelength (Lit .: Arnold F. Holleman, Egon Wiberg, Nils Wiberg: Textbook of Inorganic Chemistry, 101st Edition. deGruyter, 1995, p. 869 ). Preference is given to the use of at least one xenon excimer lamp with an emission wavelength of 172 nm. The radiation dose can be further increased, especially at high belt speeds, by means of a plurality of lamps connected in series. Preferred radiation doses are those from 0 to 60 mJ / cm ² , more preferably from 0 to 55 mJ / cm, 0.3 to 50.8 mJ / cm ² for at least two lamps and those from 0 to 35 mJ / cm ² from 0 to 25, more preferably from 0 to 15 mJ / cm ² for at least one lamp.

Irradiation under short-wave UV light must be performed under an oxygen-depleted atmosphere or with complete exclusion of oxygen, i. under an inert gas atmosphere. The irradiation is particularly preferably carried out under short-wave UV light under an inert gas atmosphere. Inert gas is understood to mean a gas which, under the curing conditions used, is not decomposed by the short-wave UV radiation, does not inhibit the curing and does not react with the applied coating compositions according to the invention. Preferably, nitrogen, carbon dioxide, combustion gases, helium, neon or argon, more preferably nitrogen are used.

This nitrogen should contain only minimal amounts of foreign gases such as oxygen. Purity grades of <300 ppm oxygen are preferably used.

The final curing of the short-wave pre-irradiated paint formulation is effected by means of actinic radiation such as UV radiation, in particular in comparison to the short-wave UV radiation of longer-wave UV radiation, such as UVC radiation. Preference is given to UV radiation in the wavelength range from ≥ 200 nm to ≦ 420 nm, preferably from ≥ 240 nm to ≦ 420 nm at a radiation dose of 80 to 4000 mJ / cm ² , preferably from 200 to 2000 J / cm ² , more preferably from 550 to 1000 mJ / cm ² . In particular, high and medium pressure mercury lamps are used as UV radiation sources, whereby the mercury vapor may be doped with further elements such as gallium or iron. Furthermore, UV-emitting LEDs, laser-pulsed lamps known as UV flashlamps, are suitable.

The irradiation may optionally also in the absence of oxygen, for. B. under inert gas atmosphere or oxygen-reduced atmosphere.

In one embodiment of the method according to the invention, the curing by means of longer-wave UV radiation in the wavelength range of ≥ 200 nm to ≤ 420 nm, preferably from ≥ 240 nm to ≤ 420 nm at a radiation dose of 80 to 4000 mJ / cm ² , preferably from 200 to 2000 mJ / cm ² , more preferably from 550 to 1000 mJ / cm ² . The radiation dose is 80 to 4000 mJ / cm ² , preferably from 80 to 2000 mJ / cm ² , more preferably from 80 to 600 mJ / cm ² .

The determination of the short-wave UV radiation dose is carried out by means of methods known to the person skilled in the art, for example ozonolysis dosimetry.

It turns out that not all radiation-curable coating formulations are equally suitable for the process according to the invention. The formulation according to usable paint formulations was therefore also an object of the invention.

• a) mindestens zwei strahlenhärtbare Bindemittel
• b) mindestens einen Reaktivverdünner,
• c) mindestens einen Photoinitiator
• d) gegebenenfalls Additive, Lichtschutzmittel, Stabilisatoren etc.
• e) gegebenenfalls Pigmente
• f) gegebenenfalls weitere Füllstoffe
• g) gegebenenfalls Lösemittel
• h) gegebenenfalls Nanopartikel

und weisen eine Viskosität von größer 1 bis 54 Pa s, bevorzugt von 5 bis 50 Pa s auf.Suitable radiation-curable coating compositions for step (1) included

• a) at least two radiation-curable binder
• b) at least one reactive diluent,
• c) at least one photoinitiator
• d) optionally additives, light stabilizers, stabilizers, etc.
• e) optionally pigments
• f) optionally further fillers
• g) optionally solvents
• h) optionally nanoparticles

and have a viscosity of greater than 1 to 54 Pa s, preferably from 5 to 50 Pa s.

Suitable binders according to a) are polymers and / or oligomers which contain at least one, in particular at least two double bonds activatable with UV radiation. These polymers and / or oligomers usually have a number average molecular weight of from 250 to 50,000 g / mol, preferably from 500 to 25,000 g / mol, in particular from 700 to 5,000 g / mol. Preferably, they have a double bond equivalent weight of 100 to 4000 g / mol, more preferably from 300 to 2000 g / mol. Preferably, they are used in an amount of 5 to 99 wt .-%, preferably 10 to 90 wt .-%, particularly preferably 20 to 80 wt .-%, each based on the solids content of the coating compositions of the invention. The determination of the number average molecular weight of the binder is carried out by means of gel permeation chromatography using polystyrene as standard and tetrahydrofuran as the mobile phase.

"(Meth) acrylate" in the context of this invention refers to corresponding acrylate or methacrylate functions or to a mixture of both.

Examples of suitable radiation-curable binders originate from the oligomer and / or polymer classes of (meth) acryl-functional (meth) acrylic copolymers, polyether (meth) acrylates, polyester (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates, amino ( meth) acrylates, melamine (meth) acrylates, silicon (meth) acrylates and phosphazene (meth) acrylates. Binders which are free of aromatic structural units are preferably used. Preference is given to using urethane (meth) acrylates, phosphazene (meth) acrylates and / or polyester (meth) acrylates, more preferably urethane (meth) acrylates, very particularly preferably aliphatic urethane (meth) acrylates.

To reduce the viscosity, low molecular weight double bond-containing monomers, so-called reactive diluents b), can be added to the binders described above.

As reactive diluents b) it is possible to use compounds which likewise (co) polymerize during radiation curing and are thus incorporated into the polymer network. Suitable reactive diluents b) containing at least one, in particular at least two, with UV radiation containable bond (s) are olefinically unsaturated monomers, preferably vinyl aromatic monomers and acrylates, in particular acrylates, having at least one free-radically polymerizable double bond and preferably having at least two free-radically polymerizable double bonds. Suitable reactive diluents are discussed in detail Rompp Lexikon Lacke and printing inks, Georg Thieme publishing house, Stuttgart, New York, 1998 "reactive diluents", pages 491 and 492 described.

By way of example, esters of acrylic acid or methacrylic acid, preferably of acrylic acid with monofunctional or polyfunctional alcohols, may be mentioned as reactive diluents. Suitable alcohols are, for example, the isomeric butanols, pentanols, hexanols, heptanols, octanols, nonanols and decanols, furthermore cycloaliphatic alcohols such as isobornol, cyclohexanol and alkylated cyclohexanols, dicyclopentanol, arylaliphatic alcohols such as phenoxyethanol and nonylphenylethanol, and tetrahydrofurfuryl alcohols. Furthermore, alkoxylated derivatives of these alcohols can be used. Suitable dihydric alcohols are, for example, alcohols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, the isomeric butanediols, neopentyl glycol, 1,6-hexanediol, 2-ethylhexanediol and tripropylene glycol or alkoxylated derivatives of these alcohols. Preferred dihydric alcohols are 1,6-hexanediol, dipropylene glycol and tripropylene glycol. Suitable trihydric alcohols are glycerol or trimethylolpropane or their alkoxylated derivatives. Quaternary alcohols are pentaerythritol or its alkoxylated derivatives. A suitable hexahydric alcohol is dipentaerythritol or its alkoxylated derivatives. Particularly preferred are the alkoxylated derivatives of said dihydric to hexahydric alcohols.

The coating compositions according to the invention comprise one or more photoinitiators c). The photoinitiator is formed by high-energy electromagnetic radiation, such as visible light or, in particular, UV radiation, e.g. Light of the wavelength 200 to 700 nm or by irradiation with high-energy electrons (electron radiation) activates and thereby initiates the polymerization via the UV radiation-activatable groups contained in the coating compositions according to the invention.

Preferably, the photoinitiator is selected from the group consisting of unimolecular (type I) and bimolecular (type II) photoinitiators. Suitable photoinitiators of type I are aromatic ketone compounds such as benzophenones in combination with tertiary amines, alkylbenzophenones, 4,4'-bis (dimethylamino) benzophenone (Michler's ketone), anthrone and halogenated benzophenones or mixtures of the types mentioned. As photoinitiators type II For example, benzoins, benzoin derivatives, especially benzoin ethers, benzil ketals, acylphosphine oxides, especially 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bisacylphosphine oxides, phenylglyoxylic acid esters, camphorquinone, □ aminoalkylphenones, □□, □ dialkoxyacetophenones and □ -hydroxyalkylphenones, are suitable.

The coating compositions may contain additives d). Examples of suitable additives are light stabilizers, such as UV absorbers and reversible free-radical scavengers (HALS), antioxidants, deaerating agents, wetting agents, emulsifiers, slip additives, polymerization inhibitors, adhesion promoters, leveling agents, film-forming auxiliaries, rheology aids, such as thickeners and pseudo-so-called "sag control agents" (SCA ), Flame retardants, corrosion inhibitors, waxes, siccatives and biocides.

These and other suitable ingredients are used in the Textbook »Paint Additives« by Johan Bieleman, Wiley-VCH, Weinheim, New York, 1998 , in D. Stoye and W. Freitag (Editors), "Paints, Coatings and Solvents", Second, Completely Revised Edition, Wiley-VCH, Weinheim, New York, 1998 , »14.9. Solvent Groups, pages 327 to 373 , described.

The coating compositions may also be pigmented according to e). Preferably, they then contain at least one pigment selected from the group consisting of organic and inorganic, transparent and opaque, color and / or effect as well as electrically conductive pigments. Suitable pigments e) and fillers f) are described, for example, in Lückert, Pigments and Filler Tables, Poppdruck, Langenhagen, 1994 ,

Optionally, solvents g) can be added to the coating compositions. Suitable solvents are inert to the functional groups present on the coating agent from the time of addition to the end of the process. Suitable are e.g. solvents used in paint technology, such as hydrocarbons, alcohols, ketones and esters, e.g. Toluene, xylene, isooctane, acetone, butanone, methyl isobutyl ketone, ethyl acetate, butyl acetate, tetrahydrofuran, N-methylpyrrolidone, dimethylacetamide, dimethylformamide.

In a further embodiment of the invention, the coating formulations also contain nanoparticles h), preferably ceramic nanoparticles. Suitable nanoparticles are z. For example, silica or organosilicon nano and / or microhybrid capsules having an inorganic core and an organic shell, such as described in DE 10 207 401 A1 , Alternatively, urea-methanal condensates or mixtures based on polyamide 12 can be used. According to the invention, nanoparticles are used in amounts of from 0.1 to 15% by weight, preferably from 2 to 12% by weight, particularly preferably 3 to 10% by weight is used. The ceramic nanoparticles, with which the degree of gloss can be adjusted over a particularly wide range, are introduced unmodified into the formulation for smaller concentrations, such as, for example, 3% by weight, and form a stable suspension. Only for a composition with a nanoparticle content of greater than or equal to 10% by weight of silanized particles according to DE 10 207 401 A1 used to ensure the stability of the suspension.

According to the invention, the coating composition is applied to a suitable substrate by methods known to those skilled in the art. The coating composition is applied to the substrate in layer thicknesses of ≥ 2 μm to < 20 μm, preferably 3 μm to ≦ 15 μm, particularly preferably 5 μm to ≥ 12 μm.

Suitable substrates for the process according to the invention are, for example, mineral substrates, wood, wood-based materials, metal, fiber-bonded materials or plastic.

A substrate according to the invention of the paint is, in one embodiment of the invention, a plastic, in particular a plastic sheet or film, of a thermoplastic polymer, for example polyamides (PA), polylactate (PLA), polyacrylate, polymethyl methacrylate (PMMA), polycarbonate (PC) , Polyesters such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), cycloolefin copolymers (COC), polystyrene (PS), polysulfones, polyetheretherketone (PEEK) and polyvinyl chloride (PVC).

Suitable polycarbonates for the preparation of the substrates according to the invention are all known polycarbonates. These are homopolycarbonates, copolycarbonates and thermoplastic polyestercarbonates. Preferred is a polycarbonate sheet or film, a polyester sheet or film, or a coextruded polycarbonate / polyester sheet or film

The suitable polycarbonates preferably have average molecular weights Mw of from 18,000 to 40,000, preferably from 26,000 to 36,000 and in particular from 28,000 to 35,000, determined by measuring the relative solution viscosity in dichloromethane or in mixtures of equal amounts by weight phenol / o-dichlorobenzene calibrated by light scattering.

The polycarbonates are preferably prepared by the phase boundary process or the melt transesterification process and will be described below by way of example using the phase boundary process.

The preparation of the polycarbonates takes place, inter alia, according to the phase boundary process. This process for polycarbonate synthesis has been widely described in the literature; be exemplary on H. Schnell, Chemistry and Physics of Polycarbonates, Polymer Reviews, Vol. 9, Interscience Publishers, New York 1964 p. 33 et seq. , on Polymer Reviews, Vol. 10, "Condensation Polymers by Interfacial and Solution Methods", Paul W. Morgan, Interscience Publishers, New York 1965, Ch. VIII, p. 325 , on Dres. U. Grigo, K. Kircher and P. R-Müller "Polycarbonates" in Becker / Braun, Kunststoff-Handbuch, Volume 3/1, polycarbonates, polyacetals, polyesters, cellulose esters, Carl Hanser Verlag Munich, Vienna 1992, p. 118-145 as well as on EP-A 0 517 044 directed.

Suitable diphenols are for example in the US Pat. No. 2,999,835 . 3 148 172 . 2 991 273 . 3 271 367 . 4 982 014 and 2,999,846 , in the German publications 1 570 703 . 2 063 050 . 2 036 052 . 2 211 956 and 3,832,396 , the French patent 1 561 518 in the monograph " H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964, p28ff; S.102ff " , and in " DG Legrand, JT Bendler, Handbook of Polycarbonates Science and Technology, Marcel Dekker New York 2000, p. 72ff . "described.

The production of polycarbonates is also possible from diaryl carbonates and diphenols according to the known polycarbonate process in the melt, the so-called melt transesterification process, which is described, for example, in US Pat WO-A 01/05866 and WO-A 01/05867 is described. In addition, transesterification (acetate and Phenylesterverfahren), for example, in the US-A 34 94 885 . 43 86 186 . 46 61 580 . 46 80 371 and 46 80 372 , in the EP-A 26 120 . 26 121 . 26 684 . 28 030 . 39,845 . 39,845 . 91 602 . 97 970 . 79 075 . 14 68 87 . 15 61 03 . 23 49 13 and 24 03 01 as well as in the DE-A 14 95 626 and 22 32 977 described.

Both homopolycarbonates and copolycarbonates are suitable. For the preparation of copolycarbonates according to the invention as component A, it is also possible to use from 1 to 25% by weight, preferably from 2.5 to 25% by weight (based on the total amount of diphenols to be used) of hydroxyl-aryloxy endblocked polydiorganosiloxanes. These are known (see, for example, from U.S. Patent 3,419,634 ) or produced by literature methods. The preparation of polydiorganosiloxane-containing copolycarbonates is z. In DE-OS 33 34 782 described.

Further, polyester carbonates and block copolyestercarbonates are suitable, especially as described in the WO 2000/26275 are described. Aromatic dicarboxylic acid dihalides for the preparation of aromatic polyester carbonates are preferably the diacid dichlorides of isophthalic acid, terephthalic acid, diphenyl ether-4,4'-dicarboxylic acid and naphthalene-2,6-dicarboxylic acid.

The aromatic polyester carbonates may be both linear and branched in a known manner (see also DE-OS 29 40 024 and DE-OS 30 07 934 ).

The polydiorganosiloxane-polycarbonate block polymers may also be a blend of polydiorganosiloxane-polycarbonate block copolymers with conventional polysiloxane-free thermoplastic polycarbonates, the total content of polydiorganosiloxane structural units in this blend being about 2.5 to 25 weight percent.

Such polydiorganosiloxane-polycarbonate block copolymers are, for example U.S. Patent 3,189,662 . U.S. Patent 3,821,325 and U.S. Patent 3,832,419 known.

Preferred polydiorganosiloxane-polycarbonate block copolymers are prepared by reacting alpha, omega-Bishydroxyaryloxyendgruppen-containing polydiorganosiloxanes together with other diphenols, optionally with the use of branching agents in the usual amounts, for. B. by the two-phase interface method (see H. Schnell, Chemistry and Physics of Polycarbonate Polymer Rev. Vol. IX, page 27 et seq., Interscience Publishers New York 1964 ), wherein in each case the ratio of the bifunctional phenolic reactants is chosen so that it results in the inventive content of aromatic carbonate structural units and diorganosiloxy units.

Such alpha, omega-Bishydroxyaryloxyendgruppenhaltige polydiorganosiloxanes are for example US 3 419 634 known.

The thermoplastic polymers may contain anti-aging agents that substantially increase stability. To modify the products of the invention substances such. As carbon black, diatomaceous earth, kaolin, clays, CaF ₂ , CaCO ₃ , aluminum oxides, glass fibers and inorganic pigments are added both as fillers and as a nucleating agent.

In a further embodiment of the invention, the plastic sheets or foils are transparent.

Suitable plastics for transparent sheets or films according to the invention are all transparent thermoplastics: polyacrylates, polymethyl methacrylates (PMMA, Plexiglas® from Röhm), cycloolefin copolymers (COC, Topas® from Ticona); Zenoex® from Nippon Zeon or Apel® from Japan Synthetic Rubber), polysulfones (Ultrason® from BASF or Udel® from Solvay), polyesters such as PET or PEN, polycarbonate, polycarbonate / Polyester blends, eg PC / PET, polycarbonate / polycyclohexylmethanol cyclohexanedicarboxylate (PCCD, Xylecs® from GE) and polycarbonate / polybutylene terephthalate (PBT) blends.

Preference is given to using polycarbonates, polyesters or coextruded polycarbonate / polyester.

The adhesion or adhesion of the hardened lacquer to the substrate must have a cross hatch value of 0 according to DIN EN ISO 2409: 2007.

The level of the VUV radiation dose is determined by the rate of passage of the wet paint formulation below the radiation source (s), ie the belt speed, and by the intensity of the radiation sources.

In a preferred embodiment of the invention, the belt speed is kept constant and the UV radiation intensity and thus the UV radiation dose is gradually increased. If the tape speed is kept constant as an influencing parameter, an increase of the short-wave UV radiation dose for the paint formulations according to the invention at all belt speeds (2.5-20 m / min and a doubling per step) results in an approximately linear increase in the gloss level up to one the respective paint formulation individually different, maximum value. The plot of the short-wave UV radiation dose against the gloss level obtained gives the correlation curve. As the belt speed increases, the slope m of the correlation curves increases steadily (s. Fig. 1 and 2 and examples).

This makes it possible to read off the required short-wave UV radiation doses and the associated belt speed on the basis of the correlation curve for a particular paint formulation in order to set the desired gloss level for the resulting paint according to the invention.

In another embodiment of the invention, by incorporating ceramic nanoparticles into the lacquer formulation, such as silica nanoparticles in Examples 2, 3 and silanated in Example 4, both the gloss level range is extended to as many as 120 gloss points and the surface quality, such as e.g. the abrasion resistance improved with increased gloss.

In a further embodiment of the invention, an array with at least two Xe ₂ excimer lamps is installed. In one embodiment, only the power of the at least first lamp is varied between 10 and 100% and the power of the at least second lamp is 100 % constant. Furthermore, the variation of the short-wave UV radiation dose is achieved by means of apertures with openings of 10% - 80%.

Known coating processes by means of applicators and / or squeegees do not match either a roll-to-roll process or the individual surface quality produced is satisfactory. Furthermore, the layer thickness is comparatively high and varies on a test piece in a wide range. According to the invention, therefore, the coating method is adapted to the technical conditions of a continuous roll-to-roll process and a Farbandruckgerät used for coating, so for example, a 3 × 18 cm ² large test piece with a layer thickness of 2-10 microns by a contact pressure 100 N. at a temperature = RT (of 22 ° C) and a contact time less than 1 min created. The color proofing apparatus used is a printability tester "Printability Tester for Offset Inks" C1 Series 425.1 V 1995 from IGT.

A belt system to be used according to the invention is known to a person skilled in the art. According to the invention, the irradiation of the wet paint is carried out on a belt system operated with nitrogen.

The inventive setting of the gloss level is not based as in DE 10 2006 042 063 A1 described on the termination of the short-wave UV-initiated micro-folding process by means of premature curing by the long-wave UV radiation. In order to achieve this according to the invention, the reaction time after application of the short-wave UV radiation dose must be sufficiently high, ie the belt speed must be sufficiently low or the distance between the short-wave radiation source (s) and the longer-wave radiation source must be large enough. This is basically adjustable by a person skilled in the art, preferably a distance of 80 cm between VUV and UV radiation sources in the exemplified system at belt speeds of 2.5 to 20 m / min and short-wave UV radiation doses of 0 to 60 mJ / cm ² .

A likewise variation of the method according to the invention is the keeping constant of the VUV radiation dose with variation of the belt speed and radiation source intensity for the adjustment of the gloss levels. Again, it must be ensured that the reaction time after application of the short-wave UV radiation dose is sufficiently large.

In a preferred embodiment of the invention, the substrate coated with wet coating formulation is removed in the oven to homogenize the surface prior to irradiation. At temperatures of 40-80 ° C, preferably 50-70 ° C, more preferably 60 ° C for a period of 5 to 60 minutes, preferably 20 minutes, the surface is homogenized.

The gloss is measured in accordance with the provisions of DIN 67 530: 1982, DIN ISO 2813: 1999, ASTM D 523-08 and D 2457-08. The degree of gloss is measured at a test angle of 60 °.

The lacquer obtained by the process according to the invention also has an advantageously high contact transparency. Furthermore, the resulting paint surfaces show good resistance to solvents (one minute with solvent vapors such as alcohols, acetates and aromatic solvents with a layer thickness of 4 microns). A satisfactory solvent resistance even against ketones such as acetone is achieved at layer thicknesses of 10 microns.

Substrates equipped with a specific degree of gloss according to the invention can be used according to the invention for decorating or designing functional surfaces; be used for equipment of automotive, aircraft, rail vehicle or watercraft interior areas or come for use in or on electrical appliances, preferably household electrical appliances or consumer electronics devices, such as decorative films or display foils. A preferred use is as an antiglare film for e.g. Displays, touchscreens or photovoltaic cells.

Also conceivable is the use of substrates in furniture construction and in the interior trim or in the outer lining of buildings.

The invention is explained in more detail below by way of example with reference to the figures, without, however, restricting them to them.

Fig. 1

die Auftragung der auf die Lackformulierung aus Beispiel 3 angewendete kurzwelligen UV Strahlungsdosis gegen den erhaltenen Glanzwert des fertigen Lacks bei Bestrahlung mit einer Xenon-Excimer-Lampe bei mehreren jeweils konstant gehaltenen Bandgeschwindigkeiten (Korrelationskurven).

Fig. 2

die Auftragung der auf die Lackformulierung aus Beispiel 3 angewendete kurzwelligen UV Strahlungsdosis gegen den erhaltenen Glanzwert des fertigen Lacks bei Bestrahlung mit zwei Xenon-Excimer-Lampen bei mehreren jeweils konstant gehaltenen Bandgeschwindigkeiten (Korrelationskurven).

Show it:

Fig. 1

the application of the applied to the paint formulation of Example 3 short-wave UV radiation dose against the obtained gloss value of the finished paint when irradiated with a xenon excimer lamp at several each held constant tape speeds (correlation curves).

Fig. 2

the application of the applied to the paint formulation of Example 3 short-wave UV radiation dose against the gloss value of the finished paint obtained when irradiated with two xenon excimer lamps at several each held constant tape speeds (correlation curves).

Examples Examples: Used material:

Polycarbonate film:

Makrofol® DE 1-1, thickness 175 or 250 μm

HDDA:

Hexane-1,6-diyl-diacrylate, obtained from BASF SE

Fotoinitator:

Mixture of 2-hydroxy-2-methylpropiophenone (Darocur® DC 1173) and 1-hydroxycyclohexyl-phenyl ketone (Irgacure® 184) in the ratio of 2: 1 (v: v) obtained from Cetelon Nanotechnik GmbH

Aerosil 380:

Silica nanoparticles with a specific surface area of 380 m ² / g, supplied by Evonik Industries AG

Dynasilan VTMO:

bifunctional organosilane purchased from Evonik Industries AG

Desmolux® U 680 H:

Urethane acrylate, 80% in HDDA, M _W about 1400 g / mol, viscosity at 23 ° C about 29 +/- 4 Pa s, reactivity 3.8, obtained from Bayer MaterialScience AG

Desmolux® XP 2740:

Urethane acrylate, 100%, M _W about 1250 g / mol, viscosity at 23 ° C about 8 Pa s, reactivity of 3, purchased from Bayer MaterialScience AG

Genomer® 4316:

Aliphatic polyester urethane-acrylate, 100%, viscosity at 25 ° C about 58 Pa s based on the Rahn AG

maleic anhydride:

purchased from VWR international GmbH

Metoxy-4-anisole:

purchased from VWR international GmbH

Example 1: Adjustment of the gloss value by varying the VUV dose for a paint formulation of Desmolux® U 680 H and Desmolux® XP 2740 without addition of nanoparticles

The paint formulation consisting of 88.0% by weight of Desmolux® U 680 H, 5% by weight of Desmolux® XP 2740, 5% by weight of HDDA and 2% by weight of photoinitiator was introduced into a vessel and stirred at room temperature with a stirrer at 2500 rpm / min for at least 5 min homogenized. This lacquer was then applied to polycarbonate strips with a dimension of 3 × 18 cm ² using a color proofing device CD Series 425.1 V 1995 from IGT at room temperature in a layer thickness of 2 to 10 μm over an applicator roll with a contact pressure of 100 N. The wet film was immediately exposed in a belt system first short-wave (VUV) and then long-wave UV radiation. As VUV radiation source stood Two xenon excimer lamps with an emission wavelength of 172 nm are permanently installed, which can be controlled independently. Here, for example, the radiation dose of the first xenon excimer lamp was varied while the second was kept constant. In principle, the radiation dose impinging on the substrate can be set by means of the number of lamps, the input current intensity and the signal intensity of the excimer lamp (s) as well as by means of diaphragms between the radiation source and the substrate. In this example, the radiation dose was varied over the input and signal strength of the excimer lamp (s). The dosimeter FlatLog V 1.30 with a VUV sensor from Jenoptik Polymer Systems GmbH was used to determine the dose. The long-wave UV radiation was produced by a Hg amalgam lamp (Print Concept type PC-2-W-1000-1 × 1) with an emission wavelength of 254 nm and an intensity of 550 to 1000 mJ / cm ² . The space around and between the two lamps was cooled and rendered inert by means of a stream of nitrogen. The residual oxygen content was <12 ppm. The distance of the excimer and UV lamps was fixed at 0.8 m in the belt system. In experiments, the dose of short-wave VUV radiation was varied at constant belt speed. In further series of experiments, the variation of the VUV dose was then repeated for other belt speeds. The gloss value of the cured coatings was measured with the gloss meter microTRI-gloss in a daylight box , both from the BYK Additives and Instruments.

Table 1 summarizes the gloss values found as a function of the irradiated VUV dose for different belt speeds. <b> Table 1: </ b> Gloss value as a function of the VUV dose for the paint formulation of Desmolux® U 680 H and Desmolux® XP 2740 without addition of nanoparticles obtained by irradiation with a xenon excimer lamp. tape speed VUV dose Shine at 60 ° [m / min] [mJ / cm ² ] [Highlights] 2.5 2.6 20.1 2.5 6.7 36.0 2.5 13.3 63.8 2.5 20.5 60.7 2.5 25 62.5 2.5 27.8 59.9 5 1.3 17.4 5 3.3 30.3 5 6.6 57.6 5 9.7 59.4 5 12.8 66.4 5 14.5 80.5 10 0.6 17.8 10 1.6 27.8 10 3.6 51.4 10 5.1 67.9 10 6.2 82.2 10 6.8 90.3 20 0.3 19.0 20 0.8 18.4 20 1.7 28.2 20 2.5 34.0 20 3.1 40.4 20 3.6 43.7

Example 2: Adjustment of the gloss value by varying the VUV dose for a paint formulation of Desmolux® U 680 H and Desmolux® XP 2740 with addition of 1% by weight of Aerosil 380

The paint formulation consisting of 87.1% by weight of Desmolux® U 680 H, 4.95% by weight of Desmolux® XP 2740, 4.95% by weight of HDDA and 2% by weight of photoinitiator and 1% by weight of Aerosil 380 was mixed in a Prepared vessel and homogenized at room temperature with a stirrer at 2500 rev / min for at least 5 min. This paint was then applied according to Example 1 on a polycarbonate substrate and the wet paint formulation film was first exposed in a belt plant short-wave (VUV) and then long-wave UV radiation. Table 2 and Table 3 summarize the gloss values found as a function of the irradiated VUV dose for different belt speeds. Table 2: Gloss value as a function of the VUV dose for the paint formulation of Desmolux® U 680 H and Desmolux® XP 2740 with addition of 1% by weight of Aerosil 380, obtained by irradiation with a xenon excimer lamp. tape speed VUV dose Shine at 60 ° [m / min] [mJ / cm ² ] [Highlights] 2.5 2.6 19.9 2.5 6.7 28.3 2.5 13.3 52.1 2.5 20.5 57.1 2.5 25 63.6 2.5 27.8 59.3 5 1.3 18.4 5 3.3 27.7 5 6.6 45.8 5 9.7 61.6 5 12.8 68.1 5 14.5 69.4 10 0.6 19.4 10 1.6 24.3 10 3.6 39.4 10 5.1 51.5 10 6.2 61.2 10 6.8 63.2 20 0.3 18.9 20 0.8 21.5 20 1.7 29.5 20 2.5 36 20 3.1 45.2 20 3.6 49.5 tape speed VUV dose Shine at 60 ° [m / min] [mJ / cm ² ] [Highlights] 10 6.3 37.1 10 7.3 44.6 10 9.3 50.2 10 10.8 81.1 10 11.9 76.8 10 12.5 78 20 2.6 45.8 20 3.1 52 20 4 60 20 4.8 80.3 20 5.4 87.6 20 5.9 94.2

Example 3: Adjustment of the gloss value by varying the VUV radiation dose for a paint formulation of Desmolux® U 680 H and Genomer® 4316 with addition of 1% by weight of Aerosil 380

The paint formulation consisting of 92.85% by weight of Desmolux® U 680 H, 4.85% by weight of Genomer® 4316 and 2% by weight of photoinitiator and 1% by weight of Aerosil 380 was introduced into a vessel and added at room temperature with a stirrer Homogenized at 2500 rpm for at least 5 min. This paint was then applied according to Example 1 on a polycarbonate substrate and the wet paint formulation film was first exposed in a belt plant short-wave (VUV) and then long-wave UV radiation. In Table 4 and 0, the gloss values found are in Dependence of irradiated VUV dose for different tape speeds combined. <b> Table 4: </ b> Gloss value as a function of the VUV dose for the coating formulation of Desmolux® U 680 H and Genomer® 4316 with addition of 1% by weight of Aerosil 380, obtained by irradiation with a xenon excimer lamp , tape speed VUV dose Shine at 60 ° [m / min] [mJ / cm ² ] [Highlights] 2.5 2.6 37.0 2.5 6.7 56.2 2.5 13.3 136.0 2.5 20.5 138.0 2.5 25 140.0 2.5 27.8 152.0 5 1.3 22.9 5 3.3 40.9 5 6.6 68.4 5 9.7 92.4 5 12.8 91.5 5 14.5 106.0 10 0.6 22.2 10 1.6 31.8 10 3.6 55.5 10 5.1 76.9 10 6.2 94.8 10 6.8 104.0 20 0.3 20.8 20 0.8 22.0 20 1.7 38.1 20 2.5 54.8 20 3.1 68.4 20 3.6 74.3 tape speed VUV dose Shine at 60 ° [m / min] [mJ / cm ² ] [Highlights] 2.5 25.6 72.3 2.5 29.7 67.7 2.5 36.3 86 2.5 43.5 113 2.5 48 120 5 12.6 69.7 5 14.6 77.2 5 17.9 93.4 5 21 108 5 24.1 121 5 25.8 123 10 6.3 68.2 10 7.3 77.7 10 9.3 96.8 10 10.8 119 10 11.9 140 10 12.5 140 20 2.6 61.3 20 3.1 75 20 4 100 20 4.8 129 20 5.4 142 20 5.9 154

Example 4: Adjustment of the gloss value by varying the VUV dose for a paint formulation of Desmolux® U 680 H and Desmolux® XP 2740 with addition of 10% by weight of Aerosil 380

The paint formulation consists of 74.71% by weight of Desmolux® U 680 H, 4.24% by weight of Desmolux® XP 2740, 4.24% by weight of HDDA, 4.9% by weight of Dynasilan VTMO, 0.1% by weight. 4-Metoxy-anisole, 0.01% by weight of maleic anhydride, 9.8% by weight of Aerosil 380 and 2% by weight of photoinitiator. First, the liquid coating components were - except the photoinitiator - presented in a vessel and homogenized for 30 min at 60 ° C internal temperature and 1000 U / min (disc diameter 60 mm). Thereafter, the internal temperature was raised to 65 ° C to max. Increased 70 ° C during the reaction and the rotational speed to 500 rev / min. At the beginning of the reaction, about one third of the aerosol A380 was added in portions. Viscosity jumped and the rotational speed was increased stepwise (each at 500 rpm) to 1500 rpm. Subsequently, the remainder of the Aerosil A380 was added in portions within 2 h. It was checked every 15 minutes whether the Aerosil was completely distributed in the reaction matrix during the addition. If not, the remainders were added to the mixture with a spatula. For the 1.5 hour reaction time, both the internal temperature of 65 ° C to max. 70 ° C and held the rotational speed. When the temperature rose above 70 ° C due to the energy input, the rotation speed was decreased to 1000 rpm and the reaction vessel was actively heated to 65 ° C. When the desired temperature corridor was reached, the initial conditions were restored. At the end of the reaction, the highly viscous product was isolated from the reaction vessel by means of a spatula without further work-up steps at 65.degree. The thus obtained nanoparticles highly filled paint was added to the photoinitiator and homogenized at 5000 rev / min for 5 min. Subsequently, the paint was applied according to Example 1 on a polycarbonate substrate and the wet film in a belt system first short-wave (VUV) and then exposed to long-wave UV radiation. Table 6 and Table 7 summarize the gloss values found as a function of the irradiated VUV dose for different belt speeds. <b> Table 6: </ b> gloss value as a function of the VUV dose for the paint formulation of Desmolux® U 680 H and Desmolux® XP 2740 with addition of 10% by weight of Aerosil 380, obtained by irradiation with a xenon excimer Lamp. tape speed VUV dose Shine at 60 ° [m / min] [mJ / cm ² ] [Highlights] 2.5 2.6 27.8 2.5 6.7 54.8 2.5 13.3 81.2 2.5 20.5 105.0 2.5 25 119.0 2.5 27.8 83.6 5 1.3 19.8 5 3.3 34.4 5 6.6 59.4 5 9.7 77.4 5 12.8 104.0 5 14.5 97.0 10 0.6 20.6 10 1.6 26.1 10 3.6 47.0 10 5.1 59.4 10 6.2 69.2 10 6.8 77.6 20 0.3 22.9 20 0.8 22.5 20 1.7 40.4 20 2.5 53.3 20 3.1 67.3 20 3.6 77.9 tape speed VUV dose Shine at 60 ° [m / min] [mJ / cm ² ] [Highlights] 10 6.3 54.2 10 7.3 60.9 10 9.3 68.6 10 10.8 72.7 10 11.9 77.5 10 12.5 129.0 20 3.2 56.9 20 3.7 61.9 20 4.6 79.6 20 5.4 96.0 20 6 112.0 20 6.5 117.0

Claims (17)

A method of gradually adjusting the gloss level of a radiation curable lacquer using a correlation curve comprising the steps a) providing a paint formulation comprising at least two UV-curable binders, a reactive diluent and a photoinitiator in a layer thickness of 2-20 μm, having a viscosity of greater than 1 to 54 Pa s, b) transporting the paint formulation on a belt line with a belt speed under exposure of
short-wave UV radiation (VUV) by at least one radiation source and then longer-wave UVC radiation,
with specific variation of the short-wave UV radiation intensity via the number of radiation sources, the input current intensity, the signal intensity of the radiation source (s) or via diaphragms between the radiation source and the paint formulation, c) Measurement of the gloss levels of the resulting lacquers and d) Creation of a correlation curve by plotting the short-wave UV radiation dose against the gloss level e) optionally at least one repetition of the preceding steps with variation of a parameter f) Choice of the desired degree of gloss and determination of the necessary short-wave UV radiation dose with the help of the created correlation curve (s). Process according to Claim 1, characterized in that the UV-curable binders are at least one urethane acrylate. Process according to Claim 1 or 2, characterized in that the UV-curable binders are at least one aliphatic urethane acrylate. Process according to Claim 3, characterized in that the UV-curable binders are at least two aliphatic urethane acrylates. Method according to one of the preceding claims, characterized in that the belt speed is kept constant. Method according to one of the preceding claims, characterized in that the short-wave UV radiation dose is in a range of 0 to 60 mJ / cm2. Method according to one of the preceding claims, characterized in that the short-wave UV radiation has an emission wavelength of ≥ 120 nm to ≤ 230 nm. Method according to one of the preceding claims, characterized in that the longer-wave UV radiation has an emission wavelength of ≥ 200 nm to ≤ 420 nm. Method according to one of the preceding claims, characterized in that the paint formulation contains ceramic nanoparticles. Method according to one of the preceding claims, characterized in that the paint formulation is applied to a substrate. Method according to claim 10, characterized in that the substrate is a mineral substrate, wood, a wood material, metal, a fiber-bonded material or a plastic. Process according to claims 10 or 11, characterized in that the substrate is a plastic sheet or foil. A method according to any of claims 10-12, characterized in that the substrate is polycarbonate, polyester or coextruded polycarbonate / polyester. Substrate whose degree of gloss of the surface has been modified according to a method of the preceding claims. Use of the substrate according to claim 14 for equipping automobile, aircraft, rail vehicle or watercraft interior areas or for use in or on Electrical appliances, preferably household electrical appliances or consumer electronics. Use of substrates according to claim 14 or 15 as antiglare film for displays, touchscreens or photovoltaic cells Use of substrates according to claims 14 in furniture construction and in the interior trim or in the outer lining of buildings.

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