US3212913A

US3212913A - Adhesive transfers

Info

Publication number: US3212913A
Application number: US444321A
Authority: US
Inventors: Frederick W Mackenzie
Original assignee: Letraset International Ltd
Current assignee: Esselte Pendaflex Corp
Priority date: 1965-03-31
Filing date: 1965-03-31
Publication date: 1965-10-19
Anticipated expiration: 1982-10-19
Also published as: NL280068A; BE619000A

Description

ct. 19, 1965 F, w, MACKENZIE 3,212,913

Ammsrv TRANSFERS original Filed June 19, 1962 FIG. I

5 Hal/P017# Pew Aleman/5277 cia United States Patent O 3,212,913 ADHESIVE TRANSFERS Frederick W. Mackenzie, London, England, assigner to Letraset Limited, London, England, a British company Continuation of application Ser. No. 203,451, June 19, 1962. This application Mar. 31, 1965, Ser, No. 444,321 Claims. (Cl. 117--3.1)

This application is a continuation-in-part of my application Serial No. 286,847 filed lune 10, 1963, copending herewith, now abandoned which is a division of my application Serial No. 118,765 filed June 22, 1961, now U.S. Patent Serial No. 3,131,106 and this application is in addition a continuation of my application Serial No. 203,451 filed lune 19, 1962 and now abandoned.

This invention relates to adhesive transfers (decalcomanias) and more particularly to a form of transfer material in which an image, design or printed matter (hereinafter generally referred to as indicia) may be transferred from a carrier sheet to a further support. The invention includes transfer materials, their production and the processes of their use.

Transfer materials consisting of a carrier sheet carrying an indicia which can be transferred bodily from the carrier sheet to a further support are very well known indeed and a great deal of effort has been directed to the production of such materials which will permit transfer, in close register, of any indicia with ease, speed and reliability and which will give consistently good results.

In the earlier days of the art, attention was mainly directed to transfer materials which required the application of water to release the indicia. Such transfer materials were usually difficult to make, complicated in construction, and difiicult to store without deterioration. Moreover the necessity for using a liquid to effect the transfer gave difficulties in their application and in some cases rendered them useless for desired purposes.

In more recent years attention has been directed to the production of transfer materials from which the indicia could be transferred without the use of any treatment liquid, so called dry transfer materials. In some such materials heat is required in order to release the indicia from the carrier support, e.g. for the purpose of softening a waxy release layer. It has also been proposed, more recently, to apply to the surface of the indicia a pressure sensitive adhesive so that the indicia, being very firmly adherent to the pressure sensitive adhesive layer would release from the carrier support and adhere, with the said adhesive, to another support.

In general, with this latter type of product it has been necessary to provide a protective sheet over the pressure sensitive adhesive, which sheet was peeled away as a step immediately prior to the transfer of the indicia to another support. The protective sheet was necessary since otherwise the transfer material was impossible to handle as a commercial article -owing to its readiness to stick to anything placed in contact with it, i.e. sheets of such material could not be stacked for packing purposes. Moreover the necessity for removing the protective sheet immediately before using the transfer material led itself to two major difficulties. On the one hand the actual operation of removing the protective sheet not infrequently pulled away from the carrier sheet the pressure sensitive adhesive and part, or the whole, of the indicia and, on the other hand, even if the protective sheet was peeled off without damage to the other layers it left a material which because of its readiness to stick to anything on the lightest contact cou-ld not easily be manipulated to position it for accurate register of the indicia to the surface where it was required.

If it is provided that the pressure sensitive adhesive is present only in register with the elements of the indicia this difiiculty is overcome but in practice it is extremely 3,212,913 Patented Oct. 1,9, 1965 ice difficult to maintain exact register in successive printing operations and it usually arises that the indicia transfers with an edging of imperfectly registered adhesive. This edge is unsightly and, being tacky, tends to pick up dirt after transfer so that the transferred indicia may become spoilt in a very short time by the accretion of dirty marks round the elements of the indicia.

Absolute accuracy of register is difficult to achieve so that such methods have usually only been employed where the indicia are -of very simple form, e.g. straightforward geometrical designs.

Furthermore, dry transfer materials of the type just discussed have usually used a paper carrier support, sometimes a laminar product of a fair degree of complication, which has had a very limited transparency or translucency (if indeed it was not opaque) so that accurate positioning of the transfer material, when the transfer is being effected, is the more difficult. Moreover, such carrier sheets based on paper have often suffered from the disadvantage of dimensional variation with atmospheric conditions, and have often had a serious tendency to curl.

As a result of very considerable research and experiment it has been found possible to overcome the aforesaid difficulties and it is a primary object of the present invention to provide a form `of transfer material such is stable on storage, very simple indeed to use and which gives consistently good transfers.

According to the present invention there is provided a transfer material comprising a light transmitting extensible base sheet printed with indicia on one face and said indicia super-coated with an adhesive, the adhesive being of a character which will not adhere to another surface under light finger pressure but which will adhere to another surface when a substantial pressure is applied to the reverse side of the base sheet, whereby when the base sheet is subsequently lifted away the indicia remains, stuck by the adhesive, on said other surface.

More specifically according to the present invention there is provided a transfer material comprising a carrier sheet consisting -of a sheet of transparent or translucent lm of high dimensional stability under normally varying conditions of temperature and humidity but which is readily capable of stretching on application of tension thereto, indicia in printing ink carried by said carrier sheet, said printing ink being based essentially on a polymeric material and containing a plasticiser therefore, and a thin layer of -a pressure sensitive adhesive extending over the whole of the printed area of the carrier sheet on the printed side, the adhesion between the said indicia and the carrier sheet being reducible by local stretching of the carrier sheet in the region thereof, and the pressure sensitive adhesive being substantially non-bonding at pressures less than 50 lbs. per square inch.

It is to be noted that if, in a transfer material according to the presen-t invention the pressure sensitive ad-V hesive layer is omitted, then the application of local pressure to the reverse side of the carrier causes the printed indicia to separate integrally from the carrier sheet. This result is achieved by selecting a carrier sheet which is readily capable of stretching on application -of tension thereto and formulating the ink lso that the indicia will so separate on the local appli-cation of stretching tension to the carrier sheet, i.e. the effect of such stretching must be to apply a force to the indicia which is greater than the adhesive force between the indicia and the support.

There is thus la 'fundamental difference between the transfer material-s of the present invention and those of the prior 4art referred to above. The prior art materials have relied essentially on the use of a surface adhesive of greater Iadhesive power to the transfer surface and to the indicia than the adhesive power of the indicia to the carrier, i.e. the surface adhesive has acted to pull the indicia away from the support and hold it to the transfer surface. 4In the material-s of the present invention, in contra-st, the separation of the indicia from the support `derives essentially from a manipulation of the support and not by the pulling power of some applied adhesive, and the thus-loosened indicia are simply stu-ck by the high pressure adhesive t-o the transfer surface. IIn consequence it is made possible to employ an adhesive which is not ya bonding adhesive at low pressures.

Transfer materials according to the present invention are easy to handle 4since the pressure sensitive adhesive will not bond to .anything with which it cornes into contact unless a substantial pressure is applied. It is accordingly not necessary to provide a protective sheet semipermanently stuck to the adhesive surface. It is desirable in practice to interleave the transfer materials with, Ifor example, silicone-treated interleaving paper but this paper does not stick tightly to the Iadhesive layer and will usually separate under its own weight.

Furthermore, the transparency or translucency of the support -sheet enables the transfer material to be accurately positioned rfor use since the indicia can be seen through the back of the sheet. The whole product is stable under normal storage conditions and when required for use it is only necessary to apply it to the surface on t-o which the transfer is to be made, and -apply a pressure in excess of 50 lbs. per square inch to the back of the carrier. The indicia then release from the support sheet and become adherent to the said surface. In practice it is usually necessary only to apply pressure to the back of the sheet with a hard object in the area of the indicia, covering at least part of the perimeter of the elements of the indicia, using a sufficient pressure to effect the release and simultaneous bonding.

The adhesive is applied as a thin layer over the whole surface of the printed side of the carrier and it is found that, provided it has a lower tensile strength than that of the printing ink and good adhesion to the non-printed areas of the carrier, it Will shea-r round the elements of the printed indicia so that only the adhesive coated n the printed indicia will transfer.

Whilst various types lof translucent or transparent film material-s are suitable 'for use as carrier sheet-s in the present invention, it is found that particularly good results are obtained by the use of self-supporting films formed of polyalkylene derivatives, e.g. polyethylene, polypropylene and copolymers containing at least 90% of either of these polyalkylenes.

The preferred material for use is polyethylene ilm made of polyethylene of density 0.96 g./.m.'l., melt index 0.2 (method of BS 1972); softening point 122 C. for 30 deflection (BS 1493); tensile strength 4200 p.s.i. (BS 2571); elongation at break 100-500%; Young Modulus 2.0 105 p.s.i.; and Water absorption less than .01% vafter 30 days immersion. The above polymer has a different molecular structure to conventional polyethylene, having linear and more regular polymer chains with very little side chain branching, which impart a high degree of crystal'linity of about 93%. This structure provides the physical and chemical properties required for use in the present invention namely, stiffness, strength and elongation in very thin lm form, and resistance to temperature, water and solvents.

The lm suport may be, for example of thickness 0.001 to 0.008 inch and may have a glossy, matt or -semimatt surface and the transferred indicia will have a Icorresponding surface. A matt surface to the transferred indicia is sometimes of value where the transferred image is to be used `for photographic reproduction.

The indicia are applied to the carrier support sheet by a printing operation. The formulation of the ink is yof importance in order that it should meet the requirements set lforth above, i.e. that it should adhere sufficiently` to the -support and yet be freed from the support by localised stretching of the support. The ink consists essentially of a high polymer and a plasticiser therefor. Generally it is found desirable to select a high polymer which, if used alone, would release spontaneously tfrom the support and then to add to it lsuflicient of a plasticizer as to achieve the desired level -of adhesion to the support.

Thus, for example, a clear ink medium may be prepared from a high polymer of cellulose nitrate of extra low, low or medium viscosity type, being an ester soluble grade, of nitrogen content of ILS-12.3%, or a spirit soluble grade of nitrogen content 10.5-11.2%. The cellulose nitrate may be employed damped in butanol, or the like, with 65 to 70% polymer solids. The cellulose nitrate is dissolved in a solvent suitable in volatility for the particular printing process, and which does not dissolve, curl or distort the carrier sheet. Aliphatic or aromatic hydrocarbon solvents are undesirable, but esters, ether-esters, ketones, alcohols, ether-alcohols, ketonealcohols are suitable on the polyethylene carrier support referred to above. A particularly suitable solvent for screen process printing, having low odour and a low evaporation rate, is ethylene glycol monoisopropylether acetate. A high polymer solution as thus formulated provides the necessary tensile strength of the dry ink iilm, but used without the inclusion of placticiser would give indicia which would spontaneously release from the carrier sheet.

A plasticiser must be added to the lhigh polymer solution to impart exibility according to the known principles of lacquer formulation .and also to control the release to precisely the required value by a most careful control of concentration. Two types of plasticiser may be used; one type is the so called solvent plasticiser which may provide part of the plasticiser content and is usually a non-polymeric material of low volatility, usually an ester, which is compatible with the high polymer and has a softening or dissolving action on it. Examples are dioctyl phthalate, tributylcitrate, dimethylcyclohexyl adipate, trixylenylphospate. The second type of plasticiser is a non drying oil (i.e. non oxidising) modified polyester, compatible with the high polymer.

The following oils, alcohols and acids may be variously rrployed in the production of such polysters:

Castor oil Hydrogenated castor oil Coconut oil Alcohol:

Ethylene glycol Glycerol Pentaerythritol Trimethylopropane Acid:

Phthalic (or anhydride) Isophthalic Terephthalic Adipic Sebacic A particularly advantageous plasticisor is a polyglyceryl sebacate, of 72% castor oil content and having a viscosity x-y, Gardner-Holdt scale.

In general terms, using cellulose nitrate as the polymer there may be Used, for parts of cellulose nitrate, 20 to parts of plasticisor, e.g. 55 to 150 parts of a castor- 011 modled alkyd resin or hydrogenated castor-oil modiiied alkyd resin.

The PflfhlUlg iIlkS Sed may be clear or pigmented or dyed and it 1s found to be particularly advantageous to formulate them so that they may be applied by silk-screen prmtmg methods.

It' Wlu geperally be found suiiicient to so formulate the mk that 1t will adhere to the carrier sheet at pressures below 2 lbs. per square inch but will release from the carrier sheet at pressures of 50 lbs. per square in ch or more.

If desired the printed indicia, which may be a clear non-pigmented ink, may be overprinted with a normal type printing ink applied by any conventional method, e.g. by screen process, letterpress, olset litho, gravure, flexographic or brinzing processes, and this overprinting may constitute the means whereby colouration or opacity is imparted to the indicia.

In a preferred form of the invention there is, over the indicia, a layer of a pressuresensitive adhesive having a tack-controlling component that is believed to take the form of a surface shield. To this end there may be used a composition which comprises as a first component, an elastomer which is intrinsically tacky or which has admixed therewith a resin imparting tackiness thereto, and, as a second component, a substance which reduces the tack of the composition to a level not exceeding a peel bond value of and, preferentially, not exceeding 10 grams per linear inch at a pressure of 0.5 p.s.i., the composition exhibiting gradually greater peel bond values at higher pressures up to a maximum peel bond value under a pressure of 50 p.s.i., or more.

When such an adhesive composition is used as a layer on a flexible base, it is almost non-tacky so that when placed on the receptor surface it may be moved into an exact position without -diiculty and without damage to the adhesive sheet or to the receptor surface by premature adhesion. After such positioning, the application of light fixing pressure will lightly adhere the adhesive sheet to the receptor surface and a strong pressure will increase the strength of adhesion up to a maximum adhesion value above which higher fixing pressure has no further effect. This maximum adhesion value may be predetermined to be such as to permit the adhesive base sheet, or any printed or coated element on such sheet directly under the adhesive layer, to be subsequently removed from the receptor surface without damaging the receptor surface. For example, the adhesive base or element may be removed by pulling off with a piece of ordinary tacky adhesive tape. When using a paper or similarly fragile receptor surface, an adhesion of 100 grams per linear inch peel bond is a suitable maximum value to avoid paper tear or delamination when removing the adhesive base or element.

The fixing pressure required to cause maximum adhesion is essentially a high pressure, ranging from 50 p.s.i. to 500 p.s.i. or more, and yhigh pressures of 500 or 1,000 p.s.i. are readily achieved by making a series of strokes over the back of the adhesive sheet with a stylus or ballpoint.

As noted above, the adhesives preferred in this aspect of the present invention contain two main components, which, for convenience are referred to herein as Component 1 and Component 2. Component 1 is an elastomer which is intrinsically tacky or is rendered tacky by the usual tackifying resins and will, accordingly, adhere on contact. Component 2 is a substance which reduces tack and prevents the adhesive composition from adhering on light contact but is such lthat, on the application of a high fixing pressure of 50 p.s.i. to 500 p.s.i. or more, the composition will adhere to a predetermined maximum adhesion value and, at pressures below that required for maximum adhesion, Will adhere with proportionally lower adhesion values, until at a pressure of 1/2 p.s.i., an adhesion of l5 grams per linear inch peel bond, `or less, is exhibited.

Component 1 is preferably an organic polymer of K value at least l0 or molecular weight 10,000 or more, which is tacky and which yields films having a high elongation. Particular groups of polymers of value are the polyacrylic or polymethacrylic esters and acids, polyvinyl ethers, polyisoprene including natural rubber, polyvinyl esters, polychloroprene, polyisobutylene, polybutadiene, polybutene and copolymers of these with each other or with other polymerisable monomers.

Tackifying resins may be included to increase intrinsic tack such as hydrocarbon resins, terpene resins, and rosin,

6 hydrogenated rosin and their ester and polyesters. Preferred materials for Component l are a polyvinylalkyl ether in which the alkyl group contains 2 to 4 carbon atoms, or a polybutyl acrylate alone or copolymerised with methyl acrylate, or a mixture of these or either or both in admixture with polyisobutylene.

In preferred surface-shield adhesives Component 2 is a substance used at a concentration of 15%-50% by weight of the adhesive composition and is physically characterised as a substance which is deformable or flows under a high pressure of 50-500 p.s.i. and provides an adhesive composition with a durometer hardness of units or less (see ASTM 676-49T). Chemically, Component 2 may be selected from classes of organic compounds containing one or more hydrocarbon or hydrocarbon ether chains totalling at least l2 carbon atoms which are believed to provide the low molecular forces responsible for deformability under pressure. Preferably, such compounds have a molecular weight -of 800 or less.

T-o the touch, some of these compounds may appear waxlike, fatty, or greasy but they are not necessarily waxes and the adhesive composition is distinctly elastomericor rubbery and does not exhibit wax-like properties, such as low scratch resistance, transfer or offsetting under pressure of the type shown by carbon paper, or melting to a thin liquid when heated to a relatively low temperature. It is believed that the adhesive composition exists as two phases in which particles of tacky Component l are shielded by particles, or a surface film, of Component 2, until a pressure of 50-500 p.s.i. or more is applied, which causes Component 2 to flow or deform, and allow Component l to contact Vand adhere to the receptor surface. Therefore, the concentration of Component 2, its deformability, its particle size and distribution are factors which are controlled as required to select the pressure/ adhesion curve, the threshold pressure for adhesion and maximum adhesion value as may be required for any particular product of this invention.

Particular organic compounds which may be used as Component 2 are long chain hydrocarbons, carboxylic acids of long chain hydrocarbons, and their metallic salts, esters, polyesters, amide, nitrile and amine and quaternary ammonium derivatives, alcohol derivatives of long chain hydrocarbons, and polyglycol derivatives.

Especially valueable are the esters of polyhydric alcohols and fatty acids which may be prepared by direct esterification of tihe polyhydric alcohol by the free fatty acid at elevated temperature for some hours, with constant stirring. An alkaline or metallic soap catalyst may be used to accelerate the reaction. Usually, an excess of fatty acids is used over the stoichiometric ratio for the mono or diester; this excess acid may be left in the final product or may be neutralised with sodium bicarbonate to leave a proportion of metallic soap in the ester.

Suitable polyols and acids are:

Polyol:

Ethylene glycol Diethylene glycol Trimethylene glycol and a propylene glycol D-Sorbitol Pentaerythritol Fatty acid: Laurie Palmitic Stearic The mono esters of the glycols and the mono and diesters of 'the trihydric alcohols are particularly suitable since they are 4readily dispersible in cold or hot Water, using an anionic surface active agent. For example, diethylene glycol mono stearate and glyceryl monostearate are readily dispersible in water. Component 2 itself may be surface active which may assist absorption and shielding of Component 1 particles.

It is sometimes advantageous to include in Component 2 a small proportion of a polyglycol.

According to known pressure sensitive adhesive technology transparent llers, such as silica, in the form of line powders, may be incorporated in the adhesive composition to improve stability, coating or printing properties and to reduce costs. Such powders may be used in the adhesive as a third component but if used in high concentration they will reduce the tack of Componentll s-o that a highly tacky form of Component 11, ysuch as polyisobutylene of low molecular weight, must then be used. The concentration of Component 2 may be also reduced to compensate for the tack reducing properties of the powder.

In the production of the adhesives useful in practicing the invention it is preferred to form a water-based liquid composition by intermixing a solution, dispersion or emulsion in water of Component 1 with a solution, dispersion or emulsion in water of Component 2. Dispe-rsing or emulsifying `agents may be added to assist in the production of dispersions or emulsions, e.g. anionic, cationic, ampholytic or non-ionic surface active agents. Alternatively, an organic solvent-based liquid composition may be produced by intermixing an organic solvent solution of Component 1 with an organic solution or dispersion of Component 2.

The following examples, in which the parts and percentages are by weight, illustrate adhesives used in the invention.

Example 1 An aqueous emulsion is made up of the following components.

Parts Water 45.27 Non-ionic surface active agent 1.2 Anionic surface active agent 0.3 Hydroxyethyl cellulose I0.55 Potassium persulphate 0.33 -Borax 0.35 Monomer or monomers (see below) 52.0

Suitable monomers are, for example, vinyl caprate, butyl acrylate, ethyl hexyl acrylate and vinyl butyl ether. 'Particularly valuable results are obtained by using butyl acrylate alone or with 20% methyl methacrylate.

All the components except the monomer are dissolved in the water and charged to a reactor vessel. A slow stream of nitrogen is passed over the liquid and 10% of the monomer (or mixture) is added with stirring. The temperature is then raised to 75 C. and the rest of the monomer added over 2-3 hours. This gives a smooth milky emulsion, viscosity 50-2000 c.p.s. with particle size of about l1 micron with a molecular weight of 10,000- 200,00 depending on the monomer and reaction conditions. If the emulsion is coated on a exible polyvinyl chloride iilm at a dry thickness of 0.002 inch, and dried by evaporation, a clearly tacky film is obtained having elastomeric properties and high elongation and will adhere to a receptor surface such as glass under light contact and will adhere with maximum adhesive when a pressure of 1/2 p.s.i. is applied to give a peel bond of 300- grams per inch.

An aqueous viscous dispersion of a fatty acid ester of a polyhydric alcohol, such as glycerol monostearate, is formed from 2 parts of ester and l2 parts of water. To this is added 8 parts of the emulsion described above at 50% solid content, to give a concentration of 33% of the ester on the total solids content of the adhesive. This liquid adhesive is a thin paste which may be printed by the screen process on to a polyethylene exible base 0.002 inch thick, and after drying gives a dry adhesive layer of 0.0003 inch thickness. This adhesive has a rubbery feel and is almost nonsticky to the touch and will not adhere to paper or glass under its own weight. At a pressure of 500 p.s.i., the adhesive will adhere rmly with a peel bond of 75 gramsper inch and may be subsequently peeled away without da-mage to the paper surface.

Example 2 Polyisobutylene or polyvinylibutylether with K values of 10 to 65 are tacky materials and are dissolved in aliphatic petroleum, boiling range fll0 C.l20 C., to provide a solution of up to 50% solids. A 30% dispersion of microcrystalline hydrocarbon wax l75/ 180 F. (ASTM Test) with penetrometer hardness of 1.5 mm. is prepared by dissolving the wax in hot aliphatic petroleum of similar boiling range. parts of wax dispersion are added hot to 50 parts of the adhesive solution to provide, after drying by evaporation, a very low tack adhesive.

In this specification peel bonds are determined under controlled conditions in which a l inch wide strip of smooth, calendered, uncoated printing paper, caliper 0.0015 inch, previously conditioned at 20 C. and 55% RH. is placed on the adhesive surface at 20 C. and a uniform pressure of 1/2 p.s.i. is applied for 3 seconds, for example, using a flat weight cushioned 'by 1A; inch foam rubber. The peel bond is then immediately determined by peeling off the paper strip at right angles to the adhesive surface at a steady rate of l inch per 5 seconds, the average force required being the peel fbond.

The adhesive may be used over an indicia-printed base made according to the following example:

A clear ink which has excellent screen printing properties is formulated as follows:

Parts .by weight 33% solids cellulose nitrate low viscosity nitrogen PLS-12.3% in ethyleneglycol mono isopropyl ether acetate 12500 72% castor oil glyceryl sebacate 2545 Dimethylcyclohexyl adipate 255 The polymer to total plasticizer ratio (which controls the release properties) is 100:67 in this ink.

A modification of this ink to include pigment is achieved by the addition of 6000 parts of rutile titanium dioxide and adjustment of the polymer to total plasticizer ratio to 100:81.

Such clear or pigmented ink medium is printed through a stainless steel or nylon mesh screen, the design being formed by a hand cut stencil for simple designs and a photostencil for complex designs, to provide a dry ink lrn thickness of 0.0005i0-0002 inch, on a polyethylene film (polyethylene density 0.96 referred to above).

The resulting transfer material may be used in the following manner:

The transfer material is placed, adhesive side down, onto the surface which is to receive the indicia, such as a sheet of drawing paper or lm. The indicia is registered with the surface and then pressure is applied using a standard ball-point pen having a .040 inch diameter ball, using a light writing load of 2 ozs. This constitutes an average pressure of 1600 p.s.i. since the pressure band is of .010 inch width, and causes a noticeable stretch in the carrier sheet which exceed the yield point of the film and can be seen and felt when the pressure is released. The pressure is applied as a series of strokes over at least part of the perimeter of each ink area, when uni-directional lifting away of the carrier lm is desirable. If pressure is applied over the whole of the perimeter of ink area the carrier film may be lifted away in any direction.

In practice a load of l to 4 ozs. is adequate, the lightest load being adequate when the nal surface is very soft and permits a large stretching of the carrier sheet and the higher loads when the nal support is hard, eg. glass.

The presently preferred form of dry transfer of the present invention, and its method of use, are shown in the accompanying drawing in which:

FIGURE l shows a diagrammatic section of the dry transfer material;

FIGURE 2 shows at left pictorially and at right in section the method and mechanism of transfer;

FIGURE 3 shows at left pictorially the result of the transfer operation and at right the residual elements of the transfer material in their new location.

Referring to these drawings, in FIGURE 1 there is shown the carrier lm 1 carrying indicia 2 (one such is shown) and adhesive 3. It will be noted that the adhesive extends beyond the margins of the indicia to overlap onto the carrier lm 1.

To effect the transfer, the dry transfer material is laid down with the surface of adhesive layer 3 in contact with a receiving sheet 4. Pressure is applied to the area of the carrier lm 1 behind the indicia 2 by means of a ball point pen 5. The effect is to stretch the lm 1 as shown and thus release the indicia 2 from the lm 1. Air thus enters between the indica 2 and the lm 1.

The dry transfer material is then lifted away as shown in FIGURE 3. The area of adhesive 3 which overlapped onto the lm 1 remains in position on the carrier lm 1 due to shearing of the adhesive around the edges of the indicia. The indica 2 however is adherent to the receiving sheet 4 by means of that part of the adhesive 3 which lay over the indicia 2.

What is claimed is:

1. As a new article of manufacture a dry transfer sheet which comprises a carrier sheet, an image of film-forming printing ink printed on a front face of the said carrier sheet and having a mechanically breakable bond thereto, and a low-tack pressure sensitive adhesive applied over the image overlapping onto the said carrier sheet, such that the image may be caused bodily to adhere, by means of said adhesive, to a receiving surface, by pressure applied to the rear surface of the carrier sheet in the region of the image, the cohesive strength of the adhesive, and its adhesive bond to the carrier sheet in the overlap areas, being greater than the adhesive bond established between the adhesive and the receiving surface on application of image-transferring pressure in the area of the image, the said cohesive strength and adhesive bonds being measured in a direction normal to the carrier sheet, the adhesive having such limited strength relative tothe strength of the image and the adhesion thereof by said adhesive to the receiving surface as to part around the outline of the image when the carrier sheet is pulled from the receiving surface after image-transferring adhesion to the receiving surface is produced by applied pressure both in the area of the image and in the overlap areas.

2. As a new article of manufacture a dry transfer sheet which comprises a light transmitting carrier sheet, a plurality of separate indicia of film-forming ink printed on a front face of the said carrier sheet and having a mechanically breakable bond thereto, and a low-tack pressure sensitive adhesive applied over the said indicia and overlapping onto the said carrier sheet, said adhesive having a Ilow tack at pressures of substantially less than about 50 pounds per-square-inch and a substantial tack at pressures above about 50 pounds per-square-inch, such that selected individual indicia may be caused bodily to adhere, by means of said adhesive, to a receiving surface, by pressure of at least 50 pounds per-square-inch applied to the rear surface of the carrier sheet in the region of the selected indicia, the cohesive strength of the adhesive, and its adhesive bond to the carrier sheet in the overlap areas, being greater than the adhesive bond established between the adhesive and the receiving surface on application of at least 50 pounds per-square-inch in the areas of the indicia, the said cohesive strength and adhesive bonds being measured in a direction normal to the carrier sheet, and the adhesive having such limited strength in relation to the strength of the indicia and of the adhesion thereof by the adhesive to the receiving surface as to part around the outlines of transferred indicia when the carrier sheet is pulled from the receiving surface after the adhesive is adhered thereto both in the areas of the indicia and in the overlap areas.

3. As a new article of manufacture a dry transfer sheet which comprises a light transmitting carrier film of high dimensional stability under normally varying conditions of temperature and humidity but which is stretchable on application thereto of a localized stress, a plurality of separate indicia of film-forming ink on a front face of the said carrier film and having a bond thereto that is mechanically breakable by local stretching of the carrier iilm in the region of the indicia, and a low-tack pressure sensitive adhesive applied over the said indicia and overlapping onto the said carrier film, such that selected individual indicia may be caused bodily to adhere, by means of said adhesive, to a receving surface, by pressure applied to the rear surface of the carrier film in the region of the selected indicia sufficient to stretch the carrier film locally and thereby break the bond between the carrier lm and the said indicia, the cohesive strength of the adhesive, and its adhesive bond to the carrier lm in the overlap areas, being greater than the adhesive bond established between the adhesive and the receiving surface on application of said applied pressure, the said cohesive strength and adhesive bonds being measure-d in a direction normal to the carrier iilm, the strength of the indicia and of the adhesion thereof by the adhesive to the receiving surface due to application of said applied pressure being greater than the strength of the adhesive so that the adhesive ruptures around the outlines of transferred indicia when the carrier film is pulled from the receiving surface after the adhesive is adhered thereto both in areas of the indicia and in the overlap areas.

4. As a new article of manufacture a dry transfer sheet which comprises a light transmitting carrier sheet, a plurality of separate indicia of film-forming printing ink on a front face of the said carrier sheet and having a mechanically breakable bond thereto, and a low-tack pressure sensitive adhesive of a high-tack adhesive component admixed with a tack-reducing low tensile strength deformable component applied over the said indicia and overlapping onto the said carrier sheet, such that selected individual indicia may be caused bodily to adhere, by means of said adhesive, to a receiving surface, and to transfer to said :surface by localized pressure applied to the rear surface of the carrier sheet in the region of the selected indicia, the cohesive strength of the adhesive, and its adhesive bonds to the carrier sheet in the overlap areas, being greater than the adhesive bond established between the adhesive .and the receiving surface on application of indicia-transferring pressure, the said cohesive strength and adhesive bonds being measured in a direction normal to the carrier sheet, and the strength of the indicia, and of the adhesion thereof by said adhesive to the receiving surface resulting from application of indicia-transferring pressure, being greater than the strength of the adhesive so that the adhesive is cause-d to part around the outlines of the transferred indicia when the carrier sheet is pulled from the receiving surface after the adhesive has been adhered thereto both in the areas of the indicia and in the overlap areas.

5. As a new article of manufacture a dry transfer sheet which comprises a light transmitting carrier sheet, a plurality of separate indicia of film-forming ink printed on a front face of the said carrier sheet and having a mechanically breakable bond thereto, and a low-tack pressure sensitive adhesive applied over the said indicia and overlapping onto the said carrier sheet, the adhesive being a low tack admixture of a high-tack adhesive component selected from the class consisting of acrylic and methacrylic ester land acid polymers and copolymers, vinyl ether and ester polymers and copolymers, polyisobutylene and polybutene, and a tack reducing low tensile strength deformable component selected from the class consisting of saturated long chain hydrocarbons and acids and esters and amides thereof and polymer of any of same and long chain alcohols and polyglycols, such that selected individual in- -dicia may be caused bodily to adhere, by means of said adhesive, to a receiving surface, on application of indiciatransferring pressure to the rear surface of the carrier sheet in the region of the selected indicia, the cohesive strength of the adhesive, and its adhesive bond to the carrier sheet in the overlap areas, being greater than the adhesive bond established between the adhesive and the receiving surface on application of said pressure in the areas of the indicia, the said cohesive strength and adhesive bonds being measured in a direction normal to the carrier sheet, and the strength of the indicia, and of the adhesion thereof by said adhesive to the receiving surface resulting from application of said pressure thereto, being greater than the strength of the adhesive so that the adhesive is caused to part around the outlines of the transferred indicia when the carrier sheet is pulled from the receiving surface after the adhesive has been adhered thereto in both printed and unprinted areas.

6. As a new article of manufacture a dry transfer sheet which comprises a light transmitting carrier sheet, a plurality of separate indicia of printing ink printed on a front face of the said carrier sheet and having a mechanically breakable bond thereto, and a low-tack pressure sensitive adhesive applied over the said indicia and overlapping onto the said carrier sheet, such that selected individual indicia may be caused bodily to adhere, by means of said adhesive, to a receiving surface, by indiciatransferring pressure applied to the rear surface of the carrier sheet in the region of the selected indicia, the cohesive strength of the adhesive, and its adhesive bond to the carrier sheet in lche overlap areas, being greater than the adhesive bond established between the adhesive and the receiving surface on application of said pressure in the areas of the indicia, the said cohesive strength and adhesive bonds being measured in a direction normal to the carrier sheet, the printing ink being formed of a cellulose derivative and a plasticizer therefor and the adhesive being a low-tack admixture of a high-tack adhesive component selected from the class consisting of acrylic and methacrylic ester and acid polymers and copolymers, polyisobutylene and polybutene, and a tackreducing low tensile strength deformable component selected from the class consisting of saturated long chain hydrocarbons and acids and esters and amides thereof and polymers of any of same and long chain alcohols and polyglycols, and t-he adhesive having such limited strength in relation to the strength of the indicia and of the adhesion thereof by the adhesive to the receiving surface as to part around the outlines of transferred indicia when the carrier sheet is pulled from the receiving surface after the adhesive is adhered thereto in both the printed and limprinted areas.

7. As a new article of manufacture, a dry transfer sheet in accordance with claim 1, wherein said ink is formed of a film-forming polymer and a plasticizer therefor and wherein said adhesive is an admixture of a first aqueous emulsion formed of two parts of ethylene glycol land a fatty acid of l2 to 18 carbon atoms in 12 parts of water and 5 parts of a second emulsion made up of:

Parts Water 45.27 Non-ionic surface active agent 1.2 vAnionic surface active agent 0.3 Hydroxyethyl cellulose 0.55 Potassium persulphate 0.33 Borax 0.35 Copolymer of butyl acrylate (80%) and methyl methacrylate (20%) 52.0

applied as a wet coating of between 1.1 and 2.2 grams per square foot.

8. As a new article of manufacture a dry transfer sheet which comprises a light transmitting carrier sheet, a plurality of separate indicia in printing ink printed on a front face of the said carrier sheet and a low-tack pressure sensitive adhesive applied over the said indicia and overlapping onto the said carrier sheet, such that selected individual indicia may be caused bodily to adhere, by means of said adhesive, to a receiving surface, by pressure applied to the rear surface of the carrier sheet in the region of the selected indicia sufficient to break the bond between the carrier sheet and the said indicia, the cohesive strength of the adhesive, and its adhesive bond to the carrier sheet in the overlap areas, being greater than the adhesive bond established between the adhesive and the receiving surface on application of that pressure which is sufficient to establish adhesion of said adhesive to the receiving surface in the areas of the indicia, the said cohesive strength and adhesive bonds being measured in a direction normal to the carrier sheet, and the ad-hesive being so thin and of such limited strength as to tear around the outlines of transferred indicia when the carrier sheet is pulled from the receiving surface after the adhesive in both the printed and unprinted areas is adhered thereto by pressure applied as aforesaid.

9. As a new article of manufacture a dry transfer sheet which comprises a carrier sheet, an image of lmforming printing ink printed on a front face of the said carrier sheet and having a mechanically breakable bond thereto, and a low-tack pressure sensitive adhesive applied over the image overlapping onto the said carrier sheet, such that the image may be caused bodily to adlhere, by means of said adhesive, to a receiving surface, by pressure applied to the rear surface of the carrier sheet in the region of the image, the adhesive being an ad-mixture having as a first component a tacky elastomer and as a second component a tack-controlling component shielding the surface of said tacky elastomer, the c0- hesive strength of the adhesive, and its adhesive bond to the carrier sheet in the overlap areas, being greater than the adhesive bond established between the adhesive and the receiving surface on application of image-transferring pressure in the area of the image, the said cohesive strength and adhesive bonds being measured in a direction normal to the carrier sheet, the adhesive having such limited strength relative to the strength of the image and the adhesion thereof by said adhesive to the receiving surface as to part around the o-utline of the image when the carrier sheet is pulled from the receiving surface after image-transferring adhesion to the receiving surface is produced by applied pressure both in the area of the image and in the overlap areas.

10. As a new article of manufacture a dry transfer sheet which comprises a light transmitting carrier sheet, a plurality of separate indicia of film-forming ink printed on a front face of the said carrier sheet and having a mechanically breakable bond thereto, and a low-tack pressure sensitive adhesive applied over the said indicia and overlapping onto the said carrier sheet, said adhesive having a low tack at pressures of substantially less than about 50 pounds per-square-inch and a substantial tack at pressures above about 50 pounds per-square-inch, such that selected individual indicia may be caused bodily to adhere by means of said adhesive, to a receiving surface, by pressure of at least 50 pounds per-square-inch applied to the rear surface of the carrier sheet in the region of the selected indicia, the adhesive being an admixture having as a first component, a tacky elastomer and as a second component a tack-controlling component shielding the surface of said tacky elastomer, the cohesive strength of the adhesive, and its adhesive bond to the carrier sheet in the overlap areas, being greater than the adhesive bond established between the adhesive and the receiving surface on application of at least 50 pounds per-square-inch in the areas of the indicia, the said cohesive strength and adhesive bonds being measured in a direction normal to the carrier sheet, and the adhesive having such limited strength in relation to the strength of the indicia and of the adhesion thereof by the adhesive to the receiving surface as to part around the outlines of transferred indicia when the carrier sheet is pulled from the receiving surface after the adhesive is adhered thereto -both in the areas of the indicia and in the overlap areas.

References Cited by the Examiner UNITED STATES PATENTS 2/34 Kubin 156-230 8/41 Jenkins 106--26 2/51 Carson 26o-28.5

14 A Whittgren 156240 Smith 156-240 McGarry 117-162 Karlan et a1 171-406 Shepherd 161-406 MacKenzie 156-230 EARL M. BERGERT, Primary Examiner.

Claims

1. AS A NEW ARTICLE OF MANUFACTURE A DRY TRANSFER SHEET WHICH COMPRISES A CARRIER SHEET, AN IMAGE OF FILM-FORMING PRINTING INK PRINTED ON A FRONT FACE OF THE SAID CARRIER SHEET AND HAVING A MECHANICALLY BREAKABLE BOND THERETO, AND A LOW-TACK PRESSURE SENSTIVE ADHESIVE APPLIED OVER THE IMAGE OVERLAPPING ONTO THE SAID CARRIER SHEET, SUCH THAT THE IMAGE MAY BE CAUSED BODILY TO ADHERE, BY MEANS OF SAID ADHESIVE, TO A RECEIVING SURFACE, BY PRESSURE APPLIED TO THE REAR SURFACE OF THE CARRIER SHEET IN THE REGION OF THE IMAGE, THE COHESIVE STRENGTH OF THE ADHESIVE, AND ITS ADHESIVE BOND TO THE CARRIER SHEET IN THE OVERLAP AREAS, BEING GREATER THAN THE ADHESIVE BOND ESTABLISHED BETWEEN THE ADHESIVE AND THE RECEIVING SURFACE ON APPLICATION OF IMAGE-TRANSFERRING PRESSURE IN THE AREA OF THE IMAGE, THE SAID COHESIVE STRENGTH AND ADHESIVE BONDS BEING MEASURED IN A DIRECTION NORMAL TO THE CARRIER SHEET, THE ADHESIVE HAVING SUCH LIMITED STRENGTH RELATIVE TO THE STRENGTH OF THE IMAGE AND THE ADHESION THEREOF BY SAID ADHESIVE TO THE RECEIVING SURFACE AS TO PART AROUND THE OUTLINE OF THE IMAGE WHEN THE CARRIER SHEET IS PULLED FROM THE RECEIVING SURFACE AFTER IMAGE-TRANSFERRING ADHESION TO THE RECEIVING SURFACE IS PRODUCED BY APPLIED PRESSURE BOTH IN THE AREA OF THE IMAGE AND IN THE OVERLAP AREAS.