US3519456A - Transfer materials - Google Patents

Description

United States Patent Olfice 3,519,456 Patented July 7, 1970 3,519,456 TRANSFER MATERIALS Kenneth James Reed and Alan Lennox Lythgoe, London, England, assignors to Letraset Limited, London,

England, a British company No Drawing. Filed Feb. 2, 1965, Ser. No. 429,904 Claims priority, application Great Britain, Feb. 4, 1964,

4,749/64; July 1, 1964, 27,218/64 Int. Cl. B41m 3/12; B44c N US. Cl. 1173.1 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to transfer materials by which term is meant sheet materials which comprise a carrier sheet carrying, on a surface thereof, a layer, or one or more printed indicia (herein called the transferable material), which while adherent to the carrier sheet can be released therefrom and transferred to a desired receptor surface when required.

Transfer materials are known and commercially produced which comprise essentially a carrier sheet, transferable material on a surface thereof, and a low-tack pres. sure sensitive adhesive superimposed over the transferable material, the whole so constructed that when such transfer material is laid down with the adhesive in contact with a desired receptor surface, the transferable layer will not, under light pressure, such as ordinary finger pressure, e.g. less than 2 p.s.i. transfer to the receptor surface but will, nevertheless, transfer on application of substantial pressure, e.g. that applied by rubbing the back surface of the transfer material, in the region of the transferable material which is to be transferred, with a stylus or the like. Such materials are described in British patent specifications Nos. 906,9'34 and 959,670.

Such products have proved to be of very considerable value when the transferable material consists of a plurality of indicia, e.g. the letters of the alphabet, numbers, mathematical signs, codes and the like, which may be separately and bodily transferred to a desired receptor surface as required so that, for example, words may be built up on the receptor surface by the successive transference of letters from the transfer material. For this reason the present invention is described with particular reference to materials carrying such multiple, separately bodily transferable, indicia though it is to be understood that the invention is not limited to such materials. By bodily transfer is meant that the whole indicium transfers leaving no part of it on the carrier sheet.

As just noted, in the foregoing type of transfer material, adhesive is superimposed on the transferable material. Where the transferable material is made up of a plurality of indicia it is clear that there are two possibilities for the application of the adhesive. It can be applied in register with the printed indicia since it is not required for use in any areas other than those of the printed indicia. This, however, is very diffioult to accomplish in practice and failure to secure exact registration can result either in part of an indicium not being covered with adhesive (in which case it may not transfer properly) or in an overlap of adhesive onto the carrier sheet (in which case, if the overlapping adhesive transfers it will form a margin to the transferred indicium which may pick up dirt and thus give a generally dirty surround to the transferred indicia).

A method of overcoming this difiiculty is described in British patent specification No. 959,670 which is to use an interrelated carrier sheet, transferable material and adhesive of such a character that, when the transferable material is transferred the adhesive, which is applied so that it covers the indicia but overlaps onto the carrier sheet the adhesive shears at the margins of the transferred indicium and remains, in the overlapping areas, adherent to the carrier sheet. In this way the difficulties inherent in the technique of registration are avoided and at the same time the difficulties attendent on non-registration are overcome.

Nevertheless the products in question clearly involve in their manufacture two separate operations in laying down on the carrier sheet the required indicia and the required adhesive. It is an object of the present invention to provide a new form of transfer material and a new method of making a transfer material in which not only are the foregoing disadvantages overcome but further advantages are obtained.

According to the present invention there is provided a transfer material which comprises a carrier sheet and, superimposed on a face of said sheet a layer of one or more indicia in a transferable material which is an ink itself containing a pressure sensitive adhesive ingredient, the said transferable material having a surface of low tack and the adhesive properties of the transferable material being so balanced in relation to the surface of the carrier sheet and a receptor sheet that when the transfer material is laid down with the transferable material surface in'contact with a receptor sheet the layer or indicia of transferable material does not transfer bodily under light pressure, e.g. normal finger pressure, but does transfer under the application of substantial pressure applied to the back surface of the carrier sheet e.g. by rubbing with a stylus, in the region of the transferable material to be transferred, at a pressure above 50 p.s.i.

The balance of properties referred to may be obtained by various methods which will now be described. In all the methods the carrier sheet should be one having a surface from which the transferable material (adhesive ink) may be bodily removed by application of pressure or by localised stretching of the carrier sheet. Suitable carrier sheets are, for example, sheets consisting of glassine or vegetable parchment, or papers such as glassine, vegetable parchment, kraft, sulphate or the like coated or impregnated with a cured polymethyl siloxane, or a Werner type chromium complex such as the stearic acid or myristic acid complex, or alternatively a plastic film such as polyethylene, polytetrafiuoroethylene, polypropylene, cellulose acetate, cellulose acetate butyrate, cellulose nitrate, ethyl cellulose, polycarbonate, polystyrene-butadiene, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride or copolymers or polyesters such as polyethylene terephthalate or hexamethylene diamine adipate.

Of particular interest are papers such as glassine, or vegetable parchment, or kraft glassine, uncoated or coated on one or both sides or impregnated with, a polymethyl siloxane or Werner type chromium complex. The pre ferred carrier sheet is vegetable parchment treated with a coating of methylpolysiloxane of a non-migrating type.

It is preferred, though not essential that the carrier sheet should be transparent or translucent since this makes for ease in location of the transfer material in use. It is to be understood that the term carrier sheet is used herein to include a carrier tape.

According to one aspect of the present invention the transferable material comprises ink ingredients including a proportion of a wax. Suitable waxes are carnauba wax, microcrystalline wax, oxidised microcrystalline wax, polythene wax, candolilla, beeswax, hydrogenated castor oil, montan wax, paraffin wax, carboxylic acids, esters or amides or polymers of these and long chain alcohols and polyglycols.

Whilst transferable material which consists essentially of ink ingredients and wax may usefully be employed, as above noted, the inclusion of a wax in an ink composition generally tends to reduce the tensile strength of the composition. Accordingly, in using products so made it is important that the transfer pressure should be applied over the whole of the area of the material to be transferred; omission of any area may result in that area not being caused to adhere to the receptor surface. In certain forms of the product this is not a disadvantage, e.g. where the indicia consist of closely spaced small shading dots or lines and the material is used to transfer such dots or lines only over a precisely selected area. However, when the indicia are of greater size, eg letters or numerals, it is preferred that the indicia should transfer even though strokes of a stylus may be slightly spaced apart during the transfer operation, and not cover every part of the area of the indicium and to achieve this result it is desirable that the transferable material should have a higher tensile strength.

According, therefore, to a further form of the invention the transferable material is formed of an ink which includes a tacky pressure-sensitive adhesive component together with a waxy or other non-tacky deformable component, the proportion of the non-tacky component being sufiicient to reduce the tack of the final composition to a level at which it will not adhere to a receptor surface under slight or finger pressure, the said composition further including a proportion of a high tensile strength polymer.

The tacky component may, for example, be a tacky acrylic or methacrylic ester or acid polymer or copolymer, a vinyl ether or ester, terpene, cresylic, maleic, or phenolic resin, or natural or synthetic rubbers such as neoprene or isoprene or cyclised rubber, or chlorinated rubber or such materials containing non-volatile plasticisers such as saturated polyesters, or non drying alkyds, or mixtures thereof.

The non-tacky component may, for example, be a high melting point long chain hydrocarbon, or carboxylic acid ester or amide thereof, or polymers of any of these, or a long chain alcohol or a polyglycol, or a natural wax.

Preferred high tensile strength polymers for use in this form of the invention are polyvinyl butyral or ethyl cellulose. Other suitable materials are cellulose nitrate; cellulose acetate; cellulose acetobutyrate; ethyl cellulose, ethylhydroxyethyl cellulose; alkyds and alkyds modified or copolymerised with a drying oil, styrene, urethane, vinyl, silicone or acrylic resin; polyvinyl-halides, -esters-acetals and alcohols; polyurethanes; epoxy polymers; epoxy phenolic, epoxy-polyamide and catalysed epoxy resins and copolymers; urea-, melamine-, and benzoguanamino-formaldehyde polymers; chlorinated and isomerised rubber; polystyrene and polyvinyl toluene; polysiloxanes and silicone containing polymers; polyacrylates, polymethacrylates and thermosetting acrylic resins; gelatin; zein, casein, starch or modified starch.

In this form of the invention, therefore, the ink consists essentially of a tacky component and a non tacky component as aforesaid, a high tensile strength polymer, and a pigment. The ingredients may be applied as a solution, dispersion or emulsion in organic solvent medium or water, the solvent or water being dried out after application.

It is generally found preferable to apply the various forms of ink referred to above by screen printing though other methods may be employed, e.g. gravure printing.

The indicia may be of any kind, e.g. letters, numerals, symbols, line drawings or the like. Particularly useful products are those in which the ink is applied as a texture pattern extending substantially over the whole area of the carrier sheet, i.e. so that the whole transferable layer is of said texture pattern. Such texture patterns may be for example an array of dots, shading lines, parallel or crossed, or irregular paterns, to simulate grain, textile fibre mat or other texture appearances.

When such sheets are used it may be provided that the indicia will only transfer where the pressure is applied so that localised areas of the texture pattern may be transferred. I

Thus, by way of example an outline drawing of a figure wearing a skirt may be treated with a transfer material according to this invention which carries a pattern simulating textile finish by applying transfer pressure only within the confines of the skirt outline so as to transfer the textile pattern to the skirt portion only of the drawing. Since in this case the transfer is required to be closely limited to the area over which the pressure has been applied it is desirable to employ an ink of suitable level of cohensiveness (as referred to later herein) in order that the layer'should fracture at the margins of the pressed area.

In accordance with yet another feature of the invention there is provided a method for the production of a transfer material which comprises applying to a carrier sheet a layer, or indicia, in transferable material which has, or is enabled to develop, a tacky surface sufiicient to enable it to adhere to a receptor surface under substantial pressure while the face of the transferable material originally in contact with the carrier sheet is or becomes substantially non-tacky. It will be appreciated that the merit of this technique is that there is substantially no tendency for the transferred indicia to pick up dirt on their surface.

Any convenient pigment well known for use in printing inks may be used in the ink formulations of the present invention including pigments modified by coating the pigment particles with surface active agents to improve dispersability and increase covering power. It will be appreciated that changes in pigmentation whether utilising unmodified materials or materials modified as aforesaid will involve other formulation changes in order to provide inks possessing the desirable properties for the transferable material of this invention. Pigments of particular value are carbon blacks and titanium compounds whilst modified pigments of particular interest are those in which the pigment particles are coated with aluminum or zinc stearates of amides of stearic acid.

Transfer materials of particular value are obtained when employing inks formulated Within the range encompassed by the following formulations in conjunction with the carrier sheets of vegetable parchment having a silicone coating.

Less Cohesive More Cohesive By evaporation of the solvent the dried ink will contain the first four only of the specified ingredients in the indicated relative parts by weight. It will be appreciated that alternative pigmentation will necessitate other variations in composition of the foregoing formulations and such variations should be made in cognisance of the working behaviour of the ink and the ultimate properties desirable in the transferable indicia. The cohesiveness refers to the property of the ink film when present on the carrier film in its normal condition for use as a transfer material. This range of formulations are very suitable for use when 5 the carrier sheet is in the form of a tape as there arises no trouble due to oif-setting when the tape is rolled.

A composition of the more cohesive type referred to above, used to print a multiplicity of characters on silicone-coated vegetable parchment, was subjected to test to determine the pressure required at different temperatures to transfer to a paper receptor surface 95% of the characters. At the same time an assessment was made of the working properties by a subjective measurement of the ease of use of the material when transferring single indicia by means of stylus pressure. The results were as follows:

It will be noted that higher pressure is required at the high temperature due to a loss of tack on the surfaces where the wax is semi-molten and increased adhesion of the ink to the carrier paper. The system works most satisfactorily between 1030 -C., which covers almost any climatic variation.

The following examples will serve to illustrate the invention.

EXAMPLE 1 A carrier sheet consisting of paper having a silicone coating, is printed with indicia. in ink of the following formulation:

Polyvinyl butyral solution (216% solids) in butanol-- 30-65 parts preferably 31.5 parts Microcrystalline wax dispersion (40% in white spirit) 20-5 parts preferably 44.5 parts Polyvinylethyl ether dispersion 70% in benzene-20 parts preferably 19 parts Pigment, carbon black-4-8 parts preferably 5 .0 parts In the foregoing formulation, there may be used, instead of butanol any other alcohol, ether or ester which is a solvent for the polyvinyl butyral, such as ethylene glycol monoethyl ether or acetate, instead of white spirit any other aliphatic or aromatic solvent for the wax and instead of benzene any other solvent for the polyvinyl ethyl ether e.g. toluene.

EXAMPLE 2 A carrier sheet consisting of paper having a silicone coating is printed with ink of the following formulation:

1 Parts Microcrystalline wax dispersion (40%) in aliphatic and/ or aromatic solvents 35.0

Polyvinyl butyral 26% in butanol 29.0

Polyvinyl ethyl ether 70% in toluene 90 Titanium dioxide 17.5

Terpene resin 115 solution 50% in white spirit 9.5

EXAMPLE 3 A carrier sheet consisting of paper having a silicone coating is printed with indicia in ink of the following formulation:

Aqueous paraffin wax emulsion (50% )65-85 parts preferably 76.5 parts Aqueous polyvinyl ethyl ether dispersion (50%)- 5-15 parts preferably 9.0 parts Polyisobutylene rubber latex (60% in water)--3-15 parts preferably 4.5 parts 6 Aqueous carbon black dispersion (10%)l0-20 parts preferably 10.0 parts EXAMPLE 4 A carrier sheet consisting of paper having a Werner type complex coating is printed with indicia in ink of the following formulation:

Parts Aqueous paraffin wax emulsion (50%) 76 Aqueous polymethyl methacrylate (50%) 11 Aqueous dispersion of carbon black (10%) 6.3 Surface active agent (Manoxol OT, 50% solution 1.7 Polyisobutylene rubber latex (60% in water) 5.0

EXAMPLE 5 A carrier sheet consisting of paper having a Werner type complex coating is printed with indicia in ink of the following formulation:

Polyethylene wax dispersion (20% solids in white spirit)4l-6O parts preferably 54 parts Ethyl hydroxyethyl cellulose (25% solids in aromatic solvent)-1427 parts preferably 19 parts Polyvinyl ethyl ether dispersion (70% in toluene)- 15-20 parts preferably 19 parts Carbon black4-8 parts preferably 8 parts EXAMPLE 6 A carrier sheet consisting of paper having a Werner type complex coating is printed with indicia in ink of the following formulation:

Polyethylene wax dispersion (20% solids in white spirit)32F44 parts preferably 39.0 parts Rubber solution (20% solids in white spirit)l5-23 parts preferably 16.5 parts Terpene resin solution (50% solution in white spirit)l0-20 parts preferably 15.0 parts White spirit20'30 parts preferably 24. 0 parts Carbon black 4 8 parts preferably 5.5 parts EXAMPLE 7 A carrier sheet consisting of paper having a silicone coating is printed with ink of the following formulation:

Parts Microcrystalline wax dispersion (40%) in aliphatic and/or aromatic solvents 37.7 Polyvinyl butyral 26% in *butanol 31.3 Polyvinyl ethyl ether 70% in toluene 9.9 Titanium dioxide 21.1

EXAMPLE 8 A carrier sheet consisting of polyethylene film is printed with indicia in ink of the following formulation:

The following ingredients are mixed to form a disand the whole dispersed on a triple roll mill.

In the printed product the plasticiser (di-isobutylphthalate) exudes to the surface of the printed indicia, thus maintaining the surface slightly tacky.

EXAMPLE 9 A carrier sheet consisting of paper having a silicone coating is printed with indicia in ink of the following formulaton:

The following ingredients are mixed to form a dispersion with the aid of heat and stirring:

= Parts Vinyl resin (Vinylite VYHH supplied byBakelite 'Ltd.) 7.2 Di-isobutyl phthalate 27.8 Chlorinated paraffin wax 14.4

This dispersion is mixed with the following:

V Parts Polyvinyl butyral (25% solution in ethylene glycol monoethyl ether) 20.0 Pigment (carbon black) 7.6 Ethylene glycol monoethyl ether 8.0 Xylene 15.0

and the whole dispersed on a triple roll mill.

In the printed product the plasticiser (di-isobutylphthalate) exudes to the surface of the printed indicia, thus maintaining the surface slightly tacky.

' EXAMPLE 10 A carrier sheet consisting of polythene fihn is printed with indicia in ink of the following formulation, the ingredients being mixed and dispersed on a triple roll mill.

Parts Unsaturated polyester resin 50-60 Tolylene di-isocyanate (40% solution in butyl acetate) 28-35 Pigment (carbon black) 10-15 In connection with the foregoing examplary inks it is to be understood that the composition may be varied to provide other colours (by addition of other pigments or dyes) or may be unpigmented.

We claim as our invention:

1. A transfer material which comprises a carrier sheet having a release surface and, superimposed on a face of said sheet, indicia formed of a transferable cohesive ink composition comprising a mixture of about 11.5 to about 14.5 parts by weight of a polyvinyl butyl ether as a tacky pressure sensitive component, about 17.5 to about 18.5 parts by weight of a microcrystalline wax as a low tack deformable component, about 8 to about 8.5 parts by weight of a polyvinyl butyral as ahigh tensile strength polymer and about 4 to about 5 parts by weight of a pigment, said transferable cohesive ink composition having a surface of low tack and the adhesive properties of said transferable cohesive ink composition being such that when said transfer material is laid down with said transferable cohesive ink composition surface in contact with a receptor sheet, said indicia formed of said transferable cohesive ink composition does not transfer bodily'under a pressure less than 2 p.s.i. butdoes transfer bodily under the application of psi. pressure applied to't he back surface of said carrier sheet. a 2. A transfer material according to claim 1 wherein the pigment is selected from the class consisting of carbon black, titanium dioxide and pigment particles are coated with a material selected frornthe classconsisting 0f alu: minum stearate, zinc stearate and amides of stearic acid.

3. A transfer material according to claim 1 wherein the transferable material is a layer constituting a texture pattern extending substantially over the Whole area of the carrier sheet.

References Cited UNITED STATES PATENTS 3,031,327 4/1962 Newman 106-31 3,036,924 5/1962 Newman 106-14.5 3,368,989 2/1968 Wissinger et a1. 117-36.1 2,139,068 12/1938 Bourdon '117-3.4 2,263,196 11/1941 Stolle et' al. 282-'28 3,131,106 4/1964 MacKenzie 156-230 3,212,913 10/1965 MacKenzie 156-230 OTHER REFERENCES Butvar and Formvar, Shawinigan Resin Corp., p. 33 cited, pub. 1963.

ROBERT F. BURNETT, Primary Examiner R. J. ROCHE, Assistant Examiner US. Cl. X.R.