US3510385A

US3510385A - Dry transfer assembly

Info

Publication number: US3510385A
Application number: US569673A
Authority: US
Inventors: Alan Lennox Lythgoe; Bernard John Knowles
Original assignee: Letraset International Ltd
Current assignee: Esselte Pendaflex Corp
Priority date: 1965-08-03
Filing date: 1966-08-02
Publication date: 1970-05-05
Anticipated expiration: 1987-05-05
Also published as: GB1124082A; DE1300455B; BE684905A; SE317902B; NL6610945A

Description

May 5, 1970 A. L. LYTHGOE E L 3,510,385.

DRY TRANSFER ASSEMBLY Filed Aug. 2, 1966 2 Sheets-Sheet 1 FIG I United States Patent O US. Cl. 161-33 Claims ABSTRACT OF THE DISCLOSURE Transfer materials are described which comprise a carrier sheet, a plurality of transferable layers applied to the carrier sheet including at least one layer containing indicia, the outermost transferable layer being an adhesive layer and the innermost of the transferable layers being soluble or dispersible in an aqueous medium which has no substantial dissolving or dispersing action on its adjacent layer. The transferable layers are formulated so that the application of an aqueous medium thereto after transfer to a receptor surface of the transferable layers causes a visible alteration in the appearance of the transferred layer.

This invention relates to transfer materials, by which term is meant an assembly comprising a carrier sheet, transferable material, e.g. pictures, designs, characters or other symbols (hereafter referred to generically as dicia) carried on said carrier sheet, and means for releasing the transferable material from the carrier sheet and securing it to a receptor surface. When so transferred it is referred to herein as the transferred material.

A wide variety of transfer materials are known, differing in construction both as to the materials used and as to the means employed to effect the transfer of the indicia.

A particularly useful form of transfer material is the so-called dry-transfer material relying on the use of a pressure-sensitive adhesive. Examples of products of this type are described in US. Pat. No. 2,558,803 and British patent specifications Nos. 906,934, 959,670 and 954,459. Basically these products comprise a carrier sheet, indicia carried on said carrier sheet and an adhesive applied over the indicia. The adhesive may be in register with the indicia or may overlap onto the carrier sheet in those areas which are not covered by the indicia. The adhesive is preferably a pressure-sensitive adhesive and is for preference a nontacky pressure-sensitive adhesive as described in British patent specifications Nos. 906,934 and 959,67 0. It may also be an adhesive activated by heat.

In all the foregoing products and other transfer systems which have been proposed the transferred material is intended to be stable in the sense that the appearance of the transferred material is not intended to be subsequently changed. It is an object of the present invention, in contrast, to provide a transfer material which leads to transferred material of which the net appearance may be changed by a simple subsequent treatment. This possibility is of particular importance in the production of transfer materials for use as toys or educational aids to children since it provides for the child the double activity of carrying out the transfer operation and thereafter, if desired, subsequently altering the appearance of the transferred material, e.g. to effect a colour change, either locally or unformly, or to reveal aspects of the transferred material not visible following the initial transfer operation.

According to the present invention there is provided a transfer material which comprises a carrier sheet, a plurality of transferable layers, including at least one layer comprising an indicium, applied on said carrier sheet, the

Patented May 5, 1970 ice outermost of said transferable layers being an adhesive layer and the innermost of said layers being soluble or dispersable in an aqueous medium which has substantially no dissolving or dispersing action on at least a layer adjacent thereto, the layers being so formulated that application of the said aqueous medium to the transferable layers when the same are transferred to a receptor surface and bonded thereto by the said adhesive layer, causes a visible alteration in their net appearance.

In the principal application of transfer material according to the invention, as toys or educational aids, it is important that the solvent should be of the simplest possible form, which is water, and accordingly in a specific and preferred form of transfer material as just set forth the innermost of the transferable layers is soluble or dispersable in water while at least the layer adjacent thereto is substantially unaffected by water.

A wide variety of forms of transfer material may be made within the scope of the present invention.

By way of example two general forms of construction and one more specific form are illustrated in the accompanying drawings in which:

FIG. 1 is a diagrammatic cross-sectional elevation of a transfer material according to the invention.

FIG. 2 is a diagrammatic cross-sectional elevation of an alternative transfer material according to the invention.

FIGS. 3, 3A, 4, 5 and 5A illustrate the successive stages of use of a specific transfer material of the general type of that shown in FIG. 2.

Referring to FIG. 1, the transfer material comprises a carrier sheet 1 having applied to it a water soluble or water dispersable layer 2 and a pressure sensitive adhesive layer 3 which is not water soluble or dispersable. The receptor surface is shown diagrammatically at 4.

Referring to FIG. 2, the transfer material comprises a carrier sheet 1 having applied to it a water soluble or water-dispersable layer 5 a layer 6 which is not water soluble or water dispersable and a pressure sensitive adhesive layer 3 which is not Water soluble or dispersable.

The use to which the transfer is put will depend on the detailed features of the layers and the following are some of the possibilities.

Referring to FIG. 1:

Layer 2 (Water soluble or water Layer 3 (Not water soluble or dispersable) dispersable) Coloured plain Differently coloured plain. Bearing coloured indicia Opaque mask.

Different indicia.

Referring to FIG. 2

Layer 3 (not water Layer 6 (not water soluble or water Layer 5 (water so1- soluble or water uble or water The term coloured is used herein to include not only spectral colours and combinations but also black and white. A colourless layer is accordingly a substantially transparent layer. A plain layer is one where the appearance over its area is uniform (as distinct from an indicium).

Where reference is made to a mask it is to be understood that this may mask all or only part of the underlying layer. 7

FIGS. 3, 3A, 4, and 5A illustrate the stages in the use of a product of the type of FIG. 2. wherein layer 5 has an indicium of localised area compared with that of layer 6.

FIG. 3 shows the assembly transparent onto the receptor sheet 4 and FIG. 3A shows the appearance of the product at this stage. The localised indicium of layer 5 is that part of the design which constitutes the tree and it masks that part of layer 6 which lies beneath it.

FIG. 4 diagrammatically illustrates the removal of layer 5 by brushing it with water. The product is shown in FIG. 5 and the appearance of the product is then as shown in FIG. 5A: a figure in layer 6, hidden by the localised indicium of layer 5, has been revealed by re,

moving layer 5 by the water-brushing treatment.

Thus for example, a transfer may consist of successive layers of ink printed onto a carrier sheet of polyethylene film. In order of printing, a layer of gelatin suitably coloured by a dye or a pigment is first applied and dried; this is overprinted with a layer of an ink based on a soluble polyamide resin ink again coloured but in this case with a different shade of dye or pigment and the layer is dried; this is followed by printing a layer of an ink based on nitrocellulose, which may or may not be coloured. When this is dry the Whole assembly is coated with a non-tacky, shearable, pressure-sensitive adhesive (compare British patent specification No. 959,670). The transfer material is used by applying the adhesive side in contact with the receptor surface and the back of the polyethylene sheet is rubbed over with a stylus to effect the I transfer in the manner described in British patent specification No. 959,670. The transferred assembly of layers of ink and adhesive is then present on the receptor in the reverse order to that in which they were applied during printing of the said layers. Once present in this form the outermost gelatin layer can be removed from the receptor surface, without affecting the remaining layers by treatment with water. If the receptor surfaces is an absorbent surface such as paper, then the dissolved layer material may be taken up in the surface of the paper, so that the paper is coloured with the ink removed; an underlying ink layer is then exposed and provided with a differently coloured surround.

The foregoing is purely illustrative and it will be appreciated that the assembly may consist of a greater number of layers if desired. The most usual system, however, will consist of one coloured ink layer and a coloured adhesive or possibly two coloured ink layers and an adhes1ve.

Transfer materials according to the invention, as already noted, comprise (a) a carrier sheet, (b) one or more superimposed ink layers and (c) an adhesive, and suitable materials for these layers will now be described.

(a) Carrier sheet The carrier sheet may have a transparent, translucent or opaque surface, which can be matt, glossy, polished, semi matt or semi gloss, embossed or ridged, coated or uncoated. The thickness of the carrier sheet is not critical and may vary widely depending, inter alia, on the method of transfer being employed. Where the transfer is effected by the application of stylus pressure, as in British patent specification No. 959,670 the thickness should be such that the carrier may be locally deformed under such pressure.

The carrier sheet may be in reels or individual sheet form. It may be of a substance which is itself a self supporting film or may be a coated sheet material. The carrier sheet or the surface of the carrier sheet may consist of a polymer or copolymer, e.g. a polymer or copolymer selected from polystyrene and polystyrene homologues and substituted polymers including high impact polystyrene, polystyrene with rubbery additives such as butadiene as co-monomer, polystyrene butadiene acrylonitrile copolymer, acrylic polymers such as polymethylmethacrylate and other alkyl methacrylates, acrylic polymers with other polymers or co-monomers such as butadiene and acrylonitrile, vinyl polymers including vinyl chlorides, esters, acetals and alcohols and copolymers and with other polymers and co-monomers, cellulose esters and ether, polycarbonates rubber hydrochloride, polyolefins such as polyethylene of normal and high den sity and polypropylene, polyesters, polyamides and gelatine. Other suitable carrier sheets are cellulose materials of all types including those of natural origin such as paper or cardboard. Regenerated celluloses, metal foils of all types, including those such as tin, zinc, steel, copper, silver, aluminium, gold, paper laminates of polymers and co-polymers, and paper coated with such materials as silicones, or aluminum or chromium complexes, may all be used.

(b) Indicia layers The dry indicia may consist of a single organic polymer, wax, resinous material or inorganic salt or combinations of the various types and may also contain plasticisers, dyes, pigments, stabilisers, fillers extractors and/or ancillary agents.

Substances of relatively easy solubility or dispersibility in aqueous media which can be used, singly or in compatible admixtures, are for example, gelatin, bone, fish, skin and parchment glues; carboxy methyl cellulose, hydroxy propyl methyl cellulose; hydroxy ethyl cellulose; polyvinyl alcohol, starch, casein, gum arabic, gum tragacanth and other natural gums, sodium alginate, resinous vegetable extracts such as carageen, mucilages, fatty alcohols, polyethylene glycols, polypropylene glycols,

zem.

The method of applying the printing ink is not relevant to the end product and although the silk screen process is preferred, letterpress, lithographic, gravure or flexographic systems could well be used.

(0) Adhesive The adhesive of the dry transfer system, which may be water or solvent based, may comprise essentially a tacky polymer with or without a tack modifying agent, the modifying agent being either in admixture with the tacky polymer or applied as a second coating or surface layer. Suitable polymers and tackifying materials are natural unvulcanised rubber, vulcanised rubber, synthetic rubber such as polyisobutylene, polychloroprene, polybutadiene, polyacrylonitrile and copolymers of these and with styrene and styrene homologues and acrylic monomers, polyvinyl alkyl ethers such as methyl, ethyl, and butyl ethers, acrylic and methacrylic polymers such as polybutylacrylate and copolymers with polybutylmethacrylate, rosin and rosin derivatives such as hydrogenated rosin, esters and alcohols, liquid polymeric styrenes and styrene homologues, polymerized terpenes such as ,B-pinene, ketone resins and low molecular weight polyisobutylene.

Waxes and waxy materials are also suitable as functionable adhesives either alone or combined with tacky polymers. Examples are parafiin, microcrystalline waxes, polyethylene waxes, montan, carnauba, fatty acids and their derivatives such as metal salts, esters, alcohols, amides, nitriles and amines, fatty acid mono or polyesters of polyols, e.g. polyethyleneglycols and polypropylene glycols, and fatty alcohol ethers of polyols, e.g. polyethyleneglycols, and polypropylene glycols.

The method of application of the adhesive is not critical and any of the normal processes such as printing, coating, dipping and spraying may be employed.

The adhesive may of course be heat sensitive, so that the adhesive bond becomes greater on the application of heat, or function in such a manner as to react on the surface of the carrier sheet thereby creating an adhesive Example 1 A carrier film of bi-axially orientated polystyrene is printed with indicia, by means of the screen process printing method, utilising a steel mesh with an ink having the following constituents:

Percent Gelatine 34.0 Water 65.0 Auramine yellow dye 1.0

and produced by heating and stirring these ingredients together.

An adhesive is employed which reacts with the surface of the polystyrene sheeting, thereby creating a non tacky film on the areas of plain polystyrene and a tacky film on the indicia surface only. The adhesive has the formula:

In this example the transferred material is comprised of two differently coloured layers. The ink layer which is yellow and the adhesive layer which is blue. On transferring the indicia and then treating the upper ink layer with water this dissolves to form a yellow background whilst the original indicia is still preserved in blue, thus giving a two colour transfer. The same product may be made in differing colours and also in the form where the transferred image is an outline embracing open areas which can be subsequently filled with colour by application of water.

Example 2 This example utilises a polystyrene butadiene carrier sheet and is a multiple soluble layer system. The first ink layer is water-soluble having the following constituents:

Parts Hydroxyl-propyl methyl cellulose Water 83 Wetting agent 1 Methyl violet dye 1 The ink is also made by dispersing the components under high speed stirring. Over this is applied the second ink layer of the following constituents:

Parts Microcrystalline wax with combined tacky polymers 39 White spirit 58 Waxoline induline dye 3 This ink is made by dispersing the components with heating and high speed stirring.

The third and final adhesive layer is composed thus:

Parts Polyethylene wax 11.25 Polyvinyl butyl ether 22.50 White spirit 22.50 Methyl iso-butyl carbinol 42.75 Yellow dye (optional) 1.00

6 The adhesive is manufactured by dispersing under reflux the first three items and the whole mass is allowed to cool with stirring whilst the methyl iso-butyl carbinol is added slowly together with the colouring agent.

After transference the first ink layer can be dispersed by the action of water, revealing the second ink layer.

Example 3 Carrier sheet: polyethylene film.

Ink layer: Percent (a) Steryl dimethyl benzyl montanate 25 Butanol 74 Dye 1 or (b) Hydroxy propyl methyl cellulose 5 Isopropanol 49 'Water 45 Dye 1 Adhesive layer as in Example 2 The ink layer in both (a) and (b) is freely soluble in water but of the two ink systems quoted (b) is to be preferred for its working properties.

Where in the foregoing description reference is made to coloured layer it is to be understood that these may be intrinsically coloured, e.g. by a dye or pigment, or may be potentially coloured by including a substance which only imparts colour to the layer when the transferred material is treated with an aqueous medium, e.g. fine particles of dye which themselves impart virtually no colour but of which the tinctorial effect is achieved by their dissolution in the aqueous medium.

We claim as our invention:

1. A dry transfer assembly comprising a carrier sheet, a plurality of transferable layers applied on said carrier sheet, theoutermost of said transferable layers being an adhesive layer and the innermost of said transferable layers being adjacent said carrier sheet and at least a portion of said innermost layer being non-transparent and being soluble or dispersible in an aqueous medium which has substantially no dissolving or dispersing action on at least one transferable layer adjacent thereto, at least one layer other than said adhesive layer comprising an indicium, said transferable layers being formulated so that said innermost layer is substantially completely transferred to a receptor surface and bonded thereto together with said other transferable layers to become the outermost layer on said receptor surface and so that said outermost layer on said receptor surface is capable, upon application of an aqueous medium thereto of visible alteration in the total appearance of said transferred layers as compared with the total appearance of said transferred layers prior to application of said aqueous medium, said transferable layers being transferred to said receptor by application of pressure to the back surface of said carrier sheet.

2. A transfer material according to claim 1 wherein the said innermost layer is soluble in water.

3. A transfer assembly according to claim 1 wherein said innermost layer adjacent said carrier is colored.

4. A transfer assembly according to claim 1 wherein said innermost layer adjacent said carrier contains an indicium.

5. A transfer assembly according to claim 1 wherein said innermost layer adjacent said carrier is plain colored and carries an indicium.

6. A transfer assembly according to claim 1 wherein said plurality of transferable layers consists of two layers, the innermost of said layers carrying said indicium and the said outermost adhesive layer comprising a shearable pressure sensitive adhesive.

7. A transfer assembly according to claim 6 wherein said pressure sensitive adhesive is plain colored.

8. A transfer assembly according to claim 1 wherein said plurality of transferable layers consists of three 7 8 layers, said innermost layer being plain colored and/or 2,046,924 7/1936 Pendergast 161167 X carrying an indicium, the intermediate layer not being 2,409,564 10/1946 Heinecke. dissolved or dispersed by water and carrying an indicium 2,578,150 12/ 1951 Rathke. and said outermost layer comprising a pressure sensitive 3,015,574 1/1962 Gobel 1173.1 adhesive. 5 3,276,933 10/ 1966 Brant 161406 X 3,344,012 9/1967 Striim 161-406 X 9. A transfer assembly according to claim 8 wherein said outermost layer is colorless.

10. A transfer assembly according to claim 8 wherein ROBERT F. BURNETT, Prlmary Examiner Said outermost layer is colored R. O. LINKER, IR., Assistant Examiner References Cited 10 US. Cl. X.R.

1 1-167, UNITED STATES PATENTS 6 406 1,797,998 3/1931 Sadtler 161-167 X