GB2136353A - Transfer Materials - Google Patents

Abstract

Transfer materials are made by using a master sheet which is used in conjunction with an ink/adhesive material. The latter may take the form of a sheet coated with a removable image-forming layer, e.g. a black pigmented layer having thereunder a likewise removable adhesive layer, or it may be a wet ink which is acceptable only in certain areas of the master sheet and which dries on the master sheet to give an adhesive surface. The master sheet has indicia-defining areas such that when it is brought into contact with e.g. a coated sheet and pressure applied, coloured and adhesive layers on the sheet transfer from the coated sheet to the master to give a shaped indicium. Alternatively the master may be contacted with wet ink, the ink transferring only as a shaped indicium. This shaped indicium has, in the latter case after drying, its adhesive side outwards and can subsequently be transferred from the master sheet to a desired receptor surface, e.g. a piece of artwork or an article, by rubbing down in conventional fashion. The master can then be re-used by re- applying ink/adhesive material.

Description

SPECIFICATION Transfer Materials This invention relates to dry transfer materials.

In recent years, dry transfer materials have gained wide acceptance as an easy and convenient method of producing, on desired substrates, legends, usually formed of letters, which iook as though they have been printed there. The principal way in which such products have been commercialized is in the form of dry transfer lettering sheets which have been widely manufactured and sold such as, e.g. Letraset Instant Lettering sheets, Mecanorma Letterpress sheets and Dymo Transplus sheets. Products of this nature are described in British Patent Specifications 959,670 and 954,459.

A disadvantage of such products is that the sheet tends to become prematurely unusable or, at least, impractical to use, because the supply of letters on the sheet is limited and the supply of some types of letter on the sheet runs out before the sheet has been fully used. It is impractical to keep very large numbers of sheets in the hope of finding the odd unused letter and generally it is inconvenient to use sheets to their fullest extent.

A further disadvantage of such sheets is that they provide letters only in one colour in which they have been printed, usually black or white, though certain popular typefaces are available in a small section of standard colours. It is uneconomic to print the small runs of such materials for normal use. Attempts have been made in the past to alleviate this particular disadvantage, and British Patent Specification No.

1,347,011 discloses one solution to the problem.

In one aspect that specification discloses a dry transfer material where the indicia such as letters are of transparent ink to which a layer of coloured adhesive is applied, so that on subsequent transfer the coloured adhesive and the transparent indicium transfer together, the former providing colour and the latter protection for the adhesive. This system is somewhat tricky to use and has the particular disadvantage that it is sometimes difficult to see whether an indicium has been used or not since the indicia are transparent.

An alternative approach to manufacturing coloured materials while preserving some of the convenience of dry transfer is to use a perforated foil as a stencil as described in British Patent Specification No. 1 ,222,297. The process there described has not found widespread application.

Some of the problems noted above could be overcome if the user could himself make his own transfer material without the necessity of printing equipment. Systems in which a user has effectively formed a hand-made transfer material are known. Thus British Patent Specification No.

232,239 discloses a system in which a carbon paper ink type of layer is transferred under the application of pressure to the rear surface of a writing sheet, by the pressure exerted when writing on that sheet. After removal of the carbon paper type of material from the back of the written-on sheet, a sheet of paper can be inserted under the written-on sheet and a duplicate image of the writing obtained by pressing the two sheets together. This does not provide a particularly flexible system and the nature of the transferred image depends entirely on the manuscript image made by the user. It is accordingly unsatisfactory as a means of making dry transfers, e.g. of lettering in a particular type style which, when transferred, looks as though it had been printed.

Similar difficulties arise in the case of operator made heat transfers for example as disclosed in European Specification No: 0010319.

We have now found that dry transfer materials of good quality may be simply produced by a user if he is provided with a master sheet which can be used as a template or pattern for specific images, e.g. the letters in a particular typeface, and material which, when used in conjunction with that master sheet, can form a dry ink indicium having remote from the master sheet an adhesive surface, which indicium can be removed from the master sheet by using it in customary fashion as a dry transfer. The invention has the substantial advantage that the master sheet can be re-used.

Thus, according to a first feature of the present invention there is provided a method of manufacturing a dry transfer material which comprises taking a master sheet of material consisting of a transparent or translucent foil having on one side thereof images defined by a difference in surface activity of the sheet, bringing an ink/adhesive material into contact with the imaged side of the master sheet which is selectively retainable on the image areas on the master sheet to leave inkjadhesive images on the master sheet, which images are removable from the master sheet to a desired receptor surface by placing the master sheet image down on the desired receptor surface and applying pressure in the image area over the side of the master sheet remote from the ink/adhesive image and pulling the master sheet away.

Within this general approach, two specific ways of proceeding may be identified: The first is to apply by suitable means a liquid ink material which will wet the image areas but not the areas between them. Application may be by means of a suitable applicator such as a felt tip pen, brush or the like or the sheet may be brought into contact with a suitable surface bearing a film of liquid ink, for example a hand held roller or some other surface carrying a film of wet ink. In all these cases the ink is retained on the master sheet only in the desired image areas.

The material may be so formulated that when it subsequently dries down its surface adjacent the master sheet is non-adhesive or substantially non-adhesive (albeit that the ink images continue to adhere to the master sheet) while its surface remote from the master sheet may have a low permanent adhesive tack. The amount of tack required is very low indeed, particularly if the images when dry can easily be detached from the master sheet Materials not normally thought of as adhesive may be usable. For example suspension or dispersion of pigment/dyestuff in a suitable carrier applied using a felt tip applicator may when dried down have adequate affinity for e.g. a paper surface to enable the method of the present invention to be carried out.Alternatively, and preferably, use may be made of coating and drying techniques such as disclosed in British Patent Specification 1577617 to give a surface remote from the master sheet itself which is adhesive, the surface of the indicium adjacent the master sheet being non-adhesive once the master sheet has been removed following transfer of the indicium to a desired receptor surface.

Alternatively, a doubie application may be effected, first of an imaging material such as a suspension of pigment or dyestuff which is selectively taken up in the image area followed by a suspension of adhesive which is likewise selectively taken up only in the image area.

Operating in this way, some simple coating apparatus is required e.g. a simple roller coater, roller applicator, ball applicator or brush but this is generally simple and inexpensive to produce and can be used quickly and easily by hand. There is no need to provide printing apparatus.

An alternative way of proceeding is to bring the master sheet into contact with a layer of ink adhesive material on a suitable carrier sheet followed by peeling the master sheet and carrier sheet apart to leave ink/adhesive images on the master sheet with their adhesive side outward.

The carrier sheet may thus bear two coatings, first a layer of adhesive and secondly a layer of ink. By suitable formulation of the ink layer and adhesive layer and by ensuring suitable imagewise distributed surface characteristics of the master sheet, it may be arranged that when two such sheets are brought together, pressure is applied to an image area, and the sheets then peeled apart, the two layers of ink and adhesive are picked up in the area of the desired image and can subsequently be transferred therefrom to provide the desired image on the desired final receptor.

Using the system of the invention, very considerable flexibility in dry transfer can be provided. Thus, a user may be provided with a set of master sheets having imagewise defining areas on them corresponding to different typeface alphabets and a second set of colouring sheets which may be used selectively and repeatedly to colour areas of the master sheet to form coloured letters as desired. The master sheet is, of course, re-usable. Alternatively (though less preferably) simple coating apparatus and a set of liquid ink/adhesive compositions can be provided.

Preferably the master sheet consists of a base sheet such as a transparent or translucent plastics film having on one side either a reversed image of an array of desirable indicia or the negative of such an array. Such an image may conveniently be produced by printing. Screen printing is a preferred method but flexographic, lithographic and letterpress printing can also be used. The image may have a thickness of 0.5 to 30,a, and constitute an array of positive indicia or the negative of such an array.A positive reversed image is used where the printing material has a greater affinity for the imaging material than the base sheet, and a negative reversed image when the printing material has a lesser affinity for the imaging material than the base sheet. in the latter case the areas are of material which will not pick up the imaging material from a carrier sheet or roller, and these may conveniently be formed by printing in a release material, most preferably in a silicone resin material. In either case, the image should of course, be firmly adhered to the base sheet and this may be ensured, when the master sheet is produced by printing, by printing in a solvent based ink which solvent attacks, e.g.

softens or swells, the surface of the base sheet used. In order to facilitate use of the master sheet the printed image may be tinted so that the indicia show up easily.

The present invention includes both the method noted above and apparatus for carrying it out. Specifically, the present invention comprises means for applying indicia to articles comprising a master sheet as described above and a plurality of colouring sheets, each of the latter consisting of a paper or plastics film base, optionally coated with a release coat, on top of which are coated first a layer of an adhesive and secondly a dyed or pigmented imaging layer, both the adhesive and the imaging layer being suitably shearable, so that they can be bodily removed from the base by the master sheet as indicated above.

The following Examples will serve to illustrate the invention: EXAMPLE 1 A first sheet material was made up as follows: an adhesive was made up by ball milling the following components in the following proportions by weight: Polyisobutylene solution (Oppanol B50 ex BASF, 20% by weight solution in aliphatic hydrocarbon solvent (Exsol D145/160)) 3.6 parts Polybutene (Hyvis 200 ex B.P.

Chemicals Ltd.) 5.5 parts Glyceryl ester of rosin (Stabelite Ester 10 ex Hercules Powder Co.) 1.5 parts Silica (Aerosil 300 ex Degussa) 2.55 parts Ethylene glycol monoethyl ether 0.7 parts Aliphatic hydrocarbon solvent (Exsol 145/1 60 ex Esso) 17.0 parts This adhesive composition was coated on to release paper (type 30/111 ex Jointine) using a wire wound bar (wire diameter 0.3 mm) and dried.

Using the same coating method and apparatus, the adhesive layer was overcoated with a black ink prepared by mixing the following ingredients in the following proportions by weight: Carbon black (Elftex 1 50 ex Cabot Carbon) 30.0 parts Polyamide resin (Versamide 758 ex Cray Valley Products) 2.0 parts Toluene 100.0 parts Isopropanol 20.0 parts and the sheet then dried.

A second sheet material was produced by screen printing on to polyethylene terephthalate foil (thickness 75 microns, Melinex Type 542 ex ICI Limited) a printed image from a printing composition consisting of the following ingredients in the following proportions by weight: Silicone resin (Q2 7046 ex Dow Corning) 20.0 parts Silicone resin crosslinking agent (Q2 7047 ex Dow Corning) 2.0 parts Adhesion promotion agent (Type 297 ex Dow Corning) 0.2 parts This composition was screen printed on to the polyethylene terephthalate foil to give a dry coating thickness of 15,u. The print was cured at 1000C for five minutes to give a sheet bearing on one face an array of indicia defined by apertures in the printed coating.The indicia were in the form of standard alphabet and numerals, punctuation marks, etc. but in contrast to the normal array including a plurality of many letter types as used for dry transfe lettering sheets, the array consisted simply of the 26 letters of the alphabet in upper and lower case plus some double letters and letters with accents.

To carry out the method of the invention, the second sheet material was laid with its coated face up and the printed first sheet material laid printed side down on top of it. Pressure was then applied to the exposed back of the printed sheet in the region of areas corresponding to the letters CAT and the printed sheet lifted away. Black letters C, A and T were lifted away with the first sheet on its underside, each black letter consisting of a black ink layer and an adhesive layer. These black letters could then be transferred sequentially to a desired receptor surface to apply the word "CAT" thereto. The printed sheet could be re-used many times and the black coated sheet continued to be used until no black areas of adequate size to enable an indicium to be taken therefrom remained.

EXAMPLE 2 The adhesive of Example 1 was coated on to release paper type 30/111, as Example 1, using a wire-wound bar (wire diameter 0.2 mm).

The following pigment formulation was milled on a Silverson mixer for half an hour: Pigment Monolite Scarlet (ex ICI) 25 g Surfactant-the disodium salt of dioctyl sulpho succinate solution in isopropanol/water solvent (Anonaid TH ex ABM Chemicals Ltd.) 1 5 g Water 60 g This formulation was then made into the imaging coating.

Pigment formulation 10 g Water 10g Acrylic adhesive emulsion (Witcogrip Y1 1 7 ex Witco) 1 g This was coated over the adhesive using the same wire-wound bar.

The following release coat formulation was mixed together.

Silicone resin (Dow Corning Q2 7046) 20 parts Silicone cross-linking agent (Dow Corning 02 7047) 2.0 parts Adhesion promoter (Dow Corning 297) 0.2 parts Ethyl cellulose solution (5% K5000 ex Hercules Powder Co. in toluene) 60.0 parts This formulation was screen printed on to 75 micron thick polyethylene terephthalate foil (542 Melinex) to give indicia-shaped areas of uncoated film surrounded by the silicone coating. The printed sheet was cured at 1000C for 1 5 minutes.

The sheet materials were used as described in Example 1.

EXAMPLE 3 A room temperature vulcanising silicon rubber (Dow Corning Silastic RTV 734) was diluted with 20% of its own weight of ethyl acetate and printed through a screen on to 100 FL polystyrene sheets (Polyflex ex Du Pont) to give, after curing, indicia images defined by unprinted polystyrene surrounded by the silicone rubber coating. These sheets could be used as master sheets with colouring sheets of a commercially available black imaging sheet (Instantex No. 20, ex Letraset) and in the same fashion as described in Example 1.

EXAMPLE 4 The release coat formulation of Example 2 was screen printed onto 75 micron thick polyethylene terephthalate foil (Type 542 Melinex) to give indicia shaped areas of uncoated film surrounded by the release coating. The printed sheet was cured at 1000C for 1 5 minutes.

The sheet was then placed on a table printed side up and selected characters it was desired to transfer were rubbed over using a felt tip marker containing water soluble ink (Staedtler Lumocolor 355). The water soluble ink was retained on the uncoated portions of the polyethylene terephthalate foil, but was not accepted by the release coating.

The so coloured indicia were then allowed to dry at ambient temperature for 5 minutes, and the sheet inverted and placed over a pad of white paper. The letter images could be sequentially transferred therefrom by rubbing over the back with a ballpoint pen whereupon the coloured letter images were transferred to the paper when the polyethylene terephthalate sheet was peeled away. This process was repeated several times to build up the desired legend. The polyethylene terephthalate sheet could then be reused by repeating the process.

Claims (12)

1. A method of manufacturing a dry transfer material which comprises taking a master sheet of material consisting of a transparent or translucent foil having on one side thereof images defined by a difference in surface activity of the sheet, bringing an ink/adhesive material into contact with the imaged side of the master sheet which is selectively retainable on the image areas on the master sheet to leave ink/adhesive images on the master sheet, which images are removable from the master sheet to a desired receptor surface by placing the master sheet image down on the desired receptor surface and applying pressure in the image area over the side of the master sheet remote from the ink/adhesive image and pulling the master sheet away.

2. A method according to claim 1 wherein there is brought into contact with the imaged side of the master sheet a layer of ink/adhesive material on a suitable carrier, and the master and carrier sheet are then peeled apart to leave the removable ink/adhesive images on the master sheet.

3. A method according to claim 2 wherein the layer of inkladhesive on a suitable carrier is constituted by a carrier paper or plastics film bearing thereon successively a layer of adhesive, and a dyed or pigmented non-adhesive imaging layer.

4. A method according to claim 2 wherein the layer of inkXadhesive on a carrier is constituted by a layer of wet ink on a carrier, which wet ink, when dried down onto the surface of the master sheet in the image areas, has an adhesive surface remote from the master sheet and a non-adhesive surface adjacent thereto.

5. A method according to claim 1 wherein the ink/adhesive material is a liquid ink material which will wet the image areas but not the nonimage areas, and wherein the ink/adhesive material is applied using an applicator.

6. A method according to claim 5 wherein the applicator used is a felt-tip applicator or a brush.

7. A method of forming a dry transfer material substantially as hereinbefore described with reference to any one of the foregoing specific examples.

8. Transfer materials for applying indicia to articles, comprising a master sheet consisting of a transparent or translucent foil having on one side thereof images defined by a difference in surface activity of the sheet, and a plurality of colouring sheets each consisting of a paper or plastics film base bearing, in order, a layer of adhesive and a dyed or pigmented imaging layer, both being shearable and removable from the base sheet by application of the master sheet thereto under pressure and subsequent removal thereof, the adhesive and imaging layer being subsequently removable from the master sheet in the image areas by placing the master sheet adhesive layer side down, on a desired receptor surface, applying pressure in the imaged areas of the master sheet and peeling the master sheet away to leave the adhesive and imaging layer imagewise sheared and attached to the surface of the receptor.

9. Transfer material according to claim 8 wherein the master sheet consists of a transparent or translucent plastics film bearing on one side a negative reversed image in a printing material.

10. Transfer material according to claim 9 wherein the plastics film is of polyethylene terephthalate or a polystyrene and the printing material includes a silicone resin.

11. Transfer material according to any one of claims 8 to 10 wherein the colouring sheets each consist of a paper or plastics film base having coated thereon successively a layer of an adhesive and a dyed or pigmented imaging layer.

12. Transfer material according to claim 11 wherein a release coat is provided intermediate the paper or plastics film base and the adhesive layer.

1 3. Transfer material according to claim 8 and substantially as hereinbefore described with reference to any one of the foregoing specific Examples.