GB1604775A

GB1604775A - Dry transfer with laminated carrier sheet

Info

Publication number: GB1604775A
Application number: GB2482778A
Authority: GB
Original assignee: ET Marler Ltd
Current assignee: ET Marler Ltd
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-12-16

Description

(54) DRY TRANSFER WITH LAMINATED CARRIER SHEET (71) We, E.T. MARLER LIMITED, a British Company of, Deer Park Road, Wimbledon, London, SWl9 3UE, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to pressure sensitive adhesive transfers laminated to a backing sheet and to a method for manufacture of such transfers.

Pressure sensitive adhesive transfers comprise a carrier sheet with one or more dry ink designs printed or drawn on the surface of the carrier sheet and a layer of pressure sensitive adhesive layer covering designs so that on application of pressure to the back surface of the carrier sheet over the selected design while the adhesive is in contact with a receiving substrate the carrier sheet can be peeled away to leave the design transferred to and adhered to the substrate. The term "design" includes pictures, typographical characters such as alphabets of various lettering styles and sizes, numerals, symbols, textures, titles, logos and text matter all of which may be clear or single-coloured or multicoloured.Such transfers are also termed "dry" transfers because the release of the designs from the carrier sheet is carried out without application of a liquid to effect release of the design or to actiirate the adhesive.

The pressure sensitive adhesive may have low or high tack. A low tack adhesive is usually used when there are several separate designs on a single transfer sheet so that each design can be accurately positioned and selectively transferred. A high tack adhesive is usually used where the transferred design is required to permanently adhere to a receiving substrate and for this dry transfer a single design is usually provided on the carrier to avoid accidental transfer of an adjacent design if more than one design is carried on the carrier sheet.

During the manufacture of such transfers whether on sheet-fed or web-fed printing machines it is necessary to laminate a backing sheet to the pressure sensitive adhesive layer to prevent accidental sticking or transfer of the designs during storage and handling. To apply a transfer the backing sheet is removed and the adhesive is placed in contact with the receiving substrate and pressure is applied to the surface of the carrier sheet over the design to cause bonding of the adhesive to the substrate and the carrier sheet peeled away.

Transfer may be prepared using a releasable layer as described in our copending applications 06068/78 (;Serial No. 1,603,972) and the transferable design layer may consist of one or more photopolymerised ink layers as described in our copending application 30430/77 (Serial No. 1,580,076) Multilayer transfers may also be produced according to our copending application 15855/78 (Serial No. 1,604,274).

To prevent excessive adhesion of the backing sheet to the pressure sensitive adhesive which would cause unwanted transfer of the designs onto the backing sheet it is normal practice to coat or impregnate the backing sheet with a release material such as polymerisable silicone composition and to polymerise this on the sheet to give a strongly adhering and non-migratory silicone backing sheet. Other release materials may be used such as polytetrafluorethylene, polyethylene, waxes and stearato-chromium Werner complexes. The sili- cone release material may be mixed with polymers and waxes.

The paper sheet to which the release layer is applied may range from tissue paper to heavy weight paper and many types of paper may be used including sulphite and sulphate fibrous, greaseproof, vegetable parchment and glassine papers as well as coated and plastic laminated and extrusion coated papers. One or both sides of the sheet may be release coated.

Considerable difficulty and cost is experienced in applying the backing sheet to the adhesive surface of the transfer sheet to provide the laminated pressure sensitive transfer sheet.

The transfer sheet usually emerges at high speed from the adhesive drying apparatus and the backing paper must be applied in a precise position without creasing and without stressing the transfer otherwise premature release of the transfer onto the backing paper will occur. This successful lamination becomes extremely slow or even impractical when individual large sheets of transfers are produced and a fllimsy backing paper is used.

According to the present invention there is provided a method of producing a dry pressure sensitive adhesive transfer wherein one or more transferable designs are supported on a carrier sheet and wherein the transfer is laminated to a backing sheet having a release surface, said method comprising laminating the carrier sheet of the transfer, prior to applying the pressure sensitive adhesive, with a backing sheet having a release surface so that the release surface faces outwardly and applying the pressure sensitive adhesive to the design or designs on the carrier sheet, the carrier sheet and the backing sheet being separable after drying the adhesive.It will be appreciated that in accordance with the invention, after drying the adhesive, the sheets are stacked or re-reeled so that the exposed release surface of the backing sheet is automatically laminated to the adjacent adhesive surface and automatically forms the backing sheet for the dry transfer.

There are several methods of laminating the carrier sheet and backing sheet together namely edge spot-glue and gloss/gloss lamination, thermoplastic lamination and wet lamination.

Spot-glue and gloss/gloss lamination are preferably used in combination. Since this adequately resists all the delamination stresses in the transfer printing processes, these methods of lamination are preferably carried out by reel to reel lamination method and the laminated web is then sheeted if sheet-fed transfer printing is to be used. The design or designs may be printed onto the carrier before or after laminating the carrier sheet to the backing sheet.

The invention includes a laminated dry transfer which comprises a carrier sheet having one or more transferable designs on one surface, each design bearing a coating of a pressuresensitive adhesive and a backing sheet laminated to the other surface of the carrier sheet, the exposed surface of the backing sheet having a release surface.

Gloss/gloss lamination requires that the laminating surface of the backing sheet is glossy and this is readily achieved by using machine glazed, calendered, friction glazed, gloss coated, coated and calendered or cast-coated paper.

Machine glazed (MG) paper including tissue paper is particularly suitable and is low in cost.

Such lamination also requires that the nontransfer printed surface of the carrier sheet is also glossy and such carrier sheets are readily prepared by casting, extrusion or calendering and include for example polyester, polystyrene, polystyrene-butadiene, polyvinylchloride homopolymer and vinylchloride-vinylacetate copolymer, cellulose acetate, polyethylene and polypropylene. The carrier sheet may also consist of paper or coated or plastic laminated paper such as glassine paper, polythene extru- sion coated paper and other carrier sheets many of which are described in our copending application listed above.

The laminating surface of the backing sheet need not be release coated.

Two smooth flexible glossy sheet materials cling together with a small peel bond when dry laminated due to the partial exclusion of air and sometimes strongly assisted by electrostatic attraction.

This mechanical laminate must resist all the stresses of sheet-fed printing machines particularly the tack of the ink as the sheet leaves the plate and also the air jets and sheetlift suckers used on the sheet separation mechanism of automatic sheet feeders. To resist the latter stress the spot-glue sheet edge is arranged to be the trailing sheet edge presented to the feeder sheet separator mechanism.

The leading sheet edge is then held together by the grippers so that delamination is impossible.

Such laminated sheets have been found to feed reliably and at very high speeds on all printing machines. A further advantage of laminated carrier sheets is that when oxidation drying inks are used the paper sheet assists ink drying by retaining air between the sheets and also prevents ink set-off on the nonprinted surface of the carrier sheet.

Edge spot-glue is used rather than a continuous glue line so that when the sheets are subject to printing pressure air retained between the sheets can be squeezed out between the glue spots.

After applying and drying the pressure sensitive adhesive to the laminated carrier sheets of the present invention the sheets emerging from the drier are simply stacked.

The release coated surface of the backing sheet automatically falls in the adhesive layer of the sheet below as sheets are stacked and produces a precision aligned crease-free laminate. A similar result is achieved using web-fed printing by re-reeling after applying and drying the adhesive.

The stack of sheets is normally guillotined down to the final required sheet size and during this operation the spot glue edge is dimmed off. When thermoplastic lamination or wet lamination is used then this may also be trimmed off if localised on an edge but even with an overall lamination, the bond of the adhesive to the backing paper is higher than that of the laminate bond so that the correct pair of sheets are readily separated from the stack.

The invention is illustrated but is not restricted to the following Examples.

Example 1.

A web of clear transparent cellulose diacetate film of 80 imam thickness is prepared by casting onto a matt engraved drum so that a plastic film is obtained having a high gloss finish on one side and a matt finish on the other side.

A shearable release layer of our copending application 06068/78 (Serial No. 1,603,972) is coated onto the matt surface of this film by roller coating using a 10% dispersion of stearamide wax in aliphatic hydrocarbon which is dried by hot air jets.

The gloss surface of the plastic is laminated to the uncoated, machine glazed side of a backing paper consisting of machine glazed paper of 30 gsm to which a silicone release coating has been applied to the non-glazed side of the sheet by reverse roll coating using a liquid polymerisable silicone solution in organic solvent which has been dried by evaporation and heating to 1200C to further polymerise or cross-link the silicone and render it nonmigrating and insoluble.

Lamination is carried out in the nip of a pair of hard rubber rollers and spots of hot melt glue are applied to either the film or paper web by a spot-glue coating wheel prior to the nip. On cooling a good spot-glue bond is formed at 5 mm from the sheet edge with spots of about 2 mm spaced apart by 5 mm and the general adhesion of the gloss/gloss surfaces adequately resists delamination during printing.

Example 2.

A semi-gloss extruded polystyrenebutadiene copolymer film of 90 rm thickness is coated both sides by roller coating with the shearable release layer of our copending application 06068/78 (Serial No. 1,603,972) using a 20% colloidal dispersion of stearamide wax in aliphatic hydrocarbon. A web of silicone back ing paper is laminated to one side of the wet plastic film by web tension whereby the non silicone side of the backing paper is laminated to the plastic film. After drying using hot air jet at 700C a laminate is obtained having a low peel bond adhesion of about 10 g/cm which resists delamination forces during subsequent printing processes for the preparation of a dry transfer.

The accompanying drawings illustrate the production of laminated transfer sheets in accordance with the invention. Referring to the drawings:-- Fig. 1 is a magnified illustration of a carrier sheet (1) having a semi-matt surface (2) and a smooth gloss surface (3). The carrier sheet is laminated to a silicone backing sheet (4) having a smooth machine-glazed surface (5) and a fibrous surface (6) with a silicone coating (7). The two sheets are edge-glued with spots of adhesive (8) and the remainder of the smooth surfaces of the two sheets are in dose physical contact.

The exposed surface of the carrier sheet carries an offset litho printed dry ink design as halftone dots (9), a clear high film strength layer (10) applied by screenprinting, a white screenprinting layer (11) and an overlapping low-tack pressure sensitive adhesive layer (12).

Fig. 2 illustrates a stack of printed carrier sheets in which the silicone layer (7) is in contact with the pressure sensitive adhesive (12). This assembly is then guillotined to remove the edge-glued spots (8) after a single silicone sheet is placed on the top carrier sheet.

The stack of sheets are then readily separated at the interface (13) to produce separate carrier sheets each produced with a backing sheet.

WHAT WE CLAIM IS: 1. A method of producing a dry pressure sensitive adhesive transfer wherein one or more transferable deSigns are supported on a carrier sheet and wherein the transfer is laminated to a backing sheet having a release surface, said method comprising laminating the carrier sheet of the transfer, prior to applying the pressure-sensitive adhesive, with a backing sheet having a release surface so that the release surface faces outwardly and applying the pressure-sensitive adhesive to the design or designs on the carrier sheet, the carrier sheet and the backing sheet being separable after drying the adhesive.

2. A method according to Claim 1, in which the backing sheet is laminated to the carrier sheet prior to printing the design or designs on the carrier sheet.

3. A method according to Claim 1 or Claim 2, in which the backing sheet and carrier sheet are adhesively laminated.

4. A method according to Claim 3 in which the backing sheet and carrier sheet are laminated by edge glueing.

5. A method according to Claim 4, which includes the step of guillotining the edge portions of the stacked sheets to remove those portions of the backing sheets and carrier sheets which are bonded by edge glueing, thus enabl ing assembled pairs of carrier and backing sheets to be separated from the stack.

6. A method of producing a dry, pressure sensitive adhesive transfer which comprises adhesively laminating a carrier sheet to a back ing sheet having a release surface so that the release surface faces outwardly, printing one or more designs on the exposed surface of the carrier sheet and applying a pressuresensitive adhesive coating onto said designs, the adhesive bond between the carrier and backing sheets being sufficient to maintain the integrity of the laminate during the printing and adhesive coating operauons.

7. A method according to Claim 6, in which the carrier and backing sheets are separable from a stack of such alternate sheets in appropriate pairs by trimming off the adhesive forming the laminate bond or by using a pressure-sensitive adhesive having higher bond strength to the backing sheet than the adhesive bond of the laminate.

8. A method according to Claim 6 or Claim

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. film is obtained having a high gloss finish on one side and a matt finish on the other side. A shearable release layer of our copending application 06068/78 (Serial No. 1,603,972) is coated onto the matt surface of this film by roller coating using a 10% dispersion of stearamide wax in aliphatic hydrocarbon which is dried by hot air jets. The gloss surface of the plastic is laminated to the uncoated, machine glazed side of a backing paper consisting of machine glazed paper of 30 gsm to which a silicone release coating has been applied to the non-glazed side of the sheet by reverse roll coating using a liquid polymerisable silicone solution in organic solvent which has been dried by evaporation and heating to 1200C to further polymerise or cross-link the silicone and render it nonmigrating and insoluble. Lamination is carried out in the nip of a pair of hard rubber rollers and spots of hot melt glue are applied to either the film or paper web by a spot-glue coating wheel prior to the nip. On cooling a good spot-glue bond is formed at 5 mm from the sheet edge with spots of about 2 mm spaced apart by 5 mm and the general adhesion of the gloss/gloss surfaces adequately resists delamination during printing. Example 2. A semi-gloss extruded polystyrenebutadiene copolymer film of 90 rm thickness is coated both sides by roller coating with the shearable release layer of our copending application 06068/78 (Serial No. 1,603,972) using a 20% colloidal dispersion of stearamide wax in aliphatic hydrocarbon. A web of silicone back ing paper is laminated to one side of the wet plastic film by web tension whereby the non silicone side of the backing paper is laminated to the plastic film. After drying using hot air jet at 700C a laminate is obtained having a low peel bond adhesion of about 10 g/cm which resists delamination forces during subsequent printing processes for the preparation of a dry transfer. The accompanying drawings illustrate the production of laminated transfer sheets in accordance with the invention. Referring to the drawings:-- Fig. 1 is a magnified illustration of a carrier sheet (1) having a semi-matt surface (2) and a smooth gloss surface (3). The carrier sheet is laminated to a silicone backing sheet (4) having a smooth machine-glazed surface (5) and a fibrous surface (6) with a silicone coating (7). The two sheets are edge-glued with spots of adhesive (8) and the remainder of the smooth surfaces of the two sheets are in dose physical contact. The exposed surface of the carrier sheet carries an offset litho printed dry ink design as halftone dots (9), a clear high film strength layer (10) applied by screenprinting, a white screenprinting layer (11) and an overlapping low-tack pressure sensitive adhesive layer (12). Fig. 2 illustrates a stack of printed carrier sheets in which the silicone layer (7) is in contact with the pressure sensitive adhesive (12). This assembly is then guillotined to remove the edge-glued spots (8) after a single silicone sheet is placed on the top carrier sheet. The stack of sheets are then readily separated at the interface (13) to produce separate carrier sheets each produced with a backing sheet. WHAT WE CLAIM IS:

1. A method of producing a dry pressure sensitive adhesive transfer wherein one or more transferable deSigns are supported on a carrier sheet and wherein the transfer is laminated to a backing sheet having a release surface, said method comprising laminating the carrier sheet of the transfer, prior to applying the pressure-sensitive adhesive, with a backing sheet having a release surface so that the release surface faces outwardly and applying the pressure-sensitive adhesive to the design or designs on the carrier sheet, the carrier sheet and the backing sheet being separable after drying the adhesive.

8. A method according to Claim 6 or Claim

7 in which the backing sheet is coated on one or both surfaces with release agent.

9. A laminated dry transfer which comprises a carrier sheet having one or more transferable designs on one surface, each design bearing a coating of a pressure-sensitive adhesive and a backing sheet laminated to the other surface of the carrier sheet, the exposed surface of the backing sheet having a release surface.

10. A method of producing a laminated dry transfer substantially as described with reference to the Examples.

11. A stack of laminated dry transfers sub stantially as described with reference to Figure 2 of the accompanying drawings.