GB2049554A

GB2049554A - Transfer printing of films, sheets and foils

Info

Publication number: GB2049554A
Application number: GB7917443A
Authority: GB
Original assignee: WOON WAI TSE
Current assignee: WOON WAI TSE
Priority date: 1979-05-18
Filing date: 1979-05-18
Publication date: 1980-12-31
Also published as: GB2049554B

Abstract

A process for the transfer printing of plastics material in the form of a film, foil, tape or sheet, employing a temporary support carrying sublimable colouring material which is to be printed, involves forming an assembly of the plastics material, and the temporary support, with the colouring material-carrying face of the temporary support in direct contact with a surface of the plastics material, and effecting heating of the assembly through a sheet of material which is applied against that surface of the plastics material opposite to the surface in contact with the temporary support.

Description

SPECIFICATION Transfer printing of films, sheets and foils This invention relates to a process for the transfer printing of plastics material in the form of a film, foil, tape or sheet (hereinafter referred to simply as a film).

By transfer printing of material I mean a process involving the use of a temporary support, for example a sheet of paper or regenerated cellulose or an aluminium foil, on which has been applied, for example by printing, one or more colouring materials in a pattern which it is desired to print onto the material, which method comprises arranging the temporary support with its colouring materialcarrying face in contact with the material to be transfer printed, and applying heat and contact pressure to the assembly to cause the colouring material(s) to sublime into the vapour phase and be absorbed by the material. The colouring material(s) used in transfer printing are usually disperse dyes, but it is within the scope of the present invention to employ other colouring materials on the temporary support, for example certain pigments and colour plastics.An example of a temporary support for use in transfer printing is described in British Patent Specification No. 1,342,304.

The possibility of transfer printing of films has been mentioned briefly in the patent literature in specifications concerned mainly with the transfer printing of fabrics, see for example British Patent Specification No. 1,189,026. However transfer printing processes which are suitable for fabrics are not automatically suitable for the transfer printing of films of plastics materials for various reasons. Thus, the heat required to sublime the colouring material(s) often causes the film to become tacky and adhere to the contact equipment andlor to the temporary support with the result that the film is spoilt when it is separated from the contact equipment or the temporary support. Furthermore, shrinkage of the film caused by the heat used during the transfer printing process often results in an unfaithful transfer of the pattern from the temporary support to the film.

The present invention aims to provide a process forth transfer printing of film whereby the abovementioned difficulties are overcome.

According to the invention a process for the transfer printing (as hereinbefore defined) of a film (as hereinbefore defined) comprises effecting the heating of the assembly of the film and the temporary support through a sheet of material which is applied against that surface of the film which is opposite to the surface in contact with the temporary support.

In order to facilitate the ensuing description, that surface of the film against which said sheet of material is applied will be referred to as the "back surface" and that surface in contact with the temporary support will be referred to as the "front surface".

In conventional transfer printing processes, heating of the colouring material(s) on the temporary support is effected by means of a heating member, for example an iron, heated platen or heated drum, applied against the temporary support, the surface of the material being printed which is remote from the temporary support possibly being supported by a non-heated member. In the process according to the present invention, it is the back surface of the film which is first heated by means of a heating member, and this gives rise to various embodiments of the process.

In a first embodiment ofthe process according to the invention, said sheet of material is a loose sheet which is formed into a sandwich with the film and the temporary support. The sheet of material is then heated to such a temperature that the back surface of the film is raised to such a temperature, at or close to the melting point of the film, that the back surface is made sufficiently tacky to adhere to the sheet of material, whereas the front surface of the film is not rendered tacky so that the film absorbs the colouring material(s) from the temporary support without adhering to the latter. In this way a laminate is formed of the sheet of material and the film during the transfer printing process.

This first embodiment of the process according to the invention may be performed in a press or calender such as is used for conventional transfer printing processes, with the temperature of the heating member of the press or calender carefully adjusted to produce the required temperature difference between the back and front surfaces of the film. The temperature of the heating member has to be established for each individual case, having regard to the thickness and nature of the sheet of material, the thickness and nature of the film, the sublimation temperature(s) and diffusion rate(s) of the colouring material(s) used, the formulation(s) of the colouring material(s) and the contact pressure used.

The sheet of material employed in this first embodiment of the process according to the invention may be a woven or non-woven textile fabric, paper or metallic material.

In a second embodiment of the process according to the invention, said sheet of material is raised to a temperature which is insufficient to render the back surface of the film tacky. In this embodiment, the sheet of material is not laminated to the film during the transfer printing process. However, a textured surface on the sheet of material can be used to provide an embossed effect on the film due to the contact pressure employed during the transfer printing process. Suitable sheets of material for use in this second embodiment of the process according to the invention are a silicone coated paper, a flockcovered paper or fabric, a fabric with a special weave structure, or a sheet of metallic or plastics material pre-engraved with a desired embossing motive.The sheet of material may be a loose sheet, as in the first embodiment, which is assembled into a sandwich with the film and the temporary support. Alternatively, the sheet of material may be secured to, or form a permanent part of, the heating member of the press or calender in which the transfer printing process is performed.

The preferred films for transfer printing by the process according to the invention are films of synthetic polymeric material, examples of which are given in the ensuing Examples. Preferably, the films have a thickness of from 0.01 to 5 mm, and preferably transparent and uncoloured films are used.

However, the films may contain plasticisers, stabilisers and other additives conventionally found in synthetic polymeric film material at present available on the market.

Preferred colouring materials for use in the process of the invention are any of the disperse dyes listed in the Colour Index published by the Society of Dyers and Colourists. Of these, the preferred dyes are those which are non-polar, free from sulphonic groups, have a molecular weight of from 200 to 340 and which sublime at a temperature above 1 500C, for example in the range of from 1600 to 240 C.

The invention will now be illustrated by the following non-limitative Examples, in which parts are expressed as parts by weight.

Example 1 Atemporary support was prepared by printing a pattern on a paper sheet using the following three ink formulations:-- (1) Ethanol ..................................... 550 parts Ethyl glycol ..................................... 70 parts Ethyl cellulose ................................. 30 parts "Resiren" Yellow TR-P disperse dye ........................................ 100 parts (2) As (1), but with the "Resiren" dye replaced by 75 parts of "Transetile" Orange GR disperse dye.

(3) As (1), but with the "Resiren" dye replaced by 100 parts of "Dispersol" Yellow A-G TP dis perse dye.

("Resiren", "Transetile" and "Dispersol" are Trade Marks).

When the support paper had dried, its printed face was placed in contact with the front surface of a transparent film and the back surface of the film was placed in contact with a sheet of white cotton fabric weighing 110 g/m2. The assembled material was placed in a transfer press so that during application of heat and pressure thereto the cotton fabric was in contact with the heated plate of the press whereas the support paper was in contact with the supporting table of the press.

Various types of transparent films were employed in this Example, the conditions employed in the transfer press being given in the following Table 1: Table 1 Fllm material Film Range of Range of Contact thickness temperatures pressing pressure (mien) of press times ' (glcm) plate employed employed { CI (sects) Rigid polyvinyl 0.05 190-200 2030 80 chloride (PVC) Non-rigid PVC 0.1 210-225 20-60 60 Non-rigid PVC 3 220-230 10-30 150 Polyethylene 0.01 210-220 20-40 120 Polypropylene 2 270-280 30-60 200 Polyethylene 1.5 270-280 60-80 220 terephthalate Polyurethane 1 160-180 20-30 40 elastomer Cellulose 2.2 170-190 20-30 90 acetate Ethyl cellulose 1.2 190-210 20-30 100 Nylon 6 1.2 250-260 40-60 60 After the prescribed pressing time, the assembly was removed from the press. In each case the support paper was easily separated from the film without any damage to the latter. Excellent transfer of the pattern from the support paper to the film was obtained and in each case the film had been firmly laminated to the white cotton fabric.

After the combined transfer printing and laminating operation, the PVC/cotton fabric laminates were pressed with a hot metal die to give them an embossed effect.

Example 2 The transfer printing and simultaneous lamination process of Example 1 was repeated with seven sheets of transparent PVC film having a thickness of 0.14 mm each assembled with the temporary support paper prepared as in Example 1 and a different one of each of the following backing sheet materials:- a black cotton poplin weighing 110 g/m?, a pink and blue striped woven linen weighing 305 g/r, a polyester filamenttricotweighing 70 g/rr, a wool gabardine weighing 287 g/m2, a backing paper 0.06 mm thick, a viscose non-woven fabric weighing 60 g/m2 and an adhesive coated bronze sheet 0.05 mm thick.During the transfer printing of each of these assemblies, the heated plate of the transfer press was at a temperature of 220 C, the contact time was 20 seconds and the contact pressure 120 g/cm2.

In each case the film was excellently transfer printed and firmly laminated to the backing sheet.

Example 3 The support paper prepared as in Example 1, a transparent PVC film having a thickness of 0.3 mm and a white cotton fabric weighing 110 g/nÇ were assembled together as described in Example 1. The assembly was then passed through a continuous transfer calender with the white cotton fabric in contact with the heated drum, which was at a temperature of 220 C. The speed of the calender was such that the pressing time therein was about 30 seconds, and the contact pressure applied by the calender was about 100 g/cm2. On leaving the transfer calender the support paper separated easily from the film without any damage to the latter. An excellent transfer of the pattern from the support paper to the film was obtained and the film was simultaneously laminated to the white cotton fabric.

Example 4 A temporary support was prepared by printing a pattern on paper strip using the following four ink formulations:-- (1) Ethyl cellulose ........................................ 200 parts Methylated spirit ........................................... 500 parts Isopropyl alcohol ......................................... 100 parts Toluene ........................................................ 200 parts "Dispersol" Yellow A-G TP disperse dye ........................................ 80 parts (2) As (1), but with the "dispersol" dye replaced by 80 parts of "Dispersol" Red B - 2BTP disperse dye.

(3) As (1), but with the "Dispersol" dye replaced by 80 parts of "Foron" Dark Blue E - 2RL disperse dye.

j4) As (1), but with the "dispersol" dye replaced by 80 parts of "Artisil" Violet 2RP disperse dye.

("Foron" and "Artisil" are Trade Marks).

The printed face of the support paper was placed in contact with the front surface of a transparent film and the back surface of the film was placed in contact with a sheet of white polyester knitted fabric with a rib structure, weighing 90 g/m2. The assembled material was placed in a transfer press and during transfer printing of the film the temperature of the heated plate of the press was maintained below the melting point of the film. During the printing the polyester fabric was in contact with the heated plate of the press and the support paper was in contact with the supporting table of the press.

Various types of transparent films were employed in this Example, the conditions employed in the transfer press being given in the following Table 2: Table2 Film material Film Range of Range of Contact thickness temperatures pressing pressure (mien) ofpress times ' (g,c6i) plate employed employed { CJ (sect) Rigid PVC 0.05 140-150 3040 75 Non-rigid PVC 0.1 160-180 25-30 80 Non-rigid PVC 3 170-190 5-20 120 Polypropylene 2 200-210 2040 50 Cellulose acetate 2.2 130-150 20-60 150 Ethyl cellulose 1.2 140-160 2040 90 Nylon 6 1.2 200-210 40-60 100 Low density poly- 0.01 160-180 3040 110 ethylene Polyethylene 1.5 200-210 60-80 150 terephthalate Polymethyl 3 140-160 20-30 80 methacrylate Polystyrene 2 190-210 3040 100 Polyurethane 1 130-150 20-30 40 elastomer Vinylidenechloridel 1.2 135-145 60-120 90 vinylchloride copolymer Acrylonitrile- 1.2 170-190 20-30 80 butadiene styrene Cellulosetriacetate 2 180-200 60-80 190 "Kapton" (Trade 2 200-210 50-60 100 Mark) polyimide Polyvinyl alcohol 1.5 160-180 30-60 90 Polyethylene oxide 1.5 190-210 3040 100 Modacrylic 1.5 200-210 30-60 150 "Flexiglas" (Trade 0.25 170-190 3040 120 Mark) polyacrylic Polyethylenetere- 0.3 180-200 3040 70 phthalate/cyclohexylene dimethanol polyester After the prescribed pressing time, the assembly was removed from the press. Both the support paper and the backing sheet of polyester fabric separated easily from the film without damage to the latter.

Excellent transfer of the pattern from the support paper to the film was obtained without any significant shrinkage of the film and the latter was embossed with the rib structure of the polyester fabric.

Example 5 The printed face of the support paper of Example 4 was placed in contact with the front surface of a transparent PVC film having a thickness of 0.14 mm and the back surface of the film was placed in contact with a silicone coated paper having a thickness of 0.08 mm. The assembly was transfer printed in a transfer press with the silicone coated paper in contact with the heated plate of the press, the latter being maintained at atemperature of 1800C. The pressing time in the press was 20 seconds and the contact pressure used was 80 g/cm2. At the end of the printing process both the support paper and the silicone coated paper separated easily from the film without damage to the latter. Excellent transfer of the pattern from the support paper to the film was obtained, without any significant shrinkage of the latter, and the film had smooth back and front surfaces.

Example 6 Example 5 was repeated using a flock covered cotton fabric weighing 140 glum2 in place of the silicone coated paper. The press conditions were: temperature of the heated plate - 205"C, pressing time - 20 seconds and contact pressure - 100 glum2. At the end of the printing process both the support paper and the cotton fabric separated from the film without damage to the latter and leaving a thin layer of flock sticking to the back surface of the film giving it a velvet appearance. Excellent transfer of the pattern from the support paper to the film was obtained, without any significant shrinkage of the latter.

Claims

1. A process for the transfer printing (as hereinbefore defined of a film (as hereinbefore defined), comprising effecting the heating of the assembly of the film and the temporary support through a sheet of material which is applied against that surface of the film opposite to the surface in contact with the temporary support.

2. A process according to claim 1, wherein the temperature of the surface of the film in contact with said sheet of material is maintained at or above the melting point of the film during the transfer printing, whereas the temperature of the surface of the film in contact with the temporary support is maintained below the melting point of the film, whereby the sheet of material becomes laminated to the film.

3. A process according to claim 1, wherein the temperature of both surfaces of the film is maintained below the melting point of the film during the transfer printing, whereby the sheet of material separates from the film after the transfer printing of the latter.

4. A process according to claim 3, wherein the sheet of material has a textured surface to impart an embossed effect to the transfer printed film.

5. A process according to claim 3 or 4, wherein the sheet of material is secured to, or forms a permanent part of, the heating member of a press or calender in which the transfer printing operation is performed.

6. A process according to any of the preceding claims, wherein the film is of synthetic polymeric material.

7. A process according to claim 6, wherein the synthetic polymeric material comprises any of those given in any ofthe foregoing Examples.

8. A process according to any of the preceding claims, wherein the film has a thickness of from 0.01 to 5 mm.

9. A process according to any of the preceding claims, wherein the film is transparent.

10. A process according to any of the preceding claims, wherein the film is coloured.

11. A process according to any of the preceding claims, wherein said sheet of material comprises a woven, non-woven or knitted fabric of natural or synthetic fibre, a coated or non-coated paper or an engraved or smooth metallic sheet.

12. A process according to any of the preceding claims, wherein the temporary support used comprises an aluminium foil or a sheet of paper or regenerated cellulose.

13. A process according to any of the preceding claims, wherein the colouring material(s) on the temporary support is or are selected from the group consisting of disperse dyes, pigments and colour plastics.

14. A process according to any of claims 1 to 12, wherein the or each colouring material on the temporary support is or comprises a disperse dye having a molecular weight of from 200 to 340 and a sublimation temperature of from 1 50" to 240"C.

15. A process for the transfer printing (as hereinbefore defined) of a film (as hereinbefore defined) substantially as described in any of the foregoing Examples 4 to 6.

16. A film (as hereinbefore defined) when transfer printed by the process claimed in any claims 1, 3 to 5, 6 to 14 when dependent on any of claims 3 to 5, and 15.

17. A process for the transfer printing (as hereinbefore defined) of a film (as hereinbefore defined) and its simultaneous lamination to other material substantially as described in any of the foregoing Examples 1 to 3.

18. A film (as hereinbefore defined) when transfer printed and simultaneously laminated to other material by the process claimed in any of claims 2, 6 to 14 when dependent on claim 2, and 17.

Application No.79 17443 New claims or amendments to claims filed on 28 Feb. 1980 Superseded claim 1

1. A process for the transfer printing (as hereinbefore defined) of a film (as hereinbefore defined), comprising forming an assembly of the film and the temporary support with the colouring material-carrying face of the temporary support in direct contact with a surface of the film, and effecting the heating of the assembly of the film and the temporary support through a sheet of material which is applied against that surface of the film opposite to the surface in contact with the temporary support.