WO2001008896A1

WO2001008896A1 - Dye-donor sheet for thermal transfer with vinylidene chloride copolymer binder

Info

Publication number: WO2001008896A1
Application number: PCT/GB2000/002890
Authority: WO
Inventors: Christopher Bennett; Kelvin Patrick Adkins; Michael Robert Dayman
Original assignee: Imperial Chemical Industries Plc
Priority date: 1999-07-09
Filing date: 2000-07-27
Publication date: 2001-02-08
Also published as: GB9917676D0

Abstract

A thermal melt transfer medium for use in mass transfer printing comprises a substrate bearing on at least part of one surface thereof a coating comprising colorant (commonly carbon black), binder an a vinylidene chloride copolymer resin. The resin is conveniently a copolymer of vinylidene chloride/acrylonitrile. One preferred commercially available resin is Saran F310. The resin is found to increase the release force of the coating from the substrate, the substrate preferably bearing a suitable release layer. This increase in release force enables production of clear printed images with well defined sharp edges. The resin has good chemical resistance and toughness and so produces a durable printed image. The invention also concerns a method of making the thermal melt transfer medium, a method of mass transfer printing using the medium and the resulting printed material.

Description

DYE-DONOR SHEET FOR THERMAL TRANSFER WITH VINYLIDENE CHLORIDE COPOLYMER BINDER

Field of the Invention

This invention relates to mass transfer printing and concerns a thermal melt transfer medium, a method of making the medium, a thermal melt transfer medium/receiver combination, a method of mass transfer printing using the medium and the resulting printed material.

Background to the Invention

Mass transfer printing is a well known technique in which colorant material (commonly carbon black) is transferred by localised application of heat from a mass transfer layer of a thermal melt transfer medium to a receiver material. Mass transfer printing is generally used to print monochrome images, commonly text, bar codes etc. Mass transfer printing is often used in conjunction with dye diffusion thermal transfer printing of full colour images, using thermally transferable dyes of the three primary colours, yellow, magenta and cyan, with a common application being the printing of identification cards bearing a full colour image of the head of a person and a monochrome (usually black) bar code Such printing is conveniently carried out using a dye sheet m the form of an elongate strip or ribbon of a heat-resistant substrate, typically polyethylene terephthalate film, carrying a plurality of similar sets of different coloured dye coats and colorant, each set comprising a panel of each dye colour (yellow, magenta and cyan) and a panel of colorant, with the panels being in the form of discrete stripes extending transverse to the length of the ribbon, and arranged in a repeated sequence along the length of the ribbon. The mass transfer layer is capable of being printed directly onto both pre-printed (eg. by thermal dye transfer) and unprinted receiver media. The mass transfer printing can be protected by an optional overlay coating applied as an additional panel or as a separate lamination.

The thermal melt transfer medium comprises a substrate bearing on at least part of one surface thereof a mass transfer layer or coating comprising mass transfer colorant Earl} thermal melt transfer media used a coating comprising a mixture of colorant and wax While these had good pnntabihty with the colorant coating fracturing easily during the printing process and producing clear printed images with well defined shaφ edges the resulting images were of relatively poor durability due to the soft nature of the wax

Image durability can be improved by use of thermal melt transfer media having a coating comprising a mixture of colorant and polymer binder, eg polyester resins vinyl chloride/ vinyl acetate copolymer resins etc The use of such binders produces pπnted images formed of tough cohesiveh strong layers of material having good durability However, the cohesive strength of the materials means that they are difficult to print because the material does not fracture easily during pπnting, instead the material tends to tear or rupture producing images with jagged or ragged edges, exhibiting a phenomenon known as flashing, rather than forming clear images with well defined sharp edges

Summary of the Invention

According to the present invention there is provided a thermal melt transfer medium comprising a substrate beaπng on at least part of one surface thereof a coating comprising colorant, binder and a vinylidene chloride copolymer resin

The resin is conveniently a copolymer of vinylidene chloπde/acrylonitπle

Suitable resins may be made by known techniques, or are commercially available Preferred commercially available resms are Saran F300 and Saran F310 (Saran is a Trade Mark) from Dow Plastics, each of which is a copolymer of vinylidene chloπde/acrylonitπle The two Saran materials are believed to be similar chemicalh A mixture of resins may be used

The resin is suitably present in an amount m the range 5 to 80% , preferably 10 to 50% , typically about 20% by weight of the solids content of the coating In use of the medium the presence of the resin is found to be able to give images of good print definition that have good durability. The resin is reported as having good chemical resistance and toughness. The good print definition obtainable is therefore unexpected, as the resin would not be expected to reduce the cohesive strength of the coating. A marked increase in the release force of the coating from the substrate (possibly bearing a suitable release layer), which is indicative of the adhesive force between the substrate and coating, has been observed. It is this increase in release force that gives good print definition, as will be explained further below.

The colorant may be selected from materials known for this puφose. As noted above, one commonly used colorant is carbon black. Other preferred colorants have strong absorbances in the red and infra red, and phthalocyanine and substituted phthalocyanines are especially preferred. A mixture of colorants may be used.

Colorant is suitably present in an amount in the range 10 to 70% , preferably 20 to 40% , typically about 30% by weight of the solids content of the coating.

The binder is usually in the form of a thermoplastic resin, preferably having a Tg in the range 50 to 180°C. Suitable binder materials are known in the art, eg as disclosed in EP 0283025, and include vinyl chloride/vinyl acetate copolymers, polyester resins, poly vinyl chloride resins, acrylic resins, polyamide resins, polyacetal resins and vinyl resins. A mixture of binders may be used. One currently preferred binder is Vinylite VYHH (Vinylite VYHH is a Trade Mark) which is a copolymer of vinyl chloride/vinyl acetate at weight proportions of 86/14 having an average molecular weight of 20,000 and a Tg of 72°C.

The binder may be selected bearing in mind, inter alia, compatibility with the intended receiver material, eg as discussed in EP 0283025.

The binder is suitably present in an amount in the range 10 to 70%, preferably 20 to 40% , typically about 30% of the weight of the solids content of the coating. It has been found convenient to use carbon black and vinyl chloride/vinyl acetate copolymer binder in the form of Noir PVC 512975 black chips which are commercially available from BASF and which consists of a mixture of equal weights of carbon black and Vmyhte VYHH which have been hot milled together.

The coating of the thermal melt transfer medium may include surfactant to aid dispersion of the colorant in known manner, although this is not generally necessary if the colorant ι<; used in ready-dispersed form as is the case with Noir PVC 512975

The coating of the thermal melt transfer medium optionally includes paniculate material Suitable materials include micromsed polypropylene The paniculate material suitably has a particle size in the range 0 1 to 20 μm Good results have been obtained with Micropro 600VF (Micropro 600VF is a Trade Mark) which is micronised polypropylene having a particle size of about 8 μm Paniculate material can improve wear resistance of the printed image without adversely affecting transfer properties

Paniculate material is suitably present m an amount in the range 1 to 20% , typically about 3 to 10% of the weight of the solids content of the coating

Other materials may optionally be mcluded m the thermal melt transfer medium in known manner

The substrate may be any suitable heat-resistant material such as those known in the art Suitable substrate materials include films of polyesters, polyamides, polyimides polycarbonates, polysulphones, polypropylene and cellophane BiaxialK oriented polyester film, particularly polyethylene terephthalate (PET), is currently favoured for its properties of mechanical strength, dimensional stability and heat resistance The substrate suitably has a thickness in the range 1 to 20μm, preferably 2 to lOμm, typically about 6μm The thermal melt transfer medium preferably includes a subcoat between the substrate and colorant-containing coating, particularly in the form of a releasing subcoat to assist release of the coating during printing. One preferred release subcoat comprises a crosslinked acrylic coating.

The thermal melt transfer medium desirably includes a heat-resistant backcoat, on the side of the substrate not carrying the colorant-containing coating, to resist applied heat in use in known manner.

The thermal melt transfer medium is conveniently in the form of a ribbon for use in thermal transfer printing, comprising a substrate having on one surface thereof a plurality of repeated sequences of dye coats and colorants in the form of discrete stripes extending transverse to the length of the ribbon.

Thus in a preferred aspect the invention provides a thermal melt transfer medium, comprising an elongate strip of substrate material having on one surface thereof a plurality of similar sets of thermally transferable dye coats and mass transfer layers, each set comprising a respective coat of each dye colour, yellow, magenta and cyan, and a mass transfer layer, each coat or layer being in the form of a discrete stripe extending transverse to the length of the substrate, with the sets arranged in a repeated sequence along the length of the substrate, wherein each mass transfer layer comprises a coating comprising colorant, binder and a vinylidene chloride copolymer resin.

The thermal melt transfer medium is conveniently made by mixing together the coating materials (colorant, binder, resin and any optional ingredients such as paniculate material) and dissolving or dispersing the mixture in a suitable solvent as is well known in the art to give a coating liquid. Suitable solvents include butan-2-one, propanone, tetrahydrofuran, toluene, cyclohexanone etc. The coating liquid is then coated on the substrate and dried in known manner eg by bar coating, blade coating, air knife coating, gravure coating, roll coating, screen coating, fountain coating, rod coating, slide coating, curtain coating, doctor coating. The coating suitably has a thickness in the range 0.1 to 5μm, preferably 0.5 to 3μm, typically 1.5 to 2.0μm.

In a further aspect the invention provides a method of making thermal melt transfer medium, comprising forming on one surface of a substrate a coating comprising colorant, binder and a vinylidene chloride copolymer resin.

The thermal melt transfer medium is used in known manner for printing an image on suitable receiver material. The receiver material is typically in the form of a sheet or card of paper, cardboard, plastics material etc having a suitable image-receiving surface. The thermal melt transfer medium is placed in contact with the receiver material and localised heating effected to cause localised transfer of colorant to produce a desired image, such as text or a barcode, on the receiver material. When used in conjunction with thermal transfer printing of dyes, as discussed above, a full colour image may also be produced on the receiver material. One common use of the thermal melt transfer medium is in production of identification cards, typically formed on a sheet of plastics material such as poly vinyl chloride, ABS (acrylonitrile-butadiene-styrene) or polyester, and which may bear a full colour photograph of the head of an individual, produced by thermal transfer printing, in combination with text and/or a bar code produced by mass transfer printing of colorant.

In a further aspect the invention provides a thermal melt transfer medium/receiver combination, wherein the thermal melt transfer medium comprises a substrate bearing on at least part of one surface thereof a coating comprising colorant, binder and vinylidene chloride copolymer resin, and the receiver comprises a sheet of material having an image- receiving surface.

The binder and receiver are preferably selected for compatibility in use, eg with a binder and image-receiving surface of the receiver being chemically similar. For example, good results have been obtained using a binder comprising a copolymer of vinyl chloride/vinyl acetate, eg in the form of Vinylite VYHH, with a receiver eg of poly vinyl chloride, having an image-receiving surface comprising vinyl chloride/vinyl acetate copolymer: these materials are chemically very similar and give rise to a high adhesive force between the receiver and colorant-containing coating material, resulting in good adhesion of colorant to the receiver.

The thermal melt transfer medium is preferably such that the adhesive force between the colorant-containing coating material and the underlying substrate (or subcoat thereon) is suitably high to be able to retain colorant on the substrate in non-printed (cold) regions, enabling the coating to shear cleanly at the boundaries between printed (hot) regions and unprinted (cold) regions. In this way, printed images having well defined shaφ edges, ie having good print resolution, can be obtained. Good results have been obtained with a receiver having a vinyl chloride/vinyl acetate copolymer image-receiving surface and a thermal melt transfer medium comprising a substrate with a crosslinked acrylic subcoat bearing a coating comprising colorant, vinyl chloride/vinyl acetate copolymer binder and a vinylidene chloride copolymer resin. The vinylidene chloride copolymer resin acts to increase the adhesive force of the colorant-containing coating material with the substrate subcoating, thus improving print resolution as explained above. The vinylidene chloride copolymer resin also acts to impart chemical resistance and toughness to the print, giving good image durability.

In a preferred aspect, the invention provides a thermal melt transfer medium/receiver combination, wherein the thermal melt transfer medium comprises a substrate with a cross- linked acrylic subcoat bearing a coating comprising colorant, vinyl chloride/vinyl acetate binder and a vinylidene chloride copolymer resin, and the receiver has an image-receiving surface comprising vinyl chloride/vinyl acetate copolymer.

In a further aspect the invention provides a method of mass transfer printing comprising supeφosing a thermal melt transfer medium in accordance with the invention and a receiver material; applying localised heating to the thermal melt transfer medium to produce a printed image on the receiver material. The invention also includes within its scope the receiver material after printing, particularly an identification card bearing a full colour image produced by thermal transfer pπnting and text and/or a bar code produced by mass transfer printing of colorant

The invention will be further described, by way of illustration, in the following examples

Examples

Example 1 (Comparative)

A coating solution (solution A) was prepared from

Noir PVC 512975 10% by weight Butan-2-one 90% by weight

A coating was applied by hand using a Meier bar, to give a wet film thickness of 12μm, onto a 6μm polyester substrate base film, coated with a back coat to resist the thermal head during printing and a subcoat comprising a crosslinked acrylic system to provide release during printing The wet coating was dried in an oven at 110°C for 30 seconds

The subcoat comprises a highly cross-linked acrylic coating in which the cross-linking is achieved by UV-curing using a combination of photoinitiators and synergists included in the subcoat composition, details of which are given below. The subcoat was coated on the polyester to give a dry coat thickness of approximately 0.5μm. The subcoat composition, expressed as % w/w, was as follows:

MIBK is methyl iso-butyl ketone This is the solvent from which the subcoat layer is deposited The solvent is evaporated from the coating before it is subjected to UV-cuπng

Uvecryl E1354 is a hexafunctional aromatic urethane acrylate oligomer (Uvecryl is a

Trade Mark )

Diakon MG102 is a high molecular weight grade of poly methylmethacrylate (Diakon is a Trade Mark )

Irgacure 907, Uvecryl PlOl, Quantacure ITX & Quantacure EPD catalyse UV-cuπng of the Uvecryl E1354 (Irgacure, Uvecryl and Quantacure are Trade Marks.)

The resulting thermal melt transfer medium was used to print onto a receiver comprising a card of polyvinyl chloride (PVC) The surface of the PVC card consists predominantly of a vmyl chloπde/vmyl acetate copolymer (approximately 95 5 ratio, respectively) Printing was carried out using a Fargo Pro card printer (Fargo Pro is a Trade Mark) (manufactured by FARGO Electronics Incoφorated)

The image was assessed for prmt quality, which was very poor the bars and characters had ragged edges caused by the black layer sticking m unprmted areas and there was filling in between bars The image was also assessed for print quality using the print sensitivity test (described below) and gave an area fraction of 0 17 black to white ratio The printed card was then tested for durability using a tumble test (described below) and gave a good result there being essentially no visible damage to the printed image

The coating was also tested for release force of the coating from the substrate usmg the release force test described below The release force of this coating was 0.38 N/50mm Example 2

A coating solution (solution B) was prepared from

Noir PVC 512975 8 7% by weight

Saran F310 1 3 % by weight ( 15 % w/w on Noir PVC)

Butan-2-one 90% by weight

A coating was applied and printed as described m Example 1

The image was assessed for prmt quality which was very good, there being no loose material and no fill in The image was also assessed for print quality using the print sensitivity test and gave an area fraction of 0 11 black to white ratio The printed card was then tested for durability using the tumble test and gave a good result, there being essentially no visible damage to the prmt image

The coating was also tested for release force The release force of this coating was 0 93 N/50mm

Further solutions were prepared, as for Solution B, in which the level of Saran F310 wa? varied from 0 to 20% w/w on Noir PVC These were coated and assessed for print quality, release force and durability The results are summarised m Table 1 below

Example 3

A coating solution (solution C) was prepared from

Noir PVC 512975 8 7% by weight

Saran F300 1 3% by weight (15% w/w on Noir PVC)

Butan-2-one 90% by weight A coating was applied and printed as described in Example 1.

The image was assessed for print quality which was very good, there being no loose material and no fill in. The image was also assessed for print quality using the print sensitivity test and gave an area fraction of 0.13 black to white ratio. The printed card was then tested for durability using the tumble test and gave a good result, there being essentially no visible damage to the print image. The results are summarised in Table 1 (below).

The coating was also tested for release force. The release force of this coating was 0.85N/50mm..

Table 1

* Print Quality and Tumble Test grades: 1 = excellent, 5 = bad ** Example 3 using Saran 300

Examples 2 and 3 show that the Saran F300 and Saran F310 act to increase the release force, indicative of the adhesive force between the coating and the substrate. This force is increased to a point where it is suitably high to be able to retain colorant material in non- printed (cold) regions, accounting for the observed increase in print quality. The Saran resins have good chemical resistance and toughness, and do not compromise image durability, as indicated by the tumble test results.

Example 4

A thermal melt transfer medium was prepared as described in Example 2. This was used to print (using a Fargo Procard printer as used in Example 1) onto a receiver comprising a voided polyester substrate coated with a receiving layer comprising a saturated polyester resin with a polysiloxane release agent. The receiver substrate is a white biaxially orientated polyethylene terephthalate polyester film (Mehnex 990 from Dupont). The receiver layer comprises a synthetic polyester resin (Vylon 200 from Toyobo) with a polydimethyl siloxane release agent (Tegomer H-SI 2210 from Th. Goldschmidt) with a modified melamine-formaldhyde crosslinker (Cymel 300 from Dyno Cytec K.S.). Melinex, Vylon, Tegomer and Cymel are Trade Marks.

The image was assessed for print quality which was very good, there being no loose material and no fill in. The image was also assessed for print quality using the print sensitivity test (described below) and gave an area fraction of 0.12 black to white ratio. The printed card was then tested for durability using the tumble test and gave a good result, there being essentially no visible damage to the print image.

The coating was also tested for release force. These release force of this coating was 0.92N/50mm.

Tumble Test for Durability

The object of this test is to simulate the sort of everyday wear that a card could be subjected to. This included flexing, handling, high humidity and abrasion by coins, etc

After printing, samples are flexed 100 times along the length of the card (image extension). After applying Veriderm grease (a hand cream which mimics finger grease, manufactured by Upjohn) (Veriderm is a Trade Mark) to the image surface the samples are placed in a 45°C/85 %RH (relative humidity) oven for 24 hours. The cards are then placed around the inside (facing inwards) of a plastic cylindrical container which contains a selection of washers, nuts and bolts. A lid is placed onto the container and the whole is tumbled on a roller at a speed of 20 φra for two hours. Samples are removed and assessed according to the extent of damage to the image. Good samples show no visual damage and bad samples may be completely worn away.

Release Force Test

The release force test is designed to measure the force required to peel the colorant- containing coating material from the releasing subcoat. The test is carried out in two stages: A. Sample preparation, followed by B. Measurement of release force:

A. Sample preparation

An in-house designed printer is used to print three rectangular areas of colorant material in sequence onto the card receiver. The geometry of the thermal print head is arranged in such a way that the colorant material adheres to the receiver surface but does not release from the ribbon at this stage. This provides a test sample consisting of ribbon which is adhered to the PVC card by the colorant material in the printed regions. A length of ribbon is left unprinted to provide a leader for attachment to a strain gauge in the next stage of the test.

B. Measurement of release force.

This part of the test is carried out under controlled conditions of temperature and humidity. mn(20^cC and 60% relative humidity). Measurements are carried out on a test rig attached to an Instron 6021 instrument manufactured by Instron Limited (Instron is a Trade Mark).

The PVC card is fixed to a horizontal support plate with the adhered ribbon uppermost. The free end of the ribbon is attached to a force gauge and force applied in a vertical direction to peel the ribbon from the card at speed of 2 mm s. The colorant material releases from the subcoat and remains adhered to the card surface as the ribbon is peeled away from the card. The Instron instrument records the force required to separate the colorant material from the subcoat layer.

The release force is expressed as the average of the forces required to peel three printed regions.

Print Sensitivity Test

Bar code readability and text legibility are important factors in melt transfer printing. This print sensitivity test uses a video camera and an image analysis system to measure the print ratio (black to white ratio) of a test image of pixel lines.

An image analysis system comprising both hardware and software (Mini Magiscan IAS25/IV25 supplied by Joyce-Loebl Ltd.) with associated microscope, fibre-optic lighting, video camera, monitor and PC is used to measure the area fraction of the printed lines to the white unprinted area. Five cards should be printed with an image of fine lines (pixel ratio of 1 :4 black to white). Four measurements should be made for each sample.

Area fraction values Print Quality

Less than 0.10 Poor, very thin and light

0.10 to 0.13 Good

Greater than 0.13 Poor, thick lines and fill in of characters

Claims

1. A thermal melt transfer medium comprising a substrate bearing on at least one part of one surface thereof a coating comprising colorant, binder and a vinylidene chloride copolymer resin.

2. A thermal melt transfer medium according to claim 1, wherein the resin is a copolymer of vinylidene chloride/acrylonitrile.

3. A thermal melt transfer medium according to claim 2, wherein the resin comprises Saran F300 and/or Saran F310.

4. A thermal melt transfer medium according to any one of the preceding claims, wherein the resin is present in an amount in the range 5 to 80%, preferably 10 to 50% , typically about 20% by weight of the solids content of the coating.

5. A thermal melt transfer medium according to any one of the preceding claims, wherein the colorant comprises one or more of carbon black, phthalocyanine and substituted phthalocyanines.

6. A thermal melt transfer medium according to any one of the preceding claims, wherein colorant is present in an amount in the range 10 to 70%, preferably 20 to 40%, typically about 30% by weight of the solids content of the coating.

7. A thermal melt transfer medium according to any one of the preceding claims, wherein the binder is in the form of a thermoplastic resin, having a Tg in the range 50 to 180°C.

8. A thermal melt transfer medium according to any one of the preceding claims, wherein the binder comprises one or more of vinyl chloride/vinyl acetate copolymers, polyester resins, poly vinyl chloride resins, acrylic resins, polyamide resins, polyacetal resins and vinyl resins.

9. A thermal melt transfer medium according to any one of the preceding claims, wherein the binder is present in an amount in the range 10 to 70%, preferably 20 to 40% , typically about 30% of the weight of the solids content of the coating.

10. A thermal melt transfer medium according to any one of the preceding claims, wherein the colorant comprises carbon black and the binder comprises vinyl chloride/vinyl acetate.

11. A thermal melt transfer medium according to any one of the preceding claims, wherein the coating further comprises surfactant.

12. A thermal melt transfer medium according to any one of the preceding claims, wherein the coating further comprises paniculate material.

13. A thermal melt transfer medium according to claim 12, wherein the paniculate material has a particle size in the range 0.1 to 20μm.

14. A thermal melt transfer medium according to claim 12 or 13, wherein the paniculate material comprises micronised polypropylene.

15. A thermal melt transfer medium according to claim 12, 13 or 14, wherein the paniculate material is present in an amount in the range 1 to 20% , typically about 3 to 10% of the weight of the solids content of the coating.

16. A thermal melt transfer medium according to any one of the preceding claims, wherein the substrate comprises a film of heat-resistant material selected from polyesters, polyamides, polyimides, polycarbonates, polysulphones, polypropylene and cellophane.

17. A thermal melt transfer medium according to any one of the preceding claims, wherein the coating has a thickness in the range 0.1 to 5μm, preferably 0.5 to 3μm, typically 1.5 to 2.0μm.

18. A thermal melt transfer medium according to any one of the preceding claims, further comprising a subcoat between the substrate and colorant-containing coating.

19. A thermal melt transfer medium according to claim 18, comprising a cross-linked acrylic subcoat.

20. A thermal melt transfer medium according to any one of the preceding claims, wherein the other surface of the substrate has a heat-resistant backcoat.

21. A thermal melt transfer medium, comprising an elongate strip of substrate material having on one surface thereof a plurality of similar sets of thermally transferable dye coats and mass transfer layers, each set comprising a respective coat of each dye colour, yellow, magenta and cyan, and a mass transfer layer, each coat or layer being in the form of a discrete stripe extending transverse to the length of the substrate, with the sets arranged in a repeated sequence along the length of the substrate, wherein each mass transfer layer comprises a coating comprising colorant, binder and a vinylidene chloride copolymer resin.

22. A method of making a thermal melt .transfer medium, comprising forming on one surface of a substrate a coating comprising colorant, binder and a vinylidene chloride copolymer resin.

23. A method of mass transfer printing comprising supeφosing a thermal melt transfer medium in accordance with any one of claims 1 to 21 and a receiver material; applying localised heating to the thermal melt transfer medium to produce a printed image on the receiver material.

24. Receiver material bearing a printed image produced by the method of claim 23.

25. Receiver material according to claim 24, in the form of an identification card bearing a full colour image produced by thermal transfer printing and text and/or a bar code produced by mass transfer printing of colorant.

26. A thermal melt transfer medium/receiver combination, wherein the thermal melt transfer medium comprises a substrate bearing on at least part of one surface thereof a coating comprising colorant, binder and vinylidene chloride copolymer resin, and the receiver comprises a sheet of material having an image-receiving surface.

27. A thermal melt transfer medium/receiver combination, wherein the thermal melt transfer medium comprises a substrate with a cross-linked acrylic subcoat bearing a coating comprising colorant, vinyl chloride/vinyl acetate binder and a vinylidene chloride copolymer resin, and the receiver has an image-receiving surface comprising vinyl chloride/vinyl acetate copolymer.