Process and materials for thermal imaging

• US 5,024,989 A
• Filed: 04/25/1990
• Issued: 06/18/1991
• Est. Priority Date: 04/25/1990
• Status: Expired due to Fees

• Current Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Gaudiana, Russell A., Chiang, Yunn H.
• Primary Examiner(s): Hess, Bruce H.
• Application Number:
  US07/514,169
• Time in Patent Office: 419 Days
• Field of Search: 8/471, 428/1, 428/195, 428/913, 428/914, 428/336, 428/412, 428/480, 428/500, 503/227, 427/256
• US Class Current: 503/227
• CPC Class Codes: B41M 5/395 Macromolecular additives, e.g. binders
• CPC Class Codes: B41M 5/42 Intermediate, backcoat, or covering layers B41M5/405 takes precedence; multilayer thermal transfer systems in general B41M5/38214
• CPC Class Codes: B41M 5/44 characterised by the macromolecular compounds
• CPC Class Codes: B41M 5/52 Macromolecular coatings
• CPC Class Codes: B41M 5/5254 characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers
• CPC Class Codes: B41M 5/5272 Polyesters; Polycarbonates
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10S 428/914 Transfer or decalcomania
• CPC Class Codes: Y10S 430/142 Dye mordant
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/31507 Of polycarbonate
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers

Abstract

A process for thermal imaging uses a donor sheet and a receiving sheet. The donor sheet comprises a support and a dye capable of being transferred by heat, while the receiving sheet is adapted to receive the dye and thereby form an image. The donor and receiving sheets are placed adjacent one another, and at least one of the adjacent faces of the donor and receiving sheets has a layer of a polymeric liquid crystal thereon. Selected portions of the donor sheet are heated so as to transfer dye from the donor sheet to the receiving sheet, thereby forming an image on the receiving sheet.

Claims

1. A process for thermal imaging using a donor sheet and a receiving sheet, the donor sheet comprising a support and a dye capable of being transferred by heat, the receiving sheet comprising a support and being adapted to receive the dye and thereby form an image, the process comprising placing the donor and receiving sheets adjacent one another, a polymeric liquid crystal being provided on at least one of the donor and receiving sheets so as to be present at the interface between the donor and receiving sheets, and heating selected portions of the donor sheet so as to transfer dye from the donor sheet to the receiving sheet, thereby forming an image on the receiving sheet.

2. A process according to claim 1 wherein the donor sheet comprises a dye layer disposed on one face of the support, the dye layer comprising the dye and a binder for the dye, and during the heating the dye layer on the support faces the receiving sheet.

3. A process according to claim 2 wherein the binder comprises a vinyl alcohol/vinyl butyral copolymer.

4. A process according to claim 2 wherein a layer of a lubricating agent is provided on the face of the donor sheet remote from the dye layer, the lubricating agent serving to reduce adhesion of a thermal printing head to the donor sheet.

5. A process according to claim 1 wherein the receiving sheet comprises the polymeric liquid crystal.

6. A process according to claim 5 wherein the receiving sheet comprises a layer of polymeric liquid crystal layer from about 0.5 to about 10 μ

thick on the support.

7. A process according to claim 6 wherein the polymeric liquid crystal layer on the receiving sheet is from about 1 to about 6 μ

thick.

8. A process according to claim 5 wherein the polymeric liquid crystal comprises a polymeric polyester.

9. A process according to claim 8 wherein the polymeric liquid crystal comprises a polymer of an aliphatic dicarboxylic acid and an aromatic dihydroxylic phenol.

10. A process according to claim 9 wherein the aliphatic dicarboxylic acid comprises azelaic acid and the aromatic dihydroxylic phenol comprises at least one of a methylquinol and 4,4'"'"'-bisphenol.

11. A process according to claim 8 wherein the polymeric liquid crystal comprises a polymer containing residues of an aromatic hydroxy acid or an aromatic dicarboxylic acid and an alkylene glycol.

12. A process according to claim 11 wherein the polymer comprises residues of at least one of p-hydroxybenzoic acid, a phthalic acid, and a halophthalic acid, and residues of ethylene glycol.

13. A process according to claim 5 wherein the polymeric liquid crystal is the only component of the receiving sheet adapted to receive the dye and thereby form an image.

14. A process according to claim 5 wherein the receiving sheet comprises an image receiving material which is not a liquid crystal.

15. A process according to claim 14 wherein the image receiving material comprises an acrylate polymer or a polycarbonate.

16. A process according to claim 15 wherein the image receiving material comprises poly(methyl methacrylate).

17. A process according to claim 1 wherein heating of the donor sheet is effected by means of a thermal printing head which is scanned over a plurality of areas of the donor sheet to effect an imagewise transfer of dye from the donor sheet to the receiving sheet.

18. A process according to claim 17 wherein the duration of contact between the thermal printing head and the various ones of the plurality of areas of the donor sheet is varied to vary the reflectance density of the various parts of the image produced.

19. Sheet material for use in thermal imaging, the sheet material comprising a donor sheet and a receiving sheet, the donor sheet comprising a support and a dye capable of being transferred by heat, and the receiving sheet having on one of its faces an image receiving layer comprising a polymeric liquid crystal.

20. Sheet material according to claim 19 wherein the donor sheet comprises a dye layer disposed on one face of a support, the dye layer comprising the dye and a binder for the dye.

21. Sheet material according to claim 20 wherein a layer of a lubricating agent is provided on the face of the donor sheet remote from the dye layer, the lubricating agent serving to reduce adhesion of a thermal printing head to the donor sheet.

22. Sheet material according to claim 19 wherein the image receiving layer comprises a layer of polymeric liquid crystal from about 0.5 to about 10 μ

thick.

23. Sheet material according to claim 22 wherein the polymeric liquid crystal layer is from about 1 to about 6 μ

thick.

24. Sheet material according to claim 19 wherein the polymeric liquid crystal comprises a polymeric polyester.

25. Sheet material according to claim 24 wherein the polymeric liquid crystal comprises a polymer of an aliphatic dicarboxylic acid and an aromatic dihyroxylic phenol.

26. Sheet material according to claim 25 wherein the aliphatic dicarboxylic acid comprises azelaic acid and the aromatic dihyroxylic phenol comprises at least one of a methylquinol and 4,4'"'"'-bisphenol.

27. Sheet material according to claim 24 wherein the polymeric liquid crystal comprises a polymer containing residues of an aromatic hydroxy acid or an aromatic dicarboxylic acid and an alkylene glycol.

28. Sheet material according to claim 27 wherein the polymer comprises residues of at least one of p-hydroxybenzoic acid, a phthalic acid, and a halophthalic acid, and residues of ethylene glycol.

29. Sheet material according to claim 19 wherein the image receiving layer comprises a mixture of the polymeric liquid crystal and an image receiving material which is not a liquid crystal.

30. Sheet material according to claim 19 wherein the image receiving layer comprises an acrylate polymer.

31. Sheet material according to claim 30 wherein the image receiving layer comprises poly(methyl methacrylate).

32. Sheet material according to claim 19 wherein, in addition to the image receiving layer comprising a polymeric liquid crystal, the receiving sheet comprises a second image receiving layer formed from a material which is not a liquid crystal, this second image receiving layer being in contact with the polymeric liquid crystal layer on the side thereof remote from the surface of the receiving sheet.