Laser thermal color donors with improved aging characteristics
View Patent ↗A donor element for proofing having at least a transfer material disposed on a substrate for the preparation of a digital halftone proof having consistent dot density characteristics over time. The donor element includes a transfer material having a donor binder, a cationic infrared absorbing dye, a thermally activated crosslinking agent and a dispersible material The donor element can also include a distinct, intermediate transfer layer disposed between the substrate and the transfer material. The donor element can be used in conjunction with a receptor element to provide a thermal imaging system.
1. A donor element comprising
a donor substrate coated with a transfer layer having
a donor binder;
a cationic infrared absorbing dye;
a thermally activated crosslinking agent of the formula
wherein n is 1-50, R 1 is CH 2 or CH 2 OCH 2 at either an ortho- or para-position, R 2 is alkyl at the meta-position when R 1 is para or alkyl at the para-position when R 1 is ortho- and R 3 is independently hydrogen or butyl; and
a dispersible material.
2. The donor element of claim 1 wherein the transfer layer further comprises a fluorocarbon additive.
3. The donor element of claim 2 wherein the fluorocarbon additive comprises a sulfonamido compound.
4. The donor element of claim 2 wherein the fluorocarbon additive comprises (C 8 F 17 )SO 2 NH(CH 2 CH 3 ).
5. The donor element of claim 2 wherein the fluorocarbon additive is present in an amount of from about 0.5 to about 5 wt-% based on the total weight of the transfer layer.
6. The donor element of claim 1 wherein the transfer layer further comprising coating aids, dispersing agents, optical brighteners, UV absorbers, fillers, surfactants, plasticizers or combinations thereof.
7. The donor element of claim 1 wherein the donor binder comprises a hydroxylic polymer.
8. The donor element of claim 1 wherein the donor binder is polyvinyl butyral.
9. The donor element of claim 1 wherein the donor binder is present in an amount of from about 20 to about 50 wt-% based upon the weight of the transfer material.
10. The donor element of claim 1 wherein the cationic infrared absorbing dye is a bleachable dye.
11. The donor element of claim 1 wherein the cationic infrared absorbing dye is a tetraarylpolymethine dye, an amine cation radical dye, or mixtures thereof.
12. The donor element of claim 1 wherein the cationic infrared absorbing dye is a tetraarylpolymethine dye.
13. The donor element of claim 1 wherein the cationic infrared absorbing dye is present in an amount of from about 5 to about 20 wt-% based on total weight of the transfer layer.
14. The donor element of claim 1 wherein the thermally activated crosslinking agent is of the formula
wherein n is 1-50 and R 2 can be independently hydrogen or alkyl.
15. The donor element of claim 1 wherein the thermally activated crosslinking agent is of the formula
wherein n is 1-50 and R 2 can be independently hydrogen or alkyl.
16. The donor element of claim 1 wherein the thermally activated crosslinking agent is present in an amount of from about 1 to about 10 wt-% based on the total weight of the transfer layer.
17. The donor element of claim 1 wherein the dispersible material is a pigment, a crystalline nonsubliminable dye, a color enhancing additive, a texturizing material, or mixtures thereof.
18. The donor element of claim 1 wherein the dispersible material comprises a pigment.
19. The donor element of claim 1 wherein the dispersible material comprises a cystalline nonsubliminable dye.
20. The donor element of claim 1 wherein the dispersible material comprises metallic flakes.
21. The donor element of claim 1 wherein the dispersible material is present in an amount of from about 15 to about 50 wt-% based on the total weight of the transfer layer.
22. The donor element of claim 1 wherein the transfer material further comprises a crosslinking agent of the formula
wherein R 1 is hydrogen, alkyl, cycloalkyl or aryl, R 2 and R 3 are independently alkyl or aryl and R 4 is aryl.
23. The donor element of claim 1 wherein the donor element material further comprises an intermediate transfer layer disposed between the substrate and the transfer layer having
an intermediate layer donor binder; and
a cationic infrared absorbing dye.
24. A thermal imaging system comprising
a donor element comprising a donor substrate coated with a transfer layer having
a donor binder;
a cationic infrared absorbing dye;
a thermally activated crosslinking agent of the formula
wherein n is 1-50, R 1 is CH 2 or CH 2 OCH 2 at either an ortho- or para-position, R 2 is alkyl at the meta-position when R 1 is para or alkyl at the para-position when R 1 is ortho- and R 3 is independently hydrogen or butyl; and
a dispersible material; and
a receptor element.
25. The thermal imaging system of claim 24 wherein the transfer material further comprises a fluorocarbon additive.
26. The thermal imaging system of claim 25 wherein the fluorocarbon additive comprises a sulfonamido compound.
27. The thermal imaging system of claim 25 wherein the fluorocarbon additive comprises (C 8 F 17 )SO 2 NH(CH 2 CH 3 ).
28. The thermal imaging system of claim 25 wherein the fluorocarbon additive is present in an amount of from about 0.5 to about 5 wt-% based on the total weight of the transfer layer.
29. The thermal imaging system of claim 24 wherein the transfer layer further comprises coating aids, dispersing agents, optical brighteners, UV absorbers, fillers, surfactants, plasticizers or combinations thereof.
30. The thermal imaging system of claim 24 wherein the donor binder comprises a hydroxylic polymer.
31. The thermal imaging system of claim 24 wherein the donor binder is polyvinyl butyral.
32. The thermal imaging system of claim 24 wherein the donor binder is present in an amount of from about 20 to about 50 wt-% based upon the weight of the transfer layer.
33. The thermal imaging system of claim 24 wherein the cationic infrared absorbing dye is a bleachable dye.
34. The thermal imaging system of claim 24 wherein the cationic infrared absorbing dye is a tetraarylpolymethine dye, an amine cation radical dye, or mixtures thereof.
35. The thermal imaging system of claim 24 wherein the cationic infrared absorbing dye is a tetraarylpolymethine dye.
36. The thermal imaging system of claim 24 wherein the cationic infrared absorbing dye is present in an amount of from about 5 to about 20 wt-% based on total weight of the transfer layer.
37. The thermal imaging system of claim 24 wherein the thermally activated crosslinking agent is of the formula
wherein n is 1-50 and R 2 can be independently hydrogen or alkyl.
38. The thermal imaging system of claim 24 wherein the thermally activated crosslinking agent of the formula
wherein n is 1-50 and R 2 can be independently hydrogen or alkyl.
39. The thermal imaging system of claim 24 wherein the thermally activated crosslinking agent is present in an amount of from about 1 to about 10 wt-% based on the total weight of the transfer material.
40. The thermal imaging system of claim 24 wherein the dispersible material is a pigment, a crystalline nonsubliminable dye, a color enhancing additive, a texturizing material, or mixtures thereof.
41. The thermal imaging system of claim 24 wherein the dispersible material comprises a pigment.
42. The thermal imaging system of claim 24 wherein the dispersible material comprises a cystalline nonsubliminable dye.
43. The thermal imaging system of claim 24 wherein the dispersible material comprises metallic flakes.
44. The thermal imaging system of claim 24 wherein the dispersible material is present in an amount of from about 15 to about 50 wt-% based on the total weight of the transfer layer.
45. The thermal imaging system of claim 24 wherein the transfer material further comprises a crosslinking agent of the formula
wherein R 1 is hydrogen, alkyl, cycloalkyl or aryl, R 2 and R 3 are independently alkyl or aryl and R 4 is aryl.
46. The thermal imaging system of claim 24 wherein the donor element further comprises an intermediate transfer layer disposed between the substrate and the transfer layer having
an intermediate layer donor binder; and
a cationic infrared absorbing dye.
47. The thermal imaging system of claim 24 wherein the receptor element comprises a receptor binder.
48. The thermal imaging system of claim 24 wherein the receptor element comprises a bleaching agent.
49. The thermal imaging system of claim 24 wherein the receptor element comprises a substrate having a textured receiving layer surface comprising a plurality of protrusions projecting above the outer surface of the substrate by an average distance of from about 1 μm to about 8 μm.
50. A laser-induced thermal imaging system comprising:
a donor element comprising a donor substrate coated with a transfer layer having:
a donor binder;
a fluorocarbon additive;
a cationic infrared absorbing dye;
a thermally activated crosslinking agent of the formula:
wherein n is 0 to 50, R 1 is CH 2 or CH 2 OCH 2 at either an ortho- or para-position, R 2 is alkyl at the meta-position when R 1 is para or alkyl at the para-position when R 1 is ortho and R 3 is independently hydrogen or butyl; and
a dispersible material; and
a receptor element comprising a receptor substrate coated with a receptor material having:
a receptor binder;
a bleaching agent; and
particulate material.
51. A method of imaging comprising the steps of:
(a) assembling a donor element in contact with a receptor element wherein the donor element comprises a donor substrate coated with a transfer layer having:
a donor binder;
a cationic infrared absorbing dye;
a thermally activated crosslinking agent of the formula:
wherein n is 0 to 50, R 1 is CH 2 or CH 2 OCH 2 at either an ortho- or para-position, R 2 is alkyl at the meta-position when R 1 is para or alkyl at the para-position when R 1 is ortho and R 3 is independently hydrogen or butyl; and
a dispersible material
(b) exposing the assembly to laser radiation of a wavelength absorbed by the cationic infrared absorbing dye wherein the laser radiation is capable of being modulated in accordance with digitally stored image information, wherein the exposed portions of the donor element are transferred to the receptor element; and
(c) separating the donor element and the receptor element, wherein the image residing on the receptor element is revealed.
52. The method of imaging of claim 51 wherein the method further comprises the step of subjecting the receptor element and image residing on the receptor element to heat treatment.
53. The method of imaging of claim 51 wherein steps (a)-(c) form a cycle which is repeated, wherein a different donor element comprising a different dispersant is used for each cycle, but the same receptor element is used for each cycle.
54. The method of imaging of claim 51 wherein the image residing on the receptor after all the repetitions of steps (a)-(c) is transferred to another receptor as a final step.
55. A method of making a thermal imaging system comprising the steps of:
(a) dissolving a donor binder, a cationic infrared absorbing dye, a thermally activated crosslinking agent of the formula:
wherein n is 0 to 50, R 1 is CH 2 or CH 2 OCH 2 at either an ortho- or para-position, R 2 is alkyl at the meta-position when R 1 is para or alkyl at the para-position when R 1 is ortho and R 3 is independently hydrogen or butyl, and a dispersible material with an organic solvent to form a donor solution;
(b) coating the donor solution onto a donor substrate;
(c) drying the donor solution coating;
(d) dissolving a receptor binder and a bleaching agent with an organic solution;
(e) coating the receptor solution onto a receptor substrate; and
(f) drying the receptor solution coating.
56. The method of making a thermal imaging system of claim 55 wherein the donor solution further comprises a fluorocarbon additive.
57. The method of making a thermal imaging system of claim 55 wherein the donor solution further comprises optional additives.
58. The method of making a thermal imaging system of claim 55 wherein the donor solution further comprises an organic solvent.
59. The method of making a thermal imaging system of claim 58 wherein the organic solvent is methyl ethyl ketone, methyl isobutyl ketone, ethanol or mixtures thereof.