Multilayer imageable elements
View Patent ↗Multilayer, positive working, thermally imageable elements are disclosed. The elements produce bakeable lithographic printing plates that are resistant to press chemistries. The elements have a substrate, an underlayer, and a top layer. The underlayer comprises a resin or resins having activated methylol and/or activated alkylated methylol groups, such as a resole resin, and a polymeric material that comprises, in polymerized form, (a) methacrylic acid; (b) N-phenylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, or a mixture thereof; and (c) one or more monomers of the structure: in which: R 1 is H or methyl; X is —(CH 2 ) n —, where n is an integer from 2 to 12; —(CH 2 —CH 2 —O) p —CH 2 —CH 2 —, where p is an integer from 1 to 3; or —Si(R′)(R″)— where R′ and R″ are each independently methyl or ethyl; and m is 1, 2, or 3.
1. An imageable element comprising:
a substrate;
an underlayer over the substrate; and
a top layer over the underlayer;
in which:
the element comprises a photothermal conversion material;
the top layer is substantially free of the photothermal conversion material;
the top layer is ink receptive;
before thermal imaging, the top layer is not removable by an alkaline developer;
after thermal imaging to form imaged regions in the top layer, the imaged regions are removable by the alkaline developer;
the underlayer is removable by the alkaline developer, and
the underlayer comprises a polymeric material that comprises, in polymerized form:
about 5 mol % to about 40 mol % of methacrylic acid;
about 20 mol % to about 75 mol % of N-phenylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, or a mixture thereof; and
about 3 mol % to about 50 mol % of one or more monomers of the structure:
in which:
R 1 is H or methyl;
X is —(CH 2 ) n —, where n is an integer from 2 to 12;
—(CH 2 —CH 2 —O) p —CH 2 —CH 2 —, where p is an integer from 1 to 3; or —Si(R′)(R″)— where R′ and R″ are each independently methyl or ethyl; and
m is 1, 2, or 3.
2. The element of claim 1 in which R 1 is CH 3 , m is 1, X is —(CH 2 ) n —, and n is 2.
3. The element of claim 1 in which the underlayer additionally comprises a resin having activated methylol or activated alkylated methylol groups.
4. The element of claim 3 in which the underlayer comprises about 7 wt % to about 15 wt % of the resin having activated methylol or activated alkylated methylol groups and about 15 wt % to 93 wt % the polymeric material.
5. The element of claim 4 in which the resin having activated methylol or activated alkylated methylol groups is resole resin.
6. The element of claim 5 in which the polymeric material additionally comprises, in polymerized form, about 5 mol % to about 50 mol % of acrylamide, methacrylamide, or a mixture thereof.
7. The element of claim 5 in which the polymeric material additionally comprises, in polymerized form, about 10 mol % to about 70 mol % of acrylonitrile, methacrylonitrile, or a mixture thereof.
8. The element of claim 5 in which the underlayer comprises about 0.5 wt % to about 20 wt % of a photothermal conversion material, about 7 wt % to about 15 wt % of the resole resin, and about 60 wt % to 90 wt % of the polymeric material.
9. The element of claim 8 in which the polymeric material comprises, in polymerized form, about 10 mol % to about 30 mol % of methacrylic acid; about 35 mol % to about 60 mol % of N-phenylmaleimide; and about 10 mol % to about 40 mol % of compound (a).
10. The element of claim 9 in which the polymeric material additionally comprises, in polymerized form, about 15 mol % to about 40 mol % of methacrylamide.
11. The element of claim 10 in which the underlayer comprises about 5 wt % to about 20 wt % of the photothermal conversion material, about 8 wt % to about 12 wt % of the resole resin, and about 65 wt % to about 80 wt % of the polymeric material.
12. The element of claim 3 in which:
the underlayer additionally comprises a first added copolymer, and
the first added copolymer comprises, in polymerized form, about 1 wt % to about 30 wt % of N-phenylmaleimide; about 1 wt % to about 30 wt % of methacrylamide; about 20 wt % to about 75 wt % of acrylonitrile; and about 20 wt % to about 75 wt % of one or more monomers of the structure:
CH 2 ═C(R 3 )—CO 2 —CH 2 —CH 2 NH—CO—NH- p —C 6 H 4 —R 2 ,
in which R 2 is OH, COOH, or SO 2 NH2; and R 3 is H or methyl.
13. The element of claim 12 in which the first added copolymer additionally comprises, in polymerized form, about 1 wt % to about 30 wt % of one or more monomers of the structure:
CH 2 ═C(R 5 )—CO—NH- p —C 6 H 4 —R 4
in which R 4 is OH, COOH, or SO 2 NH 2 ; and R 5 is H or methyl.
14. The element of claim 13 in which the underlayer comprises about 0.5 wt % to about 20 wt %, of the photothermal conversion material, about 7 wt % to about 15 wt % of the resin having activated methylol or activated alkylated methylol, and about 40 wt % to about 80 wt % of the polymeric material, and about 5 wt % to about 25 wt % of the first added copolymer.
15. The element of claim 14 in which the polymeric material additionally comprises, in polymerized form, about 5 mol % to about 50 mol % of methacrylamide.
16. The element of claim 14 in which R 1 is CH 3 , m is 1, X is —(CH 2 ) n —, and n is 2.
17. The element of claim 16 in which the underlayer comprises about 5 wt % to about 20 wt % of the photothermal conversion material, about 8 wt % to about 12 wt % of the resin having activated methylol or activated alkylated methylol groups, about 50 wt % to about 70 wt % of the polymeric material, and about 10 wt % to about 20 wt %, of the first added copolymer; and
the resin having activated methylol or activated alkylated methylol is a resole resin.
18. The element of claim 17 in which the first added copolymer additionally comprises, in polymerized form, 1 wt % to 30 wt % of one or more monomers of the structure:
CH 2 ═C(R 5 )—CO—N H- p —C 6 H 4 —R 4
in which R 4 is OH, COOH, or SO 2 NH 2 ; and R 5 is H or methyl.
19. The element of claim 18 in which the top layer comprises a novolac resin and a dissolution inhibitor.
20. The element of claim 12 in which:
the underlayer additionally comprises a second added copolymer, and
the second added copolymer comprises, in polymerized form, about 25 mol % to about 75 mol % of N-phenylmaleimide; about 10 mol % to about 50 mol % of methacrylamide; and about 5 mol % to about 30 mol % of methacrylic acid.
21. The element of claim 20 in which the polymeric material additionally comprises, in polymerized form, about 5 mol % to about 50 mol % of methacrylamide.
22. The element of claim 20 in which the underlayer comprises about 0.5 wt % to about 20 wt % of the photothermal conversion material, about 7 wt % to about 15 wt % of the resin having activated methylol or activated alkylated methylol groups, about 15 wt % to about 45 wt % of the polymeric material, about 5 wt % to 25 wt % of the first added copolymer, and about 15 wt % to about 45 wt % of the second added copolymer.
23. The element of claim 22 in which R 1 is CH 3 , m is 1, X is —(CH 2 ) n —, and n is 2.
24. The element of claim 23 in which the polymeric material comprises, in polymerized form, about 10 mol % to about 30 mol % of methacrylic acid; about 35 mol % to about 60 mol % of N-phenylmaleimide; and about 10 mol % to about 40 mol % of compound (a).
25. The element of claim 24 in which the polymeric material additionally comprises, in polymerized form, about 15 mol % to about 40 mol % of methacrylamide.
26. The element of claim 25 in which the first added copolymer additionally comprises about 1 wt % to about 30 wt % of one or more monomers of the structure:
CH 2 C(R 5 )CO—NH- p —C 6 H 4 —R 4
in which R 4 is OH, COOH, or SO 2 NH 2 ; and R 5 is H or methyl.
27. The element of claim 25 in which:
the underlayer comprises about 5 wt % to about 20 wt % of the photothermal conversion material, about 8 wt % to about 12 wt % of the resin having activated methylol or activated alkylated methylol groups, about 20 wt % to 40 wt % of the polymeric material, about 10 wt % to 20 wt % of the first added copolymer, and about 20 wt % to 40 wt % of the second added copolymer; and
the resin having activated methylol or activated alkylated methylol groups is a resole resin.
28. The element of claim 26 in which the top layer comprises a novolac resin and a dissolution inhibitor.
29. The element of claim 5 additionally comprising an absorber layer between the underlayer and the top layer, the absorber layer consisting essentially of the photothermal conversion material.
30. The element of claim 29 in which the underlayer comprises about 7 wt % to about 15 wt % of the resole resin, and about 15 wt % to 93 wt % of the polymeric material.
31. The element of claim 28 in which R 1 is CH 3 , m is 1, X is —(CH 2 ) n —, and n is 2.
32. A method for forming an image, the method comprising the steps of:
a) thermally imaging a multi-layer imageable element and forming an imaged imageable element comprising imaged and complementary unimaged regions;
in which:
the multi-layer imageable element comprises:
a substrate;
an underlayer over the substrate; and
a top layer over the underlayer;
before thermal imaging, the top layer is not removable by an alkaline developer;
after thermal imaging to form imaged regions in the top layer, the imaged regions are removable by the alkaline developer;
the underlayer is removable by the alkaline developer, and
the underlayer comprises a polymeric material that comprises, in polymerized form:
about 5 mol % to about 40 mol % of methacrylic acid;
about 20 mol % to about 75 mol % of N-phenylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, or a mixture thereof; and
about 3 mol % to about 50 mol % of one or more monomers of the structure:
in which:
R 1 is H or methyl;
X is —(CH 2 ) n —, where n is an integer from 2 to 12;
—(CH 2 —CH 2 —O) p —CH 2 —CH 2 —, where p is an integer from 1 to 3; or —Si(R″)(R″)— where R′ and R″ are each independently methyl or ethyl;-and
m is 1, 2, or 3;
the element comprises a photothermal conversion material;
the top layer is substantially free of the photothermal conversion material;
the top layer is ink receptive;
b) developing the imaged imageable element with the developer and removing the imaged regions without substantially affecting the unimaged regions.
33. The method of claim 32 additionally comprising the step of baking the imaged imageable element after step b).
34. The method of claim 33 in which the underlayer additionally comprises all resin having activated methylol or activated alkylated methylol groups.
35. The method of claim 34 in which the underlayer comprises about 7 wt % to about 15 wt % of the resin having activated methylol or activated alkylated methylol groups, and about 15 wt % to 93 wt % of the polymeric material.
36. The method of claim 35 in which the resin having activated methylol or activated alkylated methylol groups is resole resin.
37. The method of claim 36 in which R 1 is CH 3 , m is 1, X is —(CH 2 ) n —, and n is 2.
38. The method of claim 37 in which the polymeric material additionally comprises, in polymerized form, about 5 mol % to about 50 mol % of methacrylamide.
39. An image formed by the method of claim 33 .