Preparation of solvent-resistant binder for an imageable element
View Patent ↗The present invention provides an imageable element including a lithographic substrate and an imageable layer disposed on the substrate. The imageable layer includes a radically polymerizable component, an initiator system capable of generating radicals sufficient to initiate a polymerization reaction upon exposure to imaging radiation, and a polymeric binder having a hydrophobic backbone and including both constitutional units having a pendant cyano group attached directly to the hydrophobic backbone, and constitutional units having a pendant group including a hydrophilic poly(alkylene oxide) segment. The invention also provides a method for preparing a suitable polymeric binder. The method comprises contacting a combination of co-monomers in a solvent mixture consisting essentially of a (C 1 –C 6 ) alkanol and water.
1. A method for preparing a copolymeric binder, comprising:
in a solvent mixture consisting essentially of:
at least about 50 percent of a (C 1 –C 6 ) alkanol or a mixture thereof, by weight, and
at least about 10 percent water, by weight;
contacting a combination of co-monomers in the presence of a polymerization initiator, the combination of co-monomers including:
a) at least 50 percent (meth)acrylonitrile, by weight,
b) poly(ethylene glycol) alkyl ether (meth)acrylate, and
c) styrene, to produce the copolymeric binder in the form of discrete particles and having a number average molecular weight in the range from about 10,000 Da to about 250,000 Da.
2. The method of claim 1 , wherein the solvent mixture consists essentially of:
about 50 to about 80 percent by weight of the alkanol or mixture of alkanols; and
about 20 to about 50 percent by weight water.
3. The method of claim 1 , wherein the solvent mixture consists essentially of:
about 50 percent by weight of the alkanol or mixture of alkanols; and
about 50 percent by weight water.
4. The method of claim 1 , wherein solvent mixture consists essentially of:
about 80 percent by weight of the alkanol or mixture of alkanols; and
about 20 percent by weight water.
5. The method of claim 1 , wherein the alkanol or mixture of alkanols consists of one or more (C 2 –C 4 ) alkanol.
6. The method of claim 1 , wherein the alkanol or mixture of alkanols includes n-propanol.
7. The method of claim 1 , wherein the alkanol is n-propanol.
8. The method of claim 1 , wherein the solvent mixture consists essentially of:
about 50 percent by weight n-propanol; and
about 50 percent by weight water.
9. The method of claim 1 , wherein the solvent mixture consists essentially of:
about 80 percent by weight n-propanol; and
about 20 percent by weight water.
10. The method of claim 1 , wherein the poly(ethylene glycol) alkyl ether (meth)acrylate co-monomer includes poly(ethylene glycol) methyl ether methacrylate.
11. The method of claim 10 , wherein the poly(ethylene glycol) methyl ether methacrylate has a molecular weight in the range from about 300 Da to about 10,000 Da.
12. The method of claim 10 , wherein the poly(ethylene glycol) methyl ether methacrylate has a molecular weight in the range from about 1000 Da to about 3000 Da.
13. The method of claim 1 , wherein the combination of co-monomers includes:
about 55 to about 90 percent (meth)acrylonitrile, by weight;
about 5 to about 15 percent poly(ethylene glycol) alkyl ether (meth)acrylate, by weight; and
about 5 to about 30 percent styrene, by weight.
14. The method of claim 1 , wherein the combination of co-monomers includes acrylonitrile, poly(ethylene glycol) methyl ether methacrylate, and styrene.
15. The method of claim 1 , wherein the combination of co-monomers includes:
about 55 to about 90 percent acrylonitrile, by weight;
about 5 to about 15 percent poly(ethylene glycol) methyl ether methacrylate, by weight; and
about 5 to about 30 percent styrene, by weight.
16. The method of claim 1 , wherein the combination of co-monomers consists essentially of acrylonitrile, poly(ethylene glycol) methyl ether methacrylate, and styrene.
17. The method of claim 1 , wherein the combination of co-monomers further includes an ethylenically unsaturated monomer including a trialkoxysilyl group.
18. The method of claim 17 , wherein the trialkoxysilyl group is a trimethoxysilyl group.
19. The method of claim 17 , wherein the ethylenically unsaturated monomer including a trialkoxysilyl group is 3-[trimethoxysilyl] propyl acrylate or 3-[trimethoxysilyl] propyl methacrylate.
20. The method of claim 1 , wherein the particles are characterized by an average diameter in the range from about 100 nm to about 700 nm.
21. The method of claim 1 , wherein the particles are characterized by an average diameter in the range from about 150 nm to about 250 nm.
22. A method for preparing an imageable element having an imageable layer on a lithographic substrate, comprising the steps of:
contacting a combination of co-monomers in the presence of a polymerization initiator, the combination of co-monomers including:
a) at least 50 percent (meth)acrylonitrile, by weight,
b) poly(ethylene glycol) alkyl ether (meth)acrylate, and
c) styrene; in a reaction solvent mixture consisting essentially of at least about 50 percent of a (C 1 –C 6 ) alkanol or a mixture thereof, by weight, and at least about 10 percent water, by weight, to produce a copolymeric binder in the form of discrete particles and having a number average molecular weight in the range from about 10,000 Da to about 250,000 Da;
preparing a coating composition comprising:
a radically polymerizable component,
an initiator system capable of generating radicals sufficient to initiate a polymerization reaction upon exposure to imaging radiation,
the copolymeric binder, and
a coating solvent;
contacting a lithographic substrate with the coating composition to produce a coating on the substrate; and
removing solvent from the coating to produce the imageable layer on the substrate.
23. The method of claim 22 , wherein the combination of co-monomers includes:
about 55 to about 90 percent acrylonitrile, by weight;
about 5 to about 15 percent poly(ethylene glycol) methyl ether methacrylate, by weight; and
about 5 to about 30 percent styrene, by weight.
24. The method of claim 22 , wherein the combination of co-monomers consists essentially of acrylonitrile, poly(ethylene glycol) methyl ether methacrylate, and styrene.
25. The method of claim 22 , wherein the solvent mixture consists essentially of:
about 50 to about 80 percent by weight of the alkanol or mixture of alkanols; and
about 20 to about 50 percent by weight water.
26. The method of claim 22 , wherein the reaction solvent mixture consists essentially of:
about 50 percent by weight of the alkanol or mixture of alkanols; and
about 50 percent by weight water.
27. The method of claim 22 , wherein the reaction solvent mixture consists essentially of:
about 80 percent by weight of the alkanol or mixture of alkanols; and
about 20 percent by weight water.
28. The method of claim 22 , wherein the alkanol or mixture of alkanols consists of one or more (C 2 –C 4 ) alkanol.
29. The method of claim 22 , wherein the alkanol is n-propanol.
30. The method of claim 22 , wherein the reaction solvent mixture consists essentially of:
about 50 percent by weight n-propanol; and
about 50 percent by weight water.
31. The method of claim 22 , wherein the reaction solvent mixture consists essentially of:
about 80 percent by weight n-propanol; and
about 20 percent by weight water.
32. The method of claim 22 , wherein the coating solvent consists essentially of the alkanol or mixture of alkanols, and water.
33. The method of claim 22 , wherein the coating solvent consists essentially of the alkanol or mixture of alkanols, water, and a (C 3 –C 4 ) ketone or a mixture thereof.
34. The method of claim 22 , wherein the coating solvent consists essentially of n-propanol, water, and 2-butanone.
35. The method of claim 22 , wherein the coating composition further comprises a second binder having crosslinkable ethylenically unsaturated sites.
36. The method of claim 22 , wherein the lithographic substrate is a sulfuric acid-anodized aluminum sheet.
37. The method of claim 22 , wherein the lithographic substrate is a phosphoric acid-anodized aluminum sheet.
38. The method of claim 22 , wherein the imageable element comprises an interlayer between the lithographic substrate and the imageable layer.
39. The method of claim 22 , wherein the particles are characterized by an average diameter in the range from about 100 nm to about 700 nm.
40. The method of claim 22 , wherein the particles are characterized by an average diameter in the range from about 150 nm to about 250 nm.
41. The method of claim 22 , wherein the imageable layer has a dry coating weight of about 0.5 g/m 2 to about 1.5 g/m 2 .
42. The method of claim 22 , wherein the imaging radiation is infrared radiation.
43. An imageable element made according to the method of claim 22 .