Water-developable infrared-sensitive printing plate
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 constitutional units having a pendant group including a hydrophilic poly(alkylene oxide) segment. The imageable element can be developed using an aqueous developer solution. Alternatively, the imageable element can be developed on-press by contact with ink and/or fountain solution.
1. An imageable element comprising:
a lithographic substrate; and
an imageable layer disposed on the substrate at a coating weight of less than 1.5 g/m 2 and including
a) at least 35 wt.-%, based on the solids content of the imageable layer, of a radically polymerizable monomer, oligomer, or combination thereof;
b) an initiator system capable of generating radicals sufficient to initiate a polymerization reaction upon exposure to imaging radiation; and
c) a polymeric binder having a hydrophobic backbone and including constitutional units having a pendant group including a hydrophilic poly(alkylene oxide) segment; wherein the binder is present in the imageable layer in the form of discrete particles.
2. The imageable element of claim 1 , wherein the coating weight is in the range from about 0.6 to 1.2 g/m 2 .
3. The imageable element of claim 1 , wherein the imageable layer includes between 35 wt.-% and 60 wt.-%, based on the solids content of the imageable layer, of the radically polymerizable monomer, oligomer, or combination thereof.
4. The imageable element of claim 1 , wherein the initiator system is capable of generating radicals sufficient to initiate a polymerization reaction upon exposure to infrared radiation in the range from about 700 nm to 1200 nm.
5. The imageable element of claim 1 , wherein the particles are characterized by an average diameter in the range from about 100 nm to 700 nm.
6. The imageable element of claim 1 , wherein the particles are characterized by an average diameter in the range from about 150 nm to 250 nm.
7. The imageable element of claim 1 , wherein the imageable layer further includes a contrast dye.
8. The imageable element of claim 7 , wherein the contrast dye is a triarylmethane dye, diphenylnaphthylmethane dye, quinoline dye, styryl dye, xanthene dye, thiazine dye, or a combination thereof.
9. The imageable element of claim 7 , wherein the contrast dye is crystal violet, methyl violet, ethyl violet, Victoria blue, malachite green, brilliant green, a dye of the following structure:
or a combination thereof.
10. A method for making a printing plate, comprising the steps of:
providing an imageable element comprising:
a lithographic substrate; and
an imageable layer disposed on the substrate at a coating weight of less than 1.5 g/m 2 and including
a) at least 35 wt.-%, based on the solids content of the imageable layer, of a radically polymerizable monomer, oligomer, or combination thereof;
b) an initiator system capable of generating radicals sufficient to initiate a polymerization reaction upon exposure to imaging radiation; and
c) a polymeric binder having a hydrophobic backbone and including constitutional units having a pendant group including a hydrophilic poly(alkylene oxide) segment; wherein the binder is present in the imageable layer in the form of discrete particles;
imagewise exposing the imageable element to imaging radiation; and
developing the exposed element by contacting the element with a suitable developer solution, to yield the printing plate.
11. The method of claim 10 , wherein the coating weight is in the range from about 0.6 to 1.2 g/m 2 .
12. The method of claim 10 , wherein the imageable layer further includes a contrast dye.
13. The method of claim 12 , wherein the contrast dye is a triarylmethane dye, diphenylnaphthylmethane dye, quinoline dye, styryl dye, xanthene dye, thiazine dye, or a combination thereof.
14. The method of claim 12 , wherein the contrast dye is crystal violet, methyl violet, ethyl violet, Victoria blue, malachite green, brilliant green, a dye of the following structure:
or a combination thereof.
15. The method of claim 10 , wherein the developer solution is an aqueous-based solution.
16. The method of claim 10 , wherein the developer solution consists essentially of water.
17. The method of claim 10 , wherein the developer solution consists essentially of water and an alcohol or alcohol-replacement additive.
18. The method of claim 10 , wherein the developer solution comprises a surfactant.
19. The method of claim 10 , wherein the step of developing includes heating the developer solution to a temperature greater than about 80° F.
20. The method of claim 10 , wherein the step of developing is done on-press, and the developer solution comprises ink, fountain solution, or a combination thereof.