Preparation of gravure and intaglio printing elements using direct thermally imageable media
View Patent ↗A gravure printing element is fabricated using a negative-working thermally-imageable coating that is exposed using commercially available diode lasers, the coating being insensitive to ultraviolet light, daylight or visible light, and developable using aqueous media. A gravure etch mask is formed on a printing precursor by applying a coating of thermally-imageable material, curing the coating, imagewise illuminating the cured coating with a laser and removing with a developer the areas of the coating that were not illuminated. The masked precursor is then chemically etched to produce a gravure printing element.
1. A method for forming a gravure etch mask on a gravure printing precursor comprising the steps of:
(a) applying a coating of thermally-imageable material to a gravure printing precursor;
(b) curing said coating of thermally-imageable material;
(c) imagewise illuminating said cured coating of thermally-imageable material with a laser; and
(d) removing with a developer those areas of said coating of thermally-imageable material that have not been illuminated, thereby revealing areas of said gravure printing precursor.
2. A method according to claim 1 further comprising the step of chemically etching said gravure printing precursor in the areas of said gravure printing precursor revealed by said step of removing, to produce a gravure printing element.
3. A method according to claim 1 wherein step (a) is done by spraying said thermally-imageable material.
4. A method according to claim 1 wherein step (a) is done by rolling said thermally-imageable material.
5. A method according to claim 1 wherein said coating of thermally-imageable material is applied to a thickness of 0.5-15 microns.
6. A method according to claim 1 wherein said coating of thermally-imageable material is applied to a thickness of 0.7-10 microns.
7. A method according to claim 1 wherein step (b) is done by drying using heat.
8. A method accordingly to claim 1 wherein step (b) is done by applying ultraviolet or infrared radiation.
9. A method according to claim 1 wherein said laser emits light having a wavelength greater than 700 nm.
10. A method according to claim 1 wherein said laser emits light having a wavelength between 700-1100 nm.
11. A method according to claim 1 wherein said developer is an aqueous medium.
12. A method according to claim 1 wherein said thermally-imageable material comprises: (a) hydrophobic polymer particles; and (b) a material for converting light into heat.
13. A method according to claim 12 wherein said thermally-imageable material further comprises an organic base.
14. A method according to claim 13 wherein said organic base comprises piperazine, 2-methylpiperazine and 4-dimenthylaminobenzaldehyde.
15. A method according to claim 12 wherein said thermally-imageable material further comprises a metal complex.
16. A method according to claim 15 wherein said metal-complex comprises zinc acetate, copper (II) phthalocyaninetetrasulphonic acid, tetra sodium salt, aluminum acetylacetonate, cobalt acetylacetonate, and zinc acetylacetonate.
17. A method according to claim 12 wherein said thermally-imageable material further comprises an inorganic salt.
18. A method according to claim 17 wherein said inorganic salt comprises sodium acetate, potassium carbonate, lithium acetate or sodium metasilicate.
19. A method according to claim 12 wherein said thermally-imageable material further comprises an organic acid.
20. A method according to claim 19 wherein said organic acid comprises malonic acid, D, L lactic acid or citric acid.