Mask element precursor and relief image-forming system
An imageable material can be used to form a mask element that in turn is useful for providing relief images such as in flexographic printing plates. The imageable material has, in order: (a) a transparent polymeric carrier sheet; (b) a non-ablatable light-to-heat converting having an average dry thickness of 1-5 μm and comprising: (i) an infrared radiation absorbing material at 0.1-5 weight %; (ii) a thermally crosslinked organic polymeric binder material; and (iii) non-thermally ablatable particles having an average particle size of 0.1-20 μm in an amount of 0.2-10 weight %; and (c) a non-silver halide thermally-ablatable imaging layer (IL) disposed on the LTHC layer, the IL comprising a second infrared radiation absorbing material and a UV-light absorbing material dispersed within one or more thermally-ablatable polymeric binder materials.
1. An imageable material useful for making a mask element, the imageable material consisting essentially of, in order:
(a) a transparent polymeric carrier sheet;
(b) a non-ablatable light-to-heat converting (LTHC) layer disposed directly on the transparent polymeric carrier sheet, the LTHC layer having an average dry thickness of at least 1 μm and up to and including 5 μm, and comprising:
(i) a first infrared radiation absorbing material in an amount of at least 0.1 weight % and up to and including 5 weight %;
(ii) a thermally crosslinked organic polymeric binder material; and
(iii) non-thermally ablatable particles having an average particle size of at least 0.1 μm and up to and including 20 μm and that are present in an amount of at least 0.2 weight % and up to and including 10 weight %, all weight percentages being based on the total dry weight of the LTHC layer;
(c) a non-silver halide thermally-ablatable imaging layer (IL) disposed directly on the LTHC layer, the IL comprising a second infrared radiation absorbing material and a UV-light absorbing material dispersed within one or more thermally-ablatable polymeric binder materials; and
the imageable material optionally further comprising (d) a transparent polymeric overcoat layer disposed directly on the IL.
2. The imageable material of claim 1 , wherein the one or more thermally-ablatable polymeric binder materials in the IL are nitrocellulose, a poly(cyanoacrylate), or a combination thereof.
3. The imageable material of claim 1 , wherein the one or more thermally-ablatable polymeric binder materials are present in the IL in an amount of at least 25 weight % and up to and including 75 weight %, based on the total dry weight of the IL.
4. The imageable material of claim 1 , wherein the second infrared radiation absorbing material is present in the IL in an amount of at least 3 weight % and up to and including 20 weight %, based on the total dry weight of the IL.
5. The imageable material of claim 1 , wherein each of the first and second infrared radiation absorbing materials independently have an absorbance maximum in the electromagnetic radiation wavelength range of at least 700 nm and up to and including 1200 nm.
6. The imageable material of claim 1 , wherein the UV-light absorbing material is present in the IL in an amount of at least 10 weight % and up to and including 40 weight %, based on the total dry weight of the IL.
7. The imageable material of claim 1 , wherein the IL further comprises one or more fluorocarbon additives or one or more non-thermally ablatable colorants.
8. The imageable material of claim 1 , wherein the transparent polymeric carrier sheet is composed of one or more polyesters, polyethylene-polypropylene copolymers, polybutadienes, polycarbonates, polyacrylates, vinyl chloride polymers, hydrolyzed or non-hydrolyzed cellulose acetates, or a combination of two or more of these materials.
9. The imageable material of claim 1 , wherein the non-thermally ablatable particles in the LTHC layer are composed of particles of silica, titanium dioxide, zinc oxide, or a combination of two or more types of such particles.
10. The imageable material of claim 1 , wherein the non-thermally ablatable particles are present in the LTHC layer in an amount of at least 1 weight % and up to and including 7 weight %, based on the total dry weight of the LTHC layer.
11. The imageable material of claim 1 , wherein the thermally crosslinked organic polymeric binder material in the LTHC layer is composed of crosslinked nitrocellulose, a crosslinked polyester, or a combination of two or more of such crosslinked organic polymeric materials.
12. The imageable material of claim 1 , wherein the thermally crosslinked organic polymeric binder material is present in the LTHC layer in an amount of at least 40 weight % and up to and including 90 weight %, based on the total dry weight of the LTHC layer.
13. The imageable material of claim 1 , wherein the first and second infrared radiation absorbing materials are the same materials.
14. The imageable material of claim 1 , wherein the transparent polymeric carrier sheet has an average dry thickness of at least 25 μm and up to and including 250 μm.
15. The imageable material of claim 1 , wherein the LTHC layer has an average dry thickness of at least 1 μm and up to and including 3 μm.
16. The imageable material of claim 1 , wherein the IL has an average dry thickness of at least 0.5 μm and up to and including 5 μm.
17. The imageable material of claim 1 , wherein the transparent polymeric overcoat layer is present and has an average dry thickness of at least 0.05 μm and up to and including 1 μm.
18. The imageable material of claim 1 , wherein the non-thermally ablatable particles have an average particle size of at least 5 μm and up to and including 15 μm.
19. A relief image-forming system, comprising:
(1) an imageable material;
(2) a relief-forming precursor comprising a UV-sensitive layer; and
(3) a developer in which the UV-sensitive layer is soluble or dispersible, the imageable material consisting essentially of, in order:
(a) a transparent polymeric carrier sheet;
(b) a non-ablatable light-to-heat converting (LTHC) layer disposed directly on the transparent polymeric carrier sheet, the LTHC layer having an average dry thickness of at least 1 μm and up to and including 5 μm, and comprising:
(i) a first infrared radiation absorbing material in an amount of at least 0.1 weight % and up to and including 5 weight %;
(ii) a thermally crosslinked organic polymeric binder material; and
(iii) non-thermally ablatable particles having an average particle size of at least 0.1 μm and up to and including 20 μm and that are present in an amount of at least 0.2 weight % and up to and including 10 weight %, all weight percentages being based on the total dry weight of the LTHC layer;
(c) a non-silver halide thermally-ablatable imaging layer (IL) disposed directly on the LTHC layer, the IL comprising a second infrared radiation absorbing material and a UV-light absorbing material dispersed within one or more thermally-ablatable polymeric binder materials; and
the imageable material optionally further comprising (d) a transparent polymeric overcoat layer disposed directly on the IL.