Slip film compositions containing layered silicates
View Patent ↗The present invention relates to an improved slip film composition for use in manufacturing flexographic printing plates. The improved slip film composition of the invention comprises one or more solvents, one or more polymeric binders, a layered silicate, and optionally, a surfactant. The use of the layered silicate as a filler in the slip film composition produces an slip film composition with improved release properties and improved imaging. The slip film of the invention can be used with flexographic printing plates that are solvent developed or thermally developed.
1. A photosensitive printing plate comprising:
a) a support layer;
b) one or more layers of a photocurable material deposited on the support layer;
c) a slip film layer positioned on the one or more layers of photocurable material, the slip film layer comprising:
(i) one or more polymeric binders;
(ii) a layered silicate, wherein the layered silicate is selected from the group consisting of phyllosilicates, micaceous minerals, mixed layered illite/smectite minerals, and combinations of the foregoing; and
(iii) optionally, a surfactant; and
d) optionally, a removable coversheet.
2. The photosensitive printing plate according to claim 1 , wherein the one or more polymeric binders of the slip film layer are selected from the group consisting of polyacetals, polyacrylics, polyamides, polyimides, polybutylenes, polycarbonates, polyesters, polyethylenes, cellulosic polymers, polyphenylene ethers, polyethylene oxides, and combinations of the foregoing.
3. The photosensitive printing plate according to claim 2 , wherein the one or more polymeric binders of the slip film layer are selected from the group consisting of polyamides, cellulosic polymers, and combinations of the foregoing.
4. The photosensitive printing plate according to claim 2 , wherein the concentration of the one or more polymeric binders in the slip film layer is about 90% to about 97% by weight based on the total weight of the dry constituents.
5. The photosensitive printing plate according to claim 1 , wherein the slip film layer also comprises a U.V. absorbing material.
6. The photosensitive printing plate according to claim 1 , wherein the layered silicate of the slip film layer is a phyllosilicate and is selected from the group consisting of montmorillonite, bentonite, nontronite, biedellite, volkonskonite, hectorite, saponite, sauconite, sobockite, stevensite, svinfordite, vermiculite, and combinations of the foregoing.
7. The photosensitive printing plate according to claim 6 , wherein the layered silicate of the slip film layer is a natural montmorillonite or a montmorillonite containing an organic modifier.
8. The photosensitive printing plate according to claim 6 , wherein the concentration of the layered silicate in the slip film composition is about 1% to about 10% by weight based on the total weight of the dry constituents, not including one or more solvents.
9. The photosensitive printing plate according to claim 8 , wherein the concentration of the layered silicate in the slip film composition is about 2% to about 8% by weight based on the total weight of the dry constituents, not including one or more solvents.
10. The photosensitive printing plate according to claim 1 , wherein the surfactant is present in the slip film composition and comprises an ethoxylated nonyl phenol surfactant.
11. The photosensitive printing plate according to claim 10 , wherein the surfactant is present in the slip film composition at a concentration of about 0.5% to about 1.0% by weight based on the total weight of the dry constituents, not including one or more solvents.