Use of cover sheet and interposed flexible film with block copolymer composition
AssigneeE. I. Du Pont de Nemours and Company
InventorsGwendyline Y. Y. T. Chen, James F. Brennan
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Abstract
Photosensitive elements comprising a layer of a solvent-soluble, thermoplastic, elastomeric, block copolymer, a nongaseous ethylenically unsaturated compound, and an addition polymerization initiator activatable by actinic light interposed between a support and cover sheet, a flexible polymeric film, e.g., polyamide, being interposed between the cover sheet and the surface of the layer. The elements are useful in preparing printing plates, particularly flexographic printing plates, and other relief images.
Claims8
A photosensitive element which comprises a sheet support;
- a layer of a photosensitive, elastomeric composition coated on said support having a thickness of from about 0.0005 to about 0.250 inch, said composition comprising
- (1) at least 30% by weight of at least one solvent-soluble, thermoplastic, elastomeric block copolymer containing at least two thermoplastic, nonelastomeric polymer blocks having a glass transition temperature above 25.degree. C. and an average molecular weight of 2000-100,000, and between said thermoplastic, nonelastomeric polymer blocks an elastomeric polymer block having a glass transition temperature below 10.degree. C. and an average molecular weight of about 25,000 to 1,000,000.
- (2) at least 1% by weight of an addition-polymerizable ethylenically unsaturated compound containing at least one terminal ethylenical group, and
- (3) a polymerization-effective amount of polymerization initiator activatable by actinic radiation;
- a flexible cover sheet;
- and a flexible, polymeric film interposed between said cover sheet and the surface of said layer.
A photosensitive element which comprises a sheet support;
- a layer of a photosensitive, elastomeric composition coated on said support having a thickness of from about 0.0005 to about 0.250 inch, said composition comprising
- (1) at least 30% by weight of at least one solvent-soluble, thermoplastic, elastomeric block copolymer containing at least two thermoplastic, nonelastomeric polymer blocks having a glass transition temperature above 25.degree. C. and an average molecular weight of 2000-100,000, and between said thermoplastic, nonelastomeric polymer blocks an elastomeric polymer block having a glass transition temperature below 10.degree. C. and an average molecular weight of about 25,000 to 1,000,000.
- (2) at least 1% by weight of an addition-polymerizable ethylenically unsaturated compound containing two terminal ethylenic groups, and
- (3) a polymerization-effective amount of polymerization initiator activatable by actinic radiation;
- a flexible cover sheet;
- and a flexible, polymeric film interposed between said cover sheet and the surface of said layer.
Dependencies are inferred from the claim text.