Abstract: There is hereby provided a photosensitive resin composition suitable for a relief printing plate having an excellent resistance to a water based ink, whereby water or a water like solvent can be employed as a developing solution, which comprises;(i) a polymer (A) having a molecular weight of 5,000 to 500,000 which contains an amino group and a polymerizable double bond moiety,(ii) a monomer (B) having an .alpha.,.beta.-ethylenically unsaturated bond and a free acid group which can quaternize the nitrogen atom of the polymer (A),(iii) a photopolymerizable unsaturated compound (C), and(iv) a photopolymerization initiator (D).

Abstract: A water developable, photopolymerizable composition and printing plates prepared from such composition are disclosed. The photopolymerizable composition includes at least one water soluble polymer, such as polyvinyl alcohol or partially saponified polyvinyl acetate, at least one photopolymerization initiator, and the condensation reaction product of N-methylol acrylamide, N-methylol methacrylamide, N-alkyloxymethyl acrylamide or N-alkyloxymethyl methacrylamide with a melamine derivative of the following formula: ##STR1## wherein, R.sub.1 is CH.sub.2 OR, R.sub.2 is H or CH.sub.2 OR, and R is C.sub.1 -C.sub.4 alkyl. A thermal polymerization inhibitor may also be included in the composition.Plates prepared from the composition demonstrate improved hardness and water resistance, compared to previously known photopolymerizable compositions, and also achieve excellent image quality.

Abstract: A novel photosensitive film structure comprises a generally continuous minor phase material and a generally discontinuous major phase material. The minor phase includes a photosensitive compound whose solubility relative to a selected solvent changes upon exposure to electrromagnetic radiation, while the major phase is not photosensitive nor soluble in the solvent. The two phases are uniformly interdispersed throughout the film structure. Imagewise exposure to electromagnetic radiation renders the film structure selectively permeable to the selected solvent, and, after development, the film structure exhibits the chemical and physical properties of the major phase material. The film structure finds varied application in the manufacture of graphic arts articles such as lithographi printing plates and photoresists.

Abstract: Bilayer photosensitive imaging articles comprising a substrate coated with an image layer and a resist layer are disclosed. The substrate may be transparent, translucent or opaque to give imaging articles useful in different applications. The image layer which should be from about 0.3-3.0 microns in thickness includes an organic film-forming vehicle from the group of copolymers of the formula: ##STR1## where P is styrene, ethylene or methyl vinyl ether; m is 1-3; n is 1,10; X is OH, OHN.sub.2, ONH.sub.4, OR, ONH.sub.3 R, ONH.sub.2 R.sub.2, ONHR.sub.3, ONH.sub.3 RNH.sub.2, ONa, OK, OLi; R is an alkyl group in the range C.sub.1 -C.sub.10 optionally including a functional group such as ketone, alcohol, esther, ether alcohol or aryl; m=1-3, n=1-10; and the molecular weight is between 1,000-150,000. The image layer may also include a coloring medium. The resist layer, which should be from about 0.5 to about 2.

Abstract: An apparatus and method in which a coating is wetted with a solvent to initiate dissolution of soluble coating portions and the hydraulic pressure of the solvent at the surface of the coating is repeatedly increased and decreased to assist in the dissolution of the soluble coating portions. A brush with an array of bristles reciprocating in a path perpendicular to the coating may be utilized to produce the increasing and decreasing hydraulic pressure. Also, the coating may be immersed in the solvent to wet it and to initiate dissolution of the soluble coating portions.

Abstract: A desensitizing solution and process for using the solution are disclosed to desensitize a diazo photosensitive printing plate after development. The solution comprises a water soluble desensitizing agent capable of reacting with any residual photosensitive diazo on the developed plate to render the diazo incapable of forming an oleophilic substance and a filming agent selected from water soluble aliphatic polyols have less than eight carbon units, the acid derived monoesters of these polyols, and the alkali metal salts of the monoesters.

Abstract: A shallow relief non-bottoming printing plate is disclosed having a polymerized layer of less than about 0.020 inch and which includes a plurality of dispersed particles sufficient to create small protuberances in non-image or background areas to prevent bottoming. Photopolymerizable elements, as well as processing techniques, are also disclosed for making such printing plates.

Abstract: A photopolymerizable composition and photosensitive elements produced therefrom are disclosed. The photopolymerizable composition includes: (a) a monomer component, (b) a polymer component, (c) a photopolymerization initiator, and (d) an activator.The monomer component contains at least one water soluble, monofunctional unsaturated ethylenic monomer or the combination of such a monomer and at least one polyfunctional unsaturated ethylenic monomer.The polymer component includes a partially saponified water soluble, polyvinyl acetate polymer compatible with the monomer components. The polyvinyl acetate polymer contains both acetyl and hydroxyl groups and has a polymerization degree of from 300-2000. The degree of saponification of the polymer is desirably in the range of 65 to 99 percent.

Abstract: A photopolymerizable composition and photosensitive elements produced therefrom are disclosed. The photopolymerizable composition includes: (a) a monomer component, (b) a polymer component, (c) a photopolymerization initiator, and (d) an activator.The monomer component contains at least one water soluble, monofunctional unsaturated ethylenic monomer or the combination of such a monomer and at least one polyfunctional unsaturated ethylenic monomer.The polymer component includes a partially saponified water soluble, polyvinyl acetate polymer compatible with the monomer components. The polyvinyl acetate polymer contains both acetyl and hydroxyl groups and has a polymerization degree of from 300-2000. The degree of saponification of the polymer is desirably in the range of 65 to 99 percent.

Abstract: Letterpress and offset photopolymer printing plates are disclosed having relatively thin water developable photopolymer layers, which, after being developed, have ink-repulsive, non-image areas. Adhesive layers are provided in the disclosed printing plates that are interposed between an ink-repulsive coating contained in the printing plate substrate and the water-developable photopolymer, and provide a balance between satisfactory adhesive and ink-repulsive properties in the resulting plate.

Abstract: A shallow relief printing plate is disclosed having a polymerized layer of less than about 0.020 inch and which includes an array of small protuberances in non-image or background areas to prevent bottoming. Photopolymerizable elements, as well as processing techniques, are also disclosed for making such printing plates.

Abstract: A shallow relief printing plate is disclosed having a polymerized layer of less than about 0.020 inch and which includes an array of small protuberances in non-image or background areas to prevent bottoming. Photopolymerizable elements, as well as processing techniques, are also disclosed for making such printing plates.