Abstract: Water-processable screenprinting stencils and resists are based upon photopolymerizable systems in which the hydrogen donor compound is a modified polyvinylalcohol having pendant dialkylamino groups.

Abstract: Substituted dibenzalketones useful as water-soluble photoinitiators have the formula: ##STR1## wherein R.sup.1 and R.sup.2 are 4, alkyl or, taken together, an aliphatic ring, n=0 or an integer and R.sup.3 and R.sup.4 either are both water-solubilizing groups (a) --X(CH.sub.2).sub.m N.sup.+ R.sup.5.sub.3, (b) --X(CH.sub.2).sub.m COO.sup.- M or (c) --X(CH.sub.2).sub.m SO.sup.-.sub.3 M.sub.5 or one is such a group and the other is (d) a group --NR.sup.5.sub.2, X is --CH.sub.2 --, --O-- or --S--, R.sup.5 is an alkyl group, M is H.sup.+ or a metal cation and m=0. Such a photoinitiator compound is associated with a polymerizable compound in an aqueous photopolymerizable composition.

Abstract: Photopolymers which are derivatives of polyvinyl alcohol and are useful as resists, stencils and relief images are made by reacting a compound having one or two formyl or acetal groups, such as terephthaldehyde, a naphthalene dialdehyde or the reaction product of an acetal and hydroxy-benzaldehyde, with an aromatic or heterocyclic compound carrying an acetyl group, so as to produce an intermediate of the formula: ##STR1## and reacting this with a polyvinyl alcohol to yield a photosensitive product of the formula: ##STR2## wherein m is 0 or 1, n is an integer from 1 to 6, X is an aromatic or heterocyclic group carrying at least one polar group and Z is an aromatic group of the formula: ##STR3## wherein R' and R", when both are present, are the same or different and each represents a hydrogen or a halogen atom or an alkyl, alkoxy, hydroxyalkyl, hydroxy, nitro or cyano group.

Abstract: Light-sensitive compositions and materials incorporating such compositions, such as coated films for the production of polymeric resists, comprise a diazo-resin as a sensitizer for the composition and a water-soluble or water-dispersible colloid. In order to stabilize the diazo-resin sensitizer and increase the time between manufacture and use of such light-sensitive compositions and material, a poly-(vinylpyridine) is incorporated in the composition, preferably in the form of a water-soluble salt such as the hydrochloride or sulphate.