Polyvinyl acetal with hydroxy aliphatic acetal groups useful in photosensitive negative working compositions
AssigneeHoechst Aktiengesellschaft
InventorGeorg Pawlowski
Life of this patent
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Abstract
A polyvinyl acetal is described which contains 4 to 40 mol-% vinyl alcohol units, 1 to 20 mol-% vinyl acetate units, 0 to 85 mol-% vinyl acetal units derived from an aldehyde free of OH groups and 1 to 85 mol-% vinyl acetal units derived from an aldehyde containing OH groups. The polymer is suitable as binder for photosensitive mixtures, in particular for the preparation of printing plates and photoresists. The layers obtained therewith can be developed with neutral or weakly alkaline, purely aqueous solutions and produce printing plates with a high print run performance and good ink receptivity.
Claims9
A photosensitive mixture comprising:
- (A) a negative-working light-hardenable substance selected from the group consisting of:
- (1) a diazonium salt polycondensation product containing diazonium salt units and non-photosensitive units derived from compounds capable of condensation and selected from the group consisting of aromatic amines, phenols, phenol ethers, aromatic thioethers, aromatic hydrocarbons, aromatic heterocyclic compounds and organic acid amides, and
- (2) a mixture of olefinically unsaturated, radically polymerizable compound and a photoinitiator for radical polymerization
- in admixture with
- (B) a polyvinyl acetal having a hydroxyl number of from 150 to 600,
- wherein the light-hardenable substance and the polyvinyl acetal are present in amounts sufficient to produce an image when exposed to actinic radiation and developed wherein the polyvinyl acetal is a compound of the formula ##STR4## wherein R.sup.1 is a radical selected from the group consisting of ##STR5## R.sup.2 is a hydrogen atom, a substituted or unsubstituted alkyl radical containing 1 to 6 carbon atoms, or a substituted or unsubstituted aryl radical,
- R.sup.3 is an alkyl radical containing 1 to 4 carbon atoms,
- R.sup.4 is a substituted or unsubstituted alkylene group containing 1 to 6 carbon atoms,
- R.sup.5 and R.sup.6 are identical or different and denote hydrogen atoms, alkyl radicals containing 1 to 6 carbon atoms, alkoxy radicals containing 1 to 4 carbon atoms, or hydroxyalkyl radicals containing 1 to 3 carbon atoms or hydroxyl groups,
- R.sup.7 is a hydrogen atom or an alkyl radical containing 1 to 6 carbon atoms,
- R.sup.8 is a hydrogen atom, an alkyl, hydroxyalkyl or alkoxyalkyl radical containing 1 to 6 carbon atoms or a substituted or unsubstituted aryl radical containing 6 to 10 carbon atoms,
- a is a number from 0.05 to 0.8,
- b is a number from 0.2 to 0.6,
- c is a number from 0.01 to 0.15,
- d is a number from 0.04 to 0.2, and the sum of a+b+c+d=1.
Dependencies are inferred from the claim text.