Wash-off film containing synthetic amphoteric polymers
AssigneeE. I. Du Pont de Nemours and Company
InventorsRobert P. Foss, Daniel R. Fruge
Life of this patent
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Abstract
Sharper edges are obtained in silver halide wash-off films for tanning development when from 5 to 60% of the unhardened gelatin binder in one or more layers is replaced with a synthetic amphoteric polymer consisting essentially of at least one of each of three constituents: (a) carboxylic acid, (b) alkyl primary amine, and (c) secondary and/or tertiary amine, the amphoteric polymer having an isoelectric point of from 4 to 8.
Claims26
A wash-off film for tanning development comprising at least one unhardened gelatin-containing layer of which at least one gelatin-containing layer is an unhardened silver halide emulsion with a gelatin binder, the improvement wherein 5 to 60% by weight of the gelatin in at least one of the gelatin-containing layers is replaced with a water soluble synthetic acrylic amphoteric addition polymer consisting essentially of at least one of each of three constituents:
- (a) carboxylic acid selected from the group consisting of acrylic acid and methacrylic acid, (b) acrylic alkyl primary amine, and (c) acrylic secondary and/or tertiary amine, constituents (a), (b) and (c) being present in 10 to 60 mole percent, 1 to 20 mole percent, and 10 to 60 mole percent, respectively, based on the total moles of the amphoteric polymer whereby a sharper wash-off image is obtained by incorporation of the amphoteric polymer.
A process for preparing a wash-off film for tanning development which comprises
- (a) preparing by emulsion polymerization in a reaction medium a prepolymer by reacting methyl acrylate and one or more acrylic monomers having secondary and/or tertiary amine functionality:
- (b) hydrolyzing the methyl acrylate moiety of the prepolymer to acrylic acid groups;
- (c) neutralizing the reaction medium;
- (d) reacting acrylic acid groups of the prepolymer with ethyleneimine or propyleneimine to form an amphoteric polymer with pendant alkyl primary amine groups;
- (e) separating the acrylic amphoteric polymer from the reaction medium:
- (f) incorporating the acrylic amphoteric polymer into an unhardened gelatino-silver halide wash-off emulsion, the acrylic amphoteric polymer replacing 5 to 60% of the gelatin binder of the unhardened gelatino-silver halide emulsion.
A process for preparing a wash-off film for tanning development which comprises
- (a) preparing a solution of at least one acrylic monomer having a primary amine functionality and at least one acrylic monomer having a secondary and/or tertiary amine functionality;
- (b) adding acid to protonate the amine monomers;
- (c) adding acrylic and/or methacrylic acid monomer;
- (d) heating the solution of monomers in the presence of a polymerization initiator to react the monomers and cooling to ambient temperature whereby an acrylic amphoteric polymer is formed;
- (e) neutralizing excess acid from the acrylic amphoteric polymer;
- (f) separating the acrylic amphoteric polymer from the solution;
- and
- (g) incorporating the acrylic amphoteric polymer into an unhardened gelatino-silver halide wash-off emulsion, the acrylic amphoteric polymer replacing 5 to 60% of the gelatin binder of the unhardened gelatino-silver halide emulsion.
Dependencies are inferred from the claim text.