The British Petroleum Company, P.l.c.

Frank C Robertson

Sidney G Fogg

Douglas Wilson

A water soluble copolymer of polymerizable esters of unsaturated carboxylic acids having the hydrazide group as a substituent comprises a major proportion of monomer units which are methyl acrylate and/or methyl methacrylate and a minor proportion of co-monomer units which are one or more alkyl esters of acrylic acid or methacrylic acid wherein the alkyl group comprises at least four carbon atoms. The copolymer has film forming properties which make it useful for use in protective coatings. The invention includes a film forming composition comprising the copolymer and a cross-linking agent which cross-linking agent is an aldehyde or an organic thermosetting resin containing methylol or methoxy groups, the copolymer and cross-linking agent being dissolved in an aqueous medium in amounts such that they will form a film when applied to a surface. The composition is applied to a surface and heated at 120.degree. to 180.degree. C. for from 5 mins to 4 hours to produce a water insoluble coating from a water based composition containing the water soluble copolymer.

Copolymer, a film forming composition and a method of coating a surface

A water soluble copolymer of polymerizable esters of unsaturated carboxylic acids having the hydrazide group as a substituent comprises a major proportion of monomer units which are methyl acrylate and/or methyl methacrylate and a minor proportion of co-monomer units which are one or more alkyl esters of acrylic acid or methacrylic acid wherein the alkyl group comprises at least four carbon atoms. The copolymer has film forming properties which make it useful for use in protective coatings. The invention includes a film forming composition comprising the copolymer and a cross-linking agent which cross-linking agent is an aldehyde or an organic thermosetting resin containing methylol or methoxy groups, the copolymer and cross-linking agent being dissolved in an aqueous medium in amounts such that they will form a film when applied to a surface. The composition is applied to a surface and heated at 120.degree. to 180.degree. C. for from 5 mins. to 4 hours to produce a water insoluble coating from a water based composition containing the water soluble copolymer.

A method for reducing formation permeability comprising mixing (a) a homopolymer or copolymer of methyl acrylate or hydroxy alkyl acrylate, where the alkyl group is C.sub.2, C.sub.3 or C.sub.4, into which polymer hydrazide groups have been introduced, and (b) an aldehyde cross-linking agent, dispersing the mixture in an aqueous medium and injecting the aqueous dispersion into a formation, the amounts of the polymer and aldehyde being such that they will form a gel in the aqueous medium. The invention includes compositions for use in the method.

Hydrazide containing polymers

A method of treating salt water-in-oil dispersions comprises mixing with the dispersion a latex of a rubber having a high wet gel strength. The incorporation of the latex into the dispersion causes exudation of water from the dispersion with resulting thickening. If sufficient latex is used the dispersion may be transformed into a solid. Suitable rubbers include natural rubber, polychloroprene rubber, butadiene acrylonitrile rubber, styrene butadiene rubber and poly (methyl methacrylate) graft natural rubber. The tackiness of solids formed using for example a natural rubber latex can be reduced by using in addition to the natural rubber latex, a latex of a low or zero wet gel strength polymer e.g. PVC, poly (vinyl acetate) or polystyrene. The effectiveness of the method of treatment may be improved by the use of a suitable compatible solvent e.g. toluene or a filler such as a clay filler.

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Woking, United Kingdom

Frank C Robertson