GB1049027A - Spontaneously cross-linking polymers - Google Patents

Abstract

Spontaneously cross-linking copolymers are prepared by copolymerizing, in an aqueous medium containing from 0.01 to 5% by weight of a polymerization catalyst and from 0.5 to 20% by weight of an emulsifier, (a) 0.5 to 40% (based on the total monomer weight) of a monomer of the formula <FORM:1049027/C3/1> in which R is hydrogen or a methyl group and X is an organic radical which is bonded to the -CH2- group by way of nitrogen and which contains at least one grouping of the formula <FORM:1049027/C3/2> in which R1 represents an alkyl group; (b) 0 to 20% of a polymerizable, monoolefinically unsaturated compound containing either an amido group or at least one hydroxyl group; (c) 0 to 20% of a compound of the formula <FORM:1049027/C3/3> in which R is hydrogen or a methyl group and R11 is a C1-C8 alkyl radical or a carboxylic acyl radical; (d) 99.5 to 40% of at least one polymerizable vinyl compound, which is a (C1-C12 alkyl) ester of acrylic acid, a (C8-C12 alkyl) ester of methacrylic acid, a C4-C6 conjugated aliphatic diene or a vinyl (C1-C4 alkyl) ether; (e) 0 to 50% of at least one polymerizable vinyl compound which is an aromatic monovinyl compound of the benzene series, an a ,b -olefinically unsaturated aliphatic nitrile, a vinyl or vinylidene halide, a (C1-C4 alkyl) ester of methacrylic acid, an a ,b -olefinically unsaturated aliphatic monocarboxylic acid, a vinyl ester of a C2-C3 carboxylic acid, or itaconic acid. Monomers (a) exemplified are the acyclic and heterocyclic compounds obtained by reacting acrylamide or methacrylamide with various melamine or urea derivatives containing at least two <FORM:1049027/C3/4> groups (1 mole of alcohol R1OH being evolved in the reaction). Monomers (b) specified are acrylamide, methacrylamide, and the esterification products of 1 mole of an a ,b -olefinically unsaturated monocarboxylic acid such as acrylic or methacrylic acid with 1 mole of a polyhydric alcohol such as ethylene, propylene or butylene glycol, glycerol trimethylolpropane or pentaerythritol, e.g. b -hydroxy ethyl acrylate or methacrylate and b -hydroxy-n-propyl acrylate or methacrylate. Up to 5% by weight of a compound containing a plurality of non-conjugated polymerizable groups, e.g. divinyl benzene, may be included in the monomer reactants. The emulsifier used may be of the cationic, anionic or nonionic type or a combination thereof (several examples of each type are disclosed). Polymerization is generally effected at 10-80 DEG C. and at a pH of from 4 to 9. A dispersed organic solvent may be included in the aqueous polymerization medium. Catalysts specified are potassium and ammonium persulphate, hydrogen peroxide, percarbonates, benzoyl peroxide, t.-butyl hydroperoxide, cumene hydroperoxide, p-menthane hydroperoxide and di-t.-butyl peroxide; and combinations thereof with reducing agents such as sodium pyrosulphite or bisulphite, sodium formaldehyde sulphoxylate and triethanolamine. Molecular weight regulators may be used, e.g. alkyl mercaptans and diisopropyl xanthate. Some or all of the monomers may be added in portions or continuously during polymerization, and the process can be conducted in two or more stages with different monomer compositions, if desired, at each stage. In one example (16) polymerization is terminated at 80% monomer conversion by the addition of sodium dithionite. The process may also be applied to the production of graft polymers, the specified monomers being copolymerized in the presence of 3 to 50% by weight (based on the total weight of monomers and polymer) of polymers or copolymers of conjugated diolefines, e.g. butadiene, or other preformed polymers which contain free olefinic double bonds. The copolymer dispersions are useful for coating paper and leather.ALSO:Aqueous dispersions suitable for coating paper and leather comprise together with an emulsifier (cationic, anionic or non-ionic) a spontaneously cross-linking copolymer of (a) 0.5 to 40% (based on the total monomer weight) of a monomer of the formula <FORM:1049027/B1-B2/1> in which R is hydrogen or a methyl group and X is an organic radical which is bonded to the -CH2-group by way of nitrogen and which contains at least one grouping of the formula <FORM:1049027/B1-B2/2> in which R1 represents an alkyl group; (b) 0 to 20% of a polymerisable, monodefinically unsaturated compound containing either an amido group or at least one hydroxyl group; (c) 0 to 20% of a compound of the formula <FORM:1049027/B1-B2/3> in which R is hydrogen or a methyl group and R11 is a C1 - C8 alkyl radical or a carboxylic acyl radical; (d) 99.5 to 40% of at least one polymerizable vinyl compound, which is a (C1 - C12 alkyl) ester of aerylic acid, a (C8 - C12 alkyl) ester of methacrylic acid, a C4 - C6 conjugated aliphatic diene or a vinyl (C1 - C4 alkyl) ether; (e) 0 to 50% of at least one polymerizable vinyl compound which is an aromatic monovinyl compound of the benzene series, an a , b -definically unsaturated nitrile, a vinyl or vinylidene halide, a (C1 - C4 alkyl) ester of methaerylic acid, an a , b -definically unsaturated aliphatic monocarboxylic acid, a vinyl ester of a C2 - C3 carboxylic acid, or itaconic acid. The copolymer can be one wherein the monomers specified above are graft polymerized on to an unsaturated polymer such as a conjugated diene polymer, e.g. polybutadiene.