Patent GB-1132568-A (GB)
Title: An improved polymerisation process
IPC: C09J7/38
Filed: 1967-10-24
Abstract: 1,132,568. Emulsion polymerization. KENDALL CO. 24 Oct., 1967 [7 Nov., 1966], No. 48248/67. Heading C3P. An aqueous emulsion polymerization consists of forming a reaction mixture of water, copolymerizable monomers of which a major portion is a mixture of alkyl acrylate or methacrylate esters of 1 to 10 carbon atoms in the alkyl group, and a carboxylic acid constituent, and a base reactable with the carboxylic acid to form a water soluble salt in an amount to ensure dispersion of the monomers on agitation, agitating the mixture and polymerizing the dispersion so formed. The carboxylic acid is an amic acid or acid ester of formula or wherein X for an acid ester monomer represents -COOR or or -CONRR<SP>1</SP> in the case of an amic acid, R is an alkyl group, R<SP>1</SP> is either hydrogen or an alkyl group containing from 1 to 10 carbon atoms and R<SP>11</SP> and R<SP>111</SP> are either hydrogen or a methyl group and the carboxylic acid is further characterized by being, (a) an individual amic acid monomer in which the R group contains 10-24 carbon atoms, (b) a mixture of amic acid monomers containing 1-28 carbon atoms in their R groups and an average number of carbon atoms in the R groups of 10-24, (c) an individual acid ester monomer in which the R group contains 6-24 carbon atoms, (d) a mixture of acid ester monomers containing 1-28 carbon atoms and an average of 6-24 carbon atoms in their R groups, or (e) mixtures of (a) and (c) monomers, (a) and (d) monomers, (b) and (c) monomers or (b) and (d) monomers. Suitable base compounds are, ammonium hydroxide, sodium or potassium hydroxide, an alkyl tertiary amine, or dimethylethanol amine. An ethylenically unsaturated monomer, other than the ester or acid monomers, capable of addition polymerization, may be included in the monomeric constituents; examples of such compounds are lauryl and stearyl methacrylate. Pressureadhesive polymers may be prepared by this process, from monomers consisting of 30-95 parts of the ester monomer, and 70-5 parts of: (i) a mixture of amic acids of the (b) group in which the acids which contain more than 6 carbon atoms in the R groups are acids containing branched alkyl groups; or (ii) a mixture of acid esters of (d) group in which the R groups contain an average of at least 8 carbon atoms and the acid esters which contain more than 6 carbon atoms in the alkyl groups, contain branched alkyl groups. The mixture of monomers is a liquid to semi-solid viscous non-crystalline composition. After polymerization, an acid may be added to the dispersion to neutralize the base and convert the carboxylate salt groupings of the polymer to carboxylic acid groups, thereby coagulating the dispersion. Alternatively when a volatile base is used, this may be removed by heating, resulting in the evaporation of the base and coagulation of the dispersion. Coagulation may also be achieved by mixing the dispersion with a water-miscible, organic, liquid, polar compound. In the examples, monomer mixtures of ethyl acrylate, 2-ethyl hexyl acrylate and optionally acrylic acid, are co-polymerized with one of the acids listed below, in the presence of a redox catalyst system such as a mixture of a peroxide, persulphate and ferrous sulphate, using as a base one of the following: ammonium, sodium or potassium hydroxide, or dimethylethanolamine. The acid used is one of the following: " N-t-G 2  maleamic acid " or its ammonium salt (this acid is a mixture of maleamic acids prepared by the amidation of maleic anhydride with a complex mixture of t-alkyl primary amine such as " Primene 81-R " (" Primene " is a Registered Trade Mark)), " N-t-C 9  maleamic acid ", or tridecyl acid maleate or fumarate. In the example using the ammonium salt of " N-t-G 2  maleamic acid ", " N-t-C 12  acrylamide " (prepared by amidation of acryl chloride with " Primene 81-R ") was also incorporated in the monomer mixture.