Patent GB-1073392-A (GB)
Title: Improvements in or relating to processes of preparing vinyl halide polymers
IPC: C08F14/20
Filed: 1965-01-25
Abstract: A process for preparing vinyl fluoride polymers of controlled particle size comprises polymerizing at elevated temperature, under superatmospheric pressure and with agitation, a monomeric material comprising at least 50% by weight of a vinyl fluoride, the monomeric material being suspended in an aqueous medium in the presence of a monomer-soluble, free radical generating polymerization catalyst and at least one water-insoluble, finely divided, inert solid material having an average particle size in the range 0.01 to 3 microns, and thereafter recovering the resulting polymer.  Other monomers which may be present include vinyl chloride, vinyl bromide, vinylidene fluoride, tri- and tetrahaloethylenes, and acrylic and methacrylic acids, esters, nitriles, amides, anhydrides and acid halides. Specified solids include metals, metal oxides, metal salts, polymeric materials and organic dyestuffs. Specified catalysts are benzoyl and lauroyl peroxides, and polymerization may be effected in the presence of anionic, cationic or non-ionic emulsifiers, or suspending agents such as carboxymethyl cellulose, polyvinyl alcohol and gelatine. The polymers may be dispersed in latent solvents, e.g. dimethyl acetamide, to give coating compositions.  In examples vinyl fluoride is polymerized in aqueous media in the presence of lauroyl peroxide, methyl cellulose, isopropanol and (1, 4 and 5) titanium dioxide, (3) titanium dioxide and a non-ionic surface active agent, (6 and 7) calcium carbonate, (8) titanium dioxide and calcium carbonate, (9) zinc oxide and titanium dioxide, (10) zinc oxide and calcium carbonate and (11) titanium dioxide.ALSO:Substrates such as metals may be coated with dispersions of vinyl fluoride polymers prepared by polymerising at elevated temperature under superatmospheric pressure with agitation, a monomeric material comprising at least 50 weight per cent of vinyl fluoride suspended in an aqueous medium in the presence of a monomer-soluble, free radical polymerisation catalyst and at least one finely divided inert solid material of average particle size 0.01 to 3 microns.  The polymers are preferably applied dispersed in latent organic solvents such as dimethyl acetamide. The vinyl fluoride may be copolymerised with vinyl chloride, vinyl bromide, vinylidene fluoride, tri- and tetrahaloethylenes, and acrylic and methacrylic acids, esters, nitriles, amides, anhydrides and acid halides.  Many suitable inert solid materials are listed, including metals, metal oxides, metal salts, polymeric materials and organic dyestuffs specified catalysts are benzoyl and lauroyl peroxides, and polymerisation may be effected in the presence of anionic, cationic and non-ionic emulsifiers, and organic suspending agents, e.g. carboxymethyl cellulose, polyvinyl alcohol and gelatin. In examples metal panels are coated with dimethyl acetamide dispersions of polymers prepared by polymerising vinyl fluoride in aqueous media in the presence of lauroyl peroxide, methyl cellulose, isopropanol and (1, 4 and 5) titanium dioxide, (3) titanium dioxide and a non-ionic surface active agent, (6 and 7) calcium carbonate, (8) titanium dioxide and calcium carbonate, (9) zinc oxide and titanium dioxide, (10) zinc oxide and calcium carbonate and (11) titanium dioxide.