GB828814A - Improvements in or relating to elastomeric addition products - Google Patents

Abstract

An elastomeric addition product having a Mooney plasticity on the large motor at 100 DEG C. of not less than 35 is obtained by reacting in the presence of a catalyst system and in the absence of substantial amounts of oxygen (A), at least 30% of the double bonds present in at least one synthetic rubber latex containing an emulsion polymerized polymer of at least one conjugated diolefin having 4-6 carbon atoms with from none to an equal amount by weight of at least one monomer containing a reactive component selected from the group consisting of vinyl and vinylidene radicals which are polymerizable with the diolefin with (B) at least one aliphatic monomercaptan having 1-6 carbon atoms, removing unreacted mercaptan from the reaction mixture and isolating the addition product. The latex may be obtained by polymerizing butadiene, isoprene, dimethyl butadiene, methyl pentadiene, piperylene or 2-chlorobutadiene 1,3; or copolymers of these monomers with styrene, para methyl styrene, ortho-para dimethyl styrene, para methoxy styrene, chloro and bromo styrenes, alpha methyl styrene, alpha-para dimethyl styrene, acrylic and methacrylic acid, methyl and ethyl acrylate, methyl or ethyl methacrylate, vinyl pyridines, 2-vinyl pyridine, 2 - methyl - 5 - vinyl pyridine, vinylidene chloride, acrylonitrile and methacrylonitrile. The latices may be prepared according to the "hot rubber" processes using as emulsifying agent an ammonium or alkali metal salt of stearic, palmitic or oleic acids, or hydrogenated tallow acids or hydrogenated rosin acids or sodium salts of alkylated benzene, or naphthalene sulphonic acids and sodium lauryl sulphate, and using as catalyst potassium persulphate, alkali metal salts of perborates, benzoyl peroxide or hydrogen peroxide, octyl, dodecyl, hexadecyl, octadecyl or benzyl mercaptan, according to the "cold process" using as catalyst sodium formaldehyde sulphoxylate, an organic hydroperoxide and an iron salt, a mixture of a polyethylene polyamine, an iron salt and an organic hydroperoxide, a mixture of an iron-pyrophosphate complex and an organic hydroperoxide, or a mixture of an iron-ethylenediamine tetra-acetic acid complex and an organic hydroperoxide at 41-55 DEG F. The mercaptans used in the manufacture of the addition product may be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, isoamyl and hexyl mercaptans. The catalysts which may be used in the preparation of the addition product may be azodi-isobutyronitrile, dimethyl azo isobutyrate, or cumene hydroperoxide or para-menthane hydroperoxide alone or in admixture with (1) sodium formaldehyde sulphoxylate and an iron salt (2) a polyethylene polyamine (3) an iron-ethylene diamine tetra-acetic acid complex or (4) an iron-pyrophosphate complex. The addition is preferably effected at 50-65 DEG C. A processing oil may be used in an amount of 5 to 100 parts of the addition product, and natural rubber, reclaimed rubber, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer and polymerized 2-chlorobutadiene, polystyrene resins, copolymers of styrene and monomethyl styrene, copolymers of styrene and anthracene, copolymers of styrene and actylonitrile, phenolformaldehyde resins and melamine resins may also be added. The compounded addition product may then be mixed with zinc oxide stearic acid, sulphur, mercaptobenzthiazole and styrenated phenol and the whole cured for 90 minutes at 275 DEG F.