GB975461A - Polyether elastomers - Google Patents

Abstract

The invention comprises vulcanizable polyether elastomers composed of polymerized epoxide monomers of which at least 50 mol per cent is styrene oxide or an alkylene oxide having not more than four carbon atoms, or a halogenated derivative of alkylene oxides, the elastomer being substantially amorphous, devoid of spherulite, and having an intrinsic viscosity greater than 3.0. They are prepared by polymerizing in the presence of zinc diethyl and water, either in the absence of a diluent or in presence of one of the following: benzene, toluene, xylene, or mixtures thereof with or without a minor portion by volume of a liquid aliphatic hydrocarbon diluent, benzaldehyde, an alkaldehyde with 2 to 7 carbon atoms, or mixtures thereof, with or without dilution with dioxane or a liquid aliphatic hydrocarbon. The mole ratio of water to zinc diethyl is in the range 0.5 to 1.5:1, preferably 1:1. Specified monomers are ethylene oxide, 1,2-propylene oxide-chloropropylene oxide 1,2-butylene oxide, 2,3-butylene oxide, isobutylene oxide, styrene oxide, and mixtures thereof. A minor portion, preferably 3.5 mol per cent, of an olefinically unsaturated epoxide can be added and copolymerized with the above oxides. Specified unsaturated epoxides are 1-butene-glycidyl ether, vinyl-glycidyl-ether, vinyl-thio-ethyl-glycidyl ether, glycidyl acrylate, glycidyl methacrylate, butadiene monoxide, vinyl-cyclohexene monoxide, allyl-glycidyl ether, and mixtures thereof. Preferably 1.3 moles of zinc diethyl per 100 moles of monomer is used, but as little as 0.2 moles is required. Vulcanization of the saturated elastomer is effected by a mixture of an organic peroxide and a conventional sulphur-bearing agent. In the case of polyethers containing unsaturation a single agent is sufficient. Specified peroxides are di-cumyl peroxide, di-tertiary-butyl hydroperoxide and 2,5-bis (tert.-butyl-peroxy)-2, 5-dimethyl hexane. The examples describe the preparation of: (1) poly-propylene oxide; (2) copolymer of propylene oxide and allyl glycidyl ether; (8) copolymer of propylene oxide and butadiene monoxide; (9) copolymer of propylene oxide and vinylcyclohexene monoxide; (10) copolymer of propylene oxide and glycidyl acrylate; (12) polymer of styrene oxide; (13) polymer of butylene oxide. In examples (18)-(20) poly propylene oxide is vulcanized in presence of various quantities of di-cumyl peroxide, sulphur, phenylb -naphthaline (as antioxidant), and carbon black (as reinforcing agent). In example (21) copolymer of example (7) is vulcanized in presence of sulphur, stearic acid, zinc oxide, carbon black, tetramethyl thiuram disulphide and tellurium diethyl dithiocarbonate (the latter two being accelerators). Properties of the rubbers are also shown in the examples, and a comparison table of rubber of example (21) and several other known rubbers is given.