Patent GB-631031-A (GB)
Title: Improvements in the manufacture of sponge rubber
IPC: C08J9/00
Filed: 1947-06-25
Abstract: A synthetic rubber latex composition contains a gelling agent and a stabilizing agent having the formula RCO(OC2H4)nOH, where R is a straight chain alkyl radical having from 8 to 20 carbon atoms, and n is at least 4, the stabilizing agent being soluble in water, preferably at least to the extent of 2.5 parts by weight in 100 parts of water, and being such that a precipitate is formed between 180 DEG F. and 210 DEG  F. when a 1 per cent aqueous solution of the compound is heated, preferred stabilizing agents being nona-ethylene glycol monoleate and other compounds which satisfy the conditions, obtained by reacting polyethylene glycols with higher fatty acids.  Preferably the composition contains between 1 and 28 parts by weight of the stabilizing agent for every 100 parts dry weight of synthetic rubber in the latex, and the gelling agent is preferably a delayed or heat-sensitive gelling agent such as sodium, potassium or barium fluosilicate or a mixture of zinc oxide and an ammonium salt such as ammonium chloride.  The synthetic rubber latex used is preferably one produced by conventional emulsion-polymerisation methods, and may contain a polymer of butadiene-1,3, methyl-2-butadiene-1,3, chloro-2-butadiene-1,3, piperylene or 2,3-dimethylbutadiene-1,3, or may be a copolymer of one of the above with compounds containing a CH2 = C< group such as styrene, vinyl naphthalene, acrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile, methacrylamide, isobutylene, methyl vinyl ether, methyl vinyl ketone, and vinylidene chloride.  Usual compounding ingredients such as sulphur, anti-oxidant, and accelerator of vulcanization may be incorporated.  Sponge rubber may be made by forming a foam of the composition, shaping the foam, causing the foam to gel, preferably p  by heating at a temperature at which flocculation of the stabilizing agent occurs, and vulcanizing the gelled foam. Specification 380,431 is referred to.ALSO:A natural or synthetic rubber latex composition contains a gelling agent and a stabilising agent having the formula RCO(OC2H4)nOH where R is a straight chain alkyl radical having from 8 to 20 carbon atoms, and n is at least 4, the stabilising agent being soluble in water, preferably at least to the extent of 2.5 parts by weight in 100 parts of water, and being such that a precipitate is formed between 180 DEG F. and 210 DEG  F. when a 1 per cent aqueous solution of the compound is heated, preferred stabilising agents being nona-ethylene glycol monoleate and other compounds which satisfy the conditions, obtained by reacting polyethylene glycols with higher fatty acids.  Preferably the composition contains between 1 and 28 parts by weight of the stabilising agent for every 100 parts dry weight of rubber in the latex.  The gelling agent is preferably a delayed or heat-sensitive gelling agent such as sodium, potassium or barium fluosilicate or a mixture of zinc oxide and an ammonium salt such as ammonium chloride, and when synthetic rubber latex is employed it is preferably formed from neoprene or butadiene-styrene or butadiene-acrylonitrile copolymer.  Usual compounding ingredients such as sulphur, antioxidant and accelerator of vulcanization may be incorporated. Sponge rubber may be made by forming a foam of the composition, shaping the foam, causing the foam to gel, preferably by heating at a temperature at which flocculation of the stabilising agent occurs, and vulcanizing the gelled foam. Specification 380,431, [Group IV], is referred to.