Patent GB-749339-A (GB)
Title: Manufacture of foamed latex sponge
IPC: C08J9/00
Filed: 1954-04-13
Abstract: Glass fibres are incorporated in a synthetic rubber latex when making a foamed latex sponge by adding them in the form of an aqueous slurry containing a cationic surfaceactive agent. Specified latices are those of polymers of butadiene, isoprene, chloroprene, piperylene and dimethyl butadiene or their copolymers with styrene, vinyl naphthalene, acrylic acid, methyl acrylate or methacrylate, acrylo- or methacrylo-nitrile, methacrylamide, methyl vinyl ether or ketone and vinylidene chloride.  Specified cationic emulsifying agents are trimethyl, or dimethyl hexadecyl, octadecyl ammonium chloride, lauryl pyridinium chloride, cetyl dimethyl benzyl ammonium chloride, N - stearyl - betaine, octadecylamine acetate, hexadecyl di-(polyoxyethylene) amine and oleyl diethylethylene diamine. Natural rubber latex and, as foaming agent, an anionic surface-active agent, e.g. soap, alkyl sulphonate or sulphate and sulphonated ethers may also be present in the latex while the slurry may contain a nonionic surface-active agent.  The compounded latices may be foamed, a gelling agent added, the foam shaped, gelled and vulcanized.ALSO:In the manufacture of foamed latex sponge, glass fibres are incorporated in a natural and/or synthetic rubber latex in the form of an aqueous slurry of glass fibres containing a cationic surface-active agent for preventing agglomeration of the fibres. The synthetic rubber latex may comprise a butadiene polymer or a copolymer of butadiene and a compound copolymerizable therewith, e.g. styrene.  The cationic surface active agent may be a quarternary ammonium salt in which at least one of the radicals attached to the nitrogen atom has from 8 to 24 carbon atoms, e.g. trimethyl octadecyl ammonium chloride, or amines, amides, or diamines having an organic group containing from 8 to 24 carbon atoms, or their acid salts, e.g. oleyl diethylethylene, diamine, and octadecyl-amine acetate.  The amount of cationic surface-active agent used is preferably 0.2 to 10 per cent by weight of the glass fibres.  The glass fibres may be of sodium-boron glass of 0.0002 to 0.0007 inch diameter and from 1/32 to 1/2 inch length, and are preferably 0.00038 inch diameter and 1/8 inch length.  To facilitate mixing with the latex the glass fibre slurry may contain 0.1 to 10 per cent by weight of a non-ionic surface active agent such as a poly-ethylene-glycol alkylphenyl ether, or a mono-ether or a monoester of a polyglycol &c.  The latex may contain as a foaming agent 0.5 to 10 per cent (by weight of rubber) of an anionic surface-active agent such as a soap, an alkyl sulphonate or sulphate, sulphonated ether, &c.  In an example to 159 parts of natural rubber latex are added 2 parts sulphur, 1.25 parts of the zinc salt of mercaptobenzthiazole and 1 part anti-oxidant, as dispersion pastes with an anionic surface-active agent, and aqueous solutions of 1.5 parts potassium oleate, and 1 part tri-ethyl trimethylene triamine. With the prepared latex is mixed an aqueous slurry comprising 33 parts sifted glass fibres, 65 parts water, 0.5 parts of a cationic surface-active agent consisting of the acetate salt of a mixture of hexadecyl, octadecyl, and octadecenyl amines, and 0.66 parts of poly-ethylene-glycol monoisooctyl-phenyl ether.  To the mixture are added aqueous pastes of zinc oxide and zinc diethyl dithiocarbamate containing an anionic surface-active agent, and air is beaten into the mixture to produce a foam to which sodium silico fluoride is added aqueous pastes of zinc oxide and room temperature and then vulcanized at 212 DEG F.  In an alternative method the glass fibre slurry with sodium silicofluoride are added to latex foam prepared as above but without the glass fibre slurry.