Patent GB-1285631-A (GB)
Title: Improvements in the production of spread foams on a substrate
IPC: C08J9/30
Filed: 1969-06-19
Abstract: 1285631 Foam coatings POLYMER CORP Ltd 19 June 1969 [21 June 1968] 31118/69 Heading B2E [Also in Division C3] The surface of a substrate is coated by providing a film-forming aqueous latex composition comprising a latex of curable polymer having at least 40% by weight solids and comprising an emulsifier having the formula: R-N(R 1 )-R 2 -COOM in which R is a C 7 -22 aliphatic group, R 1  is an -R 2 -COOM group, R 2  in each case is a C 1-5  alkylene group and M is a cation, e.g. sodium, potassium, calcium, magnesium or triethanolamine, which renders the emulsifier water soluble, the emulsifier being present in an amount of at least 0.4 part per 100 parts by weight of polymer in the latex composition, the latex composition having a total solids content of at least 60% by weight. adjusting the pH of the latex composition to a value outside the isoelectric range of the emulsifier, foaming the latex composition, spreading a layer of the foam up to a thickness of at most 2 inches uniformly over the surface of the substrate and heating the layer to effect drying and curing, the process being effected without the aid of gelling agents. The polymer in the latex may be natural rubber, polyvinyl chloride, polyvinylidenechloride, polyvinyl acetate, a polyacrylic acid ester or a homopolymer of butadiene, isoprene or chloroprene or a copolymer thereof with styrene, α-methylstyrene, acrylonitrile or acrylic, methacrylic, itaconic, fumaric, maleic or citraconic acid. The emulsifier may be added to the latex composition at any stage and may be used as emulsifier in the emulsion polymerization reactions leading to the preparation of polymer latices. The composition may also contain up to 400 parts by weight of a filler, e.g. calcium carbonate, silica clay, anhydrous aluminium silicate, barytes, talc or lithopone, per 100 parts by weight of polymer latex, 0.2-10 parts by weight per part by weight of the emulsifier of other emulsifiers, e.g. alkali metal or ammonium aliphatic alcohol sulphates, alkyl aryl sulphonates, polyethylene glycol alkyl phenyl ethers, alkali metal or ammonium phosphates or pyro- or polyphosphates or tetraalkyl ammonium halides, and antioxidants, thickeners, foaming aids and curatives, e.g. zinc diethyldithiocarbamate, zinc salt of 2 mercaptobenzothiazole, sulphur, 2, 2'-methylene bis (4-methyl-6-t-butyl phenol), carboxy methyl cellulose, zinc oxide and carbon black. The composition may be foamed by mechanical means in which air or other gaseous medium is incorporated in the latex by vigorous agitation or by the use of chemical foaming agents which decompose to release a gas, e.g. carbon dioxide or ammonia. The substrate is preferably pervious to water vapour and may be a woven, non-woven or knitted fabric, e.g. nylon tricot, cottonduck or the jute backing fabric of a carpet. After spreading on the substrate the layer of foam may be subjected to radiant heat to provide the foam layer with a skin of dried polymer which resists the impingement of streams of heated air and then subjected to drying and curing in a curing oven or by means of radiant heaters.