Patent GB-1092688-A (GB)
Title: Process for preparing solid foam from latexes
Inventor: BAILEY HERBERT ROYLSTON
IPC: C08J9/30
Filed: 1966-03-30
Abstract: A solid plastic foam is produced from an aqueous colloidal dispersion of a polymeric material consisting of at least 80% by weight of at least one substantially water-insoluble, emulsion polymerizable, non-surface active, ethylenically unsaturated compound by mixing the latex with a plasticizer to the polymeric material, foaming the resulting mixture to give a wet froth, heating until it gels and water and other volatile ingredients have been driven off and then heating at a higher temperature to fuse the gel.  A preferred latex is of a copolymer which latter is obtained by using as a comonomer up to 20% of an emulsion polymerizable, ethylenically unsaturated compound having at least one pendant surface activity producing substituent group. Examples of the latter are vinyl and allyl sulphonic acids and salts; a ,b -ethylenically unsaturated carboxylic acids such as acrylic, methacrylic &c., sulphoalkyl esters of these such as 2-sulphoethyl acrylates, amides, N-hydroxy alkyl substituted derivatives and hydroxy alkyl esters; vinylidene aromatic compounds with surface activity producing groups in the benzene ring; vinyl benzyl compounds; vinyl ether amines; ethylenically unsaturated nitrogen containing heterocyclic compounds and lower alkoxy polyethylene glycol esters of acrylic and methacrylic acids. Preferred monomers are compounds having sulpho and carboxyl groups, especially in sodium or potassium salt form. Examples of the main monomer are styrene, and lower alkyl substituted styrenes, vinyl naphthalene, methoxy-, cyano-, acetyl- and halostyrenes, alkyl methacrylates, alkyl and phenyl acrylates, acrylo- and methacrylonitrile, ethyl a -chloroacrylate, diethyl maleate, vinyl chloride and bromide, vinyl methyl ketone, methyl isopropenyl ketone, vinyl ethyl ether, 1:3-butadiene and isoprene.  The polymer concentration in the latex should be at least 50% by weight. Non-fugitive plasticizers which can be used are dioctyl azelate, dioctyl sebacate, tricresyl phosphate, butyl-benzyl phthalate, di-2-ethyl hexyl phthalate, dioctyl adipate, ethyl phthalyl ethyl glycollate, 2 - ethyl hexyl diphenyl phosphate, butyl phthalyl butyl glycollate, glyceryl mono-oleate, acetyl tributyl citrate, di-isobutyl adipate, liquid butadiene-acrylonitrile copolymers, liquid polybutenes.  The amount of plasticizer must be such that a fused blend of the plasticizer and polymer is inherently film-forming at 177 DEG  C. but solid at room temperature.  Inorganic fillers, heat stabilizers, anti-oxidants, froth stabilizers, vulcanizing agents and accelerators may be added.  The aqueous dispersion is foamed by whipping or beating, preferably, but can also be done by introducing a non-coagulable gas.  The foam is heated at a temperature from 67-177 DEG  C. to gel and drive off the water and the temperature will then rise to the temperature of the drying apparatus to fuse the gel.ALSO:A foam backed sheet material is prepared by applying to the material a wet froth of a latex of an addition polymer of an unsaturated compound and a plasticiser, heating the froth to gel it and expel the water and then heating further to fuse the gel. Suitable materials to which the foam will adhere are cloth, leather, plastic, paper, wood and asbestos.  The polymers are derived from at least 80% by weight of an unsaturated compound such as styrene or vinyl chloride preferably with up to 20% of a monomer having a surface activity producing substituent group. Many examples of suitable polymers are given.  (Div. C3).