Patent GB-970271-A (GB)
Title: A method of applying adherent layers of a foamed material
Inventor: WESSER DIETER
Filed: 1960-12-03
Abstract: A layer of foamed thermoplastic synthetic material is formed on a surface by spraying a mixture of the material and a foaming agent which evolves gas when heated, through a zone of sufficiently high temperature to melt the material and cause the foaming agent to evolve gas, so that the material is sprayed and foamed simultaneously. Layers of differing cell structure may be formed or superimposed, or metallic foils may be fixed between two layers, or a plastic film or non-porous finishing coat may be applied.  In examples (1) azo-isobutyric acid dinitrile is mixed with emulsion type polyvinylchloride powder and sprayed by a hot-medium spray-gun; (2) the spraying mixture may be produced (a) by dissolving the p.v.c. and azo-isobutyric acid nitrile in tetrahydrofurane, removing the latter by distillation and drying, and powdering the residue; (b) by dissolving azo-isobutyric acid dinitrile in methylene chloride, adding p.v.c. powder, which is thereby swollen, and thereafter dried; (c) by mixing p.v.c. powder mechanically with azo-dicarboxylic acid amide to form a granulated material which is then reduced in a hammer-mill; (d) by mixing p.v.c. powder with dibutyl phthalate without causing gelation and then mechanically incorporating azo-isobutyric acid dinitrile. Other spraying mixtures mentioned include: polycaprolactam and dinitroso-pentamethylene diamine; polyvinylchloride and azo-butyric acid dinitrile or azo-hexahydrobenzene nitrile; polyethylene and benzene-1, 3-disulphohydrazide; polyvinylacetate and azo-isobutyric acid dinitrile; and polyvinylchloride with a mixture of benzene-1, 3-disulphohydrazide and azo-isobutyric acid dinitrile. Specification 840,663 is referred to.ALSO:A layer of foamed thermoplastic synthetic material is formed on a surface by spraying a mixture of the material and a foaming agent which evolves gas when heated, through a zone of sufficiently high temperature to melt the material and cause the foaming agent to evolve gas, so that the material is sprayed and foamed simultaneously.  Layers of differing cell structure may be formed or superimposed, or metallic foils may be fixed between two layers, or a plastic-film or non-porous finishing coat may be applied.  In examples (1) azoisobutyric acid dinitrile is mixed with emulsion type polyvinylchloride powder and sprayed by a hot-medium spray-gun; (2) the spraying mixture may be produced (a) by dissolving the p.v.c. and azo-isobutyric acid nitrile in tetrahydrofurane, removing the latter by distillation and drying, and powdering the residue; (b) by dissolving azo-isobutyric acid dinitrile in methylene chloride, adding p.v.c. powder, which is thereby swollen, and thereafter dried; (c) by mixing p.v.c. powder mechanically with azo-dicarboxylic acid amide to form a granulated material which is then reduced in a hammer-mill; (d) by mixing p.v.c. powder with dibutyl phthalate without causing gelation and then mechanically incorporating azo-isobutyric acid dinitrile. Other spraying mixtures mentioned include: polycaprolactam and dinitroso-pentamethylene diamine; polyvinylchloride and azo-butyric acid dinitrile or azo-hexahydrobenzene nitrile; polyethylene and benzene-1,3-disulphohydrazide; polyvinylacetate and azo-isobutyric acid dinitrile; and polyvinylchloride with a mixture of benzene-1,3-disulphohydrazide and azo-isobutyric acid dinitrile. Specification 840,663 is referred to.