GB753879A - Improvements in and relating to cellular compositions - Google Patents

Abstract

Synthetic rubbers or resins are given a cellular structure of substantially uniform cell size by intimately dispersing in the material, when in an uncured or unfluxed state, an N-nitroso-N-alkyl or N-nitroso-N-aralkyl amide of an aromatic carboxylic acid and then heating the composition to decompose the amide blowing agent. Amides suitable for the purpose are: N,N1 - dinitroso - N,N1 - dimethyl terephthalamide, N,N1 - dinitroso - N,N1 - dimethyl isophthalamide, N,N1 - dinitroso - N,N1 - diethyl terephthalamide, N - nitroso - N - methyl - p - tert-butyl benzamide, N,N1-dinitroso-ethylene dibenzamide, N,N1 - dinitroso - tetramethylene dibenzamide, N,N1 - dinitroso - N,N1 - dimethyl phthalamide, p,p1 - bis - (N - nitroso - N - methyl benzamide), N - nitroso - N - benzyl benzamide, N,N1 - dinitroso - hexamethylene dibenzamide, N,N1 - dinitroso - ethylene - bis - p - methoxybenzamide. Specified synthetic rubbers and resins are butadiene-styrene copolymer, polychloroprene, polyvinyl chloride and vinyl chloride-acetate copolymer. The quantity of amide is preferably 1-15 parts per 100 parts of synthetic rubber and 2-45 parts per 100 parts of resin.ALSO:Natural and synthetic rubbers, and organic materials other than elastomers which can be shaped when soft and hardened afterwards, are given a cellular structure of substantially uniform cell size by intimately dispersing in the material, when in an uncured or unfluxed state, an N - nitroso - N - alkyl or N - nitroso - N - aralkyl amide of an aromatic carboxylic acid and then heating the composition to decompose the amide blowing agent. Amides suitable for the purpose are: N, N1 - dinitroso - N, N1 - dimethyl terephthalamide; N, N1 - dinitroso - N, N1 - dimethyl isophthalamide; N, N1 - dinitroso - N, N1 - diethyl terephthalamide; N - nitroso - N - methyl - p - ter - butyl benzamide; N, N1 - dinitroso - ethylene dibenzamide; N, N1 - dinitroso - tetramethylene dibenzamide; N, N1 - dinitroso - N, N1 - dimethyl phthalamide; p, p1 - bis - (N - nitroso - N - methyl benzamide); N - nitroso - N - benzyl benzamide; N, N1 - dinitroso - hexamethylene dibenzamide; N, N1 - dinitroso - ethylene - bis - p - methoxybenzamide. Examples are given of the use of the first six of these amides in rubber, synthetic rubber and synthetic resin compositions. The quantity of amide is preferably 1-15 parts per 100 parts of rubber and 2-45 parts per 100 parts of resin. Variations in density or stiffness of the cellular products may be achieved by altering the proportions of the ingredients used.