GB745248A - Process for the production of closed-cell gas-containing cellular bodies - Google Patents

Abstract

Closed-cell, gas-containing cellular bodies are made by forming a pasty liquid from a thermoplastic resin or an elastomer, e.g. polyvinyl chloride, or copolymers of vinyl chloride with vinyl acetate or acrylonitrile or both or with acrylic esters, polystyrene, polyacrylic compounds, cellulose acetate, or a mixture of polyvinyl chloride and an acrylonitrile-butadiene polymerizate, bringing the liquid in a shape having a surface contact area several times larger than a sphere of the same mass into contact in a container under pressure, e.g. 30-350 atmospheres, with a difficulty condensable gas, e.g. nitrogen, hydrogen or carbon dioxide, introduced from outside the container, so as to incorporate and distribute the gas uniformly in the liquid, heating before, during or after incorporation of the gas so as to gelatinize any ungelatinized material, cooling, relieving the pressure on the gas-treated material, removing the rudimentary cellular body so produced from the container and expanding it. Conversion of the starting material to the pasty liquid condition may be effected by addition of solvents or plasticizers, or by heating.ALSO:Closed-cell, gas-containing cellular bodies are made by forming a pasty liquid from a natural or artificial rubber or a thermoplastic resin, or a mixture, e.g. polyvinyl chloride with an acrylonitrile-butadiene polymerizate, bringing the liquid in a shape having a surface contact area several times larger than a sphere of the same mass into contact in a container under pressure, e.g. 30-350 atmospheres, with a difficulty condensable gas, e.g. nitrogen, hydrogen or carbon dioxide, introduced from outside the container, so as to uniformly incorporate and distribute the gas in the liquid, heating before, during or after incorporation of the gas, so as to gelatinize any ungelatinized starting material, cooling, relieving the pressure on the gas-treated material, removing the rudimentary cellular body so produced from the container and expanding it. Conversion of the starting material to the pasty liquid condition may be effected by addition of solvents or plasticizers, or by heating. Incorporation of the gas may be effected by rolling the liquid around in a rotary container under pressure of the gas, by stirring, kneading or screw-conveying the liquid in a stationary container under pressure of the gas, or by passing the liquid, more than once if desired, as drops, threads or sheets through a container of the gas under pressure. The successive treatments may be carried out in one container, or the material may be pumped, screw-conveyed, or expelled by increased pressure of gas from one container to another.