GB546990A - Improvements in or relating to electric insulating materials - Google Patents

Abstract

546,990. Polyvinyl compositions. STANDARD TELEPHONES & CABLES, Ltd., SCOTT, T. R., and NEW, A. A. Jan. 2, 1941, Nos. 13609 [Divided out of 546,971] and 13610. [Class 2 (iii)] A process of preparing an electric insulating material from two different insulating materials, one of which is solid and consists of or comprises polystyrene and the other of which is liquid and consists of or comprises a plasticizer for polystyrene, comprises the steps of placing the solid material in a fragmentary state in a container not surrounding electrical apparatus and drawing the liquid into the container under vacuum at least to fill the interstices between the fragments of solid ; after restoring the pressure to atmospheric, the material may be allowed to stand, again evacuated, heated with or without stirring and the pressure then restored to atmospheric. The proportion of solid to liquid may be increased by using particles of solid of mixed grain size, by shaking the container and by compressing the particles ; the proportion of liquid to solid may be increased by preparing a solid material as set out above, comminuting the material, and repeating the process with the comminuted material and additional plasticizer. The polystyrene may be employed in admixture with rubber and the plasticizer may be poly α-methylstyrene, monostyrene, 1,1-di-p-tolylethane or a solution of polystyrene in monostyrene or 1,1-di-p-tolylethane. Specifications 504,765, 504,780, 532,687, [Group XXXVI], and 542,694, [Group XXVIII], are referred to. In Provisional Specification 546,990, [Group XXVIII], reference is made to Specification 540,300, [Group XXXVI]. According to Provisional Specification 546,990, any solid and any liquid insulating materials may be used.