| 摘要 |
1,133,980. Air-permeable polyvinyl chloride sheets. PELTEX. 31 Aug., 1966 [13 Sept., 1965], No. 38752/66. Headings C3C and C3P. Polyvinyl chloride sheets, which are highly permeable to air, are prepared by combining a process of mechanical foaming of a plastisol comprising plasticized polyvinyl chloride before spreading it out in a thin layer and a process of foaming by internal gaseous release from a porophoric agent in the course of the gelling of the said thin layer, which may be brought about by heating. A stabilizing surface-active agent may also be added to the initial paste, which can be considered as containing from 4 to 9À8 parts by weight of a mixture of a plastisol and a surface-active agent and from 0À2 to 6 parts by weight of a mixture of a plastisol and a porophoric agent. Inert charges and colouring agents may also be added. Suitable plasticizers are dioctyl phthalate, butylbenzyl phthalate, dibutyl phthalate, dioctyl azelate, polymer plasticizers, epoxidized plasticizers and epoxidized soya bean oil. Azodicarbonamide and azobisformamide are suitable as porophoric agents with, as accelerators of decomposition, organo-tin salts, compounds of lead, or alkaline earth salts. |
