| 摘要 |
Tubular retainers for the active material of accumulator electrodes are made from polyvinyl chloride plasticized with polyblend and rendered porous by the process described in Specification 565,022. Polyblend is a mixture of colloidal polyvinyl chloride and the copolymer of butadiene and acrylonitrile, the mixture being fused by heat to produce a rubber-like plastic material which may contain from 55 per cent to 80 per cent of polyvinyl chloride. The final mixture from which the tubes are made may contain from 99 to 77.5 per cent of polyvinyl chloride and from 1 to 22.5 per cent of the nitrile rubber. The tubes are made by mixing the polyvinyl chloride and polyblend with maize starch and methyl cyclohexanone and heating the mixture to 100 DEG C. and then extruding it into tubular form and cutting it into the required lengths. The tubes are immersed in boiling water and then placed over glass mandrels and finally immersed in sulphuric acid which removes the starch and causes the tubes to shrink. They are then washed and treated with a wetting-out agent and dried. |
