| 摘要 |
<p>Microporous material is made by (a) prepg. a uniformly-dispersed mixt. of rigid PVC, organic solvent and extractable filler with near particle size 5-200 mum; (b) shaping the mixt. (usually into sheet); (c) coagulating the PVC with a mixt. of solvent and non-solvent for the PVC which is at least partially miscible with the solvent used in (a) and opt. contains dissolved filler as in (a), and (d) simultaneously or subsequently extracting virtually all the filler. Wt. ratio of solvent to polymer in (a) is 2-7:1 and wt. ratio of filler to polymer is 6.5-20:1. Compsn. of the mixt. lies within the specified points on a graph. Used esp. as battery separators. Use of rigid PVC as polymer, high filler addns., and solvent/nonsolvent mixts. for coagulation gives materials with increased porosity and permeability, and lower average pore size, free from damaged pore structure.</p> |
