| 摘要 |
A non-aqueous secondary cell separator comprising a composite membrane provided with a porous substrate containing a thermoplastic resin and a heat-resistant porous layer provided on one side of the porous substrate, said porous layer containing an organic binder and an inorganic filler. The organic binder is a particulate polyvinylidene-fluoride resin. The heat-resistant porous layer has a porous structure in which the particulate polyvinylidene-fluoride resin and the inorganic filler are linked to each other. The thickness Ta of the heat-resistant porous layer and the thickness Tb of the composite membrane are present such that the ratio (Ta/Tb) is 0.10-0.40. The inorganic filler content of the heat-resistant porous layer is 85-99% by mass in relation to the total mass of the organic binder and the inorganic filler. The composite membrane has a longitudinal and lateral curl of 0.5 mm or less. |
