| abstract |
This nonaqueous secondary battery separator has a porous substrate, and, provided on one or both surfaces of the porous substrate, an adhesive porous layer which contains (1) a polyvinylidene fluoride resin (A) and (2) a polyvinylidene fluoride resin (B) described below and which has a porosity of 30-60% and an average pore diameter of 20-100nm.n(1) Polyvinylidene fluoride resin (A) is selected from a group consisting of vinylidene fluoride homopolymers and DVF copolymers which contain vinylidene fluoride (VDF)-derived structural units and hexafluoropropylene (HFP)-derived structural units, wherein the content of the HFP-derived structural units accounts for less than or equal to 1.5 mol% of all structural units.n(2) Polyvinylidene fluoride resin (B) is selected from VDF copolymers which contain VDF-derived structural units and HFP-derived structural units, wherein the content of HFP-derived structural units accounts for greater than 1.5 mol% of all structural units. |