Separator for non-aqueous secondary battery, non-aqueous secondary battery, and method of manufacturing non-aqueous secondary battery

A separator for a non-aqueous secondary battery, comprising:

• a porous substrate;
• and
• a porous layer formed on one surface or both surfaces of the porous substrate and containing a polyvinylidene fluoride type resin and a filler, wherein:
• the filler is selected from the group consisting of metal hydroxides, metal oxides and metal sulfates,
• a content of the filler in the porous layer is from 30% by mass to 80% by mass with respect to a total mass of the polyvinylidene fluoride type resin and the filler,
• a thermal shrinkage ratio in a machine direction of the separator when heat-treated at 135° C. for 30 minutes is 20% or less, and
• the polyvinylidene fluoride type resin contains the following resin A or resin B:
• resin A:
• a copolymer containing a vinylidene fluoride monomer unit and a hexafluoropropylene monomer unit and having a weight average molecular weight of from 100,000 to 350,000, wherein a content of the hexafluoropropylene monomer unit is more than 5% by mass but not more than 10.0% by mass with respect to all monomer units of resin A;
• resin B:
• a copolymer containing a vinylidene fluoride monomer unit and a hexafluoropropylene monomer unit and having a weight average molecular weight of from hexafluoropropylene monomer unit and having a weight average molecular weight of from 100,000 to 1,000,000, wherein a content of the hexafluoropropylene monomer unit is from 11.5% by mass to 15% by mass with respect to all monomer units of resin B.