Laminated body, separator, and nonaqueous secondary battery
A laminated body of the present invention includes: a porous film containing a polyolefin as a main component; and a porous layer on at least one surface of the porous film, the porous layer containing a resin, the laminated body satisfying 0≦(A)−(B)≦20 mN/m, where (A) represents the critical surface tension over the outermost surface of the porous layer, and (B) represents the critical surface tension that, in a case where the porous layer has been peeled from the laminated body at an interface with the porous film, the porous film has on the side of the interface.
1. A laminated body, comprising:
a porous film containing a polyolefin as a main component; and
a porous layer laminated on at least one surface of the porous film, the porous layer containing a resin,
the resin being a polyvinylidene fluoride-hexafluoropropylene copolymer,
the porous film having a thickness within a range of not less than 4 μm and not more than 17 μm,
the porous film having a weight per unit area within a range of not less than 5 g/m 2 and not more than 12 g/m 2 ,
the porous layer having a weight per unit area within a range of not less than 0.1 g/m 2 and not more than 5 g/m 2 ,
the laminated body satisfying Formula (1) below,
0 mN/m≦( A )−( B )≦20 mN/m (1),
where
(A) represents a critical surface tension over an outermost surface of the porous layer, and
(B) represents a critical surface tension that, in a case where the porous layer has been peeled from the laminated body at an interface with the porous film, the porous film has on a side of the interface,
the laminated body satisfying Formula (2) below,
( C )/( D )≦0.13 (2),
where
(C) represents an average pore diameter of the porous film, and
(D) represents a porosity of the porous film,
the average pore diameter (C) having a value in μm indicative of a mean value of respective sizes of pores in the porous film,
the porosity (D) having a value indicative of a volume proportion of void in the actual porous film with reference to a volume of the porous film assumed to have no void.
2. A separator for a nonaqueous electrolyte secondary battery,
the separator comprising
a laminated body according to claim 1 .
3. A nonaqueous electrolyte secondary battery, comprising
a separator according to claim 2 .