Resin composition for sealant layer of battery packaging material
A resin composition can impart high insulating properties, sealing properties, and moldability to a battery packaging material. A resin composition minimizes cracks when used in the sealant layer of a battery packaging material and a heat seal section of the material is bent, and can impart high insulating properties. A resin composition for use in the sealant layer of a battery packaging material contains: at least one of a propylene-ethylene random copolymer having a melting point of 156° C. or more and an ethylene content of 5 mass % or less and a propylene-ethylene block copolymer having a melting point of 158° C. or more and an ethylene content of 7 mass % or less; and a polyolefin elastomer having a melting point of 135° C. or more. A resin composition for the sealing layer of a battery packaging material contains a polyolefin resin having an isotactic fraction of 99% or less.
1. A resin film for a sealant layer of a battery packaging material, the resin film being formed of a resin composition comprising a polyolefin-based resin having (i) an isotactic fraction (mm) in the range of 90% to 95%, and (ii) a melting point in the range of from 110 to 160° C., wherein the resin film has a thickness of 40 μm or less.
2. The resin film according to claim 1 , wherein the polyolefin-based resin has an ethylene unit content of 0.1 to 10 mol %.
3. The resin film according to claim 1 , wherein in the polyolefin-based resin, an amount of components soluble in n-decane at 80° C. is 0.1 to 15% by mass.
4. The resin film according to claim 1 , wherein the polyolefin-based resin includes at least propylene as a constituent monomer.
5. A battery packaging material comprising a laminate in which at least a base material layer, a metal layer and a sealant layer are laminated in this order, wherein:
the sealant layer includes a layer formed of a resin composition comprising a polyolefin-based resin having an isotactic fraction (mm) in the range of 90% to 95%, and
a melting point T m1 of the layer formed of the resin composition is in the range of from 100 to 160° C.
6. The battery packaging material according to claim 5 , wherein the layer formed of the resin composition has a thickness of 1 to 20 μm.
7. The battery packaging material according to claim 5 , wherein the sealant layer has a thickness of 40 μm or less.
8. A battery, wherein a battery element including a positive electrode, a negative electrode and an electrolyte is sealed in the battery packaging material according to claim 5 .
9. The resin film according to claim 1 , wherein in the polyolefin-based resin, an amount of components soluble in n-decane at 80° C. is 0.1 to 5% by mass.
10. The battery packaging material according to claim 5 , wherein in the polyolefin-based resin, an amount of components soluble in n-decane at 80° C. is 0.1 to 5% by mass.
11. The resin film according to claim 1 , having a thickness of 1 to 20 μm.