Patent ID: 8211568

Claim:
A packaging material for a flat electrochemical cell comprising at least a base material layer, a metal foil layer having a chemical conversion treated layer on at least one surface thereof, an acid-modified polyolefin layer and a thermally adhesive resin layer laminated in this order, wherein the acid-modified polyolefin layer is a resin layer constituted of an acid-modified polyolefin based resin, the thermally adhesive resin layer has a resin layer constituted of a propylene based resin, a propylene based elastomer resin is mixed in at least one of the acid-modified polyolefin based resin and the propylene based resin, the propylene based elastomer resin has a network structure in which islands constituting a crystal area are communication with each other, thereby covering a whole of an amorphous area; and the propylene based elastomer resin is a copolymer composed of a constitutional unit derived from propylene and a constitutional unit derived from an α-olefin having from 2 to 20 carbon atoms except propylene; when the total sum of the constitutional unit derived from propylene and the constitutional unit derived from an α-olefin is defined as 100% by mole, contains 50% by mole or more of the constitutional unit derived from propylene; and is satisfied with the following physical properties: (a) a Shore A hardness (ASTM D2240) is in the range of from 65 to 90, (b) a melting point is in the range of from 130° C. to 170° C., (c) a density (ASTM D1505) is in the range of from 860 to 875 kg/m 3 , and (d) a glass transition temperature as measured by DSC is in the range of from −25° C. to −35° C.