Abstract: The present invention relates to a polyimide copolymer used in a precursor of heat resistant adhesive and methods for preparing the same, and more particularly, to a polyamic acid copolymer and methods for preparing the same obtained by controlling a polymerization degree of the tetracarboxylic acid dianhydride and aromatic diamine. The present invention also comprises a polyimide copolymer obtained by curing the polyamic acid copolymer, and methods for preparing the same. The present invention also provides a heat resistant adhesive composition comprising the polyamic acid copolymer and the polyimide copolymer, and a semiconductor device using the same. The polyamic acid copolymer used in a precursor and polyimide copolymer obtained therefrom of the present invention has superior adhesion strength and simultaneously satisfies physical properties like high heat resistance and low water absorption rate, etc. and thus it can be effectively adhered parts of semiconductor devices, etc.

Abstract: The present invention provides a electrochemical element, wherein a multi-component composite film comprising a) polymer support layer film and b) a porous gellable polymer layer which is formed on either or both sides of the support layer film of a), wherein the support layer film of a) and the gellable polymer layer of b) are unified with each other without an interface between them.

Abstract: The present invention relates to a high crystalline polypropylene microporous membrane and a preparation method of the same, and it provides a preparation method of a polypropylene microporous membrane comprising the steps of preparing a precursor film using high crystalline polypropylene having a crystallinity of 50% or more and a very high isotacticity, annealing, stretching at a low temperature, stretching at a high temperature, and heat setting, and a polypropylene microporous membrane having superior permeability and mechanical properties prepared by the preparation method.

Abstract: The present invention provides a multi-component composite film comprising a) polymer support layer; and b) porous gellable polymer layer which is formed on one side or both sides of the support layer of a), wherein the support film of a) and the gellable polymer layer of b) are unified without the interface, a method for preparing the same, and a polymer electrolyte system applied the same.