Patent ID: 8404066

Claim:
A method for manufacturing a thin high-performance polarizing film having a thickness of 7 μm or less and comprising a polyvinyl alcohol type resin having a dichroic material impregnated therein in a molecularly oriented state, the method comprising steps of: coating a polyvinyl alcohol type resin on a resin substrate having a thickness of at least 20 μm and then drying the polyvinyl alcohol type resin to thereby form a polyvinyl alcohol type resin layer on said resin substrate; immersing thus produced polyvinyl alcohol type resin layer in a dyeing solution of a dichroic material to thereby impregnate the dichroic material in the polyvinyl alcohol type resin layer; and following the immersing step stretching the polyvinyl alcohol type resin layer having the dichroic material impregnated therein together with the resin substrate in a boric acid solution under a temperature not higher than 65° C. such that a total stretching ratio of 5.0 or more with respect to an original length is achieved.