Polarizing film, optical film laminate including polarizing film, and method for manufacturing the same

An optical film laminate comprising:

• a substrate comprising a crystallizable ester type thermoplastic resin in the form of a continuous web;
• and
• a polarizing film comprising a polyvinyl alcohol type resin formed on the substrate, said polarizing film including a dichroic material impregnated therein in a molecularly oriented state,
• wherein the polarizing film is formed by providing a laminate comprising a polyvinyl alcohol type resin layer formed on a substrate comprising a crystallizable ester type thermoplastic resin in an amorphous state and subjecting the laminate to a 2-stage stretching process comprising a preliminary in-air stretching and an in-boric-acid-solution stretching under a temperature in which the amorphous state of the substrate can be maintained, such that the polyvinyl alcohol type resin layer is stretched to a thickness of 10 μm or less, the polarizing film having optical properties which satisfy conditions represented by the formulae:
• P>−(100.929T-42.4−1)×100 (where T<42.3);
• and
• P≧99.9 (where T≧42.3)
• where:
• T represents a single layer transmittance and P a polarization rate.

A stretched laminate comprising a stretched intermediate consisting of a molecularly oriented polyvinyl alcohol type resin for manufacturing an optical film laminate, said stretched laminate comprising:

• a substrate comprising a crystallizable ester type thermoplastic resin in the form of a continuous web;
• and
• a polarizing film having a thickness of 10 μm or less, said polarizing film comprising a polyvinyl alcohol type resin formed on the a dichroic material impregnated therein in a molecularly oriented state,
• wherein the polarizing film has optical properties satisfying conditions represented by formulae:
• P>−(100.929T-42.4−1)×100 (where T<42.3);
• and
• P≧99.9 (where T≧42.3)
• where:
• T represents a single layer transmittance and P a polarization rate, and
• wherein said substrate comprising the a crystallizable ester type thermoplastic resin comprises a crystallizable polyethylene terephthalate subjected to a preliminarily in-air stretching under a temperature range maintaining an amorphous state thereof, and said polyvinyl alcohol type resin has an extent of crystallization in a range between 28% to 35% and an orientation function in a range between 0.15 and 0.35 is used.

A method for manufacturing an optical film laminate including a polarizing film comprising polyvinyl alcohol type resin having a dichroic material impregnated therein in a molecularly oriented state formed on a substrate comprising a crystallizable ester type thermoplastic resin in the form of a continuous web, comprising steps of:

• forming a stretched laminate comprising a stretched intermediate consisting of a molecularly oriented polyvinyl alcohol type resin by subjecting a laminate comprising the substrate comprising the crystallizable ester type thermoplastic resin in an amorphous state and a polyvinyl alcohol type resin layer formed on the substrate to a preliminary in-air stretching under a temperature maintaining the amorphous state of the substrate;
• forming a dyed laminate including a dyed intermediate comprising the polyvinyl alcohol type resin layer having the dichroic material impregnated therein in a molecularly oriented state by impregnating the dichroic material in the stretched laminate;
• and
• forming the optical film laminate including the polarizing film comprising the polyvinyl alcohol type resin having the dichroic material impregnated therein in a molecularly oriented state having a thickness of 10 μm or less by stretching the dyed laminate in boric acid solution.