Polarizing film, optical film laminate comprising polarizing film, and stretched laminate for manufacturing the same
A polarizing film includes a polyvinyl alcohol (PVA) type resin having a dichroic material impregnated therein. The polarizing film is formed by stretching the PVA type resin, such that the thickness of the polarizing film is decreased to 10 μm or less, and. The polarizing film has optical properties which satisfy conditions represented by formulae: P >−(10 0.929T-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. The polarizing film can be made by providing a laminate comprising a PVA type resin layer formed on a non-crystallizable ester type thermoplastic resin substrate.
1. A stretched laminate for manufacturing an optical film laminating including a polarizing film, said stretched laminate comprising:
a non-crystallizable ester type thermoplastic resin substrate and a layer of a polyvinyl alcohol type resin formed on the non-crystallizable ester type thermoplastic resin substrate,
said non-crystallizable ester type thermoplastic resin substrate comprises a preliminarily in-air stretched non-crystallizable polyethylene terephthalate having an orientation function of 0.10 or less, and
said polyvinyl alcohol type resin having a degree of crystallization in a range between 27% to 40% and an orientation function in a range between 0.05 and 0.35.
2. A stretched laminate as defined by claim 1 , wherein the non-crystallizable ester type thermoplastic resin substrate has a thickness which is at least 6.0 larger than a thickness of the polyvinyl alcohol type resin layer formed thereon.
3. A stretched laminate as defined by claim 1 , wherein the non-crystallizable ester type thermoplastic resin substrate is stretched under an elevated temperature stretching process, said resin being selected from the group including polyethylene terephthalate copolymerized with isophthalic acid, polyethylene terephthalate copolymerized with cyclohexanedimethanol, and non-crystallizable polyethylene terephthalate comprising another copolymerized polyethylene terephthalate.
4. A stretched laminate as defined by claim 1 , wherein the non-crystallizable ester type thermoplastic resin substrate comprises a transparent resin.