Patent ID: 7651643

Claim:
A method of manufacturing polarizer, comprising the steps of: dyeing a polyvinyl alcohol-based film with iodine; uniaxially stretching the iodine-dyed polyvinyl alcohol-based film in an aqueous boric acid solution containing an iodide at a concentration of 4 to 12% by weight; and subsequently washing the film with an aqueous solution containing an iodide at a concentration of 0.8 to 2.5% by weight; wherein the resulting polarizer has a single transmittance of 43% or more, a polarizing efficiency of 99.9% or more, and a dichroic ratio of 30 or more, wherein the dichroic ratio is calculated from a parallel transmittance (Tp) and a crossed transmittance (Tc) at a wavelength of 440 nm according to the following formula: dichroic ratio={log 10 (1/ k 2 )}/{log 10 (1/ k 1 )}, where k 1 =½·√2×[( Tp+Tc ) 1/2 +( Tp−Tc ) 1/2 ] and k 2 =½·√2×[( Tp+Tc ) 1/2 −( Tp−Tc ) 1/2 ], and, an iodine content is of 1.5 to 2.5% by weight and a potassium content is of 0.2 to 0.6% by weight.