Polaroid Corporation

Narendra S Kadaba

John J Cael

Giorgio B Trapani

Stewart Bennett

Lori P Shah

A method is provided for the manufacture of a polyvinylidene-based light polarizer (cf., a 'K Sheet'-type polarizer). In one embodiment, the polyvinylidene chromophore of said polarizer is produced by the acid catalyzed dehydration of an oriented polymeric starting material, the acid catalyst being introduced in the method as a bonding agent used to secure the starting material to a carrier web (or other supporting substrate). Advantages of the method include reduced frequency of 'streaking' and 'mottling'; good processing speed; and the ability to use a low acid concentration, resulting in a correspondingly low-corrosion processing environment.

Method for the manufacture of a light-polarizing polyvinylene sheet

This invention relates to a new and improved light-polarizing sheet comprising molecularly oriented polyvinyl alcohol containing an oriented block segments of polyvinylene and said polyvinyl alcohol. In particular, the polarizing sheet comprises a polyvinylalcohol/polyvinylene block copolymer material wherein the polyvinylene blocks thereof are formed by molecular dehydration of a sheet of polyvinylalcohol; said sheet of polyvinylalcohol/polyvinylene block copolymer material comprising a uniform distribution of light-polarizing molecules of polyvinylalcohol/polyvinylene block copolymer material varying in the length, n, of the conjugated repeating vinylene unit of the polyvinylene block of the copolymer throughout the range of from 2 to 24; the concentration of each of said polyvinylene blocks, as determined by the absorption of wavelengths ranging from 200 to 700 nm remaining relatively constant, the degree of orientation of said light-polarizing molecules, as measured by the spectral dichroic ratio, R.sub.D, of said blocks, increasing throughout said range with increasing length, n, of said polyvinylene blocks; said polyvinylene block concentration and said degree of orientation of said molecules imparting to said sheet a photopic dichroic ratio, R.sub.D, of at least approximately 45.

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Chestnut Hill, MA, United States of America

Narendra S Kadaba