Composition for optical materials, process for production thereof, and optical materials made from the composition

Abstract

The present invention has an object of providing, for example, a composition for optical materials which contains a polythiol that can be predicted and assessed, in a stage prior to polymerization/curing, as being clouded or not clouded after polymerization/curing, and thus can be determined as being good or defective. According to the present invention, the above-described object is achieved by, for example, a composition for optical materials which comprises a polythiol that exhibits an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after the storage at 50° C. for 7 days, and an episulfide. Namely, an optical material made from a composition for optical materials which contains a polythiol satisfying the above turbidity requirements can be prevented from clouding to exhibit excellent transparency.

1 . A composition for an optical material comprising polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days, and episulfide. 
     
     
         2 . The composition for an optical material according to  claim 1 , further comprising sulfur. 
     
     
         3 . The composition for an optical material according to  claim 2 , wherein the episulfide and the sulfur are preliminarily polymerized. 
     
     
         4 . The composition for an optical material according to  claim 2 , wherein 10% or more of the sulfur is preliminarily polymerized with the episulfide. 
     
     
         5 . The composition for an optical material according to  claim 1 , for which degassing treatment has been conducted. 
     
     
         6 . An optical material obtained by polymerizing a composition for an optical material according to  claim 1 . 
     
     
         7 . The optical material according to  claim 6 , for which annealing treatment has been conducted after polymerizing the composition for an optical material. 
     
     
         8 . A method for producing a composition for an optical material, comprising the step of mixing polythiol having an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after being stored at 50° C. for 7 days, and episulfide. 
     
     
         9 . The method for producing a composition for an optical material according to  claim 8 , further comprising the step of incorporating sulfur. 
     
     
         10 . The method for producing a composition for an optical material according to  claim 8 , further comprising the step of degassing.