CARBONATE CRYSTAL, MANUFACTURING METHOD THEREOF, AND TRANSPARENT OPTICAL RESIN COMPOSITION

摘要

The object of the present invention is to provide a carbonate crystal, which has oriented birefringence, is needle- or rod-like, and is able to negate the birefringence without sacrificing the light transmittance of a transparent polymeric resin when it exists in the transparent resin; a manufacturing method of the carbonate crystal; and a transparent optical resin composition comprising the carbonate resin. The carbonate crystal has an aspect ratio of two or greater, the average major axis length of 400 nm or shorter, and the variation coefficient expressed in Formula (1) below is 0.40 or less: Formula (1) wherein r denotes an average major axis length, n denotes the number of particles used for the measurement of the major axis length, and n denotes the major axis length of the ith particle measured.