| abstract |
The episulfide compound of the present invention has, in one molecule, one or more epithio structures represented by the following Formula 1: <CHEM> wherein R<1> is C1-C10 hydrocarbylene group; R<2>, R<3> and R<4> are each independently C1-C10 hydrocarbyl group or hydrogen; Y is S, O, Se or Te; n is an integer of from 0 to 5; and m is 0 or 1, and further characterized by having a nitrogen content of 5000 ppm or less. The optical material produced by curing the episulfide compound by polymerization has a high refractive index and a large Abbe's number with little coloring and haze. The optical material is useful, particularly, as spectacle plastic lenses. |