Abstract: Episulfide compounds useful as starting materials of optical materials are stably stored for a long period of time at a temperature ranging from their solidifying points to 20° C., preventing the production or precipitation of polymers and the yellowing.

Abstract: The episulfide compound of the present invention has, in one molecule, one or more epithio structures represented by the following Formula 1: 1

Abstract: A process for producing a resin having a large refractive index which comprises curing an episulfide compound having one or more epithio structures represented by formula (1) in one molecule by polymerization in the presence of a polymerization catalyst and 0.001 to 3.0 parts by weight of a phenol derivative per 100 parts by weight of the episulfide compound. (R1 represents a hydrocarbon group having 1 to 10 carbon atoms, R2, R3 and R4 each represents hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, Y represents S, O, Se or Te and m and n each represents 0 or 1).

Abstract: Optical materials which are cured compositions of a mixture of (a) a compound comprising sulfur and (b) an inorganic compound comprising at least one atom selected from the group consisting of sulfur atom and selenium atom, the optical material being obtained by curing the compositions by polymerization. Optical materials having a large refractive index and a large Abbe number are obtained from the compositions.

Abstract: A process for producing a lens comprising polymerizing bis(&bgr;-epithiopropyl)ether to form a lens.

Abstract: A composition comprising (a) 30 to 95% by weight of a compound having, in one molecule, one or more structures represented by the following formula (1): wherein R1 is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, R2, R3 and R4 are each hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, Y is O, S, Se or Te, m is an integer of 1 to 5 and n is an integer of 0 to 5; (b) 1 to 40% by weight of a compound having at least one group selected from the group consisting of isocyanate group and isothiocyanate group in one molecule; and (c) 1 to 50% by weight of a compound having at least one mercapto group in one molecule. A resin produced by curing the composition by polymerization has an excellent impact resistance and optical properties, and is suitable as an optical material.

Abstract: A process for tinting a resin for optical materials, the resin containing sulfur, includes dipping the resin for optical materials into a liquid containing an inorganic acid and/or an organic acid and thereafter tinting the resin. Where the organic acid is included in the liquid, the organic acid is a mixture of a first compound (I) having sulfo group and a second compound (II) having phenolic hydroxyl group but not having sulfo group, with a ratio (I)/(II) of the first compound to the second compound, in an amount by weight, being 0.01 to 2.0.

Abstract: An ether compound having a specific episulfide structure and a cured resin prepared by using this ether compound.

Abstract: A process for tinting a resin and a tinted optical material produced by the process. The process comprising dipping a resin into a liquid containing at least one compound selected from the group consisting of polar inorganic compounds and polar organic compounds and subsequently tinting the resin, wherein the resin is obtained by curing by polymerization of a sulfur-containing compound alone or a composition comprising the sulfur-containing compound, the sulfur-containing compound having in the molecule thereof one or more structures represented by the following formula hydrocarbon group having 1 to 10 carbon atoms, R2, R3 and R4 each represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, Y represents S or O and n represents 0 or 1.