Mitsubishi Gas Chemical Company, Inc.

Atsuki Niimi

Motoharu Takeuchi

Hiroshi Horikoshi

Yuichi Yoshimura

Akikazu Amagai

Masaaki Takasuka

Nobuyuki Uemura

Masanori Shimuta

Katsuyuki Mizuno

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&#xb0; C., preventing the production or precipitation of polymers and the yellowing.

Method of storing episulfide compound

Process for producing a resin having a large refractive index

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.

Composition for optical materials

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

Process for producing a lens by polymerizing bis(&bgr;-epithiopropyl) ether

Composition for producing resin

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.

Process for tinting a resin for optical materials

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

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Tokyo, Japan

Atsuki Niimi