Shin-etsu Chemical Co., Ltd.

Takeda Chemical Industries, Inc.

Masatoshi Asano

Shouhei Kozakai

Takashi Uemura

Kyuya Yamazaki

Mitsuhiro Nishimura

Akira Yamamoto

Kazuaki Sumita

Toshio Ohba

Shigeru Konishi

Kaoru Katoh

A liquid epoxy resin composition comprising: (A) a liquid epoxy resin; (B) an amine type curing agent; (C) a sulfur-containing phenol compound in an amount of from 1 to 20 parts by weight per total 100 parts by weight of the components (A) and (B); and (D) an inorganic filler in an amount of from 50 to 900 parts by weight per 100 parts by weight of the component (A).

Liquid epoxy resin composition

In a coated optical fiber comprising a quartz glass fiber, a primary coating and a secondary coating, the secondary coating is formed by curing a resin composition comprising (A) 20-90 wt % of a polyurethane (meth)acrylate oligomer which is synthesized from an alicyclic polyisocyanate, contains 5-90 wt % of a polyurethane (meth)acrylate oligomer having a Mn of up to 1,000, and has an overall Mn of up to 10,000, and (B) 80-10 wt % of an ethylenically unsaturated compound, with electron beams accelerated at 50-125 kV. The coated optical fiber has a minimized transmission loss.

Coated optical fiber

The invention provides a photocurable resin composition which inhibits the deactivation of a bisacylphosphine oxide-series photopolymerization initiator and is useful for coating optical fibers. The photocurable resin composition comprises (A) a polyurethane (meth)acrylate oligomer, (B) an ethylenically unsaturated compound, (C) a bisacylphosphine oxide-series photopolymerization initiator, and (D) a tertiary amine and no tin component. Incorporation of the component (D) inhibits the decomposition and deactivation of the component (C). The component (A) may contain an aliphatic C.sub.14-40 polyol (hydrogenated dimerdiol, 12-hydroxystearyl alcohol) as a polyol component. This resin composition is used for a primary coating of a glass fiber or an indirect coating of an optical fiber through the primary layer, the coating layer being cured by light irradiation to provide an optical fiber coated with the resin composition.

Photocurable resin composition and a method for producing the same

In the coating composition for a optical fiber of the present invention, a polyurethane (meth)acrylate oligomer (A), which is based on a urethane prepolymer having an equivalent ratio of NCO group in a polyisocyanate (a) to OH group in a polyol (b) of more than 3.0, is used and the oligomer (A) has a mixing weight ratio of an oligomer (d) having a number average molecular weight of 800 or less to an oligomer (e) having a number average molecular weight of 1,000 or more of 30/70-70/30. The coating composition of this invention has a low viscosity, and therefore, is suitable for a rapid fiber-drawing in a production of an optical fiber. Further, a cured material obtained from the coating composition of the present invention has both a high elastic modulus and a high elongation, which properties are required for a hard material, and has a slight change of elastic modulus with a change of temperature to improve a long-term reliability of an optical fiber.

Coating composition for optical fiber

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Annaka, Japan

Masatoshi Asano