Jsr Corporation

Katsuhiko Sakata

Osamu Ishikawa

Kunihiko Kobayashi

Nobuhiro Matsuda

Tsukasa Iwamoto

To provide a copolymer latex having a small particle size, which has a sufficient adhesion strength as a binder and a low viscosity and excellent handling properties in a composition containing a filler and the like, a composition for coating paper using the copolymer latex, and a coated paper having a coating layer formed by the composition. A copolymer latex contains a copolymer comprising: (A) 20 to 80% by mass of a structural unit derived from an aliphatic conjugated diene monomer, (B) 4 to 15% by mass of a structural unit derived from an unsaturated carboxylic acid monomer, and (C) 5 to 76% by mass of a structural unit derived from other copolymerizable monomer, wherein the total of (A), (B) and (C) being 100% by mass, and has a number average particle size of 30 to 80 nm by measurement with a transmission electron microscope, and has a viscosity of 50 to 400 mPa&#xb7;s at a solid content of 48% by mass.

Copolymer latex and composition containing the same and application product therof

An objective of the present invention is to provide an unsaturated nitrile-conjugated diene-typed rubber capable of giving a vulcanized rubber which exhibits is well-balanced in terms of the mechanical strength, the oil resistance and the like, as well as a process for the production of the same, and a rubber composition which is containing such rubber and exhibits an excellent processability as well as a process for the production of the same. The unsaturated nitrile-conjugated diene-typed rubber in the invention is produced by polymerizing using certain amounts of an olefinically unsaturated nitrile monomer such as acrylonitrile and a conjugated diene monomer such as butadiene at first, and continuing by supplying a remainder of the monomers at a certain ratio continuously or stepwise to proceed the polymerization. The unsaturated nitrile-conjugated diene-typed rubber is constituted 55 to 80 wt % of an olefinically unsaturated nitrile monomer unit as a repeating unit and 20 to 45 wt % of a conjugated diene monomer unit as a repeating unit based on 100 wt % of total of the monomer units. Glass transition temperature is &minus;15 to 30&deg; C. and the extrapolated temperature of the termination of the glass transition is preferably 70&deg; C. or less.

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Minato-ku, Japan

Katsuhiko Sakata