Nippon Shokubai Co., Ltd.

Daisuke Imai

Tsuyoshi Hirata

Hiromichi Tanaka

Tsutomu Yuasa

Tomotaka Nishikawa

Hirokatsu Kawakami

Yoshitomo Nakata

Keiko Izumi

There is provided a vinylpyrrolidone-based copolymer having as essential components N-vinylpyrrolidone and hydroxyl group-containing (meth)acrylate, which gives a favorable crosslinked coating film, and a method for production by which the copolymer is easily obtained. A vinylpyrrolidone-based copolymer of the present invention contains a constitutional unit derived from N-vinylpyrrolidone and a constitutional unit derived from hydroxyl group-containing (meth)acrylate at a specific ratio, in which a K value according to Fikentscher is 12 or more, water insoluble matter is 0.5% by mass (on the basis of solid content) or less, and each content of iron, nickel, chromium, sodium and calcium is 500 ppb (on the basis of mass: the same hereinafter) or less, or electrical conductivity of a 10% by mass-aqueous solution of the vinylpyrrolidone-based copolymer is 35 &#x3bc;S/cm or less.

Vinylpyrrolidone-based copolymer and a method for production thereof

The admixtures for a cementitious composition of the invention, which have the above-mentioned constitutions, can suitably be used in cement pastes, mortar, concrete and like cement compositions and can stabilize the amount of air entrained with the lapse of time and thus facilitate the quality control of cement compositions and, further, can improve the workability of cement compositions owing to their excellent dispersing capacities. The cement compositions of the invention which comprise such admixture for a cementitious composition are excellent in water-reducing ability and workability and can give hardened products excellent in strength and durability and, further, can stably maintain the amount of air entrained without allowing increases in the amount of air even when the time of kneading is prolonged in the production.

Cement admixture and cement composition

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Suita, Japan

Daisuke Imai