Kuraray Co., Ltd.

Ken Yuki

Toshiaki Sato

Hitoshi Maruyama

Takuji Okaya

Masato Nakamae

Junnosuke Yamauchi

Naoki Fujiwara

Hirotoshi Miyazaki

Taku Tanaka

Akio Mizobe

Shigeki Takada

Kazutoshi Terada

Kenji Saimen

Tatsuaki Hattori

Sotaro Itadani

Kazunari Igarashi

Daisuke Miyake

The present invention relates to an aqueous emulsion comprising a dispersant of a modified polyvinyl alcohol with an ethylene unit content of 2 to 9 mol % and a degree of hydrolysis of at least 95 mol %, a dispersoid of a polymer of an ethylenically unsaturated monomer, and a ratio (.eta.2 rpm/.eta.20 rpm) of Brookfield viscosity at 30.degree. C., 2 rpm (.eta.2 rpm) as against Brookfield viscosity at 30.degree. C., 20 rpm (.eta.20 rpm) being 1 to 1.8 when the latter viscosity (.eta.20 rpm) is adjusted to 5,000 to 10,000 mPa.multidot.S. The aqueous emulsion according to the present invention is excellent in structural viscosity (flowability, high speed application performance), provides coated layers with high water resistance and low-temperature stability, and can be suitably used extensively as an adhesive for paper, wood and plastics, as a binder for impregnated paper and non-woven products, as an additive for mortar, as a paint, and in paper and fiber processings.

Aqueous emulsion

Process for producing polyvinyl ester having a high degree of polymerization and an intrinsic viscosity of from 15 dl g.sup.-1 to 3.2 dl g.sup.-1, and a polyvinyl ester obtained thereby. The process comprises subjecting a vinyl ester monomer to emulsion polymerization using nonionic emulsifiers nonionic-anionic emulsifiers, or anionic emulsifiers and a redox initiator at a temperature of -60.degree. to 15.degree. C.

Process for producing polyvinyl ester having a high degree of

There is disclosed an emulsion composition which comprises an aqueous emulsion (A) obtained by emulsion polymerization of 100 parts by weight of an ethylenically unsaturated monomer in the presence of 1 to 15 parts by weight of a carboxyl group-modified polyvinyl alcohol such as itaconic acid-modified polyvinyl alcohol as the dispersant and a polyamide resin (B) such as polyamide epichlorohydrin. The above emulsion composition has a long pot-life and can easily be made into a film having a high wet strength and being excellent in water resistance, hot water resistance and heat resistance. Accordingly, it can effectively be utilized in a variety of applications including paint coating, adhesive, fiber sizing agent and paper coating.

Emulsion composition

Process for suspension polymerization of vinyl compound

Disclosed herein is a new process for producing polyvinyl ester having a high degree of polymerization having an intrinsic viscosity not less than 1.5 dl/g, preferably not less than 2.2 dl/g, and most preferably higher than 3.2 dl/g, said process comprising subjecting vinyl ester monomer to low-temperature emulsion polymerization under specific conditions. Disclosed also herein is a new process for producing polyvinyl alcohol having a high degree of polymerization having an intrinsic viscosity not less than 1.5 dl/g, preferably not less than 2.2 dl/g, and most preferably higher than 3.2 dl/g, said process comprising saponifying in the usual way the polyvinyl ester obtained by low-temperature emulsion polymerization under specific conditions.

There is disclosed a composition which comprises an aqueous emulsion selected from (A-1) aqueous emulsion comprising a dispersoid which comprises a vinyl ester polymer (1) and a copolymer a (meth)acrylic ester and a primary hydroxyl group-containing ethylenically unsaturated monomer (2), the polymer (1) being present principally in the central part of the dispersoid, the copolymer (2) having a glass transition temperature of lower than 50.degree. C. an being present principally in the peripheral part thereof; and a dispersant comprising a vinyl alcohol polymer and (A-2) aqueous emulsion comprising a dispersoid which comprises a copolymer of a hydrophobic unsaturated monomer such as (meth)acrylic ester and a primary hydroxyl group-containing ethylenically unsaturated monomer; and a dispersant comprising a vinyl alcohol polymer having a mercapto group at an end thereof and a (B) polyvalent isocyanate compound. Disclosed also are an adhesive comprising the aforementioned composition and a wooden product which is joined by the use of the adhesive. The above-disclosed adhesive is excellent in initial adhesivity, adhesive strength, water resistance and so forth.

Composition, adhesive and aqueous emulsion

Provided is a process for producing molded articles having excellent flexural strength, flexibility and dimensional stability, which comprises autoclave-curing at not lower than 100.degree. C. an aqueous composition comprising a hydraulic material (A) and a polyvinyl alcohol (B) powder, said polyvinyl alcohol (B) powder being contained in an amount of 0.1 to 20% by weight based on the weight of said hydraulic material (A). Also provided are molded articles comprising a hydraulic material (A) and a polyvinyl alcohol (B), said polyvinyl alcohol (B) being contained in an amount of 0.1 to 20% by weight based on the weight of said hydraulic material (A), said molded article having a structure comprising said polyvinyl alcohol (B) having once dissolved and then solidified being dispersed therein in the form of islands. These molded articles have excellent flexural strength, flexibility and dimensional stability.

Process for producing molded articles

Growing community of inventors

Kurashiki, Japan

Ken Yuki