Kuraray Co., Ltd.

Universitéde Liége

Kuraray Noritake Dental Inc.

Nippon Mektron Limited

Kazuhiko Maekawa

Yusuke Amano

Yuki Tachibana

Takumi Takayama

Mamoru Omoda

Yuki Shimizu

Yukiatsu Komiya

Christophe Detrembleur

Mototsugu Yoshihara

Yukio Itoshima

Seiya Shimizu

Christine Jerome

Antoine Debuigne

Takashi Katayama

Toshiaki Sato

Kenji Suzuki

Kazushige Ishiura

Mitsuru Kato

Kenji Shachi

Hitoshi Nakatsuka

Naohiko Uchiumi

Shuhei Yorimitsu

Ichirou Inoue

Hiroshi Hayashihara

Shiroh Kishii

Masanari Uno

Hiroyuki Konishi

Hirofumi Tanabe

Hirotsugu Ida

Atsushi Itou

Shigeru Kawahara

Kazutoshi Mishima

Atsushi Itoh

Christine Jérôme

Yuki Kosaka

Mikiya Matsuura

Naoki Chikugo

Disclosed is a vinyl alcohol-based block copolymer that is a block copolymer composed of a vinyl alcohol-based polymer block (B-b) and a copolymer block (B-c) comprising a vinyl alcohol-based monomer unit and an acrylic acid-based monomer unit, wherein a content (Z) of the acrylic acid-based monomer unit relative to all monomer units is 0.05 to 20.0 mol %, the block copolymer has a saponification degree of 80 to 99.99 mol %, the block copolymer has a number-average molecular weight (Mn) of 20,000 to 440,000, the block copolymer has a molecular weight distribution (Mw/Mn) of 1.05 to 1.95, and a ratio (DP/DP) of a number-average polymerization degree (DP) of the vinyl alcohol-based polymer block (B-b) to the number-average polymerization degree (DP) of the block copolymer is 0.010 to 0.999. The copolymer has a fine balance derived from the copolymer block (B-c) of having a superior solubility in water while being unlikely to undergo thickening or gelation due to pH fluctuation, and also has high mechanic strength derived from the vinyl alcohol-based polymer block (B-b).

Vinyl alcohol-based block copolymer and method for producing same

A method of producing modified vinyl alcohol-based polymer particles, includes mixing vinyl alcohol-based polymer particles with a mixed medium containing unsaturated carboxylic acid, an acid catalyst, and water, wherein, by mixing the vinyl alcohol-based polymer particles with the mixed medium, the vinyl alcohol-based polymer particles are reacted with the unsaturated carboxylic acid to obtain modified vinyl alcohol-based polymer particles containing a vinyl ester unit represented by a formula (2) below, having a vinyl alcohol unit content based on the total constitutional units from 95 to 99.99 mol %, and having an average particle diameter from 50 to 2000 μm. The production method does not cause the problem of the residual sulfur content derived from a liquid medium used for reaction and is also capable of modifying the vinyl alcohol-based polymer particles while maintaining the particle shape.

Production method for modified vinyl alcohol-based polymer particles and particles obtained using same

A method of producing modified vinyl alcohol-based polymer particles, includes mixing vinyl alcohol-based polymer particles with a mixed medium containing unsaturated carboxylic acid, an acid catalyst, and water, wherein, by mixing the vinyl alcohol-based polymer particles with the mixed medium, the vinyl alcohol-based polymer particles are reacted with the unsaturated carboxylic acid to obtain modified vinyl alcohol-based polymer particles containing a vinyl ester unit represented by a formula (2) below, having a vinyl alcohol unit content based on the total constitutional units of 60 mol % or more and less than 95 mol %, and having an average particle diameter from 50 to 2000 μm. The production method is capable of controlling the particle shape and does not cause the problem of the residual sulfur content, and is further convenient and economically advantageous.

Production method for modified vinyl alcohol polymer particle and particle obtained thereby

The invention relates to particles with an average particle size of 300 to 1000 &#x3bc;m, comprising a modified polyvinyl alcohol having vinyl alcohol units and structural units represented by formula (1), wherein a content of the vinyl alcohol units is 60 to 90 mol % based on the total structural units: 

Particles containing modified polyvinyl alcohol

A polyvinyl alcohol has a number-average molecular weight (Mn) from 4,400 to 440,000, a molecular weight distribution (Mw/Mn) from 1.05 to 1.70, a degree of saponification from 80 to 99.99 mol %, wherein the polyvinyl alcohol contains an end group represented by a formula (I) below, and a molar ratio (X) of the end group based on total monomer units and the number-average molecular weight (Mn) satisfy a formula (1) below. Such a polyvinyl alcohol has a narrow molecular weight distribution and a high number-average molecular weight with hue good. (In the formula, Rdenotes an optionally substituted aromatic group having a carbon number from 6 to 20, and Rdenotes a hydrogen atom, an alkyl group having a carbon number from 1 to 20, or an optionally substituted aromatic group having a carbon number from 6 to 20.)X&#xb7;Mn/44&#x2265;0.5&#x2003;&#x2003;(1)

Polyvinyl alcohol and method for producing polyvinyl alcohol

A polyvinyl alcohol has a number-average molecular weight (Mn) from 4,400 to 440,000, a molecular weight distribution (Mw/Mn) from 1.05 to 1.70, a degree of saponification from 80 to 99.99 mol %, and a carbon-carbon double bond content (X) of 0.1 mol % or less based on total monomer units, and satisfying a formula (1) below. A polyvinyl alcohol, having a narrow molecular weight distribution and a high number-average molecular weight with good hue, and a method for producing the same are thus provided.X&#xb7;Mn&#x2264;1000&#x2003;&#x2003;(1)

Polyvinyl alcohol

There is provided a vinyl alcohol-based polymer having an olefin in side chain, comprising 0.001 to 10 mol % of a structural unit represented by Formula (1) based on the total amount of structural units, wherein the total carbon number of X, R, R, Rand Ris 2 or more. The vinyl alcohol-based polymer having an olefin in side chain has excellent storage stability, good solubility in water or an organic solvent even after thermal treatment, and excellent reactivity to high energy beam. In Formula (1), X represents an optionally substituted divalent aliphatic hydrocarbon group, an optionally substituted divalent alicyclic hydrocarbon group, an optionally substituted divalent aromatic hydrocarbon group, or a group consisting of two or more of these groups which are linked via at least one bond selected from the group consisting of an amide bond, an ester bond, an ether bond, and a sulfide bond; R, R, Rand R, independently of each other, represents a hydrogen atom, an optionally substituted aliphatic hydrocarbon group, an optionally substituted alicyclic hydrocarbon group, or an optionally substituted aromatic hydrocarbon group; and X, R, R, Rand Rcan be arbitrarily combined to form a ring structure). 

Vinyl alcohol-based polymer having olefin in side chain

The present invention relates to a vinyl alcohol-based polymer having an olefin in side chain, comprising a vinyl alcohol unit and a structural unit represented by Formula (I), wherein X represents a divalent saturated hydrocarbon group with 1 to 6 carbon atoms, optionally having a branched structure; Y represents a hydrogen atom or a saturated hydrocarbon group with 1 to 6 carbon atoms, optionally having a branched structure; and Z represents a hydrogen atom or a methyl group. Thus, there is provided a vinyl alcohol-based polymer having an olefin in side chain exhibiting higher water solubility even after thermal treatment, higher storage stability, and higher reactivity to high energy beam, and a method for producing it. 

Side-chain-olefin-containing vinyl alcohol polymer and method of producing same

A polyvinyl alcohol is produced in a method comprising: a polymerization step comprising polymerizing vinyl ester monomers by controlled radical polymerization in the presence of a radical initiator and an organic cobalt complex to obtain a polymer solution containing a polyvinyl ester; an extraction step comprising extracting a cobalt complex from the polymer solution by contacting an aqueous solution containing a water-soluble ligand with the polymer solution; and a saponification step comprising saponifying the polyvinyl ester after the extraction step to obtain a polyvinyl alcohol. A method for producing a polyvinyl alcohol is thus provided that has a narrow molecular weight distribution and a high number-average molecular weight with good hue and further good solubility in water.

Polyvinyl alcohol and method for producing same

The present invention provides a dental polymerizable composition that requires less discharging force, is easily formable, has low polymerization shrinkage stress during curing, and exhibits high stain resistance and surface gloss when cured. The present invention relates to a dental polymerizable composition including a (meth)acrylic block copolymer (A), a polymerizable monomer (B), and a polymerization initiator (C). The (meth)acrylic block copolymer (A) consists of a (meth)acrylic polymer block (a) having a curable functional group and a (meth)acrylic polymer block (b) having no curable functional group. The curable functional group has a partial structure represented by the following general formula (1): 

Dental polymerizable composition

A method for producing a (meth)acrylate copolymer via anionic polymerization of a mixture of a di(meth)acrylate and an alkyl (meth)acrylate in the presence of an organolithium compound, a tertiary organoaluminum compound, and at least one Lewis base selected from ethers and tertiary polyamines. The (meth)acrylate copolymer produced has a (meth)acryloyl groups in a side chain.

Method for producing (meth)acrylate copolymer

The invention provides an aqueous dispersion which includes i) an aqueous dispersion (I) resulting from dispersion of a block copolymer (I) composed of at least one polymer block (A) containing olefin monomer units and at least one polymer block (B) containing 2 to 100 mole percent of units derived from at least one vinyl monomer having a carboxyl or carboxylic anhydride group and 98 to 0 (zero) mole percent of units derived from another vinyl monomer or monomers copolymerizable with the carboxyl group- or carboxylic anhydride group-containing vinyl monomer, in an aqueous solution of not less than 0.05 equivalent, relative to the carboxyl or carboxylic anhydride group, of a basic substance, and ii) a polyurethane (II), iii) vinyl polymer (III) or iv) tackifier (IV) incorporated in the aqueous dispersion (I). The aqueous dispersion of the invention has excellent adhesiveness to various substrates and stability, and gives a coating layer having excellent weather resistance, water resistance and resistance to solvent attack. The aqueous dispersion of the invention is particularly useful as a coating composition and/or a primer.

Aqueous dispersion

Light-weight fiber excellent in dyeability

The invention is to provide an aqueous dispersion having good adhesiveness, especially airtight adhesiveness to various substrates, and having good storage stability, good weather resistance and good hydrophobicity. The aqueous dispersion comprises a block copolymer composed of polymer blocks (A) consisting essentially of olefin monomer units and polymer blocks (B) comprising from 2 to 100 mol % of units of vinyl monomers having a carboxyl group or a carboxylic acid anhydride group and from 0 to 98 mol % of units of other vinyl comonomers capable of copolymerizing with the vinyl monomers, dispersed in an aqueous solution of at least 0.05 equivalents, relative to the carboxyl group or the carboxylic acid anhydride group, of a basic substance.

Aqueous dispersion and process for producing the same

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Kurashiki, Japan

Kazuhiko Maekawa