Kuraray Co., Ltd.

Universitéde Liége

Kuraray Europe Gmbh

Yusuke Amano

Kazuhiko Maekawa

Yuki Tachibana

Keisuke Morikawa

Takumi Takayama

Yuki Shimizu

Naoki Fujiwara

Takuma Kaneshima

Masaki Kato

Tadahito Fukuhara

Katsuji Ujita

Tatsuya Tanida

Christophe Detrembleur

Jan Beekhuizen

Kensuke Nagashima

Christine Jerome

Keishi Hachiya

Antoine Debuigne

Naoyuki Iwachido

Yuki Kosaka

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

The present invention provides a dispersion stabilizer for suspension polymerization that, when used for suspension polymerization of a vinyl compound, provides excellent polymerization stability, and can produce a vinyl polymer having a reduced number of coarse particles, and a reduced number of fisheyes when molded into a sheet form. The present invention also provides a method therewith. The present invention relates to a dispersion stabilizer for suspension polymerization of a vinyl compound, the dispersion stabilizer comprising a vinyl alcohol polymer (A) having a viscosity-average degree of polymerization of more than 400 and less than 1,000, a degree of saponification of more than 67 mol % and less than 78 mol %, 0.02 mol % to 1.0 mol % of a group having an ethylenic double bond in its side chain, and an absorbance (x) at 280 nm of more than 0.17 and less than 0.65 in an ultraviolet absorption spectrum of a 0.1 mass % aqueous solution.

Dispersion stabilizer for suspension polymerization and method for producing vinyl polymer using same

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

Provided are graft copolymer particles enabling introduction of adsorptive functional groups adsorbing metals and others, a method for producing same, and an adsorbent using same. (1) Porous graft copolymer particles containing graft chains introduced into porous particles (particle surface having an average pore diameter of 0.01-50 &#x3bc;m) including at least one resin selected from olefin resins, water-insoluble modified polyvinyl alcohol resins, amide resins, cellulosic resins, chitosan resins and (meth)acrylate resins. (2) A method for producing porous graft copolymer particles including (I) melt-kneading a polymer A and a polymer B other than the polymer A to obtain a compound material, (II) extracting and removing the polymer B from the compound material to obtain a porous material of the polymer A, (III) granulating the porous material, and (IV) introducing graft chains into the porous particles. (3) An adsorbent of porous graft copolymer particles.

Porous graft copolymer particles, method for producing same, and adsorbent material using same

Provided are (1) a vinyl alcohol graft copolymer grafting polymerizable unsaturated monomers as a graft chain onto a side-chain mercapto group-containing vinyl alcohol polymer backbone, the graft chain being attached to the polymer backbone at a mercapto group, and the backbone including: a vinyl alcohol unit and a unit represented by the following formula (I): wherein Ris a hydrogen atom or a carboxyl group; Ris a hydrogen atom, a methyl group, a carboxyl group, or a carboxymethyl group; and X is a divalent Cgroup which contains a carbon atom and a hydrogen atom and may contain a nitrogen atom and/or an oxygen atom; and (2) an ion-exchange membrane having controlled swelling in water and excellent flex resistance, the membrane including a vinyl alcohol graft copolymer as described above.

Vinyl alcohol-based graft polymer, method for producing same, and ion-exchange membrane using same

Provided is a modified polyvinyl alcohol containing 0.1 to 10 mol % of a monomer unit represented by formula (1) below and having a degree of polymerization exceeding 2000. This provides a modified polyvinyl alcohol an aqueous solution of which foams less and which has excellent film strength and gas barrier properties under high humidity conditions, while having excellent water solubility. [In formula (), Rrepresents a hydrogen atom or a methyl group.]

Modified polyvinyl alcohol and production method therefor

The present invention provides a vinyl alcohol polymer having a mercapto group and having excellent reactivity. The present invention is a side-chain mercapto group-containing vinyl alcohol polymer including vinyl alcohol units and structural units represented by the following formula (I) (the characters in the formula are as defined in the description): 

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Kurashiki, Japan

Yusuke Amano