Kuraray Co., Ltd.

Kazuyuki Somemiya

Naoki Fujiwara

Masaki Kato

Takeshi Kusudou

Takanori Isozaki

Yasuhiro Nonaka

Shintaro Hikasa

Masako Katayama

Yoko Nakano

Yoshikazu Yamasaki

Syunji Tago

Yoshiko Sho, Legal Representative

Yukiko Sho, Legal Representative

Naoto Nishida

A method of continuously producing an ethylene-vinyl acetate copolymer in a polymerization vessel containing a reaction liquid containing ethylene, vinyl acetate, a polymerization initiator and methanol, the polymerization vessel being connected via piping to a heat exchanger circulating a coolant, the method includes the steps of: supplying ethylene, the polymerization initiator and methanol to the polymerization vessel; introducing pressurized gas containing ethylene present in a gas phase portion of the polymerization vessel into the heat exchanger; supplying vinyl acetate cooled to between &#x2212;50&#xb0; C. and 23&#xb0; C. to an upper portion of the heat exchanger; flowing vinyl acetate down in the heat exchanger while absorbing ethylene; letting vinyl acetate dissolving ethylene out of a bottom portion of the heat exchanger and adding to the reaction liquid in the polymerization vessel; and taking the reaction liquid out of the polymerization vessel. This provides a method of efficiently removing heat during polymerization of an ethylene-vinyl acetate copolymer.

Method for producing ethylene-vinyl acetate copolymer

An object of the present invention is to provide an EVOH-containing resin composition which has superior appearance characteristics and long-run workability in melt molding and enables occurrence of yellowing etc., in melt molding to be inhibited particularly, even in melt molding at high temperatures of, for example, no less than 260&#xb0; C. Further provided is a multilayered structure molded from the composition. The present invention provides a resin composition containing (A) an ethylene-vinyl alcohol copolymer, (B) a carboxylic acid and/or a carboxylate ion, and (C) a metal ion, wherein the component (B) includes (B2) a multivalent carboxylic acid and/or a multivalent carboxylate ion, and the molar ratio (B2/C) of the multivalent carboxylic acid and the multivalent carboxylate ion (B2) to the metal ion (C) is 0.002 or greater and 2 or less.

Resin composition, method for production thereof and multilayered structure

The present invention provides a method for producing a polymer by conducting polymerization in a polymerization reactor having an inner wall covered with an anti-fouling agent comprising an aqueous solution containing a polyvinyl alcohol obtained through saponification of a polyvinyl ester that contains monomer units having a silyl group. In the present invention, the polyvinyl alcohol satisfies the following formulae (I) and (II):370&#x3c;&#x3c;9000 &#x2003;&#x2003;(I)where P indicates the viscosity-average degree of polymerization of the polyvinyl alcohol, and S indicates the content (mole %) of the monomer units having a silyl group of formula (1) in the polyvinyl alcohol;0.2/100&#x2266;()/()&#x2266;75/100 &#x2003;&#x2003;(II)where A indicates the content (ppm) of silicon atoms in the polyvinyl alcohol, and B indicates the content (ppm) of silicon atoms in the polyvinyl alcohol that was washed with sodium hydroxide-containing methanol and then washed with methanol by Soxhlet extraction.

Anti-fouling agent and method for producing the same

The present invention provides a new dispersion stabilizer that satisfies, at a high level, the performances required for a dispersion stabilizer used for suspension polymerization. A method of producing a dispersion stabilizer that is useable for suspension polymerization of a vinyl compound and contains a vinyl alcohol polymer (A) includes producing the vinyl alcohol polymer (A) by heat-treating a vinyl alcohol polymer (B) at a temperature of 90 to 180&#xb0; C. for 0.5 to 20 hours in an atmosphere in which an oxygen concentration is 8000 ppm or lower. The vinyl alcohol polymer (B) has a saponification degree of at least 60 mol % and contains a residual acetic acid group whose block character is in the range of 0.3 to 0.6.

Dispersion stabilizer for suspension polymerization of vinyl compound and method of producing the same

A water-soluble resin composition is provided which comprises (i) 100 parts by weight of a polyvinyl alcohol polymer having a 1,2-glycol linkage content of at least 1.8 mole percent and a degree of hydrolysis of at least 90 mole percent, (ii) 1 to 50 parts by weight of a plasticizer and (iii) 5 to 50 parts by weight of a monosaccharide and/or a polysaccharide, optionally together with (iv) 1 to 20 parts by weight of an inorganic filler. Also provided is a water-soluble resin composition which comprise (i&prime;) 100 parts by weight of a polyvinyl alcohol polymer having a 1,2-glycol linkage content of at least 1.8 mole percent and a degree of hydrolysis of 92 to 99 mole percent, (ii&prime;) 1 to 50 parts by weight of a plasticizer and (iv&prime;) 1 to 20 parts by weight of an inorganic filler, optionally together with (iii&prime;) 5 to 50 parts by weight of a monosaccharide and/or polysaccharide. Further provided are water-soluble films produced by using those water-soluble resin compositions.

Water-soluble resin composition and water-soluble film

Vinyl alcohol polymers having an ethylene unit content of 2 to 19 mole %, a polymerization degree of 200 to 2,000, a degree of saponification of 80 to 99.99 mole % and a total content of carboxyl group and lactone rings of 0.02 to 0.4 mole % are excellent in thermal stability, water resistance, gas-barrier properties, water vapor-barrier property, stability of aqueous solution kept at low temperatures and biodegradability.

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Kurashiki, Japan

Kazuyuki Somemiya