Polyplastics Co., Ltd.

Eiji Masuda

Kaoru Yamamoto

Tomohiro Monma

Hiroyuki Kanai

Tadahiro Horiguchi

Akira Nakai

Shoji Sanada

Hajime Serizawa

Katsuhei Ohnishi

Hiroaki Nakao

A high-quality polyacetal produced by a process including supplying a raw material comprising trioxane, a comonomer capable of copolymerizing with trioxane and a non-volatile protonic acid to a reactor of a continuous stirring/mixing machine type; carrying out a polymerization reaction of the raw material to produce a reaction mixture; vaporizing an unreacted monomer to separate the unreacted monomer from the reaction mixture and supplying the unreacted monomer to the raw material supplying; collecting a polyacetal copolymer from the reaction mixture into a collection unit which is arranged downstream from a discharge port and is adjusted to have a gauge pressure of 0.2 kPa or more; and adding a basic compound to the collected polyacetal and then subjecting the resultant mixture to a melt-kneading treatment to deactivate the non-volatile protonic acid.

Method for producing polyacetal copolymer

A process for producing a polyacetal copolymer, the process making catalyst deactivation easy and efficient. Trioxane as a major monomer is copolymerized with one or more comonomers that are a cyclic ether and/or cyclic formal having at least one carbon-carbon bond, using a nonvolatile protonic acid as a polymerization catalyst at 100&#xb0; C. or lower until the conversion reaches 50% and thereafter at a polymerization environment temperature of 115&#xb0; C. to 140&#xb0; C. This process includes: a crushing step in which a dry-process crusher is used to obtain a crude polyacetal copolymer crushed to such a degree that when the crude copolymer is screened with a sieve having an opening size of 11.2 mm, 90 parts by weight or more thereof passes therethrough; and a deactivation step in which a basic compound (e) is added to the crude copolymer and the mixture is melt-kneaded to thereby deactivate the polymerization catalyst.

Process for producing polyacetal copolymer

A production method for a polyacetal copolymer that makes deactivation of a catalyst simple and efficient and that achieves a high polymerization yield and high quality using equipment that does not require a cleaning step and a process that involves a simple operation technique. The production method for a polyacetal copolymer uses trioxane as a main monomer and a cyclic ether and/or a cyclic formal having at least one carbon-carbon bond as a comonomer. In the production method, a predetermined heteropoly acid is used as a polymerization catalyst to perform copolymerization, a predetermined salt is added to the reaction product, melt kneading processing is performed, and the polymerization catalyst is deactivated.

Production method for polyacetal copolymer

A high-quality polyacetal copolymer produced by a simple process and in an economical manner. The method includes supplying a raw material including trioxane or the like to a reaction device; obtaining a reaction mixture by carrying out a polymerization reaction of the raw material in the state where the rotating shafts are inclined by 1 to 6&#xb0; upwards with respect to the horizontal direction H from the introduction opening towards a polyacetal copolymer recovery portion; vaporizing and separating an unreacted monomer from the reaction mixture using a vaporization and separation portion; re-supplying the unreacted monomer to the reaction device; and recovering the polyacetal copolymer from the reaction using a polyacetal copolymer recovery portion.

A high-quality polyacetal copolymer produced by a simple process in an economical manner. The process includes supplying a raw material including trioxane and the like to a reaction device; setting the polymerization environmental temperature to no more than 100&#xb0; C. until the reaction device conversion rate becomes 0.5, and then carrying out further polymerization; vaporizing and separating unreacted monomers from the reaction mixture at an environmental temperature of at least 115&#xb0; C. and less than 140&#xb0; C.; supplying the separated monomers to the raw material supply; and recovering the polyacetal copolymer from the reaction mixture.

Modified polyacetal and method of producing the same

A process for producing a polyacetal copolymer, which is extremely heat-stable and is extremely reduced in the quantity of unstable terminals even in a high polymerization yield in which trioxane as the principal monomer, comprises copolymerization of trioxane as the principal monomer with a cyclic ether or cyclic formal having at least one carbon-to-carbon bond as the comonomer by using a specific heteropoly-acid or acid salt thereof as a polymerization catalyst until the content of the remaining monomers is lowered to at most 10% by weight based on all the monomers fed, adding 0.01 to 10% by weight, based on the resulting crude polymer, of a solution containing a catalyst deactivator, or contacting a basic gas as the deactivator to deactivate the catalyst, and subjecting the crude polymer as such to heat melting treatment without washing thereof.

Process for preparing polyacetal copolymer

The present invention provides a process for preparing a thermally very stable polyacetal copolymer having very small unstable terminals even at a high polymerization yield, by the copolymerization of trioxane as the principal monomer with a comonomer copolymerizable therewith, wherein an isopolyacid or an acidic salt thereof is used as a polymerization catalyst; the catalyst can simply be deactivated in a small amount of a deactivator solution after the polymerization; and a washing step is not required. The copolymerization is effected with an isopolyacid or an acidic salt thereof used as a polymerization catalyst until the remaining monomers account for at most 10% by weight of all the fed monomers, and a solution containing a deactivator for the above catalyst is added in an amount of 0.01 to 10% by weight based on the resulting crude polymer to deactivate the catalyst, followed by subjecting the crude polymer intact to a heat-melting treatment without washing it.

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Fuji, Japan

Eiji Masuda