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 C. or lower until the conversion reaches 50% and thereafter at a polymerization environment temperature of 115 C. to 140 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.

The present invention relates to a process for producing cyclic acetal comprising i) preparing a reaction mixture comprising a) a formaldehyde source in a liquid medium and b) a catalyst; ii) converting the formaldehyde source into cyclic acetals, wherein the final conversion of said formaldehyde source to said cyclic acetal is greater than 10% on basis of the initial formaldehyde source.

The present invention relates to a process for producing cyclic acetal comprising i) preparing a reaction mixture comprising a) a formaldehyde source in a liquid medium and b) a catalyst; ii) converting the formaldehyde source into cyclic acetals, wherein the final conversion of said formaldehyde source to said cyclic acetal is greater than 10% on basis of the initial formaldehyde source.

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 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 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 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.

The present invention relates to a process for producing cyclic acetal comprising i) preparing a liquid reaction mixture comprising a) a formaldehyde source, b) an aprotic compound and c) a catalyst; wherein the total amount of protic compounds is less than 40 wt.-%, based on the total weight of the reaction mixture; and ii) converting the formaldehyde source into cyclic acetals.

The present invention relates to a process for producing cyclic acetal comprising i) preparing a liquid reaction mixture comprising a) a formaldehyde source, b) an aprotic compound and c) a catalyst; wherein the total amount of protic compounds is less than 40 wt.-%, based on the total weight of the reaction mixture; and ii) converting the formaldehyde source into cyclic acetals.

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 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 C. and less than 140 C.; supplying the separated monomers to the raw material supply; and recovering the polyacetal copolymer from the reaction mixture.

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 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 C. and less than 140 C.; supplying the separated monomers to the raw material supply; and recovering the polyacetal copolymer from the reaction mixture.

A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.