Method for producing oxymethylene copolymer

Patent metadata

Field	Value
Publication number	US-9902797-B2
Application number	US-201314400075-A
Country	US
Kind code	B2
Filing date	May 10, 2013
Priority date	May 14, 2012
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

The present invention is directed to a method for producing an oxymethylene copolymer by subjecting trioxane and 1,3-dioxolane to copolymerization using boron trifluoride or a coordination compound thereof as a catalyst, wherein the copolymerization is conducted in the presence of a steric-hindrance phenol in an amount of 0.006 to 2.0% by weight, based on the weight of the trioxane, using 0.01 to 0.07 mmol of boron trifluoride or a coordination compound thereof as a catalyst, relative to 1 mol of the trioxane, and wherein, at a point in time when the polymerization yield becomes 92% or more, the formed oxymethylene copolymer and a polymerization terminator are contacted to terminate the polymerization.

First claim

The invention claimed is:

1. A method for producing an oxymethylene copolymer by subjecting trioxane and 1,3-dioxolane to copolymerization using boron trifluoride or a coordination compound thereof as a catalyst, comprising:
charging a monomer mixture of the trioxane and 1,3-dioxolane with a steric-hindrance phenol in an amount of 0.006 to 2.0% by weight, based on the weight of the trioxane, then
conducting the copolymerization using 0.01 to 0.07 mmol of boron trifluoride or a coordination compound thereof as a catalyst, relative to 1 mol of the trioxane to form the oxymethylene copolymer, and then
contacting the formed oxymethylene copolymer and a polymerization terminator to terminate the polymerization when the polymerization yield has reached at least 92%;
wherein the trioxane monomer contains 0.00001 to 0.003 mmol of triethanolamine, relative to 1 mol of the trioxane.

2. The method for producing an oxymethylene copolymer according to claim 1 , wherein a portion of or all of the steric-hindrance phenol is added through an inlet of a polymerizer.

3. The method for producing an oxymethylene copolymer according to claim 1 , wherein the polymerization terminator is at least one compound selected from the group consisting of triphenylphosphine, a hindered amine, and an alkylated melamine.

4. The method for producing an oxymethylene copolymer according to claim 1 , wherein the formed oxymethylene copolymer is contacted with the polymerization terminator when the polymerization yield has reached at least 97%.

5. The method for producing an oxymethylene copolymer according to claim 1 , wherein the oxymethylene copolymer is continuously produced using a continuous polymerization apparatus comprising a continuous polymerizer and a terminator mixing machine which are connected in series.

6. A method for producing an oxymethylene copolymer, comprising: subjecting the oxymethylene copolymer obtained by the method for producing an oxymethylene copolymer according to claim 1 to stabilization treatment by further melt-kneading the oxymethylene copolymer at a temperature in the range of from the melting temperature of the oxymethylene copolymer to a temperature 100° C. higher than the melting temperature under a pressure of 760 to 0.1 mmHg.

7. The method for producing an oxymethylene copolymer according to claim 6 , wherein the stabilization treatment is performed by means of an apparatus comprising a combination of a single-screw or twin- or multi-screw vented extruder and a surface renewal-type mixer.

8. The method for producing an oxymethylene copolymer according to claim 6 , wherein the oxymethylene copolymer is subjected to the stabilization treatment without being washed after termination of the polymerization.

Assignees

• Mitsubishi Gas Chemical Co

Inventors

• Nakaya Daigo
• Miyoshi Tsutomu
• Ito Akira
• Mochida Satoshi

Classifications

• C08G2/28

  Post-polymerisation treatments · CPC title

• C08G2/10 Primary

  Polymerisation of cyclic oligomers of formaldehyde · CPC title

• C08G4/00 Primary

  Condensation polymers of aldehydes or ketones with polyalcohols; Addition polymers of heterocyclic oxygen compounds containing in the ring at least once the grouping —O—C—O— (of cyclic oligomers of aldehydes C08G2/00) · CPC title

• C08G2/06

  Catalysts (Catalysts in general B01J) · CPC title

• C08G2/30

  Chemical modification by after-treatment · CPC title