Oxymethylene copolymer resin composition and method for producing same

An oxymethylene copolymer resin composition, which comprises:

• (i) an oxymethylene copolymer comprising an oxymethylene unit and an oxyalkylene unit containing 2 or more carbon atoms,
• (ii) a fluorine adduct of a boron compound having 1 to 3 aryl groups containing fluorine atom, and
• (iii) a layered double hydroxide,
• wherein (ii) the fluorine adduct of the boron compound is derived from (ii′) the boron compound and (ii″) a boron trifluoride compound represented by BF3.(α)m, wherein m represents 0 or 1, and α represents alkyl ether containing 2 to 20 carbon atoms, tetrahydrofuran, or phenol,
• wherein the layered double hydroxide is a hydrotalcite,
• wherein the boron compound is at least one selected from the group consisting of tris(pentafluorophenyl)borane, bis(pentafluorophenyl)fluoroborane, pentafluorophenyldifluoroborane, tris(2,3,4,5-tetrafluorophenyl)boron, tris(2,3,4,6-tetrafluorophenyl)boron, tris(2,3,5,6-tetrafluorophenyl)boron, tris(2,3,5-trifluorophenyl)boron, tris(2,4,6-trifluorophenyl)boron, tris(1,3-difluorophenyl)boron, tris(2,3,5,6-tetrafluoro-4-methylphenyl)boron, tris(2,3,4,6-tetrafluoro-5-methylphenyl)boron, tris(2,4,5-trifluoro-6-methylphenyl)boron, tris(2,3,6-trifluoro-4-methylphenyl)boron, tris(2,4,6-trifluoro-3-methylphenyl)boron, tris(2,6-difluoro-3-methylphenyl)boron, tris(2,4-difluoro-5-methylphenyl)boron, tris(3,5-difluoro-2-methylphenyl)boron, tris(4-methoxy-2,3,5,6-tetrafluorophenyl)boron, tris(3-methoxy-2,4,5,6-tetrafluorophenyl)boron, tris(2-methoxy-3,5,6-trifluorophenyl)boron, tris(3-methoxy-2,5,6-trifluorophenyl)boron, tris(3-methoxy-2,4,6-trifluorophenyl)boron, tris(2-methoxy-3,5-difluorophenyl)boron, tris(3-methoxy-2,6-difluorophenyl)boron, tris(3-methoxy-4,6-difluorophenyl)boron, tris(2-methoxy-4,6-difluorophenyl)boron, tris(4-methoxy-2,6-difluorophenyl)boron, and hydrates thereof,
• wherein a content of (iii) the layered double hydroxide is 0.003 to 1 parts by mass, based on 100 parts by mass of (i) the oxymethylene copolymer.

A method for producing an oxymethylene copolymer resin composition, comprising:

• a step of performing a copolymerization reaction, using (i′) trioxane as a main monomer, (i″) cyclic ether and/or cyclic formal having at least one carbon-carbon bond, as a comonomer, and (ii′) a boron compound having 1 to 3 aryl groups containing fluorine atom and (ii″) a boron trifluoride compound represented by BF3.(α)m, wherein m represents 0 or 1 and a represents alkyl ether containing 2 to 20 carbon atoms, tetrahydrofuran, or phenol, as reaction initiators, to obtain a reaction product comprising (i) an oxymethylene copolymer, and
• a step of adding (iii) a layered double hydroxide to the obtained reaction product,
• wherein the production method is characterized in that the additive amount of (iii) the layered double hydroxide is 0.003 to 1 parts by mass, based on 100 parts by mass of (i) the oxymethylene copolymer,
• wherein the layered double hydroxide is a hydrotalcite,
• wherein the boron compound is at least one selected from the group consisting of tris(pentafluorophenyl)borane, bis(pentafluorophenyl)fluoroborane, pentafluorophenyldifluoroborane, tris(2,3,4,5-tetrafluorophenyl)boron, tris(2,3,4,6-tetrafluorophenyl)boron, tris(2,3,5,6-tetrafluorophenyl)boron, tris(2,3,5-trifluorophenyl)boron, tris(2,4,6-trifluorophenyl)boron, tris(1,3-difluorophenyl)boron, tris(2,3,5,6-tetrafluoro-4-methylphenyl)boron, tris(2,3,4,6-tetrafluoro-5-methylphenyl)boron, tris(2,4,5-trifluoro-6-methylphenyl)boron, tris(2,3,6-trifluoro-4-methylphenyl)boron, tris(2,4,6-trifluoro-3-methylphenyl)boron, tris(2,6-difluoro-3-methylphenyl)boron, tris(2,4-difluoro-5-methylphenyl)boron, tris(3,5-difluoro-2-methylphenyl)boron, tris(4-methoxy-2,3,5,6-tetrafluorophenyl)boron, tris(3-methoxy-2,4,5,6-tetrafluorophenyl)boron, tris(2-methoxy-3,5,6-trifluorophenyl)boron, tris(3-methoxy-2,5,6-trifluorophenyl)boron, tris(3-methoxy-2,4,6-trifluorophenyl)boron, tris(2-methoxy-3,5-difluorophenyl)boron, tris(3-methoxy-2,6-difluorophenyl)boron, tris(3-methoxy-4,6-difluorophenyl)boron, tris(2-methoxy-4,6-difluorophenyl)boron, tris(4-methoxy-2,6-difluorophenyl)boron, and hydrates thereof.