JP2017226792A - Method for producing polyacetal copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyacetal copolymer having a stabilized terminal that shows excellent heat stability, less coloring and less foreign matter.SOLUTION: A method for producing a polyacetal copolymer includes the terminal stabilization of (A) a polyacetal copolymer before terminal stabilization in the presence of (B) a stabilizer and (C) an inorganic filler. The method makes it possible to provide polyacetal copolymer having a stabilized terminal that shows excellent heat stability, less coloring and less foreign matter.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a polyacetal copolymer.

  Since polyacetal copolymers have balanced mechanical properties and excellent fatigue properties, they are widely used in parts such as automobiles, electronic devices, and electric devices.

The polyacetal copolymer is produced by copolymerizing formaldehyde or a cyclic acetal such as trioxane, which is a cyclic trimer thereof, and either or both of a cyclic ether and a cyclic formal. However, the polyacetal copolymer obtained by such copolymerization has — (OCH ₂ ) _n —OH groups at some molecular ends, and this — (OCH ₂ ) _n —OH groups are thermally unstable. Therefore, it is easily decomposed by heating at the time of molding and generates a large amount of formaldehyde, so it cannot be put into practical use as it is. That is, when a large amount of formaldehyde is generated, the resin foams at the time of molding, or a line from which gaseous formaldehyde is removed remains on the surface of the molded product, resulting in problems such as poor appearance. Furthermore, the generated formaldehyde is oxidized by oxygen in the molding machine to form formic acid, and the formic acid accelerates the main chain decomposition of the polyacetal copolymer.

As a method for stabilizing such a polyacetal copolymer having a — (OCH ₂ ) _n —OH group which is a thermally unstable end group, for example, two extruders are used and one extruder is used. It is known that the end of the polyacetal copolymer is stabilized at the end, the stabilizer and / or additive is melt-kneaded in the other extruder, and then supplied to the extruder where the end-stabilized polyacetal copolymer is present. (See Patent Document 1). Further, a method is known in which an antioxidant is added to a polyacetal copolymer before terminal stabilization and stabilization is performed using a specific quaternary ammonium compound (see Patent Documents 2 and 3).

International Publication No. 1996/23825 Pamphlet International Publication No. 1998/42781 Pamphlet JP 2006-282836 A

When kneading a polyacetal copolymer and an additive, since the polyacetal copolymer before the terminal stabilization has a thermally unstable structure, generally, the polyacetal copolymer is first stabilized, Thereafter, the polyacetal copolymer whose terminal is stabilized and the additive are kneaded. However, a polyacetal copolymer obtained by kneading an additive after terminal stabilization may not be sufficiently satisfactory in terms of thermal stability, reduction of coloring, and reduction of foreign matters.
Accordingly, an object of the present invention is to provide a terminal-stabilized polycetal copolymer that has excellent thermal stability, little coloration, and little foreign matter.

  As a result of diligent research, the inventors of the present invention have achieved excellent thermal stability and less coloring by a method in which terminal stabilization of the polyacetal copolymer before terminal stabilization is performed in the presence of a stabilizer and an inorganic filler. The inventors have found that a terminal-stabilized polycetal copolymer with little foreign matter can be obtained, and the present invention has been completed.

That is, the present invention is as follows.
[1]
(A) The manufacturing method of a polyacetal copolymer including performing terminal stabilization of the polyacetal copolymer before terminal stabilization in presence of (B) stabilizer and (C) inorganic filler.
[2]
(A) Polyacetal copolymer before terminal stabilization, (B) stabilizer, (C) inorganic filler, and (D) terminal stabilizer are degassed under reduced pressure while being melt-kneaded [1] A process for producing the polyacetal copolymer described in 1.
[3]
(A) Polyacetal copolymer before terminal stabilization, (B) stabilizer, and (C) inorganic filler are melt-kneaded, and then (D) terminal stabilizer is added and melt-kneaded, followed by depressurization under reduced pressure. The method for producing a polyacetal copolymer according to [1], which is characterized by concern.
[4]
(B) The method for producing a polyacetal copolymer according to any one of [1] to [3], wherein the stabilizer is an antioxidant and / or a form catcher agent.
[5]
(C) The production of the polyacetal copolymer according to any one of [1] to [4], wherein the inorganic filler is one or more selected from calcium carbonate, talc and wollastonite. Method.
[6]
(C) The method for producing a polyacetal copolymer according to any one of [1] to [5], wherein the inorganic filler has an average particle size of 1 μm or more.

  According to the method for producing a polyacetal copolymer of the present invention, it is possible to produce a stabilized polyacetal copolymer having excellent thermal stability, little coloring, and few foreign substances.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following description, In the range of the summary, various deformation | transformation can be implemented.

The manufacturing method of the polyacetal copolymer of this embodiment includes (A) performing terminal stabilization of the polyacetal copolymer before terminal stabilization in the presence of (B) a stabilizer and (C) an inorganic filler. And a method for producing a polyacetal copolymer.
By the method for producing a polyacetal copolymer of the present embodiment, a stabilized polyacetal copolymer having excellent thermal stability, little coloring, and few foreign substances can be obtained.

  Moreover, the polyacetal copolymer in this embodiment refers to the polyacetal copolymer obtained by the manufacturing method of this embodiment.

In the present embodiment, as a method for performing terminal stabilization in the presence of (B) a stabilizer and (C) an inorganic filler, for example,
Method 1: (A) A method of degassing under reduced pressure while melt kneading the polyacetal copolymer before terminal stabilization, (B) stabilizer, (C) inorganic filler, and (D) terminal stabilizer, and Method 2 : (A) Polyacetal copolymer before terminal stabilization, (B) stabilizer, and (C) inorganic filler are melt-kneaded, then (D) terminal stabilizer is added, melt-kneaded, and further decompressed How to deaerate,
Etc.

In any of the above methods, (A) As a method of adding each component to the polyacetal copolymer before terminal stabilization, [1 ′] (A) terminal stabilization before supplying each component to the extruder A method of adding and mixing to the previous polyacetal copolymer; [2 ′] A method in which each component is fed to the extruder at the location (A) where the polyacetal copolymer before terminal stabilization is present. .
In addition, in the method of [1 ′] and [2 ′] above, (A) the polyacetal copolymer before terminal stabilization to which the stabilizer (B) and the inorganic filler (C) are added is (A) terminal. It may be a mixture of a polyacetal copolymer before stabilization and (D) a terminal stabilizer.

In Method 1, when (D) terminal stabilizer is added, [1] (D) a method in which terminal stabilizer is added in advance to (A) the polyacetal copolymer before terminal stabilization; 2] (D) A method of adding a terminal stabilizer to the polyacetal copolymer melted in an extruder is preferably mentioned.
Here, in the case of the method of adding in advance in the above [1], the (D) terminal stabilizer can be added as it is or diluted with water or the like. It is preferable to dry at a temperature of 100 ° C. or higher so that the moisture content is 100 ppm or less, preferably 50 ppm or less.

  In addition, in the methods [1] and [2] above, (D) the polyacetal copolymer before terminal stabilization to which the terminal stabilizer is added is the (A) polyacetal copolymer before terminal stabilization. A mixture of a polymer and (B) stabilizer, (A) a polyacetal copolymer before terminal stabilization and (C) a mixture of inorganic fillers, and (A) a polyacetal copolymer before terminal stabilization, (B) It may be a mixture of a stabilizer and (C) an inorganic filler, but is a polyacetal copolymer before (A) terminal stabilization before mixing of (B) stabilizer and / or (C) inorganic filler. Is preferred.

  Moreover, in the said method 1 and method 2, what was used as the masterbatch obtained by melt-kneading a polyacetal copolymer (B) stabilizer and (C) inorganic filler beforehand can also be used.

  These melt-kneading can be performed using a conventionally known apparatus and operation as appropriate. Examples of the apparatus include a single-screw extruder with a vent and a twin-screw extruder with a vent provided with a melting zone, a terminal stabilization zone, and a vacuum degassing zone. The terminal stabilization is preferably performed at a temperature not lower than the melting point of the polyacetal copolymer and not higher than 260 ° C. from the viewpoint of coloring and molecular weight control.

  The melt-kneading can be performed by appropriately using conventionally known apparatuses and operations. Examples of the apparatus include a single-screw extruder with a vent and a twin-screw extruder with a vent provided with a melting zone, a terminal stabilization zone, and a vacuum degassing zone. The terminal stabilization is preferably performed at a temperature not lower than the melting point of the polyacetal copolymer and not higher than 260 ° C. from the viewpoint of coloring and molecular weight control.

(A: polyacetal copolymer before terminal stabilization)
The polyacetal copolymer before terminal stabilization in the present embodiment is not particularly limited as long as it is a polyacetal copolymer obtained by polymerization by a known method and a polyacetal copolymer having an unstable terminal portion. For example, a polyacetal copolymer having a — (OCH ₂ ) _n —OH group at a part of molecular terminals of the polyacetal copolymer and easily decomposing by heating or the like to generate formaldehyde can be preferably exemplified. .

  The polyacetal copolymer before terminal stabilization is, for example, formaldehyde or a cyclic acetal such as trioxane, which is a cyclic trimer thereof, and a known comonomer that can be copolymerized therewith, for example, a cyclic ether or a cyclic formal. And a copolymer having two or more linked carbon atoms in the main chain, obtained by copolymerization using a known polymerization catalyst. In addition, a multi-element copolymer obtained by copolymerizing a monomer or a multi-component monomer containing a diglycidyl compound, or a copolymer having a branched or crosslinked structure in the molecule is also used as the polyacetal copolymer used in the production method of the present invention. included.

  Although it does not restrict | limit especially as a polymerization method, For example, block polymerization can be mentioned suitably, This block polymerization may be any of a batch type and a continuous type. The bulk polymerization is generally performed by using a monomer in a molten state and obtaining a solid bulk polymer as the polymerization reaction proceeds.

Among the polyacetal copolymers before terminal stabilization, polyacetal copolymers obtained using trioxane are preferable. Trioxane is generally obtained by reacting a formalin aqueous solution in the presence of an acidic catalyst, but may contain impurities that cause chain transfer such as water, methanol, formic acid, methyl formate, etc. It is preferable to remove and purify the impurities in advance by this method. In that case, the total amount of impurities to be chain transfer, to the trioxane 1 mol, preferably to 1 × 10 ^-3 mol or less, and more preferably set to 0.5 × 10 ^-3 mol or less.

  Examples of the comonomer include ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxatan, 1,3-dioxolane, ethylene glycol formal, propylene glycol formal, diethylene glycol formal, and triethylene. Examples include glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, etc. These may be used alone or in combination of two or more. You may use together. Among the comonomers, 1,3-dioxolane and 1,4-butanediol formal are preferable. The amount of comonomer added is preferably 0.3 mol% or more, more preferably 0.5 mol% or more, relative to 1 mol of trioxane.

Examples of the polymerization catalyst include Lewis acids such as boric acid, tin, titanium, phosphorus, arsenic and antimony halides, boron trifluoride, boron trifluoride hydrate, and oxygen atom or sulfur atom. A coordination complex compound of an organic compound containing and boron trifluoride is preferable. More specifically, preferred examples include boron trifluoride, boron trifluoride diethyl etherate, and boron trifluoride di-n-butyl etherate. These may be used alone or in combination of two or more. The addition amount of the polymerization catalyst is preferably in the range of ^{0.1 × 10 -5 ~0.1 × 10 -3} mol relative to trioxane 1 mol, more preferably 0.3 × 10 ^-5 ~0.8 × 10 ^- It is the range of ⁴ mol, More preferably, it is the range of 0.5 * 10 < ^-5 > -0.6 * 10 < ^-4 > mol.

  The polymerization reaction can be stopped by deactivating the assembly catalyst. The deactivation of the polymerization catalyst is carried out by converting the polyacetal copolymer obtained by the polymerization reaction into amines such as ammonia, triethylamine, tri-n-butylamine, or alkali metal or alkaline earth metal hydroxides, inorganic acid salts, It is carried out by charging into an aqueous solution or an organic solvent solution containing at least one kind of catalyst neutralization deactivator such as an organic acid salt and stirring in a slurry state for several minutes to several hours. The slurry after the catalyst neutralization deactivation is filtered and washed to remove unreacted monomers, the catalyst neutralization deactivator and the catalyst neutralization salt, and then dried to obtain a polyacetal copolymer before terminal stabilization. be able to. Further, the deactivation of the polymerization catalyst includes at least one of a method of deactivating the polymerization catalyst by contacting a vapor such as ammonia and triethylamine with a polyacetal copolymer, a hindered amine, triphenylphosphine, and calcium hydroxide. It is also possible to use a method in which the catalyst is deactivated by contacting the polyacetal copolymer with a polyacetal copolymer.

The polyacetal copolymer in which the polymerization catalyst is reduced in volatilization is heated by heating in an inert gas atmosphere at a temperature below the melting point of the polyacetal copolymer without deactivating the polymerization catalyst. It can also use for the manufacturing method of a polymer.
The above-described deactivation operation of the polymerization catalyst and the volatilization reduction operation of the polymerization catalyst may be performed after pulverizing the polyacetal copolymer obtained by the polymerization reaction, if necessary.

(B: Stabilizer)
As a stabilizer in the present embodiment, as long as the effect of the present embodiment is not impaired, an antioxidant, a form catcher agent, an ultraviolet absorber, a lubricant, and additives that are used in conventional polyacetal resins, and An antistatic agent or the like can be used. These may be used alone or in combination of two or more. Among these, antioxidants and form catcher agents can be preferably used.

  Examples of the antioxidant include n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate, n-octadecyl-3- (3′-methyl-5′-). t-butyl-4′-hydroxyphenyl) propionate, n-tetradecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate, 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,4-butanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propion, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) Nyl) propionate], tetrakis [methylene-3- (3′-t-butyl-4-hydroxyphenyl) propionate] methane, N, N′-bis [3- (3,5-di-t-butyl-4- Hydroxyphenyl) propionyl] hydrazine, N, N′-tetramethylene-bis [3- (3′-methyl-5′-t-butyl-4-hydroxyphenol) propionyl] diamine, N, N′-bis [3- (3 ′, 5′-di-t-butyl-4-hydroxyphenol) propionyl] hexamethylenediamine, 3- (N-salicyloyl) amino-1,2,4-triazole, N, N′-bis {2- [3- (3,5-dibutyl-4-hydroxyphenyl) propionyloxy] ethyloxy} amide, N, N′-hexamethylene-bis [3- (3,5- - and butyl-4-hydroxyphenyl) propane) amide, the antioxidant may be used alone or may be used in combination of two or more. Among the above antioxidants, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], tetrakis [methylene-3- (3′-t-butyl) are preferable. -4-hydroxyphenyl) propionate] methane, N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine.

  The form catcher agent is not particularly limited as long as it can capture formaldehyde or formic acid, and examples thereof include polyamide resins, amide compounds, urea derivatives, triazine derivatives, and the like. Or two or more of them may be used in combination. Among the above form catcher agents, triazine derivatives are preferable.

  Examples of the polyamide resin include nylon 6, nylon 11, nylon 12, nylon 66, nylon 6/10, nylon 6/6, nylon obtained by condensation of diamine and dicarboxylic acid, amino acid condensation, lactam ring-opening polymerization, and the like. 10, nylon 6 / 6.6, nylon 6.6 / 6.10, nylon 6 / 6.6 / 6.10, poly-.beta.-alanine and the like.

  The amide compound is produced from an aliphatic monocarboxylic acid, an aliphatic dicarboxylic acid, an aromatic monocarboxylic acid or an aromatic dicarboxylic acid and an aliphatic monoamine, an aliphatic diamine, an aromatic monoamine or an aromatic diamine. There is no particular limitation as long as it is, for example, stearyl stearic acid amide, stearyl oleic acid amide, stearyl erucic acid amide, ethylenediamine-distearic acid amide, ethylenediamine-dibehenic acid amide, hexamethylenediamine-distearic acid amide, ethylenediamine-dierucic acid amide, Examples include xylylenediamine-dierucamide, di (xylylenediamine-stearic acid amide), and sebacic acid amide.

  Examples of the urea derivative include N-phenylurea, N, N′-diphenylurea, N-phenylthiourea, N, N′-diphenylthiourea and the like.

  Examples of triazine derivatives include melamine, benzoguanamine, N-phenylmelamine, melem, N, N′-diphenylmelamine, N-methylolmelamine, N, N′-trimethylolmelamine, and 2,4-diamino-6-cyclohexyltriazine. And triazine derivatives such as melam. Among the above triazine derivatives, melamine is preferable.

  The added amount of the stabilizer is 100 parts by mass of the polyacetal copolymer before terminal stabilization, and if the added amount is less than 0.001 parts by mass, the thermal stability deteriorates due to insufficient stabilization, and 5.0 parts by mass is added. Since coloring will become intense when it exceeds, it is 0.001-5.0 mass part, It is preferable that it is 0.002-4.0 mass part, It is more preferable that it is 0.003-3.0 mass part. .

(C: inorganic filler)
The inorganic filler used in the present invention is not particularly limited as long as it does not hinder terminal stabilization of the polyacetal copolymer before terminal stabilization and does not adversely affect the polyacetal resin before and after terminal stabilization. For example, oxides such as silica; hydroxides such as calcium hydroxide; carbonates such as calcium carbonate; sulfates such as barium sulfate; silicates such as talc, mica and wollastonite These may be used alone or in combination of two or more. Among the inorganic fillers, calcium carbonate, talc, and wollastonite are preferable. The average particle diameter is preferably 1 μm or more, more preferably 5 μm or more, from the viewpoint of thermal stability and foreign matter.

  The amount of the inorganic filler added is less than 0.001 part by mass with respect to 100 parts by mass of the polyacetal copolymer before terminal stabilization, and the thermal stability deteriorates due to insufficient stabilization. Is 0.001 to 0.5 parts by mass, preferably 0.003 to 0.4 parts by mass, and more preferably 0.005 to 0.3 parts by mass.

(D: terminal stabilizer)
The terminal stabilizer in the present embodiment is not particularly limited as long as it decomposes and removes the unstable terminal portion of the polyacetal copolymer before terminal stabilization and stabilizes,
ammonia;
Aliphatic amine compounds such as triethylamine and tributylamine;
Alkali metal or alkaline earth metal hydroxides such as sodium, potassium, magnesium, calcium or barium;
Inorganic weak acid salts of alkali metals or alkaline earth metals, such as carbonates, phosphates, silicates and borates;
Alkali metal or alkaline earth metal organic acid salts such as formate, acetate, stearate, palmitate, propionate and oxalate;
Among these, an aliphatic amine compound is preferable, and triethylamine is more preferable.

  The addition amount of ammonia or the amine compound is 0.05 to 50 ppm by mass in terms of nitrogen with respect to 100 parts by mass of the polyacetal copolymer before terminal stabilization. The addition amount of the alkali metal or alkaline earth metal hydroxide, inorganic weak acid salt, or organic acid salt is 2 to 5,000 ppm with respect to 100 parts by mass of the polyacetal copolymer before terminal stabilization.

  Moreover, the quaternary ammonium compound represented by following General formula (1) can also be used conveniently.

[R ¹ R ² R ³ R ⁴ N ⁺ ] _n X ⁻ⁿ (1)

In the formula, each of R ¹ , R ² , R ³ , and R ⁴ independently represents an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 6 to 20 carbon atoms. Or an alkylaryl group in which an aryl group having 6 to 20 carbon atoms is substituted with at least one unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms.
The unsubstituted alkyl group and the substituted alkyl group are linear, branched, or cyclic.
The substituent of the substituted alkyl group is a halogen, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, or an amide group.
The aryl hydrogen atom in the aryl group, aralkyl group and alkylaryl group may be substituted with a halogen.
n represents an integer of 1 to 3. X represents a hydroxyl group or an acid residue of a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, an oxo acid, an inorganic thioacid, or an organic thioacid having 1 to 20 carbon atoms.

As a quaternary ammonium compound represented by the following general formula (1), for example, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1,6 -Hexamethylene bis (trimethylammonium), decamethylene bis (trimethylammonium), trimethyl-3-chloro-2-hydroxypropylammonium, trimethyl (2-hydroxyethyl) ammonium, triethyl (2-hydroxyethyl) ammonium, tripropyl ( 2-hydroxyethyl) ammonium, tri-n-butyl (2-hydroxyethyl) ammonium, trimethylbenzylammonium, tri-n-butylbenzylammo , Trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, octadecyltri (2-hydroxyethyl) ammonium, tetrakis (hydroxyethyl) ammonium, etc., and these can be used alone. Or two or more of them may be used in combination. Among the above quaternary ammonium compounds, triethyl (2-hydroxyethyl) ammonium and tripropyl (2-hydroxyethyl) ammonium are preferable.
The form of the quaternary ammonium compound is a hydroxide; a hydrogen salt such as hydrochloric acid, odorous acid or hydrofluoric acid; a sulfuric acid, a phosphoric acid nitrate, a carbonic acid, a boric acid, a chloric acid, an iodic acid, a silicic acid or a perchloric acid. Oxo acid salts such as chlorous acid, hypochlorous acid, chlorosulfuric acid, amidosulfuric acid, disulfuric acid, tripolyphosphoric acid; formic acid, acetic acid, propionic acid, butanoic acid, isobutyric acid, pentanoic acid, caproic acid, caprylic acid, benzoic acid Although it may be in the form of a carboxylate such as acid or oxalic acid, the hydroxide is a strong alkali and needs to be handled with care, so it is preferably used in the form of a salt. Preferably, formate is more preferable.

  The addition amount of the quaternary ammonium compound is 0.05 to 50 mass ppm in terms of the amount of nitrogen derived from the quaternary ammonium compound with respect to 100 parts by mass of the polyacetal copolymer before terminal stabilization.

  Hereinafter, the present invention will be described in detail with specific examples and comparative examples, but the present invention is not limited to the following examples. In addition, the measuring method of the term and characteristic in an Example and a comparative example is as follows.

(A: Polycetal copolymer before terminal stabilization)
A jacketed biaxial paddle type continuous polymerization reactor (Kurimoto Corporation, diameter 2B, L / D = 14.8) through which a heat medium can pass was adjusted to a temperature of 80 ° C. As a polymerization catalyst, boron trifluoride-di-n-butyl etherate was diluted with cyclohexane to 0.26% by mass, a catalyst preparation solution was 69 g / hour, trioxane was 3500 g / hour, and 1,3-dioxolane was 121 g / hour. Polymerization was carried out by continuously supplying methylal as a molecular weight regulator at 1.8 g / hr to the polymerization reactor. What was discharged | emitted from the polymerization reactor was thrown into 0.5 mass% triethylamine aqueous solution, and after deactivating a polymerization catalyst, filtration, washing | cleaning, and drying were performed, and the polyacetal copolymer was obtained. The obtained polyacetal copolymer had a polymerization yield of 80%, a melting point of 164 ° C., and a melt flow index of 9.8 g / 10 minutes.

(B: Stabilizer)
B-1: Triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] (Irganox 245, manufactured by BASF Corporation)
B-2: Tetrakis [methylene-3 (3′-t-butyl-4-hydroxyphenyl) propionate] methane (Irganox 1010, manufactured by BASF Corporation)
B-3: N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine (Irganox MD1024, manufactured by BASF Corporation)
B-4: Melamine (manufactured by Nissan Chemical Industries, Ltd.)

(C: inorganic filler)
C-1: Talc (MS (surface untreated, average particle size 14.2 μm), manufactured by Nippon Talc Co., Ltd.)
C-2: Talc (P-3 (surface untreated, average particle size 5.1 μm), manufactured by Nippon Talc Co., Ltd.)
C-3: Talc (D-600 (surface untreated, average particle size 0.6 μm), manufactured by Nippon Talc Co., Ltd.)
C-4: Wollastonite (VM-8N (surface untreated, average particle diameter 11 μm), manufactured by Hayashi Kasei Co., Ltd.)
C-5: Calcium carbonate (BF-200 (surface untreated, average particle size 5 μm), manufactured by Shiraishi Calcium Co., Ltd.)
C-6: Calcium carbonate (Softon 2200 (surface untreated, average particle size 1 μm), manufactured by Shiraishi Calcium Co., Ltd.)

(D: terminal stabilizer)
D-1: Triethylamine D-2: Triethyl (2-hydroxyethyl) ammonium formate D-3: Tripropyl (2-hydroxyethyl) ammonium formate

(Measurement of thermal stability)
The stabilized polyacetal copolymer was dissolved in the downstream of nitrogen at 230 ° C., formaldehyde generated in 50 minutes was absorbed in water, and the amount (ppm) of formaldehyde was measured by titration. The smaller the amount (ppm) of formaldehyde, the higher the thermal stability of the polyacetal copolymer.

(Measurement of color tone)
The stabilized polyacetal copolymer was measured with color meter ZE2000 (manufactured by Nippon Denshoku Industries Co., Ltd.), L, a and b were measured, and b was defined as a color tone value. A lower value of b represents less coloring.

(Measurement of foreign matter)
The stabilized polyacetal copolymer was press-molded with a hot press (manufactured by Matsuda Seisakusho) set at 220 ° C. using 180 mm × 180 mm × 2 mm (thickness) as a mold to obtain a molded piece. . About both surfaces of the said molded piece, the number of 0.1 mm or more foreign materials was measured visually using the magnifier. Foreign materials are black, brown, red, yellow, etc., but all were counted.

[Example 1]
(A) To 100 parts by mass of the polyacetal copolymer before terminal stabilization, (B-1) triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate]. 2 parts by mass, (C-1) 0.1 parts by mass of talc were uniformly added and mixed, and a twin-screw extruder with a vent set at 200 ° C. (L / D = 40, where L is the value of the extruder (D-1 represents the diameter of the cylinder of the extruder), and (D-1) 0.8 mass% triethylamine aqueous solution was converted into the amount of nitrogen in the terminal stabilization zone. The solution was liquid-added to 20 ppm, stabilized while degassing under reduced pressure at 90 KPa, and pelletized with a pelletizer. Thereafter, drying was performed at 100 ° C. for 2 hours to obtain a stabilized polyacetal copolymer.
The stabilized polyacetal copolymer was measured for thermal stability, color tone, and foreign matter. The results are shown in Table 1.

[Examples 2-9 and 12-22]
The same operation as in Example 1 was performed except that (B) stabilizer and (C) inorganic filler were changed to the types and amounts shown in Table 1. The results are shown in Tables 1 and 2.

[Examples 10 and 11]
(D-1) Instead of triethylamine aqueous solution, (D-2) triethyl (2-hydroxyethyl) ammonium formate or (D-3) tripropyl (2-hydroxyethyl) ammonium formate as a quaternary ammonium compound (D-2) triethyl (2-hydroxyethyl) ammonium formate diluted with water (1/2) to polyacetal copolymer before terminal stabilization in advance (1/2), or (D- 3) Tripropyl (2-hydroxyethyl) ammonium formate was added to 20 ppm in terms of the amount of nitrogen, and then dried at 100 ° C. for 3 hours to remove moisture. The water content of the mixture of (A) and (D-1) or (D-2) was 30 ppm. Next, each of the mixture of (A) and (D-1) or (D-2) is added to (B-1) triethylene glycol-bis [3- (3-t-butyl-5-methyl-4- Hydroxyphenyl) propionate] 0.2 parts by mass, (C-1) 0.1 parts by mass of talc are uniformly added and mixed, and supplied to a twin-screw extruder with a vent set to 200 ° C. (L / D = 40) The mixture was stabilized while degassing under reduced pressure at 90 KPa, and pelletized with a pelletizer. Thereafter, drying was performed at 100 ° C. for 2 hours to obtain a stabilized polyacetal copolymer.
The stabilized polyacetal copolymer was measured for thermal stability, color tone, and foreign matter. The results are shown in Table 1.

[Comparative Example 1]
(A) The polyacetal copolymer before terminal stabilization is supplied to a twin-screw extruder with a vent set to 200 ° C. (L / D = 40), and (D) 0.8 mass% triethylamine aqueous solution is The liquid was added to 20 ppm in terms of the amount of nitrogen, stabilized while degassing under reduced pressure at 90 KPa, and pelletized with a pelletizer. Thereafter, drying was performed at 100 ° C. for 2 hours to obtain a stabilized polyacetal copolymer.
The stabilized polyacetal copolymer was measured for thermal stability, color tone, and foreign matter. The results are shown in Table 3.

[Comparative Examples 2 and 3]
The same operation as in Example 1 was performed except that (B) a stabilizer and (C) an inorganic filler were added alone. The results are shown in Table 3.

[Comparative Example 4]
(C) An inorganic filler was further added to the polyacetal copolymer after terminal stabilization obtained in Comparative Example 2 to form an extruded pellet.
Specifically, a single screw extruder with a vent (L / D = 24) was set to 200 ° C., and (C) an inorganic filler was added to the pellets of Comparative Example 2 and supplied to the extruder. At this time, the pressure reduction degree of the vent was 90 kPa. The results are shown in Table 3.

  The polyacetal copolymer obtained by the method for producing a polyacetal copolymer of the present invention has industrial applicability in the field of parts such as automobiles, electronic devices, and electric devices.

Claims (6)

  (A) The manufacturing method of a polyacetal copolymer including performing terminal stabilization of the polyacetal copolymer before terminal stabilization in presence of (B) stabilizer and (C) inorganic filler.   2. (A) The polyacetal copolymer before terminal stabilization, (B) stabilizer, (C) inorganic filler and (D) terminal stabilizer are degassed under reduced pressure while being melt-kneaded. A process for producing the polyacetal copolymer described in 1.   (A) Polyacetal copolymer before terminal stabilization, (B) stabilizer, and (C) inorganic filler are melt-kneaded, and then (D) terminal stabilizer is added and melt-kneaded, followed by depressurization under reduced pressure. The method for producing a polyacetal copolymer according to claim 1, wherein   The method for producing a polyacetal copolymer according to any one of claims 1 to 3, wherein (B) the stabilizer is an antioxidant and / or a form catcher agent.   (C) The inorganic filler is 1 or 2 or more selected from calcium carbonate, talc and wollastonite, The method for producing a polyacetal copolymer according to any one of claims 1 to 4.   (C) The average particle diameter of an inorganic filler is 1 micrometer or more, The manufacturing method of the polyacetal copolymer as described in any one of Claims 1-5 characterized by the above-mentioned.