JP2011116862A - Method for producing polyacetal resin composition and polyacetal resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polyacetal resin composition, having excellent long-time continuous extrusion productivity, and capable of effectively reducing thermal decomposition and deterioration of a material. <P>SOLUTION: The method for producing the polyacetal resin composition includes a step for obtaining a polyacetal resin homopolymer (A) having a heating weight loss of 0.1-1.0 mass% when heated for 50 min at 222°C under ≤-500 mmHg of a pressure condition, a step for regulating the water content of an acrylamide polymer (B) containing a structure represented by general formulas (I) and/or (II) so as to be ≤1,500 ppm, a step for regulating the water content of a hydrazide compound (C) so as to be ≤1,500 ppm, and a step for melt-kneading the polyacetal resin homopolymer (A), the acrylamide polymer (B), the hydrazide compound (C) and a hindered phenol-based antioxidant (D). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a polyacetal resin composition and a polyacetal resin composition.

The polyacetal resin is a crystalline resin and is a resin material having excellent rigidity, strength, toughness, slidability, and creep properties.
The use of polyacetal resin covers a wide range such as materials for mechanical parts such as automobile parts, electric / electronic parts and industrial parts.

In the case of continuously producing these various mechanical parts, first, various additives and stabilizers are blended in the polyacetal resin and melt kneaded by an extruder or the like to obtain a polyacetal resin composition. Thereafter, a desired molded article is injection-molded using the obtained pellet of the polyacetal resin composition, and various mechanical parts are continuously produced.
At that time, if continuous production is performed for a long period of time, depending on the temperature and residence time of the extruder or molding machine, the polyacetal resin undergoes thermal decomposition and releases formaldehyde.
The released formaldehyde becomes a carbide by a saccharification reaction (formose reaction) and is mixed in the polyacetal resin composition.
In addition, various additives and stabilizers added in the polyacetal resin are also modified by so-called burning depending on the temperature and residence time of the extruder or molding machine, and these modified (modified) products are polyacetal resin compositions. It mixes in things.
The formaldehyde carbide, additive, and modified stabilizer are also mixed in a molded product using the polyacetal resin composition, and when a polyacetal resin molded product in which these carbide and modified products are mixed is used continuously for a long period of time. The stress at the time of use concentrates on the places where carbides and modified products exist, which becomes a starting point of destruction, and impairs the inherent durability of the polyacetal resin.

Therefore, when continuously producing various mechanical parts using the polyacetal resin composition, the polyacetal resin temperature is lowered to the vicinity of the melting point as much as possible, and further produced under conditions such as suppressing the residence time in the extruder and molding machine, The occurrence of carbides and modified products is suppressed, and the above-described mixing of carbides and modified products is prevented by taking measures such as periodically cleaning the inside of the extruder and molding machine.
Furthermore, the present situation is that a great deal of labor is required for quality control by performing a process inspection such as a visual inspection to check whether foreign matters are mixed in a molded article using the polyacetal resin composition.

  Conventionally, as a method for improving the thermal stability of a polyacetal resin, a method of adding and blending a ternary copolymer polyamide (for example, see Patent Document 1) or a method of adding and blending a poly-β-alanine polymer (for example, , See Patent Document 2.) A method of adding and blending two or more polyamide resins (for example, see Patent Document 3) has been proposed.

Japanese Patent Publication No.34-5440 JP-A-2-247247 JP-A 51-64559

  However, according to the above-mentioned conventionally proposed method, when continuous extrusion production is performed in a short time, the thermal decomposition of the polyacetal resin and the modification of the additive can be suppressed, and a highly durable polyacetal resin composition can be obtained. When extrusion production is performed continuously for a long period of time, it is possible to completely suppress the generation of carbides caused by formaldehyde resulting from thermal decomposition of polyacetal resin, various additives, and modified products caused by stabilizers. Therefore, it is difficult to produce continuously for a long time.

  Therefore, in the present invention, even if extrusion production is carried out continuously for a long time, the thermal decomposition of polyacetal resin and the modification of various additives are effectively suppressed, and practically good mechanical properties and thermal stability. Another object of the present invention is to provide a method for producing a polyacetal resin composition capable of producing a molded article having durability, and a polyacetal resin composition obtained by the production method.

As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have found that a specific moisture content is added to the polyacetal resin homopolymer (A) that specifies the weight loss by heating under a predetermined temperature, time, and pressure conditions. The polyacetal resin composition obtained by adding an amount of the acrylamide polymer (B), the hydrazide compound (C), and further the hindered phenolic antioxidant (D) and melt-kneading the above-mentioned conventional technology The present inventors have found that the above problems can be solved and have reached the present invention.
That is, the present invention is as follows.

[1]
Polyacetal resin homopolymer (A),
An acrylamide polymer (B) having a structure represented by the following general formula (I) and / or (II):
Hydrazide compound (C),
And hindered phenol antioxidants (D)
A process for producing a polyacetal resin composition comprising:
Obtaining a polyacetal resin homopolymer (A) having a weight loss by heating of 0.1 to 1.0 mass% when heated at 222 ° C. for 50 minutes under a pressure condition of −500 mmHg or less;
Adjusting the water content of the acrylamide polymer (B) to 1500 ppm or less;
Adjusting the water content of the hydrazide compound (C) to 1500 ppm or less;
Melting and kneading the polyacetal resin homopolymer (A), the acrylamide polymer (B), the hydrazide compound (C), and the hindered phenol-based antioxidant (D);
The manufacturing method of the polyacetal resin composition which has these.

[2]
The method for producing a polyacetal resin composition according to [1], wherein the acrylamide polymer (B) has an average particle size of 0.1 to 10 μm.

[3]
The total amount (B + C) of the addition amount of the acrylamide polymer (B) and the hydrazide compound (C) is 0.001 to 1.0 part by mass with respect to 100 parts by mass of the polyacetal resin homopolymer (A). The manufacturing method of the polyacetal resin composition as described in [1] or [2].

[4]
The polyacetal resin according to any one of [1] to [3], wherein a blending ratio (B) / (C) of the acrylamide polymer (B) and the hydrazide compound (C) is 1 to 25. A method for producing the composition.

[5]
The polyacetal resin composition obtained by the manufacturing method of the polyacetal resin composition as described in any one of said [1] thru | or [4].

  According to the present invention, even when extrusion production is carried out continuously for a long time, the thermal decomposition of the polyacetal resin and the modification of various additives can be effectively suppressed, and practically good mechanical properties, thermal stability, The manufacturing method of the polyacetal resin composition which can manufacture the molded article which has durability, and the polyacetal resin composition obtained by the said manufacturing method can be provided.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described.
The present invention is not limited to the following description, and various modifications can be made within the scope of the gist thereof.

[Method for producing polyacetal resin composition]
In this embodiment, polyacetal resin homopolymer (A), acrylamide polymer (B), hydrazide compound (C) having a structure represented by the following general formula (I) and / or (II), and a hindered phenol type A polyacetal resin composition containing the antioxidant (D) is produced.

  The production method of this embodiment is a step of obtaining a polyacetal resin homopolymer (A) having a weight loss of 0.1 to 1.0% by mass when heated at 222 ° C. for 50 minutes under a condition of −500 mmHg or less. And adjusting the water content of the acrylamide polymer (B) to 1500 ppm or less, adjusting the water content of the hydrazide compound (C) to 1500 ppm or less, the polyacetal resin homopolymer (A), and A step of melt-kneading the acrylamide polymer (B), the hydrazide compound (C), and the hindered phenol-based antioxidant (D).

The raw material used for the manufacturing method of the polyacetal resin composition of this embodiment is demonstrated.
(Polyacetal resin homopolymer (A))
The polyacetal resin homopolymer (A) has an oxymethylene group in the main chain, and the weight loss by heating when heated at 222 ° C. for 50 minutes under a reduced pressure condition of −500 mmHg or less as described later. Is preferably in the range of 0.1 to 1.0% by mass, the terminal group of the polymer preferably has an ester group or ether group structure.
The heating weight loss amount under the above conditions is preferably 0.1 to 0.8% by mass, more preferably 0.1 to 0.5% by mass.
When the polyacetal resin homopolymer (A) has a weight loss by heating in the above-mentioned conditions in the range of 0.1% by mass to 1.0% by mass, the polyacetal resin composition produced using this polyacetal resin homopolymer, When performing various molding processes, excellent extrusion productivity can be realized. Specifically, formaldehyde generated by thermal decomposition of the polyacetal resin reacts with the hydrazide compound (C). This reaction product has a compatibilizing effect between the polyacetal resin homopolymer (A) and the acrylamide polymer (B), and improves the dispersibility of the acrylamide polymer (B).
By improving the dispersibility of the acrylamide polymer (B), the adhesion of the acrylamide polymer (B) to the extruder screw is reduced, and further, aggregation of the acrylamide polymer (B) itself is suppressed. The generation amount of denatured products and aggregates due to the burning of the coalescence decreases, and the generation amount of carbides due to formaldehyde decreases due to the hydrazide compound (C) capturing formaldehyde.
As a result, when the polyacetal resin composition is continuously extruded and produced for a long period of time, an increase in the resin pressure of the extruder die portion can be effectively suppressed, and the extrusion productivity of the polyacetal resin composition can be remarkably improved. .
Furthermore, the amount of carbides and modified products mixed in the molded product of the polyacetal resin composition can be reduced, and a molded product made of polyacetal resin having excellent long-term durability can be provided.

When the weight loss by heating in the above conditions of the polyacetal resin homopolymer (A) exceeds 1.0% by mass, formaldehyde exceeding the scavenging ability of the hydrazide compound (C) is generated by pyrolysis, and the carbide derived from formaldehyde (Foreign matter) increases, the extruder die pressure due to clogging of the extruder screen mesh increases (screen replacement frequency increases), and the extrusion productivity of the polyacetal resin composition decreases.
Furthermore, a carbide or modified product that could not be removed is mixed in the molded product of polyacetal resin, and a molded product of polyacetal resin excellent in long-term durability cannot be provided.
On the other hand, when the weight loss by heating under the above conditions is less than 0.1% by mass, there is little reaction product of formaldehyde and hydrazide compound (C), and the acrylamide polymer (B) is used in an extruder or molding machine. It adheres to the screw, and burning (modified product) is generated due to the temperature at the time of extrusion, and the acrylamide polymer itself aggregates.
This modified material clogs the mesh of the extruder screen, increases the die pressure of the extruder, and makes it difficult to continuously produce for a long time.
There is also a problem that a modified product that cannot be removed is mixed in the polyacetal resin molded product, and a polyacetal resin molded product with excellent long-term durability cannot be provided.

(Method for producing polyacetal resin homopolymer (A))
As described above, the polyacetal resin homopolymer (A) having a weight loss by heating in the range of 0.1 to 1.0% by mass when heated at 222 ° C. for 50 minutes under a reduced pressure of −500 mmHg or less. The original crude polyacetal resin homopolymer can be produced by a conventionally known method.
For example, formaldehyde as a monomer, a chain transfer agent (molecular weight regulator) and a polymerization catalyst are fed to a polymerization reactor filled with a hydrocarbon solvent, and a crude polyacetal resin homopolymer is obtained by slurry polymerization.
In the obtained crude polyacetal resin homopolymer, the terminal group of the polymer is thermally unstable, so this unstable terminal group is blocked with an esterifying agent or an etherifying agent, and the polymer terminal group is blocked and stabilized. .
Specifically, since the raw material formaldehyde, the chain transfer agent, and the hydrocarbon polymerization solvent contain a component capable of chain transfer (a component that generates unstable terminal groups), such as water, methanol, and formic acid, First, the content of these chain transferable components is adjusted, and the crude polyacetal resin homopolymer is polymerized.
The content of the component capable of chain transfer at this time is preferably in the range of 1 to 1000 ppm, more preferably 1 to 500 ppm, and still more preferably 1 to 300 ppm with respect to formaldehyde as a monomer.
By adjusting the amount of the component capable of chain transfer to the above range, a polyacetal resin homopolymer having a weight loss by heating of 0.1 to 1.0% by mass under the above conditions can be easily obtained.

The molecular weight of the polyacetal resin homopolymer (A) can be adjusted by chain transfer using carboxylic anhydride or carboxylic acid.
As the molecular weight regulator, propionic anhydride and acetic anhydride are particularly preferable, and acetic anhydride is more preferable.
The introduction amount of the molecular weight modifier can be determined by adjusting the molecular weight according to the intended characteristics, and the melt flow rate of the polyacetal resin homopolymer (A): MFR value (based on ISO 1133) is 0.1 to 100 g. / 10 minutes, preferably 1.0 g / 10 minutes to 70 g / 10 minutes.

As the polymerization catalyst, an anionic polymerization catalyst is preferable, and an onium salt polymerization catalyst represented by the following general formula (III) is more preferable.
Among the onium salt polymerization catalysts, quaternary phosphonium salt compounds such as tetraethylphosphonium iodide and tributylethylphosphonium iodide, and quaternary ammonium salts such as tetramethylammonium bromide and dimethyl distearyl ammonium acetate. System compounds are preferred. The addition amount of these quaternary phosphonium salt compounds and quaternary ammonium salt compounds is 0.0003 to 0.01 mol, preferably 0.0008 to 0.005 mol, more preferably, to 1 mol of formaldehyde. 0.001 to 0.003 mol.

[R ₁ R ₂ R ₃ R ₄ M] ⁺ X ⁻ (III)
(In the above formula (III), R ₁ , R ₂ , R ₃ and R ₄ each independently represents an alkyl group, M represents an element having a lone electron pair, and X represents a nucleophilic group.)

The hydrocarbon polymerization solvent is not particularly limited as long as it does not react with formaldehyde, but in general, pentane, isopentane, hexane, cyclohexane, heptane, octane, nonane, decane, benzene, etc. These solvents can be used.
These hydrocarbon solvents can be used in combination of two or more, but hexane is particularly preferred.

  In addition, the polymerization apparatus for producing the crude polyacetal resin homopolymer is not particularly limited as long as it is an apparatus that can simultaneously supply the monomer formaldehyde, the chain transfer agent (molecular weight regulator), the polymerization catalyst and the hydrocarbon polymerization solvent. However, a continuous polymerization apparatus is preferable from the viewpoint of productivity.

The crude polyacetal resin homopolymer obtained by the above method is a polyacetal resin homopolymer having a weight loss amount of 1.0% by mass or more when heated at 222 ° C. for 50 minutes under a pressure of −500 mmHg or less. In order to obtain the polyacetal resin homopolymer (A) used in the method for producing the polyacetal resin composition of this embodiment, it is preferable to block and stabilize the end groups of the polymer with an esterifying agent.
The crude polyacetal resin homopolymer has a terminal stabilization method in which a crude polyacetal resin homopolymer, an esterifying agent, and an esterification catalyst are charged into a terminal stabilization reactor filled with a hydrocarbon solvent, respectively, and the crude polyacetal resin homopolymer is introduced. Stabilizes the unstable ends of the polymer.
The reaction temperature at this time is 130 to 155 ° C., and the reaction time is preferably 1 to 100 minutes, more preferably the reaction temperature is 135 to 155 ° C. and the reaction time is 5 to 100 minutes, more preferably the reaction temperature. Is 140 to 155 ° C., and the reaction time is 10 to 100 minutes.
The polyacetal resin homopolymer whose end groups are stabilized under the above conditions is filled with nitrogen gas adjusted to 100 to 150 ° C. using a dryer such as a hot air drier or a vacuum drier to remove moisture and dry. To do.
The drying time at this time is appropriately selected and adjusted so that the amount of water contained in the polyacetal resin homopolymer is 500 ppm or less.
Specifically, it is preferably in the range of 1 to 100 hours, more preferably in the range of 1 to 80 hours, and still more preferably in the range of 1 to 50 hours.
As described above, by controlling and adjusting the amount of water contained in the polyacetal resin homopolymer, it is possible to prevent the migration of moisture to the acrylamide polymer (B) and hydrazide compound (C) described later, and these are included in these. The amount of water can also be adjusted, improving the dispersibility of the acrylamide polymer (B), improving the dispersibility of the acrylamide polymer (B), reducing the adhesion to the extruder screw, and further the acrylamide polymer (B) Suppression of its own aggregates can be achieved and the extrusion productivity of the polyacetal resin composition can be improved.

The amount of water contained in the polyacetal resin homopolymer (A) can be generally measured using a method for quantifying the amount of water in the liquid component or solid component, for example, the Karl Fischer (coulometric titration) method.
The amount of water contained in the polyacetal resin homopolymer (A) is preferably 500 ppm or less, more preferably 300 ppm or less, and still more preferably 100 ppm or less.

As the esterifying agent that blocks and stabilizes the end group of the crude polyacetal resin homopolymer, an acid anhydride represented by the following general formula (IV) can be used.
Specifically, benzoic anhydride, succinic anhydride, maleic anhydride, glutaric anhydride, phthalic anhydride, propionic anhydride, and acetic anhydride are preferable, and acetic anhydride is preferable.
These esterifying agents may be used alone or in combination of two or more.
R ₅ COOCOR ₆ (IV)
(In the above formula (IV), R ₅ and R ₆ each independently represents an alkyl group. R ₅ and R ₆ may be the same or different.)

The esterification catalyst is preferably an alkali metal salt of a carboxylic acid having 1 to 18 carbon atoms, and the addition amount thereof is appropriately selected and charged within a range of 1 to 1000 ppm with respect to the polyacetal resin homopolymer.
The alkali metal salt of a carboxylic acid having 1 to 18 carbon atoms is, for example, carboxylic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caprylic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, These are myristic acid, palmitic acid, margaric acid, and stearic acid. The alkali metals are lithium, sodium, potassium, rubidium, and cesium, and these are carboxylic acid metal salts composed of these carboxylic acids and alkali metals. Among these carboxylic acid metal salts, lithium acetate, sodium acetate, and potassium acetate are preferable.

On the other hand, the end group of the above-mentioned crude polyacetal resin homopolymer can be blocked by etherification and stabilized.
Etherifying agents in this case are orthoesters of aliphatic or aromatic acids with aliphatic, alicyclic or aromatic alcohols such as methyl or ethyl orthoformate, methyl or ethyl orthoacetate and methyl or ethyl Lewis acid forms such as orthobenzoates and orthocarbonates such as ethyl orthocarbonate, medium strength organic acids such as p-toluenesulfonic acid, acetic acid and odorous acid, medium strength mineral acids such as dimethyl and diethyl sulfate It can obtain using the catalyst of.
Solvents used for the etherification reaction include low boiling point aliphatics such as pentane, hexane, cyclohexane and benzene, alicyclic and aromatic hydrocarbons, halogenated lower aliphatics such as methylene chloride, chloroform and carbon tetrachloride, etc. Organic solvents are preferred.

(Measurement method of heating weight loss of polyacetal resin homopolymer (A))
Next, a method for measuring the weight loss by heating of the polyacetal resin homopolymer (A) used in this embodiment will be described.
The method of measuring the weight loss by heating is as follows. First, the powdered polyacetal resin homopolymer (A) is tableted with a tablet molding machine, cut into granules of about 1 mm square or less from this tablet, and placed in a test tube. In
At this time, the input amount of the polyacetal resin homopolymer (A) is determined in the range of 10 to 50 mg.
Thereafter, the pressure is reduced for 10 minutes at a reduced pressure of −500 mmHg or less, and then immersed in an oil bath set at 222 ° C. for 50 minutes.
After the heating is completed, the weight of the entire test tube is measured, and the weight loss by heating is determined from the weight difference before and after heating.
The polyacetal resin homopolymer (A) having a weight loss by heating of 0.1 to 1.0% by mass can be produced by appropriately selecting the polymerization and terminal stabilization conditions of the polyacetal resin homopolymer.

(Acrylamide polymer (B))
The acrylamide polymer (B) used in the method for producing the polyacetal resin composition of the present embodiment is an acrylamide polymer having a structure represented by the following general formula (I) and / or (II). In addition, the acrylamide polymer which introduce | transduced the monomer which has vinyl groups other than acrylamide as a copolymerization component may be sufficient.
Preferably, it is an acrylamide polymer containing a primary amide group in an amount of 30 to 70 mol% and introducing a monomer having a vinyl group other than acrylamide as a copolymerization component, containing 1500 ppm or less of water, and having an average particle size An acrylamide polymer having a diameter of 0.1 to 10 μm.
By using this acrylamide polymer (B), the polyacetal resin composition obtained by the production method of the present embodiment is excellent in extrusion productivity.

(Method for producing acrylamide polymer (B))
The acrylamide polymer (B) can be produced by polymerization of acrylamide or polymerization of acrylamide and a monomer having a vinyl group other than acrylamide using an alkali earth metal alcoholate as a catalyst.
The monomer having a vinyl group other than acrylamide constituting the acrylamide polymer (B) is a monomer having one or two vinyl groups.
Monomers having one vinyl group are n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, cesyl methacrylate, pentadecyl methacrylate, stearyl methacrylate, behenyl methacrylate, Hydroxypropyl methacrylate, polypropylene glycol methacrylate, polyethylene glycol methacrylate and the like.
Monomers having two vinyl groups are divinylbenzene, ethylene bisacrylamide, N, N′-methylenebisacrylamide and the like.
Among these monomers having a vinyl group, N, N′-methylenebisacrylamide is preferable.
The introduction amount of the monomer having a vinyl group is preferably 0.05 to 20% by mass with respect to the total amount of the acrylamide component and the monomer having a vinyl group.
By copolymerizing with these vinyl group-containing monomers (providing a crosslinked structure), the extrusion productivity of the polyacetal resin composition can be further improved.
Examples of the polymerization solvent used in the polymerization of the acrylamide polymer (B) include aromatic hydrocarbons such as benzene, toluene and xylene, and halogenated aromatic hydrocarbons such as chlorobenzene and o-dichlorobenzene. A polymerization catalyst is added to dehydrated and purified acrylamide and heated in an inert gas atmosphere for production.
The polymerization temperature is preferably 70 to 150 ° C, more preferably 80 to 130 ° C.

The acrylamide polymer (B) produced under the conditions described above contains water generated by a polymerization solvent and a polymerization reaction.
Therefore, for example, it is preferable to adjust the moisture content by performing a drying process using a dryer such as a hot air dryer or a vacuum dryer.
When drying using a vacuum dryer, the drying temperature is, for example, 50 to 150 ° C., the degree of vacuum is, for example, −600 mmHg or less, and the drying time is appropriately selected until the target moisture content is reached.
When drying using a hot air dryer, it is preferable to adjust the temperature in the dryer by sealing nitrogen gas controlled to 50 to 150 ° C. to remove the polymerization solvent and moisture, and then dry.
Among these drying conditions, a method of drying using a vacuum dryer is preferable, and it is more preferable that the degree of vacuum is −600 mmHg and the drying time is 10 to 30 hours in a temperature range of 50 to 70 ° C.
In the present embodiment, the moisture content of the acrylamide polymer (B) is adjusted to 1500 ppm or less. As a result, aggregation of the acrylamide polymers (B) can be prevented, and the effect of improving the dispersibility in the polyacetal resin homopolymer (A) and reducing the adhesion to the extruder screw can be obtained, and the polyacetal resin composition can be produced by extrusion. Can be improved.

The amount of water contained in the acrylamide polymer (B) can generally be measured using a method for quantifying the amount of water in the liquid component or solid component, for example, the Karl Fischer (coulometric titration) method.
The amount of water contained in the acrylamide polymer (B) is 1500 ppm or less, preferably 1000 ppm or less.
When the water content of the acrylamide polymer (B) is in the above range, a polyacetal resin composition having excellent extrusion productivity can be provided.

It is preferable that the average particle diameter of the acrylamide polymer (B) used when implementing the manufacturing method of the polyacetal resin composition of this embodiment is 0.1-10 micrometers.
The acrylamide polymer (B) can be pulverized using a pulverizer such as a jet mill or a ball mill to adjust the target average particle size.
The average particle diameter of the acrylamide polymer (B) can be measured by dispersing the acrylamide polymer (B) in alcohol and charging this suspension in a particle size measuring device. Specifically, it can measure by the method described in the Example mentioned later.
The average particle size of the acrylamide polymer (B) measured by the above method is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and still more preferably 0.1 to 3 μm.
When the average particle diameter of the acrylamide polymer (B) is within the above range, a polyacetal resin composition having excellent extrusion productivity can be obtained.

As described above, the acrylamide polymer (B) preferably contains 30 to 70 mol% of primary amide groups, but the primary amide group quantification method of this acrylamide polymer (B). Will be described.
First, an acrylamide polymer (B) and a 40% by mass potassium hydroxide aqueous solution are added to a flask equipped with a stirrer, and heated at 105 to 110 ° C. for 20 minutes while stirring to hydrolyze the primary amide group with ammonia. .
Next, the flask contents are cooled to 50 ° C. or lower, methanol is added, and ammonia is extracted together with methanol.
The extract can be absorbed in a 0.1 N aqueous sulfuric acid solution and neutralized with a 0.1 N aqueous sodium hydroxide solution using methyl red as an indicator to quantify primary amide groups.
The acrylamide polymer (B) produced by the above method is put into a sealed container or bag and managed for the purpose of blocking moisture in the atmosphere.

(Hydrazide compound (C))
The hydrazide compound (C) used in the method for producing the polyacetal resin composition of the present embodiment is a carboxylic acid mono / or dihydrazide compound or an alkyl group synthesized by reaction of a carboxylic acid (an aromatic ring or an alicyclic ring) with hydrazine. It is a substituted mono / or dihydrazide compound and is a hydrazide compound having a water content of 1500 ppm or less.

  The carboxylic acid constituting the carboxylic acid mono / or dihydrazide compound includes formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid , Margaric acid, stearic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, naphthalic acid, Examples include salicylic acid, gallic acid, melicic acid, cinnamic acid, pyruvic acid, lactic acid, malic acid, citric acid, fumaric acid, maleic acid, aconitic acid, amino acids, and nitrocarboxylic acid.

Specific examples of carboxylic acid mono (di) hydrazide compounds include carbodihydrazine, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, lauric acid dihydrazide, malic acid dihydrazide, Tartaric acid dihydrazide, propionic acid monohydrazide, lauric acid monohydrazide, stearic acid monohydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthalic acid dihydrazide, p-hydroxybenzoic hydrazine, p-hydroxybenzoic Hydrazine, 1,4-cyclohexanedicarboxylic acid dihydrazine, acetohydrazide, acrylohydrazide, maleic acid dihydrazide, fumaric acid dihydr Hydrazide, benzohydrazide, nicotinonitrile hydrazide, isonicotinohydrazide, isobutyl hydrazine, and hydrazide oleate.
In particular, adipic acid dihydrazide, sebacic acid dihydrazide, lauric acid hydrazide, lauric acid dihydrazide, stearic acid hydrazide, and stearic acid dihydrazide are preferable, and adipic acid dihydrazide and sebacic acid dihydrazide are more preferable.

The above various hydrazide compounds contain moisture used in the production process, and when added to and mixed with the polyacetal resin homopolymer (A), for example, using a dryer such as a hot air dryer or a vacuum dryer. Remove and adjust moisture content.
The drying temperature at this time is preferably 100 to 150 ° C., and the drying time is appropriately selected until a desired water content is obtained, and is adjusted to a water content of 1500 ppm or less, preferably 1000 ppm or less. .
When the water content contained in the hydrazide compound (C) is in the above range, excellent extrusion productivity can be realized in the target polyacetal resin composition.

The water content of the hydrazide compound (C) can be generally measured using a method for quantifying the water content of a liquid component or a solid component, for example, a Karl Fischer (coulometric titration) method.
The hydrazide compound (C) is introduced and managed in a sealed container or bag for the purpose of blocking moisture in the atmosphere. Thereby, adsorption | suction of a water | moisture content can be prevented.

  By adding and blending the acrylamide polymer (B) and the hydrazide compound (C) obtained as described above to the polyacetal resin homopolymer (A), a polyacetal resin composition having excellent extrusion productivity can be obtained.

When the amount of water contained in the acrylamide polymer (B) and the hydrazide compound (C) exceeds 1500 ppm, the reaction between formaldehyde released from the polyacetal resin homopolymer (A) and the hydrazide compound (C) sufficiently proceeds. Without compatibility, the compatibility between the polyacetal resin homopolymer (A) and the acrylamide polymer (B) is reduced, and the acrylamide polymer (B) tends to adhere to the extruder screw. It becomes a modified product depending on the residence time, and aggregates due to aggregation of the acrylamide polymer (B) itself increase, thereby inhibiting the continuous productivity of the polyacetal resin composition.
Furthermore, these modified products and aggregates are mixed in the polyacetal resin composition, and the long-term durability inherent in the polyacetal resin is also reduced.
Therefore, by adjusting the amount of water contained in the acrylamide polymer (B) and the hydrazide compound (C) to 1500 ppm or less, formaldehyde and the dolazide compound (C) react easily, and this reaction product is a polyacetal resin homopolymer. The compatibility of (A) and acrylamide polymer (B) is improved, and the polyacetal resin composition excellent in extrusion productivity is obtained.

(Amount of addition of acrylamide polymer (B) and hydrazide compound (C))
The addition amount of the acrylamide polymer (B) and the hydrazide compound (C) is such that the total amount (B + C) of the acrylamide polymer (B) and the hydrazide compound (C) is 100 parts by mass of the polyacetal resin homopolymer (A). It is preferable that it is the range of 0.001-1.0 mass part with respect to it, More preferably, it is 0.01-0.6 mass part, More preferably, it is 0.1-0.3 mass part, These addition amounts In the range of the total amount, the blending ratio (B / C) of the acrylamide polymer and the hydrazide compound is appropriately selected as will be described later, thereby improving the extrusion productivity of the polyacetal resin composition, and the polyacetal A molded product made of polyacetal resin having the long-term durability inherent in the resin can be provided.

(Blending ratio of acrylamide polymer (B) and hydrazide compound (C))
In addition to the amount of water contained in the acrylamide polymer (B) and the hydrazide compound (C), the blending ratio of the acrylamide polymer (B) and the hydrazide compound (C) is also important for realizing excellent extrusion productivity. is there.

The blending ratio (B) / (C) of the acrylamide polymer (B) and the hydrazide compound (C) is preferably in the range of 1 to 25, more preferably in the range of 1 to 20, and still more preferably in the range of 1 to 15. It is.
When the blending ratio of the acrylamide polymer (B) and the hydrazide compound (C) is within the above range, the extrusion productivity of the target polyacetal resin composition can be improved and the inherent long-term property of the polyacetal resin can be improved. A molded article made of polyacetal resin having durability can be provided.

When the blending ratio (B / C) of the acrylamide polymer (B) and the hydrazide compound (C) exceeds 25, the amount of the reaction product of formaldehyde and the hydrazide compound (C) is small, and the polyacetal resin homopolymer (A) and acrylamide Compatibility with polymer (B) does not improve, acrylamide polymer (B) itself agglomerates, sticks to the extruder screw, and the amount of modified product due to burning increases, impairing the extrusion productivity of polyacetal resin composition To do.
In addition, aggregates and modified products are mixed into the polyacetal resin composition, and the inherent long-term durability of the polyacetal resin is also reduced.
On the other hand, when the blending ratio (B / C) of the acrylamide polymer (B) and the hydrazide compound (C) is less than 1, the excessively added hydrazide compound (C) is the main chain decomposition of the polyacetal resin homopolymer (A). The amount of carbide caused by formaldehyde generated by decomposition is increased and the extrusion productivity of the polyacetal resin composition is inhibited.
In addition, the inherent long-term durability of the polyacetal resin also decreases.
That is, when the blending ratio (B) / (C) of the acrylamide polymer (B) and the hydrazide compound (C) is in the range of 1 to 25, the polyacetal resin homopolymer (A) and the acrylamide polymer (B) The reaction product required to improve the compatibility of the acrylamide polymer (B) itself is aggregated, adhered to the extruder screw, the amount of the modified product due to burning is reduced, and the extrusion productivity of the polyacetal resin composition Can be improved. Moreover, since the mixing amount of these aggregates and modified products is small, the inherent long-term durability of the polyacetal resin is also improved.

(Hindered phenolic antioxidant (D))
As the hindered phenolic antioxidant (D) used in the method for producing the polyacetal resin composition of the present embodiment, a hindered phenolic antioxidant represented by the following general formula (1) can be used.

In the general formula (1), R ₇ and R ₈ are a hydrogen atom or an aliphatic hydrocarbon having 1 to 6 carbon atoms, and R ₉ is an aliphatic hydrocarbon or an aliphatic hydrocarbon having an ether bond. .
n corresponds to the valence of R ₉ .

Specific examples of the hindered phenol-based antioxidant (D) 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-) t-butyl-4-hydroxyphenyl) -propionate), triethylene glycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate), tet Kis- (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate methane, 3,9-bis (2- (3- (3-t-butyl-4 -Hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl) 2,4,8,10-tetraoxaspiro (5,5) undecane, N, N'-bis-3- (3 ', 5'-di-t-butyl-4-hydroxyphenol) priionyl hexamethylenediamine, N, N'-tetramethylenebis-3- (3'-methyl-5'-t-butyl-4-hydroxyphenol) Propionyldiamine, N, N′-bis- (3- (3,5-di-t-butyl-4-hydroxyphenol) propionyl) hydrazine, N-salicyloyl-N′-salicylidenehydrazine, 3- (N— Salicy Roy A - (butyl-4-hydroxyphenyl) propionyloxy 2- (3- (3,5-di) ethyl) Oxyamide etc.) amino-1,2,4-triazole, N, N'-bis.
Among the hindered phenolic antioxidants, triethylene glycol-bis- (3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate), tetrakis- (methylene-3- (3 ′ , 5'-di-t-butyl-4'-hydroxyphenyl) propionate methane is preferred.

  The hindered phenol-based antioxidant (D) is preferably used in a range of 0.05 to 3 parts by mass, and in a range of 0.05 to 1 part by mass with respect to 100 parts by mass of the polyacetal resin (A). It is more preferable to use in the range of 0.1 to 0.5 parts by mass.

Moreover, the said hindered phenolic antioxidant (D) manages and adjusts a moisture content by methods, such as a hot-air drying and vacuum drying, like an acrylamide polymer (B) and a hydrazide compound (C). It is preferable.
Specifically, the amount of water contained in the hindered phenolic antioxidant (D) is removed and adjusted using a dryer such as a hot air dryer or a vacuum dryer, so that the water content is 500 ppm or less. It is preferable.
The drying temperature and time are in the range of 20 ° C. to 50 ° C., and the drying time is appropriately selected until the target moisture content is reached, and the moisture content is preferably 500 ppm or less, more preferably. Is 300 ppm or less, more preferably in the range of 100 ppm or less.
As a method for quantifying the amount of water contained in the hindered phenol antioxidant (D), a method for quantifying the amount of water of a liquid component or a solid component, for example, a Karl Fischer (coulometric titration) method can be applied.
The hindered phenolic antioxidant (D) produced by this method is put into a sealed container or bag and managed for the purpose of blocking moisture in the atmosphere. By this method, the amount of water contained in the hindered phenol-based antioxidant can be adjusted.

(Process for producing a polyacetal resin composition)
In the method for producing a polyacetal resin composition in the present embodiment, the polyacetal resin homopolymer (A) described above, an acrylamide polymer (B) having a structure represented by the following general formula (I) and / or (II), and a hydrazide compound A polyacetal resin composition containing (C) and a hindered phenol antioxidant (D) is produced.

As the polyacetal resin homopolymer (A), a polyacetal resin homopolymer (A) heated at 222 ° C. for 50 minutes under a condition of −500 mmHg or less and having a weight loss by heating of 0.1 to 1.0% by mass. Use.
As said acrylamide polymer (B), what adjusted the water content to 1500 ppm or less as mentioned above is used.
As the hydrazide compound (C), one having a water content adjusted to 1500 ppm or less as described above is used.
By melt-kneading these polyacetal resin homopolymer (A), the acrylamide polymer (B), the hydrazide compound (C), and further the hindered phenol antioxidant (D). A polyacetal resin composition is obtained.

  Specifically, the acrylamide polymer (B), the hydrazide compound (C), and the hindered phenol antioxidant (D) are added to the polyacetal resin homopolymer (A) and melt-kneaded. . Thereby, the polyacetal resin composition excellent in extrusion productivity is obtained.

Specifically, with respect to the addition blending method of the acrylamide polymer (B), the hydrazide compound (C), and the hindered phenol antioxidant (D), first, the stirring type mixing filled with the polyacetal resin homopolymer (A) Acrylamide polymer (B), hydrazide compound (C), hinder placed in a sealed container (bag) in a machine (for example, a stirring mixer such as a Henschel mixer, a cone blender or a planetary motion type stirring mixer) A predetermined amount of dephenol antioxidant (D) is taken out and charged into a stirring mixer.
Next, nitrogen gas is sealed in a stirring mixer and brought into a pressurized state. The pressure of the stirring mixer at this time is preferably 1 to 20 kPa.
Thereafter, stirring and mixing are performed in a state where the pressurized state is maintained.

As for the stirring and mixing conditions, it is preferable to control the rotation speed of the stirring mixer and the stirring and mixing time so that the stirring temperature is in the range of room temperature to 100 ° C.
Specifically, the rotational speed during stirring and mixing is preferably 1 to 50 rpm, and the stirring and mixing time is preferably 1 to 100 hours.
By stirring and mixing under the conditions described above, aggregation of the acrylamide polymer (B) itself can be prevented, and a polyacetal resin composition excellent in extrusion productivity can be obtained.

The stirring mixer is not particularly limited as long as it is an apparatus capable of stirring and mixing under the above-described stirring conditions. Preferably, the stirring mixer can be stirred at a low rotational speed like a planetary motion type stirring mixer and dried. Possible stirring mixers are preferred.
The purpose of maintaining the pressure during stirring and mixing in a pressurized state of 1 to 20 kPa as described above is to block moisture present in the atmosphere from the stirring mixture.
By blocking moisture in the air, the amount of water contained in the acrylamide polymer (B) and the hydrazide compound (C) can be adjusted, and formaldehyde and hydrazide generated by thermal decomposition of the polyacetal resin homopolymer (A) The reaction with the compound (C) occurs easily at the time of melt kneading, the dispersibility of the acrylamide polymer (B) is improved, the dispersibility of the acrylamide polymer (B) is further improved, and the acrylamide polymer (B) Adhesion to the extruder screw can be reduced, preventing aggregation of the acrylamide polymer (B) itself, and reducing the amount of denatured matter (foreign matter) due to burning of the acrylamide polymer. In addition, since the hydrazide compound (C) captures formaldehyde, the amount of generated carbide (foreign matter) due to formaldehyde is reduced.

As described above, the pressure during stirring and mixing is controlled as described above, and the moisture present in the atmosphere is blocked from the stirring mixture, thereby eliminating clogging of the screen mesh of the extruder, screen replacement frequency and cleaning of the extruder. The frequency is reduced and the continuous production of the polyacetal resin composition is significantly improved.
Furthermore, the mixing of foreign substances can be reduced, and a polyacetal resin molded product excellent in long-term durability can be provided by producing various molded products using such a polyacetal resin composition.

(Other additives (E))
In the method for producing the polyacetal resin composition of the present embodiment, other than the polyacetal homopolymer (A), the acrylamide polymer (B), the hydrazide compound (C), and the hindered phenol-based antioxidant (D) that are the raw materials described above. In addition, conventionally known additives and stabilizers can be added as long as the effects of the present invention are not impaired.
Examples include formaldehyde scavengers such as polyamide polymers, ultraviolet absorbers, light stabilizers, polyalkylene glycol plasticizers, ester release agents, pigments, inorganic and organic various reinforcing materials, and the like. These conventionally known additives and stabilizers can be used alone or in combination.
In addition, these additives and stabilizers should also be controlled and adjusted by a method such as drying, like the acrylamide polymer (B), hydrazide compound (C), and hindered phenol antioxidant (D). Is preferred.
The amount of water contained in these additives and stabilizers is preferably in the range of 500 ppm or less, more preferably 300 ppm or less, and even more preferably in the range of 100 ppm or less.
The water content of the additive and stabilizer can be controlled and adjusted according to the drying temperature and the drying temperature.
Further, for the purpose of blocking moisture in the atmosphere, it is preferable to put it in a sealed container or bag and manage it.

The polyamide polymer as the formaldehyde scavenger is a copolymer polyamide obtained by polycondensation of lactams, diamines, dicarboxylic acids, ω-aminocarboxylic acids, alone or in a mixture of two or more, A polyamide polymer having a melting point of 140 to 230 ° C. is preferred.
Specific examples of the polyamide polymer include polyamide 6, polyamide 11, polyamide 12, polyamide 610, polyamide 612, polyamide 6/612, polyamide 6/66/610, and the like.

As the weather resistance (light) stabilizer, a benzotriazole ultraviolet absorber, an oxalic anilide ultraviolet absorber, and a hindered amine light stabilizer are preferable.
Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- [2′-hydroxy-3,5-di-t-butyl-phenyl) benzo Triazole, 2- [2′-hydroxy-3,5-di-isoamyl-phenyl) benzotriazole, 2- [2′-hydroxy-3,5-bis- (α, α-dimethylbenzyl) phenyl] -2H— And benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole, and the like. Preferably 2- [2′-hydroxy-3,5-bis- (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3,5-di-t-butyl- Phenyl) benzotriazole.

  Examples of the oxalic anilide-based ultraviolet absorber include 2-ethoxy-2′-ethyloxalic acid bisanilide, 2-ethoxy-5-tert-butyl-2′-ethyloxalic acid bisanilide, 2- And ethoxy-3′-dodecyloxalic acid bisanilide. These substances may be used alone or in combination of two or more.

Examples of hindered amine light stabilizers include 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2, 2, 6,6-tetramethylpiperidine, 4- (phenylacetoxy) -2,2,6,6-tetramethylpiperidine 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy-2,2 , 6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2, 2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4- (ethylcarbamo Yloxy) -2,2,6,6-tetramethylpiperidine, 4- (cyclohexylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6 -Tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidine) -carbonate, bis (2,2,6,6-tetramethyl-4-piperidyl) -oxalate, bis (2,2 , 6,6-tetramethyl-4-piperidyl) -malonate, bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, bis (2,2,6,6-tetramethyl-4- Piperidyl) -adipate, bis (2,2,6,6-tetramethyl-4-piperidyl) -terephthalate, 1,2-bis (2,2,6,6-tetramethyl-4-pi Lysyloxy) -ethane, α, α′-bis (2,2,6,6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6,6-tetramethyl-4-piperidyl) Tolylene-2,4-dicarbamate, bis (2,2,6,6-tetramethyl-4-piperidyl) -hexamethylene-1,6-dicarbamate, tris (2,2,6,6-tetramethyl- 4-piperidyl) -benzene-1,3,5-tricarboxylate, tris (2,2,6,6-tetramethyl-4-piperidyl) -benzene-1,3,4-tricarboxylate, 1,2 , 3,4-Butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9- (2,4,8, 10-tetraoxaspiro [5,5] un Decane) -diethanol condensate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, 1,2,3,4-butanetetra It is a condensate of carboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and tridecyl alcohol.
These hindered amine light stabilizers may be used alone or in combination of two or more.

  As the weather resistance (light) stabilizer, the benzotriazole ultraviolet absorber, oxalic anilide ultraviolet absorber, and hindered amine light stabilizer are preferably used in combination.

Examples of the polyalkylene glycol plasticizer include polycondensates having alkylene glycol as a monomer.
For example, polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol block polymer and the like.
The polyaddition mole number of polyalkylene glycol is preferably 5 to 1000.
The second group of polyoxyalkylene glycols includes ether compounds of the first group and aliphatic alcohols. Specifically, polyethylene glycol oleyl ether (ethylene oxide polymerization mole number 5 to 50), polyethylene glycol cetyl ether (ethylene oxide polymerization mole number 5 to 20), polyethylene glycol stearyl ether (ethylene oxide polymerization mole number 5 to 30), Polyethylene glycol lauryl ether (ethylene oxide polymerization mol number 5-30), polyethylene glycol tridecyl ether (ethylene oxide polymerization mol number 5-30), polyethylene glycol nonylphenyl ether (ethylene oxide polymerization mol number 2-100), polyethylene glycol oxy Tilphenyl ether (ethylene oxide polymerization mole number 4-50) etc. are mentioned.

Examples of the ester release agent include esters of alcohol and fatty acid, esters of alcohol and dicarboxylic acid, fatty acid amides, metal soaps, and olefin compounds having an average polymerization degree of 10 to 500.
Examples of the alcohol include monohydric alcohols and polyhydric alcohols.
Examples of monohydric alcohols include octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, bentadecyl alcohol, cetyl alcohol, hebutadecyl alcohol, stearyl alcohol, oleyl Alcohol, nonadecyl alcohol, eicosyl alcohol, pehenyl alcohol, ceryl alcohol, melyl alcohol, 2-hexyl decanol, 2-octyldodecanol, 2-decyl tetradecanol, unilin alcohol are mentioned.

  The polyhydric alcohol is a polyhydric alcohol containing 2 to 6 carbon atoms, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol dipropylene glycol, butanediol, pentanediol, hexanediol, glycerin, Examples include diglycerin, triglycerin, threitol, erythritol, pentaerythritol, arabitol, ribitol, xylitol, sorbite, sorbitan, sorbitol, and mannitol.

As fatty acids, capric acid, lauric acid, myristic acid, palmitic acid stearic acid, 12-hydroxystearic acid, alginate, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid, celloplastic acid, undecylenic acid, oleic acid , Elaidic acid, celetic acid, erucic acid, brassic acid, sorbic acid linoleic acid, linolenic acid, arachidonic acid, propiolic acid, stearolic acid and naturally occurring fatty acids containing these components or mixtures thereof. It is done.
These fatty acids may be substituted with a hydroxy group.

As the ester of alcohol and fatty acid, among fatty acid compounds, preferably a fatty acid selected from palmitic acid, stearic acid, behenic acid, and montanic acid, and a polyhydric alcohol selected from glycerin, pentaerythritol, sorbitan, and sorbitol And fatty acid esters derived from.
The hydroxyl group of the fatty acid ester compound may or may not exist. The fatty acid ester compound may be a monoester, a diester, or a triester. Further, the hydroxyl group may be blocked with boric acid or the like.
Specific examples of fatty acid ester compounds include glycerol monopalmitate, glycerol dipalmitate, glycerol tripalmitate, glycerol monostearate, glycerol distearate, glycerol tristearate, glycerol monobehenate, glycerol dibehenate, glycerol Tribehenate, glycerin monomontanate, glycerin dimontanate, glycerin trimontanate, pentaerythritol monopalmitate, pentaerythritol dipalmitate, pentaerythritol tripalmitate, pentaerythritol tetrapalmitate, pentaerythritol monostearate, Pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate, Pentaerythritol monobehenate, pentaerythritol dibehenate, pentaerythritol tribehenate, pentaerythritol tetrabehenate, pentaerythritol monomontanate, pentaerythritol dimontanate, pentaerythritol trimontanate, pentaerythritol tetramontanate, Sorbitan monopalmitate, sorbitan dipalmitate, sorbitan tripalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monobehenate, sorbitan dibehenate, sorbitan tribehenate, sorbitan monomontanate , Sorbitan dimontanate, sorbitan trimontanate, sorbitol monopalmitate, sorbitol dipalnate Tate, sorbitol tripalmitate, sorbitol monostearate, sorbitol distearate, sorbitol tristearate, sorbitol monobehenate, sorbitol dibehenate, sorbitol tribehenate sorbitol monomontanate, sorbitol dimontanate, sorbitol trimonta Nate.
Moreover, as an aliphatic ester compound whose hydroxyl group is blocked with boric acid or the like, a boric acid ester of glycerin monofatty acid ester may be mentioned.

The ester of alcohol and dicarboxylic acid is the following monoester or diester of alcohol and dicarboxylic acid.
Examples of alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, n-amyl alcohol, 2-pentanol, n-heptyl alcohol, n-octyl alcohol, and n-nonyl alcohol. And saturated / unsaturated alcohols such as lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and behenyl alcohol.
Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, brassic acid, maleic acid, fumaric acid, and glutaconic acid. .

As the fatty acid amide, an aliphatic amide compound composed of a C16 or higher aliphatic carboxylic acid, an amine and a diamine is used.
Examples of the aliphatic carboxylic acids constituting these aliphatic amides include palmitic acid, isopalmitic acid, stearic acid, isostearic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, cetrein An acid, erucic acid, etc. are mentioned.
Moreover, ammonia, ethylenediamine, etc. are mentioned as an amine and diamine which comprise aliphatic amide.
Specific examples of the aliphatic amide compound include stearyl amide, palmityl amide, oleyl amide, methylene bis stearamide, ethylene bis stearamide, ethylene bis oleyl amide, and the like.

  Examples of the metal soap include zinc stearate, calcium stearate, magnesium stearate and the like.

Examples of the olefin compound having an average degree of polymerization of 10 to 500 include compounds represented by the following formula (2).
(CH ₂ R ₁₀ R ₁₁ C) _n (2)
In the general formula (2), R ₁₀ and R ₁₁ are any one selected from the group consisting of hydrogen, an alkyl group, an aryl group, and an ether group, and may be the same or different. n is an average degree of polymerization of 10 to 500.
The alkyl group in the above formula is ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group, lauryl group, cetyl group, stearyl group and the like.
Examples of the aryl group include phenyl group, p-butylphenyl group, p-octylphenyl group, p-nonylphenyl group, benzyl group, p-butylbenzyl group, tolyl group, xylyl group and the like.
Moreover, as an ether group, an ethyl ether group, a propyl ether group, a butyl ether group etc. are mentioned, for example.
Examples of the monomer constituting the olefin compound include ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 2 -Olefin monomers represented by methyl-2-butene, 1-hexene, 2,3-dimethyl-2-butene, 1-heptene, 1-octene, 1-nonene, 1-decene, or allene, , 2-butadiene, 1,3-butadiene, 1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, cyclopentadiene, and the like.
The olefin compound having an average degree of polymerization of 10 to 500 may be a compound obtained by copolymerizing two or more of the olefin monomer and diolefin monomer.
If the olefin compound is a compound obtained by polymerizing a diolefin monomer, use an olefin compound with as few carbon-carbon unsaturated bonds as possible using a conventional hydrogenation method from the viewpoint of improving thermal stability. Is preferred.

  The method for adding the various additives and stabilizers described above is not particularly limited as long as it can be melt-kneaded using a single-screw or twin-screw extruder.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the Example mentioned later.

<Methods for measuring various physical properties in Examples and Comparative Examples>
[1. Melt flow rate value (hereinafter referred to as MFR value)]
According to ASTM D1238, MFR value was measured at a cylinder temperature of 190 ° C. and a load of 2.16 kg using a MELT INDEXER manufactured by Toyo Seiki Co., Ltd.

[2. Heat loss of polyacetal resin homopolymer (A)]
The polyacetal resin homopolymer was tableted with a tablet molding machine, the tablet was cut into a size of 1 mm square or less, and 0.25 g was put into a cylindrical glass test tube 1 having an inner diameter of 2φ (length: 50 mm). .
The test tube 1 was further placed in a glass test tube 2 having an inner diameter of 30 mm, and air in the test tube 2 was removed under a reduced pressure condition of −700 mmHg for 10 minutes.
Thereafter, while maintaining the reduced pressure state, the test tube 2 was immersed in an oil bath set at 222 ° C. and heated for 50 minutes.
After 50 minutes, the glass tube 2 was taken out and air-cooled to room temperature while maintaining the reduced pressure state.
After air cooling, the test tube 1 in the test tube 2 was taken out, the weight of the test tube 1 was measured, and the weight reduction amount was obtained from the weight before and after heating.

[3. amount of water〕
Before melt-kneading, the polyacetal resin homopolymer (A), the acrylamide polymer (B), the hydrazide compound (C), and the hindered phenol antioxidant were each taken out and 1 g was precisely weighed.
This sample was put into a Karl Fischer moisture meter (CA-21 type) manufactured by Mitsubishi Chemical Corporation, and the moisture content was quantified.
The reagent used was Aquamicron AX / CXU.

[4. Average particle diameter of acrylamide polymer (B)]
Acrylamide polymer 0.03g was disperse | distributed in ethanol (the Wako Pure Chemical Industries Ltd. make, reagent special grade), and the average particle diameter was measured using the following apparatus.
Particle size measuring device: SALD-2000 manufactured by Shimadzu Corporation

[5. Reduced viscosity of acrylamide (B)]
To 50 mL of formic acid (special grade reagent), 0.50 g of acrylamide polymer (B) was added and stirred for 2 hours.
Thereafter, the drop speed (t1) was measured using an Ostwald viscometer, and the reduced viscosity was measured from the time difference of the drop speed (t0) of the blank value (no acrylamide polymer).
The temperature of the thermostatic chamber was 35 ° C. ± 1 ° C. As the viscosity solvent, formic acid was used.

[6. Melting point measurement of hydrazide compound)
3 mg of the hydrazide compound was precisely weighed and sealed with an aluminum pon. Thereafter, the melting point was measured under the following conditions.
Apparatus: DSC-7 manufactured by PerkinElmer
Measurement conditions: The temperature was raised from 30 ° C. to 200 ° C. at a rate of 2.5 ° C./min, and the change in calorie (first scan) was measured. The temperature at the peak top of the maximum endothermic peak at this time was defined as the melting point.

[7. Extrusion productivity of polyacetal resin composition)
Using a TEX65φ vented twin-screw extruder (L / D = 32) manufactured by Nippon Steel Works, the extrusion productivity of the polyacetal resin composition was evaluated under the following conditions.
(A) Extrusion conditions Cylinder set temperature: 205 ° C
Screw rotation speed: 60rpm
Discharge rate: 80 kg / hr
Screen mesh: 3 layers of 100 mesh x 150 mesh x 100 mesh Vent pressure: -700mmHg reduced pressure Pressure in the extruder popper: 5kPa
(B) Criteria for Extrusion Productivity After the start of extrusion, the extrusion time when the resin pressure of the extruder die part reached a resin pressure of +10 kg / cm ² than before the start of extrusion was measured and evaluated.
A continuous extrusion time of 24 hours or longer was judged to be practically good.

[8. Molding productivity)
Using an injection molding machine “IS100GN” manufactured by Toshiba Machine Co., Ltd., 10,000 shots are continuously molded, and components other than polyacetal resin (formaldehyde-derived carbides and acrylamide polymer aggregates) present in the molded product after 10,000 shots , And a modified product due to burning) were measured according to the following criteria, and molding productivity was evaluated.
(A) Molding conditions Cylinder set temperature: 205 ° C
Mold temperature: 70 ℃
Molding cycle: Injection / cooling = 15 sec / 10 sec Shape of molded product: 60 mm × 40 mm × 1 mm flat plate (b) Molding productivity The size of carbides or aggregates present on the surface of the molded product is scored as follows: The molding productivity was determined based on the numerical value calculated by the number of points × number.
(For foreign material size score standard)
Carbides with a maximum carbide size of less than 0.1 mm are present: 0 points Carbides with a size of less than 0.1 mm to 0.3 mm are present: 1 point Carbides with a size of less than 0.3 mm to less than 0.5 mm Is present: 3 points Carbide having a size of more than 0.5 mm is present: 5 points If the value of the above score × number is 20 points or less, it was judged to be good.

[9. Mechanical properties)
An ISO test piece was molded under the following molding conditions using an injection molding machine “IS100GN” manufactured by Toshiba Machine Co., Ltd., and the tensile fracture strength, tensile fracture elongation, and tensile elastic modulus were measured.
(A) Molding conditions Cylinder set temperature: 210 ° C
Mold temperature: 90 ℃
Molding cycle: Injection / cooling = 60 seconds / 20 seconds (b) Mechanical property measurement conditions Measured according to ISO527.
If the tensile strength at break ≧ 60 MPa, the tensile elongation at break ≧ 50%, and the tensile modulus ≧ 2500 MPa, it was judged to be practically good.

[10. (Thermal stability)
Using an injection molding machine “EC5P” manufactured by Toshiba Machine Co., Ltd., the sample was retained in the injection molding machine under the following conditions, and the time when silver streaks occurred was measured to evaluate the thermal stability.
(A) Molding conditions Cylinder set temperature: 230 ° C
Mold temperature: 80 ℃
Molding cycle: Injection / cooling = 30 seconds / 15 seconds Test piece: 127 mm × 12.7 mm × 3 mm
(B) Thermal stability measurement and evaluation method The polyacetal resin composition was plasticized and melted in an injection molding machine set to the above molding conditions, and the molten resin was retained in the injection molding machine.
Thereafter, the molten resin retained in the injection molding machine was injection-molded at regular intervals, the surface state of the obtained molded product was visually observed, and the thermal stability was evaluated with the residence time when silver streak occurred. .
If the residence time was 30 minutes or longer, it was judged that the thermal stability was excellent.

[11. Hydrothermal aging property)
[9. Using the ISO test piece prepared in [Mechanical Properties], this test piece was immersed in a container set at 120 ° C., and the test piece was taken out at regular intervals to measure the physical properties.
The hot water aging property was evaluated by the number of days when the tensile yield strength retention after the hot water test reached 90% or less with respect to the tensile yield strength before the start of the hot water test. The tensile yield strength was measured according to ISO 527.
If it was 12 days or more, it was judged that it was excellent in hot-water aging property.

[12. (Creep characteristics)
A creep test was performed in accordance with the following conditions, and the creep rupture time (hrs) was evaluated.
(A) Molding conditions Injection molding machine: “IS100GN” manufactured by Toshiba Machine
Cylinder set temperature: 205 ° C
Mold temperature: 80 ℃
Test specimen size: 110 × 15 × 3 mm tensile specimen (b) Test conditions Creep tester: Toyo Seiki creep tester Test temperature and tensile stress: 80 ° C. × 22 MPa
When the creep rupture time was 700 hours or more, it was judged to be practically good.

[13. (Mold depositability)
The polyacetal resin composition was dried at 80 ° C. for 3 hours and then continuously molded under the following molding conditions.
After continuous molding, the mold was taken out, the state of dirt on the mold surface was visually observed, and mold depositability was evaluated according to the following criteria.
(A) Molding conditions Injection molding machine: Ti-30G manufactured by Toyo Seiki
Cylinder set temperature: 210 ° C
Mold setting temperature: 30 ℃
Molding cycle: Injection / cooling = 10/5 seconds Mold size: 30mm × 12mm × 2mm vertical mold
(A gas vent is installed at the end of the flow end)
Number of molding shots: 10000 shots (b) Criteria No contamination inside or outside the mold cavity and the degassing part: 0
There is a slight dirt on the mold vent: 1
Dirt in the range of about 1/5 of the mold cavity: 2
Dirt in the range of about 1/2 of the mold cavity: 3
Dirt on the entire inside and outside of the mold cavity: 4
There is dirt in the entire mold cavity, and it does not come off when wiped with a non-woven fabric: 5

<Raw material of polyacetal resin composition>
[Polyacetal resin homopolymer (A): (A-1) to (A-7)]
(A-1)
A polymerization reactor equipped with a stirring blade is filled with n-hexane, and formaldehyde gas (water content: 110 ppm), a polymerization catalyst (dimethyl distearyl ammonium acetate), and a molecular weight regulator (acetic anhydride) are continuously added. And polymerized.
The polymerization reaction temperature at this time was 58 ° C.
The crude polyacetal resin homopolymer obtained under these conditions was put into a reaction vessel filled with a one-to-one mixed solvent of hexane and acetic anhydride, and the unstable terminal of the crude polyacetal resin homopolymer was esterified at 150 ° C. for 2 hours. Processed.
At this time, the mass ratio (slurry concentration) of the one-to-one mixed solvent of hexane and acetic anhydride was 20 with respect to the one-to-one mixed solvent 100 of hexane and acetic anhydride.
After the end stabilization treatment of the polyacetal resin homopolymer is completed, take out a one-to-one mixed solvent of hexane and acetic anhydride and the polyacetal resin homopolymer from the reaction vessel, add fresh n-hexane solvent, and repeatedly wash the polyacetal resin homopolymer. The acetic anhydride was washed off.
The number of washings was repeated until the acetic anhydride concentration in the polyacetal resin homopolymer was 10 ppm or less.
Thereafter, the polyacetal resin homopolymer stabilized at −700 mmHg for 3 hours at 120 ° C. was dried under reduced pressure, the n-hexane solvent used for washing was removed, and a heating dryer set at 120 ° C. It was used and dried for 5 hours to remove water contained in the polyacetal resin homopolymer.
Then, it cooled to room temperature and measured the MFR value, the heating weight loss, and the moisture content according to the method of said [1], [2], and [3].
Table 1 below shows the MFR value and the weight loss by heating of the obtained polyacetal resin homopolymer.

(A-2 to A-7)
The terminal stabilization conditions of the crude polyacetal resin were changed to produce polyacetal resin homopolymers (A-2 to A-7) having different MFR values and heating weight loss amounts.

[Acrylamide polymer (B): (B-1) to (B-7)]
(B-1)
To a batch type 5 L reactor equipped with a stirrer, add 2400 g of acrylamide, 267 g of methylenebisacrylamide, and 0.54 g of zirconium tetraisopropoxide as a catalyst (1/10000 mol with respect to acrylamide) and stirring in an N ₂ stream The reaction was carried out at 125 ° C. for 4 hours.
After completion of the reaction, the solid was pulverized with a jet mill pulverizer and washed with acetone.
Thereafter, for the purpose of further removing the water content, it was dried under reduced pressure at 120 ° C. for 20 hours at a reduced pressure of −700 mmHg to adjust the water content contained in the acrylamide polymer.
Thereafter, the primary amide group content, reduced viscosity, and average particle size were measured and packed in a sealed bag. The measurement results are shown in Table 2 below.

(B-2 to B-5, B-7)
Crushing conditions and drying conditions of the acrylamide polymer were changed to produce acrylamide polymers having different water contents and average particle diameters. The measurement results are shown in Table 2 below.
The pulverization conditions were such that after completion of the polymerization reaction of the acrylamide polymer, pulverization was performed using a jet mill type pulverizer until a predetermined particle size was obtained, and the pulverization time was adjusted.
Moreover, the drying conditions were arbitrarily selected and adjusted in the range of a reduced pressure of −500 mmHg to −700 mmHg, a drying temperature of 60 to 70 ° C., and a drying time of 1 to 30 hours.

(B-6)
Methylene bisacrylamide was not used. Other conditions performed the same operation as said (B-1), and manufactured the non-crosslinked acrylamide polymer.
The measurement results are shown in Table 2 below.

[Hydrazide Compound (C): (C-1) to (C-7)]
(C-1)
A 1: 1 mixture of methanol and water was charged with 2.5 mol of hydrazine hydrate per 1 mol of dimethyl sebacate and allowed to react at 60 ° C. for 2 hours with stirring.
Thereafter, the methanol / water mixture was separated, and the resulting sebacic acid dihydrazide was dried.
The drying condition was a reduced pressure of −700 mmHg for 3 hours at a temperature of 120 ° C.
The melting point and water content of the obtained sebacic acid dihydrazide are shown in Table 3 below.

(C-2) to (C-5)
The vacuum drying conditions were changed as follows to obtain sebacic acid dihydrazide.
Other conditions were the same as in (C-1) above.
(C-2): 2 hours drying (C-3): 1.5 hours drying (C-4): 1 hour drying (C-5): 30 minutes drying (C-6): 1.5 hours drying ( C-7): Drying for 30 minutes The melting point and water content of the obtained sebacic acid dihydrazide are shown in Table 3 below.

(C-6) to (C-7)
Instead of dimethyl sebacate, dimethyl adipate was used. Other conditions performed the same operation as said (C-1), and obtained the adipic acid dihydrazide.
The melting point and water content of the obtained adipic acid dihydrazide are shown in Table 3 below.

[Hindered phenolic antioxidant (D): (D-1)]
(D-1)
Triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] was used.
The water content was 34 ppm.

[Other additives (E): (E-1) to (E-5)]
(E-1)
A terpolymer of polyamide 6/66/610 produced as follows was used.
The water content was 56 ppm.
0.45 kg of equimolar salt of adipic acid and hexamethylenediamine, 0.32 kg of equimolar salt of sebacic acid and hexamethylenediamine, 1.67 kg of ε-caprolactam, and 2.5 kg of pure water were added to a 5 L autoclave. Stir in and stir.
After sufficiently performing N ₂ substitution, the temperature was raised from room temperature to 220 ° C. over about 1 hour with stirring.
At this time, the internal pressure is kept constant at 18 kg / cm ² -G by the natural pressure of water vapor in the autoclave, and further heating is continued while removing water from the reaction system so as not to exceed this pressure. When the temperature reached 230 ° C., heating was stopped, the autoclave discharge valve was closed, and the mixture was cooled to room temperature over about 8 hours.
After cooling, the autoclave was opened, and about 2 kg of polymer was taken out and pulverized to form a powder.
The melting point was 150 ° C. and the relative viscosity was 2.0.
Then, it dried at 80 degreeC and the reduced pressure degree of -700 mmHg for 5 hours using the vacuum dryer, and adjusted the moisture content to 56 ppm.

(E-2)
2- [2-Hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl] benzotriazole was used as an ultraviolet absorber.
The amount of water was adjusted to 25 ppm.

(E-3)
As hindered amine light stabilizers, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl- A condensate with 3,9- (2,4,8,10-tetraoxaspiro [5,5] undecane) -diethanol was used.
The water content was adjusted to 35 ppm.

(E-4)
Polyethylene glycol (molecular weight: 6000) was used as a plasticizer.
The water content was adjusted to 87 ppm.

(E-5)
As a sliding agent, 1-propene (propylene): a liquid polyolefin oligomer (trade name: Lucant HC600) manufactured by Mitsui Chemicals, Inc. was used.
The kinematic viscosity (100 ° C.) was 600 mm ² / s.
The water content was adjusted to 53 ppm.

[Example 1]
The polyacetal resin homopolymer (A-2) was dried at 120 ° C. for 3 hours under nitrogen atmosphere and cooled to room temperature.
Thereafter, the polyacetal resin homopolymer (A-2) was put into a planetary motion type stirring mixer (SV mixer manufactured by Shinko Faudler), and the acrylamide polymer (B-1) and sebacin taken out from the sealed container. Acid dihydrazide (C-1) was also charged into a planetary motion type mixer.
The mass ratio at this time is 0.1 part by mass of the acrylamide polymer (B-1) and 0.05 part by mass of sebacic acid dihydrazide (C-1) with respect to 100 parts by mass of the polyacetal resin homopolymer (A-2). It was.
Further, 0.15 parts by mass of a hindered phenol antioxidant (D-1) was charged into a planetary motion type stirring mixer.
Thereafter, the upper lid of the stirring mixer was closed, nitrogen was flowed to adjust the pressure in the stirring mixer to a pressure of 5 kPa, and stirring and mixing were started.
The stirring and mixing conditions at this time were a temperature of 60 ° C., a stirring and mixing rotation speed of 10 rpm, and a stirring and mixing time of 2 hours.
After completion of the stirring and mixing, the valve installed at the bottom of the stirring and mixing machine was opened, and the mixture was put into the extruder hopper through a pipe.
The pressure in the extruder hopper at this time was also adjusted to a pressure of 5 kPa with nitrogen in the same manner as in the stirring mixer.
Thereafter, melt kneading was started with a 65φ twin-screw extruder (L / D = 32) (TEX65 manufactured by Nippon Steel).
The melt kneading conditions at this time were as follows: the cylinder set temperature was 205 ° C., the screw rotation speed was 60 rpm, the discharge rate was 80 kg / hr, three screen meshes were stacked 100 × 150 × 100 mesh, and the vent pressure reduction was −700 mmHg. .
After the start of melt kneading, the increase in the resin pressure in the extruder die was confirmed, the time when the resin pressure reached +10 kg / cm ² immediately after the start of extrusion was measured, and the extrusion productivity was evaluated.
Further, using the obtained polyacetal resin composition, molding productivity and mechanical properties, thermal stability, hot water aging properties, creep properties, and mold deposit properties were evaluated.
The material composition of the polyacetal resin composition is shown in Table 4 below, and the evaluation results are shown in Table 5 below.

[Examples 2 to 5], [Comparative Examples 1 and 2]
The kind of polyacetal resin homopolymer (A) was changed.
Other conditions were the same as in Example 1.
The material composition of the polyacetal resin composition is shown in Tables 4 and 6 below, and the evaluation results are shown in Tables 5 and 7 below.

[Examples 6 to 9]
The kind of acrylamide polymer (B) was changed.
The other conditions were the same as in Example 1 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 4 below, and the evaluation results are shown in Table 5 below.

[Comparative Examples 3 and 4]
The kind of acrylamide polymer (B) was changed.
The other conditions were the same as in Comparative Example 2 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 6 below, and the evaluation results are shown in Table 7 below.

[Examples 10 to 13]
The kind of hydrazide compound (C) was changed.
The other conditions were the same as in Example 1 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 4 below, and the evaluation results are shown in Table 5 below.

[Comparative Examples 5 and 6]
The kind of hydrazide compound (C) was changed.
The other conditions were the same as in Comparative Example 2 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 6 below, and the evaluation results are shown in Table 7 below.

[Examples 14 to 18]
The blending ratio of the acrylamide polymer (B) and the hydrazide compound (C) was changed.
The other conditions were the same as in Example 1 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 4 below, and the evaluation results are shown in Table 5 below.

[Comparative Example 7]
The blending ratio of the acrylamide polymer (B) and the hydrazide compound (C) was changed.
The other conditions were the same as in Comparative Example 2 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 6 below, and the evaluation results are shown in Table 7 below.

[Comparative Example 8]
The hydrazide compound (C) was not added.
The other conditions were the same as in Comparative Example 2 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 6 below, and the evaluation results are shown in Table 7 below.

[Comparative Example 9]
Acrylamide (B) was not added.
The other conditions were the same as in Comparative Example 2 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 6 below, and the evaluation results are shown in Table 7 below.

Example 19
In addition to the composition of the polyacetal resin composition described in Example 1, 0.02 parts by mass of polyamide 6/66/610 ternary copolymer (E-1) was further added.
The other conditions were the same as in Example 1 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 4 below, and the evaluation results are shown in Table 5 below.

Example 20
In addition to the polyacetal resin composition described in Example 1 above, 2- [2-hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl] benzotriazole (E-2) was further changed to 0. .25 parts by weight, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9 -(2,4,8,10-tetraoxaspiro [5,5] undecane) -diethanol condensate (E-3) 0.15 parts by mass, polyethylene glycol (E-4) 1.0 parts by mass Part was added.
The other conditions were the same as in Example 1 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 4 below, and the evaluation results are shown in Table 5 below.

Example 21
In addition to the composition of the polyacetal resin composition described in Example 1, 0.2 parts by mass of 1-propane (propylene) 600 (E-5) and 1.0 parts by mass of polyethylene glycol (E-4) Added.
The other conditions were the same as in Example 1 and the operation was performed.
The material composition of the polyacetal resin composition is shown in Table 4 below, and the evaluation results are shown in Table 5 below.

  As is clear from the compositions of the resin compositions in Tables 4 and 6 and the evaluation results in Tables 5 and 7, according to Examples 1 to 21, the polyacetal resin Pyrolysis and modification of various additives can be effectively suppressed, and molded articles produced using these polyacetal resin compositions have practically good mechanical properties, thermal stability, aging properties, and mold deposit properties. I found it.

  The polyacetal resin composition obtained by the production method of the present invention and a molded body using the same have industrial applicability as electrical, electronic equipment parts, automobile mechanism parts, industrial mechanism parts, and the like.

Claims (5)

Polyacetal resin homopolymer (A),
An acrylamide polymer (B) having a structure represented by the following general formula (I) and / or (II):
Hydrazide compound (C),
And hindered phenol antioxidants (D)
A process for producing a polyacetal resin composition comprising:
Obtaining a polyacetal resin homopolymer (A) having a weight loss by heating of 0.1 to 1.0 mass% when heated at 222 ° C. for 50 minutes under a pressure condition of −500 mmHg or less;
Adjusting the water content of the acrylamide polymer (B) to 1500 ppm or less;
Adjusting the water content of the hydrazide compound (C) to 1500 ppm or less;
Melting and kneading the polyacetal resin homopolymer (A), the acrylamide polymer (B), the hydrazide compound (C), and the hindered phenol-based antioxidant (D);
The manufacturing method of the polyacetal resin composition which has these.

  The method for producing a polyacetal resin composition according to claim 1, wherein the acrylamide polymer (B) has an average particle size of 0.1 to 10 µm.   The total amount (B + C) of the addition amount of the acrylamide polymer (B) and the hydrazide compound (C) is 0.001 to 1.0 part by mass with respect to 100 parts by mass of the polyacetal resin homopolymer (A). Item 3. A method for producing a polyacetal resin composition according to Item 1 or 2.   The polyacetal resin composition according to any one of claims 1 to 3, wherein a blending ratio (B) / (C) of the acrylamide polymer (B) and the hydrazide compound (C) is 1 to 25. Manufacturing method.   The polyacetal resin composition obtained by the manufacturing method of the polyacetal resin composition as described in any one of Claims 1 thru | or 4.