JP2019218443A - Polyacetal resin composition - Google Patents

Abstract

To provide a polyacetal resin composition which emits less formaldehyde even in a molded article molded under severe conditions such as high temperature and a long time residence.SOLUTION: There is provided a polyacetal resin composition which comprises at least (A) 100 pts.mass of a polyacetal resin, (B) 0.001 to 10 pts.mass of an aliphatic carboxylic acid having 4 or more carbon atoms and two or more carboxyl groups in the molecule and (C) 0.01 to 10 pts.mass of an amine compound having 3 or more carbon atoms represented by the following formula (1). R1, R2 and R3 represent a hydrogen atom, a hydroxyalkyl group having 1 to 4 carbon atoms or a hydrocarbon group having 1 to 9 carbon atoms and at least one of R1, R2 and R3 is a hydroxyalkyl group having 1 to 4 carbon atoms.SELECTED DRAWING: None

Description

  The present invention relates to a polyacetal resin composition in which the amount of formaldehyde generated is remarkably suppressed, and which is excellent in moldability.

Polyacetal resin is excellent in mechanical properties, fatigue resistance, friction and abrasion resistance, chemical resistance and moldability, so it is used in automobile parts, electric and electronic equipment parts, other precision machine parts, building materials and piping materials, It is widely used in the fields of living / cosmetic parts and medical parts.
However, with the expansion and diversification of applications, the demand for the quality has been increasing. There is an extremely high demand for protecting the environment around the use of end products, especially as automotive parts, from formaldehyde contamination.

  The automotive industry has established various standards that govern the generation of formaldehyde from polyacetal resins. For example, VDA 275 (German Automobile Manufacturers Association Standard) is a typical evaluation and is commonly used. However, as the versatility of polyacetal resin increases, it is necessary to satisfy more severe various conditions. I have.

  A technique for containing a primary amine or a secondary amine in a polyacetal homopolymer resin to reduce the generation of formaldehyde, and a technique for containing a hydrazide compound as a polyacetal resin composition that can withstand severe conditions have been proposed. (Patent Documents 1 and 2). Further, a technique has been proposed in which an ethylene-methacrylic acid copolymer is contained in a polyacetal copolymer resin (Patent Document 3).

JP 2002-541288 A JP 2013-010870 A JP-A-2015-101599

Polyacetal resins that satisfy a wide range of goals, including newly established standards in the automotive industry, are required, but none of the above technologies have been satisfactory.
An object of the present invention is to provide a polyacetal resin composition which does not generate formaldehyde even in a molded article molded under severe molding conditions such as high temperature and long residence time.

ここで、Ｒ１，Ｒ２，Ｒ３は、水素原子、炭素数１〜４のヒドロキシアルキル基または炭素数１〜９の炭化水素基を表し、Ｒ１，Ｒ２，Ｒ３の少なくとも１つが炭素数１〜４のヒドロキシアルキル基である。
２．さらに、（Ｄ）脂肪酸カルシウム塩０．０１〜０．３質量部を含有する前記１記載のポリアセタール樹脂組成物。
３．前記（Ｂ）脂肪族カルボン酸が、アジピン酸およびドデカン二酸から選択される少なくとも１種である前記１又は２記載のポリアセタール樹脂組成物。
４．前記（Ｃ）が、トリス（ヒドロキシメチル）アミノメタン、２−アミノ−２−エチル−プロパンジオール、および、２−アミノ−２−メチル−プロパノールから選択される少なくとも１種である前記１〜３記載のポリアセタール樹脂組成物。 The present invention has been achieved by the following.
1. at least,
(A) 100 parts by mass of a polyacetal resin (B) 0.001 to 10 parts by mass of an aliphatic carboxylic acid having 4 or more carbon atoms and having two or more carboxyl groups in a molecule;
(C) 0.01 to 10 parts by mass of an amine compound having 3 or more carbon atoms represented by the following formula (1):
And a polyacetal resin composition containing:

Here, R1, R2, and R3 represent a hydrogen atom, a hydroxyalkyl group having 1 to 4 carbon atoms or a hydrocarbon group having 1 to 9 carbon atoms, and at least one of R1, R2, and R3 has 1 to 4 carbon atoms. It is a hydroxyalkyl group.
2. 2. The polyacetal resin composition according to the above item 1, further comprising (D) 0.01 to 0.3 parts by mass of a fatty acid calcium salt.
3. 3. The polyacetal resin composition according to the above 1 or 2, wherein the aliphatic carboxylic acid (B) is at least one selected from adipic acid and dodecanedioic acid.
4. The above (1) to (3), wherein (C) is at least one selected from tris (hydroxymethyl) aminomethane, 2-amino-2-ethyl-propanediol, and 2-amino-2-methyl-propanol. Polyacetal resin composition.

  ADVANTAGE OF THE INVENTION According to this invention, the polyacetal resin composition with little generation | occurrence | production of formaldehyde can be provided also in the molded article shape | molded on severe shaping | molding conditions, such as high temperature and prolonged residence time.

  Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the following embodiments. The present invention also includes a polyacetal resin molded product composed of the polyacetal resin composition.

ここで、Ｒ１，Ｒ２，Ｒ３は、水素原子、炭素数１〜４のヒドロキシアルキル基または炭素数１〜９の炭化水素基を表し、Ｒ１，Ｒ２，Ｒ３の少なくとも１つが炭素数１〜４のヒドロキシアルキル基である。 <Polyacetal resin composition>
The polyacetal resin composition of the present invention,
(A) 100 parts by mass of a polyacetal resin (B) 0.001 to 10 parts by mass of an aliphatic carboxylic acid having 4 or more carbon atoms and having two or more carboxyl groups in a molecule;
(C) 0.01 to 10 parts by mass of an amine compound having 3 or more carbon atoms represented by the following formula (1):
And is characterized by containing.

Here, R1, R2, and R3 represent a hydrogen atom, a hydroxyalkyl group having 1 to 4 carbon atoms or a hydrocarbon group having 1 to 9 carbon atoms, and at least one of R1, R2, and R3 has 1 to 4 carbon atoms. It is a hydroxyalkyl group.

<(A) polyacetal resin>
The polyacetal resin of the present invention is a polymer compound having an oxymethylene group (—OCH ₂ —) as a main constituent unit, and a polyacetal homopolymer (for example, trade name “Delrin” manufactured by DuPont, USA; Asahi Kasei Corporation) Polyacetal copolymers containing other comonomer units in addition to the oxymethylene group (for example, Polyplastics Co., Ltd., trade name “Duracon”).

In the copolymer, the comonomer unit includes an oxyalkylene unit having about 2 to 6 carbon atoms (preferably about 2 to 4 carbon atoms) (for example, an oxyethylene group (—OCH ₂ CH ₂ —), an oxypropylene group, an oxytetramethylene group). Groups).

  The content of the comonomer unit is, for example, 0.01 to 20 mol%, preferably 0.03 to 10 mol% (for example, 0.05 to 5 mol%), more preferably 0.1 to 20 mol%, based on the entire polyacetal resin. It can be selected from a range of about 1 to 5 mol%.

  The polyacetal copolymer may be a two-component copolymer, a three-component terpolymer, or the like. The polyacetal copolymer may be a random copolymer, a block copolymer, a graft copolymer, or the like.

  Further, the polyacetal resin may have a branched structure as well as a linear structure, and may have a crosslinked structure. Furthermore, the terminal of the polyacetal resin may be stabilized by, for example, esterification with a carboxylic acid such as acetic acid or propionic acid or an anhydride thereof. The degree of polymerization, the degree of branching, and the degree of crosslinking of the polyacetal are not particularly limited as long as they can be melt-molded.

  The polyacetal resin, for example, homopolymerization of formaldehyde, trioxane, ethylene oxide, propylene oxide, 1,3-dioxolan, diethylene glycol formal, by copolymerizing a cyclic ether or cyclic formal such as 1,4-butanediol formal Can be manufactured.

<(B) Aliphatic carboxylic acid having 4 or more carbon atoms and having two or more carboxyl groups in the molecule>
An aliphatic carboxylic acid of the present invention having 4 or more carbon atoms and having two or more carboxyl groups in a molecule (hereinafter, may be abbreviated as a carboxylic acid of the present invention) includes an aliphatic dicarboxylic acid and an aliphatic tricarboxylic acid. Acids and aliphatic tetracarboxylic acids. The aliphatic carboxylic acid may be a monoester of an aliphatic tricarboxylic acid, a monoester of an aliphatic tetracarboxylic acid, or a diester of an aliphatic tetracarboxylic acid. Further, the aliphatic carboxylic acid may be a saturated carboxylic acid or an unsaturated carboxylic acid.

  Specific examples of the aliphatic saturated dicarboxylic acid having 4 or more carbon atoms include butanedioic acid (succinic acid, aliphatic saturated dicarboxylic acid having 4 carbon atoms) and pentanedioic acid (glutaric acid, 5 carbon atoms). Aliphatic saturated dicarboxylic acid), hexane diacid (adipic acid, aliphatic saturated dicarboxylic acid having 6 carbon atoms), heptane diacid (pimelic acid, aliphatic saturated dicarboxylic acid having 7 carbon atoms), octane diacid (Suberic acid, aliphatic saturated dicarboxylic acid having 8 carbon atoms), nonanedioic acid (azelaic acid, aliphatic saturated dicarboxylic acid having 9 carbon atoms), decane diacid (sebacic acid, 10 carbon atoms) Examples thereof include aliphatic saturated dicarboxylic acids), undecandioic acids (aliphatic saturated dicarboxylic acids having 11 carbon atoms), and dodecandioic acids (aliphatic saturated dicarboxylic acids having 12 carbon atoms).

  Specific examples of the aliphatic unsaturated dicarboxylic acid having 4 or more carbon atoms include butenedioic acid (fumaric acid, aliphatic unsaturated dicarboxylic acid having 4 carbon atoms) and pentenedioic acid (glutaconic acid, carbon number Is 5), hexenedioic acid (dihydromuconic acid, aliphatic unsaturated dicarboxylic acid having 6 carbon atoms), octenedioic acid (aliphatic unsaturated dicarboxylic acid having 8 carbon atoms) , Decenedioic acid (aliphatic unsaturated dicarboxylic acid having 10 carbon atoms), undecenedioic acid (aliphatic unsaturated dicarboxylic acid having 11 carbon atoms), dodecenedioic acid (aliphatic unsaturated dicarboxylic acid having 12 carbon atoms) Saturated dicarboxylic acid) and the like.

  Specific examples of the aliphatic tricarboxylic acid having 4 or more carbon atoms include 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid). Specific examples of the aliphatic tetracarboxylic acid having 4 or more carbon atoms include ethylene tetracarboxylic acid and the like.

  The aliphatic carboxylic acid of the present invention having 4 or more carbon atoms and having two or more carboxyl groups in the molecule is 0.001 to 10 parts by mass, preferably 0.005 to 10 parts by mass, based on 100 parts by mass of the polyacetal resin. One part by mass, particularly 0.01 to 0.5 part by mass, is preferred.

ここで、Ｒ１，Ｒ２，Ｒ３は、水素原子、炭素数１〜４のヒドロキシアルキル基または炭素数１〜９の炭化水素基を表し、Ｒ１，Ｒ２，Ｒ３の少なくとも１つが炭素数１〜４のヒドロキシアルキル基である。 <(C) Amine compound represented by the following formula (1)>
The amine compound having 3 or more carbon atoms of the present invention (hereinafter, also referred to as the amine compound (C) of the present invention) is a compound represented by the following formula (1).

Here, R1, R2, and R3 represent a hydrogen atom, a hydroxyalkyl group having 1 to 4 carbon atoms or a hydrocarbon group having 1 to 9 carbon atoms, and at least one of R1, R2, and R3 has 1 to 4 carbon atoms. It is a hydroxyalkyl group.

  Specific examples include, but are not limited to, tris (hydroxymethyl) aminomethane, 2-amino-2-ethyl-propanediol, and 2-amino-2-methyl-propanol, especially tris ( (Hydroxymethyl) aminomethane is preferred.

  The amine compound (C) of the present invention is contained in an amount of 0.01 to 10 parts by mass, preferably 0.02 to 5 parts by mass, and most preferably 0.05 to 2 parts by mass based on 100 parts by mass of the polyacetal resin.

<(D) Fatty acid calcium salt>
The polyacetal resin composition of the present invention may contain (D) a fatty acid calcium salt as an alkali component.

  The raw fatty acid of the fatty acid calcium salt may be a saturated fatty acid, an unsaturated fatty acid, or a fatty acid substituted with a hydroxyl group (hydroxycarboxylic acid). Further, the raw fatty acid may be a dicarboxylic acid, an oxocarboxylic acid, or a carboxylic acid derivative.

  As saturated fatty acids, ethanoic acid (acetic acid, carbon number: 2), propanoic acid (propionic acid, carbon number: 3), butanoic acid (butyric acid, carbon number: 4), pentanoic acid (valeric acid, carbon number: 5), Hexanoic acid (caproic acid, carbon number: 6), heptanoic acid (enanthic acid, carbon number: 7), octanoic acid (caprylic acid, carbon number: 8), nonanoic acid (pelargonic acid, carbon number: 9), decanoic acid (Capric acid, carbon number: 10), dodecanoic acid (lauric acid, carbon number: 12), tetradecanoic acid (myristic acid, carbon number: 14), hexadecanoic acid (palmitic acid, carbon number: 16), heptadecanoic acid (margarine) Acid, carbon number: 17), octadecanoic acid (stearic acid, carbon number: 18), eicosanoic acid (arachidic acid, carbon number: 20), docosanoic acid (behenic acid, carbon number: 22), octakoic acid (monta) Acid, carbon number: 28), and the like.

  As unsaturated fatty acids, sorbic acid (carbon number: 6), oleic acid (carbon number: 18), linoleic acid (carbon number: 18), linolenic acid (carbon number: 18), arachidonic acid (carbon number: 20), Eicosapentaenoic acid (carbon number: 20), docosahexaenoic acid (carbon number: 22) and the like.

  As aliphatic dicarboxylic acids, ethanedioic acid (oxalic acid, carbon number: 2), propanedioic acid (malonic acid, carbon number: 3), butanedioic acid (succinic acid, carbon number: 4), pentanedioic acid (glutaric acid) Acid, carbon number: 5), hexane diacid (adipic acid, carbon number: 6), heptane diacid (pimelic acid, carbon number: 7), octane diacid (suberic acid, carbon number: 8), nonanedioic acid (Azelaic acid, carbon number: 9), decandioic acid (sebacic acid, carbon number: 10), undecandioic acid (carbon number: 11), dodecanedioic acid (carbon number: 12) and the like.

  2-oxopropanoic acid (pyruvic acid, carbon number: 3) as an aliphatic oxocarboxylic acid, malic acid (carbon number: 4), citric acid (carbon number: 6), ricinoleic acid (carbon number) as a hydroxycarboxylic acid : 18), 12-hydroxystearic acid (carbon number: 18) and the like, and aliphatic tricarboxylic acid derivatives such as aconitic acid (carbon number: 6) and the like.

  In the present invention, two or more kinds of fatty acid calcium salts may be added at the same time, and there is no limitation. For example, calcium stearate and calcium palmitate may be added simultaneously, or a metal salt composed of a fatty acid having a different carbon number, for example, calcium (palmitate-stearate) may be mixed.

  In the present invention, the amount of the component (D) is 0.005 to 0.3 parts by mass, preferably 0.01 to 0.2 parts by mass, per 100 parts by mass of the polyacetal resin (A).

<Molar ratio of component (D) to component (B)>
When (D) fatty acid calcium salt is used in the present invention, (D) molar content of (D) fatty acid calcium salt / (B) aliphatic carboxylic acid is a molar ratio of (D) fatty acid calcium salt to (B) aliphatic carboxylic acid. Is preferably 0.1 or more and 5 or less, more preferably 0.3 or more and 4 or less.

  By setting the molar ratio in this range, sufficient heat stability can be obtained while suppressing the generation of formaldehyde from a molded article of the resin composition.

<Other additives>
The polyacetal resin composition of the present invention may further contain an antioxidant.

  As the antioxidant, known antioxidants can be used, and examples thereof include phenol-based (such as hindered phenols), amine-based, phosphorus-based, sulfur-based, hydroquinone-based, and quinoline-based antioxidants. Can be These antioxidants can be used alone or in combination of two or more.

  These antioxidants can be used alone or in combination of two or more. The content of the antioxidant is, for example, in the range of about 0.01 to 5 parts by weight, preferably about 0.05 to 2.5 parts by weight, particularly about 0.1 to 1 part by weight based on 100 parts by weight of the polyacetal resin. You can choose from.

The polyacetal resin composition of the present invention may further contain the following known stabilizers.
Stabilizers include, in particular, processing stabilizers and weather (light) stabilizers. As the processing stabilizer, at least one selected from known polyalkylene glycols, fatty acid esters, fatty acid amides and fatty acid metal salts can be used. The processing stabilizers may be used alone or in combination of two or more.

  The proportion of the processing stabilizer is about 0.01 to 10 parts by weight, preferably about 0.03 to 5 parts by weight (for example, 0.05 to 3 parts by weight), particularly about 0.05, based on 100 parts by weight of the polyacetal resin. About 2 parts by mass.

  Examples of the weather (light) stabilizer include (a) a benzotriazole compound, (b) a benzophenone compound, (c) an aromatic benzoate compound, (d) a cyanoacrylate compound, (e) an oxalic anilide compound, (F) Hindered amine compounds can be exemplified.

The weather (light) stabilizer may be used alone, but is preferably used alone or in combination of two or more. (A) benzotriazole-based compound, (b) benzophenone-based compound, (c) fragrance It is preferable to use a weather (light) stabilizer of an aromatic benzoate compound, (d) a cyanoacrylate compound, and / or (e) an oxalic anilide compound together with (f) a hindered amine compound.
The amount of the weather (light) stabilizer added is, for example, 0.01 to 5 parts by mass (for example, 0.01 to 3 parts by mass), preferably 0.01 to 2 parts by mass, per 100 parts by mass of the polyacetal resin. More preferably, it is about 0.1 to 2 parts by mass (for example, 0.1 to 1.5 parts by mass).

  It is possible to further mix a colorant with the polyacetal resin composition of the present invention. Various dyes or pigments can be used as the colorant. The dye is preferably a solvent dye, and examples thereof include an azo dye, an anthraquinone dye, a phthalocyanine dye, and a naphthoquinone dye. As the pigment, any of an inorganic pigment and an organic pigment can be used, and the pigment may be used alone, or a plurality of colorants may be used in combination.

  The content of the coloring agent is, for example, 0 to 5 parts by mass (for example, 0.01 to 5 parts by mass), preferably 0.1 to 4 parts by mass, and more preferably 0.1 to 4 parts by mass with respect to 100 parts by mass of the polyacetal resin. It is about 3 to 3 parts by mass.

  To the polyacetal resin composition of the present invention, if necessary, a release agent, a nucleating agent, an antistatic agent, a flame retardant, a surfactant, various polymers, a filler, and the like are added alone or in combination of two or more. May be.

<Production method of polyacetal resin composition>
The polyacetal resin composition of the present invention may be a powdery or granular mixture or a melt mixture, and the polyacetal resin, the carboxylic acid of the present invention and the amine compound of the present invention, and if necessary, other additives are used in a conventional manner. It can be prepared by mixing. For example, after mixing each component, kneading and extruding with a single-screw or twin-screw extruder to prepare pellets, a method of molding, once preparing pellets (master batch) having a different composition, and weighing the pellets in a predetermined amount A method of mixing (diluting) and subjecting to molding to obtain a molded product of a predetermined composition, a method of applying a suppressant to polyacetal resin pellets by spraying or the like, and then molding to obtain a molded product of a predetermined composition. Can be adopted.

  In addition, in the preparation of a composition used for a molded article, a powder of a polyacetal resin as a substrate (for example, a powder of a part or all of a polyacetal resin) and other components (aliphatic carboxylic acid, amine) Compound, fatty acid calcium salt, master batch of aliphatic carboxylic acid and amine compound, etc.) are mixed and melt-kneaded, which is advantageous for improving the dispersion of additives.

  Molded articles obtained from the composition of the present invention are most suitable for use in the automotive field, but are also used in mechanical and mechanical parts (active parts and passive parts, etc.) in the electric and electronic fields, building materials and piping fields, and daily necessities (life). -It is suitably used as parts and members in the cosmetics field and the medical field (medical and therapeutic fields).

  More specifically, as mechanical components in the automotive field, inner handles, fuel trunk openers, seat belt buckles, assist wraps, various switches, knobs, levers, interior parts such as clips, electric parts such as meters and connectors, Examples include in-vehicle electrical and electronic parts such as audio equipment and car navigation equipment, parts that come into contact with metals, such as carrier plates for window regulators, door lock actuator parts, mirror parts, wiper motor system parts, and fuel system parts. it can.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

  In Examples and Comparative Examples, the amount of formaldehyde generated from molded articles was evaluated as follows.

[Amount of formaldehyde generated from molded products]
Using the polyacetal resin compositions prepared in Examples and Comparative Examples, flat test pieces (100 mm × 40 mm × 2 mm) were molded under the following conditions. After leaving this plate-shaped test piece in an atmosphere of 23 ° C. and 50% RH, two plate-shaped test pieces were sealed in a 10 L vinyl fluoride sampling bag, degassed, and 4 L of nitrogen was added. After heating at 2 ° C. for 2 hours, 3 L of nitrogen in the sampling bag was withdrawn at 0.5 ml / min, and the generated formaldehyde was collected by a DNPH (2,4-dinitrophenylhydrazine) collection tube (Sep-Pak DNPH-Silica manufactured by Waters). ). Thereafter, the reaction product of DNPH and formaldehyde was extracted from the DNPH collection tube with acetonitrile as a solvent, and the amount of formaldehyde generated was determined by high performance liquid chromatography using a calibration curve method using a standard substance of the reaction product of DNPH and formaldehyde. The amount of formaldehyde generated (μg / g) per unit weight of the test piece was calculated.

* Molding machine: FANUC ROBOSHOT α-S100ia
* Molding conditions: Cylinder temperature (° C) nozzle -C1-C2-C3
220 220 220 220 220
Injection pressure 60 (MPa)
Injection speed 1.0 (m / min)
Residence time in molding machine 30 minutes
Mold temperature 80 (℃)

As examples and comparative examples, 100 parts by mass of a polyacetal resin were mixed with the materials and ratios shown in Tables 1 and 2 and then melt-mixed with a twin-screw extruder to prepare a pellet-shaped composition. To all the samples, 0.35 parts by mass of pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] was added as an antioxidant.
From the pellet composition, a test piece was molded by an injection molding machine, and the amount of formaldehyde generated from the test piece was measured. The evaluation is shown in Table 3. The units of the numerical values in Tables 1 and 2 are parts by mass.

Materials such as polyacetal resin used in Examples and Comparative Examples are as follows.
1. (A) Polyacetal resin (A-1): a polyacetal copolymer obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane (measurement index (at 190 ° C. under a load of 2160 g, measured) ): 9 g / 10 min)

2. (B) Aliphatic carboxylic acid (B-1): adipic acid (B-2): dodecane diacid

3. (C) Amine compound (C-1): tris (hydroxymethyl) aminomethane (THAM)
(C-2): 2-amino-2-methyl-propanol (AMP)
(C-3): Melamine (C-4): Benzoguanamine

4. (D) Fatty acid calcium salt (D-1): calcium stearate (D-2): calcium palmitate (D-3): 12-hydroxy calcium stearate

As is clear from Tables 3 and 4, the amount of formaldehyde generated from the molded article molded under the severe molding conditions of high temperature and long residence time was extremely small in the resin compositions of the examples compared to the comparative examples. And the quality of molded products can be improved.

Claims (4)

at least,
(A) 100 parts by mass of a polyacetal resin (B) 0.001 to 10 parts by mass of an aliphatic carboxylic acid having 4 or more carbon atoms and having two or more carboxyl groups in a molecule;
(C) 0.01 to 10 parts by mass of an amine compound having 3 or more carbon atoms represented by the following formula (1):
And a polyacetal resin composition containing:

R1, R2 and R3 represent a hydrogen atom, a C1 to C4 hydroxyalkyl group or a C1 to C9 hydrocarbon group, and at least one of R1, R2 and R3 is a C1 to C4 hydroxyalkyl group. It is.   The polyacetal resin composition according to claim 1, further comprising (D) 0.01 to 0.3 parts by mass of a fatty acid calcium salt. The polyacetal resin composition according to claim 1 or 2, wherein (B) the aliphatic carboxylic acid is at least one selected from adipic acid and dodecane diacid. The (C) is at least one selected from tris (hydroxymethyl) aminomethane, 2-amino-2-ethyl-propanediol, and 2-amino-2-methyl-propanol. The polyacetal resin composition according to the above.