JP5890754B2 - Polyacetal resin composition - Google Patents

Description

  The present invention relates to a polyacetal resin composition.

  The engineering plastics polyacetal resin has excellent mechanical properties, sliding properties, friction and wear properties, heat resistance, moldability and the like. For this reason, the polyacetal resin composition containing polyacetal resin is widely used for various machine parts, electrical parts, etc., such as a motor vehicle and OA apparatus.

  However, since polyacetal resin uses formaldehyde as its main raw material, it causes a slight thermal decomposition reaction due to a thermal history during processing and the like, and generates a very small amount of formaldehyde. Here, since formaldehyde may cause sick house syndrome and the like, a polyacetal resin composition in which generation of formaldehyde is sufficiently suppressed is demanded.

  As such a polyacetal resin composition, what is disclosed by the following patent document 1 is known. Patent Document 1 below discloses a polyacetal resin composition in which a polyacetal resin is blended with a hydrazide compound containing an aromatic group and a sterically hindered phenol. According to this polyacetal resin composition, it is generated from a product. It is disclosed that the amount of formaldehyde can be reduced.

JP 2005-162909 A

  By the way, a metal mold is used when the polyacetal resin composition is molded. At this time, the mold may be contaminated by adhesion of a compound generated by a thermal decomposition reaction during the molding process. When a molded product is repeatedly produced using this contaminated mold, the deposits attached to the mold are transferred as foreign matter to the molded product to be molded later, and in the worst case, it is necessary to discard the molded product. Become. Since disposal of the molded product leads to a decrease in the yield of the molded product, a polyacetal resin composition in which mold contamination is sufficiently suppressed is desirable.

  However, the polyacetal resin composition described in Patent Document 1 still has room for improvement in terms of suppressing mold contamination during molding. For this reason, the polyacetal resin composition which can fully suppress generation | occurrence | production of formaldehyde and can fully suppress the contamination of the metal mold | die at the time of a shaping | molding process was desired.

  An object of this invention is to provide the polyacetal resin composition which can fully suppress generation | occurrence | production of formaldehyde and can fully suppress the contamination of the metal mold | die at the time of a shaping | molding process.

  In order to suppress contamination of the mold during molding with the polyacetal resin composition described in Patent Document 1, the present inventors have examined improvements in the polyacetal resin composition. As a result, the present inventors changed the group bonded to the nitrogen atom in the amino group at the terminal of the hydrazide compound from a hydrogen atom to a group other than a hydrogen atom, thereby reacting the hydrazide compound with formaldehyde. It was thought that the product was difficult to bleed out from the polyacetal resin composition, or even if bleeded out, it was difficult to adhere to the mold, and contamination of the mold during molding could be sufficiently suppressed. Accordingly, the present inventors have conducted extensive research to realize a hydrazide compound in which the reaction product with formaldehyde is difficult to bleed out or hardly adheres to the mold even when bleeded out. The reaction product of hydrazide compound and formaldehyde is difficult to bleed out from the polyacetal resin composition by making the group bonded to the nitrogen atom in the amino group at the end of It has been found that it becomes difficult to adhere to the mold, and contamination of the mold during molding can be sufficiently suppressed. Furthermore, the present inventors have found that by adding a specific amount of hydrazide compound to the polyacetal resin, generation of formaldehyde can be sufficiently suppressed while sufficiently suppressing mold contamination during molding processing, The present invention has been completed.

（上記式中、ｍは正の整数を示し、ｎは０又は１を示す。Ｒ^１は（ｍ＋ｎ）価の基であって、炭素数１〜４０の脂肪族炭化水素基、炭素数３〜４０の脂環式炭化水素基、炭素数６〜１０の芳香族炭化水素基、炭素数２〜５の複素環基、又は、−ＣＺ^１Ｚ^２−ＣＺ^３Ｚ^４−を構成単位として含むポリマーの主鎖を示す。ｍ＝１、ｎ＝１である場合、Ｒ^１は単結合であってもよい。ｍ＝１、ｎ＝０である場合、Ｒ^１は水素原子であってもよい。Ｒ^２は、一価の基であって、炭素数１〜４０の脂肪族炭化水素基、炭素数３〜４０の脂環式炭化水素基、炭素数６〜１０の芳香族炭化水素基、炭素数２〜５の複素環基を示す。Ｚ^１〜Ｚ^４はそれぞれ独立に、単結合、水素原子又は炭素数１〜１０のアルキル基を示し、Ｚ^１〜Ｚ^４のうち少なくとも１つは単結合を示す。） That is, this invention is a polyacetal resin composition by which 0.05-5 mass parts of hydrazide compounds (B) represented by following General formula (1) are mix | blended with respect to 100 mass parts of polyacetal resin (A).

(In the above formula, m represents a positive integer, n represents 0 or 1. R ¹ is a (m + n) -valent group, an aliphatic hydrocarbon group having 1 to 40 carbon atoms, 3 to 3 carbon atoms, Polymer containing 40 alicyclic hydrocarbon group, 6 to 10 carbon aromatic hydrocarbon group, 2 to 5 carbon heterocyclic group, or -CZ ¹ Z ² -CZ ³ Z ⁴ -as a structural unit In the case where m = 1 and n = 1, R ¹ may be a single bond, and in the case where m = 1 and n = 0, R ¹ may be a hydrogen atom. R ² is a monovalent group, an aliphatic hydrocarbon group having 1 to 40 carbon atoms, an alicyclic hydrocarbon group having 3 to 40 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, carbon are each ^.Z 1 to Z ⁴ indicating the number 2-5 heterocyclic group independently represents a single bond, a hydrogen atom or an alkyl group having 1 to 10 carbon ^atoms, less of Z 1 to Z ⁴ Both one is a single bond.)

  According to the polyacetal resin composition of the present invention, generation of formaldehyde and contamination of the mold during molding can be sufficiently suppressed.

  Although the reason why the above effect is obtained is not clear, the present inventors presume as follows.

  When the polyacetal resin composition is heated and melted for molding, part of the polyacetal resin undergoes a thermal decomposition reaction to generate formaldehyde. The formaldehyde generated at this time is sufficiently consumed by reacting with the hydrazide compound in the polyacetal resin composition. At this time, the present inventors speculate that the generation of formaldehyde from the polyacetal resin composition may be sufficiently suppressed by blending the hydrazide compound in an appropriate amount.

In Patent Document 1 described above, the hydrazide compound is a compound represented by RCONHNH ₂ (R is an organic group), and the reaction between such a hydrazide compound and formaldehyde is an addition reaction followed by a dehydration reaction. as a result to produce a compound RCOCH ₂ NHN = CH ₂ having an imino group.

On the other hand, when the hydrazide compound has a group represented by -CONNHHR ² like the hydrazide compound (B) used in the present invention, the reaction between the hydrazide compound and formaldehyde is an addition reaction. As a compound RCONNHN (R ′) CH ₂ OH having a methylol group is produced.

  The present inventors speculate that the compound having the methylol group is less likely to bleed out from the polyacetal resin composition than the compound having the imino group, or is difficult to adhere to the mold even if bleeded out. Yes.

In the polyacetal resin composition, wherein in the general formula (1), it is preferred that R ² is a linear alkyl group having 1 to 18 carbon atoms.

  In this case, the reactivity between the hydrazide compound represented by the general formula (1) and formaldehyde becomes higher, and the generation of formaldehyde is more effectively suppressed.

In the polyacetal resin composition, in the general formula (1), it is preferred that R ² is a methyl group.

In this case, since the steric hindrance due to R ² is reduced, the reactivity between the hydrazide compound represented by the general formula (1) and formaldehyde is higher than when R ² is an alkyl group other than a methyl group. Thus, the generation of formaldehyde is further effectively suppressed.

  In the said polyacetal resin composition, it is preferable that it is n = 0 in the said General formula (1).

In this case, the group bonded to R ¹ is only m groups having a terminal R ² and does not include a group having a hydrogen atom at the terminal. That is, the group bonded to R ¹ is only one having higher reactivity with formaldehyde. For this reason, compared with the hydrazide compound which is n <= 0 in General formula (1), the reactivity of a hydrazide compound (B) and formaldehyde can be made higher, and generation | occurrence | production of formaldehyde can be suppressed more fully.

  In the said polyacetal resin composition, it is preferable that it is m = 2 and n = 0 in the said General formula (1).

In this case, since the group bonded to R ¹ is only a group having higher reactivity with formaldehyde, the hydrazide compound is compared with the hydrazide compound in which m = 1 and n = 0 in the general formula (1). The reactivity between (B) and formaldehyde can be further increased, and generation of formaldehyde can be more sufficiently suppressed. In addition, since the steric hindrance is reduced and it is easy to react with formaldehyde as compared with the hydrazide compound in which m is 3 or more and n = 0 in the general formula (1), generation of formaldehyde can be more sufficiently suppressed.

  In the said polyacetal resin composition, it is preferable that 0.01-3 mass parts of heat stabilizers (C) are mix | blended with respect to 100 mass parts of polyacetal resins.

  In this case, compared with the case where the amount of the heat stabilizer (C) is less than 0.01 parts by mass, the thermal decomposition of the polyacetal resin is more effectively suppressed, and the generation of formaldehyde is more effectively suppressed. . Moreover, compared with the case where the compounding quantity of a heat stabilizer (C) exceeds 3 mass parts, the mechanical characteristic of a polyacetal resin composition can be improved more.

  The heat stabilizer (C) is preferably at least one heat stabilizer selected from the group consisting of hindered phenol compounds and triazine compounds.

  In this case, the generation of formaldehyde is further effectively suppressed.

  In the said polyacetal resin composition, it is preferable that 0.01-3 mass parts of mold release agents (D) are mix | blended with respect to 100 mass of polyacetal resins.

  In this case, contamination of the mold during the molding process is more effectively suppressed as compared with the case where the amount of the release agent (D) is less than 0.01 parts by mass. Moreover, compared with the case where the compounding quantity of a mold release agent (D) exceeds 3 mass parts, the mechanical characteristic of a polyacetal resin composition can be improved more.

  The release agent (D) is preferably at least one release agent selected from the group consisting of polyethylene, silicone oil, fatty acid, fatty acid ester, and fatty acid metal salt.

  In this case, contamination of the mold during the molding process is further effectively suppressed.

  In the said polyacetal resin composition, it is preferable that 0.01-3 mass parts of anti-stabilizers (E) are mix | blended with respect to 100 mass of polyacetal resins.

  In this case, the deterioration of the polyacetal resin composition is sufficiently suppressed as compared with the case where the blending amount of the anti-glare stabilizer (E) is less than 0.01 parts by mass. Moreover, compared with the case where the compounding quantity of a weather-resistant stabilizer (E) exceeds 3 mass parts, the mechanical characteristic of a polyacetal resin composition can be improved more.

  The anti-smudge stabilizer (E) is preferably at least one anti-smudge stabilizer selected from the group consisting of a hindered amine light stabilizer and an ultraviolet absorber.

  In this case, deterioration of the polyacetal resin composition is effectively suppressed.

（上記式中、Ｒ^３は窒素原子との結合部が炭素原子である有機基、Ｘは酸素原子若しくは窒素原子を介してピペリジル基の４−位と結合する有機基または水素原子を示す。） In the polyacetal resin composition, the hindered amine light stabilizer is preferably a hindered amine light stabilizer represented by the following general formula (2).

(In the above formula, R ³ represents an organic group in which the bond to the nitrogen atom is a carbon atom, and X represents an organic group or hydrogen atom that is bonded to the 4-position of the piperidyl group via an oxygen atom or a nitrogen atom.)

  In this case, deterioration of the polyacetal resin composition is further effectively suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the polyacetal resin composition which can fully suppress generation | occurrence | production of formaldehyde and can fully suppress the contamination of the metal mold | die at the time of a shaping | molding process can be provided.

  Hereinafter, the present invention will be described in detail.

The present invention is a polyacetal resin composition in which 0.05 to 5 parts by mass of the hydrazide compound (B) represented by the following general formula (1) is blended with respect to 100 parts by mass of the polyacetal resin (A).

In the above formula, m represents a positive integer, and n represents 0 or 1. R ¹ is an (m + n) -valent group, an aliphatic hydrocarbon group having 1 to 40 carbon atoms, an alicyclic hydrocarbon group having 3 to 40 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, heterocyclic group having 2 to 5 carbon atoms, ^{or, -CZ 1 Z 2 -CZ 3 Z} 4 - shows the main chain of the polymer containing, as a structural unit. When m = 1 and n = 1, R ¹ may be a single bond. When m = 1 and n = 0, R ¹ may be a hydrogen atom. R ² is a monovalent group, an aliphatic hydrocarbon group having 1 to 40 carbon atoms, an alicyclic hydrocarbon group having 3 to 40 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, carbon The heterocyclic group of number 2-5 is shown. Z ^{1 to} Z ⁴ each independently represent a single bond, a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and at least one of Z ^{1 to} Z ⁴ represents a single bond.

  According to this polyacetal resin composition, generation of formaldehyde can be sufficiently suppressed, and contamination of the mold during molding can be sufficiently suppressed.

  Hereinafter, the polyacetal resin (A) and the hydrazide compound (B) used in the polyacetal resin composition of the present invention will be described in detail.

(A) Polyacetal resin The polyacetal resin is not particularly limited, and even if it is a homopolymer containing only a divalent oxymethylene group as a constituent unit, it has a divalent oxymethylene group and a carbon number of 2 to 6. A copolymer containing a divalent oxyalkylene group as a constituent unit may also be used.

  Examples of the oxyalkylene group having 2 to 6 carbon atoms include an oxyethylene group, an oxypropylene group, and an oxybutylene group.

  In the polyacetal resin, the ratio of the oxyalkylene group having 2 to 6 carbon atoms in the total number of moles of the oxymethylene group and the oxyalkylene group having 2 to 6 carbon atoms is not particularly limited. What is necessary is just mol%.

  In order to produce the polyacetal resin, trioxane is usually used as a main raw material. In order to introduce an oxyalkylene group having 2 to 6 carbon atoms into the polyacetal resin, for example, cyclic formal or cyclic ether can be used. Specific examples of cyclic formal include 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane, 1,3,5-trioxepane, 1,3,6-trioxocane and the like. Specific examples of the cyclic ether include ethylene oxide, propylene oxide and butylene oxide. In order to introduce an oxyethylene group into the polyacetal resin (A), for example, 1,3-dioxolane may be used, and in order to introduce an oxypropylene group, 1,3-dioxane may be used. For introduction, 1,3-dioxepane may be introduced.

(B) Hydrazide compound The hydrazide compound mix | blended with the polyacetal resin composition of this invention is a hydrazide compound represented by the said General formula (1).
In the above formula (1), m may be a positive integer, but when R ¹ represents an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group or a heterocyclic group. , M is usually an integer from 1 to 4. When R ¹ represents a main chain of a polymer containing —CZ ¹ Z ² —CZ ³ Z ⁴ — as a structural unit, m is usually —CZ ¹ Z ² —CZ ³ Z included in the main chain of the polymer. It is the same as the total number of single bonds in the total number of ^4- structural units.

In the general formula (1), R ¹ is an (m + n) -valent group, which is an aliphatic hydrocarbon group having 1 to 40 carbon atoms, an alicyclic hydrocarbon group having 3 to 40 carbon atoms, or 6 to 6 carbon atoms. 10 aromatic hydrocarbon group, or a heterocyclic group having 2 to 5 carbon _atoms, a main chain of the polymer containing -CH 2 -CH- as a constituent unit.

  The aliphatic hydrocarbon group may be saturated or unsaturated, and may be linear or branched.

  For example, when m + n is 1, the aliphatic hydrocarbon group is a monovalent aliphatic hydrocarbon group, and when m + n is 2, the aliphatic hydrocarbon group is a divalent aliphatic hydrocarbon group.

  Specific examples of the monovalent aliphatic hydrocarbon group include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, n-hexyl group, n-octyl group, n-decyl group, and n-dodecyl group. Linear alkyl groups such as n-hexadecyl group, n-eicosyl group, n-triacontyl group and n-tetracontyl group, branched alkyl groups such as i-propyl group, i-butyl group and t-butyl group, 1- Examples thereof include alkenyl groups such as propenyl group and 1-butenyl group, alkynyl groups such as ethynyl group and 2-propynyl group.

  Specific examples of the divalent aliphatic hydrocarbon group include alkylene groups such as a methylene group, an ethylene group, a propylene group, a butylene group, a hexylene group, an octylene group, and a decylene group.

  The alicyclic hydrocarbon group may be saturated or unsaturated. For example, when m + n is 1, the alicyclic hydrocarbon group is a monovalent alicyclic hydrocarbon group, and when m + n is 2, the alicyclic hydrocarbon group is a divalent alicyclic hydrocarbon group.

  Examples of the monovalent alicyclic hydrocarbon group include a cycloalkyl group having 3 to 40 carbon atoms and a cycloalkenyl group. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, a cyclododecyl group, a cyclohexadecyl group, a cycloeicosyl group, and a cyclotriacontyl group. , Cyclotetracontyl group, norbornyl group, adamantyl group and the like. Examples of the cycloalkenyl group include a 1-cyclohexenyl group.

  Examples of the divalent alicyclic hydrocarbon group include a cycloalkylene group having 3 to 40 carbon atoms. Examples of the cycloalkylene group include a cyclohexylene group.

  When m + n is 1, the aromatic hydrocarbon group is a monovalent aromatic hydrocarbon group, and when m + n is 2, the aromatic hydrocarbon group is a divalent aromatic hydrocarbon group.

  Specific examples of the monovalent aromatic hydrocarbon group include aryl groups such as a phenyl group and a naphthyl group.

  Examples of the divalent aromatic hydrocarbon group include arylene groups such as a phenylene group and a naphthylene group.

  A substituent may be bonded to at least a part of the carbon atoms of the aromatic hydrocarbon group. Examples of the substituent include a halogen group, a nitro group, and an alkyl group having 1 to 40 carbon atoms.

  The heterocyclic group is an (m + n) -valent group containing at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom, and from any carbon atom of the heterocyclic compound (m + n) It is formed by removing one hydrogen atom. Examples of such heterocyclic compounds include piperidine, piperazine, pyridine, triazine, imidazole, pyrrole, carbazole, pyrrolidine, luminol, uracil, creatine, urea ring, lactam, isoniazid-containing heterocyclic compounds, ethifuran, and the like. , Heterocyclic compounds containing only oxygen atoms as heteroatoms such as tetrahydrofuran and dioxane, and heterocyclic compounds containing sulfur atoms such as thiophene. Among these, a heterocyclic group containing a nitrogen atom is particularly preferable. In this case, the reactivity between the hydrazide compound and formaldehyde becomes higher, and generation of formaldehyde can be more effectively suppressed.

The main chain of the polymer may be a main chain containing —CZ ¹ Z ² —CZ ³ Z ⁴ — as a structural unit.
Here, Z ^{1 to} Z ⁴ each independently represent a single bond, a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and at least one of Z ^{1 to} Z ⁴ represents a single bond. The -C formula (1) a single bond (O) NHNH ₂ R ² and -C (O) NHNH ₃ are coupled. Specific examples of the hydrazide compound containing the main chain of such a polymer as R ¹ include, for example, poly (methacrylic acid-2-methylhydrazide), poly (acrylic acid-2-methylhydrazide), and poly (ethyleneethylacrylic acid hydrazide). ) And the like.

  As described above, m represents a positive integer, and n represents 0 or 1.

Here, n is preferably 0. In this case, the group bonded to R ¹ is only m groups having a terminal R ² and does not include a group having a hydrogen atom at the terminal. That is, the group bonded to R ¹ is only one having higher reactivity with formaldehyde. For this reason, the reactivity of the hydrazide compound (B) and formaldehyde can be made higher than that of the hydrazide compound in which m = 2 and n ≠ 0 in the general formula (1), and the generation of formaldehyde is reduced. It can be suppressed more sufficiently.

  In the general formula (1), when n is 0, m = 2 is preferable.

In this case, since the group bonded to R ¹ is only a group having higher reactivity with formaldehyde, the hydrazide compound is compared with the hydrazide compound in which m = 1 and n = 0 in the general formula (1). The reactivity between (B) and formaldehyde can be further increased, and generation of formaldehyde can be more sufficiently suppressed. In addition, since the steric hindrance is reduced and it is easy to react with formaldehyde as compared with the hydrazide compound in which m is 3 or more and n = 0 in the general formula (1), generation of formaldehyde can be more sufficiently suppressed.

R ² is a monovalent group, an aliphatic hydrocarbon group having 1 to 40 carbon atoms, an alicyclic hydrocarbon group having 3 to 40 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, carbon The heterocyclic group of number 2-5 is shown.

Examples of the aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group or heterocyclic group include the aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group or heterocyclic ring of R ^1. Among the groups, those similar to the monovalent group can be used.

R ² is preferably a linear alkyl group having 1 to 18 carbon atoms. In this case, the reactivity between the hydrazide compound represented by the general formula (1) and formaldehyde becomes higher, and the generation of formaldehyde is more effectively suppressed.

Among linear alkyl groups having 1 to 18 carbon atoms, linear alkyl groups having 1 to 3 carbon atoms are more preferable. In this case, since the steric hindrance due to R ² becomes small, the reactivity between the hydrazide compound (B) and formaldehyde becomes higher, and the generation of formaldehyde can be more effectively suppressed. A methyl group is particularly preferable. In this case, since the steric hindrance due to R ² is particularly small, the reactivity between the hydrazide compound (B) and formaldehyde is particularly high, and generation of formaldehyde can be particularly effectively suppressed.

  Specific examples of the hydrazide compound (B) represented by the general formula (1) include, for example, bis (2-methylhydrazide) oxalate, bis (2-methylhydrazide) malonate, and bis (2-methylhydrazide) adipate. ), Bis (2-methylhydrazide) sebacate, 1,10-dodecanedioic acid bis (2-methylhydrazide), 1,4-cyclohexanedioic acid bis (2-methylhydrazide), terephthalic acid bis (2-methylhydrazide) ), 2,6-naphthalenedioic acid bis (2-methylhydrazide), 7,11-octadecane-1,18-dioic acid bis (2-methylhydrazide), and the like.

  The hydrazide compound (B) represented by the general formula (1) may be used alone or in combination of two or more. The compounding quantity of a hydrazide compound (B) is 0.05-5 mass parts with respect to 100 mass parts of polyacetal resins. When the compounding quantity of a hydrazide compound (B) is less than 0.05 mass part, generation | occurrence | production of formaldehyde cannot fully be suppressed. Moreover, when the compounding quantity of a hydrazide compound (B) is 5 mass parts or more, a bleed out will generate | occur | produce at the time of a shaping | molding process, and a metal mold | die will be contaminated. It is preferable that the compounding quantity of a hydrazide compound (B) is 0.1-3 mass parts, and it is more preferable that it is 0.1-1 mass part.

In addition, the hydrazide compound (B) represented by the general formula (1) can be obtained by reacting a carboxylic acid or a carboxylic acid ester with a hydrazine compound. At this time, R ¹ (COOH) _{m + n} is used as the carboxylic acid, R ¹ (COOY) _{m + n} is used as the carboxylic acid ester, and NH ₂ NHR ² is used as the hydrazine compound. Here, in carboxylic acid ester R ¹ (COOY) _{m + n} , Y represents an alkyl group, a cycloalkyl group, an aryl group, or a heterocyclic group. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Of these, a methyl group is most preferable. Examples of the cycloalkyl group include a cyclopentyl group and a cyclohexyl group. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the carboxylic acid ester represented by R ¹ (COOY) _{m + n} include dimethyl oxalate, dimethyl malonate, dimethyl adipate, dimethyl sebacate, dimethyl 1,10-dodecanedioate, and dimethyl 1,4-cyclohexanedioate. Dimethyl terephthalate, dimethyl 2,6-naphthalenedioate, dimethyl 7,11-octadecane-1,18-dioate, and the like. Examples of the hydrazine compound represented by NH ₂ NHR ² include 2-alkylhydrazines such as 2-methylhydrazine, 2-ethylhydrazine, and 2-propylhydrazine. In the case where n is 1 in the general formula (1), NH ₂ NH ₂ may be added when the carboxylic acid or carboxylic acid ester is reacted with the hydrazine compound.

  The polyacetal resin composition of this invention may contain at least 1 sort (s) of a heat stabilizer (C), a mold release agent (D), and a weathering stabilizer (E) as needed. Hereinafter, the heat stabilizer (C), the release agent (D) and the weathering stabilizer (E) will be described in detail.

(C) Heat stabilizer Although a heat stabilizer is not specifically limited, As a heat stabilizer, a hindered phenol compound or a triazine compound is used preferably. These may be blended singly or in combination of two or more. In this case, the generation of formaldehyde is further effectively suppressed.

The hindered phenol (sterically hindered phenol) compound is a compound having at least one structure in the molecule having a substituent at the ortho position with respect to the phenolic hydroxyl group represented by the following general formula (3).

In the general formula (3), R ⁴ and R ⁵ each independently represent a substituted or unsubstituted alkyl group.

Examples of the alkyl group represented by R ⁴ and R ⁵ include those having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, and an amyl group. Of these, a bulky branched alkyl group such as a t-butyl group is preferable, and at least one of R ⁴ and R ⁵ is preferably such a branched alkyl group. As the substituted alkyl group, a group in which a hydrogen atom of an unsubstituted alkyl group is substituted with a halogen atom such as chlorine can be used.

  Examples of the hindered phenol compound used in the present invention include 2,2′-methylene-bis (4-methyl-6-tert-butylphenol) and 4,4′-methylene-bis (2,6-di-tert-butylphenol). ), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 3,5-di-tert-butyl-4-hydroxybenzyldimethyl Amines, distearyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate, diethyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate, 2,6,7-trioxa-1-phospha -Bicyclo [2,2,2] -oct-4-yl-methyl-3,5-di-t-butyl-4-hydroxyhydrocinnamate, 3,5-di-t-butyl-4- Roxyphenyl-3,5-distearyl-thiotriazylamine, 2- (2-hydroxy-3,5-di-t-butylphenyl) -5-chlorobenzotriazole, 2,6-di-t-butyl- 4-hydroxymethylphenol, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, N, N′-hexa Methylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,6-hexane Diol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythritol-tetrakis [3- (3,5-di-t-butyl-4- Droxyphenyl) propionate], triethylene glycol-bis [3- (3,5-dimethyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4 -Hydroxyphenyl) propionate], triethylene glycol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2'-thiodiethyl-bis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate] and the like.

Among these, a structure represented by the following general formula (4) such as N, N-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide) is preferable. A compound.

In the general formula (4), ^{R 4} and ^{R 5,} respectively, the same meanings as ^{R 4} and ^{R 5} in the general formula (3).

  Also, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythritol-tetrakis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3,5-dimethyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl- 4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2′-thiodiethyl-bis [3- (3,5 3,5-dialkyl-4-hydride in the 3-position, such as -di-t-butyl-4-hydroxyphenyl) propionate] Also preferred are esters of propionic acid and polyhydric alcohols having a roxyphenyl group.

（上記一般式（５）において、Ｒ^６、Ｒ^７、Ｒ^８はそれぞれ独立して、水素原子、ハロゲン原子、水酸基、メルカプト基、アルキル基、アラルキル基、アリール基、シクロアルキル基、アミノ基または置換アミノ基を示し、その少なくとも一つは、アミノ基、または置換アミノ基を表す。） The triazine compound is basically a substituted triazine having a structure represented by the following general formula (5), or an initial polycondensate of the substituted triazine and formaldehyde.

(In the general formula (5), R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, halogen atom, hydroxyl group, mercapto group, alkyl group, aralkyl group, aryl group, cycloalkyl group, amino group or A substituted amino group, at least one of which represents an amino group or a substituted amino group.

  Specific examples of the amino-substituted triazine compound or the initial polycondensate of amine-substituted triazine compound and formaldehyde include, for example, guanamine, melamine, N-butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N, N -Diallylmelamine, N, N ', N "-triphenylmelamine, N, N', N" -trimethylolmelamine, benzoguanamine, 2,4-diamino-6-methyl-sym-triazine, 2,4-diamino- 6-butyl-sym-triazine, 2,4-diamino-6-benzyloxy-sym-triazine, 2,4-diamino-6-butoxy-sym-triazine, 2,4-diamino-6-cyclohexyl-sym-triazine 2,4-diamino-6-chloro-sym-triazine, 2,4-diamidine 6-mercapto -sym- triazine, ammeline (N, N, N ', N'- tetra-cyanoethyl benzoguanamine), or the initial weight condensate thereof with formaldehyde. Among these, melamine, methylol melamine, benzoguanamine, and a water-soluble melamine-formaldehyde resin are particularly preferable.

  It is preferable that the compounding quantity of a heat stabilizer is 0.01-3 mass parts with respect to 100 mass parts of polyacetal resin, It is more preferable that it is 0.05-2 mass parts, 0.1-1 mass part More preferably it is. When the blending amount of the heat stabilizer is 0.01 to 3 parts by mass, the thermal decomposition of the polyacetal resin is more effective than when the blending amount of the heat stabilizer (C) is less than 0.01 parts by mass. And the generation of formaldehyde is more effectively suppressed. Moreover, compared with the case where the compounding quantity of a heat stabilizer (C) exceeds 3 mass parts, the mechanical characteristic of a polyacetal resin composition can be improved more.

(D) Release agent Although a release agent is not specifically limited, As a release agent, polyethylene, silicone oil, a fatty acid, fatty acid ester, or a fatty acid metal salt is used preferably. These may be blended singly or in combination of two or more. In this case, contamination of the mold during the molding process is further effectively suppressed.

  Examples of the polyethylene include low molecular weight polyethylene, low molecular weight polyethylene copolymer, and modified polyethylene wax in which a polar group is introduced by oxidative modification or acid modification thereof. The number average molecular weight of polyethylene is preferably 500 to 15000, more preferably 1000 to 10,000.

  Polyethylene wax such as low molecular weight polyethylene and low molecular weight polyethylene copolymer is a method of directly polymerizing ethylene or ethylene and α-olefin using a Ziegler catalyst, a method of obtaining high molecular weight polyethylene or a by-product during the production of the copolymer Further, it can be produced by a method of thermally decomposing a high molecular weight polyethylene or copolymer. Such polyethylene wax is preferably a copolymer type polyethylene wax of 50 to 99 mol% of ethylene and 1 to 50 mol% of an α-olefin, and a particularly preferable polyethylene wax is a polyethylene wax in which the α-olefin is polypropylene.

  Oxidation-modified polyethylene wax is obtained by treating polyethylene wax with peroxide or oxygen to introduce polar groups such as carboxyl groups and hydroxyl groups. Acid-modified polyethylene wax is introduced with polar groups such as carboxyl groups and sulfonic acid groups by treatment with inorganic acids, organic acids or unsaturated carboxylic acids in the presence of peroxide or oxygen if necessary. It is. These polyethylene waxes are commercially available under the names of general type high density polyethylene wax, general type low density polyethylene wax, low oxidation type polyethylene wax, high oxidation type polyethylene wax, acid-modified type polyethylene wax or special monomer modified type. And can be easily obtained.

  Examples of silicone oil include silicone oil made of polydimethylsiloxane, silicone oil in which a part of methyl group of polydimethylsiloxane is substituted with phenyl group, part of methyl group of polydimethylsiloxane is hydrogen or 2 or more carbon atoms Silicone oil substituted with alkyl group, silicone oil with polydimethylsiloxane partially substituted with halogenated phenyl group, silicone oil with polydimethylsiloxane partially substituted with fluoroester group , Epoxy-modified silicone oils such as polydimethylsiloxane having epoxy groups, amino-modified silicone oils such as polydimethylsiloxane having amino groups, and alkylaralkylsilyls such as dimethylsiloxane and phenylmethylsiloxane Oil, polyether-modified silicone oil such as polydimethylsiloxane having a structure in which a part of methyl group of dimethylsiloxane unit is substituted with polyether, dimethyl in which part of methyl group of dimethylsiloxane unit is substituted with polyether Examples thereof include alkylaralkyl polyether-modified silicone oils such as a polymer of siloxane and phenylmethylsiloxane.

  Examples of the fatty acid include saturated or unsaturated fatty acids having 12 or more carbon atoms. Examples of fatty acids are lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid , Laccelic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, arachidonic acid, cetreic acid, erucic acid and the like. The fatty acid is preferably a saturated fatty acid having 12 to 22 carbon atoms.

  Examples of the fatty acid ester include fatty acid esters of a fatty acid having 5 to 32 carbon atoms and a monovalent or polyhydric alcohol having 2 to 30 carbon atoms. As fatty acids, caproic acid, caprylic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, palmitic acid, stearic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid and other saturated fatty acids, or oleic acid And unsaturated fatty acids such as elaidic acid, linoleic acid, linolenic acid, arachidonic acid, pladicic acid, erucic acid, ricinoleic acid and the like. Examples of the alcohol include monohydric alcohols such as propyl, isopropyl, butyl, octyl, capryl, lauryl, myristyl, stearyl, and behenyl, and polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, glycerin, pentaerythritol, and sorbitan. . The fatty acid ester is preferably a fatty acid ester of a fatty acid having 12 to 22 carbon atoms and a monovalent or polyhydric alcohol having 2 to 22 carbon atoms.

  The fatty acid metal salt is a salt of a higher fatty acid and a metal, and examples of the higher fatty acid include stearic acid, oleic acid, octanoic acid, lauric acid, behenic acid, and ricinoleic acid. Examples of the metal include zinc, calcium, magnesium, nickel, copper and the like.

  The compounding amount of the release agent is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 2.5 parts by mass, and 0.05 to 2 parts by mass with respect to 100 parts by mass of the polyacetal resin. More preferably, it is part. When the compounding amount of the release agent is 0.01 to 3 parts by mass with respect to 100 parts by mass of the polyacetal resin, molding is performed compared to the case where the compounding amount of the mold release agent (D) is less than 0.01 parts by mass Mold contamination during processing is more effectively suppressed. Moreover, compared with the case where the compounding quantity of a mold release agent (D) exceeds 3 mass parts, the mechanical characteristic of a polyacetal resin composition can be improved more.

(E) Anti-smudge stabilizer It is preferable that an anti-smudge stabilizer is further blended in the polyacetal resin composition of the present invention. In this case, generation of formaldehyde can be more effectively suppressed. As the anti-mold stabilizer, a light stabilizer or an ultraviolet absorber is preferably used. As the light stabilizer, hindered amine light stabilizers are preferably used, and those represented by the following general formula (2) are particularly preferably used.

In the above formula, R ³ represents an organic group in which the bond to the nitrogen atom is a carbon atom, X represents an organic group bonded to the 4-position of the piperidyl group via an oxygen atom or a nitrogen atom, or a hydrogen atom.

Examples of R ³ include a linear or branched alkyl group having 1 to 10 carbon atoms. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, a t-butyl group, a hexyl group, an octyl group, and a decyl group. Of these, a methyl group is preferred.

  Specific examples of preferred hindered amine light stabilizers include, for example, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, 1- [2- {3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, Tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, 1,2,2,6,6-pentamethyl-4-piperidyl and tridecyl- 1,2,3,4-butanetetracarboxylate (part of four ester parts of butanetetracarboxylate is 1,2,2,6,6-pentamethyl-4-piperidyl A mixture of compounds in which the other is a tridecyl group), 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β, β-tetra Methyl-3,9 (2,4,8,10-tetraoxaspiro [5,5] udencan) -condensate with diethanol, dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl- 1-piperidineethanol condensate, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, N, N ′, N ″, N ″ ″-tetrakis- (4,6-bis- (butyl -(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, bis (1,2, 2,6,6-pentamethyl-4-pi Peridyl) [[3,5-bis (1,1 dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate.

  The above anti-cracking stabilizers may be blended alone or in combination of two or more. The blending amount of the anti-glare stabilizer is preferably 0.01 to 3 parts by mass, more preferably 0.03 to 2 parts by mass, and 0.05 to 1 part by mass with respect to 100 parts by mass of the polyacetal resin. More preferably. When the blending amount of the weathering stabilizer is 0.01 to 3 parts by mass, the generation of formaldehyde can be more effectively suppressed as compared with the case where the blending amount is out of the above range.

  In addition to the above components (A) to (E), the polyacetal resin composition includes an antistatic agent such as an antioxidant, a coloring agent, a nucleating agent, a plasticizer, a fluorescent brightening agent, a sliding agent, polyethylene glycol, and glycerin. An additive such as an agent and a higher fatty acid salt may be further blended.

  In the polyacetal resin composition of the present invention, for example, the generation of formaldehyde is sufficiently suppressed. Therefore, as a countermeasure against so-called sick house syndrome, automobile interior parts, interior parts such as houses (hot water mixing plugs, etc.), clothing parts (fasteners) , Belt buckles, etc.), building material applications (piping, pump parts, etc.), and machine parts (gears, etc.).

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example.

  The materials used in Examples and Comparative Examples are as follows.

(A) Polyacetal resin (POM)
An acetal copolymer obtained by copolymerizing trioxane and 1,3-dioxolane so that the content of 1,3-dioxolane in POM is 4.2% by mass, and having a melt index (ASTM-D1238) Standard: 190 ° C., 2.16 kg) is 10.5 g / 10 min. Acetal copolymer

(B) Hydrazide Compound B-1: Bis (2-methylhydrazide) oxalate
B-2: Malonic acid bis (2-methylhydrazide)
B-3: Adipic acid bis (2-methylhydrazide)
B-4: Sebacic acid bis (2-methylhydrazide)
B-5: 1,10-dodecanedioic acid bis (2-methylhydrazide)
B-6: 1,4-cyclohexanedioic acid bis (2-methylhydrazide)
B-7: Bis (2-methylhydrazide) terephthalate
B-8: 2,6-naphthalenedioic acid bis (2-methylhydrazide)
B-9: Sebacic acid dihydrazide B-10: 2,6-naphthalenedioic acid dihydrazide

(C) Heat stabilizer C-1 (hindered phenol compound): Irganox 245, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], manufactured by BASF C-2 (triazine compound): Melamine, manufactured by Mitsui Chemicals, Inc.

(D) Molding agent trade name “Kao Wax EB-P”, ethylenebisstearylamide, manufactured by Kao Corporation

(E) Anti-glare stabilizer trade name “Tinuvin 622”, butanedioic acid 1- [2- (4-hydroxy-2,2,6,6-tetramethylpyridino) ethyl], manufactured by BASF

[Production of polyacetal resin composition]
(Examples 1-15 and Comparative Examples 1-7)
A super mixer manufactured by Kawada Seisakusho Co., Ltd. was blended in the proportions shown in Tables 1 to 3 for polyacetal resin (A), hydrazide compound (B), heat stabilizer (C), mold release agent (D), and anti-mold stabilizer (E). After mixing uniformly using a biaxial extruder (PCM-30 manufactured by Ikekai Tekko Co., Ltd., screw diameter 30 mm) and melt-kneading under the conditions of a screw rotation speed of 120 rpm and a cylinder set temperature of 190 ° C. The pellets of the polyacetal resin composition were manufactured by extruding into strands and cutting with a pelletizer. In Tables 1 to 3, the unit of the blending amount is part by mass.

[Characteristic evaluation]
(1) Inhibitory effect of formaldehyde generation The inhibitory effect of formaldehyde generation was measured based on the amount of formaldehyde generated and measured.

The amount of formaldehyde generated was determined as follows.
<Fabrication of flat specimen>
First, pellets of the polyacetal resin compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 7 were used at a cylinder temperature of 215 ° C. and a mold temperature of 80 ° C. using an injection molding machine PS-40 manufactured by Nissei Plastic Industry Co., Ltd. Injection molding was performed to prepare a 100 mm × 40 mm × 2 mm flat plate test piece.
<Measurement of formaldehyde generation>
On the day after the production of the flat test piece, the flat test piece was subjected to the following procedure in accordance with the method described in German Automobile Manufacturers Association Standard VDA275 (automobile interior parts-determination of formaldehyde emission by the revised flask method). The amount of formaldehyde generated was measured by the method described above.
(I) First, 50 ml of distilled water was put in a polyethylene container, the lid was closed with the flat plate test piece suspended in the air, and the container was heated at 60 ° C. for 3 hours in a sealed state.
(Ii) Subsequently, after leaving it to stand at room temperature for 60 minutes, a flat plate test piece was taken out.
(Iii) The amount of formaldehyde absorbed in distilled water in a polyethylene container was measured by an acetylacetone colorimetric method with a UV spectrometer, and the value obtained by dividing the amount of formaldehyde by the mass of POM in the flat plate test piece was the amount of formaldehyde generated It was. The results are shown in Tables 1-3.

In Tables 1 to 3, the pass / fail criteria for the formaldehyde generation suppression effect were as follows.
Formaldehyde generation amount is 2.5 μg / g-POM or less: Acceptable formaldehyde generation amount is more than 2.5 μg / g-POM: Fail

(2) Mold contamination suppression effect The mold contamination suppression effect was evaluated as follows. First, pellets of the polyacetal resin compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 7 were molded using a so-called drop mold using a mini mat M8 / 7A molding machine manufactured by Sumitomo Heavy Industries, Ltd. 3000 shots were continuously formed at a temperature of 200 ° C. and a mold temperature of 80 ° C. After the molding, the state of the inner wall surface of the mold was observed with the naked eye. Here, the acceptance criteria regarding the mold contamination suppression effect were as follows.

A: Almost little mold deposits and very good mold contamination suppression effect B: Although there are some mold deposits, mold contamination suppression effect is good C: Many mold deposits prevent mold contamination suppression effect Is bad

Here, A and B were accepted, and C was rejected. The results are shown in Tables 1-3.

  As shown in Tables 1 to 3, it was found that Examples 1 to 15 all met the acceptance criteria in terms of formaldehyde generation suppression and mold contamination suppression. On the other hand, it was found that all of Comparative Examples 1 to 7 did not satisfy the acceptance criteria in terms of formaldehyde generation amount or mold contamination suppression.

  Therefore, according to the polyacetal resin composition of this invention, it was confirmed that generation | occurrence | production of formaldehyde and contamination of the metal mold | die at the time of a shaping | molding process can fully be suppressed.

Claims (12)

A polyacetal resin composition in which 0.05 to 5 parts by mass of the hydrazide compound (B) represented by the following general formula (1) is blended with respect to 100 parts by mass of the polyacetal resin (A).

(In the above formula, m represents a positive integer, n represents 0 or 1. R ¹ is a (m + n) -valent group, an aliphatic hydrocarbon group having 1 to 40 carbon atoms, 3 to 3 carbon atoms, Polymer containing 40 alicyclic hydrocarbon group, 6 to 10 carbon aromatic hydrocarbon group, 2 to 5 carbon heterocyclic group, or -CZ ¹ Z ² -CZ ³ Z ⁴ -as a structural unit In the case where m = 1 and n = 1, R ¹ may be a single bond, and in the case where m = 1 and n = 0, R ¹ may be a hydrogen atom. R ² is a monovalent group, an aliphatic hydrocarbon group having 1 to 40 carbon atoms, an alicyclic hydrocarbon group having 3 to 40 carbon atoms, an aromatic hydrocarbon group having 6 to 10 carbon atoms, carbon are each ^.Z 1 to Z ⁴ indicating the number 2-5 heterocyclic group independently represents a single bond, a hydrogen atom or an alkyl group having 1 to 10 carbon ^atoms, less of Z 1 to Z ⁴ Both one is a single bond.) The polyacetal resin composition according to claim 1, wherein R ² in the general formula (1) is a linear alkyl group having 1 to 18 carbon atoms. The polyacetal resin composition according to claim ² , wherein R ² in the general formula (1) is a methyl group.   In the said General formula (1), it is n = 0, The polyacetal resin composition as described in any one of Claims 1-3.   The polyacetal resin composition according to claim 4, wherein m = 2 in the general formula (1).   The polyacetal resin composition according to any one of claims 1 to 5, wherein 0.01 to 3 parts by mass of a heat stabilizer (C) is blended with 100 parts by mass of the polyacetal resin.   The polyacetal resin composition according to claim 6, wherein the heat stabilizer (C) is at least one heat stabilizer selected from the group consisting of a hindered phenol compound and a triazine compound.   The polyacetal resin composition according to any one of claims 1 to 7, wherein 0.01 to 3 parts by mass of a release agent (D) is blended with respect to 100 masses of the polyacetal resin.   The polyacetal resin composition according to claim 8, wherein the release agent (D) is at least one release agent selected from the group consisting of polyethylene, silicone oil, fatty acid, fatty acid ester, and fatty acid metal salt.   The polyacetal resin composition according to any one of claims 1 to 9, wherein 0.01 to 3 parts by mass of the anti-stabilizer (E) is blended with respect to 100 parts by mass of the polyacetal resin.   The polyacetal resin composition according to claim 10, wherein the weathering stabilizer (E) is at least one weathering stabilizer selected from the group consisting of a hindered amine light stabilizer and an ultraviolet absorber. The polyacetal resin composition according to claim 11, wherein the hindered amine light stabilizer is a hindered amine light stabilizer represented by the following general formula (2).

(In the above formula, R ³ represents an organic group in which the bond to the nitrogen atom is a carbon atom, and X represents an organic group or hydrogen atom that is bonded to the 4-position of the piperidyl group via an oxygen atom or a nitrogen atom.)