Polyacetal resin composition

Abstract

The object of the present invention is to provide a polyacetal resin composition that can suppress the amount of formaldehyde released from resin products in humid and dry environments and does not generate mold deposits during molding. [Solution] The polyacetal resin composition of the present invention comprises a polyacetal resin, a form-catching agent containing the compound of formula (1), and a nitrogen-containing compound. [Formula 1] TIFF2026103840000007.tif34132

Description

[Technical Field]

[0001] This invention relates to a polyacetal resin composition. [Background technology]

[0002] Polyacetal resin is a material with excellent rigidity, strength, toughness, sliding properties, and creep resistance, and is used in a wide range of applications. Specifically, it is widely used as a resin material for mechanical components such as automotive parts, electrical and electronic components, and industrial parts.

[0003] Polyacetal resins decompose under the influence of heat, light, oxygen, acids, and alkalis, releasing formaldehyde. The released formaldehyde can cause deterioration of the indoor environment, harm to users' health, and degrade the performance of precision equipment. For this reason, it is required to strictly control the amount of formaldehyde released, especially in household appliances used in living spaces, interior parts of automobiles, and transport containers for precision equipment such as semiconductors, as well as electronic equipment components.

[0004] Traditionally, automotive applications have been evaluated under humid conditions (e.g., the VDA275 method). However, in recent years, there has been an increase in applications for casings and containers of industrial and electronic equipment used in dry environments. Therefore, there is a growing need to suppress formaldehyde emissions in these environments as well. In particular, casings and containers used for transporting precision equipment such as semiconductors require high levels of formaldehyde emission suppression in both humid and dry environments.

[0005] One known method for suppressing formaldehyde release from polyacetal resins is to add formaldehyde-reactive substances. However, since polyacetal resins are easily decomposed by acids and alkalis, there is a need for formaldehyde scavenging agents that suppress formaldehyde release without decomposing the polyacetal resin.

[0006] Furthermore, due to its high crystalline nature, polyacetal resin is difficult to mix with other substances. This can lead to bleed-and-aggregate additives during molding, contaminating the mold. This type of mold deposit, known as mold deposit, reduces productivity, and its suppression is therefore crucial.

[0007] Furthermore, a phenomenon called bleed-out is known, in which additives seep out from the surface of resin products after molding. Bleed-out not only negatively affects the appearance and surface design of resin products, but it can also alter the amount of additives in the product, potentially preventing it from maintaining its original performance. For these reasons, suppressing bleed-out is also required.

[0008] Therefore, it is important to select additives that are compatible with polyacetal resin and show effectiveness even in small amounts.

[0009] Conventional formaldehyde-reactive substances such as hydrazides, guanamine, urea, and amides (Patent Documents 1 and 2) can, when added in large quantities, cause mold deposits during molding or bleed-out under high temperature and humidity conditions, and may not adequately suppress formaldehyde release. Furthermore, these compounds have the problem that, at addition levels that do not cause mold deposits, they cannot adequately suppress formaldehyde release in dry environments. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2005-263921 [Patent Document 2] Japanese Patent Publication No. 2006-45331 [Overview of the project] [Problems that the invention aims to solve]

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide a polyacetal resin composition that can suppress the generation of formaldehyde during production, during molding, and from resin products, does not generate mold deposits during molding, and has a reduced formaldehyde emission amount in both wet and dry environments of the resin product.

Means for Solving the Problems

[0012] As a result of intensive studies by the present inventors, when a compound having a structure represented by the following formula (1) and a specific nitrogen-containing compound are added to a polyacetal resin, the formaldehyde generated in the polyacetal resin is well captured, and the formaldehyde emission amount during production, during molding, and in both wet and dry environments of the resin product can be reduced. In particular, the formaldehyde emission amount in a dry environment can be reduced. Furthermore, the compound having the above structure is compatible with the polyacetal resin and is unlikely to become a mold deposit, and thus the present invention has been completed.

Chemical formula

[0013] [1] A polyacetal resin (A), A formaldehyde catcher agent (B) containing a compound (b1) having a structure represented by the following formula (1), and A nitrogen-containing compound (C), A polyacetal resin composition, wherein the nitrogen-containing compound (C) is at least one selected from the group consisting of a hydantoin compound, a ureido compound, and a hydrazide compound.

Chemical formula

Advantages of the Invention

[0014] Since the polyacetal resin composition of the present invention has the above configuration, it can suppress the generation of formaldehyde during production and the like, and no mold deposit occurs during molding, and it can suppress the formaldehyde emission amount of resin products in a wet environment and a dry environment.

Embodiments for Carrying Out the Invention

[0015] It should be noted that there seems to be a redundant "、" in the original text around ID=18 which is retained in the translation for consistency with the original. If this is an error in the original, it may need to be corrected in the source material.The following describes in detail an embodiment for carrying out the present invention (hereinafter referred to as "this embodiment"). This embodiment is an example for explaining the present invention, and the present invention is not limited to this embodiment. That is, the present invention can be modified in various ways without departing from its essence.

[0016] <Polyacetal resin composition> The polyacetal resin composition of this embodiment comprises a polyacetal resin (A), a form catcher agent (B) containing a compound (b1) having a structure represented by the following formula (1), and a nitrogen-containing compound (C) which is at least one selected from the group consisting of hydantoin compounds, ureid compounds, and hydrazide compounds. [ka] (In formula (1), R 1 ~R 4 The wavy lines and dashes are defined as follows: In this specification, a compound having the structure represented by formula (1) may be simply referred to as "compound (B)". Also, the structure represented by formula (1) may be simply referred to as "structure". Furthermore, a nitrogen-containing compound (C), which is at least one selected from the group consisting of hydantoin compounds, ureid compounds, and hydrazide compounds, may be simply referred to as "nitrogen-containing compound (C)". The polyacetal resin composition of this embodiment may consist only of polyacetal resin (A), a form-catching agent (B), and a nitrogen-containing compound (C), or it may further contain other components.

[0017] <Polyacetal resin (A)> Examples of the polyacetal resin (A) mentioned above include polyacetal homopolymers and polyacetal copolymers. Furthermore, the polyacetal resin (A) may be used alone or in combination of two or more types.

[0018] While there are no particular limitations on polyacetal homopolymers, typical examples include those consisting substantially only of oxymethylene units, obtained by homopolymerizing formaldehyde or cyclic oligomers of formaldehyde such as its trimer (trioxane) or tetramer (tetraoxocan).

[0019] Polyacetal copolymers are not particularly limited, but examples include those obtained by copolymerizing formaldehyde or a cyclic oligomer of formaldehyde, such as its trimer (trioxane) or tetramer (tetraoxocan), with a comonomer, or those synthesized using macroinitiators, macrochain transfer agents, and macroterinary agents.

[0020] The primary structure of the polyacetal resin (A) described above may include chain-like, cyclic, or branched structures. Examples of branched structures include graft structures, ladder structures, star-shaped structures, dendrimer structures, and three-dimensional network structures. These branched structures can be synthesized using polyfunctional comonomers, polyfunctional chain transfer agents, macromonomers, etc.

[0021] Examples of monomer sequences for the above-mentioned polyacetal copolymer include random, gradient, and block sequences.

[0022] The polyacetal resin (A) described above preferably has an MFR of 1 to 50 g / 10 min, more preferably 1 to 10 g / 10 min, and even more preferably 1 to 5 g / 10 min, when measured according to ISO 1133. By setting the MFR of the polyacetal resin (A) within the above range, the amount of formaldehyde released in a dry environment can be further suppressed.

[0023] When the above polyacetal resin (A) was measured for molecular weight and molecular weight distribution in terms of polymethyl methacrylate according to ISO 16014, the peak top molecular weight was 8 × 10⁶. 4 It is preferable that the above is true, 10 × 10 4 More preferably, 15 × 104 It is more preferable that the above conditions are met. By setting the peak top molecular weight of the polyacetal resin (A) within the above range, the amount of formaldehyde released in a dry environment can be further suppressed. Furthermore, when the molecular weight and molecular weight distribution were measured in accordance with ISO 16014, the molecular weight was 5 × 10⁻¹⁰. 4 The above components are preferably present in an amount of 70% by mass or more, and preferably 85% by mass or more, relative to 100% by mass of the polyacetal resin (A). Molecular weight in polyacetal resin (A) is 5 × 10 4 By setting the above components within the specified range, the amount of formaldehyde released in a dry environment can be further suppressed.

[0024] The method for producing the polyacetal resin (A) described above is not particularly limited, but for example, it can be produced by known polymerization methods. Examples of such polymerization methods include bulk polymerization and solution slurry polymerization, and both batch and continuous methods are possible. For bulk polymerization, for example, self-cleaning kneaders such as cone kneaders and twin-screw continuous extruders are used. For solution slurry polymerization, reaction vessels equipped with stirring mechanisms are used.

[0025] As the polymerization catalyst for the polyacetal resin (A) described above, an anionic polymerization catalyst or a cationic polymerization catalyst can be used. Examples of anionic polymerization catalysts include metallic sodium and onium salts. Examples of cationic polymerization catalysts include Lewis acids and protic acids.

[0026] The polyacetal resin (A) described above is prone to decomposition in its polymerized state and is therefore used after end stabilization. Methods of end stabilization include, for example, thermal decomposition to remove unstable ends in the molten state, or reacting with other compounds to alter the end structure.

[0027] The mass ratio of the polyacetal resin (A) to 100% by mass of the polyacetal resin composition in this embodiment is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. It may also be 95% by mass or less, 99% by mass or less, or less than 100% by mass.

[0028] The formaldehyde emission amount of the polyacetal resin composition of this embodiment in a humid environment is preferably less than 3 μg per gram of resin product, and more preferably 1.5 μg or less. The amount of formaldehyde released can be measured by the method described in the examples below.

[0029] The formaldehyde emission amount of the polyacetal resin composition of this embodiment under dry conditions is preferably less than 0.2 μg per gram of resin product, and more preferably 0.1 μg or less. The amount of formaldehyde released can be measured by the method described in the examples below.

[0030] <Formaldehyde catcher (B)> The form-catching agent (B) contains compound (b1). Compound (b1) is a compound having the structure represented by the following formula (1). [ka]

[0031] The above R 1 ~R 3 Each of these is independently selected from the group of substituents consisting of hydrogen, alkyl groups, alkoxy groups, and alkylthio groups. 1 , R 2 , and R 3 Preferably, one or more of the substituents have 10 or fewer carbon atoms. 1 , R 2 , and R 3 It is even more preferable that all substituents have 10 or fewer carbon atoms. Examples of the alkyl groups mentioned above include alkyl groups having 1 to 10 carbon atoms, such as methyl groups and ethyl groups (preferably alkyl groups having 1 to 5 carbon atoms, and more preferably alkyl groups having 1 to 2 carbon atoms). The alkyl groups may be linear or branched. Examples of the alkoxy group mentioned above include a structure in which an alkyl group having 1 to 10 carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms) is bonded to an oxygen atom. Examples of the alkylthio group mentioned above include structures in which an alkyl group having 1 to 10 carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms) is bonded to a sulfur atom. The above R 1 ~R 3 From the viewpoint of suppressing the generation of mold deposits (MDs), the number of carbon atoms is preferably 10 or less, and more preferably 5 or less.

[0032] The above R 4 This is one of the substituents selected from the group consisting of hydrogen, a hydroxyl group, an alkyl group, an alkoxy group, and an alkylthio group. Examples of the alkyl groups mentioned above include alkyl groups having 1 to 10 carbon atoms, such as methyl groups and ethyl groups (preferably alkyl groups having 1 to 5 carbon atoms, and more preferably alkyl groups having 1 to 2 carbon atoms). The alkyl groups may be linear or branched. Examples of the alkoxy group mentioned above include a structure in which an alkyl group having 1 to 10 carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms) is bonded to an oxygen atom. Examples of the alkylthio group mentioned above include structures in which an alkyl group having 1 to 10 carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms) is bonded to a sulfur atom.

[0033] The above R 1 and R 2 From the viewpoint of further suppressing formaldehyde emission in dry environments, hydrogen atoms are preferred.

[0034] The above R 3From the viewpoint of further suppressing formaldehyde emission in a dry environment, it is preferable that the atom be a hydrogen atom or an alkyl group, and more preferably an alkyl group having 3 or fewer carbon atoms.

[0035] The above R 4 From the viewpoint of further suppressing formaldehyde release in a dry environment, it is preferable that the group be an alkyl group or an alkoxy group.

[0036] The above structure is R within the structure 3 and R 4 However, they may have a ring structure linked to each other via linking groups. 3 and R 4 One form in which they are linked to each other via a linking group is, for example, R 3 and R 4 One example is a form in which the hydrogen atoms in the middle are substituted at both ends of the linking group. The linking group may have a structure consisting of an alkylene group, or a linking group containing an ether group or a thioether group between alkylene groups. Furthermore, the linking group and R 3 and R 4 The structure may include an oxygen atom or a sulfur atom between the groups. That is, the linking group may be a divalent group selected from the group consisting of alkylene groups, ether groups, and thioether groups, or it may be a divalent group formed by linking a combination of divalent groups including one or more selected from alkylene groups, ether groups, and thioether groups. Examples of the above linking group include alkylene groups, ether groups, thioether groups, alkylene oxy groups, alkylene sulfanyl groups, alkylene ether alkylene groups, alkylentio ether alkylene groups, oxyalkylene oxy groups, sulfanylalkylene sulfanyl groups, and oxyalkylene sulfanyl groups, but alkylene groups and alkylene oxy groups are preferred from the viewpoint of further suppressing formaldehyde emission in a dry environment.

[0037] In formula (1), the wavy line indicates that the bond may be in the cis or trans position relative to the nitrogen atom, with respect to the double bond. That is, in the above structure, the position of the carbonyl carbon directly connected to the carbon double bond within the structure may be in the cis or trans position relative to the nitrogen atom. Furthermore, a mixture of these structural isomers may be used.

[0038] The above compound (b1) includes 3-amino-2-propenal, 3-(dimethylamino)-2-propenal, 3-amino-2-butenal, 3-aminoacrylic acid, 3-amino-2-butenoic acid, 1-amino-1-buten-3-one, 3-aminoacrylate, 2-amino-2-penten-4-one, 2-amino-2-hexen-4-one, 2-amino-2-hepten-4-one, 2-amino-5-methyl-2-hexen-4-one, 3-amino-2-butenate methyl, 3-amino-2-butenate ethyl, 3-amino-2-butenate n-propyl, 3-amino-2-butenate isopropyl, 3-amino-2-butenate tetradecyl, 3-amino-2-butenate hexadecyl, 3-amino-2-butenate octadecyl, and S-methyl Compounds in which the above structures do not form a ring structure, such as 3-amino-2-butenthioate, S-ethyl 3-amino-2-butenthioate, methyl 3-amino-2-pentenoate, methyl 3-amino-2-hexenoate, methyl 3-amino-4-methyl-2-pentenoate, and methyl 3-(dimethylamino)-2-butenoate; Compounds in which the above structures form a ring structure, such as 3-amino-2-cyclohexen-1-one, 3-amino-2-cyclopenten-1-one, 3-amino-2-cyclohepten-1-one, 3-amino-5-methyl-2-cyclohexen-1-one, 3-amino-5,5-dimethyl-2-cyclohexen-1-one, 3-(dimethylamino)-2-cyclohexen-1-one, 3-(dimethylamino)-5,5-dimethyl-2-cyclohexen-1-one, 4-amino-2,5-dihydrofuran-2-one, 4-amino-5,6-dihydr-2H-pyran-2-one, and 4-amino-5,6-dihydr-2H-thiopyran-2-one; Examples of compounds having multiple of the above structures include 1,2-ethanediol bis(3-amino-2-butenate), 1,3-propanediol bis(3-amino-2-butenate), 1,4-butanediol bis(3-amino-2-butenate), 1,3-propanediol bis(3-amino-2-butenate), and 2,9-diamino-2,8-decadien-4,7-dione.

[0039] From the viewpoint of further suppressing formaldehyde release in a dry environment, the above compound (b1) is preferably methyl 3-amino-2-butenate, 1,4-butanediol bis(3-amino-2-butenate), or 3-amino-2-cyclohexen-1-one.

[0040] From the viewpoint of suppressing the generation of mold deposits (MD), the above compound (b1) is preferably a compound having multiple of the above structures, and 1,4-butanediol bis(3-amino-2-butenate) is more preferred.

[0041] The content of the form-catching agent (B) is preferably in the range of 0.01 parts by mass or more, and more preferably 0.03 parts by mass or more, per 100 parts by mass of polyacetal resin (A). By having a form-catching agent (B) content within the above range, it is possible to obtain molded pieces with reduced formaldehyde emissions in a dry environment.

[0042] The content of the form-catching agent (B) is preferably in the range of 0.3 parts by mass or less, more preferably 0.1 parts by mass or less, and even more preferably 0.07 parts by mass or less, per 100 parts by mass of polyacetal resin (A). By having a form-catching agent (B) content within the above range, MD formation during molding can be suppressed. The above-mentioned formaldehyde catcher agent (B) may contain other components in addition to compound (b1), as long as they do not inhibit the formaldehyde emission reduction effect. The content of compound (b1) relative to 100% by mass of the above form-catching agent (B) is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more, and may be 100% by mass.

[0043] The content of compound (b1) is preferably in the range of 0.01 parts by mass or more, and more preferably 0.03 parts by mass or more, per 100 parts by mass of polyacetal resin (A). By having a compound (b1) content within the above range, it is possible to obtain molded pieces with reduced formaldehyde emissions in a dry environment.

[0044] The content of compound (b1) is preferably in the range of 0.3 parts by mass or less, more preferably 0.1 parts by mass or less, and even more preferably 0.07 parts by mass or less, per 100 parts by mass of polyacetal resin (A). By having a compound (b1) content within the above range, MD formation during molding can be suppressed.

[0045] <Nitrogen-containing compounds (C)> The nitrogen-containing compound (C) included in this embodiment is selected from the group of compounds consisting of hydantoin compounds, ureid compounds, and hydrazide compounds. These may be used individually or in combination of two or more. In this embodiment, as the nitrogen-containing compound (C), from the viewpoint of reducing the amount of formaldehyde released in a humid environment, hydantoin compounds, ethylene urea, or aliphatic hydrazides are preferred, and ethylene urea, sebacate dihydrazide, or adipic acid dihydrazide are more preferred.

[0046] <Hydantoin compounds> The above-mentioned hydantoin compounds are not limited to those listed below, but examples include hydantoin, 5,5-dimethylhydantoin, and 5,5-diphenylhydantoin.

[0047] <Ureido compounds> The above-mentioned ureid compounds are not limited to those listed below, but examples include allantoin and ethyleneurea. Among these, allantoin or ethyleneurea is preferred, and ethyleneurea is more preferred, from the viewpoint of suppressing formaldehyde emissions in humid environments.

[0048] <Hydrazide compounds> As the above hydrazide compounds, those synthesized by the reaction of carboxylic acids (including aromatic and alicyclic) with hydrazine can be used. In the case of compounds having multiple carboxyl groups, it is sufficient if at least one carboxyl group has reacted with hydrazine. Examples of carboxylic acid mono(di)hydrazide compounds synthesized using carboxylic acids include carbodide, oxalic acid mono(di)hydrazide, malonic acid mono(di)hydrazide, succinic acid mono(di)hydrazide, glutaric acid mono(di)hydrazide, adipic acid mono(di)hydrazide, sebacate acid mono(di)hydrazide, lauric acid hydrazide, malic acid dihydrazide, tartrate dihydrazide, propionic acid hydrazide, lauric acid hydrazide, and stearate hydrazide. Examples of hydrazides include phthalate dihydrazides, isophthalate dihydrazides, terephthalate dihydrazides, 2,6-naphthalate dihydrazides, p-hydroxybenzhydrazides, 1,4-cyclohexanedicarboxylic acid dihydrazides, acetohydrazides, acrylohydrazides, maleate dihydrazides, fumarate dihydrazides, benzhydrazides, nicotinohydrazides, isonicotinohydrazides, isobutylhydrazides, and oleate hydrazides. Among these hydrazide compounds, sebacate dihydrazides and adipic acid dihydrazides are particularly preferred. The term "mono(di)hydrazide" indicates that one or both of the two carboxylic acids are hydrazed.

[0049] The nitrogen-containing compound (C) content is preferably in the range of 0.01 parts by mass or more, and more preferably 0.03 parts by mass or more, per 100 parts by mass of polyacetal resin (A). By having the nitrogen-containing compound (C) content within the above range, it is possible to obtain molded pieces with reduced formaldehyde emissions in humid environments.

[0050] The nitrogen-containing compound (C) content is preferably in the range of 0.3 parts by mass or less, more preferably 0.1 parts by mass or less, and even more preferably 0.07 parts by mass or less, per 100 parts by mass of polyacetal resin (A). By keeping the nitrogen-containing compound (C) content within the above range, the generation of mold deposits during molding can be suppressed. The amount of formaldehyde catcher (B) relative to 100% by mass of the total content of the above formaldehyde catcher (B) and nitrogen-containing compound (C) is preferably 1% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, from the viewpoint of highly suppressing both the amount of formaldehyde released in a humid environment and the amount of formaldehyde released in a dry environment.

[0051] <Other additives (D)> The polyacetal resin composition of this embodiment may contain, for example, 2 parts by mass or less per 100 parts by mass of the polyacetal resin composition, known additives other than formaldehyde catcher (B) and nitrogen-containing compound (C) (other additives (D)), to the extent that the properties of the polyacetal resin (A) are not impaired. Examples of other additives (D) include antioxidants, heat stabilizers, formic acid scavengers, weather stabilizers, mold release agents, lubricants, conductive materials, thermoplastic resins, thermoplastic elastomers, pigments and dyes, inorganic fillers and organic fillers. The above-mentioned other additives (D) may be used individually or in combination of two or more types.

[0052] Hindered phenol-based antioxidants are preferred as the antioxidants mentioned above.

[0053] The above hindered phenol antioxidants are not limited to the following, but include, for example, 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-( Examples include [3,5-di-t-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], and pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]. Among these, triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)-propionate] and pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] are preferred.

[0054] The above antioxidants may be used individually or in combination of two or more.

[0055] Examples of the above-mentioned heat stabilizers include polyamides and polyacrylamides. These heat stabilizers may be used individually or in combination of two or more types.

[0056] The above polyamides are not limited to the following, but include, for example, cyclic amide polymers such as polyamide 4, polyamide 6, polyamide 10, and polyamide 12, and copolymers thereof; and polycondensates of dicarboxylic acids and diamines. The above dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid. The above diamines include hexamethylenediamine.

[0057] The above polyacrylamide may have a polyamide 3 structure produced by a hydrogen transfer reaction, which is a side reaction during polymerization. The above polyacrylamide may have intramolecular and / or intermolecular crosslinking structures due to an imide structure produced by a deammonia reaction, which is a side reaction during polymerization. Furthermore, the above polyacrylamide may be a copolymer of acrylamide and its derivatives. Examples of derivatives of the above acrylamide include N-alkylacrylamide. Furthermore, the above polyacrylamide may be a copolymer having a crosslinking structure obtained by copolymerizing with a comonomer having multiple acrylamide groups. Examples of comonomers having multiple acrylamide groups include methylenebisacrylamide.

[0058] The formic acid scavengers mentioned above are not limited to the following, but include, for example, hydroxides, inorganic salts, carboxylates, or alkoxides of alkali metals or alkaline earth metals. For example, hydroxides of sodium, potassium, magnesium, calcium, or barium; carbonates, phosphates, silicates, borates, carboxylates, and even layered double hydroxides of the above metals.

[0059] The above-mentioned formic acid scavenger may be used individually or in combination of two or more types.

[0060] As the carboxylic acid of the above carboxylate salt, a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms is preferred. The above carboxylate salts are not limited to the following, but examples include calcium dimyristate, calcium dipalmitate, calcium distearate, calcium (myristate-palmitate), calcium (myristate-stearate), calcium (palmitate-stearate), and calcium 12-hydroxystearate, among which calcium dipalmitate, calcium distearate, and calcium 12-hydroxystearate are preferred.

[0061] The above-mentioned weather stabilizers are not limited to the following, but examples include benzotriazole compounds, oxalic acid anilide compounds, and hindered amine light stabilizers. The above weather-resistant stabilizers may be used individually or in combination of two or more types.

[0062] The above-mentioned benzotriazole compounds are not limited to the following, but examples include 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-t-butylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]benzotriazole, 2-(2-hydroxy-3,5-di-t-amylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-isoamylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis-(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, and 2-(2-hydroxy-4-octoxyphenyl)benzotriazole.

[0063] The above-mentioned oxalate anilide compounds are not limited to those listed below, but examples include 2-ethoxy-2'-ethyl oxalate anilide, 2-ethoxy-5-t-butyl-2'-ethyl oxalate anilide, and 2-ethoxy-3'-dodecyl oxalate anilide.

[0064] Hindered amine-based light stabilizers are not limited to the following, but include, for example, 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, and 4-stearyloxy-2,2,6,6-tetramethylpiperidine. Peridine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4-(ethylcarbamoyloxy)-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-piperidyl)-carbonate, bis( 2,2,6,6-tetramethyl-4-piperidyl)-oxalate, bis(2,2,6,6-tetramethyl-4-piperidyl)-malonate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis-(N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 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-piperidyloxy)-ethane, α,α'-bis(2,2,6,6-tetramethyl-4-piperidyloxy)-p-xylene, bis(2,2,6,6-tetramethyl-4-piperidyl)trylene-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,Examples include 4-tricarboxylate, 1-[2-{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy}butyl]-4-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]2,2,6,6-tetramethylpiperidine, condensates of 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, etc.

[0065] Among the above weather stabilizers, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]benzotriazole, 2-(2-hydroxy-3,5-di-t-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-t-amylphenyl)benzotriazole, bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, bis-(N-methyl Condensates of 2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 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 are preferred.

[0066] The above-mentioned mold release agent and lubricant are not limited to the following, but for example, alcohols, fatty acids and their fatty acid esters, olefin compounds with an average degree of polymerization of 10 to 500, and silicones are preferred. The above-mentioned mold release agent and lubricant may be used individually or in combination of two or more types.

[0067] The conductive agents mentioned above are not limited to the following, but include, for example, conductive carbon black, metal powder, or fibers. The above conductive agents may be used individually or in combination of two or more types.

[0068] The thermoplastic resins mentioned above are not limited to the following, but examples include polyolefin resins, acrylic resins, styrene resins, polycarbonate resins, and uncured epoxy resins. The above thermoplastic resins may be used individually or in combination of two or more types.

[0069] The thermoplastic elastomers mentioned above are not limited to the following, but examples include polyurethane elastomers, polyester elastomers, polystyrene elastomers, and polyamide elastomers. The above thermoplastic elastomers may be used individually or in combination of two or more types.

[0070] The above-mentioned pigments and dyes are not limited to the following, but examples include inorganic pigments, organic pigments and dyes, metallic pigments, fluorescent pigments, and the like. The above-mentioned pigments and dyes may be used individually or in combination of two or more types.

[0071] The inorganic pigments mentioned above refer to those commonly used for coloring resins and are not limited to those listed below, but examples include zinc sulfide, titanium dioxide, barium sulfate, titanium yellow, cobalt blue, combustion pigments, carbonates, phosphates, acetates, carbon black, and acetylene black.

[0072] The above-mentioned organic pigments and dyes are not limited to the following, but examples include condensed azo, quinone, monoazo, diazo, polyazo, anthraquinone, heterocyclic, perinone, quinacridone, thioindico, perylene, dioxazine, and phthalocyanine pigments and dyes.

[0073] It is difficult to specify the exact proportion of the above-mentioned pigments and dyes, as this varies greatly depending on the color tone, but generally, they are used in the range of 0.05 to 5 parts by mass per 100 parts by mass of polyacetal resin.

[0074] The inorganic fillers mentioned above are not limited to the following, but for example, fibrous, powder, plate-shaped, and hollow fillers can be used. The above inorganic fillers may be used individually or in combination of two or more types.

[0075] The above-mentioned fibrous fillers are not limited to the following, but include, for example, glass fibers, carbon fibers, silicone fibers, silica-alumina fibers, zirconia fibers, boron nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, and inorganic fibers such as stainless steel, aluminum, titanium, copper, and brass. Whiskers with short fiber lengths, such as potassium titanate whiskers and zinc oxide whiskers, are also included.

[0076] The above-mentioned powdered particulate fillers are not limited to the following, but include, for example, talc, carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, magnesium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, silicates such as wollastonite; metal oxides such as iron oxide, titanium oxide, and alumina; metal sulfates such as calcium sulfate and barium sulfate; carbonates such as magnesium carbonate and dolomite; and other materials such as silicon carbide, silicon nitride, boron nitride, and various metal powders.

[0077] The above-mentioned plate-shaped fillers are not limited to the following, but examples include mica, glass flakes, and various metal foils.

[0078] The hollow fillers mentioned above are not limited to the following, but examples include glass balloons, silica balloons, shirasu balloons, metal balloons, and the like.

[0079] The above-mentioned organic fillers are not limited to the following, but examples include high-melting-point organic fibrous fillers such as aromatic polyamide resins, fluororesins, and acrylic resins. The above organic fillers may be used individually or in combination of two or more types.

[0080] The inorganic and organic fillers described above may also be surface-treated with a surface treatment agent. Such surface treatment can adjust the smoothness and mechanical properties of the molded surface.

[0081] The above-mentioned surface treatment agent is not particularly limited, and conventionally known surface treatment agents can be used.

[0082] Surface treatment agents can be used, but are not limited to the following, including various coupling agents such as silane-based, titanate-based, aluminum-based, and zirconium-based agents, as well as surfactants such as resin acids, organic carboxylic acids, and salts of organic carboxylic acids. Specifically, but are not limited to the following, examples include N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, isopropyltrisstearoyl titanate, diisopropoxyaluminum ethyl acetoacetate, and n-butyl zirconate.

[0083] When the polyacetal resin composition contains (D) other additives, the content of (A) polyacetal resin in 100% by mass of the polyacetal resin composition is preferably 75% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0084] <Properties of Polyacetal Resin Composition> The polyacetal resin composition of this embodiment is preferably characterized by low formaldehyde emissions in both humid and dry environments. In other words, the smaller the product of the measured formaldehyde emissions in humid and dry environments, the more suppressed the formaldehyde emission is under all environmental conditions, which is preferable. The formaldehyde emissions in humid and dry environments can be measured by the methods described in the examples below.

[0085] The polyacetal resin composition of this embodiment is preferable from the viewpoint of moldability as the amount of mold deposit (MD) generated decreases. The amount of mold deposit (MD) generated can be measured by the method described in the examples below.

[0086] <Method for producing polyacetal resin composition> The polyacetal resin composition of this embodiment can be produced, for example, by a known melt-mixing method. For example, the polyacetal resin (A) and the compound may be mixed in a stirrer such as a Henschel mixer and then supplied to a single-screw or twin-screw melt-mixing device (extruder) for melt-mixing, or the polyacetal resin may be supplied from the upstream of a single-screw or twin-screw extruder to a molten state, and then the compound may be supplied downstream for melt-mixing.

[0087] The polyacetal resin composition of this embodiment can be used as a raw material for molded articles. It can be used in any shape, for example, injection molded articles, fibers, nonwoven fabrics, sheets, films, and shaped extruded articles.

[0088] <Applications of molded articles made from polyacetal resin compositions> The molded articles of the polyacetal resin composition of this embodiment exhibit excellent quality stability and can therefore be used as molded articles for a variety of applications. For example, they can be used for mechanical parts such as gears, cams, sliders, levers, shafts, bearings, and guides; resin parts produced by outsert molding or insert molding (chassis, tray, side plate parts); parts for printers or copiers; parts for digital cameras or digital video equipment; parts for music, video, or information equipment; parts for communication equipment; parts for electrical equipment; and parts for electronic equipment.

[0089] Furthermore, molded articles of the polyacetal resin composition of this embodiment are suitably used as automotive parts, such as fuel-related parts including gasoline tanks, fuel pump modules, valves, and gasoline tank flanges; door-related parts; seat belt-related parts; combination switch parts; and switches.

[0090] Furthermore, since the molded articles of the polyacetal resin composition of this embodiment have a highly reduced formaldehyde emission level in both humid and dry environments, they can be suitably used as transport containers for precision equipment such as semiconductors and as electronic equipment components. [Examples]

[0091] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0092] The raw materials used in the examples and comparative examples are as follows:

[0093] <Polyacetal resin (A)> Polyacetal resin homopolymer obtained by polymerizing formaldehyde (MFR = 2.0 g / 10 min, peak top molecular weight 16.7 × 10 4 , molecular weight 5×10 4 The above components (containing 89%) were used. The MFR value was measured according to ISO 1133-1 using a MELT INDEXER manufactured by Toyo Seiki, at a cylinder temperature of 190°C and a load of 2.16 kg. The molecular weight and molecular weight distribution were measured according to ISO 16014 using an HLC-8320GPC manufactured by Tosoh, at a column temperature of 40°C, as the molecular weight and molecular weight distribution in terms of polymethyl methacrylate.

[0094] <Formaldehyde catcher (B)> B-1:3-amino-2-butenate methyl (Tokyo Chemical Industries) B-2:1,4-Butanediol bis(3-amino-2-butenate) (Tokyo Chemical Industries) B-3:3-amino-2-cyclohexen-1-one (Tokyo Chemical Co., Ltd.)

[0095] <Nitrogen-containing compounds (C)> C-1: Ethylene urea (Tokyo Chemical Industries) C-2: Dihydrazide adipic acid (Tokyo Chemical Industries) C-3: Dihydrazide sebacate (Tokyo Chemical Industries) C-4: Hydantoin (Tokyo Chemical Co., Ltd.) C-5: Allantoin (Tokyo Chemical Co., Ltd.)

[0096] <(D) Other additives> D-1: Triethylene glycol-bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)-propionate] (Songwon Co., Ltd.) D-2: Acrylamide copolymer (Asahi Kasei Finechem)

[0097] The measurement and evaluation methods are as follows:

[0098] <(1) Formaldehyde emissions under humid conditions (VDA275 value)> Using an injection molding machine (Toshiba Machine IS-100GN), test specimens (100 mm × 40 mm × 3 mm flat plates) were molded from the polyacetal resin compositions obtained in the examples and comparative examples under the following conditions: mold temperature 77°C, cylinder temperature 200°C, injection pressure 35 MPa, injection time 15 seconds, and cooling time 20 seconds. The amount of formaldehyde emitted from the above test specimen was measured in accordance with the method described in German Automotive Industry Association standard VDA275. Specifically, the test specimen was suspended in a 1L polyethylene bottle containing 50mL of distilled water, ensuring it did not come into contact with the water, and then sealed. This was heated at 60°C for 3 hours and then allowed to stand at room temperature for 60 minutes. The formaldehyde in the distilled water was reacted with acetylacetone in the presence of ammonium ions, and the absorption peak at a wavelength of 412nm was measured using a UV spectrometer to determine the amount of formaldehyde emitted. The amount of formaldehyde emitted was expressed as the amount of formaldehyde per 1g of polyacetal resin (μg / g). A smaller value indicates that the amount of formaldehyde emitted is suppressed, which is preferable.

[0099] <(2) Formaldehyde emissions under dry conditions (sampling bag method values)> Using an injection molding machine (Toshiba Machine IS-100GN), test specimens (100 mm × 40 mm × 3 mm flat plates) were molded from the polyacetal resin compositions obtained in the examples and comparative examples under the following conditions: mold temperature 77°C, cylinder temperature 200°C, injection pressure 35 MPa, injection time 15 seconds, and cooling time 20 seconds. Two molded test specimens were sealed in a 10L polyvinyl fluoride sampling bag, degassed, and then 4L of nitrogen was added. The bag was heated at 65°C for 2 hours. Subsequently, 3L of nitrogen was removed from the sampling bag at a rate of 0.5ml / min, and the resulting formaldehyde was adsorbed onto a DNPH (2,4-dinitrophenylhydrazine) collection tube (Sep-Pak DNPH-Silica: Waters). Subsequently, the reaction product of DNPH and formaldehyde is collected from the DNPH collection tube using acetonitrile. The reaction product of DNPH and formaldehyde was extracted using solvent extraction and measured by high-performance liquid chromatography. The amount of formaldehyde generated was determined using a calibration curve method with a substance, and expressed as the amount of formaldehyde per 1 g of polyacetal resin (μg / g). A smaller value indicates that the amount of formaldehyde released is suppressed, which is preferable. Note that in Comparative Example 1, the amount of formaldehyde released exceeded the capacity of the DNPH collection tube, so the measured value is not shown.

[0100] <(3) Evaluation of mold deposits (MD)> Using an injection molding machine (Si30-V manufactured by Toyo Machinery & Metal Co., Ltd.), the process of creating molded pieces from the polyacetal resin compositions obtained in the examples and comparative examples was repeated under the conditions of a mold temperature of 43°C, a cylinder temperature of 200°C, an injection time of 20 seconds, and a cooling time of 20 seconds. The amount of mold deposit (MD) adhering to the mold cavity was observed after 1000 shots from the start of molding, and the mold deposit (MD) properties were evaluated according to the following criteria. ○ (Excellent): No MD (Metal Modulation) deposits were observed inside the mold cavity. △ (Good): A small amount of MD (Metal Modulation) is observed inside the mold cavity. × (Defective): A large amount of film-like MD (Metal Modulation) is observed adhering to the mold cavity.

[0101] [Examples 1-13, Comparative Examples 1-9] The mixtures shown in Table 1 were fed into a twin-screw extruder (TEM, manufactured by Shibaura Machinery), melt-kneaded at a screw rotation speed of 100 rpm and a cylinder temperature of 210°C, and then pelletized. The resulting pellets were dried for 3 hours using a hot air dryer at 80°C, and then molded and evaluated using the method described above. The evaluation results are summarized in Table 1.

[0102] [Table 1]

Claims

1. Polyacetal resin (A), A form-catching agent (B) comprising a compound (b1) having a structure represented by the following formula (1), and Contains a nitrogen-containing compound (C), A polyacetal resin composition in which the nitrogen-containing compound (C) is at least one selected from the group consisting of hydantoin compounds, ureid compounds, and hydrazide compounds. 【Chemistry 1】 (In formula (1), R １ , R ２ , and R ３ Each of these is independently selected from the substituent group consisting of hydrogen, alkyl groups, alkoxy groups, and alkylthio groups. R ４ This is one of the substituents selected from the group consisting of hydrogen, a hydroxyl group, an alkyl group, an alkoxy group, and an alkylthio group. R ３ and R ４ These may be linked to each other via linking groups, so that the structure represented by formula (1) forms a ring structure. The linking group is a divalent group formed by linking a divalent group selected from the group consisting of alkylene groups, ether groups, and thioether groups, or a combination of divalent groups containing one or more of these groups. The wavy lines indicate that the bond can be either in the cis or trans position relative to the nitrogen atom, with the double bond in between.

2. The polyacetal resin composition according to claim 1, wherein the nitrogen-containing compound (C) is at least one selected from the group consisting of ethylene urea, sebacate dihydrazide, and adipic acid dihydrazide.

3. The above-mentioned R １ , R ２ , and R ３ are all substituents having 10 or less carbon atoms. The polyacetal resin composition according to claim 1 or 2.

4. The polyacetal resin composition according to claim 1 or 2, wherein the compound (b1) is at least one selected from the group consisting of methyl 3-amino-2-butenoate, 1,4-butanediol bis(3-amino-2-butenate), and 3-amino-2-cyclohexen-1-one.

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