Polyacetal resin composition

Abstract

The present invention relates to a polyacetal resin composition. The object of the present invention is to provide a polyacetal resin composition which can suppress the amount of formaldehyde released from a resin product in a humid environment and in a dry environment, and which does not cause mold fouling at the time of molding processing. The polyacetal resin composition of the present invention comprises a polyacetal resin, a formaldehyde trapping agent comprising a compound of formula (1), and a nitrogen-containing compound.

Description

Technical Field

[0001] This invention relates to polyacetal resin compositions. Background Technology

[0002] Polyacetal resins are materials with excellent rigidity, strength, toughness, lubrication, and creep resistance, and are used in a wide range of applications. Specifically, they are widely used as resin materials for mechanical components such as automotive parts, electrical / electronic components, and industrial parts.

[0003] Polyacetal resins have the property of decomposing and releasing formaldehyde when exposed to heat, light, oxygen, acids, and alkalis. The released formaldehyde can deteriorate the indoor environment, harm the health of users, and reduce the performance of precision equipment. Therefore, strict control of formaldehyde release is required, particularly in household appliances used in living spaces, automotive interior components, and in containers for precision instruments such as semiconductors and electronic equipment components.

[0004] In automotive applications, evaluation under humid conditions (e.g., VDA275 method) has been used. However, in recent years, the use of housings and containers for industrial equipment and electronic devices in dry environments has increased. Therefore, there is also a demand for suppressing formaldehyde emissions in such environments, especially for housings and containers used in the transport of precision equipment such as semiconductors, which require high levels of formaldehyde emission suppression in both humid and dry environments.

[0005] As a method to suppress the release of formaldehyde from polyacetal resin, the addition of formaldehyde-reactive substances is known. Polyacetal resin is easily decomposed by acids, alkalis, etc., therefore, a formaldehyde scavenger is required that can suppress formaldehyde release without causing the polyacetal resin to decompose.

[0006] Furthermore, polyacetal resin has high crystallinity, making it difficult to mix with other substances. Therefore, additives sometimes seep out and aggregate during molding, contaminating the mold. This fouling on the mold, known as mold fouling, is a cause of reduced productivity, and its control is crucial.

[0007] Furthermore, a phenomenon known as exudation occurs when additives seep out onto the surface of molded resin products. Besides negatively impacting the appearance and surface design of resin products, exudation also raises concerns about variations in the dosage of additives, potentially disrupting the product's original performance. For these reasons, efforts are made to suppress exudation.

[0008] Therefore, it is also important to select additives that have good affinity with polyacetal resins and show effects in small amounts.

[0009] When large amounts of previously known formaldehyde-reactive substances such as hydrazides, guanidines, ureas, and amides are added (Patent Document 1, Patent Document 2), mold fouling sometimes occurs during molding, or leaching occurs under high temperature and humidity conditions, and sometimes the release of formaldehyde cannot be sufficiently suppressed. Furthermore, these compounds have the following problem: at levels that do not produce mold fouling, they cannot sufficiently suppress the release of formaldehyde under dry conditions.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2005-263921

[0013] Patent Document 2: Japanese Patent Application Publication No. 2006-45331 Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] The present invention was made in view of the above circumstances, and its object is to provide a polyacetal resin composition that can suppress the generation of formaldehyde during manufacturing, molding and processing and from resin products, and does not generate mold fouling during molding and processing, and suppresses the formaldehyde release of resin products in humid and dry environments.

[0016] means for solving problems

[0017] Therefore, the inventors conducted in-depth research and found that when a compound having the structure represented by the following formula (1) and a specific nitrogen-containing compound are added to a polyacetal resin, formaldehyde generated in the polyacetal resin can be effectively captured, and the formaldehyde release during manufacturing, molding and processing and in both humid and dry environments of the resin product can be reduced, especially the formaldehyde release in dry environments. Moreover, the compound having the above structure has good affinity with the polyacetal resin and is not easy to become mold fouling, thus completing the present invention.

[0018]

[0019] That is, the present invention is as follows.

[0020] [1] A polyacetal resin composition, wherein the polyacetal resin composition comprises: polyacetal resin (A),

[0021] Formaldehyde scavenger (B) comprising a compound (b1) having a structure represented by the following formula (1), and

[0022] Nitrogen-containing compounds (C).

[0023] The nitrogen-containing compound (C) is at least one selected from the group consisting of hydantoin compounds, ureido compounds, and hydrazide compounds.

[0024]

[0025] In equation (1), R 1 R 2 and R 3 Each can be independently selected from any one of the substituent groups consisting of hydrogen, alkyl, alkoxy, and alkylthio groups.

[0026] R 4 The substituent is selected from any one of the substituent groups consisting of hydrogen, hydroxyl, alkyl, alkoxy, and alkylthio groups.

[0027] R 3 and R 4 They can be interconnected via linking groups to form a ring structure, as represented by equation (1).

[0028] The linking group is a divalent group selected from the group consisting of alkylene, ether, and thioether groups, or a divalent group formed by linking together one or more of these divalent groups.

[0029] The bond represented by the wavy line indicates a double bond, and it can be either cis or trans relative to the nitrogen atom.

[0030] [2] The polyacetal resin composition according to [1], wherein the nitrogen-containing compound (C) is at least one selected from the group consisting of ethylene urea, sebacate dihydrazide and adipate dihydrazide.

[0031] [3] The polyacetal resin composition according to [1] or [2], wherein the R 1 R 2 and R 3 All of them are substituents with 10 or fewer carbon atoms.

[0032] [4] The polyacetal resin composition according to any one of [1] to [3], 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-butenoate) and 3-amino-2-cyclohexene-1-one.

[0033] Invention Effects

[0034] The polyacetal resin composition of the present invention has the above-described structure, thus it can suppress the generation of formaldehyde during manufacturing, etc., and will not generate mold fouling during molding and processing, and can suppress the formaldehyde release of resin products in humid and dry environments. Detailed Implementation

[0035] The following is a detailed description of a method for implementing the present invention (hereinafter referred to as "this embodiment"). It should be noted that this embodiment is merely an example for illustrating 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 spirit.

[0036] <Polyacetal Resin Composition>

[0037] The polyacetal resin composition of this embodiment comprises a polyacetal resin (A), a formaldehyde scavenger (B) comprising a compound (b1) having a structure represented by the following formula (1), and a nitrogen-containing compound (C) being at least one selected from the group consisting of hydantoin compounds, urea compounds and hydrazide compounds.

[0038]

[0039] (In equation (1), R) 1 ~R 4 (The wavy line is defined as follows.)

[0040] It should be noted that, in this specification, a compound having a structure represented by formula (1) is sometimes simply referred to as "compound (B)". In addition, a structure represented by formula (1) is sometimes simply referred to as "structure". In addition, a nitrogen-containing compound (C) that is at least one selected from the group consisting of hydantoin compounds, urea compounds and hydrazide compounds is sometimes simply referred to as "nitrogen-containing compound (C)".

[0041] The polyacetal resin composition of this embodiment may be a composition containing only polyacetal resin (A), formaldehyde scavenger (B) and nitrogen-containing compound (C), or it may also contain other components.

[0042] <Polyacetal Resin (A)>

[0043] Examples of the aforementioned polyacetal resin (A) include polyacetal homopolymers and polyacetal copolymers. Furthermore, the aforementioned polyacetal resin (A) can be used alone or in combination with two or more other resins.

[0044] As a polyacetal homopolymer, there are no particular limitations. For example, a polyacetal homopolymer that essentially contains only oxymethylene units can be obtained by polymerizing formaldehyde or its trimer (trioxymethylene), tetramer (tetraoxymethylene), and other cyclic oligomers of formaldehyde individually.

[0045] There are no particular limitations on what constitutes a polyacetal copolymer. Examples include: polyacetal copolymers obtained by copolymerizing formaldehyde or its trimer (trioxymethylene), tetramer (tetraoxymethylene), and other cyclic oligomers of formaldehyde with comonomers; and polyacetal copolymers synthesized using macromolecular initiators, macromolecular chain transfer agents, and macromolecular terminators.

[0046] Examples of primary structures for the aforementioned polyacetal resin (A) include those with chain, cyclic, and branched structures. Examples of branched structures include grafted structures, ladder structures, star structures, dendritic structures, and three-dimensional network structures. Furthermore, these branched structures can be synthesized using multifunctional comonomers, multifunctional chain transfer agents, and macromonomers.

[0047] The monomer sequences of the aforementioned polyacetal copolymers can be categorized as random, gradient, and block sequences.

[0048] When measured according to ISO 1133, the MFR of the above-mentioned polyacetal resin (A) is preferably 1 g / 10 min to 50 g / 10 min, more preferably 1 g / 10 min to 10 g / 10 min, and even more preferably 1 g / 10 min to 5 g / 10 min. By adjusting the MFR of the polyacetal resin (A) to the above range, the formaldehyde release under dry conditions can be further suppressed.

[0049] When determining the molecular weight and molecular weight distribution based on polymethyl methacrylate according to ISO 16014, the peak molecular weight of the above-mentioned polyacetal resin (A) is preferably 8 × 10⁻⁶. 4 The above is preferred, and more preferably is 10×10. 4 The above is preferred, with 15×10 being more ideal. 4 The above describes how adjusting the peak molecular weight of polyacetal resin (A) to the above range can further suppress formaldehyde release under dry conditions.

[0050] Furthermore, when the molecular weight and molecular weight distribution were determined according to ISO 16014 based on polymethyl methacrylate, the molecular weight relative to 100% by mass of the above-mentioned polyacetal resin (A) was 5 × 10⁻⁶. 4 The above components are preferably 70% by mass or more, and more preferably 85% by mass or more. This is achieved by using polyacetal resin (A) with a molecular weight of 5 × 10⁻⁶. 4 Adjusting the above components to the specified range can further suppress formaldehyde release under dry conditions.

[0051] There are no particular limitations on the manufacturing method of the aforementioned polyacetal resin (A), and it can be manufactured using known polymerization methods. Examples of such polymerization methods include bulk polymerization and solution slurry polymerization; both batch and continuous polymerization methods are possible. For bulk polymerization, self-cleaning mixers such as co-kneaders and twin-screw continuous extruders can be used. For solution slurry polymerization, reaction tanks with stirring mechanisms can be used.

[0052] As the polymerization catalyst for the aforementioned polyacetal resin (A), anionic polymerization catalysts and cationic polymerization catalysts can be used. Examples of anionic polymerization catalysts include: metallic sodium, Salts, etc. Examples of catalysts for cationic polymerization include Lewis acids and protic acids.

[0053] The aforementioned polyacetal resin (A) is characterized by its tendency to decompose easily after polymerization while remaining in its original state; therefore, it is used after end stabilization. Examples of end stabilization methods include: thermal decomposition to remove unstable ends in the molten state, and methods that alter the end structure by reacting with other compounds.

[0054] Relative to 100% by mass of the polyacetal resin composition of this embodiment, the mass ratio of the above-mentioned polyacetal resin (A) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. Alternatively, it can be 95% by mass or less, 99% by mass or less, or even less than 100% by mass.

[0055] The formaldehyde release of the polyacetal resin composition of this embodiment in a humid environment is preferably less than 3 μg per 1g of resin product, and more preferably less than 1.5 μg.

[0056] It should be noted that the formaldehyde emission level can be determined using the method described in the examples below.

[0057] The formaldehyde release of the polyacetal resin composition of this embodiment under dry conditions is preferably less than 0.2 μg per 1g of resin product, and more preferably less than 0.1 μg.

[0058] It should be noted that the formaldehyde emission level can be determined using the method described in the examples below.

[0059] Formaldehyde scavenger (B)

[0060] Formaldehyde scavenger (B) contains compound (b1).

[0061] Compound (b1) is a compound having a structure represented by the following formula (1).

[0062]

[0063] The above R 1 ~R 3 Each is independently selected from any one of the substituent groups consisting of hydrogen, alkyl, alkoxy, and alkylthio groups. The above R 1 R 2 and R 3 One or more of the above-mentioned R are preferably substituents having 10 or fewer carbon atoms. 1 R 2 and R 3 Further preferred substituents are those with 10 or fewer carbon atoms.

[0064] Examples of alkyl groups include methyl, ethyl, and other alkyl groups having 1 to 10 carbon atoms (preferably alkyl groups having 1 to 5 carbon atoms, and more preferably alkyl groups having 1 to 2 carbon atoms). These alkyl groups can be straight-chain or branched.

[0065] Examples of alkoxy groups include structures formed by bonding an alkyl group having 1 to 10 carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms) with an oxygen atom.

[0066] Examples of alkylthio groups include structures formed by bonding alkyl groups with 1 to 10 carbon atoms (preferably alkyl groups with 1 to 5 carbon atoms) to sulfur atoms.

[0067] From the perspective of suppressing the formation of mold deposits (MD), the above-mentioned R 1 ~R 3 The number of carbon atoms is preferably 10 or less, more preferably 5 or less.

[0068] The above R 4 It is selected from any one of the substituent groups consisting of hydrogen, hydroxyl, alkyl, alkoxy, and alkylthio.

[0069] Examples of alkyl groups include methyl, ethyl, and other alkyl groups having 1 to 10 carbon atoms (preferably alkyl groups having 1 to 5 carbon atoms, and more preferably alkyl groups having 1 to 2 carbon atoms). These alkyl groups can be straight-chain or branched.

[0070] Examples of alkoxy groups include structures formed by bonding an alkyl group having 1 to 10 carbon atoms (preferably an alkyl group having 1 to 5 carbon atoms) with an oxygen atom.

[0071] Examples of alkylthio groups include structures formed by bonding alkyl groups with 1 to 10 carbon atoms (preferably alkyl groups with 1 to 5 carbon atoms) to sulfur atoms.

[0072] As mentioned above, R1 and R 2 From the perspective of further suppressing formaldehyde release under dry conditions, hydrogen atoms are preferred.

[0073] As mentioned above, R 3 From the viewpoint of further suppressing formaldehyde release under dry conditions, hydrogen atoms or alkyl groups are preferred, and more preferably alkyl groups with 3 or fewer carbon atoms.

[0074] As mentioned above, R 4 From the viewpoint of further suppressing formaldehyde release under dry conditions, alkyl or alkoxy compounds are preferred.

[0075] The above structure can have R within the structure. 3 and R 4 A ring structure formed by interconnecting groups. As R 3 and R 4 The forms in which they are linked together via linking groups can be exemplified by, for example: R 3 and R 4 The hydrogen atoms in the linker are respectively replaced by the two ends of the linking group. This linking group can have a structure containing an alkylene group or containing an ether or thioether group between the alkylene groups. Alternatively, the linking group can be combined with R... 3 and R 4 The linking group has a structure containing oxygen or sulfur atoms. That is, the linking group can be a divalent group selected from the group consisting of alkylene, ether, and thioether groups, or it can be a divalent group formed by linking together one or more divalent groups selected from alkylene, ether, and thioether groups. Examples of such linking groups include: alkylene, ether, thioether, alkyleneoxy, alkylenethio, alkylene ether alkylene, alkylene thioether alkylene, oxoalkyleneoxy, thioalkylenethio, oxoalkylenethio, etc. From the viewpoint of further suppressing formaldehyde release under dry conditions, alkylene and alkyleneoxy groups are preferred.

[0076] In formula (1), the bond represented by the wavy line indicates a double bond that can be either cis or trans relative to the nitrogen atom. That is, in the above structure, the carbonyl carbon directly connected to the carbon double bond in the structure can be either cis or trans relative to the nitrogen atom. Alternatively, it can also be used in the form of a mixture of these structural isomers.

[0077] Examples of the above-mentioned compounds (b1) include: 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, methyl 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, methyl 3-amino-2-butenoic acid, ethyl 3-amino-2-butenoic acid, 3- Compounds whose structures do not form ring structures, such as n-propyl amino-2-butenoic acid, isopropyl amino-2-butenoic acid, tetradecyl amino-2-butenoic acid, hexadecyl amino-2-butenoic acid, octadecyl amino-2-butenoic acid, S-methyl amino-2-thiobutenoic acid, S-ethyl amino-2-thiobutenoic acid, methyl amino-2-pentenoic acid, methyl amino-2-hexenoic acid, methyl amino-4-methyl-2-pentenoic acid, and methyl 3-(dimethylamino)-2-butenoic acid.

[0078] Compounds with cyclic structures formed by the above structures, 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-dihydro-2H-pyran-2-one, and 4-amino-5,6-dihydro-2H-thiaran-2-one;

[0079] Compounds having multiple of the above structures, such as 1,2-ethylene glycol bis(3-amino-2-butenoate), 1,3-propanediol bis(3-amino-2-butenoate), 1,4-butanediol bis(3-amino-2-butenoate), 1,3-propanediol bis(3-amino-2-butenoate), and 2,9-diamino-2,8-decadien-4,7-dione.

[0080] From the viewpoint that it can further suppress the release of formaldehyde under dry conditions, the above compound (b1) is preferably methyl 3-amino-2-butenoate, 1,4-butanediol bis(3-amino-2-butenoate), or 3-amino-2-cyclohexene-1-one.

[0081] From the viewpoint of being able to suppress the formation of mold deposits (MD), the above-mentioned compound (b1) is preferably a compound having a plurality of the above-mentioned structures, more preferably 1,4-butanediol bis(3-amino-2-butenoate).

[0082] The content of the formaldehyde scavenger (B) relative to 100 parts by weight of polyacetal resin (A) is preferably in the range of 0.01 parts by weight or more, more preferably 0.03 parts by weight or more. By keeping the content of the formaldehyde scavenger (B) within the above range, it is possible to obtain a molded sheet with reduced formaldehyde release under dry conditions.

[0083] The content of the formaldehyde scavenger (B) relative to 100 parts by weight of polyacetal resin (A) is preferably in the range of 0.3 parts by weight or less, more preferably 0.1 parts by weight or less, and even more preferably 0.07 parts by weight or less. By keeping the content of formaldehyde scavenger (B) within the above range, the formation of formaldehyde scavenger (MD) during molding and processing can be suppressed.

[0084] In addition to compound (b1), the formaldehyde scavenger (B) mentioned above may contain other ingredients within a range that does not impede the effect of reducing formaldehyde release.

[0085] The content of the above-mentioned compound (b1) is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more, and may also be 100% by mass, relative to 100% by mass of the above-mentioned formaldehyde scavenger (B).

[0086] The content of the above-mentioned compound (b1) is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, relative to 100 parts by mass of polyacetal resin (A). By keeping the content of compound (b1) within the above range, it is possible to obtain a molded sheet with reduced formaldehyde release under drying conditions.

[0087] The content of the above-mentioned compound (b1) relative to 100 parts by weight of polyacetal resin (A) is preferably in the range of 0.3 parts by weight or less, more preferably 0.1 parts by weight or less, and even more preferably 0.07 parts by weight or less. By keeping the content of compound (b1) within the above range, the formation of MD during molding and processing can be suppressed.

[0088] <Nitrogen-containing compounds (C)>

[0089] The nitrogen-containing compound (C) included in this embodiment is selected from the group consisting of hydantoin compounds, urea compounds, and hydrazide compounds. They may be used individually or in combination of two or more.

[0090] In this embodiment, from the viewpoint of reducing formaldehyde release in humid environments, hydantoin compounds, ethylidene urea, or aliphatic hydrazides are preferred as nitrogen-containing compounds (C), and ethylidene urea, sebacic acid dihydrazides, or adipic acid dihydrazides are more preferred.

[0091] <Hydroxyurea compounds>

[0092] Examples of the aforementioned hydantoin compounds include, but are not limited to, hydantoin, 5,5-dimethylhydantoin, and 5,5-diphenylhydantoin.

[0093] <Urea compounds>

[0094] Examples of the aforementioned urea compounds include, but are not limited to, allantoin and ethylurea. In particular, from the viewpoint of suppressing formaldehyde release in humid environments, allantoin or ethylurea is preferred, and ethylurea is more preferred.

[0095] <Acylhydrazide compounds>

[0096] As the aforementioned acylhydrazine compound, an acylhydrazine compound synthesized by reacting a carboxylic acid (including aromatic and alicyclic compounds) with hydrazine can be used. It should be noted that in the case of compounds having multiple carboxyl groups, any compound obtained by reacting at least one carboxyl group with hydrazine is acceptable. Examples of carboxylic acid mono(di)hydrazides synthesized using carboxylic acids include: carbamate, oxalate mono(di)hydrazide, malonate mono(di)hydrazide, succinate mono(di)hydrazide, glutarate mono(di)hydrazide, adipic acid mono(di)hydrazide, sebacic acid mono(di)hydrazide, lauryl hydrazide, malic acid diacylhydrazide, tartrate diacylhydrazide, propionyl hydrazide, lauroyl hydrazide, stearyl hydrazide, phthalic acid diacylhydrazide, isophthalic acid diacylhydrazide, terephthalic acid diacylhydrazide, 2,6-naphthalenedicarboxylic acid diacylhydrazide, p-hydroxybenzoyl hydrazide, 1,4-cyclohexanedicarboxylic acid diacylhydrazide, acetyl hydrazide, acrylamide diacylhydrazide, maleic acid diacylhydrazide, fumarate diacylhydrazide, benzoyl hydrazide, nicotinic acid diacylhydrazide, isonicotinic acid diacylhydrazide, isobutyryl hydrazide, and oleyl hydrazide. Among these hydrazide compounds, sebacic acid diacylhydrazide and adipic acid diacylhydrazide are particularly preferred.

[0097] It should be noted that "mono(di) hydrazide" means that one or both of the two carboxyl groups form an hydrazide.

[0098] The content of nitrogen-containing compound (C) relative to 100 parts by weight of polyacetal resin (A) is preferably in the range of 0.01 parts by weight or more, more preferably 0.03 parts by weight or more. By keeping the content of nitrogen-containing compound (C) within the above range, it is possible to obtain a molded sheet with reduced formaldehyde release in humid environments.

[0099] The content of nitrogen-containing compound (C) relative to 100 parts by weight of polyacetal resin (A) is preferably in the range of 0.3 parts by weight or less, more preferably 0.1 parts by weight or less, and even more preferably 0.07 parts by weight or less. By keeping the content of nitrogen-containing compound (C) within the above range, the formation of mold fouling during molding can be suppressed.

[0100] From the viewpoint of highly suppressing formaldehyde release in both humid and dry environments, the content of formaldehyde scavenger (B) 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, relative to the total content of the formaldehyde scavenger (B) and nitrogen-containing compound (C) of 100% by mass.

[0101] <Other Additives (D)>

[0102] In the polyacetal resin composition of this embodiment, within a range that does not impair the properties of the polyacetal resin (A), for example, preferably, relative to 100 parts by weight of the polyacetal resin composition, it may contain 2 parts by weight or less of a known additive (other additive (D) other than formaldehyde scavenger (B) and nitrogen-containing compound (C)). Examples of other additives (D) include: antioxidants, heat stabilizers, formic acid scavengers, weather stabilizers, mold release agents, lubricants, conductive agents, thermoplastic resins, thermoplastic elastomers, pigments and dyes, inorganic fillers and organic fillers, etc.

[0103] The other additives (D) mentioned above can be used alone or in combination of two or more.

[0104] Hindered phenolic antioxidants are preferred as the antioxidants mentioned above.

[0105] Examples of hindered phenolic antioxidants include, but are not limited to, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl 3-(3-methyl-5-tert-butyl-4-hydroxyphenyl)propionate, tetradecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,4-butanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Among them, triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] and pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are preferred.

[0106] The antioxidants mentioned above can be used alone or in combination of two or more.

[0107] Examples of heat stabilizers mentioned above include polyamides and polyacrylamides. These heat stabilizers can be used alone or in combination of two or more.

[0108] Examples of the aforementioned polyamides include, for example, cyclic amide polymers such as polyamide 4, polyamide 6, polyamide 10, and polyamide 12, and their copolymers; condensation polymers of dicarboxylic acids and diamines, but not limited to these. Examples of the aforementioned dicarboxylic acids include, for example, aliphatic dicarboxylic acids such as adipic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid. Examples of the aforementioned diamines include, for example, hexamethylenediamine.

[0109] The aforementioned polyacrylamide can have a polyamide 3 structure generated through a hydrogen transfer reaction, which is a side reaction during polymerization. The aforementioned polyacrylamide can also have an intramolecular and / or intermolecular crosslinking structure by utilizing an imide structure generated through a deamination reaction, which is a side reaction during polymerization. Furthermore, the aforementioned polyacrylamide can be a copolymer of acrylamide and its derivatives. Examples of derivatives of acrylamide include, for example, N-alkylacrylamide. Additionally, the aforementioned polyacrylamide can be a copolymer with a crosslinking structure obtained by copolymerization with a comonomer having multiple acrylamide groups. Examples of comonomers having multiple acrylamide groups include, for example, methylenebisacrylamide.

[0110] Examples of formic acid scavengers include, but are not limited to, hydroxides of alkali metals or alkaline earth metals, inorganic acid salts, carboxylates, or alkoxides. Examples include hydroxides of sodium, potassium, magnesium, calcium, or barium; carbonates, phosphates, silicates, borates, carboxylates, and layered double hydroxides of the aforementioned metals.

[0111] The formic acid scavengers mentioned above can be used alone or in combination of two or more.

[0112] The carboxylic acid that is the above-mentioned carboxylate is preferably a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms.

[0113] Examples of the aforementioned carboxylate salts include, but are not limited to, calcium dimyristicate, calcium distearate, calcium distearate, calcium (myristic acid-palmitic acid), calcium (myristic acid-stearic acid), calcium (palmitic acid-stearic acid), and calcium 12-hydroxystearate. Among these, calcium dimyristicate, calcium distearate, and calcium 12-hydroxystearate are preferred.

[0114] Examples of weather stabilizers mentioned above include, but are not limited to, benzotriazole compounds, oxaloyl aniline compounds, and hindered amine light stabilizers.

[0115] The above-mentioned weather stabilizers can be used alone or in combination of two or more.

[0116] Examples of the aforementioned benzotriazole compounds include, but are not limited to, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]benzotriazole, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, 2-(2-hydroxy-3,5-diisopentylphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis-(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, and 2-(2-hydroxy-4-octoxyphenyl)benzotriazole.

[0117] Examples of the above-mentioned oxaloylaniline compounds include, but are not limited to, 2-ethoxy-2'-ethyloxaloylaniline, 2-ethoxy-5-tert-butyl-2'-ethyloxaloylaniline, and 2-ethoxy-3'-dodecyloxaloylaniline.

[0118] Examples of hindered amine light stabilizers include: 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(phenylacetoxy)-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, and 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, di(2,2,6,6-tetramethyl-4-piperidinyl) carbonate, di(2,2,6,6-tetramethyl-4-piperidinyl) oxalate, di(2,2,6,6-tetramethyl-4-piperidinyl) malonate, di(1,2,6,6,6-pentamethyl-4-piperidinyl) sebacate, di(N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate Di(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, di(2,2,6,6-tetramethyl-4-piperidinyl) adipate, di(2,2,6,6-tetramethyl-4-piperidinyl) terephthalate, 1,2-bis(2,6,6-tetramethyl-4-piperidinyloxy)ethane, α,α'-bis(2,2,6,6-tetramethyl-4-piperidinyloxy)p-xylene, di(2,2,6,6-tetramethyl-4-piperidinyl) toluene-2,4-dicarbamate, di(2,2,6,6-tetramethyl-4-piperidinyl) hexamethylene-1,6-dicarbamate, phenyl-1,3,5-tricarboxylic acid Tris(2,2,6,6-tetramethyl-4-piperidinyl) ester, tris(2,2,6,6-tetramethyl-4-piperidinyl) ester of phenyl-1,3,4-tricarboxylic acid, condensates of 1-[2-{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy}butyl]-4-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidin, condensates of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and β,β,β',β'-tetramethyl-3,9-[2,4,8,10-tetraoxaziro(5,5)undecane]diethanol, etc., but not limited thereto.

[0119] As the aforementioned weather stabilizers, the preferred choices are condensates of 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]benzotriazole, 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-tert-pentylphenyl)benzotriazole, di(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, di(N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, di(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 1,2,3,4-butanetetracarboxylic acid with 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.

[0120] As the aforementioned release agent and lubricant, alcohols, fatty acids and their fatty acid esters, olefin compounds with an average degree of polymerization of 10 to 500, and organosilicones are preferred, but not limited thereto.

[0121] The above-mentioned release agent and lubricant can be used alone or in combination of two or more.

[0122] Examples of conductive agents mentioned above include, but are not limited to, conductive carbon black, metal powder, or fibers.

[0123] The aforementioned conductive agents can be used alone or in combination of two or more.

[0124] Examples of the aforementioned thermoplastic resins include, but are not limited to, polyolefin resins, acrylic resins, styrene resins, polycarbonate resins, and uncured epoxy resins.

[0125] The above-mentioned thermoplastic resins can be used alone or in combination of two or more.

[0126] Examples of thermoplastic elastomers mentioned above include polyurethane elastomers, polyester elastomers, polystyrene elastomers, and polyamide elastomers, but are not limited to these.

[0127] The above-mentioned thermoplastic elastomers can be used alone or in combination of two or more.

[0128] Examples of pigments and dyes mentioned above include, but are not limited to, inorganic pigments, organic pigments and dyes, metallic pigments, and fluorescent pigments.

[0129] The pigments and dyes mentioned above can be used alone or in combination of two or more.

[0130] The aforementioned inorganic pigments refer to inorganic pigments commonly used for coloring resins, such as zinc sulfide, titanium dioxide, barium sulfate, titanium yellow, cobalt blue, calcined pigments, carbonates, phosphates, acetates, carbon black, acetylene black, etc., but are not limited to these.

[0131] Examples of organic pigments and dyes mentioned above include: condensed azo, quinones, monoazo, diazo, polyazo, anthraquinones, heterocyclic, violet ketones, quinacridones, thioindigo, perylene, and diazonium. Pigments and dyes such as azine and phthalocyanine, but not limited to these.

[0132] It should be noted that the addition ratio of the above pigments and dyes varies greatly depending on the hue, and therefore is difficult to specify precisely. Generally speaking, they are used in the range of 0.05 parts by weight to 5 parts by weight relative to 100 parts by weight of polyacetal resin.

[0133] As the aforementioned inorganic filler, fibrous, granular, plate-like, and hollow fillers can be used, but are not limited thereto.

[0134] The aforementioned inorganic fillers can be used alone or in combination of two or more.

[0135] Examples of fibrous fillers include, but are not limited to, glass fibers, carbon fibers, silicone fibers, silica-alumina fibers, zirconium oxide fibers, boron nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, and inorganic fibers such as stainless steel, aluminum, titanium, copper, and brass. Additionally, examples include short-fiber potassium titanate whiskers and zinc oxide whiskers.

[0136] Examples of the aforementioned granular fillers include: talc, carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, magnesium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, wollastonite, and other silicates; metal oxides such as iron oxide, titanium oxide, and aluminum oxide; metal sulfates such as calcium sulfate and barium sulfate; carbonates such as magnesium carbonate and dolomite; as well as silicon carbide, silicon nitride, boron nitride, and various metal powders, but are not limited to these.

[0137] Examples of plate-shaped fillers include, but are not limited to, mica, glass flakes, and various metal foils.

[0138] Examples of hollow fillers include, but are not limited to, glass hollow microspheres, silica hollow microspheres, white sand hollow microspheres, and metal hollow microspheres.

[0139] Examples of organic fillers mentioned above include, but are not limited to, aromatic polyamide resins, fluorinated resins, acrylic resins, and other high-melting-point organic fibrous fillers.

[0140] The above-mentioned organic fillers can be used alone or in combination of two or more.

[0141] The aforementioned inorganic and organic fillers can also be substances that have undergone surface treatment using a surface treatment agent. Such surface treatment can adjust the smoothness and mechanical properties of the molded surface.

[0142] There are no particular restrictions on the surface treatment agent used; any previously known surface treatment agent may be used.

[0143] As surface treatment agents, various coupling agents such as silanes, titanates, aluminum-containing agents, and zirconium-containing agents, as well as surfactants such as resin acids, organic carboxylic acids, and salts of organic carboxylic acids can be used, but are not limited to these. Specifically, examples include N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, isopropyl tristearoyl titanate, aluminum diisopropoxyethyl acetoacetate, n-butyl zirconate, etc., but are not limited to these.

[0144] 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.

[0145] Properties of Polyacetal Resin Compositions

[0146] The polyacetal resin composition of this embodiment preferably has low measured values ​​for both formaldehyde release under humid and dry conditions. That is, the smaller the product of the measured values ​​for formaldehyde release under humid and dry conditions, the better it can suppress formaldehyde release under all conditions, which is preferred. The formaldehyde release under humid and dry conditions can be measured using the methods described in the examples below.

[0147] From a molding processability point of view, the less mold fouling (MD) generated in the polyacetal resin composition of this embodiment, the better. The amount of mold fouling (MD) generated can be measured by the method described in the examples below.

[0148] <Method for manufacturing polyacetal resin composition>

[0149] The polyacetal resin composition of this embodiment can be manufactured, for example, by a known melt-blending method.

[0150] For example, the polyacetal resin (A) and the compound can be mixed using a mixer such as a Henschel mixer and fed into a single-screw or twin-screw melt mixing device (extruder) for melt mixing. Alternatively, the polyacetal resin can be supplied upstream of a single-screw or twin-screw extruder and molten, and then the compound can be supplied downstream for melt mixing.

[0151] The polyacetal resin composition of this embodiment can be used as a raw material for molded articles. It can be molded into any shape and used, for example, for injection molded articles, fibers, nonwoven fabrics, sheets, films, and profiled extrusions.

[0152] <Uses of Molded Articles of Polyacetal Resin Compositions>

[0153] The molded articles of the polyacetal resin composition of this embodiment exhibit excellent quality stability and can therefore be used as molded articles for various applications. For example, they can be used for mechanism parts such as gears, cams, sliders, rods, shafts, bearings, and guides; resin parts injection molded onto a matrix or resin parts molded as inserts (chassis, tray, side panel parts); parts for printers or copiers; parts for digital cameras or digital video devices; parts for music, imaging, or information devices; parts for communication devices; parts for electrical devices; and parts for electronic devices.

[0154] In addition, the molded articles of the polyacetal resin composition of this embodiment are suitable for use as automotive parts such as fuel peripheral parts, door peripheral parts, seat belt peripheral parts, combination switch parts, and switches.

[0155] Furthermore, the molded articles of the polyacetal resin composition of this embodiment have significantly reduced formaldehyde release in both humid and dry environments, and are therefore suitable for use as transport containers for precision equipment such as semiconductors and electronic equipment components.

[0156] Example

[0157] The present invention will now be described in more detail based on embodiments, but the present invention is not limited to these embodiments.

[0158] The raw material components used in the examples and comparative examples are as follows.

[0159] <Polyacetal Resin (A)>

[0160] The polyacetal homopolymer obtained by polymerizing formaldehyde (MFR = 2.0 g / 10 min, peak molecular weight 16.7 × 10⁻⁶) was used. 4 It contains 89% by mass of a molecular weight of 5 × 10⁻⁶. 4(The above components). It should be noted that the MFR value was determined according to ISO 1133-1 using a MELT INDEXER manufactured by Toyo Seiki Co., Ltd., under conditions of a barrel temperature of 190°C and a load of 2.16 kg. Molecular weight and molecular weight distribution were determined according to ISO 16014 using an HLC-8320GPC manufactured by Tosoh Co., Ltd., under conditions of a column temperature of 40°C, as molecular weight and molecular weight distribution converted to polymethyl methacrylate.

[0161] Formaldehyde scavenger (B)

[0162] B-1: Methyl 3-amino-2-butenoate (Tokyo Kasei)

[0163] B-2: 1,4-Butanediol bis(3-amino-2-butenoate) (Tokyo Kasei)

[0164] B-3: 3-Amino-2-cyclohexen-1-one (Tokyo Kasei)

[0165] <Nitrogen-containing compounds (C)>

[0166] C-1: Ethylene urea (Tokyo Kasei)

[0167] C-2: Adipic acid dihydrazide (Tokyo Kasei)

[0168] C-3: Sebacic acid dihydrazide (Tokyo Kasei)

[0169] C-4: Hydantoin (Tokyo Kasei)

[0170] C-5: Allantoin (Tokyo Kasei)

[0171] <(D) Other Additives>

[0172] D-1: Triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] (Matsuhara Corporation)

[0173] D-2: Acrylamide copolymer (Asahi Kasei Fine Chemicals)

[0174] The measurement and evaluation methods are described below.

[0175] <(1) Formaldehyde release under humid conditions (VDA275 value)>

[0176] Using an injection molding machine (IS-100GN manufactured by Toshiba Machine Co., Ltd.), test pieces (100mm × 40mm × 3mm flat plates) were molded from the polyacetal resin compositions obtained in the examples and comparative examples under the conditions of mold temperature 77°C, barrel temperature 200°C, injection pressure 35MPa, injection time 15 seconds, and cooling time 20 seconds.

[0177] The formaldehyde release from the test piece was determined according to the method described in German automotive industry standard VDA275. Specifically, the test piece was suspended and sealed in a 1L polyethylene bottle containing 50mL of distilled water, without contact with the water. It 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 then reacted with acetylacetone in the presence of ammonium ions. The reaction product was used as the reactant, and the absorption peak at 412nm was measured using a UV spectrometer to determine the formaldehyde release. It should be noted that the formaldehyde release is expressed as the amount of formaldehyde relative to 1g of polyacetal resin (μg / g). A lower value indicates more suppressed formaldehyde release, which is preferable.

[0178] <(2) Formaldehyde release under dry conditions (sampling bag method value)>

[0179] Using an injection molding machine (IS-100GN manufactured by Toshiba Machine Co., Ltd.), test pieces (100mm × 40mm × 3mm flat plates) were molded from the polyacetal resin compositions obtained in the examples and comparative examples under the conditions of mold temperature 77°C, barrel temperature 200°C, injection pressure 35MPa, injection time 15 seconds, and cooling time 20 seconds.

[0180] Two molded test pieces were sealed in a 10L polyvinyl fluoride sampling bag and degassed. 4L of nitrogen was added, and the bag was heated at 65°C for 2 hours. Then, 3L of nitrogen was extracted from the sampling bag at a rate of 0.5ml / min, allowing the generated formaldehyde to be adsorbed into a DNPH (2,4-dinitrophenylhydrazine) collection tube (Sep-Pak DNPH-Silica: manufactured by Waters).

[0181] Then, the reaction product of DNPH and formaldehyde was extracted from the DNPH collection tube using acetonitrile. The amount of formaldehyde produced was determined using high-performance liquid chromatography (HPLC) and a calibration curve method using a standard reference of the reaction product of DNPH and formaldehyde, expressed as the amount of formaldehyde relative to 1g of polyacetal resin (μg / g). The smaller this value, the more formaldehyde release is suppressed, which is preferred.

[0182] It should be noted that in Comparative Example 1, the formaldehyde release exceeded the capacity of the DNPH trapping tube, therefore the measured value is not shown.

[0183] <(3) Evaluation of MD>

[0184] Using an injection molding machine (Si30-V manufactured by Toyo Machinery Metal Co., Ltd.), the operation of producing molded sheets from the polyacetal resin compositions obtained in the examples and comparative examples was repeatedly performed under the conditions of mold temperature 43°C, barrel temperature 200°C, injection time 20 seconds, and cooling time 20 seconds.

[0185] The adhesion of mold fouling (MD) in the mold cavity was observed after the 1000th injection from the start of molding, and the fouling (MD) properties were evaluated according to the following criteria.

[0186] ○ (Excellent): No MD adhesion is observed inside the mold cavity.

[0187] △ (Good): A small amount of MD adhesion was observed inside the mold cavity.

[0188] × (Defect): A large amount of film-like MD adhesion was observed inside the mold cavity.

[0189] [Examples 1-13, Comparative Examples 1-9]

[0190] The mixtures shown in Table 1 were mixed and fed into a twin-screw extruder (TEM manufactured by Shibaura Machinery Co., Ltd.). The mixtures were melt-blended at a screw speed of 100 rpm and a barrel temperature of 210°C, followed by granulation. The resulting granules were dried in a hot air dryer at 80°C for 3 hours, and then shaped and evaluated using the method described above.

[0191] The evaluation results are summarized in Table 1.

[0192] [Table 1]

[0193]

Claims

1. A polyacetal resin composition, wherein, The polyacetal resin composition contains: Polyacetal resin (A) Formaldehyde scavenger (B) comprising a compound (b1) having a structure represented by the following formula (1), and Nitrogen-containing compounds (C). The nitrogen-containing compound (C) is at least one selected from the group consisting of hydantoin compounds, ureido compounds, and hydrazide compounds. In equation (1), R 1 R 2 and R 3 Each can be independently selected from any one of the substituent groups consisting of hydrogen, alkyl, alkoxy, and alkylthio groups. R 4 It is selected from any one of the substituent groups consisting of hydrogen, hydroxyl, alkyl, alkoxy, and alkylthio groups. R 3 and R 4 They can be interconnected via linking groups to form a ring structure, as represented by equation (1). The linking group is a divalent group selected from the group consisting of alkylene, ether, and thioether groups, or a divalent group formed by linking together one or more of these divalent groups. The bond represented by the wavy line indicates a double bond, and it can be either cis or trans relative to the nitrogen atom.

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 adipate dihydrazide.

3. The polyacetal resin composition according to claim 1 or 2, wherein, The R 1 R 2 and R 3 All of them are substituents with 10 or fewer carbon atoms.

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-butenoate) and 3-amino-2-cyclohexen-1-one.

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