JP2019099654A - Polyoxymethylene resin molded article - Google Patents

Abstract

To provide a polyoxymethylene resin molded article and a polyoxymethylene resin composition each of which has less odor, less generation amount of debris even when continuously molded, and has high resistibility against grease.SOLUTION: The polyoxymethylene resin molded article is provided which includes 100 pts.mass of a polyoxymethylene resin and 0.1 to 0.5 pts.mass of an amide compound having a melting point of 300°C or higher, and in which amount of acetic acid extracted in 150 g of water coexisting under environment at 80°C for 15 days from one or more molded article having total surface area corresponding to surface area of 60 mm by 60 mm by 3 mm rectangular solid is 80 mass.ppm or less based on total mass of the molded article. The polyoxymethylene resin composition is also provide which includes 100 pts. mass of the polyoxymethylene resin and 0.1 to 0.5 pts. mass of the amide compound having a melting point of 300°C or higher, and in which amount of acetic acid extracted in 150 g of water coexisting under environment at 80°C for 15 days from one molded article molded to rectangular solid with 60 mm by 60 mm by 3 mm is 80 mass. ppm or less based on total mass of the molded article.SELECTED DRAWING: None

Description

  The present invention relates to a polyoxymethylene resin molded article.

  Since polyoxymethylene resin is a crystalline resin and is excellent in rigidity, strength, toughness, slidability, and creepability, conventionally, materials for mechanical parts such as automobile parts, electric / electronic parts and industrial parts, etc. It is widely used.

In the case of a polyoxymethylene resin molded article formed by molding a polyoxymethylene resin composition, in recent years, the demand for downsizing, thinning and refinement has been increasing, and a molding method in which a heat history is more likely to be applied than before. And molding conditions are increasing.
For example, molding with a pin gate mold and high cycle molding may be mentioned, and furthermore, the molding method is carried out using a high viscosity polyoxymethylene resin to achieve miniaturization, thinning and refinement of the molded product. In the above-described forming method, the polyoxymethylene resin receives a higher heat history than a general forming method by increasing the shear rate and shortening the plasticizing time to increase screw rotation and forming temperature. Also in other common molding methods, when molding defects such as flow marks, weld lines, jetting, etc. occur, the resin temperature is often raised by raising it, which also has a high heat history. It becomes such a factor. Furthermore, when a hot runner is used for the mold, the resin temperature may rise due to partial retention of the resin, the resin may be decomposed, or the additive may be carbonized to become foreign matter.

Then, the polyoxymethylene resin composition which improved the stability of polyoxymethylene resin is proposed.
For example, a polyoxymethylene resin composition (see, for example, Patent Document 1) and a pigment which can effectively suppress the thermal decomposition of the polyoxymethylene resin and the generation of foreign matter even if molding is performed continuously for a long time. Polyoxymethylene resin composition which can suppress the generation of formaldehyde even if it is added (see, for example, Patent Document 2), a polyoxymethylene resin composition which is excellent in thermal stability, less staying coloring, and excellent in productivity. (For example, see Patent Document 3) has been proposed.

JP, 2013-155285, A JP 2011-52128 A JP, 2009-256425, A

  However, the polyoxymethylene resin compositions disclosed in Patent Documents 1 to 3 still have room for improvement in the reduction of the odor of the molded product of polyoxymethylene resin, the reduction of the amount of foreign matter generation, and the improvement of the grease resistance. is there.

  Therefore, the problem to be solved by the present invention is to produce a molded article of polyoxymethylene resin molded article having little odor, little generation of foreign matter even when continuous molding is performed, and high grease resistance. It is an object of the present invention to provide a polyoxymethylene resin composition that can

  MEANS TO SOLVE THE PROBLEM As a result of repeating earnest research in order to solve the said subject, the present inventors discovered that the polyoxymethylene resin molded product which has a specific characteristic could solve the said subject, and completed this invention.

That is, the present invention is as follows.
[1]
A polyoxymethylene resin molded article comprising 100 parts by mass of a polyoxymethylene resin and 0.1 to 0.5 parts by mass of an amide compound having a melting point of 300 ° C. or higher,
Acetic acid extracted from 150 g of water coexisting in an environment of 80 ° C. for 15 days from one or more of the polyoxymethylene resin molded articles having a total surface area corresponding to the surface area of one rectangular solid of 60 mm × 60 mm × 3 mm A polyoxymethylene resin molded article, wherein the amount is 80 mass ppm or less based on the total mass of the polyoxymethylene resin molded article.
[2]
Total organic carbon extracted from 150 g of water coexisting in an environment of 15 days at 80 ° C. from one or more of the polyoxymethylene resin molded articles having a total surface area corresponding to a surface area of a rectangular solid of 60 mm × 60 mm × 3 mm The polyoxymethylene resin molded article according to the above [1], wherein the amount of is 450 ppm by mass or less based on the total mass of the polyoxymethylene resin molded article.
[3]
The polyoxymethylene resin molded article according to the above [1] or [2], wherein the amide compound is 0.2 to 0.5 parts by mass.
[4]
The polyoxymethylene resin molded article according to any one of the above [1] to [3], wherein the evaluation result evaluated by the VDA 270 test of the German Automobile Manufacturers Association is 4.0 or less.
[5]
The polyoxymethylene resin molded article according to any one of the above [1] to [4], which is used for a cosmetic container, an instrument panel peripheral part or an air conditioner peripheral part in automobile interior, or a gear application in contact with grease.

[6]
A polyoxymethylene resin composition comprising 100 parts by mass of a polyoxymethylene resin and 0.1 to 0.5 parts by mass of an amide compound having a melting point of 300 ° C. or higher,
Of acetic acid extracted from one single polyoxymethylene resin molded article into 150 g of water coexisting at 80 ° C. for 15 days when molded into a 60 mm × 60 mm × 3 mm rectangular polyoxymethylene resin molded article Polyoxymethylene resin composition characterized in that the amount is 80 mass ppm or less with respect to the mass of the polyoxymethylene resin molded article.
[7]
When molded into a rectangular solid polyoxymethylene resin molded article of 60 mm × 60 mm × 3 mm, the whole product is extracted from one of the molded polyoxymethylene resin articles into 150 g of water coexisting under an environment of 15 days at 80 ° C. The polyoxymethylene resin composition according to the above-mentioned [6], wherein the amount of body carbon is 450 mass ppm or less based on the total mass of the polyoxymethylene resin molded article.
[8]
The polyoxymethylene resin composition as described in said [6] or [7] whose said amide compound is 0.2-0.5 mass part.
[9]
When molded into a 120 mm × 80 mm × 3 mm rectangular polyoxymethylene resin molded article, an evaluation result of evaluating one of the polyoxymethylene resin molded articles by the VDA 270 test of the German Automotive Industry Association is 4.0 or less The polyoxymethylene resin composition according to any one of the above [6] to [8].

  According to the present invention, it is possible to obtain a polyoxymethylene resin molded article having a high degree of grease property and a composition thereof, which has a low odor and a small amount of foreign matter generation even when continuous molding is performed.

It is an image figure of extraction experiments of acetic acid and total organic carbon used in the example.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as the present embodiment) will be described in detail. In addition, this invention is not limited to the following embodiment, It can variously deform and implement within the range of the summary.

[Polyoxymethylene resin molded article (P)]
The polyoxymethylene resin molded article (P) of the present embodiment contains the polyoxymethylene resin (A) and the amide compound (B), and may optionally contain the additive (s) as an optional component. Good.
The polyoxymethylene resin molded article (P) of the present embodiment is formed by molding a polyoxymethylene resin composition (p).

[Polyoxymethylene resin composition (p)]
The polyoxymethylene resin composition (p) formed into the polyoxymethylene resin molded product (P) of the present embodiment contains a polyoxymethylene resin (A) and an amide compound (B), and as necessary, Additive (s) is included as an optional component.
Each component will be described in detail below.

[[Polyoxymethylene resin (A)]]
As polyoxymethylene resin (A), polyoxymethylene homopolymer (a-1) and polyoxymethylene copolymer (a-2) are mentioned, for example.
As polyoxymethylene resin (A), polyoxymethylene homopolymer (a-1) may be used alone or in combination with polyoxymethylene copolymer (a-2). Although not particularly limited, the polyoxymethylene resin (A) preferably contains 50% by mass or more of the polyoxymethylene homopolymer (a-1), more preferably 70% by mass or more, from the viewpoint of rigidity and strength. More preferably, it contains 80% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more of the polyoxymethylene homopolymer (a-1).

<Polyoxymethylene Homopolymer (a-1)>
The polyoxymethylene homopolymer (a-1) is a polymer having only oxymethylene units in its main chain.
Both ends or one end of the polyoxymethylene homopolymer (a-1) may be blocked by an ester group or an ether group.
The polyoxymethylene homopolymer (a-1) may be used alone or in combination of two or more different in weight average molecular weight, number average molecular weight, molecular weight distribution, and / or type of terminal capping group, etc. It is also good.

  The polyoxymethylene homopolymer (a-1) can be produced by the following (1) polymerization step and (2) terminal stabilization step using the later-described monomer, chain transfer agent, and polymerization catalyst as raw materials.

(1) Polymerization step Polyoxymethylene homopolymer (a-1) is produced by a known slurry polymerization method (for example, the method described in JP-B-47-6420 and JP-B-47-10059), It can be obtained as a crude polyoxymethylene homopolymer whose end is not stabilized.

1) Monomer As a monomer used for manufacture of polyoxymethylene homopolymer (a-1), formaldehyde etc. are mentioned, for example.
In order to continuously obtain a stable molecular weight polyoxymethylene homopolymer (a-1), it is preferable to use a purified formaldehyde gas which is purified and has a low impurity concentration. Examples of methods for purifying formaldehyde include known methods (for example, methods described in Japanese Patent Publication No. 5-32374 and Japanese Patent Publication No. 2001-521916).
When formaldehyde gas is used as the monomer, it is preferable that the monomer containing as little as possible impurities having a polymerization termination function or a chain transfer function during the polymerization reaction, such as water, methanol, formic acid or the like. As these impurities are less, unexpected chain transfer reaction can be avoided, and a polyoxymethylene homopolymer (a-1) of the target molecular weight can be obtained. Among them, the content of the impurity that induces a hydroxyl group in the polymer terminal group is preferably 80 mass ppm or less, and more preferably 50 mass ppm or less with respect to the total amount of monomers.

2) Chain transfer agent Although it does not specifically limit as a chain transfer agent used for manufacture of a polyoxymethylene homopolymer (a-1), Generally alcohol and an acid anhydride can be used.
As the chain transfer agent, it is preferable to use water, methanol, formic acid, acetic acid and the like that do not contain as much as possible impurities having a polymerization termination action or chain transfer action during the polymerization reaction. As a method of obtaining a chain transfer agent with few impurities, for example, a widely used chain transfer agent whose available water content exceeds a specified amount is bubbled with dry nitrogen, and the impurities are removed by an adsorbent such as activated carbon or zeolite. And purification methods.
The chain transfer agent may be used alone or in combination of two or more.

3) Polymerization catalyst Although it does not specifically limit as a polymerization catalyst used for manufacture of polyoxymethylene homopolymer (a-1), For example, an onium salt type polymerization catalyst etc. are mentioned.
As an onium salt type | system | group polymerization catalyst, the compound etc. which are represented by following formula (1) are mentioned, for example.
^{[R 1 R 2 R 3 R} 4 M] + X - ··· (1)
(In formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent an alkyl group, M represents an element having a lone electron pair, and X represents a nucleophilic group. R ¹ , R 2 ² , R ³ and R ⁴ may be the same or different.)
Examples of the onium salt-based polymerization catalyst include quaternary ammonium salt-based compounds and quaternary phosphonium salt-based compounds. Among them, tetramethyl ammonium bromide, dimethyl distearyl ammonium acetate, tetraethyl phosphonium iodide, tributyl Ethyl phosphonium iodide is preferred.

4) Reactor The reactor used for producing the polyoxymethylene homopolymer (a-1) is not particularly limited. For example, a batch-type reactor with a stirrer, a continuous co-kneader, a twin-screw continuous extrusion A kneader, a twin-screw paddle type continuous mixer, etc. may be mentioned.
It is preferable that the outer periphery of the cylinder of the reactor has a structure capable of heating or cooling the reaction mixture.

(2) End Stabilizing Step After the polymerization step (1), the end of the crude polyoxymethylene homopolymer obtained is blocked with an ether group and / or an ester group to stabilize the end.

Examples of methods for end stabilization by capping the ends of the crude polyoxymethylene homopolymer with an ether group include known methods (for example, the method described in JP-B-63-452).
Although it does not specifically limit as an etherifying agent in the case of capping by ether group, For example, an ortho ester etc. are mentioned.
The ortho ester includes, for example, an ortho ester of an aliphatic acid or an aromatic acid and an aliphatic alcohol, a cycloaliphatic alcohol or an aromatic alcohol, etc. Specifically, methyl or ethyl orthoformate, Examples include methyl or ethyl orthoacetate and methyl or ethyl orthobenzoate, and ortho carbonates such as ethyl ortho carbonate.
The etherifying agent may be used alone or in combination of two or more.
Etherification reaction is carried out using 1 mass of etherifying agent catalyst of Lewis acid type such as medium strength organic acid such as p-toluenesulfonic acid, acetic acid and hydrobromic acid, medium strength mineral acid such as dimethyl and diethyl sulfate. You may introduce and carry out 0.001-0.02 mass parts with respect to a part.
The etherification reaction may be carried out in the presence of a predetermined solvent. The solvent used for the etherification reaction is not particularly limited. For example, low boiling point aliphatics such as pentane, hexane, cyclohexane and benzene; alicyclic groups and aromatic hydrocarbons; methylene chloride, chloroform and carbon tetrachloride Organic solvents such as halogenated lower aliphatic compounds can be mentioned.

As a method for end-capping the end of the crude polyoxymethylene homopolymer obtained in the polymerization step with an ester group, for example, a large amount of acid anhydride described in U.S. Pat. No. 3,459,709 And the method of carrying out in the slurry state, and the method of carrying out in the gas phase using the gas of an acid anhydride described in US Pat. No. 3,172,736.
Although it does not specifically limit as an esterification agent in the case of blocking by ester group, For example, an organic acid anhydride etc. are mentioned.
As an organic acid anhydride, the organic acid anhydride etc. which are represented by following formula (2) etc. are mentioned, for example.
R ⁵ COOCOR ⁶ (2)
(In formula (2), R ⁵ and R ⁶ each independently represent an alkyl group or a phenyl group. R ⁵ and R ⁶ may be the same or different.)
Examples of the organic acid anhydride include propionic acid anhydride, benzoic acid anhydride, acetic acid anhydride, acetic acid anhydride, succinic acid anhydride, maleic acid anhydride, glutaric acid anhydride, phthalic acid anhydride and the like, with preference given to acetic acid anhydride.
The esterifying agent may be used alone or in combination of two or more.
In the method of performing ester group blocking in the gas phase, it is preferable to perform terminal blocking after removing the onium salt-based polymerization catalyst by the method described in JP-A-11-92542. When the onium salt polymerization catalyst in polyoxymethylene is removed, the decomposition reaction of the polyoxymethylene homopolymer (a-1) derived from the onium salt polymerization catalyst can be avoided when the terminal is blocked, and the terminal is stabilized. While being able to improve the polymer yield in reaction, the coloring of polyoxymethylene homopolymer (a-1) can be suppressed.

It is preferable that the terminal hydroxyl group concentration be reduced to 5 × 10 ⁻⁷ mol / g or less by blocking the end of the polyoxymethylene homopolymer (a-1) with an ether group and / or an ester group. When the concentration of terminal hydroxyl groups is 5 × 10 ^-7 mol / g or less, the thermal stability is excellent, and the quality of the original polyoxymethylene homopolymer (a-1) can be maintained, which is preferable. The concentration of the terminal hydroxyl group is more preferably 0.5 × 10 ⁻⁷ mol / g or less, still more preferably 0.3 × 10 ⁻⁷ mol / g or less.

<Polyoxymethylene Copolymer (a-2)>
The polyoxymethylene copolymer (a-2) is a copolymer containing oxymethylene units and comonomer units and having oxymethylene units in the main chain.
The comonomer unit in the polyoxymethylene copolymer (a-2) may be any unit copolymerizable with the oxymethylene unit, and is not limited to the following, but is, for example, an oxyalkylene unit having 2 or more carbon atoms Is preferred.
The polyoxymethylene copolymer (a-2) preferably contains 0.3 mol or more, more preferably 0.4 mol or more, and preferably 0.5 mol or more of comonomer units per 100 mol of oxymethylene units. The content is more preferably 0.6 mol or more, still more preferably 1.2 mol or more. The polyoxymethylene copolymer (a-2) preferably contains 3.0 mol or less, more preferably 2.0 mol or less, and still more preferably 1.5 mol or less of comonomer units.
By setting the content ratio of the comonomer unit to 100 mol of the oxymethylene unit in the above preferable range, it is possible to improve the dimensional accuracy and the quality while improving the appearance and texture of the polyoxymethylene resin molded product (P).

The polyoxymethylene copolymer (a-2) is a base catalyst of a thermally unstable terminal [-(OCH ₂ ) n -OH group] contained in a crude polyoxymethylene copolymer obtained by a known polymerization method. It may be one which has been decomposed and removed by a method such as, for example, and converted to a stable end such as [-OCH ₂ CH ₂ -OH group].
The molecular weight (weight-average molecular weight, number-average molecular weight), molecular weight distribution, branched structure, etc. of the polyoxymethylene copolymer (a-2) are not particularly limited, and are suitable for use of the desired polyoxyethylene resin molded article (P), etc. It can be selected accordingly.
As the polyoxymethylene copolymer (a-2), one type may be used alone, or two or more types may be used in combination.

[Amide compound (B)]
The molded product of polyoxymethylene resin of the present embodiment contains an amide compound (B) having a melting point of 300 ° C. or higher. By containing the amide compound (B), formaldehyde generated from the polyoxymethylene resin (A) by decomposition or the like reacts with the amide compound to inhibit the oxidation of formaldehyde to formic acid or the like, thereby causing polyoxy acids caused by formic acid or the like. The decomposition of the methylene resin can be suppressed. In addition, when the melting point of the amide compound is 300 ° C. or more, the generation of foreign matter can be effectively reduced.

The amide compound (B) having a melting point of 300 ° C. or higher includes, for example, nylon 6T-66, nylon 6T-6I, nylon 6T-6I-66, nylon 6T-2M-5T, nylon 9T, nylon 9T-2M-8T, etc. Polyamide resin etc. are mentioned.
In addition, as an amide compound (B) whose melting | fusing point is 300 degreeC or more, the copolymer of acrylamide and its derivative (s), acrylamide and its derivative, and another vinyl monomer etc. are mentioned, for example.
In addition, specific examples of the amide compound (B) having a melting point of 300 ° C. or higher include, but are not limited to, polycarboxylic acid amides such as isophthalic acid diamide, anthranylamide and the like.
Among these, copolymers of acrylamide and its derivatives with other vinyl monomers are most preferred.

  The addition amount of the amide compound (B) is 0.1 to 0.5 parts by mass, preferably 0.1 to 0.4 parts by mass, with respect to 100 parts by mass of polyoxymethylene. .3 parts by weight is more preferred. When the addition amount of the amide compound (B) is in the above range, the polyoxymethylene resin molded product has less odor, and even if continuous molding is performed, the generation amount of foreign matter in the molded product is small and the grease resistance is high. A polyoxymethylene resin composition can be obtained.

[Additive (s)]
Examples of the additive (s) include an antioxidant, a stabilizer, a weathering (light) agent, a lubricant and a release agent, a crystal nucleating agent, an inorganic and organic filler, a conductive agent and an antistatic agent, and an appearance improvement Agents (pigments, dyes, etc.) and the like.
The additive (s) preferably contains an antioxidant and a heat stabilizer. The antioxidant is preferably a hindered phenolic antioxidant, and the heat stabilizer is preferably one containing formaldehyde reactive nitrogen.
These additives (s) may be used alone or in combination of two or more.

<Antioxidant>
As the antioxidant, hindered phenol-based antioxidants are suitably used.
Examples of hindered phenolic antioxidants include, but are not limited to, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, for example. n-Octadecyl-3- (3′-methyl-5′-t-butyl-4′-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ′, 5′-di-t-butyl-4′- Hydroxyphenyl) -propionate, 1,6-hexanediol-bis- [3- (3,5-di-t-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 tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane and the like. Preferably, triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] and pentaerythritol tetrakis [methylene-3- (3 ', 5'-di-t] -Butyl-4'-hydroxyphenyl) propionate] methane.
These antioxidants may be used singly or in combination of two or more.

Stabilizers
As a stabilizer, a heat stabilizer is suitably used.
Examples of heat stabilizers include, but are not limited to, amino-substituted triazine compounds, adducts of amino-substituted triazine compounds with formaldehyde, condensates of amino-substituted triazine compounds with formaldehyde, urea, urea derivatives, hydrazine derivatives And imidazole compounds and imide compounds.

Specific examples of amino-substituted triazine compounds include, but are not limited to, 2,4-diamino-sym-triazine, 2,4,6-triamino-sym-triazine, N-butylmelamine, N-phenyl Melamine, N, N-diphenylmelamine, N, N-diallylmelamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), acetoguanamine (2,4-diamino-6-methyl-sym-triazine) 2,4-diamino-6-butyl-sym-triazine and the like.
Specific examples of the adduct of amino-substituted triazine compound and formaldehyde include, but are not limited to, N-methylolmelamine, N, N′-dimethylolmelamine, N, N ′, N ′ ′-trimethylolmelamine Etc.
Specific examples of the condensation product of the amino-substituted triazine compound and formaldehyde include, but are not limited to, melamine-formaldehyde condensates and the like.
Examples of urea derivatives include, but are not limited to, N-substituted ureas, urea condensates, ethylene ureas, hydantoin compounds, ureide compounds and the like. Specific examples of the N-substituted urea include methyl urea substituted with a substituent such as an alkyl group, alkylene bis urea, and aryl substituted urea. Specific examples of the urea condensate include condensates of urea and formaldehyde. Specific examples of hydantoin compounds include hydantoin, 5,5-dimethylhydantoin, 5,5-diphenylhydantoin and the like. As a specific example of the ureide compound, allantoin and the like can be mentioned.

Hydrazide compounds can be mentioned as examples of hydrazine derivatives. Specific examples of the hydrazide compound include dicarboxylic acid dihydrazide, and more specifically, although not limited thereto, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid Dihydrazide, speric acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, phthalic acid dihydrazide, 2,6-naphthalenedicarbohydrazide and the like.
Specific examples of the imidazole compound include, but are not limited to, imidazole, 1-methylimidazole, 2-methylimidazole, 1,2-dimethylimidazole and the like.
Specific examples of the imide compound include, but are not limited to, succinimide, glutarimide, phthalimide and the like.

Other stabilizers are not limited to the following, but include, for example, hydroxides, inorganic acid salts, carboxylates or alkoxides of alkali metals or alkaline earth metals, and specifically, And hydroxides such as sodium, potassium, magnesium, calcium or barium, carbonates, phosphates, silicates, borates, carboxylates of the above metals, and layered double hydroxides.
The carboxylic acid of the carboxylic acid salt is preferably a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms, and these carboxylic acids may be substituted by a hydroxyl group. Specific examples of the saturated or unsaturated aliphatic carboxylic acid salt include calcium dimyristate, calcium dipalmitate, calcium distearate, calcium (myristate-palmitate), calcium (myristate-stearate), (palmitate) Calcium stearate and the like, preferably calcium dipalmitate and calcium distearate;
Examples of layered double hydroxides include hydrotalcites represented by the following formula (4).
_{^{[(M 2+) 1-X (}} M 3+) X (OH) 2 ] ^{X + _{[(A n-) x / n ·}} mH 2 O ] ^X - ··· (4)
(In the formula (4), M ²⁺ is a divalent metal, M ³⁺ is a trivalent metal, A ^n-n-valent (n represents an anion of an integer of 1 or more), X is, 0 <X ≦ 0 In the range of .33, m represents a positive number)
In formula (4), examples of M ²⁺ include Mg ²⁺ , Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ^{2+ and the} like, and examples of M ^{3+ the, Al 3+, Fe 3+, Cr} 3+, Co 3+, etc. in ^3+, and examples of a ^{n- is, OH -, F -, Cl} -, Br -, NO 3- And CO ₃ ^2- , SO ₄ ^2- , Fe (CN) ₆ ^3- , CH ₃ COO ⁻ , oxalate ion, salicylate ion and the like. As an example of A ^n- , OH ^- and CO ₃ ^2- are preferable.
Specific examples of the hydrotalcites include, but are not limited to, natural hydrotalcites represented by Mg _0.75 Al _0.25 (OH) ₂ (CO ₃ ) _0.125 · 0.5 H ₂ O, Mg _4.5 Al Synthetic hydrotalcites represented by ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O, Mg _4.3 Al ₂ (OH) _12.6 CO ₃ etc. may be mentioned.
These stabilizers may be used alone or in combination of two or more.

<Weather (light) agent>
Examples of the weathering (light) agent include, but are not limited to, benzotriazole-based ultraviolet absorbers, boric acid anilide-based ultraviolet absorbers and hindered amine-based light stabilizers.
Specific examples of the benzotriazole-based ultraviolet absorber include, but are not limited to, 2- (2'-hydroxy-5'-methyl-phenyl) benzotriazole, 2- (2'-hydroxy-3 ') 5'-di-t-butyl-phenyl) benzotriazole, 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- [2 Examples include '-hydroxy-3', 5'-bis- (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole and the like.
Specific examples of oxalic acid alinide-based UV absorbers include, but are not limited to, 2-ethoxy-2'-ethyl oxalamic acid bis anilide, 2-ethoxy-5-t-butyl-2'- Ethyl oxalic acid bis anilide, 2-ethoxy-3'- dodecyl oxalic acid bis anilide etc. are mentioned. Preferably, 2- [2′-hydroxy-3 ′, 5′-bis- (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di And -t-butyl-phenyl) benzotriazole and the like.

Specific examples of the hindered amine light stabilizer include, but are not limited to, N, N ′, N ′ ′, N ′ ′ ′-tetrakis- (4,6-bis- (butyl- (N−) Methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, dibutylamine · 1,3,5-triazine N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine Polycondensates of poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetra] Methyl-4-piperidyl) imino} hexamethylene {(2,2,6 , 6-Tetramethyl-4-piperidyl) imino}], a condensate of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol, bis (2,2,2 decanedioate) Reaction product of 6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester with 1,1-dimethylethyl hydroperoxide and octane, bis (1,2,2,6,6-pentamethyl-4 -Piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate, methyl-1,2,2,6,6-pentamethyl-4-piperidyl sebacate, Bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl- -A condensation product of piperidinol with β, β, β ', β'-tetramethyl-3, 9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethanol, etc. may be mentioned. Is bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, bis- (N-methyl-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 1,2,3 2,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ', β'-tetramethyl-3,9- [2,4,8,10- It is a condensate with tetraoxaspiro (5,5) undecane] diethanol.
These weathering (light) agents may be used alone or in combination of two or more.

<Lubricant and mold release agent>
Examples of lubricants and mold release agents include, but are not limited to, alcohols, fatty acids and fatty acid esters thereof, polyoxyalkylene glycols, olefin compounds having an average degree of polymerization of 10 to 500, silicones, etc. It can be mentioned.
These lubricants and release agents may be used alone or in combination of two or more.

<Crystal nucleating agent>
Examples of crystal nucleating agents include, but are not limited to, for example, talc, silica, quartz powder, glass powder, calcium silicate, aluminum silicate, aluminum silicate, kaolin, pyrophyllite, clay, diatomaceous earth, wollastonite, etc. Salts, metal oxides such as iron oxide or titanium oxide or alumina, metal sulfates such as calcium sulfate or barium sulfate, calcium carbonate or magnesium carbonate or dolomite carbonates, other silicon carbide, boron nitride, boron nitride, various metals These include finely divided solids of various crystal nucleating inorganic substances usually known in polyoxymethylene resins, such as powders. Among these, as the nucleating agent, boron nitride and talc are preferable.
In the crystal nucleation inorganic substance, a known surface treatment agent may be used to improve the affinity and dispersibility with the resin. The surface treatment agent is not limited to the following. For example, silane coupling agents such as aminosilane and epoxysilane, titanate coupling agents, and further fatty acids (saturated fatty acids, unsaturated fatty acids), alicyclics Examples include carboxylic acids and resin acids and metal soaps. The amount of the surface treatment agent added is preferably 3% by mass or less, more preferably 2% by mass or less, based on the crystal nucleation inorganic substance.
The crystal nucleating agent may be used alone or in combination of two or more.

<Inorganic / organic filler>
Examples of inorganic fillers include, but are not limited to, metal powders (aluminum, stainless steel, nickel, silver, etc.), oxides (silicon oxide, iron oxide, alumina, titanium oxide, zinc oxide, etc.) , Hydroxides (aluminum hydroxide, magnesium hydroxide, calcium hydroxide etc.), silicates (talc, mica, clay, bentonite etc.), carbonates (calcium carbonate, magnesium carbonate, hydrotalcite etc.), carbon-based substances (Carbon black, graphite, carbon fiber, etc.), sulfate, boron nitride, silicon nitride, etc. may be mentioned.
Examples of the organic filler include, but are not limited to, natural products (linter, wood, rice husk, silk, leather, etc.) and synthetics (aramid, Teflon (registered trademark), viscose, etc.) Can be mentioned.
Among them, it is preferable to select from among inorganic and organic fillers that can be added to conventional polyoxymethylene resins. That is, since addition of a strongly acidic / alkaline filler to polyoxymethylene resin may lower the stability, it is possible to use conventional inorganic / organic fillers added to polyoxymethylene resin and proven as commercial products. It is preferable to be selected.
The shape of the inorganic / organic filler may be any of powder, scale, plate, needle, sphere, fiber, tetrapod, etc., and is not particularly limited.
The inorganic and organic fillers may use known surface treatment agents in order to improve the affinity to the resin. The surface treatment agent is not limited to the following. For example, silane coupling agents such as aminosilane and epoxysilane, titanate coupling agents, and further fatty acids (saturated fatty acids, unsaturated fatty acids), alicyclics Examples thereof include carboxylic acids and resin acids, metal soaps, and resins. 3 mass% or less is preferable with respect to the inorganic and organic filler, and, as for the addition amount of a surface treatment agent, 2 mass% or less is more preferable.
The inorganic and organic fillers may be used alone or in combination of two or more.

<Conductive agent / Antistatic agent>
Examples of the conductive agent include, but are not limited to, conductive carbon black, carbon nanotubes or nanofibers or nanoparticles, metal powder or fibers, and the like.
Examples of antistatic agents include, but are not limited to, aliphatic polyethers (but excluding compounds in which the terminal is a fatty acid ester), aliphatic polyethers in which the terminal is a fatty acid ester, and fatty acids, for example. And fatty acid esters of polyhydric alcohols having free hydroxyl groups obtained from polyhydric alcohols, boric acid esters of glycerin monofatty acid esters, ethylene oxide adducts of amine compounds, basic carbonates or anion exchangers thereof as a substrate The antistatic agent etc. which included the alkylene polyol or the alkali metal salt melt | dissolution polyalkylene polyol are mentioned.
The conductive agent and the antistatic agent may be used alone or in combination of two or more.

<Appearance improving agent>
Examples of the appearance improver include, but are not limited to, inorganic pigments and organic pigments, metallic pigments, and fluorescent pigments.
Inorganic pigments refer to those generally used for coloring resins, and are not limited to, for example, zinc sulfide, titanium oxide, barium sulfate, titanium yellow, cobalt blue, fuel Synthetic pigments, carbonates, phosphates, acetates and carbon blacks, acetylene blacks, lamp blacks and the like.
As organic pigments, for example, condensed urazo type, inone type, flotacyanin type, monoazo type, diazo type, polyazo type, anthraquinone type, heterocyclic type, pennon type, quinacridone type, thioindico type, berylene type, dioxazine type, And pigments such as phthalocyanines.
The appearance improving agent may be used alone or in combination of two or more.

The content of the additive (s) in the polyoxymethylene resin composition (p) is preferably 100 parts by mass or less and 50 parts by mass or less with respect to 100 parts by mass of the polyoxymethylene resin (A). It is more preferable that it is 25 mass parts or less. When two or more additives (s) are used in combination, the total content of the additive (s) is preferably in the above range.
By making content of an additive (s) into a preferable range, the polyoxymethylene resin molded article (P) comprised using polyoxymethylene resin composition (p) stays in a molding machine for a long time Also, the appearance of the molded article is better, and even when continuous molding is performed, the amount of foreign matter generated in the molded article is smaller, and it tends to have higher grease resistance.

[Method of producing polyoxymethylene resin composition (p)]
The method for producing the polyoxymethylene resin composition (p) for producing the polyoxymethylene resin molded product (P) of the present embodiment is not particularly limited, but the production of the polyoxymethylene resin composition (p) is described below. The method will be described by way of example.
The polyoxymethylene resin composition (p) can be obtained by mixing the polyoxymethylene resin (A), the amide compound (B), and the additive (s) as an optional component, and melt-kneading it. it can.
At the time of granulation of the polyoxymethylene resin (A), the resin composition (p) may be obtained by adding the amide compound (B) and an additive (s) as an optional component and melt kneading. In addition, after granulating the polyoxymethylene resin (A), after mixing the amide compound (B) and the additive (s) as an optional component using a Henschel mixer, tumbler or V-shaped blender, kneader, roll mill The polyoxymethylene resin composition (p) may be obtained by melt-kneading using a single-screw extruder, a twin-screw extruder or a multi-screw extruder.
The end-stabilized polyoxymethylene resin (A) is preferably dried and melt-kneaded while adding an amide compound (B) and a stabilizer as an additive (s) to perform granulation.
When melt-kneading, in order to maintain the quality and the working environment, it is preferable to replace the atmosphere with an inert gas or to perform degassing by single-stage and multi-stage venting. The temperature for melt-kneading is preferably from the melting point of polyoxymethylene resin (A) to 250 ° C. or less, and may be 20 to 50 ° C. higher than the melting point of polyoxymethylene resin (A).

In order to enhance the dispersibility of the amide compound (B) and the additive (s) in the polyoxymethylene resin (A), part or all of the polyoxymethylene resin (A) to be mixed prior to mixing is pulverized, After mixing with the amide compound (B) and the additive (s), it may be melt-kneaded. In this case, a spreading agent may be used to further enhance the dispersibility.
The spreading agent is not particularly limited, and examples thereof include aliphatic hydrocarbons and aromatic hydrocarbons, modified products thereof, fatty acid esters of polyols and the like.
The spreading agents may be used alone or in combination of two or more, such as aliphatic hydrocarbons, aromatic hydrocarbons, and mixtures of modified products thereof.
The amide compound (B) and the additive (s) may be mixed with the polyoxymethylene resin (A) in several portions.

  The polyoxymethylene resin molded article whose quantity of acetic acid extracted with 150g of water made to coexist in the environment left to stand at 80 ° C for 15 days so that it may mention below 80 mass ppm or less to the mass of a polyoxymethylene resin molded article In the production of the polyoxymethylene resin composition (p), removal of formaldehyde remaining during polymerization and acetic acid derived from acetic anhydride added in the terminal stabilization step, Control from the viewpoint of suppression of decomposition of A) is important. For that purpose, specifically, the terminal-stabilized polyoxymethylene resin (A) is dried in a powder form having a large surface area at 80 ° C. for 3 hours or more, or left at room temperature for 24 hours or more after drying. And removing acetic acid and formaldehyde as much as possible; in the production of the resin composition (p), the formaldehyde which is generated upon decomposition into pellets upon melt-kneading into pellets by lowering the number of rotations during extrusion, etc. And / or adding an appropriate additive (s) in an appropriate amount; and the like. In addition, there are methods such as discharging acetic acid and formaldehyde from an extrusion vent by repeatedly performing extrusion 2 to 5 times under a loose operating condition in which the number of rotations is reduced so as not to cause decomposition.

[Characteristics of Polyoxymethylene Resin Composition (p)]
The melt flow rate (MFR) of the polyoxymethylene resin composition (p) is preferably 0.6 to 60 g / 10 min, more preferably 0.9 to 15 g / 10 min, and 2.0 It is more preferable that it is -5 g / 10 minutes.
By setting the MFR of the resin composition (p) to the above-mentioned preferable range, productivity and grease resistance at the time of molding are improved, and a high-quality polyoxymethylene resin molded article (P) with few foreign matter tends to be obtained. is there.
In this embodiment, the melt flow rate of the polyoxymethylene resin composition (p) is measured in accordance with ISO 1133 (condition D · temperature 190 ° C.).
In the measurement of the melt flow rate of the polyoxymethylene resin composition (p), the polyoxymethylene resin molded article (P) may be used as it is as a measurement sample, or the polyoxymethylene resin molded article by crushing or cutting A part may be collected from P) and used as a measurement sample.

[Method for producing polyoxymethylene resin molded article (P)]
The polyoxymethylene resin molded article (P) of the present embodiment is obtained by molding the polyoxymethylene resin composition (p). It does not specifically limit as method to manufacture polyoxymethylene resin molded article (P), A well-known shaping | molding method is mentioned.
As the molding method, for example, extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decoration molding, multicolor molding, gas assist injection molding, foam injection molding, low pressure molding, super thin wall injection molding ( Ultra high speed injection molding), in-mold composite (insert molding, outsert molding), press molding, vacuum press molding and the like.
As molding conditions, it is preferable to perform molding at a resin temperature of the resin composition (p) at molding of 10 ° C. or more from the melting point of the resin composition (p) and 10 ° C. of the decomposition temperature. Further, the mold temperature at the time of molding is preferably 30 ° C. or more and 120 ° C. or less, more preferably 60 ° C. or more and 90 ° C. or less.

[Characteristics of Polyoxymethylene Resin Molded Article (P)]
The polyoxymethylene resin molded article (P) of the present embodiment is obtained from one or more of the polyoxymethylene resin molded articles having a total surface area corresponding to the surface area of one 60 mm × 60 mm × 3 mm rectangular solid for 15 days at 80 ° C. The amount of acetic acid extracted in 150 g of water allowed to coexist in the left environment is 80 mass ppm or less based on the total mass of the polyoxymethylene resin molded product (P). The amount of acetic acid is preferably 65 mass ppm or less, more preferably 50 mass ppm or less.
When the amount of the acetic acid is in the above range, it is possible to obtain a molded article of polyoxymethylene resin having less odor and less foreign matter. Although the reason is not clear, it is guessed as follows. The foreign substance in the polyoxymethylene resin molded product (P) is an amide compound of which the acid remaining in the polyoxymethylene resin (A) during the melt-kneading of the production of the polyoxymethylene resin composition (p) is a stabilizer. It is considered that the melted amide compound below the melting point and the melted amide compound adhere to the screw and stay and ash. Since the acid remaining in the polyoxymethylene resin (A) is carried into the polyoxymethylene resin molded article (P) and extracted into water coexisted in the above-mentioned environment, the amount of acid extracted into water May be an indicator of the amount of acid remaining in the polyoxymethylene resin (A). And, the amount of acid remaining in the polyoxymethylene resin (A) is specified to such an extent that melting, retention and incineration of the amide compound can be suppressed if the amount of acetic acid extracted into water is below a specific range It is shown that the polyoxymethylene resin molded article (P) is less than the above-mentioned range, and has few foreign substances.

  In order to reduce the amount of acetic acid extracted into water, use a monomer with few impurities in the production of the polyoxymethylene resin (A) or thoroughly wash the produced polyoxymethylene resin (A) And / or reducing the substance which produces | generates acetic acid contained in polyoxymethylene resin composition (p), etc. by leaving time before granulation etc. is mentioned. Also, a substance that captures and neutralizes acetic acid may be added as an additive (s).

In addition, the polyoxymethylene resin molded article (P) of the present embodiment is obtained at 80 ° C. from one or more of the polyoxymethylene resin molded articles having a total surface area corresponding to the surface area of one 60 mm × 60 mm × 3 mm rectangular solid. It is preferable that the amount of total organic carbon extracted in 150 g of water allowed to coexist in an environment left to stand for 15 days is 450 mass ppm or less based on the total mass of the polyoxymethylene resin molded product (P) The amount is preferably 350 mass ppm or less, and more preferably 300 mass ppm or less.
When the amount of the total organic carbon is in the above range, it is possible to obtain a molded article having a smaller amount of generated Holm at the time of retention in the molding machine and less foreign matter.
In order to reduce the amount of total organic carbon extracted into water, measures such as improvement of reaction rate and prevention of contamination may be made. Specifically, in the process of producing the polyoxymethylene resin composition (p), using the polyoxymethylene resin (A) sufficiently reacted, thermal damage is reduced, residual monomers, incorporated solvents, etc. The polyoxymethylene resin molded product (P (P)) by reducing the amount of impurities contained in the polyoxymethylene resin composition (p) and the contamination of impurities such as unnecessary low-boiling oil and water-soluble substances into the polyoxymethylene resin composition (p). Contamination of total organic carbon) can be reduced.

In the present embodiment, a test solution from which acetic acid and total organic carbon have been extracted is collected, for example, as follows.
In a closed container, put the polyoxymethylene resin molded product (P) together with a beaker containing 150 g of water, leave it in an oven at 80 ° C for 15 days, and then return to normal temperature to use the water in the beaker as the test solution . At this time, it is confirmed that the change in the amount of water in the beaker is 10% by mass or less when left for 15 days.
When changing over 10% by mass of 150g, it is assumed that the vapor phase part is large and the evaporation amount is large, and after leaving for 15 days, adjust the amount of water so that the remaining water is 150g Measure.
As water, it is preferable to use commercially available distilled water, and it is preferable to use an acetic acid concentration of 0.1 mg / L or less and total organic carbon 1 mg / L or less before measurement.
In addition, the atmosphere contained in the closed container is ordinary, that is, left in an oven at a temperature of 80 ° C. for 15 days without containing the molded product of polyoxymethylene resin, and the increment of acetic acid concentration contained in 150 g of remaining water is 0 .1 mg / L or less and an increment of total organic carbon concentration of 3 mg / L or less are used. A gas adjusted to 80 vol% nitrogen and 20 vol% oxygen may be used.
The size of the closed container may be appropriately set according to the size of the polyoxymethylene resin molded product.

The polyoxymethylene resin molded article to be measured is one or more polyoxymethylene resin molded articles having a total surface area corresponding to the surface area of one 60 mm × 60 mm × 3 mm rectangular solid.
Specifically, when the size of the polyoxymethylene resin molded product (P) to be evaluated is larger than 60 mm × 60 mm × 3 mm, the surface area is the same as one 60 mm × 60 mm × 3 mm rectangular solid. Let the thing which cut be a measurement sample.
When the size of the polyoxymethylene resin molded product (P) to be evaluated is 60 mm × 60 mm × 3 mm or less, using a plurality of the molded products, one rectangular solid having a total surface area of 60 mm × 60 mm × 3 mm is used. Let it be a measurement sample so that it becomes the same.

The test solution collected as described above is divided into one for determination of acetic acid and one for determination of total organic carbon and subjected to each analysis.
For quantification of acetic acid, generally known anion quantification methods can be used. For example, quantification is performed by analyzing water before and after the test using an ion chromatography apparatus (ICS-150 manufactured by Nippon Dynex Co., Ltd., IC 500 manufactured by Yokokawa Hewlett Packard Co., etc.).
For quantifying total organic carbon (TOC), generally known methods for quantifying organic carbon in water can be used. For example, quantification is performed by analyzing water before and after the test using a total organic carbon meter (TOC-VWS manufactured by Shimadzu Corporation, HT100 manufactured by Horiba Advanced Techno Corporation, etc.).

Moreover, as for the polyoxymethylene resin molded article (P) of this embodiment, it is preferable that the evaluation result evaluated by the VDA270 test of German Automotive Industry Association is 4.0 or less, and is 3.5 or less. Preferably, it is more preferably 3.0 or less.
If the evaluation result evaluated by the VDA 270 test is within the above range, the odor is sufficiently reduced to the extent that there is no concern about the human body or the environment in general applications and usage modes of the polyoxymethylene resin molded product It can be said that

The evaluation of the amount of acetic acid extracted into water, the amount of total organic carbon extracted into water, and the evaluation of the VDA 270 test, which are described above for molded articles of polyoxymethylene resin, are directed to evaluation of polyoxymethylene resin compositions. It is also good.
When the polyoxymethylene resin composition is to be evaluated for the amount of acetic acid and total organic carbon extracted in water, a rectangular solid of 60 mm × 60 mm × 3 mm according to the molding method and temperature conditions described above for the method for producing a molded article What was molded to the molded article of 1 may be used as a measurement sample.
Moreover, when making a polyoxymethylene resin composition into evaluation object of VDA270 test, according to the shaping | molding method and temperature condition as described in the Example mentioned later, what was shape | molded into 120 mm x 80 mm x 3 mm rectangular parallelepiped molded article It may be used as a measurement sample.

[Uses of polyoxymethylene resin molded product (P)]
The polyoxymethylene resin molded product (P) of the present embodiment has little odor and foreign matter, is excellent in grease resistance, and has high quality, so it can be used as a cosmetic container or an automobile, alone or in combination with metal parts. It can be suitably used for instrument panel peripheral parts and air conditioner peripheral parts in interiors, gear applications in contact with grease, electrical equipment parts, electronic equipment parts, and various other automotive and industrial applications.
In addition, the polyoxymethylene resin molded article (P) of the present embodiment is suitably used in containers, parts, etc., which are used in a high temperature and high humidity environment and / or in contact with grease among the above applications. Can.

  Hereinafter, the present invention will be described by way of examples and comparative examples, but the present embodiment is not limited to the following examples. The evaluation method in an Example and a comparative example is as follows.

[Amount of acetic acid extracted before and after high temperature and high humidity treatment of polyoxymethylene resin molded product]
As shown in the image of FIG. 1, the polyoxymethylene resin molded product is made to coexist with 150 g of distilled water (manufactured by SIGMA-ALDRICH) contained in a beaker in a 2 L polypropylene container, and sealed in a closed 80 ° C. gear oven. It was left for a day to carry out high temperature and high humidity treatment.
Ion chromatograph (Nihon Dionex Co., Ltd. ion chromatograph: ICS-1500, ion exchange column: IonPacAS1, column temperature: 30 ° C., eluent: 1 mM / L octane sulfonic acid, flow rate: 1 mL / min) It did. In this quantitative method, peaks are detected at about 10 minutes for acetic acid, 8 to 9 minutes for formic acid, and 7 to 8 minutes for lactic acid. The amount of acetic acid was measured by quantifying the peaks detected before and after the high temperature and high humidity treatment and the calibration curve. The amount of acetic acid in distilled water before the high temperature and high humidity treatment was 0.1 mg / L or less of the detection limit.

[Amount of total organic carbon extracted before and after high temperature and high humidity treatment of polyoxymethylene resin molded product]
As shown in the image of FIG. 1, the polyoxymethylene resin molded product is allowed to coexist with 150 g of distilled water (manufactured by SIGMA-ALDRICH) contained in a beaker in a 2 L polypropylene container for 15 days in a closed 80 ° C. gear oven It was left to stand and subjected to high temperature and high humidity treatment.
Total carbon (TC) and inorganic carbon (IC) were measured using a total organic carbon meter (total organic carbon meter manufactured by Shimadzu Corporation: TOC-V CSN), and quantification was made based on this difference. It was done to determine the amount of total organic carbon. The amount of total organic carbon in distilled water before the high temperature and high humidity treatment was 1 mg / L or less.

[Evaluation of VDA 270]
The cylinder temperature is set 30 ° C. higher than the melting point using a polyoxymethylene resin composition (p) and an injection molding machine (J110AD manufactured by Japan Steel Works, Ltd.), and the mold temperature is 80 ° C., and the cooling time is 30 As a second, a square polyoxymethylene molded product of 120 mm × 80 mm (3 mm thickness) was produced. Put two 120 mm x 80 mm (3 mm thick) square polyoxymethylene moldings in a 3 L glass jar, close the lid, heat at 80 ° C for 2 hours, open the lid and then 10 cm from the lid The nose came to the place, and it breathed in large, smelled smell, and evaluated according to the following evaluation criteria.
(Evaluation criteria)
1: No odor detectable 2: Perceptible but not unpleasant 3: Clearly perceived but not unpleasant 4: Discomfort 5: Very uncomfortable 6: Not acceptable Evaluation is performed by 5 people, and the evaluation value of 5 people After calculating the average value of, it evaluated according to the following evaluation criteria.
(Evaluation criteria)
○: 3 or less :: greater than 3 and 3.5 or less Δ: greater than 3.5 and 4.0 or less ×: greater than 4.0

[Evaluation of foreign matter count]
The cylinder temperature is set 30 ° C. higher than the melting point using a polyoxymethylene resin composition (p) and an injection molding machine (J110AD manufactured by Japan Steel Works, Ltd.), and the mold temperature is 80 ° C., and the cooling time is 30 As a second, 3000 pieces of 60 mm square (3 mm thick) square polyoxymethylene molded articles (P) were continuously produced. A total of 70 samples were taken for 10 sheets at the initial stage of molding and 10 sheets for every 500 shots, the number of foreign substances on the surface was counted, and the total number of foreign substances per all samples was evaluated according to the following evaluation criteria .
(Evaluation criteria)
○: 5 or less ◇: 5 to 20 △: 20 to 50 ×: 50 or more

[Evaluation of grease resistance]
The cylinder temperature is set 30 ° C. higher than the melting point using a polyoxymethylene resin composition (p) and an injection molding machine (J110AD manufactured by Japan Steel Works, Ltd.), and the mold temperature is 80 ° C., and the cooling time is 30 As a second, a tensile test piece (according to ISO 3167) was produced. After immersing the tensile test specimen in grease (Mappen AC-K manufactured by Kyodo Yushi Co., Ltd.) for 20 days at 110 ° C., tensile test (according to ISO 527) with a universal tester (Autograph AGS-X manufactured by Shimadzu Corporation) Was carried out at n = 5, and the obtained tensile elongation (%) was arithmetically averaged and evaluated according to the following evaluation criteria.
(Evaluation criteria)
○: 60% or more ◇: 40 to 60%
Δ: 20 to 40%
×: 20% or less

[Polyoxymethylene resin molded article (P)]
A polyoxymethylene resin molded article (P) was prepared using a polyoxymethylene homopolymer (A) as a polyoxymethylene resin shown below, an amide compound (B) and an additive (s).

<Preparation of Polyoxymethylene Homopolymer (A)>
(Polymerization process)
A jacketed 5 L tank polymerizer having a circulation line (inner diameter: 6 mm, length: 2.5 m) and attached a stirrer was filled with 2 L of n-hexane. n-Hexane was circulated by a pump at 20 L / hr. 200 g / hr of dehydrated formaldehyde gas was directly supplied to this circulation line. The catalyst (dimethyl distearyl ammonium acetate) was adjusted to have a molar ratio of 5 × 10 ⁻⁵ to formaldehyde gas, and was supplied to the circulation line immediately before the reactor. Next, chain transfer agent (acetic anhydride) is adjusted to a range of 0.1 to 0.6 g / hr and supplied to n-hexane to compensate for the decrease of the polymerization slurry sent to the end stabilization step. It was added and fed continuously. In this state, polymerization was performed at 58 ° C. to obtain a polymerization slurry. Adjustment of the addition amount of a chain transfer agent was performed so that the resin composition of the melt flow rate shown in Table 1 could be obtained.
(Terminal stabilization process)
Stabilization was carried out by reacting the obtained polymerization slurry in a 1 to 1 mixture of n-hexane and acetic anhydride at 140 ° C. for 2 hours to acetylate molecular ends. The polymer after reaction was collected by filtration to obtain a powder of polyoxymethylene homopolymer (A).

<Amide Compound (B)>
The following amide compounds (B-1) to (B-2) were used as the amide compound (B).
(B-1) / H-3 (manufactured by Asahi Kasei Finechem Co., Ltd.), chemical name: acrylamide-methylene bisacrylamide copolymer, melting point 300 ° C.
(B-2) / Diamide L1940 (made by Daicel Evonik KK), chemical name: polyamide 12, melting point 178 ° C.
<Additive (s)>
The following additives (s-1) to (s-2) were used as the additive (s).
(S-1): Antioxidant / Irganox 245 (manufactured by Ciba Specialty Chemicals Inc.)
(S-2): Stabilizer / sebacic acid dihydrazide (manufactured by Nippon Finechem Co., Ltd.)

[Preparation of Resin Composition (p)]
(Preparation of Resin Composition (p-1))
Granulation process
After confirming that the product temperature is 80 ° C. in a gear oven (set at 80 ° C.) in a nitrogen atmosphere and drying it for 3 hours, the powder of the polyoxymethylene homopolymer (A) collected by filtration is dried at normal temperature 24 I left for a while.
100 parts by mass of the polyoxymethylene homopolymer (A), 0.05 parts by mass of the amide compound (B-1), 0.2 parts by mass of the additive (s-1), and 0. 1 part of the additive (s-2) 05 parts by mass were added and mixed for 1 minute with a Henschel mixer. After that, a screw type twin screw extruder with vacuum vent set at 200 ° C. (BT-30, L / D = 44, L: raw material for twin screw extruder). The screw rotation speed is 80 rpm based on the distance (m) from the supply port to the discharge port, D: inner diameter (m) of the twin-screw extruder, and melt kneading is performed at 20 amps to obtain pellets of the resin composition (p-1) I got The obtained pellet is melt-kneaded twice (20 times in total) (total 3 times) at a screw rotation speed of 80 rpm with a vacuum vented screw type twin screw extruder set at 200 ° C., 80 ° C. before measurement, It was dried in a gear oven (GPH-102, manufactured by Espec Corporation) for 2 hours. The dried pellet was subjected to melt flow rate of resin composition (p-1) using melt indexer (F-W01 manufactured by Toyo Seiki Co., Ltd.) in accordance with ISO 1133 (condition D · temperature 190 ° C.) g / 10 min) was measured.

(Preparation of Resin Composition (p-2))
In the <granulation step>, pellets of the resin composition are obtained in the same procedure as the resin composition (p-1) except that the addition amount of the amide compound (B-1) is 0.6 parts by mass. The

(Preparation of Resin Composition (p-3))
In the <granulation step>, the procedure is the same as that of the resin composition (p-1), except that the type of the amide compound to be added is (B-2) and the addition amount is 0.2 parts by mass. Pellets of the resin composition were obtained.

(Preparation of Resin Composition (p-4))
In the <granulation step>, the polyoxymethylene homopolymer (A) is dried at a product temperature of 80 ° C. in a gear oven (set at 80 ° C.) under a nitrogen atmosphere and dried for 3 hours, Do not leave it for a while, add 0.1 mass part of (B-1), add 0.2 mass parts of additive (s-1), screw rotation speed is 100 rmp, 24 amps Then, pellets of the resin composition are obtained in the same procedure as the resin composition (p-1) except that the obtained pellets are not melt-kneaded twice (once melt-kneading). The

(Preparation of Resin Composition (p-5))
Pellets of a resin composition were obtained by the same procedure as the resin composition (p-4) except that in the <granulation step>, the screw rotation speed was 80 rmp and 20 amperes.

(Preparation of Resin Composition (p-6))
In the <granulation step>, after confirming the product temperature at 80 ° C in a gear oven (set at 80 ° C) under a nitrogen atmosphere and drying for 3 hours, leave at room temperature for 24 hours to obtain a powder, Pellets of the resin composition were obtained in the same manner as the resin composition (p-5).

(Preparation of Resin Composition (p-7))
In the <granulation step>, the obtained pellet is melt-kneaded twice (20 times in total) (total 3 times) at a screw rotation speed of 80 rpm with a vacuum-vented screw twin screw extruder set at 200 ° C. The pellet of the resin composition was obtained in the same procedure as the resin composition (p-6) except that pellets were obtained.

(Preparation of Resin Composition (p-8))
In the <granulation step>, the resin composition (p-7) is used except that 0.05 parts by mass of the additive (s-2) is added in addition to 0.2 parts by mass of the additive (s-1) Pellets of the resin composition were obtained by the same procedure.

(Preparation of Resin Composition (p-9))
Pellets of a resin composition were obtained in the same manner as the resin composition (p-5) except that in the <granulation step>, the addition amount of the amide compound was 0.2 parts by mass.

(Preparation of Resin Composition (p-10))
Pellets of a resin composition were obtained by the same procedure as the resin composition (p-6) except that in the <granulation step>, the addition amount of the amide compound was 0.2 parts by mass.

(Preparation of Resin Composition (p-11))
Pellets of a resin composition were obtained in the same manner as in the resin composition (p-7) except that in the <granulation step>, the addition amount of the amide compound was 0.2 parts by mass.

(Preparation of Resin Composition (p-12))
Pellets of a resin composition were obtained by the same procedure as the resin composition (p-8) except that in the <granulation step>, the addition amount of the amide compound was 0.2 parts by mass.

(Preparation of Resin Composition (p-13))
In the <granulation step>, after the addition amount of the amide compound is 0.2 parts by mass, the product temperature is confirmed at 80 ° C. in a gear oven (set at 80 ° C.) under a nitrogen atmosphere, and drying is performed for 3 hours Pellets of a resin composition were obtained in the same manner as the resin composition (p-4), except that the powder was left to stand at room temperature for 24 hours to obtain a powder.

(Preparation of Resin Composition (p-14))
In the <granulation step>, the amount of addition of the amide compound is 0.2 parts by mass, and the obtained pellet is adjusted to a screw rotation speed of 80 rpm with a vacuum vented screw type twin screw extruder set at 200 ° C., 20 amps. The pellets of the resin composition were obtained by the same procedure as the resin composition (p-4) except that the mixture was melt-kneaded twice more and pellets were obtained.

(Preparation of Resin Composition (p-15))
In the <granulation step>, the addition amount of the amide compound was 0.2 parts by mass, and was added to 0.2 parts by mass of the additive (s-1) and 0.05 parts by mass of the additive (s-2) was added Pellets of a resin composition were obtained by the same procedure as (p-4) except for the above.

(Preparation of Resin Composition (p-16, p-17))
The resin composition (p-) was prepared except that the addition amount of the chain transfer agent was adjusted to prepare the polyoxymethylene homopolymer (A) so as to obtain the resin composition of the melt flow rate shown in Table 1. Pellets of the resin composition were obtained in the same manner as in 9).

(Preparation of Resin Composition (p-18))
Pellets of a resin composition were obtained by the same procedure as (p-2) except that in the <granulation step>, the addition amount of the amide compound was changed to 0.2 parts by mass.

(Preparation of Polyoxymethylene Resin Molded Article (P))
The cylinder temperature is set 30 ° C. higher than the melting point of the polyoxymethylene resin composition (p) using an injection molding machine (J110AD manufactured by Japan Steel Works, Ltd.) for the polyoxymethylene resin composition (p) Then, using a mold temperature of 80.degree. C. and a cooling time of 30 seconds, a 60 mm square (3 mm thickness) square polyoxymethylene molded article (P) was produced. The molding of the polyoxymethylene resin molded product (P) was carried out while checking that it was sufficiently filled and that no burrs were released.

[Examples 1 to 12, Comparative Examples 1 to 6]
As Examples 1 to 12 and Comparative Examples 1 to 6, a polyoxymethylene resin molded article (P) was produced using each of the polyoxymethylene resin compositions (p) shown in Table 2 as described above. As described above, the amount of acetic acid and the amount of total organic carbon extracted in 150 g of water coexisting in an environment of 80 ° C. for 15 days were measured with respect to these polyoxymethylene resin molded articles (P). . Further, with respect to each polyoxymethylene resin composition (p) shown in Table 2, VDA 270, the number of foreign substances and grease resistance were evaluated. The results are shown in Table 2.

  As can be seen from the evaluation results shown in Table 2, the molded product of polyoxymethylene resin of the present embodiment has little odor, and even when continuous molding is performed, the amount of foreign matter generated in the molded product is small and has high grease resistance.

  The molded articles of polyoxymethylene resin of the present invention have less odor and foreign substances, are excellent in grease resistance and high quality, and are therefore used as containers for cosmetics, applications for peripheral parts of instrument panel in automobile interior, and peripheral parts for air conditioners. It has industrial applicability in gear applications in contact with grease, applications as electrical and electronic parts, and various other automotive and industrial applications.

P: Polyoxymethylene resin molded article

Claims (9)

A polyoxymethylene resin molded article comprising 100 parts by mass of a polyoxymethylene resin and 0.1 to 0.5 parts by mass of an amide compound having a melting point of 300 ° C. or higher,
Acetic acid extracted from 150 g of water coexisting in an environment of 80 ° C. for 15 days from one or more of the polyoxymethylene resin molded articles having a total surface area corresponding to the surface area of one rectangular solid of 60 mm × 60 mm × 3 mm A polyoxymethylene resin molded article, wherein the amount is 80 mass ppm or less based on the total mass of the polyoxymethylene resin molded article.   Total organic carbon extracted from 150 g of water coexisting in an environment of 15 days at 80 ° C. from one or more of the polyoxymethylene resin molded articles having a total surface area corresponding to a surface area of a rectangular solid of 60 mm × 60 mm × 3 mm The polyoxymethylene resin molded article according to claim 1, wherein the amount of is 450 ppm by mass or less based on the total mass of the polyoxymethylene resin molded article.   The polyoxymethylene resin molded article according to claim 1 or 2, wherein the amount of the amide compound is 0.2 to 0.5 parts by mass.   The polyoxymethylene resin molded article according to any one of claims 1 to 3, wherein the evaluation result evaluated by the VDA 270 test of the German Automobile Manufacturers Association is 4.0 or less.   The polyoxymethylene resin molded article according to any one of claims 1 to 4, which is used for a cosmetic container, an instrument panel peripheral part or an air conditioner peripheral part in automobile interior, or a gear application in contact with grease. A polyoxymethylene resin composition comprising 100 parts by mass of a polyoxymethylene resin and 0.1 to 0.5 parts by mass of an amide compound having a melting point of 300 ° C. or higher,
Of acetic acid extracted from one single polyoxymethylene resin molded article into 150 g of water coexisting at 80 ° C. for 15 days when molded into a 60 mm × 60 mm × 3 mm rectangular polyoxymethylene resin molded article Polyoxymethylene resin composition characterized in that the amount is 80 mass ppm or less with respect to the mass of the polyoxymethylene resin molded article.   When molded into a rectangular solid polyoxymethylene resin molded article of 60 mm × 60 mm × 3 mm, the whole product is extracted from one of the molded polyoxymethylene resin articles into 150 g of water coexisting under an environment of 15 days at 80 ° C. The polyoxymethylene resin composition according to claim 6, wherein the amount of body carbon is 450 mass ppm or less based on the total mass of the polyoxymethylene resin molded article.   The polyoxymethylene resin composition according to claim 6 or 7, wherein the amount of the amide compound is 0.2 to 0.5 parts by mass.   When molded into a 120 mm × 80 mm × 3 mm rectangular polyoxymethylene resin molded article, an evaluation result of evaluating one of the polyoxymethylene resin molded articles by the VDA 270 test of the German Automotive Industry Association is 4.0 or less The polyoxymethylene resin composition according to any one of claims 6 to 8.