JP2014122298A - Polyacetal resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyacetal resin composition which is excellent in weather (light) resistance and is capable of suppressing generation of formaldehyde from a molded article to a low level and in which oozing out of a blending component or the like is suppressed.SOLUTION: The polyacetal resin composition of the present invention contains: (A) 100 pts.wt. of a polyacetal copolymer; (B) 0.03-0.30 pt.wt. of a hindered phenol-based antioxidant; (C) 0.05-0.8 pt.wt. of a guanamine compound and/or a hydrazide compound; (D) 0.1-1.0 pt.wt. of a hindered amine-based stabilizer which has a weight-average molecular weight of 2,000 or more and is a copolymer of an olefin, a maleic acid, and an amino group-containing piperidine derivative; (E) 0.1-1.0 pt.wt. of a hindered amine stabilizer which has a weight-average molecular weight of less than 700 and in which nitrogen of a piperidine derivative is tertiary; and (F) 0.2-1 pt.wt. of an ultraviolet absorber.

Description

  The present invention relates to a polyacetal resin composition.

  Polyacetal resin has excellent properties, and its molded products are used in a wide range of fields. However, due to its chemical structure, it is easily decomposed in a heated oxidizing atmosphere or under acidic or alkaline conditions. Have Therefore, the problem of the polyacetal resin is that it has high thermal stability and suppresses generation of formaldehyde from the molding process or the molded product. If the thermal stability is low, the polymer is decomposed by heating in a processing step such as extrusion or molding, and deposits (mold deposit) on the mold are generated, and the moldability and mechanical properties are reduced. Formaldehyde generated by decomposition is chemically active, and it becomes formic acid by oxidation and adversely affects the heat resistance of polyacetal resin, or if polyacetal resin with a large amount of formaldehyde is used for parts of electrical and electronic equipment, etc. In some cases, the generated formaldehyde or formic acid which is an oxide thereof corrodes metal contact parts, or causes discoloration or contact failure due to adhesion of organic compounds. In addition, the amount of formaldehyde generated from polyacetal resin moldings under normal use conditions is extremely small, but the generated formaldehyde itself is one of the factors that contaminate the working environment in the parts assembly process and the environment in which the final product is used. .

  Therefore, antioxidants and other stabilizers are blended in order to stabilize the polyacetal resin. As the antioxidant added to the polyacetal resin, a sterically hindered phenol compound (hindered phenol), a sterically hindered amine compound (hindered amine), and the like are known, and other stabilizers include melamine, polyamide, Alkali metal hydroxides and alkaline earth metal hydroxides are used. Usually, the antioxidant is used in combination with other stabilizers. However, it is difficult to significantly reduce formaldehyde generated, particularly formaldehyde generated from a molded product, by simply blending such a general-purpose stabilizer with a polyacetal resin having normal formaldehyde quality.

  Furthermore, in order to solve the above problems and reduce the amount of formaldehyde generated, a polyacetal resin composition containing various compounds is disclosed. For example, Patent Document 1 discloses a polyacetal resin composition containing a polyacetal resin and a glyoxydiureido compound, and Patent Document 2 discloses a polyacetal resin and a cyclic nitrogen-containing compound (glycocyanin such as creatinine or the like). A polyacetal resin composition containing a derivative) is disclosed. Patent Document 3 discloses a polyacetal resin, at least one processing stabilizer selected from polyalkylene glycol, fatty acid ester, fatty acid amide and fatty acid metal salt, and at least selected from urea or a derivative thereof and an amidine derivative. A polyacetal resin composition containing one type of inhibitor is disclosed. Patent Document 4 selects from a polyacetal resin, a hindered phenol-based compound, a spiro compound having a triazine ring, a processing stabilizer and a heat stabilizer. A polyacetal resin composition composed of at least one of the above-described materials is disclosed. Patent Document 5 discloses a polyacetal resin composition in which a polyacetal resin is blended with a guanamine derivative such as benzoguanamine as a stabilizer.

  Patent Document 6 discloses a polyacetal resin composition composed of a polyacetal copolymer having a specific terminal group and a formaldehyde inhibitor. As the formaldehyde inhibitor, a guanamine compound, a urea compound, a carboxylic acid hydrazide compound, or the like is disclosed. Is disclosed.

  Further, in order to improve the weather resistance of the polyacetal resin, Patent Document 7 discloses a composition in which a benzotriazole-based material and a hindered amine-based material are added and coexisted with the polyacetal resin. In Patent Document 8, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, which is an antioxidant, and bis-, which is a light stabilizer, are disclosed. [N-methyl-2,2,6,6-tetramethyl-4-piperidinyl] sebacate and 2- [2′-hydroxy-3 ′, 5′-bis- (α, α-dimethyl) which is an ultraviolet absorber It is disclosed that weather resistance (light) resistance and thermal stability can be improved by containing benzyl) phenyl] benzotriazole. In addition, in Patent Document 9, a hindered amine stabilizer having a tertiary nitrogen of a piperidine derivative having a sterically hindering group and a hindered phenolic antioxidant are used in combination in a strictly controlled blending amount and blending ratio. By doing so, it is disclosed that the antagonistic action of both can be suppressed and the weather resistance (light) resistance and thermal stability can be improved.

  According to the techniques disclosed in Patent Documents 1 to 6, the generation of formaldehyde from the polyacetal resin can be remarkably reduced, and according to the techniques disclosed in Patent Documents 7 to 9, the weather resistance superior to the polyacetal resin can be obtained. Can be granted.

Japanese Patent Laid-Open No. 10-182928 (Claim 1) JP-A-11-335518 (Claim 1) JP-A-12-26704 (Claim 1) JP 2003-113289 A (Claim 1) JP-A-62-190248 JP 2005-112995 A JP-A 61-36339 JP-A-6-256623 JP 2008-7676 A

  However, it is difficult to simply combine these technologies in order to obtain a resin material that can cope with the diversification of required performance and high specifications for recent resin products. In particular, in weathering tests and accelerated tests thereof, there is a concern that the weathering (light) performance may deteriorate due to the reaction between an acid component such as formic acid generated during the deterioration process of the polyacetal resin and the amino group of the piperidine derivative in the hindered amine stabilizer. . On the other hand, even if it is a hindered amine stabilizer that is tertiary by modification of the amino group of the piperidine derivative, a single type of addition exhibits stable weathering (light) performance over a long period of time in a diversified evaluation method Things are difficult.

  An object of the present invention is to provide a polyacetal resin composition that is extremely excellent in weather resistance (light), can suppress generation of formaldehyde from a molded product to a low level, and also suppresses exudation of compounding components and the like. is there.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the object can be achieved by strict control of a combination of specific blending components, blending amount and blending ratio, and has completed the present invention. More specifically, the present invention provides the following.

  (1) The present invention comprises (A) 100 parts by weight of a polyacetal copolymer, (B) 0.03 to 0.30 parts by weight of a hindered phenol antioxidant, and (C) a guanamine compound and / or a hydrazide compound. 0.05 to 0.8 parts by weight, and (D) a hindered amine stabilizer having a weight average molecular weight of 2000 or more and a copolymer of an olefin, maleic acid and an amino group-containing piperidine derivative 0.1 to 1. 0 part by weight; (E) 0.1 to 1.0 part by weight of a hindered amine stabilizer having a weight average molecular weight of less than 700 and a tertiary nitrogen of the piperidine derivative; and (F) an ultraviolet absorber 0.2 to 0.2 A polyacetal resin composition containing 1.0 part by weight.

(2) In the present invention, the component (D) is a copolymer of a C _{20 to} C ₂₄ olefin, maleic anhydride, and 4-amino-2,2,6,6-tetramethylpiperidine. The component (E) is bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and / or methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate. , (1) is a polyacetal resin composition.

  (3) Moreover, this invention is a polyacetal resin composition as described in (1) or (2) in which the said (F) component contains a benzotriazole type ultraviolet absorber or a triazine type ultraviolet absorber at least.

  (4) Moreover, this invention is a polyacetal resin composition in any one of (1) to (3) which further contains at least one of (G) fatty acid ester or polyalkylene glycol.

  According to the present invention, the blending components to be used are selectively combined, and particularly the blending amount and blending ratio of the two selective hindered amine stabilizers are strictly controlled, so the weather resistance (light) is extremely excellent. Generation | occurrence | production of formaldehyde from a molded article can be suppressed to a low level, and also a seepage etc. can be suppressed.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to.

<Polyacetal resin composition>
The polyacetal resin composition of the present invention includes (A) a polyacetal copolymer (hereinafter also referred to as “(A) component”) and (B) a hindered phenol-based antioxidant (hereinafter also referred to as “(B) component”). ), (C) a guanamine compound and / or a hydrazide compound (hereinafter also referred to as “component (C)”), (D) a weight average molecular weight of 2000 or more, an olefin, maleic acid, and an amino group-containing piperidine derivative. A hindered amine stabilizer (hereinafter also referred to as “component (D)”), and (E) a hindered amine stabilizer having a weight average molecular weight of less than 700 and a nitrogen of the piperidine derivative being tertiary. (Hereinafter also referred to as “component (E)”) and (F) an ultraviolet absorber (hereinafter also referred to as “component (F)”).

[(A) polyacetal copolymer]
The polyacetal resin composition of the present invention contains a polyacetal copolymer as the component (A). The polyacetal copolymer is a resin having an oxymethylene group (—OCH ₂ —) as a main constituent unit and other comonomer units in addition to the oxymethylene unit, and generally a formaldehyde or a cyclic oligomer of formaldehyde as a main monomer. It is produced by copolymerizing a compound selected from cyclic ether and cyclic formal as a comonomer, and is usually stabilized against thermal decomposition by removing an unstable portion at the end by hydrolysis. In particular, it is common to use trioxane, which is a cyclic trimer of formaldehyde, as the main monomer. Trioxane is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst, and is used after being purified by a method such as distillation. As described below, trioxane used for polymerization is preferably one having as little content of impurities as water, methanol, formic acid and the like. Examples of the cyclic ether and cyclic formal as comonomer include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, oxetane, tetrahydrofuran, trioxepane, 1,3-dioxane, 1,3-dioxolane, propylene glycol formal, diethylene glycol formal, Examples include ethylene glycol formal, 1,4-butanediol formal, 1,6-hexanediol formal, and the like. Further, a compound capable of forming a branched structure or a crosslinked structure can be used as a comonomer (or termonomer). Examples of such a compound include methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, and 2-ethyl-hexyl. Alkyl or aryl glycidyl ethers such as glycidyl ether and phenyl glycidyl ether, alkylene glycols such as ethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, and butanediol diglycidyl ether, and diglycidyl ethers of polyalkylene glycols. These comonomers can be used alone or in combination of two or more.

  The polyacetal copolymer as described above can be generally obtained by cationic polymerization using a cationic polymerization catalyst by adding an appropriate amount of molecular weight regulator. The molecular weight regulator used, cationic polymerization catalyst, polymerization method, polymerization apparatus, deactivation treatment of the catalyst after polymerization, terminal stabilization treatment method of the crude polyacetal copolymer obtained by the polymerization, etc. are known from many literatures. Basically, any of them can be used.

  The molecular weight of the polyacetal copolymer used in the present invention is not particularly limited, but those having a weight average molecular weight (Mw) of about 10,000 to 400,000 are preferable. Further, it is preferable that the melt index (measured at 190 ° C. under a load of 2.16 kg according to ASTM-D1238) of 0.1 to 100 g / 10 minutes, which is an index of resin fluidity, is more preferably 0.5. ~ 80 g / 10 min.

  The polyacetal copolymer (A) used in the present invention is required to have specific terminal properties as described above. Specifically, the hemi-formal terminal group amount is 1.0 mmol / kg or less, formyl It is essential that the amount of terminal groups is 2.0 mmol / kg or less and the amount of unstable terminal groups is 0.5% by weight or less.

Here, the hemiformal terminal group is represented by —OCH ₂ OH, and is also referred to as a hydroxymethoxy group or a hemiacetal terminal group. The formyl end group is represented by -CHO. The amount of such hemi-formal end groups and formyl end groups can be determined by ¹ H-NMR measurement, and the specific measurement method can be referred to the method described in JP-A No. 2001-11143. The unstable terminal group amount is the amount of a portion which is present at the terminal portion of the polyacetal copolymer and is unstable and easily decomposed with respect to heat or a base. The amount of such unstable end groups is as follows: 1 g of polyacetal copolymer is placed in a pressure-resistant airtight container with 100 ml of 50% (volume%) aqueous methanol solution containing 0.5% (volume%) ammonium hydroxide, and at 180 ° C. for 45 minutes. The amount of formaldehyde decomposed and dissolved in the solution obtained by cooling and opening after heat treatment was quantified, and expressed in weight% with respect to the polyacetal copolymer.

  When the polyacetal copolymer (A) to be used does not have the above terminal properties and exceeds the upper limit value, it is not possible to obtain a polyacetal resin composition in which the amount of formaldehyde generated is sufficiently reduced, and further, thermal history It is difficult to maintain the amount of formaldehyde generated by repeating the above at a low level. From such a viewpoint, the component (A) used in the present invention preferably has a hemiformal terminal group content of 0.8 mmol / kg or less, more preferably 0.6 mmol / kg or less. Further, the formyl end group amount is preferably 1.5 mmol / kg or less, more preferably 1.0 mmol / kg or less. The amount of unstable terminal groups is preferably 0.4% by weight or less, more preferably 0.3% by weight or less. The lower limit of the amount of hemi-formal end groups, formyl end groups, and unstable end groups is not particularly limited.

  As described above, the polyacetal polymer (A) having specific terminal characteristics can be produced by reducing impurities contained in the monomer and comonomer, selecting the production process, optimizing the production conditions, and the like.

  Although the specific example of the method of manufacturing the polyacetal polymer (A) which has the specific terminal characteristic which satisfy | fills the requirements of this invention for the following is given, it is not limited to this method at all.

First, it is important to reduce impurities such as water, alcohol (for example, methanol), and acid (for example, formic acid) contained in the monomer and comonomer, which are active impurities that form unstable terminals in the polymerization system. In addition, the total amount of these active impurities is preferably 1 × 10 ⁻² mol% or less, more preferably 5 × 10 ⁻³ mol% or less, based on all monomers in the reaction system. Naturally, if the content is excessive, it is not preferable for obtaining a polyacetal polymer having a small number of unstable terminal portions. It should be noted that chain transfer agents that do not form unstable ends, for example, low molecular weight linear acetals having both ends having an alkoxy group, such as methylal, are contained in an arbitrary amount to adjust the molecular weight of the polyacetal polymer. Can do.

Next, the amount of catalyst used during the polymerization reaction is also an important requirement. When a catalyst comprising boron trifluoride or a coordination compound thereof is used, it is preferably in the range of 5 × 10 ⁻³ to 1 × 10 ⁻² mol%, particularly 1 × 10 ^{−3 to} 7 based on the total monomers. × 10 ⁻³ mol% is preferable. Setting the amount of catalyst in such a limited range is effective in preventing the formation of unstable end portions. If the amount of the catalyst is too large, it is difficult to properly control the polymerization temperature, the decomposition reaction during the polymerization becomes dominant, and it becomes difficult to obtain a polyacetal polymer having a small number of unstable end portions that satisfies the requirements of the present invention. On the other hand, if the amount of the catalyst is too small, it is not preferable because the polymerization reaction rate is lowered and the polymerization yield is lowered.

  The amount and type of comonomer greatly affects the thermal stability of the polyacetal polymer. As the component (A) of the present invention, a compound selected from (A1) trioxane, (A2) cyclic ether and cyclic formal. It is preferable to copolymerize one or more kinds in a ratio (weight ratio) of the former (A1) / the latter (A2) = 99.9 / 0.1 to 80.0 / 20.0, more preferably The former / the latter are copolymerized at a ratio (weight ratio) of 99.5 / 0.5 to 90.0 / 10.0. As the compound (A2) selected from cyclic ether and cyclic formal, ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal, and diethylene glycol formal are particularly preferable.

  As the polymerization method, any conventionally known method can be used, but a continuous bulk polymerization method for obtaining a solid powdery bulk polymer with the progress of polymerization using a liquid monomer is industrially preferable, and the polymerization temperature is 60 to It is desirable to maintain at 105 ° C, particularly 65 to 100 ° C.

  When a catalyst composed of boron trifluoride or a coordination compound thereof is used, a method of deactivating the catalyst after polymerization may be a method such as adding a polymer after polymerization into an aqueous solution containing a basic compound. In order to obtain a polyacetal polymer that satisfies the requirements of the present invention, it is preferable to pulverize and subdivide the polymer obtained by the polymerization reaction and bring it into contact with a deactivator to quickly deactivate the catalyst. For example, a polymer used for deactivation of the catalyst is pulverized, and 80% by weight or more, preferably 90% by weight thereof has a particle size of 1.5 mm or less, and 15% by weight or more, preferably 20% by weight or more is 0.00. It is desirable that the particle size is 3 mm or less. Basic compounds for neutralizing and deactivating the polymerization catalyst include ammonia, amines such as triethylamine, tributylamine, triethanolamine, and tributanolamine, or oxides of alkali metals and alkaline earth metals. , Hydroxides, salts, and other known catalyst deactivators can be used, and these basic compounds are added in an aqueous solution of 0.001 to 0.5% by weight, particularly 0.02 to 0.3% by weight. Is preferred. Moreover, the temperature of the preferable aqueous solution is 10-80 degreeC, Most preferably, it is 15-60 degreeC. Further, after the polymerization is completed, it is preferable that the catalyst is deactivated by promptly adding it to these aqueous solutions.

  Prior to the polymerization, 0.01 to 0.1% by weight of a hindered phenolic antioxidant is added to the monomer in advance in the monomer, and the polymerization is performed in the presence of this to make the polymerization reaction system uniform. By making it exist, depolymerization during polymerization can be suppressed, and post-treatment such as drying after polymerization and oxidative degradation in a stabilization step can also be suppressed.

  Polyacetal polymers with a small amount of unstable terminals can be produced by reducing impurities contained in the monomers and comonomers as described above, selecting the production process, and optimizing the production conditions. It is possible to further reduce the amount of unstable terminals by passing through the conversion step. As the stabilization step, the polyacetal polymer is heated to a temperature equal to or higher than its melting point and processed in a molten state to decompose and remove only unstable parts, or a non-uniform system is maintained in an insoluble liquid medium at 80 ° C. or higher. For example, the unstable end portion may be decomposed and removed by heat treatment at a temperature of 5 ° C.

[(B) hindered phenolic antioxidant]
The polyacetal resin composition of the present invention contains a hindered phenol antioxidant as the component (B). Specific examples of the component (B) include monocyclic hindered phenol compounds, polycyclic hindered phenol compounds linked by a hydrocarbon group or a group containing a sulfur atom, hindered phenol compounds having an ester group or an amide group, etc. Is mentioned. Specific examples of these compounds include 2,6-di-t-butyl-p-cresol, 2,2′-methylenebis (4-methyl-6-t-butylphenol), 4,4′-methylenebis (2,6 -Di-t-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 4,4'-butylidenebis (3-methyl-6-t-butylphenol) 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 4,4′-thiobis (3-methyl-6-tert-butylphenol) ), N-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate, n-octadecyl-2- (4′-hydroxy-3 ′, 5′-di-t) -Butylphenyl) propi Onate, 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], ethylenebis (oxyethylene) bis [3- (3- (5-t- Butyl-4-hydroxy-m-tolyl) propionate], pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,9-bis [2- {3- ( 3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, 2-t-butyl -6- (3'-t-butyl-5'-methyl-2'-hydroxybenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t- Nthylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, di-n-octadecyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate, N, N′-hexamethylenebis (3 5-di-t-butyl-4-hydroxy-dihydrocinnamamide, N, N′-ethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide], N, N '-Tetramethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide], N, N'-hexamethylenebis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionamide], N, N′-ethylenebis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionamide], N, N′-hexa Tylene bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionamide], N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl ] Hydrazine, N, N′-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionyl] hydrazine, 1,3,5-tris (3,5-di-tert-butyl- Examples include 4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, and the like.

  (B) A component can be used individually or in combination of 2 or more types. The ratio of (B) component is 0.03-0.30 weight part with respect to 100 weight part of (A) component. If it is less than 0.03 parts by weight, it is not preferable in that the effect of preventing oxidation is insufficient, and if it is more than 0.30 parts by weight, it is a hindered amine (system) stabilizer (component (D) and component (E). It is not preferable in that the weather resistance (light) property is inferior due to the antagonistic action.

[(C) Guanamine compound and / or hydrazide compound]
The polyacetal resin composition of the present invention contains a guanamine compound and / or a hydrazide compound as the component (C).

[Guanamine compound]
Examples of the guanamine compound include melamine, an aliphatic guanamine compound, an alicyclic guanamine compound, an aromatic guanamine compound, a heteroatom-containing guanamine compound, and the like.

  Aliphatic guanamine compounds include monoguanamines such as valerologamine, caproguanamine, heptanoguanamine, capriloganamin, stealoganaamine, succinoguanamine, gluten guanamine, adipoguanamine, pimeloganamin, suberoguanamine. Examples thereof include alkylene bisguanamines such as guanamine, azeroguanamine, and sebacoguanamine.

  Examples of the alicyclic guanamine compounds include monoguanamines such as cyclohexanecarboguanamine, norbornenecarboguanamine, cyclohexenecarboguanamine, norbornanecarboguanamine, and their cycloalkane residues, which include alkyl groups, hydroxy groups, amino groups, acetamino groups. And derivatives in which 1 to 3 functional groups such as a group, nitrile group, carboxy group, alkoxycarbonyl group, carbamoyl group, alkoxy group, phenyl group, cumyl group, and hydroxyphenyl group are substituted.

  Aromatic guanamine compounds include benzoguanamine and its phenyl residue as alkyl, hydroxy, amino, acetamino, nitrile, carboxy, alkoxycarbonyl, carbamoyl, alkoxy, phenyl, cumyl, hydroxy Derivatives substituted with 1 to 5 functional groups such as phenyl group (for example, toruguanamine, xyloganamine, phenylbenzoguanamine, hydroxybenzoguanamine, 4- (4′-hydroxyphenyl) benzoguanamine, nitrile benzoguanamine, 3,5-dimethyl-4 Monohydroxyamines such as -hydroxybenzoguanamine, 3,5-di-t-butyl-4-hydroxybenzoguanamine, etc.), naphthoguanamine and its naphthyl residues substituted with the above functional groups, Min, isophthalate log guanamine, terephthalic catalog guanamine, naphthalene jig guanamine, Poriguanamin such as biphenylene guanamines, phenylacetamide guanamine, beta-phenylpropyl og guanamine, aralkyl or aralkylene bridging guanamine such as xylylene bis guanamines and the like.

  Examples of the heteroatom-containing guanamine compounds include acetal group-containing guanamines such as 2,4-diamino-6- (3,3-dimethoxypropyl) -s-triazine, [2- (4′-6′-diamino-s -Triazin-2'-yl) ethyl] -1,3-dioxane, [2- (4'-6'-diamino-s-triazin-2'-yl) ethyl] -4-ethyl-4-hydroxymethyl- Dioxane ring-containing guanamines such as 1,3-dioxane, tetraoxospiro ring-containing guanamines such as CTU-guanamine and CMTU-guanamine, 1,3,5-tris [2- (4 ′, 6′-diamino-s -Triazin-2'-yl) ethyl] isocyanurate, 1,3,5-tris [3- (4 ', 6'-diamino-s-triazin-2'-yl) propyl] isocyanur Isocyanuric ring-containing guanamines such as salts, imidazoline ring-containing guanamines such as guanamine compounds described in JP-A-6-179671 and JP-A-7-10871, JP-A-47-41120, Examples thereof include imidazole ring-containing guanamines such as guanamine compounds described in JP-A-3-284675 and JP-A-7-33766, and guanamine compounds described in JP-A 2000-154181.

  Also included are compounds in which the hydrogen of the amino group of the guanamine compound is substituted with an alkoxymethyl group, for example, (mono-tetra) methoxymethylbenzoguanamine, (mono-octa) methoxymethyl CTU-guanamine, and the like.

  Among these guanamine compounds, particularly preferred are melamine, benzoguanamine and CTU-guanamine.

[Hydraside compound]
As the hydrazide compound used in the present invention, aliphatic or alicyclic carboxylic acid hydrazide, aromatic carboxylic acid hydrazide and the like are possible.

  Examples of the aliphatic or alicyclic carboxylic acid hydrazide include lauric acid hydrazide, palmitic acid hydrazide, stearic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, eicosane diacid dihydrazide, sorbic acid hydrazide and the like. Oxyfatty acid hydrazides such as saturated fatty acid hydrazide, α-oxybutyric acid hydrazide, glyceric acid hydrazide, 7,11-octadecadien-1,18-dicarbohydrazide, 1,3-bis (hydrazinocarbonoethyl) -5 Isopropyl hydantoin), tris (hydrazinocarbonylethyl) isocyanurate and the like.

  Examples of the aromatic hydrazide include 1-naphthoic acid hydrazide, 2-naphthoic acid hydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, and 2,6-naphthoic acid dihydrazide.

[Proportion of component (C)]
In this invention, the ratio of (C) component is 0.05-0.8 weight part with respect to 100 weight part of (A) component, and it is preferable that it is 0.07-0.5 weight part. When the amount of the component (C) is less than 0.05 parts by weight, it is not possible to obtain a polyacetal resin composition in which the amount of generated formaldehyde is sufficiently reduced, and further, the amount of formaldehyde generated by repeated thermal history is reduced. It is not preferable because it is difficult to maintain the level. When the amount of the component (C) exceeds 0.8 parts by weight, it is not preferable because problems such as deterioration of mechanical properties and appearance defects due to bleeding occur.

[(D) Hindered amine stabilizer having a weight average molecular weight of 2000 or more and a copolymer of olefin, maleic acid and an amino group-containing piperidine derivative]
The polyacetal resin composition of the present invention contains, as component (D), a hindered amine stabilizer that has a weight average molecular weight of 2000 or more and is a copolymer of an olefin, maleic acid, and an amino group-containing piperidine derivative.

The component (D) is a copolymer of a C _{20 to} C ₂₄ olefin, maleic anhydride, and 4-amino-2,2,6,6-tetramethylpiperidine represented by the following chemical formula. preferable. By using the copolymer, the weather resistance (light) of the polyacetal resin composition can be enhanced without impairing the VOC performance.

  The ratio of (D) component is 0.1-1.0 weight part with respect to 100 weight part of (A) component. If the amount is less than 0.1 part by weight, it is not preferable because sufficient weather resistance (light) may not be obtained. When the amount is more than 1.0 part by weight, it is not preferable in that a problem such as deterioration of mechanical properties and appearance defect due to bleeding occurs.

[(E) Hindered amine stabilizer having a weight average molecular weight of less than 700 and a nitrogen of the piperidine derivative being tertiary]
The polyacetal resin composition of this invention contains the hindered amine stabilizer whose weight average molecular weight is less than 700 and whose nitrogen of a piperidine derivative is tertiary as (E) component.

As an example of the component (E),
Bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate,
Methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate,
Bis (1,2,2,6,6-pentamethyl-4-piperidyl) adipate,
Bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate,
Etc.

Particularly preferred is bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and / or methyl 1,2,2,6,6-pentamethyl-4 represented by the following chemical formula: -Piperidyl sebacate.

  (E) The ratio of a component is 0.1-1.0 weight part with respect to 100 weight part of (A) component. If the amount is less than 0.1 part by weight, it is not preferable because sufficient weather resistance (light) may not be obtained. When the amount is more than 1.0 part by weight, it is not preferable in that a problem such as deterioration of mechanical properties and appearance defect due to bleeding occurs.

  Moreover, it is preferable that ratio (B / (D + E)) with respect to the sum total of (D) component and (E) component of (B) component is 0.03-0.5. If B / (D + E) is smaller than 0.03, the thermal stability may be inferior, and if it is larger than 0.5, the weather resistance may be lowered.

[(F) UV absorber]
The polyacetal resin composition of the present invention contains an ultraviolet absorber as the component (F). The ultraviolet absorber preferably contains at least a benzotriazole-based compound or a triazine-based compound, and one or a combination of two or more compounds can be used.

  As benzotriazole compounds, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4-6-bis (1-methyl-1-phenylethyl) ) Phenol, 2- [5-chloro (2H) -benzotriazol-2-yl) -4-methyl-6- (tert-butyl) phenol, 2,4-di-tert-butyl-6- (5-chloro) Benzotriazol-2-yl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-di-tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1 , 1,3,3-tetramethylbutyl) phenol, 2- (2′-hydroxy-3 ′, 5′-di-isoamylphenyl) benzotriazole and the like And benzotriazoles having an alkyl (C1-6 alkyl) group-substituted aryl group, hydroxyl groups such as 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] benzotriazole, and Benzotriazoles having an aralkyl (or aryl) group-substituted aryl group, and hydroxyl groups and alkoxy (C1-12 alkoxy) group-substituted aryl groups such as 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole Examples thereof include benzotriazoles.

  These benzotriazole compounds can be used alone or in combination of two or more.

  Among these benzotriazole compounds, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2- (2H-benzotriazol-2-yl) ) -4,6-di-tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol and the like are preferable.

  As a triazine compound, Tinuvin 1600 (manufactured by BASF Japan), 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 85% 2 -(4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl and oxirane [(C10-C16, mainly C12-C13 alkyloxy) methyl] Reaction product with oxirane, 15% 1-methoxy-2-propanol, 2- (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine And the reaction product of (2-ethylhexyl) -glycidic acid ester, 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-di Toxiphenyl) -1,3-5-triazine, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- [2- (2-ethylhexanoyloxy) ethoxy]- Phenol, ADK STAB LA-F70 (made by ADEKA) can be mentioned. These triazine compounds can be used alone or in combination of two or more.

  In this invention, content of (F) component is 0.2-1.0 weight part with respect to 100 weight part of polyacetal copolymers (A), and is 0.4-0.8 weight part. It is preferable. When the component (F) is less than 0.2 parts by weight, it is not preferable in that a polyacetal resin composition excellent in weather resistance cannot be obtained, and when it exceeds 1.0 parts by weight, mechanical properties are deteriorated and stained. It is not preferable in that problems such as poor appearance due to sticking occur.

  Moreover, it is preferable that ratio ((D + E) / F) with respect to (F) component of the sum total of (D) component and (E) component is 0.5-2.0. When (D + E) / F is less than 0.5, it is not preferable in terms of deterioration of weather resistance, and when it is more than 2.0, problems of bleeding out of a hindered amine stabilizer and deterioration of weather resistance may occur. It is not preferable.

  Moreover, it is preferable that the sum total (D + E + F) of (D) component, (E) component, and (F) component is 0.5-1.5 weight part with respect to 100 weight part of (A) component. When D + E + F is less than 0.5 parts by weight, it is not preferable in that the weather resistance can be lowered, and when it is more than 1.5 parts by weight, it is not preferable in that a problem of bleeding may occur.

[(G) fatty acid ester or polyalkylene glycol]
Although not an essential component, the polyacetal resin composition of the present invention preferably further contains at least one of (G) fatty acid ester or polyalkylene glycol as an optional component.

[Fatty acid ester]
The fatty acid that is a constituent of the fatty acid ester is one or more saturated or unsaturated fatty acids. Examples of such fatty acids include acetic acid, propionic acid, butyric acid, caproic acid, capric acid, undecylic acid, Hivalic acid, caprylic acid, lauric acid, tridecyl acid, isotridecyl acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, 12 hydroxystearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, Examples include heptacosanoic acid, montanic acid, mellic acid, laceric acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, arachidonic acid, cetreic acid, erucic acid, and the like, and preferably fatty acids having 12 or more carbon atoms.

On the other hand, as the alcohol which is a constituent component of the fatty acid ester, any of a monohydric alcohol (for example, stearyl alcohol) and a polyhydric alcohol can be used, but a polyhydric alcohol is preferable. Examples of the polyhydric alcohol include C _2-6 alkylene glycol such as ethylene glycol, propylene glycol and tetramethylene glycol, diethylene glycol, glycerin and pentaerythritol. In addition, poly C _2-6 oxyalkylene glycol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene-polyoxypropylene copolymer (random or block copolymer, etc.), polyoxyethylene polyoxypropylene glyceryl Copolymers such as ether and polyoxyethylene polyoxypropylene monobutyl ether are also mentioned as preferred polyhydric alcohols for constituting the fatty acid ester. More preferred polyoxyalkylene glycols are polymers having oxyethylene units, such as polyethylene glycol, polyoxyethylene polyoxypropylene copolymers and derivatives thereof. The number average molecular weight of the polyoxyalkylene glycol is 1 × 10 ³ to 1 × 10 ⁶ (for example, 1 × 10 ^{3 to} 5 × 10 ⁵ ), preferably 2 × 10 ³ to 1 × 10 ⁵ (for example, 2 × 10 ^{3 to} 5 × 10 ⁴ ).

  Preferred fatty acid esters include esters of fatty acids having 12 or more carbon atoms and polyalkylene glycols having an average degree of polymerization of about 20 to 300.

[Polyalkylene glycol]

  As the polyalkylene glycol, at least one selected from homopolymers and copolymers such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and polyglycerin can be used, and a polyalkylene having an average degree of polymerization of about 20 to 300 Glycol is preferred.

  The component (G) is not an essential component, but if the component (G) is contained, an effect of promoting improvement in weather resistance is produced. The proportion of component (G) is preferably 0.01 to 5.0 parts by weight and more preferably 0.05 to 2.0 parts by weight with respect to 100 parts by weight of component (A).

[(H) Other ingredients]
The polyacetal resin composition of the present invention may further contain an organic carboxylic acid metal salt, a metal oxide, and a metal hydroxide as (H) other components in order to improve thermal stability, long-term thermal stability, and the like. Good.

  As the organic carboxylic acid forming the organic carboxylic acid metal salt, various aliphatic carboxylic acids having about 1 to 34 carbon atoms can be used, saturated aliphatic monocarboxylic acid, saturated aliphatic dicarboxylic acid, unsaturated fat. Group monocarboxylic acid, unsaturated aliphatic dicarboxylic acid, and oxyacids thereof. These aliphatic carboxylic acids may have a hydroxyl group. Further, it may be a copolymer of a polymerizable unsaturated carboxylic acid ((meth) acrylic acid, maleic acid, fumaric acid, maleic anhydride, monoethyl maleate, etc.) and an olefin. Specific examples of organic carboxylic acid metal salts include alkali metal organic carboxylates such as lithium citrate, potassium citrate, sodium citrate, lithium stearate, lithium 12-hydroxystearate, magnesium acetate, calcium acetate, Examples thereof include alkaline earth metal organic carboxylates such as magnesium oxide, calcium citrate, calcium stearate, magnesium stearate, magnesium 12-hydroxystearate, and calcium 12-hydroxystearate, ionomer resins, and the like. Of these organic carboxylic acid metal salts, alkaline earth metal salts such as calcium citrate, magnesium stearate, calcium stearate, magnesium 12-hydroxystearate, and calcium 12-hydroxystearate and ionomer resins are preferred.

  As the metal oxide and metal hydroxide, calcium oxide, magnesium oxide, zinc oxide, calcium hydroxide, magnesium hydroxide and the like are preferable.

  The polyacetal resin composition of the present invention further includes an impact resistance improver, a gloss control agent, a slidability improver, a filler, a colorant, a nucleating agent, a release agent, an antistatic agent, a surfactant, Antibacterial agents, antifungal agents, fragrances, foaming agents, compatibilizers, physical property improvers (boric acid or derivatives thereof), fragrances, and the like can be blended without impairing the purpose of the present invention, Various characteristics according to each additive can be improved. In addition, antioxidants, heat stabilizers, processability improvers and the like other than those described above can be used in combination.

  Examples of the impact resistance improver include thermoplastic polyurethane resins, acrylic core-shell polymers, thermoplastic polyester elastomers, styrene elastomers, olefin elastomers, polyamide elastomers, rubber components (natural rubber, etc.), and the like.

  Gloss control agents include acrylic core-shell polymers, thermoplastic polyurethanes, thermoplastic polyester elastomers, polyamide elastomers, alkyl (meth) acrylate homo- or copolymers (polymethyl methacrylate, etc.), polycarbonate resins, styrene resins ( Polystyrene, AS resin, AES resin, etc.), olefinic resins (polypropylene, cyclic polyolefin, etc.) and the like.

  Examples of the slidability improver include olefin polymers (polyethylene, polypropylene, copolymers of ethylene and α-olefin, modified products thereof such as acid anhydrides), waxes (polyethylene wax, etc.), silicone oils and silicones. Resin, fluorine resin (polytetrafluoroethylene, etc.), fatty acid ester and the like are included.

  As fillers, inorganic or organic fibrous fillers such as glass fiber, carbon fiber, boron fiber, potassium titanate fiber, metal fiber, aramid fiber, plate-like filler such as glass flake, mica, graphite, milled fiber, Examples thereof include powdery fillers such as glass beads, glass balloons, talc, kaolin, silica, diatomaceous earth, clay, wollastonite, alumina, graphite fluoride, silicon carbide, boron nitride, and metal powder.

  Examples of the release agent include long chain fatty acid amides, and acid amides (monoamides, bisamides, etc.) of long chain fatty acids (monovalent or divalent long chain fatty acids) and amines (monoamines, diamines, polyamines, etc.). ) Can be used. Examples of the monoamide include capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide, behenic acid amide, montanic acid amide, etc. Examples include primary acid amides of unsaturated fatty acids such as amides, secondary acid amides of saturated and / or unsaturated fatty acids and monoamines such as stearyl stearic acid amide and stearyl oleic acid amide. The bisamide includes bisamides of C1-6 alkylene diamine (especially C1-2 alkylene diamine) and the fatty acid, and specific examples thereof include ethylenediamine-dipalmitic acid amide, ethylenediamine-distearic acid amide ( Ethylene bisstearylamide), hexamethylenediamine-distearic acid amide, ethylenediamine-dibehenic acid amide, ethylenediamine-dimantanoic acid amide, ethylenediamine-dioleic acid amide, ethylenediamine-dierucic acid amide, etc., and ethylenediamine- (stearic acid amide). Bisamide having a structure in which different acyl groups are bonded to the amine moiety of alkylenediamine such as oleic acid amide can also be used. A preferred fatty acid amide is bisamide.

  Various dyes and pigments can be used as the colorant. Examples of the dye include azo dyes, anthraquinone dyes, phthalocyanine dyes, and naphthoquinone dyes. As the pigment, both inorganic pigments and organic pigments can be used, and as inorganic pigments, titanium pigments, zinc pigments, carbon black, iron pigments, molybdenum pigments, cadmium pigments, lead pigments, cobalt pigments and Examples of the organic pigments include azo pigments, anthraquinone pigments, phthalocyanine pigments, quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, dioxazine pigments and selenium pigments. Etc. can be illustrated. Of these, the use of carbon black, titanium oxide, phthalocyanine pigments, and perylene pigments, which are colorants having a high light shielding effect, can also improve weather resistance (light). The amount of the colorant to be blended is not particularly limited, and a general amount for coloring purposes is used.

[Production Method of Polyacetal Resin Composition]
The manufacturing method of the polyacetal resin composition of this invention is not specifically limited, It can prepare by the various methods conventionally known as a preparation method of a resin composition. For example, (1) a method in which all components constituting the composition are mixed, and this is supplied to an extruder and melt-kneaded to obtain a pellet-like composition; (2) a part of the components constituting the composition The remaining components are fed from the main feed port of the extruder through the side feed port and melt-kneaded to obtain a pellet-like composition. (3) Once the pellets having different compositions are prepared by extrusion or the like, the pellets are mixed Thus, a method of adjusting to a predetermined composition can be employed.

  In the preparation of the composition using an extruder, it is preferable to use an extruder having one or more devolatilization vent ports, and further, water or a low boiling point at any location from the main feed port to the devolatilization vent port. It is preferable to supply about 0.1 to 10 parts by weight of alcohol with respect to 100 parts by weight of the polyacetal resin, and devolatilize and remove formaldehyde and the like generated in the extrusion process from the devolatilization vent port together with water and low-boiling alcohols. Thereby, the amount of formaldehyde generated from the polyacetal resin composition and its molded product can be further reduced.

  The present invention also includes recycling of a molded article comprising the polyacetal resin composition and the colored polyacetal resin composition according to the above. Specifically, a recycled resin composition obtained by melt-kneading and extruding a molded article made of these resin compositions or a pulverized product thereof alone or together with a resin material or molded article having the same or different composition, and these It is a recycled molded product obtained by melt-kneading and molding a molded product comprising the above resin composition or a pulverized product thereof alone or together with a resin material or molded product having the same or different composition. In this way, the recycled resin composition and the recycled molded product prepared by repeating the melting heat history also have the formaldehyde generation amount kept at a very low level, similarly to the polyacetal resin composition that is the basis thereof. It is.

  In the present invention, a colorant is added to the polyacetal resin composition, and melt kneading is performed using a extruder having a vent port while degassing from the vent at a reduced pressure of −400 mmHg or less (absolute pressure of 360 mmHg or less). Also included are polyacetal resin compositions prepared by: The degree of reduced pressure is preferably −500 mmHg or less (absolute pressure 260 mmHg or less), more preferably −600 mmHg or less (absolute pressure 160 mmHg or less). The colored polyacetal resin composition prepared by receiving such a heat history of melting also has a formaldehyde generation amount kept at a very low level, similarly to the polyacetal resin composition as a basis.

  Molded articles formed from the polyacetal resin composition of the present invention and molded articles formed from a polyacetal resin composition prepared by adding a colorant to the polyacetal resin composition have very little formaldehyde generation. Specifically, the amount of formaldehyde generated by the measurement method described in the Examples section can be 2.0 μg / g or less per unit weight of the molded product, preferably 1.0 μg / g or less, more preferably 0. .6 μg / g or less is possible. This is an extremely low level compared to the amount of formaldehyde generated from a molded product made of a commercially available polyacetal resin being about 5 to 20 μg / g per unit weight. Further, these molded products or pulverized products thereof are collected, molded products made of a recycled resin composition prepared by melt kneading treatment, or molded products obtained by melt-kneading and directly molding the collected molded products or pulverized products thereof. The product has a very small amount of formaldehyde generated as described above, and the amount of formaldehyde generated is close to the above level.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and demonstrated concretely, this invention is not limited to these Examples.

<Examples and Comparative Examples>

[Preparation of component (A)]
Using a biaxial paddle type continuous polymerization machine, 0.03% by weight of ethylenebis (oxyethylene) bis [3- (3- (5-t- (Butyl-4-hydroxy-m-tolyl) propionate-containing 1,3-dioxolane 2.5% (in all monomers) added continuously, and at the same time boron trifluoride catalyzed ( was polymerized as catalyst concentration 2 × ¹⁰ -3 mol%). Note that the impurity concentration in the monomer used at this time, the water 3 × ¹⁰ -3 mol%, methanol 1 × ¹⁰ -3 mol%, formic acid 1 × It was 10 ⁻³ mol%.

  About the polymer discharged | emitted from the discharge port of the superposition | polymerization, immediately after discharge | emission, while adding and grind | pulverizing the aqueous solution containing 1000 ppm of triethylamine, it stirred. Thereafter, centrifugation and drying were performed to obtain a polymer in which the catalyst was deactivated.

  This polymer is supplied to a twin screw extruder having a vent port, melted and kneaded at a resin temperature of about 220 ° C., and the unstable end is removed while performing devolatilization under reduced pressure at the vent port, thereby forming a pellet polymer. Got.

  Next, using a cylindrical pressure-resistant container capable of keeping heat, the above pellet-shaped polymer was continuously supplied from the upper part, and the treatment was performed for 8 hours while supplying a 500 ppm triethylamine aqueous solution at 135 ° C. from the lower part. . Then, centrifugation and drying were performed, and the polyacetal copolymer which concerns on (A) component was obtained. The polyacetal copolymer had a hemi-formal terminal group content of 0.38 mmol / kg, a formyl terminal group content of 0.03 mmol / kg, an unstable terminal group content of 0.15 wt%, and a melt index of 9 g. / 10 minutes.

  The hemi-formal terminal group amount and formyl group terminal group amount of the polyacetal copolymer were measured according to the method described in JP-A-2001-11143 using an AVANCE400 FT-NMR apparatus manufactured by Bruker Co., Ltd. Is the value (mmol / kg) obtained by

  The amount of unstable terminal groups was determined by adding 1 g of a polyacetal copolymer together with 100 ml of a 50% (volume%) aqueous methanol solution containing 0.5% (volume%) ammonium hydroxide in a pressure-resistant sealed container. The amount of formaldehyde decomposed and dissolved in a solution obtained by heat treatment for minutes and then cooling and opening is quantified and expressed in weight% with respect to the polyacetal copolymer.

  Moreover, the said melt index is the value (g / 10min) calculated | required on conditions of 190 degreeC and 2160g according to ASTM-D1238.

[About component (B)]
As the component (B), either the following (B1) or (B2) was used.
(B1): Ethylenebis (oxyethylene) bis [3- (3- (5-t-butyl-4-hydroxy-m-tolyl) propionate] (Product name: IRGANOX245, manufactured by BASF Japan Ltd.)
(B2): Pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (Product name: IRGANOX1010, manufactured by BASF Japan Ltd.)

[About component (C)]
As the component (C), any one or more of the following (C1) to (C4) was used.
(C1): Melamine (C2): Benzoguanamine (C3): Sebacic acid dihydrazide (C4): Isocyanurate of isophorone diisocyanate

[About component (D)]
As component _(D), a copolymer of C 20 olefins _{-C 24} and a maleic anhydride of 4-amino-2,2,6,6-tetramethylpiperidine (product name: Uvinul 5050H, manufactured by BASF Japan Ltd.) Was used.

[(D) 'component]
As component (D) ′, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6, -pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl- A condensate with 3,9- (2,4,8,10-tetraoxaspiro [5,5] undecane) -diethanol (product name: ADK STAB LA-63P, manufactured by ADEKA) was used.

[About (E) component]
As the component (E), a mixture of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (product name: Tinuvin 765, manufactured by BASF Japan Ltd.) was used.

[(E) 'component]
As a component (E) ′, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (product name: Tinuvin 622, manufactured by BASF Japan Ltd.) was used.

[About (E) '' component]
As the (E) ″ component, either (E ″ 1) or (E ″ 2) below was used.
(E ″ 1): N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl) -N, N′-diformylhexamethylenediamine (product name: Uvinul 4050FF, BASF Japan Ltd.) Made)
(E ″ 2): Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (Product name: Tinuvin 770, manufactured by BASF Japan)

[About (F) component]
As the component (F), the following (F1) and / or (F2) were used.
(F1): 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (product name: Tinuvin 234, manufactured by BASF Japan Ltd.)
(F2): Tinuvin 1600 (manufactured by BASF Japan)

[About component (G)]
As the component (G), the following (G1) and / or (G2) were used.
(G1): Polyethylene glycol monostearate (G2): Glycerol monostearate

[About (H) component]
As the component (H), the following (H1) and / or (H2) were used.
(H1): 12-hydroxycalcium stearate (H2): ethylenebisstearic acid amide

[Preparation of polyacetal resin composition]
A 30-mm diameter twin-screw extruder having one vent port after pre-blending other components in the proportions shown in Table 1 to 100 parts by weight of component (A) obtained by the above [Preparation of component (A)] And then melt-mixed (extrusion conditions: L / D = 35, extrusion temperature = 200 ° C., screw rotation speed = 120 rpm, vent vacuum = −700 mmHg, discharge amount = 18 kg / hr), Example And the polyacetal resin composition which concerns on a comparative example was prepared.

[Evaluation]
Using the polyacetal resin compositions according to Examples and Comparative Examples, a flat test piece having a predetermined size was molded by an injection molding machine with a cylinder temperature set at 190 ° C., and various evaluations were made on this molded product. Went.

[Evaluation of the amount of formaldehyde generated from molded products]
Two flat test pieces of 100 mm × 40 mm × 2 mm (total weight of about 22 g are precisely weighed) are sealed by hanging on a lid of a polyethylene bottle (capacity 1 L) containing 50 ml of distilled water, and a temperature of 60 in a thermostat. The mixture was allowed to stand at 3 ° C. for 3 hours and then allowed to stand at room temperature for 1 hour. The amount of formaldehyde generated from a flat test piece and absorbed in distilled water in a polyethylene bottle was determined according to JIS K0102, 29 (formaldehyde term), and the amount of formaldehyde generated per unit weight (μg / g) was determined. Calculated. The results are shown in Tables 3 and 4.

[Evaluation of fogging]
Evaluation of fogging was performed according to ISO6452. As a test piece, a disk having a diameter of 80 mm and a thickness of 2 mm was used, the temperature of the heating tank was 100 ° C., the temperature of the cooling plate was 21 ° C., and the heating time was 18 hours. The aluminum foil attached to the cooling plate was weighed before and after the test (unit: mg), and the difference in weight before and after the test was taken as the value of Fogging. The results are shown in Tables 3 and 4.

[Evaluation of weather resistance (light)]
The evaluation of weather resistance (light) was performed in accordance with the standard for automobile interior SAE J1885. In the irradiation cycle, one cycle was 288 minutes, of which 228 minutes were in an irradiation state (Light, dry), and 60 minutes were in a non-irradiation state (Dark, dry). The irradiance of light having a wavelength of 340 nm was 0.55 (W / m ² ), and the temperature of the black panel in the irradiation state was 89 ± 3 ° C. The irradiation cycle was repeated 130 cycles. After repeating the irradiation cycle, the hue change (ΔE) before and after irradiation, the gloss retention, and the presence or absence of cracks on the surface of the test piece were evaluated.

(Change in hue before and after irradiation (ΔE))
The hue (L *, a *, b *) of the flat molded product is measured using a color sensor Z-300A (manufactured by Nippon Denshoku Industries Co., Ltd.), and the change in hue (ΔE) is calculated using the following formula: did. A case where ΔE is less than 3.1 is indicated by “◯”, and a case where ΔE is 3.1 or more is indicated by “X”. The results are shown in Tables 3 and 4. In addition, it shows that there are few changes of a hue, so that the value of (DELTA) E is small.
^{_{ΔE = {(L * 1 -L}} * 0) 2 + (a * 1 -a * 0) 2 + (b * 1 -b * 0) 2} 1/2
(L * ₀ , a * ₀ , b * ₀ are initial hues (L *, a *, b *), and L * ₁ , a * ₁ , b * ₁ are hues after irradiation (L *, a * *, B *).)

(Glossiness retention rate (%))
The gloss (measurement angle 60 degrees) of the molded product was measured with a portable gloss meter HG-246 (manufactured by Suga Test Instruments Co., Ltd.), and the gloss retention (%) was calculated using the following formula. A case where the glossiness retention rate was 30% or more was indicated as “◯”, and a case where the glossiness retention rate was less than 30% was indicated as “x”. The results are shown in Tables 3 and 4.
Glossiness retention rate (%) = (initial glossiness) / (glossiness after irradiation) × 100

(Presence of cracks)
The surface of the test piece was visually observed by surface observation with an optical microscope (magnification: 100 times), and the presence or absence of cracks was determined. The case where there was no crack was “◯”, and the case where there was a crack was “x”. The results are shown in Tables 3 and 4.

  (A) 100 parts by weight of a polyacetal copolymer, (B) 0.03 to 0.30 part by weight of a hindered phenol antioxidant, and (C) 0.05 to 0.8 of a guanamine compound and / or a hydrazide compound. And (D) 0.1 to 1.0 part by weight of a hindered amine stabilizer which is a copolymer of an olefin, maleic acid and an amino group-containing piperidine derivative having a weight average molecular weight of 2000 or more, and (E ) Containing 0.1 to 1.0 part by weight of a hindered amine stabilizer having a weight average molecular weight of less than 700 and a nitrogen of the piperidine derivative being tertiary, and (F) 0.2 to 1 part by weight of an ultraviolet absorber. It was confirmed that the polyacetal resin composition produced very little formaldehyde from the resin molded product and was excellent in weather resistance (light) (Examples 1 to 6). Therefore, the polyacetal composition of the present invention can be suitably used as various molded products that require low formaldehyde generation and weather resistance (light) properties, for example, molded products such as building materials and automobile interiors.

  The component of the present invention, the blending amount thereof, and the like can be achieved for the first time based on the following findings found by the study of the present inventor. That is, in general, a hindered amine stabilizer in which the amino group of the piperidine derivative is not modified exhibits better weather resistance (light) than a hindered amine stabilizer in which the amino group is modified, but in the case of a polyacetal resin When a hindered amine stabilizer in which the amino group of the piperidine derivative is not modified is used, the acid component generated with deterioration reacts with the amino group in the hindered amine stabilizer, resulting in insufficient weather resistance. On the other hand, even if it is a hindered amine stabilizer in which the amino group of the piperidine derivative is not modified, the piperidine derivative is a copolymer with an olefin and an amino group-containing maleic acid, so that the reactivity with an acidic substance is low. A hindered amine stabilizer having a good weather resistance (light) resistance in a polyacetal resin produced by an acid component. On the other hand, such specific hindered amine stabilizers have a high molecular weight, but it is experienced that it is more effective to improve weather resistance in combination with a low molecular weight hindered amine stabilizer than to add only a high molecular weight hindered amine stabilizer to the resin. Known. Furthermore, regarding the low molecular weight hindered amine stabilizer used in combination, from the viewpoint of diffusion / bleeding speed, compatibility with the polyacetal resin, and reactivity with the acidic component generated in the polyacetal resin described above, By selecting a hindered amine stabilizer having a piperidine derivative with a tertiary nitrogen of less than 700, a molding material with excellent weather resistance (light) that exhibits stable weather resistance (light) performance over a long period of time can be obtained. Further, by combining with a guanamine compound or a hydrazide compound, the generation of formaldehyde from the molded product can be suppressed to a low level. On the other hand, when these two types of hindered amine stabilizers are used in combination, the blending amount and blending ratio need to be strictly controlled in order to exude blending components and suppress the VOC generation amount other than formaldehyde. The molding material is excellent, and generation of formaldehyde is suppressed, and bleeding and VOC generation other than formaldehyde are also suppressed.

  The polyacetal resin composition of the present invention is composed of a selective combination of a specific polyacetal copolymer and a blending component, and is remarkably produced by formaldehyde by oxidation or thermal decomposition of the polyacetal copolymer in a molding process or the like. It can be suppressed and the working environment can be improved. Moreover, adhesion of decomposition products and additives to the mold (mold deposit) and leaching of decomposition products and additives from the molded product can be remarkably suppressed, and various problems during molding can be improved. For this reason, the resin composition of the present invention can be produced by various methods such as injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotational molding, and gas injection molding. Is useful for molding.

  In addition, the polyacetal resin composition of the present invention is excellent in weather resistance (light) resistance by a selective combination of a specific polyacetal copolymer and a compounding component, and is also used for applications requiring weather resistance (light) resistance. can do.

  The resin composition of the present invention is not limited in the field of use as a molded product, but uses where reduction of the amount of formaldehyde is strongly required, such as automobile parts, electrical / electronic parts, precision machine parts, building materials, piping parts, It can be suitably used for daily necessities, cosmetic parts, medical equipment parts and the like.

Claims (4)

(A) 100 parts by weight of a polyacetal copolymer;
(B) 0.03 to 0.30 parts by weight of a hindered phenol antioxidant,
(C) 0.05 to 0.8 parts by weight of a guanamine compound and / or a hydrazide compound;
(D) a weight average molecular weight of 2000 or more, 0.1 to 1.0 part by weight of a hindered amine stabilizer that is a copolymer of an olefin, maleic acid, and an amino group-containing piperidine derivative;
(E) 0.1 to 1.0 part by weight of a hindered amine stabilizer having a weight average molecular weight of less than 700 and a nitrogen of the piperidine derivative being tertiary;
(F) 0.2-1 part by weight of an ultraviolet absorber;
A polyacetal resin composition containing The component (D) is a copolymer of a C _{20 to} C ₂₄ olefin, maleic anhydride, and 4-amino-2,2,6,6-tetramethylpiperidine.
The component (E) is bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and / or methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate. The polyacetal resin composition according to claim 1.   The polyacetal resin composition according to claim 1 or 2, wherein the component (F) includes at least a benzotriazole ultraviolet absorber or a triazine ultraviolet absorber.   (G) The polyacetal resin composition according to any one of claims 1 to 3, further comprising at least one of a fatty acid ester or a polyalkylene glycol.