JP2007091973A - Polyacetal resin composition and molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide stable polyacetal resin composition that can control the amount of generated formaldehyde to an extremely low level and also causes no adverse effect on other resin molded articles existing together in a tightly closed space. <P>SOLUTION: The polyacetal resin composition includes (B) 0.01 to 5.0 pts.wt. of a carboxylic acid hydrazide based on (A) 100 pts.wt. of a polyacetal resin, wherein (B) the carboxylic acid hydrazide generates less than 10 ppm of hydrazine according to the head space GC/MS method by heating at 200°C for 10 minutes. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stable polyacetal resin composition that suppresses the amount of formaldehyde generated to an extremely low level and does not adversely affect other resin molded articles in a sealed space, and a molded article molded from the resin composition.

  Polyacetal resin is excellent in mechanical properties, fatigue resistance, friction and wear resistance, chemical resistance and moldability, so it can be used for automobile parts, electrical / electronic equipment parts, building materials / piping members, life / cosmetic parts, Widely used in fields such as medical parts. However, with the expansion, diversification, and sophistication of its use, there is a demand for a high-quality polyacetal resin that is more excellent in thermal stability and has an extremely small amount of formaldehyde generated.

  Patent Document 1 discloses a composition comprising a polyacetal copolymer and a specific carboxylic acid hydrazide compound (such as an aliphatic dicarboxylic acid dihydrazide having 3 to 10 carbon atoms, an aromatic dicarboxylic acid dihydrazide, or an alicyclic dicarboxylic acid dihydrazide). ing. When these carboxylic acid hydrazide compounds are used, thermal stability is improved to some extent, and generation of formaldehyde can be suppressed.

However, even if these carboxylic acid hydrazide compounds are used, the effect is not sufficient. In addition, when a molded product made of a polyacetal resin composition containing such a carboxylic acid hydrazide compound is allowed to coexist with another resin molded product, it may adversely affect the characteristics of the other resin molded product. For example, when a molded article made of such a polyacetal resin composition is stored in a high-temperature and high-humidity (eg, 120 ° C., saturated humidity) sealed space in a non-contact state together with a polycarbonate resin molded article, the polycarbonate resin molded article can be obtained in a relatively short time. May corrode.
US Pat. No. 3,152,101 (columns 1 and 3)

  An object of the present invention is to form a stable polyacetal resin composition that suppresses the amount of formaldehyde generated to an extremely low level and does not adversely affect other resin molded products that coexist in a sealed space, and the resin composition. Is to provide a molded product.

  In order to solve the above-mentioned problems, the present inventor conducted a search for a series of carboxylic acid hydrazide compounds with respect to a stabilizer for polyacetal resin. Was found to be able to be suppressed to an extremely low level, and other resin molded products were not adversely affected in the sealed space, and the present invention was completed.

  That is, the present invention comprises 0.01 to 5.0 parts by weight of (B) carboxylic acid hydrazide compound with respect to 100 parts by weight of (A) polyacetal resin, and the carboxylic acid hydrazide compound (B) is heated at 200 ° C. for 10 minutes. Relates to a polyacetal resin composition characterized in that the amount of hydrazine generated is 10 ppm or less in the headspace GC / MS method.

  In the present invention, since the specific carboxylic acid hydrazide compound is added to the polyacetal resin, formaldehyde generated from the molded product of the polyacetal resin composition can be suppressed to an extremely low level. Furthermore, since the molded product of the polyacetal resin composition does not adversely affect other coexisting resin molded products even in a sealed space, stability and reliability can be improved. The effects of the present invention are specific without being impaired by the presence of other additives, and other additives (weather resistance (light) stabilizer, impact resistance improver, slidability improver) , Gloss control agents, fillers, colorants, etc.), the amount of formaldehyde generated from the polyacetal resin composition and its molded product can be suppressed to an extremely low level, and depending on each additive It is also possible to provide a polyacetal resin composition and a molded article having improved various properties (long-term stability, heat resistance, processing characteristics, weather resistance (light) resistance, impact resistance, slidability, etc.).

  The polyacetal resin composition of the present invention comprises a specific carboxylic acid hydrazide compound (B) with respect to the polyacetal resin (A), and the molded product of the present invention is obtained by molding the polyacetal resin composition. It is done. Detailed description will be given below.

The polyacetal resin (A) used in the present invention is a polymer compound having an oxymethylene group (—CH ₂ O—) as a main structural unit, and contains other structural units in addition to the polyacetal homopolymer and the oxymethylene group. Examples include polyacetal copolymers. In addition, all conventionally known polyacetal resins such as those having a branched structure or a crosslinked structure, those having a block structure or a graft structure, and the like are targeted.

  In general, polyacetal homopolymer is produced by polymerization of anhydrous formaldehyde or trioxane, which is a cyclic trimer of formaldehyde. Usually stabilized against thermal degradation by end caps.

  Polyacetal copolymers are generally produced by copolymerizing formaldehyde or formaldehyde cyclic oligomers as main monomers and compounds selected from cyclic ethers or cyclic formals as comonomers. It is stabilized against thermal decomposition by removing the stable part. As the main monomer, trioxane which is a cyclic trimer of formaldehyde is generally used. Trioxane is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst and then purifying it by a method such as distillation. The trioxane used for the polymerization preferably does not substantially contain impurities such as water, methanol and formic acid.

  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, comonomer components capable of forming a branched structure or a crosslinked structure include alkyl glycidyl ethers such as methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, and naphthyl glycidyl ether, ethylene glycol diglycidyl ether, Examples include alkylene such as ethylene glycol diglycidyl ether and butanediol diglycidyl ether, and polyalkylene glycol diglycidyl ether. These comonomers can be used alone or in combination of two or more.
In the present invention, a polyacetal copolymer is particularly preferably used from the viewpoint of suppressing the generation of formaldehyde to a lower level. Among them, trioxane (a-1) and at least one compound (a-2) selected from cyclic ether and cyclic formal are represented by the former (a-1) / the latter (a-2) = 99.9 / 0. A copolymer obtained by copolymerization at a ratio (weight ratio) of 1 to 80.0 / 20.0 is preferable, and a ratio of the former / the latter = 99.5 / 0.5 to 90.0 / 10.0 is more preferable. (Weight ratio) is copolymerized.

  Further, as the compound selected from cyclic ether and cyclic formal, ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal, and diethylene glycol formal are particularly preferable.

  The polyacetal copolymer as described above can be generally obtained by cationic polymerization using a cationic polymerization catalyst with an appropriate amount of molecular weight regulator added. 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 polymerization are well known in many literatures. Basically, any of them can be used.

  The molecular weight of the polyacetal resin used in the present invention is not particularly limited, but those having a weight average molecular weight 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.

  Next, the carboxylic acid hydrazide compound (B) used in the present invention is a carboxylic acid hydrazide compound in which the amount of hydrazine generated is 10 ppm or less by a headspace GC / MS method by heating the sample at 200 ° C. for 10 minutes. The headspace GC / MS method uses a known analyzer, for example, Agilent headspace sampler 7694, mass selective detector 5973, and the sample in the vial is heated at 200 ° C. for 10 minutes, and then the generated gas components Is detected by GC / MS method. The oven temperature on the detection side is maintained at 50 ° C., then the temperature is increased at a rate of temperature increase of 10 ° C./min, GC / MS measurement is performed, and the peak corresponding to hydrazine is assigned. If no detection sensitivity (S / N) is detected, it is determined that hydrazine is substantially not generated.

  The carboxylic acid hydrazide compound (B) used in the present invention has a hydrazine amount of 10 ppm or less generated by decomposition of the carboxylic acid hydrazide compound when heated at 200 ° C. for 10 minutes, which is a general processing condition of the polyacetal resin composition. Need to be. If the amount of hydrazine generated due to decomposition of the carboxylic acid hydrazide compound is more than 10 ppm, hydrazine and / or its reaction components in the polyacetal resin molded product to which the carboxylic acid hydrazide compound is added may adversely affect other resin molded products May affect. As the carboxylic acid hydrazide compound (B) used in the present invention, those which do not substantially generate hydrazine are particularly preferable.

  In order to obtain the carboxylic acid hydrazide compound used in the present invention, for example, (1) a method of heating an ester of a carboxylic acid (such as an alkyl ester) and hydrazine (including hydrazine hydrate), (2) A method of reacting a carboxylic acid halide (such as chloride) with hydrazine, (3) a method of heating carboxylic acid salt and hydrazine, (4) a method of heating acid amide and hydrazine corresponding to carboxylic acid, and (5) It can be produced by a method of reacting ureido of carboxylic acid with hypohalite, etc. At this time, it is purified so that the hydrazine content in the carboxylic acid hydrazide compound to be produced is 100 ppm or less, particularly 10 ppm or less. It is preferable to do.

  The hydrazine content in the compound can be quantified by using a known method such as NMR or chromatography using the compound directly or using an extract of the compound.

  As a specific chemical structure that hardly releases hydrazine by decomposition of the carboxylic acid hydrazide compound by heating at 200 ° C. for 10 minutes, a carboxylic acid hydrazide compound having a chemical structure represented by the following formula (1) is preferable. .

[Wherein, X represents an aromatic ring, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ² represents a hydrogen atom, or an alkyl group or acyl group having 1 to 30 carbon atoms. a represents an integer of 0 to 4, and b represents an integer of 0 to 4. ]
In the formula (1), examples of the aromatic ring represented by X include bisaryl [biphenyl, bisarylalkane (diphenylmethane, 2), in addition to aromatic rings such as a benzene ring, naphthalene ring, anthracene ring, and phenanthrene ring. , 2-diphenylpropane etc.)] and the like. As the aromatic ring X, a benzene ring and a naphthalene ring are particularly preferable.

In the formula (1), R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms and is a substituent bonded to the carbon atom constituting the ring of the aromatic ring X. Examples of the hydrocarbon group represented by R ¹ include an alkyl group (a linear or branched alkyl group such as methyl group, ethyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group), cyclo Examples thereof include an alkyl group (such as a cyclohexyl group) and an aryl group (such as a phenyl group and a naphthyl group).

The number a of R ¹ bonded to the aromatic ring X in the formula (1) can be selected according to the number of the aromatic ring X, and is, for example, an integer of 0 to 6, preferably an integer of 0 to 4, more preferably Is an integer from 0 to 3. For example, when the aromatic ring X is a benzene ring, a is preferably an integer of 0 to 3, particularly preferably an integer of 0 to 2. Further, when the aromatic ring X is a naphthalene ring, a is preferably an integer of 0 to 4, particularly preferably an integer of 0 to 2. When a is 2 or more, R ¹ may be the same or different.

In the formula (1), the group —OR ² is a substituent bonded to the carbon atom constituting the ring of the aromatic ring X. The group —OR ² includes a hydroxyl group in which R ² is hydrogen and a derivative group of the hydroxyl group [an alkoxy group having 1 to 30 carbon atoms such as a methoxy group (that is, R ² is an alkyl group such as a methyl group), an acetyl group Etc.], and the like.

The number b of the group —OR ² bonded to the aromatic ring X in the formula (1) is, for example, an integer of 0 to 4, preferably an integer of 0 to 3, more preferably, depending on the number of the aromatic ring X. Is an integer of 0-2. For example, when the aromatic ring X is a benzene ring, b is preferably an integer of 0 to 3, and particularly preferably an integer of 0 to 2. Moreover, when the aromatic ring X is a naphthalene ring, b is preferably an integer of 0 to 4, particularly preferably an integer of 0 to 2. When b is 2 or more, the groups -OR ² may be the same or different.

  In the carboxylic acid hydrazide compound (B) used in the present invention, examples of the carboxylic acid and its derivatives used as intermediate raw materials include benzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, 2-ethyl. Benzoic acid, 3-ethylbenzoic acid, 4-ethylbenzoic acid, 4-isopropylbenzoic acid, 4-n-propylbenzoic acid, 2,3,4,5-tetramethylbenzoic acid, pentamethylbenzoic acid, 2,3- Dimethylbenzoic acid, 2,4-dimethylbenzoic acid, 2,5-dimethylbenzoic acid, 2,6-dimethylbenzoic acid, 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, 2,3,4- Trimethylbenzoic acid, 2,3,5-trimethylbenzoic acid, 2,3,6-trimethylbenzoic acid, 2,4,5-trimethylbenzoic acid, 2,4,6-trimethylbenzoic acid, , 4,5-trimethylbenzoic acid, 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, 2,3,4-trihydroxybenzoic acid, 2,4 , 5-trihydroxybenzoic acid, 2,4,6-trihydroxybenzoic acid, 3-methylsalicylic acid, 4-methylsalicylic acid, 5-methylsalicylic acid, 3-hydroxy-2-methylbenzoic acid, 2-hydroxy-3,5- Dimethylbenzoic acid, 3-hydroxy-4-isopropylbenzoic acid, 2-hydroxy-3-isopropyl-6-methylbenzoic acid 4,6-dihydroxy-2-methylbenzoic acid, 2,6-dihydroxy-4-methylbenzoic acid, 3,5-di-t-butyl-4-hydroxybenzoic acid, 3-methyl-5-t-butyl-4 -Benzoic acid-based compounds such as hydroxybenzoic acid, oreseric acid, divaric acid, olivetol carboxylic acid, spheroholol carboxylic acid, methyloryselic acid, 4-hydroxyorceric acid, 6-hydroxyorceric acid, 1- Naphthoic acid, 2-naphthoic acid, 2-methyl-1-naphthoic acid, 4-methyl-1-naphthoic acid, 5-methyl-1-naphthoic acid, 6-methyl-1-naphthoic acid, 7-methyl-1-naphthoic acid, 8- Methyl-1-naphthoic acid, 1-methyl-2-naphthoic acid, 4-methyl-2-naphthoic acid, 5-methyl-2-naphthoic acid, 6-methyl-2-naphtho Ethic acid, 8-methyl-2-naphthoic acid, 2-hydroxy-1-naphthoic acid, 4-hydroxy-1-naphthoic acid, 5-hydroxy-1-naphthoic acid, 7-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid , Naphthoic acid compounds such as 3-hydroxy-2-naphthoic acid, 6-hydroxy-2-naphthoic acid, anthracene-1-carboxylic acid, anthracene-2-carboxylic acid, anthracene-9-carboxylic acid, 2-methyl-1-anthracenecarboxylic acid 4-methyl-1-anthracenecarboxylic acid, 4-phenyl-1-anthracenecarboxylic acid, 9-phenyl-1-anthracenecarboxylic acid, 10-phenyl-9-anthracenecarboxylic acid, 3-benzyl-2-anthracenecarboxylic acid, 2-methyl-9 -Phenyl-1-anthracene Anthracene carboxylic acid compounds such as rubonic acid, 3-methyl-9-phenyl-1-anthracene carboxylic acid, phenanthrene-1-carboxylic acid, phenanthrene-2-carboxylic acid, phenanthrene-3-carboxylic acid, phenanthrene-9-carboxylic acid 9,10-dihydroxy-9-phenanthrenecarboxylic acid, 1-methyl-3-phenanthrenecarboxylic acid, 5-methyl-9-phenanthrenecarboxylic acid, 6-ethyl-9-phenanthrenecarboxylic acid, 6,8-dimethyl-9-phenanthrenecarboxylic acid Carboxylic acid and derivatives thereof, such as bisaryl compounds such as 4'-hydroxybiphenyl-4-carboxylic acid.

Among the carboxylic acid hydrazide compounds (B) used in the present invention, as a particularly preferred chemical structure, in the formula (1), the aromatic ring X is a naphthalene ring, and R ¹ is a linear or branched alkyl group. Yes, a is an integer of 0-2, and b is an integer of 0-2.

  The carboxylic acid hydrazide compounds of the present invention can be used alone or in combination of two or more. The ratio of these carboxylic acid hydrazide compounds (B) is 0.01 to 5.0 parts by weight, preferably 0.02 to 3.0 parts by weight, and more preferably 0.8 to 100 parts by weight of the polyacetal resin. 03 to 2.0 parts by weight. If the proportion of the carboxylic acid hydrazide compound (B) is too small, it is difficult to effectively reduce the amount of formaldehyde generated, and if it is too large, the moldability and mechanical strength are lowered.

  The polyacetal resin composition of the present invention significantly reduces the amount of formaldehyde generated from the resin composition and its molded product by using such a specific carboxylic acid hydrazide compound. Since the resin molded product is not adversely affected, the stability and reliability of the polyacetal resin composition can be improved.

  The polyacetal resin composition of the present invention further includes (C) an antioxidant, (D) a heat stabilizer, (E) a workability improver, (F) a weather (light) stabilizer, or an impact improver. By blending at least one selected from a slidability improver, a gloss control agent, a filler and a colorant, various properties corresponding to the respective additives are improved without impairing the object of the present invention. be able to.

Details of these additives are as follows.
(C) Antioxidant In the polyacetal resin composition of the present invention, an antioxidant is used in order to maintain the short-term and long-term characteristics by suppressing the oxidative degradation of the resin and to suppress the generation of formaldehyde accompanying the degradation. It is preferable to mix.

  Antioxidants include hindered phenol compounds, hindered amine compounds, phosphorus compounds, sulfur compounds, hydroquinone compounds, quinoline compounds, and the like. These antioxidants can be used alone or in combination of two or more. Of these, hindered phenol compounds and hindered amine compounds are preferable, and hindered phenol compounds are particularly preferable.

  Examples of the hindered phenol compound include a monocyclic hindered phenol compound such as 2,6-di-t-butyl-p-cresol; a polycyclic hinder linked with a hydrocarbon group or a group containing a sulfur atom. Dophenol compounds such as 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-methylenebis (2,6-di-tert-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), etc .; ester group or amide Hindered phenol compounds having, for example, n-octadecyl-3- (4'-hydroxy-3 ', 5'-di-t-butylphenyl) propionate, n-octadecyl-2- (4'-hydroxy-3' , 5'-di-t-butylphenyl) propionate, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethyl ester -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-pentylphenyl) 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-tert-butyl-4-hydroxyphenyl) propionamide], N, N'-tetramethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide Mido], N, N′-hexamethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide], N, N′-ethylenebis [3- (3-t-butyl) -5-methyl-4-hydroxyphenyl) propionamide], N, N'-hexamethylenebis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionamide], N, N'- Bis [3- (3,5-di-tert-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-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6) - Chirubenjiru) isocyanurate and the like.

  Examples of the hindered amine compound include ester group-containing piperidine derivatives such as 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4- Acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) oxalate Bis (2,2,6,6-tetramethyl-4-piperidyl) malonate, bis (2,2,6,6-tetramethyl-4-piperidyl) adipate, bis (1,2,2,6,6) -Pentamethyl-4-piperidyl) adipate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2 6,6-pentamethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) terephthalate, tris (2,2,6,6-tetramethyl-4-piperidyl) benzene 1,3,5-tricarboxylate and the like; ether group-containing piperidine derivatives such as 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethyl Piperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6,6-tetramethylpiperidine, 1,2-bis (2,2,6,6-tetra Methyl-4-piperidyloxy) ethane and the like; amide group-containing piperidine derivatives such as [4- (phenylcarbamoyloxy) -2,2,6,6 Tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylene-1,6-dicarbamate, and the like. High molecular weight piperidine derivative polycondensates are also included.

These antioxidants (C) can be used alone or in combination of two or more. The blending ratio when blending the antioxidant (C) is preferably 0.01 to 5.0 parts by weight, more preferably 0.02 to 3.0 parts by weight, particularly preferably 100 parts by weight of the polyacetal resin. Is 0.03 to 2.0 parts by weight.
(D) Heat-resistant stabilizer The polyacetal resin composition of the present invention retains various properties of the resin by suppressing the thermal decomposition of the resin during extrusion and molding, and generates formaldehyde associated with the decomposition of the resin. In order to suppress it, it is preferable to mix a heat stabilizer.

  Examples of heat stabilizers include organic carboxylic acid metal salts, basic nitrogen-containing compounds, alkali or alkaline earth metal compounds, hydrotalcite, zeolite, and phosphine compounds.

  Examples of the metal forming the organic carboxylic acid metal salt include alkali metals such as Li, Na, and K, alkaline earth metals such as Mg and Ca, and transition metals such as Zn. 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, and saturated aliphatic monocarboxylic acid, saturated aliphatic dicarboxylic acid, Examples thereof include saturated aliphatic monocarboxylic acids, unsaturated aliphatic dicarboxylic acids, and oxyacids thereof. These aliphatic carboxylic acids may have a hydroxyl group. The organic carboxylic acid forming the organic carboxylic acid metal salt is a copolymer of a polymerizable unsaturated carboxylic acid (such as (meth) acrylic acid, maleic acid, fumaric acid, maleic anhydride, monoethyl maleate) and an olefin. It may be. Specific examples of such organic carboxylic acids 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 citrate, calcium citrate, calcium stearate, magnesium stearate, magnesium 12-hydroxystearate, and calcium 12-hydroxystearate, and ionomer resins. Among these organic carboxylic acid metal salts, alkaline earth metal salts such as calcium citrate, magnesium stearate, calcium stearate, 12-hydroxymagnesium stearate, and 12-hydroxycalcium stearate are preferable from the viewpoint of stabilizing effect.

  Examples of the basic nitrogen-containing compound include aminotriazine compounds, guanidine compounds, urea compounds, amino acid compounds, amino alcohol compounds, imide compounds, amide compounds, and hydrazine compounds.

  Examples of the aminotriazine compound include melamine or a derivative thereof, guanamine or a derivative thereof, and an aminotriazine resin. Examples of melamine derivatives include melam and melem, and examples of guanamine derivatives include alkyl-substituted guanamines such as acetoguanamine and stealoganamin, alkylene-bisguanamines such as adipodiguanamine, and alicyclic guanamines such as cyclohexanecarboguanamine. , Aromatic guanamines such as benzoguanamine, phenylbenzoguanamine and hydroxybenzoguanamine, polyguanamines such as phthaloguanamine and naphthalenediguanamine, and heteroatom-containing guanamines such as CTU-guanamine and CMTU-guanamine, etc. Melamine-formaldehyde resin, melamine-phenol-formaldehyde resin, benzoguanamine-formaldehyde resin, benzoguanamine-phenol An example of the formaldehyde-formaldehyde resin. Melamine derivatives and guanamine derivatives include compounds in which the amino group hydrogen is substituted with a methylol group or an alkoxymethyl group (for example, mono-hexamethylol melamine, mono-hexamethoxymethyl melamine, mono-tetramethoxymethyl benzoguanamine, etc. ) Is also included.

  Guanidine compounds include acyclic guanidine (glycosamine, guanolin, guanidine, cyanoguanidine, etc.), cyclic guanidine (glycocyanidin, creatinine, oxalylguanidine, 2,4-diiminoparabanic acid, etc.), imino group-substituted urazole compounds (iminourasol). , Guanazine, etc.), isocyanuric imides (isoammelide, isoammelin, etc.), malonyl guanidine, tartronyl guanidine, mesoxalyl guanidine, and the like.

  Examples of urea compounds include non-cyclic urea compounds (N-substituted urea substituted with a substituent such as urea or an alkyl group, acyclic urea condensates (biuret, biurea, methylene diurea, form nitrogen, etc.)), cyclic urea, etc. Compound [alkylene urea, arylene urea, ureido of dicarboxylic acid, ureido of β-aldehyde acid, ureido of α-oxyacid (hydantoin, 5-methylhydantoin, 5-phenylhydantoin, 5-benzylhydantoin, 5,5-dimethylhydantoin 5-methyl-5-phenylhydantoin, 5,5-diphenylhydantoin, 5,5-dibenzylhydantoin, pentamethylenebishydantoin, allantoin or metal salts thereof), uric acid, alkyl-substituted uric acid, acetylene urea (glycoluril) Or its derivatives, clotylide And diurea of α-oxyacid, diurea, diureide of dicarboxylic acid, etc.].

  Examples of amino acid compounds include α-amino acids, β-amino acids, γ-amino acids, and δ-amino acids. The amino acid compound may be any of D-form, L-form, and DL-form, and further includes amino acid derivatives in which a carboxyl group is metallated, amidated, hydrazated, or esterified.

  Amino alcohol compounds include monoethanolamine, diethanolamine, 2-amino-1-butanol, 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino Examples include aminoaliphatic mono- or polyols such as 2-ethyl-1,3-propanediol and tris (hydroxymethyl) aminomethane.

  As the imide compound, aromatic polycarboxylic imides such as phthalic imide, trimellitic imide, and pyromellitic imide can be used.

  Examples of the amide compound include aliphatic carboxylic acid amides, cyclic carboxylic acid amides, aromatic carboxylic acid amides, polyamide resins [for example, polyamide 3, polyamide 46, polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide MXD6. , Polyamide 6-10, polyamide 6-11, polyamide 6-12, polyamide 6-66-610, polyamide 9T, etc.], polyesteramide, polyamideimide, polyurethane, poly (meth) acrylic acid amide homopolymer or copolymer, poly (Vinyl lactam) homopolymer or copolymer, poly (N-vinylcarboxylic acid amide), copolymers of N-vinylcarboxylic acid amide and other vinyl monomers, and the like can be mentioned.

  Hydrazine compounds include aliphatic or alicyclic carboxylic acid hydrazides (saturated or unsaturated fatty acid hydrazides such as lauric acid hydrazide, stearic acid hydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, sorbic acid hydrazide, α- Oxy fatty acid hydrazides such as oxybutyric acid hydrazide and glyceric acid hydrazide), aromatic carboxylic acid hydrazides (phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide and the like).

Examples of the alkali or alkaline earth metal compound include metal oxides (CaO, MgO, etc.), metal hydroxides (LiOH, Ca (OH) ₂ , Mg (OH) ₂ etc.), metal inorganic acid salts (Li ₂ CO _3). , Na ₂ CO ₃ , K ₂ CO ₃ , CaCO ₃ , MgCO ₃ and other metal carbonates, borates, phosphates, etc.), and in particular, alkaline earth metal oxides and hydroxides preferable.

  As the hydrotalcite, for example, a hydrotalcite compound represented by the following formula can be used.

^{_{[M 2+ 1-X M 3+}} X (OH) 2] X + [A n- X / n · mH 2 O] X-
^(.A shown ^{wherein, M 2+} is ^{Mg 2+, Mn 2+, Fe 2+} , a divalent metal ion such as ^{Co 2+, M 3+} is ^{Al 3+,} Fe ^3+, trivalent metal ions such as ^{Cr 3+ n-} Represents an anion of n valence (especially monovalent or divalent) such as CO ₃ ²⁻ , OH ⁻ , HPO ₄ ²⁻ , SO ₄ ²⁻ , x is 0 <x <0.5, and m is , 0 ≦ m <1)
As the zeolite, zeolite whose minimum unit cell is a crystalline aluminosilicate of alkali and / or alkaline earth metal, for example, A type, X type, Y type, L type, ZSM type zeolite, chabazite, mordenite, Natural zeolite such as faujasite can be used.

  Examples of phosphine compounds include alkyl phosphines (such as triethylphosphine, tripropylphosphine, and tributylphosphine), cycloalkylphosphines (such as tricyclohexylphosphine), and arylphosphines (such as triphenylphosphine, p-tolyldiphenylphosphine, and di-p-). Tolylphenylphosphine, tri-m-aminophenylphosphine, tri (2,4-dimethylphenyl) phosphine, tri (2,4,6-trimethylphenyl) phosphine, tri (o-, m- or p-tolyl) phosphine, etc. ), Aralkylphosphines (such as tri (o-, m- or p-anisyl) phosphine), arylalkenylphosphines (such as diphenylvinylphosphine and allyldiphenylphosphine), arylaralkylphosphines Such as p-anisyldiphenylphosphine, di (p-anisyl) phenylphosphine, methylphenyl-p-anisylphosphine, and bisphosphines (such as 1,4-bis (diphenylphosphino) butane). Examples include phosphine compounds.

The blending ratio when the heat stabilizer is blended is preferably 0.01 to 5.0 parts by weight, more preferably 0.02 to 3.0 parts by weight, and particularly preferably 0.0 to 3.0 parts by weight with respect to 100 parts by weight of the polyacetal resin. 03 to 2.0 parts by weight.
(E) Processability improver The polyacetal resin composition of the present invention has good resin properties, particularly dimensional accuracy and surface properties of molded products, by improving processability during extrusion and molding. It is preferable to add a processability improver in order to suppress the decomposition of the resin due to shearing during extrusion or molding and the accompanying generation of formaldehyde.

  Such processability improvers include long chain fatty acids or derivatives thereof, polyalkylene glycols, silicone compounds, various waxes and the like.

  Examples of such long-chain fatty acids include monovalent saturated or unsaturated fatty acids having 10 or more carbon atoms (for example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid, oleic acid, linoleic acid, Erucic acid and the like) and divalent saturated or unsaturated fatty acids having 10 or more carbon atoms (for example, sebacic acid, dodecanedioic acid, tetradecanedioic acid, dodecenedioic acid, etc.). Long-chain fatty acids also include fatty acids (such as 12-hydroxystearic acid) in which some hydrogen atoms are substituted with substituents such as hydroxyl groups.

  Derivatives of long chain fatty acids include fatty acid esters and fatty acid amides. The alcohol constituting the long-chain fatty acid ester may be either a monohydric alcohol or a polyhydric alcohol, but an ester with a polyhydric alcohol is often preferred.

  Examples of esters of long chain fatty acids and monohydric alcohols include stearyl stearate and stearyl palmitate.

  Examples of esters of long-chain fatty acids and polyhydric alcohols include ethylene glycol mono or dipalmitate, ethylene glycol mono or distearate, ethylene glycol mono or dibehenate, ethylene glycol mono or dimanthate, Glycerol mono-tripalmitic acid ester, glycerin mono-tristearic acid ester, glycerin mono-tribehenic acid ester, glycerin mono-trimontanic acid ester, pentaerythritol mono-tetrapalmitic acid ester, pentaerythritol mono-tetrastearic acid ester, pentaerythritol Mono to tetrabehenate, pentaerythritol mono to tetramontanate, polyglycerol tristeary Acid esters, trimethylolpropane monopalmitate, pentaerythritol monoundecylate, sorbitan monostearate, polyalkylene glycol (polyethylene glycol, polypropylene glycol, etc.) mono or dilaurate, mono or dipalmitate, mono or distearate, mono Or dibehenate, mono or dimontanate, mono or diolate, mono or dilinoleate, etc. are mentioned.

  As fatty acid amides, primary fatty acid amides such as capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and montanic acid amide, and unsaturated acids such as oleic acid amide Fatty acid primary acid amide, stearyl stearic acid amide, stearyl oleic acid amide and other saturated and / or unsaturated fatty acid and monoamine secondary acid amide, 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. It is below. Further, bisamide having a structure in which different acyl groups are bonded to the amine moiety of alkylenediamine such as ethylenediamine- (stearic acid amide) oleic acid amide can also be used. Of these fatty acid amides, bisamide compounds are particularly preferred.

  Examples of the polyalkylene glycol include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, polyoxyethylene-polyoxypropylene copolymers (random or block copolymers, etc.), polyoxyethylene polyoxypropylene glyceryl. Examples thereof include copolymers such as ether and polyoxyethylene polyoxypropylene monobutyl ether. Of these, polymers having oxyethylene units, such as polyethylene glycol, polyoxyethylene polyoxypropylene copolymers, and derivatives thereof are preferable.

  The silicone compound includes organosiloxane and polyorganosiloxane. Examples of the organosiloxane include dimethylsiloxane, phenylmethylsiloxane, and diphenylsiloxane. Examples of the polyorganosiloxane include homopolymers (polydimethylsiloxane, polyphenylmethylsiloxane, etc.) and copolymers of the organosiloxane. . The polyorganosiloxane may be an oligomer. Organosiloxanes and polyorganosiloxanes include epoxy groups, hydroxyl groups, alkoxy groups, carboxyl groups, amino groups or substituted amino groups (such as dialkylamino groups), ether groups, vinyl groups, ) Modified products having a substituent such as an acryloyl group are also included.

  Examples of the wax include low molecular weight polyolefin (for example, low molecular weight polyethylene, low molecular weight copolymer of ethylene and α-olefin), oxidized polyethylene wax and the like.

The proportion when blending these processability improvers is preferably 0.01 to 5.0 parts by weight, more preferably 0.02 to 3.0 parts by weight, particularly preferably 100 parts by weight of the polyacetal resin. 0.03 to 2.0 parts by weight.
(F) Weather resistance (light) stabilizer The polyacetal resin composition of the present invention may further contain a weather resistance (light) stabilizer in order to impart weather resistance (light) resistance. Even if it mix | blends, the inhibitory effect of formaldehyde generation | occurrence | production by a specific hydrazide derivative (B) is not impaired.

  Weather resistance (light) stabilizers include benzotriazole compounds, benzophenone compounds, aromatic benzoate compounds, cyanoacrylate compounds, oxalic acid anilide compounds, hydroxyaryl-1,3,5-triazine compounds, hindered amine compounds Compound etc. are mentioned.

  Examples of the benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di (t-butyl) phenyl) benzotriazole, 2 -(2'-hydroxy-3 ', 5'-di (t-amyl) phenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-diisoamylphenyl) benzotriazole, 2- [2 ' -Hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] benzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole and the like.

  Examples of the benzophenone compounds include benzophenones having a plurality of hydroxyl groups (such as 2,4-dihydroxybenzophenone and 2-hydroxy-4-oxybenzylbenzophenone), and benzophenones having a hydroxyl group and an alkoxy group (2-hydroxy-4- Methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, etc.).

  Examples of the aromatic benzoate compounds include alkylaryl salicylates such as pt-butylphenyl salicylate and p-octylphenyl salicylate.

  Examples of the cyanoacrylate compounds include cyano group-containing diaryl acrylates such as 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate and ethyl-2-cyano-3,3-diphenyl acrylate.

  Examples of the oxalic acid anilide compounds include N- (2-ethylphenyl) -N ′-(2-ethoxy-5-t-butylphenyl) oxalic acid diamide, N- (2-ethylphenyl) -N ′-(2 Examples include oxalic acid diamides having an aryl group substituted on a nitrogen atom, such as -ethoxy-phenyl) oxalic acid diamide.

  Examples of hydroxyaryl-1,3,5-triazine compounds include 2,4-diphenyl-6- (2-hydroxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2,4 -Dihydroxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2 -Hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- 6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-to Azine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl)- 1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4-di (p-tolyl or 2 ', 4 '-Dimethylphenyl) -6- (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4- (2-butoxyethoxy) phenyl ) -1,3,5-triazine, 2,4-di-p-tolyl-6- (2-hydroxy-4- (2-hexyloxyethoxy) phenyl) -1,3,5-triazine and the like. .

  As the hindered amine compound, the hindered amine compounds exemplified in the section of the antioxidant can be used.

  These weather resistance (light) stabilizers may be used alone, or two or more of the same or different weather resistance (light) stabilizers may be used in combination. In particular, it is preferable to use a benzotriazole compound and a hindered amine compound in combination. When both are used in combination, the ratio (weight ratio) of both is benzotriazole compound / hindered amine compound = 99.5 / 0.5. It is preferable to set it to -0.5 / 99.5, More preferably, it is 90 / 10-30 / 70, Especially preferably, it is 80 / 20-40 / 60.

In the present invention, the blending ratio when the weathering (light) stabilizer is blended is preferably 0.01 to 5.0 parts by weight, more preferably 0.05 to 3.0 parts by weight with respect to 100 parts by weight of the polyacetal resin. Particularly preferred is 0.1 to 2.0 parts by weight.
(Other additives)
The polyacetal resin composition of the present invention further contains one or more additives selected from impact resistance improvers, slidability improvers, gloss control agents, fillers, colorants, and the like. May be.

  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. . When blending the impact modifier, the proportion is preferably 0.1 to 50 parts by weight, more preferably 1 to 30 parts by weight, and even more preferably 3 to 20 parts by weight with respect to 100 parts by weight of the polyacetal resin. .

  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 resins ( And silicone compounds exemplified in the section of the processability improver), fluorine resins (polytetrafluoroethylene and the like), fatty acid esters and the like. These slidability improvers can be used alone or in combination of two or more. The proportion in the case of blending the slidability improver is preferably 0.01 to 20 parts by weight, more preferably 0.03 to 10 parts by weight, still more preferably 0.05 to 5 parts per 100 parts by weight of the polyacetal resin. Parts by weight.

  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.), olefin resin (polypropylene, cyclic polyolefin, etc.) and the like. When blending the gloss control agent, the blending ratio is preferably 0.1 to 30 parts by weight, more preferably 0.2 to 20 parts by weight, and still more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the polyacetal resin. Part.

  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. When blending the filler, the blending ratio is preferably 0.1 to 150 parts by weight, more preferably 0.5 to 100 parts by weight, and further preferably 1 to 80 parts by weight with respect to 100 parts by weight of the polyacetal resin. .

  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 pigment include azo pigments, anthraquinone pigments, phthalocyanine pigments, quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, dioxazine pigments, and selenium pigments. Etc. can be exemplified. 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 blending ratio in the case of blending the colorant is preferably 0.01 to 5 parts by weight, more preferably 0.02 to 3 parts by weight, still more preferably 0.03 to 2 parts by weight with respect to 100 parts by weight of the polyacetal resin. It is.

If necessary, the polyacetal resin composition of the present invention may contain other conventional additives such as mold release agents, nucleating agents, antistatic agents, flame retardants, foaming agents, surfactants, antibacterial agents, antifungal agents. Agents, fragrances, fragrances and the like may be included.
(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 Supplying the remaining components from the main feed port of the extruder through the side feed port and melt-kneading them to obtain a pellet-shaped composition. (3) Preparing pellets having different compositions by extrusion or the like, and mixing the pellets (4) Mixing a predetermined amount of a blending component into a pellet or pulverized product of a polyacetal resin, or coating a predetermined amount of a blending component on the surface of a pellet or pulverized product of a polyacetal resin A method for obtaining 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 step together with water and low-boiling point alcohols from the devolatilization vent port. Thereby, the amount of formaldehyde generated from the polyacetal resin composition and its molded product can be further reduced. Further, when the hydrazone compound is side-fed, it is preferably fed after the devolatilization vent port.
(Molding)
The molded product formed with the said resin composition is also contained in this invention. In the polyacetal molded article of the present invention, the amount of formaldehyde generated is greatly suppressed by incorporating a specific carboxylic acid hydrazide compound. Specifically, under wet conditions, the amount of formaldehyde generated is 2 μg / g or less, preferably 1 μg / g or less per unit weight of the molded product. Further, under dry conditions, the amount of formaldehyde generated is 2 μg / g or less, preferably 1 μg / g or less per unit weight of the molded product. The amount of formaldehyde generated under wet and dry conditions is (1) the amount of formaldehyde generated when a molded product having a thickness of 2 mm is stored in a sealed space of saturated humidity at a temperature of 60 ° C. for 3 hours, and (2) a temperature of 80 It is the amount of formaldehyde generated when a molded product having a thickness of 2 mm is stored for 24 hours in a sealed space at 0 ° C., and more specifically, by the measurement method described in the Examples section.

  In addition, the polyacetal resin molded product of the present invention can be held under severe conditions (for example, a high temperature and high humidity sealed space) by coexisting with a molded product made of a resin other than polyacetal resin such as polycarbonate resin and polyester resin. The molded product made of another resin can be used stably without being substantially corroded. The corrosiveness to other resins can be evaluated by the method described in the Examples section.

  The polyacetal resin composition of the present invention can be molded by various known molding methods (for example, injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotational molding, gas injection molding, etc.). Useful for molding articles.

  The resin composition of the present invention is not limited in the field of use as a molded product, but uses where reduction of formaldehyde generation 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.

  EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

In addition, the evaluation item and its measuring method in an Example and a comparative example are as follows.
[Hydrazine generation in headspace GC / MS measurement]
Using an Agilent headspace sampler 7694 and mass selective detector 5973, sample 0.02 g of carboxylic acid hydrazide compound into a 20 ml vial and take measures to prevent inhalation with baked quartz wool. The sample was heated at 200 ° C. for 10 minutes, and the generated gas components were measured by GC / MS. The oven temperature on the detection side was kept at 50 ° C. for 4 minutes, and then heated at a rate of temperature increase of 10 ° C./min and subjected to GC / MS measurement, and assignment and quantification of the peak corresponding to hydrazine were performed. When no detection sensitivity (S / N) was detected, it was determined that hydrazine was substantially not generated. 1 and 2 show examples of measurement results (GC chart).
[Formaldehyde generation from wet molded products]
Using the polyacetal resin compositions prepared in Examples and Comparative Examples, flat plate test pieces (100 mm × 40 mm × 2 mm) were molded by injection molding (molding temperature 190 ° C.). Two flat test pieces (total weight of about 22 g) were hung on the lid of a polyethylene bottle (capacity: 1 L) containing 50 ml of distilled water and sealed, and left in a thermostatic bath at a temperature of 60 ° C. for 3 hours. Then, it left still 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 quantified according to JIS K0102, 29 (formaldehyde term), and the amount of formaldehyde generated per unit weight (μg / g) was determined. Calculated.
[Formaldehyde generation amount from dry molded products]
Using the polyacetal resin compositions prepared in Examples and Comparative Examples, prismatic test pieces (2 mm × 2 mm × 50 mm) were molded by injection molding (molding temperature 190 ° C.). Ten prismatic test pieces (total weight of about 2.7 g) are put in a 20 ml container, sealed, heated in a thermostat at 80 ° C. for 24 hours, and then taken out from the thermostat to room temperature. Air-cooled until. Next, 5 ml of distilled water was injected into the container with a syringe, and formaldehyde generated from the test piece was absorbed into the distilled water. The amount of formaldehyde in this aqueous solution was quantified according to JIS K0102, 29 (formaldehyde term), and the amount of formaldehyde generated (μg / g) per unit weight of the test piece was calculated.
[Polycarbonate resin molded product corrosion test]
Polyacetal resin molded product (the number of the prismatic test pieces cut into 2 mm length is the total number of 1.5 g) and water (0.1 ml) are put in a sealed container (capacity 20 ml) and baked out on it. The polyacetal resin molded product and the polycarbonate resin molded product were placed in a non-contact state by placing the used quartz wool and further placing a polycarbonate resin molded product (disc fragment) on the quartz wool. Subsequently, the container was held in a sealed space at a temperature of 120 ° C./saturated humidity, the occurrence of corrosion of the polycarbonate resin molded product was visually observed, and the time when the corrosion occurred was measured. The test was conducted for up to 200 hours. If no corrosion was observed at this point, it was determined that there was no corrosion.

This corrosion test can also be applied to the corrosive evaluation of other resin molded products by using molded products of other resins instead of polycarbonate resin molded products.
Examples 1-13
After mixing a carboxylic acid hydrazide compound, an antioxidant, a heat stabilizer, and a processability improver in 100 parts by weight of a polyacetal resin in the ratios shown in Tables 1 and 2, 30 mm diameter twin screw extrusion having one vent port A pellet-shaped composition was prepared by feeding to a main feed port of a machine (cylinder temperature 200 ° C.), melt-kneading and extruding. Predetermined test pieces were injection molded using the obtained pellet-shaped composition, and the formaldehyde generation amount and the polycarbonate resin molded product corrosion test were evaluated by the above evaluation methods. Further, the amount of hydrazine generated from the carboxylic acid hydrazide compound used for the preparation of the composition was measured by the headspace GC / MS measurement method. These results are shown in Tables 1-2.
Comparative Examples 1-14
For comparison, an example in which no carboxylic acid hydrazide compound was added and an example in which a carboxylic acid hydrazide compound that did not satisfy the requirements defined in the present invention was added were evaluated in the same manner as described above. The results are shown in Tables 1-2.

The polyacetal resins, carboxylic acid hydrazide compounds, antioxidants, heat stabilizers, and processability improvers used in Examples and Comparative Examples are as follows. The hydrazine content in the carboxylic acid hydrazide compound was measured by proton NMR (400 MHz, 30 ° C., total 384 times) using DMSO-d6 as a solvent. A compound without a hydrazine content indicates that hydrazine is not detected in NMR detection sensitivity (S / N).
A. Polyacetal resin (a-1): Polyacetal resin copolymer (copolymer of trioxane and 1,3-dioxolane, 3.8% by weight copolymerization of 1,3-dioxolane, melt index = 9 g / 10 min)
In addition, the said melt index is the value calculated | required on the conditions of 190 degreeC and a load of 2.16 kg according to ASTM-D1238.
B. Carboxylic acid hydrazide compound Carboxylic acid hydrazide compound (b-1): 1-naphthoic acid hydrazide (b-2): 2-naphthoic acid hydrazide corresponding to the definition of the present invention (b) -3): adipic acid dihydrazide (b-4): tris (hydrazinocarbonylethyl) isocyanurate (b-5): adipic acid dihydrazide (containing hydrazine 2000 ppm)
(B-6): Tris (hydrazinocarbonylethyl) isocyanurate (containing hydrazine 3000 ppm)
(B-7): 2-naphthoic acid hydrazide (containing 2000 ppm of hydrazine)
C. Antioxidant (c-1): Triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate]
(C-2): Pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]
D. Heat stabilizer (d-1): calcium stearate (d-2): 12-hydroxycalcium stearate (d-3): calcium citrate Processing stabilizer (e-1): ethylenebisstearylamide (e-2): polyethylene oxide [molecular weight: 35000].
(E-3): Montanate ester [Toyo Petrolite Co., Ltd., LUZAWAX-EP]

  As is apparent from the table, the polyacetal resin compositions of the examples have a much smaller amount of formaldehyde than the comparative examples, and the molded product stored in the sealed space is a non-contact polycarbonate resin in the sealed space. The molded product does not substantially corrode, and has high quality and high reliability.

The GC chart of the carboxylic acid hydrazide compound b-3 used for the resin composition of the comparative examples 2 and 10 is shown. The GC chart of carboxylic acid hydrazide compound b-6 used for the resin composition of comparative examples 5 and 13 is shown.

Claims (10)

  (A) 0.01 to 5.0 parts by weight of (B) carboxylic acid hydrazide compound per 100 parts by weight of polyacetal resin, and the carboxylic acid hydrazide compound (B) is a headspace GC / MS by heating at 200 ° C. for 10 minutes. A polyacetal resin composition characterized in that the amount of hydrazine generated in the method is 10 ppm or less.   The polyacetal resin composition according to claim 1, wherein the hydrazine content of the carboxylic acid hydrazide compound (B) is 10 ppm or less. The polyacetal resin composition according to claim 1 or 2, wherein the carboxylic acid hydrazide compound (B) is at least one selected from carboxylic acid hydrazide compounds represented by the following general formula (1).

[Wherein, X represents an aromatic ring, R ¹ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ² represents a hydrogen atom, or an alkyl group or acyl group having 1 to 30 carbon atoms. a represents an integer of 0 to 4, and b represents an integer of 0 to 4. ]   The carboxylic acid hydrazide compound (B) is represented by the general formula (1) wherein X is a naphthalene ring, a is an integer of 0-2, and b is an integer of 0-2. The polyacetal resin composition according to 1.   The polyacetal resin composition according to any one of claims 1 to 4, wherein the polyacetal resin (A) is a polyacetal copolymer.   When the polyacetal resin (A) is trioxane (a-1) and at least one compound (a-2) selected from cyclic ether and cyclic formal, the former (a-1) / the latter (a-2) The polyacetal resin composition according to any one of claims 1 to 4, which is a polyacetal copolymer copolymerized at a ratio (weight ratio) of 99.9 / 0.1 to 80.0 / 20.0.   Further, at least one selected from an antioxidant, a heat stabilizer, a processability improver, a weather resistance (light) stabilizer, an impact resistance improver, a slidability improver, a gloss control agent, a filler, and a colorant. The polyacetal resin composition according to any one of claims 1 to 6, comprising:   The molded article formed with the polyacetal resin composition of any one of Claims 1-7. (1) The amount of formaldehyde generated when a molded product with a thickness of 2 mm is stored for 3 hours in a sealed space at a temperature of 60 ° C. and saturated humidity is 2.0 μg / g or less per unit weight of the molded product, and / or (2) The molded product according to claim 8, wherein the amount of formaldehyde generated when a molded product having a thickness of 2 mm is stored for 24 hours in a sealed space at a temperature of 80 ° C is 2.0 µg / g or less per unit weight of the molded product. 10. The molded product of polycarbonate resin coexisting in a non-contact state in the sealed space when the molded product is stored for 200 hours in a sealed space at a temperature of 120 ° C. and saturated humidity. Molded products.

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