JP2007070574A - Polyacetal resin composition and molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyacetal resin composition capable of suppressing a formaldehyde emission to a very low level and of suppressing mold deposit and bleed-out coming from additives. <P>SOLUTION: The polyacetal resin composition is prepared by formulating (A) 100 pts.wt. polyacetal resin with (B) 0.01 to 5.0 pts.wt. specified hydrazone compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a polyacetal resin composition capable of suppressing the amount of formaldehyde generated to an extremely low level, and suppressing the occurrence of deposits (mold deposit) on a mold in molding and bleeding out in a molded product, and the resin composition. It relates to the formed article.

  Polyacetal resin has excellent mechanical properties, fatigue resistance, friction and wear resistance, chemical resistance and moldability, so it can be used for automobile parts, electrical / electronic equipment parts, other precision machine parts, building materials / piping members, Widely used in fields such as daily life and cosmetic parts and medical parts.

  However, with the expansion and diversification of uses, there is a demand for a polyacetal resin that is more excellent in thermal stability and generates a very small amount of formaldehyde. In general, formaldehyde is chemically active, and when oxidized, it becomes formic acid, which adversely affects the heat resistance of the polyacetal resin and the properties of other resins that are present in the vicinity, or if a resin that generates formaldehyde is used in electrical or electronic equipment parts. In some cases, metal contact parts are corroded or discolored due to the adhesion of organic compounds, causing contact failure. In addition, the amount of formaldehyde generated from the polyacetal resin molded product under a normal use condition is extremely small, but it is one of the factors that contaminate the working environment in the parts assembly process and the living environment around the use of the final product. Furthermore, the generation of a large amount of formaldehyde during molding generates paraformaldehyde on the mold surface, which causes mold deposits. These are the reasons why a polyacetal resin material in which the amount of formaldehyde generated is extremely reduced is desired.

  Conventionally, in order to stabilize the chemical structure of the polyacetal resin, homopolymers are esterified by acetylation or the like at the polymer ends, and copolymers are adjacent carbons such as trioxane, cyclic ether, and cyclic formal during polymerization. A method is known in which, after copolymerization with a monomer having a bond, an unstable terminal portion is decomposed and removed to form an inactive stable terminal. However, cracking also occurs in the main chain of the polymer during heating, and the above treatment alone cannot be used to prevent it. In practice, the addition of stabilizers (antioxidants, other stabilizers, etc.) It is mandatory.

  For example, steric hindered phenolic compounds (hindered phenols) and steric hindered amine compounds (hindered amines) are known as antioxidants added to polyacetal resins, and other stabilizers include melamine, alkali metals. And alkaline earth metal hydroxides, organic acid salts and inorganic acid salts. Usually, the antioxidant is used in combination with other stabilizers. However, even if such a stabilizer is used, it is difficult to significantly suppress formaldehyde generated from the molded product of the polyacetal resin.

Patent Document 1 discloses a composition containing a polyacetal copolymer and a dicarboxylic acid dihydrazide (an aliphatic dicarboxylic acid dihydrazide having 3 to 10 carbon atoms, an aromatic dicarboxylic acid dihydrazide, an alicyclic dicarboxylic acid dihydrazide, or the like). When such a carboxylic acid dihydrazide is used, the thermal stability is improved to some extent and the generation of formaldehyde can be suppressed, but the moldability is low, mold deposits are generated, and the carboxylic acid hydrazide oozes out from the molded product. appear.
US Pat. No. 3,152,101 (columns 1 and 3)

  An object of the present invention is to provide a polyacetal resin composition and a molded article that can suppress the amount of formaldehyde generated to an extremely low level and can suppress mold deposits and bleed-outs derived from additives.

  Another object of the present invention is that the amount of formaldehyde generated can be suppressed to a low level, and physical properties such as long-term stability, heat resistance, processing characteristics, weather resistance (light) resistance, impact resistance, and slidability are improved. The object is to provide a polyacetal resin composition and a molded article.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventor can not only suppress the amount of formaldehyde generated to an extremely low level when blending a specific hydrazone compound with the polyacetal resin, but also can form mold deposits and bleeds derived from additives. The present inventors have found that the out-of-out can be suppressed and have completed the present invention.

That is, the present invention
(A) For 100 parts by weight of polyacetal resin,
(B) It relates to a polyacetal resin composition comprising 0.01 to 5.0 parts by weight of at least one compound selected from the hydrazone compound represented by the following formula (1) and the hydrazone compound represented by the following formula (2). is there.

(In the formula, R ^{1 to} R ³ represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and may be the same or different. N represents an integer of 1 or 2, and when n is 1, A is —R ⁴ , —CONH ₂ or —COR ⁴ (R ⁴ is a monovalent hydrocarbon group having 1 to 30 carbon atoms), and when n is 2, A is —R ⁵ — or —CO—R ⁵ —. CO— (R ⁵ represents a divalent hydrocarbon group having 1 to 30 carbon atoms)

(In formula, R < ⁶ > -R < ⁹ > shows a hydrogen atom or a C1-C30 hydrocarbon group, and may be same or different, respectively.)

  In the present invention, since the specific hydrazone compound is added to the polyacetal resin, the amount of formaldehyde generated can be suppressed to an extremely low level. Furthermore, since mold deposits derived from the hydrazone compound as an additive and bleed out in the molded product can be remarkably suppressed, the moldability and the quality of the molded product can be improved. The suppressive effect of formaldehyde generation by the specific hydrazone compound used in the present invention is a specific one that is not impaired by the presence of other additives, and other additives (antioxidants, heat stabilizers, By adding processing stabilizers, weather resistance (light) stabilizers, impact resistance improvers, slidability improvers, gloss control agents, fillers, colorants, etc., various properties (long term) Stability, heat resistance, processing characteristics, weather resistance (light) resistance, impact resistance, slidability, etc.) can also be improved.

The polyacetal resin composition of the present invention comprises (B) 0.01 to 5.0 parts by weight of a specific hydrazone compound with respect to 100 parts by weight of (A) polyacetal resin.
(A) Polyacetal resin The polyacetal resin used in the present invention is a polymer compound having an oxymethylene group (—OCH ₂ —) as a main constituent unit, and a polyacetal homopolymer consisting essentially only of repeating oxymethylene units, A typical example is a polyacetal copolymer having other comonomer units in addition to oxymethylene units, and basically has a linear molecular structure. Further, a polyacetal copolymer having a branched structure or a crosslinked structure introduced by copolymerizing a branch-forming component or a crosslinking-forming component, a block copolymer or graft having a repeating unit of an oxymethylene group and another polymer unit. Copolymers are also included. These polyacetal resins can be used alone or in combination of two or more. Among these, a combination of a linear polyacetal resin and a small amount of a branched or cross-linked polyacetal resin is one preferred example.

  In general, a polyacetal homopolymer is produced by polymerization of anhydrous formaldehyde or trioxane (a cyclic trimer of formaldehyde), and is usually stabilized against thermal decomposition by esterifying its terminal.

  A polyacetal copolymer is generally produced by copolymerizing formaldehyde or a cyclic oligomer of formaldehyde as a main monomer and a compound selected from cyclic ether or cyclic formal as a comonomer. To stabilize against thermal decomposition. 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 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, such 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.
(B) Hydrazone compound A feature of the present invention is that generation of formaldehyde can be remarkably suppressed by adding a specific hydrazone compound to a polyacetal resin. Another feature is that by using such a hydrazone compound, mold deposits and bleed-out derived from the compound are suppressed, and the processing stability of the polyacetal resin is remarkably improved.

  The specific hydrazone compound used in the present invention is a hydrazone compound represented by the formula (1) and a hydrazone compound represented by the formula (2).

In Formula (1), R < ¹ > -R < ³ > shows a hydrogen atom or a C1-C30 hydrocarbon group, and may be same or different, respectively. Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a s-butyl group, a t-butyl group, and a linear or branched alkyl group, cyclopentyl And a cycloalkyl group such as a group and a cyclohexyl group, a phenyl group, a naphthyl group, an aromatic group having a substituent on these rings, and an alkyl group having an aromatic group bonded thereto. R ^{1 to} R ³ may have an unsaturated group.

In Formula (1), n represents an integer of 1 or 2, and when n is 1, A is —R ⁴ (R ⁴ is a monovalent hydrocarbon group having 1 to 30 carbon atoms), —CONH ₂ Or —COR ⁴ (R ⁴ is a monovalent hydrocarbon group having 1 to 30 carbon atoms), and when n is 2, A is —R ⁵ — or —CO—R ⁵ —CO— (R ⁵ is 1 carbon atom) To 30 divalent hydrocarbon groups).

When A is —R ⁴ or —COR ⁴ , examples of the hydrocarbon group for R ⁴ include an alkyl group, a cycloalkyl group, a monovalent aromatic group, and an alkyl group to which an aromatic group is bonded. When A is —R ⁵ — or —CO—R ⁵ —CO—, the hydrocarbon group for R ⁵ is an alkylene group, a cycloalkylene group, a divalent aromatic group, or an alkylene group to which an aromatic group is bonded. Is exemplified. R ⁴ and R ⁵ may have an unsaturated group.

Moreover, in Formula (2), R < ⁶ > -R < ⁹ > shows a hydrogen atom or a C1-C30 hydrocarbon group, and may respectively be same or different. Examples of the hydrocarbon group having 1 to 30 carbon atoms include those exemplified in R ¹ to R ³ of formula (1).

  Specific examples of the hydrazone compound (1) having such a structure include 2-propanone = hydrazone, benzaldehyde = hydrazone, diphenylethanedione = bis (phenylhydrazone), 1,4-[(3-phenylethylidene) hydrazino]. Benzene, 1,4-[(3-phenylpropylidene) hydrazino] benzene, 2- (1-methylethylidene) hydrazinecarboxamide, 2- (1-ethylethylidene) hydrazinecarboxamide, formaldehyde adduct of monocarboxylic acid hydrazide, dicarboxylic acid Examples include hydrazide formaldehyde adducts, monocarboxylic hydrazide acetaldehyde adducts, dicarboxylic hydrazide acetaldehyde adducts, and the like.

  Specific examples of the hydrazone compound (2) include 2-propanone = (1-methylethylidene) hydrazone, 2-propanone = (1-ethylethylidene) hydrazone, cyclohexanone = (1-methylpropylidene) hydrazone, cyclohexanone = And (1-methylbutylidene) hydrazone.

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

  The mixing ratio of these hydrazone compounds (B) is 0.01 to 5.0 parts by weight, preferably 0.03 to 3.0 parts by weight, more preferably 0.05 to 2 parts per 100 parts by weight of the polyacetal resin. 0.0 part by weight. If the proportion of the hydrazone compound (B) is too small, it will be difficult to effectively reduce the amount of formaldehyde generated, and if it is too large, the moldability will be impaired and the mechanical strength tends to be lowered.

In the present invention, by using such a specific hydrazone compound (B), the amount of formaldehyde generated is greatly reduced, the moldability (inhibition of mold deposit), and the property of bleeding out of the molded product (bleed out) A polyacetal resin composition excellent in (suppression) can be obtained.
(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, melem, etc., 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. Is melamine-formaldehyde resin, melamine-phenol-formaldehyde resin, benzoguanamine-formaldehyde resin, benzoguanamine- Nord - formaldehyde resin. In addition, melamine derivatives and guanamine derivatives include compounds in which the hydrogen of the amino group 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 hydrazone compound (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 hydrazone 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.

  The resin composition of the present invention can be molded by known molding methods such as injection molding, extrusion molding, compression molding, blow molding, and vacuum molding.

  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.

  More specifically, automobile parts include inner handles, fael trunk openers, seat belt buckles, assist wraps, various interior parts such as switches, knobs, levers, clips, electrical system parts such as meters and connectors, audio equipment, Examples include in-vehicle electrical / electronic parts such as car navigation equipment, parts that come into contact with metal, such as window regulator carrier plates, door lock actuator parts, mirror parts, wiper motor system parts, fuel system parts, etc. it can.

  As electrical / electronic components, components or members of equipment with many metal contacts, for example, audio equipment such as cassette tape recorders and CD / DVD players, video equipment such as VTRs, 8mm video cameras, digital video cameras, and copying Examples thereof include components or members of OA equipment such as a machine, a facsimile machine, a word processor, and a computer. Specific examples of these components or members include a chassis, a gear, a lever, a cam, a pulley, and a bearing. Furthermore, optical and magnetic media parts at least partially composed of a polyacetal resin molded product, such as a metal tape cassette for music, a digital audio tape cassette, an 8 mm video tape cassette, a digital video cassette, a floppy disk cartridge, a mini disk cartridge, The present invention can also be applied to parts such as a DVD disk cartridge.

  Furthermore, the polyacetal resin molded product of the present invention includes lighting equipment, fittings, piping, faucets, faucets, toilet peripheral equipment parts and other building materials and piping parts, fasteners, stationery, lip balm / lipstick containers, washers, water purifiers, It is suitably used for a wide range of life-related parts, makeup-related parts, and medical-related parts such as spray nozzles, spray containers, aerosol containers, general containers, and needle holders.

  Particularly in the automobile field, the interior of the vehicle is often placed in a closed environment, and the interior of the vehicle may reach a considerably high temperature, and the resin composition of the present invention with a small amount of formaldehyde generated is a molded product in this field. Are particularly preferably used.

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

In Examples and Comparative Examples, the amount of formaldehyde generated from the molded product, the moldability (mold deposit), and the bleeding property (bleed out) from the molded product were evaluated as follows.
[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.
[Moldability (mold deposit)]
Using the polyacetal resin compositions prepared in Examples and Comparative Examples, a disk-shaped molded product (diameter 20 mm × thickness 1 mm) was continuously molded (500 shots) with a 30-t injection molding machine (molding temperature 200 ° C.), and gold The degree of mold deposit (mold deposit) was evaluated according to the following criteria.

○: No mold deposit is observed Δ: Slight mold deposit is observed ×: Significant mold deposit is observed
[Bleed out from molded products]
In the evaluation of the amount of formaldehyde generated from the wet molded product (above), the surface of the molded product of the flat test piece taken out after the heat treatment in the thermostat is visually observed, and the extent of the exudate (bleed out) Was evaluated according to the following criteria.

○: No bleed-out is observed at all Δ: Slight bleed-out is observed ×: Remarkable bleed-out is observed
Examples 1-21
After mixing hydrazone compound, antioxidant, heat stabilizer, processability improver, weather resistance (light) stabilizer, and other additives in 100 parts by weight of polyacetal resin in the proportions shown in Tables 1 to 3, one place A pellet-shaped composition was prepared by feeding to a main feed port of a 30 mm diameter twin-screw extruder (cylinder temperature 200 ° C.) having a vent port, melt-kneading and extruding. Using the obtained pellet-shaped composition, the amount of formaldehyde generated, mold deposit, and bleed-out were evaluated by the above evaluation methods. The results are shown in Tables 1-3.
Comparative Examples 1-10
For comparison, an example in which no hydrazone compound was added was evaluated in the same manner as described above. The results are shown in Tables 1-3.

The polyacetal resins, hydrazone compounds, antioxidants, heat stabilizers, processing stabilizers, weathering (light) stabilizers, and other additives used in Examples and Comparative Examples are as follows.
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)
(A-2): Polyacetal resin copolymer (copolymer of trioxane and 1,3-dioxolane, 3.6% by weight copolymerization of 1,3-dioxolane, melt index = 27 g / 10 min)
The melt index is a value determined under conditions of a temperature of 190 ° C. and a load of 2.16 kgf (21.2 N) according to ASTM-D1238.
B. Hydrazone compound (b-1): 1,4-[(3-phenylpropylidene) hydrazino] benzene (b-2): 2- (1-methylethylidene) hydrazine carboxamide (b-3): formaldehyde of pentadecanedioic acid dihydrazide Adduct (b-4): cyclohexanone = (1-methylbutylidene) hydrazone C.I. Antioxidant (c-1): Triethylene glycol bis [3- (3-tert-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): magnesium oxide.
E. Processability improver (e-1): ethylenebisstearylamide (e-2): polyethylene oxide [molecular weight: 35000]
F. Weathering (light) stabilizer (f-1): 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] benzotriazole (f-2): bis (1,2 , 2,6,6-pentamethyl-4-piperidyl) sebacate.
G. Other additives (g-1): Acrylic core-shell polymer [Takeda Pharmaceutical Co., Ltd., Staphyloid PO]
(G-2): Thermoplastic polyurethane [manufactured by Nippon Milactron Co., Ltd., Miractolan E]
(G-3): Carbon black (acetylene black)
(G-4): Glass fiber (a chopped strand having a diameter of 9 μm and a length of 3 mm).

  As is apparent from the table, the resin composition of the example has an extremely small amount of formaldehyde generated as compared with the comparative example. Furthermore, it is possible to improve the moldability by suppressing the occurrence of mold deposits, and to prevent the seepage and improve the quality of the molded product.

Claims (16)

(A) For 100 parts by weight of polyacetal resin,
(B) A polyacetal resin composition comprising 0.01 to 5.0 parts by weight of at least one compound selected from a hydrazone compound represented by the following formula (1) and a hydrazone compound represented by the following formula (2).

(Wherein, R ¹ to R ³ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, good .n be different in each identical an integer of 1 or 2, when n is 1, A is —R ⁴ , —CONH ₂ or —COR ⁴ (R ⁴ is a monovalent hydrocarbon group having 1 to 30 carbon atoms), and when n is 2, A is —R ⁵ — or —CO—R ⁵ —. CO— (R ⁵ represents a divalent hydrocarbon group having 1 to 30 carbon atoms)

(In formula, R < ⁶ > -R < ⁹ > shows a hydrogen atom or a C1-C30 hydrocarbon group, and may be same or different, respectively.)   The polyacetal resin composition according to claim 1, wherein the polyacetal resin (A) is a polyacetal copolymer.   The polyacetal resin (A) comprises 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 claim 2, which is a polyacetal copolymer obtained by copolymerization at a ratio (weight ratio) of 99.9 / 0.1 to 80.0 / 20.0.   Furthermore, the polyacetal resin composition in any one of Claims 1-3 which contains antioxidant (C) in the ratio of 0.01-5.0 weight part with respect to 100 weight part of polyacetal resin (A).   The polyacetal resin composition according to claim 4, wherein the antioxidant (C) is a hindered phenol compound.   Furthermore, the polyacetal resin composition in any one of Claims 1-5 which contain a heat-resistant stabilizer (D) in the ratio of 0.01-5.0 weight part with respect to 100 weight part of polyacetal resin (A).   The heat-resistant stabilizer (D) is at least one selected from organic carboxylic acid metal salts, basic nitrogen-containing compounds, alkali or alkaline earth metal compounds, hydrotalcite, zeolites, and phosphine compounds. Polyacetal resin composition.   Furthermore, the polyacetal resin composition in any one of Claims 1-7 which contain a workability improving agent (E) in the ratio of 0.01-5.0 weight part with respect to 100 weight part of polyacetal resin (A).   The polyacetal resin composition according to claim 8, wherein the processability improver (E) is at least one selected from a long chain fatty acid, a long chain fatty acid derivative, a polyalkylene glycol, a silicone compound, and an olefin wax.   Furthermore, the polyacetal resin composition of any one of Claims 1-9 which contains a weather resistance (light) stabilizer (F) in the ratio of 0.01-5.0 weight part with respect to 100 weight part of polyacetal resin (A).   Weather resistance (light) stabilizer (F) is a benzotriazole compound, a benzophenone compound, an aromatic benzoate compound, a cyanoacrylate compound, an oxalic acid anilide compound, a hydroxyphenyl-1,3,5-triazine compound, and The polyacetal resin composition according to claim 10, wherein the polyacetal resin composition is at least one selected from hindered amine compounds.   The weather resistance (light) stabilizer (F) comprises a benzotriazole compound and a hindered amine compound in a ratio (weight ratio) of the former / the latter = 99.5 / 0.5 to 0.5 / 99.5. 11. The polyacetal resin composition according to 11.   The polyacetal resin composition according to any one of claims 1 to 12, further comprising at least one selected from an impact resistance improver, a slidability improver, a gloss control agent, a filler, and a colorant.   A molded article formed of the polyacetal resin composition according to any one of claims 1 to 13. (1) The amount of formaldehyde generated when a molded article having a thickness of 2 mm is stored for 3 hours in a sealed space of saturated humidity at a temperature of 60 ° C. is 2 μg / g or less per unit weight of the molded article, and / or (2) temperature. The molded product according to claim 14, wherein the amount of formaldehyde generated when a molded product having a thickness of 2 mm is stored in a sealed space at 80 ° C for 24 hours is 2 µg / g or less per unit weight of the molded product. The molded article according to claim 14 or 15, which is an automobile part, an electric / electronic part, a building material / piping part, a daily / cosmetic part or a medical part.