JP2021036018A - Polyacetal resin composition and method for producing the same - Google Patents

Abstract

To provide a polyacetal resin composition which is excellent in weather resistance, suppresses surface glossiness, significantly suppresses an amount of formaldehyde to be generated from its molded article and stably suppresses mold deposit during molding, and a method for producing the same.SOLUTION: A polyacetal resin composition contains (A) 100 pts.mass of a polyacetal polymer, (B) 0.01-0.30 pts.mass of a hindered phenolic antioxidant, (C) 0.01-0.50 pts.mass of an aliphatic carboxylic acid hydrazide, (D) 0.001-0.50 pts.mass of a hydantoin compound having two hydrazino carbonylalkyl groups, (E) 0.001-0.30 pts.mass of an alkaline earth metal salt of an aliphatic carboxylic acid, (F) 0.2-1.0 pts.mass of a hindered amine compound, (G) 0.2-1.0 pts.mass of an ultraviolet absorber, and (H) 1-50 pts.mass of a core-shell polymer having a core of a rubbery polymer and a shell of a glassy polymer composed of a vinyl-based copolymer, in which the total amount of (C) and (D) is 0.03-0.55 pts.mass with respect to 100 pts.mass of (A) the polyacetal polymer.SELECTED DRAWING: None

Description

The present invention is a polyacetal resin composition in which the molded product has excellent weather resistance, surface gloss is suppressed, the amount of formaldehyde generated from the molded product is remarkably suppressed, and mold deposit during molding is stably suppressed. And its manufacturing method.

As is well known, polyacetal resins have been used in an extremely wide range of fields in recent years as engineering resins having excellent physical properties such as mechanical properties and electrical properties, or chemical properties such as chemical resistance and heat resistance. However, with the expansion of the field in which polyacetal resin is used, further peculiarity may be required for the property as a material thereof.

As one of such peculiarities, there is a demand for the development of a material having excellent weather resistance, suppressing surface gloss, reducing formaldehyde generation, and stably suppressing mold deposit during molding. .. For example, in the fields of interior and exterior parts such as automobiles and optical machines, there is little gloss for the purpose of suppressing irritation to the eyes due to light reflection, giving a sense of quality, and preventing malfunction of equipment due to light reflection. That is, in many cases, one with less light reflection is required.

Also, in the fields of general electrical equipment, building materials, etc., there are increasing opportunities to use various materials in combination according to the purpose, but polyacetal resin has better surface gloss than other general resin materials. Therefore, in products incorporating various materials, there is a lack of harmony with other types of materials, and in order to use them in fields where surface appearance is important, products with controlled gloss are required.

In addition, many resin molded products used in the above fields are exposed to sunlight, and the resin material is required to have excellent weather resistance.

Further, in these fields, a resin material in which the generation of formaldehyde is remarkably reduced is strongly required from the viewpoint of environmental hygiene or prevention of unfavorable action on precision equipment. Further, from the viewpoint of productivity, it is required to develop a material in which the mold deposit at the time of molding is stably suppressed.

As a technique for imparting low gloss and weather resistance to such a requirement, it is disclosed that a weather (light) stabilizer and a core-shell polymer are blended with a polyacetal resin (Patent Document 1).

Further, it is known that various foraldehyde trapping agents are blended in a polyacetal resin in order to reduce the generation of formaldehyde. For example, a blending of an oxazoline compound as a formaldehyde trapping agent (Patent Document 2), glyoxydiureid Compound compounds (Patent Document 3), hydrazide compounds (Patent Documents 4 and 5), guanamine compounds (Patent Document 6), and the like are known.

Further, it is also known that a weather-resistant (light) stabilizer, a core-shell polymer and an isocyanate compound are blended with a polyacetal resin for low gloss, weather resistance and low formaldehyde generation (Patent Document 7).

Japanese Unexamined Patent Publication No. 5-179104 Japanese Unexamined Patent Publication No. 5-125255 Japanese Unexamined Patent Publication No. 10-182928 Japanese Unexamined Patent Publication No. 2005-162909 Japanese Unexamined Patent Publication No. 2005-163019 International Publication No. 2004/058875 Japanese Unexamined Patent Publication No. 2008-81530

According to the composition disclosed in Patent Document 1, both weather resistance and low glossiness are imparted. Further, the compositions disclosed in Patent Documents 2 to 6 can be expected to reduce the amount of formaldehyde generated. According to the composition disclosed in Patent Document 7, weather resistance and low glossiness and reduction in the amount of formaldehyde generated can be expected.

However, in the techniques disclosed in these documents, a polyacetal resin material having excellent weather resistance, suppressed surface gloss, significantly reduced formaldehyde generation, and stably suppressed mold deposit during molding. Can't get.

Further, it is extremely difficult to obtain a resin material having all of these characteristics by selecting the components to be blended in the polyacetal resin and adjusting the blending amount.

That is, the effect is antagonized depending on the compounding ingredients used or a combination thereof, and if any of the characteristics of weather resistance, low glossiness, low formaldehyde generation characteristic, and low mold deposit generation characteristic is to be improved, the other characteristics are to be improved. The characteristics are often impaired.

The present invention improves such a conventional technique, has excellent weather resistance, suppresses surface gloss, remarkably suppresses the amount of formaldehyde generated from the molded product, and stably suppresses mold deposit during molding. It is an object of the present invention to provide a polyacetal resin composition and a method for producing the same.

An object of the present invention has been achieved by:

1. 1. At least 100 parts by mass of (A) polyacetal polymer,
(B) Hindered phenolic antioxidant 0.01 to 0.30 parts by mass,
(C) 0.01 to 0.50 parts by mass of aliphatic carboxylic acid hydrazide,
(D) 0.001 to 0.50 parts by mass of a hydantoin compound having two hydradinocarbonylalkyl groups,
(E) Alkaline earth metal salt of aliphatic carboxylic acid 0.001 to 0.30 parts by mass,
(F) Hindered amine compound 0.2 to 1.0 parts by mass,
(G) Ultraviolet absorber 0.2 to 1.0 parts by mass,
(H) 1 to 50 parts by mass of a core-shell polymer having a rubber-like polymer core and a glass-like polymer shell made of a vinyl-based copolymer.
And will contain
A polyacetal resin composition in which the total amount of (C) and (D) is 0.03 to 0.55 parts by mass with respect to 100 parts by mass of the (A) polyacetal polymer.
2. The polyacetal resin composition according to 1 above, wherein the (F) hindered amine compound has a tertiary nitrogen content of a piperidine derivative having a steric hindrance group.
3. 3. The polyacetal resin composition according to 1 or 2 above, wherein the (C) aliphatic carboxylic acid hydrazide is sebacic acid dihydrazide.
4. The polyacetal resin composition according to any one of 1 to 3 above, wherein the alkaline earth metal salt of the (E) aliphatic carboxylic acid is at least one selected from calcium stearate and calcium 12-hydroxystearate.
5. (D) The polyacetal resin composition according to any one of 1 to 4, wherein the hydantoin compound having two hydradinocarbonylalkyl groups is 1,3-bis (hydradinocarbonoethyl) -5-isopropylhydantoin.
6. The (F) hindered amine compound is tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, 1,2,3,4-butanetetra. Carboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β', β'-tetramethyl-3,9- (2,4,8,10-tetraoxaspiro [5] .5] Undecane) At least one selected from a condensate with diethanol, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol, the above 1-5. The polyacetal resin composition according to any one.
7. The (G) UV absorbers are 2- (2H-benzotriazole-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol and N- (2-ethylphenyl) -N'. The polyacetal resin composition according to any one of 1 to 6 above, which is at least one selected from − (2-ethoxyphenyl) oxalic acid diamide.
8. The polyacetyl resin composition according to any one of 1 to 7, wherein the glassy polymer forming the shell of the core-shell polymer (H) is made of a vinyl-based copolymer having an oxygen-containing polar group.
9. The method for producing a polyacetal resin composition according to any one of 1 to 8 above, wherein the polyacetal polymer (A) has a trioxane as a main monomer (a) and has at least one carbon-carbon bond. One or more selected from cyclic formal is used as a comonomer (b), copolymerized using a heteropolyacid as a polymerization catalyst (c), and then carbonates, hydrogen carbonates and carboxylates of alkali metals or alkaline earth metals. Alternatively, a method for producing a polyacetal resin composition, which is a polyacetal copolymer obtained by adding the hydrate (d) thereof, melt-kneading the mixture, and deactivating the polymerization catalyst (c).

According to the present invention, a polyacetal resin composition having excellent weather resistance, suppressed surface gloss, suppressing the generation of formaldehyde from a molded product to an extremely low level, and stably suppressing a mold deposit during molding, and a polyacetal resin composition. Molded articles are provided.

Hereinafter, the present invention will be described in detail.
<(A) Polyacetal polymer>
The polyacetal polymer (A) used in the present invention _{may be a homopolymer having an oxymethylene group (-OCH 2-} ) as a constituent unit, or a copolymer having another comonomer unit in addition to the oximethylene unit. It may be a copolymer, and is preferable.

Generally, it is produced by copolymerizing formaldehyde or a cyclic compound of formaldehyde as a main monomer and a compound selected from cyclic ether or cyclic formal as a comonomer, and usually at the end by thermal decomposition, (alkali) hydrolysis or the like. It is stabilized by removing unstable parts.

In particular, trioxane, which is a cyclic trimer of formaldehyde, is generally used as the main monomer. Trioxane is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst, and is used by purifying it by a method such as distillation. The trioxane used for the polymerization preferably contains as little impurities as possible, such as water, methanol, and formic acid.

As the comonomer, general cyclic ether and cyclic formal, glycidyl ether compounds capable of forming a branched structure or a crosslinked structure, or the like can be used alone or in combination of two or more.

The polyacetal polymer as described above can generally be obtained by adding an appropriate amount of a molecular weight modifier and performing cationic polymerization using a cationic polymerization catalyst. The molecular weight modifier used, cationic polymerization catalyst, polymerization method, polymerization apparatus, deactivation treatment of catalyst after polymerization, end stabilization treatment method of crude polyacetal polymer obtained by polymerization, etc. are known from many documents. Yes, and basically any of them can be used.

Particularly preferable methods for producing a polyacetal polymer include the following. That is, trioxane is used as the main monomer (a), one or more selected from cyclic ether having at least one carbon-carbon bond and cyclic formal is used as the comonomer (b), and a heteropolyacid is used as the polymerization catalyst (c). It is copolymerized, and then a carbonate, a hydrogen carbonate, a carboxylate or a hydrate (d) thereof of an alkali metal or an alkaline earth metal is added and melt-kneaded to inactivate the polymerization catalyst (c). It is a thing. By using the polyacetal polymer by this method, the amount of formaldehyde generated from the molded product and the generation of mold deposit during molding can be further reduced.

The heteropolyacid used as the polymerization catalyst (c) is a general term for polyacids produced by dehydration condensation of different types of oxygen acids, in which a specific different type of element is present in the center and a condensate acid shares an oxygen atom. It has a mononuclear or dinuclear complex ion formed by condensation of groups.

Specific examples of the above heteropolyacids include phosphomolybdic acid, phosphotungstic acid, phosphomolybd tungstic acid, phosphomolibd vanadic acid, phosphoribd tongue tungstic acid, lintang tungstic acid, silicate tungstic acid, silicate molybdic acid, and kei. Examples thereof include molybdate tungstic acid and molybdate tungstic acid tovanadic acid. Above all, in consideration of the stability of polymerization and the stability of the heteropolyacid itself, the heteropolyacid is preferably any one or more of silicate molybdic acid, silicate tungstic acid, phosphomolybdic acid and phosphotungstic acid.

The amount of the heteropolyacid used varies depending on the type thereof, and the polymerization reaction can be adjusted by appropriately changing the amount, but in general, it is 0.05 to 100 ppm (hereinafter referred to as “hereinafter”) with respect to the total amount of the monomers to be polymerized. It is in the range of mass / mass ppm), preferably 0.1 to 50 ppm.

As the polymerization apparatus, a reaction tank with a stirrer, which is generally used in the batch type, can be used, and as a continuous type, a conider, a 2-screw type continuous extrusion mixer, a 2-screw paddle type continuous mixer, etc. , The continuous polymerization apparatus such as trioxane proposed so far can be used, and two or more types of polymerization machines can be used in combination.

The polymerization method is not particularly limited, but as previously proposed, a trioxane, a comonomer, and a heteropolyacid as a polymerization catalyst are sufficiently mixed while maintaining a liquid phase state in advance, and the obtained reaction raw material is obtained. If the mixed solution is supplied to the polymerization apparatus and the copolymerization reaction is carried out, the required amount of catalyst can be reduced, and as a result, it is advantageous to obtain a polyacetal copolymer having a smaller amount of formaldehyde emission, which is a more preferable polymerization method. Is. The polymerization temperature is in the temperature range of 60 to 120 ° C.

In the present invention, when the above-mentioned main monomer (a) and comonomer (b) are polymerized to prepare a polyacetal copolymer, a chain transfer agent known for adjusting the degree of polymerization, for example, a low molecular weight line such as methylal, is used. It is also possible to add a state acetal or the like.

Further, it is desirable that the polymerization reaction is carried out in a state in which impurities having active hydrogen, for example, water, methanol, formic acid, etc. are substantially not present, for example, in a state where each of these is 10 ppm or less. It is desirable to use trioxane, cyclic ether and / or cyclic formal prepared to contain as little as possible as the main monomer or comonomer.

A polyacetal polymer (crude polyacetal polymer) containing a polymerization catalyst obtained by polymerization as described above and having an unstable portion at the end thereof, and an alkali metal or alkaline earth metal carbonate or carbonic acid. A hydrogen salt, a carboxylate or a hydrate (d) thereof is melt-kneaded to deactivate the polymerization catalyst and to reduce and stabilize unstable terminal groups of the polyacetal polymer (crude polyacetal polymer). ..

The molecular weight of the (A) polyacetal polymer used in the present invention is not particularly limited, but the weight average molecular weight equivalent to PMMA (polymethylmethacrylate) determined by the SEC (size exclusion chromatography) method is 10,000 to 400. About 000 is preferable. Further, the melt index (measured at 190 ° C. and a load of 2.16 kg according to ASTM-D1238), which is an index of resin fluidity, is preferably 0.1 to 100 g / 10 minutes, and more preferably 0.5 to 100 g. 80 g / 10 minutes.

It is particularly preferable that the polyacetal polymer (A) used in the present invention has specific terminal properties. Specifically, the amount of hemiformal terminal groups is 1.0 mmol / kg or less, the amount of formyl terminal groups is 0.5 mmol / kg or less, and the amount of unstable terminal groups is 0.5% by mass or less.

Here, the hemiformal terminal group is represented by -OCH ₂ OH, and is also referred to as a hydroxymethoxy group or a hemiacetal terminal group. The formyl terminal group is indicated by -OCHO. The amounts of such hemiformal terminal groups and formyl terminal groups ^{can be determined by 1} H-NMR measurement, and the specific measurement method thereof can be referred to the method described in JP-A-2001-11143.

The unstable terminal amount indicates the amount of the portion that is present at the terminal portion of the polyacetal polymer and is unstable to heat or base and easily decomposed. To obtain such an unstable terminal amount, 1 g of a polyacetal polymer was placed in a pressure-resistant airtight container together with 100 ml of a 50% (volume%) methanol aqueous solution containing 0.5% (volume%) ammonium hydroxide and heat-treated at 180 ° C. for 45 minutes. After that, the amount of formaldehyde decomposed and eluted in the solution obtained by cooling and opening the package was quantified and expressed in% by volume with respect to the polyacetal polymer.

The polyacetal polymer (A) used in the present invention preferably has a hemiformal terminal group amount of 1.0 mmol / kg or less, more preferably 0.6 mmol / kg or less. The amount of formyl terminal groups is preferably 0.5 mmol / kg or less, more preferably 0.1 mmol / kg or less. The amount of unstable terminals is preferably 0.5% by mass or less, more preferably 0.3% by mass or less. The lower limits of the hemiformal terminal group amount, the formyl terminal group amount, and the unstable terminal amount are not particularly limited.

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

As a method for producing a polyacetal polymer (A) having specific terminal properties satisfying the requirements of the present invention below, for example, the method described in JP-A-2009-286874 can be used. However, the method is not limited to this method.

In the present invention, a polyacetal polymer having a branched or crosslinked structure may be added to the (A) polyacetal polymer and used, in which case the blending amount is 0.01 with respect to 100 parts by mass of the (A) polyacetal polymer. It is ~ 20 parts by mass, and particularly preferably 0.03 to 5 parts by mass.

<(B) Hindered phenolic antioxidant>
The (B) hindered phenolic antioxidant that can be used in the present invention is not particularly limited, and is, for example, a monocyclic hindered phenol compound (for example, 2,6-di-t-butyl-p-). Cresol, etc.), polycyclic hindered phenol compounds linked by groups containing hydrocarbon groups or sulfur atoms (eg, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'- Methylenebis (2,6-di-t-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 4,4'-butylidenebis (3-methyl-6) -T-butylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 4,4'-thiobis (3-methyl-) 6-t-butylphenol), etc.), hindered phenol compounds having an ester group or an amide group (eg, n-octadecyl-3- (4'-hydroxy-3', 5'-di-t-butylphenyl) propionate, n-Octadecyl-2- (4'-hydroxy-3', 5'-di-t-butylphenyl) compound, 1,6-hexanediolbis [3- (3,5-di-t-butyl-4-) Hydroxyphenyl) propionate], triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] (also known as: ethylenebis (oxyethylene) bis [3- (3- (5- (5-) 5-) t-butyl-4-hydroxy-m-tolyl) propionate]), pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,9-bis {2-[ 3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] undecane, 2- t-butyl-6- (3'-t-butyl-5'-methyl-2'-hydroxybenzyl) -4-methylphenylacrylate, 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-t-butyl-4-hydroxyphenyl) propionamide], N, N'-tetramethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionamide], N, N'-hexamethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionamide], N, N'-ethylenebis [3- (3-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-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, N, N'-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) Propionyl] hydrazine, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-t-butyl-3-hydroxy-2, 6-Dimethylbenzyl) isocyanurate and the like are exemplified.

In the present invention, at least one or two or more selected from these antioxidants can be used.

The content of the (B) hindered phenolic antioxidant in the present invention is 0.01 to 0.30 parts by mass with respect to 100 parts by mass of the (A) polyacetal polymer. If the blending amount is less than this amount, the effect is insufficient, and if it is more than this amount, the weather resistance is deteriorated due to the antagonistic action with the hindered amine compound.

<(C) Aliphatic carboxylic acid hydrazide>
Examples of the (C) aliphatic carboxylic acid hydrazide used in the present invention include adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, stearic acid hydrazide and the like. Preferred is sebacic acid dihydrazide, which can capture formaldehyde and can significantly suppress the originally generated mold deposit by using it in combination with a hydantoin compound having a hydrazide group.

In the present invention, (C) an aliphatic carboxylic acid hydrazide can be used in combination of one or more, and the amount added thereof is 0.01 to 0.50 parts by mass with respect to 100 parts by mass of the (A) polyacetal polymer. It is preferably 0.02 to 0.30 parts by mass.

<(D) Hydantoin compound having two hydradinocarbonylalkyl groups>
Examples of the (D) hydantoin compound having two hydradinocarbonylalkyl groups (hereinafter, may be abbreviated as hydantoin compound) of the present invention include 1,3-bis (hydrazinocarbonoethyl) hydantoin and 1,3-bis (hereinafter, may be abbreviated as hydantoin compound). Hydantoin (hydradinocarbonoethyl) -5-methylhydantoin, 1,3-bis (hydrazinocarbonoethyl) -5,5-dimethylhydantoin, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin, etc. At the 5-position of hydantoin, 1 or 2 substituents (a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group, an aryl group having 6 to 10 carbon atoms such as a phenyl group, etc.) The two substituents at the 5-position may form a ring together with the carbon atom at the 5-position. Preferably 1,3-bis (hydrazinocarbonoethyl) -5-isopropyl hydantoin is used.

The (D) hydantoin compound of the present invention captures formaldehyde and suppresses mold deposit by using it in combination with the (C) aliphatic carboxylic acid hydrazide of the present invention. In particular, the effect is great when used in combination with sebacic acid dihydrazide.

In the present invention, one or more of the (D) hydantoin compounds can be used in combination, and the amount added thereof is 0.001 to 0.50 parts by mass with respect to 100 parts by mass of the (A) polyacetal polymer, preferably 0. It is 01 to 0.30 parts by mass.

Further, in the present invention, the effect of the present invention can be obtained if both (C) an aliphatic carboxylic acid hydrazide and (D) a hydantoin compound are contained, but the total amount is based on 100 parts by mass of the (A) polyacetal polymer. It is preferably 0.03 to 0.55 parts by mass. The content mass ratio of (C) and (D) is preferably (C) :( D) = 10: 90 to 99: 1.

<(E) Alkaline earth metal salt of aliphatic carboxylic acid>
The aliphatic carboxylic acid constituting the alkaline earth metal salt of the (E) aliphatic carboxylic acid of the present invention may be a saturated aliphatic carboxylic acid or an unsaturated aliphatic carboxylic acid. Examples of such an aliphatic carboxylic acid include a monovalent or divalent aliphatic carboxylic acid having 10 or more carbon atoms, for example, a monovalent saturated aliphatic carboxylic acid having 10 or more carbon atoms [capric acid, lauric acid, myristic acid]. , Pentadecylic acid, palmitic acid, stearic acid, araquinic acid, bechenic acid, montanic acid and other saturated aliphatic carboxylic acids having 10 to 34 carbon atoms (preferably saturated aliphatic carboxylic acids having 10 to 30 carbon atoms), carbon. Monovalent unsaturated aliphatic carboxylic acid of several tens or more [Saturated aliphatic carboxylic acid having 10 to 34 carbon atoms (preferably 10 to 30 carbon atoms) such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, and erucic acid. (Unsaturated aliphatic carboxylic acid), etc.], divalent aliphatic carboxylic acid with 10 or more carbon atoms (dibasic aliphatic carboxylic acid) [divalent such as sebacic acid, dodecanedioic acid, tetradecanedioic acid, tapsiaic acid, etc. Saturated aliphatic carboxylic acid having 10 to 30 carbon atoms (preferably saturated aliphatic carboxylic acid having divalent 10 to 20 carbon atoms), etc.], divalent unsaturated aliphatic carboxylic acid having 10 or more carbon atoms [decenni An unsaturated aliphatic carboxylic acid having 10 to 30 divalent carbon atoms (preferably an unsaturated aliphatic carboxylic acid having 10 to 20 divalent carbon atoms) such as an acid and dodecene diic acid] can be exemplified.

Further, in the above-mentioned aliphatic carboxylic acid, a part of the hydrogen atom is substituted with a substituent such as a hydroxyl group, and the aliphatic carboxylic acid having one or a plurality of hydroxyl groups in the molecule (for example, 12-hydroxy). It also contains an aliphatic carboxylic acid having a hydroxy-saturated carbon number of 10 to 26 such as stearic acid), and also contains an aliphatic carboxylic acid having a slightly different number of carbon atoms depending on the accuracy of purification.

In the present invention, as the alkaline earth metal, calcium and magnesium are preferable, and calcium is particularly preferable. Alkaline earth metal salts of aliphatic carboxylic acids that are particularly preferable are calcium stearate and calcium 12-hydroxystearate.

The alkaline earth metal salt of the aliphatic carboxylic acid in the polyacetal resin composition can be used in combination of one or more, and the addition amount thereof is 0.001 to 0.30 with respect to 100 parts by mass of the (A) polyacetal polymer. It is by mass, preferably 0.01 to 0.25 parts by mass.

<(F) Hindered amine compound>
The hindered amine compound used in the present invention is not particularly limited, and a hindered amine compound in which the nitrogen of the piperidine derivative having a steric hindrance group is secondary or tertiary is preferably used. A hindered amine compound in which the nitrogen of the piperidine derivative having a sterically hindered group is tertiary is particularly preferably used.

As the hindered amine stabilizer in which the nitrogen of the piperidine derivative having a sterically disordering group used in the present invention is secondary, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 1,2,3 , 4-Butanetetracarboxylic acid and 2,2,6,6-tetramethyl-4-piperidinol and β, β, β', β'-tetramethyl-3,9- (2,4,5,10-tetra) Oxaspiro [5,5] undecane) -condensate with diethanol, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, 1,2, Examples thereof include a condensate of 3,4-butanetetracarboxylic acid, 2,2,6,6-tetramethyl-4-piperidinol and tridecyl alcohol.

Examples of the hindered amine compound in which the nitrogen of the piperidine derivative having a sterically disordering group used in the present invention is tertiary includes bis (1,2,2,6,6-pentamethyl-4-piperidyl) adipate and bis (1-octyl). An aliphatic di or tricarboxylic acid-bis or tripiperidyl ester such as oxy-2,2,6,6-tetramethyl-4-piperidyl sepate (such as an aliphatic dicarboxylic acid-bispiperidyl ester having 2 to 20 carbon atoms), N, N', N'', N'''-tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidine-4-yl) amino)- Triazine-2-yl) -4,7-diazadecan-1,10-diamine, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, bisdecanedioate (2,2,6,6-tetramethyl-1- (octyloxy) -4-piperidinyl) ester, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butylmalonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, methyl-1,2,2,6 6-Pentamethyl-4-piperidyl sebacate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) 1,2,3,4-butane tetracarboxylate, 1,2,3,4-butane Condensate of tetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and tridecyl alcohol, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6 -Condensation of pentamethyl-4-piperidinol with β, β, β', β'-tetramethyl-3,9- (2,4,5,10-tetraoxaspiro [5.5] undecane) -diethanol , Peroxidized 4-butylamino-2,2,6,6-tetramethylpiperidine and 2,4,6-trichloro-1,3,5-triazine, and cyclohexane, N, N'-ethane-1 , 2-Reaction product with diylbis (1,3-propanediamine), 1- [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-t-butyl-4-hirodoxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine and the like can be mentioned.

Particularly preferred are tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) 1,2,3,4-butanetetracarboxylate, 1,2,3,4-butanetetracarboxylic acid. 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β', β'-tetramethyl-3,9- (2,4,5,10-tetraoxaspiro [5.5] Examples thereof include a condensate with undecane) -diethanol and a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol.

In the present invention, one or more of the (F) hindered amine compounds can be used in combination, and the amount added thereof is 0.2 to 1.0 parts by mass, preferably 0.2 to 1.0 parts by mass with respect to 100 parts by mass of the (A) polyacetal polymer. It is 0.4 to 0.8 parts by mass.

(F) If the blending amount of the hindered amine compound is too small, a polyacetal resin composition having excellent weather resistance cannot be obtained. On the contrary, if the blending amount is too large, the mechanical properties are deteriorated and the appearance due to exudation occurs. Problems such as defects occur.

<(G) UV absorber>
Examples of the ultraviolet absorber of the present invention include benzotriazole-based compounds and oxalic acid anilide-based compounds, and these light stabilizers can be used alone or in combination of two or more.

Examples of benzotriazole compounds include 2- (2H-benzotriazole-2-yl) -p-cresol and 2- (2H-benzotriazole-2-yl) -4,6-bis (1-methyl-1-phenyl). Ethyl) phenol, 2- [5-chloro (2H) -benzotriazole-2-yl) -4-methyl-6- (t-butyl) phenol, 2,4-di-t-butyl-6- (5-) Chlorobenzotriazole-2-yl) phenol, 2- (2H-benzotriazole-2-yl) -4,6-di-t-pentylphenol, 2- (2H-benzotriazole-2-yl) -4- ( 1,1,3,3-Tetramethylbutyl) phenol, 2- (2'-hydroxy-3', 5'-di-isoamylphenyl) benzotriazole and other hydroxyl groups and alkyl (alkyl with 1 to 6 carbon atoms) Group-substituted benzotriazoles having an aryl group 2- [2'-hydroxy-3', 5'-bis (α, α-dimethylbenzyl) phenyl] hydroxyl group such as benzotriazole and aralkyl (or aryl) group substitution Benzotriazoles having an aryl group Examples thereof include benzotriazoles having a hydroxyl group such as 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole and an alkoxy (C1-12 alkoxy) group-substituted aryl group. ..

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

Examples of the oxalic acid anilide compound include N- (2-ethylphenyl) -N'-(2-ethoxy-5-t-butylphenyl) oxalic acid diamide and N- (2-ethylphenyl) -N'-(2). Examples thereof include −ethoxyphenyl) oxalic acid diamides and oxalic acid diamides having an aryl group optionally substituted on the nitrogen atom. The oxalic acid anilide compound can be used alone or in combination of two or more.

In the present invention, the amount of the (G) ultraviolet absorber added is 0.2 to 1.0 parts by mass with respect to 100 parts by mass of the (A) polyacetal polymer. It is preferably 0.4 to 0.8 parts by mass. (G) If the amount of the ultraviolet absorber is too small, it is not possible to obtain a polyacere resin composition having excellent weather resistance. On the contrary, if the amount of the ultraviolet absorber is too large, the mechanical properties are deteriorated and exudation occurs. Causes problems such as poor appearance.

<(H) Core-shell polymer having a rubber-like polymer core and a glass-like polymer shell made of a vinyl-based copolymer>
In the present invention, the (H) core-shell polymer has a rubber-like polymer core and a glass-like polymer shell made of a vinyl-based copolymer. It is obtained by a continuous multi-step emulsion polymerization method in which the polymer is sequentially coated with the polymer of a later stage.

When the core-shell polymer has an intermediate phase described later, the intermediate phase may be formed by a multi-step emulsion polymerization method in which the polymer of the later stage penetrates into the polymer of the earlier stage.

At the time of particle generation polymerization, it is preferable to start the emulsion polymerization reaction by adding a monomer, a surfactant and water to the reactor and then adding a polymerization initiator. The first stage polymerization is a reaction to form a rubbery polymer.

Examples of the monomer constituting the rubber-like polymer include a conjugated diene, an alkyl acrylate having an alkyl group having 2 to 8 carbon atoms, and a mixture thereof.

These monomers are polymerized to form a rubbery polymer. Examples of such conjugated diene include butadiene, isoprene, chloroprene and the like, and butadiene is particularly preferably used.

Examples of the alkyl acrylate having an alkyl group having 2 to 8 carbon atoms include ethyl allylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate, and butyl acrylate is particularly preferable.

In the first-stage polymerization, monomers copolymerizable with conjugated diene and alkyl acrylates, such as aromatic vinyl such as styrene, vinyltoluene and α-methylstyrene, cyanide of aromatic vinylidene, acrylonitrile, and methacrylonitrile. Alkyl methacrylates such as vinyl, vinylidene cyanide, methyl methacrylate, and butyl methacrylate can also be copolymerized.

If the first-stage polymerization does not contain conjugated diene, or if it contains conjugated diene but is 20% by mass or less of the total amount of monomers in the first stage, use a small amount of crosslinkable monomer and grafted monomer. Therefore, it is possible to obtain a polymer having higher impact resistance.

Examples of the crosslinkable monomer include aromatic divinyl monomers such as divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene glycol diacrylate, hexanediol diacrylate, hexanediol dimethacrylate, oligoethylene glycol diacrylate, and oligoethylene glycol diacrylate. Alcan polyol polyacrylates such as methacrylate, trimethylol propane diacrylate, trimethylol propane dimethacrylate, trimethylol propane triacrylate, trimethylol propane trimethacrylate, alkane polyol polymethacrylate, etc. can be mentioned, and in particular, butylene glycol diacrylate, Hexadiol diacrylate is preferably used.

Examples of the grafted monomer include unsaturated carboxylic acid allyl esters such as allyl acrylate, allyl methacrylate, diallyl maleate, diallyl fumarate, and diallyl itaconate, and allyl methacrylate is particularly preferably used. Such crosslinkable monomers and grafted monomers are used in the range of 0 to 5% by mass, preferably 0.1 to 2% by mass, respectively, of the total amount of the monomers in the first stage.

The core-shell polymer (H) used in the present invention is preferably a glassy polymer in which the shell phase is made of a vinyl-based copolymer having an oxygen-containing polar group. The core-shell polymer formed of a vinyl-based copolymer in which the shell phase has an oxygen-containing polar group further enhances the matting effect (gloss reducing effect).

Examples of such an oxygen-containing polar group include a hydroxyl group, a group having an ether bond (for example, a glycidyl group), an amide group, an imide group and a nitro group, and a group having a hydroxyl group and an ether bond is particularly preferable.

As the monomer constituting the vinyl-based copolymer having an oxygen-containing polar group, for example, an alcohol (meth) acrylate having two or more oxygen-containing polar groups in the molecule is used. Here, the alcohol having two or more oxygen-containing polar groups in the molecule means an alcohol having at least one oxygen-containing polar group other than the hydroxyl group of the alcohol moiety.

As a specific example of the (meth) acrylate of an alcohol having an oxygen-containing polar group, for example, a (meth) acrylate of an alcohol having a hydroxyl group and / or a gusidyl group is used. Examples of the (meth) acrylate of the alcohol having a hydroxyl group include hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, but hydroxyethyl methacrylate is preferably used.

Examples of the (meth) acrylate of the alcohol having a glycidyl group include glycidyl methacrylate and glycidyl acrylate, but glycidyl methacrylate is preferably used. In addition to the above (meth) acrylate, vinyl monomers having an oxygen-containing polar group such as allyloxyethanol and allylglycidyl ether should also be used as constituents of the vinyl-based copolymer having an oxygen-containing polar group. Can be done.

Examples of the monomer constituting the glassy polymer other than the monomer having an oxygen-containing polar group include alkyl (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate, styrene, and vinyl toluene. , Aromatic vinyl such as α-methylstyrene, vinyl cyanide such as aromatic vinylidene, acrylonitrile, and methacrylonitrile, and vinyl polymerizable monomers such as vinylidene cyanide, but methyl methacrylate, styrene, and the like are particularly preferable. Acrylonitrile or the like is used.

The shell phase is preferably in the range of 10 to 50% by mass of the total core-shell polymer. When this shell phase is less than this mass range, weather resistance may be impaired, and when it is more than this mass range, the mechanical properties of the resin composition obtained by melt-mixing the resulting core-shell polymer are not sufficient. Sometimes.

Further, an intermediate phase may exist between the first stage and the final polymerization phase. For example, a polymerization monomer having a functional group such as glycidyl methacrylate, methacrylic acid, hydroxyethyl methacrylate, a polymerization monomer forming a glassy polymer such as methyl methacrylate, a polymerization monomer forming a rubbery polymer such as butyl acrylate, and the like. The intermediate phase is formed by emulsion polymerization. Such an intermediate phase can be variously selected depending on the properties of the desired core-shell polymer.

The structure of the core-shell polymer having such an intermediate phase is, for example, a multi-layered structure in which another layer exists between the core and the shell, or the intermediate phase is dispersed in the core as fine particles. Some have a salami structure. In more extreme cases of core-shell polymers with salami structures, the intermediate phase to be dispersed may form a new core in the center of the core.

A core-shell polymer having such a structure may occur when a monomer typified by styrene is used as a mesophase constituent monomer. In addition, when a core-shell polymer having an intermediate phase is used, the impact resistance is improved, the flexural modulus is improved, the thermal deformation temperature is raised, and the appearance (surface peeling and pearl luster is suppressed, and the color tone is changed due to a change in refractive index). May be improved.

The emulsion polymerization for the core-shell polymer used in the present invention includes surfactants such as nonionic surfactants, oligomeric anionic or oligomeric nonionic surfactants, and for example, azo-based polymerization initiators and peroxide-based polymerizations. It is carried out using a polymerization initiator such as an initiator.

Examples of the nonionic surfactant used here include ether types such as polyoxyethylene nonylphenyl ether, polyoxyethylene stearyl ether and polyoxyethylene lauryl ether, ester types such as polyoxyethylene monostearate, and polyoxyethylene sorbitan mono. Most of the widely used nonionic surfactants such as sorbitan ester type such as laurate and block polymer type such as polyoxyethylene polyoxypropylene block copolymer can be used.

The oligomer-type anionic or oligomer-type nonionic surfactant is an oligomer-type surfactant that has been conventionally used for emulsion polymers for special purposes.

The core-shell polymer used in the present invention can be taken out in the form of granules, flakes or powder by, for example, the following method.
(1) Latex is produced by a known seed emulsification polymerization method using the above-mentioned surfactant and polymerization initiator. (2) Next, the latex is frozen and thawed to separate the polymer. (3) Subsequently, centrifugal dehydration and drying are performed.

By such an extraction operation, many of the solvents and surfactants used during the emulsion polymerization can be removed. Alternatively, the latex can be dried and used as it is at the stage (2). A spray drying method using a spray dryer is also one of the methods for extracting the core-shell polymer from latex. The core-shell polymer thus taken out may be further pelletized by an extruder and a pelletizer, or may be melt-mixed with the resin as it is.

In the present invention, the addition amount of the core-shell polymer having the core of the (H) rubber-like polymer and the shell of the glass-like polymer composed of the vinyl-based copolymer with respect to 100 parts by mass of the (A) polyacetal polymer is 1 to 50 parts by mass. It is preferably 3 to 20 parts by mass. (H) The core-shell polymer can be used in combination of one or more.

(H) If the amount of the core-shell polymer added is too small, the effect of reducing the surface gloss is not sufficiently exhibited, and even if it is added excessively, the mechanical properties, particularly the rigidity, are significantly reduced, and the thermal stability is observed. Has an unfavorable effect.

By adding (H) the core-shell polymer to the polyacetal resin in combination with (F) hindered amine compound and (G) ultraviolet absorber, the gloss of the surface of the obtained molded product is uniformly reduced, and the calm and high quality is obtained. It gives a feeling and synergistically improves weather resistance.

Furthermore, it retains the excellent mechanical properties of polyacetal resin. In the molded product obtained by adding and blending the core-shell polymer into the polyacetal resin, the core-shell polymer is dispersed on the surface of the molded product in the form of particles of about 0.5 to 2 μm, and at the same time, the surface of the polyacetal resin is roughened. It is considered that the oxygen-containing polar groups are uniformly dispersed on the surface, and the surface of the polyacetal resin molded product is modified to have low gloss.

Practically, the degree of surface gloss is preferably 35% or less, more preferably 30% or less, and particularly preferably 25% or less by the measurement method (using a mirror surface mold) described later.

<Other additives>
The polyacetal resin composition of the present invention may further contain a processing stabilizer, an impact resistance improver, a gloss control agent, a slidability improver, a filler, and a colorant, if necessary, as long as the present invention is not impaired. , Nuclear agent, antistatic agent, surfactant, antibacterial agent, antifungal agent, air freshener, foaming agent, compatibilizer, physical property improver (boric acid or its derivative, etc.), fragrance, etc. can do.
<Manufacturing method of polyacetal resin composition>

The method for producing the polyacetal resin composition of the present invention is not particularly limited, and the polyacetal resin composition can be prepared by various conventionally known methods for preparing the resin composition. For example, (1) a method of mixing all the components constituting the composition, supplying the mixture to an extruder and melt-kneading the mixture to obtain a pellet-shaped composition, and (2) a part of the components constituting the composition. Residual components are supplied from the main feed port of the extruder and melt-kneaded to obtain a pellet-shaped composition. (3) Pellets with different compositions are once prepared by extrusion or the like, and the pellets are mixed. Then, a method of adjusting to a predetermined composition or the like can be adopted.

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 is used at any place from the main feed port to the devolatilization vent port. It is preferable to supply about 0.1 to 10 parts by mass of alcohols to 100 parts by mass of the polyacetal resin, and to volatilize 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 the molded product thereof can be further reduced.

The polyacetal resin composition of the present invention prepared in this manner can be molded by various conventionally known molding methods such as injection molding, extrusion molding, compression molding, vacuum molding, blow molding, foam molding and the like. ..

The molded product made of the polyacetal resin composition of the present invention molded in this manner has its surface gloss sufficiently suppressed, and the degree of its surface gloss is determined by the measurement method (mirror surface) described in Examples described later. The glossiness due to (using a mold) is 35% or less, preferably 30% or less, and particularly preferably 25% or less.

Further, in the recent automobile field, in order to give the interior a luxurious feel and to improve the feel, most of the interior parts are textured, which are called leather grain and satin grain, and are mirrored. At the same time as lowering the gloss, it is necessary to have high transferability to the textured surface.

While ordinary polyacetal resins cannot meet such demands probably because of their high crystallinity, in the polyacetal composition of the present invention, the surface of the molded product is modified by the action of the compounding components, so that the surface of the molded product is modified. The transferability to the textured surface becomes very good, and the gloss on the textured surface is further reduced.

As the molded product of the present invention, a molded product that is molded using a mold in which a part or all of the inner surface of the mold is textured and has a textured shape in part or all of the surface is preferable. The graining of the inner surface of the mold can be performed by corrosion machining such as chemical etching, electric discharge machining, etc., and the surface roughness of the grain pattern can be selected according to the appearance of the target molded product.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. In addition, all "parts" in Examples and Comparative Examples represent parts by mass. In addition, various characteristics evaluated in Examples and Comparative Examples and their evaluation methods are as follows. The unit of the numerical value shown in Tables 1 and 2 is a mass part. The measurement was carried out in an atmosphere of 23 ° C. and 55% RH unless otherwise specified.

The various component ratios shown in Tables 1 and 2 were added and mixed, and melt-kneaded with a twin-screw extruder with a vent to prepare a pellet-shaped composition. The components shown in Tables 1 and 2 used in the examples are as follows.

(A) Polyacetal polymer A-1: Using a biaxial paddle type continuous polymerizer, 1,3-dioxolane 3.3% by mass and methylal 1000 ppm with respect to all the monomers (trioxane and 1,3-dioxolane). The added trioxane was continuously supplied, and at the same time, boron trifluorodibutyl etherate (catalyst concentration: 20 ppm (as boron trifluoride) cyclohexane solution for all monomers) was supplied to the same place for polymerization.
Immediately after the polymer discharged from the discharge port of the polymerizer, an aqueous solution containing 1000 ppm of triethylamine was added, mixed and pulverized, and stirred. Then, it was centrifuged and dried to obtain a catalyst-inactivated polymer. This polymer is supplied to a twin-screw extruder having a vent port, melt-kneaded at a resin temperature of about 220 ° C., and while devolatile under reduced pressure at the vent port, unstable ends are removed to form a pellet-shaped polymer. Got Then, it was dried to obtain a desired polymer. (Melt index (measured at 190 ° C. and load 2.16 kg): 9 g / 10 minutes)

A-2: Using a biaxial paddle type continuous polymerization machine, trioxane to which 1.3 mass% of 1,3-dioxolane and 1000 ppm of methylal were added to all the monomers (trioxane and 1,3-dioxolane) was continuously added. At the same time, phosphotungnic acid (catalyst concentration: 3 ppm methyl formate solution for all monomers) was supplied and polymerized as a heteropolyacid catalyst at the same place. 20 ppm of sodium stearate is added to the polymer discharged from the discharge port of the polymer, supplied to a twin-screw extruder having a vent port, melt-kneaded at a resin temperature of about 220 ° C., and devolatile under reduced pressure at the vent port. , The catalyst was deactivated and the unstable end was removed to obtain a pellet-shaped polymer. Then, it was dried to obtain a desired polymer. (Melt index (measured at 190 ° C. and load 2.16 kg): 9 g / 10 minutes)

(B) Hindered Phenolic Antioxidant B-1: Ethylene Bis (Oxyethylene) Bis [3- (3- (5-t-Butyl-4-hydroxy-m-trill) Propionate] (IRGANOX245: BASF) Made)
B-2: Pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (IRGANOX 1010: manufactured by BASF)
(C) Aliphatic carboxylic acid hydrazide C-1: Sebacic acid dihydrazide C-2: Adipic acid dihydrazide C-3: Dodecanedioic acid dihydrazide ・ (D) Hydantoin compound D-1: 1,3-bis (hydradinocarbo) Noethyl) -5-isopropyl hydantoin ("Amicure" VDH: manufactured by Ajinomoto Fine Techno Co., Ltd.)
(E) Alkaline earth metal salt of aliphatic carboxylic acid E-1: Calcium stearate E-2: 12-Calcium hydroxystearate

(F) Hindered amine compound F-1: 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β', β'-tetra Methyl-3,9- (2,4,8,10-tetraoxaspiro [5.5] undecane) Condensate with diethanol (ADEKA STAB LA-63P: manufactured by ADEKA Corporation)
F-2: Tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate (ADEKA STAB LA-52: manufactured by ADEKA Corporation)
F-3: Condensation of 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and tridecyl alcohol (ADEKA STAB LA-62: ADEKA Corporation) Made)
As described above, a hindered amine compound in which the nitrogen of a piperidine derivative having a steric hindrance group is tertiary F-4: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (TINUVIN770DF: manufactured by BASF) steric hindrance A hindered amine compound in which the nitrogen of a piperidine derivative having a sex group is secondary.

(G) UV absorber G-1: 2- (2H-benzotriazole-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (TINUVIN234: manufactured by BASF)
G-2: N- (2-ethylphenyl) -N'-(2-ethoxy-phenyl) oxalic acid diamide (SanduvorVSU: manufactured by Clariant AG)
(H) Core-shell polymer having a rubber-like polymer core and a glass-like polymer shell made of a vinyl-based copolymer H-1: Acrylic core-shell polymer (Staphyroid PO-0935: manufactured by Aika Kogyo Co., Ltd.)

<Evaluation>
The characteristic evaluation items and evaluation methods in the examples are as follows. The results are shown in Tables 3 and 4.

<Evaluation of formaldehyde generation (VOC) from molded products>
Using the polyacetal resin compositions prepared in Examples and Comparative Examples, a flat plate-shaped test piece (100 mm × 40 mm × 2 mmt) was molded under the following conditions. Two of these flat test pieces were enclosed in a 10 L polyvinyl fluoride sampling bag, degassed, 4 L of nitrogen was added, and heated at 65 ° C. for 2 hours, and then the nitrogen in the sampling bag was adjusted to 0.5 ml / min. 3 L was extracted, and the generated formaldehyde was adsorbed on a DNPH (2,4-dinitrophenylhydrazine) collecting tube (Sep-Pak DNPH-Silica: manufactured by Waters).

After that, the reaction product of DNPH and formaldehyde was extracted with acetonitrile from the DNPH collection tube, and the amount of formaldehyde generated was determined by a calibration curve method using a standard substance of the reaction product of DNPH and formaldehyde with a high-speed liquid chromatograph. , The amount of formaldehyde generated per unit mass of the test piece (μg / g) was calculated.

* Molding machine: FANUC ROBOSHOT α-S100ia (FANUC Co., Ltd.)
* Molding conditions: Cylinder temperature (° C) Nozzle-C1-C2-C3
190-190-180-160 ° C
Injection pressure 60 (MPa)
Injection speed 1.0 (m / min)
Mold temperature 80 (° C)

<Evaluation of Mold Deposit (MD)>
Using the polyacetal resin compositions prepared in Examples and Comparative Examples, a mold deposit test piece (33 mm × 23 mm × 1 mmt) was molded under the following conditions.
[Evaluation methods]
After 2000 shot continuous molding, the surface of the cavity in the mold was visually observed, and the amount of deposits was visually determined according to the following criteria.
⊚: No deposits are confirmed.
◯: Almost no deposits are confirmed.
Δ: Some deposits are confirmed.
X: Adhesion is confirmed on the whole.
XX: A large amount of deposits are confirmed throughout.

* Molding machine: FANUC ROBOSHOT S-2000i 50B (FANUC Co., Ltd.)
* Molding conditions: Cylinder temperature (° C) Nozzle-C1-C2-C3
205-215-205-185 ° C
Injection pressure 40 (MPa)
Injection speed 1.5 (m / min)
Mold temperature 80 (° C)

<Evaluation of weather resistance>
A flat molded product (70 mm x 40 mm x 3 mmt) is used for 800 hours under a fade condition of 83 ° C using a UV fade meter [UV autofade meter FAL-AU-HB / EM: manufactured by Suga Test Instruments Co., Ltd.]. After irradiation, it was taken out, and the presence or absence of cracks on the surface of the test piece and the change in hue (ΔE) before and after irradiation were examined by the following method.
-Presence or absence of cracks The surface of the test piece was visually observed to determine the presence or absence of cracks.
・ Change in hue (ΔE)
The hue (L *, a *, b *) of the molded product was measured with a Z-300A type color sensor manufactured by Nippon Denshoku Kogyo Co., Ltd., and the change in hue (ΔE) was calculated using the following formula.
ΔE = {(L * ₁ −L * ₀ ) ² + (a * ₁ −a * ₀ ) ² + (b * ₁ −b * ₀ ) ² } ^1/2
Note that L * ₀ , a * ₀ , and b * ₀ indicate the initial hue, and L * ₁ , a * ₁ , and b * ₁ indicate the hue after irradiation.

The smaller the value, the smaller the change in hue.

<Surface gloss>
The glossiness of the test piece molded with the mirror mold was measured at 45-45 degree reflection with a portable glossimeter (HG-246 manufactured by Suga Test Instruments Co., Ltd.) in accordance with the glossiness measurement of JIS-K7105. ..

As described above, it is clear that within the range of the composition of the present invention, it has excellent weather resistance, surface gloss is suppressed, and formaldehyde generation amount and mold deposit generation amount are also stably suppressed.

Claims (9)

At least 100 parts by mass of (A) polyacetal polymer,
(B) Hindered phenolic antioxidant 0.01 to 0.30 parts by mass,
(C) 0.01 to 0.50 parts by mass of aliphatic carboxylic acid hydrazide,
(D) 0.001 to 0.50 parts by mass of a hydantoin compound having two hydradinocarbonylalkyl groups,
(E) Alkaline earth metal salt of aliphatic carboxylic acid 0.001 to 0.30 parts by mass,
(F) Hindered amine compound 0.2 to 1.0 parts by mass,
(G) Ultraviolet absorber 0.2 to 1.0 parts by mass,
(H) 1 to 50 parts by mass of a core-shell polymer having a rubber-like polymer core and a glass-like polymer shell made of a vinyl-based copolymer.
And will contain
A polyacetal resin composition in which the total amount of (C) and (D) is 0.03 to 0.55 parts by mass with respect to 100 parts by mass of the (A) polyacetal polymer. The polyacetal resin composition according to claim 1, wherein the (F) hindered amine compound has a tertiary nitrogen of a piperidine derivative having a steric hindrance group. The polyacetal resin composition according to claim 1 or 2, wherein the (C) aliphatic carboxylic acid hydrazide is sebacic acid dihydrazide. The polyacetal resin composition according to any one of claims 1 to 3, wherein the alkaline earth metal salt of the (E) aliphatic carboxylic acid is at least one selected from calcium stearate and calcium 12-hydroxystearate. (D) The polyacetal resin composition according to any one of claims 1 to 4, wherein the hydantoin compound having two hydradinocarbonylalkyl groups is 1,3-bis (hydradinocarbonoethyl) -5-isopropylhydantoin. .. The (F) hindered amine compound is tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, 1,2,3,4-butanetetra. Carboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β', β'-tetramethyl-3,9- (2,4,8,10-tetraoxaspiro [5] .5] Undecane) At least one selected from a condensate with diethanol, a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol, claims 1 to 1. 5. The polyacetal resin composition according to any one of 5. The (G) UV absorbers are 2- (2H-benzotriazole-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol and N- (2-ethylphenyl) -N'. The polyacetal resin composition according to any one of claims 1 to 6, which is at least one selected from- (2-ethoxyphenyl) oxalic acid diamide. The polyacetal resin composition according to any one of claims 1 to 7, wherein the glassy polymer forming the shell of the core-shell polymer (H) is composed of a vinyl-based copolymer having an oxygen-containing polar group. The method for producing a polyacetal resin composition according to any one of claims 1 to 8, wherein the polyacetal polymer (A) has a trioxane as a main monomer (a) and has at least one carbon-carbon bond. And one or more selected from cyclic formal is used as a comonomer (b), copolymerized using a heteropolyacid as a polymerization catalyst (c), and then carbonates, hydrogen carbonates and carboxylic acids of alkali metals or alkaline earth metals. A method for producing a polyacetal resin composition, which is a polyacetal copolymer obtained by adding a salt or a hydrate (d) thereof, melt-kneading the mixture, and deactivating the polymerization catalyst (c).