KR100553396B1 - Polyoxymethylene Resin Composition for Speaker Grille of Automobile - Google Patents

Abstract

The present invention relates to a polyoxymethylene resin composition in which a polyoxymethylene resin contains a sorbitan pethiex ester, a polyalkylene glycol or an alkylene polyether-ester block copolymer, and the composition is required to have weather resistance and low light resistance. Molded products in the field and molded products requiring high flow characteristics, for example, speaker grills, air conditioner parts, various creep and buttons, automobile interior materials, machinery parts, electrical and electronic parts, office equipment such as computers, construction piping, sundries Very useful as a back material.

Description

Polyoxymethylene composition for speaker grille of vehicle

The present invention relates to a polyoxymethylene resin composition, and more particularly, it is exposed to light and has excellent color safety and matting, and flow characteristics for light, and is applied to an automobile speaker grill which is a complicated and long path injection product. It relates to a polyoxymethylene resin composition for a speaker grill suitable for.

Generally, polyoxymethylene resins (hereinafter referred to as "POM resins") have high mechanical strength and are excellent in rigidity, creep resistance, chemical resistance, and sliding properties. It has been widely used as a representative engineering resin in electric and electronic parts and industrial fields.

However, when a product molded from the conventional POM resin is used outdoors for a long time as it is, there is a problem in that the surface color changes and cracks occur due to the lack of weather resistance of the resin itself, and thus it is required to improve weather resistance. Especially when used as exterior products, discoloration of colors is more fatal than deterioration of physical properties. In addition, in the case of the exterior products that stand out easily, the effect of giving a luxurious and profound feeling by suppressing the gloss and the matteness of preventing the stimulation of the naked eye by suppressing the reflected light of sunlight are necessary.

In the case of the exterior product, the appearance is important, and appearance decoration is required, and thus the path of the molten resin is long during injection. In this case, high flow characteristics of the resin are required. However, when a low viscosity resin is used, there is a problem that the strength of the product is significantly lowered. A typical case is speaker grills used in automobiles. If a low viscosity high flow resin is used, the impact strength is insufficient and the product tends to be easily damaged. It is necessary to improve the flow characteristics by using a resin of mid viscosity rather than a resin of low viscosity.

The method of imparting low light property of the POM resin itself is a method of adding an acrylic polyphase interpolymer to the POM resin (Japanese Patent Laid-Open No. 59-136343), a rubber having a glass transition temperature of -20 ° C or lower. The method of mix | blending an elastic graft copolymer with a POM resin is known (Japanese Unexamined-Japanese-Patent No. 48-32830), and the method of adding the rubber-elastic graft copolymer which has butadiene group to a POM resin (Japanese Unexamined-Japanese-Patent No. 61-120849) is known. However, the composition obtained by the above method has a problem that the mechanical properties, in particular the strength and elastic modulus of the POM resin is greatly reduced, the thermal stability during molding is not sufficient. And a method of blending inorganic fillers such as calcium carbonate, calcium silicate, cray or talc with POM resin (Japanese Patent Laid-Open No. 64-54053) is known. However, the inorganic filler used in the known method is that the particle size is 5㎛ or more, there is a problem that the dispersibility and matte properties of the POM resin is significantly reduced.

In order to improve the weather resistance of the POM resin, a method of adding a weather stabilizer is well known. For example, there are a method of adding acrylic resin to POM resin (Japanese Patent Laid-Open No. 2-55756) and a method of adding carbon to POM resin (Japanese Patent Laid-Open No. 61-285240). However, both methods have a problem that the surface appearance and color of the POM resin is bad, and there is a problem of poor heat resistance.

A method of adding an infrared absorber, a hindered amine stabilizer, an aliphatic ester, and the like to a POM resin (Japanese Patent Laid-Open No. 61-47744, Japanese Patent Application Laid-Open No. 4-65862, Japanese Patent Application Laid-Open No. 5-48780) is also known. However, the POM resin prepared by the above known method is difficult to use in long-term outdoor use or in extreme conditions.

Accordingly, the present invention is to provide a polyoxymethylene resin composition suitable for a speaker grill in view of the above problems of the prior art as a technical problem.

In the present inventor's research for solving the above problems, the POM resin composition has a melt viscosity of 30 to 60 g / 10 minutes, more preferably 40 to 50 g / 10 minutes, surface glossiness of 20% or less, and the concentration of residual formaldehyde. Is less than 20 ppm, it is suitable as a material for speaker grills, which is specific to POM resins, such as sorbitan petiexide esters, triazine- and hindered phenol-based light stabilizers, polyoxyalkylene resins, inorganic fillers having a particle size of 5 μm or less; The present invention has been completed by knowing that it can be prepared by adding an aliphatic alcohol.

Therefore, according to the present invention, in the polyoxymethylene resin composition, (a) 100 parts by weight of polyoxymethylene resin, (b) 0.01-5 parts by weight of sorbitan pettiex ester, and (c) polyalkylene glycol or alkylene poly 0.1-5.0 parts by weight of ether-ester block copolymer, (d) 1.0-5.0 parts by weight of inorganic filler having a particle size of 5.0 μm or less, and (e) divalent aliphatic alcohol or low melting point polyamide resin having a melting point of less than 190 ° C. 0.01-5.0 There is provided a polyoxymethylene resin composition for a speaker grill of an automobile, comprising a weight part.

Further, according to the present invention, an automobile speaker grill, characterized in that the melt index is 30 to 60 g / 10 minutes, more preferably 40 to 50 g / 10 minutes, the surface glossiness is 20% or less, and the residual formaldehyde concentration is 20 ppm or less. A polyoxymethylene resin composition for is provided.

Hereinafter, the present invention will be described in more detail.

The composition contains, as a main component, a polyoxymethylene resin and an essential component, a sorbitan petiexide ester and a polyalkylene glycol or an alkylene polyether-ester block copolymer.

In the present composition, the main component of the POM resin is an oxymethylene homopolymer or an oxymethylene copolymer containing an oxyalkylene unit having at least one C 2 to 8 carbon atoms in a polymer main chain in which the main chain is an oxymethylene unit. Is preferred.

The oxymethylene homopolymer is preferably an oxymethylene homopolymer stabilized by substituting an unstable hydroxy group with an ester group or an ether group. Although not particularly limited, these oxymethylene homopolymers are polymerized by adding anhydrous formaldehyde in an organic solvent containing an organic amine, an organic or inorganic compound, a metal hydroxide and a basic polymerization catalyst, washing the polymer, and It can be prepared by acetylating the ends by heating in the presence.

Although not particularly limited, the oxymethylene copolymer is obtained by dissolving at least one of cyclic ether copolymerized with trioxane, a formaldehyde cyclic oligomer, in cyclohexane or benzene, and boron trifluoride, boron trifluoride hydrate, and boron trifluoride. And bulk polymerization in the presence of at least one polymerization catalyst selected from the group consisting of a coordination compound with an organic compound having an oxygen atom or a diboron atom. Here, the cyclic ether component, which is the copolymer, is premixed with a polymerization catalyst and then introduced into a self-cleaning stirrer, and a deactivator is added to remove catalytic activity from the polymer, and unstable end groups are decomposed and removed to obtain a polymer. Do.

In the present composition, the sorbitan petiexide ester is commercially available, and one example thereof is TECHLUBE, available from Tegnik Prodact Corporation of the United States. A preferable content of the sorbitan petiex ester in the present composition is 0.1 to 3 parts by weight, more preferably 0.3 to 2 parts by weight based on 100 parts by weight of the POM resin. If the content is less than 0.1 parts by weight, it is difficult to expect an improvement in the flow characteristics of the molten resin. If the content is more than 3 parts by weight, the improvement of the improvement effect is insignificant. However, there is a problem that the manufacturing cost is increased and economic efficiency is lowered.

In the present composition, the polyalkylene glycol serves to prevent cracks on the surface of the molded article, and the preferred content of the polyalkylene glycol in the present composition is 0.1 to 5 parts by weight based on 100 parts by weight of the POM resin. If the content is less than 0.1 parts by weight, the effect of addition is insignificant, and if it exceeds 5 parts by weight, there are problems such as deterioration of physical properties and generation of harmful gases during molding. Preferred polyalkylene glycols for use in the composition are polyethylene glycols having a molecular weight of 5,000 to 50,000. If the molecular weight of polyethylene glycol is less than 5000, it may transfer to the surface of the molded product after molding, which may cause whitening phenomenon, and moisture moisture absorption is easy, so that it is difficult to manage moisture of the resin, which is suitable because of the high possibility of generating a large amount of resin decomposition gas during molding. If it exceeds 50000, the flow characteristics of the resin are lowered, and the manufacturing cost is increased, which is economically undesirable.

In addition, the polyalkylene glycol requires attention to use as it causes a glare phenomenon on the surface of a molded article, and if an alkylene polyether-ester block copolymer is used instead of polyalkylene glycol, if a higher performance characteristic is required, It is possible. The alkylene polyether-ester block copolymer is a block copolymer including a hard segment composed of butylene terephthalate units and a soft segment composed of poly (ethylene oxide) terephthalate units. The dicarboxylic acid component constituting is composed of terephthalic acid alone, but 70 mol% or more of terephthalic acid alone, or more than 70 mol% of terephthalic acid and less than 30 mol% of isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, di 1 or 2 or more aromatic dicarboxylic acids, oxalic acid, succinic acid, adipic acid, azelic acid, sebacic acid, dodecanoic acid and dimer acid selected from the group consisting of phenyl-4,4'-dicarboxylic acid and 3-sulfonisophthalic acid It includes one or two or more alicyclic dicarboxylic acid selected from the group consisting of. Among these copolymerization components, preferably used are isophthalic acid, adipic acid, sebacic acid and dodecaic acid.

The diol component constituting the hard segment is mainly composed of 1,4-butadiol. That is, the diol component consists of 1,4-butadiol alone or 50% or more of 1,4-butadiol and 50 mol% or less of ethylene glycol, diethylene glycol, propylene glycol, 1,6-hexadiol, 1 And one or two or more copolymer components selected from the group consisting of, 10-decadidio, 1,4-dihydroxymethyl cyclohexane, bis (4-hydroxyethoxyphenyl) methane and neopentyl glycol.

The dicarboxylic acid component constituting the soft segment mainly consists of terephthalic acid. Like the dicarboxylic acid component of the hard segment, the dicarboxylic acid component of the soft segment is composed of terephthalic acid alone, or contains 70 mol% or more of terephthalic acid and 30 mol% or less of dicarboxylic acid as a copolymerization component. As the copolymerization component, mention may be made of dicarboxylic acids as exemplified above for the hard segments.

As the poly (ethylene oxide) glycol constituting the poly (ethylene oxide) terephthalate unit as the soft segment, poly (ethylene oxide) glycol having a number average molecular weight of 800 to 20,000 is used. Poly (ethylene oxide) glycols having a number average molecular weight of 5,000 to 15,000 are preferable, and those having a number average molecular weight of 8,000 to 10,000 are more preferable in view of compatibility with the POM resin. If the number average molecular weight is less than 800, the surface crack prevention effect is small, and if the number average molecular weight is greater than 20,000, compatibility with the butyl terephthalate unit of the hard segment is poor and a homogeneous polyether-ester block copolymer cannot be produced. .

In the polyether-ester block copolymer, a preferred composition ratio between the hard segment mainly composed of butylene terephthalate units and the soft segment mainly composed of poly (ethylene oxide) terephthalate units is selected from poly (poly (ethylene oxide) carboxylate unit). The content of the (ethylene oxide) carboxylate units is 40 to 85% by weight, more preferably 70 to 85% by weight. When the content of the poly (ethylene oxide) carboxylate unit is greater than 85% by weight, the polyether-ester block copolymer is difficult to polymerize and the mechanical strength of the composition is lowered.

The method for producing the polyether-ester block copolymer is not particularly important, and the polyether-ester block copolymer can be produced by a known conventional method. For example, a polyether-ester block copolymer may contain terephthalic acid (or dimethyl terephthalate) (a) and 1,4-butanediol (b) poly (ethylene oxide) glycol (c) in a reaction vessel equipped with a rectification column. It can be prepared according to the method of carrying out the esterification reaction or the transesterification reaction under atmospheric pressure or elevated pressure and then polymerizing under atmospheric pressure or reduced pressure. In addition, the polyether-ester block copolymers include terephthalic acid (or dimethyl terephthalate) (a) and 1,4-butanediol (b) poly (ethylene oxide) glycol

(c) may be added to the oligomer followed by polymerization under atmospheric or reduced pressure.

The present composition may contain, as an optional component, an inorganic filler, a benzotriazine-based and / or hindered amine-based light stabilizer, and a divalent aliphatic alcohol.

Preferred inorganic fillers are one or two or more selected from the group consisting of talc, cray, mica, wallastrite, asbestos, glass beads, etc. having a particle size of 5 μm or less, and in particular, amino silane coupling agents on the surface of some or all of the inorganic fillers. It is preferable to use the thing treated. Of these inorganic fillers, talc and cray are particularly preferred since they are excellent in surface matting when added to POM resin. Preferable content of the inorganic filler in this composition is 1-5 weight part with respect to 100 weight part of POM resin, More preferably, it is 2-4 weight part. If the content is less than 1 part by weight, low glossiness is insufficient, and if it exceeds 5 parts by weight, there is a problem that the mechanical strength, particularly impact strength is lowered.

As light stabilizer (E), 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] benzotriazyl, 2- (3,5-dibutyl-2-hydrophenyl) benzo Triazyl, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2- (2-hydroxy-benzotriazole- Benzotriazine-based light stabilizers such as 2-yl) -4,6-bis (1-ethyl-1-phenylethyl) phenol; 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2,2 ,

6,6-tetramethylpiperidine, 4-methoxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4- Cyclohexoxyoxy-2,2,6,6-titramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2,6 , 6-tetramethylpiperidine, 4- (pe

Nylcarbamooxy) -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 (2,2,6,6-tetramethyl 4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl Terephthalate, 1,2-bis (2,2,6,6-tetramethyl-4-piperidyloxy) ethane, bis (2,2,

6,6-tetramethyl-4-piperidyl) hexamethylene-1,6-dicarbamate, bis (1-mityl-2,2,6,

6-tetramethyl-4-piperidyl) adipate, tris (2,2,6,6-tetramethyl-4-piperidyl) benzene-1,3,5-tricarboxylate, pentaerythritol -Tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxy Hydroxyphenyl) propionate], 3,9-bis [1,1-dimethyl-2-β- (3-t-butyl-4-butyl-4-hydroxy-5methylphenyl) propionyloxy ethyl]- 2, 4, 8, 10-tetraoxaspiro [5,5] undecane-1, 3, 5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, Poly [(6-morpholino-S-triazine-2,4-dil) [2,2,6,6-tetramethyl-4-piperidyl] imino] -hexamethylene [(2,2, 6,6-tetramethyl-4-piperidyl) imino] and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate are preferably hindered amine light stabilizers. The above light stabilizers may be used alone or in combination of two or more, but it is preferable to use a benzotriazine light stabilizer and a hindered amine light stabilizer.

The addition amount of the light stabilizer in the present composition is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight based on 100 parts by weight of the POM resin. If the content is less than 0.01 part by weight, the light stability of the obtained composition is inferior, and when more than 5 parts by weight, a problem occurs that precipitates in the form of powder on the surface of the POM resin.

The dihydric aliphatic alcohol reacts with formaldehyde generated by thermal aging of the POM resin to prevent secondary decomposition caused from it, and also removes formaldehyde produced during the reaction by reacting to reduce the content of formaldehyde in the molded article. It is used to reduce the odor caused by lowering. Examples of the dihydric fatty acid alcohols mentioned above include dihydric fatty acid alcohols such as glyceryl mono stearate or pentaerythritol fetiside ester. It is also possible to use low melting point polyamide copolymers having a melting point of less than 190 ° C. instead of divalent fatty alcohols.

The preferable content of the dihydric aliphatic alcohol in this composition is 0.01-5.0 weight part with respect to 100 weight part of POM resin. If the content is less than 0.01 parts by weight, the addition effect is inferior, and if it exceeds 5 parts by weight, the physical properties are severely deteriorated and gas is generated.

In addition, the present composition may be blended with conventional additives well known in the art within a range that does not impair the object of the present invention.

The composition of the present invention described above has no major problem in producing a speaker grill at a melt index of 30 to 60 g / 10 minutes, particularly 40 to 50 g / 10 minutes, and the surface glossiness of molded articles molded from the resin. Is preferably 20% or less. Recently, as the internal parts of automobiles are refined, they are embossed to obtain satin-embossed processing or leather grain to improve the feel of most internal parts. Therefore, the embossed surface can remarkably lower the gloss by alleviating the surface of the POM resin. In addition, recently, various automobile companies have been evaluating the residual formaldehyde in the molded product because it causes odors. The evaluation related to the odor is usually performed by many people using the sense of smell. In the present invention, the amount of residual formaldehyde was evaluated by focusing on the fact that the amount of residual formaldehyde can be eliminated by reducing the amount of residual formaldehyde. In order to avoid the smell of formaldehyde in the molded article and the molding process, it was found that the evaluation result should be 20 ppm or less, thereby producing a resin composition having a concentration of 20 ppm or less in the molded article.

Features and other advantages of the present invention as described above will become more apparent from the following examples. However, the present invention is not limited to the following examples.

The evaluation method of the POM resin composition manufactured by this invention is as follows.

* Molding: Using an injection molding machine with an injection capacity of 60 tons, the cylinder temperature is set to 190 ° C, the mold temperature is 80 ° C, the molding cycle is set to 20 seconds, ASTM dumbbell test piece and a square plate of 80 × 80 × 3 mm thickness. Was injection molded.

* Weathering test: ASTM test specimen injection-molded in the above method in a weather-O-meter, and after 1000 hours treatment at 89 ℃, radish conditions, the color was measured, there was no crack Was visually observed at 24 hour intervals.

* Hue: The surface color after Fade-O-meter treatment was expressed as ΔE value using Minolta's Chroma Meter CR-200.

ΔE = (ΔL2 + Δa2 + Δb2) ^1/2

          (ΔL: change in brightness, Δa: change in red, Δb: change in yellow)

* Glossiness test of surface appearance: According to the method of measuring glossiness of JIS K7105, glossiness was measured at 45 ° -45 ° reflection with a 80 × 80 × 3 mm thick rectangular test plate injected by the above method with a digital optical system.

* Melt index: The prepared resin was dried at 85 ° C. for 4 hours and evaluated according to ASTM measurement.

* FA content: As the amount of formaldehyde (FA) remaining in the molded specimens, the molded product is left in a closed container for 30 minutes in a 140 ℃ oven and the amount of formaldehyde is quantified by gas chromatography.

* Crack occurrence: Observe surface crack occurrence for 1000 hours. "◎" is displayed when no surface crack occurs within the evaluation time of 1000 hours.

[Examples and Comparative Examples]

After drying the low-viscosity POM resin (using Kocetal K700 with a melt index of 27 g / 10 min: KTP Co., Ltd.) at 80 ° C. for 4 hours under vacuum, polyalkylene glycol as a light stabilizer, crack inhibitor, and sorbitan petiexide ester as a fluid enhancer After blending with dihydric fatty acid alcohol as formaldehyde and reactant, it is added to the first inlet of the twin screw extruder, and the inorganic filler is added to the second inlet. Fully melt kneaded at a temperature of 190 ° C. using a twin screw extruder. This is discharged to the spaghetti through the die, cooled, cut with a pelletizer and cut into chips. After drying the resin composition thus obtained well, various physical properties test specimens were injection molded at 190 ° C., and mechanical properties and weather resistance were evaluated. The compositions (based on 100 parts by weight of POM resin) of the polyoxymethylene resin compositions of Examples and Comparative Examples prepared as described above are shown in Table 1, and the evaluation results are shown in Table 2.

Light stabilizer (parts by weight) Crack Prevention Agent (parts by weight) Fluid Enhancer (parts by weight) Inorganic filler Formaldehyde reactants Example 1 E-1 (0.3) E-2 (0.1) 0.5 0.5 D-2 (0.5) F-2 (0.3) Comparative Example 1 E-1 (0.2) E-2 (0.3) 1.0 0 D-1 (1.0) F-1 (0.5) Example 2 E-1 (0.5) E-2 (0.2) 1.3 0.7 D-1 (2.0) F-2 (0.7) Comparative Example 2 E-1 (0.7) E-2 (0.3) 0 1.0 D-2 (1.0) F-2 (1.0) Example 3 E-1 (0.5) E-2 (0.2) 1.5 1.0 D-1 (1.0) F-2 (2.0) Comparative Example 3 E-1 (0.4) E-2 (0.3) 1.0 1.5 D-2 (1.5) 0 Comparative Example 4 0 1.0 1.0 D-1 (1.0) F-1 (1.0) Comparative Example 5 E-1 (0.3) E-2 (0.5) 1.0 1.0 0 F-2 (0.5)

* Light stabilizer

  E-1: 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol

  E-2: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate

* Inorganic filler

  D-1: Talc with an average particle size of 4 microns

  D-2: Cray with an average particle size of 4 microns

* Formaldehyde reactant

  F-1: Glyceryl Mono Fatty Acid Ester (Formula 1)

  F-2: pentaerythritol fatty acid ester (formula 2)

* Anti-crack agents use polyalkylene glycols with a molecular weight of 10,000.

Glossiness (%) Melt Index (g / 10min)  △ E (1000 hours) Crack occurrence time (hours) Formaldehyde (ppm) Example 1 17 45.7 15 ◎ 15 Comparative Example 1 11 29.7 8.1 ◎ 11 Example 2 7.8 53.5 11 ◎ 8.4 Comparative Example 2 10 51.4 6.7 240 7.7 Example 3 12 55.7 12 ◎ 6.2 Comparative Example 3 9.7 63.4 10 ◎ 74 Comparative Example 4 13 51.2 54 ◎ 7.6 Comparative Example 5 41 48.4 9.6 ◎ 13

As described above, the POM resin composition obtained by the present invention is a molded product in a field where weatherability and low light resistance are required and a molded product requiring high flow characteristics, for example, an automobile interior material such as a speaker grill, an air conditioner part, a mechanical part, It is very useful as a material for office equipment such as electric-electronic parts, computers, or construction piping, miscellaneous goods.

Claims (6)

In the polyoxymethylene resin composition, (a) 100 parts by weight of polyoxymethylene resin, (b) 0.01-5 parts by weight of sorbitan petiside ester, and (c) 0.1-5.0 parts by weight of polyalkylene glycol or alkylene polyether-ester block copolymer, ( d) 1.0 to 5.0 parts by weight of inorganic filler having a particle size of 5.0 μm or less and (e) a divalent aliphatic alcohol or 0.01 to 5.0 parts by weight of a low melting point polyamide resin having a melting point of less than 190 ° C. Polyoxymethylene resin composition. The polyoxymethylene resin composition for a speaker grill of an automobile according to claim 1, wherein the polyalkylene glycol is polyethylene glycol having a molecular weight of 5,000 to 50,000. delete delete In the polyoxymethylene resin composition, a melt index of 30 to 60 g / 10 minutes, surface glossiness (measured according to JIS K7105) less than 20%, residual formaldehyde concentration of 20 ppm or less for automobile grills of automobiles, characterized in that Polyoxymethylene resin composition. The polyoxymethylene resin composition for a speaker grill of an automobile according to claim 5, wherein a crack does not occur before 1,000 hours when the weather-o-meter is evaluated and the color difference (ΔE) is 1,000 or less after 1,000 hours. .