JP2013213146A - Polyacetal resin composition and molded product formed of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyacetal resin composition superior in matte properties and weatherability.SOLUTION: A polyacetal resin composition is obtained by: melting and kneading 100 pts.mass of a polyacetal resin (A) with 1-120 pts.mass of an aliphatic or alicyclic thermoplastic polyurethane (B), 0.01-10 pts.mass of an aliphatic or alicyclic isocyanate compound (C), and 0.01-5 pts.mass of a polyhydric alcohol (D) having three or more hydroxy groups in the molecule to obtain a molded product of a resin composition; and subsequently subjecting the molded product to heat treatment within 24 hours to promote a crosslinking reaction.

Description

  The present invention relates to a polyacetal resin composition and a molded article comprising the same. Specifically, the present invention relates to a polyacetal resin composition excellent in matteness of a molded product and excellent in weather resistance, and a molded product comprising the same.

  The polyacetal resin has an excellent balance of mechanical properties (friction resistance / abrasion resistance, creep resistance, dimensional stability, etc.) and has extremely excellent fatigue resistance. In addition, this resin is excellent in chemical resistance and has low water absorption. Therefore, polyacetal resin takes advantage of these characteristics, and as an engineering plastic, automotive interior parts, house interior parts (hot water mixing taps, etc.), clothing parts (fasteners, belt buckles, etc.), building materials applications (piping / pump parts) Etc.) and machine parts (gears, etc.) are widely used, and demand is growing.

However, polyacetal resin has better surface gloss than other resins and reflects light. For example, in applications such as automotive interior parts, it creates a sense of harmony with other materials and a high-class feeling. In addition, there are many cases where matte properties with low gloss are required.
There is a method of matting a molded product using a molding die whose surface is textured, but a sufficient matting effect cannot be obtained only by applying this to a polyacetal resin.

  A method of matting the polyacetal resin material itself has also been proposed in the past, and there is a method of adding an organic filler such as acrylic crosslinked particles to the polyacetal resin. There is a problem that the polyacetal resin is decomposed at the time of melt kneading with the polyacetal resin and at the time of molding, and the mechanical properties are likely to be lowered.

  Moreover, the method etc. which add inorganic fillers, such as a calcium carbonate and a talc, to a polyacetal resin are known (refer patent document 1). However, in this method, in order to obtain a desirable matting effect, it is necessary to add a large amount of an inorganic filler, which causes a decrease in mechanical properties such as elongation and toughness of the molded product. In addition, such inorganic fillers have the disadvantage of increasing the generation of formaldehyde in order to accelerate the decomposition of the polyacetal resin, which may cause contamination of the mold and deteriorate the working (hygienic) environment during the molding operation. There is a problem that there is.

In addition, a method of blending a core-shell polymer having a glassy polymer shell made of a vinyl copolymer having a rubber-like polymer core and an oxygen-containing polar group with a polyacetal resin has been proposed (see Patent Document 2). Thermal stability and matte properties are still insufficient.
Furthermore, the proposal (refer patent document 3) which improves a matte property by mix | blending an isocyanate compound is made | formed.
However, even in this proposal, the matting effect is not sufficient, and even if the matting effect is sufficient, the weather resistance is poor, and there is a defect that cracks occur at an early stage in the weather resistance test.

Japanese Patent Laid-Open No. 1-170641 JP-A-5-271361 JP-A-5-255570

Therefore, it has been desired to develop a polyacetal resin composition having low gloss, excellent matteness of molded products, and excellent weather resistance.
An object of the present invention is to provide a polyacetal resin composition having excellent matting properties and excellent weather resistance, and a resin molded product comprising the same.

The present inventors blended and melted an aliphatic or alicyclic thermoplastic polyurethane (B), an aliphatic or alicyclic isocyanate compound (C) and a specific polyhydric alcohol (D) into the polyacetal resin (A). The present inventors have found that a polyacetal resin composition obtained by reacting a composition obtained by kneading with a specific heat treatment has excellent matting properties and weather resistance, and has completed the present invention.
The present invention provides the following polyacetal resin composition and a molded product comprising the same.

[1] Aliphatic or alicyclic thermoplastic polyurethane (B) 1 to 120 parts by mass, aliphatic or alicyclic isocyanate compound (C) 0.01 to 10 parts by mass with respect to 100 parts by mass of the polyacetal resin (A). And 0.01 to 5 parts by mass of a polyhydric alcohol (D) having 3 or more hydroxyl groups in the molecule is melt-kneaded to obtain a molded product of the resin composition, and then the molded product is subjected to heat treatment within 24 hours. A polyacetal resin composition obtained by applying to accelerate a crosslinking reaction.
[2] The polyacetal resin composition as described in [1] above, wherein the heat treatment is performed at a temperature of 50 to 130 ° C. for 1 hour or more.
[3] A polyacetal resin composition comprising 1 to 120 parts by mass of the polyacetal resin composition according to the above [1] or [2] with respect to 100 parts by mass of the polyacetal resin (E).
[4] The polyacetal resin composition according to the above [3], further comprising 0.01 to 5 parts by mass of the ultraviolet absorber (F) with respect to 100 parts by mass of the polyacetal resin (E).
[5] The above [3] or [4], further comprising 0.01 to 5 parts by mass of the hindered amine light stabilizer (G) with respect to 100 parts by mass of the polyacetal resin (E). Polyacetal resin composition.
[6] A molded product formed by molding the polyacetal resin composition according to any one of [1] to [5].

The polyacetal resin composition of the present invention is excellent in matteness of a molded product, the molded product is excellent in high-class feeling, and excellent in weather resistance. Furthermore, when a UV absorber or a hindered amine light stabilizer is blended, the weather resistance can be further effectively improved.
Therefore, the molded product formed by molding the polyacetal resin composition of the present invention can be suitably used for automobile interior parts, interior parts such as houses, and the like.

[1. Summary of the Invention]
The polyacetal resin composition of the present invention is an aliphatic or alicyclic thermoplastic polyurethane (B) 1 to 120 parts by mass, an aliphatic or alicyclic isocyanate compound (C) 0 with respect to 100 parts by mass of the polyacetal resin (A). 0.01 to 5 parts by mass and 0.01 to 5 parts by mass of a polyhydric alcohol (D) having 3 or more hydroxyl groups in the molecule to obtain a molded resin composition, and then within 24 hours, The molded product is obtained by subjecting it to a heat treatment to promote a crosslinking reaction.
The matteness of the polyacetal resin uses the light irregular reflection effect due to the unevenness on the molding surface, but the conventional matting agent described above tends to be exposed too much on the molding surface, and it is difficult to obtain sufficient irregular reflection. . In the present invention, by adopting the above-described configuration, the polyurethane cross-linked particles are raised on the molding surface in a state in which the polyurethane cross-linked particles are sufficiently blended with each other, so that a favorable uneven surface can be formed and an excellent matting effect is achieved. be able to. Furthermore, the product thus obtained is extremely stable against ultraviolet rays compared to the case of using an aromatic thermoplastic polyurethane as the thermoplastic polyurethane or the case of using an aromatic isocyanate compound as the isocyanate compound. And has excellent weather resistance.

Hereinafter, the contents of the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples.
In the specification of the present application, “to” is used in the sense of including the numerical values described before and after it as lower and upper limits.

[2. Polyacetal resin (A)]
The polyacetal resin (A) used in the present invention is a polymer having a repeating acetal structure represented by-(-O-CRH-) _n- (wherein R represents a hydrogen atom or an organic group). Has an oxymethylene group (—CH ₂ O—) in which R is a hydrogen atom as a main structural unit. The polyacetal resin (A) used in the present invention may be a copolymer (block copolymer) or terpolymer containing a constituent unit other than the oxymethylene unit in addition to the homopolymer consisting of only the oxymethylene unit, It may have a branched structure or a crosslinked structure as well as the shape structure.

As structural units other than the oxymethylene unit, an oxyethylene group (—CH ₂ CH ₂ O—), an oxypropylene group (—CH ₂ CH ₂ CH ₂ O—), an oxybutylene group (—CH ₂ CH ₂ CH ₂ CH). _{And an} optionally branched oxyalkylene group such as ₂ O—). Among these, an oxyalkylene group having 2 to 4 carbon atoms which may be branched is preferable, and an oxyethylene group is particularly preferable. The content of oxyalkylene groups other than oxymethylene groups in the polyacetal resin is usually 0.1 to 20% by mass.

The manufacturing method of a polyacetal resin (A) is well-known, In this invention, the polyacetal resin manufactured by any method can also be used.
For example, as a method for producing a polyacetal resin having an oxymethylene group and an oxyalkylene group having 2 to 4 carbon atoms as structural units, an oxymethylene group such as formaldehyde trimer (trioxane) or tetramer (tetraoxane) is used. Produced by copolymerizing a cyclic oligomer and a cyclic oligomer containing an oxyalkylene group having 2 to 4 carbon atoms such as ethylene oxide, 1,3-dioxolane, 1,3,6-trioxocan, 1,3-dioxepane. be able to. As the polyacetal resin, it is preferable to use a copolymer of a cyclic oligomer such as trioxane or tetraoxane and ethylene oxide or 1,3-dioxolane, and it is particularly preferable to use a copolymer of trioxane and 1,3-dioxolane. preferable.

As the polyacetal resin (A), those having an appropriate hydroxyl group terminal among all terminal groups are preferable, and those having a hydroxyl group terminal of 50 to 100 mol%, more preferably 70 to 100 mol%, based on the entire terminal group. It is preferable to use it. Moreover, the ratio of the terminal hydroxyl group to the whole terminal group can be adjusted with the usage-amount of the water at the time of superposition | polymerization, or a polyhydric alcohol.
Further, the polyacetal resin (A) has a melt index (ASTM-D1238 standard: 190 ° C., 2.16 Kg) of usually 1 to 100 g / 10 minutes, preferably 0.5 to 80 g / 10 minutes.

[3. Aliphatic or alicyclic thermoplastic polyurethane (B)]
The aliphatic or alicyclic thermoplastic polyurethane (B) includes an aliphatic or alicyclic polyisocyanate compound, a polyol having two or more hydroxyl groups, and, if desired, a molecular structure produced using a chain extender. It means a polyurethane elastomer having a urethane bond inside. The thermoplastic polyurethane can be produced according to a known method, in other words, according to a known urethanization reaction technique. In general, the ratio of the isocyanate group to the hydroxyl group is selected in the range of 0.5 to 2, more preferably in the range of 0.9 to 1.5.

Preferred examples of the aliphatic polyisocyanate compound constituting the thermoplastic polyurethane (B) include 1,6-hexamethylene diisocyanate, tetramethylene diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate. Examples of the alicyclic polyisocyanate compound include isophorone diisocyanate, 4,4′-methylene-bis- (cyclohexyl isocyanate), 1,3-bis- (isocyanate methyl) cyclohexane, 1,4-bis- (isocyanate methyl). A cyclohexane etc. are mentioned preferably. These may be used alone or in admixture of two or more.
Of these, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 1,3-bis- (isocyanate methyl) cyclohexane, and 4,4′-methylene-bis- (cyclohexyl isocyanate) are particularly preferable.

The aliphatic or alicyclic polyisocyanate compound constituting the thermoplastic polyurethane (B) is used in combination with a small amount of the aromatic polyisocyanate compound, for example, up to 5 molar equivalent% within the range not impairing the effects of the present invention. May be.
Such aromatic polyisocyanate compounds include m- or p-phenylene diisocyanate, m- or p-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4 , 4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate and the like.

  In addition, the polyol constituting the thermoplastic polyurethane (B) is not particularly limited as long as it is a compound having two or more hydroxyl groups, but preferred examples include polyether polyols, polyether ester polyols, polyester polyols, and polycarbonate polyols. More preferred are polyether diols, polyether diols, polyester diols, polycarbonate diols having a hydroxyl group at the end of the molecular structure. Two or more of these polyols may be mixed and used. The number average molecular weight of the polyol is preferably 500 to 5,000, more preferably 1,000 to 3,000.

  Here, examples of the polyether diol include polymers derived from alkane diols having 2 to 12 carbon atoms such as polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyethylene oxide, and polypropylene oxide. Polymers derived from C2-C12 cyclic ethers such as polytetrahydrofuran are preferably used.

  The polyether ester diol means one obtained by polymerizing polyether diol, dicarboxylic acid anhydride and cyclic ether. As the polyether diol, the above-mentioned polyether diol is used. As the dicarboxylic acid anhydride, phthalic anhydride, maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, etc. are used. As the cyclic ether, ethylene oxide, propylene oxide, tetrahydrofuran are used. Etc. are included.

  The polyester diol means one polymerized from a dihydric alcohol and a dicarboxylic acid, or a polylactone diol. Dihydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol C2-C12 alkanediols such as neopentyl glycol, 2-methylpropanediol, 2-methyl-1,8-octanediol, nonanediol, 1,10-decanediol, succinic acid C 4-12 aliphatic or aromatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, maleic acid, terephthalic acid and isophthalic acid are preferably used. As the polylactone diol, polycaprolactone glycol, polypropiolactone glycol, polyvalerolactone glycol and the like are preferably used.

  The polycarbonate diol means one obtained by polymerizing the above dihydric alcohol and diphenyl carbonate or phosgene.

  As the chain extender, aliphatic, alicyclic, aromatic diol or diamine is used. Examples of the diol include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanediol. Hydroquinone diethylol ether, 1,4-bishydroxyethylbenzene, resorcin diethylol ether, hydrogenated bisphenol-A, or derivatives thereof are used. As the diamine, hydrazine, ethylenediamine, hexamethylenediamine, xylylenediamine, 1,4-diaminodiphenylmethane, or derivatives thereof are used. The molecular weight of the chain extender is preferably 500 or less.

  The compounding quantity of an aliphatic or alicyclic thermoplastic polyurethane (B) is 1-120 mass parts with respect to 100 mass parts of polyacetal resin (A). If it is less than 1 part by mass, the effect of improving matting properties is insufficient, and if it exceeds 120 parts by mass, the mechanical properties of the polyacetal resin composition are impaired. Preferably it is 3-100 mass parts, More preferably, it is 5-80 mass parts.

[3. Aliphatic or alicyclic isocyanate compound (C)]
As the aliphatic or alicyclic isocyanate compound (C) used in the polyacetal resin composition of the present invention, an aliphatic or alicyclic diisocyanate compound is used.
Preferred examples of the aliphatic diisocyanate include 1,6-hexamethylene diisocyanate, tetramethylene diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate. Examples of the alicyclic diisocyanate include isophorone diisocyanate. 4,4′-methylene-bis- (cyclohexyl isocyanate), 1,3-bis- (isocyanatomethyl) cyclohexane, 1,4-bis- (isocyanatomethyl) cyclohexane and the like are preferable. Dimers, trimers of these isocyanate compounds, carbodiimide-modified products of these isocyanate compounds, prepolymers of these isocyanate compounds and polyhydric alcohols, and these isocyanate compounds are blocked with blocking agents such as phenol, primary alcohol and caprolactam. It may be a blocked isocyanate compound.

Of the isocyanate compounds, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 1,3-bis- (isocyanatomethyl) cyclohexane, and 4,4′-methylene-bis- (cyclohexyl isocyanate) are particularly preferable.
In addition, you may use the thing melt-mixed with the polyacetal resin (A) or the thermoplastic polyurethane (B) previously as an isocyanate compound.

  The compounding quantity of an aliphatic or alicyclic isocyanate compound (C) is 0.01-10 mass parts with respect to 100 mass parts of polyacetal resin (A). If the amount is less than 0.01 parts by mass, a sufficient matting effect cannot be obtained. If the amount exceeds 10 parts by mass, not only the mechanical properties of the polyacetal resin composition are impaired, but also the isocyanate compound remains excessively in the resin composition. It becomes difficult to use. Preferably it is 0.1-5 mass parts, More preferably, it is 0.5-3 mass parts.

[4. Polyhydric alcohol having three or more hydroxyl groups in the molecule (D)]
Examples of the polyhydric alcohol (D) having 3 or more hydroxyl groups in the molecule include pentaerythritol, glycerin, trimethylolethane, trimethylolpropane, hexanetriol, diglycerin, methyl glucoside, aromatic diamine-tetraethanol adduct, sorbitol. Dipentaerythritol, cyclodextrin, sucrose and the like are preferable. As the polyhydric alcohol, a high molecular compound or oligomer compound having three or more hydroxyl groups in the molecule such as phenoxy resin, polyhydroxyethyl methacrylate, or polyvinyl alcohol can also be selected. The polyhydric alcohol (D) is preferably a trivalent or tetravalent polyhydric alcohol.
These polyhydric alcohols may be used alone, or two or more kinds may be selected and used as a mixture in an appropriate ratio. In addition, this polyhydric alcohol can use what was previously melt-mixed with the polyacetal resin (A) or the thermoplastic polyurethane (B).

  The compounding quantity of the polyhydric alcohol (D) which has a 3 or more hydroxyl group in a molecule | numerator is 0.01-5 mass parts with respect to 100 mass parts of polyacetal resin (A). If the amount is less than 0.01 parts by mass, a sufficient matting effect cannot be obtained. If the amount exceeds 5 parts by mass, not only the mechanical properties of the polyacetal resin composition are impaired, but also the polyhydric alcohol is excessive in the resin composition. This makes it difficult to use. Preferably it is 0.05-3 mass parts, More preferably, it is 0.1-1.5 mass parts.

The blending ratio of each of the above components is preferably (component (A) / component (B) / component (C) / component (D) = 40 when the total of components (A) to (D) is 100 mass%. -99 / 1-60 / 0.01-10 / 0.01-5 mass%, More preferably, component (A) / component (B) / component (C) / component (D) = 70-90 / It is 5-25 / 0.1-2 / 0.1-1 mass%. By setting it as such a ratio, the matte effect can be made more excellent, without a mechanical physical property falling.
Moreover, it is preferable to mix | blend a thermoplastic polyurethane (B) and an isocyanate compound (C) so that the isocyanate equivalent may become an excess with respect to the active hydrogen which a component (A) and a component (D) have.

[5. Other ingredients]
The polyacetal resin composition of the present invention can contain any resin additive within a range not impairing the effects of the present invention.
For example, for the purpose of improving the weather resistance of a polyacetal resin composition, UV absorbers such as benzotriazole compounds, benzophenone compounds, aromatic benzoate compounds, cyanoacrylate compounds, and oxalic acid anilide compounds, and light such as hindered amine compounds. One or more stabilizers can be included. The preferable content of these components is 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, and further preferably 0.03 to 2 parts by mass with respect to 100 parts by mass of the polyacetal resin (A). Part. If the content is less than 0.01 parts by mass, sufficient weather resistance is difficult to obtain, and if it exceeds 5 parts by mass, the mechanical properties of the resulting resin composition tend to be lowered.

  For the purpose of suppressing the generation of formaldehyde, for example, amide compounds, amino-substituted triazine compounds, adducts of amino-substituted triazine compounds and formaldehyde, condensates of amino-substituted triazine compounds and formaldehyde, urea, urea derivatives, imidazole compounds, imides It is also possible to contain one or more stabilizers containing formaldehyde-reactive nitrogen such as compounds and hydrazine derivatives. The content of these components is preferably 0.01 to 1 part by mass, more preferably 0.03 to 0.3 part by mass, and still more preferably 0.05 to 0, relative to 100 parts by mass of the polyacetal resin (A). 15 parts by mass. If the content is less than 0.01 parts by mass, the effect of reducing the generation of formaldehyde from the molded product may be insufficient. Conversely, if the content exceeds 1 part by mass, the amount of mold deposits at the time of injection molding will increase and molding will occur. It is easy to be unable to perform efficiently.

  Further, an alkali metal or alkaline earth metal hydroxide, inorganic acid salt, alkoxide or the like may be contained. For example, hydroxides such as sodium, potassium, calcium and magnesium, inorganic acid salts such as carbonates, phosphates, silicates and borates, and alkoxides such as methoxide and ethoxide can be blended. In particular, an alkaline earth metal compound is preferably blended, and calcium hydroxide, magnesium hydroxide, calcium carbonate, or magnesium carbonate is particularly blended. When mix | blending an alkaline-earth metal compound, Preferably it is 1 mass part or less with respect to 100 mass parts of polyacetal resin (A), More preferably, it is made to contain in the ratio of 0.5 mass part or less.

Moreover, you may mix | blend a well-known various additive and filler in the polyacetal resin composition of this invention within the range which does not impair the objective of this invention other than said component.
Examples of the additives include antioxidants, lubricants, nucleating agents, mold release agents, plasticizers, antistatic agents, flame retardants, and the like, and fillers include glass fibers, glass flakes, glass beads, talc, Examples include mica and potassium titanate whiskers.

[6. Method for producing molded product of resin composition]
In order to produce a molded product of the resin composition from the above component (A), component (B), component (C) and component (D), predetermined amounts of these components are blended simultaneously or in any order, and desired Further, other additives and the like can be blended and then melt-kneaded and reacted. The melt kneading can be performed at a temperature of preferably about 180 to 260 ° C, more preferably about 190 to 220 ° C.
Melt kneading can be carried out by any method such as a continuous type and a batch type, and can be performed using a known apparatus, for example, a melt kneader such as a kneader, a single screw or a twin screw extruder.

  As specific examples of the melt-kneading apparatus, a single-screw extruder, a meshing-type co-rotating twin-screw extruder, a meshing-type counter-rotating twin-screw extruder, a non-incomplete meshing-type counter-rotating twin-screw extruder, etc. are preferable. It can be illustrated. The time of melt shear mixing depends on the resin temperature in the apparatus and the shear mixing force of the apparatus, and thus cannot be generally defined, but is usually in the range of 1 second to 30 minutes.

The resin composition that has undergone the reaction and fine dispersion after being melt-kneaded is extruded by a melt-kneader such as an extruder to obtain a preliminary molded product of the resin composition. Usually, it is extruded into a strand shape, and this is pelletized by a pelletizer or the like.
Next, the molded product is subjected to a heat treatment to promote a crosslinking reaction. The heat treatment needs to be performed within 24 hours after the formation of a pre-formed product such as a pellet. By performing such a heat treatment, a resin composition that satisfies both the matteness and weather resistance can be obtained. When the heat treatment is performed after 24 hours after molding, the gloss does not become low gloss and good matte properties cannot be obtained.

  The temperature range of the heat treatment is preferably a temperature range of 50 to 130 ° C. More preferably, it is 60-120 degreeC, More preferably, it is 70-110 degreeC, Especially 80-100 degreeC. About the time of heat processing, it is 1 hour or more, More preferably, it is 2 hours or more, More preferably, it is 3 hours or more, Most preferably, it is 4 hours or more, and an upper limit is about 24 hours.

  The atmosphere during the heat treatment is preferably air, nitrogen, an inert gas, a gas that is inert with respect to polyacetal resin, thermoplastic polyurethane, etc., but is preferably in a dry state with low humidity. Dry air is preferred. Moreover, it is also preferable to carry out under pressure in order to suppress mixing of moisture during heat treatment.

  Examples of the heat treatment apparatus used for the heat treatment include a stationary dryer, a rotary dryer, a fluidized bed dryer, and a dryer having a stirring blade. As a heat treatment method, a heat treatment method at a constant temperature, a heat treatment method in which the temperature is raised continuously or at a temperature of at least two steps or more can be adopted.

  In the present invention, a molded product of the polyacetal resin composition melt-kneaded and heat-treated by the above method is used as a matting agent masterbatch to obtain a resin composition diluted with a polyacetal resin (E). You may use for a shaping | molding process. In addition, when the molded product of the polyacetal resin composition of the present invention that has been heat-treated is diluted with the polyacetal resin (E) and used, it is preferably diluted in the following manner.

[7. Polyacetal resin (E)]
The polyacetal resin (E) used for dilution is a polymer having a repeating acetal structure represented by-(-O-CRH-) _n- (where R represents a hydrogen atom or an organic group). The main structural unit is an oxymethylene group (—CH ₂ O—) in which R is a hydrogen atom. The polyacetal resin (E) used in the present invention may be a copolymer (block copolymer) or a terpolymer containing a constituent unit other than the oxymethylene unit in addition to the homopolymer consisting of only the oxymethylene unit, It may have a branched structure or a crosslinked structure as well as the shape structure.
As structural units other than the oxymethylene unit, an oxyethylene group (—CH ₂ CH ₂ O—), an oxypropylene group (—CH ₂ CH ₂ CH ₂ O—), an oxybutylene group (—CH ₂ CH ₂ CH ₂ CH). _{And an} optionally branched oxyalkylene group such as ₂ O—). Among these, an oxyalkylene group having 2 to 4 carbon atoms which may be branched is preferable, and an oxyethylene group is particularly preferable. The content of oxyalkylene groups other than oxymethylene groups in the polyacetal resin is usually 0.1 to 20% by mass.

The manufacturing method of a polyacetal resin (E) is well-known, In this invention, the polyacetal resin manufactured by any method can also be used.
For example, as a method for producing a polyacetal resin having an oxymethylene group and an oxyalkylene group having 2 to 4 carbon atoms as structural units, an oxymethylene group such as formaldehyde trimer (trioxane) or tetramer (tetraoxane) is used. Produced by copolymerizing a cyclic oligomer and a cyclic oligomer containing an oxyalkylene group having 2 to 4 carbon atoms such as ethylene oxide, 1,3-dioxolane, 1,3,6-trioxocan, 1,3-dioxepane. be able to. As the polyacetal resin, it is preferable to use a copolymer of a cyclic oligomer such as trioxane or tetraoxane and ethylene oxide or 1,3-dioxolane, and it is particularly preferable to use a copolymer of trioxane and 1,3-dioxolane. preferable.
The melt index (ASTM-D1238 standard: 190 ° C., 2.16 Kg) of the polyacetal resin (E) is usually 1 to 100 g / 10 minutes, but preferably 0.5 to 80 g / 10 minutes.

  When the molded product of the polyacetal resin composition of the present invention is used after being diluted with the polyacetal resin (E), the dilution ratio is 100 parts by mass of the polyacetal resin (E) obtained by heat-treating the polyacetal resin composition. It is preferable to use it in the ratio of 1-120 mass parts with respect to it. When the dilution ratio is less than 1 part by mass, it is difficult to obtain sufficient matting properties, and when it exceeds 120 parts by mass, the mechanical properties of the resulting polyacetal resin composition may be impaired. A more preferable dilution ratio is 5 to 110 parts by mass, and further preferably 10 to 105 parts by mass with respect to 100 parts by mass of the polyacetal resin (E).

[8. UV absorber (F)]
When the molded product of the polyacetal resin composition of the present invention is used after being diluted with the polyacetal resin (E), it is preferable to incorporate an ultraviolet absorber (F) in order to improve the weather resistance of the resulting resin composition.
The ultraviolet absorber (F) used in the present invention is a compound having an action of absorbing ultraviolet rays. Preferably, it is selected from benzotriazole compounds, benzophenone compounds, aromatic benzoate compounds, cyanoacrylate compounds, and oxalic anilide ultraviolet absorbers. Two or more of these compounds may be used in combination.

As a specific example of the ultraviolet absorber (F),
2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole,
2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol],
2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol,
2- (2′-hydroxy-3 ′, 5′-di-isoamyl-phenyl) benzotriazole,
2- [2′-hydroxy-3 ′, 5′-bis- (α, α-dimethylbenzyl) phenyl] benzotriazole,
2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole,
2,4-dihydroxybenzophenone,
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-oxybenzylbenzophenone,
2-hydroxy-4-methoxy-5-sulfobenzophenone,
pt-butylphenyl salicylate,
p-octylphenyl salicylate,
2-ethylhexyl-2-cyano-3,3′-diphenyl acrylate,
Ethyl-2-cyano-3,3′-diphenyl acrylate,
N- (2-ethoxy-5-t-butylphenyl) oxalic acid diamide,
N- (2-ethylphenyl) -N ′-(2-ethoxyphenyl) oxalic acid diamide and the like can be mentioned.

These ultraviolet absorbers (F) may be used alone or in combination of two or more.
A preferred ultraviolet absorber (F) is a benzotriazole ultraviolet absorber, and particularly preferably a benzotriazole ultraviolet absorber having a vapor pressure at 20 ° C. of 1 × 10 ⁻⁸ Pa or less.
Specifically, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol,
2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol].

The preferable content of the ultraviolet absorber (F) is 0.01 to 5 parts by mass with respect to 100 parts by mass of the polyacetal resin (E). If the content is less than 0.01 parts by mass, sufficient weather resistance is difficult to obtain, and if it exceeds 5 parts by mass, the mechanical properties are likely to be significantly deteriorated. The preferable content of the ultraviolet absorber is 0.01 to 3 parts by mass, and more preferably 0.03 to 2 parts by mass.
When the molded product of the polyacetal resin composition of the present invention is used after being diluted with the polyacetal resin (E), excellent thermal stability can be obtained by including an ultraviolet absorber (F) and a hindered amine light stabilizer (G) described later. In addition to the properties, moldability and formaldehyde generation suppression effect, the weather resistance of pellets and molded products can be improved.

[9. Hindered amine light stabilizer (G)]
When the molded product of the polyacetal resin composition of the present invention is diluted with the polyacetal resin (E) and used, in order to improve the weather resistance of the resulting resin composition, one or more hindered amine light stabilizers (G) are used. It is preferable to mix.
The hindered amine light stabilizer is an amine having a piperidine structure represented by the following general formula (1).

In the general formula (1), X represents an organic group in which the bond to the nitrogen atom is a carbon atom, and Y represents an organic group or a hydrogen atom bonded to the piperidyl group via an oxygen atom or a nitrogen atom.
Preferable X includes an alkyl group having 1 to 10 carbon atoms. When X is an alkyl group, for example, a linear or branched alkyl group having 1 to 10 carbon atoms such as methyl group, ethyl group, propyl group, t-butyl group, hexyl group, octyl group, decyl group and the like can be mentioned. A methyl group is particularly preferable. Further, the hindered amine light stabilizer can have a plurality of piperidine structures in the molecule, but all the piperidine structures have an N-carbon atom-2,2,6,6-tetramethyl-4-piperidyl structure. Preferably there is.

Specific examples of the preferred hindered amine light stabilizer (G) include the following compounds.
Bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate 1- [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4 -[3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidinetetrakis (1,2,2,6,6-pentamethyl-4 -Piperidyl) -1,2,3,4-butanetetracarboxylate 1,2,2,6,6-pentamethyl-4-piperidyl and tridecyl-1,2,3,4 butanetetracarboxylate (butanetetracarboxylate) A mixture of compounds in which some of the four ester moieties are 1,2,2,6,6-pentamethyl-4-piperidyl and the others are tridecyl)
1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β, β-tetramethyl-3,9 (2,4,8, Condensate of 10-tetraoxaspiro [5,5] udencan) -diethanol Condensate of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol 1,2,2, 6,6-pentamethyl-4-piperidyl methacrylate N, N ′, N ″, N ′ ″-tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-tetra Methylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diaminebis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5 -Bis (1,1 dimethylethyl) -4 Hydroxyphenyl] methyl] butyl malonate

  The preferable content of the hindered amine light stabilizer (G) is 0.01 to 5 parts by mass with respect to 100 parts by mass of the polyacetal resin (E). If the content is less than 0.01 parts by mass, sufficient weather resistance (cracking time delay effect) is difficult to obtain, and if it exceeds 5 parts by mass, mechanical properties are significantly deteriorated and mold contamination tends to increase. The more preferable content of the hindered amine light stabilizer (G) is 0.01 to 3 parts by mass, and more preferably 0.03 to 2 parts by mass.

[10. Stabilizers containing formaldehyde-reactive nitrogen (H)]
When the molded product of the polyacetal resin composition of the present invention is diluted with the polyacetal resin (E) and used, a stabilizer containing formaldehyde-reactive nitrogen (H for the purpose of suppressing the generation of formaldehyde from the resulting resin composition (H It is also preferable to blend.
Examples of stabilizers containing formaldehyde reactive nitrogen include amide compounds, polyamide resins, amino substituted triazine compounds, adducts of amino substituted triazine compounds and formaldehyde, condensates of amino substituted triazine compounds and formaldehyde, urea, urea derivatives, imidazole Examples thereof include compounds, imide compounds, and hydrazine derivatives. Two or more of these compounds may be used in combination.

  Specific examples of the amide compound include polycarboxylic acid amides such as isophthalic acid diamide and anthranilamides.

As the polyamide resin, any of an aliphatic polyamide resin, an alicyclic polyamide resin, and an aromatic polyamide resin can be used.
The polyamide resin may be composed of one type of structural unit or may be composed of a plurality of types of structural units.
The raw material of the polyamide resin is ω-amino acid, preferably linear ω-amino acid having 6 to 12 carbon atoms and lactam thereof; adipic acid, sebacic acid, dodecanedicarboxylic acid, heptadecanedicarboxylic acid, isophthalic acid, terephthalic acid, etc. Dicarboxylic acids and dimethyl esters thereof; diamines such as hexamethylenediamine. In the case of a copolymerized polyamide comprising a plurality of types of structural units, the copolymerization ratio, copolymerization form (random copolymer, block copolymer, cross-linked polymer) and the like can be arbitrarily selected.
In the present invention, it is preferable to use polyamide 12, polyamide 6/12 copolymer, polyamide 6/66/610 copolymer, polyamide 6/66/610/12 copolymer or the like as the polyamide resin.

  The amino-substituted triazine compound is an amino-substituted triazine having a structure represented by the following general formula (2), or an initial polycondensate of this with formaldehyde.

In the general formula (2), R ¹ , R ² and R ³ may each independently be substituted with a hydrogen atom, a halogen atom, a hydroxyl group, a mercapto group, an alkyl group having 1 to 10 carbon atoms, or an alkyl group. A good aryl group having 6 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an optionally substituted amino group is shown, but at least one of R ^{1 to} R ³ may be substituted. An amino group is shown.

  Specific examples of the amino-substituted triazine compound include, for example, guanamine, melamine, N-butylmelamine, N-butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N, N-diallylmelamine, N, N ′, N ″ -Triphenylmelamine, N, N ′, N ″ -trimethylolmelamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), 2,4-diamino-sym-triazine, acetoguanamine ( 2,4-diamino-6-methyl-sym-triazine), 2,4,6-triamino-sym-triazine, 2,4-diamino-6-butyl-sym-triazine, 2,4-diamino-6-benzyl Oxy-sym-triazine, 2,4-diamino-6-butoxy-sym-triazine, 2,4-dia No-6-cyclohexyl-sym-triazine, 2,4-diamino-6-chloro-sym-triazine, 2,4-diamino-6-mercapto-sym-triazine, ameline (N, N, N ', N'- Tetracyanoethylbenzoguanamine).

Specific examples of the adduct of an amino-substituted triazine compound and formaldehyde include N-methylol melamine, N, N′-dimethylol melamine, and N, N ′, N ″ -trimethylol melamine.
Specific examples of condensates of amino-substituted triazine compounds and formaldehyde include melamine / formaldehyde condensates.

  Examples of the urea derivative include N-substituted urea, urea condensate, ethylene urea, hydantoin compound, and ureido compound. Specific examples of the N-substituted urea include methylurea, alkylenebisurea and aryl-substituted urea substituted with a substituent such as an alkyl group. Specific examples of the urea condensate include urea and formaldehyde condensates.

Specific examples of the hydantoin compound include hydantoin, 5,5-dimethylhydantoin, 5,5-diphenylhydantoin and the like.
Specific examples of the ureido compound include allantoin.
Specific examples of the imide compound include succinimide, glutarimide, and phthalimide.

Examples of the hydrazine derivative include hydrazide compounds. In the present invention, it is preferable to use a dihydrazide compound as the stabilizer (H) containing formaldehyde-reactive nitrogen.
In particular, as the dihydrazide compound, it is preferable to use a dihydrazide compound selected from the group consisting of an aromatic dihydrazide compound and an aliphatic dihydrazide compound having a solubility in 100 g of water at 20 ° C. of less than 1 g.
An aromatic dihydrazide compound is a compound in which hydrazine reacts with each acid group of an aromatic compound having two carboxylic acid groups or sulfonic acid groups. For example, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 1,5-naphthalene. Dicarbohydrazide, 1,8-naphthalenedicarbohydrazide, 2,6-naphthalenedicarbohydrazide, 1,5-diphenylcarbonohydrazide, 2,4-toluenedisulfonyl hydrazide, 4,4′-oxybisbenzenesulfonyl hydrazide Etc.

  Examples of the aliphatic dihydrazide compound having a solubility in 100 g of water at 20 ° C. (hereinafter sometimes referred to as water solubility) of less than 1 g include oxalic acid dihydrazide (water solubility of 0.2 g or less), sebacic acid dihydrazide (same as above). 0.01 g or less), 1,12-dodecanedicarbohydrazide (0.01 g or less), 1,18-octadecanedicarbohydrazide (0.1 g or less), and the like. An aliphatic dihydrazide compound having a water solubility of 1 g or more tends to have an insufficient effect of suppressing formaldehyde generation from the polyacetal resin composition.

  Preferable examples of the dihydrazide compound include 2,6-naphthalenedicarbohydrazide, terephthalic acid dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, 1,12-dodecanedicarbohydrazide and the like. In particular, it is preferable to use sebacic acid dihydrazide, 1,12-dodecanedicarbohydrazide, terephthalic acid dihydrazide, or the like.

  As the stabilizer (H) containing formaldehyde-reactive nitrogen, amide compounds can be used as described above. In addition, acrylamide and derivatives thereof, and copolymers of acrylamide and derivatives thereof with other vinyl monomers are also available. Examples thereof include a poly-β-alanine copolymer obtained by polymerizing acrylamide and its derivatives and other vinyl monomers in the presence of a metal alcoholate.

  The content of the stabilizer (H) containing formaldehyde-reactive nitrogen is preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the polyacetal resin (E). If the content is less than 0.01 parts by mass, the effect of reducing the generation of formaldehyde from the molded product is insufficient. Conversely, if the content exceeds 1 part by mass, the amount of mold deposits at the time of injection molding increases, and the molding is efficient. It is easy to be unable to do. The more preferable content of the dihydrazide compound is 0.03 to 0.3 part by mass, and more preferably 0.05 to 0.15 part by mass.

[11. Colorant (I)]
When the molded product of the polyacetal resin composition of the present invention is diluted with the polyacetal resin (E) and used, a colorant (I) selected from inorganic and organic pigments may be blended.
As the inorganic and organic pigments constituting the colorant (I), general inorganic pigments and organic pigments described in “Handbook of Pigments (edited by the Japan Pigment Technical Association)” can be used. Examples of the inorganic pigments include (complex) metal oxides containing titanium such as titanium oxide and titanium yellow, zinc oxide, iron oxide, carbon black, ultramarine blue, zinc sulfide, and antimony trioxide. Examples of the organic pigment include phthalocyanine, anthraquinone, quinacridone, azo, isoindolinone, quinophthalone, perinone, and perylene pigments.

The content of the colorant (I) is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the polyacetal (E) resin. If the content is less than 0.01 parts by mass, it cannot be colored significantly. The content of the colorant is more preferably 0.05 parts by mass or more, and still more preferably 0.1 parts by mass or more. The upper limit of the content is more preferably 3 parts by mass or less, and still more preferably 2 parts by mass or less. By setting the colorant to 5 parts by mass or less, generation of formaldehyde tends to be suppressed.
When blending the colorant (I), a dispersion aid or a spreading agent may be blended. Examples of the dispersion aid include amide wax, ester wax, and olefin wax, and examples of the spreading agent include liquid paraffin. A pigment may be used in combination with a dye to achieve a desired color.

[12. Other ingredients]
When the molded product of the polyacetal resin composition of the present invention is diluted with the polyacetal resin (E) and used, an alkali metal or alkaline earth metal hydroxide, inorganic acid salt, alkoxide, or the like may be further blended. For example, hydroxides such as sodium, potassium, calcium and magnesium, inorganic acid salts such as carbonate, phosphate, silicate and borate, and alkoxides such as methoxide and ethoxide are blended. In particular, an alkaline earth metal compound is preferably blended, and calcium hydroxide, magnesium hydroxide, calcium carbonate, or magnesium carbonate is particularly blended. When mix | blending an alkaline-earth metal compound, Preferably it is 1 mass part or less with respect to 100 mass parts of polyacetal resin (E), More preferably, it is made to contain in the ratio of 0.5 mass part or less.

When the molded product of the polyacetal resin composition of the present invention is used after being diluted with the polyacetal resin (E), in addition to the above components, various known additives within a range not impairing the object of the present invention Or a filler may be blended.
Examples of the additives include antioxidants, lubricants, nucleating agents, mold release agents, plasticizers, antistatic agents, flame retardants, and the like, and fillers include glass fibers, glass flakes, glass beads, talc, Examples include mica and potassium titanate whiskers.

  When the molded product of the polyacetal resin composition of the present invention is diluted with the polyacetal resin (E) and used for molding, the molded product of the polyacetal resin composition of the present invention used as the above-described polyacetal resin (E) or matting agent. And after weighing a predetermined amount of each component such as an ultraviolet absorber, a hindered amine light stabilizer and the like blended as necessary, dry blending with a mixer such as a tumbler mixer, it may be used as it is, The dry blend may be melt-kneaded to form resin composition pellets and then subjected to molding. The melt-kneading can use the same technique as the melt-kneading method of the molded article of the polyacetal resin composition of the present invention described above.

[13. Manufacturing of molded products]
The above-mentioned molded product of the polyacetal resin composition of the present invention and the polyacetal resin composition obtained by diluting the polyacetal resin composition of the present invention can be molded according to a known polyacetal resin molding process. In order to mold a molded product, injection molding is particularly preferable from the viewpoints of fluidity and workability.
Examples of the molded article comprising the polyacetal resin composition of the present invention include products such as raw materials such as pellets, round bars, and thick plates, sheets, tubes, various containers, machines, electricity, automobiles, building materials, and other various parts. It is particularly suitable for automotive interior parts such as seat belt guides, automotive parts such as switches, shift lever related parts, and gear change hooks.

  Hereinafter, the present invention will be described more specifically with reference to examples. The materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

The raw materials used in Examples and Comparative Examples are shown below.
(A) Polyacetal resin:
A hindered phenolic compound (trade name “Irganox 245 manufactured by Ciba Specialty Chemicals Co., Ltd.”) was used for an acetal copolymer produced by using 1,3-dioxolane as a comonomer so as to be 4.2% by mass with respect to the resin. ], Polyacetal stabilized by adding 0.3% by mass of ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate]) and 0.1% by mass of melamine Resin, melt index (ASTM-D1238 standard: 190 ° C., 2.16 kg) 16 g / 10 min

(B) Thermoplastic polyurethane:
(B-1) Aliphatic polyurethane Thermoplastic polyurethane obtained by reacting adipic acid, 1,4-butanediol and 1,6-hexamethylene diisocyanate (B-2) Alicyclic polyurethane Adipic acid, 1,4 -Thermoplastic polyurethane obtained by reacting butanediol and 4,4'-methylene-bis- (cyclohexyl isocyanate) (B-3) Aromatic polyurethane Adipic acid, 1,4-butanediol and 4,4'- Thermoplastic polyurethane obtained by reacting diphenylmethane diisocyanate

(C) Isocyanate compound:
(C-1) 4,4′-methylene-bis- (cyclohexyl isocyanate)
(C-2) 1,6-hexamethylene diisocyanate
(C-3) 4,4′-diphenylmethane diisocyanate

(D) Polyhydric alcohol having 3 or more hydroxyl groups in the molecule:
Pentaerythritol

(E) Polyacetal resin:
A hindered phenolic compound (trade name “Irganox 1098, manufactured by Ciba Specialty Chemicals Co., Ltd.”) was used for an acetal copolymer produced by using 1,3-dioxolane as a comonomer so as to be 4.2% by mass with respect to the resin. ”, 0.03% by mass of N, N′-hexane-1,6-diylbis [3- (3,5-di-tert-butyl-4-hydroxyphenylpropionamide) and 0.1% by mass of melamine Stabilized polyacetal resin, melt index (ASTM-D1238 standard: 190 ° C., 2.16 kg) 9.0 g / 10 min

(F) UV absorber:
2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (vapor pressure at 20 ° C. 2.0 × 10 ⁻¹⁰ Pa), Ciba Specialty Chemicals Product name “Chinubin 234”

(G) Hindered amine light stabilizer:
Bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, manufactured by Sankyo Lifetech Co., Ltd., trade name “Sanol LS-765”

Example 1
20 parts by mass of the aliphatic thermoplastic polyurethane (B-1), 1.0 part by mass of 4,4′-methylene-bis- (cyclohexyl isocyanate) (C-1) with respect to 100 parts by mass of the polyacetal resin (A). Then, 0.4 parts by mass of pentaerythritol (D) was weighed and uniformly mixed using a super mixer manufactured by Kawada Seisakusho, followed by a twin screw extruder (“PCM-30” manufactured by Ikekai Tekko Co., Ltd., screw diameter). 30 mm) was melt kneaded under the conditions of a screw rotation speed of 120 rpm and a cylinder set temperature of 190 ° C., and then extruded into a strand shape and pelletized with a pelletizer.
Subsequently, immediately after molding, the obtained pellets were heat-treated for 16 hours in a stationary shelf dryer at a temperature of 90 ° C. to obtain polyacetal resin composition pellets. After standing at room temperature and normal pressure for 24 hours, pre-drying is performed for 4 hours in a stationary shelf dryer at a temperature of 80 ° C. for 4 hours, and a test piece is molded by the following method, followed by the evaluation method described below. The results shown in Table 1 were obtained.

[Preparation of flat specimen]
A 100 mm × 40 mm × 2 mm plate was molded at a cylinder temperature of 195 ° C. and a mold temperature of 80 ° C. using an injection molding machine “PS-40” manufactured by Nissei Plastic Industries.

[Measurement and evaluation method]
Measurement and evaluation were performed by the following methods.
(A) Glossiness:
Using the flat plate test piece, measurement was performed at a reflection angle of 60 degrees with a gloss meter (Gloss Meter VG2000) manufactured by Nippon Denshoku Industries Co., Ltd.

(B) Matte evaluation:
The light from the fluorescent lamp was reflected on the flat test piece, and the blur condition of the light source at that time was visually confirmed, and the determination was made in the following four stages.
・ Reflection is so blurred that the light source does not retain its original shape.
・ Light source is blurred and reflected → ○
-The light source outline is slightly blurred and reflected.
・ Light source is clearly reflected → ×

(C) Weather resistance test Using the flat plate test piece, Suga Test Instruments Co., Ltd. Sunshine Weather Meter S80, 83 ° C. (black panel temperature), no rain, light filter: test condition of # 255, 60 hours Every time, the surface of the test piece was observed with a 40 times microscope, and the presence or absence of a crack was confirmed. The time until cracks began to be observed on the surface of the molded product was defined as the crack generation time, which was used as an indicator of weather resistance. The longer the crack occurrence time, the better the weather resistance.
Moreover, about the test piece, the color difference ((DELTA) E) of the test piece before a test and 60 hours after was measured with the following method.
Using a spectrocolorimetric color difference meter (Nippon Denshoku Industries Co., Ltd., SE2000), the color difference (ΔE) before the weather resistance test and after the 60 hour light resistance test was evaluated by the following equation.
ΔE = ((ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ) ^1/2
It can be said that the smaller the ΔE, the smaller the color change and the better the weather resistance.

(Examples 2 to 8)
In Example 1, the components used and the blending amounts thereof were as shown in Table 1, and all the treatments were carried out in the same manner as in Example 1 except that the heat treatment conditions were as shown in Table 1. Polyacetal resin composition pellets Got. In addition, preliminary drying before injection molding (drying for 4 hours using a stationary shelf dryer at a temperature of 80 ° C.) was also performed in the same manner. Moreover, the conditions of the heat processing 1-3 in a table | surface are as follows.
Heat treatment 1: Immediately after pellet forming, heat treatment for 16 hours with a stationary shelf dryer at 90 ° C. Heat treatment 2: After pellet formation, the plate is allowed to stand at room temperature and normal pressure for 25 hours, and then a stationary shelf dryer at 90 ° C. 16 hours heat treatment Heat treatment 3: After pellet forming, just left at room temperature and normal pressure for 25 hours, no heat treatment results are shown in Table 1.

(Comparative Examples 1-8)
In Example 1, the components used and their blending amounts were as shown in Table 2, and all the treatments were carried out in the same manner as in Example 1 except that the heat treatment conditions were as shown in Table 2. Polyacetal resin composition pellets Got. The preliminary drying before injection molding was performed in the same manner. The results are shown in Table 2.

Example 9
12.5 parts by mass of the polyacetal resin composition obtained in Example 1, 0.35 parts by mass of the ultraviolet absorber (F), hindered amine light stabilizer (G) 0. 100 parts by mass of the polyacetal resin (E). 35 parts by weight were weighed and mixed uniformly using a super mixer manufactured by Kawada Manufacturing Co., Ltd., and then rotated using a twin-screw extruder ("PCM-30" manufactured by Ikekai Tekko Co., Ltd., screw diameter 30 mm) according to a conventional method. After melting under the conditions of several 120 rpm and a cylinder set temperature of 190 ° C., it was extruded into a strand shape and pelletized with a pelletizer to obtain polyacetal resin composition pellets. The obtained pellets were allowed to stand at room temperature and normal pressure for 24 hours, then dried in a stationary shelf dryer at a temperature of 80 ° C. for 4 hours, and then a test piece was molded in the same manner as in Example 1. By performing the evaluation method similar to 1, the results shown in Table 3 were obtained.

(Examples 10 to 12)
In Example 9, all the treatments were carried out in the same manner as in Example 9 except that the components used and the blending amounts thereof were as shown in Table 3, and the results shown in Table 3 were obtained. The preliminary drying before injection molding was performed in the same manner.

(Comparative Example 9)
25 parts by mass of the polyacetal resin composition obtained in Comparative Example 2, 0.35 parts by mass of the ultraviolet absorber (F), 0.35 parts by mass of the hindered amine light stabilizer (G) with respect to 100 parts by mass of the polyacetal resin (E). The parts were weighed, and all subsequent processing was performed in the same manner as in Example 9, and the results shown in Table 3 were obtained. The preliminary drying before injection molding was performed in the same manner.

As is clear from Tables 1 and 2, the molded product of the polyacetal resin composition of the present invention has excellent matting properties and weather resistance (Examples 1 to 8).
On the other hand, when an aromatic thermoplastic polyurethane is used as the thermoplastic polyurethane (B) or when an aromatic isocyanate compound is used as the isocyanate compound (C), the weather resistance is poor (Comparative Examples 2 to 6).
Moreover, after heat treatment is not performed within 24 hours after obtaining the resin composition pellets, the matte properties are inferior (Comparative Examples 7 and 8).

  As is apparent from Table 3, when the molded product of the polyacetal resin composition of the present invention (pellet of Example 1) is blended with the polyacetal resin as a matting agent, it has excellent matting properties and weather resistance. (Examples 9 to 12). On the other hand, when a molded product of a polyacetal resin composition using an aromatic thermoplastic polyurethane and an aromatic isocyanate compound (pellet of Comparative Example 2) is blended with a polyacetal resin as a matting agent, the weather resistance is greatly inferior and matte. Also slightly inferior (Comparative Example 9).

  The polyacetal resin composition of the present invention thus obtained has a high matte property and excellent weather resistance, so as a polyacetal resin material, various molded parts, particularly automobile interior parts, houses, etc. It can be suitably used for interior parts and the like, and has very high industrial applicability.

Claims (6)

  1 to 120 parts by weight of an aliphatic or alicyclic thermoplastic polyurethane (B), 0.01 to 10 parts by weight of an aliphatic or alicyclic isocyanate compound (C) and 100 parts by weight per 100 parts by weight of the polyacetal resin (A) Next, 0.01 to 5 parts by mass of a polyhydric alcohol (D) having 3 or more hydroxyl groups was melt-kneaded to obtain a molded product of the resin composition, and then the molded product was subjected to heat treatment within 24 hours for crosslinking. A polyacetal resin composition obtained by promoting the reaction.   The polyacetal resin composition according to claim 1, wherein the heat treatment is performed by holding at a temperature of 50 to 130 ° C. for 1 hour or more.   A polyacetal resin composition comprising the polyacetal resin composition according to claim 1 or 2 in an amount of 1 to 120 parts by mass with respect to 100 parts by mass of the polyacetal resin (E).   Furthermore, 0.01-5 mass parts of ultraviolet absorbers (F) are contained with respect to 100 mass parts of polyacetal resin (E), The polyacetal resin composition of Claim 3 characterized by the above-mentioned.   Furthermore, 0.01-5 mass parts of hindered amine light stabilizers (G) are contained with respect to 100 mass parts of polyacetal resin (E), The polyacetal resin composition of Claim 3 or 4 characterized by the above-mentioned.   The molded article formed by shape | molding the polyacetal resin composition of any one of Claims 1-5.