JP2019026811A - Polyoxymethylene resin composition - Google Patents

Abstract

To provide a polyoxymethylene resin composition that is excellent in impact resistance, rigidity, and slidability, and also excellent in impact strength at low temperature and dart impact strength.SOLUTION: A polyoxymethylene resin composition has (A) polyoxymethylene resin 100 pts.mass and (B) modifier 0.5-50 pts.mass, and the (B) modifier has (b-1) thermoplastic polyurethane and (b-2) graft rubber copolymer. The (b-2) graft rubber copolymer has a structure consisting of two or more layers. In the total of the (b-1) thermoplastic polyurethane and the (b-2) graft rubber copolymer, the content of the (b-1) thermoplastic polyurethane is 17-95 mass%.SELECTED DRAWING: None

Description

  The present invention relates to a polyoxymethylene resin composition.

  Polyoxymethylene resin has an excellent balance of mechanical strength, chemical resistance, slidability, and wear resistance, and can be easily processed. Therefore, polyoxymethylene resins are widely used as mechanical engineering parts, automobile parts, and other parts of electrical equipment as one of typical engineering plastics.

  Also, for polyoxymethylene resins, there are market demands for improved impact strength in many potential applications. Various techniques for improving impact strength by blending specific components into a resin such as polyoxymethylene resin have been disclosed.

  As a technique for improving the impact strength, Patent Document 1 discloses a resin-made hollow molded product in which a core-shell polymer and / or a thermoplastic polyurethane resin are blended with a polyoxymethylene resin. Patent Document 2 discloses a composition containing a brittle plastic such as polystyrene and a rubber mixture. Patent Document 3 discloses a composition comprising a polyoxymethylene resin, a rubber elastic graft polymer based on poly (meth) acrylic acid ester or silicone rubber, and a polymer. Patent Document 4 discloses a composition containing a polyoxymethylene resin and a thermoplastic polyurethane resin and / or a core-shell polymer impact modifier.

Japanese Patent Laid-Open No. 7-195596 Japanese Patent No. 3929896 JP-A-6-57097 Japanese Unexamined Patent Publication No. 7-126483

However, the technique described in Patent Document 1 focuses on blow molding. Patent Document 1 discloses an example of a composition in which a thermoplastic polyurethane resin and a core-shell polymer are used in combination. However, such a composition has a material rigidity point, a low temperature impact strength point, a dirt point, and the like. There was room for improvement in terms of impact strength.
Patent Document 2 does not disclose a polyoxymethylene resin composition, and the composition described in Patent Document 2 is improved at least in terms of impact strength at low temperatures and in terms of dart impact strength. Had room for.
Moreover, the composition described in Patent Document 3 has room for improvement in terms of both impact resistance and rigidity, sliding characteristics, impact strength at low temperatures, dirt impact strength, and the like.
The technique described in Patent Document 4 also has room for improvement in terms of slidability and material rigidity.

  Thus, in the above-described conventional technology, there is room for improvement in terms of impact resistance, rigidity, slidability, low temperature impact strength and dirt impact strength related to polyoxymethylene resin, and further improvement is desired. .

  Therefore, an object of the present invention is to provide a polyoxymethylene resin composition which is excellent in impact resistance, rigidity and slidability, and excellent in low temperature impact strength and dirt impact strength. Another object of the present invention is to provide a molded article that is excellent in impact resistance, rigidity, and slidability and that is excellent in low-temperature impact strength and dart impact strength.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above-mentioned problems can be solved by including a modifier composed of a plurality of components at a specific ratio in the polyoxymethylene resin, and the present invention has been completed. It came to do.

That is, the present invention is as follows.
[1]
(A) containing 100 parts by mass of a polyoxymethylene resin and (B) 0.5 to 50 parts by mass of a modifier,
The (B) modifier includes (b-1) a thermoplastic polyurethane and (b-2) a graft rubber copolymer,
The (b-2) graft rubber copolymer has a structure of two or more layers,
The ratio of the (b-1) thermoplastic polyurethane in the total of the (b-1) thermoplastic polyurethane and the (b-2) graft rubber copolymer is 17 to 95% by mass.
The polyoxymethylene resin composition characterized by the above-mentioned.
[2]
The polyoxymethylene resin composition according to item [1], wherein (b-1) the thermoplastic polyurethane is an ester polyurethane.
[3]
In the item [2], the ester polyurethane has an ester component ratio (molar ratio) of 4 to 5 and a polyol component ratio (molar ratio) of 5 to 6 when the isocyanate component is 1. The polyoxymethylene resin composition described.
[4]
The polyoxymethylene resin composition according to item [2] or [3], wherein the ester-based polyurethane contains two types of polyol components.
[5]
The polyoxymethylene according to any one of items [1] to [4], wherein the (b-2) graft rubber copolymer has an amount of Si element of 1 to 25% by mass in ICP-MS analysis. Resin composition.
[6]
Items (1) to (5), wherein the (b-2) graft rubber copolymer contains a silicone / acrylic polymer and the amount of Si element in ICP-MS analysis is 2 to 10% by mass. The polyoxymethylene resin composition according to any one of the above.
[7]
The polyoxymethylene resin composition according to any one of items [1] to [6], wherein the concentration of sulfate ions is 0.01 to 0.2 ppm.
[8]
The polyoxymethylene resin according to any one of items [1] to [7], wherein the (A) polyoxymethylene resin has a melt flow rate of 0.1 to 60 g / 10 min.
[9]
The polyoxymethylene resin composition according to any one of items [1] to [8], which has a pellet shape.
[10]
A molded article comprising the polyoxymethylene resin composition according to any one of items [1] to [9].

  According to the present invention, it is possible to provide a polyoxymethylene resin composition that is excellent in impact resistance, rigidity, and slidability and excellent in low-temperature impact strength and dirt impact strength. Further, according to the present invention, it is possible to provide a molded article that is excellent in impact resistance, rigidity, and slidability, and that is excellent in low-temperature impact strength and dart impact strength.

  Hereinafter, although the form for implementing this invention (henceforth "this embodiment") is demonstrated in detail, this invention is not limited to the following description, In the range of the summary Various modifications can be made.

(Polyoxymethylene resin composition)
The polyoxymethylene resin composition of the present embodiment contains (A) 100 parts by mass of a polyoxymethylene resin and (B) 0.5 to 50 parts by mass of a modifier, and the (B) modifier is And (b-1) a thermoplastic polyurethane and (b-2) a graft rubber copolymer, wherein the (b-2) graft rubber copolymer has a structure of two or more layers. . Moreover, the polyoxymethylene resin composition of this embodiment may contain (C) a coloring agent and another additive as an arbitrary component.

Furthermore, in the polyoxymethylene resin composition of the present embodiment, the ratio of (b-1) thermoplastic polyurethane in the total of (b-1) thermoplastic polyurethane and (b-2) graft rubber copolymer is 17 to 95. It is characterized by being mass%. When the ratio is 17% by mass or more, impact strength at low temperatures and dart impact strength can be improved, and when it is 95% by mass or less, slidability can be improved. When importance is attached to the improvement of the dart impact strength, the ratio is preferably 40% by mass or more, more preferably 50% by mass or more, further preferably 60% by mass or more, and 70% by mass. % Or more, more preferably 90% by mass or less, more preferably 85% by mass or less, further preferably 84% by mass or less, and 80% by mass or less. Is more preferable. Further, when importance is attached to improvement in slidability, the ratio is preferably 18% by mass or more, more preferably 19% by mass or more, further preferably 20% by mass or more, It is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less.
Hereinafter, each component which comprises the polyoxymethylene resin composition of this embodiment is explained in full detail.

<(A) Polyoxymethylene resin>
(A) polyoxymethylene resin contained in the polyoxymethylene resin composition of the present embodiment (in this specification, it may be described as (A) component or (A). Hereinafter, component (B), The same applies to the component (b-1), the component (b-2), and the component (C).

  Examples of the (A) polyoxymethylene resin that can be used in the present embodiment include polyoxymethylene homopolymers and polyoxymethylene copolymers.

Specifically, the polyoxymethylene homopolymer is substantially obtained by homopolymerizing a formaldehyde monomer or a cyclic oligomer of formaldehyde such as a trimer of formaldehyde (trioxane) or a tetramer (tetraoxane). Examples include polyoxymethylene homopolymers composed only of oxymethylene units.
Specifically, polyoxymethylene copolymers include formaldehyde monomers, cyclic oligomers of formaldehyde such as formaldehyde trimers (trioxanes) or tetramers (tetraoxanes), and cyclic ethers or cyclics as comonomers. Examples include polyoxymethylene copolymers obtained by copolymerizing with formal. Here, as cyclic ether or cyclic formal, ethylene oxide; propylene oxide; epichlorohydrin; 1,3-dioxolane; glycol such as 1,4-butanediol formal; or cyclic formal of diglycol;

  When a trioxyoxane is used to obtain a polyoxymethylene copolymer, the amount of comonomer such as 1,3-dioxolane is generally 0.1 to 60 mol, preferably 0.1 to 20 mol, relative to 100 mol of trioxane. More preferred is 0.13 to 10 mol. In this embodiment, the melting point of the polyoxymethylene copolymer is preferably 162 ° C to 173 ° C, more preferably 167 ° C to 173 ° C, and further preferably 167 ° C to 171 ° C. A polyoxymethylene copolymer having a melting point of 162 ° C. to 173 ° C. can be obtained by using about 1.3 to 3.5 mol of a comonomer with respect to 100 mol of trioxane. The melting point can be measured by DSC.

  The polyoxymethylene copolymer includes a branched polyoxymethylene copolymer obtained by copolymerizing a monomer of formaldehyde and / or a cyclic oligomer of formaldehyde and a monofunctional glycidyl ether, and a single amount of formaldehyde. Examples thereof also include polyoxymethylene copolymers having a crosslinked structure obtained by copolymerization of a cyclic oligomer of a form and / or formaldehyde and a polyfunctional glycidyl ether.

  Furthermore, (A) polyoxymethylene resin may contain the block copolymer which has a different block part different from the repeating structural unit of polyoxymethylene.

  (A) When the polyoxymethylene resin contains a block copolymer, the different block portion contains the polyoxymethylene resin composition of this embodiment, and (B) the modifying agent is present selectively and stably. Can be made. Thereby, it becomes possible to express much more stable wear resistance.

  As the block copolymer here, a polyoxymethylene homopolymer having at least one block part represented by any one of the following general formulas (1) to (4), or a polyoxymethylene copolymer (both of them are referred to as “ Also referred to as "block copolymer").

In the general formulas (1), (2), and (3), R ₁ and R ₂ are each independently selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group. When one kind of chemical species is shown and R ₁ and R ₂ are plural, they may be the same or different.

In the above general formulas (1), (2), and (4), R ₃ , R 5, R ₆ are one chemistry selected from the group consisting of alkyl groups, substituted alkyl groups, aryl groups, and substituted aryl groups. Indicates the species.

In the general formula (4), R ₄ represents one chemical species selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, and a substituted aryl group, and when R ₄ is plural, Each may be the same or different.

  In the general formulas (1), (2), and (3), m represents an integer of 2 to 6, and an integer of 2 to 4 is preferable.

  In the general formulas (1), (2), and (3), n represents an integer of 1 to 1000, and an integer of 10 to 250 is preferable.

  In the general formula (4), p represents an integer of 2 to 6, and two p may be the same or different.

In the general formula (4), q and r each represent a positive number, q is 2 to 100 mol%, r is 0 to 98 mol% with respect to a total of 100 mol% of q and r, − The (CH (CH ₂ CH ₃ ) CH ₂ ) — unit and the — (CH ₂ CH ₂ CH ₂ CH ₂ ) — unit exist in random or block form, respectively.

  The group represented by the general formula (1) is a residue obtained by eliminating a hydrogen atom from the (poly) alkylene oxide adduct of alcohol, and the group represented by the general formula (2) is a carboxylic acid. It is a residue obtained by eliminating a hydrogen atom from a (poly) alkylene oxide adduct, and the group represented by the general formula (3) is a residue obtained by eliminating a hydrogen atom from (poly) alkylene oxide.

  Examples of the block copolymer having a block portion include, for example, JP-A-57-31918, JP-A-60-170652, JP-A-2002-3696, JP-A-2002-234922, and JP-A-2002-3694. It can be prepared with reference to the method described in the Gazette.

  The block part of the block copolymer represented by the formulas (1) to (4) is a terminal part of a compound constituting a block having a functional group such as a hydroxyl group at both terminals or one terminal in the polymerization process of the polyoxymethylene resin. It is obtained by reacting with

  The amount of the block portion represented by the above formulas (1) to (4) in the block copolymer is not particularly limited, but the ratio of the block portion when the block copolymer is 100% by mass is 0.001. It is preferable that it is mass%-30 mass%. When the above ratio is 0.001% by mass or more, the slidability can be maintained stably, and when it is 30% by mass or less, the polyoxymethylene resin composition of the present embodiment. It is possible to suppress a decrease in the rigidity of the molded body made of. From the same viewpoint, the above ratio is more preferably 0.01% by mass or more, further preferably 0.1% by mass or more, further preferably 1% by mass or more, and 15% It is more preferably at most 8% by mass, even more preferably at most 8% by mass.

  Further, the molecular weight of the block portion in the block copolymer is preferably 10,000 or less, more preferably 8000 or less, from the viewpoint of not reducing the rigidity of the molded article containing the polyoxymethylene resin composition of the present embodiment. More preferably, it is 5000 or less. On the other hand, the lower limit of the molecular weight of the block portion in the block copolymer is not particularly limited, but is preferably 100 or more from the viewpoint of maintaining stable slidability.

Examples of the compound forming the block portion in the block copolymer is not particularly limited, for _{example, C 18 H 37 O (CH} 2 CH 2 O) 40 C 18 H 37, C 11 H 23 CO 2 (CH 2 CH 2 O ) ₃₀ H, C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₇₀ H, C ₁₈ H ₃₇ O (CH ₂ CH ₂ O) ₄₀ H, polyethylene glycol having both hydroxyl groups, both hydroxyl groups Polypropylene glycol, hydrogenated polybutadiene having hydroxyl groups at both ends, hydroxyalkylated polyethylene glycol at both ends, hydroxyalkylated polypropylene glycol at both ends, hydroxyalkylated hydrogenated polybutadiene at both ends, glycidyl compounds (monofunctional and polyfunctional) Etc.

  Although it does not specifically limit as a polymerization catalyst used for superposition | polymerization of a polyoxymethylene copolymer, For example, cationically active catalysts, such as a Lewis' acid, a proton acid, its ester, or an anhydride, are preferable. The Lewis acid is not particularly limited, and examples thereof include boric acid, tin, titanium, phosphorus, arsenic and antimony halides. More specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, Examples thereof include phosphorus pentafluoride, phosphorus pentachloride, antimony pentafluoride, and complex compounds or salts thereof. In addition, the protonic acid and its ester or anhydride are not particularly limited, and examples thereof include perchloric acid, trifluoromethanesulfonic acid, perchloric acid-tertiary butyl ester, acetyl perchlorate, and trimethyloxonium hexafluorophosphate. . Among these, as the polymerization catalyst, boron trifluoride, boron trifluoride hydrate, and a coordination complex compound of boron trifluoride with an organic compound containing an oxygen atom or a sulfur atom are more preferable. Suitable examples include boron trifluoride diethyl ether and boron trifluoride di-n-butyl ether.

The production method of the polyoxymethylene copolymer is not particularly limited, and a conventionally known method can be used. For example, U.S. Pat. Nos. 3,027,352, 3,803,094 and 1,116,421 are disclosed. No. 1495228, No. 1720358, No. 3018898, JP-A-58-98322 and JP-A-7-70267. In addition, since the polyoxymethylene copolymer obtained by the above method has a thermally unstable terminal portion [-(OCH ₂ ) _n —OH group], the unstable terminal portion is decomposed and removed. It is preferable.

  Specifically, in the process of decomposing and removing the unstable terminal portion, in the presence of at least one quaternary ammonium compound represented by the following formula (5), a temperature not lower than the melting point of the polyoxymethylene copolymer and not higher than 260 ° C. Then, heat treatment is performed in a state where the polyoxymethylene copolymer is melted.

Here, in formula (5), R ^a , R ^b , R ^c and R ^d are each independently a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; An aralkyl group in which at least one hydrogen atom in a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms is substituted with an aryl group having 6 to 20 carbon atoms; or at least one in an aryl group having 6 to 20 carbon atoms Represents an alkylaryl group in which a hydrogen atom is substituted with a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, and the substituted or unsubstituted alkyl group is linear, branched, or cyclic. The substituent in the substituted alkyl group is a halogen atom, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, or an amide group. In the unsubstituted alkyl group, aryl group, aralkyl group, and alkylaryl group, a hydrogen atom may be substituted with a halogen atom. n ′ represents an integer of 1 to 3. X represents a hydroxyl group or an acid residue of a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid other than a hydrogen halide, an oxo acid, an inorganic thioacid, or an organic thioacid having 1 to 20 carbon atoms.

The quaternary ammonium compound is not particularly limited as long as it is represented by the above formula (5), but R ^a and R in the formula (5) from the viewpoint of more effectively and surely achieving the above effect according to the present embodiment. ^b , R ^c and R ^d are each independently preferably an alkyl group having 1 to 5 carbon atoms or a hydroxyalkyl group having 2 to 4 carbon atoms, and further R ^a , R ^b , R ^c and R It is particularly preferred that at least one of ^d is a hydroxyethyl group. Although it does not specifically limit as such a quaternary ammonium compound, Specifically, tetramethylammonium, tetoethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1 , 6-hexamethylenebis (trimethylammonium), decamethylene-bis- (trimethylammonium), trimethyl-3-chloro-2-hydroxypropylammonium, trimethyl (2-hydroxyethyl) ammonium, triethyl (2-hydroxyethyl) ammonium, Tripropyl (2-hydroxyethyl) ammonium, tri-n-butyl (2-hydroxyethyl) ammonium, trimethylbenzylammonium, triethylbenzyla Monium, tripropylbenzylammonium, tri-n-butylbenzylammonium, trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, monomethyltrihydroxyethylammonium, monoethyltrihydroxyethylammonium, okdadecyltri (2- Hydroxyethyl) ammonium, tetrakis (hydroxyethyl) ammonium hydroxide, etc .; quaternary ammonium compounds such as hydrochloric acid, odorous acid, hydrofluoric acid, etc .; quaternary ammonium compounds such as sulfuric acid, nitric acid, Oxo acid salts such as phosphoric acid, carbonic acid, boric acid, chloric acid, iodic acid, silicic acid, perchloric acid, chlorous acid, hypochlorous acid, chlorosulfuric acid, amidosulfuric acid, disulfuric acid, tripolyphosphoric acid; the above quaternary Of ammonium compounds Thioacid salts such as sulfuric acid; carboxylates such as formic acid, acetic acid, propionic acid, butanoic acid, isobutyric acid, pentanoic acid, caproic acid, caprylic acid, capric acid, benzoic acid, oxalic acid, etc. of the above quaternary ammonium compounds ; Among these, hydroxides (OH ⁻ ), sulfuric acid (HSO ⁴⁻ , SO ₄ ²⁻ ), carbonic acid (HCO ³⁻ , CO ³²⁻ ), boric acid (B (OH)) of the above quaternary ammonium compounds. ^4- ) and carboxylic acid salts are preferred. Of the carboxylic acids, formic acid, acetic acid, and propionic acid are particularly preferred. A quaternary ammonium compound may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, you may use together amines, such as ammonia and a triethylamine which are well-known decomposition | disassembly promoters of an unstable terminal part with the said quaternary ammonium compound.

The amount of the quaternary ammonium compound used is 0 in terms of the amount of nitrogen derived from the quaternary ammonium compound represented by the following formula (6) with respect to the total mass of the polyoxymethylene copolymer and the quaternary ammonium compound. 0.05 to 50 ppm by mass is preferable, and 1 to 30 ppm by mass is more preferable.
Amount of quaternary ammonium compound used = P × 14 / Q (6)

  Here, in Formula (6), P shows the density | concentration (mass ppm) with respect to the polyoxymethylene copolymer of a quaternary ammonium compound, 14 is the atomic weight of nitrogen, Q shows the molecular weight of a quaternary ammonium compound.

  When the amount of the quaternary ammonium compound used is 0.05 mass ppm or more, the decomposition and removal rate of the unstable terminal portion tends to be further improved. Moreover, it exists in the tendency for the color tone of the polyoxymethylene copolymer after decomposition | disassembly removal of an unstable terminal part to be more excellent because it is 50 mass ppm or less.

  The unstable terminal portion of the polyoxymethylene resin in the present embodiment can be decomposed and removed by heat treatment in a state where the polyoxymethylene copolymer is melted at a temperature of the melting point or higher and 260 ° C. or lower. An apparatus used for the decomposition and removal treatment is not particularly limited, but an extruder, a kneader, and the like are preferable. Formaldehyde generated by decomposition is usually removed under reduced pressure. The method of mixing the quaternary ammonium compound and the polyoxymethylene copolymer is not particularly limited. For example, a method of adding the quaternary ammonium compound as an aqueous solution in the step of deactivating the polymerization catalyst, or a polymer produced by polymerization. The method of spraying a quaternary ammonium compound to oxymethylene copolymer powder is mentioned. Whichever method is used, the quaternary ammonium compound may be present in the copolymer in the step of heat-treating the polyoxymethylene copolymer. For example, a quaternary ammonium compound may be injected into an extruder in which a polyoxymethylene copolymer is melt kneaded and extruded. Alternatively, when a filler or pigment is blended with the polyoxymethylene copolymer using the extruder or the like, a quaternary ammonium compound is first attached to the resin pellet of the polyoxymethylene copolymer, and is not added when the filler or pigment is blended thereafter. You may perform the decomposition removal process of a stable terminal part.

  The decomposition and removal treatment of the unstable terminal portion can be performed after the polymerization catalyst coexisting with the polyoxymethylene copolymer obtained by polymerization is deactivated, or can be performed without deactivating the polymerization catalyst. Is possible. Examples of the deactivation treatment of the polymerization catalyst include a method of neutralizing and deactivating the polymerization catalyst in a basic aqueous solution such as amines. When the polymerization catalyst is not deactivated, the polyoxymethylene copolymer is heated in an inert gas atmosphere at a temperature lower than the melting point of the polyoxymethylene copolymer, and the polymerization catalyst is reduced by volatilization. It is also effective to perform an operation of disassembling and removing the part.

  A polyoxymethylene copolymer having very excellent thermal stability can be obtained by the above-described decomposition and removal treatment of the unstable terminal portion.

  In the polyoxymethylene resin (A) constituting the polyoxymethylene resin composition, the amount of OH groups at the end relative to the total number of terminals of the molecule is preferably 5 to 95%. If the amount of OH groups at the end is 95% or less, it is preferable because microvoids can be intentionally formed during the production of the resin composition, and if the amount of OH groups at the end is 5% or more, it is preferable. (B) The adhesion of the modifying material can be improved. From the same viewpoint, the amount of OH groups at the end is more preferably 90% or less, still more preferably 85% or less, still more preferably 80% or less, and 6% or more. More preferably, it is 7% or more, more preferably 10% or more.

  The polyoxymethylene resin (A) constituting the polyoxymethylene resin composition preferably has an OH group amount at the terminal portion of 10 to 200 mmol / kg. If the terminal OH group amount is 200 mmol / kg or less, the thermal stability of the polyoxymethylene resin composition can be made very excellent during production, and if it is 10 mmol / kg or more, This is preferable because the crystallinity of the oxymethylene resin tends to increase. From the same viewpoint, the amount of OH groups at the end is more preferably 150 mmol / kg or less, further preferably 100 mmol / kg or less, still more preferably 90 mmol / kg or less, and 15 mmol / kg. It is more preferably not less than kg, more preferably not less than 20 mmol / kg, and still more preferably not less than 40 mmol / kg.

The amount of OH groups at the end can be measured directly and indirectly by ¹ H-NMR and ¹³ C-NMR.
In direct measurement, although not limited to the following methods, direct observation can be performed by two-dimensional NMR such as ¹ H-NMR and ¹³ C-NMR, a presaturation method, a WET method, and the like.
Indirect measurement is not limited to the following, but (A) Polyoxymethylene resin is dissolved in an NMR measurement solvent, and then derivatized with a silylating agent that can react with the OH group at the end. Can then be measured.

  Examples of the silylating agent include, but are not limited to, hexamethyldisilazane, dimethyldichlorosilane, trimethylchlorosilane, trimethylchlorosilane, N, O-bis (trimethylsilyl) acetamide, N-methyl-N-trimethylsilylacetamide, N-methyl-N-trimethylsilyltrifluoroacetamide, N-trimethylsilyldimethylamine, N-trimethylsilyldiethylamine, N, O-bis (trimethylsilyl) trifluoroacetamide, N-trimethylsilylimidazole, tert-butyldimethylchlorosilane, N-methyl-N -Tert-Butyldimethylsilyl trifluoroacetamide and the like can be used.

  The polyoxymethylene resin constituting the polyoxymethylene resin composition of the present embodiment includes (A) a polyoxymethylene homopolymer, a polyoxymethylene copolymer, a polyoxymethylene copolymer having a branch, and a polyoxymethylene copolymer having a crosslinked structure. Any of a homopolymer-based block copolymer having a block portion and a copolymer-based block copolymer having a block portion can be used, and these can be used in combination.

  Further, as the (A) polyoxymethylene resin, for example, combinations having different molecular weights, combinations of polyoxymethylene copolymers having different comonomer amounts, and the like can be used as appropriate.

In addition, the ratio of the copolymer or block copolymer in the molded article made of the polyoxymethylene resin composition of the present embodiment can be measured by ¹ H-NMR, ¹³ C-NMR, or the like.

Further, the structure of the block portion is obtained by dissolving a polyoxymethylene resin composition containing a block copolymer or a molded product thereof, and performing isolation such as reprecipitation or filtration, and then decomposing the block copolymer with hydrochloric acid. Thus, the block portion can be isolated and purified, and the block portion can be determined by performing various measurements such as ¹ H-NMR, ¹³ C-NMR, and two-dimensional NMR.

  (A) Although it does not specifically limit as a melt flow rate of a polyoxymethylene resin, It is preferable that the melt flow rate measured based on ISO-1133 condition D is 0.1-60 g / 10min. When the melt flow rate is 0.1 g / 10 min or more, it is preferable in terms of molding fluidity, and when it is 60 g / 10 min or less, the impact strength can be further improved. In addition, if the melt flow rate is within the above range, the modifying agent (B) can be uniformly dispersed in the polyoxymethylene resin composition of the present embodiment. From the same viewpoint, the melt flow rate of the (A) polyoxymethylene resin is more preferably 50 g / 10 min or less, further preferably 20 g / 10 min or less, and 10 g / 10 min or less. Is more preferable and 5 g / 10 min or less is particularly preferable. On the other hand, from the same viewpoint, the melt flow rate of the (A) polyoxymethylene resin is more preferably 0.2 g / 10 min or more, further preferably 0.5 g / 10 min or more, and 1 g / More preferably, it is 10 minutes or more, and particularly preferably 2 g / 10 or more.

(A) The melt viscosity of the polyoxymethylene resin is not particularly limited. For example, the (A) polyoxymethylene resin preferably has a viscosity of 100 to 4000 Pa · s when the shear rate at 190 ° C. is 100 sec ⁻¹ . If the said viscosity is in the said range, in the polyoxymethylene resin composition of this embodiment, (B) modifier can be disperse | distributed uniformly. The viscosity of the polyoxymethylene resin (A) at a 190 ° C. shear rate of 100 sec ⁻¹ is more preferably 3000 Pa · s or less, further preferably 2000 Pa · s or less, and 1500 Pa · s. Or less, more preferably 1000 Pa · s or less. On the other hand, the polyoxymethylene resin (A) has a viscosity at a shear rate of 190 ° C. of 100 sec ⁻¹ of more preferably 150 Pa · s or more, further preferably 200 Pa · s or more, and 300 Pa · s. More preferably, it is more preferably 400 Pa · s or more.

Further, for example, the polyoxymethylene resin (A) preferably has a viscosity of 50 to 2000 Pa · s when the shear rate at 190 ° C. is 1000 sec ⁻¹ . If the said viscosity is in the said range, in the polyoxymethylene resin composition of this embodiment, (B) modifier can be disperse | distributed uniformly. The viscosity of the polyoxymethylene resin (A) at a shear rate of 190 ° C. of 1000 sec ⁻¹ is more preferably 1500 Pa · s or less, further preferably 1000 Pa · s or less, and 500 Pa · s. Or less, more preferably 400 Pa · s or less. On the other hand, the polyoxymethylene resin (A) has a viscosity at a shear rate of 1000 sec ⁻¹ at 190 ° C. of preferably 60 Pa · s or more, more preferably 75 Pa · s or more, and 90 Pa · s. More preferably, it is more preferably 150 Pa · s or more.
The viscosity can be measured by a twin capillary rheometer (Malvern, Losand, RH10) or the like, and can be appropriately measured at a predetermined temperature and shear rate.

<(B) modifier>
The polyoxymethylene resin composition of this embodiment contains (B) a modifier. Moreover, (B) modifier contains (b-1) thermoplastic polyurethane and (b-2) graft rubber copolymer, (b-2) graft rubber copolymer has a structure of two or more layers. Have.

The polyoxymethylene resin composition of this embodiment contains 0.5 to 50 parts by mass of the (B) modifier with respect to 100 parts by mass of the (A) polyoxymethylene resin. By setting the content of component (B) to 0.5 parts by mass or more with respect to 100 parts by mass of component (A), the impact resistance tends to be improved, and the content is set to 50 parts by mass or less. Thus, the impact resistance tends to be improved while maintaining the rigidity.
From the same viewpoint, the content of the component (B) with respect to 100 parts by mass of the component (A) in the polyoxymethylene resin composition of the present embodiment is preferably 1 part by mass or more, and is 3 parts by mass or more. More preferably, the amount is 5 parts by mass or more, further preferably 45 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 35 parts by mass or less.

  In addition, in the polyoxymethylene resin composition of this embodiment, (A) polyoxymethylene resin and (B) modifier can form a sea-island structure. And this structure can be observed with apparatuses, such as an electron microscope (a transmission electron microscope (TEM), a scanning electron microscope (SEM)), and an optical microscope. These devices are common, and examples thereof include a transmission electron microscope H-7650 manufactured by Hitachi, Ltd.

  Moreover, those skilled in the art can easily discriminate between the (A) polyoxymethylene resin and the (B) modifier. Specifically, in the case of a transmission electron microscope, the color density of the screen due to the difference in electron beam transmission due to the molecular structure, the difference due to a staining agent such as osmium acid or ruthenium tetroxide, or the crystalline polymer It can be judged by the difference in the lamellar structure caused by.

In the present embodiment, (B) the modifying material can be isolated and purified from the polyoxymethylene resin composition by reprecipitation, separation after separation, etc., and the composition ratio, structure, molecular weight, etc. are calculated. It is possible. Further, for example, by performing various measurements such as ¹ H-NMR, ¹³ C-NMR, two-dimensional NMR, MALDI-TOF MS, GPC, etc., molecular structures such as repeating structures and branched structures, and positional information of various functional groups Etc. can be determined.

-(B-1) Thermoplastic polyurethane-
Thermoplastic polyurethane is a high molecular compound having a urethane bond in the main chain, and is an elastomer that can be processed thermoplastically. Examples of the polymer structure include a multi-block copolymer composed of a rigid urethane segment (hard segment) and a flexible diol segment (soft segment).

  Rigid urethane segments are obtained, for example, by reaction of polyfunctional isocyanates with what are known as chain extenders. As the polyfunctional isocyanate, aromatic diisocyanate, alicyclic diisocyanate, aliphatic diisocyanate, or the like can be used.

  Examples of the aromatic diisocyanate include 4,4′-diphenylmethane diisocyanate (MDI) and toluene diisocyanate (TDI) (for example, isomers such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate and mixtures thereof). , M-xylylene diisocyanate, p-xylylene diisocyanate, 1,5-naphthylene diisocyanate (NDI), 3,3′-dimethyl-4,4′-diphenylene diisocyanate (TODI), 2,2-diphenylpropane- 4,4 ″ -diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate and the like.

Examples of the alicyclic diisocyanate include 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI), isophorone diisocyanate (IPDI), cyclopentylene-1,3-diisocyanate, and the like.

  Examples of the aliphatic diisocyanate include 1,6-hexamethylene diisocyanate (HMDI) and 1,4-butylene diisocyanate.

  Examples of the chain extender (sometimes referred to as a crosslinking agent) include short-chain aliphatic, alicyclic or aromatic diols having a molecular weight (molar mass) of less than 500 g / mol, preferably less than 300 g / mol. , Diamines, and triols.

  Examples of diols include ethylene glycol, propylene 1,3-glycol, propylene 1,2-glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, and 1,6-hexane. Diol, 1,4-cyclohexanediol 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2butyl-1,3-propanediol, 2- Methyl-2,4-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, dihydroxy-cyclopentane, 1,4-cyclohexanedimethylol, thiodiglycol, diethylene glycol, dipropylene glycol, 2-methyl -1,3-propanediol, 2-methyl-2-ethyl-1,3-pro Njioru, dihydroxyethyl ether of hydroquinone, and the like hydrogenated bisphenol A. Examples of diamines include ethylenediamine, hexamethylenediamine, xylylenediamine, 4,4'-diaminodiphenylmethane, and the like. Examples of triols include trimethylolpropane and glycerin.

  Examples of the flexible diol segment include polyether diols, polyester diols, polyether ester diols, and polycarbonate diols having a number average molar mass of 500 to 5000 g / mol, preferably 1000 to 3000 g / mol. It is done.

  Examples of polyether diols include poly (tetramethylene ether) glycol (PTMEG), poly (propylene oxide) glycol, polybutadiene diol and copolymers thereof (for example, copolymers of propylene oxide and ethylene oxide, tetrahydrofuran and ethylene oxide, Copolymer). These can also be obtained, for example, by ring-opening polymerization of ethylene oxide, propylene oxide or tetrahydrofuran.

  Polyester diols include the above-mentioned polyether diols or dialcohols (for example, ethylene glycol, propylene 1,3-glycol, propylene 1,2-glycol, 1,4-butanediol, 1,3-butanediol, 2 -Methylpropanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, nonanediol, 1,10-decanediol, etc.) Obtained by esterification with dicarboxylic acids (for example, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, etc.) or by the corresponding transesterification reaction be able to. These polyester diols can also be obtained by ring-opening polymerization of lactones (for example, caprolactone, propiolactone, valerolactone, etc.).

  Polycarbonate diols include the above-mentioned polyether diols or dialcohols (for example, ethylene glycol, propylene 1,3-glycol, propylene 1,2-glycol, 1,4-butanediol, 1,3-butanediol, 2 -Methylpropanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, nonanediol, 1,10-decanediol, etc.) It can be obtained by reacting with diphenyl carbonates or phosgenes.

  (B-1) Examples of the thermoplastic polyurethane include ester polyurethane (sometimes referred to as “polyester polyurethane”), ether polyurethane (sometimes referred to as “polyether polyurethane”), Examples include ether ester polyurethane (sometimes referred to as “polyether ester polyurethane”) and caprolactone polyurethane (sometimes referred to as “polycaprolactone polyurethane”). In addition, (b-1) the thermoplastic polyurethane is preferably an ester polyurethane or an ether ester polyurethane, more preferably an ester polyurethane, from the viewpoint of sufficiently expressing impact resistance. Furthermore, the ester-based polyurethane preferably contains two kinds of polyol components (also referred to as “polyol units”) from the viewpoint of more sufficiently expressing impact resistance.

  (B-1) The hardness of the thermoplastic polyurethane falls within the range of about Shore A65 to about Shore D75. This hardness is determined by the ratio of rigid urethane segments to soft diol segments.

  (B-1) The melt index of thermoplastic polyurethane is measured at various temperatures and depends on the melting behavior of rigid urethane segments. This is also a measure of the degree of addition (molar mass of the entire chain).

  Moreover, by setting it as the following component ratio range, (b-1) thermoplastic polyurethane becomes suitable melt viscosity at the time of the process of a composition, and the improvement of impact resistance can be anticipated.

  The ether-based polyurethane has a ratio (mol ratio) of an ether diol component (also referred to as “ether diol unit”) when the isocyanate component (also referred to as “isocyanate unit”) is 1. 100 or less, more preferably 50 or less, further preferably 20 or less, more preferably 8 or more, more preferably 10 or more, and 13 or more. More preferably.

On the other hand, ester polyurethane, ether ester polyurethane, and carbonate polyurethane are ester components (also referred to as “ester units”) when the isocyanate component is 1, and carbonate components (also referred to as “carbonate units”). )) Ratio (mol ratio) is preferably 10 or less, more preferably 8 or less, further preferably 5 or less, and preferably 1 or more, It is more preferably 2 or more, further preferably 3 or more, and still more preferably 4 or more. By making the ratio of the ester component not more than the above upper limit, it tends to show good impact absorbability, and by making it not less than the above lower limit, better fluidity can be secured.
In addition, said ester component points out the component produced | generated when a carboxylic acid component and an isocyanate component react.

  In addition, in the ester polyurethane, ether ester polyurethane, and carbonate polyurethane, the ratio (mol ratio) of the polyol component when the isocyanate component is 1 is preferably 10 or less, and more preferably 8 or less. , 6 or less, more preferably 1 or more, more preferably 2 or more, further preferably 3 or more, and still more preferably 5 or more. By setting the ratio of the polyol component to the above upper limit or less, there is a tendency to exhibit a good sea-island structure, and by setting the ratio to the above lower limit or more, a better viscosity can be secured.

  The dispersed particle diameter of (b-1) thermoplastic polyurethane in the polyoxymethylene resin composition and the molded body comprising the resin composition is preferably 10 to 2000 nm in terms of equivalent circle diameter. (B-1) When the dispersed particle diameter of the thermoplastic polyurethane is 10 nm or more, good dispersibility is obtained, and impact resistance can be effectively expressed. Moreover, if the dispersion particle diameter of (b-1) thermoplastic polyurethane is 2000 nm or less, impact resistance can be expressed more fully. From the same viewpoint, the dispersed particle diameter of the (b-1) thermoplastic polyurethane in the molded product comprising the polyoxymethylene resin composition and the resin composition is more preferably 1500 nm or less in terms of equivalent circle diameter, It is further preferably 1000 nm or less, more preferably 800 nm or less, more preferably 30 nm or more, further preferably 40 nm or more, and further preferably 50 nm or more.

  In this specification, the equivalent circle diameter refers to the diameter of a circle having the same area as the calculated value of the product of the short diameter and diameter of the target substance to be projected. Further, the dispersed particle diameter of the target substance ((b-1) thermoplastic polyurethane, (b-2) graft rubber copolymer, etc.) in the molded body can be determined as follows. That is, the surface perpendicular to the resin flow direction of the molded body is observed with a transmission electron microscope or the like, and the short diameter and diameter of what is recognized as the dispersion domain of the target substance are measured. Next, the value of the product of the minor axis and the diameter is calculated, and the diameter of a circle having the same area as the value is obtained. And the diameter of the said circle is calculated | required about arbitrary 10 or more target substances, and what averaged them can be made into a dispersed particle diameter.

-(B-2) Graft rubber copolymer-
The graft rubber copolymer is a core-shell rubber, and is a polymer composed of a core layer and one or more shell layers covering the core layer. Here, the number of shell layers is not particularly limited, and may be two or more.

  (B-2) The component constituting the core layer of the graft rubber copolymer preferably has rubber elasticity in order to improve impact resistance. For example, acrylic polymer, silicone polymer, silicone / acrylic polymer Examples thereof include polymers, styrene polymers, nitrile polymers, conjugated diene polymers, urethane polymers, and olefin polymers. Moreover, the component which comprises the core layer of the (b-2) graft rubber copolymer is an acrylic polymer, a silicone polymer, a silicone / acrylic polymer, a conjugated diene polymer, and a urethane polymer. It is preferable. Among them, the component constituting the core layer of the (b-2) graft rubber copolymer is preferably a silicone polymer, an acrylic polymer, or a silicone / acrylic polymer from the viewpoint of impact resistance and heat aging resistance. .

  In addition, as a component constituting the core layer, rubber components obtained by polymerizing siloxane compounds such as dimethylsiloxane and phenylmethylsiloxane; acrylic compounds such as ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate; The copolymerization component of these components etc. are mentioned suitably.

  (B-2) As components constituting the outermost shell layer of the graft rubber copolymer, unsaturated carboxylic acid ester units, glycidyl group-containing vinyl units, aliphatic vinyl units, aromatic vinyl units, Examples thereof include a polymer containing a vinyl cyanide unit, a maleimide unit, an unsaturated dicarboxylic acid anhydride unit, or other vinyl units. Among these, from the viewpoint of impact resistance and heat aging resistance, a polymer containing a (meth) acrylic acid ester unit is preferable.

  The (b-2) graft rubber copolymer preferably has an Si element amount of 1 to 25% by mass in ICP-MS analysis from the viewpoint of thermal stability and rigidity during aging. Further, the amount of the Si element is not particularly limited, but is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, The content is more preferably 1.5% by mass or more, further preferably 2% by mass or more, and further preferably 2.5% by mass or more.

  (B-2) The method for producing the graft rubber copolymer is not particularly limited, and a known polymerization method, for example, a mixture containing a monomer and a polyfunctional vinyl monomer in a specific ratio, suspension polymerization, It can be obtained by a polymerization method such as emulsion polymerization.

  (B-2) The particle size of the graft rubber copolymer is preferably 20 to 2000 nm. (B-2) If the particle size of the graft rubber copolymer is 20 nm or more, the dispersibility during melt-kneading can be improved, and if it is 2000 nm or less, the resin composition can be handled during production. It can be made easier. From the same viewpoint, the particle size of the (b-2) graft rubber copolymer is more preferably 30 nm or more, further preferably 40 nm or more, further preferably 50 nm or more, and 1500 nm. Or less, more preferably 1000 nm or less, and still more preferably 800 nm or less.

  The dispersed particle diameter of the (b-2) graft rubber copolymer in the molded body is preferably 20 to 2000 nm in terms of equivalent circle diameter. (B-2) When the dispersed particle size of the graft rubber copolymer is 20 nm or more, good dispersibility is obtained, and impact resistance can be effectively expressed. Moreover, if the dispersed particle diameter of the (b-2) graft rubber copolymer is 2000 nm or less, the impact resistance can be more sufficiently exhibited. From the same viewpoint, the dispersed particle diameter of the (b-2) graft rubber copolymer in the molded body is more preferably 1500 nm or less, more preferably 1000 nm or less, and more preferably 800 nm or less in terms of equivalent circle diameter. More preferably, it is 30 nm or more, more preferably 40 nm or more, and further preferably 50 nm or more.

The mass ratio of the core layer and the shell layer of the (b-2) graft rubber copolymer is not particularly limited.
(B-2) The mass ratio of the core layer when the entire graft rubber copolymer is 100 parts by mass is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and 30 parts by mass. More preferably, it is the above. By setting the mass ratio of the core layer to be equal to or higher than the above lower limit, the chain entanglement between (b-2) graft rubber copolymers is reduced and the dispersibility can be further improved.

  The mass ratio of the core layer when the total amount of the (b-2) graft rubber copolymer is 100 parts by mass is preferably 95 parts by mass or less, more preferably 90 parts by mass or less, and 85 More preferably, it is at most part by mass. By setting the mass ratio of the core layer to the upper limit or less, the impact resistance can be further improved.

  (B-2) The graft rubber copolymer preferably has a sulfate ion concentration of 0.1 to 5 ppm. (B-2) If the concentration of sulfate ion in the graft rubber copolymer is 0.1 ppm or more, it is preferable because microvoids can be intentionally formed during melt-kneading, and if it is 5 ppm or less, Thermal stability can be further improved. From the same viewpoint, the concentration of sulfate ion in the (b-2) graft rubber copolymer is more preferably 4 ppm or less, further preferably 3 ppm or less, and further preferably 2.5 ppm or less. . Further, the concentration of sulfate ion in the (b-2) graft rubber copolymer is more preferably 0.2 ppm or more, further preferably 0.3 ppm or more, and further preferably 0.4 ppm or more. preferable.

  (B-2) The graft rubber copolymer preferably has a calcium ion concentration of 10 to 500 ppm. (B-2) If the concentration of calcium ions in the graft rubber copolymer is 10 ppm or more, it is preferable because microvoids can be intentionally formed at the time of melt-kneading. The sex can be further improved. From the same viewpoint, the concentration of calcium ions in the (b-2) graft rubber copolymer is more preferably 400 ppm or less, further preferably 350 ppm or less, further preferably 300 ppm or less, 15 ppm or more, more preferably 20 ppm or more, and further preferably 30 ppm or more.

  (B-2) Examples of commercially available graft rubber copolymers include “Metablene (registered trademark)” (manufactured by Mitsubishi Rayon Co., Ltd.), “Kane Ace (registered trademark)” (manufactured by Kaneka Corporation), and “STAPHYLOID (registered) Trademark) "(manufactured by Aika Kogyo Co., Ltd.), or" Parapet (registered trademark) SA "(manufactured by Kuraray Co., Ltd.)," PARALOID (registered trademark) "(manufactured by DOW)," Clearstrength (registered trademark) "(manufactured by ARKEMA) , “Durastrength (registered trademark)” (manufactured by ARKEMA), etc., and these may be used alone or in combination of two or more.

  Among these, as a commercial item of (b-2) graft rubber copolymer, metabrene, more specifically, S2001, S2006, S2030, S2100, S2200, S2501, SX-006, SRK-200, SX- 005 and MR-01 can be used more suitably.

<(C) Colorant>
The polyoxymethylene resin composition of this embodiment may contain (C) a colorant as an additional component (optional component). Here, (C) the colorant refers to a substance that changes the appearance by the action of absorption, scattering, reflection, etc. of visible light.

  The (C) colorant that can be present in the molded product of the polyoxymethylene resin composition in the present embodiment is important for further improving the wear resistance by combining with the component (B) in addition to the original coloring. Can have various roles. Then, from the viewpoint of obtaining excellent wear resistance, the (C) colorant can be contained in the polyoxymethylene resin composition of the present embodiment in an amount within the range described below.

  The reason why the wear resistance is improved by the presence of the colorant (C) is not clear, but it is considered that the surface hardness of the molded body is improved by the colorant (C).

  (C) Colorants include, but are not limited to, inorganic pigments and organic dyes and pigments.

Examples of the inorganic pigment include inorganic pigments generally used for coloring a resin. For example, an oxide of at least one metal selected from the group consisting of iron, zinc, and titanium, iron, zinc And at least one metal carbonate selected from the group consisting of titanium, zinc sulfide, titanium oxide, zinc oxide, iron oxide, barium sulfate, titanium dioxide, barium sulfate, hydrous chromium oxide, chromium oxide, cobalt aluminate, barite Powder, 1 type of zinc yellow, 2 types of zinc yellow, potassium ferrocyanide, kaolin, titanium yellow, cobalt blue, ultramarine blue, cadmium, nickel titanium, lithopone, strontium, amber, shenna, azurite, malachite, azuro malachite, Opiment, real gar, cinnabar, turquoise, chalcopyrite, yellow ocher, Rubert, Rosenna, Loamber, Cassel Earth, chalk, plaster, Burnt Shenna, Burnt Umber, Lapis lazuli, Azurite, Malachite, Coral powder, White mica, Cobalt blue, Cerulean blue, Cobalt violet, Cobalt green, Zinc white, Titanium white, Light Red, Chrome Oxide Green, Mars Black, Billijan, Yellow Ocher, Alumina White, Cadmium Yellow, Cadmium Red, Vermilion, Talc, White Carbon, Clay, Mineral Bio Red, Rose Cobalt Violet, Silver White, Gold Powder, Bronze Powder, Aluminum powder, Prussian blue, aureolin, talc, wollastonite, titanium mica, carbon black, acetylene bran Click, lamp black, furnace black, vegetable black, bone black, calcium carbonate, iron blue, and the like.
The “metal oxide” includes a “composite metal oxide” composed of two or more metals selected from iron, zinc, and titanium.

  In particular, as the colorant (C), an oxide of at least one metal selected from the group consisting of iron, zinc and titanium, a carbonate of at least one metal selected from the group consisting of iron, zinc and titanium, Zinc sulfide, zinc oxide, iron oxide, zinc yellow 1 type, zinc yellow 2 type, zinc white, titanium white, alumina white, talc, white carbon, silver white, carbon black, acetylene black, lamp black, furnace black, calcium carbonate Are preferred.

Among these, as the colorant (C), a colorant having a Mohs hardness of 8 or less is preferable from the viewpoint of wear resistance of the polyoxymethylene resin composition of the present embodiment. The (C) colorant preferably has a Mohs hardness of 7 or less, more preferably 6 or less.
In addition, the Mohs hardness of (C) the coloring agent can be measured with a Mohs hardness meter.

  Examples of organic dyes and pigments include, but are not limited to, condensed azo, quinone, phthalocyanine, monoazo, diazo, polyazo, anthraquinone, heterocyclic, pennon, quinacridone. Organic dyes such as thioindico, berylene, dioxazine, and phthalocyanine.

  In particular, as organic dyes and pigments, from the viewpoint of thermal stability of the polyoxymethylene resin composition of the present embodiment, condensed azo, quinone, phthalocyanine, anthraquinone, heterocyclic, pennon, quinacridone An organic dye / pigment based on thioindico, berylene, dioxazine or phthalocyanine is preferred. More preferred are condensed azo, quinone, phthalocyanine, anthraquinone, heterocyclic, pennon, quinacridone, berylene, or phthalocyanine organic dyes. More preferred are quinone, phthalocyanine, anthraquinone, heterocyclic, quinacridone, berylene, or phthalocyanine organic dyes.

It is preferable that the polyoxymethylene resin composition of this embodiment contains 0.01-3 mass parts of (C) coloring agent with respect to 100 mass parts of (A) polyoxymethylene resin. By setting the content of the component (C) to 0.01 parts by mass or more with respect to 100 parts by mass of the component (A), sufficient colorability can be provided to the polyoxymethylene resin composition, and 3 masses. By setting the amount to be no more than parts, the effect of improving the wear characteristics when the polyoxymethylene resin composition slides under a minute load can be sufficiently obtained.
From the same viewpoint, the content of the (C) colorant with respect to 100 parts by mass of the (A) polyoxymethylene resin in the polyoxymethylene resin composition of the present embodiment is more preferably 2.5 parts by mass or less. It is further preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, particularly preferably 1.0 part by mass or less, and most preferably 0.8 parts by mass or less. Moreover, it is more preferable that it is 0.05 mass part or more, and it is still more preferable that it is 0.1 mass part or more.

<Other additives>
The polyoxymethylene resin composition of the present embodiment is a conventionally known various stabilizer used in the polyoxymethylene resin composition as an additional component (optional component) as long as the object of the present invention is not impaired. The additive may be contained.

Examples of the stabilizer include, but are not limited to, antioxidants, scavengers such as formaldehyde and formic acid, and the like.
These may be used individually by 1 type and may be used in combination of 2 or more type.

As the antioxidant, a hindered phenol-based antioxidant is preferable from the viewpoint of improving the thermal stability of the polyoxymethylene resin composition of the present embodiment. It does not specifically limit as a hindered phenolic antioxidant, A well-known thing can be used suitably.
Examples of scavengers such as formaldehyde and formic acid are not limited to the following. For example, compounds containing formaldehyde-reactive nitrogen such as melamine and polyamide resins and polymers thereof, hydroxides of alkali metals or alkaline earth metals , Inorganic acid salts, and carboxylate salts. Specific examples include calcium hydroxide, calcium carbonate, calcium phosphate, calcium silicate, calcium borate, and fatty acid calcium salts (calcium stearate, calcium myristate, etc.). The fatty acid in the fatty acid calcium salt may be substituted with a hydroxyl group.

(A) It is preferable that content of antioxidant, for example, hindered phenolic antioxidant with respect to 100 mass parts of polyoxymethylene resin is 0.1-2 mass parts.
Moreover, it is preferable that content of the polymer containing the scavenger, for example, formaldehyde-reactive nitrogen with respect to 100 parts by mass of (A) polyoxymethylene resin is 0.1 to 3 parts by mass.
Moreover, it is preferable that content of the supplementary agent with respect to 100 mass parts of (A) polyoxymethylene resin, for example, the fatty-acid salt of alkaline-earth metal, is 0.1-1 mass part.

(Various properties of polyoxymethylene resin composition)
The polyoxymethylene resin composition of the present embodiment preferably has a sulfate ion concentration of 0.01 to 2.0 ppm. If the concentration of sulfate ions in the polyoxymethylene resin composition is 0.01 ppm or more, it is preferable because microvoids can be intentionally formed during melt-kneading, and if it is 2.0 ppm or less, it is thermally stable. The sex can be further improved. From the same viewpoint, the concentration of sulfate ions in the polyoxymethylene resin composition is more preferably 1.0 ppm or less, further preferably 0.8 ppm or less, and further preferably 0.7 ppm or less. It is particularly preferably 0.6 ppm or less, more preferably 0.02 ppm or more, further preferably 0.03 ppm or more, and further preferably 0.04 ppm or more.

  The polyoxymethylene resin composition of the present embodiment preferably has a calcium ion concentration of 2 to 100 ppm. If the concentration of calcium ions in the polyoxymethylene resin composition is 2 ppm or more, it is preferable because microvoids can be intentionally formed during melt-kneading, and if it is 100 ppm or less, thermal stability is further improved. Can be made. From a similar point of view. The concentration of calcium ions in the polyoxymethylene resin composition is more preferably 90 ppm or less, further preferably 80 ppm or less, further preferably 70 ppm or less, and more preferably 3 ppm or more. More preferably, it is 4 ppm or more, and further preferably 5 ppm or more.

(Production method of polyoxymethylene resin composition)
The polyoxymethylene resin composition of the present embodiment, for example, melts a predetermined amount of (A) polyoxymethylene resin and (B) modifier, and (C) a colorant and other additives as required. It can be obtained by kneading.

  Examples of the apparatus for obtaining the composition of the polyoxymethylene resin molded body of the present embodiment include known apparatuses such as a single-screw or multi-screw extruder, a roll, a Banbury mixer, etc. Among them, a decompression device and a side feeder. A twin screw extruder equipped with equipment and the like is particularly preferred.

  The method for mixing and melt-kneading the raw material components is not particularly limited, and methods known to those skilled in the art can be used. For example, (A) component and (B) component are all mixed in advance with a super mixer, tumbler, V-shaped blender, etc., and melt melt-kneaded with a twin screw extruder, and (A) component is a twin screw extruder. A method of adding the component (B) from the middle of the apparatus while being supplied to an apparatus such as a melt, and a part of the component (A) is supplied to an apparatus such as a twin-screw extruder, and the apparatus is melt-kneaded. Examples include a method of adding the remaining part of the component (A) and the component (B) from the middle of the process.

  When the polyoxymethylene resin composition of the present embodiment is produced by an apparatus such as the above-described extruder, the polyoxymethylene resin composition is obtained as a pellet and can be used for molding or the like. That is, a molded body can be obtained from the polyoxymethylene resin composition of the present embodiment.

(Use of polyoxymethylene resin composition and molded product)
The polyoxymethylene resin composition of the present embodiment and the molded body made of the polyoxymethylene resin composition can be suitably used for applications that require impact resistance. Specifically, although not limited to the following, for example, gears such as cams, sliders, levers, arms, clutches, felt clutches, idler gears, pulleys, rollers, rollers, key stems, key tops, shutters, reels, Mechanical parts represented by shafts, joints, shafts, bearings, guides, etc .; for office automation equipment represented by outsert molded resin parts, insert molded resin parts, chassis, trays, side plates, printers, and copiers Parts; parts for video equipment such as digital video cameras and digital cameras; CDs, DVDs, Blu-ray (registered trademark) Discs, other optical disk drives; music, video or information represented by navigation systems and mobile personal computers Equipment, mobile phone and fax Parts for communication equipment typified by; parts for electrical equipment, components for electronic devices, and the like.

  In addition, the polyoxymethylene resin composition of the present embodiment and the molded body made of the resin composition are automotive parts such as gasoline tanks, fuel pump modules, valves, gasoline tank flanges, etc. ; Door parts such as door locks, door handles, window regulators, speaker grills, etc .; Seat belt peripheral parts such as seat belt slip rings, press buttons, etc .; Combination switch parts, switches, clips, etc. Applicable to parts.

  Further, the polyoxymethylene resin composition of the present embodiment and the molded body made of the resin composition include, for example, a pen part of a writing instrument, a mechanism part for taking in and out a core; a wash basin, a drain outlet, And drain valve opening / closing mechanism parts; cord stoppers for clothing, adjusters, buttons; nozzles for water spraying, sprinkling hose connection joints; building supplies that support stair railings and floor materials; toys, fasteners, chains, conveyors, It can also be suitably used as a buckle, sporting goods, vending machine (opening / closing part locking mechanism, product discharge mechanism part), furniture, musical instrument, housing equipment part.

  The polyoxymethylene resin composition of the present embodiment and the molded body made of the resin composition can be applied to various uses where polyoxymethylene has been suitably used so far, and have high industrial use. It has a possibility.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited only to these Examples.

<Preparation or preparation of raw material components>
(A) Polyoxymethylene resins were prepared as shown below, and the following (b-1) thermoplastic polyurethane and (b-2) graft rubber copolymer were used.

(1) Polyoxymethylene resin (A-1)
A biaxial self-cleaning type polymerization machine with a jacket through which a heat medium can pass (L / D = 8 (L: distance (m) from the raw material supply port to the discharge port of the polymerization machine, D: inner diameter of the polymerization machine ( m).) was adjusted to 80 ° C. To this polymerizer, trioxane was 4 kg / hour, 1,3-dioxolane as a comonomer was 200 g / hour, and methylal as a chain transfer agent was 1 per 1 mole of trioxane. .8 × 10 ⁻³ moles were added continuously.

Furthermore, boron trifluoride di-n-butyl etherate as a polymerization catalyst was continuously added to the polymerization machine in an amount of 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane, and polymerization was performed. The polyoxymethylene copolymer discharged from the polymerization machine was put into a triethylamine 0.1% aqueous solution to deactivate the polymerization catalyst.

  After the deactivated polyoxymethylene copolymer is filtered with a centrifuge, 1 part by mass of an aqueous solution containing a quaternary ammonium compound is added to 100 parts by mass of the polyoxymethylene copolymer and mixed uniformly. Supplyed to a twin screw extruder with a vent, 0.5 parts by weight of water is added to 100 parts by weight of the melted polyoxymethylene copolymer in the extruder. The unstable end of the polyoxymethylene copolymer was decomposed and removed at a residence time of 7 minutes. At this time, the addition amount of the quaternary ammonium compound was 20 mass ppm in terms of the nitrogen amount.

  Polyoxymethylene copolymer with unstable terminal ends decomposed into triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] 0.3 as an antioxidant A part by mass was added and extruded from a die part of the extruder as a strand while devolatilizing under a condition of a vacuum degree of 20 Torr with an extruder equipped with a vent to form pellets.

  The polyoxymethylene copolymer thus obtained was designated as polyoxymethylene resin (A-1). The melt flow rate of the polyoxymethylene resin (A-1) was 9 g / 10 min (ISO-1133 condition D).

Also relates to the melt viscosity of the polyoxymethylene resin (A-1), the viscosity at a 190 ° C. of shear rate 100 sec ^-1, a 550 Pa · s, the viscosity at a 190 ° C. of shear rate of 1,000 sec ^-1, It was 250 Pa · s.

(2) Polyoxymethylene resin (A-2)
A biaxial self-cleaning type polymerization machine with a jacket through which a heat medium can pass (L / D = 8 (L: distance (m) from the raw material supply port to the discharge port of the polymerization machine, D: inner diameter of the polymerization machine ( m).) was adjusted to 80 ° C. To this polymerizer, trioxane was 4 kg / hour, 1,3-dioxolane as a comonomer was 200 g / hour, and methylal as a chain transfer agent was 1 per 1 mole of trioxane. . Continuously added in an amount of 10 x ^10-3 moles.

Furthermore, boron trifluoride di-n-butyl etherate as a polymerization catalyst was continuously added to the polymerization machine in an amount of 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane, and polymerization was performed. The polyoxymethylene copolymer discharged from the polymerization machine was put into a triethylamine 0.1% aqueous solution to deactivate the polymerization catalyst.

  After the deactivated polyoxymethylene copolymer is filtered with a centrifuge, 1 part by mass of an aqueous solution containing a quaternary ammonium compound is added to 100 parts by mass of the polyoxymethylene copolymer and mixed uniformly. Supplyed to a twin screw extruder with a vent, 0.5 parts by weight of water is added to 100 parts by weight of the melted polyoxymethylene copolymer in the extruder. The unstable end of the polyoxymethylene copolymer was decomposed and removed at a residence time of 7 minutes. At this time, the addition amount of the quaternary ammonium compound was 20 mass ppm in terms of the nitrogen amount.

  Polyoxymethylene copolymer with unstable terminal ends decomposed into triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] 0.3 as an antioxidant A part by mass was added and extruded as a strand from a die part of the extruder while being devolatilized under a condition of a vacuum degree of 20 Torr with an extruder equipped with a vent to form pellets.

  The polyoxymethylene copolymer thus obtained was designated as polyoxymethylene resin (A-2). The melt flow rate of the polyoxymethylene resin (A-2) was 3 g / 10 min (ISO-1133 condition D).

Also relates to the melt viscosity of the polyoxymethylene resin (A-2), the viscosity at a 190 ° C. of shear rate 100 sec ^-1, a 900 Pa · s, the viscosity at a 190 ° C. of shear rate of 1,000 sec ^-1, 350 Pa · s.

(3) Polyoxymethylene resin (A-3)
A biaxial self-cleaning type polymerization machine with a jacket through which a heat medium can pass (L / D = 8 (L: distance (m) from the raw material supply port to the discharge port of the polymerization machine, D: inner diameter of the polymerization machine ( m).) was adjusted to 80 ° C. In this polymerization machine, trioxane was 4 kg / hour, 1,3-dioxolane as a comonomer was 200 g / hour, and methylal as a chain transfer agent was 3 per 1 mole of trioxane. Added continuously in an amount of 0.0 × 10 ⁻³ mol.

Furthermore, boron trifluoride di-n-butyl etherate as a polymerization catalyst was continuously added to the polymerization machine in an amount of 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane, and polymerization was performed. The polyoxymethylene copolymer discharged from the polymerization machine was put into a triethylamine 0.1% aqueous solution to deactivate the polymerization catalyst.

  After the deactivated polyoxymethylene copolymer is filtered with a centrifuge, 1 part by mass of an aqueous solution containing a quaternary ammonium compound is added to 100 parts by mass of the polyoxymethylene copolymer and mixed uniformly. Supplyed to a twin screw extruder with a vent, 0.5 parts by weight of water is added to 100 parts by weight of the melted polyoxymethylene copolymer in the extruder. The unstable end of the polyoxymethylene copolymer was decomposed and removed at a residence time of 7 minutes. At this time, the addition amount of the quaternary ammonium compound was 20 mass ppm in terms of the nitrogen amount.

  Polyoxymethylene copolymer with unstable terminal ends decomposed into triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] 0.3 as an antioxidant A part by mass was added and extruded from a die part of the extruder as a strand while devolatilizing under a condition of a vacuum degree of 20 Torr with an extruder equipped with a vent to form pellets.

  The polyoxymethylene copolymer thus obtained was designated as polyoxymethylene resin (A-3). The melt flow rate of the polyoxymethylene resin (A-3) was 45 g / 10 min (ISO-1133 condition D).

Also relates to the melt viscosity of the polyoxymethylene resin (A-3), the viscosity at a 190 ° C. of shear rate 100 sec ^-1, a 350 Pa · s, the viscosity at a 190 ° C. of shear rate of 1,000 sec ^-1, 100 Pa · s.

(4) Thermoplastic polyurethane (b-1-1)
A commercially available ester-based polyurethane (ESTANE: registered trademark) composed of repeated hard segments and soft segments was used. The molar ratio of each composition is diphenylmethane diisocyanate (isocyanate component): adipic acid (ester component): tetramethylene glycol (polyol component): ethylene glycol (polyol component) = 1: 4.5: 3.3: 2.2 there were.

(5) Thermoplastic polyurethane (b-1-2)
A commercially available ether-based polyurethane (RESAMINE: registered trademark) composed of repeated hard segments and soft segments was used. The molar ratio of each composition was diphenylmethane diisocyanate: tetramethylene glycol = 1: 8.8.

(6) Thermoplastic polyurethane (b-1-3)
A commercially available caprolactone-based polyurethane (Milactolan: registered trademark) composed of repeated hard segments and soft segments was used. The molar ratio of each composition was diphenylmethane diisocyanate: tetramethylene glycol: polycaprolactone polyol = 1: 1: 3.
These can be adjusted by the method described in WO2011125540.

(7) Graft rubber copolymer (b-2-1)
Commercially available methabrene S2100 was used. The amount of Si element in this graft rubber copolymer was 2.9% by mass.

(8) Graft rubber copolymer (b-2-2)
Commercially available Methbrene S2006 was used. The amount of Si element in this graft rubber copolymer was 3.5% by mass.

(9) Graft rubber copolymer (b-2-3)
Commercially available methabrene S2030 was used. The amount of Si element in this graft rubber copolymer was 11.1% by mass.

(10) Graft rubber copolymer (b-2-4)
A commercially available KANE ACE MR-01 was used. The amount of Si element in this graft rubber copolymer was 27% by mass.

(11) Graft rubber copolymer (b-2-5)
Commercially available methabrene C223A was used.

(12) Graft rubber copolymer (b-2-6)
Commercially available methabrene E875A was used.

(13) Graft rubber copolymer (b-2-7)
Commercially available KANE ACE FM-53 was used.

<Preparation of polyoxymethylene resin composition and production of molded article>
A polyoxymethylene resin composition was prepared and a molded body was produced according to the following procedure.

(1) Preparation of polyoxymethylene resin composition According to the formulation shown in Tables 1 and 2, using an extruder (TEM-26SS extruder manufactured by Toshiba Machine Co., Ltd. (L / D = 48, with vent)) The cylinder temperature was all set to 200 ° C., and the pellet corresponding to 90 parts by mass of the component (A) and the component (b-2) were supplied from the main feeder at the top of the extruder independently from the quantitative feeder. In addition, the pellet corresponding to 10 parts by mass of the component (A) and the component (b-1) were separately supplied from the feeder side part from the side of the extruder, and the component (C), other additives, etc. Were added together with pellets corresponding to 90 parts by mass of component (A), and supplied alone from the main throat of the top of the extruder, with an extrusion rate of 15 kg / hour and a screw speed of 150 rp. The resin kneaded product was extruded into a strand shape under the conditions of m, quenched with a strand bath, and cut with a strand cutter to obtain a pellet-shaped polyoxymethylene resin composition.

(2) Production of multi-purpose test piece molded body From the obtained pellet-shaped polyoxymethylene resin composition, using an injection molding machine (Toshiba Machine Co., Ltd., EC-75NII), the cylinder temperature was 205 ° C, gold The mold temperature was set to 60 ° C., and molding was performed under injection conditions of an injection time of 35 seconds and a cooling time of 15 seconds to obtain a multipurpose test piece molded body conforming to ISO294-1.

(3) Production of flat molded body From the obtained pellet-shaped polyoxymethylene resin composition, using an injection molding machine (EC-75NII, manufactured by Toshiba Machine Co., Ltd.), the cylinder temperature was 205 ° C and the mold temperature. Was set to 60 ° C. and molded under injection conditions of an injection time of 35 seconds and a cooling time of 15 seconds to obtain a flat plate molded product having a thickness of 3 mm, a length of 75 mm, and a width of 50 mm.

<Characteristic evaluation>
Various characteristics were evaluated according to the following procedures using the obtained pellet-shaped polyoxymethylene resin composition or molded article.

(1) Notched Charpy impact strength (23 ° C)
Using the obtained multipurpose test piece molded body, measurement was performed in accordance with ISO179-1. The results are shown in Tables 1 and 2. The larger the value, the better the impact resistance.

(2) Charpy impact strength with low temperature notch (-30 ° C)
Using the obtained multi-purpose test piece molded body, measurement was performed according to ISO 179-1 in a state cooled to −30 ° C. The results are shown in Tables 1 and 2. It was judged that the larger the value, the better the impact strength at low temperature.

(3) Dirt impact strength (23 ° C)
The total absorption energy at the time of flat plate fracture | rupture was measured by the INSTRON company make and CREAT 9340 using the obtained flat plate molded object. The measurement was performed n = 10 times, and the average value of 6 points obtained by excluding the maximum value of 2 points and the minimum value of 2 points was calculated. The results are shown in Tables 1 and 2. It was judged that the greater the value, the better the dart impact strength.

(4) Tensile modulus Using the obtained multipurpose test piece molded body, measurement was performed in accordance with ISO527. The larger the value, the better the rigidity. The results are shown in Tables 1 and 2. The greater the value, the better the rigidity.

(5) Friction coefficient Using a ball-on-disk type reciprocating friction and wear tester (AFT-15MS type, manufactured by Toyo Seimitsu Co., Ltd.), the load is 19.6 N and the linear velocity is 30 mm in an environment of 23 ° C. and a humidity of 50%. / Sec, a reciprocating distance of 20 mm, and a reciprocating frequency of 10,000 times, a sliding test on the surface of the obtained multipurpose test piece molded body was performed. As the ball material, SUS304 balls (spheres with a diameter of 5 mm) were used. The friction coefficient when the number of reciprocations reached 10,000 was measured. The results are shown in Tables 1 and 2. The smaller the value, the better the slidability.

(6) Thermal residence limit time From the obtained pellet-shaped polyoxymethylene resin composition, using an injection molding machine (Toshiba Machine Co., Ltd., EC-75NII), the cylinder temperature is 210 ° C. and the mold temperature is A multipurpose test piece molded body conforming to ISO294-1 was obtained by molding at an injection condition of 30 ° C. and injection time of 35 seconds and cooling time of 15 seconds. After molding 10 shots, with the resin plasticized in the cylinder, the molding operation is stopped while the heater is still heated. After a predetermined time, the molding is started again, and the silver streak on the first molded body is stopped. The occurrence status was confirmed. Confirmation of the occurrence of silver streaks was carried out at 10 minutes, 20 minutes, 30 minutes, 40 minutes, and 50 minutes when the molding machine was stopped. The time when silver streaks appeared on the entire surface of the molded body was defined as the heat retention limit time in the cylinder. The results are shown in Tables 1 and 2. The longer the limit time, the better the thermal stability.

(7) Tensile strength retention after aging The long-term thermal stability evaluation was performed using the obtained multipurpose test piece molded body. Specifically, the multi-purpose test piece molded body was placed in a gear oven in a 145 ° C. environment and exposed to a high heat environment for 35 days. After 35 days, the sample was taken out, and after 24 hours, the tensile strength was measured by a method according to ISO 527-1. The tensile strength before exposure was compared with the tensile strength after exposure, and the strength retention was calculated. The results are shown in Tables 1 and 2. It was judged that the closer this value was to 100, the better.

  From Table 1 and Table 2, it contains (A) a polyoxymethylene resin, and (b-1) a thermoplastic polyurethane and (b-2) a modifying rubber containing a graft rubber copolymer. ) The content of the modifier is 0.5 to 50 parts by mass with respect to 100 parts by mass of (A) polyoxymethylene resin, and (b-1) thermoplastic polyurethane and (b-2) graft rubber The polyoxymethylene resin composition according to the example in which the ratio of (b-1) thermoplastic polyurethane in the total copolymer is 17 to 95% by mass is impact resistance, impact strength at low temperature, dart impact strength, It can be seen that both rigidity and slidability are good.

  According to the present invention, it is possible to provide a polyoxymethylene resin composition that is excellent in impact resistance, rigidity, and slidability and excellent in low-temperature impact strength and dirt impact strength. Further, according to the present invention, it is possible to provide a molded article that is excellent in impact resistance, rigidity, and slidability, and that is excellent in low-temperature impact strength and dart impact strength.

Claims (10)

(A) containing 100 parts by mass of a polyoxymethylene resin and (B) 0.5 to 50 parts by mass of a modifier,
The (B) modifier includes (b-1) a thermoplastic polyurethane and (b-2) a graft rubber copolymer,
The (b-2) graft rubber copolymer has a structure of two or more layers,
The ratio of the (b-1) thermoplastic polyurethane in the total of the (b-1) thermoplastic polyurethane and the (b-2) graft rubber copolymer is 17 to 95% by mass.
The polyoxymethylene resin composition characterized by the above-mentioned.   The polyoxymethylene resin composition according to claim 1, wherein the (b-1) thermoplastic polyurethane is an ester-based polyurethane.   3. The ester-based polyurethane has an ester component ratio (mol ratio) of 4 to 5 when the isocyanate component is 1, and a polyol component ratio (mol ratio) of 5 to 6. Polyoxymethylene resin composition.   The polyoxymethylene resin composition according to claim 2 or 3, wherein the ester-based polyurethane contains two types of polyol components.   The polyoxymethylene resin composition according to any one of claims 1 to 4, wherein the (b-2) graft rubber copolymer has an amount of Si element of 1 to 25 mass% in ICP-MS analysis. .   The (b-2) graft rubber copolymer includes a silicone / acrylic polymer, and the amount of Si element in ICP-MS analysis is 2 to 10% by mass. The polyoxymethylene resin composition according to one item.   The polyoxymethylene resin composition according to any one of claims 1 to 6, wherein the concentration of sulfate ions is 0.01 to 0.2 ppm.   The polyoxymethylene resin composition according to any one of claims 1 to 7, wherein the (A) polyoxymethylene resin has a melt flow rate of 0.1 to 60 g / 10 min.   The polyoxymethylene resin composition according to any one of claims 1 to 8, which has a pellet shape.   A molded article comprising the polyoxymethylene resin composition according to any one of claims 1 to 9.