JP6373727B2 - Resin molded body - Google Patents

Description

  The present invention relates to a resin molded body.

  The polyacetal resin has an excellent balance of mechanical strength, chemical resistance, slidability, and wear resistance, and is easy to process. Therefore, as typical engineering plastics, it is widely used for mechanical parts of electric equipment, automobile parts, and other mechanical parts. In particular, a polyacetal composition reinforced with an inorganic filler is used for automobile mechanism parts that require long-term durability. In order to improve long-term characteristics such as creep properties and vibration fatigue characteristics, it is effective to use a high molecular weight polyacetal resin.

  For example, Patent Document 1 discloses that a fiber-reinforced polyacetal resin composition containing a polyacetal resin and a fibrous inorganic filler is suitable for improving the fracture life (creep characteristics) under a constant stress. There is also a disclosure that the higher the molecular weight of the polyacetal resin, the better the creep resistance, which is preferable.

  For example, in Patent Document 2, it is preferable that the composition for a fuel component having excellent creep resistance, conductivity, and thermal stability is made of polyacetal resin, glass fiber, conductive carbon, and the like, and has specific physical properties. There is a disclosure. In Patent Document 2, as in Patent Document 1, there is a disclosure that the higher the molecular weight of the polyacetal resin, the better the creep characteristics.

  By the way, in response to the recent trend of improving fuel efficiency in automobiles, parts made of polyacetal resin are also required to be reduced in weight by being thinned.

JP-A-11-181231 Japanese Patent Laid-Open No. 11-1603

  However, if a high molecular weight polyacetal resin is used to maintain long-term characteristics such as creep properties even after thinning, poor filling occurs during molding.

  Moreover, the slidability is not sufficient in the parts obtained from the conventional resin composition. For example, when a conventional resin composition is used for a part that comes into contact with another part, such as a gear or a pulley, the other part is worn or damaged.

  Then, an object of this invention is to provide the resin molding which can satisfy the outstanding thin moldability and high creep property simultaneously.

  As a result of intensive studies to solve the problems of the prior art, the present inventors have found that a resin molded article containing a polyacetal resin and a specific range of specific glass fibers and having a specific range of melt flow rate is the above-described problem. As a result, the present invention has been completed.

That is, the present invention is as follows.
[1] (A) polyacetal resin, and (A) 10 mass parts or more and 100 mass parts or less of (B) glass fiber with respect to 100 mass parts of polyacetal resin,
(B) The average fiber diameter of the glass fiber is 7 μm or more and 13 μm or less, the number average fiber length is 150 μm or more and 350 μm or less,
(B) Glass fiber 100 mass%, fiber length 50 μm or less (B) glass fiber is 30 mass% or less,
A resin molded article having a melt flow rate (ISO 1133 compliant, temperature 190 ° C., load 2.16 kg) of 10 g / 10 min or more and 30 g / 10 min or less.
[2] The resin molded article according to [1], wherein the number average molecular weight of the (A) polyacetal resin is 20,000 or more and 70,000 or less.
[3] The melt flow rate of (A) polyacetal resin (ISO 1133 compliant, temperature 190 ° C., load 2.16 kg) is 10 g / 10 min or more and 100 g / 10 min or less, according to [1] or [2] Resin molded body.
[4] The resin molded body according to any one of [1] to [3], wherein the (A) polyacetal resin is a block copolymer.
[5] The resin molding as described in any one of [1] to [4], further including 0.01 to 5 parts by mass of (C) polyolefin resin with respect to 100 parts by mass of (A) polyacetal resin. body.
[6] (C) Polyethylene resin, polyethylene, polypropylene, ethylene-α-olefin copolymer, ethylene-acrylic acid ester copolymer containing 5% by mass or more and 30% by mass or less of an acrylic acid ester unit, a block of polyolefin, A block copolymer having a structure in which a hydrophilic polymer block is repeatedly and alternately bonded via at least one bond selected from the group consisting of an ester bond, an amide bond, an ether bond, a urethane bond and an imide bond, and these The resin molded product according to [5], which is at least one selected from the group consisting of a modified product.

  According to the resin molded body of the present invention, a resin molded body that achieves both excellent thin-wall molding and high creep properties can be obtained.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and the present invention is not limited to the following contents. The present invention can be implemented with various modifications within the scope of the gist.

[Resin molding]
The resin molded body of this embodiment (hereinafter also referred to as “polyacetal resin molded body”) is (A) polyacetal resin and (A) 100 mass parts of polyacetal resin (B) 10 mass parts or more and 100 mass parts of glass fiber. (B) the average fiber diameter of the glass fiber is 7 μm or more and 13 μm or less, the number average fiber length is 150 μm or more and 350 μm or less, and (B) the fiber length is 50 μm or less with respect to 100% by mass of the glass fiber. (B) glass fiber is 30 mass% or less, and melt flow rate (ISO1133 conformity, temperature 190 ° C., load 2.16 kg) is 10 g / 10 min or more and 30 g / 10 min or less.

  The resin molded body of the present embodiment has a melt flow rate (ISO 1133 compliant, temperature 190 ° C., load 2.16 kg) (hereinafter simply abbreviated as MFR) within a specific range. Specifically, it exists in the range of 10 g / 10min or more and 30g / 10min or less. By setting the MFR to 10 or more, the thin-wall formability tends to increase. Moreover, it is in the tendency which suppresses a rapid fall of a creep characteristic by making MFR 30 or less. The MFR of the resin molded body is confirmed by, for example, finely cutting the resin molded body to obtain a pellet-shaped sample by measuring the above MFR.

  The fluidity (MFR) of the resin molded product is the molecular weight of the (A) polyacetal resin contained in the resin molded product, the MFR value, etc., and the (B) glass fiber content, fiber length, fiber diameter contained in the resin molded product. Affected by various factors such as

  Moreover, in the resin molded body of this embodiment, even if MFR has high fluidity of 10 g / 10 min or more, from the viewpoint of maintaining high creep properties, for example, the form of glass fiber contained in the resin molded body Is a specific form.

  The polyacetal resin molded product in the present embodiment includes all molded products molded by various methods. Specific examples include injection-molded molded articles, extrusion-molded and inflation-molded molded articles (sheets, films, strands, pellets, etc.), blow-molded molded articles, and the like.

<(A) polyacetal resin>
The (A) polyacetal resin (in this specification, it may be described as (A) component and (A)) which can be used in the resin molding of this embodiment is demonstrated in detail.

  In this embodiment, in order that MFR of a resin molding exists in the range of 10 g / 10min or more and 30 g / 10min or less, the molecular weight of (A) polyacetal resin contained in a resin molding influences at least.

  (A) Even if a high molecular weight polyacetal resin is used as the polyacetal resin, it is possible to improve the fluidity and to improve the thin moldability by making the glass fiber into a specific form. However, in order to obtain better thin-wall moldability, it is preferable that the molecular weight of the (A) polyacetal resin is within an appropriate range. Specifically, it is preferable that (A) the polyacetal resin has a number average molecular weight (hereinafter sometimes simply referred to as Mn) of 20,000 or more and 70,000 or less.

  The upper limit of the number average molecular weight is more preferably 60,000, further preferably 55,000, and particularly preferably 50,000. Further, the lower limit of the number average molecular weight is more preferably 25,000, further preferably 28,000, and particularly preferably 30,000. By setting the number average molecular weight to 70,000 or less, the thin moldability tends to be exhibited. Moreover, it exists in the tendency which can suppress a rapid fall of a creep characteristic by making a number average molecular weight or more into 20,000.

  Here, the number average molecular weight is obtained by cutting out a part of a resin molded article, using a polyacetal resin component dissolved in hexafluoroisopropanol (hereinafter abbreviated as HFIP) as a sample, and using hexafluoroisopropanol as a solvent. It is a number average molecular weight represented by PMMA equivalent molecular weight calculated by gel permeation chromatography (hereinafter abbreviated as GPC) using polymethyl methacrylate (hereinafter abbreviated as PMMA) as a standard substance. In this case, the PMMA standard substance has a number average molecular weight of at least 4 samples in the range of about 2,000 to about 1,000,000.

  As MFR of (A) polyacetal resin in this embodiment, it is preferable that they are 10 g / 10min or more and 100 g / 10min or less. A more preferred lower limit is 15 g / 10 minutes, even more preferably 18 g / 10 minutes, and particularly preferably 20 g / 10 minutes. Moreover, a preferable upper limit is 80 g / 10 minutes, More preferably, it is 60 g / 10 minutes, More preferably, it is 50 g / 10 minutes. By setting the MFR to 10 g / 10 min or more, the thin-wall moldability tends to be further improved. Moreover, it exists in the tendency which can suppress a rapid fall of creep property by making MFR into 100 g / 10min or less.

  Here, for example, a polyacetal resin having an MFR of 10 g / 10 min has a slight difference depending on its molecular weight distribution, but it is about 70,000 in terms of number average molecular weight. For example, a polyacetal resin having an MFR of 100 g / 10 min is about 20,000 in terms of number average molecular weight.

  In the present embodiment, examples of the (A) polyacetal resin include polyacetal homopolymers and polyacetal copolymers. Specifically, a polyacetal homopolymer consisting essentially of oxymethylene units obtained by homopolymerizing formaldehyde monomer or a cyclic oligomer of formaldehyde such as trimer (trioxane) or tetramer (tetraoxane); Monomers or cyclic oligomers of formaldehyde such as trimer (trioxane) or tetramer (tetraoxane), and glycols such as ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane, 1,4-butanediol formal Or the polyacetal copolymer etc. which are obtained by copolymerizing cyclic ethers, such as cyclic formal of diglycol, or cyclic formal, etc. are mentioned.

  Also obtained as a polyacetal copolymer by copolymerizing formaldehyde monomers and / or cyclic oligomers of formaldehyde with monofunctional glycidyl ethers and branched polyacetal copolymers, and polyfunctional glycidyl ethers. And a polyacetal copolymer having a crosslinked structure.

  Furthermore, the block copolymer etc. which have a different block different from the repeating structural unit of a polyacetal are mentioned. (A) The polyacetal resin is preferably a block copolymer. As the block copolymer here, an acetal homopolymer having a block portion represented by the following general formula (1), (2) or (3), or an acetal copolymer (both are also referred to as “block copolymer” hereinafter). ) Is more preferable.

式（１）及び（２）中、Ｒ₁、Ｒ₂及びＲ₃は、それぞれ独立に、水素原子、アルキル基、置換アルキル基、アリール基及び置換アリール基からなる群より選ばれる１種の化学種を示し、複数のＲ₁、Ｒ₂、及びＲ₃は、それぞれ同一であっても異なっていてもよい。ｍは２〜６の整数を示し、２〜５の整数が好ましい。ｎは１〜１０００の整数を示し、１０〜２５０の整数が好ましい。上記一般式（１）で表される基は、アルコールのアルキレンオキシド付加物から水素原子を脱離した残基であり、上記一般式（２）で表される基は、カルボン酸のアルキレンオキシド付加物から水素原子を脱離した残基である。前記ブロック成分を有するポリアセタールホモポリマーは、例えば、特開昭５７−３１９１８号公報に記載の方法で調製できる。

In formulas (1) and (2), R ₁ , R ₂ and R ₃ are each independently one chemistry selected from the group consisting of a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group and a substituted aryl group. A seed is shown, and a plurality of R ₁ , R ₂ , and R ₃ may be the same or different. m shows the integer of 2-6, and the integer of 2-5 is preferable. n shows the integer of 1-1000, and the integer of 10-250 is preferable. The group represented by the general formula (1) is a residue obtained by eliminating a hydrogen atom from an alkylene oxide adduct of alcohol, and the group represented by the general formula (2) is an alkylene oxide addition of a carboxylic acid. It is a residue obtained by removing a hydrogen atom from a product. The polyacetal homopolymer having the block component can be prepared, for example, by the method described in JP-A-57-31918.

式（３）中、Ｒ₄は、水素原子、アルキル基、置換アルキル基、アリール基及び置換アリール基からなる群より選ばれる１種の化学種を示し、複数のＲ₄はそれぞれ同一であっても異なっていてもよい。また、ｐは２〜６の整数を示し、２つのｐは各々同一であっても異なっていてもよい。ｑ、ｒはそれぞれ正の数を示し、ｑとｒとの合計１００モル％に対してｑは２モル％以上１００モル％以下、ｒは０モル％以上９８モル％以下であり、−（ＣＨ（ＣＨ₂ＣＨ₃）ＣＨ₂）−単位及び−（ＣＨ₂ＣＨ₂ＣＨ₂ＣＨ₂）−単位はそれぞれランダム又はブロックで存在する。

In Formula (3), 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 the plurality of R ₄ are the same. May be different. P represents an integer of 2 to 6, and two ps may be the same or different. q and r each represent a positive number, with respect to a total of 100 mol% of q and r, q is 2 mol% or more and 100 mol% or less, r is 0 mol% or more and 98 mol% or less, and — (CH _{(CH 2 CH 3) CH 2} ) - units and _{- (CH 2 CH 2 CH 2} CH 2) - units are present in random or block respectively.

  The block portion of the block copolymer represented by the above formulas (1) to (3) is a compound comprising a block having a functional group such as a hydroxyl group at both ends or one end, and a polyacetal resin in the polymerization process of the polyacetal resin. It can be obtained by reacting with the terminal portion.

  The amount of the block component represented by the above formula (1), (2) or (3) in the block copolymer is not particularly limited, but is 0.001% by mass or more and 30% by mass when the block copolymer is 100% by mass. % Or less is preferable. A more preferable upper limit value is 15% by mass, further preferably 10% by mass, and particularly preferably 8% by mass. Moreover, a more preferable lower limit is 0.01% by mass, further preferably 0.1% by mass, and particularly preferably 1% by mass. By making the insertion amount 30% by mass or less, the rigidity of the resin molded product tends to be suppressed from being lowered. Moreover, it exists in the tendency which can suppress the fall of a creep characteristic by making insertion amount 0.001 mass% or more.

  The upper limit of the number average molecular weight of the block component in the block copolymer is preferably 10,000 in order not to lower the rigidity of the resin composition, more preferably 8,000, and still more preferably 5,000. It is. Although there is no lower limit, it is preferable that the lower limit is 100 from the viewpoint of maintaining stable slidability.

As compounds forming the block component in the block copolymer, _{specifically, 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; both-end hydroxyalkylated hydrogenated polybutadiene and the like.

  More preferably, the block copolymer is an ABA type block copolymer as its bonding form. Here, the ABA type block copolymer is a block copolymer having a block portion represented by the above formula (3). Specifically, a polyacetal segment A (hereinafter also referred to as “A”) and a hydrogenated polybutadiene segment B (hereinafter also referred to as “B”) in which both ends are hydroxyalkylated are represented by A-B-A. It is a block copolymer composed in order. Although the function manifestation mechanism is not clear, the creep property of the resin molded body of this embodiment tends to be further improved by using an ABA type block copolymer as the block copolymer.

The formula (1), the block component represented by formula (2) or Formula (3) may have the following unsaturated bond iodine value 20g-I ₂ / 100g. Specific examples of the unsaturated bond include a carbon-carbon double bond.

  As a polyacetal copolymer which has the said block component, the polyacetal block copolymer disclosed by the international publication 01/09213 is mentioned, for example, It can prepare by the method as described in the gazette.

  (A) Polyacetal homopolymer, polyacetal copolymer, polyacetal copolymer having a crosslinked structure, homopolymer-based block copolymer having a block portion, and copolymer-based block having a block component as the polyacetal resin constituting the resin molded body of the present embodiment Any of the copolymers can be used, and these can be used in combination. In addition, as the (A) polyacetal resin, for example, combinations having different molecular weights, combinations of polyacetal copolymers having different comonomer amounts, and the like can be used as appropriate.

  Among these, as described above, in the present embodiment, the (A) polyacetal resin is preferably a block copolymer. (A) Since the polyacetal resin is a block copolymer, it tends to be more possible to achieve both the fluidity as the resin molded body and the creep performance and to maintain the rigidity.

It is preferable that a block copolymer is 5 mass% or more and 95 mass% or less with respect to 100 mass% of all (A) polyacetal resins. The upper limit value is more preferably 90% by mass, further preferably 80% by mass, and particularly preferably 75% by mass. Further, the lower limit value is more preferably 10% by mass, further preferably 20% by mass, and particularly preferably 25% by mass. When the content is 5% by mass or more, the creep performance tends to be good. Moreover, it exists in the tendency for the rigidity of a resin molding to become favorable because it is 95 mass% or less. In addition, the ratio of said block copolymer in the resin molding of this embodiment can be measured by < ¹ > H-NMR, < ¹³ > C-NMR, etc.

<(B) Glass fiber>
The resin molding in this embodiment contains (B) 10 mass parts or more and 100 mass parts or less of (B) glass fiber with respect to 100 mass parts of (A) polyacetal resin. A preferable lower limit is 12 parts by mass, more preferably 15 parts by mass, still more preferably 20 parts by mass, and particularly preferably 25 parts by mass. Moreover, a preferable upper limit is 90 mass parts, More preferably, it is 80 mass parts, More preferably, it is 75 mass parts, Most preferably, it is 70 mass parts. When the amount of glass fiber is 10 parts by mass or more, creep resistance tends to be maintained, and when it is 100 parts by mass or less, high fluidity tends to be exhibited.

  As (B) glass fiber of this embodiment, if it is glass of a fiber shape, it can be used without a problem in particular. Specific examples include chopped strand glass fiber, milled glass fiber, and glass fiber roving. Among these, chopped strand glass fibers and milled glass fibers are preferable from the viewpoint of handleability, and chopped strand glass fibers are more preferable for increasing the creep property of the resin molded body. These (B) glass fibers may be used alone or in combination of two or more.

  The average fiber diameter of (B) glass fiber of this embodiment shall be in the range of 7 micrometers or more and 13 micrometers or less. The preferable lower limit of the average fiber diameter is 8 μm, and the preferable upper limit is 12 μm. By making the average fiber diameter 7 μm or more, deterioration of fluidity can be suppressed. Moreover, by making the average fiber diameter 13 μm or less, there is a tendency that deterioration of the creep property of the resin molded body can be suppressed, and an adverse effect such as scraping of the mold surface during molding tends to be prevented.

  Here, the average fiber diameter is easily obtained by incineration of the resin molded body at a temperature of about 650 ° C., removing the resin component, observing the obtained ash with a scanning electron microscope, and measuring the diameter. It can be measured. At this time, in order to eliminate the error, the number average fiber diameter is calculated by measuring the diameter of at least 100 glass fibers.

  In the present embodiment, even if two or more kinds of glass fibers having different glass fiber diameters are blended, the number average fiber diameter can be used without any problem as long as the number average fiber diameter is within the range of the present embodiment.

  The number average fiber length of (B) glass fiber of this embodiment shall be in the range of 150 micrometers or more and 350 micrometers or less. A preferable upper limit of the number average fiber length is 330 μm, more preferably 320 μm, and still more preferably 310 μm. Moreover, the preferable lower limit of a number average fiber length is 170 micrometers, More preferably, it is 180 micrometers, More preferably, it is 190 micrometers. By setting the number average fiber length to 150 μm or more, the creep property tends to be maintained. Moreover, it exists in the tendency which can suppress the deterioration of the fluidity | liquidity of a resin composition because a number average fiber length shall be 350 micrometers or less.

  The number average fiber length referred to here is obtained by measuring the resin molded body using an ash obtained by incineration at a temperature of 500 ° C. or lower for 5 hours or more and then slowly cooling. Heating at a low temperature for a long time and then slow cooling is preferable because glass fiber breakage due to thermal shock can be prevented. Using the dynamic powder image analysis device (for example, PITA-3 manufactured by Seishin Enterprise Co., Ltd.) for the obtained ash, soap water containing a small amount of neutral detergent is used as a developing solvent, and the length of the glass fiber Is measured by actually measuring at least 1000 or more.

  In this embodiment, the information corresponding to the glass fiber diameter at the time of measurement using the dynamic powder image analyzer is obtained as a circumscribed rectangular short diameter (corresponding to the glass fiber length). The information to be obtained is obtained as the circumscribed rectangular major axis, but in order to eliminate measurement errors due to the overlap of multiple glass fibers, etc., 2 μm or more from the glass fiber diameter confirmed with a scanning electron microscope, etc. The remote diameter information is deleted. Specifically, when the glass fiber diameter confirmed by a scanning electron microscope or the like is 10 μm, the information on particles having a circumscribed rectangular minor axis of 8 μm or less and the information on particles of 12 μm or more are deleted, and the number of remaining particles is 1000 Calculated with more information than books.

  The (B) glass fiber of this embodiment is 30% by mass or less, preferably 25% by mass or less of (B) glass fiber having a fiber length of 50 μm or less with respect to 100% by mass of (B) glass fiber. More preferably, it is 23 mass% or less, More preferably, it is 20 mass% or less. Since this value is preferably as small as possible, there is no particular lower limit value. However, even if it exists, the amount that does not affect the creep performance is 3% by mass. The amount of the glass fiber having a fiber length of 50 μm or less is also measured by using the dynamic powder image analyzer used in the above-described measurement of the number average fiber length. Specifically, the amount of fibers having a fiber length of 50 μm or less among 1000 or more particles is calculated from the information after performing the operation for removing the measurement error of the glass fiber diameter.

  In this embodiment, (B) the number average fiber length of the glass fibers is within a specific range, and the method of setting the amount of (B) glass fibers having a fiber length of 50 μm or less within the specific range is a polyacetal resin composition described later. For example, adjusting the method and conditions for melt kneading.

  It is preferable that (B) glass fiber which comprises the resin molding in this embodiment is processed with a coupling agent, a film formation agent, etc. as a sizing agent.

  Specific examples of the coupling agent include an organic silane compound, an organic titanate compound, an organic aluminate compound, and the like. However, the coupling agent is not limited to these, and all known ones can be used.

  Specific examples of the organic silane compound include vinyltriethoxysilane, vinyl-tris- (2-methoxyethoxy) silane, γ-methacryloxypropylmethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxy. Silane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-glycidoxypropylmethoxysilane, γ-mercaptopropyltrimethoxysilane Etc. Among these, vinyltriethoxysilane, vinyl-tris- (2-methoxyethoxy) silane, γ-methacryloxypropylmethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycid Xylpropylmethoxysilane is preferred. Among these, vinyltriethoxysilane and γ-glycidoxypropylmethoxysilane γ-aminopropyltriethoxysilane are preferable from the viewpoints of economy and thermal stability of the resin composition.

  Specific examples of the organic titanate compound include tetra-i-propyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetrastearyl titanate, triethanolamine titanate, titanium acetylacetonate, titanium lactate, and octylene bricol titanate. And isopropyl (N-aminoethylaminoethyl) titanate.

  Specific examples of the organic aluminate compound include acetoalkoxyaluminum diisopropylate.

  These coupling agents may be used alone or in combination of two or more.

  By using the glass fiber surface-treated with the coupling agent, the creep property of the resin molded product tends to be further improved, and the thermal stability of the resin molded product tends to be improved. .

  Specific examples of the film forming agent (sometimes referred to as a sizing agent) include a urethane resin, an epoxy resin, and a copolymer resin having at least one acid component. Among these, at least one kind is used. It is preferable that it is a film formation agent containing the copolymer resin which has the acid component of.

  The copolymer resin having at least one acid component includes a carboxylic acid-containing unsaturated vinyl monomer and an unsaturated vinyl monomer other than the carboxylic acid-containing unsaturated vinyl monomer as structural units. Examples include polymers, copolymers containing carboxylic acid anhydride-containing unsaturated vinyl monomers, and unsaturated vinyl monomers other than the carboxylic acid anhydride-containing unsaturated vinyl monomers as structural units. It is more preferable to use a copolymer containing as constituent units an acid-containing unsaturated vinyl monomer and an unsaturated vinyl monomer other than the carboxylic acid-containing unsaturated vinyl monomer.

  Specific examples of the above-mentioned carboxylic acid-containing unsaturated vinyl monomer include acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid, and the like. These may be used alone or in combination of two or more. It may be used. Specific examples of the carboxylic acid anhydride-containing unsaturated vinyl monomer include maleic acid and itaconic acid anhydride, which may be used alone or in combination.

  These film forming agents may be used alone or in combination of two or more.

  By arranging the film forming agent on the surface of the glass fiber, it tends to be able to increase the interfacial adhesion strength with the (A) polyacetal resin, and to tend to exhibit higher creep properties.

<(C) Polyolefin resin>
In the resin molding of this embodiment, it is preferable that (C) polyolefin resin is further included. By including the polyolefin resin, slidability can be imparted to the resin molded body. Moreover, it is more preferable to contain 0.01 mass part or more and 5 mass parts or less of (C) polyolefin resin with respect to 100 mass parts of (A) polyacetal resin. Furthermore, a preferable upper limit is 4 parts by mass, particularly preferably 3.5 parts by mass, and particularly preferably 3 parts by mass.

  The (C) polyolefin resin referred to in the present embodiment preferably has a weight average molecular weight in the range of 10,000 to 1,000,000. A more preferable upper limit of the weight average molecular weight is 800,000, more preferably 700,000, and particularly preferably 600,000. A more preferred lower limit is 50,000, even more preferably 100,000, and particularly preferably 120,000. The weight average molecular weight is measured by using a gel permeation chromatograph under conditions of 140 ° C. using o-dichlorobenzene as a solvent. If the weight average molecular weight is in the range of 10,000 to 1,000,000, the sliding property tends to be expressed.

前記式（４）中、Ｒ₂₁は水素原子又はメチル基であり、Ｒ₂₂は水素原子、炭素数１〜１０のアルキル基、カルボキシル基、２〜５個の炭素原子を含むアルキル化カルボキシ基、２〜５個の炭素原子を有するアシルオキシ基、又はビニル基を表す。 The (C) polyolefin resin that can be used in this embodiment includes a homopolymer of an olefin compound represented by the following general formula (4) and an olefin compound represented by the following general formula (4) as the main monomer. One or more polyolefin resins selected from the group consisting of copolymers and their modified products are preferred.

In the formula (4), R ₂₁ is a hydrogen atom or a methyl group, R ₂₂ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a carboxyl group, an alkylated carboxy group containing 2 to 5 carbon atoms, An acyloxy group having 2 to 5 carbon atoms or a vinyl group is represented.

  Other monomers can be appropriately selected from monomers that can be polymerized with the olefinic compound represented by the above general formula (4).

  Specific examples of the (C) polyolefin resin that can be used in the present embodiment include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, propylene-butene copolymer, polybutene, and water of polybutadiene. Examples thereof include an additive, an ethylene-acrylic acid ester copolymer, an ethylene-methacrylic acid ester copolymer, an ethylene-acrylic acid copolymer, and an ethylene-vinyl acetate copolymer. Among these, polyethylene, polypropylene, an ethylene-α-olefin copolymer, an ethylene-acrylic acid ester copolymer containing 5% by mass to 30% by mass of an acrylic acid ester unit; a polyolefin block and a hydrophilic polymer block Is a block copolymer having a structure in which it is alternately and alternately bonded through at least one bond selected from the group consisting of an ester bond, an amide bond, an ether bond, a urethane bond and an imide bond, and a group consisting of these modified products It is preferable from the viewpoint of improving slidability that it is at least one selected from more. Among these, polyethylene (high-pressure low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene), ethylene-propylene copolymer, ethylene-butene copolymer, and ethylene-octene copolymer are used in smaller amounts. It is more preferable because it can express the mobility.

  Specific examples of the polyolefin include polyethylene, polypropylene, and polybutadiene. Specific examples of the hydrophilic polymer include polyvinyl acetate, polymethyl methacrylate, and polylactic acid.

  In the present embodiment, a modified polyolefin resin (modified product) can be used without any problem as the (C) polyolefin resin. As the modified body, a graft copolymer obtained by grafting one or more other vinyl compounds different from the polymer forming the olefin resin; α, β-unsaturated carboxylic acid (acrylic acid, methacrylic acid, (Modified with maleic acid, fumaric acid, itaconic acid, citraconic acid, nadic acid, etc.) or its acid anhydride (with a peroxide if necessary); copolymerized olefinic compound and acid anhydride, etc. Is mentioned.

  These (C) polyolefin resins described above can be used alone or in a mixture.

  The (C) polyolefin resin that can be used in this embodiment has a melt flow rate (hereinafter also referred to as “MFR”) of 190 g / 10 min and 100 g / 10 min under a load condition of 190 ° C. and 2.16 kg. It is preferable to be within the range. By using the (C) polyolefin resin within this range, the slidability of the resin molded product tends to be improved.

  (C) The more preferable lower limit of MFR of the polyolefin resin is 0.02 g / 10 minutes, more preferably 0.05 g / 10 minutes, and particularly preferably 0.07 g / 10 minutes. Moreover, a more preferable upper limit is 50 g / 10 minutes, More preferably, it is 30 g / 10 minutes, Most preferably, it is 10 g / 10 minutes.

<Stabilizer component>
The polyacetal resin molded product of the present embodiment can contain various stabilizers that have been used in conventional polyacetal resin compositions as long as the object of the present invention is not impaired. Examples of the stabilizer include, but are not limited to, the following antioxidants, formaldehyde, formic acid scavengers, and the like. These may be used alone or in combination of two or more.

  The antioxidant is preferably a hindered phenol antioxidant from the viewpoint of improving the thermal stability of the resin molded body. It does not specifically limit as a hindered phenolic antioxidant, A well-known thing can be used suitably.

  Specific examples of formaldehyde and formic acid scavengers include compounds containing formaldehyde-reactive nitrogen, such as melamine and polyamide resins, and polymers thereof; alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylic acids Examples include salts. More specifically, calcium hydroxide, calcium carbonate, calcium phosphate, calcium silicate, calcium borate, fatty acid calcium salts (calcium stearate, calcium myristate, etc.) and the like can be mentioned. These fatty acids may be substituted with hydroxyl groups.

  The amount of each of the stabilizers described above is, for example, 0.1 parts by mass or more and 2 parts by mass or less of a hindered phenolic antioxidant as an antioxidant with respect to 100 parts by mass of the (A) polyacetal resin. The polymer containing formaldehyde-reactive nitrogen, which is a formic acid scavenger, is in the range of 0.1 to 3 parts by mass, and the alkaline earth metal fatty acid salt is in the range of 0.1 to 1 part by mass. preferable.

<Other ingredients>
The polyacetal resin molded body of this embodiment is a known filler other than glass fibers (glass flakes, glass beads, talc, wollast) conventionally used in polyacetal resin compositions, as long as the object of the present invention is not impaired. Knight, mica, calcium carbonate, etc.), conductivity imparting agents (carbon black, graphite, carbon nanotubes, etc.), colorants (titanium oxide, zinc oxide, iron oxide, aluminum oxide, organic dyes, etc.), sliding imparting agents (various) Various stabilizers such as ester compounds, organic acid metal salts, etc.), ultraviolet absorbers, light stabilizers, and lubricants can also be contained. These amounts are preferably 30% by mass or less with respect to 100% by mass of the resin molded body for fillers other than glass fibers, conductivity imparting agents, and colorants. The light stabilizer and the lubricant are preferably 5% by mass or less with respect to 100% by mass of the resin molded body. These may be used alone or in combination.

[Method for producing resin molded body]
The resin molding of this embodiment can be manufactured by a well-known method. Specifically, it can be produced by mixing, melt-kneading and molding the raw material components with a uniaxial or multi-axial kneading extruder, roll, Banbury mixer or the like as follows. Among these, a twin screw extruder equipped with a decompression device and a side feeder facility can be preferably used.

  A method for mixing and melt-kneading raw material components is not particularly limited, and methods known to those skilled in the art can be used. Specifically, component (A) and component (B) are mixed in advance with a super mixer, tumbler, V-shaped blender, etc., and melt melt-kneaded with a twin screw extruder, and component (A) is biaxial. The method etc. which add (B) component from the middle of an extruder, etc. are mentioned, supplying to an extruder main throat part and melt-kneading. Any of these can be used, but in order to make the component (B) constituting the resin molded body of this embodiment specific, the component (A) is supplied to the main throat portion of the twin-screw extruder and melt-kneaded. The method of adding the component (B) from the middle of the extruder is preferred. Moreover, the screw rotation speed and cylinder preset temperature of an extruder in this case can be suitably adjusted so that it may become the form of the above-mentioned glass fiber. In general, by increasing the screw rotation speed and lowering the cylinder set temperature, the number average fiber length of the component (B) becomes smaller, and the proportion of the fiber length of the component (B) of 50 μm or less tends to increase. . Since these optimum conditions vary depending on the size of the extruder, it is preferable to appropriately adjust them within a range adjustable by those skilled in the art. More preferably, the screw design of the extruder is adjusted in various ways within a range adjustable by those skilled in the art.

  It does not specifically limit about the shaping | molding method for obtaining the resin molding in this embodiment, A well-known shaping | molding method can be utilized. Specifically, extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, other material molding, gas assist injection molding, foam injection molding, low pressure molding, ultra-thin injection molding (ultra-high-speed injection) Molding), in-mold composite molding (insert molding, outsert molding), or any other molding method.

[Usage]
As a use of the resin molded body of the present embodiment, it can be suitably used for automobile mechanism parts that require long-term durability. Moreover, the resin molding containing (C) polyolefin resin can be used conveniently for the part which plays the role as a gear and a pulley which contacts another member.

  Besides these, it can be applied to known uses as a use of polyacetal resin. Specifically, mechanical parts represented by cams, sliders, levers, arms, clutches, felt clutches, idler gears, rollers, rollers, key stems, key tops, shutters, reels, shafts, joints, shafts, bearings, guides, etc. ; Outsert molded resin parts, insert molded resin parts, chassis, trays, side plates, automobile parts such as door locks, door handles, window regulators, speaker grills, etc .; door belt slip rings; Seat belt peripheral parts typified by press buttons; combination switch parts, switches, parts such as clips Gasoline tanks, fuel pump modules, valves, fuel tank parts typified by gasoline tank flanges, printers, and copies Off represented by machine Parts for video equipment such as digital video cameras and digital cameras; CD, DVD, Blu-ray Disc (registered trademark) and other optical disk drives; Music represented by navigation systems and mobile personal computers, It can be applied to parts for communication equipment typified by video or information equipment, mobile phones and facsimiles; parts for electrical equipment; parts for electronic equipment. In addition, as pens and pens for writing utensils, other mechanical parts; wash basins, drain outlets, drain plug opening / closing mechanism parts; cord stoppers for clothes, adjusters, buttons; nozzles for sprinkling, sprinkling hose connection joints; stairs Building supplies that support railings and floor materials; toys, fasteners, chains, conveyors, buckles, sporting goods, vending machines (opening / closing part locking mechanism, product discharge mechanism parts), furniture, musical instruments, housing equipment parts Can also be suitably used.

  According to the resin molded body of the embodiment, a resin molded body that achieves both high thin moldability and high creep characteristics can be obtained. Since this resin molding exhibits thin-wall moldability, for example, it is possible to provide a component suitable for reducing the weight of an automobile.

  Hereinafter, the present embodiment will be specifically described by way of examples and comparative examples. However, the present embodiment is not limited to these examples and comparative examples as long as the gist thereof is not exceeded. The processing conditions and evaluation items for the polyacetal resins and resin moldings of Examples and Comparative Examples are shown below.

(1) Extrusion Ratio of screw length L to screw diameter D (L / D) = 57 (14 barrels), side feeders are provided in the seventh and tenth barrels, and a vacuum vent is provided in the twelfth barrel. Using the same direction rotating twin screw extruder (TEM-48SS extruder manufactured by Toshiba Machine Co., Ltd.), cooling the cylinder with water or cooling the first barrel with water, the second to fifth barrels at 220 ° C., and the sixth to 14 barrels. Was set to 190 ° C. and extrusion was carried out with the composition described in each Example. At this time, the following four extrusion conditions were used. Which extrusion condition was used is described in the table of each example.

<Condition 1>
The screw used for extrusion is a kneading disk (hereinafter abbreviated as RKD) 2 having a flight screw (hereinafter abbreviated as FS) at the position of the 1st to 4th barrels and having feeding ability at the position of the 5th barrel. Two sheets of kneading discs (hereinafter abbreviated as NKD) without feeding capability and one kneading disc (hereinafter abbreviated as LKD) with feeding capability in the reverse direction are arranged in this order. FS is arranged at the position of the eighth barrel, RKD and NKD are arranged one by one at the position of the ninth barrel, SF is arranged at the positions of the tenth and eleventh barrels, and the position of the twelfth barrel is arranged. Two RKDs were arranged, and SF was arranged at the positions of the 13th to 14th barrels. Using this screw, glass fiber was supplied from the side feeder of the seventh barrel, and the extrusion was carried out with a screw rotation speed of 250 rpm and a total extrusion amount of 150 kg / h.

<Condition 2>
Except that the screw rotation speed was changed to 200 rpm, everything was carried out in the same manner as in Condition 1.
This condition is a condition that gives weaker shear than Condition 1.

<Condition 3>
All the conditions were the same as in Condition 2 except that glass fiber was supplied from the 10th barrel side feeder instead of the 7th barrel side feeder. Since the glass fiber addition position is shifted to the downstream side, the condition of the kneading zone received by the glass fiber is reduced, so that the glass fiber is less loaded.

<Condition 4>
As the screw to be used, except that the kneading disk at the position of the 12th barrel is changed to arrange one RKD, one NKD, and one LKD in this order, all are the same as the design of conditions 1 to 3, and the glass fiber is the condition 3 In the same manner as above, extrusion was performed from the side feeder of the 10th barrel, the screw rotation speed was 120 rpm, and the total extrusion amount was 120 kg / h. Although this condition cannot be directly compared with Conditions 1 to 3, it is a condition that keeps the screw rotational speed low while making a screw design that gives stronger shear.

(2) Molding (Creation of small tensile test piece shape molding by injection molding machine)
By using an injection molding machine (EC-75NII, manufactured by Toshiba Machine Co., Ltd.), the cylinder temperature is set to 205 ° C., and molding is performed under injection conditions of an injection time of 35 seconds and a cooling time of 15 seconds. A resin molded body in the form of a small tensile test piece conforming to the above was obtained. The mold temperature at this time was 80 ° C.

(3) MFR
The polyacetal resin and the MFR of the resin molded body were measured under the conditions of a cylinder temperature of 190 ° C. and a load of 2.16 kg in accordance with ISO1133.

(4) Average fiber diameter length The molded compact molded specimens were incinerated in an electric furnace set at 650 ° C. to remove the resin component. The ash obtained by cooling was observed with a scanning electron microscope or the like, and the diameter was measured. In this example, since glass fibers having a fiber diameter of 10 μm were used, almost all of them were 10 μm. When 200 were added and averaged, all were in the range of 9.4 μm to 10.5 μm.

(5) Number average fiber length The molded small tensile test piece shaped molded body was incinerated for 6 hours in an electric furnace set at 450 ° C. Thereafter, it was gradually cooled for 12 hours or more, and the obtained ash was used as a sample. Using a soap powder containing a small amount of a neutral detergent as a developing solvent, a sample was drawn with a dynamic powder image analyzer (PITA-3 manufactured by Seishin Enterprise Co., Ltd.). ) And the average fiber length was determined from the arithmetic average. At this time, in order to remove errors due to the overlap of the glass fibers, particles having a circumscribed rectangular minor axis of 8 μm or less and particles of 12 μm or more were excluded from the calculation target.

(6) Ratio of fiber length of 50 μm or less Using the data obtained by the above average fiber length measurement, the ratio of glass fibers having a fiber length of 50 μm or less was calculated.

(7) Spiral flow length (SFD)
Using an injection molding machine (EC-75NII, manufactured by Toshiba Machine Co., Ltd.), molding of a thin spiral shape having a width of 10 mm and a thickness of 1 mm was performed, and the flow lengths were compared. The longer the flow length, the better the thin-wall formability. The molding conditions were a cylinder temperature setting of 215 ° C., a mold temperature of 120 ° C., an injection speed of 270 mm / second (maximum capacity), an injection time of 35 seconds, a cooling time of 15 seconds, and the injection pressure was fixed at 150 MPa. For comparison, all examples and comparative examples were compared under the same conditions.

(8) Creep rupture time Using a molded compact molded specimen of a tensile test piece, a creep test was performed using a creep tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) under an 80 ° C environment under a load of 30 MPa. It implemented and compared by the time until it fractures. In the creep test, measurement was carried out with three pieces, and the average was taken as the creep rupture time.

(9) Amount of wear Using a ball-on-disk type reciprocating frictional wear tester (AFT-15MS type, manufactured by Toyo Seimitsu Co., Ltd.), the load was 19.6 N and the linear velocity was 30 mm in an environment of 23 ° C. and 50% humidity. / Sec, a reciprocating distance of 20 mm, and a reciprocating number of 10,000 times, the sliding test of the multi-purpose test piece shape molded body was performed. As the ball material, SUS304 balls (spheres with a diameter of 5 mm) were used. The amount of wear (wear depth, wear cross-sectional area) of the sample after the sliding test was measured using a confocal microscope (OPTELICS (registered trademark) H1200, manufactured by Lasertec Corporation). The wear cross-sectional area was the average of the values measured at n = 5, and was rounded to the nearest two significant figures. The lower the value, the better the wear characteristics.

The raw material components of the polyacetal resin compositions and molded bodies used in Examples and Comparative Examples will be described below. (A) The following grades manufactured by Asahi Kasei Chemicals Corporation were used as the polyacetal resin except for (A5).
(A1) Tenac (registered trademark) -C 3510 MFR = 3.0 g / 10 min Mn: about 100,000 (A2) Tenac (registered trademark) -C 4520 MFR = 9.0 g / 10 min Mn: about 70,000 (A3) ) Tenac (registered trademark) -C 5520 MFR = 15 g / 10 min Mn: about 50,000 (A4) Tenac (registered trademark) -C 7520 MFR = 45 g / 10 min Mn: about 25,000

(A5) The polyacetal block copolymer was prepared as follows. A twin-screw paddle type continuous polymerization machine with a jacket through which a heat medium can pass was adjusted to 80 ° C. 40 mol / hr of trioxane, 1,3-dioxolane as a cyclic formal 2 mol / hour, trioxane boron trifluoride di -n- butyl etherate dissolved in cyclohexane as a polymerization catalyst relative to 1 mol 5 × 10 ^{- The} amount of ⁵ moles, and the hydroxyl group-hydrogenated polybutadiene (number average molecular weight Mn = 2,330) represented by the following formula (5) as a chain transfer agent is 1 × 10 ⁻³ moles per mole of trioxane. Polymerization was conducted by continuously feeding the polymerizer in an amount.

  Next, the polymer discharged from the polymerization machine was put into a 1% aqueous solution of triethylamine to completely deactivate the polymerization catalyst, and then the polymer was filtered and washed to obtain a crude polyacetal block copolymer. .

  1 part by mass of an aqueous solution containing a quaternary ammonium compound is added to 100 parts by mass of the resulting crude polyacetal block copolymer, mixed uniformly, and fed 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 polyacetal block copolymer, and the unstable terminal portion of the polyacetal block copolymer is added at a preset temperature of the extruder of 200 ° C. and a residence time of 7 minutes in the extruder. Decomposition and removal were performed. At this time, the addition amount of the quaternary ammonium compound was 20 mass ppm in terms of the amount of nitrogen.

  To the polyacetal block copolymer in which the unstable terminal portion is decomposed, 0.3 parts by mass of triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] as an antioxidant Was extruded as a strand from the extruder die and pelletized while devolatilizing under a condition of a vacuum of 20 Torr with an extruder equipped with a vent.

  The polyacetal block copolymer thus obtained was used as (A5) polyacetal block copolymer. This block copolymer was an ABA type block copolymer, and the melt flow rate was 15 g / 10 min (ISO-1133 condition D). Mn (calculated from MFR) is about 50,000.

(B) The following glass fiber was used.
Owens Corning chopped strand glass fiber Product name: 03JAFT785 Fiber diameter: 10 μm Fiber length: 3 mm

(C) The following thing was used for polyolefin resin.
Asahi Kasei Chemicals Corporation Suntec (registered trademark) LD L1850A
MFR: 6.7 g / 10 min, density: 918 kg / m3 (conforms to JIS K7112)

[Examples 1-6, Comparative Examples 1-3]
Extrusion was carried out under the respective extrusion conditions so that each component had the ratio described in Table 1, and various performance evaluations were performed. The results are shown in Table 1.

  The comparison between Examples 1 to 3 and Comparative Example 1 shows the difference due to the change in MFR (molecular weight) of the polyacetal used as the resin composition. It can be seen that Comparative Example 1 having a low MFR of polyacetal (high molecular weight) has a low SFD value and inferior thin-wall moldability. It can be seen that by increasing the MFR of the polyacetal in Examples 1 to 3 (lowering the molecular weight), the ratio of the fiber length of the glass fiber to 50 μm or less decreases, and the creep property is dramatically improved. Despite the lower molecular weight of the base resin, the creep property is improved.

  In the comparison between Examples 3 to 5 and Comparative Example 2, the difference due to the processing method of the composition having the same composition is shown. Although the composition is the same, the ratio of the glass fiber having a fiber length of 50 μm or less is greatly changed by changing the extrusion method. For example, in Comparative Example 2, it is understood that the creep performance is drastically decreased. The comparison between Examples 1, 2, and 6 and Comparative Example 3 is the same, and it can be seen that, despite the same composition, the creep performance changes abruptly due to the difference in the extrusion method.

[Examples 3 and 7 to 9, Comparative Examples 4 and 5]
Extrusion was carried out under the respective extrusion conditions so that each component had the ratio described in Table 2, and various performance evaluations were performed. Example 3 was reprinted to aid understanding. The results are shown in Table 2.

  All the contrasts of Examples 3 and 7 to 9 and Comparative Example 4 represent differences when the glass fiber amount is changed. It can be seen that in condition 4, if the glass fiber is within the range of 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the polyacetal resin, all of the conditions 4 give good creep properties. However, when the amount exceeds 100 parts by mass, defibration failure occurred. Therefore, it was not evaluated because correct comparison could not be performed. In order to solve this problem, in Comparative Example 5, an attempt was made to change to Condition 1 which is considered to give higher shear, but this was stopped because the resin temperature increased and the polyacetal resin was thermally decomposed.

[Example 2, 10-13]
Extrusion was carried out under the respective extrusion conditions so that each component had the ratio described in Table 3, and various performance evaluations were performed. Example 2 was reprinted to aid understanding. The results are shown in Table 3.

  The comparison between Examples 2, 10, and 11 represents the difference due to the use of the block copolymer type as the polyacetal resin. It can be seen that the creep property is remarkably increased by using the block copolymer type as the polyacetal resin. In addition, although the polyacetals of A3 and A5 have almost the same molecular weight and MFR, the MFR of the obtained resin molding is higher when the block copolymer type of A5 is used, and it is understood that the thin-wall moldability is excellent. . Further, Example 11 was extruded under condition 1, which is a harsher condition, but it can be seen that a relatively high creep property is maintained despite a high ratio of fiber length of 50 μm or less.

  Moreover, the comparison of Example 10, 12, and 13 represents the difference in the effect which added polyethylene as an additional component. It can be seen that the amount of wear is drastically reduced by the addition of the polyethylene component, and the creep property is not adversely affected.

  The resin molded body of the present invention has industrial applicability in various fields where polyacetal resins have been suitably used, particularly in the field of automobile mechanism parts that require long-term durability.

Claims (5)

(A) polyacetal resin and (B) glass fiber 10 parts by mass to 100 parts by mass with respect to 100 parts by mass of (A) polyacetal resin,
(A) The number average molecular weight of the polyacetal resin is 20,000 or more and 70,000 or less,
(B) The average fiber diameter of the glass fiber is 7 μm or more and 13 μm or less, the number average fiber length is 150 μm or more and 350 μm or less,
(B) Glass fiber 100 mass%, fiber length 50 μm or less (B) glass fiber is 30 mass% or less,
A resin molded article having a melt flow rate (ISO 1133 compliant, temperature 190 ° C., load 2.16 kg) of 10 g / 10 min or more and 30 g / 10 min or less. (A) polyacetal resin melt flow rate (ISO 1133-compliant, temperature 190 ° C., load of 2.16 kg) is less than or equal 10 g / 10 min or more 100 g / 10 min, the resin molded body according to claim 1. (A) The resin molding of Claim 1 or 2 whose polyacetal resin is a block copolymer. The resin molding as described in any one of Claims 1-3 which further contains 0.01 mass part or more and 5 mass parts or less of (C) polyolefin resin with respect to 100 mass parts of (A) polyacetal resin. (C) Polyolefin resin is polyethylene, polypropylene, ethylene-α-olefin copolymer, ethylene-acrylic acid ester copolymer containing 5% by mass to 30% by mass of acrylic acid ester unit, polyolefin block and hydrophilic polymer A block copolymer having a structure in which the block is repeatedly bonded alternately through at least one bond selected from the group consisting of an ester bond, an amide bond, an ether bond, a urethane bond and an imide bond, and modified products thereof, The resin molding of Claim 4 which is at least 1 sort (s) chosen from the group which consists of.