Polyacetal resin composition

Abstract

To provide a polyacetal resin composition having excellent mechanical properties and hot water resistance.SOLUTION: There is provided a polyacetal resin composition which comprises (A) 100 pts.mass of a polyacetal resin, (B) 1 pt.mass or more and 100 pts.mass or less of a glass fiber and (C) 0.002 pt.mass or more and 10 pts.mass or less of a triazine derivative having a nitrogen-containing functional group. The glass fiber (B) is surface treated with a surface treatment agent containing at least one selected from a blocked isocyanate compound, an aminosilane coupling agent, an epoxy resin and a polyurethane resin and a boric acid compound.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polyacetal resin composition. [Background technology]

[0002] Polyacetal resins have excellent mechanical properties, fatigue resistance, friction and abrasion resistance, chemical resistance, and moldability, and are therefore widely used in the fields of automobile parts, electrical and electronic equipment parts, other precision machine parts, building materials and piping materials, lifestyle and cosmetic parts, medical parts, etc. With the expansion and diversification of such uses, the demands for their quality are becoming higher. For example, it is known to compound glass-based inorganic fillers as reinforcing agents in order to improve the mechanical properties of polyacetal resins, such as their strength and rigidity.

[0003] However, since the polyacetal resin has poor activity and the glass-based inorganic filler also has poor activity, simply blending the polyacetal resin with the glass-based inorganic filler and melt-kneading the mixture often results in insufficient adhesion between the two, and the desired improvement in mechanical properties cannot be obtained. Therefore, various methods have been proposed for improving the adhesion between the polyacetal resin and the glass-based inorganic filler to improve the mechanical properties.

[0004] For example, Patent Document 1 considers the addition of a glass-based inorganic filler and a boric acid compound to a polyacetal resin, and Patent Document 2 considers the use of glass fibers that have been surface-treated with a blocked isocyanate and a specific silane compound. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-151298 [Patent Document 2] Japanese Patent Application Publication No. 3-079631 Summary of the Invention [Problem to be solved by the invention]

[0006] As a result of the above-mentioned studies, it was possible to improve the mechanical properties of polyacetal resins, but further improvement was required with respect to hot water resistance.

[0007] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a polyacetal resin composition having excellent mechanical properties and excellent hot water resistance. [Means for solving the problem]

[0008] Means for Solving the Problems The present inventors have conducted extensive research aimed at solving the above problems and have found that a polyacetal resin composition having excellent mechanical properties and hot water resistance can be obtained by using glass fibers that have been surface-treated with a surface treatment agent containing a boric acid compound, thereby completing the present invention.

[0009] [1] A polyacetal resin composition comprising: (A) 100 parts by mass of a polyacetal resin; (B) at least 1 part by mass and at most 100 parts by mass of a glass fiber; and (C) at least 0.002 parts by mass and at most 10 parts by mass of a triazine derivative having a nitrogen-containing functional group, the (B) glass fiber being surface-treated with a surface treatment agent containing at least one selected from the group consisting of a blocked isocyanate compound, an aminosilane coupling agent, an epoxy resin, and a polyurethane resin, and a boric acid compound. [2] The polyacetal resin composition according to [1], wherein the (C) triazine derivative having a nitrogen-containing functional group is melamine. [3] The polyacetal resin composition according to [1], containing (D) 0.001 part by mass or more and 1.0 part by mass or less of a boric acid compound. [4] The polyacetal resin composition according to [3], wherein the boric acid compound is orthoboric acid. [5] (E) The polyacetal resin composition according to [1], containing 0.01 parts by mass or more and 15 parts by mass or less of carbon black. [6] The polyacetal resin composition according to [5], wherein the carbon black is acetylene black. [7] (F) The polyacetal resin composition according to [1], containing 0.01 parts by mass or more and 5 parts by mass or less of a polyolefin wax. [8] The polyacetal resin composition according to [7], wherein the polyolefin wax is a polyethylene wax. Effect of the Invention

[0010] According to the present invention, it is possible to provide a polyacetal resin composition having excellent mechanical properties and excellent hot water resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Specific embodiments of the present invention will be described in detail below. Note that the present invention is not limited to the following embodiments, and appropriate modifications can be made without departing from the spirit and scope of the present invention.

[0012] [Polyacetal resin composition] A polyacetal resin composition according to one embodiment of the present invention contains (A) 100 parts by mass of a polyacetal resin, (B) 1 part by mass or more and 100 parts by mass or less of a glass fiber, and (C) 0.002 parts by mass or more and 10 parts by mass or less of a triazine derivative having a nitrogen-containing functional group.

[0013] <(A) Polyacetal resin> The polyacetal resin according to one embodiment of the present invention is preferably a homopolymer or a copolymer.

[0014] <Homopolymer> A homopolymer is a polymer composed of a single monomer. In addition, a homopolymer in polyacetal polymers is a polymer that has an oxymethylene group (-OCH 2 -) in the main chain.

[0015] The homopolymer can be obtained by anionic polymerization of formaldehyde in the presence of a polymerization catalyst. The terminals of the crude polyoxymethylene obtained in the polymerization step must be stabilized using an etherification agent, esterification agent, or the like.

[0016] In one embodiment of the present invention, the homopolymer may be a homopolymer polymerized by the above-mentioned method, or a commercially available product may be used. Examples of the commercially available product include Delrin (manufactured by DuPont (USA), "Delrin" is a registered trademark of the company) and Tenac (manufactured by Asahi Kasei Corporation, "Tenac" is a registered trademark of the company).

[0017] <Copolymer> A copolymer is a copolymer made up of two or more monomers. In addition, copolymers in polyacetal polymers are copolymers that have an oxymethylene group (-OCH 2 -) in the main chain and also contains other groups such as oxyalkylene groups having two or more carbon atoms in the molecule.

[0018] The copolymer can be obtained by copolymerizing trioxane with a comonomer copolymerizable with trioxane in the presence of a polymerization catalyst.

[0019] (Trioxane) Trioxane is a cyclic trimer of formaldehyde. It is generally obtained by reacting an aqueous solution of formaldehyde in the presence of an acid catalyst, and is purified by a method such as distillation.

[0020] (Comonomer) The comonomer is preferably selected from the group consisting of cyclic ethers and cyclic formals having at least one carbon-carbon bond.

[0021] Examples of the comonomer include 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, epichlorohydrin, etc. Among these, 1,3-dioxolane is preferred from the viewpoint of polymerization stability.

[0022] Also usable as the comonomer are compounds having two polymerizable cyclic ether groups or cyclic formal groups, such as diglycidyl ether of alkylene glycol, such as butanediol diglycidyl ether, diformal, and compounds having three or more polymerizable cyclic ether groups or cyclic formal groups, such as glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, etc. By using these comonomers, a polyacetal resin having a branched structure or a crosslinked structure can be obtained.

[0023] The copolymer can be polymerized by a known method using a known polymerization apparatus such as a batch type or continuous type.

[0024] The copolymer may be a copolymer polymerized by the above-mentioned method, or a commercially available product may be used. Examples of commercially available products include Duracon (manufactured by Polyplastics Co., Ltd., "Duracon" is a registered trademark of the company).

[0025] The polyacetal resin according to one embodiment of the present invention is not particularly limited with respect to its molecular weight, and is preferably melt moldable (for example, the melt flow rate (MFR) measured at 190°C under a load of 2160 g in accordance with ISO 1133 is 1.0 g / 10 min to 100 g / 10 min). The MFR can be measured, for example, using a Melt Indexer L220 (manufactured by Tateyama Kagaku High-Technologies Corporation).

[0026] <(B) Glass fiber> The glass fiber according to one embodiment of the present invention is surface-treated with a surface treatment agent containing at least one selected from a blocked isocyanate compound, an aminosilane coupling agent, an epoxy resin, and a polyurethane resin, and a boric acid compound.

[0027] Glass fiber is a fibrous material whose cross section when cut perpendicular to the length is circular or polygonal. Examples of glass fiber include A-glass, C-glass, E-glass, R-glass, D-glass, M-glass, and S-glass.

[0028] The form of the glass fiber may be any of glass rovings obtained by continuously winding a single fiber or a plurality of single fibers twisted together, chopped strands cut to a length of 1 to 10 mm (glass fibers having a number average fiber length of 1 to 10 mm), milled fibers (glass fibers having a number average fiber length of 10 to 500 μm) pulverized to a length of 10 to 500 μm, etc. These may be used alone or in combination of two or more kinds.

[0029] The single fiber diameter of the glass fiber is not particularly limited, but is preferably 8 μm or more and 20 μm or less. When the single fiber diameter of the glass fiber is within this range, a polyacetal resin composition having excellent mechanical properties and excellent hot water resistance can be obtained. The "single fiber diameter" refers to the average diameter of 25 filament cross sections measured in accordance with JIS R 3420.

[0030] <Surface treatment agent> As described above, the surface treatment agent for treating the surface of the glass fiber contains at least one selected from the group consisting of a blocked isocyanate compound, an aminosilane coupling agent, an epoxy resin, and a polyurethane resin, and a boric acid compound.

[0031] (Blocked isocyanate compound) A blocked isocyanate compound is a compound obtained by reacting a blocking agent with the isocyanate group of an isocyanate compound. The blocked isocyanate compound is stable at room temperature, but when heated under certain conditions, the blocking agent is cleaved to generate an isocyanate group.

[0032] Examples of the isocyanate compound that is the raw material of the blocked isocyanate compound include aliphatic, alicyclic (hereinafter also referred to as "alicyclic") and aromatic isocyanate compounds. Among these, from the viewpoint of compatibility and suitability with polyacetal resin, aliphatic or alicyclic isocyanate compounds are preferred, and aliphatic or alicyclic diisocyanate compounds, or polyisocyanates obtained by polymerizing the diisocyanates, are more preferred.

[0033] The aliphatic diisocyanate preferably has a carbon number of 4 or more and 30 or less, and more preferably has a carbon number of 5 or more and 10 or less. Examples of the aliphatic diisocyanate include 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexanediyl diisocyanate, lysine diisocyanate, and the like.

[0034] The alicyclic diisocyanate preferably has a carbon number of 8 to 18, and more preferably has a carbon number of 10 to 15. Examples of the alicyclic diisocyanate include isophorone diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, and the like.

[0035] Examples of aromatic diisocyanates include xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and the like.

[0036] The polyisocyanate is preferably a compound having at least two isocyanate groups per molecule. Examples of the polyisocyanate include aromatic diisocyanates such as tolylene diisocyanate or diphenylmethane diisocyanate, aralkyl diisocyanates such as m-xylylene diisocyanate, α,α,α',α'-tetramethyl-m-xylylene diisocyanate, prepolymers having an isocyanate group obtained by reacting aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and the like with polyhydric alcohols, prepolymers having an isocyanurate ring obtained by cyclizing and trimerizing diisocyanates, and polyisocyanates having a biuret structure obtained by reacting diisocyanates with water.

[0037] Among these, from the viewpoints of the impact resistance, durability, and industrial availability of the resulting composition, hexamethylene diisocyanate or a polymer of hexamethylene diisocyanate (for example, a dimer, (cyclic) trimer, pentamer, heptamer, nonamer, eleven-mer, or a mixture thereof, etc.) is preferred. These may be used alone or in combination of two or more kinds.

[0038] As the blocked isocyanate compound, any of the above-mentioned isocyanate compounds in which the reactive group is blocked with a known blocking agent by a known method can be used without any particular limitation.

[0039] Examples of blocking agents include oxime-based blocking agents such as methyl ethyl ketoxime, acetoxime, cyclohexanone oxime, acetophenone oxime, and benzophenone oxime, phenol-based blocking agents such as phenol, cresol, propylphenol, butylphenol, and xylenol, alcohol-based blocking agents such as methanol, ethanol, butanol, 2-ethylhexanol, cyclohexanol, and ethylene glycol monoethyl ether, lactam-based blocking agents such as ε-caprolactam, diketone-based blocking agents such as diethyl malonate and acetoacetate, mercaptan-based blocking agents such as thiophenol, urea-based blocking agents such as thiourea, imidazole-based blocking agents, carbamic acid-based blocking agents, and bisulfites. Among these, lactam-based blocking agents, oxime-based blocking agents, and diketone-based blocking agents are preferred.

[0040] (Aminosilane coupling agent) An aminosilane coupling agent is a compound that contains, in one molecule, a silicon atom to which an alkoxy group is bonded and a functional group containing a nitrogen atom.

[0041] Examples of the aminosilane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N,N'-bis[3-(trimethoxysilyl)propyl]ethylenediamine, N,N'-bis[3-(triethoxysilyl)propyl]ethylenediamine, N,N'-bis[3-(methyldimethoxysilyl)propyl]ethylenediamine, N,N'-bis[3-(trimethoxysilyl)propyl]hexamethylenediamine, N,N'-bis[3-(triethoxysilyl)propyl]hexamethylenediamine, and the like.

[0042] Among these, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, or N-phenyl-3-aminopropyltrimethoxysilane is preferred, and 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane is more preferred.The aminosilane coupling agent may be used alone or in combination of two or more kinds.

[0043] By using an aminosilane coupling agent in combination with the above-mentioned blocked isocyanate compound, the adhesion between the polyacetal resin and the glass fiber can be improved.

[0044] (Epoxy resin) Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, novolac type epoxy resins such as phenol novolac type or cresol novolac type epoxy resins, aliphatic epoxy resins, hydrogenated types or ether modified products thereof, phenoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, cyclic aliphatic epoxy resins, urethane modified epoxy resins, etc. The epoxy resins may be used alone or in combination of two or more types.

[0045] Among these, bisphenol A type epoxy resins and phenol novolac type epoxy resins are preferred from the viewpoints of bundling of glass fibers and hot water resistance.

[0046] (Polyurethane resin) From the viewpoint of bundling property, the polyurethane resin is preferably a resin obtained from a polyisocyanate component mainly composed of xylylene diisocyanate and a polyol component mainly composed of polyester polyol. Here, examples of xylylene diisocyanate include o-xylylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, and mixtures thereof. Among these, m-xylylene diisocyanate is preferred.

[0047] Examples of polyester polyols include condensation-based polyester polyols obtained by dehydration condensation of polyhydric alcohols and polycarboxylic acids, lactone-based polyester polyols obtained by ring-opening polymerization of lactones based on polyhydric alcohols, ester-modified polyols in which the ends of polyether polyols are ester-modified with lactones, and copolymerized polyester polyols thereof.

[0048] Examples of polyhydric alcohols used in the condensation polyester polyols include ethylene glycol, propylene glycol, 1,3-propanediol, butylene glycol, 1,4-butanediol, 1,5-pentanediol, hexylene glycol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, and the like.

[0049] Examples of polyvalent carboxylic acids used in the condensation polyester polyols include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and trimellitic acid.

[0050] Examples of lactone-based polyester polyols include poly(ε-caprolactone) polyols.

[0051] The weight average molecular weight (Mw) of the polyester polyol is preferably from 500 to 4000. Here, the weight average molecular weight is a value measured by gel permeation chromatography (GPC) and converted using a calibration curve prepared using standard polystyrene.

[0052] The polyurethane resin can be produced by heating xylylene diisocyanate and polyester polyol at 30°C to 130°C without a solvent or in the presence of a small amount of an organic solvent. When carrying out the heating reaction, the above-mentioned polyhydric alcohol may be appropriately added as a chain extender. The organic solvent is not particularly limited, but is preferably one that does not react with isocyanate and is miscible with water. Examples of the organic solvent include acetone, methyl ethyl ketone, tetrahydrofuran, dimethylformamide, etc.

[0053] The polyurethane resin is preferably used by dissolving in an organic solvent or dispersing in water together with the above-mentioned blocked isocyanate compound and aminosilane coupling agent. Examples of the method for producing the aqueous emulsion containing the polyurethane resin include a self-emulsification method and a method using an emulsifier. These methods may be combined.

[0054] (boric acid compounds) Examples of the boric acid compound include orthoboric acid, metaboric acid, tetraboric acid, and dehydrated orthoboric acid. Among these, orthoboric acid is preferred. By including a boric acid compound, the strength and hot water resistance of the polyacetal resin composition can be significantly improved.

[0055] The amount of each of the components constituting the surface treatment agent is preferably 0.1 to 10 parts by mass, 0.001 to 0.3 parts by mass, 0.05 to 1 parts by mass, 0.05 to 1 parts by mass, 0.01 to 1 parts by mass for the blocked isocyanate compound, the aminosilane coupling agent, the epoxy resin, the polyurethane resin, and the boric acid compound, respectively, based on 100 parts by mass of the glass fiber before the surface treatment, and more preferably 0.3 to 3 parts by mass, 0.01 to 0.2 parts by mass, 0.05 to 0.8 parts by mass, 0.05 to 0.3 parts by mass, and 0.01 to 0.5 parts by mass. The mass ratio of the blocked isocyanate compound, the aminosilane coupling agent, the epoxy resin, the polyurethane resin, and the boric acid compound is preferably 94 to 45: 1 to 15: 5 to 40: 5 to 40: 1 to 40, and more preferably 92 to 50: 2 to 12: 6 to 38: 6 to 38: 2 to 35.

[0056] The content of the surface-treated glass fiber is preferably 1 part by mass or more and 100 parts by mass or less, more preferably 5 parts by mass or more and 75 parts by mass or less, and particularly preferably 10 parts by mass or more and 60 parts by mass or less, relative to 100 parts by mass of the polyacetal resin. When the content of the surface-treated glass fiber is within the above range, the mechanical strength and hot water resistance of the polyacetal resin composition can be increased.

[0057] Whether or not the surface-treated glass fiber has been surface-treated with a surface treatment agent containing at least one selected from a blocked isocyanate compound, an aminosilane coupling agent, an epoxy resin, and a polyurethane resin, and a boric acid compound, can be identified by extracting the glass fiber from the polyacetal resin composition with a solvent and performing a component analysis using, for example, pyrolysis GC / MS.

[0058] <(C) Triazine derivative having a nitrogen-containing functional group> Examples of triazine derivatives having a nitrogen-containing functional group (hereinafter also referred to as "triazine derivatives") include methylol melamines such as melamine, N-methylol melamine, N,N'-dimethylol melamine, N,N',N''-trimethylol melamine, N,N,N',N''-tetramethylol melamine, and mixtures thereof, alkoxymethyl derivatives of methylol melamine (for example, alkoxymethyl melamines described in JP-A-55-157645 and melamine prepolymers described in JP-B-7-116346), guanamine compounds such as benzoguanamine, acetoguanamine, and 2,4-diamino-6-butyl-sym-triazine, N-butyl melamine, N-phenyl melamine, N,N-diphenyl melamine, N,N-diallyl melamine, N,N',N-triphenyl melamine, ameline, and 2,4-diamino-6-benzyloxy-sym-triazine. , 2,4-diamino-6-butoxy-sym-triazine, 2,4-diamino-6-cyclohexyl-sym-triazine, 2,4-diamino-6-chloro-sym-triazine, 2,4-diamino-6-mercapto-sym-triazine, 2,4-dioxy-6-amino-sym-triazine, 2-oxy-4,6-diamino-sym-triazine, 1,1-bis(3,5-diamino-2,4,6-triazinyl)methane , 1,2-bis(3,5-diamino-2,4,6-triazinyl)ethane [also known as succinoguanamine], 1,3-bis(3,5-diamino-2,4,6-triazinyl)propane, 1,4-bis(3,5-diamino-2,4,6-triazinyl)butane, methyleneated melamine, ethylene dimelamine, triguanamine, melamine cyanurate, ethylene dimelamine cyanurate, triguanamine cyanurate, etc. The triazine derivatives may be used alone or in combination of two or more.

[0059] Among these, guanamine compounds such as benzoguanamine and acetoguanamine, methylolmelamine, alkoxymethyl derivatives of methylolmelamine, and melamine are preferred, with melamine being more preferred.

[0060] The content of the triazine derivative is preferably from 0.002 to 10 parts by mass, more preferably from 0.01 to 2 parts by mass, and particularly preferably from 0.03 to 1 part by mass, relative to 100 parts by mass of the polyacetal resin.

[0061] When the content of the triazine derivative is 0.002 parts by mass or more, the mechanical properties of the polyacetal resin composition can be improved, and when it is 10 parts by mass or less, bleeding from the polyacetal resin composition can be reduced.

[0062] The polyacetal resin composition according to one embodiment of the present invention contains surface-treated glass fiber (B) and triazine derivative (C), and thus has excellent mechanical properties and hot water resistance. The present inventors speculate that this effect is due to a synergistic effect caused by the interaction of compounds contained in a specific surface treatment agent within a certain range of amounts.

[0063] <(D) Boric acid compounds> The polyacetal resin composition according to one embodiment of the present invention may contain a boric acid compound. The boric acid compound may be the same as the boric acid compound contained in the above-mentioned surface treatment agent. Among the above-mentioned boric acid compounds, orthoboric acid is preferred.

[0064] The content of the boric acid compound is preferably 0 to 3 parts by mass, more preferably 0.01 to 2 parts by mass, and particularly preferably 0.01 to 1 part by mass, relative to 100 parts by mass of the polyacetal resin. By including the boric acid compound in the above range, a polyacetal resin composition having excellent mechanical properties and excellent hot water resistance can be obtained.

[0065] <(E) Carbon Black> The polyacetal resin composition according to one embodiment of the present invention may contain carbon black. The carbon black is not particularly limited as long as it is a generally available carbon black that is used for resin coloring.

[0066] Examples of carbon black include furnace black, acetylene black, ketjen black, channel black, lamp black, thermal black, etc. Among these, acetylene black is preferred.

[0067] The content of carbon black is preferably 0 part by mass or more and 1 part by mass or less, and more preferably 0.05 part by mass or more and 1 part by mass or less, relative to 100 parts by mass of the polyacetal resin.

[0068] <(F) Polyolefin wax> The polyacetal resin composition according to one embodiment of the present invention may contain a polyolefin wax. The polyolefin wax is not particularly limited as long as it is a generally available wax.

[0069] Examples of polyolefin waxes include polyolefin waxes such as polyethylene wax, polypropylene wax, polybutene wax, etc., paraffin wax, microcrystalline wax, sazol wax, etc., long-chain hydrocarbon waxes and derivatives thereof, polyester waxes and derivatives thereof, polyamide waxes and derivatives thereof, etc. Among these, polyethylene wax is preferred.

[0070] The content of the polyolefin wax is preferably 0 to 1 part by mass, more preferably 0.05 to 0.3 parts by mass, relative to 100 parts by mass of the polyacetal resin. By including the polyolefin wax in this range, it is possible to suppress the deterioration of physical properties that may occur when carbon black is added to the polyacetal resin composition to obtain a black molded product.

[0071] <Other additives> The polyacetal resin composition according to one embodiment of the present invention may contain glass fibers that have been surface-treated with a known coupling agent other than an aminosilane coupling agent. Examples of the coupling agent include silane-based, titanate-based, aluminum-based, chromium-based, zirconium-based, and borane-based coupling agents.

[0072] The polyacetal resin composition according to one embodiment of the present invention may contain various known stabilizers and additives.

[0073] Examples of the stabilizer include hindered phenol compounds, hindered amine compounds, nitrogen-containing basic compounds, oxides, hydroxides, inorganic salts, carboxylates of alkali or alkaline earth metals, etc. Examples of the additives include colorants such as dyes and pigments, fluorescent brighteners, lubricants, nucleating agents, release agents, antistatic agents, surfactants, etc.

[0074] In addition, known inorganic, organic, and metallic fillers in the form of fibers, plates, powders, etc. other than glass fibers may be included to the extent that the object of the present invention is not impaired. Examples of fillers include talc, mica, wollastonite, carbon fibers, glass beads, etc.

[0075] [Molded products] The molded article according to one embodiment of the present invention is composed of a polyacetal resin composition containing (A) a polyacetal resin, (B) a surface-treated glass fiber, and (C) a triazine derivative having a nitrogen-containing functional group. The polyacetal resin composition may also contain at least one of (D) a boric acid compound, (E) carbon black, and (F) a polyolefin wax. The molded article includes not only parts made of the polyacetal resin composition, but also polyacetal resin processed into a powder, pellet, or other form.

[0076] By using a polyacetal resin composition containing the above-mentioned components, a polyacetal resin composition having excellent mechanical properties and excellent hot water resistance can be obtained. EXAMPLES

[0077] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

[0078] <Method for producing polyacetal resin composition> The polyacetal resin compositions shown in Tables 1 to 4 were produced as described below.

[0079] In a vessel containing 100 parts by mass of polyacetal resin, glass fiber, triazine derivative, boric acid compound, carbon black, and polyolefin wax were blended in the amounts shown in Tables 1 to 4, and the mixture was melt-kneaded and extruded using a vented twin-screw extruder under conditions of a cylinder temperature of 220°C and a vacuum degree of 5 mmHg at the vent to obtain the polyacetal resin compositions shown in Tables 1 to 4. At this time, the glass fiber was added by side feed. The units of values ​​in Tables 1 to 4 are parts by mass.

[0080] The components of the polyacetal resin compositions shown in Tables 1 to 4 are as follows.

[0081] <(A) Polyacetal resin> (A-1) Polyacetal resin (polyacetal copolymer obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane (MFR: 45 g / 10 min) (A-2) Polyacetal resin (polyacetal copolymer obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane (MFR: 9 g / 10 min)

[0082] The MFR was measured at 190° C. under a load of 2160 g in accordance with ISO 1133. The MFR was measured using a Melt Indexer L220 (manufactured by Tateyama Scientific High-Technologies Corporation).

[0083] <(B) Glass fiber> Glass fibers (B-1) to (B-8) are chopped strands with a single fiber diameter of 10 μm, and are surface-treated with the following surface treatment agents. The types and contents of each component of the surface treatment agents are shown below. The contents of each component of the surface treatment agents are defined based on 100 parts by mass of untreated glass fibers.

[0084] (B-1) Blocked isocyanate: hexamethylene isocyanate blocked with methyl ethyl ketoxime (1.0 part by mass) Aminosilane coupling agent: 3-aminopropyltriethoxysilane (0.1 parts by mass) Polyurethane resin (0.2 parts by weight) Epoxy resin: Bisphenol A type epoxy resin (0.2 parts by mass) Boric acid compound: orthoboric acid (0.05 parts by mass) (B-2) Blocked isocyanate: hexamethylene diisocyanate trimer blocked with methyl ethyl ketoxime (0.8 parts by weight) Aminosilane coupling agent: 3-aminopropyltriethoxysilane (0.1 parts by mass) Epoxy resin: Bisphenol A type epoxy resin (0.1 parts by mass) Boric acid compound: orthoboric acid (0.1 parts by mass) (B-3) Blocked isocyanate: hexamethylene diisocyanate trimer blocked with methyl ethyl ketoxime (0.8 parts by weight) Aminosilane coupling agent: aminopropyltriethoxysilane (0.1 parts by mass) Epoxy resin: Bisphenol A type epoxy resin (0.1 parts by mass) Boric acid compound: orthoboric acid (0.15 parts by mass) (B-4) Blocked isocyanate: hexamethylene diisocyanate trimer blocked with methyl ethyl ketoxime (1.2 parts by weight) Aminosilane coupling agent: 3-aminopropyltriethoxysilane (0.1 parts by mass) Polyurethane resin (0.2 parts by weight) Epoxy resin: Bisphenol A novolac type epoxy resin (0.2 parts by mass) Boric acid compound: orthoboric acid (0.2 parts by mass) (B-5) Blocked isocyanate: Biuret of hexamethylene diisocyanate blocked with ε-caprolactam (1.2 parts by mass) Aminosilane coupling agent: 3-aminopropyltriethoxysilane (0.1 parts by mass) Epoxy resin: Phenol novolac type epoxy resin (0.1 parts by mass) Boric acid compound: orthoboric acid (0.15 parts by mass) (B-6) Aminosilane coupling agent: 3-aminopropyltriethoxysilane (0.1 parts by mass) Polyurethane resin (0.2 parts by weight) Epoxy resin: Bisphenol A type epoxy resin (0.2 parts by mass) (B-7) Blocked isocyanate: hexamethylene diisocyanate trimer blocked with methyl ethyl ketoxime (0.8 parts by weight) Aminosilane coupling agent: 3-aminopropyltriethoxysilane (0.1 parts by mass) Epoxy resin: Bisphenol A type epoxy resin (0.1 parts by mass) (B-8) Blocked isocyanate: hexamethylene isocyanate trimer blocked with methyl ethyl ketoxime (1.2 parts by weight) Aminosilane coupling agent: 3-aminopropyltriethoxysilane (0.1 parts by mass) Polyurethane resin (0.2 parts by weight) Epoxy resin: Bisphenol A type epoxy resin (0.2 parts by mass)

[0085] <(C) Triazine derivative having a nitrogen-containing functional group> ·melamine

[0086] <(D) Boric acid compounds> Orthoboric acid

[0087] <(E) Carbon Black> Acetylene black

[0088] <(F) Polyolefin wax> Polyethylene wax

[0089] [evaluation] <Mechanical property evaluation> The polyacetal resin compositions in Tables 1 to 4 were put into an injection molding machine, and test pieces were prepared in accordance with ISO 3167. Using these test pieces, tensile strength (in accordance with ISO 527-1, 2), flexural strength (in accordance with ISO 178), and notched Charpy impact strength (measurement atmosphere: 23°C, 50% RH, in accordance with ISO 179·1eA) were measured. The evaluation results of the mechanical properties are shown in Tables 1 to 4.

[0090] <Hot water resistance evaluation> The test pieces prepared by the above method were immersed in an autoclave containing hot water at 120°C for one day, then removed and their tensile strength (tensile strength after hot water treatment) was measured under the same measurement conditions as those for the mechanical property evaluation. The evaluation results are shown in Tables 1 to 4.

[0091] [Table 1]

[0092] [Table 2]

[0093] [Table 3]

[0094] [Table 4]

[0095] As shown in Tables 1 to 4, it was found that by including a boric acid compound in the surface treatment agent for surface treating the glass fiber, a polyacetal resin composition having excellent mechanical properties and excellent hot water resistance can be obtained. [Industrial Applicability]

[0096] INDUSTRIAL APPLICABILITY The polyacetal resin composition of the present invention has excellent mechanical properties and hot water resistance, and is therefore expected to contribute to the development and widespread use of polyacetal resin compositions.

Claims

1. (A) 100 parts by mass of polyacetal resin, (B) 1 part by mass or more and 100 parts by mass or less of glass fiber, and (C) containing 0.002 parts by mass or more and 10 parts by mass or less of a triazine derivative having a nitrogen-containing functional group, The polyacetal resin composition, wherein the (B) glass fiber is surface-treated with a surface treatment agent containing at least one selected from a blocked isocyanate compound, an aminosilane coupling agent, an epoxy resin, and a polyurethane resin, and a boric acid compound.

2. The polyacetal resin composition according to claim 1 , wherein the (C) triazine derivative having a nitrogen-containing functional group is melamine.

3. The polyacetal resin composition according to claim 1 , further comprising: (D) 0.001 part by mass or more and 1.0 part by mass or less of a boric acid compound.

4. The polyacetal resin composition according to claim 3 , wherein the boric acid compound is orthoboric acid.

5. The polyacetal resin composition according to claim 1 , further comprising (E) 0.01 parts by mass or more and 15 parts by mass or less of carbon black.

6. The polyacetal resin composition according to claim 5 , wherein the carbon black is acetylene black.

7. The polyacetal resin composition according to claim 1 , further comprising: (F) 0.01 parts by mass or more and 5 parts by mass or less of a polyolefin wax.

8. The polyacetal resin composition according to claim 7, wherein the polyolefin wax is a polyethylene wax.

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