Polyacetal resin composition

Abstract

According to the present invention, a polyacetal resin composition having high hot water resistance and excellent manufacturability can be provided. The polyacetal resin composition of the present invention is a polyacetal resin composition containing the following components: (A) 100 parts by weight of polyacetal resin; (B) 1 to 100 parts by weight of glass fiber surface-treated by a blocked isocyanate compound, an aminosilane coupling agent and an epoxy resin; (C) 0.001 to 2 parts by weight of an organometallic compound selected from at least one organometallic compound having a metal selected from Zn, Sn, and Pb; and (D) 0.002 to 10 parts by weight of a triazine derivative having a nitrogen-containing functional group.

Description

Technical Field

[0001] This invention relates to polyacetal resin compositions. Prior Technology

[0002] Polyacetal resins possess excellent properties in terms of mechanical properties, thermal properties, electrical properties, lubricity, formability, impact resistance, and dimensional stability of molded products, and are widely used as structural materials or mechanical components in electronic devices, automotive components, and precision mechanical components. Furthermore, to enhance the mechanical properties of polyacetal resins, such as strength or rigidity, it is known to incorporate reinforcing materials such as glass-based inorganic fillers.

[0003] However, polyacetal resins lack reactivity, and glass-based inorganic fillers also lack reactivity. Therefore, when glass-based inorganic fillers are simply blended into polyacetal resins and melt-mixed, the adhesion between the two becomes insufficient, often failing to achieve the desired level of improvement in mechanical properties. Therefore, various methods have been proposed to improve the adhesion between polyacetal resins and glass-based inorganic fillers, thereby enhancing mechanical properties.

[0004] For example, there are known methods for adding glass-based inorganic fillers and boric acid compounds to polyacetal resin (see Patent Document 1), and methods for surface-treating the glass-based inorganic fillers by using blocked isocyanate or specific silane compounds (see Patent Document 2), etc. [Preliminary Technology Documents] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-151298 [Patent Document 2] Japanese Patent Application Publication No. 3-79631 Summary of the Invention

[0006] [The problem the invention aims to solve]

[0007] By using these methods to improve the chemical activity of glass-based inorganic fillers, the tensile strength, elongation, flexural strength, impact resistance, and hot water resistance of the polyacetal resin incorporating glass-based inorganic fillers can be enhanced. However, if the feeding rate of the glass-based inorganic fillers (especially chopped strands, rovings, etc.) is increased to improve productivity, a phenomenon known as fuzzing occurs during the feeding of the glass fibers, resulting in a problem that hinders stable production.

[0008] On the other hand, it is also required to further improve the hot water resistance of polyacetal resins that have been incorporated with glass-based inorganic fillers.

[0009] This invention was made to solve the problems mentioned above, and its purpose is to provide a polyacetal resin composition with high hot water resistance and excellent manufacturability. [Methods used to solve problems]

[0010] The objective of this invention is achieved by means of the following.

[0011] (1) A polyacetal resin composition comprising: (A) 100 parts by weight of polyacetal resin; (B) 1 part by weight and less than 100 parts by weight of glass fiber that has been surface-treated by end-capped isocyanate compound, aminosilane coupling agent and epoxy resin; (C) 0.001 parts by mass and 2 parts by mass of organometallic compounds containing metals selected from Zn, Sn, and Pb; and (D) 0.002 parts by mass and 10 parts by mass of a triazine derivative having a nitrogen-containing functional group. (2) The polyacetal resin composition as described in 1 above, wherein the aforementioned (C) is a carboxylate of an organometallic compound selected from Zn, Sn, and Pb. (3) The polyacetal resin composition as described in 1 above, wherein the organometallic compound of the aforementioned (C) having a metal selected from Zn, Sn, and Pb is a mixture of carboxylic acid and inorganic metal compound. (4) The polyacetal resin composition described in any one of 1 to 3 above, wherein the triazine derivative having a nitrogen-containing functional group in (D) above is melamine. [Invention Benefits]

[0012] According to the present invention, a polyacetal resin composition having high hot water resistance and excellent manufacturability can be provided. Simple Explanation of the Diagram

[0013] none. Implementation

[0014] [The form in which the invention is carried out]

[0015] Although the following describes specific embodiments of the present invention in detail, the present invention is not limited to any of the following embodiments, and appropriate modifications and implementations can be made within the scope of the purpose of the present invention.

[0016] <Polyacetal Resin Composition> The polyacetal resin composition of the present invention is characterized by comprising: (A) 100 parts by mass of polyacetal resin; (B) 1 part by mass and 100 parts by mass of glass fiber that has been surface-treated by a capped isocyanate compound, an aminosilane coupling agent and an epoxy resin; (C) 0.001 parts by mass and 2 parts by mass of at least one organometallic compound selected from organometallic compounds having metals selected from Zn, Sn and Pb; and (D) 0.002 parts by mass and 10 parts by mass of a triazine derivative having a nitrogen-containing functional group.

[0017] <(A) Polyacetal Resin> The polyacetal resin of the present invention (A) is a polymeric compound in which oxymethylene (-CH 2O-) is the main constituent unit. It may also be a polyoxymethylene homopolymer in which only oxymethylene is the constituent unit, or a copolymer, terpolymer, or block polymer in which oxymethylene is the main constituent unit and in small amounts contains other constituent units such as ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal, etc., which are derived from the constituent units of the comonomer.

[0018] Furthermore, polyacetal resins can be not only linear in structure, but also branched or cross-linked structures formed by copolymerizing comonomers with glycidyl ether structures, or conventional modified polyoxymethylene with other organic groups incorporated. They can also be mixtures of resins with linear structures and resins with branched and / or cross-linked structures.

[0019] There are no particular restrictions on the degree of polymerization of polyacetal resin, as long as it has melt-forming processability (for example, in accordance with ISO 1133, the melt flow rate (MFR) measured at 190°C and 2160g load is 1.0g / 10min or more and 100g / 10min or less).

[0020] <(B) Surface-treated glass fiber using end-capped isocyanate compounds, aminosilane coupling agents, and epoxy resin> The term (B) refers to glass fiber that has undergone surface treatment with end-capped isocyanate compounds, aminosilane coupling agents, and epoxy resin (hereinafter also referred to as "surface-treated glass fiber"). This means that the glass fiber has undergone surface treatment with end-capped isocyanate compounds, aminosilane coupling agents, and epoxy resin. The glass fiber only needs to undergo surface treatment with end-capped isocyanate compounds, aminosilane coupling agents, and epoxy resin, regardless of the order in which the surface treatment is performed.

[0021] That is, the surface-treated glass fiber of the present invention can be surface-treated by end-capped isocyanate compound and then surface-treated by aminosilane coupling agent and epoxy resin, or it can be surface-treated by aminosilane coupling agent and then surface-treated by end-capped isocyanate compound and epoxy resin.

[0022] Furthermore, the aforementioned glass fiber can also be surface-treated with an aminosilane coupling agent and epoxy resin, followed by a surface treatment with a capped isocyanate compound; or it can be surface-treated with an aminosilane coupling agent and a capped isocyanate compound, followed by a surface treatment with epoxy resin. Naturally, the glass fiber can also be surface-treated simultaneously with a capped isocyanate compound, an aminosilane coupling agent, and epoxy resin.

[0023] Furthermore, surface-treated glass fibers can also be surface-treated by adding polyurethane resin and / or polyacrylic resin (acrylic acid polymer alone, acrylate / methyl acrylate copolymer, acrylate / methyl methacrylate, etc.) and / or fluorescent whitening agent to end-capped isocyanate compounds, aminosilane coupling agents and epoxy resins.

[0024] Furthermore, whether the surface-treated glass fiber is surface-treated by end-capped isocyanate compounds, aminosilane coupling agents, and epoxy resins can be distinguished by solvent extraction of the glass fiber from the polyacetal resin composition and analysis of the extracted components using conventional analytical equipment.

[0025] Capped isocyanate compounds As a raw material for end-capped isocyanate compounds, any isocyanate compound that is a multifunctional isocyanate compound having two or more isocyanate groups in one molecule can be used without particular restrictions.

[0026] Examples of isocyanate compounds include aliphatic, alicyclic (hereinafter also referred to as "alicyclic"), and aromatic isocyanate compounds. Among these, from the viewpoint of compatibility or suitability with polyacetal resins, it is preferable to have a bifunctional aliphatic or alicyclic diisocyanate compound, an aromatic diisocyanate compound, or a polyisocyanate obtained by polymerizing such diisocyanate compounds.

[0027] Aliphatic diisocyanate compounds are preferably those with 4 or more carbon atoms and 30 or fewer carbon atoms, and more preferably those with 5 or more carbon atoms and 10 or fewer carbon atoms. Examples of such aliphatic diisocyanate compounds include tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene-1,6-diisocyanate, and lysine diisocyanate.

[0028] Alicyclic diisocyanate compounds are preferably those with 8 or more but less than 18 carbon atoms, and more preferably those with 10 or more but less than 15 carbon atoms. Examples of such alicyclic diisocyanate compounds include isoflavone diisocyanate, 1,3-bis(isocyanate methyl)-cyclohexane, and 4,4'-dicyclohexylmethane diisocyanate.

[0029] Examples of aromatic diisocyanate compounds include xylylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0030] Examples of polyisocyanates include compounds having at least two isocyanate groups per molecule, such as toluene diisocyanate or diphenylmethane diisocyanate; aromatic diisocyanate compounds such as m-phenylenedimethyl diisocyanate and α,α,α',α'-tetramethyl-m-phenylenedimethyl diisocyanate; aralkyl diisocyanate compounds such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate or isofrone diisocyanate; prepolymers containing isocyanate groups, such as those obtained by adding aliphatic or alicyclic diisocyanate compounds to polyols; prepolymers having isocyanuric acid rings, such as those obtained by cyclizing and trimerizing the above diisocyanate compounds; and polyisocyanates having a biuret structure, such as those obtained by reacting the above diisocyanate compounds with water.

[0031] From the viewpoint of impact resistance, durability, and ease of acquisition of the resulting composition, hexamethylene diisocyanate or polymers of hexamethylene diisocyanate (e.g., dimers, (cyclic) trimers, pentamers, heptamers, nonamers, undeterminers, or mixtures thereof) are preferred among the aforementioned isocyanate compounds. Furthermore, these isocyanate compounds can be used alone or in combination of two or more.

[0032] As the terminated isocyanate compound of the present invention, it can be obtained by terminating the reactive groups of the above-mentioned isocyanate compound using conventional methods and well-known terminating agents without particular limitation.

[0033] Examples of capping agents include oxime-based capping agents such as methyl ethyl ketone oxime, acetone oxime, cyclohexanone oxime, acetophenone oxime, and benzophenone oxime; phenol-based capping agents such as phenol, cresol, propofol, butyrol, and dibenzocresol; alcohol-based capping agents such as methanol, ethanol, butanol, 2-ethylhexanol, cyclohexanol, and ethylene glycol monoethyl ether; acetylamine-based capping agents such as ε-caprolactam; diketone-based capping agents such as diethyl malonate and acetoacetate; thiol-based capping agents such as thiophenol; urea-based capping agents such as thiourea; imidazole-based capping agents; carbamate-based capping agents; and bisulfite. Among these, acetylamine-based, oxime-based, and diketone-based capping agents are preferred.

[0034] By using a capped isocyanate compound, the capping agent dissociates from the isocyanate group when the polyacetal resin is melted. Therefore, the highly reactive isocyanate group can only react after melt mixing with the polyacetal resin, thus effectively promoting the reaction with the polyacetal resin.

[0035] Aminosilane Coupling Agents In the surface treatment of glass fibers of the present invention, an aminosilane coupling agent can be used. An aminosilane coupling agent refers to a compound containing, in one molecule, a silicon atom already bonded to an alkoxy group and a nitrogen-containing functional group.

[0036] Examples of aminosilane coupling agents include 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. Examples of aminosilane coupling agents include 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, and N,N'-bis-[3-(triethoxysilyl)propyl]hexamethylenediamine. Furthermore, these aminosilane coupling agents can be used alone or in combination of two or more.

[0037] Among these, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane and N-phenyl-3-aminopropyltrimethoxysilane are preferred, and 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane are even more preferred.

[0038] These aminosilane coupling agents readily achieve a synergistic effect due to their combination with end-capped isocyanate compounds, which can improve the adhesion between polyacetal resins and glass fibers.

[0039] Epoxy Resins The epoxy resin of the present invention can be any conventional epoxy resin. Examples of the epoxy resins described above include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, phenolic novolac or cresol novolac type epoxy resin, aliphatic epoxy resins and their hydrogenated or ether-modified forms, phenoxy resins, epoxypropyl ester type epoxy resins, epoxypropylamine type epoxy resins, cyclic aliphatic epoxy resins, and urethane-modified epoxy resins. Among these, bisphenol A type epoxy resin and phenolic novolac epoxy resins are preferred in terms of the bundle properties and hot water resistance of glass fibers. Furthermore, the present invention can use one or more epoxy resins selected from the above-mentioned types.

[0040] Glass fiber The diameter of the glass fibers used in this invention is not particularly limited, but is preferably 8 μm or more and 20 μm or less. If the diameter of the glass fibers is 8 μm or more, not only are the mechanical properties and hot water resistance of the molded articles improved, but also the occurrence of fuzzing caused by the deterioration of the fiber bundle structure is reduced, and the decrease in the productivity of the resin composition is suppressed. Furthermore, if the diameter of the single fiber is 20 μm or less, the strength of the resin composition can be improved. In addition, in this specification, the diameter of the glass fibers is the average of the diameters of 25 filament cross-sections measured according to JIS R 3420.

[0041] Although the glass fiber is surface-treated with end-capped isocyanate compound, aminosilane coupling agent, and epoxy resin, the preferred blending amounts of each, relative to 100 parts by weight of untreated glass fiber, are 0.1-10 parts by weight, 0.001-0.3 parts by weight, and 0.05-1 parts by weight, more preferably 0.3-3 parts by weight, 0.01-0.2 parts by weight, and 0.05-0.8 parts by weight. Furthermore, the preferred mass ratio of end-capped isocyanate compound, aminosilane coupling agent, and epoxy resin is 94-45:1-15:5-40, more preferably 92-50:2-12:6-38.

[0042] The amount of surface-treated glass fiber incorporated relative to 100 parts by weight of polyacetal resin is 1 part by weight or more and 100 parts by weight or less, preferably 5 parts by weight or more and 75 parts by weight or less, and more preferably 10 parts by weight or more and 60 parts by weight or less. If the amount of surface-treated glass fiber incorporated is 1 part by weight or more, the mechanical properties and hot water resistance of the molded article are significantly improved. If the amount incorporated is 100 parts by weight or less, the molding process becomes easier.

[0043] <(C) Organometallic compounds containing metals selected from Zn, Sn, and Pb> The so-called (C) of the present invention, which comprises organometallic compounds (hereinafter also referred to as "organometallic compounds") having metals selected from Zn, Sn, and Pb, refers to organometallic compounds having bonds between the aforementioned metals and carbon, metal complexes having coordinate bonds with the aforementioned metals, carboxylates of the aforementioned metals, and mixtures of carboxylic acids and inorganic metal compounds.

[0044] (C) Organometallic compounds with metal-carbon bonds Examples of organometallic compounds having the aforementioned metal-carbon bonds include dibutyltin dilaurate, dibutyltin di-2-ethylhexanoate, dioctyltin dilaurate, dibutyltin diacetate, dimethyltin dimaleate, dibutyltin dioxide, dioctyltin oxide, and other organotin compounds.

[0045] Examples of metal complexes having coordination bonds with the aforementioned metals include diketone complexes such as acetone tin, acetone lead, acetone zinc, acetone zinc hydrate, bis(2,6-dimethyl-3,5-heptadecane)zinc, bis(2,2,6,6-tetramethyl-3,5-heptadecane)zinc, bis(5,5-dimethyl-2,4-hexanedione)zinc, and bis(acetyl ethyl acetate)zinc.

[0046] Metallic Carboxylates Examples of carboxylates of the aforementioned metals include tin carboxylate series (tin acetate, tin propionate, tin octanoate, tin neodecanoate, tin laurate, tin myristate, tin palmitate, tin stearate, tin dodecanoate, montanoic acid). Lead carboxylic acid series (lead acetate, lead acetate trihydrate, lead propionate, lead octanoate, lead neodecanoate, lead laurate, lead myristate, lead palmitate, lead stearate, lead docosate, lead lignite, lead 12-hydroxystearate, lead cyclohexanebutyrate, lead 2-ethylhexanoate, lead oleate, lead octanoate, lead naphthenate, lead benzoate, lead t-butylbenzoate, lead salicylate, lead naphthenate, lead polyacrylate, lead polymethacrylate, lead polymethacrylate, etc.), lead carboxylic acid series (lead acetate, lead acetate trihydrate, lead propionate, lead octanoate, lead neodecanoate, lead laurate, lead myristate, lead palmitate, lead stearate, lead docosate, lead lignite, lead 12-hydroxystearate, lead cyclohexanebutyrate, lead 2-ethylhexanoate, lead oleate, lead octanoate, lead naphthenate, lead benzoate, lead t-butylbenzoate, lead salicylate, lead naphthenate, lead polyacrylate, lead polymethacrylate, lead methyl methacrylate). Lead acetate, or mixtures thereof, etc.), zinc carboxylic acid series (zinc acetate, zinc acetate dihydrate, zinc propionate, zinc octanoate, zinc neodecanoate, zinc laurate, zinc myristate, zinc palmitate, zinc stearate, zinc docosate, zinc lignite, zinc 12-hydroxystearate, zinc cyclohexanebutyrate, zinc 2-ethylhexanoate, zinc oleate, zinc octenate, zinc naphthenate, zinc benzoate, zinc t-butylbenzoate, zinc salicylate, zinc glycolate, zinc lactate, zinc oxalate, zinc malonate, zinc succinate, zinc glutarate, zinc adipic acid, zinc heptaate, zinc octanoate, zinc azelaate, zinc sebacic acid, zinc dodecanoate, zinc citrate, zinc polyacrylate, zinc polymethacrylate, or mixtures thereof, etc.), etc.

[0047] Furthermore, the carboxylates of metals can also be complexes of metals selected from at least one of tin, lead and zinc and other metals (e.g., zinc stearate-calcium stearate complex, zinc stearate-barium stearate complex, etc.).

[0048] Mixtures of carboxylic acids and inorganic metal compounds As a mixture of carboxylic acids and inorganic metal compounds, it includes mixtures of carboxylic acids (acetic acid, propionic acid, octanoic acid, neodecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, icosanoic acid, linalic acid, 12-hydroxystearic acid, cyclohexanebutyric acid, 2-ethylhexanoic acid, oleic acid, octenic acid, naphthenic acid, benzoic acid, t-butylbenzoic acid, salicylic acid, naphthenic acid, glycolic acid, lactic acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, polyacrylic acid, polymethacrylic acid, etc.) and inorganic metal compounds (tin oxide, tin hydroxide, lead oxide, lead hydroxide, zinc oxide, zinc hydroxide, etc.).

[0049] Among these organometallic compounds, metal carboxylates and mixtures of carboxylic acids and inorganic metal compounds are preferred.

[0050] Relative to 100 parts by weight of polyacetal resin, the amount of organometallic compound incorporated in this invention is 0.001 parts by weight or more and 2 parts by weight or less, preferably 0.01 to 0.5 parts by weight.

[0051] <(D) Triazine derivatives with nitrogen-containing functional groups> The polyacetal resin composition of the present invention contains (D) a triazine derivative having a nitrogen-containing functional group.

[0052] Examples of triazine derivatives (hereinafter also referred to as "triazine derivatives") having nitrogen-containing functional groups used in this invention include melamine, N-hydroxymethyl melamine, N,N'-dihydroxymethyl melamine, N,N',N'-trihydroxymethyl melamine, N,N,N',N'-tetrahydroxymethyl melamine, and other hydroxymethyl melamines, or mixtures thereof; alkoxymethyl melamine (described in Japanese Patent Application Publication No. 55-157645), melamine prepolymers. (As recorded in Japanese Patent Publication No. 7-116346) alkoxymethyl derivatives of hydroxymethyl melamine, etc.; guanidine compounds such as benzoguanamine, acetoguanamine, and 2,4-diamino-6-butyl-sym-triazine; N-butylmelamine, N-phenylmelamine, N,N-diphenylmelamine, N,N-diallylmelamine, N,N',N-triphenylmelamine, etc. Ammeline, 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, methylene melamine, ethylene dimelamine, triguanamine, melamine cyanurate, ethylene dimelamine cyanurate, triguanamine cyanurate, etc.

[0053] These triazine derivatives can be used alone or in combination of two or more. Among them, guanidine compounds such as benzoguanidine or acetylguanidine, hydroxymethyl melamine, alkoxymethyl derivatives of hydroxymethyl melamine, and melamine are preferred, and melamine is even more preferred.

[0054] In this invention, relative to 100 parts by mass of polyacetal resin, the amount of (D) having a triazine derivative containing a nitrogen-functional group is preferably 0.002 parts by mass or more and 10 parts by mass or less, more preferably 0.01 parts by mass or more and 2 parts by mass or less, and particularly preferably 0.03 parts by mass or more and 1 part by mass or less.

[0055] If the content of the above-mentioned (D) triazine derivative is 0.002 parts by mass or more, the production stability of the polyacetal resin composition can be improved; if it is 10 parts by mass or less, exudation from the polyacetal resin composition can be suppressed.

[0056] The present invention improves both the hot water resistance and manufacturability of polyacetal resin compositions by using (B) surface-treated glass fibers, (C) organometallic compounds containing metals selected from Zn, Sn, and Pb, and (D) triazine derivatives.

[0057] The inventors speculate that the excellent hot water resistance and manufacturability of the polyacetal resin composition of the present invention are due to the beneficial effect of the organometallic compounds and triazine derivatives on the bonding between the surface-treated glass fiber and the molecular chain ends of the polyacetal resin.

[0058] <Other Additives> Other Glass Fibers The polyacetal resin composition of the present invention may also contain glass fibers that have been surface-treated by a conventional coupling agent other than the aforementioned aminosilane coupling agent. The coupling agent is used to improve the wettability or adhesion of the glass fibers to the polyacetal resin. Examples of coupling agents include silane-based, titanate-based, aluminum-based, chromium-based, zirconium-based, and borane-based coupling agents. Among these, silane-based coupling agents are preferred.

[0059] Examples of silane-based coupling agents include vinylalkoxysilanes, epoxyalkoxysilanes, mercaptoalkoxysilanes, and allylalkoxysilanes. Examples of vinylalkoxysilanes include vinyltriethoxysilanes, vinyltrimethoxysilanes, and vinyltris(2-methoxyethoxy)silanes.

[0060] Examples of epoxyalkoxysilanes include 3-epoxypropoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-epoxypropoxypropyltriethoxysilane.

[0061] Examples of mercaptoalkoxysilanes include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.

[0062] Examples of allylalkoxysilanes include 3-diallylaminopropyltrimethoxysilane, 3-allylaminopropyltrimethoxysilane, and 3-allylthiopropyltrimethoxysilane.

[0063] Examples of titanate-based coupling agents include titanium-i-(propoxy octylene glycolate), tetra-n-butoxytitanium, and tetra(2-ethylhexyloxy)titanium. These coupling agents can be used alone or in combination of two or more.

[0064] Various stabilizers and additives Furthermore, the polyacetal resin composition of the present invention may contain conventional inorganic, organic, and metallic fibrous, plate-like, or granular fillers other than glass fibers, provided that the content does not significantly reduce the performance of the target molded article. Examples of such fillers include talc, mica, wollastonite, carbon fiber, and glass beads.

[0065] Furthermore, various known stabilizers and additives can be incorporated. Examples of stabilizers include hindered phenol compounds, hindered amine compounds, hydroxides of alkali or alkaline earth metals, inorganic compounds such as boric acid compounds, and carboxylates. Examples of additives include colorants such as dyes and pigments, fluorescent whitening agents, lubricants, nucleating agents, release agents, antistatic agents, and surfactants—general additives for thermoplastic resins.

[0066] The type of boric acid compound is not particularly limited and may be any of orthoboric acid, metaboric acid, tetraboric acid, or a dehydrated product of orthoboric acid. Among these, orthoboric acid is preferred. The amount of boric acid incorporated is preferably 0.001 parts by mass or more and 1.0 parts by mass or less, more preferably 0.01 parts by mass or more and 0.5 parts by mass or less.

[0067] <Method for manufacturing polyacetal resin composition> Examples of methods for manufacturing polyacetal resin compositions include: mixing components (A) to (D) and then melt-blending them using a single-axis or biaxial extruder to produce granules of the polyacetal resin composition; and first manufacturing granules (masterbatches) with different compositions, then mixing (diluting) the granules in a specified amount to obtain a molded article. Furthermore, examples of the above manufacturing methods also include: impregnating the above components (terminated isocyanate compound, aminosilane coupling agent, and epoxy resin) into glass fibers (roving) that have undergone specific surface treatment, then manufacturing granules of the polyacetal resin composition and molding them.

[0068] Furthermore, in order to ensure good dispersibility of the additives, a preferred method is to pulverize part or all of the polyacetal resin as the matrix during the manufacture of the polyacetal resin composition, mix it with other components, and then extrude it. [Example]

[0069] The present invention will be described in more detail below with reference to embodiments, but the present invention is not limited to the following embodiments.

[0070] <Preparation of Polyacetal Resin Compositions> In the amounts shown in Tables 1 and 2, (B) surface-treated glass fibers, (C) organometallic compounds, and (D) triazine derivatives having nitrogen-containing functional groups were incorporated into (A) 100 parts by weight of polyacetal resin, and melt-blended using a biaxial extruder at a cylinder temperature of 200°C to produce the granular polyacetal resin compositions of the Examples and Comparative Examples. Furthermore, the surface-treated glass fibers were added via a side-feed method. The units of measurement in the tables are parts by weight.

[0071] [Table 1]

[0072] [Table 2]

[0073] The components of (A) to (D) shown in Tables 1 and 2 are as follows. <(A) Polyacetal Resin> (A-1) Polyacetal resin (making 96.7% by weight of triacetal) Polyacetal copolymer synthesized by copolymerization of 1,3-dioxolane with 3.3% by mass (melt flow value (measured according to ISO 1133, at 190°C and 2160 g load): 45 g / 10 min) (A-2) Polyacetal resin (making 96.7% by weight of triacetal) Polyacetal copolymer synthesized by copolymerization of 1,3-dioxolane with 3.3% by mass (melt flow value (measured according to ISO 1133, at 190°C and 2160g load): 9g / 10min)

[0074] <(B) Surface-treated glass fiber> The glass fiber is made of strands with a single fiber diameter of 10μm. (B-1) to (B-9) are materials used for surface treatment of the above glass fiber.

[0075] (B-1) Terminal isocyanate compound of hexamethylene diisocyanate capped by methyl ethyl ketone oxime: 0.8 parts by weight Aminosilane coupling agent: 0.1 parts by weight Bisphenol A type epoxy resin: 0.1 parts by weight (B-2) Terminal isocyanate compound of hexamethylene diisocyanate capped by methyl ethyl ketone oxime: 0.6 parts by weight Aminosilane coupling agent: 0.1 parts by weight Bisphenol A type epoxy resin: 0.1 parts by weight (B-3) A capped isocyanate compound consisting of a hexamethylene diisocyanate cyclic trimer capped by methyl ethyl ketone oxime: 1.2 parts by weight Aminosilane coupling agent: 0.1 parts by weight Bisphenol A type epoxy resin: 0.2 parts by weight (B-4) End-capped isocyanate compound of hexamethylene diisocyanate cyclic trimer terminated by ε-caprolactam: 0.8 parts by weight Aminosilane coupling agent: 0.15 parts by weight Bisphenol A type epoxy resin: 0.15 parts by weight (B-5) A terminal isocyanate compound of isoflavone diisocyanate terminated by methyl ethyl ketone oxime: 1.2 parts by weight Aminosilane coupling agent: 0.1 parts by weight Phenolic epoxy resin: 0.2 parts by weight (B-6) End-capped isocyanate of hexamethylene diisocyanate cyclic trimer capped by methyl ethyl ketone oxime: 0.6 parts by weight A capped isocyanate compound consisting of a hexamethylene diisocyanate cyclic trimer terminated by ε-caprolactam: 0.2 parts by weight Aminosilane coupling agent: 0.1 parts by weight Bisphenol A type epoxy resin: 0.1 parts by weight (B-7) End-capped isocyanate compound of hexamethylene diisocyanate capped by methyl ethyl ketone oxime: 0.8 parts by weight Aminosilane coupling agent: 0.1 parts by weight (B-8) End-capped isocyanate compound of hexamethylene diisocyanate capped by methyl ethyl ketone oxime: 0.8 parts by weight Bisphenol A type epoxy resin: 0.1 parts by weight (B-9) Aminosilane coupling agent: 0.1 parts by weight Bisphenol A type epoxy resin: 0.1 parts by weight

[0076] Furthermore, the aminosilane coupling agent described in (B-1) to (B-9) above is 3-aminopropyltriethoxysilane.

[0077] <(C) Organometallic Compounds> (C-1) Zinc stearate (C-2)12-Hydroxystearic acid zinc (C-3) Zinc acetate (C-4) Stearic acid / zinc oxide = 2 / 1 (Morby) (C-5) Calcium stearate

[0078] <(D) Triazine derivatives with nitrogen-containing functional groups> (D-1) Melamine

[0079] <Physical Property Evaluation> For the granular polyacetal resin compositions of the Examples and Comparative Examples, test pieces were prepared using an injection molding machine in accordance with ISO 3167. The tensile strength TS (initial TS, in MPa) was then measured in accordance with ISO 527-1 and 2. The measurement environment was 23°C and 50% RH. The results are shown in Tables 3 and 4.

[0080] <Hot Water Resistance Evaluation> Test specimens prepared in accordance with ISO 3167 were immersed in an autoclave containing hot water at 120°C for one day, and then removed. Tensile strength (TS after hot water immersion, in MPa) was measured under the same conditions as the physical property evaluation described above. The tensile strength retention rate (TS retention rate) was calculated by setting the initial TS measured in the physical property evaluation above to 100%. The results are shown in Tables 3 and 4.

[0081] <Productivity Evaluation> The fiber fuzzing near the feed section was visually observed during side feeding of surface-treated glass fibers, and evaluated as follows. A and B represent the practical application level. The results are shown in Tables 3 and 4. A: No fuzzing was observed. B: Slight fuzzing was observed. C: The supply of glass fiber changes due to fuzzing.

[0082] [Table 3]

[0083] [Table 4]

[0084] As shown in Tables 3 and 4, the molding system of the polyacetal resin composition, which is made by incorporating (A) 100 parts by mass of polyacetal resin, (B) 1 to 100 parts by mass of glass fiber that has been surface-treated by end-capped isocyanate compound, aminosilane coupling agent and epoxy resin, (C) 0.001 to 2 parts by mass of organometallic compound selected from at least one organometallic compound having metals selected from Zn, Sn and Pb, and (D) 0.002 to 10 parts by mass of triazine derivative having nitrogen-containing functional groups, exhibits excellent hot water resistance and excellent manufacturability. [Industrial Utilization]

[0085] The polyacetal resin composition of the present invention not only has mechanical properties, but also high hot water resistance and excellent manufacturability. Therefore, it can be widely used as a structural material or mechanical component in electronic equipment, automotive components, precision mechanical components, etc., and thus can contribute to the industry.

[0086] none

Claims

1. A polyacetal resin composition comprising: (A) 100 parts by weight of polyacetal resin; (B) 1 to 100 parts by weight of glass fiber surface-treated by a blocked isocyanate compound, an aminosilane coupling agent and an epoxy resin; (C) 0.001 to 2 parts by weight of an organometallic compound having a metal selected from Zn, Sn, and Pb; and (D) 0.002 to 3 parts by weight of a triazine derivative having a nitrogen-containing functional group.

2. The polyacetal resin composition as claimed in claim 1, wherein, The aforementioned (C) is a carboxylate of an organometallic compound selected from Zn, Sn, and Pb.

3. The polyacetal resin composition as claimed in claim 1, wherein, The aforementioned (C) is an organometallic compound containing metals selected from Zn, Sn, and Pb, which is a mixture of carboxylic acid and inorganic metal compound.

4. The polyacetal resin composition of any one of claims 1 to 3, wherein, The aforementioned (D) triazine derivative with nitrogen-containing functional groups is melamine.