Polyacetal resin composition

Abstract

According to the present invention, a polyacetal resin composition having high hot water resistance and excellent productivity can be provided. The polyacetal resin composition of the present invention comprises (B) 1 part by mass or more and 100 parts by mass or less of glass fiber surface-treated with a blocked isocyanate compound, an aminosilane coupling agent and an epoxy resin, (C) 0.001 part by mass or more and 1.0 part by mass or less of a boric acid compound, and (D) 0.002 parts by mass or more and 10 parts by mass or less of a triazine derivative having a nitrogen-containing functional group, relative to 100 parts by mass of (A) a polyacetal resin.

Description

Technical Field

[0001] The present invention relates to polyacetal resin compositions. Background Art

[0002] Polyacetal resin has excellent properties in terms of mechanical properties, thermal properties, electrical properties, sliding properties, moldability, impact resistance, dimensional stability of molded products, etc., and is widely used as structural materials and mechanism parts for electrical equipment, automobile parts, precision machinery parts, etc. In addition, in order to improve the mechanical properties of polyacetal resin, such as strength and rigidity, it is known to mix reinforcing materials such as glass-based inorganic fillers.

[0003] However, polyacetal resin lacks activity, and glass-based inorganic fillers also lack activity. Therefore, when simply mixing glass-based inorganic fillers in polyacetal resin and melt-kneading, the adhesion of the two becomes insufficient, and the improvement of mechanical properties as expected cannot be obtained in most cases. Therefore, various methods for improving the adhesion of polyacetal resin and glass-based inorganic fillers and improving mechanical properties have been proposed.

[0004] For example, there are known methods of adding a glass-based inorganic filler and a boric acid compound to a polyacetal resin (see Patent Document 1), and further surface-treating the glass-based inorganic filler with a blocked isocyanate or a specific silane compound (see Patent Document 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 9-151298

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 3-79631 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] According to these methods, by increasing the chemical activity of the glass-based inorganic filler, the tensile strength, tensile elongation, bending strength, impact resistance, and hot water resistance of the polyacetal resin mixed with the glass-based inorganic filler can be improved. However, if the feed rate of the glass-based inorganic filler (especially glass fibers such as chopped fibers and rovings) is increased in order to improve productivity, the glass fibers sometimes become fluffy during feeding, which results in a problem of hindering stable production.

[0011] On the other hand, further improvement in hot water resistance of polyacetal resins blended with glass-based inorganic fillers is also required.

[0012] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a polyacetal resin composition having high hot water resistance and excellent productivity.

[0013] Solutions for solving problems

[0014] The objects of the present invention are achieved as follows.

[0015] 1. A polyacetal resin composition, comprising, relative to 100 parts by mass of (A) polyacetal resin:

[0016] (B) 1 part by mass or more and 100 parts by mass or less of glass fibers surface-treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin;

[0017] (C) 0.001 parts by mass or more and 1.0 parts by mass or less of a boric acid compound; and

[0018] (D) 0.002 parts by mass or more and 10 parts by mass or less of a triazine derivative having a nitrogen-containing functional group.

[0019] 2. The polyacetal resin composition according to item 1 above, wherein the (C) boric acid compound is orthoboric acid.

[0020] 3. The polyacetal resin composition according to 1 or 2 above, wherein the triazine derivative (D) having a nitrogen-containing functional group is melamine.

[0021] Effects of the Invention

[0022] According to the present invention, a polyacetal resin composition having high hot water resistance and excellent productivity can be provided. DETAILED DESCRIPTION

[0023] Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments at all and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

[0024] <Polyacetal resin composition>

[0025] The polyacetal resin composition of the present invention is characterized in that it contains, relative to 100 parts by mass of (A) polyacetal resin: (B) 1 part by mass or more and 100 parts by mass or less of glass fiber surface-treated with a blocked isocyanate compound, an aminosilane coupling agent and an epoxy resin, (C) 0.001 part by mass or more and 1.0 part by mass or less of a boric acid compound, and (D) 0.002 parts by mass or more and 10 parts by mass or less of a triazine derivative having a nitrogen-containing functional group.

[0026] <(A) Polyacetal resin>

[0027] The polyacetal resin (A) of the present invention is an oxymethylene (-CH 2 The polymer compound having oxymethylene as the main structural unit may be a polyoxymethylene homopolymer having only oxymethylene as the structural unit, or a copolymer, dimer or block polymer having oxymethylene as the main structural unit and containing a small amount of other structural units, such as structural units derived from comonomers such as ethylene oxide, 1,3-dioxolane, 1,4-butanediol formal, etc.

[0028] In addition, the polyacetal resin may have not only a linear structure but also a branched or cross-linked structure copolymerized with a comonomer having a glycidyl ether structure, or may be a known modified polyoxymethylene into which other organic groups are introduced. In addition, there is no particular limitation on the degree of polymerization of the polyacetal resin, as long as it has melt moldability (for example, a melt flow rate (MFR) measured at 190° C. and a load of 2160 g according to ISO 1133 of 1.0 g / 10 min or more and 100 g / 10 min or less).

[0029] <(B) Glass fiber surface-treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin>

[0030] (B) Glass fibers surface-treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin (hereinafter, also referred to as "surface-treated glass fibers") refer to glass fibers surface-treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin. The glass fibers only need to be surface-treated with the blocked isocyanate compound, the aminosilane coupling agent, and the epoxy resin, regardless of the order of the surface treatment.

[0031] That is, the surface-treated glass fiber of the present invention may be one that is surface-treated with a blocked isocyanate compound and then surface-treated with an aminosilane coupling agent and an epoxy resin, or one that is surface-treated with an aminosilane coupling agent and then surface-treated with a blocked isocyanate compound and an epoxy resin.

[0032] In addition, the glass fiber may be surface treated with an aminosilane coupling agent and an epoxy resin and then surface treated with a blocked isocyanate compound, or may be surface treated with an aminosilane coupling agent and a blocked isocyanate compound and then surface treated with an epoxy resin. Of course, the glass fiber may also be surface treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin simultaneously.

[0033] Furthermore, the surface-treated glass fiber can be surface-treated by adding a polyurethane resin and / or a polyacrylic resin (acrylic homopolymer, acrylic acid / methyl acrylate copolymer, acrylic acid / methyl methacrylate, etc.) and / or a fluorescent brightener to the blocked isocyanate compound, the aminosilane coupling agent and the epoxy resin.

[0034] It should be noted that whether the surface-treated glass fiber is surface-treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin can be distinguished by extracting the glass fiber from a polyacetal resin composition solvent and analyzing the extracted components using a known analysis device.

[0035] By using glass fibers surface-treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin, the adhesion between the polyacetal resin and the glass fibers can be improved.

[0036] 《Blocked isocyanate compounds》

[0037] As the isocyanate compound serving as a raw material of the blocked isocyanate compound, any polyfunctional isocyanate compound having two or more isocyanate groups in one molecule can be used without particular limitation.

[0038] Examples of isocyanate compounds include aliphatic, alicyclic (hereinafter also referred to as "alicyclic") and aromatic isocyanate compounds. Among these, from the viewpoint of compatibility and compatibility with the polyacetal resin, bifunctional aliphatic or alicyclic diisocyanate compounds, aromatic diisocyanate compounds, and polyisocyanates obtained by polymerizing these diisocyanate compounds are preferred.

[0039] The aliphatic diisocyanate compound 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 such aliphatic diisocyanate compounds include tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene-1,6-diisocyanate, lysine diisocyanate, and the like.

[0040] The alicyclic diisocyanate compound preferably has 8 to 18 carbon atoms, and more preferably has 10 to 15 carbon atoms. Examples of such alicyclic diisocyanate compounds include isophorone diisocyanate, 1,3-bis(isocyanatemethyl)-cyclohexane, and 4,4'-dicyclohexylmethane diisocyanate.

[0041] Examples of the aromatic diisocyanate compound include xylylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0042] 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 meta-xylylene diisocyanate, α,α,α',α'-tetramethyl-meta-xylylene diisocyanate; aralkyl diisocyanate compounds such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate or isophorone diisocyanate; isocyanate group-containing prepolymers obtained by addition reaction of aliphatic or alicyclic diisocyanate compounds with polyols; prepolymers having isocyanurate rings obtained by cyclotrimerization of the above diisocyanate compounds; or polyisocyanates having a biuret structure obtained by reacting the above diisocyanate compounds with water.

[0043] From the viewpoint of the impact resistance, durability and availability of the obtained composition, among the above-mentioned isocyanate compounds, hexamethylene diisocyanate or a polymer of hexamethylene diisocyanate (e.g., dimer, (cyclic) trimer, pentamer, heptamer, nonamer, undecamer, or a mixture thereof, etc.) is preferred. It should be noted that these isocyanate compounds can be used alone or in combination of two or more.

[0044] As the blocked isocyanate compound of the present invention, there can be used, without particular limitation, any isocyanate compound obtained by blocking the reactive group of the above-mentioned isocyanate compound with a known blocking agent in accordance with a known method.

[0045] Examples of the blocking agent include oxime-based blocking agents such as methyl ethyl ketone oxime, acetone oxime, 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; thiol-based blocking agents such as thiophenol; urea-based blocking agents such as thiourea; imidazole-based blocking agents; carbamic acid-based blocking agents; hydrogen sulfite, etc. Among these, lactam-based blocking agents, oxime-based blocking agents, and diketone-based blocking agents are preferred.

[0046] By using a blocked isocyanate compound, the blocking agent dissociates from the isocyanate group when the polyacetal resin is melted. Therefore, the highly reactive isocyanate group can react only during melt kneading with the polyacetal resin and thereafter, thereby effectively advancing the reaction with the polyacetal resin.

[0047] 《Aminosilane coupling agent》

[0048] An aminosilane coupling agent is used for the surface treatment of the glass fiber of the present invention. The aminosilane coupling agent is a compound containing a silicon atom to which an alkoxy group is bonded and a functional group containing a nitrogen atom in one molecule.

[0049] 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. In addition, these aminosilane coupling agents may be used alone or in combination of two or more.

[0050] 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 more preferred.

[0051] These aminosilane coupling agents are likely to produce a synergistic effect in combination with a blocked isocyanate compound, and can improve the adhesion between the polyacetal resin and the glass fiber.

[0052] Epoxy resin

[0053] The epoxy resin of the present invention can use a known epoxy resin. Examples of the above-mentioned epoxy resins include: bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, phenol novolac type or cresol novolac type epoxy resin and other novolac type epoxy resins, aliphatic epoxy resins and their hydrogenated or ether modified products, phenoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, cycloaliphatic epoxy resins, and carbamate modified epoxy resins. Among these, bisphenol A type epoxy resin and phenol novolac type epoxy resin are preferred from the aspects of the bundling and hot water resistance of glass fibers. It should be noted that the present invention can select one or more epoxy resins from the above-mentioned epoxy resins for use.

[0054] Fiberglass

[0055] The single fiber diameter of the glass fiber used in the present invention is not particularly limited, preferably 8 μm or more and 20 μm or less. If the single fiber diameter of the glass fiber is 8 μm or more, not only the mechanical properties and hot water resistance of the molded product become good, but also the occurrence of fuzzing caused by the deterioration of the bundling of the glass fiber can be reduced, and the reduction in the productivity of the resin composition can be suppressed. In addition, if the single fiber diameter is 20 μm or less, the strength of the resin composition can be improved. It should be noted that in this specification, the single fiber diameter of the glass fiber refers to the average value of the diameters of 25 multifilament cross sections measured according to JIS R 3420.

[0056] The glass fiber is surface treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin, and the amount of each compounded is preferably 0.1 to 10 parts by mass, 0.001 to 0.3 parts by mass, and 0.05 to 1 parts by mass, and more preferably 0.3 to 3 parts by mass, 0.01 to 0.2 parts by mass, and 0.05 to 0.8 parts by mass, relative to 100 parts by mass of the glass fiber before treatment. In addition, the mass ratio of the blocked isocyanate compound, the aminosilane coupling agent, and the epoxy resin is preferably 94 to 45: 1 to 15: 5 to 40, and more preferably 92 to 50: 2 to 12: 6 to 38.

[0057] The blending amount of the surface-treated glass fiber is 1 part by mass or more and 100 parts by mass or less, preferably 5 parts by mass or more and 75 parts by mass or less, more preferably 10 parts by mass or more and 60 parts by mass or less, relative to 100 parts by mass of the polyacetal resin. If the blending amount of the surface-treated glass fiber is 1 part by mass or more, the mechanical properties of the visible molded product and the hot water resistance are fully improved, and if the blending amount is 100 parts by mass or less, the molding process becomes easy.

[0058] <(C) Boric acid compounds>

[0059] The polyacetal resin composition of the present invention contains (C) a boric acid compound.

[0060] Examples of the boric acid compound (C) include orthoboric acid, metaboric acid, tetraboric acid, and dehydrated orthoboric acid. Of these, orthoboric acid is preferred. The amount of the boric acid compound (C) is greater than or equal to 0.001 mass part and less than or equal to 1.0 mass part, preferably greater than or equal to 0.01 mass part and less than or equal to 0.5 mass part, relative to 100 mass parts of the polyacetal resin. If the boric acid compound is within the above range, the desired effect can be obtained on hot water resistance and productivity.

[0061] Even if the polyacetal resin composition contains an acid, the effect of the present invention cannot be obtained if the acid is a general inorganic acid or organic acid. Even if hydrochloric acid or phosphoric acid is used as an inorganic acid, or formic acid or acetic acid is used as an organic acid, the mechanical properties, hot water resistance, and productivity cannot reach the level of the effect based on the boric acid compound.

[0062] <(D) Triazine derivatives having a nitrogen-containing functional group>

[0063] The polyacetal resin composition of the present invention contains (D) a triazine derivative having a nitrogen-containing functional group.

[0064] (D) Examples of triazine derivatives having a nitrogen-containing functional group (hereinafter also referred to as "triazine derivatives") include melamine, N-methylolmelamine, N,N'-dimethylolmelamine, N,N',N"-trimethylolmelamine, N,N,N',N"-tetramethylolmelamine and other methylolmelamines, or mixtures thereof, alkoxymethylmelamine (described in Japanese Unexamined Patent Publication No. 55-157645), Alkoxymethyl derivatives of methylolmelamine such as melamine prepolymer (described in Japanese Patent Publication No. 7-116346), guanamine compounds such as benzoguanamine, methylguanamine, 2,4-diamino-6-butyl-s-triazine, N-butylmelamine, N-phenylmelamine, N,N-diphenylmelamine, N,N-diallylmelamine, N,N',N-triphenylmelamine, 2-oxy-4,6-diamino-s-triazine Triazine, 2,4-diamino-6-benzyloxy-s-triazine, 2,4-diamino-6-butoxy-s-triazine, 2,4-diamino-6-cyclohexyl-s-triazine, 2,4-diamino-6-chloro-s-triazine, 2,4-diamino-6-mercapto-s-triazine, 2,4-dioxy-6-amino-s-triazine, 2-oxy-4,6-diamino-s-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 (succiguanamine)], 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 di (melamine) cyanurate, triguanamine cyanurate, etc.

[0065] These triazine derivatives may be used alone or in combination of two or more thereof. Among these, guanamine compounds such as benzoguanamine and methylguanamine, methylolmelamine, methylolmelamine alkoxymethyl derivatives, and melamine are preferred, and melamine is more preferred.

[0066] In the present invention, the amount of the triazine derivative (D) having a nitrogen-containing functional group is preferably 0.002 to 10 parts by mass, more preferably 0.01 to 2 parts by mass, particularly preferably 0.03 to 1 part by mass, based on 100 parts by mass of the polyacetal resin.

[0067] When the content of the triazine derivative (D) is at least 0.002 parts by mass, the production stability of the polyacetal resin composition can be improved, and when it is at most 10 parts by mass, bleed-out from the polyacetal resin composition can be suppressed.

[0068] The present invention can improve both the hot water resistance and productivity of the polyacetal resin composition by using (B) the surface-treated glass fiber, (C) the boric acid compound and (D) the triazine derivative in combination.

[0069] The inventors speculate that the reason why the polyacetal resin composition of the present invention is excellent in hot water resistance and productivity is that the boric acid compound and the triazine derivative exert some favorable influence on the bonding between the surface-treated glass fiber and the molecular chain terminal of the polyacetal resin.

[0070] <Other additives>

[0071] Other glass fibers

[0072] The polyacetal resin composition of the present invention may contain glass fibers surface-treated with a known coupling agent other than the aminosilane coupling agent. The coupling agent is used to improve the wettability and adhesion of the glass fibers to the polyacetal resin. Examples of the coupling agent include silane-based, titanate-based, aluminum-based, chromium-based, zirconium-based, and borane-based coupling agents. Among these, silane-based coupling agents are preferred.

[0073] Examples of the silane coupling agent include vinylalkoxysilane, epoxyalkoxysilane, mercaptoalkoxysilane, allylalkoxysilane, etc. Examples of the vinylalkoxysilane include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, etc.

[0074] Examples of epoxyalkoxysilane include 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0075] Examples of the mercaptoalkoxysilane include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.

[0076] Examples of the allylalkoxysilane include 3-diallylaminopropyltrimethoxysilane, 3-allylaminopropyltrimethoxysilane, and 3-allylthiopropyltrimethoxysilane.

[0077] Examples of titanate coupling agents include titanium-isopropoxy suberate, tetra-n-butoxytitanium, tetrakis(2-ethylhexyloxy)titanium, etc. These coupling agents may be used alone or in combination of two or more.

[0078] 《Various stabilizers and additives》

[0079] The polyacetal resin composition of the present invention may be blended with various known stabilizers and additives. Examples of stabilizers include hindered phenol compounds, hindered amine compounds, nitrogen-containing basic compounds, alkali or alkaline earth metal oxides, hydroxides, inorganic salts, and carboxylates.

[0080] Examples of the additives include general additives for thermoplastic resins, such as colorants such as dyes and pigments, fluorescent whitening agents, lubricants, nucleating agents, mold release agents, antistatic agents, and surfactants.

[0081] In addition, the polyacetal resin composition of the present invention may contain known inorganic, organic, and metal fiber-shaped, plate-shaped, powdery, and granular fillers other than glass fiber as long as the performance of the target molded product is not significantly reduced. Examples of the above-mentioned fillers include talc, mica, wollastonite, carbon fiber, glass beads, etc.

[0082] <Method for producing polyacetal resin composition>

[0083] The polyacetal resin composition of the present invention can be easily produced by a known method for producing a resin composition.

[0084] Examples of the method for producing the polyacetal resin composition include: a method for producing pellets of the polyacetal resin composition by mixing the above-mentioned components (A) to (D) and then melt-kneading them in a single-screw extruder or a twin-screw extruder; a method for temporarily producing pellets (master batches) of different compositions and mixing (diluting) the pellets in a predetermined amount to obtain a molded article; etc. In addition, examples of the above-mentioned production method also include: a method for producing pellets of the polyacetal resin composition and molding the same after impregnating the above-mentioned components (blocked isocyanate compound, aminosilane coupling agent and epoxy resin) into glass fibers (rovings) subjected to a specific surface treatment.

[0085] In the production of the polyacetal resin composition, a method is preferably to pulverize a part or all of the polyacetal resin as a matrix and mix it with other components before extrusion in order to improve the dispersibility of the additives.

[0086] Example

[0087] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples at all.

[0088] <Production of polyacetal resin composition>

[0089] In 100 parts by mass of (A) polyacetal resin, (B) surface-treated glass fiber, (C) boric acid compound and (D) triazine derivative having nitrogen-containing functional group were blended in the amounts shown in Tables 1 and 2, and melt-kneaded in a twin-screw extruder at a barrel temperature of 200° C. to produce pelletized polyacetal resin compositions of Examples and Comparative Examples. It should be noted that the surface-treated glass fiber was added by side feeding. The units of the values ​​in the table are parts by mass.

[0090] [Table 1]

[0091]

[0092] [Table 2]

[0093]

[0094] The components (A) to (D) shown in Tables 1 and 2 are as follows.

[0095] <(A) Polyacetal resin>

[0096] (A-1)

[0097] Polyacetal resin (polyacetal copolymer obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane (melt flow value (measured at 190° C. and a load of 2160 g in accordance with ISO1133): 45 g / 10 minutes)

[0098] (A-2)

[0099] Polyacetal resin (polyacetal copolymer obtained by copolymerizing 96.7 mass % of trioxane and 3.3 mass % of 1,3-dioxolane (melt flow value (measured in accordance with ISO1133 at 190° C. and a load of 2160 g): 9 g / 10 minutes)

[0100] <(B) Surface-treated glass fiber>

[0101] The glass fiber used was chopped fiber having a single fiber diameter of 10 μm. (B-1) to (B-9) are materials used for surface treatment of the glass fiber.

[0102] (B-1)

[0103] Blocked isocyanate compound of hexamethylene diisocyanate blocked with methyl ethyl ketone oxime: 0.8 parts by mass

[0104] Aminosilane coupling agent: 0.1 parts by mass

[0105] Bisphenol A epoxy resin: 0.1 parts by mass

[0106] (B-2)

[0107] Blocked isocyanate compound of hexamethylene diisocyanate blocked with methyl ethyl ketone oxime: 0.6 parts by mass

[0108] Aminosilane coupling agent: 0.1 parts by mass

[0109] Bisphenol A epoxy resin: 0.1 parts by mass

[0110] (B-3)

[0111] Blocked isocyanate compound of hexamethylene diisocyanate cyclic trimer blocked with methyl ethyl ketone oxime: 1.2 parts by mass

[0112] Aminosilane coupling agent: 0.1 parts by mass

[0113] Bisphenol A epoxy resin: 0.2 parts by mass

[0114] (B-4)

[0115] Blocked isocyanate compound of hexamethylene diisocyanate cyclic trimer blocked with ε-caprolactam: 0.8 parts by mass

[0116] Aminosilane coupling agent: 0.15 parts by mass

[0117] Bisphenol A epoxy resin: 0.15 parts by mass

[0118] (B-5)

[0119] Blocked isocyanate compound of isophorone diisocyanate blocked with methyl ethyl ketone oxime: 1.2 parts by mass

[0120] Aminosilane coupling agent: 0.1 parts by mass

[0121] Phenol novolac type epoxy resin: 0.2 parts by mass

[0122] (B-6)

[0123] Blocked isocyanate compound of hexamethylene diisocyanate cyclic trimer blocked with methyl ethyl ketone oxime: 0.6 parts by mass

[0124] Blocked isocyanate of hexamethylene diisocyanate cyclic trimer blocked with ε-caprolactam: 0.2 parts by mass

[0125] Aminosilane coupling agent: 0.1 parts by mass

[0126] Bisphenol A epoxy resin: 0.1 parts by mass

[0127] (B-7)

[0128] Blocked isocyanate compound of hexamethylene diisocyanate blocked with methyl ethyl ketone oxime: 0.8 parts by mass

[0129] Aminosilane coupling agent: 0.1 parts by mass

[0130] (B-8)

[0131] Blocked isocyanate compound of hexamethylene diisocyanate blocked with methyl ethyl ketone oxime: 0.8 parts by mass

[0132] Bisphenol A epoxy resin: 0.1 parts by mass

[0133] (B-9)

[0134] Aminosilane coupling agent: 0.1 parts by mass

[0135] Bisphenol A epoxy resin: 0.1 parts by mass

[0136] It should be noted that the aminosilane coupling agent described in (B-1) to (B-9) above is 3-aminopropyltriethoxysilane.

[0137] <(C) Boric acid compounds>

[0138] (C-1) Orthoboric acid

[0139] <(D) Triazine derivatives having a nitrogen-containing functional group>

[0140] (D-1) Melamine

[0141] <Physical property evaluation>

[0142] For the pelletized polyacetal resin compositions of the examples and comparative examples, test pieces were made using an injection molding machine in accordance with ISO3167. Then, the tensile strength (initial TS, unit: MPa) in accordance with ISO527-1 and 2 was measured. The measurement atmosphere was 23°C and 50% RH. The results are shown in Tables 3 and 4. It should be noted that in Comparative Example 5, foaming occurred during the production and no sample could be obtained.

[0143] <Hot water resistance evaluation>

[0144] The test piece was immersed in an autoclave containing hot water at 120°C for 4 days and then taken out. The tensile strength (TS after hot water immersion, unit: MPa) was measured under the same measurement conditions as the physical property evaluation. The tensile strength retention rate (TS retention rate) was calculated by taking the initial TS value measured in the above physical property evaluation as 100%. The results are shown in Tables 3 and 4.

[0145] <Productivity Evaluation>

[0146] When the surface-treated glass fibers were side-fed, the fuzzing of the glass fibers near the feed portion was evaluated visually as follows. A and B are practical levels. The results are shown in Tables 3 and 4.

[0147] A: The occurrence of fuzzing was not observed.

[0148] B: The occurrence of fuzz was slightly observed.

[0149] C: The supply amount of glass fiber varies due to the occurrence of fuzz.

[0150] [Table 3]

[0151]

[0152] [Table 4]

[0153]

[0154] From the results in Tables 3 and 4, it can be seen that the molded article of the polyacetal resin composition containing (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 surface-treated with a blocked isocyanate compound, an aminosilane coupling agent and an epoxy resin, (C) 0.001 part by mass or more and 1.0 part by mass or less of a boric acid compound, and (D) 0.002 parts by mass or more and 10 parts by mass or less of a triazine derivative having a nitrogen-containing functional group has excellent hot water resistance and excellent productivity.

[0155] Industrial Applicability

[0156] The polyacetal resin composition of the present invention has not only excellent mechanical properties but also high hot water resistance and excellent productivity, and therefore can be widely used as structural materials and mechanism parts for electrical equipment, automobile parts, precision machinery parts, etc., thereby making it possible to contribute to the industry.

Claims

1. A polyacetal resin composition, comprising, relative to 100 parts by mass of (A) polyacetal resin: (B) 1 part by mass or more and 100 parts by mass or less of glass fibers surface-treated with a blocked isocyanate compound, an aminosilane coupling agent, and an epoxy resin, wherein: The epoxy resin is at least one selected from the group consisting of bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AD ​​epoxy resin, phenol novolac type or cresol novolac type epoxy resin; (C) 0.001 parts by mass or more and 1.0 parts by mass or less of a boric acid compound; and (D) 0.002 parts by mass or more and 10 parts by mass or less of a triazine derivative having a nitrogen-containing functional group.

2. The polyacetal resin composition according to claim 1, wherein The (C) boric acid compound is orthoboric acid.

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

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