Polyacetal resin composition and molded article

Abstract

To provide a polyacetal resin composition which can achieve further improvement of physical properties such as mechanical strength, hot water resistance, creep resistance and low warpage, while using a heteromorphic cross-sectional glass fiber.SOLUTION: A polyacetal resin composition contains, with respect to 100 pts.mass of (A) a polyacetal resin, 1 to 100 pts.mass of (B) a heteromorphic cross-sectional glass fiber, 0.1 to 10 pts.mass of (C) a polyfunctional isocyanate compound, 0.001 to 3 pts.mass of (D) one or more binding agents selected from the group consisting of an organometal compound containing a metal element selected from the group consisting of Sn, Zn and Pb, a boric acid compound and a quaternary onium salt compound, and 0.002 to 10 pts.mass of (E) a triazine derivative having a nitrogen-containing functional group.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Polyacetal resin is widely used as an engineering plastic mainly for electrical and electronic parts, automotive parts and other various machine parts because it has an excellent balance of mechanical properties, chemical resistance, sliding properties, etc., and is easy to process. In order to further improve the mechanical properties, various fillers are generally added to polyacetal resin. Examples of such fillers include glass fibers. Glass fibers are widely used not only for polyacetal resin but also for various engineering plastics to improve their mechanical strength. Glass fibers having a circular cross-sectional shape are generally used. However, when using general glass fibers having a circular cross-sectional shape, the mechanical properties and shrinkage rate can be improved with an increase in the filling amount, but the warping of the obtained resin molded product tends to increase due to increased anisotropy. Therefore, in recent years, it has been proposed to use irregular cross-section glass fibers having a non-circular cross-section (see Patent Document 1). By using such irregular cross-section glass fibers, the warping of the resin molded product can be reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-316079 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, by adding irregular cross-section glass fibers to a resin composition, it is possible to reduce warpage of a resin molded product obtained by molding the resin composition. In addition, in Patent Document 1, a polyfunctional cyanate ester compound is used as a binder to impart adhesion at the interface between the irregular cross-section glass fiber and the polyacetal resin. However, even if such a binder is used, the interface adhesion between the irregular cross-section glass fiber and the polyacetal resin is not sufficient, and the mechanical strength and creep resistance are insufficient, leaving room for improvement.

[0005] The present invention has been made in consideration of the above-mentioned problems in the conventional art, and an object of the present invention is to provide a polyacetal resin composition and a molded article which use modified cross-section glass fibers and which are capable of achieving further improvements in physical properties such as mechanical strength, hot water resistance, creep resistance, and low warpage. [Means for solving the problem]

[0006] One aspect of the present invention that solves the above problems is as follows. (1) (A) per 100 parts by mass of polyacetal resin, (B) 1 to 100 parts by mass of irregular cross section glass fiber, (C) 0.1 to 10 parts by mass of a polyfunctional isocyanate compound; (D) 0.001 to 3 parts by mass of one or more binders selected from the group consisting of organometallic compounds containing a metal element selected from the group consisting of Sn, Zn, and Pb, boric acid compounds, and quaternary onium salt compounds; (E) 0.002 to 10 parts by mass of a triazine derivative having a nitrogen-containing functional group.

[0007] (2) The polyacetal resin composition according to (1) above, wherein the (B) irregular cross-section glass fiber is a glass fiber having a flat cross-sectional shape in which the ratio of the major axis of the cross-section to the minor axis of the cross-section (irregularity ratio) is 1.2 or more.

[0008] (3) The polyacetal resin composition according to (1) or (2), wherein the polyfunctional isocyanate compound (C) is at least one compound selected from the group consisting of 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and blocked isocyanate compounds thereof.

[0009] (4) The polyacetal resin composition according to any one of (1) to (3), wherein the (C) polyfunctional isocyanate compound is at least one compound selected from the group consisting of a 4,4'-diphenylmethane diisocyanate polymer, an isophorone diisocyanate polymer, a 1,6-hexamethylene diisocyanate polymer, a 2,4-tolylene diisocyanate polymer, a 2,6-tolylene diisocyanate polymer, and blocked isocyanate compounds thereof.

[0010] (5) The polyacetal resin composition according to any one of (1) to (4), wherein the (D) binder is at least one compound selected from the group consisting of fatty acid zinc salts, boric acid, quaternary phosphonium halide salts, quaternary ammonium halide salts, quaternary phosphonium carboxylate salts, and quaternary ammonium carboxylate salts.

[0011] (6) The polyacetal resin composition according to any one of (1) to (5) above, wherein the (D) binder is at least one compound selected from the group consisting of zinc stearate, zinc 12-hydroxystearate, orthoboric acid, ethyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, choline acetate, and choline chloride.

[0012] (7) The polyacetal resin composition according to any one of (1) to (6), wherein the (E) triazine derivative having a nitrogen-containing functional group is at least one compound selected from the group consisting of melamine, a melamine formaldehyde adduct, and benzoguanamine.

[0013] (8) A molded article obtained by molding the polyacetal resin composition according to any one of (1) to (7) above. Effect of the Invention

[0014] According to the present invention, it is possible to provide a polyacetal resin composition and a molded article which use modified cross section glass fibers and which are capable of achieving further improvements in physical properties such as mechanical strength, hot water resistance, creep resistance, and low warpage. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <Polyacetal resin composition> The polyacetal resin composition of the present embodiment contains, per 100 parts by mass of (A) polyacetal resin, (B) 1 to 100 parts by mass of modified cross section glass fiber, (C) 0.1 to 10 parts by mass of a polyfunctional isocyanate compound, (D) 0.001 to 3 parts by mass of one or more binders selected from the group consisting of organometallic compounds containing a metal element selected from the group consisting of Sn, Zn, and Pb, boric acid compounds, and quaternary onium salt compounds, and (E) 0.002 to 10 parts by mass of a triazine derivative having a nitrogen-containing functional group.

[0016] The polyacetal resin composition of the present embodiment contains (C) a polyfunctional isocyanate compound, (D) a specific binder, and (E) a triazine derivative having a nitrogen-containing functional group in a predetermined amount, together with (B) the irregular cross-section glass fiber. By containing such components (C) to (E), the interfacial adhesion between (A) the polyacetal resin and (B) the irregular cross-section glass fiber is improved, and physical properties such as mechanical strength, hot water resistance, and creep resistance can be improved. Each component of the polyacetal resin composition of the present embodiment will be described in detail below.

[0017] [(A) Polyacetal resin] In this embodiment, the polyacetal resin (A) is a polymeric compound having an oxymethylene group (-CHO-) as a main constituent unit, and may be either a polyoxymethylene homopolymer in which the only constituent unit is an oxymethylene group, or a copolymer, terpolymer, or block polymer in which the main constituent unit is an oxymethylene group and a small amount of other constituent units, for example, constituent units derived from comonomers such as ethylene oxide, 1,3-dioxolane, and 1,4-butanediol formal.

[0018] In addition, the polyacetal resin may be not only linear in molecule but also one having a branched or crosslinked structure obtained by copolymerizing a comonomer having a glycidyl ether structure, or may be a known modified polyoxymethylene into which other organic groups have been introduced, or may be a mixture of a linear resin and a resin having a branched or crosslinked structure.

[0019] The polyacetal resin is not particularly limited with respect to its degree of polymerization, and may be any resin having melt moldability (for example, a melt flow value (MFR) of 1.0 g / 10 min or more and 100 g / 10 min or less at 190° C. and a load of 2160 g in accordance with ISO 1133).

[0020] [(B) Irregular cross-section glass fiber] The polyacetal resin composition of the present embodiment contains 1 to 100 parts by mass of (B) modified cross section glass fiber per 100 parts by mass of (A) polyacetal resin. By containing (B) modified cross section glass fiber, in combination with (C) polyfunctional isocyanate compound, (D) binder, and (E) triazine derivative having a nitrogen-containing functional group, it is possible to realize improvements in physical properties such as mechanical strength, creep resistance, and low warpage.

[0021] In this embodiment, the irregular cross-section glass fiber means a glass fiber whose cross section perpendicular to the longitudinal direction of the glass fiber has a shape that is not a so-called substantially perfect circle, such as an elongated flat shape such as an oval, cocoon shape, or ellipse shape. In addition, as the irregular cross section glass fiber, irregular cross section glass fiber obtained by the manufacturing method described in JP-B-4-32775, Japanese Patent No. 33369674, Japanese Patent No. 5505597, Japanese Patent No. 7075017, and International Publication WO2020 / 04033 can be used. The composition of the modified cross section glass fiber used in the polyacetal resin composition of this embodiment may be any composition that can be turned into glass fiber from molten glass, and examples of such composition include an E glass composition, an A glass composition, a C glass composition, a D glass composition, an H glass composition, an R glass composition, an S glass composition, a T glass composition, an AR glass composition, an NE glass composition, and an ECR glass composition (boron-free and / or fluorine-free glass composition). The modified cross section glass fiber used in the polyacetal resin composition of the present embodiment is preferably surface-treated with a silane coupling agent, and may be surface-treated with a sizing agent having a film-forming ability, such as an epoxy resin, a urethane resin, or an acid polymer.

[0022] From the viewpoint of improving physical properties such as mechanical strength, creep resistance, and low warpage, the (B) modified cross-section glass fiber preferably has a flat cross-sectional shape with a ratio of the major axis of the cross-section to the minor axis of the cross-section (modification ratio) of 1.2 or more. The modification ratio is more preferably 1.5 to 10, and further preferably 1.8 to 8. As the modified cross-section glass fiber, any glass having a fibrous shape can be used without any problem. Specific examples include chopped strand glass fiber, milled glass fiber, and glass fiber roving. Among these, chopped strand glass fiber and milled glass fiber are particularly preferred from the viewpoint of productivity. Furthermore, chopped strand glass fiber is more preferred for improving the creep resistance of the resin molded product. These modified cross-section glass fibers may be used alone or in combination of two or more.

[0023] Examples of modified cross section glass fibers having an oval cross section include chopped strand and oval FF manufactured by Nitto Boseki Co., Ltd., chopped strand and oval FGF manufactured by Nippon Electric Glass Co., Ltd., chopped strand and flat CS manufactured by Central Glass Fiber Co., Ltd. Examples of modified cross section glass fibers having a cocoon-shaped cross section include chopped strand and cocoon-shaped HIS manufactured by Nitto Boseki Co., Ltd.

[0024] The polyacetal resin composition of the present embodiment contains 1 to 100 parts by mass of (B) modified cross section glass fiber per 100 parts by mass of (A) polyacetal resin, but if the amount of (B) modified cross section glass fiber is less than 1 part by mass, the physical properties such as mechanical strength, hot water resistance, creep resistance and low warpage properties become insufficient, and if it exceeds 100 parts by mass, the melt fluidity is significantly reduced. The content of the (B) modified cross section glass fiber is preferably 3 to 80 parts by mass, more preferably 5 to 60 parts by mass.

[0025] [(C) Polyfunctional isocyanate compound] The polyacetal resin composition of the present embodiment contains 0.1 to 10 parts by mass of the polyfunctional isocyanate compound (C) relative to 100 parts by mass of the polyacetal resin (A). As described above, the polyfunctional isocyanate compound (C) is used to improve the interfacial adhesion between the polyacetal resin (A) and the modified cross section glass fiber (B).

[0026] (C) The polyfunctional isocyanate compound is a compound having two or more isocyanate groups in one molecule, and examples of such compounds include aromatic polyfunctional isocyanates, alicyclic polyfunctional isocyanates, and aliphatic polyfunctional isocyanates.

[0027] Examples of the (C) polyfunctional isocyanate compound include 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, triphenylmethane-4,4',4"-triisocyanate, polymethylene polyphenyl polyisocyanate, and blocked isocyanate compounds thereof. The (C) polyfunctional isocyanate compound may be a polymer. Examples of the polymer include a dimer, a trimer, a pentamer, a heptamer, a nonamer, an eleven-mer, and mixtures thereof. Among them, at least one compound selected from the group consisting of 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and blocked isocyanate compounds thereof is preferred. Alternatively, at least one compound selected from the group consisting of 4,4'-diphenylmethane diisocyanate multimers, isophorone diisocyanate multimers, 1,6-hexamethylene diisocyanate multimers, 2,4-tolylene diisocyanate multimers, 2,6-tolylene diisocyanate multimers, and blocked isocyanate compounds thereof is preferred.

[0028] The polyacetal resin composition of the present embodiment contains 0.1 to 10 parts by mass of the polyfunctional isocyanate compound (C) relative to 100 parts by mass of the polyacetal resin (A), but if the amount is less than 0.1 part by mass, the improvement in the interfacial adhesion between the polyacetal resin (A) and the modified cross section glass fiber (B) becomes insufficient, and if the amount exceeds 10 parts by mass, discoloration and generation of foreign matter occur. The content of the polyfunctional isocyanate compound (C) is preferably 0.2 to 7 parts by mass, more preferably 0.3 to 5 parts by mass.

[0029] [(D) Binder] The polyacetal resin composition of the present embodiment contains 0.001 to 3 parts by mass of (D) one or more binders selected from the group consisting of organometallic compounds containing a metal element selected from the group consisting of Sn, Zn, and Pb, boric acid compounds, and quaternary onium salt compounds, relative to 100 parts by mass of (A) polyacetal resin. As described above, (D) binder is used to improve the interfacial adhesion between (A) polyacetal resin and (B) modified cross section glass fiber.

[0030] (D) As a binder, the organometallic compound containing a metal element selected from Sn, Zn and Pb includes saturated or unsaturated fatty acid tin, fatty acid zinc, fatty acid lead, metal salts of polymeric carboxylic acids (poly(zinc)acrylate, zinc salt of ethylene-(meth)acrylic acid copolymer, etc.), metal salts of 1,3-diketones (tin acetylacetone, zinc acetylacetone, etc.), metal salts of dehydroacetic acid (zinc dehydroacetate, etc.). Here, as the fatty acid, fatty acids having 1 to 30 carbon atoms such as acetic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, eicosapentanoic acid, docosapentaenoic acid, docosahexaenoic acid, etc. are preferred. In addition, between saturated fatty acids and unsaturated fatty acids, saturated fatty acids are preferred from the viewpoint of thermal stability. Among the organometallic compounds, fatty acid zinc is preferred. Specifically, zinc stearate, zinc 12-hydroxystearate, etc. are included.

[0031] (D) Examples of the boric acid compound as a binder include boric acid and dehydration condensates of boric acid. Specific examples include orthoboric acid (H3BO3), metaboric acid, tetraboric acid, and other boric acids. Among these, orthoboric acid is preferred.

[0032] (D) Examples of the quaternary onium salt compound as a binder include quaternary phosphonium salts, quaternary ammonium salts, etc. Preferred are quaternary phosphonium halide salts and quaternary ammonium halide salts, respectively, and specifically, ethyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, and choline chloride are preferred. Further, quaternary phosphonium carboxylates and quaternary ammonium carboxylates are preferred, and specifically, choline acetate is preferred.

[0033] These (D) binders may be used in combination of two or more kinds, and it is particularly preferable to use a boric acid compound in combination with a quaternary onium salt. In the polyacetal resin composition of the present embodiment, 0.001 to 3 parts by mass of (D) binder is contained per 100 parts by mass of (A) polyacetal resin, but if it is less than 0.001 part by mass, the improvement of the interface adhesion between (A) polyacetal resin and (B) modified cross section glass fiber becomes insufficient, and if it exceeds 3 parts by mass, foaming of strands occurs during melt kneading, formaldehyde odor is generated, and the color of the molded product deteriorates. The content of (D) binder is preferably 0.002 to 2 parts by mass, more preferably 0.003 to 1 part by mass.

[0034] [(E) Triazine derivatives having nitrogen-containing functional groups] The polyacetal resin composition of the present embodiment contains 0.002 to 10 parts by mass of (E) a triazine derivative having a nitrogen-containing functional group relative to 100 parts by mass of (A) a polyacetal resin. By containing (E) a triazine derivative having a nitrogen-containing functional group, hot water resistance and creep resistance can be significantly improved.

[0035] In the present embodiment, the (E) triazine derivative having a nitrogen-containing functional group is preferably at least one compound selected from melamine, a melamine formaldehyde adduct, and benzoguanamine.

[0036] In the polyacetal resin composition of the present embodiment, the triazine derivative having a nitrogen-containing functional group (E) is contained in an amount of 0.002 to 10 parts by mass relative to 100 parts by mass of the polyacetal resin (A), but if the amount is less than 0.002 parts by mass, the hot water resistance and creep resistance cannot be improved, and if the amount is more than 10 parts by mass, the triazine derivative will bleed out onto the surface of the molded article. The amount is preferably 0.005 to 1 part by mass, and more preferably 0.01 to 0.5 parts by mass.

[0037] [Other stabilizers and additives] The polyacetal resin composition of the present embodiment may further contain various known stabilizers to enhance its stability, and may further contain various known additives to improve its physical properties depending on the intended use.

[0038] Examples of additives include various stabilizers (antioxidants, anti-acid agents, etc.), ultraviolet absorbers, light stabilizers, formaldehyde scavengers, colorants (carbon black, etc.), release agents, nucleating agents, antistatic agents, sliding agents, other surfactants, heterogeneous polymers, etc. In addition, fibrous, powdery, or plate-like fillers such as circular cross-section glass fibers, inorganic, organic, or metallic fillers may be used alone or in combination, so long as they do not significantly impair the performance of the composition of the present embodiment.

[0039] [Preparation of polyacetal resin composition] The polyacetal resin composition according to the present embodiment can be easily prepared by a known method generally used for preparing conventional resin compositions. For example, (1) a method of mixing all the components constituting the composition, feeding the mixture to an extruder and melt-kneading the mixture to obtain a pellet-shaped composition, (2) a method of feeding a part of the components constituting the composition from the main feed port of an extruder and the remaining components from a side feed port, melt-kneading the mixture to obtain a pellet-shaped composition, or (3) a method of preparing pellets having different compositions by extrusion or the like, mixing the pellets to adjust the composition to a desired composition, etc. can be adopted.

[0040] <Molded products> The molded article of the present embodiment is obtained by molding the polyacetal resin composition. The method for producing the molded article using the polyacetal resin composition of the present embodiment is not particularly limited, and a known method can be adopted. For example, the polyacetal resin composition of the present embodiment can be produced by feeding the polyacetal resin composition of the present embodiment into an extruder, melt-kneading the composition to form pellets, feeding the pellets into an injection molding machine equipped with a predetermined mold, and injection molding the composition.

[0041] Examples of molded products of this embodiment include automobile parts such as door locks, door handles, window regulators (carrier plates), power window switch housing parts, and other door-related parts; seat belt peripheral parts such as seat belt slip rings and press buttons; pulleys, wiper device parts; sunroof device parts; convenience store switch parts: parts such as clips; fuel-related parts such as fuel pump modules, valves, and gasoline tank flanges; office automation parts such as printer and copier parts, personal computer parts such as keyboard parts (plunger parts), communication equipment parts such as mobile phone and facsimile parts, electrical equipment parts, and electronic equipment parts. EXAMPLES

[0042] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples.

[0043] [Examples 1 to 15, Comparative Examples 1 to 10] In each of the Examples and Comparative Examples, (B) glass fiber, (C) polyfunctional isocyanate compound, (D) binder, and (E) triazine derivative having a nitrogen-containing functional group were blended in the amounts (parts by mass) shown in Tables 1 to 3 into 100 parts by mass of polyacetal resin, and melt-kneaded in an extruder with a cylinder temperature of 200° C. to prepare pellet-shaped polyacetal resin compositions according to the Examples and Comparative Examples.

[0044] The materials used in Tables 1 to 3 are as follows. The units for the compositions are parts by mass. (A) Polyacetal resin (A-1) Polyacetal resin (polyacetal copolymer (POM) obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane, melt flow value (measured in accordance with ISO133 at 190°C and a load of 2160 g): 45 g / 10 min) (A-2) Polyacetal resin (polyacetal copolymer (POM) obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane, melt flow value (measured in accordance with ISO113 at 190°C and a load of 2160 g): 9 g / 10 min)

[0045] (B) Irregular cross-section glass fiber (B-1) Flat glass fiber (Nitto Boseki Co., Ltd., chopped strand, CSG3PA830, long diameter / short diameter ratio: 4) (B-2) Flat glass fiber (manufactured by Nitto Boseki Co., Ltd., chopped strand, long diameter / short diameter ratio: 6) (B-3) Oval glass fiber (Nippon Electric Glass Co., Ltd., chopped strand, ECST03T-187-FGF, long diameter / short diameter ratio: 4) (B-4) Cocoon-shaped glass fiber (Nitto Boseki Co., Ltd., chopped strand, CSH3PA850, long diameter / short diameter ratio: 2) (B-5) Cocoon-shaped glass fiber (Nitto Boseki Co., Ltd., chopped strand, CSH3PA860S, long diameter / short diameter ratio: 2) (B'-1) Circular glass fiber (Owens Corning, chopped strand, ECS03T-668, long diameter / short diameter ratio: 1, fiber diameter = 13 μm)

[0046] (C) Polyfunctional isocyanate compound (C-1) Isophorone diisocyanate trimer (IPDI trimer, Evonik, VESTANAT T1890 / 100) (C-2) 1,6-hexamethylene diisocyanate trimer (HDI trimer, Asahi Kasei Chemicals Corporation, Duranate TPA-100) (C-3) 4,4'-Diphenylmethane diisocyanate (MDI)

[0047] (D) Binder (D-1) Zinc stearate (D-2) Zinc 12-hydroxystearate (D-3) Orthoboric acid (D-4) Ethyltriphenylphosphonium bromide (D-5) Choline acetate (D-6) Choline chloride

[0048] (E) Triazine derivatives having nitrogen-containing functional groups (E-1) Melamine (E-2) Melamine formaldehyde adduct (Nikaredin S-260, manufactured by Nippon Carbide Industries Co., Ltd.) (E-3) Benzoguanamine

[0049] <Physical property evaluation> Using the pellet-shaped compositions prepared in each of the Examples and Comparative Examples, test pieces were molded in an injection molding machine in accordance with ISO3167. Then, measurements were carried out for tensile strength in accordance with ISO527-1,2, bending strength in accordance with ISO178, and Charpy impact strength (notched, 23°C) in accordance with ISO179·1eA. The measurement atmosphere was 23°C and 50% RH. The evaluation results are shown in Tables 1 to 3.

[0050] <Hot water resistance evaluation> The above-mentioned tensile test piece was used according to ISO3167, and was immersed in an autoclave containing hot water at 120°C for one day, then removed and the tensile strength (tensile strength after hot water treatment, unit: MPa) was measured under the same measurement conditions as for the physical property evaluation. The evaluation results are shown in Tables 1 to 3.

[0051] <Creep resistance evaluation> Using a tensile test piece conforming to ISO 1367, a load of 40 MPa was applied at 80° C. in air under high temperature and high load conditions in a creep tester, and the time until the test piece broke was measured. The evaluation results are shown in Tables 1 to 3.

[0052] <Flatness evaluation> A 120 mm square flat test piece (2 mm thick) was molded, placed on a flat surface plate, and the maximum deformation of the test piece (where the gap between the surface plate and the test piece was the largest) was measured as the amount of deformation. The evaluation results are shown in Tables 1 to 3.

[0053] <Mold shrinkage evaluation> After molding a 120 mm square flat plate-shaped test piece (thickness 2 mm), the mold shrinkage rate (%) was measured in the resin flow direction and in the direction perpendicular to the resin flow direction (referred to as the perpendicular direction in the table). The evaluation results are shown in Tables 1 to 3.

[0054] [Table 1]

[0055] [Table 2]

[0056] [Table 3]

[0057] From Tables 1 to 3, it can be seen that in Examples 1 to 15, good results were obtained in all the evaluations. In particular, Example 15, which used boric acid (boric acid compound) and a quaternary ammonium salt (quaternary onium salt compound) in combination, showed an excellent evaluation result. In contrast, Comparative Example 2 and Comparative Example 9, which are the same as Examples 2 and 8, respectively, except that a glass fiber having a circular cross section was used, were inferior to the corresponding Examples in all the evaluation results. In addition, Comparative Examples 5, 6, 7, and 8, which are the same as Examples 2, 11, 10, and 5, respectively, except that (C) polyfunctional isocyanate compound was not used, were inferior to the corresponding Example 2 in all the evaluation results. Furthermore, Comparative Example 4, which is the same as Example 2 except that (D) binder was not used, was inferior to Example 2 in all the evaluation results.

Claims

1. (A) per 100 parts by mass of polyacetal resin, (B) 1 to 100 parts by mass of irregular cross section glass fiber; (C) 0.1 to 10 parts by mass of a polyfunctional isocyanate compound; (D) 0.001 to 3 parts by mass of one or more binders selected from the group consisting of organometallic compounds containing a metal element selected from the group consisting of Sn, Zn, and Pb, boric acid compounds, and quaternary onium salt compounds; (E) 0.002 to 10 parts by mass of a triazine derivative having a nitrogen-containing functional group.

2. 2. The polyacetal resin composition according to claim 1, wherein the modified cross section glass fiber (B) is a glass fiber having a flat cross section in which the ratio of the major axis of the cross section to the minor axis of the cross section (modification ratio) is 1.2 or more.

3. 3. The polyacetal resin composition according to claim 1, wherein the polyfunctional isocyanate compound (C) is at least one compound selected from the group consisting of 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and blocked isocyanate compounds thereof.

4. 3. The polyacetal resin composition according to claim 1, wherein the polyfunctional isocyanate compound (C) is at least one compound selected from the group consisting of a 4,4'-diphenylmethane diisocyanate polymer, an isophorone diisocyanate polymer, a 1,6-hexamethylene diisocyanate polymer, a 2,4-tolylene diisocyanate polymer, a 2,6-tolylene diisocyanate polymer, and blocked isocyanate compounds thereof.

5. 3. The polyacetal resin composition according to claim 1 or 2, wherein the binder (D) is at least one compound selected from the group consisting of fatty acid zinc salts, boric acid, halide quaternary phosphonium salts, halide quaternary ammonium salts, quaternary phosphonium carboxylates, and quaternary ammonium carboxylates.

6. 3. The polyacetal resin composition according to claim 1, wherein the binder (D) is at least one compound selected from the group consisting of zinc stearate, zinc 12-hydroxystearate, orthoboric acid, ethyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, choline acetate, and choline chloride.

7. 3. The polyacetal resin composition according to claim 1, wherein the (E) triazine derivative having a nitrogen-containing functional group is at least one compound selected from the group consisting of melamine, a melamine formaldehyde adduct, and benzoguanamine.

8. A molded article obtained by molding the polyacetal resin composition according to claim 1 or 2.

Images