Fiber-reinforced polyamide resin composition, molded body, sliding member, gear, worm wheel, and method for producing thermoplastic resin composition

Abstract

To provide a method for producing a thermoplastic resin composition capable of improving vibration fatigue resistance and suppressing discoloration.SOLUTION: Adding 5 parts by mass or more and 100 parts by mass or less of glass fibers having an average fiber diameter of 3 μm or more and 15 μm or less to 100 parts by mass of a thermoplastic resin having a viscosity number RV of 25 or more and 70 or less; A method for producing a thermoplastic resin composition, comprising a melt-kneading step of melt-kneading to obtain a melt-kneaded product, and a heating step of heating the melt-kneaded product at a temperature T represented by the following general formula (I) to obtain a thermoplastic resin composition, wherein the melt-kneaded product is an elliptic cylindrical pellet, a ratio a / b of a major axis a to a minor axis b in a cross section of the elliptic cylindrical pellet is 1.3 to 3.0, and in the heating step, the elliptic cylindrical pellet is heated while stirring. (I): Tm-130 °C ≤ T ≤ Tm-10 °C wherein Tm is the melting point of the thermoplastic resin. ) SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a fiber-reinforced polyamide resin composition having excellent wear resistance and mechanical properties, and a molded article made from the same. More specifically, the present invention relates to a fiber-reinforced polyamide resin composition containing a polyamide having a specific viscosity and glass fibers of a specific composition, and a molded article, a sliding member, a gear, and a worm wheel made from the same. The present invention also relates to a method for producing a thermoplastic resin composition. This application claims priority based on Japanese Patent Application No. 2022-113784 filed in Japan on July 15, 2022, Japanese Patent Application No. 2022-122261 filed in Japan on July 29, 2022, and Japanese Patent Application No. 2022-165824 filed in Japan on October 14, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Polyamide resins have been widely used as materials for various parts in industrial materials, automobiles, electrical and electronic equipment, industrial applications, etc., due to their excellent sliding properties, moldability, mechanical properties, and chemical resistance. In particular, polyamide resins are often used for sliding components such as automotive gears and worms due to their excellent sliding properties and mechanical characteristics.

[0003] In order to improve these performances, studies have been conducted on compositions in which the viscosity is increased compared to ordinary polyamides, or in which the polyamides are combined with inorganic fillers such as glass fibers, glass flakes, alumina fibers, and layered inorganic compounds. Among these, glass fiber reinforced polyamide resin compositions containing high molecular weight polyamide and using glass fiber as an inorganic compound filler have attracted particular attention because of their high effectiveness in improving sliding properties and mechanical properties.

[0004] On the other hand, due to the need to reduce the weight of automobiles from an environmental perspective, there is also a demand for miniaturization of sliding components such as automotive gears and worms, etc. Accordingly, there is a demand for high durability of the sliding component materials themselves and reduction of variability in the physical properties of small components.

[0005] Regarding glass fiber-reinforced polyamide resin compositions containing high-molecular-weight polyamide compositions, for example, Patent Documents 1 and 2 disclose compositions that can improve sliding properties, mechanical properties, and productivity by blending specific glass fibers and coupling agents.

[0006] On the other hand, in recent years, there has been an increasing demand for resin compositions having resin components with higher molecular weights in order to improve the performance of various machines and parts. Known methods for obtaining a high molecular weight resin composition include melt-kneading a high molecular weight resin in an extruder, and melt-kneading a low molecular weight resin in an extruder to obtain a pellet-like product, followed by a heating step (hereinafter sometimes referred to as solid-state polymerization) to increase the molecular weight.

[0007] Patent Document 3 describes a method for continuous solid-state polymerization of nylon 66, in which nylon 66 chips, which have been crystallized so that the crystallinity of the chip surface is 11% or more, are allowed to flow downward in a layer while being heated to 150 to 200°C by an inert gas supplied countercurrently from below to cause solid-state polymerization.

[0008] Patent Document 4 describes a method for producing polyamide resin chips, which includes a solid-state polymerization process in which raw polyamide resin chips are piled up and moved by free fall, and an inert gas is passed countercurrently to the movement of the raw polyamide resin chips, followed by a process in which the polyamide resin chips are cooled under inert gas in a cooling zone, during which the dew point of the inert gas is corrected to maintain the moisture content of the polyamide resin chips within a predetermined range.

[0009] Patent Document 5 describes reinforced polyamide resin pellets containing a polyamide resin having a melting point of 200 to 270°C and at least one inorganic filler selected from the group consisting of chopped strand glass fiber, carbon fiber, wollastonite, talc, mica, kaolin, barium sulfate, calcium carbonate, apatite, sodium phosphate, fluorite, silicon nitride, potassium titanate, and molybdenum disulfide, and having a cross-sectional major axis / minor axis ratio (major axis / minor axis) of 1.3 to 2.5.

[0010] Patent Document 6 describes a resin composition pellet containing a thermoplastic resin and a desiccant, having an elliptical cylindrical shape, in which the ratio of the minor axis to the major axis of the elliptical surface of the pellet (minor axis / major axis) is 0.5 to 0.9.

[0011] Alternatively, various fillers have been incorporated into polyamide resins to improve the mechanical properties of molded polyamide resin products or the molding properties of polyamide resins, such as tetrafluoroethylene resin particles as a lubricant and glass fiber as a reinforcing material.

[0012] Patent Document 7 describes a polyamide resin composition suitable for molding sliding components, which has low friction and excellent wear resistance and is obtained by blending polytetrafluoroethylene particles with a polyamide resin such as nylon 46, and, as necessary, calcium titanate whiskers, glass fibers, or the like.

[0013] Patent Document 8 describes a resin composition for sliding materials, which is obtained by blending glass fiber, tetrafluoroethylene resin, and molybdenum disulfide with a polyamide resin, typically 66-nylon (66-polyamide resin).

[0014] Patent Document 9 describes a resin composition in which 15% by mass to 30% by mass of reinforcing fibers such as small-diameter glass fibers having a fiber diameter of approximately 6 μm to 8 μm are blended with a thermoplastic resin such as nylon MXD6 or nylon 66. This resin composition is described as being particularly suitable for producing hollow tubes with excellent inner surface smoothness.

[0015] Patent Document 10 describes a reduction gear for an electric power steering device molded using a polyamide resin mixture. Patent Document 4 discloses blending a fibrous material such as glass fiber or carbon fiber into a polyamide resin mixture.

[0016] Patent Document 11 discloses the results of investigating various physical properties, primarily the abrasion resistance, frictional properties, and critical PV value, of molded articles of known glass fiber-containing polyamide resin compositions. Specifically, it reports that particularly excellent abrasion resistance, frictional properties, and critical PV value are achieved when a polyamide resin composition containing polyamide 66 having a number average molecular weight within a specific range as a polyamide resin, glass fibers having a specific average fiber diameter and average fiber length that are bundled using a specific sizing agent, and specific additives is molded. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Japanese Patent Application Publication No. 2018-197316 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-117817 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-198841 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-69515 [Patent Document 5] Japanese Patent Application Laid-Open No. 2016-14154 [Patent Document 6] International Publication No. 2017 / 111055 [Patent Document 7] Japanese Patent Application Publication No. 185747 / 1983 [Patent Document 8] Japanese Unexamined Patent Publication No. 1-110558 [Patent Document 9] Japanese Patent Application Publication No. 8-41246 [Patent Document 10] Japanese Patent Application Laid-Open No. 2003-83423 [Patent Document 11] Patent No. 4321590 Summary of the Invention [Problem to be solved by the invention]

[0018] However, Patent Documents 1 and 2 do not achieve sufficient mechanical properties, reduced property variation, and sliding properties in polyamides in the high molecular weight range having a formic acid relative viscosity of 90 or more, and further improvements are desired.

[0019] Patent Documents 3 and 4 are technologies relating to a solid-state polymerization method for chips (pellets), while Patent Documents 5 and 6 are technologies relating to pellet shapes. Therefore, no study has yet been conducted on the pellet shapes used in the solid-state polymerization of thermoplastic resins such as polyamide resins.

[0020] On the other hand, in general, in the case of resins that are not reinforced with fillers, the vibration fatigue characteristics are determined by the entanglement of polymer chains, so that higher molecular weight resins have better vibration fatigue resistance. In contrast, in the case of resins reinforced with fillers, the interface between the filler and the resin can be the starting point for vibration fatigue failure, and the lower the degree of adhesion at the interface between the filler and the resin, the lower the vibration fatigue resistance.

[0021] Therefore, the polyamide resin compositions described in Patent Documents 7 to 11 have a problem that, although they have a sufficiently high molecular weight, they contain a filler and therefore do not have sufficient vibration fatigue resistance in particular.

[0022] Furthermore, polyamide resins are prone to yellowing due to thermal oxidative degradation, which discolors the resin pellets, resulting in poor color and transparency in the resulting molded resin products, reducing their commercial value. For this reason, there is a strong demand for products with excellent color quality.

[0023] The present invention has been made in view of the above problems, and aims to provide a fiber-reinforced polyamide resin composition that is endowed with sufficient mechanical properties, has reduced variations in properties, and has improved sliding properties, and a molded article, sliding member, gear, and worm wheel that use the same. Another object of the present invention is to provide a method for producing a thermoplastic resin composition that has improved mechanical properties, long-term properties, and productivity. Another object of the present invention is to provide a method for producing a thermoplastic resin composition that can improve vibration fatigue resistance and suppress coloration. [Means for solving the problem]

[0024] The present invention includes the following aspects. [1] A fiber-reinforced polyamide resin composition containing a crystalline polyamide (A1) and glass fibers (B1), wherein the fiber-reinforced polyamide resin composition has a formic acid relative viscosity of 90 or more, an insoluble content when the fiber-reinforced polyamide resin composition is dissolved in formic acid is 105 mass% or more relative to the ash content of the fiber-reinforced polyamide resin composition, and the glass fibers (B1) contained in the fiber-reinforced polyamide resin composition contain glass fibers having a fiber length of 250 μm or less in a proportion of 55% or less. [2] The fiber-reinforced polyamide resin composition according to [1], wherein the number average fiber diameter of the glass fibers is 5 μm or more and 9 μm or less. [3] The fiber-reinforced polyamide resin composition according to [1] or [2], comprising 1 part by mass or more and 100 parts by mass or less of the glass fiber (B1) per 100 parts by mass of the crystalline polyamide (A1). [4] The fiber-reinforced polyamide resin composition according to any one of [1] to [3], which has a formic acid relative viscosity of 130 or more. [5] A molded article obtained by molding the fiber-reinforced polyamide resin composition according to any one of [1] to [4]. [6] A sliding member made of the fiber-reinforced polyamide resin composition according to any one of [1] to [4]. [7] The sliding member according to [6], wherein the coefficient of variation of tensile strength measured in accordance with ISO 527 is 1.0 or less. [8] A gear made of the fiber-reinforced polyamide resin composition according to any one of [1] to [4]. [9] A worm wheel made of the fiber-reinforced polyamide resin composition according to any one of [1] to [4].

[0025]

[10] A melt-kneading process in which 5 parts by mass or more and 100 parts by mass or less of glass fibers having an average fiber diameter of 3 μm or more and 15 μm or less are added to 100 parts by mass of a thermoplastic resin having a viscosity number RV of 25 or more and 70 or less, and the mixture is melt-kneaded to obtain a melt-kneaded product; and a heating step of heating the melt-kneaded product at a temperature T represented by the following general formula (I) to obtain a thermoplastic resin composition, The melt-kneaded product is an elliptical cylindrical pellet, and the ratio a / b of the major axis a to the minor axis b in the cross section of the elliptical cylindrical pellet is 1.3 to 3.0; The method for producing a thermoplastic resin composition, wherein the heating step comprises heating the elliptical cylindrical pellets while stirring them. Tm-130℃≦T≦Tm-10℃ (I) (In the formula, Tm is the melting point of the thermoplastic resin.)

[11] The method for producing a thermoplastic resin composition according to

[10] , characterized in that the viscosity number RV of the thermoplastic resin is 70 or more and 400 or less.

[12] The method for producing a thermoplastic resin composition according to

[10] or

[11] , characterized in that the heating step is performed at the temperature T for 30 minutes or more and 15 hours or less.

[13] The method for producing a thermoplastic resin composition according to any one of

[10] to

[12] above, wherein the thermoplastic resin is polyamide or polyester.

[14] The method for producing a thermoplastic resin composition according to

[13] , wherein the polyamide is at least one selected from the group consisting of polyamide 6, polyamide 66, polyamide 46, polyamide 610, and polyamide 612.

[15] The method for producing a thermoplastic resin composition according to any one of

[10] to

[14] , wherein the heating step is performed at the temperature T in an inert gas atmosphere having an oxygen concentration of 5 ppm or less.

[16] The method for producing a thermoplastic resin composition according to any one of

[10] to

[15] , wherein the heating step is performed at the temperature T in an inert gas atmosphere having a moisture concentration of 10 ppm or less.

[0026]

[17] A melt-kneading process in which 5 parts by mass or more and 100 parts by mass or less of glass fibers having an average fiber diameter of 3 μm or more and 9 μm or less are added to 100 parts by mass of a thermoplastic resin having a viscosity number VN of 80 or more and 200 or less, and the mixture is melt-kneaded to obtain a melt-kneaded product; a heating step of heating the melt-kneaded product at a temperature T represented by the following mathematical formula (I) to obtain a thermoplastic resin composition, A method for producing a thermoplastic resin composition, wherein the heating step contains 0.05 to 1.0 mass % of water relative to 100 mass % of the melt-kneaded product obtained by the melt-kneading. Tm-130℃≦T≦Tm-10℃ (I) (In the formula, Tm is the melting point of the thermoplastic resin.)

[18] The method for producing a thermoplastic resin composition according to

[17] , wherein the thermoplastic resin composition has a viscosity number VN of 200 or more and 350 or less.

[19] The method for producing a thermoplastic resin composition according to

[17] or

[18] , wherein the average fiber length of the glass fibers contained in the thermoplastic resin composition after the heating step is 100 μm or more and 1000 μm or less.

[20] The method for producing a thermoplastic resin composition according to any one of

[17] to

[19] , wherein the glass fibers have an average fiber diameter of 4 μm or more and 8 μm or less.

[21] The method for producing a thermoplastic resin composition according to any one of

[17] to

[20] , wherein in the heating step, heating at the temperature T is carried out for 30 minutes or more and 15 hours or less.

[22] The method for producing a thermoplastic resin composition according to any one of

[17] to

[21] , wherein in the heating step, heating at the temperature T is carried out in an inert gas atmosphere having an oxygen concentration of 5 ppm or less.

[23] The method for producing a thermoplastic resin composition according to any one of

[17] to

[22] , wherein the thermoplastic resin is polyamide or polyester.

[24] The method for producing a thermoplastic resin composition according to

[23] , wherein the polyamide is polyamide 6, polyamide 66, or polyamide 610.

[25] The method for producing a thermoplastic resin composition according to any one of

[17] to

[24] , wherein the thermoplastic resin composition is substantially free of boron oxide. [Effects of the Invention]

[0027] According to the present invention, it is possible to obtain a fiber-reinforced polyamide resin composition that has been imparted with sufficient mechanical properties, reduced variations in properties, and imparted with sliding properties, as well as a molded article, a sliding member, a gear, and a worm wheel that use the same. According to the present invention, it is possible to provide a method for producing a thermoplastic resin composition that has improved mechanical properties, long-term properties, and productivity. According to the present invention, it is possible to produce a thermoplastic resin composition that has improved vibration fatigue resistance and is capable of suppressing coloration. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the present invention.

[0029] <Fiber-reinforced polyamide resin composition> The fiber-reinforced polyamide resin composition according to the first embodiment of the present invention contains a crystalline polyamide (A1) and glass fibers (B1). Hereinafter, the term "fiber-reinforced polyamide resin composition" may be abbreviated as "polyamide composition."

[0030] The fiber-reinforced polyamide resin composition has a formic acid relative viscosity VR of not less than 90. When the formic acid relative viscosity is not less than 90, a fiber-reinforced polyamide resin molded article having more excellent mechanical properties and sliding properties tends to be obtained.

[0031] The formic acid relative viscosity VR of the fiber-reinforced polyamide resin composition is preferably 110 or more, and more preferably 130 or more.

[0032] The formic acid relative viscosity can be measured by the method according to ASTM D789 shown in the Examples. More specifically, the formic acid relative viscosity VR is measured at 25°C using a solution prepared by dissolving the soluble matter in the fiber-reinforced polyamide resin composition in 90% by mass of formic acid (10% by mass of water) in a proportion of 8.4% by mass.

[0033] The fiber-reinforced polyamide resin composition of the present embodiment is characterized in that when the fiber-reinforced polyamide resin composition is dissolved in formic acid, the insoluble content is 105 mass% or more relative to the ash content of the fiber-reinforced polyamide resin composition. In the present specification, the ash content of the fiber-reinforced polyamide resin composition can also be regarded as the amount of glass fiber charged, and is calculated, for example, as the ash content based on the specification of ISO3451-4. When the fiber-reinforced polyamide resin composition is dissolved in formic acid, the insoluble content is 105 mass% or more relative to the ash content (amount of glass fiber charged) of the fiber-reinforced polyamide resin composition, so that a fiber-reinforced polyamide resin molding having excellent mechanical properties and sliding characteristics can be obtained. Specifically, the formic acid-insoluble content relative to the ash content (amount of glass fiber charged) of the fiber-reinforced polyamide resin composition can be measured by the following method: The fiber-reinforced polyamide resin composition is placed in 90% by mass formic acid (10% by mass water), and the solution obtained by dissolving the composition under stirring for one day is filtered using a membrane filter with a pore size of 0.65 μm to separate the formic acid-insoluble content remaining on the filter paper. The separated formic acid-insoluble content is air-dried for one day to remove residual solvent, and the mass of the resulting dried product is measured to determine the amount of formic acid-insoluble content according to the following formula: Formic acid insoluble matter (mass%) = dry mass (g) / fiber-reinforced polyamide resin composition dissolved in formic acid (g) × 100 Furthermore, the ash content of the sample is measured in advance, for example, based on the provisions of ISO3451-4, and the amount of formic acid insoluble matter relative to the ash content (amount of glass fiber charged) is calculated using the following formula. Formic acid insoluble content (mass %) relative to ash content = formic acid insoluble content (mass %) / ash content (mass %) × 100

[0034] By satisfying the specific composition, the fiber-reinforced polyamide resin composition of the present embodiment can impart sufficient mechanical properties to the resulting molded article, reduce variations in properties, and further impart sliding properties to the molded article.

[0035] Hereinafter, each component of the fiber-reinforced polyamide resin composition according to this embodiment will be described in detail.

[0036] <Component (A1): Crystalline polyamide> In this specification, the term "crystalline polyamide" refers to a polyamide having a crystalline heat of fusion of 4 J / g or more when measured at 20° C. / min by a differential scanning calorimeter.

[0037] The terminal amino group concentration [NH2] of the crystalline polyamide contained in the fiber-reinforced polyamide resin composition is preferably 1 meq / kg to 100 meq / kg, more preferably 3 meq / kg to 90 meq / kg, and even more preferably 5 meq / kg to 80 meq / kg. When the terminal amino group concentration is within the above range, the color tone of the polyamide resin composition tends to be excellent and yellowing due to deterioration tends to be further suppressed.

[0038] The terminal amino group concentration can be measured by dissolving a predetermined amount of polyamide sample in a 90% by volume aqueous phenol solution, and titrating the solution with 1 / 50 N hydrochloric acid at 25°C.

[0039] The terminal carboxyl group concentration [COOH] of the crystalline polyamide contained in the fiber-reinforced polyamide resin composition is preferably 10 to 150 milliequivalents / kg, more preferably 20 to 140 milliequivalents / kg, and even more preferably 30 to 130 milliequivalents / kg. When the terminal carboxyl group concentration is within the above range, the appearance of a molded article of the fiber-reinforced polyamide resin composition tends to be more excellent.

[0040] The terminal carboxyl group concentration can be measured by dissolving a predetermined amount of polyamide sample in benzyl alcohol at 160°C and titrating it with a 1 / 10 N solution of potassium hydroxide in ethylene glycol using phenolphthalein as an indicator.

[0041] The terminal carboxyl group to terminal amino group ratio (terminal carboxyl group / terminal amino group) of the crystalline polyamide contained in the fiber-reinforced polyamide resin composition is 0.1 or more, preferably 0.5 or more, and more preferably 1 or more. The upper limit of the ratio (terminal carboxyl group / terminal amino group) is, for example, 20 or less, 15 or less, or 10 or less. The upper and lower limits of the ratio (terminal carboxyl groups / terminal amino groups) can be combined in any combination, such as 0.1 to 20, 0.5 to 15, or 1 to 10.

[0042] When the ratio (terminal carboxyl group / terminal amino group) is within the above range, a molded article having excellent fatigue properties and gear durability is likely to be obtained.

[0043] Here, the ratio of terminal carboxyl groups to terminal amino groups refers to a value obtained by dividing the terminal carboxyl group concentration [COOH] by the terminal amino group concentration [NH2].

[0044] Examples of crystalline polyamides include, but are not limited to, (A1-a) polyamides obtained by ring-opening polymerization of lactams, (A1-b) polyamides obtained by self-condensation of ω-aminocarboxylic acids, (A1-c) polyamides obtained by condensing diamines and dicarboxylic acids, and copolymers thereof. The crystalline polyamides may be used singly or in combination of two or more.

[0045] Examples of lactams used in the production of polyamide (A1-a) include, but are not limited to, pyrrolidone, caprolactam, undecalactam, and dodecalactam.

[0046] The ω-aminocarboxylic acid used in the production of the (A1-b) polyamide is not limited to the following, but examples thereof include ω-amino fatty acids, which are ring-opened compounds of the above lactams with water. Furthermore, two or more kinds of the lactam or ω-aminocarboxylic acid may be used in combination and condensed.

[0047] (A1-c) Examples of diamines (monomers) used in the production of polyamides include, but are not limited to, linear aliphatic diamines, branched aliphatic diamines, alicyclic diamines, and aromatic diamines.

[0048] Examples of the linear aliphatic diamine include, but are not limited to, hexamethylenediamine and pentamethylenediamine.

[0049] Examples of branched aliphatic diamines include, but are not limited to, 2-methylpentanediamine and 2-ethylhexamethylenediamine.

[0050] Examples of alicyclic diamines include, but are not limited to, cyclohexanediamine, cyclopentanediamine, and cyclooctanediamine.

[0051] Examples of aromatic diamines include, but are not limited to, p-phenylenediamine and m-phenylenediamine.

[0052] The dicarboxylic acid (monomer) used in the production of the polyamide (A1-c) is not limited to the following, but examples thereof include aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids.

[0053] Examples of the aliphatic dicarboxylic acid include, but are not limited to, adipic acid, pimelic acid, and sebacic acid.

[0054] The alicyclic dicarboxylic acid is not limited to the following, but examples thereof include cyclohexanedicarboxylic acid.

[0055] Examples of aromatic dicarboxylic acids include, but are not limited to, phthalic acid and isophthalic acid.

[0056] The diamine and dicarboxylic acid as the monomers may be condensed either individually or in combination of two or more.

[0057] The crystalline polyamide may further contain, as necessary, units derived from a trivalent or higher polycarboxylic acid such as trimellitic acid, trimesic acid, pyromellitic acid, etc. The trivalent or higher polycarboxylic acid may be used alone or in combination of two or more.

[0058] Specific examples of the crystalline polyamide contained in the fiber-reinforced polyamide resin composition of this embodiment include polyamide 4 (poly-α-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecaneamide), polyamide 12 (polydodecanamide), polyamide 46 (polytetramethylene adipamide), polyamide 56 (polypentamethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodecamide), polyamide 6T (polyhexamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), and copolymer polyamides containing these as constituent components.

[0059] Among these, polyamide 66 (PA66), polyamide 46 (PA46), or polyamide 610 (PA610) is preferred as the crystalline polyamide from the viewpoint of sliding properties. PA66 is particularly preferred because it is a suitable material for automobile parts due to its excellent heat resistance, moldability, and toughness.

[0060] Polyamide polymerization methods include, but are not limited to, thermal melt polycondensation, solid-state polymerization, and solution polymerization. Thermal melt polycondensation involves, for example, blending hexamethylene adipamide, a raw material for polyamide 66, with an antifoaming agent, if necessary, and then heating and concentrating the mixture at a temperature of 40 to 300°C. The generated water vapor pressure is maintained at a pressure between atmospheric pressure and 20 atmospheres, and finally releasing the pressure to atmospheric pressure or reduced pressure to carry out polycondensation. Solid-state polymerization is a method of polymerization at a temperature below the melting point of the diamine or dicarboxylate solid salt or polycondensate. Furthermore, the solution method involves polycondensing a dicarboxylic acid halide component and a diamine component in a solution. These methods may be combined as needed. The polymerization method may be a batch or continuous method. The polymerization apparatus is also not particularly limited, and examples include autoclave reactors, tumbler reactors, and extruder reactors such as kneaders.

[0061] To obtain a polyamide having a predetermined formic acid relative viscosity VR, any common method can be used, and is not particularly limited, such as a method of adjusting the polymerization time in the above-mentioned hot melt polycondensation method or a method of performing solid-phase polymerization at a temperature below the melting point of the polycondensate.

[0062] <(B1) Component: Glass fiber> The fiber-reinforced polyamide resin composition of the present embodiment contains glass fibers (B1). The glass fibers (B1) contained in the polyamide resin composition have a ratio of glass fibers having a fiber length of 250 μm or less of 55% by number. The glass fibers (B1) having a fiber length of 250 μm or less may be referred to as "short GF." The glass fibers (B1) contained in the polyamide resin composition preferably have a number average fiber length of 300 μm or more, more preferably 350 μm or more.

[0063] The proportion of short glass fibers in all glass fibers (B1) contained in a polyamide resin composition and the number average fiber length of the glass fibers (B1) are specifically measured by the following method: After removing only the polyamide of the polyamide composition by burning or dissolving, the polyamide is observed using an optical microscope, and the lengths of 400 arbitrarily selected reinforcing fibers are measured using an image analyzer, and the proportion of glass fibers 250 μm or less and the number average fiber length are calculated.

[0064] The proportion of short glass fibers in all glass fibers contained in the polyamide resin composition is preferably 55% or less, more preferably 50% or less, and even more preferably 45% or less.

[0065] The glass fibers are preferably at least partially coated with a surface treatment agent. The fiber-reinforced polyamide resin composition contains glass fibers at least partially coated with a surface treatment agent, which allows the glass fibers to be defibrillated and processed easily in the fiber-reinforced polyamide resin composition.

[0066] The average fiber diameter of the glass fibers is not particularly limited, but is preferably 4 to 30 μm, more preferably 5 to 15 μm, more preferably 5 to 9 μm, and particularly preferably 5 to 8 μm. Here, the average fiber diameter is a number-based value observed with an electron microscope or the like. When the average fiber diameter is within the above range, the polyamide resin composition tends to be imparted with better mechanical strength, rigidity, and moldability, and to achieve reduced variations in mechanical properties. As the glass fiber, any commercially available glass fiber such as chopped glass, roving glass, milled glass, etc. can be used.

[0067] The surface treatment agent for glass fibers may also contain a sizing agent, and examples thereof include, but are not limited to, urethane resins, polycarbodiimide compounds, homopolymers of acrylic acid, copolymers of acrylic acid and copolymerizable monomers, salts of homopolymers (homopolymers of acrylic acid) or copolymers (copolymers of acrylic acid and copolymerizable monomers) with amines, epoxy resins, and copolymers of carboxylic acid anhydride-containing unsaturated vinyl monomers and unsaturated vinyl monomers. These may be used alone or in combination of two or more.

[0068] The urethane resin is not particularly limited as long as it is one that is commonly used as a surface treatment agent or sizing agent for glass fibers. For example, a resin synthesized from an isocyanate such as m-xylylene diisocyanate (XDI), 4,4'-methylenebis(cyclohexyl isocyanate) (HMDI) or isophorone diisocyanate (IPDI) and a polyester or polyether diol can be suitably used.

[0069] The polycarbodiimide compound is not particularly limited, but examples thereof include those obtained by condensing a compound containing one or more carbodiimide groups (-N=C=N-).

[0070] The weight-average molecular weight of the acrylic acid homopolymer is preferably 1,000 to 90,000, more preferably 1,000 to 50,000, and even more preferably 1,000 to 25,000. The weight-average molecular weight in this specification can be determined by measurement using GPC (gel permeation chromatography).

[0071] The copolymerizable monomer constituting the copolymer of acrylic acid and a copolymerizable monomer is not particularly limited, but examples thereof include monomers having a hydroxyl group and / or a carboxyl group, and ester-based monomers. Such copolymerizable monomers are not particularly limited, but examples thereof include one or more selected from the group consisting of acrylic acid, maleic acid, methacrylic acid, vinylacetic acid, crotonic acid, isocrotonic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, and ester compounds thereof (excluding the case where only acrylic acid is used). Among the above-mentioned monomers, it is preferable to have one or more ester-based monomers.

[0072] The amine that forms a salt with the homopolymer or copolymer of acrylic acid is not particularly limited and may be a primary, secondary, or tertiary amine, but specific examples include triethylamine, triethanolamine, and glycine. The degree of neutralization is preferably 20 to 90%, more preferably 30 to 80%, and even more preferably 40 to 60%, from the viewpoint of improving the stability of a mixed solution with other concomitant agents (such as a silane coupling agent) and reducing the amine odor.

[0073] The weight-average molecular weight of the acrylic acid homopolymer or copolymer forming the salt is not particularly limited, but is preferably 3,000 to 50,000. When the weight-average molecular weight is 3,000 or more, the bundling ability of the glass fibers tends to be further improved. Furthermore, when the weight-average molecular weight is 50,000 or less, the mechanical properties of the resulting molded article tend to be further improved.

[0074] The epoxy resin is not particularly limited, but for example, it is preferable to use a compound having at least two glycidyl groups, and among them, an epoxy resin obtained by reacting bisphenol with epihalohydrin is suitable. In addition, in consideration of the bundling property of the glass fiber, the epoxy equivalent of the epoxy resin is preferably 180 g / equivalent or more, more preferably 450 to 1900 g / equivalent.

[0075] In the glass fiber-reinforced polyamide resin composition of the present embodiment, the surface treatment agent or sizing agent for the glass fibers preferably contains a copolymer of a carboxylic acid anhydride-containing unsaturated vinyl monomer and an unsaturated vinyl monomer, because the resulting molded article tends to have better mechanical properties. The carboxylic acid anhydride-containing unsaturated vinyl monomer is not particularly limited, but examples thereof include maleic anhydride, itaconic anhydride, and citraconic anhydride, with maleic anhydride being preferred. On the other hand, the unsaturated vinyl monomer is not particularly limited, but examples thereof include styrene, α-methylstyrene, ethylene, propylene, butadiene, isoprene, chloroprene, 2,3-dichlorobutadiene, 1,3-pentadiene, cyclooctadiene, methyl methacrylate, methyl acrylate, ethyl acrylate, and ethyl methacrylate, of which ethylene, styrene, and butadiene are preferred.

[0076] Among the combinations of carboxylic acid anhydride-containing unsaturated vinyl monomers and unsaturated vinyl monomers, copolymers of maleic anhydride and butadiene, copolymers of maleic anhydride and ethylene, copolymers of maleic anhydride and styrene, and mixtures thereof are more preferred.

[0077] The weight-average molecular weight of the copolymer containing the carboxylic acid anhydride-containing unsaturated vinyl monomer and the unsaturated vinyl monomer is preferably 2,000 or more, more preferably 2,000 to 1,000,000, and even more preferably 5,000 to 500,000. When the weight-average molecular weight is within the above range, the flowability of the glass fiber-reinforced polyamide resin composition tends to be further improved.

[0078] It is also suitable to use a silane coupling agent as a surface treatment agent for glass fibers. The silane coupling agent is not particularly limited, but examples thereof include aminosilanes such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; mercaptosilanes such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane; epoxysilanes; and vinylsilanes. Among these, it is preferable to use one or more selected from the above-listed components, and aminosilanes are more preferable.

[0079] It is preferable to use a lubricant when preparing the surface treatment agent for glass fibers. The lubricant is not particularly limited, but any ordinary liquid or solid lubricant material suitable for the purpose can be used. Examples of such lubricants include, but are not limited to, animal, vegetable, or mineral waxes such as carnauba wax and lanolin wax; and surfactants such as fatty acid amides, fatty acid esters, fatty acid ethers, or aromatic esters or aromatic ethers.

[0080] (Method for coating glass fiber surface with surface treatment agent) In this embodiment, the glass fiber is preferably one in which at least a portion of the surface is coated with a surface treatment agent. The method for coating the surface treatment agent is not particularly limited, but for example, in a known glass fiber manufacturing process, the surface treatment agent is applied to the glass fiber using a known method such as a roller-type applicator to produce a glass fiber strand, and the produced glass fiber strand is dried to allow a continuous reaction to occur.

[0081] The state of the glass fiber is not particularly limited, but for example, the glass fiber strand may be used as a roving as it is, or may be further cut into chopped glass strands. The strands may be dried after the cutting step, or may be cut after drying.

[0082] The amount of the surface treatment agent attached to the glass fibers is preferably 0.1 to 1.0 part by mass, more preferably 0.2 to 1.0 part by mass, still more preferably 0.2 to 0.8 parts by mass, and most preferably 0.2 to 0.6 parts by mass, in terms of solid content, per 100 parts by mass of the glass fibers. When the amount of the surface treatment agent attached to the glass fibers is 0.1 part by mass or more, in terms of solid content, per 100 parts by mass of the glass fibers, the coating of the surface treatment agent on the glass fibers tends to be more maintained. On the other hand, when the amount used is 1.0 part by mass or less, in terms of solid content, per 100 parts by mass of the glass fibers, the thermal stability of the fiber-reinforced polyamide resin composition tends to be further improved.

[0083] The polyamide resin composition of the present embodiment preferably contains 1 part by mass or more and 100 parts by mass or less, and more preferably 15 parts by mass or more and 50 parts by mass or less, of glass fiber (B1) per 100 parts by mass of crystalline polyamide (A1).

[0084] ≪(C1) component: copper compound≫ A copper compound is preferably added to the polyamide resin composition. The copper compound may be referred to as "component (C1)." Examples of component (C1) include, but are not limited to, copper halides, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, copper salicylate, copper nicotinate, copper stearate, and copper complex salts coordinated with chelating agents such as ethylenediamine and ethylenediaminetetraacetic acid. These copper compounds may be used alone or in combination. Among these, copper halides are preferred, and copper iodide, copper (I) bromide, copper (II) bromide, copper (I) chloride, and copper acetate are preferred from the viewpoints of suppressing molecular weight reduction during melt-kneading and / or improving heat aging resistance, with copper iodide being more preferred.

[0085] <Component (D1): Alkali Metal and / or Alkaline Earth Metal Halide> The polyamide resin composition preferably contains either or both of an alkali metal halide and an alkaline earth metal halide, which may be referred to as "component (D1)."

[0086] Examples of component (D1) include, but are not limited to, potassium iodide, potassium bromide, potassium chloride, sodium iodide, sodium chloride, and mixtures thereof. These may be used alone or in combination of two or more.

[0087] As the component (D1), only an alkali metal halide may be used, only an alkaline earth metal halide may be used, or both an alkali metal halide and an alkaline earth metal halide may be used. Among these, from the viewpoint of improving heat aging resistance and suppressing metal corrosion, potassium iodide and / or potassium bromide are preferred, and potassium iodide is more preferred.

[0088] The combined use of components (C1) and (D1) is preferable from the viewpoints of not only achieving better thermal stability but also suppressing variations in mechanical properties and improving wear properties. When used in combination, components (C1) and (D1) are preferably contained in the polyamide resin composition in such a ratio that the molar ratio of the halogen content to the copper content (halogen / copper) is 3 / 1 to 50 / 1.

[0089] The molar ratio of the halogen content to the copper content (halogen / copper) is more preferably 4 / 1 to 40 / 1, and even more preferably 5 / 1 to 30 / 1. Here, "halogen" refers to "halogen elements" such as Br and I, and further, when a copper halide is used as component (C1), it refers to the sum of the halogen derived from the copper halide and the halogen derived from component (D1). A molar ratio of the halogen content to the copper content within the above range is preferable from the viewpoints of suppressing copper deposition and metal corrosion, suppressing variations in mechanical strength, and improving wear properties.

[0090] <Heat stabilizer> It is preferable to add a heat stabilizer to the polyamide resin composition. The heat stabilizer is not particularly limited, but examples thereof include phenol-based stabilizers such as hindered phenol compounds, phosphite-based stabilizers, hindered amine-based stabilizers, triazine-based stabilizers, and sulfur-based stabilizers. The heat stabilizers may be used alone or in combination of two or more. When a heat stabilizer is added, deterioration due to heat tends to be more effectively suppressed. In this embodiment, the content of the heat stabilizer is not particularly limited, but from the viewpoints of effectively suppressing thermal degradation, preventing coloration, and maintaining mechanical properties, it is preferably 0.005 to 5 parts by mass, more preferably 0.015 to 2 parts by mass, and even more preferably 0.03 to 0.1 parts by mass, relative to 100 parts by mass of the polyamide resin.

[0091] The phenolic stabilizer is a molecule containing a phenol group, and examples thereof include, but are not limited to, Irganox (registered trademark) 1098 (manufactured by BASF).

[0092] The phosphite stabilizer is a molecule containing phosphorus, and is not particularly limited, but an example thereof is PEP (registered trademark) 36 (manufactured by ADEKA Corporation).

[0093] <Other additives> If necessary, other additives may be added to the polyamide resin composition to the extent that the object of this embodiment is not impaired. The other additives are not particularly limited, but examples thereof include inorganic fillers other than glass fiber, antioxidants, ultraviolet absorbers, photodegradation inhibitors, plasticizers, lubricants, mold release agents, nucleating agents, flame retardants, and colorants, and other thermoplastic resins may also be added. Since the properties of the additives vary significantly, the preferred content of each component that does not substantially impair the effect of this embodiment varies, and each can be set appropriately.

[0094] <Method of producing fiber-reinforced polyamide resin composition> The method for producing the fiber-reinforced polyamide resin composition of the present embodiment is not particularly limited, and the composition can be produced by mixing and kneading (A1) crystalline polyamide, (B1) glass fiber, and other components that are blended as needed, in any order.

[0095] The fiber-reinforced polyamide resin composition is preferably melt-kneaded using various commonly used extruders such as single-screw or twin-screw extruders, with twin-screw extruders being particularly preferred in terms of productivity and versatility. Specifically, when chopped glass strands are used as the (B1) glass fibers, a twin-screw extruder equipped with an upstream feed port and a downstream feed port is preferably used, and the chopped glass strands are fed from the upstream feed port and melt-kneaded. When a high-molecular-weight polyamide is used, melt-kneading using a twin-screw extruder can sometimes result in a decrease in molecular weight. Therefore, a method is preferably used in which a low-molecular-weight polyamide and the (B1) glass fibers are melt-kneaded in advance, followed by solid-state polymerization at or below the melting point to obtain a high-molecular-weight fiber-reinforced polyamide resin composition. Furthermore, when glass rovings are used, they can be compounded using known methods.

[0096] <Molded article using fiber-reinforced polyamide resin composition> The molded article of the second embodiment of the present invention contains the fiber-reinforced polyamide resin composition according to the first embodiment. Although not particularly limited, for example, the molded article can be a molded article of various parts by injection molding the fiber-reinforced polyamide resin composition according to the above embodiment.

[0097] The molded article of this embodiment can be applied to, but is not particularly limited to, various parts for automobiles, machinery industry, electrical and electronics, industrial materials, industrial materials, daily necessities and household goods, etc. In this way, the molded article of this embodiment can impart sufficient mechanical properties, wear resistance, and low property variability to the various parts.

[0098] The physical properties that are the subject of low physical property variability include tensile strength, etc. The amount of variability that indicates variability includes relative amounts of variability such as the coefficient of variation, and absolute amounts of variability such as the standard deviation. In this specification, the coefficient of variation CV means the percentage of the standard deviation σ relative to the arithmetic mean μ, and is calculated by CV=(σ / μ)×100.

[0099] The molded article preferably has a coefficient of variation of tensile strength measured in accordance with ISO527 of 1.0 or less.

[0100] The fiber-reinforced polyamide resin composition according to the first embodiment of the present invention can be particularly suitably used for automotive parts, particularly sliding members such as automotive gears, worms, and worm wheels, due to its excellent mechanical properties, wear properties, and low variability in physical properties.

[0101] <Method of producing thermoplastic resin composition> The method for producing a thermoplastic resin composition according to the third embodiment of the present invention includes a melt-kneading step and a heating step. Descriptions of the same components as those in the first or second embodiment may be omitted.

[0102] The melt-kneading step is a step of adding 5 parts by mass or more and 100 parts by mass or less of glass fibers having a number average fiber diameter of 3 μm or more and 15 μm or less to 100 parts by mass of a thermoplastic resin having a viscosity number RV of 25 or more and 70 or less, and melt-kneading the mixture to obtain a melt-kneaded product. The heating step (hereinafter sometimes referred to as "solid-state polymerization") is a step in which the elliptical cylindrical pellets of the melt-kneaded product are heated at a temperature T represented by the following general formula (I) to obtain a thermoplastic resin composition. Tm-130℃≦T≦Tm-10℃ (I) (In the formula, Tm is the melting point of the thermoplastic resin.)

[0103] In the production method of the present embodiment, the melt-kneaded product is an elliptical cylindrical pellet having an elliptical cylindrical shape, and a ratio a / b of a major axis a to a minor axis b in a cross section of the elliptical cylindrical pellet is 1.3 to 3.0, In the heating step, the elliptical cylindrical pellets are heated while being stirred.

[0104] In conventional techniques, in order to obtain a thermoplastic resin composition having a high molecular weight, it has been common to polymerize a thermoplastic resin to increase its molecular weight, then add glass fibers and melt-knead the mixture. In the prior art, it was common practice to polymerize a thermoplastic resin to increase its molecular weight, then add glass fibers and melt-knead the mixture. In contrast, in the production method of this embodiment, the viscosity number RV is specified, a thermoplastic resin composition having a low to medium molecular weight is melt-kneaded with glass fiber, the molten mixture is extruded into a strand shape, and the extruded strand is passed through a water-cooled bath or the like to obtain pellets of a specific shape. When the pellets of a specific shape are solid-state polymerized, the high molecular weight component is selectively increased, thereby efficiently increasing the molecular weight. In addition, the time required for such solid-state polymerization can be shortened.

[0105] Each step of the manufacturing method of this embodiment will be described in detail below. (Melting and kneading process) In the melt-kneading step in the manufacturing method of this embodiment, glass fibers having a number average fiber diameter of 3 μm or more and 15 μm or less are added to a thermoplastic resin having a viscosity number RV of 25 or more and 70 or less in a specific blending ratio, and the resulting mixture is melt-kneaded to obtain a molten mixture. Specifically, the glass fibers may be added in an amount of 5 to 100 parts by mass, preferably 7 to 95 parts by mass, and more preferably 10 to 90 parts by mass, relative to 100 parts by mass of the thermoplastic resin. Alternatively, the glass fibers may be added in an amount of 11 to 100 parts by mass, 11 to 34 parts by mass, or 34 to 100 parts by mass, relative to 100 parts by mass of the thermoplastic resin. When the blending amount of the glass fiber is equal to or greater than the above-mentioned lower limit, a thermoplastic resin composition having increased rigidity and strength can be obtained. On the other hand, when the blending amount of the glass fiber is equal to or less than the above-mentioned upper limit, the resulting thermoplastic resin composition has better moldability when molded for each application.

[0106] Known melt-kneading devices can be used. For example, melt-kneading devices such as single-screw or twin-screw extruders, Banbury mixers, and mixing rolls can be used. Among these, multi-screw extruders equipped with a devolatilizing mechanism (vent) and a side feeder are preferred, and twin-screw extruders are more preferred.

[0107] When the thermoplastic resin and the glass fiber are melt-kneaded in the extruder, the molecular weight of the thermoplastic resin can be adjusted by appropriately setting the kneading conditions, such as the resin temperature during extrusion, the degree of vacuum, and the average residence time. The resin temperature during melt-kneading is preferably above the melting point of the raw thermoplastic resin but not exceeding 370°C, more preferably above 5°C above the melting point of the raw thermoplastic resin but not exceeding 350°C, even more preferably above 10°C above the melting point of the raw thermoplastic resin but not exceeding 340°C, particularly preferably above 15°C above the melting point of the raw thermoplastic resin but not exceeding 335°C, and most preferably above 20°C above the melting point of the raw thermoplastic resin but not exceeding 330°C. By maintaining the raw material (resin) temperature during melt-kneading above the melting point of the raw thermoplastic resin, the raw thermoplastic resin tends to be sufficiently melted, further reducing the load on the extruder motor. Furthermore, by maintaining the resin temperature during melt-kneading at 370°C or less, decomposition of the raw thermoplastic resin itself tends to be further suppressed. For example, when polyamide 66 having a melting point of 264° C. is used as the thermoplastic resin, the resin temperature during melt-kneading is preferably 264° C. or higher and 360° C. or lower, more preferably 270° C. or higher and 350° C. or lower, even more preferably 275° C. or higher and 340° C. or lower, particularly preferably 280° C. or higher and 335° C. or lower, and most preferably 285° C. or higher and 330° C. Note that even when a polyamide resin other than polyamide 66 is used as the raw polyamide resin, the temperature can be appropriately adjusted depending on its melting point.

[0108] The resin temperature during the melt-kneading can be measured, for example, by directly contacting a thermometer such as a thermocouple with the molten mixture discharged from the discharge port (spinning nozzle) of the extruder. The resin temperature during the melt-kneading can be adjusted by adjusting the heater temperature of the cylinder of the extruder or by appropriately adjusting the shear heat generation of the resin by changing the rotation speed and discharge rate of the extruder.

[0109] The average residence time during the melt-kneading is preferably 10 seconds or more and 120 seconds or less, more preferably 20 seconds or more and 100 seconds or less, even more preferably 25 seconds or more and 90 seconds or less, particularly preferably 30 seconds or more and 80 seconds or less, and most preferably 35 seconds or more and 70 seconds or less. By setting the average residence time during the melt-kneading to 10 seconds or more, a melt-kneaded product tends to be obtained more efficiently. Furthermore, by setting the average residence time during the melt-kneading to 120 seconds or less, the extrusion discharge rate (production rate) tends to increase to some extent. As a result, the productivity of the polyamide resin composition also tends to be improved. The average residence time refers to the residence time in the melt-kneading device when the residence time is constant, or the average of the shortest and longest residence times when the residence time is non-uniform. The average residence time can be measured by adding a component (hereinafter abbreviated as "component X") that can be distinguished from the raw polyamide resin used in the melt-kneading process, such as a colorant masterbatch during melt-kneading or a resin used in the melt-kneading process that has a different color from the raw polyamide resin, to the melt-kneading device, measuring the discharge start time and discharge end time when component X is at its most concentrated, and averaging the discharge start time and discharge end time. The average residence time can be adjusted appropriately by adjusting the discharge rate (discharge speed) and rotation speed of the extruder.

[0110] The melt-kneaded product (resin composition) obtained in the melt-kneading process is cooled to form elliptical cylindrical pellets. The shape of the elliptical cylindrical pellets can be obtained by adjusting the time for cooling the strands in a water-cooled bath or the like. For example, it is preferable to cool the strands to a water immersion length of 5 to 60 cm, more preferably about 10 to 45 cm, and even more preferably about 10 to 30 cm, and then cut them with a strand cutter. In the production method of this embodiment, the cross section of the elliptical cylindrical pellet has a specific flat cross section. Specifically, the ratio (a / b) of the major axis a to the minor axis b of the cross section of the elliptical cylindrical pellet must be 1.3 to 3.0, preferably 1.35 to 2.95, and more preferably 1.4 to 2.9. When the ratio (a / b) of the major axis a to the minor axis b of the cross section is 1.3 or more, the polymer can be efficiently polymerized. When the ratio (a / b) of the major axis a to the minor axis b of the cross section is 3.0 or less, cracking and chipping of the pellet due to solid-state polymerization can be suppressed. Note that the cross section of the elliptical cylindrical pellet is a cross section perpendicular to the extension direction (length direction) of the elliptical cylinder of the pellet, and the major axis and minor axis of the ellipse correspond to the major axis a and minor axis b of the cross section described above. Specifically, the major and minor axes of the cross section of 100 pellets are measured using an electronic caliper, the number average major axis a and the number average minor axis b are calculated, and the ratio a / b of the major axis a and the minor axis b of the pellet cross section is calculated.

[0111] The length of the elliptical cylindrical pellets is preferably 1.5 to 5.0 mm, more preferably 2.0 to 4.5 mm, and particularly preferably 2.5 to 4.0 mm. By setting the length of the elliptical cylindrical pellets within this range, the pellets become easier to handle.

[0112] The materials used in the melt-kneading step will be described in detail below. ·Thermoplastic resin The thermoplastic resin has a viscosity number RV of 25 to 70, preferably 27 to 65, more preferably 30 to 60, and even more preferably 45 to 60. When the viscosity number RV is within the above range, the degree of polymerization of the thermoplastic resin is within an appropriate range, and the thermoplastic resin is kneaded with the glass fiber in a state where a large amount of polyamide terminals is present, thereby improving the adhesion at the interface between the glass fiber and the thermoplastic resin. The viscosity number RV is expressed as a value measured with 90% formic acid at 25°C as specified in ASTM D789.

[0113] Although various thermoplastic resins can be used as the thermoplastic resin, it is preferable to use polyamide or polyester, and it is more preferable to use polyamide, because the effects of obtaining a higher molecular weight composition in the same solid-state polymerization time and the effects of shortening the time required for solid-state polymerization are more pronounced.

[0114] Examples of the polyamide include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polytetramethylene sebacamide (nylon 410), polypentamethylene adipamide (nylon 56), polypentamethylene sebacamide (nylon 510), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polydecamethylene adipamide (nylon 106), polydecamethylene sebacamide (nylon 1010), polydecamethylene adipamide (nylon 1010), polydecam ... Camethylene dodecamide (Nylon 1012), Polyundecaneamide (Nylon 11), Polydodecanamide (Nylon 12), Polycaproamide / Polyhexamethylene adipamide copolymer (Nylon 6 / 66), Polycaproamide / Polyhexamethylene terephthalamide copolymer (Nylon 6 / 6T), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide copolymer (Nylon 66 / 6T), Polyhexamethylene adipamide / Polyhexamethylene isophthalamide copolymer (Nylon 66 / 6I), Polyhexamethylene terephthalamide Polyhexamethylene terephthalamide / Polyhexamethylene isophthalamide copolymer (Nylon 6T / 6I), Polyhexamethylene terephthalamide / Polyundecaneamide copolymer (Nylon 6T / 11), Polyhexamethylene terephthalamide / Polydodecanamide copolymer (Nylon 6T / 12), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide / Polyhexamethylene isophthalamide copolymer (Nylon 66 / 6T / 6I), Polyxylylene adipamide (Nylon XD6), Polyxylylene sebacamide (Nylon XD10), Poly Examples include polyhexamethylene terephthalamide / polypentamethylene terephthalamide copolymer (nylon 6T / 5T), polyhexamethylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer (nylon 6T / M5T), polypentamethylene terephthalamide / polydecamethylene terephthalamide copolymer (nylon 5T / 10T), polynonamethylene terephthalamide (nylon 9T), polydecamethylene terephthalamide (nylon 10T), and polydodecamethylene terephthalamide (nylon 12T).The " / " used here indicates a copolymer. These polyamides may be used singly or in combination of two or more. Among these, it is preferable to use one selected from the group consisting of polyamide 6, polyamide 66, polyamide 46, polyamide 610, and polyamide 612 as the polyamide, and it is particularly preferable to use polyamide 66. Polyamide 66 itself is a commonly known polyamide resin and is usually produced by polycondensation of hexamethylenediamine and adipic acid. Alternatively, polyamide 66 may be a copolymer containing less than 30% by mass of at least one monomer unit selected from the group consisting of lactam, aminocarboxylic acid, and combinations of other diamines and dicarboxylic acids, based on the total mass of all monomer units.

[0115] These polyamides may be commercially available or may be produced by known methods. Specific methods for producing polyamides are not particularly limited, but examples include the methods described in the first embodiment, such as the ring-opening polymerization method of lactam, the self-condensation method of ω-aminocarboxylic acid, and the condensation method of diamine and dicarboxylic acid.

[0116] Furthermore, the polyamide preferably has a value [NH2] / [COOH] obtained by dividing the amount of amino terminal groups by the amount of carboxy terminal groups of 0.5 or more and 0.9 or less, more preferably 0.5 or more and less than 0.6. When [NH2] / [COOH] is within the above range, the interaction between the surface of the glass fiber and the polyamide terminals becomes sufficiently large during melt kneading, and the physical properties of the resulting composition become sufficiently high. The amount of amino terminal groups and the amount of carboxy terminal groups can be, for example, 1 It can be measured using H-NMR.

[0117] The polyester is a polycondensate of a polycarboxylic acid (dicarboxylic acid) and a polyalcohol (diol). Examples of the polycarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid. Examples of the polyalcohol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. These components may be used alone or in combination of two or more. Specific examples of the polyester include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate.

[0118] Glass fiber It is preferable to use glass fibers that have been bundled with a known binder containing an acrylic resin, an epoxy resin, a urethane resin, or the like as a main component, and it is more preferable to use glass fibers that have been bundled with a binder containing an acrylic resin or an epoxy resin as a main component. Furthermore, since further improvement in the mechanical properties of the resulting molded article is expected, it is preferable to use glass fibers that have been pre-treated with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanate compound, an organic borane compound, or an epoxy compound.

[0119] The average fiber length of the glass fibers in the melt-kneaded product is preferably 100 μm or more and 1000 μm or less. When the average fiber length of the glass fibers is 100 μm or more, the reinforcing effect can be more reliably exhibited, and the impact strength and tensile strength of the resulting thermoplastic resin composition can be further improved. On the other hand, when the average fiber length of the glass fibers is 1000 μm or less, it is possible to more effectively prevent the glass fibers from flying out of the pellets when the resulting melt-kneaded product is pelletized, thereby reducing the bulk density of the pellets. The average fiber length of the glass fibers can be measured, for example, by the following method. First, 100 or more glass fibers are arbitrarily selected, and the total mass of the glass fibers is measured. Next, the glass fibers are observed with an optical microscope, a scanning electron microscope, or the like to measure the fiber length of each glass fiber. The total value is divided by the total mass of the glass fibers to obtain the weight-average fiber length.

[0120] The average fiber diameter of the glass fibers is 3 μm or more and 15 μm or less, preferably 4 μm or more and 13 μm or less, and more preferably 5 μm or more and 10 μm or less. That is, the glass fibers used as raw materials are preferably very thin. When the average fiber diameter of the glass fibers is 3 μm or more, the strength of the glass fibers is sufficiently high, and the reinforcing effect is more sufficiently exhibited. When the average fiber diameter of the glass fibers is 15 μm or less, the surface area of ​​the glass fibers is sufficiently large, and the effect of further strengthening the adhesion at the interface between the glass fibers and the resin is fully exhibited. The average fiber diameter of the glass fibers can be measured, for example, by the following method. First, 100 glass fibers are arbitrarily selected. Next, the glass fibers are observed with an optical microscope, a scanning electron microscope, or the like to measure the fiber diameter of each glass fiber. The total value is divided by 100 to obtain the number average fiber diameter.

[0121] ·Copper compounds In the melt-kneading step, a copper compound may be blended in addition to the thermoplastic resin and glass fiber. Examples of copper compounds include inorganic copper salts such as copper (I) chloride, copper (II) chloride, copper (I) bromide, copper (II) bromide, copper (I) iodide (copper iodide), copper sulfate, copper phosphate, copper borate, and copper nitrate; and organic copper salts such as copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, and copper stearate. Alternatively, copper complex salts coordinated with a chelating agent can be used. Of these, copper (I) iodide is preferred. These copper compounds may be used alone or in combination.

[0122] The amount of the copper compound is not particularly limited, but is preferably 0.0001 parts by mass or more and 1 part by mass or less, more preferably 0.005 parts by mass or more and 0.3 parts by mass or less, and even more preferably 0.02 parts by mass or more and 0.1 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin.

[0123] Metal halides In the melt-kneading step, a metal halide may be blended in addition to the thermoplastic resin and glass fiber described above. As the metal halide, potassium halide is preferred. Examples of potassium halide include potassium iodide, potassium bromide, and potassium chloride. Among them, potassium iodide is preferred. These potassium halides may be used alone or in combination of two or more.

[0124] The amount of metal halide to be added is not particularly limited, but is preferably 0.0001 to 1 part by mass, more preferably 0.005 to 0.8 parts by mass, and even more preferably 0.02 to 0.7 parts by mass, per 100 parts by mass of the thermoplastic resin.

[0125] Other resin components In the manufacturing method of this embodiment, as the raw material resin, in addition to thermoplastic resins having a viscosity number within the above range, other thermoplastic resins having a viscosity number outside the above range can be used, as long as the properties of the resulting thermoplastic resin composition are not impaired. Examples of other thermoplastic resins having a viscosity number outside the above range include general-purpose resins such as polyethylene, polypropylene, ethylene-propylene copolymer, polystyrene, ABS resin, AS resin, and acrylic resin; aliphatic polyamide resins such as polyamide 6 and polyamide 11; polycarbonate, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, and polyphenylene sulfide. These other thermoplastic resins are preferably modified with a modifier such as maleic anhydride or a glycidyl group-containing monomer before use. In particular, resins without functional groups, such as polyethylene, polypropylene, and ethylene-propylene copolymer, are preferably modified before use.

[0126] (Heating process) The heating step in the manufacturing method of this embodiment is a step of heating the molten kneaded product at a temperature T represented by the following general formula (I) to polymerize the thermoplastic resin in the molten kneaded product by solid-state polymerization, thereby obtaining a thermoplastic resin composition. Tm-130℃≦T≦Tm-10℃ (I) (In the formula, Tm is the melting point of the thermoplastic resin.)

[0127] The molten mixture obtained in the melt-kneading step may be directly introduced from the extruder into a solid-state polymerization reactor to carry out solid-state polymerization, or may be temporarily packaged in a paper bag or the like and stored, and then added to the solid-state polymerization reactor to carry out solid-state polymerization.

[0128] By setting the heating temperature T in the heating step to "the melting point of the thermoplastic resin - 130°C" or higher, the reaction can be accelerated, polymerization can be efficiently carried out, and the target degree of polymerization can be achieved. Furthermore, by setting the heating temperature T to "the melting point of the thermoplastic resin - 10°C" or lower, thermal decomposition of the thermoplastic resin can be further suppressed, and color deterioration on the polymer surface can be suppressed, as well as fusion of the composition pellets to each other can be further suppressed. The melting point Tm of the polyamide resin composition can be measured in accordance with JIS-K7121. As a measuring device, for example, Diamond DSC manufactured by PERKIN-ELMER can be used. Specifically, it can be measured using the method shown in the examples described later.

[0129] In the heating step, the heating time of the molten kneaded product is preferably 30 minutes to 15 hours within the above temperature range. By setting the heating time to the above lower limit or more, the thermoplastic resin composition can be made to reach the desired viscosity (degree of polymerization of the thermoplastic resin) more efficiently. By setting the heating time to the above upper limit or less, fusion of the low-order condensate during solid-state polymerization and coloration (yellowing) of the composition can be more effectively suppressed.

[0130] The solid-state polymerization reaction can be carried out either continuously or batchwise. The solid-state polymerization reactor may be either vertical or horizontal. The solid-state polymerization reaction is preferably stirred to improve the uniformity of the reaction. The polymerization reactor may be a rotary type or may be an agitation type using a stirring blade or the like. In particular, the solid-state polymerization reaction in the heating step is preferably carried out continuously.

[0131] The solid-state polymerization reaction in the heating step can be carried out either in vacuum or under an air flow, but is preferably carried out under an inert gas flow such as nitrogen gas.

[0132] When the solid-state polymerization is carried out in an inert gas stream, it is preferably carried out in an inert gas atmosphere with an oxygen concentration of 5 ppm or less. By ensuring an oxygen concentration of 5 ppm or less, oxidative degradation of the resulting thermoplastic resin composition can be more effectively suppressed. This can more effectively suppress the reaction of molecular chain scission and the decrease in the rate of molecular weight increase (polymerization reaction rate), allowing a thermoplastic resin composition of a predetermined molecular weight to be obtained. Furthermore, it can more effectively suppress the decrease in mechanical properties and yellowing of the resulting thermoplastic resin.

[0133] Furthermore, when solid-state polymerization is carried out under an inert gas stream, it is preferably carried out under an inert gas atmosphere with a water concentration of 10 ppm or less. By keeping the water concentration at 10 ppm or less, the progress of the hydrolysis reaction of the thermoplastic resin can be more effectively suppressed. This makes it possible to more effectively suppress a decrease in the rate at which the molecular weight increases (polymerization reaction rate), and a thermoplastic resin composition with a predetermined molecular weight can be obtained.

[0134] Furthermore, when the solid-state polymerization is carried out under an inert gas stream, it is preferable to form a particle layer using molten kneaded pellets, and to carry out the solid-state polymerization reaction while supplying the inert gas to a position at a height of 0 to 0.8 times, preferably 0 to 0.5 times, the height h of the particle layer at a rate of 50 L / hour to 1,000 L / hour, preferably 100 L / hour to 900 L / hour, particularly preferably 200 L / hour to 800 L / hour, per 10 kg of molten kneaded pellets. The height h of the particle layer of the melt-kneaded pellets is defined as follows: A solid-state polymerization reactor is opened, and an amount of melt-kneaded particles or pellets equivalent to that required for operation is charged at room temperature and atmospheric pressure. A predetermined amount of inert gas is passed through the reactor, and the height of the particle layer is measured using the bottom of the reactor where the gas supply port is located as the reference (h=0), and this height is defined as h. If the height of the particle layer fluctuates, the highest and lowest heights can be measured, and the average value of these heights can be defined as h.

[0135] <Thermoplastic resin composition> The thermoplastic resin composition obtained by the production method of this embodiment is excellent in mechanical properties, long-term properties, and productivity. Furthermore, the thermoplastic resin composition of the present embodiment preferably has a viscosity number RV of 70 or more and 400 or less, more preferably 80 or more and 380 or less, even more preferably 90 or more and 350 or less, and even more preferably 150 or more and 200 or less. When the RV is at least the above lower limit, the mechanical properties are better, while when the RV is at most the above upper limit, the molding processability is better when molded for each application.

[0136] Furthermore, the content of the glass fiber in the thermoplastic resin composition of this embodiment is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 10 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin. When the content of the glass fiber is 5 parts by mass or more relative to 100 parts by mass of the thermoplastic resin, the rigidity and strength of the thermoplastic resin composition can be further increased, while when the content of the glass fiber is 100 parts by mass or less relative to 100 parts by mass of the thermoplastic resin, the moldability of the thermoplastic resin composition when molded for each application is improved.

[0137] Furthermore, the weight-average fiber length of the glass fibers contained in the thermoplastic resin composition of this embodiment is preferably 100 μm or more and 1000 μm or less. When the average fiber length of the glass fibers is 100 μm or more, the reinforcing effect can be more fully exhibited, and the impact strength and tensile strength can be further improved. On the other hand, when the thermoplastic resin composition is pelletized, when the average fiber length of the glass fibers is 1000 μm or less, it is possible to more effectively prevent the glass fibers from flying out of the pellets, which would result in a decrease in the bulk density of the pellets.

[0138] The average fiber length of the glass fibers contained in the thermoplastic resin composition can be measured, for example, by the following method. First, the thermoplastic resin composition is dissolved in a solvent in which the thermoplastic resin is soluble, such as formic acid. Next, from the resulting insoluble components, for example, 100 or more glass fibers are arbitrarily selected, and the total mass of the glass fibers is measured. Next, the glass fibers are observed using an optical microscope, a scanning electron microscope, or the like to measure the fiber length of each glass fiber, and the total value is divided by the total mass of the glass fibers to obtain the weight-average fiber length.

[0139] By using the method for producing a thermoplastic resin composition according to the present embodiment, it is possible to promote the production of a high molecular weight resin, thereby improving productivity. In addition, the obtained thermoplastic resin composition has excellent mechanical properties and long-term properties, and is therefore suitable for use in, for example, automobile parts, electronic and electrical parts, industrial machine parts, various gears, and the like.

[0140] <Method of producing thermoplastic resin composition> A method for producing a thermoplastic resin composition according to a fourth embodiment of the present invention includes a melt-kneading step and a heating step. The production method according to this embodiment may consist of only the melt-kneading step and the heating step, or may further include other steps. Descriptions of the same components as those in the first, second, and third embodiments may be omitted. In the melt-kneading step, 5 to 100 parts by mass of glass fibers having an average fiber diameter of 3 μm to 9 μm are added to 100 parts by mass of a thermoplastic resin having a viscosity number VN of 80 to 200, and the mixture is melt-kneaded to obtain a molten kneaded product. The molten kneaded product may be a kneaded product consisting only of the thermoplastic resin and the glass fibers, or may further contain other components. In the heating step, the melt-kneaded product obtained in the melt-kneading step is heated at a temperature T represented by the following mathematical formula (I) to obtain a thermoplastic resin composition. In this specification, the unit of the temperature T and the melting point Tm is ° C. Tm-130℃≦T≦Tm-10℃ (I) (wherein Tm is the melting point of the thermoplastic resin.) In the heating step, the melt-kneaded product obtained in the melt-kneading step contains 0.05 to 1.0% by mass of water relative to 100% by mass.

[0141] In a typical method for producing a thermoplastic resin composition, a thermoplastic resin is polymerized to a high molecular weight, and then a filler such as glass fiber is added, followed by melt-kneading to obtain a thermoplastic resin composition.

[0142] In contrast, in the manufacturing method of this embodiment, a molten kneaded product is obtained by melt-kneading a low- to medium-molecular-weight thermoplastic resin with glass fibers. This improves the degree of adhesion at the interface between the glass fibers and the thermoplastic resin. The molten kneaded product is then solid-phase polymerized to increase its molecular weight in a heating step, thereby maintaining the improved degree of adhesion at the interface between the glass fibers and the thermoplastic resin, and a thermoplastic resin composition with excellent vibration fatigue resistance can be obtained. Furthermore, by performing the melt-kneading step and the heating step in this order, the improved degree of adhesion at the interface between the glass fibers and the thermoplastic resin is maintained, making it less likely for the filler to fall off during manufacturing.

[0143] Each step of the manufacturing method of this embodiment will be described in detail below.

[0144] [Melting and kneading process] In the melt-kneading step, glass fibers having an average fiber diameter of 3 μm or more and 9 μm or less are added to a thermoplastic resin having a viscosity number VN of 80 or more and 200 or less at a specific blending ratio, and the mixture is melt-kneaded to obtain a melt-kneaded product. Specifically, the glass fibers can be added in an amount of 5 parts by mass to 100 parts by mass, preferably 10 parts by mass to 100 parts by mass, more preferably 15 parts by mass to 100 parts by mass, and even more preferably 20 parts by mass to 90 parts by mass, per 100 parts by mass of the thermoplastic resin. When the blending amount of glass fiber is equal to or more than the above lower limit, a thermoplastic resin composition having increased rigidity and strength can be obtained, while when the blending amount is equal to or less than the above upper limit, the resulting thermoplastic resin composition has better moldability when molded for each application.

[0145] Known melt-kneading devices can be used. For example, melt-kneading devices such as single-screw or twin-screw extruders, Banbury mixers, and mixing rolls can be used. Among these, multi-screw extruders equipped with a devolatilizing mechanism (vent) and a side feeder are preferred, and twin-screw extruders are more preferred.

[0146] When melt-kneading is performed using an extruder, the molecular weight of the thermoplastic resin after melt-kneading can be adjusted by appropriately setting the kneading conditions such as the resin temperature, degree of vacuum, and average residence time during extrusion.

[0147] The resin temperature during melt-kneading is preferably from the melting point of the raw thermoplastic resin to 370°C, more preferably from the melting point of the raw thermoplastic resin + 5°C to 350°C, even more preferably from the melting point of the raw thermoplastic resin + 10°C to 340°C, particularly preferably from the melting point of the raw thermoplastic resin + 15°C to 335°C, and most preferably from the melting point of the raw thermoplastic resin + 20°C to 330°C. By setting the resin temperature during melt-kneading to the above lower limit or higher, the raw thermoplastic resin melts sufficiently, which tends to further reduce the load on the melt-kneader, such as the extruder motor, etc. Furthermore, by setting the resin temperature during melt-kneading to the above upper limit or lower, decomposition of the raw thermoplastic resin itself tends to be further suppressed.

[0148] By appropriately setting the melt-kneading (e.g., extrusion) conditions such as resin temperature, degree of vacuum, and average residence time, the weight-average molecular weight of the thermoplastic resin after melt-kneading is controlled to be in the low to medium molecular weight range. Here, the low to medium molecular weight range means a weight-average molecular weight range of 10,000 to 70,000, 15,000 to 65,000, or 20,000 to 60,000.

[0149] For example, when polyamide 66 having a melting point of 264°C is used as the raw thermoplastic resin, the resin temperature during melt-kneading is preferably 264°C or higher and 360°C or lower, more preferably 270°C or higher and 350°C or lower, even more preferably 275°C or higher and 340°C or lower, particularly preferably 280°C or higher and 335°C or lower, and most preferably 285°C or higher and 330°C or lower. By setting the resin temperature during melt-kneading to be equal to or higher than the above lower limit, polyamide 66 is more thoroughly melted, and the load on the melt-kneader, such as the extruder motor, tends to be further reduced. Furthermore, by setting the resin temperature during melt-kneading to be equal to or lower than the above upper limit, decomposition of polyamide 66 itself tends to be further suppressed.

[0150] Even when a polyamide resin other than polyamide 66 is used as the raw material polyamide resin, the temperature can be appropriately adjusted depending on its melting point. The resin temperature can be measured, for example, by directly contacting a thermometer such as a thermocouple with the molten mixture discharged from the extruder outlet (spinning nozzle). The resin temperature can be adjusted by adjusting the heater temperature of the extruder cylinder or by appropriately adjusting the shear heat generation of the resin by changing the extruder rotation speed and discharge rate.

[0151] The average residence time during melt-kneading is preferably from 10 seconds to 120 seconds, more preferably from 20 seconds to 100 seconds, even more preferably from 25 seconds to 90 seconds, particularly preferably from 30 seconds to 80 seconds, and most preferably from 35 seconds to 70 seconds. By setting the average residence time during melt-kneading to be equal to or greater than the lower limit, the melt-kneaded product tends to be obtained more efficiently. Furthermore, by setting the average residence time during melt-kneading to be equal to or less than the upper limit, the extrusion discharge rate (production rate) tends to increase to some extent. As a result, the productivity of thermoplastic resin compositions such as polyamide resin compositions also tends to be improved. The average residence time means the residence time in the melt-kneading device when the residence time is constant. When the residence time is not uniform, it means the average value between the shortest residence time and the longest residence time.

[0152] The average residence time is measured by the following method. Component X is added to a melt-kneading device, and the discharge start time and discharge end time are measured when component X is at its most concentrated. The average residence time can be measured by averaging the measured discharge start time and discharge end time. Component X is a component that can be distinguished from the raw material polyamide resin used in the melt-kneading process, such as a colorant masterbatch during melt-kneading, or a resin used in the melt-kneading process that has a different color from the raw material polyamide resin. The average residence time can be adjusted appropriately by adjusting the discharge amount (discharge speed) and rotation speed of the extruder.

[0153] The melt-kneaded product obtained by melt-kneading may be resin pellets, which can be provided in various shapes. Preferred pellet shapes include round, elliptical, and cylindrical shapes, which vary depending on the cutting method used during extrusion processing. Pellets cut by a cutting method called underwater cutting are often round, pellets cut by a cutting method called hot cutting are often round or elliptical, and pellets cut by a cutting method called strand cutting are often cylindrical.

[0154] The round pellets may not be perfect spheres or perfect spheres, but may have a shape that approximates a sphere. The preferred size of the round pellets is a pellet diameter (maximum diameter in the case of approximations to a sphere) of 8 mm or less, more preferably 0.5 mm to 6 mm, and even more preferably 1 mm to 5 mm.

[0155] The oval pellets may not be ellipsoids or perfect ellipsoids, but may have a shape that approximates an ellipsoid. In the case of oval pellets, the preferred size is a pellet major axis (maximum major axis in the case of an ellipsoid approximation) of 8 mm or less, more preferably 0.5 mm to 6 mm, and even more preferably 1 mm to 5 mm.

[0156] The cylindrical pellets may not be cylindrical or may have a shape that approximates a cylindrical shape. The preferred size of the cylindrical pellets is a pellet diameter (maximum diameter in the case of a cylindrical approximation) of 1 mm to 3 mm, and a preferred length of 2 mm to 10 mm.

[0157] The raw materials used in the melt-kneading step will be described in detail below.

[0158] (thermoplastic resin) The thermoplastic resin may have a viscosity number VN of 80 or more and 200 or less, preferably 100 or more and 200 or less, and more preferably 130 or more and 190 or less. When the viscosity number VN is within the above range, the degree of polymerization of the thermoplastic resin is within an appropriate range, and the adhesion at the interface between the glass fiber and the thermoplastic resin can be improved. The viscosity number VN is a value measured in accordance with ISO307 (JIS-K6933). For example, it can be measured using the method shown in the examples below. The resin component in the thermoplastic resin composition may consist solely of the above-mentioned thermoplastic resin having a viscosity number VN within the above-mentioned range.

[0159] Specifically, the thermoplastic resin is preferably polyamide or polyester, and more preferably polyamide.

[0160] Examples of polyamides include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polytetramethylene sebacamide (nylon 410), polypentamethylene adipamide (nylon 56), polypentamethylene sebacamide (nylon 510), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polydecamethylene adipamide (nylon 106), polydecamethylene sebacamide (nylon 1010), and polydeca Methylene dodecamide (Nylon 1012), Polyundecaneamide (Nylon 11), Polydodecanamide (Nylon 12), Polycaproamide / Polyhexamethylene adipamide copolymer (Nylon 6 / 66), Polycaproamide / Polyhexamethylene terephthalamide copolymer (Nylon 6 / 6T), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide copolymer (Nylon 66 / 6T), Polyhexamethylene adipamide / Polyhexamethylene isophthalamide copolymer (Nylon 66 / 6I), Polyhexamethylene terephthalamide Phthalamide / Polyhexamethylene isophthalamide copolymer (Nylon 6T / 6I), Polyhexamethylene terephthalamide / Polyundecaneamide copolymer (Nylon 6T / 11), Polyhexamethylene terephthalamide / Polydodecanamide copolymer (Nylon 6T / 12), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide / Polyhexamethylene isophthalamide copolymer (Nylon 66 / 6T / 6I), Polyxylylene adipamide (Nylon XD6), Polyxylylene sebacamide (Nylon XD10), Poly Examples include polyhexamethylene terephthalamide / polypentamethylene terephthalamide copolymer (nylon 6T / 5T), polyhexamethylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer (nylon 6T / M5T), polypentamethylene terephthalamide / polydecamethylene terephthalamide copolymer (nylon 5T / 10T), polynonamethylene terephthalamide (nylon 9T), polydecamethylene terephthalamide (nylon 10T), and polydodecamethylene terephthalamide (nylon 12T).The " / " used here indicates a copolymer. These polyamides may be used singly or in combination of two or more.

[0161] Among these, polyamides, polyamide 6, polyamide 66, and polyamide 610 are preferred, with polyamide 66 being particularly preferred. Polyamide 66 itself is a commonly known polyamide resin, and is typically produced by polycondensation of hexamethylenediamine and adipic acid. Alternatively, polyamide 66 may be a copolymer containing less than 30% by mass of at least one monomer unit selected from the group consisting of lactams, aminocarboxylic acids, and combinations of other diamines and dicarboxylic acids, based on the total mass of all monomer units.

[0162] These polyamides may be commercially available or may be produced by known methods. Specific methods for producing polyamides are not particularly limited, but examples include the methods described in the first embodiment, such as the ring-opening polymerization method of lactam, the self-condensation method of ω-aminocarboxylic acid, and the condensation method of diamine and dicarboxylic acid.

[0163] The value [COOH] / [NH2] obtained by dividing the amount of amino terminal groups in the polyamide by the amount of carboxy terminal groups is preferably 0.5 or more and 0.9 or less. When [COOH] / [NH2] is equal to or more than the lower limit, solid-state polymerization can be carried out more efficiently in the heating step described below. When [COOH] / [NH2] is equal to or less than the upper limit, the interaction between the surface of the glass fiber and the polyamide terminal becomes sufficiently large, and the physical properties of the obtained composition, particularly the vibration fatigue resistance, are sufficiently high. The amount of amino terminal groups and the amount of carboxy terminal groups can be, for example, 1 It can be measured using H-NMR.

[0164] Polyester is a polycondensate of a polycarboxylic acid (dicarboxylic acid) and a polyalcohol (diol). Examples of polycarboxylic acids include terephthalic acid and 2,6-naphthalenedicarboxylic acid. Examples of polyalcohols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. These components may be used alone or in combination of two or more. Specific examples of polyesters include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate.

[0165] (glass fiber) The glass fibers to be used are preferably those bound with a known binder containing an acrylic resin, an epoxy resin, a urethane resin, or the like as a main component, and more preferably those bound with a binder containing an acrylic resin or an epoxy resin as a main component. Furthermore, since further improvement in the mechanical properties of the resulting molded product is expected, it is preferable to use glass fibers that have been pre-treated with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanate compound, an organic borane compound, or an epoxy compound.

[0166] The average fiber length of the glass fibers is preferably 100 μm or more and 1000 μm or less. When the average fiber length is equal to or greater than the lower limit, the reinforcing effect is more fully exerted, and the impact strength and tensile strength of the resulting thermoplastic resin composition can be further improved. On the other hand, when the average fiber length is equal to or less than the upper limit, when the resulting thermoplastic resin composition is pelletized, the glass fibers are less likely to come off the pellets. This makes it more difficult for the bulk density of the pellets to decrease.

[0167] The average fiber length of the glass fibers can be measured, for example, by the following method. First, for example, 100 or more glass fibers are arbitrarily selected and the total mass of the glass fibers is measured. Next, the glass fibers are observed with an optical microscope, a scanning electron microscope, or the like to measure the fiber length of each glass fiber, and the total value is divided by the total mass of the glass fibers to obtain the weight-average fiber length.

[0168] The average fiber diameter of the glass fibers is 3 μm or more and 9 μm or less, preferably 4 μm or more and 8 μm or less, and more preferably 5 μm or more and 7 μm or less. When the average fiber diameter is equal to or greater than the lower limit, the strength of the glass fibers is sufficiently high, and the reinforcing effect is more sufficiently exhibited. When the average fiber diameter is equal to or less than the upper limit, the surface area of ​​the glass fibers is sufficiently large, and the effect of further strengthening the adhesion at the interface between the glass fibers and the resin is fully exhibited.

[0169] The average fiber diameter of the glass fibers can be measured, for example, by the following method. First, for example, 100 glass fibers are arbitrarily selected. Then, the glass fibers are observed using an optical microscope, a scanning electron microscope, or the like to measure the fiber diameter of each glass fiber. The total value is divided by 100 to obtain the number average fiber diameter.

[0170] Commonly used glass fibers are called "E-glass" and contain approximately 7 mass % of boron oxide relative to the total mass of the glass fibers. The glass fibers contained in the thermoplastic resin composition of this embodiment preferably contain substantially no boron oxide in their composition. In other words, the resulting thermoplastic resin composition preferably contains substantially no boron oxide. By being substantially free of boron oxide, the physical properties of the composition, particularly vibration fatigue resistance, become better. Here, "substantially free of boron oxide" means that boron oxide is not contained at all, or that only a trace amount of boron oxide is contained so as not to impair the properties (particularly vibration fatigue resistance) of the obtained thermoplastic resin composition. Specifically, the content of boron oxide is preferably less than 5% by mass, more preferably less than 1% by mass, even more preferably less than 0.1% by mass, and particularly preferably 0% by mass, relative to the total mass of the thermoplastic resin composition.

[0171] (copper compound) In the melt-kneading step, a copper compound may be blended in addition to the thermoplastic resin and the glass fiber. Examples of copper compounds include inorganic copper salts such as copper (I) chloride, copper (II) chloride, copper (I) bromide, copper (II) bromide, copper (I) iodide (copper iodide), copper sulfate, copper phosphate, copper borate, and copper nitrate; and organic copper salts such as copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, copper isophthalate, and copper stearate. Alternatively, copper complex salts coordinated with a chelating agent can be used. Of these, copper (I) iodide is preferred. These copper compounds may be used alone or in combination.

[0172] The amount of the copper compound is preferably 0.0001 to 1 part by mass, more preferably 0.005 to 0.2 parts by mass, and even more preferably 0.02 to 0.1 parts by mass, per 100 parts by mass of the thermoplastic resin.

[0173] (metal halide) In the melt-kneading step, a metal halide may be blended in addition to the thermoplastic resin and the glass fiber. As the metal halide, potassium halide is preferred. Examples of potassium halide include potassium iodide, potassium bromide, and potassium chloride. Among them, potassium iodide is preferred. These potassium halides may be used alone or in combination of two or more.

[0174] The amount of the metal halide to be added is preferably 0.0001 to 1 part by mass, more preferably 0.005 to 0.2 parts by mass, and even more preferably 0.02 to 0.15 parts by mass, per 100 parts by mass of the thermoplastic resin.

[0175] (Other resin components) In the manufacturing method of this embodiment, as the raw material resin, in addition to thermoplastic resins having a viscosity number within the above range, other thermoplastic resins having a viscosity number outside the above range can be used, as long as the properties of the resulting thermoplastic resin composition are not impaired.

[0176] Examples of other thermoplastic resins having a viscosity number outside the above range include general-purpose resins such as polyethylene, polypropylene, ethylene-propylene copolymer, polystyrene, ABS resin, AS resin, and acrylic resin; aliphatic polyamide resins such as polyamide 6 and polyamide 11; polycarbonate, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, and polyphenylene sulfide. These other thermoplastic resins are preferably modified with a modifier such as maleic anhydride or a glycidyl group-containing monomer before use. In particular, resins without functional groups, such as polyethylene, polypropylene, and ethylene-propylene copolymer, are preferably modified before use.

[0177] [Heating process] In the heating step, the melt-kneaded product is heated at a temperature T represented by the following general formula (I), and the thermoplastic resin in the melt-kneaded product is polymerized by solid-phase polymerization to obtain a thermoplastic resin composition. Tm-130℃≦T≦Tm-10℃ (I) (wherein Tm is the melting point of the thermoplastic resin.)

[0178] The molten mixture obtained in the melt-kneading step may be introduced directly from the extruder into a solid-state polymerization reactor to carry out solid-state polymerization, or may be temporarily packaged in a paper bag or the like and stored, and then added to a solid-state polymerization reactor to carry out solid-state polymerization.

[0179] By setting the temperature T to "the melting point of the thermoplastic resin - 130°C" or higher, the polymerization reaction can be accelerated, polymerization can be carried out efficiently, and the desired degree of polymerization can be achieved. By keeping the temperature T at or below the melting point of the thermoplastic resin minus 10°C, the thermoplastic resin is less susceptible to thermal decomposition, which can prevent discoloration and deterioration on the polymer surface. In addition, fusion of solid prepolymers to each other can be further prevented. The temperature T is preferably Tm-110°C or higher and Tm-30°C or lower.

[0180] The melting point Tm of the thermoplastic resin can be measured in accordance with JIS-K7121. As a measuring device, for example, Diamond DSC manufactured by PERKIN-ELMER can be used. Specifically, it can be measured using the method shown in the examples described later.

[0181] In the heating step, the heating time of the molten kneaded product is preferably 30 minutes to 15 hours within the above temperature range. By setting the heating time to the above lower limit or more, the thermoplastic resin composition can be made to reach the desired viscosity (degree of polymerization of the thermoplastic resin) more efficiently. By setting the heating time to the above upper limit or less, fusion of the low-order condensate during solid-state polymerization and coloration (yellowing) of the composition can be more effectively suppressed.

[0182] The solid-state polymerization reaction can be carried out either continuously or batchwise. The solid-state polymerization reactor may be either vertical or horizontal. The solid-state polymerization reaction is preferably stirred to improve the uniformity of the reaction. The polymerization reactor may be a rotary type or may be an agitation type using a stirring blade or the like. In particular, the solid-state polymerization reaction in the heating step is preferably carried out continuously.

[0183] Furthermore, water is added during the solid-state polymerization reaction in the heating step. The amount of water is 0.05 to 1.0 mass% relative to 100 mass% of the melt-kneaded pellets obtained by the melt-kneading, preferably 0.06 to 0.9 mass%, more preferably 0.07 to 0.8 mass%, and particularly preferably 0.11 to 0.8 mass%. By adding water in the above amount during the solid-state polymerization reaction, coloration (yellowing) of the composition can be suppressed and vibration fatigue resistance can be improved. The amount of water may be the proportion of water in the heating step before the start of heating.

[0184] Water can be added to the solid-state polymerization reaction, for example, after the molten kneaded material is filled into a solid-state polymerization apparatus. In order to uniformly attach water to the molten kneaded material, it is preferable to add water while stirring the molten kneaded material. Alternatively, water can be added by subjecting the molten kneaded material to a water absorption treatment in advance before carrying out the solid-state polymerization reaction.

[0185] The solid-state polymerization reaction in the heating step can be carried out either in vacuum or under an air flow, but is preferably carried out under an inert gas flow such as nitrogen gas.

[0186] When solid-state polymerization is carried out under an inert gas stream, it is preferably carried out under an inert gas atmosphere with an oxygen concentration of 5 ppm or less. By keeping the oxygen concentration below the upper limit, the resulting thermoplastic resin composition is less susceptible to oxidative degradation. This makes it less likely that a reaction that breaks molecular chains will occur, and the rate at which molecular weight increases (polymerization reaction rate) will not decrease, making it easier to obtain a thermoplastic resin composition with a predetermined molecular weight. In addition, it is possible to more effectively prevent the resulting thermoplastic resin composition from deteriorating in mechanical properties or yellowing.

[0187] When the solid-state polymerization is carried out under an inert gas stream, it is preferable to form a particle layer from the molten mixture and carry out the solid-state reaction while supplying a predetermined amount of inert gas to a predetermined position at a predetermined height of the particle layer. Specifically, an inert gas is introduced at a height of 0 to 0.8 times, preferably 0 to 0.5 times the height h of the particle layer at a rate of 0.1 Nm per 1 kg of the molten mixture. 3 / hour over 10Nm 3 / hour or less, preferably 0.14 Nm 3 / hour over 10Nm 3 It is preferable to carry out the solid-state polymerization reaction while supplying the catalyst in an amount of 1 / hour or less.

[0188] The height h of the particle layer is defined as follows: The solid-state polymerization reactor is opened, and particles or pellets of the melt-kneaded product in an amount equivalent to that of operation are charged at room temperature and atmospheric pressure. A predetermined amount of inert gas is passed through the reactor, and the height of the particle layer is measured and defined as h, with the bottom of the reactor where the gas supply port is located as the reference (h=0). If the height of the particle layer is not constant, the average value of the maximum height and the minimum height is taken as h.

[0189] The ratio of the viscosity number VN of the thermoplastic resin composition after the heating step to the viscosity number VN of the thermoplastic resin added in the melt-kneading step (viscosity number VN of the thermoplastic resin composition after the heating step / viscosity number VN of the thermoplastic resin added in the melt-kneading step) is preferably 1.0 to 5.0, more preferably 1.1 to 4.0, and even more preferably 1.2 to 3.0, from the viewpoint of further improving vibration fatigue resistance and further suppressing discoloration.

[0190] <Thermoplastic resin composition> The thermoplastic resin composition obtained by the production method of this embodiment preferably has a viscosity number VN of 200 or more and 350 or less, more preferably 210 or more and 330 or less, and even more preferably 220 or more and 300 or less. When VN is equal to or more than the above lower limit, the abrasion resistance is better, while when VN is equal to or less than the above upper limit, the molding processability is better when molded for each application.

[0191] The content of glass fibers in the thermoplastic resin composition is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 15 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin. When the content of glass fibers is equal to or more than the above lower limit, the rigidity and strength of the thermoplastic resin composition can be further increased, while when the content is equal to or less than the above upper limit, the thermoplastic resin composition has better moldability when molded for various applications.

[0192] The average fiber length of the glass fibers contained in the thermoplastic resin composition is preferably 100 μm or more and 1000 μm or less, more preferably 200 μm or more and 600 μm or less, and even more preferably 300 μm or more and 500 μm or less. When the average fiber length is equal to or greater than the above lower limit, the reinforcing effect is more fully exerted, and impact strength and tensile strength can be further improved. On the other hand, when the thermoplastic resin composition is pelletized, when the average fiber length is equal to or greater than the above lower limit, the glass fibers are less likely to come off the pellets. This makes it less likely that the bulk density of the pellets will decrease.

[0193] The average fiber length of the glass fibers contained in the thermoplastic resin composition can be measured, for example, by the following method. First, the thermoplastic resin composition is dissolved in a solvent in which the thermoplastic resin is soluble, such as formic acid. Next, for example, 100 or more glass fibers are arbitrarily selected from the insoluble components obtained, and the total mass of the glass fibers is measured. The glass fibers are then observed with an optical microscope, a scanning electron microscope, or the like to measure the fiber length of each glass fiber, and the total value is divided by the total mass of the glass fibers to obtain the weight-average fiber length.

[0194] The thermoplastic resin composition obtained by the production method of this embodiment has excellent vibration fatigue resistance and is therefore suitable for use in, for example, automobile parts, electronic and electrical parts, industrial machine parts, various gears, and the like. [Example]

[0195] The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples. The raw materials and measurement methods for physical property tests used in the examples and comparative examples are as follows.

[0196] [Raw materials] (A1) Crystalline polyamide Production Example 1-1: Polyamide 66-1 (A1-1) 15,000 g of an equimolar salt of adipic acid and hexamethylenediamine, along with 0.5 mol% excess adipic acid relative to the total equimolar salt components, were dissolved in 15,000 g of distilled water to obtain a 50% by mass aqueous solution of the raw material monomer. The resulting aqueous solution was placed in a 40 L autoclave, and the autoclave was purged with nitrogen. The aqueous solution was concentrated to a solution concentration of 70% by mass by gradually removing steam while stirring at a temperature of 110 to 150°C. The internal temperature was then raised to 220°C. At this time, the autoclave was pressurized to 1.8 MPa. The reaction was continued for 1 hour while gradually removing steam to maintain the pressure at 1.8 MPa until the internal temperature reached 270°C. The pressure was then reduced to atmospheric pressure over approximately one hour. After atmospheric pressure was reached, the mixture was discharged in the form of strands from the lower nozzle, water-cooled, and cut to obtain crystalline polyamide pellets. The resulting pellets were dried in a nitrogen stream at 90°C for four hours. The crystalline polyamide pellets had a relative viscosity in formic acid of 45, a melting point of 265°C, and a crystallization temperature of 220°C.

[0197] Production Example 1-2: Polyamide 66-2 (A1-2) 10 kg of the polyamide 66-1 pellets were placed in a conical ribbon vacuum dryer (Okawahara Manufacturing Co., Ltd., product name: Ribocone RM-10V) and thoroughly purged with nitrogen. With nitrogen flowing at 1 L / min, the pellets were heated at 190°C for 6 hours while stirring. The temperature was then lowered while still flowing nitrogen, and when it reached approximately 50°C, the pellets were removed from the dryer. The relative formic acid viscosity of the crystalline polyamide pellets was 130.

[0198] Production Example 1-3: Polyamide 66-3 (A1-3) Pellets were obtained in the same manner as in Production Example 1-2, except that heating was carried out for 8 hours at a pellet temperature of 205° C. The relative viscosity of the crystalline polyamide pellets in formic acid was 250.

[0199] (B1) Glass fiber B1-1: Glass Chopped Strand-1 Nittobo, product name "CS-3DE-456S" (number average diameter of glass fibers 7 μm, weight average length of glass fibers 3 mm, ignition loss 36.5, boron content 13,000 mass ppm) B1-2: Glass Chopped Strand-2 Nippon Electric Glass Co., Ltd., product name "ECS03T-289DE" (number average diameter of glass fibers 7 μm, weight average length of glass fibers 3 mm, ignition loss 13.9, boron content 14,000 mass ppm) B1-3: Glass Chopped Strand-3 Nittobo, product name "CS-3PE-454" (number average diameter of glass fibers: 13 μm, weight average length of glass fibers: 3 mm, ignition loss: 29.2, boron content: 13,000 ppm by mass) B1-4: Glass Chopped Strand-4 Glass fibers prepared in Production Example 1-4 described below (number average diameter of glass fibers: 7 μm, weight average length of glass fibers: 3 mm, loss on ignition: 32.7, boron content: 0 ppm by mass)

[0200] Manufacturing Example 1-4: Glass Chopped Strand-4 The mixture was diluted with water in proportions equivalent to 2% by mass of polyurethane resin (trade name: Bondic (registered trademark) 1050, an aqueous solution with a solids content of 50% by mass (manufactured by Dainippon Ink Co., Ltd.)), 0.6% by mass of γ-aminopropyltriethoxysilane (trade name: KBE-903 (manufactured by Shin-Etsu Chemical Co., Ltd.)), and 0.1% by mass of lubricant [trade name: Carnauba wax (manufactured by Kato Yoko Co., Ltd.)], and the total mass was adjusted to 100% by mass to obtain a glass fiber sizing agent.

[0201] Glass raw materials were mixed in proportions of SiO2: 58 mass%, Al2O3: 14 mass%, CaO: 21 mass%, MgO: 2 mass%, and Na2O + KO: 5 mass%, and these were melt-spun to obtain long glass fibers having a number average fiber diameter of 7 μm, after which the above-mentioned glass fiber sizing agent was attached to the glass fibers. That is, the above-mentioned glass fiber sizing agent was applied to the glass fibers while they were being wound around a rotating drum using an applicator installed at a predetermined position.

[0202] Next, this was dried to obtain a roving (glass roving) of glass fiber bundles surface-treated with the glass fiber sizing agent. At this time, the glass fibers were shaped into a bundle of 1000 fibers. This was cut into a length of 3 mm to obtain glass chopped strand-4. This chopped strand was used as the glass fiber.

[0203] (C1) Component Copper(I) iodide (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0204] Component (D1) Potassium iodide (Fujifilm Wako Pure Chemical Industries, Ltd.)

[0205] Other ingredients Antioxidant: Irganox (registered trademark) 1098 (manufactured by BASF) Colorant: Mitsubishi (registered trademark) Carbon Black #2600 (manufactured by Mitsubishi Chemical Corporation)

[0206] [Example 1-1] A twin-screw extruder (ZSK-40MC, manufactured by Coperion GmbH, Germany) was used as the extruder. This twin-screw extruder had an upstream feed port provided on the first barrel from the upstream side and a downstream feed port provided on the eighth barrel from the upstream side. The L / D (length of the extruder cylinder / diameter of the extruder cylinder) was 48 (number of barrels: 12). In this twin-screw extruder, the temperature from the upstream feed port to the barrel just before the barrel with the downstream feed port was set to 310 to 320°C, the temperature from the barrel with the downstream feed port to the final barrel was set to 290°C, the screw rotation speed was 200 rpm, the discharge rate was 80 kg / h, and the vacuum level was -0.08 MPa.

[0207] Under these conditions, (A1) crystalline polyamide, (C1) component, (D1) component, and other components were supplied from the upstream supply port in proportions that would result in the composition shown in Table 1, and (B1) glass fiber was supplied from the downstream supply port in proportions that would result in the composition shown in Table 1, and the mixture was melt-kneaded to produce pellets of the resin composition.

[0208] 11 kg of the obtained pellets were placed in an incubator (manufactured by Espec Corporation, product name Perfect Oven PHH-202M) and thoroughly purged with nitrogen. With nitrogen flowing at 1 L / min, solid-state polymerization was carried out by heating the pellets at a temperature of 210°C for 2 hours. The temperature was then lowered while still flowing nitrogen, and when it reached approximately 50°C, the pellets were removed from the device as they were.

[0209] The pellets were then molded into ISO 3167, multipurpose test specimens (Type A) using an injection molding machine PS-40E (manufactured by Nissei Plastics Co., Ltd.) at a mold temperature of 80°C and a cylinder temperature of 290°C. These molded specimens were used to evaluate various mechanical properties, vibration fatigue properties, wear properties, etc. The molar ratio of copper content to halogen content was calculated as I / Cu from the proportions of copper (I) iodide and potassium iodide used.

[0210] [Examples 1-2 to 1-18] Pellets and test pieces of the resin compositions of Examples 1-2 to 1-18 were prepared in the same manner as in Example 1-1, except that the types, contents, or solid-state polymerization times of the (A1) crystalline polyamide, (B1) glass fiber, (C1) component, (D1) component, and other components were changed as shown in Tables 1 to 4, and then subjected to the respective tests. In Tables 1-4, the masterbatch containing components (C1) and (D1) is abbreviated as "C1·D1 masterbatch." The C1·D1 masterbatch was prepared by blending 90 parts by mass of polyamide 6 (SF1013A, manufactured by Ube Industries, Ltd.), 1.8 parts by mass of component (C1), and 18 parts by mass of component (D1). The blend was melt-mixed in a twin-screw extruder (TEM35φ twin-screw extruder, manufactured by Toshiba Machine Co., Ltd.) at a screw rotation speed of 200 rpm and a throughput of 90 kg / h. Melt-mixing using the twin-screw extruder was stable. The molar ratio of the halogen content to the copper content (halogen / copper) in the C1·D1 masterbatch was 12 / 1.

[0211] [Comparative Examples 1-1 to 1-5] Using the same twin-screw extruder as in Example 1-1, the temperature from the upstream feed port to the die was set to 300°C, the screw rotation speed to 200 rpm, and the output rate to 15 kg / h. Under these conditions, (A1) crystalline polyamide, (C1) component, (D1) component, and other components were fed through the upstream feed port to the compositions shown in Tables 5-6, and (B1) glass fiber was fed through the downstream feed port to the compositions shown in Tables 5-6. The resin composition pellets were melt-kneaded to produce pellets. The resulting resin composition pellets were molded into ISO 3167 multipurpose test specimen type A using the same injection molding machine as in Example 1-1, with the mold temperature set to 80°C and the cylinder temperature set to 290°C. The molded specimens were used to evaluate various mechanical properties, vibration fatigue properties, wear properties, etc.

[0212] [Comparative Examples 1-6] A twin-screw extruder similar to that used in Example 1-1 was used. The temperature from the upstream feed port to the die was set to 300°C, the screw rotation speed to 200 rpm, and the output rate to 15 kg / h. Under these conditions, (A1) crystalline polyamide, (C1) component, (D1) component, and other components were fed through the upstream feed port to the composition shown in Table 6, and (B1) glass fiber was fed through the downstream feed port to the composition shown in Table 6. The resin composition pellets were produced by melt-kneading. 11 kg of the resulting pellets were placed in a conical ribbon vacuum dryer (Okawahara Manufacturing Co., Ltd., product name: Ribocone RM-10V) and thoroughly purged with nitrogen. Solid-state polymerization was carried out by heating the pellets at 210°C for 2 hours while stirring and flowing nitrogen at 1 L / min. The temperature was then lowered while still flowing nitrogen, and the pellets were removed from the dryer as they were when the temperature reached approximately 50°C. The obtained resin composition pellets were molded into ISO 3167 multipurpose test specimens type A using the same injection molding machine as in Example 1-1, with the mold temperature set to 80°C and the cylinder temperature set to 290°C. The molded specimens were used to evaluate various mechanical properties, vibration fatigue properties, wear properties, etc.

[0213] [Example 1-19] The pellets of the resin composition obtained in Example 1-8 were injection molded using an injection molding machine α50i-A (manufactured by Fanuc Corporation) under the following injection conditions: cylinder temperature 290°C, mold temperature 80°C, maximum injection pressure 120 MPa, injection time 10 seconds, and cooling time 60 seconds, to obtain a worm wheel gear with a module of 3.0, 50 teeth, tooth thickness 5 mm, and tooth width 15 mm. A gear durability test was conducted using the worm wheel gear.

[0214] [Examples 1-20, 1-21, Comparative Examples 1-7, 1-8] Worm wheel gears were molded from pellets of the resin compositions of Examples 1-11, 1-16, Comparative Examples 1-2 and 1-6 in the same manner as in Example 1-19, except that the resin compositions used were changed to pellets of the resin compositions listed in Table 7, and subjected to the respective tests.

[0215] [Measurement method] <Ignition loss of glass fiber (amount of surface treatment agent attached)> After precisely weighing 10 g of glass fiber, it was heated in an electric furnace at 650°C for 1 hour. The mass loss during this time was taken as the ignition loss of the glass fiber. This procedure was repeated 10 times with 10 g of each different glass fiber, and the average value M and standard deviation σ of the ignition loss were calculated.

[0216] <Formic Acid Relative Viscosity VR> The formic acid relative viscosity (VR) was obtained by comparing the viscosity of a solution (soluble matter) prepared by dissolving the fiber-reinforced polyamide resin compositions obtained in Examples and Comparative Examples in formic acid with the viscosity of formic acid itself. Specifically, the measurement was carried out in accordance with ASTM-D789. More specifically, the VR was measured at 25°C using a solution prepared by dissolving the soluble matter in the fiber-reinforced polyamide resin composition in 90% by mass of formic acid (10% by mass of water) at a ratio of 8.4% by mass.

[0217] <Quantitative determination of formic acid insoluble matter> The formic acid insoluble content of the polyamide resin compositions produced in Examples 1-1 to 1-18 and Comparative Examples 1-1 to 1-6 was determined as follows. First, the fiber-reinforced polyamide resin composition was placed in 90% by mass of formic acid (10% by mass of water), and the solution obtained by dissolving the composition while stirring overnight was filtered using a membrane filter with a pore size of 0.65 μm. The formic acid-insoluble matter remaining on the filter paper was separated, and the separated formic acid-insoluble matter was air-dried overnight to remove the residual solvent. The mass of the obtained dried product was measured, and the amount of the formic acid-insoluble matter was calculated using the following formula. Formic acid insoluble matter (mass%) = dry mass (g) / fiber-reinforced polyamide resin composition dissolved in formic acid (g) × 100 Furthermore, the ash content of the sample was measured in advance based on the standard of ISO3451-4, and the amount of formic acid insoluble matter relative to the ash content was calculated using the following formula. Formic acid insoluble content (mass %) relative to ash content = formic acid insoluble content (mass %) / ash content (mass %) × 100 Using the above method, the formic acid insoluble content and the ash content were measured 10 times each, and the average values ​​were calculated.

[0218] <Short GF ratio> The pellets of the glass fiber-reinforced polyamide resin compositions obtained in Examples 1-1 to 1-18 and Comparative Examples 1-1 to 1-6 were heated at 650°C for 2 hours to burn off and remove only the polyamide, and then observed using an optical microscope. The lengths of 400 arbitrarily selected reinforcing fibers were measured using an image analyzer, and the proportion of glass fibers of 250 μm or less was calculated.

[0219] <Unresolved number> After weighing 1 kg of the glass fiber reinforced polyamide resin composition pellets obtained in Examples 1-1 to 1-18 and Comparative Examples 1-1 to 1-6, pellets in which glass fiber bundles protruded by 0.5 mm or more from the pellet cross section were classified as undefibrated pellets, and the number of undefibrated pellets was counted. This operation was carried out 10 times with 1 kg of different pellets each time, and the average value was taken as the number of undefibrated pellets.

[0220] <Tensile test> Using the A-type test pieces obtained in Examples 1-1 to 1-18 and Comparative Examples 1-1 to 1-6, a tensile test was carried out in accordance with ISO527 at a test speed of 50 mm / min to measure the tensile strength (MPa). In addition, a total of 20 A-type test pieces were molded, and the tensile strength of each was measured. The coefficient of variation (CV) of the tensile strength was calculated using the following formula. 引張 ) was calculated. CV 引張 =(σ 引張 / μ 引張 ) x 100 where σ 引張 is the standard deviation of tensile strength, μ 引張 represents the arithmetic mean of the tensile strength.

[0221] <Vibration fatigue> The resin composition pellets obtained in Examples 1-1 to 1-18 and Comparative Examples 1-1 to 1-6 were injected into an injection molding machine PS-40E (manufactured by Nissei Plastics Co., Ltd.) with an injection and dwell time of 10 seconds, a mold temperature of 80°C, and a cylinder temperature of 290°C. JIS K7139 small ISO test pieces (3 mm thick) prepared in accordance with ISO294-1 were subjected to vibration fatigue testing using a Shimadzu Servo Pulser (EHF-FV1 OKN-1 OLA) manufactured by Shimadzu Corporation. The conditions were frequency: 20 Hz, waveform: sine wave, temperature: 120°C, stress ratio: 0.1, chuck distance: 30 mm, and stress applied to the sample: 60 MPa, and the number of vibrations until the sample broke was determined.

[0222] <Friction coefficient and wear depth> The A-type test pieces obtained in Examples 1-1 to 1-18 and Comparative Examples 1-1 to 1-6 were subjected to a sliding test using a reciprocating friction and wear tester (Model AFT-15MS, manufactured by Toyo Seimitsu Co., Ltd.) and a SUS304 test piece (5 mm diameter ball) as the counter material at a linear velocity of 30 mm / sec, a reciprocating distance of 20 mm, a temperature of 23°C, a humidity of 50%, a load of 1.5 kg, and 5,000 reciprocating cycles to obtain the coefficient of friction. The wear depth at the center of the wear mark on the sample after the sliding test was measured using a surface roughness tester (Model 575A-30, manufactured by Toyo Seimitsu Co., Ltd.). Tables 8 to 13 show the respective results as "friction coefficient (23°C)" and "wear depth (23°C)."

[0223] <Black spot foreign matter> The resin composition pellets obtained in Examples 1-1 to 1-18 and Comparative Examples 1-1 to 1-6 were injection molded using an injection molding machine (FN-3000, screw diameter 40 mm, manufactured by Nissei Plastic Industrial Co., Ltd.) under molding conditions of a cylinder temperature of 290°C, a mold temperature of 80°C, an injection pressure of 65 MPa, an injection time of 15 seconds, a cooling time of 15 seconds, and a screw rotation speed of 200 rpm to mold flat plates measuring 80 mm wide x 120 mm long x 8 mm thick, and the number of black spots was counted.

[0224] <Gear durability test> Tests were conducted using a gear durability testing machine manufactured by Toshiba Machine Co., Ltd. using the worm wheel gears obtained in Examples 1-19 to 1-21 and Comparative Examples 1-7 to 1-8. A SUS304 worm and a resin worm wheel gear were combined, with the worm wheel gear on the drive side and the worm on the driven side. Grease (Multemp CPL manufactured by Kyodo Yushi Co., Ltd.) was applied to the meshing area and rotated by hand to ensure that the grease was thoroughly spread throughout the worm and worm wheel gear. Next, the drive gear was rotated under the following conditions, and the number of rotations (endurance cycles) until the gear broke was measured. Test conditions: Temperature 23°C, humidity 50%, torque 25N / m, rotation speed 30rpm After each rotation in the forward and backward directions, a one-second interval was allowed before a rotation in the opposite direction was performed.

[0225] <Mass reduction rate after 100,000 rotations> The worm wheel gears obtained in Examples 1-9 to 1-21 and Comparative Examples 1-7 to 1-8 were subjected to 100,000 cycles (1.0 × 10 5 After rotating the worm wheel gear 10 times, the weight W1 of the worm wheel gear was measured, and the weight reduction rate (mass %) relative to the weight W0 before the test was calculated using the following formula. Weight reduction rate=[(W0-W1) / W0]×100

[0226] [Table 1]

[0227] [Table 2]

[0228] [Table 3]

[0229] [Table 4]

[0230] [Table 5]

[0231] [Table 6]

[0232] [Table 7]

[0233] [Table 8]

[0234] [Table 9]

[0235] [Table 10]

[0236] [Table 11]

[0237] [Table 12]

[0238] [Table 13]

[0239] The worm wheel gears of Examples 1-19 to 1-21, which satisfied the predetermined range, were provided with sufficient mechanical properties, reduced variations in properties, and good sliding properties. On the other hand, in the worm wheel gears of Comparative Examples 1-7 and 1-8, the molded articles were not provided with sufficient mechanical properties, and the variations in properties were not reduced and sliding properties were not imparted.

[0240] [Ingredients for each sample] (A2) Production of polyamide resin (Production Example 2-1: Production of Polyamide Resin A2-1 (Polyamide 66)) 15,000 g of an equimolar salt of adipic acid and hexamethylenediamine, and 0.5 mol% excess adipic acid relative to the equimolar salt components, were dissolved in 15,000 g of distilled water to obtain a 50% by mass aqueous solution of the raw material monomer. The resulting aqueous solution was charged into a 40 L autoclave, and the autoclave was purged with nitrogen. The aqueous solution was concentrated by gradually removing water vapor to a solution concentration of 70% by mass while stirring at a temperature of 110°C to 150°C. The internal temperature was then raised to 220°C. The autoclave was then pressurized to 1.8 MPa. The reaction was continued for 1 hour while gradually removing water vapor to maintain the pressure at 1.8 MPa until the internal temperature reached 270°C. The pressure was then reduced to atmospheric pressure over approximately 1 hour. After atmospheric pressure was reached, the mixture was discharged in the form of strands from the bottom nozzle, water-cooled, and cut to obtain pellets of polyamide resin A2-1. The obtained pellets were dried in a nitrogen stream at 90°C for 4 hours. The viscosity number RV of the pellets was 48 and the melting point was 265°C.

[0241] (Production Example 2-2: Production of Polyamide Resin A2-2 (Polyamide 66)) Before discharging from the bottom nozzle, the chamber was vacuumed to 100 torr (1.33 × 10 4 Pellets of polyamide resin A2-2 were produced in the same manner as in Production Example 2-1, except that the pressure was maintained at a reduced pressure of 1000 kJ / cm² (1000 kPa) for 5 minutes. The pellets had a viscosity number RV of 60 and a melting point of 264°C.

[0242] (Production Example 2-3: Production of Polyamide Resin A2-3 (Polyamide 66)) 10 kg of the pellets obtained in the above (Production Example 2-1) were placed in a conical ribbon vacuum dryer (manufactured by Okawara Manufacturing Co., Ltd., product name: Ribocone RM-10V) and nitrogen substitution was carried out by stirring while flowing nitrogen at 10 L / min. While continuing to flow nitrogen at 10 L / min and stirring, the pellets were heated at a pellet temperature of 215°C for 6 hours. Thereafter, the temperature was lowered while continuing to flow nitrogen, and when it reached approximately 50°C, the pellets were removed from the device as pellets. The pellets had a viscosity number RV of 260 and a melting point of 262°C.

[0243] (B2) Manufacturing of fibrous reinforcing materials (Production Example 2-4: Production of fibrous reinforcing material B2-1) First, (x2-1) to (x2-4) described below were diluted with water so that the solid content was 2 mass% polyurethane resin, 4 mass% maleic anhydride-butadiene copolymer, 0.6 mass% γ-aminopropyltriethoxysilane, and 0.1 mass% carnauba wax, to obtain a glass fiber sizing agent. The obtained glass fiber sizing agent was adhered to glass fibers having a number average fiber diameter of 7 μm. The adhesion method was a method in which the sizing agent was adhered to the glass fibers using an applicator installed midway as the melt-stripped glass fibers were wound onto a rotating drum. The glass fibers to which the sizing agent was adhered were then dried to obtain a roving of glass fiber bundles surface-treated with the glass fiber sizing agent. At this time, the glass fibers were arranged into bundles of 1,000 fibers. The amount of glass fiber sizing agent adhered to the glass fibers was 0.6 mass%. The obtained roving was cut to a length of 3 mm to obtain fibrous reinforcement B2-1 (chopped strands, hereinafter also abbreviated as "(B2-1)").

[0244] The components (x2-1) to (x2-4) constituting the sizing agent used in producing the above fibrous reinforcing material are as follows: (x2-1) Polyurethane resin emulsion Product name: Bondic (registered trademark) 1050 (manufactured by Dainippon Ink Co., Ltd.) (Aqueous solution with 50% solids by mass) (x2-2) Maleic anhydride copolymer emulsion Product name: Acrobinder (registered trademark) BG-7 (manufactured by Sanyo Chemical Industries, Ltd.) (aqueous solution with 25% solids by mass) (x2-3) Aminosilane coupling agent Product name: KBE-903 (Shin-Etsu Chemical Co., Ltd.) γ-aminopropyltriethoxysilane (x2-4) Lubricant Product name: Carnauba wax (manufactured by Kato Yoko Co., Ltd.)

[0245] (Production Example 2-5: Production of fibrous reinforcing material B2-2) A fibrous reinforcing material B2-2 (chopped strand, hereinafter also simply referred to as "(B2-2)") was obtained using the same method as in Production Example 2-4, except that glass fibers having a number average fiber diameter of 5 μm were used instead of glass fibers having a number average fiber diameter of 7 μm. The amount of glass fiber sizing agent attached to the glass fibers was 0.7 mass%.

[0246] (Production Example 2-6: Production of fibrous reinforcing material B2-3) A fibrous reinforcing material (B2-3) (chopped strands, hereinafter also simply referred to as "(B2-3)") was obtained in the same manner as in Production Example 2-4, except that glass fibers having a number average fiber diameter of 13 μm were used instead of glass fibers having a number average fiber diameter of 7 μm. The amount of glass fiber sizing agent attached to the glass fibers was 0.4 mass%.

[0247] [Other ingredients in each sample] In addition to the raw materials produced above, the following raw materials were also used. (C2) Copper compound Copper iodide: Copper(I) iodide, manufactured by Wako Pure Chemical Industries, Ltd. (D2) Metal halides Potassium iodide: Potassium iodide, manufactured by Wako Pure Chemical Industries, Ltd.

[0248] <Examples 2-1 to 2-7, Comparative Examples 2-1 to 2-2> Using the above-mentioned components, polyamide resin compositions of each sample were produced under the conditions shown below.

[0249] Example 2-1: Production of polyamide resin composition PA-a1 (1) Melt-kneading process Using a twin-screw extruder (manufactured by Coperion Co., Ltd., trade name "ZSK26MC") with a screw having a melting zone and a kneading zone, a mixture of polyamide resin A2-1 obtained in Production Example 2-1 impregnated with a copper compound and a halide was fed as a top feed according to the formulation shown in Table 14, and fibrous reinforcement B2-1 obtained in Production Example 2-4 was fed as a side feed. Melt-kneading was carried out under extrusion conditions of a set temperature of 290 °C, a screw rotation speed of 300 rpm, and a throughput of 29 kg / h. The pellets were cooled to the water immersion length shown in Table 14 and cut with a strand cutter to obtain pellets. The resulting pellets had an elliptical cylindrical shape, and the pellet length, major axis a, minor axis b, and ratio a / b are shown in Table 17. (2)Heating process (solid phase polymerization) 11 kg of pellets obtained in the melt-kneading step (1) above were placed in a conical ribbon vacuum dryer (Okawahara Manufacturing Co., Ltd., product name: Ribocone RM-10V) and stirred while flowing nitrogen at 10 L / min to perform nitrogen substitution (oxygen concentration 3.1 ppm, moisture concentration 8.3 ppm). While continuing to flow nitrogen at 10 L / min and stirring, the pellets were heated at a temperature of 210°C for 5 hours. Thereafter, the temperature was lowered while still flowing nitrogen, and when it reached approximately 50°C, the pellets were removed from the dryer as pellets, yielding pellets of polyamide resin composition PA-a1. The viscosity number RV of the resulting pellets was 177.

[0250] [Example 2-2: Production of polyamide resin composition PA-a2] Melt mixing and solid-state polymerization were carried out in the same manner as in Example 2-1, except that the immersion length of the strand in water was shortened, to obtain pellets of polyamide resin composition PA-a2. The pellet length, major axis a, minor axis b, and ratio a / b after melt mixing are shown in Table 17. The viscosity number RV of the obtained pellets after solid-state polymerization was 184.

[0251] Example 2-3: Production of polyamide resin composition PA-a3 Melt kneading and solid-state polymerization were carried out in the same manner as in Example 2-1, except that polyamide resin A2-2 obtained in Production Example 2-2 was used instead of polyamide resin A2-1 obtained in Production Example 2-1, to obtain pellets of polyamide resin composition PA-a3. The pellet length, major axis a, minor axis b, and ratio a / b after melt kneading are shown in Table 17. The viscosity number RV of the obtained pellets after solid-state polymerization was 185.

[0252] [Example 2-4: Production of polyamide resin composition PA-a4] Melt mixing and solid-state polymerization were carried out in the same manner as in Example 2-1, except that the amount of fibrous reinforcing material B2-1 was reduced to the amount shown in Table 14, to obtain pellets of polyamide resin composition PA-a4. The length, major axis a, minor axis b, and ratio a / b of the pellets after melt mixing are shown in Table 17. The viscosity number RV of the obtained pellets after solid-state polymerization was 180.

[0253] [Example 2-5: Production of polyamide resin composition PA-a5] Melt mixing and solid-state polymerization were carried out in the same manner as in Example 2-1, except that the amount of fibrous reinforcing material B2-1 was increased to the amount shown in Table 15, to obtain pellets of polyamide resin composition PA-a5. The length, major axis a, minor axis b, and ratio a / b of the pellets after melt mixing are shown in Table 18. The viscosity number RV of the obtained pellets after solid-state polymerization was 176.

[0254] [Example 2-6: Production of polyamide resin composition PA-a6] Melt mixing and solid-state polymerization were carried out in the same manner as in Example 2-1, except that fibrous reinforcing material B2-2 was used instead of fibrous reinforcing material B2-1, to obtain pellets of polyamide resin composition PA-a6. The pellet length, major axis a, minor axis b, and ratio a / b after melt mixing are shown in Table 18. The viscosity number RV of the obtained pellets after solid-state polymerization was 178.

[0255] [Example 2-7: Production of polyamide resin composition PA-a7] Melt mixing and solid-state polymerization were carried out in the same manner as in Example 2-1, except that fibrous reinforcing material B2-3 was used instead of fibrous reinforcing material B2-1, to obtain pellets of polyamide resin composition PA-a7. The pellet length, major axis a, minor axis b, and ratio a / b after melt mixing are shown in Table 18. The viscosity number RV of the obtained pellets after solid-state polymerization was 177.

[0256] Comparative Example 2-1: Production of polyamide resin composition PA-b1 Melt mixing and solid-state polymerization were carried out in the same manner as in Example 2-1, except that the immersion length of the strand in water was increased, to obtain pellets of polyamide resin composition PA-b1. The pellet length, major axis a, minor axis b, and ratio a / b after melt mixing are shown in Table 19. The viscosity number RV of the obtained pellets after solid-state polymerization was 170.

[0257] Comparative Example 2-2: Production of polyamide resin composition PA-b2 Instead of the polyamide resin A2-1 obtained in Production Example 2-1, the polyamide resin A2-3 obtained in Production Example 2-3 was used. A mixture containing a copper compound and a halide was top-fed according to the formulation shown in Table 16, and the fibrous reinforcement B2-1 obtained in Production Example 2-4 was side-fed. Melt-kneading was carried out under extrusion conditions of a set temperature of 310°C, a screw speed of 200 rpm, and a throughput of 15 kg / h. The extrusion was cooled to the water immersion length shown in Table 16 and cut with a strand cutter to obtain pellets of polyamide resin composition PA-b2. The pellets obtained were elliptical cylinders, and their length, major axis a, minor axis b, and ratio a / b are shown in Table 19. The viscosity number RV of the resulting pellets was 180.

[0258] <Evaluation> The polyamide resin compositions of the samples obtained by the above method were evaluated as follows. The evaluation results are shown in Tables 17 to 19. (1) Pellet shape The major axis a, minor axis b, and pellet length of 100 pellets of the polyamide resin composition obtained in the Examples and Comparative Examples were measured with an electronic caliper, and the average values ​​were taken as the major axis a, minor axis b, and pellet length. In addition, the ratio a / b of the major axis a to the minor axis b of the pellet cross section was calculated.

[0259] (2) Viscosity number RV The relative viscosity RV of the polyamide resin compositions obtained in the examples and comparative examples was measured in accordance with ASTM D 789. More specifically, the RV value measured at 25°C using a solution prepared by dissolving polyamide in 90% by mass of formic acid (10% by mass of water) to a concentration of 8.4% by mass was used.

[0260] (3)Molecular weight The proportion (%) of components having a molecular weight of 10,000 or less and the proportion (%) of components having a molecular weight of 250,000 or more in the polyamide resin compositions obtained in the Examples and Comparative Examples were calculated from the molecular weight distribution measured by gel permeation chromatography (GPC) as follows. Apparatus: Tosoh Corporation, "HLC-8320GPC" Detector: Differential refractometer (RI) Solvent: hexafluoroisopropanol (HFIP) containing 0.1 mol% sodium trifluoroacetate Columns: Two "TSKgel-GMHHR-M" columns and one "G1000HHR" column, manufactured by Tosoh Corporation, were connected in series. Calculations were made based on the elution curve obtained and converted into polymethyl methacrylate (PMMA) equivalents.

[0261] (4) Molar ratio of carboxyl end groups to amino end groups The amount of carboxyl terminal group [COOH] and the amount of amino terminal group [NH2] of the polyamide resin compositions obtained in the examples and comparative examples were calculated as follows: 1 The amount of terminal groups present in 1 kg of polyamide resin was calculated using H-NMR (sulfuric acid-d2 solvent). The specific procedure is shown below. Carboxy group terminal: Calculated from the integral value of the peak (a') at 2.724 ppm for the hydrogen of the methylene group (-CH2-) adjacent to the terminal COOH. Amino group terminal: Calculated from the integral value of the peak (b') near 2.884 ppm for the hydrogen of the methylene group (-CH2-) adjacent to the terminal NH2. Dicarboxylic acid units in the polyamide main chain: Calculated from the integral value of peak (a) at 2.451 ppm for the hydrogen of the methylene group (-CH2-) adjacent to the amide group. Diamine unit in the polyamide main chain: Calculated from the integral value of peak (b) at 3.254 ppm for the hydrogen of the methylene group (-CH2-) adjacent to the amide group. Using the integral values ​​of the above peaks, the amount of carboxyl terminal group [COOH] and the amount of amino terminal group [NH2] were calculated using the following formula. Carboxy end group amount [COOH] (mmolEq / kg) =(a' / 2) / [{(b+b')×114.2 / 4}+{(a+a')×112.1 / 4}] Amino end group amount [NH2] (mmolEq / kg) =(b' / 2) / [{(b+b')×114.2 / 4}+{(a+a')×112.1 / 4}] Then, the molar ratio of the amount of carboxyl terminal groups to the amount of amino terminal groups, [NH2] / [COOH], was calculated from the amount of carboxyl terminal groups [COOH] and the amount of amino terminal groups [NH2] obtained.

[0262] [Table 14]

[0263] [Table 15]

[0264] [Table 16]

[0265] [Table 17]

[0266] [Table 18]

[0267] [Table 19]

[0268] The results in Tables 17 to 19 show that in the polyamide resin compositions PA-a1 to PA-a7 (Examples 2-1 to 2-7), the high molecular weight components increased and the viscosity number RV value also increased, even though the heating step (solid-state polymerization) time was kept constant. By performing the heating step (solid-state polymerization) using elliptical cylindrical pellets, it is clear that the molecular weight distribution is efficiently shifted to the high molecular weight side, making it possible to shorten the heating step (solid-state polymerization) time.

[0269] <Methods for measuring physical properties> [Physical Properties 3-1] (viscosity number VN) The viscosity number VN was measured according to ISO307 (JIS-K6933) using pellets of polyamide, molten mixture, and thermoplastic resin composition. Specifically, the measurement was performed on a solution of polyamide, molten mixture, or thermoplastic resin composition at a concentration of 0.5% by mass in 96% by mass sulfuric acid at 25°C. When the sample contained a reinforcing material such as glass fiber, the ash content of the sample was measured in advance, for example, according to the provisions of ISO3451-4, and the content of polyamide resin in the sample was calculated using the content of polyamide resin after subtracting the ash content.

[0270] [Physical Properties 3-2] (Moisture percentage) The moisture content (mass%) of the pellets of the melt-kneaded products produced in the examples and comparative examples was measured using a Karl Fischer moisture meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., coulometric titration type trace moisture analyzer CA-200 model) according to a method conforming to ISO15512.

[0271] [Physical Properties 3-3] (Melting Point) The heat of fusion was measured using a Diamond-DSC manufactured by Perkin-Elmer in accordance with JIS-K7121 (hereinafter also referred to as "DSC measurement"). The DSC measurement was performed under a nitrogen atmosphere. Approximately 10 mg of polyamide 66 pellets produced in Production Examples 3-1 and 3-2 were used as samples. Specifically, in the DSC measurement, the sample was first heated from 25°C to the melting point of the polyamide + approximately 30°C (e.g., 294°C for PA66) at a heating rate of 20°C / min. Next, the polyamide was completely melted by maintaining the maximum temperature of the first heating for 3 minutes. Thereafter, the sample was cooled to 25°C at a cooling rate of 20°C / min and maintained at 25°C for 3 minutes. The melting point of polyamide 66 was then determined from the endothermic peak (melting peak) that appeared when the sample was heated again at a heating rate of 20°C / min.

[0272] [Physical Properties 3-4] (weight average fiber length of glass fiber) The weight-average fiber length of the glass fibers contained in the polyamide resin composition after the heating step was calculated using the method described below. 1 g of the polyamide resin composition after the heating step was placed in a porcelain crucible, and the resin composition was burned and removed using an electric muffle furnace (Yamato Scientific FP-31 model, set temperature 600°C). The glass fibers remaining after the burning were transferred onto a slide glass and observed under an optical microscope. The lengths of 400 arbitrarily selected glass fibers were measured using an image analyzer, and the total value was divided by the total mass of the glass fibers to calculate the weight-average fiber length.

[0273] <Evaluation method> [Preparation of test specimens] Using the thermoplastic resin composition pellets produced in the Examples and Comparative Examples, small tensile test specimens (Type CP13) (3 mm thick) were produced using an injection molding machine in accordance with JIS-K7139 as follows. The injection molding machine used was a PS40E manufactured by Nissei Plastic Industrial Co., Ltd., equipped with a two-cavity mold for the small tensile test specimens. The cylinder temperature was set to the melting point of the polyamide plus approximately 15°C (e.g., 280°C for PA66), and the mold temperature was set to 80°C. Furthermore, small dumbbell-shaped tensile test specimens were obtained from the thermoplastic resin composition pellets under injection molding conditions of 10 seconds for injection, 7 seconds for cooling, and a plasticization volume of 30 mm (cushion volume of approximately 10 mm).

[0274] [Rating 3-1] (Color of pellets and molded products) The L value, a value, and b value were measured by reflection using a color difference meter ZE2000 manufactured by Nippon Denshoku Industries Co., Ltd., and the yellowness was determined by the b value. The larger the absolute value of the b value (-), the whiter and better the color tone, and the larger the absolute value (+), the more yellow coloring has occurred.

[0275] [Rating 3-2] (Vibration fatigue resistance) The obtained small tensile test specimens (type CP13) (3 mm thick) were subjected to a hydraulic servo fatigue testing machine (product name: EHF-50-10-3, manufactured by Saginomiya Seisakusho Co., Ltd.) in accordance with JIS K7118, and the number of vibrations (cycles) at which the test specimens broke was determined under conditions of a temperature of 120°C, a sine wave with a frequency of 20 Hz, and a tensile load of 60 MPa. The evaluation criteria are as follows: the more vibrations there are until breakage (the more vibrations there are 15 x 10 5 times or more), it was evaluated as having excellent vibration fatigue resistance.

[0276] [Productivity evaluation: Evaluation of abnormal noise during solid-state polymerization] During solid-state polymerization operation, 10 people checked for the occurrence of squealing and abnormal noises and rated them as follows: If no one judges that squealing or abnormal noise has occurred: ○ (Good) If the number of people who judged that squealing or abnormal noise occurred was between 1 and 2: △ (poor) If three or more people judge that squealing or abnormal noise has occurred: × (very poor)

[0277] <Raw materials> 1. (A3) Component: Production of Polyamide [Manufacturing Example 3-1] (Production of Polyamide A3-1: Polyamide 66) 15,000 g of an equimolar salt of adipic acid and hexamethylenediamine, and a 0.5 mol% excess of adipic acid relative to the equimolar salt components, were dissolved in 15,000 g of distilled water to obtain a 50% by mass aqueous solution of the raw material monomer. The resulting aqueous solution was charged into a 40 L autoclave, and the autoclave was purged with nitrogen. The aqueous solution was concentrated by gradually removing steam to a solution concentration of 70% by mass while stirring at a temperature of 110°C to 150°C. The internal temperature was then raised to 220°C. The autoclave was then pressurized to 1.8 MPa. The reaction was continued for 1 hour while gradually removing steam to maintain the pressure at 1.8 MPa until the internal temperature reached 270°C. The pressure was then reduced to atmospheric pressure over approximately 1 hour. After atmospheric pressure was reached, the mixture was discharged in the form of strands from the bottom nozzle, water-cooled, and cut to obtain pellets of polyamide A3-1. The obtained pellets were dried in a nitrogen stream at 90°C for 4 hours. The viscosity number VN of the pellets was 133 and the melting point was 265°C.

[0278] [Manufacturing Example 3-2] (Production of Polyamide A3-2: Polyamide 66) Before discharging from the bottom nozzle, the chamber was vacuumed to 100 torr (1.33 × 10 4 Pellets of polyamide A3-2 were produced in the same manner as in Production Example 3-1, except that the pressure was maintained at a reduced pressure of 100 Pa for 10 minutes. The viscosity number VN of the pellets was 182 and the melting point was 264°C.

[0279] 2. (B3) Component: Glass Fiber Manufacturing [Manufacturing Example 3-3] (Production of glass fiber B3-1) First, (x3-1) to (x3-4) described below were diluted with water in proportions such that the solid content was 2 mass% polyurethane resin, 4 mass% maleic anhydride-butadiene copolymer, 0.6 mass% γ-aminopropyltriethoxysilane, and 0.1 mass% carnauba wax, to obtain a glass fiber sizing agent. The obtained glass fiber sizing agent was adhered to glass fibers (containing boron oxide) having a number average fiber diameter of 7 μm. The adhesion method was a method in which the sizing agent was adhered to the glass fibers using an applicator installed midway as the melt-blocked glass fibers were wound around a rotating drum. The glass fibers to which the sizing agent was adhered were then dried to obtain a roving of glass fiber bundles surface-treated with the glass fiber sizing agent. At this time, the glass fibers were bundled into a bundle of 1,000 fibers. The amount of glass fiber sizing agent adhered to the glass fibers was 0.6 mass%. The obtained roving was cut to a length of 3 mm to obtain glass fiber B3-1 (chopped strands, hereinafter also abbreviated as "(B3-1)").

[0280] The components (x3-1) to (x3-4) constituting the sizing agent used in producing the fibrous reinforcing material are as follows: (x3-1) Polyurethane resin emulsion Product name: Bondic (registered trademark) 1050 (manufactured by Dainippon Ink Co., Ltd.) (Aqueous solution with 50% solids by mass) (x3-2) Maleic anhydride copolymer emulsion Product name: Acrobinder (registered trademark) BG-7 (manufactured by Sanyo Chemical Industries, Ltd.) (aqueous solution with 25% solids by mass) (x3-3) Aminosilane coupling agent Product name: KBE-903 (Shin-Etsu Chemical Co., Ltd.) γ-aminopropyltriethoxysilane (x3-4) Lubricant Product name: Carnauba wax (manufactured by Kato Yoko Co., Ltd.)

[0281] [Manufacturing Example 3-4] (Production of glass fiber B3-2) Glass fiber B3-2 (chopped strands, hereinafter also simply referred to as "(B3-2)") was obtained using the same method as in Production Example 3-3 above, except that glass fiber (containing boron oxide) having a number average fiber diameter of 5 μm was used instead of glass fiber (containing boron oxide) having a number average fiber diameter of 7 μm. The amount of glass fiber sizing agent attached to the glass fiber was 0.7 mass%.

[0282] [Manufacturing Example 3-5] (Manufacture of glass fiber B3-3) Glass fiber B3-3 (chopped strand, hereinafter also simply referred to as "(B3-3)") was obtained using the same method as in Production Example 3-3 above, except that glass fiber (boron oxide-free) having a number average fiber diameter of 7 μm was used instead of glass fiber (boron oxide-containing) having a number average fiber diameter of 7 μm. The amount of glass fiber sizing agent attached to the glass fiber was 0.6 mass%.

[0283] [Manufacturing Example 3-6] (Manufacture of glass fiber B3-4) Glass fiber B3-4 (chopped strand, hereinafter also simply referred to as "(B3-4)") was obtained in the same manner as in Production Example 3-3, except that glass fiber (containing boron oxide) having a number average fiber diameter of 10 μm was used instead of glass fiber (containing boron oxide) having a number average fiber diameter of 7 μm. The amount of glass fiber sizing agent attached to the glass fiber was 0.5 mass%.

[0284] 3. Other raw materials In addition to the raw materials produced above, the following raw materials were also used. (C3) Component: Copper compound Copper iodide: Copper(I) iodide, manufactured by Wako Pure Chemical Industries, Ltd. (D3) Component: Metal halide Potassium iodide: Potassium iodide, manufactured by Wako Pure Chemical Industries, Ltd.

[0285] <Production of Thermoplastic Resin Composition> [Example 3-1] (Production of thermoplastic resin composition PA-a8) (1) Melt-kneading process Using a twin-screw extruder with a screw diameter of 26 mm (manufactured by Coperion Co., Ltd., product name "ZSK26MC"), a mixture of polyamide A3-1 obtained in Production Example 3-1 impregnated with a copper compound and a metal halide was fed as a top feed according to the formulation shown in Table 20, and glass fiber B3-1 obtained in Production Example 3-3 was fed as a side feed. Melt-kneading was carried out under extrusion conditions of a set temperature of 290 ° C, a screw rotation speed of 300 rpm, and a discharge rate of 25 kg / h, and melt-kneaded pellets were obtained by the strand cut method. The VN and moisture content of the obtained melt-kneaded pellets were as shown in Table 25.

[0286] (2)Heating process (solid phase polymerization) 10 kg of the pellets obtained in the "(1) melt-kneading step" were placed in a conical ribbon vacuum dryer (Okawahara Manufacturing Co., Ltd., product name: Ribocone RM-10V) with stirring, and the atmosphere was thoroughly purged with nitrogen (oxygen concentration: 4.2 ppm). With nitrogen flowing at 2 L / min and stirring, the pellets were heated at 190°C for 6 hours. The temperature was then lowered while still flowing nitrogen, and when it reached approximately 50°C, the pellets were removed from the device as pellets, yielding pellets of thermoplastic resin composition PA-a8. The VN of the resulting pellets was as shown in Table 25.

[0287] [Example 3-2] (Production of thermoplastic resin composition PA-a9) Using the pellets (melt-kneaded product) obtained in "(1) Melt-kneading step" of Example 3-1, 10 g of water was added, and the pellets were heated at a temperature of 190°C for 6 hours. Solid-state polymerization was carried out in the same manner as in Example 3-1 to obtain pellets of thermoplastic resin composition PA-a9. The VN of the obtained pellets is shown in Table 25.

[0288] [Example 3-3] (Production of thermoplastic resin composition PA-a10) Using the pellets (melt-kneaded product) obtained in "(1) Melt-kneading step" of Example 3-1, solid-state polymerization was carried out in the same manner as in Example 3-1, except that 80 g of water was added and heating was carried out at a pellet temperature of 190°C for 6 hours, thereby obtaining pellets of thermoplastic resin composition PA-a10. The VN of the obtained pellets is as shown in Table 25.

[0289] [Example 3-4] (Production of thermoplastic resin composition PA-a11) The pellets (melt-kneaded product) obtained in "(1) Melt-kneading step" of Example 3-1 were allowed to stand for 5 days under conditions of room temperature 23°C and humidity 60% to absorb water. The moisture content after water absorption was 0.5 wt%. Solid-state polymerization was carried out using the water-absorbed pellets in the same manner as in Example 3-1, except that the pellets were heated at a pellet temperature of 190°C for 6 hours, to obtain pellets of thermoplastic resin composition PA-a10. The VN of the obtained pellets is as shown in Table 25.

[0290] [Examples 3-5] (Production of thermoplastic resin composition PA-a12) Using the pellets (melt-kneaded product) obtained in "(1) Melt-kneading step" of Example 3-1, solid-state polymerization was carried out in the same manner as in Example 3-1, except that 50 g of water was added and heating was carried out at a pellet temperature of 210°C for 9 hours, thereby obtaining pellets of thermoplastic resin composition PA-a12. The VN of the obtained pellets is shown in Table 26.

[0291] [Examples 3-6 to 3-9] (Production of Thermoplastic Resin Compositions PA-a13 to 16) Melt kneading was carried out in the same manner as in Example 3-1, except that the blending compositions in "(1) Melt kneading step" of Example 3-1 were changed to those shown in Tables 21 and 22. The VN and moisture content of the obtained pellets were as shown in Tables 26 and 27. Solid-state polymerization was then carried out in the same manner as in Example 3-1, to obtain pellets of thermoplastic resin compositions PA-a13 to 16. The VN of the obtained pellets was as shown in Tables 26 to 27. In the thermoplastic resin composition of Example 3-9, the mass proportion of boron oxide was 0 mass % relative to 100 mass % of the thermoplastic resin composition.

[0292] [Example 3-10] (Production of thermoplastic resin composition PA-a17) Melt kneading was carried out in the same manner as in Example 3-1, except that the blending composition in "(1) Melt kneading step" of Example 3-1 was changed to that shown in Table 22. The VN and moisture content of the obtained pellets were as shown in Table 27. Next, solid-state polymerization was carried out in the same manner as in Example 3-1, except that the pellets were heated at a temperature of 190°C for 3 hours, to obtain pellets of thermoplastic resin composition PA-a17. The VN of the obtained pellets was as shown in Table 27.

[0293] [Comparative Example 3-1] (Production of Thermoplastic Resin Composition PA-b3) Using the pellets (melt-kneaded product) obtained in "(1) Melt-kneading step" of Example 3-1, solid-state polymerization was carried out in the same manner as in Example 3-1, except that water was not added and the pellets were heated at a pellet temperature of 190°C for 6 hours, thereby obtaining pellets of polyamide resin composition PA-b3. The VN of the obtained pellets is shown in Table 28.

[0294] [Comparative Example 3-2] (Production of thermoplastic resin composition PA-b4) Using the pellets (melt-kneaded product) obtained in "(1) Melt-kneading step" of Example 3-1, solid-state polymerization was carried out in the same manner as in Example 3-1, except that 1 g of water was added and the pellets were heated at a pellet temperature of 190°C for 6 hours, thereby obtaining pellets of thermoplastic resin composition PA-b4. The VN of the obtained pellets is shown in Table 28.

[0295] [Comparative Examples 3-3 to 3-4] (Production of Thermoplastic Resin Compositions PA-b5 to PA-b6) Melt kneading was carried out in the same manner as in Example 3-1, except that the blending composition in "(1) Melt kneading step" of Example 3-1 was changed to that shown in Table 23. The VN and moisture content of the obtained pellets were as shown in Table 28. Next, solid-state polymerization was carried out in the same manner as in Example 3-1, to obtain pellets of thermoplastic resin compositions PA-b5 to 6. The VN of the obtained pellets was as shown in Table 28.

[0296] [Comparative Example 3-5] (Production of thermoplastic resin composition PA-b7) Melt-kneading was carried out in the same manner as in Example 3-1, except that the blending composition in "(1) Melt-kneading step" of Example 3-1 was changed to that shown in Table 24. However, cuttability in the strand-cutting method was poor, and pellets could not be obtained. Therefore, the subsequent heating step (solid-state polymerization) was not carried out.

[0297] [Comparative Example 3-6] (Production of thermoplastic resin composition PA-b8) Melt kneading was carried out in the same manner as in Example 3-1, except that the blending composition in "(1) melt kneading step" of Example 3-1 was changed to that shown in Table 24. The VN and moisture content of the obtained pellets were as shown in Table 29. Next, solid-state polymerization was carried out in the same manner as in Example 3-1, except that heating was carried out at a pellet temperature of 190°C for 6 hours without adding water, to obtain pellets of thermoplastic resin composition PA-b8. The VN of the obtained pellets was as shown in Table 29.

[0298] [Comparative Example 3-7] (Production of thermoplastic resin composition PA-b9) Melt kneading was carried out in the same manner as in Example 3-1, except that the blending composition in "(1) Melt kneading step" of Example 3-1 was changed to that shown in Table 24. The VN and moisture content of the obtained pellets were as shown in Table 29. Next, solid-state polymerization was carried out in the same manner as in Example 3-1, to obtain pellets of thermoplastic resin composition PA-b9. The VN of the obtained pellets was as shown in Table 29.

[0299] [Table 20]

[0300] [Table 21]

[0301] [Table 22]

[0302] [Table 23]

[0303] [Table 24]

[0304] [Table 25]

[0305] [Table 26]

[0306] [Table 27]

[0307] [Table 28]

[0308] [Table 29]

[0309] As can be seen from Table 1, the polyamide resin compositions PA-a8 to PA-a17 (Examples 3-1 to 3-10) were good in all evaluation items. [Industrial Applicability]

[0310] The fiber-reinforced polyamide resin composition of the first embodiment and the molded article of the second embodiment of the present invention have excellent mechanical properties, reduced variations in properties, and excellent wear properties, and therefore have industrial applicability in the fields of automobiles, electricity and electronics, machinery and industry, office equipment, aviation and space, etc. According to the method for producing a thermoplastic resin composition of the third embodiment of the present invention, a thermoplastic resin composition having excellent physical properties and low production costs can be obtained. The thermoplastic resin composition obtained by the present invention is suitable for use in, for example, automobile parts, electronic and electrical parts, industrial machine parts, various gears, etc. According to the method for producing a thermoplastic resin composition of the fourth embodiment of the present invention, a thermoplastic resin composition having excellent color tone and vibration fatigue resistance can be obtained. The thermoplastic resin composition obtained by the present invention is suitable for use in, for example, automobile parts, electronic and electrical parts, industrial machine parts, various gears, etc.

Claims

1. a melt-kneading step of adding 5 parts by mass or more and 100 parts by mass or less of glass fibers having an average fiber diameter of 3 μm or more and 15 μm or less to 100 parts by mass of a thermoplastic resin having a viscosity number RV of 25 or more and 70 or less, and melt-kneading the mixture to obtain a melt-kneaded product; and a heating step of heating the melt-kneaded mixture at a temperature T represented by the following general formula (I) to obtain a thermoplastic resin composition, the melt-kneaded product is an elliptical cylindrical pellet having an elliptical cylindrical shape, and a ratio a / b of a major axis a to a minor axis b in a cross section of the elliptical cylindrical pellet is 1.3 to 3.0; The method for producing a thermoplastic resin composition, wherein the heating step comprises heating the elliptical cylindrical pellets while stirring them. Tm-130℃≦T≦Tm-10℃ (I) (In the formula, Tm is the melting point of the thermoplastic resin.)

2. The method for producing a thermoplastic resin composition according to claim 1, wherein the viscosity number RV of the thermoplastic resin composition is 70 or more and 400 or less.

3. The method for producing a thermoplastic resin composition according to claim 1 or 2, wherein the heating step comprises heating at the temperature T for 30 minutes or more and 15 hours or less.

4. 3. The method for producing a thermoplastic resin composition according to claim 1, wherein the thermoplastic resin is a polyamide or a polyester.

5. 5. The method for producing a thermoplastic resin composition according to claim 4, wherein the polyamide is at least one selected from the group consisting of polyamide 6, polyamide 66, polyamide 46, polyamide 610, and polyamide 612.

6. The method for producing a thermoplastic resin composition according to claim 1 or 2, wherein the heating step is performed at the temperature T in an inert gas atmosphere having an oxygen concentration of 5 ppm or less.

7. 3. The method for producing a thermoplastic resin composition according to claim 1, wherein the heating step is performed at the temperature T in an inert gas atmosphere having a moisture concentration of 10 ppm or less.

8. a melt-kneading step of adding 5 parts by mass or more and 100 parts by mass or less of glass fibers having an average fiber diameter of 3 μm or more and 9 μm or less to 100 parts by mass of a thermoplastic resin having a viscosity number VN of 80 or more and 200 or less, and melt-kneading the mixture to obtain a melt-kneaded product; a heating step of heating the melt-kneaded product at a temperature T represented by the following mathematical formula (I) to obtain a thermoplastic resin composition, A method for producing a thermoplastic resin composition, wherein the heating step contains 0.05 to 1.0 mass% of water relative to 100 mass% of the melt-kneaded product obtained in the melt-kneading step. Tm-130℃≦T≦Tm-10℃ (I) (In the formula, Tm is the melting point of the thermoplastic resin.)

9. The method for producing a thermoplastic resin composition according to claim 8, wherein the thermoplastic resin composition has a viscosity number VN of 200 or more and 350 or less.

10. The method for producing a thermoplastic resin composition according to claim 8 or 9, wherein the average fiber length of the glass fibers contained in the thermoplastic resin composition after the heating step is 100 μm or more and 1000 μm or less.

11. The method for producing a thermoplastic resin composition according to claim 8 or 9, wherein the glass fibers have an average fiber diameter of 4 μm or more and 8 μm or less.

12. The method for producing a thermoplastic resin composition according to claim 8 or 9, wherein in the heating step, heating at the temperature T is performed for 30 minutes or more and 15 hours or less.

13. The method for producing a thermoplastic resin composition according to claim 8 or 9, wherein in the heating step, heating at the temperature T is performed in an inert gas atmosphere having an oxygen concentration of 5 ppm or less.

14. The method for producing a thermoplastic resin composition according to claim 8 or 9, wherein the thermoplastic resin is a polyamide or a polyester.

15. The method for producing a thermoplastic resin composition according to claim 14, wherein the polyamide is polyamide 6, polyamide 66, or polyamide 610.

16. The method for producing a thermoplastic resin composition according to claim 8 or 9, wherein the thermoplastic resin composition is substantially free of boron oxide.

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