Method for manufacturing thermoplastic resin compositions

Abstract

The objective is to provide a method for producing a thermoplastic resin composition that exhibits excellent fiber-opening properties for fibrous fillers and good tensile strength stability. [Solution] A method for producing a thermoplastic resin composition containing a fibrous filler, characterized in that a thermoplastic resin is melted, a bundle of fibrous fillers is supplied and melt-kneaded, and the melt-kneading process includes a distribution step of distributing the bundle of fibrous fillers into the thermoplastic resin and a dispersion step of dispersing the bundle of fibrous fillers into the thermoplastic resin.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a thermoplastic resin composition. [Background Art]

[0002] Polyamide resins exhibit excellent properties as engineering plastics, and are therefore used in the manufacture of various types of machinery and components, such as the manufacture of automobiles, machinery, electrical and electronic components. Polyamide resins are particularly excellent in mechanical properties and wear resistance, and thus are widely used as molding materials for sliding components such as gears, cams, and bearings.

[0003] In recent years, as demand for higher performance of various machinery and components has increased, improvements have been made to enhance the mechanical properties of polyamide resin molded articles or the molding properties of polyamide resins by blending various fillers into the polyamide resin. Examples of such fillers include tetrafluoroethylene resin particles as a lubricant, glass fibers as a reinforcing material, and the like. In particular, fibrous fillers such as glass fibers are used as chopped strands, which are obtained by bundling a large number of fibers, consolidating them with a sizing agent, cutting the bundle, and then kneading the chopped strands with a resin or the like. However, when kneading with a thermoplastic resin, chopped strands may be discharged from an extruder without being opened, and it has been confirmed that unopened chopped strands (i.e., unopened fibrous filler) are present in pellets. Molded articles molded from pellets containing unopened fibrous filler have unstable strength and the like, therefore, reduction of unopened fibrous filler in the thermoplastic resin composition is desired. In particular, it is known that unopened fibrous filler is likely to occur in large extruders used as production machines.

[0004] Various reports have been made on the reduction of unopened fibrous filler. Patent Document 1 describes a method for producing glass fiber reinforced thermoplastic resin composition pellets, which involves controlling the minimum value of the time integral of the shear stress received by the glass fiber bundle during mixing and kneading (minimum shear stress hysteresis value Tmin) to determine the manufacturing conditions and suppress the unopening of glass fibers. Patent Document 2 describes a manufacturing method for supplying and melt-kneading a bundle of thermoplastic resin and fibrous filler, wherein the kneading zone has two or more reverse-feed screw elements and two or more forward-feed screw elements, and the reverse-feed screw elements and forward-feed screw elements are arranged alternately along the axial direction of the screw in an adjacent state, thereby suppressing the unopened fibers of glass fibers. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-45865 [Patent Document 2] International Publication No. 2023 / 058647 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the methods for producing thermoplastic resin compositions described in Patent Documents 1 and 2 do not take into consideration the amount of fibrous filler and the fiber diameter, and the methods described in Patent Documents 1 and 2 are insufficient.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a method for producing a thermoplastic resin composition that exhibits excellent fiber-opening properties of fibrous fillers and good stability of tensile strength (small coefficient of variation of tensile strength) of the resulting thermoplastic resin composition. [Means for solving the problem]

[0008] The inventors diligently conducted research to solve the above problems. As a result, they found that the generation of unopened fibrous filler material occurs not only when the extruder size is increased, but also when the amount of fibrous filler material is reduced, the fiber diameter is made smaller, and the melt viscosity of the resin is lowered. They then found that the following manufacturing method can suppress the generation of unopened fibrous filler material and solve the above problems, thus completing the present invention. In other words, the present invention includes the following embodiments.

[0009] [1] A method for producing a thermoplastic resin composition containing a fibrous filler, After melting the thermoplastic resin, a bundle of fibrous filler material is supplied and melt-kneaded, A method for producing a thermoplastic resin composition, characterized in that the melt kneading process includes a distribution step of distributing the fibrous filler bundle into the thermoplastic resin, and a dispersion step of dispersing the fibrous filler bundle into the thermoplastic resin.

[0010] [2] A method for producing a thermoplastic resin composition according to [1], characterized in that the dispersion step is performed after the distribution step.

[0011] [3] A method for producing a thermoplastic resin composition according to [1] or [2], using a twin-screw extruder having a pair of screws.

[0012] [4] The method for producing a thermoplastic resin composition according to [3], characterized in that, in the dispersion step, a screw suitable for dispersion and a reverse-feed screw are paired together, and one or more such pairs are arranged in a continuous manner.

[0013] [5] A method for producing a thermoplastic resin composition according to [3] or [4], characterized in that, in the dispersion step, a screw suitable for dispersion and a reverse-feed screw are paired and arranged in two or more sets in succession.

[0014] [6] The length of the screw combination in the dispersion process (L C L is the ratio of ( ) to the screw diameter (D). CA method for producing a thermoplastic resin composition according to any one of [3] to [5], wherein a value of / D is 1.0 to 8.0.

[0015] [7] The method for producing a thermoplastic resin composition according to any one of [3] to [6], wherein a mixture containing the thermoplastic resin and the fibrous filler bundle passes through a full flight screw between the distributing step and the dispersing step.

[0016] [8] The method for producing a thermoplastic resin composition according to any one of [1] to [7], wherein an average fiber diameter of single fibers in the fibrous filler bundle is 14 µm or less.

[0017] [9] The method for producing a thermoplastic resin composition according to any one of [1] to [8], wherein the fibrous filler bundle dispersed in the thermoplastic composition is melt-kneaded in an amount of 5 parts by mass or more and 100 parts by mass or less relative to 100 parts by mass of the thermoplastic resin.

[0018]

[10] The method for producing a thermoplastic resin composition according to any one of [3] to [7], wherein a barrel diameter of the extruder used for the melt-kneading is 48 mm or more.

[0019]

[11] The method for producing a thermoplastic resin composition according to any one of [1] to

[10] , wherein when the obtained thermoplastic resin composition is subjected to a tensile test in accordance with ISO 527 at a tensile speed of 5 mm / min, an average tensile strength and a standard deviation are obtained from 20 tests, and a coefficient of variation of tensile strength calculated by dividing the standard deviation by the average tensile strength is 0.02 or less. Advantageous Effects of Invention

[0020] According to the production method of the present invention, it is possible to provide a method for producing a thermoplastic resin composition that is excellent in fiber opening property of the fibrous filler and provides a thermoplastic resin composition having good stability of tensile strength. Mode for Carrying Out the Invention

[0021] The following describes in detail embodiments for carrying out the present invention (hereinafter referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0022] <Method for producing thermoplastic resin compositions> The method for producing the thermoplastic resin composition of this embodiment (hereinafter also simply referred to as "the method for producing this embodiment") is characterized by melting a thermoplastic resin, supplying a bundle of fibrous filler and performing melt-kneading, and then going through a distribution step (hereinafter sometimes simply referred to as "distribution step") in which the bundle of fibrous filler is distributed into the thermoplastic resin, and a dispersion step (hereinafter sometimes simply referred to as "dispersion step") in which the bundle of fibrous filler is dispersed into the thermoplastic resin. According to the above method for producing the thermoplastic resin composition, the fibrous filler exhibits excellent fiber-opening properties, and the resulting thermoplastic resin composition has good tensile strength stability.

[0023] The order of the distribution and dispersion processes does not matter, but it is preferable to perform the dispersion process after the distribution process. This order promotes the opening of the fibrous filler fibers more effectively.

[0024] [Melting and mixing] Known devices can be used as the apparatus for melt-kneading. For example, melt-kneaders such as single-screw or twin-screw extruders, Banbury mixers, and mixing rolls can be used. Among these, multi-screw extruders equipped with a devolatilization mechanism (venting) device and side feeder equipment are preferred, and twin-screw extruders are more preferred. That is, it is more preferable to use a twin-screw extruder having a pair of screws.

[0025] The extruder used for melt mixing (i.e., the extruder used in the thermoplastic resin manufacturing method of this embodiment) preferably has a barrel diameter of 48 mm or more. With the thermoplastic resin composition manufacturing method of this embodiment, even if a larger extruder is used, the fiber-opening of the fibrous filler is excellent, and the stability of the tensile strength of the resulting thermoplastic resin composition is good (the coefficient of variation of tensile strength is small).

[0026] When melt-mixing in an extruder, the mixing conditions such as the resin temperature, degree of reduced pressure, and average residence time during extrusion can be set as appropriate. The resin temperature during melt-mixing is preferably above the melting point of the thermoplastic resin and below 360°C, more preferably between 5°C and 350°C, even more preferably between 10°C and 340°C, particularly preferably between 15°C and 335°C, and most preferably between 20°C and 330°C. Setting the resin temperature during melt-mixing above the lower limit ensures sufficient melting of the thermoplastic resin and tends to reduce the load on the melt-mixer. Furthermore, setting the resin temperature during melt-mixing below the upper limit tends to further suppress the decomposition of the thermoplastic resin itself. The resin temperature can be measured, for example, by directly contacting a thermometer such as a thermocouple with the molten mixture coming out of the extruder's discharge port (spindle). The resin temperature can be adjusted by controlling the heater temperature of the extruder cylinder, or by appropriately adjusting the amount of shear heat generated by changing the extruder's rotation speed and discharge volume.

[0027] The average residence time during melt mixing is preferably 10 seconds to 120 seconds, more preferably 20 seconds to 100 seconds, even more preferably 25 seconds to 90 seconds, particularly preferably 30 seconds to 80 seconds, and most preferably 35 seconds to 70 seconds. By setting the average residence time during melt mixing above the lower limit, the melt-mixed product tends to be obtained more efficiently. Also, by setting the average residence time during melt mixing below the upper limit, the extrusion discharge speed (production speed) tends to increase to some extent. As a result, the productivity of the thermoplastic resin composition also tends to improve. Note that the average residence time refers to the residence time if it is constant in the melt-mixing apparatus, and the average of the shortest residence time and the longest residence time if the residence time is non-uniform. By adding a component (hereinafter abbreviated as "component X") that can be distinguished from the raw thermoplastic resin used in melt mixing, such as a coloring agent masterbatch or a resin of a different color from the raw thermoplastic resin used in melt mixing, to the melt mixing apparatus, and measuring the start and end times of discharge when component X is at its highest concentration, the average residence time can be measured by averaging the start and end times of discharge. The average residence time can be appropriately adjusted by the discharge rate (discharge speed) and rotation speed of the extruder.

[0028] (Distribution process) The method for producing the thermoplastic resin composition of this embodiment involves a distribution step in which fibrous filler bundles are distributed into the thermoplastic resin during melt kneading. The distribution process is a process that promotes the repositioning of fibrous filler bundles in the molten thermoplastic resin, thereby evenly distributing the fibrous filler bundles within the thermoplastic resin. In this process, some fibrous filler bundles are opened, but this is insufficient.

[0029] When using a twin-screw extruder, examples of screws suitable for the distribution process include kneading discs with a forward helix angle of 45 degrees and a neutral helix angle of 90 degrees, and a reverse helix angle of 45 degrees, and a combination of screws with a screw length L to screw diameter D ratio L / D of 0.8 to 1.5. Each screw preferably has a configuration of five connected discs.

[0030] (Dispersion process) The method for producing the thermoplastic resin composition of this embodiment involves a dispersion step in which fibrous filler bundles are dispersed in the thermoplastic resin during melt kneading. The dispersion process is a process in which unopened fibrous fillers in a thermoplastic resin composition are opened and uniformly distributed within the resin.

[0031] When using a twin-screw extruder, examples of screws suitable for the dispersion process include kneading discs with a forward helix angle of 45 degrees, a neutral helix angle of 90 degrees, and a reverse helix angle of 45 degrees, and a combination of screws with a screw length L to screw diameter D ratio (L / D) of 0.3 to 0.8. Each screw preferably has a configuration of five connected discs. Furthermore, as an example of a screw suitable for other dispersion processes, it is preferable to use a combination of a forward or reverse screw having a notch in the flight portion and a reverse screw. Examples of notch shapes include arc-shaped, U-shaped, V-shaped, and rectangular shapes.

[0032] In the dispersion process, it is preferable to arrange one or more sets of a screw suitable for the above dispersion and a reverse-feed screw, and it is more preferable to arrange two or more sets in succession.

[0033] In the dispersion process, the length of the screw combination (L C L is the ratio of ( ) to the screw diameter (D). C The value of / D is preferably 1.0 to 8.0, more preferably 1.1 to 7.0, particularly preferably 1.2 to 6.0, and most preferably 1.3 to 5.0. The length of the screw combination in the dispersion process (L C By setting the ratio of () to the screw diameter (D) within this range, the fibrous filler is sufficiently opened, and the generation of unopened fibrous filler is suppressed.

[0034] Furthermore, it is preferable to place one or more full-flight screws between the distribution step and the dispersion step. That is, it is preferable that the mixture containing the thermoplastic resin and the fibrous filler bundle passes through the full-flight screw between the distribution step and the dispersion step.

[0035] Next, the raw materials used in the method for producing the thermoplastic resin composition of this embodiment will be described in detail below.

[0036] (thermoplastic resin) Specifically, polyamide or polyester is preferred as the thermoplastic resin, with polyamide being more preferred.

[0037] Examples of polyamides include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polytetramethylene sevacamide (nylon 410), polypentamethylene adipamide (nylon 56), polypentamethylene sevacamide (nylon 510), polyhexamethylene sevacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polydecamethylene adipamide (nylon 106), polydecamethylene sevacamide (nylon 1010), and polydecamethylene. Methylene dodecamide (Nylon 1012), Polyundecaneamide (Nylon 11), Polydodecaneamide (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 / Polydodecaneamide copolymer (Nylon 6T / 12), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide / Polyhexamethylene isophthalamide copolymer (Nylon 66 / 6T / 6I), Polyxylylene adipamide (Nylon XD6), Polyxylylene sebaamide (Nylon XD10), 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).In this context, " / " indicates a copolymer. These polyamides may be used individually or in combination of two or more. Among these, polyamide 6, polyamide 66, or polyamide 610 are preferred, with polyamide 66 being particularly preferred. Polyamide 66 itself is a polyamide resin that is already generally known 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 lactams, aminocarboxylic acids, and combinations of other diamines and dicarboxylic acids, based on the total mass of all monomer units.

[0038] Furthermore, these polyamides may be commercially available or manufactured using known methods. Specific examples of methods for producing polyamides are not particularly limited, but include methods such as ring-opening polymerization of lactams, self-condensation of ω-aminocarboxylic acids, and condensation of diamines and dicarboxylic acids.

[0039] The above polyamide preferably has a viscosity number VN of 100 to 350, more preferably 100 to 330, and even more preferably 110 to 300. The viscosity number can be measured in accordance with ISO 307 (JIS-K6933).

[0040] 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 individually or in combination of two or more. Specific examples of polyesters include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate.

[0041] In the method for producing the thermoplastic resin composition of this embodiment, in addition to polyamide or polyester, other thermoplastic resins can be used as the raw material resin. Other thermoplastic resins include, for example, general-purpose resins such as polyethylene, polypropylene, ethylene-propylene copolymer, polystyrene, ABS resin, AS resin, and acrylic resin; polycarbonate, polyphenylene oxide, 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. Among these, resins without functional groups, such as polyethylene, polypropylene, or ethylene-propylene copolymer, are preferably modified before use.

[0042] (Fibrous filler) Examples of fibrous fillers include glass fibers, carbon fibers, wollastonite, and potassium titanate. Among these, glass fibers are preferred from the viewpoint of physical properties, safety, and economic efficiency. It is preferable to use glass fibers that are bound together with a known binder mainly composed of acrylic resin, epoxy resin, or urethane resin, and more preferably glass fibers bound together with a binder mainly composed of acrylic resin or epoxy resin. Furthermore, since further improvement in the mechanical properties of the resulting molded product can be expected, it is preferable to use glass fibers that have been pre-treated with a coupling agent such as an isocyanate compound, organosilane compound, organotitanate compound, organoborane compound, or epoxy compound. In this specification, bundled fibrous fillers may be referred to as "bundles of fibrous fillers."

[0043] The average fiber diameter of the single fibers in the fibrous filler bundle is preferably 14 μm or less, more preferably 2 to 12 μm, even more preferably 3 to 10 μm, and most preferably 4 to 8 μm. With the method for producing the thermoplastic resin composition of this embodiment, the effects of the present invention can be achieved even with fibrous fillers of a smaller diameter. The average fiber diameter can be determined by the method described in the examples.

[0044] In the method for producing the thermoplastic resin composition of this embodiment, it is preferable to melt-knead the fibrous filler bundle in an amount of 5 to 100 parts by mass per 100 parts by mass of thermoplastic resin, more preferably 6 to 50 parts by mass, and even more preferably 8 to 40 parts by mass. With the method for producing the thermoplastic resin composition of this embodiment, the effects of the present invention can be achieved even with a smaller amount of fibrous filler.

[0045] (copper compound) In the melt-mixing process, copper compounds can be further added in addition to the thermoplastic resin and fibrous filler. Examples of copper compounds include inorganic copper salts such as cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous 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. Among these, cuprous iodide is preferred. These copper compounds may be used individually or in combination of two or more.

[0046] The amount of copper compound blended is preferably 0.0001 parts by mass or more and 1 part by mass or less per 100 parts by mass of thermoplastic resin, more preferably 0.005 parts by mass or more and 0.2 parts by mass or less, and even more preferably 0.02 parts by mass or more and 0.1 parts by mass or less.

[0047] (Metal halides) In the melt-mixing process, metal halides can be added in addition to the thermoplastic resin and fibrous filler. However, in this invention, among the metal halides, those that also fall under the category of copper compounds, i.e., copper halides, are not included in the metal halides. In other words, in the melt-mixing process, metal halides (excluding copper halides) can be added in addition to the thermoplastic resin and fibrous filler. Potassium halides are preferred as metal halides. Examples of potassium halides include potassium iodide, potassium bromide, and potassium chloride. Among these, potassium iodide is preferred. These potassium halides may be used individually or in combination of two or more.

[0048] The amount of metal halide added 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 0.2 parts by mass or less, and even more preferably 0.02 parts by mass or more and 0.15 parts by mass or less, per 100 parts by mass of thermoplastic resin.

[0049] <Thermoplastic resin composition> The thermoplastic resin composition obtained by the manufacturing method of this embodiment preferably has a viscosity number VN of 100 to 350, more preferably 100 to 330, and even more preferably 110 to 300. When VN is above the lower limit, the abrasion resistance is better, while when VN is below the upper limit, the moldability is better when molded for each application. The viscosity number can be measured in accordance with ISO 307 (JIS-K6933).

[0050] The content of fibrous filler in a thermoplastic resin composition is preferably 5 parts by mass or more and 100 parts by mass or less per 100 parts by mass of thermoplastic resin. A fibrous filler content above the lower limit allows for greater rigidity and strength of the thermoplastic resin composition, while a content below the upper limit results in better moldability when the thermoplastic resin composition is molded for various applications.

[0051] The thermoplastic resin composition obtained by the above manufacturing method is subjected to a tensile test at a tensile speed of 5 mm / min in accordance with ISO 527, and the average tensile strength and standard deviation are determined over 20 tests. The coefficient of variation of the tensile strength, obtained by dividing the standard deviation by the average tensile strength, is preferably 0.02 or less, more preferably 0.018 or less, particularly preferably 0.016 or less, and most preferably 0.015 or less. A molded product exhibiting stable tensile strength can be obtained by having a coefficient of variation of tensile strength of 0.02 or less.

[0052] The average fiber length of the fibrous filler contained in the thermoplastic resin composition is preferably 100 μm or more and 1000 μm or less. When the average fiber length of the fibrous filler is above the lower limit, it can exert a more sufficient reinforcing effect and further improve impact strength and tensile strength. On the other hand, when the average fiber length is above the lower limit, it is possible to more effectively suppress the fibrous filler from flying out of the pellets and reducing the bulk density of the pellets when the thermoplastic resin composition is pelletized. The average fiber length of the fibrous filler can be measured by the method described in the examples.

[0053] The thermoplastic resin composition obtained by the manufacturing method of this embodiment has a reduced amount of unopened fibrous filler and stable physical properties, making it suitable for use in applications such as automobile parts, electronic and electrical components, industrial machinery parts, and various gears. [Examples]

[0054] The embodiment will be described in detail below with reference to specific examples and comparative examples, but this embodiment is not limited in any way to the following examples and comparative examples.

[0055] <Method for measuring resin properties> Various physical properties were measured using the methods described below. Furthermore, various evaluations were conducted using the methods described below.

[0056] (Spreadability) After weighing 10 kg of the thermoplastic resin composition pellets obtained in the examples and comparative examples, the thermoplastic resin composition pellets containing glass fiber bundles were visually sorted, and the number of pellets containing unopened glass fiber bundles was determined. The following criteria were used to evaluate the number of pellets containing unopened glass fiber bundles. A:0~10 pieces B: 11~20 pieces C: 21~30 pieces D:31~50 pieces E:51~200 pieces F: 201 or more

[0057] (Number average fiber length) The thermoplastic resin composition pellets obtained in the examples and comparative examples were heated in an electric furnace at 650°C for more than 2 hours to burn off the organic matter. The remaining fibers were then photographed using a microscope, the lengths of more than 500 fibers were measured, and the average of the measured fiber lengths was calculated to obtain the number-average fiber length.

[0058] (filler a / b) Let (a) be the number-average fiber length calculated using the method described above (number-average fiber length), and let (b) be the fiber diameter of the fiber used. Then, a / b was calculated by dividing (a) by (b).

[0059] (Average tensile strength and standard deviation) Using the thermoplastic resin composition pellets obtained in the examples and comparative examples, multi-purpose test specimens (Type A) were molded using an injection molding machine (PS-40E: manufactured by Nissei Plastic Co., Ltd.) in accordance with ISO 3167. During the molding process, the injection and holding pressure time was set to 25 seconds, the cooling time to 15 seconds, the mold temperature to 80°C, and the molten resin temperature to 280°C. Using the obtained multi-purpose test specimens (Type A), tensile tests were performed at a tensile speed of 5 mm / min in accordance with ISO 527. The tensile strength was measured for n=20 specimens, and the average tensile strength and standard deviation were determined.

[0060] (Coefficient of variation of tensile strength) The coefficient of variation was calculated from the average tensile strength and standard deviation obtained above, according to the following formula. Coefficient of variation = Standard deviation / Average tensile strength

[0061] (viscosity number VN) The viscosity number VN was measured using polyamide resin compositions in accordance with ISO 307 (JIS-K6933). Specifically, a solution with a polyamide resin composition concentration of 0.5% by mass was prepared using 96% by mass sulfuric acid at 25°C, and the viscosity was measured at 25°C. When the polyamide resin composition contained fibrous fillers such as glass fibers, the ash content in the polyamide resin composition was measured in advance, for example, according to the provisions of ISO 3451-4, and the polyamide resin content was calculated from the polyamide resin composition by using the polyamide resin content obtained by subtracting the ash content.

[0062] <Raw materials> The following ingredients were used. ((A) Thermoplastic resin) • Polyamide resin A1: Polyamide 66, manufactured by the method described in Manufacturing Example 1 below. • Polyamide resin A2: Polyamide 66, manufactured by the method described in Manufacturing Example 2 below.

[0063] ((B) Fibrous filler) • Fibrous filler B1: Chopped strands, manufactured using the method described in Manufacturing Example 3 below. • Fibrous filler B2: Chopped strands, manufactured by the method described in Manufacturing Example 4 below. • Fibrous filler B3: Chopped strands, manufactured by the method described in Manufacturing Example 5 below.

[0064] ((C) copper compound) • Copper iodide: Copper(I) iodide, manufactured by Wako Pure Chemical Industries, Ltd.

[0065] ((D) Metal halides) • Potassium iodide: Potassium iodide, manufactured by Wako Pure Chemical Industries, Ltd.

[0066] 1. (A) Manufacturing of thermoplastic resins [Manufacturing Example 1] (Production of polyamide resin A1: 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 component, were dissolved in 15,000 g of distilled water to obtain a 50% by mass aqueous solution of the raw material monomer. The obtained aqueous solution was placed in a 40 L autoclave, and the autoclave was purged with nitrogen. This aqueous solution was concentrated by gradually removing water vapor while stirring at a temperature between 110°C and 150°C until the solution concentration reached 70% by mass. Then, the internal temperature was 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 water vapor and maintaining the pressure at 1.8 MPa until the internal temperature reached 270°C. Then, the pressure was reduced to atmospheric pressure over approximately 1 hour. After reaching atmospheric pressure, the solution was discharged in strand form from the lower nozzle, water-cooled, and cut to obtain pellets of polyamide resin A1. The resulting pellets were dried in a nitrogen atmosphere at 90°C for 4 hours. The viscosity number VN of these pellets was 122, and the melting point was 265°C.

[0067] [Manufacturing Example 2] (Production of polyamide resin A2: polyamide 66) 10 kg of pellets obtained in [Manufacturing Example 1] were placed in a conical ribbon vacuum dryer (manufactured by Okawara Seisakusho Co., Ltd., product name Ribocone RM-10V), and nitrogen was flowed through at 10 L / min while stirring to perform nitrogen purging. The pellets were heated at a temperature of 215°C for 6 hours while stirring and continuing to flow nitrogen at 10 L / min. After that, the temperature was lowered while continuing to flow nitrogen, and the pellets were removed from the apparatus when the temperature reached approximately 50°C. The viscosity number VN of these pellets was 260, and the melting point was 262°C.

[0068] 2. (B) Manufacturing of fibrous fillers [Manufacturing Example 3] (Manufacturing of fibrous filler B1) First, (x-1) to (x-4), described below, were diluted with water to obtain a glass fiber scrubber, with solid components consisting of 2% by mass of polyurethane resin, 4% by mass of maleic anhydride-butadiene copolymer, 0.6% by mass of γ-aminopropyltriethoxysilane, and 0.1% by mass of carnauba wax. The obtained glass fiber sizing agent was applied to glass fibers with a number-average fiber diameter of 7 μm. The application method involved applying the sizing agent to the glass fibers using an applicator installed while the melt-proofed glass fibers were being wound onto a rotating drum. Subsequently, the glass fibers to which the sizing agent had been applied were dried to obtain rovings of glass fiber bundles surface-treated with the glass fiber sizing agent. At this time, the glass fibers were bundled in units of 1,000. The amount of glass fiber sizing agent applied to the glass fibers was 0.6% by mass. The obtained rovings were cut to a length of 3 mm to obtain fibrous filler B1 (chopped strands, hereinafter simply abbreviated as "(B1)"). The components (x-1) to (x-4) that make up the sizing agent used in the preparation of the fibrous filler are as follows: (x-1) Polyurethane resin emulsion Product name: Bondic (registered trademark) 1050 (manufactured by Dainippon Ink Co., Ltd.) (Aqueous solution with 50% solid content by mass) (x-2) Maleic anhydride-based copolymer emulsion Product Name: Acrobinder (Registered Trademark) BG-7 (Manufactured by Sanyo Chemical Industries, Ltd.) (Aqueous solution with 25% solid content by mass) (x-3) Aminosilane coupling agent Product name: KBE-903 (manufactured by Shin-Etsu Chemical Co., Ltd.) γ-aminopropyltriethoxysilane (x-4) Lubricant Product name: Carnauba wax (manufactured by Kato Yoko Co., Ltd.)

[0069] [Manufacturing Example 4] (Manufacturing of fibrous filler B2) Fibrous filler B2 (chopped strand, hereinafter simply abbreviated as "(B2)") was obtained using the same method as in Production Example 3 above, except that glass fibers with a number average fiber diameter of 5 μm were used instead of glass fibers with a number average fiber diameter of 7 μm. The amount of glass fiber scrubbing agent adhering to the glass fibers was 0.7% by mass.

[0070] [Manufacturing Example 5] (Manufacturing of fibrous filler B3) A fibrous filler (B3) (chopped strand, hereinafter simply abbreviated as "(B3)") was obtained in the same manner as in Production Example 3, except that glass fibers with a number-average fiber diameter of 13 μm were used instead of glass fibers with a number-average fiber diameter of 7 μm. The amount of glass fiber scrubbing agent adhering to the glass fibers was 0.4% by mass.

[0071] <Manufacturing of polyamide resin compositions> (Extruder) Extrusion was carried out using a TEM-58SX twin-screw extruder (manufactured by Shibaura Machine Co., Ltd.) according to the compound composition, screw configuration, and extrusion conditions described in Table 1. The extruder has a 13-barrel configuration, with a raw material supply port in the first barrel, a melting zone (combination of various kneading discs) located from the fourth to the fifth barrel as kneading 1, a side feed port in the sixth barrel, kneading 2 located from the seventh to the eighth barrel, kneading 3 located from the tenth to the eleventh barrel, and a vent port in the twelfth barrel.

[0072] (Screw configuration) The screw configurations used in the examples and comparative examples are as follows. Distribution 1: A configuration consisting of two sets of kneading discs arranged consecutively, with one set being a 45-degree angled 5-blade kneading disc (L / D=1) and the other a 90-degree angled 5-blade kneading disc (L / D=1). Distribution 2: A configuration in which three consecutive 45-degree angled, 5-blade kneading discs (L / D=1) are arranged. Distribution 1: A configuration consisting of two 45-degree five-blade kneading discs (L / D=0.5), one 90-degree five-blade kneading disc (L / D=0.5), one 45-degree five-blade kneading disc (L / D=0.5), one 90-degree five-blade kneading disc (L / D=0.5), and one reverse-feed 45-degree five-blade kneading disc (L / D=0.5). Distribution 2: A configuration consisting of two notched feed flight screws (L / D=0.75), one reverse feed flight screw (L / D=0.375), one notched feed flight screw (L / D=0.75), and one reverse feed flight screw (L / D=0.375). Distribution 3: A configuration consisting of two notched feed flight screws (L / D=0.75) and one reverse feed flight screw (L / D=0.375).

[0073] [Example 1] A mixture of polyamide resin A1 obtained in Production Example 1, impregnated with a copper compound and a halide, was blended according to the formulation composition shown in Table 1 and supplied as the top feed. Fibrous filler B1 obtained in Production Example 3 was supplied as the side feed. Using the extruder screw configuration shown in Table 1, the set temperature was 300°C up to the melting zone, 260°C thereafter, and the die head temperature was 300°C (in Table 1, the barrel temperature column is indicated as "temperature in the melting zone / temperature thereafter / temperature in the die head"), and melt kneading was performed under extrusion conditions of screw rotation speed 600 rpm and discharge rate 600 kg / h to obtain thermoplastic resin composition pellets (molten kneaded material). Various evaluation results are shown in Table 1.

[0074] [Examples 2 and 7] Except for changing the extruder screw configuration as shown in Table 1, melt kneading was carried out in the same manner as in Example 1 to obtain thermoplastic resin composition pellets (melt kneaded product). The results of various evaluations are shown in Table 1.

[0075] [Comparative Examples 1-4] Except for changing the extruder screw configuration as shown in Table 1, melt kneading was carried out in the same manner as in Example 1 to obtain thermoplastic resin composition pellets (melt kneaded product). The results of various evaluations are shown in Table 1.

[0076] [Examples 3-4] Except for changing the amount of fibrous filler as shown in Table 1, melt kneading was carried out in the same manner as in Example 1 to obtain thermoplastic resin composition pellets (melt kneaded product). The results of various evaluations are shown in Table 1.

[0077] [Comparative Examples 5-6] Except for changing the extruder screw configuration as shown in Table 1, melt kneading was carried out in the same manner as in Example 3 or Example 4 to obtain thermoplastic resin composition pellets (molten kneaded product). The results of various evaluations are shown in Table 1.

[0078] [Examples 5-6] Except for changing the fiber diameter of the fibrous reinforcing material as shown in Table 1, melt kneading was carried out in the same manner as in Example 1 to obtain thermoplastic resin composition pellets (melt kneaded product). The results of various evaluations are shown in Table 1.

[0079] [Example 8] Since high-viscosity polyamide resin A2 was used instead of polyamide resin A1, the set temperature was 320°C up to the melting zone, 300°C thereafter, and the die head temperature was 300°C. Extrusion was performed under extrusion conditions of screw rotation speed of 250 rpm and discharge rate of 200 kg / h to obtain thermoplastic resin composition pellets (molten mixture). Various evaluation results are shown in Table 1.

[0080] [Table 1]

[0081] A comparison of the examples and comparative examples shows that, according to the manufacturing method of the present invention, the amount of pellets containing unopened fibrous filler is reduced by including the distribution step and the decomposition step, resulting in a smaller coefficient of variation. Furthermore, Comparative Examples 5 and 6 showed a tendency for the number of pellets containing unopened fibrous filler to increase as the amount of glass fiber decreased. Furthermore, from Examples 5 and 6, it was observed that as the fiber diameter decreased, the number of pellets containing unopened fibrous filler tended to increase. In Example 8, when a high molecular weight polyamide resin was incorporated, the melt viscosity was high, and melt kneading could not be performed under the same conditions as the others. However, despite reducing the screw rotation speed, the kneading capacity was strong due to the high melt viscosity, and pellets containing unopened fibrous filler were not generated. In Comparative Examples 3 and 4, a large amount of pellets containing unopened fibrous filler were generated, resulting in unstable strands emerging from the spindle. [Industrial applicability]

[0082] The method for producing a thermoplastic resin composition containing fibrous filler according to this embodiment results in fewer unopened fibers in the fibrous filler and good stability of tensile strength, making it suitable for use in applications such as automobile parts, electronic and electrical components, industrial machinery parts, and various gears.

Claims

1. A method for producing a thermoplastic resin composition containing a fibrous filler, After melting the thermoplastic resin, a bundle of fibrous filler material is supplied and melt-kneaded. A method for producing a thermoplastic resin composition, characterized in that the melt kneading process includes a distribution step of distributing the fibrous filler bundle into the thermoplastic resin, and a dispersion step of dispersing the fibrous filler bundle into the thermoplastic resin.

2. A method for producing a thermoplastic resin composition according to claim 1, characterized in that the distribution step is followed by the dispersion step.

3. A method for producing a thermoplastic resin composition according to claim 1 or 2, using a twin-screw extruder having a pair of screws.

4. The method for producing a thermoplastic resin composition according to claim 3, characterized in that, in the dispersion step, a screw suitable for dispersion and a reverse-feed screw are paired together, and one or more such pairs are arranged in a continuous manner.

5. The method for producing a thermoplastic resin composition according to claim 3, characterized in that, in the dispersion step, a screw suitable for dispersion and a reverse-feed screw are paired together, and two or more such pairs are arranged in succession.

6. The length of the screw combination in the aforementioned dispersion process (L Ｃ L is the ratio of ( ) to the screw diameter (D). Ｃ A method for producing a thermoplastic resin composition according to claim 3, characterized in that the value of / D is 1.0 to 8.

0.

7. A method for producing a thermoplastic resin composition according to claim 3, characterized in that, between the distribution step and the dispersion step, the mixture containing the thermoplastic resin and the fibrous filler bundle passes through a full-flight screw.

8. A method for producing a thermoplastic resin composition according to claim 1 or claim 2, characterized in that the average fiber diameter of the single fibers in the fibrous filler bundle is 14 μm or less.

9. A method for producing a thermoplastic resin composition according to claim 1 or claim 2, characterized in that the fibrous filler bundle dispersed in the thermoplastic composition is melt-kneaded in an amount of 5 to 100 parts by mass per 100 parts by mass of the thermoplastic resin.

10. A method for producing a thermoplastic resin composition according to claim 3, characterized in that the extruder used for the melt kneading has a barrel diameter of 48 mm or more.

11. A method for producing a thermoplastic resin composition according to claim 1 or 2, characterized in that the obtained thermoplastic resin composition is subjected to a tensile test at a tensile speed of 5 mm / min in accordance with ISO 527, the average tensile strength and standard deviation are determined over 20 tests, and the coefficient of variation of the tensile strength obtained by dividing the standard deviation by the average tensile strength is 0.02 or less.

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