Method for producing thermoplastic resin composition

Abstract

A method for producing a thermoplastic resin composition, the method including a kneading step for melting and kneading a thermoplastic resin and bundles of fibrous filler inside a barrel using a twin screw extruder having a pair of screws inside the barrel, wherein the method for producing a thermoplastic resin composition includes a pre-kneading step for melting and kneading the thermoplastic resin and bundles of fibrous filler inside the barrel in advance before the kneading step, the pre-kneading step is implemented in a pre-kneading zone positioned on the upstream side of a kneading zone where the kneading step is implemented, kneading discs are installed on the pair of screws inside the pre-kneading zone, and the maximum value of the distance between the distal end of the kneading disc and the position on the inner wall of the barrel that opposes the distal end of the kneading disc is 1.00-4.00 mm.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a thermoplastic resin composition containing a fibrous filler. [Background technology]

[0002] Thermoplastic resins have excellent moldability, mechanical properties, weather resistance, and other properties, and are therefore widely used in a variety of applications, including injection molding, automotive parts, electrical and electronic parts, and the like. Generally, to further improve the properties of thermoplastic resins or to compensate for their shortcomings, various additives are added to thermoplastic resins to prepare resin compositions. For example, fibrous fillers such as glass fibers are added to improve mechanical strength.

[0003] When producing a thermoplastic resin composition containing a dispersed fibrous filler such as glass fiber, the thermoplastic resin and the fibrous filler are typically melt-kneaded in a twin-screw extruder. The fibrous filler is typically prepared by coating the fibers serving as the filler with a surface treatment agent, a sizing agent, etc., bundling them into a large number of strands, cutting them into lengths of several millimeters, and feeding the resulting bundles (also called chopped strands) into the twin-screw extruder. During melt-kneading, the fibrous filler bundles are defibrated, thereby enabling the fibrous filler to be dispersed in the thermoplastic resin (see Patent Document 1).

[0004] However, some of the fibrous filler bundles may remain undefibrated. Since undefibrated fibrous filler may cause adverse effects such as clogging of the nozzle during injection molding or reducing the strength of the molded product, it is desirable that the fibrous filler bundles be fully defibrated.

[0005] Therefore, various proposals have been made as techniques for sufficiently defibrating fibrous filler bundles, such as using a reinforced element in the kneading zone in a twin-screw extruder where the thermoplastic resin and the fibrous filler bundles are kneaded, adding an element that imparts shear force to the kneading zone, or changing Q / Ns, where Ns is the screw rotation speed and Q is the discharge rate of the thermoplastic resin composition (see Patent Documents 2 to 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-6931 [Patent Document 2] Patent No. 5632235 [Patent Document 3] Patent No. 5536704 [Patent Document 4] Patent No. 5536705 Summary of the Invention [Problem to be solved by the invention]

[0007] In all of Patent Documents 2 to 4, various measures are taken in the kneading zone of a twin-screw extruder where a thermoplastic resin and a bundle of fibrous filler are melt-kneaded to reduce the amount of undefibrated bundles of fibrous filler. That is, conventionally, techniques for sufficiently defibrating bundles of fibrous filler have been specialized for the kneading zone.

[0008] The present invention has been made in consideration of the above-mentioned conventional problems, and an object of the present invention is to provide a method for producing a thermoplastic resin composition that can sufficiently defibrate bundles of fibrous filler. [Means for solving the problem]

[0009] One aspect of the present invention that solves the above problem is as follows. (1) A method for producing a thermoplastic resin composition, comprising a kneading step of melt-kneading a thermoplastic resin and a bundle of fibrous filler in a barrel of a twin-screw extruder having a pair of screws in the barrel, a preliminary kneading step of melt-kneading the thermoplastic resin and the bundles of fibrous filler in advance in the barrel before the kneading step, The preliminary kneading step is carried out in a preliminary kneading zone located upstream of a kneading zone in which the kneading step is carried out, A kneading disc is attached to the pair of screws in the preliminary kneading zone, The method for producing a thermoplastic resin composition, wherein the maximum value of the distance between the tip of the kneading disc and the position on the inner wall of the barrel facing the tip of the kneading disc is 1.00 to 4.00 mm.

[0010] (2) The method for producing a thermoplastic resin composition according to (1) above, wherein the thermoplastic resin is a polyarylene sulfide resin or a polybutylene terephthalate resin.

[0011] (3) The method for producing a thermoplastic resin composition according to (1) or (2) above, wherein the kneading discs in the preliminary kneading zone are eccentric triple-bladed kneading discs.

[0012] (4) The method for producing a thermoplastic resin composition according to any one of (1) to (3) above, wherein the length of the pre-kneading zone is 0.5D to 5.0D. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a method for producing a thermoplastic resin composition that can sufficiently defibrate bundles of fibrous filler. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a conceptual diagram showing the configuration of a twin-screw extruder used in the method for producing a thermoplastic resin composition of this embodiment. [Figure 2]FIG. 2 is a partial cross-sectional view showing an example of the arrangement of kneading discs (two rows) in the barrel of the preliminary kneading zone. [Figure 3] FIG. 3 is a partial cross-sectional view showing an example of the arrangement of kneading discs (three eccentric discs) in the barrel of the preliminary kneading zone. DETAILED DESCRIPTION OF THE INVENTION

[0015] The method for producing a thermoplastic resin composition according to this embodiment includes a kneading step in which a thermoplastic resin and a bundle of fibrous filler are melt-kneaded in the barrel of a twin-screw extruder having a pair of screws in the barrel. The method further includes a pre-kneading step in which the thermoplastic resin and the bundle of fibrous filler are melt-kneaded in advance in the barrel prior to the kneading step. The pre-kneading step is carried out in a pre-kneading zone located upstream of the kneading zone in which the kneading step is carried out. Furthermore, kneading discs are attached to the pair of screws in the pre-kneading zone, and the maximum distance between the tips of the kneading discs and the opposing position on the inner wall of the barrel is 1.00 to 4.00 mm.

[0016] In the method for producing a thermoplastic resin composition according to this embodiment, a twin-screw extruder is used to melt-knead a thermoplastic resin and a bundle of fibrous filler. Examples of twin-screw extruders include those configured as shown in FIG. 1. The twin-screw extruder 10 shown in FIG. 1 includes a first feed port 14 having a hopper 12 for feeding the thermoplastic resin, a plasticization zone 16, a second feed port 18, a preliminary kneading zone 20, a kneading zone 22, and a die 24. Granular thermoplastic resin fed from the hopper 12 to the first feed port 14 is transported as a solid to the plasticization zone 16 where it is melted. There are no limitations on the element configuration of the plasticization zone 16, as long as it is expected that most of the thermoplastic resin will melt. For example, the plasticization zone can be formed by combining two sets of 1.0D (disc thickness 0.2D x 5, offset angle 45°) forward-feeding two-row kneading disc elements in which the distance between the tip of the kneading disc on one side and the inner wall of the barrel is 0.40 mm, and one set of 1.0D (disc thickness 0.2D x 5, offset angle 45°) reverse-feeding two-row kneading disc elements in which the distance between the tip of the kneading disc on one side and the inner wall of the barrel is 0.40 mm. The second feed port 18 has, for example, a side feeder screw, from which a bundle of fibrous filler, such as glass fiber bundles, can be fed into the twin-screw extruder 10 . The pre-kneading zone 20 is located upstream of the kneading zone 22 and is a zone in which a composition containing a thermoplastic resin and fibrous filler bundles is preliminarily melt-kneaded before being kneaded in the kneading zone 22. The pre-kneading is carried out to actively bring the molten or unmolten thermoplastic resin and the fibrous filler bundles into contact (wet) with each other and to disperse the fibrous filler bundles to a certain degree of uniformity before the melt-kneading of the molten resin and the fibrous filler bundles is carried out in the kneading zone 22. In other words, the pre-kneading zone 20 serves to disperse the fiber bundles of the fibrous filler in the molten thermoplastic resin and to facilitate defibration of the fiber bundles in the kneading zone 22 located downstream. The kneading zone 22 is located downstream of the pre-kneading zone 20 and is a zone in which a composition containing a thermoplastic resin and bundles of fibrous filler that have been pre-kneaded is melt-kneaded. In the kneading zone 22, the fiber bundles of the fibrous filler are defibrated and the fiber length is also controlled. At this time, the fiber bundles of the fibrous filler are easily defibrated in the kneading zone 22 because they are dispersed in the thermoplastic resin by melt-kneading in the pre-kneading zone 20 as described above.

[0017] In this embodiment, the kneading step is performed in a kneading zone in the barrel of the twin-screw extruder. The pre-kneading step is performed in a pre-kneading zone located upstream of the kneading zone in the barrel of the twin-screw extruder. The "upstream side" of the twin-screw extruder refers to the side where the thermoplastic resin is introduced.

[0018] In this embodiment, in the preliminary kneading zone 20 of a twin-screw extruder 10 having a pair of screws with kneading discs attached thereto within the barrel, the maximum value of the distance between the tip of the kneading disc and the position on the inner wall of the barrel facing the tip of the kneading disc is 1.00 to 4.00 mm. If the maximum value of this distance is less than 1.00 mm, the amount of the kneaded mixture of molten resin and fibrous filler bundles to which stress is applied is limited, making it impossible to ensure good dispersion throughout the kneaded mixture. On the other hand, if the maximum value of this distance exceeds 4.00 mm, although the amount of the kneaded mixture of molten resin and fibrous filler bundles to which stress is applied increases, the applied stress is reduced, resulting in insufficient defibration of the fibrous filler bundles. The maximum value of this distance is preferably 2.00 to 4.00 mm.

[0019] The kneading discs in the preliminary kneading zone 20 will be described with reference to FIG. 2. FIG. 2 shows the arrangement of kneading discs 34, 36 attached to a pair of screws (not shown) in a barrel 32. The barrel 32 has a shape in which two cylindrical bodies are partially overlapped, and a screw is disposed in each of the two cylindrical bodies. The pair of screws are rotated in the same direction or in opposite directions by a driving means within the barrel 32, and the axes of their rotation coincide with the center O of a circle when the cross section of the cylindrical body is viewed as a circle. The kneading discs 34, 36 all have the same shape and are asymmetric with respect to the rotation axis (the center when the inner wall 38, 40 of the barrel 32 is viewed as a circle, respectively). More specifically, in the case of the kneading disc 34 located on the left side of FIG. 2, the distance d1 between the upper tip and the position on the inner wall 38 of the barrel 32 facing the upper tip is 1.00 to 4.00 mm. On the other hand, the distance between the lower tip of the kneading disc 34 and the position on the inner wall of the barrel 32 where the lower tip faces the disc is shorter than the distance d1, for example, 0.50 mm or less. In this way, by separating the tip of the kneading disc 34 by the distance d1 from the inner wall 38 of the barrel 32, it is possible to apply stress uniformly or nearly uniformly to the entire bundle of fibrous filler. Conversely, the lower tip is in close proximity to the inner wall 38 of the barrel 32, and the rotation of the kneading disc 34 has the function of cleaning the inner wall 38 of the barrel 32. The kneading disc 36 on the right side of FIG. 2 is similar to the kneading disc 34 on the left side. Note that all of the tips of the kneading discs may be configured to be separated from the positions where they face the inner wall of the barrel.

[0020] Next, another form of kneading discs (eccentric three-loop kneading discs) in the pre-kneading zone 20 will be described. The form shown in Fig. 3 differs from the form shown in Fig. 2 in the shape of the kneading discs. Fig. 3 shows the arrangement of kneading discs 44, 46 attached to a pair of screws (not shown) in a barrel. The kneading discs 44, 46 have a roughly equilateral triangular shape with three-fold rotational symmetry, with the center of symmetry being point b. On the other hand, the rotation axis of the screw, i.e., the rotation center of the kneading discs 44, 46, is point a, which is different from the position of point b, the center of symmetry. In other words, the kneading discs 44, 46 are attached so as to rotate eccentrically with respect to the rotation axis of the screw. Therefore, in the case of the kneading disc 44, the distance d2 between the tip and the opposing position of each tip on the inner wall 48 of the barrel is constant regardless of the rotation of the screw. The maximum value of the distance d2 is 1.00 to 4.00 mm. As with the kneading disc 44 on the left side, the distance between the tip and the opposing position on the inner wall 50 of the barrel of the kneading disc 46 on the right side of Fig. 3 is also constant regardless of the rotation of the screw.

[0021] The configuration of the kneading discs in the preliminary kneading zone 20 has been described above with reference to Figures 2 and 3, but this embodiment is not limited to the configuration shown in Figures 2 and 3. That is, there is no particular limitation as long as the maximum value of the distance between the tip end of the kneading disc and the inner wall of the barrel in the preliminary kneading zone 20 can be secured to be 1.00 to 4.00 mm. Any of a normal kneading disc, a shoulder cut kneading disc, an eccentric kneading disc, etc. may be used.

[0022] The thickness of the kneading discs in the preliminary kneading zone 20 is preferably 0.1D to 0.5D, more preferably 0.15D to 0.4D. When the thickness is 0.1D to 0.5D, the strength and durability are sufficient, and sufficient stress can be applied to the passing thermoplastic resin. In this specification, D means the inner diameter of the barrel. For example, when the thickness of a kneading disc is expressed as 0.5D, this means that the thickness is 0.5 times the inner diameter of the barrel.

[0023] The length of the pre-kneading zone 20 is preferably 0.5D to 5.0D, more preferably 1.0D to 4.0D, and even more preferably 1.5D to 4.0D. When the length of the pre-kneading zone 20 is 0.5D to 5.0D, the bundles of fibrous filler can be sufficiently dispersed in the thermoplastic resin, and the screw length is not excessively long, making it easy to ensure other zones. Note that as long as the total zone length is 0.5D to 5.0D, the kneading zone may exist alone or in multiple divided zones.

[0024] The kneading discs in the preliminary kneading zone 20 may be any of forward kneading discs, reverse kneading discs and orthogonal kneading discs, but forward kneading discs are preferred in terms of residence time and heat generation.

[0025] Preferred specific examples of kneading discs in the preliminary kneading zone 20 are shown below, but discs other than those shown in the examples below may be used as long as the maximum value of the distance between the tip of the kneading disc and the inner wall of the barrel is within a predetermined range. Furthermore, the kneading discs below may be used alone or in combination of two or more. In the following, the distance between the tip of the kneading disc and the position on the inner wall of the barrel facing the tip of the kneading disc is referred to as the "distance between the tip and the inner wall of the barrel." (1) A length of 4.0D is achieved by using four sets of 1.0D (disk thickness 0.2D x 5 pieces, offset angle 45°) progressive double-row kneading disc elements, with the distance between the tip and the barrel inner wall being 2.00 mm on either side. (2) A set of 1.0D (disc thickness 0.2D x 5 pieces, offset angle 45°) progressive two-row kneading disc elements with a distance of 2.00 mm on either side between the tip and the barrel inner wall, resulting in a length of 1.0D. (3) A 3.0D length is achieved by using three sets of 1.0D (disk thickness 0.2D x 5 pieces, offset angle 45°) progressive eccentric triple element with the distance between the tip and the barrel inner wall being 0.90mm, 3.80mm, and 3.80mm on each side. (4) A set of 1.0D (disk thickness 0.2D x 5, offset angle 45°) progressive eccentric triple element with a distance between the tip and the barrel inner wall of 0.90mm, 3.80mm, and 3.80mm on each side, making the length 1.0D.

[0026] In this embodiment, from the viewpoint of improving the dispersibility of the fibrous filler bundles, when the screw rotation speed is Ns and the discharge rate of the thermoplastic resin composition is Q, the ratio Q / Ns is preferably 0.5 to 4.0, and more preferably 0.6 to 3.0. From the same viewpoint, the inner diameter of the barrel is preferably 40 to 85 mm.

[0027] On the other hand, the kneading zone 22 is not particularly limited as long as it has elements having commonly used kneading discs that are effective for defibrating bundles of fibrous filler. The kneading discs in the kneading zone 22 may be any of forward kneading discs, reverse kneading discs, and orthogonal kneading discs. Specific examples of elements in the kneading zone 22 include a double-thread kneading disc, an eccentric triple-thread kneading disc, and a reverse-feed screw element having a single-thread flight portion with a plurality of notches formed therein.

[0028] Each component used in the method for producing the thermoplastic resin composition of this embodiment will be described below.

[0029] [Thermoplastic resin] In this embodiment, general-purpose plastics or engineering plastics can be used as the thermoplastic resin. Examples of the thermoplastic resin include polyarylene sulfide resins (PAS) such as polyphenylene sulfide resin (PPS), polybutylene terephthalate resin (PBT), polyacetal resin (POM), liquid crystal polymer (LCP), polyethylene terephthalate resin (PET), polypropylene (PP), and polyamide resin (PA). In this embodiment, polyarylene sulfide resin and polybutylene terephthalate resin are particularly suitable.

[0030] [Fiber filler] Examples of fibrous fillers include glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, silicon carbide whiskers, silicon nitride whiskers, potassium titanate whiskers, wollastonite, etc. Among these, when glass fibers are used, the effect of the manufacturing method of this embodiment is remarkable.

[0031] [Other ingredients] In the present embodiment, if necessary, one or more of general additives for thermoplastic resins, such as lubricants, release agents, antistatic agents, surfactants, flame retardants, organic polymer materials, inorganic or organic powdery or plate-like fillers, etc., may be added. [Example]

[0032] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples.

[0033] [Examples 1 to 11, Comparative Examples 1 to 5] In each example and comparative example, 100 parts by mass of polyphenylene sulfide resin was fed into a twin-screw extruder (extruder A or B) shown in Tables 1 and 2 through the first feed port and 66.7 parts by mass of glass fiber (fibrous filler) through the second feed port. These were melt-kneaded under the extrusion conditions (conditions 1 to 4) shown in Table 1 to obtain resin pellets. The twin-screw extruder used had the configuration shown in FIG. 1 , and in each example and comparative example, the preliminary kneading zone 20 and the kneading zone 22 were configured as shown in Tables 1 and 2. However, the preliminary kneading zone 20 was not provided in Comparative Example 1, and the kneading zone 22 was not provided in Comparative Example 5. That is, in Comparative Examples 1 and 5, no kneading elements were provided at the positions of the preliminary kneading zone 20 and the kneading zone 22, but instead, feed elements were used. The details of the eccentric triple-row or double-row kneading disc (double-row KD) in the preliminary kneading zone 20 and the "a" or "b" in the kneading zone 22 are described below.

[0034] (Extruder) Extruder A: TEX44αII (cylinder diameter: 47 mm), manufactured by Japan Steel Works, Ltd. Extruder B: TEX65αII (cylinder diameter: 69 mm), manufactured by Japan Steel Works, Ltd.

[0035] (Extrusion conditions) (1) Condition 1 Cylinder temperature: 300℃ Discharge rate per unit time: 150 kg / hr Screw rotation speed: 220 rpm (2) Condition 2 Cylinder temperature: 300℃ Discharge rate per unit time: 230 kg / hr Screw rotation speed: 338 rpm (3) Condition 3 Cylinder temperature: 300℃ Discharge rate per unit time: 230 kg / hr Screw speed: 298 rpm (4) Condition 4 Cylinder temperature: 300℃ Discharge rate per unit time: 400 kg / hr Screw rotation speed: 187 rpm

[0036] (Pre-mixing zone) Eccentric triple-thread kneading disc One or more progressive eccentric triple-row elements of the following shape were used so that the length of the pre-kneading section was 3.0D. The maximum value of the distance between the tip of the eccentric triple-row kneading disc and the opposing position of the tip of the eccentric triple-row kneading disc on the inner wall of the barrel is called the "maximum clearance." The same applies to the double-row kneading disc. Three clearances between the tip and barrel: 0.90mm, maximum clearance in the table, maximum clearance in the table Element length: 1.0D (disc thickness 0.2D x 5 pieces, offset angle 45°) · Double-row kneading disc (double-row KD) One or more of the forward-feeding two-row kneading elements having the following shape were used so that the length of the pre-kneading section was 3.0D. Tip end and barrel clearance: Maximum clearance in the table for both Element thickness: 1.0D (0.2D x 5 pieces, offset angle 45°)

[0037] (Mixing zone) a: FK(1.0D)-CK(1.0D)-BK(1.0D) b: FK(1.0D)-BMS(2.0D) Note that FK, CK, and BK are screw elements consisting of five double-kneading discs with a thickness of 0.2D. FK has a forward feed offset angle of 45 degrees, CK has an offset angle of 90 degrees, and BK has a reverse feed offset angle of 45 degrees. BMS is a reverse feed screw element with a single flight portion formed with 13 arc-shaped notches. The numbers in parentheses for each element indicate the thickness.

[0038] The details of each component used are as follows:

[0039] (1) Polyarylene sulfide resin PPS resin: Fortron KPS manufactured by Kureha Corporation (melt viscosity: 130 Pa·s (shear rate: 1200 sec) -1 , 310℃) (Melt viscosity measurement of PPS resin) The melt viscosity of the PPS resin was measured as follows. A capillograph manufactured by Toyo Seiki Seisakusho Co., Ltd. was used, and a flat die with a diameter of 1 mm and a length of 20 mm was used as the capillary. The cylinder temperature was 310°C and the shear rate was 1200 sec. -1 The melt viscosity was measured at 100°C. (2) Glass fiber Chopped strands of glass fiber with a fiber diameter of 10.5 μm and a length of 3.0 mm

[0040] [Table 1]

[0041] [Table 2]

[0042] [evaluation] <Evaluation of the number of undisintegrated glass fibers> For the pellet-shaped resin compositions obtained in each Example and Comparative Example, the number of undefibrated glass fibers was counted under the following measurement conditions using the following X-ray CT device (ScanXmate-D090SS270, manufactured by Comscan Techno Co., Ltd.). Specifically, 9 g of each resin pellet was placed in a sample cell, an X-ray CT transmission image was taken, and the number of undefibrated glass fiber bundles that appeared with high brightness was counted. The counting results are shown in Tables 1 and 2. (Measurement conditions) Tube voltage: 52kV Tube current: 154μA Resolution: 26μm / pixel

[0043] It can be seen from Tables 1 and 2 that in Examples 1 to 9, the number of undefibrated glass fiber bundles was 0 or 3, and the glass fiber bundles were well defibrated. On the other hand, Comparative Example 1, which differs from Examples 1 to 5 only in that it did not have a preliminary kneading zone, had an excessive number of undefibrated glass fiber bundles, and defibration was insufficient. Also, Comparative Examples 2 and 3, in which the maximum clearance was too small, and Comparative Example 4, in which the maximum clearance was too large, both had an excessive number of undefibrated glass fiber bundles, and defibration was insufficient. Furthermore, Comparative Example 5, in which a kneading zone was not provided, naturally had an excessive number of undefibrated glass fiber bundles, and defibration was insufficient.

[0044] [Examples 12 to 18, Comparative Examples 6 to 9] In each of the Examples and Comparative Examples, resin pellets were obtained in the same manner as in Example 1, except that the PPS resin was changed to the polybutylene terephthalate resin shown below, 43 parts by mass of glass fiber (fibrous filler) was added per 100 parts by mass of polybutylene terephthalate resin, and the extrusion conditions, pre-kneading element, maximum clearance, length of the pre-kneading zone, and kneading element were as shown in Tables 3 and 4. Furthermore, using the obtained resin pellets, the number of undefibrated glass fibers was evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4. (3) Polybutylene terephthalate resin PBT resin: PBT resin manufactured by Polyplastics Co., Ltd. (intrinsic viscosity (measured in o-chlorophenol at 35°C): 0.8 dL / g)

[0045] [Table 3]

[0046] [Table 4]

[0047] From Tables 3 and 4, it can be seen that in Examples 12 to 18, the number of undefibrated glass fiber bundles was 0 to 8, and the glass fiber bundles were well defibrated. On the other hand, Comparative Example 6, which differs from Examples 12 to 16 only in that it did not have a preliminary kneading zone, had an excessive number of undefibrated glass fiber bundles, and defibration was insufficient. Also, Comparative Example 7, in which the maximum clearance was too small, and Comparative Example 8, in which the maximum clearance was too large, both had an excessive number of undefibrated glass fiber bundles, and defibration was insufficient. Furthermore, Comparative Example 9, in which a kneading zone was not provided, naturally had an excessive number of undefibrated glass fiber bundles, and defibration was insufficient. [Explanation of symbols]

[0048] 10 Twin-screw extruder 12 Hopper 14 1st supply port 16 Plasticization Zone 18 2nd supply port 20 Pre-mixing zone 22 Mixing Zone 24 Die section 32 barrels 34 36 44 46 Kneading disc 38 40 50 Interior wall

Claims

1. A method for producing a thermoplastic resin composition, comprising a kneading step of melt-kneading a thermoplastic resin and a bundle of fibrous filler in a barrel of a twin-screw extruder having a pair of screws in the barrel, a preliminary kneading step of melt-kneading the thermoplastic resin and the bundles of fibrous filler in advance in the barrel before the kneading step, The preliminary kneading step is carried out in a preliminary kneading zone located upstream of a kneading zone in which the kneading step is carried out, A kneading disc is attached to the pair of screws in the preliminary kneading zone, a maximum value of the distance between the tip of the kneading disc and a position on the inner wall of the barrel facing the tip of the kneading disc is 1.00 to 4.00 mm.

2. The method for producing a thermoplastic resin composition according to claim 1, wherein the thermoplastic resin is a polyarylene sulfide resin or a polybutylene terephthalate resin.

3. The method for producing a thermoplastic resin composition according to claim 1 or 2, wherein the kneading discs in the preliminary kneading zone are eccentric triple-bladed kneading discs.

4. The method for producing a thermoplastic resin composition according to claim 1 or 2, wherein the length of the preliminary kneading zone is 0.5D to 5.0D.

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