JP2007290384A - Melt kneading device and production process of thermoplastic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a melt kneading device which inhibits a thermoplastic resin composition from adhering to a vent opening and a metalware bottom, also inhibits vent-up, continuously removes volatile matters, and achieves low-void thermoplastic resin pellets since cracked gas and volatile components generated in an extruder are pulled out of the thermoplastic resin. <P>SOLUTION: The melt kneading device of thermoplastic resin composition is composed of: a feeding section A; a melt kneading section B; a volatile matter removing section C; and a discharge section, wherein the volatile matter removing section C is equipped with a heating unit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a thermoplastic resin composition melt-kneading apparatus (hereinafter referred to as an extruder) and a method for producing a thermoplastic resin composition, and in particular, an external jacket heater having a volatile component removing section (hereinafter referred to as a vent section). Extruder capable of preventing vent-up that closes the flow path of volatile components by heating with a temperature etc. and obtaining thermoplastic resin pellets having excellent moldability and few voids, and this extruder The present invention relates to a method for producing a thermoplastic resin composition.

In the extruder, the raw material is plasticized by rotating a screw in a barrel, and extruded while kneading reinforcing fibers and granular fillers. In order to remove volatile substances and moisture contained in the melted raw material inside the extruder under vacuum (hereinafter referred to as degassing), the inside and outside of the barrel are located downstream of the kneading part of the extruder. Are connected to a metal plate (hereinafter referred to as a bent metal) having an opening for communicating with a cylindrical metal (hereinafter referred to as a vent port). In addition, a vacuum device is connected to the vent port, and volatile substances and moisture generated from the inside of the extruder are forcibly discharged from the side of the vent port. However, as the operation of the extruder (melting and kneading of the thermoplastic resin composition) continues, the molten resin may gradually adhere to the opening of the vent and harden, which may block the opening. Eventually, the pressure difference between the inside and the outside of the barrel causes a so-called vent-up in which the plasticized resin adhering to the vent opening is pushed up. When vent-up occurs, degassing is no longer performed, and a large amount of voids enter the thermoplastic resin pellets produced by the extruder in such a state. May occur, internal voids may be formed, and the molding cycle may be slow due to the time required for measurement during molding. Further, when the vent-up is severe, the resin composition being kneaded cannot be degassed, so that the strands are frequently blown out, making it difficult to manufacture the pellets themselves. In such a state, the operation of the extruder must be interrupted for maintenance, and the production efficiency is significantly hindered. Therefore, a device for preventing vent-up has been devised, and Patent Document 1 describes a melt-kneading apparatus for heating the bottom of the vent. Further, Patent Document 2 describes an apparatus that prevents an agglomerate of volatile matter from flowing again into the extruder by providing an inclined lid and a horizontal groove in the vent portion.
JP-A-8-244097 JP-A-18-26998

  However, in the method of heating the bottom of the vent described in Patent Document 1, vent-up prevention is insufficient, and particularly when a thermoplastic resin composition containing a large amount of reinforcing fibers and granular fillers is melt-kneaded, Since there are few plastic resin components, peeling of the resin composition from the screw frequently occurs, and vent-up cannot be completely suppressed. For this reason, there is a problem that voids increase in the obtained thermoplastic resin pellet. Moreover, in patent document 2, since the groove | channel inside a vent is horizontal, when melt-kneading what has a large volatile content, it overflows, and the aggregate of a volatile content will flow in into an extruder again.

  When the present invention melts and kneads reinforcing fibers and / or granular fillers with a thermoplastic resin using an extruder, the generated volatile matter is discharged to the outside without interruption, and voids inside the produced thermoplastic resin pellets are discharged. An object of the present invention is to provide a thermoplastic resin pellet that is reduced and has excellent moldability.

  Means for achieving the above object has the following configuration.

That is, the present invention
(1) A thermoplastic resin composition melt-kneading apparatus comprising a raw material supply unit (A), a melt-kneading unit (B), a volatile component removing unit (C), and a discharge unit, and heated to the volatile component removing unit (C) Thermoplastic composition melt-kneading apparatus provided with the apparatus,
(2) The thermoplastic resin melt-kneading apparatus according to (1), wherein the heating device is a jacket heater,
(3) The thermoplastic resin composition melt-kneading apparatus according to (1) or (2), comprising a plurality of raw material supply sections (A),
(4) The thermoplastic resin melt-kneading apparatus according to any one of claims 1 to 3, comprising a conical lid in the volatile component removing section (C),
(5) The thermoplastic resin melt-kneading apparatus according to any one of claims 1 to 4, wherein the volatile component removing section (C) includes a horizontal pipe for exhaust.
(6) The thermoplastic resin melt-kneading apparatus according to claim 5, comprising a groove with an inclination so as to descend toward the exhaust pipe on the inner wall of the volatile component removing part (C),
(7) A method for producing a thermoplastic resin composition that is melt kneaded using the thermoplastic resin composition melt kneader according to any one of (1) to (6),
(8) The method for producing a thermoplastic resin composition according to (7), wherein the volatile matter removing unit (C) is maintained at 230 to 330 ° C.
(9) The method for producing a thermoplastic resin composition according to (7) or (8), wherein the thermoplastic resin composition contains reinforcing fibers and / or granular fillers,
(10) The method for producing a thermoplastic resin composition according to (9), comprising 40 to 70 parts by weight of reinforcing fibers and / or granular fillers with respect to 100 parts by weight of the thermoplastic resin composition.

  In the present invention, the viscosity of the thermoplastic resin composition that comes into contact with the vent is reduced under the heated internal temperature of the vent port, so that the thermoplastic resin composition is prevented from sticking to the vent opening and the bottom of the bent hardware. Can do. As a result, vent-up can be prevented, and volatile components can be removed without interruption, and the cracked gas and volatile components generated in the extruder escape from the thermoplastic resin, so that thermoplastic resin pellets with less voids can be obtained. In addition, it is possible to prevent the occurrence of abnormal color tone pellets caused by the volatile agglomerates adhering to the vent portion and having deteriorated or discolored to flow again into the extruder. Furthermore, troubles in the extruder can be reduced, so that continuous productivity is greatly improved. Moreover, when it shape | molds using the pellet manufactured using the extruder of this invention, the molded article which does not have an internal void can be obtained.

  Next, embodiments of the present invention will be described with reference to the drawings.

  The extruder of the present invention is a thermoplastic resin composition melt-kneading apparatus comprising a raw material supply unit (A), a melt-kneading unit (B), a volatile component removing unit (C), and a discharge unit, C) is a thermoplastic composition melt-kneading apparatus provided with a heating apparatus. FIG. 1 shows an example of an extruder having a vent apparatus according to the present invention, which is in a state of being mounted on an extruder vent portion.

  As shown in FIG. 1, the extruder used in the present invention is an extruder having a screw 3 in a barrel 2. The basic configuration of the extruder is the same as that of the conventional extruder. In addition, although the twin-screw type extruder is used in FIG. 1, of course, it is not restricted to this, You may use a uniaxial type and a multi-axial type.

  A vent device 4 is mounted in the middle of the barrel 2 of the extruder. The vent device 4 used in the present invention is basically composed of a vent metal 5 having an opening 5a that communicates the inside and outside of the barrel 2 and a vent port 6 having a cylindrical exhaust pipe. An enlarged view of the vent portion of the example shown in FIG. 1 is shown in FIG. In addition, a vacuum device (not shown) is connected to the vent port 6 at the time of melt-kneading as in the prior art. A feature of the vent device 4 of the present invention is that a heating device 7 is provided on the outer surface of the vent port 6 that forms the basic structure of the vent device 4. The heating device 7 can be anything such as a ribbon heater, a metal band heater, a heating cable and an embedded cartridge heater that can heat the outer surface of the vent port. A jacket heater with a temperature preventing device is preferable (hereinafter, the heating device 7 is referred to as a jacket heater 7).

  The jacket heater 7 is preferably installed on the entire outer surface of the vent port 6 so as to efficiently heat the inside (portion 6a in the figure) and the inner wall surface of the vent port 6. By carrying out like this, the vent port inside 6a can be heated efficiently. However, when extruding a material having a large amount of volatile matter, the volatile matter agglomerated on the vent inner wall 6b in FIG. 2 is transmitted and flows into the extruder again, which may cause abnormal color tone pellets. . The inventions improved to prevent this are shown in FIGS. FIG. 3 is an extruder used in the present invention as in FIG. 1, and is an extruder having a screw 13 in a barrel 12. About the structure of an extruder, it is the same as that of the conventional extruder. In FIG. 3, a twin-screw type extruder is used. However, the present invention is not limited to this, and a single-screw type or a multi-screw type may be used. A vent device 14 is mounted in the middle of the barrel 12 of the extruder. The vent device 14 used in the present invention is basically composed of a vent hardware 15 having an opening 15a that communicates the inside and the outside of the barrel 12 and a vent port 16 having a cylindrical exhaust pipe. An enlarged view of the vent portion shown in FIG. 3 is shown in FIG. Further, as described above, a vacuum device (not shown) is connected to the vent port 16 at the time of melt-kneading as in the prior art. The vent device 14 according to the present invention is characterized in that (1) the heating device 17 is provided on the outer surface of the vent port 6 that forms the basic structure of the vent device 14, and (2) the top cover of the vent port is provided. It has a conical structure and its opening angle α is 90 to 160 °. (3) The angle β is inclined in the range of 10 to 45 ° so as to descend toward the exhaust port on the inner wall of the vent port. A groove.

  In the production method for producing a thermoplastic resin composition using the present invention, the raw material supplied from the raw material supply unit 1 (10) into the barrel 2 (12) is heated by the barrel 2 (12) and the screw 3 (13 ) Is carried while being melt-kneaded in front of the barrel 2 (12). At this time, it is preferable to supply the granular filler and / or reinforcing fiber from the raw material supply sections 1a (11a) and 1b (11b) in the middle of the barrel 2 (12) into the molten thermoplastic resin. By doing so, each raw material is uniformly melt-kneaded between the inner and downstream sides of the barrel 2 (12) to form a thermoplastic resin composition. When this thermoplastic resin composition reaches the opening 5a (15a) of the vent device 4 (14), the pressure is released here, and the decomposition gas, volatile components, etc. contained in the thermoplastic resin composition are separated. And discharged from the opening 5a (15a).

  At this time, in the conventional extruder, when the thermoplastic resin composition carried by the rotation of the screw 3 (13) enters the opening 5a (15a) in the barrel 2 (12), between the screws 8 (18). And the resin peeled from between the screw and the barrel wall 9 (19) scatters and adheres to the bent metal bottom 5c (15c). Further, in the vent device 4 (14), the volatile matter is removed by suction of the vacuum pump, so only the inside of the vent device is partially cooled. Therefore, the thermoplastic resin composition adhering to the bent metal bottom 5c (15c) is cooled and solidified and deposited on the bent metal bottom 5c (15c). The deposited resin grows further, and the resin that has lost its escape is clogged at the opening 5a, resulting in vent-up. Further, the cooled and solidified pieces of the thermoplastic resin composition may fall and be transported to the die of the extruder in an unmelted state, clog the holes of the die, and the strands may not be drawn.

  However, in the present invention, the thermoplastic resin composition is heated between the screws 8 (18) and between the screw and the barrel wall by heating the inner wall surface and bottom of the bent metal piece 5 (15) from the outer surface by the jacket heater 7 (17). Since it sticks to the screw without peeling from the space 9 (19), the cause of the occurrence of vent-up can be reduced, and the deaeration ability is improved. Even if the resin piece generated between the screws 8 (18) adheres to the bent metal bottom 5c, the jacket heater 7 (17) is installed and the high temperature can be maintained, so the viscosity of the thermoplastic resin composition is lowered. However, it does not lead to blockage. Further, even if the thermoplastic resin composition falls due to the decrease in the viscosity, since the thermoplastic resin composition itself is softened, the die is not clogged.

  In particular, in the improved apparatus of the present invention shown in FIGS. 3 and 4, in addition to the above-described effects, the top plate of the vent port is cooled by the amount of improved degassing capacity, and the volatile matter that aggregates increases. Due to the inclination and the effect of the groove with the inclination provided on the inner wall of the vent port, it is discharged out of the system by suction by a vacuum pump (not shown). The generation of colored pellets caused by mixing with the kneaded thermoplastic resin is eliminated.

  The extruder of the present invention and the method for producing a thermoplastic resin composition are suitable when melt kneading nylon, polybutylene terephthalate (hereinafter referred to as PBT), polyphenylene sulfide (hereinafter referred to as PPS), etc. as the thermoplastic resin. Can be used. For example, in the case of nylon, the temperature inside the vent is 225 ± 20 ° C., in the case of PBT, the temperature is 230 ± 20 ° C., and in the case of PPS, the bent metal upper surface 5c temperature is preferably 230 to 330 ° C., more preferably 250 to It is preferable to control to maintain 330 ° C, particularly preferably 270 to 330 ° C.

  Moreover, the manufacturing method of the thermoplastic resin composition of this invention is suitable for manufacture of the thermoplastic resin composition containing a reinforced fiber and / or a granular filler. In particular, it can be preferably carried out when producing a composition containing 40 to 70 parts by weight of reinforcing fibers and / or particulate fillers with respect to 100 parts by weight of the thermoplastic resin composition. Here, as the reinforcing fiber, those conventionally used as the reinforcing fiber of the thermoplastic resin composition can be used. Glass fiber, carbon fiber, asbestos fiber, carbon fiber, graphite fiber, metal fiber, potassium titanate whisker, boron Aluminum Whisker, Magnesium Whisker, Silicon Whisker, Slag Fiber, Gypsum Fiber, Silica Fiber, Silica / Alumina Fiber, Zirconia Fiber, Boron Nitride Fiber, Silicon Nitride Fiber and Boron Fiber, etc. Inorganic Reinforced Fiber, Polyester Fiber, Nylon Fiber Organic fiber such as acrylic fiber, regenerated cellulose fiber, acetate fiber, kenaf, ramie, cotton, jute, hemp, sisal, flax, linen, silk, manila hemp, sugar cane, wood pulp, paper waste, waste paper and wool . In addition, as the particulate filler, those conventionally used as the particulate filler of the thermoplastic resin composition can be used, and silicate minerals, silicate minerals and various minerals are pulverized into a plate shape or needle shape. And granular materials are preferably used. Specific examples include bentonite, dolomite, montmorillonite, barlite, finely divided silicic acid, aluminum silicate, silicon oxide, dosonite, shirasu balloon, clay, sericite, feldspar powder, talc, calcium carbonate, lithium carbonate, kaolin, zeolite ( (Including synthetic zeolite), talc, mica, synthetic mica and wollastonite (including synthetic wollastonite), glass flakes, glass beads, hydrotalcite and silica.

  In this example, a ZSK-90 R240P extruder manufactured by Werner was used, and a commercially available jacket heater 7 (manufactured by YAGAMI: model GYG) was installed at the vent portion, and filler components 40 to 70 such as glass fiber and calcium carbonate were used. The temperature of the bent metal upper surface 5c was measured in a state where the thermoplastic resin composition containing parts by weight was melted and kneaded, and the optimum temperature range in which the deaeration ability was improved without venting up was examined.

  As an example of the results using PPS, the vacuum pump was stopped when the temperature of the extruder was stabilized by melting and kneading, the upper lid of the vent device was opened, and immediately after opening the upper part of the bent metal using a surface thermometer. The surface temperature of 5c was measured. As a result, the complete blockage due to the vent-up was confirmed at the opening 5a in the range of 180 to 230 ° C. as measured values. However, as the temperature increased, the area of the opening 5a to which the resin adhered became smaller. In the range of actually measured values of 230 to 330 ° C., resin pieces adhering to the vicinity of the opening 5a can be seen, but even after 30 hours of continuous production without reaching a complete blockage, a high deaeration capability is achieved. Could be maintained. At the actually measured temperature of 270 to 330 ° C., the thermoplastic resin composition hardly adheres to the opening 5a and the vent-up does not occur for 48 hours or more, and the thermoplastic resin pellets having almost no voids can be continuously produced. It was.

  As in this embodiment, if the jacket heater 7 is installed on the outer surface of the bent metal 5 and the temperature at the bottom of the metal is maintained at 230 to 330 ° C., venting up due to the generation of scattered polymer and further clogging of the base will occur. It can suppress and can produce a thermoplastic resin pellet with few voids. Further, in the range of 270 to 330 ° C., it was possible to further maintain the deaeration ability. Similarly, the results obtained with other thermoplastic resins are shown in Table 1 below.

  FIG. 5 shows a schematic view of an apparatus for injection molding the thermoplastic resin pellets produced in the above-described embodiment.

  The injection molding mechanism feeds the raw material into the raw material hopper 20 and transports the resin while plasticizing in the direction of the nozzle 23 by the rotation of the screw 21 and the heat of the barrel 22. At this time, the bubbles in the thermoplastic resin pellet are compressed, driven toward the tip of the nozzle 23, and discharged to the outside together with the resin. After the mold clamping, the nozzle 23 is brought into close contact with the mold 24, and the plasticized thermoplastic resin composition 26 (molded product) filled in the tip of the nozzle by the hydraulic piston 25 is injected into the mold 24 and injected into the mold 24. Will be charged.

  Even after the mold 24 is filled, the resin shrinks due to the cooling of the resin, so that the injection pressure remains applied to maintain the filling rate in the mold. The filled state is maintained at a low pressure, and the mold 24 is cooled and solidified to a temperature that does not hinder removal.

  With the end of plasticization, the mold 24 begins to open, the injection device moves backward, and the nozzle 23 that has touched the mold 24 is separated from the mold 24. The molded piece is separated from the mold by operating the molded product ejecting device 17.

  In this example, when the jacket heater is used and when it is not used, the respective thermoplastic resin pellets are used, and the quality of the molded product when the molded product is manufactured by the injection molding process is compared. The result performed with the various thing shown in Table 1 as a thermoplastic resin is shown.

The thermoplastic resin pellets prepared without installing a jacket heater had a large volume of fine voids due to a decrease in the internal degassing capacity, so that the bulk density of the thermoplastic resin pellets was 0 with 40% filler-containing thermoplastic resin pellets. was 0.724 g / cm ³ in .648g ^/ cm 3, 70% content of the pellets.

  The pellets were polished to confirm the presence of voids therein, but a large amount of voids were present. The bulk density was measured based on JIS standard K6721.

  Further, although molding was attempted using the pellets, it could not be completely deaerated inside the molding machine and remained as a void inside the molded piece. If voids remain as voids in the molded product, the strength of the molded product is reduced, leading to troubles at customers.

On the other hand, the thermoplastic resin pellet prepared by winding the jacket heater around the outer surface of the vent port and maintaining the temperature of the bent metal at 270 to 330 ° C. has very few voids inside the pellet as a result of cross-sectional observation. The bulk density was 0.742 and 0.833 g / cm ³ , respectively, and the bulk density was high. Even when the pellets were molded, there were almost no voids inside the molded piece.

The thermoplastic resin composition used in this experiment is as follows.
Toray PPS A305MX01B (45% glass fiber, 5% calcium carbonate)
A310M (35% glass fiber, 35% calcium carbonate)
Toray PBT 1101GX65B (40% glass fiber)
Toray nylon CM1011G45 (40% glass fiber)

It is a cross-sectional view of an example of the extruder of the present invention. It is an expanded sectional view of the extruder vent part of FIG. It is a cross-sectional view of an extruder having a vent structure with a vent lid having a conical shape and an inclined groove. FIG. 4 is a cross-sectional view of a vent portion having a conical vent lid and an inclined groove. It is a cross-sectional view of the injection molding machine which shape | molds the pellet thermoplastic resin pellet created by this invention.

Explanation of symbols

A Raw material supply department
B Melting and kneading section
C Volatile removing unit 1 Main raw material supply hopper 1a Granular filler supply unit 1b Glass reinforcing fiber supply unit 2 Barrel 3 Screw 4 Vent 5 Vent metal 5a Vent opening 5b Vent metal surface 5c Vent metal bottom 6 Vent port 6a Vent port inside 7 Jacket heater 8 Screw engagement portion 9 Screw-barrel wall gap 10 Main raw material supply hopper 11a Granular filler supply portion 11b Glass reinforcing fiber supply portion 12 Barrel 13 Screw 14 Vent 15 Vent metal 15a Vent opening 15b Vent metal surface 15c Vent metal bottom 16 Vent port 16a Vent port interior 17 Jacket heater 18 Screw engagement portion 19 Screw-barrel wall gap α Open angle of conical top cover β Angle of inclined groove for collecting volatile agglomerates 20 Per 21 injection molding machine screw 22 molding machine barrel 23 molding machine injection nozzle 24 mold 25 hydraulic pump 26 moldings 27 molded article ejector

Claims (10)

A thermoplastic resin composition melt-kneading apparatus comprising a raw material supply part (A), a melt-kneading part (B), a volatile matter removing part (C), and a discharge part, wherein the volatile matter removing part (C) has a heating device. Thermoplastic composition melt kneading apparatus. The thermoplastic resin melt-kneading apparatus according to claim 1, wherein the heating apparatus is a jacket type heater. The thermoplastic resin composition melt-kneading apparatus according to claim 1 or 2, comprising a plurality of raw material supply sections (A). The thermoplastic resin melt-kneading apparatus according to any one of claims 1 to 3, wherein the volatile component removing section (C) includes a conical lid. The thermoplastic resin melt-kneading apparatus according to any one of claims 1 to 4, wherein the volatile component removing section (C) includes a horizontal pipe for exhaust. The thermoplastic resin melt-kneading apparatus according to claim 5, wherein the volatile matter removing portion (C) has an inner wall provided with an inclined groove so as to descend toward the exhaust pipe. The manufacturing method of the thermoplastic resin composition melt-kneaded using the thermoplastic resin composition melt-kneading apparatus in any one of Claims 1-6. The method for producing a thermoplastic resin composition according to claim 7, wherein the volatile component removing part (C) is maintained at 230 to 330 ° C. The manufacturing method of the thermoplastic resin composition of Claim 7 or 8 in which a thermoplastic resin composition contains a reinforced fiber and / or a granular filler. The method for producing a thermoplastic resin composition according to claim 9, comprising 40 to 70 parts by weight of reinforcing fibers and / or granular fillers with respect to 100 parts by weight of the thermoplastic resin composition.

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