JP2008036942A - Manufacturing process of thermoplastic resin composition pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing process of pellets of a thermoplastic resin composition by which high quality pellets are obtained by controlling the condensation or sublimation of the volatile components in the vent of an extruder with a method other than that of cooling the vent from outside. <P>SOLUTION: An inert gas is blown to the vent of an extruder to continuously create an accompanying gas flow toward the exhaust port in manufacturing pellets of a thermoplastic resin composition composed of a thermoplastic resin, an inorganic filler and an additive by melting, kneading, and extruding the composition through the dice of the extruder having a vent mechanism while using the vent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing pellets of a thermoplastic resin composition comprising a thermoplastic resin and an additive, or a thermoplastic resin, an inorganic reinforcing material, and an additive using an extruder. More specifically, the present invention relates to a method for producing a thermoplastic resin composition pellet excellent in quality by suppressing contamination due to a devolatilizing component in a vent portion of an extruder and minimizing oxidation deterioration and contamination with foreign matter.

  For the purpose of modifying a thermoplastic resin, a method of obtaining a resin composition by melting and kneading a thermoplastic resin, an inorganic filler, various additives and the like using an extruder is widely used. Further, when simply coloring (toning) a thermoplastic resin or a resin composition thereof, measures such as melt-kneading a resin component and a dye / pigment with an extruder are often taken.

  For example, a composition comprising a polyester resin, a polycarbonate resin and a phosphorus compound (Patent Document 1), a resin composition comprising a polyamide resin and a hindered phenol or phosphites (Patent Document 2), a polyamide resin, a layered silicate and Composition composed of phosphite compound (Patent Document 3), composition composed of polycarbonate resin, polyester resin, basic inorganic filler and phosphite compound (Patent Document 4), composition composed of polylactic acid resin, polyacetal and release agent Many articles (Patent Document 5) have been proposed.

  When melt-kneading a thermoplastic resin or the like using an extruder, water molecules are removed for the purpose of stabilizing the discharge of the resin composition from the die and suppressing hydrolysis, or low molecular weight compounds for the purpose of improving physical properties and appearance. In order to drive, an extruder equipped with a vent mechanism is often used. The purpose of the vent part of the extruder is to devolatilize low molecular weight components, but since the component devolatilized from the resin composition is condensed or sublimated in the vent part, the vent part is in an environment that is very easily contaminated.

  Since the vent part of such an extruder is not directly wetted by the resin, it is not always cleaned even if it gets dirty, and it must be cleaned intentionally. Cleaning is almost impossible. Therefore, the condensed or sublimated substance stays in the vent portion for a long time, discolors due to oxidation or thermal deterioration, and drops by dropping into the resin, thereby causing a phenomenon that deteriorates the color tone of the resin composition. These phenomena may not only volatilize not only the volatile components contained in the thermoplastic resin, but also the additives added for the purpose of modification, or their decomposition products, especially when using organophosphorus compounds. Is likely to be blackened due to thermal deterioration, so that the dirt on the vent is often significant.

  In particular, in the case of a vacuum type vent, the piping to be evacuated or the like is blocked by a sublimate, and the degree of vacuum at the vent portion is lowered, resulting in a phenomenon that the quality of the resulting resin composition is lowered.

  The low molecular weight component devolatilized from the resin component is condensed or sublimated in the vent part mainly due to the temperature difference between the inside of the cylinder of the extruder and the vent part. This is because when the low molecular weight compound devolatilized below flows to the vent part, it is cooled at the inner wall part of the vent and liquefied or solidified.

  The cylinder part is equipped with a heater and can heat the inside, but one vent part is usually not equipped with a heater, so the temperature of the vent part is the heat from the cylinder in contact. It is only due to conduction and heat transfer from the gas flowing inside, and it is cooler than the cylinder.

Therefore, if a heater is installed in the vent part, it will be possible to heat to the same temperature as the cylinder, but the shape of the vent part is complicated, space problems, and cleaning of the machine base when changing the brand to be manufactured, etc. This is not practical because the work of disassembling the vent portion becomes complicated. Further, if only a part of the vent portion is heated to avoid these problems, the vent portion is likely to be insufficiently heated. Thus, there are various problems in dealing with the heating of the vent part.
JP 2000-327892 A JP 2004-43567 A JP 2002-88239 A JP 2004-359913 A JP 2003-268223 A

  The present invention solves the above problems and suppresses the devolatilizing component from condensing or sublimating inside the vent by a method other than heating the vent portion of the extruder from the outside to obtain a pellet having excellent quality. It is an object of the present invention to provide a method for producing a thermoplastic resin composition pellet that can be produced.

  As a result of intensive studies to solve the above problems, the present inventors have shortened the residence time of the vaporized volatile component in the vent portion of the extruder as much as possible and reduced the partial pressure of the volatile component. As a result, it was found that condensation and sublimation of volatile components were suppressed even when the vent portion was cooler than the cylinder of the extruder. Specifically, the present inventors have reached the present invention by finding that a volatile component is discharged from the vent part without liquefaction or solidification by circulating an inert gas as a carrier gas in the vent part.

That is, the gist of the present invention is as follows.
(1) Thermoplastic that melts and kneads a thermoplastic resin and an additive, or a thermoplastic resin, an inorganic filler, and an additive using a extruder having a vent mechanism and uses a vent part and discharges it from a die. In a method for producing a resin composition pellet, a method for producing a thermoplastic resin composition pellet, characterized in that an inert gas is circulated through a vent portion of an extruder and an accompanying airflow is constantly generated from the vent portion toward an exhaust port. .
(2) The inert gas is selected from rare gases such as helium, neon, argon, and krypton, and saturated hydrocarbons such as nitrogen, carbon dioxide, or less reactive methane, ethane, and propane. The method for producing a thermoplastic resin composition pellet as described in (1) above,
(3) The ratio F / V of the volumetric flow rate F (Nl / min) per minute converted to 0 ° C. and atmospheric pressure of the inert gas and the internal volume V (l) of the extruder vent is 0. It is 5 or more, The manufacturing method of the thermoplastic resin composition pellet as described in said (1) or (2) characterized by the above-mentioned.
(4) The thermoplasticity as described in any one of (1) to (3) above, wherein the pressure of the inert gas is not lower than atmospheric pressure, the temperature is not lower than normal temperature and not higher than the temperature of the resin component in the extruder. Manufacturing method of resin composition pellets.
(5) The thermoplastic resin composition as described in any one of (1) to (4) above, wherein the additive is an organic compound having a melting point or sublimation temperature in the range of 60 to 250 ° C. at atmospheric pressure. Manufacturing method of food pellets.
(6) The method for producing a thermoplastic resin composition pellet according to any one of (1) to (5), wherein the additive is an organic phosphorus compound.

  According to the present invention, an inert gas is circulated through the vent portion without heating the vent portion of the extruder from the outside, and an accompanying airflow is constantly generated from the vent portion toward the exhaust port. It is possible to suppress the dehydration and sublimation of the volatile components and to suppress the deterioration products from mixing into the composition, so it is possible to produce pellets of thermoplastic resin compositions with excellent quality The industrial utility value is extremely high.

  Hereinafter, the present invention will be described in detail.

  First, the thermoplastic resin used in the present invention is a thermoplastic resin that can be pelletized by a melt extruder, such as polycarbonate, polyamide (nylon 6, nylon 66, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate). , Liquid crystal polymer, etc.), polyarylate, polyamideimide, polyphenylene sulfide, polyacetal, polyolefin resin (polyethylene, polypropylene, etc.), polystyrene, polyvinyl chloride, polyvinylidene chloride resin, acrylonitrile / styrene / butadiene copolymer, etc. Illustrated. These thermoplastic resins may be used singly or may be a mixture of a plurality of them as long as the mechanical properties are not impaired. There is no restriction | limiting in particular in the shape of a thermoplastic resin, The thing of arbitrary shapes, such as a powder form, a pellet form, and flake form, can be used.

  Additives include lubricants, nucleating agents, plasticizers, thickeners, flame retardants, processing stabilizers, antioxidants, ultraviolet absorbers, mold release agents, colorants, antistatic agents, surface treatment agents, and crosslinking agents. Examples thereof include all additives that can be kneaded with a thermoplastic resin, such as an agent, a coupling agent, and polytetrafluoroethylene for improving sliding properties, and a rubber-like resin for improving impact properties.

  The additives mentioned above are generally low molecular weight organic compounds other than polytetrafluoroethylene and rubber-like resins, and their melting points are not so high, or some substances sublime without melting. . In particular, since the boiling point decreases under vacuum, it is devolatilized by a vacuum vent when melt-kneaded with a thermoplastic resin in an extruder. Thus, the additive that can be devolatilized by the vacuum vent cannot be generally described because the temperature at which it is melt-kneaded varies depending on the type of thermoplastic resin, but the melting point or sublimation temperature at atmospheric pressure is in the range of 60 to 250 ° C. Since they are condensed or sublimated at the vent as will be described later, application of the present invention is effective.

  In addition, among the above additives, organophosphorus compounds that are often used for antioxidants and flame retardants are easily blackened due to thermal deterioration, so the method for producing the thermoplastic resin composition pellets of the present invention is effectively used. it can.

  Next, inorganic fillers include whisker, fibrid, glass fiber, carbon fiber, alumina fiber, silicon carbide fiber, boron fiber, titanium fiber, and other fibrous reinforcing materials, smectite minerals, vulcanite minerals, mica Examples thereof include talc, clay, glass beads, glass balloons, carbon black, etc., in addition to plate-like or layered reinforcing materials such as minerals, brittle mica series minerals, chlorite minerals, and graphite.

  The extruder used in the present invention can be extruded by melting and kneading a thermoplastic resin, and has a devolatilization mechanism (vent part) for removing volatile components contained in the raw material resin during melt kneading. However, it is preferable to use a twin-screw extruder when kneading a plurality of types of thermoplastic resins or dispersing an inorganic filler, and the rotational direction of the screw is the same. The direction is more preferable because a resin composition with excellent quality can be obtained.

  Further, the number of vent parts per extruder is not particularly limited, but in the case of a twin screw extruder, it is preferable to change according to the number of kneading stages of the thermoplastic resin, and the number of vents of 1 to 3 stages. Are preferably used. In order to remove what is contained in the raw material components and volatile components generated by melt-kneading, it is preferable that the vent portion is depressurized from atmospheric pressure, particularly when using a thermoplastic resin having an ester bond in the main chain, A high vacuum is preferred to prevent low molecular weight due to hydrolysis.

  As described above, the purpose of the vent part of the extruder is to devolatilize low molecular weight components, but the component devolatilized from the resin composition in the extruder is condensed or sublimated on the inner wall of the vent part, so the vent part is very It is easy to get dirty. Since these substances remain in the vent portion for a long time, they are likely to be thermally deteriorated, and they may drop or drop into the resin and deteriorate the quality of the resin composition. In addition, a sublimation product may block a pipe or the like that is evacuated from the vent portion, so that the vent portion cannot be maintained under a substantial vacuum, and a resin composition with good quality may not be obtained.

  In order to solve the above problem, the gist of the present invention is to circulate an inert gas through a vent part, preferably a vacuum type vent part, and always generate an accompanying air flow from the vent part toward the exhaust port. . That is, when an inert gas is circulated, an accompanying airflow is always generated in the vent portion, so that the vaporized volatile component is immediately removed from the vent portion by the accompanying airflow, and the partial pressure of the devolatilized component is reduced. It is possible to suppress dew condensation and sublimation in the vent part and piping to be evacuated, etc., and it is possible to prevent deterioration of the quality of the thermoplastic resin because these deteriorated substances are reduced from being mixed into the composition. Become.

  The shape of the vent is not particularly limited as long as an inert gas can be introduced, but between the vicinity of the screw that penetrates the inside of the extruder barrel and the portion connecting the vacuum exhaust pipe of the vent. Providing an inflow port is preferable because the direction of the airflow generated inside the vent is from the inside of the extruder toward the vacuum exhaust system.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a vent portion of an extruder used in the present invention. In FIG. 1, the inert gas is supplied to the inside of the vent from an inert gas introduction pipe 3 penetrating the lid 2 of the vent portion, and is always discharged as an accompanying airflow from the vacuum exhaust port 4. At that time, the component devolatilized from the resin composition in the extruder is discharged from the vacuum exhaust port 4 together with the accompanying air flow, and does not condense on the inner wall of the vent portion. In the figure, 1 is a vent body, 5 is a barrel of an extruder, and 6 is a screw of the extruder.

  In the case of a so-called open type vent that does not depressurize the vent part to a vacuum, low molecular weight components from the resin composition are not devolatilized as in the case of the vacuum vent, but not only the inside of the extruder vent but also the resin in the barrel. Oxygen oxidation occurs in contact with air. In order to prevent this, it is preferable to circulate an inert gas even in the case of an open type vent.

  The inert gas used in the present invention is a low molecular weight substance that does not act on thermoplastic resins and additives, specifically, rare gases such as helium, neon, argon, krypton, nitrogen, carbon dioxide, or reactivity Saturated hydrocarbons such as methane, ethane, and propane having a low content. Furthermore, in the case of a thermoplastic resin such as polyolefin which does not cause a reduction in molecular weight due to hydrolysis, water vapor can also be used. Among these, nitrogen can be most preferably used from the viewpoint of safety and convenience.

  When the flow rate of the inert gas flowing through the vent part of the extruder is higher, dirt and blockage of the vent part and the vacuum exhaust system are less likely to occur, but if the flow rate is too high, the vent part is vacuum depressurized. Since the degree of vacuum deteriorates, the devolatilizing ability, which is the original purpose of the vent part, is lowered, which is not good. Therefore, it is preferable to appropriately adjust the flow rate of the inert gas so that the degree of vacuum of the vent portion is not significantly impaired. Specifically, the ratio F / V between the volume flow rate F (Nl / min) per minute converted to 0 ° C. and atmospheric pressure and the internal volume V (l) of the extruder vent is 0.5 or more. It is preferable to set it as 1.0, and it is more preferable to set it as the range of 1.0-10.0. When F / V is less than 0.5, the flow rate of the inert gas is small, and the residence time of the inert gas inside the vent may become long, and a sufficient effect may not be obtained. In some cases, the degree of vacuum cannot be achieved, or a large vacuum evacuation device is required to reduce the degree of vacuum, which is impractical.

  The inert gas flowing through the vent portion of the extruder is preferably at a pressure of atmospheric pressure or higher and a gauge pressure of 1.0 MPa or lower. On the other hand, if the pressure of the inert gas is lower than the atmospheric pressure, air may enter from the joints of pipes and the like, which may cause oxidative deterioration of the resin component in the extruder, which is not preferable.

  The temperature of the inert gas is preferably normal temperature or higher and lower than the temperature of the resin component in the extruder. When the temperature of the inert gas is too low, the vent part is cooled, and condensation or sublimation of the devolatilized component is likely to occur. Conversely, when the temperature is too high, the resin component staying in the vicinity of the vent part is thermally deteriorated. This is not preferable.

  The thermoplastic resin, additives, and inorganic filler are usually supplied to the most base side to the extruder. However, the raw material components are sequentially supplied and kneaded, or a fibrous or plate-like reinforcing material. In order to prevent the damage, one side or several stages of side feeders may be provided in the middle of the extruder, and a part of the raw material components or all of the specific components may be supplied therefrom. Furthermore, you may supply a liquid component from the injection | pouring mechanism provided in the middle of the extruder.

In the present invention, the extrusion temperature of the extruder is not particularly limited as long as it is a temperature at which the thermoplastic resin melts, but yellowing of the color tone of the resin composition obtained by reducing the temperature as much as possible is easily suppressed. preferable.

EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited only to an Example. In addition, the raw material used in the Example and the vent part shape of an extruder are as follows.
1. Raw materials used (1) Polyamide 6
Unitika nylon resin A1030BRL: hereinafter referred to as “PA”.
(2) Polyarylate U polymer D-powder manufactured by Unitika. Hereinafter, it is referred to as “PAR”.
(3) Polycarbonate Caliber 200-3 manufactured by Sumitomo Dow. Hereinafter, it is referred to as “PC”.
(4) Heat stabilizer Adeka Stub PEP-24G (melting point: 170 ° C.) manufactured by Asahi Denka Co., Ltd.
(5) Mold release agent LUVAX1266 (melting point 69 ° C) manufactured by Nippon Seiwa Co., Ltd.
(6) Glass fiber Chopped strand T-289 manufactured by Nippon Electric Glass Co., Ltd. Hereinafter referred to as “GF”.
2. Vent Part Shape of Extruder As shown in FIG. 1, a vacuum type having an inert gas introduction pipe 3 provided on the lid 2 of the vent part was used. The tip of the inert gas introduction pipe 3 was positioned between the upper part of the extruder screw 6 and the vacuum exhaust port 4.

(Example 1)
After 100 parts by weight of PA and 0.5 parts by weight of heat stabilizer PEP-24G are uniformly mixed, a twin-screw extrusion manufactured by Toshiba Machine Co., Ltd. is used with a loss-in-weight twin-screw meter CE-W-1 manufactured by Kubota. TEM-37BS was supplied to the main supply port. This twin-screw extruder is provided with a vent portion having an approximate internal volume of 1 liter only at one location before the die portion, and nitrogen gas (pressure 0. 3 MPa, temperature 25 ° C.) at a flow rate of 1 Nl / min (F / V = 1).

Melting and kneading were performed at a screw speed of 200 rpm, a discharge rate of 15 kg / h, and a barrel temperature setting of 250 ° C., and the resin composition taken up in a strand form from the die orifice was cooled and solidified through a water bath to obtain resin composition pellets. Extrusion was continued for 1 hour, but the degree of vacuum in the vent was maintained at a gauge pressure of -0.098 MPa throughout. Thereafter, the material supply device was stopped, the extruder was stopped, and the state inside the vent was confirmed. As a result, no sublimated material was seen on the inner wall, and the material was in a dry state.

The obtained resin composition pellets are molded at a cylinder temperature of 250 ° C. using an IS80G injection molding machine manufactured by Toshiba Machine Co., Ltd., to produce a sample plate having a thickness of 1 mm, and a color tone measuring device (Nippon Denshoku SE-2000) Was used to measure the yellow index, which was 16.9.

(Example 2)
Pellets of a resin composition were obtained in the same manner as in Example 1 except that 69 parts by mass of PAR, 29 parts by mass of PC, and 2 parts by mass of release agent LUVAX1266 were used and the barrel temperature was set to 320 ° C. When the extrusion was continued for 1 hour, the vacuum level was maintained at -0.098 MPa, and after the extruder was stopped, the condition inside the vent was checked. As a result, no sublimated material was seen on the inner wall, and the condition was dry. It was.

The obtained resin composition pellets are molded at a cylinder temperature of 320 ° C. using an IS80G injection molding machine manufactured by Toshiba Machine Co., Ltd., to produce a sample plate having a thickness of 3 mm. Was used to measure the yellow index, which was 11.2.

(Example 3)
Using a separate loss-in-weight type twin screw meter CE-W-1 manufactured by Kubota Corporation, 85 parts by mass of PA and 0.5 parts by mass of the heat stabilizer PEP-24G and 15 parts by mass of GF were separately used. Each was supplied to the main supply port and side feeder of a twin screw extruder TEM-37BS manufactured by Toshiba Machine. This twin-screw extruder is provided with vents with an estimated internal volume of 1 liter at two locations before the die part and before the side feeder. Nitrogen gas from the inert gas introduction pipe is reduced to vacuum. (Pressure 0.3 MPa, temperature 25 ° C.) was circulated at a flow rate of 1 Nl / min (F / V = 1).

Melting and kneading were performed at a screw rotation speed of 200 rpm, a total discharge rate of 15 kg / h, and a barrel temperature setting of 250 ° C., and the resin composition taken up in a strand form from the die orifice was cooled and solidified through a water bath to obtain resin composition pellets. Extrusion was continued for 1 hour, but the vacuum level of the vent was maintained at a gauge pressure of -0.098 MPa throughout. Thereafter, the raw material supply device was stopped, the extruder was stopped, and the state inside the vent was confirmed. As a result, no sublimated material was seen on the inner wall, and the material was dry.

The yellow index was measured in the same manner as in Example 1 and found to be 17.3.

(Comparative Example 1)
Pellets of the resin composition were obtained in the same manner as in Example 1 except that 100 parts by mass of PA and 0.5 parts by mass of the heat stabilizer PEP-24G were used and nitrogen gas was not passed through the vent part. Forty minutes after the start of extrusion, the vacuum was maintained at a gauge pressure of -0.098 MPa, but a brown-colored strand suddenly developed. When the state inside the vent was confirmed after the extruder was stopped, a black liquid adhered to the inner wall.

The obtained resin composition pellets were molded at a cylinder temperature of 250 ° C. using an injection molding machine IS80G manufactured by Toshiba Machine Co., Ltd., to produce a sample plate having a thickness of 1 mm. Was used to measure the yellow index, which was 23.5.

(Comparative Example 2)
Pellets of a resin composition were obtained in the same manner as in Example 2 except that PAR69 parts by mass, PC29 parts and release agent LUVAX1266: 2 parts by mass were used, and nitrogen gas was not passed through the vent part. Thirty minutes after the start of extrusion, the degree of vacuum dropped to a gauge pressure of -0.05 MPa, and the strands became white and foamed. When the state inside the vent was confirmed after the extruder was stopped, white sublimate was adhered to the inner wall, and the vacuum exhaust pipe was almost clogged with white solid matter.

The obtained resin composition pellets are molded at a cylinder temperature of 320 ° C. using an IS80G injection molding machine manufactured by Toshiba Machine Co., Ltd., to produce a 3 mm-thick sample plate, and a color tone measuring device (Nippon Denshoku SE-2000) Was used to measure the yellow index, which was 13.3.

(Comparative Example 3)
A pellet of a resin composition was obtained in the same manner as in Example 3 except that 85 parts by mass of PA, 0.5 part by mass of the heat stabilizer PEP-24G and 15 parts by mass of GF were used and nitrogen gas was not passed through the vent part. It was. From the start of extrusion, the gauge was maintained at a gauge pressure of -0.098 MPa from the beginning to the end, but after 30 minutes from the start, the color of the strand was slightly brown. When the state inside the vent was checked after the extruder was stopped, black liquid adhered to the inner wall at both locations.

The obtained resin composition pellets were molded at a cylinder temperature of 250 ° C. using an injection molding machine IS80G manufactured by Toshiba Machine Co., Ltd., to produce a sample plate having a thickness of 1 mm. Was used to measure the yellow index, which was 28.9.

(Comparative Example 4)
Using 100 parts by mass of PA and 0.5 parts by mass of the heat stabilizer PEP-24G, air (pressure 0.2 MPa, temperature 25 ° C.) was reduced to 1 Nl / min (F / V = 1) while the vent part was evacuated to a vacuum. Resin composition pellets were obtained in the same manner as in Example 1 except that the resin composition was distributed at a flow rate. A yellow color was observed in the strand from the beginning of extrusion. Extrusion was continued for 1 hour, but the degree of vacuum in the vent was maintained at a gauge pressure of -0.098 MPa throughout. Thereafter, the raw material supply device was stopped, the extruder was stopped, and the state inside the vent was confirmed. As a result, no sublimated material was seen on the inner wall, and the material was dry.

The obtained resin composition pellets are molded at a cylinder temperature of 250 ° C. using an IS80G injection molding machine manufactured by Toshiba Machine Co., Ltd., to produce a sample plate having a thickness of 1 mm, and a color tone measuring device (Nippon Denshoku SE-2000) Was used to measure the yellow index, which was 19.6.

The difference between the above-described Examples 1 to 3 and the corresponding Comparative Examples 1 to 3 is the presence or absence of nitrogen gas supply to the vent part, but was obtained in Examples 1 to 3 in which nitrogen gas was supplied to the vent part. The yellow index of the sample plate was smaller than that of the corresponding Comparative Examples 1 to 3, and less yellowed. Further, the difference between Example 1 and Comparative Example 4 is that the gas supplied to the vent portion is different, but the yellow index of the sample plate obtained in Example 1 supplied with nitrogen gas supplied air. The value was smaller than that of Comparative Example 4, and the yellowing was less.

It is a schematic sectional drawing which shows one embodiment of the vent part of the extruder used by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vent part main body 2 Vent part cover 3 Inert gas introduction pipe 4 Vacuum exhaust port 5 Barrel of extruder 6 Screw of extruder

Claims (6)

   A thermoplastic resin composition in which a thermoplastic resin and an additive, or a thermoplastic resin, an inorganic filler, and an additive are melt-kneaded and discharged from a die using an extruder having a vent mechanism while using a vent portion. In the manufacturing method of a pellet, the inert gas is distribute | circulated to the vent part of an extruder, and an accompanying airflow is always generated toward an exhaust port from a vent part, The manufacturing method of the thermoplastic resin composition pellet characterized by the above-mentioned.   The inert gas is selected from rare gases such as helium, neon, argon, and krypton, and saturated hydrocarbons such as nitrogen, carbon dioxide, or less reactive methane, ethane, and propane. The manufacturing method of the thermoplastic resin composition pellet of Claim 1.   The ratio F / V between the volume flow rate F (Nl / min) per minute converted to 0 ° C and atmospheric pressure of the inert gas and the internal volume V (l) of the extruder vent is 0.5 or more. The method for producing a thermoplastic resin composition pellet according to claim 1, wherein the thermoplastic resin composition pellet is present.   The production of the thermoplastic resin composition pellets according to any one of claims 1 to 3, wherein the pressure of the inert gas is equal to or higher than atmospheric pressure, the temperature is equal to or higher than normal temperature, and is equal to or lower than the temperature of the resin component in the extruder. Method.   The method for producing a thermoplastic resin composition pellet according to any one of claims 1 to 4, wherein the additive is an organic compound having a melting point or sublimation temperature in the range of 60 to 250 ° C at atmospheric pressure. The method for producing a thermoplastic resin composition pellet according to any one of claims 1 to 5, wherein the additive is an organic phosphorus compound.