JP2002292626A - Method for manufacture of thermoplastic resin pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacture of a thermoplastic resin pellet which is excellent in quality wherein foreign matter such as a gelling material, carbide and the like is little by improving a conveying capacity and a self screening capacity of a double axes extruder while a method for manufacture of a polyamideimide resin pellet is especially provided. SOLUTION: When a thermoplastic resin pellet is manufactured by using a bent type double axes extruder, a melt-conveying area is shortened by carrying out a cylinder and screw arrangement without substantially providing a vacuum degassing area, and an attendant air amount to a transfer area is decreased by providing an extruding material-compressing area in a solid conveying area to control generation of a carbide. Further, by feeding the thermoplastic resin pellet having the almost same composition as that of thermoplastic resin pellet to be discharged by being melted and kneaded, a powder conveying capacity and a self screening capacity in the transfer area are improved to control the generation of the carbide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of melting a thermoplastic resin or a thermoplastic resin and additives using a twin screw extruder.
The present invention relates to a method for producing a thermoplastic resin pellet by kneading. More specifically, it is a technology to improve the conveying capacity and self-cleaning capacity of a twin-screw extruder and to suppress the generation of gelled materials and carbides. It relates to a manufacturing method.
In particular, it relates to a method for producing polyamide-imide resin pellets.

[0002]

2. Description of the Related Art When thermoplastic resin pellets are produced by melting and kneading using a twin-screw extruder, air accompanying the extruded material (hereinafter referred to as "associated air"), shear heat generated by screw rotation, extruder cylinder and screw In some cases, the extruded material may be oxidized or thermally decomposed to produce a gelled substance or carbide (hereinafter referred to as carbide) due to the stagnation portion caused by the shape of the material, and the extruded material may be mixed into pellets as a product.

As a countermeasure, a filter is generally provided inside the tip of the cylinder on the discharge side of the twin-screw extruder for the purpose of filtering and removing generated carbide, and the filter is regularly replaced.

As a countermeasure against oxidation by accompanying air, Japanese Patent Publication No. 6-206216 discloses a technique for suppressing the formation of carbides by supplying nitrogen gas from a supply port of an extruder and reducing the oxygen concentration. ing.

[0005] As a screw shape having a small staying part,
There is a screw of a completely meshing type of a double-groove double-thread screw called a self-cleaning type. Regarding this screw shape, for example, Japanese Patent Application Laid-Open No. 8-258110 discloses a technique of improving the self-cleaning property by changing the thickness of the tip end of a screw flight between a first screw and a second screw. ing.

[0006] As a technique for improving the ability to convey a powdery material, for example, Japanese Patent Application Laid-Open Nos. 6-166082 and 2000-25094 disclose an air bleeding device of an extruder and deaeration of contained air. Means for feeding the material are disclosed.

[0007] Also, Japanese Patent Application Laid-Open No. 5-286011 discloses that
A method in which a powder is compressed and supplied by providing a screw in a hopper cylinder, and a method in which a material powder is classified by a vibrating sieve before feeding into an extruder is disclosed in JP-A-11-291323. I have.

Japanese Patent Application Laid-Open No. Hei 10-180840 discloses a screw shape for improving the ability to transport powdery materials, and Japanese Utility Model Application Laid-Open No. Hei 6-68815 discloses a method for increasing the flight width of a full flight screw. A screw structure for reducing leakage flow is disclosed.

In order to effectively perform devolatilization, a twin-screw extruder is generally provided with a vent hole in a cylinder.

[0010]

The method of providing a filter for removing carbides not only requires complicated replacement of the filter but also makes it impossible to install the filter with a resin having a high melt viscosity such as a polyamideimide resin. In addition, it was necessary to frequently clean the screw and the cylinder.

Further, in the method of supplying nitrogen gas, if nitrogen gas is supplied only to replace the accompanying air, the material tends to cause a phenomenon that the material flows up the screw flow path to the backflow / supply port, so that the carrying capacity is reduced and improper. In some cases, a phenomenon in which the ejection of the molten resin becomes stable and the ejection of the molten resin becomes unstable is caused. In particular, when the material is a powder, it tends to lead to a decrease in the carrying capacity and an unstable discharge.

[0012] Even in the case of a screw called a self-cleaning type, there is a gap between the screws to avoid friction and abrasion due to the rotation of the twin screw. However, it was insufficient to prevent adhesion of the molten resin to the cylinder surface.

Further, Japanese Patent Application Laid-Open Nos. 6-166082, 2000-25094, 5-28601
No. 1, JP-A-11-291323, JP-A-11-291323
The methods for improving the transfer capacity described in Japanese Patent Application Laid-Open Nos. 0-180840 and 6-68815 not only have drawbacks such as a complicated process or lack of versatility, but also have a disadvantage in preventing carbide. Was less effective.

Further, when the vent hole is provided, the cylinder itself becomes longer, and the total amount of the deposited molten resin increases.
The connection surface / mounting surface of the vent hole became a stagnation portion of the molten resin, and sometimes increased the amount of carbide.

Further, since the vent hole is mainly intended for devolatilization, there is a problem that the devolatilization of the material becomes insufficient and the discharge becomes unstable if only the vent hole is not provided.

In view of the above problems, an object of the present invention is to melt and knead a thermoplastic resin material using a twin screw extruder,
It is an object of the present invention to provide a method for producing a thermoplastic resin pellet, which is a method for producing a thermoplastic resin pellet, which effectively suppresses the generation of carbides.

[0017]

That is, the present invention comprises the following. (1) A method for producing a thermoplastic resin or a thermoplastic resin pellet which is melted and kneaded with a thermoplastic resin and an additive and discharged from a die using a twin-screw extruder. A method for producing a thermoplastic resin pellet, comprising regions A to C. A. In the twin-screw extruder, a thermoplastic resin glass including a compression region provided with a screw element serving as a compression / pressurization region of a thermoplastic resin and a pressure reduction region provided with a screw element for reducing pressure following the compression region A transport region preheated at a temperature lower than the transition temperature (Tg) or lower than the melting point (Tm) and at which the thermoplastic resin does not substantially melt. B. Transition region where the thermoplastic resin melts. C. A molten resin conveying region formed substantially in contact with the molten resin discharge mouth side in a region where there is substantially no vacuum devolatilization region and the free volume filling rate of the molten resin in the cylinder substantially approaches 100%. (2) In producing a thermoplastic resin pellet by melting and kneading a thermoplastic resin or a thermoplastic resin and an additive using a twin-screw extruder, the thermoplastic resin pellet is melted, kneaded and discharged. The thermoplastic resin pellets having the same composition are supplied from the supply port to 1/100 of the molten resin discharge amount of the extruder.
A method for producing thermoplastic resin pellets, comprising supplying at a ratio corresponding to 1000 to 1/2. (3) The thermoplastic resin pellets having substantially the same composition as the thermoplastic resin pellets that are melted and kneaded and discharged are supplied from the supply port to 1/1000 to 1/100 of the molten resin discharge amount of the extruder.
It is characterized in that it is supplied at a rate corresponding to 2. (1)
A method for producing the thermoplastic resin pellet according to the above. (4) The thermoplastic resin is in the form of a powder, and (a) the powder has an average particle diameter of 0.1 to 700 μm, or (b) a bulk density of 0.1 to 0.8 g / ml. The method for producing a thermoplastic resin pellet according to any one of (1) to (3), which is a powder. (5) The thermoplastic resin has the following general formula (I)

[0018]

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(Wherein, R is a divalent aromatic residue and / or an aliphatic residue) is a polyamideimide resin powder having a repeating unit represented by the following formula as a main structural unit. The method for producing a thermoplastic resin pellet according to any one of 1) to (4).

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
FIG. 1 shows an example of a twin-screw extruder used in the present invention. In FIG. 1, 1 is a cylinder of an extruder, 2 is a screw, 3 is a discharge mouthpiece, 4 and 5 are first and second supply ports, 6 is a devolatilization port, and the pressure is raised and melted in a transition region 9. The outlet of the associated air that has flowed back along with it. Reference numeral 7 denotes a compression region which is a compression / pressure increase region of the thermoplastic resin, and reference numeral 8 denotes a pressure reduction region.

FIG. 1 shows the solid transportation (area).
The transfer region preheated at a temperature at which the thermoplastic resin of the present invention does not substantially melt is a solid transfer region including at least the regions 7 and 8, and in this example, the block from the block having the first supply port to the transfer region 8 Point to the area up to. Reference numeral 9 denotes a transition region in which the pressure is raised and melted, 10 denotes a melting / kneading region, and 11 denotes a molten resin transport region in which a free volume of the molten resin is substantially close to 100%.

In the solid conveying area in FIG. 1, preheating is performed at a temperature at which the thermoplastic resin does not melt. Here, the method of preheating at a temperature at which the thermoplastic resin does not substantially melt is not particularly limited. For example, by setting the cylinder temperature to be lower than the melting point (Tm) of the thermoplastic resin or lower than the glass transition temperature (Tg). The temperature is set by setting a cylinder temperature at which the thermoplastic resin to be conveyed does not melt even when the amount of heat generated by shearing and the amount of heat generated by screw rotation are combined.

Further, the molten resin conveying regions 9 to 11 have no vent holes and the like, and have substantially no vacuum devolatilizing region.

Next, FIG. 2 shows an example of a conventional twin-screw extruder (used as an example and a comparative example). In FIG.
Is the same as FIG.

Reference numeral 12 denotes a degassing port in a region where the resin is melted, which is also used as an open degassing port or a supply port, for removing and discharging volatile components and residual monomers and oligomers by vacuum devolatilization.

13 is a transition region where the pressure is raised and melted, 14 is a region where the filling ratio of the molten resin in the free volume in the cylinder is substantially close to 100%, 15 is a region where the pressure of the resin once raised and melted is reduced, Reference numeral 16 denotes a pressure rising region, and reference numeral 17 denotes a region where the filling ratio of the molten resin in the free volume becomes substantially close to 100% again.

Here, the molten resin transport area is 13 to 17, and a vent hole (vacuum devolatilization port) 12 is provided in the molten resin transport area.

In FIG. 1 and FIG. 2, the screw element serving as the compression region and the transition region of the thermoplastic resin is, for example, a taper (deep groove → shallow groove) in the case of a triple thread type.
In the case of a screw, a shallow groove screw, and a double-start screw type, a reverse screw, a screw arrangement in which the lead length is gradually shortened, or a kneading screw is preferably used. When the raw material is a powder, the reverse screw used in the compression region preferably has a small screw diameter, that is, a flight height.

As the screw element serving as the pressure-reducing region, for example, a reverse taper (shallow groove → deep groove) screw in the case of a three-start screw type, a deep groove screw, a screw arrangement in which the lead length is gradually increased in the case of a double-start screw type, etc. Is preferably used.

The screw element serving as the melting / kneading region is, for example, a shallow groove screw in the case of a three-thread screw type, a reverse screw, a screw having a short lead length, or a kneading screw in the case of a two-thread screw type. Is preferably used.

As the screw element in the molten resin conveying area, for example, a shallow groove screw in the case of a triple screw type, a screw having a short lead length, and a screw having a short lead length in the case of a double screw type are preferably used. .

In the present invention, the thermoplastic resin is a thermoplastic resin that can be pelletized by a melt extruder, for example, polyamide imide, polyphenylene sulfide, polycarbonate, polyolefin resin (polyethylene, polypropylene, etc.), polystyrene Polyvinylidene chloride resin, polyamide (nylon 6, nylon 66, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, liquid crystal polymer, etc.), polyacetal, acrylonitrile / styrene / butadiene copolymer and the like.

In particular, a polyamideimide resin is preferably used.

The shape of the thermoplastic resin is not particularly limited.
Any shape such as a powder, a pellet, and a flake can be used, but a powdery raw material is preferably used.

The additives include, for example, glass beads,
Inorganic fillers such as glass flakes, talc, mica, and titanium dioxide, lubricants, nucleating agents, plasticizers, flame retardants, processing stabilizers, antioxidants, ultraviolet absorbers, release agents, coloring agents, antistatic agents, surfaces It can be kneaded with a thermoplastic resin such as a treating agent, a crosslinking agent, a coupling agent, and a second component thermoplastic resin such as polytetrafluoroethylene for improving slidability, and a rubber-like resin for improving impact resistance. Say all additives.

Next, thermoplastic resin pellets having substantially the same composition as the thermoplastic resin pellets to be discharged after being melted and kneaded are supplied from the supply port to a 1/1 of the molten resin discharge amount of the extruder.
A method for producing thermoplastic resin pellets, characterized in that the pellets are supplied at a rate corresponding to 000 to ２, will be described.

The thermoplastic resin pellets having substantially the same composition as the thermoplastic resin discharged after being melted and kneaded are pellets having substantially the same composition as the resin discharged from the die die by operating the extruder. What is necessary is just to use, for example, the discharged resin itself, and a resin to which an additive or the like is added. Of course, it may be separately manufactured.

By supplying thermoplastic resin pellets having substantially the same composition as the thermoplastic resin discharged after being melted and kneaded, self-cleaning properties can be improved and carbides can be reduced. The method of supplying the pellets is not particularly limited, but it is preferable that the pellets are supplied from a supply port located upstream (on the side of the drive motor) of a transition region (9 in FIG. 1) formed in the extruder. The number of supply ports is not particularly limited as long as it is supplied from one or more supply ports.

The supply amount of the thermoplastic resin pellet having substantially the same composition as the thermoplastic resin discharged after being melted and kneaded is 1/1000 to 1/2 of the molten resin discharge amount of the extruder.
And preferably 1/500 to 1/500.
3, more preferably 1/100 to 1/4. 1/1
If it is less than 000, the effect of suppressing carbide is small, and if it exceeds １ ／, the productivity is lowered, which is not preferable.

The thermoplastic resin used in the present invention is preferably in a powder form, and has an average particle diameter of 0.1 to 70.
It is preferable that the powder has a particle diameter of 0 μm or a bulk density of 0.1 to 0.8 g / ml. By using a powdery raw material, the carbide suppressing effect of the present invention is more remarkably exhibited.

Here, the average particle diameter and the bulk density are values determined by the following methods. The average particle size was determined by measuring the particle size distribution of the powder in accordance with JIS Z8801. That is, it is calculated from the sieving weight of the used sieve and the nominal size of the sieve. Specifically, for example, in a call (mesh) of a Tyler sieve, # 24 / # 32 / # 48 / # 60 / #
Dry mechanical vibration sieving is performed for 10 minutes using a 200 / # 270 sieve, and the weight fraction on each sieve is determined.
The weight fraction of the sieve and the nominal opening of each sieve (mm)
0.701 / 0.495 / 0.295 / 0.246 /
The average particle diameter was calculated from 0.074 / 0.053.

The bulk density is a value determined according to JIS K6891.

As the thermoplastic resin of the present invention, it is more preferable to use a polyamideimide resin powder. Here, as the polyamideimide resin, the following general formula (I)
(In the formula, R is a divalent aromatic residue and / or an aliphatic residue. Here, specific examples of the divalent aromatic residue and / or the aliphatic residue include the following general formula (II) and the like. And a repeating unit represented by the following formula (1) can be used as a main structural unit.

[0044]

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[0045]

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By using the polyamideimide resin powder, the carbide suppressing effect of the present invention can be more remarkably exhibited.

[0047]

The present invention will be specifically described below with reference to examples and comparative examples.

First, the evaluation method of the obtained pellet is described.
I do. As a method for evaluating the carbide suppressing effect of the present invention
Is the amount of carbide mixed in the obtained thermoplastic resin pellets.
A measurement was made. Method for measuring the amount of carbide mixed in pellets
Is based on a foreign matter measurement chart manufactured by the former Ministry of Finance Printing Bureau.
0.08-0.5mm ^TwoOf a size equivalent to
Is a carbide (small) and pelletized per 50g pellet
Pellets with one or more carbides (small) on the surface
The number was counted.

The pellets of 50 g were sampled after the start of the operation in the extruder in the following Examples and Comparative Examples, under the operating conditions where the discharge rate was about 25 kg / h, and after the continuous two hours of operation. Was used.

As an index of the kneading effect, the specific energy (motor power of the extruder per discharge amount: Kwh / kg) is calculated, and the tensile strength of the obtained pellet is determined by AST.
It was measured according to M638.

Further, the amount of the volatile matter remaining in the pellet was compared by measuring the loss on heating of the pellet. Regarding the polyamide-imide resin in the following Examples and Comparative Examples, the weight of the pellets decreased by heating at 340 ° C. for 2 hours using a hot air dryer (HIGHTEMP OVEN HPS-222 / TABAI MFG.CO., LTD). The value was measured and evaluated as residual volatile matter.

Example 1: Example (1) of the present invention (1) The material used was a polyamide-imide resin powder,
Those having an average particle size of 0.39 mm and a bulk density of 0.34 g / ml were used.

The polyamide-imide resin has, as a main structural unit, a repeating unit represented by the general formula (I) (wherein, R is a divalent aromatic residue and / or an aliphatic residue). A polyamideimide having both a structural unit in which R as a divalent aromatic residue is the following structural unit A and a structural unit in which B is A, wherein A is 70 mol% and B is 30 mol% Resin was used.

[0054]

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As an additive, 3% by weight of titanium dioxide TR700 (manufactured by Fuji Titanium Industry Co., Ltd.) was added as a powdery inorganic filler.

The structure of the twin-screw extruder used is composed of nine block cylinders shown in FIG. 1, with supply ports in the first and second block cylinders, and with the sixth block cylinder. A co-rotating twin-screw extruder having a double-screw type screw (diameter: 56 mm, length: 1625 mm) having an air port (however, natural exhaust instead of so-called forced vent and natural exhaust) was used.

First cylinder supply port (first supply port)
, 25 kg / h of polyamide-imide resin powder, and 0.75 kg / h of titanium oxide from the second cylinder supply port (second supply port).

The arrangement of the screws is a full flight screw arrangement from the driving end of the screw (same as the driving end of the cylinder) to 720 mm, and from 720 mm to 90 mm.
Up to 0 mm (compression region), a full flight screw and a small screw outer diameter (5) in which the screw pitch gradually decreases along the extrusion direction so as to compress the powder.
3mm) Arrange the reverse screw, from 900mm to 12mm
Up to 60 mm (pressure reduction area) is a full flight screw arrangement, and from 1260 mm to 1350 mm (transition area), a screw element with a gradually decreasing screw pitch and a screw element arrangement for melting and kneading using a kneading screw. And from 1350mm to 144
Kneading area after melting up to 5 mm, from 1445 mm to 162
Up to 5 mm (the molten resin transport region), a screw arrangement was used in which the extrusion pressure was generated by gradually decreasing the screw pitch with a full flight screw.

Cylinder set temperature corresponding to the region where the resin is melted and kneaded is set to 330 ° C., and cylinder set temperature corresponding to the solid transfer region is set to 200 ° C. under external heating conditions.
The discharge amount (25 k
g / h) was adjusted within the range where stable discharge was possible (at approximately 200 rpm).

The cutting method of the discharged resin was a hot cut method, and cylindrical pellets having a diameter of 2.5 mm and a length of 2.5 mm were obtained.
It was ± 0.02 mm for 5 mm. ).

Comparative Example 1: The twin screw extruder used was composed of nine block cylinders as shown in FIG. 2, the first and second block cylinders had supply ports, and the sixth A co-rotating twin-screw extruder of a double thread type screw (diameter 56 mm, length 1625 mm) having a deaeration port 12 in a region where the resin was melted in the block cylinder was used.

In the arrangement of the screws, since the vacuum forcible devolatilization is performed at the deaeration port 12, the screw pitch gradually decreases along the extrusion direction from the driving end of the screw (same as the driving end of the barrel) to 540 mm. The screw arrangement was such that the full flight screws were arranged in such a manner that all of them became molten after 540 mm through the transition region.

From the vent 12, the volatile components generated from the molten resin were evacuated and removed. Decompression degree is -720
mmHg. The used raw materials and other conditions were the same as in Example 1.

Example 2: Example of the present invention (1) (part 2) A three-thread screw (diameter: 44 mm, length: 144)
Except for using a 5 mm) co-rotating twin-screw extruder, the same configuration as in Example 1 was adopted (however, the length of each area was almost proportionally compressed) to produce thermoplastic resin pellets. did.

Comparative Example 2: The same configuration as in Comparative Example 1 was adopted except that a co-rotating twin-screw extruder having a three-thread screw (diameter: 44 mm, length: 1445 mm) was used (however, The length of each area was approximately proportionally compressed) to produce thermoplastic resin pellets.

Example 3: Example of the present invention (2) A co-rotating twin-screw extruder having the same screw / cylinder arrangement (arrangement) as in Comparative Example 1 was used. The supply of the extruded material was the same as in Comparative Example 1.

At this time, pellets having the same composition as the thermoplastic resin to be melted, kneaded and discharged using the deaeration port 12 were supplied at a rate of 1 kg / hour using a screw type feeder.

Example 4: Example (3) of the present invention (3) A co-rotating twin-screw extruder having the same screw / cylinder arrangement (arrangement) as in Example 2 was used. The supply of the extruded material was the same as in Example 2.

At this time, pellets having the same composition as the thermoplastic resin melted and kneaded and discharged from the sixth cylinder were supplied at a rate of 1 kg / h using a screw feeder.

Example 5: Example (3) of the present invention (3) Under the operating conditions of Example 4, the same composition as the thermoplastic resin which is melted, kneaded and discharged through the vent hole of the sixth cylinder. Was supplied at 5 kg / h using a screw feeder.

Example 6: Example (3) of the present invention (3) A co-rotating twin-screw extruder having the same screw / cylinder arrangement (arrangement) as in Example 2 was used.

At this time, pellets having the same composition as the thermoplastic resin to be melted and kneaded and discharged from the first supply port were supplied at a rate of 1 kg / hour using a screw type feeder. From the second supply port, a powdery polyamide-imide resin previously blended so as to have a titanium oxide content of 3% by weight was supplied at a rate of 25 kg / hour.

Table 1 summarizes the results of carbide measurement of the pellets produced in Examples 1 to 6 and Comparative Examples 1 and 2.

[0074]

[Table 1]

From Table 1, in Examples 1 to 6 of the present invention, pellets having a small amount of carbide were obtained. In particular, in Examples 4 to 6, an epoch-making effect was observed in suppressing carbides.

The volatile components of the pellets obtained in Examples 1 to 6 were not different from those of Comparative Examples 1 and 2 in which vacuum venting was performed. The tensile strength and elongation at break were equivalent.

On the other hand, a method of performing a vacuum vent (Comparative Examples 1 to 5)
In 2), the amount of carbide was large.

[0078]

According to the present invention, in producing thermoplastic resin pellets by kneading a thermoplastic resin or a thermoplastic resin and an additive in an extruder, twin-screw extrusion substantially not having a vacuum devolatilization region is provided. By performing the screw arrangement of the machine, the solid conveying area can be lengthened, and the carbide contained in the obtained thermoplastic resin pellets can be reduced.

Further, thermoplastic resin pellets having substantially the same composition as the thermoplastic resin pellets which are melted, kneaded and discharged are supplied from the supply port of the extruder, whereby:
The carbide contained in the obtained thermoplastic resin pellets can be significantly reduced.

[Brief description of the drawings]

FIG. 1 shows an example of a cylinder / screw arrangement of a twin-screw extruder according to the present invention.

FIG. 2 shows a cylinder / screw arrangement (arrangement) example of a conventional twin-screw extruder: used in Examples and Comparative Examples

[Explanation of symbols]

 1: Cylinder 2: Screw 3: Discharge mouthpiece 4: First supply port 5: Second supply port 6: Deaeration port 7: Compression area 8: Pressure reduction area 9: Transition area 10: Melting / kneading area 11: Molten resin Transport area 12: Deaeration port in area where resin melts 13-17: Transport area of melt

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 503: 06 B29K 503: 06 C08L 79:08 C08L 79:08 F term (Reference) 4F070 AA04 AA07 AA08 AA12 AA13 AA15 AA18 AA22 AA24 AA35 AA42 AA47 AA50 AA58 AC15 AC27 AC28 AC31 FB06 FC06 4F201 AA40 AB11 AC04 AP05 BA01 BA02 BC01 BC13 BC17 BC19 BC37 BK02 BK13 BK26 BK36 BK40 BK49 BL09 BL43 BN31

Claims (5)

[Claims] 1. A method for producing a thermoplastic resin pellet by melting and kneading a thermoplastic resin or a thermoplastic resin and an additive by using a twin-screw extruder and discharging the molten resin from a die. A method for producing a thermoplastic resin pellet, comprising the following regions A to C. A. In a twin-screw extruder, a thermoplastic resin glass including a compression area provided with a screw element serving as a compression / pressure increase area of a thermoplastic resin and a pressure reduction area provided with a screw element for reducing pressure following the compression area. A transport region preheated at a temperature lower than the transition temperature (Tg) or lower than the melting point (Tm) and at which the thermoplastic resin does not substantially melt. B. Transition region where the thermoplastic resin melts. C. A molten resin conveying region formed substantially in contact with the molten resin discharge mouthpiece in a region where there is substantially no vacuum devolatilization region and the free volume filling rate of the molten resin in the cylinder substantially approaches 100%. 2. A thermoplastic resin pellet which is melted and kneaded and discharged when a thermoplastic resin or a thermoplastic resin and an additive are melted and kneaded using a twin screw extruder. A thermoplastic resin pellet having substantially the same composition as the above is supplied from a supply port at a rate corresponding to 1/1000 to 1/2 of a molten resin discharge amount of an extruder. . 3. A thermoplastic resin pellet having substantially the same composition as thermoplastic resin pellets which are melted and kneaded and discharged is supplied from a supply port to a supply port of 1/1000 of a molten resin discharge amount of an extruder.
The method for producing thermoplastic resin pellets according to claim 1, wherein the thermoplastic resin pellets are supplied at a rate corresponding to １ ／. 4. The thermoplastic resin is in the form of a powder, and (A) the powder has an average particle diameter of 0.1 to 700 μm;
The method for producing thermoplastic resin pellets according to any one of claims 1 to 3, wherein the powder has a bulk density of 0.1 to 0.8 g / ml. 5. The thermoplastic resin is represented by the following general formula (I): (Wherein, R is a divalent aromatic residue and / or an aliphatic residue) a polyamideimide resin powder having a repeating unit represented by the following formula as a main structural unit:
A method for producing a thermoplastic resin pellet according to claim 1.