JP2003211443A - Method for manufacturing blister-resistant liquid crystal polyester composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a blister-resistant liquid crystal polyester composition, capable of obtaining a molded article not generating a surface blister under a high temperature environment in solder welding or the like at surface mounting. <P>SOLUTION: In a method for manufacturing the liquid crystal polyester composition with a load bending temperature of 230°C or higher by melting and kneading 90-40 wt.% of a liquid crystal polyester with a melting point of 320°C or higher, which is obtained by the polycondensation of a monomer group containing 80 mol % or more of p-hydroxybenzoic acid, terephthalic acid and 4,4'-hydroxydiphenyl (including derivatives of them), and 10-60 wt.% of an inorganic filler using a kneader having an opening for removing a volatile component from the material to be kneaded and a pair of two-start screws, a kneader of which the screw meshing ratio is 1.60 or more is used to manufacture the liquid crystal polyester composition excellent in blister resistance. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface swelling (blister) under a high temperature environment such as a solder welding process, which is used for electric / electronic parts corresponding to surface mounting technology (SMT) including a liquid crystal polyester-containing component. The present invention relates to a liquid crystal polyester composition containing an inorganic filler that does not cause the above.

[0002]

2. Description of the Related Art Liquid crystal polyester is excellent in moldability and heat resistance and is used as a constituent material for small electronic parts.
Among them, p-hydroxybenzoic acid, terephthalic acid,
When a liquid crystal polyester is produced by polycondensation using 4,4′-dihydroxybiphenyl as a main component, the melting point is 320 ° C.
When the above liquid crystalline polyester is obtained and the liquid crystalline polyester and the inorganic filler are appropriately melt-kneaded, a composition having a deflection temperature under load of 230 ° C. or higher can be obtained. Since the liquid crystal polyester composition has the highest level of heat resistance in the thermoplastic resin composition, it is exposed to high-temperature environments such as constituent materials for electric and electronic parts that require solder heat resistance, and other solder welding processes. It is preferably used for structural members.

However, the heat resistance required for the thermoplastic resin composition constituting the above-mentioned electric / electronic parts is not limited to the melting point and the deflection temperature under load, but also in the high temperature environment related to the solder welding process or the use environment. Therefore, it is required that the molded product does not cause surface blister (blister) (hereinafter, this property is referred to as "blister resistance").

That is, the electricity used in the solder welding process
When a liquid crystal polyester composition having poor blister resistance is contained as a constituent material in an electronic component, a device composed of these becomes an off-spec product in the final manufacturing process. In particular, in recent years, there has been a great demand for a resin composition having excellent blister resistance that can cope with the processing temperature when using lead-free solder.

The factors and causes that control the superiority and inferiority of the blister resistance are still unknown. In the chemical and physical constituent factors of the liquid crystal polyester composition, the polymerization reaction step of obtaining the liquid crystal polyester from the monomer, the melt-kneading step of obtaining the inorganic filler-containing composition, and the molding processing step (mainly the injection molding step) of obtaining a molded article. It is considered that mechanical and thermal history, interfacial properties between the liquid crystalline polyester and the inorganic filler inside the molded product, etc. are complicatedly related. That is, even if the heat resistance such as the melting point and the deflection temperature under load is excellent, the blister resistance is not necessarily excellent.

For example, in JP-A-5-125258, the mechanical and thermal history of a liquid crystal polyester composition subjected to a plasticizing step during injection molding is controlled by adding a specific higher fatty acid metal salt or the like to prevent blistering. A technique for obtaining a flexible molded body has been proposed.

[0007]

In view of such circumstances, the present invention is excellent in blister resistance while maintaining excellent moldability of liquid crystal polyester composition and basic heat resistance such as melting point and deflection temperature under load. An object of the present invention is to provide a liquid crystal polyester composition, and to improve stability in a solder welding process of electric / electronic parts and the like having the material as a constituent and reliability of a structural member exposed to a high heat environment.

[0008]

[Means for Solving the Problems] As a result of various studies on the relationship between “blister resistance” and “melt-kneading process of liquid crystal polyester and inorganic filler”, the present inventors have found that hydroxybenzoic acid and terephthalic acid. , 4,4'-dihydroxybiphenyl (including these derivatives) 80 mol%
90-40% by weight of a liquid crystalline polyester having a melting point of 320 ° C. or higher obtained by polycondensing a monomer group containing the above and an inorganic filler 10-
In a method for producing a liquid crystal polyester composition having a deflection temperature under load of 250 ° C. or higher, obtained by melt-kneading 60 wt% of a material to be kneaded with an kneader having an opening for removing volatile components and a pair of two-thread screws. The present invention has been completed by finding that the screw mesh ratio is extremely closely related to the blister resistance, and setting the screw mesh ratio to 1.60 or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The liquid crystalline polyester according to the present invention contains p-hydroxybenzoic acid, terephthalic acid, and 4,4′-dihydroxybiphenyl (including derivatives thereof; the same applies hereinafter).
Melting point 32 obtained by polycondensing a monomer group containing 0 mol% or more
It is 0 ° C or higher. A melting point of 320 ° C or higher means DS
In C or TMA analysis, it means that a peak is detected in a region of 320 ° C or higher, and a separate peak may be detected at 320 ° C or lower. The requirement for the melting point is, for example, that hydroxybenzoic acid is added to the monomer for polycondensation to 5
0 mol% or more, or 20 mol% or less of a monomer relating to polycondensation other than p-hydroxybenzoic acid, terephthalic acid, and 4,4′-dihydroxybiphenyl,
It can be achieved by a known method such as preferably 10 mol% or less.

By satisfying the above combination conditions,
The main chain of the liquid crystal polyester is mainly aromatic ring,
In addition to basic heat resistance, good moldability is secured (shear heat generation in the molten state is suppressed), and basic characteristics for blister resistance are secured. As long as this heat resistance and moldability are ensured, the remaining 10 mol% is not limited to a monomer, but isophthalic acid, 2,6-hydroxynaphthenic acid, a monomer having an aromatic ring such as hydroquinone is used, A wholly aromatic liquid crystal polyester structure is preferable, but the structure is not particularly limited.

Preferably, p-hydroxybenzoic acid 40
~ 80 mol%, terephthalic acid 10-40 mol%, 4,
4'-dihydroxybiphenyl is 10 to 40 mol% (the total of the three is 100 mol%), and if necessary, a predetermined mol% is substituted with the aromatic monomer.

The inorganic filler is not particularly limited, and known ones can be used, and the deflection temperature under load due to these filling effects is 230.
C is obtained. For example, molybdenum disulfide, talc, mica, glass flakes, clay, sericite, calcium carbonate, calcium silicate, silica, alumina, aluminum hydroxide, calcium hydroxide, graphite, amorphous carbon, potassium titanate, glass. Fiber, carbon fiber, various whiskers and the like can be mentioned. These may be used alone or in combination of two or more. Among these inorganic fillers, talc, mica, milled glass, and glass fiber are preferable because they have an excellent balance of moldability, heat resistance, and blister resistance.

In the present invention, liquid crystal polyester 90-40
wt% and inorganic filler 10 to 60 wt% (total of 10
0 wt% ) Is melt-kneaded. 10wt% inorganic filler
% Or less, the anisotropy becomes high and the surface appearance of the molded product deteriorates, and when it exceeds 60 wt%, the moldability and blister resistance deteriorate.

In the present invention, as the melt-kneading means, a kneader having a pair of double-threaded screws and an open port (vent port) is used. For example, a twin-screw kneading extruder having a vent port. The rotation direction of the pair of screws is preferably the same direction because the materials to be kneaded are switched (the surface is renewed) sufficiently. The opening is for removing volatile matter, which is one of the causes of deterioration of blister resistance, from the material to be kneaded, and may be opened to the atmosphere or connected to a vacuum pump to reduce the pressure. In addition, a plurality of openings may be provided.

The pair of screws have at least one kneading disc portion. The kneading disc part is composed of one or a plurality of kneading discs. The screw and the kneading disc have an elliptical shape or an elliptical shape in cross section perpendicular to the screw axis, and a pair of the screw and the kneading disk are meshed with each other.

In such a structure, the gap between the tip portion of the kneading disk and the inner surface of the barrel is, for example, 0.5.
Since the width is extremely narrow, the shearing force is large and the melt-kneading is effectively performed. However, local heat is generated in the tip portion. The present inventors considered that optimizing the balance between obtaining uniform melt-kneading and avoiding excessive shear stress history has a great influence on the improvement of blister resistance. Further, the kneading disk portion plays an important role in kneading, but if it is provided excessively, a large shear heat insulation occurs in the entire material to be kneaded, which causes deterioration of the polymer. To keep the material temperature below a certain level to avoid this, the screw rotation speed cannot be increased,
I thought that there was a problem that productivity was limited. The present invention is based on such a detailed analysis of the kneading state.

In the present invention, the value obtained by dividing the major axis length of the cross-sectional shape of the screw and the kneading disk by the minor axis length (hereinafter referred to as "meshing ratio") is 1.60 or more, preferably 1. It should be 62 or more. The mesh ratio of a kneading machine having a pair of general-purpose screws is 1.55 or less. As a kneading machine according to the present invention having a meshing ratio of 1.62, which is available from the market, there is HYPERKTX series manufactured by Kobe Steel, Ltd.

Due to the screw mesh ratio, the material to be kneaded is more uniformly subjected to shear stress in a state where slippage and the like are suppressed, and shear heat generation is more uniformly generated. Among the liquid crystal polyesters, a polymer having a melting point of more than 320 ° C. and an aromatic monomer as a main repeating unit, such as the liquid crystal polyester according to the present invention, is difficult to melt only by preheating from a barrel heater. The stress is evenly received, shearing heat is uniformly generated in the material to be kneaded to avoid melting only the polymer surface, and melting the entire polymer suppresses local deterioration, which deteriorates the blister resistance. It is thought to suppress. In the present invention, by setting the “mesh ratio” to 1.60 or more, preferably 1.62 or more, the ratio of the heat energy for melting the liquid crystal polyester depending on the shear heat generation increases, and uniform shear heat generation occurs. Reserved. Further, due to the meshing ratio, a larger void portion is generated between the screw and the barrel, so that the material to be kneaded is opened into a sufficient void immediately after being subjected to shearing heat and is air-cooled, which causes blisters at the same time. It is considered possible to discharge volatile components with high possibility.

In order to further exert the effect of the present invention, at least one kneading disc portion composed of one or a plurality of kneading discs is provided on each of the upstream side and the downstream side of the opening of the pair of screws, and It is preferable that the length of each of the kneading disc portions is 3 times or less of the barrel inner diameter, and the total length of the kneading disc portions is 8 times or less of the barrel inner diameter.

By providing at least one kneading disk portion on each of the upstream side and the downstream side of the opening in the pair of screws, it is possible to secure the discharge of the volatile components in the material to be kneaded.

By setting the length of the kneading disk portion at one location to 3 times or less of the barrel inner diameter,
It is possible to avoid excessive continuous shear heat generation in the material to be kneaded. If it is more than 3 times, the blister resistance is deteriorated, which is not preferable.

If the total length of the kneading discs provided at one or more places in the screw is 8 times or less of the barrel inner diameter, excessive kneading history of shearing occurs in the material to be kneaded. Can be avoided. 8
If it is more than twice, the blister resistance is deteriorated, which is not preferable.

When the above conditions are secured, reliable and uniform kneading and local occurrence of shear heat insulation and excessive accumulation of the material to be kneaded can be avoided, and the degree of freedom of the screw rotation speed is ensured. A sufficient discharge amount of the material can be obtained.

The structure of the kneading disk section is as follows.
(1) A plurality of kneading discs having a rightward twist of θ °, (2) a kneading disc having a leftward twist of θ °, and (3) a single kneading disc. The value of θ is, for example, 1
There are 5 °, 30 ° and 45 °.

In the present invention, the water content of the liquid crystal polyester charged into the hopper of the kneading machine is 500 pp.
It is preferable that m is less than or equal to m to suppress the influence of water intervening at the time of shear heat generation. If the water content is more than 500 ppm, the liquid crystal polyester may be decomposed in the melting step to deteriorate the blister resistance. The water content level is, for example, by allowing the liquid crystal polyester to stand in a dry heat oven set at 150 ° C. for 1 hour or more, or
It can be obtained by drying the liquid crystal polyester for 1 hour or more with a hopper dryer set at 150 ° C. However, if it is possible to maintain 500 ppm or less, the drying step is not always necessary.

In the present invention, 50 wt% or more of the liquid crystal polyester charged into the hopper of the kneading machine is used as a powder to reduce the pellet content, and a slip phenomenon occurs when only the pellet surface is melted when shear heat is generated. It is preferable to suppress the shear fracture of the pellet. These may hinder the uniform melt-kneading of the material to be kneaded, and the blister resistance may deteriorate. The particle size level of the powdery liquid crystalline polyester is sufficient to suppress the occurrence of the above phenomenon, and is sufficient if the pellets are crushed, but it is preferably 20 mesh passing level.

The filler is preferably side-fed from one or more points of the kneader. A fibrous filler such as glass fiber or carbon fiber is preferably added in a state where the polymer is sufficiently plasticized in order to avoid cutting of the fiber.

In the present invention, in addition to inorganic fillers, organic fillers, various conventionally known stabilizers, antioxidants, ultraviolet absorbers, pigments, dyes and modifiers are used in order to improve physical properties in practical use. Etc. may be added. In particular, a phosphite ester having excellent thermal stability represented by the following formula (1) is particularly preferably one or two or more having a melting point of 230 ° C. or higher in consideration of the deflection temperature under load of the resin composition. Addition of 0.01 to 1 part by weight is effective as a measure against oxidative deterioration due to shear heat generation of thermal energy for melting the liquid crystal polyester.

[Chemical 2] As a specific compound, cyclic neopentatriylbis (2,4-di-tert-butylphenyl) phosphite (Adeka Stab PEP-24G from the market,
Melting point 170 ° C .: available from Asahi Denka Co., Ltd. ) And cyclic neopentatriylbis (2,6-di-t
ert-butylphenyl) phosphite (Adeka Stab PEP-36 from the market, melting point 237 ° C .: Asahi Denka Co., Ltd.)
Made available. ) Is preferred.

[0029]

According to the method of the present invention, when the liquid crystal polyester and the inorganic filler are kneaded, a biaxial kneader having a screw mesh ratio of 1.6 or more is used, so that the liquid crystal polyester excellent in blister property is obtained. A composition is obtained.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. <Synthesis of Liquid Crystal Polyester> Synthesis of liquid crystal polyester was performed as follows. Synthesis of Liquid Crystal Polyester A: Made of SUS316,
1105.0 g (8.0%) of p-hydroxybenzoic acid was added to a 6 L polymerization tank (manufactured by Nitto High Pressure Co., Ltd.) having a double helical stirring blade.
0 mol), terephthalic acid 744.8 g (4.00 mo)
l), 4,4'-dihydroxybiphenyl 664.5 g
(4.00 mol) was charged, and decompression of the polymerization tank-nitrogen injection was performed twice to perform nitrogen substitution, and then acetic anhydride 173 was used.
1.4 g (16.96 mol) was added, the temperature was raised to 150 ° C. in 1 hour at a rotation speed of the stirring blade of 100 rpm, and the acetylation reaction was performed for 2 hours under reflux. After the acetylation was completed, the acetic acid was distilled off and the temperature was raised at 0.5 ° C./min.
At 0 ° C., the polymer was taken out from the outlet at the bottom of the polymerization tank. The polymer taken out was pulverized with a pulverizer to 20 mesh or less. Next, solid phase polymerization was carried out by a heating device (manufactured by Asahi Shoko Co., Ltd.) having a cylindrical rotary reactor. The crushed polymer was charged into a cylindrical rotary reactor, nitrogen was circulated at 1 liter / min, and the rotation speed was 20 rpm.
After heating to 280 ° C over 2 hours and holding at 280 ° C for 3 hours, heating up to 300 ° C in 30 minutes and holding for 3 hours, heating to 320 ° C in 30 minutes and holding for 3 hours After further heating up to 340 ° C. in 30 minutes and holding for 2 hours,
The polymer was obtained by cooling to room temperature for 1 hour. When the melting point of the obtained polymer was measured by DSC, the melting point was 410 ° C. The apparent viscosity at 440 ° C is 2500.
It was a poise.

Synthesis of Liquid Crystal Polyester B: SUS316
In a 6 L polymerization tank (manufactured by Nitto High Pressure Co., Ltd.) having a double helical stirring blade as a material and p-hydroxybenzoic acid 1330.
1 g (9.63 mol), isophthalic acid 133.4 g
(0.803 mol), terephthalic acid 400.0 g
(2.408 mol) and 4,4'-dihydroxybiphenyl (597.7 g, 3.21 mol) were charged, and decompression-nitrogen injection was performed twice in the polymerization tank to replace the nitrogen, and then 1736.9 g (17 0.01 mol) was added, the temperature was raised to 150 ° C. in 1 hour at a rotation speed of a stirring blade of 100 rpm, and the acetylation reaction was performed for 2 hours under reflux. After completion of acetylation, the acetic acid was distilled off at 0.5 ° C /
The temperature was raised in minutes, and at 320 ° C., the polymer was taken out from the outlet at the bottom of the polymerization tank. The polymer taken out was pulverized with a pulverizer to 20 mesh or less. Then, solid phase polymerization was carried out by a heating device (manufactured by Asahi Shoko Co., Ltd.) having a cylindrical rotary reactor. The crushed polymer was charged into a cylindrical rotary reactor, nitrogen was circulated at 1 liter / min, and the temperature was raised to 290 ° C. at a rotation speed of 20 rpm over 2 hours to 2
After holding at 90 ° C. for 6 hours, it was cooled to room temperature in 1 hour to obtain a polymer. When the melting point of the obtained polymer was measured by DSC, the melting point was 358 ° C. The apparent viscosity at 370 ° C. was 910 poise.

[0032] Material to be kneaded I: (1) Liquid crystal polyester: Liquid crystal polyester A 60 wt% (2) Inorganic filler: crushed glass fiber Product name “MF-20JMH1-20” (Asahi Phi 40% by weight

[0033] Material to be kneaded II: (1) Liquid crystal polyester: Liquid crystal polyester B 60 wt% (2) Inorganic filler: crushed glass fiber Product name “MF-20JMH1-20” (Asahi FA 20 wt% Glass fiber product name “PX-1” (Made by Asahi Fiber Glass Co., Ltd.)                                                   20 wt%

[0034] Material to be kneaded III: (1) Liquid crystal polyester: Liquid crystal polyester B 60 wt% (2) Inorganic filler: crushed glass fiber Product name “MF-20JMH1-20” (Asahi Phi Made by Bargrass) 20 wt% Glass fiber product name “PX-1” (Made by Asahi Fiber Glass Co., Ltd.)                                                   20 wt% (3) Antioxidant: cyclic neopentatriylbis (2,6-di-ter t-Butylphenyl) phosphite (ADK STAB PEP-36: Asahi Denka Co., Ltd.) Made) 0.1 parts by weight

In the above materials to be kneaded I to III, liquid crystal polyester pellets and powders having different ratios and water contents were used. Water content is measured according to JIS-K510
In accordance with No. 1, it was carried out by the heating weight loss method. Nominal size 50
Remove the lid of the × 30 mm flat scale bottle and dry for 2 hours in a dryer kept at 105 ° C. After the drying is completed, cool the scale bottle to a room temperature in a desiccator, cover the scale bottle and weigh it. It was measured to the order of 1 mg. 20 g of a sample was weighed to the order of 1 mg in this balance bottle, the lid was put on, and the mass was measured again. Remove the lid of the weighing bottle and put the weighing bottle containing the sample in 10
After drying for 2 hours with a dryer kept at 5 ° C., after the completion of drying, the weighing bottle was allowed to cool to room temperature in a desiccator, the weighing bottle was capped, and the mass was measured to the order of 1 mg. Then, the weight loss on heating was calculated from the mass before and after heating.

The two types of kneaders used and the processing conditions for the materials to be kneaded were as follows. <Melt Kneader A> Used in Examples 1 to 12. Screw mesh ratio: 1.62 Barrel size: Inner diameter 46 mm, L / D = 36 Temperature condition for material to be kneaded: Barrel temperature: C1: 380 ° C, C2: 410 ° C, C3:
410 ° C, C4: 410 ° C, C5: 410 ° C, C6: 4
10 ° C, C7: 390 ° C, C8: 370 ° C, C9: 37
0 ° C. Head temperature: 410 ° C. Die temperature: 410 ° C. Temperature conditions for materials to be kneaded II and III: Barrel temperature: C1: 300 ° C, C2: 320 ° C, C3:
350 ° C, C4: 370 ° C, C5: 370 ° C, C6: 3
70 ° C, C7: 350 ° C, C8: 330 ° C, C9: 33
0 ° C. Head temperature: 350 ° C. Die temperature: 350 ° C. Screw rotation speed: 300 rpm

<Melt Kneader B> Used in Comparative Examples 1-6. Screw mesh ratio: 1.55 Barrel size: Inner diameter 46 mm, L / D = 36 Temperature condition for material to be kneaded: Barrel temperature: C1: 380 ° C, C2: 410 ° C, C3:
410 ° C, C4: 410 ° C, C5: 410 ° C, C6: 4
10 ° C, C7: 390 ° C, C8: 370 ° C, C9: 37
0 ° C. Head temperature: 410 ° C., Die temperature: 410 ° C. Temperature conditions for materials to be kneaded II and III: Barrel temperature: C1: 300 ° C, C2: 320 ° C, C3:
350 ° C, C4: 370 ° C, C5: 370 ° C, C6: 3
70 ° C, C7: 350 ° C, C8: 330 ° C, C9: 33
0 ° C. Head temperature: 350 ° C. Die temperature: 350 ° C. Screw rotation speed: 300 rpm

The screw structures of the kneading machine A and the kneading machine B are a pair of co-rotating screws, and the length of the kneading disc is less than 3 times the inner diameter of the barrel and the total length is the barrel. It was 8 times or less the inner diameter, and was substantially the same except for the meshing ratio.

<Production of Liquid Crystal Polyester Composition> Materials I to III to be kneaded are melt-kneaded by melt-kneading machines A and B, respectively, and extruded from a die to obtain strands, which are cut by a pelletizer to form pellets of liquid crystal polyester composition. Got

<Manufacture of test piece for measuring deflection temperature under load and blister resistance> The liquid crystal polyester composition pellets obtained as described above are put into a hopper of an injection molding machine,
Injection molding was performed under the following conditions. The shape of the test piece for deflection temperature under load was in accordance with ASTM648, and the test piece for blister resistance measurement was ASTM L8222 type L. Injection molding machine: Sumitomo Heavy Industries, Ltd .: SG-25 Mold clamping pressure: 25 tons Molding condition of material I to be kneaded: Barrel temperature: C1: 370 ° C, C2: 400 ° C, C3:
410 ° C. Nozzle temperature: 410 ° C., mold temperature: 150 ° C. Injection speed: 100 mm / sec Molding conditions of materials II and III to be kneaded: Barrel temperature: C1: 310 ° C., C2: 340 ° C., C3:
350 ° C Nozzle temperature: 350 ° C, Mold temperature: 80 ° C Injection speed: 100 mm / sec

(Measurement of deflection temperature under load and blister resistance) Deflection temperature under load: According to ASTM648. 25
Since the displacement was below the specified value at 0 ° C, both were 250
After confirming that the temperature was not lower than 0 ° C, the measurement was terminated at that time. Blister resistance: The test piece was allowed to stand in a dry heat oven set at a temperature of 5 ° C. for 30 minutes, and the maximum temperature at which blisters did not occur was used as a blister resistance index.

The results are shown in Tables 1-3.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

As shown in Tables 1, 2, and 3, the liquid crystal polyester resin composition (Example) produced according to the present invention was
The blister resistance was superior to that of the comparative example.

Continued front page    (72) Inventor Toshio Inoue             3-6-4-512 Takatsu Ward, Kawasaki City, Kanagawa Prefecture F-term (reference) 4F201 AA24J AB11 AB16 AC04                       BC37 BD05 BK13 BK27 BK36                       BK41 BK42                 4J029 AA05 AB04 AD06 AD10 AE01                       BB10A CB06A EB05A JA283                       JC643 LA09

Claims (4)

[Claims] 1. A liquid crystal polyester having a melting point of 320 ° C. or higher, which is obtained by polycondensing a monomer group containing 80 mol% or more of p-hydroxybenzoic acid, terephthalic acid and 4,4′-dihydroxybiphenyl (including their derivatives). 90-4
Deflection temperature under load 2 obtained by melting and kneading 0 wt% and 10 to 60 wt% of inorganic filler with a kneader having an opening for removing volatile components from a material to be kneaded and a pair of two-row screws.
A method for producing a blister-resistant liquid crystal polyester composition, wherein the screw mesh ratio of the kneader is 1.60 or more in the method for producing a liquid crystal polyester composition at 30 ° C. or higher. 2. The method for producing a blister-resistant liquid crystal polyester composition according to claim 1, wherein the water content of the liquid crystal polyester charged into the hopper of the kneading machine is 500 ppm or less. 3. The method for producing a blister-resistant liquid crystal polyester composition according to claim 1, wherein 50 wt% or more of the liquid crystal polyester charged into the hopper of the kneader is a powder. . 4. The method according to claim 1, wherein 0.01 to 1 part by weight of one or more phosphite represented by the following formula (1) is added. Method for producing a blister-resistant liquid crystal polyester composition. [Chemical 1]