JPH0465455A - Liquid crystal polyester composition - Google Patents

Abstract

PURPOSE:To obtain a composition, excellent in heat resistance, moldability, fluidity and mechanical properties, further good in friction and sliding characteristics and suitable as sliding parts, etc., by blending a specific liquid crystal polyester with powdery silicone in a specified amount. CONSTITUTION:A liquid crystal polyester composition is obtained by blending (A) 100 pts. wt. liquid crystal polyester, composed of structural units expressed by formulas I to IV (X is formulas V, VI, etc.; Y is formulas V, VII, etc.), having 190-280 deg.C deflection temperature under load, <=330 deg.C liquid crystal starting temperature and <=10000 P melt viscosity and capable of forming an anisotropic melt phase with (B)0.5-20 pts. wt., preferably 1-10 pts. wt. powdery silicone. Furthermore, 100 pts. wt. aforementioned composition, as necessary, is blended with (C) <=200 pts. wt. inorganic filler (e.g. glass fiber or carbon fiber).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a liquid crystal polyester resin composition that has excellent heat resistance, moldability, fluidity, and mechanical properties, particularly excellent friction and sliding properties. It is.

[Conventional technology]

In recent years, there has been an increasing demand for higher performance plastics, and a large number of polymers with various new properties have been developed and put on the market. Among them, polymers with optical anisotropy, which is characterized by parallel arrangement of molecular chains, are particularly popular. Liquid crystal polymers have attracted attention because of their excellent mechanical properties.

Examples of polymers that form an anisotropic melt phase include liquid crystal polymers obtained by copolymerizing polyethylene terephthalate with P-hydroxybenzoic acid (Japanese Patent Application Laid-open No. 72393/1983);
Liquid crystal polymer copolymerized with P-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid
Also known are liquid crystal polymers prepared by copolymerizing p-hydroxybenzoic acid with 4,4'-dihydroxybiphenyl, terephthalic acid, and isophthalic acid (Japanese Patent Publication No. 57-24407).

[Problem to be solved by the invention]

However, the liquid crystal polymers known so far have a low heat distortion temperature of less than 190°C, resulting in insufficient heat resistance, while others have a heat distortion temperature of 190°C or higher, which is good heat resistance. , the liquid crystal start temperature is too high, 400℃
It has been difficult to obtain a liquid crystal polymer that has a good balance between heat resistance, moldability, and fluidity, such as high melt viscosity and high melt viscosity.

In addition, it was found that liquid crystal polyester has a large coefficient of dynamic friction because its molecular chains are easily oriented to form fibrils, and therefore its wear resistance is not sufficient. If silicone oil or the like is added to improve the sliding friction characteristics, it is possible to lower the coefficient of dynamic friction, but a new problem arises in that the silicone oil oozes out onto the surface of the molded product. It was found that this occurs.

Therefore, the present invention solves the above-mentioned problems, has excellent heat resistance, moldability, fluidity, and mechanical properties, and is particularly suitable for sliding ml.
! The object of the present invention is to obtain a liquid crystal polyester resin composition with improved properties and excellent wear resistance.

[Means to solve the problem]

In order to achieve the above-mentioned problem, the present inventors conducted intensive studies and found that the use of powdered silicone dramatically improves the abrasion resistance of liquid crystal polyester resin, and thus arrived at the present invention. did.

That is, the present invention is composed of the following structural units (I) to (IV), and forms an anisotropic melt phase having a deflection temperature under load of 190 to 280°C, a liquid crystal start temperature of 330°C or less, and a melt viscosity of 10,000 voids or less. The present invention provides a liquid crystal polyester resin composition having excellent abrasion resistance, which contains 0.5 to 20 parts by weight of powdered silicone (B) per 100 parts by weight of liquid crystal polyester (A).

+0-X-0÷ ...... (III) +0C-Y-CO-)- ...... (IV) represents one or more groups) of the liquid crystal polyester (A) in the present invention The structural unit (1) represents a structural unit of polyester produced from P-hydroxybenzoic acid, and the structural unit (II) represents 4,
It shows a structural unit generated from 4'-dihydroxybiphenyl, and the structural unit (I[[) is hydroquinone, t-
Butylhydroquinone, phenylhydroquinone, 2,
A structural unit formed from one or more dihydroxy compounds selected from 6-hydroxynaphthalene, ethylene glycol, and 4,4'-dihydroxydiphenyl ether.

Furthermore, the structural unit (IV) is one or more aromatic groups selected from terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,41-diphenyldicarboxylic acid, and 4,4''-diphenyl etherdicarboxylic acid. Shows a structural unit generated from dicarboxylic acid.

Among them, X of the structural unit (I[[) is the unit (
The Y of TV) is preferably 1-.

Therefore, when using groups other than these, it is preferable to use them as small amounts of copolymerization components.

The copolymerization ratio of structural units (1), (II), and (If) (structural unit (IV) is substantially equimolar to [(If) + (I [[)]]) is arbitrary, but the fluidity From this point of view, the following copolymerization amount is preferable. That is, when the structural unit cap) is -CHzCHx-, the structural unit [(II)+(
III)] is the structural unit [(1)+(II)+(nl)]
is preferably 77 to 95 mol%, and more preferably 80 to 93 mol%, and the structural unit (I[[) is [(I)+(II)+
(III)] is preferably 23 to 5 mol%, and more preferably 20 to 7 mol%. Further, the molar ratio of structural units (1)/(n) is preferably 75/25 to 9515, and 78/22 to
93/7 is more preferred.

If the structural unit (I[[) is other than -CLCI (!- group,
Structural unit (1) is [(1)+('II)+(I[[)]
The amount is preferably 440 to 90 mol, particularly 60 to 90 mol.
Preferably it is 78 mol%. Further, the molar ratio of the structural units (n)/(III) is preferably 9/1 to 1/9, more preferably 7.5/2.5 to 2.5/7.5.
, 5/2.5 to 4/6 are particularly preferred.

The liquid crystal polyester (A) used in the present invention has a deflection temperature under load (synonymous with heat distortion temperature) of 190 to 280°C when no filler is blended.

If the deflection temperature under load is less than 190°C, the heat resistance is insufficient, and if it exceeds 280°C, the problem arises that the molding temperature of the resulting resin composition becomes high.

Here, the deflection temperature under load is based on ASTM D64B,
This value was measured using a 1/8" thick test piece at a stress of 18.6 kg/ciil.

In addition, the liquid crystal starting temperature of the liquid crystal polyester (A) is 33
It is essential that the temperature is 0° C. or lower, and preferably 260 to 330″C from the viewpoint of fluidity and heat resistance.

If the liquid crystal start temperature exceeds 330''C, it will be necessary to increase the molding temperature, which is not practical from the viewpoint of moldability.

In addition, it is essential that the melt viscosity is 10,000 poise or less, preferably 5.000 poise or less, especially 2.
．． 000 poise or less is more preferable.

Note that this melt viscosity is a value measured using a Koka type flow tester under conditions of (liquid crystal start temperature + 40° C.) and a slip rate of 1.000 (1/sec).

The method for producing liquid crystal polyester (A) in the present invention is as follows:
There are no particular restrictions, and it can be produced according to known polyester polycondensation methods.

For example, in the structural unit (I[[), -X- is CH2
If Cl, other than -, the following manufacturing methods (1) and (2) are used, -X- is -C)1. In the case of cH2-, the production method (3) is preferred.

(1) Polycondensation reaction of acetic acid removal from diacylated aromatic dihydroxy compounds such as p-acetoxybenzoic acid, 4,4゛-diacetoxybiphenyl, and 4,4゛-diacetoxybenzene and aromatic dicarboxylic acids such as terephthalic acid. method of manufacturing.

(2) After reacting an aromatic dihydroxy compound such as P-hydroxybenzoic acid, 4,4゛-dihydroxybiphenyl, or hydroquinone, or an aromatic dicarboxylic acid such as terephthalic acid with acetic anhydride to acylate the phenolic hydroxyl group, A method of manufacturing by removing acetic acid and polycondensation reaction.

(3) A method of producing by method (1) or (2) in the presence of one or more selected from polyethylene terephthalate, polymers, oligomers, and bis(β-hydroxyethyl) terephthalate.

Since liquid crystal polyester (A) with a high degree of polymerization is obtained, (
It is more preferable to use method 2) or (3).

Typical catalysts used in polycondensation reactions include metal compounds such as stannous acetate, tetrabutyl titanate, potassium acetate, antimony trioxide, magnesium, sodium acetate, and zinc acetate. It is effective for

The liquid crystalline polyester (A) of the present invention can be measured for its intrinsic viscosity in pentafluorophenol, and in this case, the intrinsic viscosity is 0.5a as measured at 60°C at a concentration of 0.1g/d1. /g or more is preferable, especially 1.0 to 15
．． 0d1/g is preferable, and when X in structural unit (III) contains -CHIC11,-, 1.0 to 3.0 is particularly preferable.

In addition, when polycondensing the liquid crystal polyester (A) used in the present invention, in addition to the components constituting the above (I) to (IV), 3.3'-diphenyldicarboxylic acid and 3.4'-diphenyldicarboxylic acid are added. , 2,2′-diphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4′-dicarboxylic acid, 1,2-bis(2-chlorophenoxy)ethane-4,4′-dicarboxylic acid, etc. Aromatic dicarboxylic acids, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, resorcinol, chlorohydroquinone, methylhydroquinone, aromatic dihydroxy compounds such as 2,7-hydroxynaphthalene, m-oxybenzoic acid, 2,6-
Aromatic oxycarboxylic acids such as oxynaphthoic acid and p-aminophenol, p-aminobenzoic acid, and
Aromatic imide compounds that have an imide bond and can form polyesters, ethylene oxide adducts of bisphenol A, and monomers made by adding ethylene oxide to the above-mentioned compounds that have a phenolic OH group such as β-hydroxyethoxybenzoic acid. Further copolymerization may be carried out within a small proportion that does not impair the purpose of the present invention.

On the other hand, the powdered silicone (B), which is another essential component of the composition of the present invention, includes powdered silicone resin, ultrafine silicone elastomer, and silicone oil on an inorganic support such as silica. A preferred example is one in which silicone oil is supported at a high concentration on an inorganic support, and a type in which a silicone oil is supported at a high concentration on an inorganic support is particularly preferable.

Examples of the silicone oil supported on the inorganic support include dimethyl silicone oil, methylphenyl silicone oil, polyether-modified silicone oil, silicone gum, etc.
Cs or more is preferable, and 3000 cs or more is more preferable.

In the composition of the present invention, the amount of powdered silicone blended is 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of liquid crystal polyester.

If it is less than 0.5 parts by weight, the effect of improving sliding properties will not be significant, and if it exceeds 20 parts by weight, heat resistance and mechanical properties will be impaired, so both are not preferred.

Furthermore, in the composition of the present invention, it is preferable to use an inorganic filler in combination, and fillers include glass fiber, carbon fiber, aromatic polyamide fiber, potassium titanate fiber, gypsum fiber, brass fiber, stainless steel fiber, steel fiber,
Examples include fibrous, powder, granular, or plate-like inorganic fillers such as ceramic fibers, boron whisker fibers, mica, talc, silica, calcium carbonate, glass beads, glass flakes, glass microballoons, clayey lastenite, and titanium oxide. .

Among the above fillers, glass fibers and carbon fibers are preferably used, and these may be used in combination. The types of glass fibers and carbon fibers are not particularly limited as long as they are generally used for reinforcing resins, and can be selected from, for example, long fiber types, single fiber types, chopped strands, middle fibers, and the like. Furthermore, the glass fibers may be coated or bundled with a thermoplastic resin such as ethylene/vinyl acetate copolymer, a thermosetting resin such as an epoxy resin, or a urethane resin, or a coupling material such as a silane or titanate resin. may be treated with a surface treatment agent or other surface treatment agent.

When adding an inorganic filler, the amount added is preferably 200 parts by weight or less based on the total of 100 parts by weight of the liquid crystal polyester (A) and the powdered silicone (B).

Furthermore, the composition of the present invention may contain antioxidants, heat stabilizers (for example, hindered phenol, hydroquinone, phosphites, and substituted products thereof), ultraviolet absorbers, etc., to the extent that the objects of the present invention are not impaired. agents (such as resorcinol, salicylates, benzotriazoles, benzophenones, etc.), lubricants and mold release agents (such as montanic acid and its salts, its esters, its half esters, stearyl alcohol, stearamide and polyethylene waxes), dyes (such as nitrosine) and Conventional additives such as colorants, including pigments (e.g. cadmium sulfide, phthalocyanines, carbon black, etc.), plasticizers, antistatic agents, and other thermoplastics can be added to impart desired properties.

The resin composition of the present invention is preferably melt-kneaded, and known methods can be used for melt-kneading. For example, the composition can be prepared by melt-kneading at a temperature of 200 to 350° C. using a Banbury mixer, a rubber roll machine, a kneader 1 single-screw or twin-screw extruder, or the like.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Reference Example In a reaction vessel equipped with a distillation tube and a stirring blade, 994.5 g (7.2 mol) of P-hydroxybenzoic acid (I) and 125.7 g (0.
675 mol), terephthalic acid 112.1 g (0,67
5 mol), 216.2 g (1,125 mol) of polyethylene terephthalate (I[) having an intrinsic viscosity of about 0.6 and 960.2 g (9.4 mol) of acetic anhydride,
Acetic acid depolymerization was performed under the following conditions.

First, the reaction was carried out for 4 hours at 130 to 150"C under a nitrogen atmosphere. Then, the temperature was raised to 250"C over 2.5 hours.
The reaction was further continued at 250°C for 2.5 hours. Furthermore, 2
After raising the system temperature to 320°C over time, 1.
The pressure inside the system was reduced to 0.3 mmHg in 5 hours, and the pressure was further reduced to 30 mmHg.
After continuing the reaction for several minutes, the polycondensation was completed. As a result of the above reaction, a beige colored polymer was obtained.

The theoretical structural formula of this polymer is as follows.

(Margin below this page) +0-@-CO+T/ -f-OCHzCHzO→i/ 1/+/n10=80/7.5/12.5/20 Also,
This polyester was placed on the sample stage of a polarizing microscope and the optical anisotropy was confirmed by raising the temperature.As a result, the liquid crystal start temperature was 29
The temperature was 4° C., and good optical anisotropy was exhibited.

The melting point of this polymer was measured using a PerkinElmer Model DSC-7 at a heating rate of 20°C/min, and the peak temperature was 316°C.

The logarithmic viscosity of this polymer was 1.70 d1/g, and the melt viscosity was 700 voids at 334°C and a shear rate of 1000 (1/sec), indicating extremely good fluidity.

Example 1 100 parts by weight of the liquid crystalline polyester of the reference example, powdered silicone (“Trefil” F-20 manufactured by Toshi/Dow Corning)
2) 1.5 parts by weight and 45 parts by weight of glass fiber (chopped strand 3III length) were melt-kneaded and pelletized using a 30aφ twin-screw extruder at a cylinder temperature of 280 to 320°C.

This polymer is inhabited by Nestal injection molding machine/Promatsu) 4
0/25 (manufactured by Sumitomo Heavy Industries Co., Ltd.), 30X30X3 under the conditions of cylinder temperature 320℃ 1 mold temperature 90℃
A wear test piece of m was molded. Using a lead powder type thrust type testing machine, the above test piece was subjected to a friction and wear test according to JIS K721.
It was carried out according to method B(A). Test load P = 10kgf
101! As a result of measurement under the conditions of test speed V = 20 m/min, the specific wear amount of the test piece was 9.2 x 10-''mm3/
kgf-kn+, the specific wear amount of the mating material (S45C) is 21
．． 4X10-'mm3/kgf-km, dynamic friction coefficient is 0
．． It was 244.

Comparative Example 1 100 parts by weight of the liquid crystal polycastil of the reference example and glass fiber (
Example 1 45 parts by weight of chopped strands (3 lengths)
The mixture was melt-kneaded and pelletized using the method described above. This polymer was injection molded under the same conditions as in the examples, and friction and wear tests were conducted using the obtained test pieces. As a result of measurement under the same conditions as in Example 1, the specific wear amount of the test piece was 21.0×10-”10m3
/kgf H)an, specific wear amount of mating material (S45C) 4
7.6X10-'ms+'/kgf・b, dynamic friction coefficient 0
．． It was 302.

Comparative Example 2 100 parts by weight of the liquid crystal polyester of the reference example, dimethylpolysiloxane (BY-16-1 manufactured by Toshi/Dow Corning)
40) 1.5 parts by weight and 45 parts by weight of glass fiber (chopped strand, 3rd grade) were melt-kneaded and pelletized by the method of Example 1. Furthermore, this polymer was used in Example 1.
Injection molding was performed under the same conditions as above, and a wear test was conducted using the obtained test piece. As a result, the test load was 10 kgf,
Specific wear amount at test speed V = 20 m/min is 18.0
Although the test piece showed a value of X10-''mm3/kgf.-, which was lower than that of the example, exudation of silicone was also observed from this test piece.

[Effects of the Invention] The liquid crystal polyester resin composition obtained by the present invention has the following properties:
The excellent heat resistance and mechanical properties of liquid crystal polyester
It is suitable for use in sliding parts because it has significantly improved wear resistance without compromising fluidity.

Claims (3)

[Claims] (1) Liquid crystal polyester consisting of the following structural units (I) to (IV) and forming an anisotropic melt phase with a deflection temperature under load of 190 to 280°C, a liquid crystal initiation temperature of 330°C or less, and a melt viscosity of 10,000 poise or less A liquid crystal polyester composition containing 0.5 to 20 parts by weight of powdered silicone (B) per 100 parts by weight of (A). ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・( I
) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(III
) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(IV) (However, the X in the formula ▲There are mathematical formulas, chemical formulas, tables, etc.)
, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There are tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
and ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and Y represents ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, There are chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas, chemical formulas,
There is a table, etc. ▼ indicating one or more groups selected from) (2) A liquid crystal polyester resin composition further comprising 200 parts by weight or less of an inorganic filler based on 100 parts by weight of the liquid crystal polyester resin composition according to claim (1). (3) The liquid crystal polyester resin composition according to claim (2), wherein the inorganic filler is glass fiber and/or carbon fiber.