JP2876644B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a resin composition capable of providing a molded article having extremely excellent heat resistance, fluidity and sliding properties and having small anisotropy.

<Prior art> In recent years, there has been an increasing demand for higher performance plastics, and a number of polymers having various new properties have been developed and marketed. Among them, optics characterized by a parallel arrangement of molecular chains. Anisotropic liquid crystal polymers have attracted attention because of their excellent fluidity and mechanical properties. However, what has been known as this liquid crystal polymer has a drawback that when it is used as a sliding part, it tends to be damaged by abrasion when used as a sliding part due to the large anisotropy of the molded article.

In order to improve the slidability, for example, for oxybenzoyl polyester, an organic silicon compound and an organic fluorine compound are added to the liquid crystal polymer (Japanese Patent Laid-Open No. 62-267353), a fluororesin, an insulating solid It is known to add a lubricant (JP-A-55-84321).

<Problems to be Solved by the Invention> However, Japanese Patent Application Laid-Open No.
-267353 and JP-A-55-84321 disclose compositions for use in sliding members because the oxybenzoyl polyester itself has a large anisotropy or has poor fluidity, so that a mold is used. There were problems such as limitations on design and molded product thickness.

<Means for Solving the Problems> The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention.

That is, the present invention relates to 100 parts by weight of a thermotropic liquid crystal polyester (A) having a deflection temperature under load of 190 to 280 ° C. comprising the following structural units, 0.5 to 50 parts by weight of a fluororesin and / or a lubricant (B), and a filler (C). A) providing a resin composition comprising 5 to 100 parts by weight;

(However, X in the formula is Is required, and And two or more groups selected from —CH ₂ —CH ₂ —.
Y is And Z represents a hydrogen atom or a chlorine atom. The structural unit (II) is
It is substantially equimolar to I). Further, the present invention is a sliding material comprising the above resin composition.

The structural unit (I) of the thermotropic liquid crystal polyester (A) in the present invention is a structural unit generated from p-hydroxybenzoic acid, and the structural unit (II) is 4,
Structural unit formed from 4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-
3,3 ', 5,5'-tetramethyldihydroxybiphenyl,
Structural units formed from one or more dihydroxy compounds selected from t-butylhydroquinone, methylhydroquinone, phenylhydroquinone, 2,6-dihydroxynaphthalene and ethylene glycol, wherein the structural unit (III) is terephthalic acid, isophthalic acid, , 6'-dicarboxynaphthalene, 1,2'-bis (phenoxy) ethane-4,4'-dicarboxylic acid and 1,2'bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid And structural units formed from one or more dicarboxylic acids.

The structural unit (II) is substantially equimolar to the structural unit (III).

The thermotropic liquid crystal polyester (A) of the present invention is a copolymer comprising the above structural units (I), (II) and (III).

The copolymerization amount of the structural units (I) and (II) is arbitrary. However, the following copolymerization amount is preferred from the viewpoint of fluidity. That is, the structural unit (I) is preferably 40 to 90 mol%, particularly preferably 60 to 85 mol%, based on the total of the structural units (I) and (II).

One of the structural units (II) is 4,4'-dioxybiphenyl When the dioxy compound other than 4,4′-dioxybiphenyl is dioxyethylene (X = —CH ₂ —CH ₂ —), (I) Is preferably 7.5 / 2.5 to 9.5 / 0.5, and OCH ₂ CH ₂ O
Is preferably 23 to 5 mol% based on the total of the structural units (I) and (II).

On the other hand, when the dioxy compound other than 4,4'-dioxybiphenyl is other than dioxyethylene, And the molar ratio of the other dioxy compound to 7.5 / 2.5 to 3/7
Is preferred, X = One or more dioxy compounds selected from
But 2,6-dioxynaphthalene is particularly preferred.

The structural unit (III) is preferably terephthalic acid.

The thermotropic liquid crystal polyester (A) in the present invention has a deflection temperature under load (hereinafter referred to as HDT) of 190 to 190.
It is essential that the temperature is 280 ° C.

If the HDT is lower than 190 ° C., the effect of improving the heat resistance is insufficient, and if it exceeds 280 ° C., there arises a problem that the molding temperature of the obtained resin composition increases.

Here, HDT is based on ASTM D648.
This is a value measured at a stress of 8.6 kg / cm ² .

The method for producing the thermotropic liquid crystal polyester (A) in the present invention is not particularly limited, and can be produced according to a known polyester polycondensation method.

For example, in the above structural units (II), -X- is -CH ₂ CH ₂ -
Otherwise (1) ~ (4), - X- is -CH ₂ CH ₂ - in the case of the production method of (5) are preferred.

(1) A method of producing from a diacylated aromatic dihydroxy compound such as p-acetoxybenzoic acid or 4,4'-diacetoxybiphenyl and an aromatic dicarboxylic acid such as terephthalic acid by a deacetic acid polycondensation reaction.

(2) An acetic anhydride is reacted with an aromatic dihydroxy compound such as p-hydroxybenzoic acid and 4,4'-dihydroxybiphenyl, and an aromatic dicarboxylic acid such as terephthalic acid to acylate a phenolic hydroxyl group and then to remove acetic acid. A method of producing by a polycondensation reaction.

(3) phenyl ester of p-hydroxybenzoic acid, 4,
A method of producing from an aromatic dihydroxy compound such as 4'-dihydroxybiphenyl and a diphenyl ester of an aromatic dicarboxylic acid such as terephthalic acid by a phenol removal polycondensation reaction.

(4) A desired amount of diphenyl carbonate is reacted with an aromatic dicarboxylic acid such as p-hydroxybenzoic acid and terephthal to form a diphenyl ester.
A method in which an aromatic dihydroxy compound such as 4'-dihydroxybiphenyl is added, and the mixture is produced by a dephenol polycondensation reaction.

(5) A method according to (1) or (2) in the presence of polyethylene terephthalate.

Typical catalysts used in the polycondensation reaction include stannous acetate, tetrabutyl titanate, potassium acetate, antimony trioxide, magnesium, and metal compounds such as sodium acetate, and are particularly effective for dephenol polycondensation. is there.

Thermotropic liquid crystal polyester (A) of the present invention
Can measure the intrinsic viscosity in pentafluorophenol, in which case 0.1 g / dl concentration of 6
The value measured at 0 ° C. is preferably 0.5 or more, particularly 1.0 to 15.0
Is preferred. And when -X- is -CH ₂ CH _2- ,
~ 3.0 is preferred.

Further, the melt viscosity of the aromatic polyester of the present invention is 10 to
20,000 poise is preferred, and 20 to 10,000 poise is more preferred.

The melt viscosity is a value measured by a Koka type flow tester under the condition of (liquid crystal onset temperature + 40 ° C.) and a shear rate of 1,000 (1 / second).

When the aromatic polyester of the present invention is polycondensed, in addition to the structural units (I) to (III), 4,4′-diphenyldicarboxylic acid, 3,3′-diphenyldicarboxylic acid,
Aromatic dicarboxylic acids such as 3,4'-diphenyldicarboxylic acid and 2,2'-diphenyldicarboxylic acid; alicyclic dicarboxylic acids such as hexahydroterephthalic acid; aromatic compounds such as resorcinol, chlorohydroquinone and 2,7-dihydroxynaphthalene Group dihydroxy compound, m-oxybenzoic acid,
Aromatic oxycarboxylic acids such as 2,6-oxynaphthoic acid and p-aminophenol, p-aminobenzoic acid and the like can be further copolymerized in a small proportion that does not impair the object of the present invention.

In addition to the above components in the aromatic polyester of the present invention, for example, an aromatic imide dicarboxylic acid represented by the following formula, (However, Ar represents a divalent aromatic residue.) Aromatic imidohydroxycarboxylic acid, And aromatic imidodihydroxy compounds Such an aromatic imide compound capable of forming a polyester may be copolymerized as long as the object of the present invention is not impaired.

Examples of the fluororesin and / or lubricant (B) used in the present invention include, for example, polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorotrifluoroethylene-fluorine as the fluororesin. Polyvinylidene fluoride copolymer, polyvinylidene fluoride, polyvinyl fluoride, and the like are particularly preferred.Polytetrafluoroethylene powder is preferable, and as a lubricant other than fluororesin, a solid lubricant such as molybdenum disulfide, graphite and silicone are used. Heat resistant oily lubricants such as oils are included.

Further, the filler (C) used in the present invention includes, for example, glass fiber, carbon fiber, aromatic polyamide fiber, potassium titanate fiber, stone fiber, brass fiber, stainless fiber, steel fiber, ceramic fiber, boron whisker Fiber, mica, talc, silica, calcium carbonate, glass beads, glass flakes, glass microballoons, clay, wollastenite, aluminum oxide,
Examples include iron oxide, zinc oxide, titanium dioxide, and tin oxide.

The resin composition of the present invention contains 0.5 to 50 parts by weight of a fluororesin and / or a lubricant (B), preferably 100 parts by weight of the thermotropic liquid crystal polyester (A).
2.0 to 10.0 parts by weight and the filler (C) must be 5 to 100 parts by weight, preferably 20 to 50 parts by weight.

If the amount of the fluororesin and / or the lubricant (B) is less than 0.5 part by weight, the abrasion resistance is insufficient, and if it exceeds 50 parts by weight, the heat resistance and mechanical properties become insufficient.

Further, if the amount of the filler (C) is less than 5 parts by weight, the anisotropy of the mechanical properties becomes large, and if it exceeds 100 parts by weight, the abrasion resistance with metal becomes insufficient.

The resin composition of the present invention is preferably melt-kneaded,
Known methods can be used for the melt-kneading. For example, the composition can be melt-kneaded at a temperature of 200 to 400 ° C. using a Banbury mixer, a rubber roll machine, a kneader, a single-screw or twin-screw extruder, and the like to obtain a composition.

Further, the resin composition of the present invention, a known antioxidant,
Thermal decomposition inhibitor, hydrolysis inhibitor, colorant (pigment, dye), conductive agent such as carbon black, flame retardant, lubricant,
A nucleating agent, a release agent, a plasticizer, an adhesion aid, a pressure-sensitive adhesive and the like can be arbitrarily contained.

Since the resin composition thus obtained has excellent heat resistance and fluidity and small anisotropy, it can be used as a sliding material having excellent wear resistance.

<Example> Hereinafter, the present invention will be described in more detail with reference to examples.

Reference Example 1 608 parts by weight of p-acetoxybenzoic acid, 122 parts by weight of 4,4'-diacetoxybiphenyl, 75 parts by weight of terephthalic acid and 130 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 were equipped with a stirring blade and a distillation tube. The reaction vessel was charged and subjected to deacetic acid polymerization.

First, after reacting at 250-300 ° C for 2.5 hours under a nitrogen gas atmosphere, the pressure was reduced to 0.2 mmHg at 300 ° C, and the reaction was further performed for 3.25 hours to complete the polycondensation. A resin (a) having the following theoretical structural formula was obtained.

l / m / n / o = 75/10/15/25 Moreover, as a result of placing this polyester on a sample stage of a polarizing microscope and raising the temperature to confirm the optical anisotropy, the liquid crystal onset temperature was 264 ° C. And showed good optical anisotropy. The logarithmic viscosity of this polyester (measured in pentafluorophenol at 60 ° C. at a concentration of 0.1 g / dl) was 1.25.

Reference Example 2 1105 parts by weight of p-hydroxybenzoic acid, 247.7 parts by weight of 4,4'-dihydroxybiphenyl, 163.7 parts by weight of 2,6-diacetoxynaphthalene, 1197.6 parts by weight of acetic anhydride, and 332.3 parts by weight of terephthalic acid were stirred with a stirring blade and distilled. Charge into a reaction vessel equipped with an outlet tube, and in a nitrogen gas atmosphere at 100 to 250 ° C for 5 hours,
After reacting at ~ 330 ° C for 2.5 hours, 1.
When the pressure was reduced to 0 mmHg and the reaction was further performed for 1.5 hours to complete the polycondensation, almost the theoretical amount of acetic acid was distilled off, and a resin (b) having the following structural formula was obtained.

l / m / n / o = 80 / 13.3 / 6.7 / 20 The polyester was placed on the sample stage of a polarizing microscope and heated to confirm the optical anisotropy. And showed good optical anisotropy. The logarithmic viscosity of the polyester (measured under the same conditions as in Reference Example 1) was 6.2 dl / g.

Comparative Examples 1-2 Thermotropic liquid crystal polyesters (a)-(b) of Reference Examples 1-2 were used as Sumitomo Nestal injection molding machine Promat.
40/25 (manufactured by Sumitomo Heavy Industries, Ltd.), 1/8 "thickness 1/2" at cylinder temperature 300 ~ 350 ℃, mold temperature 90 ℃
Test piece of width x 5 "length, outer diameter 25mmφ, inner diameter 19mmφ,
30mm long cylindrical test piece and 2mm thick x 70mm x 70m
m square plate was formed.

And HDT is 1/8 ″ using HDT measuring device made by Toyo Seiki
The HDT (18.6 kg / cm ² ) of the thick test piece was measured.

In the abrasion test, the above-mentioned cylindrical test piece was used to measure the abrasion coefficient and the specific abrasion amount using Orientec Co., Ltd. model EFM-III-EN.

Then, the square plate was cut into a width of 14 mm in the flow direction and the direction perpendicular thereto, and the flexural modulus was measured using Tensilon UTM-100 manufactured by Toyo Baldwin Co. under the conditions of a strain rate of 1 mm / min and a span distance of 40 mm.

HDT, the first in accordance with the measurement results of bending test and wear test
It is shown in the table.

Examples 1-3 Thermotropic Liquid Crystal Polyester of Reference Example 1 (a)
100 parts by weight, a fluororesin and / or a lubricant (B) and a filler (C) shown in Table 1 were blended in the same manner as in Comparative Examples 3 to 5, and melt-mixed at a set temperature of 300 to 360 ° C., and pelletized. After that, cylinder temperature 300 ~ 360 ℃, mold temperature 90 ℃
The test piece and the square plate were injection molded. As the fluororesin, powder of polytetrafluoroethylene (“Polyflon TFE” M-12 manufactured by Daikin Industries, Ltd.) is used. As the glass fiber, a chopped strand E of 9 μm in diameter and 3 mm in length is used.
Glass fiber was used.

Table 1 shows the measurement results of the flexural strength, HDT, wear test, and anisotropy of flexural modulus.

Compared with Comparative Example 1, it is excellent in flexural strength and HDT, the ratio of flexural modulus is as small as 2.6 to 2.7, and is excellent in wear resistance despite small anisotropy.

Example 4 Thermotropic liquid crystal polyester of Reference Example 2 (b)
Table 1 shows the test results of the melt-mixed and injection-molded test pieces and the square plates in the same manner as in Examples 1 to 3 at 100 parts by weight and the weight ratio shown in Table 1.

 The specific wear amount is smaller than that of Comparative Example 2.

Comparative Examples 3 to 5 After mixing with a composition shown in Table 1 using a Henschel mixer and melt-mixing with a 30 mmφ twin screw extruder at a set temperature of 280 to 360 ° C., the mixture was extruded in a gut shape and pelletized with a strand cutter. Test pieces and square plates were formed at a cylinder temperature of 280 to 360 ° C and a mold temperature of 60 to 90 ° C in the same manner as in Examples 1 and 2.

Table 1 shows the measurement results of the HDT, bending test and wear test.

In Comparative Example 3, since the filler (C) was not contained, the anisotropy of the flexural modulus was large.

In Comparative Example 4, a fluororesin and / or a lubricant (B)
The wear resistance is reduced due to no inclusion.

In Comparative Example 5, where the fluororesin and / or the lubricant (B) were changed, the wear resistance was poor at 0.3 parts by weight, and the bending strength and heat resistance were significantly reduced at 60.0 parts by weight.

Comparative Examples 6 and 7 It can be seen that the commercially available liquid crystal polyester resins 8 and 9 have insufficient wear resistance and large anisotropy.

<Effect of the Invention> Since the resin composition of the present invention has excellent heat resistance and fluidity and low anisotropy, it can be used as a sliding material having excellent wear resistance.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08G 63/60 C08L 67/00-67/04

Claims (2)

(57) [Claims] 1. A thermotropic liquid crystal polyester (A) having a deflection temperature under load of 190 to 280 DEG C., 100 parts by weight, a fluororesin and / or a lubricant (B) 0.5 to 50, comprising the following structural units (I) to (III): Parts by weight and filler (C) 5 to 100
A resin composition comprising parts by weight. (However, X in the formula is Is required, and And at least one group selected from —CH ₂ —CH ₂ —.
Y is And Z represents a hydrogen atom or a chlorine atom. The structural unit (II) is
It is substantially equimolar to I). ) 2. A sliding material comprising the resin composition according to claim 1.