JP2830123B2 - Liquid crystal polyester resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal polyester resin composition having excellent heat resistance, moldability, fluidity, and mechanical properties, particularly high weld strength.

<Prior art> In recent years, there has been an increasing demand for higher performance of plastics, and a number of polymers having various new properties have been developed and marketed. Among them, the polymer is characterized by a parallel arrangement of molecular chains. Optically anisotropic liquid crystal polymers have attracted attention because of their excellent mechanical properties.

Examples of the polymer forming the anisotropic molten phase include p-
Liquid crystal polymer obtained by copolymerizing hydroxybenzoic acid with polyethylene terephthalate (JP-A-49-72393) and liquid crystal polymer obtained by copolymerizing p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (JP-A-54-72393) No. 77691), and a liquid crystal polymer obtained by copolymerizing p-hydroxybenzoic acid with 4,4′-dihydroxyphenyl, terephthalic acid, and isophthalic acid (Japanese Patent Publication No. 57-24407).

It is also known to mix glass fibers for the purpose of improving the heat resistance and weld strength of the liquid crystal polymer.

<Problems to be Solved by the Invention> However, as this liquid crystal polymer, the heat deformation temperature is as low as less than 190 ° C. and the heat resistance is insufficient or the heat deformation temperature is 190 ° C. Although the heat resistance is good as described above, the liquid crystal starting temperature is too high and molding cannot be performed unless the temperature is 400 ° C. or higher, and a liquid crystal polymer having a balance between heat resistance, moldability, fluidity such as high melt viscosity is not obtained. It was difficult.

Further, in order to improve the weld strength of the molded product of the liquid crystal polymer, blending of glass fibers has been attempted, but the effect of improving the weld strength is not necessarily large, and there is a problem that the fluidity is greatly reduced.

Therefore, an object of the present invention is to solve the above-mentioned problems and to obtain a liquid crystal polyester resin composition having excellent heat resistance, moldability, and fluidity, and having high mechanical properties, particularly, high weld strength of a molded article.

<Means for Solving the Problems> That is, the present invention provides a polyester comprising the following structural units (I), (II) and (IV) or the following structural units (I), (II), (III) and (IV): Polyester having a liquid crystal onset temperature of 330 ° C. or lower and a melt viscosity of 1
The present invention relates to a liquid crystal polyester resin composition comprising 99 to 22% by weight of a liquid crystal polyester (A) forming an anisotropic molten phase of not more than 0.000 poise and 1 to 80% by weight of a zinc oxide whisker (B) in a tetrapod form.

(However, R ₁ in the formula is It represents one or more groups selected from, R ₂ is Represents a group selected from X is chlorine or hydrogen. The structural unit (IV) is substantially a structural unit [(II) + (II
I)]. The present invention also relates to the above-mentioned liquid crystal polyester resin composition further comprising glass fiber in an amount of less than 200 parts by weight, based on 100 parts by weight of the total of the liquid crystal polyester (A) and the tetrapod-shaped zinc oxide whisker (B). It is a molded article having a weld portion made of a liquid crystal polyester resin composition.

The structural unit (I) of the liquid crystal polyester (A) in the present invention is a structural unit formed from p-hydroxybenzoic acid, and the structural unit (II) is 4,4'-dihydroxybiphenyl, 3,3 ', 5 , 5'-tetramethyl-4,4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, 2,6'-dihydroxynaphthalene, 2,7-dihydroxynaphthalene,
2,2-bis (4-hydroxyphenyl) propane and
The structural unit generated from 4,4'-dihydroxydiphenyl ether, the structural unit (III) is a structural unit generated from ethylene glycol, the structural unit (IV) is terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid,
A kind selected from 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic acid, and 1,2-bis (2-chlorophenoxy) ethane-4,4-dicarboxylic acid The structural units generated from the above aromatic dicarboxylic acids are respectively shown.

The liquid crystal polyester in the present invention is a polyester comprising the above structural units (I), (II) and (IV) or the following structural units (I), (II), (III) and (IV)
It is a polyester consisting of

The structural units (I), (II), (III) and (IV)
Is arbitrary. However, the following copolymerization amount is preferred from the viewpoint of fluidity. That is, when the structural unit (III) is contained, the structural units (I) and (II)
Is 60 times the sum of (I), (II) and (III).
To 95 mol%, particularly preferably 80 to 92 mol%. Further, the content of the structural unit (III) is preferably from 40 to 5 mol%, particularly preferably from 20 to 8 mol%, based on the total of the structural units (I), (II) and (III). The molar ratio [(I) / (II)] of the structural units (I) and (II) is preferably from 75/25 to 95/5, and the structural unit (IV) is the same as that of the structural units (II) and (III). Substantially equimolar to the sum. On the other hand, when the structural unit (III) is not contained, the structural unit (I) is replaced with the structural units (I) and (I
It is preferably from 40 to 90 mol%, particularly preferably from 60 to 88 mol%, based on the total of I), and the structural unit (IV) comprises
It is substantially equimolar to I).

The liquid crystal onset temperature of the liquid crystal polyester (A) is 33
It is essential that the temperature is 0 ° C. or lower, and it is preferably 240 to 330 ° C. in view of fluidity and heat resistance.

If the liquid crystal onset temperature exceeds 330 ° C., the molding temperature needs to be increased, which is not practical in terms of moldability.

The melt viscosity is essential to be 10,000 poise or less, preferably 6,000 poise or less, and more preferably 4,000 poise or less.

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).

The method for producing the 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, when the above structural unit (III) is not contained, the following production methods (1) to (4) are preferably used, and when the above structural unit (III) is contained, the production method (5) is preferably used.

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

(2) After reacting aromatic dihydroxy compounds such as p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl and hydroquinone, and aromatic dicarboxylic acids such as terephthalic acid with acetic anhydride to acylate the phenolic hydroxyl group, A method of producing by a deacetic acid polycondensation reaction.

(3) phenyl ester of p-hydroxybenzoic acid, 4,
A method of producing from an aromatic dihydroxy compound such as 4'-dihydroxybiphenyl or hydroquinone 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 aromatic dicarboxylic acids such as p-hydroxybenzoic acid and terephthalic acid to form diphenyl esters, respectively.
A method in which an aromatic dihydroxy compound such as 4,4'-dihydroxybiphenyl or hydroquinone is added, and the mixture is produced by a phenol removal polycondensation reaction.

(5) A method according to (1) or (2) in the presence of an oligomer or polymer comprising ethylene glycol and an aromatic dicarboxylic acid or a bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid.

According to the production method (5), the oligomer or polymer composed of ethylene glycol and aromatic dicarboxylic acid is randomly incorporated into the molecular chain by a transesterification reaction, and a liquid crystal polyester containing the structural unit (III) is obtained. Conceivable.

At the time of the polymerization reaction, a catalyst may be used if necessary. Catalysts used for the polycondensation reaction include stannous acetate, tetrabutyl titanate, potassium acetate, antimony trioxide,
Metal compounds such as magnesium, sodium acetate, and zinc acetate are typical, and are particularly effective for dephenol polycondensation.

The liquid crystal polyester (A) in the present invention is capable of measuring a fixed viscosity in pentafluorophenol, in which case the value measured at 60 ° C. at a concentration of 0.1 g / dl is 0.5 dl / g. The above is preferable, and when containing the structural unit (III), it is particularly preferably 0.5 to 3.0 dl / g, and when not containing the structural unit (III), it is particularly preferably 1.0 to 15.0 dl / g.

When the liquid crystal polyester (A) used in the present invention is polycondensed, the above (I), (II), (III) and (I)
V) In addition to the constituents, aromatic dicarboxylic acids such as 3,3'-diphenyldicarboxylic acid, 3,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, and alicyclic rings such as hexahydroterephthalic acid Aromatic dihydroxy compounds such as formula dicarboxylic acid, resorcin, chlorohydroquinone, methylhydroquinone, bis (4-hydroxyphenyl) sulfone, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexane Diols, aliphatic and alicyclic diols such as 1,4-cyclohexanedimethanol and aromatic hydroxycarboxylic acids such as m-oxybenzoic acid and 6-hydroxy-2-naphthoic acid and n-aminophenol, p-aminobenzoic acid Acid and the like are further copolymerized in a small proportion so as not to impair the purpose of the present invention. Can be

The tetrapod-like zinc whisker (B) used in the present invention has a single-crystal needle-like shape, and has a three-dimensional tetrapot-like shape in which crystals grow in the vertex direction of a tetrahedron. As expected. The average fiber length of one whisker is preferably from 1 to 500 μm, particularly preferably from 2 to 15 μm.

The surface of the tetrapod-shaped zinc oxide whisker (B) is coupled with a coupling agent such as γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxy. Orchid, methyltrimethoxysilane, γ-
Silane coupling agents such as anilinopropyltrimethoxysilane, hydroxypropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, and vinylacetoxysilane; isopropyltrisisostearoyl titanate; isopropyltris (dioctylpyrophosphate) titanate; Titanate couplings such as N-aminoethyl-aminoethyl) titanate, tetraoctylbis (ditridecylphosphite) titanate, bis (dioctylpyrophosphate) ethylene titanate, isopropyltridecylbenzenesulfonyl titanate, isopropyltri (dioctylphosphate) titanate Agent or
It may be used after being subjected to a coupling treatment with an aluminum-based coupling agent such as acetoalkoxyaluminum diisopropylate and a zircoaluminate-based coupling agent.

Glass fibers may be further added to the composition of the present invention. Preferable specific examples of the glass fiber include a chopped strand having a diameter of 5 to 15 μm and a roving type glass fiber for a general reinforcing resin.

1 to 6 m from the viewpoint of handling properties and imparting surface gloss of molded products
An m-length chopped strand is particularly preferably used.

The glass fiber which has been subjected to a normal coupling agent treatment such as a silane type or a titanium type is preferably used, and may be treated with a normal sizing agent such as an epoxy resin or vinyl acetate.

In the present invention, the compounding amount of the liquid crystal polyester (A) is 99 to 20% by weight, preferably 95 to 30% by weight, and the compounding amount of the tetrapod-shaped zinc oxide whisker (B) is 1 to 80% by weight, preferably 5 to 70% by weight, and the amount of glass fiber added is preferably less than 200 parts by weight based on 100 parts by weight of the total of the liquid crystal polyester (A) and the tetrapotted zinc oxide whisker (B), 5-150 parts by weight are particularly preferred. When the compounding amount of the liquid crystal polyester (A) exceeds 99% by weight with respect to the total of the liquid crystal polyester (A) and the tetrapotted zinc oxide whisker (B), heat resistance is obtained.
The effect of improving the mechanical properties is insufficient, and if it is less than 20% by weight, the moldability and the fluidity are remarkably reduced, which is not practical.

The composition of the present invention contains an antioxidant and a heat stabilizer (for example, hindered fer), hydroquinone, phosphites and their substituted substances, and an ultraviolet absorber to the extent that the object of the present invention is not impaired. (Eg, resorcinol, salicylate, benzotriazole, benzophenone, etc.), lubricants and release agents (eg, montanic acid and its salts, esters, half esters thereof, stearyl alcohol, stearamide, and polyethylene wax), dyes (eg, nitrosine) and pigments (For example, cadmium sulfide, phthalocyanine, carbon black, etc.), and other additives such as a colorant, a flame retardant, a plasticity, an antistatic agent, other fillers, a reinforcing agent, and other thermoplastic resins. Characteristic can be imparted.

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.

The resin composition thus obtained can be molded by a method such as injection molding, and particularly, because of its excellent weld strength,
A molded article having a weld portion can be obtained.

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

Reference Example 1 466 parts by weight of p-hydroxybenzoic acid, 84 parts by weight of 4,4'-dihydroxybiphenyl, 480 parts by weight of acetic anhydride, 75 parts by weight of terephthalic acid and 130 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 dl / g The reaction vessel was equipped with a stirring blade and a distilling tube, and subjected to deacetic acid polycondensation under the following conditions.

First, under nitrogen atmosphere, 100 ~ 250 ℃ for 5 hours, 250 ~ 3
After reacting at 00 ° C for 1.5 hours, 0.5mmH at 300 ° C for 1 hour
g, and the mixture was further reacted for 2.25 hours to complete the polycondensation. As a result, almost the theoretical amount of acetic acid was distilled off, and a resin having the following theoretical structural formula was obtained.

k / l / m / n = 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 at 60 ° C. in pentafluorophenol at a concentration of 0.1 g / dl) is 1.96 dl / g,
The melt viscosity at 304 ° C. and a shear rate of 1,000 / sec was 910 poise.

Reference Example 2 541 parts by weight of p-acetoxybenzoic acid, 184 parts by weight of 4,4'-diacetoxybiphenyl, 62 parts by weight of hydroquinone diacetate, 124 parts by weight of terephthalic acid, and 42 parts by weight of isophthalic acid were stirred with a stirring blade and a distillation tube. After reacting at 250 to 360 ° C. for 3 hours under a nitrogen gas atmosphere, the pressure was reduced to 1 mmHg, and the mixture was further heated for 1 hour to complete the polycondensation. ) Got.

k / l / m / n / o = 75 / 13.3 / 6.7 / 18.75 / 6.25 This polyester was placed on a sample stage of a polarizing microscope and heated to confirm the optical anisotropy.
The temperature was 5 ° C, showing good optical anisotropy. The logarithmic viscosity of this polyester (measured under the same conditions as in Reference Example 1) is 4.1 dl /
g, melt viscosity at 345 ° C and shear rate of 1,000 / sec is 3500
Poise.

Examples 1 to 5, Comparative Examples 1 and 2 A liquid crystal polyester (A), a tetrapod-shaped zinc oxide whisker (B), and a glass fiber (C) were used. It was melt-mixed by a screw extruder to obtain a resin composition.

The obtained resin composition is supplied to Sumitomo Nestal injection molding machine Promat 40/25 (manufactured by Sumitomo Heavy Industries, Ltd.), and the cylinder temperature is 300 to 360 ° C. and the mold temperature is 100 ° C., 1/8 ″.
× 1/2 ″ × 5 ″ test pieces and ASTM No. 4 dumbbells were molded. ASTM No. 4 dumbbells were formed using both a conventional mold (dumbbell I) with a gate at one end of the dumbbell and a weld mold (dumbbell II) with gates at both ends of the dumbbell. The deflection temperature under load of a 1/8 ″ thick test piece (18.6 kgf / cm ² ) was measured in accordance with the ASTM D648 standard. Dumbbells against Dumbbell I
The ratio of the breaking strength of II was defined as the weld strength retention.

Comparative Examples 3 and 4 Using the liquid crystal polyesters (A) of Reference Examples 1 and 2,
As in Examples 1 to 5 and Comparative Examples 1 and 2, the cylinder temperature was 300 to
A test piece of 1/8 "x 1/2" x 5 "and an ASTM No. 4 dumbbell were formed at 350 ° C and a mold temperature of 100 ° C.

Then, the deflection temperature under load, the breaking strength, and the melt viscosity were measured, and the weld strength retention was calculated. The results are shown in the table.

Comparative Example 5 having the following theoretical structural formula, and having a liquid crystal onset temperature of 359 ° C. and 399
Using a liquid crystal polyester having a melt viscosity of 8,800 poise at a temperature of 1000 ° C. and a shear rate of 1,000 / second, a tetrapod-shaped zinc oxide whisker (B) and a glass fiber (C) were melted at the ratios shown in the table in the same manner as in Examples 1 to 5. Mixing (set temperature 400 ° C.), molding (cylinder temperature 400 ° C., mold temperature 210 ° C.) were evaluated.
The results are shown in the table.

l / m / n = 67/33/33 In comparison with Comparative Examples 1 to 5, the resin compositions of Examples 1 to 5 of the present invention have a balance between the deflection temperature under load and the melt viscosity,
Excellent heat resistance and fluidity. In addition, the weld strength retention is as high as 26% or more, and it has excellent mechanical properties.

The resin composition of Comparative Example 5 has a high deflection temperature under load, but has a high melt viscosity at 400 ° C. of the extrusion and molding temperatures of 16000 poise and low fluidity. When the molding temperature exceeded 400 ° C., generation of pyrolysis gas was observed. Also, the weld strength retention was as low as 8%.

<Effects of the Invention> The present invention is excellent in heat resistance, moldability, and fluidity by adding a tetrapod-shaped zinc oxide whisker and, if necessary, glass fiber to a specific liquid crystal polyester having a limited structural formula. Thus, a resin composition having high mechanical properties, particularly high weld strength, can be obtained.

Claims (3)

(57) [Claims] 1. The following structural units (I), (II) and (IV)
Or the following structural units (I), (I)
(A) a polyester comprising (I), (III) and (IV), which forms an anisotropic molten phase having a liquid crystal onset temperature of 330 ° C. or less and a melt viscosity of 10,000 poise or less.
A liquid crystal polyester resin composition comprising 99 to 22% by weight and 1 to 80% by weight of a tetrapod-shaped zinc oxide whisker (B). (However, R ₁ in the formula is It represents one or more groups selected from, R ₂ is Represents a group selected from X is chlorine or hydrogen. The structural unit (IV) is substantially equimolar to the sum of the structural units (II) and (III). ) 2. A total of 100 parts by weight of the liquid crystal polyester (A) and the tetrapod-shaped zinc oxide whisker (B),
The liquid crystal polyester resin composition according to claim 1, further comprising less than 200 parts by weight of glass fiber. 3. A molded article having a weld portion comprising the liquid crystal polyester resin composition according to claim 1.