JPH09143347A - Liquid crystal polyester resin mixture and method for molding the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal polyester resin mixture which itself can be stably plasticized during molding and can be stably molded to give a molding excellent in mechanical properties and heat stability and to provide a method for molding the same. SOLUTION: This liquid crystal polyester resin mixture is prepared by mixing 100 pts.wt. liquid polyester composition mainly consisting of 100 pts.wt. liquid crystal polyester and 0-150 pts.wt. filler with 0.001-5 pts.wt. higher fatty acid ester at below the flow temperature at which the melt viscosity is 48,000P when the resin heated at a rising rate of temperature of 4 deg.C/min is extruded through a nozzle of an inside diameter of 1mm and a length of 10mm under a load of 100kgf/cm<2> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal polyester which is capable of stable plasticization of a liquid crystal polyester during molding and can be stably molded, and which provides a molded product excellent in mechanical properties and thermal stability. The present invention relates to a resin mixture and a method for molding a liquid crystal polyester using the liquid crystal polyester resin mixture.

[0002]

2. Description of the Related Art Since liquid crystal polyesters are rigid, molecules do not become entangled even in a molten state to form a polydomain having a liquid crystal state, and a molecular chain exhibits a behavior of remarkably aligning in a flow direction at a low shear rate. It is called liquid crystal type (thermotropic liquid crystal) polymer. Liquid crystal polyester has extremely excellent melt fluidity due to this peculiar behavior, and has a heat distortion resistance of 300 ° C or more depending on the structure, and is a molded product for applications such as electronic parts, OA, AV parts, and heat-resistant tableware. Is used for.

As a molding method for obtaining these molded bodies,
It is common to use an extruder using a screw such as injection molding or extrusion molding. At this time, the liquid crystal polyester often had a problem of instability in its plasticizing process. That is, the plasticization time is not constant and becomes unstable, and in the injection molding, there are cases where the plasticization does not end within the cooling time, molding cannot be performed in a constant cycle, and productivity decreases and at the same time The quality could be adversely affected.

The reason why the plasticizing time of the liquid crystal polyester becomes unstable is not clear, but one of the causes is that the melt viscosity of the liquid crystal polyester itself has a large dependence on the shear rate and the temperature. It can be mentioned that only the surface is selectively plasticized and the fusion tends to occur.

As means for suppressing such a phenomenon, Japanese Patent Laid-Open No. 125259/1993 discloses the use of a composition prepared by mixing a higher fatty acid metal salt and a higher fatty acid with a thermotropic liquid crystal polymer. ing.
Further, JP-A-5-125258 discloses that stable plasticization can be achieved by using a particle mixture of thermotropic liquid crystal polymer particles and a higher fatty acid metal salt.

However, in any case, since a higher fatty acid or a metal salt thereof which decomposes at a high temperature is used together with a liquid crystal polymer having high heat resistance, when a molded product of the liquid crystal polymer is obtained, a gas in a molding machine is used. Since it is difficult to carry out stable molding work due to the large number of occurrences, and there is concern that the thermal stability of the obtained molded product may decrease, it is not always sufficient for the purpose of higher practicality. is not.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and the resin mixture itself is stably plasticized during molding so that stable molding can be performed, and the mechanical properties and It is an object of the present invention to provide a liquid crystal polyester resin mixture which gives a molded article having excellent thermal stability, and a method for molding a liquid crystal polyester using the liquid crystal polyester resin mixture.

[0008]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that liquid crystal polyester or a liquid crystal polyester resin composition containing a liquid crystal polyester and a filler as main components is added to a higher fatty acid. The inventors have found that a liquid crystal polyester resin mixture that achieves the above object can be obtained by blending a specific amount of ester, and that by using the mixture, the liquid crystal polyester can be stably plasticized during molding and processing, leading to the present invention.

That is, the present invention provides a liquid crystal polyester 1
100 parts by weight of a liquid crystal polyester resin composition mainly composed of 00 parts by weight and 0 to 150 parts by weight of a filler and 0.001 to 5 parts by weight of a higher fatty acid ester are approximately liquid crystal polyester resin composition measured by the following method. The present invention relates to a liquid crystal polyester resin mixture characterized by being mixed at a temperature lower than a flow temperature and a method for molding a liquid crystal polyester using the same. Flowing temperature: Resin heated at a temperature rising rate of 4 ° C./min under a load of 100 kgf / cm ² , inner diameter 1 mm, length 10
When extruded from mm nozzle, melt viscosity is 48000
It is the temperature that indicates poise.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal polyester used in the present invention is a polyester called a thermotropic liquid crystal polymer, which comprises (1) a combination of an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid. (2) a reaction product of a different aromatic hydroxycarboxylic acid, (3) a reaction product of a combination of an aromatic dicarboxylic acid and an aromatic diol, and (4) a reaction of a polyester such as polyethylene terephthalate with an aromatic hydroxycarboxylic acid. 400 ° C.
It forms an anisotropic melt at the following temperatures. In addition, in place of these aromatic dicarboxylic acids, aromatic diols, and aromatic hydroxycarboxylic acids, ester-forming derivatives thereof may be used.

Examples of the repeating structural unit of the liquid crystal polyester include the following, but are not limited thereto.

Repeating structural unit derived from aromatic hydroxycarboxylic acid:

Embedded image

Repeating structural unit derived from aromatic dicarboxylic acid:

Embedded image Repeating structural unit derived from aromatic diol:

[0014]

Embedded image

[0015]

Embedded image

A particularly preferable liquid crystal polyester in view of the balance of heat resistance, mechanical properties and processability is _one containing at least 30 mol% of the repeating structural unit represented by the formula A ₁ .

Specifically, the combinations of repeating structural units are preferably those represented by the following formulas (a) to (f). (A): (A ₁ ), (B ₁ ) or (B ₁ ) and (B ₂ )
A mixture of (C ₁ ). (B): (A ₁ ), (A ₂ ). (C) in those combinations of the structural units of :( a), that replaces the part of A ₁ in A _2. (D) In those combinations of the structural units of :( a), that replaces the part of B ₁ in B _3. (E) in what combination of structural units of :( a), that replaces the part of the C ₁ at C _3. (F): a combination of the structural units of (b) with the addition of the structural units of B ₁ and C ₁ . The liquid crystal polyesters having the basic structures (a) and (b) are described in, for example, JP-B-47-47870.
And JP-B-63-3888.

In the present invention, a filler is added to the liquid crystal polyester as needed. When adding filler,
Filler 150 per 100 parts by weight of liquid crystal polyester
Below 100 parts by weight, preferably 20 to 100 parts by weight of the filler is added to 100 parts by weight of the liquid crystal polyester. When the compounding ratio of the filler is more than 150 parts by weight, the melt viscosity of the composition becomes high, and the granulation property and moldability are deteriorated. However, the effect of stabilizing the plasticization during molding is reduced. The liquid crystal polyester resin composition used in the present invention is preferably in the form of particles such as pellets, chips or powder in order to facilitate mixing with the phosphorus compound and the like.

The filler used in the present invention is a fibrous or needle-shaped reinforcing material such as glass fiber, silica-alumina fiber, wollastonite, carbon fiber, potassium titanate whiskers, aluminum borate whiskers, titanium oxide whiskers and the like. Calcium carbonate, dolomite, talc,
Examples thereof include inorganic fillers such as mica, clay, and glass beads, and one or more of them can be used.

The higher fatty acid used as a raw material for the higher fatty acid ester used in the present invention has 10 or more carbon atoms. Examples of higher fatty acids include capric acid, lauric acid, myristic acid, valmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, montanic acid and the like. Of these, stearic acid and montanic acid are particularly preferable. Examples of alcohols used as the raw material for the ester include stearyl alcohol, behenyl alcohol, glycerin, sorbitan, propylene glycol, pentaerythritol, and polyoxyethylene bisphenol A. Of these, glycerin and sorbitan are preferable. The higher fatty acid ester used in the present invention preferably has a melting point of 30 ° C. or higher, more preferably 50 ° C. or higher. When a higher fatty acid ester having a melting point of less than 30 ° C. is used, a part of the higher fatty acid ester is volatilized when the liquid crystal polyester resin mixture is pre-dried before molding, and the effect of stabilizing plasticization at the intended molding process is reduced. To be done. The higher fatty acid ester used in the present invention preferably has a powder or particle shape in order to facilitate mixing with the liquid crystal polyester resin composition.

The higher fatty acid ester preferably has an average particle size of less than 100 μm, and a particle size of 5
It is more preferably less than 0 μm. Particle size is 100 μm
In the above cases, the effect of stabilizing plasticization during molding is insufficient, which is not preferable.

In the liquid crystal polyester resin mixture of the present invention, the blending ratio of the higher fatty acid ester is 0.001 to 5 parts by weight, relative to 100 parts by weight of the liquid crystal polyester, or 100 parts by weight of the liquid crystal polyester and the filler. A preferred blending ratio is 0.003 to 1 part by weight. When the blending ratio of the higher fatty acid ester is more than 5 parts by weight, a gas caused by the decomposition of the phosphorus compound is generated during the molding process, the molded product is likely to swell, and the generated gas from the molded product is increased. Therefore, it is not preferable. Further, when the blending ratio of the higher fatty acid ester is less than 0.001 part by weight, the effect of stabilizing the intended plasticization during molding is insufficient, which is not preferable.

In the liquid crystal polyester resin mixture of the present invention, higher fatty acid, at least one compound selected from oxides, peroxides, double oxides, and carbonates of metals belonging to Group 1A or 2A, higher fatty acid metal It is also possible to mix a salt, a phosphorus compound, a fluororesin, a fluorocarbon-based surfactant or the like having an external lubricant effect with the higher fatty acid ester in the liquid crystal polyester resin composition. In addition, to the liquid crystal polyester resin composition or the liquid crystal polyester resin mixture of the present invention used in the present invention, a coloring agent such as a dye or a pigment; an antioxidant; a heat stabilizer; Absorbent;
One or more kinds of usual additives such as an antistatic agent and a surfactant can be added. Further, a small amount of thermoplastic resin, for example, polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether and its modified products, polysulfone, polyether sulfone, polyetherimide and the like, a small amount of thermosetting resin, For example, one kind or two or more kinds of phenol resin, epoxy resin, polyimide resin, etc. can be added.

The liquid crystal polyester resin mixture of the present invention is
The compounding means is not particularly limited as long as a liquid crystal polyester or a liquid crystal polyester resin composition containing a liquid crystal polyester and a filler as a main component and a mixture of a higher fatty acid ester are mixed below the flow temperature of the liquid crystal polyester. For example, it can be obtained by mixing particles of a liquid crystal polyester resin composition and powder or particles of a mixture with a higher fatty acid ester in a solid state at room temperature or in a warm atmosphere using a Henschel mixer, a tumbler or the like.

The compounding means for obtaining the liquid crystal polyester or the liquid crystal polyester resin composition containing the liquid crystal polyester and the filler as the main components is not particularly limited. It is preferable that the liquid crystal polyester, the filler, and, if necessary, the release improver, the heat stabilizer, the colorant, and the like be mixed using a Henschel mixer, a tumbler, or the like, and then melt-kneaded using an extruder.

[0026]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. The measurements and tests of various physical properties in the examples were performed by the following methods. (1) Measuring property during injection molding: The average measuring time of 50 consecutive shots and its standard deviation were calculated. (2) Tensile physical properties: ASTM No. 4 tensile dumbbells are molded,
It was measured in accordance with ASTM D638.

(3) Relative amount of low boiling point gas generated from the molded product: JIS 1 (1/2) dumbbell (thickness 0.8 m
m), and the resulting molded product has a length of 5 mm and a width of 5 m.
m, and the thickness was 0.8 mm. This chip 4
g is precisely weighed, washed with distilled water, put in a vacuum-dried 25 cc vial, sealed with packing made of polytetrafluoroethylene, heated in a hot air dryer set at 120 ° C for 20 hours, and molded. Gas was generated from the product. This vial was used as a headspace gas chromatograph (GC-15A / HSS-3 manufactured by Shimadzu Corporation).
Attached to A) and keeping it at 120 ° C, DB as a filler
-WAX (manufactured by J & WSCIENTIFIC) was injected into a 15-m long column, the column temperature was raised from 80 ° C to 2 ° C / min simultaneously with the injection, and the total amount of gas up to a retention time of 25 minutes was detected by a detector. . An FID type was used as the detector, and helium was used as the carrier gas.

The relative amount of this gas is expressed by the total area of various gases, and the relative amount of gas generated from the molded article was compared with this value. If you did not put the sample in the vial,
That is, the measured value in an empty bottle is 3000, and the larger this value is, the more the low boiling point gas is generated from the molded product. Further, the gas detected by the retention time of 25 minutes was determined by gas chromatography-mass spectrometry to be an aromatic hydrocarbon,
It was confirmed to be aliphatic hydrocarbons, acetic acid, phenols and the like.

Examples 1 to 4, Comparative Examples 1 to 3 The repeating structural unit is the above A.₁, B₁, B_Two, C₁From
A₁: B₁: B _Two: C₁Is a molar ratio of 60:15:
5:20 and the flow temperature defined above is 323 ° C.
Liquid crystal polyester and milled glass fiber
Table 1 shows EFH75-01 manufactured by Tral Glass Co., Ltd.
After mixing with a Henschel mixer, the twin screw extruder (Ikegai Tetsu
Cylinder temperature using PCM-30 type manufactured by Kou Co., Ltd.
Granulation at 340 ° C. to obtain a liquid crystal polyester resin composition
Was. The obtained liquid crystal polyester resin composition is a high-grade fat
With acid ester (stearic acid monodiglyceride)
In a tumbler at a ratio shown in Table 1 at room temperature,
A liquid crystal polyester resin mixture was obtained.

These liquid crystal polyester resin mixtures were dried at the temperatures shown in Table 1 for 3 hours, and then, using an injection molding machine (PS40E5ASE manufactured by Nissei Jushi Kogyo Co., Ltd.), the cylinder temperature was 350 ° C. and the mold temperature was 130 ° C. (1/2)
No. dumbbell was molded, the weighing time of 50 consecutive shots was measured, and its stability was evaluated. The tensile properties and the amount of generated gas were measured from the obtained dumbbell pieces. Similarly, the liquid crystal polyester resin composition containing no higher fatty acid ester (Comparative Example 1) was measured for stability in measuring time, tensile properties, and amount of generated gas. Table 1 shows the results.

The higher fatty acid ester mixed with the liquid crystal polyester resin composition (Examples 1 to 4) showed less fluctuation in the measuring time between shots than the composition containing no higher fatty acid ester (Comparative Example 1). It can be seen that the measuring time itself is shortened, the resin is stably plasticized, has excellent mechanical properties, and the gas generated from the molded product is at a low level. Further, the one obtained by mixing 0.0005 parts by weight of the higher fatty acid ester with the liquid crystal polyester resin composition (Comparative Example 2) had an insufficient effect of stable plasticization during molding. On the other hand, in the case of mixing 10 parts by weight of the higher fatty acid ester with the liquid crystal polyester resin composition (Comparative Example 3), discoloration was observed in the molded product and the tensile properties were significantly lowered, and the gas generated from the molded product was observed. The amount was remarkably large.

Comparative Example 4 An experiment was carried out in the same manner as in Example 1 except that the higher fatty acid ester was mixed with the liquid crystal polyester in advance together with the milled glass fiber and granulated with a twin-screw extruder. Table 1 shows the results. The higher fatty acid ester previously kneaded in a liquid crystalline polyester resin in a molten state (Comparative Example 4) is
Both the absolute value of the measuring time and the variation between shots were large, and the plasticization during molding was unstable.

Examples 5 to 7 Nos. Shown in Table 2 as higher fatty acid esters. 2-No.
An experiment was conducted in the same manner as in Example 1 except that 4 was used. Table 1 shows the results. No. 2-No. The liquid crystal polyester resin composition containing the higher fatty acid ester of No. 4 (Examples 5 to 7) also has a small variation in shot time between shots as in the case of blending stearic acid monodiglyceride, and the measurement time itself. It can be seen that the length is shortened, the resin is stably plasticized, has excellent mechanical properties, and the gas generated from the molded product is at a low level.

Comparative Example 5 An experiment was conducted in the same manner as in Example 1 except that stearic acid, which is a higher fatty acid, was used instead of the higher fatty acid ester. Table 1 shows the results. The liquid crystal polyester resin mixture mixed with stearic acid (Comparative Example 5) had a large absolute value of the measuring time and a large variation between shots in the molding after predrying at 150 ° C., and the plasticization was unstable during the molding process. Met.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

EFFECT OF THE INVENTION The liquid crystal polyester resin mixture of the present invention is a molded product in which the liquid crystal polyester is stably plasticized at the time of molding, stable molding can be performed, and mechanical properties and thermal stability are excellent. Is a liquid crystalline polyester resin mixture to give. The liquid crystal polyester molding method using the liquid crystal polyester resin mixture is useful in molding such as injection molding and extrusion molding performed using an extruder using a screw.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Nagano 6 Kitahara, Tsukuba, Ibaraki Prefecture Sumitomo Chemical Co., Ltd.

Claims (3)

[Claims] 1. A liquid polyester 100 parts by weight and a filler 0
To 150 parts by weight of a liquid crystal polyester resin composition as a main component and higher fatty acid ester 0.001
A liquid crystal polyester resin mixture, characterized in that ˜5 parts by weight are mixed below the flow temperature of the liquid crystal polyester resin composition measured by the following method. Flowing temperature: Resin heated at a temperature rising rate of 4 ° C./min under a load of 100 kgf / cm ² , inner diameter 1 mm, length 10
When extruded from mm nozzle, melt viscosity is 48000
It is the temperature that indicates poise. 2. The liquid crystal polyester resin mixture according to claim 1, wherein the liquid crystal polyester contains at least 30 mol% of repeating structural units represented by the following formula A ₁ . Embedded image 3. A method for molding a liquid crystal polyester, which comprises using the liquid crystal polyester resin mixture according to claim 1 or 2.