JP2012030476A - Method for manufacturing crystal liquid polyester molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of capable of manufacturing a liquid crystal molded article excellent in surface smoothness in low specific gravity.SOLUTION: The liquid crystal polyester molded article is manufactured by injection-molding the crystal polyester composition comprising a hollow body of 15-35 pts.pass compound having a volume average grain diameter of 15-30 μm with respect to liquid crystal polyester of 100 pts.pass at 140°C or higher of a mold temperature. The hollow body is preferably a glass balloon and the compression strength of the hollow body is preferably 60 MPa or higher.

Description

  The present invention relates to a method for producing a liquid crystal polyester molded body.

  Since liquid crystalline polyester has high heat resistance and excellent moldability, it is used as a molding material for manufacturing various products and parts such as machine parts, home appliance parts, communication equipment parts, OA parts, and automobile parts. . In recent years, these products and parts are often required to be lightweight, that is, have a low specific gravity, and various liquid crystal polyester compositions obtained by blending a liquid crystal polyester with a hollow body have been studied as molding materials. In addition, the molding is often performed by injection molding because of its high degree of freedom in shape. For example, Patent Documents 1 to 3 describe a liquid crystal polyester composition in which a hollow body is blended with a liquid crystal polyester. It describes that injection molding is performed at a mold temperature of 130 ° C.

JP 2001-172479 A JP 2001-310323 A JP 2009-114418 A

  In the methods described in Patent Documents 1 to 3, the liquid crystal polyester molded body obtained may be inferior in surface smoothness because the hollow body is easily exposed on the surface, for example, when it comes into contact with other members May hurt it. Accordingly, an object of the present invention is to provide a method capable of producing a liquid crystal polyester molded article having a low specific gravity and excellent surface smoothness.

  In order to achieve the above object, the present invention provides a liquid crystal polyester composition in which a hollow body having a volume average particle size of 15 to 30 μm and 15 to 35 parts by mass is blended with 100 parts by mass of a liquid crystal polyester. The manufacturing method of the liquid crystalline polyester molded object which carries out injection molding by the above is provided.

  According to the present invention, a liquid crystal polyester molded article having a low specific gravity and excellent surface smoothness can be obtained.

  The liquid crystalline polyester is a liquid crystalline polyester that exhibits liquid crystallinity in a molten state, and is preferably melted at a temperature of 450 ° C. or lower. The liquid crystal polyester may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide. The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester using only an aromatic compound as a raw material monomer.

  A typical example of the liquid crystal polyester is obtained by polymerizing (polycondensing) an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and a compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine. One obtained by polymerizing a plurality of types of aromatic hydroxycarboxylic acids, one obtained by polymerizing an aromatic dicarboxylic acid and a compound selected from the group consisting of aromatic diols, aromatic hydroxyamines and aromatic diamines, and Examples include those obtained by polymerizing a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid. Here, instead of part or all of the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine and aromatic diamine, a polycondensable derivative thereof may be used.

  Examples of polycondensable derivatives of compounds having a carboxyl group such as aromatic hydroxycarboxylic acid and aromatic dicarboxylic acid include those obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group, Those obtained by converting into a haloformyl group and those obtained by converting a carboxyl group into an acyloxycarbonyl group can be mentioned. Examples of polycondensable derivatives of compounds having a hydroxyl group such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines include those obtained by acylating a hydroxyl group and converting it to an acyloxyl group. It is done. Examples of the polycondensable derivative of a compound having an amino group such as aromatic hydroxyamine and aromatic diamine include those obtained by acylating an amino group and converting it to an acylamino group.

  The liquid crystalline polyester preferably has a repeating unit represented by the following formula (1) (hereinafter sometimes referred to as “repeating unit (1)”), and is further represented by the following formula (2). Repeating units (hereinafter sometimes referred to as “repeating units (2)”) and repeating units represented by the following formula (3) (hereinafter also referred to as “repeating units (3)”). It is more preferable to have it.

(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-

(Ar ¹ represents a phenylene group, a naphthylene group, or a biphenylylene group. Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4). X And Y each independently represents an oxygen atom or an imino group (—NH—), and each hydrogen atom in the group represented by Ar ¹ , Ar ² or Ar ³ independently represents a halogen atom or an alkyl group. Alternatively, it may be substituted with an aryl group.)

(4) -Ar ⁴ -Z-Ar ^5-

(Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)

  Here, examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group and 2-ethylhexyl group. Is usually 1-10. Examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group, and the number of carbon atoms is usually 6-20. Examples of the alkylidene group include a methylene group, an ethylidene group, an isopropylidene group, an n-butylidene group, and a 2-ethylhexylidene group, and the number of carbon atoms is usually 1-10.

The repeating unit (1) is a repeating unit derived from an aromatic hydroxycarboxylic acid, and Ar ¹ includes a p-phenylene group (derived from p-hydroxybenzoic acid) and a 2,6-naphthylene group (6-hydroxy- 2) derived from 2-naphthoic acid.

The repeating unit (2) is a repeating unit derived from an aromatic dicarboxylic acid, and Ar ² includes a p-phenylene group (derived from terephthalic acid), an m-phenylene group (derived from isophthalic acid), and 2,6- A naphthylene group (derived from 6-hydroxy-2-naphthoic acid) is preferred.

The repeating unit (3) is a repeating unit derived from aromatic diol, aromatic hydroxylamine or aromatic diamine, and Ar ³ is derived from p-phenylene group (hydroquinone, p-aminophenol or p-phenylenediamine). And 4,4′-biphenylylene groups (derived from 4,4′-dihydroxybiphenyl, 4-amino-4′-hydroxybiphenyl or 4,4′-diaminobiphenyl).

  The content of the repeating unit (1) is the total amount of all repeating units constituting the liquid crystalline polyester (the amount of each repeating unit by dividing the mass of each repeating unit constituting the liquid crystalline polyester by the formula weight of each repeating unit). It is preferably 30 mol% or more, more preferably 30 to 80 mol%, still more preferably 40 to 70 mol%, with respect to the equivalent amount (mol) obtained, and the sum of them. The higher the content of the repeating unit (1), the easier the liquid crystal polyester to improve the liquid crystallinity. However, if the content is too high, the melting temperature of the liquid crystal polyester becomes high and molding becomes difficult.

  The content of the repeating unit (2) is preferably 35 mol% or less, more preferably 10 to 35 mol%, still more preferably 15 to 15%, based on the total amount of all repeating units constituting the liquid crystal polyester. 30 mol%.

  The content of the repeating unit (3) is preferably 35 mol% or less, more preferably 10 to 35 mol%, still more preferably 15 to 15%, based on the total amount of all repeating units constituting the liquid crystal polyester. 30 mol%.

  The content ratio of the repeating unit (2) and the repeating unit (3) is expressed as [Repeating unit (2)] / [Repeating unit (3)] (mol / mol), 0.9 / 1 to 1/0. .9 is preferable because the molecular weight of the liquid crystal polyester tends to be high, and the heat resistance and strength of the liquid crystal polyester are easily improved.

  The repeating unit (3) is preferably such that X and Y are each an oxygen atom, that is, a repeating unit derived from an aromatic diol, because the viscosity at the time of melting of the liquid crystalline polyester tends to be low.

  The liquid crystal polyester is preferably produced by melt polymerization of raw material monomers and solid-phase polymerization of the obtained polymer (prepolymer). Thereby, high molecular weight liquid crystal polyester with high heat resistance and strength can be produced with good operability. The melt polymerization may be carried out in the presence of a catalyst. Examples of the catalyst include magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide. And nitrogen-containing heterocyclic compounds such as N, N-dimethylaminopyridine and N-methylimidazole, and nitrogen-containing heterocyclic compounds are preferably used.

  The liquid crystal polyester preferably has a flow start temperature of 270 to 400 ° C, more preferably 300 to 380 ° C. The higher the flow start temperature of the liquid crystalline polyester, the easier it is to improve the heat resistance and strength of the liquid crystalline polyester. However, if it is too high, the melting temperature of the liquid crystalline polyester will be high and molding will be difficult.

The flow start temperature is also called flow temperature or flow temperature, and is 4 ° C / min under a load of 9.8 MPa (100 kg / cm ² ) using a capillary rheometer having a nozzle having an inner diameter of 1 mm and a length of 10 mm. This is a temperature at which the melt viscosity shows 4800 Pa · s (48,000 poise) when the heated melt of liquid crystal polyester is extruded from the nozzle at a temperature rising rate, and is a measure of the molecular weight of the liquid crystal polyester (Naoyuki Koide) Ed., “Liquid Crystal Polymer—Synthesis / Molding / Application—”, CMC, June 5, 1987, p. 95).

  In the present invention, a liquid crystal polyester composition obtained by blending a hollow body with the liquid crystal polyester as described above is used as a molding material.

  The hollow body is also called a balloon, and examples of the material thereof include inorganic materials such as alumina, silica, magnesia, and shirasu, and organic materials such as urea resin and phenol resin. May be used in combination. Of these, glass is preferable from the viewpoint of heat resistance and strength, and therefore, the hollow body is preferably a glass balloon.

  The surface of the glass balloon is pretreated with a silane coupling agent such as amino silane, ureido silane, or epoxy silane in order to improve the compatibility with the liquid crystal polyester, and a functional group having an affinity for the liquid crystal polyester is provided. Also good.

  The particle diameter of the hollow body is 15 to 30 μm, preferably 15 to 25 μm, expressed as a volume average value from the viewpoint of the surface smoothness of the molded body. If the particle size of the hollow body is too small, the reduction in the specific gravity of the molded body becomes insufficient due to the high specific gravity of the hollow body. On the other hand, if the particle size of the hollow body is too large, the volume of the hollow body exposed on the surface of the molded body is increased, the surface smoothness is impaired, and the mating member that comes into contact is easily damaged. The volume average particle diameter of the hollow body can be measured by a laser diffraction method.

  The compounding quantity of a hollow body is 15-35 mass parts with respect to 100 mass parts of liquid crystalline polyester. If the amount of the hollow body is too small, the effect of weight reduction is small, and if the amount of the hollow body is too large, the volume of the hollow body exposed on the surface of the molded body increases, the surface smoothness is impaired, and contact is made. The mating member is easily damaged. In addition, the viscosity of the liquid crystal polyester composition is likely to increase during injection molding, making it difficult to produce micro-molded products and thin-walled large-sized products.

  The pressure resistance of the hollow body is preferably 60 MPa or more. The higher the pressure strength, the higher shear kneading using a screw with a high meshing rate, the high pressure of 60 MPa or more as a peak pressure, the high pressure and high speed injection molding for producing a high-sheared micro-molded product and thin-walled large molded product, There is little damage to the hollow body, which is preferable. The compressive strength of a hollow body can be measured by the glycerol method. Specifically, a certain amount of glass balloon and glycerol are mixed, sealed to prevent air from entering, and the volume change when pressurized is observed. Then, the pressure when the breakage rate exceeds 10% can be obtained as the pressure strength.

  Examples of commercially available hollow bodies include “S60HS” and “iM30K” from Sumitomo 3M Limited and “60P18” from Potters Barotini.

  A liquid crystal polyester composition is manufactured by mixing liquid crystal polyester, a hollow body, and fillers and additives used as necessary using a Henschel mixer, a tumbler, etc., and then melt-kneading using an extruder. Is preferable, and pelletization may be performed by this melt-kneading.

  In the present invention, the liquid crystal polyester composition thus obtained is injection-molded at a mold temperature of 140 ° C. or higher. Thereby, the molded object which is low specific gravity and is excellent in surface smoothness can be obtained. If the mold temperature is too high, the liquid crystal polyester tends to stick to the mold, so that it is preferably 180 ° C. ≧.

The liquid crystal polyester molded body thus obtained has low specific gravity, excellent surface smoothness, and excellent heat insulation. The liquid crystal polyester molded body preferably has a specific gravity of 1 to 1.3 g / cm ³ , and the surface roughness is preferably 2 to 9 μm in terms of ten-point average roughness Rz.

  Examples of products / parts obtained as a liquid crystal polyester molded body include machine parts, home appliance parts, communication equipment parts, OA parts, automobile parts, optical parts, board parts, and sliding parts.

Examples 1-6, Comparative Examples 1-4
[Liquid crystal polyester]
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser, p-hydroxybenzoic acid 621 g (4.5 mol), 4,4′-dihydroxybiphenyl 279 g (1.5 mol) ), 149.4 g (0.9 mol) of terephthalic acid, 99.6 g (0.6 mol) of isophthalic acid, and 841.5 g (8.25 mol) of acetic anhydride, and the inside of the reactor is sufficiently replaced with nitrogen gas. Then, the temperature was raised to 150 ° C. over 30 minutes under a nitrogen gas stream, and this temperature was maintained and refluxed for 30 minutes. Thereafter, the temperature was raised to 315 ° C. over 3 hours and 30 minutes while distilling off by-product acetic acid and unreacted acetic anhydride, and when an increase in torque was observed, the contents were taken out and cooled to room temperature. did. The obtained solid was pulverized with a coarse pulverizer, heated from room temperature to 230 ° C. over 1 hour in a nitrogen atmosphere, then heated from 230 ° C. to 250 ° C. over 50 minutes, and then at 250 ° C. By maintaining for 10 hours, solid phase polymerization was performed to obtain a liquid crystal polyester.

[Hollow body]
The following was used as the hollow body.
Hollow body (1): “110P8” from Potters Ballotini Co., Ltd. (material: glass, volume average particle size: 12 μm, pressure strength: 69 MPa)
Hollow body (2): “S60HS” manufactured by Sumitomo 3M Limited (material: glass, volume average particle size: 30 μm, pressure strength: 124 MPa)
Hollow body (3): “K46” manufactured by Sumitomo 3M Limited (material: glass, volume average particle size: 40 μm, pressure strength: 41 MPa)

[Liquid crystal polyester composition]
After blending the hollow body shown in Table 1 in the amount shown in Table 1 with respect to 100 parts by mass of the liquid crystalline polyester, using the same direction twin screw extruder ("PCM-30" by Ikekai Tekko Co., Ltd.), 340 It knead | mixed at 0 degreeC and pelletized, and liquid crystal polyester was obtained.

[Liquid crystal polyester molding]
The obtained liquid crystal polyester composition was injection-molded at the mold temperature shown in Table 1 to obtain ASTM No. 4 dumbbell (thickness 2.5 mm). The specific gravity of this ASTM No. 4 dumbbell was measured in accordance with ASTM D792 (23 ° C.), and the results are shown in Table 1. The same results were obtained when a test piece of 64 mm × 64 mm × thickness 15 mm, a length 127 mm, a width of 12.7 mm, and a thickness of 6.4 mm was used in place of the ASTM No. 4 dumbbell.

  Further, the obtained liquid crystal polyester composition was injection-molded at a mold temperature shown in Table 1 using a mold having a ten-point average roughness Rz of 1.5 μm, and a test piece having a thickness of 64 × 64 × 3 mm Got. The ten-point average roughness Rz of this test piece was measured according to JIS B0601-1994, and the results are shown in Table 1.

Claims (6)

  Manufacture of a liquid crystal polyester molded body in which a liquid crystal polyester composition comprising 15 to 35 parts by mass of a hollow body having a volume average particle size of 15 to 30 μm is blended with 100 parts by mass of liquid crystal polyester at a mold temperature of 140 ° C. or more Method. The liquid crystalline polyester is a liquid crystalline polyester having a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a repeating unit represented by the following formula (3). The liquid composition according to 1.
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(Ar ¹ represents a phenylene group, a naphthylene group, or a biphenylylene group. Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4). X And Y each independently represents an oxygen atom or an imino group, and each hydrogen atom in the group represented by Ar ¹ , Ar ² or Ar ³ is independently substituted with a halogen atom, an alkyl group or an aryl group. May be.)
(4) -Ar ⁴ -Z-Ar ^5-
(Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.)   The liquid crystal polyester has a repeating unit represented by the formula (1) of 30 to 80 mol% and a repeating unit represented by the formula (2) of 10 with respect to the total amount of all repeating units constituting the liquid crystalline polyester. The liquid composition according to claim 2, which is a liquid crystal polyester having about 35 mol% and 10 to 35 mol% of the repeating unit represented by the formula (3). Ar ¹ is a p-phenylene group or a 2,6-naphthylene group, Ar ² is a p-phenylene group, an m-phenylene group or a 2,6-naphthylene group, and Ar ³ is a p-phenylene group or The liquid composition according to claim 2 or 3, which is a 4,4'-biphenylylene group, and X and Y are each an oxygen atom.   The said hollow body is a glass balloon, The manufacturing method of the liquid crystalline polyester molded object in any one of Claims 1-4.   The pressure-resistant strength of the hollow body is 60 MPa or more. The method for producing a liquid crystal polyester molded body according to any one of claims 1 to 5.