JP2007154169A - Liquid crystal polyester resin composition and molded product for electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molded product having excellent high-frequency characteristics and to provide a liquid crystal polyester resin composition for affording the molded product. <P>SOLUTION: The liquid crystal polyester resin composition comprises a component (a) composed of structural units represented by formulas (i), (ii) and (iii) (wherein, the content of an aromatic group having a 2,6-naphthalenediyl group is ≥70 mol% when the sum total of bifunctional aromatic groups represented by Ar<SB>1</SB>, Ar<SB>2</SB>and Ar<SB>3</SB>is 100 mol%) and (b) hollow particles. The molded product is obtained by molding the liquid crystal polyester resin composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a molded article having excellent high-frequency characteristics and a liquid crystal polyester resin composition capable of molding the molded article.

With the advancement of the advanced information society, in order to realize high-speed information processing and large-capacity information communication, the frequency band used by information communication electronic devices is increasingly shifting to a high frequency band. However, high frequency has the property of being lost by being converted to heat (dielectric loss), and as a measure to improve it, materials used for the above-mentioned equipment are required to be compatible with low dielectric constant and low dielectric loss tangent. Therefore, the need for resin materials is particularly high.

As resin materials having a low dielectric constant, fluororesins and polyolefin resins are known. However, these materials are insufficient from the viewpoint of heat resistance, moldability or mechanical properties, and are among the information communication electronic devices. Therefore, it is difficult to use as a member of equipment that requires miniaturization and high density. Therefore, development of a resin material capable of obtaining a member (molded product) having high heat resistance and mechanical characteristics in addition to excellent high frequency characteristics such as low dielectric constant and low dielectric loss tangent has been eagerly desired.

As described above, liquid crystal polyester has attracted attention among resin materials from the viewpoint of miniaturization and high density. Since liquid crystalline polyester is excellent in processability, it can meet the needs for miniaturization and high density as a molding material capable of precision molding. Liquid crystal polyester resin molded products aiming at improving high-frequency characteristics by taking advantage of such excellent workability have been studied.

As an example, for example, Patent Document 1 proposes a liquid crystal polyester resin composition containing liquid crystal polyester, an inorganic spherical hollow body, and an inorganic filler having an aspect ratio of 4 or more, and is obtained from the liquid crystal polyester resin composition. It is disclosed that a molded product having a specific dielectric constant of 3 or less can be obtained and an excellent hue after heat treatment can be obtained by reducing the apparent specific gravity by blending an inorganic spherical hollow body.
JP-A-2004-27021 (Claims, paragraph [0021], Examples)

However, even in a molded product obtained from the liquid crystal polyester resin composition disclosed in Patent Document 1, it cannot be said that the dielectric loss tangent is sufficiently low, and it is used for a member of a device related to a future high frequency band region. It was difficult. Since the dielectric loss increases in proportion to the square root of the dielectric constant and the dielectric loss tangent, it is important to lower the dielectric loss tangent rather than the dielectric constant. An object of the present invention is to provide a liquid crystal polyester resin composition for obtaining a molded article having both a low dielectric constant and a low dielectric loss tangent, particularly excellent low dielectric loss tangent, and obtained by molding the liquid crystal polyester resin composition. The present invention provides a molded article suitable as a member for future information communication electronic equipment.

（式中、Ａｒ₁は、２,６−ナフタレンジイル基、１，４−フェニレン基及び４，４’−ビフェニリレン基からなる群から選ばれる芳香族基である。Ａｒ₂、Ａｒ₃は、それぞれ独立に、２,６−ナフタレンジイル基、１，４−フェニレン基、１，３−フェニレン基及び４，４’−ビフェニリレン基からなる群から選ばれる芳香族基である。また、Ａｒ₁、Ａｒ₂、Ａｒ₃で示される芳香族基は、該芳香族基にある芳香環の水素原子の一部又は全部が、ハロゲン原子、炭素数１〜１０のアルキル基又はアリール基で置換されていてもよい。） As a result of intensive studies to realize a low dielectric loss tangent of a molded product obtained from a liquid crystal polyester and a liquid crystal polyester resin composition containing hollow particles, the present inventors have used a liquid crystal polyester having a specific aromatic group. The inventors have found that a molded article having excellent high-frequency characteristics, heat resistance and mechanical characteristics can be obtained without impairing moldability, and the present invention has been completed based on this finding.
That is, the present invention
Component (a): consisting of structural units represented by the following (i), (ii) and (iii), the total of the divalent aromatic groups represented by Ar ₁ , Ar ₂ and Ar ₃ being 100 mol %, A liquid crystal polyester having an aromatic group having a 2,6-naphthalenediyl group of 70 mol% or more and a component (b); a liquid crystal polyester resin composition containing hollow particles is provided.

(In the formula, Ar ₁ is an aromatic group selected from the group consisting of 2,6-naphthalenediyl group, 1,4-phenylene group, and 4,4′-biphenylylene group. Ar ₂ and Ar ₃ are respectively independently, 2,6-naphthalene-diyl group, a 1,4-phenylene group, an aromatic group selected from the group consisting of 1,3-phenylene group and 4,4'-biphenylene group. Furthermore, Ar _1, Ar ₂ , the aromatic group represented by Ar ₃ , even if some or all of the hydrogen atoms of the aromatic ring in the aromatic group are substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group Good.)

Here, the “aromatic group having a 2,6-naphthalenediyl group” means a 2,6-naphthalenediyl group and a part or all of the hydrogen atoms of the naphthalene ring in the 2,6-naphthalenediyl group are halogen. It is a concept including an aromatic group substituted by an atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group.

The hollow particles are preferably made of a material having a high mechanical strength from the viewpoint of suppressing the destruction of the hollow particles themselves at the time of molding. Specifically, the hollow particles are preferably hollow particles made of glass, that is, glass balloons.

Furthermore, the liquid crystal polyester resin composition of the present invention is preferably such that the component (a) is 40 to 80% by weight when the total of the component (a) and the component (b) is 100% by weight.

Moreover, the liquid crystal polyester resin composition of this invention can also mix 30 weight% or less of a component (c) inorganic filler with respect to the weight of a component (a). Thus, by mixing a component (c), since this liquid crystalline polyester resin composition is more excellent in a moldability, it is preferable and as this inorganic filler, glass fiber is preferable.

The present invention also provides a molded article comprising a liquid crystal polyester resin composition containing the component (a) and the component (b), and optionally containing the component (c) inorganic filler. . The molded article can provide a molded article having a relative dielectric constant of 3.0 or less at a measurement temperature of 23 ° C. and a frequency of 1 MHz, and a dielectric loss tangent of 10 × 10 ⁻³ or less.

The molded product obtained from the liquid crystal polyester resin composition of the present invention is excellent in high-frequency characteristics such as low dielectric constant and low dielectric loss tangent, and is particularly useful for members related to information communication electronic devices.

Hereinafter, preferred embodiments of the present invention will be described.

（式中、Ａｒ₁は、２,６−ナフタレンジイル基、１，４−フェニレン基及び４，４’−ビフェニリレン基からなる群から選ばれる芳香族基である。Ａｒ₂、Ａｒ₃は、それぞれ独立に、２,６−ナフタレンジイル基、１，４−フェニレン基、１，３−フェニレン基及び４，４’−ビフェニリレン基からなる群から選ばれる芳香族基である。また、Ａｒ₁、Ａｒ₂、Ａｒ₃で示される芳香族基は、該芳香族基にある芳香環の水素原子の一部又は全部が、ハロゲン原子、炭素数１〜１０のアルキル基又はアリール基で置換されていてもよい。） <Liquid crystal polyester>
The liquid crystal polyester applied as the component (a) in the liquid crystal polyester resin composition of the present invention is a polyester that exhibits optical anisotropy at the time of melting and forms an anisotropic melt at a temperature of 450 ° C. or less. When the total of divalent aromatic groups represented by (i), (ii) and (iii) and represented by Ar ₁ , Ar ₂ and Ar ₃ is 100 mol%, It is a liquid crystal polyester in which the aromatic group having a 6-naphthalenediyl group is 70 mol% or more. Such a liquid crystal polyester has a structural unit having a 2,6-naphthalenediyl group in a liquid crystal polyester obtained by combining a monomer having a 2,6-naphthalenediyl group and another monomer at the stage of producing the liquid crystal polyester. It can be obtained by selecting and polymerizing raw material monomers so as to be in the above-mentioned range.

(In the formula, Ar ₁ is an aromatic group selected from the group consisting of 2,6-naphthalenediyl group, 1,4-phenylene group, and 4,4′-biphenylylene group. Ar ₂ and Ar ₃ are respectively independently, 2,6-naphthalene-diyl group, a 1,4-phenylene group, an aromatic group selected from the group consisting of 1,3-phenylene group and 4,4'-biphenylene group. Furthermore, Ar _1, Ar ₂ , the aromatic group represented by Ar ₃ , even if some or all of the hydrogen atoms of the aromatic ring in the aromatic group are substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group Good.)

The liquid crystalline polyester is preferably a wholly aromatic liquid crystalline polyester, that is, a structural unit constituting the liquid crystalline polyester that does not contain an aliphatic group such as an alkylene group. Since the wholly aromatic liquid crystalline polyester is excellent in heat resistance, it can be suitably used as the liquid crystalline polyester resin composition of the present invention. Here, the wholly aromatic polyester is a resin in which the divalent aromatic groups represented by Ar ₁ , Ar ₂ or Ar ₃ are linked by an ester bond (—C (O) O—). Yes, the proportion of the structural unit represented by (ii) and the proportion of the structural unit represented by (iii) in all the structural units constituting the resin are substantially equal.

Moreover, it is preferable that the structural unit derived from the aromatic hydroxycarboxylic acid represented by (i) constituting the liquid crystal polyester is 30 to 80 mol% with respect to the total of all the structural units. When the structural unit represented by (i) is in this range, the liquid crystal polyester can be sufficiently developed and the melt processability can be further improved.
Furthermore, the structural unit derived from the aromatic hydroxycarboxylic acid represented by the formula (i) is more preferably 40 to 70 mol%, and particularly preferably 45 to 65 mol%.

On the other hand, for the same reason as the preferable content of the structural unit represented by (i), the structural unit derived from the aromatic dicarboxylic acid represented by (ii) and the fragrance represented by (iii) The structural unit derived from the group diol is preferably 10 to 35 mol% independently of the total of all the structural units.
Furthermore, the structural unit represented by the above (ii) and the structural unit represented by the above (iii) are more preferably 15 to 30 mol% based on the total of all the structural units, respectively. It is especially preferable that it is -27.5 mol%.

Examples of the monomer that forms the structural unit represented by (i) include aromatic hydroxycarboxylic acids represented by 2-hydroxy-6-naphthoic acid, p-hydroxybenzoic acid, and 4- (4-hydroxyphenyl) benzoic acid. An acid can be used, and a monomer in which some or all of the hydrogen atoms of the aromatic ring in these monomers are substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group can also be used. Here, as a monomer which forms the structural unit containing an aromatic group having a 2,6-naphthalenediyl group of the present invention, it is 2-hydroxy-6-naphthoic acid, and further, 2-hydroxy-6-naphthoic acid. Mention may also be made of monomers in which the hydrogen atom of the naphthalene ring is substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group.
Furthermore, the aromatic hydroxycarboxylic acid may be used as an ester-forming derivative described later from the viewpoint of improving the reactivity when obtaining a liquid crystal polyester.

Examples of the monomer that forms the structural unit represented by the formula (ii) include aromatic dicarboxylic acids represented by naphthalene-2,6-dicarboxylic acid, terephthalic acid, isophthalic acid, or biphenyl-4,4′-dicarboxylic acid. Furthermore, a monomer in which some or all of the hydrogen atoms of the aromatic ring in these monomers are substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group can also be used. Here, as a monomer which forms the structural unit containing an aromatic group having a 2,6-naphthalenediyl group of the present invention, naphthalene-2,6-dicarboxylic acid is used, and further naphthalene-2,6-dicarboxylic acid is used. Mention may also be made of monomers in which the hydrogen atom of the naphthalene ring is substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group.
Furthermore, the aromatic dicarboxylic acid may be used as an ester-forming derivative described later from the viewpoint of improving the reactivity when obtaining a liquid crystal polyester.

Examples of the monomer that forms the structural unit represented by the formula (iii) include aromatic diols such as 2,6-naphthol, hydroquinone, resorcin, and 4,4′-dihydroxybiphenyl. A monomer in which some or all of the hydrogen atoms of a certain aromatic ring are substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group can also be used. Here, the monomer for forming the structural unit containing an aromatic group having a 2,6-naphthalenediyl group of the present invention is 2,6-naphthol, and the hydrogen atom of the naphthalene ring of 2,6-naphthol is And a monomer substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group.
Further, the aromatic diol may be used as an ester-forming derivative described later from the viewpoint of improving the reactivity when obtaining a liquid crystal polyester.

As described above, any of the structural units represented by (i), (ii) or (iii) may have a substituent on the aromatic ring (benzene ring or naphthalene ring), and these substituents As examples of the halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom can be given. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. An alkyl group represented by a group, an octyl group, a decyl group, etc., which may be linear or branched, or an alicyclic group. As an aryl group, a C6-C20 aryl group represented by a phenyl group, a naphthyl group, etc. is mentioned, for example.

As the monomer that forms the structural unit represented by (i), (ii), or (iii), an ester-forming derivative is preferably used in order to facilitate polymerization in the process of producing a polyester. The ester-forming derivative refers to a monomer having a group that promotes an ester formation reaction. Specifically, an ester obtained by converting a carboxylic acid group in a monomer molecule into an acyl halide group or an acid anhydride. Examples thereof include highly reactive derivatives such as ester-forming derivatives in which a phenolic hydroxyl group in the monomer molecule is converted to a lower carboxylic acid ester group.

As a method for producing the liquid crystal polyester, it can be produced by a known method. Particularly preferably, the ester-forming derivative is a derivative obtained by converting a phenolic hydroxyl group in a monomer molecule into a lower carboxylic acid ester group. An acyl group is particularly preferable as the lower carboxylic acid ester group. Acylation can usually be achieved by reacting a monomer having a phenolic hydroxyl group with acetic anhydride. These ester-forming derivatives by acylation can be polymerized by deacetic acid polycondensation, and polyesters can be easily produced.

More specifically, for example, a known method such as the method described in JP-A-2002-146003 can be applied. That is, the monomer that forms the structural unit represented by (i), (ii), and (iii) can be introduced into the liquid crystalline polyester as the structural unit containing an aromatic group having a 2,6-naphthalenediyl group. The monomer is selected so as to be 70 mol% or more based on the total of all monomers, and after conversion to an ester-forming derivative as necessary, melt polymerization is performed, and a relatively low molecular weight aromatic liquid crystal polyester (hereinafter, referred to as “polyester”). (Hereinafter abbreviated as “prepolymer”), followed by solid phase polymerization by heating the prepolymer as a powder. Use of such solid phase polymerization is preferable because the polymerization proceeds more and the molecular weight can be increased.

<Hollow particles>
The component (b) hollow particle used in the present invention is a filler having a hollow portion generally called a balloon as a lightweight functional filler. Examples of the material constituting the hollow particles include inorganic materials such as alumina, silica, and glass, and organic materials such as urea resin and phenol resin. If necessary, two or more kinds are mixed materials. Alternatively, two or more kinds of lightweight functional fillers may be used. As described above, these light-weight functional fillers can be easily obtained from the market and may be used. Examples of such lightweight functional filler include alumina bubble (registered trademark of Taiheiyo Random Co., Ltd.), scotch bubble (registered trademark of Sumitomo 3M Co., Ltd.), cell star (registered trademark of Tokai Kogyo Co., Ltd.), Potters Baro Examples thereof include hollow glass beads manufactured by Tini, Towanalite (registered trademark of Toyohada Nao Co., Ltd.), and Ecosphere (registered trademark of Emerson & Cumming). Among these, from the viewpoints of heat resistance and strength, the material constituting the hollow particles is preferably glass, and so-called glass balloons are preferably used.

The volume average particle size of the hollow particles used in the liquid crystal polyester resin composition of the present invention is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of moldability and mechanical strength. On the other hand, the upper limit of the volume average particle diameter of the hollow particles is preferably 500 μm or less, and more preferably 200 μm or less, from the viewpoint of suppression of fracture and moldability. Here, the volume average particle diameter is a volume average particle diameter determined by a volume particle diameter distribution determined by a laser diffraction method, and a suitable volume from a lightweight functional filler that can be easily obtained from the market exemplified above. Those having an average particle diameter may be selected, or those having a preferred volume average particle diameter can be selected using a known means for selecting a volume average particle diameter.
Moreover, the volumetric hollow ratio of the hollow particles used in the liquid crystal polyester resin composition of the present invention is preferably 40 to 80%, more preferably 60 to 80% or more. The volume hollowness can be estimated by the following formula.

(Volume hollow ratio) = 100 × {(1-σ ₁ ) / σ ₂ }

Here, σ ₁ represents the true specific gravity of the hollow particles, and σ ₂ represents the specific gravity of the material constituting the hollow particles.

Here, the compounding ratio of the component (a) and the component (b) is such that the component (a) is 40 to 80% by weight when the total of the component (a) and the component (b) is 100% by weight. The component (b) is preferably 60 to 20% by weight. Furthermore, the component (a) is more preferably 60 to 80% by weight, and the component (a) is particularly preferably 70 to 80% by weight. When the content weight ratio of the component (a) and the component (b) is in the above range, the breakage of the hollow particles at the time of molding is further suppressed, so that the obtained molded product has a high dielectric constant. Can be achieved.

<Other additives>
The liquid crystalline polyester of the present invention may contain a component (c) inorganic filler for the purpose of improving mechanical strength. Examples of the inorganic filler include glass fiber, asbestos fiber, silica fiber, asbestos fiber, and silica alumina fiber, and glass fiber is preferably used.

When the inorganic filler is blended, the blending ratio is preferably 30% by weight or less with respect to the weight of the component (a). When the blending ratio of the inorganic filler is within this range, the properties such as mechanical strength are improved without impairing the low dielectric constant and low dielectric loss tangent of the molded product obtained from the liquid crystal polyester resin composition of the present invention. be able to.

<Preparation method of liquid crystal polyester resin composition>
The method for preparing the liquid crystal polyester resin composition of the present invention can be produced by various conventional methods. In general, the component (a) and the component (b), and further, the component (c) may be mixed using a Henschel mixer, a tumbler or the like, if necessary. After heating and melting, the component (b) and, if necessary, the component (c) may be added and kneaded to form pellets. In addition, the component (a) and the component (b) and, if necessary, the component (c) are mixed in advance using a Henschel mixer, a tumbler, or the like to obtain a mixture. It is good also as a pellet by melt-kneading using.
It is preferable that the liquid crystalline polyester resin composition of the present invention is pelletized because it becomes easy to handle in a later molding method, and the component (a) and the component (b) are optionally added. Pellets obtained by premixing and then melt-kneading using an extruder are preferred.

<Molding method>
The molding method according to the liquid crystal polyester resin composition of the present invention is not particularly limited as long as it is a method that suppresses breakage of the hollow particle (b), which is an essential component. It can be molded into various shapes by various molding methods generally used in the field of thermoplastic resins, such as injection molding, extrusion molding, transfer molding, blow molding, press molding, injection press molding, extrusion injection molding. A plurality of these molding methods may be combined. A person skilled in the art can select a preferable molding method and molding conditions according to the shape of the target molded product.

<Molding>
By optimizing the combination of the liquid crystal polyester resin composition of the present invention and the molding method, the molded product obtained by molding the liquid crystal polyester resin composition has a relative dielectric constant of 3.0 or less and a dielectric loss tangent. A molded product of 10 × 10 ⁻³ or less can be obtained. Here, the relative dielectric constant and the dielectric loss tangent can be measured by a known method and is not particularly limited as long as measurement in a high frequency band region of 1 MHz or higher is possible. The dielectric loss tangent and relative dielectric constant are obtained from the impedance measurement using the method. An example of the measuring apparatus is HP4291A RF impedance / material analyzer manufactured by HP, and measurement is performed under conditions of a measurement temperature of 23 ° C. and a frequency of 1 MHz.

Molded products obtained by molding the liquid crystalline polyester resin composition of the present invention include connectors, sockets, relay parts, coil bobbins, optical pickups, oscillators, printed wiring boards, circuit boards, semiconductor packages, computer-related parts, etc.・ Electronic parts: IC tray, wafer carrier, etc. semiconductor manufacturing process related parts; VTR, TV, iron, air conditioner, stereo, vacuum cleaner, refrigerator, rice cooker, lighting equipment, etc .; household electrical product parts; lamp reflector, lamp Light fixture parts such as holders; Acoustic product parts such as compact discs, laser discs, speakers, etc .; Ferrules for optical cables, telephone parts, facsimile parts, communication equipment parts such as modems; Copying machines such as separation claws, heater holders, etc. Related parts: Impeller, fan gear, gear, shaft Mechanical parts such as receivers, motor parts and cases; automotive parts such as automotive parts, engine parts, parts in the engine room, electrical parts, interior parts, cooking utensils such as microwave cooking pans, heat-resistant dishes; Thermal insulation for flooring and wall materials, soundproofing materials, supporting materials such as beams and pillars, building materials such as roofing materials, or civil engineering and building materials; aircraft, spacecraft, space equipment parts; radiation facilities such as nuclear reactors Parts, marine facility parts, cleaning jigs, optical equipment parts, valves, pipes, nozzles, filters, membranes, medical equipment parts and medical materials, sensor parts, sanitary equipment, sports equipment, leisure goods and so on.
Moreover, since the liquid crystalline polyester resin composition of the present invention is excellent in extrusion moldability, it can be used as a coating material for resin molded products and metal parts, for example, for coating in various fields such as pipe coating and wire coating.
In addition, fibrous materials such as continuous fibers, short fibers, and pulp processed from the liquid crystal polyester resin composition of the present invention, and materials processed from them are industrially useful materials, such as clothing, heat-resistant heat insulating materials, It can be used for applications such as FRP reinforcing materials, rubber reinforcing materials, ropes, cables, and non-woven fabrics.
As described above, the molded product comprising the liquid crystal polyester resin composition of the present invention can be used for various applications. However, the molded product is excellent in high-frequency characteristics such as a low dielectric constant and a low dielectric loss tangent. It is particularly useful for members related to equipment.

Examples of the present invention will be described below, but the present invention is not limited thereto.

Production Example 1
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser, 987.95 g (5.25 mol) of 2-hydroxy-6-naphthoic acid, 4,4′-dihydroxybiphenyl 486 was added. .47 g (2.612 mol), 2,6-naphthalenedicarboxylic acid 513.45 g (2.375 mol), acetic anhydride 1174.04 (11.5 mol) and 1-methylimidazole 0.194 g as catalyst were added. After stirring for 15 minutes at room temperature, the temperature was raised with stirring. When the internal temperature reached 145 ° C., the mixture was stirred for 1 hour while maintaining the same temperature, and 5.83 g of 1-methylimidazole as a catalyst was further added.
Next, the temperature was raised from 145 ° C. to 310 ° C. over 3 hours and 30 minutes while distilling off distilling by-product acetic acid and unreacted acetic anhydride. A liquid crystal polyester was obtained by incubating at the same temperature for 2 hours. The obtained liquid crystal polyester was cooled to room temperature and pulverized with a pulverizer to obtain liquid crystal polyester powder (particle size: about 0.1 mm to about 1 mm).
It was 273 degreeC when the flow start temperature was measured about this powder (liquid crystalline polyester) using the flow tester.
The obtained powder was heated from 25 ° C. to 250 ° C. over 1 hour, then heated from the same temperature to 300 ° C. over 10 hours, and then kept at that temperature for 12 hours for solid phase polymerization. Thereafter, the powder after solid-phase polymerization was cooled to obtain a liquid crystal polyester. Let this liquid crystal polyester be A. About A, when the flow start temperature was measured using the flow tester, it was 326 degreeC. This is designated as liquid crystal polyester 1 (the ratio of 2,6-naphthalenediyl group to the total of all aromatic groups; 74.5 mol%).

Production Example 2
In the same reactor as in Production Example 1, 1023.499 g (5.5 mol) of 2-hydroxy-6-naphthoic acid, 272.52 g (2.475 mol) of hydroquinone, and 378.33 g of 2,6-naphthalenedicarboxylic acid ( 1.75 mol), 83.07 g (0.5 mol) of terephthalic acid, 1226.87 (11.9 mol) of acetic anhydride and 0.17 g of 1-methylimidazole as a catalyst were added and stirred at room temperature for 15 minutes. The temperature was increased while stirring. When the internal temperature reached 145 ° C., the mixture was stirred for 1 hour while maintaining the same temperature.
Next, the temperature was raised from 145 ° C. to 310 ° C. over 3 hours and 30 minutes while distilling off distilling by-product acetic acid and unreacted acetic anhydride. A liquid crystal polyester was obtained by incubating at the same temperature for 3 hours. The obtained liquid crystal polyester was cooled to room temperature and pulverized with a pulverizer to obtain liquid crystal polyester powder (particle size: about 0.1 mm to about 1 mm).
It was 261 degreeC when the flow start temperature was measured about this powder (liquid crystalline polyester) using the flow tester.
The obtained powder was heated from 25 ° C. to 250 ° C. over 1 hour, then heated from the same temperature to 295 ° C. over 8 hours, and then kept at that temperature for 3 hours for solid phase polymerization. Thereafter, the powder after solid-phase polymerization was cooled to obtain a liquid crystal polyester. This liquid crystal polyester is designated as B. About B, when the flow start temperature was measured using the flow tester, it was 310 degreeC. This is designated as liquid crystal polyester 2 (the ratio of 2,6-naphthalenediyl group to the total of all aromatic groups; 70.9 mol%).

Production Example 3
In a reactor similar to Production Examples 1 and 2, 994.5 g (7.2 mol) of parahydroxybenzoic acid, 446.9 g (2.4 mol) of 4,4′-dihydroxybiphenyl, 299.0 g of terephthalic acid (1) 8 mol), 99.7 g (0.6 mol) of isophthalic acid, and 1347.6 g (13.2 mol) of acetic anhydride, and the inside of the reactor was sufficiently replaced with nitrogen gas. The temperature was raised to 150 ° C. over a minute, and the mixture was refluxed for 1 hour while maintaining the temperature.
Thereafter, the temperature was raised to 320 ° C. over 2 hours and 50 minutes while distilling off distilling by-product acetic acid and unreacted acetic anhydride, and the time when an increase in torque was observed was regarded as completion of the reaction, and the contents were taken out. . The obtained solid was cooled to room temperature, pulverized by a coarse pulverizer, heated from room temperature to 250 ° C. over 1 hour in a nitrogen atmosphere, heated from 250 ° C. to 285 ° C. over 5 hours, and heated to 285 The polymerization reaction was advanced in a solid layer by maintaining at 3 ° C. for 3 hours. The liquid crystal polyester obtained had a flow initiation temperature of 327 ° C. This is designated as liquid crystal polyester 3 (the ratio of 2,6-naphthalenediyl group to the total of all aromatic groups; 0 mol%).

Examples 1-4, Comparative Examples 1-4
The liquid crystal polyester obtained in Production Examples 1, 2, and 3 and the following components were granulated with a composition shown in Tables 1 and 2 at a cylinder temperature of 350 ° C. using a twin screw extruder (PCM30 HS manufactured by Ikegai Co., Ltd.). A pellet was obtained. In addition, the following were used as a hollow particle and an inorganic filler.

Hollow particles: Glass balloon (manufactured by Sumitomo 3M, trade name: S60HS)
True density 0.6 g / cm ² Pressure resistance 124 MPa
Volume average particle size 27μm
Inorganic filler: Chopped glass (Asahi Fiber Glass Co., Ltd., trade name: CS03JAPX-1)

In the above twin screw extruder, the supply part is provided at two locations, the most upstream part and the downstream part. Liquid crystal polyester and glass fiber are supplied from the most upstream part, and glass balloons are supplied from the downstream part. did.

The pellets obtained were injection molded using a PS40E-5ASE type injection molding machine manufactured by Nissei Plastic Industry Co., Ltd., injection molded at a cylinder temperature of 350 ° C. and a mold temperature of 130 ° C., and the following dimensions were obtained. A test piece having a substantially rectangular parallelepiped shape was obtained.
-Dielectric constant measurement specimen: 64 x 64 x 1 mm
-Dielectric loss tangent measurement specimen: 64 x 64 x 1 mm

The measurement was performed using an HP4291A RF impedance / material analyzer (manufactured by HP), and measurement was performed at a measurement temperature of 23 ° C. and a frequency of 1 MHz to obtain a dielectric constant and a dielectric loss tangent. Further, the frequency was changed to 1 GHz, and the dielectric constant and dielectric loss tangent were obtained. The results are shown in Tables 1 and 2.

The liquid crystal polyester resin composition of the present invention is significantly lower in relative dielectric constant and dielectric loss tangent of the obtained molded product than the resin composition using liquid crystal polyester conventionally used for general purposes, and is excellent in high frequency characteristics. It was found to be a molded product.

Claims (7)

A liquid crystal polyester resin composition comprising the following component (a) and component (b).
(A) It consists of structural units represented by the following (i), (ii) and (iii), and the total of divalent aromatic groups represented by Ar ₁ , Ar ₂ and Ar ₃ is 100 mol%. Liquid crystal polyester in which the aromatic group having a 2,6-naphthalenediyl group is 70 mol% or more.

(In the formula, Ar ₁ is an aromatic group selected from 2,6-naphthalenediyl group, 1,4-phenylene group and 4,4′-biphenylylene group. Ar ₂ and Ar ₃ are each independently An aromatic group selected from a 2,6-naphthalenediyl group, a 1,4-phenylene group, a 1,3-phenylene group, and a 4,4′-biphenylylene group, represented by Ar ₁ , Ar ₂ , and Ar ₃ . In the aromatic group, a part or all of the hydrogen atoms of the aromatic ring in the aromatic group may be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group.
(B) Hollow particles The liquid crystal polyester resin composition according to claim 1, wherein the component (b) is a hollow particle made of glass. The liquid crystal polyester resin composition according to claim 1 or 2, wherein the component (a) is 40 to 80% by weight when the total of the component (a) and the component (b) is 100% by weight. Furthermore, the liquid crystal polyester resin composition in any one of Claims 1-3 formed by mixing 30 weight% or less of a component (c) inorganic filler with respect to the weight of a component (a). The liquid crystal polyester resin composition according to claim 4, wherein the inorganic filler is glass fiber. A molded product obtained by molding the liquid crystal polyester resin composition according to claim 1. The molded article according to claim 6, wherein the relative dielectric constant at a measurement temperature of 23 ° C and a frequency of 1 MHz is 3.0 or less and the dielectric loss tangent is 10 x 10 ^-3 or less.