JP7159693B2 - Liquid crystalline polyester resin composition and molded article made of the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystalline polyester resin composition which has excellent high-temperature toughness and thus can be easily post-processed, which has a low dielectric property and excellent attenuation characteristics, and to a molded article made from the composition.

In recent years, the demand for higher performance plastics has been increasing more and more, and many resins with various new performances have been developed and put on the market. Among them, the optically anisotropic liquid crystalline polyester resin characterized by the parallel arrangement of the molecular chains has attracted attention for its excellent fluidity, heat resistance, mechanical properties, and dimensional stability, and has been used for applications such as micro connectors. Used for precision molded products.

In addition, liquid crystalline polyester resins are known to be excellent in low dielectric properties and attenuation characteristics, and films and molded articles made of liquid crystalline polyester resins are used for circuit boards and antenna parts.

For these applications, isotropy, high rigidity, and low specific gravity are required. Liquid crystalline polyester resins are highly anisotropic and have high specific gravity because the molecules are tightly packed. Sufficient characteristics cannot be obtained.

In order to address such problems, it has been investigated to mix fine glass balloons with liquid crystalline resins (for example, Patent Documents 1 to 8).

For example, in Patent Documents 1, 2, and 6, a liquid crystalline polyester composition that is lightweight and has high dimensional stability is obtained by blending hollow spheres with high pressure resistance into a liquid crystalline polyester.

Patent Document 3 describes a manufacturing method for obtaining a molded body with high surface smoothness by molding at a mold temperature of 140 ° C. or higher. describes a liquid crystalline polyester composition with low anisotropy in .

Patent Document 5 describes a composition with high impact strength in which mica is used in combination to suppress the breakage rate of glass balloons.

Patent Document 8 describes a liquid crystal resin composition having low thermal conductivity by using a liquid crystal polyester having a specific structure, and Patent Document 7 describes a signal reader having excellent vibration damping characteristics and high thermal conductivity. A molded part for is described.

JP-A-2004-323705 Japanese Patent Publication No. 64-74258 JP 2012-30476 A JP 2009-114418 A JP 2011-26541 A Japanese Patent Application Laid-Open No. 2007-297432 Japanese Patent Application Laid-Open No. 2006-152120 JP-A-2001-31848

However, in the compositions obtained by the inventions disclosed in these patent documents, it has not been possible to achieve both a low dielectric constant and vibration damping properties.

In addition, in applications such as speakers that require vibration damping characteristics, curved surfaces and unevenness are added by post-processing to impart desired characteristics such as reverberation suppression, and the inventions disclosed in these patent documents The composition obtained in (1) lacked the high-temperature toughness required for post-processing.

The present invention has been achieved as a result of studying to solve the problems of the above-mentioned conventional technology, and is a liquid crystalline polyester resin that is easy to post-process due to excellent high-temperature toughness, low dielectric and excellent attenuation characteristics. The object is to provide a composition and molded articles made from it.

The present inventors have made sincere studies to achieve the above object, and found that the above object can be achieved for the first time by blending a specific glass balloon with a liquid crystalline polyester resin. reached.

That is, the present invention has a volume hollowness of 81% or more and 85% or less and a true density of 0.40 g/cm ³ or more and 0.48 g/cm ³ or less with respect to 100 parts by weight of the liquid crystalline polyester resin (A), The present invention relates to a liquid crystalline resin composition containing 20 to 25 parts by weight of hollow spheres (B) having a weight average particle diameter of 10 to 30 μm.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a liquid crystalline polyester resin composition which has excellent high-temperature toughness and is easy to post-process, has a low dielectric property and excellent attenuation characteristics, and a molded article made from the composition.

The present invention will be described in detail below.

The liquid crystalline polyester resin (A) used in the present invention comprises structural units selected from, for example, aromatic oxycarbonyl units, aromatic and/or aliphatic dioxy units, aromatic and/or aliphatic dicarbonyl units, and the like. It is a liquid crystalline polyester resin that forms an anisotropic melt phase.

Examples of aromatic oxycarbonyl units include structural units generated from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, etc. Structural units generated from p-hydroxybenzoic acid are preferred. Aromatic and/or aliphatic dioxy units include, for example, 4,4′-dihydroxybiphenyl, hydroquinone, 3,3′,5,5′-tetramethyl-4,4′-dihydroxybiphenyl, t-butylhydroquinone, phenylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-bis(4-hydroxyphenyl)propane, 4,4'-dihydroxydiphenyl ether, ethylene glycol, 1,3-propylene glycol, 1, Structural units generated from 4-butanediol and the like can be mentioned, and structural units generated from 4,4'-dihydroxybiphenyl and hydroquinone are preferred. Aromatic and/or aliphatic dicarbonyl units include, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-4, Structural units generated from 4'-dicarboxylic acid, 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, adipic acid, sebacic acid, and the like. , terephthalic acid and isophthalic acid are preferred.

Specific examples of the liquid crystalline polyester resin include a liquid crystalline polyester resin composed of a structural unit generated from p-hydroxybenzoic acid and a structural unit generated from 6-hydroxy-2-naphthoic acid, and a structure generated from p-hydroxybenzoic acid. units, structural units generated from 6-hydroxy-2-naphthoic acid, structural units generated from an aromatic dihydroxy compound, and structural units generated from an aromatic dicarboxylic acid and/or an aliphatic dicarboxylic acid, a liquid crystalline polyester resin, Structural units generated from p-hydroxybenzoic acid, structural units generated from 4,4′-dihydroxybiphenyl, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid and/or aliphatic dicarboxylic acids such as adipic acid and sebacic acid Liquid crystalline polyester resin composed of structural units generated, structural units generated from p-hydroxybenzoic acid, structural units generated from 4,4'-dihydroxybiphenyl, structural units generated from hydroquinone, fragrances such as terephthalic acid and isophthalic acid Liquid crystalline polyester resin composed of structural units generated from aliphatic dicarboxylic acids such as dicarboxylic acid and/or adipic acid, sebacic acid, structural units generated from p-hydroxybenzoic acid, structural units generated from ethylene glycol, terephthalic acid and/or a liquid crystalline polyester resin composed of structural units derived from isophthalic acid, structural units derived from p-hydroxybenzoic acid, structural units derived from ethylene glycol, structural units derived from 4,4'-dihydroxybiphenyl, and terephthalic acid. A liquid crystalline polyester resin composed of structural units generated from acids and/or structural units generated from aliphatic dicarboxylic acids such as adipic acid and sebacic acid, structural units generated from p-hydroxybenzoic acid, structural units generated from ethylene glycol, Structural units generated from aromatic dihydroxy compounds, liquid crystalline polyester resins composed of structural units generated from aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid, from 6-hydroxy-2-naphthoic acid Liquid crystalline polyester resins composed of structural units formed from structural units formed from 4,4'-dihydroxybiphenyl, structural units formed from 2,6-naphthalenedicarboxylic acid, and the like.

Among these liquid crystalline polyester resins, liquid crystalline polyester resins composed of the following structural units (I), (II), (III), (IV) and (V) are preferable from the viewpoint of low dust generation. This is because such a liquid crystalline polyester resin has a large number of copolymerized units, so that the liquid crystallinity is low, and fibrillation, which is a characteristic of the liquid crystalline polyester resin, is less likely to occur.

The structural unit (I) is a structural unit generated from p-hydroxybenzoic acid, the structural unit (II) is a structural unit generated from 4,4'-dihydroxybiphenyl, and the structural unit (III) is a structure generated from hydroquinone. structural unit (IV) is a structural unit generated from terephthalic acid, and structural unit (V) is a structural unit generated from isophthalic acid.

Structural unit (I) is preferably 65 to 80 mol % relative to the total of structural units (I), (II) and (III). The lower limit is more preferably 68 mol % or more because the amount of generated gas decreases, and the upper limit is more preferably 78 mol % or less from the viewpoint of toughness.

Structural unit (II) is preferably 55 to 85 mol% of the total of structural units (II) and (III). In particular, since the amount of generated gas decreases, the lower limit is more preferably 60 mol% or more, most preferably 70 mol% or more, and from the viewpoint of toughness, the upper limit is more preferably 82 mol% or less, most preferably. 80 mol % or less.

Structural unit (IV) is preferably 50 to 95 mol% of the total of structural units (IV) and (V). In particular, since the amount of generated gas decreases, the lower limit is more preferably 55 mol% or more, most preferably 60 mol% or more, and the upper limit is more preferably 85 mol% or less from the viewpoint of toughness, most preferably 85 mol% or less. Preferably, it is 75 mol % or less.

The sum of structural units (II) and (III) and the sum of (IV) and (V) are preferably substantially equimolar. Here, "substantially equimolar" means that the structural units constituting the polymer main chain excluding the terminal are equimolar, and when the structural unit constituting the terminal is included, it is not necessarily equimolar. Not exclusively. Excess dicarboxylic acid or dihydroxy moieties may be added to control the end groups of the polymer.

In the embodiment of the present invention, the content of each structural unit in (A) the liquid crystalline polyester resin can be calculated by the following process. That is, the liquid crystalline polyester resin is weighed into an NMR (nuclear magnetic resonance) test tube, dissolved in ^a solvent in which the liquid crystalline polyester resin is soluble (for example, pentafluorophenol/heavy tetrachloroethane-d ₂ mixed solvent), H-NMR spectrum measurement is performed. The content of each structural unit can be calculated from the peak area ratio derived from each structural unit.

The melting point of the liquid crystalline polyester resin in the present invention is preferably 300 to 350° C. from the viewpoint of workability and fluidity, and the lower limit thereof is more preferably 310° C. or higher, particularly preferably 320° C. or higher, from the viewpoint of workability. From the viewpoint of fluidity, the upper limit is more preferably 340°C or lower, particularly preferably 330°C or lower. Such a melting point is preferable because generation of decomposition gas during processing can be suppressed and fluidity is sufficiently exhibited.

The melting point (Tm) of (A) the liquid crystalline polyester resin of the present invention can be measured by the following method. In the differential calorimetry, after observing the endothermic peak temperature (Tm ₁ ) observed when measuring the liquid crystalline polyester resin under the temperature rising condition of 40° C./min from room temperature, the temperature was kept at Tm ₁ +20° C. for 5 minutes. After that, the temperature was once cooled to room temperature under the temperature decreasing condition of 20° C./min, and the endothermic peak temperature (Tm ₂ ) observed when measured again under the temperature increasing condition of 20° C./min was taken as the melting point (Tm).

Further, the melt viscosity of (A) the liquid crystalline polyester resin in the present invention is preferably 1 to 100 Pa s, and from the viewpoint of workability, the lower limit thereof is more preferably 3 Pa s or more, and particularly preferably 5 Pa s or more. From the viewpoint of fluidity, the upper limit is more preferably 50 Pa·s or less, particularly preferably 30 Pa·s or less. The melt viscosity is a value measured with a Koka-type flow tester under the conditions of the melting point of the liquid crystalline polyester resin +10° C. and the shear rate of 1,000/s.

The (A) liquid crystalline polyester resin of the present invention can be obtained by a known polyester polycondensation method. For example, in the case of the liquid crystalline polyester resin composed of the structural units (I), (II), (III), (IV) and (V) described above, the following production methods are preferred.

(1) A method of producing a liquid crystalline polyester from p-acetoxybenzoic acid, 4,4'-diacetoxybiphenyl, diacetoxybenzene, terephthalic acid and isophthalic acid by deacetic acid polycondensation reaction.

(2) p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, terephthalic acid and isophthalic acid are reacted with acetic anhydride to acylate the phenolic hydroxyl groups, followed by a deacetic acid polycondensation reaction to produce a liquid crystalline polyester. how to manufacture

(3) A method of producing a liquid crystalline polyester from phenyl ester of p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, and diphenyl esters of terephthalic acid and isophthalic acid by dephenol polycondensation reaction.

(4) p-hydroxybenzoic acid and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid are reacted with a predetermined amount of diphenyl carbonate to form diphenyl esters, respectively, followed by aromatics such as 4,4'-dihydroxybiphenyl and hydroquinone. A method of producing a liquid crystalline polyester by adding a group dihydroxy compound and performing a dephenol polycondensation reaction.

In the present invention, when the liquid crystalline polyester resin is produced by the deacetic acid polycondensation reaction, a melt polymerization method is preferred in which the reaction is performed under reduced pressure at a temperature at which the liquid crystalline polyester resin melts to complete the polycondensation reaction. For example, in the case of the liquid crystalline polyester resin composed of the structural units (I), (II), (III), (IV) and (V) described above, a predetermined amount of p-hydroxybenzoic acid, 4,4' - Dihydroxybiphenyl, hydroquinone, terephthalic acid, isophthalic acid, and acetic anhydride are charged into a reaction vessel equipped with a stirring blade and a distillation tube and equipped with a discharge port at the bottom, and heated with stirring under a nitrogen gas atmosphere. After acetylating the hydroxyl group, the temperature is raised to the melting temperature of the liquid crystalline polyester resin, and polycondensation is performed under reduced pressure to complete the reaction.

The obtained polymer is pressurized in the reaction vessel at a temperature at which it melts, for example, to about 1.0 kg/cm ² (0.1 MPa), and is discharged in a strand form from a discharge port provided at the bottom of the reaction vessel. be able to. The melt polymerization method is an advantageous method for producing a uniform polymer, and can obtain an excellent polymer with less gas generation, and is preferred.

Although the polycondensation reaction of the liquid crystalline polyester resin proceeds without a catalyst, metal compounds such as stannous acetate, tetrabutyl titanate, potassium acetate, sodium acetate, antimony trioxide, and metallic magnesium can also be used.

The liquid crystalline polyester (A) of the present invention can be used by mixing two or more liquid crystalline polyesters.

The hollow sphere used in the present invention has a volumetric hollowness of 81% or more and 85% or less, a true density of 0.48 g/cm ³ or less and 0.40 g/cm ³ or more, and a weight average particle diameter of 10 to 30 μm. As the material of (B), glass, silica, light calcium carbonate, shirasu, fly ash, diatomaceous earth, alumina, zirconia, magnesia, borate, phosphate, stainless alloy, urea resin, phenol resin, etc. can be used. Glass, silica, and shirasu are preferred, and glass is most preferred.

As the glass, quartz glass, alumina borosilicate glass, borosilicate glass, soda-lime glass, etc. are used, and alumina borosilicate glass or borosilicate glass is preferable, and borosilicate glass is more preferable from the viewpoint of dielectric constant.

Examples of hollow spheres made of glass include porous foamed glass beads and monoporous glass balloons, with glass balloons being preferred.

The hollow sphere used in the present invention has a volume hollowness of 81% or more and 85% or less and a true density of 0.48 g/cm ³ or less and 0.40 g/cm ³ or more.

The volumetric hollowness indicates the ratio of the volume occupied by voids to the total volume, and there is a correlation that the higher the volumetric hollowness, the lower the true density.

The volumetric hollowness is essentially 81% or more and 85% or less, more preferably 81% or more and 83% or less. In this range of volumetric hollowness, it is possible to achieve both dielectric constant and vibration damping characteristics, which is preferable. On the other hand, if the volume hollowness is less than 81%, the dielectric constant increases, and if the volumetric hollowness exceeds 85%, the damping characteristics deteriorate, which is not preferable.

The volumetric hollowness can be calculated by measuring the inner diameter and outer diameter of the central section of the glass balloon with an optical measuring microscope.
Volume hollowness = (inner diameter) ³ / (outer diameter) ³ × 100 (%)

The volume hollowness is a number average value, and can be calculated as a number average value by measuring 50 hollow particles.

The true density is essentially 0.40 g/cm ³ or more and 0.48 g/cm ³ or less, more preferably 0.43 g/cm ³ or more and 0.47 g/cm ³ or less. In this range of true density, it is possible to achieve both dielectric constant and vibration damping characteristics, which is preferable. On the other hand, if the true density is less than 0.40 g/cm ³ , the attenuation characteristics deteriorate, and if the true density exceeds 0.48 g/cm ³ , the dielectric constant deteriorates, which is not preferable.

True density is measured, for example, using a pycnometer according to ASTM D2840-69.

Also, the weight average particle size of the hollow spheres (B) is essentially 10 to 30 μm, more preferably 15 to 25 μm.

If the weight average particle size is within this range, good vibration damping properties and post-processability can be obtained, and if the weight average particle size is less than 10 μm, the vibration damping properties and post-process properties will deteriorate. If the particle size exceeds 30 μm, the vibration damping characteristics are deteriorated, which is not preferable.

The weight-average particle size can be a value obtained by measuring, for example, the ash content obtained by baking the composition using a laser diffraction particle size distribution analyzer.

The compressive strength of the hollow sphere (B) of the present invention is preferably 100 MPa or more and less than 120 MPa, more preferably 105 MPa to 115 MPa. When the pressure resistance is within this range, the breakage rate of the hollow spheres can be within a preferable range, and it is easy to achieve both vibration damping characteristics and dielectric constant.

The pressure resistance strength is measured, for example, by the glycerol method, by mixing a certain amount of glass balloon and glycerol, sealing it so that air does not enter, observing the volume change when pressurized, and the pressure exceeding the breakage rate of 10% can be measured as compressive strength. It can be done by pressurizing in glycerol and measuring the limit pressure that does not break.

In addition, the surface of the glass balloon can be treated with a silane coupling agent such as aminosilane, ureidosilane, epoxysilane, phenylsilane, etc. in order to improve compatibility with the liquid crystalline polyester.

The blending amount of the hollow spheres in the present invention is 20 to 25 parts by weight, more preferably 21 to 24 parts by weight, per 100 parts by weight of the liquid crystalline polyester. If the amount is less than 20 parts by weight per 100 parts by weight of the liquid crystalline polyester, the effect of lowering the dielectric constant is not sufficient.

The liquid crystalline resin composition of the present invention may further contain a filler in order to impart mechanical strength and other properties. The filler is not particularly limited, but fibrous, plate-shaped, powdery, granular fillers and the like can be used. Specifically, for example, glass fiber, PAN-based or pitch-based carbon fiber, stainless fiber, metal fiber such as aluminum fiber and brass fiber, organic fiber such as aromatic polyamide fiber and liquid crystalline polyester fiber, gypsum fiber, ceramic fiber , asbestos fiber, zirconia fiber, alumina fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool, potassium titanate whisker, barium titanate whisker, aluminum borate whisker, silicon nitride whisker, etc. powdery, granular or plate-like fillers such as wood, mica, talc, kaolin, silica, glass beads, glass flakes, clay, molybdenum disulfide, wollastonite, titanium oxide, zinc oxide, calcium polyphosphate and graphite. . The above-mentioned filler used in the present invention may be used by treating its surface with a known coupling agent (e.g., silane-based coupling agent, titanate-based coupling agent, etc.) or other surface treatment agent. .

Among these fillers, glass fiber and PAN-based carbon fiber are particularly preferred from the standpoint of balance between availability and mechanical strength.

The type of glass fiber or PAN-based carbon fiber is not particularly limited as long as it is generally used for reinforcing resins. For example, it can be selected from long fiber type and short fiber type chopped strands and milled fibers. .

As the composition of the glass fiber, E glass, D glass, H glass, etc. can generally be applied. Among these, E glass and D glass are preferable, and D glass is more preferable.

D-glass is borosilicate glass and is preferable because it has a dielectric constant of 5.0 or less at 10 GHz. The PAN-based carbon fiber preferably has a specific elastic modulus value of 100,000 to 400,000 cm. The specific elastic modulus is calculated by dividing the tensile elastic modulus and the density of carbon fibers measured by a known method.

The glass fiber or PAN-based carbon fiber preferably has an average fiber diameter of 4 to 20 μm, more preferably 5 to 16 μm. There is no particular lower limit, and if the thickness is 4 μm or more, sufficient effects can be obtained. If the average fiber diameter exceeds 20 µm, the strength tends to decrease. The average fiber diameter is generally obtained by observing 100 or more fibers using a scanning electron microscope (SEM) at a magnification of 800, and calculating the number average fiber diameter.

Pre-treating the glass fiber or carbon fiber with a coupling agent such as an isocyanate-based compound, an organic silane-based compound, an organic titanate-based compound, an organic borane-based compound, and an epoxy compound for use provides better mechanical strength. It is preferable in the sense that it can be obtained.

The amount of the filler other than the hollow spheres (B) is generally 1-50 parts by weight, preferably 5-15 parts by weight, per 100 parts by weight of the liquid crystalline resin composition.

Within this range, the dielectric constant can be lowered and the attenuation characteristics can be improved, which is preferable.

When the filler other than the hollow spheres (B) is PAN-based carbon fiber, it is preferably 5 to 10 parts by weight per 100 parts by weight of the liquid crystalline resin composition. This range of the amount of the PAN-based carbon fiber to be blended is preferable because the damping characteristics are particularly good.

The thermoplastic resin composition of the present invention contains antioxidants and heat stabilizers (e.g. hindered phenols, hydroquinones, phosphites and substituted products thereof), UV absorbers (e.g. resorcinol, salicylate), phosphorous acid. Colorants including salts, anti-staining agents such as hypophosphites, lubricants and release agents (such as montanic acid and its metal salts, its esters, its half-esters, stearyl alcohol, stearamide and polyethylene wax), dyes and pigments , carbon black as a conductive agent or coloring agent, crystal nucleating agent, plasticizer, flame retardant (brominated flame retardant, phosphorus flame retardant, red phosphorus, silicone flame retardant, etc.), flame retardant aid, antistatic agent, etc. A polymer other than a thermoplastic resin can be blended to further impart desired properties.

The method for producing the composition of the present invention is not particularly limited, but a method of adding hollow spheres to the liquid crystalline polyester in the polymerization step or melt-kneading step of the liquid crystalline polyester is used. A preferred method is to mix the glass balloons with the liquid crystalline polyester in the step of melt-kneading the liquid crystalline polyester.

A known method can be used for the melt-kneading. For example, a Banbury mixer, a rubber roll machine, a kneader, a single-screw or twin-screw extruder, etc. can be used to melt and knead the liquid crystal resin at a liquid crystal starting temperature of -50°C to a melting point of +50°C to form a liquid crystalline resin composition. . Among them, a twin-screw extruder is preferred.

Here, the liquid crystal initiation temperature is the temperature at which the liquid crystal starts to flow under the condition of a shear rate of 1000 (1/sec). It is determined by measuring the temperature at which the entire field of view begins to flow at a heating rate of 5.0° C./min and an objective lens of 60×.

The configuration of the twin-screw extruder may be either an intermeshing type screw or a non-meshing type screw, but the intermeshing type screw is preferred from the viewpoint of resin kneading efficiency. The direction of rotation may be biaxial opposite direction rotation or biaxial codirectional rotation, but biaxial coaxial rotation is preferable. The screw length/diameter ratio (L/D) is preferably 25-60, more preferably 30-50, most preferably 40-45.

It has a feeder or a side feeder, preferably the liquid crystalline polyester is fed in, and the hollow spheres can be added from the feeder or the side feeder. The addition from the side feeder of the hollow spheres is preferable because the dispersed state can be more uniform.

The extruder preferably has one or more vents, more preferably two or more vents, and the vents should be installed behind the kneading block after the side feeder. is preferred, and more preferably it is also installed in front of the kneading block in front of the side feeder, since the gas produced by the resin can be efficiently removed.

The hollow spheres (B) of the present invention preferably have a shape retention rate of 80 to 85% in the composition in order to exhibit the effects of the present invention. If the shape retention rate is less than 80%, the dielectric constant tends to decrease, and if the shape retention rate exceeds 85%, the post-processability tends to deteriorate.

The shape retention rate of the hollow spheres in the composition or molded article can be calculated from the difference between the measured specific gravity and the theoretical specific gravity.

As the kneading method, 1) a method of collectively kneading the liquid crystalline polyester, the hollow spheres, optional fillers and other additives, and 2) a liquid crystalline polyester containing other additives at a high concentration. A method of preparing a composition (master pellet) and then adding a liquid crystalline polyester, hollow spheres, an optional filler and the remaining additives to a prescribed concentration (master pellet method), 3) liquid crystallinity Any method may be used, such as a divided addition method in which the polyester and a portion of the other additives are kneaded once, and then the remaining hollow spheres, the optional filler and the remaining additives are added.

In the liquid crystalline resin composition of the present invention thus obtained, by breaking the hollow spheres at a specific ratio, it is possible to achieve both a reduction in the dielectric constant and an improvement in the attenuation coefficient, both of which are difficult to achieve at the same time. Are better.

The liquid crystalline resin composition of the present invention can be molded by a conventional molding method such as injection molding, extrusion molding, press molding, etc., and has excellent surface appearance (color tone), mechanical properties, heat resistance, and flame retardancy. , pipes, films, fibers, etc.

In addition, since the molded article of the present invention has a characteristic of becoming extremely soft at high temperatures, it can be easily shaped by secondary processing such as hot pressing and embossing.

The liquid crystalline resin composition thus obtained can be used, for example, in various gears, various cases, sensors, LED lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, capacitors, variable condenser cases, optical pickups, and oscillators. terminals, various terminal boards, transformers, plugs, printed wiring boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, housings, semiconductors, liquid crystal display parts, FDD carriages, FDD chassis, HDD parts, Electric/electronic parts such as motor brush holders, parabolic antennas, computer-related parts; VTR parts, TV parts, irons, hair dryers, rice cooker parts, microwave oven parts, acoustic parts, audio/laser discs (registered trademark)・Audio device parts such as compact discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, household electrical appliance parts, office computer-related parts, telephone-related parts, facsimile-related parts, copiers machine parts, cleaning jigs, oilless bearings, stern bearings, underwater bearings, motor parts, machine parts such as lighters and typewriters, microscopes, binoculars, cameras, watches, etc. Optical equipment, precision machinery related parts; alternator terminals, alternator connectors, IC regulators, potentiometer bases for light gear, various valves such as exhaust gas valves, fuel related / exhaust system / intake system various pipes, air intake nozzle snorkel, intake manifold , fuel pump, engine coolant joint, carburetor main body, carburetor spacer, exhaust gas sensor, coolant sensor, oil temperature sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake butt wear sensor, thermostat base for air conditioner , air conditioner motor insulators, heating hot air flow control valves, brush holders for radiator motors, water pump impellers, turbine vanes, wiper motor related parts, dust tributors, starter switches, starter relays, wire harnesses for transmissions, window washer nozzles , air conditioner panel switch board, fuel related Automobile and vehicle related parts such as coils for electromagnetic valves, connectors for fuses, horn terminals, insulating plates for electric parts, step motor rotors, lamp sockets, lamp reflectors, lamp housings, brake pistons, solenoid bobbins, engine oil filters, ignition device cases, etc. etc. can be used. Film for magnetic recording media, photographic film, capacitor film, electrical insulating film, packaging film, drawing film, ribbon film, and sheet applications for automobile interior ceilings, door trims, and instrument panels. cushioning materials for bumpers and side frames, sound absorbing pads for bonnet backs, seat materials, pillars, fuel tanks, brake hoses, window washer fluid nozzles, air conditioner refrigerant tubes and their peripheral parts. It is especially suitable for applications such as speakers, microphones, and headphones that require dielectric properties, vibration damping properties, and post-processing properties.

The effects of the present invention will be described below with reference to examples. All percentages and parts in the examples are by weight unless otherwise specified. Moreover, the physical properties shown in the examples were measured as follows.

The evaluation method for each characteristic is as follows.

[Post-processability]
The liquid crystalline polyester resin composition obtained in each example and comparative example was treated with a FANUC ROBOSHOT α-30C (manufactured by FANUC CORPORATION), and the cylinder temperature was set to +10° C. of the melting point of the liquid crystalline polyester resin. Injection molding was performed at a mold temperature of 90° C. and an injection speed of 100 mm/s to prepare strip-shaped test pieces of 130 mm×13 mm×0.3 mm thickness.

This test piece was subjected to a 360° bending test at 250°C, and the breaking angle was evaluated.

[Permittivity]
In the same manner as above, a rectangular plate of length 60 mm×width 50 mm×1 mm thickness was formed under the condition of one speed and one pressure, and the dielectric constant at 10 GHz was measured by the perturbation closed cavity resonance method using a network analyzer.

[Vibration damping characteristics]
In the same manner as described above, under the conditions of one speed and one pressure, a square plate of 100 mm square × 2 mm thickness was molded, and the attenuation coefficient of the obtained molded product was measured using a preamplifier (B&K 2639S model) and a power amplifier (B&K 2706 model). model) and a two-channel FFT analyzer (B&K model 2034) were used to measure in the region of 200-300 Hz.

(A) to (E) used in each example are shown below.

[Form retention rate]
The shape retention rate of the hollow spheres was obtained by measuring the specific gravity of the molded article obtained above with an electronic hydrometer ED-120T at 23°C with an aqueous solvent, calculating the percentage by weight of the damaged product from the following formula, and obtaining the shape retention rate ( %) = 100 - calculated as weight % broken.
Specific gravity = 100/{Specific gravity of liquid crystalline resin × Weight % of liquid crystalline resin compounded + True specific gravity of glass balloon × (% compounded weight of glass balloon - % of broken weight} + Specific gravity of glass of glass balloon X Broken weight % +specific gravity of filler×mixed weight % of filler+specific gravity of other additives×mixed weight % of other additives}.

(A) Liquid crystalline polyester resin [Reference Example 1] Synthesis of liquid crystalline polyester resin (A-1) 870 parts by weight of p-hydroxybenzoic acid, 4,4′ were placed in a 5 L reaction vessel equipped with a stirring blade and a distillation tube. 327 parts by weight of dihydroxybiphenyl, 89 parts by weight of hydroquinone, 292 parts by weight of terephthalic acid, 157 parts by weight of isophthalic acid and 1367 parts by weight of acetic anhydride (1.03 equivalents of total phenolic hydroxyl groups) were charged and stirred under a nitrogen gas atmosphere. After reacting at 145°C for 2 hours, the temperature was increased to 320°C in 4 hours. heated up. Thereafter, the polymerization temperature was maintained at 320° C., the pressure was reduced to 1.0 mmHg (133 Pa) over 1.0 hour, the reaction was continued for 90 minutes, and polymerization was completed when the torque required for stirring reached 15 kg·cm. . Next, the inside of the reaction vessel is pressurized to 1.0 kg/cm2 (0.1 MPa), the polymer is discharged into strands through a mouthpiece having a circular discharge port with a diameter of 10 mm, and the liquid crystal is pelletized by a cutter. A flexible polyester resin (A-1) was obtained.

A composition analysis of this liquid crystalline polyester resin (A-1) revealed that a structural unit derived from p-hydroxybenzoic acid (structural unit (I)) and a structural unit derived from 4,4′-dihydroxybiphenyl (structural unit ( II)) and the structural unit derived from hydroquinone (structural unit (III)), the ratio of the structural unit derived from p-hydroxybenzoic acid (structural unit (I)) was 70 mol%. 4,4'-dihydroxybiphenyl-derived structural unit (structural unit (II )) was 70 mol %. The ratio of the terephthalic acid-derived structural unit (structural unit (IV)) to the total of the terephthalic acid-derived structural unit (structural unit (IV)) and the isophthalic acid-derived structural unit (structural unit (V)) was 65 mol%. Met. The total of structural units derived from 4,4′-dihydroxybiphenyl (structural unit (II)) and structural units derived from hydroquinone (structural unit (III)) is 23 mol% of all structural units, and terephthalic acid-derived The structural unit (structural unit (IV)) and the isophthalic acid-derived structural unit (structural unit (V)) were 23 mol % of the total structural units. The melting point (Tm) of the liquid crystalline polyester resin (A-2) was 314°C. The melt viscosity measured at a temperature of 324° C. and a shear rate of 1,000/s using a Koka flow tester (orifice 0.5φ×10 mm) was 20 Pa·s.

[Reference Example 2] Synthesis of liquid crystalline polyester resin (A-2) 932 parts by weight of p-hydroxybenzoic acid, 251 parts by weight of 4,4'-dihydroxybiphenyl, 99 parts by weight of hydroquinone, 284 parts by weight of terephthalic acid, 90 parts by weight of isophthalic acid and 1252 parts by weight of acetic anhydride (1.09 equivalents of the total phenolic hydroxyl groups) were charged and reacted at 145°C for 1 hour under a nitrogen gas atmosphere with stirring. After that, the jacket temperature was raised from 145°C to 270°C at an average temperature increase rate of 0.68°C/min, and from 270°C to 350°C at an average temperature increase rate of 1.4°C/min. rice field. The heating time was 4 hours. After that, the polymerization temperature was maintained at 350° C., the pressure was reduced to 1.0 mmHg (133 Pa) over 1.0 hour, the reaction was continued, and polymerization was completed when the torque required for stirring reached 10 kg·cm. Next, the inside of the reaction vessel is pressurized to 1.0 kg/cm2 (0.1 MPa), the polymer is discharged into strands through a mouthpiece having a circular discharge port with a diameter of 10 mm, and the liquid crystal is pelletized by a cutter. A curable polyester resin (A-2) was obtained.

A composition analysis of this liquid crystalline polyester resin (A-2) revealed that a structural unit derived from p-hydroxybenzoic acid (structural unit (I)) and a structural unit derived from 4,4′-dihydroxybiphenyl (structural unit ( II)) and the structural unit derived from hydroquinone (structural unit (III)), the ratio of the structural unit derived from p-hydroxybenzoic acid (structural unit (I)) was 75 mol%. 4,4'-dihydroxybiphenyl-derived structural unit (structural unit (II )) was 60 mol %. The ratio of the terephthalic acid-derived structural unit (structural unit (IV)) to the total of the terephthalic acid-derived structural unit (structural unit (IV)) and the isophthalic acid-derived structural unit (structural unit (V)) was 76 mol%. Met. The total of structural units derived from 4,4'-dihydroxybiphenyl (structural unit (II)) and structural units derived from hydroquinone (structural unit (III)) is 20 mol% of all structural units, and terephthalic acid-derived The structural unit (structural unit (IV)) and the isophthalic acid-derived structural unit (structural unit (V)) were 20 mol % of the total structural units. The melting point (Tm) of the liquid crystalline polyester resin (A-2) was 325°C. The melt viscosity measured at a temperature of 335° C. and a shear rate of 1,000/s using a Koka flow tester (orifice 0.5φ×10 mm) was 8 Pa·s.

(B) Hollow sphere B-1 iM16K made by 3M (soda lime borosilicate glass balloon: weight average particle diameter 20 μm, volumetric hollowness 81.9%, true density 0.46 g/cm ³ , compressive strength 110 MPa)
The hollow spheres used in Comparative Examples are shown below.

(E) Other hollow spheres E-1 3M S60HS (soda lime borosilicate glass balloon: weight average particle diameter 24 μm, volumetric hollowness 76%, true density 0.60 g/cm ³ , compressive strength 124 MPa)
E-2 iM30K made by 3M (soda lime borosilicate glass balloon: weight average particle diameter 27 μm, volumetric hollowness 76%, true density 0.6 g/cm ³ , compressive strength 193 MPa)
E-3 3M K46 (soda lime borosilicate glass balloon: weight average particle diameter 40 μm, volumetric hollowness 82%, true density 0.47 g/cm ³ , compressive strength 41 MPa)
The properties of the hollow spheres were measured by the following methods.

[Weight average particle size]
The moldings obtained for the dielectric constant measurement described above were ashed and the glass balloons were isolated by a sedimentation method. The weight-average particle size was determined using a laser diffraction particle size distribution meter (SALD-3000 manufactured by Shimadzu Corporation).

[Volume hollowness]
The molded article obtained for dielectric constant measurement was cut with a microtome and observed with an optical measuring microscope to measure the inner diameter and outer diameter of the glass balloon, and the volumetric hollowness was calculated from the following formula.
Fifty glass balloons with an outer diameter in the range of 95 to 100% of the maximum observed value were measured, and the number-average volumetric hollowness was calculated.
Volume hollowness = (inner diameter) ³ / (outer diameter) ³ × 100 (%)

[true density]
The moldings obtained for the dielectric constant measurement described above were ashed and the glass balloons were isolated by a sedimentation method. The true density of the glass balloon was measured with a pycnometer AUTO TRUE DENSER MAT-7000 (according to ASTM D2840-69).

[Pressure strength]
The moldings obtained for the dielectric constant measurement described above were ashed and the glass balloons were isolated by a sedimentation method. According to the glycerol method, a glass balloon was placed in glycerol, sealed to prevent air from entering, and the volume change when pressurized was observed.

(C) Glass fiber C-1 Nippon Electric Glass Co., Ltd. DPF80M-01N (dielectric constant 4.2 (10 GHz) borosilicate glass milled fiber)

(D) Other glass fibers D-1 EPG70MD-01N manufactured by Nippon Electric Glass Co., Ltd. (dielectric constant 6.6 (10 GHz) alumina borosilicate glass milled fiber)

(F) PAN-based carbon fiber F-1 TV14-006 manufactured by Toray Industries, Inc. (tensile modulus of elasticity 230 GPa)

[Examples 1 to 9, Comparative Examples 1 to 5]
Using a coaxially rotating vented twin-screw extruder (manufactured by Japan Steel Works, Ltd., TEX-44) with a screw diameter of 44 mm, the liquid crystalline polyester resin (A) was charged from a hopper in the amount shown in Table 1, and hollow spheres were obtained. (B) or (E) and glass fiber (C), carbon fiber (F) or (D) were charged from an intermediate supply port in the amounts shown in Table 1. The cylinder temperature is set to the melting point of the liquid crystalline polyester resin (A) + 10°C (when two types of liquid crystalline polyester are used, the melting point of the liquid crystalline polyester with the higher melting point + 10°C), and melted and kneaded. Pellets of a liquid crystalline polyester resin composition were obtained. Various characteristic values were evaluated using the obtained pellets. Table 1 shows the test results.

As is clear from the results in Table 1, the liquid crystalline polyester resin compositions of Examples are excellent in dielectric constant, vibration damping characteristics, and post-processability (Examples 1 to 8). It is also found that the combined use of the low dielectric glass fiber (C) further improves the vibration damping property, which is the effect of the present invention, without lowering the dielectric property (Examples 4 to 6).

In particular, it can be seen that when the PAN-based carbon fiber (F) is used together, a molded article having particularly excellent vibration damping characteristics can be obtained (Example 9).

On the other hand, it can be seen that these characteristics cannot be obtained with hollow spheres that do not fall within the ranges of particle diameter, volumetric hollowness, and true density defined by the present invention (Comparative Examples 3 to 5). Moreover, it is found that the effects of the present invention cannot be obtained when the blending amount is too much or too less than the range defined by the present invention (Comparative Examples 1 and 2).

The liquid crystalline polyester resin composition of the present invention can be used for various gears, various cases, sensors, LED parts, liquid crystal backlight bobbins, connectors, sockets, resistors, relay cases, relay spools and bases, switches, coil bobbins, capacitors, Varicon cases, optical pickups, oscillators, various terminal boards, transformers, plugs, printed wiring boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, housings, semiconductors, liquid crystal display parts, FDD carriages , FDD chassis, HDD parts, motor brush holders, parabolic antennas, computer-related parts; VTR parts, TV parts (plasma, organic EL, liquid crystal), irons, hair dryers, rice cooker parts, Microwave oven parts, audio parts, voice equipment parts such as audio equipment, laser discs (registered trademark) and compact discs, lighting parts, refrigerator parts, air conditioner parts, household electrical appliance parts, office computer parts, telephones Related parts, facsimile related parts, copier related parts, cleaning jigs, various bearings such as oilless bearings, stern bearings, underwater bearings, motor parts, machine related parts such as lighters and typewriters, microscopes, binoculars , optical equipment such as cameras and clocks, precision machinery related parts; alternator terminals, alternator connectors, IC regulators, potentiometer bases for light dimmers, various valves such as exhaust gas valves, fuel related, exhaust system, intake system various pipes, Air intake nozzle snorkel, intake manifold, fuel pump, engine coolant joint, carburetor main body, carburetor spacer, exhaust gas sensor, coolant sensor, oil temperature sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake butt Abrasion sensors, thermostat bases for air conditioners, motor insulators for air conditioners, hot air flow control valves, brush holders for radiator motors, water pump impellers, turbine vanes, wiper motor related parts, dust tributors, starter switches, starter relays, transmissions wire harness, window washer nozzle, air conditioner Panel switch board, fuel-related electromagnetic valve coil, fuse connector, ECU connector, horn terminal, electric component insulating plate, step motor rotor, lamp socket, lamp reflector, lamp housing, brake piston, solenoid bobbin, engine oil filter, ignition It can be used for automobiles and vehicle-related parts such as device cases. When it is used as a film, it is used as a film for magnetic recording media, and when it is used as a sheet, mention may be made of door trims, cushioning materials for bumpers and side frames, seat materials, pillars, fuel tanks, brake hoses, nozzles for window washer fluid, tubes for air conditioner refrigerants, etc. can be done.

In particular, the liquid crystalline polyester resin composition and molded article of the present invention are suitably used for applications such as speakers, microphones, and headphones that require dielectric properties, vibration damping properties, and post-processability.

Claims (5)

With respect to 100 parts by weight of the liquid crystalline polyester resin (A), the volume hollowness is 81% or more and 85% or less, the true density is 0.40 g/cm ³ or more and 0.48 g/cm ³ or less, and the weight average particle A liquid crystalline polyester resin composition containing 20 to 25 parts by weight of hollow spheres (B) having a diameter of 10 to 30 μm, wherein the shape retention rate of the hollow spheres (B) in the liquid crystalline resin composition is 80 to 85. %. 2. The liquid crystalline polyester resin composition according to claim 1, wherein the pressure resistance of the hollow spheres (B) is 100 MPa or more and 120 MPa or less. 3. The liquid crystalline polyester according to claim 1, further comprising 5 to 15 parts by weight of a glass fiber (C) having a dielectric constant of 5.0 or less at 10 GHz with respect to 100 parts by weight of the liquid crystalline polyester resin (A). Resin composition. 3. The liquid crystalline polyester resin composition according to claim 1, further comprising 5 to 10 parts by weight of the PAN-based carbon fiber (F) with respect to 100 parts by weight of the liquid crystalline polyester resin (A). A molded article made of the liquid crystalline polyester resin composition according to any one of claims 1 to 4.