Liquid crystal polyester resin composition

Abstract

To provide a liquid crystalline polyester resin composition which is improved in mechanical properties and heat resistance while maintaining sliding properties.SOLUTION: There is provided a liquid crystalline polyester resin composition which comprises a liquid crystalline polyester containing a repeating unit represented by the formulas (I) to (V) [wherein, p, q r, and s are composition ratios (mol%) of each repeating unit in the liquid crystal polyester, respectively and satisfy the following conditions: 60≤p+q≤78, 0.05≤q≤5, 11≤r≤20 and 11≤s≤20], a fluororesin having an average particle diameter of 25 μm or more and a plate-like filler, wherein the content of the fluororesin is 1 to 30 pts.mass and the content of the plate-like filler is 5 to 80 pts.mass based on 100 pts.mass of the liquid crystalline polyester.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a liquid crystal polyester resin composition having improved mechanical properties and heat resistance while maintaining slidability.

Background Art

[0002] Liquid crystal polyesters are excellent in mechanical properties such as heat resistance and rigidity, chemical resistance, dimensional accuracy, etc. Therefore, their use is expanding not only in molded product applications but also in various applications such as fibers and films. Especially in the information and communication fields such as personal computers and mobile phones, the degree of high integration, miniaturization, thinning, and low profile of components are rapidly progressing, and there are many cases where very thin wall thicknesses of 0.5 mm or less are formed. Taking advantage of the excellent moldability of liquid crystal polymers, that is, the characteristics that they have good fluidity and do not produce burrs, which other polymers do not have, their usage amount is increasing significantly.

[0003] As described above, although liquid crystal polymers have various excellent characteristics, when used as sliding parts due to the large anisotropy of molded products, damage due to wear may easily occur.

[0004] In order to solve such problems, for example, Patent Document 1 describes a method of improving the slidability of a liquid crystal polymer composition by incorporating a fluororesin into the liquid crystal polymer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when a fluororesin is contained in a liquid crystal polyester, the heat resistance of the resin composition decreases, and thus there is a case where deformation occurs when processed at a high temperature as a molded product for applications such as electric and electronic parts and automotive members. An object of the present invention is to provide a liquid crystal polyester resin composition having improved mechanical properties and heat resistance while maintaining slidability.

Means for Solving the Problems

[0007] In view of the above problems, the present inventors conducted intensive studies and as a result, found that by blending a fluororesin having a specific average particle diameter and a plate-like filler with a liquid crystal polyester, the slidability of the liquid crystal polyester resin composition is maintained while the mechanical properties and heat resistance are improved, and thus the present invention was completed.

[0008] That is, the present invention includes the following preferred embodiments. 〔1〕Formulas (I) to (IV)

Chemical formula

Advantages of the Invention

[0009] The liquid crystal polyester resin composition of the present invention has improved mechanical properties and heat resistance while maintaining slidability, and thus is suitably used for various applications such as electric and electronic parts and automotive members.

Embodiments for Carrying Out the Invention

[0010] The liquid crystal polyester used in the liquid crystal polyester resin composition of the present invention is a liquid crystal polyester that forms a thermotropic liquid crystal polyester having an anisotropic molten phase, which is called by those skilled in the art.

[0011] The properties of the anisotropic molten phase of the liquid crystal polyester can be confirmed by a normal polarization inspection method using an orthogonal polarizer, that is, by observing a sample placed on a hot stage in a nitrogen atmosphere.

[0012] As the liquid crystal polyester used in the present invention, those containing repeating units represented by the formulas (I)~(IV) are preferably used.

Chemical formula

[0013] The total amount [p + q] of the repeating unit of formula (I) and the repeating unit of formula (II) is 60 to 78 mol%, preferably 65 to 75 mol%.

[0014] The amount [p] of the repeating unit of formula (I) is preferably 55 to 77.95 mol%, more preferably 57.5 to 77.5 mol%. The amount [q] of the repeating unit of formula (II) is 0.05 to 5 mol%, preferably 0.5 to 2.5 mol%.

[0015] The amount [r] of the repeating unit of formula (III) is 11 to 20 mol%, preferably 12 to 18 mol%. The amount [s] of the repeating unit of formula (IV) is 11 to 20 mol%, preferably 12 to 18 mol%.

[0016] In the liquid crystal polyester, the content of the aromatic dioxy repeating unit represented by formula (III) and the content of the aromatic dicarbonyl repeating unit represented by formula (IV) are preferably substantially equimolar.

[0017] Specific examples of the monomer that gives the repeating unit represented by formula (I) include 4-hydroxybenzoic acid and its acylating agents, ester derivatives, acid halides, and other ester-forming derivatives.

[0018] Specific examples of the monomer that gives the repeating unit represented by formula (II) include 6-hydroxy-2-naphthoic acid and its acylating agents, ester derivatives, acid halides, and other ester-forming derivatives.

[0019] Specific examples of the monomer that provides the repeating unit represented by formula (III) include ester-forming derivatives such as hydroquinone or its acylates.

[0020] Specific examples of the monomer that provides the repeating unit represented by formula (IV) include 2,6-naphthalenedicarboxylic acid, or ester-forming derivatives thereof such as ester derivatives and acid halides.

[0021] In the liquid crystal polyester, it is preferable that the total of the composition ratios of the repeating units [p + q + r + s] is 100 mol%, but other repeating units may be further contained as long as the object of the present invention is not impaired.

[0022] Examples of the monomer that provides other repeating units constituting the liquid crystal polyester include other aromatic hydroxycarboxylic acids, other aromatic diols, other aromatic dicarboxylic acids or aromatic hydroxydicarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

[0023] Specific examples of other aromatic hydroxycarboxylic acids include, for example, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 5-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, 4'-hydroxyphenyl-3-benzoic acid, and their alkyl, alkoxy or halogen substituents, as well as ester-forming derivatives such as their acylates, ester derivatives, and acid halides.

[0024] Specific examples of other aromatic diols include, for example, aromatic diols such as resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl ether, and their alkyl, alkoxy or halogen substituents, as well as ester-forming derivatives such as their acylates.

[0025] Specific examples of other aromatic dicarboxylic acids include, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, and their alkyl, alkoxy or halogen substituents, as well as ester-forming derivatives such as their ester derivatives and acid halides.

[0026] Specific examples of hydroxyaromatic dicarboxylic acids, which are monomers that give other repeating units, include, for example, hydroxyaromatic dicarboxylic acids such as 3-hydroxy-2,7-naphthalenedicarboxylic acid, 4-hydroxyisophthalic acid, and 5-hydroxyisophthalic acid, and their alkyl, alkoxy or halogen substituents, as well as ester-forming derivatives such as their acylates, ester derivatives, and acid halides.

[0027] Specific examples of aromatic hydroxyamines, which are monomers that give other repeating units, include, for example, aromatic hydroxyamines such as 4-aminophenol, 3-aminophenol, 4-amino-1-naphthol, 5-amino-1-naphthol, 8-amino-2-naphthol, 4-amino-4'-hydroxybiphenyl, and their alkyl, alkoxy or halogen substituents, as well as ester-forming derivatives such as their acylates.

[0028] Specific examples of the aromatic diamine, which is a monomer that provides other repeating units, include, for example, aromatic diamines such as 1,4-diaminobenzene, 1,3-diaminobenzene, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, and their alkyl, alkoxy or halogen substituents, and amide-forming derivatives such as their acylates.

[0029] Specific examples of the aromatic aminocarboxylic acid, which is a monomer that provides other repeating units, include, for example, aromatic aminocarboxylic acids such as 4-aminobenzoic acid, 3-aminobenzoic acid, 6-amino-2-naphthoic acid, and their alkyl, alkoxy or halogen substituents, and ester-forming derivatives such as their acylates, ester derivatives, acid halides.

[0030] The proportion of the repeating units provided by these other monomer components is preferably 10 mol% or less in the whole repeating units.

[0031] The crystal melting temperature of the liquid crystal polyester used in the present invention is not particularly limited, but from the viewpoints of mechanical properties, heat resistance and further low-temperature processability, those of 310 to 360 °C are preferable, those of 315 to 345 °C are more preferable, those of 318 to 343 °C are further preferable, and those less than 320 to 340 °C are even more preferable.

[0032] In the present specification and claims, the "crystal melting temperature" is determined from the peak temperature of the crystal melting temperature measured at a heating rate of 20 °C / min using a differential scanning calorimeter (hereinafter abbreviated as DSC). More specifically, after observing the endothermic peak temperature (Tm1) observed when measuring a sample of the liquid crystal polyester under heating conditions of 20 °C / min from room temperature, the sample is held at a temperature 20 to 50 °C higher than Tm1 for 10 minutes, and then, after cooling the sample to room temperature under cooling conditions of 20 °C / min, the endothermic peak observed when measuring again under heating conditions of 20 °C / min is observed, and the temperature indicating the peak top is defined as the crystal melting temperature of the liquid crystal polyester. As the measuring instrument, for example, Exstar6000 manufactured by Seiko Instruments Inc. can be used.

[0033] The liquid crystal polyester used in the present invention has a melt viscosity measured at a shear rate of 1000 s -1 under the condition of crystal melting temperature + 30 °C using a capillary rheometer (Capillograph 1D manufactured by Toyo Seiki Seisaku-sho, Ltd.) with a capillary of 0.7 mmφ × 10 mm, preferably 1 to 1000 Pa·s, and more preferably 5 to 300 Pa·s.

[0034] Hereinafter, a method for producing the liquid crystal polyester will be described.

[0035] There is no particular limitation on the method for producing the liquid crystal polyester used in the present invention, and known polycondensation methods for forming ester bonds and the like composed of the above monomer combinations, such as the melt acidolysis method and the slurry polymerization method, can be used.

[0036] The melt acidolysis method is a method preferable for use in the method for producing the liquid crystal polyester used in the present invention. In this method, first, the monomers are heated to form a melt of the reactants, and then the reaction is continued to obtain a melt polymer. In addition, a vacuum may be applied to facilitate the removal of volatile substances (for example, acetic acid, water, etc.) by-produced in the final stage of condensation.

[0037] The slurry polymerization method is a method of reacting a polymerizable monomer in the presence of a heat exchange fluid, and the solid product is obtained in a state suspended in the heat exchange medium.

[0038] In both the melt acidolysis method and the slurry polymerization method, the polymerizable monomer component used in producing the liquid crystal polyester is, at normal temperature, in a modified form in which the hydroxyl group and / or amino group is acylated, that is, used in the reaction as a lower acyl compound. It is also possible.

[0039] The lower acyl group preferably has 2 to 5 carbon atoms, more preferably 2 or 3 carbon atoms. In a preferred embodiment of the present invention, the acetylated product of the polymerizable monomer is used in the reaction.

[0040] As the lower acyl compound of the polymerizable monomer, those separately acylated and pre-synthesized may be used, or an acylating agent such as acetic anhydride may be added to the polymerizable monomer during the production of the liquid crystal polyester to generate it in the reaction system.

[0041] In either the melt acidolysis method or the slurry polymerization method, the polycondensation reaction is preferably carried out at a temperature of 150 to 400 °C, preferably 250 to 370 °C, under normal pressure and / or reduced pressure, and a catalyst may be used if necessary.

[0042] Specific examples of the catalyst include organotin compounds such as dialkyltin oxide (for example, dibutyltin oxide) and diaryltin oxide; titanium dioxide; antimony trioxide; organotitanium compounds such as alkoxytitanium silicate and titanium alkoxide; alkali and alkaline earth metal salts of carboxylic acids (for example, sodium acetate and potassium acetate); inorganic acid salts (for example, potassium sulfate); gaseous acid catalysts such as Lewis acids (for example, boron trifluoride) and hydrogen halides (for example, hydrogen chloride).

[0043] When using a catalyst, the amount of the catalyst is preferably 1 to 1000 ppm, more preferably 2 to 100 ppm, based on the total amount of the polymerizable monomer.

[0044] The liquid crystal polyester obtained by such a polycondensation reaction is usually processed into pellets, flakes, or powder after being withdrawn from the polymerization reaction tank in a molten state, and then subjected to melt-kneading with other components.

[0045] The liquid crystal polyester in the form of pellets, flakes, or powder may be heat-treated in a substantially solid state under reduced pressure, under vacuum, or in an atmosphere of an inert gas such as nitrogen or helium for the purpose of increasing the molecular weight and improving the heat resistance.

[0046] From the viewpoint of improving slidability, the liquid crystal polyester resin composition of the present invention contains a fluororesin in addition to the above liquid crystal polyester. The average particle diameter of the fluororesin is 25 μm or more. When the average particle diameter is less than 25 μm, it is difficult to achieve both the retention of mechanical strength and heat resistance and the resistance to sliding wear. Since it is easy to achieve both, the average particle diameter is preferably 30 to 80 μm, more preferably 33 to 70 μm. In this specification, the average particle diameter refers to the volume-based median diameter (median diameter) measured by the laser diffraction / scattering particle size distribution measurement method.

[0047] Examples of the fluororesin used in the present invention include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), polyvinylidene fluoride (PVDF), polyvinyl fluoride, tetrafluoroethylene·ethylene copolymer, tetrafluoroethylene·perfluoropropylene copolymer, tetrafluoroethylene·perfluoroalkyl vinyl ether copolymer, fluoroethylene·vinyl ether copolymer, polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene·ethylene copolymer, fluoroolefin·acrylate copolymer, and tetrafluoroethylene·perfluorodioxole copolymer. Among these, PTFE is preferred from the viewpoint of improving the slidability of the liquid crystal polyester resin composition.

[0048] In the liquid crystal polyester resin composition of the present invention, the content of the above-mentioned fluororesin is 1 to 30 parts by mass, preferably 2 to 29 parts by mass, more preferably 3 to 28 parts by mass, and still more preferably 5 to 27 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. By the content of the fluororesin being within the above range, while maintaining the slidability of the liquid crystal polyester resin composition, the mechanical properties and heat resistance can be improved.

[0049] In the liquid crystal polyester resin composition of the present invention, within a range not impairing the object of the present invention, in addition to the above-mentioned fluororesin, other resin components may be further contained. Examples of other resin components include thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether and its modified products, polysulfone, polyethersulfone, polyetherimide, polyamideimide, etc., and thermosetting resins such as phenol resin, epoxy resin, polyimide resin, etc. Other resin components can be contained alone or in combination of two or more.

[0050] The content of other resin components is not particularly limited and may be appropriately determined according to the use and purpose of the liquid crystal polyester resin composition. Typically, the total content of other resins with respect to 100 parts by mass of the liquid crystal polyester is preferably added in the range of 0.1 to 100 parts by mass, more preferably 0.2 to 80 parts by mass.

[0051] The liquid crystal polyester resin composition of the present invention contains a plate-like filler in addition to the above-mentioned liquid crystal polyester and fluororesin from the viewpoints of slidability, mechanical properties and heat resistance.

[0052] Examples of the plate-like filler used in the present invention include silicates such as talc, mica, kaolin, clay, vermiculite, feldspar powder, acid clay, waxstone clay, sericite, sillimanite, bentonite, glass flakes, slate powder, and silane; carbonates such as calcium carbonate, chalk, barium carbonate, magnesium carbonate, and dolomite; sulfates such as barite powder, precipitated calcium sulfate, calcined gypsum, and barium sulfate; hydroxides such as hydrated alumina; oxides such as alumina, antimony oxide, magnesia, plate-like titanium oxide, zinc white, silica, silica sand, quartz, white carbon, and diatomaceous earth; sulfides such as molybdenum disulfide; and plate-like wollastonite. These can be used alone or in combination of two or more. Among these, from the viewpoint of improving the mechanical properties and heat resistance of the liquid crystal polyester resin composition, talc, mica, and kaolin are preferred.

[0053] The content of the plate-like filler in the liquid crystal polyester resin composition of the present invention is 5 to 80 parts by mass, preferably 7 to 78 parts by mass, more preferably 10 to 76 parts by mass, and still more preferably 15 to 75 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. By the content of the plate-like filler being within the above range, the abrasion resistance can be further improved.

[0054] In the liquid crystal polyester resin composition of the present invention, in addition to the above-mentioned plate-like filler, other fibrous or granular inorganic fillers or organic fillers may be contained within a range not impairing the effects of the present invention.

[0055] Examples of other fibrous fillers include, for example, milled glass, silica alumina fiber, alumina fiber, carbon fiber, aramid fiber, polyarylate fiber, polybenzimidazole fiber, potassium titanate whisker, aluminum borate whisker, acicular titanium oxide, calcium silicate such as wollastonite, zonnolite, calcium titanate, aluminum borate, acicular calcium carbonate, acicular titanium oxide, and tetrapot type zinc oxide. These can be used alone or in combination of two or more.

[0056] Examples of other granular fillers include calcium carbonate, glass beads, etc., and these can be used alone or in combination of two or more kinds.

[0057] When the liquid crystal polyester resin composition of the present invention contains an inorganic filler or an organic filler other than the plate-like filler, the content thereof is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. If the content of these other fillers exceeds the above upper limit value, the moldability tends to decrease and the thermal stability tends to deteriorate.

[0058] In addition, the liquid crystal polyester resin composition of the present invention can contain other additives other than those described above as long as the effects of the present invention are not impaired.

[0059] Examples of other additives include lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid metal salts (where the higher fatty acid means, for example, those having 10 to 25 carbon atoms), release improvers such as polysiloxanes, colorants such as dyes, pigments, carbon black, flame retardants, antistatic agents, surfactants, phosphorus-based antioxidants, phenolic antioxidants, sulfur-based antioxidants, etc. as antioxidants, weathering agents, heat stabilizers, neutralizing agents, etc. These additives may be used alone or in combination of two or more kinds.

[0060] Regarding additives having an external lubricant effect such as higher fatty acids, higher fatty acid esters, and higher fatty acid metal salts, when molding the liquid crystal polyester resin composition, they may be adhered to the surface of the pellets of the liquid crystal polyester resin composition in advance.

[0061] The content of these other additives is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. If the content of these other additives exceeds the above upper limit value, the moldability tends to decrease and the thermal stability tends to deteriorate.

[0062] A liquid crystal polyester, a fluororesin, and a plate-shaped filler, and if desired, other resin components, other inorganic fillers and / or organic fillers, other additives, etc. are blended in a predetermined composition, and melt-kneaded using a Banbury mixer, a kneader, a single-screw or twin-screw extruder, etc., whereby the liquid crystal polyester resin composition of the present invention can be obtained.

[0063] The liquid crystal polyester resin composition of the present invention thus obtained is molded or processed by a known molding method using an injection molding machine, an extruder, etc., and a desired molded product can be obtained.

[0064] In the bending test using an ASTM No. 4 bending test piece with a thickness of 3.2 mm, the bending strength of the liquid crystal polyester resin composition of the present invention is preferably 110 MPa or more, more preferably 115 MPa or more, still more preferably 120 MPa or more, and the bending elastic modulus is preferably 8.0 GPa or more, more preferably 8.5 GPa or more. The upper limit value of the above bending strength is not particularly limited, but is, for example, 200 MPa. Also, the upper limit value of the above bending elastic modulus is not particularly limited, but is, for example, 20 GPa. Therefore, the liquid crystal polyester resin composition of the present invention has the above bending strength, for example, 110 to 200 MPa, 120 to 180 MPa, etc., and the above bending elastic modulus, for example, 8.0 to 20 GPa, 8.5 to 18 GPa, etc.

[0065] In the measurement based on ASTM D638 using an ASTM No. 4 dumbbell test piece with a thickness of 3.2 mm, the tensile elastic modulus of the liquid crystal polyester resin composition of the present invention is preferably 10 GPa or more, more preferably 11 GPa or more. The upper limit value of the above tensile elastic modulus is not particularly limited, but is, for example, 20 GPa. Therefore, the liquid crystal polyester resin composition of the present invention has the above tensile elastic modulus, for example, 10 to 20 GPa, 11 to 18 GPa, etc. A resin composition having a tensile elastic modulus within the above range exhibits high strength and can be a molded product that is difficult to deform in repeated use.

[0066] In the measurement in accordance with ASTM D638 using an ASTM No. 4 dumbbell test piece with a thickness of 3.2 mm, the tensile elongation of the liquid crystal polyester resin composition of the present invention is preferably 2.5% or less, more preferably 2.0% or less. The lower limit value of the above tensile elongation is not particularly limited, but is, for example, 0.1%. Therefore, in the liquid crystal polyester resin composition of the present invention, the above tensile elongation is, for example, 0.1 to 2.5%, 0.3 to 2.0%, etc.

[0067] The liquid crystal polyester resin composition of the present invention has excellent slidability. In this specification, the slidability can be evaluated as the coefficient of kinetic friction, and the preferred coefficient of kinetic friction is 0.33 or less, more preferably 0.31 or less, and even more preferably 0.30 or less. When the coefficient of kinetic friction exceeds the above upper limit value, the slidability tends to be insufficient. The details of the method for measuring the coefficient of kinetic friction are as described in the examples.

[0068] The liquid crystal polyester resin composition of the present invention has excellent heat resistance. In this specification, the heat resistance can be evaluated as the amount of dent at high temperature, and the preferred amount of dent at high temperature is 15 μm or less, more preferably 14 μm or less, and even more preferably 13 μm or less. When the amount of dent at high temperature exceeds the above upper limit value, the heat resistance tends to be insufficient. The details of the method for measuring the amount of dent at high temperature are as described in the examples.

[0069] According to the liquid crystal polyester resin composition of the present invention, since it exhibits improved mechanical properties and heat resistance while maintaining slidability, it is suitably used for automobile members such as instrument panels, door panels, door trims, middle boards, door ornaments, cover seat rear trays, truck covers, service hole covers, pillars, scuff plates, center consoles, cup holders, and column covers.

Examples

[0070] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples. The measurement and evaluation of the flexural strength, flexural modulus, tensile modulus, tensile elongation, amount of indentation at high temperature, and coefficient of dynamic friction in the examples were carried out by the methods described below.

[0071] 〈Flexural Strength, Flexural Modulus〉 Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), injection molding was carried out at a cylinder temperature of the crystal melting temperature + 20 to 40 °C and a mold temperature of 70 °C to produce an ASTM No. 4 flexure test piece with a thickness of 3.2 mm. The flexure test was performed as a three-point flexure test using an INSTRON5567 (universal testing machine manufactured by Instron Japan Co., Ltd.) at a span distance of 40.0 mm and a compression speed of 1.3 mm / min.

[0072] 〈Tensile Modulus, Tensile Elongation〉 Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), injection molding was carried out at a cylinder temperature of the crystal melting temperature + 20 to 40 °C and a mold temperature of 70 °C to produce an ASTM No. 4 dumbbell test piece with a thickness of 3.2 mm. The tensile modulus and tensile elongation were measured in accordance with ASTM D638 using an INSTRON5567 (universal testing machine manufactured by Instron Japan Co., Ltd.) with a contact type extensometer having a gauge length of 25 mm, a test speed of 5 mm / min, and a chuck distance of 64 mm.

[0073] 〈High Temperature Indentation Test〉 Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), injection molding was carried out at a cylinder temperature of the crystal melting temperature + 20 to 40 °C and a mold temperature of 70 °C to produce an ASTM No. 4 flexure test piece with a thickness of 3.2 mm, and a plate-like test piece (length 10 mm × width 4.5 mm × thickness 3.2 mm) was produced by cutting. The high temperature indentation test was carried out using a thermomechanical analyzer (TMA7100C manufactured by Hitachi High-Technologies Corporation) at 270 °C with a load of 1000 mN applied in the thickness direction of the test piece, and the indentation amount (μm) in the thickness direction of the test piece was measured.

[0074] 〈Coefficient of Dynamic Friction〉 Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), injection molding was carried out at a cylinder temperature of the crystal melting temperature + 20 to 40 °C and a mold temperature of 70 °C to produce a plate-shaped test piece (length 80 mm × width 80 mm × thickness 1.0 mm). The dynamic friction coefficient was measured using a surface property measuring machine (TYPE: 14FW manufactured by Shin-Tech Co., Ltd.) equipped with a SUS304 indenter (manufactured by Teroka Co., Ltd.) at a sliding speed of 1200 mm / min, a sliding distance of 10.0 mm (one-way), a sliding frequency of 1000 times (round trip), and an indenter load of 1000 gf to measure the dynamic friction coefficient during reciprocating sliding. The dynamic friction coefficient is the value obtained by calculating the average value of the dynamic friction coefficients from the 301st to 1000th times.

[0075] Hereinafter, in the examples and comparative examples, the following abbreviations represent the following compounds. POB: p-Hydroxybenzoic acid BON6: 6-Hydroxy-2-naphthoic acid HQ: Hydroquinone NDA: 2,6-Naphthalenedicarboxylic acid BP: 4,4'-Dihydroxybiphenyl TPA: Terephthalic acid

[0076] [Synthesis Example 1 (LCP-1)] Into a 2 L reaction vessel equipped with a stirring device with a torque meter and a distillation tube, 641.9 g (71.5 mol%) of POB, 30.6 g (2.5 mol%) of BON6, 93.0 g (13 mol%) of HQ, and 182.7 g (13 mol%) of NDA were charged, and further 1.03 times the molar amount of acetic anhydride based on the total molar amount of the hydroxyl groups of all the monomers was charged, and deacetic acid polymerization was carried out under the following conditions.

[0077] Under a nitrogen gas atmosphere, the temperature was raised from room temperature to 145 °C in 1 hour and held at the same temperature for 30 minutes. Then, while distilling off the by-produced acetic acid, the temperature was raised to 345 °C over 7 hours, and then the pressure was reduced to 10 mmHg over 80 minutes. When a predetermined torque was shown, the polymerization reaction was terminated, the contents of the reaction vessel were taken out, and pellets of the liquid crystal polyester resin (LCP-1) were obtained by a pulverizer. The amount of acetic acid distilled off during polymerization was almost the theoretical value. The crystal melting temperature (Tm) of the obtained pellets was 321 °C.

[0078] [Synthesis Example 2 (LCP-2)] Into a 2 L reaction vessel equipped with a stirring device with a torque meter and a distillation tube, 314.2 g (35 mol%) of POB, 61.2 g (5 mol%) of BON6, 169.4 g (14 mol%) of BP, 114.5 g (16 mol%) of HQ, and 323.9 g (30 mol%) of TPA were charged. Further, acetic anhydride in a molar amount 1.03 times the amount of hydroxyl groups (mol) of all the monomers was charged, and deacetylation polymerization was carried out under the following conditions.

[0079] The temperature was raised from room temperature to 145 °C over 1 hour under a nitrogen gas atmosphere and held at the same temperature for 30 minutes. Then, while distilling off the by-produced acetic acid, the temperature was raised to 350 °C over 7.5 hours, and then the pressure was reduced to 5 mmHg over 80 minutes. When a predetermined torque was shown, the polymerization reaction was terminated, the content was taken out from the reaction vessel, and pellets of the liquid crystal polyester resin (LCP-2) were obtained by a pulverizer. The amount of acetic acid distilled off during polymerization was almost the same as the theoretical value. The crystal melting temperature (Tm) of the obtained pellets was 337 °C.

[0080] The fluororesins and plate-like fillers used in the following examples and comparative examples are shown. 〈Fluororesin〉 FR1: Manufactured by Kitamura Co., Ltd., PTFE "KT-300M" (average particle diameter: 40 μm) FR2: Manufactured by Kitamura Co., Ltd., PTFE "KT-400M" (average particle diameter: 33 μm) FR3: Manufactured by Kitamura Co., Ltd., PTFE "KTL-610" (average particle diameter: 12 μm) FR4: Manufactured by Daikin Industries, Ltd., PTFE "L5-F" (average particle diameter: 5 μm) 〈Plate-like filler〉 Talc: Manufactured by Nippon Talc Co., Ltd., "Rose K" Mica: Manufactured by Yamaguchi Mica Co., Ltd., "AB-25S" Kaolin: Manufactured by Imerys Minerals Japan Co., Ltd., "SB 100S" 〈Granular filler〉 Calcium carbonate: Manufactured by Maruo Calcium Co., Ltd., "KRS1" <Fibrous filler> Glass fiber: manufactured by CPIC, "ECS3010A"

[0081] Examples 1 to 6 and Comparative Examples 1 to 8 The LCPs synthesized in Synthesis Examples 1 and 2, the above fluororesin, and the above filler were blended so as to have the contents (parts by mass) shown in Table 1, and melt-kneaded at 350°C using a twin-screw extruder (TEX-30 manufactured by Nippon Steel Corporation) to obtain pellets of the liquid crystal polyester resin composition. By the above method, the flexural strength, flexural modulus, tensile modulus, tensile elongation, high-temperature indentation amount, and coefficient of kinetic friction were measured and evaluated. The results are shown in Table 1.

[0082] As shown in Table 1, all of the liquid crystal polyester resin compositions of Examples 1 to 6 were excellent in mechanical properties and heat resistance while maintaining slidability.

[0083] On the other hand, as shown in Table 1, a decrease was confirmed in any of the slidability, mechanical properties, and heat resistance of the liquid crystal polyester resin compositions of Comparative Examples 1 to 8.

[0084] [Table 1]

Claims

1. Formulas (I) to (IV) 【Chemical 1】 [wherein p, q, r, and s are each the composition ratio (mol%) of each repeating unit in the liquid crystal polyester, and satisfy the following conditions: 60 ≤ p + q ≤ 78, 0.05 ≤ q ≤ 5, 11 ≤ r ≤ 20, and 11 ≤ s ≤ 20] A liquid crystal polyester containing repeating units represented by, A fluororesin having an average particle diameter of 25 μm or more, A plate-shaped filler And a liquid crystal polyester resin composition in which the content of the fluororesin is 1 to 30 parts by mass and the content of the plate-shaped filler is 5 to 80 parts by mass with respect to 100 parts by mass of the liquid crystal polyester.

2. The liquid crystal polyester resin composition according to claim 1, wherein the fluororesin is polytetrafluoroethylene.

3. The liquid crystal polyester resin composition according to claim 1 or 2, wherein the plate-shaped filler is at least one selected from the group consisting of talc, mica, and kaolin.

4. The liquid crystal polyester resin composition according to any one of claims 1 to 3, wherein when a load of 1000 mN is applied in the thickness direction of a plate-shaped test piece having a length of 10 mm, a width of 4.5 mm, and a thickness of 3.2 mm at 270 °C, the amount of dent is 15 μm or less.

5. A molded article composed of the liquid crystal polyester resin composition according to any one of claims 1 to 4.

6. The molded article is a component constituting one selected from the group consisting of an instrument panel, a door panel, a door trim, a middle board, a door ornament, a cover seat rear under tray, a truck cover, a service hole cover, a pillar, a scuff plate, a center console, a cup holder, and a column cover. The molded article according to claim 5.

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