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 (III) [wherein, Ar1 and Ar2 each represent one or more divalent aromatic groups, p, q and r are composition ratios (mol%) of each repeating unit in the liquid crystal polyester, respectively and satisfy the following conditions: 35≤p≤90, 5≤q≤30 and 5≤r≤30], 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., and 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 is rapidly progressing, and there are many cases where a very thin wall thickness part of 0.5 mm or less is 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, the amount of their use is increasing significantly.

[0003] As described above, although liquid crystal polymers have various excellent properties, 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, when processed at a high temperature as a molded product for applications such as electric and electronic parts and automotive members, it may deform. 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 completed the present invention.

[0008] That is, the present invention includes the following preferred embodiments. [1] Liquid crystal polyesters containing repeating units represented by formulas (I) to (III)

Chemical formula

[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. [Modes 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 anisotropic melt phase, which is known to those skilled in the art.

[0011] The properties of the anisotropic molten phase of the liquid crystal polyester can be confirmed by a conventional polarization inspection method using crossed polarizers, that is, by observing a sample placed on a hot stage under a nitrogen atmosphere.

[0012] As the liquid crystal polyester used in the present invention, those containing repeating units represented by formulas (I) to (III) are preferably used. [Chemical formula] [In the formula, Ar 1 and Ar 2 each represent one or more divalent aromatic groups, and p, q, and r are the composition ratios (mol%) of each repeating unit in the liquid crystal polyester, respectively, and satisfy the following conditions: 35 ≤ p ≤ 90, 5 ≤ q ≤ 30, and 5 ≤ r ≤ 30.]

[0013] The composition ratio p according to formula (I) is 35 to 90 mol%, preferably 40 to 85 mol%, more preferably 45 to 80 mol%, and even more preferably 50 to 65 mol%.

[0014] The composition ratio q according to formula (II) and the composition ratio r according to formula (III) are each 5 to 30 mol%, preferably 7.5 to 30 mol%, more preferably 10 to 27.5 mol%, and even more preferably 17.5 to 25 mol%. It is preferable that q and r are in equimolar amounts.

[0015] In the above repeating units, for example, when Ar 1 (or Ar 2 ) represents two or more divalent aromatic groups, it means that the repeating unit represented by formula (II) (or (III)) contains two or more types according to the types of divalent aromatic groups in the liquid crystal polyester. In this case, the composition ratio q according to formula (II) (or the composition ratio r according to formula (III)) represents the total composition ratio of two or more repeating units.

[0016] Specific examples of the monomer that provides the repeating unit represented by formula (I) include 6-hydroxy-2-naphthoic acid, and ester-forming derivatives thereof such as acylates, ester derivatives, and acid halides.

[0017] Specific examples of the monomer that provides the repeating unit represented by formula (II) include, for example, hydroquinone, resorcin, 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, etc., which are aromatic diols, and alkyl, alkoxy or halogen substituents thereof, and ester-forming derivatives such as acylates thereof.

[0018] Specific examples of the monomer that provides the repeating unit represented by formula (III) include, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, etc., which are aromatic dicarboxylic acids, and alkyl, alkoxy or halogen substituents thereof, and ester-forming derivatives such as ester derivatives and acid halides thereof.

[0019] Among them, as the liquid crystal polyester, Ar related to the repeating units represented by formula (II) and formula (III) 1 and Ar 2 are preferably used, which independently of each other contain one or more selected from the group consisting of aromatic groups represented by formula (1) to (4).

Chemical formula

[0020] Among these, as the repeating unit represented by the formula (II), the aromatic groups represented by the formulas (1) and (3) are more preferable because they can easily adjust the reactivity during polymerization and the mechanical properties, heat resistance, crystal melting temperature, and moldability of the resulting liquid crystal polyester to appropriate levels. Examples of the monomers that provide these repeating units include 4,4'-dihydroxybiphenyl, hydroquinone, and their ester-forming derivatives.

[0021] Further, as the repeating unit represented by the formula (III), the aromatic group represented by the formula (1) is more preferable because it can easily adjust the mechanical properties, heat resistance, crystal melting temperature, and moldability of the resulting liquid crystal polyester to appropriate levels. Examples of the monomers that provide these repeating units include terephthalic acid and its ester-forming derivatives.

[0022] Furthermore, as the liquid crystal polyester, those containing at least two kinds of repeating units according to the formulas (1) and (3) in the repeating unit represented by the formula (II), and the repeating unit according to the formula (3) is preferably contained in an amount of 80 to 99.9 mol%, more preferably 85 to 99 mol%, still more preferably 90 to 98 mol% in 100 mol% of the repeating unit represented by the formula (II) are particularly preferably used.

[0023] In the liquid crystal polyester of the present invention, it is preferable that the total [p + q + r] of the composition ratios of the repeating units is 100 mol%, but other repeating units may be further contained within a range that does not impair the object of the present invention.

[0024] Examples of the monomers that provide other repeating units include other aromatic hydroxycarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic hydroxydicarboxylic acids, aliphatic diols, aliphatic dicarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

[0025] Specific examples of other aromatic hydroxycarboxylic acids include, for example, 4-hydroxybenzoic acid, 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, acid halides, etc.

[0026] 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.

[0027] 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, acid halides, etc.

[0028] Specific examples of aromatic hydroxy dicarboxylic acids which are monomers giving 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, acid halides, etc.

[0029] Specific examples of the aromatic hydroxyamine, which is a monomer that provides 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, and ester-forming derivatives such as acylates thereof.

[0030] 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 acylates thereof.

[0031] 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 acylates, ester derivatives, acid halides thereof.

[0032] The proportion of the composition ratio of the repeating units provided by these other monomer components is preferably 10 mol% or less in the whole repeating units.

[0033] 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 preferred, those of 315 to 355 °C are more preferred, those of 318 to 350 °C are further preferred, and those of less than 320 to 340 °C are even more preferred.

[0034] In the present specification and claims, the "crystalline melting temperature" is determined from the crystalline melting peak 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 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 crystalline melting temperature of the liquid crystal polyester. As the measuring instrument, for example, Exstar6000 manufactured by Seiko Instruments Inc. can be used.

[0035] 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 the crystalline melting temperature + 30°C using a capillary rheometer (Capillograph 1D manufactured by Toyo Seiki Co., Ltd.) with a capillary of 0.7 mmφ × 10 mm, preferably 1 to 1000 Pa·s, and more preferably 5 to 300 Pa·s.

[0036] Hereinafter, the method for producing the liquid crystal polyester used in the present invention will be described. 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.

[0037] The melt acidolysis method is a method suitable 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 reaction substances, and then the reaction is continued to obtain a molten polyester. 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.

[0038] 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 of being suspended in the heat exchange medium.

[0039] In both the melt acidolysis method and the slurry polymerization method, the polymerizable monomer component used in producing the liquid crystal polyester can also be subjected to the reaction as a modified form in which the hydroxyl group is acylated at normal temperature, that is, a lower acyl compound. The lower acyl group preferably has 2 to 5 carbon atoms, and more preferably has 2 or 3 carbon atoms. In a preferred embodiment of the present invention, the acetylated product of the polymerizable monomer is subjected to 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 both the melt acidolysis method and 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 as 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; organic titanium compounds such as alkoxytitanium silicate and titanium alkoxide; alkali and alkaline earth metal salts of carboxylic acids (for example, sodium acetate, 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 pellet-shaped, flake-shaped, or powder-shaped liquid crystal polyester 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. If 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 wear resistance against sliding. 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 preferable 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, the mechanical properties and heat resistance can be improved while maintaining the slidability of the liquid crystal polyester resin composition.

[0049] In the liquid crystal polyester resin composition of the present invention, other resin components may be further contained in addition to the above-mentioned fluororesin within a range that does not impair the object of the present invention. Examples of other resin components include thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether and its modified products, polysulfone, polyethersulfone, polyetherimide, polyamideimide, and thermosetting resins such as phenol resin, epoxy resin, and polyimide resin. 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 flake, 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, talc, mica, and kaolin are preferred from the viewpoints of improving the mechanical properties and heat resistance of the liquid crystal polyester resin composition.

[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, needle-like titanium oxide, calcium silicate such as wollastonite, zonnolite, calcium titanate, aluminum borate, needle-like calcium carbonate, needle-like 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, for example, 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) which are lubricants, polysiloxanes which are mold release improvers, dyes, pigments, carbon black which are colorants, flame retardants, antistatic agents, surfactants, phosphorus-based antioxidants, phenolic antioxidants, sulfur-based antioxidants which are 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, they may be adhered to the surface of the pellets of the liquid crystal polyester resin composition in advance when molding the liquid crystal polyester resin composition.

[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 can be molded or processed by a known molding method using an injection molding machine, an extruder, etc. to obtain a desired molded product.

[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 150 MPa or more, more preferably 155 MPa or more, and the bending elastic modulus is preferably 10.0 GPa or more, more preferably 10.5 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, 150 to 200 MPa, 155 to 190 MPa, etc., and the above bending elastic modulus, for example, 10.0 to 20 GPa, 10.5 to 18 GPa, etc.

[0065] In the measurement conforming to 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 can exhibit 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 2.0% or less, more preferably 1.5% 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 2.0%, 0.3 to 1.5%, 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 0.15 or less, more preferably 0.14 or less, and even more preferably 0.13 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 4.0 μm or less, more preferably 3.5 μm or less, and even more preferably 3.0 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, while maintaining the slidability, it exhibits improved mechanical properties and heat resistance, so it is suitably used for automobile members such as instrument panels, door panels, door trims, middle boards, door ornaments, cover seat trays, truck covers, service hole covers, pillars, scuff plates, center consoles, cup holders, and column covers.

Examples

[0070] Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples. The measurement and evaluation of the flexural strength, flexural modulus, high-temperature indentation amount, 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 flexural test piece with a thickness of 3.2 mm. The flexural test was performed as a three-point flexural test using an INSTRON5567 (universal testing machine manufactured by Instron Japan K.K.) 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 K.K.) with a contact-type extensometer having a gauge length of 25 mm under the conditions of 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 flexural test piece with a thickness of 3.2 mm, and a plate-shaped 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) by applying a load of 1000 mN in the thickness direction of the test piece at 270 °C and measuring the indentation amount (μm) in the thickness direction of the test piece.

[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. BON6: 6-Hydroxy-2-naphthoic acid HQ: Hydroquinone BP: 4,4'-Dihydroxybiphenyl TPA: Terephthalic acid POB: p-Hydroxybenzoic 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, 660.5 g (54.0 mol%) of BON6, 254.2 g (21.0 mol%) of BP, 14.3 g (2.0 mol%) of HQ, and 248.3 g (23.0 mol%) of TPA were charged. Further, acetic anhydride in an amount 1.03 times the 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 150 °C over 1 hour and held at 150 °C for 60 minutes. Then, while distilling off the by-produced acetic acid, the temperature was raised to 350 °C over 7 hours and then reduced to 10 mmHg over 90 minutes. The polymerization reaction was terminated when a predetermined torque was shown, the content was taken out from the reaction vessel, and pellets of liquid crystal polyester (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 338 °C, and the melt viscosity was 23 Pa·s.

[0078] [Synthesis Example 2 (LCP-2)] A 2 L reaction vessel equipped with a stirring device with a torque meter and a distillation tube was charged with 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. Further, acetic anhydride in a molar amount 1.03 times the amount of hydroxyl groups of all the monomers (mol) 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-shaped 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-shaped 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"

[0081] Examples 1 to 4 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 kneading was carried out 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 dent 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 4 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 (III) 【Chemical 1】 [wherein Ar １ and Ar ２ each represents one or more divalent aromatic groups, and p, q, and r are respectively the composition ratios (mol%) of each repeating unit in the liquid crystal polyester and satisfy the following conditions: 35 ≤ p ≤ 90, 5 ≤ q ≤ 30, and 5 ≤ r ≤ 30] A liquid crystal polyester containing a repeating unit represented by the formula, A fluororesin having an average particle diameter of 25 μm or more, A plate-shaped filler And a liquid crystal polyester resin composition containing 1 to 30 parts by mass of the fluororesin and 5 to 80 parts by mass of the plate-shaped filler with respect to 100 parts by mass of the liquid crystal polyester.

2. Formula (II) and / or formula (III) is Ar １ and Ar ２ are, independently of one another, formulae (1) to (4) [Chemical 2] The liquid crystal polyester resin composition according to claim 1, comprising one or more kinds of repeating units that are aromatic groups selected from the group consisting of

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

4. The liquid crystal polyester resin composition according to any one of claims 1 to 3, wherein the plate-shaped filler is one or more selected from the group consisting of talc, mica, and kaolin.

5. The liquid crystal polyester resin composition according to any one of claims 1 to 4, 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 indentation is 4.0 μm or less.

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

7. 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 6.

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