Liquid crystal polymer composition

Abstract

To provide a liquid crystal polymer composition that exhibits excellent compoundability and enhanced thermal conductivity while maintaining mechanical strength, toughness, fluidity, and heat resistance of a liquid crystal polymer.SOLUTION: A liquid crystal polymer composition of the present invention comprises a liquid crystal polymer, a plate-like filler having an aspect ratio of 3 or more, a glass fiber having an average fiber diameter of 5 to 15 μm, and a polybenzazole fiber having an average fiber diameter of 5 to 15 μm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal polymer composition that has excellent compoundability and improved thermal conductivity while maintaining the mechanical strength, toughness, fluidity, and heat resistance of a liquid crystal polymer. [Background technology]

[0002] In recent years, as electrical and electronic components have become smaller and more sophisticated, the amount of heat generated has increased, and performance degradation due to rising component temperatures has become an issue. To prevent this performance degradation, resin materials used in electrical and electronic components are required to have high heat dissipation properties, i.e., high thermal conductivity.

[0003] On the other hand, liquid crystal polymers are being used increasingly in molded products due to their excellent mechanical strength, toughness, fluidity, heat resistance, electrical insulation, chemical resistance, dimensional accuracy, etc. In particular, in the information and communications field, such as personal computers and mobile phones, there has been a rapid advancement in the high integration, miniaturization, thinning, and low profile of parts, and the use of liquid crystal polymers has increased significantly, taking advantage of their excellent moldability.

[0004] Therefore, while there is a demand for improved thermal conductivity in resin materials, if improved thermal conductivity can be achieved, particularly in liquid crystal polymers, which are widely used in electrical and electronic components, it will lead to even higher performance in these components.

[0005] Patent Document 1 proposes a thermally conductive polycarbonate resin composition containing a liquid crystal polymer, but the thermal conductivity is insufficient and the heat resistance is poor.

[0006] Patent Document 2 describes a method of improving thermal conductivity by adding plate-like fillers and powdered granular fillers of specific particle sizes to a liquid crystal polymer. However, this method involves adding large amounts of talc and boron nitride, which significantly reduces mechanical strength and makes it prone to losing toughness and heat resistance.

[0007] Therefore, there is a demand for a liquid crystal polymer composition that has excellent compoundability and improved thermal conductivity while maintaining the mechanical strength, toughness, fluidity, and heat resistance of a liquid crystal polymer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2021-31544 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-127026 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a liquid crystal polymer composition which has excellent compoundability and improved thermal conductivity while maintaining the mechanical strength, toughness, fluidity and heat resistance of a liquid crystal polymer. [Means for solving the problem]

[0010] In view of the above problems, the present inventors have conducted extensive research and have found that by blending a liquid crystal polymer with a plurality of specific fillers in specific ratios, a liquid crystal polymer composition can be obtained that has improved thermal conductivity while maintaining the properties of the liquid crystal polymer, and have thus completed the present invention.

[0011] That is, the present invention includes the following preferred embodiments. [1] A liquid crystal polymer composition containing a liquid crystal polymer, a plate-like filler having an aspect ratio of 3 or more, glass fibers having an average fiber diameter of 5 to 15 μm, and polybenzazole fibers having an average fiber diameter of 5 to 15 μm. [2] The liquid crystal polymer composition according to [1], containing 20 to 150 parts by mass of a plate-like filler, 10 to 80 parts by mass of glass fiber, and 3 to 25 parts by mass of polybenzazole fiber per 100 parts by mass of the liquid crystal polymer. [3] The liquid crystal polymer is represented by formula (I) and / or formula (II) [ka] The liquid crystal polymer composition according to [1] or [2], which is a liquid crystal polyester resin containing a repeating unit represented by the following formula: [4] The liquid crystal polymer is represented by the formula (I) and the formula (II) [ka] The liquid crystal polymer composition according to [3], which is a liquid crystal polyester resin containing a total of 90 mol % or more of repeating units represented by the following formula: [5] The liquid crystal polymer is represented by the formula (I) to the formula (IV): [ka] The liquid crystal polymer composition according to [1], which is a liquid crystal polyester resin containing a repeating unit represented by the following formula: [6] In the repeating units represented by formulae (III) to (IV), Ar1 and Ar2 are each independently represented by formulae (1) to (4): [ka] The liquid crystal polymer composition according to [5], wherein each of the repeating units is one or more types selected from aromatic groups represented by the following formula: [7] The liquid crystal polymer composition according to any one of [1] to [6], wherein the platy filler is at least one selected from the group consisting of talc, mica, alumina, boehmite, and boron nitride. [8] The liquid crystal polymer composition according to any one of [1] to [7], wherein the average particle size of the plate-like filler is 0.1 to 50 μm. [9] The liquid crystal polymer composition according to any one of [1] to [8], wherein the thermal conductivity in the flow direction of the molten resin composition during molding is 2.0 W / m·K or more.

[10] The liquid crystal polymer composition according to any one of [1] to [9], which has a flexural strength of 140 MPa or more as measured in accordance with ASTM D790.

[11] The liquid crystal polymer composition according to any one of [1] to

[10] , which has an Izod impact strength of 40 J / m or more as measured in accordance with ASTM D256.

[12] A molded article made from the liquid crystal polymer composition according to any one of [1] to

[11] .

[13] The molded article according to

[12] , wherein the minimum thickness of the molded article is 1.0 mm or less.

[14] The molded article according to

[12] or

[13] , which is a component constituting one selected from the group consisting of a connector, a switch, a relay, a capacitor, a coil, a motor, a test socket, a transformer, a camera module, and an antenna. [Effects of the Invention]

[0012] The liquid crystal polymer composition of the present invention has excellent compoundability and improved thermal conductivity while maintaining the mechanical strength, toughness, fluidity, and heat resistance of liquid crystal polymers, and is therefore suitable for use in a variety of applications requiring heat dissipation performance, such as electrical and electronic components. DETAILED DESCRIPTION OF THE INVENTION

[0013] The liquid crystal polymer (hereinafter also referred to as LCP) used in the liquid crystal polymer composition of the present invention is a polyester or polyesteramide that forms an anisotropic molten phase, and is not particularly limited as long as it is what is called a thermotropic liquid crystal polyester or a thermotropic liquid crystal polyesteramide in the relevant technical field.

[0014] The anisotropic melt phase can be confirmed by conventional polarized light examination using crossed polarizers. More specifically, the anisotropic melt phase can be confirmed by observing a sample placed on a Leitz hot stage under a nitrogen atmosphere at 40x magnification using a Leitz polarizing microscope. The liquid crystal polymer of the present invention is optically anisotropic, i.e., it transmits light when examined between crossed polarizers. If the sample is optically anisotropic, polarized light will be transmitted even when the sample is stationary.

[0015] The liquid crystal polymer used in the present invention preferably has a crystalline melting temperature measured by a differential scanning calorimeter of 220 to 380°C, more preferably 240 to 370°C, even more preferably 260 to 360°C, and particularly preferably 270 to 350°C.

[0016] If the crystalline melting temperature of the liquid crystal polymer is lower than 220°C, the heat resistance will be poor, and if it is higher than 380°C, the molding processability will tend to decrease, which is undesirable.

[0017] In this specification and claims, the term "crystalline melting temperature" refers to the peak crystalline melting temperature measured using a differential scanning calorimeter (DSC) at a heating rate of 20°C / min. More specifically, a liquid crystal polymer sample is measured at a 20°C / min heating rate from room temperature to reach an endothermic peak temperature (Tm1). The sample is then held at a temperature 20-50°C higher than Tm1 for 10 minutes, cooled to room temperature at a 20°C / min cooling rate, and then measured again at a 20°C / min heating rate to reach an endothermic peak. The temperature at the top of this peak is taken as the crystalline melting temperature of the liquid crystal polymer. For example, a Seiko Instruments Inc. Exstar 6000 or the like can be used as a measuring instrument.

[0018] Examples of polymerizable monomers constituting the structural units of the liquid crystal polymer of the present invention include aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic aminocarboxylic acids, aromatic hydroxyamines, aromatic diamines, aliphatic diols, and aliphatic dicarboxylic acids.Such polymerizable monomers may be used alone or in combination of two or more.Preferably, polymerizable monomers having at least one hydroxyl group and one carboxyl group are used.

[0019] Specific examples of aromatic hydroxycarboxylic acids include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 5-hydroxy-2-naphthoic acid, 7-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 alkyl-, alkoxy-, or halogen-substituted derivatives thereof, as well as ester-forming derivatives thereof such as acylation products, ester derivatives, and acid halides. Among these, one or more compounds selected from the group consisting of 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are preferred from the viewpoint of ease of adjusting the heat resistance, mechanical strength, and melting point of the resulting liquid crystal polymer.

[0020] Specific examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, 3,4'-dicarboxybiphenyl, and 4,4"-dicarboxyterphenyl, as well as alkyl, alkoxy, or halogen-substituted derivatives thereof, and ester-forming derivatives thereof, such as ester derivatives and acid halides. Among these, from the viewpoint of effectively enhancing the heat resistance of the resulting liquid crystal polymer, one or more compounds selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are preferred, and terephthalic acid and 2,6-naphthalenedicarboxylic acid are more preferred.

[0021] Specific examples of aromatic diols include hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl ether, and 2,2'-dihydroxybinaphthyl, as well as ester-forming derivatives thereof such as alkyl, alkoxy, or halogen-substituted derivatives and acylated derivatives thereof. Among these, from the viewpoint of excellent reactivity during polymerization, one or more compounds selected from the group consisting of hydroquinone, resorcinol, 4,4'-dihydroxybiphenyl, and 2,6-dihydroxynaphthalene are preferred, and one or more compounds selected from the group consisting of hydroquinone, 4,4'-dihydroxybiphenyl, and 2,6-dihydroxynaphthalene are more preferred.

[0022] Specific examples of aromatic aminocarboxylic acids include 4-aminobenzoic acid, 3-aminobenzoic acid, 6-amino-2-naphthoic acid, alkyl-, alkoxy-, or halogen-substituted derivatives thereof, and ester-forming derivatives thereof such as acylated products, ester derivatives, and acid halides.

[0023] Specific examples of aromatic hydroxyamines include 4-aminophenol, N-methyl-4-aminophenol, 3-aminophenol, 3-methyl-4-aminophenol, 4-amino-1-naphthol, 4-amino-4'-hydroxybiphenyl, 4-amino-4'-hydroxybiphenyl ether, 4-amino-4'-hydroxybiphenylmethane, 4-amino-4'-hydroxybiphenyl sulfide, and 2,2'-diaminobinaphthyl, as well as ester-forming derivatives thereof such as alkyl, alkoxy, or halogen-substituted derivatives thereof, and acylated derivatives thereof. Among these, 4-aminophenol is preferred from the viewpoint of easily achieving a balance between the heat resistance and mechanical strength of the resulting liquid crystal polymer.

[0024] Specific examples of aromatic diamines include amide-forming derivatives such as 1,4-phenylenediamine, 1,3-phenylenediamine, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, alkyl-, alkoxy- or halogen-substituted derivatives thereof, and acylated derivatives thereof.

[0025] Specific examples of the aliphatic diol include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and acylated derivatives thereof. Also, a polymer containing an aliphatic diol, such as polyethylene terephthalate or polybutylene terephthalate, may be reacted with the aromatic oxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, and their acylated derivatives, ester derivatives, acid halides, etc.

[0026] Specific examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, fumaric acid, maleic acid, and hexahydroterephthalic acid. Among these, oxalic acid, succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid are preferred from the viewpoint of excellent reactivity during polymerization.

[0027] The polymerizable monomers forming the structural units of the liquid crystal polymer of the present invention may contain, as other copolymerization components, dihydroxyterephthalic acid, 4-hydroxyisophthalic acid, 5-hydroxyisophthalic acid, trimellitic acid, 1,3,5-benzenetricarboxylic acid, pyromellitic acid, or alkyl, alkoxy, or halogen-substituted derivatives thereof, as well as ester-forming derivatives thereof such as acylation products, ester derivatives, and acid halides, within the scope of the present invention. The amount of these polymerizable monomers used is preferably 10 mol % or less of the total structural units constituting the liquid crystal polymer.

[0028] In the present invention, the liquid crystal polymer may contain a thioester bond, provided that the object of the present invention is not impaired. Polymerizable monomers that provide such bonds include mercapto aromatic carboxylic acids, aromatic dithiols, and hydroxy aromatic thiols. The content of these polymerizable monomers is preferably 10 mol% or less of the total structural units constituting the liquid crystal polymer.

[0029] Polymers that combine these repeating units may or may not form an anisotropic molten phase depending on the monomer structure, composition ratio, and sequence distribution of each repeating unit in the polymer. However, the liquid crystal polymers used in the present invention are limited to those that form an anisotropic molten phase.

[0030] As the liquid crystal polymer used in the liquid crystal polymer composition of the present invention, a liquid crystal polyester resin containing a repeating unit represented by formula (I) and / or formula (II) is preferably used, in terms of heat resistance, mechanical strength, and ease of adjusting the crystalline melting temperature. [ka]

[0031] Specific examples of the combination of polymerizable monomers forming the structural units of the liquid crystal polymer used in the present invention include the following. 1) 4-hydroxybenzoic acid / 6-hydroxy-2-naphthoic acid, 2) 4-hydroxybenzoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl, 3) 4-hydroxybenzoic acid / terephthalic acid / isophthalic acid / 4,4'-dihydroxybiphenyl, 4) 4-hydroxybenzoic acid / terephthalic acid / isophthalic acid / 4,4'-dihydroxybiphenyl / hydroquinone, 5) 4-hydroxybenzoic acid / terephthalic acid / hydroquinone, 6) 6-hydroxy-2-naphthoic acid / terephthalic acid / hydroquinone, 7) 4-hydroxybenzoic acid / 6-hydroxy-2-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl, 8) 6-hydroxy-2-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl, 9) 4-hydroxybenzoic acid / 6-hydroxy-2-naphthoic acid / terephthalic acid / hydroquinone, 10) 4-hydroxybenzoic acid / 6-hydroxy-2-naphthoic acid / terephthalic acid / hydroquinone / 4,4'-dihydroxybiphenyl, 11) 4-hydroxybenzoic acid / 2,6-naphthalenedicarboxylic acid / 4,4'-dihydroxybiphenyl, 12) 4-hydroxybenzoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone, 13) 4-hydroxybenzoic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone, 14) 4-hydroxybenzoic acid / 6-hydroxy-2-naphthoic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone, 15) 4-hydroxybenzoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone / 4,4'-dihydroxybiphenyl, 16) 4-hydroxybenzoic acid / terephthalic acid / 4-aminophenol, 17) 6-hydroxy-2-naphthoic acid / terephthalic acid / 4-aminophenol, 18) 4-hydroxybenzoic acid / 6-hydroxy-2-naphthoic acid / terephthalic acid / 4-aminophenol, 19) 4-hydroxybenzoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl / 4-aminophenol, 20) 4-hydroxybenzoic acid / terephthalic acid / ethylene glycol 21) 4-hydroxybenzoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl / ethylene glycol, 22) 4-hydroxybenzoic acid / 6-hydroxy-2-naphthoic acid / terephthalic acid / ethylene glycol 23) 4-hydroxybenzoic acid / 6-hydroxy-2-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl / ethylene glycol 24) 4-Hydroxybenzoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / 4,4'-dihydroxybiphenyl.

[0032] Among these, liquid crystal polymers consisting of structural units derived from polymerizable monomers 1), 9), 10), and 14) are preferred, liquid crystal polymers consisting of structural units derived from polymerizable monomers 1) and 10) are more preferred, and liquid crystal polymers consisting of structural units derived from polymerizable monomer 1) are even more preferred.

[0033] In one preferred embodiment, the liquid crystal polymer used in the liquid crystal polymer composition of the present invention is a liquid crystal polyester resin containing a total of 90 mol% or more of repeating units represented by formula (I) and formula (II), due to its excellent mechanical properties, and a liquid crystal polyester resin composed of repeating units represented by formula (I) and formula (II) is more preferred. The repeating units represented by formula (I) are preferably 50 to 90 mol%, more preferably 60 to 80 mol%, and even more preferably 70 to 75 mol%. The repeating units represented by formula (II) are preferably 10 to 50 mol%, more preferably 20 to 40 mol%, and even more preferably 25 to 30 mol%. [ka]

[0034] In another preferred embodiment, the liquid crystal polymer used in the liquid crystal polymer composition of the present invention is preferably a liquid crystal polyester resin containing repeating units represented by formulas (I) to (IV), because of its excellent fluidity and heat resistance. [ka]

[0035] Here, the repeating unit represented by formula (III) may be a plurality of types of repeating units each containing a different Ar1, and the repeating unit represented by formula (IV) may be a plurality of types of repeating units each containing a different Ar2. That is, the repeating unit represented by formula (III) may be a plurality of repeating units, such as a repeating unit having one type of Ar1 and a repeating unit having another type of Ar1, and similarly, the repeating unit represented by formula (IV) may be a plurality of repeating units, such as a repeating unit having one type of Ar2 and a repeating unit having another type of Ar2. Furthermore, the term "aromatic group" refers to an aromatic group that is a 6-membered monocyclic ring or a fused ring having two rings.

[0036] In terms of excellent fluidity and heat resistance, the total composition ratio (mol %) of the repeating units represented by formula (I) and formula (II) is preferably 30 to 80 mol %, more preferably 35 to 60 mol %. The repeating units represented by formula (II) are preferably 0.5 to 20 mol %, more preferably 1 to 17 mol %, and even more preferably 2 to 10 mol %. The repeating units represented by formula (III) and formula (IV) are each preferably 10 to 35 mol %, more preferably 20 to 32.5 mol %. The repeating units represented by formula (III) and formula (IV) are preferably in substantially equimolar amounts.

[0037] In terms of excellent fluidity and mechanical properties, it is more preferable that the repeating units represented by formulas (III) to (IV) are each independently one or more repeating units in which Ar1 and Ar2 are selected from the aromatic groups represented by formulas (1) to (4): It is particularly preferable that the repeating unit represented by formula (III) is a repeating unit in which Ar1 is an aromatic group represented by formula (1) and / or formula (3), and that the repeating unit represented by formula (IV) is a repeating unit in which Ar2 is an aromatic group represented by formula (1) and / or formula (4). [ka]

[0038] The method for producing the liquid crystal polymer used in the present invention will be described below.

[0039] There are no particular limitations on the method for producing the liquid crystal polymer used in the present invention, and the liquid crystal polymer can be obtained by subjecting a polymerizable monomer to a known polycondensation method for forming an ester bond or an amide bond, such as a melt acidolysis method or a slurry polymerization method.

[0040] The melt acidolysis method is a preferred method for preparing the liquid crystalline polymer used in the liquid crystalline polymer composition of the present invention. This method involves first heating the polymerizable monomers to form a molten solution of the reactants, followed by a polycondensation reaction to obtain a molten polymer. A vacuum may be applied to facilitate removal of volatile by-products (e.g., acetic acid, water, etc.) produced during the final stage of condensation.

[0041] Slurry polymerization is a process in which polymerizable monomers are reacted in the presence of a heat exchange fluid, resulting in a solid product suspended in the heat exchange medium.

[0042] In both the melt acidolysis method and the slurry polymerization method, the polymerizable monomer used in producing the liquid crystal polymer can also be subjected to the reaction at room temperature in a modified form in which the hydroxyl group and / or amino group is acylated, i.e., as a lower acylated product.

[0043] The lower acyl group preferably has 2 to 5 carbon atoms, more preferably 2 or 3. In a preferred embodiment of the present invention, an acetylated product of the polymerizable monomer is subjected to the reaction.

[0044] The lower acylated polymerizable monomer may be a pre-synthesized product obtained by separate acylation, or may be produced in the reaction system by adding an acylating agent such as acetic anhydride to the polymerizable monomer during the production of the liquid crystal polymer.

[0045] In either the melt acidolysis method or the slurry polymerization method, the polycondensation reaction is 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.

[0046] Specific examples of catalysts include organotin compounds such as dialkyltin oxides (e.g., dibutyltin oxide) and diaryltin oxides; titanium dioxide; antimony trioxide; organotitanium compounds such as alkoxytitanium silicates and titanium alkoxides; alkali and alkaline earth metal salts of carboxylic acids (e.g., sodium acetate and potassium acetate); and gaseous acid catalysts such as Lewis acids (e.g., boron trifluoride) and hydrogen halides (e.g., hydrogen chloride).

[0047] When a catalyst is used, the amount of the catalyst is preferably 1 to 1000 ppm, more preferably 2 to 100 ppm, based on the total amount of polymerizable monomers.

[0048] The liquid crystal polymer obtained by such a polycondensation reaction is usually extracted in a molten state from a polymerization reaction vessel, processed into pellets, flakes, or powder, and then melt-kneaded with other components.

[0049] The liquid crystal polymer in pellet, flake, or powder form may be heat-treated in a substantially solid state under reduced pressure, vacuum, or an atmosphere of an inert gas such as nitrogen or helium, in order to increase the molecular weight and improve the heat resistance.

[0050] From the viewpoints of improving thermal conductivity, mechanical strength and compoundability, the liquid crystal polymer composition of the present invention contains a platy filler, glass fiber and polybenzazole fiber in the liquid crystal polymer obtained as described above.

[0051] In the present invention, the term "platy filler" refers to a filler that has a three-dimensional shape and is disc-shaped, rectangular, rectangular, or irregularly shaped, and has two dimensions and one that is not. Specific examples include silicates such as talc, mica, graphite, dolomite, clay, glass flakes, kaolin, vermiculite, calcium silicate, aluminum silicate, feldspar powder, acid clay, rosewood clay, sericite, sillimanite, bentonite, slate powder, and silane; sulfates such as calcium carbonate, chalk, barium carbonate, magnesium carbonate, barite powder, precipitated calcium sulfate, gypsum, and barium sulfate; hydroxides such as hydrated alumina; oxides such as alumina, boehmite, antimony oxide, magnesia, titanium oxide, zinc oxide, silica, silica sand, quartz, white carbon, boron nitride, and diatomaceous earth; sulfides such as molybdenum disulfide; plate-like wollastonite; and metal powders and granules. Among these plate-like fillers, one or more selected from the group consisting of talc, mica, alumina, boehmite and boron nitride are preferred, as they have an excellent effect of improving the thermal conductivity of the liquid crystal polymer composition and the fluidity during molding, and one or more selected from the group consisting of talc, boehmite and boron nitride are even more preferred, with talc being particularly preferred.

[0052] The average particle size of the plate-like filler is preferably 0.1 to 50 μm, more preferably 2 to 40 μm, and even more preferably 5 to 30 μm. In this specification, the average particle size refers to the volume-based median value (median diameter) measured by a laser diffraction / scattering particle size distribution measurement method.

[0053] The plate-like filler contained in the liquid crystal polymer composition of the present invention has an aspect ratio of 3 or more. The aspect ratio of the plate-like filler is preferably 3 to 100, more preferably 4 to 70. The aspect ratio is the average particle diameter divided by the thickness.

[0054] The aspect ratio of the plate-like filler is measured by the method described below. Aspect ratio The sample powder was photographed using a scanning electron microscope (SEM) (Hitachi High-Tech Fielding S-4000), and the thickness of 100 primary particles of the plate-like filler was measured and the average value was used as the thickness. The aspect ratio was calculated using the following formula. Aspect ratio = average particle size of plate-like filler / thickness of plate-like filler

[0055] The plate-like filler may be treated with a known surface treatment agent before use.

[0056] In the liquid crystal polymer composition of the present invention, the content of the plate-like filler is preferably 20 to 150 parts by mass, more preferably 25 to 110 parts by mass, even more preferably 30 to 80 parts by mass, and particularly preferably 35 to 70 parts by mass, relative to 100 parts by mass of the liquid crystal polymer. If the content of the plate-like filler is less than 20 parts by mass, the thermal conductivity tends to be insufficient, and if it exceeds 150 parts by mass, the mechanical strength and toughness of the liquid crystal polymer tend to decrease.

[0057] The glass fibers used in the liquid crystal polymer composition of the present invention have a number-average fiber diameter of 5 to 15 μm, preferably 8 to 13 μm, and more preferably 10 to 12 μm. The cut fiber length is preferably 10 mm or less, more preferably 1.5 to 6 mm, and even more preferably 2 to 4 mm. The number-average fiber length of the glass fibers in the resulting liquid crystal polymer composition is preferably 50 to 600 μm, more preferably 60 to 500 μm, and even more preferably 70 to 450 μm. To obtain a liquid crystal polymer composition containing glass fibers of the desired fiber length, the melt-kneading conditions can be set according to the cut fiber length of the glass fibers used. The average fiber diameter of the glass fibers remains substantially unchanged even after melt-kneading.

[0058] The number average fiber length and average fiber diameter of the glass fibers in the liquid crystal polymer composition after melt-kneading are measured by the methods described below. <Method for measuring number average fiber length and average fiber diameter of glass fibers> The liquid crystal polymer composition containing glass fibers is completely incinerated, and the remaining glass fibers are thoroughly stirred and dispersed in a mixture of pure water and a surfactant. 1 ml of the mixture is placed on a glass plate, and the glass fibers are observed under a microscope. The number-average fiber length and average fiber diameter are determined from the measurements of 100 fibers.

[0059] The content of the glass fiber to be blended in the liquid crystal polymer composition of the present invention is 10 to 80 parts by mass, preferably 20 to 60 parts by mass, and more preferably 30 to 50 parts by mass, per 100 parts by mass of the liquid crystal polymer. If the content of the glass fiber is less than 10 parts by mass, the mechanical strength tends to be insufficient.

[0060] The polybenzazole fiber (hereinafter sometimes abbreviated as PBZ fiber) used in the liquid crystal polymer composition of the present invention is a fibrous polybenzazole resin, and refers to polybenzoxazole (PBO) homopolymer, polybenzothiazole (PBT) homopolymer, and random, sequential, or block copolymers of PBO and PBT. Among these, those containing PBO as the main component are preferred.

[0061] The PBZ fibers used in the liquid crystal polymer composition of the present invention have a number average fiber diameter of 5 to 15 μm, preferably 8 to 14 μm, and more preferably 9 to 13 μm. The cut fiber length of the PBZ fibers is preferably 0.1 mm to 5 mm. If the cut fiber length is less than 0.1 mm, the fibers are too fine and bulky, which tends to make them difficult to feed into a kneader and to deteriorate compoundability. If the cut fiber length is more than 5 mm, the fibers tend to tangle and form clumps, which tends to deteriorate compoundability.

[0062] The content of the PBZ fiber blended in the liquid crystal polymer composition of the present invention is preferably 3 to 25 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 7 to 15 parts by mass, relative to 100 parts by mass of the liquid crystal polymer. If the content of the PBZ fiber is less than 3 parts by mass, the thermal conductivity and toughness tend to be insufficient, and if it exceeds 25 parts by mass, the compoundability tends to deteriorate.

[0063] In the present invention, the liquid crystal polymer composition may contain other additives within the range that does not impair the effects of the present invention. The liquid crystal polymer composition of the present invention may contain, for example, a release improver such as a higher fatty acid, a higher fatty acid ester, a higher fatty acid amide, a higher fatty acid metal salt (here, higher fatty acid refers to one having 10 to 25 carbon atoms), polysiloxane, or fluororesin; a colorant such as carbon black, a dye, or a pigment; an antioxidant; a heat stabilizer; an ultraviolet absorber; an antistatic agent; or a surfactant. The liquid crystal polymer composition of the present invention may contain only one of these additives, or two or more of them in combination. Among these, carbon black is preferred. When the liquid crystal polymer composition of the present invention contains carbon black, the content thereof is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the liquid crystal polymer.

[0064] A substance having an external lubricant effect, such as a higher fatty acid, a higher fatty acid ester, a higher fatty acid metal salt, or a fluorocarbon surfactant, may be attached to the surface of the pellets in advance when molding the liquid crystal polymer composition of the present invention.

[0065] The total amount of other additives in the liquid crystal polymer composition is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, relative to 100 parts by mass of the liquid crystal polymer. If the total amount of other additives exceeds 10 parts by mass relative to 100 parts by mass of the liquid crystal polymer, the moldability and thermal stability of the liquid crystal polymer composition tend to decrease.

[0066] The liquid crystal polymer composition of the present invention may further contain other resin components that are moldable in the same temperature range as the liquid crystal polymer used in the present invention, provided that the objectives of the present invention are not impaired. Examples of such other resin components include thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether and modified products thereof, polysulfone, polyethersulfone, polyetherimide, and polyamideimide, as well as thermosetting resins such as phenolic resins, epoxy resins, and polyimide resins. The other resin components may be used alone or in combination of two or more. The amount of the other resin components is not particularly limited and may be determined appropriately depending on the application and purpose of the liquid crystal polymer composition. Typically, the total amount of the other resins added is 0.1 to 100 parts by weight, particularly 0.1 to 80 parts by weight, per 100 parts by weight of the liquid crystal polymer of the present invention.

[0067] The liquid crystal polymer composition of the present invention can be obtained by combining a liquid crystal polymer with a plate-like filler, glass fiber, PBZ fiber, and, if desired, other additives and other resin components, and melt-kneading the mixture to a predetermined composition using a Banbury mixer, kneader, single-screw or twin-screw extruder, etc.

[0068] The thermal conductivity of the liquid crystal polymer composition of the present invention, measured by the laser flash method, in the machine direction (MD) of a molded article made from the composition when the molten resin composition is filled into a mold during molding is preferably 2.0 W / m·K or more, more preferably 2.2 W / m·K or more, and even more preferably 2.3 W / m·K or more. Having a machine direction (MD) thermal conductivity of 2.0 W / m·K or more when the molten resin composition is filled into a mold during molding can be expected to improve the heat dissipation of various molded articles, particularly thin-walled and long molded articles. The machine direction (MD) thermal conductivity is usually 15 W / m·K or less.

[0069] The liquid crystal polymer composition of the present invention has a bending strength of preferably 140 MPa or more, more preferably 150 MPa or more, and even more preferably 160 MPa or more, in a bending test according to ASTM D790 using a strip-shaped test piece having a length of 127 mm, a width of 12.7 mm, and a thickness of 3.2 mm. The upper limit of the bending strength is not particularly limited, but is, for example, 300 MPa.

[0070] The liquid crystal polymer composition of the present invention has an Izod impact strength of preferably 40 J / m or more, more preferably 45 J / m or more, and even more preferably 50 J / m or more, in an Izod impact test according to ASTM D256 using a notched strip test piece having a length of 63.5 mm, a width of 12.7 mm, and a thickness of 3.2 mm. The upper limit of the Izod impact strength is not particularly limited, but is, for example, 200 J / m.

[0071] The liquid crystal polymer composition of the present invention has a melt viscosity, measured by the method described below, of preferably 20 to 150 Pa·s, more preferably 30 to 130 Pa·s, and even more preferably 40 to 110 Pa·s. If the melt viscosity is less than 20 Pa·s, problems such as drooling tend to occur during injection molding, while if it exceeds 150 Pa·s, the flowability tends to be insufficient.

[0072] The liquid crystal polymer composition of the present invention has an advantage of excellent heat resistance, with a deflection temperature under load (load 1.82 MPa) measured by the method described below of preferably 180°C or higher, more preferably 190°C or higher, and even more preferably 200°C or higher.

[0073] The liquid crystal polymer composition of the present invention has excellent mechanical properties such as flexural strength and Izod impact strength, as well as excellent thermal conductivity, making it suitable for use as a material for electronic components that are expected to generate heat in high-frequency applications, such as connectors, switches, relays, capacitors, coils, motors, test sockets, transformers, camera modules, and antennas, and is particularly suitable for use in thin-walled molded products. Specifically, the minimum thickness of the molded product is preferably 1.0 mm or less, more preferably 0.8 mm or less, and even more preferably 0.5 mm or less. In the case of thin-walled molded products, the effect of improving the heat dissipation of the molded product can be expected. The minimum thickness of the molded product is usually 0.05 mm or more. [Example]

[0074] The present invention will be described below with reference to examples, but is not limited to these examples in any way. The thermal conductivity, flexural strength, Izod impact strength, melt viscosity, deflection temperature under load (heat resistance), crystalline melting temperature, and compoundability in the examples were measured and evaluated according to the methods described below.

[0075] <Thermal conductivity> The thermal conductivity is calculated from the product of the thermal diffusivity, the specific heat, and the specific gravity, and is the thermal conductivity in the flow direction (MD) when the molten resin composition is filled into a mold. Using an injection molding machine (UH1000-110, manufactured by Nissei Plastic Industrial Co., Ltd.), a cylinder temperature of 20°C above the crystal melting temperature and a mold temperature of 70°C were used to prepare bar flow test pieces (side gate, gate opening 125mm x 0.5mm) measuring 12.7mm x 127mm x 3.2mm thick. These were then cut from the gate side along a line perpendicular to the long axis (the flow direction (MD) when the molten resin composition is filled into the mold), to obtain strip test pieces measuring 12.7mm x 3.2mm x 3.0mm.

[0076] Three of these strip-shaped test pieces were laminated with an adhesive to obtain a 12.7 mm × 9.6 mm × 3.0 mm test piece. The 12.7 mm side was then cut to 10.0 mm to obtain a 10.0 mm × 9.6 mm × 3.0 mm thick plate. The flow direction (MD) of this plate when the molten resin composition was filled into the mold was parallel to the thickness direction. The 9.6 mm × 10 mm surface of this plate was coated with a laser light absorbing spray (Fine Chemical Japan Co., Ltd., Black Guard Spray FC-153). This was used as a sample for thermal conductivity evaluation. The thermal diffusivity in the flow direction (MD) when the molten resin composition was filled into the mold was measured by the laser flash method (Netzsch, Xe Flash Analyzer LFA467 HyperFlash). The specific heat was measured using a differential scanning calorimeter (Exstar6000 manufactured by Seiko Instruments Inc.), and the specific gravity was measured using an electronic hydrometer (SD-200L manufactured by Mirage Trading Co., Ltd.).

[0077] <Bending strength> Using an injection molding machine (UH1000-110, manufactured by Nissei Plastic Industrial Co., Ltd.), injection molding was performed at a cylinder temperature of 20°C above the crystal melting temperature and a mold temperature of 70°C to prepare rectangular bending test specimens (length 127 mm × width 12.7 mm × thickness 3.2 mm). A three-point bending test was performed using an INSTRON 5567 (universal testing machine manufactured by Instron Japan Co., Ltd.) at a test speed of 1.3 mm / min and a span distance of 50 mm in accordance with ASTM D790.

[0078] <Izod impact strength> Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), strip-shaped test specimens measuring 127.0 mm in length, 12.7 mm in width, and 3.2 mm in thickness were molded at a cylinder temperature of 20°C above the crystal melting temperature and a mold temperature of 70°C. The center of each test specimen was cut perpendicular to the lengthwise direction to obtain strip-shaped test specimens measuring 63.5 mm in length, 12.7 mm in width, and 3.2 mm in thickness. After notching, the specimens were measured in accordance with ASTM D256.

[0079] <Melt viscosity> Using a melt viscosity measuring device (Capillograph 1D manufactured by Toyo Seiki Co., Ltd.) and a 1.0 mm diameter × 10 mm capillary, the liquid crystal polymer composition with a crystalline melting temperature of less than 300°C was measured at a measurement temperature of 320°C, and the liquid crystal polymer composition with a crystalline melting temperature of 300°C or more was measured at a measurement temperature of 350°C, at a shear rate of 1000 sec -1 The values ​​at were measured.

[0080] <Deflection temperature under load (DTUL)> Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), rectangular test specimens (length 127 mm x width 12.7 mm x thickness 3.2 mm) were prepared by injection molding at a cylinder temperature of 20°C above the crystal melting temperature and a mold temperature of 70°C. These specimens were used to measure the temperature at which a specified deflection (0.254 mm) was achieved at a load of 1.82 MPa and a heating rate of 2°C / min in accordance with ASTM D648.

[0081] <Compounding> Using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd., TEX30α, Φ32 mm), the resin was melt-mixed at a cylinder temperature of 350°C, a rotation speed of 350 rpm, and a discharge rate of 40 kg / h, and the strands were extruded and pelletized to obtain liquid crystalline resin pellets. The resulting resin pellets were evaluated for compoundability (process stability) based on the following evaluation criteria. If the melt-mixing is unstable, the strands are likely to break, causing problems in the pelletizing process and resulting in a decreased pellet yield. Good: Melt kneading was stable, and the yield of liquid crystal polymer composition pellets was 80% or more. △: Melt kneading was unstable, and the yield of liquid crystal polymer composition pellets was 40% or more but less than 80%. ×: Melt kneading was not stable, and the yield of liquid crystal polymer composition pellets was less than 40%.

[0082] <Crystal Melting Temperature> Using a Seiko Instruments Inc. Exstar 6000 differential scanning calorimeter, the endothermic peak temperature (Tm1) observed when the sample was measured at a temperature increase of 20°C / min from room temperature was measured, and then the sample was held at a temperature 20 to 50°C higher than Tm1 for 10 minutes. The sample was then cooled to room temperature at a temperature decrease of 20°C / min, and again measured at a temperature increase of 20°C / min, and the endothermic peak was observed. The temperature at the peak top was taken as the crystalline melting temperature (Tm).

[0083] In the following examples and comparative examples, the following abbreviations represent the following compounds. [Monomers used in the synthesis of liquid crystal polymers] POB: parahydroxybenzoic acid BON6: 6-hydroxy-2-naphthoic acid HQ: Hydroquinone BP: 4,4'-dihydroxybiphenyl TPA: Terephthalic acid

[0084] [Synthesis example (LCP1)] POB and BON6 were charged in a reaction vessel equipped with a stirrer with a torque meter and a distillation tube in a total amount of 6.5 moles in the composition ratio shown in Table 1, and acetic anhydride was further charged in an amount of 1.01 times the moles of the hydroxyl groups (moles) of all monomers, and deacetic acid polymerization was carried out under the following conditions.

[0085] [Table 1]

[0086] The temperature was raised from room temperature to 145°C in a nitrogen gas atmosphere over 1 hour and maintained at the same temperature for 30 minutes. Next, the temperature was raised to 330°C over 7 hours while distilling off the by-product acetic acid, and then the temperature was raised to 330°C over 80 minutes. The pressure was reduced to 10 mmHg. When the specified torque was reached, the polymerization reaction was terminated. The contents were taken out of the vessel and crushed in a crusher to obtain pellets of the liquid crystal polyester resin. The amount of acetic acid distilled at this time was almost the theoretical value. The crystalline melting temperature (Tm) of the obtained pellets was 278°C.

[0087] [Synthesis example (LCP2)] A reaction vessel equipped with a stirrer with a torque meter and a distillation tube was charged with POB, BON6, HQ, BP, and TPA in the composition ratio shown in Table 2 so that the total amount was 6.5 moles. Furthermore, acetic anhydride was charged in an amount of 1.03 times the moles of the hydroxyl groups (moles) of all the monomers, and deacetic acid polymerization was carried out under the following conditions.

[0088] [Table 2]

[0089] The temperature was raised from room temperature to 150°C in 1 hour under a nitrogen gas atmosphere and maintained at that temperature for 30 minutes. Next, the temperature was raised to 350°C over 7 hours while distilling off the by-product acetic acid, and then the pressure was reduced to 5 mmHg over 80 minutes. The polymerization reaction was terminated when a predetermined torque was reached, and the contents of the reactor were removed and crushed into pellets of liquid crystal polyester resin. The amount of acetic acid distilled during polymerization was nearly the theoretical value. The Tm of the resulting pellets was 339°C.

[0090] The plate-like fillers, glass fibers, PBZ fibers and other fillers used in the following examples and comparative examples are shown below. Plate-shaped filler (boehmite): Kawai Lime Industry Co., Ltd., plate-shaped boehmite "BMT-33" (average particle size: 3 μm, aspect ratio: 5) Plate-shaped filler (talc): Talc "RL119" manufactured by Fuji Talc Kogyo Co., Ltd. (average particle size: 17 μm, aspect ratio: 8) Plate-shaped filler (boron nitride): Boron nitride "GP" manufactured by Denka Co., Ltd. (average particle size 8 μm, aspect ratio: 50)

[0091] PBZ fiber 1: Polybenzoxazole (PBO) fiber "ZYLON HM1mm" (average fiber length: 1mm, average fiber diameter: 12μm), manufactured by Toyobo MC Co., Ltd. PBZ fiber 2: Polybenzoxazole (PBO) fiber "ZYLON HM3mm" (average fiber length: 3mm, average fiber diameter: 12μm), manufactured by Toyobo MC Co., Ltd. Glass fiber: Nippon Electric Glass Co., Ltd., "747H" (average fiber length: 3 mm, average fiber diameter: 10.5 μm) Alumina: Granular alumina "Dipyroxide #7330" manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd. (average particle size: 8 μm, aspect ratio: 1) Titanium oxide: Granular titanium oxide "R-39" manufactured by Sakai Chemical Industry Co., Ltd. (average particle size: 0.23 μm, aspect ratio: 1)

[0092] Examples 1 to 5 and Comparative Examples 1 to 9 The synthesized LCP, the plate-like filler, glass fiber, PBZ fiber, and other fillers were blended to the contents (parts by mass) shown in Table 3, and melt-kneaded at 350°C using a twin-screw extruder (TEX-30, manufactured by Nippon Steel Corporation) to obtain pellets of a liquid crystal polymer composition. Using the methods described above, the thermal conductivity, flexural strength, Izod impact strength, melt viscosity, deflection temperature under load (heat resistance), and compounding properties were measured and evaluated. The results are shown in Table 3. In Comparative Example 3, the raw materials were not meshed well with the screw, preventing continuous melt-kneading and resulting in no pellets, so measurements and evaluations of properties other than compounding properties were not possible.

[0093] As shown in Table 3, all of the liquid crystal polymer compositions of Examples 1 to 5 maintained mechanical strength, toughness, fluidity and heat resistance, and were excellent in compoundability and thermal conductivity.

[0094] In contrast, the liquid crystal polymer compositions of Comparative Examples 1 to 9 were inferior in any one of thermal conductivity, mechanical strength, toughness, heat resistance, and compoundability. [Table 3]

Claims

1. A liquid crystal polymer composition comprising a liquid crystal polymer, a plate-like filler having an aspect ratio of 3 or more, glass fibers having an average fiber diameter of 5 to 15 μm, and polybenzazole fibers having an average fiber diameter of 5 to 15 μm.

2. 2. The liquid crystal polymer composition according to claim 1, comprising 20 to 150 parts by mass of a plate-like filler, 10 to 80 parts by mass of glass fiber, and 3 to 25 parts by mass of polybenzazole fiber, per 100 parts by mass of the liquid crystal polymer.

3. The liquid crystal polymer may be represented by formula (I) and / or formula (II): 【Chemistry 1】 2. The liquid crystal polymer composition according to claim 1, which is a liquid crystal polyester resin containing a repeating unit represented by the formula:

4. The liquid crystal polymer is represented by formula (I) and formula (II): 【Chemistry 2】 4. The liquid crystal polymer composition according to claim 3, which is a liquid crystal polyester resin containing 90 mol % or more of repeating units represented by the following formula in total.

5. The liquid crystal polymer is represented by formula (I) to formula (IV): 【Transformation 3】 2. The liquid crystal polymer composition according to claim 1, which is a liquid crystal polyester resin containing a repeating unit represented by the formula:

6. The repeating units represented by formulas (III) to (IV) are Ar １ and Ar ２ are each independently represented by the formulas (1) to (4) 【Chemistry 4】 6. The liquid crystal polymer composition according to claim 5, wherein each repeating unit is one or more types selected from aromatic groups represented by the following formula:

7. 2. The liquid crystal polymer composition according to claim 1, wherein the plate-like filler is at least one selected from the group consisting of talc, mica, alumina, boehmite, and boron nitride.

8. 2. The liquid crystal polymer composition according to claim 1, wherein the average particle size of the plate-like filler is 0.1 to 50 μm.

9. 2. The liquid crystal polymer composition according to claim 1, wherein the thermal conductivity in the flow direction of the molten resin composition during molding is 2.0 W / m·K or more.

10. 2. The liquid crystal polymer composition according to claim 1, which has a flexural strength of 140 MPa or more as measured in accordance with ASTM D790.

11. 2. The liquid crystal polymer composition according to claim 1, which has an Izod impact strength of 40 J / m or more as measured in accordance with ASTM D256.

12. A molded article made from the liquid crystal polymer composition according to any one of claims 1 to 11.

13. The molded article according to claim 12, wherein the minimum thickness of the molded article is 1.0 mm or less.

14. The molded article according to claim 12, wherein the molded article is a part constituting one selected from the group consisting of a connector, a switch, a relay, a capacitor, a coil, a motor, a test socket, a transformer, a camera module, and an antenna.

Images