Liquid crystal polymer composition

Abstract

To provide a liquid crystal polymer composition that exhibits superior dimensional stability and antistatic performance while maintaining characteristics of a liquid crystal polymer such as mechanical strength and fluidity, and an electric and electronic component produced using the composition.SOLUTION: A liquid crystal polymer composition contains 100 pts.mass of a liquid crystal polymer, 12-45 pts.mass of a graphite having an average particle diameter of 20-100 μm, and 5-35 pts.mass of a glass fiber having an average fiber diameter of 5-15 μm, the composition having a volume resistivity of 1×105 to 1×1012 Ω cm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal polymer composition which provides molded articles with excellent dimensional stability and antistatic properties without impairing mechanical properties. [Background technology]

[0002] Liquid crystal polymers are used in parts in a wide variety of fields due to their excellent mechanical properties, moldability, chemical resistance, gas barrier properties, moisture resistance, electrical properties, etc. In particular, their excellent heat resistance and thin-wall moldability have led to their widespread use in electronic parts for precision instruments and other devices.

[0003] The adhesion of dust and dirt to electronic components can hinder their normal operation, and static electricity is thought to be one of the causes of dust and dirt adhesion. Therefore, electronic components with anti-static properties are in demand, and similar performance is also required for liquid crystal polymers.

[0004] Patent Document 1 attempts to improve the conductivity by blending conductive carbon black into a liquid crystal polymer. However, although the improved conductivity provides an antistatic effect, it cannot be used as an insulating material, and its applications are limited.

[0005] Patent Document 2 describes a semiconductive resin composition in which graphite, a fibrous conductive filler, and a fibrous nonconductive filler are blended with a liquid crystalline polymer. However, depending on the fiber length of the fibrous filler, the fibers may protrude to the surface, resulting in problems with the surface smoothness of the molded product. Another problem is that the inclusion of graphite reduces mechanical properties such as weld strength.

[0006] Patent Document 3 proposes a liquid crystalline resin composition in which a liquid crystalline resin is blended with a fibrous filler having a maximum fiber length of 1000 μm or less and a weight average fiber length of 200 μm or more and 450 μm or less. However, although the use of a fibrous filler satisfying these conditions improves the surface smoothness of molded articles, the antistatic effect is insufficient depending on the type of fibrous filler.

[0007] Therefore, there is a need for a liquid crystalline polymer composition that has excellent dimensional stability and antistatic properties without impairing mechanical properties. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 62-131067 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-194229 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-215530 Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to provide a liquid crystal polymer composition that has excellent dimensional stability and antistatic properties while maintaining the properties of liquid crystal polymers such as mechanical strength and fluidity, and to provide electrical and electronic parts that use said composition. [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 specific graphite and glass fiber in specific proportions with a liquid crystal polymer, the dimensional stability and antistatic properties of the liquid crystal polymer can be improved while maintaining the mechanical strength and fluidity 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 composite material containing 100 parts by mass of liquid crystal polymer, 12 to 45 parts by mass of graphite having an average particle diameter of 20 to 100 μm, and 5 to 35 parts by mass of glass fiber having an average fiber diameter of 5 to 15 μm, and having a volume resistivity of 1 × 10 5 ~1×10 12 Ω·cm, liquid crystal polymer composition. [2] The liquid crystal polymer is represented by formula (I) and formula (II) [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: [3] The liquid crystal polymer is represented by the formula (I) to the formula (IV) [ka] [In the formula, Ar1 and Ar2 each represent a divalent aromatic group.] The liquid crystal polymer composition according to [1], which is a wholly aromatic liquid crystal polyester resin containing a repeating unit represented by the following formula: [4] 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 [3], wherein each of the repeating units is one or more types selected from aromatic groups represented by the following formula: [5] The liquid crystal polymer composition according to [4], wherein the repeating unit represented by formula (III) is a repeating unit in which Ar1 is an aromatic group represented by formula (1), and the repeating unit represented by formula (IV) is a repeating unit in which Ar2 is an aromatic group represented by formula (1) and / or an aromatic group represented by formula (3). [6] The liquid crystal polymer composition according to any one of [1] to [5], wherein the fixed carbon content of the graphite is 90% or more. [7] The liquid crystal polymer composition according to any one of [1] to [6], further comprising 0.1 to 10 parts by mass of carbon black. [8] The liquid crystal polymer composition according to [7], wherein the carbon black has an average particle size of 30 to 200 nm. [9] The liquid crystal polymer composition according to any one of [1] to [8], which has a flexural strength of 140 MPa or more as measured in accordance with ASTM D790.

[10] The liquid crystal polymer composition according to any one of [1] to [9], wherein a flat test piece (thickness: 0.5 mm, length and width: 17 mm, central slit width: 5 mm, thickness: 0.25 mm) having a slit-shaped step in the center, injection molded at a cylinder temperature of 20°C above the crystalline melting temperature and a mold temperature of 70°C, has a warpage of 300 μm or less.

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

[10] .

[12] The molded article according to

[11] , which is a part constituting one type selected from the group consisting of a connector, a switch, a relay, a capacitor, a coil, a transformer, an antenna, an IC tray, a bearing, a shutter plate, and a camera module. [Effects of the Invention]

[0012] The liquid crystal polymer composition of the present invention has the effect of having a low volume resistivity while maintaining the properties of liquid crystal polymers such as mechanical strength and dimensional stability (low warpage), and has excellent antistatic properties, so it is suitable for use in, for example, IC trays, bearings, and shutter plates. 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 of 260 to 360°C, more preferably 290 to 355°C, and even more preferably 310 to 350°C, as measured by a differential scanning calorimeter.

[0016] 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.

[0017] 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.

[0018] 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 the heat resistance, mechanical strength, and ease of adjusting the crystalline melting temperature of the resulting liquid crystal polymer.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] As the liquid crystal polymer used in the present invention, a liquid crystal polyester resin containing repeating units represented by formula (I) and formula (II) is preferably used because of its excellent fluidity and mechanical properties.

[0030] [ka]

[0031] Furthermore, as the liquid crystal polymer used in the present invention, a wholly aromatic liquid crystal polyester resin containing repeating units represented by formulas (I) to (IV) is preferably used because of its excellent fluidity and mechanical properties.

[0032] [ka] [In the formula, Ar1 and Ar2 each represent a divalent aromatic group.]

[0033] 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.

[0034] 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 the aromatic group represented by formula (1), and that the repeating unit represented by formula (IV) is a repeating unit in which Ar2 is the aromatic group represented by formula (1) and / or formula (3).

[0035] [ka]

[0036] 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.

[0037] 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 9), 10), and 14) are more preferred, and liquid crystal polymers consisting of structural units derived from polymerizable monomer 9) are even more preferred.

[0038] The above liquid crystal polymers may be used alone or as a mixture of two or more liquid crystal polymers.

[0039] One preferred embodiment of the liquid crystal polymer used in the present invention is a wholly aromatic liquid crystal polyester resin containing repeating units represented by the following formulas (A) to (D).

[0040] [ka] [In the formula, p, q, r, and s represent the composition ratio (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions: 0.1≦q / (p+q)≦0.9, 8≦q≦34, 10≦r≦25, and 10≦s≦25.]

[0041] The method for producing the liquid crystal polymer used in the present invention will be described below.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] Specific examples of the catalyst include organotin compounds (dialkyltin oxides such as dibutyltin oxide, diaryltin oxides, etc.), titanium dioxide, antimony trioxide, organotitanium compounds (alkoxytitanium silicates, titanium alkoxides, etc.), alkali and alkaline earth metal salts of carboxylic acids (potassium acetate, sodium acetate, etc.), Lewis acids (BF3, etc.), gaseous acid catalysts such as hydrogen halides (HCl, etc.), and the like.

[0050] 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.

[0051] 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.

[0052] The liquid crystal polyester in the form of pellets, flakes, or powder 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.

[0053] The liquid crystal polymer composition of the present invention contains graphite and glass fibers in addition to the liquid crystal polymer.

[0054] The graphite used in the liquid crystal polymer composition of the present invention may be natural graphite, artificial graphite, or a combination of two or more of them. The graphite preferably has a high fixed carbon content, a low ash content such as silicon oxide, and high crystallinity. The fixed carbon content of the graphite is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0055] The average particle size of the graphite is 20 to 100 μm, preferably 25 to 70 μm, and more preferably 30 to 60 μm. If the average particle size is less than 20 μm, compoundability deteriorates, while if it exceeds 100 μm, compoundability deteriorates and fluidity tends to become insufficient. The average particle size of the graphite is the cumulative 50% diameter on a volume basis of the particles, which can be determined by laser diffraction scattering.

[0056] The graphite content is 12 to 45 parts by mass, preferably 13 to 40 parts by mass, and more preferably 15 to 35 parts by mass, per 100 parts by mass of the liquid crystal polymer. If the graphite content is less than 12 parts by mass, the volume resistivity is high and it is difficult to achieve an improvement in warpage. If the graphite content exceeds 45 parts by mass, compounding properties tend to deteriorate and flowability tends to be insufficient.

[0057] The glass fibers used as a raw material for the liquid crystal polymer composition of the present invention have an average fiber diameter of 5 to 15 μm, preferably 8 to 13 μm, and more preferably 10 to 12 μm. The average fiber diameter of the glass fibers in the resulting liquid crystal polymer composition does not substantially change even after melt-kneading.

[0058] The glass fibers used as a raw material for the liquid crystal polymer composition of the present invention preferably have a cut fiber length of 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 μm 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 and adjusted depending on the cut fiber length of the glass fibers used.

[0059] The average fiber diameter and number average fiber length of the glass fibers in the liquid crystal polymer composition are measured by the method described below. <Method for measuring average fiber diameter and number average fiber length 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 average fiber diameter and number-average fiber length are determined from the measurements of 100 fibers.

[0060] The content of the glass fiber in the liquid crystal polymer composition of the present invention is 5 to 35 parts by mass, preferably 8 to 30 parts by mass, and more preferably 10 to 20 parts by mass, based on 100 parts by mass of the liquid crystal polymer.

[0061] By containing the specific graphite and glass fiber in the liquid crystal polymer composition of the present invention in specific proportions as described above, a liquid crystal polymer composition having excellent dimensional stability and antistatic properties while maintaining mechanical properties can be obtained.

[0062] The liquid crystal polymer composition of the present invention may contain other plate-like, fibrous or granular inorganic or organic fillers within the range that does not impair the effects of the present invention.

[0063] Other plate-like fillers that can be used in the present invention include, for example, talc, mica, kaolin, clay, vermiculite, feldspar powder, acid clay, rosewood clay, sericite, sillimanite, bentonite, glass flakes, slate powder, silicate such as silane, carbonate such as calcium carbonate, chalk, barium carbonate, magnesium carbonate, dolomite, barite powder, precipitated calcium sulfate, gypsum, sulfate such as barium sulfate, hydroxide such as hydrated alumina, alumina, antimony oxide, magnesia, plate-like titanium oxide, zinc white, silica, silica sand, quartz, white carbon, oxide such as diatomaceous earth, sulfide such as molybdenum disulfide, plate-like wollastonite, etc., and these can be used alone or in combination of two or more.Among these, from the viewpoint of improving the mechanical properties and heat resistance of liquid crystal polymer composition, talc, mica and kaolin are preferred.

[0064] Other fibrous fillers that can be used in the present invention include, for example, milled glass, silica alumina fiber, alumina fiber, carbon fiber, aramid fiber, polyarylate fiber, polybenzimidazole fiber, potassium titanate whisker, aluminum borate whisker, acicular titanium oxide, calcium silicates such as wollastonite, xonotlite, calcium titanate, aluminum borate, acicular calcium carbonate, acicular titanium oxide, and tetrapod-type zinc oxide, and these can be used alone or in combination of two or more.

[0065] Other granular fillers that can be used in the present invention include, for example, calcium carbonate and glass beads, and these can be used alone or in combination of two or more kinds.

[0066] When the liquid crystal polymer composition of the present invention contains other inorganic or organic fillers, the content thereof is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, per 100 parts by mass of the liquid crystal polymer. If the content of these other fillers exceeds the upper limit, the fluidity and thermal stability tend to decrease.

[0067] The liquid crystal polymer composition of the present invention may contain other additives within the range that does not impair the effects of the present invention.

[0068] Other additives include, for example, lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid metal salts (here, higher fatty acids refer to, for example, those having 10 to 25 carbon atoms), and fluorocarbon surfactants; release improvers such as polysiloxanes and fluororesins; colorants such as dyes and pigments; flame retardants, antistatic agents, surfactants; antioxidants such as phosphorus-based antioxidants, phenolic antioxidants, and sulfur-based antioxidants; weathering agents, heat stabilizers, and neutralizing agents. Additives with external lubricant properties, such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon surfactants, may be applied to the surface of pellets of the liquid crystal polymer composition before molding the composition. These additives may be used alone or in combination of two or more.

[0069] The content of these other additives 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, based on 100 parts by mass of the liquid crystal polymer.

[0070] Among these other additives, it is preferable to blend carbon black in the liquid crystal polymer composition of the present invention. The preferred content of carbon black per 100 parts by mass of the liquid crystal polymer is in the above-mentioned range, but when the liquid crystal polymer composition of the present invention contains 10 parts by mass or less of carbon black, it tends to be possible to obtain the function as a colorant and also to obtain the effect of improving antistatic properties.

[0071] When carbon black is blended into the liquid crystal polymer composition of the present invention, the carbon black used preferably has an average particle size of 30 to 200 nm, more preferably 40 to 150 nm, and even more preferably 50 to 100 nm. If the average particle size is less than 30 nm, carbon black aggregates tend to easily occur, and if it exceeds 200 nm, colorability tends to be insufficient.

[0072] When carbon black is blended into the liquid crystal polymer composition of the present invention, the content is more preferably 0.1 to 10 parts by mass, even more preferably 0.3 to 7 parts by mass, and particularly preferably 0.5 to 5 parts by mass, per 100 parts by mass of the liquid crystal polymer composition.

[0073] The liquid crystal polymer composition of the present invention may further contain other resin components within the scope of the present invention, such as thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether and its modified products, polysulfone, polyethersulfone, polyetherimide, and polyamideimide, and thermosetting resins such as phenolic resin, epoxy resin, and polyimide resin.

[0074] The other resin components may be contained alone or in combination of two or more. The content of the other resin components is not particularly limited and may be determined appropriately depending on the use and purpose of the liquid crystal polymer composition. Typically, the total content of the other resins is preferably added in a range of 0.1 to 100 parts by mass, more preferably 0.2 to 80 parts by mass, per 100 parts by mass of the liquid crystal polymer.

[0075] The liquid crystal polymer composition of the present invention can be prepared by blending a liquid crystal polymer, graphite, and glass fiber, and optionally other fillers, other additives such as carbon black, and other resin components in a predetermined composition, and melt-kneading the mixture using a Banbury mixer, a kneader, a single-screw or twin-screw extruder, or the like.

[0076] The liquid crystal polymer composition of the present invention has a volume resistivity of 1×10 measured by the method described below with the above formulation. 5 ~1×10 12 Ω·cm. The volume resistivity is 1×10 6 ~1×10 11 Ω·cm is preferred, and 1×10 7 ~1×10 10 It is more preferable that the volume resistivity is 1×10 Ω·cm. 5If the resistivity is less than 1×10 Ω·cm, it becomes difficult to use it as an insulating material, and the mechanical properties and compounding properties tend to be impaired. 12 If it exceeds Ω·cm, the antistatic effect will be insufficient.

[0077] The liquid crystal polymer composition of the present invention has a bending strength of preferably 140 MPa or more, more preferably 145 MPa or more, and even more preferably 150 MPa or more in a bending test using a 3.2 mm thick ASTM No. 4 bending test piece. The upper limit of the bending strength is not particularly limited, but is, for example, 200 MPa.

[0078] The liquid crystal polymer composition of the present invention has the advantage that the amount of warpage measured by the method described below is preferably less than 300 μm, more preferably less than 200 μm, and even more preferably less than 150 μm, and has excellent dimensional stability.

[0079] The liquid crystal polymer composition of the present invention has a melt viscosity, measured by the method described below, of preferably 10 to 50 Pa·s, more preferably 15 to 45 Pa·s, and even more preferably 20 to 40 Pa·s. If the melt viscosity is less than 10 Pa·s, problems such as drooling tend to occur during injection molding, while if it exceeds 50 Pa·s, the flowability tends to be insufficient.

[0080] The liquid crystal polymer composition of the present invention thus obtained can be molded or processed by a known molding method using an injection molding machine, an extruder, or the like to obtain a desired molded product.

[0081] Molded articles obtained using the liquid crystal polymer composition of the present invention exhibit good weld strength and metal adhesion, and are therefore suitable for use in electronic parts such as connectors, switches, relays, capacitors, coils, transformers, antennas, IC trays, bearings, shutter plates, and camera modules. [Example]

[0082] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, the volume resistivity, bending strength, warpage (dimensional stability), melt viscosity, and compoundability were evaluated by the methods described below.

[0083] <Volume resistivity> 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 flat test specimens (length 100 mm x width 100 mm x thickness 1 mm). The volume resistivity was measured in accordance with JIS K6911 using an ultra-high resistance meter (ADVANTEST R8340A manufactured by ADC Corporation) one minute after applying a voltage of 500V.

[0084] <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.

[0085] <Warpage (dimensional stability)> Using an injection molding machine (NEX15-1E, manufactured by Nissei Plastic Industrial Co., Ltd.) with a clamping pressure of 15 tonnes, the specimens were injection molded at a cylinder temperature of 20°C above the crystal melting point and a mold temperature of 70°C to produce flat test specimens (0.5 mm thick, 17 mm long and 17 mm long, with a central slit width of 5 mm and a thickness of 0.25 mm) with a slit-like step in the center. The amount of warpage of each test specimen was measured using a three-dimensional measuring machine (One Shot 3D VR-3000, manufactured by Keyence Corporation) as [maximum warpage height - test specimen thickness (0.5 mm)].

[0086] <Melt viscosity> The melt viscosity was measured using a melt viscosity measuring device (Capillograph 1D manufactured by Toyo Seiki Co., Ltd.) with a 1.0 mm diameter x 10 mm capillary at a shear rate of 1000 sec -1 The melt viscosity of each sample was measured at the crystal melting temperature (Tm) + 20°C under the above conditions.

[0087] <Compounding> Using a twin-screw extruder (manufactured by The Japan Steel Works, Ltd., TEX30α, Φ32 mm), the mixture was melt-mixed at a cylinder temperature of 360°C, a rotation speed of 350 rpm, and a discharge rate of 35 kg / h, followed by pelletization to obtain liquid crystal polymer composition pellets. The resulting resin pellets were evaluated for compoundability based on the following evaluation criteria. Here, the stability of the melt-mixing was determined using the stability of the discharge rate as an index. 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%.

[0088] In the examples and comparative examples, the following abbreviations represent the following compounds. POB: parahydroxybenzoic acid BON6: 6-hydroxy-2-naphthoic acid HQ: Hydroquinone BP: 4,4'-dihydroxybiphenyl TPA: Terephthalic acid

[0089] [Synthesis Example 1 (LCP1)] 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 a total amount of 6.5 moles in the composition ratios shown in Table 1, and acetic anhydride was further charged in an amount of 1.03 moles relative to the amount (moles) of hydroxyl groups in all monomers, and deacetic acid polymerization was carried out under the following conditions.

[0090] [Table 1]

[0091] 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 crystalline melting temperature (Tm) of the resulting pellets was 332°C.

[0092] [Synthesis example 2 (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.

[0093] [Table 2]

[0094] The temperature was raised from room temperature to 150°C in a nitrogen gas atmosphere over 1 hour 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 crystalline melting temperature (Tm) of the resulting pellets was 339°C.

[0095] The fillers and additives used in the following examples and comparative examples are shown below. Graphite 1: Graphite "PC-30" (flake-shaped, average particle size: 35 μm, fixed carbon content: 99.46%), manufactured by Ito Graphite Co., Ltd. Graphite 2: Fuji Graphite Industries Co., Ltd., graphite "AED-200" (flake-shaped, average particle size: 200 μm, fixed carbon content: 99.6%) Glass fiber: Nippon Electric Glass Co., Ltd., "747H" (average fiber diameter: 10.5 μm, average fiber length: 3000 μm) Talc: Fuji Talc Industrial Co., Ltd., talc "RL119" (plate-shaped, average particle size: 17 μm) Carbon fiber: Mitsubishi Chemical Corporation, carbon fiber "TR06U B4J" (average fiber diameter: 7 μm, average fiber length: 6000 μm) Carbon black (CB): Mitsubishi Chemical Corporation's carbon black "Mitsubishi Carbon Black #5B" (average primary particle size: 76 nm)

[0096] Examples 1 to 5 and Comparative Examples 1 to 8 The LCPs synthesized in Synthesis Examples 1 and 2, and the above fillers and additives 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 liquid crystal polymer composition. The volume resistivity, flexural strength, warpage (dimensional stability), melt viscosity, and compoundability were measured and evaluated using the methods described above. The results are shown in Table 3. In Example 1, the number average fiber length of the glass fibers in the liquid crystal polymer composition was 345 μm.

[0097] As shown in Table 3, the liquid crystal polymer compositions of Examples 1 to 5 all had a volume resistivity of 1×10 5 ~1×10 12 Ω·cm, excellent antistatic properties, small warpage, and moderate melt viscosity meant that the film also had excellent dimensional stability and flowability.

[0098] In contrast, as shown in Table 3, the liquid crystal polymer compositions of Comparative Examples 1 to 8 were inferior in any one of volume resistivity, bending strength, amount of warpage, melt viscosity, and compoundability, and were not suitable as molding materials.

[0099] [Table 3]

Claims

1. The composition contains 100 parts by mass of a liquid crystal polymer, 12 to 45 parts by mass of graphite having an average particle diameter of 20 to 100 μm, and 5 to 35 parts by mass of glass fiber having an average fiber diameter of 5 to 15 μm, and has a volume resistivity of 1×10 ５ ~1 x 10 １２ Ω·cm.

2. The liquid crystal polymer is represented by formula (I) and 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:

3. The liquid crystal polymer is represented by formula (I) to formula (IV): 【Chemistry 2】 [In the formula, Ar １ and Ar ２ each represents a divalent aromatic group.

2. The liquid crystal polymer composition according to claim 1, which is a wholly aromatic liquid crystal polyester resin containing a repeating unit represented by the formula:

4. 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) 【Transformation 3】 4. The liquid crystal polymer composition according to claim 3, wherein each repeating unit is one or more types selected from aromatic groups represented by the following formula:

5. The repeating unit represented by formula (III) is Ar １ is a repeating unit which is an aromatic group represented by formula (1), and the repeating unit represented by formula (IV) is a repeating unit which is an aromatic group represented by formula (1), ２ The liquid crystal polymer composition according to claim 4, wherein R is a repeating unit which is an aromatic group represented by formula (1) and / or R is a repeating unit which is an aromatic group represented by formula (3).

6. 2. The liquid crystalline polymer composition according to claim 1, wherein the graphite has a fixed carbon content of 90% or more.

7. The liquid crystal polymer composition according to claim 1, further comprising 0.1 to 10 parts by mass of carbon black.

8. 8. The liquid crystal polymer composition according to claim 7, wherein the carbon black has an average particle size of 30 to 200 nm.

9. 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.

10. 2. The liquid crystal polymer composition according to claim 1, wherein a flat test piece (thickness: 0.5 mm, length and width: 17 mm, central slit width: 5 mm, thickness: 0.25 mm) having a slit-like step in the center, which is injection molded at a cylinder temperature of 20°C higher than the crystalline melting temperature and a mold temperature of 70°C, has a warpage of 300 μm or less.

11. A molded article made from the liquid crystal polymer composition according to any one of claims 1 to 10.

12. The molded article according to claim 11, which is a part constituting one selected from the group consisting of a connector, a switch, a relay, a capacitor, a coil, a transformer, an antenna, an IC tray, a bearing, a shutter plate, and a camera module.

Images