Liquid crystal polyester resin composition

Abstract

To provide a liquid crystal polyester resin composition excellent in thin-wall fluidity and blister resistance while maintaining mechanical strength and heat resistance of a liquid crystal polyester.SOLUTION: The present invention relates to compounds of formulae [I] to [V] Wherein p, q, r, s, and t are each a composition ratio (mol%) of each repeating unit in the liquid crystal polyester resin and satisfy the following conditions: 15 ≤ p ≤ 30, 5 ≤ q ≤ 25, 15 ≤ r ≤ 35, 10 ≤ s ≤ 30, 10 ≤ t ≤ 30, 1.05 ≤ r / q ≤ 5.0, and p + q + r + s + t ≥ 95, and 0.1 to 70 parts by mass of a plate-like filler having an aspect ratio of 3 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal polyester resin composition that has excellent thin-wall flowability and blister resistance while maintaining the mechanical strength and heat resistance of liquid crystal polyester. [Background technology]

[0002] Liquid crystal polyesters have excellent moldability and high heat resistance, and these properties are utilized to their advantage in applications such as electronic components such as connectors, relays, bobbins, etc. In recent years, electronic components have become more highly integrated, smaller, thinner, and thinner, with connector components in particular showing a notable trend toward smaller size and thinner wall thickness.

[0003] Typical examples of such thin-walled connectors include board-to-board connectors used to join printed wiring boards together, and FPC connectors used to connect flexible printed circuit boards (FPCs) to printed wiring boards.

[0004] Board-to-board connectors and FPC connectors require heat resistance to withstand reflow soldering, and as electronic devices that use printed wiring boards become smaller, the components themselves must also be made smaller. For example, narrow-pitch connectors with a pitch of 0.3 to 0.4 mm between the metal terminals of the connector are now available. Thin connectors with a stacking height of 0.6 mm when mated are also available.

[0005] However, in order to meet the demand for smaller size and thinner walls, there is a risk of short shots occurring due to insufficient fluidity of the resin during molding of the connector. Therefore, there is a need to further improve the fluidity of the resin in the thin-walled parts of molded products (thin-wall fluidity).

[0006] Furthermore, when molded products are left in a high-temperature atmosphere for a long period of time or when soldering is performed, swellings called blisters may occur on the surface. The cause of this phenomenon is not clear, but it is thought that air entrapped during the molding of the liquid crystal polyester is brought into the molded product, and then when the product is subjected to high-temperature heat treatment, this air expands and pushes up against the surface of the molded product that has softened due to the heat, resulting in the appearance of blisters.

[0007] Liquid crystal polyester, which is used to form thin-walled connectors such as board-to-board connectors and FPC connectors, is required to have excellent thin-wall flowability and blister resistance while maintaining the properties of liquid crystal polyester, such as mechanical strength and heat resistance.

[0008] Patent Document 1 proposes a liquid crystalline polyester composition that contains a specific terphenyl and a liquid crystalline polyester, and thereby can obtain a molded article that has high fluidity and anisotropy relaxation of the liquid crystalline polyester, while sufficiently reducing gas generation to an extent that blister abnormalities, etc. However, the resin composition does not have sufficient fluidity, and there is room for improvement.

[0009] Patent Document 2 proposes a liquid crystal polyester resin composition that contains a liquid crystal polyester, talc, and mica in a predetermined ratio, and that has high fluidity, high thin-wall strength, solder resistance, and can produce molded articles with reduced warpage during reflow treatment. However, this resin composition also does not have sufficient fluidity, and there is room for improvement.

[0010] One way to improve thin-wall flowability is to reduce the viscosity of the resin, but this makes it easier for air to be trapped inside the molded product during molding, resulting in the formation of blisters. As such, various studies have been conducted on liquid crystal polyester resin compositions, but it has been thought to be difficult to achieve both high levels of thin-wall flowability and blister resistance. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-30015 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-109096 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a liquid crystal polyester resin composition that has excellent thin-wall flowability and blister resistance while maintaining the mechanical strength and heat resistance that liquid crystal polyester has. [Means for solving the problem]

[0013] As a result of intensive research in view of the above problems, the present inventors have discovered that by blending a specific amount of a specific plate-like filler with a liquid crystal polyester resin consisting of specific repeating units, a liquid crystal polyester resin composition can be obtained that maintains the mechanical strength and heat resistance of the liquid crystal polyester while exhibiting excellent thin-wall flowability and blister resistance, and have thus completed the present invention.

[0014] That is, the present invention includes the following preferred embodiments. [1] Formula [I]~[V] [ka] [In the formula, p, q, r, s, and t are the composition ratios (mol %) of the respective repeating units in the liquid crystal polyester resin, and satisfy the following conditions: 15≦p≦30, 5≦q≦25, 15≦r≦35, 10≦s≦30, 10≦t≦30, 1.05≦r / q≦5.0, p+q+r+s+t≧95] and 0.1 to 70 parts by mass of a plate-like filler having an aspect ratio of 3 or more. [2] The liquid crystal polyester resin composition according to [1], wherein the platy filler is mica and / or talc. [3] The liquid crystal polyester resin composition according to [1] or [2], further comprising 0.1 to 70 parts by mass of a fibrous filler per 100 parts by mass of the liquid crystal polyester resin. [4] The liquid crystal polyester resin composition according to [3], wherein the fibrous filler is glass fiber. [5] The liquid crystal polyester resin composition according to any one of [1] to [4], which has a deflection temperature under load of 240°C or higher as measured at a load of 0.48 MPa in accordance with ASTM D648. [6] The liquid crystal polyester resin composition according to any one of [1] to [5], wherein the Izod impact strength measured in accordance with ASTM D256 using a notched strip specimen having a length of 63.5 mm, a width of 12.7 mm and a thickness of 3.2 mm is 100 J / m or more. [7] A molded article made from the liquid crystal polyester resin composition according to any one of [1] to [6]. [8] The molded article according to [7], which is a component constituting one selected from the group consisting of a connector, a switch, a relay, a bobbin, a capacitor, a coil, a motor, a fan, a test socket, a transformer, a camera module, and an antenna. [Effects of the Invention]

[0015] The liquid crystal polyester resin composition of the present invention has excellent thin-wall fluidity and blister resistance while maintaining the mechanical strength and heat resistance of liquid crystal polyester, and is therefore suitable for a variety of applications, such as electrical and electronic parts of various communication equipment and electronic devices, for example, connectors, switches, relays, bobbins, capacitors, coils, motors, fans, test sockets, transformers, camera modules, and antennas. DETAILED DESCRIPTION OF THE INVENTION

[0016] The liquid crystal polyester resin used in the present invention is a liquid crystal polyester resin that forms an anisotropic melt phase, which is called a thermotropic liquid crystal polyester resin by those skilled in the art.

[0017] The properties of the anisotropic molten phase of the liquid crystal polyester resin can be confirmed by a conventional polarized light inspection method using cross polarizers, that is, by observing a sample placed on a hot stage under a nitrogen atmosphere.

[0018] The liquid crystal polyester resin used in the present invention is represented by the formulas [I] to [V] [ka] [In the formula, p, q, r, s, and t are the composition ratios (mol %) of the respective repeating units in the liquid crystal polyester resin, and satisfy the following conditions: 15≦p≦30, 5≦q≦25, 15≦r≦35, 10≦s≦30, 10≦t≦30, 1.05≦r / q≦5.0, p+q+r+s+t≧95] It is composed of a repeating unit represented by the following formula:

[0019] The composition ratio p in the formula [I] is 15 to 30 mol %, preferably 16 to 24 mol %, more preferably 18 to 22 mol %, further preferably 19 to 21 mol %, and particularly preferably 19.5 to 20.5 mol %.

[0020] In a liquid crystal polyester resin comprising repeating units represented by formulas [I] to [V], if the repeating units represented by formula [I] are less than 15 mol%, it is difficult to maintain mechanical strength, and if they are more than 30 mol%, the crystalline melting temperature decreases, resulting in poor heat resistance.

[0021] Specific examples of the monomer that gives the repeating unit represented by formula [I] include 4-hydroxybenzoic acid and its ester-forming derivatives such as acylates, ester derivatives and acid halides.

[0022] The composition ratio q in the formula [II] is 5 to 25 mol %, preferably 7 to 20 mol %, more preferably 8 to 15 mol %, further preferably 9 to 12 mol %, and particularly preferably 9.5 to 11 mol %.

[0023] Specific examples of the monomer that gives the repeating unit represented by formula [II] include hydroquinone and its ester-forming derivatives such as acylated products.

[0024] The composition ratio r in the formula [III] is 15 to 35 mol %, preferably 20 to 33 mol %, more preferably 25 to 32 mol %, further preferably 27 to 31 mol %, and particularly preferably 29 to 30.5 mol %.

[0025] Specific examples of the monomer that gives the repeating unit represented by formula [III] include 4,4'-dihydroxybiphenyl and its ester-forming derivatives such as acylated products.

[0026] The composition ratio s of the formula [IV] is 10 to 30 mol %, preferably 15 to 28 mol %, more preferably 18 to 26 mol %, further preferably 19 to 22 mol %, and particularly preferably 19.5 to 20.5 mol %.

[0027] Specific examples of the monomer that provides the repeating unit represented by formula [IV] include terephthalic acid and its ester-forming derivatives such as ester derivatives and acid halides.

[0028] The composition ratio t of the formula [V] is 10 to 30 mol %, preferably 15 to 28 mol %, more preferably 18 to 26 mol %, further preferably 19 to 22 mol %, and particularly preferably 19.5 to 20.5 mol %.

[0029] Specific examples of the monomer that provides the repeating unit represented by formula [V] include 2,6-naphthalenedicarboxylic acid, and ester-forming derivatives thereof such as ester derivatives and acid halides.

[0030] The composition ratio q according to formula [II] and the composition ratio r according to formula [III] satisfy q < r, and r / q is preferably from 1.05 to 5.0, more preferably from 1.5 to 4.5, still more preferably from 2.0 to 4.0, and even more preferably from 2.5 to 3.5.

[0031] The total [p + q + r + s + t] of the composition ratios of the repeating units in the liquid crystal polyester resin used in the present invention is 95 mol% or more. Other repeating units may be further contained within a range not impairing the object of the present invention.

[0032] Examples of the monomer that provides other repeating units include other aromatic hydroxycarboxylic acids, aromatic diols, aromatic dicarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic hydroxydicarboxylic acids, aliphatic diols, aliphatic dicarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

[0033] The total of the composition ratios of the repeating units provided by these other monomer components is preferably 3 mol% or less, more preferably 1 mol% or less, and still more preferably substantially not contained (for example, 0.5% or less) in the whole repeating units. In the most preferred embodiment of the present invention, the total [p + q + r + s + t] of the composition ratios of the repeating units in the liquid crystal polyester resin is 100 mol%.

[0034] Hereinafter, the method for producing the liquid crystal polyester resin used in the present invention will be described.

[0035] There is no particular limitation on the method for producing the liquid crystal polyester resin used in the present invention, and any known polycondensation method for forming an ester bond with the above-mentioned monomer components, such as a melt acidolysis method or a slurry polymerization method, can be used.

[0036] The melt acidolysis method is a suitable method for producing the liquid crystalline polyester resin used in the present invention, in which the monomers are first heated to form a melt of reactants, and the reaction is continued to obtain a molten polyester. A vacuum may be applied to facilitate removal of volatile by-products (e.g., acetic acid, water, etc.) produced in the final stage of condensation.

[0037] Slurry polymerization is a process in which the reaction is carried out in the presence of a heat exchange fluid, and the solid product is obtained in a state suspended in the heat exchange medium.

[0038] In both the melt acidolysis method and the slurry polymerization method, the polymerizable monomer components used in producing the liquid crystal polyester resin can be subjected to the reaction at room temperature in a modified form in which the hydroxyl group is acylated, i.e., as a lower acylated product. The lower acyl group preferably has 2 to 5 carbon atoms, more preferably 2 or 3 carbon atoms. Particularly preferred is a method in which an acetylated product of the monomer component is used in the reaction.

[0039] The lower acylated monomer may be one which has been previously synthesized by separate acylation, or may be produced in the reaction system by adding an acylating agent such as acetic anhydride to the monomer during the production of the liquid crystal polyester resin.

[0040] In either the molten acidolysis method or the slurry polymerization method, a catalyst may be used during the reaction, if necessary.

[0041] 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.

[0042] The amount of the catalyst used is preferably 10 to 1000 ppm, more preferably 20 to 200 ppm, based on the mass of the monomer.

[0043] The liquid crystal polyester resin obtained by such a polycondensation reaction is extracted in a molten state from a polymerization reaction vessel, and then processed into pellets, flakes, or powder, and is subjected to molding or melt-kneading.

[0044] The liquid crystal polyester resin in the form of pellets, flakes, or powder may be heat-treated in a substantially solid state under reduced pressure, in vacuum, or in an atmosphere of an inert gas such as nitrogen or helium, in order to increase the molecular weight and improve the heat resistance.

[0045] The temperature of the heat treatment is not particularly limited as long as the liquid crystal polyester resin does not melt, but is preferably 260 to 350°C, more preferably 280 to 320°C.

[0046] The melt viscosity of the liquid crystal polyester resin of the present invention (measured with a capillary rheometer, 350°C, 1000 s -1 ) is preferably 1 to 200 Pa·s, more preferably 3 to 100 Pa·s, even more preferably 4 to 80 Pa·s, and particularly preferably 5 to 40 Pa·s.

[0047] If the melt viscosity is less than 1 Pa·s, drooling and stringiness tend to occur during injection molding, and if it exceeds 200 Pa·s, fluidity tends to decrease.

[0048] The plate-like filler used in the present invention refers to a filler in the form of a disk, rectangular plate, strip, or irregular plate, which has a three-dimensional shape that extends in two directions but not in the remaining direction. Specific examples include silicates such as talc, mica, graphite, dolomite, clay, glass flake, 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 flake-like fillers, talc and / or mica are preferred, and mica is particularly preferred, in that they provide the liquid crystal polyester resin composition with excellent thin-wall fluidity and blister resistance.

[0049] The average particle size of the plate-like filler is preferably 0.1 to 100 μm, more preferably 0.5 to 80 μm, and even more preferably 3 to 50 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.

[0050] The plate-like filler contained in the liquid crystal polyester resin 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 500, more preferably 5 to 300, still more preferably 10 to 250, and particularly preferably 30 to 200. The aspect ratio refers to the average particle diameter divided by the thickness.

[0051] 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

[0052] The plate-like filler may be treated with a known surface treatment agent before use.

[0053] In the liquid crystal polyester resin composition of the present invention, the content of the plate-like filler is 0.1 to 70 parts by mass, preferably 1 to 60 parts by mass, more preferably 5 to 55 parts by mass, and even more preferably 15 to 50 parts by mass, relative to 100 parts by mass of the liquid crystal polyester resin. If the content of the plate-like filler is less than 0.1 part by mass, blister resistance tends to be insufficient, and if it exceeds 70 parts by mass, flowability tends to be reduced.

[0054] Specific examples of fibrous fillers optionally used in the present invention include one or more selected from the group consisting of glass fibers, silica alumina fibers, alumina fibers, carbon fibers, aramid fibers, polyarylate fibers, polybenzimidazole fibers, potassium titanate whiskers, aluminum borate whiskers, acicular titanium oxide, calcium silicates such as wollastonite, xonotlite, calcium titanate, aluminum borate, acicular calcium carbonate, and basalt fibers. Among these fibrous fillers, glass fibers and / or carbon fibers are preferred, with glass fibers being particularly preferred, as they provide excellent mechanical strength to the liquid crystal polyester resin composition.

[0055] The average fiber diameter and average fiber length of the fibrous filler optionally used in the present invention are preferably 0.1 to 50 μm in average fiber diameter and 20 μm to 10 mm in average fiber length.

[0056] The above-mentioned fibrous filler may be treated with a known surface treatment agent before use.

[0057] In the liquid crystal polyester resin composition of the present invention, the content of a fibrous filler, when used, is 0.1 to 70 parts by mass, preferably 1 to 60 parts by mass, more preferably 3 to 50 parts by mass, even more preferably 5 to 40 parts by mass, and particularly preferably 8 to 30 parts by mass, relative to 100 parts by mass of the liquid crystal polyester resin. If the content of the plate-like filler is less than 0.1 part by mass, the strength improvement effect of using the fibrous filler tends not to be obtained, and if it exceeds 70 parts by mass, the fluidity tends to decrease.

[0058] When the fibrous filler optionally used in the present invention is glass fiber, examples of the glass fiber include those produced by various methods, such as chopped glass fiber of long fiber type and milled glass fiber of short fiber type, etc. Two or more of these may be used in combination.

[0059] The types of glass fibers that may be optionally used in the present invention include E-glass, A-glass, C-glass, D-glass, AR-glass, R-glass, S-glass, etc., and mixtures thereof. Among these, E-glass is preferred because it has excellent strength and is easily available.

[0060] The glass fibers optionally used in the present invention may be treated with a coupling agent such as a silane-based coupling agent or a titanium-based coupling agent, if necessary.

[0061] The glass fibers optionally used in the present invention may be coated with a thermoplastic resin such as a urethane resin, an acrylic resin, or an ethylene / vinyl acetate copolymer, or a thermosetting resin such as an epoxy resin, or may be treated with a sizing agent.

[0062] The average fiber diameter of the glass fibers optionally used in the present invention is preferably 3 to 20 μm, more preferably 5 to 16 μm, and even more preferably 7 to 13 μm. The average fiber diameter of the glass fibers in the resulting liquid crystal polyester resin composition does not substantially change even after melt-kneading.

[0063] The cut fiber length of the raw glass fibers optionally used in the present invention 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 polyester resin composition is preferably 10 to 600 μm, more preferably 30 to 500 μm, and even more preferably 50 to 450 μm. The glass fibers are usually broken or crushed during blending with the liquid crystal polyester resin, etc., resulting in the number average fiber length in the liquid crystal polyester resin composition. To obtain a liquid crystal polyester resin 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.

[0064] The average fiber diameter and number-average fiber length of glass fibers can be measured by observation under a microscope. First, 1.0 g of a liquid crystal polyester resin composition is placed in a crucible and incinerated in an electric furnace at 500°C for 5 hours. The residue is dispersed in methanol and spread on a glass slide to prepare a sample. Next, in the projected image of the glass fibers in the microscope field, the length in the longitudinal direction is read as the fiber length, and the length in the direction perpendicular to the longitudinal direction is read as the fiber diameter, and the arithmetic mean is calculated. The modulus of the average value is 200 or more.

[0065] Furthermore, the liquid crystal polyester resin composition of the present invention may contain, for example, a granular inorganic filler or organic filler in addition to the above-mentioned plate-like filler and fibrous filler, as long as the object of the present invention is not impaired.

[0066] Other granular fillers that can be used in the present invention include, for example, silica, alumina, titanium oxide, calcium carbonate, glass beads, glass balloons, barium sulfate, boron nitride, silicon carbide, and resin beads, and these can be used alone or in combination of two or more.

[0067] The content of these other granular fillers is preferably 50 parts by mass or less, more preferably 0.1 to 30 parts by mass, relative to 100 parts by mass of the liquid crystal polyester resin. If the content of these other granular fillers exceeds 50 parts by mass, thin-wall flowability tends to deteriorate.

[0068] The liquid crystal polyester resin composition of the present invention may contain other additives within the range that does not impair the effects of the present invention.

[0069] Other additives used in the present invention 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), release improvers such as polysiloxanes and fluororesins, colorants such as dyes, pigments, and carbon black, flame retardants, antistatic agents, surfactants, antioxidants such as phosphorus-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants, weather resistance agents, heat stabilizers, and neutralizing agents. These additives may be used alone or in combination of two or more.

[0070] The content of these other additives is preferably 10 parts by mass or less, more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the liquid crystal polyester resin. If the content of these other additives exceeds 10 parts by mass, the thermal stability tends to deteriorate.

[0071] When molding the wholly aromatic liquid crystal polyester resin composition, substances having an external lubricant effect, such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon surfactants, may be attached to the surface of the pellets of the liquid crystal polyester resin composition in advance.

[0072] The liquid crystal polyester resin 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 modified products thereof, polysulfone, polyethersulfone, polyetherimide, polyamideimide, and the like, and thermosetting resins such as phenolic resin, epoxy resin, polyimide resin, and the like.

[0073] 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 appropriately determined depending on the use and purpose of the liquid crystal polyester resin composition. Typically, the total content of the other resins is preferably added in a range of 0.1 to 100 parts by mass, particularly 0.1 to 80 parts by mass, per 100 parts by mass of the liquid crystal polyester resin.

[0074] A liquid crystal polyester resin composition can be prepared by blending a liquid crystal polyester resin and a plate-like filler, an optional fibrous filler, and optionally other granular fillers, other additives, other resin components, etc. in a predetermined composition and melt-kneading the mixture using a Banbury mixer, a kneader, a single-screw or twin-screw extruder, etc.

[0075] The liquid crystal polyester resin composition of the present invention thus obtained is molded or processed by a known molding method using an injection molding machine, an extruder, or the like.

[0076] The liquid crystal polyester resin composition of the present invention preferably has a tensile strength of 100 MPa or more, more preferably 105 MPa or more, and even more preferably 110 MPa or more, in a tensile test in accordance with ASTM D638 using an ASTM No. 4 dumbbell test piece having a thickness of 3.2 mm. If the tensile strength is less than 100 MPa, the composition tends to be easily broken when used as a part. The upper limit of the tensile strength is not particularly limited, but is, for example, 250 MPa.

[0077] The liquid crystal polyester resin composition of the present invention preferably has a tensile elongation at break of 2.0% or more, more preferably 2.5% or more, and even more preferably 3.0% or more, in a tensile test in accordance with ASTM D638 using an ASTM No. 4 dumbbell test piece having a thickness of 3.2 mm. If the tensile elongation at break is less than 2.0%, the composition tends to be easily broken when used as a part. The upper limit of the tensile elongation at break is not particularly limited, but is, for example, 10%.

[0078] In an Izod impact test according to ASTM D256 using a notched strip specimen measuring 63.5 mm in length, 12.7 mm in width, and 3.2 mm in thickness, the liquid crystal polyester resin composition of the present invention preferably has an Izod impact strength of 100 J / m or more, more preferably 105 J / m or more, and even more preferably 110 J / m or more. If the Izod impact strength is less than 100 J / m, the composition tends to be easily broken when used as a part. The upper limit of the Izod impact strength is not particularly limited, but is, for example, 300 J / m.

[0079] The liquid crystal polyester resin composition of the present invention preferably has a deflection temperature under load (low load DTUL, load 0.48 MPa) of 240°C or higher, more preferably 250°C or higher, and even more preferably 255°C or higher, according to ASTM D648, when a 3.2 mm thick strip test piece (length 127 mm, width 12.7 mm) is used. If the deflection temperature under load is lower than 240°C, deformation is likely to occur during the reflow process, which is a processing step for electronic components, and heat resistance tends to be poor. The upper limit of the deflection temperature under load is not particularly limited, but is, for example, 350°C.

[0080] The liquid crystal polyester resin composition of the present invention preferably has a melt viscosity of 3 to 70 Pa·s, more preferably 4 to 50 Pa·s, even more preferably 5 to 30 Pa·s, and particularly preferably 6 to 25 Pa·s, as measured at 350°C using a melt viscosity measuring device with a 1.0 mmφ×10 mm capillary. If the melt viscosity is less than 3 Pa·s, problems such as drooling are likely to occur during injection molding, and if it exceeds 70 Pa·s, the flowability tends to be insufficient.

[0081] The liquid crystal polyester resin composition of the present invention has a 0.1 mm thickness flow length, measured by the method described below, of preferably 10 mm or more, more preferably 12 mm or more, and even more preferably 14 mm or more. If the 0.1 mm thickness flow length is less than 10 mm, defects such as short shots tend to occur when molding small, thin-walled parts. The upper limit of the 0.1 mm thickness flow length is not particularly limited, but is, for example, 50 mm.

[0082] The liquid crystal polyester resin composition of the present invention preferably has a blister incidence rate of 15% or less, more preferably 10% or less, and even more preferably 5% or less, in a step blister test measured by the method described below. Since this test is a severe test, a blister incidence rate of 15% or less is sufficient for practical use. If the blister incidence rate exceeds 15%, blisters may occur even during actual use depending on the molding conditions.

[0083] The liquid crystal polyester resin composition of the present invention has excellent thin-wall fluidity and blister resistance while maintaining the mechanical strength and heat resistance of liquid crystal polyester, and therefore can be used as a molded article, and is particularly suitable for use in electronic parts such as connectors, switches, relays, bobbins, capacitors, coils, motors, fans, test sockets, transformers, camera modules, and antennas. [Example]

[0084] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples in any way.

[0085] In the examples, the crystal melting temperature, tensile strength, tensile elongation at break, Izod impact strength, deflection temperature under load, melt viscosity, 0.1 mm thickness flow length and step blisters were measured and evaluated by the methods described below.

[0086] (1) Crystal melting temperature Using a differential scanning calorimeter (DSC7020 manufactured by Hitachi High-Tech Science Corporation), the endothermic peak temperature (Tm1) observed when measuring at a temperature increase of 20°C / min from room temperature was observed, and then the temperature was held at a temperature 20 to 50°C higher than Tm1 for 10 minutes. Next, the sample was cooled to room temperature at a temperature decrease of 20°C / min, and the peak top temperature of the exothermic peak observed at this time was taken as the crystallization temperature (Tc) of the wholly aromatic liquid crystalline polyester. Further, the endothermic peak was observed when measuring again at a temperature increase of 20°C / min, and the temperature showing the peak top was taken as the crystalline melting temperature (Tm) of the wholly aromatic liquid crystalline polyester.

[0087] (2) Tensile strength Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), injection molding was performed at a cylinder temperature of 350°C and a mold temperature of 70°C to obtain dumbbell-shaped tensile test specimens (ASTM No. 4, thickness 3.2 mm). Tensile tests were performed using an Autograph AG-X plus manufactured by Shimadzu Corporation in accordance with ASTM D638, with a chuck distance of 64.0 mm and a tensile speed of 5 mm / min.

[0088] (3) Tensile elongation at break The same test pieces as those used for measuring the tensile strength were used and the measurement was carried out in the same manner as for the tensile strength.

[0089] (4) Izod impact strength Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), strip-shaped test specimens measuring 127 mm in length, 12.7 mm in width, and 3.2 mm in thickness were molded at a cylinder temperature of 350° C. and a mold temperature of 70° C. The center of each test specimen was cut perpendicular to the longitudinal 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.

[0090] (5) Deflection temperature under load (low load DTUL) Using an injection molding machine (UH1000-110 manufactured by Nissei Plastic Industrial Co., Ltd.), strip-shaped test pieces 127 mm long, 12.7 mm wide, and 3.2 mm thick were molded at a cylinder temperature of 350°C and a mold temperature of 70°C. These were used to measure the mechanical properties in accordance with ASTM D648, at a load of 0.48 MPa and a heating rate of 2°C / min.

[0091] (6) 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 was measured under the conditions of 350°C.

[0092] (7) 0.1 mm thickness flow length Using an injection molding machine (NEX-15-1E manufactured by Nissei Plastic Industrial Co., Ltd.), injection molding was performed using a rectangular bar flow mold measuring 50 mm in length, 2.0 mm in width, and 0.1 mm in thickness under the molding conditions shown in Table 1, and the flow length when the material was filled into the bar flow mold was measured.

[0093] [Table 1]

[0094] (8) Step blisters Plate-shaped test specimens were prepared by injection molding using an injection molding machine (NEX-15-1E, manufactured by Nissei Plastics Co., Ltd.) under the molding conditions listed in Table 2. These plate-shaped test specimens had a plate-shaped portion measuring 24 mm in length, 16 mm in width, and 0.3 mm in thickness. Six convex portions (4 mm in length, 4 mm in width, 0.5 mm in height, total thickness 0.8 mm) were evenly spaced 4 mm apart on one flat surface (arranged in three vertical rows and two horizontal rows). This shape was intentionally designed to facilitate air entrapment in the resin during injection molding, which facilitated the formation of blisters upon heating, making severe testing possible. The plate specimens were left at 23°C and 50% relative humidity for 24 hours, and then reflow-treated using an IR reflow machine (SAI-2604, manufactured by Senju Metal Industry Co., Ltd.) under the following conditions: preheating temperature: 190°C, preheating time: 30-50 seconds, main heating temperature: 250°C or higher, main heating time: 20-30 seconds, and peak temperature: 260-265°C. The occurrence of blisters on the surface was visually counted. The counting method involved drawing lines using a writing implement to divide the plate specimen into six regions centered on six convex portions. The presence or absence of blisters in each region was confirmed, and a score of 1 was assigned for each region if blisters were present, and a score of 0 if not. In other words, the maximum number of blisters counted per plate specimen was 6. Fifteen test pieces (90 areas) were evaluated for each injection speed condition, for a total of 60 test pieces (360 areas in total) under four injection speed conditions. If the blister incidence rate was 0-5%, it was marked as ◎, if it was over 5% to 15%, it was marked as 〇, if it was over 15% to 25%, it was marked as △, and if it was over 25%, it was marked as ×.

[0095] [Table 2]

[0096] The synthesis examples of the liquid crystal polyester resins used in the Examples and Comparative Examples are described below. The abbreviations for the compounds in the synthesis examples are as follows:

[0097] LCP: Liquid crystal polyester resin POB: 4-hydroxybenzoic acid BON6: 6-hydroxy-2-naphthoic acid HQ: Hydroquinone BP: 4,4'-dihydroxybiphenyl TPA: Terephthalic acid NDA: 2,6-naphthalenedicarboxylic acid

[0098] Synthesis Example 1 (LCP1) A reaction vessel equipped with a stirrer with a torque meter and a distillation tube was charged with POB, HQ, BP, TPA, and NDA in a total amount of 6.5 mol in the composition ratio shown in Table 3, and acetic anhydride was further charged in an amount of 1.05 times the moles of the hydroxyl groups (moles) of all monomers, and deacetic acid polymerization was carried out under the following conditions.

[0099] [Table 3]

[0100] The temperature was raised from room temperature to 150°C over 1 hour under a nitrogen gas atmosphere and held at that temperature for 30 minutes. Next, the temperature was rapidly raised to 210°C while distilling off the by-product acetic acid and held at that temperature for 30 minutes. The temperature was then raised to 350°C over 3 hours, and the pressure was reduced to 20 mmHg over 30 minutes. The polymerization reaction was terminated when the specified torque was reached, and the contents were removed from the reactor and crushed to obtain liquid crystal polyester resin pellets. The amount of acetic acid distilled during polymerization was nearly the theoretical value. The crystalline melting temperature (Tm) of the resulting pellets was 308°C, and the melt viscosity measured at 350°C was 10 Pa·s.

[0101] 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 4 so that the total amount was 6.5 mol. Furthermore, acetic anhydride was charged in an amount of 1.03 times the moles of the hydroxyl groups (moles) of all monomers, and deacetic acid polymerization was carried out under the following conditions.

[0102] [Table 4]

[0103] The temperature was raised from room temperature to 150°C in a nitrogen gas atmosphere over one hour and maintained at that temperature for 30 minutes. The temperature was then raised to 350°C over seven hours while distilling off the by-product acetic acid, and the pressure was then reduced to 5 mmHg over 80 minutes. The polymerization reaction was terminated when the specified torque was reached, and the contents of the reactor were removed and crushed to obtain liquid crystal polyester resin pellets. The amount of acetic acid distilled during polymerization was nearly the theoretical value. The crystalline melting temperature (Tm) of the resulting pellets was 335°C, and the melt viscosity measured at 350°C was 18 Pa·s.

[0104] Synthesis Example 3 (LCP3) A reaction vessel equipped with a stirrer with a torque meter and a distillation tube was charged with POB, HQ, BP, TPA, and NDA in the composition ratios shown in Table 5 so that the total amount was 6.5 mol. Furthermore, acetic anhydride was charged in an amount of 1.05 times the moles of the hydroxyl groups (moles) of all the monomers, and deacetic acid polymerization was carried out under the following conditions.

[0105] [Table 5]

[0106] The temperature was raised from room temperature to 150°C over 1 hour under a nitrogen gas atmosphere and held at that temperature for 30 minutes. Next, the temperature was rapidly raised to 210°C while distilling off the by-product acetic acid and held at that temperature for 30 minutes. The temperature was then raised to 350°C over 3 hours, and the pressure was reduced to 20 mmHg over 30 minutes. The polymerization reaction was terminated when the specified torque was reached, and the contents were removed from the reactor and crushed to obtain liquid crystal polyester resin pellets. The amount of acetic acid distilled during polymerization was nearly the theoretical value. The crystalline melting temperature (Tm) of the resulting pellets was 303°C, and the melt viscosity measured at 350°C was 16 Pa·s.

[0107] The plate-like fillers and fibrous fillers used in the examples and comparative examples are shown below. Mica: Yamaguchi Mica Co., Ltd., Mica "AB-25S" (average particle size: 24 μm, aspect ratio: 80) Talc: Fuji Talc Industrial Co., Ltd., talc "RL119" (average particle size: 17 μm, aspect ratio: 8) Glass fiber: Nippon Electric Glass Co., Ltd., ECS03T-747H (average fiber diameter 10.5 μm, average fiber length 3 mm)

[0108] Examples 1 to 7 and Comparative Examples 1 to 3 The synthesized LCP, the plate-like filler, and the glass fiber were blended to the contents (parts by mass) shown in Table 5, and melt-kneaded using a twin-screw extruder (TEX-30 manufactured by Nippon Steel Corporation) at a cylinder temperature of 350°C to obtain pellets of a liquid crystal polyester resin composition. Thereafter, the tensile strength, tensile elongation at break, Izod impact strength, deflection temperature under load, melt viscosity, 0.1 mm thickness flow length, and step blister were measured and evaluated by the above-mentioned methods. The results are shown in Table 5.

[0109] As shown in Table 5, all of the liquid crystal polyester resin compositions of Examples 1 to 7 maintained the mechanical strength and heat resistance of liquid crystal polyester at a certain level, while exhibiting excellent thin-wall fluidity and blister resistance.

[0110] In contrast, the liquid crystal polyester resin compositions of Comparative Examples 1 to 3 were inferior in any one of mechanical strength, heat resistance, thin-wall fluidity, and blister resistance, and did not fully satisfy the balance of performance.

[0111] [Table 6]

Claims

1. Formulas [I] to [V] 【Chemistry 1】 [In the formula, p, q, r, s, and t are the composition ratios (mol %) of the respective repeating units in the liquid crystal polyester resin, and satisfy the following conditions: 15≦p≦30, 5≦q≦25, 15≦r≦35, 10≦s≦30, 10≦t≦30, 1.05≦r / q≦5.0, p+q+r+s+t≧95] and 0.1 to 70 parts by mass of a plate-like filler having an aspect ratio of 3 or more.

2. 2. The liquid crystal polyester resin composition according to claim 1, wherein the platy filler is mica and / or talc.

3. The liquid crystal polyester resin composition according to claim 1, further comprising 0.1 to 70 parts by mass of a fibrous filler per 100 parts by mass of the liquid crystal polyester resin.

4. 4. The liquid crystal polyester resin composition according to claim 3, wherein the fibrous filler is glass fiber.

5. The liquid crystal polyester resin composition according to claim 1, which has a deflection temperature under load of 240°C or higher as measured at a load of 0.48 MPa in accordance with ASTM D648.

6. 2. The liquid crystal polyester resin composition according to claim 1, wherein the Izod impact strength measured in accordance with ASTM D256 using a notched strip specimen having a length of 63.5 mm, a width of 12.7 mm and a thickness of 3.2 mm is 100 J / m or more.

7. A molded article made from the liquid crystal polyester resin composition according to any one of claims 1 to 6.

8. The molded article according to claim 7, wherein the molded article is a part constituting one selected from the group consisting of a connector, a switch, a relay, a bobbin, a capacitor, a coil, a motor, a fan, a test socket, a transformer, a camera module, and an antenna.

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