Liquid crystalline resin composition and connector using same

Abstract

Provided are: a liquid crystalline resin composition which has good fluidity and provides a molded article having excellent low warpage and reduced blisters; and a connector using same.　A liquid crystalline resin composition according to the present invention contains (A) a wholly aromatic polyester, (B) a plate-like filler, and (C) a fibrous filler, wherein the wholly aromatic polyester (A) contains predetermined amounts of constituent units (I)-(V) as essential constituent components, the weight average fiber length of the fibrous filler (C) is 500 μm or less, and the content of the wholly aromatic polyester (A) is 70-85 mass%, the content of the plate-like filler (B) is 10-25 mass%, the content of the fibrous filler (C) is 1.5-8.5 mass%, and the total content of the plate-like filler (B) and the fibrous filler (C) is 15-30 mass%, with respect to the entirety of the liquid crystalline resin composition. A connector according to the present invention includes a molded article of the liquid crystalline resin composition.

Description

Liquid crystal resin composition and connector using the same

[0001] The present invention relates to a liquid crystalline resin composition and a connector using the same.

[0002] Liquid crystal resins have a good balance of excellent mechanical strength, heat resistance, chemical resistance, electrical properties, etc., and also have excellent dimensional stability, and therefore are widely used as high-performance engineering plastics.

[0003] In particular, with the recent trend toward smaller and thinner electronic devices, there is a need for lower heights and narrower pitches in electronic components (connectors, etc.) that make up electronic devices. For example, Patent Document 1 discloses a connector molded from a liquid crystalline resin composition reinforced with mica and glass fibers. Such connectors are used as board-to-board (B to B) connectors, FPC connectors used to connect flexible printed circuit boards (FPCs) and flexible flat cables (FFCs), and the like, which require heat resistance, suppression of warpage deformation, dimensional stability, etc.

[0004] Furthermore, liquid crystal resin compositions can have the problem of blister formation. That is, liquid crystal polymers such as liquid crystal polyesters and liquid crystal polyesteramides have good thermal stability at high temperatures and are therefore often used in materials that require heat treatment at high temperatures. However, when a molded product is left in high-temperature air or liquid for a long period of time, a problem occurs in which small swellings called blisters form on the surface.

[0005] One cause of this phenomenon is that decomposition gases, etc., generated when the liquid crystalline polymer is in a molten state are carried into the molded article, and then, when the molded article is subjected to high-temperature heat treatment, the gases expand and push up the surface of the molded article softened by heating, causing the pushed-up parts to appear as blisters. For example, Patent Document 2 discloses a liquid crystalline resin composition that reduces the occurrence of blisters due to such causes, which contains a liquid crystalline polyester, a specific fatty acid ester, a filler, and a fatty acid metal salt.

[0006] JP 2006-37061 A JP 2009-179693 A

[0007] According to the investigations of the present inventors, when a connector is molded from a conventional liquid crystalline resin composition, the liquid crystalline resin composition has insufficient fluidity and poor processability, making it difficult to manufacture a connector that meets the needs for low height and narrow pitch. Moreover, it is not easy to obtain a molded product that is excellent in a balanced manner in low warpage and blister resistance from a conventional liquid crystalline resin composition.

[0008] The present invention has been made to solve the above-mentioned problems, and its object is to provide a liquid crystalline resin composition with good fluidity that gives molded articles with excellent low warpage and suppressed blister generation, and a connector using the same.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that the above-mentioned problems can be solved by using a liquid crystalline resin composition containing a wholly aromatic polyester containing specific structural units in a specific ratio, a plate-like filler, and a fibrous filler having a weight-average fiber length of 500 μm or less in specific ratios, and have completed the present invention. More specifically, the present invention provides the following.

[0010] (1) A liquid crystalline resin composition comprising (A) a wholly aromatic polyester, (B) a plate-like filler, and (C) a fibrous filler, wherein the (A) wholly aromatic polyester contains the following structural units (I) to (V) as essential structural components, and the (A) wholly aromatic polyester contains: 50 to 75 mol% of structural unit (I), 2 to 8 mol% of structural unit (II), 4.5 to 22 mol% of structural unit (III), 2 to 8 mol% of structural unit (IV), 12.5 to 24 mol% of structural unit (V), and 4 to 10 mol% of the total of the structural units (II) and (IV), the weight average fiber length of the (C) fibrous filler is 500 μm or less, and the (A) wholly aromatic polyester contains 70 to 85 mass% of the total of the liquid crystalline resin composition, The liquid crystal resin composition has a content of the plate-like filler (B) of 10 to 25% by mass, a content of the fibrous filler (C) of 1.5 to 8.5% by mass, and a total content of the plate-like filler (B) and the fibrous filler (C) of 15 to 30% by mass.

[0011] (2) The liquid crystal resin composition according to (1), wherein the total content of the structural units (I) to (V) is 100 mol % based on all structural units in the wholly aromatic polyester (A).

[0012] (3) The liquid crystal resin composition according to (1) or (2), wherein the platy filler (B) is at least one selected from the group consisting of talc and mica.

[0013] (4) The liquid crystal resin composition according to any one of (1) to (3), wherein the fibrous filler (C) is glass fiber.

[0014] (5) The liquid crystal resin composition according to any one of (1) to (4), which is used for a connector.

[0015] (6) Use of the liquid crystal resin composition according to any one of (1) to (5) for producing a connector.

[0016] (7) A connector comprising a molded article of the liquid crystal resin composition according to any one of (1) to (5).

[0017] (8) The connector according to (7), which is a low-profile, narrow-pitch connector.

[0018] (9) The connector according to (8), wherein the low-profile narrow-pitch connector is a board-to-board connector or a connector for a flexible printed circuit board.

[0019] According to the present invention, it is possible to provide a liquid crystalline resin composition having good flowability, which gives a molded article having excellent low warpage and suppressed blister generation, and a connector using the same.

[0020] FIG. 1(a) is a side view showing a molded product molded when measuring the minimum filling pressure of a thin rib in the examples, and FIG. 1(b) is a plan view showing the molded product.

[0021] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0022] <Liquid Crystalline Resin Composition> The liquid crystal resin composition of the present invention contains (A) a wholly aromatic polyester, (B) a plate-like filler, and (C) a fibrous filler.

[0023] [(A) Wholly Aromatic Polyester] The liquid crystal resin composition according to the present invention contains (A) a wholly aromatic polyester. The (A) wholly aromatic polyester can be used singly or in combination of two or more. The (A) wholly aromatic polyester contains the following structural units (I) to (V) as essential structural components, where, relative to all structural units in the (A) wholly aromatic polyester, the content of structural unit (I) is 50 to 75 mol%, the content of structural unit (II) is 2 to 8 mol%, the content of structural unit (III) is 4.5 to 22 mol%, the content of structural unit (IV) is 2 to 8 mol%, the content of structural unit (V) is 12.5 to 24 mol%, and the total content of structural unit (II) and structural unit (IV) is 4 to 10 mol%.

[0024]

[0025] The structural unit (I) is derived from 4-hydroxybenzoic acid (hereinafter also referred to as "HBA"). Component (A) contains 50 to 75 mol% of the structural unit (I) relative to all structural units. When the content of the structural unit (I) is within this range, good fluidity is likely to be achieved. From the standpoint of fluidity, the content of the structural unit (I) relative to all structural units is preferably 52.5 to 70 mol%, more preferably 55 to 65 mol%.

[0026] The structural unit (II) is derived from 6-hydroxy-2-naphthoic acid (hereinafter also referred to as "HNA"). The component (A) contains 2 to 8 mol% of the structural unit (II) relative to all structural units. When the content of the structural unit (II) is within this range, good fluidity is likely to be achieved. From the standpoint of fluidity, the content of the structural unit (II) is preferably 2.5 to 7 mol%, more preferably 3 to 6 mol%, relative to all structural units.

[0027] The structural unit (III) is derived from 1,4-phenylenedicarboxylic acid (hereinafter also referred to as "TA"). Component (A) contains 4.5 to 22 mol% of the structural unit (III) relative to all structural units. When the content of the structural unit (III) is within this range, good fluidity is likely to be achieved. From the standpoint of fluidity, the content of the structural unit (III) is preferably 7.5 to 19.5 mol%, more preferably 10 to 16.5 mol%, relative to all structural units.

[0028] The structural unit (IV) is derived from 1,3-phenylenedicarboxylic acid (hereinafter also referred to as "IA"). The component (A) contains 2 to 8 mol% of the structural unit (IV) relative to all structural units. When the content of the structural unit (IV) is within this range, good fluidity is likely to be achieved. From the standpoint of fluidity, the content of the structural unit (IV) is preferably 2.5 to 7 mol%, more preferably 3 to 6 mol%, relative to all structural units.

[0029] The structural unit (V) is derived from 4,4'-dihydroxybiphenyl (hereinafter also referred to as "BP"). The component (A) contains 12.5 to 24 mol% of the structural unit (V) relative to all structural units. When the content of the structural unit (V) is within this range, good fluidity is likely to be achieved. From the standpoint of fluidity, the content of the structural unit (V) relative to all structural units is preferably 14.5 to 22 mol%, more preferably 16 to 21 mol%.

[0030] The (A) wholly aromatic polyester contains 4 to 10 mol% of the structural unit (II) and the structural unit (IV) in total relative to all structural units. When this total content is within this range, blistering is likely to be suppressed in molded articles of the liquid crystal resin composition. From the viewpoint of blister resistance, this total content is preferably 5.5 to 9.5 mol%, more preferably 7 to 9 mol%, relative to all structural units.

[0031] The component (A) has excellent fluidity because it contains specific structural units (I) to (V) in specific amounts relative to the total structural units. In the (A) wholly aromatic polyester, from the viewpoint of fluidity, the total content of the structural units (I) to (V) relative to the total structural units is preferably 80 to 100 mol%, more preferably 90 to 100 mol%, even more preferably 95 to 100 mol%, and most preferably 100 mol%. Therefore, the liquid crystalline resin of the present invention may contain a structural unit other than the structural units (I) to (V) (hereinafter also referred to as "structural unit (Z)"). In the (A) wholly aromatic polyester, from the viewpoint of fluidity, the content of the structural unit (Z) relative to the total structural units is preferably 0 to 20 mol%, more preferably 0 to 10 mol%, even more preferably 0 to 5 mol%, and most preferably 0 mol%.

[0032] Examples of the structural unit (Z) include structural units derived from one or more types selected from the group consisting of 2,6-naphthalenedicarboxylic acid, hydroquinone, and derivatives thereof. Hereinafter, a monomer that derives the structural unit (Z) will also be referred to as monomer (Z). In the (A) wholly aromatic polyester, the structural unit (Z) may be used alone, or two or more types may be used in combination.

[0033] Next, a method for producing the wholly aromatic polyester of the present invention will be described. The wholly aromatic polyester of the present invention is polymerized using a direct polymerization method, a transesterification method, or the like. For the polymerization, a melt polymerization method, a solution polymerization method, a slurry polymerization method, a solid-state polymerization method, or a combination of two or more of these methods is used, and a melt polymerization method or a combination of a melt polymerization method and a solid-state polymerization method is preferably used.

[0034] In the present invention, an acylating agent for the polymerizable monomer or a monomer having an activated terminal as an acid chloride derivative can be used in the polymerization. Examples of the acylating agent include fatty acid anhydrides such as acetic anhydride.

[0035] Various catalysts can be used in these polymerizations, and examples thereof include metal salt catalysts such as fatty acid metal salt catalysts and organic compound catalysts. Typical examples include metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, and tris(2,4-pentanedionato)cobalt(III), and organic compound catalysts such as 1-methylimidazole and 4-dimethylaminopyridine.

[0036] The reaction conditions are, for example, a reaction temperature of 200 to 380°C and a final pressure of 0.1 to 760 Torr (i.e., 13 to 101,080 Pa). In particular, in the case of a melting reaction, the reaction temperature is, for example, 260 to 380°C, preferably 300 to 360°C, and the final pressure is, for example, 1 to 100 Torr (i.e., 133 to 13,300 Pa), preferably 1 to 50 Torr (i.e., 133 to 6,670 Pa).

[0037] The reaction can be initiated by charging all the raw material monomers (HBA, HNA, TA, IA, and BP), the acylating agent, and the catalyst into the same reaction vessel (single-stage system), or by acylating the hydroxyl groups of the raw material monomers HNA, HBA, and BP with the acylating agent and then reacting them with the carboxyl groups of TA and IA (two-stage system).

[0038] The melt polymerization is carried out by starting pressure reduction and maintaining a predetermined reduced pressure after the reaction system has reached a predetermined temperature. After the torque of the agitator has reached a predetermined value, an inert gas is introduced, and the pressure is increased from reduced pressure to normal pressure and then to a predetermined pressurized state, and the wholly aromatic polyester is discharged from the reaction system.

[0039] The wholly aromatic polyester produced by the above polymerization method can be further subjected to solid-state polymerization by heating in an inert gas at normal or reduced pressure to increase the molecular weight. Preferred conditions for the solid-state polymerization reaction are a reaction temperature of 230 to 350°C, preferably 260 to 330°C, and a final pressure of 10 to 760 Torr (i.e., 1,330 to 101,080 Pa).

[0040] Next, the properties of the wholly aromatic polyester will be described. The wholly aromatic polyester of the present invention exhibits optical anisotropy when molten. When a resin exhibits optical anisotropy when molten, it means that the resin is a liquid crystalline resin. The wholly aromatic polyester of the present invention has both thermal stability and easy processability.

[0041] The melt anisotropy can be confirmed by a conventional polarization inspection method using crossed polarizers. More specifically, melt anisotropy can be confirmed by melting a sample placed on a Linkam hot stage using an Olympus polarizing microscope and observing it at 150x magnification under a nitrogen atmosphere. Wholly aromatic polyesters are optically anisotropic and transmit light when inserted between crossed polarizers. If a sample is optically anisotropic, polarized light will transmit even when it is in a molten, static liquid state, for example.

[0042] Nematic wholly aromatic polyesters exhibit a significant decrease in viscosity above their melting point, and therefore, the fact that they exhibit liquid crystallinity at or above their melting point is generally an indicator of processability. From the standpoint of heat resistance, a melting point that is as high as possible is preferable, but considering factors such as thermal degradation during melt processing of wholly aromatic polyesters and the heating capacity of extruders, a melting point of 360°C or less is a preferable guideline. The melting point is more preferably 300 to 360°C, and even more preferably 320 to 358°C.

[0043] The melt viscosity of the wholly aromatic polyester obtained by the above method is not particularly limited. Generally, the melt viscosity at a cylinder temperature 10 to 30° C. higher than the melting point is 1000 s at a shear rate of 1000 s. －１ A viscosity of 5 Pa·s or more and 85 Pa·s or less can be used. However, a viscosity that is too high is not preferable because it significantly deteriorates the flowability. In this specification, the melt viscosity is a value obtained by measurement in accordance with ISO 11443.

[0044] The content of the wholly aromatic polyester (A) in the liquid crystal resin composition of the present invention is 70 to 85% by mass, preferably 72 to 80% by mass, and more preferably 73 to 77% by mass. The content of the component (A) within the above range is preferable in terms of flowability, heat resistance, etc.

[0045] [(B) Plate-like filler] The liquid crystalline resin composition according to the present invention contains a plate-like filler. By containing the plate-like filler in the liquid crystalline resin composition according to the present invention, it is easy to obtain a molded article having suppressed anisotropy while maintaining excellent mechanical strength. The plate-like filler can be used alone or in combination of two or more.

[0046] The median diameter of component (B) is preferably 1 to 50 μm. When the median diameter is within the above range, it is easier to obtain a molded article with suppressed anisotropy from the resulting composition while maintaining excellent mechanical strength. The median diameter is preferably 5 to 40 μm, more preferably 8 to 30 μm. In this specification, the median diameter of component (B) refers to the volume-based median value measured by a laser diffraction / scattering particle size distribution measurement method. The median diameter of component (B) in the liquid crystalline resin composition is measured by applying the above method to the component (B) remaining after heating the liquid crystalline resin composition to incinerate it at 600°C for 2 hours.

[0047] The content of the (B) plate-like filler is 10 to 25% by mass relative to the total liquid crystal resin composition of the present invention. When the content of the (B) plate-like filler is within the above range, it is easier to obtain a molded article with reduced anisotropy from the resulting composition while maintaining excellent mechanical strength. The content of the (B) plate-like filler is preferably 15 to 23% by mass, more preferably 17.5 to 22% by mass.

[0048] Examples of the plate-like filler in the present invention include talc, mica, glass flakes, various metal foils, etc. From the viewpoint of suppressing the anisotropy of a molded article obtained from the liquid crystalline resin composition without deteriorating the fluidity of the liquid crystalline resin composition, one or more selected from the group consisting of talc and mica are preferred, and mica is more preferred.

[0049] [Talc] The talc that can be used in the present invention is a talc containing Fe, ２ O ３ , Al ２ O ３ and CaO total content is 2.5 mass% or less, and Fe ２ O ３ and Al ２ O ３ The total content of these is preferably more than 1.0 mass % and not more than 2.0 mass %, and the CaO content is less than 0.5 mass %. That is, the talc that can be used in the present invention is preferably one in which the main component, SiO ２ and MgO, as well as Fe ２ O ３ , Al ２ O ３ and CaO, each of which may be contained within the above-mentioned content ranges.

[0050] In the above talc, Fe ２ O ３ , Al ２ O ３ When the total content of Fe and CaO is 2.5% by mass or less, the moldability of the liquid crystal resin composition and the heat resistance of a molded article formed from the liquid crystal resin composition are unlikely to deteriorate. ２ O ３ , Al ２ O ３The total content of Si and CaO is preferably 1.0 mass % or more and 2.0 mass % or less.

[0051] Among the above talc, Fe ２ O ３ and Al ２ O ３ Talc having a total content of more than 1.0 mass % is readily available. ２ O ３ and Al ２ O ３ When the total content of Fe is 2.0 mass % or less, the moldability of the liquid crystal resin composition and the heat resistance of the molded article molded from the liquid crystal resin composition are unlikely to deteriorate. ２ O ３ and Al ２ O ３ The total content of is preferably more than 1.0 mass % and 1.7 mass % or less.

[0052] Furthermore, when the CaO content in the talc is less than 0.5% by mass, the moldability of the liquid crystal resin composition and the heat resistance of a molded article formed from the liquid crystal resin composition are unlikely to deteriorate, and therefore the CaO content is preferably 0.01% by mass or more and 0.4% by mass or less.

[0053] [Mica] Mica is a pulverized silicate mineral containing aluminum, potassium, magnesium, sodium, iron, etc. Examples of mica that can be used in the present invention include muscovite, phlogopite, biotite, and artificial mica, with muscovite being preferred among these because of its good hue and low cost.

[0054] In addition, wet grinding and dry grinding are known as methods for grinding minerals in the production of mica. The wet grinding method involves roughly grinding mica raw ore in a dry grinder, adding water to form a slurry, wet grinding the resulting material, and then dehydrating and drying. Compared to the wet grinding method, the dry grinding method is a more common method with lower costs, but the wet grinding method makes it easier to grind minerals thinly and finely. It is preferable to use thin, finely ground material in the present invention because it allows the production of mica having the above-mentioned median diameter and the preferred thickness described below. Therefore, it is preferable to use mica produced by the wet grinding method in the present invention.

[0055] In addition, since the wet grinding method requires a step of dispersing the material to be ground in water, it is common to add a flocculating sedimentation agent and / or a sedimentation aid to the material to be ground in order to improve the dispersion efficiency of the material. Examples of flocculating sedimentation agents and sedimentation aids that can be used in the present invention include polyaluminum chloride, aluminum sulfate, ferrous sulfate, ferric sulfate, copper chloride, polyiron sulfate, polyferric chloride, iron-silica inorganic polymer flocculant, ferric chloride-silica inorganic polymer flocculant, slaked lime (Ca(OH) ２ ), caustic soda (NaOH), soda ash (Na ２ CO ３ ) and the like. These flocculating sedimentation agents and sedimentation aids have an alkaline or acidic pH. The mica used in the present invention is preferably one that has not been treated with a flocculating sedimentation agent and / or sedimentation aid during wet grinding. When mica that has not been treated with a flocculating sedimentation agent and / or sedimentation aid is used, decomposition of the polymer in the liquid crystalline resin composition is unlikely to occur, and large amounts of gas generation and a decrease in the molecular weight of the polymer are unlikely to occur, making it easier to maintain the performance of the resulting molded product better.

[0056] The thickness of the mica that can be used in the present invention is preferably 0.01 to 1 μm, particularly preferably 0.03 to 0.3 μm, as measured by observation with an electron microscope. If the thickness of the mica is 0.01 μm or more, the mica is less likely to crack during melt processing of the liquid crystalline resin composition, which is preferable because the rigidity of the molded article may be easily improved. If the thickness of the mica is 1 μm or less, the effect of improving the rigidity of the molded article is likely to be sufficient, which is preferable.

[0057] The mica that can be used in the present invention may be surface-treated with a silane coupling agent or the like, and / or may be granulated with a binder to form granules.

[0058] [(C) Fibrous Filler] The liquid crystalline resin composition of the present invention contains (C) a fibrous filler, which can impart sufficient blister resistance to a molded article of the liquid crystalline resin composition. (C) The fibrous filler can be used alone or in combination of two or more.

[0059] The weight-average fiber length of the (C) fibrous filler is 500 μm or less, preferably 70 to 350 μm, and more preferably 100 to 250 μm. When the weight-average fiber length is 500 μm or less, the liquid crystal resin composition of the present invention tends to have sufficient fluidity. In this specification, the weight-average fiber length of the (C) fibrous filler is determined by capturing 10 stereomicroscope images of the (C) fibrous filler from a CCD camera onto a PC, and then using an image measuring device to process the images. The average fiber length is measured for 100 fibrous fillers per stereomicroscope image, i.e., a total of 1,000 fibrous fillers. The average fiber length of the (C) fibrous filler in the liquid crystal resin composition is measured by applying the above-mentioned method to the remaining (C) fibrous filler after heating the liquid crystal resin composition to 600°C for 2 hours and incinerating it.

[0060] The fiber diameter of the (C) fibrous filler is not particularly limited and may be, for example, 20 μm or less, or may be 5 to 15 μm. In this specification, the fiber diameter of the (C) fibrous filler is determined by observing the (C) fibrous filler with a scanning electron microscope and measuring the fiber diameters of 30 pieces of (C) fibrous filler, and the average value is used. The fiber diameter of the (C) fibrous filler in the liquid crystalline resin composition is measured by applying the above-mentioned method to the remaining (C) fibrous filler after heating the liquid crystalline resin composition to ashed it at 600°C for 2 hours.

[0061] Any fiber can be used as long as it satisfies the above-mentioned shape, but examples of the fibrous filler (C) include inorganic fibrous materials such as glass fiber, milled fiber, carbon fiber, asbestos fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, and fibrous materials of metals such as stainless steel, aluminum, titanium, copper, brass, etc. In the present invention, from the viewpoint of mechanical strength, it is preferable to use glass fiber as component (C).

[0062] The content of the fibrous filler (C) is 1.5 to 8.5 mass %, preferably 2.5 to 8 mass %, more preferably 3 to 7.5 mass %, based on the total mass of the liquid crystal resin composition of the present invention. When the content of the fibrous filler (C) is within the above range, the fluidity of the liquid crystal resin composition is sufficiently ensured, and the occurrence of blisters in a molded product of the liquid crystal resin composition is easily suppressed.

[0063] The total content of the (B) plate-like filler and the (C) fibrous filler relative to the total liquid crystal resin composition of the present invention is 15 to 30% by mass. When this total content is within this range, the fluidity of the liquid crystal resin composition is maintained while the mechanical strength of the molded product is likely to be improved. The total content is preferably 20 to 28% by mass, more preferably 23 to 27% by mass.

[0064] [Other Components] To the liquid crystalline resin composition of the present invention, other polymers, other fillers, and known substances generally added to synthetic resins, i.e., stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, flame retardants, colorants such as dyes and pigments, lubricants, mold release agents, crystallization accelerators, crystal nucleating agents, etc., may be added as appropriate depending on the required performance, within a range that does not impair the effects of the present invention.

[0065] Examples of other polymers include epoxy group-containing styrene polymers and non-epoxy group-containing olefin polymers. Examples of epoxy group-containing styrene polymers include known epoxy group-containing styrene polymers, including copolymers composed of repeating units derived from styrenes and repeating units derived from glycidyl esters of α,β-unsaturated acids. Examples of epoxy group-free olefin polymers include polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, polybutadiene, polyisoprene, polychloroprene, ethylene-propylene-butadiene copolymer, ethylene-propylene-isoprene copolymer, ethylene-propylene-chloroprene copolymer, ethylene-ethyl acrylate copolymer, and ethylene-vinyl acetate copolymer.

[0066] The other fillers refer to fillers other than the (B) plate-like filler and the (C) fibrous filler, and examples thereof include particulate fillers such as silica; carbon black; and the like.

[0067] [Preparation of Liquid Crystalline Resin Composition] The preparation of the resin composition of the present invention is not particularly limited. For example, the liquid crystal resin composition is prepared by blending the above-mentioned components (A), (B), and (C), and optionally other components, and melt-kneading them using a single-screw or twin-screw extruder.

[0068] [Liquid Crystalline Resin Composition] From the viewpoint of fluidity, the melt viscosity of the liquid crystal resin composition of the present invention obtained as described above is preferably 100 Pa·s or less, more preferably 90 Pa·s or less, and even more preferably 85 Pa·s or less. The lower limit of the melt viscosity is not particularly limited, and may be 5 Pa·s or more, 10 Pa·s or more, or 20 Pa·s or more. One of the features of the liquid crystal resin composition of the present invention is that it has high fluidity when melted and excellent moldability. In this specification, the melt viscosity is defined as the viscosity at a cylinder temperature 10 to 30°C higher than the melting point of the liquid crystal resin, a shear rate of 1000 sec －１ The value obtained by the measurement method in accordance with ISO 11443 under the above conditions is adopted.

[0069] <Connector> The liquid crystalline resin composition can be used for a connector. More specifically, the liquid crystalline resin composition can be used to produce a connector. That is, a connector can be produced using the liquid crystalline resin composition. The connector of the present invention includes a molded article of the liquid crystalline resin composition of the present invention. The molded article of the liquid crystalline resin composition of the present invention has excellent low warpage and suppressed blister generation, and can therefore be suitably used as a high-performance connector with excellent low warpage and blister resistance. The molded article can be obtained by molding the liquid crystalline resin composition of the present invention. The molding method is not particularly limited, and examples thereof include injection molding.

[0070] The connector is not particularly limited, and examples thereof include low-profile, narrow-pitch connectors, coaxial connectors, micro SIM connectors, and micro SD connectors. Among these, low-profile, narrow-pitch connectors are preferred. The low-profile, narrow-pitch connector is not particularly limited, and examples thereof include board-to-board connectors (also known as "BtoB connectors") and connectors for flexible printed circuit boards (used to connect flexible printed circuit boards (FPCs) and flexible flat cables (FFCs), and also known as "FPC connectors"). Among these, low-profile, narrow-pitch connectors that are board-to-board connectors or connectors for flexible printed circuit boards and have a pitch distance of 0.5 mm or less, a total product length of 3.5 mm or more but less than 30 mm, and a product height of 1.5 mm or less are preferred.

[0071] The molding method for obtaining the connector of the present invention is not particularly limited, and it is preferable to select molding conditions that do not cause residual internal stress in order to prevent deformation of the connector, etc. In order to lower the filling pressure and reduce the residual internal stress of the connector, the cylinder temperature of the molding machine is preferably a temperature equal to or higher than the melting point of the liquid crystalline resin.

[0072] The mold temperature is preferably 70 to 100°C. A low mold temperature is undesirable because the liquid crystalline resin composition filled in the mold may have poor flow. A high mold temperature is undesirable because it may cause problems such as the generation of flash. The injection speed is preferably 150 mm / sec or higher. If the injection speed is low, there is a possibility that only an unfilled molded product will be obtained, and even if a completely filled molded product is obtained, the molded product will have a high filling pressure and large residual internal stress, and there is a possibility that only a connector with poor flatness will be obtained.

[0073] The connector of the present invention has excellent low warpage properties and suppresses the occurrence of blisters.

[0074] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0075] <Totally Aromatic Polyester> Polymer 1 After charging the following raw materials into a polymerization vessel, the temperature of the reaction system was raised to 140°C and allowed to react at 140°C for 1 hour. The temperature was then raised further to a final polymerization temperature of 335°C over a 3.5-hour heating period, and the pressure was then reduced to 5 Torr (i.e., 667 Pa) over 20 minutes, during which melt polymerization was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling components. After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from reduced pressure to normal pressure and then to pressurized pressure. The polymer was discharged from the bottom of the polymerization vessel, and the strands were pelletized to obtain the target polymer as pellets. The melting point of the resulting polymer was 320°C. 4-Hydroxybenzoic acid (HBA): 498 g (61 mol%), 6-hydroxy-2-naphthoic acid (HNA): 44 g (4 mol%), 1,4-phenylenedicarboxylic acid (TA): 142 g (14.5 mol%), 1,3-phenylenedicarboxylic acid (IA): 30 g (3 mol%), 4,4'-dihydroxybiphenyl (BP): 192 g (17.5 mol%), fatty acid metal salt catalyst (potassium acetate catalyst): 120 mg, acylating agent (acetic anhydride): 627 g

[0076] [Method of measuring melting point] Using a DSC manufactured by TA Instruments, a polymer was heated from room temperature at a temperature increase rate of 20°C / min, and the endothermic peak temperature (Tm1) observed when this was measured. The polymer was then held at a temperature of (Tm1+40)°C for 2 minutes, cooled to room temperature at a temperature decrease rate of 20°C / min, and then heated again at a temperature increase rate of 20°C / min. The endothermic peak temperature (Tm2) observed when this was measured was determined as the melting point of the polymer.

[0077] Polymers 2 to 10 Polymers were obtained in the same manner as Polymer 1, except that the types of raw material monomers, the charging ratios (mol %), the final polymerization temperatures, and the heating times were as shown in Table 1 or Table 2. The melting points of the respective polymers are also as shown in Table 1 or Table 2.

[0078] <Materials other than wholly aromatic polyester> Mica: AB-25S (manufactured by Yamaguchi Mica Co., Ltd., mica, median diameter 25.0 μm) Talc: Crown Talc PP (manufactured by Matsumura Sangyo Co., Ltd., talc, median diameter 14.6 μm) Glass fiber 1: trade name PF70E001 (manufactured by Nitto Boseki Co., Ltd., fiber diameter 10 μm, average fiber length 70 μm (manufacturer's nominal value)) Glass fiber 2: trade name EPH150M-01N (manufactured by Nippon Electric Glass Co., Ltd., fiber diameter 10.5 μm, average fiber length 150 μm (manufacturer's nominal value)) Glass fiber 3: trade name ECS03T-786H (manufactured by Nippon Electric Glass Co., Ltd., chopped strand, fiber diameter 10 μm, length 3 mm)

[0079] <Production of Liquid Crystalline Resin Composition> The above components were melt-kneaded in the proportions (% by mass) shown in Table 1 or Table 2 using a twin-screw extruder (TEX30α type, manufactured by The Japan Steel Works, Ltd.) at the following cylinder temperatures to obtain liquid crystal resin composition pellets. [Production conditions] Cylinder temperature: 350°C (Examples 1 to 10 and Comparative Examples 1 to 4, 8 to 10) 370°C (Comparative Examples 5 to 7)

[0080] <Weight-Average Fiber Length> The weight-average fiber length of the glass fibers in the liquid crystalline resin composition was measured by the following method. Five grams of liquid crystalline resin composition pellets were heated at 600°C for two hours and incinerated. The incineration residue was thoroughly dispersed in a 5% by mass polyethylene glycol aqueous solution and then transferred to a Petri dish with a dropper, and the glass fibers were observed under a stereomicroscope. Ten stereomicroscope images of the glass fibers were imported from a CCD camera to a PC, and the fiber lengths of 100 glass fibers per stereomicroscope image, i.e., a total of 1,000 glass fibers, were measured using an image measuring device (LUZEXFS, manufactured by Nireco Corporation) via image processing. The average of the measured values ​​was used as the weight-average fiber length of the glass fibers. The results are shown in Tables 1 and 2.

[0081] <Minimum filling pressure for thin rib> A liquid crystalline resin composition was injection molded under the following molding conditions to obtain the molded article shown in Figure 1. When injection molding the molded article of Figure 1, the minimum injection filling pressure required to obtain a good molded article that was completely formed up to the rightmost end was measured as the minimum filling pressure. The results are shown in Tables 1 and 2. However, when the minimum filling pressure exceeded 140 MPa, it was indicated that filling was not possible. [Molding conditions] Molding machine: Sumitomo Heavy Industries, Ltd., SE-30DUZ Cylinder temperature: 370°C Mold temperature: 90°C Injection speed: 300 mm / sec

[0082] <Flatness> Five flat test pieces measuring 80 mm x 80 mm x 1 mm were prepared by injection molding the liquid crystalline resin composition under the following molding conditions. The first flat test piece obtained was placed on a horizontal surface, and the height from the horizontal plane was measured at nine locations on the flat test piece using a CNC image measuring instrument (QuickVision 404PRO) manufactured by Mitutoyo Corporation. The average height was calculated from the obtained measurements. The height was measured at the positions corresponding to the vertices of a square with sides of 74 mm placed on the main surface of the flat test piece so that the distance from each side of the main surface was 3 mm, the midpoints of each side of the square, and the intersection of the two diagonals of the square. The height from the horizontal plane was the same as the average height, and the plane parallel to the horizontal plane was used as the reference plane. From the heights measured at the nine locations, the maximum height and the minimum height from the reference plane were selected, and the difference between them was calculated. The above difference was calculated for the other four flat test pieces in the same manner, and the five obtained values ​​were averaged to obtain the flatness value before reflow. The results are shown in Tables 1 and 2. [Molding conditions] Molding machine: Sumitomo Heavy Industries, Ltd., SE-100DU Cylinder temperature: 350°C (Examples 1 to 10 and Comparative Examples 1 to 4, 8 to 10) 370°C (Comparative Examples 5 to 7) Mold temperature: 80°C Injection speed: 33 mm / sec Holding pressure: 60 MPa

[0083] IR reflow was performed under the following conditions, and the flatness was measured by the above-mentioned method to determine the flatness after reflow. The results are shown in Tables 1 and 2. [IR reflow conditions] Measuring device: Large tabletop reflow soldering device RF-300 (using far-infrared heater) manufactured by Japan Pulse Technology Research Institute Sample feed speed: 140 mm / sec Time passing through reflow furnace: 5 minutes Temperature condition in preheat zone: 150°C Temperature condition in reflow zone: 225°C Peak temperature: 287°C

[0084] <Blister Temperature> The pellets of the Examples and Comparative Examples were molded using a molding machine (SE100DU manufactured by Sumitomo Heavy Industries, Ltd.) under the following molding conditions to obtain a molded article having a weld portion and dimensions of 12.5 mm x 120 mm x 0.8 mm. This molded article was divided into two at the weld portion, and each of the obtained pieces was used as a specimen, which was then clamped in a hot press at a predetermined temperature for 5 minutes. Thereafter, the surface of the specimen was visually inspected for the occurrence of blisters. The blister temperature was defined as the highest temperature at which no blisters occurred. The predetermined temperature was set in 10°C increments within the range of 200 to 300°C. The blister resistance of the molded articles was evaluated according to the following criteria. The results are shown in Tables 1 and 2. ∘ (Good): The blister temperature was 250°C or higher. × (Poor): The blister temperature was less than 250°C. [Molding conditions] Cylinder temperature: 350°C (Examples 1 to 10 and Comparative Examples 1 to 4, 8 to 10) 370°C (Comparative Examples 5 to 7) Mold temperature: 90°C Injection speed: 33 mm / sec

[0085]

[0086]

[0087] As can be seen from Tables 1 and 2, in the examples, the minimum filling pressure of the thin rib was 140 MPa or less, the flatness before reflow was 2.0 mm or less, the flatness after reflow was 4.0 mm or less, and the blister resistance was good. Therefore, it was confirmed that the liquid crystalline resin composition according to the present invention has good fluidity, and that the connector including a molded product of this liquid crystalline resin composition has excellent low warpage and suppresses the occurrence of blistering.

Claims

1. A liquid crystalline resin composition comprising (A) a wholly aromatic polyester, (B) a plate-like filler, and (C) a fibrous filler, wherein the (A) wholly aromatic polyester contains the following structural units (I) to (V) as essential structural components, and relative to all structural units in the (A) wholly aromatic polyester, the content of structural unit (I) is 50 to 75 mol%, the content of structural unit (II) is 2 to 8 mol%, the content of structural unit (III) is 4.5 to 22 mol%, the content of structural unit (IV) is 2 to 8 mol%, the content of structural unit (V) is 12.5 to 24 mol%, and the total content of structural units (II) and (IV) is 4 to 10 mol%, the weight average fiber length of the (C) fibrous filler is 500 μm or less, and the content of the (A) wholly aromatic polyester relative to the entire liquid crystalline resin composition is 70 to 85 mass%, The liquid crystal resin composition has a content of the plate-like filler (B) of 10 to 25% by mass, a content of the fibrous filler (C) of 1.5 to 8.5% by mass, and a total content of the plate-like filler (B) and the fibrous filler (C) of 15 to 30% by mass.

2. The liquid crystal resin composition according to claim 1, wherein the total content of the structural units (I) to (V) is 100 mol % based on all structural units in the wholly aromatic polyester (A).

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

4. The liquid crystal resin composition according to claim 1 or 2, wherein the fibrous filler (C) is glass fiber.

5. The liquid crystal resin composition according to claim 1 or 2, which is used for a connector.

6. Use of the liquid crystal resin composition according to claim 1 or 2 for producing a connector.

7. A connector comprising a molded article of the liquid crystalline resin composition according to claim 1 or 2.

8. The connector according to claim 7, which is a low-profile, narrow-pitch connector.

9. The connector according to claim 8, wherein the low-profile, narrow-pitch connector is a board-to-board connector or a connector for flexible printed circuit boards.

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