TWI865469B - Liquid crystal resin composition and connector of molded product containing the same - Google Patents

Abstract

Provided is a liquid crystal resin composition having excellent heat resistance and mechanical strength, capable of suppressing warping and deformation during the manufacture of a connector, and having good fluidity, and a connector comprising a molded product of the liquid crystal resin composition.

The liquid crystal resin composition of the present invention comprises (A) a liquid crystal resin, (B) fibrous wollastonite and (C) mica, wherein the aspect ratio of the aforementioned (B) fibrous wollastonite is greater than 8, and wherein relative to the entirety of the aforementioned liquid crystal resin composition, the content of the aforementioned (A) liquid crystal resin is 62.5-72.5% by mass, the content of the aforementioned (B) fibrous wollastonite is 2.5-15% by mass, the content of the aforementioned (C) mica is 17.5-30% by mass, and the total content of the aforementioned (B) fibrous wollastonite and the aforementioned (C) mica is 27.5-37.5% by mass.

Description

Liquid crystal resin composition and molded product containing the liquid crystal resin composition Connector

The present invention relates to a liquid crystal resin composition and a connector of a molded product containing the liquid crystal resin composition.

Liquid crystal resin is a thermoplastic resin with excellent dimensional accuracy and fluidity. Due to the above characteristics, liquid crystal resin has been often used as a material for various electronic components.

In particular, in recent years, as electronic devices have become smaller and thinner, there has been a demand for thinning and narrowing the intercept of electronic components (connectors, etc.) that constitute electronic devices. For example, Patent Document 1 discloses a connector formed and molded by a liquid crystal resin composition reinforced with mica and glass fibers. The above connector is used as a substrate-to-substrate connector that requires heat resistance, suppression of warping deformation, fluidity, dimensional stability, etc., or a flexible printed circuit board connector used to connect a flexible printed circuit (FPC) and a flexible flat cable (FFC).

[Prior art literature]

[Patent Literature]

[Patent document 1] Japanese Patent Publication No. 2006-37061

However, when attempting to use conventional liquid crystal resin compositions for molding as connectors, the compositions have insufficient heat resistance, mechanical strength, suppression of warping deformation, and fluidity, and poor processability, making it difficult to produce thinned and narrow-intercept connectors that meet the requirements for thinning and narrowing of the intercept.

The present invention is completed in view of the above situation, and its purpose is to provide a liquid crystal resin composition with excellent heat resistance and mechanical strength, which can suppress warping and deformation during the manufacture of the connector and has good fluidity, and to provide a connector comprising a molded product of the liquid crystal resin composition.

The inventors of the present invention have found that the above-mentioned problems can be solved by combining liquid crystal resin, fibrous wollastonite, and mica in predetermined contents and setting the aspect ratio of the fibrous wollastonite to be within a predetermined range. Specifically, the present invention provides the following contents.

(1) A liquid crystal resin composition comprising (A) a liquid crystal resin, (B) fibrous wollastonite and (C) mica, wherein the aspect ratio of the fibrous wollastonite (B) is greater than 8, and wherein the content of the liquid crystal resin (A) is 62.5-72.5% by mass, the content of the fibrous wollastonite (B) is 2.5-15% by mass, the content of the mica (C) is 17.5-30% by mass, and the total content of the fibrous wollastonite (B) and the mica (C) is 27.5-37.5% by mass relative to the entire liquid crystal resin composition.

(2) The liquid crystal resin composition as described in (1) is used for connectors with a total length of less than 30 mm and a height of less than 5 mm.

(3) A connector comprising a molded product of the liquid crystal resin composition described in (1) or (2), wherein the total length of the product is less than 30 mm and the height of the product is less than 5 mm.

(4) The connector as described in (3), which is a thinned narrow-pitch connector.

(5) A connector as described in (3) or (4), which is a thinned narrow-pitch connector for substrate-to-substrate connectors or flexible brush circuit board connectors, wherein the distance between the pitches is less than 0.5 mm, the total length of the product is more than 3.5 mm and less than 30 mm, and the product height is less than 1.5 mm.

According to the present invention, a liquid crystal resin composition having excellent heat resistance and mechanical strength, capable of suppressing warping and deformation during the manufacture of the connector, and having good fluidity is provided, as well as a connector comprising a molded product of the liquid crystal resin composition.

[Figure 1] shows a diagram of a molded FPC connector in an embodiment. In addition, the units of the values in the figure are mm.

[Figure 2] is a diagram showing the measurement points for warping measurement of the FPC connector in the embodiment.

The following is a detailed description of the implementation of the present invention.

[Liquid crystal resin composition]

The liquid crystal resin composition according to the present invention includes a liquid crystal resin, fibrous wollastonite, and mica at predetermined contents, and the aspect ratio of the fibrous wollastonite is greater than 8. The components constituting the liquid crystal resin composition according to the present invention are described below.

[(A) Liquid crystal resin]

The (A) liquid crystal resin used in the present invention refers to a melt-processable polymer having the property of forming an optically anisotropic melt phase. The property of the anisotropic melt phase can be confirmed by a commonly used polarization inspection method using orthogonal polarizers. More specifically, the anisotropic melt phase can be confirmed by observing a melt sample placed on a Leitz hot stage at a magnification of 40 times in a nitrogen atmosphere using a Leitz polarizing microscope. When the liquid crystal resin used in the present invention is inspected between orthogonal polarizers, polarized light is normally transmitted even in a molten static state, showing optical anisotropy.

The type of the liquid crystal resin (A) as mentioned above is not particularly limited, and aromatic polyesters and/or aromatic polyester amides are preferred. Furthermore, polyesters partially containing aromatic polyesters and/or aromatic polyester amides in the same molecular chain can also be included in the above range. As the liquid crystal resin (A), it is preferred to use a liquid crystal resin having a logarithmic viscosity (IV) of at least about 2.0 dl/g when dissolved in pentafluorophenol at a concentration of 0.1 mass % at 60°C, and it is more preferred to use a liquid crystal resin having a logarithmic viscosity (IV) of 2.0~10.0 dl/g.

As the aromatic polyester or aromatic polyester amide suitable for the (A) liquid crystal resin of the present invention, an aromatic polyester or aromatic polyester amide having repeating units derived from aromatic hydroxycarboxylic acid as a constituent component is particularly preferred.

More specifically, there can be listed (1) polyesters mainly composed of repeating units derived from one or more aromatic hydroxycarboxylic acids and their derivatives; (2) polyesters mainly composed of (a) repeating units derived from one or more aromatic hydroxycarboxylic acids and their derivatives, and (b) repeating units derived from one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids and their derivatives; (3) polyesters mainly composed of (a) repeating units derived from one or more aromatic hydroxycarboxylic acids and their derivatives, (b) repeating units derived from one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids and their derivatives, and (c) repeating units derived from at least one or more aromatic diols, alicyclic diols, aliphatic diols and their derivatives; (4) polyesters mainly composed of (a) repeating units derived from one or two or more aromatic hydroxycarboxylic acids and their derivatives, (b) repeating units derived from one or two or more aromatic hydroxyamines, aromatic diamines and their derivatives, and (c) repeating units derived from at least one or two or more aromatic dicarboxylic acids, cycloaliphatic dicarboxylic acids and their derivatives; (5) polyesteramides mainly composed of (a) repeating units derived from one or two or more aromatic hydroxycarboxylic acids and their derivatives, (b) repeating units derived from one or two or more aromatic hydroxyamines, aromatic diamines and their derivatives, (c) repeating units derived from one or two or more aromatic dicarboxylic acids, cycloaliphatic dicarboxylic acids and their derivatives, and (d) repeating units derived from at least one or two or more aromatic diols, cycloaliphatic diols, aliphatic diols and their derivatives, etc. Furthermore, the molecular weight regulator can also be used in combination with the above-mentioned components as required.

Preferred examples of specific compounds constituting the liquid crystal resin (A) applicable to the present invention include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; aromatic diols such as 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, compounds represented by the following general formula (I), and compounds represented by the following general formula (II); aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 4,4'-diphenyl dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and compounds represented by the following general formula (III); aromatic amines such as p-aminophenol and p-phenylenediamine.

(X: a group selected from a self-extending alkyl group (C ₁ to C ₄ ), an alkylene group, -O-, -SO-, -SO ₂ -, -S-, and -CO-)

(Y is a group selected from -(CH ₂ ) _n -(n=1~4) and -O(CH ₂ ) _n O-(n=1~4).)

The liquid crystal resin (A) applicable to the present invention preferably comprises the following structural units (I) to (VI) as essential components, wherein the content of the structural unit (I) is 50 to 70 mol% relative to the entire structural unit, the content of the structural unit (II) is 0.5 mol% or more and less than 4.5 mol% relative to the entire structural unit, the content of the structural unit (III) is 10.25 to 22.25 mol% relative to the entire structural unit, the content of the structural unit (IV) is 0.5 mol% or more and less than 4.5 mol% relative to the entire structural unit, The content of structural unit (V) is 5.75-23.75 mol%, relative to the whole structural unit, the content of structural unit (VI) is 1-7 mol%, relative to the whole structural unit, the total content of structural unit (II) and structural unit (IV) is 1 mol% or more and less than 5 mol%, relative to the whole structural unit, the total content of structural units (I)-(VI) is 100 mol%, relative to the total content of structural unit (V) and structural unit (VI), the molar ratio of structural unit (VI) is 0.04-0.37, and it is a wholly aromatic polyester amide that exhibits optical anisotropy when melted.

[Chemical formula 4]

The (A) liquid crystal resin used in the present invention can be prepared by using the above-mentioned monomer compound (or a mixture of monomers) by a known method using a direct polymerization method or an ester exchange method, usually using a melt polymerization method, a solution polymerization method, a slurry polymerization method, a solid phase polymerization method, etc., or using a combination of two or more of the above methods, wherein the use of a melt polymerization method or a combination of a melt polymerization method and a solid phase polymerization method is preferred. The above-mentioned compound having ester forming ability can be used directly in the polymerization reaction, or can also be modified from a precursor to a derivative having the above-mentioned ester forming ability in the early stage of polymerization. Various catalysts can be used in the polymerization reaction of these materials, and metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanium, lead acetate, sodium acetate, antimony trioxide, tris(2,4-pentanedionato)cobalt(III) and organic compound catalysts such as N-methylimidazole and 4-dimethylaminopyridine can be listed as typical examples. The amount of catalyst used is usually about 0.001~1 mass %, preferably about 0.01~0.2 mass % relative to the total weight of the monomer. If more polymers produced by these polymerization methods are needed, the molecular weight can be increased by solid phase polymerization under reduced pressure or in an inert gas.

The melt viscosity of the liquid crystal resin (A) obtained by the method described above is not particularly limited. Generally, a liquid crystal resin having a melt viscosity of 3 Pa.s to 500 Pa.s at a shear rate of 1000 sec ^-1 at the molding temperature can be used. However, liquid crystal resins with too high a viscosity are not recommended for use because their fluidity is extremely deteriorated. In addition, the above-mentioned (A) liquid crystal resin can also be a mixture of two or more liquid crystal resins.

According to the liquid crystal resin composition of the present invention, the content of the (A) liquid crystal resin in the liquid crystal resin composition is 62.5-72.5% by weight relative to the entire liquid crystal resin composition. When the content of the (A) liquid crystal resin is less than 62.5% by weight relative to the entire liquid crystal resin composition, the fluidity of the liquid crystal resin composition is likely to deteriorate, and there is a concern that the bending strain of a molded product such as a connector obtained from the liquid crystal resin composition may decrease, and therefore this content is not recommended. When the content of (A) liquid crystal resin exceeds 72.5% by mass relative to the total amount of the liquid crystal resin composition, the flexural elastic modulus and the warping deformation suppression effect of the molded products such as connectors obtained from the liquid crystal resin composition are reduced, so this content is not recommended. According to the liquid crystal resin composition of the present invention, the content of (A) liquid crystal resin in the liquid crystal resin composition is preferably 63.5-71.5% by mass, and more preferably 65-70% by mass relative to the total amount of the liquid crystal resin composition.

[(B) Fibrous wollastonite]

(B) The aspect ratio of fibrous wollastonite, that is, the value of average fiber length/average fiber diameter is 8 or more. From the perspective of the flexural elastic modulus and the effect of suppressing warping deformation of molded products such as connectors obtained from the liquid crystal resin composition of the present invention, the aspect ratio is preferably 10 to 25, and more preferably 15 to 20.

The (B) fibrous wollastonite is not particularly limited, and for example, a known fibrous wollastonite can be used. (B) Fibrous wollastonite can be used alone or in combination of two or more types having different aspect ratios, average fiber lengths, average fiber diameters, etc.

(B) The average fiber diameter of the fibrous wollastonite is preferably 3.0 to 50 μm, and more preferably 4.5 to 40 μm. When the average fiber diameter is 3.0 μm or more, it is easy to ensure that the molded products such as connectors obtained from the liquid crystal resin composition of the present invention have sufficient mechanical strength and load deflection temperature. When the average fiber diameter is 50 μm or less, the surface of the molded product is easy to have a better fuzz suppression effect. In addition, in this specification, the fibrous wollastonite is observed using a scanning electron microscope and the fiber diameters of 100 fibrous wollastonites are measured and the average value is obtained as the average fiber diameter.

(B) The average fiber length of the fibrous wollastonite is preferably 30 to 800 μm, more preferably 50 to 600 μm. When the average fiber length is 30 μm or more, it is easy to ensure that the molded product such as a connector obtained from the liquid crystal resin composition of the present invention has sufficient mechanical strength and load deflection temperature. When the average fiber length is 800 μm or less, the surface of the molded product is easy to have a better fuzz suppression effect. In addition, in this manual, 10 stereoscopic microscope images of fibrous wollastonite are captured from a CCD camera to a PC, and by using an image processing method using an image measuring device, the fiber lengths of 100 fibrous wollastonites in each stereoscopic microscope image, i.e., a total of 1,000 fibrous wollastonites, are measured and the average value is obtained as the average fiber length.

According to the liquid crystal resin composition of the present invention, the content of the (B) fibrous wollastonite in the liquid crystal resin composition is 2.5 to 15% by mass relative to the entire liquid crystal resin composition. When the content of the (B) fibrous wollastonite is less than 2.5% by mass relative to the entire liquid crystal resin composition, there is a concern that the warp deformation of the molded product such as a connector obtained from the liquid crystal resin composition, especially the warp deformation after reflow, may increase, and therefore this content is not recommended. When the content of (B) fibrous wollastonite exceeds 15% by mass relative to the entire liquid crystal resin composition, the fluidity of the liquid crystal resin composition tends to deteriorate, and there is a concern that the bending strain of molded products such as connectors obtained from the liquid crystal resin composition may decrease, so this content is not recommended. In the present invention, the content of (B) fibrous wollastonite in the liquid crystal resin composition is preferably 3-13% by mass, and more preferably 5-10% by mass relative to the entire liquid crystal resin composition.

[(C) Mica]

The liquid crystal resin composition according to the present invention includes mica. By including mica in the liquid crystal resin composition according to the present invention, a molded product having a sufficient flexural elastic modulus and suppressed warping deformation can be obtained. Mica can be used alone or in combination of two or more.

The content of mica is 17.5-30% by mass relative to the whole liquid crystal resin composition. When the content of mica is less than 17.5% by mass relative to the whole liquid crystal resin composition, the bending elastic modulus of the molded product obtained from the liquid crystal resin composition cannot be sufficiently improved and the warp cannot be sufficiently suppressed, so this content is not recommended. When the content of mica exceeds 30% by mass relative to the whole liquid crystal resin composition, the fluidity of the liquid crystal resin composition deteriorates and the liquid crystal resin composition may become difficult to mold, so this content is not recommended. The content of mica in the liquid crystal resin composition is preferably 18.5-27.5% by mass relative to the whole liquid crystal resin composition, and more preferably 20-25% by mass.

[Mica]

Mica is a powder of silicate minerals 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. Among them, muscovite is preferred in view of its good color tone and low price.

Furthermore, in the production of mica, as methods for crushing minerals, wet crushing and dry crushing are known. The so-called wet crushing method refers to a method in which raw mica is coarsely crushed with a dry crusher, water is added, and the raw mica is mainly crushed by wet crushing in a slurry state, and then dehydrated and dried. Compared with the wet crushing method, the dry crushing method is a common method with a lower cost, but it is easier to crush the mineral into thin and fine particles when using the wet crushing method. Since mica with a better average particle size and thickness described later can be obtained, it is preferred to use thin and fine crushed materials in the present invention. Therefore, in the present invention, it is preferred to use mica produced by the wet crushing method.

Furthermore, in the wet pulverization method, since it is necessary to disperse the material to be pulverized in water, a coagulant and/or a sedimentation aid is usually added to the material to be pulverized to improve the dispersion efficiency of the material to be pulverized. As the coagulant and sedimentation aid used in the present invention, there can be listed polyaluminum chloride, aluminum sulfate, ferrous sulfate, ferric sulfate, hydrochloric alum, polyferric sulfate, polyferric chloride, iron-silicon dioxide inorganic polymer coagulant, ferric chloride-silicon dioxide inorganic polymer coagulant, slaked lime (Ca(OH) ₂ ), caustic soda (NaOH), pure alkali (Na ₂ CO ₃ ) (soda ash), etc. The pH value of these coagulation sedimentation agents and sedimentation aids is alkaline or acidic. The mica used in the present invention is preferably mica that is not treated with coagulation sedimentation agents and/or sedimentation aids during wet pulverization. When mica that has not been treated with coagulation sedimentation agents and/or sedimentation aids is used, the polymer in the liquid crystal resin composition is almost not decomposed, and it is unlikely that a large amount of gas will be generated or the molecular weight of the polymer will be reduced, so it is easy to maintain the performance of the obtained molded product such as a connector more well.

The mica that can be used in the present invention preferably has an average particle size of 10 to 100 μm as measured by micro track laser diffraction, and particularly preferably has an average particle size of 20 to 80 μm. The average particle size of mica is preferably 10 μm or more because it is easy to fully obtain the improvement effect on the rigidity of the molded product. The average particle size of mica is preferably 100 μm or less because it is easy to fully improve the rigidity of the molded product and also easy to have sufficient welding strength. Moreover, when the average particle size of mica is 100 μm or less, it is easy to ensure sufficient fluidity when molding the connector of the present invention.

The thickness of mica that can be used in the present invention is preferably 0.01~1μm, and particularly preferably 0.03~0.3μm, as measured by electron microscope observation. The thickness of mica is preferably 0.01μm or more because mica is almost not broken during the melt processing of the liquid crystal resin composition, so it is easy to improve the rigidity of the molded product. The thickness of mica is preferably 1μm or less because it is easy to fully obtain the improvement effect on the rigidity of the molded product.

Mica that can be used in the present invention can also be surface treated with a silane coupling agent and/or granulated with an adhesive to form particles.

In the liquid crystal resin composition according to the present invention, the total content of (B) fibrous wollastonite and (C) mica is 27.5-37.5% by weight relative to the entire liquid crystal resin composition. When the above content is less than 27.5% by weight relative to the entire liquid crystal resin composition, the bending elastic modulus and the effect of suppressing warping deformation of the molded products such as connectors obtained from the liquid crystal resin composition are reduced, so this content is not recommended. When the above content exceeds 37.5% by weight relative to the entire liquid crystal resin composition, the fluidity of the liquid crystal resin composition is likely to deteriorate, and there is a concern that the bending strain of the molded products such as connectors obtained from the liquid crystal resin composition will decrease, so this content is not recommended. The above content is preferably 28.0-36.5% by mass relative to the entire liquid crystal resin composition, and more preferably 28.5-35% by mass.

[Other ingredients]

According to the liquid crystal resin composition of the present invention, other components can be appropriately added according to the required properties within the scope that does not damage the effect of the present invention, such as other polymers, other fillers, known substances generally added to synthetic resins, that is, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, flame retardants, colorants such as dyes and pigments, lubricants, stripping agents, crystallization promoters, crystal nucleating agents, etc. The above other components can be used alone or in combination of two or more.

The so-called other fillers refer to fillers other than fibrous wollastonite, mica, and carbon black having an aspect ratio of 8 or more. For example, fibrous fillers other than fibrous wollastonite having an aspect ratio of 8 or more (for example, fibrous wollastonite with an aspect ratio of less than 8, milled fiber), and plate-shaped fillers other than mica (for example, talc) can be listed. However, from the perspective of improving the mechanical strength of the molded product and suppressing warping deformation, the liquid crystal resin composition according to the present invention preferably does not contain fibrous wollastonite, milled fiber, and talc with an aspect ratio of less than 8.

The method for producing the liquid crystal resin composition according to the present invention is not particularly limited as long as the components in the liquid crystal resin composition can be uniformly mixed, and can be appropriately selected from the conventionally known methods for producing resin compositions. For example, a method can be cited in which the components are melt-kneaded and extruded using a single-screw or twin-screw extruder, and then the obtained liquid crystal resin composition is processed into a desired form such as powder, flakes, or pellets.

Since the liquid crystal resin composition according to the present invention has excellent fluidity, the minimum filling pressure during molding will hardly become too high, so the connector can be well molded, especially small and complex-shaped parts such as thin narrow-pitched connectors. The degree of fluidity depends on the minimum filling pressure of the connector. That is, the minimum injection filling pressure at which a good molded product can be obtained during injection molding of the FPC connector shown in FIG. 1 is set as the minimum filling pressure. The lower the minimum filling pressure, the better the fluidity is evaluated.

The melt viscosity of the liquid crystal resin composition measured according to ISO 11443 at a high temperature 10-30°C higher than the melting point of the liquid crystal resin and a shear rate of 1000/s is preferably 1×10 ⁵ Pa. s or less, and more preferably 5 Pa. s or more and 1×10 ² Pa. s or less. When the above melt viscosity is 1×10 ⁵ Pa. s or less, it is easy to ensure the fluidity of the liquid crystal resin composition when molding the connector, especially the thin and narrow-pitched connector, and the filling pressure will hardly become too large.

(Connector)

The connector according to the present invention can be obtained by molding the liquid crystal resin composition according to the present invention. The connector of the present invention is not particularly limited, and for example, a connector with a total length of less than 30 mm and a height of less than 5 mm can be listed. The connector with a total length of less than 30 mm and a height of less than 5 mm is not particularly limited, and for example, a thinned narrow-pitch connector, a coaxial connector, a micro SIM connector, a micro SD connector, etc. can be listed. Among them, the thinned narrow-pitch connector is very suitable. There is no particular limitation on thin and narrow-pitch connectors, such as substrate-to-substrate connectors (also called "BtoB connectors"), flexible printed circuit board connectors (used to connect flexible printed circuit boards (FPCs) and flexible flat cables (FFCs), also called "FPC connectors"), etc. Among them, thin and narrow-pitch connectors with a distance between the intercepts of less than 0.5mm, a total length of the product of more than 3.5mm and less than 30mm, and a height of less than 1.5mm, and substrate-to-substrate connectors or flexible printed circuit board connectors are very suitable.

The molding method used to obtain the connector of the present invention is not particularly limited, but in order to prevent the obtained connector from being deformed, it is better to select molding conditions that will not cause residual internal stress. In order to reduce the filling pressure and reduce the residual internal stress of the obtained connector, the cylinder temperature of the molding machine is preferably a temperature above the melting point of the liquid crystal resin.

Furthermore, the mold temperature is preferably 70~100℃. When the mold temperature is low, the liquid crystal resin composition filled in the mold may flow poorly, so it is not recommended. When the mold temperature is high, burrs and other problems may occur, so it is not recommended. Regarding the injection speed, it is best to inject at more than 150mm/second. When the injection speed is low, it is possible to obtain only unfilled molded products, and even if a fully filled molded product is obtained, it will become a molded product with high filling pressure and large residual internal stress, and it is possible to obtain only a connector with poor flatness.

The connector of the present invention suppresses warping deformation. The degree of connector warping is determined as described below. That is, the height of the FPC connector shown in FIG. 1 is measured at multiple positions indicated by black dots in FIG. 2, and the difference between the maximum height and the minimum height of the least square method is regarded as warping. The connector of the present invention suppresses the change of warping before and after IR reflow.

Furthermore, the connector of the present invention has excellent heat resistance, such as heat resistance evaluated by high temperature stiffness. High temperature stiffness is evaluated by measuring the deflection temperature under load according to ISO 75-1 and ISO 75-2.

The connector of the present invention has excellent mechanical strength. The mechanical strength is evaluated by measuring the bending strength, bending strain, and bending elastic modulus according to the bending test of ASTM D790.

[Implementation example]

The present invention is described in detail below by using an embodiment, but the present invention is not limited thereto.

<Implementation Examples 1~5, Comparative Examples 1~7>

In the following examples and comparative examples, liquid crystal resins LCP1 and LCP2 were produced as described below. At this time, the melting point and melt viscosity of the pellets were measured under the following conditions.

[Measurement of melting point]

Using a DSC manufactured by TA Instruments, after observing the endothermic peak temperature (Tm1) observed when measuring the liquid crystal resin under the condition of heating from room temperature at 20°C/min, it was kept at a temperature of (Tm1+40)°C for 2 minutes, cooled to room temperature under the condition of heating at 20°C/min, and then the endothermic peak temperature observed when measuring under the condition of heating at 20°C/min was measured again.

[Measurement of melt viscosity]

The melt viscosity of the liquid crystal resin was measured in accordance with ISO11443 using a Capillograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd. at a high temperature 10~30℃ higher than the melting point of the liquid crystal resin, using an orifice with an inner diameter of 1mm and a length of 20mm, and a shear rate of 1000/sec. The measurement temperature for LCP1 was 360℃, and the measurement temperature for LCP2 was 380℃.

(Manufacturing method of LCP1)

Add the following raw monomers, fatty acid metal salt catalyst, acylation agent into a polymerization vessel equipped with a stirrer, reflux tower, monomer inlet, nitrogen inlet, and decompression/outflow pipeline, and perform nitrogen substitution.

(I) 4-Hydroxybenzoic acid: 1385 g (60 mol%) (HBA)

(II) 6-Hydroxy-2-naphthoic acid: 88 g (2.8 mol%) (HNA)

(III) Terephthalic acid: 504 g (18.15 mol%) (TA)

(IV) Isophthalic acid: 19 g (0.7 mol%) (IA)

(V) 4,4'-dihydroxybiphenyl: 415 g (13.35 mol%) (BP)

(VI) N-acetyl-p-aminophenol: 126 g (5 mol%) (APAP)

Potassium acetate catalyst: 120mg

Acetic anhydride: 1662g

After adding the raw materials to the polymerization vessel, the temperature of the reaction system is raised to 140°C, and the reaction is carried out at 140°C for 1 hour. After that, the temperature is further raised to 360°C within 5.5 hours, and then the pressure is reduced to 10Torr (i.e., 1330Pa) within 20 minutes to distill out acetic acid, excess acetic anhydride, and other low-boiling components while melt polymerization is carried out. After the stirring torque reaches a predetermined value, nitrogen is introduced to change from a depressurized state to a pressurized state through normal pressure, and the polymer is discharged from the bottom of the polymerization vessel and changes from a linear state to a granular state to complete granulation. The melting point of the obtained pellets is 345°C and the melt viscosity is 10Pa. s.

(LCP2 manufacturing method)

Add the following raw monomers, fatty acid metal salt catalyst, acylation agent into a polymerization vessel equipped with a stirrer, reflux tower, monomer inlet, nitrogen inlet, and decompression/outflow pipeline, and perform nitrogen substitution.

(I) 4-Hydroxybenzoic acid: 1040 g (48 mol%) (HBA)

(II) 6-Hydroxy-2-naphthoic acid: 89 g (3 mol%) (HNA)

(III) Terephthalic acid: 547 g (21 mol%) (TA)

(IV) Isophthalic acid: 91 g (3.5 mol%) (IA)

(V) 4,4'-dihydroxybiphenyl: 716 g (24.5 mol%) (BP)

Potassium acetate catalyst: 110mg

Acetic anhydride: 1644g

After adding the raw materials to the polymerization vessel, the temperature of the reaction system is raised to 140°C, and the reaction is carried out at 140°C for 1 hour. After that, the temperature is further raised to 360°C within 5.5 hours, and then the pressure is reduced to 5 Torr (i.e., 667 Pa) within 20 minutes, and melt polymerization is carried out while distilling out acetic acid, excess acetic anhydride, and other low-boiling components. After the stirring torque reaches a predetermined value, nitrogen is introduced to change from a depressurized state to a pressurized state through normal pressure, and the polymer is discharged from the bottom of the polymerization vessel and changes from a linear shape to a granular shape to complete granulation. The melting point of the obtained pellets is 355°C and the melt viscosity is 10Pa. s.

(Ingredients other than liquid crystal resin)

‧Fiber fillers

Wollastonite 1: NYGLOS 8 (manufactured by NYCO Materials, with an aspect ratio of 17, an average fiber length of 136μm, and an average fiber diameter of 8μm)

Wollastonite 2: NYAD 325 (manufactured by NYCO Materials, with an aspect ratio of 5, an average fiber length of 50μm, and an average fiber diameter of 5μm)

Milled fiber: PF70E001 manufactured by Nitto Bosho Co., Ltd., fiber diameter is 10μm, average fiber length is 70μm (manufacturer's nominal value)

‧Plate filler

Mica; AB-25S manufactured by Yamaguchi Mica Industry Co., Ltd., average particle size 25μm

Talc; Crown Talc PP manufactured by Matsumura Industrial Co., Ltd., average particle size 10μm

Using a twin-screw extruder, the various liquid crystal resins obtained above and the components other than the liquid crystal resins are mixed to obtain a liquid crystal resin composition. The blending amount of each component is shown in Table 1 and Table 2. In addition, in the following tables, "%" for the blending amount represents mass %. Furthermore, the extrusion conditions for obtaining the liquid crystal resin composition are as follows.

[Extrusion conditions]

[Implementation Examples 1 to 4, Comparative Examples 1 to 7]

The temperature of the cylinder located at the main feed port is set to 250°C, and the temperature of all other cylinders is set to 360°C. All liquid crystal resins are supplied from the main feed port. In addition, fillers are supplied from the side feed port.

[Implementation Example 5]

The temperature of the cylinder located at the main feed port is set to 250°C, and the temperature of all other cylinders is set to 370°C. All liquid crystal resins are supplied from the main feed port. In addition, fillers are supplied from the side feed port.

(Measurement of melt viscosity of liquid crystal resin composition)

The melt viscosity of the liquid crystal resin was measured in accordance with ISO11443 using a Capillograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd. at a high temperature 10 to 30°C higher than the melting point of the liquid crystal resin, using a nozzle with an inner diameter of 1mm and a length of 20mm, and a shear rate of 1000/sec. In addition, the measurement temperature of the liquid crystal resin composition using LCP1 was 360°C, and the measurement temperature of the liquid crystal resin composition using LCP2 was 380°C. The results are shown in Tables 1 and 2.

Based on the following method, the physical properties of connectors of molded products including liquid crystal resin compositions were measured. The various evaluation results are shown in Tables 1 and 2.

(Load deflection temperature)

Under the following molding conditions, the liquid crystal resin composition was injection molded to obtain a molded product, and the load deflection temperature was measured according to ISO 75-1 and ISO 75-2.

[Molding conditions]

Molding machine: SE100DU manufactured by Sumitomo Heavy Industries

Cylinder temperature:

360℃ (Examples 1 to 4, Comparative Examples 1 to 7)

370℃ (Example 5)

Mold temperature: 80℃

Injection speed: 33mm/sec

(Bend test)

Under the following molding conditions, the liquid crystal resin composition was injection molded to obtain a molded product with a thickness of 0.8 mm, and the flexural strength, flexural strain, and flexural elastic modulus were measured according to ASTM D790.

[Molding conditions]

Molding machine: SE100DU manufactured by Sumitomo Heavy Industries

Cylinder temperature:

360℃ (Examples 1 to 4, Comparative Examples 1 to 7)

370℃ (Example 5)

Mold temperature: 80℃

Injection speed: 33mm/sec

(Bending of FPC connector)

Under the following molding conditions, the liquid crystal resin composition was injection molded (gate: tunnel gate, gate size: φ0.4mm) to obtain an FPC connector with an overall size of 17.6mm×4.00mm×1.16mm, a distance between intercepts of 0.5mm, a number of pinholes of 30×2 pins, and a minimum wall thickness of 0.12mm, as shown in Figure 1.

[Molding conditions]

Molding machine: SE30DUZ manufactured by Sumitomo Heavy Industries

Cylinder temperature (displayed as the temperature from the nozzle side):

360℃-360℃-350℃-340℃ (Examples 1~4, Comparative Examples 1~7)

370℃-370℃-360℃-350℃ (Example 5)

Mold temperature: 80℃

Injection speed: 200mm/sec

Holding pressure: 50MPa

Holding time: 0.5 seconds

Cooldown time: 10 seconds

Screw speed: 120rpm

Screw back pressure: 1.2MPa

The obtained connector was placed on a horizontal table and the height of the connector was measured using the Quick Vision 404 PROCNC image measuring machine manufactured by Mitutoyo Corporation. At this time, the height was measured at multiple positions indicated by black dots in Figure 2, and the difference between the maximum height and the minimum height of the minimum square method was regarded as the warp of the FPC connector. In addition, the warp was measured before and after IR reflow under the following conditions.

[IR reflow conditions]

Measuring instrument: Large desktop reflow equipment RF-300 manufactured by Japan Pulse Technology Research Institute (using far infrared heater)

Sample supply speed: 140mm/sec

Reflux furnace transit time: 5 minutes

Temperature condition of preheating zone: 150℃

Temperature condition of reflow zone: 190℃

Peak temperature: 251℃

(Minimum filling pressure of FPC connector)

The minimum injection filling pressure that can produce a good molded product during injection molding of the FPC connector in Figure 1 was measured and used as the minimum filling pressure.

As shown in Table 1 and Table 2, in the embodiment, the load buckling temperature is above 245°C, the bending strain is above 2.0%, the bending elastic modulus is above 14000MPa, the warp of the FPC connector before reflow is less than 0.030mm, the warp of the FPC connector after reflow is less than 0.090mm, and the minimum filling pressure of the FPC connector is less than 75MPa. Therefore, it is confirmed that the liquid crystal resin composition according to the present invention has excellent fluidity, and the connector of the molded product including the liquid crystal resin composition has excellent heat resistance and mechanical strength, and the warp deformation is also suppressed.

Claims (5)

A liquid crystal resin composition comprising (A) a liquid crystal resin, (B) fibrous wollastonite and (C) mica, wherein the aspect ratio of the fibrous wollastonite (B) is greater than 8, and the content of the liquid crystal resin (A) is 62.5-72.5% by weight, the content of the fibrous wollastonite (B) is 2.5-15% by weight, and the content of the mica (C) is 1.2-1.3%. The content of the above-mentioned (B) fibrous wollastonite and the above-mentioned (C) mica is 17.5-30% by mass, and the total content of the above-mentioned (B) fibrous wollastonite and the above-mentioned (C) mica is 27.5-37.5% by mass, wherein the (A) liquid crystal resin is composed of the following structural units (I) to (VI) as essential components: relative to the overall structural unit, the content of the structural unit (I) is 50-70 mol%, relative to the overall structural unit, the content of the structural unit (II) is 0.5 mol% or more The content of the structural unit (III) is 10.25-22.25 mol% relative to the whole structural unit, the content of the structural unit (IV) is 0.5 mol% or more and less than 4.5 mol% relative to the whole structural unit, the content of the structural unit (V) is 5.75-23.75 mol% relative to the whole structural unit, and the content of the structural unit (VI) is 1-7 mol% relative to the whole structural unit. %, relative to the whole structural unit, the total content of the structural unit (II) and the structural unit (IV) is greater than 1 mol% and less than 5 mol%, relative to the whole structural unit, the total content of the structural units (I) to (VI) is 100 mol%, and relative to the total content of the structural unit (V) and the structural unit (VI), the molar ratio of the structural unit (VI) is 0.04-0.37, and it is a wholly aromatic polyester amide that exhibits optical anisotropy when melted,

The liquid crystal resin composition described in Item 1 of the patent application scope is used for connectors with a total length of less than 30 mm and a height of less than 5 mm. A connector, comprising a molded product of a liquid crystal resin composition as described in item 1 or 2 of the patent application, and the total length of the product is less than 30 mm and the height of the product is less than 5 mm. The connector described in item 3 of the patent application is a thinned narrow-pitch connector. The connector described in item 3 or 4 of the patent application scope is a thinned narrow pitch connector of a substrate-to-substrate connector or a flexible brush circuit board connector, wherein the pitch distance is less than 0.5 mm, the total length of the product is more than 3.5 mm and less than 30 mm, and the product height is less than 1.5 mm.

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