KR20240058096A - Absence of electromagnetic shield - Google Patents

Abstract

An electromagnetic wave shield member molded from a liquid crystalline resin composition excellent in molding processability and having excellent electromagnetic wave shielding properties is provided. The electromagnetic wave shield member according to the present invention is made of a molded body of a liquid crystalline resin composition containing (A) a liquid crystalline resin, (B) a fibrous conductive filler, and (C) a granular conductive filler, and the (B) fibrous conductive filler The total content of the filler and the granular conductive filler (C) is 15 to 60% by mass, and the mass ratio of the content of the fibrous conductive filler (B) to the content of the granular conductive filler (C) is 0.30 to 22.0. and the electromagnetic wave shielding member has an electromagnetic wave shielding property of 35 dB or more at a frequency of 100 MHz, as measured based on the KEC method.

Description

Absence of electromagnetic shield

The present invention relates to electromagnetic wave shield members.

Liquid crystalline resin, represented by liquid crystalline polyester resin, is widely used as a high-performance engineering plastic because it has a good balance of excellent mechanical strength, heat resistance, chemical resistance, and electrical properties, and also has excellent dimensional stability. In addition, for example, Patent Document 1 discloses a liquid crystal polyester resin composition with excellent moldability, and the molded article obtained by molding the liquid crystal polyester resin composition has excellent electromagnetic wave shielding properties and electrical insulation properties, and can be used in electronic devices. Also disclosed are useful members related to .

Patent Laid-open No. 2008-1110110

Recently, with the transition from LTE to 5G, significant improvements in signal transmission speed and signal accuracy are needed in many products such as connectors, transmission boards, and antennas. While conductive materials such as connector materials are being developed in relation to high-speed communications, the importance of thermoplastic conductive materials that can be given complex shapes as a countermeasure against noise by forming electromagnetic wave shields is coming into focus.

Candidates for the above conductive materials include liquid crystalline resin compositions. However, according to examination by the present inventors, the electromagnetic wave shielding properties of conventional liquid crystalline resin compositions are not sufficient, and furthermore, since the melt viscosity is high, the molding processability is not sufficient. The present invention was made to solve the above problems, and its purpose is to provide an electromagnetic wave shield member that is molded from a liquid crystalline resin composition excellent in molding processability and has excellent electromagnetic wave shielding properties.

The present inventors have conducted extensive research to solve the above problems. As a result, it is made of a molded body of a liquid crystalline resin composition containing a liquid crystalline resin, a fibrous conductive filler, and a granular conductive filler, the total content of the fibrous conductive filler and the granular conductive filler is within a predetermined range, and the granular conductive filler is formed. It was discovered that the above problem could be solved by using an electromagnetic wave shielding member in which the mass ratio of the content of the fibrous conductive filler to the content of the filler was within a predetermined range and the electromagnetic wave shielding property was within a predetermined range, and the present invention was completed. It came down to this. More specifically, the present invention provides the following.

(1) An electromagnetic wave shield member made of a molded body of a liquid crystalline resin composition containing (A) a liquid crystalline resin, (B) a fibrous conductive filler, and (C) a granular conductive filler,

The total content of the fibrous conductive filler (B) and the granular conductive filler (C) is 15 to 60% by mass,

The mass ratio of the content of the fibrous conductive filler (B) to the content of the granular conductive filler (C) is 0.30 to 22.0,

The electromagnetic wave shield member is an electromagnetic wave shield member having an electromagnetic wave shielding property of 35 dB or more at a frequency of 100 MHz, measured in accordance with the KEC method.

(2) The total content of the fibrous conductive filler (B) and the granular conductive filler (C) is 20 to 50% by mass,

The electromagnetic wave shield member according to (1), wherein the mass ratio of the content of the fibrous conductive filler (B) to the content of the granular conductive filler (C) is 0.50 to 20.0.

(3) The fibrous conductive filler (B) is carbon fiber,

The electromagnetic wave shield member according to (1) or (2), wherein the granular conductive filler (C) is carbon black.

(4) The electromagnetic wave shield member according to any one of (1) to (3), wherein the liquid crystalline resin composition further contains (D) a non-conductive filler.

(5) The electromagnetic wave shield member according to any one of (1) to (4), wherein the content of the non-conductive filler (D) is 2 to 8% by mass.

(6) The non-conductive filler (D) is selected from the group consisting of talc, mica, glass flakes, silica, glass beads, glass balloons, potassium titanate whiskers, calcium silicate whiskers, milled glass fibers, and glass fibers. One or more types of electromagnetic wave shield members according to (4) or (5).

(7) The electromagnetic wave shield member according to any one of (4) to (6), wherein the non-conductive filler (D) is at least one selected from the group consisting of talc, mica, silica, and glass fiber.

According to the present invention, it is possible to provide an electromagnetic wave shield member that is molded from a liquid crystalline resin composition excellent in molding processability and has excellent electromagnetic wave shielding properties.

Hereinafter, embodiments of the present invention will be described. Additionally, the present invention is not limited to the following embodiments.

<Absence of electromagnetic shield>

The electromagnetic wave shield member of the present invention is made of a molded body of a liquid crystalline resin composition containing (A) a liquid crystalline resin, (B) a fibrous conductive filler, and (C) a granular conductive filler, and the (B) fibrous conductive filler The total content of the filler and the granular conductive filler (C) is 15 to 60% by mass, and the mass ratio of the content of the fibrous conductive filler (B) to the content of the granular conductive filler (C) is 0.30 to 22.0. And the electromagnetic shielding property at a frequency of 100 MHz, measured in accordance with the KEC method, is 35 dB or more. The electromagnetic wave shield member according to the present invention is molded from a liquid crystalline resin composition with excellent molding processability, and also has excellent electromagnetic wave shielding properties.

The electromagnetic shielding member according to the present invention has an electromagnetic shielding property of 35 dB or more at a frequency of 100 MHz, measured based on the KEC method, and is excellent in electromagnetic shielding properties. The electromagnetic shielding property is preferably 37 dB or more, and more preferably 38 dB or more.

The electromagnetic wave shield member of the present invention can be suitably used in applications requiring excellent electromagnetic wave shielding properties, and specifically, various cases, gear cases, LED packages and LED lamp-related parts, connectors, relay cases, switches, baricon cases, optical Pickup lens holder, optical pickup slide base, lamp reflector, various terminal boards, transformers, printed wiring boards, liquid crystal panel frames, power modules and their housings, plastic magnets, semiconductors, liquid crystal display components, lamp covers such as projectors, FDD carriage, FDD chassis. , electrical and electronic components such as HDD components such as actuators and chassis, and computer-related components; VTR parts, television parts, iron parts, hair dryer parts, rice cooker parts, microwave oven parts, audio parts, audio equipment parts (e.g. audio, laser disk (registered trademark), compact disk, digital video disk, etc.), lighting Home and office electrical product parts such as parts, refrigerator parts, air conditioner parts, etc.; Optics represented by office computer-related parts, telephone-related parts, facsimile-related parts, printer/copier-related parts such as around the print head and transfer roll, cleaning jigs, motor parts, microscope parts, binocular parts, camera parts, watch parts, etc. Parts related to devices and precision machinery; AC terminal, AC connector, IC regulator, potentiometer base for light dimmer, motor core sealing material, insulator member, power seat gear housing, thermostat base for air conditioner, air conditioner panel switch board, horn terminal, electrical component insulation plate, lamp housing, ignition Automobile and vehicle-related parts such as device cases, air pressure sensors, fuse connectors, and vehicle speed sensors; It is particularly suitable for information and communication-related parts such as personal computer housings, mobile phone housings, mobile phone base station antenna cases, chip antennas in the information and communication field, wireless LAN antennas, ETC (electronic toll collection system) antennas, and satellite communication antennas. You can use it.

[(A) Liquid crystalline resin]

The (A) liquid crystalline resin used in the present invention refers to a melt-processable polymer that has the property of forming an optically anisotropic molten phase. The properties of the anisotropic melt phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, confirmation of the anisotropic molten phase can be performed by using a Leitz polarizing microscope and observing a molten sample placed on a Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere. When the liquid crystalline polymer applicable to the present invention is examined between orthogonal polarizers, polarized light usually transmits even if it is in a melted and suspended state, and it exhibits optical anisotropy.

The type of liquid crystalline resin (A) as described above is not particularly limited, and is preferably aromatic polyester and/or aromatic polyesteramide. Additionally, polyesters partially containing aromatic polyester and/or aromatic polyesteramide in the same molecular chain are also within the range. (A) The liquid crystalline resin, when dissolved in pentafluorophenol at a concentration of 0.1 mass% at 60°C, is preferably at least about 2.0 dl/g, more preferably 2.0 to 10.0 dl/g. Those having a viscosity (I.V.) are preferably used.

The aromatic polyester or aromatic polyesteramide as the (A) liquid crystalline resin applicable to the present invention is particularly preferably derived from at least one selected from the group consisting of aromatic hydroxycarboxylic acids and derivatives thereof. It is an aromatic polyester or aromatic polyesteramide that has structural units as constituents.

More specifically

(1) Polyester mainly composed of structural units derived from at least one type selected from the group consisting of aromatic hydroxycarboxylic acids and their derivatives;

(2) structural units mainly derived from (a) at least one selected from the group consisting of aromatic hydroxycarboxylic acids and their derivatives, and (b) aromatic dicarboxylic acids, alicyclic dicarboxylic acids and their Polyester consisting of a structural unit derived from at least one type selected from the group consisting of derivatives;

(3) structural units mainly derived from (a) at least one selected from the group consisting of aromatic hydroxycarboxylic acids and derivatives thereof, and (b) aromatic dicarboxylic acids, cycloaliphatic dicarboxylic acids and their a structural unit derived from at least one type selected from the group consisting of derivatives, and (c) a structural unit derived from at least one type selected from the group consisting of aromatic diols, alicyclic diols, aliphatic diols, and derivatives thereof, Made of polyester;

(4) structural units mainly derived from (a) at least one member selected from the group consisting of aromatic hydroxycarboxylic acids and their derivatives, and (b) from the group consisting of aromatic hydroxyamines, aromatic diamines and derivatives thereof. A polyester consisting of a structural unit derived from at least one selected type, and (c) a structural unit derived from at least one type selected from the group consisting of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and derivatives thereof. amides;

(5) structural units mainly derived from (a) at least one member selected from the group consisting of aromatic hydroxycarboxylic acids and their derivatives, and (b) from the group consisting of aromatic hydroxyamine, aromatic diamine and their derivatives. a structural unit derived from at least one type selected, (c) a structural unit derived from at least one type selected from the group consisting of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof, and (d) and polyesteramides composed of structural units derived from at least one type selected from the group consisting of aromatic diols, alicyclic diols, aliphatic diols, and derivatives thereof. In addition, a molecular weight regulator may be used in combination with the above components as needed.

Preferred examples of specific compounds constituting the liquid crystalline resin (A) applicable to the present invention include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid; 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, hydroquinone, resorcin, a compound represented by the general formula (I) below, and the general formula below: Aromatic diols such as compounds represented by (II); 1,4-phenylenedicarboxylic acid, 1,3-phenylenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and the following general formula (III ) Aromatic dicarboxylic acids such as compounds represented by ); Aromatic amines such as p-aminophenol, p-phenylenediamine, and N-acetyl-p-aminophenol can be mentioned.

(X: A group selected from alkylene (C ₁ to C ₄ ), alkylidene, -O-, -SO-, -SO ₂ -, -S- and -CO-.)

(Y:-(CH ₂ ) _n -(n=1~4) and -O(CH ₂ ) _n O-(n=1~4).)

Preparation of the liquid crystalline resin (A) used in the present invention can be performed by a known method using a direct polymerization method or transesterification method from the above monomer compound (or a mixture of monomers), usually by melt polymerization method or solution. A polymerization method, a slurry polymerization method, a solid-state polymerization method, etc., or a combination of two or more types thereof are used, and a melt polymerization method or a combination of a melt polymerization method and a solid-state polymerization method is preferably used. The above compounds having the ability to form esters may be used in polymerization as is, or may be modified from precursors to derivatives having the ability to form esters in the previous stage of polymerization. During these polymerizations, various catalysts can be used. Representative examples include potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, and tris(2,4-pentanedionato). ) Metal salt catalysts such as cobalt (III), and organic compound catalysts such as 1-methylimidazole and 4-dimethylaminopyridine. The amount of catalyst used is generally about 0.001 to 1% by mass, especially about 0.01 to 0.2% by mass, based on the total mass of monomers. The molecular weight of polymers produced by these polymerization methods can be further increased, if necessary, by solid-phase polymerization by heating under reduced pressure or in an inert gas.

The melt viscosity of the liquid crystalline resin (A) obtained by the above method is not particularly limited. In general, those with a melt viscosity at the molding temperature of 3 Pa·s or more and 500 Pa·s or less at a shear rate of 1000 sec ^-1 can be used. However, having a viscosity that is too high in itself is undesirable because the fluidity deteriorates significantly. Additionally, the liquid crystalline resin (A) may be a mixture of two or more types of liquid crystalline resin.

In the liquid crystalline resin composition of the present invention, the content of (A) liquid crystalline resin is preferably 40 to 85% by mass, more preferably 50 to 80% by mass, and even more preferably 60.5 to 79.5% by mass. %am. (A) If the content of component is within the above range, it is preferable in terms of fluidity, heat resistance, etc.

[(B) Fibrous conductive filler]

The liquid crystalline resin composition according to the present invention includes a fibrous conductive filler. Fibrous conductive fillers can be used individually or in combination of two or more types.

(B) The average fiber length of the fibrous conductive filler is not particularly limited, and from the viewpoint of conductivity, for example, it may be 50 μm or more and 10 mm or less, 80 μm or more and 8 mm or less, or 100 μm or more and 7 mm or less. good night. In addition, in this specification, (B) the average fiber length of the fibrous conductive filler is obtained by inserting 10 stereoscopic microscope images of the fibrous conductive filler into a PC from a CCD camera and processing the image using an image measuring device, followed by 1 stereoscopic microscope image. The average of the fiber length measurements for each 100 fibrous conductive fillers, that is, a total of 1000 fibrous conductive fillers, is adopted. The average fiber length of the (B) fibrous conductive filler in the liquid crystalline resin composition is measured by applying the above method to the remaining fibrous conductive filler after incinerating the liquid crystalline resin composition by heating at 500 ° C. for 4 hours.

(B) The fiber diameter of the fibrous conductive filler is not particularly limited, and may be, for example, 0.2 to 15 μm, 0.25 to 13 μm, or 0.3 to 11 μm from the viewpoint of conductivity. In addition, in this specification, as the fiber diameter of the (B) fibrous conductive filler, the fibrous conductive filler is observed with a scanning electron microscope, and the average of the fiber diameters of 30 fibrous conductive fillers is measured. The fiber diameter of the fibrous conductive filler (B) in the liquid crystalline resin composition is measured by applying the above method to the fibrous conductive filler remaining after incinerating the liquid crystalline resin composition by heating at 500°C for 4 hours.

(B) Examples of the fibrous conductive filler include carbon fiber; Conductive fibers such as metal fibers; Examples include inorganic fibrous materials coated with metals such as nickel and copper to impart conductivity, and carbon fiber is preferred from the viewpoint of conductivity.

Examples of carbon fiber include PAN-based carbon fiber made from polyacrylonitrile as a raw material, and pitch-based carbon fiber made from pitch as a raw material.

Examples of metal fibers include fibers made of mild steel, stainless steel, steel and its alloys, copper, brass, aluminum and its alloys, titanium, lead, etc. These metal fibers can also be coated with other metals to provide further conductivity if necessary due to their conductivity.

Examples of the inorganic fibrous materials include glass fiber, milled glass fiber, asbestos fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate whisker, and calcium silicate whisker (fibrous wollastonite). etc. can be mentioned.

[(C) Granular conductive filler]

The liquid crystalline resin composition according to the present invention includes a granular conductive filler. Granular conductive fillers can be used individually or in combination of two or more types.

(C) The median diameter of the granular conductive filler is not particularly limited, and from the viewpoint of conductivity, for example, it may be 10 nm or more and 50 μm or less, 15 nm or more and 20 μm or less, or 18 nm or more and 10 μm or less. good night. In addition, in this specification, the median diameter refers to the median value on a volume basis measured by a laser diffraction/scattering particle size distribution measurement method.

(C) Examples of the granular conductive filler include carbon black, granular metal powder (e.g., aluminum, iron, copper), and granular conductive ceramics (e.g., zinc oxide, tin oxide, indium tin oxide), etc. From a conductivity standpoint, carbon black is preferred. The carbon black is not particularly limited as long as it is a commonly available carbon black used for coloring the resin. Typically, carbon black contains lumps formed by agglomeration of primary particles. However, unless it contains a significantly large amount of lumps with a size of 50 ㎛ or larger, the resin composition of the present invention is molded. It is difficult to generate many boots (fine boot protrusions (fine irregularities) where carbon black aggregates) on the surface of the molded body. If the content of particles with a particle diameter of 50 ㎛ or more is 20 ppm or less, the smoothness of the surface of the molded body is likely to increase. The preferred content rate is 5ppm or less.

The total content of (B) fibrous conductive filler and (C) granular conductive filler is 15 to 60% by mass, preferably 20 to 50% by mass, and more preferably 20 to 50% by mass in the liquid crystalline resin composition of the present invention. is 20.5 to 39.5 mass%. If the total content is 15% by mass or more, it is easy to obtain a molded article with improved electromagnetic wave shielding properties. If the total content is 60% by mass or less, the fluidity of the liquid crystalline resin composition is likely to be improved, and a liquid crystalline resin composition excellent in molding processability is easy to be obtained.

The mass ratio of the content of the fibrous conductive filler (B) to the content of the granular conductive filler (C) is 0.30 to 22.0, preferably 0.40 to 21.0, and more preferably 0.50 to 20.0. When the mass ratio is 0.30 or more, the fluidity of the liquid crystalline resin composition is likely to be improved, a liquid crystalline resin composition with excellent molding processability is easy to be obtained, and a molded article with improved electromagnetic wave shielding properties is easy to be obtained. If the mass ratio is 20.0 or less, it is easy to obtain a molded body with improved electromagnetic wave shielding properties.

[(D) Non-conductive filler]

The liquid crystalline resin composition according to the present invention may contain a non-conductive filler. Non-conductive fillers can be used individually or in combination of two or more types. (D) Non-conductive fillers include, for example, plate-shaped non-conductive fillers, granular non-conductive fillers, and fibrous non-conductive fillers.

The median diameter of the plate-shaped non-conductive filler is not particularly limited and may be, for example, 10 to 100 μm, 12 to 50 μm, or 14 to 30 μm. From the viewpoint of electromagnetic wave shielding properties, the electromagnetic wave shield member according to the present invention preferably has small fluctuations in volume resistivity, which is an indicator of conductivity, regardless of the thickness of the molded body, even if it is made of a molded body with a complex shape. If the median diameter of the plate-shaped non-conductive filler is 10 to 100 μm, the thickness dependence of the conductivity of the molded body is likely to be reduced, and it is easy to obtain a molded body with small fluctuation in volume resistivity regardless of the thickness. Examples of plate-shaped non-conductive fillers include talc, mica, and glass flakes.

The median diameter of the fine particle non-conductive filler is not particularly limited, and may be, for example, 0.3 to 50 μm, 0.4 to 25 μm, or 0.5 to 5.0 μm. If the median diameter of the granular non-conductive filler is 0.3 to 50 μm, the thickness dependence of the conductivity of the molded body is likely to be reduced, and it is easy to obtain a molded body with small fluctuation in volume resistivity regardless of the thickness. Examples of the granular non-conductive filler include silicates such as silica, quartz powder, glass beads, glass balloons, glass powder, calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, and wollastonite; Metal oxides such as iron oxide, titanium oxide, zinc oxide, and alumina; Metal carbonates such as calcium carbonate and magnesium carbonate; Metal sulfates such as calcium sulfate and barium sulfate; silicon carbide; silicon nitride; Boron nitride, etc. can be mentioned.

The average fiber length of the fibrous non-conductive filler is not particularly limited, and may be, for example, 50 μm or more and 10 mm or less, 80 μm or more and 7 mm or less, or 100 μm or more and 4 mm or less. If the average fiber length of the fibrous non-conductive filler is 50 μm or more and 10 mm or less, the thickness dependence of the conductivity of the molded body is likely to be reduced, and it is easy to obtain a molded body with small fluctuation in volume resistivity regardless of the thickness. The fiber diameter of the fibrous non-conductive filler is not particularly limited, and may be, for example, 0.2 to 15 μm, 0.25 to 13 μm, or 0.3 to 11 μm. If the fiber diameter of the fibrous non-conductive filler is 0.2 to 15 μm, the thickness dependence of the conductivity of the molded body is likely to be reduced, and it is easy to obtain a molded body with small fluctuation in volume resistivity regardless of the thickness. As the average fiber length of the fibrous non-conductive filler and the fiber diameter of the fibrous non-conductive filler, the average of the values measured in the same manner as described above for the (B) fibrous conductive filler is adopted. Examples of fibrous non-conductive fillers include glass fiber, milled glass fiber, asbestos fiber, silica fiber, silica/alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate whisker, calcium silicate whisker (fibrous and inorganic fibrous substances such as wollastonite.

Since the thickness dependence of the conductivity of the molded body is more likely to be reduced and it is easier to obtain a molded body with a small variation in volume resistivity regardless of thickness, (D) the non-conductive filler is preferably talc, mica, glass flake, or silica. , glass beads, glass balloons, potassium titanate whiskers, calcium silicate whiskers, milled glass fibers, and glass fibers, and more preferably, at least one selected from the group consisting of talc, mica, silica, and glass fibers. There is more than one type to be selected.

(D) The content of the non-conductive filler in the liquid crystalline resin composition of the present invention is preferably 2 to 8% by mass, more preferably 2.3 to 7.7% by mass, and even more preferably 2.5 to 7.5% by mass. am. When the content is 2 to 8% by mass, the fluidity of the liquid crystalline resin composition is likely to be improved, and a liquid crystalline resin composition excellent in molding processability is easy to be obtained.

[Other ingredients]

The liquid crystalline resin composition of the present invention includes other polymers, other fillers, and known substances generally added to synthetic resins, that is, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, etc., to the extent that they do not impair the effect of the present invention. Other ingredients such as flame retardants, colorants such as dyes and pigments, lubricants, crystallization accelerators, crystal nucleating agents, and mold release agents can also be added appropriately depending on the required performance. Other ingredients may be used individually or in combination of two or more.

Other polymers include, for example, epoxy group-containing copolymers. Other polymers may be used individually or in combination of two or more types.

Other fillers refer to fillers other than (B) fibrous conductive fillers, (C) granular conductive fillers, and (D) non-conductive fillers, for example, conductive fillers other than components (B) and (C). You can. Other fillers may be used individually or in combination of two or more types. Examples of conductive fillers other than component (B) and component (C) include plate-shaped conductive fillers.

[Method for preparing liquid crystalline resin composition]

The method for producing the liquid crystalline resin composition of the present invention is not particularly limited. For example, by mixing at least one of the components (A) to (C), optionally the component (D), and optionally other components, and melt-kneading them using a single-screw or twin-screw extruder, liquid crystalline Preparation of the resin composition is performed.

[Liquid crystalline resin composition]

The liquid crystalline resin composition of the present invention obtained as described above preferably has a melt viscosity of 180 Pa·sec or less, more preferably 145 Pa·sec or less, from the viewpoint of fluidity when melted and molding processability. It is more preferable that it is below. In this specification, the melt viscosity is a value obtained by a measurement method based on ISO 11443 under the conditions of a cylinder temperature 10 to 20°C higher than the melting point of the liquid crystalline resin and a shear rate of 1000 sec ^-1 .

[ Example ]

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

<Liquid crystalline resin>

· Liquid crystalline polyesteramide resin (LCP1)

After the following raw materials were added to the polymerization vessel, the temperature of the reaction system was raised to 140°C, and reaction was performed at 140°C for 1 hour. Thereafter, the temperature was again raised to 340°C over 4.5 hours, and the pressure was reduced to 10 Torr (i.e., 1330 Pa) over 15 minutes to perform melt polymerization while acetic acid, excess acetic anhydride, and other low-boiling components were discharged. After the stirring torque reached a predetermined value, nitrogen was introduced to change the pressure from reduced pressure to normal pressure to pressurized state, the polymer was discharged from the bottom of the polymerization vessel, and the strands were pelletized to obtain pellets. The obtained pellet was subjected to heat treatment at 300°C for 2 hours under a nitrogen stream to obtain the target polymer. The melting point of the obtained polymer was 336°C, and the melt viscosity at 350°C was 19.0 Pa·s. In addition, the melt viscosity of the polymer was measured in the same manner as the melt viscosity measurement method described later.

4-hydroxybenzoic acid (HBA); 1380g (60 mol%)

2-hydroxy-6-naphthoic acid (HNA); 157g (5 mol%)

1,4-phenylenedicarboxylic acid (TA); 484g (17.5 mol%)

4,4'-dihydroxybiphenyl (BP); 388g (12.5 mol%)

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

Metal catalyst (potassium acetate catalyst); 110 mg

Acylating agent (acetic anhydride); 1659g

· Liquid crystalline polyester resin (LCP2)

After the following raw materials were added to the polymerization vessel, the temperature of the reaction system was raised to 140°C, and reaction was performed at 140°C for 1 hour. After that, the temperature was again raised to 360°C over 5.5 hours, and the pressure was reduced to 5 Torr (i.e., 667 Pa) over 20 minutes to perform melt polymerization while discharging 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 to pressurized state, the polymer was discharged from the bottom of the polymerization vessel, the strand was pelletized, and the target polymer was obtained as a pellet. The melting point of the obtained polymer was 355°C and the melt viscosity was 10 Pa·s. In addition, the melt viscosity of the polymer was measured in the same manner as the melt viscosity measurement method described later.

4-hydroxybenzoic acid (HBA); 1040g (48 mol%)

6-hydroxy-2-naphthoic acid (HNA); 89g (3 mol%)

1,4-phenylenedicarboxylic acid (TA); 547g (21 mol%)

1,3-phenylenedicarboxylic acid (IA); 91g (3.5 mol%)

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

Potassium acetate catalyst: 110mg

Acetic anhydride: 1644g

<Materials other than liquid crystalline resin>

· Fibrous conductive filler: HTC432 (manufactured by Teijin Co., Ltd., PAN-based carbon fiber, chopped strand, fiber diameter 7㎛, length 6mm)

Carbon black: VULCAN

· Talc: Crown Talc PP (manufactured by Matsumura Sangyo Co., Ltd., talc, median diameter 14.6㎛)

· Mica: AB-25S (Made by Yamaguchi Mika Co., Ltd., Mica, median diameter 25.0㎛)

Silica : Denka fused silica FB-5 SDC (manufactured by Denka Co., Ltd., silica, median diameter 4.0㎛)

· Glass fiber: ECS03T-786H (made by Nippon Electric Glass Co., Ltd., chopped strand, fiber diameter 10㎛, length 3mm)

<Manufacture of liquid crystalline resin composition>

The above components were melt-kneaded at the following cylinder temperature using a twin-screw extruder (TEX30 α type manufactured by Nippon Steel Works Co., Ltd.) in the ratios (unit: mass%) shown in Tables 1 to 3 to obtain liquid crystalline resin composition pellets. .

Cylinder Temperature:

350°C (excluding Example 23)

370°C (Example 23)

<Mel Viscosity>

Using a capilograph type 1B manufactured by Toyo Seiki Works Co., Ltd., at a temperature 10 to 20°C higher than the melting point of the liquid crystalline resin, using an orifice with an inner diameter of 1 mm and a length of 20 mm, a shear rate of 1000/sec conforms to ISO11443. Thus, the melt viscosity of the liquid crystalline resin composition was measured. In addition, the measurement temperature was 350°C for products other than Example 23 and 370°C for Example 23. The results are shown in Tables 1 to 3.

<Volume resistivity>

The pellets of the examples and comparative examples were molded using a molding machine (“SE100DU” manufactured by Sumitomo Heavy Machinery Co., Ltd.) under the following molding conditions, and were formed into flat test pieces 1 of 80 mm x 80 mm x 1 mmt or 80 mm x 80 mm x 2 mmt. Flat test piece 2 was obtained. Using flat test piece 1, a resistivity meter (“Loresta-GP” manufactured by Nitto Seiko Analytech Co., Ltd.) was used to measure the volume resistivity (hereinafter also referred to as “1 mmt volume resistivity”) in accordance with JIS K 7194. was measured. Additionally, using flat test piece 2, a resistivity meter (“Loresta-GP” manufactured by Nitto Seiko Analytech Co., Ltd.) was used to measure the volume resistivity (hereinafter also referred to as “2mmt volume resistivity”) in accordance with JIS K 7194. was measured. Additionally, the difference between the 1 mmt volume resistivity and the 2 mmt volume resistivity was calculated. The results are shown in Tables 1 to 3. When the absolute value of the difference was 0.10 Ω·cm or less, it was evaluated that the variation in volume resistivity was particularly small, regardless of thickness.

〔Molding conditions〕

Cylinder Temperature:

350°C (excluding Example 23)

370°C (Example 23)

Mold temperature: 80℃

Injection speed: 33mm/sec

<Electromagnetic wave shielding properties>

The pellets of Examples and Comparative Examples were molded using a molding machine (“ES3000” manufactured by Nissei Suzy Industries Co., Ltd.) under the following molding conditions to obtain test pieces of 120 mm x 120 mm x 2 mmt. For this test piece, the electromagnetic wave shielding properties at a frequency of 100 MHz were measured by the KEC method. The results are shown in Tables 1 to 3.

〔Molding conditions〕

Cylinder Temperature:

350°C (excluding Example 23)

370°C (Example 23)

Mold temperature: 80℃

Injection speed: 100mm/sec

As is clear from the results shown in Tables 1 to 3, it was confirmed that the compositions of the examples had low melt viscosity and high fluidity, and thus had excellent molding processability. Additionally, the molded articles provided by the compositions of the examples had excellent electromagnetic wave shielding properties. It has been confirmed.

Claims (7)

An electromagnetic wave shield member made of a molded body of a liquid crystalline resin composition containing (A) a liquid crystalline resin, (B) a fibrous conductive filler, and (C) a granular conductive filler,
The total content of the fibrous conductive filler (B) and the granular conductive filler (C) is 15 to 60% by mass,
The mass ratio of the content of the fibrous conductive filler (B) to the content of the granular conductive filler (C) is 0.30 to 22.0,
The electromagnetic wave shield member is an electromagnetic wave shield member that has an electromagnetic wave shielding property of 35 dB or more at a frequency of 100 MHz, measured in accordance with the KEC method. According to paragraph 1,
The total content of the fibrous conductive filler (B) and the granular conductive filler (C) is 20 to 50% by mass,
An electromagnetic wave shield member wherein the mass ratio of the content of the fibrous conductive filler (B) to the content of the granular conductive filler (C) is 0.50 to 20.0. According to claim 1 or 2,
The (B) fibrous conductive filler is carbon fiber,
(C) The electromagnetic wave shield member, wherein the granular conductive filler is carbon black. According to any one of claims 1 to 3,
The liquid crystalline resin composition further contains (D) a non-conductive filler. According to any one of claims 1 to 4,
An electromagnetic wave shield member wherein the content of the non-conductive filler (D) is 2 to 8% by mass. According to clause 4 or 5,
The (D) non-conductive filler is an electromagnetic wave shield, which is at least one selected from the group consisting of talc, mica, glass flakes, silica, glass beads, glass balloons, potassium titanate whiskers, calcium silicate whiskers, milled glass fibers, and glass fibers. absence. According to any one of claims 4 to 6,
The electromagnetic wave shield member (D) wherein the non-conductive filler is at least one selected from the group consisting of talc, mica, silica, and glass fiber.