JPH0571629B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Fields] The present invention has improved moldability, dimensional stability, mechanical properties,
This invention relates to electromagnetic shielding materials that have excellent heat resistance, flame retardancy, chemical resistance, and electromagnetic shielding properties. [Prior Art] In recent years, in electronic equipment such as computers, office machines, audio equipment, and home appliances, electronic elements have become smaller and faster in order to improve processing capacity, and the current consumption has also become smaller. The electromagnetic noise that enters the device becomes similar to the control signal, causing malfunctions. Furthermore, since these elements and circuits themselves have an oscillation function, they emit noise to the outside, causing electromagnetic wave pollution.
Therefore, it is required to provide electromagnetic shielding properties to the plastic housing parts used in these electronic devices. Currently, methods for imparting electromagnetic shielding properties to plastic include a surface treatment method in which a conductive film is formed on the surface of a plastic molded product, and a method in which a conductive filler is mixed into the plastic to make it conductive. be. Methods for forming conductive films include silver, copper, nickel,
Methods include applying paint containing carbon, etc., coating with zinc, plating with copper, nickel, chrome, etc., vacuum deposition, sputtering, ion plating, etc. In addition, to describe the method of mixing conductive filler specifically, conductive carbon black, graphite, metal powder, metal flake, metal fiber,
Conductive fillers such as carbon fiber, metal-coated glass fiber, and carbon fiber are combined with polystyrene,
ABS, polycarbonate, modified PPO, polyurethane, polypropylene, polyvinyl chloride, PBT,
It is mixed into thermoplastic resins such as nylon. Currently, most of the former methods are actually used, but this method has difficulty in mass production because it requires secondary processing after molded product processing, and also has problems with the combination of plastic and metal coatings. There was a problem that adhesion strength tended to be insufficient. On the other hand, although the latter method has many technical problems to be solved, it has great expectations as a future technology with various advantages such as mass production. Development of low-cost fillers due to technological advances,
Thanks to advances in compounding and molding technology, high-performance shielding materials are being announced one after another. [Problems to be solved by the invention] However, in the method of mixing a conductive filler, a large amount of filler must be mixed in order to provide sufficient electromagnetic shielding, which is extremely difficult to achieve with highly viscous resin. However, the kneading properties are poor, and fibrous fillers in particular have a problem in that damage during kneading lowers electromagnetic shielding properties. Furthermore, when fillers other than those in the form of fibers are mixed in, a decrease in mechanical strength becomes a problem. The present invention has better moldability, dimensional stability, mechanical properties, heat resistance, flame retardance, chemical resistance, and electromagnetic shielding properties than the electromagnetic shielding material made by mixing a conductive filler into a general thermoplastic resin as described above. The purpose is to provide an excellent electromagnetic shielding material. [Means for Solving the Problems] In order to achieve this objective, the inventors of the present invention have made extensive studies, and as a result, have formed an anisotropic melt phase that is characterized by low melt viscosity and excellent moldability. The inventors discovered that an electromagnetic shielding material with excellent performance could be obtained by using a melt-processable polymer composition as a binder resin and adding a specific conductive filler to the binder resin, leading to the completion of the present invention. . Specifically, the present invention relates to a moldable electromagnetic shielding material comprising a specific conductive filler mixed into a melt-processable polymer or composition thereof forming an anisotropic melt phase. The conductive filler used in the present invention is a filler that is generally used in filler-containing electromagnetic shielding materials.
The most effective fillers in combination with melt-processable polymers that form anisotropic melt phases are flake-like (plate-like or flake-like) metal powder fillers.
For example, metal flake fillers such as aluminum flakes, stainless steel flakes, brass flakes, and nickel flakes are exemplified. Note that a general flake-like filler, such as a filler whose surface is coated with metal, belongs to the conductive filler of the present invention. These conductive fillers may be used alone or in a mixture of several types as appropriate. The size, shape, etc. of the conductive filler used in the present invention are not particularly limited as long as it is in a so-called flake shape (plate shape or thin piece shape). The content of the conductive filler is 30 to 75% by weight based on the total amount of the electromagnetic shielding material. If it is less than 30% by weight, the effects intended by the present invention cannot be sufficiently obtained, and if it exceeds 75% by weight, moldability will be difficult. The binder resin used in the present invention is a thermoplastic melt processable polymer composition that exhibits optical anisotropy when melted, and is generally classified as a thermotropic liquid crystal polymer. Polymers that form such an anisotropic melt phase have a property in which polymer molecular chains are regularly arranged in parallel in a molten state. The state in which the molecules are arranged in this way is often called the liquid crystal state or the nematic phase of liquid crystalline substances. Such polymers are monomers that are generally elongated, flat, fairly rigid along the long axis of the molecule, and have multiple chain extensions, usually in either a coaxial or parallel relationship. Manufactured from. The nature of the anisotropic melt phase can be confirmed by conventional polarization testing using crossed polarizers.
More specifically, the confirmation of the anisotropic melt phase is based on the Leitz
This can be done by observing a sample placed on a Leitz hot stage under a nitrogen atmosphere at 40x magnification using a polarizing microscope. The above polymer is optically anisotropic. That is, it transmits light when examined between orthogonal polarizers. If the sample is optically anisotropic, polarized light will pass through it even if it is at rest. The constituent components of the polymer forming the anisotropic melt phase as described above include one or more of aromatic dicarboxylic acids and alicyclic dicarboxylic acids, one of aromatic diols, alicyclic diols, and aliphatic diols. Consists of one or more aromatic hydroxycarboxylic acids Consists of one or more aromatic thiol carboxylic acids Consists of one or more of aromatic diols, aromatic thiol phenols Polyesters consisting of one or more of aromatic hydroxyamines and aromatic diamines, etc., and polymers that form an anisotropic melt phase are polyesters consisting only of () and (). It is composed of a combination of polyester ester () consisting of only polyester (), polythiol ester () consisting of polythiol ester () consisting of, polyester amide consisting of () consisting of, polyester amide consisting of (), and the like. Additionally, although not included in the above component combinations, polymers that form anisotropic melt phases include aromatic polyazomethines; specific examples of such polymers include poly(nitrilo-2-methyl-
1,4-phenylenenitriloethyridine-1,4
-phenyleneethyridine); poly(nitrilo-2
-methyl-1,4-phenylenenitrilomethylidine-1,4-phenylenemethylidine); and poly(nitrilo-2-chloro-1,4-phenylenenitrilomethylidine-1,4-phenylenemethylidine) ). Although not included in the above-mentioned combination of components, polyester carbonate is also included as a polymer that forms an anisotropic melt phase. It may consist essentially of 4-oxybenzoyl units, dioxyphenyl units, dioxycarbonyl units and terephthaloyl units. Examples of compounds constituting the above () to () are listed below. Examples of aromatic dicarboxylic acids include terephthalic acid,
4,4'-diphenyldicarboxylic acid, 4,4'-triphenyldicarboxylic acid, 2,6-naphthalene dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenoxyethane-4,4'- dicarboxylic acid, diphenoxybutane-4,4'-dicarboxylic acid, diphenylethane-4,4'-dicarboxylic acid,
Aromatic dicarboxylic acids such as isophthalic acid, diphenyl ether-3,3'-dicarboxylic acid, diphenoxyethane-3,3'-dicarboxylic acid, diphenylethane-3,3-dicarboxylic acid, naphthalene-1,6-dicarboxylic acid acids, or alkyl, alkoxy or halogen substituted products of the above aromatic dicarboxylic acids such as chloroterephthalic acid, dichloroterephthalic acid, bromoterephthalic acid, methylterephthalic acid, dimethylterephthalic acid, ethylterephthalic acid, methoxyterephthalic acid, ethoxyterephthalic acid. etc. can be mentioned. As the alicyclic dicarboxylic acid, trans-1,
4-Cyclohexanedicarboxylic acid, cis-1,4
-Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, or trans-1,4-(1-methyl)cyclohexanedicarboxylic acid, trans-1,4-(1-
Examples include alkyl, alkoxy, or halogen-substituted alicyclic dicarboxylic acids such as (chloro)cyclohexanedicarboxylic acid. Aromatic diols include hydroquinone, resilcin, 4,4'-dihydroxydiphenyl,
4,4'-dihydroxytriphenyl, 2,6-naphthalenediol, 4,4'-dihydroxydiphenyl ether, bis(4-hydroxyphenoxy)ethane, 3,3'-dihydroxydiphenyl,
3,3'-dihydroxydiphenyl ether, 1,
6-naphthalenediol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4
Aromatic diols such as -hydroxyphenyl)methane, chlorohydroquinone, methylhydroquinone, 1-butylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4-chlorresorcin,
Examples include alkyl, alkoxy or halogen substituted products of the above aromatic diols such as 4-methylresorcin. As the alicyclic diol, trans-1,4-
Cyclohexanediol, cis-1,4-cyclohexanediol, trans-1,4-cyclohexanedimethanol, cis-1,4-cyclohexanedimethanol, trans-1,3-cyclohexanediol, cis-1,2-cyclohexanediol, Alicyclic diols such as trans-1,3-cyclohexanedimethanol or the above alicyclic diols such as trans-1,4-(1-methyl)cyclohexanediol and trans-1,4-(1-chloro)cyclohexanediol Examples include alkyl, alkoxy or halogen substituted diols. Examples of aliphatic diols include linear or branched aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, and neopentyl glycol. Aromatic hydroxycarboxylic acids include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxybenzoic acid,
- Aromatic hydroxycarboxylic acids such as hydroxy-2-naphthoic acid and 6-hydroxy-1-naphthoic acid, or 3-methyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, 2,6 -dimethyl-4-hydroxybenzoic acid, 3-methoxy-4-hydroxybenzoic acid,
3,5-dimethoxy-4-hydroxybenzoic acid,
6-hydroxy-5-methyl-2-naphthoic acid,
6-hydroxy-5-methoxy-2-naphthoic acid, 3-chloro-4-hydroxybenzoic acid, 2-
Chloro-4-hydroxybenzoic acid, 2,3-dichloro-4-hydroxybenzoic acid, 3,5-dichloro-4-hydroxybenzoic acid, 2,5-dichloro-4-hydroxybenzoic acid, 3-bromo-4- Aromatic hydroxycarbons such as hydroxybenzoic acid, 6-hydroxy-5-chloro-2-naphthoic acid, 6-hydroxy-7-chloro-2-naphthoic acid, 6-hydroxy-5,7-dichloro-2-naphthoic acid, etc. Examples include alkyl, alkoxy or halogen substituted acids. Examples of aromatic mercaptocarboxylic acids include 4-mercaptobenzoic acid, 3-mercaptobenzoic acid, and 6-mercaptobenzoic acid.
-mercapto-2-naphthoic acid, 7-mercapto-2-naphthoic acid, and the like. As the aromatic dithiol, benzene-1,4
-dithiol, benzene-1,3-dithiol,
Examples include 2,6-naphthalene-dithiol and 2,7-naphthalene-dithiol. Examples of the aromatic mercaptophenol include 4-mercaptophenol, 3-mercaptophenol, 6-mercaptophenol, and 7-mercaptophenol. Aromatic hydroxyamine, aromatic diamines include 4-aminophenol, N-methyl-4-aminophenol, 1,4-phenylenediamine,
N-methyl-1,4-phenylenediamine, N,
N'-dimethyl-1,4-phenylenediamine,
3-aminophenol, 3-methyl-4-aminophenol, 2-chloro-4-aminophenol, 4-amino-1-naphthol, 4-amino-
4'-hydroxydiphenyl, 4-amino-4'-hydroxydiphenyl ether, 4-amino-4'-
Hydroxydiphenylmethane, 4-amino-4'-
Hydroxydiphenyl sulfide, 4,4'-diaminosulfide (thiodianiline), 4,4'-diaminodiphenylsulfone, 2,5-diaminotoluene, 4,4'-ethylenedianiline, 4,4' −
Diaminodiphenoxyethane, 4,4'-diaminodiphenylmethane (methylene dianiline), 4,
Examples include 4'-diaminodiphenyl ether (oxydianiline). The above polymer () consisting of each of the above components
Among the above-mentioned polymers, () may or may not form an anisotropic melt phase depending on the constituent components, the composition ratio in the polymer, and the sequence distribution. Limited to those that form an anisotropic melt phase. The above (), (), () polyester and () polyester amide which are polymers forming an anisotropic melt phase suitable for use in the present invention are:
They can be produced by a variety of ester-forming methods that allow the reaction of organic monomer compounds having functional groups that form the required repeating units by condensation. For example, the functional groups of these organic monomer compounds may be carboxylic acid groups, hydroxyl groups, ester groups, acyloxy groups, acid halides, amine groups, and the like. The above organic monomer compounds can be reacted without the presence of a heat exchange fluid by a melt acidolysis method. In this method, the monomers are first heated together to form a molten solution of the reactants. As the reaction continues, solid polymer particles become suspended in the liquid. Vacuum may be applied to facilitate removal of by-product volatiles (eg acetic acid or water) during the final stage of condensation. Slurry polymerization techniques can also be employed to form fully aromatic polyesters suitable for use in the present invention. In this process, a solid product is obtained suspended in a heat exchange medium. Regardless of whether the above-mentioned melt acidolysis method or slurry polymerization method is employed, the organic monomer reactant for inducing the fully aromatic polyester is in a modified form (i.e., lower (as an acyl ester). The lower acyl group preferably has about 2 to 4 carbon atoms. Preferably, an acetate ester of such an organic monomer reactant is subjected to the reaction. Furthermore, representative examples of catalysts that can optionally be used in either the melt acidolysis method or the slurry method include dialkyltin oxides (e.g., dibutyltin oxide), diaryltin oxides, titanium dioxide, antimony trioxide, alkoxytitanium silicates, titanium alkoxides, alkali and alkaline earth metal salts of carboxylic acids (e.g. zinc acetate),
Lewis (e.g. BF ₃ ), hydrogen halides (e.g. HCl)
Examples include gaseous acid catalysts such as. The amount of catalyst used is generally based on the total weight of monomers in approximately
0.001 to 1% by weight, especially about 0.01 to 0.2% by weight. Fully aromatic polymers suitable for use in the present invention tend to be substantially insoluble in common solvents and are therefore unsuitable for solution processing. However, as previously mentioned, these polymers can be readily processed using conventional melt processing methods. Particularly preferred fully aromatic polymers are somewhat soluble in pentafluorophenol. Fully aromatic polyesters suitable for use in the present invention generally have a weight average molecular weight of about 2,000 to 200,000;
Preferably about 10,000 to 50,000, particularly preferably about
20000-25000. On the other hand, suitable fully aromatic polyesteramides generally have a molecular weight of about 5000 to
50000, preferably about 10000-30000, e.g. 15000
~17000. Such molecular weight measurements can be carried out by gel permeation chromatography as well as other standard methods of measuring polymers that do not involve solution formation, such as quantification of end groups by infrared spectroscopy on compression molded films. Alternatively, the molecular weight can be measured using a light scattering method using a pentafluorophenol solution. The fully aromatic polyesters and polyesteramides described above also have a logarithmic viscosity (IV) of at least about 2.0 dl/g, such as from about 2.0 to 10.0 dl/g, when dissolved in pentafluorophenol at 0.1% concentration by weight at 60°C. generally indicated. Particularly preferred anisotropic melt phase forming polyesters for use in the present invention include repeating units containing naphthalene moieties such as 6-hydroxy-2-naphthoyl, 2,6-dihydroxynaphthalene and 2,6-dicarboxynaphthalene. It is contained in an amount of about 10 mol% or more. Preferred polyesteramides are those containing repeating units of the naphthalene moiety described above and a moiety consisting of 4-aminophenol or 1,4-phenylenediamine. Specifically, the details are as follows. (1) A polyester consisting essentially of the following repeating units and:

【formula】

[Formula] The polyester contains about 10 to 90 mole percent units and about 10 to 90 mole percent units. In one embodiment, the units are present in an amount of about 65-85 mole%, preferably about 70-80 mole% (eg, about 75 mole%). In another embodiment, the units are about 15-35
It is present in amounts as low as mole %, preferably about 20-30 mole %. In addition, at least some of the hydrogen atoms bonded to the ring may optionally be
It may be substituted with a substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl, and a combination thereof. (2) A polyester consisting essentially of the following repeating units, and:

【formula】

【formula】

[Formula] This polyester contains approximately 30-70 mole percent units. The polyester preferably has about 40-60 mole% units, about 20-30 mole%
units, and about 20-30 mol% units. In addition, at least a portion of the hydrogen atoms bonded to the ring may optionally be a group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl, or a combination thereof. may be substituted with a substituent selected from. (3) A polyester consisting essentially of the following repeating units, and:

【formula】

[ka]

【formula】

[Formula] (wherein R means methyl, chloro, bromo, or a combination thereof, and is a substituent for a hydrogen atom on an aromatic ring), and contains about 20 to 60 mol% of units; about 5 to 18 mole percent, about 5 to 35 mole percent units, and about 20 to 40 mole percent units. The polyester preferably has about 35-45 mole% units, about 10-15 mole% units, about 15-25 mole% units.
units, and about 25 to 35 mole % units. However, the total molar concentration with the unit is substantially equal to the molar concentration of the unit. In addition, at least some of the hydrogen atoms bonded to the ring are
Optionally, it may be substituted with a substituent selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl, and a combination thereof. This fully aromatic polyester is
0.3w/v for pentafluorophenol at 60℃
At least 2.0 dl/g when dissolved in % concentration
For example, they generally exhibit a logarithmic viscosity of 2.0 to 10.0 dl/g. (4) A polyester consisting essentially of the following repeating units, and:

【formula】

[Formula] Dioxyaryl unit represented by the general formula [-O-Ar-O]- (wherein Ar means a divalent group containing at least one aromatic ring), the general formula

It consists of a dicarboxyaryl unit represented by the formula: (wherein Ar' means a divalent group containing at least one aromatic ring), and the unit is about 20 to 40 mol%, and the unit is 10 mol % but not more than about 50 mole %, more than 5 mole % and not more than about 30 mole % units, and more than 5 mole % and not more than about 30 mole % units. This polyester is preferably
about 20 to 30 mol% (e.g., about 25 mol%) units,
about 25 to 40 mol% (e.g., about 35 mol%) units,
about 15 to 25 mol% (e.g., about 20 mol%) units,
and contains about 15 to 25 mol% (eg, about 20 mol%) units. In addition, at least a portion of the hydrogen atoms bonded to the ring may optionally be a group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl, or a combination thereof. may be substituted with a substituent selected from. units are those in which the divalent bonds connecting these units to other units on either side within the polymer backbone are arranged symmetrically on one or more aromatic rings (e.g., on a naphthalene ring). It is preferable that they be symmetrical in the sense that they are arranged at para positions with respect to each other or on a diagonal ring. However, asymmetric units such as those derived from resorcinol and isophthalic acid can also be used. Preferred dioxyaryl units are

and the preferred dicarboxyaryl unit is

It is [ ]. (5) A polyester consisting essentially of the following repeating units, and:

[Chemical formula] Dioxyaryl unit represented by the general formula [-O-Ar-O]- (wherein Ar means a divalent group containing at least one aromatic ring), the general formula

It consists of a dicarboxyaryl unit represented by the formula: (wherein Ar' means a divalent group containing at least one aromatic ring); 45 mol%, and contains units in an amount of 5 to 45 mol%. The polyester preferably contains about 20-80 mole% units, about 10-40 mole%
units, and about 10 to 40 mol% units. More preferably, the polyester contains about 60 to 80 mole percent units, about 10 to 20 mole percent units, and about 10 to 20 mole percent units. In addition, at least a portion of the hydrogen atoms bonded to the ring may optionally be a group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl, or a combination thereof. may be substituted with a substituent selected from. Preferred dioxyaryl units are

and the preferred dicarboxyaryl unit is

It is [ ]. (6) A polyesteramide consisting essentially of the following repeating units, and:

[ka] general formula

[Formula] (wherein A means a divalent group containing at least one aromatic ring or divalent trans-cyclohexane), general formula [-Y-Ar-Z]- (wherein Ar is at least one A divalent group containing aromatic rings, Y is O,
NH or NR, Z means NH or NR respectively, R means an alkyl group having 1 to 6 carbon atoms or an aryl group), general formula [-O-Ar'-O]- (in the formula, Ar′ means a divalent group containing at least one aromatic ring), and consists of about 10 to 90 mol% of units, about 5 to 45 mol% of units, about 5 to 45 mol% of units, and contains the unit in an amount of about 0 to 40 mol%. In addition, at least a portion of the hydrogen atoms bonded to the ring may optionally be a group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, halogen, phenyl, substituted phenyl, or a combination thereof. may be substituted with a substituent selected from. Preferred dicarboxyaryl units are

[ka] and the preferred unit is

[expression] or

【formula】 and the preferred dioxyaryl unit is

〔Example〕

The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto. Example 1 Polymer A forming an anisotropic melt phase (details later)
70% by weight was mixed with 30% by weight of aluminum frames having an average size of 1 x 1.25 x 0.025 (mm), and the mixture was kneaded and extruded using an extruder to produce pellets. Next, this pellet is used in an injection molding machine to measure bending strength (ASTM D-790), Izot impact strength (ASTM D-256), and heat distortion temperature (ASTM D-
648) Test pieces for measurement were each formed and subjected to testing. Also, electromagnetic shielding characteristics are 200 x 200 x 3 (mm)
Measurements were made at 100MHz using a molded plate. Example 2 Using polymer B (details later) as the resin,
Further, a test piece was molded in the same manner as in Example 1 except that the content of aluminum flakes was 35% by weight, and was subjected to a test. Example 3 Using polymer C (details later) as the resin,
Further, a test piece was formed in the same manner as in Example 1 except that the content of aluminum flakes was 40% by weight, and was subjected to a test. Example 4 Using Polymer D (details later) as the resin,
Further, a test piece was molded in the same manner as in Example 1 except that the content of aluminum flakes was 35% by weight, and was subjected to a test. The injection molding conditions varied depending on the type and amount of resin and filler added, and were carried out at a cylinder temperature of 280 to 350°C, a mold temperature of 100 to 170°C, and an injection pressure of 800 to 1500 kg/cm ² . Comparative Example 1 60% by weight of ABS resin was mixed with 40% by weight of the same aluminum flakes as in Example 1, and the mixture was kneaded and extruded using an extruder to form pellets. Next, this pellet is used to control the cylinder temperature in an injection molding machine.
Test pieces for measuring physical properties were molded in the same manner as in Example 1 under the conditions of 220 to 230°C, mold temperature of 80°C, and injection pressure of 1000 kg/cm ² and subjected to testing. Comparative Examples 2 to 6 For comparison, similar tests were conducted on resin molded products to which no conductive filler was added. The results of Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 1. Example 5 Using polymer C (details later) as the resin,
Further, a test piece was prepared in the same manner as in Example 1 except that the content of aluminum flakes was 65% by weight, and was subjected to the test. Even though the content of aluminum flakes was increased to 65% by weight, the electromagnetic shielding material using Polymer C specified in the present invention can be sufficiently injection molded, and the electromagnetic shielding property is 52 [dB].
It was good. Comparative Example 7 35% by weight of ABS resin was mixed with 65% by weight of the same aluminum flakes as in Example 1, pellets were made in the same manner as in Comparative Example 1, and injection molding was attempted, but molding was impossible and the shielding effect was poor. It was also impossible to measure it. Comparative Example 8 70% by weight of polyethylene terephrate (intrinsic viscosity 1.1), which is a non-liquid crystalline polyester, was mixed with 30% by weight of the same aluminum flakes as in Example 1,
Although melt-kneading extrusion was attempted, stable extrusion was not possible, and therefore physical property evaluation was not possible. The polymers A, B, C, and D used as the binder resin and forming the anisotropic melt phase have the following structural units.

[ka]

[ka]

【formula】

[Chemical formula] <Resin A> 1081 parts by weight of 4-acetoxybenzoic acid, 460 parts by weight of 6-acetoxy-2-naphthoic acid, 166 parts by weight of isophthalic acid, 194 parts by weight of 1,4-diacetoxybenzene
The weight part was charged into a reactor equipped with a stirrer, a nitrogen inlet tube and a distillation tube, and the mixture was heated under a nitrogen stream.
Heated to 260°C. The mixture was vigorously stirred at 260°C for 2.5 hours and then at 280°C for 3 hours while distilling acetic acid from the reactor. Furthermore, the temperature was raised to 320° C., and after stopping the introduction of nitrogen, the pressure in the reactor was gradually reduced to 0.1 mmHg after 15 minutes, and the mixture was stirred at this temperature and pressure for 1 hour. The resulting polymer had an intrinsic viscosity of 5.0, measured in pentafluorophenol at 60° C. at a concentration of 0.1% by weight. <Resin B> 1081 parts by weight of 4-acetoxybenzoic acid, 2,6-
489 parts by weight of diacetoxynaphthalene and 332 parts by weight of terephthalic acid were charged into a reactor equipped with a stirrer, a nitrogen inlet tube, and a distillation tube, and the mixture was heated to 250° C. under a nitrogen stream. The mixture was vigorously stirred at 250°C for 2 hours and then at 280°C for 2.5 hours while distilling acetic acid from the reactor. Furthermore, the temperature was raised to 320℃,
After stopping the introduction of nitrogen, the pressure in the reactor was gradually reduced to 0.2 mmHg after 30 minutes, and at this temperature,
Stirred at pressure for 1.5 hours. The resulting polymer had an intrinsic viscosity of 2.5, measured in pentafluorophenol at a concentration of 0.1% by weight at 60°C. <Resin C> 1261 parts by weight of 4-acetoxybenzoic acid, 691 parts by weight of 6-acetoxy-2-naphthoic acid, a stirrer,
The mixture was charged into a reactor equipped with a nitrogen inlet tube and a distillation tube, and heated to 250° C. under a nitrogen stream.
The mixture was vigorously stirred at 250°C for 3 hours and then at 280°C for 2 hours while distilling acetic acid from the reactor. Furthermore,
After increasing the temperature to 320℃ and stopping the introduction of nitrogen, gradually reduce the pressure in the reactor 30 and reduce the pressure to 0.1 after 20 minutes.
The temperature was lowered to mmHg, and the mixture was stirred at this temperature and pressure for 1 hour. The resulting polymer had an intrinsic viscosity of 5.4, measured in pentafluorophenol at 60° C. at a concentration of 0.1% by weight. <Resin D> 1612 parts by weight of 6-acetoxy-2-naphthoic acid,
290 parts by weight of 4-acetoxyacetanilide, 249 parts by weight of terephthalic acid, and 0.4 parts by weight of sodium acetate were charged into a reactor equipped with a stirrer, a nitrogen introduction pipe, and a distillation pipe, and the mixture was heated to 250°C under a nitrogen stream. did. 250 while distilling acetic acid from the reactor.
Stir vigorously for 1 hour at 300°C and then for 3 hours at 300°C.
Further, the temperature was raised to 340°C, and after stopping the introduction of nitrogen, the pressure inside the reactor was gradually reduced, and after 30 minutes, the pressure was lowered to 0.2 mmHg, and stirring was continued at this temperature and pressure for 30 minutes. The resulting polymer had an intrinsic viscosity of 3.9, measured in pentafluorophenol at a concentration of 0.1% by weight at 60°C.

〔Effect of the invention〕

As is clear from the results in Table 1, the electromagnetic shielding material of the present invention has improved physical properties such as impact strength and electromagnetic shielding properties compared to conventional products using thermoplastic, and can be used in electronic equipment such as computer equipment. It is suitable as a plastic housing part.

Claims (1)

[Claims] 1 Conductive filler made of flaky metal powder (30 to 75% by weight based on the total amount of electromagnetic shielding material),
An electromagnetic shielding material for molding, which is incorporated into a melt-processable polymer or composition thereof that forms an anisotropic melt phase.