JP2002176287A - Resin composition for electromagnetic wave shield - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for an electromagnetic wave shield which is excellent in electromagnetic wave shield characteristics, especially in an initial electromagnetic wave shield characteristics, with less degradation in electromagnetic wave shield characteristics under a heat shock. SOLUTION: The electromagnetic wave shield resin composition comprises (A) a thermo-plastic polyester 100 pts.wt. of apparent molten viscosity 10-200 Pa.s; (B) a fabric conductive filler 5-150 pts.wt. of volume resistivity 1×10-2 Ωcm or less; and (C) an antistatic polymer 5-200 pts.wt. of surface resistivity 1×1011 or less, melting point 100 deg.C or above, apparent molten viscosity 10-1000 Pa.s, and apparent molten viscosity ratio of 0.01-3 relative to the thermo-plastic polyester (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition suitable for use in shielding electromagnetic waves.

[0002]

2. Description of the Related Art In general, polyester resins are electrically insulating substances. However, in many cases, they are required to have conductivity when used for electric and electronic parts, and furthermore have to have conductivity to shield electromagnetic waves. Often done.

[0003] As a method for making the thermoplastic polyester resin conductive, there is a method using a surface treatment such as conductive paint, electromagnetic wave shielding plating, and zinc spraying. In addition, metal powder, carbon black, metal flakes, and metal coating are contained in the thermoplastic polyester resin. There is a method of molding by mixing a conductive filler such as carbon fiber.

[0004] However, in the method by surface treatment, a complicated processing step is required for conducting conductive treatment on the surface of the molded casing, and the conductive layer is easily peeled off.

[0005] Further, in the method of molding by blending a conductive filler into a resin, there is no need for a special post-process and there is no fear of peeling of the conductive layer, but there are still various problems. For example,
A resin composition to which a particulate conductive filler such as carbon black, metal powder, or metal flake is added has poor conductivity and does not have a sufficient shielding effect. If the compounding amount is increased in order to obtain a sufficient shielding effect, the mechanical properties will be significantly reduced.

In a resin composition containing a fibrous conductive filler such as copper fiber, stainless steel fiber, carbon fiber, metal-coated carbon fiber, etc., the mechanical and thermal properties are improved, and the particulate conductive filler is used. Although the conductivity is better than when added, due to poor dispersion of the fibrous conductive filler,
High shielding effect cannot be obtained.

A method in which a polyester elastomer, a fibrous conductive filler and a conductive powder are used in combination is disclosed in JP-A-9-25.
Although disclosed in Japanese Patent No. 397, the strength is not yet sufficient, the shielding effect depends on the dispersion state of the filler, and a high shielding effect cannot be obtained.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resin composition for electromagnetic wave shielding which is excellent in electromagnetic wave shielding properties.
Further, an object of the present invention is to provide a resin composition for electromagnetic wave shielding, in which a decrease in electromagnetic wave shielding properties due to heat shock is small.

The Advantest method is a method for evaluating the electromagnetic wave shielding property. The present invention relates to an electromagnetic wave (100 MH)
z) The initial value of the shield value is 40 dB or more, and -40
An object of the present invention is to obtain an electromagnetic wave shielding resin composition having an electromagnetic wave (100 MHz) shield value after 100 cycles of heat shock at 120 ° C./120° C. of 70% or more of an initial value. This electromagnetic wave shielding property is a characteristic particularly required for a shielded connector for an electric vehicle, and an object of the present invention is to further provide an electromagnetic wave shielding resin composition for a shielded connector for an electric vehicle.

[0010]

That is, the present invention provides:
(A) 100 parts by weight of a thermoplastic polyester having an apparent melt viscosity of 10 to 200 Pa · s, (B) a volume resistivity of 1 ×
5 to 150 parts by weight of fibrous conductive filler of 10 ^-2 Ωcm or less and (C) surface resistivity of 1 × 10 ¹¹ Ω or less, melting point of 100 ° C. or more, and apparent melt viscosity of 10 to 1000
Antistatic polymer 5 having a Pa.s and an apparent melt viscosity ratio of 0.01 to 3 with respect to thermoplastic polyester (A)
It is a resin composition for electromagnetic wave shielding comprising up to 200 parts by weight.

The present invention further provides an antistatic polymer (C)
The above-mentioned resin composition for electromagnetic wave shielding, comprising 0.1 to 40% by weight of (D) conductive powder with respect to 100% by weight.

The electromagnetic wave shielding resin composition of the present invention comprises:
The initial value of the electromagnetic wave (100 MHz) shield value according to the Advantest method is 40 dB or more, and −40 ° C./120
C. After 100 cycles of heat shock at 100.degree.
MHz) It is possible to provide an electromagnetic wave shielding property in which the shielding value is 70% or more of the initial value.

First, the definition of terms in this specification will be described.

The apparent melt viscosity of the thermoplastic polyester (A) is apparent shear rate at 260 ° C. of 1000 sec.
The apparent melt viscosity at c- ¹ .

The apparent melt viscosity of the thermoplastic polyester (A) is a value when it is blended for producing the resin composition for electromagnetic wave shielding of the present invention, and is a value as a single component.

The surface resistivity of the antistatic polymer (C) is a value measured at a measurement voltage of 500 V, and is a value measured before being mixed into the composition. This is a measured value when the conductive powder (D) is not contained.

The apparent melt viscosity of the antistatic polymer (C) is apparent shear rate at 260 ° C. of 1000 sec ^−1.
It is the apparent melt viscosity in.

The ratio of the apparent melt viscosity of the antistatic polymer (C) to the thermoplastic polyester (A) is determined by the apparent shear rate of the thermoplastic polyester (A) at 260 ° C. of 1
Apparent shear rate 1 at 260 ° C. of antistatic polymer (C) to apparent melt viscosity at 000 sec ⁻¹
It is the ratio of the apparent melt viscosity at 000 sec ^-1 .

The ratio of the surface resistivity, the apparent melt viscosity of the antistatic polymer (C) and the apparent melt viscosity to the thermoplastic polyester (A) is blended to produce the resin composition for electromagnetic wave shielding of the present invention. It is a value at the time, and is a value as a single component.

In the numerical notation, a × 10 ^b is represented by “aE
b "and a × 10 ^-b may be described as“ aE-b ”. For example, 1 × 10 ^-2 may be described as“ 1E-2 ”.

Hereinafter, the present invention will be described in more detail.

[Thermoplastic polyester (A)] The thermoplastic polyester (A) comprises a dicarboxylic acid component and a diol component. Examples of the dicarboxylic acid component include terephthalic acid and 2,6-naphthalenedicarboxylic acid. Examples of the diol component include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, and neopentyl glycol.

As a thermoplastic polyester (A), polybutylene terephthalate,
Polypropylene terephthalate, polyethylene terephthalate, polybutylene-2,6-naphthalenedicarboxylate and polyethylene-2,6-naphthalenedicarboxylate are preferred, and polybutylene terephthalate is particularly preferred.

The thermoplastic polyester (A) may be formed by copolymerizing, for example, 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less of the copolymer components based on all dicarboxylic acid components. Good.

Examples of such a copolymer component include terephthalic acid, isophthalic acid, and phthalic acid; alkyl-substituted phthalic acids such as methyl terephthalic acid and methyl isophthalic acid;
Naphthalenedicarboxylic acids such as naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 1,5-naphthalenedicarboxylic acid; 4,4′-diphenyldicarboxylic acid;
Diphenyldicarboxylic acid such as 3,4'-diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid such as 4,4'-diphenoxyethanedicarboxylic acid; succinic acid, adipic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid Aliphatic or alicyclic dicarboxylic acids such as acids; alicyclic diols such as 1,4-cyclohexanedimethanol; dihydroxybenzenes such as hydroquinone and resorcin; 2,2′-bis (4-hydroxyphenyl) -propane, bis Bisphenols such as (4-hydroxyphenyl) -sulfone; aromatic diols such as ether diols obtained from bisphenols and glycols such as ethylene glycol; ε-oxycaproic acid, hydroxybenzoic acid, hydroxyethoxybenzoic acid, etc. Oxy It can be exemplified carboxylic acid.

In the thermoplastic polyester (A), as a branching component, a polyfunctional ester-forming acid such as trimesic acid or trimellitic acid, or a polyfunctional ester-forming ability such as glycerin, trimethylolpropane or pentaerythritol. May be copolymerized with 1.0 mol% or less, preferably 0.5 mol% or less, more preferably 0.3 mol% or less of the total dicarboxylic acid component.

The thermoplastic polyester (A) has an intrinsic viscosity of preferably 0.6 to 1.2, more preferably,
0.6 to 0.9. If the intrinsic viscosity is less than 0.6, sufficient mechanical properties cannot be obtained, which is not preferable. If the intrinsic viscosity is more than 1.2, the melt viscosity is high, the fluidity is reduced, and the moldability is impaired. Here, the intrinsic viscosity is a value calculated from a measured value in orthochlorophenol at 35 ° C.

The thermoplastic polyester (A) has a temperature of 260 ° C.
It is necessary that the apparent melt viscosity at an apparent shear speed of 1000 sec ^-1 is 10 to 200 Pa · s, and preferably 10 to 120 Pa · s. 1
If it is less than 0 Pa · s, sufficient mechanical properties cannot be obtained,
If it exceeds 200 Pa · s, the shielding effect of electromagnetic waves is reduced.

[Fibrous Conductive Filler] The fibrous conductive filler (B) has a volume resistivity of 1 × 10 ^-2 Ωcm.
The following fibrous conductive filler is used. Preferred as the fibrous conductive filler (B) satisfying this condition is:
Nickel coated carbon fiber, metal fiber,
It is a metal whisker. When metal fibers are used as the fibrous conductive filler, preferred metal fibers are metal fibers produced by a drawing method, a melt extrusion method, a melt extraction method, a cutting method or a plating method. Preferred metals for the metal fiber are Fe, Ni, Cu, Al, Pb, SUS (chromium steel), and Zn. The most suitable of these is
Nickel coated carbon fiber. In applications requiring mechanical properties, nickel-coated carbon fibers may be used in combination with glass fibers or carbon fibers.

The amount of the fibrous conductive filler (B) is as follows:
5-150 parts by weight with respect to 100 parts by weight of the thermoplastic resin,
Preferably it is 10 to 90 parts by weight. If the fibrous conductive filler exceeds 150 parts by weight, extrudability and moldability deteriorate. Further, it is disadvantageous in terms of cost and is not practical. If the fibrous conductive filler is less than 5 parts by weight, a good electromagnetic wave shielding effect cannot be obtained.

[Antistatic Polymer] The antistatic polymer (C) is
It is necessary that the surface resistivity is 1 × 10 ¹¹ Ω or less. If the surface resistivity exceeds 1 × 10 ¹¹ Ω, a good electromagnetic wave shielding effect cannot be provided.

The antistatic polymer (C) needs to have a melting point of 100 ° C. or higher. If the melting point is less than 100 ° C., there is a problem in heat resistance when compounding with engineering plastics such as polyester, and sufficient electromagnetic wave shielding properties cannot be provided.

The antistatic polymer (C) needs to have an apparent melt viscosity of 10 to 1000 Pa · s. If the apparent melt viscosity is less than 10 Pa · s, the antistatic polymer is too finely dispersed or unevenly distributed in the thermoplastic resin, so that sufficient shielding properties cannot be provided. 1000Pa · s
Exceeding this causes problems in extrudability and moldability.

The antistatic polymer (C) has an apparent melt viscosity ratio of 0.01 to 0.01 to the thermoplastic polyester (A).
3, preferably 0.1 to 2. If the apparent melt viscosity ratio is less than 0.01, the antistatic polymer is too finely dispersed or unevenly distributed in the thermoplastic resin, so that good shielding properties cannot be provided. If it exceeds 3, the antistatic polymer may be too unevenly distributed to provide good shielding properties, or problems may occur in extrudability and moldability.

Examples of the antistatic polymer (C) include polyetheresteramide, polyethylene glycol-based polyester elastomer, polyethylene glycol methacrylate copolymer, poly (ethylene oxide / propylene oxide) copolymer, and poly (epichlorohydrin / ethylene oxide) copolymer. A polymer can be preferably used.

Examples of the polyetheresteramide include a polyethylene glycol-based polyamide copolymer and a polyethylene glycol-based polyesteramide copolymer. Among these, a polyetheresteramide derived (polymerized) from a polyamide (C1) having carboxyl groups at both ends and an ethylene oxide adduct of bisphenols (C2) is preferable.

The polyamide (C1) having carboxyl groups at both ends preferably has a number average molecular weight of 500 to 5,000, more preferably 500 to 3,000. If the number average molecular weight is less than 500, the heat resistance of the polyether ester amide itself decreases, and if it exceeds 5,000, the reactivity decreases, which undesirably increases the production cost of the polyether ester amide.

The ethylene oxide adduct of bisphenols (C2) preferably has a number average molecular weight of 1600 to 3000, more preferably 32 to 60 in terms of moles of ethylene oxide. If the number average molecular weight is less than 1600, conductive properties of 1E + 11 Ω / □ or less cannot be imparted. If the number average molecular weight exceeds 3,000, reactivity decreases, and the production cost of polyetheresteramide increases, which is not preferable.

The polyetheresteramide can be produced by using a known method. An amide-forming monomer and a dicarboxylic acid are reacted to form a polyamide (C1) having carboxyl groups at both ends, to which an ethylene oxide adduct of bisphenols (C2) is added, and a polymerization reaction is performed at high temperature and reduced pressure. And a method for obtaining a polyetheresteramide.

Examples of the polyethylene glycol-based polyester elastomer include a polyetherester block copolymer.

Particularly preferred as the polyetherester block copolymer are (a) a dicarboxylic acid component comprising 60 to 100 mol% of a terephthalic acid component and 40 to 0 mol% of an isophthalic acid component, based on the total acid component;
(B) a poly (alkylene oxide) glycol component represented by the following general formula (I),

[0042]

Embedded image

(Where X is a substituent —H, —CH ₃ ,
_{-CH 2 Cl, -CH 2 Br,} -CH 2 I or -CH ₂ O
Represents CH ₃ , wherein n and m are n ≧ 0, m ≧ 0 and 120 ≧
It is assumed that (n + m) ≧ 20 is satisfied. When m is 2 or more, X may be the same or different. (C) Tetramethylene glycol 65 to 100 mol based on all glycol components (excluding (b) component)
1% and a glycol component consisting of 35 to 0 mol% of ethylene glycol, and the copolymerization amount of the component (b) is 40% of the total glycol component (including the component (b)). ８０80% by weight of a polyetherester block copolymer.

The poly (alkylene oxide) glycol component of the component (b) of the copolymer may be a random copolymer or a block copolymer.

The tetramethylene glycol component in this polyetherester block copolymer is 65% based on the total glycol component (excluding the component (ii)).
It is preferably at least mol%. If the content of the tetramethylene glycol component is less than 65 mol%, the moldability deteriorates, which is not preferable.

In the polyetherester block copolymer, dicarboxylic acids other than terephthalic acid and isophthalic acid, for example, phthalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, Melitic acid, pyromellitic acid, naphthalenedicarboxylic acid,
Cyclohexanedicarboxylic acid may be copolymerized. When these components are copolymerized, the amount of copolymerization is preferably less than 40 mol%, more preferably less than 20 mol%, based on the total amount of the acid components.

In the polyetherester block copolymer, diols other than tetramethylene glycol and ethylene glycol, for example,
Trimethylene glycol, 1,5-pentanediol,
1,6-hexanediol, diethylene glycol,
1,4-cyclohexanediol and 1,4-cyclohexanedimethanol may be copolymerized.

When these components are copolymerized, the amount of copolymerization is preferably less than 40 mol%, more preferably 2 mol%, based on the total amount of glycol components (excluding the component (ii)).
Less than 0 mol%.

The polyetherester block copolymer includes a poly (alkylene oxide) glycol component (II)
Is copolymerized, and the copolymerization amount of the component (b) is preferably 40 to 80% by weight, more preferably 40 to 70% by weight of all glycol components (including the component (B)). . If it is less than 40% by weight, characteristics of 1E + 11 Ω / □ or less cannot be obtained, and if it is more than 80% by weight, fusion and agglomeration of the polymer occur, which is not preferable because of problems in the process.

The poly (alkylene oxide) glycol component (b) is preferably represented by the following general formula (I).

[0051]

Embedded image

In the above formula (I), X represents a hydrogen atom (-
H) or a substituent _{-CH 3, -CH 2 Cl, -CH} 2 B
r, represents a -CH ₂ I or -CH ₂ OCH _3.

If X is a complex group other than these, it is not preferable because it is difficult to increase the degree of polymerization of the copolymer due to steric hindrance. Those in which the main chain of the polyethylene glycol unit is directly substituted with a halogen or an alkoxy group are not preferred because of high polymer degradability. X is preferably a hydrogen atom.

In the above formula (I), n and m are n ≧ 0, m
It is preferable to satisfy ≧ 0 and 120 ≧ (n + m) ≧ 20. When the value of (n + m) is less than 20, the blockability of the block copolymer decreases, and it is difficult to obtain a characteristic of 1E + 11 Ω / □ or less, which is not preferable. (N + m)
Exceeds 120, the degree of polymerization decreases, and it is difficult to obtain a copolymer having a sufficient degree of polymerization. When m is 2 or more, X may be the same or different. The poly (alkylene oxide) glycol component (b) may be a random copolymer or a block copolymer per se.

The compounding amount of the antistatic polymer (C) is 5 to 200 parts by weight, preferably 5 to 100 parts by weight, more preferably 5 to 100 parts by weight based on 100 parts by weight of the thermoplastic polyester.
-30 parts by weight. When the amount of the antistatic polymer exceeds 200 parts by weight, the mechanical strength and productivity are reduced. When the amount is less than 5 parts by weight, a favorable electromagnetic wave shielding effect cannot be obtained by fusion with the fibrous conductive filler.

[Conductive Powder] The conductive powder (D) is made of a conductive substance and is in the form of a powder. The conductive powder (D) preferably has an average particle size of 1 to 500 m.
μ, more preferably 10 to 100 μm.
As the conductive powder, conductive carbon and metal powder can be used, and conductive carbon is preferable. As conductive carbon, Ketjen black, acetylene black,
Various furnace-based conductive carbons can be exemplified, and Ketjen Black is particularly preferred.

When the conductive powder (D) is contained in the resin composition for electromagnetic wave shielding of the present invention, its content is preferably 0.1 to 40% by weight per 100% by weight of the antistatic polymer (C). Is 2 to 20% by weight, more preferably 5 to 20% by weight.
It is 12% by weight. If it exceeds 40% by weight, the mechanical properties decrease. If the content is less than 0.1% by weight, the effect of further improving the electromagnetic wave shielding property by blending the conductive powder (D) cannot be expected.

The conductive powder (D) is composed of an antistatic polymer (C)
It is preferable to distribute it at a high concentration therein, and for that purpose, it is preferable to knead and use the antistatic polymer (C).

[Additives] In the resin composition for electromagnetic wave shielding of the present invention, various additives, for example, release agents such as montanic acid wax, polyethylene wax, silicone oil, and the like, as long as the object of the present invention is not impaired, Flame retardants, flame retardant aids, heat stabilizers, UV absorbers, pigments, dyes, transesterification inhibitors (malic acid or sodium hydrogen phosphate) may be added, and thermosetting resins (for example, phenolic resins, Melamine resin, silicone resin, epoxy resin), soft thermoplastic resin (eg, ethylene / vinyl acetate copolymer, epoxy-modified polyolefin) may be added, and fillers (eg, talc, kaolin, wollastonite, clay, Silica, sericite, titanium oxide, glass beads,
Glass balloons, glass flakes, glass powder, glass fibers) may be added.

[Production Method] The resin composition for electromagnetic wave shielding of the present invention is preferably made of thermoplastic polyester (A), fibrous conductive filler (B), antistatic polymer (C), and more preferably The powder (D) can be produced simultaneously or separately by, for example, mixing using a mixer exemplified by a blender, a kneader, a Panbury mixer, a roll, an extruder, and the like, and can be produced by a production method of homogenizing. The components such as the thermoplastic polyester (A) are preferably melt-kneaded using a twin-screw extruder to form a resin composition. The cylinder temperature at this time is preferably about 250 to 270 ° C.

It is also possible to use a method in which each component is dry-blended in advance, melt-kneaded in a heated extruder, homogenized, extruded into a wire, and then cut into a desired length to granulate.

[0062]

The present invention will be described in more detail with reference to the following examples.

The raw materials used in the examples and the evaluation methods are as follows.

(1) Raw Materials The following raw materials were used. Polyether ester block copolymers 1 to 4 Dimethyl terephthalate, dimethyl isophthalate, tetramethylene glycol, ethylene glycol, (modified) polyethylene glycol, tetrabutyl titanate (acid (0.090 mol% based on the components) was charged into the reactor, and the internal temperature was 1
The esterification reaction was performed at 90 ° C. After about 80% of the theoretical amount of methanol was distilled off, the temperature was raised, and the polycondensation reaction was performed while gradually reducing the pressure. After reaching a degree of vacuum of 1 mmHg or less, the reaction was continued at 240 ° C. for 200 minutes. Next, 5% by weight of antioxidant Irganox 1010 was added to polyethylene glycol or modified polyethylene glycol to terminate the reaction. Table 2 shows the composition of the purified polymer. The copolymer used in Examples is the copolymer obtained in Synthesis Example 1. Hereinafter, the copolymer obtained in Synthesis Example 1 is referred to as TRB-EKV including the tables. TRB-E
The surface resistivity of KV is 1 × 10 ¹⁰ Ω.

[0065]

[Table 1]

[0066]

[Table 2]

・ Polybutylene terephthalate (PBT)
Teijin Limited PBT (Melt viscosity 67P at 260 ° C 1000 sec ^-1 )
a · s) PBT (Melt viscosity 240 at 260 ° C. 1000 sec ⁻¹ )
Pa · s) ・ Polycarbonate (PC) PC (manufactured by Teijin Chemicals Ltd., melt viscosity at 315 ° C. 1000 sec ⁻¹ 55 Pa)
・ S) ・ Antistatic polymer SD100 manufactured by Mitsui / Dupont Chemical Co., Ltd. Surface resistivity: 1 × 10 ⁸ Ω Melting point: 92 ° C. ・ Nickel-coated carbon fiber (Ni-CF) (MC) HTA- manufactured by Toho Rayon Co., Ltd. C6-US Volume resistivity: 6 × 10 ⁻⁶ Ωcm ・ Carbon black (CB) Ketjen Black EC600JD manufactured by Lion Corporation ・ Ester exchange inhibitor Sodium hydrogen phosphate dihydrate manufactured by Wako Pure Chemical Industries, Ltd.

(2) Volume resistivity of fibrous conductive filler The volume resistivity was measured according to JIS-R-7601. If measurement by this method is not possible, 100 kg / c
The measurement was performed using an m ² compact.

(3) Surface Resistivity of Antistatic Polymer The surface resistivity was measured using a super insulation meter (SM-TM, manufactured by Toa Denpa Kogyo KK).
10E) (measurement voltage 500 V). In this measurement, the sample was conditioned in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours, and then an environmental temperature of 23 ° C. and a relative humidity of 5% were used.
Performed under 0%.

(4) Melting Point of Antistatic Polymer The melting point was measured by DSC (TA Instruments Japan Co., Ltd.).

(5) Melt viscosity ratio The melt viscosity ratio is defined by the following equation. (Melting viscosity ratio) = (Melting viscosity of antistatic polymer) / (Melting viscosity of thermoplastic polyester) Melting viscosity was measured at a temperature of 260 ° C. and a shear rate of 10.
00 sec ^-1 . For the measurement of the melt viscosity, a rheograph 2002 manufactured by Getfeld, Germany was used.

(6) Shielding property of electromagnetic wave (100 MHz) Using a test piece having a side of 150 mm and a thickness of 3 mm, the shielding property of a magnetic field wave (frequency 100 MHz) was measured by using TR-17301A and R3361A manufactured by Advantest Co., Ltd. Thus, the initial value of the electromagnetic wave (100 MHz) shielding property was set. Further, the test piece was subjected to 100 cycles of heat shock at -40 ° C / 120 ° C, and the shielding properties were measured in the same manner. The shield value was determined as an electromagnetic wave (100 MHz) shield value after 100 cycles of heat shock at -40 ° C / 120 ° C. .

[Examples 1 and 2 and Comparative Examples 1 to 5] After the various raw materials were dry-blended uniformly in the proportions shown in Table 4, the cylinder temperature was adjusted to 180 using a vented twin-screw extruder having a screw diameter of 44 mm. Melting and kneading at ~ 310 ° C, screw rotation speed 160rpm, discharge rate 40kg / h,
The thread discharged from the die was cooled and cut to obtain a molding pellet. In addition, the column of the raw material in Table 4 is a unit by weight.

Next, an injection pressure of 75
A test sample was obtained by injection molding under the conditions of 0 kg / cm ² , an injection speed of 70 cm ³ / sec, a cooling time of 15 seconds, and a total molding cycle of 25 seconds.

Table 3 shows the antistatic agents used. Among these, TRB-EKV is an antistatic polymer which can produce an effect when applied to a PBT, that is, a polymer having good thermal stability and capable of dispersing the antistatic polymer in a network or streak form in the PBT.
It is.

[0076]

[Table 3]

Table 4 shows the results of these evaluations.

[0078]

[Table 4]

As shown in Examples 1 and 2, the electromagnetic wave shielding resin composition of the present invention has an electromagnetic wave shielding property of 40%.
Exceeds dB and the retention rate after heat shock is 90% or more, and the electromagnetic wave shielding property is good.

As shown in Comparative Examples 1, 3 and 4, in the case of a resin composition not satisfying the constitution of the present invention, the retention after heat shock is 70% or less or the extrusion / moldability is poor. Furthermore, in Comparative Examples 2 and 5, the initial electromagnetic wave shielding property is 40 dB or less, and the desired electromagnetic wave shielding property cannot be provided.

[0081]

According to the present invention, it is possible to provide a resin composition for electromagnetic wave shielding which is excellent in electromagnetic wave shielding properties, particularly, initial electromagnetic wave shielding properties, and has little decrease in electromagnetic wave shielding properties due to heat shock. This resin composition for shielding electromagnetic waves can be suitably used for shield connectors for electric vehicles.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J002 BG072 CF071 CF172 CH022 CH042 CL072 DA016 DC006 DM006 FA046 FB076 FD136 GQ00 5E321 AA21 BB31 BB32 BB34 BB44 GG05

Claims (7)

[Claims] (A) An apparent melt viscosity of 10 to 200.
100 parts by weight of Pa · s thermoplastic polyester, (B)
5 to 150 parts by weight of a fibrous conductive filler having a volume resistivity of 1 × 10 ⁻² Ωcm or less and (C) a surface resistivity of 1 × 1
0 to ¹¹ Ω or less, a melting point of 100 ° C. or more, an apparent melt viscosity of 10 to 1000 Pa · s, and a ratio of an apparent melt viscosity to the thermoplastic polyester (A) of 0.01 to 3; An electromagnetic wave shielding resin composition comprising: 2. An antistatic polymer (C) 100% by weight
The electromagnetic wave shielding resin composition according to claim 1, further comprising (D) a conductive powder in an amount of 0.1 to 40% by weight based on the weight of the resin composition. 3. An electromagnetic wave (100) by an Advantest method.
MHz) The initial shield value is 40 dB or more,
The electromagnetic wave shielding resin composition according to claim 1, wherein an electromagnetic wave (100 MHz) shield value after 100 cycles of heat shock at 40 ° C / 120 ° C is 70% or more of an initial value. 4. The resin composition according to claim 1, wherein the thermoplastic polyester (A) is polybutylene terephthalate. 5. The resin composition for electromagnetic wave shielding according to claim 1, wherein the conductive powder (D) is Ketjen black. 6. An antistatic polymer (C) comprising a polyetheresteramide, a polyethylene glycol-based polyester elastomer, a polyethylene glycol methacrylate copolymer, a poly (ethylene oxide / propylene oxide) copolymer and a poly (epichlorohydrin / ethylene oxide) copolymer 4. The resin composition for electromagnetic wave shielding according to claim 1, which is at least one kind of antistatic polymer selected from the group consisting of coalescing. 7. The fibrous conductive filler (B) is at least one kind of fibrous conductive filler selected from the group consisting of nickel-coated carbon fibers, stainless steel fibers and metal whiskers. The resin composition for electromagnetic wave shielding according to any one of the above.