JP2003082168A - Electroconductive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electroconductive resin composition which excels in electroconductivity and has flexibility and, simultaneously, inhibits material deterioration by ultraviolet rays, and the like. SOLUTION: This electroconductive resin composition has a thermoplastic resin, a metallic powder 2 or a metallic fiber, and a low melting point metal 3 such as a lead-free solder, and the thermoplastic resin is a polyolefin based thermoplastic elastomer 1. Compared to the electroconductive resin composition using the conventional thermoplastic elastomer, the weatherability of this composition is improved to inhibit material deterioration by ultraviolet rays, and the like, and thus the electric current application performance can stably be secured for a long period of time. Further, since the modulus of elasticity is improved, the composition and its molded product come to have flexibility, and thus the breakage of an electric current-applied circuit and the molded product by a drop impact and an external load (bending, compression, or the like) can be inhibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrically conductive material having a low resistance value by kneading a thermoplastic resin and a metal to finely disperse the metal in the thermoplastic resin and connecting the dispersed metals to each other. The present invention relates to a conductive resin composition having excellent properties, flexibility, and less discoloration of materials due to ultraviolet rays or the like and less deterioration of strength.

[0002]

2. Description of the Related Art As a conventional conductive resin composition, there is a resin composition composed of a thermoplastic resin, metal fibers, metal powder, and a low melting point metal (JP-A-10-23733).
1, JP-A-10-237315, and JP-A-11-25.
5904 publication).

As shown in FIG. 3, this resin composition is a metal powder which does not melt the thermoplastic resin 11 and the low melting point metal (lead-free solder) 13 under the semi-molten state or the completely molten state of the low melting point metal. It is characterized in that it is kneaded together with 12, the metal powder 12 is finely dispersed in the thermoplastic resin 11 and the metals are connected to each other to obtain a resin composition having a low resistance value.

The electrically conductive resin composition is also characterized in that it can be shaped into an arbitrary shape by an injection molding method, a compression molding method or the like, and that a molded article having excellent electric conductivity can be easily formed.

[0005]

However, in this conductive resin composition, the thermoplastic resin as a constituent component is hard,
Moreover, a large amount of hard components such as metal powder, metal fiber, and lead-free solder are added. Therefore, the molded body obtained from the conductive resin composition is also hard, and when an impact such as a drop or a bending or compressive stress is applied from the outside, the conductive circuit inside the molded body or the molded body itself breaks and the predetermined However, there is a problem that the conductive function of is not obtained. As a means for solving this problem, JP-A-2000-357413 and JP-A-2001-2001 which give flexibility to a conductive resin composition.
No. 72775 and Japanese Patent Laid-Open No. 2001-72774. These compositions are characterized by having an extremely high degree of electrical conductivity and also having excellent mechanical strength.

However, when the conductive resin composition having this flexibility is used in a portion directly irradiated with sunlight or lamp light, or in the vicinity thereof, the thermoplastic elastomer as a base component is deteriorated by ultraviolet rays. However, it may decompose, causing discoloration and strength deterioration, and it may not be possible to obtain sufficient electrical conductivity.

Therefore, an object of the present invention is to solve the above-mentioned problems, in which the conductive resin composition has excellent electric conductivity and flexibility, and the conductive material inside the molded article is electrically conductive due to drop or external stress load. It is an object of the present invention to provide a conductive resin composition in which a circuit or a molded body itself is not destroyed, and material deterioration due to ultraviolet rays or the like is suppressed, and a current-carrying function can be stably ensured for a long period of time.

[0008]

In order to solve the above problems, the conductive resin composition according to claim 1 of the present invention comprises a thermoplastic resin, metal powder or metal fibers, a low melting point metal such as lead-free solder. In the conductive resin composition provided, the thermoplastic resin is a polyolefin-based thermoplastic elastomer.

As described above, since the thermoplastic resin constituting the conductive resin composition is a polyolefin-based thermoplastic elastomer, the weather resistance is higher than that of a conductive resin composition using a general thermoplastic elastomer. As a result, the deterioration of the material due to ultraviolet rays can be suppressed, and a stable energizing function can be secured for a long period of time. Further, since the elastic modulus is improved, the composition and the molded product have flexibility, and it is possible to suppress damage to the energized circuit and the molded product due to a drop impact or external load (bending, compression, etc.).

The conductive resin composition according to claim 2 is the same as the conductive resin composition according to claim 1, wherein the polyolefin thermoplastic elastomer has JIS-A hardness of 20 to 6
It is 0. Since the JIS-A hardness of the thermoplastic polyolefin-based elastomer is 20 to 60,
It is possible to greatly improve the elastic modulus of the conductive resin composition. Further, the range of elastic modulus of the conductive resin composition can be set in a wide range, and weathering discoloration resistance by ultraviolet rays can be suppressed.

The conductive resin composition according to claim 3 is the same as the conductive resin composition according to claim 1, wherein the melt float rate (MR) of the thermoplastic polyolefin-based elastomer is the same.
F) is 2 to 25 g / 10 min. As described above, since the melt float rate (MRF) of the thermoplastic polyolefin-based elastomer is 2 to 25 g / 10 min, the energizing circuit is formed in the composition. In addition, a low-melting point metal appears on the surface of the molded body without causing defective molding, and the low-melting point metal and the metal powder are regularly dispersed in the resin composition without agglomeration, and have electrical conductivity comparable to that of metal. It is possible to provide a resin composition.

The conductive resin composition according to claim 4 is the conductive resin composition according to claim 1, wherein the conductive resin composition has a volume specific resistance value of 1.0 × 10 ⁻⁴ Ω · cm or less. is there. As described above, since the volume resistivity of the conductive resin composition is 1.0 × 10 ⁻⁴ Ω · cm or less, resistance heating occurs when the molded body made of the conductive resin composition is energized. It becomes possible to use it as a highly reliable electric circuit.

The conductive resin composition according to claim 5 is the conductive resin composition according to claim 4, wherein the conductive resin composition has a JIS-A hardness of 30 to 80. As described above, the JIS-A hardness of the conductive resin composition is 30 to 80.
Therefore, the conductive resin composition is excellent in electric conductivity and has flexibility, and the conductive circuit inside the molded body or the molded body itself is not destroyed by dropping or external stress load.

The conductive resin composition according to claim 6 is the conductive resin composition according to claim 1, wherein the total weight of the metal powder or metal fiber and the low melting point metal is 35 vol% or more and 70 vol% or less. . In this way, the total weight of the metal powder or metal fiber and the low melting point metal is 35 vol%.
As described above, since it is 70 vol% or less, the amount of the metal component contained in the conductive resin composition becomes appropriate, and a conductive resin composition satisfying both flexibility and volume resistance value is obtained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic structural view of a conductive resin composition according to an embodiment of the present invention.

As shown in FIG. 1, this conductive resin composition is composed of at least a polyolefin thermoplastic elastomer 1, metal powder 2 or metal fibers, and a low melting point metal 3 such as lead-free solder. It is composed of melt-kneaded in advance.

Table 1 shows the constitutions of the conductive resin compositions (Examples) produced according to this embodiment and Comparative Examples.

[0018]

[Table 1]

The base resin of the example is manufactured by olefin thermoplastic elastomer Thermolan 3652N Mitsubishi Chemical Co., Ltd., and the base resin of Comparative Example 1 is manufactured by polyester thermoplastic elastomer Primalloy A1500N Mitsubishi Chemical Co., Ltd. The base resin is a styrene thermoplastic elastomer Lavalon SJ4400N manufactured by Mitsubishi Chemical Co., Ltd., and the amount thereof is 45 vol% each. The metal powders of Examples and Comparative Examples 1 and 2 are both copper powder FCC-115 manufactured by Fukuda Metal Foil & Powder Co., Ltd.
The amounts are 40 vol% each. Example and Comparative Example 1,
The low melting point metals of 2 are both lead-free solder Sn-Cu
-Ni-AtW-150 manufactured by Fukuda Metal Foil & Powder Co., Ltd., and the amount of each is 15 vol%.

As shown in Table 1, by using a thermoplastic polyolefin elastomer as the base resin constituting the conductive resin composition, the elastic modulus of the conductive resin composition can be improved and the weather resistance can be improved. Can be improved.

In the weather resistance test method, the molded body is placed in a test tank kept at 60 ° C., a mercury lamp is continuously irradiated, and the molded body is left for 60 days. The molded product before and after the test was measured and calculated by a color computer (SM-7, manufactured by Suga Test Instruments Co., Ltd.).

The material of the metal powder or metal fiber is copper (C
u), nickel (Ni), iron (Fe), aluminum (Al), and the like, and alloys thereof are not particularly limited.

The low melting point metal is tin (Sn), bismuth (Bi), zinc (Zn), most preferably Sn-C.
Examples thereof include low melting point alloys such as u and Sn—Zn, but are not particularly limited.

The volume of the conductive resin composition is
The resistivity is a conductive material (metal powder or metal fiber, low melting point)
It can be changed depending on the mixing ratio of point metal). Our examination result
Then, thermoplastic elastomer is 45 vol%, metal powder
Or 40 vol% of metal fiber and 15 vol% of low melting point metal
When mixed in proportion, the volume resistivity value is 1.0 x 10 ^-Four
Stable production of conductive resin composition of Ω · cm or less is possible
It is known that it is, but especially limited to this blending ratio
It is not something that will be done.

Any known amount of known ultraviolet absorbers, light stabilizers, antistatic agents, heat stabilizers, antioxidants, flame retardants, lubricants, etc. may be added to the conductive resin composition. There are no problems and the properties can be improved by adding these materials to the composition.

As a manufacturing device for melting and kneading the conductive resin composition, a general kneading device for resins, rubbers and ceramics can be used, but the following devices are typical examples.

<Specific Kneading Equipment and Kneading Conditions Used in the Embodiment of the Present Invention> Kneading equipment: Pressurized kneader (DS3-10, Moriyama Co., Ltd.) Kneading conditions: a) Mixing tank temperature: 220 ° C. b) Rotor rotation speed: 48 rpm (both two) c) Kneading time: 15 min This kneading device puts materials into a mixing tank set to a predetermined temperature in advance, and has two rotors installed in the mixing tank. The material introduced by rotating at a predetermined number of revolutions is melted and plasticized by heat and pressure.
By using this kneading device, the thermoplastic elastomer having extremely different specific gravity, the metal powder or metal fiber, and the low melting point metal were dispersed.

An example of the above-mentioned kneading conditions will be shown. Under these kneading conditions, only the polyolefin-based thermoplastic elastomer and the low melting point metal are melted.

The kneaded material melted and kneaded by the kneading device is generally taken out in a lump form. In the molding step of melting the lump composition again and shaping it into an arbitrary shape, a granular composition called pellet was produced in order to more stably produce a molded product (granulation step) .

The following apparatus can be used as the apparatus used for granulation. This granulator pushes forward while melting the composition by means of a biaxial taper screw set at a predetermined temperature. The extruded composition is discharged from a die (φ3 mm, 12 pieces) provided at the tip, cut by a metal cutter, cooled, and processed into pellets having a predetermined shape.

<Specific Granulating Device Used in Embodiment of the Present Invention and Granulating Conditions> Granulating device: Twin-screw single-screw extruder (2TR-50, Moriyama Co., Ltd.) Granulating condition: a ) Hopper temperature: 170 ° C. b) Screw temperature: 170 ° C. c) Die temperature: 170 ° C. d) Screw rotation speed: 20 rpm (both two) The conductive resin composition was molded into an arbitrary shape. Injection molding method, compression molding method, etc. are possible as a method of molding into an arbitrary shape, but the shape can be reproduced more accurately,
The injection molding method is generally used because of its high productivity. In the embodiment of the present invention, the conductive resin composition is molded into a predetermined shape by an injection molding method.

<Specific Injection Molding Equipment Used in the Embodiment of the Present Invention> Injection Molding Equipment: Injection Molding Machine (FE120, Nissei Plastic Industry Co., Ltd.) In addition, the shape molded by the above injection molding machine is In the embodiment of the present invention, the conductive resin composition was molded into a flat plate, and the volume resistivity value was measured.

<Specific Shape of Molded Product Used in the Embodiment of the Present Invention> Molded product shape: length 80 mm, width 50 m, wall thickness 2 mm The conductive resin composition pellets obtained in step 1 were injection-molded to form flat plates, and the volume resistivity of each molded product and JI
The SA hardness was measured.

The method for measuring the volume resistivity is as follows:
In accordance with the Four Short Needle Method stipulated in JIS-K-7194,
A resistivity meter (Loresta AP MCP-T400,
Mitsubishi Yuka Co., Ltd. was used.

The JIS-A hardness is JIS-K-6.
It was carried out in accordance with the durometer hardness test method defined in No. 301.

A second embodiment of the present invention will be described.

In this embodiment, in the first embodiment, JI of the thermoplastic polyolefin elastomer is used.
The S-A hardness is 20-60. Table 2 shows the configurations of the conductive resin composition (Example) manufactured according to this embodiment and the comparative example.

[0038]

[Table 2]

The base resin of the example is an olefin-based thermoplastic elastomer Thermolan 3551N manufactured by Mitsubishi Chemical Corporation, JIS-A hardness is 55, and the base resin of Comparative Example 1 is an olefin-based thermoplastic elastomer Thermolan 3652N Mitsubishi Chemical (stock). ), JIS-A hardness 6
5, the base resin of Comparative Example 2 is an olefin-based thermoplastic elastomer Thermolan 3981N Mitsubishi Chemical Corporation
Made, JIS-A hardness is 93, the amount is 45v each
ol%. The metal powder and low melting point metal of the example and the comparative examples 1 and 2 are the same as those in the first embodiment.

As shown in Table 2, JIS-A hardness is 20.
By using the polyolefin thermoplastic elastomer of up to 60, the elastic modulus of the conductive resin composition can be significantly improved.

Further, even if the molded product is dropped from a position 1 m above the floor surface, the molded product is not broken and the volume resistivity value can be maintained at the same value as before the test.

A third embodiment of the present invention will be described.

In this embodiment, the melt float rate (MRF) of the thermoplastic polyolefin-based elastomer is 2 to 25 g / 10 min in the first embodiment.
Is. Table 3 shows the configurations of the conductive resin composition (Example) manufactured according to this embodiment and Comparative Example.

[0044]

[Table 3]

The base resin of Example 1 is an olefinic thermoplastic elastomer Thermolan 3551N manufactured by Mitsubishi Chemical Corporation, JIS-A hardness is 55, and MRF is 7.0 g.
/ 10 min, the base resin of Example 2 is an olefinic thermoplastic elastomer Thermolan 3981N manufactured by Mitsubishi Chemical Corporation, JIS-A hardness is 93, MRF is 15 g.
/ 10 min, the base resin of the comparative example is an olefin-based thermoplastic elastomer Thermolan 3702N manufactured by Mitsubishi Chemical Corporation, JIS-A hardness is 80, MRF is 50 g / 1.
0 min and the amount is 45 vol% each. The metal powders and low melting point metals of Examples 1 and 2 and the comparative example are the same as those in the first embodiment.

As shown in Table 3, when the MFR of the thermoplastic elastomer is 2 to 25 g / 10 min, the energizing circuit as shown in FIG. 1 is formed in the composition. But MF
If R exceeds the above range, as shown in FIG.
The metal component aggregates without forming an energizing circuit in the composition,
It is impossible to obtain sufficient electrical conductivity.

A fourth embodiment of the present invention will be described.

In this embodiment, the volume specific resistance value of the conductive resin composition in the first embodiment is 1.0 ×.
It is 10 ⁻⁴ Ω · cm or less. The JIS-A hardness of the conductive resin composition is 30-80. In addition, the total weight of the metal powder or metal fiber and the low melting point metal is 35 vol.
% Or more and 70 vol% or less. Table 4 shows the configurations of the conductive resin composition (Example) manufactured according to this embodiment and the comparative example.

[0049]

[Table 4]

The base resins of Examples 1, 2 and 3 and Comparative Examples 1 and 2 are olefinic thermoplastic elastomer Thermolan 3551N manufactured by Mitsubishi Chemical Corporation, JIS-A hardness is 55, MRF is 7.0 g / 10 min. is there. The types of metal powders and low melting point metals of Examples 1, 2 and 3 and Comparative Examples 1 and 2 are the same as those in the first embodiment. The amount of the base resin in Example 1 was 45 vol% and the amount of the metal powder was 40.
vol%, the amount of the low melting point metal is 15 vol%, the amount of the base resin of Example 2 is 50 vol%, and the amount of the metal powder is 30%.
vol%, the amount of the low melting point metal is 20 vol%, the amount of the base resin of Example 3 is 70 vol%, and the amount of the metal powder is 15.
vol%, the amount of low melting point metal is 15 vol%, the amount of base resin of Comparative Example 1 is 80 vol%, and the amount of metal powder is 10 vol%.
vol%, the amount of low melting point metal is 10 vol%, the amount of base resin of Comparative Example 2 is 30 vol%, and the amount of metal powder is 55
The amount of vol% and low melting point metal is 15 vol%.

As shown in Table 4, when the amount of the metal component (the total amount of the low melting point metal, the metal powder or the metal fiber) contained in the conductive resin composition is increased, the volume resistance value decreases, but JIS- A hardness increases and becomes hard. On the other hand, when the amount of the metal component is reduced, the JIS-A hardness becomes small and becomes soft, but the volume resistance value becomes large. Therefore, in order to obtain a conductive resin composition that satisfies both flexibility and volume resistance, an appropriate content of components is required.

[0052]

According to the conductive resin composition of claim 1 of the present invention, since the thermoplastic resin constituting the conductive resin composition is a polyolefin thermoplastic elastomer, a general thermoplastic elastomer is used. The weather resistance is improved as compared with the conductive resin composition using, and the deterioration of the material due to ultraviolet rays or the like can be suppressed, and a stable energizing function can be secured for a long period of time. Further, since the elastic modulus is improved, the composition and the molded product have flexibility, and it is possible to suppress damage to the energized circuit and the molded product due to a drop impact or external load (bending, compression, etc.). Further, the wear resistance of the surface of the molded product is improved.

According to the second aspect, since the JIS-A hardness of the thermoplastic polyolefin-based elastomer is 20 to 60, the elastic modulus of the conductive resin composition can be significantly improved. Further, the range of elastic modulus of the conductive resin composition can be set in a wide range, and weathering discoloration resistance by ultraviolet rays can be suppressed.

In Claim 3, the melt float rate (MRF) of the thermoplastic polyolefin-based elastomer is 2 to 2.
Since it is 25 g / 10 min, a current-carrying circuit is formed in the composition. In addition, a low-melting point metal appears on the surface of the molded body without causing defective molding, and the low-melting point metal and the metal powder are regularly dispersed in the resin composition without agglomeration, and have electrical conductivity comparable to that of metal. It is possible to provide a resin composition.

According to the fourth aspect, the volume resistivity of the conductive resin composition is 1.0 × 10 ⁻⁴ Ω · cm or less, so that when a molded body made of the conductive resin composition is energized. ,
It can be used as a highly reliable electric circuit without resistance heat generation.

According to the fifth aspect, the JIS of the conductive resin composition is used.
Since the -A hardness is 30 to 80, the conductive resin composition has excellent electric conductivity and flexibility, and the conductive circuit inside the molded body or the molded body itself is destroyed by dropping or external stress load. There is no such thing.

In the sixth aspect, the total weight of the metal powder or metal fiber and the low melting point metal is 35 vol% or more, 70 v or more.
Since it is ol% or less, the amount of the metal component contained in the conductive resin composition becomes appropriate, and a conductive resin composition satisfying both flexibility and volume resistance value is obtained.

[Brief description of drawings]

FIG. 1 is a structural schematic view of a conductive resin composition according to an embodiment of the present invention.

FIG. 2 is a structural schematic diagram showing a state in which a current-carrying circuit is not formed in the composition.

FIG. 3 is a schematic structural view of a conductive resin composition of a conventional example.

[Explanation of symbols]

1 Polyolefin-based thermoplastic elastomer 2 Metal powder 3 Low melting point metal

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4J002 AA011 BB001 DA076 DA077                       DA086 DA087 DA096 DA107                       DA117 FA046 FD116 GQ02                 5G301 DA02 DA06 DA43 DD10

Claims (6)

[Claims] 1. A conductive resin composition comprising a thermoplastic resin, metal powder or metal fiber, a low melting point metal such as lead-free solder, wherein the thermoplastic resin is a polyolefin-based thermoplastic elastomer. A characteristic conductive resin composition. 2. The conductive resin composition according to claim 1, wherein the thermoplastic polyolefin elastomer has a JIS-A hardness of 20 to 60. 3. A thermoplastic elastomer having a melt float rate (MRF) of 2 to 25 g / 10.
The conductive resin composition according to claim 1, which is min. 4. The conductive resin composition according to claim 1, wherein the conductive resin composition has a volume resistivity value of 1.0 × 10 ⁻⁴ Ω · cm or less. 5. The JIS-A hardness of the conductive resin composition is
The conductive resin composition according to claim 4, which is 30 to 80. 6. The conductive resin composition according to claim 1, wherein the total weight of the metal powder or metal fiber and the low melting point metal is 35 vol% or more and 70 vol% or less.