JP2001072775A - Conductive resin molding or sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive resin molding or sheet excellent in electric conductivity, moldability, and mechanical strengths by mixing a blend of a thermoplastic resin and a thermoplastic elastomer with a low-m.p. metal having a specified m.p. and a metal powder. SOLUTION: A thermoplastic resin is blended with a thermoplastic elastomer to give a blend having a durometer A hardness of 35 or higher and a durometer D hardness of 60 or lower. This blend in an amount of 20-80 vol.% is mixed with a low-m.p. metal having an m.p. of 300 deg.C or lower and a metal powder having an average particle size of 1-50 μm. The ratio of the amount of the metal powder to the sum of amounts of the low-m.p. metal and the metal powder is preferably 10-30 vol.%. The conductive resin molding or sheet is prepared by kneading the above-prepared mixture at a certain temperature with a kneading machine such as a kneader or a twin-screw extruder, granulating the kneaded mixture, and molding the resultant granules with a metal mold having a desired shape by a conventional molding method such as injection molding, transfer molding or press molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive resin molded article or sheet having extremely high conductivity and excellent moldability and mechanical strength.

[0002]

2. Description of the Related Art Conventionally, as a conductive resin molded article or sheet obtained by imparting conductivity to a molded article made of various resins, a molded article or sheet formed by using a composite material obtained by dispersing and mixing a conductive filler in a synthetic resin has been used. Are known. Metal-based, carbon-based, etc. are used as conductive fillers, but in order to impart a high degree of conductivity, the amount of conductive fillers must be increased significantly, resulting in deterioration of moldability and , It becomes brittle and the mechanical strength decreases, so the amount added is limited,
The conductivity of the resulting molded product or sheet is also 1 volume resistivity.
0 ^-1 Ω · cm was the limit.

[0003]

Accordingly, there has been a demand for a conductive resin molded article or sheet having an extremely high conductivity and excellent moldability and mechanical strength.

[0004]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention. That is, the gist of the present invention is that (a) a thermoplastic resin and (b)
The conductive resin molded article or sheet is obtained by mixing a thermoplastic elastomer blend as a substrate, (c) a low melting point metal having a melting point of 300 ° C. or lower, and (d) a metal powder.

[0005] Preferred embodiments of the present invention include the following. A blend of (a) a thermoplastic resin and (b) a thermoplastic elastomer is used as a binder for the entire molded article or sheet.
(C) and (d)
The ratio of the metal powder (d) in the metal component obtained by combining
2. The method according to claim 1, wherein the amount is in the range of 30% by volume.
The conductive resin molded article or sheet according to the above. The hardness of the blend of (a) the thermoplastic resin and (b) the thermoplastic elastomer is 35 or more in durometer A hardness and 6 in durometer D hardness.
The conductive resin molded article or sheet described above, which is in a range of 0 or less. The low melting point metal of the component (c) is Pb /
Sn, Pb / Sn / Bi, Pb / Sn / Ag, Pb / A
g, Sn / Ag, Sn / Bi, Sn / Cu, Sn / Zn
The conductive resin molded article or sheet described above, comprising a low melting point alloy selected from the group consisting of: (D) The conductive resin molded article or sheet described above, wherein the metal powder of the component is made of Cu, Ni, Al, Cr, or an alloy powder thereof, and has an average particle diameter in the range of 1 to 50 μm.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The conductive resin molded article or sheet according to the present invention is composed of (a) a thermoplastic resin, (b) a thermoplastic elastomer,
It is characterized by comprising a mixture of (c) a low melting point metal having a melting point of 300 ° C. or lower and (d) a metal powder (hereinafter, referred to as “mixture”). By using a specific combination of a thermoplastic resin, a thermoplastic elastomer and a metal component for imparting conductivity, it has been found that a very high degree of conductivity and other properties can be imparted in a well-balanced manner, In the mixed material, a blend of (a) a thermoplastic resin and (b) a thermoplastic elastomer is used in an amount of 20 to 8 of the total composition.
It is preferably contained in an amount of 0% by volume, preferably 40 to 60% by volume. When the content of the resin blend component exceeds 80% by volume, conductivity tends to hardly develop, and when the content is less than 20% by volume, the fluidity is reduced and moldability tends to be poor.

The hardness of the blend of (a) the thermoplastic resin and (b) the thermoplastic elastomer is 3 in durometer A hardness.
It is preferable that the hardness is 5 or more and the durometer D hardness is 60 or less, and it is preferable that the durometer A hardness is 50 or more and the durometer D hardness is 50 or less. If the hardness of the blend is less than 35 in durometer A hardness, it is too soft and molding is difficult, and if the durometer D hardness is 60 or more, the effect of brittleness modification tends to be lost. It is also preferable to add an interfacial adhesive such as an acid-modified polyolefin in order to improve the adhesive strength between the resin blend and the low melting point metal.
The metal powder (d) acts as a dispersing aid for the low melting point metal, and the proportion of the metal powder (d) in the metal component is preferably in the range of 10 to 30% by volume, preferably 15 to 25% by volume. . If the content is less than 10% by volume, the dispersion state becomes poor,
On the other hand, if it exceeds 30% by volume, the fluidity tends to decrease and the material tends to become brittle, and the conductivity tends to decrease.

Various materials such as polyolefin resin, ABS resin, polyester resin, and polycarbonate resin can be used as the thermoplastic resin (a) used for the mixture material. (B) As the thermoplastic elastomer, (a) the thermoplastic resin Any type can be used as long as it is compatible with olefins, styrenes, PVCs, urethanes, esters and amides. For example,
When polypropylene (PP) is used as the thermoplastic resin (a), it is preferable to use a polyolefin-based elastomer as the thermoplastic elastomer (b).

Various metals can be used as the low melting point metal having a melting point of 300 ° C. or less in (c). The melting point can be measured by the differential scanning calorimetry (DSC).
The measurement may be performed according to C), and there is a problem that a metal having a melting point exceeding 300 ° C. has poor moldability. Specifically, P
b / Sn, Pb / Sn / Bi, Pb / Sn / Ag, Pb
/ Ag, Sn / Ag, Sn / Bi, Sn / Cu, Sn /
A low melting point alloy selected from Zn-based can be suitably used.
The metal powder of the component (d) serves as a dispersing aid for the low melting point metal, and Cu, Ni, Al, Cr and alloy powders thereof can be suitably used, and the average particle size is 1 to 50 μm.
Are preferred. The average particle diameter is a number average particle diameter obtained by photographing a sample with a transmission electron microscope and obtaining the photograph. When the average particle size is less than 1 μm, handling during mixing is difficult, and when the average particle size exceeds 50 μm, the dispersibility tends to decrease.

In the method for producing a conductive resin molded product or sheet of the present invention, the components of the above-mentioned mixed material are kneaded at a predetermined temperature by a kneader such as a kneader or a twin-screw extruder. A method using granules is preferred. In kneading, (c) a temperature at which the low-melting-point metal is in a semi-molten state is preferred, and an appropriate metal composition is selected according to the melting temperature of the resin blend serving as a matrix, and the low-melting-point metal and copper powder serving as a dispersing aid are selected. It is necessary to appropriately select the addition ratio of nickel powder and the like. The granulated product obtained by the above method is formed into a molded product by a normal molding method such as an injection molding method, a transfer molding method, and a press molding method using a mold having a shape corresponding to a purpose of use. be able to. Further, it can be formed into a sheet by a T-die extruder or the like.

As described above, the conductive molded article or sheet of the present invention has an extremely high conductivity because the blend of a thermoplastic resin and a thermoplastic elastomer contains a low melting point metal. In, because of the flexibility of the thermoplastic elastomer, does not become brittle, has excellent moldability and mechanical strength, conductive partition, conductive member, antistatic material,
It can be applied to a wide range of fields such as electromagnetic wave shielding materials, electrodes, connectors, sensors, and heating elements.

[0012]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. (Example 1) PP as a thermoplastic resin of a resin blend
(MS640 / Tokuyama), a polyolefin-based elastomer (Santoprene 201) as a thermoplastic elastomer
-55 / AES Japan) was used at 50:50. The hardness of the blend was 40 in Durometer D hardness.
In addition, an acid-modified polyolefin ("Adtex ER320P" manufactured by Nippon Polyolefin Co., Ltd.) is used as an interfacial adhesion modifier, and a lead-free solder (Sn-4Cu-2Ni melting point solid-phase line 225 ° C.-liquidus line) is used as a low-melting metal. 480 ° C.), and copper powder having an average particle size of 10 μm was used as the metal powder. Each raw material powder is physically mixed in advance (resin blend 40% by volume, acid-modified polyolefin 10% by volume, low melting point metal 45% by volume, metal powder 5% by volume), twin screw extruder ("2D25-S" Toyo Seiki ( After melting and kneading using a resin, low-melting-point metal-containing resin pellets were prepared.

The extrusion conditions are as follows. Cylinder temperature: 200 ° C Screw rotation speed: 20r. p. m. Thereafter, the injection mold (1) in which the female mold and the male mold are opposed to each other.
The low-melting-point metal-containing resin pellets were injection-molded in a rectangular cavity having a size of 10 mm × 75 mm and a thickness of 1 mm) under the following conditions. Mold temperature: 40 ° C Cylinder temperature: 200 ° C Screw rotation speed: 50r. p. m. Injection rate: 60 cm ³ / sec Injection pressure: 80 Mpa Back pressure: 2 Mpa Holding time: 40 seconds

After cooling, the mold was removed to obtain the desired molded product.
The characteristics of the obtained molded product were as follows. Charpy impact value: not destroyed Volume specific resistance value: 4.14 × 10 ⁻⁴ Ω · cm The impact test conforms to JIS K7111 (Charpy-flat width notched test piece width 10 mm, distance between fulcrums 20 mm, test speed 0. 5mm / min) Hardness is JIS
Compliant with K7215

Comparative Example 1 In place of the resin blend of Example 1, PP alone (MS640) which is a normal thermoplastic resin was used.
/ Tokuyama), and a molded article was obtained in the same manner as in Example 1, and the molded article similarly obtained was evaluated. The characteristics of this molded product were as follows. Charpy impact value: 5.44 kJ / m ² Volume resistivity: 5.04 × 10 ⁻⁴ Ω · cm

Comparison between Example 1 and Comparative Example 1 shows that the molded product of Example 1 of the present invention has improved fragility while maintaining a high volume resistivity, as is apparent from the impact characteristics. You can see that.

Example 2 PP (MS640 / Tokuyama) was used as the thermoplastic resin of the resin blend, and a polyolefin-based elastomer (Santoprene 201-55 / AES Japan) was used at 50:50 as the thermoplastic elastomer. The hardness of the blend is 4 in Durometer D hardness.
It became 0. In addition, an acid-modified polyolefin ("Adtex ER320P" manufactured by Nippon Polyolefin Co., Ltd.) is used as an interfacial adhesion modifier, and a lead-free solder (Sn-4Cu-2Ni melting point solidus 225 ° C.) is used as a low melting point metal.
(Liquidus line 480 ° C.), and copper powder having an average particle size of 10 μm was used as the metal powder. Physically mix each raw material powder in advance (resin blend 40% by volume, acid-modified polyolefin 10% by volume, low melting point metal 45% by volume, metal powder 5% by volume), 2
After melt-kneading using a screw extruder (“2D25-S” manufactured by Toyo Seiki Co., Ltd.), a low melting point metal-containing resin pellet was prepared. Extrusion conditions are as follows. Cylinder temperature: 200 ° C Screw rotation speed: 40r. p. m. Thereafter, a sheet having a thickness of 1 mm was formed by a T-die extruder under the following conditions. Cylinder temperature: 200 ° C Cap temperature: 200 ° C Screw rotation speed: 50r. p. m. A sheet that did not break when bent at 180 degrees was easily obtained.

(Comparative Example 2) A trial production was performed in the same manner as in Example 2 except that PP (MS640 / Tokuyama), which is a normal thermoplastic resin, was used instead of the resin blend of Example 2. The molding conditions at the time of extruding the T-die were variously changed, but the extrudate was brittle and could not be formed into a sheet.

[0019]

As described above, the conductive resin molded product or sheet of the present invention contains a low melting point metal in a thermoplastic resin / thermoplastic elastomer blend.
It has an extremely high level of conductivity, excellent moldability and mechanical strength, and can be applied to a wide range of fields such as conductive partitions, conductive members, antistatic materials, electromagnetic wave shielding materials, electrodes, connectors, sensors, and heating elements. It is possible.

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Claims (5)

[Claims] 1. A blend of (a) a thermoplastic resin and (b) a thermoplastic elastomer as a substrate, and (c) a low-melting metal having a melting point of 300 ° C. or less, and (d) a metal powder. Conductive resin molded product or sheet. 2. A blend of (a) a thermoplastic resin and (b) a thermoplastic elastomer contains 20% of the entire molded article or sheet.
(C) and (d)
The ratio of the metal powder (d) in the metal component obtained by combining
The conductive resin molded product or sheet according to claim 1, wherein the content is in a range of 30% by volume. 3. The hardness of a blend of (a) a thermoplastic resin and (b) a thermoplastic elastomer, wherein the durometer A hardness is 35 or more and the durometer D hardness is 60 or less. 3. The conductive resin molded product or sheet according to any one of claims 1 to 2. 4. The low melting point metal of component (c) is Pb / S
n, Pb / Sn / Bi, Pb / Sn / Ag, Pb / A
g, Sn / Ag, Sn / Bi, Sn / Cu, Sn / Zn
The conductive resin molded article or sheet according to claim 1, wherein the conductive resin molded article or sheet is made of a low melting point alloy selected from a series. 5. The metal powder of component (d) is Cu, Ni, A
2. The powder of claim 1, wherein said powder is made of l, Cr or an alloy powder thereof, and has an average particle diameter in the range of 1 to 50 μm.
5. A conductive resin molded product or sheet according to any one of items 4 to 4.