JP5040107B2 - Method for producing molded product made of conductive thermoplastic resin - Google Patents

Description

  The present invention relates to a method for producing a molded product of a conductive thermoplastic resin.

  Conductive resin compositions obtained by adding various conductive fillers to thermoplastic resins are used in various fields. As such a conductive resin composition, a resin composition in which carbon fiber is blended with a polycarbonate resin and a methacrylate resin is known (see Patent Document 1).

JP 2002-265768 A

  However, the molded product obtained using the conventional conductive resin composition has insufficient conductivity. When used in a particularly severe environment, for example, when the use under a low temperature atmosphere and the use under a high temperature atmosphere are repeated, the conductivity is often impaired.

  An object of the present invention is to provide a method for producing a molded product made of a conductive thermoplastic resin having excellent conductivity.

That is, the present invention relates to a method for producing a molded article made of a conductive thermoplastic resin, comprising a conductive fiber (A), a rod-shaped low melting point metal (B) having a melting point lower than that of the conductive fiber (A), and a polypropylene resin. 5 to 60% by weight of a polypropylene resin- coated conductive composition (E) satisfying the following requirements (1) and (2), and a thermoplastic resin (D) 95 satisfying the following requirement (3): This is a method for producing a molded part made of a conductive thermoplastic resin, which is mixed with ˜40% by weight and injection molded.
(1) The conductive fiber (A) and the low melting point metal (B) are coated with the polypropylene resin (C). (2) The weight of the thermoplastic resin-coated conductive composition (E) is 100%. When the conductive fiber (A) content is 35 to 95% by weight, the low melting point metal (B) content is 4 to 45% by weight, and the polypropylene resin (C) content is 1 to 20% by weight. (3) Of the peaks observed in the range of 50 to 300 ° C. in the endothermic curve obtained by measuring the polypropylene resin (C) with a differential scanning calorimeter (DSC) at a temperature rising rate of 10 ° C./min. In an endothermic curve obtained by measuring a peak (Pc) indicating the maximum temperature and a thermoplastic resin (D) using a differential scanning calorimeter (DSC) at a temperature rising rate of 10 ° C./min, 50 to 300 ° C. The highest temperature among the peaks observed in the range Peak (Pd) indicating a, but with Pc + 20 ≦ Pd (℃)

  According to the method for producing a molded product of a conductive thermoplastic resin of the present invention, a molded product of a thermoplastic resin having excellent conductivity can be obtained. The molded product made of the conductive thermoplastic resin obtained by the present invention has excellent conductivity even when used in particularly severe environments, for example, when used in a low temperature atmosphere and repeated use in a high temperature atmosphere. Sex can be maintained.

  Hereinafter, the present invention will be described in detail. In the present invention, a thermoplastic resin coating in which a conductive fiber (A) and a rod-shaped low melting point metal (B) having a melting point lower than that of the conductive fiber (A) are coated with a thermoplastic resin (C). A conductive composition (E) is used.

  The conductive fiber (A) in the present invention is preferably a long metal fiber. Examples of the fiber types used for the conductive fibers include stainless steel, brass, copper, aluminum, iron, gold, silver, nickel, titanium, tin, zinc, magnesium, platinum, beryllium, alloys of these metal types, these Examples thereof include compounds of metal species and phosphorus. Among these metal species, brass, copper, aluminum, iron, gold, silver, nickel, and titanium are preferably used, and copper is more preferably used. The metal fiber can be produced by a method such as a wire drawing method, a melt spinning method, a coil material cutting method, or a wire cutting method using the above metal species as a raw material. The metal fiber may be surface-treated with a coupling agent such as a silane coupling agent or a titanate coupling agent or a surface treatment agent such as a triazine thiol compound.

  In addition, as the conductive fiber (A) used in the present invention, a conductive organic fiber or inorganic fiber such as a carbon fiber, a metal layer provided on the surface of an organic fiber such as a polyester fiber or a polyamide fiber, And those obtained by providing a metal layer on the surface of an inorganic fiber such as glass fiber. The method for applying the metal layer to the organic fiber or the inorganic fiber may be appropriately selected according to the type of the fiber, and examples thereof include vapor deposition, plating, sputtering, ion plating, and the like. The conductive fiber (A) in the present invention is preferably a copper fiber. The conductive fiber (A) used in the present invention preferably has a volume resistance of 50 μΩcm or less from the viewpoint of conductivity.

  The content of the conductive fiber (A) in the thermoplastic resin-coated conductive composition (E) is 35 to 95% by weight when the weight of the thermoplastic resin-coated conductive composition (E) is 100%. More preferably, it is 50 to 80% by weight. When the content of the conductive fiber (A) is too small, the conductivity tends to be insufficient. When the content is too large, poor dispersion of the conductive fiber (A) is likely to occur, and the thermoplastic resin-coated conductive composition. There exists a tendency for the electroconductivity of the molded article obtained using this to fall.

  The cross-sectional shape of the conductive fiber (A) is not particularly limited, but is preferably substantially circular. The fiber diameter of the conductive fiber (A) is preferably 5 to 100 μm, more preferably 10 to 80 μm, and still more preferably 40 to 60 μm. Here, the fiber diameter of the conductive fiber (A) usually refers to the fiber diameter when converted to a circle having the same cross-sectional area. When the fiber diameter is in the range of 5 to 100 μm, contact between the conductive fibers occurs efficiently, so that sufficient conductivity can be obtained with a small content, which is preferable. If the fiber diameter is too small, the fiber is easily cut, so that the fiber length is shortened during molding, and sufficient conductivity may not be obtained. On the other hand, if the fiber diameter is too long, entanglement of fibers is difficult to occur, and sufficient conductivity may not be obtained.

  The length of the conductive fiber (A) is preferably 3 to 15 mm, more preferably 4 to 10 mm. In order to efficiently obtain high conductivity and electromagnetic wave shielding effect, a longer fiber length is preferable, but if the fiber length is too long, the appearance, moldability, dispersibility, etc. of the molded product may not be good. . On the other hand, if the length of the fiber is too short, contact between the conductive fibers becomes difficult to occur, and the conductivity may be lowered.

  The number of conductive fibers (A) contained in the thermoplastic resin-coated conductive composition (E) is preferably from 100 to 300, more preferably from 150 to 250, and from 180 to 240. More preferably. When the number of conductive fibers is within this range, the dispersibility of the conductive fibers in the molded product is good, and sufficient conductive fiber contacts are formed, so that the conductivity is good and the appearance due to unopened fibers. There is no defect, and it is difficult for problems such as fibers to clog the screw of the molding machine. If the number of conductive fibers is too large, conducting a test that assumes repeated use in a low-temperature atmosphere and a high-temperature atmosphere, so-called heat shock test, the conductivity will decrease, the molding processability will deteriorate, and the appearance will be poor. May occur.

  The conductive fiber (A) may be coated with tin or a tin alloy from the viewpoint of corrosion resistance. Examples of the tin alloy include a tin-lead alloy, a tin-lead-silver alloy, and a tin-lead-bismuth alloy.

  The low melting point metal (B) used in the present invention preferably has a melting point lower than that of the conductive fiber (A) and exhibits good fusing property with the conductive fiber (A). The melting point of the low melting point metal (B) is preferably 300 ° C. or less, and more preferably 250 ° C. or less. The low melting point metal (B) is a metal that does not contain lead, and includes, for example, an alloy of tin as a main component and at least one metal species selected from the group consisting of tin, silver, zinc, and copper. .

  The cross-sectional shape of the rod-shaped low melting point metal (B) used in the present invention is not particularly limited, but is preferably substantially circular. The diameter of the low melting point metal (B) is preferably in the range of 0.01 to 5 mm, and more preferably 0.05 to 4 mm. More preferably, it is 0.1-3 mm. Here, the diameter of the low melting point metal (B) usually refers to the diameter when converted to a circle having the same cross-sectional area. When the diameter of the low melting point metal (B) is in the range of 0.01 to 5 mm, contact between the conductive fibers can be efficiently caused, and sufficient electromagnetic wave shielding characteristics can be obtained. If the diameter of the low-melting-point metal (B) is too small, it is likely to be cut at the time of manufacturing a molded product, and the manufacturing may be difficult. On the other hand, if the diameter of the low-melting-point metal (B) is too large, it tends to be difficult to melt at the time of molding, or molding troubles such as clogging with a screw or nozzle of a molding machine tend to occur.

  The length of the low melting point metal (B) in the present invention is preferably the same length as the above-described conductive fiber (A), preferably 3 to 15 mm, more preferably 5 to 10 mm. In order to efficiently obtain a high electromagnetic wave shielding effect, the longer the length, the better. However, if the length is too long, the appearance, moldability, dispersibility, etc. of the molded product may not be good. On the other hand, if the length is too short, the effect of promoting contact between conductive fibers entangled during molding tends to be small, and the electromagnetic shielding effect tends to be reduced.

  The low melting point metal (B) may contain a flux for the purpose of improving the fusibility with the conductive fiber (A). When the flux is contained, the content is preferably 0.1 to 5% by weight with respect to the low melting point metal (B). The flux is preferably contained in the low melting point metal (B). Examples of the flux include stearic acid, lactic acid, oleic acid, glutamic acid, rosin, and active rosin.

  The content of the low melting point metal (B) in the thermoplastic resin-coated conductive composition (E) is 4 to 45% by weight, preferably 10 to 35%, from the viewpoint of maintaining conductivity after the heat shock test. % By weight. If the content of the low melting point metal (B) is too small, the electromagnetic shielding property after the heat shock test tends to be lowered, and if too much, the fluidity of the thermoplastic resin-coated conductive composition is lowered and the molding processability is reduced. Tend to be inferior.

  The weight ratio of the conductive fiber (A) to the low melting point metal (B) in the thermoplastic resin-coated conductive composition (E), that is, (B) / (A) is 0.3 to 0.8. It is preferable. When the weight ratio is within this range, it is preferable from the viewpoint that conductivity is maintained even after the heat shock test. More preferably, it is 0.31-0.7. If the weight ratio (B) / (A) is less than 0.3, the conductivity tends to decrease after the heat shock test, and if it exceeds 0.8, the fluidity of the thermoplastic resin-coated conductive composition. There is a tendency that molding processability is inferior.

  The thermoplastic resin-coated conductive composition (E) used in the present invention is formed by coating the conductive fiber (A) and the low melting point metal (B) with a thermoplastic resin (C). Examples of the thermoplastic resin (C) include polypropylene resin, polyethylene resin, polyamide resin, ABS, polystyrene, polyphenylene ether resin, and blends and alloys of two or more of these resins. Of these, polypropylene resin is preferable.

  Examples of the polypropylene resin include a propylene homopolymer, a propylene-α-olefin random copolymer, a propylene-ethylene block copolymer, and the like, and these can be used alone or in combination. Here, examples of the α-olefin include α-olefins having 2 or 4 to 8 carbon atoms such as ethylene, butene-1, hexene-1, and octene-1.

  The thermoplastic resin (C) used in the present invention preferably has an MFR of 10 g / 10 min to 400 g / 10 min. When the MFR is less than 10 g / 10 min, the dispersibility of the conductive fibers decreases during molding, and the resulting molded product tends to have insufficient conductivity. Moreover, when MFR exceeds 400 g / 10min, there exists a tendency for the intensity | strength of the molded product obtained to fall.

  The content of the thermoplastic resin (C) in the thermoplastic resin-coated conductive composition (E) is 1 to 20% by weight when the weight of the composition (E) is 100%, and 5 to 15% by weight. % Is preferred. If the content of the thermoplastic resin (C) is less than 1% by weight, there is a tendency to impair the conductivity because the dispersion of the conductive fibers is impaired. If the content exceeds 20% by weight, the conductive fibers contact each other during molding. In order to prevent, there exists a tendency for the electroconductivity of the molded article obtained using this thermoplastic resin coating electrically conductive composition to fall.

  The thermoplastic resin-coated conductive composition (E) in the present invention is formed by coating a conductive fiber (A) and a low melting point metal (B) with a thermoplastic resin (C). As a state where the conductive fiber (A) and the low melting point metal (B) are coated with the thermoplastic resin (C), the bundle of the conductive fibers (A) and the low melting point metal (B) are aligned and heated. The state covered with the thermoplastic resin (C) or the state where the conductive fiber (A) is converged in the low melting point metal (B) may be covered with the thermoplastic resin (C). However, the conductive fiber (A) and the low melting point metal (B) can be efficiently contacted during molding, and excellent conductivity can be maintained after the heat shock test. It is preferable that the composite fiber bundle in which the low melting point metal (B) is converged in the fiber bundle is coated with the thermoplastic resin (C). As a state where the low melting point metal (B) is converged in the fiber bundle of the conductive fibers (A), the low melting point metal (B) is completely wrapped in the bundle of the conductive fibers (A). Either the state or the state where the low melting point metal (B) partially enters the bundle of conductive fibers (A), but also has a part that is partially exposed. When the form of the thermoplastic resin-coated conductive composition is as described above, the conductive fibers (A) and the low melting point metal (B) are efficiently contacted during molding, and excellent after the heat shock test. Conductivity can be maintained.

  The method for producing the thermoplastic resin-coated conductive composition (E) is not particularly limited, and a method of immersing the composite fiber bundle in the molten thermoplastic resin (C), or a composite fiber bundle and a thermoplastic resin. And then extruding from a die after melting the thermoplastic resin (C). The latter method is usually selected from the viewpoint of productivity. The temperature of the molten thermoplastic resin (C) during coating is preferably 20 to 80 ° C. higher than the melting point of the low melting point metal (B), and 30 to 70 ° C. is higher. More preferable from the viewpoint.

  When the composite fiber bundle and the thermoplastic resin (C) are charged into an extruder and the composite fiber bundle is coated with a molten thermoplastic resin, the surface temperature of the composite fiber bundle is preferably 50 to 200 ° C. More preferably, it is 200 degreeC, and it is further more preferable that it is 150-200 degreeC. By using a composite fiber bundle having a surface temperature in the above range, the low melting point metal adheres more efficiently to the contact points between the conductive fibers, so that the conductivity becomes better.

  The composite fiber bundle coated with the thermoplastic resin is usually subsequently cut into an appropriate size into pellets. The cross-sectional shape of the pellet is not particularly limited, and is usually circular or flat.

  In the present invention, the thermoplastic resin-coated conductive composition (E) 5 to 60% by weight and the thermoplastic resin (D) 95 to 40% by weight are mixed and injection molded to form a thermoplastic resin. Manufacturing goods. The thermoplastic resin (D) is an endothermic curve obtained by measuring the thermoplastic resin (C) with a differential scanning calorimeter (DSC) at a temperature rising rate of 10 ° C./min. Among the peaks observed in the range, the peak (Pc) indicating the maximum temperature and the thermoplastic resin (D) are obtained by using a differential scanning calorimeter (DSC) and measuring at a heating rate of 10 ° C./min. In the endothermic curve, among the peaks observed in the range of 50 to 300 ° C., the peak (Pd) indicating the maximum temperature is a thermoplastic resin satisfying Pc + 20 ≦ Pd (° C.). As a result of measuring each resin, when a plurality of peaks are observed in the range of 50 to 300 ° C., the peaks showing the highest temperature are defined as Pc and Pd.

  The peak observed under the above conditions may be a peak showing a glass transition temperature or a peak showing a melting point. That is, the thermoplastic resins (C) and (D) may both be amorphous resins or crystalline resins. For example, both of the thermoplastic resins (C) and (D) may be a crystalline resin or an amorphous resin, or one of them may be a crystalline resin and the other may be an amorphous resin.

  Examples of the thermoplastic resin (C) include polypropylene resin, polyethylene resin, polyamide resin, ABS, polystyrene, polyphenylene ether resin, and blends and alloys of two or more of these resins. Of these, polypropylene resin and polyamide / polypropylene alloy are preferable.

When performing injection molding, add various additives such as fillers, antioxidants, copper damage inhibitors, UV absorbers, radical scavengers, thermoplastic elastomers, metal powders, etc. according to the required physical properties. Also good. These additives may be contained in advance in the thermoplastic resin-coated conductive composition (E) and / or the thermoplastic resin (D).
When adding metal powder, copper powder, brass powder, nickel powder, aluminum powder, zinc powder, tin powder, etc. can be used, for example. You may use these in mixture of 2 or more types. Of these, aluminum powder is preferably used. It is preferable to mix | blend content of metal powder so that it may become 0.5 to 10 weight% in a molded article from an electroconductive viewpoint. The metal powder may be used as it is in the form of a powder, but may be used as a master pellet with a flake or flake, or a thermoplastic resin such as polypropylene or polyethylene.

  The temperature at the time of injection molding is preferably equal to or higher than the melting point of the low melting point metal. Also, a chemical foaming agent or a physical foaming agent may be blended at the time of molding to perform foam molding.

  The shape of the molded product obtained by the production method of the present invention is not particularly limited. Moreover, you may laminate | stack another layer on the obtained molded article.

  Since the thermoplastic resin molded product obtained by the production method of the present invention is sufficiently opened, there are few appearance defects. In addition, the molded article is excellent in electromagnetic wave shielding properties having electromagnetic wave shielding properties exceeding 30 dB in a magnetic wave of 2 to 30 MHz by an Advantest method which is one of methods for evaluating electromagnetic wave shielding properties. Furthermore, even after conducting a heat shock test in which exposure is repeated 300 times or more in an atmosphere of −30 ° C. and 80 ° C., conductivity can be maintained.

EXAMPLES Hereinafter, although this invention is demonstrated using an Example, it cannot be overemphasized that this invention is not limited by an Example.
The injection molding machine, mold, molded product shape, and evaluation method used in the examples are as follows.

The melting points of the thermoplastic resins (C) and (D) were measured as follows.
Apparatus: Differential scanning calorimetry (DSC) (Seiko Electronics Co., Ltd.)
Measurement conditions: Measurement temperature 20 ° C to 300 ° C
Temperature increase rate 10 ℃ / min

Molding of test pieces for evaluating conductivity and evaluation of conductivity were performed as follows.
(1) Injection molding machine and mold, molding conditions Injection molding machine: manufactured by Nippon Steel Works J150E Clamping force 150 tons Molding temperature: 270 ° C
Mold: 150 x 150 x 2mm thickness
Mold temperature: 40 ℃
(2) Measurement of conductivity <Measurement of internal resistance value>
After driving copper screws into the four corners of the molded product obtained in the above (1) so as to be about 100 mm apart, the resistance value between the two screws was measured using a milliohm tester. The resistance value was measured. The smaller the internal resistance value, the better the conductivity.
(3) Heat shock test (cooling test)
Uses a thermal shock tester (made by Tabay Espec).
Test conditions: low temperature bath temperature -30 ° C, low temperature exposure time 30 minutes, high temperature bath temperature 80 ° C, high temperature exposure time 25 minutes, 300 cycles of moving sample from low temperature bath to high temperature bath did.

[Example 1]
As the conductive fiber (A), 216 copper fibers having a fiber diameter of 50 μm and one lead-free solder having a diameter of 500 μm were used as the low melting point metal (B). A composite fiber bundle in which the low melting point metal (B) is converged during the convergence of the conductive fiber (A) is used as a thermoplastic resin (C), and a propylene homopolymer (MFR 100 g / 10 min, manufactured by Sumitomo Chemical Co., Ltd., registered trademark Sumitomo) Extruded through a 40 mmφ extruder die together with Nobrene U501E1), the surface of the composite fiber bundle was coated with a propylene homopolymer, and then cut into a pellet length of 6 mm to produce a thermoplastic resin-coated conductive composition. The composition of the obtained thermoplastic resin-coated conductive composition was 67.5% by weight of copper fibers, 22.5% by weight of lead-free solder, and 10% by weight of propylene homopolymer.
26% by weight of the thermoplastic resin-coated conductive composition (E) and 74% by weight of a polyamide / polypropylene polymer alloy (manufactured by Sumitomo Chemical, registered trademark Propalloy A14M25, MFR g / 10 min) as the thermoplastic resin (D), Furthermore, after dry blending 11 parts by weight of a copper damage inhibitor masterbatch (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen MB109) with respect to a total weight of 100 parts by weight of the composition (E) and the thermoplastic resin (D), a molding temperature was obtained. Injection molding was performed under conditions of 270 ° C. and a mold temperature of 40 ° C. to produce a molded product having a thickness of 150 × 150 × 2 mm. The internal resistance value of the obtained molded product was measured before and after the heat shock test. The results are shown in Table 1.

[Comparative Example 1]
As the conductive fiber (A), 216 copper fibers having a fiber diameter of 50 μm and one lead-free solder having a diameter of 500 μm were used as the low melting point metal (B). The composite fiber bundle in which the low melting point metal (B) is converged during the convergence of the conductive fiber (A) is used as the thermoplastic resin (C), and the propylene-ethylene random copolymer (C) (MFR 30 g / 10 min, Sumitomo Chemical). Extruded through a 40 mmφ extruder die together with a registered trademark Sumitomo Noblen Z144A), coated with a propylene homopolymer on the surface of the composite fiber bundle, then cut into a pellet length of 6 mm, and coated with a thermoplastic resin conductive composition The thing was manufactured. The composition of the obtained thermoplastic resin-coated conductive composition was 67.5% by weight of copper fibers, 22.5% by weight of lead-free solder, and 10% by weight of propylene-ethylene random copolymer.
The thermoplastic resin-coated conductive composition (E) 26% by weight and, as the thermoplastic resin (D), propylene-ethylene copolymer (manufactured by Sumitomo Chemical, registered trademark Sumitomo Nobrene AZ161T, MFR 30 g / 10 min) 74% by weight, Furthermore, after dry blending 11 parts by weight of a copper damage inhibitor masterbatch (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen MB109) with respect to a total weight of 100 parts by weight of the composition (E) and the thermoplastic resin (D), a molding temperature was obtained. Injection molding was performed under conditions of 270 ° C. and a mold temperature of 40 ° C. to produce a molded product having a thickness of 150 × 150 × 2 mm. The internal resistance value of the obtained molded product was measured before and after the heat shock test. The results are shown in Table 1.

[Comparative Example 2]
As the conductive fiber (A), 216 copper fibers having a fiber diameter of 50 μm and one lead-free solder having a diameter of 500 μm were used as the low melting point metal (B). A composite fiber bundle in which the low melting point metal (B) is converged during the convergence of the conductive fiber (A) is used as a thermoplastic resin (C), and a propylene homopolymer (MFR 100 g / 10 min, manufactured by Sumitomo Chemical Co., Ltd., registered trademark Sumitomo) Both Noblene U501E1) were extruded through a die of a 40 mmφ extruder, and the surface of the composite fiber bundle was coated with a propylene homopolymer, and then cut into a pellet length of 6 mm to produce a thermoplastic resin-coated conductive composition. The composition of the obtained thermoplastic resin-coated conductive composition was 67.5% by weight of copper fibers, 22.5% by weight of lead-free solder, and 10% by weight of propylene homopolymer.
The thermoplastic resin-coated conductive composition (E) 26% by weight and, as the thermoplastic resin (D), propylene-ethylene copolymer (manufactured by Sumitomo Chemical, registered trademark Sumitomo Nobrene AZ161T, MFR 30 g / 10 min) 74% by weight, Furthermore, after dry blending 11 parts by weight of a copper damage inhibitor masterbatch (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen MB109) with respect to a total weight of 100 parts by weight of the composition (E) and the thermoplastic resin (D), a molding temperature was obtained. Injection molding was performed under conditions of 270 ° C. and a mold temperature of 40 ° C. to produce a molded product having a thickness of 150 × 150 × 2 mm. The internal resistance value of the obtained molded product was measured before and after the heat shock test. The results are shown in Table 1.

[Comparative Example 3]
As the conductive fiber (A), 216 copper fibers having a fiber diameter of 50 μm and one lead-free solder having a diameter of 500 μm were used as the low melting point metal (B). A composite fiber bundle in which the low melting point metal (B) is converged during the convergence of the conductive fiber (A) is used as a thermoplastic resin (C), and a propylene homopolymer (MFR 100 g / 10 min, manufactured by Sumitomo Chemical Co., Ltd., registered trademark Sumitomo) Both Noblene U501E1) were extruded through a die of a 40 mmφ extruder, and the surface of the composite fiber bundle was coated with a propylene homopolymer, and then cut into a pellet length of 6 mm to produce a thermoplastic resin-coated conductive composition. The composition of the obtained thermoplastic resin-coated conductive composition was 67.5% by weight of copper fibers, 22.5% by weight of lead-free solder, and 10% by weight of propylene homopolymer.
26% by weight of the thermoplastic resin-coated conductive composition (E) and, as the thermoplastic resin (D), a propylene-ethylene random copolymer (C) (MFR 30 g / 10 min, manufactured by Sumitomo Chemical Co., Ltd., registered trademark Sumitomo Nobrene Z144A) 74% by weight, and further 11 parts by weight of a copper damage preventive masterbatch (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Nobrene MB109) was dry blended with respect to 100 parts by weight of the total weight of the composition (E) and the thermoplastic resin (D). Thereafter, injection molding was performed under conditions of a molding temperature of 270 ° C. and a mold temperature of 40 ° C. to produce a molded product having a thickness of 150 × 150 × 2 mm. The internal resistance value of the obtained molded product was measured before and after the heat shock test. The results are shown in Table 1.

※ＤＳＣ測定では、１６７℃と２２４℃にピークが観測された

* In DSC measurement, peaks were observed at 167 ° C and 224 ° C.

Claims (1)

A method for producing a molded article made of a conductive thermoplastic resin, comprising a conductive fiber (A), a rod-shaped low melting point metal (B) having a melting point lower than that of the conductive fiber (A), and a polypropylene resin (C). The polypropylene resin- coated conductive composition (E) satisfying the following requirements (1) and (2): 5 to 60% by weight, and the thermoplastic resin (D) satisfying the following requirement (3): 95 to 40% by weight A method for producing a molded product made of a conductive thermoplastic resin by mixing and injection molding.
(1) The conductive fiber (A) and the low melting point metal (B) are coated with the polypropylene resin (C). (2) The weight of the thermoplastic resin-coated conductive composition (E) is 100%. When the conductive fiber (A) content is 35 to 95% by weight, the low melting point metal (B) content is 4 to 45% by weight, and the polypropylene resin (C) content is 1 to 20% by weight. (3) Of the peaks observed in the range of 50 to 300 ° C. in the endothermic curve obtained by measuring the polypropylene resin (C) with a differential scanning calorimeter (DSC) at a temperature rising rate of 10 ° C./min. In an endothermic curve obtained by measuring a peak (Pc) indicating the maximum temperature and a thermoplastic resin (D) using a differential scanning calorimeter (DSC) at a temperature rising rate of 10 ° C./min, 50 to 300 ° C. The highest temperature among the peaks observed in the range Peak (Pd) indicating a, but with Pc + 20 ≦ Pd (℃)