JPS6351459A - Electrically conductive molding material - Google Patents

Abstract

PURPOSE:To obtain a molding material containing uniformly dispersed electrically conductive fibers and giving a molded article having excellent electrical conductivity using a decreased amount of the conductive fiber, by mixing natural pellets with master pellets produced by coating conductive fibers with a sizing agent containing a chemical foaming agent an cutting the collected fibers. CONSTITUTION:The objective material is produced by compounding 50-20,000 conductive fibers (e.g. stainless steel fiber) with 5-40wt.% sizing agent containing a thermoplastic resin (e.g. vinyl chloride resin) and 5-30wt.% chemi cal foaming agent (e.g. azodicarbonamide) based on said resin to coat and collect said fibers with the sizing agent, cutting the mixture in the form of pellets having a length of 3-12mm and compounding the resultant master pellets to natural pellets (e.g. polystyrene) at an amount of 2-40wt.%.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Field of Application) The present invention provides a method for producing a molded product having good dispersibility of conductive + i fibers, requiring a small fiber filling rate, and having excellent conductivity of a molded product. 7H molding material.

(Prior art) Conventionally, conductive tilt-I consisting of a large number of filaments
When filling and dispersing T in a thermoplastic resin to make a conductive resin composition, first, gold RIB fibers are mixed with a thermoplastic resin solution or emulsion sizing agent, as shown in Japanese Patent Publication No. 60-54967. converge using 1 to 15 mm
Next, the cut convergent fibers are mixed with thermoplastic plastic and cross-dispersed using an extruder to produce a conductive plastic. Furthermore, JP-A-58-1290
As disclosed in Japanese Patent No. 31, the cross-dispersed conductive plastic was cut into pellets with a pelletizer to facilitate injection molding.

However, the above-mentioned conventional conductive resin composition does not contain gold inside the heating cylinder of the extruder in the previous crosstalk dispersion step. Since rS fibers are cross-dispersed, there is a drawback that the fibers tend to break easily. In addition, in the later pelletizing process, the fibers are cut again to make them into pellets, so the fibers are further cut.
There was a drawback that the length of the fiber w1 was much shorter than the original length.

Furthermore, when conventional conductive resin compositions are used to make molded products, the conductivity decreases over time or the desired conductivity cannot be obtained.
It is necessary to increase 1ffi, and as a result, the moldability and physical properties of the molded product are impaired, and the cost is also increased, which has been a problem.

(Problems to be Solved by the Invention) The present invention has been made to eliminate the drawbacks of the conventional conductive resin compositions described above, and has good dispersibility of conductive fibers, even at a low fiber filling rate. It is an object of the present invention to provide a conductive molded material at which has excellent conductivity and does not impair the physical properties of the resin.

[Structure of the invention] (Means and effects for solving the problems) In order to achieve the above-mentioned object, the present invention has conducted extensive research, and as a result, it has been discovered that the main cause of the loss of conductivity is the cutting of U and navy blue. By omitting the cross-dispersion process using an extruder for thermoplastic resin and conductive fibers, and by using a chemical foaming agent as a sizing agent, the dispersibility of conductive fibers into thermoplastic resin during injection molding is good, and low fiber The present invention was completed based on the discovery that the material has excellent electrical conductivity in terms of filling rate and does not impair the physical properties of the molded product. That is, the present invention mixes a master pellet obtained by coating and converging conductive fibers with a convergence agent containing a thermoplastic resin and a chemical foaming agent, and cutting the conductive fibers into pellets, and natural pellets made of a thermoplastic resin. This is an electrically conductive molding material characterized by:

The conductive fibers used in the present invention include stainless steel fibers,
Aluminum fibers, copper fibers, carbon fibers or carbon fibers with a gold dust plating layer on the surface, glass fibers, or aluminum fibers. These can be used alone or in a mixture of two or more.

The number of filaments of the conductive fibers converged with the convergence agent is 5.
00-20. Approximately O'00 is appropriate.

The sizing agent used in the present invention contains a thermoplastic resin and a chemical blowing agent. The thermoplastic resins used here include vinyl chloride resin, ethylene vinyl acetate resin, polystyrene resin, ΔS resin, ABS resin, polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polybutylene terephthalate resin, nylon resin, polycarbonate resin, and modified resin. Examples include polyphenylene oxide resin, polyphenylene sulfide resin, polyether sulfone resin, polyetherimide resin, etc., and these may be used alone or in combination of two or more.

In addition, as a chemical blowing agent, azodicarbonamide (A
DCA), azobisisobutyronitrile (△IBN),
4,4'-Oxybisbenzenesulfonyl hydrazide (OB S l-1), N,N'-dinitrirosopentamethylenetetramine (DPT), +1-toluenesulfonylhydrazide (TSSC), p-toluenesulfonylhydra Examples include TSH (TSH) and trihydrazotriazine (THT), which may be used alone or in combination of two or more. Further, it is also possible to use a chemical foaming agent in which a foaming aid is added to these chemical foaming agents as necessary, and the foaming temperature and gas are adjusted.

Examples of foaming aids include inorganic salts such as zinc white, tribasic lead sulfate, and white oxide, metal soaps such as zinc stearate and lead stearin M, and urea compounds, which may be used alone or in combination of two or more. used.

Furthermore, thermoplastic resins with chemical blowing agents added in advance are commercially available, and these may also be added. For example, thermoplastic resins containing chemical blowing agents include FCJ-110 (for Noryl), manufactured by Engineer Glass Co., Ltd., and FVC.
-60/65 (for PBT), Hydration Kasei Kogyo Co., Ltd. product name, Polysrene E-EE-106, io5,201, etc., and these may be used alone or in combination of two or more.

It is desirable that the chemical blowing agent be blended in an amount of 5 to 30% by weight based on the thermoplastic resin contained in the sizing agent.

If the blending ratio is less than 5% by weight, the foaming gas pressure will be insufficient and the dispersion of the conductive fibers will be poor, which is not preferable. Moreover, if it exceeds 30 mm%, the molded product itself becomes a foamed molded product, which is not preferable as a normal molded product.

There are no particular restrictions on the method of coating and converging the conductive fibers with a sizing agent, and any method may be used. Preferred methods include a method of dipping the conductive fibers, a method of heating and melting the sizing agent, extruding it from the extruder, and simultaneously passing the continuous conductive fiber through the center of the die of the extruder to coat the conductive fibers with the sizing agent and converging them. Adopted. It is desirable that the adhesion of the sizing agent be 5 to 40% by weight with respect to the conductive fibers.If it is less than 5% by weight, the foaming pressure will be insufficient and the dispersibility will be poor, and if it exceeds 40% by weight, it will be difficult to heat. This is undesirable as it impairs the physical properties of the plastic resin. II. The conductive U&fibers are thus coated with a binder and converged, dried or cooled, and cut into pellets to give a conductive molding material.

The length of this pellet is preferably 3 to 12 mm. If the length is less than 3 mm, the conductivity will be low, and if it exceeds 12 mm, the dispersibility of the conductive fibers will be poor, and when molded, the molded product will have a lattice part etc. The conductive fibers are not filled in the details, which is not preferable.

In the method of extrusion coating and convergence of conductive fibers with a heat-melted convergence agent, if the matrix thermoplastic resin is a material with excellent solvent resistance, such as polyethylene terephthalate, polybutylene terephthalate, or nylon, it is difficult to dissolve in common solvents. Since this method requires the use of strongly polar solvents, it is useful as a method that does not use these solvents. After the extrusion coating is finished, the S-containing impurities are dispersed by applying pressure to a flat surface, and the master pellets are cut into pellets.Natural pellets made of thermoplastic resin are blended with the master pellets to obtain a conductive molding material. The mixing ratio of master pellets and natural pellets is preferably 2 to 30 fflff1% relative to the natural pellets.

If the blending ratio is less than 2% by weight, the conductivity will be low and the S conductivity will quickly deteriorate due to heat, which is not preferred. Also 30% by weight
If it exceeds this value, the properties of the thermoplastic resin, which is a natural pellet, will deteriorate, and the overall weight will become heavy, which is undesirable.

These natural pellets include polystyrene, polyethylene vinyl acetate, acrylonitrile styrene copolymer (As), ABS, polycarbonate,
Examples include polyethylene terephthalate, polybutylene terephthalate, nylon, modified polyphenylene oxide, polysulfone, polyphenylene nulphide, and polyetherimide, and these may be used alone or in combination of two or more.

Injection molding is heated in a cylinder by the chemical blowing agent contained in the sizing agent or natural pellets, the chemical blowing agent decomposes, generates nitrogen gas and carbon dioxide gas, and foams, using the gas pressure. The conductive fibers are dispersed and further dispersed and kneaded using an 04 molding machine.
Therefore, the conductive fibers are less likely to be cut by the injection molding machine, and a molded article that is well dispersed and has excellent conductivity can be obtained.

(Examples) Next, the present invention will be specifically explained by examples, but the present invention is not limited by these examples.

In the following Examples and Comparative Examples, "1%" means [heavy mother%
” means.

Example 1 20% of a chemical blowing agent azodicarbonamide (ADCA) was added to thermoplastic resin TFX-410 (ABS resin manufactured by Mitsubishi Monlint Kasei Co., Ltd., trade name), and this was thoroughly stirred in twice the amount of methylene chloride. It was used as a convergence agent. Carbon fiber H (8 μm in diameter, 12,000 filaments) was added to this solution.
The solution was then dried to volatilize the solvent.
At this time, the proportions of ABS81 fat, carbon fiber, and ADCA are as follows:
The weight ratios were 16%, 80%, and 4%. This is 61
Cut into 11m pellets to make master pellets.
Natural pellets TFX-410 were added to this to obtain a conductive molding material. Injection molding was performed using this molding material, and a molded product weighing 1 q was obtained. At this time, the carbon fiber content in the molded article was 20%. Performs X-ray imaging of the molded product,
First, we evaluated the dispersibility of carbon fibers and tested the S conductivity.
As shown in the table, the excellent effects of the present invention were confirmed.

Example 2 10% of chemical blowing agent Gonihole SW #9 (ADCΔ, product name, manufactured by Hydration Kasei Co., Ltd.) was added to thermoplastic resin HF-55 (polystyrene resin, product name, manufactured by Mitsubishi Monsando Kasei Co., Ltd.)
This was added to 4 times the amount of methylene chloride and thoroughly stirred to prepare a sizing agent. Add stainless steel fibers (diameter 8 μm) to this solution.
10,000 filaments) were passed through the tube, and then dried to volatilize the solvent. In this case, the proportions of polystyrene resin, navy blue stainless steel fiber, and ADCA are ffuf
The M ratio was 18%, 80%, and 2%. This length is 6
The master pellet was cut into pellets of mm in size, and polystyrene resin H65 (high impact polystyrene resin manufactured by Nippon Steel Chemical Co., Ltd., trade name) was added thereto as natural pellets and mixed to obtain a conductive molding material. Injection molding was performed using this molding material to obtain a molded product. The mixing ratio of stainless steel fiber miscellaneous and polystyrene resin (natural pellets) is the stainless steel mv contained in the molded product.
It was blended so that L was 7%. The molded product was tested in the same manner as in Example 1, and the results are shown in Table 1, confirming the excellent effects of the present invention.

Example 3 Polyethylene resin polysene E-EE- with chemical blowing agent
205 (manufactured by Hydration Kasei Co., Ltd., trade name), carbon fibers (diameter 8 μm, 12,000 filaments) with a nickel plating layer on the surface were extruded so as to cover and converge, and then pressed flat with a roll. and cool it down to a length of 6n+n.
It was cut into + pellets to obtain master pellets.
This was mixed with polypropylene resin as natural pellets to create a conductive molding material. Injection molding was performed using this molding material to yield 1 q of molded products. Polystyrene E-EE-20 coating carbon fiber with nickel plating layer
5 is 30%, and the mixing ratio with polypropylene (natural pellets) is such that the UVt contained in the molded product is 1.
It was blended so that it was 2%.

The molded product was tested in the same manner as in Example 1, and the results are shown in Table 1, confirming the excellent effects of the present invention.

Comparative Example 1 Carbon IM (diameter 8 μm, number of filaments 12,000
) and then dried to remove the solvent.
The proportions of ABS resin and carbon fiber at this time were 20% and 8%.
It was 0%. This was cut into pellets with a length of 6 mm to obtain master pellets, and natural pellets made of ABS resin were mixed to obtain a conductive molding material. Injection molding was performed using this molding material to obtain a molded product. It was blended so that [t] contained in the molded product was 20%. Tests were conducted on this molded product using Examples and studs, and the results are shown in Table 1.

Comparative Example 2 A stainless steel [ff (diameter: 8 μm, number of filaments: 10,000) was passed through a solution prepared by dissolving a high impact polystyrene resin as a thermoplastic resin in methylene chloride, and then dried to volatilize the solvent.

At this time, the proportions of polystyrene resin and stainless steel aVt were 20% and 80%. This was cut into pellets with a length of 6n+m to obtain master pellets, and natural pellets made of high impact polystyrene resin were added and mixed to obtain a conductive molding material. The proportion of stainless steel fiber at this time was 7% by weight. Using this molding material, injection molding was performed in the same manner as in Comparative Example 1 to obtain a molded product.

This molded article was tested in the same manner as in Example 1, and the results are shown in Table 1.

Table 1 *1: Product name of polyethylene resin containing chemical foaming agent, manufactured by Eiwa Kasei Co., Ltd. *2: Azodicarbonamide *3: Product name of azodicarbonamide, manufactured by Eiwa Kasei Co., Ltd. *4: Dispersibility was evaluated. ○ mark is good, X mark is bad.

[Effects of the Invention] As is clear from the above explanation and Table 1, the conductive molding material of the present invention uses a convergent light foaming agent as the tilil convergence agent, so that the thermoplastic resin and the conductive taN
There is no need for a mixed separation process using an extruder to disperse the resin, and as a result, a small amount of conductive U and fiber can be filled, resulting in conductive molding that has excellent conductivity and does not impair the properties of the matrix resin. It is the material. Therefore, by using the conductive molding material of the present invention, highly reliable molded products for electronic devices can be obtained.

Claims (1)

[Claims] 1. A master pellet obtained by coating and converging conductive fibers with a convergence agent containing a thermoplastic resin and a chemical foaming agent and cutting them into pellets, and a natural pellet made of a thermoplastic resin are mixed. A conductive molding material that is characterized by its properties. 2 The chemical blowing agent is azodicarbonamide, azobisisobutyronitrile, 4,4'-oxybisbenzenesulfonylhydrazide, p-toluenesulfonylhydrazide, trihydrazotriazine, p-toluenesulfonyl semicarbazide, or The conductive molding material according to claim 1, which is N,N'-dinitrosopentamethylenetetramine. 3. The conductive molding material according to claim 1 or 2, wherein the chemical blowing agent is blended in a proportion of 5 to 30% by weight based on the thermoplastic resin contained in the sizing agent. 4. The conductive molding material according to any one of claims 1 to 3, wherein the sizing agent is blended in a proportion of 5 to 40% by weight based on the conductive fibers. 5. The conductive molding material according to any one of claims 1 to 4, wherein a binding agent is dissolved in a solvent, and conductive fibers are immersed in the coating material. 6 Heat and melt the binding agent, extrude it from the extruder, and at the same time pass the continuous conductive fiber through the center of the extruder die, cover the conductive fiber with the binding agent, converge it, cool it, and cut it into pellets. Claims 1 to 4
The conductive molding material described in any of the above. 7. The conductive fiber according to any one of claims 1 to 6, wherein the conductive fiber is stainless steel fiber, aluminum fiber, copper fiber, carbon fiber, carbon fiber having a metal plating layer on the surface, glass fiber, or organic fiber. Conductive molding material. 8 The number of conductive fibers coated and bundled with a binding agent is 500 to 500.
Claims 1 to 7 which are 20,000 pieces
The conductive molding material described in any of the above. 9. The conductive molding material according to any one of claims 1 to 8, wherein the master pellet has a length of 3 to 12 mm. 10 Claim 1 in which master pellets are blended at a ratio of 2 to 40% by weight relative to natural pellets
The conductive molding material according to any one of Items 1 to 9.