JPS6151061A - Electrical conductive resin molding material and production thereof - Google Patents

Abstract

PURPOSE:To obtain the titled molding material having excellent moldability and electrical conductivity in a short time by a simple method, by depositing a thermoplastic resin agglomerated from a thermoplastic resin latex on an electrically conductive solid material. CONSTITUTION:50-99wt% (based on the amount of the resulting electrical conductive molding material) electrical conductive solid (e.g. natural graphite or Ni powder) is dispersed in an aq. medium, and a charge-imparting agent such as a cationic surfactant (e.g. cetyltrimethylammonium bromide) is added thereto and adsorbed by the solid material. A thermoplastic resin latex (e.g. anionic PVC latex) which is oppositely charged is added thereto and the mixture is stirred to allow the solid material and fine polymer particles in the latex to cause heteroagglomeration. The heteroagglomerate is recovered by filtration, washed with water and dried to obtain the titled molding material in which said electrical conductive solid material and the thermoplastic resin are mixed with each other microscopically and homogeneously.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to electric wire-related applications such as high-voltage cables and communication cables, plastic snack-related applications such as fuel tanks, electronic parts, packaging materials, and automobile parts, and hoses. The present invention relates to a conductive resin molding material that is widely used today in rubber-related applications such as belts, safety shoes, flooring materials, switching elements, switches, ignition cables, static eliminating rolls, and electrode-related applications.

[Conventional technology]

Up until now, in the production of electrically conductive resin molded products, plasticizers, stabilizers, antioxidants, ultraviolet absorbers, etc. have been added to the synthetic resin as necessary, and carbon black, graphite, metal powder, gold M4M fibers, etc. have been added to the synthetic resin. , conductive solid materials such as carbon fibers are cross-mixed using a suitable blender such as a co-kneader, panburi mixer, mixing roll, pressure kneader, etc., and after pelletizing if necessary, press molding, extrusion molding, or injection molding. , sheeting, and other methods have been adopted to form the desired product.

However, in this method of kneading and mixing 3 g of conductive solid material into synthetic resin, the content of the conductive solid material is 50%.
Exceeding the weight percentage will deteriorate kneading and moldability. For example, even when graphite is kneaded into polyethylene resin using a mixing roll, the graphite content will be at the limit of approximately 651 m%, and the volume resistivity of the molded product will decrease. The resistance was less than 27 Ωcm, making it impossible to produce a highly conductive resin molded product.

Therefore, first, a vinyl monomer was graft-polymerized on the surface of a conductive solid powder to form a solid-resin graph 1 polymer composition, and this solid-resin graft composite composition was molded to provide a conductive material with significantly improved conductivity. It has been proposed to obtain a transparent thin film material (Japanese Patent Application Laid-Open No. 56-90821).

[Problem that the invention seeks to solve]

However, in the previous invention in which a vinyl monomer is graft-polymerized on the surface of a conductive solid powder, a resin composition with high conductivity can be obtained, but the manufacturing process involves a complicated polymerization operation and takes a long time. There is a problem in that a process is required.

[Means to solve the problem]

The present invention was devised in view of this point of view, and is a conductive resin molding material that not only has high conductivity but also can be manufactured in a short time using a simple manufacturing method, and has good moldability. It provides:

That is, the present invention is a conductive resin molding material in which a thermoplastic resin aggregated from a thermoplastic resin latex is attached to a conductive solid substance, and a manufacturing method using the thermoplastic resin latex.

In the present invention, examples of the conductive solid substance include silver,
Metal powders or synthetic fibers such as copper, nickel, aluminum, and stainless steel, various metal-plated inorganic fillers, carbon blacks such as Ketjen black, acetylene black, and furnace black, natural or artificial graphite, carbon fibers, graphite fibers, etc. Carbon fibers, etc. can be mentioned. These conductive solid substances can be used alone or in combination of two or more.

Furthermore, the thermoplastic resin latex used in the present invention is
It includes not only latex synthesized by emulsion polymerization, but also dispersions in which polymeric substances are dispersed in an aqueous medium by appropriate means.The medium includes not only water but also water containing an organic solvent. It may be a mixed aqueous medium, or it may be a latex containing a plasticizer, stabilizer, ultraviolet absorber, other additives, etc. as necessary.

Examples of such thermoplastic resin latex include rubber latex such as styrene-butadiene rubber latex, polyisoprene latex, polychloroprene latex, methyl methacrylate-butadiene rubber latex, polyurethane water/dispersion, and polymethacrylic acid. Polyacrylate emulsions such as methyl latex, methyl methacrylate-styrene copolymer latex, methyl methacrylate-butyl methacrylate copolymer latex, polyvinyl acetate latex, ethylene-vinyl acetate copolymer latex, etc. Vinyl acetate emulsion, polyvinyl chloride latex, vinyl chloride
Examples include polyvinyl chloride emulsions such as vinylidene chloride copolymer latex, polyolefin dispersions such as polyethylene emulsions, polybutene emuls, diones, and other polystyrene latexes and silicone emulsions. These thermoplastic latexes may be used alone;
Moreover, 2Fn or more can also be used in combination.

Further, in the present invention, the method of attaching the thermoplastic resin aggregated from the thermoplastic resin latex to the conductive solid substance includes, for example, thoroughly kneading both of them by appropriate means and then drying the mixed wire. In a simple method, after mixing an i9 conductive solid substance with a thermoplastic resin latex as it is or as an aqueous medium dispersion in an aqueous medium, adding a substance that destabilizes the mixed latex, and/or Alternatively, a method can be adopted in which non-specific aggregation with polymer fine particles in the mixed latex is caused by destabilizing means such as freezing, followed by filtration, washing with water, and drying. In the latter method, the substance that destabilizes the mixed latex, that is, the latex destroyer, includes an electrolyte that compresses the electric double layer, an ionic surfactant that is effective for neutralizing the charge of the mixed latex,
Examples include polymer flocculants, other polar water-soluble organic solvents such as ketones and alcohols.

Furthermore, as a means to destabilize mixed latex,
Known means such as dispersion destruction effect by mechanical operations such as high-speed stirring and mechanical friction, and coagulation of latex by freezing-a-thawing can be employed.

Although it is possible to produce a conductive resin molding material by the above method, in order to obtain a more homogeneous solid resin composite material, it is preferable to use a heterogeneous material between the 3g conductive material and the thermoplastic resin latex. The solution is to adopt a method that applies agglomeration. That is, a conductive solid substance is dispersed in an aqueous medium, a charge imparting substance capable of imparting a charge to the conductive solid substance is added to the aqueous medium, and the charge imparting substance is adsorbed onto the conductive solid substance. After that, a thermoplastic resin latex having a charge opposite to that imparted to the conductive solid material is added, thereby causing heteroaggregation of the conductive solid material and the polymer particles in the latex, followed by filtration and water washing. This method involves post-drying.

The charge-imparting substances used in the method applying this heterocoagulation include, when the conductive solid material is carbonaceous, setting the pH of the medium to an alkaline side and negatively charging the carboxyl groups on the solid surface; When the conductive solid substance is gold rrAN, an electrolyte consisting of a potential state 2 ÷ constant ion that can be charged by a method such as electrification avoidance 8 by utilizing the addition and desorption of protons to the hydroxyl groups of the surface oxide film. , fvl , Ca2”, 2+
2÷ 24 3+
3÷3r, 3a 1zn, AI
, la 1Cc , an electrolyte consisting of polyvalent cations of Ttr" + Kasa, an electrolyte consisting of polyvalent anions of 3+ 8O, CrO, Fe(CN) rf, dodecyl ammonium chloride, cetyltrimethylammonium bromide, dodecylpyridinium chloride, etc. cationic surfactants such as sodium oleate, sodium lauryl sulfate, and sodium dodecylbenzenesulfonate; cationic polymer electrolytes such as polydiethylaminoethyl methacrylate, polyvinylpyridinium chloride, polyethyleneimine, and methyl glycol chitosan; Examples include delytes and anionic polymer electrolytes such as sodium polyacrylate, partial hydrolyzate of polyacrylamide, and potassium polyvinyl sulfate.These charge-imparting substances can be used alone, or , two or more types can also be used in combination.

According to the present invention, the content of the conductive solid substance J5 in the conductive resin molding material is J:
It is decided, but usually 50~'99FF!
ffi%, [or 60 to 95 mm%, more preferably 75 to 95 mm%. When the content of the conductive solid substance is less than 50 mω%, the volume resistivity of the resulting conductive resin molding material may be 100 or more, and molding may be possible using methods other than the method of the present invention. Further, it is difficult to increase the content of the conductive solid substance to more than 99% by weight.

Methods for producing resin molded products using the conductive resin molding material obtained by the present invention include calendar molding,
Any molding method such as extrusion molding, compression molding, lamination molding, injection molding, etc. can be employed, and can be appropriately selected depending on the shape of the resin molded product.

In addition, the conductive resin molding material obtained by the present invention is
A conductive solid substance and a thermoplastic resin are microscopically and homogeneously mixed, and it is possible to omit the kneading operation, but if necessary, the Banbury process, which is usually performed before the above molding process, may be necessary. Mixing operations may also be performed using a mixer, co-kneader, mixing roll, etc.
At that time and/or during the molding operation, in addition to plasticizers, stabilizers, crosslinking agents, flame retardants, etc., it is also possible to add modifiers that improve the adhesion between the 3g conductive solid material and the resin. It is.

(Function) In the conductive resin molding material of the present invention, since the conductive solid substance and thermoplastic resin are homogeneously mixed in a microscopic state, this conductive solid substance and thermoplastic resin are heated when manufacturing resin molded products. The conductive solid material and the thermoplastic resin do not become non-uniform, and even if the content of the conductive solid material is increased to a range of 50-99% by weight, the conductive solid material and the thermoplastic resin are always mixed uniformly. At the same time, it is considered that the surface of the conductive solid substance is maintained uniformly coated with the thermoplastic resin, and molding is possible.

〔Example〕

Example 1 Natural flaky graphite 1 with a particle size of 1 to 30 μm and an average particle size of 6 μm
0.00 M parts of cucumber were suspended in 350 parts by weight of water, 0.61 ff 1 part of cetyltrimethylammonium bromide, a cationic surfactant, was added thereto, and after stirring at room temperature for 10 minutes, the solid content was reduced to 29.0 M parts. 47 parts of 7ffifn% 7-ionic polyvinyl chloride latex was added under stirring, stirred roughly for 30 minutes, filtered, washed with water, and dried to form a graphite/polymer whose graphite surface was coated with polyvinyl chloride fine particles. 114 parts of vinyl chloride composite powder were obtained. At this time, the 'a solution was transparent, and the resin content of the obtained composite powder was 12.3% by weight.

The graphite/polyvinyl chloride composite powder thus obtained was kneaded as is or after kneaded at 140°C with a kneading roll, and then hot pressed at a press temperature of 145°C and a press pressure of 200 kg/ci to a thickness of 1rIR.
The molded material was molded into a sheet-like molded product, and its moldability and volume resistivity value by the four-probe method were investigated. The moldability during molding was good both when the graphite/polyvinyl chloride composite powder was molded as it was and when it was kneaded using a kneading roll. Furthermore, the volume resistivity value of the sheet-like molded product obtained after roll kneading was 0.08Ω.
The value of α was 0.05Ωα for those without roll kneading, and all exhibited excellent conductivity.

Example 2 Natural flaky graphite with a particle size of 1 to 150 μm and an average particle size of 55 μm was used, and polyvinyl chloride latex (solid content 29.7 ffiffi%) was added to 100 parts by weight of this graphite.
124 parts by weight of graphite/polyvinyl chloride composite powder with a resin content of 19.3% by weight was obtained in the same manner as in Example 1 using 81 parts by weight of melon.

This graphite/polyvinyl chloride composite powder was also investigated for its moldability and volume resistivity (po1) in the same manner as in Example 1.The results were as follows: The moldability during molding was also good when hot press molding was performed after kneading with a kneading roll.In addition, the volume resistivity value of the obtained sheet-shaped molded product was The conductivity was 0.23 Ωcm for the one that passed through the roll cross-connection, and 0.1 Ωcm for the one that did not pass through the roll cross-connection, and both exhibited excellent conductivity.

Comparative Example 1 The natural flaky graphite and powdered polyvinyl chloride resin used in Example 1 were blended to have the same resin content as the graphite/polyvinyl chloride composite powder obtained in Example 1, Kneading using a kneading roll was attempted. With this formulation, crosstalk by rolls was impossible, and a molding material could not be obtained.

In addition, when kneading the natural flaky graphite into hard polyvinyl chloride resin using a kneading roll, the graphite content is approximately 50m0.
%, and the volume resistivity of the molded product was 35Ω, making it impossible to obtain a molded product with high conductivity.

Comparative Example 2 The water content of the polyvinyl chloride latex used in the above example was removed to obtain a finely powdered polyvinyl chloride resin, and this and the natural flaky graphite used in the above example were added to the polyvinyl chloride resin obtained in Example 1. The resin content is the same as that of the graphite/polyvinyl chloride composite powder.
Mixed for 0 minutes. Although an attempt was made to mold this mixture by hot pressing, it was not possible to obtain a sheet-like molded product. Further, roll kneading of the above mixture was also impossible, and a molding material could not be obtained.

Example 3 93 fJm part of natural flaky graphite with an average particle size of 6 μm and aiI
lc length 10s long sword 0s fiber - 7 melon weight part 370f
The flfit portion was dispersed in water, and the solid content was 28% by weight.
After adding 28 weight parts of anionic polyvinyl chloride latex, 10 parts of aluminum nitrate was added, stirred for 10 minutes, filtered, washed with water and dried to obtain graphite with a resin content of 7.3%. 108ffljC parts of Carbon Fushivar/polyvinyl chloride composite powder were obtained. When this composite powder was used for hot press molding, the moldability was good, and the volume resistivity of the obtained sheet-shaped molded product was 0.04Ω.
It was cll+.

Example 4 Iooim parts of nickel powder were dispersed in a mixed solvent of 50fffi parts of ethanol and 150 m parts of water, and after adding 5 mm parts of an anionic latex of methyl methacrylate-butyl methacrylate copolymer with a solid content of 43fffffi%, 1.5 parts by weight of the cationic surfactant cetyltrimethylammonium bromide was added, stirred for 20 minutes, filtered, washed with water and ethanol, and the resin content was 1.
．． 3% nickel/methyl methacrylate/butyl methacrylate copolymer composite powder 101.3fiff1
I got the department. A sheet-like molded body was obtained by hot press molding this composite powder. The volume resistivity value of the obtained molded body was 2.0×10′Ωα.

〔Effect of the invention〕

According to the present invention, in addition to providing a conductive resin molding material that not only has high conductivity but also good moldability, it also provides a manufacturing method that can be manufactured by a simple method and in a short time. It is of extremely high value.

Claims (7)

[Claims] (1) A conductive resin molding material characterized in that a thermoplastic resin aggregated from thermoplastic resin latex is attached to a conductive solid substance. (2) The conductive resin molding material according to claim 1, wherein the content of the conductive solid substance is 50 to 99% by weight. (3) A conductive resin characterized by mixing a conductive solid substance and a thermoplastic resin latex to prepare a mixed latex, and then destroying the mixed latex to aggregate the conductive solid substance and the polymer fine particles in the latex. Method of manufacturing molding material. (4) The method for producing a conductive resin molding material according to claim 3, wherein the mixed latex is broken by adding a latex breaking agent. (5) The method for producing a conductive resin molding material according to claim 3, wherein the mixed latex is destroyed by means of destabilizing the latex, such as freezing. (6) A charge imparting substance is added to an aqueous medium dispersion of a conductive solid substance, and then a thermoplastic resin latex having an opposite charge is mixed with the charge imparting substance to heterogeneize the conductive solid substance and polymer fine particles in the latex. A method for producing a conductive resin molding material, which comprises aggregating the material. (7) The charge imparting substance is an electrolyte having a potential determining ion of a conductive solid substance, a polyvalent cation electrolyte, a polyvalent anion electrolyte, a cationic surfactant, an anionic surfactant, a cationic polymer electrolyte, and 7. The method for producing a conductive resin molding material according to claim 6, wherein the material is at least one substance selected from the group consisting of anionic polymer electrolytes.