JPH0456403B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a filler used in a conductive composite material, a conductive composite material that utilizes the characteristics of the filler, and a conductive coating material. Conventional technology Conventionally, composite materials made by blending conductive carbon black or graphite particles with rubber or polymer resin have been produced in various forms such as sheets, films, molded bodies, and even paints and pastes. It is used in a wide range of applications as a conductivity-imparting material to impart conductivity to transport cases and packaging materials for electrical protection, heating heaters, pressure switches, pressure-sensitive conductive rubber, radio wave shielding materials, ICs, etc. However, the specific resistance value of the above-mentioned transport case and packaging material, etc.
In order to provide conductivity of approximately 10 ⁰ to 10 ^-2 Ω・cm, approximately 10 to 30% by weight of the above carbon black particles is required.
It is necessary to blend a large amount of. However, blending a large amount of carbon black particles leads to high costs, and when kneaded with a polymer resin etc., the viscosity suddenly increases, making processing and molding difficult. Therefore, there has been a demand for the development of a composite material that can exhibit higher conductivity than conventional materials by incorporating a small amount of carbon black or graphite particles. In view of the above-mentioned situation, in recent years, conductive composite materials have been developed using resins made of propylene polymer and ethylene polymer, metal oxides such as Fe, Zn, Ti, Al, etc., inorganic oxides such as silica, quicklime, etc. Al(OH) ₃ ,
Metal hydroxides such as Mg(OH) ₂ , Ca(OH) ₂ ,
Carbon per 100 parts by weight of the base containing inorganic salts such as MgCO ₃ , CaCO ₃ , BaSO ₄ , CaSO ₄ , CaSiO _{2 ,} etc., and an inorganic filler selected from the group of clay, glass beads, shirasu, silica sand, etc. Conductive resin compositions containing 2 to 100 parts by weight of black (Japanese Patent Application Laid-open No. 57-21441) and conductive resin compositions containing carbon black coated with a titanate coupling agent (Japanese Patent Laid-Open No. 57-21441). 149356) has been proposed. Furthermore, as a conductive coating material, a conductive undercoat composition (Japanese Patent Laid-Open No. 167658/1983) has been proposed, which uses a thermoplastic resin mixed with conductive carbon black and titanium oxide. Problems to be Solved by the Invention The present inventors have studied fillers that can exhibit excellent conductivity by incorporating a small amount of carbon black or graphite from a different perspective from the above-mentioned proposed techniques. Contains iron oxide and silica in specific ranges, and
nFeO・SiO ₂ or nFeO・Fe ₂ O ₃・SiO ₂ (n is 1 to
Knowledge that inorganic oxides that exist in the form of (an integer of 3) and have a small composition in which the content of alkali metal oxides or alkaline earth metal oxides is below a certain amount can be used as fillers having the above characteristics. As a result, the present invention was completed. Therefore, by using the above-mentioned inorganic oxide as a filler, the present invention has excellent electrical conductivity, sound absorption, and flexibility even with a small amount of carbon black particles or graphite particles. The objective of the present invention is to provide a composite material with excellent properties and mechanical strength. The present invention will be explained in detail below. Structure of the Invention The present invention is characterized by a composition containing 50 to 90% by weight of iron oxide and 10 to 40% by weight of silica, and a total content of each alkali or alkaline earth metal oxide of 10% by weight or less. A filler for conductive composite materials comprising 0.3 to 20 parts by weight of carbon black particles and/or graphite particles to 100 parts by weight of inorganic oxide particles having A conductive composite material is prepared by blending 20 to 100 parts by weight of a substance and kneading and molding the mixture, and blending the above filler with 20 to 150 parts by weight of an organic polymeric substance having binding properties, and adding a solvent to this. It is made of conductive coating material. Means for Solving the Problems The inorganic oxide used in the filler according to the present invention is
As mentioned above, it contains iron oxide and silica in a specific range of ratios, and the main components of iron oxide include FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , nFeO・SiO _{2 and} nFeO・It may be in any form of Fe ₂ O ₃ · SiO ₂ (n is an integer from 1 to 3), but at least 50
% by weight, preferably 60% by weight is nFeO SiO ₂ or
The form of nFeO.Fe ₂ O _{3.SiO 2} is desirable from the viewpoint of improving workability and sound absorption. Furthermore, if the content of iron oxide in the filler is less than 50% by weight, the sound absorption properties will be insufficient. On the other hand, silica, which is another essential component, has an extremely excellent effect in increasing the amount of iron oxide that can be filled into the composite material. Even if the thickness is increased, the flexibility of the resulting composite sheet, etc. is maintained. However, since silica has a lower bulk density than iron oxide, its presence in large amounts is not desirable;
A suitable content is 40% by weight, preferably 10 to 30% by weight. In addition, silica is SiO ₂ , nFeO・
It may be in any form of SiO ₂ , nFeO.Fe ₂ O ₃ .SiO ₂ or silica alumina. The inorganic oxide used in the filler of the present invention is not particularly limited in terms of components other than the above-mentioned essential components, but each alkali or alkaline earth metal oxide,
For example, the total content of Na ₂ O, MgO, and CaO must be 10% by weight or less, preferably 5% by weight or less. When the content of these metal oxides increases, moldability is significantly reduced. That is, the surface smoothness of the composite sheet decreases due to the prolongation of the gelation time and the plate-out phenomenon. The filler of the present invention is made by blending 0.3 to 20 parts by weight of carbon black and/or graphite particles as a conductive component to 100 parts by weight of the above inorganic oxide. Iron concentrate slag particles produced in the copper smelting process as described below can be used as the iron concentrate slag particles. This iron concentrate slag is produced by oxidizing silicate and oxidizing matte obtained from a flash furnace in a converter while adding SiO ₂ and oxygen, magnetically separating the resulting slag, and then flotation to recover copper concentrate. It is obtained by dehydrating the residue after washing. The iron concentrate slag thus obtained has the following composition. 2FeO・_SiO2 (40~50wt% as FeO, _SiO2
15-30wt%) ......50-85wt% Fe ₃ O ₄ ......10-30wt% Fe ₂ O ₃ ......2-10wt% MgO ......5wt% or less CaO ......0 In other words, the above As seen in the composition, the above-mentioned iron concentrate slag fully satisfies the compositional requirements of the inorganic oxide, and in addition, the particle size is small and it has excellent affinity with resin, so it can be used in the present invention. It can be effectively used as an inorganic oxide in fillers. When using iron concentrate slag, the water content should be 2% by weight or less, preferably 1% by weight or less, especially
Use after drying to 0.5% by weight or less. The blending ratio of the inorganic oxide and the carbon black particles and/or graphite particles in the filler of the present invention is as described above, and the blending amount of the carbon black particles and/or graphite particles is per 100 parts by weight of the inorganic oxide. If it is less than 0.3 parts by weight, no effect of improving conductivity can be expected, while if it exceeds 20 parts by weight, although conductivity improves, it becomes difficult to knead, and the mechanical strength of conductive sheets and films obtained using fillers decreases. It becomes significantly weaker and becomes easily cut by bending force. The above-mentioned amount of carbon black particles and/or graphite particles is preferably 3 to 15 parts by weight. Examples of the carbon black particles used here include acetylene black, furnace black, etc., which have been conventionally used in conductive fillers, but ketchen black is particularly preferred from the viewpoint of improving conductivity. Further, carbon black particles and graphite particles may be mixed with an inorganic oxide at the time of use, or may be mixed separately with a resin or the like. Next, a conductive composite material using the above filler will be explained. The conductive composite material of the present invention is obtained by blending a mixture of the above-mentioned inorganic oxide and carbon black particles and/or graphite particles (hereinafter referred to as a composite) with an organic polymer substance. The organic polymeric substance used here acts as a binder to bind the filler, and examples of such substances include natural rubber, butyl rubber, butadiene rubber, silicone rubber, vinyl chloride resin, vinyl acetate copolymer, and ethylene. - Vinyl acetate resin, polyethylene, phenolic resin, polyester resin, etc. may be exemplified. For conductive coating materials, resins such as epoxy resins and urethane resins that form a film by drying and heating after coating are used. In addition, appropriate plasticity, stabilizers,
A lubricant or the like may be mixed and used. In the composite material of the present invention, 200 to 800 parts by weight of inorganic oxide particles, carbon black particles and/or
Alternatively, a filler consisting of 2 to 10 parts by weight of graphite particles is blended and kneaded, and the resulting product is molded into a sheet or film for use as a conductive material, or a solvent is added to the kneaded product. It is used as a conductive coating material. The conductive composite material of the present invention is usually about 2.0 to 2.8 iron oxide per mm of thickness, depending on the amount of iron oxide filled into it.
It has a high areal density of Kg/ ^m2 , and also has good flexibility and excellent mechanical strength. Regarding electrical conductivity, for example, a conventional composite material filled with a filler containing only 5% by weight of KETSUCHEN BLACK EC has a resistance of 10 ⁴ to ^{10 7} Ω・cm, whereas a composite material containing the above-mentioned inorganic oxide has a resistance of 10 4 to 10 7 Ω・cm. The filler-filled composite of the invention has a resistance of 10 ² to ^{10 0} Ω·cm. That is, the above-mentioned excellent functions of the composite material according to the present invention can be attributed to the synergistic effect of the inorganic oxide and carbon black or graphite in the filler according to the present invention. EXAMPLES The present invention and its effects will be explained in more detail with reference to Examples below. Examples and Effect Examples Inorganic oxide powders and carbon black particles (trade name: KETSUCHEN BLACK) with various compositions shown in Table 1
EC) at each compounding ratio shown in Table 2, a resin consisting of 100 parts by weight of vinyl chloride resin (average degree of polymerization 800), 60 parts by weight of dioctyl phthalate as a plasticizer, 1 part by weight of lead soap, and 5 parts by weight of a stabilizer. It was mixed into a compound and kneaded. Each of the obtained kneaded products was heated to 130° C. using a two-roll molding machine with a diameter of 8 inches and a width of 20 inches to produce sheets with a thickness of 0.8 mm. The moldability and performance of each sheet obtained are also shown in Table 2. Note that the volume resistivity value was calculated by the following formula by cutting the obtained sheet into a test piece having a length of 11.2 cm and a width of 5.0 cm, applying electricity to both ends in the length direction, measuring the electrical resistance ρ. Volume resistance value (Ω・cm) = ρ×thickness×width/length

【table】

[Table] As shown in Table 2, those using F-1 according to the present invention as an inorganic oxide (No. 1, 5, 6, 7
and 10), the gelation time during sheet forming process is
It is as short as 45 seconds, and there is no plate-out phenomenon to the roll, and the surface gloss of the sheet is good. However, in No. 6, which does not contain carbon black as a filler, the volume resistivity is extremely high and the conductivity deteriorates, but in No. 1, 5, and 7 according to the present invention, a small amount of 3 to 5 parts by weight of carbon black is mixed. However, the volume resistivity is reduced. In addition, No. 1 contains 10 parts by weight of carbon black.
10, the above resistance becomes 10 ⁰ Ω·cm or less. In contrast, comparative examples (No. 2,
In the case of 3 and 4), the gelation time during the sheet forming process is twice as long as that of the present invention, and moreover, the plate-out phenomenon occurs severely on the roll surface. On the other hand, without blending the inorganic oxide according to the present invention,
In Reference Examples Nos. 8 and 9) in which only carbon black was used as a filler, when the same amount of carbon black was blended, it was found that the volume resistivity was higher and the conductivity was significantly lower than that of the present invention. As described above, the composite sheet obtained using the filler of the present invention has good moldability, maintains sheet flexibility, has a high areal density, and has a reduced resistance value. It can be said that it has excellent conductivity.

Claims (1)

[Claims] 1 (a) 50-90% by weight of iron oxide and 10-40% by weight of silica
(b) carbon black particles and/or A filler for conductive composite materials, characterized in that it contains 0.3 to 20 parts by weight of graphite particles. 2. The method according to claim 1, wherein all or 50% by weight or more of the iron oxide and silica are present in the form of nFeO.SiO ₂ or nFeO.Fe ₂ O _{3.SiO 2} (n is an integer from 1 to 3). Filler for conductive composite materials. 3. The filler for conductive composite materials according to claim 1, wherein the total content of alkali metal oxides or alkaline earth metal oxides is 5% by weight or less. 4 (a) Iron oxide 50-90% by weight and silica 10-40% by weight
per 100 parts by weight of inorganic oxide particles containing a composition in which the total content of alkali metal oxides or alkaline earth metal oxides is 10% by weight or less,
(b) a filler containing 0.3 to 20 parts by weight of carbon black particles and/or graphite particles;
A conductive composite material made by mixing and kneading 20 to 100 parts by weight of an organic polymer substance with binding properties. 5 All or 50% by weight of iron oxide and silica
The above is nFeO・SiO ₂ or nFeO・Fe ₂ O ₃・SiO ₂ (n
is an integer from 1 to 3). The conductive composite material according to claim 4, wherein: 6. The conductive composite material according to claim 4, wherein the total content of alkali metal oxides or alkaline earth metal oxides is 5% by weight or less. 7 (a) Iron oxide 50-90% by weight and silica 10-40% by weight
carbon black particles and/or graphite particles per 100 parts by weight of inorganic oxide particles having a composition in which the total content of alkali metal oxides or alkaline earth metal oxides is 10% by weight or less.
A conductive coating material obtained by blending 0.3 to 10 parts by weight of a filler with (b) 20 to 150 parts by weight of an organic polymer substance having binding properties, and (c) adding a solvent to the blend. .