JPS62260800A - Magnetic electrically-conductive substance - Google Patents

Abstract

PURPOSE:To produce magnetic electrically-conductive substance showing electrical conductivity, magnetic properties and improved reinforcing properties, by adding an aqueous solution of iron salt to water dispersion of electrically- conductive fibrous substance and carrying out hydrolysis to deposit an iron oxide magnetic component on the electrically conductive fibrous substance. CONSTITUTION:An electrically conductive fibrous substance (electrically conductive alkali titanate) is dispersed into water in concentration of about 70-0.1vol% and an aqueous solution of an iron salt (iron chloride, iron sulfate, etc.) is added to the water dispersion. Then, a magnetic component of iron oxide type (ferrite compound, etc.) is deposited on the electrically conductive fibrous substance by hydrolysis or oxidation under heating. Consequently, magnetic electrically- conductive composite compound is simply produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic conductive material in which the surface of a conductive fiber material is coated with a magnetic material, and a method for producing the same.

The magnetic conductive substance of the present invention has a fine fiber shape and is both conductive and magnetic, and is useful as a material for electromagnetic shielding composite materials, a material for functional composite materials, and the like.

(Conventional technology) In response to the development of chemical technology and the diversification of needs, the development of high-performance and highly functional materials is actively being carried out, and even in the plastics industry, various research is being conducted on conductive polymer materials. For example, carbon particles, carbon fiber, copper,
Metal powders such as silver and aluminum have been proposed. Ikegata: Magnetic materials include magnetic metal powders such as metals such as iron, nickel, chromium, and cobalt, and their alloys, high magnetic permeability powders such as ferrite, and high coercive force powders such as barium ferrite. However, all of these exhibit either conductive or magnetic properties, and few of them can exhibit a reinforcing effect when used as a mating material. However, in recent years, high precision electronic components,
As quality increases, so-called electromagnetic interference occurs, which causes malfunctions due to external electromagnetic waves, etc., and the development of electromagnetic shielding materials to prevent this is desired, and electromagnetic wave absorbing materials are used as materials that can be applied to these. Generally, metal materials with excellent conductivity are used.

However, these metal materials have poor moldability, aesthetic properties, and f! There are various problems in terms of quantification, etc., and it has been desired to develop a material that can be mixed into plastics etc. with excellent moldability and that also exhibits an electromagnetic shielding effect. The various conductive powders mentioned above have been used as such materials, but all of these are non-reinforcing materials. still,
The present inventor has developed various fibrous conductive titanates as conductive reinforcing materials, but with the recent trend towards higher precision and higher integration of electronic components, simply having high conductivity is not enough to reduce electromagnetic waves. However, the absorption of the magnetic properties of the reinforcing material is insufficient, and it has been desired to develop a reinforcing material that is both highly conductive and magnetic.

(Problems to be Solved by the Invention) An object of the present invention is to provide a magnetic conductive material which is a fibrous material exhibiting both conductivity and magnetism and excellent reinforcing properties, and a method for producing the same.

Further, the purpose of the present invention is to improve molding processability, surface smoothness of molded products,
The object of the present invention is to provide a magnetic conductive material that can give molded products with excellent abrasive properties.

(Means for Solving the Problems) The present invention relates to a magnetic conductive material in which the surface of a conductive fiber material is coated with a magnetic material, and a method for producing the same.

The electrically conductive fiber material that serves as the base material in the present invention has a volume specific resistivity (hereinafter referred to as ρV) measured under a pressure of 100 kg/cm2 and a force bow Q + 2Ωelf.
i or less is preferable, and the lower limit is not particularly defined, but currently 1
Approximately 0-5Ωcf11 is preferable. Furthermore, fibrous material is defined as a material having a spectral ratio (length/diameter ratio) of 7 or more, and as is clear from the definition of fibrous material, there is no particular upper limit. However, #a is strictly determined depending on the purpose of use of the fiber material, and when used as a fiber-reinforced composite material in the narrow sense or as a fabric, long fibers are desired, but reinforcement may be used instead of ordinary fillers. When used as a filler, the α to 7 spectral ratio is 10 to 1000 in terms of moldability etc.
, preferably about 10 to 300, and those generally called fine fibers or whiskers are preferred. In the present invention, any known conductive fiber material can be used, such as conductive carbon fiber,
Examples include conductive polymer fibers, conductive metal fibers, conductive ceramic fibers, and various other non-porous conductive fibers. Representative examples of these include carbon fibers, polyacetylene fibers, aluminum fibers Mt, nickel fibers ML, carbide fiber,
Nitride NiL fiber, boride NI1. m, conductive zinc oxide type IyL4 (i, conductive treated aluminum oxide fiber, conductive treated gypsum YL navy blue, conductive alkali titanate fiber, etc. 07
The proposed conductive alkali titanate 1Jii is suitable because of its stable conductivity, heat resistance, reinforcing properties, moldability, surface smoothness, etc.

The magnetic substance of the present invention is a paramagnetic substance, a ferromagnetic substance, etc., and these are selected depending on the purpose of use, and any substance can be selected. However, when used as a shielding material, magnetic properties such as magnetic memory elements, For electronic components that utilize the magnetic conductive material of the present invention, it is necessary to suppress the magnetic force to a range that is not affected by the magnetic force of the magnetic conductive material of the present invention and the magnetic force excited by an external magnetic field.
On the other hand, when the composite material made of the magnetically conductive material of the present invention is used for storage elements, electromagnetic circuits, etc., the desired magnetism is required.

Typical examples of the magnetic materials of the present invention include γ-Fe, O
,,MnFe2O,,NiFe2O,,CoFe:O,
.

Ferrite compounds such as Ba0.6 Fe203 and iron oxide compounds such as magnetite, Fe, Ni+ C
r.

These include metals such as Co and alloys thereof, and may be one kind or a mixture of two or more kinds thereof. Magnetite (Fe
30-) is a substance that exhibits both magnetism and conductivity, and when a coating layer is made of a substance that exhibits both magnetism and conductivity, even if a slightly discontinuous layer is formed in the magnetic wave Ffi layer, It has the advantage of not having much effect on magnetism and conductivity.

In addition, methods for coating the surface of conductive fiber materials with these magnetic substances include wet chemical reaction and vapor phase chemical reaction (CVD).
Although the reaction can be carried out by any method such as PVD, sputtering, etc., it is preferable to carry out by wet chemical reaction from the viewpoint of easy work process and process control.

The conductive magnetic material of the present invention can be produced by adding an aqueous iron salt solution to an aqueous dispersion of a conductive fiber material, and then hydrolyzing or heating the iron salt to oxidize the iron oxide magnetic component to the conductive fiber material. It can be produced by depositing it on the surface of. In the present invention, iron salts are iron-based compounds that are soluble or maintain a stable colloidal dispersion system in neutral or acidic aqueous solutions and water-soluble solvents, including iron chloride, iron sulfate, iron nitrate, and water. Examples include various iron salts such as iron oxide, iron carbonate, and organic iron salts.

The present invention can be produced by a method in which the above-mentioned iron salt is deposited as an iron oxide fan magnetic component on the surface of a conductive i-fiber material,
A specific method for depositing is to add an iron salt solution to an aqueous dispersion of conductive fiber material and hydrolyze it. After dissolving or dispersing a hydrolyzing agent in an aqueous dispersion of conductive fiber material, iron salt The method of adding a solution is simple, and the solution of the hydrolyzing agent and the solution of the iron salt may be added simultaneously or alternately to the dispersion of the conductive fiber material. The most effective method is to deposit the iron oxide-based magnetic material directly onto the surface of the conductive fiber material by keeping it in an atmosphere that promotes hydrolysis, such as by heating or aeration. may be deposited and then oxidized by heating or the like to change into an iron-based compound exhibiting magnetism.

All of the above-mentioned reactions proceed by known reactions, but in an aqueous dispersion system of conductive fibers, the concentration of the conductive fibers should be limited to an area that can be stirred or kneaded with a mixer, and is usually 70 vol. % or less, and the lower limit is preferably a range in which economic efficiency and deposits are effectively deposited on the surface of the conductive m-fiber material, that is, 0.1 ν01% or more; if outside these ranges, the economic efficiency disappears or Even when used as a composite material, no significant difference is often observed.

In the present invention, an iron salt solution is added to an aqueous dispersion of conductive 11 vertebrae material for hydrolysis, but the most effective method is to add an iron salt solution in the presence of a hydrolyzing agent. Examples include lithium, potassium, sodium, calcium,
Salts of alkali or alkaline earth metals such as magnesium, barium, strontium, etc. are effective.

In the present invention, the conditions for each step may be selected depending on the purpose of use, the iron salt used, the type of conductive fiber material, etc. For example, the molar ratio of the iron salt solution and the neutralizing agent is approximately the same, the neutralizing agent/iron salt;
0.05 or more is required, less than 0.05 is 50'
It is necessary to perform sufficient heating or aeration to a temperature higher than C, and conversely, if the temperature exceeds 10, it tends to be difficult to deposit iron salts, so it is usually in the range of 0.1 to 8, preferably 0.7 to 6. It is preferable to maintain the reaction system at a temperature of 50'C or higher.

Note that the present invention does not limit the addition or combined use of commonly used dispersion stabilizers, surfactants, sedimentation control agents, magnetic improvers, and the like.

(Example) A detailed explanation will be given below with reference to examples.

Example 1 Conductivity t! J, fibrous potassium titanate (Otsuka': r-
40 ml of water
and stirred for 5 minutes using a stirrer. Next, while continuing to stir this dispersion, the temperature was raised to 80°C, and under heating, 33.5+ nl of a 1 mol/l ferrous chloride aqueous solution, 67+ ol of a 1 mol/l ferric chloride aqueous solution, and 3.7 ml of a 1 mol/l ferric chloride aqueous solution were added. After adding 63+nl of an aqueous solution of 17 um (specified hydroxide) at a uniform rate so that each solution was added dropwise in 30 minutes, the mixture was further heated at 80°
The precipitate was aged for 2 hours at C, and the precipitate was separated, washed with water, and dried to obtain 12.5 g of a dark brown, ferromagnetic, slightly auWL fibrous magnetic conductive material. The volume resistivity of this magnetic conductive material is 4. 1XIO3Ωel11, and the volume resistivity of Quistat B K-100 used as a raw material (4.3X 105ΩCm) No change was observed.

Example 2 By carrying out the same method as in Example 1 except that 5 g of conductive fibrous potassium titanate (Otsuka Chemical Co., Ltd., Rice Tara BK-200) was used, fine I
a. Obtain 12.3 g of fibrous magnetic conductive material.

The volume resistivity of this magnetic conductive material is S, 3×10−
1Ωcan, and Quistat BK was used as a raw material.
-200 volume resistance IF (1,03Xlo°Ωcoo)
It was even better.

Example 3 Conductive fibrous potassium titanate (Quistat B K-
200) 1 mol/after dispersing 5 g in water 200+111
After adding ferrous sulfate aqueous solution fL65 +n l of 1, hydroxide to 3.7N with stirring) l) Rum aqueous solution 25! f
After approximately 15 minutes of addition, the liquid temperature was raised to 80°C, a nozzle connected to an air pump was introduced into the reaction system, and cleaning air was introduced at a flow rate of 31/min for 1 hour. After oxidizing the reactant while stirring with bubbles, the mixture was separated, washed with water, and dried to obtain 7.5 g of a dark brown, ferromagnetic fine fiber magnetic conductive material L. The volume resistivity of the obtained magnetic conductive material is 6.2X10-'ΩCI
It was a.

Example 4 In Example 3, 25+nl of a 3.7N aqueous solution of sodium hydroxide was added to 20ml, and the reaction temperature was set to [30'(
:1. The same method was followed except that 19 g of a dark brown, ferromagnetic fine fiber magnetic conductive material was obtained. The volume resistivity of the obtained magnetic conductive material is 1.7X 10
-'ΩCτ0.

Example 5 The same method as in Example 4 was used except that the conductive potassium titanate was changed to 5 g of carbon fiber fine powder (am 3r old o), and a fine YL miscellaneous magnetic conductive material having dark brown color and ferromagnetic properties was obtained. 18 g of material was obtained. The specific volume resistivity of the obtained magnetic conductive material is similar to that of the carbon fiber fine powder used as the raw material.
Denotal Electro Switcher TR manufactured by Takegu Uken Co., Ltd.
It was a material with good conductivity below the measurement limit of 6841 (10-'Ωcan).

(Effects of the Invention) The magnetic conductive substance of the present invention does not reduce the properties of the conductive fiber material used as the base material for composite materials, such as reinforcing properties, heat resistance, surface smoothness, moldability, etc. It is a functional composite material material that can impart conductivity and magnetism, and is extremely suitable for providing magnetic conductive composite materials, and its manufacturing method is extremely simple and has high industrial applicability. be.

(that's all)

Claims (4)

[Claims] (1) A magnetic conductive material in which the surface of a conductive fiber material is coated with a magnetic material. (2) The magnetic conductive material according to claim 1, wherein the conductive fiber material is a conductive alkali titanate. (3) Production of a magnetic conductive material characterized by adding an aqueous iron salt solution to an aqueous dispersion of a conductive fiber material and subjecting it to hydrolysis or thermal oxidation to deposit an iron oxide-based magnetic component onto the conductive fiber material. Law. (4) The method for producing a magnetic conductive material according to claim 3, wherein the conductive fiber material is a conductive alkali titanate and the iron oxide magnetic component is a ferrite compound.