JP2589472B2 - Magnetic substance - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic substance having a fibrous substance whose surface is coated with an iron oxide-based magnetic substance, and a method for producing the same. The magnetic substance of the present invention shows a fine fiber shape and has excellent reinforcing properties such as plastics, and is a material for magnetic composite materials,
It is useful as a material for functional composite materials.

(Conventional technology) With the development of chemical technology and diversification of needs, high performance,
Active development of high-performance materials has been actively carried out. Examples of magnetic materials include magnetic metals such as iron, nickel, chromium, and cobalt and alloys thereof, magnetically permeable powders represented by ferrite, barium ferrite, and the like. Although high coercive force powders and the like represented by are known, none of them can exert a reinforcing effect when used as a composite material. However, in recent years, with the increase in precision and quality of electronic components, there has been a demand for the development of precision composite materials that exhibit high precision, high strength, and high magnetism. However, in order to achieve high magnetic properties, it is necessary to fill a large amount of these magnetic powders. This has made the development of composite materials difficult.

(Problems to be Solved by the Invention) An object of the present invention is to provide a magnetic material having excellent surface smoothness, high strength and high magnetism and having a fiber shape as a material for a magnetic composite material, and a method for producing the same. It is in.

(Means for Solving the Problems) The present invention relates to a magnetic material in which the surface of an alkali titanate fiber having an aspect ratio of 10 to 300 is coated with an iron oxide-based magnetic material and a method for producing the same.

In the present invention, the fibrous material serving as the base material has an aspect ratio (length / diameter ratio) of 10 or more, and the upper limit is not particularly defined as is apparent from the definition of the fibrous material. However, it is strictly determined according to the purpose of use of these fibrous substances. When used as a fiber reinforced composite material in a narrow sense or as a fabric, a long fiber is desired, but a reinforcing filler is used instead of a normal filler. When used as, the aspect ratio is from 10 to 1000, preferably from 10 to 30 from the viewpoint of moldability and the like.
The thing of about 0 is good, and what is generally called fine fiber or whisker is preferable. In the present invention, as the fiber substance, any known substances can be used, and as such a substance, glass fiber, alumina fiber, calcium sulfate fiber,
Examples include rock wool, calcium silicate fiber, asbestos, silicon carbide fiber, silicon nitride fiber, and alkali titanate fiber. Among these, alkali titanate fibers are preferable, and in particular, alkali metal titanate having a composition represented by the general formula M ₂ O · nTiO ₂ (where M represents an alkali metal and n represents an integer of 2 to 12), For example, sodium titanate, potassium titanate, lithium titanate and the like are preferable. Further, potassium titanate fiber has excellent heat resistance and mechanical strength, and when used as a filler, has excellent surface smoothness and reinforcing property. In that it is particularly advantageous.

The iron oxide-based magnetic substance of the present invention is a paramagnetic substance, a ferromagnetic substance, and the like, which are selected according to the purpose of use, and any one is selected.
Ferrite compounds such as ₂ O ₃ , MnFe ₂ O ₃ , NiFe ₂ O ₄ , CoFe ₂ O ₄ , BaO.6Fe ₂ O ₃ and iron oxide compounds such as magnetite, and one or more of these compounds A mixture may be used. Magnetite (Fe ₃ O ₄ ), which is defined as spinel-type ferrite as one type of magnetic substance, is a substance that exhibits conductivity simultaneously with magnetism. Such a substance that exhibits both magnetism and conductivity is used as a coating layer. At the time, it becomes a magnetic conductive material and is suitable as a material for a highly functional composite material.

The magnetic material can be coated on the surface of the fiber material by any method such as wet chemical reaction, gas phase chemical reaction (CVD), vapor deposition method (PVD), and sputtering. It is preferable to carry out by a wet chemical reaction from the viewpoint of easy process and process control.

The magnetic substance of the present invention is to deposit an iron oxide-based magnetic component on the surface of the fibrous substance by, for example, adding an aqueous solution of an iron salt to an aqueous dispersion of the fibrous substance and subjecting the iron salt to, for example, hydrolysis or thermal oxidation. Can be manufactured. In the present invention, an iron salt is an iron compound that retains a soluble or stable colloidal dispersion in a neutral or acidic aqueous solution and a water-soluble solvent, and includes iron chloride, iron sulfate, iron nitrate, iron hydroxide, Various iron salts such as iron carbonate and organic iron salts are exemplified.

The present invention can be produced by a method of depositing the above-described iron salt on the surface of the fiber substance as an iron oxide-based magnetic component.As a specific method of depositing, an iron salt solution is dispersed in an aqueous dispersion of the fiber substance. A method of adding and hydrolyzing or dissolving or dispersing a hydrolyzing agent in an aqueous dispersion of a fibrous substance and then adding an iron salt solution is more convenient. The iron salt solution may be added simultaneously or alternately, and furthermore, at the time of hydrolysis, heating or holding in an atmosphere that promotes hydrolysis such as air-rate, etc., and the iron oxide-based magnetic material is directly applied to the surface of the fiber material. Although it is most effective to deposit the iron-based compound, the iron-based compound may be deposited on the surface of the fibrous substance and then oxidized by heating or the like to change to a ferrous compound exhibiting magnetism.

All of the above-mentioned reactions proceed by a known reaction.However, in the case of the water-dispersed yarn of the fibrous substance, the concentration of the fibrous substance should usually be limited to a region capable of being stirred or kneaded by a mixer, and usually 70 vo
l% or less is preferred, and the lower limit is preferably the economy and the range in which the sediment is effectively deposited on the surface of the fibrous material, that is, 0.1 vol% or more. Make control difficult.

In the present invention, a method of adding a solution of an iron salt to an aqueous dispersion of a fiber substance and performing hydrolysis, or a method of adding an iron salt solution in the presence of a hydrolyzing agent is most effective.
Salts of alkali or alkaline earth metals such as lithium, potassium, sodium, calcium, magnesium, barium, strontium and the like are effective.

In the present invention, the conditions of each step may be selected depending on the purpose of use and the type of the iron salt to be used, the type of the fiber substance, and the like. For example, the molar ratio of the iron salt solution and the neutralizing agent is approximately, and 0.05
The above is necessary, and if it is less than 0.05, even if the conditions for generating the desired magnetic substance, that is, the oxidation promoting conditions such as the reaction temperature and the aeration, are precisely controlled, products having no magnetism are likely to be mixed. If the temperature exceeds the above range, the precipitation of the iron salt tends to be difficult. Therefore, it is usually in the range of 0.1 to 8, preferably 0.7 to 6, and the reaction system is preferably maintained at 50 ° C. or higher.

In the present invention, addition and use of commonly used dispersion stabilizers, surfactants, sedimentation regulators, magnetic improvers, and the like are not limited.

(Example) Hereinafter, an example will be described in detail.

Example 1 Fibrous potassium titanate (Teismo D, manufactured by Otsuka Chemical Co., Ltd.)
5 g was dispersed in 40 ml of water and stirred with a stirrer for 5 minutes. Then, while continuing to stir the dispersion, the temperature was raised to 80 ° C., and 33.5 ml of a 1 mol / l ferrous chloride aqueous solution, 1 ml / l 67 ml of a 1 mol / l ferric chloride aqueous solution and 3.7 N water were added under heating. 63 ml of an aqueous solution of sodium oxide was added at a constant speed so that each solution was added dropwise in 30 minutes. The solution was aged at 80 ° C for 2 hours, and the precipitate was separated, washed with water and dried to obtain a dark brown ferromagnetic substance. As a result, 12.1 g of a fine fibrous magnetic material was obtained.

Example 2 Fibrous potassium titanate (Teismo L, manufactured by Otsuka Chemical Co., Ltd.)
By performing the same method as in Example 1 except that 5 g was used, 12.4 g of a dark brown, ferromagnetic fine fibrous magnetic material was obtained.

Example 3 5 g of fibrous potassium titanate (Teismo L) was added to 200 ml of water.
After dispersing in the solution, add 140 ml of 1 mol / l ferrous sulfate aqueous solution, add 55 ml of 3.7 N sodium hydroxide aqueous solution with stirring for about 15 minutes, and then raise the liquid temperature to 80 ° C. A nozzle connected to an air pump was introduced into the reaction system, washing air was introduced at a flow rate of 3 l / min for 1 hour, and the reactants were oxidized at the same time as the bubbles were stirred. 17.4g of a fine fibrous magnetic substance showing brown ferromagnetism
I got

Example 4 A fine fibrous magnetic substance showing dark brown ferromagnetism was prepared in the same manner as in Example 3, except that 55 ml of an aqueous solution of 3.7 N sodium hydroxide was changed to 20 ml and the temperature during the reaction was changed to 60 ° C.
18.5 g was obtained.

Example 5 The procedure of Example 3 was repeated, except that potassium titanate was changed to 5 g of silicon carbide whiskers (manufactured by Tokai Carbon Co., Ltd., Toka Matsukus), to obtain 16.8 g of a fine brown-colored magnetic material having a dark brown ferromagnetism. Was.

(Effect of the Invention) The magnetic substance of the present invention is a functional material that can be applied without any reduction in the material properties for a composite material of a fiber material as a base material, that is, reinforcing properties, heat resistance, surface smoothness, moldability, and the like. It is a material for a composite material, which is extremely suitable for providing a magnetic composite material, and its production method is also extremely simple and has high industrial applicability.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayoshi Suzue 463 Kagasuno, Kawauchi-cho, Tokushima City Inside Otsuka Chemical Co., Ltd. In the Tokushima Plant (56) References JP-A-57-103204 (JP, A) JP-A-59-141298 (JP, A) JP-A-58-192201 (JP, A) JP-A-60-12606 (JP, A A)

Claims (3)

(57) [Claims] 1. A magnetic substance wherein the surface of alkali titanate fibers having an aspect ratio of 10 to 300 is coated with an iron oxide-based magnetic substance. 2. An iron salt aqueous solution is added to an aqueous dispersion of alkali titanate fibers having an aspect ratio of 10 to 300, which is hydrolyzed or heated and oxidized to deposit an iron oxide-based magnetic component on the fibrous material. Manufacturing method of magnetic substances. 3. The method for producing a magnetic substance according to claim 2, wherein the iron oxide-based magnetic component is a ferrite compound.