JPS608336A - Composite material having magnetism - Google Patents

Abstract

PURPOSE:To obtain the titled composite material having both soft magnetism and electrical insulation, and excellent formability, by embedding small pieces of iron-based magnetic material having an oxide coating film of specific thickness at a specific ratio in a resin or rubber. CONSTITUTION:Iron powder having a diameter of preferably <=100mu, iron fiber having a diameter of <=100mu, or small pieces of iron composed of flakes of <=100mu thickness 3a, 3b are boiled, e.g. in NaOH, washed with water, and dried in a heating furnace to form an oxide film 4a, 4b having a thickness of 0.5- 50mu to its surface. The small pieces of the magnetic material are added to a resin or rubber 2 in an amount of 30-90wt% to obtain the objective composite material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite material made by adding a magnetic material made of iron to a resin or rubber material to have both soft magnetism and electrical insulation properties.

Composite materials have conventionally been used for various purposes by taking advantage of the good shapeability of resin or rubber materials, but composite materials are made by adding small pieces of soft magnetic material such as iron powder. In composite materials in which iron powder is added to resin or rubber, which gives soft magnetism to products with complex shapes, increasing the amount added causes the iron powder to approach each other, resulting in a decrease in electrical insulation. However, there was a drawback in that composite materials containing a large amount of iron powder could not be used in products that required electrical insulation.

The present invention improves the above-mentioned drawbacks and provides a composite material made of resin or rubber that has both characteristics of soft magnetism and electrical insulation, and has excellent formability.

That is, the present invention is characterized in that iron-based metal strips having an oxide film formed on their surfaces are added to a resin or rubber material. It goes without saying that the oxide film on the surface of iron-based metals has electrical insulation properties, and since iron-based metal strips are mostly made of iron, they exhibit soft magnetism when exposed to an external magnetic field. Therefore, a composite material in which iron-based steel pieces such as iron powder or iron grains having an oxide film are mixed into a resin or rubber material has both electrical insulation properties and soft magnetism.

Resin composite materials to which iron oxide is added as a magnetic material with electrical insulation properties have low magnetic permeability due to the characteristics of iron oxide itself, making them unsuitable as soft magnetic materials. When coating the iron powder to form a composite with resin, it is very difficult to coat the entire surface uniformly because the iron powder tends to aggregate if it is coated on each individual surface of the iron powder. be. On the other hand, the method of securing electrical insulation through an oxide film is that the method of forming an oxide film can be easily formed using a heating furnace, etc., and is also highly reliable. The roughened surface improves mechanical adhesion to resin or rubber materials, and also improves chemical adhesion to hydrophilic resins. Or it is a composite material with excellent adhesion to rubber.

Embodiments of the present invention will be specifically described below with reference to FIGS. 1 and 2.

Example-1 Iron powder of about 60 to 70 μm was boiled in 20% Na011 for 5 minutes, filtered, washed with water, and heated in a furnace at 120°C for 3 minutes.
The iron powder is dried for 0 minutes to form an oxide film on the surface of the iron powder.Then, this iron powder is added to 4M fat such as polybutantaphrate (PBT) in the extruder of Fitman 9, and blended. The ratio of 75% by weight of the iron powder is mixed to form a composite material, and Figure 1 shows a cross section of the composite material t, where 2a, 2b, --- are resin, 3a, 3
b, . . . are iron powders, and 4a, 4b, .

Further, Table 1 shows a comparison of the characteristics when 75% wet iron is mixed into PBT and when 80% iron oxide is mixed only.

From this table, the initial magnetic permeability of Example 1 is approximately 75% PB.
It showed almost the same performance as 2 which mixed T, the volume resistivity was the same as 3 which mixed 80% PBT with iron oxide, and the tensile strength was superior to 2 and 3. As shown in the figure, A shows the Vi1 gas characteristic, and B shows 75% iron PBTSC and 80% iron oxide PBT.

Table 1: Particles with a size of 100 μm or less, fibers with a thickness of 100 μm or less, or fibers with a thickness of 10゛0 μm, with an oxide film of about 0.5 to 50 μm in thickness, in place of the woven iron powder having an oxide film in Table 1 It may be in the form of flakes or a mixture of each.

Examples of the resin include polybutylene tafrate, polyamide, polypropylene, polyoxymethylene, polyethylene, polyester, polyether, acrylonitrile, bucadien, styrene, and the like.

Example 2 Next, in the same manner as Example 1, an oxide film was formed on the surface of 60 to 70 μm iron powder, mixed into nitrile rubber (NBR) at a weight ratio of 90%, and a test piece was created by kneading and extrusion forming. Similarly, NBR4 is 90% ferrite and 90%
A test piece was made by mixing iron powder, and its initial magnetic permeability was measured. The results are shown in Table 2.

Table 2: Specific resistance values other than those containing 90% iron are 10j10''
rL or more. As a result, this example is extremely excellent even in terms of initial magnetic permeability G.

[Brief explanation of drawings]

FIG. 1(a) is an enlarged sectional view of an embodiment of the present invention, and (b) is an enlarged sectional view of an embodiment of the present invention.
is an enlarged sectional view of the conventional example, and the second figure and the first figure (a)
2 is a graph showing the relationship between magnetic flux density and magnetizing force.

Claims (1)

[Claims] (1148 (Referring to 30 to 90% by weight of thin pieces of magnetic material made of iron having an oxide film with a thickness of 0.5 to 50 μm mixed into fat or rubber material) A composite material characterized by: (2) The magnetic material strips include iron powder with a size of 10011 m or less, iron-based fibers with a thickness of 100 μm or less, or iron-based fibers with a thickness of 10 μm or less.
A composite material according to claim 1, characterized in that the composite material is composed of flakes of 0 μm or less.