JPH09232133A - Flexible permanent magnet sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flexible permanent magnet sheet which is applicable to health appliances, stationery, toys and the like utilizing magnetic power, and a method for manufacturing the sheet. SOLUTION: The permanent magnet sheet comprises a flexible polyurethane resin sheet containing diffused permanent magnet powder which is needle-type iron powder covered with cobalt, neodymium oxide, neodymium and baron, or diffused permanent magnet powder which is needle-type iron powder covered with cobalt, nickel, neodymium oxide, neodymium and boron. The permanent magnet material powder which is the needle-type iron powder covered with cobalt, neodymium oxide, neodymium and baron, or the permanent magnet material powder which is the needle-type iron powder covered with cobalt, nickel, neodymium oxide, neodymium and boron is mixed with polyisocyanate and polyol, and a foaming agent and catalyst is added to the mixture so as to cause reaction between the polyisocianate and polyol, thus the mixture is formed into a sheet. Then the sheet is magnetized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible permanent magnet sheet suitable for application to health equipment, stationery, toys, etc. that utilize magnetic force.

[0002]

2. Description of the Related Art As a flexible permanent magnet sheet, there is a rubber magnet in which a powder of permanent magnet raw material and rubber are mixed and molded into a sheet and magnetized. However, it can be stuck along a curved surface or an uneven surface. Since it is not flexible and the mixing limit of the permanent magnet raw material powder is small, sufficient magnetic force cannot be obtained. On the other hand, a plastic magnet obtained by molding and magnetizing a permanent magnet raw material powder using a nylon resin, an epoxy resin or the like as a binder lacks flexibility. Magnetic health implements such as electric vans and magnetic pillows use hard pellet-shaped permanent magnets, which have a hard feel and cannot provide a uniform magnetic force as a surface.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible permanent magnet sheet and a method for manufacturing the same.

[0004]

The flexible permanent magnet sheet according to the present invention is a permanent magnet powder in which metallic cobalt, neodymium oxide, metallic neodymium and boron are present on the surface of acicular iron powder, or acicular iron. The permanent magnet powder having metallic cobalt, metallic nickel, neodymium oxide, metallic neodymium and boron present on the surface of the powder is dispersed in a flexible polyurethane resin sheet. Such a flexible permanent magnet sheet is a permanent magnet raw material powder in which metallic cobalt, neodymium oxide, metallic neodymium and boron are present on the surface of acicular iron powder, or metallic cobalt, metallic nickel on the surface of acicular iron powder. , Mixing neodymium oxide, neodymium metal oxide, and permanent magnet raw material powder containing boron with polyisocyanate and polyol, adding a foaming agent and a catalyst to react polyisocyanate and polyol, and forming into a sheet and then magnetizing Manufactured by.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A flexible polyurethane resin sheet is formed by mixing a polyisocyanate and a polyol, adding a foaming agent and a catalyst to react the polyisocyanate and the polyol, and extruding into a sheet shape. As the polyisocyanate, tolylene diisocyanate (TD
Any of aromatic polyisocyanates such as I) and aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI) can be used. As the polyol, a polyether polyol such as polypropylene glycol is preferably used, but a polyester polyol can also be used depending on the purpose of use. As a catalyst, an organometallic compound such as dibutyltin dilaurate, or a tertiary amine such as triethylenediamine,
Water or fluorocarbons is used as the foaming agent. A polyurethane resin sheet having an arbitrary density and an arbitrary flexibility can be produced by selecting the raw materials, the use ratio, the foaming conditions and the like. This is a technique well known to those skilled in the art.

In the present invention, when polyisocyanate and a polyol are mixed and a polyisocyanate and a polyol are reacted by adding a foaming agent and a catalyst, at least one of metallic cobalt and metallic nickel is formed on the surface of the acicular iron powder. The seed, neodymium oxide, neodymium metal, and permanent magnet raw material powder in the presence of boron are mixed. As the permanent magnet raw material powder, ferrite type, Al-Ni-Co type, Fe-
Various types such as B-Nd type are known, but the conventional permanent magnet raw material powder is not well compatible with the polyurethane raw material mixture, and a homogeneous mixed composition cannot be obtained. As a result, the raw material powder of permanent magnets is non-uniformly dispersed in the obtained polyurethane resin sheet, which not only makes the distribution of magnetic force non-uniform but also lowers the tear strength. On the other hand, the permanent magnet raw material powder in which metallic cobalt, neodymium oxide, metallic neodymium and boron are present on the surface of the acicular iron powder, or metallic cobalt, metallic nickel, neodymium oxide, metallic neodymium on the surface of the acicular iron powder. The raw material powder of permanent magnet containing boron and boron is well compatible with the raw material mixture of polyurethane, and a homogeneous mixed composition can be obtained. As a result, the permanent magnet powder is uniformly dispersed in the obtained polyurethane resin sheet,
Not only the distribution of magnetic force becomes uniform, but also the tear strength can be maintained. From another viewpoint, more permanent magnet raw material powders can be mixed with the same tear strength, and a stronger permanent magnet sheet can be obtained. The mixing ratio of the permanent magnet raw material powder and the polyurethane raw material mixture is 20 to 90% by weight, preferably 30 to 90% by weight of the permanent magnet raw material powder in the permanent magnet sheet.
It is better to set it to 00% by weight.

The permanent magnet raw material powder used in the present invention is one in which metallic cobalt, neodymium oxide, metallic neodymium and boron are present on the surface of acicular iron powder, or metallic cobalt, metallic nickel on the surface of acicular iron powder, Neodymium oxide, neodymium metal and boron are present. Metallic cobalt is 1 to 15% by weight of acicular iron powder, metallic nickel is 0 to 5% by weight of acicular iron powder, neodymium oxide is 1 to 20% by weight of acicular iron powder, and metallic neodymium is acicular. 1-2 for iron powder
It is preferable that 0 wt% and boron are present in an amount of 0.1 to 2 wt% with respect to the acicular iron powder.

The acicular iron powder preferably has a length of 10 μm or less and a width of about 1/10 of the width obtained by heating FeOOH (goethite) to 300 to 500 ° C. in a hydrogen atmosphere and reducing it with hydrogen. Further, it is preferable that the average particle size of the metal neodymium powder is on the order of microns (μm) and the average particle size of the boron powder is on the order of microns.

The permanent magnet raw material powder of the present invention is FeOOH.
(Goethite) A water-soluble cobalt salt or a water-soluble cobalt salt and a water-soluble nickel salt, and a water-soluble neodymium salt are added to needle-shaped crystals to adhere to the surface of the FeOOH needle-shaped crystals, and after neutralization with alkali and washing with water, air or It can be obtained by firing treatment in an oxygen-enriched gas, further adding and mixing metal neodymium powder and boron powder, and performing reduction treatment in a hydrogen-containing gas. When it is necessary to adjust the particle size, pulverize after reduction treatment. It is preferable to use cobalt nitrate as the water-soluble cobalt salt, nickel nitrate as the water-soluble nickel salt, and neodymium nitrate as the water-soluble neodymium salt. Baking treatment is 400-450 ° C for 3-4 hours, and reduction treatment is 300-
It is preferable to carry out at 500 ° C. for 5 to 6 hours. Upon neutralization with alkali, the water-soluble cobalt salt becomes cobalt hydroxide, the water-soluble nickel salt becomes nickel hydroxide, and the water-soluble neodymium salt becomes neodymium hydroxide, which adheres to the FeOOH needle crystals. By the subsequent firing treatment, FeOOH needle crystals become needle iron oxide (hematite), cobalt hydroxide becomes cobalt oxide, nickel hydroxide becomes nickel oxide, and neodymium hydroxide becomes neodymium oxide. When metal neodymium powder and boron powder are added and mixed to this and subjected to reduction treatment in a hydrogen-containing gas, needle-shaped iron oxide becomes needle-shaped iron powder, cobalt oxide becomes metal cobalt nickel oxide becomes metal nickel, but oxidation occurs. Neodymium remains.

Since the permanent magnet raw material powder produced by the above method is easily oxidized by oxygen in the air, after the reduction treatment, it is contacted with nitrogen gas containing a trace amount, for example, 0.5% oxygen, at room temperature for several hours. It is desirable to perform a stabilizing treatment for forming an oxide film on the surfaces of the acicular iron powder, metallic cobalt, metallic nickel and metallic neodymium.

The shape may be an arbitrary shape such as a flat sheet or a cylinder depending on the purpose of use.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0013]

Examples 1 and 2 Polyether polyol mixture 100
1. A mixture of 1 part by weight and a reaction equivalent of tolylene diisocyanate (36 parts by weight) was mixed with 140 parts by weight of a permanent magnet raw material powder having the composition shown in Table 1, 1.2 parts by weight of an amine catalyst and water as a foaming agent. Add 5 parts by weight to react, thickness
After being formed into a mm-shaped sheet, it was magnetized. In both the sheet of Example 1 and the sheet of Example 2, the permanent magnet powder was uniformly dispersed in the polyurethane resin, and the sheet was flexible.

[0014]

[Table 1]

[0015]

INDUSTRIAL APPLICABILITY The flexible permanent magnet sheet obtained by the present invention is so flexible that it can be attached to a curved surface or an uneven surface, and when used in a magnetic health tool such as an electric van or a magnetic pillow to be attached to a local part of the human body There is no feeling of foreign matter and it can be used comfortably.
It can be expected to be applied to pillow covers and supporters.

Claims (7)

[Claims] 1. A permanent magnet powder in which metallic cobalt, neodymium oxide, metallic neodymium and boron are present on the surface of acicular iron powder, or metallic cobalt, metallic nickel, neodymium oxide, metallic neodymium on the surface of acicular iron powder. And a permanent magnet powder containing boron dispersed in a flexible polyurethane resin sheet. 2. The needle-shaped iron powder is FeOOH (goethite).
The flexible permanent magnet sheet according to claim 1, which is obtained by heating and reducing needle crystals in a hydrogen-containing gas. 3. The flexible permanent magnet sheet according to claim 1, wherein the sheet is formed into a flat plate shape. 4. The flexible permanent magnet sheet according to claim 1, wherein the sheet is formed into a tubular shape. 5. A raw material powder for a permanent magnet having metallic cobalt, neodymium oxide, metallic neodymium and boron present on the surface of acicular iron powder, or metallic cobalt, metallic nickel, neodymium oxide, metallic on the surface of acicular iron powder. Softness characterized by mixing polyisocyanate and polyol with a permanent magnet raw material powder in which neodymium and boron are present, reacting polyisocyanate and polyol by adding a foaming agent and a catalyst, magnetizing after being formed into a sheet shape Method for producing a permanent magnet sheet. 6. The method for producing a flexible permanent magnet sheet according to claim 5, wherein a needle-like iron powder obtained by heating and reducing FeOOH (goethite) needle crystals in a hydrogen-containing gas is used. . 7. A permanent magnet raw material powder, wherein a water-soluble cobalt salt or a water-soluble cobalt salt and a water-soluble nickel salt, and a water-soluble neodymium salt are added to FeOOH (goethite) needle-shaped crystals to form a surface of the FeOOH needle-shaped crystals. The method according to claim 5, which is obtained by adhering, baking treatment in air or oxygen-enriched gas, further adding and mixing metal neodymium powder and boron powder, and reducing treatment in hydrogen-containing gas. A method for manufacturing a flexible permanent magnet sheet.