JPH09326308A - Manufacture of r-fe-b permanent magnet having electric insulation coating with excellent adhesion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide AN R-Fe-B permanent magnet which has a sufficient adhesion only on its local or predetermined area of its surface, on which a polyimide coating having an excellent electrically-insulating property is formed, and which magnet is suitably used for such applications as a relay (electromagnetic switch) to be used for driving an electronic machine or motor requiring a local electrically-isolating property. SOLUTION: A magnet is cleaned on its surface by an ion sputtering process, and then the cleaned surface of the magnet is subjected to such a vapor phase thin-film formation process as a plating process or an ion plating process to form thereon an underlying metallic film made of metal such as Al, Ti, Ni, Zn, Sn or Fe or alloy having a predetermined thickness and a good adhesion to an R-Fe-B permanent magnet. Thereafter, the underlying metallic film is processed with phosphate and then applied with silane coupling agent which has good adhesions to the phosphate film and to polyimide resin. Thereafter polyimide resin is formed on the agent surface by a vapor deposition polymerization process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an R-Fe-B system permanent magnet, and an R-Fe-B system permanent magnet is provided with a base metal layer having a predetermined film thickness on the surface thereof, and further on the base metal film. After the phosphate coating and the silane coupling agent are laminated, the silane coupling coating is coated with polyimide resin by vapor deposition polymerization, which is used to drive electronic devices and motors. The present invention relates to an R-Fe-B based permanent magnet suitable for applications in which electrical insulation with excellent local adhesion is required in a container and the like, and a method for producing the same.

[0002]

2. Description of the Related Art R-Fe-B permanent magnets have the best magnetic properties among the practically used magnets, but they are electrically conductive and have poor corrosion resistance and temperature characteristics of magnetic properties. Because of the drawbacks, the inventors have discovered that a polyimide coating is applied to the surface of the magnet by vapor deposition polymerization to improve the electrical insulation, heat resistance, and corrosion resistance of the magnet.

However, it has been found that when forming a polyimide coating on the surface of a magnet, water is generated during vapor deposition polymerization and imidization treatment to impede the adhesion of the polyimide coating and the corrosion resistance and heat resistance of the magnet. As a result of further study, the inventor first found that the carbon film or the underlying metal film or the underlying metal film was an Al film or a Zn film on the surface of the magnet.
In the case of a film, it was proposed to form a chromate film and then a polyimide film (Japanese Patent Application Nos. 7-43482 and 8-96019).

[0004]

The above method is effective when a polyimide coating is formed on the entire surface of the object to be treated, but depending on the application such as a relay, the polyimide coating may be formed locally or only on the required surface. However, since the adhesion between the magnet and the polyimide coating is not sufficient, there is a problem that peeling may occur locally or from the end of the required surface, and it was not applicable.

Recently, for the purpose of improving the adhesion strength between the corrosion resistant organic coating and the permanent magnet body and improving the corrosion resistance, the chromate coating, the silane coupling agent and the polyparaffin are formed on the surface of the rare earth / iron permanent magnet body. A technique for laminating a film of xylylene has been proposed (Japanese Patent Publication No. 7-9846).
issue).

However, in the technique proposed above, although the adhesion strength between the corrosion-resistant organic coating and the permanent magnet body is certainly improved, polyparaxylylene, which is a corrosion-resistant organic coating, is more electrically insulating than polyimide. And adhesion resistance and corrosion resistance are not good because there is no corrosion resistance and corrosion resistance, and there is no underlying metal film, and there is a very high electrical insulation and good local or desired surface, which is the object of this invention. It was insufficient to be applied to applications such as relays that require corrosion resistance and heat resistance.

An object of the present invention is to provide an R-Fe-B system permanent magnet suitable for applications such as a relay (electromagnetic switch) which is required to have local electrical insulation when driving an electronic device or a motor. The R-Fe-B system permanent magnet surface is provided with a polyimide coating excellent in electrical insulation by providing sufficient adhesion locally or only on the required surface.
It is an object of the present invention to provide an Fe-B based permanent magnet and a method for manufacturing the same.

[0008]

The inventors have found that R-Fe-
On the surface of the B-system permanent magnet body or only on the required surface,
As a result of various studies on a method of forming a polyimide coating film by improving adhesion, a base metal film is formed on the surface of the R—Fe—B based permanent magnet body, and then the metal film is subjected to a phosphate treatment, After that, after applying a silane coupling agent having good adhesion to the phosphate coating, by depositing a polyimide resin on the silane coupling surface, the phosphate coating has a porous and uneven shape. A role to increase the corrosion resistance by filling the holes and recesses of the underlying metal film with a phosphate treatment to improve the corrosion resistance and to promote the reaction between the underlying metal film and the silane coupling agent, which in turn improves the adhesion of the polyimide film. Also contributes to the improvement of corrosion resistance, and improves the adhesion between the phosphate coating and the silane coupling of the underlayer and the silane coupling and the polyimide coating,
The inventors have found that a polyimide resin having excellent electrical insulation, corrosion resistance, and heat resistance, which is excellent locally or on a required surface, can be applied to the surface of the R—Fe—B system permanent magnet, and completed the present invention.

That is, according to the present invention, the main phase has a film thickness of 1.0 μm on the surface of the R—Fe—B system permanent magnet body composed of tetragonal crystals.
After applying a base metal film of m to 10 μm, a phosphate coating, a silane coupling agent, and a polyimide coating of 2.0 μm to 10 μm in thickness on the outermost surface are laminated on the base metal film to provide excellent adhesion. R-Fe-B with insulating coating
R-Fe-B which is a system permanent magnet, and in the above structure, the base metal layer has Al, Ti, Ni, Zn, Su, Fe and alloys thereof with an electrically insulating coating having excellent adhesion. System permanent magnets are also proposed.

Further, according to the present invention, as a method for producing the above-mentioned R-Fe-B system permanent magnet, the main phase is R composed of a tetragonal crystal.
After cleaning the surface of the —Fe—B-based permanent magnet body by an ion sputtering method or the like, the magnet body is formed on the surface of the magnet body by a vapor deposition method such as a plating method, an ion plating method, an ion sputtering method, or a vapor deposition method. After forming a base metal film having a film thickness of 1.0 μm to 10 μm with good adhesiveness, a phosphate treatment and applying a silane coupling agent on the phosphate coating, the magnet body is placed in a vacuum container. And a polyimide film layer having a film thickness of 2.0 μm to 10 μm on the outermost surface by a vapor deposition polymerization method, and a method for producing an R-Fe-B system permanent magnet having an electrically insulating coating having excellent adhesion. suggest.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the thickness of the base metal film provided on the cleaned magnet surface is 1.0 μm to 10 μm.
The reason for limiting the thickness to 0 μm is that if it is less than 1.0 μm, a sufficiently high corrosion resistance cannot be obtained, and if it exceeds 10.0 μm, there is no problem in terms of effectiveness, but the cost increases as a base film,
Since it is not practical and not preferable, the thickness of the underlying metal film is 1.0
μm to 10.0 μm. Preferred metal film thickness is 6 μm
~ 8 μm.

Further, the method of forming the underlayer metal film may be a plating method such as an electrolytic plating method or an electroless plating method, or a vapor phase thin film forming method such as an ion plating method, an ion sputtering method, or vapor deposition. In the present invention, the underlying metal film is made of Al having good adhesion to the R-Fe-B system permanent magnet,
Ti, Ni, Zn, Sn, Fe and alloys thereof are preferred.

In the present invention, the phosphate coating is R-
A treatment solution containing zinc phosphate, manganese phosphate, zinc calcium phosphate, iron phosphate, tin phosphate, etc., which is generally used as a base treatment for coating, etc., by treating the Fe-B permanent magnet body with a phosphate. It is obtained by dipping in or spraying. The film thickness of the coating film is 10 nm to 100 nm.

In the present invention, in the silane coupling treatment, the permanent magnet body having a phosphate coating on the underlying metal film is dipped in a silane coupling agent or a solution thereof and then dried in the air. Silane coupling agent film thickness is 5 nm
２００200 nm. The silane coupling agent is
A silane coupling agent having a vinyl group or a γ group can be selected, which undergoes a condensation reaction and firmly adheres with an oxide coating such as a phosphate coating, but is preferably represented by the following chemical formula. Γ-glycidpropyltrimethoxysilane shown is preferable.

[0015]

Embedded image

The reason why the thickness of the polyimide resin is limited to 2.0 μm to 10 μm in the present invention is that if the thickness is less than 2.0 μm, the coating is not sufficient and a coating excellent in corrosion resistance cannot be obtained, and if it exceeds 10 μm, it is effective. There is no problem, but it is not practical and is not preferable because it causes an increase in manufacturing cost.

Further, in the present invention, in the vapor deposition polymerization method, two kinds of monomers, which are raw materials for the polyimide film, are put in a vacuum container having a vacuum degree of 1 Pa to 10 ^-3 Pa at 200 ° C to 250 ° C.
After vapor deposition by heating to form a polyamic acid film, under normal pressure,
It is preferable to perform imidization at 280 ° C. to 380 ° C. to form a polyimide film.

In the present invention, the reason why the vacuum degree of the vacuum vessel for vapor deposition polymerization is limited to 1 Pa to 10 ^-3 Pa is 1 P.
If it exceeds a, the polymerization reaction becomes non-uniform and the film quality deteriorates. If it is less than 10 ^-3 Pa, the evaporation of the monomer is extremely small and a stable polymerization reaction does not occur, which is not preferable. Furthermore, the temperature of the substrate magnet during vapor deposition polymerization is 15
The temperature is preferably set to 0 ° C. to 200 ° C. When the temperature is lower than 150 ° C., the adhesion to the magnet substrate is insufficient, and when the temperature is higher than 200 ° C., the vapor deposition polymerization reaction on the magnet substrate does not proceed promptly, so that the temperature of the substrate magnet is reduced. Is preferably set to 150 to 200 ° C.

In the present invention, the two kinds of raw material monomers used for vapor deposition polymerization are aromatic carboxylic acid dianhydrides and aromatic diamines, and aromatic carboxylic acid dianhydrides include pyromellitic dianhydride and the like. As the aromatic diamine, diaminodiphenyl ether, p-phenyldiamine and the like are used. The reason for accelerating vapor deposition of two kinds of raw material monomers at 200 ° C. to 250 ° C. in a vacuum container is 2
This is because if the temperature is less than 00 ° C, the amount of evaporation is not sufficient, and if it exceeds 250 ° C, the evaporation rate is too high to control the film thickness, which is not preferable.

Further, in the present invention, if the imidization temperature for producing the polyimide resin is less than 280 ° C., the imidization reaction does not proceed sufficiently, the adhesion with the silane coupling agent is insufficient, and the imidization temperature exceeds 380 ° C. And the polyimide resin deteriorates and becomes brittle, causing cracks and peeling. 2
It is set to 80 ° C to 380 ° C.

The rare earth element R used in the permanent magnet of the present invention
Accounts for 10 to 30 atomic% of the composition, but Nd,
At least one of Pr, Dy, Ho, and Tb; or La, Ce, Sm, Gd, Er, Eu, T
Those containing at least one of m, Yb, Lu, and Y are preferable. Also, usually one of R is sufficient,
In practice, a mixture of two or more kinds (mish metal, dymium, etc.) can be used for reasons such as convenience in obtaining. It should be noted that this R does not have to be a pure rare earth element, and may contain an impurity that is unavoidable in manufacturing within the industrially available range.

R is an essential element in the R-Fe-B system permanent magnet, and if it is less than 10 atomic%, the crystal structure is a cubic structure having the same structure as α-iron, so that high magnetic properties, especially high coercive force are obtained. If it exceeds 30 atomic%, the R-rich non-magnetic phase increases, the residual magnetic flux density (Br) decreases, and a permanent magnet having excellent characteristics cannot be obtained. Therefore, R is 1
A range of 0 to 30 atomic% is desirable.

B is an essential element in the above-mentioned permanent magnet. When it is less than 2 atomic%, a rhombohedral structure is the main phase and a high coercive force (iHc) cannot be obtained.
Since a rich non-magnetic phase increases and the residual magnetic flux density (Br) decreases, an excellent permanent magnet cannot be obtained. Therefore, B is desirably in the range of 2 to 28 atomic%.

Fe is an essential element in the above-mentioned permanent magnets. If it is less than 65 atom%, the residual magnetic flux density (Br) is lowered, and if it exceeds 80 atom%, a high coercive force cannot be obtained. % To 80 atomic% is desirable.
Further, substituting part of Fe with Co can improve the temperature characteristics without impairing the magnetic characteristics of the obtained magnet. However, when the amount of Co exceeds 20% of Fe, the conversely occurs. It is not preferable because the magnetic properties deteriorate. When the amount of substitution of Co is 5 at% to 15 at% in terms of the total amount of Fe and Co, (Br) is increased as compared with the case where no substitution is made, which is preferable for obtaining a high magnetic flux density.

In addition to R, B, and Fe, the presence of unavoidable impurities in industrial production can be tolerated. For example, part of B may be 4.0 wt% or less of C, 2.0 wt% or less of P, .0
By replacing at least one of S by wt% or less and Cu by 2.0 wt% or less with a total amount of 2.0 wt% or less, it is possible to improve the productivity and reduce the cost of the permanent magnet.
Furthermore, Al, Ti, V, Cr, Mn, Bi, Nb, T
a, Mo, W, Sb, Ge, Sn, Zr, Ni, Si,
At least one of Zn and Hf is added to the R—Fe—B system permanent magnet because it is effective in improving the coercive force, squareness of demagnetization curve, improving manufacturability, and reducing cost. can do. The upper limit of the addition amount is (BH) max of 20 MGOe or more for the magnet material,
Since r) is required to be at least 9 kG or more, a range satisfying the condition is desirable.

The permanent magnet of the present invention comprises a compound having a tetragonal crystal structure having an average crystal grain size in the range of 1 to 80 μm as a main phase, and a nonmagnetic phase (1% to 50% by volume). (Excluding the oxide phase). The permanent magnet according to the present invention exhibits a coercive force iHc ≧ 1 kOe, a residual magnetic flux density Br> 4 kG, and a maximum energy product (BH).
max indicates (BH) max ≧ 10 MGOe, and the maximum value reaches 25 MGOe or more.

[0027]

EXAMPLE A cast ingot having a composition of 17Nd-1Dy-76Fe-6B was crushed, finely crushed, molded, sintered, and heat-treated to obtain a disk-shaped magnet body test piece having a diameter of 20 mm × 7 mm. Table 1 shows the magnetic properties. 1x1 in the vacuum container
Evacuated to 0 ^-3 Pa or less, Ar gas pressure 10 Pa, -5
After the surface of the magnet body was cleaned by performing surface sputtering at 00 V for 15 minutes, Ti, Al, Zn, and S shown in Table 2 were formed on the surface of the magnet body under the ion plating conditions shown in Table 2.
A base metal coating layer of n and Fe was formed. The Ni undercoat layer was formed by an electroplating method.

Next, it was immersed in a 10% solution of Surfdyne SD-2000 (manufactured by Nippon Paint Co., Ltd.) at 40 ° C. for 5 minutes, and 1
Air-dry at 00 ° C. to obtain a zinc phosphate coating with a film thickness of 20 nm, then dip treatment with γ-glycidpropyltrimethoxysilane for 3 minutes, and dry at 150 ° C. for 30 minutes,
A silane coupling film having a film thickness of 10 nm was obtained.

After that, the obtained permanent magnet was housed in a vacuum container, and the inside of the vacuum container was set to a vacuum degree of 1 × 10 ^-2 Pa.
Pyromellitic dianhydride at 220 ° C as one evaporation source
And diaminodiphenyl ether as another evaporation source at 210 ° C. and the magnet substrate at 170 ° C. for 1.5 hours for the raw material monomer to be vaporized on the surface of the magnet. Then, a polyamic acid film was formed.

Next, under normal pressure, it was heated in a nitrogen atmosphere at 300 ° C. for 1 hour for imidization treatment to form a polyimide resin film, thereby forming a polyimide resin film with a thickness of 8 μm. The permanent magnet body having the polyimide resin film on the surface thus obtained was used as a test piece for measuring magnetic properties and volume resistivity before and after the corrosion resistance test. Here, the volume resistivity is for evaluating electrical insulation and is obtained from the following formula (1).

[0031]

[Equation 1]

Further, a permanent magnet having a polyimide resin film on the surface was cut into test pieces each having a rectangular parallelepiped shape with dimensions of 10 mm × 10 mm × 7 mm and having polyimide resin on the upper and lower surfaces. After the piece was left for 1000 hours under the conditions of a temperature of 80 ° C. and a relative humidity of 90%, the surface rusting state and magnetic characteristics of the polyimide film forming surface were measured, and the measurement results are shown in Table 3.

Comparative Example 1 A magnet body test piece having the same composition as in Example 1 was subjected to phosphate treatment and silane coupling under the same conditions as in Example 1, and then the surface was subjected to polyimide under the same conditions as in Example 1. The resin film was formed to a thickness of 8 μm. Then, at the same temperature as in Example 1, 8
After leaving for 1000 hours at 0 ° C and 90% relative humidity,
The surface rusting condition and magnetic property of the polyimide film formation surface were measured, and the results are shown in Table 3.

Comparative Example 2 A magnet body test piece having the same composition as in Example 1 was formed with a Ti undercoat metal coating layer of 6.0 μm under the same conditions as in Example 1, and the silane cup was subjected to the same conditions as in Example 1. After applying the ring agent, a polyimide resin film having a thickness of 8 μm was formed on the surface. After that, after standing for 1000 hours under the same temperature of 80 ° C. and relative humidity of 90% as in Example 1, the surface rusting state and magnetic characteristics of the polyimide film forming surface were measured, and the results are shown in Table 3.

Comparative Example 3 A magnet test piece having the same composition as that of Example 1 was formed with a Ti undercoat metal coating layer of 6.0 μm under the same conditions as in Example 1, and phosphoric acid was obtained under the same conditions as in Example 1. After the zinc treatment, a polyimide resin film having a thickness of 8 μm was formed on the surface. Thereafter, under the same conditions as in Example 1 at a temperature of 80 ° C. and a relative humidity of 90%, 1
The surface rusting condition and the magnetic property of the polyimide film formation surface after standing for 000 hours were measured, and the results are shown in Table 3.

Comparative Example 4 A magnet body test piece having the same composition as in Example 1 was replaced with Alsurf 600.
After dipping in a 3% solution of N (manufactured by Nippon Paint) at 50 ° C. for 5 minutes and subjecting it to zinc phosphate treatment, a silane coupling agent was applied under the same conditions as in Example 1, and polyparaxylylene was applied to the surface. Was vacuum-deposited to a thickness of 8 μm. afterwards,
The volume resistivity before and after standing for 1000 hours under the same temperature of 80 ° C. and relative humidity of 90% as in Example 1 was measured, and the results are shown in Table 4.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

According to the present invention, after the magnet surface is cleaned by an ion sputtering method or the like, an R-Fe-B system permanent is formed on the magnet surface by a vapor phase thin film forming method such as a plating method or an ion plating method. After forming a base metal film of a metal or alloy coating such as Al, Ti, Ni, Zn, Sn, and Fe having a specific film thickness with good adhesion to a magnet, a phosphate treatment is performed on the base metal film. After applying a silane coupling agent having good adhesiveness with an acid salt film and an adhesiveness with a polyimide resin, by forming a polyimide resin on the outermost surface by a vapor deposition polymerization method, as shown in Examples, the purpose and A highly efficient R-Fe-B permanent magnet that can be used for a relay, which is required to have local electrical insulation, is obtained.

Claims (3)

[Claims] 1. A base metal film having a thickness of 1.0 μm to 10 μm is formed on the surface of an R—Fe—B based permanent magnet body whose main phase is tetragonal, and then a phosphate coating is formed on the base metal film. Silane coupling agent and film thickness of 2.0 μm to 10 μm on the outermost surface
An R-Fe-B based permanent magnet having an electrically insulating coating having excellent adhesion, which is obtained by laminating the polyimide coating of 1. 2. The base metal layer according to claim 1, wherein the base metal layer is A
An R-Fe-B based permanent magnet having an electrically insulating coating having excellent adhesion, which is characterized in that it is 1, Ti, Ni, Zn, Sn, Fe, or an alloy thereof. 3. A film having a thickness of 1.0 .mu.m-10.0 .mu.m formed on the surface of the magnet body by a plating method or a vapor deposition method after cleaning the surface of the R--Fe--B system permanent magnet body whose main phase is tetragonal.
After forming a base metal film of m, the metal film is subjected to a phosphate treatment, a silane coupling agent is laminated on the phosphate film, and then the magnet body is further housed in a vacuum container to perform a vapor deposition polymerization method. A method for producing an R-Fe-B permanent magnet having an electrically insulating coating having excellent adhesion, which forms a polyimide film layer having a thickness of 2.0 μm to 10 μm.