JP2002060674A - Resin composition for coating rare earth permanent magnet and rare earth permanent magnet having coating film of the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for a rare earth permanent magnet which, while overcoming the difficulties in conventional techniques, can be used for forming a surface coating film excellent both in corrosion resistance and in electrical insulating properties and heat resistance by a simple method, and also provide a rare earth permanent magnet having a coating film formed therefrom. SOLUTION: This resin composition essentially contains (A) a bisalkenyl- substituted nadiimide represented by formula [1] and (B) at least one resin selected from among epoxy resins, polysulfone resins, and phenylene sulfide resins. The surface of the rear earth permanent magnet of the invention is coated with the resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating resin composition which can be suitably used for painting or coating which requires corrosion resistance, electrical insulation and heat resistance to rare earth permanent magnets, and a resin composition coated with the resin composition. Rare earth permanent magnets, more specifically, a coating with excellent corrosion resistance, electrical insulation, and heat resistance is applied to the surface of rare earth permanent magnets, which are mainly used in electronic devices including motors for automobiles and home appliances. The present invention relates to a rare earth-based permanent magnet coating resin composition which can be suitably used for forming and a rare earth-based permanent magnet having the resin composition coating on the surface.

[0002]

2. Description of the Related Art Rare earth permanent magnets represented by Nd-Fe-B permanent magnets have high magnetic properties, and are used in various fields including electronic devices including motors for automobiles and home appliances. Used in With the recent reduction in size and weight of motors and electronic devices for automobiles, devices with higher performance are also demanded for magnetic circuits and the like to be used. However, rare-earth permanent magnets are easily oxidized and corroded in the atmosphere, and rust is generated on the surface, resulting in deterioration and variations in magnetic properties.Therefore, the magnet surface is coated with a coating with excellent corrosion resistance. There is a need to.

[0003] Further, it is difficult to secure the clearance between the magnet and the wiring when it is incorporated in a fine circuit, and when it is used for an automobile motor, the temperature in the engine room where the motor is installed is 200 ° C during running. For the reasons mentioned above, the surface coating of the permanent magnet used in such applications is required to have both excellent corrosion resistance and excellent electrical insulation and heat resistance.

In view of the above, for the purpose of imparting excellent corrosion resistance, electrical insulation and heat resistance to a rare-earth permanent magnet, a two-layer coating consisting of a base metal coating and a polyimide resin coating is formed on the magnet surface. (For example, JP-A-60-63902 and JP-A-8-279).
407).

The above prior arts are valuable in forming a corrosion-resistant insulating film having excellent performance on rare-earth permanent magnets, but all of them are formed by plating or vapor deposition. Forming a metal coating;
Using aromatic diamine and aromatic carboxylic dianhydride,
A step of forming a condensation type polyimide resin film by vapor deposition polymerization. Therefore, when the above-described conventional technology is implemented, strict pretreatment such as cleaning or a large-scale apparatus is required for each process, and therefore, the production cost is increased, and it is not always satisfactory from the viewpoint of mass production. Not something to do.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the conventional formation of a corrosion-resistant insulating film, and to provide excellent electrical insulation and heat resistance as well as corrosion resistance by a simple method. It is an object of the present invention to provide a rare earth permanent magnet coating resin composition which can be used for forming a combined surface coating and a rare earth permanent magnet having the resin composition coating.

[0007]

That is, the present inventors have made intensive studies to achieve the above object of the present invention, and as a result, have found that an alkenyl-substituted nadimide is used as a base and at least an epoxy resin, a polysulfone resin or a polyphenylene sulfide resin. The inventors of the present invention have found that a composition containing one type of compound has excellent corrosion resistance due to curing and a film having both excellent electrical insulation properties and heat resistance.

That is, the gist of the present invention is that (A) the general formula [1]

Embedded image[Wherein, R¹, R^TwoIs independently selected hydrogen or
Methyl group, R^ThreeIs C_Two~ C ₂₀Alkylene group, C_Five~ C₈of
Cycloalkylene group, C₆~ C₁₂A divalent aromatic group of-
Aa-C₆H_Four-A'- (a is 0 or 1, A and A 'are
C independently selected₁~ C_FourRepresented by an alkylene group)
Alkylenephenylene group, -C₆H_Four-TC₆H_Four−
(T represents a methylene group, an ethylidene group or a propylidene group.
A) a bisalkenyl group represented by
Exchanged nadimide, (B) epoxy resin, polysulfone tree
Fat or polyphenylene sulfide resin at least
Characterized by containing one kind as an essential component.
Resin composition for coating an earth permanent magnet, and the resin composition
Exists in rare-earth permanent magnets whose surface is covered with an object
You.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the resin composition for coating a rare earth permanent magnet and the rare earth permanent magnet of the present invention will be described in more detail.

As the bisalkenyl-substituted nadimide of the component (A) used in the resin composition for coating a rare earth permanent magnet of the present invention, JP-A-59-80662, JP-A-60-178882, and Known alkenyl-substituted nadimides described in, for example, JP-A-61-18761 and JP-A-63-170358, and Patent No. 272
Various alkenyl-substituted nadimides according to No. 9565 can be used, and specifically, general formula [1]

Embedded image[Wherein, R¹, R^TwoIs independently selected hydrogen or
Methyl group, R^ThreeIs C_Two~ C ₂₀Alkylene group, C_Five~ C₈of
Cycloalkylene group, C₆~ C₁₂A divalent aromatic group of-
Aa-C₆H_Four-A '-(a is an integer of 0 or 1, A,
A 'is independently selected C₁~ C_FourAlkylene
Alkylenephenylene group represented by the formula: ₆H_Four-T
-C₆H_Four-(T is a methylene group, an ethylidene group, a propyl group
A bis group represented by the following formula:
It is a alkenyl-substituted nadimide.

Examples of the bisalkenyl-substituted nadimide represented by the general formula [1] include, for example, N, N'-ethylene-bis (allylbicyclo [2.2.1] hept-5 in which R ³ is an alkylene group. - ene-2,3-dicarboximide), N, N'-hexamethylene - bis (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboximide), C ₅ -C N, N′-cyclohexylene-bis (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboximide) which is a cycloalkylene group of ₈ , and N, N which is an aromatic group '-M-phenylene-bis (allylbicyclo [2.2.1] hept-5-
_{Ene-2,3-dicarboximide), - Aa-C 6 H} 4
-A '- (a is an integer of 0 or 1, A, A' each represent an alkylene group of C ₁ -C ₄ selected independently) an alkylene phenylene group represented by N, N'-p-xylylene -Bis (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboximide), N, N'-m-xylylene-bis (allylbicyclo [2.2.1] hept-5 - ene-2,3-dicarboximide), - C ₆ H _{4
-T-C 6 H 4 - (} T represents a methylene group, ethylidene group, propylidene a group) bis {4- (allylbicyclo a group represented by [2.2.1] hept-5-ene -2, 3
-Dicarboximido) phenyl @ methane and the like.

Among the above-mentioned bisalkenyl-substituted nadimides, in particular, N, N'-hexamethylene-bis (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboximide), N, N ' -M-xylylene-bis (allylbicyclo [2.2.1] hept-5-ene-2,3
-Dicarboximide) and bis {4- (allylbicyclo [2.2.1] hept-5-ene-2,3-dicarboximide) phenyl} methane are preferred.

Further, the compounds exemplified herein in which the allyl group is replaced by a methallyl group, or the compounds exemplified above and the methallyl-substituted compounds thereof, wherein one hydrogen atom of the norbornene ring is replaced by a methyl group Are also exemplified as compounds that can be used in the present invention.

These bisalkenyl-substituted nadimides may be used alone or as a mixture of two or more. These bisalkenyl-substituted nadimides may be used as oligomers. That is, in the present specification, "bisalkenyl-substituted nadimide" is used as a concept including its oligomer.

Further, the epoxy resin, polysulfone resin and polyphenylene sulfide resin of the component (B) used in the resin composition for coating a rare earth permanent magnet of the present invention are blended for improving the coatability of the permanent magnet. Various known ones can be used.

For example, as the epoxy resin, a bisphenol type epoxy resin obtained by a reaction between bisphenol and epichlorohydrin; a novolak type epoxy resin obtained by a reaction between a phenol novolak resin or a cresol novolak resin and epichlorohydrin;
A polyhydroxybenzene type epoxy resin obtained by reacting a polyhydric phenol such as resorcinol or hydroquinone with epichlorohydrin; a nitrogen-containing epoxy resin obtained by reacting an aromatic amine such as toluidine or aniline with epichlorohydrin; cyclohexene, vinylcyclohexene, Cyclopentadiene,
Alicyclic epoxy resin starting from dicyclopentadiene or the like; epoxy resin having a fluorene skeleton; di- or polyglycidyl ethers such as butanediol, hexanediol, glycerin, trimethylolpropane, or pentaerythritol; Silicon-containing epoxy resins obtained by the reaction; epoxy resins having a nitrogen-containing heterocycle obtained from isocyanuric acid or cyanamide; and the like.

Examples of the polysulfone resin include, but are not limited to, polysulfone resins, polyarylsulfone resins, and polyethersulfone resins. Each of these resins of component (B) may be used alone or in combination of two or more.

When the resin composition for coating a rare earth permanent magnet of the present invention, which contains the above components (A) and (B), is cured, the bisalkenyl-substituted nadimide of the component (A) and the component (B) are cured. ) Resin interpenetrates each other to form an entanglement of molecules.
Penetration Network System
m: IPN), and as a result, the corrosion resistance, electric insulation and heat resistance of the coating are improved.

In the rare earth-based permanent magnet coating resin composition of the present invention, the content of the bisalkenyl-substituted nadimide of the component (A) is determined by the desired content of the coating obtained by curing the rare earth-based permanent magnet coating resin composition. In general, the content of the bisalkenyl-substituted nadimide of the component (A) can be selected based on the total weight of the bisalkenyl-substituted nadimide of the component (A) and the resin of the component (B). It is suitable to be 10 to 95% by weight.

If the proportion of the bisalkenyl-substituted nadimide as the component (A) exceeds 95% by weight, the coatability of the resulting resin composition coating on the surface of the permanent magnet is reduced, resulting in reduced corrosion resistance and electrical insulation. Is not preferred,
When the content of the bisalkenyl-substituted nadimide as the component (A) is less than 10% by weight, a sufficient interpenetrating network IPN is not formed, and the effect of improving corrosion resistance, electric insulation and heat resistance is not recognized.

In the resin composition for coating a rare earth permanent magnet of the present invention, in addition to the resin of the component (A) bisalkenyl-substituted nadimide and the resin of the component (B), which are the essential components, the component (C) color pigments such as carbon black and metal oxides and barium sulfate;
Pigments such as extenders such as talc and mica powder can be appropriately blended. The proportion of the component (C) composed of these pigments is suitably not more than 50% by weight based on the total weight of the essential components (A) and (B). However, if it exceeds 50% by weight, the corrosion resistance and adhesion of the coating film decrease. Further, if necessary, a dispersant, an antisettling agent, a plasticizer, a leveling agent, and other additives generally used for a paint or a coating material can be appropriately compounded as the component (C).

When an epoxy resin is used as the component (B) in the present invention, the tertiary amine-based curing catalyst is used as the component (D).
May be added. As the tertiary amine of the component (D), for example, a heterocyclic tertiary amine, an aliphatic tertiary amine and an aromatic tertiary amine can be used. As the heterocyclic tertiary amine, for example, imidazole Pyridine, dimethylaminopyridine, piperidine, piperazine and their alkyl, alkenyl, phenyl, benzyl or N-acyl substituents.

Specific examples of the above imidazole substituent include 1-methylimidazole, 2-ethyl-4-methylimidazole, 2-vinylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1- (3-aminoimidazole) Propyl) -imidazole, 1-
(2,4,6-trimethylbenzoyl) -2-phenylimidazole, 1- (2,6-dichlorobenzoyl)-
2-methylimidazole, 1- (2,6-dichlorobenzoyl) -phenylimidazole, 1- (2,6-dichlorobenzoyl) -2-ethyl-4-methylimidazole, 1- (2,6-dichlorobenzoyl) -4- Phenylimidazole, 1- (2-chloro-6-nitrobenzoyl) -2-ethylimidazole, 1-pentachlorobenzoyl-2-methylimidazole, 1-pentachlorobenzoyl-2-phenylimidazole, 1-propenyl-2-phenyl Imidazole, 1-propenyl-4-
Phenylimidazole and the like can be mentioned.

Specific examples of the aliphatic tertiary amine include triethylamine, diethylaminopropylamine, diethylaminoethylamine, dimethylaminobenzylamine, 1,6-bis- (dimethylamino) -hexane, and triethanolamine. Further, specific examples of the aromatic tertiary amine include, in addition to N, N-dimethylaniline, N, N-dimethylbenzylamine, N, N-diethylbenzylamine, N, N-dimethylaminobenzaldehyde, Tris (dimethylaminomethyl) phenol and the like are also included, but are not limited thereto.

In the present invention, the amount of the component (D) to be added is not particularly limited and may be appropriately selected within a wide range. Usually, the total amount of the components (A), (B) and (C) is generally not limited. It is used in an amount of 0.05 to 8 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight.

On the other hand, the preparation of the resin composition for coating a rare earth permanent magnet of the present invention is carried out by the above-mentioned essential components (A) and (B).
And optionally the component (C) or (D) used by any method and, if necessary, as a solvent, toluene, xylene, methyl ethyl ketone, cyclohexanone, butyl cellosolve, butyl acetate, γ-butyrolactone, N-
Methyl-2-pyrrolidone, naphtha, or the like may be used alone or in combination of two or more, and may be uniformly mixed. Generally, it can be prepared by stirring and manufacturing with a disper or dispersion manufacturing with a sand mill.

In order to obtain the rare-earth permanent magnet of the present invention using the resin composition for coating a rare-earth permanent magnet of the present invention, the rare-earth permanent magnet is generally prepared by an arbitrary method such as air spray coating or dip coating. The surface of the permanent magnet may be coated with the resin composition of the present invention, and then the resin composition may be cured by heating. Specifically, the rare-earth permanent magnet coated with the resin composition of the present invention at a temperature of 80 to 400 ° C., preferably 120 to 350 ° C., for 0.005 to 5 hours, preferably 0.005 to 2 hours. By heating, the resin composition can be cured to form a film. In addition, the cured film is, if necessary, for example, at 150 to 350 ° C.
By performing the post-curing treatment for 0.5 to 3 hours, a stronger film can be obtained. If necessary, a drying treatment for removing the solvent (for example, at room temperature to 80 ° C. for 0.05 to 1 hour) may be performed before the heat curing.

The material of the magnet to which the resin composition for coating a rare earth permanent magnet of the present invention is applied is not particularly limited as long as it can be used as a rare earth permanent magnet, and the present invention coated with the resin composition is not particularly limited. Rare earth permanent magnets have excellent corrosion resistance, electrical insulation and heat resistance.

[0029]

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

The magnet body test piece is a 23.times.10 mm.times.6 mm composition of a 15.5Nd-77.5Fe-7B composition obtained by pulverizing a known casting ingot, finely pulverizing, forming, sintering, and heat-treating. Was used.

Each physical property was measured as follows. (1) Film thickness: The film thicknesses of the resin composition film and the metal film were measured by observing the fracture surface with an electron microscope. (2) Corrosion resistance: The corrosion resistance of each magnet body test piece having a resin coating was measured under the conditions of high temperature and high humidity at a temperature of 50 ° C. and a relative humidity of 90%. Evaluated by time. (3) Electrical Insulation: Electrodes were attached to the coated magnet test piece, the resistance between the coated surface and the magnet was measured, and evaluated by the volume resistivity obtained from the following equation (1). ρ = RS / 1 (1) (where ρ: volume resistivity Ω · cm, R: resistance Ω, S:
Electrode area cm ^2, l: coating thickness cm) (4) Heat resistance: Heat resistance of the coating was evaluated by heat distortion temperature, heat distortion temperature swelling of the coating was allowed to stand for 20 hours the temperature in the air, cracks Temperature.

Examples 1 to 6 and Comparative Examples 1 to 3 As bisalkenyl-substituted nadimides, bis {4- (allylbicyclo [2.2.1] hept-5-ene-2,3-
Dicarboxyimide) phenyl @ methane (Maruzen Petrochemical Co., Ltd .; hereinafter, abbreviated as "BANI-M") is used as a bisphenol-type epoxy resin as Epicoat 828 (Yuuka Shell Epoxy; hereinafter, abbreviated as "EP-828"), novolak Epicoat 180S65 (manufactured by Yuka Shell Epoxy; hereinafter abbreviated as "180S65") as a type epoxy resin and ADEKARESIN EPU-13 as a nitrogen-containing epoxy resin
48 (manufactured by Asahi Denka Kogyo; hereinafter abbreviated as "EPU-1348"), and polyether sulfone resin (manufactured by Sumitomo Chemical Co., Ltd .; PES-5003P;
ESR), polyphenylene sulfide resin (manufactured by Toray PPS, Inc .; M3910, hereinafter “PPSR”)
), 2-phenylimidazole as a curing catalyst, and Disparon # 1860 as a dispersant.
(Kusumoto Kasei Co., Ltd.) using xylene, methyl ethyl ketone or N-methyl-2-pyrrolidone (hereinafter "N
MP "), and stirred for 1 hour with a disper at a ratio (parts by weight) shown in Table 1 to produce a resin composition.
The magnet test piece was painted using a general air spray gun. After the coating, the test specimen was dried at room temperature for 10 minutes, and further heated and cured at 250 ° C. for 15 minutes to form a coating. The thickness of each of the formed resin composition films was 5 μm. The corrosion resistance, electric insulation and heat resistance were examined by the above-mentioned methods. Table 1 shows the results.

[0033]

[Table 1]

As is clear from Table 1, the magnet test pieces of Examples 1 to 6 using the resin composition of the present invention have good corrosion resistance, electrical insulation and heat resistance. It can be seen that, in the case of Comparative Examples 1 and 2 using a resin composition outside the scope of the present invention even with the above resin composition, the target of the present invention could not be obtained.

Examples 7 to 12 and Comparative Example 3 BANI-M as bisalkenyl-substituted nadimide, EP-828 as bisphenol type epoxy resin, 180S65 as novolak type epoxy resin, EPU-1348 as nitrogen-containing epoxy resin, PESR as polysulfone resin And carbon black (manufactured by Asahi Kasei Corporation; black 3078 [hereinafter referred to as “CB30
78 "] and Mitsubishi Kasei Kogyo; carbon black # 45 (hereinafter abbreviated as" CB45 ")), barium sulfate as an extender pigment (manufactured by Sakai Chemical Industry Co., Ltd .; precipitated barium sulfate # 100, hereinafter" barium sulfate ") Talc (manufactured by Nippon Talc Co., Ltd .; talc MS, hereinafter abbreviated as “talc”) and mica powder (manufactured by Yamaguchi Mica Industrial Co., Ltd .; mica A-1,
Hereinafter abbreviated as “mica powder”) and RH as an anti-settling agent.
EOX Inc. Benton 27 (hereinafter abbreviated as “anti-settling agent”) as Disparon # 1860 as a dispersant
Is mixed with 2-phenylimidazole as a curing catalyst and xylene, methyl ethyl ketone or NMP as a solvent at a ratio (parts by weight) shown in Table 2 by a sand mill for 2 hours to produce a resin composition. The magnet test piece was painted using a spray gun. After the coating, the test specimen was dried at room temperature for 10 minutes, and further heated and cured at 250 ° C. for 15 minutes to form a coating. The thickness of each of the formed resin composition films was 5 μm. Corrosion resistance, electrical insulation and heat resistance were examined in the same manner as in Examples 1 to 6 and Comparative Examples 1 and 2. Table 2 shows the results.

[0036]

[Table 2]

As is clear from Table 2, the magnetic body test pieces of Examples 7 to 12 using the resin composition of the present invention had good corrosion resistance, improved electrical insulation and heat resistance over those of Examples 1 to 6. It can be seen that in Comparative Example 3 using a resin composition outside the scope of the present invention even with the same type of resin composition, the object of the present invention cannot be obtained.

[0038]

According to the resin composition for coating a rare-earth permanent magnet of the present invention, an excellent method can be directly applied to the surface of a rare-earth permanent magnet by a simple method without going through complicated steps such as formation of a base metal film. The rare earth permanent magnet of the present invention coated with the resin composition has excellent corrosion resistance, electrical insulation, and excellent electrical insulation and heat resistance. It has heat resistance and heat resistance.

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[Procedure amendment]

[Submission date] August 11, 2000 (2008.1.
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction contents]

[0036]

[Table 2]

[Procedure amendment]

[Submission date] August 22, 2000 (2008.2.
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction contents]

[0033]

[Table 1]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction contents]

[0036]

[Table 2]

Claims (4)

[Claims] (A) General formula [1] [Wherein, R ^1, R ² are each independently selected hydrogen or a methyl group, R ³ is C alkylene group having ₂ ~ _20, C ₅ cycloalkylene group -C _8, 2-valent C ₆ -C ₁₂ An aromatic group of -A
_{a-C 6 H 4 -A '} - (a is an integer of 0 or 1, A, A'
Is an alkylene phenylene group represented by an independently selected C ₁ -C ₄ alkylene group), -C ₆ H ₄ -T-C ₆
H ₄ — (T represents a methylene group, an ethylidene group or a propylidene group). ], And a resin composition for coating a rare earth permanent magnet, comprising, as essential components, a bisalkenyl-substituted nadiimide represented by the formula (I) and (B) at least one of an epoxy resin, a polysulfone resin and a polyphenylene sulfide resin. 2. The rare earth system according to claim 1, wherein the content of the bisalkenyl-substituted nadimide (A) is 10 to 95% by weight based on the total weight of the resin components (A) and (B), which are essential components. A resin composition for coating a permanent magnet. 3. The rare earth according to claim 1, wherein the coloring pigment and / or extender are contained in a proportion of not more than 50% by weight based on the total weight of the resin components (A) and (B), which are essential components. -Based permanent magnet coating resin composition. 4. A rare earth permanent magnet whose surface is coated with the resin composition for coating a rare earth permanent magnet according to claim 1.