JP2003332162A - Method of coating aqueous treating liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which an aqueous treating liquid can be coated inexpensively and evenly to the surface of a single plate-shaped rare- earth permanent magnet piece. <P>SOLUTION: In this method, a coating film of prescribed coverage is formed on the surface of the single plate-shaped rare-earth permanent magnet piece housed in a wire-net holder by performing (a) the application of the aqueous treating liquid, (b) first gas wiping at an injection pressure of 0.01-0.1 MPa, and (c) second gas wiping at an injection pressure higher than that of the first gas wiping in this order from the upside and downside of the holder while the holder is carried in a horizontal direction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for uniformly applying a water-based treatment liquid onto the surfaces of individual plate-shaped rare earth permanent magnet pieces at low cost.

[0002]

2. Description of the Related Art Rare-earth magnets such as R-Fe-B permanent magnets represented by Nd-Fe-B permanent magnets and R-Fe-N permanent magnets represented by Sm-Fe-N permanent magnets. Permanent magnets are made of inexpensive and resource-rich materials, and
R-Fe-B in particular because of its high magnetic properties
System permanent magnets are used in various fields today. However, rare-earth permanent magnets are highly reactive rare-earth metals:
Since it contains R, it is easily oxidatively corroded in the atmosphere, and when used without any surface treatment, corrosion progresses from the surface due to the presence of a slight amount of acid, alkali or moisture, and rust occurs. As a result, deterioration or variation in magnet characteristics is caused. Furthermore, when a magnet with rust is incorporated in a device such as a magnetic circuit, the rust may scatter to contaminate peripheral parts. Therefore, it has long been practiced to form a corrosion resistant coating on the surface of a rare earth permanent magnet.

[0003]

The plate-shaped rare earth-based permanent magnet pieces (flat plate pieces, bow-shaped pieces, etc.) are generally used for various motors, but most of them are 5 mm in length and width. It is about 10 cm. In order to promote cost reduction at the manufacturing site where a corrosion resistant coating is formed on the surface of such a magnet piece, how to uniformly form a corrosion resistant coating on each surface of a large number of magnet pieces at a low cost? The point becomes a big technical problem. Above all, a corrosion resistant coating formed by using an aqueous treatment liquid, for example, a glassy coating containing an alkali silicate as a constituent component, an inorganic acid (phosphoric acid, chromic acid, etc.) or an organic acid (oxalic acid, citric acid, etc.) In the case of forming a chemical conversion treatment film containing as a constituent on the surface of the individual magnet piece, there is a problem that it is difficult to dry because the treatment liquid applied to the surface is aqueous. If such treatment liquid applied to the surface of the magnet piece stays for a long time without drying, it may lead to corrosion of the magnet or excessively adhered treatment liquid may be formed on the end or side of the magnet piece. To do. If an excessively adhered portion of the treatment liquid is formed on the surface of each magnet piece, the subsequent baking step may cause fine cracking of the coating film on that portion, resulting in uniform appearance and corrosion resistance. May be damaged. Therefore, it is very significant to develop a method for uniformly coating the surface of the plate-shaped rare earth-based permanent magnet piece with the aqueous treatment liquid at low cost. Therefore, it is an object of the present invention to provide a method for uniformly applying an aqueous treatment liquid onto the surface of a piece of plate-shaped rare earth-based permanent magnet at low cost.

[0004]

The method for applying the aqueous treatment liquid of the present invention made in view of the above points is, as described in claim 1, a plate-shaped rare earth-based permanent magnet piece conveyed horizontally. From the upper and lower sides of the housed wire mesh holder, (a) application of the aqueous treatment liquid, (b) injection pressure of 0.01M.
A plate-shaped rare earth permanent magnet housed in a wire mesh holder by sequentially performing first gas wiping at Pa to 0.1 MPa and (c) second gas wiping at an injection pressure higher than the injection pressure of the first gas wiping. It is characterized in that a predetermined amount of coating film is formed on the surface of each piece. In addition, the coating method according to claim 2 is the same as the coating method according to claim 1, in which the injection pressure is 0.1.
The second gas wiping is performed at MPa to 0.5 MPa. Further, the coating method according to claim 3 is the coating method according to claim 1 or 2, wherein air is blown from a nozzle provided at an angle of 1 ° to 30 ° in a direction opposite to the conveying direction of the wire mesh holder. Thus, the first gas wiping and / or the second gas wiping is performed. The coating method according to claim 4 is characterized in that, in the coating method according to any one of claims 1 to 3, the transport speed of the wire mesh holder is 20 cm / min to 300 cm / min. The coating method according to claim 5 is the coating method according to any one of claims 1 to 4, wherein the wire mesh holder is a crimp wire mesh holder. A coating method according to claim 6 is the coating method according to any one of claims 1 to 5, characterized in that the first gas wiping and the second gas wiping are performed in different compartments. The coating method according to claim 7 is the coating method according to any one of claims 1 to 6, wherein the aqueous treatment liquid is a treatment liquid for forming a corrosion-resistant coating. The coating device for forming a coating film of a predetermined amount of the aqueous treatment liquid on the surface of the plate-shaped rare earth-based permanent magnet piece according to the present invention is, as described in claim 8, the plate-shaped rare-earth-based permanent magnet piece. Transporting means for horizontally transporting the wire netting holder that contains therein, and (a) an application means for the aqueous treatment liquid, which is sequentially applied to the wire netting holder horizontally transported, from above and below. (B) First means for performing gas wiping at an injection pressure of 0.01 MPa to 0.1 MPa, (c) second means for performing gas wiping at an injection pressure higher than the injection pressure of gas wiping by the first means. , Are provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The method for applying a water-based treatment liquid according to the present invention comprises: (a) a wire mesh holder containing plate-shaped rare earth-based permanent magnet pieces conveyed in a horizontal direction from above and below. Application of water-based treatment liquid, (b) injection pressure 0.01M
A plate-shaped rare earth permanent magnet housed in a wire mesh holder by sequentially performing first gas wiping at Pa to 0.1 MPa and (c) second gas wiping at an injection pressure higher than the injection pressure of the first gas wiping. It is characterized in that a predetermined amount of coating film is formed on the surface of each piece. According to the method for applying a water-based treatment liquid of the present invention, a wire mesh holder accommodating individual pieces of plate-shaped rare earth-based permanent magnets coated with a water-based treatment liquid over the entire surface thereof is first and Gas wiping is performed at a low injection pressure such as 0.01 MPa to 0.1 MPa to roughly wipe the treatment liquid excessively attached to the surface of the magnet piece, and then the injection pressure higher than the injection pressure of the first gas wiping is applied. The second gas wiping is performed by pressure to surely wipe the excess processing liquid remaining on the end or side surface of the magnet piece to prevent formation of an excessively adhered portion of the processing solution and to the surface of the magnet piece. The coating amount of the treatment liquid is adjusted to obtain a coating film having a predetermined coating amount. As a result, it becomes possible to uniformly apply, at a low cost, the water-based treatment liquid that is difficult to dry onto the individual surfaces of a large number of plate-shaped rare earth-based permanent magnet pieces at one time.

As the aqueous treatment liquid applied to the surface of the plate-shaped rare earth-based permanent magnet piece, a treatment liquid for forming a corrosion resistant coating, for example, a glassy coating containing an alkali silicate as a constituent component, an inorganic acid (phosphorus) is used. Acids, chromic acid, etc.) and organic acids (oxalic acid, citric acid, etc.) are used as treatment liquids for forming a chemical conversion treatment film. Specifically, as a treatment liquid for forming a glassy film, there is disclosed in Japanese Patent Laid-Open No.
The treatment liquids described in JP-A-7867, JP-A No. 11-251121, Japanese Patent Application No. 2001-344527 and the like are mentioned, and as a treatment liquid for forming a chemical conversion coating, Japanese Patent No. 317597 or Japanese Patent Application 2001-
The treatment solutions described in the specification of No. 225218 and the like can be mentioned. The treatment liquid for forming the corrosion resistant coating may be a water-soluble resin such as an acrylic resin coating or a urethane resin coating. The aqueous treatment liquid applied to the surface of the plate-shaped rare earth-based permanent magnet piece may be an aqueous solution containing a rust preventive agent.

The coating method of the aqueous treatment liquid of the present invention will be described below with reference to the drawings as necessary.

FIG. 1 is a schematic view of one embodiment of a coating apparatus suitable for carrying out the coating method for an aqueous treatment liquid of the present invention. The plate-shaped rare earth-based permanent magnet piece 1 that is the object to be processed is housed in the wire mesh holder 2, and the wire-mesh holder 2 that contains the plate-shaped rare earth-based permanent magnet piece 1 horizontally moves the wire mesh holder 2 in the horizontal direction. It is placed on a roller 3 as a conveying means for conveying and is conveyed from the right-hand direction to the left-hand direction in the drawing. The transport speed of the wire mesh holder 2 is 20 cm / min to 30
0 cm / min is desirable, 30 cm / min to 20
0 cm / min is more preferable, and 50 cm / min-
170 cm / min is more desirable. If the transport speed is too slow, air may be excessively blown against the magnet pieces, causing uneven treatment liquid adhesion on the surface, while if too fast, a sufficient wiping effect may not be obtained and the magnet pieces may not be obtained. This is because there is a possibility that an excessively adhered portion of the processing liquid may be formed on the end portion or the side surface of the piece.

First, an aqueous treatment liquid is applied to the wire mesh holder 2 accommodating the plate-shaped rare earth-based permanent magnet pieces 1 from above and below by a coating means using a shower nozzle 4. The coating means may be any other known means.

Next, a gas wiping means using a blower nozzle 5 is used to spray the metal mesh holder 2 containing the plate-shaped rare earth permanent magnet pieces 1 having the entire surface coated with the aqueous treatment liquid from above and below. Pressure 0.01MPa ~
The first gas wiping is performed at 0.1 MPa to roughly wipe the treatment liquid excessively attached to the surface of the plate-shaped rare earth-based permanent magnet piece 1. The distance from the air ejection port of the nozzle to the surface of the magnet piece is preferably adjusted to 10 mm to 70 mm, more preferably 15 mm to 30 mm for the purpose of obtaining a uniform wiping effect. The gas wiping means may be other known means. The reason why the injection pressure of the first gas wiping is regulated in this way is that the wiping effect is not sufficiently obtained when the pressure is less than 0.01 MPa, while the pressure is excessively attached to the surface of the magnet piece when the pressure exceeds 0.1 MPa. This is because it is difficult to uniformly wipe the liquid, and a large amount of the processing liquid scatters and adheres to the surface of another magnet piece or adheres to the wall surface of the processing chamber.

When performing the first gas wiping, the blower nozzle 5 for blowing air is set at 1 ° to 30 ° in the direction opposite to the conveying direction of the wire mesh holder 2 accommodating the plate-shaped rare earth permanent magnet piece 1. It is desirable to provide it at an angle θ ₁ and to blow air from a nozzle.
By defining the lower limit of the angle θ ₁ as 1 °, the air blown from the nozzle flows in the direction opposite to the conveying direction of the magnet piece, and the treatment liquid excessively attached to the surface of the magnet piece is moved backward. Since wiping is performed by pushing it to, it is easy to obtain a sufficient wiping effect. The upper limit of the angle θ ₁ is defined as 30 °, because when the angle exceeds 30 °, the air blown from the nozzle strongly hits the side of the magnet piece facing the conveying direction, so that the magnet piece inside the wire mesh holder is pressed. This is because the pieces may slide or the like, and when the plurality of magnet pieces are housed in the wire mesh holder, the magnet pieces may collide with each other or overlap each other.

Next, the injection pressure is 0.01 MPa to 0.1 M.
For the metal mesh holder 2 containing the plate-shaped rare earth-based permanent magnet pieces 1 subjected to the first gas wiping at Pa, the gas wiping means using the wiping nozzle 6 is used to perform the first gas wiping from above and below. The second gas wiping is performed at a higher injection pressure than the injection pressure to reliably wipe excess processing liquid remaining on the end or side surface of the magnet piece to prevent the formation of an excessively adhered portion of the processing liquid. The coating amount of the predetermined coating amount is adjusted by adjusting the coating amount of the treatment liquid on the surface of each magnet piece. The distance from the air ejection port of the nozzle to the surface of the magnet piece is preferably adjusted to 10 mm to 70 mm, more preferably 15 mm to 30 mm for the purpose of obtaining a uniform wiping effect. The gas wiping means may be other known means. Injection pressure is 0.1M for the second gas wiping
It is desirable to carry out at Pa to 0.5 MPa. 0.1MP
If it is less than a, a sufficient wiping effect may not be obtained and an excessive amount of the treatment liquid may be formed on the end portion or side surface of the magnet piece, while if it exceeds 0.5 MPa, the magnet piece may be conveyed in the conveying direction. This is because the air blown from the nozzle strongly hits the facing side surface, which may cause the magnet pieces to slide inside the wire mesh holder.

When performing the second gas wiping, the wiping nozzle 6 for blowing air is 1 ° to 30 ° in the direction opposite to the conveying direction of the wire mesh holder 2 accommodating the plate-shaped rare earth permanent magnet individual piece 1. It is desirable that the angle θ ₂ is set and the air is blown from the nozzle. The lower limit of the angle θ ₂ is defined as 1 °. If the angle is less than 1 °, the treatment liquid is scattered in the transport direction of the wire mesh holder, and a magnet having a predetermined amount of coating film already formed on the surface of the magnet. This is because the treatment liquid may redeposit on the surfaces of the individual coating films. In addition, the upper limit of the angle θ ₂ is defined as 30 °, because when the angle exceeds 2 °, the air blown from the nozzle strongly hits the side surface of the magnet piece facing the conveying direction, so that the inside of the wire mesh holder is This is because the individual magnet pieces may slide.

The wire mesh holder for accommodating the individual pieces of the plate-shaped rare earth-based permanent magnet may be made of any kind of wire mesh, but among them, a crimp wire mesh (a corrugated curve is applied to a metal wire is used. , A wire mesh having a mesh structure by intertwining vertical and horizontal lines: For example, a wire diameter φ1.0 mm and an opening 1
Those having a size of 0 mm × 10 mm) are preferably used. If a wire mesh holder made of crimp wire mesh is used, the contact between the magnet piece placed on the wire mesh and the wire mesh will be point contact, so in addition to the small contact point between the two, gas wiping is also performed. When this happens, the air blown from the nozzle causes the magnet pieces to move slightly, so the contact points between the magnets are not fixed.Therefore, there is a trace of contact points with the wire mesh on the surface of the coating film with a certain amount of coating formed on the surface of the magnet pieces. This is because there is an advantage that the air does not remain, and that the air blown from the nozzle can efficiently flow to the bottom surface of the magnet piece, and effective wiping can be performed (see an enlarged view in FIG. 1).

As shown in FIG. 1, the first gas wiping and the second gas wiping are performed so that the processing liquid scattered when the second gas wiping is performed does not adversely affect the first gas wiping performed upstream thereof. Are done in different compartments,
It is desirable to block both compartments with a processing liquid scattering prevention wall 7.

For the individual pieces of the plate-shaped rare earth magnet body whose surface is uniformly coated with the aqueous treatment liquid, the required steps may be carried out thereafter. When the water-based treatment liquid is a treatment liquid for forming a corrosion-resistant coating, a baking process is performed according to each treatment liquid, but according to the present invention, the treatment liquid is uniformly applied to the surface of the magnet piece. Therefore, there is no excessive portion of the treatment liquid attached to the surface of each magnet piece. Therefore, even if the baking process is performed, fine cracks of the coating film do not occur, and thus the uniformity of appearance and the corrosion resistance are not impaired.

[0017]

EXAMPLES The coating method of the aqueous treatment liquid of the present invention will be described in detail below with reference to examples, but the present invention is not construed as being limited to the following description.

For example, as described in US Pat. No. 4,770,723 and US Pat. No. 4,792,368, a known casting ingot is crushed and finely crushed, and then obtained by molding, sintering, heat treatment and surface processing. Lithium silicate 10 was formed on the surface of a flat plate-shaped sintered magnet piece (hereinafter, simply referred to as a magnet piece) having a size of 30 mm in length × 20 mm in width × 3 mm in height having a composition of 14Nd-79Fe-6B-1Co (at%). Glass-like corrosion resistant coating using a water-based treatment liquid containing 2.5% by weight of soap-free water-soluble emulsion type acrylic styrene resin (using Asahi Kasei Kogyo Co., Ltd., trade name F-2000) Was formed. As the coating device, a coating device having the configuration shown in FIG. 1 (θ ₁ = θ ₂ = 5 ° and the distance from the air ejection port of the nozzle to the surface of the magnet piece adjusted to 20 mm) was used.
The magnet pieces were housed in a crimp wire mesh holder and conveyed.
The baking process after applying the treatment liquid to the surface of each magnet piece is 20
It was set to 0 ° C. for 20 minutes.

Experiment 1: The transfer speed of the holder was 150 cm /
Min, the injection pressure of the first gas wiping is 0.02 MPa, the injection pressure of the second gas wiping is 0.05 MPa, 0.2M
After the aqueous treatment liquid was applied to the surface of each magnet piece under three conditions of Pa and 0.4 MPa, a baking process was performed to form a glass-like corrosion resistant coating, and the appearance of 50 randomly sampled samples was evaluated. . The results are shown in Table 1.

[0020]

[Table 1]

As is clear from Table 1, when the injection pressure of the second gas wiping is set to 0.05 MPa, the appearance defect due to insufficient injection pressure (fine cracking of the coating film resulting from the formation of the excessively adhered portion of the treatment liquid) ) There were a few samples,
When the pressure was 0.2 MPa and the pressure was 0.4 MPa, there were no samples with poor appearance.

Experiment 2: The injection pressure of the first gas wiping was 0.02 MPa and the injection pressure of the second gas wiping was 0.2.
MPa, holder transport speed 30 cm / min, 60 cm /
Min, 120 cm / min, 150 cm / min, 200 cm / min under the following conditions:
A baking process was performed to form a glass-like corrosion resistant film, and the appearance of 50 randomly sampled samples was evaluated. The results are shown in Table 2.

[0023]

[Table 2]

As is clear from Table 2, when the holder conveying speed is 30 cm / min, there are a small number of samples with poor appearance (uneven coating film caused by uneven adhesion of the treatment liquid) due to the low conveying speed. did. In addition, when the transport speed of the holder was set to 200 cm / min, there were a small number of samples with poor appearance (fine cracks in the coating film resulting from the formation of the excessively adhered portion of the treatment liquid) due to the high transport speed. However, the holder transfer speed is 60 cm / min, 120 c
At m / min and 150 cm / min, there were no samples with poor appearance.

[0025]

According to the present invention, there is provided a method for uniformly applying a water-based treatment liquid onto the surfaces of individual plate-shaped rare earth permanent magnet pieces at low cost.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of a coating apparatus suitable for carrying out the coating method for an aqueous treatment liquid of the present invention.

[Explanation of symbols]

1 Pieces of plate-shaped rare earth-based permanent magnet 2 Wire mesh holder 3 roller 4 shower nozzles 5 blower nozzle 6 Wiping nozzle 7 Treatment liquid scattering prevention wall

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Claims (8)

[Claims] 1. A metal mesh holder containing plate-shaped rare earth-based permanent magnet pieces conveyed in the horizontal direction, from above and below, (a) application of an aqueous treatment liquid, (b) injection pressure of 0. A plate-shaped rare earth permanent magnet housed in a wire mesh holder by sequentially performing first gas wiping at 01 MPa to 0.1 MPa and (c) second gas wiping at an injection pressure higher than the injection pressure of the first gas wiping. A method for applying an aqueous treatment liquid, which comprises forming a coating film of a predetermined amount on the surface of each piece. 2. The coating method according to claim 1, wherein the second gas wiping is performed at an injection pressure of 0.1 MPa to 0.5 MPa. 3. A wire mesh holder is mounted in a direction opposite to the carrying direction.
3. The coating method according to claim 1, wherein the first gas wiping and / or the second gas wiping is performed by blowing air from a nozzle provided at an angle of 30 ° to 30 °. 4. The coating method according to any one of claims 1 to 3, wherein the transport speed of the wire mesh holder is 20 cm / min to 300 cm / min. 5. The coating method according to claim 1, wherein the wire mesh holder is a crimp wire mesh holder. 6. The coating method according to claim 1, wherein the first gas wiping and the second gas wiping are performed in different compartments. 7. The coating method according to claim 1, wherein the aqueous treatment liquid is a treatment liquid for forming a corrosion resistant film. 8. A coating device for forming a coating film of a predetermined adhesion amount of an aqueous treatment liquid on the surface of a piece of plate-shaped rare earth-based permanent magnet, which is made of a wire mesh containing the piece of plate-shaped rare earth-based permanent magnet. (A) a coating means for the aqueous treatment liquid, which is applied in order from the upper side and the lower side of the wire mesh holder that is horizontally transported, the transport means for horizontally transporting the holder,
(B) First means for performing gas wiping at an injection pressure of 0.01 MPa to 0.1 MPa, (c) second means for performing gas wiping at an injection pressure higher than the injection pressure of gas wiping by the first means. And a coating device.