JPH0279404A - Polymer composite type rare magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent or remarkably reduce the oxidation from the surface of magnet powder particle so as to improve the deterioration of magnetic characteristics by using moisture setting type resin for polymer resin. CONSTITUTION:R2T14B (R is rare earth element including Y, T is transition metal) rare earth magnetic powder is made by refusing an ingot which is obtained by fusion and jetting fused alloy against a rotating roll, etc., so as to ultraquench it. Hereby, a liquid quenched alloy thin belt and a thin piece are formed, which are made into powder as there are by rough pulverization, or this thin belt and thin piece are made into a compact by hot-pressing. And hot plastic working is applied and further by roughly pulverizing it powder is formed. Next, this magnetic powder is binded with moisture setting type resin, and magnetic shape is maintained. Hereby, the oxidizing reaction from the surface of magnetic powder can be reduced remarkably, and deteriorations on standing of magnetic characteristics, etc., can be improved remarkably.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is particularly applicable to Nd-Fe-B polymer composite magnets, typically rubber magnets and plastic magnets.
Rare earth metals (R) and transition metals (represented by system permanent magnets)
Among the characteristics of a polymer composite rare earth magnet using R, T14B-based rare earth magnet powder containing T) and boron (B) as main components, this relates to improvement of deterioration due to chemotaxis over time.

[Prior Art] A polymer composite magnet is one in which magnet powder is dispersed in a polymer resin, or one in which magnet powder is aggregated with a polymer resin. This magnet has various characteristics not found in cast magnets, sintered magnets, etc., such as elasticity and workability, and is used in a variety of fields. however,
Since they are made of magnet powder and non-magnetic resin, they have the disadvantage of having lower magnetic properties than sintered magnets and the like.

Therefore, efforts are being made to achieve high magnetic properties by making the powder anisotropic, such as by orienting the powder in a magnetic field.

Various types of magnetic powder have been used to disperse and bind, but in the present invention, R2T, which is represented by the Nd-Fe-B system, which currently exhibits the highest magnetic properties, has been used.
14B magnet powder is used.

Conventional polymer composite magnets using rare earth magnet powder are manufactured by heat-treating and crushing an alloy ingot obtained by melting raw materials, mixing the powder with polymer resin, and molding it in a magnetic field. Ta. The magnet alloy powder used here was desirably composed of fine single-crystal particles in order to improve crystal orientation in a magnetic field.

However, R2 represented by Nd-Fe-B magnets
In the TIJB alloy, mechanical stress during crushing causes a decrease in coercive force (+Hc), so +Hc was significantly decreased in fine regions where the powder was composed of single crystal grains. Therefore, in a manufacturing method using a molten ingot as a starting material, even if a sintered magnet having a high Hc is crushed and used as magnet powder, the result is a polymer composite magnet that exhibits extremely poor magnetic properties. Moreover, in the method of manufacturing a polymer composite magnet by heat-treating an ingot and then pulverizing it to produce a polymer composite magnet, the magnet exhibits extremely poor magnetic properties that are worthless.

On the other hand, when pulverization causes almost no decrease in Hc, R
As a method for producing a -T-B magnetic alloy, a liquid quenching method has been known in which a molten alloy is injected onto a rotating roll or the like, and a magnetic alloy is obtained by ultra-quenching the alloy. However, it was not possible to achieve anisotropy with the powder obtained by this manufacturing method.

Subsequently, it was found that a magnetic powder capable of being anisotropic was obtained by hot plastic working this liquid quenched alloy.

R2T14B manufactured using these liquid quenching methods
The magnet powder consists of fine crystals (crystal grain size is 1 μm or less) and has high coercive force.

Since this method requires high temperature and high pressure, the equipment is expensive and large-scale, and there are concerns about stabilizing the properties in the manufacturing state. is still difficult to obtain, and it is difficult to say that it is industrially useful.

However, as a result of various experiments, the present inventor has found that even if powder obtained by crushing a sintered body is used, by appropriately selecting the crystal grain size and powder particle size, a sintered body with high magnetic properties can be obtained. We discovered that powder can be produced.

[Problems to be Solved by the Invention] Polymer composite magnets are composed of magnet powder and a polymer resin that binds the magnet powder and maintains its shape.

This resin is generally used for impregnating molds that impregnate the molded body with resin, and for compression molding molds that mix powder and resin and then compression mold them, such as epoxy resins. The injection mold is made of nylon resin or the like. However, polymer composite magnets made of these resins and magnet powder tend to deteriorate in magnetic properties over time. The main cause of these is oxidation from the surface of the magnet powder, and deterioration of characteristics is particularly accelerated at high temperatures and high humidity. This deterioration of properties due to oxidation is a serious defect in terms of quality. This tendency is also seen in the manufacturing method for pulverizing a sintered body discovered by the present inventor.

Therefore, it is extremely useful industrially to improve the deterioration of magnetic properties by preventing or significantly reducing oxidation from the surface of magnet powder particles.

Therefore, the technical problem of the present invention is to
The object of the present invention is to improve the aging deterioration of polymer composite magnets that can be manufactured by utilizing the manufacturing process of T-B based sintered magnets. Therefore, it is industrially very useful to use the polymer composite magnet and its manufacturing method.

[Means for solving the problem] According to the present invention. R2T14B system (R is a rare earth element containing Y, T is a transition metal) polymer composite rare earth magnet consisting of rare earth magnet powder and polymer resin, characterized in that the polymer resin is a moisture-curable resin. A polymer composite rare earth magnet is obtained.

According to the invention. R2T14B system (R is a rare earth element containing Y, T is a transition metal) rare earth magnet powder is mixed with a polymer resin, pressure molded, and hardened. A method for manufacturing a polymer composite rare earth magnet is obtained, which is characterized in that a moisture-curable resin is used as the resin. In the present invention, pressure molding refers to molding performed by applying pressure, such as compression molding, extrusion molding, and injection molding.

According to the invention. A method for producing a polymer composite rare earth magnet, which comprises molding R2T14B rare earth magnet powder (R is a rare earth element containing Y, T is a transition metal) and impregnating the resulting molded body with a moisture-curing resin. is obtained.

The present invention involves pulverizing an alloy ingot obtained by melting, and then sintering the powder compact obtained by compacting it in a magnetic field.
A sintered body with a high degree of crystal orientation is obtained, and then this sintered body is pulverized to a particle size within a range that can improve the magnetic properties, and then heat treated to improve the magnetic properties of the powder. The ingot obtained by melting is remelted, and the molten alloy is injected onto a rotating roll or the like and ultra-quenched to form liquid quenched alloy ribbons and flakes, and then coarsely pulverized to form powder, or The ribbons and flakes are hot pressed to form a molded body, followed by hot plastic working and further coarsely pulverized to form a powder. Thereafter, this magnet powder is condensed with a moisture-curable resin to maintain the magnet shape to produce a polymer composite magnet.

By constructing this polymer composite magnet from magnet powder and moisture-curable resin, oxidation reactions from the surface of the magnet powder can be significantly reduced, and deterioration over time of magnetic properties etc. can be significantly improved.

The R-T-B magnet alloy contains H as a main component, and contains rare earth elements, iron, etc., which are extremely susceptible to oxidation reactions. Therefore, the deterioration of magnetic properties due to oxidation reactions is more pronounced than in other metal magnets. The deterioration of magnet properties caused by this oxidation not only causes a simple decrease in the amount of magnetization, but also significantly affects the magnetization process, resulting in a decrease in the squareness of the demagnetization curve, a decrease in coercive force, and deterioration of various magnet properties. is related to.

Since the oxidation reaction proceeds from the surface of the alloy,
If the magnetic alloy is in powder form, its specific surface area is inversely proportional to the square of the particle radius, so the deterioration of characteristics due to oxidation becomes significant. Oxidation of this alloy is strongly related to the amount of oxygen and moisture in the atmosphere in which the alloy is handled during normal manufacturing processes. In addition, the surface of the powder obtained by pulverization etc. is active, so it adsorbs oxygen, moisture, etc.
These oxidizing factors are not removed by inert gas replacement or the like. Therefore, if kept in this state for a long time, oxidation will progress and the magnetic properties will deteriorate over time. Such a tendency is observed in epoxy resin, nylon, etc., which have been commonly used in conventional polymer composite magnets. This tendency is accelerated by holding at high temperature and high humidity.

As a result of various experiments, the inventor of the present invention found that by using a moisture-curing resin as the resin constituting the polymer composite magnet, the magnetic properties deteriorate significantly over time compared to conventionally commonly used resins. I found that it can be improved. The reason for this is that the moisture-curable resin reacts with moisture adsorbed on the surface of the magnet powder and hardening progresses, so that the adsorbed moisture, which is an oxidizing factor, is removed from the surface of the magnet powder.

In addition, the moisture that enters from the atmosphere in which the polymer composite magnet is held reacts with extremely small amounts of unreacted components remaining in the resin, so oxidation of the surface of the magnet powder can be significantly reduced.

Examples will be described below.

Example 1 Cerium didymium consisting of 5 wL% Ce, 15 wt% P, the balance Nd (however, other rare earth elements were included as Nd), Dy with a purity of 99 wt% or more, ferroboron (B pure fraction) 20wt%) and electrolytic iron.
-Pr-Nd) is 31. .

vt%, Dy is 3. Ovt%, B is 1. Ovt%, balance Fe, was melted by high frequency heating in an argon atmosphere to obtain an alloy ingot.

Next, this ingot was coarsely ground, and then finely ground to an average diameter of about 2 μm using a ball mill.

This alloy powder was mixed at 1 ton/in a magnetic field of about 20 KOe.
It was molded into a rectangular parallelepiped at a pressure of e1 m2. Next, this molded body was held in vacuum at 1000° C. for 1 hour and then in Ar for 3 hours to obtain a sintered body. The sintered density of these is approximately 7. 5
5gr/all+3, and the average crystal grain size was approximately 5 μm.

Next, this sintered body was coarsely ground to an average particle size of 30 μm, and then heat treated at 600° C. in vacuum for 1 hour and in Ar for 94 hours. Next, after crushing these heat-treated powders in the atmosphere at an air temperature of 20°C and a relative temperature of 6096, approximately 20KOe
It was formed into a disk shape under a magnetic field of 3'tOn/e12. The space factor of the magnet powder in this compacted powder sample was about 65 vt%.

Next, after vacuuming these molded bodies, they were impregnated with epoxy resin, moisture-curing methyl cyanoacrylate, and silicone rubber resin, and then held at 80°C for 5 hours to harden, forming a polymer composite magnet. .

Next, this polymer composite magnet was kept in a constant temperature and humidity chamber at a temperature of 60°C and a relative temperature of 90% for 1000 hours, and then
Magnetic properties were measured by applying a KOe magnetic field. The demagnetization curve (4πI-H curve) is shown in FIG. Compared to the sample impregnated and cured with an epoxy resin, the sample impregnated and cured with moisture-curable methyl cyanoacrylate and silicone rubber resin shows a tendency for deterioration over time to be clearly smaller. The magnetic properties of these samples are shown in Table 1.

Below is the margin Example 2 Nd with a purity of 97% or more (the remainder is rare earth elements mainly consisting of Ce and Pr), ferroboron (purity of about 20vL%)
, electrolytic iron, electrolytic cobalt, and aluminum were used in the same manner as in Example 1, Nd was 35, OvL%, and B was 1.
An ingot was obtained having a composition of 0 w1%, CO 10 v[%], A, 9 1 wt%, and the balance Fe.

Next, using this ingot, pulverization, compaction in a magnetic field, and sintering at 980° C. were performed in the same manner as in Example 1.

The density of these sintered bodies was about 7°50 gr/cm3, and the average crystal grain size was about 4.5 μm.

Next, after coarsely pulverizing these sintered bodies, they were classified using a sieve to obtain powder in the range of 26 to 300 μm.

Next, this powder was heat treated at 600°C for 2 hours.

Next, these powders were crushed in the same manner as in Example 1, and then
The powder was mixed with 30Vo1% epoxy resin, moisture-curing ethyl cyanoacrylate, and polyurethane resin, and molded in a magnetic field. 80% of the molded body
It was held at ℃ for 10 hours to be cured to obtain a polymer composite magnet.

Next, this magnet was held in a constant temperature and high humidity bath in the same manner as in Example 1, and then the magnet characteristics were determined by IIP1. The demagnetization curve (4πI-H curve) is shown in FIG.

Compared to the sample that was mixed and cured with an epoxy resin, the sample that was cured with a mixture of moisture-curable ethyl cyanoacrylate and polyurethane resin showed a clearly smaller tendency to change over time. The magnetic properties of these samples are shown in Table 2.

Below are blank spaces Example 3: Cerium dididium consisting of 5 wt% Ce, 15 wt% P, the balance Nd (however, other rare earth elements were included as Nd), ferroboron (B pure content about 20 wt96),
Using electrolytic cobalt and electrolytic iron, (Ce-PrφNd
) is 31. Ovt%, CO is 10, Ovt%, B is 1.
Ovt%, balance Fe, was melted by high frequency heating in an argon atmosphere to obtain an alloy ingot.

Next, this ingot was remelted by high-frequency heating in an Ar atmosphere, and then sprayed onto a Cu roll with a circumferential speed of about 35 m/see to form liquid quenched alloy ribbons and flakes with a thickness of about 20 μm and a width of about 3II11. Obtained.

Next, this liquid quenched alloy was heated at 600°C in an Ar atmosphere for 2 hours.
After holding for a period of time, it was ground to 180 μm or less. This powder was molded into a disk shape under a pressure of 2 Lon/c- in the absence of a magnetic field. The space factor of the magnet powder in this compacted powder sample was approximately 68 vol%.

Next, these molded bodies were evacuated and impregnated with epoxy resin, moisture-curable methyl cyanoacrylate, and silicone rubber-based resin, and then held at 80° C. for 5 hours to harden to obtain a polymer composite magnet.

Next, this polymer composite magnet was kept in a constant temperature and humidity chamber at a temperature of 60°C and a relative temperature of 90% for 1000 hours, and then
Magnetic properties were measured by applying a KOe magnetic field. The demagnetization curve (4πI-H curve) is shown in FIG. Compared to samples impregnated and cured with epoxy resin, samples impregnated and cured with moisture-curable methyl cyanoacrylate and silicone rubber-based resins show a tendency for the deterioration of magnetic properties over time to be clearly smaller. The magnetic properties of these samples are shown in Table 3.

Below are blank spaces Example 4 Nd with a purity of 97 wt% or more (the remainder is rare earth elements mainly consisting of Ce and Pr), ferroboron (B purity about 20 wt%)
), electrolytic iron was used, and Nd was 32 in the same manner as in Example 3.
．． After obtaining an ingot containing 0 wt% B, 1.0 wt% B, and the balance Fe, liquid quenched alloy ribbons and flakes were obtained.

Next, this liquid rapidly solidified alloy was coarsely pulverized to 300 μm or less, and then hot pressed at 700° C. and a pressure of 1 ton/C− in an Ar atmosphere to obtain a molded body. This density is about 7.
It was 50gr/cmI. Next, this molded body was
700°C in r atmosphere, 1. ．． Hot plastic working was performed by applying pressure in the uniaxial direction at a pressure of 5 ton/C- so that the 11 dimension in the pressing direction was approximately 115.

This processed molded product exhibited white magnetic anisotropy in the direction of pressure, and was composed of laminated plate-shaped crystals with a crystal grain size of about 0.3 μm and a thickness of about 0.1 μm.

Next, after coarsely pulverizing the second hot-processed compact to 300 μm or less, 30 vol of 96 epoxy resin, moisture-curable ethyl cyanoacrylate, and polyurethane resin were mixed with the powder, and a magnetic field of about 20 KOe was applied. Medium, 1.
Molding was carried out in a magnetic field at a pressure of 5 tons/c-. This molded body was held at 80° C. for 10 hours and cured to form a polymer composite magnet.

Next, this magnet was held in a constant temperature and high humidity bath in the same manner as in Example 3, and then the magnetic properties were measured. Its demagnetization curve (4
πI-H curve) is shown in FIG.

Compared to the sample obtained by mixing and curing an epoxy resin, the sample obtained by mixing and curing a moisture-curable ethyl cyanoacrylate and polyurethane resin shows a tendency for the change over time to be clearly smaller. The magnetic properties of these samples are shown in Table 4.

As shown in the examples in the following margins, polymer composite type R, T1
4B rare earth magnet. By using the R, T14B sintered powder and the moisture curing resin, deterioration of magnetic properties over time can be significantly improved.

In the above embodiments, Ce-P r-Nd-Co -Fe
-B system, Nd-Fe-B system, Ce-Pr-Nd-Dy-
Although only the Fe-B system and the Nd-Fe-Co-Afi-B system have been described, some of the Nd may be replaced with Y and other rare earth elements such as Gd, Tb, Ho, etc., or some of the Fe may be replaced with Substitution with other transition metals such as Mn, Cr, Ni, etc., or B
Even if a part of is replaced with other semi-metals such as St, C, etc., the composition of the magnet alloy will still have Nd-Fe-B as a main component, and the magnetic compound system will be represented by the Nd2Fe14B system. It can be easily inferred that the effects of the present invention can be fully expected if R2T14B such as R2T14B or a similarly chemically active compound contributes to magnetism.

Furthermore, in the present invention, only methyl cyanoacrylate, ethyl cyanoacrylate, silicone rubber-based, and polyurethane-based resins have been described as moisture-curable resins.
The present invention can be interpreted to include any product within this range as long as the curing of the resin progresses by reacting with moisture.

In addition, regarding the manufacturing method of polymer composite magnetization shown in this example, only the impregnation type in which the molded body is impregnated with resin and the compression molding type in which powder and resin are mixed and then compression molded are described. Those skilled in the art can easily imagine that the present invention can also be applied to molding methods such as injection molding and extrusion molding.

[Effects of the Invention] As can be seen from the above description, the present invention does not require changing the properties of the magnet powder constituting the polymer composite magnet, and the magnet It can significantly improve the deterioration of characteristics over time, and is industrially useful.
Very informative.

[Brief explanation of the drawing]

FIG. 1 is a demagnetization curve (4πI-H curve) after aging of the polymer composite magnet in Example, where the solid line is methyl cyanoacrylate resin, the dashed line is silicone rubber system, and the dashed line is silicone rubber system.
The dotted line is a diagram showing a sample using an epoxy system (comparative example). FIG. 2 shows the demagnetization curve (4πI-H curve) of the polymer composite magnet in Example 2 after aging, where the solid line is ethyl cyanoacrylate, the dashed line is polyurethane, and the dotted line is epoxy ( FIG. 3 is a diagram showing a sample using Comparative Example). FIG. 3 is a demagnetization curve (4πI-H curve) after aging of the polymer composite magnet in Example 3. In the figure, the solid line is methyl cyanoacrylate resin, the dashed line is silicone rubber system, and the dotted line is is a diagram showing a sample using an epoxy system (comparative example). FIG. 4 is a demagnetization curve (4πl-14 curve) after aging of the polymer composite magnet in Example 4. In the figure, the solid line is ethyl cyanoacrylate, the dashed line is polyurethane, and the dotted line is polyurethane. is a diagram showing a sample using an epoxy system (comparative example). Figure 2 H (in Oe)

Claims (3)

[Claims] 1. R_2T_1_4B system (R is a rare earth element containing Y,
T is a transition metal) In a polymer composite rare earth magnet consisting of a rare earth magnet powder and a polymer resin, the polymer resin is
A polymer composite rare earth magnet characterized by being made of moisture-curing resin. 2. R_2T_1_4B system (R is a rare earth element containing Y,
T is a transition metal) A method for producing a polymer composite rare earth magnet in which rare earth magnet powder is mixed with a polymer resin, pressure molded, and hardened, characterized in that a moisture-curable resin is used as the polymer resin. A method for manufacturing a polymer composite rare earth magnet. 3. R_2T_1_4B system (R is a rare earth element containing Y,
A method for producing a polymer composite rare earth magnet, which comprises molding rare earth magnet powder (T is a transition metal) and impregnating the obtained molded body with a moisture-curing resin.