JPH04286302A - Composition for rare earth-fe-b bonded magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a rare earth-Fe-B bonded magnet composition, having excellent powder feeding property for a mold and also having excellent magnetic characteristics, and the manufacturing method thereof when it is molded into a magnet through compression molding requiring no high molding pressure without shortening the life of the mold. CONSTITUTION:An alloy thin band, having the composition in atomic ratio of 12.2% of rare earth, 76.8% of Fe, 5.5% of Co and 4.9% of B, is formed using a copper roll which rotates at rotational speed of 20m/sec. This alloy thin band is granulated by a stamping mill into powder which passes through 35 meshes entirely. The granulated powder is vibratory pulverized on a screen of 80 to 100 meshes together with spheres. An epoxy resin binder of 0.5 to 2.5 pts.wt. is added to the above-mentioned powder of 100 pts.wt., and a rare earth-Fe-B bonded composition, with which the objective effect can be displayed, is manufactured.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a rare earth-Fe-B bonded magnet composition for producing a rare earth-Fe-B bonded magnet with excellent powder feeding properties, moldability, and magnetic properties, and its production. It is about the method.

0002

2. Description of the Related Art Due to their excellent magnetic properties, rare earth-Fe-B permanent magnets are being applied in a wide range of fields including general home appliances, communication and audio equipment, medical equipment, and general industrial equipment. There are two types of magnets of this type: a bonded type obtained by compression molding or injection molding using a thermosetting resin or thermoplastic resin as a binder, and a sintered type obtained by sintering heat treatment of alloy powder. Among them, bond type magnets have lower magnetic properties than sintered type magnets, but they do not require processing such as sintering, and magnets with complex shapes and thin walls can be easily created. recent years,
Demand is rapidly increasing.

[0003] For this purpose, a composition for a rare earth-Fe-B bonded magnet (hereinafter referred to as a composition) that has been put to practical use has a thickness of about 20 μm obtained by a liquid quenching method.
, a quenched alloy ribbon with a width of approximately 300 μm mainly composed of rare earths, Fe, and B is coarsely crushed using a stamp mill, etc., and a thermosetting resin such as an epoxy resin or a thermoplastic resin such as a polyamide resin is added as a binder. Manufactured by Further, it is manufactured by further pulverizing the coarsely crushed magnet powder using a vibrating ball mill, a cup mill, or the like.

0004

[Problems to be Solved by the Invention] However, when a rapidly solidified alloy ribbon is coarsely crushed using a stamp mill or the like, the maximum particle size is 300 μm or more, and the average particle size is about 200 μm. Therefore, when compression molding into a magnetic shape, a high molding pressure of 5 to 10 t/cm2 is required, which can shorten the life of the mold and lead to damage. There is a problem in that the large variations in properties lead to variations in the height of the magnets, resulting in a decrease in the production rate. Further, in the method of performing secondary pulverization, there are problems in that the particles become too fine, with approximately 10% of the particles having a particle size of 35 μm or less, resulting in deterioration of magnetic properties and oxidation of the alloy powder.

[0005] In the present invention, when magnetizing by compression molding,
A rare earth-Fe-B bonded magnet composition that does not require high molding pressure, does not shorten the life of the mold or cause damage, has excellent powder feeding properties to the mold, and has excellent magnetic properties. The object of the present invention is to obtain a method for producing the same.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the above-mentioned objects, the present inventors have conducted intensive research and found that
A composition in which alloy powder for magnets with a specific particle size and thickness contains a specific amount of binder, and such a composition is crushed into a quenched alloy ribbon and then passed through a sieve with a specific number of meshes together with spheres. The present inventors have discovered that the object can be achieved by vibration-pulverizing the powder and adding a specific amount of binder, thereby completing the present invention. That is, the first embodiment of the present invention contains rare earth elements, Fe, and B as main components, has a maximum particle size of 190 to 250 μm, and has an average particle size of 120 to 15 μm.
100 parts by weight of flat magnet powder having a particle size of 0 μm, 2 to 5% by weight of particles with a particle size of 35 μm or less and a thickness of 17 to 23 μm, and 0.5 to 2 parts of an epoxy resin binder.
．． 5 parts by weight of a rare earth-Fe-B bonded magnet composition, and the second embodiment is a rare earth-Fe-B bonded magnet composition containing 5 parts by weight of Fe, which is the main component of the magnet powder of the first embodiment. A third embodiment is a rare earth-Fe-B bonded magnet composition in which Fe is substituted with at least one transition metal.
The quenched alloy ribbon mainly composed of .5 parts by weight of rare earth-Fe-B
This is a method for producing a composition for bonding.

[0007] In the composition of the present invention, as the rare earth element, Nd is mainly used, but Dy, Pr, etc. can also be used. Further, as the transition metal to partially replace Fe, at least one type of transition metal group other than Co is used. Others, Co,
Elements that improve magnetic properties, such as V, Si, and Zr, may be used as additive elements. The composition range of the composition is preferably 11 to 14 rare earth elements, 78 to 85 Fe, and 4 to 8 B (atomic %). Therefore, it is preferable to use a pulverized quenched alloy ribbon having a thickness of 17 to 23 μm and having a maximum particle size of 190 to 23 μm.
250 μm, average particle size 120-150 μm, particle size 3
2 to 5% by weight of grains of 5 μm or less and a thickness of 1
It is necessary to have a flat plate shape of 7 to 23 μm. In other words, when it contains powder with a maximum particle size of more than 250 μm or is composed of powder with an average particle size of more than 150 μm,
Powder feeding into the mold is poor, the density of the compression molded product is not uniform, and the height of the compression molded product varies and distortion occurs. In addition, if it contains powder with a maximum particle size of less than 190 μm, or has an average particle size of less than 120 μm, and contains more than 5% by weight of powder with a particle size of 35 μm or less, it will be hardened due to hardening. Deterioration of magnetic performance occurs, e.g. B-H
Since the squareness of the second quadrant of the loop deteriorates, it is limited to the above ranges. In addition, particles with a particle size of 35 μm or less,
It is necessarily contained in an amount of 2% by weight or more in the crushing process.

[0008] Furthermore, the binder uses epoxy resin, which has excellent adhesion with the alloy powder for magnets, and has the property of increasing mechanical strength by compression molding and curing the epoxy resin. 0.5 to 2.5 parts by weight is added to 100 parts by weight of alloy powder for magnets, and if it is less than 0.5 parts by weight, the mechanical strength of the compression molded product It is easy to break due to insufficient 2.5
This is because if the amount exceeds 1 part by weight, the magnetic properties deteriorate and excessive resin adheres to the mold during compression molding, making it difficult to take out the compression molded product from the mold without damaging it. To cure this epoxy resin, as is customary, a curing agent must be added, such as at least one of primary amines, secondary amines, tertiary amines, acid anhydrides, phenols, etc. 1 to 50% of one type is added. In particular, when curing using tertiary amines, high temperature and long processing conditions are required, so a curing catalyst is also used to lower the curing temperature. It is desirable to shorten the curing time.

The composition of the present invention is produced by coarsely crushing a quenched alloy ribbon, then vibrationally crushing it on a sphere and a sieve of 80 to 100 mesh, and adding an epoxy resin binder to the crushed powder. The sphere used in this case has an outer diameter of 8 to 16
mm stainless steel spheres or ceramic spheres such as alumina, or nylon spheres with an outer diameter of 12 to 25 mm, acrylonitrile-butadiene-styrene copolymer (ABS) spheres, polyethylene spheres, polypropylene spheres, etc. It is preferable to use

[0010] The degree of crushing on the sieve is determined by the opening of the sieve,
It is affected by the frequency of vibration, the amount of material to be crushed, the size, material, and quantity of the spheres, but the major influence is the opening of the sieve, and the degree of crushing can be adjusted by changing the number of meshes of the sieve. Good. In the present invention, a sieve of 80 to 100 mesh is used. This is because when the pulverized powder is mixed with an organic synthetic resin binder and press-molded with less than 80 mesh, the density of the press-molded product does not become large and the magnetic properties of the bonded magnet are insufficient, resulting in the mesh of the sieve. If the number exceeds 100 meshes, the number of fine powders increases, so the density of the compacted compact may not increase, or the fine powders will be more oxidized, resulting in a slight deterioration of the magnetic properties of the bonded magnet. It is from.

[0011] The vibration frequency is 2000 to 4000 rpv (1
(number of vibrations per minute) is desirable.

Strictly speaking, the degree of pulverization must be investigated and adjusted by measuring the particle size distribution of the pulverized powder, but rare earth-Fe-B magnet powder can be microscopically Since it is weakly magnetic, it is difficult to completely separate fine powders from each other, making accurate particle size distribution measurement impossible. Therefore, a bonded magnet is produced by mixing an organic synthetic resin binder with pulverized powder, press molding, curing, and magnetization steps, and the magnetic properties of the magnet are measured and the degree of pulverization is determined from the measured value.

[0013]

[Operation] The composition of the present invention is produced by crushing a coarsely crushed powder of a quenched alloy ribbon with a thickness of 17 to 23 μm by vibrating it with a sphere on an 80 to 100 mesh sieve, and adding a binder to the crushed powder. Therefore, the spheres will break when they give a weak impact to the quenched alloy ribbon, and they will not be crushed by frictional force as in ball milling, and if the mesh number of the sieve is appropriate. This prevents the powder from being crushed too much, resulting in too much fine powder, which immediately falls through the openings of the sieve and is collected in the container at the bottom. Furthermore, the composition of the present invention has good powder feeding properties without deteriorating its magnetic properties, which is a very important property for rare earth-Fe-B bonded magnets. This is because rare earth-Fe-B bonded magnets have good moldability and excellent magnetic performance, and are often used for small precision instruments, so the wall thickness is 0. It is manufactured as an extremely thin product with a thickness of N to Nmm. Therefore, the gap between the compression molding mold and the die and the core becomes narrow, and it is not easy to fill the gap uniformly when the composition is allowed to fall naturally into the gap.

[0014] Thus, the composition of the present invention has a small amount of large particle size powder and small particle size powder, and is composed of an alloy powder for magnets with a sharp particle size distribution and an epoxy resin binder, so that it can be compression molded. The ability to feed powder into the mold for compression molding is improved when magnetizing it, and the molding pressure during compression molding can be lower, so the life of the mold is not shortened or damaged, and , which does not cause a decrease in magnetic performance due to hardening.

[0015]

[Example] Next, an example of the present invention will be described. Example 1 1) Preparation of alloy powder for magnets A single roll liquid quencher sprays the melt onto one copper roll rotating at a circumferential speed of 20 m/sec to form a width of approximately 0.3 m.
A quenched rare earth-Fe-B alloy ribbon having a thickness of approximately 20 μm was produced, and this ribbon was coarsely crushed using a stamp mill so that the size of the ribbon was 35 mesh or less. Rare earth - Fe
-The composition of the B-based alloy quenched ribbon is, in atomic ratio, Nd12.2
%, Fe76.8%, Co5.5%, and B4.9%.

[0016] Next, 20 kg of this coarsely crushed powder was sieved to
A container containing a 00 mesh sieve with an outer diameter of 600 mm, the material to be crushed immediately above the sieve, and 300 SUS φ12 mm spheres for crushing is vibrated by a vibration generator, and the powder passing through the sieve is naturally It was charged into a device designed to discharge at a frequency of 3000 r. p. Vibrate for 10 minutes at
It was processed until there was no powder on the sieve.

Table 1 shows the conditions during this pulverization, and Table 2 shows the results of measuring the particle size distribution of the powder obtained by pulverization using a scanning electron microscope. Furthermore, a scanning electron micrograph of the obtained powder is shown in FIG.

2) Preparation of composition 15 g of powdered cresol novolak type epoxy resin was dissolved in 200 ml of methyl ethyl ketone (1st class reagent), and 1 ml of dicyandiamide (1st class reagent) was added as a curing agent.
．． 5 g and 0.03 g of 3-hydroxypyridine (first class reagent) as a curing catalyst were added and mixed.

[0019] Add the alloy powder 1 prepared in 1) to this mixed solution.
Kg was added, mixed in a mixer for 1 hour to volatilize most of the methyl ethyl ketone, and then vacuumed for 3 hours in a vacuum dryer at room temperature to completely volatilize the remaining methyl ethyl ketone to prepare a composition for a bonded magnet. did.

3) Preparation outer diameter of bonded magnet φ20mm
, 0.5K of the composition obtained in 2) was placed in a compression molding mold manufactured to have a space with an inner diameter of 18 mm and a height of 30 mm.
The composition was fed by making three reciprocating movements of a powder feeder loaded with 10 g. Further, the molded product was molded at a surface pressure of 7 t/cm 2 , and the resulting molded product was heated at 130° C. for 30 minutes to harden the epoxy resin.

[0021] Regarding the molded product after curing, the height dimension, the density measured by a micrometer, and the JIS
The angle of repose, which indicates the flowability of the composition, measured based on Z 2502 is shown in Table 3.

[0022] Next, the molded body thus obtained was
A magnetic field of 5 KOe was applied using a pulse magnetizer to create a magnet, and the residual magnetic density and maximum energy product were measured as magnetic properties using a DC self-recording magnetometer. These results are shown in Table 4. In addition, Hk listed in Table 4 is a guideline for squareness, and Br×
This is the coercive force at a value of 0.9. Example 2 The same process as in Example 1 was carried out, and the same measurements as in Example 1 were carried out, except that 300 ceramic φ15 mm spheres were used for crushing on the sieve in Example 1-1). The results obtained are shown in Tables 1 to 4. Example 3 The same process as in Example 1 was carried out, and the same measurements as in Example 1 were carried out, except that 300 nylon φ20 mm spheres were used for crushing the sieve in Example 1-1). The results obtained are shown in Tables 1 to 4. Example 4 The same process as in Example 1 was carried out, except that the spheres used for crushing on the sieve in Example 1-1) were SUS φ8 mm spheres and the crushing time was 15 minutes, and the same measurements as in Example 1 were carried out. I did it. The results obtained are shown in Tables 1 to 4. Example 5 The number of meshes of the sieve used in Example 1-1) was 80.
The process was carried out in the same manner as in Example 1, except that a mesh was used and the grinding time on the sieve was changed to 7 minutes, and various measurements were performed in the same manner as in Example 1. The results obtained are shown in Tables 1 to 4. Comparative Example 1 The same treatment as in Example 1 was carried out, and the same measurements as in Example 1 were carried out, except that the sieve used in Example 1-1) was a 60 mesh sieve and the crushing time was 4 minutes. The results obtained are shown in Tables 1 to 4. Comparative Example 2 The same treatment as in Example 1 was carried out, except that the sieve used in Example 1-1) was 150 mesh and the grinding time was 20 minutes, and the same measurements as in Example 1 were performed. The results obtained are shown in Tables 1 to 4. Comparative Example 3 A quenched alloy ribbon was prepared in the same manner as in Example 1-1), the coarsely crushed powder was used, and the subsequent treatments were carried out in the same manner as in Example 1. Various tests were conducted. The results obtained are shown in Tables 1 to 4. Comparative Example 4 A quenched alloy ribbon was prepared in the same manner as in Example 1-1) and coarsely crushed in the same manner, except that 5 kg of the coarsely crushed powder was crushed in ethanol using a ball mill with a capacity of 3000 ml.
The subsequent treatments were carried out in the same manner as in the examples, and the same tests as in the examples were conducted. The results obtained are shown in Tables 1 to 4. Comparative Example 5 The same treatment as in Comparative Example 4 was carried out, except that the grinding time was changed to 5 minutes, and the same tests as in Example 1 were conducted. The results obtained are shown in Tables 1 to 4. Examples 6 to 9 Using the alloy powder obtained in Example 1-1), the amount of epoxy resin when preparing a composition was 0.5% by weight (Example 6
), 1.0% by weight (Example 7), 2.0% by weight (Example 8), and 2.5% by weight (Example 9).
It was treated in the same manner as in Example 1, and the bending strength was determined using 2.5 g of the composition.
A test piece molded using a 5 x 6 x 15 mm square mold at a pressure of 6 t/m2 was fixed on a jig with a distance of 12 mm between supports, and the center was compressed with a movable plate. The load was measured using an autograph that uses a load cell, and the magnetic properties were also measured in the same manner as in Example 1. These results are shown in Table 5. Comparative Examples 6 and 7 The amount of epoxy resin used when preparing the composition was 0.
The same treatment as in Example 6 was carried out, and the same tests as in Example 6 were conducted, except that the amounts were 3% by weight (Comparative Example 6) and 3.0% by weight (Comparative Example 7). The results obtained are shown in Table 5.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

[0028] From these results, when comparing Examples 1 to 5 and Comparative Examples 1 to 5, the compositions under conditions other than claims 1 and 2 had a large angle of repose, and when this composition was compression molded, In this case, the height of the molded product is high and the density is low, and it was found that such powder has poor powder feeding properties to the mold. It can be seen that the magnetic performance is poor due to the low product or poor squareness. Furthermore, by comparing Examples 6 to 9 and Comparative Examples 6 and 7, it was found that compositions with an epoxy resin binder amount outside the range of 0.5 to 2.5 parts by weight had low bending strength or were magnetized. Sometimes the magnetic properties are found to be poor. Furthermore, in a manufacturing method with conditions other than claim 3, claims 1 and 2
It can be seen that the composition cannot be obtained.

[0029]

Effects of the Invention The present invention is a composition containing magnetic alloy powder in a specific particle size range and a specific thickness range and a specific amount of binder. This manufacturing method involves vibratory crushing together with spheres on a sieve with a specific mesh number, and adding a specific amount of binder, which provides excellent powder feeding into the mold during compression molding. Remarkable effects have been recognized, such as improved dimensional accuracy of the magnet, lower molding pressure, and superior productivity.

[Brief explanation of the drawing]

[Figure 1] A photograph (x140) showing the particle structure taken by a scanning electron microscope showing an example of the state of the alloy powder in the present invention.
It is.

Claims (3)

[Claims] Claim 1: The main components are rare earth elements, Fe, and B, and the maximum particle size is 190 to 250 μm, and the average particle size is 120 to 15 μm.
100 parts by weight of flat magnet powder having a particle size of 0 μm, 2 to 5% by weight of particles with a particle size of 35 μm or less and a thickness of 17 to 23 μm, and 0.5 to 2 parts of an epoxy resin binder.
．． A rare earth characterized by containing 5 parts by weight of
Composition for Fe-B bonded magnets. [Claim 2] The main component is rare earth, Fe and B partially substituted with at least one transition metal other than Fe, and has a maximum particle size of 190 to 250 μm and an average particle size of 120 μm.
250 μm and 2 to 5 weight % of particles with a particle size of 35 μm or less, and 100 parts by weight of a flat magnet powder having a thickness of 17 to 23 μm and 0.0 parts by weight of an epoxy resin binder.
5 to 2.5 parts by weight of a rare earth-Fe-B bonded magnet composition. [Claim 3] Rare earth produced by liquid quenching, F
A quenched alloy ribbon containing E and B as main components is coarsely crushed, and then the coarsely crushed powder is crushed together with spheres by vibrating on a sieve of 80 to 100 mesh, and 100 parts by weight of the crushed powder is mixed with 0.00 parts by weight of an epoxy resin binder. A method for producing a rare earth-Fe-B bonded magnet composition, which comprises adding 5 to 2.5 parts by weight.