JP2008010460A - Bonded magnet composition, bonded magnet using the same, and manufacturing method thereof - Google Patents

Abstract

[PROBLEMS] To provide good anisotropy even at a practically low orientation magnetic field strength, to have sufficient flexibility in a low-temperature environment than before, to have high mechanical strength, high residual magnetic flux density (Br) and high Provided are a composition for a bonded magnet having a maximum energy product ((BH) max), a bonded magnet, and a method for producing the same.
An anisotropic magnetic powder (A) is composed of an anisotropic magnetic powder (A) and a resin binder (B), and the anisotropic magnetic powder (A) destroys a domain wall of each magnetic particle constituting the powder. After being magnetized with a sufficiently high magnetic field (α), the magnetic particles constituting the powder are subsequently applied with a magnetic field (β) that is sufficiently high to be sufficiently kneaded with the resin binder (B). On the other hand, the resin binder (B) is provided by a composition for a bonded magnet containing a polymerized fatty acid-based polyamide block copolymer and / or a polymerized fatty acid-based polyetheresteramide block copolymer. .
[Selection figure] None

Description

  The present invention relates to a composition for a bonded magnet, a bonded magnet using the same, and a method for producing the same, and more specifically, the orientation is greatly improved with a practically low orientation magnetic field strength, and sufficient flexibility in a low-temperature environment. The present invention relates to a bonded magnet composition that can be improved in mechanical strength and a bonded magnet formed by molding the composition, and a method for producing the same.

  Bonded magnets are permanent magnets manufactured by injection molding, extrusion molding, compression molding, rolling molding, etc. by heating a composition in which magnetic powder is mixed and dispersed in a resin binder to a molten state. Has been used in various fields. For magnetic powder, ferrite magnet powder, rare earth magnet material powder such as Sm—Co, Nd—Fe—B, and Sm—Fe—N, and metal magnet material such as alnico and iron chrome cobalt are used. Yes.

Bonded magnets are molded with a composition for bonded magnets in which magnetic powder is mixed and dispersed in a resin binder, so they have excellent shape flexibility and mechanical strength, and can be integrally molded with other parts. .
Products using these bonded magnets are exposed to high temperatures of 100 ° C or higher depending on their use, and conversely, they are exposed to low temperatures of -35 ° C or lower. Since they may be exposed alternately, a heat cycle test and a heat shock test are performed in order to evaluate the use stability of the bond magnet under such a large temperature difference. When the above test is performed on a product in which a bonded magnet is integrally molded with other parts (mainly yoke material) or a product that is bonded together, the bonded magnet may be damaged due to distortion caused by the difference in thermal expansion coefficient or deterioration of the resin binder. May crack or peel from other parts, which has been a problem.

  Copolymer polyamides such as nylon 6, nylon 12, or nylon 6-12 are mainly used as the resin binder to be mixed with the magnetic powder. In order to solve the above problem, generally diisononyl adipate, A method of adding a plasticizer such as dibutyl sebacate, N-butylbenzenesulfonamide and ε-caprolactam has been used. However, even in this method, there is a problem that the flexibility at low temperature is not sufficient and the flexibility is lowered due to deterioration with time.

In addition, it improves the melt fluidity of the composition for bonded magnets and maintains good melt fluidity even if the amount of magnetic powder is increased in order to increase the magnetic force of the molded product. Proposed composition for bonded magnets containing polymerized fatty acid-based polyether ester amide block copolymer in the main resin consisting of thermoplastic resin as a resin binder for the purpose of suppressing deterioration of molding processability (For example, Patent Document 1). A bond magnet composition in which a polymer fatty acid-based polyamide block copolymer is contained in a main resin made of a thermoplastic resin has been proposed (for example, Patent Document 2).
These are all made of a thermoplastic resin as a main material resin, and a small amount of polymerized fatty acid-based polyetheresteramide block copolymer or polymerized fatty acid-based polyamide block copolymer is added to and mixed with these resin binders. Then, the problem regarding the use stability of the bonded magnet under the temperature environment could not be solved.

On the other hand, with the recent expansion of small hard disks and expansion of DVDs, the demand for further downsizing of small motors and higher performance has become very strong. Improvement of the performance of rare earth resin-bonded magnets is eagerly desired as an element that supports the high performance of this small motor.
A candidate for satisfying the demand for miniaturization and high performance of magnet application products such as small motors is a magnetic anisotropic resin-bonded magnet in which rare earth magnetic powder having magnetic anisotropy is blended with an Nd-based intermetallic compound. However, in order to obtain a magnetic anisotropic bonded magnet with higher performance using this magnetic powder, it is necessary to orient the magnetic powder by applying a large magnetic field during molding. In order to sufficiently orient the magnetic anisotropic magnet powder, for example, a very strong applied magnetic field strength (orientation magnetic field strength) of 2400 to 4000 kA / m is required. However, the magnet actually used is required to have a complicated shape in addition to the ring shape, and the ring shape is also downsized with an outer diameter of 10 mm or less. In such an environment, the orientation magnetic field is ensured. This is accompanied by difficulties in industrial production.

  With respect to these problems, in Patent Documents 3 and 4, before the magnetic powder is kneaded with the resin component, the magnetic powder is preliminarily magnetized in a magnetic field higher than the forming magnetic field and the coercive force at the magnetic powder stage. Compared to the above, it is possible to provide a resin-bonded magnet having a practical orientation magnetic field strength and excellent orientation. However, since the method is only magnetization, the following manufacturing problems occur. That is, when magnetized, each magnet powder becomes a magnet, so that the powders adhere to each other to form a large lump and increase in bulk. As a result, it becomes difficult to put the magnet powder into the kneader used for mixing with the resin because it is a lump. When the material of the kneader is a magnetic material such as iron, the magnet powder adheres to the kneader and the kneading itself cannot be performed.

Under such circumstances, a resin-bonded magnet composition that can be molded at a practical orientation magnetic field strength of about 240 to 1200 kA / m, is easy to handle, and has high orientation characteristics. The advent of a composition for bonded magnets that is excellent in flexibility, does not peel off from cracks and yoke materials during heat cycle tests and heat shock tests, and has good magnetic properties has been desired.
JP 2001-123067 A (Claims) JP 2001-240740 A (Claims) JP-A-2-251111 JP-A-6-244047

  In view of the above circumstances, the object of the present invention is to have sufficient flexibility in a low temperature environment, and to impart good anisotropy even with a practically low orientation magnetic field strength, and a higher residual magnetic flux density (Br) than before. ) And a high maximum energy product ((BH) max), an excellent mechanical strength, a composition for a bonded magnet that is compatible with small shapes, a bonded magnet using the same, and a method for producing the same It is in

  As a result of intensive studies to achieve the above object, the present inventors have formulated a resin-bonded magnet composition by blending a magnetic powder having a high anisotropic magnetic field and a thermoplastic resin binder. As the magnetic powder, a material that has been previously magnetized in a magnetic field higher than the molding magnetic field and then demagnetized so that it can be sufficiently kneaded with the resin binder is used. By using a polyamide resin containing a polyether ester amide block copolymer and / or a polymerized fatty acid-based polyamide block copolymer, good anisotropy can be imparted even at a practical low orientation magnetic field strength. Has a high residual magnetic flux density (Br) and a high maximum energy product ((BH) max), while being flexible in a low temperature environment. To improve and moldability decreases, dimensional accuracy decreases, found that a bonded magnet without causing problems such as mechanical strength reduction can be stably produced, and have completed the present invention.

  That is, according to the first invention of the present invention, in the bonded magnet composition comprising the magnetic powder (A) having anisotropy and the resin binder (B), the magnetic powder (A) having anisotropy Is magnetized with a magnetic field (α) high enough to destroy the domain wall of each magnetic particle constituting the powder, and then each magnetic particle constituting the powder is combined with the resin binder (B). The resin binder (B) is demagnetized with a magnetic field (β) that is high enough to be sufficiently kneaded. On the other hand, the resin binder (B) is a polymerized fatty acid-based polyamide block copolymer and / or polymerized fatty acid-based polyether ester amide. There is provided a composition for a bonded magnet comprising a block copolymer.

According to the second invention of the present invention, in the first invention, the magnetic powder (A) having anisotropy contains a rare earth (Nd or Sm) and a transition metal (Fe and / or Co). The composition for bonded magnets is provided.
According to the third invention of the present invention, in the first invention, the magnetic powder (A) having anisotropy has an anisotropic magnetic field of 4000 kA / m or more, and the particle size in the total magnetic powder. The composition for bonded magnets is characterized by containing 30% by weight or more of those having a thickness of 100 μm or less.
According to the fourth aspect of the present invention, in the first aspect, the magnetic powder (A) having anisotropy is a metal compound, an inorganic phosphoric acid, an inorganic phosphoric acid compound, a silane-based material having a melting point of 150 to 500 ° C. There is provided a composition for a bonded magnet, the surface of which is coated with one or more substances selected from a coupling agent or a titanium-based coupling agent.

According to a fifth aspect of the present invention, there is provided the bonded magnet composition according to the first aspect, wherein the magnetic fields (α) and (β) are each independently 1600 kA / m or more. Is provided.
According to a sixth aspect of the present invention, in the first aspect, the magnetic field (α) is 1600 kA / m or more, while the magnetic field (β) is 1800 kA / m or more. The composition for bonded magnets is provided.

According to a seventh invention of the present invention, in the first invention, the polymerized fatty acid-based polyamide block copolymer is a bonded magnet composition characterized by being represented by the following general formula (1): Provided. In _formula, R 1, _{R 3} are identical or different aliphatic diamines, and / or diamine residue selected from alicyclic diamines having a carbon number of 6-44, _{R 2} is of 6 to 22 carbon atoms A dicarboxylic acid residue selected from one or more of aliphatic or aromatic dicarboxylic acids, R ₄ represents a polymerized fatty acid residue selected from a polymerized fatty acid mainly composed of a dimer acid having 20 to 48 carbon atoms and a derivative thereof. , M is an integer from 1 to 70, and n is an integer from 1 to 150.

General formula (1)

According to the eighth invention of the present invention, in the first invention, the polymerized fatty acid-based polyetheresteramide block copolymer is a polymerized fatty acid-based polyamide skeleton (a) represented by the following general formula (1): And a polyether ester amide skeleton (b) represented by the general formula (2). In formula (1), R _{1 to} R ₄ , m, and n are the same as described above. In formula (2), R ₅ is a polyoxyalkylene glycol or dihydroxy hydrocarbon residue having 4 to 60 carbon atoms, and R ₆ is one or more aliphatic or aromatic dicarboxylic acids having 6 to 22 carbon atoms. Represents a polymerized fatty acid residue selected from one or more of a dicarboxylic acid residue selected from the above and / or a polymerized fatty acid mainly composed of a dimer acid having 20 to 48 carbon atoms and a derivative thereof, and q is an integer of 1 to 20 .

General formula (1)

General formula (2)

  According to the ninth invention of the present invention, in the first or eighth invention, the polymerized fatty acid-based polyetheresteramide block copolymer comprises a polymerized fatty acid-based polyamide skeleton (a) and a polyetherester skeleton (b). The composition for bonded magnets is characterized in that the copolymerization ratio (a) :( b) is 10:90 to 90:10.

According to a tenth aspect of the present invention, in the bonded magnet according to the first aspect, the resin binder (B) has a tensile yield stress of 18 MPa or less and a tensile fracture stress of 50 MPa or less. A composition is provided.
According to the eleventh aspect of the present invention, in the first aspect, the polymerized fatty acid-based polyamide block copolymer or the polymerized fatty acid-based polyetheresteramide block copolymer has a number average molecular weight of 1,000 to 50. The composition for bonded magnets is provided.
According to the twelfth aspect of the present invention, in the first aspect, the resin binder (B) is a polymerized fatty acid-based polyamide block copolymer and / or polymerized fatty acid-based polyetheresteramide block copolymer. The composition for bonded magnets characterized by containing 50 wt% or more is provided.
Furthermore, according to a thirteenth aspect of the present invention, in the first aspect, the resin binder (B) is 1 to 20 parts by weight based on 100 parts by weight of the composition. Item 2. A bonded magnet composition according to Item 1, is provided.

According to a fourteenth aspect of the present invention, there is provided a bonded magnet which is formed by any one of injection molding, compression molding or extrusion molding in the orientation magnetic field according to any one of the first to thirteenth aspects. A manufacturing method is provided.
According to the fifteenth aspect of the present invention, there is provided the method for producing a bonded magnet according to the fourteenth aspect, wherein the orientation magnetic field strength is 240 to 1200 kA / m.

On the other hand, according to the sixteenth invention of the present invention, there is provided a bonded magnet obtained by the fourteenth or fifteenth invention, wherein the degree of orientation is 95% or more.
On the other hand, according to the seventeenth aspect of the present invention, there is provided a bonded magnet according to the sixteenth aspect, characterized in that the elongation at break at -35 ° C. (tensile test defined in ASTM D638) is 1% or more. Provided.

According to the composition for a bonded magnet of the present invention, a rare earth-transition metal magnetic powder that has been demagnetized after being previously magnetized under specific conditions as a magnetic powder, and a specific polymer fatty acid type as a resin binder is used. Since a polyetheresteramide block copolymer and / or a polymerized fatty acid-based polyamide block copolymer is used, the bonded magnet formed from this composition has good anisotropy even with a practical low orientation magnetic field strength. Can be granted. In addition, it has a higher residual magnetic flux density (Br) and a higher maximum energy product ((BH) max) than before, and has good flexibility even when exposed to a low temperature environment of about -35 ° C. Detachment from cracks and yoke material during heat cycle test and heat shock test is improved.
In addition, by uniformly coating the surface of the iron-based magnetic powder containing rare earth elements with a specific film such as a phosphate, a composition for a bond magnet having better weather resistance can be obtained. Furthermore, the bonded magnet obtained by molding this can be used in a wide range of fields including general home appliances, communication / acoustic equipment, medical equipment, and general industrial equipment, and its industrial value is extremely large.

  Hereinafter, the composition for bonded magnets, the bonded magnet, and the production method thereof of the present invention will be described in more detail.

  The bonded magnet composition of the present invention is a bonded magnet composition comprising an anisotropic magnetic powder (A) and a resin binder (B). After magnetizing with a magnetic field (α) high enough to destroy the domain wall of each magnetic particle constituting the powder, each magnetic particle constituting the powder is then sufficiently kneaded with the resin binder (B). The resin binder (B) is demagnetized with a magnetic field (β) as high as possible, while the polymerized fatty acid-based polyamide block copolymer and / or polymerized fatty acid-based polyetheresteramide block copolymer It is characterized by containing a coalescence.

1. Magnetic powder An anisotropic rare earth-transition metal magnetic material powder containing a rare earth element and a transition metal element is used as the magnetic powder (A).

As the rare earth elements, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy) , Holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), while transition metal elements include iron (Fe), cobalt (Co), nickel ( Ni) and manganese (Mn) are listed, and one or more of each is selected from each of these groups.
In addition to this, in transition metal element, you may contain either Cr, V, or Cu. A particularly preferred rare earth element is either Nd or Sm, and a transition metal element is either Fe or Co.

Examples of the rare earth-transition metal magnetic powder include rare earth-cobalt, rare earth-iron-boron, rare earth-iron-nitrogen magnetic powder, and the like. Among these, in particular, Sm or Nd is 5 to 40 at. %, Fe and / or Co 50-90 at. % Content is preferred.
The physical properties of the rare earth-transition metal based magnetic powder are not particularly limited, but must be anisotropic and preferably have a magnetism of 4000 kA / m or more. Each magnetic particle constituting the powder preferably contains 30% by weight or more of particles having a particle size of 100 μm or less. From the viewpoint of the melt fluidity of the obtained bonded magnet composition, the orientation of the magnetic powder, the filling rate, etc., the average particle size is usually preferably from 0.1 to 100 μm, and more preferably from 0.1 to 10 μm.

In the present invention, the surface of the rare earth-transition metal magnetic powder is coated with at least one selected from inorganic phosphoric acid, inorganic phosphoric acid compound, silane coupling agent, and titanium coupling agent by a method described in detail later. It is desirable to form a film with a substance.
Depending on the required magnetic properties, one or more of magnetic powders of ferrite powders such as Sr ferrite and Ba ferrite and metal magnetic material powders such as alnico, iron, chromium and cobalt are mixed with rare earth-transition metal magnetic material powders. Can be used.

2. Magnetization and demagnetization of magnetic powder The magnetic powder used in the present invention has anisotropy, and a magnetic field (α that is high enough to destroy the domain wall of each magnetic particle constituting the powder) ) And then demagnetized with a magnetic field (β) high enough to allow the magnetic particles constituting the powder to be sufficiently kneaded with the polyamide resin (B) of the resin binder. I must. The magnetic fields (α) and (β) are desirably 1600 kA / m or more independently of each other.

  Examples of anisotropic magnetic powder include Sm—Fe—N alloy fine powder obtained by nitriding and finely pulverizing SmFe alloy coarse powder obtained by the reduction diffusion method. The average particle size of such anisotropic magnetic powder affects the improvement of the mechanical strength and workability of the rare earth bonded magnet after molding, and the uniformity of the surface magnetic flux of the magnet after processing. Usually, the thickness is set to 2 μm to 4 μm. However, the magnetic powder is an aggregate in which magnetic particles are partitioned by domain walls, and the magnetic directions of the magnetic particles constituting the magnetic powder are in an uneven state. Magnetization is to align the magnetic direction in one direction. For this reason, magnetization is performed with a magnetic field (α) high enough to destroy the domain walls of the magnetic particles constituting the powder.

  The magnetic field (α), that is, the magnetizing magnetic field is 1600 kA / m or more, preferably 1800 kA / m or more. If it is less than 1600 kA / m, the magnetic powder having a coercive force close to this cannot be oriented, and high orientation characteristics cannot be obtained.

  The magnetizing power source for magnetizing the magnetic powder is selected in consideration of factors such as the type of magnetic powder, the number of magnetic poles, and the size. In order to magnetize the magnetic powder, a very large amount of energy is required. As shown in FIG. 1, a high magnetic field charged to the capacitor from the power source 2 is passed through the jig 3 at once to give a high magnetic field to the magnetic powder 1. become. Usually, there are two types of capacitors used in the magnetized power supply: oil capacitors and chemical capacitors. Generally, when a voltage of 1000 V or higher is required, an oil capacitor is employed. In order to obtain the required magnetization characteristics, a jig 3 (container) that contains the magnetic powder 1 to be magnetized is used. The jig is not particularly limited as long as it is made of a nonmagnetic material and has a sufficient space for the magnetic powder to move during orientation. For example, in a cylindrical container made of polyethylene, a height (L) that can accommodate at least three times the bulk density of the magnetic powder (the thickness l of the packed layer) should be in the magnetization direction.

  As a result, it is possible to obtain a resin-bonded magnet having a practical orientation magnetic field strength and excellent orientation as compared with an unmagnetized product. However, in the state where only the magnetization is performed, each magnet powder becomes a magnet, and the powders are attracted to each other to form a large lump, which increases the bulk. As a result, since it is mixed with the resin, it is difficult to put the magnet powder into the kneader. When the material of the kneader is a magnetic material such as iron, the magnet powder adheres to the kneader and the kneading itself cannot be performed. Therefore, it is necessary to subsequently demagnetize the magnetic particles constituting the powder with a magnetic field (β) that is high enough to be sufficiently kneaded with the polyamide resin (B) of the resin binder.

  The magnetic field (β), that is, the demagnetizing magnetic field is 1600 kA / m or more, more preferably 1800 kA / m or more, and more preferably 2000 kA / m or more. If it is less than 1600 kA / m, the magnetic powder having a coercive force close to this cannot be demagnetized and remains in a large lump while the powders are attracted to each other, and the magnet to the kneader used for mixing with the resin It becomes difficult to put the powder because it is a lump. When the material of the kneader is a magnetic material such as iron, the magnet powder adheres to the kneader and the kneading itself cannot be performed.

Anisotropic magnetic powder has a very high coercive force (HC) compared to a general magnetic material and does not easily demagnetize. In order to demagnetize this, a method of resonance attenuation demagnetization using a capacitor and a coil is employed. For this reason, in the demagnetizing power source, the high electric charge charged in the capacitor is caused to flow through the coil in the same manner as the magnetizing power source to generate a resonant magnetic field. In the coil, since the NS pole is attenuated while being inverted, the magnetic powder is demagnetized in the inverted magnetic field.
In the present invention, the magnetizing and demagnetizing device is not particularly limited as long as it has a power source capable of applying an applied magnetic field for magnetizing and demagnetizing. Commercially available oil capacitor type magnetizing / demagnetizing power sources include, for example, CM-1500V, 2500V, 4000V type manufactured by Denki Magnetic Industry Co., Ltd. In addition, a device having a function of switching capacitor capacity, a function of switching flywheel diode input, or the like may be used.
If the magnetic powder is SmFeN-based, it can be demagnetized relatively easily. For a material that is SmCo-based or has an anisotropic magnetic field higher than that, the demagnetization conditions must be stricter than those of the SmFeN-based material. In addition, when the Nd system is demagnetized, the initial magnetization characteristics differ, so care must be taken.

By the way, demagnetizing means have often been employed in the field of magnet production. One is to make recycling more efficient. When a bonded magnet is injection-molded with a resin composition as a raw material, a cured resin is by-produced in a path from an injection nozzle to a mold called a sprue runner. In order to reuse this, the cured resin is finely pulverized. At this time, if magnetism remains in the cured resin product, it is entangled in a dumpling shape in the crushing process, and is attracted to the blade so that the work itself cannot be performed, so demagnetization is performed.
In addition, when the magnet is fixed to the motor housing in the magnetizing process, temporary magnetizing is performed. However, if magnetism remains when the rotor is assembled after fixing the magnet, the efficiency of the assembling process decreases. So it must be demagnetized. Furthermore, even in the case of a magnet that requires management of the magnetization amount, demagnetization is once performed before the defective product is magnetized again by the magnetization amount management.
However, even when the magnetic powder is magnetized when preparing the resin composition that is the raw material of the bond magnet, it is not demagnetized after that, and its usefulness is not studied at all. It was. The present invention intends to enable efficient kneading by performing magnetization and demagnetization when preparing a resin composition as a raw material of a bonded magnet.

  In the present invention, the structure of the magnetic powder and the mechanism of the detachable magnetism can be considered as follows. After magnetizing the anisotropic magnetic powder under the above conditions and aligning its magnetic direction in one direction, followed by demagnetization to such an extent that the residual magnetic flux density does not become zero, In some cases, the residual magnetic flux density will be close to 0T, but if the entire powder is viewed, it will remain a little less than 0.001T (10G). Thereafter, when an orientation magnetic field is applied in order to produce a resin-bonded magnet, the residual magnetism is slightly oriented and the residual magnetism is increased by increasing the residual magnetization. Then, this helps the orientation of the magnetic powder present in the vicinity, and increases the residual magnetic flux density of the magnetic powder whose residual bundle density is close to approximately 0T (0G). It can be said that such a phenomenon is that the orientation magnetic field is emitted from another part. As a result, high magnetic properties (high altitude) can be obtained with an orientation magnetic field lower than usual. That is, it can be considered that the magnetic powder that has been demagnetized functions as an alignment promotion aid.

3. Resin binder The resin binder (B) used in the present invention is a polymerized fatty acid-based polyamide block copolymer (B-1) represented by the general formula (1), or of this block copolymer (B-1). It contains any one of a polymerized fatty acid-based polyether ester amide block copolymer (B-2) obtained by copolymerizing a polyether ester represented by the general formula (2) with an oligomer.

That is, the polymerized fatty acid-based polyamide block copolymer (B-1) is represented by the general formula (1). In _formula, R 1, _{R 3} are identical or different aliphatic diamines, and / or diamine residue selected from alicyclic diamines having a carbon number of 6-44, _{R 2} is of 6 to 22 carbon atoms A dicarboxylic acid residue selected from one or more of aliphatic or aromatic dicarboxylic acids, R ₄ represents a polymerized fatty acid residue selected from a polymerized fatty acid mainly composed of a dimer acid having 20 to 48 carbon atoms and a derivative thereof. , M is an integer from 1 to 70, and n is an integer from 1 to 150.
General formula (1)

The polymerized fatty acid-based polyetheresteramide block copolymer (B-2) is a polymerized fatty acid-based polyamide block copolymer represented by the general formula (1) (wherein R _{1 to} R ₄ , m, n is the same as described above) and a polyether ester represented by the following general formula (2) is copolymerized.

General formula (2)

In the formula, R ₅ is a polyoxyalkylene glycol or dihydroxy hydrocarbon residue having 4 to 60 carbon atoms, and R ₆ is selected from one or more of aliphatic or aromatic dicarboxylic acids having 6 to 22 carbon atoms. A polymerized fatty acid residue selected from a dicarboxylic acid residue and / or a polymerized fatty acid mainly composed of a dimer acid having 20 to 48 carbon atoms and one or more of these derivatives, q is an integer of 1 to 20.

The polymerized fatty acid-based polyamide block copolymer or the polymerized fatty acid-based polyetheresteramide block copolymer preferably has a number average molecular weight of 1,000 to 50,000, more preferably 5,000 to 25,000. Preferably, 5,000 to 12,000 are most preferable. When the number average molecular weight is less than 1,000, the melt viscosity is remarkably reduced, and it may be separated from the magnetic powder during the molding process, and the strength of the bond magnet formed with the composition may be significantly reduced. When 50,000 exceeds 50,000, sufficient melt fluidity cannot be obtained during molding.
Polymerized fatty acid-based polyamide block copolymer and polymerized fatty acid polyetheresteramide block copolymer are selected in consideration of the type of magnetic powder used, the melt fluidity of the resulting bonded magnet composition, the orientation of the magnetic powder, etc. It ’s fine.

  The polymerized fatty acid-based polyamide block copolymer is a resin composed only of a polymerized fatty acid-based polyamide skeleton, and among those skeletons, a hard skeleton of a dicarboxylic acid having an aromatic ring or a short hydrocarbon chain, and a polymerized fatty acid A resin in which a soft skeleton is block-polymerized is preferable, and may be appropriately selected in consideration of the type of magnetic powder used, the melt fluidity of the obtained bonded magnet composition, the orientation of the magnetic powder, and the like.

  The polymerized fatty acid-based polyether ester amide block copolymer (B-2) is a copolymerization ratio (a) between the hard skeleton (a) of the polymerized fatty acid-based polyamide and the soft skeleton (b) of the polyether ester: It is desirable to select a resin having (b) of 10:90 to 90:10. The copolymerization ratio (a) :( b) is preferably 30:70 to 70:30.

  Also, polymer fatty acid-based polyamide block copolymers (B-1) having different grades or polymerized fatty acid-based polyetheresteramide block copolymers (B-2) having different grades may be mixed. Good. Furthermore, it is also possible to mix and use the polymerized fatty acid polyamide block copolymer (B-1) and the polymerized fatty acid polyetheresteramide block copolymer (B-2). The mixing ratio is arbitrary, but (B-1) :( B-2) is preferably 20:80 to 50:50.

  The polymerized fatty acid-based polyamide block copolymer (B-1) and polymerized fatty acid-based polyetheresteramide block copolymer (B-2) used in the present invention are disclosed in JP-A-5-320335 and JP-A-5-320336. It can be produced by a method described in detail in the publication.

  The polymerized fatty acid-based polyamide block copolymer (B-1) is produced by mixing a specific polymerized fatty acid (I), dicarboxylic acid (B), and diamine (C) and polycondensing them.

  As the polymerized fatty acid (a), a polymerized fatty acid obtained by polymerizing an unsaturated fatty acid having 20 to 48 carbon atoms, for example, a monobasic fatty acid having one or more double bonds or triple bonds having 10 to 24 carbon atoms is used. Used. Specific examples include natural animal and vegetable oil fatty acids such as soybean oil fatty acid, tall oil fatty acid, and rapeseed oil fatty acid, polymerized fatty acids obtained by purifying these from oleic acid, linoleic acid, erucic acid, and the like, and ester derivatives thereof.

  Commercially available polymerized fatty acids usually contain dimer acid (dimerized fatty acid) as the main component, but also contain fatty acids as raw materials and fatty acids higher than trimer, but dimer acid (dimerized fatty acid). It is desirable that the content is 70% or more, preferably 95% or more, and the degree of unsaturation is reduced by hydrogenation. In particular, commercially available products such as pre-poles 1004 and 1009, pre-pole 1010 (manufactured by Unikema) and Empor 1008 (manufactured by Cognis) are preferred. Of course, mixtures and ester derivatives thereof can also be used.

As the dicarboxylic acid (b) used together with the polymerized fatty acid, aliphatic or aromatic dicarboxylic acids having 6 to 22 carbon atoms and ester derivatives thereof are used. For example, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexadecanedioic acid, eicosandioic acid, eicosadiene dienedioic acid, diglycolic acid, 2,2,4-trimethyladipic acid Xylene dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, and ester derivatives thereof may be used.
In particular, azelaic acid, sebacic acid, dodecanedioic acid and a mixture thereof are preferable from the viewpoints of polymerizability, copolymerization with polymerized fatty acid, and physical properties of the obtained polyamide copolymer.

  The diamine (c) is preferably a diamine having 2 to 20 carbon atoms, and specifically includes ethylenediamine, 1,4-diaminobutane, tetramethylenediamine, methylpentamethylenediamine, hexamethylenediamine, nonamethylenediamine, unamethylene. Decamethylenediamine, dodecamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, bis- (4,4'-aminocyclohexyl) methane, metaxylylenediamine paraxylylene Examples include alicyclic diamines such as amines, isophorone diamines and norbornane diamines, and aliphatic diamines such as dimer diamines derived from polymerized fatty acids having 20 to 48 carbon atoms.

The weight of (i) with respect to (b) above (b) a polymerized fatty acid having 20 to 48 carbon atoms, (b) azelaic acid and / or sebacic acid, and (c) a diamine having 2 to 20 carbon atoms. The mixture is mixed and polycondensed so that the ratio (A) / (B) is 0.3 to 5.2 and all amino groups are substantially equivalent to all carboxyl groups. When (i) / (b) is less than 0.3, the resulting polyamide copolymer has insufficient flexibility. On the other hand, when it is greater than 5.2, it is too soft and the heat resistance is significantly reduced. The intended polyamide copolymer cannot be obtained.

  Specifically, in a reaction vessel sufficiently substituted with nitrogen, (a) polymerized fatty acid, (b) azelaic acid and / or sebacic acid, and (c) hexamethylenediamine are combined with respect to the above (b). The weight ratio (A) / (B) of (A) is 0.3 to 5.2, and all amino groups are charged to be substantially equivalent to the total carboxyl groups. By raising the temperature to 200 to 280 ° C. in the presence of a small amount of a polycondensation catalyst (phosphoric acid, etc.) and reacting for 1 to 3 hours, and further reacting under reduced pressure of about 160 mmHg for 0.5 to 2 hours. A polyamide copolymer having a high molecular weight and excellent flexibility is obtained. As the molecular weight modifier, a carboxyl group-containing hydrocarbon such as acetic acid, propionic acid, butyric acid, valeric acid, lauric acid, palmitic acid, stearic acid, and behenic acid can be used.

  On the other hand, this polymerized fatty acid-based polyetheresteramide block copolymer (B-2) is obtained by mixing and polycondensing a specific polymerized fatty acid (I), dicarboxylic acid (B), and diamine (C). Further, it is produced by reacting an oligomer of the above polymerized fatty acid-based polyamide block copolymer with polyoxyalkylene glycol or dihydroxy hydrocarbon (d).

  Polyoxyalkylene glycol (d) includes polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, block or random copolymer of ethylene oxide and propylene oxide, block or random copolymer of ethylene oxide and tetrahydrofuran. Examples include polymers and mixtures thereof.

Examples of dihydroxy hydrocarbon include ethylene glycol, propylene glycol, and the like, for example, polyolefin glycol and hydrogenated polybutadiene glycol obtained by polymerizing olefin and butadiene to hydroxylate the terminal and hydrogenating the double bond. be able to.

  The copolymerization ratio (a) :( b) between the polyether ester skeleton (a) of the polymerized fatty acid-based polyether ester amide block copolymer and the polymerized fatty acid-based polyamide skeleton (b) is 10:90 to 90:10. It is preferable to change between them according to required characteristics. In particular, (a) :( b) is preferably 80:20 to 50:50. If the polymerized fatty acid-based polyamide skeleton is less than 10, the resin may be too soft and the required molded product strength may not be obtained, and if it exceeds 90, the molded product may become brittle.

The polymerized fatty acid-based polyamide block copolymer thus produced includes “PA-30R”, “PA-30M”, “PA-30”, and “PA-40M” manufactured by Fuji Chemical Industry Co., Ltd. ”,“ PA-50R ”,“ PA-50M ”,“ PA-60 ”,“ PA-160M ”,“ PA-160 ”,“ PA-260R ”,“ PA-260M ” , “PA-260”, “PA-270M”, “PA-280R”, “PA-280M”, “PA-280”, and the like.
Examples of the polymerized fatty acid-based polyether ester amide block copolymer include “TPAE8”, “TPAE10 · C”, “TPAE10 · HP”, and “TPAE12” manufactured by Fuji Kasei Kogyo Co., Ltd.

  These polyamide copolymers can be used as long as the above conditions are satisfied. However, in the mechanical properties of the resin alone, the tensile yield stress is 18 MPa or less, preferably 17 MPa or less, and the tensile fracture stress is 50 MPa. Hereinafter, it should be preferably 45 MPa or less. Here, the stress measurement is based on JIS K7162 and evaluates a sample which is injection-molded into a normal temperature mold and dried. If the tensile yield stress exceeds 18 MPa or the tensile fracture stress exceeds 50 MPa, flexibility at low temperatures is deteriorated, which is not preferable.

  Other resin can be mix | blended with the resin binder of this invention, unless the objective of this invention is impaired. For example, nylon 6, nylon 12, nylon 6-12, 4-6 nylon and its modified nylon, polyamide resin such as nylon elastomer, polyolefin resin such as polyethylene and polypropylene, polystyrene resin, polyvinyl resin, acrylic resin Acrylonitrile resin, polyurethane resin, polyether resin, fluorine resin, polyphenylene sulfide resin, vinyl chloride resin, polycarbonate resin, polysulfone resin, vinyl acetate resin, ABS resin, acrylic resin, polyether ether ketone, etc. it can.

  These thermoplastic resins preferably have a low melt viscosity and molecular weight within a range where desired mechanical strength can be obtained. For example, in the case of 12 nylon, the molecular weight is preferably 15,000 or less. Further, the shape as a raw material is not particularly limited, such as powder, beads, pellets, etc., but in view of uniform mixing with magnetic powder, a powder shape is desirable.

Among these, polyamide resins such as 12 nylon and polyphenylene sulfide resins are preferably used because of various properties of the obtained molded product and ease of production thereof. Two or more of these thermoplastic resins can be blended and used.
However, these thermoplastic resins cannot be blended in an amount of 50 wt% or more with respect to the main resin binder. If 50 wt% or more is blended, both the elongation at break and the magnetic properties are lowered, and flexibility under a low temperature environment cannot be improved, which is not preferable.

  Patent Documents 1 and 2 describe that it is not preferable to add too much polymerized fatty acid polyamide-based resin to the entire magnet composition because the magnetic powder content is relatively reduced and the magnetic properties are lowered. However, since the polymerized fatty acid polyether ester amide block copolymer and the polymerized fatty acid-based polyamide block copolymer have good mechanical properties, if this blending amount is 50 wt% or more of the resin binder, It is possible to suppress the occurrence of stress cracking or the like of the bonded magnet resulting from the difference in thermal expansion coefficient between the bonded magnet and the yoke material.

4). Method for producing composition for bonded magnet The composition for bonded magnet of the present invention comprises: (1) the surface of magnetic powder is coated with a metal compound or phosphoric acid compound having a melting point of 150 to 500 ° C., and (2) a cup if necessary. After coating with a ring agent or lubricant, (3) magnetized and demagnetized magnetic powder under the specified conditions, and (4) mixed with the specific resin binder and dispersed magnetic powder. The

(1) Coating with metal compound or phosphoric acid compound In the present invention, the magnetic powder previously magnetized and demagnetized having the specific anisotropy with a metal compound or phosphoric acid compound having a melting point of 150 to 500 ° C in advance is used. Treat the surface.

(Metal compound)
The metal compound, such as zinc (Zn), can form a Zn-containing film after reacting or not reacting, and can coat the surface of the R-TN magnetic powder substantially uniformly. Specific examples include Zn, tin (Sn), indium (In), lead (Pb), and the like.

  The metal compound needs 0.1 to 9.1% by weight of the magnetic powder in order to protect the surface of the iron-based magnetic powder containing rare earth elements. The film is obtained by mixing magnetic powder and metal powder such as Zn, heat-treating in an inert gas at 200 to 500 ° C., covering the surface of the magnetic powder, and then crushing the magnetic powder aggregated by the heat treatment. It is done.

(Phosphoric acid compound)
As the phosphoric acid compound, it is important that the phosphoric acid compound itself forms a phosphate after the reaction or unreacted and is coated on the surface of the R-TN magnetic powder. As the surface coating material capable of satisfying these conditions, commercially available phosphoric acid, phosphoric acid solution, phosphate solution, a mixture thereof, and / or a phosphate-based surface treatment agent can be used. Phosphoric acid compounds include phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, linear polyphosphoric acid, and cyclic metaphosphoric acid. Examples of the phosphoric acid-based surface treatment agent include organic phosphoric acid compounds such as phosphoric acid-based, manganese phosphate-based, zinc phosphate-based, sodium hydrogen phosphate-based, calcium phosphate-based, and organic phosphate ester-based compounds. These phosphoric acid compounds can be used alone or in combination of two or more.
In addition, ammonium phosphate, ammonium magnesium phosphate, etc., zinc phosphates that form hopite, phosphoferrite, etc. on the surface of magnetic powder, zinc calcium phosphates that form phosphite, phosphite, etc. Examples thereof include compounds that form films such as manganese phosphates that form light, iron heuriolite, etc., iron phosphates composed of strenite, hematite, and the like. The above phosphoric acid compound is usually mixed with a chelating agent, a neutralizing agent or the like to form a treating agent.

  Among these, phosphoric acid, zinc phosphate-based, manganese phosphate-based, and iron phosphate-based compounds exhibit preferable performance because the protective layer is formed on the surface of the magnet powder containing these rare earth metals as the metal elements. It is thought that it is easy to form. These phosphoric acid compounds may be used alone or in combination.

The phosphoric acid compound is surface-treated by either a wet treatment method or a dry treatment method, and is then fixed to the magnetic powder more stably by heating and drying. That is, the surface treatment solution and the magnetic powder are sufficiently mixed and stirred (for example, 40 rpm, 20 ° C., holding / stirring time 20 minutes) by a planetary mixer, and finally 10 to 10 in a vacuum oven at 100 to 150 ° C. Let dry for 30 hours.

  Although the addition amount of a phosphoric acid compound changes with kinds and density | concentrations, it is 0.01-10 weight part with respect to 100 weight part of magnetic powder. 0.05 to 7 parts by weight, particularly 0.1 to 5 parts by weight is preferred. Thereby, a film of a phosphate compound having a thickness of about 5 to 100 nm can be formed on the magnetic powder. When the addition amount is less than 0.01 parts by weight, the film is not sufficiently formed. When the addition amount exceeds 10 parts by weight, the density of the magnetic powder is lowered, and the magnetic properties and mechanical strength are lowered.

  This coating solution is sufficiently mixed and stirred (40 rpm, 20 ° C., holding / stirring time 20 minutes) in a magnetic powder and a planetary mixer, and finally in a vacuum oven at 100 to 150 ° C. for 10 to 30 hours. Dry and coat with magnetic powder.

  Here, the thickness of the phosphate film necessary for protecting the magnetic powder surface is usually 3 to 100 nm on average. When the average thickness of the phosphate film is less than 3 nm, sufficient weather resistance cannot be obtained, and when it exceeds 100 nm, the magnetic properties are deteriorated and the kneadability and moldability are deteriorated when producing a bonded magnet. . Further, being uniformly coated means that 80% or more, preferably 85% or more, more preferably 90% or more of the surface of the magnetic powder is covered with a phosphate film.

  What is remarkably effective in the present invention is a rare earth-iron-based magnetic powder whose surface is uniformly coated with a metal compound film or an average 3-100 nm phosphate film. As proposed by the present applicant (Japanese Patent Laid-Open No. 2001-207201, Japanese Patent Laid-Open No. 2003-7521), the magnetic powder has significantly improved weather resistance as compared with the conventional powder. The composition for bonded magnets obtained by kneading this magnetic powder with conventional polyamide 6, nylon 12, or nylon 6-12, such as copolymer polyamide, has greatly improved weather resistance, Molding workability is still insufficient, and the mechanical strength of the magnet obtained by molding is slightly reduced. However, it is greatly improved by using a polymerized fatty acid-based polyetheresteramide block copolymer and / or a polymerized fatty acid-based polyamide block copolymer as the main resin binder.

  Among the rare earth-iron-based magnetic powders, 20 to 25 wt% R (rare earth element), 2.1 to 3.9 wt% N (nitrogen), 0.2 to 2.0 wt% P (phosphorus), Th2Zn17 in which 0.5 to 5.0 wt% of O (oxygen) and the balance are T (transition metal element and unavoidable impurities), and the content of H (hydrogen), which is an unavoidable impurity, is 0.3 wt% or less. When a rare earth-iron-nitrogen (RTN) type magnetic powder having a type or Th2Ni17 type crystal structure is selected, the surface properties of the molded body are good, and the melt flowability, molding processability, Mechanical strength is improved and more effective.

  Here, the rare earth element (R) is contained in an amount of 20 to 25 wt%, preferably 23 to 25 wt%. If R is less than 20 wt%, the remanent magnetization and coercive force of the magnetic powder will decrease, and if it exceeds 25 wt%, the remanent magnetization and weather resistance of the magnetic powder will decrease. N (nitrogen) is contained in an amount of 2.1 to 3.9 wt%, preferably 2.8 to 3.5 wt%. If N is less than 2.1 wt% or exceeds 3.9 wt%, the remanent magnetization and coercive force of the magnetic powder decrease, which is not preferable.

On the other hand, the content of P (phosphorus) which is a component of the phosphate film is 0.2 to 2.0 wt%, preferably 0.3 to 1.0 wt%. If P is less than 0.2 wt%, the magnetic powder is inferior in weather resistance and heat resistance, and if it exceeds 2.0 wt%, the residual magnetization is undesirably lowered. Moreover, O (oxygen) is 0.5 to 5.0 wt%, preferably 1.0 to 3.0 wt%. If O is less than 0.5 wt%, the phosphate film on the surface of the magnetic powder is not sufficiently formed, so that not only the weather resistance and heat resistance are inferior, but also because of high surface activity, there is a risk of ignition when handled in the atmosphere. . On the other hand, if the content exceeds 5.0 wt%, the residual magnetization decreases, which is not preferable.

  The balance is a transition metal element as a main component of the magnetic powder, that is, Fe or Co. Zn, Cu, Mn, and the like may be further included as a component of the phosphate film. Therefore, it can be said that the transition metal element preferably contains one or more selected from Co, Zn, Cu, or Mn in addition to Fe. Furthermore, H (hydrogen) as an optional component inevitably mixed is 0 to 0.3 wt%, preferably 0.1 wt% or less. H adversely affects the weather resistance, and if it exceeds 0.3 wt%, the weather resistance decreases and the coercive force also decreases, so it is desirable to eliminate it as much as possible.

  Moreover, it becomes R-Fe-N type magnetic powder with a coercive force at room temperature of 400 kA / m or more by setting the average particle size to 1 to 20 μm and the component composition within the above range. Here, when the average particle size is less than 1 μm, the residual magnetization of the magnetic powder decreases, and when it exceeds 20 μm, the coercive force at room temperature may be less than 400 kA / m.

(2) Coating with Coupling Agent The magnetic powder coated with a metal compound or phosphate can be further coated with a coupling agent.

(Coupling agent)
In the present invention, the magnetic powder is subjected to a surface treatment using at least one of a silane coupling agent, an aluminum coupling agent, a titanate coupling agent, and a zirconate coupling agent. Of these, silane coupling agents or titanate coupling agents are preferred. By covering the surface of the magnetic powder by this surface treatment, the melt fluidity at the time of high filling can be improved more effectively.

  Examples of the silane coupling agent include vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexylethyltrimethoxysilane), γ-glycidoxypropyltrimethoxysilane, γ- Glycidoxymethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl- γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, phenyltriethoxysilane And organosilane monomers such as diphenyldiethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane. These silane coupling agents can also be used alone or in combination.

  Examples of the aluminum coupling agent include alkoxyaluminum chelates. Specific examples include acetoalkoxyaluminum diisopropylate. These aluminum coupling agents can be used alone or in combination of two or more.

As titanate-based coupling agents, commercially available, for example, isopropyl triisostearoyl titanate, isopropyl tri (N-aminoethyl) titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, Tetraisopropyl titanate, tetrabutyl titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tri (dioctyl phosphate) titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl Dimethacrylisostearoyl titanate, tetra (2,2-di Lil-1-butyl) bis (ditridecylphosphite) titanate, isopropyl tricumylphenyl titanate, bis (dioctyl pyrophosphate) oxy acetate titanate, and the like isopropyl isostearoyl diacryl titanate. Among these, isopropyl triisostearoyl titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl phosphite) titanate, and bis (dioctylpyrophosphate) oxyacetate titanate are particularly preferable. These titanate coupling agents can be used alone or in combination.

The coupling agent is coated by either a wet processing method or a dry processing method. For example, the coupling agent is put into a mechano-fusion apparatus and subjected to a surface treatment in advance, and then a heat treatment at around 100 ° C. is also performed. This is preferable because a more stable coated magnetic powder can be obtained.
In this mechano-fusion system, the internal rotary rotor rotates at high speed, the charged magnetic powder and organic compound are consolidated on the inner wall of the rotary rotor, and further, compression, shearing, etc. are performed in the vicinity of the gap between the inner piece tip and the rotary rotor. The structure must be affected by The conditions such as the gap between the rotating rotor and the inner piece and the number of rotations are preferably those that can be freely adjusted according to the processing speed of the organic coating on the magnetic powder and the degree of deagglomeration of the secondary particles. For example, Mechanofusion AMS series manufactured by Hosokawa Micron Co., Ltd. can be used, and Mechanofusion AMS-LAB and AMS-100F manufactured by the same company are suitable.
Then, if it heat-drys, it will fix to magnetic powder more stably. That is, the coupling agent solution and the magnetic powder are sufficiently mixed and stirred (for example, 40 rpm, 20 ° C., holding / stirring time 20 minutes) by a planetary mixer, and finally 10 in a vacuum oven at 100 to 150 ° C. Allow to dry for ~ 30 hours.

  Although the addition amount of a coupling agent changes with the kind and density | concentration, generally 0.1-10 weight part is preferable with respect to 100 weight part of magnetic powder, More preferably, it is 0.1-5 weight part. If the amount is less than 0.1 parts by weight, sufficient melt fluidity improvement and environmental resistance improvement effects cannot be obtained. If the amount exceeds 10 parts by weight, the density of the molded body decreases, and the mechanical strength of the bond magnet is reduced. Deterioration and desired magnetic properties cannot be obtained.

  As the surface treatment method of the present invention, a surface treatment step using a metal compound or a phosphoric acid compound is provided in advance to coat the magnetic powder, and then, if necessary, treated with a coupling agent, and then mixed with a resin binder. Although it is preferable, you may mix a magnetic powder, a resin binder, and a coupling agent together. However, in order to obtain a more reliable surface-treated film, it is desirable that the magnetic powder is previously treated with a coupling agent and then mixed with a resin binder.

(3) Magnetic Powder Magnetization / Demagnetization Method The surface-treated magnetic powder is magnetized / demagnetized using, for example, a capacitor-type detachable magnetic power supply device. After magnetizing with a magnetic field (α) high enough to destroy the domain wall of each magnetic particle constituting the powder, each magnetic particle constituting the powder is subsequently a polyamide resin (B) as a resin binder. And must be demagnetized with a magnetic field (β) high enough to allow sufficient kneading. The magnetic fields (α) and (β) are desirably 1600 kA / m or more independently of each other.

The magnetic field (α), that is, the magnetizing magnetic field is 1600 kA / m or more, preferably 1800 kA / m or more. If it is less than 1600 kA / m, the magnetic powder having a coercive force close to this cannot be oriented, and high orientation characteristics cannot be obtained.
The magnetic field (β), that is, the demagnetizing magnetic field is 1600 kA / m or more, more preferably 1800 kA / m or more, and more preferably 2000 kA / m or more. If it is less than 1600 kA / m, the magnetic powder having a coercive force close to this cannot be demagnetized and remains in a large lump while the powders are attracted to each other, and the magnet to the kneader used for mixing with the resin It becomes difficult to put the powder because it is a lump. When the material of the kneader is a magnetic material such as iron, the magnet powder adheres to the kneader and the kneading itself cannot be performed.

(4) Dispersion of magnetic powder in resin binder Finally, the magnetic powder surface-treated by the above method is mixed and dispersed in a resin binder.

  The blending amount of the resin binder (B) is not particularly limited, and may be appropriately selected according to the molding method at a ratio of 1 to 20 parts by weight with respect to 100 parts by weight of the composition. In particular, the resin binder (B) is preferably mixed at a ratio of 1 to 15 parts by weight. When the amount of the resin binder (B) is less than 1 part by weight, the magnetic properties are insufficient, and when the amount is more than 20 parts by weight, the moldability deteriorates, which is not preferable.

Further, in the present invention, when the magnetic powder is highly filled as described above, a remarkable effect is exhibited. However, the composition for a bonded magnet of the present invention can be used even when the blending amount of the magnetic powder is less than 80 parts by weight. This is advantageous in terms of the uniform dispersibility of the magnetic powder.
When obtaining the composition for bonded magnets of the present invention, if necessary, after blending the following additives and fillers, the bonded magnet composition may be melt-kneaded. For example, a Banbury mixer, kneader, roll , Kneaders such as kneaders, single screw extruders, twin screw extruders, and the like.

(Additive)
The composition for bonded magnets of the present invention is composed of a polyamide resin containing magnetic powder, a polymerized fatty acid-based polyetheresteramide block copolymer and / or a polymerized fatty acid-based polyamide block copolymer. In addition, when a lubricant or stabilizer is used as an additive, the heat fluidity of the composition is further improved, and the moldability and magnetic properties are improved.

  Examples of the lubricant include waxes such as paraffin wax, liquid paraffin, polyethylene wax, polypropylene wax, ester wax, carnauba, and micro wax, stearic acid, 1,2-oxystearic acid, lauric acid, palmitic acid, oleic acid, and the like. Fatty acid salts such as fatty acids, calcium stearate, barium stearate, magnesium stearate, lithium stearate, zinc stearate, aluminum stearate, calcium laurate, zinc linoleate, calcium ricinoleate, zinc 2-ethylhexoate (metal soaps) ) Stearic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, palmitic acid amide, lauric acid amide, hydroxystearic acid amide, methylene bis-stearyl Fatty acid amides such as acid amide, ethylene bis stearic acid amide, ethylene bis lauric acid amide, distearyl adipic acid amide, ethylene bis oleic acid amide, dioleyl adipic acid amide, N-stearyl stearic acid amide, fatty acid such as butyl stearate Esters, alcohols such as ethylene glycol and stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyethers composed of these modified products, polysiloxanes such as dimethylpolysiloxane and silicon grease, fluorine-based oil, fluorine Examples thereof include inorganic compound powders such as fluorine compounds such as greases and fluorine-containing resin powders, silicon nitride, silicon carbide, magnesium oxide, alumina, silicon dioxide, and molybdenum disulfide.

  As stabilizers, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2 -{3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,2,3-triazaspiro [4,5] undecane-2,4- Dione, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate Poly [[6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl ) Imino] hexamethylene [[2,2,6,6-tetramethyl-4-piperidyl] imino]], 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-n-butyl In addition to hindered amine stabilizers such as bis (1,2,2,6,6-pentamethyl-4-piperidyl) malonate, phenolic, phosphite, thioether antioxidants, etc. One or more of these can be used.

  The addition amount of these additives is appropriately selected according to the type of the resin binder and the type of the magnetic powder, and is not particularly limited, but is usually 0 with respect to 100 parts by weight of the bonded magnet composition. 0.1 to 20 parts by weight, particularly 0.1 to 3 parts by weight is preferable.

(filler)
Furthermore, a filler having a large reinforcing effect such as mica, whisker, talc, carbon fiber, or glass fiber can be appropriately added to the bonded magnet composition of the present invention as long as the object of the present invention is not hindered. That is, when the magnetic properties required for the bonded magnet are relatively low and the amount of the magnetic powder is relatively small, the mechanical strength of the bonded magnet tends to be low. In such a case, the mechanical strength is compensated. It is possible to supplement the mechanical strength of the bonded magnet by adding a filler such as mica or whisker.
The type and blending amount of these fillers are not particularly limited and may be appropriately selected according to the required properties of the bond magnet.

5. Manufacture of bonded magnets By molding this bonded magnet composition by injection molding, compression molding, extrusion molding, rolling molding, transfer molding, etc., not only magnetic properties and freedom of shape, but also rust resistance properties, mechanical strength In addition, the bonded magnet of the present invention having excellent flexibility and heat resistance can be obtained. The composition for bonded magnets of the present invention is excellent in melt fluidity, and thus any one of injection molding, compression molding and extrusion molding is suitable. In injection molding where high magnetic properties and high mechanical strength are required. Most effective. In the present invention, the molding apparatus does not have to have a special structure, and may be any apparatus having a composition supply unit, a molding unit, an orientation magnetic field application unit, and a molded body take-out unit.

The supply portion is a portion that fills a mold with a composition that is a molding material. The supply unit is preferably provided with a composition supply device such as a quantitative feeder. The slurry formed by dispersing the magnetic powder in the resin in the resin-bonded magnet composition is extracted from the mixer, and the magnetic powder and the resin are supplied to the mold while maintaining the slurry state. The
Moreover, a shaping | molding part is a part which compression-molds the composition supplied to the metal mold | die with a punch. The orientation magnetic field application unit is provided with a coil or a permanent magnet for applying a magnetic field around a mold as a molding unit. An orientation magnetic field of 240 to 1200 kA / m, preferably 240 to 800 kA / m is applied to the composition charged in the mold. If the orientation magnetic field is less than 240 kA / m, the magnetic powder cannot be sufficiently oriented, and an orientation magnetic field exceeding 1200 kA / m is not practical.
The molded body take-out part is a part for taking out the molded body from the mold. The molded body may be raised by raising the lower punch to a position where the pressing surface coincides with the upper end surface of the mold, discharging the molded body from the molding space, and then moving the molded body in the lateral direction.

That is, in injection molding, the resin-bonded magnet composition is melted in an injection unit, the melted composition is supplied to a sprue part of a mold maintained at a high temperature, and filled into a cavity part through a runner part. Then, the filled resin is held for a predetermined time while being cooled, and after the resin is cured, the cured molded product is taken out from the cavity portion, whereby the magnetic anisotropic bonded magnet of the present invention can be obtained.
In the case of injection molding, the bonded magnet composition is molded under the condition that the maximum history temperature is 300 ° C. or lower, preferably 260 ° C. or lower. When the maximum history temperature exceeds 300 ° C., there is a problem in that the magnetic characteristics are deteriorated.

The bonded magnet of the present invention has a high degree of orientation obtained by heating the resin-bonded magnet composition to the melting temperature of the thermoplastic resin, molding it in a wet magnetic field and cooling it. The degree of orientation is 95% or more, preferably 96% or more, and since it has excellent magnetic properties, it can be used in many fields.
Bonded magnets are molded compositions for bonded magnets in which a magnetic binder magnetized in a magnetic field higher than the molding magnetic field is mixed and dispersed in a resin binder containing a specific polymerized fatty acid-based polyamide copolymer. As a result, it has excellent shape flexibility and mechanical strength, and can be integrally molded with other parts.
Products using these bonded magnets are exposed to a high temperature of 100 ° C or higher depending on the application, and conversely, they are exposed to a low temperature of -35 ° C or lower, and alternate between a high temperature state and a low temperature state. May be exposed to. Even if a product in which a bonded magnet is integrally molded with other parts (mainly yoke material) or a product that is bonded together is used under such a large temperature difference, distortion caused by the difference in thermal expansion coefficient, The bonded magnet does not break or peel off from other parts due to deterioration of the resin binder. For this reason, the present invention is particularly useful in a wide range of fields such as small motors, acoustic equipment, OA equipment, etc., which are free from cracks / chips and are becoming lighter and thinner.

Hereinafter, 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 without departing from the spirit of the present invention.
The composition for bonded magnets and bonded magnets were manufactured and evaluated by the following materials / components and methods.

1. Materials / Components (1) Magnetic powder / anisotropic magnetic powder: Sm—Fe—N magnetic powder (SmFeN alloy powder manufactured by Sumitomo Metal Mining Co., Ltd.), Sm: 23.5 to 24.5 wt%, N: 3 0.1 to 3.5 wt%, anisotropic magnetic field: 16.8 MA / m (210 kOe), particle size content of 100 μm or less 99 wt%
(2) Inorganic phosphoric acid or inorganic phosphoric acid compound / phosphoric acid treatment agent (trade name: phosphoric acid (reagent), manufactured by Kanto Chemical Co., Inc.)
(3) Organic silane monomer / Organic silane monomer: γ-methacryloxypropyltrimethoxysilane (trade name: Shin-Etsu Silicone KBM503)
(4) Resin binder / polymerized fatty acid-based polyether ester amide block copolymer A
Add polyoxytetramethylene glycol and azelaic acid to polyamide oligomer reacted at 190 ° C under nitrogen atmosphere using oleic acid, linoleic acid, azelaic acid, sebacic acid and hexamethylenediamine as raw materials Polymerization was carried out at 270 ° C. with stirring. Melting point: 172 ° C., crystallization temperature: 158 ° C., MI value (measured at 230 ° C., 21.2 N load) is 300 g / 10 min. A polymerized fatty acid-based polyetheresteramide block copolymer A was obtained. This had a copolymerization ratio (a) :( b) of the polyether ester amide skeleton (a) and the polyether ester skeleton (b) of 60:40, and a number average molecular weight of about 10,000. The tensile yield stress of this resin binder evaluated based on JIS K7162 was 17 MPa (yield strain 14%), and the tensile fracture stress was 40 MPa (nominal strain at break 540%).
・ Polymerized fatty acid-based polyether ester amide block copolymer B
Except for changing the blending ratio of polyoxytetramethylene glycol and azelaic acid to the polyamide oligomer, the melting point was 153 ° C., the crystallization temperature was 122 ° C., and 230 ° C. in the same manner as the polymerized fatty acid-based polyether ester amide block copolymer A. MI value measured with a load of 21.2 N 1600 g / 10 min. A polymerized fatty acid-based polyether ester amide block copolymer B was obtained. The copolymerization ratio (a) :( b) of the polyether ester amide skeleton (a) and the polyether ester skeleton (b) was 80:20, and the number average molecular weight was about 6,000. The tensile yield stress evaluated based on JIS K7162 was 11 MPa (yield strain 14%), and the tensile fracture stress was 19 MPa (nominal strain at break 486%).
・ Nylon 12
Product name: A1709P manufactured by Daicel Degussa (number average molecular weight of about 13,000), tensile yield stress 41 MPa, tensile fracture stress 49 MPa.

2. Molded product evaluation / tensile test (-35 ℃)
Tensile test stipulated in ASTM D638 using the molded specimen obtained by injection molding to the shape specified in ASTM D638 (L: 175 mm, W: 13 mm {Tear part: 19.5 mm}, T: 3 mm) It was used for. The tensile strength was 50 MPa or more, the elongation at break was 1% or more, and the elastic modulus was 12000 MPa or more.
Magnetic property evaluation Magnetic properties such as the maximum magnetic energy product of the resin-bonded magnet sample obtained under the above injection molding conditions were measured at room temperature with a thiophye self-recording magnetometer (manufactured by Toei Kogyo Co., Ltd.). The degree of orientation was determined by the SMM method, that is, {(magnetization of resin-bonded magnet after molding) / (magnetization measured by VSM at 100% magnetic powder) × magnetic powder volume ratio of resin-bonded magnet after molding. ) × 100}. An orientation degree of 95% or more was considered to be effective.
-Density was measured with a water displacement measuring device manufactured by Toyo Seiki.

(Example 1)
(1) Surface treatment with phosphoric acid or phosphoric acid compound and organosilane monomer After dissolving 0.3 parts by weight of a surface treatment phosphoric acid compound in 10 parts by weight of an alcohol-based organic solvent such as IPA with respect to 100 parts by weight of magnetic powder The processing solution and the magnetic powder are sufficiently mixed and stirred (40 rpm, 20 ° C.) in a planetary mixer and dried in a vacuum oven at −760 mmHg and 120 ° C. for 24 hours. Surface treatment was performed by adding 0.5 parts by weight of an organosilane monomer with Mechanofusion (manufactured by Hosokawa Micron Corporation) to obtain a treated magnetic powder.
(2) Magnetization / demagnetization method of magnetic powder The surface-treated magnetic powder was subjected to magnetization / demagnetization treatment using a capacitor-type detachable magnetic power supply device manufactured by Electromagnetic Industry Co., Ltd. The conditions are shown in Tables 1 and 2.
(3) Mixing and preparation of the composition A predetermined resin is added to the total amount of the magnetic powder in a predetermined ratio (each part by weight), and as a lubricant, a specified amount is added to 100 parts by weight of the magnetic powder. The mixture was sufficiently mixed and stirred in a mixer.
The mixture thus obtained was extruded at φ20 mm single extruder (L / D = 25, CR = 2.0, rotation speed = 20 rpm, 5 mmφ strand die, cylinder temperature 200-250 ° C., die temperature 230 ° C., hot cut A pellet compound of about φ5 mm × 5 mm was prepared with a pelletizer.
The obtained pellet compound was subjected to a φ10 mm × 15 mm cylinder and a 15 mm × 8 mm × 2 mm rectangular strength test resin-bonded magnet with an orientation magnetic field strength of 480 kA / in a magnetic field injection molding machine (J-20MII) manufactured by Nippon Steel. m, a molding temperature of 220 to 230 ° C., and a mold temperature of 100 to 120 ° C., and the molded products were evaluated by the methods described above. Production conditions and evaluation results are shown in Table 1.

(Examples 2 to 4)
Using the resin composition having the same composition as that of Example 1, experiments were performed by changing the magnetization / demagnetization magnetic field (Examples 2 to 3). Experiments were performed under the same conditions as in Example 2 while changing the composition (addition ratio) of the polyamide resin (Example 4). Production conditions and evaluation results are shown in Table 1.

(Comparative Examples 1-3)
An experiment was conducted in the same manner except that conventional nylon 12 was used instead of the polyamide resin used in Example 1 (Comparative Example 1). Moreover, it experimented by performing only magnetization, not performing magnetization / demagnetization (Comparative Examples 2 and 3). Table 2 shows the manufacturing conditions and the evaluation results of the obtained bonded magnet.

In Examples 1 to 4, magnetized in advance according to the present invention and then subjected to molding in a magnetic field using a demagnetized magnetic powder and a resin binder, both of which have a low orientation magnetic field strength of 480 kA / m Regardless, it exhibits a high degree of orientation, achieves good magnetic properties, has large tensile strength and elongation, and its elongation at break greatly exceeds the target of 1%.
On the other hand, in Comparative Example 1, the used nylon 12 becomes brittle at a low temperature, and both the tensile strength and the breaking elongation are reduced. In Comparative Example 2, a magnetic powder that had been preliminarily magnetized was used, but there was a large lump of magnetic powder that accompanies magnetization, and the composition could not be obtained because it could not be charged into a kneader. In Comparative Example 3, magnetic powder that was not magnetized / demagnetized was used, so the tensile strength and elongation were large and the elongation at break was much higher than 1% of the target, but the degree of orientation was not as good as that of the present invention. .

It is explanatory drawing regarding the apparatus used for the magnetization and demagnetization of a magnetic powder, and its use in this invention.

Explanation of symbols

1 Magnetic powder 2 Power supply for magnetization / demagnetization 3 Jig (container)

Claims (17)

In the composition for a bonded magnet comprising the magnetic powder (A) having anisotropy and the resin binder (B),
The magnetic powder (A) having anisotropy is magnetized with a magnetic field (α) high enough to destroy the domain wall of each magnetic particle constituting the powder, and then constitutes the powder. Each magnetic particle is demagnetized with a magnetic field (β) high enough to be sufficiently kneaded with the resin binder (B),
On the other hand, the resin binder (B) contains a polymerized fatty acid-based polyamide block copolymer and / or a polymerized fatty acid-based polyetheresteramide block copolymer.   The composition for a bonded magnet according to claim 1, wherein the magnetic powder (A) having anisotropy contains a rare earth (Nd or Sm) and a transition metal (Fe and / or Co).   The magnetic powder (A) having anisotropy has an anisotropic magnetic field of 4000 kA / m or more, and contains 30% by weight or more of all magnetic powder having a particle size of 100 µm or less. The composition for bonded magnets according to item 1.   The magnetic powder (A) having anisotropy is made of one or more substances selected from a metal compound, an inorganic phosphoric acid, an inorganic phosphoric acid compound, a silane coupling agent, or a titanium coupling agent having a melting point of 150 to 500 ° C. The composition for resin-bonded magnets according to claim 1, wherein the surface is coated.   2. The resin-bonded magnet composition according to claim 1, wherein the magnetic fields (α) and (β) are each independently 1600 kA / m or more.   The composition for a resin-bonded magnet according to claim 5, wherein the magnetic field (α) is 1600 kA / m or more, while the magnetic field (β) is 1800 kA / m or more. The composition for a bonded magnet according to claim 1, wherein the polymerized fatty acid-based polyamide block copolymer is represented by the following general formula (1).
General formula (1)

(In the _formula, R 1, _{R 3} are identical or different aliphatic diamines having a carbon number of 6-44, and / or diamine residue selected from alicyclic diamine, _{R 2} is a carbon number 6 to 22 A dicarboxylic acid residue selected from one or more of aliphatic or aromatic dicarboxylic acids, R ₄ represents a polymerized fatty acid residue selected from a polymerized fatty acid mainly composed of a dimer acid having 20 to 48 carbon atoms and a derivative thereof. And m is an integer from 1 to 70, and n is an integer from 1 to 150.) The polymerized fatty acid-based polyetheresteramide block copolymer comprises a polymerized fatty acid-based polyamide skeleton (a) represented by the following general formula (1) and a polyetheresteramide skeleton (b) represented by the general formula (2). It contains, The composition for bonded magnets of Claim 1 characterized by the above-mentioned.
General formula (1)

(In the formula, R _{1 to} R ₄ , m, and n are the same as described above.)
General formula (2)

(In the formula, R ₅ is a polyoxyalkylene glycol having 4 to 60 carbon atoms or a dihydroxy hydrocarbon residue, and R ₆ is selected from one or more aliphatic or aromatic dicarboxylic acids having 6 to 22 carbon atoms. And a polymerized fatty acid residue selected from one or more of a polymerized fatty acid mainly composed of a dicarboxylic acid residue and / or a dimer acid having 20 to 48 carbon atoms and a derivative thereof, and q is an integer of 1 to 20.)   In the polymerized fatty acid-based polyether ester amide block copolymer, the copolymerization ratio (a) :( b) of the polymerized fatty acid-based polyamide skeleton (a) and the polyether ester skeleton (b) is 10:90 to 90:10. The composition for bonded magnets according to claim 1 or 8, wherein the composition is provided.   2. The bonded magnet composition according to claim 1, wherein the resin binder (B) has a tensile yield stress of 18 MPa or less and a tensile fracture stress of 50 MPa or less.   The composition for bonded magnets according to claim 1, wherein the polymerized fatty acid-based polyamide block copolymer or the polymerized fatty acid-based polyetheresteramide block copolymer has a number average molecular weight of 1,000 to 50,000. object.   The resin binder (B) contains a polymerized fatty acid-based polyamide block copolymer and / or a polymerized fatty acid-based polyetheresteramide block copolymer in an amount of 50 wt% or more. Composition.   The composition for a bond magnet according to claim 1, wherein the amount of the resin binder (B) is 1 to 20 parts by weight with respect to 100 parts by weight of the composition.   A method for producing a bonded magnet, wherein the composition for a resin-bonded magnet according to any one of claims 1 to 13 is molded by injection molding, compression molding or extrusion molding in an oriented magnetic field.   The method for producing a bonded magnet according to claim 14, wherein the orientation magnetic field strength is 240 to 1200 kA / m.   A bonded magnet obtained by the method according to claim 14 or 15, wherein the degree of orientation is 95% or more.   The bond magnet according to claim 16, wherein the elongation at break at −35 ° C. (tensile test defined in ASTM D638) is 1% or more.

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