JP2005072564A - Composition for bonded magnet and the bonded magnet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for a bonded magnet which can avoid defective moldings due to solidification of the composition before it is filled entirely into a cavity of a mold and has good injection moldability, and a bonded magnet made by molding it. <P>SOLUTION: In a composition for the bonded magnet, in which rare-earth/transition metal base magnetic particles (A) are mixed and dispersed with a resin binder (B), the resin binder (B) is selected from among polymerized fatty acid based polyamide block copolymer (B-1), or polymerized fatty acid base polyether-ester-amide block copolymer (B-2), and its content is made equal to 50% or larger, such that if the temperature of a molten state composition for a bonded magnet is decreased, the difference ΔT between the temperature at which the increasing rate of the viscosity of the composition starts to be larger (solidification start temperature: Ts) and the temperature at which the increasing rate of the viscosity of the composition starts to be smaller (solidification finish temperature: Tf) is made equal to 20°C or higher. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a bonded magnet composition and a bonded magnet, and more particularly to a bonded magnet composition excellent in injection moldability and a bonded magnet formed by molding the same.

  Ferrite magnets, alnico magnets, rare earth magnets, and the like are incorporated and used as motors in various products including general home appliances, communication / acoustic equipment, medical equipment, and general industrial equipment. These magnets are mainly manufactured by a sintering method, but magnets manufactured by a sintering method are fragile and difficult to be thinned, so it is difficult to form a complicated shape, and shrinks by 15 to 20% during sintering. Therefore, dimensional accuracy cannot be improved, post-processing such as polishing is required, and there are significant restrictions in terms of application.

  In contrast, resin-bonded magnets (called bond magnets) are easily filled with magnetic powder using thermoplastic resins such as polyamide resins and polyphenylene sulfide resins, and thermosetting resins such as epoxy resins and phenol resins as binders. New applications are being developed. In particular, an injection-molded magnet manufactured by injection molding using a thermoplastic resin as a binder has a feature that the shape flexibility is excellent compared to other bond magnets such as a compression-molded magnet and an extrusion-molded magnet.

  An injection-molded magnet is manufactured by injecting a bonded magnet composition melted inside a cylinder of an injection molding machine into a mold. The mold is provided with a cavity having a predetermined product shape and a runner for the melted bonded magnet composition called sprue or runner. The temperature of the mold is set so that it is not higher than the melting point of the thermoplastic resin used in the composition. Therefore, the injected molten composition is rapidly cooled and solidified in the mold, and the magnet molded product. As taken out.

  Here, for example, in the case of a bonded magnet composition using a polyamide resin as a binder, the mold temperature is often set to about 80 to 110 ° C. In order to shorten the molding cycle and improve productivity, the mold temperature may be set lower to shorten the cooling time. Also, in the case where an orientation magnetic field is generated in the cavity by embedding a rare earth sintered magnet in the die, the die is prevented in order to prevent the orientation magnetic field from decreasing according to the temperature coefficient α (Br) of the rare earth sintered magnet. The temperature may be set as low as possible. For example, α (Br) of the Nd—Fe—B sintered magnet is −0.11% / K. Therefore, when the mold set temperature changes by 80 ° C., the orientation magnetic field changes by 9%. In these cases, the mold temperature may be set to less than 80 ° C, and further to 10 to 50 ° C.

  The lower the mold set temperature, the faster the melted bonded magnet composition cools as it passes through the sprue and runner, so the composition fills well before reaching the cavity or within the cavity. It becomes solidified before, and molding defects called short shots are likely to occur.

  One countermeasure is to incorporate a hot sprue or hot runner system that can be heated into the mold to avoid solidification with the sprue runner. It is difficult to incorporate a mold having a structure. Another possible method is to raise the cylinder temperature of the injection molding machine to sufficiently raise the temperature of the injected composition. However, when the magnetic powder is a rare earth magnetic powder, it is oxidized by placing it in a high temperature. There is a possibility that the magnetic powder due to the deterioration of the characteristics, and the desired magnet performance cannot be obtained. In addition, a method has been proposed in which the melt viscosity of the composition is lowered and the flow resistance is reduced, so that the sprue and the runner are quickly passed and filled. In order to realize this, a binder having a high MI (melt flow index) value is selected, a lubricant or the like is added, or the powder properties of the magnetic powder are adjusted.

  For example, a mixture of (A) a homopolymerized polyamide resin and (B) one of a copolymerized polyamide, a polyamide-based elastomer, and a polyester-based elastomer, where (B) / (A + B) is in a specific range is used as a resin binder There has been proposed a method for manufacturing a compound for a bonded magnet in which the melt viscosity of the compound is lowered by use and the solidification rate of the once melted compound is set within a specific range (see Patent Document 1).

According to this, it is expected that a bonded magnet with good orientation and excellent magnetic properties can be obtained, but even if the melt viscosity of the composition is simply lowered, the backflow is generated inside the cylinder of the injection molding machine. There was a problem that it would not be effective unless it occurs or is an expensive ultra-high speed injection molding machine.
In addition, as another problem, even when the set temperature of the mold is a normal 80 to 110 ° C., when the time for the molten bonded magnet composition to reach the product cavity from the sprue bush of the mold is long In the course of injection filling, the melt viscosity of the composition may increase and molding defects may occur.

  On the other hand, the melt fluidity of the composition for bonded magnets can be improved and good melt fluidity can be maintained even if the filling amount of magnetic powder is increased in order to increase the magnetic force of the molded product. In order to obtain a bonded magnet molded product that can suppress a decrease in molding processability due to a decrease in property, a polymer fatty acid-based polyether ester amide block copolymer is included as a resin binder in the main resin of a thermoplastic resin. A composition for a bonded magnet has been proposed (for example, Patent Document 2). In addition, a bonded magnet composition using a resin binder 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 3).

  These use a thermoplastic resin as the main material resin, and add a small amount of polymerized fatty acid-based polyether ester amide block copolymer or polymerized fatty acid-based polyamide block copolymer to the resin binder. With this resin binder, the problem relating to the improvement of the injection moldability of the bonded magnet could not be solved sufficiently.

  Further, the bond magnet may be used by being integrally formed with other parts. In the case of a cylindrical bonded magnet having a cylindrical or cylindrical back yoke such as iron or silicon steel plate disposed on the inner or outer peripheral side thereof, the bonded magnet and the back yoke are cooled in the cooling process immediately after integral molding. The bond magnet may break due to the difference in linear expansion coefficient. There is a method of preheating the back yoke to be inserted into the mold, but it is not sufficient, and it has been difficult to cope with the conventional composition. Depending on the application of the bond magnet, the integrally molded magnet may be subjected to a heat cycle test, and even if it is not broken in the cooling process after molding, it will break depending on the heat cycle test conditions.

  Under such circumstances, the advent of a bonded magnet composition that can be satisfactorily molded without maintaining the mold and without requiring an expensive ultra-high-speed injection molding machine and can maintain excellent magnetic properties has been desired.

JP 2001-85209 A (Claims) JP 2001-123067 A (Claims) JP 2001-240740 A (Claims)

  The object of the present invention was made in view of the above circumstances, and it is possible to avoid molding defects due to the solidification of the composition before the mold cavity is completely filled, and for a bonded magnet having good injection moldability. It is providing the composition and the bonded magnet formed by shape | molding this.

  In order to improve the injection moldability of the composition for bonded magnets, the present inventors have made extensive studies in order to achieve the above-described object. As a result, the selection of a resin binder type that can improve the melt fluidity, the resin binder However, it is important to consider the viscosity-temperature dependency when the composition for a bonded magnet melts, and it is important to consider the solidification start temperature and the solidification end temperature of the composition. It was found that by controlling the difference to a specific value or more, good injection moldability can be obtained, and the present invention has been completed.

  That is, according to the first invention of the present invention, in the composition for bonded magnet in which the rare earth-transition metal magnetic powder (A) is mixed and dispersed in the resin binder (B), the resin binder (B) is polymerized. Contains at least 50% by weight of the entire resin binder (B) of at least one selected from the fatty acid-based polyamide block copolymer (B-1) or the polymerized fatty acid-based polyetheresteramide block copolymer (B-2) Thus, when the temperature of the bonded magnet composition in the molten state is lowered, the temperature at which the viscosity increase rate of the composition starts to increase (solidification start temperature: Ts) and the viscosity increase rate decrease. A bond magnet composition is provided in which a difference ΔT from a starting temperature (solidification end temperature: Tf) is set to 20 ° C. or more.

  According to the second invention of the present invention, in the first invention, the magnetic powder (A) contains a rare earth (Nd or Sm) and a transition metal (Fe and / or Co). A bonded magnet composition is provided.

  According to a third aspect of the present invention, there is provided the bonded magnet composition according to the first aspect, wherein the magnetic powder (A) has an average particle size of 1 to 100 μm.

  According to a fourth aspect of the present invention, there is provided the bonded magnet composition according to the first aspect, wherein the magnetic powder (A) further contains a ferrite magnetic powder.

  According to the fifth invention of the present invention, in the first invention, the polymerized fatty acid-based polyamide block copolymer (B-1) has a skeleton represented by the following general formula (1) as a repeating unit. There is provided a composition for a bonded magnet, which is a block copolymer.

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. M is an integer of 0 to 70, n is an integer of 1 to 150, and x is an integer of 1 to 100).

  According to the sixth invention of the present invention, in the first invention, the polymerized fatty acid-based polyetheresteramide block copolymer (B-2) is a polymerized fatty acid-based polymer represented by the following general formula (1). A bonded magnet composition comprising a polyamide skeleton (a) and a polyetheresteramide skeleton (b) represented by the general formula (2) is provided.

General formula (1)

(In the formula, R _{1 to} R ₄ , m, n, and x 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.) .

  According to the seventh aspect of the present invention, in the first aspect, the polymerized fatty acid-based polyether ester amide block copolymer is a copolymer of the polymerized fatty acid-based polyamide skeleton (a) and the polyether ester skeleton (b). A composition for a bonded magnet is provided in which the polymerization ratio (a) :( b) is 10:90 to 90:10.

  According to the eighth invention of the present invention, in the first invention, a polymerized fatty acid-based polyamide block copolymer (B-1) or a polymerized fatty acid-based polyetheresteramide block copolymer (B-2) is used. Provides a composition for bonded magnets having a number average molecular weight of 1,000 to 50,000.

  According to the ninth invention of the present invention, in the first invention, a polymerized fatty acid-based polyamide block copolymer (B-1) or a polymerized fatty acid-based polyetheresteramide block copolymer (B-2) is used. Is provided with a composition for bonded magnets having an acid value of 3 or less.

  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 an eleventh aspect of the present invention, in the first aspect, the resin binder (B) has a compounding amount of 1 to 50 parts by weight with respect to 100 parts by weight of the composition. A composition for a magnet is provided.

  Furthermore, according to a twelfth aspect of the present invention, there is provided the bonded magnet composition according to the first aspect, wherein the solidification start temperature Ts is 170 ° C. or higher.

  On the other hand, according to the thirteenth aspect of the present invention, there is provided a bonded magnet formed by injection molding the bonded magnet composition according to any one of the first to twelfth aspects.

  According to the fourteenth aspect of the present invention, the bonded magnet composition according to any one of the first to twelfth aspects of the present invention can be produced by using another metal material and / or by injection molding, compression molding or extrusion molding. A bonded magnet formed integrally with an inorganic material part is provided.

  Furthermore, according to the fifteenth aspect of the present invention, there is provided the bonded magnet according to the thirteenth or fourteenth aspect, wherein the injection molding is performed at 265 ° C. or lower.

  Since the viscosity-temperature dependency from the molten state is controlled, the bonded magnet composition of the present invention has a composition before the mold cavity is completely filled, even when the mold temperature is set low. Molding defects caused by solidification of the product can be avoided, and good injection molding can be achieved. Moreover, the bonded magnet injection-molded from the composition of the present invention has good surface properties and magnetic properties.

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

  The bonded magnet composition of the present invention is a bonded magnet composition comprising a rare earth magnetic powder (A) containing a rare earth element and a transition metal and a thermoplastic resin binder (B). When the temperature of the composition is lowered, the solidification start temperature of the composition is Ts (° C.), the solidification end temperature is Tf (° C.), and Ts−Tf is ΔT. The moldability is improved.

1. Magnetic powder As the magnetic powder (A), various magnetic powders used as raw materials for bonded magnets such as ferrite magnetic powder, alnico magnetic powder, rare earth-iron magnetic powder, rare earth-cobalt magnetic powder can be used. However, it is particularly effective if it is a magnetic powder containing a rare earth element that tends to be deteriorated in magnetic properties due to oxidation at a high temperature.
These may be a mixture (hybrid), and are not only anisotropic magnetic powder but also isotropic magnetic powder.

  As rare earth elements, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), Examples include holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), and one or more of these groups are selected and can be used alone or as a mixture. As the rare earth element, Sm, Nd, Pr, Y, La, Ce, Gd and the like are preferable, and either Nd or Sm is particularly preferable.

On the other hand, examples of the transition metal element include iron (Fe), cobalt (Co), nickel (Ni), and manganese (Mn), and one or more are selected from these groups. In addition to this, in transition metal element, you may contain either Cr, V, or Cu. A particularly preferred transition metal element is either Fe or Co.
In addition to the main components of the magnetic powder, C, Al, Si, P, Ca, Ti, Mn, Ni, Zn, Ga, Zr, Nb, Mo, Ag, In, Sn, Hf, Ta, W, When one or more selected from Re, Os, Ir, Pt, or Au is added to the magnetic powder in an amount of 7% by weight or less, the heat resistance of the magnetic powder can be improved.

As the rare earth-transition metal magnetic powder, for example, one kind selected from rare earth-cobalt, rare earth-iron-boron, rare earth-iron-nitrogen magnetic powder, or a mixture of two or more kinds can be used. Rare earth-iron-nitrogen based magnetic powder is preferred.
For example, the magnetic powder has a Th ₂ Zn ₁₇ type crystal structure, which is a transition metal having 20 to 25% by weight of Sm, 2.1 to 4.0% by weight of N, and the balance being essentially Fe as an essential element. It is desirable to have an intermetallic compound.
If Sm is less than 20% by weight, the coercive force HcJ of the bonded magnet is reduced, and if it exceeds 25% by weight, the residual magnetic flux density Br of the bonded magnet is reduced, while N is less than 2.1% by weight or 4.0. When the weight percentage is exceeded, the coercive force HcJ of the bonded magnet decreases. If 30% by weight or less of the remaining Fe is replaced with Co, the saturation magnetization and the Curie temperature of the magnetic powder increase, and the temperature coefficient α (Br) of the bonded magnet can be kept low.
As another magnetic powder, 20 to 25% by weight of Sm, 3.5 to 5.5% by weight of N, 1.0 to 10% by weight of Mn, and the balance is essentially composed of Fe as an essential element. It is desirable to include an intermetallic compound having a Th ₂ Zn ₁₇ type crystal structure, which is a metal.
If the Sm is less than 20% by weight, the coercive force HcJ of the bonded magnet is reduced, and if it exceeds 25% by weight, the residual magnetic flux density Br of the bonded magnet is decreased, while N is less than 3.5% by weight. If it exceeds 5% by weight, the coercive force HcJ of the bonded magnet is lowered. If 30% by weight or less of the remaining Fe is replaced with Co, the saturation magnetization and the Curie temperature of the magnetic powder increase, and the temperature coefficient α (Br) of the bonded magnet can be kept low.

The physical properties of the rare earth-transition metal magnetic powder are not particularly limited, but from the viewpoint of the melt fluidity of the obtained bonded magnet composition, the orientation of the magnetic powder, the filling rate, etc., the rare earth-transition metal magnetic The average particle size of the powder is preferably 1 to 100 μm. Furthermore, 1-50 micrometers is preferable and it is more preferable that it is 1-10 micrometers.
However, the anisotropic Nd—Fe—B based magnetic powder produced by the HDDR method has a case where the magnetic properties may be lowered when the average particle size is 0.1 to 10 μm. It is preferable to be set to ˜100 μm.

  In addition, in the magnetic powder containing rare earth elements, it is desirable to use a powder whose surface is uniformly coated with a metal compound film such as Zn or a phosphate film having an average of 3 to 100 nm. The phosphate coating is a composite phosphate containing at least iron phosphate and a rare earth element phosphate, and is a coating that protects the surface of the magnetic powder. If the average thickness of the phosphate coating is less than 3 nm, sufficient weather resistance cannot be obtained, and if it exceeds 100 nm, the magnetic properties deteriorate and the kneading properties and moldability also deteriorate.

In the present invention, one or more types of magnetic powders of ferrite magnetic powders such as Sr ferrite and Ba ferrite and metal magnetic material powders such as alnico and iron chromium cobalt are used in accordance with the required magnetic properties. A powder mixed with the material powder can be used.
The mixing ratio of the ferrite magnetic powder to the rare earth-transition metal magnetic powder can be arbitrarily set. However, if the rare earth magnetic powder is set to be larger than the target magnetic characteristics, the total amount of the rare earth magnetic powder and the ferrite magnetic powder is set. Therefore, a composition for a bonded magnet having a low melt viscosity can be obtained, and conversely, if a large amount of ferrite is set, the cost performance of the composition can be improved.

2. Resin binder The resin binder used in the present invention is a specific polyamide resin. When the temperature is lowered after the bonded magnet composition containing the resin binder is melted, the rate of increase in the viscosity of the composition is increased. The difference between the temperature at which the viscosity starts to increase (solidification start temperature: Ts) and the temperature at which the rate of increase in viscosity begins to decrease (solidification end temperature: Tf), that is, Ts−Tf (ΔT) is 20 ° C. or more. Adopt what will be.

In general, in a composition for a bonded magnet in a molten state, the viscosity η ^* increases as the temperature decreases, and particularly has a tendency to increase rapidly during the solidification process of the composition.

In the present invention, as described above, when the temperature of the melted bonded magnet composition is lowered, the temperature at which the increasing rate of the viscosity η ^* starts to increase is increased by the solidification start temperature Ts (° C.) and η ^* . Is defined as the solidification end temperature Tf (° C.). Although the conventional MFR (melt flow rate) measurement method based on JIS K 7210 and ASTM D-1238 could not be sufficiently evaluated, the evaluation of the composition for bonded magnets according to the present invention is generally The characteristics closer to the moldability when the bonded magnet composition is injection molded using a typical injection molding apparatus can be defined.

Here, the solidification start temperature Ts is determined by examining the temperature dependence of the melt viscosity using a rotational viscometer. That is, in the present invention, first, a bonded magnet composition is placed between parallel plates of MR-300 solid meter (manufactured by Rheology Co., Ltd.), and heated to 250 ° C. in an inert gas atmosphere. Melt. At this time, the diameter of the parallel plate is 18 mm, and the gap is 1.2 mm. Next, the parallel plate was vibrated at a frequency of 1 Hz and an amplitude of 0.3 °, and 2 ° C./min. In while cooling by measuring the loss modulus G "and the storage modulus G 'of the composition may be measured a temperature change of the viscosity eta ^{* (complex} viscosity). Here, the viscosity eta ^*, the following Η ^* = (G ′ ² + G ″ ² ) ^1/2 / ω (where ω is an angular frequency)

Here, the viscosity-temperature dependence of the composition for bonded magnets will be described with reference to FIG. When the resin binder that can be used in the present invention is lowered in temperature after the bonded magnet composition prepared using this resin binder is melted, it looks like a curve that connects the plots of ○ or Δ shown in FIG. Viscosity changes.
The temperature at which the viscosity starts to change suddenly can be read from the state where the rate of increase in viscosity is small (two straight lines can be drawn). A resin having a wide interval between these two points, that is, a resin having a difference ΔT between the solidification start temperature Ts and the solidification end temperature Tf of 20 ° C. or more has a moderate viscosity-temperature dependency and can be used in the present invention. It is a binder. A composition for a bonded magnet using such a binder is in a supercooled state when injected into a mold under a high shearing force, and does not impair the melt fluidity until the temperature becomes considerably lower than Tf. It is estimated that good moldability can be obtained.

  The composition containing the resin binder that can be used in the present invention has a solidification start temperature Ts of 170 ° C. or higher. Among these, those having a solidification start temperature Ts of 190 to 215 ° C are preferable, and those having a solidification starting temperature Ts of 195 to 210 ° C are particularly preferable. If the solidification start temperature Ts is less than 170 ° C., there is a problem of load deflection strength of the bonded magnet, which is not preferable. On the other hand, if ΔT is less than 20 ° C., molding defects occur when the mold temperature is set low, such being undesirable.

  The type of resin binder that can be used is not particularly limited as long as it meets such conditions, but a polymerized fatty acid-based polyamide block copolymer having a soft segment in a molecular chain or a polymerized fatty acid-based polyether ester amide. It preferably contains 50% by weight or more of a thermoplastic resin such as a block copolymer (hereinafter, these are also referred to as a polymerized fatty acid-based poly (ether ester) amide block copolymer or simply a block copolymer).

  That is, the resin binder (B) that can be used in the present invention is a polymerized fatty acid-based polyamide block copolymer (B-1) having a skeleton represented by the general formula (1) as a repeating unit, or this Either a block copolymer (B-1) or 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 thereof Is included.

  The polymerized fatty acid-based polyamide block copolymer (B-1) is represented by the general formula (1).

General formula (1)

However, 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 from 6 to 44, _{R 2} is 6 carbon atoms A dicarboxylic acid residue selected from one or more of 22 aliphatic or aromatic dicarboxylic acids, R ₄ is 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 0 to 70, n is an integer from 1 to 150, and x is an integer from 1 to 100.

The polymerized fatty acid-based polyether ester amide block copolymer (B-2) is a polymerized fatty acid-based polyamide block copolymer having a skeleton represented by the general formula (1) as a repeating unit (wherein R ₁ ˜R ₄ , m, n, and x are the same as described above) or an oligomer thereof, 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 comprising 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 (B-1) or polymerized fatty acid-based polyetheresteramide block copolymer (B-2) preferably has a number average molecular weight of 1,000 to 50,000. 5,000 to 25,000 are more preferable, and 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 may be separated from the magnetic powder during the molding process, or the strength of the bond magnet formed from the composition may be significantly reduced. When the molecular weight exceeds 50,000, sufficient melt fluidity cannot be obtained during molding.

  The polymerized fatty acid-based polyamide block copolymer (B-1) is a resin comprising only a polymerized fatty acid-based polyamide skeleton, and among these skeletons, a hard skeleton of a dicarboxylic acid having an aromatic ring or a short hydrocarbon chain. And a resin in which a polymerized fatty acid soft skeleton is block-polymerized is preferable.

  The polymerized fatty acid-based poly (ether ester) amide block copolymer may be 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, and the like. If an amino group is present at the end of the resin binder, it reacts with non-oxidized iron, so the type of polymerized fatty acid-based poly (ether ester) amide block copolymer depends on the iron content and particle size of the magnetic powder. And carefully choose the amount.

  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 particularly preferably 80:20 to 50:50.

  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 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. In addition, although mixing of dicarboxylic acid (b) is preferable, its use may be omitted.

  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. It is done.

  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. Mixtures of these and ester derivatives are also used.

The dicarboxylic acid (b) that can be used together with the polymerized fatty acid is an aliphatic or aromatic dicarboxylic acid having 6 to 22 carbon atoms and ester derivatives thereof. 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 Xylenedicarboxylic 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.
In addition, caprolactam may be blended.

  (I) 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 are the above-mentioned polymerized fatty acid-based polyamide block copolymer (B-1 ) In a proportion satisfying the structural formula. For example, the weight ratio of (a) to (b) is (b) / (b) is 0.3 to 5.2, and the total amino groups are substantially equivalent to the total carboxyl groups. To polycondense. 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.

  For example, in a reaction vessel sufficiently substituted with nitrogen, (a) a polymerized fatty acid, (b) azelaic acid and / or sebacic acid, and (c) hexamethylene diamine are combined. The weight ratio of (a) to (a) / (b) is 0.3 to 5.2, and all amino groups are charged to be substantially equivalent to all carboxyl groups, and a predetermined amount of molecular weight regulator And in the presence of a small amount of a polycondensation catalyst (such as phosphoric acid), the temperature is raised to 200 to 280 ° C. and reacted for 1 to 3 hours, and further reacted for 0.5 to 2 hours under a reduced pressure of about 160 mmHg. A polyamide copolymer having a high molecular weight and excellent flexibility can be 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.

  As the polymerized fatty acid-based polyamide block copolymer (B-1) thus produced, “PA-30R”, “PA-30M”, “PA-30”, manufactured by Fuji Kasei Kogyo Co., Ltd., "PA-40M", "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.

  In the present invention, such a commercial product can be used, but by synthesizing by changing the raw material input amount to be polycondensed, the resin binder soft segment (having a flexible structure exhibiting entropy elasticity at a low glass transition temperature) If the skeleton and the ratio of the component) and the hard segment (the component that constrains the molecules that form a hydrogen bond or a high glass transition temperature phase) are adjusted, one in which Ts and Tf are controlled can be obtained. For example, Ts depends on the skeleton of the hard segment and Tf depends on the skeleton of the soft segment, and the viscosity increasing behavior from Ts to Tf can be controlled by the ratio thereof. The polymerized fatty acid-based polyamide block copolymer (B-1) does not have a soft segment, but a polymer of a diamine and an unsaturated fatty acid exhibits a flexible soft segment-like behavior.

  On the other hand, this polymerized fatty acid-based polyetheresteramide block copolymer (B-2) is composed of (a) and (c) among the specific polymerized fatty acid (a), dicarboxylic acid (b), and diamine (c). The above-mentioned polymerized fatty acid-based polyamide block copolymer oligomer obtained by mixing and polycondensing the two components (i), (b) and (c) is mixed with polyoxyalkylene glycol or dihydroxy carbonized It is produced by reacting hydrogen (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.

  As the polymerized fatty acid-based polyether ester amide block copolymer (B-2) thus produced, “TPAE8”, “TPAE10 · C”, “TPAE10 · HP” manufactured by Fuji Kasei Kogyo Co., Ltd. And “TPAE12”.

  In the case of this polymerized fatty acid-based polyether ester amide block copolymer (B-2), the resin binder soft segment (polyether ester skeleton) and the hard binder are changed in the same manner as described above by changing the amount of raw material to be polycondensed. If the kind and ratio of the segment (polymerized fatty acid polyamide skeleton) are adjusted, one in which Ts and Tf are controlled can be obtained.

  From the viewpoint of loosening the viscosity-temperature dependency and improving the injection moldability, the polyether ester skeleton (a) of the polymerized fatty acid-based polyetheresteramide block copolymer (B-2) and the polymerized fatty acid-based The copolymerization ratio (a) :( b) with the polyamide skeleton (b) is preferably appropriately changed between 10:90 and 90:10. In particular, (a) :( b) is preferably 80:20 to 50:50. If the polymerized fatty acid-based polyamide skeleton (a) is less than 10, the resin becomes too soft and the required strength of the molded product may not be obtained, and if it exceeds 90, the molded product may become brittle.

  These polymerized fatty acid-based polyamide block copolymers (B-1) and polymerized fatty acid-based polyetheresteramide block copolymers (B-2) can be used as long as the above conditions are satisfied. It is desirable that the tensile yield stress is 18 MPa or less, preferably 17 MPa or less, and the tensile fracture stress is 50 MPa or less, 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.

In addition, these block copolymers preferably have an acid value representing the amount of the free acid of 3 or less. Here, the acid value is expressed as the number of mg of potassium hydroxide required to neutralize 1 g of the polyamide copolymer of the sample according to JIS K5601-2-1. Specifically, the sample was dissolved in a solvent of toluene: normal butanol = 2: 1, added with a phenolphthalein indicator solution, and titrated with a 0.1 mol / L potassium hydroxide methyl alcohol solution. Desired.
An acid value exceeding 3 is not preferable because the amount of free acid contained in the block copolymer is large, so that the kneading torque increases and the fluidity of the composition decreases.

  By the way, if ΔT (° C.) of the bonded magnet composition is 20 ° C. or more, the above-mentioned polymerized fatty acid-based poly (ether ester) amide block copolymer is used as a main component, and ordinary nylon 12 or A thermoplastic resin such as nylon 6 can be mixed as a subordinate component.

  Examples of the resin that can be blended as a subsidiary component include nylon 6, nylon 12, nylon 6-12, 4-6 nylon, and modified nylon, polyamide resins such as nylon elastomer, and polyolefin resins 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 Examples thereof include resins and polyether ether ketones.

  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, it is not desirable to blend these thermoplastic resins in an amount of 50% by weight or more with respect to the polymerized fatty acid-based poly (ether ester) amide block copolymer as the main resin binder. When 50% by weight or more is blended, both elongation at break and magnetic properties are lowered, and flexibility under a low temperature environment may not be improved.

According to the test conducted by the present inventors, the composition blended with the resin binder described in the above-mentioned prior document (Patent Document 1) has an improvement tendency in moldability, but the solidification start temperature is Since the resin binder was lower than that of the composition of the invention, ΔT was narrowed, the surface of the molded article remained rough, and sufficient effects were not obtained.
In addition, in the above-mentioned prior art documents (Patent Documents 2 and 3), if too much polymerized fatty acid poly (ether ester) amide resin is added to the whole magnet composition, the magnetic powder content is relatively lowered. However, since the polymerized fatty acid poly (ether ester) amide block copolymer according to the present invention has good mechanical properties, the blending amount is 50% by weight of the resin binder. If it is set as the above, generation | occurrence | production of the stress crack of the bond magnet etc. which arise from the difference of the thermal expansion coefficient of a bond magnet and a yoke material in an integrally molded article etc. can be suppressed.

  The resin binder of the present invention includes a silane compound in the main resin of the (B-1) polymerized fatty acid-based polyamide block copolymer and / or (B-2) the polymerized fatty acid-based polyetheresteramide block copolymer. Can be combined so as to be 1% by weight or more, preferably 3% by weight or more.

(Silane compounds)
In the present invention, the silane compound is an alloy of a rare earth and a transition metal such as alkoxysilane (having no functional group), halogenated silane (chlorosilane, etc.), silazane, etc., or an inorganic coating component on the surface thereof. A silicon-containing compound that has a reactive group but does not react with the organic component of the resin or has low reactivity. Accordingly, silicon-containing compounds (that is, silane coupling agents) having groups reactive to the inorganic coating component of the magnetic powder and having high reactivity with the organic component of the resin are excluded.

  The silane compound reacts only with the inorganic component of the magnetic powder. On the other hand, when a silane coupling agent is used, it also reacts with the organic group of the resin binder. As it increases, the viscosity of the compound increases and the fluidity also decreases. By surface treatment with the coupling agent, when the amount of filler is large, the torque during kneading is increased, the protective film on the surface of the magnetic powder is peeled off, and the kneading temperature is increased, The shear heat generation may cause problems such as deterioration of the magnetic powder and lowering the coercive force, lowering the fluidity during injection molding, and deterioration of the magnetic powder due to high-temperature injection. Thus, in such cases, the use of coupling agents is substantially limited.

  Examples of the alkoxysilane include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, and diphenyldimethoxy. Examples include silane, diphenyldiethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, trifluoropropyltrimethoxysilane, heptadecatrifluorodecyltrimethoxysilane, and the like. These silane compounds can be used alone or mixed with each other.

  Specifically, “KBM04”, “KBM13”, “KBM22”, “KBM103”, “KBM202SS”, “KBE04”, “KBE13”, “KBE22” manufactured by Shin-Etsu Chemical Co., Ltd. “KBE103”, “KBE202”, “KBM3063”, “KBE3063”, “KBM3103”, “KBM3103C”, “KBM7103”, “KBM7803”, manufactured by Nippon Unicar Co., Ltd., “A” -137 "," A-162 "," A-163 "," AZ-6177 "," A-1230 "," Y-11597 ", and the like.

  Examples of the halogenated silane include methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, triethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, trifluoropropyltrichlorosilane, heptadecafluorodecyltrichlorosilane, and the like. Specifically, “KA13”, “KA12”, “KA22”, “KA31”, “KA103”, “KA202”, “KA7103”, “KA7803” manufactured by Shin-Etsu Chemical Co., Ltd. Etc.

  Examples of silazane include hexamethyldisilazane, hexaethyldisilazane, trimethyltriethyldisilazane, cyclosilazane, polycyclosilazane, and specifically, “HMDS3” manufactured by Shin-Etsu Chemical Co., Ltd. can be exemplified.

3. Method for Producing Bond Magnet Composition The composition for a bond magnet of the present invention comprises (1) preparing the magnetic powder and coating it with a metal compound or phosphate compound having a melting point of 150 to 500 ° C. After coating with an agent, (2) a resin binder is mixed and magnetic powder is dispersed.

(1) Coating with metal compound or phosphoric acid compound As a surface treatment method of the present invention, magnetic powder is surface-treated with a metal compound or phosphoric acid compound having a melting point of 150 to 500 ° C. in advance, and then coupled with magnetic powder. Can be treated with an agent.

(Metal compound)
As the metal compound, as proposed by the applicant in Japanese Patent Application Laid-Open No. 2001-207201, a Zn-containing film is formed after reaction or non-reaction itself, such as zinc (Zn), and R—T— The surface of the N-based magnetic powder can be coated substantially uniformly, and specific examples include Zn, tin (Sn), indium (In), and lead (Pb).

  The metal compound requires 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 reacting or not reacting and is coated on the surface of the rare earth-transition metal 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.
Ammonium phosphate, ammonium magnesium phosphate, etc. Furthermore, zinc phosphates that form hopite, phosphoferrite, etc. on the surface of magnetic powder, zinc phosphates that form scholzeite, phosphophyllite, hopite, etc., manganese helio 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.

  Of these, zinc phosphate-based, manganese phosphate-based, and iron phosphate-based compounds exhibit desirable performance because these metal elements form a protective film on the surface of magnetic powders containing rare earth metals. It is thought to be easy. These phosphoric acid compounds may be used alone or in combination.

  As proposed by the present applicant, the weather resistance of the rare earth-iron-based magnetic powder having a surface uniformly coated with a metal compound film or an average 3-100 nm phosphate film is significantly improved ( JP 2003-7521 A). The composition for bonded magnets obtained by kneading this magnetic powder with conventional polyamide such as nylon 6, nylon 12, or nylon 6-12, although the weather resistance is greatly improved, melt flowability and molding processing However, the mechanical strength of the magnet obtained by molding is slightly reduced. However, this is improved by the present invention using a polymerized fatty acid-based poly (ether ester) amide block copolymer as a main resin binder.

Among the rare earth-iron 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), 0.5 to 5.0% by weight of O (oxygen), and the balance is T (transition metal element and unavoidable impurities), and the content of H (hydrogen), which is an unavoidable impurity, is 0.00. When a rare earth-iron-nitrogen (RTN) -based magnetic powder having a Th ₂ Zn ₁₇ type or Th ₂ Ni ₁₇ type crystal structure of 3 wt% or less is selected, the surface properties of the molded body are also It is more effective in that it is good and melt flowability, molding processability, and mechanical strength of the molded body are improved.

  Here, the rare earth element (R) is contained in an amount of 20 to 25% by weight, preferably 23 to 25% by weight. When R is less than 20% by weight, the remanent magnetization and coercive force of the magnetic powder are lowered, and when it exceeds 25% by weight, the remanent magnetization and weather resistance of the magnetic powder are lowered. N (nitrogen) is contained in an amount of 2.1 to 3.9% by weight, preferably 2.8 to 3.5% by weight. If N is less than 2.1% by weight or more than 3.9% by weight, the residual 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% by weight, preferably 0.3 to 1.0% by weight. If P is less than 0.2% by weight, the weather resistance and heat resistance of the magnetic powder are inferior, and if it exceeds 2.0% by weight, the residual magnetization decreases, which is not preferable. Further, O (oxygen) is 0.5 to 5.0% by weight, preferably 1.0 to 3.0% by weight. When O is less than 0.5% by weight, the phosphate film on the surface of the magnetic powder is not sufficiently formed. In addition to poor weather resistance and heat resistance, surface activity is high. There is a risk. On the other hand, if it exceeds 5.0% by weight, the remanent 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% by weight, preferably 0.1% by weight or less. H adversely affects the weather resistance, and if it exceeds 0.3% by weight, the weather resistance decreases and the coercive force also decreases, so it is desirable to eliminate it as much as possible.

Further, the physical properties of the rare earth-transition metal magnetic powder are not particularly limited, but from the viewpoint of the melt fluidity of the obtained bonded magnet composition, the orientation of the magnetic powder, the filling rate, etc., the rare earth-transition metal The average particle size of the system magnetic powder is preferably 1 to 100 μm. Among these, 1-50 micrometers is preferable and it is more preferable that it is 1-10 micrometers. When the average particle size is 1 to 10 μm, the composition of the components is set to the above range, whereby a rare earth-transition metal (R—Fe—N) magnetic powder having a coercive force at room temperature of 400 kA / m or more is obtained. Here, if the average particle diameter is less than 1 μm, the residual magnetization of the magnetic powder is lowered, and if it exceeds 10 μm, the coercive force at room temperature may be less than 400 kA / m.
However, as described above, with respect to the anisotropic Nd—Fe—B magnetic powder produced by the HDDR method, if the average particle size is 0.1 to 10 μm, the magnetic properties may be lowered. The thickness is preferably 100 μm.

(Coupling agent)
The magnetic powder coated with a metal compound or phosphate can be further coated with a 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. 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- Examples include γ-aminopropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane. 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, and then fixed to the magnetic powder more stably by heating and drying. 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 or the like, 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, if necessary, a surface treatment step with a metal compound or a phosphoric acid compound is performed in advance to coat the magnetic powder, and then the magnetic powder is treated with a coupling agent. However, the magnetic powder, the resin binder, and the coupling agent may be mixed together. However, in order to obtain a more reliable surface-treated film, it is desirable that the magnetic powder is pulverized or the like, and the magnetic powder is previously treated with a coupling agent and then mixed with a resin binder.

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

  The blending amount of the resin binder (B) is not particularly limited, but is 1 to 50 parts by weight, preferably 3 to 50 parts by weight with respect to 100 parts by weight of the composition. Furthermore, 5 to 30 parts by weight, particularly 7 to 20 parts by weight is more preferable. If the resin binder (B) is less than 1 part by weight, not only will the kneading torque increase significantly, the fluidity will be lowered and it will be difficult to mold, but the magnetic properties will be insufficient, and if it exceeds 50 parts by weight, It is not preferable because desired magnetic properties cannot be obtained.

  In the present invention, a remarkable effect is obtained when the magnetic powder is highly filled as described above. However, according to the composition for a bonded magnet of the present invention, the blending amount of the magnetic powder is less than 80 parts by weight. Even in this case, it is advantageous in terms of 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)
In the composition for bonded magnets, a reactive diluent, an unreactive diluent, a thickener, a lubricant, a release agent, an ultraviolet absorber, a flame retardant, and various stabilizers are used within the range not impairing the object of the present invention. Such other additives can be blended.

Examples of the reactive diluent include styrene, fatty acid diglycidyl ether, ethylene glycol glycidyl ether, phenyl glycidyl ether, and glycerin polyglycidyl ether.
Examples of the unreactive diluent include alcohols such as ethanol and isopropanol.

Examples of the thickener include beryllium oxide, magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, and zinc oxide.
Examples of lubricants include waxes such as paraffin wax, liquid paraffin, polyethylene wax, polypropylene wax, ester wax, carnauba, and microwax, stearic acid, 1,2-oxystearic acid, lauric acid, palmitic acid, and oleic acid. Fatty acids such as 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, methylenebis Aliphatic 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, fatty acid amides such as N-stearyl stearic acid amide, butyl stearate, etc. Fatty acid 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 oils, Fluorine compounds such as fluorine-based grease and fluorine-containing resin powder, and inorganic compound powders such as silicon nitride, silicon carbide, magnesium oxide, alumina, silicon dioxide, molybdenum disulfide The blending amount of the lubricant is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the magnetic powder.
Examples of the mold release agent include zinc stearate, a mixed system of a metal stearate and zinc stearate.

Examples of the ultraviolet absorber include benzophenone series such as phenyl salicylate, p-tert-butylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 3-2′-dihydroxy-4-methoxybenzophenone; 2 Benzotriazoles such as-(2'-hydroxy-5'-methylphenyl) benzotriazole and 2- (2'-hydroxy-3 ', 5'-ditert-butylphenyl) benzotriazole; oxalic anilide derivatives and the like It is done.
Examples of the flame retardant include antimony trioxide, sodium antimonate, organic bromine compounds, chlorinated paraffin, and chlorinated polyethylene.

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 compounding amount of the stabilizer is usually 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight with respect to the total amount of the magnetic powder.

  The addition amount of these additives is appropriately selected according to the type of resin binder and the type of magnetic powder, and is not particularly limited, but is usually the total for 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 clay such as mica, whisker or talc, carbon fiber, and 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. By adding a filler such as mica or whisker, the mechanical strength of the bonded magnet can be supplemented.
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.

4). Bond magnet The above composition for a bond magnet is heated at a temperature of 190 to 280 ° C, and then formed into a bond magnet of the present invention having a desired shape.
By molding by injection molding, compression molding, extrusion molding, rolling molding, transfer molding, etc., not only the magnetic properties and the degree of freedom of shape, but also excellent rust resistance properties, mechanical strength, flexibility, heat resistance, etc. The bonded magnet of the present invention is obtained.

The method for molding the composition for bonded magnets of the present invention is not particularly limited, but injection molding that is excellent in melt flowability, high magnetic properties and high mechanical strength is most effective.
In the injection molding, the bonded magnet composition is molded under the condition that the maximum history temperature is 265 ° C. or lower, preferably 260 ° C. or lower, more preferably 250 ° C. or lower. When the maximum history temperature exceeds 265 ° C., there is a problem in that the magnetic characteristics are deteriorated, which is not preferable.

  When the bonded magnet of the present invention is manufactured by integral molding, not only the strength and accuracy of the product are improved, but also mass productivity is improved, and the characteristics of the bonded magnet are effectively realized. That is, by integrally molding with a metal material and / or inorganic material part, there is a problem of bond magnet cracking due to the difference in coefficient of linear expansion between the bond magnet and the metal material and / or inorganic material part in the cooling process after molding. Is significantly improved. The problem of cracking of the integrally molded product by the heat cycle test is remarkably improved. The metal material and the inorganic material component are a yoke material (back yoke), a hub, a shaft, and the like, and the size and shape thereof are not particularly limited.

For example, a mold 1 having a cavity 2 and a core 3 as shown in FIG. 2 is used, and a back yoke (for example, a steel ring 4) such as a columnar or cylindrical iron or silicon steel plate is provided on the inner or outer periphery thereof. ) And these are integrally molded to manufacture the cylindrical bonded magnet 10 (FIG. 3 or FIG. 4).
Here, when the outer diameter of the bonded magnet is Do and the inner diameter is Di, the thickness is divided by Do, and when a cylindrical bonded magnet having (Do-Di) / 2Do of 2% or more is molded at 80 ° C. No cracking occurs even after 50 heat cycle tests in which high temperature holding for 1 hour and low temperature holding for 1 hour at −30 ° C. are repeated. In this heat cycle test, the switching time between 80 ° C. and −30 ° C. is 1 hour.
When the value obtained by dividing the wall thickness by Do (Do-Di) / 2Do is less than 2%, the bonded magnet is broken under these heat cycle test conditions. The value obtained by dividing the wall thickness by Do is preferably 3% or more, and particularly preferably 5% or more. By setting this value to 3% or more, it becomes possible to obtain a bonded magnet that does not crack even after 200 heat cycle tests.

  In addition, if there are molding defects such as pores in the molded body, stress concentrates on the defective part and cracks easily occur.Therefore, adjust the number of gates and air vents for injection molding and their arrangement to eliminate defects. It is also important to reduce as much as possible. Furthermore, after mold clamping, the mold cavity and sprue / runner are reduced in pressure via an air vent, and then injection molded to further reduce molding defects. Even after 100 heat cycle tests A bonded magnet that does not break can be obtained. Here, the cavity portion may be decompressed to a gauge pressure of −0.02 MPa or less, preferably −0.05 MPa or less, more preferably −0.07 MPa or less.

  If the rotor shaft is inserted into the center of the obtained integrally molded magnet and this integrally molded product is used as a small motor, the performance of cameras, video, OA equipment, automobiles and other precision equipment will be greatly improved. Can do.

  When the bonded magnet composition contains anisotropic magnetic powder, a magnetic circuit is incorporated in the mold of the molding machine, and an orientation magnetic field is applied to the molding space (mold cavity) of the composition. An anisotropic bonded magnet can be manufactured. At this time, a bond magnet having high magnetic properties can be obtained by setting the orientation magnetic field to 400 kA / m or more, preferably 800 kA / m or more. When the composition for bonded magnets contains isotropic magnetic powder, it is carried out without applying an orientation magnetic field to the molding space (mold cavity) of the composition.

  Examples and Comparative Examples of the present invention are shown below, but the present invention is not limited to these Examples.

Various magnetic powders used, coupling agents, resin binder components, and evaluation methods for the performance of bonded magnets using them are as follows.
(1) Component Magnetic powder Magnetic powder 1, Sm-Fe-N system (trade name: SFN fine powder B, manufactured by Sumitomo Metal Mining Co., Ltd.), Sm 24.5 wt%, N 3.4 wt%, balance Fe; Average particle size: 2.6 μm. A magnetic powder having a Th ₂ Zn ₁₇ type crystal structure obtained by nitriding and pulverizing Sm—Fe alloy powder obtained by a reduction diffusion method using samarium oxide and iron powder as raw materials with a mixed gas of ammonia and hydrogen.
Magnetic powder 2-1, isotropic Nd—Fe—B system (manufactured by Magnequench International) “trade name: MQP-B”, average particle size 80 μm.
Magnetic powder 2-2, anisotropic Nd—Fe—B system (manufactured by Sumitomo Special Metal Co., Ltd.), “trade name: HDDR-B”. Average particle size: 69 μm.
Magnetic powder 2-3, anisotropic Nd—Fe—B system (manufactured by Aichi Steel Co., Ltd.), “trade name: MFP-12”. Average particle size: 109 μm.
Magnetic powder 3, Sm-Co magnetic powder (manufactured by Shin-Etsu Chemical Co., Ltd.), average particle size: 83 μm.
・ Magnetic powder 4, Sr ferrite (trade name: HF-330, manufactured by Dowa Mining Co., Ltd.)

Coupling agent ・ Silane coupling agent (aminopropyltrimethoxysilane, trade name: SH6020, manufactured by Toray Dow Corning)

Resin binder Copolyamide A
By using oleic acid, linoleic acid, azelaic acid, sebacic acid, and hexamethylenediamine as raw materials and reacting at 250 ° C. in a nitrogen atmosphere while stirring with stearic acid, a melting point of 192 ° C., a crystallization temperature of 150 ° C., and an MI value of 690 g / 10 min. A copolymer polyamide (polymerized fatty acid-based polyamide block copolymer) having a number average molecular weight of about 11,000 was obtained. Here, the MI value was measured according to JIS K 7210 (measured at 230 ° C. and a load of 21.2 N. The same applies hereinafter). The acid value was 2.5.
・ Copolymer polyamide B
Oleic acid, linoleic acid, azelaic acid, sebacic acid, and hexamethylenediamine were used as raw materials and reacted with stearic acid at 250 ° C. under a nitrogen atmosphere to obtain a melting point of 175 ° C., a crystallization temperature of 131 ° C., and an MI value of 710 g. / 10 min. A copolymerized polyamide (polymerized fatty acid-based polyamide block copolymer) having a number average molecular weight of about 10,000 was obtained. The acid value was 1.2.
・ Copolymer polyamide C
By using oleic acid, linoleic acid, azelaic acid, sebacic acid, hexamethylenediamine as raw materials and reacting at 250 ° C. in a nitrogen atmosphere with stirring with stearic acid, melting point 175 ° C., crystallization temperature 131 ° C., MI value 460 g / 10 min. A copolymerized polyamide (polymerized fatty acid-based polyamide block copolymer) having a number average molecular weight of about 10,000 was obtained. The acid value was 1.9.
-Copolymer polyamide D, polymerized fatty acid polyamide (trade name: PA-30L, manufactured by Fuji Kasei Kogyo Co., Ltd.), number average molecular weight was about 14,000, and acid value was 3.2.
・ Polyamide elastomer A
Polyoxytetramethylene glycol and azelaic acid are added to a polyamide oligomer reacted at 190 ° C in a nitrogen atmosphere using oleic acid, linoleic acid, azelaic acid, sebacic acid, and hexamethylenediamine as raw materials, and the mixture is stirred uniformly. The polymerization was carried out at 270 ° C. Melting point 171 ° C., crystallization temperature 142 ° C., MI value 400 g / 10 min. Thus, a polyamide elastomer A (polymerized fatty acid-based polyether ester amide block copolymer) having a hard segment of 40% and a soft segment of 60% in a weight ratio having a number average molecular weight of about 10,000 was obtained. The acid value was 1.8.
・ Polyamide elastomer B
The melting point was 153 ° C., the crystallization temperature was 122 ° C., and the MI value was 1600 g / 10 min., Except that the blending ratio of polyoxytetramethylene glycol and azelaic acid to the polyamide oligomer was changed. A polyamide elastomer B (polymerized fatty acid-based polyether ester amide block copolymer) having a hard segment of 20% and a soft segment of 80% at a weight ratio of about 6,000 was obtained. The acid value was 2.3.
・ Polyamide elastomer C
The melting point was 201 ° C., the crystallization temperature was 181 ° C., and the MI value was 920 g / 10 min. Except that the blending ratio of polyoxytetramethylene glycol and azelaic acid to the polyamide oligomer was changed. A polyamide elastomer C (polymerized fatty acid-based polyether ester amide block copolymer) having a hard segment of 60% and a soft segment of 40% in a weight ratio of about 10,000 in the number average molecular weight was obtained. The acid value was 2.0.
Polyamide elastomer D, polymerized fatty acid-based polyether ester amide block copolymer (trade name: TPAE8, manufactured by Fuji Kasei Kogyo Co., Ltd.), number average molecular weight of about 12,000. The acid value was 2.8.
-Copolymer nylon (trade name: Grilon C, manufactured by MMS Japan Co., Ltd.), number average molecular weight of about 14,000.
Polyamide 12A (trade name: 3014U manufactured by Ube Industries, Ltd.), tensile yield stress 43 MPa, tensile fracture stress 55 MPa, number average molecular weight about 13000.
Polyamide 12B (trade name: A1709P, manufactured by Daicel Huls Co., Ltd.), number average molecular weight of about 13,000.

(2) Testing / evaluation method Solidification temperature The composition is placed between parallel plates of MR-300 solid meter (manufactured by Rheology Co., Ltd.) and heated to 250 ° C. in an inert gas atmosphere to melt the composition. I let you. The parallel plate had a diameter of 18 mm and a gap of 1.2 mm. The parallel plate is vibrated at a frequency of 1 Hz and an amplitude of 0.3 °, and 2 ° C./min. The temperature change of the viscosity η ^* of the composition was measured while being cooled at. The temperature at which the rate of increase in viscosity η ^* begins to increase is defined as the solidification start temperature Ts (° C.), and the temperature at which the increase in η ^* is substantially saturated is defined as the solidification end temperature Tf (° C.).
-Composition fluidity | liquidity evaluation According to JISK7210, it measured with the cylinder temperature of 250 degreeC, and the load of 21.6kgf using the orifice of (phi) 2.1mm and length 8mm.

Magnet properties The composition was injection molded into a cylindrical shape of φ20 × 13 mm at 210 to 240 ° C. An orientation magnetic field of 1600 kA / m is applied to the mold cavity in the 13 mm direction. Note that the Nd-Fe-B magnetic powder of the magnetic powder 2-1 is an isotropic magnetic powder, and thus was molded without applying an orientation magnetic field. The obtained bonded magnet was pulse magnetized at 3200 kA / m, and the maximum energy product (BH) max. Was measured.

-Injection moldability A plate-shaped magnet of 60 x 7 x 37 mm was molded with a hydraulic injection molding machine with a clamping force of 70 t. The gate is arranged as a two-point pinpoint gate on a 60 × 7 mm surface. The mold temperature is set to 10 ° C. by circulating cooling water. The molding temperature was adjusted in the range of 220 to 270 ° C. under conditions where the pressure was set to 50% and the speed was set to 20%, and injection was performed at a relatively low speed, and the surface properties of the obtained ring-shaped injection molded magnet were observed.
A sample with very good surface properties was marked with ◎, a sample with good surface properties was marked with ○, a sample with rough magnet surfaces was marked with Δ, and a sample with short shots that could not be injected and filled was marked with ×.

[Examples 1 to 24]
Aminopropyltrimethoxysilane was dissolved in an ethanol aqueous solution and mixed with magnetic powder and a mixer. Heating and drying at 100 ° C. while continuing stirring gave a surface-treated magnetic powder. Next, the obtained magnetic powder and a thermoplastic resin binder (main resin: copolymerized polyamide or polyamide elastomer) were kneaded at 200 ° C. using a lab plast mill, and the obtained kneaded product was pulverized with a plastic pulverizer. . The pulverized kneaded product was put into an injection molding machine to produce an injection molded magnet.
Magnetic powder used, thermoplastic resin binder and blending thereof, solidification start temperature Ts, solidification end temperature Tf of the obtained kneaded product, difference ΔT between them, (BH) max of φ20 × 13 mm injection molded magnet, ring-shaped magnet Tables 1 to 3 and Table 7 show the molding temperature and the surface properties.

[Comparative Examples 1 to 17]
In the same manner as in Examples 1 to 24, surface-treated magnetic powder was obtained. Next, the obtained magnetic powder and a thermoplastic resin binder (main resin: polyamide 12A or polyamide 12B) were kneaded at 200 ° C. using a lab plast mill, and the obtained kneaded product was pulverized with a plastic pulverizer. The pulverized kneaded product was put into an injection molding machine to produce an injection molded magnet.
Magnetic powder used, thermoplastic resin binder and blending (composition) thereof, solidification start temperature Ts, solidification end temperature Tf of the obtained kneaded product, difference ΔT between them, (BH) max of φ20 × 13 mm injection molded magnet, Tables 4 to 6 show the molding temperature and surface properties of the ring-shaped magnet.

[Conventional example 1]
91.2% by weight of the surface-treated Sm—Fe—N magnetic powder obtained in Example 1 of the present invention and nylon 12B (trade name: A1709P, manufactured by Daicel Huls Co., Ltd.) 4.0% by weight And 4.0% by weight of copolymer nylon (trade name: Grilon C, manufactured by MMS Japan Co., Ltd.) and antioxidant N, N-bis {3- (3,5-di-t-butyl- 4-Hydroxyphenyl) propionyl} hydrazine 0.4% by weight and a lubricant m-xylylene bis-stearic acid amide 0.4% by weight were mixed and kneaded at 230 ° C. using a Laboplast mill.
Table 6 shows the solidification start temperature Ts, solidification end temperature Tf, difference ΔT, φ20 × 13 mm injection-molded magnet (BH) max, ring-shaped magnet molding temperature, and surface properties of the obtained kneaded product.

[Conventional example 2]
91.2% by weight of the surface-treated Sm—Fe—N-based magnetic powder obtained in Example 1 of the present invention and 5.1% by weight of nylon 12A (trade name: 3014U, manufactured by Ube Industries, Ltd.) Polymerized fatty acid based polyamide elastomer (trade name: TPAE8, manufactured by Fuji Kasei Kogyo Co., Ltd.) 1.3% by weight and antioxidant (trade name: IRGANOX MD1024, manufactured by Ciba Specialty Chemicals Co., Ltd.) 2.4% by weight % And kneaded at 230 ° C. using a lab plast mill.
Table 6 shows the solidification start temperature Ts, solidification end temperature Tf, difference ΔT, φ20 × 13 mm injection-molded magnet (BH) max, ring-shaped magnet molding temperature, and surface properties of the obtained kneaded product.

[Conventional Example 3]
91.2% by weight of the surface-treated Sm—Fe—N-based magnetic powder obtained in Example 1 of the present invention and 5.1% by weight of nylon 12A (trade name: 3014U, manufactured by Ube Industries, Ltd.) Polymerized fatty acid-based polyamide (trade name: PA-30L, manufactured by Fuji Kasei Kogyo Co., Ltd.) 1.3% by weight and antioxidant (trade name: IRGANOX MD1024, manufactured by Ciba Specialty Chemicals Co., Ltd.) 2.4 % By weight and kneaded at 230 ° C. using a lab plast mill.
Table 6 shows the solidification start temperature Ts, solidification end temperature Tf, difference ΔT, φ20 × 13 mm injection-molded magnet (BH) max, ring-shaped magnet molding temperature, and surface properties of the obtained kneaded product.

As can be seen from Tables 1 to 7, in the examples, ΔT of the resin composition for bonding is 20 ° C. or higher, and when this composition is used, injection molding with good surface properties at a molding temperature of 220 to 270 ° C. A magnet was obtained. On the other hand, in the comparative example, ΔT of the resin composition for bonding is less than 20 ° C., and when this composition is used, it is short shot (the composition is not completely filled in the mold cavity) or filled. Roughness such as hot water wrinkles was seen on the surface of the molded body.
Further, even in the composition of the conventional example manufactured by referring to a known technique, the surface of the molded body remained rough because ΔT was less than 20 ° C. Note that some of the present examples such as Example 3 have a higher solidification end temperature Tf than the conventional example and the comparative example. It seems that those having a high Tf increase the melt viscosity of the composition at an early stage after injection and deteriorate the moldability compared with those having a low Tf, but this is not necessarily the case.
Although details are unknown, in the resin composition for bonding having the property that ΔT of the present invention is 20 ° C. or higher, the resin binder becomes supercooled at an extremely rapid cooling rate of injection molding, and melts even at temperatures below Tf. It is presumed that it is to keep the state.

(Example 25)
2 is a metal mold 1 having a core 3 having a diameter Dc of 20 mm and a cavity 2 having a diameter Do of 48 mm and a height H of 14 mm, and made of iron having an outer diameter Di, an inner diameter Dc of 20 mm, and a height H of 14 mm. The ring 4 is inserted, and the bonded magnet composition obtained in Example 7 is injection-molded from a one-point side gate into a space formed by these, thereby forming an outer periphery of 48 mm integrally formed with the iron ring 4 shown in FIG. A bonded magnet 10 having a height of 14 mm and a wall thickness (Do-Di) / 2 mm was manufactured. At this time, the mold temperature was set to 35 ° C., and the nozzle temperature was set to 245 ° C. The obtained 10 integrally formed bonded magnets did not crack even after 1 day at room temperature after molding. This was subsequently subjected to a heat cycle test to confirm the number of cracks. The heat cycle test conditions were set at 1 hour holding at 80 ° C. for 1 hour and 1 hour holding at −30 ° C. for 50 hours. The results are shown in Table 8. In addition, about the integrally molded magnet of Di = 43mm, the test was further continued and the number of cracks after performing the heat cycle up to 200 times was one.

(Example 26)
An integrally formed bonded magnet was produced in the same manner as in Example 25 except that the bonded magnet composition obtained in Example 10 was used. The obtained 10 integrally formed bonded magnets did not crack even after 1 day at room temperature after molding. This was followed by a heat cycle test. The results are shown in Table 9. In addition, about the integrally molded magnet of Di = 43mm, the test was further continued and the number of cracks after performing the heat cycle up to 200 times was two.

(Example 27)
An integrally formed bonded magnet was produced in the same manner as in Example 25 except that the inside of the cavity was reduced to −0.07 MPa through a mold air vent and injection molding was performed, and the heat cycle test was performed. The results are shown in Table 10. In addition, about the integrally molded magnet of Di = 43mm, the test was further continued and the number of cracks after performing the heat cycle up to 200 times was zero.

（実施例２８）
実施例２０で得られたボンド磁石用組成物を用いた以外は実施例２５と同様にして、一体成形ボンド磁石を製造した。得られた一体成形ボンド磁石１０個は、成形後常温で１日経過した後も割れなかった。これらを用いて引き続きヒートサイクル試験を行った。結果を表１１に示す。なお、Ｄｉ＝４３ｍｍの一体成形磁石については、さらに試験を継続し、ヒートサイクル回数を２００回まで行った後の割れ個数が１個だった。

(Example 28)
An integrally formed bonded magnet was produced in the same manner as in Example 25 except that the bonded magnet composition obtained in Example 20 was used. The obtained 10 integrally formed bonded magnets did not crack even after 1 day at room temperature after molding. A heat cycle test was subsequently conducted using these. The results are shown in Table 11. In addition, about the integrally molded magnet of Di = 43mm, the test was further continued and the number of cracks after performing the heat cycle up to 200 times was one.

(Comparative Example 18)
Using the bonded magnet composition obtained in Comparative Example 6, an integrally formed bonded magnet was produced in the same manner as in Example 25 except that the nozzle temperature was 280 ° C. The obtained bonded magnet surface was rough. For the integrally molded magnets with Di = 47, 46 and 43 mm, all 10 pieces were cracked within 1 hour at room temperature after injection molding. A heat cycle test was performed on an integrally molded magnet with Di = 38 mm. The results are shown in Table 12.

(Conventional example 4)
Using the bonded magnet composition obtained in Conventional Example 1, an integrally formed bonded magnet was produced in the same manner as in Example 25 except that the nozzle temperature was 280 ° C. The obtained bonded magnet surface was rough. Regarding the integrally molded magnet with Di = 47, 46 mm, all 10 pieces were cracked within 1 hour at room temperature after injection molding. A heat cycle test was performed on an integrally molded magnet with Di = 43 and 38 mm. The results are shown in Table 13.

  The bonded magnet obtained by molding the composition for bonded magnet of the present invention can be used in a wide range of fields including general household appliances, communication / acoustic equipment, medical equipment, and general industrial equipment, and its industrial value is extremely large.

It is a graph showing the temperature dependence of viscosity (eta) * of the composition for bonded magnets. It is a perspective view which shows the metal mold | die for integrally forming the composition for magnets with an iron ring, and manufacturing a cylindrical bond magnet. It is a perspective view which shows the cylindrical bond magnet which integrally formed the iron ring on the inner peripheral side. It is a perspective view which shows the cylindrical bond magnet which integrally formed the iron ring on the outer peripheral side.

Explanation of symbols

1 Mold 2 Cavity 3 Core 4 Steel ring 10 Bonded magnet

Claims (15)

In the bonded magnet composition in which the rare earth-transition metal magnetic powder (A) is mixed and dispersed in the resin binder (B),
The resin binder (B) comprises at least one resin binder (B) selected from a polymerized fatty acid-based polyamide block copolymer (B-1) or a polymerized fatty acid-based polyetheresteramide block copolymer (B-2). ) When the temperature of the composition for a bonded magnet in a molten state is lowered by containing 50% by weight or more of the whole, the temperature at which the rate of increase in viscosity of the composition starts to increase (solidification start temperature: Ts) The composition for a bonded magnet, wherein the difference ΔT from the temperature at which the rate of increase in viscosity begins to decrease (solidification end temperature: Tf) is 20 ° C. or higher.   The composition for a bonded magnet according to claim 1, wherein the magnetic powder (A) contains a rare earth (Nd or Sm) and a transition metal (Fe and / or Co).   The composition for bonded magnets according to claim 1, wherein the magnetic powder (A) has an average particle diameter of 1 to 100 μm.   The composition for bonded magnets according to claim 1, wherein the magnetic powder (A) further contains a ferrite magnetic powder. 2. The bonded magnet according to claim 1, wherein the polymerized fatty acid-based polyamide block copolymer (B-1) is a block copolymer having a skeleton represented by the following general formula (1) as a repeating unit. Composition.
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. M is an integer of 0 to 70, n is an integer of 1 to 150, and x is an integer of 1 to 100.) The polymerized fatty acid-based polyether ester amide block copolymer (B-2) comprises a polymerized fatty acid-based polyamide skeleton (a) having a skeleton represented by the following general formula (1) as a repeating unit and a general formula (2). The composition for bonded magnets according to claim 1, comprising the polyether ester amide skeleton (b) shown.
General formula (1)

(In the formula, R _{1 to} R ₄ , m, n, and x 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 (B-2), the copolymerization ratio (a) :( b) between the polymerized fatty acid-based polyamide skeleton (a) and the polyether ester skeleton (b) is 10:90. It is -90: 10, The composition for bonded magnets of Claim 1 characterized by the above-mentioned.   The polymerized fatty acid-based polyamide block copolymer (B-1) or the polymerized fatty acid-based polyetheresteramide block copolymer (B-2) has a number average molecular weight of 1,000 to 50,000. The composition for bonded magnets according to claim 1.   The polymerized fatty acid-based polyamide block copolymer (B-1) or the polymerized fatty acid-based polyetheresteramide block copolymer (B-2) has an acid value of 3 or less. A composition for bonded magnets.   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 a bonded magnet according to claim 1, wherein the resin binder (B) is contained in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the composition.   Solidification start temperature Ts is 170 degreeC or more, The composition for bonded magnets of Claim 1 characterized by the above-mentioned.   The bonded magnet formed by injection-molding the composition for bonded magnets in any one of Claims 1-12.   A bonded magnet formed by integrally molding the composition for bonded magnet according to any one of claims 1 to 12 with another metal material and / or an inorganic material component by any one of injection molding, compression molding or extrusion molding.   The bonded magnet according to claim 13 or 14, wherein the injection molding is performed at 265 ° C or lower.

Images