JPH10172820A - Composition for resin-bonded magnet and resin-bonded magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition of an excellent moldability and mechanical strength by comprising a composition of a mixture of a magnetic powder which is covered on its surface with a tiltanate-based coupling agent, having an anisotropic magnetic field of a specific value and a specific denatured polyamide resin. SOLUTION: Magnetic powder to be mixed is covered with a titanate-based coupling agent, having an anisotropic magnetic field of at least 50kOe. A denatured polyamide resin comprising denatured polyamide of a number average molecular weight of at most 10000 is mixed with a denatured polyamide resin of a number average molecular weight of at least 30000. The mixing ratio thereof is, based on 100 pts.wt. of magnetic powder, 2-48 pts.wt. of the denatured polyamide resin of a number average molecular weight of at most 1000 and 2-48 pts.wt. of the denatured polyamide resin of a number average molecular weight of at least 3000. The total mixing amount of the denatured polyamides is 4-50 pts.wt. Further an acidic organophosphorus compound is added in the ratio of 0.5-50 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a resin-bonded magnet, and more particularly to a composition for providing a resin-bonded magnet having excellent moldability (melt fluidity) and mechanical strength. Related to the magnet used.

[0002]

2. Description of the Related Art Permanent magnets such as ferrite magnets, alnico magnets, and rare earth magnets are used in various applications including motors. However, since these magnets are mainly produced by a sintering method, they are generally brittle, and it is difficult to obtain thin magnets or complicated shapes. Also, shrinkage during sintering is 15-20.
%, High dimensional accuracy cannot be obtained, and post-processing such as polishing is required to increase the accuracy.

[0003] The resin-bonded magnet solves these drawbacks and opens up new applications, and is made by using a thermoplastic resin such as nylon as a binder and filling it with magnetic powder. However, resin magnets using a thermoplastic resin as a binder, when filled with magnetic powder at 80% by weight or more, the viscosity at the time of melt molding rapidly increases and molding becomes difficult. Molding is performed by adding a lubricant for thermoplastic resins such as stearic acid-based metal soap and paraffin, but there is a limit. Further, as the filling amount of the magnetic powder increases, the mechanical strength decreases.

[0004]

In recent years, small motors,
Resin-bonded magnets used for audio equipment, OA equipment, etc.
Due to the demand for miniaturization of devices, there is a demand for magnetic devices having high magnetic properties, excellent dimensional accuracy, and low cost. However, the moldability (melt flow property) and mechanical strength of the conventional resin-bonded magnet composition obtained only with the magnetic powder, polyamide resin and lubricant are not always sufficient for use in the above-mentioned applications. Early improvement of the composition for mold magnets has been desired.

Accordingly, the present invention has been made to solve the drawbacks of the conventional polyamide resin-bonded magnet composition, and to provide a magnet composition having excellent moldability (particularly, melt fluidity) and mechanical strength. Aim.

[0006]

Means for Solving the Problems In order to achieve the above object, the present inventors conducted various studies by changing the types and amounts of polyamide resin and additives, and as a result, found that magnetic powder and modified polyamide were In this mixture, the magnetic powder is coated with a titanate-based coupling agent, and the surface thereof is coated with a magnetic powder having an anisotropic magnetic field ( _HA ) of 50 kOe or more, and the modified polyamide has a terminal group modified with a monocarboxy group hydrocarbon. It is a mixture of a terminal group-modified polyamide resin having a number average molecular weight of 10,000 or less and a terminal group-modified polyamide resin having a number average molecular weight of 30,000 or more, and has excellent moldability (melt fluidity) by further adding an acidic organic phosphorus compound. It has been found that a composition for a resin-bound magnet having mechanical strength can be obtained. It is a mixture of a terminal group-modified polyamide oligomer having a number average molecular weight of 1,000 or less and a terminal group modified polyamide resin having a number average molecular weight of 10,000 or more, the terminal group of which has been modified with hydrogen chloride, and which is excellent by further adding an acidic organic phosphorus compound. It has been found that a resin-bonded magnet composition having improved moldability (melt fluidity) and mechanical strength can be obtained, and the present invention has been completed.

That is, the present invention is a composition in which an acidic organic phosphorus compound is added to a mixture comprising a magnetic powder and a modified polyamide, wherein the magnetic powder has a surface coated with a titanate coupling agent. Anisotropic magnetic field ( _HA ) 5
0 kOe or more of magnetic powder, the modified polyamide is a mixture of a terminal group-modified polyamide resin having a number average molecular weight of 10,000 or less and a terminal group modified with a monocarboxyl group hydrocarbon and a number average molecular weight of 30,000 or more. A composition for a resin-bonded magnet, characterized by that
The mixing ratio of the modified polyamide resin having a number average molecular weight of 10,000 or less with respect to 100 parts by weight of the magnetic powder is 2 parts by weight.
To 48 parts by weight, the mixing ratio of the modified polyamide resin having a number average molecular weight of 30,000 or more is 2 to 48 parts by weight, the total of the two types of modified polyamides having a number average molecular weight of 4 to 50 parts by weight, the acidic organic phosphorus compound 0.5 to 50
It is a composition for a resin-bonded magnet, which is in parts by weight.

The present invention also relates to a composition comprising a mixture of a magnetic powder and a modified polyamide to which an acidic organic phosphorus compound is added, wherein the magnetic powder has a surface coated with a titanate coupling agent. Anisotropic magnetic field ( _HA ) 50k
Oe or more magnetic powder, the modified polyamide has a number average molecular weight of 10 whose terminal group is modified by a monocarboxyl hydrocarbon.
A resin-bonded magnet composition characterized by being a mixture of a terminal group-modified polyamide oligomer having a number average molecular weight of 10,000 or more and a terminal group-modified polyamide resin having a number average molecular weight of 10,000 or more,
And, assuming that the magnetic powder is 100 parts by weight, the mixing ratio of the modified polyamide oligomer having a number average molecular weight of 1,000 or less is 2 to 48 parts by weight, the mixing ratio of the modified polyamide resin having a number average molecular weight of 10,000 or more is 2 to 48 parts by weight, A resin-bonded magnet composition, wherein the total of the modified polyamide is 4 to 50 parts by weight, and the mixing ratio of the acidic organic phosphorus-based compound is 0.5 to 50 parts by weight.

Further, there is provided a resin-bonded magnet obtained by subjecting these resin-bonded magnet compositions to heat molding.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The magnetic powder used in the present invention includes an anisotropic magnetic field ( _HA ).
However, if it is a magnetic powder of 50 kOe or more, a magnetic powder usually used for a resin-bonded magnet can be used.
mCo ₅ system, Sm ₂ (Co, Fe, Zr, V) ₁₇ system, Sm
₂ (Co, Cu, Fe, Zr) ₁₇ type, Sm ₂ (Co, C
u, Fe, Zr, Te) ₁₇ based, Sm ₂ (Co, Cu, F)
e, Ta, Te) rare earth cobalt-based such as ₁₇ -based, Nd-F
e-Co-B system, Nd-Dy-Fe-B system, Nd-Fe
Rare earths such as B-based iron-boron-based, Sm-Fe-N-based,
Sm-Fe-Co-N system, Nd-Fe-Ti-N system, N
Rare earth-iron-nitrogen-based magnetic powders such as d-Fe-VN-based powders.

The present inventors have found that in the above-mentioned resin-bonded magnet composition, when the alloy powder obtained by the Sm—Co ₅ based reduction diffusion method or the Sm—Fe—N based alloy powder exemplified above is used as the magnetic powder. For example, it has been confirmed that a resin-filled magnet having a high filling of, for example, 93% by weight or more and having excellent magnetic properties can be obtained. The Sm-Co ₅ magnetic powder obtained by the reduction diffusion method is preferably pulverized by a jet mill, a ball mill or the like. The preferred particle size of these magnetic powders is 7 μm or less on average, and particularly preferably 5 μm or less on average.

The magnetic powder must be coated with a titanium-based surface treating agent, ie, a coupling agent, in an amount of 0.1 to 3.0 parts by weight based on 100 parts by weight of the magnetic powder. It is. Examples of these coupling agents include isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl Representative examples include trioctanoyl titanate, isopropyl dimethacryl isostearyl titanate, and isopropyl tridecylbenzenesulfonyl titanate.

When these magnetic powders not coated with a titanium-based surface treating agent are used, the reaction with the acidic organic phosphorus-based compound proceeds rapidly during heat-kneading or heat-molding, so that not only the magnetic properties are remarkably deteriorated but also ignition occurs. It cannot be used because of danger.

In the composition, the modified polyamide, which is an essential component, functions as a binder for magnetic powder. The modified polyamide used in the present invention includes a monocarboxyl hydrocarbon and a terminal group having a terminal group. A mixture of a modified modified polyamide resin having a number average molecular weight of 10,000 or less and a modified polyamide resin having a number average molecular weight of 30,000 or more, or a modified polyamide oligomer having a number average molecular weight of 1,000 or less whose terminal group is modified by a monocarboxyl group hydrocarbon It is characterized by comprising a mixture with a modified polyamide resin having an average molecular weight of 10,000 or more. As long as this condition is satisfied,
6 nylon, 6-6 nylon, 11 nylon, 12 nylon, 6-12 copolymer nylon, aromatic nylon, etc.
Mixing with these homopolymers, copolymers with other kinds of monomers, products with terminal group treatment with other substances, etc. may be used, but nylon 11 or nylon 12 is preferable in consideration of moldability.

In the first and second resin-bonded magnet compositions of the present invention, the modified polyamide has a number average molecular weight of 10,000 or less and a modified polyamide resin having a number average molecular weight of 30,000 or more. The mixing ratio is 2 to 48 parts by weight as a modified polyamide resin having a number average molecular weight of 10000 or less and 2 to 48 parts by weight as a modified polyamide resin having a number average molecular weight of 30000 or more, based on 100 parts by weight of the magnet powder. Preferably, there is. Deviating from this mixing ratio, the number average molecular weight is 10
If the modified polyamide resin having a number average molecular weight of 30,000 or more exceeds 48 parts by weight, the mechanical strength of the molded product increases, but the moldability (melt fluidity) decreases. Therefore, it is not preferable. When the modified polyamide resin having a number average molecular weight of 10,000 or less exceeds 48 parts by weight, and when the modified polyamide resin having a number average molecular weight of 30,000 or more is less than 2 parts by weight, the moldability (melt fluidity) is improved, but the mechanical strength is poor. It is not preferable because it decreases.

In the third and fourth compositions for resin-bonded magnets of the present invention, the modified polyamide has a molecular weight of a modified polyamide oligomer having a number average molecular weight of 1,000 or less and a modified polyamide resin having a number average molecular weight of 10,000 or more. Characterized in that the mixing ratio is such that the number average molecular weight is 1000
It is preferable that the modified polyamide oligomer is 2 to 48 parts by weight as the following modified polyamide oligomer and 2 to 48 parts by weight as the modified polyamide resin having a number average molecular weight of 10,000 or more. Deviating from this mixing ratio, the modified polyamide oligomer having a number average molecular weight of 1,000 or less is less than 2 parts by weight, and the number average molecular weight is 1,000.
When the amount of the modified polyamide resin of 0 or more exceeds 48 parts by weight, the mechanical strength of the molded article is increased, but the moldability (melt fluidity) is undesirably reduced. Number average molecular weight 1
If the modified polyamide oligomer having a number average molecular weight of 10,000 or more is less than 2 parts by weight, the moldability (melt fluidity) is improved, but the mechanical strength is reduced. Therefore, it is not preferable.

On the other hand, if the total amount of the modified polyamide is less than 4 parts by weight with respect to 100 parts by weight of the magnetic powder, the kneading torque and fluidity are remarkably reduced, and molding becomes difficult. If the amount is more than 50 parts by weight, desired magnetic properties cannot be obtained. Therefore, the filling amount of the terminal group-modified polyamide resin is preferably 4 to 50 parts by weight.

The shape of these polyamide resins is
The powder, beads, pellets and the like are not particularly limited, but powder is preferred from the viewpoint of uniform mixing with the magnetic powder.

The monocarboxyl group hydrocarbon used for modifying the terminal group used in the present invention includes, for example, pentanoic acid, heptanoic acid, octanoic acid, decanoic acid, dodecanoic acid,
Octadecanoic acid, benzoic acid and the like can be mentioned. As a method for modifying the terminal group of the polyamide resin, a method of adding these monocarboxyl hydrocarbons during polymerization of the polyamide resin or a method of mixing and reacting the polyamide resin and these monocarboxyl hydrocarbons in a closed heating solution There is.

The acidic organic phosphorus compound of the present invention includes, for example,
Methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, 2-
Examples include ethylhexyl acid phosphate, di-2-ethylhexyl phosphate, isodecyl acid phosphate, and monoisodecyl acid phosphate.

These compounds are added at a ratio of 0.5 to 50 parts by weight based on 100 parts by weight of the magnetic powder, preferably 1.0 to 20 parts by weight, more preferably 1.0 to 20 parts by weight.
To 10 parts by weight. The compound may be mixed simultaneously with the magnetic powder and the modified polyamide. When the amount of the compound is less than 0.5 part by weight based on 100 parts by weight of the magnetic powder,
Moldability is reduced, and as a result, the content of magnetic powder cannot be increased, so that a magnet having high magnetic properties cannot be obtained. If the amount exceeds 50 parts by weight, desired physical properties (particularly, mechanical strength) cannot be obtained.

In the composition of the present invention, a lubricant for plastic molding, various stabilizers and the like can be added in addition to the above-mentioned components.

Examples of the lubricant include waxes such as paraffin wax, liquid paraffin, polyethylene wax, polypropylene wax, ester wax, carnauba, and micro wax, stearic acid, 1,2-
Fatty acids such as oxystearic acid, lauric acid, palmitic acid and oleic acid, calcium stearate, barium stearate, magnesium stearate, lithium stearate, zinc stearate, aluminum stearate, calcium laurate, zinc linoleate, calcium ricinoleate Fatty acid salts (metal soaps) such as zinc, 2-ethylhexoate and the like, stearamide, oleamide, erucamide, behenamide, palmitamide, lauric amide, ethylenebisstearic amide, ethylenebislauric acid Fatty acid amides such as amides, distearyl adipamides, ethylene bisoleic acid amides, dioleyl adipamides, N-stearyl stearamides, and fatty acid esters such as butyl stearate Le, ethylene glycol, alcohols such as stearyl alcohol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and polyethers consisting modification thereof,
Examples include fluorine compound such as fluorine-based oil, fluorine-based grease, and fluorine-containing resin powder, and inorganic compound powder such as silicon nitride, silicon carbide, magnesium oxide, alumina, silicon dioxide, and molybdenum disulfide.

As the stabilizer, bis (2,2,2)
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-succinate (2-
(Hydroxyethyl) -4-hydroxy-2,2,6,6
-Tetramethylpiperidine polycondensate, poly [ポ リ 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) Hindered amine based stabilizers such as bis (1,2,2,6,6-pentamethyl-4-piperidyl) -2-hydroxybenzyl) -2-n-butylmalonate, as well as phenol based, phosphite based and thioether based stabilizers And the like.

In the present invention, the mixing method of each component is not particularly limited. For example, a mixing machine such as a ribbon blender, a tumbler, a Nauter mixer, a Henschel mixer, a super mixer, or a Banbury mixer, a kneader, a roll, a kneader ruder, a single mixer, etc. It is carried out using a kneader such as a screw extruder or a twin screw extruder.

The composition of the present invention can be obtained in the form of powder, beads, pellets or a mixture thereof by mixing the respective components, but pellets are preferable in terms of easy handling. The obtained composition is molded by various thermoplastic resin molding machines, preferably an injection molding machine and an extrusion molding machine.

[0027]

The present invention will be described more specifically with reference to the following examples and comparative examples. The details, test methods, and evaluations of each component used in the examples and comparative examples are illustrated, but are not limited thereto without departing from the gist of the present invention.

A composition and a magnet for a resin-bonded magnet were manufactured and evaluated by the following materials and methods. The materials used are shown below.

The end group-modified polyamide resin is obtained by adding a desired stearic acid to commercially available 12 nylon, mixing and reacting at 300 ° C. in a nitrogen atmosphere under a pressure of 1 kg / cm ² for 3 hours, and performing gel permeation. It was used after confirming the molecular weight in terms of polystyrene resin by a chromatographic method.

A Magnetic powder ・ Magnetic powder 1: SmCo ₅ magnetic powder (trade name: RCo ₅ alloy, manufactured by Sumitomo Metal Mining Co., Ltd.) Anisotropic magnetic field: 246 kOe ・ Magnetic powder 2: Nd—Fe—B magnetic powder ( (Product name: MQP-B, manufactured by General Motors, Inc.) Anisotropic magnetic field: 70.4 kOe

B: Terminal group-modified polyamide oligomer and resin (terminal group-modified polylaurolactam) PA1: terminal group-modified 12 nylon (number average molecular weight: Mn = 500) PA 2: terminal group-modified 12 nylon (number average molecular weight) PA 3: end-group modified 12 nylon (number-average molecular weight: PA-Mn = 1100) PA 4: end-group modified 12 nylon (number-average molecular weight: PA-Mn = 5000) PA 5: terminal-group modified 12 nylon (Number-average molecular weight D-Mn = 9500) PA 6: Terminal group-modified 12 nylon (Number-average molecular weight D-Mn = 11000) PA 7: Terminal group-modified 12 nylon (Number-average molecular weight D-Mn = 18,000) PA 8: Terminal Group-modified 12 nylon (number-average molecular weight PA-Mn = 31500) PA 9: Terminal-group-modified 12 nylon ( (Number-average molecular weight, P-Mn = 35,000)

C. Acidic organic phosphorus compound. Compound 1 (trade name: MP-4, manufactured by Daihachi Chemical Industry Co., Ltd.) Compound 2 (trade name: AP-1, manufactured by Daihachi Chemical Industry Co., Ltd.)

Next, the manufacturing method and evaluation method of each molded product will be described as follows. Mixing and Preparation of I Composition A predetermined resin and each additive system are added to each magnetic powder in a predetermined ratio (each part by weight), and thoroughly mixed and stirred in a planetary mixer (40 rpm, 80 ° C.). ) And then dried in a vacuum oven at 120 ° C for 24 hours. The mixture obtained by these was used as a 20 mmφ single extruder (L / D = 25, CR = 2.0, rotation speed = 20r)
pm, 5mmφ strand die, cylinder temperature 200
To 280 ° C., a die temperature of 280 ° C.), and a 5 mmφ × 5 mm pellet compound for a resin-bonded magnet was prepared using a hot cut pelletizer.

II Method for Evaluating Melt Fluidity Fluidity (MFR) Evaluation The pellet-like composition obtained under the above kneading conditions was subjected to a Koka type flow tester manufactured by Shimadzu Corporation (temperature: 250).
° C, Load: 30kgf, Die shape: 1mmφ × 1m
m, preheating: 120 seconds) The fluidity was measured.

The results are shown in Tables 1 and 2. It has been found in the fluidity evaluation that if a fluidity of 1.5 g / min or more can be ensured, no problems will be caused in molding.

III Evaluation of mechanical strength (three-point bending strength) These pellet compounds were subjected to a magnetic field injection molding machine (J-20MII) manufactured by Nippon Steel Works Co., Ltd. (5 mm in width × 15 in length).
The same conditions are used for the test resin-bonded magnet of 2 mm x 2 mm (molding temperature 240-290 ° C, mold temperature 100-120 ° C).
The bending strength of these magnet molded products obtained was determined at room temperature at a head speed of 2 mm / min using an autograph manufactured by Shimadzu Corporation. The results are similarly shown in Tables 1 and 2. The bending strength is 5.0 kgf / mm ²
It is known that if the above is satisfied, the mechanical strength is sufficient.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

[Table 5]

[0042]

As described above, the resin composition for a resin-bonded magnet of the present invention has improved moldability and mechanical strength as compared with the prior art, and is required for high-performance products, such as general home appliances, It is particularly useful in a wide range of fields, such as communication and audio equipment, medical equipment, and general industrial equipment.

Claims (5)

[Claims] 1. A composition comprising a mixture of a magnetic powder and a modified polyamide to which an acidic organic phosphorus compound is added, wherein the magnetic powder has an anisotropic magnetic field whose surface is coated with a titanate coupling agent. H _A ) a magnetic powder of 50 kOe or more, and the modified polyamide is a terminal group-modified polyamide resin having a terminal group modified with a monocarboxyl group hydrocarbon and having a number average molecular weight of 10,000 or less and a number average molecular weight of 30,000
A composition for a resin-bonded magnet, which is a mixture with the above terminal group-modified polyamide resin. 2. The modified polyamide resin having a number average molecular weight of 10,000 or less based on 100 parts by weight of the magnetic powder, a modified polyamide resin and an acidic organic phosphorus compound based on 100 parts by weight of the magnetic powder, modified polyamide, and 2 to 48 parts by weight of a number average molecular weight. The modified polyamide resin of 30,000 or more is 2 to 48 parts by weight, the total of the two kinds of modified polyamides is 4 to 50 parts by weight, and the acidic organic phosphorus compound is 0.5 to 50 parts by weight. The composition for a resin-bonded magnet according to claim 1. 3. A composition comprising a mixture of a magnetic powder and a modified polyamide to which an acidic organic phosphorus compound is added, wherein the magnetic powder has an anisotropic magnetic field whose surface is coated with a titanate coupling agent. H _A ) a magnetic powder of 50 kOe or more, and the modified polyamide is a terminal group-modified polyamide oligomer having a terminal group modified with a monocarboxyl hydrocarbon and having a number average molecular weight of 1,000 or less, and a number average molecular weight of 100
A resin-bonded magnet composition, which is a mixture with a terminal group-modified polyamide resin of 00 or more. 4. A mixing ratio of a magnetic powder, a modified polyamide and an acidic organophosphorus compound, wherein 100 parts by weight of the magnetic powder and 2 to 48 parts by weight of the modified polyamide oligomer having a number average molecular weight of 1,000 or less, The modified polyamide resin of 10,000 or more is 2 to 48 parts by weight, the total of the two kinds of modified polyamides is 4 to 50 parts by weight, and the acidic organic phosphorus compound is 0.5 to 50 parts by weight. The composition for a resin-bonded magnet according to claim 3. 5. A resin-bonded magnet obtained by heat-forming the composition for a resin-bonded magnet according to any one of claims 1 to 4.