JPH03188601A - Nb-fe-b plastic magnet composition - Google Patents

Abstract

PURPOSE:To obtain a plastic magnet composition stable under high-temperature high-humidity by adding Nb-Fe-B magnetic powder surface-treated with a polyorganosiloxane resin having at least one silanol group and a molecular weight of 10<3> or more and an organic binder. CONSTITUTION:An organic binder A is not limited, and an epoxy resin, etc., are used. Nb-Fe-B magnetic powder B has particle size of 500mum or less, and is surface-treated with polyorganosiloxane acquired by polycondensing silanol (R represents an alkyl group or an aryl group and (n) represents 1 or 2 and may be the same when (n) is two) shown in formula RnSi(OH)4-n. A substance containing 40mol% silanol in n=1 in formula is particularly effective, and is used in approximately 0.5-20 pts.wt. per 100 pts.wt. powder. Surface treatment is conducted in such a manner that polyorganosiloxane having a molecular weight of 10<3> or more is added to a proper solvent, brought into contact with powder B and dried and cured. The binder A and the magnetic powder B are employed within a range of 1/99-10/90. A plastic magnet, which is difficult to be oxidized and has stable magnetic characteristics and excellent moldability, is acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel Nd-Fe-B plastic magnet composition, and more particularly, to a novel Nd-Fe-B plastic magnet composition, which is extremely resistant to oxidation and stable even in harsh environments of high temperature and high humidity. The present invention relates to a Nd-Fe-B plastic magnet composition that can provide a plastic magnet with magnetic properties.

Conventional technology In recent years, plastic magnets have sufficiently retained the magnetic properties of conventional isotropic sintered ferrite magnets, and also have good moldability, high heat distortion temperature, high impact strength, and light weight. Because of its advantages such as , it has attracted attention as a highly functional material, and is used for applications such as motors, timers, switches, relays, communication equipment, audio equipment, electronic and electrical equipment, automobiles, medical treatment fields, etc. is expected.

Such plastic magnets are usually produced by compression molding, injection molding, or compression molding or injection molding. It is manufactured by molding into a desired shape using a method such as extrusion molding. The magnetic powders are mainly classified into ferrite-based and rare-earth-based magnetic powders, and glass magnets using rare-earth magnetic powders are currently attracting attention because they have excellent magnetic properties.

However, the rare-earth magnetic powder, especially the Nd-Fe-B magnetic permeable powder, which has attracted attention for its excellent magnetic properties, is extremely easily oxidized, and this tendency becomes more pronounced as the particle size becomes smaller. Diameter is 50I1m
The following materials are easily oxidized by heating when mixed with resin or by moisture in the air, resulting in deterioration of magnetic properties and also having the disadvantage that the surface is susceptible to rust even after plastic magnets are made. ing.

Therefore, in order to improve such defects, for example, a method of surface treating Nd-Fe-B magnetically permeable powder with a phosphorus compound (Japanese Unexamined Patent Publication No. 60-240105), a method of treating the surface of Nd-Fe-B magnetically permeable powder with a phosphorus compound, A method has been proposed in which a surface is compositely coated with a silane-based organometallic compound and a titanate-based organometallic compound having a functional group that easily reacts with an inorganic substance (Japanese Patent Laid-Open No. 1-161803). However, although these methods can suppress oxidation to a certain extent, they are not necessarily satisfactory, as their oxidation prevention effect is insufficient in harsh environments of high temperature and high humidity, and they require a large number of processing steps. do not have.

Problems to be Solved by the Invention Under these circumstances, the present invention has been made to provide a plastic magnet that does not oxidize and has stable magnetic properties even in harsh environments of high temperature and high humidity. It was made for the purpose of providing a B-based plastic magnet composition.
It's a small thing.

Means for Solving the Problems The present inventors developed Nd-Fe having the above-mentioned preferable properties.
- As a result of intensive research to develop a B-based plastic magnet composition, we have found that Nd-Fe-B magnetic powder is surface-treated with a polyorganosiloxane resin with a molecular weight of 103 or more and has at least one silanol group. It was discovered that the purpose could be achieved by using powder, and the present invention was completed based on this knowledge.

That is, the present invention provides (A) an organic binder and (B) N
d-Fe-B magnetic permeable powder, the Nd-Fe-B magnetic powder comprises:
The present invention provides an Nd-Fe-B plastic magnet composition, which is surface-treated with a polyorganosiloxane resin having a molecular weight of 103 or more and having at least one silanol group.

The present invention will be explained in detail below.

There are no particular restrictions on the organic binder as component (A) in the composition of the present invention, and those conventionally used in plastic magnets can be used.

Examples of such materials include thermosetting resins such as epoxy resins and polyurethane, and thermoplastic resins such as polyethylene and polyvinyl chloride polyamide. These organic binders may be used alone or in combination of two or more.

In the composition of the present invention, the magnetic powder of component (B) has a molecular weight of 10 and has at least one silanol group.
Nd-Fe-B magnetically permeable powder surface-treated with three or more polyorganosiloxane resins is used. The Nd
-Fe-B magnetic powder is not particularly limited, and any known magnetic powder used in plastic magnets can be used.

Further, as the Nd-Fe-B magnetic powder, one having a particle size of usually 500 μm or less is used.

The polyorganosiloxane used for the surface treatment of this Nd-Fe-B magnetically permeable powder has the general formula % () (where R is an alkyl group or an aryl group, and n is 1 or 2
, and when R is 2, these may be the same or different). can. Particularly preferred is a polyorganosiloxane resin containing 40 mol % or more of the resin in which n in the above general formula is 1.

These polyorganosiloxane resins may be used alone or in combination of two or more, and
The amount used is usually selected within the range of 0.5 to 20 parts by weight per 100 parts by weight of Nd-Fe-B magnetic powder. If this amount is less than 0.5 parts by weight, the antioxidant effect will not be sufficiently exhibited, and if it exceeds 20 parts by weight, the coating layer coated on the surface of the magnetic particles will become too thick and the magnetic properties will tend to deteriorate. Be looked at.

For surface treatment of the Nd-Fe-B magnetic powder, for example, a polyorganosiloxane resin having a molecular weight of 103 or more and having at least one silanol group is added to an appropriate solvent to prepare a surface treatment solution with an appropriate concentration. , the Nd-Fe-
This can be done by bringing the B-based magnetic powder into contact with the solution and then drying and curing it.

At this time, other surface treatment agents such as known silane coupling agents and titanate coupling agents may be added to the surface treatment liquid as desired.

Further, in the present invention, the surface of the Nd-Fe-B magnetic powder is bonded to the polyorganosiloxane resin having at least one silanol group and having a molecular weight of 103 or more and a silane coupling agent used as desired. Multi-stage treatment may be performed using a titanate coupling agent or a titanate coupling agent.

Examples of the silane coupling agent used as desired include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane, and γ-methacryloxysilane. Propyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-1-aminopropyltrimethoxysilane, Examples include methoxysilane, γ-ureidopropyltriethoxysilane, and N-β-(aminoethyl)-7-aminopropylmethyldimethoxysilane.

Further, titanate coupling agents that can be used as desired include, for example, isopropyl triisostearoyl titanate, tetraoctyl bis(ditridecyl phosphite) titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, Examples include pyrophosphate) ethylene titanate.

In the composition of the present invention, the weight ratio of the organic binder (A) and the magnetic powder (B) is usually 1
:99 to 10:90, taking into consideration the molding method. This is because if the weight ratio of the magnetic powder of component (B) exceeds 99, good mechanical properties such as moldability, impact strength, and tensile strength, which are characteristics of plastic magnets, will be lost. If the weight ratio of the magnetic powder is less than 90, the magnetic properties will deteriorate, and the superiority of the magnet will be lost compared to other low-cost magnets such as ferrite and alnico magnets. Further, the composition can be prepared, for example, by melt-kneading the organic binder as the component (A), the magnetic powder as the component (B), and various additives used as desired in predetermined proportions. I can do it. There are no particular restrictions on the kneading device, and for example, a Henschel mixer, a single-screw or twin-screw extruder, a Banbury mixer, a roll, etc. can be used.

Examples of the various additives used as desired include lubricants, colorants, stabilizers, antioxidants, ultraviolet absorbers, and plasticizers.

The Nd-Fe-B plastic magnet composition of the present invention prepared in this way can be processed by, for example, compression molding, injection molding,
By molding into a desired shape by extrusion molding or the like, it is possible to provide an Nd-Fe-B plastic magnet that is extremely resistant to oxidation, has stable magnetic properties, and has good moldability.

In the present invention, the molded article obtained in this way is further provided with at least one silanol group having a molecular weight of 10.
By treating with three or more polyorganosiloxane resins, the effect can be further enhanced.

Effects of the Invention According to the present invention, by using Nd-Fe-B-based magnetic powder surface-treated with a specific polyorganosiloxane resin as the magnetic powder, it is extremely resistant to oxidation even in harsh environments of high temperature and high humidity. A Nd-Fe-B plastic magnet composition that can provide a plastic magnet with stable magnetic properties and excellent adhesion between an organic binder and magnetic powder can be easily obtained.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

Example 1 CHsSi(OH)s 88 mol% and (CHs)zsi
A 20% by weight toluene solution of polyorganosiloxane resin with a molecular weight of 10' to 1O6 obtained by polycondensation of a mixture consisting of 12 mol% of (OH)z is diluted with 100 parts by weight of toluene, and this diluted solution and Nd-Fe-B magnetic powder MQP-B (manufactured by GM, content of 0.1% by weight or less for particles with a particle size of 40 mesh or more, content of 151% by weight or less for particles with a particle size of 325 mesh or less), The active ingredients in the diluted solution were mixed at a ratio of 2% by weight based on MOP-B, stirred for 5 minutes, filtered off the magnetic powder, and dried and hardened at room temperature with constant vibration. A surface-treated Nd-Fe-B magnetic powder was obtained.

Next, for the magnetic powder surface-treated in this way,
- Molded epoxy resin XNR-4203 (Nagase Ciba Co., Ltd.)
After preparing a composition by blending 3 wt. A plastic magnet was produced by curing in an atmosphere at 120°C for 2 hours.

The magnetic properties of this plastic magnet were determined when it was stored at room temperature for 24 hours, when it was stored at 250°C for 20 minutes (high temperature condition), and when it was stored at 60°C and 195% RH atmosphere for 25 hours (high temperature condition). Measurements were made under three conditions. The results are shown in Table 1.

In the table, Br is the residual magnetic flux density, 4πIs is the saturation magnetization, iHc is the coercive force, (BH)max is the maximum energy product, and SQ is the squareness ratio, which was calculated according to the following formula.

Table 2 also shows the value of (BH)max at room temperature as 100
The ratio of (BH)max under high temperature and high humidity conditions is shown.

Example 2 As polyorganosiloxane resin, R51(OH)
Obtained by polycondensing a mixture consisting of 73 mol% of s and 27 mol% of JSi(OH)z (R is a mixture of methyl and phenyl groups, the molar ratio is 1.2:l) A toluene solution having an active ingredient amount of 2% by weight was prepared in the same manner as in Example 1 using a polyorganosiloxane resin having a molecular weight of 103 to 10'. Next 1. A plastic magnet was produced in the same manner as in Example 1, except that the surface was treated with N and then dried at 60° C., and its magnetic properties were determined. The results are shown in Tables 1 and 2.

Comparative Example 1 A plastic magnet was produced in the same manner as in Example 1 except that a methanol solution of phosphoric acid was used instead of the polyorganosiloxane resin.1. Its magnetic properties were determined. The results are shown in Tables 1 and 2.

Comparative Example 2 A plastic magnet was produced in the same manner as in Example 1, except that a hexane diluted solution of isopropyl triisostearoyl titanate was used instead of the polyorganosiloxane resin, and its magnetic properties were determined. Ta.

The results are shown in Tables 1 and 2.

Table 1 Table 2 Tables 1 and 2 show that Nd-Fe-B magnetic powder treated with polyorganosiloxane resin having a molecular weight of 10' or more and having at least one silanol group is It can be seen that even after storage in a humid environment, the deterioration of magnetic properties is extremely small compared to those treated with conventional phosphoric acid or titanate coupling agents.

Claims (1)

[Claims] 1. In a plastic magnet composition comprising (A) an organic binder and (B) an Nd-Fe-B magnetic powder, the Nd-Fe-B magnetic powder has a molecular weight of at least one silanol group. An Nd-Fe-B plastic magnet composition, characterized in that it is surface-treated with a polyorganosiloxane resin of 10^3 or more.