JPH057428B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a composition for a synthetic resin magnet, and more specifically, a maximum energy product (hereinafter referred to as BHmax) that is significantly larger than that of conventional synthetic resin magnets. ). "Prior Art and Problems" BHmax is a measure that expresses the magnetic performance of a magnet, but the synthetic resin magnets proposed so far have a BHmax of at most 1.7 megagauss Oersteds (hereinafter referred to as MGOe). ) can only be obtained. Generally, BHmax is controlled by the content of magnetic powder in the synthetic resin magnet. That is, it is known that the higher the magnetic powder content, the higher the magnetic powder content. However,
In general, when the magnetic powder content is increased, the fluidity during heat molding deteriorates, and molding becomes impossible, or even if molding is possible, the degree of orientation (the value obtained by dividing the residual magnetic flux density by the saturation magnetic flux density) due to the application of a magnetic field becomes extremely As a result, BHmax conversely decreases. Therefore, so far we have obtained
The reality is that BHmax remains at most around 1.7MGOe. Therefore, its practical use is extremely limited and narrow. ``Means for solving the problem'' In view of the above circumstances, the present inventors conducted intensive research and found that by adding a specific compound, BHmax was
The present invention was completed by discovering that an amazingly large BHmax of 2.1 MGOe, which far exceeds 1.7 MGOe, can be obtained. That is, the present invention provides a magnetoplumbite type ferrite powder and a formula (In the formula, R ₁ is an alkyl group or an alkoxy group having 4 to 20 carbon atoms, and R ₂ , R ₃ , and R ₄ are a mixture of an alkoxy group and an alkyl group containing 1 to 3 alkoxy groups having 1 to 3 carbon atoms. ) A synthetic resin magnet composition comprising the substance represented by the following formula and a synthetic resin as basic components is cooled and solidified under heating and melting conditions while applying a magnetic field. The magnetoplumbite type ferrite powder used in the present invention is MO・nFe ₂ O ₃ (M is Ba,
A powder having a composition of Sr (where n is 4.5 to 6.5) is preferably selected. The blending ratio in the composition of the present invention is
In order to make BHmax 1.8MGOe or more, 60 volume percent or more is required. However, if it exceeds 94 volume percent, the melt fluidity is extremely reduced, making it difficult to mold, or even if molding is possible, the degree of orientation tends to decrease. Therefore, the blending amount of ferrite powder is 60
~94 volume percent is preferred. By the way, if the specific substance of the present invention is not added, if the amount of ferrite powder exceeds 60 volume percent, the fluidity will be poor and it will not be possible to mold it, or even if it can be molded, a significant decrease in the degree of orientation will be observed, and the target will not be met. It is not possible to obtain the BHmax value. The specific substance used in the present invention has the formula where R ₁ is a carbon number of 8 to
20 alkyl or alkoxy groups, R ₂ , R ₃ , R ₄
is characterized by being a mixture of an alkoxy group and an alkyl group containing 1 to 3 alkoxy groups having 1 to 3 carbon atoms, and these are used alone or in a mixture, and the blending amount is 0.1 to 2% by volume. Appropriate.
If it is less than 0.1 volume percent, the fluidity of the mixture during melting will be extremely poor and sufficient effects will not be exhibited. Moreover, even if it exceeds 2 volume percent, the increase in effectiveness is extremely small and is meaningless in terms of cost. The method of adding the above-mentioned specific substance is not particularly limited, but if anything, the effect can be expected with a smaller amount of addition if it is applied to the ferrite powder in advance. As for the coating method, the substance may be added as it is, or it may be added after being diluted with a diluent, and known mixing methods such as a rotary blade mixer or a ribbon blender can be used. When a diluent is used, it is better to remove the diluent by an appropriate method such as reduced pressure or heating after treatment. As the synthetic resin used in the present invention, thermoplastic resins or thermosetting resins known in the art can be used. Examples of thermoplastic resins include vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, vinyl alcohol resin, vinyl acetal resin, methyl methacrylate resin, polystyrene resin,
Polyamide resin, polyethylene resin, polypropylene resin, fluororesin, etc. can be used. As the thermosetting resin, known ones such as phenol resin, polyester resin, epoxy resin, silicone resin, melamine resin, alkyd resin, polyfunctional vinyl copolymer, etc. can be used. These can be used alone or in combination. The amount of synthetic resin blended is preferably 40 to 6% by volume in relation to other constituent components. still,
Additives such as stabilizers, antioxidants, and lubricants can be added depending on the purpose. The composition of the present invention is molded by applying a magnetic field to the above composition under heating and melting to orient the ferrite particles, and then cooling and solidifying the composition. Any known method can be used. The strength of the applied magnetic field must be 5,000 Oersted or more, preferably 10,000 Oersted, and more preferably 20,000 Oersted. The orientation degree needs to be 0.85 or more in order to make BHmax≧1.8. The synthetic resin magnet with high BHmax obtained in this way can be made into any shape depending on the purpose, such as a ring shape, a gear shape, a disc shape, etc.
Compared to conventional synthetic tree magnets of 1.7 MGOe or less, applications include motors, generators, magnet rolls, electronic buzzers, speakers, headphones, polarized relays, sensor magnets, etc. It is expected that this will contribute to the miniaturization of motors and improved performance (for example, improved torque in motors). A feature of the present invention is the addition of the above-mentioned specific substance, which makes it possible to maintain good fluidity during hot molding even when the magnetic powder content is increased, and even with a higher ferrite content than before. It can also be molded well. In addition, good fluidity during hot molding also makes it easier to rotate the ferrite particles, which means that the degree of orientation of the ferrite particles when a magnetic field is applied can be significantly improved. Combined with the ability to increase the ferrite content, it is possible to dramatically improve BHmax. Examples 1 to 5 Magnetoplumbite-type ferrite powder (average particle size 1.2μ) mainly composed of SrO・5.8Fe ₂ O ₃ was mixed with specific substances, synthetic resins, and additives in the proportions shown in Table 1. After mixing and kneading with a 32 mm kneader, the mixture was cooled and solidified, then crushed and made into pellets.Then, the resulting pellets were heated and melted to have the degree of orientation shown in Table 1. After applying the magnetic field shown in Table 1, the sample was cooled. As a result, as shown in Table 1, a material with a significantly high maximum energy product of 1.8 to 2.1 MGOe was obtained. Comparative Example 1 The same operation as in Example was carried out without using the specific substance of the present invention, but with the blending ratio shown in Table 1. As a result, the maximum energy product of the obtained resin magnet was extremely low at 1.03 MGOe. 【table】

Claims (1)

[Claims] 1. Magnetoplumbite type ferrite powder;
formula (In the formula, R ₁ is an alkyl group or an alkoxy group having 8 to 20 carbon atoms, and R ₂ , R ₃ , and R ₄ are a mixture of an alkoxy group and an alkyl group containing 1 to 3 alkoxy groups having 1 to 3 carbon atoms. ) A composition for a synthetic resin magnet, the basic components of which are a substance represented by the following formula and a synthetic resin. 2 The basic component is magnetoplumbite type ferrite powder of 60 to 94 volume percent, and the formula (In the formula, R ₁ is an alkyl group or an alkoxy group having 8 to 20 carbon atoms, and R ₂ , R ₃ , and R ₄ are a mixture of an alkoxy group and an alkyl group containing 1 to 3 alkoxy groups having 1 to 3 carbon atoms. ) Represented substances 0.1-2% by volume and synthetic resins
A composition according to claim 1 comprising 40 to 6 volume percent.