JPS6044806B2 - Method for producing a composition for permanent magnets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a permanent magnet composition having excellent magnetic properties and processability.

More specifically, general formula Mo-nFe. O. (wherein M is one or more selected from the group of Ba, Br and Pb, and n is a number from 4.5 to 6.2) and liquid rubber, The ferrite powder and phase. When mixing ferrite powder, liquid rubber, and polar organic compound in the coexistence of a certain polar organic compound for working purposes to produce a composition for permanent magnets, 0.05 to 0.5 weight of ferrite powder is added to the ferrite powder when kneading the ferrite powder, liquid rubber, and polar organic compound. The present invention relates to a method for producing a permanent magnet composition with excellent magnetic properties and workability, which is characterized by adding % of stearic acid or a metal salt of stearic acid. Conventionally, rubber or plastic magnet compositions are known in which ferrite powder is mixed into a rubber or plastic matrix to improve the workability and flexibility of sintered ferrite magnets.

Generally, these compositions are made by kneading ferrite powder and a solid polymer, and then molding the mixture by extrusion or calendaring.
The magnet composition formed in this way has excellent workability and, in some cases, flexibility and elasticity compared to sintered ferrite magnets, and is used for various purposes. It cannot be used for applications that require. The magnetic force of the magnet composition depends on I) the loading of ferrite and (2) the degree of orientation of the ferrite particles in the matrix. Normally, when blending ferrite powder into a polymer, there is an upper limit to the amount of ferrite filled. For example, when natural rubber is used as the polymer, it is not possible to blend ferrite in an amount exceeding 9 times the weight of natural rubber. Can not. On the other hand, although not all of the factors that regulate the degree of orientation of ferrite particles in the matrix have been clarified, it has been empirically shown that as the viscosity of the matrix increases during kneading, the degree of orientation decreases. known to. The present inventors have previously considered the above points, and in order to improve the ferrite filling amount and the orientation of ferrite particles, the present inventors have proposed using liquid rubber as a matrix, and interacting the ferrite powder and liquid rubber with the ferrite powder. He proposed kneading in the coexistence of certain polar organic compounds (patent application filed in 1983).
-14426 Wani and Japanese Patent Application No. 1442-1983).

The present invention has been achieved as a result of further detailed study of the above invention. That is, when kneading liquid rubber and hard magnetic ferrite powder in the coexistence of a polar organic compound that interacts with the ferrite, 0.
By adding 0.5 to 0.5 weight percent of stearic acid or a metal salt of stearic acid, the viscosity of the composition is significantly reduced, resulting in an improvement in the degree of orientation of the ferrite particles and thus in the magnetic properties, making it easier to process further. It was found that the properties were improved. For example, liquid polybutadiene (average molecular weight 4,000) and barium ferrite 9 times the weight of the barium ferrite. When kneading using a plus l graph in the coexistence of 5% by weight of methyl oleate, the rotational torque is 75 k9 when no stearic acid or its metal salt is added; Against 0. Addition of pore weight percent zinc stearate lowers it to 37k9.Cm while increasing the (B.H)Max of the composition by 10-20%. Even if 0.2 to 0.5 weight percent of a polar organic compound such as methyl oleate or tri-n-butylamine is added to the ferrite instead of stearic acid or its metal salt, the torque decreases and (B-H) Max
Since no improvement was observed in stearic acid, the effect of the addition was found to be unique to stearic acid or its metal salts. Ru.
The liquid rubber used in the present invention is a rubber that is liquid at room temperature in the absence of a solvent, and includes liquid polybutadiene, liquid polyisoprene, liquid polyisobutylene, and liquid polymers thereof. A wide variety of derivatives can be used, including derivatives into which hydroxyl groups, carboxyl groups, maleic anhydride groups, isocyanate groups, acrylic groups, etc. have been introduced, but for the sake of explanation below, liquid polybutadiene polymers will be detailed as a representative example. There is.

The average molecular weight of the liquid polybutadiene used is 1,00
It must be within the range of 0 to 10,000. When the average molecular weight is less than 1,000, the chain length is too short, and as a result, the liquid polybutadiene does not function as a binder or matrix for the ferrite powder. On the other hand, if the average molecular weight exceeds 10,000, the viscosity of the composition becomes too high, making it impossible to mold it using normal molding means. On the other hand, the higher the mixing ratio of ferrite to liquid rubber, the more desirable it is from the viewpoint of magnetic properties. For example, when liquid polybutadiene is used as the liquid rubber, if the mixing ratio is less than 5 times by weight, a magnet composition having a practical magnetic force cannot be obtained. On the other hand, if the mixing ratio exceeds 14 times by weight, the viscosity of the composition becomes too high, resulting in poor flow during molding, resulting in a lower degree of orientation and lower moldability. The ferrite powder used in the present invention is a high magnetic oxide having a hexagonal crystal structure, such as BaO-6F'
E2O3, SrO・6F'E2O3, PbO-6F'E
Oxide powder having a composition of 2O3 is preferably used.
As for the properties of the ferrite powder, it is required that it be easily kneaded with liquid rubber, and plate-shaped ferrite powder having an average particle diameter in the range of 1 μm to 3 μm is particularly preferred. Polar organic compounds that interact with the ferrite powder used in the present invention include carbonyl compounds, carboxylic acid ester compounds,
Amine compounds, epoxy compounds, etc. are widely used.
More specifically, carbonyl compounds include aldehydes such as n-butyraldehyde and benzaldehyde;
Ketones such as diisopropyl ketone and methyl ethyl ketone; carboxylic acid ester compounds such as methyl laurate and methyl oleate; amine compounds such as tri-n-butylamine, hexamethylenediamine, and laurylamine; and epoxy compounds such as epichlorohydrin and propylene oxide. etc. The entire required amount of these compounds may be added during kneading, but some or all of the required amount may be treated in advance into ferrite powder using a well-known gas phase method or liquid phase method as a surface treatment method. The effect of the addition is even more pronounced. The amount of the polar organic compound added is preferably in the range of 0.1 to 5 weight percent based on the ferrite powder. If the amount added is less than 0.1%, no effect will be observed, while if it exceeds 5% by weight, the mechanical strength of the composition will decrease, and the surface of the composition will become sticky, a so-called bleed phenomenon. Hail. The metal used as the metal stearate is not particularly limited, and examples include sodium, potassium, barium, magnesium, calcium, zinc, aluminum, and lead.

The amount of stearic acid or its metal salt added is preferably in the range of 0.05 to 0.5 weight percent based on the ferrite. If the amount added is less than 0.05 weight percent, no effect will be observed, and if it is more than 0.5 weight percent, the crosslinking reaction will be significantly inhibited, as will be described later. The ferrite powder and liquid rubber can be mixed by various kneading methods commonly used in plastic molding.

This is compared to the blending of ferrite into solid rubbers such as natural rubber, which is limited to roll kneading.
It can be said that the advantages in the processing process are extremely large. Next, the kneaded composition is fed into an injection molding machine, an extrusion molding machine, a compression molding machine, a calender molding machine, etc. to be molded into an arbitrary shape. The composition according to the present invention can be easily cured by adding a crosslinking agent or a vulcanizing agent during kneading, and can be made flexible by selecting an appropriate curing agent as needed. It is also possible to obtain compositions.

The magnet composition obtained according to the present invention can be used for various purposes by changing the blending ratio of ferrite and liquid rubber.

That is, when the blending ratio of ferrite/liquid rubber is relatively small, it can be used in refrigerator gaskets and miscellaneous goods, etc., in which conventional rubber magnets are used. On the other hand, ferrite/
The compounding ratio of liquid rubber is large (B-H) Max is 0.9M
Compositions of GG or higher can be used as a substitute for sintered magnets for micro motors, etc., for which it has been conventionally impossible to use rubber magnets due to their weak magnetic force. EXAMPLES The present invention will be specifically explained below with reference to Examples, but these are not intended to limit the present invention in any way.

Examples 1 to 5 Iron oxide and barium carbonate were mixed into Fe2O3/
Mix so that the molar ratio of BaO is 5.75, and
Barium ferrite powder 1k9 and methyl oleate 20y, which had been calcined at a temperature of 50°C and then ground to about 1.4 μm, were heated at 180°C for 1 hour with stirring. The methyl oleate-treated barium ferrite thus obtained was subjected to the following experiment. Butadiene homopolymers with an average molecular weight of 4,000 NISSOPB-4 manufactured by Ichidamoto Soda Co., Ltd.
000) Barium ferrite treated with methyl oleate at a predetermined weight times 0. A crosslinking agent, tert-butyl peroxybenzoate (Halfthyl Z manufactured by NOF Corporation) was added at 70° C. and 20% by weight based on the weight percent of zinc stearate and polybutadiene.
The mixture was kneaded using a Plastograph manufactured by Braventa under conditions of r'Pm, and then press-molded for 5 minutes at 180° C. and under pressure of 50 k9/d while applying a magnetic field of 5,0000 e.

The magnetic properties of the obtained molded products are shown in Table 1 together with the results when no stearate was added (Comparative Examples 1 to 3). Examples 6 to 10 Iron oxide and strontium carbonate were combined into Fe2O3/SrO.
Strontium ferrite powder 1k9 and methyl oleate 20 were mixed so that the molar ratio of
q was heated at 180° C. for 1 hour with stirring.

The strontium ferrite treated with methyl oleate thus obtained was subjected to the following experiment. NISSOP
B-4,000 and strontium ferrite treated with methyl oleate twice the specified weight, 0. Heel weight percent aluminum stearate and NISS
3 weight percent of Half Chill Z was kneaded with respect to OPB-4,000 under the same conditions as in Examples 1 to 5, and then 1
10,0000e at 80℃ and 50k9/Clt pressure
Press molding was performed for 5 minutes while applying a magnetic field of . The magnetic properties of the obtained molded products are shown in Table 2 together with the results when no stearate was added (Comparative Examples 4 to 5). In addition, when 0.7 weight percent of aluminum stearate was added to the ferrite, the curing reaction did not proceed sufficiently even if the three powders were press-molded at 180°C and a pressure of 50k9/Cfl, resulting in a good molded product. I couldn't get it.

Claims (1)

[Claims] 1 General formula MO・nFe_2O_3 (where M is Ba
, Sr, and Pb, where n is a number from 4.5 to 6.2), and liquid rubber are mixed with the ferrite powder and liquid rubber. When blending in the coexistence of a certain polar organic compound to produce a permanent magnet composition, 0.05 to 0.5 weight percent of stearin is added to the ferrite powder when kneading the ferrite powder, liquid rubber, and polar organic compound. A method for producing a permanent magnet composition with excellent magnetic properties and workability, which comprises adding an acid or a metal salt of stearic acid.