JPH066642B2 - Composition for rubber magnet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rubber magnet composition. Specifically, it is a composition obtained by mixing powdered rubber and a powdery magnetic material, and has extremely excellent kneadability and pressure moldability. The composition of the present invention is processed and used as a rubber magnet in a wide range of fields including the electric field.

(Prior Art) Conventionally, rubber magnets have been manufactured by kneading a conventional bale rubber or chip rubber with a powder magnetic material using a kneading machine such as a kneading roll machine, an internal mixer, or a double-arm kneader. Then, a method obtained by performing pressure molding, vulcanization and magnetization is adopted.

However, in order to obtain a rubber magnet product in the above kneading, it takes a very long time to knead the rubber in order to knead a large amount of the magnetic material, and the magnetic material is hard, and the kneading machine is abraded greatly during the kneading. For this reason, the kneading machine is often repaired, regularly inspected, and sometimes the kneading machine itself needs to be renewed, so that the manufacturing cost is inevitably increased. On the other hand, during kneading, the rubber may be subjected to an extremely high shearing force due to a hard magnetic material to generate heat, and the rubber itself may deteriorate, resulting in poor mechanical properties of the obtained rubber magnet. Further, the kneaded mixture has a high viscosity because it is hard and a large amount of magnetic material is kneaded in rubber.
In pressure molding with a roll molding machine, an extrusion molding machine, a compression molding machine, a calender roll, etc., the flow of the kneaded material is poor, and a rubber magnet having a complicated and satisfactory shape cannot be obtained. For this reason, it is the actual situation that the emergence of a rubber magnet composition that solves these problems is strongly desired.

(Problems to be Solved by the Invention) In order to solve the above-mentioned problems and meet the demands, the present inventors have
As a result of earnest research, the present invention has been completed.

The present invention reduces the manufacturing cost, which is a problem when kneading a large amount of magnetic material with the above-mentioned rubber, can knead without impairing the mechanical properties of the obtained rubber magnet, and has excellent pressure moldability. A rubber magnet composition having a complicated and satisfying shape.

(Means for Solving Problems) The rubber magnet composition of the present invention comprises a powdery magnetic material having a Mooney viscosity of 5 or more and 30 or less at 100 ° C., which is obtained by a recently developed chemical method, and a powdery magnetic material. It is characterized by being obtained by adding and mixing. The obtained composition for rubber magnet is kneaded, pressure-molded, vulcanized and magnetized in the rubber processing step to be used as a rubber magnet product.

Hereinafter, the present invention will be described in detail.

A characteristic of the composition of the present invention is to use a powdered rubber obtained by a chemical method having a Mooney viscosity at 100 ° C. (hereinafter, the Mooney viscosity at 100 ° C. is referred to as Mooney viscosity) of 5 or more and 30 or less. It is in.

Generally, powdered rubber is produced by physical or chemical methods. Examples of the powdered rubber produced by the physical method include rubber obtained by pulverizing and crushing veil-shaped rubber or chip-shaped rubber, and rubber obtained by pulverizing rubber latex by spray drying, flash drying, freezing, or the like. The powdered rubber produced by the chemical method includes rubber powdered by coagulation, coprecipitation, microcapsule method, polymer ion complex or the like. The powder rubber used in the present invention is a powder rubber produced by a chemical method, particularly preferably a rubber powdered by a polymer ion complex method and having a Mooney viscosity of 5 or more and 30 or less. Powder rubber powdered by a physical method and having a Mooney viscosity of 30 or more is powdery immediately after powdering, but cannot be used as powder rubber because it causes agglomeration. The particle size of the rubber powder used in the composition of the present invention is not particularly limited, but is preferably 3 mm or less, more preferably 2 mm or less, and the particle size is 3 mm or less.
If it exceeds mm, it takes a long time for kneading by a kneading machine, which is not preferable.

As the powder rubber obtained by the chemical method in the present invention, natural rubber, polychloroprene rubber, acrylonitrile-butadiene copolymer rubber, polyisoprene rubber, ethylene-propylene copolymer rubber, polybutadiene rubber,
Examples thereof include powder rubbers such as styrene-butadiene copolymer rubber, chlorosulfonated polyethylene, and epichlorohydrin rubber. An example of the method for producing powder rubber obtained by these chemical methods is, for example, the method for producing powder rubber described in JP-A-53-73244. This is a mixture of an anionic or nonionic rubber latex with an anionic water-soluble polymer, and then a cationic polymer capable of causing coacervation with the anionic water-soluble polymer, a cationic surfactant, etc. After separating the rubber particles from the rubber latex, the synthetic resin emulsion is added and mixed,
A powdery rubber is obtained by dehydration and drying.

The Mooney viscosity referred to in the present invention refers to Japanese Industrial Standards, JIS
It refers to the viscosity measured based on the test equipment and measurement method specified in K 6300 (Unvulcanized Rubber Physical Test Method). The powdery rubber used in the present invention has a Mooney viscosity of 5 or more and 30 or less, preferably 10 or more and 20 or less. The powdery rubber obtained by a chemical method having a Mooney viscosity of less than 5 is powdery immediately after pulverization like the powdery rubber having a Mooney viscosity of 30 or less obtained by the physical method described above, but the composition of the present invention To obtain the composition of the present invention. Further, when a composition is obtained by using powdered rubber having a Mooney viscosity of more than 30, the Mooney viscosity of the kneaded product becomes high in the next kneading, and the rubber receives a high shearing force due to a large amount of magnetic material to generate heat. Therefore, the kneading machine must be constantly cooled with water during the kneading, and a rubber magnet product having a complicated and satisfactory shape cannot be obtained in the pressure molding of the kneaded product. That is, the Mooney viscosity obtained only by the chemical method is 5 or more and 3 or more.
The composition of the present invention can be obtained by using a rubber powder of 0 or less.

The magnetic material referred to in the present invention is a powdery magnetic material generally mixed in rubber magnets, for example, Ba-ferrite, Sr-ferrite, Ca-ferrite, Zn-ferrite, Co-ferrite, Mn-Zn ferrite, Cu. -Zn ferrite, Ni-Zn
Ferrite, Alnico, γ-iron oxide, Pt ・ Co, Pt ・ Fe, Mn
-Rare earths such as Al / C, pure iron, samarium cobalt, etc. can be mentioned. These can be used alone or in combination. The amount of these magnetic materials added to and mixed with the powder rubber is 100 to 200 per 100 parts by weight of the powder rubber.
0 parts by weight, preferably 400 to 1500 parts by weight, and more preferably 700 to 1200 parts by weight are added and mixed. 1
If the amount is less than 00 parts by weight, the rubber magnet product intended by the composition of the present invention cannot be obtained. If it exceeds 2000 parts by weight, the result of the rubber as a binder becomes small, the mechanical properties of the obtained rubber magnet product are deteriorated, and the industrial value becomes small.

The composition of the present invention is characterized in that it is granular or powdery,
A powder mixer is used as a method for obtaining the composition of the present invention. Examples of the powder mixer include a paddle mixer, a muller mixer, a tumble mixer, a ribbon blender, a high speed mixer, and a stirring blade type mixer.
Alternatively, an internal mixer, a double-arm kneader or the like used for kneading rubber may also be used. And it is obtained by mixing powdered rubber and powdery magnetic material with these powder mixers. If necessary, a compounding agent for rubber,
For example, a rubber vulcanizing agent, a vulcanization accelerator, an antiaging agent, a tackifier, a plasticizer, a softening agent and the like are appropriately added and mixed. The obtained composition of the present invention is kneaded with a kneading roll machine, an internal mixer, a double-arm kneader, or the like. In kneading, the composition of the present invention can be kneaded in an extremely short time, does not generate heat in the kneaded product, and has a low Mooney viscosity.
When this kneaded product is pressure-molded into a string shape by, for example, an extruder, a string having a beautiful surface texture can be obtained. Further, the composition of the present invention can be directly pressure molded by a pressure molding machine without using a kneading machine.

(Effects of the Invention) As is clear from the above description, the rubber magnet composition of the present invention reduces the manufacturing cost, which was a problem when manufacturing a rubber magnet product, and is suitable for pressure molding. It is an unprecedented composition characterized in that it can be pressure-molded into a complex and satisfying shape.

(Examples) The present invention will be described below with reference to Examples, but these are merely illustrative and do not limit the scope of the present invention.

The powder rubbers used in Examples 1 to 3 were manufactured by the following method.

Rosin potassium soap 4.0% by weight, caustic soda in nitrogen stream
0.4% by weight, 0.4% by weight of a condensate of formaldehyde and sodium naphthalene sulfonate are dissolved in 100% by weight of water,
Next, 100% by weight of chloroprene in which 0.35% by weight of n-dodecyl mercaptan and 0.1% by weight of 2,6-di-t-butyl-p-cresol were dissolved was added and emulsified, and a 1% aqueous solution of potassium persulfate was added at 40 ° C. Polymerization was carried out while dropping. Polymerization was stopped at 70% conversion, and unreacted chloroprene was distilled off to obtain a chloroprene polymer latex having a dry weight of 35%.

Next, using this latex, JP-A-53-73244
According to the method for producing powder rubber of No. 3, a powder rubber was produced by the following method.

To 300 g of the above chloroprene polymer latex, 1050 g of a 1% aqueous solution of an anionic water-soluble polymer (sodium carboxymethylcellulose) was added and mixed until a uniform solution was obtained, and 10% aqueous acetic acid solution was slowly added to obtain PH.
Adjusted to 6.3. Next, this mixed solution was added to a 0.5% aqueous solution 4200 containing 2% by weight of acetate of a higher amine (polyoxyethylene tallow alkyl propylene diamine).
The polymer immediately separated into a powder when it was added to gram with stirring at room temperature. The PH after the powder separation was 4.9.
Then, a wet polymer was obtained which was separated by a cotton cloth, washed, and then dehydrated by a centrifuge to easily become a powder by hand. Further, powder chloroprene rubber (hereinafter referred to as powder CR) having a particle diameter of 1 mm was obtained by a fluidized drier. The Mooney viscosity of the obtained powder CR was 8.

The powder CR used in Examples 4 to 5 and Comparative Example 3 was changed from 0.35 wt% of n-dodecyl mercaptan to 0.30 wt% in the production of the powder rubber of the powder CR used in Examples 1 to 3, Powder CR was obtained by the same operation as above. The Mooney viscosity of the obtained powder CR was 20.

The powder CR used in Comparative Example 2 is Toyo Soda Industry Co., Ltd.
The chloroprene rubber latex of SKYPRENE B-30 was prepared so as to have a dry weight of 35%, and then powder CR was prepared by the same operation as the above-described method for producing powder rubber of JP-A-53-73244. Obtained. The Mooney viscosity of the obtained powder CR was 53.

Examples 1 to 3 and Comparative Examples 1 and 2 In Example 1, powder CR was placed in a stirring blade mixer of 30
In addition, 100 parts by weight of powder CR used, Ba-ferrite, which is a magnetic material (FEROTOP manufactured by Toda Kogyo KK)
GR-500), 500 parts by weight, 5 parts by weight of zinc, 4 parts by weight of magnesium oxide, 0.8 parts by weight of ethylenethiourea, and 8 parts by weight of naphthenic oil are added, and the rotor is rotated at 850 rpm for 20 seconds at room temperature. Then, a composition for a rubber magnet was obtained. Next, with an 8-inch roll manufactured by Toyo Seiki Seisaku-sho, Ltd., the time from when the mixture was put into the rubber magnet composition roll to when a kneaded product was obtained was measured. The kneading time is shown in Table-1. Next, the kneaded product was filled in a 2 mm sheet molding die, and the die was pressed at 180 ° C. for 25 minutes at 50 kg / cm ² ,
Pressure molding vulcanization was performed. In order to know the mechanical properties of the obtained 2 mm sheet, the tensile strength was measured according to JIS K6301. The measurement results are shown in Table-1. On the other hand, in order to know the fluidity of the obtained kneaded product, the Mooney viscosity of the kneaded product was measured. Table 1 shows the measurement results.

In Example 2, 1 part by weight of 500 parts by weight of Ba-ferrite of Example 1 was used.
The same method as in Example 1 was followed except that the amount was changed to 000 parts by weight.

In Example 3, 1 part by weight of 500 parts by weight of Ba-ferrite of Example 1 was used.
The same method as in Example 1 was followed except that the amount was changed to 500 parts by weight.

In Comparative Example 1, the powder CR of Example 1 was replaced with chip CR having a Mooney viscosity of 52 (Skyprene B- manufactured by Toyo Soda Kogyo Co., Ltd.).
30), and the composition of Comparative Example 1 shown in Table 1 was kneaded with an 8-inch roll to obtain a kneaded product. It took 25 minutes for kneading. The obtained kneaded product was subjected to measurement of Mooney viscosity and tensile strength in the same manner as in Example 1.

In Comparative Example 2, powder CR was used to obtain a composition in the same manner as in Example 2, and then kneading was performed with an 8-inch roll. The kneaded product was poorly wound around the roll, and the kneaded product was bare handed. However, the temperature was too high to hold and kneading could not be done, so kneading was stopped.

From Table-1, it can be seen that the rubber magnet compositions of Examples 1 to 3 can be kneaded in an extremely short time as compared with Comparative Example 1. In addition, Examples 1 to 3 have significantly lower Mooney viscosities than Comparative Example 1, and it is clear that they show extremely excellent fluidity in pressure molding, which is obtained only by a chemical method. Mooney viscosity of 5 or more 30
It is considered that the following powder CR increases the fluidity of the kneaded product. The tensile strength of the 2 mm sheets obtained in Examples 1 to 3 was obviously higher than that in Comparative Example 1. Although this is an estimate, the rubber magnet compositions of Examples 1 to 3 have a short kneading time on the rolls, and the low Mooney viscosity of the kneaded product causes a small heat generation of the kneaded product in the kneading. It is probable that the rubber did not deteriorate.
On the other hand, in Comparative Example 1, the kneading time is long and the Mooney viscosity of the kneaded product is high, so that the kneaded product generates a large amount of heat during the kneading, the rubber is deteriorated, and the tensile strength is considered to be low.

Examples 4 and 5 and Comparative Example 3 In Example 4, 500 parts by weight of the Ba-ferrite of Example 1 was added to Sr.
-Ferrite (Feroto G manufactured by Toda Kogyo Co., Ltd.)
P-941) The same procedure as in Example 1 was repeated except that the amount was changed to 700 parts by weight.

In Example 5, 1 part by weight of 700 parts by weight of Sr-ferrite of Example 4 was used.
The same method as in Example 4 was followed except that the amount was changed to 200 parts by weight.

In Comparative Example 3, 700 parts by weight of Sr-ferrite of Example 4 was added.
A kneaded product was tried to be obtained in the same manner as in Example 4 except that the amount was changed to 500 parts by weight. However, in the roll kneading, the heat of the kneaded product was high and the kneading of the kneaded product on the roll was poor, so that the roll work was performed. However, the kneading was stopped.

As shown in Table 1, the rubber magnet compositions of Examples 4 and 5 were able to be kneaded in a short time, the Mooney viscosity of the kneaded product was low, and the obtained 2 mm sheet exhibited high tensile strength. In the roll kneading of Comparative Example 3, the exothermic heat of the kneaded product was high, and the reason why the winding around the roll was poor was that the amount of ferrite was 2000.
If it exceeds the weight part, it is considered that the effect of the rubber on the fluidity of the kneaded product becomes small and the Mooney viscosity becomes abnormally high, and the effect of the rubber as a binder for ferrite becomes small.

Claims (1)

[Claims] 1. A Mooney viscosity at 100 ° C. of 5 or more 3
A rubber magnet composition comprising 100 to 2000 parts by weight of a powdery magnetic material added and mixed with 100 parts by weight of a powdered rubber obtained by a chemical method of 0 or less.