JPS6344708A - Composition for rubber magnet - Google Patents

Abstract

PURPOSE:To prevent discoloration and corrosion on a surface made of copper, copper alloy, silver, silver alloy, and the like, by using emulsion polymerized rubber which is polymerized by the use of ester phosphate group emulsion when a rubber magnet made of emulsion polymerized rubber is manufactured. CONSTITUTION:Polyoxyethylene alkyl monoester phosphate, polyoxyethlene alkyl diester phosphate, polyoxyethlene alkyl triester phosphate, and the like exemplify ester phosphate group emulsion. It is desirable that the amount of its use is within the range of 0.1-5 weight percent per 100 weight percent of monomer. Polybutadiene rubber, polyisoprene rubber, stylene-butadiene copolymerized rubber, acrylonitrile-butadiene copolymerized rubber, acryl rubber, or the like are exemplified as rubber used in this invention. A compositional material, which is obtained by mixing the above-mentioned emulsion polymerized rubber and magnetic powder by means of a usual mixer such as Banbury, a roller, or the like, is molded in a definite shape and vulcanized so that a rubber magnet can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a composition for a rubber magnet, and more particularly, a composition for a rubber magnet that is in contact with or adjacent to a rubber magnet at a close distance, in which rubber and a magnetic material are mixed. The present invention relates to a composition for a rubber magnet that has excellent discoloration resistance and corrosion resistance for copper, copper alloys, silver, and silver alloys.

(Prior Art) Rubber magnets made by adding ferrite magnetic powder or the like to emulsion polymerized rubber have been used for various purposes. When a rubber magnet is used in contact with or closely adjacent to copper, copper alloy, silver, silver alloy, etc., as in precision electronic components, such as inside a micromotor, the contact surface between the rubber magnet and the metal and the rubber Discoloration or corrosion may occur on the surface of the above-mentioned metals that are adjacent to the magnet at a close distance. This had the disadvantage of causing a decrease in conductivity.

(Problems to be Solved by the Invention) As a result of intensive research in order to solve the above-mentioned drawbacks, the present inventors found that when manufacturing rubber magnets using emulsion polymerized rubber, polymerization using a phosphorus-ugly ester-based emulsifier was carried out. The inventors have discovered that discoloration and corrosion on the surfaces of copper, copper alloys, silver, silver alloys, etc. can be prevented by using emulsion polymerized rubber, and based on this knowledge, they have completed the present invention.

(Means for Solving the Problems) This object of the present invention is achieved by using a composition for a rubber magnet comprising an emulsion polymerized rubber obtained using a phosphate emulsifier and a magnetic powder.

The emulsion polymerized rubber used in the present invention is a rubbery polymer obtained by ordinary emulsion polymerization using a phosphoric acid ester emulsifier as an emulsifier.

Examples of phosphate emulsifiers include polyoxyethylene alkyl phosphate monoester, polyoxyethylene alkyl diester phosphate, polyoxyethylene alkyl phosphate triester, polyoxyethylene alkyl phenyl phosphate monoester, and holoxyethylene alkyl phenyl phosphate. Examples include phosphoric acid zoester, polyoxyethylene alkylphenyl phosphoric acid triester, etc. The amount used is 0.1 to 5 parts by weight per 100 parts by weight of monomer.
A range of parts by weight is desirable. If it is less than 0.1 part by weight, the latex stability of the polymer will be insufficient, and if it is used in excess of 5 parts by weight, the effect will not improve and it will be uneconomical and undesirable.

Rubbers used in the present invention include polybutadiene rubber, polyiso! Examples include rubber, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylic rubber, etc., and each can be selected and used as appropriate depending on the purpose.

In the present invention, general ferrite magnetic powder is a typical example of the magnetic powder added to the composition for F9F magnets, but other magnetic powders such as rare earth Conolt magnetic powder and manganese-aluminum magnetic powder are also used. can do.

The amount of magnetic powder to be used is appropriately determined within the range of amounts normally used for each purpose, and is not particularly limited in the present invention.

The rubber magnet composition of the present invention can be obtained by mixing rubber and magnetic powder using a conventional mixer such as a Banbury mixer or a roll mixer. During mixing, in addition to the magnetic material, conventional compounding agents such as a vulcanizing agent, a vulcanization accelerator, various processing aids, and anti-aging agents are added. A rubber magnet is obtained by molding the obtained composition into a predetermined shape and vulcanizing it.

(Effects of the Invention) Thus, the present invention provides a composition for manufacturing rubber magnets that has superior discoloration and corrosion resistance for copper, copper alloys, silver, silver alloys, etc., compared to conventional techniques. .

(Example) The present invention will be described in more detail with reference to Examples below. Note that parts and parts in Examples and Comparative Examples are based on weight unless otherwise specified.

Examples 1 to 5 Using 3 parts of emulsifiers listed in Table 1 per 100 parts of monomer,
Polymerization was carried out at 5° C. for 15 hours according to a conventional emulsion polymerization recipe to obtain the polymer rubbers listed in Table 1.

100 parts of each of these polymers were mixed with 1000 parts of Ba ferrite powder using a 6-inch roll to prepare a composition for a rubber magnet.

[Discoloration, corrosion test]

The composition for rubber magnets was prepared into test pieces measuring 30 cm long x 15 cm wide x 5 cm thick, and as shown in Figure 1, two of the test pieces were thoroughly polished with a metal abrasive and then degreased. Each of the metal plates listed in the table was sandwiched, placed in a weighing bottle measuring 55 m in diameter x 60 cm in height, and the bottle was stoppered. The weighing pin was placed in a gear open at 100° C. and left for 40 hours, then taken out and the degree of discoloration and corrosion of the metal plate of each flower was visually confirmed. Results first
Shown in the table.

As is clear from the results in Table 1, the rubber magnet composition using emulsion polymerized rubber using a phosphate ester emulsifier does not discolor or corrode copper, copper alloys, silver, silver alloys, etc.

Comparative Examples 1 to 3 Discoloration and corrosion tests were conducted on rubber magnet compositions using emulsion polymerized rubber using emulsifiers other than those listed in Table 1 for discoloration and corrosion in the same manner as in the examples. Table 1 shows the results.

As is clear from the results in Table 1, discoloration and corrosion cannot be prevented with polymer rubbers using emulsifiers other than phosphate ester emulsifiers.

[Brief explanation of drawings]

FIG. 1 schematically shows a discoloration and corrosion test of a magnetic composition on a metal plate. Patent applicant Zeon Corporation Figure 1

Claims (1)

[Claims] A composition for a rubber magnet comprising emulsion polymerized rubber obtained using a phosphate emulsifier and magnetic powder.