JPS59127729A - Manufacture of magnetic film - Google Patents

Abstract

PURPOSE:To obtain a thin magnetic film whose surface is smooth and free from pinholes, by rolling a magnetized magnetic film consisting of a thermoplastic resin and a magnetic powder between a pair of pressure rolls at a temperature lower than the softening temperature of said resin. CONSTITUTION:A magnetized magnetic film consisting of 100pts.wt. thermoplastic resin (e.g. chlorinated PE, PVC etc.) and 300-1,500pts.wt. magnetizable magnetic powder (e.g. barium ferrite, strontium ferrite, etc.) is rolled between at least a pair of pressure rolls at a temperature lower than the softening temperature of said thermoplastic resin so that the thickness of the magnetic film may be reduced to 1/2-1/10. A magnetic film whose surface is smooth and free from a pinhole and whose thickness is 0.5mm. or less can be readily produced. The thus produced magnetic film is thin, therefore can be made lightweight and compact, and can be suitably used for a sticker, poster, boy as well as precision machine, motor, electric home appliance, etc.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a magnet film.

Conventionally, plastic magnets have been used in a wide range of applications such as stickers, posters, refrigerators, microwave ovens, watches, televisions, motors, and vending machines. is heated and kneaded and molded using a molding method such as injection molding, extrusion molding, or press molding, so when trying to mold a thin sheet-like product, pinholes occur and unevenness is created on the surface.
Only those thicker than 5 m could be obtained industrially and efficiently. For this reason, it could not be made sufficiently lightweight and compact, and could not be suitably used in precision machines, motors, household appliances, and the like.

In view of the above-mentioned drawbacks, the present invention has been made to provide a method for producing a thin magnetic film with a smooth surface and no force and no holes.
00 parts by weight and 300 to 1,500 parts by weight of magnetized magnetic powder.
A method for producing a magnetic film, which comprises rolling the sheet to a thickness of 5 to 1/2 to 1/10 that of the sheet by pressing it between at least a pair of rolling rolls at a temperature lower than the finger softening temperature. have

The thermoplastic resin used in the present invention preferably has excellent film performance and binding properties, such as olefins such as polyethylene, polypropylene, chlorinated polyethylene, and ethylene/vinyl chloride copolymer. The magnetic powder used in the present invention may be any magnetic powder that is magnetized and resistant, such as fluorite such as strontium ferrite and paricum ferrite, SmCo5, SmzCozy,
Examples include rare earth metals such as SmV and SmEu, and the smaller the particle size, the better, and generally those with α1 to 5μ are used.

The magnetic sheet used in the present invention is made of the above-mentioned thermoplastic resin and magnetic powder and is dusty. If the amount of magnetic powder added is small, the adsorption force will be small when magnetized, and if it is too large, it will be difficult to form a sheet. Since rolling becomes impossible, 300 to 1,500 parts by weight of magnetic powder is added to 100 parts by weight of thermoplastic resin, preferably 500 to 1,000 parts by weight.

Further, any method may be used to manufacture the magnetic sheet, and examples include injection molding, extrusion molding, calendar molding, press molding, etc.
Preferably, it is formed to a thickness of ~3 wings.

The above-mentioned magnetic sheet is magnetized to form a magnet sheet, and a conventionally known method may be used for magnetization.

In the present invention, the magnetic sheet is compressed and rolled between at least a pair of rolling rolls, and the rolling is performed at a temperature lower than the softening temperature of the thermoplastic resin. When the magnetic sheet is heated to a temperature lower than the softening temperature and rolled, the rolling roll may be heated or a preheating device may be used. In addition, at least one pair of rolling rolls is sufficient, and the linear pressure thereof is 100 to 2000 kg 1 am
It is preferable that the magnetic sheet is rolled to a thickness of 1/2 to 1/10. In addition, rolling a thermoplastic resin sheet such as polyethylene, chlorinated polyethylene, polyvinyl chloride, butyl nitrile rubber, nylon, etc. or a web film on one side or both sides of the magnetic sheet will make rolling easier and prevent pinholes from forming. The composition of the present invention is as described above, and a magnetized sheet made of a thermoplastic resin and magnetic powder is heated to 1/2 to 1 at a temperature lower than the softening temperature of the thermoplastic resin. Since the magnetic film is rolled to a thickness of 1/10 mm, it is possible to easily produce a magnetic film thinner than 0.5 cm with a smooth surface and no pinholes.

The obtained magnetic film is thin and lightweight, and the magnetic film is thin and lightweight.
It can be suitably used for suit cars, posters, toys, miscellaneous goods, precision machinery, motors, household electrical appliances, etc.

patent applicant Sekisui Chemical Co., Ltd. Representative: Mototoshi Fujinuma

Claims (1)

[Claims] 1 100 parts by weight of thermoplastic resin and magnetic powder 3
00 to 1,500 parts by weight, a magnetized sheet is compressed between at least a pair of rolling rolls at a temperature lower than the softening temperature of the thermoplastic resin to reduce the amount of 1/2 of the sheet.
A method for manufacturing a magnet film, which comprises rolling to a thickness of 2 to 1/10.