JPS6032125A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain efficiently a magnetic disc having high performance at a low cost washing a substrate with a prescribed washing liquid then providing a magnetic layer thereon. CONSTITUTION:A material which dissolves org. materials such as cutting fluid, etc. sticking on the surface of a disc substrate, for example, perchloroethylene, trichloroethylene and other defatting agents and a material which removes inorg. materials such as machining swar, salts, etc. sticking on the surface of the disc substrate, for example, an aq. soln. contg. an acid, alkali, etc. are mixed and a nonionic surface active agent in particular is added thereto to emulsify the mixture. The surface of the substrate is washed with such emulsion washing liquid and is then washed with pure water. A magnetic layer is formed on the surface of the substrate after drying. The magnetic disc having high performance is thus obtd. efficiently at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium, in which a magnetic recording medium substrate is ultrasonically cleaned using, for example, an emulsion aqueous solution containing a degreasing solvent and a surfactant, and then the magnetic recording medium substrate is cleaned. By manufacturing a magnetic recording medium through the steps of drying and providing a magnetic layer on the surface of the hindlimb magnetic recording medium,
The time required to manufacture magnetic recording media can be shortened, the efficiency of manufacturing magnetic recording media can be significantly improved and costs can be reduced, and the equipment for manufacturing magnetic recording media can also be simplified and equipment costs can be reduced. Furthermore, the safety of manufacturing magnetic recording media has been improved, and the resulting magnetic recording media have no defects such as uneven thickness of the magnetic layer or pinholes. The purpose is to provide

For example, in order to improve the characteristics of magnetic recording media such as magnetic disks, research has been carried out on magnetic layers provided on substrates, and various proposals have been made to develop excellent magnetic disks.

However, the characteristics of a magnetic disk depend not only on the magnetic layer provided on the substrate, but also on the substrate on which the magnetic layer is provided,
In particular, it has been found that failure is also affected by the surface properties of the substrate. In other words, when coating a magnetic recording medium on a magnetic disk substrate made of aluminum alloy, etc., if there are foreign substances such as minute cutting shoulders or dust on the substrate, it may be difficult to form a uniform magnetic layer due to these foreign substances. In addition, if there is organic dirt or residual cutting oil on the substrate, the wettability of the substrate surface will change when forming a magnetic coating layer by, for example, staining/coating. As a result, the magnetic paint does not spread uniformly, resulting in uneven thickness and pinholes in the magnetic paint film, which greatly deteriorates the characteristics of the magnetic disk.

Therefore, in order to eliminate such defects, conventionally, a disk substrate made of aluminum alloy or the like is immersed in a degreasing solution such as perchlorethylene to dissolve organic matter, cutting oil, etc. attached to the surface of the disk substrate. After removal, the surface of the disk substrate can be cleaned by steam drying, then immersing it in an aqueous detergent solution to clean it, and finally cleaning it with pure water and drying it. It is planned.

However, in such a disk substrate cleaning process, the degreasing process and the detergent cleaning process are separate, so the processing time becomes longer, the processing equipment becomes larger, and furthermore, the vapor from the degreasing solvent is dangerous. This increases security, requires safety measures, and significantly increases processing costs, leading to an increase in the cost of magnetic disks.

The present invention eliminates the above-mentioned drawbacks, that is, it uses perchlorethylene, trichlorethylene, etc., which dissolve organic substances such as cutting oil adhering to the disk substrate surface.
A degreasing solvent such as kerosene, IPA, or fluorine-based solvent is mixed with an aqueous solution containing, for example, acid, alkali, or builder, which removes the cutting layer and inorganic substances such as salts adhering to the surface of the disk substrate. In particular, the disk substrate surface is cleaned with an emulsion cleaning solution containing a nonionic surfactant and emulsified using a stirring device such as a homogenizer, using an ultrasonic cleaning device or a bubbling cleaning device, and then cleaning with pure water. After drying, a magnetic layer is coated on the surface of the disk substrate, and this magnetic coating is baked and hardened. We have discovered that it is possible to provide

Oka, if there is a lot of adhesion of organic substances on the disk substrate surface, use a surfactant with HLB7-8 to make the O/W type, and if there is a lot of adhesion of organic substances, use a surfactant with HLB3-6 to make the w10 type. It is desirable to use an emulsion cleaning solution adjusted to the mold.

Hereinafter, specific examples of the magnetic recording medium manufacturing method according to the present invention will be described.

Example 1 First, for example, 20% by weight of perchlorethylene, NP-1
0 (manufactured by Nikko Chemicals) 4% by weight, op-IQ (manufactured by Nikko Chemicals) 4% by weight, 2 parts by weight of sodium silicate,
An O/W type emulsion cleaning liquid having a composition of 70% by weight of pure water is prepared, and the surface of a magnetic disk substrate made of aluminum or aluminum alloy is cleaned with this emulsion cleaning liquid using an ultrasonic cleaning device.

Then, the magnetic disk substrate cleaned with the emulsion cleaning liquid is cleaned with pure water, and then this magnetic disk substrate is dried.

Next, a magnetic paint containing a mixture of magnetic powder, binder, and other additives is applied to the clean magnetic disk substrate obtained as described above and dried, followed by baking, curing, and polishing. A magnetic disk is made through the following steps.

Example 2 Fronsolve (manufactured by Asahi Glass ■) 10% by weight, NP-10 (
Nikko Chemicals ■) 4% by weight, NP-15 (Nikko Chemicals ■) 4% by weight, sodium silicate 2% by weight, pure water 8%
An o/w type emulsion cleaning solution having a composition of 0% by weight was prepared, and the cleaning was carried out in the same manner as in Example 1, except that this emulsion cleaning solution was used instead of the emulsion cleaning solution of Example 1, and the magnetic disk was cleaned. make.

Comparative Example As in Example 1, a magnetic disk substrate was degreased using Freonsolp, the degreasing solvent adhering to the surface of the disk substrate was removed by drying, and the disk substrate was subjected to P3.
The magnetic disk was cleaned with a 5% by weight aqueous solution of T580 (manufactured by Henkel Hakusui ■) using an ultrasonic cleaning device, washed with pure water after this cleaning, dried, and then provided with a magnetic layer in the same manner as in Example 1. make.

Comparing the above Example and Comparative Example, for example, if the cleaning time of the magnetic disk substrate is the same, cleaning by the processes of Examples 1 and 2 is more effective than cleaning by the process of Comparative Example. The surface of the magnetic disk substrate is even cleaner as a result of cleaning, and the time required to clean the surface of the magnetic disk substrate to the extent that it does not adversely affect the magnetic layer is just under 3 minutes in the example. On the other hand, the comparative example required just over 6 minutes, which is more than twice the time when using the emulsion cleaning solution as in the example. It turns out that cleaning the recording medium substrate is extremely effective.

In addition, the equipment required to clean the magnetic disk substrate is simple in the case of the present invention, and when comparing the above embodiment and the comparative example, the equipment cost in the comparative example is twice as much as that in the embodiment. Ru.

In addition, in the case of the comparative example, safety measures are required due to the solvent vapor that evaporates during the degreasing process, which increases the size of the equipment and increases the cost, whereas in the case of the example 1,
As shown in 2, in the case of the present invention, the amount of evaporation of the degreasing solvent is not a problem, it is highly safe, and special equipment required for safety is not required, and it can be carried out with simple equipment. .

Furthermore, when an ultrasonic cleaning device is used, if an emulsion aqueous solution containing a degreasing solvent and a surfactant is used as a cleaning liquid, it will be easier to clean aluminum or aluminum alloys than when ultrasonic cleaning is performed simply using a surfactant aqueous solution. shall not damage the surface of the disc substrate,
becomes highly desirable.

As described above, the method for manufacturing a magnetic recording medium according to the present invention includes cleaning a magnetic recording medium substrate with a cleaning liquid that is a mixed emulsified mixture of a substance that removes organic substances attached to the surface of the magnetic recording medium substrate and a substance that removes inorganic substances. After washing with water, a magnetic layer is provided on the surface of the magnetic recording medium substrate, so that, for example, a magnetic paint can be uniformly applied to the surface of the magnetic recording medium substrate, resulting in excellent magnetic recording without uneven thickness of the magnetic coating film or pinholes. media became possible, and the manufacturing process for magnetic recording media was also reduced.
The time required for manufacturing is shortened, manufacturing efficiency is significantly improved, manufacturing equipment is simpler, equipment costs are lower, and manufacturing costs for magnetic recording media are lower. Furthermore, it has features such as high safety during manufacturing.

Patent applicant: Victor Japan Co., Ltd.

Claims (1)

[Claims] After cleaning the magnetic recording medium substrate with a cleaning liquid that is an emulsified mixture of a substance that removes organic substances and a substance that removes inorganic substances attached to the surface of the magnetic recording medium substrate, a magnetic layer is formed on the surface of the magnetic recording medium substrate. A method for manufacturing a magnetic recording medium, comprising: providing a magnetic recording medium;