JPS5894131A - Metallic thin film type magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the anticorrosion and lubricating properties of titled medium, by making high-molecular surface active agents adsorbed on a ferromagnetic metallic thin film. CONSTITUTION:After an aqueous solution of an ionic high-molecular surface active agent such as a carboxylic acid type high-molecular surface active agent, a sulfate type high-molecular surface active agent, a sulfonic acid type high- molecular surface active agent, an amine type high-moleacular surface active agent and a quat. ammonium salt type high-molecular surface active agent is applied on a ferromagnetic metallic thin film, this substance is washed with a large quantity of pure water to wash away the high-molecular surface active agent which is not adsorbed. Polyvinyl potassium sulfate, sodium naphthalenesulfonate-formalin condensate, sodium alpha-olefin-sulfonate and sodium polyacrylate etc. are used actually used as surface active agents.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal thin film magnetic recording medium, and particularly to a metal thin film magnetic recording medium in which the surface of the magnetic layer is modified to improve corrosion resistance and slipperiness.

Metal thin film magnetic recording media manufactured by vacuum evaporation or plating are said to be suitable for high-density recording. In particular, in recent years, it has been expected to be used as audio tapes and video tapes. However, in general, ferromagnetic metal thin films are easily corroded. In order to avoid this, methods such as alloying the magnetic material itself or forming a film of a polymer compound or the like on the magnetic layer have been adopted. However, in the case of alloying, from the viewpoint of magnetic properties, an alloy with good corrosion resistance cannot necessarily be said to have good properties. Further, although forming a corrosion-resistant coating such as a polymer compound on the surface of the magnetic layer is effective, it is not preferable from the viewpoint of electromagnetic conversion characteristics because the coating layer becomes thick. The permissible range of the thickness of the coating layer is at most 500 mm, preferably about 20 mm. It is extremely difficult to uniformly form a corrosion-resistant coating having such a thickness and with good mass productivity. Further, with such a thickness, it is difficult to completely prevent moisture from entering.

In addition, thin metal film magnetic recording media have insufficient lubricity due to random metal-metal contact;
It is difficult to obtain smooth contact with the head, and it has drawbacks such as large fluctuations in output.

The present invention solves these problems with conventional products by adsorbing a water-soluble polymeric surfactant to a magnetic layer made of ferromagnetic metal, which has sufficient corrosion resistance and lubricity. It was possible to obtain a metal thin film type magnetic recording medium.

The water-soluble polymeric surfactant in the present invention refers to an ionic polymeric surfactant, that is, an anionic polymeric surfactant and a cationic polymeric surfactant. For example, polyacrylic acid, sulfate ester type polymeric surfactants such as copolymer salts with styrene, ethylene, imbutylene, etc., naphthalene sulfonate formalin condensates *
e) Sulfonic acid type polymeric surfactants such as sulfonic acid salts such as styrene/sulfonic acid and σ-olefin sulfonic acid, amine type polymeric surfactants such as polyvinylamine, quaternary ammonium salts of polyvinylpyridine, etc. Grade ammonium salt type polymeric surfactants and the like can be applied to the present invention.

The water-soluble polymer surfactant in the present invention has an aqueous solution concentration of 10 F/42 to 0,0001 y/
j! It is 0.001F/ρ. If the concentration of the polymeric surfactant exceeds 10y/ρ, the unadsorbed polymeric surfactant will not be sufficiently washed away in the water washing process after adsorbing the polymeric surfactant, and it will remain in a micellar state. I will do it. The unadsorbed polymer parts tend to peel off when the tape is running, and the peeled off parts accumulate in the magnetic head, causing clogging and dropouts.

Also, the concentration is 0.0o01y/! If it is less than that, a uniform adsorption film cannot be formed on the magnetic metal thin film, and only insufficient corrosion resistance can be obtained.

Next, the manufacturing method of the present invention will be explained.

1oy/1~o, ooo1y/I! , (7) Applying an aqueous solution of a polymeric surfactant onto a magnetic metal thin film using various coating methods. Next, the immersion method and the flowing method.

Rinse with a large amount of pure water using a spray method to wash away unadsorbed polymer surfactant. Coating liquid 10
It is recommended to wash with more than twice as much water.

Furthermore, the washing process may be repeated to ensure complete washing. After washing with water, the air knife method is effective because it does not damage the surface of the magnetic thin film, which removes moisture using various blades. After draining, dry.

In this way, a polymer surfactant coating having good lubricity and corrosion resistance is obtained on the magnetic metal thin film.

Next, examples of the present invention will be described.

Example 1 Oxygen was forcibly introduced onto a polyethylene terephthalate film (hereinafter referred to as PET film), and cobalt (
A ferromagnetic alloy thin film of nickel (80%') (20%) was fabricated by vacuum evaporation. An aqueous solution of potassium polyvinyl sulfate (manufactured by Wako Pongyaku Kogyo ■) having a concentration of 0.05 f/fl was applied to this ferromagnetic alloy thin film by dipping. Thereafter, it was washed with a large amount of pure water and then blown with dry air, the washing water was removed, and it was dried with hot air at 80C. The obtained magnetic thin film is referred to as sample A.

Example 2 Oxygen was forcibly introduced into a ferromagnetic alloy thin film of cobalt (80%) and nickel (20%) produced by vacuum evaporation on a PET film, and the polymeric surfactant Su7talence7on was applied to it. acid sodium formalin condensate (Kao Atlas■
An aqueous solution with a concentration of 1.oy7ρ (manufactured by Demol NJ) was applied by the dipping method, washed with a large amount of pure water, and then blown with dry air to remove the washing water and dried with hot air at 8oC. Sample B is the magnetic thin film prepared by the above method.

Example 3 Oxygen was forcibly introduced into a ferromagnetic alloy thin film of cobalt (80%) and nickel (20%) produced by vacuum evaporation on a PET film. Activator (manufactured by Hanaroku Atlas ■)
An aqueous solution of 0.1 f/ρ of Co (80% ) - A ferromagnetic alloy thin film of nickel (20%) was coated with an aqueous solution of sodium α-olefin sulfonate (Liporan 1400 J manufactured by Lion Oil Co., Ltd.), a polymeric surfactant, at a concentration of 0.03y/2 by dipping. After coating and washing with a large amount of pure water, dry air was blown to remove the washing water and the film was dried with hot air at 80 C. The obtained magnetic thin film was used as a sample.

Example 5 Oxygen was forcibly introduced and a-olefin sulfone, a polymeric surfactant, was applied to a cobalt (8Q%)-nickel (20%) ferromagnetic alloy thin film produced by vacuum evaporation on a PET film. An aqueous solution of sodium chloride (Soft Detergent WJ manufactured by Kao Atlas ■) with a concentration of o, o○29/fl was applied by the dipping method, washed with a large amount of pure water, and then blown with dry air and washed with washing water. 80C except
dried with hot air. The obtained magnetic thin film is designated as sample E.

Example 6 A ferromagnetic metal thin film of cobalt (80%) - nickel (20%) produced by vacuum evaporation on a PET film with forced introduction of oxygen was coated with sodium polyacrylate (synthesized by radical polymerization). obtained by saponifying polyacrylic acid)
An aqueous solution with a concentration of ○, o6y/min was applied by a dipping method, washed with a large amount of pure water, and dried air was blown to remove the washing water, followed by drying with hot air at 8oC. The obtained magnetic thin film is designated as sample F.

Water repellency of samples AF produced in Examples 1 to 6.

Corrosion resistance and lubricity were investigated. For comparison, an untreated sample was subjected to an environmental test at a C9 relative humidity of 90%, and lubricity was measured by measuring the coefficient of friction under a 10y load on a mirror-finished stainless steel 5US304 block.

The results are shown in the table below.

(Margin below) According to the present invention, the properties of the magnetic layer made of ferromagnetic metal are improved. In addition, the coefficient of friction is also reduced, making it possible to obtain a magnetic recording medium with excellent lubricity.

Claims (1)

[Claims] Sense recording medium. (2) The metal thin film magnetic recording medium according to claim 1, wherein the polymeric surfactant is water-soluble.