JPS59129956A - Production of optomagnetic recording medium - Google Patents

Abstract

PURPOSE:To form a recording layer which has excellent vertical magnetic anisotropy and is stable by subjecting a cleaned and dried acrylic resin substrate to a heat treatment in a specific vacuum degree to remove the org. gas. etc. in the substrate then forming an optomagnetic recording layer. CONSTITUTION:A cleaned and dried acrylic resin plate is heat-treated for >=1hr in a range of 70-85 deg.C at <=10<-4>Torr vacuum degree. The resin plate freed of the org. gas incorporated therein in the above-mentioned way is used as a substrate and, for example, GdTbFe thin layer or the like is sputtered on the surface of such substrate to form an optomagnetic recording layer. The deterioration in vertical magnetic anisotropy on account of the gas released from the inside in the stage of forming the recording layer is thus prevented and the recording medium which permits thermomagnetic recording and magnetooptical reproducing of information and has excellent recording sensitivity and durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a rewritable high-density recording medium in which information is recorded thermomagnetically and reproduced magneto-optically. The recording medium includes a non-magnetic substrate supporting a recording layer having perpendicular magnetic anisotropy.

Conventional Structure and Problems Conventionally, in manufacturing magneto-optical recording media, a recording layer has been formed directly on an acrylic resin substrate after cleaning and drying by sputtering or vapor deposition. but,
The perpendicular magnetic anisotropy of the formed recording layer is poorer than that of a glass substrate, and its deterioration is also rapid.

Also, between the acrylic resin substrate and the recording layer, 5102 or A
If a layer such as /= is provided for protection, there is a drawback that the effect is insufficient or the recording sensitivity decreases.

OBJECTS OF THE INVENTION The present invention provides a method for manufacturing a magneto-optical recording medium in which a recording layer having excellent perpendicular magnetic anisotropy and stability is formed on the surface of an acrylic resin substrate.

Structure of the Invention The present invention provides for cleaning and drying an acrylic resin substrate at 70°C.
This is a method for producing a magneto-optical recording medium, in which a recording layer is formed after heat treatment for one hour or more at a temperature of ~85° C. and a vacuum of 10 Torr or less.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

The substrate is an acrylic plate and a glass plate with ioo ~ 20
A GdTbFe thin film was formed as a recording layer on the substrate surface by sputtering using a substrate provided with a 0 μm thick kotoeki radiation hardening acrylic resin layer. FIG. 1 shows the magnetization curve in the perpendicular direction in the plane of the recording layer when the recording layer is directly formed on the substrate after washing and drying as in the prior art. In the magneto-optical recording medium prepared by the conventional method, the perpendicular magnetic anisotropy of the recording layer is poor.
It is unsuitable as a recording medium. This is thought to be because the organic gas contained in the acrylic resin is released by the heat during sputtering or vapor deposition, is incorporated into the recording layer, and has an adverse effect on its magnetism.

In this example, the cleaned and dried substrate is placed in a vacuum evaporation machine.
Place it under a vacuum of 10-4 Torr or less and heat it to 60°C.
After heat treatment at temperatures of 70° C.+85° C. for 1 to 4 hours, a GdTbFe thin film was formed as a recording layer on the substrate surface by sputtering.

FIG. 2 shows the change over time in the squareness ratio of the magnetization curve in the direction perpendicular to the plane of the recording layer of the medium produced under the above conditions.

By heat-treating at 70° C. or higher for 1 hour or more, a recording layer having almost perfect perpendicular magnetic anisotropy was obtained. Unfortunately, since the heat resistance of acrylic resin is low at temperatures above 90°C, the substrate would be noticeably deformed, making it unsuitable.

Note that when the substrate was heat-treated in a low vacuum of 10-3 TOrr or more, the perpendicular magnetic anisotropy of the formed recording layer was insufficient, and its deterioration was faster than when heat-treated in a high vacuum.

Effects of the Invention By using the method for producing a magneto-optical recording medium of the present invention, a recording layer with excellent perpendicular magnetic anisotropy and excellent stability can be formed on an acrylic resin substrate. As a result, it has become possible to use a substrate with tracking guide grooves formed on the acrylic resin surface, and it has become possible to produce a magneto-optical recording medium having a random access function, which is highly effective.

[Brief explanation of the drawing]

FIG. 1 shows a magnetization curve recorded perpendicularly to the plane of the recording layer of a magneto-optical recording medium manufactured by a conventional manufacturing method, and FIG. 2 shows a magneto-optical recording medium manufactured by an embodiment of the present invention. FIG. 3 is a diagram showing the change over time in the squareness ratio of the magnetization curve in the direction perpendicular to the surface of the recording layer of FIG. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 2 0 /234 Retsusho Shiojibun (A)

Claims (1)

[Claims] A method for manufacturing a magneto-optical recording medium in which a recording layer is formed on the surface of a substrate made of acrylic resin, the substrate being heated at a temperature of 70° C. to 85° C. and a vacuum of 1 O-4 Torr or less for 1 hour or more before forming the recording layer. 1. A method for manufacturing a magneto-optical recording medium, comprising heat treatment.