JPS61105725A - Magnetic disk - Google Patents

Abstract

PURPOSE:To obtain a magnetic disk having excellent thickness accuracy, surface accuracy and heat resistance by providing an underlying layer, magnetic layer and protective layer on a substrate formed by combining a plate-shaped body having excellent rigidity and heat resistance and a synthetic resin with which a specular surface characteristic is easily obtainable. CONSTITUTION:The composite substrate formed with an undercoating resin layer 2 and a synthetic resin layer 3 having a specular surface 3a on the layer 2 surface on one or both surfaces of the disk plate-shaped body 1 consisting of a metal such as Al or ceramic, etc. and having the excellent rigidity and heat resistance is manufactured. An epoxy resin is used for the layer 2 and an epoxy resin curable by an acid anhydride is used for the layer 3. The Ni-P underlying layer 4 is formed by electroless plating on the specular surface 3a of the composite substrate, then the Co-Ni-P magnetic layer 5 is formed thereon; thereafter the surface protective layer 6 is formed of SiO2, etc. on said layer. The specular surface 3a is obtd. by placing the substrate 1 provided with the layer 2 on a glass mold finished to the specular surface, casting an epoxy liquid resin to the mold and curing the resin by heat. The magnetic disk having the excellent heat resistance, surface accuracy, durability, etc. is thus obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic disk that has excellent surface accuracy, thickness accuracy, and rigidity by combining a synthetic resin and a plate-like body such as a metal plate. be.

[Prior art] Magnetic disks with good surface precision include those that use a glass plate, aluminum, metal plate such as Starbucks, or synthetic resin such as acrylic resin or epoxy resin as a substrate, and a magnetic layer is provided on the substrate. be. However, although it is possible to obtain extremely high surface precision in the case of glass substrates, it requires a polishing process that requires a large amount of man-hours to obtain this surface precision, and it also has drawbacks such as being easily broken and being sensitive to high temperatures. be.

In the case of metal substrates as well, a large number of man-hours are required for the polishing process to obtain surface precision. On the other hand, in the case of synthetic resin substrates,
By transferring from a mirror mold like a glass mold,
Although it is relatively easy to obtain excellent specularity,
There is a drawback in rigidity.

[Objective of the Invention] The present invention is a substrate with excellent surface precision, thickness precision, and rigidity by combining a rigid, heat-resistant, thin plate-like body with a synthetic resin that can easily obtain specularity. The object of the present invention is to provide a magnetic disk with excellent surface accuracy, thickness accuracy, rigidity, and heat resistance by providing a magnetic layer thereon.

"Configuration 1 of the Invention The present invention, as shown in FIG. mirror surface (3a)
This magnetic disk is characterized in that an underlayer (4), a magnetic layer (5), and a surface protection layer (6) are provided on a substrate made of a synthetic resin layer (3) having a base layer (4).

In the present invention, the plate-shaped body (1) is a metal plate such as an aluminum plate, a ceramic plate, a glass plate, or the like. Undercoat cedar 1 fat layer (2) formed on the surface of the plate-shaped body (1)
) is not particularly limited as long as it has excellent adhesion to the plate (1) and the synthetic resin layer (3), or may be geletane-based,
Epoxy resin is preferred.

The synthetic resin layer (3) formed on the undercoat layer has a mirror surface (3a). As synthetic resins, epoxy resins, urethane resins, and imide resins have heat resistance, hardness,
It is preferably used because of its excellent light resistance. In particular, epoxy resin is preferable in terms of the above-mentioned properties and moldability. Although any epoxy resin can be used, it is preferable to use an epoxy resin containing an acid anhydride curing agent, an amine curing accelerator, and, if necessary, an antioxidant, a light stabilizer, etc. due to the above-mentioned characteristics. In order to obtain a mirror surface on the surface of a synthetic resin layer, a casting method is generally used in which a plate is placed in a mirror-finished mold such as a glass mold, and the liquid resin is poured onto the plate. It is not limited to this. As the mold having a mirror surface, a glass mold or a mold with excellent surface precision is preferred because it is easy to obtain one. The thickness of this synthetic resin layer is usually about 0.02 to 0.5 nm.

In this way, a resin layer having surface precision comparable to that of a specular mold can be obtained. Since the thickness of this substrate is determined by the thickness of the molded part of the mold, it is possible to improve the thickness accuracy of the substrate by strictly specifying this thickness accuracy.

The underlayer and the magnetic layer may be of any type as long as they are normally provided on magnetic disks, and the method of providing these layers is not particularly limited. Preferably, it is formed. For example, in the case of sputtering, the underlayer is made of Cr and the magnetic layer is made of Co--Ni. In the case of electroless plating, the underlayer is formed of N1-P and the magnetic layer is formed of Co-N1-P. Furthermore, a surface protective layer such as ')Sin, etc. is now applied by a conventional method.

[Effect of the invention 1 In the present invention, the substrate has rigidity due to the plate-shaped body and excellent surface precision due to the synthetic resin, and also has excellent heat resistance and thickness accuracy due to the composite of the plate-shaped body and these 411 resins. Therefore, the magnetic disk of the present invention has excellent surface accuracy and disk thickness accuracy.

“Example” An example of the configuration shown in FIG. 2 will be described. Diameter 330
mm.

Aluminum plate with an inner diameter of 4.0 mm and a thickness of 1.6 mm (
1) Thickness 40 mm formed on both sides of the aluminum 1Kum board
μ'n epoxy 1 side I fatty undercoat 1 resin layer (2
) and a thickness of 100μ formed on the underfoot resin layer.
A substrate consisting of an acid anhydride-cured epoxy resin layer (3) of 10 μm in thickness and 10 μm in thickness, made into a shape I# by electroless plating.
M N1-P underlayer (4), 0.2 μm thick CoN1-P magnetic layer (5) formed by electroless plating, and 5
00A Si○.

This is a magnetic disk provided with a surface protective layer (6).

This magnetic disk was obtained as follows. Surface roughness with mirror finish on the inner surface 3Rmax0.01-0.0”2 J
im, using a glass mold with a flatness of 15 to 20 μm, placing an aluminum plate (1) with an undercoat resin layer (2) inside the mold, pouring the epoxy resin (liquid) into the mold, and heating at 90°C. hardened. Next, the underlayer, magnetic layer, and surface protective layer were formed on the substrate thus obtained.

The obtained magnetic support had the following characteristics.

Surface roughness Rmaxo, 01-0.02μm Flatness 15-20μm Disc thickness 1.9±0.02mm Heat resistance 180℃ Coercive force 6000e

[Brief explanation of drawings]

1 and 2 are cross-sectional views of the magnetic disk of the present invention. 1: Plate body 2: Undercoat, resin layer 3: Synthetic resin layer 3a: Mirror surface 4: Base layer 5: Magnetic layer 6: Surface protective layer -〇-

Claims (1)

[Claims] A circular plate-shaped body (hereinafter referred to as a plate-shaped body) such as a metal plate or a ceramic plate, an undercoat resin layer formed on both or one side of the plate-shaped body, and a synthetic resin having a mirror surface formed on the surface of the undercoat resin layer. A magnetic disk characterized in that a base layer, a magnetic layer, and a surface protective layer are provided on a substrate consisting of layers.