JPS5939807B2 - magnetic memory - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage body used in magnetic storage devices (magnetic disk devices, magnetic drum devices, etc.).

In general, there are two types of recording/reproducing methods for a magnetic storage device including a recording/reproducing magnetic head (hereinafter referred to as a head) and a magnetic storage body, as follows.

The first method is to set the head and the magnetic storage surface in contact at the start of operation, and then apply a required rotation to the magnetic storage to create an air layer between the head and the magnetic storage surface. This is a method of creating a space and recording and playing in this state. In this method, the rotation of the magnetic storage body stops at the end of the operation, and at this time the head and the surface of the magnetic storage body are in the same frictional state as at the start of the operation. The second method is to apply a required rotation to the magnetic storage body in advance, and then suddenly press the head onto the surface of the magnetic storage body.
This method creates a space equivalent to an air layer between itself and the magnetic storage surface, and records and plays in this state. Thus, in the first method, the head and the magnetic storage surface are in a frictional contact state at the start and end of the operation, and in the second method, the head and the magnetic storage surface are in a frictional contact state when the head is pressed against the magnetic storage surface. The frictional force generated between the head and the magnetic storage body in these contact friction states causes wear on the head and the magnetic storage body, and may eventually cause scratches on the head and the metal magnetic thin film medium. Further, in the contact friction state, a slight change in the posture of the head may cause the load applied to the head to become uneven, causing scratches on the surface of the head and the magnetic storage body. Furthermore, it often happens that the head suddenly comes into contact with the magnetic storage body during recording and reproduction, and a large frictional force acts between the head and the magnetic storage body, causing the head and the magnetic storage body to be destroyed. Such contact friction between the head and the magnetic storage body,
To protect the head and magnetic storage from contact wear and damage, it is necessary to coat the surface of the magnetic storage with a protective coating. Conventionally, there has been a method of coating a metal plating film (for example, Cr.Rll.Ni-P, etc.) as a protective film, or a force method of oxidizing the surface of a metal magnetic thin film medium to form an oxide to form a protective film. However, none of these methods is effective against the above-mentioned contact friction phenomenon. The present inventor has already proposed a protective film made of polysilicic acid that eliminates these drawbacks (Japanese Patent Application No. 81201/1982). This protective coating made of polysilicate can sufficiently withstand the contact friction between the head and the magnetic memory, and can also withstand sudden contact of the head with the magnetic memory for more than 30 minutes. It has sufficient properties as a protective film, such as sufficiently protecting the thin film and not impairing the magnetic properties of the underlying metal body including the magnetic storage body. However, some heads tend to draw dust between the head and the magnetic memory, and this dust acts as an abrasive and wears down the head and the magnetic memory, and the abrasion powder generated by that abrasion is Additionally, there are some that cause wear to the head and magnetic storage.

This phenomenon is more pronounced in heads with a tapered front. SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic storage body having a protective coating that sufficiently protects the metal magnetic thin film medium even from the above-mentioned heads that tend to attract dust.

The magnetic memory of the present invention includes a mirror-polished nonmagnetic disk-shaped substrate coated with a metal magnetic thin film medium, and a polysilicate film containing a chain polymer compound having a functional group coated on the metal magnetic thin film medium. It consists of

Furthermore, the magnetic memory of the present invention is constructed by coating a metal magnetic thin film medium on a mirror-polished non-magnetic disk-shaped substrate, and coating the metal magnetic thin film medium with a polysilicate film containing a silane coupling agent. Ru. Next, the present invention will be explained in detail with reference to the drawings. The drawing is a sectional view showing an embodiment of the magnetic storage body of the present invention. In the drawings, a magnetic storage body 5 of the present invention includes an alloy disk 1 and a non-magnetic alloy layer 2 coated thereon.
a non-magnetic disk-shaped substrate composed of a metal magnetic thin film medium 3 coated on the polished surface of the non-magnetic alloy layer 2, and a chain polymer compound having a functional group on the metal magnetic thin film medium 3. A protective coating 4 made of polysilicic acid containing . Further, the protective coating 4 of the magnetic memory of the present invention is made of a polysilicate coating containing a silane coupling agent instead of a chain polymer compound having a functional group.

The alloy disk 1 must be finished with a surface having sufficiently small waviness (50 μm or less in the circumferential force direction and 100 ttm or less in the radial force direction).

This is because if the waviness is large, the head floating above the magnetic storage medium cannot follow the vertical movement of the magnetic storage surface during recording and playback, and the distance between the head and the magnetic storage medium changes.
This is because the recording/reproducing characteristics change. The non-magnetic alloy metal destroyed by plating on this alloy disk 1 is mirror-refinished to a surface roughness of 0.04 μm or less by mechanical polishing. Note that if the alloy disk 1 is made of a metal that can be mirror-polished, the non-magnetic alloy layer 2 is not necessary. A metal magnetic thin film medium 3 for high-density recording is coated on the non-magnetic l alloy layer 2 by plating. The protective coating 4, which sufficiently protects the metal magnetic thin film medium 3 from head contact or changes due to moisture or temperature, is made of a linear polymeric compound having a functional group or polysilicic acid containing a silane coupling agent. The above-mentioned functional group is one that reacts with the silanol group SiOH in polysilicic acid and has the effect of strongly bonding with polysilicic acid. Refers to N-methoxymethyl-modified nylon methylcellulose, ethylcellulose, or a combination thereof. Silicone intermediate has an average molecular weight of 500-2
A polymer compound consisting of approximately 000 Si and O chains.
It has a functional group such as OH or SiOCH3. Also,
N-methoxymethyl modified nylon is a nylon resin having a methoxymethyl group -CH2OCH3 as a functional group. Methyl cellulose and ethyl cellulose are cellulose resins having a methoxy group -0CH3 and an ethoxy group -0C2H3, respectively. On the other hand, a silane coupling agent is a type of silane compound represented by the following general formula. RcSi(Xa)n(Xb)3, :n is an integer of 0 to 3, and in the formula, Xa and Xb are halogen atoms such as Cl or Br, or 0Rd or 0C0R
d (Rd is, for example, CH3, C2H5?:
? =? 367”CH3OOCCH2CH2NH(CH2
)2NH(CH2), represents a part consisting of an organic substance having a functional group such as.

Xa and Xb are silanol groups Si-0H by hydrolysis
will occur. Examples of such silane coupling agents include:

In addition, although the chemical formula is not clear, the units +÷- -N-+ are repeated in the RC part to form 1st class, 2nd class,
Also included are polyaminosilanes in which tertiary organic groups each having one step are complexly branched to form the following matrix.

Next, the present invention will be explained in detail by giving Examples and Comparative Examples.

Example 1 The alloy disk 1 was made with sufficiently small waviness (50% in the circular force direction and in the radial direction) by lathe machining and thermal straightening.
A nickel-phosphorus (Ni-P) alloy is plated to a thickness of approximately 50 μm as a non-magnetic alloy layer 2 on a disk-shaped aluminum alloy substrate whose surface has been finished with a surface of 10 μm or less. After the plating film is mechanically polished to a mirror finish with a surface roughness of 0.04 μm or less and a thickness of about 30 μm, a cobalt-nickel-phosphorus (CO-Ni-P) alloy is coated on top of it as a metal magnetic thin film medium 3. ．．
It was plated to a thickness of 0.05 μm.

Furthermore, this cobalt nickel monophosphorus (CO-Ni-P
) After thoroughly mixing a solution with the composition shown below on the alloy film, 500
A magnetic disk was obtained by baking a disk-shaped disk coated to the thickness of A in an electric furnace at a temperature of 200° C. for 3 hours.
゜Example 2 A magnetic disk was obtained by firing a disc-shaped disc coated using the same force method as in Example 1, but using a solution having the composition shown below, under the same conditions as in Example 1.

Example 3 A magnetic disk was prepared by firing a disk-shaped disk coated using the same force method as in Example 1, but using a solution having the composition shown below, under the same conditions as in Example 1.

Example 4 A magnetic disk was obtained by coating a disk-shaped disk using the same method as in Example 1, but using a solution having the composition shown below, and firing it under the same conditions as in Example 1.

Example 5 A magnetic disk was prepared by firing a disk-shaped disk coated using the same force method as in Example 1, but using a solution having the composition shown below, in the same manner as in Example ψu1.

Example 6 A magnetic disk was prepared by baking a disk-shaped disk coated in the same manner as in Example 1 using a solution having the composition shown below under the same conditions as in Example 1.

Example 7 A disk-shaped disk coated using the same force method as in Example 3 using a solution having the same composition was baked at 150° C. for 5 hours to obtain a magnetic disk.

Example 8 A magnetic disk was obtained by coating a disk-shaped disk in the same manner as in Example 1, but using a solution having the composition shown below, and firing it under the same conditions as in Example 1.

Example 9 A disk-shaped disk was coated using the same force method as in Example 1, but using a solution having the composition shown below, and fired under the same conditions as in Example 1 to obtain a magnetic disk.

Comparative Example A magnetic disk was prepared by baking a disk-shaped disk coated in the same manner as in Example 1 using a solution having the composition shown below and under the same conditions as in Example 1.

Using each of the magnetic disks shown in Comparative Example and Examples 1 to 9, in a recording/reproducing force method in which the head and the magnetic disk surface are always in contact at the start and end of operation,
This operation start and end operation test was repeated for 5,000 times using a head with a tapered front part to easily pull in dirt.
When the test was repeated several times, about 5% of the friction marks on the head of the magnetic disk of Comparative Example were peeled off, but no peeling was observed for each of the magnetic disks of Examples 1 to 9.

Furthermore, in Examples 5 and 6, there was no peeling even after 10,000 repetitions. In addition, Examples 4, 7,
No. 8 and 9 showed no peeling even after 15,000 repetitions. As shown in the comparative examples and Examples 1 to 9 above, magnetic disks with a protective coating made of polysilicic acid containing a chain polymer compound having a functional group or a silane coupling agent have a protective coating made of polysilicic acid alone. It can be seen that the wear resistance of the head is improved compared to that of the magnetic disk.

Furthermore, it is found that the wear resistance of magnetic disks having a protective coating made of polysilicic acid containing a silane coupling agent having a particularly large molecular weight or a large Rc among silane coupling agents has significantly improved wear resistance. The effects of the silane coupling agent or the chain polymer compound having a functional group contained in the protective coating of the magnetic data star of the present invention are considered to be due to the following reasons.

That is, polysilicic acid, which is one of the components of the protective coating, is formed by condensation polymerization of tetrahydroxysilane 7.
It is a three-dimensional network polymer consisting of repeating -0 bonds,
Internal stress is generated in this polysilicic acid film due to volume reduction due to solvent evaporation or polymerization, or due to a difference in thermal expansion coefficient with the underlying body, and the resulting distortion weakens the original strength of the polysilicic acid.

When a silane coupling agent is added to this polysilicic acid, the portion R containing a functional group contained in the silane coupling layer 1 is
The silanol group generated by hydrolysis of c, Xa, and To improve the contact wear resistance of a protective coating made of polysilicic acid containing a coupling agent to the head.
This magnetic disk contains a silane coupling agent with Rc made of a flexible organic substance with a molecular weight of 100 or more, and has a protective coating made of polysilicic acid with greater stress relaxation ability.The magnetic disk has further improved wear resistance against the head. I understand from this.

Furthermore, when a chain-linked polymer compound having a functional group is added to polysilicic acid, the silanol group (Si-0H) of the polysilicic acid reacts with the functional group, and finally forms a covalent bond with the network structure of the polysilicic acid. The flexible chain parts of the polymer compound alleviate the stress caused by the shrinkage of the polysilicic acid and increase the strength of the polysilicic acid. Improves contact wear resistance. It should be noted that the magnetic memory having a protective coating made of a linear polymer compound containing a functional group or polysilicic acid containing a silane coupling agent according to the present invention has higher wear resistance than a magnetic memory having a protective coating made only of polysilicic acid. Although improved, other performances as a magnetic memory material, such as head crush resistance, lubricity, environmental resistance, and magnetic properties of the underlying metal body, remain unchanged.

Note that it is clear that polymer compounds other than those shown in the present invention can be used as long as they have the function of relieving stress in the polysilicate film.

Further, in the examples, n-butyl alcohol was used as the solvent, but other solvents may be used as long as they dissolve both tetrahydroxysilane and the chain polymer compound having a functional group or the silane coupling agent. Therefore, it is clear that linear polymeric compounds or silane coupling agents having other functional groups that are not soluble in alcohol can also be used as stress relievers.

Further, in the comparative examples and examples of the present invention, metal was used as the non-magnetic disc-shaped substrate, but it is clear that plastic or the like can also be used, and the type of the substrate is not limited.

[Brief explanation of drawings]

The figure is a sectional view of the magnetic storage body of the present invention.

Claims (1)

[Claims] 1. A metal magnetic thin film medium is coated on a mirror-polished non-magnetic disk-shaped substrate, and a polysilicate film containing a chain polymer compound having a functional group is coated on the metal magnetic thin film medium. A magnetic memory. 2. The magnetic memory according to claim 1, wherein the chain polymer compound having a functional group is a silicone intermediate. 3. The magnetic memory according to claim 1, wherein the chain polymer compound having a functional group is N-methoxymethyl-modified nylon. 4. The magnetic memory according to claim 1, wherein the chain polymer compound having a functional group is methylcellulose, ethylcellulose, or a mixture thereof. 5. A magnetic memory comprising a mirror-polished non-magnetic disk-shaped substrate coated with a metal magnetic thin film medium, and a polysilicate film containing a silane coupling agent coated on the metal magnetic thin film medium. 6. The magnetic memory according to claim 5, wherein the silane coupling agent contains an organic substance having a molecular weight of 100 or more. 7 The silane coupling agent is polyaminosilane or N
-Beta(aminoethyl)-gamma-aminopropyltrimethoxysilane. The magnetic memory according to claim 5.