JPS61283030A - Magnetic disk medium - Google Patents

Abstract

PURPOSE:To improve the durability, resistance to head clash and S/N of a coated film of the title medium by incorporating two kinds of Al2O3 having respectively different particle diameters into the magnetic coated film in a specified volume ratio. CONSTITUTION:A magnetic paint is obtained by dispersing particles of nonmagnetic alumina in a resin along with gamma-Fe2O3, Co-coated gamma-Fe2O3 powder, Fe-Co alloy powder and Ba ferrite powder. Al2O3 particles having 0.05-0.2mum mean particle diameter and angular Al2O3 particles (having protrusions) are mixed in 19/1-15/5 volume ratio and 0.5-5wt%, based on the total volume of the coated film, mixture is incorporated. Since two kinds of Al2O>=3 particles having respectively different particle diameter are mixed in the above-mentioned ratio and the function of reinforcing the coated film is shared between the two kinds of particles having respective size, the defects of the medium and noise are remarkably reduced. Consequently, a disk coating film having excellent durability, resistance to head clash and S/N is obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a magnetic disk medium, in particular, a disk-shaped non-magnetic substrate such as an aluminum alloy, in which magnetically enriched iron powder, non-magnetic particles, etc. are placed in a resin and a solvent. This invention relates to a magnetic disk medium coated with a dispersed magnetic paint.

[Conventional technology]

Conventionally, magnetic disk coatings include r-Fe2 in resin.
O3 or CO deposited r-Fe2O. Dispersed magnetic particles such as AQ2O3 particles and AQ2O3 particles are used to obtain the mechanical strength of the coating film. The particle size of this incoming 2O3 is 0
．． The diameter is 5 to 1 μm, the shape is spherical or rice grain-like, there are no corners on the surface, and the volume content is 1 to 10%.

[Problem that the invention seeks to solve]

In general, from the viewpoint of the mechanical strength of the coating film, ■ The sliding between the magnetic head floating surface and the disk surface when the disk starts and stops rotating.

■Dust adheres to the head floating surface during disk rotation, disrupting the stable floating state of the head, and causing damage to the coating film due to contact between the coating film and the head, so-called head clarity.

The coating must be able to withstand sufficient resistance to In order to improve this durability, in the conventional technology, it is necessary to increase the amount of AJ2O3 mixed or to increase the particle size. On the other hand, from the viewpoint of signal-to-noise ratio (8/N), AllzOa particles, which are non-magnetic particles, are the main cause of media noise generation, and it is desirable to reduce the amount of mixed particles and reduce the particle size. As described above, it is currently impossible to fully satisfy both coating film durability and S/N ratio.

[Means for solving problems]

According to the invention r-Fe, 03, = rbalt (Co)
Deposited r-Fe2O3 iron oxide powder, Fe-Co alloy powder.

In a disk coating film coated with a magnetic paint in which barium (Ba) ferrite powder, etc. and alumina (AlzOa), which is a non-magnetic particle, is dispersed in a resin, the average particle diameter is 0.0.
A, 92O3 particles with an average particle diameter of 5 to 0.2 μm and an angular (containing convex portion) Afiz with an average particle diameter of 0.4 to 1 μm.
Os particles at a volume ratio of 19:1 to 15 [Principle of the invention] That is, the present invention mixes two types of AjhO3 with different particle sizes into the coating film at a predetermined ratio, and
By having Os particles share different roles in strengthening the paint film, we are able to achieve superior paint film durability that could not be achieved with conventional technology.
It has a high S/N ratio.

As a magnetic paint applied as a magnetic disk.

r-Fe2O3 or Co-coated r-Fe2O3 magnetic particles, and Al12OB fine particles with an average particle size of 0.05 to 0.2 μm as A92O3 particles to obtain coating strength.
0,4 with a relatively large particle size and angular burrs on the surface.
~I Am 0A1zOs t - Mixed at a volume ratio of 19:1 to 15:5 so that the volume content is 0.5 to 5% based on the coating film volume when forming the coating after coating and baking. The mixture is dispersed in a resin and a solvent, applied onto a substrate, and after baking, the surface is polished to form a coating film.

Here l! As an effect of 2Oa particles on coating strength.

One is a kind of catalytic effect that promotes the polymerization reaction of the resin during paint film baking and improves the strength of the resin itself.The other is that its high hardness bears the contact load when the head makes contact, and the paint film surface Alz with upwardly protruding angular burrs
Os may have a significantly large self-cleaning effect on the head floating surface.

For the former purpose, it is desirable that a large number of fine particles of AfLzoat be dispersed in the resin so that the contact area with the resin is large. For the latter purpose, it is desirable to use AJlzOs, which has a grain size approximately equal to the thickness of the coating film and has angular burrs.

In this way, two types of Afi2O3 particles with different particle sizes are mixed into the coating film at a predetermined ratio, and the Afi2O3 particles of each size are assigned different roles in strengthening the coating film. Since defects and large particles that increase noise can be significantly reduced compared to conventional media, the S/N ratio is improved.

Therefore, coating film durability, head crush resistance, and S/N
A disc coating film with excellent properties can be obtained.

〔Example〕

Next, examples of the present invention will be described. The composition of the disk coating film is as shown in Table 1. Magnetic powder, Al12
A magnetic paint was prepared by cross-dispersing O3 particles in a resin and a solvent, and this was applied onto a chromate-treated aluminum alloy substrate by a spin cord method.
Baking treatment for 2 hours at °C and polishing to achieve a coating thickness of 0.55
Finished to µm and applied lubricant to the disk surface. The two types of Al2O3 have a small particle size with an average particle size of 0.
0.5μm1 If the particle size is large and square, use 0.5μm.

Example Table 1 FIG. 1 shows the cross-sectional structure of the disc coating of the present invention.

As a comparative example, magnetic paints were prepared having disk coating compositions as shown in Tables 2 and 3, and a lubricant was applied to the finished disk surface in the same manner as described above to a coating thickness of 0.55 μm.

Comparative Example 1 Table 2 Comparative Example 2 Table 3 FIG. 2 shows the cross-sectional structure 1- of the disk coating film of Comparative Example 1, and FIG. 3 shows the cross-sectional structure of the disk coating film of Comparative Example 2.

Figure 4 shows a contact start-stop (C, 8, 8) test in which the rotation of the disk is started and stopped repeatedly in an atmosphere with a cleanliness level of class 100 or below, and the disk surface and magnetic head flying surface are repeatedly slid. , shows the number of C, S, and S times until the paint film becomes scratched.

Also, Figure 5 shows the results of a seek test in which the head continuously reciprocated at high speed from the outer circumference to the inner circumference of the disk.

The relative speed between the disk and the head is 40 m/sec, the flying height of the magnetic head is 0.15/jm, and the seek speed is 3 m/sec.
5lle.

The cleanliness of the atmosphere is below class 100 and class io,
In the case of ooo or more, the number of seeks until the paint film becomes scratched is shown.

FIG. 6 shows the signal-to-noise ratio at a recording density of 400 FRPI (flux reversal/inch). C0S,S
The coating strength for the test was 35,000 times or more for the medium of the present invention, and 15,000 to 41.0 times for the comparative medium, Comparative Example 1.
00 times, and 26.000 to 42.00 in Comparative Example 2. ooo times 1
, the coating strength for the seek test is class 100.
14. The medium of the present invention was prepared in the following atmosphere. OO0 times or more, 10,000 to 22,000 times in Comparative Example 1 of comparative medium,
In Comparative Example 2, it was 11,500 to 20,000 times, and in an atmosphere of class 10,000 or higher, the inventive medium
0,000 to 125,000 times, 15. OO0 to 134000 times, 50 in Comparative Example 2,
000~iao, ooo times.

On the other hand, 8/N is 29.3 to 30.9 dB for the medium of the present invention.

Comparative Example 1 and Comparative Example 2 were 26.1 to 28.7 dB and 26.3 to 28.4 dB, respectively.

From the above results, the disk media of Examples according to the present invention had the same or superior coating film durability and head scratch resistance compared to Comparative Examples. It has excellent signal-to-noise ratio.

〔Effect of the invention〕

As explained above, one aspect of the present invention is Al2 for strengthening the coating film.
O, AJh03f with different particle sizes and shapes as particles: By mixing each AlzOs with a different role of strengthening the coating film, the durability of the coating film is maintained on a par with conventional methods, while achieving excellent f. :, S/Nt- can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a cross section of a disk coating film in an example of the present invention, FIG. 2 is a schematic diagram of a cross section of a disk coating film in Comparative Example 1, and FIG. 3 is a schematic diagram of a cross section of a disk coating film in Comparative Example 2. FIG. 4 is a diagram showing the results of the C, S, and S tests, and shows the number of times C, S, and S caused scratches on the coating surface. FIG. 5 is a diagram showing the seek test results, and shows the number of times of seeking that causes scratches on the coating film surface. FIG. 6 is a diagram showing the signal-to-noise ratio at a recording density of 400 FRPI (magnetic flux reversal/inch). 1...
...magnetic particles, 2... large particles with angle υ 12O3.3... small spherical Al particles
zOs, 4... Resin, 5... Nonmagnetic substrate, 6... Large spherical particles of AizOs. Sikh Mohammedanism (times) (?,,S,S-S-number (Lola

Claims (1)

[Claims] γ-Fe_2O_3, cobalt (Co) coated γ-Fe_
2O_3 iron oxide powder, Fe-Co alloy powder, barium (B
a) Ferrite powder etc. and alumina (Al which is a non-magnetic particle)
In the disk coating coated with magnetic paint in which _2O_3) is dispersed in resin, the average particle size is 0.05 to 0.2μ.
m Al_2O_3 particles and an average particle diameter of 0.4 to 1
Contains angular (having convex portions) Al_2O_3 particles with a volume ratio of 19:1 to 15:5 with a volume content of 0.5% to 5% of the total coating film volume. A magnetic disk medium characterized by: