JPH0619832B2 - Magnetic memory - Google Patents

Description

The present invention relates to a magnetic memory used in a magnetic memory device (such as a magnetic disk device or a magnetic tape device) and a manufacturing method thereof.

(Prior Art and Problems Thereof) There are the following methods for recording / reproducing in a magnetic storage device that generally includes a recording / reproducing magnetic head (hereinafter referred to as a head) and a magnetic storage body. That is, after the head and the magnetic memory surface are set in contact with each other at the start of the operation, a space corresponding to an air layer is created between the head and the magnetic memory surface by applying a required rotation to the magnetic memory, and recording is performed in this state. This is a method of reproducing (contact start / stop method; hereinafter referred to as CSS method). In this method, the rotation of the magnetic storage body is stopped at the end of the operation, and at this time, the head and the surface of the magnetic storage body are in the contact friction state as at the start of the operation.

The frictional force generated between the head magnetic memory bodies in these contact frictional states may cause the head and magnetic memory bodies to rub and eventually cause damage to the head and magnetic medium. Further, in the contact friction state, a slight change in the posture of the head may make the load applied to the head non-uniform, and may scratch the surface of the head and the magnetic memory.

Further, the head and the magnetic memory body for a long time are contacted with each other and are attracted to each other, and are hard to separate. In order to prevent the generation and adsorption of the scratches, various side chain perfluoroalkyl polyethers or straight chain perfluoroalkyl polyethers having the following structures as shown in JP-A-52-498051 are conventionally used. The above lubricants have been proposed, but none of them have been able to prevent the generation of scratches on the magnetic storage body by repeating the CSS many times because the lubricant layer is gradually removed by CSS. In addition, the removed leaking lubricant is localized thickly on the contact sliding surface,
There is also a drawback that it causes adsorption to the head.

(Object of the Invention) An object of the present invention is to provide a magnetic storage body having a lubricant having excellent lubricating properties, less head adsorption, and good adhesion to the surface of the magnetic recording medium (that is, not deteriorating the head floating characteristics). To provide.

(Structure of the Invention) In the present invention, a magnetic medium is coated on a substrate, and the medium is directly or through a protective film, Comprising perfluoroalkyl compound to -CF ₂ -J- repeating units of the structure Alternatively, a magnetic storage medium having a structure in which a lubricating layer made of a mixture of the compound and a lubricant is coated, and a magnetic medium are coated on the underlayer, and the magnetic medium is coated directly or on the protective film. Through Having a functional group on at least one end of the structure consisting of --CF ₂ --J--
Perfluoroalkyl compound Alternatively, it is a magnetic memory having a structure in which a lubricating layer formed by mixing the compound and a lubricant is coated.

(Description of Configuration) Next, the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial cross-sectional view of a magnetic memory body according to the present invention. The base body 1 is made of aluminum alloy or anodized alumite, Ni-P plated film, Cr,
Aluminum alloy coated with FeNi, Mo or W, plastic such as polyester, polyimide, polyamide-imide, polysulfone, aromatic polyether, or Cr,
It is a metal such as FeNi, Mo, W, or a glass plate. Next, iron oxide such as Fe ₃ O ₄ , γ-Fe ₂ O ₃ or Co-Ni, Co-Ni-P, Co-Mn-P, Co as the magnetic medium 2 is formed on the base 1.
-Ni-Mn-P, Co-Re, Co-Mn-Re-P, Co-Ni-Mn-
Re-P, Co-Cr, Co-V, Co-Pt, Co-Ni-Pt, Co-Pt
It is coated with a metal or alloy such as --Cr, Co--Pt--V, Co--Rh, Co--Ni--Mo or Co--Sm. Further on the magnetic medium 2 Or a perfluoroalkyl compound having a functional group at one end or both ends and having -CF ₂ -J- as a repeating unit, or a lubricating layer 4 composed of a mixture of the compound and a lubricant. ing.

Used in the present invention An example of a perfluoroalkyl compound having a repeating unit of is a compound having the following structure. First, There is. However, Rf is C _l F _{2l + 1} (l is an integer of 1 or more, n is an integer of 5 or more), and J is Is a binding unit such as.

C ₁ F _{2l + 1} and Rf ′ are C ₁ F _2l (l is an integer of 1 or more, n is an integer of 5 or more, and G or G ′ is a functional group). Here functional groups G, G 'is _{-NCO, -SH, -SO 3 H,} -SO 3 M (M is Na,
K, any of Li), - CN, -NCS, -NO 2, _{-CONH 2, -I, COOH, -COOC} j H 2j + 1 (j is an integer of 1 or _{more), - C i H 2i OH} (i is 0 or an integer of 1 or more), NH _2, -
_{CH 2 = CH 2, -Si (} C h H 2h + 1) g X 3-g (h is an integer of 1 or more, g
Is 0, 1 or 2, X is Cl or -OH or OC _f H _{2f + 1} (f is 1
Or more)), or -A-S _i (C _h H _{2h + 1} ) _g X _3-g (h, g, X are the same as above. Also, A is C, H, N, O, S.
Of one or more elements).

For example _{-CO-NH-CH 2 -CH 2} , NH-CH 2 -CH (OH) -CH 2 -CH
_{2 -, - NH-CO-} CH 2 -CH 2 -, - O-CH 2 -CH 2 -, - S
-CH ₂ -CH _2, And so on.

Since the functional group G in the above general formula reacts strongly and adheres to the magnetic medium 2 or the protective film 3 formed on the magnetic medium 2 as shown in FIG. 2, it is not removed by the sliding of the head. .

This effect is -Si Among functional groups _{(C h H 2h + 1)} g X 3-1 (h is an integer of 1 or more, g is 0, 1 or 2, X is Cl or -OH, or
The silane represented by OC _f H _{2f + 1} (f is an integer of 1 or more) is most effective. In addition, -CF ₂ of the repeating unit in the main chain
Part of -J- Adsorbs and adheres to the magnetic medium 2 or the protective film 3 depending on the polarity of -J-. In this case, in the repeating unit Molecules have a function of more strongly adsorbing to the polar medium 2 or the protective film 3 more easily.

As described above, the structure or functional group of the repeating unit makes the fixation of the perfluoroalkyl compound to the protective film or the magnetic medium particularly strong.

Due to such strong fixing ability, two effects can be obtained at the same time, that is, the effect of sustaining lubricity to prevent scratches against sliding with the head and the effect of preventing adsorption of both due to reduction of cohesive force between the head and disk. To be The viscosity of the perfluoroalkyl compound is 10 to 10 depending on the molecular chain length and the type of functional group.
It can be changed up to 00000CPS.

An example of the lubricant mixed with the perfluoroalkyl compound 4 is Perfluoroalkyl polyether having a repeating unit, polytetrafluoroethylene, polytetrafluoroethylene telomer, perfluorocarboxylic acid, perfluoroalcohol, perfluorocarboxylic acid ester, fatty acid ester of perfluoroalcohol, perfluoroalkylalkoxysilane, Fluorosilicone, perfluoroalkyl sulfonic acid, ammonium perfluoroalkyl sulfonate, aliphatic alkylalkoxysilane, higher fatty acid, higher fatty alcohol, higher fatty acid ester, higher fatty acid amide fatty amine, unsaturated higher fatty acid, long chain aliphatic hydrocarbon , Polyalkylene glycol, silicone oil, polyoxyethylene, neopentyl polyol ester,
Examples include polyphenyl ether.

FIG. 2 is a partial sectional view of another magnetic memory body of the present invention. In FIG. 2, the underlayer 1, the magnetic medium 2, and the lubricating layer 4 made of a perfluoroarul compound having repeating units of —CF ₂ —J— or a mixture of the compound and a lubricant are the same as those in FIG. However, a protective film is coated between the magnetic medium 2 and the lubricating layer 4. The protective film 3 is SiO ₂ ,
Silicon compounds such as Si ₃ N ₄ , SiC or silicic acid polymer or
_{CoO, Co 3 O 4, Co} 2 O 3, α-Fe 2 O 3, Cr 2 O 3, CrO 3, TiO 2,
Or metal oxide such as ZrO ₂ or TiN, ZrN, CrN or TaN
Such as metal nitrides or metal carbides such as TiC, ZrC, CrC or TaC or W, Cr, Ir, NiP, Ru, Rh, Mn, Mo, Os
Alternatively, a metal or alloy such as Ta or an alloy thereof is used.

Both react well with the lubricating layer 4 and firmly
Can hold. Particularly, nickel oxide, cobalt oxide, or SiO ₂ has a remarkable effect.

After coating the lubricating layer 4, it may be baked at 100 to 300 ° C.

(Example) Next, the present invention will be described in detail with reference to examples.

Example 1 Surface roughness 0.02 μm coated with nickel-phosphorus plating film
A cobalt-nickel-phosphorus alloy as a magnetic medium 2 was plated to a thickness of 0.05 μm on a base body 1 mirror-finished to m. Next, a polysilicic acid (silicic acid polymer) as disclosed in JP-A-52-20804 is coated on the magnetic medium 2 as a protective film 3 by a spin coating method. Next, a lubricating layer 4 is formed on the protective film 3 and a perfluoroalkyl compound having a repeating unit of -CF ₂ -O- having the structure shown below is used. Was coated with a 0.1 wt% solution of tofluorotrichloroethane (hereinafter referred to as Cleon) by a spin coating method to prepare a magnetic disk. When this magnetic disk was evaluated by the evaluation method described below, it was confirmed that it had excellent durability.

Example 2 Same as Example 1, except that n = 20 to 3 as the lubricating layer 4.
0.05 wt% Freon solution of perfluoroalkyl compound to zero -CF ₂ -O- repeat units made magnetic disk using.

Example 3 A magnetic disk was prepared in the same manner as in Example 1 except that the lubricating layer 4 had a functional group at both ends of the structure shown below and a perfluoroalkyl compound having —CF ₂ —O— as a repeating unit was used. It was

Example 4 A magnetic disk was prepared in the same manner as in Example 3 except that the lubricating layer 4 had a functional group at both ends of the structure shown below and a perfluoroalkyl compound having a repeating unit of —CF ₂ —O—. It was

Example 5 Same as Example 3, except that the lubricating layer 4 has functional groups at both ends of the structure shown below, A magnetic disk was prepared using a perfluoroalkyl compound having a repeating unit of.

Example 6 A magnetic disk was manufactured in the same manner as in Example 3 except that a perfluoroalkyl compound having a functional group at one end of the structure shown below as a lubricating layer and having —CF ₂ —O— as a repeating unit was used. .

Example 7 A magnetic disk was prepared in the same manner as in Example 3, except that the lubricating layer 4 had a functional group at both ends of the structure shown below and a perfluoroalkyl compound having —CF ₂ —O— as a repeating unit was used. It was

Example 8 A magnetic disk was prepared in the same manner as in Example 3 except that the lubricating layer 4 had a functional group at both ends of the structure shown below and a perfluoroalkyl compound having —CF ₂ —O— as a repeating unit was used. It was

Example 9 A magnetic disk was prepared in the same manner as in Example 3, except that the lubricating layer 4 was a perfluoroalkyl compound having functional groups at both ends of the structure shown below and having —CF ₂ —O— as a repeating unit. .

Example 10 A magnetic disk was prepared in the same manner as in Example 3, except that the lubricating layer 4 was a perfluoroalkyl compound having functional groups at both ends of the structure shown below and having —CF ₂ —O— as a repeating unit. .

Example 11 A magnetic disk was prepared in the same manner as in Example 3 except that the lubricating layer 4 had a functional group at both ends of the structure shown below and a perfluoroalkyl compound having —CF ₂ —O— as a repeating unit was used. It was

Example 12 A magnetic disk was prepared in the same manner as in Example 3 except that the lubricating layer 4 was a perfluoroalkyl compound having functional groups at both ends of the structure shown below and having —CF ₂ —O— as a repeating unit. .

Example 13 A magnetic disk was manufactured in the same manner as in Example 3 except that the lubricating layer 4 was a perfluoroalkyl compound having a functional group at both ends of the structure shown below and having —CF ₂ —O— as a repeating unit. .

Example 14 Same as Example 1, except that NiP was used as the protective film 3 for the lubricating layer 4.
Is plated with 500Å and then baked at 280 ° C to form NiO on the surface.
To form a magnetic disk.

Example 15 Same as Example 3, except that the lubricating layer 4 and the protective film 3 were Si.
A magnetic disk was prepared by coating O ₂ with 200Å sputtering.

Example 16 Similar to Example 1, except that a CoCr alloy was coated as the magnetic medium 2 by a sputtering method, and a lubricating layer 4 having functional groups at both ends as in Example 3 and having —CF ₂ —O— was formed thereon. A magnetic disk was prepared by coating a perfluoroalkyl compound as a repeating unit.

Example 17 Similar to Example 16, except that γ-Fe ₂ O was used as the magnetic medium 2.
₃ was coated by a sputtering method to make a magnetic disk.

Example 18 A magnetic disk was manufactured in the same manner as in Example 1 except that the perfluoroalkyl compound having the following structure was used as the lubricating layer 4.

Example 19 A magnetic disk was prepared in the same manner as in Example 1 except that the perfluoroalkyl compound having the following structure was used as the lubricating layer 4.

Example 20 A magnetic disk was prepared in the same manner as in Example 1 except that the perfluoroalkyl compound having the following structure was used as the lubricating layer 4.

Example 21 A magnetic disk was manufactured in the same manner as in Example 1 except that the perfluoroalkyl compound having the following structure was used as the lubricating layer 4.

Comparative Example 1 A magnetic disk was prepared in the same manner as in Example 1, except that the protective layer 3 was coated with a perfluoroalkylpolyether having the following structure as the lubricating layer 4.

Comparative Example 2 A magnetic disk was prepared in the same manner as in Example 1, except that the protective film 3 was coated with a perfluoroalkylpolyether having the following structure as the lubricating layer 4.

The lubricating layers used in Examples 1-21 are shown in Tables 1-3.

Using the magnetic disks shown in Examples 1 to 21 and Comparative Examples 1 and 2, a head slider having an Al ₂ O ₃ .TiC core with a load of 15 g was used to repeat contact start stop (CSS) a number of times. When the wear test and the critical film thickness at which head adsorption started were measured, the results shown in the following table were obtained.

From the results in the above table, compared with the perfluoroalkyl polyethers of Comparative Examples 1 and 2, particularly Examples 1, 2, 14, 15, 1
It was found that the durability of the 8-21 perfluoroalkyl compound was remarkably improved. Further, it was found that the perfluoroalkyl compounds of Examples 3 to 13 have further durability. Since Examples 16 and 17 have no protective film, they have poorer durability than other Examples, but have better durability than Comparative Examples, and the critical film thicknesses of Comparative Examples 1 and 2 are also higher. Although the perfluoroalkyl polyether is young and the header adsorption starts even with a small film thickness, Examples 1, 2, 14, 15, 1
It was found that the 8 to 21 perfluoroalkyl compound did not cause head adsorption up to a thicker film thickness of 50 to 90Å and had a large margin. Furthermore, Examples 3 to 13 and 1
6,17 perfluoroalkyl compound is 90 ~ 150Å
Then, it was found that the critical thickness was further increased, and that head adsorption was less likely to occur.

It has a perfluoroalkyl polyether or one or both ends to a functional group having a -CF ₂ -O- repeat units shown in Examples 1 to 21 as described above (Effect of the Invention) The -CF ₂ -O- It has been found that perfluoroalkylpolyether as a repeating unit has excellent durability, is less likely to cause head adsorption, and can greatly improve the reliability of the magnetic disk device.

Although the magnetic disk is described in the embodiments of the present invention, it is obvious that the present invention is also effective for a floppy disk, a magnetic tape, and a magnetic card.

[Brief description of drawings]

1 and 2 are partial sectional views showing an example of the present invention. In the figure, 1 ... Substrate, 2 ... Magnetic medium, 3 ... Protective film, 4
…… It is a lubricating layer.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G11B 5/71 7215-5D // C10N 40:18

Claims (2)

[Claims] 1. A magnetic medium is coated on a substrate, and the medium is directly or through a protective film, Comprising perfluoroalkyl compound to -CF ₂ -J- repeating units of the structure A magnetic memory having a structure in which a lubricating layer made of is coated. 2. A magnetic medium is coated on a substrate, and the magnetic medium is coated on the medium. Elephant has a functional group G or G ', perfluoroalkyl compounds with repeating units -CF ₂ -J- A magnetic memory having a structure in which a lubricating layer made of is coated.