JPS6233335A - Production of magnetic disk medium - Google Patents

Abstract

PURPOSE:To improve long-period stability by coating an epoxy silane compd. on the surface of an inorg. compd. film then bringing the epoxy silane compd. and the inorg. compd. forming the inorg. compd. film into condensation reaction. CONSTITUTION:After the epoxy silane compd. 3 is coated on the surface of the inorg. compd. film 2, the epoxy silane compd. 3 and the inorg. compd. forming the inorg. compd. film 2 are brought into condensation reaction. The epoxy silane compd. film 3 fixed to the inorg. compd. film by a chemical bond is formed. The epoxy silane compd. forming such epoxy silane compd. film, etc. and a lubricating agent contg. a carboxyl group or carboxylate group are brought into ring opening addition reaction in the presence of a basic catalyst to form the chemical bond between the epoxy silane compd. and the lubricating agent, by which the lubricating agent film 5 fixed by the chemical bond onto the epoxy silane compd. film is formed. The ring opening addition reaction is effected in a short period at a low temp. of about 100 deg.C to form the lubricating agent film 5. The high-performance lubricity is thereby stably maintained for a long period of time.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a method for forming a lubricant film for a magnetic disk medium by covalently bonding the lubricant to an inorganic compound film on a magnetic film via an epoxysilane compound. By letting and fixing the length j
The present invention relates to a method of manufacturing a magnetic disk medium that forms a highly stable lubricant film.

<Prior art> In general, the contact start φ stop method (C
SS method) is mainly adopted. In the C5S method, when starting or stopping operation, the head and the magnetic disk surface are brought into contact, and the required rotation is given to the magnetic disk, giving the head a flying blade and forming an air layer between the magnetic disk surface and the head. , perform recording and playback in this state.

Therefore, abrasion during contact and changes in the posture between the magnetic disk and the head cause the load applied to the head to become uneven, which may cause scratches on the surfaces of the head and the magnetic disk. Also, depending on the type of lubricant or the amount of lubricant applied is too large, the adsorption force between the head and the magnetic disk may become abnormally large.
Therefore, when the rotation starts or stops, there is a possibility that a head crash will occur, which will destroy the head and damage the surface of the magnetic disk. Furthermore, during recording and reproduction, the head suddenly comes into contact with the magnetic disk medium, and a large frictional force acts between the head and the magnetic disk medium, often resulting in destruction of the head and the magnetic disk medium. In order to prevent this phenomenon and protect the head and magnetic disk medium, a lubricating layer is formed on the surface of the magnetic film.

As the lubricant layer, the following lubricant layer is conventionally formed to lubricate a sputter disk. That is, an inorganic silicon compound film is provided on a magnetic film, and a perfluoropolyether (for example, trade name Krytx 143AC or AD, Fonprin YR,Z), which is a fluorinated carbon lubricant, or a carboxyl group-containing perfluorinated perfluoropolyether is provided on the magnetic film. Fluoropolyether (e.g. trade name Krytx 157FS)
) or applied silicone oil.

<Problems to be solved by the invention> However, when using perfluoropolyether or silicone oil, these lubricants migrate from the center of the magnetic disk medium to the outer periphery when the magnetic disk medium rotates at high speed, resulting in a decrease in the lubricant film thickness. This causes the wear between the head and the magnetic disk medium mentioned above.

There is a problem that head crashes, collisions, etc. cannot be effectively prevented. Furthermore, by using fluorinated polyether containing carboxyl groups, the inorganic silicon compound and the carboxyl groups are bonded by weak hydrogen bonds, which makes it difficult for the fluorinated polyether containing carboxyl groups, which is a lubricant, to be fixed to the surface of the magnetic disk medium. Not enough is done;
Therefore, it was not possible to prevent the lubricant from disappearing due to evaporation. Also, uneven lubricant film thickness occurs during high-speed rotation.

Therefore, it has not been possible to effectively prevent damage to the head and magnetic disk medium due to wear and collision.

In order to solve the above problems, the present inventors previously proposed a magnetic disk medium in which a lubricant was chemically fixed to the magnetic disk surface via an epoxysilane compound (Japanese Patent Application No. 59-57453). ), this magnetic disk medium is obtained by ring-opening and reacting an epoxysilane compound film chemically bonded (covalently bonded) with an inorganic silicon compound through a condensation reaction with a lubricant containing a carboxyl group in its chemical structure. It has a lubricant film fixed by chemical bonds. The reaction between the epoxysilane compound film and the carboxyl group-containing lubricant is carried out by means such as heating.

Usually, the reaction temperature is set at 150 to 250 to accelerate the reaction.
A method is being used to raise the temperature to ℃.

However, even with the method of increasing the reaction temperature, the reaction between the epoxysilane compound film and the carboxyl group-containing lubricant is very slow, so the carboxyl group-containing lubricant is thermally decomposed or evaporated before it is fixed on the magnetic disk. The carboxyl group-containing lubricant is often scattered from the surface of the magnetic disk, and therefore the carboxyl group-containing lubricant is not sufficiently fixed onto the magnetic disk, making it difficult to obtain desired lubricating properties.

Therefore, the present invention provides a magnetic disk medium in which the above-mentioned lubricant film having excellent long-term stability can be easily and completely formed by promoting the reaction between the above-mentioned epoxysilane compound and the carboxyl group-containing lubricant. The purpose is to provide a manufacturing method.

<Means for Solving the Problems> The present invention achieves the above object in a method for manufacturing a magnetic disk medium in which an inorganic compound film is formed on the surface of a magnetic film. After applying the compound, the epoxysilane compound and the inorganic compound forming the inorganic compound film are subjected to a condensation reaction to form a lubricant containing an epoxysilal group or a carboxylic acid ester moiety fixed to the inorganic compound film through a chemical bond. A lubricant film fixed by chemical bonds on the epoxysilane compound film is formed by forming a chemical bond between the epoxysilane compound and the lubricant by performing a ring-opening addition reaction with the lubricant in the presence of a base catalyst. It is characterized by forming.

Here, as the inorganic compound film formed on the magnetic film,
Silicon oxide film (main component 5i02) is most widely used, but other materials include oxides of titanium, aluminum, zirconium, magnesium, tungsten, bismuth,
carbides, nitrides, boron.

compounds, or mixtures thereof.

In the present invention, first, a monomolecular to several molecular layer of an epoxysilane compound is coated on such an inorganic compound film, and the above inorganic compound and the epoxysilane compound are subjected to a dehydration condensation reaction to form a chemical bond with the inorganic compound film. Form an epoxysilane compound film. This reaction occurs even at room temperature10
The reaction will proceed more reliably if heated to 0 to 200°C.

The epoxysilane compound used here is represented by the following general formula.

Specific examples of the epoxysilane compound include the following compounds. As the aliphatic epoxysilane compound, an example of n=o in the general formula is γ-glycidoxypropyltrimethoxysilane.

γ-Glycidoxyprobyltriethoxysilane.

β-glycidoxyethyltrimethoxysilane.

Examples include β-glycidoxyethyltriethoxysilane. In the general formula, those with n=1 include γ-glycidoxypropyl methyldimethoxysilane, γ-glycidoxypropyl methyljethoxysilane, β-glycidoxyethylmethyldimethoxysilane, β-glycid Examples include xyethylmethyljethoxysilane. Furthermore, as the alicyclic epoxysilane compound, n in the general formula
= 0 examples include β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-diboxycyclohexyl]ethyltriethoxysilane, γ-(
Examples of the general formula n=1 include β-(3,4-epoxycyclohexyl)
Ethyldimethoxymethylsilane, β-(3,4-epoxycyclohexyl)ethyljethoxymethylsilane, γ
Examples include, but are not limited to, -(3,4-epoxycyclohexyl)propyldimethoxymethylsilane, γ-(3,4-epoxycyclohexyl)propyljethoxymethylsilane, and the like.

The hydrolyzate of such an epoxysilane compound undergoes a dehydration condensation reaction with, for example, a silanol group of an inorganic silicon compound to form a 5i-0-3i bond, and the reaction formula at this time is as follows.

Ep S+OH+HOSi〈→Ep-Si O9+4 On the other hand, the above-mentioned lubricant used in the present invention has a carboxyl group, a carboxylic acid ester moiety, a sulfonyl group, etc. that undergo a ring-opening reaction with the epoxy group of the above-mentioned epoxysilane compound as part of its molecular structure. Examples include carboxyl group-containing perfluoropolyethers, carboxyl group-containing silicone polymers, carboxylic acid ester moiety-containing perfluoropolyethers, and sulfonyl group-containing perfluoropolyethers. Incidentally, the carboxyl group, carboxylic acid ester moiety, sulfonyl group, etc. may be contained at one end and both ends of the lubricant, or in the middle of the repeating unit of the polymer.

By using such a lubricant, it is possible to form a lubricant film that is fixed to the above-mentioned boxysilaso compound film through chemical bonds. Moreover, in the present invention, since the ring-opening/addition reaction between the epoxysilane compound and the lubricant is promoted by a base catalyst, the lubricant film can be easily formed even at room temperature. Of course, one reaction can be further promoted by heating to around 100°C.

The base catalyst may be applied by (1) applying the base catalyst on the epoxysilane compound film and then applying the above-mentioned lubricant, or (2) applying the above-mentioned lubricant to which the base catalyst has been added in advance to the epoxysilane compound film. This may also be done by coating on the membrane.

FIG. 1 is an explanatory diagram of the implementation of method (2), and FIG. 2 is an explanatory diagram of method (2). In both figures, 1 is a magnetic film, 2 is an inorganic compound film, 3 is an epoxysilane compound film, 4 is a base catalyst layer, 5 is a lubricant layer, and 6 is a lubricant layer to which a base catalyst is added.
By applying the basic catalyst and lubricant onto the epoxysilane compound film 3 in this manner, a lubricant film chemically bonded to the epoxysilane compound film 3 is quickly formed.

Typical base catalysts used in the present invention include tertiary amines such as triethylamine and tripropylamine, but are not limited thereto. This a again! The amount of the base catalyst added is preferably equal to or 2 to 5 times the equivalent of the reactive group such as a carboxyl group or carboxylic acid ester moiety in the lubricant.

The above-mentioned epoxysilane compound, lubricant, base catalyst, and lubricant to which the base catalyst is added may be applied by a spin code method, a dipping method, a spray method, a wiper method, or the like.

Function> In the present invention, the base catalyst first reacts with the carboxyl group of the lubricant. As an example of this, the reaction between a trialkylamine and a carboxyl group is shown below.

When the carboxyl group reacts with the trialkylamine in this way, it becomes an ionic ammonium salt, which is more likely to react with the epoxy group in the epoxysilane compound film than the carboxyl group itself. In this way, the reaction between the epoxysilane compound and the lubricant proceeds rapidly, and a lubricant film fixed to the epoxysilane compound film through chemical bonds is formed.

<Examples> Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 FIG. 3 is a sectional view of a magnetic disk medium formed according to this example. As shown in the figure, an alumite layer 8 is formed on both sides of an aluminum layer 7, and an inorganic compound film 9 made of 5i02 is formed on a mirror-polished disk substrate. A monomolecular to several molecular layer of hydrolyzate of γ-glycidoxypropyltrimethylsilane (or γ-glycidoxypropyldimethoxymethylsilane) is formed on the surface of the inorganic compound film 9, and heated at around 100°C. By heating for several hours, this hydrolyzate and the silanol groups of the inorganic compound film 9 undergo a dehydration condensation reaction to form siloxane bonds. In this way, an epoxysilane compound film 10 chemically bonded to the inorganic compound film 9 is formed.

Next, on this epoxysilane compound gto, a layer of carboxyl group-containing perfluoropolyether as a lubricant and triethylamine as a base catalyst is formed by 8 to 20 people. FIG. 4 shows the orientation state of the lubricant and the epoxysilane compound at this time. Here, triethylamine reacts with the carboxyl group of the lubricant to form quaternary ammonium ions lla.

Next, by heating at 100°C for 2 to 3 hours, a ring-opening/addition reaction rapidly proceeds between the quaternary ammonium ion lla and the noepoxy group of the epoxysilane compound, resulting in a covalent bond ( A lubricant film 11 fixed to the epoxy silane compound film 10 by chemical bonding is formed. At this time, triethylamine used as a base catalyst is volatilized by heating and does not remain on the surface of the magnetic disk.

The change in lubricant film thickness when the magnetic disk medium according to this example was aged in an oven at 150°C was
Figure 7 shows the changes in the friction coefficient.

For comparison, a magnetic disk medium having a lubricating layer according to the prior art was also aged in the same way. The decrease in lubricant film thickness was very small, and the friction coefficient remained stable without fluctuation for more than one month.

In addition, the magnetic disk medium according to this embodiment has a load of 8g.
Contact start/stop using Mn-Zn ferrite Winchester type slider (C
5S) In the test, even after 70,000 cycles of C3S, no wear marks or wear particles were observed on the magnetic disk or magnetic head, and they continued to rotate normally.

Example 2 Sputtering method (
β-(3,4-epoxycyclohexyl) is applied to the surface of a magnetic disk on which a 5i02 film is formed using
A monomolecular to several molecular layer film of ethyltrimethoxysilane (or β-(3,4-epoxycyclohexyl)ethyldimethoxymethylsilane) is formed. Thereafter, this silane compound is subjected to a hydrolysis reaction to form an epoxysilane compound film that is covalently bonded to the 5i02 film. 8 by spin-coding (or dipping) polyether
Apply to a constant film thickness for up to 25 people. Here, by heating at around 100°C for 2 to 3 hours, a covalent bond is formed between the epoxysilane compound and the carboxyl group-containing perfluoropolyether through a ring-opening/addition reaction. In this way, a lubricant film fixed to the epoxysilane compound film through covalent bonds is formed. At this time, the tertiary amine used as a base catalyst catalytically promotes the ring-opening reaction of the epoxy group by forming a strongly ionic ammonium salt with the carboxyl group in the lubricant, and then It becomes more volatile.

The lubricant film thickness of the magnetic disk medium manufactured in this manner did not decrease for 30 days after aging at 200°C, and the magnetic disk medium and slider (manufactured by Altic, Winchester type tapered flat head, The coefficient of friction with respect to the load (9 gr) was 0.25 or less for both static friction and dynamic friction, and remained constant and did not fluctuate during the aging test at 150° C. for 130 days. In addition, as a result of conducting C5S tests 60,000 times before and after this aging, there were no wear marks or wear particles on the magnetic disk media or magnetic heads, and they showed normal rotation.
No deterioration from the initial value was observed in the recording and playback characteristics.
It showed high reliability.

Example 3 Using γ-glycidoxyprobyltriethoxysilane as an epoxysilane compound, 5i02 of the magnetic disk
After a monomolecular to several molecular layer film is formed on the film, it is hydrolyzed to produce an epoxysilane compound film with siloxane bonds formed between it and the 5i02 film.

Application of this epoxy silane compound is applied to the epoxy silane compound.

This is carried out by exposing the magnetic disk to the vapor of the silane compound, by spin-coding a dilute solution of the epoxy silane compound, by dipping the disk, or the like.

Next, Jt! is applied onto the epoxysilane compound film. The group catalyst triethylamine is spin-coded, followed by spin-coding a solution of the carboxyl group-containing perfluoropolyether in a fluorinated solvent to a thickness of 10 to 25 people. Thereafter, the mixture is heated at 80° C. for 2 hours to react the epoxysilane compound and the carboxyl group-containing perfluoropolyether to form a covalent bond.

The friction coefficient of the magnetic disk medium of this example formed in this way was measured using the same slider as in Example 2.
A 5S test was conducted. As a result, the friction coefficient was 0.25 or less, and no variation from the initial value was observed even after aging for 150'0.50 days.

Further, even after 60,000 cycles of the C3S test, no friction marks or friction particles were observed on the head or magnetic disk medium, and no performance deterioration in read or write characteristics was observed.

Example 4 β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane as an epoxysilane compound is coated on the 5i02 film of a magnetic disk by a spin code method to form a sublayer film for a period of time ranging from a single molecule to several minutes.Afterwards... By heating to around 100° C. for several hours, a siloxane bond is formed between S+02 and the epoxysilane compound.

Next, a carboxylic acid methyl ester moiety-containing perfluoropolyether to which tripropylamine has been added in advance is applied onto the epoxysilane compound film, and heated at 100°C.
Heat for about 2 hours back and forth. Thus, a ring opening/addition reaction occurs between the carboxylic acid methyl ester moiety and the epoxy group,
'A lubricant film (perfluoropolyether) is formed that is fixed to the epoxysilane compound film by covalent bonds.

The magnetic disk medium thus formed exhibited excellent characteristics similar to those of Example 1.

<Effects of the Invention> As explained above in detail with the examples, according to the method of the present invention, a lubricant film is fixed to an inorganic compound film such as 5i02 of a magnetic disk by chemical bonding via an epoxysilane compound film. Therefore, there is no decrease in film thickness over a long period of time under high temperatures, no increase in friction coefficient, and no deterioration of C3S characteristics. Of course, the friction coefficient at this time is low, and the C8S characteristics are also excellent with over 50,000 cycles. There is. In addition, in the method of the present invention,
By coexisting a basic catalyst such as a tertiary amine in the reaction system of an epoxysilane compound and a lubricant containing a carboxyl group, this ring-opening/addition reaction can be carried out in a short time at a low temperature of around 100°C. A lubricant film having these properties can be easily formed.

Furthermore, the magnetic disk medium manufactured by the method of the present invention can stably maintain high-performance lubricity for a long period of time under high-speed rotation without uneven distribution of lubricant or evaporation of scattered documents. Therefore, the magnetic disk medium can run, record and reproduce with high reliability over a long period of time.

[Brief explanation of the drawing]

Figure m1 and Figure 2 are explanatory diagrams showing an embodiment of the method of the present invention,
FIG. 3 is a cross-sectional view of a magnetic disk medium obtained by an embodiment of the present invention, FIGS. 4 and 5 are explanatory diagrams showing the orientation state of compounds in the embodiment, and FIG. 6 is a lubrication during aging. FIG. 7 is a graph showing changes in the agent film thickness over time, and FIG. 7 is a graph showing changes over time in the coefficient of friction during aging. In the drawing. 1 is a magnetic film, 2 is an inorganic compound film, and 3 is an epoxysilane compound film. 4 is a base catalyst layer, and 5 is a lubricant layer. 6 is a lubricant layer to which a base catalyst is added; 7 is an aluminum layer. 8 is an alumite layer. 9 is an inorganic compound film, and 10 is an epoxysilane compound film. 11 is a lubricant film.

Claims (1)

[Claims] 1) A method for manufacturing a magnetic disk medium in which an inorganic compound film is formed on the surface of a magnetic film, in which an epoxysilane compound is applied to the surface of the inorganic compound film, and then the epoxysilane compound and the inorganic compound are mixed together. An epoxysilane compound film fixed to the inorganic compound film through chemical bonds is formed by a condensation reaction with an inorganic compound forming the film, and the epoxysilane compound forming the epoxysilane compound film and a carboxyl group or carboxylic acid ester The epoxysilane compound is fixed on the epoxysilane compound film by chemical bonding by forming a chemical bond between the epoxysilane compound and the lubricant by performing a ring-opening addition reaction with the lubricant containing the above in the presence of a base catalyst. 1. A method of manufacturing a magnetic disk medium, comprising forming a lubricant film. 2) The method of manufacturing a magnetic disk medium according to claim 1, wherein the lubricant film is formed by applying the base catalyst on the epoxysilane compound film and then applying the lubricant. 3) The method of manufacturing a magnetic disk medium according to claim 1, wherein the lubricant film is formed by applying the lubricant to which the base catalyst has been added in advance onto the epoxysilane compound film. 4) The inorganic compound film is an oxide, a nitride, a carbide,
A method for manufacturing a magnetic disk medium according to claim 1, using a boronide. 5) The method of manufacturing a magnetic disk medium according to claim 1, wherein a carboxyl group-containing perfluoropolyether or a carboxyl group-containing silicone polymer is used as the lubricant.