JP2884641B2 - Magnetic recording media - Google Patents

Description

The present invention relates to a magnetic recording device, for example, a magnetic recording medium used for a magnetic hard disk device, a magnetic tape device, a floppy disk device, a magnetic card device, and the like.

2. Description of the Related Art Magnetic recording devices include a magnetic hard disk device, a magnetic tape device, a floppy disk device, a magnetic card device, and the like. It is considered a magnetic hard disk drive. At present, in the case of a magnetic hard disk, a magnetic recording device using a floating magnetic head is a contact start type.
Whether the stop method (hereinafter referred to as CSS method) occupies the mainstream of the start / stop method. In this CSS method, the recording / reproducing magnetic head (hereinafter referred to as head) contacts the surface of the magnetic recording medium when the disk rotation starts / stops. I do. As a result, the head comes into sliding contact with the surface of the magnetic recording medium, and the head and the surface of the magnetic recording medium are worn, the coefficient of friction between the two increases,
In severe cases, the head may be destroyed (crashed). Therefore, in order to avoid such problems,
A lubricating layer using a liquid lubricant such as perfluoroalkyl polyether having an ether bond is formed on a protective film typified by carbon or silicon dioxide mainly composed of graphite on the magnetic layer. This layer is commonly used, and the durability of a several-stage magnetic recording medium is improved by providing this layer. However, the durability was not yet satisfactory. Accordingly, a partially fluorinated alkyl lubricant has been proposed as a new lubricant (Japanese Patent Application Laid-Open No. 62-219314).

Problems to be Solved by the Invention By the way, the use of the magnetic recording device is used in all parts of the world. Therefore, depending on the region, there are environmental conditions of high temperature and high humidity, high temperature and low humidity, low temperature and high humidity, and low temperature and low humidity, and stable durability must be exhibited in all of these environmental conditions.

However, partially fluorinated alkyl-based lubricants show sufficient durability under normal environment or high temperature or high humidity, but at low temperature or low humidity, the adhesion strength to the substrate is reduced and durability is slightly deteriorated. Can be On the other hand, in the case of a perfluoroalkyl polyether, although the durability is lower than that of the partially fluorinated alkyl-based lubricant under the normal environment, the deterioration of the durability is extremely small even at low temperature and low humidity compared with the normal environment. . However, in the case of perfluoroalkyl polyether, there is a problem that durability is deteriorated by the influence of water in a high humidity environment.

Means for Solving the Problems In the present invention, a mixture containing at least a partially fluorinated alkyl-based lubricant represented by Formula (1) or Formula (2) and a perfluoroalkyl polyether is used for a lubricating layer.

Action With this configuration, the properties of the partially fluorinated alkyl-based lubricant and the perfluoroalkyl polyether represented by the formula (1) or (2) can be utilized.

Examples Hereinafter, examples will be described with reference to the drawings. FIG. 1 is a diagram showing a basic configuration of a magnetic recording medium according to one embodiment of the present invention. In the figure, 1 is a non-magnetic support, 2 is a ferromagnetic metal thin film, 3 is a corrosion-resistant protective film, 4 is a carbon protective film,
5 is a mixed lubricating layer containing a perfluoroalkyl polyether and a partially fluorinated alkyl-based lubricant represented by the formula (1) or (2). The perfluoroalkyl polyether used in the mixed lubricating layer 5 and the partially fluorinated alkyl-based lubricant represented by the formula (1) or (2) are represented by the following chemical structures as representative chemical structures. Product name KR made by DuPont with a chemical structure
YTOX143 series.

In addition, the same product name 157 series manufactured by DuPont FOMBLIN Z series, Y series, AM200 manufactured by Mondigison
1, Demnum SP, SA manufactured by Daikin Industries, Ltd., and the like.
Among them, any perfluoroalkyl polyether alone or a mixture may be used. Particularly, the average molecular weight is suitably from 1,000 to 8,000, more preferably from 2,000 to 6,000. When the average molecular weight is 1000 or less, the vapor pressure becomes high, and it is easy to volatilize at high temperature, and the durability is deteriorated. When the average molecular weight is 8000 or more, the viscosity increases and the abrasion resistance is improved, but the frictional force is increased and stick slip occurs, the durability is deteriorated, and the magnetic recording medium is unsuitable.

On the other hand, those used as partially fluorinated alkyl-based lubricants have the formula (1)
It is represented by the general formula shown in (2).

In the formulas (1) and (2), Rf and R'F represent a fluoroaryl terminal group or a fluoroalkyl terminal group having 3 or more carbon atoms, a phenylene group having 6 or more carbon atoms or a derivative thereof, or an aliphatic group having 1 or more carbon atoms. Represents a fluorinated hydrocarbon bonded directly or via an oxygen atom or a sulfur atom to a hydrocarbon chain consisting of an alkylene group, and specific examples thereof include, for example, a fluoroalkyl terminal group. (However, n represents an integer of 3 or more.) As a fluoroaryl terminal group Etc.

R represents a hydrocarbon chain composed of an aliphatic alkyl terminal group having 8 or more carbon atoms, or a phenylene group having 6 or more carbon atoms or a derivative thereof. (However, n represents an integer of 8 or more.) As a hydrocarbon terminal group consisting of a phenylene group or a conjugate with a derivative thereof (However, p represents an integer of 0 to 4, m represents an integer of 1 or more, and n represents an integer of 8 or more.).

_{(Z) m} and (Z _{') m'} is - [O- (CH _{2) n} -] _m - [S- (CH _{2) n} -] _m - [COO- (CH _{2) n} -] _m (Where m and m 'are 0 or 1, n is 0 or an integer of 1 or more, and R represents H, CH ₃ or C ₂ H ₅ ). as (Where n is an integer of 1 or more, R represents H, CH ₃ , or C ₂ H ₅ ) (Where, n represents. 0 or an integer of 1 or more) represents a bonding chain selected from the polar group-terminated X is selected -OR, -SH, -COOH, -COSH, among -CONH ₂ Or a mixture of these organic compounds with other generally known lubricants, rust inhibitors and the like.

The mixing ratio of the perfluoroalkyl polyether and the partially fluorinated alkyl-based lubricant represented by the formula (1) or (2) can be any environment when used at a mixing ratio of about 1: 9 to 7: 3 by weight. No deterioration in lubrication characteristics is observed under the conditions. In particular, if the mixing ratio of the perfluoroalkyl polyether is too high, the effect of the partially fluorinated alkyl-based lubricant represented by the formula (1) or (2) is lost. Even if the mixing ratio is small, the properties of the perfluoroalkyl polyether are not lost and sufficient durability can be obtained.

As a coating method, both the perfluoroalkyl polyether and the partially fluorinated alkyl-based lubricant represented by the formula (1) or the formula (2) are mixed with an alcohol or Freon 113 at a mixing ratio determined within the above range. After being dissolved in an organic solvent, it is applied to a magnetic recording medium by a method such as spraying, dipping, and spin coating. The coating amount is preferably 0.5 to 500 mg / m ² , but it cannot be said unconditionally because the appropriate film thickness is determined by the surface roughness of the magnetic recording medium. If the coating amount is too small, the frictional force increases and the wear increases, and stable durability cannot be obtained. Conversely, if the coating amount is too large, a sticking phenomenon (adsorption) between the recording / reproducing head and the magnetic recording medium occurs, and the durability is deteriorated.

The samples prepared in this manner were each subjected to environmental conditions A to C.
A CSS test was performed to determine the maximum value of the dynamic friction coefficient after 20,000 times of CSS. Among these, the environmental conditions B and C are said to be very severe environmental conditions in the operating range of the magnetic recording / reproducing apparatus currently used.

A: 20 ° C. 50% RH B: 5 ° C. 20% RH C: 65 ° C. 80% RH The CSS test results of each of the above samples are shown in Table 1 in comparison with the contents of the samples.

As is clear from the results in Table 1, each embodiment of the present invention has a small dynamic friction coefficient at room temperature and normal humidity (condition A), low temperature and low humidity (condition B), and high temperature and high humidity (condition C) and is extremely stable. Shows durability. Further, from the results of the comparative examples, the perfluoroalkyl polyether alone (Comparative Example 1) or the partially fluorinated alkyl-based lubricant alone (Comparative Example 2) had a μ at a high temperature and high humidity (C condition) and a low temperature and low humidity (B condition), respectively. Rise. By providing a layer in which the perfluoroalkyl polyether and the partially fluorinated alkyl-based lubricant represented by the formula (1) or (2) are provided, a lower coefficient of dynamic friction is exhibited at a low temperature and a low humidity than those of the individual layers. Shows unique properties. Furthermore, the provision of the mixed lubricating layer shows a stable and low dynamic friction coefficient under all environmental conditions, so that the torque applied to the motor for driving the magnetic recording medium is constant in any environment, so that a load is imposed on the motor. I can do it.

Magnetic recording media prepared by applying a layer in which a perfluoroalkyl polyether and a partially fluorinated alkyl-based lubricant represented by the formula (1) or (2) are mixed to a metal thin film tape are similarly A to C. It has been confirmed that the device exhibits stable still characteristics under the following environmental conditions.

Effect of the Invention According to the present invention, a perfluoroalkylpolyether and a partially fluorinated alkyl-based lubricant represented by the formula (1) or (2) are formed as a lubricating layer, whereby a perfluoroalkyl Since the polyether and the partially fluorinated alkyl-based lubricant represented by the formula (1) or (2) are uniformly mixed and exhibit properties superior to both properties, each of the above lubricants can be obtained alone. It has become possible to obtain stable abrasion resistance and friction resistance over a wide temperature range and humidity range of a magnetic recording device that cannot be obtained. In addition, when the magnetic recording apparatus is not operating, the head and the magnetic recording medium come into contact with each other, so that the lubricant is diffused into a gap generated between the head and the magnetic recording medium, particularly, liquid lubricated perfluoroalkyl polyether, and the sticking phenomenon ( However, in the case of the present invention, since the solid partially fluorinated alkyl-based lubricant represented by the formula (1) or (2) is mixed, the diffusing power of the perfluoroalkyl polyether is suppressed, This has the effect of reducing the sticking phenomenon (adsorption). According to the invention of this mixed lubricant, a magnetic hard disk,
It has been applied not only to magnetic tapes but also to floppy disks and magnetic cards, making it possible to greatly contribute to the reliability of magnetic recording devices for high recording densities.

[Brief description of the drawings]

The drawing is an enlarged sectional view of a main part in one embodiment of the magnetic recording medium of the present invention. DESCRIPTION OF SYMBOLS 1 ... Nonmagnetic support, 2 ... Ferromagnetic metal thin film, 3 ... Corrosion-resistant protective film, 4 ... Carbon protective film, 5 ... Mixed lubricating layer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 5/71 G11B 5/71 5/72 5/72 // C10N 40:18 (58) Fields surveyed (Int.Cl. ⁶ G11B 5/62-5/82 C10M 105/54 C10M 105/68 C10M 105/72 C10N 40:18

Claims (1)

(57) [Claims] 1. A magnetic recording medium comprising a magnetic layer provided on a substrate and a lubricating layer provided on the magnetic layer, wherein the lubricating layer has the following formula (1): Or the following equation (2) A magnetic recording medium using a mixture containing a partially fluorinated alkyl-based lubricant and a perfluoroalkyl polyether represented by the formula: [In the formula, Rf and R'f represent a hydrocarbon group comprising a fluoroaryl terminal group or a fluoroalkyl terminal group having 3 or more carbon atoms, a phenylene group having 6 or more carbon atoms or a derivative thereof, or an aliphatic alkylene group having 1 or more carbon atoms. Represents a fluorinated hydrocarbon bonded to a chain directly or via an oxygen atom or a sulfur atom. R is an aliphatic alkyl terminal group having 8 or more carbon atoms,
Alternatively, it represents a hydrocarbon chain comprising a phenylene group having 6 or more carbon atoms or a derivative thereof. (Z) m and (Z ') m' is - [O- (CH ₂₎ n-] m or - [O- (CH ₂₎ n-] m '- [S- (CH ₂₎ n-] m or - [S- (CH ₂₎ n-] m '- [COO- (CH ₂₎ n-] m or - [COO- (CH ₂₎ n-] m' - [CON- (CH ₂ ) n-] m, or - [CON- (CH ₂₎ n-] m ' (Where m and m ′ are 0 or 1, n is 0 or an integer of 1 or more, and R represents H, CH ₃ or C ₂ H ₅ ). Y is (Where n represents 0 or an integer of 1 or more). X represents -OH, -SH, -COSH, a polar group-terminated selected from among -CONH _2. ]