JP2001143253A - Magnetic recording medium and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having a lubricating film provided with low friction and excellent wear resistance and water repellency by improving a bond rate without executing treatment after application of a lubricant. SOLUTION: This magnetic recording medium has the lubricating film formed by applying the lubricant on the surface of the medium after irradiation with UV rays. This lubricant is a perfluoropolyether compound which has a benzene ring at its terminal group and preferably contains a piperonyl group in this terminal group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a hard disk used in a magnetic recording / reproducing device used as an external storage device of a computer, and more particularly to a low friction, abrasion resistance and water repellency. The present invention relates to a magnetic recording medium having improved reliability.

[0002]

2. Description of the Related Art In recent years, the demand for higher density of magnetic storage / reproducing devices such as disk drive devices used in computers has been rapidly increased in recent years, and the capacity and density have been further increased. In response to such a demand, the magnetic spacing between the magnetic head on the disk drive device main body side and the hard disk as the magnetic recording medium disposed therein is reduced, that is, the interval is reduced as much as possible. It is necessary.

FIG. 1 shows a conventional disk drive device 100.
Magnetic head 120 and rotating hard disk 1
FIG. 2 is a diagram schematically showing a relationship between the hard disk and the hard disk; FIG. Hard disk 11
No. 0 has a basic structure in which a base film 113 and a magnetic film 115 are sequentially stacked from the bottom on a substrate 111, and a carbon-based protective film such as a DLC (Diamon) is formed thereon.
d Like Carbon) 117 is formed.

By the way, the disk drive device 10
0, a contact start and stop (CSS: Contact Start and Stop) in which the air bearing surface 120a of the magnetic head 120 contacts and slides on the surface of the hard disk 110 when the hard disk 110 starts and stops rotating.
Stop) system is employed. In the CSS method, a CSS area is provided as an area where the hard disk 110 and the magnetic head 120 are in contact with each other. Hard disk 11
To start rotation of the hard disk 1, the magnetic head 120 is
It travels in contact with 10 CSS areas. Then, the magnetic head 120 floats by the airflow generated by the rotation of the hard disk 110.

However, an unexpected contact failure may occur while the magnetic head 120 is flying, and the magnetic head 120 may come into contact with the hard disk 110. Further, when the hard disk 110 starts and stops rotating, the magnetic head 120 always contacts the CSS area of the hard disk 110. Therefore, it is necessary to keep the surface of the hard disk 110 in a state of low friction and wear resistance.

For this reason, the conventional hard disk 110
A lubricating film 119 formed by further applying a lubricant is provided on the protective film 117 on the surface. Lubrication film 1
Reference numeral 19 greatly affects the friction and wear characteristics of the hard disk 110, and thus plays an important role in ensuring the reliability of the disk drive device 100. Further, the role of the lubricating film 119 is not limited to the above. The disk drive device 100 is used in various environments. When the disk drive device 100 is used under high temperature and high humidity, the hard disk 110 or the magnetic head 120 may be corroded due to dew condensation or absorbed water under the influence of the atmospheric humidity. Therefore, the lubricating film 119 has an important role of uniformly applying a lubricant having water repellency on the hard disk 110 to prevent corrosion of the hard disk 110 or the magnetic head 120 and to prevent water and dust from adhering. I also carry.

[0007] It is expected that further lowering of the space will be promoted in the future, and it is even more important to maintain the hard disk 110 to have low friction, wear resistance and water repellency over a long period of time by a lubricating film. Becomes However, in general, the temperature inside the disk drive device 100 becomes high, and the hard disk 110 rotates at high speed. Therefore, the lubricating film 1
In many cases, the lubricant forming No. 19 moved to the peripheral portion of the hard disk 110 with time due to the centrifugal force and then separated from the hard disk 110. Therefore, the lubricating film 119 on the hard disk 110 becomes thinner with time. As described above, when the thickness of the lubricating film 119 is reduced, the function of the lubricating film to maintain the surface of the hard disk at a state of low friction, wear resistance and water repellency is lost.

In order to prevent such a situation, it is necessary to form the lubricating film 119 using a lubricant having a stronger attraction to the hard disk 110. Here, focusing on the relationship between the protective film 117 on the surface of the hard disk 110 and the lubricating film 119 formed thereon, in the lubricating film 119, a bond layer (bonding layer) firmly bonded to the surface of the protective film 117. ) 119a,
The mobile layer (Mobile Layer) which detaches when receiving an external force such as a centrifugal force due to a weak bonding force with the surface of the protective film.
r) 119b is known to be present. As described above, the reason why the lubricating film 119 on the hard disk 110 becomes thinner is that the mobile layer 119b is
It is considered that the main cause is that the disk moves to the periphery of the disk 10 and then separates from the hard disk 110.

Therefore, the disk drive device 100
In order to keep the thickness of the lubricating film 119 close to the initial thickness even after the use and the passage of time, the protective film 117 is required.
Of the bond layer 119a that has a strong adsorbing power (bond ratio)
Should be increased. Therefore, the bond layer 1
Various attempts have been made to increase 19a.
In these conventional techniques, first, a lubricant is applied onto the protective film 117 of the hard disk 110, and the applied lubricant (lubricating film) 119 is subjected to ultraviolet irradiation or heat treatment to increase the bond ratio. And

[0010]

However, after applying the lubricant 119 to the hard disk 110 and then performing long-time ultraviolet irradiation under atmospheric pressure in order to increase the bond rate, ozone is generated and contaminants such as organic substances are generated. This produces the acid. The organic acid also oxidizes the protective film 117 and the lubricating film 119 itself, so that the surface of the hard disk 110 is corroded.
Thus, when the surface is corroded, the uniformity of the lubricating film surface is lost, so that the water repellency is reduced and the frictional resistance is increased.

The heat treatment after the application of the lubricant 119 also increases the bond rate and improves the water repellency, but cannot improve the water repellency and the bond rate as compared with the case of irradiation with ultraviolet rays. However, there is a drawback that a so-called film reduction occurs due to volatilization of a volatile component of the lubricant by heating. Furthermore, the above-mentioned conventionally proposed technology requires a facility for applying a lubricant on the protective film, and then performing an ultraviolet irradiation or a heat treatment on the lubricant to perform the treatment. Process and time were required.

As is clear from the above description,
Conventionally, the post-application treatment for increasing the bond ratio of the lubricating film has rather caused a problem, and it has been difficult to form a satisfactory lubricating film on the hard disk. Accordingly, it is an object of the present invention to provide a magnetic recording medium having a lubricating film having improved water-repellent properties by improving the bond rate without performing processing after the application of a lubricant, and having excellent low friction and wear resistance. Is to do.

[0013]

The above object is achieved by a magnetic recording medium having a lubricating film formed by applying a lubricant after irradiation with ultraviolet light to the surface thereof. In the first aspect of the present invention, the lubricant is polymerized and polymerized by being subjected to the treatment of ultraviolet irradiation. Since the lubricant after this treatment is applied onto the magnetic recording medium, a lubricating film having a high bond rate and a strong attraction force is formed on the surface of the magnetic recording medium. Since there is no need to apply a treatment such as ultraviolet irradiation after applying the lubricant to the magnetic recording medium as in the related art, the above-described conventional problem associated with this is also eliminated.

[0014] The treatment of irradiating the lubricant with ultraviolet light can be performed on the lubricant before the application. Therefore, when compared with the case where each magnetic recording medium is treated after applying a lubricant as in the past,
Since the process is simplified and the process time is also shortened, manufacturing at low cost becomes possible. According to a second aspect of the present invention, in the first aspect, the lubricant is a perfluoropolyether having a benzene ring at a terminal group (Perfl).
(uro-Polyether) compound.

According to the second aspect of the present invention, the perfluoropolyether compound having a benzene ring is polymerized with a predetermined absorptivity to ultraviolet rays and polymerized to be stable on the surface of the magnetic recording medium. It will be adsorbed with the property. Further, as described in claim 3, in the invention according to claim 2, it is preferable that the terminal group includes a piperonyl group.

According to the third aspect of the present invention, the presence of a piperonyl group at the terminal of the polymer of the polymerized perfluoropolyether compound causes the polymer to polymerize when irradiated with ultraviolet light, thereby becoming a polymer. It can be stably adsorbed on the surface of the magnetic recording medium. The above object is achieved by an ultraviolet irradiation step of irradiating the lubricant with ultraviolet rays to polymerize the lubricant, and a coating step of applying the lubricant after the ultraviolet irradiation step to the surface of the magnetic recording medium. And a method for manufacturing a magnetic recording medium, comprising:

In the invention according to claim 4, the lubricant is polymerized and polymerized in an ultraviolet irradiation step. Since the lubricant after the ultraviolet treatment is applied on the magnetic recording medium in the application step, a lubricating film having a high bond rate and a strong attraction force is formed on the surface of the magnetic recording medium. At that time, the treatment of irradiating the lubricant with ultraviolet light can be performed collectively in the container.

Therefore, it is not necessary to apply a treatment such as ultraviolet irradiation to each magnetic recording medium after the lubricant has been applied to the magnetic recording medium as in the prior art, and the above-mentioned problems associated with the treatment after the application do not occur. In addition, since the process is simplified and the process time is shortened, the manufacturing cost can be reduced. As described in claim 5, in the invention according to claim 4, after the ultraviolet irradiation step and before the coating step,
It is preferable that the method further includes a purification step of removing unnecessary portions in the lubricant.

According to the fifth aspect of the present invention, by removing unnecessary portions after being irradiated with ultraviolet rays, it is possible to apply a polymerized and polymerized lubricant onto a magnetic recording medium,
It is possible to form a lubricating film having a higher bond rate and a good adsorbability on the magnetic recording medium. Here, the unnecessary portion is an unreacted portion such as a molecule of the lubricant that did not polymerize even when subjected to the ultraviolet irradiation treatment or a terminal group that does not contribute to the polymer generated by the polymerization reaction. By using an organic solvent, for example, butyl acetate, acetone, benzene or the like, a polymerized portion can be separated except for an unnecessary portion.

The lubricating film formed on the magnetic recording medium as described above may be subjected to a cleaning treatment. By the cleaning process,
Further, a lubricating film having a higher bond ratio can be obtained. In the invention according to claim 4 or 5, after the coating step,
The configuration may further include a step of performing a heat treatment on the lubricant after application. With this configuration, by performing a heat treatment on the lubricant after application, it is possible to further improve water repellency and suppress contaminants. As described above, according to the manufacturing process of the present invention, a lubricating film having good adsorptivity can be formed on a magnetic recording medium. However, a more preferable lubricating film can be obtained by further performing a heat treatment after applying the lubricant.

However, the heat treatment here is not a treatment for imparting a bond rate and water repellency to an untreated lubricant as in the prior art. Does not occur.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
An embodiment of the present invention will be described. First, FIG. 2 is a view schematically showing a step of applying a UV treatment to the lubricant of the embodiment and a step of applying the lubricant to a magnetic recording medium. In FIG. 2, a step (I) is an ultraviolet irradiation step of irradiating the liquid lubricant 1 with ultraviolet light to polymerize the liquid lubricant 1.

The lubricant 1 is put into the container 2 through which the ultraviolet rays 3 can pass. The lubricant 1 is a perfluoropolyether compound having a benzene ring at a terminal group, preferably a perfluoropolyether compound having a piperonyl group at a terminal. For example, Fomblin AM30
01 (manufactured by Ausimont) can be used. As the container 2 through which the ultraviolet rays 3 can pass, for example, quartz glass can be used. The container 2 may be formed of a material that can transmit ultraviolet rays. However, in consideration of prevention of contamination of the contained lubricant 1 with the contained lubricant 1 and transmission efficiency of ultraviolet rays, a single crystal of silica (SiO ₂ ) is used. It is preferable to use a certain quartz glass container.

Further, regarding the shape of the container 2, the opening of the container 2 is prevented in order to prevent the generation of ozone and oxidation of the lubricant 1 when the lubricant 1 is irradiated with ultraviolet rays in a subsequent step. Is preferably small. Lubricant 1 more reliably
In order to prevent oxidation of the container 2, the container 2 may be sealed with a stopper. Further, the upper space in the container 2 may be replaced with an inert gas and sealed with a stopper.

Ultraviolet rays 3 are irradiated from the outside of the container 2 to polymerize the lubricant 1 inside. Specifically, in step (I), for example, about 10 mL of Fomblin AM3001 is introduced into a quartz glass container having a volume of about 100 mL, and ultraviolet rays 3 having a wavelength of, for example, about 172 nm are irradiated from the outside of the quartz glass container 2 for about 2 hours. The internal lubricant 1 is polymerized. The wavelength of the ultraviolet light used here is not particularly limited, but in consideration of the case where a quartz glass container is used, it is preferable to use ultraviolet light having a wavelength of about 220 nm to about 150 nm.

Next, the purification step (II) is to separate and purify the polymerized portion of the lubricant 1 in the ultraviolet irradiation step (I). In the purification step (II), the lubricant 1 treated in the ultraviolet irradiation step (I) and the organic solvent 4 for separation are mixed, and the unnecessary part is dissolved in the organic solvent 4 side and separated. This purification step (II) can be omitted. However, by previously removing unnecessary portions generated in the ultraviolet irradiation step (I), the ratio of polymerized portions in the lubricant 1 can be increased, and the surface of the magnetic recording medium 1 is corroded. If such contaminants are generated, they can be removed. Therefore, the bond rate when applied on the magnetic recording medium 10 is increased,
From the viewpoint of preventing the occurrence of corrosion of the magnetic recording medium 1, it is preferable to include this refining step (II).

In the purification step (II), for example, a separation funnel 20 can be used to separate an unnecessary portion and a polymerized portion in the lubricant 1. Specifically, the lubricant 1 and the organic solvent 4 treated in the ultraviolet irradiation step (I) are mixed and dissolved by shaking. When this is left standing, an unnecessary portion having a small molecular weight is dissolved on the organic solvent 4 side. Therefore, by removing the organic solvent 4 side, a polymerized portion in the lubricant 1 can be obtained.

As the organic solvent 4, a general organic solvent can be used. For example, butyl acetate, acetone, benzene and the like are used, but butyl acetate is preferably used from the viewpoint of good processability. In the purification step (II), the separation may be performed using a GPC (gel permeation chromatography) column. Lubricant 1 and organic solvent 4
When the mixed solution is passed through the GPC column at a low pressure, the unnecessary portion in the lubricant 1 passes relatively quickly because it is relatively light, and the polymerized portion passes relatively heavily and slowly, so that both portions must be separated. Can be.

The lubricant 1 treated in the step (I) (or further in the step (II)) is applied onto the magnetic recording medium 10 in an application step (III). The lubricant 1 is a fluorine-based solvent 5 for coating, for example, Fluorinert FC77
(Manufactured by 3M) to obtain a lubricant solution 6 having a concentration of about 0.05% by weight. The magnetic recording medium 10 has the same configuration as that of the conventional magnetic recording medium 110 shown in FIG. 1, and has a surface prepared by forming a carbon-based carbon film, for example, DLC. The lubricant solution 6 is applied to the surface of the magnetic recording medium 10.

As the coating treatment, for example, the pulling speed is about 10 to about 350 mm / s, and the immersion time is about 30 seconds.
d. The method of applying the solution 6 to the surface of the magnetic recording medium 10 is not particularly limited, and may be applied by a spin coater method, a wipe method, or the like.
Further, the cleaning process of the lubricating film 19 will be described. In principle, the magnetic recording medium 10 according to the present embodiment has a sufficient bonding ratio and a sufficient low friction / abrasion resistance and water repellency after the above-described steps (I to III or I and III). A lubricating film 19 is provided.

However, the mobile layer 19b still exists in the film constituting the lubricating film 19. Although not shown in FIG. 2, after the above-described step (III), the magnetic recording medium 10
May be added to the cleaning solvent.
By this cleaning treatment, the mobile layer 19b weakly bonded to the carbon-based protective film can be removed. Therefore, the magnetic recording medium 10 having a lubricating film 19 with a higher bonding rate on the surface.
Can be obtained.

As the washing solvent used here, the same solvent as the fluorine-based solvent 5 used for diluting the lubricant 1 can be used. However, the mobile layer 19b
Any other solvent may be used as long as it is a solvent capable of removing the same. The cleaning process is performed, for example, with a dipping time of 30 seconds.
c, It may be immersed in a solvent for cleaning at a lifting speed of 2.3 mm / sec.

Next, the heat treatment of the lubricating film 19 will be described. After the application of the lubricant 1, a heat treatment step (IV) may be further added to the magnetic recording medium 10. This heat treatment step (IV) may be performed after the above-mentioned cleaning treatment. The heat treatment step (IV) can be performed at a predetermined temperature, for example, about 120 ° C. while the magnetic recording medium 10 having the lubricating film 19 is held in the thermostat 9. By performing this heat treatment on the lubricating film 19, the water repellency is further improved, and any remaining volatile contaminants can be removed, so that contamination on the surface of the magnetic recording medium can be more reliably prevented. Can be.

The heat treatment in the heat treatment step (IV) has a different meaning from the conventional heat treatment. That is,
Conventionally, the treatment is performed to impart low friction, abrasion resistance, water repellency, and the like to the magnetic recording medium 110 having an untreated lubricating film applied to the surface. However, in the heat treatment in this embodiment, the lubricating film 19 having a constant bond rate and already having low friction, abrasion resistance and water repellency is further improved in water repellency and surely eliminating contaminants. For the purpose. Therefore, the heat treatment is completed in a short time of 30 minutes or less as compared with the conventional heat treatment time of 1 to 2 hours. Therefore, the heat treatment step (IV) in the present embodiment
Thus, the problem of film reduction does not occur as in the related art.

The magnetic recording medium 10 formed by applying the lubricant 1 after irradiation with the ultraviolet light, which is manufactured as described above, to the surface thereof.
Has a preferred lubricating film 19 on its surface. The lubricating film 19 has a high ratio (bond ratio) of the bond layer 19a,
It has low friction, abrasion resistance and high water repellency. The thickness of the lubricating film 19 formed as described above can be reduced from about 1.0 nm to about 2.5 nm by appropriately changing various conditions in the above-described steps. As described, it is preferred that the magnetic spacing be in the range of about 1.3 nm to about 1.6 nm to reduce magnetic spacing.

Hereinafter, the magnetic recording medium 10 of the above embodiment will be further described based on data confirmed by the present inventors. FIG. 3 is a diagram showing data confirming that the lubricant 1 is polymerized and polymerized when the lubricant 1 is irradiated with ultraviolet rays. The lubricant 1 was irradiated with ultraviolet rays having a wavelength of about 172 nm at different times, and GPC analysis was performed for each treatment time to observe changes in molecular weight.

FIG. 3 (A) is a view showing zero irradiation time of the ultraviolet light, that is, the untreated lubricant 1 before the irradiation of the ultraviolet light. The lubricant 1 used in this analysis was the Fomblin AM3001, the average molecular weight was about 3200,
The peak is shown at the center of the horizontal axis. In addition, in each figure of FIG. 3, it is shown that a molecular weight is so large that it is the left side.

FIG. 3 (B) shows the case where the irradiation time of ultraviolet light is set to 0.2 hours, and FIG. 3 (C) shows the case where the irradiation time of ultraviolet light is set to 0.5 hours. It can be confirmed that the polymer is polymerized and polymerized by irradiation, and that the polymerization of the lubricant is promoted as the UV irradiation time increases. Although not shown here, the present inventors have confirmed that the polymerization time is promoted even when the irradiation time of the ultraviolet rays is further extended to 2 hours.

As described above, the average molecular weight of the lubricant 1 changes depending on the processing time, but is estimated to be about 10,000 or more. Further, FIG. 4 shows that the lubricating film 119 on the conventional magnetic recording medium 110 described above and the lubricating film 19 formed by applying the lubricant 1 after the irradiation of the ultraviolet light according to the present embodiment are combined with each other for water repellency, bond rate and It is a figure showing the data compared about frictional force.

The data shown here are for the lubricating film 19 of the embodiment formed without performing the cleaning treatment and the heat treatment (IV) in the above-described steps. FIG. 4A shows the water repellency of the conventional lubricating film 119 and the lubricating film 19 of the embodiment when the lubricating film thickness (nm) is changed, using the contact angle. Here, the contact angle is measured by dropping a predetermined amount of water droplet on the lubricating film, and at a contact point between the water droplet and the lubricating film surface, an angle between a tangent drawn to this and the lubricating film surface is defined as a contact angle. I have. The larger the contact angle, the higher the water repellency.

In FIG. 4A, a conventional lubricating film 119 is formed.
The contact angle increases as the layer thickness increases, but the maximum is about 8
0 degrees. On the other hand, the lubricating film 19 of the present invention has a contact angle exceeding 80 degrees at a minimum, and it can be confirmed that the water repellency is extremely high. In addition, the water repellency is improved when the processing time is set to 2 hours rather than 1 hour. Therefore, it can be confirmed that the water repellency of the lubricant can be improved by increasing the irradiation time of the ultraviolet light.

Although it is not clear why the water repellency is improved as described above, the conventional lubricating film applies a lubricant to a magnetic recording medium and then irradiates with ultraviolet rays. Is formed on the surface of the magnetic recording medium, and it is presumed that sufficient water repellency cannot be obtained. On the other hand, in the present invention, the lubricant is polymerized by irradiation with ultraviolet rays before coating, and preferably a polymer portion is used except for unnecessary portions. Therefore, the lubricant 1 in which the contaminants are suppressed and polymerized can be applied onto the magnetic recording medium, and the uniformity of the lubricant surface is maintained, so that it is estimated that the water repellency of the lubricant film 19 is increased.

FIG. 4B shows the bond ratio of the conventional lubricating film 119 and the lubricating film 19 of the embodiment when the lubricating film thickness (nm) is changed. The bond ratio is a ratio of the film thickness left on the magnetic recording medium after performing the cleaning process to the film thickness when the lubricating film is formed on the magnetic recording medium. In FIG. 4B, the conventional lubricating film has a bond rate of less than 60% at the maximum. On the other hand, the lubricating film of the present invention has a bond ratio exceeding 60% in a practical range of about 1 nm to about 1.5 nm. Further, it can be seen that the bond rate is higher when the treatment time is 2 hours than when the treatment time is 1 hour, and that the bond rate of the lubricating film is increased by increasing the irradiation time of the ultraviolet light. The reason for this is that, as shown in FIG. 3, the increase in the ultraviolet irradiation time promotes further polymerization, and the molecular weight of the lubricant is larger when the treatment time is 2 hours than when the treatment time is 1 hour. Can be presumed to be a polymer, and the adsorptivity to the surface of the magnetic recording medium is improved.

FIG. 4C shows the static friction of the conventional lubricating film 119 and the lubricating film 19 of the embodiment when the lubricating film thickness (nm) is changed. The friction force here is C
It measured using the SS tester. FIG. 4 (C) shows that the frictional force of the lubricating film of the present invention is substantially halved as compared with the conventional lubricating film. Therefore, it can be confirmed that the lubricating film 19 of the example has low friction properties. The reason is presumed that the lubricant of the present invention is applied after being subjected to an ultraviolet irradiation treatment and polymerized before application, so that the uniformity of the surface is maintained.

Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the specific embodiments, and within the scope of the present invention described in the claims, Various modifications and changes are possible. The present invention described above, instead of performing a treatment such as ultraviolet irradiation after applying a lubricant on the magnetic recording medium as in the conventional,
This is based on a completely new idea of applying a UV treatment to a lubricant in advance to polymerize it and applying it.

Therefore, various problems conventionally caused by applying a lubricant on a magnetic recording medium and then performing a treatment such as irradiation with ultraviolet rays are solved, and a high bond rate is achieved, low friction properties, abrasion resistance, and the like. A magnetic recording medium having a lubricating film having high water repellency can be obtained. The lubricating film of the present invention has a higher bond ratio than conventional lubricating films, so that the decrease in the film thickness with time is extremely small, and the surface of the magnetic recording medium has low friction and resistance for a long time. Abrasion and high water repellency can be maintained.

[0047]

As is clear from the above description, according to the first aspect of the present invention, the lubricant after the ultraviolet irradiation treatment is applied onto the magnetic recording medium, so that the bonding ratio on the surface of the magnetic recording medium is reduced. And a lubricating film having a high adsorption force is formed. Since there is no need to apply a treatment such as ultraviolet irradiation after coating as in the prior art, the conventional problem is eliminated.

The treatment of irradiating the lubricant with ultraviolet rays can be performed on the lubricant before coating. Therefore, the process is simplified and the process time is shortened, so that manufacturing at low cost becomes possible. Claims 2 and 3
According to the invention described above, the lubricant is polymerized and polymerized when irradiated with ultraviolet rays, so that the lubricant can be stably adsorbed on the surface of the magnetic recording medium.

According to the fourth aspect of the present invention, since the lubricant after the ultraviolet treatment is applied to the magnetic recording medium in the application step, the ultraviolet irradiation of the lubricant is performed in a container at once. be able to. Therefore, unlike the related art, there is no need to perform a process such as ultraviolet irradiation on each magnetic recording medium, and there is no problem associated with the process after the application. In addition, since the process is simplified and the process time is shortened, the manufacturing cost can be reduced.

According to the fifth aspect of the present invention, by removing unnecessary portions after being irradiated with ultraviolet rays, the polymerized and polymerized lubricant can be applied onto the magnetic recording medium, and the bonding rate can be increased. A lubricating film having high absorption and good adsorbability can be formed on the magnetic recording medium.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a relationship between a magnetic head and a hard disk in a conventional disk drive device.

FIG. 2 is a view schematically showing a step of applying a UV treatment to a lubricant of the embodiment and a step of applying the lubricant to a magnetic recording medium.

FIGS. 3 (A) to 3 (C) are diagrams showing data confirming that the lubricant is polymerized when the lubricant is irradiated with ultraviolet rays.

FIGS. 4A to 4C show data comparing a lubricating film on a conventional magnetic recording medium and a lubricating film according to the present embodiment with respect to water repellency, bond ratio and frictional force, respectively. FIG.

[Explanation of symbols]

 Reference Signs List 1 lubricant 2 container 3 ultraviolet ray 4 organic solvent 10 magnetic recording medium 19b mobile layer 19a bond layer 19 lubricating film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // C10N 40:18 C10N 40:18 60:00 60:00 F term (reference) 4H104 BD06A CD04A JA20 LA03 LA13 PA16 QA12 5D006 AA01 5D112 AA07 BC02 BC10 CC01

Claims (5)

[Claims] 1. A magnetic recording medium having a lubricating film formed by applying a lubricant after irradiation with ultraviolet light to the surface. 2. The magnetic recording medium according to claim 1, wherein the lubricant is a perfluoropolyether compound having a benzene ring in a terminal group. 3. The magnetic recording medium according to claim 2, wherein the terminal group includes a piperonyl group. 4. A method for producing a magnetic recording medium, comprising: an ultraviolet irradiation step of irradiating a lubricant with ultraviolet rays to polymerize the lubricant; and a coating step of applying the lubricant after the ultraviolet irradiation step to a surface of the magnetic recording medium. 5. The method for manufacturing a magnetic recording medium according to claim 4, further comprising a purification step of removing unnecessary portions in the lubricant after the ultraviolet irradiation step and before the coating step. .