JP2000163818A - Lubricating layer, information recording medium, its production and information recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent sucking with a head and to obtain good lubricating property and durability by forming a lubricant layer consisting of a hardening resin and porous crosslinked vinylpolymer fine particles impregnated or copolymerized with a lubricant. SOLUTION: As for the lubricant, a lubricant which can impregnate porous crosslinked vinylpolymer fine particles and which is liquid is preferable, and for example, a silicon lubricant and a fluorine lubricant are used. As for a preferable compd., a polyorganosiloxane having 1000 to 20000 number average mol.wt. which may be modified, or a perfluoropolyether having -CaF2aO- unit in the main chain (wherein (a) is an integer 1 to 4) or a perfluoroalkyl compd. which may be modified, can be used. As for the porous crosslinked vinylpolymer fine particles, a compd. which can be formed hard and can be controlled for the particle size is used, and for example, a styrene-divinylbenzene crosslinked copolymer is used. The lubricant is applied by dipping or spray coating, and hardened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lubricating layer, an information recording medium having the lubricating layer, a method for manufacturing the same, and an information recording apparatus.

[0002]

2. Description of the Related Art With the development of computer technology, the capacity of recording devices has been steadily increasing. In a magnetic recording device such as a hard disk device, an MR head or a G
MR heads have come to be used, and the flying height of the magnetic head has rapidly decreased. Accordingly, the floating magnetic head and the magnetic recording medium are liable to contact and slide at a high speed, so that they are liable to be damaged by wear or to deteriorate magnetic properties.

On the other hand, conventional optical disks include a read-only type (ROM), a rewritable type (RAM), and a write-once type. In these media, an optical head is provided on the side opposite to the recording surface of the optical disk substrate. Therefore, a so-called substrate surface incidence method is adopted, in which read light or recording light emitted from an optical head passes through a substrate and reaches a recording surface. The optical head is provided with an objective lens movable in the direction of the focal axis by an actuator so that these lights are focused on the recording surface. Therefore, the distance between the optical head and the disk is usually about 1 mm.

However, in a magneto-optical recording medium employing a magnetic field modulation overwrite method, a floating magnetic head or a contact type (sliding type) magnetic head is arranged on the recording layer side in addition to the optical head in many cases. Then, both heads perform recording in cooperation. In this case, particularly when the overwriting method based on the CSS method (contact start and stop method) is adopted, the contact and sliding of the magnetic head with the recording medium surface occur at the start and stop of the rotation of the medium. Wear, damage, adhesion of the head to the recording medium surface, and head crash are likely to occur.

Further, in recent years, as a recording / reproducing apparatus having a large capacity and a high speed access, an apparatus using a variety of existing optical disks such as a magneto-optical recording medium, a phase-change optical recording medium, a dye-type optical recording medium as a hard disk has been proposed. ing.
In other words, one or two or more optical disks fixed coaxially are built in, an optical head is provided to face each recording surface, and light is irradiated from the recording surface side without passing through the substrate, so-called film surface incidence. To perform recording and reproduction. In the conventional substrate surface incidence method, the numerical aperture of the objective lens could not be increased because the aberration of the light spot increased due to the inclination of the substrate and errors in the thickness of the substrate. By increasing the numerical aperture and decreasing the light spot, it is possible to increase the capacity of the optical disk and to access the disk at high speed.

FIG. 2 shows an example of such a recording / reproducing apparatus. A plurality of double-sided recording type optical discs 11, 11 ', 1
1 ″ is coaxially fixed, and two optical heads 12, 13, 12 ′, 1
3 ', 12 ", 13" are arranged. These optical heads are arranged on the same support arm 14, fixed coaxially, and move in conjunction. The moving direction of the optical head may be a radial direction or a rotation about an axis on which these heads are supported.

The distance between the optical disk and the head differs depending on the head, but is usually set to 3 μm or less.
In the case of a floating head with a lens, reflector, or optical fiber installed on a floating slider, to maintain this distance, the spring pressure of the arm that presses the slider against the disk and the buoyancy required for floating are obtained. The area and shape of the slider are set. Further, a contact type head in which a slider portion and a disk surface are partially in contact has been proposed.

When recording information sent from the outside, each head detects address (physical position on the substrate) information based on preformats such as pits and grooves recorded in advance. Then, information is recorded on the recording layer of the optical disk facing the optical disk. Regarding the method of recording information, either one head or both heads may be used at the same time.

When reading information recorded on a disk, the position of the recorded information is searched by a head and read. At this time, each of the heads with respect to the recorded information so as to maximize the reproduction signal strength
Servo adjustment should be performed independently. When the rotation of the disk is stopped, the head position is close to or in contact with the disk only when the disk is rotating, as in the dynamic loading method, even if the head is in contact with the disk as in the so-called CSS method. May be in a state sufficiently separated from the disk when the recording is stopped.

However, it has been found that there are the following problems when an optical disk is used in the recording / reproducing apparatus. That is, in the conventional optical disk, the distance between the optical head and the substrate is usually 1 mm or more,
When an optical disk is used in the recording / reproducing apparatus, the distance between the optical head and the substrate is extremely short, usually within 3 μm, so that the optical head may collide with the optical disk and damage the medium or damage the head. Was. In particular, collisions are likely to occur during dynamic loading.

[0011]

Therefore, on the recording layer of a magnetic recording medium or an optical recording medium, the surface is roughened for the purpose of protecting the recording layer and improving the CSS characteristics between the magnetic head and the recording medium. Attempts have been made to form a lubricating layer having high lubricity. Several proposals have been made for the formation of such a lubricating layer.

For example, JP-A-4-229433 and JP-A-5-67359 propose to provide a lubricating layer comprising an ultraviolet curable resin film containing a lubricating filler. However, silicon filler, fluororesin filler, graphite as solid lubricant, molybdenum disulfide, and hexagonal boron nitride are exemplified as lubricating fillers, but these fillers are actually mixed with an ultraviolet curable resin as it is. No effective lubricating layer could be formed at all even when applied and cured.

This is because the adhesion between the lubricating filler and the ultraviolet curable resin is inferior, the fine particles are gradually peeled off from the ultraviolet curable resin layer and the lubricating property is reduced, and the particle size of the lubricating filler is taken into consideration. Therefore, the unevenness of the surface of the lubricating layer is not controlled, and it is difficult to contribute to the reduction of the friction of the lubricating layer. Furthermore, since the filler is soft, it is crushed at the time of CSS, and the lubricating layer has a rough surface effect. Because there is no.

Further, Japanese Patent Application Laid-Open Nos.
In JP-A-302835 and JP-A-4-315839, the surface is roughened with an inorganic fine particle such as silica and alumina, and an ultraviolet curable resin containing a lubricant such as silicon oil and a higher fatty acid.
A method for forming a lubricating layer having lubricity has been proposed. However, in this method, since the inorganic particles such as silica and alumina and the lubricant are contained separately, the surface of the lubricating layer is once appropriately covered with the lubricant when the lubricating layer is formed, but the lubricant gradually shakes off during use. It was poorly durable because it was not replenished after disappearing. Further, there is a problem that the affinity between the inorganic fine particles and the organic compound of the ultraviolet curable resin is not always good, and it is difficult to disperse, and the resin once formed is easily phase-separated and difficult to store.

Further, Japanese Patent Application Laid-Open No. 4-255935 proposes to provide an organic lubricating layer filled with a bead-shaped hollow resin powder in which a hollow portion is filled with a lubricating oil, on a recording film of a magneto-optical disk. . Since the resin powder is used, it has good affinity with the organic substance serving as the lubricating layer, but in this method, although the lubricating layer surface is roughened, the lubricating oil is filled inside the beads, so that the lubricating oil has a poor lubricity. The contribution was very poor.

The present invention has been made to solve the above problems. In other words, the present invention has excellent lubricity and abrasion resistance in a thin film, and prevents aggregation of a lubricant and suppresses spin-off. The purpose of the present invention is to obtain a lubrication layer and an information recording medium.Furthermore, when a flat substrate corresponding to a floating type head or a contact type head in which the head is lowered is used, the suction with the head does not occur. It is an object of the present invention to obtain a lubricating layer and an information recording medium having good lubricity and sufficient durability.

It is another object of the present invention to reduce the flying height of the head with respect to the information recording medium, increase the data recording density of the medium, and obtain an information recording medium and an information recording apparatus having high reliability over a long period of time.

[0018]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a lubricant layer comprising porous crosslinked vinyl polymer fine particles impregnated or copolymerized with a lubricant and a curable resin, and an information recording medium using the same. And its manufacturing method and information recording device. The lubricating layer of the present invention has good affinity between the curable resin forming the lubricating layer and the fine particles composed of the organic compound,
It is easy to prepare and store a stable resin for forming a lubricating layer. In addition, the surface of the lubricating layer can be appropriately roughened by fine particles having a controlled particle size, and since it is a crosslinked vinyl polymer system, it is sufficiently hard to withstand CSS, and the lubricant is retained in its pores. Therefore, they have the feature of acting as particles maintaining lubricity.

The information recording medium on which the lubricating layer is formed has excellent lubricity and abrasion resistance, prevents aggregation of the lubricant and suppresses spin-off, and maintains excellent durability for a long period of time. Therefore, the suction with the head does not occur. As a result, the flying height of the head with respect to the information recording medium can be reduced, the data recording density of the medium can be increased, and an information recording apparatus having high reliability over a long period of time can be obtained.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the porous crosslinked vinyl polymer-based fine particles, particles that can be hardened, can impart porosity, and can control the particle size are preferable. For example, a styrene-divinylbenzene crosslinked copolymer is used.

When used as a lubricating layer of an information recording medium,
In particular, when a floating type head or a contact type head is used, the average particle diameter of the fine particles is preferably 10 μm or less. When the average particle size exceeds 10 μm, when a contact type head in which the head is continuously slid is used, particles are likely to drop off, which is likely to cause noise and head contamination. When a floating head is used, there is no such a concern, but the head is difficult to fly, and the friction between the head and the medium lubricating layer is significantly increased. Further, large projections are likely to be formed on the surface of the lubricating layer, which may easily cause collision with the head or increase friction with the head. Particularly preferred is an average particle size of about 2 μm or less.

As the lubricant, those which are impregnated in the porous crosslinked vinyl polymer fine particles, that is, liquid lubricants are preferable, and examples thereof include silicon-based lubricants and fluorine-based lubricants. Preferred compounds have a number average molecular weight of 1000
～20000 of modified unprotected polyorganosiloxanes also, or in the main chain -C _a F _2a O- units (where, a
Is an integer from 1 to 4),
Alternatively, a perfluoroalkyl compound which may be modified may be mentioned. These lubricants are characterized in that they have both an affinity required for being incorporated into the porous crosslinked vinyl polymer-based fine particles and a lubricating effect due to release from the porous crosslinked vinyl polymer-based fine particles.

The polyorganosiloxane has, for example, a repeating unit represented by the following general formula [I].

[0024]

Embedded image

(Wherein R ¹ and R ² are a methyl group, an ethyl group or a phenyl group) When the number average molecular weight is less than 1,000, the lubricating effect of the polyorganosiloxane is reduced. It is not preferable because it is difficult to be taken into the hydrophilic crosslinked vinyl polymer fine particles. Number average molecular weight of 1000-2
As the polyorganosiloxane of 0000, for example,
Shin-Etsu Chemical Co., Ltd. KF96 can be mentioned.

More preferably, the number average molecular weight is 1000
Alkoxy-modified products of polyorganosiloxane ～20000, polyether-modified product or (meth) acrylic-modified product, or the main chain -C _a F _2a O- units (wherein, a is 1
Perfluoropolyether and having a functional group of the ester bonded to the terminal has 4 integer), -C _b F _2b in the main chain - units (wherein, b is an ester bond at the terminal has an integer) from 1 to 15 Is a compound having a functional group of

Examples of the alkoxy-modified or polyether-modified polydimethylsiloxane include, for example, KF-851 and KF-352 manufactured by Shin-Etsu Chemical Co., Ltd.
Can be mentioned. As the (meth) acrylic modified polydimethylsiloxane, for example,

[0028]

## STR2 ## _{CH 2 = C (CH 3)} COO (CH 2) 3 (OSi (CH
₃ ) ₂ ) _n OSi (CH ₃ ) ₃ . As an example of the perfluoropolyether, there may be mentioned Fomblin-Z series manufactured by Ausimont Co., Ltd.

For example, Fomblin manufactured by Ausimont Co., Ltd.
-Z DEAL is a polymer of CF ₂ CF ₂ O and CF ₂ O and has a linear structure, and has an ester group —COOR (both in which
R represents an alkyl group which may be substituted by fluorine. ). In addition, demnum manufactured by Daikin Industries, Ltd.
The type (SP or SY) is a homopolymer of hexafluoropropylene oxide, and has an ester group -CO at one end.
OR (where R represents an alkyl group which may be substituted with fluorine).

Fomblin-Z D manufactured by Ausimont
The structural formula of EAL is as follows.

[0031]

Embedded image ROOCCF ₂ [(OCF ₂ CF ₂ ) _p- (OCF ₂ ) _q ]
OCF ₂ COOR (R is an alkyl group having 2 to 3 carbon atoms) The structural formula of Demmnum SY manufactured by Daikin Industries, Ltd. is as follows.

[0032]

Embedded image

As the perfluoroalkyl compound, for example,

[0034]

Embedded image compounds such _{CH 2 = CHCOOCH 2 CH 2 (} CF 2) 8 CF 3 and the like. The molecular weight of the lubricant is 100
It is preferably in the range of 20,000 to 20,000. If the molecular weight is low, the vapor pressure is generally high, evaporates little by little after coating, and moves away from the desired film thickness with time. Conversely, when the molecular weight is high, the viscosity is generally high, and the desired lubricity may not be obtained.

As a solvent for dissolving these, for example, fluorocarbons, alcohols, hydrocarbons, ketones,
Ether type, fluorine type, aromatic type and the like are used. Further, when a lubricant component is partially copolymerized in the fine particles using a compound having an ethylenically unsaturated group capable of reacting with the fine particles in these lubricants, lubricity can be more effectively imparted. In addition, there is a feature that the lubrication effect is permanent.

Examples of such a lubricant include a radically polymerizable silicone macromonomer having an ethylenically unsaturated group at one end of a polyorganosiloxane having a number average molecular weight of 1,000 to 20,000, or -C _b F _{2b in the} main chain.
-A compound having a unit (where b is an integer of 1 to 15) and having a (meth) acrylate group at a terminal. These are particularly preferable from the viewpoints of affinity and reactivity with a vinyl monomer forming the porous crosslinked vinyl polymer fine particles and availability.

If the molecular weight is less than 1,000, the lubricating effect of the polyorganosiloxane is reduced, and if it is more than 20,000, it is difficult to react during the formation of the porous crosslinked vinyl polymer fine particles and it is difficult to be taken in. Examples of such a polyorganosiloxane having a number average molecular weight of 1,000 to 20,000 include X-22-174DX manufactured by Shin-Etsu Chemical Co., Ltd. and Chisso Corporation.
FM0721 and the like.

The curable resin used in the present invention may be any resin that can be cured by any means such as light or heat. Examples thereof include thermosetting resins such as epoxy resin, phenol resin, and alkyd resin, and (meth) acrylic resin. Radiation-curable resins such as acid esters are exemplified. Among these, an ultraviolet curable resin containing polyfunctional acrylate as a main component is preferably used from the viewpoints of inexpensive materials, relatively simple equipment, and rapid curing.

Next, a preferred method for producing the lubricating layer in the present invention will be described. First, a method for preparing fine particles obtained by impregnating a porous crosslinked vinyl polymer-based fine particle with a lubricant will be described. Methods for producing porous crosslinked vinyl polymer-based fine particles are known, and are actually used as synthetic adsorbents and ion exchange resins. For example, as a commercial product having a styrene-divinylbenzene copolymer as a base, Diaion HP-1 is commercially available.
0, 20, 30 (manufactured by Mitsubishi Chemical Corporation) and Amberlite XAD2, 4 (manufactured by Rohm & Haas).

These fine particles are prepared by suspension polymerization of a vinyl monomer such as styrene or divinylbenzene in a dispersion medium in which the monomer is not dissolved, or by mixing a solvent in which the monomer is dissolved with a dispersion medium for preventing agglomeration of formed particles. It is produced by a method of polymerizing in a solution to gradually precipitate fine particles. For controlling the porosity and the degree of crosslinking, the composition ratio of the vinyl monomer, the concentration of the dispersion medium used, and the manner of stirring the reaction system during polymerization are important. This is described, for example, in Japanese Patent Publication No. 5-49337.
And so on.

The average particle size of the porous crosslinked vinyl polymer fine particles is determined by the concentration of the dispersing medium used in the polymerization for forming the particles,
Stirring of the reaction system during the polymerization, amount of the solvent, viscosity and the like are important. This is also described in JP-B-63-30948. When it is desired to obtain a target particle in which a lubricant is impregnated as in the present invention, it is of course possible to adopt a method of impregnating the lubricant after forming only the particle first, but it is possible to adopt a method in which all or all of the dispersion medium is used. The method of using the lubricant as a part is more convenient and preferable.

It is considered that the pores of the fine particles are formed by agglomeration of fine particles of the insoluble crosslinked copolymer formed in the polymerization droplets during the polymerization process, and the gaps remaining as pores. Therefore, when a lubricant is co-present in the polymerization process, if the selection of the lubricant is appropriate, it is possible to produce porous crosslinked vinyl polymer-based fine particles appropriately containing (impregnated) the lubricant.

It is preferable to use a lubricant having an affinity for the vinyl monomer when employing this method. If there is no affinity for the vinyl monomer, the particles are not taken into the pores during the production of the particles, and are not easily taken into the pores after the production of the particles. When a compound capable of reacting with a vinyl monomer is used as a compound capable of functioning as a lubricant, fine particles in which a lubricant is covalently bonded to porous crosslinked vinyl polymer-based fine particles can be obtained. Such fine particles not only have lubricating properties themselves, but also have excellent retention performance of the lubricant incorporated in the pores, so that a lubricating layer having more stable lubricating properties over a long period of time is required. Can be formed.

Since the lubricating layer of the information recording medium is particularly required to have stable durability for a long period of time, it is preferable to use fine particles to which such a lubricant is covalently bonded. And radical-polymerizable silicone macromonomer having a number average molecular weight having an ethylenically unsaturated group at one terminal of the polyorganosiloxane 1000~20000, -C _b F _2b in the main chain
The compound having a unit (where b is an integer of 1 to 15) and having a (meth) acrylate group at a terminal not only reacts with a vinyl monomer forming porous crosslinked vinyl polymer-based fine particles, but also as described above. It also works as a lubricant used as (part of) a dispersion medium during particle formation.

Even when particles are formed using such a compound, some of them do not covalently bond with the porous cross-linked vinyl polymer fine particles, but function as a dispersion medium for forming particles or are taken into pores. Or simply act as a lubricant. Such a compound has a number average molecular weight of 1,000 to 1,000.
An alkoxy-modified, polyether-modified or (meth) acryl-modified 20,000 polyorganosiloxane,
Alternatively, a perfluoropolyether having _a —C _a F _2a O— unit (where a is an integer of 1 to 4) in the main chain and having a functional group of an ester bond at a terminal, or a —C _b F _2b — A compound having a unit (where b is an integer of 1 to 15) and having a functional group of an ester bond at a terminal may be used together.

Next, the curable resin for forming the lubricating layer will be described. As the curable resin, radiation curable resin,
In particular, an ultraviolet curable resin is preferably used, but a resin which gives a relatively hard coating film containing a polyfunctional acrylate as a main component is particularly preferable. The porous crosslinked vinyl polymer fine particles can be dispersed in the curable resin by an appropriate method. A known method can be used for the dispersion method. At this time, the lubrication effect of the lubrication layer can be improved by further adding a lubricant.

The porous crosslinked vinyl polymer fine particles produced by the above-described method have a small particle size, a small degree of aggregation unlike inorganic fine particles, and a good affinity with a curable resin. It can be easily dispersed by using a sound wave dispersion or a bubble homogenizer. Vigorous shaking or stirring with suitable beads, such as those commonly used in the dispersion of inorganic microparticles, can also be used, but this method is not as simple as ultrasonic dispersion because the beads must be separated after dispersion. .

The curable resin in which the porous crosslinked vinyl polymer fine particles thus obtained are dispersed is applied to the substrate surface by a known method such as dip coating, spray coating, bar coating, and roll coating. Is cured to form a lubricating layer. When a lubricating layer is formed on an information recording medium, it is preferable that the lubricating layer is formed by applying the composition onto the recording film by spin coating and then curing the lubricating layer from the viewpoints of productivity and film thickness control.

As the substrate of the magnetic recording medium in the present invention, a disk-shaped non-magnetic substrate made of aluminum, aluminum alloy, glass or the like is used. Normally, these non-magnetic substrates are processed to a predetermined thickness, mirror-finished on the surface thereof, and then subjected to a non-magnetic metal, for example, Ni-P alloy, Ni-C
Approximately 5-20 μm of u-P alloy etc. by electroless plating
It is used after forming a surface layer by forming a film with a thickness of m.

The surface layer formed on the substrate in this way is subjected to texture processing as required, and fine grooves or irregularities are processed and formed with high precision to obtain a surface processed layer finished to a specific surface roughness. . By this texture processing, adsorption between the magnetic head and the magnetic recording medium can be prevented, CSS characteristics are improved, and magnetic anisotropy is further improved. Further, after forming an underlayer on the surface processing layer, a magnetic layer is formed by adhesion. The underlayer is made of, for example, a chromium or Cr alloy, Ni-
It is formed by forming an Al alloy underlayer.

As the magnetic layer formed on the underlayer, Co-Cr, Co-Ni, Co-Cr-X, Co-
A magnetic layer of a Co-based alloy represented by Ni-X, Co-WX or the like is preferable. Here, X is Li, Si,
Ca, Ti, V, Cr, Ni, As, Y, Zr, Nb,
Mo, Ru, Rh, Ag, Sb, Hf, Ta, W, R
e, Os, Ir, Pt, Au, La, Ce, Pr, N
One or more elements selected from the group consisting of d, Pm, Sm and Eu.

The metal magnetic layer made of such a Co-based alloy is formed on the underlayer of the substrate by means such as sputtering. The thickness of the metal magnetic layer is usually
The range is 50 to 600 °. The protective layer includes a carbon film, a hydrogenated carbon film, a nitrogenated carbon film, a carbonized film such as TiC and SiC, a nitride film such as SiN and TiN, SiO, and Al _2.
Although it is composed of an oxide film such as O ₃ and ZrO, a carbon film, a hydrogenated carbon film and a nitrogenated carbon film are particularly preferable. It is formed.

For example, the hydrogenated carbon film is not particularly limited as long as it is a film containing hydrogen and carbon. For example, sputtering is performed in a plasma containing a rare gas and hydrogen gas with carbon as a target. It is formed by doing. As a target used here, diamond-like, graphite-like, or amorphous carbon is used.

Examples of the rare gas include argon, helium, neon, xenon, radon, and krypton. Of these, argon is particularly preferably used. The content of hydrogen gas in a sputtering atmosphere containing a rare gas such as argon gas and hydrogen gas is usually 2 to 2 times.
0 volume%, desirably in the range of 5 to 10 volume%. As the sputtering method, a DC magnetron sputtering method is usually employed, but a high-frequency magnetron sputtering method can also be used.

The pressure in the chamber during sputtering is generally 0.5 to 20 mTorr, preferably 1 to 1 mTorr.
0 mTorr, and the temperature of the substrate is usually 300 ° C. or lower, preferably in the range of room temperature to 250 ° C. The distance between the substrate and the target, the sputtering time, the input power, and the like are appropriately determined according to the thickness of the hydrogenated carbon protective layer to be formed.

Incidentally, the thickness of the hydrogenated carbon protective layer is usually in the range of 50 to 1000 °, preferably 100 to 600 °. On the other hand, a resin substrate provided with pits and grooves is used for the optical recording medium, and as the resin, an acrylic resin, a polyolefin resin such as a norbornene type, a liquid crystal polymer,
Polycarbonate and the like are exemplified, and examples thereof include polymethyl methacrylate (PMMA), ARTON (Nippon Synthetic Rubber Co., Ltd., hydrogenated norbornene-based ester-substituted cyclic olefin polymer), and ZEONEX (Zeon Corporation, norbornene-based cyclic olefin polymer-opened polymer water). Additives), aromatic polyester-based liquid crystal polymers, polycarbonates and the like.

Based on a stamper provided with pits / grooves,
Using these resins, pits / grooves are transferred and formed by injection molding, injection compression molding, radiation curing, or the like to form a resin substrate. Unlike glass, metal, ceramic, etc., the width or length is 2 μm or less and the depth is 100 n by using resin.
m and smaller pits or grooves can be formed precisely and at low cost.

The thickness of the substrate is generally about 0.4 to 2 mm. If the thickness is too thin, the substrate is bent by its own weight and it is difficult to obtain flatness, but if it exceeds 2 mm, there is no great difference in strength. As the optical recording layer formed on the substrate,
Various types can be used. For example, a magneto-optical recording layer, a phase change recording layer, and a dye recording layer are used. The layer configuration is not particularly limited, and various layer configurations can be adopted.

As the magneto-optical recording layer, a rare earth-transition metal alloy film, a magnetic artificial lattice film, an oxide magnetic film, a multilayer film thereof, or the like is used. For example, TbFe, TbF
an amorphous magnetic layer of a rare earth such as eCo, TbCo, GdFeCo, DyTbFeCo and a transition metal, MnBi, Mn
A polycrystalline perpendicular magnetization layer of CuBi or the like, a Pt / Co multilayer film, or the like is used.

The magneto-optical recording layer may be a single layer, or GdTbFe for overwriting or MSR.
Two or more magnetic layers such as / TbFe may be stacked and used. As the phase-change recording layer, for example, compounds such as GeSbTe, InSbTe, AgSbTe, and AgInSbTe can be used.

Preferably, Δ (Sb ₂ Te ₃ ) _1-x (Ge
_{Te) x} 1-y Sb} y (0.2 <x <0.9,0 ≦ y <
0.1) In the alloy and the ternary alloy, up to about 10 atomic% of In, Ga, Zn, Sn, Si, Cu, Au, Ag, P
d, Pt, Pb, Cr, Co, O, S, Se, Ta, N
An alloy thin film containing at least one of b and V is mentioned.

Alternatively, as a material that can be overwritten at high speed, MSbTe (M = In, Ga, Zn, MSbTe) mainly containing a SbTe alloy near the eutectic point of Sb ₇₀ Te ₃₀ .
Ge, Sn, Si, Cu, Au, Ag, Pd, Pt, P
b, Cr, Co, O, S, Se, Ta, Nb and V). On the optical recording layer, a transparent intermediate layer having properties such as weather resistance, high hardness and high lubricity is provided. The material of the intermediate layer is selected in consideration of these properties.

A dielectric is preferable in terms of weather resistance and high hardness. As the dielectric, metal oxide, nitride, chalcogenide, carbide, fluoride, a mixture thereof, and the like are used. Al ₂ O ₃ , Ta ₂ O ₅ , S
iO _2, SiO, a metal oxide such as TiO ₂ alone or a mixture thereof, or a composite oxide of Al-Ta-O, and the like.

Examples of the metal nitride include silicon nitride and aluminum nitride. As chalcogenides,
Zinc chalcogenide such as ZnS, ZnSe, CdS, Cd
II-V group compound such as Se, La ₂ S _3, Ce rare earth sulfides such as _{2 S 3, TaS 2, MgS} , CaS and the like.
Zinc chalcogenide is chemically stable, and among them, ZnS is particularly preferable because of its low toxicity.

As a method for forming these dielectric layers, vapor deposition and sputtering are mentioned, but sputtering is more preferable. Materials having excellent lubricity include carbon films, hydrogenated carbon films, nitrogenated carbon films, carbide films such as TiC and SiC, nitride films such as SiN and TiN, SiO, Al ₂ O ₃ ,
It is composed of an oxide film such as ZrO or the like, and is usually formed by a sputtering method or the like.

More preferred are a carbon film, a hydrogenated carbon film and a nitrogenated carbon film. The hydrogenated carbon membrane is
The film is not particularly limited as long as it is a film containing hydrogen and carbon. For example, using a carbon target, a plasma containing a sputtering gas (usually, an inert gas such as argon is used) and a hydrogen gas is used. And can be formed by a sputtering method.

The nitrogenated carbon film may be a film containing nitrogen and carbon, and is not particularly limited. For example, a sputter gas, a nitrogen gas, a nitrogen monoxide gas, and a nitrogen dioxide gas may be used by using a carbon target. It can be formed by sputtering in a plasma containing a nitrogen-containing gas such as ammonia gas or a nitrogen-containing gas such as air. For example, when air is used, the content of air in the sputtering atmosphere is usually 2 to 20% by volume.

Further, for example, by simultaneously mixing a hydrogen gas and a nitrogen (containing) gas into a sputtering gas,
A hydrogenated and nitrogenated carbon film can also be formed. The intermediate layer has a role as a protective layer and a lubricating layer, but may have a plurality of layers. For example, when a protective layer having high weather resistance and high hardness is provided on the side in contact with the recording layer, and a lubricating layer having excellent lubricity is provided on the side in contact with the lubricating layer, both excellent properties can be obtained as a whole, which is preferable. .

As the layer in contact with the magneto-optical recording layer, silicon nitride, SiO ₂ , Ta ₂ O ₅ or the like is preferably used.
As a layer in contact with the phase-change recording layer, a mixture of ZnS and a metal oxide is preferably used. Preferably, a reflective layer is provided between the substrate and the recording layer. As the reflective layer, a metal or alloy having a high reflectivity is used. For example, Al, Ag, A
u, Cu and alloys containing these as main components.

Further, a transparent intermediate layer may be provided between the substrate or the reflective layer and the recording layer for the purpose of interfering light and amplifying the light or for the purpose of protecting the recording layer. As the material, the above-described dielectric or the like is preferably used.

[0071]

The following examples illustrate the present invention.
The present invention is not limited to the following examples unless it exceeds the gist. Example 1 A first dielectric layer, a magneto-optical recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a polycarbonate substrate having a pregroove having a diameter of 90 mm and a thickness of 1.2 mm by a sputtering method to form a light. A magnetic recording medium was created.

Methacryl-modified dimethylsiloxane (X-22-174DX, manufactured by Shin-Etsu Chemical Co., Ltd.) having 5 g of styrene, 9.1 g of 55% pure divinylbenzene (others are ethylvinylbenzene), and having a number average molecular weight of 4,700.
g, azoisobutyronitrile 0.5 g in heptane 100
and stirred at 70 ° C. under nitrogen with stirring.
Heated for hours.

With time, the reaction system became cloudy due to the styrene-divinylbenzene copolymer fine particles formed. After completion of the reaction, the solvent portion was removed to obtain fine particles obtained by impregnating the porous crosslinked vinyl polymer-based fine particles with a lubricant (methacryl-modified dimethylsiloxane) and partially copolymerizing them. When the particle size of the formed particles was measured in heptane with a particle size distribution analyzer (HORIBA LA-500),
The average particle size was 0.43 μm.

The porous methacrylate modified dimethylsiloxane (X-22-17) was added to 5 parts by weight of the porous crosslinked vinyl polymer fine particles obtained by impregnating a lubricant with the obtained fine particles.
4DX) was impregnated with 8 parts by weight and left to stand overnight. A UV-curable resin (HOD-1011, manufactured by Nippon Kayaku Co., Ltd.) 1
00 parts by weight, an ultrasonic homogenizer (BRANS
ON SONIFIER 450) for 30 minutes. The resin thus obtained did not undergo phase separation even after standing for 3 months.

The obtained resin was filtered using a filter paper and a filter having a pore size of 5 μm (MILLIP-SV SLS manufactured by MILLIPORE).
V025LS), filtered immediately before use, applied on the reflective layer of the magneto-optical recording medium by a spin coating method, and then cured by irradiating ultraviolet rays to form a lubricating layer. The thickness of the lubricating layer was 6.43 μm at a point with a radius of 40 mm (measured by Tencor Corp., Alpha-step).

Next, this magneto-optical recording medium was subjected to CSS.
Tested. In the CSS test, a magneto-optical recording medium was mounted on a spindle motor, and a flying magnetic head having two rails with an air bearing slider size of 5 mm x 5 mm and a rail width of 1.9 mm was used to measure the maximum recording area of the medium. After being arranged on the inner circumference side (radial position r of the core = 25 mm), rotation and stop of the medium at the maximum rotation speed of 3600 RPM were repeated 10,000 times. The time is 1 as the rotation speed rises.
The rotation was performed at 3600 RPM for 3 seconds, the number of rotations decreased for 1 second, and stopped for 1 second, for a total of 6 seconds.

At the same time, when the floating type head changes from the landing state to the floating state, the force for pulling the head in the rotation direction of the magneto-optical recording medium is applied to a load cell (UT-10 manufactured by Minebea Co., Ltd.).
0GR), and among the displayed numerical values, the maximum value when the rotational speed was increased was determined as the friction coefficient. This was defined as the friction coefficient between the flying magnetic head and the magneto-optical recording medium, and measurement and recording were performed for each rotation.

FIG. 1 shows the friction coefficient for each rotation recorded in the CSS test. The initial coefficient of friction was as good as 0.05, and the lubricity was as good as 0.08 even after 10,000 CSS tests. In other words, the present lubricating layer has excellent lubricity and wear resistance as a thin film, and the magneto-optical recording medium using the lubricating layer has good lubricity and sufficient durability, and is unlikely to be attracted to the flying magnetic head. Was.

Example 2 5 g of styrene, 9.1 g of 55% pure divinylbenzene (others were ethylvinylbenzene), 1H, 1H, 2H, 2H
5 g of hexadecafluorodecyl acrylate and 0.5 g of azoisobutyronitrile were dissolved in 100 mL of heptane, and heated at 70 ° C. for 7 hours under nitrogen while stirring.

With time, the reaction system became cloudy due to the formed styrene-divinylbenzene copolymer fine particles. After completion of the reaction, the solvent portion was removed, and the porous crosslinked vinyl polymer-based fine particles were impregnated with a lubricant (hexadecafluorodecyl acrylate), and partially obtained as copolymerized fine particles. 5 parts by weight of the fine particles impregnated with the lubricant are added to 100 parts by weight of an ultraviolet curable resin (HOD-1011, manufactured by Nippon Kayaku Co., Ltd.), and the mixture is treated with an ultrasonic homogenizer (BRANSON SONIFIER 450).
Dispersed for minutes. The resin thus obtained did not undergo phase separation even after standing for 3 months.

A lubricating layer was formed on a magneto-optical recording medium in the same manner as in Example 1 except that this resin was used. When a CSS test was performed on this medium, the initial friction coefficient was as good as 0.05, and there was no change in the friction coefficient up to 10,000 times of the CSS test. In other words, the present lubricating layer has excellent lubricity and wear resistance as a thin film, and the magneto-optical recording medium using the lubricating layer has good lubricity and sufficient durability, and is unlikely to be attracted to the flying magnetic head. Was.

Example 3 5 g of styrene, 9.1 g of 55% pure divinylbenzene (others are ethylvinylbenzene), and alkoxy-modified polydimethylsiloxane (KF-85 manufactured by Shin-Etsu Chemical Co., Ltd.)
1) 5 g and 0.5 g of azoisobutyronitrile are dissolved in 100 mL of heptane, and stirred under nitrogen for 70 minutes.
Heated at 7 ° C. for 7 hours. With time, the reaction system became cloudy due to the formed styrene-divinylbenzene copolymer fine particles. After completion of the reaction, the solvent portion was removed to obtain fine particles obtained by impregnating a porous crosslinked vinyl polymer-based fine particle with a lubricant (alkoxy-modified polydimethylsiloxane).

5 parts by weight of the fine particles impregnated with the lubricant were added to 100 parts by weight of an ultraviolet curable resin (HOD-1011, manufactured by Nippon Kayaku Co., Ltd.), and the mixture was treated with an ultrasonic homogenizer (BRANSON SONIFIER 450).
Dispersed for minutes. The resin thus obtained did not undergo phase separation even after standing for 3 months. A lubricating layer was formed on a magneto-optical recording medium in the same manner as in Example 1 except that this resin was used.

When a CSS test was performed on this medium,
The initial coefficient of friction was as good as 0.05.
There was no change in the coefficient of friction down to 000 cycles. In other words, this lubrication layer shows excellent lubricity and wear resistance in a thin film,
A magneto-optical recording medium using this had good lubricity and sufficient durability, and was less likely to be attracted to a flying magnetic head.

Example 4 A methacryl-modified dimethylsiloxane having a number average molecular weight of 4700 (X-22-174DX, Shin-Etsu Chemical Co., Ltd.)
) Was dissolved in 100 mL of heptane, and heated at 70 ° C for 7 hours under nitrogen with stirring to give a lubricant (methacrylic) to the porous crosslinked vinyl polymer fine particles. Modified dimethyl siloxane)
Were impregnated and partially copolymerized to obtain fine particles. The average particle size was 20 μm.

5 parts by weight of the fine particles impregnated with the lubricant were added to 100 parts by weight of an ultraviolet curable resin (HOD-1011, manufactured by Nippon Kayaku Co., Ltd.), and the mixture was treated with an ultrasonic homogenizer (BRANSON SONIFIER 450).
Dispersed for minutes. A lubricating layer was formed on a magneto-optical recording medium in the same manner as in Example 1 except that this resin was used. When the thickness of the lubricating layer was less than 60 μm, a visually recognizable stripe pattern was formed, suggesting that the unevenness of the lubricating layer was not uniform. Therefore, a 70 μm lubricating layer was formed.

When a CSS test was performed on this medium,
The initial coefficient of friction is 0.1 and has lubricity.
There was no change in the coefficient of friction up to 10000 SS tests. However, when the rotation speed of the medium increases, 3600 RP
During rotation at M and when the number of rotations decreased, there was no significant change in the friction coefficient, suggesting that the head did not float from the medium. It was also suggested that the lubricating layer had a thickness of 70 μm, which was not suitable for magnetic field modulation recording by a magnetic head.

Comparative Example 1 The same composition as in Example 1 except that methacryl-modified dimethylsiloxane was not used was dissolved in 100 mL of heptane, and heated at 70 ° C. for 7 hours under nitrogen while stirring to obtain a porous crosslinked vinyl polymer. Fine particles were obtained. The average particle size was 50 μm. In this case, the porous crosslinked vinyl polymer-based fine particles are not impregnated with the lubricant at all.

5 parts by weight of these fine particles were mixed with an ultraviolet curable resin (H
100 parts by weight of OD-1011 (manufactured by Nippon Kayaku Co., Ltd.) and an ultrasonic homogenizer (BRANSON SONI)
(FIER 450) for 30 minutes. A lubricating layer was formed on a magneto-optical recording medium in the same manner as in Example 1 except that this resin was used.

When a CSS test was performed on this medium,
The initial coefficient of friction exceeds 1.0 and does not have lubricity,
I couldn't continue testing.

[0091]

According to the present invention, a thin film having excellent lubricity
As a result of having abrasion resistance, preventing aggregation of the lubricant and suppressing spin-off, a highly reliable lubricating layer capable of maintaining excellent durability for a long period of time is obtained. In particular, when a smooth substrate corresponding to the low flying height of the head is used, it has good lubricity and sufficient durability without causing adsorption to the head. By applying the lubricating layer according to the present invention to the information recording medium, it becomes possible to increase the data recording density by reducing the flying height of the head,
An information recording medium and an information recording device with high reliability over a long period can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in a coefficient of friction of a magneto-optical recording medium of Example 1 by a CSS test.

FIG. 2 is a diagram showing an example of a recording / reproducing apparatus using the optical disc of the present invention.

[Explanation of symbols]

 11, 11 ', 11 "optical disk 12, 12', 12" optical head 13, 13 ', 13 "optical head 14 support arm

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 5/72 G11B 5/72 5/84 5/84 B // C10N 20:06 40:18 F term ( 4H104 CA08A CB08A CB12A CB13A CD04A CJ02A CJ10A CJ11A CJ12A EA03A EA08A PA16 PA50 RA03 5D006 AA01 AA02 AA06 DA03 FA02 FA06 5D075 EE03 FG10 FG15 5D112 AA07 AA12 BC02 BC08 BC08

Claims (9)

[Claims] 1. A lubricating layer comprising porous crosslinked vinyl polymer-based fine particles impregnated with or copolymerized with a lubricant and a curable resin. 2. The lubricating layer according to claim 1, wherein the fine particles have an average particle size of 10 μm or less. 3. The lubricant has a number average molecular weight of 1,000.
～20000 of modified unprotected polyorganosiloxanes also, or in the backbone -C _a F _2a O- units (where, a
The lubricating layer according to claim 1, wherein the lubricating layer is any one of a perfluoropolyether having an integer of 1 to 4) and a perfluoroalkyl compound which may be modified. 4. The lubricant has a number average molecular weight of 1,000.
Alkoxy-modified products of polyorganosiloxane ～20000, polyether-modified product, or (meth) acrylic-modified product, or a main chain -C _a F _2a O- units (wherein, a is 1
Perfluoropolyether having a terminal ester bond of a functional group having to 4 integer) -C _b F _2b or the main chain,
The lubricating layer according to claim 3, wherein the lubricating layer is a compound having a unit (where b is an integer of 1 to 15) and having a functional group of an ester bond at a terminal. 5. The fine particles have a number average molecular weight of 1,000.
Radical polymerizable silicone macromonomer having an ethylenically unsaturated group at one terminal of the polyorganosiloxane ～20000 or backbone -C _b F _2b, - units (wherein, b
The lubricating layer according to any one of claims 1 to 3, wherein any one of compounds having a (meth) acrylate group at a terminal is copolymerized. 6. An information recording medium provided with the lubricating layer according to claim 1. 7. A method for producing an information recording medium, comprising applying a curable resin containing porous crosslinked vinyl polymer-based fine particles impregnated or copolymerized with a lubricant, and then curing the resin. 8. An information recording device comprising an information recording medium provided with the lubricating layer according to claim 1 and a floating head or a contact head. 9. An information recording device comprising an information recording medium provided with a lubricating layer according to claim 1 and a flying head.