JPH09100422A - Ultraviolet-curable coating composition, magnet-optical disk using the same and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ultraviolet-curable coating composition, excellent in lubrication on the surface of the protective coat, good in sliding resistance, having high retention of reliability and capable of producing magnet-optical disks at low cost, by formulating a (meth)acrylic ester, a photopolymerizable prepolymer, an optical polymerization initiator and an organic polysiloxane in a specific proportion. SOLUTION: This composition contains (A) 100 pts.wt. of a (meth)acrylic ester, suitably lauryl (meth)acrylate, (B) 30-80 pts.wt. of a photopolymerizable prepolymer, suitably a urethane (meth)acrylate, epoxy (meth)acrylate, etc., (C) 10-40 pts.wt. of a photopolymerization initiator, (D) 0.1-10 pts.wt. of an organic polysiloxane, suitably a compound of the formula (m and n are each >=0.1; X and Y are each an alkyl, a higher fatty acid ester). In addition, the following components is preferably contained: (E) 0.1-10 pts.wt. of a fatty acid ester and (F) 0.1-10 pts.wt. of an organic compound having a fluoroalkyl or an unsaturated aliphatic alkyl group as a side chain on the chain terminal of its molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a UV-curable coating material for use as a protective coating having a sliding resistance on a magneto-optical disk for recording by a magnetic field modulation method, a magneto-optical disk using the same, and a manufacturing method thereof. Regarding the method.

[0002]

2. Description of the Related Art In recent years, magneto-optical disks have been attracting attention as high-density recording media. The magneto-optical disk is an optically transparent substrate on which guide grooves of substantially concentric circles are formed,
In many cases, a structure in which a protective layer, a magneto-optical recording layer, a protective layer, a reflective layer, and a protective coat are sequentially formed is used. The substrate is composed of an optically transparent material such as polycarbonate. The magneto-optical recording layer is formed by thinning an amorphous alloy of a rare earth metal and a transition metal having a perpendicular magnetic anisotropy and a magneto-optical effect such as TbFeCo. The protective layer is composed of a silicon nitride film or the like and is necessary for preventing the oxidation of the magneto-optical recording layer. The reflective layer is formed of a thin film of aluminum or an alloy containing aluminum as a main component, and is provided for improving the detection efficiency of a reproduced signal and controlling thermal diffusion. The protective coat is formed of an ultraviolet curable resin composed of a photopolymerization initiator, a photopolymerizable prepolymer, and (meth) acrylic acid ester, and is used to prevent moisture from entering the magneto-optical recording layer.

A recording device for writing an information signal on such a magneto-optical disc includes an optical pickup device for irradiating the magneto-optical disc with a laser beam and a magnetic field applying device for applying an external magnetic field to the magneto-optical disc. A mechanism for rotating the magneto-optical disk, a means for moving the optical pickup device, and a mechanism for moving the magnetic field applying device.

The optical pickup device comprises a light source such as a semiconductor laser and a predetermined optical device for guiding and condensing a light beam emitted from the light source. The optical pickup device is arranged at a position separated from the magneto-optical disk by a certain distance, and converges and irradiates a light flux on the magneto-optical recording layer of the magneto-optical disk. The irradiation of the light flux is performed through the substrate from the back side of the main surface portion of the substrate of the magneto-optical disk on which the magneto-optical recording layer is formed. In the optical pickup device, when the light output of the light flux is modulated, the light emission output of the semiconductor laser or the like is modulated by the drive circuit or the like.
A method of writing an information signal by modulating the optical output of the light flux is called an optical modulation method.

On the other hand, as the magnetic field applying device, a magnetic head device having a magnetic field generating coil and a magnetic core around which the coil is wound can be installed. The magnetic head device is arranged at a position close to the magneto-optical disk and applies an external magnetic field to the magneto-optical recording layer of the magneto-optical disk in a direction perpendicular to the surface portion of the magneto-optical recording layer. . The external magnetic field is applied from the main surface portion of the substrate of the magneto-optical disk on the side where the magneto-optical recording layer is formed. In this magnetic head device, in order to modulate the strength and direction of the external magnetic field, the current supplied to the magnetic field generating coil is modulated by a drive circuit or the like. A recording method for writing an information signal by modulating the strength and direction of the external magnetic field in this manner is called a magnetic field modulation method.

The advantage of the magnetic field modulation system over the optical modulation system is that an initialization operation for preliminarily aligning the magnetization direction of the recording film in one direction is not necessary before writing the information signal, and that information can be overwritten. It is suitable for mark length recording.

Although a method of overwriting information in the optical modulation method has been proposed, such a magneto-optical disk is complicated because the magneto-optical recording layer is composed of a plurality of magnetic thin films, and the manufacturing is complicated. Etc. On the other hand, when the magnetic field modulation method is adopted, overwriting can be easily performed with a magneto-optical disk having a simple structure, and it is about to be widely used.

As described above, in the magnetic field modulation method, the focused laser beam is scanned along the guide groove of the magneto-optical disk, and at the same time, the externally applied magnetic field is modulated to irradiate the laser beam of the magneto-optical recording layer. This is a method of recording by changing the direction of magnetization of the formed portion. The magnetic field necessary for reversing the magnetization of the magneto-optical recording layer needs to change its direction and intensity at a relatively high frequency (several hundreds of kHz or more), and such magnetic field is generated by the magnetic head device. Limited to the vicinity of the core. Therefore, it is necessary to make the distance between the laser light irradiation portion of the magneto-optical recording layer of the magneto-optical disk and the magnetic head device as short as possible.

As a method for arranging the magnetic head device in such a state, it is considered that the magneto-optical disk is rotated while the magnetic head device is placed in contact with the magneto-optical recording layer. To be That is, if the magneto-optical disk is rotated while the magnetic head device is pressed against the magneto-optical disk with a spring or the like,
The magnetic head device is always in sliding contact with the magneto-optical disc, the distance of the magneto-optical disc from the magneto-optical recording layer is constant, and the magnetic head device is located closest to the magneto-optical recording layer.

However, when the magnetic head device is brought into sliding contact with the magneto-optical disk in order to apply an external magnetic field to the magneto-optical recording layer of the magneto-optical disk, the protective coat of the magneto-optical disk and the magnetic head device. The frictional force generated during the operation may increase the load on the rotating operation, and may damage the magnetic head and the protective coat due to abrasion. Therefore, several methods have been proposed for reducing the frictional force between the protective coat and the magnetic head device.

The contents described in Japanese Patent Laid-Open No. 05-307777 will be described as a first conventional example of this method. The structure is such that a lubricant layer made of silicone oil is formed on the protective coat of the magneto-optical disk. The forming method is to install a coating member such as a non-woven fabric impregnated with a lubricant diluted with a solvent on the protective coat forming surface of the magneto-optical disk, and press the coating member onto the protective coat of the magneto-optical disk with a press machine. Then, a lubricant layer is formed on the protective coat of this magneto-optical disk.

A second conventional example is Japanese Patent Laid-Open No. 05-
The contents described in Japanese Patent No. 163564 will be described.
The structure is such that a lubricant layer formed of a fluorocarbon lubricating oil containing fluorine and carbon as main components having one or more active polar groups is provided on the protective coat of the magneto-optical disk. The formation method is as follows: A protective coat formed of an organic resin is spin-coated on a surface of a protective coat formed by dissolving polyfluorocarbon lubricating oil in isopropyl alcohol, and then heated at 80 ° C. to remove a solvent. The lubricant layer is formed by evaporation.

As a third conventional example, a method of impregnating a protective coat of the magneto-optical disk with a lubricant can be exemplified. Japanese Unexamined Patent Publication (Kokai) No. 64-043834 discloses a structure in which a polymer sheet impregnated with a lubricant composed of fatty acid or ester or a mixture thereof is formed on a protective coat by adhesion on the thin film layer of the magneto-optical disk. ing. Further, JP-A-63-098857 discloses that
A fluorocarbon-based lubricant is disclosed as a lubricant to be impregnated, a reactive silicone compound is disclosed as a lubricant to be impregnated in JP-A 03-160642, and an impregnation is disclosed in JP-A 04-209346. An example in which a perfluoropolyether having an isocyanate group at the end is polymerized and used as a lubricant is disclosed.

[0014]

However, the above-mentioned conventional magneto-optical discs by the three methods capable of magnetic field modulation recording have problems such as complexity of the manufacturing process and lack of sliding durability.

That is, in the first conventional example, when the solvent used for diluting the lubricant volatilizes, it reacts with the polycarbonate that constitutes the substrate of the magneto-optical disk to reduce the light transmittance of the substrate. There are challenges. In addition to the conventional equipment for manufacturing magneto-optical discs, equipment for collecting volatilized solvent for explosion protection is required, and there is also the problem that press equipment must be added. Difficult to offer at a price.

Further, in the second conventional example, the heating equipment for evaporating the solvent used for diluting the lubricant and the equipment for recovering the explosion-proof evaporative solvent are the equipment for manufacturing the conventional magneto-optical disk. Is necessary in addition to.

Further, in the third conventional example, by simply mixing the fatty acid ester lubricant, the fluorocarbon lubricant and the reactive silicone compound lubricant alone, the frictional force in the initial characteristics can be reduced. Is effective, but there is a problem that frictional force increases in a high temperature and high humidity environment, and sliding durability cannot be ensured.

In order to solve the above-mentioned conventional problems, the present invention has excellent lubricity on the surface of the protective coat, good sliding resistance, long-term reliability, and manufacturing cost. It is an object of the present invention to provide an ultraviolet-curable coating composition for producing a low magneto-optical disc, a magneto-optical disc using the same, and a method for producing the same.

[0019]

In order to achieve the above object, the ultraviolet-curable coating composition of the present invention comprises a (meth) acrylic acid ester, a photopolymerizable prepolymer, a photopolymerization initiator, and an organic polysiloxane. In the ultraviolet curable coating composition containing, the composition ratio of each component is (a) (meth) acrylic acid ester 100 parts by weight (b) photopolymerizable prepolymer 30 to 80 parts by weight (c) photopolymerization initiator 10 to 40 Parts by weight (d) Organic polysiloxane 0.1 to 10 parts by weight.

Here, the (meth) acrylic acid ester means
It contains acrylic acid ester and methacrylic acid ester. The organic polysiloxane refers to one having a molecular structure represented by the above formula (Formula 1), and various modified products may exist depending on the side chains X and Y.

In the above formula (Formula 1), side chains X and Y which can be preferably used in this embodiment include, for example, an alkyl group, a higher fatty acid ester group, a methylchlorinated phenyl group and an alkyl group having 4 to 18 carbon atoms. A linear or branched molecular chain having a group, a methylphenyl group and the like. The side chains X and Y may be the same as or different from each other. The organically modified polysiloxane may be a polymethylsiloxane represented by the following formula (formula 2) and the following formula (formula 3). The polymethylsiloxane may be one kind or a combination of plural kinds.

[0022]

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[0023]

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In the above constitution, 0.1 part of the fatty acid ester is added to 100 parts by weight of the (meth) acrylic acid ester.
It is preferable to add 10 to 10 parts by weight. Also in this case,
It is preferable to add 0.1 to 10 parts by weight of an organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end with respect to 100 parts by weight of a (meth) acrylic acid ester. The fluoroalkyl group as used herein includes saturated or unsaturated type.

Further, in the above constitution, the photopolymerizable prepolymer is preferably at least one selected from urethane (meth) acrylate and epoxy (meth) acrylate. Here, the urethane (meth) acrylate refers to a compound synthesized by reacting an organic compound having an isocyanate group with a (meth) acrylate having a hydroxy group and a polyester. Also epoxy (meta)
The acrylate is a compound obtained by esterifying the epoxy group of a phenol novolac type, bisphenol A type, or alicyclic epoxy resin with (meth) acrylic acid to make the functional group an acryloyl group.

In the above-mentioned constitution, the (meth) acrylic ester is lauryl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, At least one selected from tricyclodecanyl (meth) acrylate, triethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and hexanediol di (meth) acrylate is preferable.

In the above structure, it is preferable that the aliphatic alkyl group of the fatty acid ester has 10 to 18 carbon atoms. In the above-mentioned constitution, it is preferable that the organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at a molecular end (hereinafter referred to as an alkyl group-containing organic compound) is a fatty acid alkyl succinic acid diester. Here, the fatty acid alkyl succinic acid diester refers to one represented by the following formula (Formula 4).

[0028]

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In the above constitution, the viscosity at 25 ° C.
Is preferably 20 to 100 centipoise. Next
The method of manufacturing a magneto-optical disk of the present invention is optically transparent.
Magneto-optical recording layer consisting of a thin film of an inorganic compound on a transparent substrate
A protective layer formed of an organic compound on the magneto-optical recording layer.
In the manufacturing method of the magneto-optical disk for forming the protective coating layer
(A) (meth) acrylic acid ester 100 parts by weight (b) photopolymerizable prepolymer 30 to 80 parts by weight (c) photopolymerization initiator 10 to 40 parts by weight (d) organic polysiloxane 0.1 to 10 Apply an ultraviolet curable paint consisting of parts by weight to the thin film,
Illuminance is 300 mW / cm ^Two1000 mW / cm or more^TwoLess than
In the lower range, the light intensity is 500 mJ / cm^TwoMore than 150
0mJ / cm^TwoThe ultraviolet rays in the range below are
Irradiate the chemical paint to cure the paint and form a protective coat layer
It is characterized by doing.

In the above manufacturing method, it is preferable that the ultraviolet-curable coating material is applied to the thin film of the inorganic compound in a thickness of 5 to 50 μm. In the manufacturing method, it is preferable that the fatty acid ester is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester.

Further, in the above-mentioned production method, 0.1 to 10 parts by weight of an organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at a molecular end is added to 100 parts by weight of (meth) acrylic acid ester. It is preferable to include a part.

In the above production method, it is preferable that the photopolymerizable prepolymer is at least one selected from urethane (meth) acrylate and epoxy (meth) acrylate.

Further, in the above production method, the (meth) acrylic acid ester is lauryl (meth) acrylate,
Ethoxydiethylene glycol (meth) acrylate,
Phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, triethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate,
And at least one selected from hexanediol di (meth) acrylate.

In the above-mentioned production method, the aliphatic alkyl group of the fatty acid ester has 10 to 18 carbon atoms.
It is preferable to be within the following range. Further, in the above-mentioned production method, it is preferable that the organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end is a fatty acid alkylsuccinic acid diester.

In the above production method, the (meth) acrylic acid ester is preferably an acrylic acid ester or a methacrylic acid ester. Moreover, in the said manufacturing method, it is preferable that the viscosity in 25 degreeC is 20-100 centipoise.

Further, in the above-mentioned manufacturing method, it is preferable that the organic polysiloxane is of the above formula (Formula 1). Next, the magneto-optical disk of the present invention has a magneto-optical recording layer formed of a thin film of an inorganic compound on an optically transparent substrate,
In a magneto-optical disk in which a protective coating layer made of an organic compound is formed on the magneto-optical recording layer, the organic compound is (a) (meth) acrylic acid ester 100 parts by weight (b) photopolymerizable prepolymer 30 to 80 Parts by weight (c) photopolymerization initiator 10 to 40 parts by weight (d) organically modified polysiloxane 0.1 to 10 parts by weight, which is a cured product of an ultraviolet curable coating material.

In the magneto-optical disk, it is preferable that the thickness of the protective coat made of an organic compound is in the range of 5 to 50 μm. The magneto-optical disk preferably contains 0.1 to 10 parts by weight of fatty acid ester with respect to 100 parts by weight of (meth) acrylic acid ester.

In the magneto-optical disk, an organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end is added to 0.1 to 10 parts by weight of (meth) acrylic acid ester. It is preferable to include parts by weight.

In the magneto-optical disk, the photopolymerizable prepolymer is preferably at least one selected from urethane (meth) acrylate and epoxy (meth) acrylate.

In the magneto-optical disk, the (meth) acrylic acid ester may be lauryl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate or isobornyl (meth) acrylate. ) It is preferably at least one selected from acrylate, tricyclodecanyl (meth) acrylate, triethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and hexanediol di (meth) acrylate.

In the magneto-optical disk, the aliphatic alkyl group of the fatty acid ester preferably has 10 to 18 carbon atoms. Further, in the magneto-optical disk, the organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end is preferably a fatty acid alkyl succinic acid diester.

In the magneto-optical disk, the (meth) acrylic acid ester is preferably acrylic acid ester or methacrylic acid ester. Further, in the magneto-optical disk, the organic polysiloxane is preferably represented by the above formula (Formula 1).

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION The photopolymerizable prepolymer constituting the protective coat of the magneto-optical disk of the present invention constitutes the main structure of the protective coat. By adding the (meth) acrylic acid ester, it becomes easy to form the composition paint in the form of a thin film of 5 to 50 μm. That is, the photopolymerizable prepolymer generally has a high viscosity, and it is difficult to form a thin film having a thickness of 50 μm or less by a spin coater device which is usually used for producing a protective coat of an optical disc. Therefore, the viscosity of the composition coating is reduced by mixing a (meth) acrylic acid ester having at least one functional group selected from monofunctional and bifunctional ones having a low viscosity, and the composition coating composition is formed into a thin film of 5 to 50 μm in a spin coater device. Can be easily formed. In the above, the monofunctional (meth) acrylic acid ester means that the end of the ester group has no reactivity,
The bifunctional (meth) acrylic acid ester refers to one having a terminal of an ester group such as a reactive —OH group. Further, a compound having an acryl group or a methacryl group at both terminals such as di (meth) acrylic acid ester is also a bifunctional substance.

The organically modified polysiloxane contained in the protective coat improves the lubricity and scratch resistance of the surface of the protective coat of the photopolymerizable prepolymer and the (meth) acrylic acid ester, and improves the abrasion resistance. The fatty acid ester is effective in reducing frictional force. The alkyl-containing organic compound improves the sliding property under high temperature and high humidity environment due to the combined effect with the fatty acid ester.

FIG. 1 is a schematic sectional view showing the structure of the magneto-optical disk of this embodiment. The magneto-optical disk is an optically transparent disc-shaped substrate 1 made of polycarbonate, for example.
0, the first protective layer 11 formed on the substrate 10, the magneto-optical recording layer 12 formed on the first protective layer 11, the second protective layer 13 formed on the magneto-optical recording layer 12, and the second protective layer 13. Protective layer 13
The reflective film 14 is formed on the reflective film 14, and the protective coat 15 is formed on the reflective film 14. For example, the protective layers 11 and 13 have SiN as a main component. The magneto-optical recording layer 12 contains TbFeCoCr as a main component. Reflective film 1
4 has AlTi as a main component.

The substrate 10 can be formed by using glass, polymethylpentene, or the like which is optically transparent and has excellent dimensional stability, other than polycarbonate. Substrate 10
A groove or an uneven pit is formed on at least one surface of the above along substantially concentric circles. The groove formed on the substrate 10 has a main role as a guide groove for guiding the condensed laser light beam, and the pits having irregularities are used for recording position information or the like for moving the laser light beam to an arbitrary position. The substrate 10 is produced by replicating from a master to form grooves and concave / convex pits. The master disk is a disk-shaped glass plate with a clean surface, coated with a photosensitive resin using a spinner method, etc., and the light is partially irradiated on the areas where grooves and concave / convex pits are formed on the photosensitive resin. The steps of baking, developing and plating to produce a master disc, replicating the mother disc from the master disc, and replicating the stamper from the mother disc are sequentially performed. Polycarbonate, which is a constituent material of the substrate 10, is melted and injection-molded into a space formed by a mold and a stamper installed in the mold to form the substrate 10. The substrate 10 has a diameter of about 65 to 90 mm and a thickness of 0.5 to 1.2 m.
m.

The first protective layer 11 and the second protective layer 13 are
It mainly plays a role of protecting the magneto-optical recording layer 12 from moisture. In addition to this role, the first protective layer 11 has a role of protecting the substrate 10 from heat generated when the focused laser beam is applied to the magneto-optical recording layer 12, and the laser beam has a role of protecting the substrate 10. It also has the function of adjusting so as to be effectively absorbed and reflected. The second protective layer 13 is the magneto-optical recording layer 1 described above.
In addition to the main role of protecting 2 from moisture, the function of adjusting the laser light flux to be effectively absorbed and reflected by the magneto-optical recording layer 12 and the local temperature rise of the magneto-optical recording layer 12 are efficiently performed. As described above, it has a function of adjusting the condition of heat diffusion.

The first protective layer 11 and the second protective layer 13 are
In addition to SiN, SiO_Two, Al_TwoO _Three, Ta_TwoO_Five, T
iO_TwoMetal oxides such as AlN, metal nitrides such as AlN, T
Inorganic carbides such as iC and SiC, AlTaO, ZnS,
ZnSe, ZnSSiO_Two, ZnSeSiO_Two, Above gold
Optical transparency of complex compounds of metal oxides and metal nitrides
Can be made into a thin film.
You.

The magneto-optical recording layer 12 is made of a material having a perpendicular magnetic anisotropy and a magneto-optical effect, and is made of TbFe, T
An amorphous alloy of a rare earth metal and a transition metal such as bFeCo or DyFeCo, or a thin film of a magnetic material having perpendicular magnetization such as MnBi or PtCo can be used. In addition, thin films of each alloy or each elemental metal can be formed in layers and used.

The reflection film 14 is used to reflect the laser light flux transmitted through the magneto-optical recording layer 12. The reflective film 14 is A
A metal such as u, Ag, Pt, Al or an alloy thereof is used in a thin film form. Ta, Ti, Cr, Z as required
A small amount of r, V, Pb, Mo, Pd or the like may be added.

The first protective layer 11, the second protective layer 13, the magneto-optical recording layer 12 and the reflective film 14 are formed by using the vacuum evaporation method or the sputtering method. The thickness of the first protective layer 11 is 80 nm to 120 nm, and the thickness of the magneto-optical recording layer 12 is 1.
The range of 0 nm to 50 nm, the second protective layer 13 is 5 nm
To 30 nm, the reflection film 14 is 20 nm to 60 n
It is preferably in the range of m.

The protective coat 15 has a function of protecting the reflective film 14 from mechanical damage, a function of preventing moisture or the like from directly contacting the reflective film 14, and a frictional force against the sliding magnetic head which impedes the rotation operation. This is to ensure the function of reducing the damage to the extent that there is no damage and the function of preventing the magnetic head and the protective coat 15 from being broken due to wear. Protective coat 15
Is formed by applying an ultraviolet curable coating on the reflective film 14 using a spin coating method or a screen printing method and irradiating ultraviolet rays.

Next, the constituent components of the ultraviolet-curable coating composition of this example will be described in detail. The photopolymerizable prepolymer, which is a constituent of the UV-curable coating composition for forming the protective coat 15 of the magneto-optical disk of the present example, constitutes the main structure of the protective coat 15. The photopolymerizable prepolymer may be polyester acrylate, silicon acrylate, melamine acrylate, urethane acrylate, epoxy acrylate, etc., but urethane acrylate and epoxy acrylate having hardness and flexibility are preferable. More preferably,
Epoxy acrylate is used to reduce the viscosity of the UV curable paint.

Protective coat 1 for the magneto-optical disk of this embodiment
The monofunctional acrylic acid ester, which is a constituent of the UV-curable coating composition for constituting No. 5, is for reducing the viscosity of the photopolymerizable prepolymer and for ensuring the adhesion between the reflective film 14 and the protective coat 15. Used for. As monofunctional acrylic acid ester, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, lauryl methacrylate, diethylaminoethyl methacrylate, methyl methacrylate, n-bumethyl methacrylate, nonylphenoxyethyl acrylate, tetrahydrofurfuryloxyethyl Acrylate, cyclohexaneoxyethyl acrylate, tetrahydrofurfuryloxyhexanolide acrylate, 1,3-dioxolane acrylate, tricyclodecanyloxy acrylate, isoamyl acrylate, stearyl acrylate, butoxyethyl acrylate, methoxytriethylene glycol acrylate, methoxydipropylene glycol Acrylate, phenoxy polyethylene glycol Acrylate, isobornyl acrylate, lauryl acrylate, ethoxy diethylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, can be utilized tricyclodecanyl acrylate. For improving weather resistance and adhesion, lauryl acrylate, ethoxydiethylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, tricyclodecanyl acrylate can be used alone or in combination.

Protective coat 1 for the magneto-optical disk of this embodiment
The bifunctional acrylic acid ester, which is a constituent of the UV-curable coating composition for constituting No. 5, is used for reducing the viscosity of the photopolymerizable prepolymer and increasing the polymerization reaction rate. As the bifunctional acrylic acid ester, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate,
Diethylene glycol diacrylate, polyethylene glycol diacrylate, tricyclodecane dimethylol diacrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate, hexanediol diacrylate, etc. can be used.
In order to improve the dilutability, triethylene glycol diacrylate, neopentyl glycol diacrylate, and hexanediol diacrylate can be used alone or in combination.

As the acrylic acid ester, a monofunctional acrylic acid ester may be used alone, a bifunctional acrylic acid ester may be used alone, or a monofunctional acrylic acid ester and a bifunctional acrylic acid ester may be used. Acrylic ester may be used together. Further, the acrylic acid ester may be a methacrylic acid ester in which H is replaced with a methyl group. Also, the viscosity of the UV curable coating at 25 ° C is 10
You may add trifunctional or more than trifunctional (meth) acrylic acid ester in the range which does not exceed 0 centipoise. Trimethylpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate and the like can be used as the trifunctional or higher functional (meth) acrylic acid ester to be added.

Protective coat 1 for the magneto-optical disk of this embodiment
The fatty acid ester, which is a constituent element of the ultraviolet-curable coating material for forming No. 5, is used to reduce the frictional force on the surface of the protective coat 15. Fatty acid esters include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid,
Stearic acid, oleic acid, adipic acid, sebacic acid,
It is composed of an ester bond formed by the reaction of an alcohol such as maleic acid with an alcohol. Among these fatty acid esters, fatty acid esters in which capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, etc., which have 10 to 18 carbon atoms are reacted with alcohol are particularly preferable.

As the organic compound having an alkyl group, fatty acid alkyl succinic acid diester, fatty acid alkyl succinic acid monoester, fatty acid alkyl succinic acid triester and the like can be used. Acetophenone, trichloroacetophenone, dichloroacetophenone, tert-butyltrichloroacetophenone, 2,2-diene as a photopolymerization initiator which is a constituent of the ultraviolet curable coating material for forming the protective coat 15 of the magneto-optical disk of the present example. Ethoxyacetophenone, 4-dialkylaminoacetophenone, p, p
′ -Dimethylaminoacetophenone, p-dimethylaminopropiophenone and other acetophenones, benzophenone, 2-chlorobenzophenone, p, p′-dichlorobenzophenone, p, p′-bisdiethylaminobenzophenone,
Benzophenone-based compounds such as 4,4-bisdimethylaminobenzophenone (Michler's ketone), ketone-based compounds such as benzyl, benzyl dimethyl ketal, phenyl methoxy ketone, 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoylbenzoate, benzoyl peroxide, benzoin isobutyl ether, Benzoin -n-
Butyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether,
Benzoin such as benzoin-n-propyl ether, thioxanthone, 2-chlorothioxanthone, methylbenzoyl formate, α-acyloxime ester, 2,4
-Diethylthioxanthone, 2-chlorothioxanthone,
Thioxanthone compounds such as 2-methylthioxanthone, and p-acetyl, tetramethylthiuram sulfide, azobisisobutyronitrile, di-tert-butyl peroxide, 2-hydroxy-2-methyl-1-phenyl-propane-
1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2,2-dimethoxy-
1,2-diphenylethan-1-one and the like can be used alone or in combination. Acetophenone, p, p'-dimethylaminoacetophenone, 2,2-diethoxyacetophenone, benzophenone, 4,4-bisdimethylaminobenzophenone, benzyl, benzyldimethylketal, and phenylmethoxy are preferable in terms of compatibility with light absorption wavelength. Ketone, 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin isobutyl ether, piacetyl, tetramethyl thiuram sulfide,
Azobisisobutyronitrile, di-tert-butyl peroxide, thioxanthone, 2,4-diethylthioxanthone, 2,2-dimethoxy-1,2-diphenylethan-1-one, etc. are used alone or in combination. Good to do.

As described above, a photopolymerizable prepolymer, an acrylate ester, an organically modified polysiloxane,
An ultraviolet curable coating material using a photopolymerization initiator and, if necessary, a fatty acid ester and an organic compound containing an alkyl group is applied onto the reflective film 14 by spin coating, and irradiated with ultraviolet rays to form a protective coat. . In the spin coating method, an appropriate amount of UV-curable coating material is applied to the center of the coating surface, and then the coating surface is rotated at a relatively high speed to apply the applied UV-curing coating material to the entire coating surface. It is a method of expanding.
And a spin coater for carrying out it is a nozzle device for applying paint, a tank for storing the paint, a pipe for transporting the paint from the tank to the nozzle device, and a predetermined amount of the paint for applying from the nozzle. The control device, the rotary table device for rotating the surface to be coated, the outer wall installed so as to cover the rotary table device, and the recovery device for recovering the paint adhering to the outer wall.

Protective coat 1 for the magneto-optical disk of this embodiment
5 is formed, the first protective layer 11 and the magneto-optical recording layer 1 are formed.
2. The substrate 10 on which the second protective layer 13 and the reflective film 14 are sequentially formed is arranged so that the nozzle device and the surface on which the reflective film 14 is formed face each other, and the nozzle of the nozzle device is located near the center of the substrate 10. To place. Next, the substrate 10 is rotated at a rotational speed of 10 to 100 revolutions per minute, and an appropriate amount of the ultraviolet curable coating material is applied from the nozzle. After that, when the substrate 10 is rotated at a rotation speed of 2000 rpm to 5000 rpm, the ultraviolet curable coating material applied to the central portion of the substrate 10 is expanded and spread in the outer peripheral direction of the substrate by centrifugal force. The ultraviolet curable coating remains on the reflective film 14 of the substrate 10 in a thickness of 5 to 50 μm, and the coating is completed.

At this time, 95% or more of the ultraviolet-curable coating material applied on the substrate 10 reaches the outer wall of the spin coater by the action of centrifugal force, and less than 5% is actually applied. Therefore, in order to effectively use the ultraviolet curable resin, it is necessary to collect and use the ultraviolet curable coating adhered to the outer wall. In order to carry out this recovery efficiently, it is preferable that the viscosity of the ultraviolet curable paint is low. As a result of earnest studies, the present inventors established that when the viscosity of the ultraviolet curable coating exceeds 100 centipoise, problems such as clogging and air bubble generation occur during transportation and filtering of the ultraviolet curable coating attached to the outer wall. Has been revealed to increase.

In this example, 30 to 80 parts by weight of a photopolymerizable prepolymer and 100 parts by weight of a (meth) acrylic acid ester were used so that the viscosity of the ultraviolet curable coating composition would not exceed 100 centipoise. The initiator is adjusted to 10 to 40 parts by weight and the organically modified polysiloxane is adjusted to 0.1 to 10 parts by weight to form an ultraviolet curable coating material. Furthermore, in addition to the above composition, 0.1 to 1 of fatty acid ester is added.
You may add 0 weight part. When the fatty acid ester is added, 0.1 to 5 parts by weight of the alkyl-containing organic compound may be added. The organically modified polysiloxane is used to secure the lubricity and scratch resistance of the surface of the protective coat 15,
The fatty acid ester is used to reduce the frictional force on the surface of the protective coat 15, and the alkyl group-containing organic compound is used to improve the sliding characteristics in a hot and humid environment due to the combined effect with the fatty acid ester. Since these elements ensure the lubricity and the sliding resistance of the surface of the protective coat 15 due to the synergistic effect of each other, the balance of the respective constituent elements is important. The composition of the paint can be analyzed by a nuclear magnetic resonance method or the like before curing. When the amount of the photopolymerizable prepolymer with respect to 100 parts by weight of the (meth) acrylic acid ester is less than 30 parts by weight, the mechanical strength of the protective coat 15 becomes insufficient, and 8
If it exceeds 0 parts by weight, the viscosity of the ultraviolet curable coating composition exceeds 100 centipoise. Further, when the amount of the photopolymerization initiator is less than 10 parts by weight, the polymerization reaction of the photopolymerizable prepolymer becomes insufficient, and when it exceeds 40 parts by weight, the photopolymerization initiator remains in the protective coat 15 and delays the curing. When the total amount of the organically modified polysiloxane, the fatty acid ester and the organic compound containing an alkyl group exceeds 25 parts by weight, the amount of the lubricant (organic modified polysiloxane, the fatty acid ester and an organic compound containing an alkyl group) present on the surface of the protective coat 15 is increased. It becomes excessive and frictional force becomes large.

[0063]

【Example】

Example 1 An epoxy acrylate, which is a bisphenol A type diepoxy acrylic acid adduct represented by the following formula (formula 5), is used as a photopolymerizable prepolymer, and a monofunctional acrylic ester is represented by the formula (formula 6). And tetrahydrofurfuryl acrylate represented by the following formula (Formula 7)
In combination with tricyclodecanyl acrylate,
Neopentyl glycol diacrylate represented by the following formula (Formula 8) is used as the bifunctional acrylic ester, and two polymethylsiloxanes represented by the following formulas (Formula 9) and (Formula 10) are used as the organic polysiloxane. Mixture (Kyoeisha Chemical Sales brand name "Granol B-14"
84 ") and benzophenone as a photopolymerization initiator and p'p-dimethylaminoacetophenone represented by the following formula (Formula 11) were used to prepare a UV-curable coating composition as described below.

[0064]

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[0065]

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[0066]

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[0067]

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[0068]

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[0069]

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[0070]

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The ultraviolet-curable coating material of this example was prepared by mixing the above-mentioned constituents by changing only the composition of the organic polysiloxane as follows. The viscosity of the paint at 25 ° C was 35 centipoise.

(A) Acrylic ester 100 parts by weight (tetrahydrofurfuryl acrylate: 14 parts by weight, tricyclodecanyl acrylate: 54 parts by weight, neopentyl glycol diacrylate: 32 parts by weight) (b) Photopolymerizable prepolymer 38 parts by weight (c) Photopolymerization initiator 15 parts by weight (benzophenone:
10 parts by weight, p, p-dimethylaminoacetophenone: 5 parts by weight) (d) Polymethylsiloxane 0, 0.5, 1.
0, 1.7, 3.1, 4.6, 6.3, 8.
8 parts by weight The magneto-optical disk of this embodiment has a diameter of about 70 mm and a thickness of 1.
On the 2 mm polycarbonate substrate, the first protective layer 11:
The thickness is 95 nm, the magneto-optical recording layer 12:25 nm, the second protective layer 13:20 nm, and the reflective layer 14:30 nm are formed by the sputtering method. Using a spin coating method, an ultraviolet curable coating material is applied to the reflective film 14 by about 10 μm, and ultraviolet rays (illuminance: 600 mW / cm ² , light quantity:
The protective coat 15 was formed by irradiating with 800 mJ / cm ² .

FIG. 2 shows the dependence of the frictional force of the protective coat 15 of this embodiment on the composition of the organic polysiloxane. The frictional force is the frictional force when the modified polyamide is pressed against the protective coat 15 with a force of 10 mN and the relative speed between the protective coat 15 and the modified polyamide is 1.2 m / sec. The measurement conditions were temperature: 20 ° C., relative humidity: 50% RH, and Max value after sliding for 1 hour.

As is apparent from FIG. 2, when the amount of the organic polysiloxane added is 0.5% by weight, the frictional force sharply decreases,
The frictional force was reduced to 2 parts by weight, and the effect was maintained until the addition of 8.8 parts by weight.

(Example 2) The ultraviolet-curable coating material of this example was prepared by using n-butyl stearate as a fatty acid ester as the constituent component used in Example 1 and changing only the composition as follows. It has been adjusted. The viscosity of the paint at 25 ° C was 35 centipoise.

(A) Acrylic ester 100 parts by weight (tetrahydrofurfuryl acrylate: 14 parts by weight, tricyclodecanyl acrylate: 54 parts by weight, neopentyl glycol diacrylate: 32 parts by weight) (b) Photopolymerizable prepolymer 38 parts by weight (c) Photopolymerization initiator 14 parts by weight (benzophenone:
3. 10 parts by weight, p, p-dimethylaminoacetophenone: 4 parts by weight) (d) 6 parts by weight of polymethylsiloxane (e) n-butyl stearate 0, 3.3, 4.
9, 6.6, 8.2, 9.8 parts by weight Each of the above coating materials was coated in the same manner as in Example 1 with a reflective film 14.
Apply about 10μm on top, and UV light at room temperature (illuminance: 600m
W / cm ² , light quantity: 800 mJ / cm ² ) was irradiated to form a protective coat.

FIG. 3 shows how the frictional force of the Max value changes during sliding for a certain period of time in an environment in which the temperature of the protective coat 15 is 40 ° C. and the relative humidity is 90%. .
As is clear from FIG. 3, the amount of fatty acid ester added was 3.
A stable low frictional force was obtained in the range of 3 to 9.8 parts by weight.

(Example 3) In the ultraviolet-curable coating material of this example, a fatty acid alkyl succinic acid diester represented by the following formula (Formula 12) was used as the alkyl-containing organic compound in the constituent component used in Example 2. However, only the composition was adjusted as follows.

[0079]

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The viscosity of the coating material at 25 ° C. was 35 centipoise. (A) Acrylic ester 100 parts by weight (tetrahydrofurfuryl acrylate: 14 parts by weight, tricyclodecanyl acrylate: 54 parts by weight, neopentyl glycol diacrylate: 32 parts by weight) (b) Photopolymerizable prepolymer 38 parts by weight (C) 13 parts by weight of photopolymerization initiator (benzophenone:
9 parts by weight, p, p-dimethylaminoacetophenone: 4 parts by weight) (d) Polymethylsiloxane 7 parts by weight (e) n-Butyl stearate 7 parts by weight (f) Fatty acid alkyl succinic acid diester 0,
0.8, 3.3, 4.1, 4.9 parts by weight Each of the above coating materials was coated in the same manner as in Example 1 with the reflective film 14.
Apply about 10μm on top, and UV light at room temperature (illuminance: 600m
W / cm ² , light quantity: 800 mJ / cm ² ) was irradiated to form a protective coat.

FIG. 4 shows how the frictional force changes in an environment in which the temperature of the protective coat 15 of this embodiment is 40 ° C. and the relative humidity is 90%. As is clear from FIG. 4, the effect of reducing the frictional force was obtained when the amount of the alkyl group-containing organic compound added was in the range of 0.8 to 4.9 parts by weight.

Example 4 A substrate 10 made of the same polycarbonate as that used in Example 1 was molded by an injection molding method, and subsequently, a first protective layer 11, a magneto-optical recording layer 12, and a second layer.
The protective layer 13 and the reflective film 14 were formed in the same manner as in Example 1 by using the sputtering method. Next, an ultraviolet curable resin containing 4 parts by weight of a fatty acid alkylsuccinic acid diester and the same as in Example 3 was applied to a portion near the center of the surface on which the reflective film 14 was formed, on a substantially concentric circle. Installed by drops and then relatively fast speed (2000 rpm-500 rpm)
The surface to be coated was rotated by 0 rotation) to spread the ultraviolet curable coating material on the entire surface to be coated, and the ultraviolet curable coating material was applied on the reflective film 14 by about 10 μm. Thereafter, the ultraviolet curable coating material on the reflective film 14 was irradiated with ultraviolet rays in the same manner as in Example 1 to form the protective coat 15.

FIG. 5 shows changes in the frictional force of the protective coat 15 with respect to the amount of ultraviolet light and the illuminance. The amount of ultraviolet light and the illuminance are the measurement results in the wavelength range of 330 nm to 370 nm, and the frictional force is that the modified polyamide is pressed against the protective coat 15 with a force of 10 mN, and the relative speed of the protective coat 15 and the modified polyamide is 1.2 m / s. Is the frictional force. The ultraviolet lamp used for irradiation is a high pressure mercury lamp. FIG.
As is clear from the figure, the illuminance of ultraviolet rays is 300 mW / cm ²
In the range of 1000 mW / cm ² or less, it is effective in reducing the frictional force, and the amount of ultraviolet light is 500 mJ / cm ² or more 1
It was effective in reducing the frictional force in the range of 500 mJ / cm ² or less.

In this embodiment, the first protective layer 11 containing SiN as a main component, the magneto-optical recording layer 12 containing TbFeCoCr as a main component, and the second protective layer containing SiN as a main component were formed on the substrate 10. 13 and the reflective film 14 containing AlTi as a main component were sequentially formed, but the present invention is not limited to this structure, and the effect of this embodiment can be realized as long as the film structure includes the magneto-optical recording layer 12.

Example 5 Using the same compound as in Example 1, (a) acrylic acid ester: 100 parts by weight (tetrahydrofurfuryl acrylate: 14 parts by weight, tricyclodecanyl acrylate: 54 parts by weight, neopentyl Glycol diacrylate: 32 parts by weight),
(B) Photopolymerizable prepolymer, (c) photopolymerization initiator, and (d) polymethylsiloxane were added in the amounts shown in Table 1 to prepare a coating composition, which was then spin-coated by the same method as in Example 1. Of the UV curable coating on the reflective film 14 using
Apply 0 μm and UV at room temperature (illuminance: 600 mW / cm
² , the amount of light: 800 mJ / cm ² ) to irradiate the protective coat 1
5 was formed.

The characteristics of the obtained magneto-optical disk are shown in Table 1.

[0087]

[Table 1]

As is apparent from Table 1, the magneto-optical disks of Experiment Nos. 2 to 5 and 8 to 11 of this example have excellent lubricity on the surface of the protective coat and excellent sliding characteristics even in a hot and humid environment. I was able to secure long-term reliability.

[0089]

As described above, according to the ultraviolet curable coating material of the present invention, a photopolymerization initiator, a photopolymerizable prepolymer, a monofunctional or difunctional (meth) acrylic acid ester and an organically modified polysiloxane, If necessary, a fatty acid ester, and further, by containing an organic compound having a side chain of a saturated or unsaturated fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end, excellent lubricity of the surface of the protective coat, Magneto-optical with excellent sliding characteristics even in high temperature and high humidity environment, long-term reliability can be ensured, adhesion of protective coat to reflective film is good, and sliding force is reduced with reduced frictional force. A disc can be realized.

Further, according to the manufacturing method of applying and curing the ultraviolet-curable coating material of the present invention, it is not necessary to add new manufacturing equipment to the conventional manufacturing equipment, and a high-quality magneto-optical disk can be obtained without increasing the equipment cost. It can be offered at a low price.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of a magneto-optical disk according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the organically modified polysiloxane composition of the protective coat of one example of the present invention and the frictional force.

FIG. 3 is a graph showing the relationship between the fatty acid ester composition and the frictional force of the protective coat of one example of the present invention.

FIG. 4 is a graph showing the relationship between the alkyl group-containing organic compound composition and the frictional force of the protective coat of one example of the present invention.

FIG. 5 is a graph showing changes in the frictional force with respect to the amount of ultraviolet light and the illuminance of the protective coat according to the embodiment of the present invention.

[Explanation of symbols]

 10 substrate 11 first protective layer 12 magneto-optical recording layer 13 first protective layer 14 reflective film 15 protective coat

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G11B 11/10 521 9075-5D G11B 11/10 521E 541 9075-5D 541F

Claims (31)

[Claims] 1. A UV-curable coating composition containing a (meth) acrylic acid ester, a photopolymerizable prepolymer, a photopolymerization initiator and an organic polysiloxane, wherein the composition ratio of each component is (a) (meth) acrylic. Acid ester 100 parts by weight (b) Photopolymerizable prepolymer 30 to 80 parts by weight (c) Photopolymerization initiator 10 to 40 parts by weight (d) Organic polysiloxane 0.1 to 10 parts by weight An ultraviolet curable coating composition for producing a magneto-optical disk. 2. The ultraviolet curable coating composition according to claim 1, wherein the fatty acid ester is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester. 3. An organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end with respect to 100 parts by weight of a (meth) acrylic acid ester.
The ultraviolet-curable coating composition according to claim 2, containing 10 to 10 parts by weight. 4. The ultraviolet curable coating composition according to claim 1, wherein the photopolymerizable prepolymer is at least one selected from urethane (meth) acrylate and epoxy (meth) acrylate. 5. The (meth) acrylic acid ester is lauryl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, tricyclodeca. The ultraviolet curable coating material according to claim 1, which is at least one selected from nyl (meth) acrylate, triethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and hexanediol di (meth) acrylate. Composition. 6. The ultraviolet-curable coating composition according to claim 2, wherein the aliphatic alkyl group contained in the fatty acid ester has a carbon number of 10 or more and 18 or less. 7. An organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end,
The ultraviolet-curable coating composition according to claim 3, which is a fatty acid alkyl succinic acid diester. 8. The ultraviolet-curable coating composition according to claim 1, wherein the (meth) acrylic acid ester is an acrylic acid ester or a methacrylic acid ester. 9. The ultraviolet curable coating composition according to claim 1, which has a viscosity at 25 ° C. of 20 to 100 centipoise. 10. The ultraviolet curable coating composition according to claim 1, wherein the organic polysiloxane is represented by the following formula (Formula 1). Embedded image 11. An inorganic compound is provided on an optically transparent substrate.
Forming a magneto-optical recording layer composed of a thin film of
Light to form a protective coating layer consisting of an organic compound on top of the layer
In the method for producing a magnetic disk, (a) (meth) acrylic acid ester 100 parts by weight (b) photopolymerizable prepolymer 30 to 80 parts by weight (c) photopolymerization initiator 10 to 40 parts by weight (d) organopolysiloxane An ultraviolet curable coating composition having a composition of 0.1 to 10 parts by weight is applied to the thin film,
Illuminance is 300 mW / cm ^Two1000 mW / cm or more^TwoLess than
In the lower range, the light intensity is 500 mJ / cm^TwoMore than 150
0mJ / cm^TwoThe ultraviolet rays in the range below are
Irradiate the chemical paint to cure the paint and form a protective coat layer
A method for manufacturing a magneto-optical disk, comprising: 12. The method for manufacturing a magneto-optical disk according to claim 11, wherein the ultraviolet-curable coating material is applied to a thin film of an inorganic compound to a thickness in the range of 5 to 50 μm. 13. The method of manufacturing a magneto-optical disk according to claim 11, wherein the fatty acid ester is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester. 14. An organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end with respect to 100 parts by weight of a (meth) acrylic acid ester.
The method of manufacturing a magneto-optical disk according to claim 11, including 1 to 10 parts by weight. 15. The method for producing a magneto-optical disk according to claim 11, wherein the photopolymerizable prepolymer is at least one selected from urethane (meth) acrylate and epoxy (meth) acrylate. 16. The (meth) acrylic acid ester is lauryl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth).
Acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, triethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and hexanediol di (meth) acrylate The method of manufacturing a magneto-optical disk according to claim 11, which is at least one selected from acrylates. 17. The aliphatic alkyl group of the fatty acid ester has a carbon number of 10 or more and 18 or less.
1. The method for manufacturing a magneto-optical disk according to 1. 18. The organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end is a fatty acid alkyl succinic acid diester.
1. The method for manufacturing a magneto-optical disk according to 1. 19. The method for producing a magneto-optical disk according to claim 11, wherein the (meth) acrylic acid ester is an acrylic acid ester or a methacrylic acid ester. 20. The viscosity at 25 ° C. is 20-100.
The method of manufacturing a magneto-optical disk according to claim 11, wherein the method is centipoise. 21. The method of manufacturing a magneto-optical disk according to claim 11, wherein the organic polysiloxane has the formula (Formula 1). 22. A magneto-optical disk comprising a magneto-optical recording layer made of a thin film of an inorganic compound formed on an optically transparent substrate, and a protective coating layer made of an organic compound formed on the magneto-optical recording layer. The organic compound is (a) (meth) acrylic acid ester 100 parts by weight (b) photopolymerizable prepolymer 30 to 80 parts by weight (c) photopolymerization initiator 10 to 40 parts by weight (d) organically modified polysiloxane 0 A magneto-optical disk, which is a cured product of an ultraviolet curable coating composition having a composition of 1 to 10 parts by weight. 23. A magneto-optical disk, wherein the protective coat composed of the organic compound has a thickness in the range of 5 to 50 μm. 24. The magneto-optical disk according to claim 22, which contains 0.1 to 10 parts by weight of a fatty acid ester with respect to 100 parts by weight of a (meth) acrylic acid ester. 25. An organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end with respect to 100 parts by weight of a (meth) acrylic acid ester.
23. The magneto-optical disk according to claim 22, including 1 to 10 parts by weight. 26. The magneto-optical disk according to claim 22, wherein the photopolymerizable prepolymer is at least one selected from urethane (meth) acrylate and epoxy (meth) acrylate. 27. The (meth) acrylic acid ester is lauryl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth).
Acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, triethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and hexanediol di (meth) acrylate The magneto-optical disk according to claim 22, which is at least one selected from acrylates. 28. The aliphatic alkyl group of the fatty acid ester has a carbon number of 10 or more and 18 or less.
4. The magneto-optical disk according to item 4. 29. The organic compound having a side chain of a fluoroalkyl group or an unsaturated aliphatic alkyl group at the molecular end is a fatty acid alkyl succinic acid diester.
5. The magneto-optical disk according to item 5. 30. The magneto-optical disk according to claim 22, wherein the (meth) acrylic acid ester is an acrylic acid ester or a methacrylic acid ester. 31. The organic polysiloxane has the formula (Formula 1)
23. The magneto-optical disk according to claim 22, which is represented by