JPH05114164A - Information recording disk and production thereof - Google Patents

Abstract

PURPOSE:To obtain the disk having excellent transparency, low double refractiveness, water absorptivity, and heat resistance by using a substrate consisting of specific polyimide fluoride and providing pregrooves for tracking on one surface thereof, thereby forming a recording layer. CONSTITUTION:The substrate 7 is formed of the polyimide fluoride consisting of the polyimide having the repeating unit expressed by formula as a main constituting element. In the formula, R1 and R2 consist of 1 to 3 pieces of benzene rings which are indirectly bonded at R1 and directly or indirectly at R2. The hydrogen in this polyimide is fully substd. with the fluorine or perfluoroalkyl group. A recording layer 8 provided with the pregrooves and a protective layer 9 are formed on one surface of such substrate 7, by which the information recording disk 10 is constituted. The disk having the excellent preservable stability and mass productivity is obtd. by this constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording excellent in transparency, birefringence, low water absorption, heat resistance, surface accuracy and plane accuracy used for image files, document files and file memories in computer systems. The present invention relates to a disc and a method for manufacturing the disc.

[0002]

2. Description of the Related Art An optical disk storage system capable of writing and reading information by light and a magneto-optical disk storage system capable of writing and reading information by light and magnetism are used as a small-sized and large-capacity storage device having a high areal recording density. It has shown rapid development in recent years. These storage systems have characteristics such as large capacity, non-contact recording / reproduction, high-speed random access, and long life. For example, a typical example of the optical disk storage system is a thin film of an information recording medium on a transparent substrate. After forming a protective layer on this information recording medium, several μm from the transparent substrate side.
Information is written and read by irradiating a laser beam with a diameter of m. Here, the transparent substrate has transparency at a used wavelength, low birefringence, low water absorption, heat resistance, high plane accuracy, and high surface accuracy, and also has excellent moldability, mass productivity, and handleability. Etc. are required to be satisfied. Conventionally, glass and plastic have been studied as substrate materials, but since glass is an inherently brittle material, it has the practical drawback of being easily broken. Currently, plastic materials such as acrylic and polycarbonate are used. Substrate consisting of is mainly used for practical use.

[0003]

When acryl is used as a substrate constituting an information recording disk, acryl is excellent in transparency, birefringence, and moldability, but it is a brittle material and therefore rotates at high speed. At times, it has a drawback that it is easily broken, and its water absorption is large, so that it is likely to undergo warp modification.
Polycarbonate can withstand use in terms of strength, but when a substrate is formed by injection molding that takes mass productivity into consideration, polycarbonate has a large photoelastic constant and thus birefringence increases due to molding strain.・
There is a big problem that the molding conditions must be precisely controlled to eliminate the read error. In order to solve this problem, even when a substrate is molded by a casting method that does not cause molding distortion, it is difficult to obtain a highly transparent substrate because the polycarbonate easily crystallizes in the presence of a solvent. The information recording medium is usually formed on the surface of the substrate by a method such as vapor deposition and sputtering. In this case as well, a considerable amount of heat is added to the substrate, and the substrate using the ordinary plastic material is used. However, since it lacks heat resistance, it has a drawback that the substrate is likely to be thermally deformed. On the other hand, on the substrate surface of the information recording disk,
Although it is necessary to form a pre-groove for tracking, formation of this pre-groove also has a serious problem in terms of substrate material and manufacturing restrictions. The present invention is
In light of the above problems, an information recording disk which is excellent in transparency, birefringence, water absorption, heat resistance, surface accuracy, flatness accuracy, molding workability, mass productivity, and handling, and in which a tracking pregroove can be easily formed. And a method for manufacturing the same.

[0004]

The present invention will be described in brief. The first invention of the present invention relates to an information recording disk and is represented by the following general formula (Formula 1):

[Chemical 1] [Wherein R ₁ is the following formula (Formula 2):

[Chemical 2] R ₂ is a group represented by the following formula (Formula 3):

[Chemical 3] Wherein Rf is fluorine or a perfluoroalkyl group, and X is the following formula (Formula 4):

[Chemical 4] (Wherein Rf ′ is a perfluoroalkylene group and n is a group of 1 to 10) and a polyimide containing a repeating unit represented by A substrate made of fluorinated polyimide as a component, a tracking pre-groove formed on one surface of the substrate, and an information recording layer provided on the pre-groove formation surface of the pre-grooved substrate, To do. A second invention of the present invention relates to another information recording disk, characterized in that an optically transparent protective layer is provided so as to cover the information recording layer in the first invention. A third invention of the present invention relates to the method for manufacturing the information recording disk of the first invention, which is represented by the following general formula (Formula 5):

[Chemical 5] Tetracarboxylic acids represented by [wherein R ₁ is the general formula (Formula 1) in the same meaning as R _1], or an acid component mainly composed of a derivative represented by the following general formula (Formula 6):

Embedded image H ₂ N-R ₂ -NH _2-diamine was reacted with a diamine component mainly comprising represented by [wherein R ₂ is Formula 1 in the same meaning as R ₂ in] , The following general formula (Formula 7):

[Chemical 7] [R ₁ and R ₂ wherein R ₁ and R ₂ are the general formula (Formula 1)
Synonymous with] a step of producing a fluorinated polyamic acid having a polyamic acid containing a repeating unit as a main constituent, the fluorinated polyamic acid is imidized by a casting method using a pre-grooved master for tracking. And a pregroove-containing fluorinated polyimide substrate, and a step of forming an information recording layer on the pregroove-forming surface of the pregroove-containing fluorinated polyimide substrate. Furthermore, a fourth invention of the present invention relates to another method of manufacturing an information recording disk, wherein in the manufacturing method of the third invention, an optically transparent protective layer is further provided so as to cover the information recording layer. It is characterized by having a step of forming.

In order to achieve the above-mentioned object, the inventors of the present invention have made various studies on the transparent substrate, and as a result, as a result, fluorinated polyimide has a high transparency, low birefringence, low water absorption,
It was found to have heat resistance.

In the present invention, the fluorinated polyimide used as the substrate material is one in which part or all of the monovalent element bonded to carbon such as the alkyl group of polyamic acid and the phenyl ring is fluorine or perfluoroalkyl group. is there.

The information recording layer is not limited to recording systems such as thermal recording and thermomagnetic recording, but includes information recording layers for all recording systems. It is applicable to all recording methods.

Further, in the present invention, a transparent protective layer is provided on the upper surface of the information recording layer as necessary, but the transparent protective layer is not always necessary, and a transparent cover is provided on the upper surface of the information recording layer in a non-contact manner. It may have a disk configuration and is not particularly limited.

The inventors of the present invention measured the absorption spectra of various existing polyimides and polyimide optical materials in the infrared region and near infrared region, calculated the optical loss in the near infrared region, and earnestly studied the cause. investigated. As a result, the first cause of large optical loss in the near infrared region is
It has been clarified that it is the harmonic absorption of the stretching vibration of the C—H bond in the alkyl group, the phenyl ring, etc. and the absorption of the harmonic vibration of the stretching vibration of the C—H bond and the combined sound of the bending vibration.

In the fluorinated polyimide of the present invention, part or all of the monovalent element bonded to carbon such as an alkyl group or a phenyl ring is a fluorine or perfluoroalkyl group, and a C-H bond is preferably contained in the repeating unit. The structure that does not allow C is the largest cause of light loss in the near infrared region.
By eliminating vibration absorption due to —H bond and introducing an imide bond into the main chain structure to form a polyimide, heat resistance (260 ° C.) sufficient for producing an optoelectronic integrated circuit is obtained.
Or more).

The tetracarboxylic acid or its derivative used for producing the fluorinated polyimide of the present invention is
Bond to carbon such as alkyl group and phenyl ring in the molecule 1
Any valent element may be used, provided that part or all of the valent element is a fluorine or perfluoroalkyl group. Examples of acid anhydrides, acid chlorides, ester compounds and the like as tetracarboxylic acids and their derivatives include the following. Examples of the tetracarboxylic acid are 1,4-difluoropyromellitic acid, 1-trifluoromethyl-4-fluoropyromellitic acid, 1,4-di (trifluoromethyl) pyromellitic acid, and 1,4. -Di (pentafluoroethyl) pyromellitic acid, hexafluoro-3,3 ', 4,4'-biphenyltetracarboxylic acid, hexafluoro-3,3', 4,4'-benzophenonetetracarboxylic acid, 2,2 -Bis (3,4-dicarboxytrifluorophenyl) hexafluoropropane, 1,3-bis (3,4-dicarboxytrifluorophenyl) hexafluoropropane, 1,4-bis (3,4-dicarboxytri) Fluorophenoxy) tetrafluorobenzene, hexafluoro-3,3 ′ (or 4,4 ′)-oxybisphthalic acid, etc. It is below. Among them, fluorinated dianhydrides having a fluoroalkyl group introduced into the benzene ring of pyromellitic dianhydride, 1,4-
Di (trifluoromethyl) pyromellitic dianhydride,
A method for producing 1,4-di (pentafluoroethyl) pyromellitic dianhydride and the like is described in Japanese Patent Application No. 63-165056.

Further, examples of the diamine which can be used in the present invention include an alkyl group excluding an amino group in the molecule, a part or all of a monovalent element bonded to carbon such as a phenyl ring, or fluorine or perfluoroalkyl. Any group may be used as long as it is based on 3,4,5,6-tetrafluoro-1,2-phenylenediamine, 2,4,5,6
-Tetrafluoro-1,3-phenylenediamine, 2,
3,5,6-tetrafluoro-1,4-phenylenediamine, 4,4'-diaminooctafluorobiphenyl,
Bis (2,3,5,6-tetrafluoro-4-aminophenyl) ether, bis (2,3,5,6-tetrafluoro-4-aminophenyl) sulfone, hexafluoro-2,2'-bis ( Trifluoromethyl) -4,4'-
Diaminobiphenyl and the like can be mentioned.

The method for producing the fluorinated polyamic acid, which is the fluorinated polyimide precursor used in the present invention, may be the same as the production conditions for ordinary polyamic acid, and generally, N-methyl-2-pyrrolidone, N, The reaction is carried out in a polar organic solvent such as N-dimethylacetamide or N, N-dimethylformamide. In the present invention, not only a diamine or a tetracarboxylic acid component is used as a single compound, but a plurality of diamine and tetracarboxylic acid components may be mixed and used. In that case, the total number of moles of the plural or single diamine components and the total number of moles of the plural or single tetracarboxylic acid components are equal or nearly equal. In the polymerization solution of the polyamic acid or the like, the concentration of the solution is 5 to 40% by weight (preferably 10 to 25% by weight), and the rotational viscosity (25 ° C.) of the polymer solution is 50 to 5000 poise. Is preferred.

The master disc with pregrooves for tracking used in the present invention can be easily obtained by a conventional process for producing a master disc for an information recording layer disc exemplified in Japanese Patent Application No. 59-20732. Further, in the present invention, the fluorinated polyimide substrate is molded by using the casting method, but it is not necessarily limited to molding by the casting method, and if high plane accuracy and surface accuracy can be obtained, ordinary polyimide is used. Molding may be performed by using a casting method which is the molding method of.

As described above, when an information recording layer disk using the pregrooved substrate made of the above fluorinated polyimide resin is manufactured by a casting method, it has a high transparency, a low water absorption characteristic of the fluorinated polyimide resin, In addition to low birefringence and high heat resistance, it is possible to obtain an information recording disk excellent in surface accuracy and plane accuracy.

[0016]

The above fluorinated polyimide resin is transparent in the near infrared region, has low birefringence (main refractive index difference of 1 × 10 ⁻³ or less), low water absorption (saturated water absorption of 0.2% or less), and heat resistance. It has properties and is extremely suitable as a substrate material for information recording disks. Further, since the fluorinated polyimide resin of the present invention can be easily made into a substrate by casting fluorinated polyamic acid, if a master with a pre-groove is used as a cast mold, the pre-groove with excellent surface accuracy and flatness can be obtained. The attached substrate can be easily obtained. Further, since the fluorinated polyimide resin has heat resistance, the substrate is not deformed when the information recording medium is formed on the substrate surface by vapor deposition, sputtering or the like.

[0017]

EXAMPLES The information recording disk of the present invention will be described in detail below with reference to specific examples. Although the examples of the present invention exemplify the information recording disk using the perfluorinated polyimide resin, the present invention is not limited to this, and an information recording disk using a partially fluorinated polyimide resin may be used. .. In the following examples, imidation was confirmed by characteristic absorption due to symmetric and asymmetric stretching vibration of carbonyl group in infrared absorption spectrum, and light transmittance was measured by measuring ultraviolet-visible absorption spectrum.

Example 1 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride having the following structural formula (Formula 8) in an Erlenmeyer flask:

[Chemical 8] 11.644 g (20.0 mmol) and 2,4,5,6-tetrafluoro-1, represented by the following structural formula (Formula 9)
3-Phenylenediamine:

[Chemical 9] 3.602 g (20.0 mmol) and 86 g of N, N-dimethylacetamide (DMAc) were added. This solution was stirred at room temperature for 3 days in a nitrogen atmosphere to obtain a DMAc solution of polyamic acid. This solution was enclosed in a cast mold having a cavity thickness of 1.2 mm equipped with a master mold with pre-groove as shown in FIG.
Fluorinated polyimide substrate with pre-groove having a thickness of 1.2 mm by imidizing under conditions of 60 ° C. for 1 hour, 250 ° C. for 30 minutes, 350 ° C. for 1 hour, and releasing the solidified substrate from the casting mold. Got That is, FIG. 1 is a process diagram illustrating the cast molding method. In FIG. 1, reference numeral 1 is a mold type, 2 is a master type with a pre-groove, 3 is a gasket, 4 is a fluorinated polyamic acid, 5 is a fastening jig, 6 is a pre-groove, and 7 is a fluorinated polyimide substrate with a pre-groove. means.

When the infrared absorption spectrum of this polyimide substrate was measured, the absorption peculiar to the imide group appeared at 1790 cm ^-1, and it was confirmed that the imidization proceeded completely. When the light absorption of this polyimide substrate was measured in the wavelength range of 0.8 to 1.7 μm, no light absorption other than water absorption was observed as shown in FIG. Further, it was smaller than the conventional polyimide film produced in Comparative Example 1 shown below. That is, in FIG. 2, the solid line is a graph showing the wavelength dependence of the light absorbance of the perfluorinated polyimide of Example 1, and the broken line is the polyimide of Comparative Example 1. In FIG. 2, the vertical axis represents absorbance and the horizontal axis represents wavelength (μ
m).

The fluorinated polyimide substrate with pregroove thus produced was 130 mmφ in outer diameter and 15 mmφ in inner diameter.
After processing into the shape of, the pregroove forming surface of the substrate,
For example, a CS ₂ -Te plasma polymerized film that can be changed by light energy was applied as a recording layer to a thickness of 300A. Further, a transparent protective layer made of silicon oxide and having a thickness of 10 μm was provided on the recording layer by sputtering to manufacture an information recording disc as shown in FIG. That is, FIG.
It is a figure which illustrates the structure of the information recording disc which used fluorinated polyimide as a board | substrate. In FIG. 3, reference numeral 7 has the same meaning as in FIG. 1, 8 is an information recording layer, 9 is a protective layer, and 10 is a protective layer.
Means an information recording disk. This information recording disk 10 is installed on the turntable of the disk drive device and recorded at an output of 4 mW while rotating at 1800 rpm,
When reproduced with an output of 3 mW, good recording / reproducing characteristics could be obtained.

EXAMPLE 2 In an Erlenmeyer flask, 11.644 g (20.0 mmol) of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride and the following structural formula (Formula 10) Bis (2,3,5,6-tetrafluoro-4-aminophenyl) ether:

[Chemical 10] 6.883 g (20.0 mmol), and DMAc 105 g
Then, a fluorinated polyimide substrate with a pre-groove was molded in the same manner as in Example 1 below. When the absorption spectrum of this substrate was measured, no absorption peak other than water absorption was found in the wavelength range of 0.8 to 1.7 μm.
Moreover, it was smaller than the conventional polyimide film produced in Comparative Example 1. Then, a recording layer and a protective layer were formed on the pregroove forming surface of the fluorinated polyimide substrate with pregroove to obtain an information recording disk. The information recording disc manufactured in this manner showed good recording and reproducing characteristics as in Example 1.

Example 3 In an Erlenmeyer flask, 11.44 g (20.0 mmol) of 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride and the following structural formula (Formula 11) are shown. Bis (2,3,5,6-tetrafluoro-4-aminophenyl) sulfide:

[Chemical 11] 7.205 g (20.0 mmol), and DMAc 107 g
Then, a fluorinated polyimide substrate with a pre-groove was molded in the same manner as in Example 1 below. When the absorption spectrum of this substrate was measured, no absorption peak other than water absorption was found in the wavelength range of 0.8 to 1.7 μm.
Moreover, it was smaller than the conventional polyimide film produced in Comparative Example 1. Then, a recording layer and a protective layer were formed on the pregroove forming surface of the fluorinated polyimide substrate with pregroove to obtain an information recording disk. The information recording disc manufactured in this manner showed good recording and reproducing characteristics as in Example 1.

Example 4 An Erlenmeyer flask having 1,4-having the following structural formula (Formula 12)
Difluoropyromellitic dianhydride:

[Chemical 12] 5.082 g (20.0 mmol) and 2,4,5,6-tetrafluoro-1,3-phenylenediamine 3.602 g
(20.0 mmol) and 49 g of DMAc were added, and a fluorinated polyimide substrate with pregroove was molded in the same manner as in Example 1 below. When the absorption spectrum of this substrate was measured, no absorption peak other than water absorption was found in the wavelength range of 0.8 to 1.7 μm. Comparative Example 1
It was smaller than the conventional polyimide film prepared in. Then, a recording layer and a protective layer were formed on the pregroove forming surface of the fluorinated polyimide substrate with pregroove to obtain an information recording disk. The information recording disc manufactured in this manner showed good recording and reproducing characteristics as in Example 1.

Example 5 5.082 g (20.0 mmol) of 1,4-difluoropyromellitic dianhydride and bis (2,3,3) were added to an Erlenmeyer flask.
5,6-Tetrafluoro-4-aminophenyl) ether 6.883 g (20.0 mmol), and DMAc 68 g
Then, a fluorinated polyimide substrate with a pre-groove was formed in the same manner as in Example 1 below. When the absorption spectrum of this substrate was measured, no absorption peak other than water absorption was found in the wavelength range of 0.8 to 1.7 μm. Moreover, it was smaller than the conventional polyimide film produced in Comparative Example 1. Then, a recording layer and a protective layer were formed on the pregroove forming surface of the fluorinated polyimide substrate with pregroove to obtain an information recording disk. The information recording disc manufactured in this manner showed good recording and reproducing characteristics as in Example 1.

Example 6 In an Erlenmeyer flask, 5.082 g (20.0 mmol) of 1,4-difluoropyromellitic dianhydride and bis (2,3,3)
7.205 g (20.0 mmol) of 5,6-tetrafluoro-4-aminophenyl) sulfide and DMAc70
g was added, and a fluorinated polyimide substrate with pregroove was formed in the same manner as in Example 1 below. When the absorption spectrum of this substrate was measured, the wavelength was 0.8 to 1.7 μm.
No absorption peak was observed other than the absorption of water in the range. Moreover, it was smaller than the conventional polyimide film produced in Comparative Example 1. Then, a recording layer and a protective layer were formed on the pregroove forming surface of the fluorinated polyimide substrate with pregroove to obtain an information recording disk. The information recording disc manufactured in this manner showed good recording and reproducing characteristics as in Example 1.

Comparative Example 1 In an Erlenmeyer flask, 2,2 having the following structural formula (Formula 13)
-Bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride:

[Chemical 13] 8.885 g (20.0 mmol) and the following structural formula
2,2'-bis (trifluoromethyl) represented by 4)
-4,4'-Diaminobiphenyl:

[Chemical 14] 6.405 g (20.0 mmol) and 87 g of DMAc were added, and a fluorinated polyimide substrate with pregroove was molded in the same manner as in Example 1 below. When the absorption of light in the wavelength range of 0.8 to 1.7 μm of this polyimide film was measured, as shown by the broken line in FIG. 2, the absorption due to the third harmonic of the stretching vibration of the C—H bond was found around 1.1 μm. , 1.
Absorption by harmonics of stretching vibration of C—H bond and bending sound of combined vibration near 4 μm, and C near 1.65 μm.
Absorption by the second harmonic of the stretching vibration of the -H bond appeared. From these results, it became clear that the perfluorinated polyimide of the present invention has an extremely small light transmission loss rate in the near infrared region as compared with the conventional one. Then, on the pre-groove formation surface of the fluorinated polyimide substrate with the pre-groove,
An information recording disk was obtained by forming a recording layer and a protective layer.
The recording / reproducing characteristics of the information recording disc manufactured in this manner were extremely poor.

[0027]

As described above, according to the information recording disk of the present invention using the fluorinated polyimide substrate as the substrate material, the fluorinated polyimide is extremely excellent in transparency, birefringence, water absorption and heat resistance. Therefore, the fluorinated polyamic acid as a substrate material, by a casting method using a pre-grooved master mold, it is possible to easily obtain a pre-grooved fluorinated polyimide substrate having excellent surface accuracy and plane accuracy, the As a result, the information recording disc in which the information recording layer and the protective layer, if necessary, were formed on the pre-groove forming surface of the substrate showed extremely good recording and reproducing characteristics as compared with the conventional information recording disc.

[Brief description of drawings]

FIG. 1 is a process diagram illustrating a cast molding method.

2 is a graph showing the wavelength dependence of light absorbance in the perfluorinated polyimide of Example 1 and in the polyimide of Comparative Example 1, respectively.

FIG. 3 is a diagram illustrating a configuration of an information recording disk using fluorinated polyimide as a substrate.

[Explanation of symbols]

1 ... Mold type, 2 ... Master type with pre-groove, 3
... Gasket, 4 ... Fluorinated polyamic acid, 5 ...
Tightening jig, 6 ... Pre-groove, 7 ... Fluorinated polyimide substrate with pre-groove, 8 ... Information recording layer,
9 ... Protective layer, 10 ... Information recording disk

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[Procedure amendment]

[Submission date] October 8, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shigekuni Sasaki 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (4)

[Claims] 1. The following general formula (Formula 1): [Wherein R ₁ is the following formula (Formula 2): R ₂ is a group represented by the following formula (Formula 3): Wherein Rf is fluorine or a perfluoroalkyl group, and X is the following formula (Formula 4): (Wherein Rf ′ is a perfluoroalkylene group and n is a group of 1 to 10) and a polyimide containing a repeating unit represented by A substrate made of fluorinated polyimide as a component, a tracking pre-groove formed on one surface of the substrate, and an information recording layer provided on the pre-groove formation surface of the pre-grooved substrate, An information recording disc. 2. An information recording disk comprising an optically transparent protective layer so as to cover the information recording layer according to claim 1. 3. The following general formula (Formula 5): Tetracarboxylic acids represented by [wherein R ₁ is the general formula (Formula 1) in the same meaning as R _1], or an acid component mainly composed of a derivative represented by the following general formula (Formula 6): [ of 6] H ₂ N-R ₂ -NH ₂ the diamine represented by [wherein R ₂ is the general formula (formula 1) R ₂ as synonymous in] by reacting a diamine component composed mainly, The following general formula (Formula 7): [R ₁ and R ₂ wherein R ₁ and R ₂ are the general formula (Formula 1)
Synonymous with] a step of producing a fluorinated polyamic acid having a polyamic acid containing a repeating unit as a main constituent, the fluorinated polyamic acid is imidized by a casting method using a pre-grooved master for tracking. Of the pre-grooved fluorinated polyimide substrate, the step of forming an information recording layer on the pre-groove formation surface of the pre-grooved fluorinated polyimide substrate, an information recording disk characterized by the following steps: Production method. 4. A method for manufacturing an information recording disk, comprising the step of forming an optically transparent protective layer so as to cover the information recording layer according to claim 3.