JPH09198710A - Optical disk and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk which can sufficiently cope with high-degree densification and is superior in durability against a high temperature and high humidity. SOLUTION: This type of optical disk is produced by forming uneven pits on a transparent substrate which is 30 to 300μm in thickness and composed of thermoplastic norborne resin, a functional film on said uneven pit surface and laminating a protective layer on the said film. And, the optical disk is produced by coating UV-hardenable resin on the film, bringing a stamper having uneven pits in pressure-contact with the resin coating and then hardening the resin by applying UV rays or forming uneven pits on the substrate to form an active film by heat-pressing a stamper directly on a transparent substrate composed of thermoplastic norbornane-based resin and then forming a protective film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk, and more particularly to an optical disk obtained by forming concave and convex pits on a sheet, laminating a recording film, a reflective film, etc., and then punching it into a disk shape.

[0002]

2. Description of the Related Art Conventionally, there is known a method of manufacturing a disc by forming a recording layer on a transparent film and then punching the disc into a disc shape. For example, in the photopolymer method (2P method), an ultraviolet curable resin is filled or applied between a stamper (mold) having concave and convex pits in which predetermined information is stored and a transparent substrate serving as a disk base material. After irradiating ultraviolet rays to cure the resin, the stamper is peeled off to form a recording layer having concave and convex pits on a transparent substrate, and a metal reflection film is formed on the concave and convex pit surface by means such as metal deposition or sputtering. Is formed,
Further, a protective film is formed on top of it and punched out in the shape of a disk. However, the transparent substrate that has been conventionally used for the optical disc as described above has various problems caused by the resin used as the material thereof, and the disc is formed by punching after actually forming a recording pattern on these films. It was extremely difficult to obtain. For example, as a transparent substrate, a polycarbonate resin (P
C), triacetyl cellulose (TAC), polymethyl methacrylate resin (PMMA), polyimide resin (P
Films made of I), polyester resins such as polyethylene terephthalate resin (PET), and aromatic polyester resins such as polyarylate resin (PAR) are known, but PC has a photoelastic coefficient of about 9 × 10 ⁻¹² cm. ² / dyne
Therefore, there is a problem that the birefringence becomes too large, becomes non-uniform, and the birefringence changes due to a slight stress generated during assembly or environmental changes. At the time, or during processing such as stacking for imparting a function or film formation, scratches are likely to occur, and care must be taken in handling, resulting in poor productivity.
Since TAC and PMMA have poor heat resistance and water absorption, they are deformed by the heat applied by forming functions such as film formation of recording film and reflective film and pattern formation of thermosetting resin, and the surrounding moisture during handling. There is a case that the function is deteriorated due to warping of the substrate due to the absorption of the. PE
Since T is a crystalline polymer, birefringence easily occurs, heat resistance is insufficient, and adhesion to a functional film such as a recording film or a reflective film is poor. There was a problem of infiltration and deterioration of the film. Further, since PI is a thermosetting resin, the productivity is inferior because the degree of freedom in film forming is limited, and the obtained film is often colored and is unsuitable for optical disk applications. Similarly, since a film made of PAR is often colored and has insufficient transparency, it was unsuitable for optical disk applications where severe optical characteristics are required. Particularly in recent years, as optical discs have become higher in density, disc substrates are required to have strict optical characteristics, and heat resistance is required so that the optical characteristics do not change due to heat applied in the production process such as film formation. Therefore, it has been difficult to obtain such a disk substrate with a transparent film which has been widely used in the past.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has heat resistance, moldability, dimensional stability, and adhesion to a functional film such as a recording film or a reflective film. The present invention provides an optical disc having excellent optical characteristics, small birefringence, and excellent optical characteristics.

[0004]

DISCLOSURE OF THE INVENTION The present invention is an optical disk and a thermoplastic norbornene-based optical disk characterized by comprising a transparent substrate made of a thermoplastic norbornene-based resin, and a concavo-convex pit, a functional film and a protective film laminated on the transparent substrate. A UV-curable resin is applied on a transparent substrate made of resin, and a stamper having concave and convex pits is pressure-bonded, and then the resin is cured by UV rays, or the stamper is directly heat-pressed on the transparent substrate made of thermoplastic norbornene-based resin. By providing the uneven pits on the substrate by the above, a functional film is formed, and then a protective film is formed.

The thermoplastic norbornene resin used in the present invention has a norbornane skeleton in its repeating unit. For example, the thermoplastic resin contains a norbornane skeleton represented by the general formulas (I) to (IV).

[0006]

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[0007]

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[0008]

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[0009]

Embedded image (In the formula, A, B, C and D represent a hydrogen atom or a monovalent organic group.) Examples of the thermoplastic resin having a norbornane skeleton which can be used in the present invention include JP-A-60-1.
68708, JP-A-62-252406,
JP 62-252407 A, JP 2-1334
Resins described in JP-A No. 13, JP-A-63-145324, JP-A-63-264626, JP-A-1-240517, JP-B-57-8815 and the like can be mentioned. . Specific examples of the thermoplastic resin include metathesis polymerization of at least one tetracyclododecene derivative represented by the following general formula (V) or an unsaturated cyclic compound copolymerizable with the tetracyclododecene. A hydrogenated polymer obtained by hydrogenating the obtained polymer can be exemplified.

[0010]

Embedded image (In the formula, A to D are the same as above.) In the tetracyclododecene derivative represented by the general formula (V), it is preferable that A, B, C and D contain a polar group in order to improve heat resistance and heat resistance. It is preferable in terms of adhesion to the functional film. Further, the polar group - (CH _{2) n} COOR
³ (wherein R ³ is a hydrocarbon group having 1 to 20 carbon atoms, and n is an integer of 0 to 10), the hydrogenated polymer obtained has a high glass transition temperature. It is preferable that the compound has-(CH ₂ ) _n COOR.
^The group represented by ³ is preferably contained in one molecule per molecule of the tetracyclododecene derivative of the general formula (V). In the above general formula, R ¹ is a hydrocarbon group having 1 to 20 carbon atoms, which is preferable in that the hygroscopicity of the obtained hydrogenated polymer becomes smaller as the number of carbon atoms increases, but the hydrogenated polymer obtained is From the viewpoint of the balance with the glass transition temperature, a chain alkyl group having 1 to 4 carbon atoms or a (poly) cyclic alkyl group having 5 or more carbon atoms is preferable, and a methyl group, an ethyl group, and a cyclohexyl group are particularly preferable. Is preferred. Furthermore, - (CH ₂₎ carbon atom group is bonded, represented by _n COOR ^3, simultaneously tetracyclododecene of general formula (V) which is a hydrocarbon group having 1 to 10 carbon atoms which is bonded as a substituent Derivatives are preferred because they reduce hygroscopicity. In particular, the tetracyclododecene derivative of the general formula (V) in which the substituent is a methyl group or an ethyl group is preferable in that the synthesis is easy. Specifically, 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.
1 ^2,5 1 ^7,10 ] dodeca-8-ene is preferred.

These tetracyclododecene derivatives or a mixture of unsaturated cyclic compounds copolymerizable therewith are disclosed, for example, in JP-A-4-77520, page 4, upper right column, line 12 to page 6, lower right column, The thermoplastic resin used in the present invention can be prepared by metathesis polymerization and hydrogenation by the method described in line 6. Further, the glass transition temperature (Tg) of the hydrogenated polymer is preferably in the range of 100 ° C to 250 ° C, particularly preferably in the range of 120 to 200 ° C. When the temperature is lower than 100 ° C., the heat resistance of a molded article made of the resin composition is poor. In addition, Tg is 250
If the temperature is higher than 0 ° C, the molding temperature becomes high and the resin is burned and colored, so that it becomes difficult to obtain a high-quality molded product. The hydrogenation rate of the hydrogenated polymer is 60 MHz, ¹ H-N
The value measured by MR is 50% or more, preferably 90% or more, more preferably 98% or more. The higher the hydrogenation rate, the better the stability to heat and light.

In the present invention, the hydrogenated polymer used as the thermoplastic resin having a norbornane skeleton is
The gel content in the hydrogenated polymer is preferably 5% by weight or less, more preferably 1% by weight. In the present invention, the thermoplastic norbornene-based resin used as the material of the transparent substrate may be, if necessary, a known antioxidant such as 2,6 as long as the effect of the present invention is not impaired.
-Di-t-butyl-4-methylphenol, 2,2'-
Dioxy-3,3'-di-t-butyl-5,5'-dimethylphenylmethane, tetrakis [methylene-3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di- t-butyl-4-hydroxybenzyl-
Benzene, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2 ′
-Dioxy-3,3'-di-t-butyl-5,5'-diethylphenylmethane, 3,9-bis [1,1-dimethyl-2- [β- (3-t-butyl-4-hydroxy -5
-Methylphenyl) propionyloxy] ethyl],
2,4,8,10-Tetraoxpyro [5,5] undecane, tris (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-t-) Butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-
t-butyl-4-methylphenyl) phosphite, 2,
2-methylenebis (4,6-di-t-butylphenyl)
Octyl phosphite can be added.

In addition to the above-mentioned antioxidant, the above-mentioned thermoplastic norbornene-based resin may optionally contain an ultraviolet absorber such as pt-butylphenyl salicylase.
2,2'-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2- (2'-dihydroxy-4'-m-octoxyphenyl) benzotriazole; Stabilizers, antistatic agents, flame retardants, impact resistance improving elastomers and the like can be added. Also,
Additives such as lubricants may be added for the purpose of improving workability. In the present invention, the above-mentioned thermoplastic norbornene-based resin can be used as the transparent substrate of the optical disk of the present invention by a known sheet or film forming method such as extrusion molding or solution casting. In this case, the thickness of the transparent substrate is 30 to 300 μm, preferably 70 to 200 μm.

To manufacture an optical disk using the transparent substrate, first, uneven pits are formed on the transparent substrate. The concave and convex pits are formed by applying an ultraviolet curable resin or a thermosetting resin on a transparent substrate, then pressing a stamper having concave and convex pits in which predetermined information is stored, and then curing the resin by ultraviolet rays or heat, or A method of forming uneven pits on the substrate by directly hot pressing a stamper on the transparent substrate can be mentioned. The ultraviolet curable resin may be a known acrylic resin, and the thermosetting resin may be a phenol resin or an epoxy resin. Next, a reflective film, a recording film,
A functional film such as a dielectric film is formed. The functional film may be an inorganic compound or an organic compound. Inorganic compounds that can be used as a functional film include Ni, Al, A in the reflective film.
u, Pt and other metals with high reflectance, Tb-F for recording film
e-based alloy, Dy-Fe-based alloy, Cd-Tb-based alloy, Cd
-Tb-Dy-Fe based alloy, Cd-Co based alloy, Tb-
In addition to rare earth-transition metal amorphous alloys such as Fe-Co based alloys, Ge-Te based, Sb-Te based, In-Sb
Phase-change recording material or a Te-CS ₂ such systems, Pb-Te
_{-Se, Te-C, TeO 2} , Sb-Se, Bi-Te
For write-once recording materials such as CdS, Zn for dielectric films
S, ZnSe, SiO ₂ , Si, Si ₃ N ₄ , AlN, T
Examples thereof include compounds such as iO ₂ , TaO ₂ , and MgF ₂ . In the recording film, examples of the organic compound include methine / polymethine compounds, quinones, naphthoquinones, anthraquinones, phthalocyanines, dithiols, tetrahydrcholines, dioxane, dithiazines, thiabilylium, and porphyrins. Known methods such as a vapor deposition method, a sputtering method, an ion plating method, a dipping method, and a spin coating method are used for forming the functional film. The thickness of the functional coating is usually 100-5
000 angstroms. In the present invention, a protective film is formed on the functional film. As a material for forming the protective film, a known ultraviolet curable resin such as acrylic resin can be used. Uneven pits on the transparent substrate, as described above,
After forming the functional film and the protective film, the optical disk can be manufactured by punching into a disk shape.

Further, uneven pits and a functional film are formed on a support made of a suitable sheet by the same method as described above.
Then, a transparent adhesive layer made of a colorless transparent resin such as an ultraviolet curable resin is applied on the functional coating, and the transparent substrate made of the above norbornene resin is pressure-bonded and punched into a disk shape, and if necessary, the supporting An optical disk can be obtained by a method of peeling off the body. Here, the support is not particularly limited as long as it is a sheet having a light transmittance of 20% or more, but it has a high light transmittance because the irradiation amount can be suppressed to be small when the resin is cured by ultraviolet irradiation. It is preferable to use those having The optical disc of the present invention is a compact disc (CD), laser disc (LD), CD-ROM, CD-I, CD.
It can be suitably used as a high density information recording carrier such as -R, MD, MO, DRAW, E-DRAW. Also, by bonding the optical disk of the present invention to a DV
It is also possible to use a double-sided read optical disc such as D.

[0016]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited by this. In addition,
In Examples, parts and% are based on weight unless otherwise specified. Reference Example 1 8-Methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodeca-3-en 10
2. A toluene solution of 0 g, 60 g of 1,2-dimethoxyethane, 240 g of cyclohexane, 9 g of 1-hexene, and 0.96 mol / l of diethylaluminum chloride.
4 ml was added to an autoclave having a volume of 1 liter. On the other hand, in another flask, 0.1 kg of tungsten hexachloride was added.
20 ml of a 05 mol / l 1,2-dimethoxyethane solution
And 10 ml of a 0.1 mol / l 1,2-dimethoxyethane solution of paraaldehyde were mixed. This mixed solution 4.9
ml was added to the mixture in the autoclave. After sealing, the mixture was heated to 80 ° C. and stirred for 4 hours.
To the obtained polymer solution, a mixed solvent of 2/8 (weight ratio) of 1,2-dimethoxyethane and cyclohexane was added to make the polymer / solvent 1/10 (weight ratio), and then 20 g of triethanolamine was added. Was added and stirred for 10 minutes. 500 g of methanol was added to the polymerization solution, and the mixture was stirred for 30 minutes and allowed to stand. The upper layer separated into two layers was removed, methanol was added again, and the mixture was stirred and allowed to stand, and then the upper layer was removed. The same operation was further performed twice, and the obtained lower layer was cyclohexane, 1,
Dilute appropriately with 2-dimethoxyethane and polymer concentration is 10
% Cyclohexane-1,2-dimethoxyethane solution. 20 g of palladium / silica magnesia [manufactured by Nikki Chemical Co., Ltd., palladium amount = 5%] was added to this solution, and the mixture was reacted in an autoclave at 165 ° C. under a hydrogen pressure of 40 kg / cm ² for 4 hours. Was removed by filtration to obtain a hydrogenated polymer solution. Further, pentaerythrityl-, an antioxidant, was added to this hydrogenated polymer solution.
After adding 0.1% of tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] to the hydrogenated polymer, the solvent was removed at 360 ° C. under reduced pressure. . Next, the molten resin was pelletized by an extruder in an atmosphere under nitrogen, and the weight average molecular weight was 7.0 × 10 ⁴ ,
A thermoplastic resin A having a hydrogenation rate of 99.5% and a glass transition temperature of 168 ° C. was obtained. Reference Example 2 6-Ethylidene-2-tetracyclododecene was added to (a)
After the metathesis ring-opening polymerization as in the case of -1, hydrogenation was carried out,
Thermoplastic resin B pelletized to have a weight average molecular weight of 5.5 × 10 ⁴ , a hydrogenation rate of 99.5%, and a glass transition temperature of 140 ° C.
I got

Example 1 The thermoplastic resin A obtained in Reference Example 1 was extrusion molded at 280 ° C. to obtain a film having a thickness of 0.1 mm. The birefringence of this film was measured by an ellipsometer. On this film, an ultraviolet curable resin composition having the composition shown below (hereinafter referred to as “ultraviolet curable composition a”) is about 30 μm.
And then press the stamper with a roller, and apply 1 J / cm ² of ultraviolet rays from the film side to 0.
The UV curable composition a was cured by irradiation for 5 seconds. <Ultraviolet curable resin composition a> Epoxy acrylate 60 g (Kyoeisha Yushi-Seikagaku Kogyo Epoxy ester 3002A) Trimethylolpropane triacrylate 25 g (Toagosei Kagaku Kogyo Aronix M-309) Acrylic acid 15 g (Osaka Organic Chemical Co., Ltd.) Initiator 4 g (Irgacure 184 manufactured by Ciba Geigy) After curing, the indentation pit surface obtained by peeling the stamper was used, and the vacuum degree was 8 × 10 ^-3 Torr using an in-line sputtering device manufactured by Chugai Furnace Industry Co., Ltd. Then, aluminum was deposited to a thickness of 600 angstroms under the condition that the substrate temperature at the start of sputtering was 70 ° C. Then, the ultraviolet curable resin composition a is applied onto the aluminum surface,
A protective film having a thickness of 10 μm was formed by curing by ultraviolet irradiation, and then a disc-shaped optical disc was obtained. With respect to this optical disk, the pit error rate was measured by a CD error measuring device and evaluated according to the following evaluation criteria. Table 1 shows the evaluation results. ○: Pit error rate 0 or more and less than 20 △: Pit error rate 20 or more and less than 100 ×; Pit error rate 100 or more

Example 2 The procedure of Example 1 was repeated except that the thermoplastic resin B obtained in Reference Example 2 was used instead of the thermoplastic resin A, and the birefringence of the film was measured. An uneven pit layer, an aluminum film, and a protective film were sequentially formed to obtain a disc-shaped optical disc. The pit error rate of the obtained optical disk was measured and evaluated in the same manner as in Example 1. Table 1 shows the evaluation results. Comparative Example 1 An optical disc was prepared in the same manner as in Example 1 using a polycarbonate film (manufactured by Teijin Ltd., thickness: 0.1 mm) instead of the thermoplastic resin A, and evaluated. Table 1 shows the evaluation results. Comparative Example 2 An optical disc was prepared in the same manner as in Example 1 using a polyethylene terephthalate film (manufactured by Toray Industries, Inc., thickness: 0.1 mm) instead of the thermoplastic resin A and evaluated. Table 1 shows the evaluation results.

[0019]

[Table 1]

[0020]

The optical disk of the present invention uses a film having excellent heat resistance, moldability, optical characteristics, dimensional stability, and film adhesion as a transparent substrate, and therefore can sufficiently cope with high density optical disks. It also has excellent durability under high temperature and high humidity.

Claims (3)

[Claims] 1. An optical disc comprising a transparent substrate having a thickness of 30 to 300 μm and made of a thermoplastic norbornene-based resin, on which uneven pits, a functional coating and a protective film are laminated. 2. A transparent substrate made of a thermoplastic norbornene resin is coated with an ultraviolet curable resin and a stamper having concave and convex pits is pressure-bonded, and then the resin is cured by ultraviolet rays, or made of a thermoplastic norbornene resin. A method for manufacturing an optical disc, comprising forming a concave-convex pit on a substrate by directly hot-pressing a stamper on a transparent substrate, forming a functional film, and then forming a protective film. 3. An ultraviolet curable resin is applied on a support,
After pressing a stamper with concave and convex pits, the resin is cured by ultraviolet rays, or by directly pressing the stamper on a transparent substrate to form concave and convex pits, a functional coating is formed, and then a transparent adhesive layer functions. A method for manufacturing an optical disc, which comprises applying a transparent substrate made of a thermoplastic norbornene-based resin after coating on a transparent coating.