JP3525347B2 - Optical recording disc - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording disc, for example, a rewritable type magneto-optical recording disc, a phase change type optical recording disc, and various write-once type optical recording discs.

[0002]

2. Description of the Related Art An optical recording disk is constructed by providing a recording layer on a substrate, and when recording / reproducing the disc, a laser beam or the like is usually irradiated from the substrate side. Therefore, the substrate used is made of a transparent material such as glass or resin. In such a case, a resin substrate is conventionally used as a substrate for an optical recording disc from the viewpoints of weight saving of the disc and ease of forming grooves and pits for tracking, and in particular, polymethylmethacrylate and polycarbonate are used. Is commonly used.

Of these, polymethylmethacrylate has excellent optical properties because it has a small photoelastic coefficient and a very small birefringence, but it is inferior in terms of dimensional stability due to its high water absorption and low heat resistance. ing. Therefore, a polycarbonate having a low water absorption rate and a relatively high heat resistance is often used.

[0004]

However, polycarbonate has a large photoelastic coefficient, polymer chains are easily oriented in the flow direction, and birefringence tends to be large. Especially in recent years
20 for higher density recording and higher transfer rate
Use a large disc with a diameter of 0 mm or more,
It has been attempted to perform recording and reproduction at a high speed rotation of rpm or more, but with such a large diameter size, birefringence occurs during injection molding, and the birefringence is further increased by the application of stress during high speed rotation. As a result, the recording / reproducing output is reduced.

Further, since the water absorption rate is not sufficiently small, the substrate absorbs water and warps, and the rigidity is insufficient, so that surface wobbling occurs and a focus tracking error occurs at a high speed rotation drive of 1800 rpm or more, particularly 3000 rpm or more. Will increase. In addition, there is also a disadvantage that water penetrates from the substrate and the recording layer is corroded.

On the other hand, a high-speed rotation drive which has recently been demanded, particularly 1800 rpm or more, further 3000 rp
In order to support high-speed rotation drive of m or more, it is necessary to consider using a substrate with high mechanical strength.

However, the glass substrate may be damaged if it is dropped or hit by mistake. Particularly, when chemically strengthened glass having high strength is used, there is also a disadvantage that it breaks into small glass pieces and the small pieces scatter. Further, in the case of a glass substrate, a groove or the like as preformat information cannot be formed at the time of molding, resulting in an increase in the number of steps.

On the other hand, in order to prevent mechanical damage to the recording layer due to scratches or the like, it is necessary to provide a protective substrate on the recording layer side of the substrate or to integrate a pair of substrates so that the recording layers are enclosed. is there.

A main object of the present invention is to provide an optical recording disk which can be stably rotated at a high speed without causing surface wobbling or deformation, and which has good recording / reproducing characteristics and durability. .

[0010]

The above objects are achieved by the present invention described in (1) to (6) below. (1) An optical recording disk comprising a resin substrate and a glass protective substrate, wherein a recording layer is formed on the resin substrate, and the recording layer is integrated with the glass protective substrate. The resin contains a cyclic polyolefin having a repeating structural unit represented by the following chemical formula 1, the substrate contains 0.3 to 2 wt% of an alkylphenol condensate, and the substrate is a recording layer side surface layer portion. , Heat softening point 100 to
An optical recording disc having a skin layer of 140 ° C.

[0011]

[Chemical 2]

(2) The optical recording disk according to the above (1), wherein the substrate is rotated at 1800 to 5400 rpm during recording and reproduction of the optical recording disk. (3) The optical recording disk according to (1) or (2) above, wherein the substrate is an injection-molded product of the cyclic polyolefin. (4) The substrate according to any one of (1) to (3) above, which has a thermal softening point of the skin layer and a second thermal softening point higher by 10 to 50 ° C. or more than the thermal softening point. Optical recording disc. (5) The optical recording disc according to any one of (1) to (4) above, wherein the recording layer contains a dye and a reflective layer is provided on the recording layer. (6) The recording layer contains a metal and is formed on the substrate directly or via an underlayer, and the underlayer is composed of an inorganic thin film or is formed of a dielectric material. The optical recording disc according to any one of (1) to (4) above, wherein the recording layer or the underlayer is formed by a vapor phase film forming method.

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

Specific Structure The specific structure of the present invention will be described in detail below.

The substrate in the present invention is substantially transparent (preferably a transmittance of 80% or more) to recording light and reproducing light (semiconductor laser light of about 600 to 900 nm, particularly 700 to 800 nm, especially 780 nm). Formed from resin. This enables recording and reproduction from the back side of the substrate.

As the substrate material, a cyclic polyolefin having a repeating structural unit represented by the following chemical formula 3 is used.

[0024]

[Chemical 3]

In the above chemical formula 3, R ₁ and R ₂ are preferably hydrocarbon residues, and particularly preferably an unsubstituted alkyl group having 1 to 5 carbon atoms.
The cyclic polyolefin used is preferably a homopolymer consisting of only the same repeating unit of the chemical formula 3, but a copolymer consisting of a plurality of repeating units of the chemical formula 3 having different R ₁ , R ₂ or q. May be In addition, depending on the case, it may be a copolymer containing other structural units such as ethylene. The number average molecular weight is preferably 5,000 to 100,000, and particularly preferably 10,000 to 40,000.

In the chemical formula 3, the halogen atom, ester group, nitrile group and pyridyl group may be referred to as polar groups below.

Such a cyclic polyolefin is used as a monomer, for example, norbornene, and an alkyl- and / or alkylidene-substituted product thereof, for example, 5-methyl-2-norbornene, 5,6-dimethyl-2-norbornene, 5 -Ethyl-2-norbornene, 5-butyl-2
-Norbornene, 5-ethylidene-2-norbornene, etc .: dicyclopentadiene, 2,3-dihydrodicyclopentadiene, alkyl substitution products thereof such as methyl, ethyl, propyl, butyl, and polar group substitution products such as halogen: di Methanooctahydronaphthalene, alkyl and / or alkylidene substituents thereof, and polar group substituents such as halogen, for example, 6-methyl-1,4: 5,8
-Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-
Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4: 5,8
-Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-
Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8, 8a-octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4:
5,8-Dimethano-1,4,4a, 5,6,7,8,8
a-octahydronaphthalene and the like; cyclopentadiene trimer and tetramer, for example, 4,9: 5,8-dimethano-3.
a, 4,4a, 5,8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9
-Trimethano-3a, 4,4a, 5,5a, 6,9,9
a, 10,10a, 11,11a-dodecahydro-1H
A saturated polymer produced by hydrogenating a ring-opening polymer obtained by polymerizing by a known ring-opening polymerization method using cyclopentaanthracene and the like.

Regarding such a cyclic polyolefin, JP-A-3-223341 and JP-A-60-
It is described in Japanese Unexamined Patent Publication No. 26024. As this cyclic polyolefin, a commercially available product may be used, and for example, a commercially available product such as Zeonex 280 manufactured by Nippon Zeon Co., Ltd. can be used.

According to the present invention, a lightweight and rigid optical recording disk can be realized in which the protective substrate of the pair of substrates is made of glass and the substrate for the recording layer is made of cyclic polyolefin, and sufficient reliability is achieved. You can get sex.

Further, according to the optical recording disk of the present invention, stable high-speed rotation drive of 1800 rpm or more, particularly 3000 rpm or more can be easily performed, and at the time, surface wobbling and deformation can be prevented. Further, since one of the substrates is made of resin, it is possible to prevent damage when the optical recording disk is dropped or glass scattering when the optical recording disk is damaged.

Particularly, according to an optical recording disk in which a recording layer or the like is formed on a substrate made of a cyclic polyolefin and this is integrated with a protective substrate made of glass, birefringence which is an obstacle to recording and reproduction is prevented. be able to. Since the cyclic polyolefin substrate side on which recording / reproduction is performed is excellent in heat resistance and moisture resistance, it is hardly deformed or deteriorated even when it is stored at a high temperature or a low temperature and a high humidity or a low humidity for a long period of time. In particular, since the cyclic polyolefin has a low water absorption rate, the recording layer is protected from moisture, and the substrate itself does not warp due to water absorption, so that surface wobbling can be effectively prevented.

The thickness of such a substrate is 1.0 to 1.5 mm
The degree. The diameter of the substrate is not particularly limited, but 2
Even with a diameter of 00 mm or more, surface wobbling is extremely small.
It should be noted that a pattern such as preformat information such as grooves and pits can be easily formed on the surface of the substrate during molding.

A hub may be integrated with the substrate. It is preferable to mix glass fiber into the hub in order to prevent cracks and cracks.

A skin layer exists on the surface layer portion of the substrate on the recording layer side, and the thermal softening point of this skin layer is 14
0 ° C or lower, particularly 100 to 140 ° C, more preferably 10
The temperature is preferably 0 to 135 ° C, more preferably 110 to 135 ° C. When the thermal softening point becomes 140 ° C or lower,
In the case where the adhesion between the substrate and the recording layer or the like by the vapor phase film forming method is improved, and a reflective layer is laminated on the dye recording layer,
Recording sensitivity is improved and C / N is improved. However, 100
If the temperature is lower than 0 ° C., for example, heat resistance during lamination of the reflective layer may be deteriorated, dimensional accuracy may be lowered, or coating property of the recording layer may be lowered. In this case, the thermal softening point of the skin layer of the surface layer portion is the temperature measured as described below. First,
The needle is placed on the substrate to be inspected, a load of about 5 g is applied, the temperature is raised from about 30 ° C. at a heating rate of about 2 ° C./min, and the amount of penetration of the needle is measured. The cross section of the needle is a cylinder with a diameter of about 1 mm.

[0037]

The relationship between the temperature thus measured and the needle entry amount is shown in FIG. As shown in FIG. 1, in the substrate of the present invention, a first bending point and a second bending point occur in the temperature characteristic profile of the needle entry amount.

For example, in a cast substrate or a certain type of injection-molded substrate, only one bending point appears in the temperature characteristic of the needle penetration amount, or the first bending point appears only slightly. In addition, the needle entry amount in the first step caused by the first bending point is approximately 200 μm or less. Therefore, it is considered that the first bending point is derived from the softening point of the skin layer on the surface layer of the substrate.

Therefore, in the vicinity of the first bending point of the temperature characteristic profile, the intersection point of the straight line portion before the needle entry and the straight line portion at the time of the first entry is set to T _1, and this is the heat softening of the skin layer. It is defined as a point T ₁ . In the present invention, this T ₁ is regulated as described above.

On the other hand, in the second bending point near the intersection of the linear portion of the time of the first stage enters at the second stage enters a T _2, which defines a second heat softening point T ₂ To do. This second thermal softening point T ₂ is considered to be the thermal softening point at the center of the substrate.

The second heat softening point T ₂ is the first
10 ° C or more from the heat softening point T _{1 of} , more preferably 10
50 ° C higher temperature, 140 ° C or higher, especially 145-1
A temperature of 80 ° C. is preferred. As a result, dimensional accuracy, mechanical characteristics, heat resistance, etc. are excellent.

The skin layer is an SE of the substrate surface layer section.
It can be confirmed from the M image as a layer having a color different from the surroundings, and the thickness thereof is generally 1 to 200 μm, particularly 10 to 100 μm.
Considered to be degree. The temperature characteristic profile of the needle penetration amount may be measured by various devices commercially available as TMA (thermomechanical analyzer, thermomechanical analyzer), for example, 943 thermomechanical analyzer manufactured by DuPont.

In order to form such a skin layer, it is preferable to injection-mold the above cyclic polyolefin.

These are, for example, when cast.
It has the second thermal softening point T ₂ described above.

In order to form a skin layer during injection molding, it is preferable to set the injection pressure to about 250 to 400 kg / cm ² . The melting temperature may be about 300 to 400 ° C., the mold temperature may be about 90 to 120 ° C., and the holding pressure and the mold clamping force may be set under normal conditions. Further, T ₁ also changes depending on the amount of addition of the alkylphenol condensate described below.

If necessary, an oxygen barrier film may be formed on the outer surface of the substrate 2, the outer peripheral surface, or the like. A tracking groove may be formed on the surface of the substrate 2 on which the recording layer 3 is formed.

One or more alkylphenol condensates are added to the resin of such a substrate. As the alkylphenol condensate, the one represented by Chemical formula 4 is preferable.

[0046]

[Chemical 4] (However, R ¹ is an isobutyl group, an isohexyl group, an isoheptyl group, an isooctyl group, an isononyl group, 2,4-
Dimethylheptyl group, decyl group, isododecyl group, tetradecyl group, cyclohexyl group, oleyl group, caproyl group or lauroyl group, A is p-phenylene group, o-
Methyl-p-phenylene group or o- , m -diisobutyl
- p - phenylene group, L is 2-hydroxy -n- propenoxy group, ethenoxy group or 1 - methyl - ethenoxy
Group, n represents an integer of 1 to 30, and Y represents hydrogen or a carboxymethyl group. )

In the above, R ¹ is preferably a substituted or unsubstituted linear or branched alkyl group having about 3 to 30 carbon atoms, and when these have a substituent, a hydroxy group or the like is used as the substituent. preferable.

Further, A is particularly preferably a p-phenylene group. Here, the phenylene group represented by A, or bonded to a substituent such as or branched alkyl group having a straight chain of 1 to 10 carbon atoms, or further binding -O-L _n -Y below You may have.

L is preferably an alkyleneoxy group --R ² O--. In this case, R ² is a substituted or unsubstituted linear or branched alkylene group having about 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, and when these have a substituent, the substituent is hydroxy. A group and the like are preferable. The number of repetitions n of the alkyloxy group or epoxy group L is 1 to 30.
The degree is an integer of 1 to 20, in particular.

[0050]

Table 1 shows specific examples of such alkylphenol condensates.

[0052]

[Table 1]

In order to obtain these alkylphenol condensates, a polymer such as propylene or butylene may be condensed with phenol and then reacted with ethylene oxide or the like in accordance with a usual method for producing a nonionic surfactant. At this time, a long-chain olefin can be used instead of propylene, butylene, or the like.

The decomposition temperature of the alkylphenol condensate used in the present invention is 250 ° C to 350 ° C, more preferably 29 ° C.
A temperature of 0 ° C to 340 ° C (DSC) is preferable. The decomposition temperature is
If it is less than this range, a large amount of gas is generated during molding, or the glass transition point of the substrate is lowered. Further, if it exceeds this range, the compatibility tends to deteriorate.

In the present invention, the substrate is preferably injection molded under the above conditions. Then, the alkylphenol condensate is preferably contained in the resin pellets filled in the injection molding machine used for manufacturing the substrate. Since 96% to 100% of the alkylphenol condensate contained in the resin pellet remains in the substrate when the resin pellet is injection-molded, the physical properties of the substrate can be accurately designed.

In the present invention, the content of the alkylphenol condensate in the substrate resin is 0.3 to 2% by weight, preferably 0.5 to 1.5% by weight. If it exceeds this range, gas is generated in the substrate during molding, and the quality of the optical recording medium deteriorates.

Further, when a coating film of a dye or the like such as a write-once type optical recording disk is used as the recording layer, if the content of the alkylphenol condensate increases, it becomes difficult to coat the dye in the recording layer. Content of material is 2
The upper limit is wt% and the lower the content, the better in terms of coating properties. However, even when a recording layer is formed by a vapor phase film forming method or when a coating film of a dye or the like is provided like another rewritable magneto-optical recording disk or optical recording disk. When a reflective layer is formed thereon by a vapor deposition method, an alkylphenol condensate is added to improve the adhesion between the substrate and the recording layer. In addition, by the addition of alkylphenol condensate,
The injection moldability is improved, and the fluidity of the resin during molding becomes good.

Therefore, the lower limit of the addition amount of the alkylphenol condensate is about 0.3 wt%. If it is less than 0.3 wt%, peeling of the recording layer or the like occurs when it is stored under high temperature and high humidity for a long time, particularly when the recording layer or the like is formed by a vapor deposition method. Such alkylphenol condensates generally function as a resin lubricant.

In the present invention, it is preferable that the substrate contains substantially no lubricant other than the alkylphenol condensate, in particular. Examples of such lubricants include ester-based lubricants such as glycerin monoester, glycerin diester, palmitic acid ester, ethylene glycol monoester, etc .; fatty acid-based additives such as stearic acid, behenic acid, arachidic acid, etc .; fatty acid amide-based additives such as erucinamide. Examples thereof include eicosenoic acid amide. If these lubricants are contained, the coatability of the dye film will decrease.

The substrate resin may contain stabilizers, antioxidants, ultraviolet absorbers and the like.

A recording layer is provided on such a substrate directly or through an appropriate underlayer or intermediate layer.
If necessary, a protective layer, a reflective layer, or the like is provided on the recording layer to form various optical recording disc structures.

In this case, the optical recording disk is a so-called magneto-optical recording disk in which information is magnetically recorded by a modulated heat beam or a modulated magnetic field and the recorded information is magnetically-optically converted and reproduced. , Which has a so-called phase-change type recording layer and has an erasable disc such as an optical recording disc for recording / reproducing by changing the reflectance, or an air sandwich structure, which causes a reflectance change by pit formation, It is either an optical recording disk having a pit formation type recording layer, or a write-once type disk such as a compact disk (CD) or a laser disk (LD) standard compliant optical recording disk in which a reflection layer is closely adhered. May be.

Such an optical recording disc is 1800rp.
It is rotated at a rotation speed of m or more, and recording / reproduction is performed.
When the rotation speed is less than 1800 rpm, the effect of improving the output or reducing noise of the present invention does not become apparent. The upper limit of the rotation speed is generally about 5400 rpm, and the rotation method is CA.
It may be V or CLV.

A preferred example of the optical recording medium 1 of the present invention is shown in FIG. This optical recording medium 1 is a magneto-optical recording disk having a recording layer 3 on a substrate 2.

In the magneto-optical recording disk shown in FIG. 2, a protective layer 4 as an underlayer and an intermediate layer 5 are formed on a substrate 2.
The recording layer 3 is formed via. The intermediate layer 5 is C /
It is provided to improve the N ratio, and is preferably formed of various dielectric materials, and its layer thickness is 30 to 150 nm.
It is preferably about the same. Further, the protective layer 6 may be provided on the recording layer 3 together with the protective layer 4. When used in combination, the compositions of the protective layer 4 and the protective layer 6 may be the same or different. The protective layer 4 and the protective layer 6, which are provided as necessary, are provided for improving the corrosion resistance of the recording layer 3, and it is preferable that at least one of them, and preferably both of them be provided.

These protective layers are preferably composed of an inorganic thin film made of various oxides, carbides, nitrides, sulfides or mixtures thereof. In addition, the protective layers 4 and 6
May be formed of the above intermediate layer material. The thickness of the protective layer is preferably about 30 to 300 nm from the viewpoint of improving corrosion resistance. The protective layers 4 and 6 and the intermediate layer 5 are preferably formed by various vapor phase film forming methods such as sputtering, vapor deposition, and ion plating, and particularly by sputtering.

Information is magnetically recorded on the recording layer 3 by a modulated heat beam or a modulated magnetic field, and the recorded information is magnetic-optically converted and reproduced.

The material of the recording layer 3 is not particularly limited as long as it can perform magneto-optical recording, but an alloy containing a rare earth metal element, particularly an alloy of a rare earth metal and a transition metal is used.
It is preferably formed as an amorphous film by sputtering, vapor deposition, ion plating, etc., particularly by sputtering. Rare earth metals include Tb, Dy, Nd, G
It is preferable to use at least one of d, Sm, and Ce. Fe and Co are preferable as the transition metal.

In this case, the total content of Fe and Co is 65
It is preferably ˜85 at%. And the balance is substantially a rare earth metal. The composition of the recording layer preferably used is TbFeCo, DyTbFeCo, NdDyF.
Examples include eCo and NdGdFeCo. In the recording layer, Cr, Al, Ti, Pt, S in the range of 10 at% or less is used.
i, Mo, Mn, V, Ni, Cu, Zn, Ge, Au, etc. may be contained. In the range of 10 at% or less, S
c, Y, La, Ce, Pr, Pm, Sm, Eu, Ho,
Other rare earth metal elements such as Er, Tm, Yb and Lu may be contained.

The layer thickness of the recording layer 3 is usually 10
It is about 1000 nm.

Even if the recording layer 3 and the intermediate layer 5 as the underlayer are formed by a vapor phase film forming method such as sputtering, the film peeling of the recording layer 3 and the intermediate layer 5 from the substrate 2 is effectively obtained. Can be prevented.

A protective coat 7 is preferably provided on the protective layer 6. The protective coat 7 is made of various resin materials such as an ultraviolet curable resin, and is usually 0.1 to 100 μm.
The layer may be formed to a thickness of about m. The protective coat 7 may be layered or sheet-shaped. The protective coat 7 is
In particular, a coating film containing a radiation-curable compound and a photopolymerization sensitizer is preferably radiation-cured.

Protective substrate 11 adhered on protective coat 7
Is provided in order to effectively prevent damage to the recording layer 3.

The protective substrate 11 used for the resin substrate 2 is made of glass. By thus forming the pair of substrates 2 from cyclic polyolefin and the protective substrate 11 from glass, it is possible to obtain a disc that is lightweight and has high rigidity. Therefore, stable high-speed rotation drive without surface wobbling, for example, rotation drive at 3000 rpm or more can be performed.
Furthermore, since one of the substrates is made of resin, it is possible to prevent damage when the disc is dropped or to prevent glass scattering when broken. Further, in addition to preventing birefringence and improving weather resistance and durability, surface wobbling during high-speed rotation driving can be further reduced.

The glass used for the protective substrate 11 of the present invention is not limited and may be opaque, for example. In addition,
Recording / reproduction is usually performed from the substrate 2 side, but the protective substrate 1
If transparent glass is used as No. 1, recording can be performed from the protective substrate 11 side.

The protective substrate 11 is preferably made of tempered glass. By using tempered glass, higher rigidity and better weather resistance and durability can be obtained.

The tempered glass includes physical tempered glass and chemically tempered glass depending on its tempering method, and is used depending on the application. The tempered glass used in the present invention is not particularly limited, and glass tempered by a usual tempering method is used, but chemically tempered glass is preferably used. The chemically strengthened glass is obtained by, for example, exchanging a part of alkali metal ions as a glass constituent element with another kind of alkali metal ion supplied from the outside, and particularly Li, Na and Na.
By exchanging K and K, a compressive stress layer is formed in the glass to enhance mechanical strength. Chemical strengthening treatment is usually
It is carried out by heating and melting an alkali salt such as nitrate or sulfate, and immersing the glass to be treated in the melt for several hours to several tens of hours.

The glass produced by such a chemical strengthening treatment is usually a surface strengthened glass in which a compressive stress layer is formed only near the glass surface. In this case, the thickness of the compressive stress layer is preferably 10 to 200 μm, particularly 30 to 75 μm.

The chemically strengthened glass used is soda
It may be one obtained by subjecting the lime / silicate glass or the like to the above chemical strengthening treatment, but since it has particularly high mechanical strength,
Alumina silicate glass that has been chemically strengthened is preferably used. As alumina silicate glass,
A1 ₂ O ₃ content of 10 wt% due to high mechanical strength
The above is preferable, and it is particularly preferable to use one containing 15 to 30 wt% of A1 ₂ O ₃ .

The composition range of the alumina silicate glass preferably used in the present invention is shown below. SiO ₂ 50-60 wt% A1 ₂ O ₃ 15-30 wt% B ₂ O ₃ 1-10 wt% R ^I ₂ O 10-25 wt% R ^II O 1-10 wt% (wherein R ^I and R ^II are monovalent, respectively) And divalent metal) TiO ₂ etc. 0-5 wt%

The K ⁺ substitution rate is 0.01 to 1 mg / c.
It is preferably about m ³ .

The thickness of the protective substrate 11 is about 0.5 to 2.0 mm in order to secure rigidity. The shape of the protective substrate 11 may be the same as the shape of the substrate 2.

In the present invention, the protective substrate 11 is the adhesive layer 12
Are integrated with the substrate 2. Various known adhesives can be used for this adhesion.

Besides, the present invention can be applied to an optical recording disk having a so-called phase change type recording layer and recording / reproducing by changing the reflectance.

Examples of such a recording layer include Te-Se type alloys described in Japanese Patent Publication No. 54-41902, Japanese Patent No. 100004835 and Te-Ge type alloys described in Japanese Patent Application Laid-Open No. 62-76035. JP-A-63-56827
Te-In alloys described in Japanese Patent Application No. 61-307
No. 298, Japanese Patent Application No. 61-307299, etc.
e-Sn alloy, JP-A-58-54338, Patent No. 9
74257, Patent 974258, Patent 9742
No. 57 Te oxide type, other various Te, S
Color change occurs due to change in crystal structure of Ag-Zn, Ag-Al-Cu, Cu-Al, etc. which causes amorphous-crystalline transition such as chalcogen based on e, Ge-Sn, Si-Sn, etc. Examples include alloys, alloys such as In—Sb that cause a change in crystal grain size.

In any of these cases, an underlayer or a protective layer formed by a vapor phase film forming method may be included.

As described above, according to the present invention, the recording layer and the underlayer are provided by the vapor phase film forming method, in particular, the sputtering, and in particular, the phase change type optical recording disk having the metal recording layer and the rare earth metal element. It is suitable for a magneto-optical recording medium having a recording layer containing a metal such as.

Another preferred example of the optical recording medium of the present invention is shown in FIG. This optical recording medium 1 is a close contact type optical recording disc having a recording layer 3 containing a dye on a substrate 2, and a reflective layer 8 and a protective film 9 formed in close contact with the recording layer 3.

A groove 23 for tracking is preferably formed on the surface of the substrate 2 on which the recording layer 3 is formed. The groove 23 is preferably a spiral continuous groove, having a depth of 250 to 1800 A and a width of 0.2 to.
1.1 μm, especially 0.3 to 0.6 μm, land (the portion between adjacent grooves) width is 0.5 to 1.4 μm,
In particular, it is preferably 1.0 to 1.3 μm. With such a configuration of the groove, a good tracking signal can be obtained without lowering the reflection level of the groove portion. It should be noted that the groove may be provided with unevenness for address signals.

In the present invention, when the substrate 2 has a groove, it is preferable that the recording light is applied to the recording layer 3 in the groove 23. That is, the optical recording medium of the present invention is preferably used as an optical recording medium for groove recording. By using groove recording, the effective thickness of the recording layer can be increased.

In this case, the recording layer 3 is preferably formed by compatibilizing one kind or two or more kinds of dyes. In this case, a quencher may be mixed with the light absorbing dye, and an ionic combination of a dye cation and a quencher anion may be used as the light absorbing dye.

The extinction coefficient (imaginary part of complex refractive index) k of the recording layer 3 at the wavelengths of the recording light and the reproducing light is 0.03 to 0.
It is preferably 25. When k is less than 0.03, the absorptivity of the recording layer is lowered, and it becomes difficult to perform recording with normal recording power. Further, when k exceeds 0.25, the reflectance becomes less than 60%, and it becomes difficult to perform reproduction according to the CD standard.

The refractive index (real part of complex refractive index) n is
It is preferably 1.8 to 4.0, more preferably 2.2 to 3.3. When n <1.8, the reflectance decreases and C
Reproduction according to the D standard tends to be difficult. Also, n>
To obtain 4.0, it is difficult to obtain the raw material dye.

When measuring n and k, a recording layer is formed on a predetermined transparent substrate to a thickness of, for example, about 400 to 100 A under actual conditions to prepare a measurement sample.
Then, the reflectance through the substrate or from the recording layer side is measured. The reflectance is measured by specular reflection (about 5 °) using the recording / reproducing light wavelength. In addition, the transmittance of the sample is measured. From these measured values, for example, n and k may be calculated according to Kyoritsu Zensho "Optical" Kozo Ishiguro P168-178.

The light absorbing dye to be used is not particularly limited as long as it has an absorption maximum of 600 to 900 nm, preferably 600 to 800 nm, and more preferably 650 to 750 nm. One or more of phthalocyanine type, anthraquinone type, azo type, triphenylmethane type, pyrylium or thiapyrylium salt type, squarylium type, croconium type and metal complex dye type are preferable. The cyanine dye is preferably a cyanine dye having an indolenine ring, particularly a benzoindolenine ring.

The recording layer 3 is formed by coating. When the layer is formed by coating, the solvent may be a ketone type, an ester type, an ether type, an aromatic type, an alkyl halide type,
Although various alcohol solvents can be used, it is particularly preferable to use ketone solvents such as cyclohexanone, methyl ethyl ketone and methyl isobutyl ketone. By using a ketone solvent, the solubility of the dye is improved, the film quality of the dye film is improved, the coatability is improved, and the ketone solvent does not chemically damage the surface of the substrate. The quality of is greatly improved.

The thickness of the recording layer 3 is preferably 500 to 2000A. The reflectance decreases outside this range.

A reflective layer 8 is provided directly on the recording layer 3 so as to be in close contact therewith. The reflective layer 8 may be made of a high-reflectance metal or alloy such as Au, Ag and Cu.

The reflective layer 8 preferably has a thickness of 500 A or more, and may be formed by vapor deposition, sputtering or the like.
Although the upper limit of the thickness is not particularly limited, it is preferably about 1200 A or less in consideration of cost, production work time and the like. Accordingly, the reflectance of the reflective layer 4 alone is
The reflectance of 90% or more, the reflectance of the unrecorded portion of the medium through the substrate is 60% or more, and particularly 70% or more.

A protective film 9 is preferably provided on the reflective layer 8. The protective film 9 may be formed of various resin materials such as an ultraviolet curable resin, and usually has a thickness of about 0.1 to 100 μm. The protective film 9 may be layered or sheet-shaped. The protective film 9 is preferably a radiation-cured coating film containing a radiation-curable compound and a photopolymerization sensitizer.

The hardness of the protective film 9 is preferably H-8H, particularly 2H-7H, in pencil hardness (JIS K-5400) at 25 ° C.

With this structure, the eye pattern becomes good and the jitter is remarkably reduced. Also,
No peeling occurs between the protective film and the reflective layer even when stored under conditions of high temperature and high humidity or changes in temperature and humidity. More specifically, if the hardness of the protective film is softer than H, the eye pattern will be disturbed and jitter will increase, and if it is harder than 8H, the coating film will become brittle and the film forming ability will decrease, and also the adhesive force with the reflective layer will decrease. To do.

The radiation-curable compound used for forming such a protective film preferably contains an oligoester acrylate. The oligoester acrylate is an oligoester compound having a plurality of acrylate groups or methacrylate groups. And a preferable oligoester acrylate has a molecular weight of 1,000 to 10,000,
Preferably it is 2000-7000 and the degree of polymerization is 2-1.
0, preferably 3 to 5 can be mentioned. In addition, among these, acrylate group or methacrylate group is 2
Polyfunctional oligoester acrylates with ~ 6, preferably 3-6, are preferred. Further, in addition to or instead of the above compounds, a radiation curable compound obtained by subjecting a thermoplastic resin to radiation-sensitive modification may be used.

The thickness of the protective film of such a radiation-curable compound is 0.1 to 30 μm, more preferably 1 to 10 μm.
Is. If this film thickness is less than 0.1 μm, it is difficult to form a uniform film, the moisture-proof effect in an atmosphere with high humidity is not sufficient, and the durability of the recording layer decreases. Moreover, the effect of preventing jitter is reduced. If it exceeds 30 μm, warpage of the recording medium and cracks in the protective film are likely to occur due to shrinkage during curing of the resin film.

Such a coating film is usually formed by spinner coating, gravure coating, spray coating, dipping, etc.
Layers may be formed by combining various known methods. The layer forming conditions of the coating film at this time may be appropriately determined in consideration of the viscosity of the mixture of the coating film composition, the target coating film thickness, and the like.

In the present invention, examples of the radiation applied to the coating film include ultraviolet rays and electron beams, and ultraviolet rays are preferable. When ultraviolet rays are used, a photopolymerization sensitizer is usually added to the above radiation-curable compounds.

Examples of the photopolymerization sensitizer include benzoin compounds such as benzoin methyl ether, benzoin ethyl ether, α-methylbenzoin, α-chlordeoxybenzoin, benzophenone, acetophenone, morpholinodimethylmethyl-4-methylthiophenyl ketone, and the like.
Examples thereof include ketones such as bisdialkylaminobenzophenone, quinones such as anthraquinone and phenanthraquinone, and sulfides such as benzyl disulfide and tetramethylthiuram monosulfide.

In order to cure the coating film containing the photopolymerization sensitizer and the radiation-curable compound with ultraviolet rays, various known methods may be used. For example, a UV bulb such as a xenon discharge tube or a mercury discharge tube may be used. An electron beam can also be used depending on the case.

On the protective film 9 as described above, the same protective substrate 11 made of glass as described above is adhered.

In order to perform recording or additional recording on the optical recording medium 1 having such a structure, recording light of 780 nm, for example, is irradiated in a pulsed form through the substrate 2.

As a result, the recording layer 3 absorbs light and generates heat, and at the same time, the substrate 2 is also heated. As a result, in the vicinity of the interface between the substrate 2 and the recording layer 3, the recording layer material such as a dye is melted or decomposed, pressure is applied to the interface between the recording layer 3 and the substrate 2, and the bottom wall or side wall of the groove 23 is removed. Transform it.

In this case, the decomposed product layer 101 containing the melted product or decomposed product of the recording layer 3 usually remains in a shape that covers the bottom of the groove 23 and the boundary with the substrate 2. Moreover,
Since the surface layer of the substrate has a predetermined thermal softening point, the decomposed product layer 10
1 further penetrates into the substrate side in a convex shape, and the pit portion 10 is formed to have a larger shape. The dent amount of the substrate 2 is larger as the dimension of the pit portion 10 is larger, and is a depth of about 300 A or less.

The material of the decomposed material layer 101 is a material which does not substantially include the substrate material, and is composed of a decomposed material of the recording layer material or a mixture of the decomposed material of the recording layer material and the recording layer material. The decomposed material layer 101 is the recording layer 3 in the groove.
The thickness is usually about 30 to 100%. Then, usually, a void is formed on the decomposed material layer 101 at the interface with the reflective layer, and the decomposed material layer 101 and the void 103 are formed in the pit portion 10. The void 103 is usually about 5 to 70% of the thickness of the recording layer 3.

The outer shape and concave shape of the pit portion are also good. The presence of the skin layer improves the pit shape as well as the pit shape, improving C / N and improving sensitivity.

Although the optical recording medium in which the reflective layer is closely adhered to the recording layer has been described above, the reflective layer is not laminated to the recording layer, and the recording layer is internally sealed via a void, or
Alternatively, the present invention can be effectively applied to an optical recording disk or the like which has a so-called air sandwich structure in which recording layers are opposed to each other with a gap therebetween and changes in reflectance due to pit formation.

[0116]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention.

Example 1 As a cyclic polyolefin having the repeating unit of the above Chemical formula 3, a commercially available pellet of cyclic polyolefin having a molecular weight of 29,000, Zeonex 280 manufactured by Nippon Zeon Co., Ltd. was obtained.
The cyclic polyolefin pellets have the following chemical formulas 5 and 6
Of two or more alkylphenol condensates represented by
% And sample No. 1.

[0118]

[Chemical 5]

[0119]

[Chemical 6]

This is melted at 350 ° C., and the mold temperature is 10
Injection molding at 0 ℃, injection pressure 350kg / cm ² , 300mm diameter,
Substrate sample No. 1 having a thickness of 1.2 mm was obtained.

The thermal softening point of the substrate was measured by TMA as follows. Needle cross section: 1 mm diameter cylinder load: 5 g Temperature rising rate: 2 ° C / min

Under the above conditions, the temperature profile of the needle penetration amount was measured, and the first and second thermal softening points T ₁ and T ₂ were calculated. As shown in Table 2, T ₁ is 124 ° C and T ₂ is 156 ° C.
Met. Also, from the SEM image of this substrate, it was considered that the thickness of the skin layer was about 100 μm or less.

A glassy protective film was formed on this substrate by high-frequency magnetron sputtering to have a layer thickness of 40 nm.
An intermediate layer made of SiN _x was formed on the protective layer by high frequency magnetron sputtering to have a layer thickness of 80 nm. next,
A recording layer having a composition of Tb ₂₃ Fe ₇₂ Co ₅ was formed on the intermediate layer by sputtering to have a layer thickness of 80 nm.

Further, a protective layer having the same composition as the protective layer was provided on the recording layer by high frequency magnetron sputtering to a layer thickness of 100 nm, and a protective coat was provided on the protective layer. The protective coat is formed by applying an ultraviolet curable resin containing oligoester acrylate and then ultraviolet curing to form a protective film having a thickness of 5 μm.
Then, a glass protective substrate was adhered to produce a single-sided recording type magneto-optical recording disk shown in FIG.

The glass-made protective substrate was a chemically strengthened glass of alumina silicate, and had a disk shape with an outer diameter of 300 mm and a thickness of 1.2 mm.

The adhesive layer is formed by a roll coater using a hot melt adhesive containing a pinene resin,
Its thickness was 80 μm.

Separately, as a comparative example, a bisphenol A type polycarbonate (number average molecular weight 1500
The substrate 0) was injection-molded under the conditions of a melting temperature of 340 ° C., a mold temperature of 100 ° C., and an injection pressure of 300 kg / cm ² , and Comparative Magneto-Optical Recording Disk Sample No. 2 was prepared in the same manner.

Instantaneous surface shake acceleration was measured for these magneto-optical recording disks. The measurement was performed at a disk rotation speed of 1800 rpm and a radius of 60 to 1 from the disk center.
A range of 30 mm was performed at 5 mm intervals. The number of measurement samples was three for each magneto-optical recording disk, and the average value of the maximum surface wobbling acceleration of each sample was obtained.

The measurement was carried out under the conditions of temperature 80 ° C. and humidity RH = 80%.

The surface wobbling acceleration is expressed by the acceleration of the optical pickup during focusing servo, and indicates the flatness of the substrate on which the tracking groove is formed.
According to the ISO standard, this value is preferably 20 m / s ² or less, particularly 10 m / s ² or less for a magneto-optical recording disk having an outer diameter of 130 mm.

As a result, the instantaneous surface wobbling acceleration of the product of the present invention in which the cyclic polyolefin was used as the substrate was 20 m / s ² or less, whereas the comparative sample No. in which polycarbonate was used as the substrate was used. At 2, it was 55 m / s ² , which was a remarkable effect.

Example 2 In Example 1, the contents of the alkylphenol condensate of sample No. 1 were 0 wt%, 0.8 wt%, and 2.3.
Injection molding under the same conditions in place of wt%, sample No. 3 ~
I got No. 5. In addition, using sample No. 1 pellets,
Sample No. 6 having a skin layer thermal softening point of more than 140 ° C. was prepared by the same injection molding except that the injection pressure was 370 kg / cm ² , the melting temperature was 330 ° C., and the mold temperature was 80 ° C.

However, in Sample No. 5 in which the content of the alkylphenol condensate was 2.3 wt%, gas unevenness was observed in the substrate.

These sample No. 1 and sample No.
The same magneto-optical disk as in Example 1 was prepared using Sample No. 3, Sample No. 4 and Sample No. 6, and a corrosion resistance test was conducted.

In the corrosion resistance test, the sample was heated at a temperature of 80 ° C.
Leave the substrate for 2500 hours under the condition of humidity 85% RH,
The state between the laminates was visually and visually observed.

Among these states, ∘ indicates that there is no abnormality at all, ∘ indicates that slight swelling of about 10 μm to 100 μm occurs, and ∘ indicates that this swelling occurs partially but clearly. Was evaluated as Δ, and the case where peeling occurred also on the entire surface was evaluated as x. The results are shown in Table 2.

[0137]

[Table 2]

Sample Nos. 3, 4, and 6 had 20
The instantaneous surface shake acceleration of less than m / s ² was shown.

Example 3 Substrate sample No. 1 and sample No. used in Example 1
3, sample No. 4 to sample No. 6, and sample No.
In place of the alkylphenol condensate in 3, the sample No. 7 was prepared in which the total amount of glycerin monoester and glycerin diester was 1.2 wt% as a lubricant.

A recording layer containing a cyanine dye was formed on these substrates. For the recording layer, the substrate is 500 rp
Spin coating was performed while rotating at m. A cyclohexanone solution was used as the coating solution. The thickness of the dye layer after drying was 140 A in the groove portion and 90 A in the land portion. The refractive index (n) of the recording layer is 2,
6, the extinction coefficient (k) was 0.06. n and k
Was determined by forming a solution containing the above dye on a measurement substrate to a dry film thickness of 100 A as a test recording layer, and measuring n and k of the test recording layer. This measurement is based on "Optics" (Kozo Ishiguro, Kyoritsu Zensho) No. 168-1.
This was carried out according to the description on page 78.

It was noted that Sample No. 5 and No. 7 could not be applied.

Further, an Au film having a thickness of 1000 A was formed on the recording layer by sputtering to form a reflective layer, and a UV-curable resin containing oligoester acrylate was applied and then UV-cured to a thickness of 5 μm. As a protective film, an optical recording disk sample was obtained. The pencil hardness of this film was 2H.

The sensitivity of each of the obtained samples was measured. The recording sensitivity was defined as the recording power at which the maximum signal was obtained at a recording frequency of 8 MHz at 1800 rpm. The results are shown in Table 3.

[0144]

[Table 3]

From the results shown in Table 3, the effect of the present invention is clear.

The instantaneous surface blur acceleration was 20 m / s ² or less in all of Sample Nos. 1, 3, 4, and 6.

[0147]

Since the optical recording disk of the present invention has less surface deviation of the substrate, it has few focus tracking errors even when used at high speed. Further, by forming a predetermined skin layer, the recording sensitivity is improved, or the adhesion between the recording layer and the substrate is improved, so that the durability can be improved even when stored under high temperature and high humidity. it can. Further, the coating property of the recording layer is also good.

[Brief description of drawings]

FIG. 1 is a graph for explaining a thermal softening point of an optical recording disk of the present invention.

FIG. 2 is a partial sectional view showing an example of an optical recording disk of the present invention.

FIG. 3 is a partial cross-sectional view showing another example of the optical recording disk 11 of the present invention.

[Explanation of symbols]

1 Optical Recording Disk 2 Substrate 21 Land Part 23 Groove 24 Substrate Pit Part 3 Recording Layer 4 Protective Layer 5 Intermediate Layer 6 Protective Layer 7 Protective Coating 8 Reflective Layer 9 Protective Film 10 Pit Part 101 Decomposition Layer 103 Void 11 Protective Substrate 12 Adhesion Agent layer T ₁ First thermal softening point T ₂ Second thermal softening point

Continuation of front page (51) Int.Cl. ⁷ Identification code FI G11B 11/105 521 G11B 11/105 521A 521D (72) Inventor Setsuko Shibuya 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDK Corporation ( 56) References JP-A-57-66538 (JP, A) JP-A-2-223477 (JP, A) JP-A-60-168708 (JP, A) JP-A-5-39403 (JP, A) Flat 4-161408 (JP, A) JP 4-251449 (JP, A) Actual flat 2-135925 (JP, U)

Claims (4)

(57) [Claims] 1. An optical recording disk comprising a resin substrate and a glass protective substrate, wherein a recording layer is formed on the resin substrate, and the recording layer is integrated with the glass protective substrate. The resin contains a cyclic polyolefin having a repeating structural unit represented by the following [Chemical formula 1], and the substrate contains 0.3 to 2 wt% of an alkylphenol condensate represented by the following [Chemical formula 4]. The substrate is then injection molded
An optical recording disk having a skin layer having a thermal softening point of 100 to 140 ° C. on the surface layer portion on the recording layer side by being formed . [Chemical 1] (In the above formula, q is O, 1, 2, 3 or 4, and Rl and R2 are
Each represents a hydrogen atom, a halogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, an ethylidene group, a methoxycarbonyl group, a cyano group or a pyridyl group, and these may be the same or different. Rl and R2 may combine with each other to form a ring. ) [Chemical 4] (However, R ¹ is an isobutyl group, isohexyl group, isoheptyl group, isooctyl group, isononyl group, 2,4-dimethylheptyl group, decyl group, isododecyl group, tetradecyl group, cyclohexyl group, oleyl group, caproyl group or lauroyl group. , A is a p-phenylene group, o-methyl-p-phenylene group or o-, m-diisobutyl-p-phenylene group, L is a 2-hydroxy-n-propenoxy group, an ethenoxy group or a 1-methyl-ethenoxy group. Group, n represents an integer of 1 to 30, and Y represents hydrogen or a carboxymethyl group.) 2. The substrate has a thermal softening point of the skin layer,
The optical recording disk according to claim 1, which has a first heat softening point which is 10 to 50 ° C. higher than the heat softening point. 3. The optical recording disk according to claim 1, wherein the recording layer contains a dye and a reflective layer is provided on the recording layer. 4. The recording layer contains a metal and is formed on the substrate directly or via an underlayer, and the underlayer is composed of an inorganic thin film, or a dielectric material. 3. The optical recording disk according to claim 1 , wherein the recording layer or the underlayer directly formed on the substrate is formed by a vapor deposition method.