JP3072905B2 - optical disk - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical disc, particularly a magneto-optical recording disc, a phase-change optical recording disc, a pit-forming optical recording disc, a read-only optical disc, and the like.

<Prior Art> An optical disc, for example, a magneto-optical recording disc, is formed by sequentially laminating a resin layer, a recording layer, a protective coat, and the like on a substrate.

In this case, an ultraviolet curable compound is usually used for the resin layer. Then, using a so-called 2P method, a resin layer having a pattern of tracking grooves and pits or recording pits is formed on the substrate.

In the 2P method, first, an ultraviolet-curable compound is spread on the surface of a stamper having a matrix pattern of the pattern, and a disk-shaped substrate is pressed onto the ultraviolet-curable compound. Next, after curing by irradiation with ultraviolet rays, the stamper and the resin are separated. Thereby, the resin layer to which the matrix pattern has been transferred can be formed on the substrate.

<Problems to be Solved by the Invention> However, some resin layers obtained by curing a conventional ultraviolet-curable compound have a relatively high tackiness and are difficult to peel off from a stamper.

In addition, at the time of peeling or after the peeling, the shape of the groove or pit is not maintained, and a good transfer shape may not be obtained.

In addition, heat resistance, moisture resistance, and film strength are insufficient.

For example, when forming the recording layer by sputtering, 60
Since the resin layer is placed at a temperature of about 100 ° C., the resin layer is deformed by heat, and the mechanical accuracy of the disk is reduced.

Further, when storing or using the disk under high temperature and high humidity, the resin layer is deformed, and the mechanical accuracy of the disk is reduced.

As a result, when the disk is rotated, surface eccentricity of the disk occurs, which makes tracking difficult and causes an error.

An object of the present invention is to form a resin layer by the 2P method, which is easy to peel off from a stamper, can maintain good shapes of grooves and pits, and has a resin layer having high heat resistance, moisture resistance, and film strength. Another object of the present invention is to provide an optical disk having high mechanical accuracy.

<Means for Solving the Problems> Such an object is achieved by the present invention described below.

(1) a resin layer cured by irradiation with radiation on a substrate, the resin layer having a frequency of 10 Hz, an elastic modulus at a temperature of 20 to 100 ° C. of 200 kgf / mm ² or more, and a frequency of 10 Hz of the resin layer; An optical disc having a mechanical loss coefficient tan δ at a temperature of 20 to 100 ° C. of 0.01 to 0.2; and a metal recording layer formed on the resin layer.

<Effect> The elastic modulus of the resin layer of the optical disc of the present invention is 200 kgf / mm ²
Above, the adhesiveness is low.

Therefore, when the resin layer is formed on the substrate by the 2P method, the resin can be easily separated from the stamper.

In addition, since the shape of the formed groove or pit can be maintained as it is, it is possible to form a resin layer on which the master pattern of the stamper is accurately transferred.

Further, the resin layer of the optical disc of the present invention has high heat resistance and moisture resistance, and high film strength.

For this reason, when placed under high temperature and high humidity, for example, when forming the recording layer by sputtering, or when storing and using the optical disk under high temperature and high humidity, the resin layer does not deform, Can maintain high mechanical accuracy.

In addition, since the elastic modulus of the resin layer is not determined only by the ultraviolet-curable compound used, in the present invention, the ultraviolet-curable compound, the photopolymerization initiator, or their contents, ultraviolet irradiation conditions, atmosphere, etc. A desired resin layer is formed by combining the above conditions.

<Specific Configuration> Hereinafter, a specific configuration of the present invention will be described in detail.

The optical disk of the present invention has a resin layer cured by irradiation with radiation on a substrate.

In this case, the present invention is both a read-only optical disk that previously carries information and an optical recording disk that has a recording layer capable of carrying information.

However, here, the magneto-optical recording disk shown in FIG. 1 will be described as a preferred example.

This magneto-optical recording disk 1 has a single-sided recording in which a resin layer 3, a protective layer 4, an intermediate layer 5, a recording layer 6, a protective layer 7, a protective coat 8, an adhesive layer 9, and a protective substrate 10 are sequentially formed on a substrate 2. Type.

In the present invention, the substrate 2 is transparent to recording light and reproduction light, and its material may be glass or resin known as a substrate material of a conventional optical disk, and may be appropriately set according to the application. Selected. In this case, it is preferably made of resin or glass, and more preferably made of glass.

When the substrate 2 is made of glass, heat resistance and moisture resistance are improved and birefringence hardly occurs.

In the case of a glass substrate, it is preferable to be made of tempered glass. By using tempered glass, higher rigidity and better weather resistance and durability can be obtained.

There is no particular limitation on the tempered glass used in the present invention, and physical strengthened glass or chemically strengthened glass strengthened by a normal tempering method may be used, but preferably chemically strengthened glass is used.

In the case of a resin substrate, for example, acrylic resin, polycarbonate, epoxy resin, polymethylpentene, polyolefin and the like are suitable.

The shape of the substrate 2 is a disk shape and the outer diameter is usually 50
The diameter is usually about 15 to 60 mm, and the thickness is usually about 0.5 to 2 mm.

 The substrate 2 may be manufactured according to a known method.

 On the substrate 2, a resin layer 3 is provided.

The resin layer 3 is composed of a radiation-curable compound or a composition obtained by curing the composition by irradiating it with radiation such as ultraviolet rays or electron beams. The resin layer 3 has pits or grooves on its surface for tracking, addressing, and the like. Etc. have a predetermined pattern.

The elastic modulus of the cured resin layer 3 at a temperature of 20 Hz to 100 ° C. at a frequency of 10 Hz is 200 kgf / mm ² or more.

When the elastic modulus is less than 200 kgf / mm ² , heat resistance and the like are insufficient.

However, if it is too large, the resin layer 3 becomes too brittle, and cracks may occur due to changes in temperature and humidity. Therefore, it is preferably 200 to 1500 kgf / mm ² .

And, more preferably 220~1500kgf / mm ^2, in particular 250
It is a ~1000kgf / mm ^2.

When the elastic modulus is in the above range, the effect of the present invention is further improved.

Further, the mechanical loss coefficient tan δ at each temperature within the temperature range of 10 Hz and 20 to 100 ° C. of the cured resin layer 3 is 0.0
1 to 0,2.

Beyond the above range, the viscosity of the material will increase,
The groove shape changes easily due to heat.

Below the range, the resin layer 3 itself becomes too brittle,
Cracks tend to occur due to changes in temperature and humidity. In addition, the film forming ability falls.

And more preferably 0.05-0.2, especially 0.05-0.18
It is preferred that

When tan δ is within the above range, the effects of the present invention are further improved.

The elastic modulus and the mechanical loss coefficient tan δ are measured as follows.

The resin layer is formed, for example, on release paper so as to have a thickness of 100 to 500 μm. Next, the resin layer was peeled off from the release paper, and using a viscoelasticity measuring device, the excitation frequency was 10 Hz by the forced vibration method
(Sinusoidal wave), measured between 0 and 150 ° C.

The resin material constituting the resin layer 3 is not particularly limited as long as the above elastic modulus can be obtained, and may be appropriately selected from various radiation-curable compounds used in a so-called 2P method.

As the monomer to be used, monofunctional, bifunctional, trifunctional or polyfunctional ester acrylate, urethane acrylate, epoxy acrylate and the like are preferable.

In this case, only one type of monomer may be used, but two types, or in some cases, three or more types, may be used in view of the above-mentioned elastic modulus and tan δ being easily obtained.

And among the above monomers, trimethylolpropane triacrylate, pentaerythritol triacrylate, trifunctional monomers such as trimethylolpropane trimethacrylate, neopentyl glycol diacrylate hydroxypivalate, neopentyl glycol diacrylate hydroxycaperate-modified hydroxypivalate neopentyl glycol diacrylate, The combination with a bifunctional monomer such as neopentyl glycol dimethacrylate is optimal.

Further, instead of the monomer or in addition to the monomer, one or more oligomers may be used in combination.

As the oligomer, oligoester acrylate and the like are preferable.

As the polyfunctional oligoester acrylate, those commercially available as ARONIX M-8100 and M-6500 (manufactured by Toagosei Chemical Co., Ltd.) can be used, and these are those represented by the following formulas (A) and (B). It is.

_{(B) AM-N n M} -A (M-6500) A: acrylic acid, X: polyhydric alcohols, M: 2 dihydric alcohols, Y: polybasic acid N: 2 dibasic acid also added to the monomer or oligomer, Usually, a photopolymerization initiator is added.

There is no particular limitation on the photopolymerization initiator used, for example,
2,2-dimethoxy-2-phenylacetophenone, 2-
Methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, benzoin, benzophenone, benzyl and the like are preferred.

The content of the photopolymerization initiator is 1 to 10% by weight, particularly 3 to 5%.
% By weight is preferred.

In this case, in the present invention, it is preferable that additives such as a solvent are not contained.

It is preferable to form such a resin layer 3 by a known 2P method.

In the 2P method, first, a radiation-curable compound, preferably a compound obtained by adding a photopolymerization initiator to the radiation-curable compound, is spread on the surface of a stamper having a predetermined pattern, and the substrate 2 is pressed against the coating film. By this pressing, the pattern on the stamper surface is transferred to the coating film surface.

Next, the coating film is cured by irradiating radiation, preferably ultraviolet light, through the substrate 2 to bond the resin to the substrate 2 and then peel off the resin and the stamper.

Through the above steps, the resin layer 3 to which the pattern of the stamper has been transferred is formed on the surface of the substrate 2.

In the present invention, as described above, the cured resin layer 3
Since the elastic modulus of the resin is regulated to 200 kgf / mm ² or more, the resin and the stamper can be easily separated, and the formed grooves and pits can be maintained in a good shape.

In order to cure the coating film with ultraviolet rays, various known methods may be used.

For example, a xenon discharge tube, an ultraviolet lamp such as a high-pressure mercury lamp, or the like may be used.

In some cases, an electron beam or the like can be used.

The conditions for curing the coating film are not particularly limited, and for example, the following conditions may be used.

Irradiation dose: about 0.3 to ² joules / cm ² The atmosphere at the time of curing is not particularly limited, and may be, for example, in the air.

However, when a radiation-curable compound having anaerobic curability is used, an inert gas atmosphere such as Ar, an N ₂ gas atmosphere, or the like is suitable.

The thickness of the resin layer 3 formed in this manner is preferably 5 to 100 μm, more preferably 30 to 50 μm.

If it is less than the above range, the resin layer 3 is too thin, and it is easy to be insufficiently cured.

When the thickness exceeds the above range, the resin layer 3 is too thick, so that the inside of the layer is apt to be uncured and wrinkles are easily generated.

The intermediate layer 5 is provided to improve the C / N ratio, and is preferably formed of various dielectric materials, and preferably has a thickness of about 30 to 150 nm.

Incidentally, such a material for the intermediate layer may be provided as a protective layer 7 on the recording layer 6 described later, and used together with the intermediate layer 5. When used together, the compositions of the intermediate layer 5 and the protective layer 7 may be the same or different.

The protective layer 4 and the protective layer 7, which are provided as necessary,
It is provided to improve the corrosion resistance of the recording layer 6,
It is preferable that at least one of them, and preferably both of them are provided. These protective layers are preferably composed of an inorganic thin film made of various oxides, carbides, nitrides, sulfides or mixtures thereof. Further, as described above, it may be formed of the above-mentioned intermediate layer material. The thickness of the protective layer is preferably about 30 to 300 nm from the viewpoint of improving corrosion resistance.

Such protective layers 4 and 7 and the intermediate layer 5 are preferably formed by various vapor deposition methods such as a sputtering method.

In the recording layer 6, information is magnetically recorded by a modulated heat beam or a modulated magnetic field, and the recorded information is reproduced by magneto-optical conversion.

The material of the recording layer 6 is not particularly limited as long as it can perform magneto-optical recording. An alloy containing a rare earth metal element, particularly an alloy of a rare earth metal and a transition metal, is formed by sputtering,
It is preferably formed as an amorphous film by an evaporation method, an ion plating method, or the like.

As the rare earth metal, it is preferable to use one or more of Tb, Dy, Nd, Gd, Sm, and Ce.

 Fe and Co are preferable as the transition metal.

In this case, the total content of Fe and Co is preferably 65 to 85 at%.

 The balance is substantially a rare earth metal.

Preferred recording layer compositions include TbFeCo, Dy
There are TbFeCo, NdDyFeCo, NdGdFeCo and the like.

In the recording layer, Cr, Al, T
i, Pt, Si, Mo, Mn, V, Ni, Cu, Zn, Ge, Au and the like may be contained.

In addition, Sc, Y, La, Ce, Pr, P
Other rare earth metal elements such as m, Sm, Eu, Ho, Er, Tm, Yb, and Lu may be contained.

The layer thickness of such a recording layer 6 is usually about 10 to 1000 nm.

Depending on the method of forming the recording layer 6, for example, during sputtering, the disk may be placed at a temperature of about 60 to 100 ° C. However, since the resin layer 3 has high heat resistance,
Almost no deformation due to heat.

Therefore, a magneto-optical recording disk 1 having high mechanical accuracy can be obtained.

In other words, the effect of the present invention is remarkably exhibited particularly when the recording layer 6 is formed at a high temperature, for example, at a temperature of about 60 to 100 ° C., as in a vapor deposition method.

The protective coat 8 is provided for improving corrosion resistance and abrasion resistance, and is preferably made of various organic substances. It is preferable to be composed of a substance cured by radiation such as rays or ultraviolet rays.

The thickness of the protective coat 8 is usually about 0.1 to 100 μm.

Such a coating film may be usually formed by combining various known methods such as spinner coating, gravure coating, spray coating, and dipping.

The protection substrate 10 is provided as necessary to effectively prevent the recording layer 6 from being damaged, and is usually made of glass or resin.

The thickness of the protective substrate 10 is usually
It is about 0.5 to 2.0 μm.

The protective substrate 10 may be, for example, an adhesive layer 9 as illustrated.
And integrated with the substrate 2.

The adhesive to be used is not particularly limited, but a hot melt adhesive is preferred.

A hot-melt adhesive generally comprises a base polymer as a main component and additives such as a tackifier, a softener, a plasticizer, and a wax.

When bonding, for example, when using a hot-melt adhesive, a roll coater or the like may be used.

The thickness of the adhesive layer 9 is usually about 10 to 100 μm.

In the above, the case where the optical disk of the present invention is applied to a single-sided recording type magneto-optical recording disk has been described, but the present invention can also be applied to a double-sided recording type magneto-optical recording disk.

A double-sided recording type magneto-optical recording disk is obtained by preparing two substrates 2 having the above-described respective constituent layers and bonding the recording layer 6 with, for example, an adhesive layer 9 so that the recording layer 6 is enclosed.

In addition, the present invention can be applied to an optical recording disk having a so-called phase-change type recording layer and performing recording and reproduction by changing the reflectance.

As such a recording layer, for example, Japanese Patent Publication No. 54-4190
2, Te-Se alloys described in Patent No. 100004835, etc., Te-Ge alloys described in JP-A-62-76035, etc., and JP-A-63-5
No. 6827, etc., Te-In alloy, Japanese Patent Application No. 61-307298
No., Japanese Patent Application No. 61-307299, Te-Sn based alloys described in JP-A-58-54338, Patent No. 974257, Patent No. 974258,
Te oxides described in Patent No. 974257, etc., and other various T
e, Se-based chalcogen-based, Ge-Sn, Si-Sn, etc. alloys that produce an amorphous-crystalline transition Color change due to crystal structure change of Ag-Zn, Ag-Al-Cu, Cu-Al, etc. And alloys such as In-Sb that cause a change in crystal grain size.

Further, the present invention can also be applied to an optical recording disk having a so-called pit forming type recording layer in which a change in reflectance occurs due to pit formation.

Pit-forming recording layers include dyes such as cyanine-based, phthalocyanine-based, naphthalocyanine-based, anthraquinone-based, azo-based, triphenylmethane-based, pyrylium or thiapyrylium salt-based, and Te-based such as Te-based. Materials are used.

In addition, the present invention may be a read-only optical disk such as an optical video disk and an optical digital audio disk. However, preferably, of the above, a recording layer containing a metal on which a recording layer is formed by a vapor deposition method, particularly a phase-change optical recording disk having a metal recording layer, and a metal containing a rare earth metal element or the like. A magneto-optical recording disk having a recording layer, particularly a metal recording layer.

In the case of an optical disc having a recording layer containing such a metal, when forming the recording layer, the disc is placed at a high temperature, for example, at a temperature of about 60 to 100 ° C., so that the resin having high heat resistance is used. By forming the layer, deformation of the resin layer due to heat can be prevented, and an optical disc with high mechanical accuracy is realized.

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

[Example 1] A resin layer 3, a glass protective layer 4,
A SiNx intermediate layer 5, a TbFeCo recording layer 6, a SiNx protective layer 7, and a protective coat 8 are formed, and finally, a resin protective substrate 10 is adhered by an adhesive layer 9, and a single-sided recording light shown in FIG. A magnetic recording disk was manufactured.

The glass substrate 2 was made of alumina silicate-based chemically strengthened glass and had a disk shape with an outer diameter of 200 mm and a thickness of 1.2 mm.

The resin layer 3 was formed to a thickness of 30 μm by a 2P method, and a tracking groove was formed on the surface thereof.

In this case, the following were used as the ultraviolet curable monomer and the photopolymerization initiator.

UV curable monomer A1: Trimethylolpropane triacrylate UV curable monomer A2: neopentyl glycol diacrylate hydroxypivalate UV curable oligomer A3: Aronix M-8100 A: acrylic acid, X: polyhydric alcohol, Y: polybasic acid Photopolymerization initiator B1: 2,2-dimethoxy-2-phenylacetophenone Photopolymerization initiator B2: 2-methyl- [4- (methylthio) phenyl] -2-
Morpholino-1-propanone Samples No. 1 to No. 3 having different resin layers were produced by mixing the above A1, A2, A3, B1 and B2 at the compounding ratio (weight ratio) shown in Table 1.

A high-pressure mercury lamp was used for curing the resin, and the curing conditions were as follows.

UV irradiation amount: 1 Joule / cm ² Maximum radiant flux: 0.1 Watt / cm ² Atmosphere: In N ₂ gas Protective layer 4, intermediate layer 5, recording layer 6 and protective layer 7 were each formed by a sputtering method. .

Further, the protective coat 8 is formed by applying an oligoester acrylate and then irradiating ultraviolet rays to crosslink and cure.
The layer was set to 10 μm.

The adhesive layer 9 was formed by using a hot-melt adhesive and using a roll coater to have a thickness of 80 μm.

The elastic modulus and the mechanical loss coefficient tan δ at 20 ° C. and 100 ° C. of the resin layer 3 of each of the obtained samples are as shown in Table 1.

In this case, the elastic modulus and the mechanical loss coefficient tanδ were measured as follows.

Resin layer on release paper using roll coater, thickness 100 ~ 5
It was applied so as to have a thickness of 00 μm, and was cured under the same conditions as the sample. The obtained resin layer was peeled from the release paper, and measured at 0 to 150 ° C. at an excitation frequency (sine wave) of 10 Hz using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho.

Each of the obtained samples was placed in an atmosphere at a temperature of 80 ° C. and a humidity of 80% RH and stored for 500 hours.

After that, the optical disk mechanical characteristics measuring device ODA-I
Using I (manufactured by Shin Denshi Kogyo), the mechanical accuracy of each sample was measured.

The measurement conditions were as follows: disk rotation speed: 1800 rpm, laser power: 1 mW, inner circumference r = 55 mm to outer circumference r = 95 mm
Until then, the machine accuracy was measured every 5 mm.

As a result, it was confirmed that the comparative sample No. 3 had many tracking errors, had poor eccentric acceleration and roundness of the disk, and had low mechanical accuracy of the disk.

On the other hand, it was confirmed that the samples No. 1 and No. 2 of the present invention had low eccentric acceleration and the like and high mechanical accuracy of the disk.

The samples No. 1 and No. 2 according to the present invention correspond to the resin layer 3
It was easy to peel off the stamper and the resin when forming, that is, after curing with ultraviolet light.

Then, the master pattern of the stamper could be transferred accurately, and the shape of the formed groove could be maintained well.

 From these results, the effect of the present invention is clear.

Example 2 An optical recording disk sample of a phase change type that performs recording / reproduction by changing the reflectance was manufactured in the same manner as in Example 1 except that the recording layer 6 was changed to a Te—Sn—Ge alloy.

In this case, the recording layer 6 was formed by high-frequency magnetron sputtering.

When the same evaluation as in Example 1 was performed on each sample, equivalent results were obtained.

 The effects of the present invention are clear from the above results.

<Effect of the Invention> The resin layer of the optical disc of the present invention has high heat resistance, high moisture resistance, and high film strength.

For this reason, the resin layer is not deformed by heat even in the case where the recording layer and other layers are formed at a high temperature in the intermediate step of manufacturing the disk.

 And an optical disk with high mechanical accuracy is realized.

In addition, the mechanical accuracy of the disk can be kept high even when the disk is stored or used under high temperature and high humidity.

When a resin layer is formed on a substrate by the 2P method, the cured resin can be easily peeled off from the stamper.

In addition, the shape of the formed grooves and pits is favorably maintained, and a resin layer on which the master mold turn of the stamper is accurately transferred can be formed.

 For this reason, yield and mass productivity are improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the optical disk of the present invention. DESCRIPTION OF SYMBOLS 1 ... Magneto-optical recording disk 2 ... Substrate 3 ... Resin layer 4 ... Protective layer 5 ... Intermediate layer 6 ... Recording layer 7 ... Protective layer 8 ... Protective coat 9 ... Adhesive layer 10 ... Protective substrate

Claims (1)

(57) [Claims] A resin layer cured by irradiation with radiation on a substrate, wherein the resin layer has a modulus of elasticity at a frequency of 10 Hz and a temperature of 20 to 100 ° C. of 200 kgf / mm ² or more; An optical disc having a mechanical loss coefficient tan δ at a frequency of 10 Hz and a temperature of 20 to 100 ° C. of 0.01 to 0.2, and a metal recording layer formed on the resin layer.