JPS63239631A - Optical recording medium - Google Patents

Abstract

PURPOSE:To eliminate an undesirable influence of a heat at the time of adhering two substrates on a medium and to improve durability and moisture resistance by subjecting a coated film of an adhesive agent to radiation curing and anaerobic curing to form an adhesive agent layer and forming an org. protective coating layer to the hardness higher than the hardness of the adhesive agent layer. CONSTITUTION:A recording layer is provided on at least one of a pair of substrates except the inner and outer circumferential parts thereof and the org. protective coating layer is formed thereon. The substrates are integrated via the adhesive agent layer in such a manner that the recording layers are positioned on the inside. The adhesive agent layer is formed by subjecting the coated film of the adhesive agent having an acrylic or methacrylic group to radiation curing and anaerobic curing. Radiations are projected on the substrates to adhere the inner and outer circumferential parts of the substrates to each other, then the remaining parts are adhered by the anaerobic curing. The org. protective coating layer is formed by subjecting a coated film contg. a radiation curing type compd. to radiation curing and is formed to the hardness higher than the hardness of the adhesive agent layer. The exfoliation of the org. protective coating layer and the adhesive agent layer and the deterioration in the characteristics and appearance thereof are thereby obviated and the optical recording medium having the excellent durability and moisture resistance is obtd.

Description

Detailed Description of the Invention (1) Background of the Invention Technical Field The present invention relates to an optical recording medium such as a magneto-optical recording medium in which information is recorded and reproduced using heat and light such as a laser beam.

Prior art and its problems One type of optical recording medium is a magneto-optical memory medium.

As a recording medium for magneto-optical memory, MnB1. MnAJ! Ge, MnSb.

MnCuB1. GdFe%TbFe.

GdCo, PtCo, TbCo, TbFeCo, GdFeCo, TbFeO3, Gd1G, GdTbFe, GdTbFe
Materials such as Co81%CoFe2O4 are known.
These methods include vacuum evaporation, sputtering, etc.
It is formed as a thin film on a transparent substrate such as plastic or glass. Common characteristics of these magneto-optical recording media include the fact that the axis of easy magnetization is perpendicular to the film surface, and that the Kerr effect and Faraday effect are large.

As a recording method for a magneto-optical recording medium that takes advantage of this property, there are, for example, the following methods.

First, the entire film is magnetized to "0", that is, uniformly (this is called erasing). Next, a laser beam is irradiated onto the part where you want to record "1". The temperature of the area irradiated with the laser beam rises, and when it approaches the Curie point and further exceeds the Curie point, it approaches the coercive force Hc. Then, when the laser beam is turned off and the temperature is returned to room temperature, the magnetization is reversed due to the energy of the demagnetizing field. This is inverted and a signal of "1" is recorded.

Furthermore, since the initial state of recording is "0", "0" remains in the area where the laser beam is not irradiated.

Reading of a recorded magneto-optical memory can be performed in the same way using a laser beam, by rotating the plane of polarization of the reflected light due to the direction of magnetization of the laser beam irradiation light, that is, by utilizing the magneto-optical effect.

First, such a medium is required to have a Curi point of about 100 to 200° C. and a compensation point of around room temperature.

Second, there are relatively few defects such as grain boundaries that cause noise.

Thirdly, a magnetically and mechanically uniform film can be obtained over a relatively large area without using methods such as high-temperature film formation or long-time film formation.

In response to such demands, among the above-mentioned materials, amorphous perpendicular magnetic thin films of rare earth-transition metals have recently attracted much attention.

However, when magneto-optical recording media made of such rare earth-transition metal amorphous thin films are stored in contact with the atmosphere,
The rare earth elements are selectively corroded or oxidized by oxygen or water in the atmosphere that enters through the substrate, making it impossible to record or reproduce information.

Therefore, many studies have generally been conducted on devices having a structure in which a protective layer is provided between the magnetic thin film layer and the substrate and/or on the magnetic thin film layer.

Conventionally, as such a moisture-proof protective layer, an attempt has been made to provide a vacuum-deposited film of an inorganic material such as -silicon oxide or silicon dioxide (Japanese Patent Application Laid-Open No. 80142/1983).

Among these protective layers, an inorganic protective layer such as 5iO1 is formed by sputtering, vapor deposition, or the like.

However, depending on these methods, it is difficult to form a uniform, dense, and uniformly covered film, and a protective layer with partial moisture resistance cannot be obtained. Therefore, aging deterioration of the magnetic thin film layer of the magneto-optical recording medium cannot be improved.

Furthermore, even a protective layer coated with a resin that hardens at room temperature does not provide sufficient moisture resistance, and during storage, moisture and oxygen permeate, which promotes deterioration.

In addition, an organic protective coating layer has been proposed in which a coating film of a radiation-curable compound is cured by ultraviolet rays (Japanese Unexamined Patent Publication No. 6
No. 1-133067) discloses a cured coating film containing oligoester acrylate and methyl benzoyl and formate (Bicure 55, manufactured by Stouffer Japan) as a photosensitizer.

However, these are insufficient in terms of protective layer function and curability.

Specifically, problems include a slow curing speed, insufficient strength of the cured film when formed into a thin film, and the need to increase the film thickness. These problems are mainly caused by the fact that the photoinitiator or photosensitizer does not have sufficient light absorption, making it difficult for radical cleavage to proceed.

Furthermore, if curing is insufficient, the crosslinking density will be low, and uncured monomers and oligomers will permeate into the recording layer, causing adverse E'ff effects on the recording layer. This phenomenon becomes especially noticeable when stored at high temperature and high humidity.

Therefore, optical recording media using such a cured film cannot be said to have sufficient reliability.

By the way, optical recording media are usually integrated with a protective plate in the case of a single-sided recording type, and substrates in the case of a double-sided recording type through an adhesive layer.

The adhesive used in these cases is generally a hot melt adhesive or a thermosetting adhesive.

However, hot-melt adhesives reach high temperatures of over 100°C during bonding, which not only adversely affects the recording layer and substrate, but also
There are drawbacks such as warping of the medium after adhesion.

Furthermore, thermosetting adhesives still require a high temperature of 100° C. or higher for rapid bonding, and have the same drawbacks as the hot melt adhesives described above.

In order to eliminate these drawbacks, transparent areas without recording layers are provided on the inner and outer peripheries of the substrates, and such substrates are bonded together using an adhesive that has both ultraviolet curing and anaerobic curing functions. An information recording disk has been proposed in which the two are joined together (Japanese Unexamined Patent Publication No. 61-217944).

In this method, the substrates are stacked on top of each other, first irradiated with ultraviolet rays to bond the inner and outer circumferential portions, and then left to naturally harden anaerobically to bond the remaining portions. No heat is applied to the substrates, and no displacement occurs between the substrates during anaerobic curing.

However, when bonding substrates together using such an adhesive, if an organic protective coating layer as described above is provided on the recording layer, that is, if the adhesive layer and the organic protective coating layer are in contact with each other. If the media after adhesion is stored under conditions of high temperature, high humidity, or changes in temperature and humidity, peeling occurs between the adhesive layer and the organic protective coating layer, making it impossible to obtain a highly durable media. .

Incidentally, such a problem also occurs in an optical recording medium having a so-called phase transition type recording layer.

■Object of the Invention The object of the present invention is to have a pair of substrates, a recording layer on at least one of the substrates, and an organic protective coating layer on the recording layer. In optical recording media that are integrated via an adhesive layer so that the inner substrate is on the inside, there is no adverse effect on the medium due to heat when adhering the inner substrate, and the adhesion is quick and there is no displacement between the substrates after adhesion. Provides an optical recording medium with excellent durability and moisture resistance, with no warping of the substrate, and no peeling of the organic protective coating layer and adhesive layer even when stored under conditions of high temperature, high humidity, or changes in temperature and humidity. It's about doing.

■Disclosure of invention Such objects are achieved by the present invention as described below.

That is, the present invention has a pair of substrates, has a recording layer on at least one of the substrates except for the inner and outer peripheral portions of the substrate, has an organic protective coating layer on the recording layer, and In an optical recording medium in which two substrates are integrated via an adhesive layer so that the recording layer is on the inside, the organic protective coating layer is made by radiation-curing a coating film containing a radiation-curable compound. , the adhesive layer is obtained by radiation curing and anaerobic curing of an adhesive coating containing a compound having an acrylic or methacrylic group,
The optical recording medium is characterized in that the hardness of the organic protective coating layer is greater than the hardness of the adhesive layer.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The optical recording medium of the present invention includes a pair of substrates, has a recording layer on at least one of the substrates except for the inner and outer peripheral portions of the substrate, and has an organic protective coating layer on the recording layer. , these pair of substrates are integrated via an adhesive layer so that the recording layer is on the inside.

The organic protective coating layer is obtained by radiation curing a coating film containing a radiation-curable compound, and the adhesive layer is a coating film of an adhesive containing a compound having an acrylic or methacrylic group, which is cured by radiation curing and anaerobic curing. This is what I did.

Further, the hardness of the organic protective coat layer is configured to be higher than the hardness of the adhesive layer.

With this structure, the organic protective coating layer and the adhesive layer do not peel off even when stored under high temperature, high humidity, or changing conditions of temperature and humidity.

The hardness of such an organic protective coating layer is preferably about H to 3H in terms of pencil hardness (JIS K-5400) at 25°C. If it is softer than 3H, the durability will be insufficient, and if it is harder than 3H, the coating film will become brittle and the film forming ability will decrease, as well as the adhesion to the substrate and the sputtered film such as the recording layer will decrease.

Further, the hardness of the adhesive layer is preferably about 28 to H in terms of pencil hardness. If it is softer than 2B, the durability will be insufficient.
When the hardness is higher than H, the ability to alleviate disk distortion such as substrate warpage decreases.

The hardness of the organic protective coat layer and the adhesive layer is within such ranges and has the above-mentioned relationship.

Note that when the organic protective coating layer and the adhesive layer are applied using, for example, a spin cord, there may be a difference in film thickness between the inner and outer peripheral parts, and this difference in film thickness may cause a difference in hardness. be. Even in such a case, it is necessary in the present invention that both layers have the above-mentioned hardness in the entire area.

The radiation-curable compound used to form such an organic protective coat layer preferably contains oligoester acrylate.

Oligoester acrylate is an oligoester compound having multiple acrylate groups or methacrylate groups. The preferred oligoster acrylate has a molecular weight of 1,000 to 10,000, preferably 200
0 to 7000, and the degree of polymerization is 2 to 10, preferably
3 to 5 are listed. Among these, polyfunctional oligoester acrylates having 2 to 6, preferably 3 to 6 acrylate groups or methacrylate groups are preferred.

7 as polyfunctional oligoester acrylate: -
tx M-7100, M-5400, M-5500, M
-5700, M-6250, M-6500, M-803
0, M-8060, M-8100, etc. (manufactured by Toagosei Kagaku Co., Ltd.) can be used, and these are represented by the following formulas (A) and (B).

(A) (B) A-%M-N+, -M-A A near acrylate group or methacrylate group, M: dihydric alcohol (e.g., ethylene glycol, diethylene glycol, 1,6-hexane glycol, bisphenol A, etc.) residue group, N: dibasic acid (e.g. terephthalic acid, isophthalic acid,
adipic acid, succinic acid, etc.) residue, n: 1 to 10, preferably 2 to 5. Among these, those represented by (A) are preferred.

Such oligoester acrylates may be used alone.

Further, other radiation-curable compounds may be used in combination. In such a case, it is preferable that the oligoester acrylate is present in the radiation curable compound in an amount of 20% or more.

The above oligoester acrylate can be used in combination with other radiation-curable compounds, such as acrylic acid, methacrylic acid, which has an unsaturated double bond that is sensitive to ionization energy and exhibits radical polymerizability. Acrylic double bonds such as acids or their ester compounds, allylic double bonds such as diallyl phthalate, unsaturated double bonds such as maleic acid and maleic acid derivatives, and groups that can be crosslinked or polymerized by radiation irradiation. Examples include polymers, oligomers, and polymers containing or introducing into the molecule. These are preferably polyfunctional, particularly trifunctional or more functional.

As a radiation-curable monomer, a compound with a molecular weight of less than 2,000 is used, and as an oligomer, a compound with a molecular weight of 12,000 to 100 is used.
00 is used.

These include styrene, ethyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol methacrylate, 1,6-hexane glycol diacrylate, 1,6-hexane glycol diacrylate, etc., but particularly preferred ones are Examples include pentaerythritol tetraacrylate (methacrylate), pentaerythritol acrylate (methacrylate), trimethylolpropane triacrylate (methacrylate), trimethylolpropane diacrylate (methacrylate), acrylic modified products of urethane elastomer and tuberane 4040), or these. Products into which functional groups such as C0OH have been introduced, acrylates (methacrylates) of phenol ethylene oxide adducts, and pentaerythritol condensed ring represented by the following general formula with an acrylic group (methacrylic group) or ε-caprolactone-acrylic group attached. Compound, 1) (CH2=C)ICOOCH2)3-CCH2
0) 1 (Special acrylate A) 2) (CH2=CHCOOCH2) 3-CC82
0H3 (special acrylate B) 3) (CH2=CH0C(OC3H6)n -0
CH2)3-CCH2C)13 (Special acrylate C) (Special acrylate D) (Special acrylate E) CH2CH2C00CH=CH2 (Special acrylate F) In the formula, a compound where m=1, a=2, b=4 (hereinafter referred to as special pentaerythritol condensate A), m=1, a=3, b=3 (hereinafter referred to as special pentaerythritol condensate B), m=1. a=6, b=
o compound (hereinafter referred to as special pentaerythritol condensate C
), m = 2, a = 6, b = o (hereinafter referred to as special pentaerythritol condensate), and special acrylates represented by the following general formula.

8) CH2=CHCOO-(CH2CH20)4-
COCH=CH2 (special acrylate H) CH,2CH2C00CH=CH2 (special acrylate ■) (special acrylate J) In addition, radiation-curable oligomers include acrylic modified products of urethane elastomers, or C
Examples include those into which a functional group such as 0OH is introduced.

Further, in addition to or in place of the above-mentioned compounds, a radiation-curable compound obtained by radiation-sensitizing a thermoplastic resin may be used.

Specific examples of such radiation-curable resins include acrylic acid, methacrylic acid, or acrylic double bonds such as ester compounds thereof, which have unsaturated double bonds exhibiting radical polymerizability, and diallylphthalate. It is a thermoplastic resin in which groups that can be crosslinked or polymerized by radiation irradiation, such as allylic double bonds and unsaturated bonds such as maleic acid and maleic acid derivatives, are contained or introduced into the molecule of the thermoplastic resin.

Examples of thermoplastic resins that can be modified into radiation-curable resins include vinyl chloride copolymers, saturated polyvinyl sulfate resins,
Examples include polyvinyl alcohol resins, epoxy resins, phenoxy resins, cellulose derivatives, and the like.

Other resins that can be used for radiation sensitivity modification include polyfunctional polyester resins, polyether ester resins, polyvinyl pyrodone resins, and derivatives (pvp
Also effective are acrylic resins containing at least one of olefin copolymers), polyamide resins, polyimide resins, phenol resins, spiroacetal resins, hydroxyl group-containing acrylic esters, and methacrylic esters as polymerization components.

The thickness of the organic protective coating layer of such a radiation-curable compound is 0.1 to 30 μm, more preferably 1 to 10 μm.

If the film thickness is less than 0.1 μm, it will not be possible to form a uniform film, and the moisture-proofing effect will not be sufficient in a humid atmosphere.
The durability of the recording layer does not improve. If the thickness exceeds 30 μm, the recording medium may warp or cracks may occur in the protective film due to shrinkage during curing of the resin film, making it unsuitable for practical use.

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

In the present invention, examples of the radiation irradiated onto the coating film include ultraviolet rays, electron beams, etc., but ultraviolet rays are preferred.

When ultraviolet rays are used, a photopolymerizable sensitizer is usually added to the radiation-curable compound as described above.

The photopolymerization sensitizer used in the present invention has the following general formula (1
) are preferred.

By using this material with polyfunctional oligoester acrylate, the above-mentioned hardness can be easily obtained and the film properties can also be improved. Peeling from the adhesive layer is also reduced, and durability and moisture resistance are also improved.

General Formula (I) In the above general formula (I), R represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group, etc., especially a methyl group, Ethyl group etc. are preferred.

L is a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms, such as -CH2+.

CH3 etc., especially CH3 ■ C- Lu CH3 is preferred.

Y is a heterocyclic group, such as a morpholino group, a 2-morpholinyl group, a piperidino group, a 4-piperidinyl group, a 2-pyridyl group, a 2-quinolyl group, a 1-pyrrolidinyl group, a 1-pyrrolyl group, a 2-chenyl group, 2-furyl group, etc.
Among these, a morpholino group is preferred.

RS- may be bonded to the benzene ring at any substitutable position of the benzene ring in general formula (I), but is preferably the 2-position of C-L-Y.

In the present invention, among the compounds represented by general formula (I), the following are most preferred.

Compound A This compound A is commercially available as IRGACURE907 (manufactured by Ciba Geigy, Japan).

The compound represented by the general formula (I) acts as a photopolymerization initiator or photopolymerization sensitizer during radiation curing.

The content of such a compound in the organic protective coating layer is preferably 0.1 to 20 wt%, preferably 1 to 10 wt%.

This is because the effect as a photopolymerization initiator or photopolymerization sensitizer is insufficient if the amount is less than 0.0%, and 20% by weight.
This is because if the temperature is exceeded, the remaining photopolymerization initiator or photopolymerization sensitizer will penetrate into the recording layer and give an adverse effect on the recording layer.

Further, as the photopolymerization sensitizer, in addition to the compound represented by the above-mentioned general formula (I), the following known ones can be used in combination, if necessary.

For example, benzoin series such as benzoin methyl ether, benzoin ethyl ether, α-methylbenzoin, and α-chlordeoxybenzoin, ketones such as benzophenone, acetophenone, and bisdialkylaminobenzophenone, quinones such as acedraquinone and phenanthraquinone, and benzyl disulfide. and sulfides such as tetramethylthiuram monosulfide.

In order to cure a coating film containing such a photopolymerizable sensitizer and a radiation-curable compound using ultraviolet rays, various known methods may be used.

For example, an ultraviolet light bulb such as a xenon discharge tube or a hydrogen discharge tube may be used.

Moreover, an electron beam can also be used depending on the case.

Next, the adhesive layer will be explained.

The adhesive layer of the present invention is obtained by radiation curing and anaerobic curing of a coating of an adhesive containing a compound having an acrylic or methacrylic group, as described above.

As the compound containing a (meth)acrylic group, oligoester acrylate is preferred.

As the oligoester acrylate, those similar to those mentioned above in the explanation of the organic protective coat layer are preferred.

Oligoester acrylate may be used alone,
It may be used in combination with another radiation-curable compound having a (meth)acrylic group or a radiation-curable compound not having an acrylic group. When used in combination with other actiniocurable compounds,
It is preferable that the oligoester acrylate is present in the radiation curable compound in an amount of 50 I% or more, preferably 70 I% or more.

As other radiation-curable compounds, the same compounds as those mentioned above in the description of the organic protective coat layer can be used.

However, the monomers mentioned above tend to remain uncured;
This may have an adverse effect on the recording layer, etc., so
It is preferable to keep the amount added as low as possible.

Examples of radiation used to cure such radiation-curable compounds include ultraviolet rays; electron beams, etc.
Preferably, ultraviolet light is used.

As the ultraviolet light source, for example, an ultraviolet light bulb such as a xenon discharge tube or a hydrogen discharge tube may be used.

When using ultraviolet light, a photopolymerizable sensitizer is usually added to the adhesive. As the photopolymerization sensitizer, compounds such as those mentioned above in the explanation of the organic protective coating layer are preferred.

In addition to the above-mentioned radiation-curable compound and photopolymerization sensitizer, the adhesive preferably contains a component containing an oxidizing agent and a component containing a reducing agent, and the reaction of these components generates initiating species. It is preferable that the above compound having a (meth)acrylic group be anaerobically cured.

The adhesive used in the present invention is usually a so-called two-component anaerobic curing adhesive, that is, a component containing an oxidizing agent and a component containing a reducing agent are separated, and at least one of them has ( Preferably, the adhesive contains a compound having a meth)acrylic group, and these two components are mixed and used when applying the adhesive.

As the oxidizing agent used, diacyl peroxides and dialkyl peroxides are useful, and specific examples thereof include benzoyl peroxide.

In addition, as reducing agents, tertiary amines and mercaptan compounds are useful, and specific examples thereof include N,
Examples include N-dimethylaniline.

The ratio of the oxidizing agent and reducing agent to the above-mentioned radiation-curable compound is preferably about 0.1 to 10 mol% of the oxidizing agent and reducing agent to the radiation-curable compound.

If this value is less than 0.1 mofi%, the redox reaction will be difficult to occur, the starting species will be difficult to generate, and 10 mofi% will be less likely to occur.
%, unreacted reagents may cause adverse effects on the recording layer,
Pot life becomes shorter.

Such an adhesive may be applied by various known methods as described above in the description of the organic protective coating layer.

Further, the thickness of the adhesive layer obtained by radiation-curing and anaerobically-curing such an adhesive is preferably 5 to 50 μm. If the thickness is less than 5 μm, adhesiveness will be poor, and if it exceeds 50 μm, durability will be reduced.

The substrate used in the optical recording medium of the present invention is made of resin, various types of glass, or the like.

Preferred resins include acrylic resin, polycarbonate resin, epoxy resin, polymethylpentene resin, and the like.

Note that since recording is performed through the substrate, the transmittance for writing light or reading light is set to 86% or more.

In addition, the board is usually disk-shaped and has a length of 1.2 to 1.5 m.
The thickness should be about m.

Tracking grooves or pits may be formed on the recording layer forming surface of such a disc-shaped substrate.

The depth of the groove is about λ/8n, especially λ/6n~λ
/ 12 n (where n is the refractive index of the substrate). Further, the width of the groove is approximately the width of a track.

In general, it is preferable to use the recording layer located in the four parts of the groove as a recording track part, and to irradiate the writing light and the reading light from the back side of the substrate.

With this configuration, the writing sensitivity and the reading C/N ratio are improved, and the tracking control signal is also increased.

In addition, other shapes of the substrate may be used, such as a tape or a drum.

The recording layer used in the present invention includes a magnetic thin film layer.

Information is magnetically recorded in the magnetic thin film layer using a modulated heat beam or a modulated magnetic field, and the recorded information is reproduced by magneto-optical conversion.

The material for such a magnetic thin film layer is an amorphous film formed by sputtering, vapor deposition, etc. of an alloy of rare earth metals such as Gd and Tb and transition metals such as Fe and Co. It contains Co as an essential component.

In this case, the total content of Fe and Co is 65 to 85 at%
It is preferable that

The remainder is substantially rare earth metals, especially Gd and/or
Or Tb.

Suitable examples include TbFeCo, GdFe
Co, GdTbFeCo, etc.

Note that these magnetic thin film layers contain Cr, A!, in a range of 10 at% or less. L, Ti, Pt, Si, Mo, Mn, ■, N
i%Cu% Zn, Ge, Au, etc. may be contained.

In addition, as a rare F-class element, Sc% within a range of 10aL% or less
Y, La, Ce%Pr, Nd%Pm.

Sm, Eu, Dy%Ho, Er, Tm, Yb.

It may also contain Lu or the like.

The thickness of such a magnetic FF film layer is preferably 0.01 to 1-.

Other materials for the recording layer include so-called phase transition type materials, such as Te-5s%Te-3e-Sn, Te-Ge, and Te-In%Te-5n.

Te-Ge-5b-3, Te-Ge-As-5n%Te-5i, Te-Ge-5
1-3b.

Te-Ge-B1, Te-Ge-In-Ga.

Te-5i-B 1-Tll, Te-Ge-B1-In-5, T e - A s - G'e - S b.

Te-Ge-5s-S.

Te-Ge-3e.

Te-As-Ge-Ga, Te-Ge-3-I n.

S e -G e -T 11 , 5e-Te-
As, 5e-Ge-T JZ-Sb, 5e-Ge-Bi, 5e-5 (all of the above, Special Publication No. 54-41
902, Patent No. 1004835, etc.) Tea, (Japanese Unexamined Patent Publication No. 58-54338, Patent No. 9742)
Teo, l + Pb0 -Zn-5
b, Te-5e-Ga, Te, Se, etc.
Alloys that cause an amorphous-crystalline transition such as chalcogen-based Ge-5n, 5i-3n, etc. mainly composed of A g-Zn, A g-An-Cu, Cu
There are alloys that cause a color change due to a change in crystal structure, such as -Aft, and alloys that cause a change in crystal grain size, such as In-3b.

In the present invention, such a recording layer and the protective layer, intermediate layer, etc. provided as necessary are provided on the substrate except for the inner and outer peripheral portions.

By forming the layers in this way, the radiation curing of the adhesive layer described above can be carried out easily and reliably when bonding the same substrates.

In the present invention, an intermediate layer may be provided between the substrate and the i11 layer.

The material of the intermediate layer may be a compound containing oxygen, carbon, nitrogen, sulfur, etc., such as 5in2, Sio, AJIN, A
1203, S i3 N,, ZnS, BN%Tie2
, TiN, etc., or mixtures thereof, such as borosilicate glass, barium borosilicate glass, aluminum borosilicate glass, etc., or those containing Si3N, etc. may be used.

Among them, borosilicate glass of 5in240-80wt%, barium borosilicate glass, aluminum borosilicate glass, and some of these SiO2 are converted into St, N
Those substituted with 4 or the like are preferred.

Among these, the following are particularly preferred.

(1) Silicon oxide 40-60 wL%, Bad, Cab
, SrO, MgO, ZnO.

Contains 50 wL% or less of a divalent metal oxide such as pbo and/or 10 wt% or less of an alkali metal oxide, and boron oxide and/or aluminum oxide.

(2) Si and other metal or metalloid elements such as Ba and C
one or more of a, Sr, Mg, Zn, Pb, etc., AiL, H
and at least one of one or more alkali metal elements, and Si in all metals or metalloids
Those whose atomic ratio is 0.3 to 0.9, roughly contain O and N, and whose O/(0+N) is 0.4 to 0.8.

Such an intermediate layer may have a thickness of 500 to 3000 people, preferably 800 to 2500 people.

If it is less than 500λ, the weather resistance will not be sufficient, and if it exceeds 1,500 people, it will be too thick and the sensitivity will decrease when used as a medium.

In addition, as for these intermediate layers, about 300 to 1000 layers are formed using the above-mentioned glass layer as the intermediate layer base, and on top of this, SiO,,5iO1S i3 N 4 , A JZ
N, AJ', 203, ZnS, etc., or a mixture thereof, etc., are used as a dielectric layer.
It is preferable that the number of layers is 0 to 1,500.

In this case, the dielectric layer has a refractive index of 1.8 at 800 nm.
~3.0 is preferable, and Si and rare earth metals and/or
or A1, and preferably contains 0 and N.

A layer made of the same material as such an intermediate layer may be provided as a protective intermediate layer between the recording layer and the above-mentioned protective layer. The thickness may also be about the same.

The optical recording medium of the present invention further comprises one set of substrates having a recording layer, an organic protective coating layer, etc. as described above, which are placed facing each other with the image recording layer inside, and bonded together using the adhesive layer described above. In addition, it is possible to use a so-called double-sided recording type in which writing is performed from the back sides of both substrates.

The present invention is also applicable to a so-called single-sided recording type in which a recording layer is provided only on one substrate.

The resin material of the substrate on which the recording layer is not provided is not particularly required to be transparent, and various resins such as polyethylene, polyvinyl chloride, polystyrene, polypropylene, polyvinyl alcohol, methacrylic resin, polyamide, and polyester are used. Various thermoplastic resins such as vinylidene chloride, polycarbonate, polyacetal, and fluorine resins, as well as various thermoplastic resins such as phenolic resins, area resins, unsaturated polyester resins, polyurethane, alkyd resins, melamine resins, epoxy resins, and silicone resins, etc. can be used. It is.

Note that various inorganic materials such as glass and ceramics may be used.

The shape, dimensions, etc. of this material are approximately the same as those of the substrate provided with the recording layer.

Furthermore, it is preferable to provide a hard coat layer as various protective films on the back surface of these substrates (the surface on which the recording layer is not provided).

The material for the hard coat layer may be the same as the material for the organic protective coat layer described above.

■Specific Effects of the Invention The optical recording medium of the present invention has a pair of substrates, and has a recording layer on at least one of the substrates except for the inner and outer peripheries of the substrate, and on this recording layer. It has an organic protective coating layer, and these pair of substrates are integrated via an adhesive layer so that the recording layer is on the inside.

The adhesive layer described above is a coating film of an adhesive having an acrylic or methacrylic group that is cured by radiation and anaerobically, so when integrating both substrates,
First, the inner and outer peripheral portions of the substrate can be bonded together by irradiation with radiation such as ultraviolet rays, and then the remaining portions can be bonded by anaerobic curing. Therefore, no heat is applied to the medium during adhesion, and there is no adverse effect on the recording layer or substrate. Further, warpage of the substrate does not occur after bonding. Furthermore, the bonding is quick and there is no misalignment of the substrates during bonding, and in the end, the entire surface of the substrates is firmly bonded.

Further, the organic protective coat layer is formed by radiation-curing a coating film containing a radiation-curable compound, and is configured such that the hardness of the organic protective coat layer is greater than the hardness of the adhesive layer. Therefore, even when stored under conditions of high temperature, high humidity, or changes in temperature and humidity, there is no peeling between the organic protective coating layer and the adhesive layer, and there is no change in characteristics or appearance, resulting in optical recording with excellent durability and moisture resistance. The medium makes it happen.

(2) Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown and the present invention will be explained in more detail.

[Example 1] Glass (SiO□ 48wL%, Al12031 5wL%) was placed on a substrate made of bisphenol A polycarbonate resin (minute tm 15000) with a diameter of 13cm and a thickness of 1.2mm.
, B2O314wL%, Na2O3wj%, 202w
t%, Ba05wt%.

G! A total of 900 people were set up.

On this intermediate layer, 21aL%Tb, 68at%Fe, 7
A thin film of at% Co and 4 at% Cr alloy was deposited to a thickness of 800 mm by sputtering to form a magnetic thin film layer.
Note that the magnetic thin film layer was formed on the substrate except for the inner and outer peripheral portions. The target used was an Fe target with Tb, Co, and Cr chips mounted on it.

On this magnetic thin film layer, a protective intermediate layer of glass (same as the intermediate layer) was formed by sputtering to a thickness of 1000 mm.
On this protective intermediate layer, a coating composition containing the following radiation-curable compound and photopolymerizable sensitizer was applied as an organic protective coating layer by spinner coating.

(Coating composition) Multifunctional oligoester acrylate [oligoester acrylate (trifunctional or higher) 30% by weight, trimethylpropane acrylate 70% by weight, trade name Aronix M-
8030, manufactured by Toagosei Co., Ltd.] 100 parts by weight of photopolymerization sensitizer (Compound A: trade name IRGACURE907; manufactured by Ciba Geigy, Japan)
After applying 5 parts by weight of such a coating composition, it was irradiated with ultraviolet rays of 12,017 cm for 15 seconds to crosslink and cure to form a cured film.

The film thickness at this time was 5 μm.

On this organic protective coating layer, the following two types of adhesives containing an acrylic group-containing compound and a photopolymerization sensitizer are added, one containing an oxidizing agent and the other containing a reducing agent. After mixing equal amounts, they were applied using a spinner coat, and a protective plate made of the same material and size as the above substrate was laminated thereon. Then, radiation curing and anaerobic curing were performed under the following conditions.

Adhesive (oligoester acrylate type) Arontite LA-7 Arontite LB-8 (both Toagosei type) Curing conditions Radiation curing: Irradiation of 120 W/am ultraviolet rays for 15 seconds Anaerobic curing: Leave at room temperature for 10 minutes. The thickness of the formed adhesive layer is 30 μm
Met.

A single-sided recording type optical recording medium was obtained in the above manner, and this was designated as sample No. 1.

The polyfunctional oligoester acrylate used for the organic protective coating layer of sample No. 1 was mixed with Aroex M-400.
(6 functional or higher functional monomer) 50 parts by weight and Aloex M
Sample N
002 was produced.

In addition, the polyfunctional oligoester acrylate was replaced with 50 parts by weight of Aloex M-6100 (bifunctional oligoester acrylate) and 50 parts by weight of Aloex M-111 (monofunctional oligoester acrylate), and the others were Sample No. 1. Sample No. 3 was prepared in the same manner as above.

In addition, a one-component epoxy resin-based Arashidar 1'T A
Sample No. 014 was prepared in the same manner as Sample No. 1, except that T-1 (manufactured by Nippon Ciba Geigy) was spinner coated to a thickness of 5 μm to form an organic protective coating layer.

Furthermore, sample No. 1 oligoester acrylate was replaced with urethane acrylate (Aloex M-1
100) Change to 100 parts by weight, and the rest are sample No.
Sample No. 5 was prepared in the same manner as in Example 1.

In addition, in sample No. 1, the photopolymerization sensitizer was added to BI
Sample No. except that 5 parts by weight of QURE-55 (manufactured by Stouffer Japan) was used.

Sample No. 6 was prepared in the same manner as in Example 1.

The following tests were conducted on these samples.

Storage Test The medium was stored at high temperature and high humidity (80° C., 80% RH), and the characteristics of the medium (C/N ratio and pit error rate) and changes in appearance were observed.

The results are shown in Table 1.

The pencil hardness at 25° C. of the organic protective coat layer and adhesive layer of each sample was as shown in Table 1.

Further, the pencil hardness of the organic protective coat layer of sample No. 6 was HB at the inner circumference of the organic protective coat layer and H at the outer circumference.

From the above results, the effects of the present invention are clear.

Note that such an effect is caused by the so-called phase transition type Te-G.
This was similarly achieved with recording layers such as e, Teax, and Te-5e.

Applicant TDC Co., Ltd. Lecture

Claims (4)

[Claims] (1) A pair of substrates, a recording layer on at least one of the substrates except for the inner and outer peripheries of the substrate, an organic protective coating layer on the recording layer, and However, in optical recording media that are integrated with the recording layer on the inside via an adhesive layer, the organic protective coating layer is made by radiation-curing a coating film containing a radiation-curable compound, and the adhesive layer is The adhesive layer is obtained by radiation curing and anaerobic curing of an adhesive coating containing a compound having an acrylic or methacrylic group,
An optical recording medium characterized in that the hardness of the organic protective coating layer is greater than the hardness of the adhesive layer. (2) The hardness of the organic protective coat layer and adhesive layer is 25
The optical recording medium according to claim 1, which has a pencil hardness (JISK-5400) of H to 3H and 2B to H, respectively. (3) The optical recording medium according to claim 1 or 2, wherein the radiation-curable compound contains an oligoester acrylate. (4) The adhesive has a component containing an oxidizing agent and a component containing a reducing agent, and the reaction between these generates an initiating species, and the compound having an acrylic group or a methacrylic group is anaerobically cured. An optical recording medium according to any one of claims 1 to 3.