JPH10176018A - Ultraviolet curing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition containing a specific oligomer, having strong adhesivity to aluminum, polycarbonate, gold, silicon nitride, etc., and emitting practically negligible sulfur smell. SOLUTION: This composition contains a (meth)acrylic oligomer containing a polysulfide skeleton in the molecule. The oligomer is preferably composed of an epoxy resin having a polysulfide skeleton and acrylic acid. An optical disk composed of two information-recorded disks laminated to at least one disk is produced by using the composition. Preferably, both of the two disks have information recorded layers, one disk is a polycarbonate substrate having an aluminum thin film and the other disk is a polycarbonate substrate having a thin film of gold, silicon nitride or silicon carbide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet-curable composition for an optical disk, and more particularly, to an adhesive suitable for use in bonding two disks having an information recording layer to at least one disk. The present invention relates to an ultraviolet-curable composition.

[0002]

2. Description of the Related Art A digital video disk (DVD), which is a high-density information recording medium, is manufactured by bonding two disks having an information recording layer to at least one disk and bonding an ultraviolet-curable composition to the disk. Its use as an agent has been actively studied.

[0003] In the case of a read-only DVD, two discs to be bonded are each provided with irregularities corresponding to recorded information on one surface of a polycarbonate substrate, and further, for example, an aluminum layer is formed as a metal thin film. Or one using a translucent thin film such as gold or silicon nitride, or one using a transparent polycarbonate substrate without an information recording layer. Yes, the substrate is appropriately selected according to the application.

[0004] The three types of DVDs are, in order, a DV.
D-10 (both sides of reproduction surface-one signal layer each), DVD-9
(Single-sided playback surface-two signal layers) and DVD-5 (one-sided playback surface-one signal layer). In addition, there is also a format of DVD-17 (both layers on both sides of the reproduction surface and two signal layers).

[0005] For example, when an ultraviolet curable composition conventionally used for protecting an aluminum reflective film of a compact disk is used as an adhesive, it has a sufficient adhesive force to an aluminum thin film or a polycarbonate substrate, but has a sufficient adhesive strength. When silicon nitride or the like is used as a thin film, the adhesion to them is insufficient.
As an adhesive for use, an ultraviolet curable composition having a strong adhesive force to a substance forming a translucent film such as gold or silicon nitride other than aluminum or polycarbonate is required.

JP-A-7-320299 discloses a thioether-containing photopolymerizable compound as a compound having excellent adhesion to gold, but the thioether-containing photopolymerizable compound has a characteristic odor, and Even if a small amount is contained, the workability is extremely deteriorated due to the odor of the compound, and the same odor remains even in a cured product, which is practically practical.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a cured film having a strong adhesive force not only to aluminum and polycarbonate but also to gold and silicon nitride is provided. An object of the present invention is to provide an ultraviolet curable composition obtained.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by using an ultraviolet-curable composition containing a specific oligomer, aluminum, polycarbonate, gold, or chip. A strong adhesive force was obtained for silicon oxide and the like, and a sulfur-containing odor-free sulfur odor-deficient level was found.

That is, the present invention is directed to an optical disc having a film selected from the group consisting of gold, silicon nitride and silicon carbide, which comprises a (meth) acrylic oligomer containing a polysulfide skeleton in the molecule. An ultraviolet-curable composition is provided.

In the present invention, when (meth) is prefixed, as in (meth) acrylate, both methacrylate and simple acrylate are included. The specific oligomer used in the present invention has a molecular weight of 4
Those having a value of 00 or more are preferable. The (meth) acrylic oligomer refers to an oligomer having a (meth) acryloyl group. In addition, poly such as poly (meth) acrylate means 2 or more.

The (meth) acrylic oligomer having a polysulfide skeleton in the molecule in the present invention is used as an ultraviolet curable compound.

The polysulfide skeleton is represented by -SS-
Is a skeleton that requires a structure in which two sulfur atoms are directly connected, and is distinguished from a thioether skeleton consisting of only one sulfur atom, —S—. In the present invention, these differences in the number of sulfur atoms affect the magnitude of the odor.

The specific (meth) acrylic oligomer used in the present invention can be obtained, for example, by reacting an epoxy resin having a polysulfide skeleton with (meth) acrylic acid. Epoxy resins having such a polysulfide skeleton include, for example, FLEP-10, FLEP-
50, FLEP-60, FLEP-80 and the like are commercially available from Toraythiol Co., Ltd.

As the specific (meth) acrylic oligomer, after reacting an epoxy resin having a polysulfide skeleton with a compound having a functional group such as an amine, a carboxylic acid, a hydroxyl group, or a thiol, in addition to the above, the epoxy group becomes The hydroxyl group formed by ring opening is further reacted with an organic diisocyanate such as tolylene diisocyanate and a (meth) acrylate having a hydroxyl group such as hydroxyethyl acrylate to obtain a polyurethane (meth) acrylate having a polysulfide skeleton. Is also good.
Further, after reacting an epoxy resin having a polysulfide skeleton with a compound having a functional group such as an amine, a carboxylic acid, a hydroxyl group, or a thiol, a hydroxyl group formed by opening of the epoxy group is reacted with acrylic acid to obtain an acrylic oligomer. And you may use it.

In preparing the ultraviolet-curable composition, not only the specific skeleton-containing (meth) acrylic oligomer described above, but also a monofunctional (meth) acrylate or a polyfunctional (meth) acrylate is used in combination as a polymerizable monomer component. You can do it. Each of these can be used alone or in combination of two or more.

Examples of the polymerizable monomer that can be used in the present invention include the following. Examples of the monofunctional (meth) acrylate include, as a substituent, methyl, ethyl, propyl, butyl, amyl, 2-ethylhexyl,
Octyl, nonyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, nonylphenoxyethyl, tetrahydrofurfuryl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-
Having a group such as 2-hydroxypropyl, dimethylaminoethyl, diethylaminoethyl, nonylphenoxyethyltetrahydrofurfuryl, caprolactone-modified tetrahydrofurfuryl, isobornyl, dicyclopentanyl, dicyclopentenyl, dicyclopentenyloxyethyl, etc. A) acrylate and the like.

Examples of the polyfunctional (meth) acrylate include 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl-acrylate.
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, tricyclodecanedimethanol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, etc. Diacrylate, tris (2-hydroxyethyl)
Di (meth) acrylate of isocyanurate, di (meth) acrylate of diol obtained by adding at least 4 mol of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol, 2 mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A Of triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of diol di (meth) acrylate obtained by the addition of trimethylolpropane, and 4 moles per 1 mole of bisphenol A. Di (meth) acrylate / tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate of diol obtained by adding at least mole of ethylene oxide or propylene oxide, trimethylol Propane tri (meth) acrylate, pentaerythritol tri (meth) acrylate /
Dipentaerythritol poly (meth) acrylate /
Caprolactone-modified tris [(meth) acryloxyethyl] isocyanurate, alkyl-modified dipentaerythritol poly (meth) acrylate, caprolactone-modified dipentaerythritol poly (meth) acrylate / hydroxypentivalate neopentyl glycol diacrylate, caprolactone-modified hydroxy Neopentyl glycol diacrylate pivalate / ethylene oxide-modified phosphoric acid (meth) acrylate, ethylene oxide-modified alkylated phosphoric acid (meth) acrylate, and the like.

Further, N-vinyl-2-pyrrolidone, acryloylmorpholine, vinylimidazole, N-vinylcaprolactam, vinyl acetate, (meth) acrylic acid,
(Meth) acrylamide, N-hydroxymethylacrylamide or N-hydroxyethylacrylamide and their alkyl ether compounds can also be used.

Further, the same as the polymerizable monomer can be used in combination with polyester poly (meth) acrylate, polyether poly (meth) acrylate, polyetherester polyurethane (meth) acrylate, and epoxy polyether known and used as polymerizable oligomer. (Meth) acrylate and the like.

In preparing the composition of the present invention,
In addition to using the (meth) acrylic oligomer having the specific skeleton, the chemical composition is appropriately selected so that the physical properties of the composition itself and the physical properties of the cured film become suitable for an optical disc aimed at. In the case of a DVD, the chemical composition is appropriately selected according to each type of the DVD so that the physical properties of the composition itself and the physical properties of the cured layer are suitable for the DVD.

As a criterion at this time, it is premised that the information recorded in the information recording layer is not deteriorated, that is, that no abnormalities occur in the pits. Or have no level separation, have high wettability to both surfaces to be bonded, and have leveling property to provide a smooth and uniform wet surface in a short time. The two surfaces to be bonded should contain as little as possible substances or ions that cause corrosion or deterioration of the surface, the composition before curing has a certain degree of adhesiveness even in a liquid state, and a gas that contributes to the inhibition of curing. The composition must have as low a solubility as possible, and the composition must have the transparency to transmit ultraviolet rays as high as possible before and after curing, and the adhesion between the two laminated layers and the cured layer must be greater. , Same curing The elastic modulus of the specific range, to reduce the moisture permeability of the cured layer as much as possible, to minimize the shrinkage of the same composition before and after curing, and The measured values of these evaluation items are excellent as absolute values, and the change between these absolute values between a normal state and a high-temperature, high-humidity, long-time exposure is as small as possible. An ultraviolet curable composition containing a photopolymerization initiator is prepared so as to satisfy all of these criteria or as many as possible.

As the photopolymerization initiator that can be used in the present invention, any one can be used as long as it generates a radical by light and the radical efficiently reacts with the polymerizable unsaturated compound. There are a type in which a molecule is cleaved to generate a radical and a type in which a compound such as a combination of an aromatic ketone and a hydrogen donor is used in combination.

Examples of the former include, for example, benzoyl ethyl ether, benzoin isobutyl ether,
Benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1
-Phenyl-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-
(4-Isopropylphenyl) -2-hydroxy-2-
Methylpropan-1-one and 2-methyl-1- (4-
Methylthiophenyl) -2-morpholino-propanone-
1-one, bis (2,6-dimethoxybenzoyl)-
2,4,4-trimethylpentylphosphine oxide and the like can be mentioned.

The aromatic ketones of the latter examples include, for example, 4-phenylbenzophenone, isophthalophenone, 4-benzoyl-4'-methyl-diphenylsulfide, 2,4-diethylthioxanthone, 2-isopropylthioxanthone and Examples thereof include 2-chlorothioxanthone and the like, and examples of the hydrogen donor combined therewith include a mercapto compound and an amine compound, and an amine compound is generally preferable.

Examples of the amine compound include triethylamine, methyldiethanolamine, triethanolamine, diethylaminoethyl (meth) acrylate, p-dimethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, , N-dimethylbenzylamine and 4,
4'-bis (diethylamino) benzophenone and the like.

These photopolymerization initiators may be used alone or in combination of two or more. As the photopolymerization initiator, one having an absorption wavelength in a region of 370 nm or more and having a molar extinction coefficient of 50 (l / mol cm) or more at 370 to 450 nm is essential. It is preferable to use a combination of a molecular cleavage type or a hydrogen abstraction type which does not belong to the above.
When obtaining DVD-5, it is preferable that the resin substrate is not whitened. The amount of the photopolymerization initiator used is not particularly limited, but is usually 100
0.1 to 8 parts by weight per part by weight.

If necessary, the composition of the present invention may further contain, as other additives, antioxidants represented by thermal polymerization inhibitors, hindered phenols, hindered amines, phosphites, etc., plasticizers and the like. Epoxy silane,
A silane coupling agent typified by mercaptosilane, (meth) acrylsilane and the like can be blended in a conventional amount for the purpose of improving various properties. These are selected from those having excellent solubility in the curable component and those that do not impair the ultraviolet transmittance.

As the composition of the present invention, one containing as little chlorine ions as corrosive to the metal constituting the thin film, preferably 500 ppm or less is used.

The UV-curable composition may be used at room temperature to 40
It is preferable to use one that is liquid at a temperature of ° C. It is preferable not to use a solvent, and even if it is used, it is preferable to keep it as small as possible. When the composition is applied by a spin coater, the viscosity is preferably adjusted to 20 to 1000 centipoise, and when the composition is relatively thick, the viscosity is adjusted to 100 to 1000 centipoise. Is good.

When the composition of the present invention is used for bonding a DVD, the film thickness (layer thickness) after curing is usually from 30 to 30%.
The thickness is set to 60 μm (micron). In addition, the composition of the present invention may be applied to one of the surfaces of the two disk substrates to be bonded to each other, or to both of them.

In the present invention, an optical disk generally refers to an optical disk that optically reads and reproduces recorded information based on irregularities on a metal thin film. The ultraviolet-curable composition of the present invention,
It can be used to bond two identical or different disks having an information recording layer on at least one disk. The ultraviolet-curable composition of the present invention has excellent adhesiveness to not only aluminum, but also gold, silicon nitride and silicon carbide thin films, so that it can be used for protective coating and adhesion of any conventional optical disks. Yes, but D
It is suitably used for bonding two disk substrates to be bonded in VD manufacturing.

The disk substrate is formed by laminating a metal thin film with irregularities corresponding to recorded information on a heat-resistant resin. Examples of the heat-resistant resin include polycarbonate resin, amorphous polyolefin, and acrylic resin. Examples thereof include aluminum, gold, silicon nitride, silicon carbide and the like. As the resin constituting the substrate, one containing as little as possible chlorine ions or the like which are corrosive to the metal constituting the thin film, preferably 1 ppm or less is used.

The composition of the present invention comprises a disc substrate having an information recording layer on both disc substrates to be bonded, one of which is a polycarbonate substrate on which an aluminum thin film is formed, and the other of which is gold, In the case of a polycarbonate substrate on which a thin film of silicon nitride or silicon carbide is formed, it can be particularly preferably used for adhesion between an aluminum thin film and a thin film of gold, silicon nitride or silicon carbide. Of the two metal thin films (information recording layers) in DVD-9, the thin film of gold, silicon nitride or silicon carbide has a higher ultraviolet transmittance than aluminum and the same thickness of gold, silicon nitride or carbon carbide at the same film thickness. When the silicon thin film and the aluminum thin film are integrated by an ultraviolet-permeable adhesive, not only the recorded information on the former thin film but also the recorded information on the latter thin film can be read through the former thin film.

In the present invention, when two disks having an information recording layer are bonded to at least one disk, the exposed information recording layer (for example, a metal thin film surface) may be directly bonded. The protective coating layer may be provided only on the exposed surface of the information recording layer, and then the protective coating layer and the information recording layer may be bonded. In this case, this protective coat layer is also usually formed of a cured product of the ultraviolet curable composition. In this case, this protective coat layer needs to be transparent to ultraviolet rays. The ultraviolet-curable composition for the protective coat layer is preferably prepared so as to have excellent adhesiveness to both the exposed surface of the information recording layer and the cured product of the ultraviolet-curable composition for bonding disks together. .

Further, the composition of the present invention can be used as an ultraviolet irradiation method for curing, in addition to using continuous light irradiation, which is generally widely used, as well as the irradiation light amount required for curing by conventional continuous light irradiation. The same amount or less light amount, for example, μsec
Irradiation may be performed at once in a short time of the order of ~ msec, or may be performed by a flash irradiation method in which irradiation is divided and repeated.

The light irradiation may be performed only from one side of the opposed disk, or may be performed from both sides. In the case of performing irradiation from only one side of the DVD-9, the amount of irradiation energy can be reduced by irradiating ultraviolet rays from the outside of a disk substrate having a metal thin film having a higher transmittance of ultraviolet rays used for curing. Similarly, in the case of performing irradiation from only one side of the DVD-5, when the UV light used for curing is higher, the UV light is transmitted from the outside of the dummy disk substrate having no information recording layer, which is made of only a heat-resistant resin and has no information recording layer. Irradiation requires less irradiation energy.

When a single disc having no information recording layer such as the above-mentioned DVD-5 is used, a transparent polycarbonate substrate may be directly adhered,
A disk on which offset printing or the like has been performed may be bonded to the surface to be bonded in advance.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention includes the following embodiments.

1. An ultraviolet curable composition for an optical disc having a film selected from the group consisting of gold, silicon nitride and silicon carbide, comprising a (meth) acrylic oligomer containing a polysulfide skeleton in a molecule.

2. 2. The ultraviolet-curable composition according to the above item 1, wherein the optical disk is one in which two disks each having an information recording layer are bonded to at least one disk.

3. 3. The ultraviolet-curable composition according to the above 1 or 2, wherein the (meth) acrylic oligomer is obtained by reacting an epoxy resin having a polysulfide skeleton with (meth) acrylic acid.

4. The two disks to be bonded are both disks having an information recording layer, one is a polycarbonate substrate on which a thin film of aluminum is formed, and the other is a disk on which a thin film of gold, silicon nitride or silicon carbide is formed. 1 and 2 above, which are polycarbonate substrates
Or the ultraviolet-curable composition according to 3.

5. 5. The ultraviolet-curable composition according to the above 1, 2, 3, or 4, further comprising a polyether polyurethane (meth) acrylate.

6. When bonding two disks having an information recording layer to at least one disk, in the ultraviolet-curable composition for an optical disk containing an ultraviolet-curable compound and a photopolymerization initiator, the ultraviolet-curable compound is Contains polysulfide skeleton in the molecule (meta)
An ultraviolet curable composition for an optical disc, which is an acrylic oligomer.

7. 7. The ultraviolet-curable composition according to the above 6, further comprising a polyether polyurethane poly (meth) acrylate.

8. 7. The ultraviolet-curable composition according to the above 6, further comprising a polyether polyurethane poly (meth) acrylate and a monofunctional (meth) acrylate.

9. 6. The photopolymerization initiator according to the above 6, 7, or 8, wherein a photopolymerization initiator having an absorption wavelength in a region of 370 nm or more and having a molar absorption coefficient of 50 (l / mol cm) or more in a range of 370 to 450 nm is essential. Composition.

10. As a photopolymerization initiator, one having an absorption wavelength in a region of 370 nm or more and having a molar absorption coefficient of 50 (l / mol cm) or more in a range of 370 to 450 nm, a molecule cleavage type not belonging to the above or 9. The composition according to the above 6, 7, or 8, which comprises both a hydrogen abstraction type.

A preferred embodiment of the present invention is as follows. Using an acrylic oligomer containing a polysulfide skeleton in a molecule obtained by reacting an epoxy resin having an -SS- bond with acrylic acid, polytetramethylene ether polyurethane diacrylate, and a monofunctional (meth) acrylate , Per 100 parts by weight of the curable component, 3
Having an absorption wavelength in the region of 70 nm or more, and
At 50 nm, the molar extinction coefficient is 50 (l / mol cm)
3 to 6 parts by weight of a photopolymerization initiator, including both those having the above and those not belonging to the above-mentioned molecular cleavage type or hydrogen abstraction type, are mixed to obtain a mixture having a viscosity of 100 to 1000 poise (normal temperature). An ultraviolet curable composition containing no organic solvent is prepared.

Of two polycarbonate discs having a thickness of about 0.6 mm each having a different concavo-convex pattern corresponding to the recorded information, gold is vapor-deposited on one concavo-convex surface so as to be translucent. Then, aluminum is deposited and laminated on another sheet.

The above composition is applied to one of the metal-deposited surfaces of the information recording layer of the two disks by a spin coater so that the film thickness after curing becomes 30 to 60 μm, and the centers coincide. As described above, the two metal thin film surfaces are directly opposed to each other and bonded.

Next, the metal thin film is irradiated with ultraviolet rays from the outside of the gold polycarbonate disc, and if necessary, the metal thin film is also irradiated with ultraviolet rays from the outside of the aluminum polycarbonate disc. Then, the composition layers of both metal thin films are cured and bonded to obtain one finished DVD-9 disk.

[0053]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Hereinafter, "parts" in the examples means "parts by weight".

Example 1 FLEP-60 (manufactured by Toray Thiokol Co., Ltd., epoxy equivalent: 280) 280 mainly containing a polysulfide-modified epoxy resin containing a polysulfide skeleton in the molecule
10 g of an acrylic oligomer obtained by reacting 71 g of acrylic acid at 100 ° C. with N, N-dimethylbenzylamine as a catalyst, and polytetramethylene glycol (molecular weight: 85
0) After reacting 1 mol with 2 mol of tolylene diisocyanate, 30 parts of urethane acrylate obtained by reacting 2 mol of hydroxyethyl acrylate, 36 parts of nonylphenol EO-modified acrylate, 20 parts of tetrahydrofurfuryl acrylate, and 2,4 as a photopolymerization initiator 2,6-trimethylbenzoyldiphenylphosphine oxide (2 parts) and benzyldimethylketal (2 parts) were mixed and dissolved at 60 ° C. for 1 hour to prepare a pale yellow transparent ultraviolet-curable composition. Using this composition, a bonded disk was produced by the following test method 1. Next, a notch was made in the end face of the disc with a cutter, and the two discs were peeled off. The two discs were peeled off from the interface between the aluminum and the polycarbonate substrate and from the interface between the gold and the polycarbonate substrate. Was firmly adhered to.

Example 2 A laminated disk was produced by using the same ultraviolet-curable composition as in Example 1 and by the following test method 2. Next, a notch was made on the end face of the disc with a cutter, and the two discs were peeled off. The two discs were peeled off from the interface between aluminum and the polycarbonate substrate and from the interface between silicon nitride and the polycarbonate substrate. It was very strongly bonded to silicon.

COMPARATIVE EXAMPLE 1 1 part of polytetramethylene glycol (molecular weight: 850) was reacted with 2 mol of tolylene diisocyanate and then reacted with 2 mol of hydroxyethyl acrylate. Forty parts of urethane acrylate, 36 parts of nonylphenol EO-modified acrylate, tetrahydrofurfuryl Acrylate 20
And 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator and 2 parts of benzyldimethylketal were mixed and dissolved at 60 ° C. for 1 hour to prepare a pale yellow transparent ultraviolet curable composition. Using this composition, a bonded disk was produced by the following test method 1. Next, make a notch on the disk end face with a cutter and
When the discs were peeled off, they peeled off from the interface between the cured product of the ultraviolet curable composition and gold, and the adhesion to gold was weak.

<Test Method 1> Aluminum having a thickness of 500 angstroms as a metal thin film having a diameter of 12
The above composition was applied to a disc-shaped polycarbonate substrate with a dispenser.
A transparent disc-shaped polycarbonate substrate having a diameter of 12 cm and having a thickness of Å was superposed. The coating amount was such that when the composition was pushed and spread using only the weight of the substrate, the film thickness of the composition became 40 μm. Then, irradiation intensity 1000 mW / cm ² to adjust the condensing type metal halide lamp (with a cold mirror, lamp output 80W / cm) using the installed belt conveyor type UV irradiation device, and cured at an irradiation light amount of about 1000 mJ / cm ^2.

<Test Method 2> Aluminum having a diameter of 12 Å formed to a thickness of 500 Å as a metal thin film.
The above composition was applied to a disc-shaped polycarbonate substrate having a thickness of 200 cm with a dispenser, and then a transparent disc-shaped polycarbonate substrate having a diameter of 12 cm formed of silicon nitride and having a thickness of 200 angstroms was overlaid. The coating amount was such that when the composition was pushed and spread using only the weight of the substrate, the film thickness of the composition became 40 μm. Then, irradiation intensity 1
Curing was performed at an irradiation light amount of about 1000 mJ / cm ² using a belt conveyor type ultraviolet irradiation apparatus equipped with a condensing metal halide lamp (with a cold mirror, lamp output 80 W / cm) adjusted to 000 mW / cm ² .

The composition of Example 1 was used when two discs to be bonded were used, both of which had an aluminum layer formed as a metal thin film, or one was a transparent polycarbonate having no information recording layer. Even when the substrate is used (DVD-5), the polycarbonate substrate shows a strong adhesive force without whitening on the polycarbonate substrate side.
It was suitable as an ultraviolet curable composition used as an adhesive for VD.

In this embodiment, the continuous illumination light, which is generally widely used as the ultraviolet irradiation system, is used. However, similar results are obtained with a lower irradiation energy as a whole when the flash irradiation system is used. .

An ultraviolet-curable composition for an optical disk was prepared using the thioether-containing photopolymerizable compound described in JP-A-7-320299. The working environment for manufacturing optical discs was extremely inferior with strong odor.

[0062]

Since the composition of the present invention contains a (meth) acrylic oligomer containing a polysulfide skeleton in the molecule, the composition of the present invention can be compared with the case of using a thioether-containing photopolymerizable compound having one sulfur atom. The working environment for manufacturing optical discs can be greatly improved. Moreover, not only polycarbonate and aluminum, but also gold, which had poor adhesion, and strong adhesion to the hardened surface of printing ink can be obtained, so that a highly reliable optical disc can be produced. Has a remarkable effect. The compositions of the present invention are particularly suitable for producing reliable DVD-9 discs.

Claims (4)

[Claims] 1. An ultraviolet-curable optical disk for an optical disc having a film selected from the group consisting of gold, silicon nitride and silicon carbide, comprising a (meth) acrylic oligomer containing a polysulfide skeleton in the molecule. Composition. 2. The ultraviolet-curable composition according to claim 1, wherein the optical disk is formed by bonding at least one disk to two disks having an information recording layer. 3. The ultraviolet-curable composition according to claim 1, wherein the (meth) acrylic oligomer comprises an epoxy resin having a polysulfide skeleton and acrylic acid. 4. The two disks to be bonded are both disks having an information recording layer, one is a polycarbonate substrate on which an aluminum thin film is formed, and the other is
3. The ultraviolet-curable composition according to claim 2, wherein the sheet is a polycarbonate substrate on which a thin film of gold, silicon nitride or silicon carbide is formed.