JPH11315132A - Ultraviolet-hardenable composition for optical disk, and optical disk by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ultraviolet-hardenable composition for an optical disk, which is an adhesive used when sticking two substrates having recording layers, hardly causing corrosion of a reflection coating film composed of aluminum and the like, and a recording membrane under a high temperature and high humidity condition, and capable of forming a uniform transparent adhesive layer. SOLUTION: This ultraviolet-hardenable composition usable when sticking two substrates having recording layers so that the recording layers may be inside comprises (A) a glycidyl ether-type epoxy resin composition and (B) a cationic photopolymerization initiator, and the chlorine content in the epoxy resin composition A is regulated so as to be <=1 wt.%. The optical disk is obtained by sticking the two substrates having the recording layers so that the recording layers may be inside by using the ultraviolet-hardenable composition as an adhesive.

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 used when two substrates having a recording layer are bonded to at least one substrate, and an optical disk having the same as an adhesive. .

[0002]

2. Description of the Related Art Recently, a digital versatile disk or a digital video disk (DVD) capable of recording high-density and large-capacity information among optical disks has attracted attention.
DVDs have a structure in which two substrates having a recording layer are bonded together for higher density. As an adhesive for bonding two substrates, a hot melt adhesive,
A radical polymerization type ultraviolet curing adhesive, a cationic polymerization type ultraviolet curing adhesive, and the like have been proposed.

[0003] The hot-melt type adhesive mainly uses a thermoplastic resin, so that it has poor heat resistance and has a problem that the disk is easily deformed or peeled off by heat. In addition, since the radical polymerization type ultraviolet curable adhesive irradiates ultraviolet rays through the substrate, the metal reflective film and the recording film, sufficient ultraviolet light does not reach the adhesive, and ultraviolet light having high intensity for curing is used. However, there are problems such as the necessity of the curing, a long curing time, and insufficient curing with ordinary intensity ultraviolet rays.

[0004] On the other hand, the cationically polymerizable UV-curable adhesive, once irradiated with ultraviolet light, cures even in a dark place. Can be bonded. Utilizing this feature, JP-A-61-165842, JP-A-62-129957, and JP-A-63-129957
JP-78351-A discloses a cationic polymerization type ultraviolet curing adhesive using a bisphenol type epoxy resin having a glycidyl group, an aliphatic polyol polyglycidyl ether type epoxy resin or an alicyclic epoxy resin and a photocationic polymerization initiator. Is disclosed. Also, JP-A-7-12
JP-A-6577 and JP-A-9-69239 propose a method of manufacturing an optical disc in which the adhesive is applied to a substrate, irradiated with ultraviolet rays, and then the other substrate is attached. The adhesive layer produced by this method cures sufficiently and becomes a film having higher heat resistance than a hot-melt adhesive.

However, since cationic cationic polymerization initiators are used in these cationically polymerizable UV-curable adhesives, optical cationic polymerization initiators or their decomposed products can be used to cure optical disks under high temperature and high humidity conditions. There has been a problem that the reflection film or recording film of aluminum or the like is corroded.

For the purpose of preventing such corrosion, Japanese Patent Application Laid-Open No. 9-69239 discloses a method of forming a protective film made of a radical polymerization type ultraviolet curable resin. JP-A-9-249834 discloses that a cationic cationic polymerization initiator is caused by adding an ion exchanger to a mixture of a bisphenol-type epoxy resin and an alicyclic polyfunctional epoxy resin having a terminal hydroxyl group. Attempts to trap corrosive components have been disclosed.

[0007] However, the former method has not been sufficiently satisfactory because the reflective film and the recording film are corroded when exposed for a long time under a high-temperature and high-humidity condition.

In the latter method, since the ion exchanger is made of inorganic particles, the protective film used in the latter method becomes white and opaque, and is formed of two layers from one side of an optical disk such as a DVD-9 system. There is a problem that the method cannot be applied to an optical disk of a type for reading information, and there is a problem that sedimentation or aggregation of an ion exchanger occurs during storage of the resin composition.

[0009]

As described above, in a conventional cationic polymerization type ultraviolet curing adhesive using a cationic photopolymerization initiator, corrosion is caused in a reflective film of aluminum or the like caused by the initiator. The use of a protective film or an ion exchanger is intended to prevent these problems, but the performance of the adhesive has not been satisfactory.

The problem to be solved by the present invention is an adhesive used for bonding two substrates having a recording layer, which corrodes a reflective film and a recording film made of aluminum or the like under high temperature and high humidity conditions. It is an object of the present invention to provide an ultraviolet-curable composition for an optical disc which forms a uniform and transparent adhesive layer without any problem and an optical disc using the same.

[0011]

A glycidyl ether type epoxy resin is mainly used for a conventional cationic polymerization type ultraviolet curing adhesive using a photocationic polymerization initiator, and a reflection film such as aluminum is used. The corrosion was attributed to the cationic photopolymerization initiator. However, the present inventors have found that chlorine-based impurities contained in the epoxy resin cause corrosion of a reflection film or a recording film of aluminum or the like, the glycidyl ether type epoxy resin composition (A) and the cationic photopolymerization. In the ultraviolet curable composition comprising the initiator (B), it has been found that corrosion of the reflection film and the recording film can be prevented by controlling the amount of chlorine in the epoxy resin composition (A) to 1% by weight or less, The present invention has been completed.

In addition, the present inventors have proposed a method of irradiating an ultraviolet ray to a cationic polymerization type ultraviolet-curing adhesive, applying the adhesive to a substrate surface, and then bonding the adhesive to the other substrate. It is preferable to combine a bisphenol-type diglycidyl ether with an aliphatic diol diglycidyl ether in order to maintain the liquid state for a certain period of time after irradiating the adhesive with ultraviolet rays, and to impart the property of bonding and curing. Further, in these cationically polymerizable ultraviolet-curable adhesives, by coexisting a compound having an oxetane ring, it is found that curing of the bonded end face proceeds particularly effectively, and to complete the present invention. Reached.

That is, the present invention provides a UV-curable composition used when two substrates having a recording layer are bonded together with the recording layer side inward. An ultraviolet curable resin composition comprising an epoxy resin composition (A) and a cationic photopolymerization initiator (B), wherein the amount of chlorine in the epoxy resin composition (A) is 1% by weight or less. Composition,

(2) The glycidyl ether type epoxy resin composition (A) is an epoxy resin composition comprising (A-1) bisphenol type diglycidyl ether and (A-2) aliphatic diol diglycidyl ether. 1) The ultraviolet-curable composition according to the above,

(3) The bisphenol type diglycidyl ether (A-1) is hydrogenated bisphenol A diglycidyl ether, and the aliphatic diol diglycidyl ether (A-2) is propylene glycol diglycidyl ether, neopentyl. The ultraviolet-curable composition according to (2), which is at least one compound selected from the group consisting of glycol diglycidyl ether, butanediol diglycidyl ether, hexanediol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether.

(4) The cationic photopolymerization initiator (B) is
The cation moiety is aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium and (2,4-cyclopentadien-1-yl) [(1-
Methylethyl) benzene] -Fe cation, wherein the anion moiety is a general formula [BX ₄ ] ⁻ (where X is a phenyl group substituted with at least two or more fluorine or trifluoromethyl groups). The ultraviolet-curable composition according to any one of the above (1) to (3), which is a structured onium salt,

(5) The ultraviolet-curable composition according to any one of (1) to (4), further comprising a compound (C) having an oxetane ring.

(6) An optical disk in which two substrates having a recording layer are bonded together with an adhesive with the recording layer side inside, wherein the adhesive is any one of the above (1) to (5). An optical disc which is an ultraviolet curable composition of

(7) In a method of manufacturing an optical disk in which two substrates having a recording layer are bonded together with the recording layer side inside using an adhesive, the adhesive described in (1) to (1) above is used as an adhesive.
Using the ultraviolet-curable composition according to any of (5), the adhesive is dropped in a ring shape on at least one of the substrates to be bonded while irradiating with ultraviolet light, and then the two substrates are stacked. Bonding, and then spreading the adhesive by rotating at high speed, a method for manufacturing an optical disc,

(8) In a method of manufacturing an optical disk in which two substrates having a recording layer are bonded together with the recording layer side inside using an adhesive, the adhesive described in (1) to (1) above is used as an adhesive.
Using the ultraviolet-curable composition according to any of (5), the adhesive is dropped in a ring shape on the surface of the two substrates to be bonded while irradiating ultraviolet rays, and then the two substrates are stacked. Bonding, and then spreading the adhesive by its own weight or pressure, a method for manufacturing an optical disc,

(9) In a method for manufacturing an optical disk in which two substrates having a recording layer are bonded together with the recording layer side inside using an adhesive, the above-mentioned (1) to
Using the ultraviolet-curable composition according to any one of (5), the adhesive is dropped in a ring shape on at least one of the substrates on the side to be bonded, and irradiated with ultraviolet light, and then the two substrates are stacked. A method of manufacturing an optical disc, wherein the adhesive is spread by rotating at a high speed.

(10) In a method for manufacturing an optical disk in which two substrates having a recording layer are bonded together with the recording layer side inside using an adhesive, the adhesive described in (1) to (1) above is used as an adhesive.
(5) using the ultraviolet-curable composition according to any one of (1) to (3), the adhesive is dropped in a ring shape on the surface to be bonded of the two substrates, and both substrates are irradiated with ultraviolet light; And then spreading the adhesive under its own weight or by applying pressure.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The glycidyl ether type epoxy resin composition (A) used in the present invention is composed of one or more glycidyl ether type epoxy resins. The glycidyl ether type epoxy resin can be produced by reacting a polyhydric phenol compound or a polyhydric alcohol with epichlorohydrin.

The epoxy resin usually contains chlorine-bonded organic molecules as impurities due to the raw material epichlorohydrin. In particular, the alcohol ether type epoxy resin contains a large amount of chlorine type impurities.

In the ultraviolet curable composition of the present invention, it is essential that the amount of chlorine in the glycidyl ether type epoxy resin composition (A) is 1% by weight or less. For this purpose, at least the total amount of chlorine in each compound as a raw material of the glycidyl ether type epoxy resin composition (A) should be 1
% By weight or less.

The chlorine contained in the epoxy resin is a value obtained by forcibly decomposing bound chlorine contained in an organic molecule with metallic sodium and measuring the liberated chlorine by titration or back titration. It indicates the total chlorine content.

The glycidyl ether type epoxy resin (A) used in the present invention can be used without particular limitation as long as the amount of chlorine in the resin is 1% by weight or less. The glycidyl ether type epoxy resin is roughly classified into bisphenol type diglycidyl ether, novolak type epoxy resin, aliphatic polyol polyglycidyl ether and the like.

The bisphenol-type diglycidyl ether includes, for example, diglycidyl ether of bisphenol A or its alkylene oxide adduct, diglycidyl ether of bisphenol F or its alkylene oxide adduct, hydrogenated bisphenol A or its alkylene oxide adduct. And diglycidyl ether.

Examples of the novolak type epoxy resin include phenol novolak type epoxy resin, o-cresol novolak type epoxy resin, diphenylolpropane novolak type epoxy resin, dicyclopentadiene phenol type epoxy resin, and the like.

Examples of the aliphatic polyol polyglycidyl ether include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether,
Neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, hexanediol diglycidyl ether, cyclohexane dimethanol diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol triglycidyl Ether, pentaerythritol tetraglycidyl ether, sorbitol heptaglycidyl ether, sorbitol hexaglycidyl ether and the like.

Other glycidyl ether type epoxy resins include, for example, resorcin diglycidyl ether.

Among these glycidyl ether type epoxy resins, a glycidyl ether type epoxy resin composition comprising a combination of (A-1) a bisphenol type diglycidyl ether and (A-2) an aliphatic diol diglycidyl ether is preferable. Among these combinations, (A-1) hydrogenated bisphenol A diglycidyl ether and (A-2) propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, hexanediol diglycidyl ether 1 selected from the group consisting of cyclohexane dimethanol diglycidyl ether
When the glycidyl ether type epoxy resin composition composed of a combination with at least one kind of aliphatic diol diglycidyl ether is used as an ultraviolet-curable composition for an optical disc, the anticorrosion effect of a reflective film or a recording film under high temperature and high humidity conditions is high. It is particularly preferable because of its low water absorption.

The aliphatic polyol diglycidyl ether type epoxy resin having a chlorine content of 1% by weight or less can also be obtained as a commercial product. For example, NPG-DGE low chlorine product (Neopentyl manufactured by Sakamoto Yakuhin Co., Ltd.) Diglycidyl ether, total chlorine content = 0.91% by weight), 16H-DGE low chlorine product (hexanediol diglycidyl ether manufactured by Sakamoto Pharmaceutical Co., Ltd., total chlorine content = 0.49% by weight), CHDM-
DGE low chlorine product (cyclohexane dimethanol diglycidyl ether manufactured by Nagase Kasei Co., Ltd., total chlorine content = 0.19
% By weight).

Further, for example, bisphenol A glycidyl ether having a low chlorine-based impurity (eg, Epicron 8)
50S, Dainippon Ink and Chemicals, total chlorine = 0.1
(4% by weight) with a ruthenium catalyst or the like, hydrogenated bisphenol A diglycidyl ether having low chlorine-based impurities (total chlorine amount = 0.14% by weight) can be obtained.

The cationic photopolymerization initiator (B) used in the present invention is a compound which initiates cationic polymerization of an epoxy group upon irradiation with ultraviolet rays. Examples thereof include (1) aromatic sulfonium, aromatic iodonium, and aromatic diazonium. , Aromatic ammonium, (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -F
a cation selected from the group consisting of e cations, and (2)
BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , general formula [BX ₄ ] ⁻ (wherein,
X represents a phenyl group in which at least two or more hydrogen atoms on the benzene ring are substituted with fluorine or a trifluoromethyl group. And an anion selected from the group consisting of:

Examples of the aromatic sulfonium salt-based cationic photopolymerization initiator include bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate and bis [4- (diphenylsulfonio) phenyl] sulfide bishexa. Fluoroantimonate, bis [4- (diphenylsulfonio) phenyl] sulfide bistetrafluoroborate, bis [4-
(Diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium hexafluorophosphate, diphenyl-4- (phenylthio) phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio) Phenylsulfonium tetrafluoroborate, diphenyl-4-
(Phenylthio) phenylsulfonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorophenyl)
Borate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide
Bishexafluorophosphate, bis [4- (di (4
-(2-hydroxyethoxy)) phenylsulfonio)
Phenyl] sulfide bishexafluoroantimonate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bistetrafluoroborate, bis [4- (di (4- (2
-Hydroxyethoxy)) phenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, and the like.

Examples of the aromatic cationic iodonium salt-based cationic photopolymerization initiator include diphenyliodonium hexafluorophosphate and diphenyliodonium.
Hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) iodonium hexafluorophosphate, bis (dodecylphenyl) iodonium hexafluoroantimonate, bis (dodecylphenyl) iodonium tetrafluoro Borate, bis (dodecylphenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-
4- (1-methylethyl) phenyliodonium hexafluorophosphate, 4-methylphenyl-4-
(1-methylethyl) phenyliodonium hexafluoroantimonate, 4-methylphenyl-4- (1
-Methylethyl) phenyliodonium tetrafluoroborate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrakis (pentafluorophenyl) borate, and the like.

Examples of the aromatic diazonium salt-based cationic photopolymerization initiator include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, and phenyldiazonium tetrakis (pentafluorophenyl) borate. No.

Examples of the aromatic ammonium salt-based cationic photopolymerization initiator include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2- Cyanopyridinium tetrafluoroborate, 1-benzyl-2-cyanopyridinium tetrakis (pentafluorophenyl) borate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluoro Antimonate, 1- (naphthylmethyl) -2-cyanopyridinium tetrafluoroborate, 1- (naphthylmethyl) -2-cyanopyridinium tetrakis (pentafluorophenyl) borate, And the like.

Examples of the (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -Fe salt-based cationic photopolymerization initiator include, for example, (2,4-cyclopentadien-1-yl) ) [(1-methylethyl) benzene] -Fe (II) hexafluorophosphate,
(2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -Fe (II) hexafluoroantimonate, 2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene ] -Fe (II) tetrafluoroborate, 2,4-cyclopentadiene-
1-yl) [(1-methylethyl) benzene] -Fe
(II) tetrakis (pentafluorophenyl) borate, and the like.

Commercially available photocationic polymerization initiators (B) include, for example, “UVI6909” (manufactured by Union Carbide Co., Ltd., bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate and triphenylsulfonium hexafluoro). A mixture of phosphate), "UVI6974" (a mixture of bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate and triphenylsulfonium hexafluoroantimonate manufactured by Union Carbide), and "SP-150" (Asahi Screw [4] manufactured by Denka Co., Ltd.
-(Di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide bishexafluorophosphate), "SP-170" (Asahi Denka Co., Ltd.'s bis [4- (di (4- (2 -Hydroxyethoxy)))
Phenylsulfonio) phenyl] sulfide bishexafluoroantimonate), “FC-508” (3M
), "FC-512" (manufactured by 3M), "Irgacure 261" ((2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -manufactured by Ciba Specialty Chemicals) Fe (II) hexafluorophosphate), "RHODORSIL2"
074 "(4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrakis (pentafluorophenyl) borate manufactured by Rhone Poulin Co.).

Of these cationic photopolymerization initiators,
(1) Aromatic sulfonium, aromatic iodonium, aromatic ammonium, (2,4-cyclopentadiene-1-
Yl) a cation selected from the group consisting of [(1-methylethyl) benzene] -Fe cation, (2) the general formula [BX _4] ^- (wherein, X is at least two or more hydrogen atoms on the benzene ring Represents a phenyl group substituted by fluorine or a trifluoromethyl group.) When the onium salt is used as an ultraviolet-curable composition for an optical disk, the reflection film or the recording film is not corroded. It is particularly preferable because it is small. Examples of such a cationic photopolymerization initiator include bis [4- (diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium tetrakis (pentafluorophenyl) borate, Triphenylsulfonium tetrakis (pentafluorophenyl) borate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, diphenyliodonium tetrakis (pentafluorophenyl) Borate, bis (dodecylphenyl) iodoniumtetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium Tetrakis (pentafluorophenyl) borate,
1-benzyl-2-cyanopyridinium tetrakis (pentafluorophenyl) borate, 1- (naphthylmethyl) -2-cyanopyridiniumtetrakis (pentafluorophenyl) borate, 2,4-cyclopentadien-1-yl) [(1- Methylethyl) benzene]-
Fe (II) tetrakis (pentafluorophenyl) borate and the like.

The cationic photopolymerization initiator (B) is selected from the above-mentioned materials and can be used alone or in combination of two or more. The amount of the cationic photopolymerization initiator used is not particularly limited, but is preferably 0.3 to 100 parts by weight of the ultraviolet curable composition from the viewpoint of economy and the like.
The range is preferably from 10 to 10 parts, and particularly preferably from 0.3 to 4 parts by weight. The amount of photo cationic polymerization initiator used is 0.3
If the amount is less than part by weight, it tends to be difficult to cure sufficiently. Therefore, if the amount of the cationic photopolymerization initiator is more than 4 parts by weight, the amount remaining as an uncured component in the coating film is reduced. And the long-term reliability of the optical disc tends to decrease, which is not preferable.

A sensitizer may be used in the ultraviolet-curable composition of the present invention in order to improve curability.
Examples of the sensitizer used for such a purpose include bilen, perylene, 2,4-diethylthioxanthone, and phenothiazine. When used in combination with a sensitizer, the amount used is a glycidyl ether type epoxy resin (A)
The range is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight.

Further, the ultraviolet curable composition of the present invention includes:
2-hydroxy-2-methyl-1-phenylpropane-
A photo-radical polymerization initiator such as 1-one, 1-hydroxycyclohexyl phenyl ketone can also be used in combination.
When used together with the photoradical polymerization initiator, the amount used is preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the glycidyl ether type epoxy resin (A).

The compound (C) having an oxetane ring can be used in combination with the ultraviolet-curable composition of the present invention.
As the compound having an oxetane ring, for example, 1,4
-Bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,4-bis [(3-methyl-3-oxetanylmethoxy) methyl] benzene, 3-methyl-
3-glycidyl oxetane, 3-ethyl-3-glycidyl oxetane, 3-methyl-3-hydroxymethyl oxetane, 3-ethyl-3-hydroxymethyl oxetane, and the like.

When the compound (C) having an oxetane ring is used in combination with the ultraviolet-curable composition of the present invention, the adhesive adheres to the outer peripheral end surface of the substrate in a shorter time when the substrates are bonded. Can be cured. When used together with the compound having an oxetane ring, the amount used is preferably in the range of 1 to 100 parts by weight based on 100 parts by weight of the glycidyl ether type epoxy resin (A).

Further, if necessary, a glycidyl ether type epoxy resin (A) may be added to the ultraviolet curable composition of the present invention.
Alternatively, a cationic polymerizable compound other than the compound (C) having an oxetane ring, a polyol, an inorganic filler, an inorganic ion exchanger, a leveling agent, an antioxidant, a viscosity modifier, a silane coupling agent, and the like can be used in combination.

Other cationically polymerizable compounds that can be used in combination with the ultraviolet-curable composition of the present invention include, for example, 3,
Alicyclic epoxy compounds such as 4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate and limonene diepoxide; tripropylene glycol divinyl ether, triethylene glycol divinyl ether, 1,4-butanediol divinyl ether;
Vinyl ether compounds such as cyclohexane dimethanol divinyl ether and divinyl ether of an alkylene oxide adduct of bisphenol A; alicyclic polyfunctional epoxy resin having a terminal hydroxyl group (“EHP” manufactured by Daicel Corporation)
E3150 ”) and the like.

Next, a method of manufacturing an optical disk in which two substrates having a recording layer are bonded with the recording layer side inside using an adhesive made of the ultraviolet-curable composition of the present invention will be described.

In the method for producing an optical disk of the present invention, an adhesive comprising the ultraviolet-curable composition of the present invention is formed by forming an adhesive layer having a uniform thickness on a substrate by spin coating, screen printing, or the like. After that, the target optical disk is obtained by irradiating ultraviolet rays and bonding another substrate. The adhesive comprising the ultraviolet-curable composition of the present invention has a high fluidity for a certain period of time even after irradiation with ultraviolet light. Therefore, in order to prevent bubbles from remaining in the adhesive layer, the following (1) to (4)
An optical disc can be obtained by employing the bonding method described in (1).

(1) While irradiating ultraviolet rays, an adhesive is dropped on one of the substrates and applied in a ring shape, and then the other substrate is overlaid and bonded by rotating the substrate at a high speed with a spin coater or the like. A method of spreading and bonding the agents.

(2) While irradiating ultraviolet rays, the adhesive is dropped on the two substrates and applied in a ring shape. Then, the surfaces on which the adhesive has been applied are opposed to each other and overlapped with each other. A method of spreading adhesive and bonding.

(3) The adhesive is dropped on one of the substrates and applied in a ring shape, and then irradiated with ultraviolet rays, the other substrate is superposed, and rotated at high speed using a spin coater or the like. How to spread and paste.

(4) The adhesive is dropped on the two substrates and applied in a ring shape. After that, the two substrates are irradiated with ultraviolet rays, the surfaces on which the adhesive has been applied are opposed to each other, and the substrates are overlapped with each other. A method in which the adhesive is spread by applying pressure and bonded.

When a spin coater is used, it is preferable to adjust the mixing ratio of the epoxy resin so that the viscosity of the adhesive is in the range of 20 to 1000 mPa · s.

Further, at the time of bonding the substrates, in order to accelerate the curing of the adhered adhesive, the ultraviolet light may be applied again to the outer circumferential end surfaces of the substrates in order to accelerate the curing of the adhered adhesive. .

When the substrate is adhered by using the ultraviolet-curable composition of the present invention, a method of directly adhering the recording layers to each other may be employed, and a protective coating layer composed of a radical polymerization type ultraviolet-curable composition is provided on the recording layer. And a method of bonding the protective coat layers to each other.

As a method of irradiating the ultraviolet-curable composition of the present invention with ultraviolet rays, a flash light irradiation method may be used in addition to a general continuous light irradiation method. Examples of the lamp serving as the ultraviolet light source include a metal halide lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a xenon lamp. The irradiation amount of the ultraviolet rays is preferably in the range of 50 to 1000 mJ / cm ² .

[0060]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, “parts” means “parts by weight”.

Example 1 Bisphenol A diglycidyl ether ("Epiclon 850S" manufactured by Dainippon Ink and Chemicals, Inc., total chlorine content = 0.14% by weight) was hydrogenated at a hydrogen pressure of 40 kg / kg in the presence of a ruthenium catalyst. cm ^2, and hydrogenated for 7 hours at a temperature 40 ° C., to obtain a total chlorine content = 0.14 wt% of hydrogenated bisphenol a diglycidyl ether.

80 parts of hydrogenated bisphenol A diglycidyl ether obtained by the above reaction and 1,6-hexanediol diglycidyl ether (“16H-DG” manufactured by Sakamoto Yakuhin Co., Ltd.)
E "low chlorine product, total chlorine content = 0.49% by weight) 20 parts, photocationic polymerization initiator" UVI6990 "(bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate manufactured by Union Carbide Co.) 0.5 part of [4- (diphenylsulfonio) phenyl] sulfide triphenylsulfonium hexafluorophosphate mixture) and a leveling agent “L-760”
0.2 "of 4" (manufactured by Nippon Unicar) was mixed and dissolved at 60 ° C for 1 hour to prepare a pale yellow, transparent, ultraviolet-curable composition (1). The ultraviolet curable composition (1) thus obtained
Was 236 mPa · s (25 ° C.).

Two DVD substrates on which an aluminum reflective film was formed were prepared, and the composition (1) was dropped in a ring shape on the inner peripheral side of one of the substrates on the reflective film side, and a metal halide lamp ( With cold mirror, lamp output 12
(0 W / cm) and irradiated with 400 mJ / cm ² of ultraviolet light. Next, the other substrate was overlapped with the reflection film inside, and the composition was spread between the two substrates by rotating at 1,500 revolutions per second using a spin coater. The optical disk thus manufactured was subjected to a 96-hour durability test in a thermo-hygrostat at 85 ° C. and a relative humidity (RH) of 95%. As a result, no corrosion was observed on the aluminum reflective film.

Example 2 60 parts of hydrogenated bisphenol A diglycidyl ether obtained in Example 1 and cyclohexanedimethanol diglycidyl ether (“CHDM-DGE” manufactured by Nagase Kasei Co., Ltd., low chlorine product, total chlorine content) = 0.19
Weight%) 40 parts, photo cationic polymerization initiator "UVI699
0 "(manufactured by Union Carbide Co., Ltd.) and 0.2 part of a leveling agent" L-7604 "(manufactured by Nippon Unicar Co., Ltd.) were mixed and dissolved at 60 ° C. for 1 hour, and a pale yellow transparent ultraviolet curable composition ( 2) was prepared. The viscosity of the ultraviolet curable composition (2) thus obtained is 256 mPa · s (25
° C).

An optical disk was prepared in the same manner as in Example 1 except that the composition (2) was used instead of the composition (1), and the durability test was performed in the same manner. As a result, no corrosion was observed in the aluminum reflective film.

Example 3 80 parts of hydrogenated bisphenol A diglycidyl ether obtained in Example 1 and neopentyl glycol diglycidyl ether ("N" manufactured by Sakamoto Pharmaceutical Co., Ltd.)
PG-DGE ”low chlorine product, total chlorine content = 0.91% by weight)
20 parts, 0.5 part of a cationic photopolymerization initiator “UVI6990” (manufactured by Union Carbide) and a leveling agent “L”
0.2 parts of "-7604" (manufactured by Nippon Unicar) was mixed and dissolved at 60 ° C for 1 hour to prepare a pale yellow transparent ultraviolet-curable composition (3). The viscosity of the ultraviolet-curable composition (3) thus obtained was 295 mPa · s (25 ° C.).

An optical disk was prepared in the same manner as in Example 1 except that the composition (3) was used instead of the composition (1), and a durability test was performed in the same manner. As a result, no corrosion was observed in the aluminum reflective film.

Example 4 60 parts of hydrogenated bisphenol A diglycidyl ether obtained in Example 1 and bisphenol A diglycidyl ether (“Epiclon 1050” manufactured by Dainippon Ink and Chemicals, Ltd., total chlorine content = 0) 15 parts by weight), 30 parts of 1,6-hexanediol diglycidyl ether (“16H-DGE”, low chlorine product, total chlorine content = 0.49% by weight, manufactured by Sakamoto Pharmaceutical Co., Ltd.) and photocationic polymerization 0.5 parts of an initiator "UVI6990" (manufactured by Union Carbide) and 0.2 parts of a leveling agent "L-7604" (manufactured by Nippon Unicar) are mixed and dissolved at 60C for 1 hour,
A pale yellow transparent ultraviolet curable composition (4) was prepared. The viscosity of the ultraviolet-curable composition (4) thus obtained is:
244 mPa · s (25 ° C.).

An optical disk was prepared in the same manner as in Example 1 except that the composition (4) was used instead of the composition (1), and the durability test was performed in the same manner. As a result, no corrosion was observed in the aluminum reflective film.

<Example 5> In Example 1, instead of 0.5 parts of the cationic photopolymerization initiator "UVI6990",
Example 1 except that 1 part of "RHODORSIL PI2074" (4-methylphenyl-4- (1-methylethyl) phenyliodonium tetrakis (pentafluorophenyl) borate manufactured by Rhone Poulin) was used. Similarly, a pale yellow transparent ultraviolet ray curable composition (5) was prepared. The viscosity of the ultraviolet-curable composition (5) thus obtained was 230 mPa · s (25 ° C.).

An optical disk was prepared in the same manner as in Example 1 except that the composition (5) was used instead of the composition (1), and the durability test was performed in the same manner. As a result, no corrosion was observed in the aluminum reflective film.

<Example 6> A pale yellow, transparent yellowish transparent initiator was prepared in the same manner as in Example 1, except that the amount of the cationic photopolymerization initiator "UVI6990" was increased from 0.5 part to 1 part. An ultraviolet curable composition (6) was prepared. The viscosity of the ultraviolet-curable composition (6) thus obtained was 21
It was 8 mPa · s (25 ° C.).

Two DVD substrates having an aluminum reflective film formed thereon were prepared, and a radical polymerization type UV-curable composition “SD-” was formed on the reflective film of each substrate so that the film thickness after curing was 5 to 10 μm. 523 "(Dainippon Ink Chemical Industry Co., Ltd.)
Co., Ltd.) and using a metal halide lamp (with a cold mirror, lamp output 120 W / cm) at 400 mJ /
The protective coating layer was provided by curing by irradiating with ultraviolet rays of cm ² . Next, the above composition (6) was dropped in a ring shape on the inner peripheral side on the protective coat layer of one of the substrates, and a metal halide lamp (with a cold mirror, lamp output 1) was added thereto.
(20 W / cm) and 300 mJ / cm ² of ultraviolet rays. Next, the other substrate was overlaid with the protective coat layer inside, and the spin coater was used for 1,500 per second.
The composition was spread between the two substrates by spinning. The optical disk manufactured in this way is
As a result of performing a durability test for 96 hours in a thermo-hygrostat at 5 ° C. and a relative humidity (RH) of 95%, no corrosion was observed on the aluminum reflective film.

Further, two DVD substrates provided with a protective coat layer in the same manner as described above are prepared, and the composition (6) is formed on the protective coat layer of one of the substrates in a ring shape on the inner peripheral side. 100 mJ / d using a metal halide lamp (with a cold mirror, lamp output 120 W / cm).
Irradiated with ultraviolet light of cm ² . The other substrate was overlapped with the protective coat layer inside, and the composition was spread between the two substrates by rotating with a spin coater.
Next, an ultraviolet ray of 800 mJ / cm ² was applied to the outer peripheral end surface of the bonded optical disk using the lamp. The time required for the protruding adhesive to harden on the outer peripheral end surface of the optical disk manufactured in this way and to lose the tackiness by touching with a finger was 30 minutes.

Example 7 64 parts of hydrogenated bisphenol A diglycidyl ether obtained in Example 1 and 1,6-hexanediol diglycidyl ether ("16H-DGE" low chlorine product manufactured by Sakamoto Yakuhin Co., Ltd. 16 parts of 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 20 parts of photocationic polymerization initiator "UVI6990" (manufactured by Union Carbide) 1 Parts and 0.2 parts of a leveling agent “L-7604” (manufactured by Nippon Unicar) were mixed and dissolved at 60 ° C. for 1 hour to prepare a pale yellow transparent ultraviolet-curable composition (7). The viscosity of the ultraviolet-curable composition (7) thus obtained was 218.
mPa · s (25 ° C.).

An optical disk was prepared in the same manner as in Example 6 except that the composition (7) was used instead of the composition (6), and a durability test was performed in the same manner. As a result, no corrosion was observed in the aluminum reflective film. Further, the time required for the adhesive protruding from the outer peripheral end surface of the optical disk to become non-tacky was measured in the same manner as in Example 5, and the result was 4 minutes.

Comparative Example 1 Hydrogenated bisphenol A diglycidyl ether (“HBE-10” manufactured by Shin Nippon Rika Co., Ltd.)
0 ", total chlorine content = 4.5% by weight) 80 parts, 1,6-hexanediol diglycidyl ether (" SR16H "manufactured by Sakamoto Pharmaceutical Co., Ltd., total chlorine content = 6.7% by weight) 20 parts, Photocationic polymerization initiator “UVI6990” (manufactured by Union Carbide) 0.5 part and leveling agent “L-760”
0.2 part of 4 "(manufactured by Nippon Unicar Co., Ltd.) was mixed and dissolved at 60 ° C. for 1 hour to prepare a pale yellow transparent ultraviolet-curable composition (C1). The ultraviolet-curable composition (C
The viscosity of 1) was 415 mPa · s (25 ° C.).

An optical disk was prepared in the same manner as in Example 1 except that the composition (C1) was used instead of the composition (1), and a durability test was performed in the same manner. As a result, the aluminum reflective film was transparently transformed due to corrosion.

Comparative Example 2 In Comparative Example 1, “HBE-1” was used as hydrogenated bisphenol A diglycidyl ether.
"KRM-2408" (manufactured by Asahi Denka Co., Ltd.
Comparative Example 1 except that 80 parts of total chlorine content = 7% by weight) was used.
In the same manner as in the above, the pale yellow transparent ultraviolet curable composition (C
2) was prepared. The viscosity of the ultraviolet-curable composition (C2) thus obtained was 539 mPa · s (25 ° C.).

An optical disk was prepared in the same manner as in Example 1 except that the composition (C2) was used in place of the composition (1), and a durability test was performed in the same manner. As a result, the aluminum reflective film was transparently transformed due to corrosion.

Comparative Example 3 Hydrogenated bisphenol A diglycidyl ether ("HBE-10" manufactured by Shin Nippon Rika Co., Ltd.)
0 ", total chlorine content = 4.5% by weight) 80 parts, neopentyl glycol diglycidyl ether (" EX-211 "manufactured by Nagase Kasei Co., Ltd., total chlorine content = 5.7% by weight) 20 parts,
Photocationic polymerization initiator “UVI6990” (manufactured by Union Carbide) 0.5 part and leveling agent “L-760”
0.2 parts of 4 "(manufactured by Nippon Unicar Co., Ltd.) was mixed and dissolved at 60 ° C. for 1 hour to prepare a pale yellow transparent ultraviolet-curable composition (C3). The ultraviolet-curable composition (C
The viscosity of 3) was 448 mPa · s (25 ° C.).

An optical disk was prepared in the same manner as in Example 1 except that the composition (C3) was used instead of the composition (1), and a durability test was performed in the same manner. As a result, the aluminum reflective film was transparently transformed due to corrosion.

Comparative Example 4 Hydrogenated bisphenol A diglycidyl ether ("KRM-240" manufactured by Asahi Denka Co., Ltd.)
8 ", total chlorine content = 7% by weight) 100 parts, alicyclic polyfunctional epoxy resin having terminal hydroxyl group (" EH "manufactured by Daicel Corporation)
PE3150 ") 5 parts, cationic photopolymerization initiator" SP-
150 "(made by Asahi Denka Co., Ltd.), ion exchanger" IXE-
1320 "(manufactured by Toagosei Chemical Co., Ltd.) and 3 parts of finely divided silica were dissolved and mixed by heating to obtain a white, opaque, ultraviolet-curable composition (C4).

Two DVD substrates on which an aluminum reflective film was formed were prepared, and the composition (C4) was formed on the reflective film side of both substrates by an adhesive layer by screen printing. A metal halide lamp (with a cold mirror, a lamp output of 120 W / cm) is applied to the two substrates for 100
After irradiation with ultraviolet rays of mJ / cm ² , the adhesive layer was bonded. A 96-hour durability test was performed on the optical disk thus manufactured in a thermo-hygrostat at 85 ° C. and a relative humidity (RH) of 95%. As a result, it was found that the aluminum reflective film was transparently changed due to corrosion.

[0085]

When the ultraviolet-curable composition of the present invention is used as an adhesive for an optical disk, corrosion on a reflective film or a recording film made of a metal such as aluminum under a high-temperature and high-humidity condition is extremely small. Therefore, the ultraviolet-curable composition of the present invention is useful as an adhesive for a bonding optical disk such as a DVD having excellent long-term reliability.

Further, since the adhesive layer made of the ultraviolet-curable composition of the present invention is uniform and transparent, the ultraviolet-curable composition of the present invention can be used not only for DVD-RAM but also for one layer from one side of an optical disk. In addition to the DVD-5 method and the DVD-10 method for reading only information, the present invention can be applied to an adhesive layer in the DVD-9 method for reading two layers of information from one side.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kazuo Murakami 5-5-5-8- 407 Isehara-cho, Kawagoe-shi, Saitama

Claims (10)

[Claims] 1. An ultraviolet-curable composition used when two substrates having a recording layer are bonded together with the recording layer side inside, a glycidyl ether type epoxy resin composition (A), a cationic photopolymerization initiator An ultraviolet-curable composition containing (B) and having an amount of chlorine of 1% by weight or less in the epoxy resin composition (A). 2. The glycidyl ether type epoxy resin composition (A) is an epoxy resin composition comprising (A-1) bisphenol type diglycidyl ether and (A-2) aliphatic diol diglycidyl ether. The ultraviolet-curable composition according to the above. 3. The bisphenol-type diglycidyl ether (A-1) is hydrogenated bisphenol A diglycidyl ether, and the aliphatic diol diglycidyl ether (A-2) is propylene glycol diglycidyl ether or neopentyl glycol. Diglycidyl ether,
The ultraviolet-curable composition according to claim 2, wherein the composition is at least one compound selected from the group consisting of butanediol diglycidyl ether, hexanediol diglycidyl ether, and cyclohexanedimethanol diglycidyl ether. 4. The cationic photopolymerization initiator (B) whose cationic portion has an aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium and (2,4-cyclopentadien-1-yl) [( 1-methylethyl) benzene] -Fe cation, wherein the anion moiety is represented by the general formula [BX ₄ ] ^- (where
The ultraviolet-curable composition according to any one of claims 1 to 3, wherein X is an onium salt composed of at least two or more phenyl groups substituted with fluorine or a trifluoromethyl group. 5. The ultraviolet-curable composition according to claim 1, further comprising a compound (C) having an oxetane ring. 6. The optical disk according to claim 1, wherein the two substrates having a recording layer are bonded together with the recording layer side inside using an adhesive. An optical disc, which is a curable composition. 7. A method for manufacturing an optical disk in which two substrates having a recording layer are bonded using an adhesive with the recording layer side inside, wherein the adhesive is as set forth in any one of claims 1 to 5. Using an ultraviolet-curable composition of the above, while irradiating ultraviolet rays, the adhesive is dropped in a ring shape on the surface on the side to be bonded of at least one of the substrates, and then the two substrates are overlapped and then rotated at a high speed. A method for manufacturing an optical disk, comprising spreading the adhesive. 8. A method for manufacturing an optical disk, comprising bonding two substrates having a recording layer with the recording layer side inside using an adhesive, wherein the adhesive is any one of claims 1 to 5. Using the ultraviolet-curable composition described in the above, the adhesive was dropped in a ring shape on the surface to be bonded of the two substrates while irradiating the ultraviolet light, and then the two substrates were overlapped, and then self-weighted or pressed. A method for manufacturing an optical disc, wherein the adhesive is spread by the method. 9. A method for manufacturing an optical disk in which two substrates having a recording layer are bonded together with an adhesive with the recording layer side inside, wherein the adhesive according to claim 1 is used as the adhesive. By using the ultraviolet-curable composition described, the adhesive is dropped in a ring shape on the surface of at least one of the substrates to be bonded, irradiated with ultraviolet light, and then the two substrates are superimposed and rotated at a high speed. A method for manufacturing an optical disk, comprising spreading the adhesive. 10. A method for manufacturing an optical disk, comprising bonding two substrates having a recording layer with the recording layer side inside using an adhesive, wherein the adhesive is any one of claims 1 to 5. Using the ultraviolet-curable composition described, the adhesive is dropped in a ring shape on the surface to be bonded of the two substrates, and after irradiating both substrates with ultraviolet light, the two substrates are superimposed, and then self-weight or A method for manufacturing an optical disk, wherein the adhesive is spread by applying pressure.