JP2006179111A - Ultraviolet curable composition for optical disc and optical disc using the same - Google Patents

Abstract

（式中、Ｘは-SO₂-、-CH₂-、-CH(CH₃)-又は-C(CH₃)₂-、Ｙは式(2)

で表されるｍ個の基と、式(3)

で表されるｐ個の基とが、ランダムあるいはブロック状に連なった基を表す。但し、ｍは１〜１０の整数、ｐは０〜１０の整数である。）で表されるエポキシ樹脂（Ｂ）とを反応させて得られるエポキシアクリレート樹脂を含有する光ディスク用紫外線硬化型組成物。
【選択図】 なし
PROBLEM TO BE SOLVED: To be used for an optical disc having high adhesive strength on many surfaces such as polycarbonate, aluminum, silver alloy, gold, etc., and having excellent durability without deterioration of adhesive strength before and after being left in a high temperature and high humidity environment for a long time. An ultraviolet curable composition is provided.
A half ester compound (A) obtained from a hydroxyalkyl (meth) acrylate (a1) and a dibasic acid anhydride (a2), and a compound represented by the formula (1)

(Wherein X represents —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) ₂ —, Y represents formula (2)

M groups represented by the formula (3)

P groups represented by the above are groups that are connected in a random or block form. However, m is an integer of 1-10, p is an integer of 0-10. The ultraviolet curable composition for optical discs containing the epoxy acrylate resin obtained by making it react with the epoxy resin (B) represented by this.
[Selection figure] None

Description

  The present invention comprises an ultraviolet curable composition for optical discs and a reflective film for reflecting laser light for reading information on a substrate, and further a protective layer made of a cured film of the ultraviolet curable composition is provided on the reflective film. A bonded optical disk in which two substrates including a reflection film for reflecting information reading laser light are bonded to each other by a cured film of an ultraviolet curable composition. About.

There are various types of optical disks. For example, an information recording layer is formed on an optical disc in which a cured film of an ultraviolet curable resin composition for protecting the recording layer is formed on the information recording layer formed on the substrate, or at least one optical disc substrate There is a bonded optical disk in which the two substrates are bonded with a cured film of an ultraviolet curable resin composition.
An information recording layer is a layer made of an unevenness called a pit, a phase change material or a dye formed on an optical disk substrate made of a synthetic resin such as polycarbonate, and an information reading laser beam formed thereon. It is a laminate composed of a translucent reflection film or a complete reflection film for reflection. The semitransparent reflection film and the complete reflection film are layers formed on the uppermost part of the information recording layer, and are generally layers made of a metal or metal alloy thin film.

  A typical example of the bonded optical disk is a DVD (digital versatile disk or digital video disk). In particular, there are various types of read-only DVDs. For example, an optical disc called “DVD-10” is provided with irregularities called pits corresponding to recorded information on one surface of a substrate, and an aluminum layer, for example, is used as a layer for reflecting laser light for reading information. Two formed optical disk polycarbonate substrates are prepared and bonded together with an aluminum layer as an adhesive surface. “DVD-5” is obtained by bonding the substrate for manufacturing “DVD-10” and a normal transparent polycarbonate substrate not provided with an information recording layer. In addition, “DVD-9” is a substrate in which an aluminum reflective film is formed on a pit provided on one side of the substrate, and gold or an alloy containing gold as a main component, silver or silver on the pit provided on one side of the substrate. And a substrate on which a translucent reflective film made of an alloy or a silicon compound as a main component is formed and the reflective films are bonded together as an adhesive surface. Furthermore, “DVD-18” has a structure in which two substrates having two information recording layers on one side are bonded together. At present, “DVD-9”, which has a large recording capacity and can read information on two layers from one side, has become the mainstream.

  As the translucent reflective film such as DVD-9, gold or a silicon compound is mainly used. However, gold is disadvantageous in that the material is very expensive and disadvantageous in terms of cost, and silicon compounds are very difficult to form. Therefore, replacement with silver or an alloy containing silver as a main component has been actively studied because it is cheaper and easier to form than gold.

  Furthermore, DVDs can be broadly classified into read-only types and recordable types. In recordable DVDs, write-once DVD-R and DVD + R methods and rewritable DVD-RW, DVD + RW and DVD-RAM methods are available. is there. Among these DVDs, DVDs called write-once type DVD-R and DVD + R are different from other DVDs in that organic dyes are used in the recording layer. In a write-once optical disc, a recording layer is formed on a transparent substrate by irreversibly changing optical characteristics or forming a concavo-convex shape by laser light irradiation. As the recording layer, for example, a cyanine-based, phthalocyanine-based, or azo-based organic dye that is decomposed by heating by laser light irradiation, changes its optical constant, and causes deformation of the substrate by volume change is used.

  Many of these methods have been developed, but an ultraviolet curable composition for forming a resin layer provided on an information recording layer is used for optical discs using various recording methods developed one after another. Yes.

  By the way, the characteristic of such an optical disk is greatly influenced by the characteristic of the ultraviolet curable composition for forming the resin layer provided on an information recording layer. For example, an ultraviolet curable composition used for a bonded optical disc is required to exhibit excellent adhesion to various materials forming an information recording surface. In other words, the adherend to which the ultraviolet curable composition for optical disks is bonded includes polycarbonate, aluminum, gold, gold alloy, silver, silver alloy, silicon compound, organic dye, etc., which are excellent for all of them. It is required to show a high adhesive strength.

  As an ultraviolet curable composition used for a bonded optical disk, a half ester compound which is a reaction product of (meth) acrylate and dibasic acid anhydride containing one hydroxyl group in one molecule and one molecule. Techniques relating to an ultraviolet curable adhesive composition for laminating optical disks containing a reaction product of an epoxy resin having at least two epoxy groups, a reactive diluent, and a photopolymerization initiator are disclosed (for example, Patent Documents). 1). This technique aims to provide an adhesive composition having high durability (reliability) in a bonded optical disc having a translucent reflective film made of silver or the like, and is in an environment of 80 ° C. and 85% RH. It has been reported that the appearance of the reflective film does not change even after being left for 500 hours. However, when the composition of the example described in the art, that is, the ultraviolet curable composition containing a reaction product of 2-acryloyloxyethyl phthalate and a bisphenol A type epoxy resin, is examined in detail, the initial adhesive strength In addition, the adhesive strength decreased after being left in a high-temperature and high-humidity environment for a long time, and an increase in signal reading error was recognized, and it was found that further improvement was necessary in practice.

  On the other hand, an active energy ray-curable type containing, as essential components, an epoxy acrylate resin obtained by reacting a lactone adduct of hydroxyalkyl (meth) acrylate, a dicarboxylic acid anhydride and an epoxy resin, and a radical polymerizable monomer A technique relating to a coating composition is known (for example, see Patent Document 2). This technique mainly aims at a wood coating material for obtaining a cured coating film having high hardness and elongation that suppresses the occurrence of cracks. Further, it contains an epoxy (meth) acrylate obtained by reacting a hydroxy group-containing (meth) acrylate, an acid anhydride, and a bifunctional or higher epoxy resin, and a (meth) acryloyl group-containing compound added as necessary. A technique relating to an active energy ray-curable optical fiber coating resin composition is known (see, for example, Patent Document 3). The technique aims to provide an active energy ray-curable optical fiber coating resin composition having a high curing speed and a cured product having heat and moisture resistance and low hygroscopicity suitable for optical fiber coating. However, these documents do not describe anything about the ultraviolet curable composition used for optical discs and the technology relating to optical discs using the same, and particularly the adhesive strength before and after being left for a long time in a high temperature and high humidity environment. No mention is made of an ultraviolet curable composition used for an optical disc that suppresses a decrease and signal reading error, and an optical disc using the composition.

JP 2003-206449 A (Claims, fourth paragraph, examples) JP 2003-105230 A (claims, fifth paragraph, examples) JP 2004-51905 A (claims, fifth paragraph, examples)

  Therefore, the object of the present invention is to have high adhesive strength on many surfaces such as polycarbonate, aluminum, silver alloy, gold, etc., and to improve durability without lowering the adhesive strength before and after being left in a high temperature and high humidity environment for a long time. An object of the present invention is to provide an ultraviolet curable composition used for an excellent optical disc and an optical disc using the same.

  Conventionally, in order to improve the adhesion between the information recording surface of the optical disk substrate and the cured film of the ultraviolet curable composition, the shrinkage rate when the ultraviolet curable composition is cured is reduced, or the film after curing is It has been found that it is effective to reduce or alleviate the strain at the time of curing by lowering the elastic modulus. As a means for that purpose, attempts have been made to increase the use ratio of relatively high molecular weight oligomers and keep the use ratio of low molecular weight monomers low.

  In order to solve the problems of the present invention, the present inventors have been widely used in the field of coating agents and adhesives, and are generally used in UV curable compositions for optical discs. An ultraviolet curable composition containing the above was studied. However, bisphenol A type epoxy acrylate has a high viscosity, and therefore it is difficult to use a large amount of the compound in order to keep the coating performance constant, and the composition using the compound is cured after curing. The elastic modulus of the film becomes high, and the distortion at the time of curing is not alleviated. For this reason, problems such as signal reading errors and appearance defects are likely to occur. Further, it has been found that when exposed to a high temperature and high humidity environment for a long time, distortion upon curing due to heat and moisture further expands on the surface of the recording layer, causing an increase in signal reading errors and appearance defects.

  Therefore, an ultraviolet curable composition containing a reaction product of 2-acryloyloxyethyl phthalate and a bisphenol A type epoxy resin described in Examples of Patent Document 1 was examined. The ultraviolet curable composition containing the reaction product did not increase in viscosity so as to impair the coating performance even if the reaction product was contained in a large amount. However, the cured film of the ultraviolet curable composition containing the reaction product has a low initial adhesive force to the information recording surface of the optical disk substrate, and a decrease in the adhesive force after being left in a high temperature and high humidity environment for a long time. Happens. This is presumed to be because the cured film of the ultraviolet curable composition containing the reactant has a high elastic modulus, and therefore, distortion generated during curing is not alleviated.

  Based on the above results, the present inventors examined an oligomer having a molecular structure that can relieve the strain generated during curing. As a result, the half ester compound (A) obtained from the hydroxyalkyl (meth) acrylate (a1) and the dibasic acid anhydride (a2) is reacted with the epoxy resin (B) represented by the following formula (1). The epoxy acrylate resin thus obtained was found to have the desired characteristics, and the present invention was completed.

  That is, the present invention relates to a half ester compound (A) obtained from a hydroxyalkyl (meth) acrylate (a1) and a dibasic acid anhydride (a2), a compound represented by the formula (1)

（式中、Ｘは-SO₂-、-CH₂-、-CH(CH₃)-又は-C(CH₃)₂-、Ｙは式(2)

(Wherein X represents —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) ₂ —, Y represents formula (2)

（式中、Ｒ^１は分岐鎖を有していても良い炭素数２〜１０のアルキレン基、Ｘは-SO₂-、-CH₂-、-CH(CH₃)-又は-C(CH₃)₂-、ｎは１〜１０の整数を表す。）で表されるｍ個の基と、式(3)

Wherein R ¹ is an alkylene group having 2 to 10 carbon atoms which may have a branched chain, and X is —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) _2- , n represents an integer of 1 to 10) and m groups represented by formula (3)

（式中、Ｘは-SO₂-、-CH₂-、-CH(CH₃)-又は-C(CH₃)₂-を表す。）で表されるｐ個の基とが、ランダムあるいはブロック状に連なった基を表す。但し、ｍは１〜１０の整数、ｐは０〜１０の整数である。）で表されるエポキシ樹脂（Ｂ）とを反応させて得られるエポキシアクリレート樹脂を含有する光ディスク用紫外線硬化型組成物を提供するものである。

(Wherein X represents —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) ₂ —), and p groups represented by a random or block Represents a group connected in a shape. However, m is an integer of 1-10, p is an integer of 0-10. The ultraviolet curable composition for optical discs containing the epoxy acrylate resin obtained by making it react with the epoxy resin (B) represented by this is provided.

  The present invention further comprises a first reflective film for reflecting information reading laser light on the first substrate, and further comprising a cured film of an ultraviolet curable composition on the first reflective film. An optical disc provided with a resin layer, and an optical disc using the above-mentioned ultraviolet curable composition as the ultraviolet curable composition.

  The cured film of the ultraviolet curable composition of the present invention has a high initial adhesive force to the information recording surface of the optical disk substrate, and does not cause a decrease in the adhesive force even after being left in a high temperature and high humidity environment for a long time. .

  In this specification, the reflective film is a translucent reflective film for reflecting laser light for reading information or a completely reflective film that does not substantially transmit the laser light, and (meth) acrylic acid is Acrylic acid or methacrylic acid, and the same applies to derivatives of acrylic acid or methacrylic acid.

The ultraviolet curable composition of this invention contains the said epoxy acrylate resin. The epoxy acrylate resin is preferably produced by the following reaction process.
As the first stage reaction, the hydroxyl ratio of the hydroxyalkyl (meth) acrylate (a1) and the dibasic acid anhydride (a2) are mixed, and the molar ratio of the hydroxyl group of (a1) to the dibasic acid anhydride (a2) is 0. The reaction is carried out in an amount of from 1.9 to 1.1, preferably equimolar to obtain the half ester compound (A).
As the second stage reaction, the obtained half ester compound (A) and the epoxy resin (B) represented by the formula (1) are mixed with the carboxyl group of the half ester compound (A) and the glycidyl of the epoxy resin (B). The groups are reacted in a molar ratio of 0.9 to 1.1, preferably equimolar.

  The first stage reaction is desirably carried out in the presence of an inhibitor at a reaction temperature of 60 to 120 ° C, preferably 70 to 100 ° C. Below 60 ° C, the reaction time becomes long, and above 120 ° C, polymerization of unsaturated double bonds of hydroxyalkyl (meth) acrylate (a1) tends to occur. In the second stage reaction, the reaction time becomes longer at 60 ° C. or lower, and the polymerization of unsaturated double bonds between the hydroxyalkyl (meth) acrylate and the acid anhydride half ester (A) tends to occur at 120 ° C. or higher. In the presence of an inhibitor, it is desirable to react at a reaction temperature of 60 to 120 ° C, preferably 70 to 100 ° C. Any known catalyst can be used as the ring-opening catalyst for the glycidyl group. Representative examples include tertiary amines such as triethylenediamine and tri-n-butylamine, phosphines such as triphenyl phosphite, phosphite, and triphenylphosphine.

  Examples of the hydroxyalkyl (meth) acrylate (a1) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like. Alternatively, a hydroxyalkyl (meth) acrylate lactone adduct obtained by ring-opening addition of a lactone compound to the exemplified hydroxyalkyl (meth) acrylate may be used. Examples of the lactone compound include β-propiolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, β-methyl-δ-valerolactone, γ-caprolactone, and ε-caprolactone. .

  The weight average molecular weight (Mw) of the epoxy acrylate resin is preferably 900 to 8000, and more preferably 1200 to 3000. Further, the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is preferably 1.3 to 2.8, more preferably 1.4 to 2.0. . When the weight average molecular weight (Mw) and (Mw / Mn) are in the above ranges, the viscosity of the epoxy acrylate resin is low, and the concentration of the epoxy acrylate resin (oligomer) as the ultraviolet curable composition can be increased. The bond concentration can be lowered, and as a result, distortion due to curing shrinkage of the cured coating film is reduced, which is preferable.

  Examples of the dibasic acid anhydride (a2) include phthalic anhydride, 1,2,3,6 tetrahydrophthalic anhydride and derivatives thereof, 3,4,5,6-tetrahydrophthalic anhydride and derivatives thereof, 2,3,4-tetrahydrophthalic anhydride and derivatives thereof, 2,3,4,5-tetrahydrophthalic anhydride and derivatives thereof, hexahydrophthalic anhydride and derivatives thereof, succinic anhydride and derivatives thereof Monoalkyl succinic anhydride and derivatives thereof, dialkyl succinic anhydride and derivatives thereof, maleic anhydride and derivatives thereof, monoalkyl maleic anhydride and derivatives thereof, and dialkyl maleic anhydride and derivatives thereof. Of these, phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride are preferably used.

As the epoxy resin (B), a compound represented by the formula (1) is used, and among them, a bisphenol A type epoxy resin in which X in the formula is —C (CH ₃ ) ₂ — is adhesive strength, It is excellent in performance and cost such as durability and is preferable.

（式中、Ｘは-SO₂-、-CH₂-、-CH(CH₃)-又は-C(CH₃)₂-、Ｙは式(2)

(Wherein X represents —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) ₂ —, Y represents formula (2)

（式中、Ｒ^１は分岐鎖を有していても良い炭素数２〜１０のアルキレン基、Ｘは-SO₂-、-CH₂-、-CH(CH₃)-又は-C(CH₃)₂-、ｎは１〜１３の整数を表す。）で表されるｍ個の基と、式(3)

Wherein R ¹ is an alkylene group having 2 to 10 carbon atoms which may have a branched chain, and X is —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) _2- , n represents an integer of 1 to 13, and m groups represented by formula (3)

（式中、Ｘは-SO₂-、-CH₂-、-CH(CH₃)-又は-C(CH₃)₂-を表す。）で表されるｐ個の基とが、ランダムあるいはブロック状に連なった基を表す。但し、ｍは１〜１０の整数、ｐは０〜１０の整数である。）

(Wherein X represents —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) ₂ —), and p groups represented by a random or block Represents a group connected in a shape. However, m is an integer of 1-10, p is an integer of 0-10. )

Further, R ¹ in the formula (2) is preferably an alkylene group having 2 to 6 carbon atoms, and more preferably — (CH ₂ ) ₅ —. Furthermore, n in the formula (2) is preferably 2 to 10, and more preferably 3 to 6. m is preferably from 1 to 4, and more preferably from 1 to 2. And it is preferable that p is 0-3, and it is more preferable that it is 0-1.

  In the ultraviolet curable composition of the present invention, a half ester compound (A) obtained from hydroxyalkyl (meth) acrylate (a1) and dibasic acid anhydride (a2), and an epoxy represented by the formula (1) It is preferable to contain 10-90 mass% of epoxy acrylate resin obtained by making resin (B) react, and it is preferable to contain 20-70 mass% with respect to the whole ultraviolet curable composition. Further, known radical polymerizable monomers, oligomers, photopolymerization initiators, thermal polymerization initiators, and the like can be used in the ultraviolet curable composition.

  Examples of radically polymerizable monomers include, for example, monofunctional (meth) acrylates such as ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, hexadecyl (Meth) acrylate, octadecyl (meth) acrylate, isoamyl (meth) acrylate, isodecyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate , 3-chloro-2-hydroxypropyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, nonylphenoxyethyl (meth) acrylate Relate, tetrahydrofurfuryl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, nonylphenoxyethyl tetrahydrofurfuryl (meth) acrylate, caprolactone modified tetrahydrofurfuryl (meth) acrylate, etc. Can be mentioned.

  Examples of the polyfunctional (meth) acrylate include 1,4-butanediol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate. , Neopentyl glycol di (meth) acrylate, 2-methyl-1,8-octanediol di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, ethylene glycol di (meth) Polyoxyalkyl ether (meth) polyacrylates such as acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate; Lunan dimethanol diacrylate, norbornane diethanol di (meth) acrylate, di (meth) acrylate of diol obtained by adding 2 moles of ethylene oxide or propylene oxide to norbornane dimethanol, tricyclodecane dimethanol di (meth) acrylate, tri Cyclodecanediethanol di (meth) acrylate, di (meth) acrylate of diol obtained by adding 2 moles of ethylene oxide or propylene oxide to tricyclodecanedimethanol, pentacyclopentadecanedimethanol di (meth) acrylate, pentacyclopentadecanediethanol Di (meth) acrylate and pentacyclopentadecane dimethanol are added with 2 moles of ethylene oxide or propylene oxide. ) Monomers having an alicyclic structure such as di (meth) acrylate of diol obtained by adding 2 mol of ethylene oxide or propylene oxide to acrylate, pentacyclopentadecane diethanol; trimethylolpropane tri (meth) acrylate, pentaerythritol tri (Meth) acrylate, bis (2-acryloyloxyethyl) hydroxyethyl isocyanurate, bis (2-acryloyloxypropyl) hydroxypropyl isocyanurate, bis (2-acryloyloxybutyl) hydroxybutyl isocyanurate, bis (2-methacryloyloxy) Ethyl) hydroxyethyl isocyanurate, bis (2-methacryloyloxypropyl) hydroxypropyl isocyanurate, bis (2-methacryloyloxy) Butyl) hydroxybutyl isocyanurate, tris (2-acryloyloxyethyl) isocyanurate, tris (2-acryloyloxypropyl) isocyanurate, tris (2-acryloyloxybutyl) isocyanurate, tris (2-methacryloyloxyethyl) isocyanurate , Monomers having an isocyanurate structure such as tris (2-methacryloyloxypropyl) isocyanurate, tris (2-methacryloyloxybutyl) isocyanurate, poly (meth) acrylates of dipentaerythritol, ethylene oxide-modified phosphoric acid (meth) ) Acrylate, ethylene oxide modified alkylated phosphoric acid (meth) acrylate, diethylaminoethyl (meth) acrylate, N-vinylpyrrolidone, N-vinylcapro A lactam, a vinyl ether monomer, etc. can be mentioned, The 1 type (s) or 2 or more types of the said radically polymerizable unsaturated monomer can be used.

  As an oligomer that can be used in the present invention, for example, polyurethane (meth) acrylate such as urethane (meth) acrylate of polyether skeleton, urethane (meth) acrylate of polyester skeleton, urethane (meth) acrylate of polycarbonate skeleton, or Active energy ray-curable oligomers such as polyester (meth) acrylate obtained by esterifying (meth) acrylic acid to polyol of polyester skeleton, and polyether (meth) acrylate obtained by esterifying (meth) acrylic acid to polyol of polyether skeleton 1 type or 2 types or more can be used.

  As the photopolymerization initiator, any known and commonly used photopolymerization initiators can be used, but those of molecular cleavage type or hydrogen abstraction type are suitable as the photopolymerization initiator used in the present invention. Examples of the photopolymerization initiator used in the present invention include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzyl, 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyldimethyl ketal, 2-hydroxy 2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- (4-methylthiophenyl) -2 -Use a molecular cleavage type such as morpholinopropan-1-one, or a hydrogen abstraction type photopolymerization initiator such as benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4'-methyl-diphenyl sulfide. Can do.

  Examples of sensitizers include trimethylamine, methyldimethanolamine, triethanolamine, p-dimethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzylamine and 4,4′-bis (diethylamino) benzophenone or the like can be used, and further, an amine that does not cause an addition reaction with the photopolymerizable compound can be used in combination. Of course, it is preferable to select and use those which are excellent in solubility in the ultraviolet curable compound and do not inhibit the ultraviolet transmittance. In addition, in the ultraviolet curable resin composition, as necessary, surfactants, leveling agents, thermal polymerization inhibitors, antioxidants such as hindered phenols and phosphites, and light stabilizers such as hindered amines are added as necessary. Can also be used

  In the ultraviolet curable composition of the present invention, it is preferable to add a compound represented by the formula (4). By adding the compound represented by the formula (4), the initial adhesive force of the cured film of the ultraviolet curable composition can be further increased, and further, after the optical disk is left in a high temperature and high humidity environment for a long time. It is possible to prevent a considerable decrease in the adhesive strength, the change in the appearance of the reflective film, and the increase in signal reading errors.

（式中、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶はそれぞれ独立的に、(i)水素原子、(ii)ハロゲン原子、(iii)水酸基、(iv)炭素数１〜８のアルコキシル基、(v)カルボキシル基、(vi)式(5)

(Wherein R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently (i) a hydrogen atom, (ii) a halogen atom, (iii) a hydroxyl group, or (iv) a carbon number of 1-8). Alkoxyl group, (v) carboxyl group, (vi) formula (5)

（式中、Ｒ⁷は、ハロゲン原子で置換されていても良い炭素数１〜２０のアルキル基又はハロゲン原子で置換されていても良い炭素数１〜２０のアルケニル基を表す。）で表される基、或いは(vii)置換基としてカルボキシル基、アルコキシカルボニル基、アシルオキシル基又はアルコキシル基を有していても良い炭素数１〜２４のアルキル基若しくはアルケニル基を表すが、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶の中の少なくともひとつは水酸基である。）

(Wherein R ⁷ represents an alkyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom or an alkenyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom). Or (vii) a C1-C24 alkyl group or alkenyl group which may have a carboxyl group, an alkoxycarbonyl group, an acyloxyl group or an alkoxyl group as a substituent, R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are hydroxyl groups. )

  The compound represented by the formula (4) includes compounds having various structures, and among them, compounds represented by the following formula (6), formula (7), formula (8) and formula (9) are preferable.

（式中、Ｒ⁸は、水素原子、ハロゲン原子で置換されていても良い炭素数１〜２０のアルキル基又はハロゲン原子で置換されていても良い炭素数１〜２０のアルケニル基を表す。）

(In the formula, R ⁸ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom, or an alkenyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom.)

（式中、Ｒ⁹、Ｒ¹⁰、Ｒ¹¹及びＲ¹²はそれぞれ独立的に、水素原子、ハロゲン原子、炭素数１〜８のアルコキシル基、置換基として-COOH、-COOR¹³、-OCOR¹⁴又は-OR¹⁵を有していても良い炭素数１〜２４のアルキル基、或いは置換基として-COOH、-COOR¹³、-OCOR¹⁴又は-OR¹⁵を有していても良い炭素数１〜２４のアルケニル基を表す（式中、Ｒ¹³、Ｒ¹⁴、及びＲ¹⁵はそれぞれ独立的に、炭素数１〜８のアルキル基又は炭素数１〜８のアルケニル基を表す。）。）

(Wherein R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹³ , —OCOR ¹⁴ or An alkyl group having 1 to 24 carbon atoms which may have -OR ¹⁵ , or a 1 to 24 carbon atom which may have -COOH, -COOR ¹³ , -OCOR ¹⁴ or -OR ¹⁵ as a substituent; Represents an alkenyl group (wherein R ¹³ , R ¹⁴ and R ¹⁵ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms).

（式中、Ｒ¹⁶、Ｒ¹⁷、Ｒ¹⁸及びＲ¹⁹はそれぞれ独立的に、水素原子、ハロゲン原子、炭素数１〜８のアルコキシル基、置換基として-COOH、-COOR¹³、-OCOR¹⁴又は-OR¹⁵を有していても良い炭素数１〜２４のアルキル基、或いは置換基として-COOH、-COOR¹³、-OCOR¹⁴又は-OR¹⁵を有していても良い炭素数１〜２４のアルケニル基を表す（式中、Ｒ¹³、Ｒ¹⁴、及びＲ¹⁵はそれぞれ独立的に、炭素数１〜８のアルキル基又は炭素数１〜８のアルケニル基を表す。）。）

(Wherein R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹³ , —OCOR ¹⁴ or An alkyl group having 1 to 24 carbon atoms which may have -OR ¹⁵ , or a 1 to 24 carbon atom which may have -COOH, -COOR ¹³ , -OCOR ¹⁴ or -OR ¹⁵ as a substituent. Represents an alkenyl group (wherein R ¹³ , R ¹⁴ and R ¹⁵ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms).

（式中、Ｒ²⁰、Ｒ²¹、Ｒ²²及びＲ²³はそれぞれ独立的に、水素原子、ハロゲン原子、炭素数１〜８のアルコキシル基、置換基として-COOH、-COOR¹³、-OCOR¹⁴又は-OR¹⁵を有していても良い炭素数１〜２４のアルキル基、或いは置換基として-COOH、-COOR¹³、-OCOR¹⁴又は-OR¹⁵を有していても良い炭素数１〜２４のアルケニル基を表す（式中、Ｒ¹³、Ｒ¹⁴、及びＲ¹⁵はそれぞれ独立的に、炭素数１〜８のアルキル基又は炭素数１〜８のアルケニル基を表す。）。）

(Wherein R ²⁰ , R ²¹ , R ²² and R ²³ are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹³ , —OCOR ¹⁴ or An alkyl group having 1 to 24 carbon atoms which may have -OR ¹⁵ , or a 1 to 24 carbon atom which may have -COOH, -COOR ¹³ , -OCOR ¹⁴ or -OR ¹⁵ as a substituent; Represents an alkenyl group (wherein R ¹³ , R ¹⁴ and R ¹⁵ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms).

The alkyl group and alkenyl group in the above formula (6) may be branched or linear, and the halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Among them, R ⁸ is preferably a hydrogen atom or an alkyl group which may have an unsubstituted branched chain having 1 to 20 carbon atoms, and a hydrogen atom or an unsubstituted branched chain having 1 to 8 carbon atoms. It is more preferable that it is the alkyl group which may have. Furthermore, a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms is particularly preferable.

  As the gallic acid ester represented by the above formula (6), specifically, methyl gallate, ethyl gallate, propyl gallate, isopropyl gallate, isopentyl gallate, octyl gallate, dodecyl gallate, gallic acid Tetradecyl, hexadecyl gallate, octadecyl gallate and the like. As the compound represented by the formula (6), gallic acid is preferably used. Gallic acid is readily available as a commercial product, for example, manufactured by Dainippon Pharmaceutical Co., Ltd.

In formula (7), R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are specifically, (i) a hydrogen atom, (ii) a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, ( iii) alkoxyl groups such as methoxy, ethoxy, butoxy and octyloxy; (iv) alkyl groups such as methyl, butyl, hexyl, octyl, lauryl and octadecyl; (v) alkenyl groups such as ethenyl, propenyl and 2-butenyl; ) 4-carboxybutyl, 2-methoxycarbonylethyl, methoxymethyl, ethoxymethyl and the like.

  Among the compounds represented by the formula (7), catechol, 3-sec-butylcatechol, 3-tert-butylcatechol, 4-sec-butylcatechol, 4-tert-butylcatechol, 3,5-di- -Tert-butylcatechol, 3-sec-butyl-4-tert-butylcatechol, 3-tert-butyl-5-sec-butylcatechol, 4-octylcatechol and 4-stearylcatechol, more preferably catechol And 4-tert-butylcatechol. It is particularly preferable to use 4-tert-butylcatechol. Examples of commercially available 4-tert-butylcatechol include DIC TBC-5P manufactured by Dainippon Ink and Chemicals, Inc.

R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ in the formula (8) and R ²⁰ , R ²¹ , R ²² and R ²³ in the formula (9) are specifically a hydrogen atom, a methyl group, Examples include propyl group, hexyl group, nonyl group, dodecyl group, iso-butyl group, sec-butyl group, tert-butyl group, neopentyl group, iso-hexyl group, tert-octyl group and the like.

  Among the compounds represented by the formula (8), hydroquinone, 2-hydroxyhydroquinone, 2,5-di-tert-butylhydroquinone, 2,5-bis (1,1,3,3-tetramethyl) are preferable. Butyl) hydroquinone or 2,5-bis (1,1-dimethylbutyl) hydroquinone. Of the compounds represented by the formula (8), resorcinol (benzene-1,3-diol) and orcinol (5-methylbenzene-1,3-diol) are preferred. Among the compounds represented by the formula (8), it is more preferable to use hydroquinone (benzene-1,4-diol) or 2-hydroxyhydroquinone (benzene-1,2,4-triol). Another compound that is preferably used in the present invention as the compound represented by the formula (4) is pyrogallol (1,2,3-trihydroxybenzene).

  Among the compounds represented by the above formulas (6) to (9), the gallic acid or gallic acid ester represented by the formula (6) and the hydroquinone compound represented by the formula (8) are high temperature and high humidity. It is a particularly preferred compound among the compounds represented by the formula (4) because it can particularly improve durability in the environment. Of the compounds represented by formula (4), gallic acid is the most preferred compound.

  The amount of the compound represented by the formula (4) added to the ultraviolet curable composition is preferably 0.05 to 10% by mass, more preferably 0.8%, based on the entire active energy ray curable composition. 1 to 10% by mass. It is still more preferable that it is 0.3-7 mass%, and it is especially preferable that it is 1-5 mass parts.

  An optical disk using the ultraviolet curable composition of the present invention comprises a first reflective film for reflecting laser light for reading information on a first substrate, and the ultraviolet light is further formed on the first reflective film. An optical disk having a structure provided with a resin layer made of a cured film of a curable composition. An optical disk using the ultraviolet curable composition of the present invention is an optical disk having such a structure or an optical disk partially having such a structure. As such an optical disk, for example, a thin film of silver or a silver-based alloy is used as a light reflecting layer, and a resin layer made of a cured film of an ultraviolet curable composition is provided as a protective layer on the light reflecting layer. CD-ROM or CD-R is available. Further, for example, there is a DVD-5 in which a substrate having a light reflection layer made of silver or a silver-based alloy thin film is bonded to another substrate with an ultraviolet curable composition using the light reflection layer as an adhesive surface. is there.

  An optical disk using the ultraviolet curable composition of the present invention is further provided with a laser beam for reading information on a resin layer made of the cured film of the ultraviolet curable composition provided on the first reflective film. Even if the second substrate provided with the second reflective film for reflecting light is an optical disk having a structure provided on the resin layer so that the resin layer and the second reflective film are in contact with each other good. As an optical disk having such a structure, at least one of two optical disk substrates provided with a reflective film for reflecting laser light for reading information has, for example, silver or silver as a main component on its surface. A bonding type of DVD-9, DVD-18, DVD-10, etc., in which the two optical disk substrates are bonded with the reflection films of the two substrates as the bonding surfaces. There is an optical disc.

As the optical disk substrate, those usually used as optical disk substrates can be used, and in particular, a polycarbonate substrate can be suitably used. Various materials can be used as the reflective film for reflecting the laser beam for reading information. For example, aluminum, gold, gold alloy, silver, silver alloy, silicon compound, etc. can be used. Among them, it is preferable to use silver or an alloy containing silver as a main component for the optical disk of the present invention. Examples of the “alloy containing silver as a main component” used in optical disks include silver alloys having a silver to gold ratio (Ag _X Au _Y ) described in US Pat. It is done.
0.9 <x <0.999
0.001 ≦ _Y ≦ 0.10

  The type of the optical disk is preferably a read-only DVD “DVD-5”, “DVD-10”, “DVD-9” and “DVD-18”, writable DVD-R, DVD + R, rewritable type DVD-RW, DVD + RW, DVD-RAM, and the like, particularly preferably “DVD-9” and “DVD-18”.

  Further, the optical disk using the ultraviolet curable composition of the present invention is not limited to these. For example, on an optical disk substrate having a thickness of about 1.1 mm, for example, on a thin film of silver or a silver-based alloy as a main component. , A protective layer or cover layer or light transmission layer having a thickness of about 0.1 mm formed by a cured film of the composition, that is, a type suitable for blue-violet laser light as laser light for reading and writing information Alternatively, it may be a SACD (super audio CD) having a structure in which two substrates having a thickness of 0.6 mm, which are similar to those of a DVD, are bonded together.

  Hereinafter, examples of manufacturing “DVD-5”, “DVD-10”, “DVD-9”, and “DVD-18” will be described. Examples of the optical disk using the ultraviolet curable composition of the present invention are not limited to these. Further, the ultraviolet curable composition used in the following production examples means an ultraviolet curable composition containing the compound represented by the above formula (1) used in the present invention.

(Production of DVD-9)
One optical disk substrate (A: second substrate) in which a metal thin film (second reflective film) of 40 to 60 nm is laminated on the unevenness called pits carrying recording information, and called pits carrying recording information A substrate for optical disk (B: first substrate) 1 in which a semi-transparent reflective film (semi-transparent reflective film: first reflective film) of 10 to 30 nm of silver or an alloy containing silver as a main component is laminated on unevenness. Prepare a sheet.

  As the second reflective film, for example, a film mainly composed of aluminum, silver, or an alloy composed mainly of silver can be used. Further, as the optical disk substrate, those known as optical disk substrates can be used. For example, amorphous polyolefin, polymethyl methacrylate, polycarbonate and the like can be mentioned, and it is particularly preferable to use a polycarbonate substrate.

  Next, the ultraviolet curable composition was applied onto the metal thin film (second reflective film) of the substrate (A: second substrate), and a translucent reflective film (first reflective film) was further laminated. UV curing applied to the surface of the metal thin film (second reflection film) so that the film surface of the semi-transparent reflection film (first reflection film) is an adhesive surface of the substrate (B: first substrate). It is bonded to a substrate (A: second substrate) through a mold composition, and ultraviolet light is irradiated from one or both surfaces of the bonded two substrates to bond them to make “DVD-9”.

(Manufacture of DVD-18)
Further, after manufacturing the DVD-9, the metal thin film (second reflective film) formed on the substrate (A: second substrate) is left on the substrate (B: first substrate) side. By peeling only the substrate (A: second substrate), the substrate (B: first substrate) / translucent reflective film (first reflective film) / cured film of the ultraviolet curable composition / metal thin film A disk intermediate body in which (second reflective film) is sequentially laminated is produced. Two such disk intermediates are prepared. Next, by using the metal thin film (first reflective film) of the two disc intermediates as an adhesive surface, and bonding them so that they face each other, “DVD-18” is obtained.

(Production of DVD-10)
A second substrate for an optical disk (C1: first substrate) and (C2) in which a reflection film of 40 to 60 nm made of silver or an alloy containing silver as a main component is laminated on irregularities called pits that carry recording information. : A second substrate). An ultraviolet curable composition is applied on the reflective film (first reflective film) of one substrate (C1: first substrate), and the other substrate (C2: second substrate) is applied to the reflective film (second substrate). Substrate (C1: first substrate) via the composition applied to the reflective film (first reflector film) surface of the substrate (C1: first substrate) so that the film surface of the reflector film becomes an adhesive surface. 1 substrate), and ultraviolet rays are irradiated from one or both surfaces of the two bonded substrates to bond them together to make “DVD-10”.

(Production of DVD-5)
An optical disk substrate (D: first substrate) is prepared in which a first reflective film having a thickness of 40 to 60 nm made of silver or an alloy containing silver as a main component is laminated on irregularities called pits that carry recording information. Separately, an optical disk substrate (E) having no pits is prepared. An ultraviolet curable composition is applied onto the first reflective film of the substrate (D: first substrate), and the substrate (D: first substrate) and the substrate (E) are bonded together via the composition. Then, ultraviolet rays are irradiated from one or both surfaces of the two bonded substrates to bond them together to make “DVD-5”.

  The ultraviolet irradiation can be performed by a continuous light irradiation method using, for example, a metal halide lamp, a high pressure mercury lamp, or the like, or by a flash light irradiation method described in US Pat. No. 5,904,795. The flash irradiation method is more preferable in that it can be cured efficiently.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to these Examples.

<Synthesis Example-1>
Add 114 parts of 2-hydroxyethyl acrylate, 145 parts of phthalic anhydride, and 3 parts of methoquinone to a reactor equipped with a stirrer equipped with a reflux condenser, an air introduction pipe, and a thermometer. . After reacting at 90 ° C. for 9 hours, 539 parts of Plaxel G101 (produced by Daicel Chemical Industries, Ltd., ε-caprolactone adduct of bisphenol A type epoxy resin, epoxy equivalent 550 g / equivalent) and 1.6 parts of triphenylphosphine were added, and 100 ° C. for 8 hours. Reacted. 200 parts of phenoxyethyl acrylate was added and cooled to obtain <J-1> having an acid value of 0.6 KOH mg / g and a viscosity (40 ° C., mPas) 950. The GPC measurement molecular weight was a number average molecular weight (Mn) 1110, a weight average molecular weight (Mw) 2210, and a dispersity (Mw / Mn) was 1.99.

<Synthesis Example-2>
Into a reactor equipped with a stirrer equipped with a reflux condenser, a decanter for separating water and an air inlet, and a thermometer, Epicron 1055 (Dai Nippon Ink Chemical Co., Ltd. bisphenol A type epoxy resin, epoxy equivalent 478 g / equivalent) 865 parts, 133 parts of acrylic acid, 0.5 parts of methoquinone and 2 parts of triphenylphosphine were added and reacted at 95 ° C. for 5 hours to obtain <h-1> having an acid value of 1.0 KOH mg / g and a melting point of 49 ° C. The molecular weight measured by GPC was a number average molecular weight (Mn) 1439, a weight average molecular weight (Mw) 2892, and the dispersity (Mw / Mn) was 2.01.

<Synthesis Example-3>
346 parts YD-8125 (Toto Kasei Co., Ltd. bisphenol A type epoxy resin, epoxy equivalent 173 g / equivalent) in a reactor equipped with a reflux condenser, a decanter for separating water and an air introduction pipe, and a thermometer , And light ester HOA-MPL (half ester of phthalic anhydride and 2-acryloyloxyethyl phthalate, manufactured by Kyoeisha Chemical Co., Ltd.), 0.4 part of methoquinone, 2 parts of triphenylphosphine, and 98 ° C. for 5 hours The reaction yielded an acid value of 0.9 KOH mg / g and semi-solid <h-2>. The GPC measurement molecular weight was number average molecular weight (Mn) 1140, weight average molecular weight (Mw) 1769, and dispersity (Mw / Mn) was 1.55.

<Production of UV-curable composition and optical disc>
Each composition blended according to the composition shown in Table 1 and Table 2 below was heated and dissolved at 60 ° C. for 3 hours to prepare ultraviolet curable compositions of Examples and Comparative Examples. The viscosity of each composition was measured with a B-type viscometer at 25 ° C.

表１中、粘度の単位はｍＰａ・ｓ／２５℃

In Table 1, the unit of viscosity is mPa · s / 25 ° C.

The compounds in Table 1 are as follows.
EOTMPTA: Aronix M-350
(Trimethylolpropane triethoxytriacrylate manufactured by Toa Gosei)
BPE4-A: Light acrylate BP4EA (manufactured by Kyoeisha Chemical Co., Ltd.)
M220: Aronix M-220
(Tripropylene glycol diacrylate, manufactured by Toagosei Co., Ltd.)
Kayarad R-684: Nippon Kayaku Co., Ltd. Tricyclodecane dimethylol dimethacrylate TEGDA: Tetraethylene glycol diacrylate PHE: Osaka Organic Chemical Industry Co., Ltd. Phenoxyethyl acrylate THFA: Osaka Organic Chemical Industry Co., Ltd. Tetra Furfuryl acrylate PM-2: KAYAMA PM-2 Nippon Kayaku Co., Ltd. 2-methacryloylethyl acid phosphate Irg. 184: Irgacure 184 (Ciba Specialty Chemicals)
Irg. 651: Irgacure 651 (Ciba Specialty Chemicals)
TPO: Darocur TPO (Ciba Specialty Chemicals)
DBE: ethyl N-dimethylaminobenzoate

  The melting point of the oligomer h-1 is 49 ° C., and the viscosity at 25 ° C. cannot be measured, but the composition 3 containing only 15% of h-2 has a high viscosity and has reached the upper limit of the viscosity suitable for coating. . Composition 1 has an oligomer content of 25% and composition 2 has an oligomer content ratio of 43%, but the viscosity is lower than that of composition 3 in which the oligomer use ratio is 15%. The oligomer J1 can increase the oligomer content ratio of the ultraviolet curable composition for optical discs compared to the oligomer h-1 used in the composition 3.

(Production of DVD-9 disc)
One polycarbonate substrate for an optical disk in which an aluminum metal thin film (reflective layer) of 40 to 60 nm is laminated on irregularities called pits for recording information, and 15 nm silver on the irregularities called pits for recording information. One polycarbonate substrate for an optical disk on which a semi-transparent film (semi-transparent reflective layer) of an alloy as a component was laminated was prepared.
Next, each ultraviolet curable composition shown in Table 1 was applied onto the aluminum thin film of the substrate, and the substrate on which the semitransparent film of an alloy mainly composed of silver was further laminated was used. It overlapped with the substrate through an ultraviolet curable composition applied to the aluminum thin film surface so as to be an adhesive surface. Subsequently, it was rotated with a spin coater so that the film thickness of the cured coating film was about 50 to 60 μm. Next, using a “xenon flash irradiation device SBC-04 type” manufactured by Ushio Electric Co., Ltd., by irradiating 10 shot ultraviolet rays in air from the substrate side with the silver alloy translucent film at a set voltage of 1800 V, each ultraviolet curing type A DVD-9 type optical disk bonded with a cured film of the composition was produced.

(Measurement of adhesive strength before and after durability test)
On the surface of the metal reflective film of the polycarbonate substrate having an aluminum thin film or a semi-transparent film of an alloy mainly composed of silver as the metal reflective film, each ultraviolet curable composition shown in Table 1 is cured with a spin coater. The coating was applied to a thickness of about 50 to 60 μm, and the coating was cured with a metal halide UV lamp 120w, 0.5 J / cm ² manufactured by Eye Graphics Co., Ltd. to prepare a sample for measuring adhesive strength. About each sample, the durability test was done in 80 degreeC85% RH 24 hour high-temperature, high-humidity environment using "PR-2PK" by Espec Co., Ltd. After that, sandpaper # 1500 and # 280 are used to lightly polish the coating film so that the whole is thinly clouded. Then, the abrasive powder is wiped off with water and ethanol, and a 10 mm square jig is used with a structural adhesive WF-731 manufactured by Konishi Bond. Attached to the polished surface. The jig attached to the substrate was pulled with a push-pull gauge (500N full scale) manufactured by Tester Sangyo, and the tensile strength was measured to determine the adhesive strength.

(Measurement method of elastic modulus)
An ultraviolet curable composition was applied on a glass plate so that the cured coating film had a thickness of 50 to 60 μm, and then 500 mJ / cm ² in a nitrogen atmosphere using a metal halide lamp (with a cold mirror, lamp output 120 W / cm). And cured. The elastic modulus of this cured coating film was measured with an automatic dynamic viscoelasticity measuring apparatus manufactured by TA Instruments Inc., and the dynamic elastic modulus E ′ at 25 ° C. was defined as the elastic modulus.

  The elastic modulus (E ′ / MPa) of the cured coating film decreases when the oligomer of Synthesis Example J-1 is increased, but the oligomer h-1 of Synthesis Example 2 increases in elasticity when the oligomer content ratio is increased. Furthermore, when the elastic moduli (E '/ MPa) in Table 2 were compared, the elastic moduli of the cured films of the compositions 4 to 6 were higher than the elastic moduli of the cured films of the compositions 1 to 3. In particular, it can be seen that the compositions 5 and 6 containing the oligomer of h-2 have a high elastic modulus. From the above, when using a composition containing many oligomers with a special structure that does not increase the viscosity of the paint, it has excellent adhesive strength and is left in a high temperature and high humidity environment It can be seen that it is possible to obtain an optical disc having excellent durability and no adhesive discoloration.

Since the ultraviolet curable composition of the present invention uses many oligomers that do not increase the elastic modulus of the cured film, even if distortion occurs in the cured film, stress relaxation works, and the distortion is quickly removed. Therefore, even when exposed to a high temperature and high humidity environment, the initial adhesive strength does not decrease. In particular, in the optical disk using the ultraviolet curable composition of Example 2 using the composition containing 43% of oligomer J-1, the adhesive strength after the durability test is improved rather than the initial stage. This is a unique phenomenon found by the present invention, and proves that an optical disk using the ultraviolet curable composition of the present invention has excellent durability performance.

Claims (8)

A half ester compound (A) obtained from a hydroxyalkyl (meth) acrylate (a1) and a dibasic acid anhydride (a2);

(Wherein X represents —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) ₂ —, Y represents formula (2)

Wherein R ¹ is an alkylene group having 2 to 10 carbon atoms which may have a branched chain, and X is —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) _2- , n represents an integer of 1 to 10) and m groups represented by formula (3)

(Wherein X represents —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) ₂ —), and p groups represented by a random or block Represents a group connected in a shape. However, m is an integer of 1-10, p is an integer of 0-10. The ultraviolet curable composition for optical discs containing the epoxy acrylate resin obtained by making it react with the epoxy resin (B) represented by this. The ultraviolet curable composition for optical disks according to claim 1, wherein R ¹ in the formula (2) is-(CH ₂ ) _5- . Furthermore, Formula (4)

(Wherein R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently (i) a hydrogen atom, (ii) a halogen atom, (iii) a hydroxyl group, or (iv) a carbon number of 1-8). Alkoxyl group, (v) carboxyl group, (vi) formula (5)

(Wherein R ⁷ represents an alkyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom or an alkenyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom). Or (vii) a C1-C24 alkyl group or alkenyl group which may have a carboxyl group, an alkoxycarbonyl group, an acyloxyl group or an alkoxyl group as a substituent, R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are hydroxyl groups. The ultraviolet curable composition for optical discs of Claim 1 containing the compound represented by this. The compound represented by the formula (4) is represented by the formula (6),

(In the formula, R ⁸ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom, or an alkenyl group having 1 to 20 carbon atoms which may be substituted with a halogen atom.)
Equation (7),

(Wherein R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹³ , —OCOR ¹⁴ or An alkyl group having 1 to 24 carbon atoms which may have -OR ¹⁵ , or a 1 to 24 carbon atom which may have -COOH, -COOR ¹³ , -OCOR ¹⁴ or -OR ¹⁵ as a substituent. Represents an alkenyl group (wherein R ¹³ , R ¹⁴ and R ¹⁵ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms).
(Equation (8))

(Wherein R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹³ , —OCOR ¹⁴ or An alkyl group having 1 to 24 carbon atoms which may have -OR ¹⁵ , or a 1 to 24 carbon atom which may have -COOH, -COOR ¹³ , -OCOR ¹⁴ or -OR ¹⁵ as a substituent. Represents an alkenyl group (wherein R ¹³ , R ¹⁴ and R ¹⁵ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms).
Or formula (9)

(Wherein R ²⁰ , R ²¹ , R ²² and R ²³ are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹³ , —OCOR ¹⁴ or An alkyl group having 1 to 24 carbon atoms which may have -OR ¹⁵ , or a 1 to 24 carbon atom which may have -COOH, -COOR ¹³ , -OCOR ¹⁴ or -OR ¹⁵ as a substituent; Represents an alkenyl group (wherein R ¹³ , R ¹⁴ and R ¹⁵ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms). 4. The ultraviolet curable composition for optical disks according to claim 3, which is a compound. The compound represented by the formula (4) is gallic acid, catechol, 3-sec-butylcatechol, 3-tert-butylcatechol, 4-sec-butylcatechol, 4-tert-butylcatechol, 3,5-di- -Tert-butylcatechol, 3-sec-butyl-4-tert-butylcatechol, 3-tert-butyl-5-sec-butylcatechol, 4-octylcatechol, 4-stearylcatechol, hydroquinone, 2-hydroxyhydroquinone, 2 , 5-Di-tert-butylhydroquinone, 2,5-bis (1,1,3,3-tetramethylbutyl) hydroquinone, 2,5-bis (1,1-dimethylbutyl) hydroquinone, resorcinol, orcinol or pyrogallol The ultraviolet curable composition for optical disks according to claim 3. An optical disc comprising a first reflective film for reflecting information reading laser light on a first substrate, and further comprising a resin layer made of a cured film of an ultraviolet curable composition on the first reflective film. Because
An optical disc, wherein the ultraviolet curable composition is the ultraviolet curable composition according to any one of claims 1, 2, 3, 4 and 5. Furthermore, a second substrate provided with a second reflecting film for reflecting the laser beam for reading information is provided on the resin layer so that the resin layer and the second reflecting film are in contact with each other. The optical disk according to claim 6. 8. The optical disk according to claim 6, wherein the first reflective film is a reflective film made of gold or an alloy containing gold as a main component, silver or an alloy containing silver as a main component, or a silicon compound.