JP4385736B2 - Ultraviolet curable composition and optical disk using the same - Google Patents

Description

  The present invention relates to an ultraviolet curable composition for optical discs used for producing optical discs, and in particular, an ultraviolet curable composition for optical discs used when two substrates having at least one information recording layer are bonded together. The present invention relates to an object and an optical disk using the same.

  Currently, in the technical field of optical discs, there is an increasing market demand for DVDs (digital video discs or digital versatile discs) having a larger recording capacity than conventional compact discs (CDs). There are various variations in the process of manufacturing the DVD. Basically, the DVD is manufactured by a method of bonding two substrates, at least one of which has an information recording layer. The composition is used as an adhesive.

  The reproduction-only DVD is classified as DVD-5, DVD-10, DVD-9, or DVD-18 depending on the difference in the configuration of the two substrates to be bonded. Details of these configurations are disclosed in known documents (see, for example, Patent Document 1 and Patent Document 2), but the outline is as follows.

  As the two substrates to be bonded together, an unevenness called a pit corresponding to recording information is provided on one side of the substrate, and an aluminum layer, for example, is provided as a laser light reflecting film for reading information so as to cover the unevenness of the pit In this way, an information recording layer (also referred to as a reflection layer) is formed and used as a laser light reflection film, and these are opposed to each other (DVD-10), or one of the two sheets Uses a transparent substrate that does not have an information recording layer (DVD-5), or one substrate is provided with pit irregularities corresponding to the recorded information, and a half of gold or silicon compound or the like is provided so as to cover it. A transparent reflective layer (information recording layer) is formed, and the other substrate includes an aluminum reflective layer (information recording layer) (DVD-9). Furthermore, there is a DVD (DVD-18) having a structure in which two substrates each having two layers of a reflective layer and a semi-transparent reflective layer are bonded to each other, and is properly used depending on the application.

  By the way, although gold is mainly used for the translucent reflective layer on one substrate of DVD-9, since the price of the material is very high, the use of a silicon compound is currently being studied for the purpose of cost reduction. ing. Typical examples of silicon compounds used for such applications include silicon and silicon nitride. However, since a thin film of a silicon compound is different in malleability compared to a metal thin film such as gold, a substrate provided with a translucent reflective layer of a silicon compound is bonded with an ultraviolet curable composition and subjected to high temperature and high humidity conditions. When left for a long time, there is a problem that the translucent reflective layer is lifted from the transparent substrate by water and the disk surface becomes cloudy. For this reason, there has been a demand for an adhesive made of an ultraviolet curable composition capable of producing a bonded disc whose appearance does not become cloudy even after an environmental test.

Various techniques have been proposed for improving the adhesion to the metal or metal compound or silicon compound forming the information recording layer of the optical disc. For example, an example in which a silane coupling agent having an isocyanate group is used as a silane coupling agent is known (see, for example, Patent Document 3). Moreover, the example using the silane coupling agent which has an epoxy group, or the silane coupling agent which has a methacryloxy group is known (for example, refer patent document 4). However, these conventional techniques cannot sufficiently prevent alteration of the information recording layer made of a metal, a metal compound, or a silicon compound when left for a long time under a high temperature and high humidity condition. In particular, no technique has yet been found that can sufficiently solve the above-mentioned problems in a substrate provided with a translucent reflective layer of a silicon compound.
Japanese Patent Laid-Open No. 10-3699 JP 2001-266419 A JP 2003-157593 A JP 2001-311067 A

  The present invention has been made in view of the above circumstances. The object of the present invention is to provide an information recording layer made of a metal, a metal compound, or a silicon compound even when exposed to a high temperature and high humidity environment for a long time. An object of the present invention is to provide an ultraviolet curable composition for an optical disc that can sufficiently prevent deterioration. In particular, an object of the present invention is to provide an ultraviolet curable composition that prevents an information recording layer made of a silicon compound from floating on a transparent substrate and causing a disk to become clouded.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have applied an environmental test that is exposed to high temperature and high humidity conditions for a long time by using the following composition, and also applied pressure under high temperature and high humidity conditions. In super-accelerated tests called pressure cooker tests, we have found that discs with no change in appearance can be produced.

  That is, the present invention is an ultraviolet curable composition for optical discs containing a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent, wherein the photopolymerizable compound has the formula (I)

（式中、ＸはCH₂=CHCOO-、Ｙは-CH₂CH₂O-又は-CH₂CH₂CH₂CH₂O-、Ｚは-COCH=CH₂を表し、nは２〜１０の整数を表す。）で表される化合物、式(II)

(Wherein X represents CH ₂ ═CHCOO—, Y represents —CH ₂ CH ₂ O— or —CH ₂ CH ₂ CH ₂ CH ₂ O—, Z represents —COCH═CH ₂ , and n represents 2-10. A compound represented by the formula (II):

（式中、ＸはCH₂=CHCOO-を表す。）で表される化合物、式(III)

(Wherein X represents CH ₂ = CHCOO-), a compound represented by formula (III)

（式中、Ｒはそれぞれ独立的に、HO-又はCH₂=CHCOO-を表し、少なくとも２つのＲはCH₂=CHCOO-である。）で表される化合物、及び式(IV)

Wherein each R independently represents HO— or CH ₂ ═CHCOO—, and at least two R are CH ₂ ═CHCOO—, and a compound of formula (IV)

（式中、Ｒはそれぞれ独立的に、HO-又はCH₂=CHCOO-を表し、少なくとも２つのＲはCH₂=CHCOO-である。）で表される化合物から選択される１又は２種以上の化合物を含有し、前記シランカップリング剤が分子中にイソシアネート基を有するシランカップリング剤であることを特徴と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 R independently represents HO— or CH ₂ ═CHCOO—, and at least two R are CH ₂ ═CHCOO—). And a silane coupling agent having an isocyanate group in the molecule. The ultraviolet curable composition for optical discs is provided.

  Further, the present invention provides two optical disk substrates having a reflective layer made of a metal thin film on the surface, or an optical disk substrate having a reflective layer made of a metal thin film on the surface and an optical disk substrate not having the reflective layer, An optical disk in which a reflective layer is used as an adhesive surface and bonded together with an adhesive, wherein the adhesive is the above-described ultraviolet curable composition for optical disks.

  The present invention also provides two optical discs in which a translucent reflective layer made of a silicon compound, a cured film layer made of the above-mentioned ultraviolet curable composition for optical discs, and a reflective layer made of a metal thin film are laminated in this order on a substrate. A laminated optical disk in which the substrate is bonded with an adhesive with the reflective layers as the bonding surfaces is provided.

  The compounds of the above formulas (I) to (IV) are bifunctional or higher acrylates and have an action of increasing the crosslinking density. Generally, a cured film having a high crosslinking density tends to exhibit hydrophobicity. However, since the alcohol component of these compounds is rich in hydrophilicity, the ultraviolet curable composition of the present invention containing these compounds can provide a cured film having a balance between hydrophilicity and hydrophobicity, particularly at high temperatures and high temperatures. It is suitable as a material for protecting a thin film of a silicon compound that easily generates water droplets at the interface between the reflective film and the cured film in a wet environment and bonding it to another substrate.

  The ultraviolet curable composition of the present invention containing a silane coupling agent having an isocyanate group not only improves the adhesive force, but also has excellent durability in a high temperature and high humidity environment. A material that protects the thin film of silicon compound that is susceptible to water droplets at the interface between the reflective film and the cured film in the above environment and adheres it to other substrates because of the good balance between aqueous and isocyanate group hydrophilicity. It is suitable as.

  Therefore, by using the ultraviolet curable composition of the present invention, for example, DVD-9 having a translucent reflective layer made of a silicon compound on one disk substrate, or a translucent reflective layer made of a silicon compound on both disk substrates. An optical disc such as DVD-18 having a favorable characteristic with excellent durability and reliability can be obtained.

  As described above, the compound represented by the formula (I), the compound represented by the formula (II), the compound represented by the formula (III), and the formula contained in the ultraviolet curable composition for optical discs of the present invention. A combination of one or more compounds selected from compounds represented by (IV) and a silane coupling agent having an isocyanate group in the molecule is a reflective layer comprising a metal thin film formed on an optical disk substrate Alternatively, it is a component constituting an adhesive for applying to the surface of a translucent reflective layer made of a silicon compound and bonding to another optical disk substrate, and the reflective layer or the translucent reflective layer is deteriorated by moisture. It functions as a deterioration preventing agent for preventing this.

  The ultraviolet curable composition of the present invention contains a specific compound and a silane coupling agent, thereby exhibiting sufficient adhesive force between the metal or the metal compound forming the information recording layer, such as high temperature and high humidity. To form a cured film with excellent durability that can prevent the information recording layer from degrading or peeling off the information recording layer and the cured film of the UV curable composition even when exposed to the environment for a long time. Can do. In particular, a conventional ultraviolet curable composition can form a cured film having sufficient durability without clouding even when a semi-transparent reflective layer of a silicon compound that causes the disk surface to become cloudy after an environmental test is used. Can do.

  The present invention will be described in detail below. In the present specification, (meth) acrylic acid means acrylic acid or methacrylic acid, and (meth) acrylate means acrylate or methacrylate.

  In the ultraviolet curable composition of the present invention, one or more compounds selected from the compounds of the above formulas (I) to (IV) are used, and among these, the compounds represented by the following formula (V) are used. It is preferable that it is 1 type, or 2 or more types of compounds chosen from the compound represented by said compound, the compound represented by said Formula (II), and the compound represented by following formula (VI). Among these, a compound represented by the following formula (V) is more preferable. Furthermore, among the compounds represented by the following formula (V), n is particularly preferably 2 to 6.

（式中、nは２〜１０の整数を表す。）

(In the formula, n represents an integer of 2 to 10.)

  The compound represented by the formula (V) is polyethylene glycol diacrylate, the compound represented by the formula (II) is neopentyl glycol diacrylate hydroxypivalate, and the compound represented by the formula (VI). Is pentaerythritol triacrylate.

  In the ultraviolet curable composition of the present invention, 1 to 30 compounds selected from the compounds of the above formulas (I) to (IV) are used in an amount of 1 to 30 with respect to 100 parts by mass of the ultraviolet curable composition. Use of parts by mass is preferable from the viewpoint of adhesion to the reflective layer. Moreover, it is more preferable that it is 5-25 mass parts in 100 mass parts of ultraviolet curable compositions, and it is especially preferable that it is 5-20 mass parts.

  In the present invention, compounds other than the above formulas (I) to (IV) can be used as the photopolymerizable compound in order to adjust the viscosity and other properties. Other photopolymerizable compounds include relatively low molecular weight polymerizable monomers (A) such as the following monofunctional (meth) acrylates and polyfunctional (meth) acrylates, and higher molecular weight polymerizable oligomers (B) These can be used alone or in combination.

  Examples of the polymerizable monomer (A) that can be used in the present invention include the following. Examples of monofunctional (meth) acrylates include ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, hexadecyl (meth) acrylate, and octadecyl. (Meth) acrylate, isoamyl (meth) acrylate, isodecyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, Nonylphenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate 2-hydroxy-3-phenoxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, nonylphenoxyethyl tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) ) Acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and the like.

  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, tri Cyclodecanedimethanol di (meth) acrylate, ethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, etc., di (meth) acrylate of tris (2-hydroxyethyl) isocyanurate, 4 per mole of neopentyl glycol More than moles of ethylene oxide Di (meth) acrylate of diol obtained by adding propylene oxide, 2 mol of ethylene oxide or diol obtained by adding propylene oxide to 1 mol of bisphenol A, 3 mol of 1 mol of trimethylolpropane Diol or tri (meth) acrylate of triol obtained by adding the above ethylene oxide or propylene oxide, di (meth) acrylate of diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of bisphenol A, Trimethylolpropane tri (meth) acrylate, pentaerythritol trimethacrylate, polymethacrylate of dipentaerythritol, ethylene oxide modified phosphoric acid (meth) acrylate, ethylene oxy Id modified alkylated phosphoric acid (meth) acrylate.

  Furthermore, examples of the radical polymerizable oligomer include polyester (meth) acrylate, polyether (meth) acrylate, epoxy (meth) acrylate, and urethane (meth) acrylate.

  The polyfunctional (meth) acrylate was obtained by adding 3 mol or more of ethylene oxide to 1 mol of trimethylolpropane, and adding 4 mol or more of ethylene oxide to 1 mol of bisphenol A. It is preferable to use diacrylate, pentaerythritol trimethacrylate, ethylene oxide-modified phosphoric acid (meth) acrylate, ethylene oxide-modified alkylated phosphoric acid (meth) acrylate, or the like.

  Furthermore, there exist polyester (meth) acrylate, polyether (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate etc. as a polymerizable oligomer (B). In the present invention, it is preferable to use a urethane acrylate oligomer.

  The silane coupling agent having an isocyanate group used in the present invention is chemically bonded to an organic material in addition to an alkoxysilyl group, a silanol group, etc. that are hydrogen bonded to an inorganic substance such as glass or metal directly or through a hydrolysis reaction. A silane coupling agent having an isocyanate group.

  Examples of the compound having a silyl group include an alkoxysilane compound and a halogenated silane compound. In the present invention, an alkoxysilane compound is preferable. An alkoxysilane compound refers to a compound containing one or more alkoxysilyl groups. Examples of the alkoxysilyl group include a trimethoxysilyl group, a triethoxysilyl group, a methyldimethoxysilyl group, a methyldiethoxysilyl group, and a tris (βmethoxyethoxy) silyl group. Among these, a trimethoxysilyl group and a triethoxy group are available. It preferably has a silyl group. The ultraviolet curable composition containing an alkoxysilane compound having a trimethoxysilyl group or a triethoxysilyl group has excellent standing stability.

  Examples of the silane coupling agent having an isocyanate group suitable for the present invention include γ-isocyanatopropyltriethoxysilane, γ-isocyanatepropyltrimethoxysilane, and γ-isocyanatopropylmethyldimethoxysilane. Among these, γ-isocyanatopropyltriethoxysilane is particularly preferable.

  Such a silane coupling agent is commercially available, for example, as trade name KBE9007 (γ-isocyanatopropyltriethoxysilane) manufactured by Shin-Etsu Silicone.

  In the ultraviolet curable composition of the present invention, the above silane coupling agent having an isocyanate group is used alone or in combination with other silane coupling agents. The amount of these silane coupling agents used is preferably 0.1 to 5 parts by mass in 100 parts by mass of the ultraviolet curable composition from the viewpoint of adhesiveness to the reflective layer. Moreover, it is more preferable that it is 0.3-4 mass parts in 100 mass parts of ultraviolet curable compositions, and it is especially preferable that it is 0.5-3 mass parts.

  Furthermore, various known silane coupling agents can be used in combination as long as the effects of the ultraviolet curable composition of the present invention are not impaired. Examples of such compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane. Γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-acryloxy B pills methyl diethoxy silane, .gamma. acryloxy propyl triethoxy silane, .gamma.-mercaptopropyltrimethoxysilane, .gamma.-mercaptopropyl triethoxysilane, there is .gamma.-mercaptopropyl methyl dimethoxy silane.

  In this invention, a photoinitiator can be used as needed. As the photopolymerization initiator, known and conventional ones can be used, but those of molecular cleavage type or hydrogen abstraction type are suitable for the present invention.

  Examples of the photopolymerization initiator that can be used in the present invention include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, benzyl, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethyl. Amino-1- (4-morpholinophenyl) -butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, etc. are preferably used, and other than these As the molecular cleavage type, 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2- Hydroxy-2-methylpropa -1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one may be used in combination, and benzophenone, which is a hydrogen abstraction type photopolymerization initiator, 4 -Phenylbenzophenone, isophthalphenone, 4-benzoyl-4'-methyl-diphenyl sulfide and the like can be used in combination.

  It is preferable that the usage-amount of a photoinitiator is 0.1-20 mass parts with respect to 100 mass parts of ultraviolet curable compositions. Moreover, it is more preferable that it is 0.5-15 mass parts in 100 mass parts of ultraviolet curable compositions, and it is especially preferable that it is 1-10 mass parts.

  Moreover, a sensitizer can also be used with the said photoinitiator. Examples of the sensitizer include trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzylamine, and 4, An amine that does not cause an addition reaction can be used in combination with the above polymerizable component, such as 4′-bis (diethylamino) benzophenone. Of course, it is preferable to select and use the photopolymerization initiator and the sensitizer that are excellent in solubility in the ultraviolet curable compound and do not inhibit the ultraviolet transmittance.

  It is preferable that the usage-amount of a sensitizer is 0.1-20 mass parts with respect to 100 mass parts of ultraviolet curable compositions. Moreover, it is more preferable that it is 0.5-15 mass parts in 100 mass parts of ultraviolet curable compositions, and it is especially preferable that it is 1-10 mass parts.

  The ultraviolet curable composition of the present invention is preferably liquid at room temperature to 40 ° C. Further, it is preferable not to use a solvent, and even if it is used, it is better to keep it as small as possible. In addition, examples of the method for applying the ultraviolet curable composition of the present invention to a disk include a roll coater method and a spin coat method, but it is preferable to use a spin coat method. When the ultraviolet curable composition of the present invention is applied to a disk by a spin coater method, the viscosity is preferably adjusted to 10 to 3000 mPa · s, and preferably 20 to 2000 mPa · s. In particular, in the case of a bonded optical disc such as a DVD, when the thickness of the adhesive layer is 40 μm or more, it is preferably prepared to be 30 to 1500 mPa · s.

  Further, in the ultraviolet curable composition of the present invention, if necessary, as other additives, thermal polymerization inhibitors, hindered phenols, hindered amines, antioxidants typified by phosphites, plasticizers, etc. Can also be blended for the purpose of improving various properties. These are selected from those having excellent solubility in ultraviolet curable compounds and those that do not impair ultraviolet transparency.

  The ultraviolet curable composition of the present invention can be obtained by uniformly mixing the above-described components by an ordinary method.

  The ultraviolet curable composition of the present invention is advantageously used as an adhesive for bonded optical disks. The substrate of the disk is preferably a substrate of polycarbonate, polymethyl methacrylate, amorphous polyolefin or the like.

A bonded optical disk such as DVD-9 using the ultraviolet curable composition of the present invention is produced by the following method. First, uneven pits (P ₁ ) are formed on the substrate (1) as recorded information. Then, a reflective layer is laminated consisting of an aluminum thin film of 40~60nm over the pit _{(P 1),} to form the information recording layer _{(M 1).} Separately, a substrate (2) is prepared, and uneven pits (P ₂ ) are formed on the substrate (2) as recording information. The pits _{(P 2)} laminating a translucent reflective layer of a silicon compound of 10~30nm on, to form the information recording layer _{(M 2).} As the translucent film, gold has been mainly used so far. However, since gold is expensive, it is preferable to use a silicon compound such as silicon nitride or silicon instead.

Next, the ultraviolet curable composition of the present invention is uniformly coated on the information recording layer (M ₁ ) of the substrate (1), and the information recording layer (P ₂ ) of the substrate ( ₂ ) is in contact with the coated surface. In the state, it is bonded so as to face the information recording layer (1). Thereafter, ultraviolet light is applied from one or both sides of the bonded substrate (1) and substrate (2) to bond them together to manufacture DVD-9. The ultraviolet curable composition of the present invention after irradiation with ultraviolet rays becomes a cured film and forms an adhesive layer that bonds the substrate (1) and the substrate (2). In order to prevent the optical disk from being deformed by heat, it is preferable to irradiate with flash light when irradiating ultraviolet rays.

  By doing so, a substrate having a reflective layer made of a metal thin film on one side and a substrate having a translucent reflective layer made of a silicon compound on the other side, the reflective layer and the transparent reflective layer as an adhesive surface. An optical disk bonded with the ultraviolet curable composition of the invention can be produced.

At present, the thickness of the adhesive layer in DVD-9 is 40 to 70 μm according to the standard, and the ultraviolet curable composition of the present invention is applied to the information recording layer (M ₁ ) of the substrate (1). Sometimes, it is uniformly applied so that the thickness of the adhesive layer when the ultraviolet curable composition is cured is in the above range.

Further, without forming pits on the substrate (2), that is, without providing the information recording layer _{(M 2),} when bonded to a substrate (1) is a DVD-5.

  By doing so, it is possible to manufacture an optical disc in which a substrate provided with a reflective layer made of a metal thin film on one side is bonded to another substrate with the ultraviolet curable composition of the present invention using the reflective layer as an adhesive surface.

Further, by forming a substrate (2) uneven pits on _{(P 2),} the information recording layer by laminating a reflective layer of aluminum thin 40~60nm over the pit _{(P 2) (M 2} ) And the information recording layer (M ₁ ) of the substrate ( ₁ ) and the information recording layer (M ₂ ) of the substrate ( ₂ ) are bonded to each other by the ultraviolet curable composition of the present invention. After bonding, ultraviolet rays are irradiated from one side or both sides of the bonded substrates (1) and (2) to obtain DVD-10.

  By doing so, it is possible to manufacture an optical disc in which two substrates provided with a reflective layer made of a metal thin film are bonded together with the ultraviolet curable composition of the present invention using the reflective layers as an adhesive surface.

Furthermore, after manufacturing the DVD-9, only the substrate (1) is peeled off while leaving the reflective layer formed on the substrate (1) on the substrate (2) side. A disc intermediate in which the information recording layer (M ₂ ) / cured film of the ultraviolet curable composition of the present invention / information recording layer (M ₁ ) are sequentially laminated is prepared. Two such disk intermediates are prepared. Next, when the information recording layer (M ₁ ) of the two disc intermediates is used as an adhesive surface, the two disc intermediates are bonded so as to oppose each other. 18 is obtained. At this time, the ultraviolet curable composition of the present invention is preferably used as a material for bonding the disk intermediates together. By doing so, the adhesion between the information recording layers (M ₁ ) becomes stronger.

  By such a method, two substrates in which a translucent reflective layer made of a silicon compound, a cured layer of the ultraviolet curable composition of the present invention, and a reflective layer made of a metal thin film are laminated in this order on the substrate. Thus, an optical disk in which the reflective layers are bonded to each other as an adhesive surface can be manufactured. Moreover, an optical disk in which the reflective layers of the substrate are bonded together by the ultraviolet curable composition of the present invention can be produced.

  The substrate of the disk is preferably a substrate of polycarbonate, polymethyl methacrylate, amorphous polyolefin or the like.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples. Hereinafter, “parts” in the examples represent “parts by mass”.

Example 1
As an ultraviolet curable compound, 33 parts of urethane acrylate (urethane A) obtained by reacting 1 mol of polytetramethylene glycol (number average molecular weight 850) with 2 mol of tolylene diisocyanate and then 2 mol of hydroxyethyl acrylate, polyethylene glycol diacrylate 13 Parts (number average molecular weight 200), ethylene oxide modified bis A type diacrylate 10 parts (BPE4-A: number average molecular weight 512), 2-hydroxy-3-phenoxypropyl acrylate 23 parts, tetrahydrofurfuryl acrylate 12 parts, ethylene oxide 1.5 parts of modified trimethylolpropane triacrylate (EOTMPTA: number average molecular weight 600), 0.2 part of ethylene oxide-modified phosphate methacrylate (trade name PM-2, manufactured by Nippon Kayaku Co., Ltd.), dimethyl alcohol 0.3 parts of ethyl benzoate, 1 part of 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 6 parts of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator, and γ-isocyanatopropyltriethoxysilane as a silane coupling agent One part was heated and mixed and dissolved at 60 ° C. for 1 hour to prepare a light yellow transparent ultraviolet curable composition.

(Example 2)
33 parts of urethane acrylate (urethane A) obtained by reacting 1 mol of polytetramethylene glycol (number average molecular weight 850) and 2 mol of tolylene diisocyanate as a UV curable compound and 2 mol of hydroxyethyl acrylate, neopentyl hydroxypivalate 5 parts of glycol diacrylate, 13 parts of polyethylene glycol diacrylate (number average molecular weight 200), 10 parts of ethylene oxide modified bis A type diacrylate (BPE4-A: number average molecular weight 512), 2-hydroxy-3-phenoxypropyl acrylate 18 Parts, tetrahydrofurfuryl acrylate 12 parts, ethylene oxide modified trimethylolpropane triacrylate (EOTMPTA: number average molecular weight 600) 1.5 parts, ethylene oxide modified phosphate meta 0.2 parts of Relate (trade name PM-2 manufactured by Nippon Kayaku Co., Ltd.), 0.3 parts of ethyl dimethylaminobenzoate, 1 part of 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator, and 6 parts of 1-hydroxycyclohexyl phenyl ketone and 1 part of γ-isocyanatopropyltriethoxysilane as a silane coupling agent were heated, mixed and dissolved at 60 ° C. for 1 hour to prepare a light yellow transparent ultraviolet curable composition.

(Example 3)
As an ultraviolet curable compound, 33 parts of urethane acrylate (urethane A) obtained by reacting 1 mole of polytetramethylene glycol (number average molecular weight 850) with 2 moles of tolylene diisocyanate and 2 moles of hydroxyethyl acrylate, pentaerythritol triacrylate 5 Parts, polyethylene glycol diacrylate 13 parts (number average molecular weight 200), ethylene oxide-modified bis A type diacrylate 10 parts (BPE4-A: number average molecular weight 512), 2-hydroxy-3-phenoxypropyl acrylate 18 parts, tetrahydrofur 12 parts of furyl acrylate, 1.5 parts of ethylene oxide modified trimethylolpropane triacrylate (EOTMPTA: number average molecular weight 600), ethylene oxide modified phosphate methacrylate (Nippon Kayaku Product name PM-2) 0.2 parts, ethyl dimethylaminobenzoate 0.3 parts, 1,4,6-trimethylbenzoyldiphenylphosphine oxide 1 part and 1-hydroxycyclohexyl phenyl ketone as photopolymerization initiator 6 parts, 1 part of γ-isocyanatopropyltriethoxysilane as a silane coupling agent was heated and mixed and dissolved at 60 ° C. for 1 hour to prepare a light yellow transparent UV curable composition.

  Furthermore, the ultraviolet curable composition of Example 4 and Example 5 was prepared by the mixing | blending of Table 1. FIG.

(Comparative Example 1)
A pale yellow transparent UV curable composition was prepared in the same manner as in Example 1 except that no silane coupling agent was added.

(Comparative Example 2)
In Example 1, a light yellow transparent UV curable composition was prepared in the same manner as in Example 1 except that tripropylene glycol diacrylate was used instead of 13 parts of polyethylene glycol diacrylate as the (meth) acrylate compound. .

(Comparative Example 3)
15 parts of Unidic V-5500 (Dainippon Ink Chemical Co., Ltd.) as a bisphenol A type epoxy acrylate as an ultraviolet curable compound, 1 mol of polytetramethylene glycol (number average molecular weight 1000) and 2 mol of isophorone diisocyanate after reaction 14 parts of urethane acrylate (urethane B) obtained by reacting 2 mol of ethyl acrylate, 22 parts of tripropylene glycol diacrylate, 22 parts of 2-hydroxy-3-phenoxypropyl acrylate, 18 parts of ethyl carbitol acrylate, ethylene oxide modified tri 1.5 parts of methylolpropane triacrylate (EOTMPTA: number average molecular weight 600), 0.2 part of ethylene oxide-modified phosphate methacrylate (trade name PM-2, manufactured by Nippon Kayaku Co., Ltd.), dimethyl alcohol 0.3 parts of ethyl benzoate, 2 parts of 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 4 parts of 1-hydroxycyclohexyl phenyl ketone as photopolymerization initiator, and γ-isocyanatopropyltriethoxysilane as silane coupling agent One part was heated and mixed and dissolved at 60 ° C. for 1 hour to prepare a light yellow transparent ultraviolet curable composition.

(Comparative Example 4)
In Comparative Example 3, a light yellow transparent UV curable type was used in the same manner as in Example except that γ-acryloxypropylmethyldiethoxysilane was used instead of 1 part of γ-isocyanatopropyltriethoxysilane as a silane coupling agent. A composition was prepared.

  DVD-9 bonded discs were manufactured using the ultraviolet curable compositions obtained in the above Examples and Comparative Examples, and durability was evaluated by the following test methods. The results are shown in Tables 1 and 2. Abbreviations in the table are as follows.

Urethane A: Urethane acrylate Urethane B: Urethane acrylate V-5500: Bis A type epoxy acrylate (manufactured by Dainippon Ink & Chemicals, Inc.)
PETA: pentaerythritol triacrylate MANDA: hydroxypivalate neopentyl glycol diacrylate (manufactured by Nippon Kayaku Co., Ltd.)
TPGDA: Tripropylene glycol diacrylate PEGDA: Polyethylene glycol diacrylate BPE4-A: Ethylene oxide modified bis A type diacrylate (number average molecular weight 512)
M-5700: 2-hydroxy-3-phenoxypropyl acrylate (manufactured by Toagosei Co., Ltd.)
THFA: Tetrahydrofurfuryl acrylate CBA: Carbitol acrylate PM-2: Ethylene oxide modified phosphate methacrylate (trade name PM-2, manufactured by Nippon Kayaku Co., Ltd.)
EOTMPTA: ethylene oxide-modified trimethylolpropane triacrylate (number average molecular weight 600)
DBE: ethyl dimethylaminobenzoate Irg-184: 1-hydroxycyclohexyl phenyl ketone TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide isocyanate Si: γ-isocyanatopropyltriethoxysilane acrylic Si: γ-acryloxypropylmethyl Diethoxysilane

<Test method: Durability of DVD-9 bonded disc>
Prepared is a polycarbonate disk substrate on which a pit for recording information is formed and an aluminum thin film having a thickness of 50 nm is laminated so as to cover the pit, and the ultraviolet curable composition of each example and comparative example is formed on the aluminum thin film surface. Was applied with a dispenser, and a polycarbonate disk substrate on which a silicon compound was laminated as a translucent reflective film was overlaid so that the translucent reflective film was in contact with the ultraviolet curable composition. Subsequently, it was rotated at 1500 rotations for 6.0 seconds so that the film thickness of a cured coating film might be set to about 50-60 micrometers with a spin coater. Next, using a “xenon flash irradiation device SBC-04 type” manufactured by Ushio Electric Co., Ltd., a DVD-9 was produced by irradiating with 10 shot ultraviolet rays in the air from the substrate side with a silicon compound translucent film at a set voltage of 1800V.

  Pressure cooker test using the bonded disc produced by the above method and leaving it in an environment of 105 ° C. and 100% RH 1 to 2 atm in an advanced accelerated life test apparatus “TPC-221” manufactured by Tabay Espec Co., Ltd. PCT test), a test (endurance test) was conducted for 96 hours in an environment of 80 ° C. and 85% RH using “Etac SD01” manufactured by Enomoto Kasei Co., Ltd.

The appearance of the surface of the disk after the acceleration test was observed with an Olympus differential interference microscope BX60.

  Evaluation of signal characteristics (measurement of error rate) before and after the environmental test was performed using “DQL-300D” manufactured by Sony Precision Technology, and the rate of increase in PI (Parity of Inner) error rate before and after the test (after the environmental test) Value / value before environmental test). The maximum error rate was the measured value. A smaller increase rate of the error rate means that the error rate is not affected when stored in a high temperature and high humidity environment. Conversely, the greater the rate of increase, the worse the storage durability under high temperature and high humidity.

  As a result of testing a DVD-9 type bonded disk using a translucent film of a silicon compound, it was found that any of polyethylene glycol diacrylate, neopentyl glycol diacrylate hydroxypivalate, and pentaerythritol triacrylate was used as an essential component. The optical disk bonded with the ultraviolet curable composition to which the silane coupling agent having a group was added was excellent in the disk surface without being clouded even after the durability test and the PCT test, and the change in the signal characteristics was very small. . On the other hand, as shown in the comparative example, an ultraviolet curable composition composed only of (meth) acrylate compounds other than polyethylene glycol diacrylate, hydroxypivalate neopentyl glycol diacrylate, and pentaerythritol triacrylate, and having an isocyanate group In an optical disk bonded with an ultraviolet curable composition using a silane coupling agent other than a silane coupling agent, the disk surface becomes cloudy even when the signal characteristics are good, and the ultraviolet curable composition of the example It was inferior compared with the optical disk bonded together.

In addition, a DVD-9 type optical disk was prepared in the same manner as in the above test example except that a gold thin film was used in place of the silicon compound as the translucent film. When the above composition was used, the signal characteristics of the disk changed very little even after the durability test and the PCT test. On the other hand, when the composition of the comparative example was used, the metal thin film used for the information recording layer was corroded, and the change in the signal characteristics of the disc was very large.

Claims (7)

An ultraviolet curable composition for an optical disk comprising a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent, wherein the photopolymerizable compound has the formula (I)

(Wherein X represents CH ₂ ═CHCOO—, Y represents —CH ₂ CH ₂ O— or —CH ₂ CH ₂ CH ₂ CH ₂ O—, Z represents —COCH═CH ₂ , and n represents 2-10. A compound represented by the formula (II):

(Wherein X represents CH ₂ = CHCOO-), a compound represented by formula (III)

Wherein each R independently represents HO— or CH ₂ ═CHCOO—, and at least two R are CH ₂ ═CHCOO—, and a compound of formula (IV)

(Wherein R independently represents HO— or CH ₂ ═CHCOO—, and at least two R are CH ₂ ═CHCOO—). And a silane coupling agent having an isocyanate group in the molecule, the ultraviolet curable composition for optical discs. The content of one or more compounds selected from the compounds represented by the formula (I), the formula (II), the formula (III), and the formula (IV) is the ultraviolet curable composition. The ultraviolet curable composition for optical discs according to claim 1, wherein the amount is 1 to 30 parts by mass per 100 parts by mass of the product. 3. The ultraviolet curable composition for an optical disk according to claim 1, wherein the compound represented by the formula (I) is a compound represented by the following formula (V).

(In the formula, n represents an integer of 2 to 10.) The ultraviolet curable composition for optical disks according to any one of claims 1 to 3, wherein the compound represented by the formula (III) is a compound represented by the following formula (VI).

5. The optical disk according to claim 1, wherein the silane coupling agent is at least one selected from γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, or γ-isocyanatopropylmethyldimethoxysilane. UV curable composition. Applied to the surface of a reflective layer made of a metal thin film or a translucent reflective layer made of a silicon compound formed on an optical disk substrate and used as one component of an adhesive for bonding to another optical disk substrate, A deterioration preventing agent for preventing the reflective layer or the translucent reflective layer from being deteriorated by moisture,
Formula (I)

(Wherein X represents CH ₂ ═CHCOO—, Y represents —CH ₂ CH ₂ O— or —CH ₂ CH ₂ CH ₂ CH ₂ O—, Z represents —COCH═CH ₂ , and n represents 2-10. A compound represented by the formula (II):

(Wherein X represents CH ₂ = CHCOO-), a compound represented by formula (III)

Wherein each R independently represents HO— or CH ₂ ═CHCOO—, and at least two R are CH ₂ ═CHCOO—, and a compound of formula (IV)

(Wherein R independently represents HO— or CH ₂ ═CHCOO—, and at least two R are CH ₂ ═CHCOO—). And an anti-deterioration agent for the reflective layer or translucent reflective layer of a bonded optical disk, comprising as an active ingredient a compound of the above and a silane coupling agent having an isocyanate group in the molecule. Two optical disk substrates having a reflective layer made of a silicon compound on the surface, or an optical disk substrate having a reflective layer made of a silicon compound on the surface and an optical disk substrate not having the reflective layer , with the reflective layer as an adhesive surface An optical disk bonded with an adhesive, wherein the adhesive is the ultraviolet curable composition for an optical disk according to claim 1 or 2.