JP2009032303A - Ultra violet ray curing composition for optical disk, and optical disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a UV curing composition providing an optical disk nearly free from deterioration of signal characteristics even when being exposed under high temperature and high humidity environment for a long term. <P>SOLUTION: The optical disk wherein corrosion and discoloration of a reflection film under high temperature and high humidity environment can be suppressed and reflectance change is less can be formed by using the UV curing composition containing a compound having a phenolic hydroxyl group, such as a gallic acid and a specified compound having two phenolic hydroxyl groups in one molecule and alkyl groups adjacent to the hydroxyl groups. Thereby, the optical disk nearly free from characteristics deterioration even under high temperature and high humidity environment can be provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultraviolet curable composition useful as a cured coating laminated on a light reflecting layer of an optical disc, and an optical disc having a layer made of the cured coating of the ultraviolet curable composition on the light reflecting layer.

  In recent years, silver, which has a high light reflectivity and is inexpensive, has become the mainstream as a material for a light reflecting layer used in an optical disk such as a CD, a DVD, or a Blu-Ray Disk. However, since silver has low corrosion resistance, in order to ensure the durability and reliability of an optical disk that uses silver as a light reflecting layer, an ultraviolet ray that forms a light transmitting layer or an adhesive layer directly laminated with the light reflecting layer is used. Selection of a curable composition is important. In particular, in a recordable optical disc such as a CD-R or DVD-R, if a signal cannot be recorded satisfactorily, errors at the time of reproduction increase. Therefore, higher durability is required compared to a read-only optical disc.

  Such a recordable optical disc is required to have durability in a poor environment so that a recorded signal can be stably reproduced over a long period of time. Examples of the ultraviolet curable composition that gives an optical disk excellent in durability when exposed to a high temperature and high humidity environment include, for example, a lactone-modified epoxy acrylate and a specific compound having a phenolic hydroxyl group such as gallic acid. Has been disclosed (see Patent Document 1). The composition can form an optical disc with little discoloration of the reflective film and increase in PI error (parity of inner-code error) even when exposed to a high temperature and high humidity environment. The composition has little signal characteristic deterioration and excellent durability even in an exposure test under a high temperature and high humidity environment. However, in a recordable optical disc, information once recorded should not deteriorate as long as possible. Therefore, further long-term durability has been required.

  Moreover, a composition containing urethane (meth) acrylate is disclosed as a composition used for coating for protecting an optical disk recording layer (see Patent Document 2). In the composition, it is disclosed that various antioxidants may be contained, but even if a composition containing an antioxidant is simply applied, the durability has not yet been extended. .

JP 2006-164390 A JP 2002-230831 A

  The problem to be solved by the present invention is to provide an ultraviolet curable composition that provides an optical disc with little deterioration in signal characteristics even when exposed to a high temperature and high humidity environment for a long period of time.

  In the present invention, a compound having a phenolic hydroxyl group such as gallic acid and a specific compound having two phenolic hydroxyl groups in the same molecule and having an alkyl group adjacent to the hydroxyl group are used in combination. A specific compound having two phenolic hydroxyl groups in the same molecule and having an alkyl group adjacent to the hydroxyl group is more easily oxidized than a phenolic hydroxyl group-containing compound having an inhibitory effect on increase in PI error. By delaying the oxidation of the compound and maintaining the function of the oxidizable phenolic hydroxyl group-containing compound such as gallic acid, it is possible to suitably prevent the deterioration of the reflective film even in a high temperature and high humidity environment.

  The ultraviolet curable composition of the present invention can suppress corrosion and discoloration of the reflective film in a high-temperature and high-humidity environment, and can form an optical disc with little change in reflectance. Fewer optical disks can be realized. An optical disc in which a cured film of such a composition is laminated with a light reflecting layer is less susceptible to deterioration of characteristics even in a high temperature and high humidity environment, so that signal characteristics are hardly deteriorated and information can be recorded / reproduced suitably. is there.

  The ultraviolet curable composition for optical discs of the present invention comprises an ultraviolet curable compound and a formula (1)

［式中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４及びＲ^５は各々独立して、水素原子、ハロゲン原子、水酸基、炭素数１〜８のアルコキシル基、カルボキシル基、式（２）

[Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxyl group having 1 to 8 carbon atoms, a carboxyl group, a formula (2)

（式中、Ｒ^６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、又は、置換基としてカルボキシル基、アルコキシカルボニル基、アシルオキシル基若しく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、或いは、置換基としてカルボキシル基、アルコキシカルボニル基、アシルオキシル基若しくはアルコキシル基を有していても良い炭素数１〜２４のアルケニル基を表し、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４及びＲ^５の少なくとも一つは水酸基である。］
で表される化合物と式（I）

(In the formula, R ⁶ 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 an alkyl group having 1 to 24 carbon atoms which may have a carboxyl group, an alkoxycarbonyl group, an acyloxyl group or an alkoxyl group as a substituent, or a carboxyl group or an alkoxycarbonyl as a substituent. Represents an alkenyl group having 1 to 24 carbon atoms which may have a group, an acyloxyl group or an alkoxyl group, and at least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is a hydroxyl group. ]
And a compound represented by formula (I)

（式（I）中、Ｘ^１、Ｘ^２は、各々独立して炭素数３〜５のアルキル基を表す。）
又は式（II）

(In formula (I), X ¹ and X ² each independently represents an alkyl group having 3 to 5 carbon atoms.)
Or formula (II)

（式（II）中、Ｘ^３、Ｘ^４は各々独立して炭素数３〜５のアルキル基を表し、Ｘ^５〜Ｘ^８は各々独立して水素原子又は炭素数１〜５のアルキル基を表す。）
で表される化合物を含有する。

(In the formula (II), X ³ and X ⁴ each independently represent an alkyl group having 3 to 5 carbon atoms, and X ^{5 to} X ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. To express.)
The compound represented by these is contained.

[UV curable compound]
As the ultraviolet curable compound used in the present invention, a monofunctional (meth) acrylate, a polyfunctional (meth) acrylate, an oligomer having a (meth) acryloyl group, or the like used for an optical disk can be used in appropriate combination. In addition, in this specification, (meth) acrylate represents an acrylate and a methacrylate, and a (meth) acryloyl group represents an acryloyl group and a methacryloyl group.

Monofunctional (meth) acrylates can be used alone or in combination.
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, ethoxyethoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-chloro-2-hydroxypropyl ( Aliphatic (meth) acrylates such as (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, benzyl (meth) acrylate, nonylphenoxyethyl ( ) Acrylate, tetrahydrofurfuryl (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, nonylphenoxyethyl tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, etc. Aromatic (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, tetracyclododecanyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. Alicyclic (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, acryloylmorpholine, isobornyl (meth) acrylate, norbornyl Meth) acrylate, 2- (meth) acryloyloxy-2-methyl bicycloheptane adamantyl (meth) acrylate, and the like can be used.

  Among the monofunctional (meth) acrylates, isoamyl (meth) acrylate, nonylphenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, caprolactone Modified tetrahydrofurfuryl (meth) acrylate is preferred.

  Of these, tetrahydrofurfuryl acrylate is preferable because of good adhesion to the polycarbonate substrate.

  The content of the monofunctional (meth) acrylate in the total amount of the ultraviolet curable compound contained in the ultraviolet curable composition of the present invention is preferably 1 to 20% by mass, and preferably 1 to 10% by mass. preferable.

The bifunctional (meth) acrylate can be used alone or in combination.
Examples of the bifunctional (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 ( Obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol Diol Di (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, ethylene oxide modified alkylated phosphoric acid di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di ( (Meth) acrylate, polyether (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylate having alicyclic structure, alicyclic bifunctional (meth) acrylate, norbornane dimethanol di (meth) Di (meth) acrylate of diol obtained by adding 2 mol of ethylene oxide or propylene oxide to acrylate, norbornane diethanol di (meth) acrylate, norbornane dimethanol, tricycle Di (meth) acrylate of diol obtained by adding 2 mol of ethylene oxide or propylene oxide to tricyclodecane diethanol di (meth) acrylate, tricyclodecane dimethanol, and pentacyclopentadecane dimethanol Di (meth) acrylate, pentacyclopentadecanediethanol di (meth) acrylate, di (meth) acrylate of diol obtained by adding 2 mol of ethylene oxide or propylene oxide to pentacyclopentadecanedimethanol, ethylene oxide or pentacyclopentadecanediethanol Di (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate of diol obtained by adding 2 mol of propylene oxide, hydroxy Neopentyl glycol di (meth) acrylate, etc. can be used.

  Among the above bifunctional (meth) acrylates, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane di (meta) ) Acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate, and hydroxypivalic acid neopentyl glycol di (meth) acrylate.

  Among these, neopentyl glycol and 1,6-hexanediol diacrylate are preferable because of good adhesion to the polycarbonate substrate.

  The content of the bifunctional (meth) acrylate in the total amount of the ultraviolet curable compound contained in the ultraviolet curable composition of the present invention is preferably 20 to 60% by mass, and preferably 30 to 50% by mass. preferable.

  Further, when it is desired to adjust the elastic modulus after curing to a high level, trifunctional or higher functional (meth) acrylates can be used. For example, bis (2-acryloyloxyethyl) hydroxyethyl isocyanurate, bis (2-acryloyloxypropyl) hydroxypropyl isocyanurate, bis (2-acryloyloxybutyl) hydroxybutyl isocyanurate, bis (2-methacryloyloxyethyl) hydroxy Ethyl isocyanurate, bis (2-methacryloyloxypropyl) hydroxypropyl isocyanurate, bis (2-methacryloyloxybutyl) hydroxybutyl isocyanurate, tris (2-acryloyloxyethyl) isocyanurate, tris (2-acryloyloxypropyl) isocyanate Nurate, Tris (2-acryloyloxybutyl) isocyanurate, Tris (2-methacryloyloxyethyl) isocyanurate , Tris (2-methacryloyloxypropyl) isocyanurate, tris (2-methacryloyloxybutyl) isocyanurate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, penta Diol of triol obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of erythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane Polyfunctional (meth) acrylates such as tri (meth) acrylate and poly (meth) acrylate of dipentaerythritol can be used.

  Of these, a triacrylate of triol obtained by adding 3 mol or more of ethylene oxide to 1 mol of trimethylolpropane is preferable because it has high curability and low cure shrinkage.

  The content of the trifunctional or higher functional (meth) acrylate in the total amount of the ultraviolet curable compound contained in the ultraviolet curable composition of the present invention is preferably 1 to 30% by mass, and preferably 2 to 20% by mass. It is preferable.

  Moreover, ultraviolet curable compounds, such as N-vinyl pyrrolidone, N-vinyl caprolactam, a vinyl ether monomer, can also be used as needed.

  As the oligomer having a (meth) acryloyl group, epoxy (meth) acrylate or urethane (meth) acrylate can be preferably used.

  The epoxy (meth) acrylate is not particularly limited as long as it is obtained by reacting a compound having one or more epoxy groups in the molecule with acrylic acid, and is modified with polyester, polyether, rubber or the like. Also good. The total amount of residual chlorine is preferably 2000 ppm or less.

  Among them, an epoxy (meth) acrylate having a bisphenol skeleton is preferable because of its excellent durability performance, and an epoxy (meth) acrylate represented by the formulas (i), (iii), and (viii) can be particularly preferably used.

[In the formula (i), A ₁ represents the formula (ii)

(In the formula (ii), E ₁ represents —SO ₂ —, —CH ₂ —, —CH (CH ₃ ) — or —C (CH ₃ ) ₂ —, and i ₁ represents 0 or an integer of 1 or more. .)
And each D ₁ independently represents a hydrogen atom or a methyl group. ]

  Examples of such bisphenol type epoxy (meth) acrylate include bisphenol A type epoxy resins such as Epicoat 802, 1001, and 1004 manufactured by Yuka Shell Epoxy, and bisphenol F type epoxy resins such as Epicoat 4001P, 4002P, and 4003P, ) Epoxy acrylate obtained by reaction with acrylic acid, and the like, and UNIDIC V-5810 (Dainippon Ink Chemical Co., Ltd.) are listed.

[In formula (iii), A ₂ may be substituted with an ester group, an ether group, an aromatic hydrocarbon group or a cyclic aliphatic group, and may have a branched chain. 250-10000 long chain alkyl diol groups, B ₁ is of the formula (iv)

(In the formula (iv), _{E 2} is _{-SO 2 -, - CH 2 -} , - CH (CH 3) - or -C _{(CH 3) 2} - represents, _{i 2} represents an integer of 0-8. )
And each D ₂ independently represents a hydrogen atom or a methyl group. ]

A ₂ in the above formula (iii) is preferably a group represented by the formulas (v) to (vii).

(In the formula (v), J ₁ is a divalent aromatic hydrocarbon group in which a hydrogen atom may be substituted with an alkyl group having 1 to 6 carbon atoms or a carbon chain that may have a branched chain. Represents a divalent aliphatic hydrocarbon group having ₁ to 10 carbon atoms, and L ₁ represents a divalent aliphatic hydrocarbon group having 2 to 20 carbon atoms which may have a branched chain, or — (R ² O) _p —. R ² — (R ² represents an optionally substituted alkylene group having 2 to 8 carbon atoms, p is an integer of 1 to 10), and k ₁ is 1 Represents an integer of ~ 20.)

(In formula (vi), J ₂ has ₂ carbon atoms which may have a divalent aromatic hydrocarbon group or branched chain in which a hydrogen atom may be substituted by an alkyl group having 1 to 6 carbon atoms. 10 represents a divalent aliphatic hydrocarbon group of 10 to 10, and L ₂ represents a long-chain alkyl diol residue or a polyether diol residue having a number average molecular weight of 250 to 10,000.

(In formula (vii), J ₃ is a divalent aromatic hydrocarbon group which may have a hydrogen atom substituted by an alkyl group having 1 to 6 carbon atoms or a carbon chain which may have a branched chain. Represents a divalent aliphatic hydrocarbon group having 10 to 10 carbon atoms, and L ₃ and L ₄ each independently represent a divalent aliphatic hydrocarbon group having 2 to 10 carbon atoms which may have a branched chain. , K ₂ and k ₃ each independently represents an integer of 1 to 20.)

  Examples of such an epoxy (meth) acrylate include DICLITE UE-8080 (Dainippon Ink Chemical Co., Ltd.).

[In the formula (viii), A ₃ represents the formula (ix)

(In the formula (ix), _{E 3} is _{-SO 2 -, - CH 2 -} , - CH (CH 3) - or -C _{(CH 3) 2} - represents, n is an integer of 0-8.)
B ₂ is a group represented by the formula (x)

(In the formula (x), J ₅ represents a divalent aromatic may be substituted by an alkyl group having a hydrogen atom having 1 to 6 carbon atoms hydrocarbon group or branched-chain carbon atoms which may have a 2 10 to 10 divalent aliphatic hydrocarbon groups.)
C ₁ is a group represented by the formula (xi)

(L ₅ and L ₆ each independently represent a divalent aliphatic hydrocarbon group having 2 to 10 carbon atoms which may have a branched chain, and k ₄ each independently represents 1 to 20 carbon atoms. (It is an integer.)
Or the formula (xii)

(L ₇ and L ₈ each independently represent a divalent aliphatic hydrocarbon group having 2 to 10 carbon atoms which may have a branched chain, and k ₅ each independently represents 1 to 20 carbon atoms. (It is an integer.)
And D ₃ each independently represents a hydrogen atom or a methyl group. ]

  Examples of such an epoxy (meth) acrylate include CNUVE 151 (SARTOMER), EBECRYL 3708 (Daicel Cytec Co., Ltd.), and the like.

  As a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of the epoxy (meth) acrylate used by this invention, it is preferable that it is 500-20000, and it is more preferable that it is 800-15000. By setting the structure and molecular weight of the epoxy (meth) acrylate within the above ranges, the durability and light resistance of the optical disk using the ultraviolet curable composition of the present invention are further improved. The weight average molecular weight by GPC is, for example, HLC-8020 manufactured by Tosoh Corporation, the column is GMHxl-GMHxl-G200Hxl-G1000Hxlw, the solvent is THF, and the flow rate is 1.0 ml / min. The column temperature is 40 ° C., the detector temperature is 30 ° C., and the molecular weight is specified by performing measurement in terms of standard polystyrene.

  The urethane (meth) acrylate used in the present invention includes a compound having two or more isocyanate groups in the molecule, a compound having a hydroxyl group and a (meth) acryloyl group, and two or more hydroxyl groups in the molecule. A urethane (meth) acrylate obtained from a compound having a diol can be preferably used. Further, urethane (meth) acrylate obtained by reacting a compound having a hydroxyl group and a (meth) acryloyl group with a compound having two isocyanate groups in the molecule can also be preferably used.

  Examples of the compound having two or more isocyanate groups in the molecule include tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone. Examples thereof include polyisocyanates such as diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, and m-phenylene diisocyanate. Among them, a diisocyanate compound having two isocyanate groups in the molecule can be preferably used, and tolylene diisocyanate is particularly preferable because it does not deteriorate the hue and does not decrease the light transmittance.

  Examples of the compound having a hydroxyl group and a (meth) acryloyl group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and these (meth) acrylates and 2 A compound obtained by reacting with a compound having at least one hydroxyl group may also be used. Alternatively, it may be a compound obtained by reacting a compound having two or more hydroxyl groups with (meth) acrylic acid. For example, an addition reaction product of a glycidyl ether compound and (meth) acrylic acid, or a mono (meth) glycol compound (meta) ) Acrylate and the like.

  Polyols are preferably used as the compound having two or more hydroxyl groups, and specific examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3- Propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, eopentyl glycol, 3-methyl-1,5-pentanediol, 2,3,5-trimethyl-1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1, 8-octanediol, trimethylolpropane, pentaerythritol, sorbitol, mannitol, glycerin, 1,2 Dimethylolcyclohexane, 1,3-dimethylolcyclohexane, polymer polyol as multimers such as alkylene polyols such as 1,4-dimethylol cyclohexane.

  Among them, polyether polyols having ether bonds, polyester polyols having ester bonds obtained by reaction with polybasic acids and ring-opening polymerization of cyclic esters, or polycarbonate polyols having carbonate bonds obtained by reaction with carbonates. Preferably there is. At least a part of these polyols, preferably 15 mol% or more in the total amount of polyols, more preferably 30 mol% or more in the total amount of polyols, preferably has a molecular weight of 500-2500.

  Examples of the polyether polyol include polytetramethylene glycol as a ring-opening polymer of a cyclic ether such as tetrahydrofuran, in addition to the multimers of the polyols, and ethylene polyol, propylene oxide, 1 2, 2-butylene oxide, 1,3-butylene oxide, 2,3-butylene oxide, tetrahydrofuran, styrene oxide, adducts of alkylene oxide such as epichlorohydrin, and the like.

  Examples of the polyester polyol include a reaction product of the above polyols with a polybasic acid such as maleic acid, fumaric acid, adipic acid, sebacic acid, and phthalic acid, and a ring-opening polymer of a cyclic ester such as caprolactone. Examples include polycaprolactone.

  As the polycarbonate polyol, for example, the above polyols, alkylene carbonate such as ethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate, or diphenyl carbonate, 4-methyl diphenyl carbonate, 4-ethyl diphenyl carbonate, 4-propyl diphenyl carbonate, 4,4'-dimethyl diphenyl carbonate, 2-tolyl-4-tolyl carbonate, 4,4'-diethyl diphenyl carbonate, 4,4'-dipropyl diphenyl carbonate, phenyl toluyl carbonate, bischlorophenyl carbonate Diaryl carbonates such as phenyl chlorophenyl carbonate, phenyl naphthyl carbonate, dinaphthyl carbonate, or dimethyl Reaction with dialkyl carbonates such as carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, di-n-butyl carbonate, diisobutyl carbonate, di-t-butyl carbonate, di-n-amyl carbonate, diisoamyl carbonate, etc. Thing etc. are mentioned.

  The polyol to be used may be one kind or two or more kinds may be used in combination, but urethane (meth) acrylate using two or more kinds of polyether polyol, polyester polyol and polycarbonate polyol is preferable, and two kinds are used in combination. More preferably. By using these polyols in combination, it becomes easy to suitably adjust the deformation resistance and surface hardness of the obtained cured film in a high temperature and high humidity environment. As an example of two types of combined use, in the case of increasing the surface hardness, the combined use of polyester polyol and polycarbonate polyol is preferable, and in the case of improving the heat and humidity resistance, it is preferable to use a polyether polyol in combination. . In order to achieve these intermediate characteristics, it is preferable to use a polyether polyol and a polycarbonate polyol in combination.

  As content of each polyol at the time of polyol combined use, it is preferable that polyether polyol is 20-90 mass% with respect to the whole quantity of the polyol to be used, and it is more preferable that it is 30-80 mass%. As content of polyester polyol, it is preferable that it is 10-70 mass%, and it is more preferable to set it as 20-60 mass%. By making content of polyether polyol or polyester polyol into the said range, the surface hardness and heat-and-moisture resistant property of hardened | cured material are easy to be obtained.

  In addition, the urethane (meth) acrylate used in the present invention is preferably a structure having no aromatic ring, since the transparency becomes high.

  The urethane (meth) acrylate used in the present invention is a polyether skeleton urethane acrylate, manufactured by Dainippon Ink & Chemicals, Inc., FAU-742TP, FAU-306, a polyester skeleton urethane acrylate, Cognis Japan Co., Ltd. ) Photomer 6892 manufactured by the company, Ebecryl-8405 manufactured by Daicel Cytec Co., Ltd. and the like can be preferably exemplified.

  The content of the urethane (meth) acrylate in the ultraviolet curable composition of the present invention is preferably 5 to 20% by mass in the ultraviolet curable compound contained in the ultraviolet curable composition, and 5 to 15% by mass. It is particularly preferred that By setting the urethane (meth) acrylate content in the above range, it is possible to impart an appropriate flexibility to the cured film, and in particular, a change in warp when a humidity shock is applied becomes small.

  As a weight average molecular weight (Mw) measured by the gel permeation chromatography (GPC) of urethane (meth) acrylate used by this invention, it is preferable that it is 1000-20000, and it is more preferable that it is 1500-10000. Thereby, the durability and light resistance of the optical disk using the ultraviolet curable composition of the present invention are further improved.

  In the present invention, it is preferable to contain an epoxy (meth) acrylate as an oligomer having a (meth) acryloyl group, and when it contains an epoxy (meth) acrylate, the content is included in the ultraviolet curable composition. It is preferable that it is 5-60 mass% in the total amount of the ultraviolet curable compound to be produced, and it is preferable that it is 10-50 mass%. By controlling the content of epoxy (meth) acrylate within this range, in addition to excellent durability in high-temperature and high-humidity environments, it is preferable to control properties such as reducing warpage during curing and in high-temperature and high-humidity environments. Can do.

  Moreover, in order to adjust the characteristics of the resulting cured film, other various (meth) acryloyl group-containing oligomers may be contained, but the content of other oligomers is preferably 40% by mass or less. 30% by mass or less is preferable.

[Phenolic hydroxyl group-containing compound]
In the ultraviolet curable composition for optical disks of the present invention, by containing the compound represented by the formula (1), the initial adhesive force of the cured film of the ultraviolet curable composition can be increased, The optical disk of the present invention can be considerably prevented from lowering the adhesive strength after being left in a high-temperature and high-humidity environment for a long time, changing the appearance of the reflective film, and increasing signal reading errors.

［式中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４及びＲ^５は各々独立して、水素原子、ハロゲン原子、水酸基、炭素数１〜８のアルコキシル基、カルボキシル基、式（２）

[Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxyl group having 1 to 8 carbon atoms, a carboxyl group, a formula (2)

（式中、Ｒ^６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、又は、置換基としてカルボキシル基、アルコキシカルボニル基、アシルオキシル基若しく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、或いは、置換基としてカルボキシル基、アルコキシカルボニル基、アシルオキシル基若しくはアルコキシル基を有していても良い炭素数１〜２４のアルケニル基を表し、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４及びＲ^５の少なくとも一つは水酸基である。］

(In the formula, R ⁶ 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 an alkyl group having 1 to 24 carbon atoms which may have a carboxyl group, an alkoxycarbonyl group, an acyloxyl group or an alkoxyl group as a substituent, or a carboxyl group or an alkoxycarbonyl as a substituent. Represents an alkenyl group having 1 to 24 carbon atoms which may have a group, an acyloxyl group or an alkoxyl group, and at least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is a hydroxyl group. ]

  The compound represented by the formula (1) includes compounds having various structures, and among them, gallic acid or gallic acid ester represented by the following formula (3) is preferable.

（式中、Ｒ^７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。）

(Wherein R ⁷ 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.)

The alkyl group and alkenyl group 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 ⁷ 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.

  Specific examples of gallic acid esters include methyl gallate, ethyl gallate, propyl gallate, isopropyl gallate, isopentyl gallate, octyl gallate, dodecyl gallate, tetradecyl gallate, hexadecyl gallate, octadecyl gallate Etc. As the compound represented by the formula (3), gallic acid is preferably used.

  Moreover, as a compound represented by said Formula (1), the compound represented by following formula (4) is also preferable.

（式中、Ｒ^８、Ｒ^９、Ｒ^１０及びＲ^１１は各々独立して、水素原子、ハロゲン原子、炭素数１〜８のアルコキシル基、又は、置換基として−ＣＯＯＨ、−ＣＯＯＲ^１２、−ＯＣＯＲ^１３若しくは−ＯＲ^１４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、−ＣＯＯＲ^１２、−ＯＣＯＲ^１３若しくは−ＯＲ^１４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、Ｒ^１２、Ｒ^１３及びＲ^１４は、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 ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹² , —OCOR as a substituent. ¹³ or -OR ¹⁴ may have an alkyl group having 1 to 24 carbon atoms, or -COOH, -COOR ¹² , -OCOR ¹³ or -OR ¹⁴ as a substituent may have 1 carbon atom. (In formula, R < ¹² >, R < ¹³ > and R < ¹⁴ > represent a C1-C8 alkyl group or a C1-C8 alkenyl group.).

In the formula (4), R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are specifically a halogen atom such as a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, methoxy, ethoxy, butoxy or octyloxy An alkoxyl group such as methyl, butyl, hexyl, octyl, lauryl or octadecyl, an alkenyl group such as ethenyl, propenyl or 2-butenyl, 4-carboxybutyl, 2-methoxycarbonylethyl, methoxymethyl or ethoxy And methyl.

  Among the compounds represented by the formula (4), 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.

  Furthermore, as a compound represented by said Formula (1), the compound represented by following formula (5) and Formula (6) is also preferable.

（式中、Ｒ^１５、Ｒ^１６、Ｒ^１７及びＲ^１８は各々独立して、水素原子、ハロゲン原子、炭素数１〜８のアルコキシル基、又は、置換基として−ＣＯＯＨ、−ＣＯＯＲ^１２、−ＯＣＯＲ^１３若しくは−ＯＲ^１４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、−ＣＯＯＲ^１２、−ＯＣＯＲ^１３若しくは−ＯＲ^１４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、Ｒ^１２、Ｒ^１３及びＲ^１４は、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 ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹² , —OCOR as a substituent. ¹³ or -OR ¹⁴ may have an alkyl group having 1 to 24 carbon atoms, or -COOH, -COOR ¹² , -OCOR ¹³ or -OR ¹⁴ as a substituent may have 1 carbon atom. (In formula, R < ¹² >, R < ¹³ > and R < ¹⁴ > represent a C1-C8 alkyl group or a C1-C8 alkenyl group.).

（式中、Ｒ^１９、Ｒ^２０、Ｒ^２１及びＲ^２２は各々独立して、水素原子、ハロゲン原子、炭素数１〜８のアルコキシル基、又は、置換基として−ＣＯＯＨ、−ＣＯＯＲ^１２、−ＯＣＯＲ^１３若しくは−ＯＲ^１４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、−ＣＯＯＲ^１２、−ＯＣＯＲ^１３若しくは−ＯＲ^１４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、Ｒ^１２、Ｒ^１３及びＲ^１４は、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。）。）

(In the formula, R ¹⁹ , R ²⁰ , R ²¹ and R ²² are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹² , —OCOR as a substituent. ¹³ or -OR ¹⁴ may have an alkyl group having 1 to 24 carbon atoms, or -COOH, -COOR ¹² , -OCOR ¹³ or -OR ¹⁴ as a substituent may have 1 carbon atom. (In formula, R < ¹² >, R < ¹³ > and R < ¹⁴ > represent a C1-C8 alkyl group or a C1-C8 alkenyl group.).

R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ in formula (5) and R ¹⁹ , R ²⁰ , R ²¹ , R ²² in formula (6) 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 (5), 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. Among the compounds represented by the formula (6), resorcinol (benzone-1,3-diol) and orcinol (5-methylbenzene-1,3-diol) are preferable. Among these, the compound represented by the formula (5) is more preferable than the compound represented by the formula (6), and among the compounds represented by the formula (5), 2,5-di-tert-butyl is preferred. It is more preferable to use hydroquinone. Further, as the compound represented by the formula (1), another compound that is preferably used in the present invention is pyrogallol (1,2,3-trihydroxybenzene).

  Among the compounds represented by the above formulas (3) to (6), the gallic acid or gallic acid ester represented by the formula (3) and the hydroquinone compound represented by the formula (5) are high temperature and high humidity. It is a particularly preferable compound among the compounds represented by the formula (1) because it can particularly improve durability in the environment. Of the compounds represented by formula (3) and formula (5), gallic acid is the most preferred compound.

  The content of the compound represented by the formula (1) in the ultraviolet curable composition is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the ultraviolet curable compound. 10 parts by mass. It is still more preferable that it is 0.3-7 mass parts, and it is especially preferable that it is 1-5 mass parts.

[Compound having phenolic hydroxyl group and adjacent alkyl group]
The ultraviolet curable composition for optical discs of the present invention contains a compound having a phenolic hydroxyl group and an adjacent alkyl group represented by the following formula (I) or formula (II).

（式（I）中、Ｘ^１、Ｘ^２は、各々独立して炭素数３〜５のアルキル基を表す。）

(In formula (I), X ¹ and X ² each independently represents an alkyl group having 3 to 5 carbon atoms.)

（式（II）中、Ｘ^３、Ｘ^４は各々独立して炭素数３〜５のアルキル基を表し、Ｘ^５〜Ｘ^８は各々独立して水素原子又は炭素数１〜５のアルキル基を表す。）

(In the formula (II), X ³ and X ⁴ each independently represent an alkyl group having 3 to 5 carbon atoms, and X ^{5 to} X ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. To express.)

  The ultraviolet curable composition of the present invention contains a compound having the phenolic hydroxyl group and an adjacent alkyl group, thereby preventing deterioration of the cured film under high temperature and high humidity, and peeling of the cured film from the light reflecting layer. Can be sufficiently suppressed. Furthermore, by using together the compound which has the said phenolic hydroxyl group and adjacent alkyl group with the phenolic hydroxyl group containing compound represented by said Formula (1), by preventing the oxidation of the phenolic hydroxyl group which is easy to oxidize, both compounds of It is considered that the excellent deterioration preventing function can be expressed synergistically.

  Especially, since the compound represented by the following formula (III) or formula (IV) is oxidized prior to the phenolic hydroxyl group-containing compound represented by the above formula (1), it is preferable.

  The content of the compound represented by formula (I) or formula (II) in the ultraviolet curable composition is preferably 0.01 to 5 parts by mass, more preferably 100 parts by mass of the ultraviolet curable compound. Is 0.01 to 3 parts by mass, particularly preferably 0.01 to 2 parts by mass. When using together the compound represented by Formula (I) and Formula (II), it is preferable that the sum total is the said range.

[Initiator, additive, etc.]
In the ultraviolet curable composition for optical disks of the present invention, in addition to epoxy (meth) acrylate and the above monofunctional, bifunctional or polyfunctional (meth) acrylate, known photopolymerization initiators, thermal polymerization initiators, etc. Can be used.

  Examples of the photopolymerization initiator that can be 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 There are molecular cleavage types such as morpholinopropan-1-one and hydrogen abstraction type photopolymerization initiators such as benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4′-methyl-diphenyl sulfide.

  In the ultraviolet curable composition used in the present invention, as necessary, surfactants, leveling agents, thermal polymerization inhibitors, hindered phenols, phosphites and other antioxidants, hindered amines and other light Stabilizers can also be used. 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.

  The ultraviolet curable composition of the present invention is suitable for a thick light-transmitting layer by adjusting the blending of the ultraviolet curable compound and the like, and having a viscosity of 200 to 1000 mPa · s, preferably 300 to 700 mPa · s. Can be formed.

  It is preferable that the ultraviolet curable composition of this invention adjusts so that the elasticity modulus of the cured film after irradiating an ultraviolet-ray may be 1000-4000 Mpa (25 degreeC). Among these, a composition of 1500 to 3500 MPa is more preferable. When the composition has an elastic modulus in this range, distortion at the time of curing is easily relaxed, and an optical disc with little change in warpage can be obtained even when exposed to a high temperature and high humidity environment for a long time.

[optical disk]
The optical disk of the present invention comprises a reflective layer for reflecting laser light for reading information on a substrate, and further a layer (hereinafter referred to as a cured film layer) made of a cured film of the ultraviolet curable composition on the reflective layer. Or an information recording layer for recording a signal between the reflective layer and the cured film layer. The optical disk of the present invention is an optical disk having such a structure, or an optical disk partially having such a structure. The former is a read-only optical disk, and the latter is a recordable optical disk capable of recording and reproducing information. is there.

  As such an optical disc, 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.

  The optical disk of the present invention may have a structure in which a plurality of information recording sites are laminated, on a cured film layer made of the cured film of the ultraviolet curable composition provided on the first reflective film. Further, a second substrate provided with a second reflective film for reflecting laser light for reading information is provided on the resin layer so that the resin layer and the second reflective film are in contact with each other. It may be an optical disc having the structure described above. 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 used in the present invention, those usually used as optical disk substrates can be used, and in particular, a polycarbonate substrate can be suitably used. When the optical disc is read-only, pits for recording information are formed on the surface of the substrate that is laminated with the light reflecting layer.

  The cured film layer in the optical disk of the present invention is made of the ultraviolet curable composition, and is unlikely to cause discoloration or deformation in a high temperature and high humidity environment. The cured film layer preferably has a reflectance change amount of 4.0% or less and particularly preferably 2.0% or less when exposed to a fluorescent lamp for 10 days when the thickness is 100 μm.

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
In the case of a writable optical disc, an information recording layer is provided between the light reflecting layer and the light transmitting layer. The information recording layer only needs to be capable of recording / reproducing information, and may be any of a phase change recording layer, a magneto-optical recording layer, and an organic dye recording layer.

When the information recording layer is a phase change recording layer, the information recording layer is usually composed of a dielectric layer and a phase change film. The dielectric layer is required to have a function of buffering heat generated in the phase change layer and a function of adjusting the reflectivity of the disk, and a mixed composition of ZnS and SiO ₂ is used. The phase change film causes a difference in reflectance between the amorphous state and the crystalline state due to the phase change of the film, and uses a Ge—Sb—Te, Sb—Te, or Ag—In—Sb—Te alloy. Can do.

  The organic dye used for the organic dye-type recording layer can be used without particular limitation as long as it can form pits by laser light used for recording, in addition to the azo dye, for example, cyanine, phthalocyanine, and naphthalene. Examples include phthalocyanine series, anthraquinone series, triphenylmethane series, pyrylium or thiapyrylium salt series, squarylium series, croconium series, formazan series, and metal complex dye series. In addition, a singlet oxygen quencher may be mixed with the dye. The quencher is preferably a metal complex such as acetylacetonate, bisdithio-α-diketone, bisdithiol such as bisphenyldithiol, thiocatechol, salicylaldehyde oxime, or thiobisphenolate. An amine quencher such as an amine compound having a nitrogen radical cation or a hindered amine is also suitable. The material used for each information recording layer may be the same or different.

  When the ultraviolet curable composition applied on the light reflecting layer is cured by irradiating with ultraviolet rays, for example, it can be performed by a continuous light irradiation method using a metal halide lamp, a high-pressure mercury lamp, or the like, It can also be done. The flash irradiation method is more preferable in that it can be cured efficiently.

When irradiating with ultraviolet rays, it is preferable to control the accumulated light amount to be 0.05 to 1 J / cm ² . More preferably accumulated light amount is 0.05~0.8J / cm ^2, and particularly preferably 0.05~0.6J / cm ^2. The ultraviolet curable composition used for the optical disk of the present invention is sufficiently cured even when the integrated light quantity is small, and does not cause tacking of the end face or surface of the optical disk, and further does not cause warping or distortion of the optical disk.

[Embodiment]
The type of the optical disk of the present invention is preferably a writable DVD-R, DVD + R, rewritable DVD-RW, DVD + RW, DVD-RAM, or other DVD, particularly preferably “DVD-9” and “DVD”. -18 ".

  In addition, the optical disk of the present invention is not limited to these, for example, on a thin film of an optical disk substrate having a thickness of about 1.1 mm, for example, silver or a silver-based alloy as a main component. In addition, a protective layer or cover layer having a thickness of about 0.1 mm or a light transmission layer may be formed, that is, a type suitable for blue-violet laser light as a laser light for reading and writing information, or a DVD A SACD (Super Audio CD) having a structure in which two substrates having a thickness of 0.6 mm, which are similar to those in FIG.

  Hereinafter, examples of manufacturing “DVD-5”, “DVD-10”, “DVD-9”, and “DVD-18” will be described. Examples of the optical disc of the present invention are not limited to these. Moreover, the ultraviolet curable composition used by the following manufacture example means the ultraviolet curable composition containing the compound represented by the said Formula (1) used by this 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 1-4 and Comparative Examples 1-4)
According to the composition shown in Table 1 below, each composition raw material was heated and dissolved at 60 ° C. for 3 hours to prepare UV curable compositions of Examples and Comparative Examples.
Table 1 shows the results of evaluating the compositions of Examples and Comparative Examples using the obtained ultraviolet curable compositions by the following test methods and the like. In addition, the numerical value of the composition in a table | surface represents a mass part.

<Test method: Durability test of DVD-R bonded optical disk>
Using the UV curable composition dispenser of each of the above examples and comparative examples, a land / groove was formed, and a recording layer of an organic dye and a polycarbonate disk in which a reflective film made of an alloy mainly composed of silver was sequentially laminated. A transparent polycarbonate disk was overlaid. Subsequently, it was rotated with a spin coater so that the film thickness of the cured coating film was 50 to 60 μm. Next, a DVD-R sample using each composition by irradiating 7 shot ultraviolet rays in air from the transparent substrate side at a set voltage of 1450 V using “Xenon flash irradiation device SBC-17 type” manufactured by USHIO INC. Was made.

  Using the GL-30 manufactured by Expert Corporation, the produced disc is 4 times faster in the inner circumference (Position: 24.50-25.00 mm) and middle circumference (Position: 40.03-40.51 mm). I wrote. The PI error count is the average value of the inner and middle circumference measured values.

  The number of PI errors of each sample obtained was measured, and then an environmental test at 80 ° C. and 85% RH 480 hours was performed using “Etac constant temperature and high humidity device SD01” manufactured by Espec. After the test, the number of PI errors in each sample was measured.

The number of PI errors was measured by “SA-300” manufactured by Audio Dev Co., Ltd. As a recording device, “DVR-106” manufactured by Pioneer Corporation was used. The PI error ratio (number of PI errors after the environmental test / number of PI errors before the environmental test) was determined from the number of PI errors before and after the environmental test.
○ When the PI error ratio is 15 or less
The case where the PI error ratio exceeded 15 was marked as x.

<Measurement method of elastic modulus>
An ultraviolet curable composition was applied on a glass plate so that the cured coating film would be 100 ± 10 μm, and then 0.5 J / cm in a nitrogen atmosphere using a metal halide lamp (with a cold mirror, lamp output 120 W / cm). ² to cure. The elastic modulus of this cured coating film was measured with an automatic dynamic viscoelasticity measuring device manufactured by TA Instruments Co., Ltd., and the dynamic elastic modulus E ′ at 25 ° C. was defined as the elastic modulus.

The compounds in Table 1 are as follows.
Bis-A type DA: bisphenol A type epoxy acrylate Photomer 3016 (manufactured by Cognis Japan Co., Ltd., weight average molecular weight Mw: 1300)
FAU-742TP: Urethane acrylate Dainippon Ink & Chemicals, Inc. weight average molecular weight Mw: 3700
TMP (3EO) TM: triol triacrylate obtained by adding 3 mol of ethylene oxide to 1 mol of trimethylolpropane NPGDA: neopentyl glycol diacrylate HDDA: 1,6-hexanediol diacrylate DPGDA: dipropylene glycol di Acrylate BPE (EO) 4DA: Diacrylate of bisphenol A ethylene oxide 4 mol adduct THFA: Tetrahydrofurfuryl acrylate PEA: Phenoxyethyl acrylate Phosphate methacrylate: Ethylene oxide-modified phosphate dimethacrylate PM-2 Made)
HCPK: 1-hydroxycyclohexyl phenyl ketone TPO: trimethylphenyldiphenylphosphine oxide simulator WX-R: 4,4′-thiobis (6-tert-butyl-3-methylphenol) (manufactured by Sumitomo Chemical Co., Ltd.)
IRGANOX 1520L: 2,4-bis [(octylthio) methyl] -o-cresol (Ciba Specialty Chemicals Co., Ltd.)

  As shown in Table 1, the optical disks of Examples 1 to 4 prepared by blending the compounds represented by the formula (1) and the formula (I) or the formula (II), which are the compositions of the present invention, have PI errors. The ratio was small, and the durability under high temperature and high humidity environment was good. On the other hand, including the compound represented by the formula (1) but not the compound represented by the formula (I) or (II), including the compound represented by the comparative example 1 and the formula (1), the number of substituents Is represented by Comparative Example 2 containing a compound less than the compound represented by Formula (I), Comparative Example 3 containing only the compound represented by Formula (II) but not Formula (1), and Formula (1) Comparative Example 4 containing a compound but containing a compound other than the formula (II) had a large PI error ratio and was not durable under a high temperature and high humidity environment.

Claims (9)

UV curable compound and formula (1)

[Wherein R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxyl group having 1 to 8 carbon atoms, a carboxyl group, a formula (2)

(In the formula, R ⁶ 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 an alkyl group having 1 to 24 carbon atoms which may have a carboxyl group, an alkoxycarbonyl group, an acyloxyl group or an alkoxyl group as a substituent, or a carboxyl group or an alkoxycarbonyl as a substituent. Represents an alkenyl group having 1 to 24 carbon atoms which may have a group, an acyloxyl group or an alkoxyl group, and at least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is a hydroxyl group. ]
And a compound of formula (I)

(In formula (I), X ¹ and X ² each independently represents an alkyl group having 3 to 5 carbon atoms.)
Or formula (II)

(In the formula (II), X ³ and X ⁴ each independently represent an alkyl group having 3 to 5 carbon atoms, and X ^{5 to} X ⁸ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. To express.)
An ultraviolet curable composition for optical discs containing a compound represented by the formula: The ultraviolet curable composition according to claim 1, wherein the content of the compound represented by the formula (I) or the formula (II) is 0.01 to 5 parts by mass with respect to 100 parts by mass of the ultraviolet curable compound. object. The ultraviolet curable composition according to claim 1 or 2, wherein the content of the compound represented by the formula (1) is 0.05 to 10 parts by mass with respect to 100 parts by mass of the ultraviolet curable compound. The compound represented by the formula (1) is represented by the formula (3),

(In formula (3), R ⁷ 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. To express.)
Formula (4),

Wherein R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹² , —OCOR as a substituent. ¹³ or -OR ¹⁴ may have an alkyl group having 1 to 24 carbon atoms, or -COOH, -COOR ¹² , -OCOR ¹³ or -OR ¹⁴ may be substituted as a carbon number 1 -24 represents an alkenyl group (wherein R ¹² , R ¹³ and R ¹⁴ represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms).
Formula (5)

Wherein R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹² , —OCOR as a substituent. ¹³ or -OR ¹⁴ may have an alkyl group having 1 to 24 carbon atoms, or -COOH, -COOR ¹² , -OCOR ¹³ or -OR ¹⁴ as a substituent may have 1 carbon atom. (In formula, R < ¹² >, R < ¹³ > and R < ¹⁴ > represent a C1-C8 alkyl group or a C1-C8 alkenyl group.).
Or formula (6)

(In the formula, R ¹⁹ , R ²⁰ , R ²¹ and R ²² are each independently a hydrogen atom, a halogen atom, an alkoxyl group having 1 to 8 carbon atoms, or —COOH, —COOR ¹² , —OCOR as a substituent. ¹³ or -OR ¹⁴ may have an alkyl group having 1 to 24 carbon atoms, or -COOH, -COOR ¹² , -OCOR ¹³ or -OR ¹⁴ as a substituent may have 1 carbon atom. -24 represents an alkenyl group (wherein R ¹² , R ¹³ , and R ¹⁴ represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 1 to 8 carbon atoms).
The ultraviolet curable composition for optical discs according to any one of claims 1 to 3, which is a compound represented by the formula: The compound represented by the formula (1) 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 optical device according to any one of claims 1 to 3. Risk for ultraviolet-curable composition. The compound represented by the formula (I) is represented by the formula (III)

The ultraviolet curable composition for optical discs according to any one of claims 1 to 5, wherein The compound represented by the formula (II) is represented by the formula (IV)

The ultraviolet curable composition for optical discs according to any one of claims 1 to 5, wherein The substrate has a light reflecting layer made of silver or an alloy containing silver as a main component for reflecting laser light for reading information, and a layer made of a cured film of an ultraviolet curable composition is provided on the reflecting layer. An optical disc,
An optical disc, wherein the ultraviolet curable composition is the ultraviolet curable composition for optical discs according to any one of claims 1 to 7. A light reflecting layer made of silver or an alloy containing silver as a main component for reflecting laser light for reading information on a substrate is provided, and an information recording layer is provided on the reflecting layer. An optical disk comprising a layer comprising a cured film of an ultraviolet curable composition, wherein the ultraviolet curable composition is the ultraviolet curable composition for optical disks according to any one of claims 1 to 7. An optical disc.