JP2007056047A - Ultraviolet light curable type composition for optical disc and optical disc by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet light curable type composition for an optical disc, capable of forming a resin layer used between a semi-transparent reflective layer and a pigment-recording layer of a multi-layered rerecording type optical disc, and without generating the reading error of a signal even on being heated by a laser beam in writing the signal. <P>SOLUTION: This ultraviolet light curable type composition for the optical disc containing a radically polymerizable compound is characterized by containing (1) a compound A having a radically polymerizable unsaturated double bond and a multiple ring type structure in the same molecule, (2) a compound B having a radically polymerizable unsaturated double bond and a tri-valent partial structure of an isocyanulate ring in the same molecule and (3) a compound C having ≥3 (meth)acryloyl groups and ≤250 molecular weight for each one of the (meth)acryloyl groups. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultraviolet curable composition for optical discs, and more particularly to an ultraviolet curable composition used for an optical disc having a structure in which a recording layer is provided in multiple layers, and an optical disc using the composition.

  A typical example of the bonded optical disk is a DVD (digital versatile disk or digital video disk). In this DVD, an optical disk substrate having a recording layer and an optical disk substrate having no information recording, or two disk substrates having a recording layer are connected via an intermediate resin layer. Are joined together.

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

  2. Description of the Related Art Conventional write-once DVDs are obtained by joining an optical disk substrate in which a recording layer made of an organic dye and a light reflection layer are laminated on a substrate and an optical disk substrate having no information recording layer. 1 was provided with one recording layer. In order to increase the recording capacity of an optical disc, an optical disc in which a plurality of recording layers are provided on one optical disc has been proposed. (For example, Patent Document 1) That is, it is formed of a light reflecting layer on the first optical recording surface formed from a dye recording layer and a light reflecting layer provided on a substrate, and another dye recording layer and a light reflecting layer. A multilayer optical disc is shown in which a dye recording layer on the second optical recording surface is bonded with a light-transmitting intermediate layer interposed therebetween. According to the optical disk described in this document, it is possible to irradiate a laser beam from one side, and to record and reproduce the recording layer on the first optical recording surface and further the recording layer on the second optical recording surface through the intermediate layer. It is. In addition, a method for manufacturing a multilayer write-once optical disc has been proposed in which an intermediate layer that joins the first optical recording surface and the second optical recording surface has a structure in which a plurality of resin layers are laminated. (For example, Patent Document 2) In these multilayer write-once optical discs, as described above, signals are recorded by irradiating an organic dye or the like with laser light. In this case, the organic dye or the like is locally heated and becomes a high temperature to cause a chemical change. At the same time, the peripheral portion including the intermediate layer is also heated. When this intermediate layer is formed of a cured layer of an ultraviolet curable composition, the composition is designed so that the cured layer is not deformed by local heating during laser writing and does not interfere with reading of the recorded signal. There is a need to do.

  By the way, the technique regarding the active energy ray curable composition for optical disks which uses an isocyanurate type compound and the compound which has a cyclic skeleton together is known (for example, refer patent document 3). This technique relates to an active energy ray-curable composition for optical discs that can form a cured product layer having a low curing shrinkage during polymerization and having a low water absorption rate and excellent transparency. A composition containing 10% by mass of (2-acryloyloxyethyl) isocyanurate and 10% by mass of tricyclodecane dimethanol diacrylate is also described, and this composition is used to protect an optical disk having an aluminum alloy reflective film. However, this patent document describes a read-only optical disc, particularly a Blu-ray optical disc having a protective layer with a thickness of about 100 microns, and a composition for forming the protective layer. This is only a matter of information about the multilayer write-once optical disc, especially the intermediate layer of the multilayer write-once optical disc. There is no description about the fact that a part is deformed by heating at the time of signal writing by the zigzag light, so that a PI error, a jitter error, a decrease in reflectance, etc. occur at the time of reading the signal. In addition, there is no description regarding the behavior of the composition described in the patent document during heating, and there is no description suggesting them, and therefore, the composition described in the patent document has a multilayer write-once type. The effectiveness of using it as an intermediate layer composition for optical discs was completely unpredictable.In fact, when this composition was used as an intermediate layer composition for multilayer write-once optical discs, a signal from a laser beam was used. Due to heating during writing, part of the intermediate layer is deformed, which increases PI error and jitter when reading signals, which is practically satisfactory. That it was difficult to obtain a multi-layer write-once optical disc.

JP 2003-331463 A JP 2003-77191 A JP 2003-119231 A

  Therefore, an object of the present invention is to be used between a translucent reflective layer and a dye recording layer of a multilayer write-once optical disc, and even when heated by a laser beam at the time of signal writing, deformation is not likely to occur. Another object of the present invention is to provide an ultraviolet curable composition for an optical disc capable of forming a resin layer that does not cause a signal reading error. Another object of the present invention is to provide a multi-layer write-once optical disc with good recording characteristics that does not cause signal reading errors even when heated by laser light during signal writing. It is.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is an ultraviolet curable composition for optical disks containing a radical polymerizable compound,
(1) Compound A having a radical polymerizable unsaturated double bond and a polycyclic structure in the same molecule,
(2) Radical polymerizable unsaturated double bond and formula I in the same molecule

で表される３価の部分構造を有する化合物Ｂ、及び
（３）３以上の（メタ）アクリロイル基を有し、且つ該（メタ）アクリロイル基１個当たりの分子量が２５０以下である化合物Ｃ
を含有す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。

And (3) a compound C having 3 or more (meth) acryloyl groups and a molecular weight of 250 or less per (meth) acryloyl group
The present invention provides an ultraviolet curable composition for optical discs, which contains

The present invention also provides a dye recording layer (a ₁ ), a translucent light reflecting layer (t ₁ ), a cured resin layer (c ₁ ) of the ultraviolet curable composition for optical discs described above, and a dye recording layer (b ) And a light reflection layer (r) are provided in an optical disc having a structure in which the layers are laminated in this order.

  The cured film of the ultraviolet curable composition for optical disks of the present invention is presumed to act on the signal characteristics of the optical recording surface as follows. When a signal is recorded on the optical recording surface with laser light, the dye recording layer is irradiated with laser light to chemically change the dye at a high temperature. At this time, the resin layer in contact with the dye recording layer on the optical recording surface also receives heat due to the chemical change of the laser and the dye, but the resin layer composed of the cured film of the ultraviolet curable composition for optical discs of the present invention, Since the compound A, the compound B, and the compound C are contained, a high glass transition temperature is obtained, the fluid is extremely difficult to flow even at a high temperature, and deformation due to the heat hardly occurs even when receiving heat during recording. Therefore, the groove formed in the resin layer is not deformed, the signal mark is sharp, and excellent signal characteristics can be obtained.

  Since the ultraviolet curable composition for optical discs of the present invention contains the compound A, the compound B and the compound C, the deformation of the cured resin layer can be achieved even when heated by laser light during signal writing. Is unlikely to occur. Accordingly, it is possible to obtain a multilayer write-once optical disc with good recording characteristics that does not cause a signal reading error.

  The compound A having a radical polymerizable unsaturated double bond and a polycyclic structure in the same molecule used in the ultraviolet curable composition for optical discs of the present invention has high rigidity due to the polycyclic structure in the molecule. Thus, it can withstand high temperatures during laser recording, prevent the resin layer from being deformed, and give the resin layer excellent moisture and heat resistance to provide long-term reliability of the dye recording layer. In the present specification, (meth) acrylic acid refers to acrylic acid or methacrylic acid, and the same applies to derivatives of acrylic acid or methacrylic acid.

  As the compound A, compounds having various structures can be used. For example, a compound represented by the formula (XI), a compound having a structure in which the bisphenol A structure portion in the formula (XI) is replaced with a hydrogenated bisphenol A structure, dicyclo (meth) acrylic acid tricyclodecane dimethanol, (meth) Isobornyl acrylate, norbornyl (meth) acrylate, 2- (meth) acryloyloxymethyl-2-methylbicycloheptane, adamantyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopenta (meth) acrylate Nyl, (meth) acrylic acid tetracyclododecanyl and the like.

（式中、Ｒ_１及びＲ_２は、同一又は異なっていても良く、エチレン基又はプロピレン基を示し、Ｚ_１及びＺ_２は、同一又は異なっていても良く、水素原子又はメチル基を示し、ｍ及びｎは、同一又は異なっていても良く、１〜９の整数を示し、かつｍ＋ｎは２〜１０の整数を示す。）

(Wherein R ₁ and R ₂ may be the same or different and each represents an ethylene group or a propylene group; Z ₁ and Z ₂ may be the same or different and each represents a hydrogen atom or a methyl group; m and n may be the same or different, and represent an integer of 1 to 9, and m + n represents an integer of 2 to 10.)

Among the compounds A, compounds having a more preferable structure include compounds represented by the following formula (II).
^{X 1 -R 1 -O-R 2} -O-R 3 -X 1 (II)
(Wherein X ¹ represents the formula (III)

（式中、Ｚは水素原子又はメチル基を表す。）で表される基であり、Ｒ^１及びＲ³は-(OC_nH_2n)_m-（式中、ｎは１〜４の整数を表し、ｍは１又は２を表し、式中の酸素原子はＸ^１と結合する。）で表される基であり、Ｒ^２は、式(IV)、

(Wherein Z represents a hydrogen atom or a methyl group), R ¹ and R ³ are — (OC _n H _2n ) _m — (wherein n is an integer of 1 to 4). M represents 1 or 2, and an oxygen atom in the formula is bonded to X ¹ ), and R ² is a group represented by formula (IV),

式(Ｖ)

Formula (V)

又は式(VI)

Or formula (VI)

で表される２価の基である。）

It is a bivalent group represented by these. )

  Specific examples of the compound represented by formula (II) include norbornane dimethanol diacrylate, norbornane diethanol di (meth) acrylate, and diol diol obtained by adding 2 moles of ethylene oxide or propylene oxide to norbornane dimethanol. Di (meth) of diol obtained by adding 2 moles of ethylene oxide or propylene oxide to (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, tricyclodecane diethanol di (meth) acrylate, tricyclodecane dimethanol Acrylate, pentacyclopentadecane dimethanol di (meth) acrylate, pentacyclopentadecane diethanol di (meth) acrylate, pentacyclopentadecane dimethanol with ethylene oxide or propylene Di (meth) acrylate of diol obtained by adding 2 moles of oxide, and di (meth) acrylate of diol obtained by adding 2 moles of ethylene oxide or propylene oxide to pentacyclopentadecane diethanol. Candimethanol di (meth) acrylate and pentacyclopentadecanedimethanol di (meth) acrylate are preferred, and tricyclodecanedimethanol di (meth) acrylate is particularly preferred.

  In the same molecule used in the present invention, radically polymerizable unsaturated double bond and formula I

で表される３価の部分構造を有する化合物Ｂとしては、種々の構造の化合物を使用することができるが、中でも、式VIIで表される化合物を使用することが好ましい。

As the compound B having a trivalent partial structure represented by formula (1), compounds having various structures can be used. Among them, it is preferable to use a compound represented by formula VII.

（式中、Ｘ^１は前記式(III)で表される基であり、Ｘ^２は水素原子又は前記式(III)で表される基であり、Ｒ^１は-(OC_nH_2n)_m-（式中、ｎは１〜４の整数を表し、ｍは１又は２を表し、式中の酸素原子はＸ^１又はＸ^２と結合する。）で表される基である。）

(In the formula, X ¹ is a group represented by the formula (III), X ² is a hydrogen atom or a group represented by the formula (III), and R ¹ is — (OC _n H _2n ) _m. -(In the formula, n represents an integer of 1 to 4, m represents 1 or 2, and the oxygen atom in the formula is bonded to X ¹ or X ² ).)

  Specific examples of the compound represented by the formula (VII) include bis (2-acryloyloxyethyl) hydroxyethyl isocyanurate, bis (2-acryloyloxypropyl) hydroxypropyl isocyanurate, and bis (2-acryloyloxybutyl). ) Hydroxybutyl isocyanurate, bis (2-methacryloyloxyethyl) hydroxyethyl isocyanurate, bis (2-methacryloyloxypropyl) hydroxypropyl isocyanurate, bis (2-methacryloyloxybutyl) hydroxybutyl isocyanurate, tris (2-acryloyl) Oxyethyl) isocyanurate, tris (2-acryloyloxypropyl) isocyanurate, tris (2-acryloyloxybutyl) isocyanurate, tris (2-methac (Royloxyethyl) isocyanurate, tris (2-methacryloyloxypropyl) isocyanurate, tris (2-methacryloyloxybutyl) isocyanurate, among others, tris (2-acryloyloxyethyl) isocyanurate, tris (2-methacryloyl) Oxyethyl) isocyanurate is preferred, and tris (acryloyloxyethyl) isocyanurate is particularly preferred.

  Compound B has a rigid ring structure, and thus provides a high elastic modulus and a high glass transition temperature together with Compound A at a high temperature.

  Further, the compound C having 3 or more (meth) acryloyl groups and having a molecular weight of 250 or less per one (meth) acryloyl group used in the present invention is not particularly limited. A compound having a molecular weight per one (meth) acryloyl group of 200 or less is preferable, and a compound of 150 or less is more preferable.

  Further, the compound C is preferably a compound represented by the following formula VIII, formula IX or formula X.

（式中、Ｒ^１は-C₂H₄-、-C₃H₆-又は-C₄H₈-を表し、Ｒ^２は水素原子又はメチル基を表し、ｍは０又は１を表す。）

(In the formula, R ¹ represents —C ₂ H ₄ —, —C ₃ H ₆ — or —C ₄ H ₈ —, R ² represents a hydrogen atom or a methyl group, and m represents 0 or 1).

（式中、Ｒ^１は-C₂H₄-、-C₃H₆-又は-C₄H₈-を表し、Ｄは各々独立的に水素原子又は式III

(Wherein R ¹ represents —C ₂ H ₄ —, —C ₃ H ₆ — or —C ₄ H ₈ —, and each D independently represents a hydrogen atom or formula III

（式中、Ｚは水素原子又はメチル基を表す。）で表される基であるが、少なくとも３個は式IIIで表される基であり、ｍは０又は１を表す。）

(Wherein Z represents a hydrogen atom or a methyl group), at least three are groups represented by Formula III, and m represents 0 or 1. )

（式中、Ｒ^１は-C₂H₄-、-C₃H₆-又は-C₄H₈-を表し、Ｄは式III

Wherein R ¹ represents —C ₂ H ₄ —, —C ₃ H ₆ — or —C ₄ H ₈ —, and D represents formula III

（式中、Ｚは水素原子又はメチル基を表す。）で表される基であるが、少なくとも３個は式IIIで表される基であり、ｍは０又は１を表す。）

(Wherein Z represents a hydrogen atom or a methyl group), at least three are groups represented by Formula III, and m represents 0 or 1. )

  Examples of the compound represented by the above formula VIII, formula IX or formula X are shown below, and the molecular weight (M) of each compound and the molecular weight (Mfg) per (meth) acryloyl group in each compound are also described. In the above formula, m is preferably 0.

1. A compound in which R ¹ , R ² and m in the above formula VIII are as follows.
(A) A compound in which R ² is a hydrogen atom and m is 0 (M; 296 Mfg; 99)
(B) A compound in which R ¹ is —C ₂ H ₄ —, R ² is a hydrogen atom, and m is 1 (M; 428 Mfg; 143)
(C) A compound in which R ¹ is —C ₃ H ₆ —, R ² is a hydrogen atom, and m is 1 (M; 470 Mfg; 157)
(D) a compound in which R ¹ is —C ₄ H ₈ —, R ² is a hydrogen atom, and m is 1 (M; 512 Mfg; 171)
When R ² is —CH ₃ , the molecular weight (M) of each compound is increased by 52 and (Mfg) is increased by 14.

2. A compound in which R ¹ , D and m in the above formula IX are as follows.
(E) A compound in which three Ds are acryloyl groups, one D is a hydrogen atom, and m is 0 (M; 298 Mfg; 99)
(F) A compound in which R ¹ is —C ₂ H ₄ —, three D is an acryloyl group, one D is a hydrogen atom, and m is 1 (M; 474 Mfg; 158)
(G) A compound in which R ¹ is —C ₃ H ₆ —, three D are acryloyl groups, one D is a hydrogen atom, and m is 1 (M; 530 Mfg; 177)
(H) A compound in which R ¹ is —C ₄ H ₈ —, three D is an acryloyl group, one D is a hydrogen atom, and m is 1 (M; 586 Mfg; 195)
In (e) to (h), when D is a methacryloyl group, the molecular weight (M) of each compound increases by 52 and (Mfg) increases by 14.
(I) Compounds in which four Ds are acryloyl groups and m is 0 (M; 352 Mfg; 88)
(J) A compound in which R ¹ is —C ₂ H ₄ —, four D is an acryloyl group, and m is 1 (M; 528 Mfg; 132)
(K) A compound in which R ¹ is —C ₃ H ₆ —, four D is an acryloyl group, and m is 1 (M; 584 Mfg; 148)
(L) A compound in which R ¹ is —C ₄ H ₈ —, four D is an acryloyl group, and m is 1 (M; 640 Mfg; 162)
In (i) to (l), when D is a methacryloyl group, the molecular weight (M) of each compound increases by 66, and (Mfg) increases by 14.

3. A compound in which R ¹ , D and m in the above formula X are as follows.
(M) A compound in which three Ds are acryloyl groups, three Ds are hydrogen atoms, and m is 0 (M; 416 Mfg; 139)
(N) A compound in which R ¹ is —C ₂ H ₄ —, three D is an acryloyl group, three D is a hydrogen atom, and m is 1 (M; 680 Mfg; 227)
In (m) and (n), when D is a methacryloyl group, the molecular weight (M) of each compound increases by 52, and (Mfg) increases by 14.
(O) Compound in which 6 Ds are acryloyl groups and m is 0 (M; 578 Mfg; 96)
(P) a compound in which R ¹ is —C ₂ H ₄ —, 6 Ds are acryloyl groups, and m is 1 (M; 842 Mfg; 140)
In (o) and (p), when D is a methacryloyl group, the molecular weight (M) of each compound increases by 84 and (Mfg) increases by 14.

  Among these, (a), (b), (c), (e), (m) and (o) are more preferable because they can provide a high elastic modulus after curing, and (a), (b) , (E) and (o) are particularly preferred.

  In the ultraviolet curable composition for optical discs of the present invention, a radical polymerizable compound other than Compound A, Compound B and Compound C can be used. Specific examples include the following monofunctional and polyfunctional (meth) acrylates.

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, 2-hydroxyethyl (meth) acrylate, 3-chloro-2 -Hydroxypropyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, nonylphenoxyethyl (meth) acrylate, tetrahydrofurf Le (meth) acrylate, glycidyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, nonyl phenoxyethyl tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate.
Examples of the polyfunctional (meth) acrylate include 1,4-butanediol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate. , Neopentyl glycol di (meth) acrylate, 2-methyl-1,8-octanediol di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, ethylene glycol di (meth) Di (meth) acrylate of diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol, ethylene oxide modified phosphoric acid (meth) acrylate, ethylene Oxa Modified alkylated phosphoric acid (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyether (meth) acrylate, diethylaminoethyl (meth) acrylate, N-vinyl pyrrolidone, N-vinyl caprolactam, vinyl ether monomer and the like can be mentioned.

  The content ratio of Compound A and Compound B with respect to the whole radical polymerizable compound is 10% by mass or more, and the total content ratio of Compound A and Compound B is 40% by mass or more. Among them, the content ratio of Compound A and Compound B is preferably 20% by mass or more, and more preferably 30% by mass or more, respectively. Moreover, it is preferable that the total content rate of the compound A and the compound B is 50 mass% or more, and it is more preferable that it is 60 mass% or more. In such a range, a very rigid cured film can be obtained, and therefore extremely hard even at a high temperature and a high glass transition temperature can be obtained. Does not occur.

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

  Moreover, as an arbitrary component at the time of comprising the composition of this invention, there exist the following, It can use within the range which does not impair the effect of this invention. That is, as a sensitizer for a photopolymerization initiator, for example, trimethylamine, methyldimethanolamine, triethanolamine, p-dimethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N -Dimethylbenzylamine, 4,4'-bis (diethylamino) benzophenone, etc. Furthermore, amines that do not cause an addition reaction with the above-mentioned photopolymerizable compound can be used in combination. Of course, it is preferable to select and use those which are excellent in solubility in the ultraviolet curable compound and do not inhibit the ultraviolet transmittance. In addition, the ultraviolet curable resin composition of the present invention includes, as necessary, surfactants, leveling agents, thermal polymerization inhibitors, antioxidants such as hindered phenols and phosphites, hindered amines, and the like as necessary. Light stabilizers can also be used.

Next, the optical disk of the present invention will be described. An optical disk using the ultraviolet curable composition for an optical disk of the present invention,
Dye recording layer (a ₁ ), translucent light reflecting layer (t ₁ ), cured resin layer (c ₁ ) of the ultraviolet curable composition for optical disc of the present invention, dye recording layer (b), light reflecting It is an optical disc having a structure in which layers (r) are laminated in this order,
As a specific structure of such an optical disk, for example, there is an optical disk having the structure of FIG.

The optical disk of FIG. 1 includes a dye recording layer (a ₁ ) 2, a translucent light reflecting layer (t ₁ ) 3, and a cured resin layer (c ₁ ) 4 of an ultraviolet curable composition on a substrate (d ₁ ) 1. And a dye recording layer (b) 5, a light reflection layer (r) 6, and a substrate (d ₂ ) 7 in this order. In FIG. 1, the dye recording layer (a ₁ ) 2 and the translucent light reflecting layer (t ₁ ) 3 form the first recording layer 21, and the dye recording layer (b) 5 and the light reflecting layer (r) 6 Forms the second recording layer 22. Further, the translucent light reflecting layer (t ₁ ) 3 and the dye recording layer (b) 5 are laminated via a cured resin layer (c ₁ ) 4 of an ultraviolet curable composition so as to face each other. In FIG. 1, a convex recording track (groove) 11 (first recording layer) and a convex recording track (groove) 12 (second recording layer) are also illustrated in the light incident direction.

In the optical disk of the present invention, an adhesive layer 8 may be provided between the light reflecting layer (r) 6 and the substrate (d ₂ ) 7 (FIG. 2). Further, between the cured resin layer (c ₁ ) 4 and the dye recording layer (b) 5, the dye recording layer (a ₂ ) 31, the translucent light reflecting layer (t ₂ ) 32, and the ultraviolet curable type. An optical disc having a structure in which one or two or more laminates (s) 23 in which the cured resin layer (c ₂ ) 33 of the composition is laminated in this order may be used.
In this case, lamination is performed so that the cured resin layer (c ₁ ) 4 and the dye recording layer (a ₂ ) 31 are in contact with each other, and the dye recording layer (b) 5 and the cured resin layer (c ₂ ) 33 are in contact with each other. The cured resin layer (c ₂ ) 33 is formed from the above-described ultraviolet curable composition that has been described in detail so far.
Further, in the case of laminating two or more laminate (s) 23 is, the dye recording layer of one laminate (s ₁₎ and (a _2), other laminate and the adjacent laminated body (s ₁₎ (s ₂₎ curing the resin layer (c ₂₎ and is laminated with the cured resin layer so far above ultraviolet curable composition has been described in detail so as to contact the.
An example in which one layer of the laminate (s) 23 is further laminated on the first recording layer 21 in the optical disk shown in FIG. 2 is the optical disk in FIG.

  The optical disc of the present invention can be manufactured, for example, by the following steps.

  A method for manufacturing the optical disk shown in FIG. 1 will be described below.

First, a substrate (d ₁ ) 1 having a guide groove for tracking a laser beam called a recording track (groove) 11 is manufactured by injection molding polycarbonate resin. Next, after the azo dye is dissolved in a solvent, the dye recording layer (a ₁ ) 2 is formed on the surface of the substrate (d ₁ ) 1 on the recording track side by spin coating or the like. Further, a semi-transparent light reflection layer (t ₁ ) 3 is formed thereon by sputtering or vapor deposition of a silver alloy or the like, and the first recording layer 21 is produced.

Next, the substrate (d ₂ ) 7 having guide grooves for tracking the laser light called recording tracks (grooves) 12 is produced by injection molding of polycarbonate resin. Next, a light reflecting layer (r) 6 is formed by sputtering or vapor-depositing a silver alloy or the like. On this, an azo dye is dissolved in a solvent, and then a dye recording layer (b) 5 is formed on the surface of the substrate (d ₂ ) 7 on the recording track side by spin coating or the like to produce a second recording layer 22. To do.

An ultraviolet curable composition is applied to the surface of the translucent light reflecting layer (t ₁ ) 3 of the substrate (d ₁ ) having the first recording layer, and the dye recording layer (b) 5 of the substrate having the second recording layer. 1 is applied by spin coating or the like, and ultraviolet rays are irradiated from one or both sides of the bonded discs to cure the ultraviolet curable composition to form a cured resin layer (c ₁ ) 4. Make it.

  A method for manufacturing the optical disk shown in FIG. 2 will be described below.

First, a substrate (d ₁ ) 1 having a guide groove for tracking a laser beam called a recording track (groove) 11 is manufactured by injection molding polycarbonate resin. Next, after the azo dye is dissolved in a solvent, the dye recording layer (a ₁ ) 2 is formed on the surface of the substrate (d ₁ ) 1 on the recording track side by spin coating or the like. Further, a semi-transparent light reflection layer (t ₁ ) 3 is formed thereon by sputtering or vapor deposition of a silver alloy or the like, and the first recording layer 21 is produced.

On this, a cured resin layer (c ₁ ) 4 of the ultraviolet curable composition for an optical disk of the present invention is formed. At that time, a recording track (groove) 13 is transferred onto the surface using a mold. The process of transferring the recording track (groove) 13 is as follows. A mold for forming a recording track (groove) 13 on a semi-transparent light reflecting layer (t ₁ ) 3 of a substrate (d ₁ ) 1 by applying the ultraviolet curable composition for optical disk of the present invention. The composition of the present invention is cured by applying ultraviolet rays from one or both sides of the bonded disc. Thereafter, the mold is peeled off to prepare an optical disk substrate in which the cured resin layer (c ₁ ) 4 is provided with a recording track (groove) 13. The mold can be used without particular limitation as long as it has sufficient peelability with respect to the cured resin layer (c ₁ ) 4, but a resin stamper is preferable in terms of productivity and cost. As the material of the resin stamper, for example, an acrylic resin, a methacrylic resin, a polycarbonate resin, a polyolefin resin (particularly amorphous polyolefin), a polyester resin, a polystyrene resin, an epoxy resin, or the like is used. it can. Since it is desired that the adhesive property with the cured resin layer (c ₁ ) 4 of the ultraviolet curable composition for optical discs of the present invention is low and the releasability is high, polyolefin resins are preferred.

Subsequently, an azo dye is dissolved in a solvent on the surface of the optical disc substrate on the side having the recording track (groove) 13 of the cured resin layer (c ₁ ) 4, and then the dye recording layer (b) by spin coating or the like. 5 is formed. Further, the light recording layer (r) 6 is formed by sputtering or vapor deposition of silver alloy or the like, and the second recording layer 22 is manufactured.

Next, a substrate (d ₂ ) 7 having no recording layer is produced by injection molding of a polycarbonate resin. An ultraviolet curable adhesive is applied to the surface of the light reflecting layer (r) 6 of the substrate having the two recording layers obtained as described above, and is bonded to the substrate (d ₂ ) 7, and this bonding is performed. The optical disk shown in FIG. 2 can be produced by irradiating ultraviolet light from one or both sides of the disc to cure the ultraviolet curable adhesive and form the adhesive layer 8.

  A method for manufacturing the optical disk shown in FIG. 3 will be described below.

Similar to the method of forming the first recording layer 21 and the cured resin layer (c ₁ ) 4 in the optical disc shown in FIG. 2, the first recording layer 21 is formed on the substrate (d ₁ ) 1 shown in FIG. Then, a cured resin layer (c ₁ ) 4 of an ultraviolet curable composition having a recording track (groove) is formed thereon. Next, in the same manner as the method for forming the first recording layer 21 in the optical disc shown in FIG. 2, the laminate (s) 23 shown in FIG. 3 is formed. On this, the 2nd recording layer 22 is formed like the method of forming the 2nd recording layer 22 in the optical disk shown in FIG. Finally, an ultraviolet curable adhesive is applied to the surface of the light reflecting layer (r) 6 of the second recording layer 22 and bonded to a polycarbonate resin substrate (d ₂ ) 7 having no recording layer. The optical disk shown in FIG. 3 can be produced by irradiating ultraviolet rays from one side or both sides of the substrate to cure the ultraviolet curable adhesive to form the adhesive layer 8.

  As the organic dye used in the recording layer, in addition to the azo dye, any organic dye that can form pits by laser light used for recording can be used without particular limitation, for example, cyanine-based, phthalocyanine-based, naphthalocyanine-based, Anthraquinone, triphenylmethane, pyrylium or thiapyrylium salts, squarylium, croconium, formazan, metal complex dyes and the like can be mentioned. 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. As the recording layer material, a phase change recording material can be used in place of the organic dye, and a chalcogen alloy can be used as the material, and examples thereof include GeSbTe and AgInSbTe.

The materials used for the first recording layer 21 and the second recording layer 22 may be the same or different. Further, the material used for the dye recording layer (a ₂ ) of the laminate (s) may be the same as or different from the material used for the other dye recording layers.
Furthermore, the translucent light reflecting layer and the light reflecting layer can be used without particular limitation as long as they can reflect and record / reproduce laser light in addition to the silver alloy, such as gold, copper, and aluminum. Examples thereof include inorganic compounds such as metals and alloys thereof, and silicon. The translucent light reflecting layer and the light reflecting layer can be obtained by forming a thin film by a method such as sputtering or vapor deposition using these materials.

The translucent light reflecting layer is a light reflecting layer having an appropriate light transmittance to such an extent that recording and reproduction of the second recording layer are possible. Specifically, it is preferably a reflective layer having a light transmittance of 40% or more for recording and reproducing information and an appropriate light reflectance (usually 30% or more). The thickness of the translucent light reflecting layer is usually preferably 50 nm or less. More preferably, it is 30 nm or less. More preferably, it is 25 nm or less.
The light reflecting layer of the second recording layer needs to have a high reflectance. Moreover, it is desirable that it is highly durable. In order to ensure a high reflectance, the thickness of the light reflecting layer is usually preferably 20 nm or more. More preferably, it is 30 nm or more. More preferably, it is 50 nm or more. However, in order to shorten the production tact time and reduce the cost, it is preferable to be thin to some extent, and is usually 400 nm or less. More preferably, it is set to 300 nm or less.

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. The gel fraction of the cured product is preferably 70% to 100%, more preferably 85% to 100%. In addition, as a board | substrate used for the optical disk of this invention, what is normally used as a board | substrate for optical disks can be used, and especially a polycarbonate substrate can be used suitably.
As thickness of a board | substrate, 0.1-2.0 mm is preferable and 0.3-1.5 mm or more is more preferable.

  The ultraviolet curable composition for an optical disk of the present invention is not limited to the use of write-once DVD-R and DVD + R, but is a rewritable DVD-RW, DVD + RW, DVD-RAM or other DVD, or on an optical disk substrate. In addition, an optical disc in which a light transmission layer is formed by laminating a cured film of an ultraviolet curable composition, for example, a next generation type optical disc using a blue-violet laser beam as a laser beam for reading and writing information (trade name “Blu- ray "manufactured by Sony, trade name" HD-DVD ") and the like.

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

(Example 1 and Comparative Example 1)
<Preparation of composition and optical disc sample>
According to the blending composition shown in Table 1 below, each composition material was heated and dissolved at 60 ° C. for 3 hours to prepare UV curable compositions of Examples and Comparative Examples.
Next, the optical disk of FIG. 2 was produced by the method described above. First, a substrate (d ₁ ) 1 having a guide groove for tracking a laser beam called a recording track (groove) was produced by injection molding a polycarbonate resin. Next, after the azo dye was dissolved in a solvent, the dye recording layer (a ₁ ) 2 was formed on the surface of the substrate (d ₁ ) 1 on the recording track side by spin coating. Further thereon, a semi-transparent light reflecting layer (t ₁ ) 3 was formed by sputtering a silver alloy, whereby a first recording layer 21 was produced.

On the translucent light reflecting layer (t ₁ ) 3 of the substrate (d ₁ ) 1, the UV curable composition for each of the above examples and each comparative example is applied and bonded to a resin stamper. The ultraviolet curable composition was cured by irradiating ultraviolet rays from the resin stamper side of the combined disks. Thereafter, the resin stamper was peeled off to form a cured resin layer (c ₁ ) 4 having a film thickness of about 55 μm onto which the recording track (groove) was transferred. Here, the resin stamper was produced by injection molding a polyolefin-based resin. Subsequently, after the azo dye is dissolved in a solvent on the surface of the cured resin layer (c ₁ ) 4 of the optical disk substrate having the recording track (groove), the dye recording layer (b) 5 is formed by spin coating. Formed. Further, the light recording layer (r) 6 was formed by sputtering a silver alloy, and the second recording layer 22 was produced.

Next, a substrate (d ₂ ) 7 having no recording layer is produced by injection molding of a polycarbonate resin. On the surface of the light reflecting layer (r) 6 of the substrate having the two recording layers obtained as described above, an ultraviolet curable adhesive Dicure Clear SD-694 (manufactured by Dainippon Ink & Chemicals, Inc.) Is applied to the substrate (d ₂ ) 7, and ultraviolet rays are irradiated from the surface of the substrate (d ₂ ) 7 of the bonded disc to cure the ultraviolet curable adhesive, thereby forming the adhesive layer 8. The optical disk of FIG. 2 was produced.

(Measurement of jitter and Push-Pull signal)
The jitter of the reproduction signal mark length and the Push-Pull signal in the dye recording marks of the optical discs of each of the produced examples and comparative examples were measured. In order to measure the jitter, recording was performed using an evaluation machine (DDU-1000 manufactured by Pulstec Corp., maximum recording power 15 mW) equipped with a semiconductor laser having a wavelength of 657 nm (NA = 0.65) in the second recording layer of each optical disk. A linear velocity density of 9.1 m / s, an EFM + signal of 8-16 modulation, a mark having a mark length of 3T to 14T at a recording power where the asymmetry of the recording signal is close to 0 (here, the modulation is 0.6 or more). Recorded. Thereafter, the recorded signal was reproduced with a reproduction linear velocity density of 3.8 m / s and a reproduction power of 0.7 mW, and an average value of jitter (signal deviation) of the reproduction signal of the mark having a mark length of 3T to 14T was measured. Tables 1 to 3 show the optical disks of the examples and comparative examples and the evaluation results. If the jitter is 8% or less, the recording characteristics are good, and the push-pull signal is better as the numerical value is larger.

The abbreviations in Tables 1 and 2 represent the following compounds.
-TCDDA: Tricyclodecane dimethanol diacrylate-TAEIC: Tris (acryloyloxyethyl) isocyanurate-TMPTA: Trimethylolpropane triacrylate-TMP (3EO) TA: Add 3 mol of ethylene oxide to 1 mol of trimethylolpropane Triacrylate of the triol obtained above (compound of the above (b) (R ¹ in formula VIII is —C ₂ H ₄ —, R ² is a hydrogen atom, m is 1 (M; 428 Mfg ; 143))
TMP (15EO) TA: Triacrylate of triol obtained by adding 15 mol of ethylene oxide to 1 mol of trimethylolpropane (M; 956 Mfg; 319)
DP (6EO) TA: triacrylate of hexaalcohol obtained by adding 6 mol of ethylene oxide to 1 mol of dipentaerythritol (M; 680 Mfg; 227)
UA-1: urethane acrylate obtained by reacting polytetramethylene glycol (molecular weight 850), tolylene diisocyanate and hydroxyethyl acrylate at a molar ratio of 1/2/2. HCPK: 1-hydroxycyclohexyl phenyl ketone. TPO: trimethylphenyl Diphenylphosphine oxide ・ MPTMS: Mercaptopropyltrimethoxysilane ・ EPTMS: Epoxypropyltrimethoxysilane

≪Summary of evaluation results≫
As is apparent from Table 1 above, when the ultraviolet curable compositions obtained in Examples 1 to 7 according to the present invention were used, the jitter of the second recording layer was 8% or less, indicating excellent results. Push-Pull was also a sufficiently large result. Furthermore, Examples 1 to 6 using Compound C having a molecular weight of 150 or less per acryloyl group are Examples 7 using Compound C having a molecular weight of more than 150 and 250 or less per acryloyl group. Compared to the above, good jitter and Push-Pull were obtained.
On the other hand, Comparative Example 1 is only Compound A and Compound C and does not contain Compound B, and Comparative Example 2 is only Compound B and Compound C and does not contain Compound A. As a result, Comparative Example 1 Jitter could not be measured for both 1 and 2, Push-Pull was very low, and the characteristics as an optical disk were insufficient. In Comparative Example 3, a compound having a molecular weight of more than 250 per acryloyl group was used in place of Compound C. As a result, both jitter and Push-Pull were insufficient.

It is a figure which shows an example of the optical disk of this invention. It is a figure which shows an example of the optical disk of this invention. It is a figure which shows an example of the optical disk of this invention.

Explanation of symbols

1 Substrate (d ₁ )
2 Dye recording layer (a ₁ )
3 Translucent light reflecting layer (t ₁ )
4 Cured resin layer of UV curable composition (c ₁ )
5 Dye recording layer (b)
6 Light reflection layer (r)
7 Substrate (d ₂ )
8 Adhesive layer 11 Convex recording track (groove)
12 Convex recording track (groove)
13 Convex recording track (groove)
21 A _first recording layer in which a dye recording layer (a ₁ ) 2 and a translucent light reflecting layer (t ₁ ) 3 are laminated 22 A dye recording layer (b) 5 and a light reflecting layer (r) 6 are laminated Second recording layer 23 Laminate (s)
31 Dye recording layer (a ₂ )
32 Translucent light reflecting layer (t ₂ )
33 Cured resin layer of ultraviolet curable composition (c ₂ )

Claims (9)

An ultraviolet curable composition for optical discs containing a radical polymerizable compound,
(1) Compound A having a radical polymerizable unsaturated double bond and a polycyclic structure in the same molecule,
(2) Radical polymerizable unsaturated double bond and formula I in the same molecule

And (3) a compound C having 3 or more (meth) acryloyl groups and a molecular weight of 250 or less per (meth) acryloyl group
An ultraviolet curable composition for optical discs, comprising: Compound A is represented by Formula II
^{X 1 -R 1 -O-R 2} -O-R 3 -X 1 (II)
(Wherein X ¹ represents the formula (III)

(Wherein Z represents a hydrogen atom or a methyl group), R ¹ and R ³ are — (OC _n H _2n ) _m — (wherein n is an integer of 1 to 4). M represents 1 or 2, and an oxygen atom in the formula is bonded to X ¹ ), and R ² is a group represented by formula (IV),

Formula (V)

Or formula (VI)

It is a bivalent group represented by these. The ultraviolet curable composition for optical discs of Claim 1 which is a compound represented by this. Compound B is of formula VII

(In the formula, X ¹ is a group represented by the formula (III), X ² is a hydrogen atom or a group represented by the formula (III), and R ¹ is — (OC _n H _2n ) _m. -(Wherein n represents an integer of 1 to 4, m represents 1 or 2, and the oxygen atom in the formula is bonded to X ¹ or X ² ). The ultraviolet curable composition for optical discs according to claim 1, which is a compound to be produced. 4. The optical disk according to claim 1, wherein the compound C is a compound having 3 or more (meth) acryloyl groups and having a molecular weight of 150 or less per (meth) acryloyl group. UV curable composition. Compound C is Formula VIII,

(In the formula, R ¹ represents —C ₂ H ₄ —, —C ₃ H ₆ — or —C ₄ H ₈ —, R ² represents a hydrogen atom or a methyl group, and m represents 0 or 1).
Formula IX,

(Wherein R ¹ represents —C ₂ H ₄ —, —C ₃ H ₆ — or —C ₄ H ₈ —, and each D independently represents a hydrogen atom or formula III

(Wherein Z represents a hydrogen atom or a methyl group), at least three are groups represented by Formula III, and m represents 0 or 1. )
Or X

Wherein R ¹ represents —C ₂ H ₄ —, —C ₃ H ₆ — or —C ₄ H ₈ —, and D represents formula III

(Wherein Z represents a hydrogen atom or a methyl group), at least three are groups represented by Formula III, and m represents 0 or 1. The ultraviolet curable composition for optical discs according to any one of claims 1, 2, and 3. A dye recording layer (a ₁ ), a translucent light reflecting layer (t ₁ ), and a cured resin layer (c) of the ultraviolet curable composition for optical discs according to any one of claims 1, 2, 3, 4 or 5. ₁ ) An optical disc having a structure in which a dye recording layer (b) and a light reflection layer (r) are laminated in this order. Further, a dye recording layer (a ₂ ), a translucent light reflecting layer (t ₂ ), and a cured resin layer of the ultraviolet curable composition for optical discs according to any one of claims 1, 2, 3, 4 or 5. (c ₂ ) and one or more laminates (s) laminated in this order,
Between the cured resin layer (c ₁ ) and the dye recording layer (b),
The cured resin layer (c ₁ ) and the dye recording layer (a ₂ ) are in contact, the dye recording layer (b) and the cured resin layer (c ₂ ) are in contact, and two or more laminates ( when stacking s) of the dye recording layer of one laminate (s ₁₎ and (a _2), the cured resin of the laminate (s ₁₎ and another adjacent stack (s ₂₎ 7. The optical disk according to claim 6, wherein the optical disk is laminated so as to be in contact with the layer (c ₂ ). The optical disk according to claim 6 or 7, wherein the dye recording layer (a ₁ ) is provided on the substrate (d ₁ ), and the light reflecting layer (r) is provided on the substrate (d ₂ ). The optical disc according to claim 8, further comprising an adhesive layer between the light reflecting layer (r) and the substrate (d ₂ ).

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