JP2002037855A - Photocurable resin composition for photorecording disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material excellent in transparency which does not absorpe light in a wavelength range of 380-800 nm and has a excellent molding property and functions as an adhesive agent which adheres a transparent substrate on the both faces in a multilayer disk. SOLUTION: The multilayer photorecording disk, is provided to solve the problem by using photocurable resin composition having (A) a cation polymerizable monomer, (B) a cation polymerizable copolymer whose glass transition point is 20 deg.C or less and (C) a photoinitiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable resin composition having a function of an adhesive for forming a recording layer and bonding substrates on both sides in a multilayer optical recording disc having at least two recording layers. About.

[0002]

2. Description of the Related Art In recent years, DVDs (digital video discs or digital versatile discs) capable of recording a large amount of information among optical recording media have been replaced by CDs.
It is a recording medium that can replace (compact disc). The current DVD has a structure in which two discs are bonded together, and a hot-melt adhesive, a radical-based or a cationic light-curable adhesive is used as the adhesive, and only functions as an adhesive. Met.

Recently, DVDs having two to five recording layers have been proposed to increase the recording capacity. This D
VD requires a resin having excellent moldability for forming a recording layer and an excellent transparency functioning as an adhesive for bonding a double-sided substrate, such as a hot melt resin, a radical UV type resin,
Cationic UV-type resins have been proposed. Hot melt resin is suitable for moldability of the recording layer because it is a thermoplastic resin, and satisfies the requirements for transparency.However, deformation of the substrate due to heat applied during coating and molding, dimensional stability at high temperatures And there is a problem in adhesion. The radical-type photocurable resin is not suitable for moldability of the recording layer because the cured film is hard, in addition to the problem that sufficient adhesive strength cannot be obtained due to a large curing shrinkage. Further, transparency is not sufficient. Cationic photocurable resins have low curing shrinkage and can be expected to have adhesive strength, but are not suitable for moldability of the recording layer because of the rigidity of the cured film, similar to radical photocurable resins, and have sufficient transparency. Not.

[0004]

SUMMARY OF THE INVENTION The present invention provides two layers to five layers.
Optical recording disk having a recording layer having two layers has a moldability for forming the recording layer and a function as an adhesive for bonding a double-sided substrate, and has no absorption in a wavelength range of 380 to 800 nm. A curable resin composition is provided.

[0005]

Means for Solving the Problems The present inventors have conducted various studies in order to solve the above-mentioned problems, and as a result, have a moldability for forming a recording layer and a function as an adhesive for bonding a double-sided substrate. A photocurable resin composition having no absorption in the wavelength range of 380 to 800 nm was found.

That is, the present invention provides the following (1) to (7)
Is provided. (1) A resin composition for forming a recording layer of a multilayer optical recording disk comprising two or more layers, wherein (A) a cationically polymerizable monomer, and (B) a cation having a glass transition temperature (Tg) of 20 ° C. or lower. A photocurable resin composition for an optical disc, comprising a polymerizable copolymer and (C) a photoinitiator. (2) The photocurable resin composition for an optical recording disk according to (1), wherein the (A) cationic polymerizable monomer is a compound or a mixture having an oxetane ring and / or an oxirane ring in a molecule. (3) (A) The compound having an oxirane ring in the cationically polymerizable monomer is at least one compound selected from bisphenol-type glycidyl ether, alicyclic epoxy compound, and aliphatic glycidyl ether. The photocurable resin composition for an optical recording disk according to (2). (4) (B) the cationically polymerizable copolymer is oxetanyl (meth) acrylate and / or glycidyl (meth)
The photocurable resin composition for optical recording disks according to (1), which is an acrylic copolymer containing acrylate. (5) The photocurable resin composition for an optical recording disk according to any one of (1) to (4), wherein the photoinitiator (C) is an onium salt. (6) The content of the resin composition is (A) 30 to 69.7% by mass of a cationically polymerizable monomer, (B) 63 to 30% by mass of a cationically polymerizable copolymer, and (C) a photoinitiator of 7 to 0. The photocurable resin composition for an optical disc according to any one of (1) to (5), wherein the composition is: 3% by mass. (7) An optical recording disk obtained by using the photocurable resin composition according to any one of (1) to (6).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a resin composition for forming a recording layer of a multilayer optical recording disk comprising two or more layers according to the present invention will be described. [Photocurable Resin Composition for Optical Disc] The photocurable resin composition of the present invention comprises (A) a cationically polymerizable monomer, (B) a cationically polymerizable copolymer, and (C) a photoinitiator. is there.

The cationic polymerizable monomer (A) used in the present invention is not particularly limited, but is preferably a compound or a mixture having an oxetane ring and / or an oxirane ring in the molecule. The amount of the compound having an oxetane ring to be used is preferably 5 to 80% by mass of (A) the cationically polymerizable monomer, and is preferably 10 to 5% by mass.
0 mass% is more preferred. By setting the amount to be 5% by mass or more, the curability is improved and curing can be performed in a short time. When the amount is 80% by mass or less, the adhesion at high temperatures is improved. The amount of the compound having an oxirane ring is preferably 20 to 95% by mass, more preferably 30 to 85% by mass. When the amount is 20% by mass or more, the adhesiveness at a high temperature is improved, and when the amount is 95% by mass or less, the curability is improved, and the curing can be performed in a short time.

The amount of the cationic polymerizable monomer (A) used in the resin composition is preferably 30 to 69.7% by mass. When the amount is 30% by mass or more, the curability is increased. When the amount is 69.7% by mass or less, the resin viscosity is reduced and the coating suitability is improved.

Hereinafter, (A) the cationically polymerizable monomer will be described in detail. <Polymerizable monomer having an oxetane ring> The polymerizable monomer having an oxetane ring used in the present invention has 1 to 5 oxetane rings in the molecule and has no absorption in a wavelength region of 380 to 800 nm. It is not particularly limited as long as it is a compound.

Specific examples of the polymerizable monomer having one oxetane ring include 3-ethyl-3-hydroxymethyloxetane, 3- (meth) allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanyl) Methoxy) methylbenzene, 4-fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene,
4-methoxy- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, [1- (3-ethyl-3
-Oxetanylmethoxy) ethyl] phenyl ether,
Isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl-3-oxetanylmethyl) ether, 2
-Ethylhexyl (3-ethyl-3-oxetanylmethyl) ether, ethyldiethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl (3 -Ethyl-
3-oxetanylmethyl) ether, dicyclopentenylethyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromophenyl (3
-Ethyl-3-oxetanylmethyl) ether, 2-tetrabromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether, tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tribromophenoxyethyl ( 3-ethyl-3-oxetanylmethyl) ether, 2-hydroxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl (3-ethyl-3-oxetanylmethyl) ether, butoxyethyl (3-ethyl- 3-oxetanylmethyl) ether, pentachlorophenyl (3-ethyl-3-oxetanylmethyl) ether, pentabromophenyl (3-ethyl-3-oxetanylmethyl) ether, bornyl (3-ethyl-3-oxetanylmethyl)
Ether and the like.

Specific examples of the polymerizable monomer having two oxetane rings include 1,4-bis {[(3-ethyl-3
-Oxetanyl) methoxy] methyl} benzene, bis {[(1-ethyl) 3-oxetanyl] methyl} ether, 1,4-bis [(3-ethyl-3-oxetanyl)
Methoxy] benzene, 1,3-bis [(3-ethyl-3
-Oxetanyl) methoxy] benzene, 3,7-bis (3-oxetanyl) -5-oxa-nonane, 1,4-
Bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, 1,2-bis [(3-ethyl-3-oxetanyl) Methoxy) methyl
Propane, ethylene glycol bis (3-ethyl-3-
Oxetanylmethyl) ether, dicyclopentenylbis (3-ethyl-3-oxetanylmethyl) ether,
Triethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether,
Tricyclodecanediyl dimethylenebis (3-ethyl-
3-oxetanylmethyl) ether, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl]
Butane, 1,6-bis [(3-ethyl-3-oxetanylmethoxy) methyl] hexane, polyethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol A bis (3-ethyl-3-
Oxetanylmethyl) ether, PO-modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, EO-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, PO-modified hydrogenated bisphenol Abis (3 -Ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol F bis (3-
Ethyl-3-oxetanylmethyl) ether and the like.

Specific examples of the polymerizable monomer having 3 to 5 oxetane rings include trimethylolpropane tris (3-ethyl-3-oxetanylmethyl) ether,
Pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol pentakis (3-ethyl-)
3-oxetanylmethyl) ether and the like.

<Polymerizable monomer having oxirane ring>
The polymerizable monomer having an oxirane ring used in the present invention is not particularly limited as long as it is a compound having 1 to 4 oxirane rings in the molecule. The polymerizable monomer will be described with a specific example. 1 epoxy group
Phenyl glycidyl ether,
There are butyl glycidyl ether and the like, and examples of the compound having two or more epoxy groups include hexanediol diglycidyl ether, tetraethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, and bisphenol A diglycidyl ether. 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate;
Alicyclic epoxies such as bis- (3,4-epoxycyclohexyl) adipate are also included. These cationically polymerizable monomers may be used alone or in combination of two or more.

<Cationically polymerizable copolymer> Next, (B) the cationically polymerizable copolymer will be described in detail. The (B) cationically polymerizable copolymer used in the present invention is not particularly limited as long as the glass transition temperature (Tg) is 20 ° C. or lower, but is not limited to using an acrylic monomer having an oxetane ring and an oxirane ring. It is preferable to use an acrylic copolymer such as oxetanyl (meth) acrylate and / or glycidyl (meth) acrylate in which a cationic polymer group is introduced into the polymer. Other copolymerizable copolymers are copolymerizable with these monomers,
The monomer is not particularly limited as long as it is a highly transparent monomer having no absorption in a wavelength range of 380 to 800 nm. Specific examples include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (acrylate), 2-ethylhexyl (meth) acrylate, amyl (meth) acrylate, hexadecyl (meth) acrylate, and octadecyl ( Examples thereof include (meth) acrylate, butoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. These can be used alone or in combination of two or more. (B) The content of oxetanyl (meth) acrylate and glycidyl (meth) acrylate in the cationically polymerizable copolymer is preferably from 10% by mass to 50% by mass. When the content is 10% by mass or more, sufficient adhesive strength is obtained, and when the content is 50% by mass or less, the cured coating film has sufficient flexibility, and the removability of the stamper is good.

Although the method for synthesizing the copolymer is not particularly limited,
Usually, synthesis is performed by known radical solution polymerization.
(B) The glass transition temperature (hereinafter, Tg) of the cationically polymerizable copolymer may be 20 ° C. or lower, preferably 0 ° C.
It is below ° C. When Tg is 20 ° C. or less, highly accurate pattern transferability can be obtained when the recording layer is hot-pressed with a stamper. The molecular weight of this cationically polymerizable copolymer is preferably from 2,000 to 20,000 in terms of polystyrene equivalent number average molecular weight measured by gel permeation chromatography (GPC). More preferably, it is 4000 to 15000. When the number average molecular weight is 2,000 to 20,000, good coating properties can be obtained.

The amount of the cationically polymerizable copolymer used in the resin composition is preferably from 30 to 63% by mass. When the used amount is 30% by mass to 63% by mass, coating suitability is improved.

<(C) Photoinitiator> The (C) photoinitiator of the present invention, which will be described in detail below, is used for the cationic polymerization of the components (A) and (B) by light. There is no particular limitation as long as it is a starting compound, and any compound can be used. Preferred examples of the photocationic initiator include onium salts. This onium salt is a compound that reacts with light and releases a Lewis acid. Specifically, it is represented by the following general formula (1).

[R ¹ _a R ² _b R ³ _c R ⁴ _d W] ^{m +} [MX _{n + m} ] ^m− (1) (where the cation is an onium ion, and W is S,
Se, Te, P, As, Sb, Bi, O, I, Br, C
1 or N≡N. R ¹ , R ² , R ³ , and R ⁴ are the same or different organic groups, a, b, c, and d are each an integer of 0 to 3, and (a + b + c + d) is equal to the valence of W. M is a halogenated complex [MX _{n + m} ]
Metal or metalloid constituting the central atom of, for example, B, P, As, Sb, Fe, Sn, Bi, Al,
Ca, In, Ti, Zn, Sc, V, Cr, Mn, Co
And so on. X is, for example, a halogen atom such as F, Cl, or Br; m is the net charge of the halide complex ion; and n is the valence of M. )

In the general formula (1), specific examples of the onium ion include diphenyliodonium, 4-methoxydiphenyliodonium, bis (4-methylphenyl)
Iodonium, bis (4-tert-butylphenyl)
Iodonium, bis (dodecylphenyl) iodonium, triphenylsulfonium, diphenyl-4-thiophenoxyphenylsulfonium, bis [4- (diphenylsulfonio) -phenyl] sulfide, bis [4
- (di (4- (2-hydroxyethyl) phenyl) sulfonio) - phenyl] sulfide, eta ^{5-2,4-(cyclopentadienyl)} [1,2,3,4,5,6-.eta.
(Methylethyl) benzene] -iron (1+).

In the general formula (1), specific examples of the anion include tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate and the like.

These photocationic initiators can be used alone or in combination of two or more. The content ratio of the component (C) in the resin composition of the present invention is preferably from 0.3 to 7% by mass, and more preferably from 0.3 to 3% by mass. When the content of the component (C) is 0.3% by mass or more, the curing state of the resin composition becomes better, and when the content is 7% by mass or less, the elution of the initiator during the curing process and after curing can be reduced. it can.

Further, other additives can be used in the composition of the present invention, if necessary. <Other resin components> Examples of other resin components include polyamide, polyamideimide, polyurethane, polybutadiene, polychloroprene, polyether, polyester, styrene-butadiene-styrene block copolymer, petroleum resin, xylene resin, and ketone resin. , Cellulose resin, fluorine-based oligomer, silicon-based oligomer, polysulfide-based oligomer, and the like. They are,
One kind may be used alone, or two or more kinds may be used in combination.

<Modifier> Examples of the modifier include a polymerization initiator, an antioxidant, a leveling agent, a wettability improver,
Examples include an adhesion promoter, a surfactant, a plasticizer, and an ultraviolet absorber. These may be used alone or in combination of two or more.

<Diluent> The diluent can be used for imparting coatability or improving the coatability. As a diluent, an organic solvent is usually used. The physical properties of the organic solvent are not particularly limited, but a compound or a mixture having a boiling point of 200 ° C. or lower at 1 atm is preferable, a boiling point of 150 ° C. or lower is more preferable, and a temperature of 70 ° C. to 130 ° C. is more preferable.

These diluents can be used alone or in combination of two or more. The amount of the diluent is not particularly limited, and the amount is selected according to the suitability for application.

These include alcohols, glycol ethers, ethylene glycol ether acetates, aromatic hydrocarbons, ketones, esters, ethers and the like. Specific examples of these compounds include the following.

Examples of alcohols include methanol,
Ethanol, propanol, butanol and the like can be mentioned. Examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, 3-methoxybutanol, 3-methyl-3-methoxybutanol, and the like.

Examples of the ethylene glycol ether acetates include ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, and ethyl ethoxypro Piolate and the like.

Examples of the aromatic hydrocarbons include toluene, xylene and the like. Ketones include methyl ethyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone and the like.

As esters, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, 2-hydroxy-2-
Methyl methyl propionate, ethyl 2-hydroxy-2-methylpropionate, methyl hydroxyacetate, ethyl hydroxyacetate, butyl hydroxyacetate, methyl lactate,
Ethyl lactate, butyl lactate, methyl 3-hydroxypropionate, ethyl 3-hydroxypropionate, propyl 3-hydroxypropionate, butyl 3-hydroxypropionate, propyl 2-hydroxy-3-methylbutanoate, methyl methoxyacetate, methoxyacetic acid Ethyl, propyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate, propyl ethoxyacetate,
Butyl ethoxyacetate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, butyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, 2-ethoxypropion Propyl acetate, butyl 2-ethoxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate,
Propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl 3-ethoxypropionate, 3
-Ethyl ethoxypropionate, propyl 3-ethoxypropionate, butyl 3-ethoxypropionate and the like. Examples of ethers include tetrahydrofuran.

[Adjustment of Resin Composition] The photocurable resin composition for an optical disk of the present invention is prepared by uniformly mixing the respective compositions and having a viscosity of 0.01 to 500 Pa · s at 25 ° C. . In the viscosity range of 0.01 to 500 Pa · s, the coating workability can be more efficiently performed. The viscosity range is
The pressure is more preferably 0.1 to 100 Pa · s. The viscosity can be adjusted by the ratio of (A) the cationically polymerizable monomer and (B) the cationically polymerizable copolymer, and a diluent can be used.

[Method of Forming Recording Layer and Optical Recording Disc] In the present invention, the method of forming the recording layer is as follows. First, the composition of the present invention, whose viscosity has been adjusted, is uniformly coated on a transparent substrate made of polycarbonate or the like by spin coating.・ Apply evenly by screen printing ・ After applying on release paper prepared in advance, diluent is evaporated to form a uniform film, and it is transparent on the transparent substrate by a method such as transferring to a transparent substrate To form a thin film of a suitable composition. As the transparent substrate, a polyester resin such as triacetyl cellulose, polymethyl methacrylate, or polyethylene terephthalate, or an aromatic polyester resin such as a polyarylate resin can be used in addition to polycarbonate.

Next, the recording layer is transferred to a thin film of the above composition using a stamper made of nickel or the like. At this time, the number P
Pressurize with a. In that state, irradiate light from the transparent substrate surface,
The thin film of the composition of the present invention is cured to form a recording layer.

The light source that can be used here may be any light source that can be cured within a predetermined working time. Usually, a light source capable of emitting light in the range of ultraviolet light and visible light is used, and specific examples thereof include a low-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp, and a metal halide lamp. In addition, the normal irradiation light amount is 200 to 3000 mJ.
/ Cm ² . There is no particular upper limit to the irradiation amount, but an excessive amount is not preferable because unnecessary energy is wasted and productivity is reduced.

Thereafter, the stamper is removed, silicon oxide is sputtered on the surface of the recording layer to form a transparent reflective layer, and then the same recording layer forming process is repeated. After forming the desired number of layers, a transparent substrate is attached to complete the optical recording disk.

[0037]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. <Synthesis of Cationic Polymerizable Copolymer 1> 200 g of toluene was charged into a separable flask equipped with a cooling tube, two feed ports, and a thermometer, and purged with nitrogen. 120 ° C under stirring
6 g of perbutyl octanoate and 0.4 g of n-dodecyl mercaptan from the feed port 1, 40 g of glycidyl methacrylate, 40 g of methyl methacrylate, and 2-ethylhexyl acrylate 1 from the feed port 2.
20 g of the mixture are each continuously fed for 4 hours.
After addition of 1 g of perbutyl octanoate,
The polymerization was continued for a period of time to obtain a cationically polymerizable copolymer 1 (a toluene solution having a solid content of 50.8%). The number average molecular weight of this cationically polymerizable copolymer 1 was 8000 (GPC: in terms of polystyrene), and Tg was −32 ° C. (viscoelasticity measuring device).

<Synthesis of Cationic Polymerizable Copolymers 2 to 5> The cationic polymerizable copolymers 2 to 5 were prepared in the same manner as in the method of synthesizing the cationic polymerizable copolymer 1 except that the compositions shown in Table 1 were used. Was synthesized.

Example 1 30 g of 3-ethyl-3-hydroxymethyloxetane, 70 g of the cationically polymerizable copolymer 1 and 1 g of diphenyl-4-thiophenoxyphenylsulfonium were stirred and mixed in a brown glass container. The product 1 was obtained. After the composition 1 was applied to release paper,
After drying for a minute, the toluene was evaporated to form a uniform film having a thickness of 40 μm, which was used in Evaluations 1-4 below.

(Evaluation method) [1 Light transmittance test] After transferring composition 1 in the form of a film to a polycarbonate substrate, the polycarbonate substrate was bonded and irradiated with ultraviolet rays (high-pressure mercury lamp: Toskure 251 (manufactured by Toshiba Lighting & Technology)). And cured. The transmittance of the bonded substrates was measured at 380 nm to 800 nm using an ultraviolet-visible spectrophotometer, and the lowest value of the transmittance and the wavelength thereof are shown in Table 2. [2 Moldability evaluation test by stamper] After transferring the composition 1 formed into a film onto a polycarbonate substrate, the pressure was set to 0.5 MPa and 50 ° C using a nickel stamper.
Was used to transfer the pattern. Nickel stamper is uneven 1
The thing of 80 nm was used. Irradiation of ultraviolet light from the polycarbonate substrate surface (high-pressure mercury lamp: Toskure 251
(Manufactured by Toshiba Lighting & Technology)) and cured, and the pattern formed on the composition 1 after the stamper was peeled off was observed with an AFM (atomic force microscope).
Displayed. The results are shown in Table 2. [3 Adhesion Test] After transferring the composition 1 in the form of a film to a polycarbonate substrate, the polycarbonate was bonded and irradiated with ultraviolet rays (high-pressure mercury lamp: Toscure 25).
1 (manufactured by Toshiba Lighting & Technology)). The peel strength of the bonded polycarbonate substrate was measured. The results are shown in Table 2. [4 Stamper Peelability Test] In the same manner as in Evaluation Method 3, a recording layer was formed with a stamper, and the ease of peeling when the stamper was peeled off after curing was evaluated in the following three grades. ○ The disk was easily peeled without any abnormality in appearance. △ The disk was not distorted, but the disk was difficult to peel. × The disk was distorted. The results are shown in Table 2.

(Example 2-10) A composition was obtained according to Example 1 except that the composition shown in Table 2 was used, and the composition was evaluated. Table 2 shows the results.

[0042]

[Table 1]

[0043]

[Table 2]

<Synthesis of urethane acrylate oligomer> 100 g of isophorone diisocyanate and 0.4 g of di-n-butyltin dilaurate were charged into a separable flask equipped with a thermometer, a feed port and a stirrer, and kept at 20 ° C. in a dry air atmosphere at a constant temperature. -Feed 50 g of hydroxyethyl acrylate in one hour. Thereafter, 240 g of polytetramethylene glycol having a hydroxyl value of 109.7 mgKOH / g is added all at once. After reacting at 50 ° C. for 3 hours, an oligomer having a number average molecular weight of 2,000 was synthesized.

(Comparative Example 1-5) A composition was obtained and evaluated in the same manner as in Example 1, except that the composition shown in Table 3 was used. Table 3 shows the results.

[0046]

[Table 3]

[0047]

The composition of the present invention has a moldability and a function as an adhesive for bonding a double-sided transparent substrate, and further provides a material having excellent transparency without absorption in a wavelength range of 380 to 800 nm. Made it possible.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) G11B 7/24 522 G11B 7/24 522Y 522P (72) Inventor Yugo Yamamoto 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Address F-term in Mitsui Chemicals, Inc. (reference) 4J036 AB01 AB02 AB10 AD08 AJ09 AJ24 AK11 DB30 FB03 GA01 GA03 GA07 HA02 JA15 4J100 AL08P AL10P BC53P CA01 CA04 HA19 HA53 HC38 HC39 HE22 HE41 JA36 5D029 JB13 KB07

Claims (7)

[Claims] 1. A resin composition for forming a recording layer of a multilayer optical recording disk comprising two or more layers, wherein (A) a cationically polymerizable monomer and (B) a glass transition temperature (Tg) of 2
A photocurable resin composition for an optical disc, comprising: a cationically polymerizable copolymer having a temperature of 0 ° C. or lower; and (C) a photoinitiator. 2. The photocurable resin composition for an optical recording disk according to claim 1, wherein (A) the cationically polymerizable monomer is a compound or a mixture having an oxetane ring and / or an oxirane ring in the molecule. object. 3. The compound having an oxirane ring in the cationic polymerizable monomer (A) is at least one compound selected from bisphenol glycidyl ether, alicyclic epoxy compound and aliphatic glycidyl ether. The photocurable resin composition for an optical recording disk according to claim 2. 4. The optical recording according to claim 1, wherein the cationic polymerizable copolymer (B) is an acrylic copolymer containing oxetanyl (meth) acrylate and / or glycidyl (meth) acrylate. Photocurable resin composition for disks. 5. The photocurable resin composition for an optical recording disk according to claim 1, wherein the photoinitiator (C) is an onium salt. 6. The content of the resin composition is (A) 30 to 69.7% by mass of a cationically polymerizable monomer, (B) 63 to 30% by mass of a cationically polymerizable copolymer, and (C) a photoinitiator 7. The photocurable resin composition for an optical disk according to any one of claims 1 to 5, wherein the content is from 0.1 to 0.3% by mass. 7. An optical recording disk obtained by using the photocurable resin composition according to claim 1.