JP2003277697A - Photocurable adhesive sheet and method for producing optical information-recording medium using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable adhesive sheet that can simply and exactly transfer an uneven face of a stamper for making an optical information- recording medium by pressure, and provide a method for making the optical information-recording medium by using the photocurable adhesive sheet. <P>SOLUTION: The photocurable adhesive sheet comprises a photocurable composition containing photopolymerizable oligomers having glass transition points of ≤20°C and has a photocurable adhesive layer with a light transmittance of ≥70% in the wavelength region of 380-420 nm. Optical information- recording base plates and optical information-recording media are provided by using the adhesive sheet. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable adhesive sheet, in particular, a DVD (Digital Versatile Disc), a magneto-optical disk, a hard disk or the like having a large capacity of information such as characters, voices and moving images recorded as digital signals. The present invention relates to a photocurable adhesive sheet that can be advantageously used in a manufacturing process of a recordable and / or recordable optical information recording medium, and a method for manufacturing an optical information recording medium using the same.

[0002]

2. Description of the Related Art As a recorded optical information recording medium having pits formed on the surface as a digital signal, a CD-ROM
Although widely used, recently, a DVD having pit recording on both sides capable of recording a moving image has attracted attention as a next-generation recording medium for a CD and is gradually being used. In addition, a user-recordable CD-R, DVD-R, DVD-RW, etc., in which pits and grooves are formed, is also receiving attention. Magneto-optical disks and hard disks are also known as user recordable media.

For example, in the production of a double-sided read DVD, a polycarbonate resin is melted by using a stamper in which the irregularities of the signal pits are opposite male and female, and a transparent resin substrate having irregularities on the surface is formed by injection molding. A reflective layer is formed by vapor-depositing a metal such as aluminum on the uneven surface by sputtering or the like, and two transparent resin substrates on which the reflective layer is formed are opposed to each other and are bonded with an adhesive. Was done by.
A liquid ultraviolet curable resin is generally used for such an adhesive.

In the manufacture of the optical information recording medium such as the DVD, the bonding step such as the bonding of the substrate as described above is usually necessary. Since the optical information recording medium records and reads information by light, it is required that the obtained substrate has a uniform thickness, is free from deformation such as warpage, and is transparent. When the liquid UV-curable resin is used as an adhesive, the resulting adhesive layer has good transparency, but has a large curing shrinkage and is liable to cause warpage and the like, which causes a problem of dimensional stability. There are cases.

In Japanese Patent Laid-Open No. 11-273147, a pressure-sensitive adhesive sheet or a dry photopolymer is used in addition to a liquid ultraviolet curable resin for adhering an injection-molded substrate having irregularities on its surface and a transparent film. is doing.
However, it is described that dry photopolymer is not preferable because of its low transparency.

On the other hand, with the increase in the amount of information to be recorded, a new optical information recording medium having a larger storage capacity than the currently used DVD has been proposed. In order to realize it, it is necessary not only to make the signal pits and grooves small, but also to shorten the wavelength of the reproducing laser (or writing laser) for signal reading. Since the distance becomes shorter, it is necessary to reduce the thickness of the optical information recording substrate. For this reason, it is desirable that the adhesive layer used be thin.

[0007]

SUMMARY OF THE INVENTION An object of the present invention made in view of the above point is to provide a photocurable adhesive sheet which can be advantageously used for producing an optical information recording medium.

Another object of the present invention is to provide a photocurable adhesive sheet having excellent dimensional stability and high transparency.

A further object of the present invention is to provide a method for manufacturing an optical information recording medium using the above photocurable adhesive sheet.

[0010]

[Means for Solving the Problems] The above object comprises a photocurable composition containing a reactive polymer having a photopolymerizable functional group and having a glass transition temperature of 20 ° C. or lower.
It can be achieved by a photocurable adhesive sheet having a light transmittance of 70% or more in a wavelength region of ˜420 nm.

In the above photocurable adhesive sheet, the reactive polymer preferably has a glass transition temperature of 20 ° C. or lower. This makes it easy to form irregularities by pressing at room temperature. The photocurable adhesive sheet preferably has a light transmittance of 80% or more in the wavelength range of 380 to 420 nm. Also preferably 380 to 600 nm, particularly 380 to
The light transmittance in the wavelength region of 800 nm is preferably 70% or more. When a signal is read by a laser on the resulting medium, error-free operation is guaranteed. The photo-curable adhesive layer preferably has a cure shrinkage of 8% or less.

The reactive polymer is preferably an acrylic resin. The reactive polymer preferably contains 1 to 50 mol% of a photopolymerizable functional group. The photopolymerizable functional group is preferably a (meth) acryloyl group.
A particularly preferred reactive polymer is an acrylic resin having a photopolymerizable group via a urethane bond. The photocurable composition generally contains 0.1 to 10% by mass of a photopolymerization initiator. The thickness of the photocurable adhesive layer is preferably 5 to 300 μm. It is preferable that a release sheet is attached to at least one surface (particularly both surfaces) of the photocurable adhesive sheet.

Further, according to the present invention, two optical information recording substrates having concave and convex surfaces as recording pits and / or grooves are pressed with the concave and convex surfaces facing each other through the above photocurable adhesive sheet, Then, there is also a method for producing an optical information recording medium, which is characterized by photo-curing.

In the above method, it is preferable that the pressing is performed under reduced pressure, and that the pressing is performed at room temperature.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an example of an embodiment of the photocurable adhesive sheet of the present invention.

FIG. 1 is a sectional view showing an example of an embodiment of a photocurable adhesive sheet 11 used in the present invention. The photocurable adhesive sheet 11 has release sheets 12a and 12b on both sides.
Have. Only one release sheet may be provided, or no release sheet may be provided.
It is set appropriately depending on the usage. Providing release sheets on both sides is advantageous because it facilitates handling.

In FIG. 1, a photocurable adhesive sheet 11
Is a layer that can be deformed along the uneven surface of the optical information recording substrate by pressing the uneven surface of the optical information recording substrate, and has a photopolymerizable functional group having a glass transition temperature of 20 ° C. or less. It is mainly composed of a photocurable composition containing a reactive polymer. The layer has a light transmittance of 70% or more in a wavelength range of 380 to 420 nm so that it can be easily read by a reproducing laser. Especially 380
The light transmittance in the wavelength region of 420 nm is preferably 80% or more. Therefore, the optical information recording medium produced by using this adhesive sheet can be advantageously used in the method of reproducing a pit signal using a laser having a wavelength of 380 to 420 nm.

Since the photo-curable adhesive sheet of the present invention is flexible so that it can be pressure-bonded even at room temperature as described above, it is extremely easy to use, and therefore CD, DVD, C
D-R, DVD-R, DVD-RW, magneto-optical disk,
It can be widely used for various purposes as well as a medium in the information recording field such as a hard disk. It is particularly suitable for fields requiring precise bonding, and can be used, for example, in the manufacture of electrical appliances, furniture, automobiles, musical instruments, sports equipment, packaging materials and the like.

An optical information recording medium can be manufactured using the above photocurable adhesive sheet, for example, as shown in FIG. 2 below.

A photocurable adhesive sheet 11 from which the release sheet 12a has been removed is prepared. The reflection layer 23 on the uneven surface of the optical information recording substrate 21 having unevenness as recording pits on the surface
The photo-curable adhesive sheet 11 is pressed against (a generally reflective layer having a high reflectance such as Al and Ag) with the side without the release sheet. As a result, the laminate (12b, 11, 12) in which the surface of the photocurable adhesive sheet is closely attached along the uneven surface
3, 21) is formed. The release sheet 12b is removed from this laminate.

Next, a reflection layer (or a semitransparent reflection layer) 25 on the uneven surface of another optical information recording substrate 24 having unevenness as recording pits on the surface is uncured with the release sheet 12b removed and is uncured. The surface of the adhesive sheet 11 (the surface on the side not in contact with the substrate) is pressed. The surface of the photocurable adhesive sheet 11 is adhered along the uneven surface of the optical information recording substrate 24 to form a laminate (consisting of 21, 23, 11, 24 and 25), and the photocurability of the laminate is formed. The transfer sheet was cured by UV irradiation. Thereby, an optical information recording medium is obtained.

Alternatively, as shown in FIG. 3, the optical information recording substrate 21 having concaves and convexes as recording pits on the surface thereof is light-curable adhesive with the side without the release sheet facing the reflecting layer 23 on the concave and convex surface. After placing the sheet 11, without pressing it,
The release sheet 12b is removed, then another optical information recording substrate 24 is placed on the release sheet 12b, and these are pressed at once to form the optical information recording substrate 24 having two surfaces of the photocurable adhesive sheet 11.
Forming a laminated body adhered along the two uneven surfaces of
Then, the photocurable transfer sheet of this laminate may be cured by irradiation with ultraviolet rays.

In the above process, a protective polymer sheet may be attached instead of another optical information recording substrate. In this case, there is only one uneven surface. Alternatively, a (photo-curable or adhesive) transfer sheet is attached on the reflection layer of the uneven surface of the optical information recording substrate having unevenness as recording pits on the surface, and a stamper is pressed thereon to form the unevenness ( It may be cured if necessary) to prepare a substrate having two uneven surfaces, and a protective polymer sheet may be attached to the exposed uneven surface via a photocurable adhesive sheet.

In the above method, the production of the read-only optical information recording medium has been described, but the same can be applied to a recordable optical information recording medium. A recordable optical information recording medium has a groove or a groove and a pit. In this case, a metal recording layer (in the case of a dye recording layer, a recording layer and a reflective layer) is used instead of the reflective layer and the semitransparent reflective layer. It is provided. Otherwise, the optical information recording medium can be manufactured in the same manner as above.

The optical information recording substrate may be manufactured by a conventional injection molding method, or may be manufactured by pressing a stamper on the photocurable adhesive sheet, the pressure sensitive adhesive sheet or the like of the present invention. As a result, a thin substrate having a thickness of 300 μm or less can be obtained.

In the above manufacturing method, when the photocurable adhesive sheet is pressed against the substrate, or two optical information recording substrates are
When the reflective layers are arranged so as to face each other, and when they are superposed with the adhesive sheet interposed therebetween, it is preferable to perform pressing or superposition under reduced pressure. As a result, removal of bubbles and the like are smoothly performed.

The pressing under the reduced pressure is, for example, 2 times under the reduced pressure.
A method of passing a substrate and a photocurable adhesive sheet, or a substrate / adhesive sheet / substrate between individual rolls; or using a vacuum forming machine, placing the substrate in a mold and depressurizing the photocurable adhesive sheet And a method of placing the substrate in a mold and press-bonding the photocurable adhesive sheet and the substrate to the substrate while depressurizing the substrate.

Further, it is possible to perform pressing under reduced pressure by using a double vacuum chamber type device. This will be described with reference to FIG. FIG. 4 shows an example of a double vacuum chamber type laminator. The laminator includes a lower chamber 41, an upper chamber 42, a silicone rubber sheet 43, and a heater 45. In a lower chamber 41 in the laminator, a laminate (or a substrate / adhesive sheet / substrate laminate) 49 including a substrate having irregularities and a photocurable adhesive sheet placed thereon is placed. Both the upper chamber 42 and the lower chamber 41 are evacuated (decompressed). The laminated body 49 is heated by the heater 45, and then the upper chamber 42 is returned to the atmospheric pressure while the lower chamber 41 is exhausted, and the laminated body is pressure-bonded. After cooling, the laminate is taken out and transferred to the next step. Thereby, degassing is sufficiently performed at the time of evacuation, and the substrate and the photocurable adhesive sheet can be pressure-bonded to each other without bubbles.

The photocurable adhesive layer of the photocurable adhesive sheet of the present invention comprises a photocurable composition containing a reactive polymer having a photopolymerizable functional group having a glass transition temperature of 20 ° C. or lower. The photocurable composition generally comprises a reactive polymer having the above-mentioned photopolymerizable functional group, a compound (monomer and oligomer) having a photopolymerizable functional group (preferably (meth) acryloyl group), a photopolymerizable initiator and , If desired, composed of other additives.

Examples of the reactive polymer having a photopolymerizable functional group include alkyl acrylate (eg, methyl acrylate, ethyl acrylate, butyl acrylate,
2-ethylhexyl acrylate) and / or alkyl methacrylate (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate), a homopolymer or copolymer (ie, acrylic resin), and a main chain or side chains. Examples thereof include those having a photopolymerizable functional group in the chain. Such a polymer is obtained, for example, by copolymerizing one or more kinds of (meth) acrylate with (meth) acrylate having a functional group such as a hydroxyl group (eg, 2-hydroxyethyl (meth) acrylate). It can be obtained by reacting a polymer with a functional group of the polymer and a compound having a photopolymerizable group, such as an isocyanatoalkyl (meth) acrylate. Therefore, an acrylic resin having a photopolymerizable functional group via a urethane bond is preferable.

The above reactive polymer of the present invention preferably contains a photopolymerizable functional group in an amount of generally 1 to 50 mol%, particularly 5 to 30 mol%. The photopolymerizable functional group is preferably an acryloyl group, a methacryloyl group, a vinyl group,
Particularly, an acryloyl group and a methacryloyl group are preferable.

The glass transition temperature of this reactive polymer is generally 20 ° C. or lower, and the glass transition temperature is 20 ° C.
By the following, when the obtained photocurable adhesive layer is pressure-bonded to the uneven surface of the stamper, it is possible to have flexibility capable of closely following the uneven surface. In particular, when the glass transition temperature is in the range of 15 ° C to -50 ° C, the followability is excellent. If the glass transition temperature is too high, a high pressure is required at the time of sticking, which leads to a reduction in workability, and if it is too low, a sufficient altitude cannot be obtained after curing.

Further, the reactive polymer of the present invention generally has a number average molecular weight of 5,000 to 1,000,000, preferably 10,000 to 300,000, and a weight average molecular weight of generally 5,000 to 1,000,000, preferably 10.
It is preferably 000 to 300,000.

Specific examples of the compound having a photopolymerizable functional group include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and 2-
Ethylhexyl polyethoxy (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, phenyloxyethyl (meth) acrylate, tricyclodecane mono (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, tetrahydrofurfuryl (Meth) acrylate, acryloylmorpholine, N-vinylcaprolactam, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, o-phenylphenyloxyethyl (meth) acrylate, neopentyl glycol di (meth) acrylate, neopentyl glycol Dipropoxydi (meta)
Acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, trimethylolpropane tri ( (Meth) acrylate, pentaerythritol tri (meth)
(Meth) acrylate monomers such as acrylate, pentaerythritol tetra (meth) acrylate, tris [(meth) acryloxyethyl] isocyanurate, and ditrimethylolpropane tetra (meth) acrylate, polyol compounds (eg, ethylene glycol,
Propylene glycol, neopentyl glycol, 1,
6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-
Butyl-1,3-propanediol, trimethylolpropane, diethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-dimethylolcyclohexane, bisphenol A polyethoxydiol, polytetramethylene glycol, and other polyols,
Polyester polyols which are the reaction products of the above polyols with polybasic acids such as succinic acid, maleic acid, itaconic acid, adipic acid, hydrogenated dimer acid, phthalic acid, isophthalic acid, terephthalic acid or their acid anhydrides. A polycaprolactone polyol which is a reaction product of the polyols and ε-caprolactone, a reaction product of the polyols and the ε-caprolactone of the polybasic acid or these acid anhydrides, a polycarbonate polyol, a polymer polyol, etc. ) And an organic polyisocyanate (for example,
Tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane-
4,4'-diisocyanate, dicyclopentanyl diisocyanate, hexamethylene diisocyanate, 2,
4,4'-trimethylhexamethylene diisocyanate, 2,2'-4-trimethylhexamethylene diisocyanate and the like) and a hydroxyl group-containing (meth) acrylate (for example, 2-hydroxyethyl (meth) acrylate, 2-
Hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3
-Phenyloxypropyl (meth) acrylate, cyclohexane-1,4-dimethylol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, glycerin di (meth) acrylate, etc.), a polyurethane (meth) acrylate, Examples thereof include (meth) acrylate oligomers such as bisphenol type epoxy (meth) acrylate which is a reaction product of bisphenol type epoxy resin such as bisphenol A type epoxy resin and bisphenol F type epoxy resin and (meth) acrylic acid. These compounds having a photopolymerizable functional group can be used alone or in combination of two or more.

As the photopolymerization initiator, any known photopolymerization initiator can be used, but one having good storage stability after blending is desirable. As such a photopolymerization initiator, for example, 2-hydroxy-2-methyl-1
-Phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, acetophenone such as 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, benzoin such as benzyldimethylketal, benzophenone , Benzophenone-based compounds such as 4-phenylbenzophenone and hydroxybenzophenone, thioxanthone-based compounds such as isopropylthioxanthone and 2-4-diethylthioxanthone, and other special ones such as methylphenylglyoxylate. Particularly preferably, 2-hydroxy-2-
Methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-
(4- (methylthio) phenyl) -2-morpholinopropane-1, benzophenone and the like can be mentioned. These photopolymerization initiators may optionally contain one or more known benzoic acid-based accelerators such as 4-dimethylaminobenzoic acid or known conventional photopolymerization accelerators such as tertiary amines. It can be mixed and used in a ratio. Further, the photopolymerization initiator alone can be used alone or in combination of two or more kinds. A photopolymerization initiator is generally added to the photocurable composition in an amount of 0.1
It is preferable to contain -20 mass%, especially 1-10 mass%.

Among the photopolymerization initiators, examples of the acetophenone-based polymerization initiator include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone, diethoxyacetophenone, 2- Hydroxy-2-methyl-
1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropane-1 -One, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-
Propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, and the like, benzophenone-based polymerization initiators such as benzophenone, benzoylbenzoic acid, and benzoylbenzoic acid. Acid methyl, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide,
3,3'-Dimethyl-4-methoxybenzophenone and the like can be used.

As the acetophenone type polymerization initiator, particularly, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- (4- (methylthio) phenyl ) -2-Morpholinopropane-1 is preferred. The benzophenone-based polymerization initiator is preferably benzophenone, benzoylbenzoic acid or methyl benzoylbenzoate. Further, as a tertiary amine photopolymerization accelerator, triethanolamine, methyldiethanolamine, triisopropanolamine, 4,4′-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone, ethyl 2-dimethylaminobenzoate. , Ethyl 4-dimethylaminobenzoate, (n-butoxy) ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate and the like can be used. Particularly preferably, the photopolymerization accelerator is ethyl 4-dimethylaminobenzoate, 4-
Dimethylaminobenzoate (n-butoxy) ethyl, 4-
Examples include isoamyl dimethylaminobenzoate and 2-ethylhexyl 4-dimethylaminobenzoate. As described above, the components of the photopolymerization initiator are used by combining the above three components.

The photocurable composition is designed so that the photocurable adhesive sheet of the present invention has a glass transition temperature of 20 ° C. or lower and a transmittance of 70% or higher for light having a wavelength of 380 to 420 nm. Is preferred. Therefore, in addition to the compound having a photopolymerizable functional group and the photopolymerization initiator,
If desired, the following thermoplastic resins and other additives are preferably added.

The mass ratio of the above reactive polymer: compound having a photopolymerizable functional group: photopolymerization initiator is generally 4
0 to 100: 0 to 60: 0.1 to 10, especially 60 to 10
It is preferably from 0: 0 to 40: 1 to 10.

A silane coupling agent (adhesion promoter) can be added as another additive. Examples of the silane coupling agent include vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy. Propyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (Aminoethyl) -γ-aminopropyltrimethoxysilane and the like, and one of these may be used alone or two or more of them may be used in combination. The addition amount of these silane coupling agents is the above-mentioned reactive polymer 1
Usually, 0.01 to 5 parts by weight is sufficient with respect to 00 parts by weight.

Similarly, an epoxy group-containing compound can be added for the purpose of improving the adhesiveness. Examples of the epoxy group-containing compound include triglycidyl tris (2-hydroxyethyl) isocyanurate; neopentyl glycol diglycidyl ether; 1,6-hexanediol diglycidyl ether; acryl glycidyl ether;
2-ethylhexyl glycidyl ether; phenyl glycidyl ether; phenol glycidyl ether; p-
t-butylphenyl glycidyl ether; adipic acid diglycidyl ester; o-phthalic acid diglycidyl ester; glycidyl methacrylate; butyl glycidyl ether and the like. The same effect can be obtained by adding an oligomer containing an epoxy group having a molecular weight of several hundred to several thousand or a polymer having a weight average molecular weight of several thousand to several hundred thousand. The addition amount of these epoxy group-containing compounds is 0.1 to 20 with respect to 100 parts by weight of the above reactive polymer.
The weight part is sufficient, and at least one of the epoxy group-containing compounds may be added alone or in combination.

As another additive, a hydrocarbon resin may be added for the purpose of improving workability and workability such as bonding. In this case, the added hydrocarbon resin may be a natural resin type or a synthetic resin type. As the natural resin type, rosin, rosin derivative and terpene type resin are preferably used. For rosin, gum resin, tall oil resin,
Wood-based resin can be used. As the rosin derivative, those obtained by hydrogenating, heterogenizing, polymerizing, esterifying, or metallizing rosin can be used. As the terpene-based resin, a terpene-based resin such as α-pinene and β-pinene, and a terpene-phenolic resin can be used. Further, other natural resins such as dammar, cobal and shellac may be used. On the other hand, petroleum-based resins, phenol-based resins, and xylene-based resins are preferably used in the synthetic resin system. As the petroleum resin, aliphatic petroleum resin, aromatic petroleum resin, alicyclic petroleum resin, copolymer petroleum resin, hydrogenated petroleum resin, pure monomer petroleum resin, and coumarone indene resin can be used. As the phenol resin, an alkylphenol resin or a modified phenol resin can be used. As the xylene-based resin, a xylene resin or a modified xylene resin can be used.

Acrylic resins can also be added. For example, alkyl acrylate (eg, methyl acrylate, ethyl acrylate, butyl acrylate) and /
Alternatively, a homopolymer or a copolymer obtained from an alkyl methacrylate (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate) can be mentioned. Moreover, the copolymer of these monomers and another copolymerizable monomer can also be mentioned. In particular, polymethyl methacrylate (PMMA) is preferable in terms of reactivity during photocuring, durability after curing, and transparency.

The amount of the polymer such as the above-mentioned hydrocarbon resin added is appropriately selected, but it is preferably 1 to 20 parts by weight, more preferably 5 to 100 parts by weight of the reactive polymer.
15 parts by weight.

In addition to the above additives, the photocurable composition of the present invention may contain a small amount of an ultraviolet absorber, an antioxidant, a dye, a processing aid and the like. Further, in some cases, a small amount of additives such as silica gel, calcium carbonate, and fine particles of silicon copolymer may be included.

The photocurable adhesive sheet comprising the photocurable composition of the present invention comprises the above-mentioned reactive polymer, a compound having a photopolymerizable functional group (monomer and oligomer) and, if desired, other additives. It can be used after being formed into a predetermined shape by a film-forming method such as calendering, roll, T-die extrusion, inflation, etc. When using a support, it is necessary to form a film on the support. A more preferable method of forming a photocurable adhesive film of the present invention is to uniformly mix and dissolve the respective constituent components in a good solvent, and use a flow coating method or a roll coating method for a separator that is precisely coated with this solution of silicone or fluororesin. , A gravure roll method, a Mayer bar method, a lip die coating method or the like, and a method of forming a film by drying the solvent.

In film formation, blocking prevention,
Embossing may be applied to facilitate deaeration during pressure bonding with the support or stamper. A known method can be adopted as the embossing method, and for example, embossing with a roll or the like. In the case of the solution coating method, the emboss can be transferred by coating on an embossed film (paper) having releasability. The average roughness (Ra) of this emboss is 50 μm or less, more preferably 0.01 to 50 μm, still more preferably 0.1 to 20 μm.
It is preferable to form the irregularities, which allows air to easily escape from the bonding surface with the device, and to fill the complicated irregularities on the device surface. If it is less than 0.01 μm, deaeration failure is likely to occur, and if it is more than 50 μm, unevenness may remain during temporary pressure bonding.

The thickness of the photocurable adhesive layer is generally 1 to
1200 μm, further 5-500 μm, especially 5-300
It is preferably set to μm. When the thickness is less than 1 μm, the sealing property is poor and the irregularities of the transparent resin substrate may not be completely filled. On the other hand, if it is thicker than 1000 μm, the thickness of the recording medium increases, which may cause problems in storage of the recording medium, assembly, and the like, and may also affect light transmission.

The material of the release sheet used in the present invention is preferably a transparent organic resin having a glass transition temperature of 50 ° C. or higher. Examples of such a support include polyethylene terephthalate, polycyclohexylene terephthalate,
Polyester resin such as polyethylene naphthalate, nylon 46, modified nylon 6T, nylon MXD6, polyamide resin such as polyphthalamide, ketone resin such as polyphenylene sulfide and polythioether sulfone, sulfone such as polysulfone and polyether sulfone In addition to the system resin, it is possible to use a transparent resin substrate whose main component is an organic resin such as polyether nitrile, polyarylate, polyether imide, polyamide imide, polycarbonate, polymethyl methacrylate, triacetyl cellulose, polystyrene, and polyvinyl chloride. it can. Of these, polycarbonate, polymethylmethacrylate, polyvinyl chloride, polystyrene, and polyethylene terephthalate can be preferably used. The thickness is preferably 10 to 200 μm, particularly 30
˜100 μm is preferred.

A transparent organic resin having a glass transition temperature of 50 ° C. or higher is preferable as a material for the substrate having irregularities on its surface. As such a support, polyethylene terephthalate, polycyclohexylene terephthalate, polyethylene naphthalate is preferable. Polyester resin such as nylon, nylon 46, modified nylon 6T, nylon MXD
6. In addition to polyamide resins such as polyphthalamide, polyphenylene sulfide, ketone resins such as polythioether sulfone, sulfone resins such as polysulfone and polyether sulfone, polyether nitrile,
A transparent resin substrate containing an organic resin such as polyarylate, polyetherimide, polyamideimide, polycarbonate, polymethylmethacrylate, triacetylcellulose, polystyrene, or polyvinyl chloride as a main component can be used. Among these, polycarbonate, polymethylmethacrylate, polyvinyl chloride, polystyrene, and polyethylene terephthalate are excellent in transferability and birefringence and can be preferably used. The thickness is preferably 200 to 2000 μm, particularly 500 to 15
00 μm is preferable.

As a material for the polymer film for protection, a transparent organic resin having a glass transition temperature of 50 ° C. or higher is preferable, and as such a support, a polyester such as polyethylene terephthalate, polycyclohexylene terephthalate or polyethylene naphthalate is used. -Based resins, nylon 46, modified nylon 6T, nylon MXD6, polyamide resins such as polyphthalamide, ketone resins such as polyphenylene sulfide and polythioether sulfone, sulfone resins such as polysulfone and polyether sulfone, Organic resin such as polyether nitrile, polyarylate, polyether imide, polyamide imide, polycarbonate, polymethyl methacrylate, triacetyl cellulose, polystyrene, polyvinyl chloride, etc. as the main component A transparent resin substrate can be used. Among these, polycarbonate, polymethylmethacrylate, polyvinyl chloride, polystyrene, and polyethylene terephthalate are excellent in transferability and birefringence and can be preferably used. Thickness is 10
To 200 μm is preferable, and 50 to 100 μm is particularly preferable.

The photocurable adhesive sheet of the present invention thus obtained comprises a photocurable composition containing a reactive polymer having a glass transition temperature of 20 ° C. or lower. It is preferable that the light transmittance in the wavelength region of up to 800 nm is 70% or more. That is, by setting the glass transition temperature to 20 ° C. or lower, when the photocurable adhesive sheet is pressure-bonded to the uneven surface of the substrate, it is possible to have flexibility capable of closely following the uneven surface even at room temperature. In particular, when the glass transition temperature is in the range of 15 ° C to -50 ° C, the followability is excellent. If the glass transition temperature is too high, high pressure and high temperature are required at the time of sticking, which leads to a reduction in workability, and if it is too low, a sufficient altitude after curing cannot be obtained.

The photocurable adhesive sheet has a thickness of 380 to 420 nm.
The light transmittance in the wavelength region (preferably 380 to 800 nm) is 70% or more, and this is to prevent the reduction in the intensity of the read signal by the laser. 380-4
The light transmittance in the wavelength region of 20 nm is preferably 80% or more.

The reactive polymer in the photocurable composition preferably has 1 to 50 mol% of a polymerizable functional group. As a result, the obtained photocurable adhesive layer can have a strength capable of retaining its shape after being cured. As described above, the photopolymerization initiator is preferably in the range of 0.1 to 10% by mass, and if it is less than this, the curing speed is too slow and the workability is poor, and if it is too much, the followability to irregularities or rough surfaces is reduced. To do.

Since the photocurable adhesive sheet of the present invention can be provided in the form of a film whose film thickness precision is precisely controlled, it can be easily and accurately bonded to an uneven surface such as a substrate. It is possible. In addition, this bonding is performed by a simple method such as a pressure roll or a simple press for 20 to 20 minutes.
After temporary pressure bonding at 100 ° C, it can be cured by light at room temperature for 1 to several tens of seconds, and since the laminate formed by the self-adhesive force peculiar to this adhesive hardly causes misalignment or peeling, it can be freely handled until photocuring. It has the feature that

In the case of curing the photocurable adhesive sheet of the present invention, many light sources which emit light in the ultraviolet to visible range can be adopted as the light source, for example, ultrahigh pressure, high pressure, low pressure mercury lamp, chemical lamp, xenon lamp, halogen lamp. , Mercury halogen lamps, carbon arc lamps, incandescent lamps, laser light and the like. The irradiation time is generally several seconds to several minutes, although it cannot be generally determined depending on the type of lamp and the strength of the light source.

Further, in order to accelerate the curing, the laminate is preliminarily 3
You may heat to 0-80 degreeC and irradiate this with an ultraviolet ray.

In the method for producing an optical information recording medium of the present invention, these operations are usually continuously performed in a sheet shape, and finally punched into a disc shape, but punched before laminating and processed into a disc shape. Good.

[0060]

The present invention will be described in more detail with reference to the following examples. [Example 1] <Preparation of photocurable adhesive sheet> (Preparation of reactive polymer) Formulation I 2-Ethylhexyl methacrylate 70 parts by mass Methyl methacrylate 20 parts by mass 2-Hydroxyethyl methacrylate 10 parts by mass Benzophenone 5 parts by mass Toluene 30 parts by mass Parts Ethyl acetate 30 parts by mass While stirring gently, the mixture having the above composition is treated at 60 ° C.
Polymerization was initiated by heating to 50 ° C. and stirred at this temperature for 10 hours to obtain an acrylic resin having a hydroxyl group on the side chain. Thereafter, 5 parts by mass of Karenz MOI (2-isocyanatoethyl methacrylate; manufactured by Showa Denko KK) was added, and the mixture was reacted at 50 ° C. under a nitrogen atmosphere with gentle stirring to give a photopolymerizable functional group-containing reactivity. Polymer solution 1
Got

The reactive polymer thus obtained had a Tg of 0 ° C. and had 5 mol% of methacryloyl groups in its side chain.

Formulation II Reactive polymer solution 1 100 parts by mass Tricyclodecane diacrylate 30 parts by mass 1-hydroxycyclohexyl phenyl ketone 1 part by mass The mixture of the above composition is uniformly dissolved and a release sheet (thickness 75 μm; trade name No. .23, manufactured by Fujimori Industry Co., Ltd., to form a photocurable adhesive layer having a dry thickness of 25 ± 2 μm. Thereby, a photocurable adhesive sheet having a thickness of 100 ± 2 μm was obtained.

<Preparation of One Optical Information Recording Substrate with Reflective Layer> A photocurable transfer sheet was prepared in the same manner as the above photocurable adhesive sheet, and had a dry thickness 10 thicker than that of the adhesive sheet.
A film having a thickness of 0 μm was prepared.

Using the above-mentioned photocurable transfer sheet, the photocurable adhesive sheet is pressed with a load of 2 kg onto the concavo-convex surface of a nickel stamper having a concavo-convex surface as a pit using a silicone rubber roller. Then, a laminate was formed, and the uneven shape of the stamper was transferred onto the surface of the transfer sheet.

Next, from the side of the photocurable adhesive sheet, using a metal halide lamp, the integrated light amount is 1000 mJ / cm.
UV irradiation was performed under the condition of ² to cure the adhesive sheet.

The stamper was peeled off and removed from the laminate, and a silver alloy was sputtered on the uneven surface of the cured photocurable adhesive sheet (optical information recording substrate) to form a semitransparent reflective layer of silver alloy. An optical information recording substrate with a reflective layer was obtained.

<Fabrication of Optical Information Recording Substrate with Another Reflective Layer) Polycarbonate is melted and solidified in a mold having an uneven surface as pits to give a thickness of 1100 μm.
m optical information recording substrate was molded. An Al reflective layer was formed by sputtering aluminum on the formed uneven surface. The other optical information recording substrate with a reflective layer was obtained.

<Preparation of Optical Information Recording Medium> The photocurable adhesive sheet obtained above is provided on one reflective layer of the two optical information recording substrates with a reflective layer obtained above and two reflective layers. The attached optical information recording substrate was attached to the reflective layers, and UV irradiation was performed using a metal halide lamp under the condition of an integrated light amount of 1000 mJ / cm ² to cure the adhesive sheet. Thereby, an optical information recording medium (DVD) was obtained.

Example 2 <Preparation of Photocurable Adhesive Sheet> (Preparation of Reactive Polymer) Formulation I ′ n-hexyl methacrylate 50 parts by mass 2-hydroxyethyl methacrylate 50 parts by mass benzophenone 5 parts by mass Toluene 30 parts by mass Ethyl acetate 30 parts by mass While stirring gently, the mixture having the above composition is mixed at 60 ° C.
Polymerization was initiated by heating to 50 ° C. and stirred at this temperature for 10 hours to obtain an acrylic resin having a hydroxyl group on the side chain. Thereafter, 50 parts by mass of Karenz MOI (2-isocyanatoethyl methacrylate; Showa Denko KK) was added and reacted at 50 ° C. with gentle stirring to give a solution 2 of a reactive polymer having a photopolymerizable group. Obtained.

The obtained reacted polymer had a Tg of 5 ° C. and had a methacryloyl group in the side chain of 50 mol%.

Formulation II ′ Reactive polymer solution 2 100 parts by weight 1,6-hexanediol dimethacrylate 10 parts by weight 1-hydroxycyclohexyl phenyl ketone 1 part by weight The mixture of the above formulation is uniformly dissolved and a release sheet (thickness 75 μm Then, it was applied on the product name No. 23, manufactured by Fujimori Industry Co., Ltd. to form a photocurable adhesive layer having a dry thickness of 25 ± 2 μm. Thereby, a photocurable adhesive sheet having a thickness of 100 ± 2 μm was obtained.

The following production of the optical information recording substrate with one reflection layer and the other optical information recording substrate with the reflection layer, and the production of the optical information recording medium were carried out in the same manner as in Example 1, whereby the optical information recording was carried out. A medium (DVD) was obtained.

[Comparative Example 1] An optical information recording medium was obtained in the same manner as in Example 1, except that one optical information recording substrate with a reflective layer was prepared as follows.

(Production of Optical Information Recording Substrate with One Reflective Layer) Polycarbonate is melted and solidified on a stamper having an uneven surface as pits to give a thickness of 100 ±.
A 2 μm optical information recording substrate was molded. A semi-transmissive reflective layer of silver alloy was formed by sputtering a silver alloy on the uneven surface of the optical information recording substrate. An optical information recording substrate with a reflective layer was obtained.

<Preparation of Optical Information Recording Medium> A commercially available photocurable liquid adhesive (SD-661, Dainippon Ink and Chemicals, Inc.) was applied to one reflective layer of the two optical information recording substrates with a reflective layer obtained above. Kogyo Co., Ltd.) was applied by a spin coating method, two optical information recording substrates with a reflective layer were attached to each other with the reflective layers, and the adhesive was photocured. Thereby, an optical information recording medium (DVD) was obtained.

<Evaluation of Optical Information Recording Substrate and Optical Information Recording Medium> (1) Light Transmittance (Wavelength Range of 380 to 800 nm) A photocurable adhesive sheet was used in accordance with JIS-K6717.
The light transmittance in the wavelength range of 0 to 800 nm was measured. 7
0% or more was ◯, and less than 70% was X.

(2) Light transmittance (wavelength region of 380 to 420 nm) A photo-curable adhesive sheet was used in accordance with JIS-K6717.
The light transmittance in the wavelength range of 0 to 420 nm was measured. 8
0% or more was ◯, and less than 80% was X.

(3) Land Roughness The smoothness of the land surface of the surface where the pits are formed is
It evaluated using FM (atomic force microscope). Those that were sufficiently smooth were rated as ◯, and those that were significantly lacking in smoothness were rated as x.

(4) Signal reading The reproduction waveform of the obtained optical information recording medium is set to a wavelength of 405 nm.
Measurement was performed by using the laser of No. 1 and the reproduced waveform obtained was compared with the waveform of the stamper used for manufacturing. The ones that matched the waveform of the stamper were marked with ◯, and those that almost did not match were marked with x.

The test results obtained are shown in Table 1.

[0081]

[Table 1] Example 1 Example 2 Comparative Example 1 Light transmittance (380-800nm) ○ ○ ○ Light transmittance (380-420nm) ○ ○ ○ Land roughness ○ ○ × Signal reading ○ ○ ×

[0082]

As is apparent from the above, the photocurable adhesive sheet of the present invention can be accurately bonded along the uneven surface of the optical information recording medium by pressing it on the uneven surface of the substrate. . Therefore, in the obtained optical information recording medium, the substrate is completely adhered to the uneven surface, so that the adhesion does not adversely affect the signal surface. Therefore,
The optical information recording medium obtained in this way has the excellent characteristic that an error during reproduction hardly occurs.

In addition, in the adhesion in the production of the optical information recording medium of the present invention, the thickness is 30 because the photo-curable adhesive sheet is used to bring it into close contact with the substrate by deformation due to softening and cure.
Adhesion in a thin layer of 0 μm or less is possible, more transparent than ordinary photo-curable resins, less shrinkage upon curing, and excellent in dimensional stability, so almost no deformation such as warpage occurs. It is possible to manufacture a non-optical information recording medium.

For example, the photocurable adhesive sheet of the present invention is
Thin layer (eg thickness unevenness of 25 μm ± 2 μm)
Is used as the adhesive layer, the thickness accuracy of the formed layer is higher than that in the case where the ultraviolet curable liquid resin is applied by spin coating to form the adhesive layer (in this case, the thickness unevenness is generally ± 5 μm). Is also excellent, which leads to improvement of the above-mentioned dimensional stability.

Since the photocurable adhesive sheet of the present invention has the above-mentioned excellent properties, it can be used not only for the production of the above optical information recording medium but also for adhesion in various fields. It is clear that

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a photocurable adhesive sheet of the present invention.

FIG. 2 is a cross-sectional view showing an example of a method for manufacturing an optical information recording medium of the present invention.

FIG. 3 is a cross-sectional view showing another example of the method for manufacturing the optical information recording medium of the present invention.

FIG. 4 is a schematic view for explaining a pressing method using a double vacuum chamber type device.

[Explanation of symbols]

11 Photocurable adhesive sheet 12a, 12b release sheet 23 Reflective layer 21, 24 Optical information recording substrate 25 Semi-transparent reflective layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takahito Inamiya             3-1-1 Ogawa Higashi-cho, Kodaira-shi, Tokyo Stock market             Company Bridgestone F-term (reference) 4J004 AA01 AA10 AB07 BA02 DB02                       FA01 FA05 FA08                 4J040 DF041 DF051 EC361 EF181                       EF291 EF301 GA01 JA09                       JB08 KA13 LA02 LA10 NA17                       NA19 NA21 PA32                 5D029 RA28 RA30 RA38                 5D121 AA07 FF03 FF09 FF11

Claims (13)

[Claims] 1. A photocurable composition comprising a reactive polymer having a photopolymerizable functional group and having a glass transition temperature of 20 ° C. or lower, and having a light transmittance of 70% or more in a wavelength region of 380 to 420 nm. A photo-curable adhesive sheet characterized in that 2. The glass transition temperature of the reactive polymer is 20.
The photocurable adhesive sheet according to claim 1, which has a temperature of not higher than ° C. 3. The photocurable adhesive sheet according to claim 1, which has a light transmittance of 80% or more in a wavelength range of 380 to 420 nm. 4. The photocurable adhesive sheet according to claim 1, which has a light transmittance of 70% or more in a wavelength range of 380 to 800 nm. 5. The photocurable adhesive sheet according to claim 1, wherein the reactive polymer is an acrylic resin. 6. The reactive polymer has a photopolymerizable functional group of 1
The photocurable adhesive sheet according to any one of claims 1 to 5, which comprises -50 mol%. 7. The photocurable adhesive sheet according to claim 6, wherein the photopolymerizable functional group is a (meth) acryloyl group. 8. The photocurable composition comprises a photopolymerization initiator of 0.1.
The photocurable adhesive sheet according to claim 1, wherein the photocurable adhesive sheet contains 1 to 10% by mass. 9. The thickness of the photocurable adhesive sheet is 5 to 300.
The photocurable adhesive sheet according to claim 1, which has a thickness of μm. 10. The release sheet is attached to at least one surface of the photocurable adhesive sheet.
The photocurable adhesive sheet according to any one of 1. 11. The photocurable adhesive sheet according to claim 1, wherein two optical information recording substrates having concave and convex surfaces as recording pits and / or grooves are made to face each other with their concave and convex surfaces facing each other. A method for manufacturing an optical information recording medium, which comprises pressing through a film and then photo-curing the film. 12. The method according to claim 11, wherein the pressing is performed while reducing the pressure.
The manufacturing method described in. 13. The method according to claim 11, wherein the pressing is performed at room temperature.
2. The manufacturing method according to 2.