JP2000345073A - Ultraviolet curing type composition and optical disk using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique which enables the production of a substrate having two information recording layers at its one side simply with good precision in producing an optical disk having a structure in which two substrates each having two information recording layers at its one side have been laminated. SOLUTION: In the ultraviolet curing type composition to be used in the production process of optical disks which comprises coating an ultraviolet curing type composition on a substrate in which pits corresponding to recording information have been formed, then curing the ultraviolet curing type composition, and successively releasing the cured coated film from the substrate to transfer the pits corresponding to the recording information on to the cured coated film, by rendering the modulus of the cured coated film at 30 deg.C not greater than 500 MPa, a cured coated film which meets the properties required for adhesion/releasability and transfer properties can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an ultraviolet-curable composition which is suitably used in a process for producing an optical disk having a plurality of information recording layers. More specifically, a thickness of 0.
For the production of DVD-18 or DVD-14 having a structure in which a substrate having two information recording layers on one side of a DVD (digital video disk or digital versatile disk) made by bonding two 6 mm substrates together. The present invention relates to an ultraviolet curable composition preferably used and an optical disc manufactured using the composition.

2. Description of the Related Art DVD, which is a new type of optical disk having a bonding structure, is manufactured by bonding two disks having an information recording layer to at least one disk, and using an ultraviolet-curable composition as an adhesive. The method of using it is being actively studied.

In the case of a read-only DVD, four types of formats are officially certified. Among them, a typical product that has already been commercialized is to form irregularities called pits corresponding to recorded information on one side of a polycarbonate substrate, and further form a thin film of aluminum or the like as a laser light reflection film for reading information thereon. A DVD-10 in which two formed pieces are bonded together, one of which is a laser beam 1
There are three types, DVD-9 having a translucent film capable of reflecting 8 to 30% and transmitting the remainder, and DVD-5 using a substrate having no information recording layer. I have. However, two substrates having two information recording layers on one side
A DVD-18 having a laminated structure, a substrate which has not been officially certified but has recently been proposed, and a substrate having two information recording layers on one side and a substrate having one information recording layer. The DVD-14 having the combined structure has not yet been commercialized, and the manufacturing process is under study.

A typical structure of a DVD-18 is, for example,
0.6m thick with pits corresponding to the recorded information of
1) a semi-transparent reflective film (referred to as a reflective film 1) for reading the first recorded information, and 2) a laser beam for reading an information having a thickness of 45 to 70 μm. 3) A disk on which a reflective layer (referred to as a reflective film 2) for reading the second recording information is further laminated in order with a transparent layer (referred to as an intermediate layer) using an adhesive so that the reflective film 2 faces the disc. It has a laminated structure. The reflective film 1 reflects 18 to 30% of the laser light, and includes, for example, a metal such as gold, or a silicon-based inorganic material such as silicon, silicon nitride, or silicon carbide. The reflective film 2 is made of aluminum or an aluminum alloy.

[0003] In JP-A-10-283682, an ultraviolet curable resin is applied and cured on a metal stamper having second recording information, and an adhesive sheet serving as an intermediate layer is placed thereon, and the reflective film 1 is formed. A pressure-sensitive adhesive sheet is irradiated with ultraviolet light while applying pressure to a substrate having a thickness of 0.6 mm, and the adhesive sheet is adhered to the ultraviolet-cured film on the stamper and the reflective film 1. Then, only the metal stamper is peeled off and reflected on the exposed ultraviolet-cured film. There is disclosed a technique of forming a film 2 to form a substrate having two information recording layers on one side.

[0004] However, this method has problems that the process is complicated and productivity cannot be sufficiently ensured, and bubbles are involved in the adhesion of the pressure-sensitive adhesive sheet to easily form a defective disk, which is not satisfactory in practical use. Development of a method with higher productivity has been desired.

To meet this demand, "Tape / D
isc Business ”April 1999 (Knowledge Industry Publ
communications, Inc.), a pit corresponding to the first record information, a substrate 1 on which a translucent reflective film 1 for reflecting a laser beam for reading information is formed, and a second record information. The substrate 2 on which the corresponding pits and a laser light reflection film 2 for reading information are formed is formed on the corresponding pits.
STP (Surface Transfer Procedures) which transfers the reflective film 2 to the substrate 1 side by peeling the two substrates bonded together with resin facing each other with the reflective films facing each other.
A process called s) is disclosed.

However, as the adhesive used in the present process, the function of the reflective film 1 and the reflective film 2 as an adhesive, and at the same time, the pit shape of the substrate 2 can be held and transferred with high precision, It is obvious that the adhesive composition is the key to the success or failure of this process, as it requires conflicting properties that allow the entire surface to be peeled off smoothly at once without causing physical damage to 2, The optimum material composition for this has not been clarified.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an adhesive composition most suitable for the above-mentioned STP process. That is, the present invention provides an adhesive composition having not only a function as an adhesive, but also a peeling property and an accurate holding / transferring property of unevenness, and also provides an optical disc having good productivity and information recording property. With the goal.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, have found that a cured film having a temperature of 30.degree.
When an ultraviolet-curable composition having a specific elastic modulus in a specific range is used as an adhesive, irregularities on a substrate can be accurately transferred, and the entire surface can be smoothly peeled without damaging the reflective film 2. They found what they could do and led to the present invention.

That is, according to the present invention, an ultraviolet-curable composition is applied onto a substrate having at least pits corresponding to recorded information, and then the ultraviolet-curable composition is cured.
Then, by peeling the cured coating film from the substrate, an ultraviolet-curable composition used for manufacturing an optical disc having a process of transferring pits corresponding to recorded information on the cured coating film, The elastic modulus at 30 ° C is 500
Provided are an ultraviolet-curable composition characterized by being at most MPa, and an optical disk obtained by the composition.

According to the present invention, a substrate 1 on which a translucent reflective film 1 for reflecting a laser beam for reading information is formed on a substrate on which pits corresponding to first recorded information are formed.
And 30 ° C. of the cured coating film provided in contact with the reflective film 1
A cured product of an ultraviolet-curable composition having an elastic modulus of 500 MPa or less, a reflective film 2 provided with a pit corresponding to the second recording information provided so as to be in contact with the cured product, and a substrate; Also provided is an optical disk that includes as an essential.

The ultraviolet-curable composition of the present invention comprises a translucent reflective film 1 for reflecting a laser beam for reading information on a substrate on which pits corresponding to first recorded information are formed.
Is used as an adhesive for bonding the substrate 1 on which the laser light reflecting film 2 for reading information is formed on the substrate 1 on which the pits corresponding to the second recording information are formed, By curing the ultraviolet curable composition and then peeling off the bonded substrate, the composition can be suitably used in a process of transferring the laser light reflecting film 2 to the substrate 1 side.

In the present invention, the reflection film 1 formed on the substrate 1
The reflection film of the cured film is bonded to the reflection film 2 formed on the substrate 2 with a cured product of an ultraviolet curable composition having an elastic modulus at 30 ° C. of 500 MPa or less. Each substrate and each reflective film are selected so that separation occurs at the interface with the reflective film 2.

As the substrate, known and commonly used substrates can be used, and specific examples thereof include thermoplastic synthetic resins. Examples of the substrate include polycarbonate, polymethyl methacrylate, and amorphous polyolefin.

In general, the adhesion of gold and aluminum to polycarbonate is extremely high. Therefore, when polycarbonate is used as one of the substrates, the adhesion between the other substrate and aluminum is higher than that of polycarbonate. It is preferable to select a substrate made of a relatively small thermoplastic synthetic resin.

Here, it is desirable that the substrate 1 is a polycarbonate substrate and the substrate 2 on which the reflection film 2 is formed is a polymethyl methacrylate (PMMA) substrate.

The UV-curable composition preferably has a cured coating film having an elastic modulus at 30 ° C. of 100 MPa or more from the viewpoint of substrate releasability. Above all, 30 of the cured coating
An elastic modulus at 100C in the range of 100 to 500 MPa is particularly preferred.

Further, in order to impart the above properties to the ultraviolet curable composition, 100 parts by weight of the ultraviolet curable composition is
Monofunctional (meth) acrylate is 20 to 45 parts by weight, polyfunctional (meth) acrylate is 5 to 30 parts by weight, and among these polyfunctional (meth) acrylates, three or more functional (meth) acrylates are 15 parts by weight. In order not to exceed, specifically, it is desirable to adjust the amount to be 5 parts by weight or more and less than 15 parts by weight.

The cured coating film has an elastic modulus at 30 ° C. of 500 MPa.
If it exceeds a, the cured film becomes brittle and easily cracked when the bonded substrate is peeled off, making it difficult to peel off the entire reflective film at once, or at the interface between the reflective film and the PMMA substrate when peeling off. 0.1μ, cohesive failure without interfacial delamination
Since a very thin PMMA layer of about m is peeled off while adhering to the reflection film, the signal characteristics read from the reflection film 2 when DVD-18 or DVD-14 is used is undesirably deteriorated.

In preparing the ultraviolet-curable composition of the present invention, an ultraviolet-curable compound and a photopolymerization initiator are used as essential components. As the ultraviolet curable compound, a monofunctional (meth) acrylate or a polyfunctional (meth) acrylate can be used as a polymerizable monomer component. Each of these can be used alone or in combination of two or more. In the present invention, acrylate and methacrylate are collectively referred to as (meth) acrylate, and similarly,
Acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid.

Examples of the polymerizable monomer that can be used in the present invention include the following. Examples of the monofunctional (meth) acrylate include, as a substituent, methyl, ethyl, propyl, butyl, amyl, 2-ethylhexyl,
Octyl, nonyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, nonylphenoxyethyl, tetrahydrofurfuryl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-
Having a group such as 2-hydroxypropyl, dimethylaminoethyl, diethylaminoethyl, nonylphenoxyethyltetrahydrofurfuryl, caprolactone-modified tetrahydrofurfuryl, isobornyl, dicyclopentanyl, dicyclopentenyl, dicyclopentenyloxyethyl, etc. A) acrylate and the like.

Examples of the polyfunctional (meth) acrylate include 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl-acrylate.
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, tricyclodecanedimethanol, ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol ,
Diacrylates such as tripropylene glycol and polypropylene glycol, and tris (2-hydroxyethyl)
Di (meth) acrylate of isocyanurate, di (meth) acrylate of diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol, 2 mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A Of triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of diol di (meth) acrylate obtained by the addition of trimethylolpropane, and 4 moles per 1 mole of bisphenol A. Di (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, trimethylol of diol obtained by adding at least mole of ethylene oxide or propylene oxide Propane tri (meth) acrylate, pentaerythritol tri (meth) acrylate,
Poly (meth) acrylate of dipentaerythritol,
Caprolactone-modified tris [(meth) acryloxyethyl] isocyanurate, alkyl-modified dipentaerythritol poly (meth) acrylate, caprolactone-modified dipentaerythritol poly (meth) acrylate, hydroxypivalate neopentyl glycol diacrylate, caprolactone-modified hydroxy Neopentyl glycol diacrylate pivalate, ethylene oxide-modified phosphoric acid (meth) acrylate, ethylene oxide-modified alkylated phosphoric acid (meth) acrylate, and the like.

Further, N-vinyl-2-pyrrolidone, acryloylmorpholine, vinylimidazole, N-vinylcaprolactam, N-vinylformamide, vinyl acetate, (meth) acrylic acid, (meth) acrylamide,
-Hydroxymethylacrylamide or N-hydroxyethylacrylamide and their alkyl ether compounds can also be used.

Further, those which can be used in combination with the polymerizable monomer include polyester (meth) acrylate, polyether (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate and the like as polymerizable oligomers.

In the present invention, any known and commonly used photopolymerization initiator capable of curing an ultraviolet curable compound represented by a polymerizable monomer and / or a polymerizable oligomer can be used. As the photopolymerization initiator, a molecular cleavage type or a hydrogen abstraction type is suitable for the present invention.

As the photopolymerization initiator used in the present invention, benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, benzyl, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and the like are preferably used. And other molecular-cleaving types such as 1-hydroxycyclohexyl phenyl ketone, benzoyl ethyl ether, benzyldimethyl ketal, 2-hydroxy-2-methyl-1
-Phenyl-propan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- (4-methylthiophenyl) -2-morpholino-propane- 1-one or the like may be used in combination, or benzophenone, 4-phenylbenzophenone, isophthalophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, which is a hydrogen abstraction type photopolymerization initiator, may be used in combination. it can.

Further, sensitizers such as triethylamine, methyldiethanolamine, triethanolamine, p-diethylaminoacetophenone, p-dimethylaminoacetophenone, p-dimethylaminoethyl benzoate, and p-dimethylamino may be used as sensitizers. Amines that do not cause an addition polymerization reaction with the above-mentioned polymerizable components, such as isoamyl benzoate, N, N-dimethylbenzylamine, and 4,4′-bis (diethylamino) benzophenone, can also be used in combination. Of course, it is preferable to select and use the above-mentioned photopolymerization initiator and sensitizer that have excellent solubility in the curable component and do not inhibit the ultraviolet transmittance.

The UV-curable composition may be used at room temperature to 40
It is preferable to use one that is liquid at a temperature of ° C. It is preferable not to use a solvent, and even if it is used, it is preferable to keep it as small as possible. When the composition is applied by a spin coater, the viscosity is 20 to 1000 mPa.
S is preferable, and when it is a relatively thick film, the thickness is preferably adjusted to 100 to 1000 mPa · s.

If necessary, the composition of the present invention may further contain other additives such as a thermal polymerization inhibitor, an antioxidant represented by a hindered phenol, a hindered amine, a phosphite, a plasticizer, and the like. Epoxy silane,
A silane coupling agent typified by mercaptosilane, (meth) acrylsilane and the like can be blended for the purpose of improving various properties. These are selected from those having excellent solubility in the curable component and those that do not impair ultraviolet transmittance.

According to the present invention, a substrate 1 on which a translucent reflective film 1 for reflecting a laser beam for reading information is formed on a substrate on which pits corresponding to first recorded information are formed.
And 30 ° C. of the cured coating film provided in contact with the reflective film 1
Cured product of an ultraviolet curable composition having a modulus of elasticity of 500 MPa or less, a reflective film 2 provided with a pit corresponding to the second recording information provided so as to be in contact therewith, and reflecting a laser beam; By bonding with a substrate, etc.
The final optical disk can be manufactured. These optical disks include at least a substrate as the other substrate or the like.

The optical disk of the present invention can be obtained by any method. For example, it is preferable to manufacture the optical disk obtained by peeling off only the substrate 2 from the previously bonded one.

Examples of the substrate to be bonded to the reflective film 2 include the following. (1) A substrate on which only a reflection film 3 for reflecting a laser beam for reading information is formed on a substrate on which pits corresponding to third recording information are formed. (2) On the substrate on which pits corresponding to the third recorded information are formed, a reflective film 3 for reflecting a laser beam for reading information is formed. A substrate on which a cured product is formed and on which a semi-transparent reflective film 4 for reflecting a laser beam having pits corresponding to fourth recording information provided so as to be in contact with the cured product is formed.

In the present invention, a substrate 1 on which a translucent reflective film 1 for reflecting a laser beam for reading information is formed on a substrate on which pits corresponding to the first recorded information are formed.
And 30 ° C. of the cured coating film provided in contact with the reflective film 1
A cured product of an ultraviolet-curable composition having a modulus of elasticity of 500 MPa or less, a reflecting film 2 provided in contact with the cured product and having a pit corresponding to the second recording information and reflecting a laser beam; The reflection film 2 and the reflection film 3 are opposed to the substrate 1) or (2) or the reflection film 2 and the reflection film 4
DVD or DVD
-14, DVD-18 (sometimes called DVD-17) can be provided.

In this case, the reflection film 1 of the DVD-14
Film 3 and reflection film 2 and reflection film 4 in DVD-18
Is generally the same, including film thickness and material type.

In the optical disk of the present invention, the reflective film and the translucent reflective film are bonded with a cured product of a specific ultraviolet-curable composition. Objects or other adhesives can be used.

[0035]

Next, embodiments of the present invention will be described based on preferred embodiments. First, the reflectivity of the laser light on the unevenness called a pit corresponding to the first recorded information is 18 to
A disc-shaped polycarbonate substrate 1 having a thickness of 0.6 mm on which a translucent reflective film 1 is formed to have a reflectance of 30%, and a laser light reflectance of 45 on irregularities called pits corresponding to the second recorded information. A disk-shaped PMMA substrate 2 having a thickness of 0.6 mm on which a reflective film 2 is formed so as to have a thickness of about 85% is prepared.

Next, two or more polyfunctional (meth) acrylates having two or more (meth) acryloyl groups as a polymerizable monomer or a polymerizable oligomer and a monofunctional (meth) acrylate are used as a photopolymerization initiator. Using a total of 2 to 7 parts by weight of a molecular cleavage type or hydrogen abstraction type per 100 parts by weight of the liquid ultraviolet-curable composition, the ultraviolet-curing type is used so that the elastic modulus at 30 ° C. of the cured coating film is 500 MPa or less. Prepare the composition.

The composition is applied to the reflective film 2 of the substrate 2, and the substrate 1 is bonded so that the film surface of the translucent reflective film 1 faces the film surface of the reflective film 2 coated with the composition. Then, ultraviolet rays are radiated from one or both sides of the bonded disk, and the two are bonded to each other to temporarily form DVD-9. Then, when the substrate is peeled off, the reflection film 2 is transferred to the substrate 1 side. On a substrate 1, a reflective film 1, an intermediate layer made of a cured product of the composition, and a reflective film 2 having irregularities corresponding to the pits of the substrate 2 are sequentially laminated, and formed on one surface of a polycarbonate substrate having a thickness of 0.6 mm. A substrate 3 having two information recording layers is obtained. By bonding two substrates 3, a DVD-
18 are obtained. Also, a substrate 3 having two information recording layers on one side and a substrate having one information recording layer on one side can be bonded together. In this case, a DVD-ROM in which DVD-9 and DVD-5 are bonded together is used. 14 is obtained. DVD-
18 and DVD-14 can be properly used as needed. As the adhesive used for bonding the two substrates 3 or the substrate 3 and a substrate having one information recording layer on one surface, the above-mentioned composition can be used as it is or an ultraviolet curable composition prepared separately. In addition, a hot melt adhesive, a pressure-sensitive adhesive sheet, or the like can be used.

[0038]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Hereinafter, "parts" in the examples means "parts by weight".

Example 1 17 parts of urethane acrylate and 19 parts of 2-hydroxy-3-phenoxypropyl acrylate obtained by reacting 1 mol of polytetramethylene glycol (molecular weight 1000) with 2 mol of isophorone diisocyanate and then reacting with 2 mol of hydroxyethyl acrylate 20 parts of Unidick V-5500 (manufactured by Dainippon Ink and Chemicals, Inc.) as bisphenol A type epoxy acrylate, ethylene oxide-modified trimethylolpropane triacrylate 1
4.5 parts, tripropylene glycol diacrylate 8
Parts, tetrahydrofurfuryl acrylate 15 parts, ethylene oxide-modified phosphate methacrylate 0.2 part, dimethylaminobenzoate 0.3 part, 2,4,6-trimethylbenzoyldiphenylphosphine oxide 2 parts and 1 as a photopolymerization initiator -Hydroxycyclophenyl ketone (4 parts) was mixed and dissolved at 60 ° C for 1 hour to prepare a pale yellow transparent ultraviolet curable composition.

Using this composition, the elastic modulus of the cured coating film, the releasability of the bonded disk,
The pit shape on the reflective film side after peeling was evaluated. The result is first
It is shown in the table.

Example 2 17 parts of urethane acrylate and 22 parts of 2-hydroxy-3-phenoxypropyl acrylate obtained by reacting 1 mol of polytetramethylene glycol (molecular weight: 1000) with 2 mol of isophorone diisocyanate and then reacting with 2 mol of hydroxyethyl acrylate 20 parts of Unidick V-5500 (manufactured by Dainippon Ink and Chemicals, Inc.) as bisphenol A type epoxy acrylate, and ethylene oxide-modified trimethylolpropane triacrylate 9.
5 parts, tripropylene glycol diacrylate 10
Parts, tetrahydrofurfuryl acrylate 15 parts, ethylene oxide-modified phosphate methacrylate 0.2 part, dimethylaminobenzoate 0.3 part, 2,4,6-trimethylbenzoyldiphenylphosphine oxide 2 parts and 1 as a photopolymerization initiator 4 parts of hydroxycyclophenyl ketone were mixed and dissolved at 60 ° C. for 1 hour to prepare a pale yellow transparent ultraviolet-curable composition.

Using this composition, the elastic modulus of the cured coating film, the releasability of the bonded disk,
The pit shape on the reflective film side after peeling was evaluated. The result is first
It is shown in the table.

Example 3 17 parts of urethane acrylate obtained by reacting 1 mol of polytetramethylene glycol (molecular weight: 1000) with 2 mol of isophorone diisocyanate and 2 mol of hydroxyethyl acrylate, 19 parts of ethylene oxide-modified phenol acrylate, bisphenol A type 20 parts of Unidick V-5500 (manufactured by Dainippon Ink and Chemicals, Inc.) as epoxy acrylate, 14.5 ethylene oxide-modified trimethylolpropane triacrylate
Parts, 8 parts of tripropylene glycol diacrylate, 15 parts of tetrahydrofurfuryl acrylate, 0.2 parts of ethylene oxide-modified phosphate methacrylate, 0.3 parts of ethyl dimethylaminobenzoate, 2,4,6-trimethyl as a photopolymerization initiator 2 parts of benzoyldiphenylphosphine oxide and 4 parts of 1-hydroxycyclophenyl ketone were mixed and dissolved at 60 ° C. for 1 hour to prepare a pale yellow transparent ultraviolet-curable composition.

Using this composition, the elastic modulus of the cured coating film, the releasability of the bonded disk,
The pit shape on the reflective film side after peeling was evaluated. The result is first
It is shown in the table.

COMPARATIVE EXAMPLE 1 12 parts of urethane acrylate and 22 parts of 2-hydroxy-3-phenoxypropyl acrylate obtained by reacting 1 mol of polytetramethylene glycol (molecular weight: 1000) with 2 mol of isophorone diisocyanate and then reacting with 2 mol of hydroxyethyl acrylate. 14 parts of Unidick V-5500 (manufactured by Dainippon Ink and Chemicals, Inc.) as a bisphenol A type epoxy acrylate, 13.5 parts of trimethylolpropane triacrylate, 17 parts of tripropylene glycol diacrylate, 15 parts of tetrahydrofurfuryl acrylate 0.2 parts of ethylene oxide-modified phosphoric acid methacrylate, 0.3 parts of dimethylaminobenzoate, 2 parts of 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator And 4 parts of 1-hydroxycyclophenyl ketone at 60 ° C.
The mixture was mixed and dissolved for a period of time to prepare a pale yellow transparent ultraviolet curable composition.

Using this composition, the elastic modulus of the cured coating film, the releasability of the bonded disk,
The pit shape on the reflective film side after peeling was evaluated. The result is first
It is shown in the table.

Comparative Example 2 Unidick V-5500 (manufactured by Dainippon Ink and Chemicals, Inc.) as a bisphenol A type epoxy acrylate
36 parts, ethylene oxide-modified trimethylolpropane triacrylate 14.5 parts, bisphenol A diglycidyl ether diacrylate 20 parts, tripropylene glycol diacrylate 8 parts, tetrahydrofurfuryl acrylate 15 parts, ethylene oxide-modified phosphate methacrylate 0.2 Part, ethyl dimethylaminobenzoate 0.3 part, 2,4,6-trimethylbenzoyldiphenylphosphine oxide 2 parts and 1-hydroxycyclophenyl ketone 4 parts as photopolymerization initiator at 60 ° C.
The mixture was mixed and dissolved for a period of time to prepare a pale yellow transparent ultraviolet curable composition.

Using this composition, the elastic modulus of the cured coating film, the releasability of the laminated disk,
The pit shape on the reflective film side after peeling was evaluated. The result is first
It is shown in the table.

<Test Method 1: Measurement of Elastic Modulus> The ultraviolet curable composition was applied on a glass plate so that the dry coating thickness became 50 to 60 μm, and then a metal halide lamp (with a cold mirror, lamp output 120 W / cm) at 500 mJ / cm ² in a nitrogen atmosphere. The elastic modulus of the cured coating film was measured with an automatic dynamic viscoelasticity meter (Rheovibron DDV-II-EA manufactured by Toyo Baldwin Co., Ltd.), and the dynamic elastic modulus E ′ at 30 ° C. was determined. This E 'was taken as the elastic modulus.

The measurement conditions were a frequency of 3.5 Hz and an amplitude of 1.
6 μm, the temperature rising rate was 3 ° C./min.

<Test Method 2: Peeling Property> The unevenness corresponding to the second recorded information and aluminum as a reflective film on top
The composition was applied to a 0-nm thick polymethyl methacrylate substrate having a thickness of 0.6 mm and a diameter of 12 cm with a dispenser in a circular shape of about 2 g. And a polycarbonate substrate having a thickness of 0.6 mm and a diameter of 12 cm, on which a gold translucent reflective film was formed, was spin-coated with a spin coater so that the thickness of the cured coating film became about 50 to 60 μm. Then, using a belt-conveyor type ultraviolet irradiation apparatus equipped with a 120 W / cm metal halide lamp (eye graphics M03-L31, with a cold mirror) adjusted to a lamp height of 10 cm, in air from the substrate side with the gold translucent film in air. 1
Irradiation was performed at 000 mJ / cm ² to produce a DVD-9 bonded disc. At this time, the irradiation amount of the adhesive that passed through the substrate with the gold translucent film was 500 mJ / cm ² . still,
The UV meter (UVPF-36) manufactured by Eye Graphics Co., Ltd. was used.

Next, a cut was made in the end face of the disk with a cutter, and the two substrates were peeled off, and the peelability was evaluated.

Further, the surface of the aluminum reflective film transferred to the polycarbonate substrate side after peeling was treated with an electron beam three-dimensional roughness analyzer (ERA-800 manufactured by Elionix Inc.).
0FE), and the shapes of the transferred pits were compared.

[0054]

[Table 1] Table 1

The compositions of Examples 1 to 3 have excellent releasability,
The surface of the transferred aluminum reflective film and the shape of the pits are also good.

[0056]

As described above, by using the ultraviolet-curable composition of the present invention, a substrate having two information recording layers on one side can be easily and accurately produced, and a highly reliable DVD-
18 or DVD-14 can be produced efficiently.

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Claims (9)

[Claims] An ultraviolet-curable composition is applied on at least a substrate on which pits corresponding to recorded information have been formed.
An ultraviolet-curable composition used for manufacturing an optical disc having a process of transferring pits corresponding to recorded information on the cured coating film by curing the ultraviolet-curable composition and then peeling the cured coating film from the substrate An ultraviolet curable composition, wherein the cured coating film has an elastic modulus at 30 ° C. of 500 MPa or less. 2. A substrate 1 having a translucent reflective film 1 for reflecting a laser beam for reading information on a substrate on which pits corresponding to first recording information are formed, and a second recording. A substrate 2 on which a laser light reflecting film 2 for reading information is formed on a substrate on which pits corresponding to information are formed.
Are bonded to each other with an ultraviolet-curable composition, the ultraviolet-curable composition is cured, and then the laminated substrate is peeled off, so that it is used in a process of transferring the laser light reflecting film 2 to the substrate 1 side. The ultraviolet-curable composition according to claim 1, wherein 3. The ultraviolet curing according to claim 2, wherein the substrate on which the reflection film is formed is a polycarbonate substrate, and the substrate on which the reflection film is formed is a polymethyl methacrylate (PMMA) substrate. Mold composition. 4. The cured coating film has an elastic modulus at 30 ° C. of 100 MPa.
The ultraviolet-curable composition according to claim 1, wherein the composition is at least a. 5. The ultraviolet-curable composition according to claim 1, wherein the monofunctional (meth) acrylate is prepared in an amount of 20 to 45 parts by weight per 100 parts by weight of the ultraviolet-curable composition. Composition. 6. The ultraviolet-curable composition according to claim 5, wherein the polyfunctional (meth) acrylate is prepared in an amount of 5 to 30 parts by weight based on 100 parts by weight of the ultraviolet-curable composition. 7. The ultraviolet-curable composition according to claim 6, wherein the tri- or higher-functional (meth) acrylate is prepared so as not to exceed 15 parts by weight per 100 parts by weight of the ultraviolet-curable composition. 8. At least claims 1, 2, 3, 4, 5, 6
8. An optical disc, comprising a cured coating film to which pits corresponding to recorded information have been transferred as an intermediate layer, comprising an ultraviolet-curable composition according to any one of items 7 and 7. 9. A substrate 1 having a translucent reflective film 1 for reflecting a laser beam for reading information formed on a substrate on which pits corresponding to first recorded information are formed;
A cured product of an ultraviolet curable composition having an elastic modulus at 30 ° C. of 500 MPa or less and a pit corresponding to the second recording information provided so as to be in contact with the cured coating film provided so as to be in contact therewith are formed. An optical disc including a reflection film 2 for reflecting a laser beam and a substrate as essential components.