JPH1173684A - Resin composition for protective coating and adhesion of dvd - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a reflection film having both of a protective coating function and an adhering function by containing a specified epoxyacrylate and a N= vilnyl lactam compd. into a photosetting component and containing a specified weight range of a photopolymn. initiator. SOLUTION: The photosetting component contains a bifunctional urethane acrylate, epoxyacrylate having a bisphenol-A structure and a N-vinyl lactam compd. expressed by formula I (m is an integer 3 to 5). The photopolymn. initiator contains a benzoylphosphine oxide compd. expressed by formula II by >=0.1 and <=5.0 wt.% to the amt. of the whole photosetting component. In formula II, R<1> , R<2> , R<3> , R<4> , R<5> , R<6> are independently hydrogen, 1 to 4C alkyl, 1 to 4C alkoxy or halogen, X is 1 to 10C alkyl or unsubtd. phenyl or substd. phenyl with substitution of groups selected from 1 to 4C alkyl, 1 to 4C alkoxy and halogen, and n is 0 or 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DVD (digital video disc), which is a kind of optical information recording medium and has a structure in which two substrates made of polycarbonate resin are bonded to each other.
The present invention relates to a photocurable resin composition used as a protective coating agent for a reflective film provided on the surface of at least one of two substrates and an adhesive between the substrates in a sk or digitalversatile disk.

[0002]

2. Description of the Related Art As an optical information recording medium similar to a DVD, a CD (compact disk) is well known. In general, the CD is also provided with a protective coat of a photocurable resin for the purpose of protecting a reflective film formed of an evaporated aluminum film formed on the substrate. In the case of a CD, the substrate is made of a single plate of polycarbonate, and the protective coat is located on the outermost side in terms of structure. Therefore, the resin composition for protective coating is required to have not only a function of protecting the reflective film, but also a function like a hard coat such as being hardly damaged.
As the resin composition, a resin composition having a relatively high crosslinking density of a polymerizable unsaturated group such as an acrylate and a relatively large curing shrinkage, but having a high hardness is used.

On the other hand, unlike a CD, a DVD has a structure in which two thin disk substrates are bonded to each other, and the reflection film is located on a bonding surface of the substrates (an inner surface that is not touched by hands during substrate handling). . An example of such a DVD will be described with reference to FIGS. 3 and 4 showing schematic cross-sectional views. The DVD includes a first disk substrate 1 and a second disk substrate.
Disk substrate 2 is bonded. The disk substrates 1 and 2 are usually made of a polycarbonate resin. A reflective film 3 is provided on the surface of the disk substrate 1 on which pits for recording information are formed. The reflection film 3 is usually formed by vapor deposition of aluminum. A protective coat 5 is formed on the surface of the reflective film 3, and further, the second disk substrate 2
And are stuck together.

FIG. 3 shows a single-sided reading single-layer recording type called "SD-5". No pits are formed on the second disk substrate 2 for recording information. The reflection film 3 provided on the surface of the first disk substrate 1 is disposed so as to face the second disk substrate 2. Then, a protective coat 5 is formed on the surface of the reflective film 3, and is further adhered to the second disk substrate 2 via an adhesive layer 6.

FIG. 4 shows a single-sided reading dual-layer recording type called "SD-9", in which pits for recording information are formed on both of the two disk substrates 1 and 2. I have. A translucent film 4 is provided on the pit surface of one disk substrate 2, and a protective coat 5 is formed thereon similarly to the substrate 1 side. Glued. The translucent film 4 is formed of a vapor-deposited film such as gold. The structure shown in FIG. 4 includes a double-sided recording and double-sided reading type called “SD-10” in which the film 4 on the substrate 2 is also a reflection film.

In the DVD constructed as described above, the CD
The recording density of information is about eight times higher than that of CD, and the track pitch of pits for recording information is about 2 times that of CD.
It is narrowed by a factor of one. This means that the disk substrate 1
Or, if 2 is deformed for some reason, it means that the damage to the pits is large and there is a high possibility that the recorded information cannot be read accurately. From these facts, it is desired that a protective coating agent for a reflective film used in DVDs has a function of hardly shrinking during curing and hardly deforming a disk substrate, rather than a function of hard coating. Become. However, conventionally, a protective coating agent for a CD was generally used as a protective coating agent for a DVD.

[0007]

When a protective coating agent for DVD is used as a protective coating agent for DVD based on a protective coating agent for CD,
In addition to the protective coating agent, an adhesive for bonding the two disk substrates is required. Various materials such as a hot-melt type and a photo-curing type are used as the adhesive. As described above, when the protective coating agent and the adhesive are made of different materials, it is needless to say that the formation of the protective coating and the bonding of the substrates need to be performed in separate steps, which complicates the step of producing a DVD. The problem arises.

An object of the present invention is to provide a DVD having a function of protecting a reflective film formed on a disk substrate and a function of bonding two disk substrates together using one kind of photocurable resin composition. To provide a protective coating and resin composition for bonding.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a photocurable resin composition having such a function. As a result, the following composition can achieve the above object. And found the present invention.

That is, the present invention provides a resin composition for bonding two disk substrates constituting a DVD and protecting a reflective film provided on the surface of at least one of the two substrates. A photocurable component which is cured by a polymerization reaction of an unsaturated group, a photopolymerization initiator and a phenolic primary antioxidant are essential components, and the photocurable component is (i) a bifunctional urethane acrylate, (ii) B) an epoxy acrylate having a bisphenol A skeleton, and (iii) a compound represented by the following formula (I):

[0011]

(Wherein m represents an integer of 3 to 5), wherein the photopolymerization initiator is used in an amount of 0 to the total amount of the photocurable component. 0.1% by weight or more and less than 5.0% by weight of the following formula (II)

[0013]

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶
Each independently represents hydrogen, alkyl having 1 to 4 carbons, alkoxy or halogen having 1 to 4 carbons, and X represents alkyl having 1 to 10 carbons or unsubstituted or 1 to 4 carbons. Represents a phenyl substituted with a group selected from alkyl, alkoxy having 1 to 4 carbon atoms and halogen, and n represents 0 or 1.) ° C
Having a viscosity in the range of 350 to 700 mPa · s.
An object of the present invention is to provide a VD protective coat / adhesive resin composition.

This composition is placed between two disk substrates and light-cured, whereby the two disk substrates are bonded with a cured product of the composition, and a DVD protected with a reflective film is obtained. can get.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Photocurable resin compositions are generally
It contains a photocurable component that is cured by a polymerization reaction of an unsaturated group. Such a photocurable component can be various monomers or oligomers of vinyl polymerization type.

Specific examples of the vinyl polymerizable monomer include:
Vinyl acetates such as vinyl acetate, vinyl propionate and branched fatty acid vinyl, alkyl (meth) acrylate, glycidyl (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylol (Meth) acrylic acid esters such as propane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, styrene, alkylstyrene, divinylbenzene Vinyl-aromatic hydrocarbons, chlorostyrenes, chlorine-containing unsaturated compounds such as chloro (meth) acrylate, N-vinylpyrrolidone, N-vinylcaprolactam, 2-hydroxide Roxy-3-phenoxypropyl acrylate, isobornyl acrylate, dicyclopentenyloxyethyl acrylate and the like can be mentioned.

Specific examples of the vinyl polymerizable oligomer include epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, urethane (meth) acrylate, and silicone (meth) acrylate.

Of these, the composition of the present invention comprises (i)
Bifunctional urethane acrylate, (ii) bisphenol A
Essentially contains at least three components of an epoxy acrylate having a skeleton and (iii) an N-vinyllactam compound represented by the formula (I). Of course, in addition to these three components, one or more of the various photocurable components described above may be contained. The three components essential in the present invention will be described in more detail.

The bifunctional urethane acrylate is generally an oligomer formed by an addition reaction of a diisocyanate, a polyol and a 2-hydroxyalkyl acrylate. The bifunctional urethane acrylate is preferably one in which the urethane group -NHCOO- in the skeleton is not directly bonded to an aromatic ring. When such an aliphatic bifunctional urethane acrylate is used, it is included. Changes over time (particularly yellowing) after the resin composition is hardly occur.
That is, urethane acrylates have recently originated from aromatic diisocyanates, and those in which a urethane group is directly bonded to an aromatic ring are called yellowing types, whereas, from urethane diisocyanates, they have no aromatic rings, or Those having an aromatic ring, to which a urethane group is not directly bonded, are often referred to as non-yellowing type, and the latter is preferable in the present invention. Therefore, the bifunctional urethane acrylate may have an aromatic ring in the molecule, but as described above, a structure in which a urethane group is not directly bonded to the aromatic ring is advantageous. Such an aromatic ring which is not directly bonded to the urethane group is usually brought in from the polyol component.

Therefore, as a preferable diisocyanate which is a raw material of the bifunctional urethane acrylate, an aliphatic diisocyanate such as isophorone diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate and hydrogenated diphenylmethane diisocyanate is exemplified. Preferred polyols include polyethylene glycol, polypropylene glycol, polyether polyols such as polytetramethylene glycol, further polyester polyols, caprolactone modified diols, carbonate diols, polysiloxane polyols, bisphenol A polyether polyols or polyester polyol adducts, and the like. Is exemplified. Examples of the 2-hydroxyalkyl acrylate include 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate.

The weight average molecular weight of the bifunctional urethane acrylate is preferably in the range of 1,000 to 10,000. The content of the bifunctional urethane acrylate is 5 to 75% by weight based on the total amount of the photocurable components contained in the resin composition, that is, based on the total amount of the vinyl polymerizable monomers and oligomers in the composition. %, More preferably 15% by weight or more, and more preferably 60% by weight or less.

The epoxy acrylate having a bisphenol A skeleton has a bisphenol A skeleton and
A monomer or oligomer having a structure in which acrylic acid or methacrylic acid is added to an epoxy group and the epoxy group is opened. Specific examples of epoxy acrylates having a bisphenol A skeleton include those obtained by adding acrylic acid to diglycidyl ether of bisphenol A and those obtained by adding bisphenol A to diglycidyl ether of bisphenol A and adding acrylic acid to the terminal. And the like. The content of the epoxy acrylate having a bisphenol A skeleton is preferably in the range of 1 to 50% by weight, more preferably 5% by weight or more and 30% by weight or less, based on the total amount of the photocurable component.

The N-vinyllactam compound represented by the formula (I) is used as one of monofunctional photopolymerizable monomers. This compound has a relatively high solubility of the polycarbonate resin that is the substrate, and by including this compound in the resin component, improves the adhesion of the coating film to the substrate, thereby improving the resistance of the coating film to environmental tests. Let it. Specific examples of the N-vinyllactam compound represented by the formula (I) include N-vinyl-2-pyrrolidone and N-vinylcaprolactam. This compound is preferably used in an amount of 10 to 40% by weight, more preferably 15% by weight or more and 30% by weight or less, based on the total amount of the photocurable component.

The resin composition of the present invention comprises, as photocurable components, at least three components of the above-described bifunctional urethane acrylate, epoxy acrylate having a bisphenol A skeleton, and an N-vinyl lactam compound represented by the formula (I). Essentially contained, further, as a photopolymerization initiator for photocuring, a benzoylphosphine oxide compound represented by the formula (II), and as an antioxidant,
Contains a phenolic primary antioxidant. By using a bifunctional urethane acrylate and an epoxy acrylate having a bisphenol A skeleton in combination, the shrinkage after curing is reduced, the disk substrate is hardly deformed, and the temporal change after curing is also reduced. Further, by using the benzoylphosphine oxide compound, the adhesive strength to the two disk substrates and the reflective film provided on at least one surface thereof is improved. The use of the phenolic primary antioxidant improves the environmental resistance of the cured product, especially the heat resistance.

In the formula (II) representing a benzoylphosphine oxide compound, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be the same or different from each other;
And alkyl of 1-4, alkoxy having 1-4 carbon atoms or halogen. Here, examples of alkyl include methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
Examples of alkoxy include methoxy, ethoxy, propoxy, and butoxy. Examples of halogen include fluorine, chlorine, and bromine. X is phenyl or carbon number 1 to
Represents an alkyl having 10 carbon atoms, wherein phenyl has 1 to 1 carbon atoms.
It may be substituted with a group selected from alkyl of 4, alkyl having 1 to 4 carbon atoms and halogen. Examples of alkyl, alkoxy and halogen which can be substituted for phenyl include:
The above-mentioned examples of R ^{1 to} R ⁶ are included, and the phenyl represented by X may be substituted with 1 to 3 of these groups. Examples of the alkyl represented by X include methyl, ethyl, propyl, isopropyl, butyl, tert-butyl,
Pentyl, tert-pentyl, hexyl, octyl, 2-
Examples thereof include ethylhexyl, 2,4,4-trimethylpentyl, nonyl, and decyl. As is apparent from these examples, when the number of carbon atoms is 3 or more, the chain may be linear or branched.

As examples of benzoylphosphine oxide-based photopolymerization initiators corresponding to the formula (I) which are currently commercially available, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (sold by BASF) “Lucillin TPO”), bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Irgacure sold by Ciba Specialty Chemicals)
819 "). Further, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide has a weight ratio of 1: 3 with 2-hydroxy-2-methylpropiophenone. “Irgacure” from Ciba Specialty Chemicals in the form of a mixed initiator
1700 "and separately sold by the company as" Irgacure 1800 "in the form of a 1: 3 weight ratio mixed initiator with 1-hydroxycyclohexyl phenyl ketone.

In addition, benzoyldiphenylphosphine oxide, o- or p-toluoyldiphenylphosphine oxide, 4-tert-butylbenzoyldiphenylphosphine oxide, 2,6-dimethylbenzoyldiphenylphosphine oxide, 2,6- Dimethoxybenzoyldiphenylphosphine oxide, 2,
4,6-trimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,6-dibromobenzoyldiphenylphosphine oxide, 2,3,4,6-tetramethylbenzoyldiphenylphosphine oxide, etc. Are also included in the benzoylphosphine oxide compounds of the formula (II).

The benzoylphosphine oxide compound of the formula (I) is used in an amount of
It is contained in the range of 0.1% by weight or more and less than 5% by weight. If the amount is too small, even if another photopolymerization initiator is used in combination, the effect of improving the adhesive strength cannot be sufficiently obtained, and if the amount is too large, the adhesive layer after photocuring changes with time. This tends to make the film opaque (whiten) or cause corrosion of the reflective film. The preferred content of the benzoylphosphine oxide compound of the formula (I) is 1% by weight or more and 4% by weight or less based on the total amount of the photocurable component.

In the present invention, it is essential to use a benzoylphosphine oxide compound of the formula (I) as a photopolymerization initiator, but other photopolymerization initiators may be used in combination. Examples of such a photopolymerization initiator used in combination include benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, diethoxyacetophenone, benzyldimethylketal,
Hydroxy-2-methylpropiophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-
[4- (methylthio) phenyl] -2-morpholinopropan-1-one, dimethylaminoacetophenone, 2,
Compounds having absorption in the ultraviolet region, such as 4-bis (trichloromethyl) -6- (4-methoxyphenyl) -1,3,5-triazine, and visible regions, such as camphorquinone and 3-ketocoumarin. And compounds having absorption. These compounds are each independently represented by the formula (I)
May be used in combination with the benzoylphosphine oxide compound of formula (I), or two or more of them may be used in combination with the benzoylphosphine oxide compound of formula (I). In addition, a sensitizer and the like can be used in combination as needed. Even when a photopolymerization initiator other than the benzoylphosphine oxide compound of the formula (I) is used in combination, the total amount of the photopolymerization initiator is in the range of 0.5 to 20% by weight based on the total amount of the photocurable component. And more preferably 1% by weight or more, and more preferably 10% by weight or less.

Further, the resin composition of the present invention contains, as an essential component, a phenolic primary antioxidant which enhances the environmental resistance (particularly heat resistance) of the cured product and has a small effect of inhibiting the curing reaction by photoradical polymerization. . The phenolic primary antioxidant referred to herein has a phenol skeleton, and has at least one of two o-positions to the phenolic hydroxyl group has an alkyl bonded with a quaternary carbon such as tert-butyl, It is a hindered phenol or one-sided hindered phenol compound that exhibits an antioxidant ability against various resins. Specific examples thereof include 2,6-di-tert.
-Butyl-4-methylphenol, n-octadecyl
3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (6-
tert-butyl-4-methylphenol), 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-
Methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-tert-
Pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate, 4,4'-butylidenebis (2-tert-butyl-5-methylphenol),
4'-thiobis (2-tert-butyl-5-methylphenol), tetrakis [methylene 3- (3,5-di-te
rt-butyl-4-hydroxyphenyl) propionate] methane, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethyl Ethyl] -2, 4, 8,
10-tetrooxaspiro [5.5] undecane and the like. The phenolic primary antioxidant is preferably used in the range of 0.05 to 5% by weight, more preferably 0.01% by weight or more, and
% By weight or less is more preferable.

The resin composition of the present invention may contain, as other additives, fillers such as silica and alumina, and polymers such as polymethyl methacrylate, polyethyl methacrylate, and methyl methacrylate-hydroxyethyl acrylate copolymer. And a flow control agent or leveling agent such as a fluorine-containing compound or a silicon-containing compound, as well as an antioxidant other than the phenolic primary antioxidant, a light stabilizer, and a polymerization inhibitor.

In order to form a uniform coating film having a thickness of about 20 to 60 μm, this resin composition must be adjusted so that its viscosity at 25 ° C. is in the range of 350 to 700 mPa · s. This viscosity is more preferably 400 mPa · s or more and 650 mPa · s or less. In particular, when forming a uniform coating film by spin coating, it is very important to control the viscosity of the resin liquid. If the viscosity is too low, a predetermined film thickness cannot be reached, and if the viscosity is too high, problems such as entrapment of bubbles in the resin will occur. When the viscosity of the resin liquid is high, it is of course possible to increase the usable viscosity range by raising the temperature of the resin liquid to lower the viscosity. Problems such as acceleration of aging and an increase in the amount of polycarbonate used as a substrate occur.

Next, the usage of the resin composition of the present invention and a specific example of a DVD obtained by using the resin composition will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view of a DVD showing an example in which the resin composition of the present invention is applied to a single-sided reading single-layer recording type SD-5 corresponding to the structure of FIG. . Pits for recording information are formed on a first disk substrate 1 made of a polycarbonate resin, and the pit surfaces are covered with a reflective film 3. This reflection film 3 is usually formed by vapor deposition of aluminum. A second disk substrate 2 made of a polycarbonate resin is opposed to the pit surface of the first substrate 1, and a protective coating / adhesive layer 7 is provided between the reflective film 3 on the substrate 1 and the substrate 2. Is provided.

FIG. 2 shows a single-sided readout of the resin composition of the present invention corresponding to the structure of FIG.
It is a schematic sectional drawing of DVD which shows the example applied to SD-9 of a layer recording type. In this example, two disk substrates 1
The pits on the disk substrate 1 are covered with a reflective film 3 and the pit surfaces on the disk substrate 2 are covered with a translucent film 4.
The reflective film 3 is usually formed by vapor deposition of aluminum, and the translucent film 4 is formed by vapor deposition of gold or the like. The pit surfaces of the disk substrates 1 and 2 face each other on the inner side, and the protective coat / adhesive layer 7 is provided there.

The resin composition of the present invention is used as the protective coat / adhesive layer 7 in FIGS. 1 and 2. The protective coat / adhesive layer 7 can be formed, for example, as follows. First, the disk substrate 1
And one of the two substrates (the substrate 1 on which the reflective film 3 is provided).
In the case of (1), the above resin composition is uniformly applied on the reflective film 3 and on the substrate 2 provided with the translucent film 4) by a spin coating method or the like. The other disk substrate is uniformly coated with a protective coat / adhesive layer 7 made of the resin composition having a thickness of 20 to 60 μm.
Glue so that it becomes m. Alternatively, the resin composition is poured between two disk substrates 1 and 2,
By rotating and spin coating the disk substrates 1 and 2 in this state, the resin composition is spread out, and the thickness of the protective coat / adhesive layer 7 made of the resin composition is uniformly 20 to 60 μm. You may do so.

In the case of the single-sided reading single-layer recording type as shown in FIG. 1, a predetermined amount of light is irradiated from the side of the second disk substrate 2 which is not provided with a pit and a reflective film for recording information, and is protected. The resin composition forming the coat / adhesive layer 7 is cured. On the other hand, as shown in FIG.
In the case of a layer recording type, the second
Is irradiated from the disk substrate 2 side to cure the resin composition forming the protective coat / adhesive layer 7. Although not shown, a double-sided recording and double-sided reading type DVD
, The resin composition of the present invention can be applied. In this case, a reflection film is provided on each of the opposing surfaces of the two disk substrates. However, even though the reflection film is used, a small amount of light is transmitted, so that light is relatively easily transmitted through at least one of the reflection films. By applying or using strong light, the resin composition of the present invention is applied,
The protective coat / adhesive layer can be formed by the method described above.

[0038]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, the viscosity was measured using a B-type viscometer, rotor N
Using o.2, measured at 25 ° C and 30 rpm. In the following examples, the following components (all of which are commercially available and indicated by trade names) were used as components constituting the composition.

(A) Photo-curable component (A1) Bifunctional urethane acrylate EBECRYL 270 (manufactured by Daicel UCB): aliphatic polyether polyol type bifunctional urethane acrylate UX-6101 having no aromatic ring (Nippon Kagaku) Non-yellowing polyester polyol type bifunctional urethane acrylate UX-4101 (manufactured by Nippon Kayaku) having a benzene ring but having a benzene ring, but a urethane group is not directly bonded to the benzene ring. A non-yellowing polyester polyol type bifunctional urethane acrylate Aronix M-1310 (manufactured by Toagosei Co., Ltd.) in which a urethane group is not directly bonded to its benzene ring: has a benzene ring, and the urethane group is directly bonded to its benzene ring Yellowing type polyester polyol type bifunctional urethane acrylate UX-2301 (Yakusha): a bifunctional urethane acrylate of a yellowing type polyether polyol type having a benzene ring and a urethane group directly bonded to the benzene ring

(A2) Epoxy acrylate having a bisphenol A skeleton Lipoxy SP-1519 (manufactured by Showa Polymer): bisphenol A diglycidyl ether diacrylate

(A3) Other monofunctional photopolymerizable monomer NV-2P / RC (manufactured by ISP Investment): N-vinyl-2-pyrrolidone V-Cap / RC (manufactured by ISP Investment): N-vinylcaprolactam biscoat 150 (manufactured by Osaka Organic Chemicals): tetrahydrofurfuryl acrylate Aronix M-5700 (manufactured by Toagosei): 2-hydroxy-3-phenoxypropyl acrylate QM-589 (manufactured by Rohm and Haas): isobornyl acrylate FA-513A (manufactured by Hitachi Chemical): tricyclodecane acrylate HO (manufactured by Kyoeisha Chemical): 2-hydroxyethyl methacrylate MANDA (manufactured by Nippon Kayaku): neopentyl glycol diacrylate hydroxypivalate

(B) Photopolymerization initiator (B1) Benzoylphosphine oxide compound of formula (I) Lucirin TPO (manufactured by BASF): 2,4,6-trimethylbenzoyldiphenylphosphine oxide Irgacure 1800 (Ciba Specialty Co., Ltd.) Chemicals): bis (2,6-dimethoxybenzoyl)
Mixture of (2,4,4-trimethylpentyl) phosphine oxide and 1-hydroxycyclohexylphenyl ketone in a weight ratio of 1: 3

(B2) Other photopolymerization initiator Irgacure 184 (manufactured by Ciba Specialty Chemicals): 1-hydroxycyclohexyl phenyl ketone Irgacure 907 (manufactured by Ciba Specialty Chemicals): 2-methyl-1- [4 -(Methylthio) phenyl] -2-morpholinopropan-1-one

(C) Phenolic primary antioxidant Sumilizer BHT (manufactured by Sumitomo Chemical Co., Ltd.): 2,6-di-tert
-Butyl-4-methylphenol

Examples 1 to 4 and Comparative Examples 1 to 6 <Preparation of Samples for Evaluation>
A resin composition is uniformly applied between two substrates by dripping on a 0.6 mm thick polycarbonate substrate for VD, spinning another substrate on top of it, and spinning it. Spread out. The rotation speed of the spin coating was adjusted so that the cured film thickness of the composition sandwiched between the substrates at a resin temperature of about 25 ° C. was about 40 μm. The 0.6 mm thick polycarbonate substrate for DVD used here has a diameter of 1 mm.
One disk is a 2 cm disk, on which a signal is recorded and an aluminum vapor-deposited film is formed, and the other is a dummy with no signal recording and no aluminum vapor-deposited film. A sample in which the resin composition was uniformly coated between two substrates was irradiated with ultraviolet rays of about 300 mJ / cm ² from the dummy polycarbonate substrate side using a high-pressure mercury lamp to cure the resin composition.

[0046]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example No. implementation example comparisons Example 1 2 3 4 1 2 3 4 5 6 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Resin composition (parts by weight ) (A1) EBECRYL 270 41.0 45.0 − − 41.0 41.0 41.0 − 45.0 50.0 UX-6101 − − 36.2 31.9 − − − − − − ARONIX M-1310 − − − − − − − 41.0 − − ─────── ────────────────────────── (A2) Rifoxy SP-1519 20.8 7.9 12.2 17.5 20.8 20.8 20.8 20.8 7.9 − ─────── ────────────────────────── (A3) NV-2P / RC 19.1 23.5 − − 19.1 19.1 − 19.1 23.5 25.0 V-Cap / RC − − 25.8 25.3 − − − − − − Pulse coat 150 19.1 − 25.8 25.3 19.1 19.1 38.2 19.1 − − Aronix M-570 0 − 15.7 − − − − − − 15.7 16.7 QM-589 − 7.9 − − − − − − 7.9 8.3 ────────────────────────── ─────── (B1) Lucirin TPO 2.5 1.0 2.5 2.5 5.0 − 2.5 2.5 − 1.0 ル───── (B2) Dolphin cure 184 2.5 1.0 2.5 2.5 5.0 2.5 2.5 2.5 2.5 1.0 Dolphin cure 907 − − − − − 1.0 − − 1.0 − ────────────────── ─────────────── (C) Sumilizer BHT 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 ────────────────────粘度 Viscosity at 25 ° C (mPas) 500 530 480 490 530 560 520 950 610 410 ━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━━━━

<Evaluation of Sample> First, since a coating film was formed by spin coating, it was determined according to the following criteria whether or not a predetermined film thickness could be obtained within the usable condition range of the apparatus. ○ A film thickness of 40 μm can be obtained by adjusting the use conditions of the apparatus. × A film thickness of 40 μm cannot be obtained even when the operating conditions of the apparatus are adjusted.

Further, whether or not bubbles were trapped in the obtained coating film was visually observed and evaluated according to the following criteria. ○ No air bubbles are found. B: Occasionally, bubbles were observed in a plurality of tests. × Air bubbles are always observed.

The resin composition for DVD has a high adhesive strength to a polycarbonate or aluminum vapor-deposited film after curing, a low curing shrinkage that hardly causes the substrate to warp, an appropriate Young's modulus characteristic, a glass transition temperature, a low water absorption, and the like. It is required to exhibit the physical properties of. In addition, these physical properties can be measured, for example, at a temperature of 8
It is also required to maintain the temperature after a 96-hour environmental test at 0 ° C. and a relative humidity of 85%. Therefore, here, as a method for simply and rationally evaluating these various physical properties, an environmental test method at a temperature of 105 ° C. and a relative humidity of 100% for 48 hours was adopted. Those having no appearance defect such as peeling or warping after the environmental test were performed at a temperature of 80 ° C and a relative humidity of 8 ° C.
It is considered that no problem occurs similarly in an environmental test at 5% for 96 hours.

A specific test method is as follows. A sample prepared as described above is placed in a pressure cooker operated at a temperature of 105 ° C. and a relative humidity of 100% and held for 48 hours. Thereafter, the sample is taken out, and it is visually determined whether or not there is any change in appearance such as peeling of the substrates, opacity (whitening) of the adhesive layer, yellowing of the adhesive layer, corrosion of the aluminum deposited film, and warping of the substrate. Thereafter, a knife is lightly applied to the resin layer between the substrates to try to peel the substrates from each other, and it is confirmed whether or not a sufficient adhesion force can be maintained. In addition, as the resin composition used in this test, a resin composition showing sufficient adhesion to both polycarbonate and an aluminum vapor-deposited film before the test was selected in both the examples and the comparative examples.

<Results> Table 2 summarizes the evaluation results of each composition. It was found that the compositions of Examples 1, 3 and 4 not only had a function as an adhesive but also had a sufficient function as a protective coating agent for a reflective film (aluminum vapor-deposited film). In the composition of Example 2, although the separation between the substrates was not recognized, the adhesion was slightly low, but the other performance was good. By increasing the amount of photopolymerization initiator with this composition,
Alternatively, if another photopolymerization initiator such as Irgacure 907 is used in some cases, the adhesion is further improved.

On the other hand, each composition of the comparative example causes poor appearance such as poor suitability for spin coating, peeling of the substrates, opacity or yellowing of the adhesive layer, and corrosion of the aluminum deposited film.
The balance between the function as an adhesive and the function as a protective film of a reflective film (aluminum-deposited film) was not satisfactory.

[0053]

[Table 2] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example No. implementation example comparisons Example 1 2 3 4 1 2 3 4 5 6 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Suitable for spin coating Adjustment characteristics (40 μm) ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Bubble removal ○ ○ ○ ○ ○ ○ ○ × ○ ○ ──────────────────────評 価 Evaluation results after environmental test Peeling between boards No No No No No No No Yes Yes No Yes Yes Opaque of adhesive layer No No No No No No No No Yes Yes Yes Yellowing of the adhesive layer No No No No No No No No Yes No No Corrosion of the aluminum deposition film No No No No No Yes No No No Yes No No Board warping No N / A N / A N / A N / A N / A N / A N / A Adhesion strength between substrates Maintain Maintain Maintain Maintain Lower Decrease Peel Peel Decrease Peel ─────────── Overall judgment ◎ ○ ◎ ◎ × × × × × × ━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━━━

Each of the compositions of the examples has good adhesion to a polycarbonate substrate provided with a gold vapor-deposited film, and can be photocured when applied between polycarbonate substrates provided with a double-sided aluminum vapor-deposited film. . Therefore, the composition of the present invention can be sufficiently used for SD-9 and SD-10.

Comparative Examples 7 to 10 Two polycarbonate substrates were prepared in the same manner as in Example 1 by using each of the resin compositions shown in Table 3 (all containing no phenolic primary antioxidant). Spin coating was performed in between, and the film thickness adjustment characteristics and bubble elimination property during spin coating were evaluated. Table 3 also shows the results.

[0056]

[Table 3]

As can be seen from Table 3, in Comparative Examples 7 to 9, bubbles were not sufficiently removed during spin coating. On the other hand, Comparative Example 10 is excellent in spin coating properties including film thickness adjusting properties and air bubble releasability, but has a large amount of phosphine oxide-based photopolymerization initiator lucilin TPO, Considering the results of Comparative Example 1 and the like, it is assumed that corrosion of the aluminum deposited film is likely to occur.

Reference Examples 1 and 2 Examples of how heat resistance changes depending on the presence or absence of a phenolic primary antioxidant are shown below. Each of the resin compositions shown in Table 4 was spin-coated between two polycarbonate substrate plates in the same manner as in Example 1 to evaluate the film thickness adjustment characteristics and air bubble removal during spin coating. In both compositions, the film thickness control characteristics of 40 μm and the bubble-removing property were good. Further, when the obtained polycarbonate bonded substrate was held in boiling water, the substrate of Reference Example 1 was peeled off by boiling for 16 hours, whereas the substrate of Reference Example 2 was still two substrates after boiling for 40 hours. The adhesive force was maintained without peeling. In this example, although a phosphine oxide-based photopolymerization initiator was not added, improvement in heat resistance was confirmed by the presence of the phenol-based primary antioxidant.

[0059]

[Table 4]

[0060]

By applying the resin composition of the present invention to the production of a DVD, formation of a protective coat and bonding of two substrates can be performed simultaneously, and the obtained DVD has
It has excellent resistance to environmental tests and excellent adhesion between substrates.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example in which the resin composition of the present invention is applied to a single-sided reading single-layer recording type DVD.

FIG. 2 is a schematic sectional view showing an example in which the resin composition of the present invention is applied to a single-sided reading dual-layer recording type DVD.

FIG. 3 is a schematic sectional view showing a conventional example of a single-sided reading single-layer recording type DVD.

FIG. 4 is a schematic sectional view showing a conventional example of a single-sided reading dual-layer recording type DVD.

[Explanation of symbols]

 1, 2, disk substrate, 3 reflective film, 4 translucent film, 7 protective coating / adhesive layer.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 20, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 8

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claim 9

[Correction method] Change

[Correction contents]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

Examples of benzoylphosphine oxide-based photopolymerization initiators corresponding to the formula (II) which are currently commercially available include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (available from BASF). “Lucillin TPO”), bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Irgacure sold by Ciba Specialty Chemicals)
819 "). Further, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide has a weight ratio of 1: 3 with 2-hydroxy-2-methylpropiophenone. “Irgacure” from Ciba Specialty Chemicals in the form of a mixed initiator
1700 "and separately sold by the company as" Irgacure 1800 "in the form of a 1: 3 weight ratio mixed initiator with 1-hydroxycyclohexyl phenyl ketone.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

The benzoylphosphine oxide compound of the formula (II) is used in an amount of
It is contained in the range of 0.1% by weight or more and less than 5% by weight. If the amount is too small, even if another photopolymerization initiator is used in combination, the effect of improving the adhesive strength cannot be sufficiently obtained, and if the amount is too large, the adhesive layer after photocuring changes with time. This tends to make the film opaque (whiten) or cause corrosion of the reflective film. The preferred content of the benzoylphosphine oxide compound of the formula (II) is 1% by weight or more and 4% by weight or less based on the total amount of the photocurable component.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

In the present invention, it is essential to use a benzoylphosphine oxide compound of the formula (II) as a photopolymerization initiator, but other photopolymerization initiators may be used in combination. Examples of such a photopolymerization initiator used in combination include benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, diethoxyacetophenone, benzyldimethylketal,
Hydroxy-2-methylpropiophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-
[4- (methylthio) phenyl] -2-morpholinopropan-1-one, dimethylaminoacetophenone, 2,
Compounds having absorption in the ultraviolet region, such as 4-bis (trichloromethyl) -6- (4-methoxyphenyl) -1,3,5-triazine, and visible regions, such as camphorquinone and 3-ketocoumarin. And compounds having absorption. These compounds are each independently represented by the formula (II)
May be used in combination with the benzoylphosphine oxide compound of formula (II), or two or more of them may be used in combination with the benzoylphosphine oxide compound of formula (II). In addition, a sensitizer and the like can be used in combination as needed. Even when a photopolymerization initiator other than the benzoylphosphine oxide compound of the formula (II) is used in combination, the total amount of the photopolymerization initiator is in the range of 0.5 to 20% by weight based on the total amount of the photocurable component. And more preferably 1% by weight or more, and more preferably 10% by weight or less.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

Further, the resin composition of the present invention contains, as an essential component, a phenolic primary antioxidant which enhances the environmental resistance (particularly heat resistance) of the cured product and has a small effect of inhibiting the curing reaction by photoradical polymerization. . The phenolic primary antioxidant referred to herein has a phenol skeleton, and has at least one of two o-positions to the phenolic hydroxyl group has an alkyl bonded with a quaternary carbon such as tert-butyl, It is a hindered phenol or one-sided hindered phenol compound that exhibits an antioxidant ability against various resins. Specific examples thereof include 2,6-di-tert.
-Butyl-4-methylphenol, n-octadecyl
3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (6-
tert-butyl-4-methylphenol), 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-
Methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-tert-
Pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate, 4,4'-butylidenebis (2-tert-butyl-5-methylphenol),
4'-thiobis (2-tert-butyl-5-methylphenol), tetrakis [methylene 3- (3,5-di-te
rt-butyl-4-hydroxyphenyl) propionate] methane, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethyl Ethyl] -2, 4, 8,
10-tetraoxaspiro [5.5] undecane and the like. The phenolic primary antioxidant is preferably used in the range of 0.05 to 5% by weight, more preferably 0.01% by weight or more, and
% By weight or less is more preferable.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction contents]

(B) Photopolymerization initiator (B1) Benzoylphosphine oxide compound of formula (II) Lucirin TPO (manufactured by BASF): 2,4,6-trimethylbenzoyldiphenylphosphine oxide Irgacure 1800 (Ciba Specialty Co., Ltd.) Chemicals): bis (2,6-dimethoxybenzoyl)
Mixture of (2,4,4-trimethylpentyl) phosphine oxide and 1-hydroxycyclohexylphenyl ketone in a weight ratio of 1: 3

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0058

[Correction method] Change

[Correction contents]

Reference Examples 1 and 2 Examples of how heat resistance changes depending on the presence or absence of a phenolic primary antioxidant are shown below. Using each of the resin compositions shown in Table 4, spin coating was performed between two polycarbonate substrates in the same manner as in Example 1, and the film thickness adjustment characteristics and bubble elimination properties during spin coating were evaluated. In both compositions, the film thickness adjusting property of 40 μm and the bubble-removing property were good. Further, when the obtained polycarbonate bonded substrate was held in boiling water, the substrate of Reference Example 1 was peeled off by boiling for 16 hours, whereas the substrate of Reference Example 2 was still two substrates after boiling for 40 hours. The adhesive force was maintained without peeling. In this example, although a phosphine oxide-based photopolymerization initiator was not added, improvement in heat resistance was confirmed by the presence of the phenol-based primary antioxidant.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09J 163/10 C09J 163/10 175/16 175/16

Claims (10)

[Claims] 1. A resin composition for bonding two disk substrates constituting a DVD and protecting a reflective film provided on a surface of at least one of the two substrates, A photocurable component which is cured by a polymerization reaction of an unsaturated group, a photopolymerization initiator and a phenolic primary antioxidant as essential components, and the photocurable component is a bifunctional urethane acrylate, an epoxy acrylate having a bisphenol A skeleton, And the following formula (I) (Wherein m represents an integer of 3 to 5), wherein the photopolymerization initiator is 0.1% by weight or more based on the total amount of the photocurable component. Formula (II) of an amount less than 5.0% by weight (Wherein, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ independently represent hydrogen, alkyl having 1 to 4 carbons, alkoxy or halogen having 1 to 4 carbons, and X is Represents alkyl having 1 to 10 carbons or unsubstituted or phenyl substituted with a group selected from alkyl having 1 to 4 carbons, alkoxy having 1 to 4 carbons and halogen, and n represents 0 or 1. A benzoylphosphine oxide compound represented by the following formula:
D in the range of 50 to 700 mPa · s.
VD protective coating / adhesive resin composition. 2. The composition according to claim 1, wherein the urethane group in the skeleton of the bifunctional urethane acrylate is not directly bonded to an aromatic ring. 3. The composition according to claim 1, wherein the bifunctional urethane acrylate is present in a range of 5 to 75% by weight based on the total amount of the photocurable component. 4. An epoxy acrylate having a bisphenol A skeleton in an amount of 1 to 50 based on the total amount of the photocurable component.
A composition according to any of the preceding claims, being present in the range of weight percent. 5. The composition according to claim 1, wherein the N-vinyl lactam compound is N-vinyl-2-pyrrolidone. 6. The composition according to claim 1, wherein the N-vinyl lactam compound is N-vinyl caprolactam. 7. The composition according to claim 1, wherein the N-vinyl lactam compound is present in an amount of 10 to 40% by weight based on the total amount of the photocurable component. 8. The composition according to claim 1, wherein the benzoinphosphine oxide compound is 2,4,6-trimethylbenzoyldiphenylphosphine oxide. 9. The photopolymerization initiator contains a compound other than the benzoylphosphine oxide compound represented by the formula (I), and the total amount of these photopolymerization initiators is 0 to the total amount of the photocurable component. 9. The composition of claim 1, wherein the content is in the range of 0.5 to 20% by weight.
The composition according to any one of the above. 10. The composition according to claim 1, wherein the phenolic primary antioxidant is present in a range of 0.05 to 5% by weight based on the total amount of the photocurable component.