JPS62177015A - Disc for optically recording information - Google Patents

Abstract

PURPOSE:To obtain the titled readily formable disc outstanding in optical isotropy, free from developing torsion or warpage under highly humid conditions, by providing a recording layer on one side of a base made by forming a composition comprising epoxy compound, carboxyl group-contg. photopolymerizable compound and photo-initiator. CONSTITUTION:A composition comprising (A) a compound having at least two epoxy groups (e.g. bisphenol A glycidyl ether), (B) a carboxyl group-contg. photopolymerizable compound [e.g. a compound of formula (R is H or methyl; R2 and R3 are each aliphatic, aromatic or alicyclic residue; A is ester bond; m and n are each 1-3)] and, if needed, (c) another photopolymerizable compound analogous to the component B [e.g. methyl (meth)acrylate], (D) a photo- initiator, and (E) a curing accelerator is normally irradiated with active rays followed by heating to complete the curing to form a base. One side of said base is provided with a recording layer to obtain the objective disc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical information recording disc. More specifically, the present invention relates to obtaining an optical information recording disk for reading information recorded with a laser beam by molding a curable resin composition.

(Relationship with conventional technology) The method of reading minute recorded information on a disk by reflecting a spot beam of a laser beam can significantly increase the recording density, and it provides excellent image and sound quality characteristics, making it possible to read images and sound. Its use in applications such as sound reproduction has rapidly increased.

The disks used in this recording/reproducing system are required not only to be transparent but also to have optical isotropy (non-optical rotation), since laser beams pass through the disk substrate. Thermoplastic resin is usually used as the resin for the disk substrate, but it is known that the flow of the resin during molding causes molecular orientation and loss of optical isotropy. Anisotropy is a fatal defect for optical information recording disk substrates. Therefore, at present, only polycarbonate and polymethyl methacrylate are practically used as optical information recording disks.

(Problems to be Solved by the Invention) However, disks using polycarbonate as a substrate have poor optical isotropy and have low surface hardness, making them easily damaged. On the other hand, disks using polymethyl methacrylate as a substrate have a problem in that they warp or twist, especially when placed in humid conditions.

In addition, both polycarbonate substrates and polymethyl methacrylate substrates have high molding temperatures of 200°C or higher.
At the same time, if the substrate is not sufficiently dried before molding, air bubbles may be generated inside the substrate, and the recording material layer cannot be protected from chemical changes, resulting in problems such as a short life span as a disk substrate.

(Means for Solving the Problems) Therefore, the present inventors have developed a material that can be easily molded by a casting method, has excellent optical isotropy, and does not warp or twist under high humidity conditions. As a result of intensive research to obtain an optical information recording disc with excellent surface hardness,
By using a curable resin composition containing an epoxy compound, a photopolymerizable compound having a carboxyl group in the molecule, a photoinitiator, and a curing accelerator, the above-mentioned problems can be solved at once. We have discovered that this is the case, and have arrived at the present invention.

That is, the present invention is an optical information recording disk characterized in that a recording layer is formed on one side of a flat plate formed by molding the following composition.

Compound (A) having two or more epoxy groups in the molecule,
A photopolymerizable compound (B) having one or more carboxyl groups in the molecule, a mixture of the compound (B) and another photopolymerizable compound (C), a photoinitiator (D), and a curing accelerator This is a curable resin composition consisting of (E).

The optical information recording disk referred to in the present invention includes read-only type, additional recording (DRAW) type, and rewritable type, and its features are: ■ large capacity, ■ non-contact recording and reproduction, ■ Trick plays such as still images and high-speed random access are possible, and specifically, optical video discs (VDs), which are playback-only optical discs, and audio PCs.
Examples include lightweight, high-quality optical compact discs (CDs) that record M signals, DRAW discs, rewritable discs that utilize crystal phase transition, and magneto-optical discs.

The recording layer referred to in the present invention is: 1. A reflective layer of a metal thin film mainly made of aluminum, which is formed on the information surface of the disk substrate after molding by vacuum deposition, ion sputtering, etc.
1) TeOx, Ge-Te-As, used in rewritable disks that utilize the crystal-amorphous phase transition caused by temperature rise due to laser beam irradiation, 5
e-Te, 5n-Te-8e, As-8e -8-
Amorphous semiconductors such as Ge, ii+) Tb-Fe-Co used in magneto-optical disks that perform recording by reversing the magnetism in the direction of the magnetic field only in the temperature-rising part by applying a magnetic field at the same time as the temperature rises due to laser light irradiation. , Co-T
amorphous metal magnetic film such as b-Fe, Mn-Cu-
Examples include a B1 polycrystalline film and a cobalt ferrite oxide magnetic film.

The epoxy compound (A) having at least two epoxy groups in the molecule used in the present invention refers to an epoxy compound (A) having an epoxy equivalent of 1
00-4000. Preferably it is 100-1000.

Typical compounds include bisphenol-type epoxy resins, which are diglycidyl ethers such as bisphenol A, bisphenol F, and halogenated bisphenol A, and novolac-type epoxy resins, which are polyglycidyl ethers such as phenol novolak and cresol novolac. Polyglycidyl ethers of dihydric or higher polyhydric phenols, ethylene glycol, propylene glycol, neopentyl glycol, L4 7"tanediol, 1,6-hexane'diol, trimethylolpropane, etc. Examples include polyglycidyl ethers of alcohols.These epoxy compounds can be used alone or in combination of two or more.

An epoxy compound having one epoxy group in the molecule, such as allyl glycidyl ether, phenyl glycidyl ether, etc., can also be used in combination.

Among these epoxy compounds having at least two epoxy groups in the molecule, preferred epoxy compounds include bisphenol A type epoxy compounds, phenol novolak type polyepoxy compounds, and cresol novolak type polyepoxy compounds.

Examples of the photopolymerizable compound (B) having one or more carboxyl groups in the molecule used in the present invention include (1)
Acrylic acid, methacrylic acid, itaconic acid, crotonic acid,
Unsaturated carboxylic acid compounds such as fumaric acid and (11)
There is a compound represented by the following general formula (II).

(CH2-C-COO piece R2±A÷familiar-(-COOH)
. ...(II) (in the formula, R, U represents hydrogen or a methyl group, R2 and avian each represent an aliphatic, aromatic, or ring group residue, represent an AH ester bond, m and ni each represent 1 Indicates a positive integer of ~3.) In the general formula (I[), R2 is preferably a divalent to tetravalent hydrocarbon group having 2 to 10 carbon atoms or a hydroxyl group-containing hydrocarbon group. , R3ho number of carbon atoms 2~
10, a di- to tetravalent aliphatic polybasic acid residue having 6 to 15 carbon atoms, or a di- to 4-valent aromatic polybasic acid residue having 6 to 10 carbon atoms. It is preferable that it is a ring group polybasic acid residue.

Examples of the compound represented by the general formula (n) include the following compounds.

Examples of compounds where m=1 and n=1 include succinic acid mono(meth)acryloyloxyethyl ester (acryloyloxyethyl ester and methacryloyloxyethyl ester).

The same abbreviations are given below. ), phthalic acid mono(meth)acryloyloxyethyl ester, maleic acid mono(meth)
Acryloyloxyethyl ester, tetrahydrophthalic acid mono(meth)acryloyloxyethyl ester, hexahydrophthalic acid mono(meth)acryloyloxyethyl ester, endo-bicyclo(2.2.1)
-5-hebutene-2,3-dicarboxylic acid mono(meth)acryloyloxyethyl ester, tetrahydrophthalic acid mono-2-(meth)acryloyloxy-1=(phenoxymethyl)ethyl ester, phthalic acid mono-2-
Examples include hydroxy-3-(meth)acryloyloxypropyl ester, succinic acid mono 2=hydroxy-3-(meth)acryloyloxypropyl ester, and the like.

Examples of the compound where m=1 and n=2 include trimellitic acid mono-2-(meth)acryloyloxyethyl ester. m=1. Examples of the compound where n=3 include pyromellitic acid mono-2-(meth)acryloyloxyethyl ester.

Examples of compounds where m=2 and n=1 include phthalic acid mono-(2,3-bis(meth)acryloyloxyinpropyl) ester, methyltetrahydrophthalic acid mono-(2,3-bis(meth) acryloyloxyisopropyl] ester, tetrahydrophthalic acid mono-(2,
Examples thereof include 3-bis(meth)acryloyloxyisopropyl] ester and succinic acid mono-[2,3-bis(meth)acryloyloxyinpropyl]ester.

Examples of compounds where m=2 and n=2 include trimellitic acid mono-[4,5-bis(meth)acrylate is royloxyneopentyl] ester, trimellitic acid mono-(3,4-bis(meth)acrylate) ) acryloyl 7′′ oxyisobutyl] ester.

Examples of the compound where m=3 and n-2 include trimellitic acid mono-(3,4,5-)lis(meth)amacryloyloxyneopentyl] ester.

An example of the compound where m=3 and n=3 is pyromellitic acid mono-(3,4,5-tris(meth)amacryloyloxyneopentyl)esternato.

Among the above-mentioned compounds, as the photopolymerizable compound (B),
Particularly preferred is (11). These photopolymerizable compounds (B) having a carboxyl group in the molecule can be used alone or in combination of two or more, or in combination with one or more of the other photopolymerizable compounds (C) described below. used.

The amount of the photopolymerizable compound (B) containing one or more carboxyl groups in the molecule in the photopolymerizable compound (B+C) used in the present invention is 10 to 100% by weight. It is a photopolymerizable compound having one or more photopolymerizable double bonds in situ, the amount of which is less than 10% by weight.

Examples of photopolymerizable compounds having one photopolymerizable double bond in the molecule include (1) methyl (meth)acrylate, ethyl (meth)acrylate, n- and i-
Alkyl (meth)acrylates such as propyl (meth)acrylate, n-1see- and mo-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate Hydroxyalkylene glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyoxyalkylene glycol mono(meth)acrylates such as tetrahydrofurfuryl(meth)acrylate, etc. Ring-containing (meth)acrylates, dimethylaminoethyl (
meth)acrylate, aminoalkyl (meth)acrylates such as diethylaminoethyl (meth)acrylate, mono(meth)acrylates of alkylene oxide adducts of bisphenol A such as ethylene oxide and propylene oxide adducts of (I+) bisphenol A, ( 111) One in the molecule obtained by reacting a terminal incyanate group-containing compound obtained by reacting a diisocyanate compound and one or more alcoholic hydroxyl group-containing compounds in advance with an alcoholic hydroxyl group-containing (meth)acrylate. Urethane-modified mono(meth)acrylates having (meth)acryloyloxy groups, (1■
) Epoxy mono(meth)acrylates obtained by reacting a compound having one or more epoxy groups in the molecule with acrylic acid or methacrylic acid; Examples include oligoester mono(meth)acrylates obtained by reacting a polyvalent carboxylic acid with a polyhydric alcohol having a divalent or higher valence as an alcohol component.

Examples of photopolymerizable compounds having two photopolymerizable double bonds in the molecule include (1) ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol; Alkylene glycol di(meth)acrylates such as di(meth)acrylate, neobentyl glycol di(meth)acrylate, 1,6-hexanethiol di(meth)acrylate, diethylene glycol di(meth)acrylate,
Polyoxyalkylene glycol di(meth)acrylates such as triethylene glycol di(meth)acrylate, dibrobylene glycol di(meth)acrylate, polyprolene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, (11
) di(meth)acrylates of alkylene oxide adducts of bisphenol A, such as ethylene oxide and propylene oxide adducts of bisphenol A;
) An intramolecular compound obtained by reacting a terminal isocyanate group-containing compound obtained by reacting a diincyanate compound with two or more alcoholic hydroxyl group-containing compounds in advance with an alcoholic hydroxyl group-containing (meth)acrylate. Urethane-modified di(meth)acrylates having two (meth)acryloyloxy groups, (obtained by reacting a compound having two or more epoxy groups in one molecule with acrylic acid or/and methacrylic acid) Eboxy di(meth)acrylates, oligoester di(meth)acrylates obtained by reacting acrylic acid or methacrylic acid as a carboxylic acid component and a polyhydric carboxylic acid with a polyhydric alcohol of dihydric or higher valence as an alcohol component, etc. There is.

Examples of photopolymerizable compounds having three or more photopolymerizable double bonds in the molecule include (i)) trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaerythritol tetra Poly(meth)acrylates of trivalent or higher aliphatic polyhydric alcohols such as (meth)acrylate, (11
) A terminal inocyanate group-containing compound obtained by reacting a diisocyanate compound and a compound containing three or more alcoholic hydroxyl groups in advance, is further reacted with an alcoholic hydroxyl group-containing (meth)acrylate.
(jii) epoxy obtained by reacting acrylic acid or/and methacrylic acid with a compound having three or more epoxy groups in the molecule; Examples include poly(meth)acrylates.

The blending ratio of the epoxy compound (A) used in the present invention and the photopolymerizable compound (B) having a carboxyl group in the molecule, or a mixture of (B) and another photopolymerizable compound (C) is epoxy Compound (A): Photopolymerizable compound [(B)
or (B) + (C) ) -10: 90-90:
10 (it weight ratio range, preferably epoxy compound (A) Nikoto synthetic compound [(B) or (B) +
(C) ) -20:so to 80:20 (weight ratio). The blending amount of epoxy compound (A) is 10
If the amount is less than % by weight, the reaction between the photopolymerizable compound (B) having a carboxyl group in the molecule and the epoxy compound (A) is substantially too small, making it difficult to obtain a cured product with excellent adhesiveness, heat resistance, etc. . Furthermore, if the amount of the epoxy compound (A) exceeds 90% by weight, the curable resin composition will have a high viscosity and will be difficult to handle. I can't make use of it.

The photoinitiator (D) used in the present invention is a compound that promotes the photopolymerization reaction of a photopolymerizable compound, such as ketals such as benzyl dimethyl ketal, benzoin methyl ether, benzoin ethyl ether, pentuin-
Benzoins such as 1-propyl ether, benzoin and α-methylbenzoin, 9.10-anthraquinone,
Anthraquinones such as 1-chloroanthraquinone, 2-chloroanthraquinone, 2-ethylanthraquinone,
Benzophenones such as benzophenone, p-chlorobenzophenone, p-dimethylaminobenzophenone, 2
-Hydroxy-2-methylpropiophenone, 1-(4
-Inglobylphenyl) -Propiophenones such as 2-hydroxy-2-methylpropiophenone, suberones such as dibenzosperone, sulfur-containing compounds such as diphenyl disulfide, tetramethylthiuram disulfide, thioxanthone, methylene blue, eosin ,
Examples include pigments such as fluorescein, 3,3°, 4,4°-tetra-(t-7' tilperoxycarbonyl)benzophenone, and these may be used alone or in combination of two or more.

In the present invention, the blending amount of the photoinitiator (D) is 0.0000% relative to the total amount of the epoxy compound (A) and the photopolymerizable compound.
05-20% by weight, preferably 5-10% by weight
It is.

The curing accelerator (E) used in the present invention is a compound that promotes the reaction between an epoxy group and a carboxyl group, and examples thereof include 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 1 -Imidazoles such as benzyl-2-methylimidazole, benzyldimethylamine, triethanolamine, N, N-
These include tertiary amines such as dimethylamine ethanol, N,N-diethylaminoethanol, N,N-dipropylaminoethanol, and tertiary amine salts such as tridimethylaminomethylphenol triacetate and tribenzoate. Or two or more kinds are used in combination.

In the present invention, the addition of these reaction accelerators (E),
is 0.05 to 5% by weight, preferably 0.1 to 3% by weight, based on the total amount of the epoxy compound (A) and the photopolymerizable compound.
．． It is 5% by weight.

The curable resin composition used in the present invention is easily produced by stirring and mixing at room temperature or under heating if necessary. To prevent thermal polymerization during manufacturing and dark reactions during storage,
No-hydroquinone, no-hydroquinone monomethyl edel, 1-butyl-catechol, p-benzoquinone, 2.
It is desirable to add a known thermal polymerization inhibitor such as 5-t-butylrubidroquinone or phenothiazine. The amount added is 0.001 to 3.0% by weight, preferably 0.05% by weight, based on the photopolymerizable compound 41/J used in the present invention.
~1.0% by weight.

In addition to the above-mentioned additives, the curable resin composition used in the present invention may contain various additives such as known colorants, coupling agents, surface smoothing agents, antifoaming agents, fillers, glass beads, etc., as necessary. can be added.

In the method of curing the curable resin composition used in the present invention, the photopolymerizable compound (B) having a carboxyl group or (B) and another photopolymerizable compound (C
) is polymerized to form a carboxyl group-containing polymer, and then heated to cause the epoxy compound (A) to react with the carboxyl groups contained in the polymer to completely cure it.

Photopolymerization reaction conditions: light intensity 20 mW/ci ~ 20
At 0 m, W/cyh, a time of 0.1 seconds to 5 minutes is suitable. In addition, as for the thermosetting reaction conditions, the temperature is 40'C to 25°C.
Preferably, the time is 10 seconds to 120 minutes at 0°C.

The curable resin composition used in the present invention does not require active light such as ultraviolet rays or electron beams. Irradiate to induce a polymerization reaction. As a light source used for ultraviolet irradiation, sunlight θ, a chemical lamp, a low pressure mercury lamp, a high pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, etc. are used.

When irradiating with an electron beam, a photoinitiator (D>) is not necessarily required.

The heat source used for heating is VX, and known heating methods such as infrared heater, hot air heating, and high frequency heating are used.

The curable resin composition used in the present invention can be molded by any method, but casting molding, mold molding, etc. are common. Furthermore, there is a method in which the disk substrates are cut out from a molded plate and a method in which the disk substrates are molded one by one.

Both are molded by irradiating active light such as ultraviolet rays and then heating.

(Effect of the invention) The present invention brings about the following effects.

1) Since the resin composition is cured by actinic rays and heating, the resin composition does not become oriented during curing, and a disk with excellent optical isotropy can be obtained. 1. The cured product itself has excellent light transmittance.

2) The fluidity of the resin composition is lost in an extremely short time by irradiation with actinic rays, making it easy to handle, speeding up the production line and greatly improving product yield.

3) Since the optical information recording disk of the present invention is obtained from a curable resin composition, it has excellent dimensional stability under humidification.

4) It saves energy because so-called injection molding machines and molds are not used.

5) It is possible to cure thick parts, which is difficult to do with conventional ultraviolet curable resins, and it is possible to obtain a homogeneous substrate.

6) Various types constituting the aluminum reflective film and the disk substrate are listed, but the present invention is not limited to these examples in any way. In the examples, parts and parts indicate parts by weight, respectively. The resin properties of the curable resin composition and the performance of the cured product were measured by the following method.

■) Viscosity: Measured at 25°C using a Brookfield viscometer according to JIS K6901.

2) Light transmittance: Wavelength 400 nm to 8 for casting plate with thickness 2
The light transmittance in the 00 nm region was measured using a spectrophotometer (Model 320, manufactured by Hitachi Seisakusho), and the average value is shown.

3) Optical isotropy: A Selmon compensator equipped with a polarizing microscope was used, and a sodium lamp was used as the light source. Optical isotropy is expressed by an R value expressed by the following formula.

R=+dln, -n, 1 In the formula, d is the thickness of the casting plate (m), n, U are the refractive index in any direction, and n2 is the refractive index in the direction orthogonal to the n1 direction.

=22- 4) Dimensional stability: The rate of dimensional change was measured after a casting plate with a thickness of 2u was immersed in water at 25°C for 24 hours.

5) Surface hardness: The pencil hardness of the surface of a casting plate with a thickness of 2 mm was measured.

6) Adhesion A thin aluminum film was sputtered onto the two substrates, and the adhesion was evaluated by a Sellotape peel test method.

Example 1 Epicote 8, a bisphenol A type epoxy compound
28 (manufactured by Yuka Shell Epoxy) 38 parts, succinic acid mono-(2-methacryloyloxy-3-acryloyloxyisopropyl) ester 58 parts, tetraethylene glycol dimethacrylate 32 parts, 2-hydroxy-2-methyl A curable resin composition (a) of the present invention was obtained by stirring and mixing 5 parts of propiophenone and 0.5 part of N,N-diethylaminoethanol. The viscosity of the obtained curable resin composition (a) was 12 voids. Next, the obtained curable resin composition (a) was injected between two glass plates sandwiching a 2n-thick spacer, and then
Irradiated with mW/cm ultraviolet light for 10 seconds, then 120°
A casting plate having a thickness of 2MII+ was prepared by heating at C for 30 minutes. Table 1 shows the performance of the obtained casting plate. Furthermore, as a reference, the performance of commercially available polycarbonate base materials and polymethyl methacrylate base materials was also measured and is also listed in Table 1. In addition, when the pot life of the resin composition (a) was measured, no deterioration was observed even after one month at 25°C.

Table 1 Example 2 Epicote 1, a bisphenol A type epoxy compound
001 (manufactured by "R Oil Shell Epoxy"), 48 parts of succinic acid monoacryloyloxyethyl ester, and 70 parts of tetrahydrofurfuryl acrylate were placed in a stirring container, and mixed and stirred at 80 ° C. to obtain a transparent resin composition. is. 0.5 parts of 2-hydroxy-2-methylpropiophenone as a photoinitiator per 100 parts of this resin composition.
1 part and 0.5 part of N,N-diethylaminoethanol as a curing accelerator to obtain a curable resin composition (b) of the present invention. Then, in exactly the same manner as in Example 1, a thickness of 2
A casting plate of H was created. The performance of the obtained casting plate was as follows. In addition, when the pot life of the resin composition (b) was measured, no deterioration was observed even after one month at 25°C.

Table 2 Comparative Example 1 Epicote 8, a bisphenol A type epoxy compound
28 (manufactured by "R Oil Shell Epoxy") 100 parts, hexahydrophthalic anhydride 80 parts, benzyldimethylamine 1
．． 8 parts and 0.2 parts of triphenyl phosphite as a coloring inhibitor were placed in a stirring vessel, and mixed and stirred at 50°C to obtain a transparent thermosetting resin composition (C). The obtained thermosetting resin composition (C) had a viscosity of 178 poise. This thermosetting resin composition (C) was injected between two glass plates sandwiching a spacer with a thickness of 2 wings in the same manner as in Example 1, and then heated at 120°C for 2 hours to obtain a thickness of 22 cm.
A casting plate of 61n was prepared. The performance of the obtained casting plate was as follows, but this thermosetting resin composition (C) had a significantly short pot life and gelled on the second day at 25°C.

Table 3 Comparative Example 2 40 parts of diacrylate of 4 moles of ethylene oxide adduct of bisphenol A, 15 parts of tetrahydrofurfuryl acrylate, and 15 parts of trimethylolpropane triacrylate were placed in a stirring container, mixed and stirred at room temperature, and a transparent resin composition was obtained. I got it. 3 parts of benzoin ethyl ether was added to 100 parts of the obtained resin composition to obtain an ultraviolet curable resin composition (d). The obtained ultraviolet curable resin composition (d) had a viscosity of 5 voices. Next, in the same manner as in Example 1, the ultraviolet curable resin composition (d) was injected between two glass plates sandwiching a 2ff-thick spacer, and 200 mW/- ultraviolet rays were irradiated for 60 seconds, but the surface only hardens, the inside remains liquid, and the thickness is 2
I was unable to create a pouring board for drunkenness.

Claims (1)

[Scope of Claims] An optical information recording disc characterized by having a recording layer formed on one side of a flat plate formed by molding the following composition. Compound (A) having two or more epoxy groups in the molecule,
A photopolymerizable compound (B) having one or more carboxyl groups in the molecule, or a mixture of the compound (B) and another photopolymerizable compound (C), a photoinitiator (D) and a curing accelerator ( A curable resin composition consisting of E).