JPS6251054A - Production of optical disk - Google Patents

Abstract

PURPOSE:To improve productivity by disposing a base laminated with a thin film in information tracks having fine structure into a casting mold, pouring a prepolymer soln. which can be thermoset into the cavity in the casting mold and rotating a rotating body connected to the casting mold. CONSTITUTION:The casting mold to be used is constituted of an upper part 8 of the casting mold and a lower part 9 of the casting mold and is connected to a revolving shaft 10. The base 6 laminated with the thin metallic film in the information tracks 7 having the fine structure is disposed in the casting mold. After the base 6 is disposed in the casting molds 8, 9, the prepolymer soln. is poured through a pouring port 12 into the cavity 11 in the casting mold. The prepolymer soln. is fluidized to the peripheral side by centrifugal force and the foam, etc. intruded therein are released from the concentrical side when the shaft 10 connected to the casting mold is rotated. The curing of the prepolymer soln. progresses when the rotation is further continued and the casting mold is heated.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for manufacturing an optical disc suitable for digital audio discs, optical discs, magneto-optical discs, and the like.

``The problem with the prior art is that optical disks with a phantom metal thin film are used in recording and reproducing devices that focus laser light onto a rotating disk and detect the strength and weakness of the reflected light from the disk. It is a composite molded body consisting of a thin metal film layer and a protective layer for protecting the metal thin film as necessary.

Glass, thermoplastic acrylic resin, and polycarbonate resin are used for the transparent substrate layer, but the water absorption resistance, disk strength, low birefringence, and heat resistance required for optical disk substrates are insufficient. Thermosetting epoxy resins, thermosetting unsaturated epoxy ester resins, etc. are recognized as having fewer of the above-mentioned drawbacks.

However, thermosetting resins have extremely poor precision moldability due to their high heat shrinkage, poor mold release properties, and complicated work processes because they are made from two-component compounds. When making an optical desk board, for example, a flat plate is made by casting a thermosetting resin, an ultraviolet curing paint is applied onto the mold with the inverted fine information tracks, and after the flat plate is pressed, it is exposed to ultraviolet rays. After curing by irradiation, the mold is released. Conventionally, optical discs having a transparent thermosetting resin substrate layer and a metal thin film layer are manufactured by cleaning the precision thermosetting resin substrate obtained in this way, and depositing metal on the fine information track side to form a recording layer. Furthermore, it is obtained by forming a protective layer by painting or the like. If an optical disc that can be attached and recordable on both sides is required, a method has been proposed in which adhesive is applied to both sides of the spacer and the protective layer sides of the two optical discs are brought into contact and bonded. A sectional view of the original desk with such a structure is shown in FIG.

``Problems to be solved by the invention'' Optical disks with excellent water absorption resistance, disk strength, low birefringence, and heat resistance undergo complicated processes as described above.
It has serious drawbacks, such as extremely low productivity and the need for a large amount of manufacturing equipment.As a result of intensive consideration of countermeasures, we found that
It has been found that this problem can be solved by the present invention.

[Structure of the invention]

``Means for Solving the Problems'' That is, the present invention places a support in which a metal thin film is laminated on microstructured information tracks in a casting mold, and pours a thermosetting prepolymer solution into the casting mold. A support body and a thermosetting resin transparent substrate characterized in that the solution is injected into a cavity in a mold, and a rotating body connected to a casting mold is rotated, and the solution is heated and hardened while being pressed against the mold by centrifugal force. This is a method for manufacturing an integrally molded optical disc.

The support used in the present invention, in which a metal thin film is laminated on a microstructured information track, is generally a disc-shaped support, and the information track is grooved in a circular or spiral shape. has been done. The support may be made of any material that does not undergo thermal deformation during molding, such as a steel plate, aluminum plate, or glass plate, but thermoplastic resin plates that are light, strong, and have good injection moldability are particularly suitable. Preferably, a methyl methacrylate plate, a polycarbonate plate, or a hard polyvinyl chloride resin having a high heat distortion temperature is used. In thermoplastic resins, supports with microstructured information tracks can be obtained by injection molding. In addition, in the case of aluminum plates, glass plates, etc., for example, an ultraviolet curable paint is applied on a mold with an inverted fine information track, and after this and the plate are bonded, UV rays are irradiated to release the mold and the fine structure is created. Get support with information tracks.

A metal or metal oxide layer is formed on the surface of the support having the microstructured information tracks thus obtained using a sputtering device or a vapor deposition device. As metals or metal oxides, AI%Dys Sn%To, Tb, Gd
It is an elemental metal, an alloy, or a compound thereof, which is mainly composed of A! ,Te C1T@To
o, ,To-8s%5b-8s/B1-Tl,Tb-
Fe-Co, To-TiAgSe, Tb-Dy-F
eCd Tb Fes Gd Fs, Tb-Fe
, can be listed.

Metal ¥J on the microstructure information track obtained in this way!
The support with the laminated base is placed in a casting mold, a thermosetting prepolymer solution is injected into the space inside the casting mold, and a rotating body connected to the casting mold is rotated to remove the bath by centrifugal force. The liquid is heated and cured while being pressed against the mold to produce an optical disk in which the support and the thermosetting resin transparent substrate are integrally molded.

A thermosetting prepolymer solution is a mixed solution of two or more components, such as a base resin and a curing agent, a base resin and a catalyst, and a prepolymer having a molecular weight of at least 300 and having at least two functional groups. It contains 30% or more in the resin, and forms a thermosetting resin transparent substrate after thermosetting. Examples of the prepolymer solution include liquid epoxy resin.
hardening agent, polyisocyanate-polyol, unsaturated epoxy ester-polymerizable monomer, unsaturated urethane oligomer-polymerizable monomer, liquid epoxy resin-amine curing agent, polyisocyanate-polyamine, unsaturated polyester-polymerizable It is a monomer.

In a liquid epoxy resin-acid curing agent system, the liquid epoxy resin corresponds to the prepolymer component, and diglycidyl ether of bisphenol A is a typical example thereof.

Examples of acid curing agents include polycarboxylic acid anhydrides such as hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, Nadic methyl anhydride ring, etc., glycol or polyol, and #anhydride. Examples include polycarboxylic acid compounds typified by carboxyl group-terminated adducts obtained by reacting substances.

In the curing agent system of the liquid epoxy resin, tertiary amines, imidazoles, metal salts of carboxylic acids, etc. can be used as curing accelerators in order to improve molding productivity.

In a polyinocyanate-polyol compound solution made from diisocyanate, either or both of the polyisocyanate component and the polyol compound correspond to the prepolymer component. Typical examples of diisocyanates include hexamethylene diisocyanate, xylylene diisocyanate, inphorone diisocyanate, lysine diisocyanate, etc. These can be used alone or modified with fine compounds to form isocyanurate-based polyisocyanates and picolet-based polyisocyanates. , used in the form of polyurethane polyisocyanates.

As polyol compounds, in addition to alkylene glycols represented by ethylene glycol and alkylene polyols represented by trimethylolpropane, polyether polyols and polyester polyols are used. In the polyisocyanate-polyol system, in order to improve molding productivity, a urethanization accelerator typified by dibutyltin dilaurate can be used.

In the unsaturated epoxy ester-polymerizable monomer system,
A solution of an unsaturated epoxy prepolymer obtained by reacting a polyepoxy compound with an unsaturated carboxylic acid and a polymerizable monomer is used. Representative examples of polyepoxy compounds include diglycidyl ether of bisphenol A, polyglycidyl ether of novolak phenol resin, and diglycidyl ether of glycol. Examples include unsaturated dicarboxylic acids such as saturated monocarboxylic acids, maleic acid, and fumaric acid. Typical examples of polymerizable monomers include methyl (meth)acrylate, hydroxyethyl (meth)acrylate, styrene, ethylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. A radical initiator represented by benzoyl peroxide and an accelerator represented by cobalt naphthenate can be added to the unsaturated epoxy ester prebolimer haK.

For the unsaturated urethane prepolymer-polymerizable monomer system, a solution of an unsaturated urethane prepolymer and a polymerizable monomer obtained by reacting an unsaturated hydroxy compound, a polyisocyanate, and if necessary a polyol is used. Sanru.

Examples of unsaturated hydroxy compounds include β-hydroxyethyl (meth)acrylate and pentaerythritol tri(
Typical examples include meth)acrylate, di- or mono(meth)acrylate of trimethylolpropane, and the like. As the polyisocyanate, non-yellowing polyisocyanates are suitable, and the aforementioned diisocyanates, incyanurate polyisocyanates, billet polyisocyanates, and polyurethane polyisocyanates are used. Typical examples of the polymerizable monomer include the aforementioned polymerizable monomers used in unsaturated epoxy prepolymer solutions.

The unsaturated polyester-polymerizable monomer system is a known unsaturated polyester resin consisting of a nine-unsaturated polyester obtained by condensing an unsaturated mono- or dicarboxylic acid with a glycol, and a polymerizable monomer.

As shown in FIG. 2, the casting mold used in the present invention is composed of an upper casting mold (8) and a lower casting mold (9), which are connected to a rotating shaft (10).

FIG. 3 shows an example of a partial cross-sectional view in which a supporting body (6) in which a thin metal film is laminated on a microstructured information track (C) is placed in a casting mold.

After placing the support (6) in the casting mold (81 (91), the prepolymer solution is injected into the cavity (11) in the casting mold from the injection port (12), and the rotating Axis (1
0), the prepolymer solution flows toward the circumference due to centrifugal force, and any air bubbles etc. mixed in are released from the center side. Furthermore, the two rotations heat the casting mold, and the prepolymer solution hardens. Note that it is optional to provide a known protective film layer, preferably on both sides of the metal thin film layer, to protect the metal thin film layer.

〔Example〕

"Prepolymer solution preparation example 1" Epiclon ■850 (diglycidyl ether of bisphenol A manufactured by Dainippon Ink Chemical Industry ■) 100 parts by weight C
A thermosetting prepolymer solution (8) was prepared by blending 35 parts of Laccamite ■WH-042 (amine adduct of epoxy resin manufactured by Dainippon Ink & Chemicals ■, amine value 380).

"Prepolymer solution preparation example 2" Polylite ■8010 (manufactured by Dainippon Ink & Chemicals ■, unsaturated polyester resin, styrene content 33%) 100
part, cobal naphthenate (C) content 6%) 0.2 part,
Mix 2.0 parts of P-MEC N and prepolymer solution (
Bit-Created.

"Prepolymer solution preparation example 3" 22bis[35dibromo4(2glycidyl)phenyl1
70 parts of 22bis[35dibromo4(2methacryloyloxy, hydroxyisopropoxy)7dyl]propane, 30 parts of styrene, 3 parts of lauroyl peroxycarbonate, obtained by reacting 2 moles of methacrylic #7t with 10721 moles. and 0.2 parts of 2(2'hydroxy5'methylphemyl)benzotriazole were mixed to prepare a prepolymer solution.

A transparent substrate was molded by casting using the above prepolymer and its performance was evaluated.

For molding, resin was injected into a glass mold coated with a molding agent. Prepolymer A was heated at 60°C for 20 minutes, and prepolymer B was heated at 60°C for 5 minutes.
Prepolymer C was cured at 0°C for 8 hours, and Prepolymer C was cured at 40°C for 3 hours.

Each characteristic was under-represented.

Prepolymer A Prepolymer B Prepolymer C Light transmittance% 90 88 90 (wavelength 60
0 nm) Water absorption % 0.3L150.6 Bending strength (kg/1sc) IAo 1Q, 0
110 Birefringence (nw) 7 20 10 (
Double pass) Heat resistance ("C) 130 85 100 Example 1 A support with a diameter of 300% and a thickness of 12 mm made of polymethyl methacrylate and having the structure shown in FIG. 2 6,
A To-based low oxide recording material was deposited on both sides with concentric grooves with a track pitch of 15 μm by vapor deposition at approximately 100 Ω.
The support (schematic plan view, Fig. 4) attached to the thickness of A,
Placed in the casting mold shown in Figure 2, a thermosetting prepolymer solution was injected into the cavity in the casting mold (cavity thickness: 12 m), and the nine-rotating body was connected to the casting mold at a rotation angle of 30 Or
Rotate at 60°C for 20 minutes to heat cure the optical disc (optical disc in which the support and thermosetting resin transparent substrate are integrally molded).
I) tl-obtained. A schematic cross-sectional view of the recorded portion of the optical fiber is shown in FIG.

Example 2 The same support as used in Example 1 was placed in the casting mold shown in FIG. The rotating body connected to the was rotated at 1,100 Orp and heat-cured for 5,008 hours to obtain an optical disc in which the support and thermoset transparent substrate were integrally molded.This was taken out of the casting mold and post-cured at 60°C for 24 hours.Optical disc (6) I got it.

Example 3 The same support as in Example 1 except that polycarbonate was used as the raw material was placed in the casting mold shown in FIG. 2, and a thermosetting prepolymer solution Ω was injected into the cavity in the casting mold. Rotate the rotating body connected to the casting mold at 30 rpm.40
The temperature was linearly raised from 40°C to 90°C for 3 hours and heat-cured for 15 hours, and the support and thermosetting resin transparent substrate were integrally molded to obtain a multiplication table disk. Frequency 5MH while rotating at 1800 rpm! , pulse width, 110
The recorded signal was written using a semiconductor laser with an output of 10 nW, and the recorded signal was reproduced using a semiconductor laser similar to the one in No. 9 with a laser light intensity of 1 nW.
C using a spectrum analyzer (Takeda, RIKEN TR-4171) under the conditions of a reference signal of 5 MHz and a band width of 3 QKHz.
The N ratio was measured.

In addition, each optical disc created was tested for humidity resistance (temperature: 60°C).
, 90% humidity, 100 hours), and changes in the light reflectance of the recording film before and after the humidity test were measured, and the humidity resistance of each disc was evaluated.

These results are shown in Table 1.

Table 1 CN ratio (dB) Decrease rate of reflectance % optical disc α)
53 30 light disk @
52 57 optical disk (2)
53 32 As explained above, by the method of the present invention, optical discs having excellent water absorption resistance, disk strength, low birefringence, and heat resistance can be produced extremely easily.

Note that the CN ratio correlates with the low birefringence of the thermosetting resin transparent substrate, and the decrease in the reflectance of the recording layer in the moisture resistance test depends on the water absorption resistance and heat resistance of the thermosetting resin transparent substrate.

〔Effect of the invention〕

According to the method for manufacturing an optical disk according to the present invention, (11) the unpolymerized solution is press-fitted into the mold part caused by polymerization shrinkage; (2) the heat of polymerization is easily dissipated by rotational movement; and (3) the foamed component is Because it is easy to pull out the parts, it is possible to use higher temperatures and a larger amount of catalyst than other casting methods, making it possible to manufacture optical disks with high productivity and good dimensional accuracy.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a conventional optical disk, FIG. 2 is a cross-sectional view of a casting mold used to carry out the method of the present invention, and FIG. 3 is a cross-sectional view of an example of a conventional optical disc. Truck (71
shows a partial cross-sectional view of a support (6) on which a metal thin film is laminated; in the figure, (1) is a substrate layer, (2) is an ultraviolet curing paint layer, (3) is a metal thin film layer, and (4) is a substrate layer. Haho #, (5)
is a spacer, (6) is a support, (force is an information track,
However, ) indicates the upper casting mold, (9) the lower casting mold, (10) the rotating shaft, and (11) the cavity. Agent: Patent Attorney Masaru Takahashi

Claims (1)

[Claims] A support with a metal thin film laminated on a microstructure information track is placed in a casting mold, a thermosetting prepolymer solution is injected into the cavity in the casting mold, and a rotating body connected to the casting mold is A method for manufacturing an optical disk in which a support and a thermosetting resin transparent substrate are integrally molded, the method comprising heating and curing the solution while rotating and pressing the solution against the mold by centrifugal force.