JPS60209938A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a substrate which has excellent heat resistance, thermal shape retentivity, moisture resistance and water resistance and is further adjusted as desired in refractive index by using a soln. contg. vinyl silane in treating an epoxy resin substrate. CONSTITUTION:A substrate for an optical disk consists preferably of an arom. resin and alicyclic resin in a 9:1-1:9 ratio range. The refractive index is too large if the ratio of the arom. resin is more than said range and conversely the refractive index is too small if the rate of the alicyclic resin is more than said range. A bromoepoxy resin is usable suitably usable as well. A combination of an arom. hardener and alicyclic hardener is preferable as a hardener. The hardened material having the higher refractive index is obtd. with the higher concn. of the arom. ring. The vinyl silane is ethylenic unsatd. silane, e.g. methacryloxy alkyl silane such as gamma-methcryloxy propyl trimethoxysilane and the ratio of the vinyl silane and lower alcohol is preferably 1:8-1:10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an epoxy resin cast cured cut-up substrate on an optical recording medium, and transferring a predetermined irregularity of the entire original plate with an ultraviolet curable resin and a stamper force of ≧ to δ. It is.

These predetermined irregularities are signal bits in video discs and digital audio discs, and guide grooves in discs used for image files and computer files.

Conventionally, the substrates used in so-called optical recording media are either glass or transparent synthetic resin substrates, and in order to avoid birefringence, optically isotropic materials are used. Jaku9, polymethyl methacrylate, polysulfone,
Polycarbonate, polyvinyl chloride, copolymers of vinyl chloride and tovinyl acetate, and the like have been proposed. 1, Takura r-rL, I-, in the house I7 wa 4
Polymethyl methacrylate (PMMA) is used in most cases. Polymethyl methacrylate (PMMA) substrates are generally obtained by injection molding. However, polymethyl methacrylate)
In the case of (PMMA) substrates, the following drawbacks become major problems as the reliability of the medium begins to be required as the recording density increases.

■Due to poor heat resistance, when various functional films are vaporized, the temperature of different surfaces of the substrate increases, causing deformation.

@Since it is a thermoplastic resin, creep may occur due to centrifugal force during high-speed rotation during access.

Furthermore, if exposed to high temperatures during storage, deformation occurs, which increases surface play due to so-called rotation.

Since θ hygroscopicity is dog, if hygroscopic deformation occurs, 71\,
If the oxidation of the cage film is promoted, the following problems will occur.

Since it is manufactured by O injection molding, molding distortion remains and birefringence occurs.

■Adjusting the refractive index is difficult and is limited to one refractive index.

etc.

In order to overcome such drawbacks, the inventors of the present invention first investigated substrates using various resins, and developed an epoxy resin composition*' consisting of an epoxy resin, an organic polybasic acid anhydride, a curing accelerator, and a discoloration inhibitor. It has been found that a substrate obtained by thermoforming can be used as an optical recording medium and eliminates the above-mentioned drawbacks.

In addition, in order to form all the signal pits and guide grooves on the substrate, after applying ultraviolet curable resin and pressing the master standber, the substrate surface force and
All conventional methods were used, including irradiating the resin layer with ultraviolet light to cure the resin layer, removing the mold, and transferring the unevenness. However, by changing the substrate to a cured epoxy resin, the following problems arose.

In other words, since the resin constituting the substrate is an anhydride-cured epoxy resin, the hydroxyl groups in the resin skeleton make the interface significantly more hydrophilic than that of acrylic resins, unlike in ordinary UV-curable resin systems. The adhesion was poor. As a way to overcome this drawback, we used an acrylic monomer having a hydrophilic group such as 10H group or -COOH group as a crosslinking agent in the resin system, which resulted in good adhesion to the metal master having a hydrophilic interface. It became impossible to remove the mold.

In order to solve this problem, the inventors of the present application have earnestly investigated a method of treating the epoxy resin base metal using a hot vinyl silane liquid. Heading ratio. That is, at the epoxy resin interface, the silane of the vinyl silane compound and the 10H group remaining in the epoxy resin skeleton? React and then 7
11] Is it compatible with UV-curable resins that are hydrophobic and polymerized with vinyl foundations through heat treatment? The inventors of the present invention have found a method for increasing the mold releasability between the resin and the master disk.

The epoxy resin used in the present invention is liquid at room temperature and can be applied to all types of liquid bisphenol A.
Resins such as resins, alicyclic epoxy resins, and aliphatic epoxy resins are used. In addition, using a complete mixture of these epoxy resins means that this boxy resin and liquid bisphenol A
Is the refractive index of the cured product obtained depending on the mixing ratio of M type fats? This is important in that it can be adjusted as appropriate.

Also, the mixing ratio is important, and is the relationship between the mixing ratio and the refractive index a linear relationship? Through detailed research, we have discovered the interesting fact that For optical disk substrates, the ratio of aromatic resin to alicyclic resin is preferably in the range of 9 = 1 to 1;9, and if the amount of aromatic resin exceeds this range, the refractive index becomes sharp. On the other hand, if there is a large amount of alicyclic resin, the refractive index will become small. Furthermore, brominated epoxy resins can also be used as appropriate.

Any acid anhydride used as a curing agent in the present invention can be used as long as it has excellent compatibility with the liquid epoxy resin, but in particular, hexahydro-7-talic anhydride, tetrahydrophthalic anhydride, methyltetrahydro- Phthalic anhydride, endomethylenetetrahydrophthalic anhydride,
Aliphatic or alicyclic hardeners such as polyacelaic anhydride, unsaturated aliphatic or aromatic hardeners such as acid, pyromellitic anhydride, etc. are also included in the above resins. Mixed use is also effective for the same reasons as in case
In particular, a combination of an aromatic curing agent and a cyclic curing agent is desirable. As for the curing agent, the higher the aromatic ring concentration, the higher the refractive index of the cured product.

The curing accelerator used in the present invention is 2-ethyl-4
-Methylimidazole, 2-methylimidazole, l-
There are imidazoles such as benzyl-2-methylimidazole, 8th class amines, etc., but imidazoles are preferable.

The anti-discoloration agent is also important in the present invention and contributes to light transmission stability.

As these discoloration inhibitors, hindered phenols such as 2-6-ditertiary-butylphenol, organic sulfides, organic heptatoosphites, higher fatty acid salts, etc. are used alone or in combination.

Particularly in order to ensure complete discoloration stability under high temperatures, the effect of these combinations may be remarkable.

Furthermore, the vinyl silane referred to herein is an ethenically unsaturated silane, particularly a methacryloxyalkylsilane such as γ-methacryloxypropyltrimethoxysilane. Examples of lower alcohols include methanol, ethanol, provia alcohol, isopropyl alcohol, and the like. Also, the ratio of vinyl silane and lower alcohol is 1:8.
~1:10 is preferred. Also, the heating temperature is 50°0~120
It is preferably carried out at a temperature of 80°C x 100°C, and the treatment time varies depending on the temperature, but is usually 10 to 6°C.
This is done within a range of 0 minutes.

Is the UV curing resin a monomer or oligomer of acrylic acid or methacrylic acid monoester, diester, triester, or tetraester? It is the main ingredient.

For example, ethyl acrylate, n-butyl acrylate,
Alkyl acrylates, alkoxyalkyl acrylates, phenoxyalkyl acrylates 2 and phenyl acrylates and diacrylates, such as hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, octadecyl acrylate, ethoxyethyl acrylate 2 and phenoxyethyl acrylate, such as 1.8- Alkanediol diacrylates 3 such as propane diol diacrylate, diethylene glycol diacrylate 2 and tetraethylene glycol diacrylate 3 and alkene glycol diacrylates and triacrylates such as trimethylolpropane triacrylate and pentaerythritol triacrylate and tetraacrylates such as penta Oligomeric acrylic esters of erythritol tetraacrylate, such as polyethylene glycol acrylate, urethane acrylate, polyester acrylate, and epoxy arylate.

Regarding the photoinitiator, the light transmission characteristics of the transparent resin substrate should be taken into consideration, and since the epoxy resin substrate hardly transmits light with a wavelength of 290 nm or less,
Suitable photoinitiators with good sensitivity in a relatively long wavelength range, such as 2,2-dimethoxy-2-phenylacetophenone, benzoin isobutyl ether, or combinations thereof, are preferred. Further, for the purpose of imparting toughness, a polythiol compound t2 to 10, preferably about 5 weight S, can be added to 100 parts by weight of the main component. If more than 10 parts by weight is added, favorable results cannot be obtained in terms of heat resistance, hardness, glass transition point, etc. Furthermore, if necessary, stabilizers, discoloration inhibitors, anti-fouling agents, etc. may be added to the ultraviolet curable resin system.

The substrate obtained by the present invention has excellent heat resistance, thermal shape retention, moisture resistance, and water resistance compared to conventional substrates, and also has a refractive index arbitrarily adjusted.

Examples are listed below.

Example 1 iFC set consisting of epoxy resin and curing agent with the following formulation
Adjusted wlJ.

Blended composition A Liquid bisphenol A type epoxy resin 100 parts by weight Methylhexahydrophthalic anhydride 88 1 Benzene hydroxytoluene 1.0 #2-Ethyl-4-methylimidazole o5 l Blended composition B Alicyclic epoxy resin 100 Heavy it part Methyl hexahydrophthalic anhydride 122 l Benzene hydroxytoluene 1.0 #2-ethyl-4-
Methylimidazole 2.0# Next, the above formulations were mixed in a ratio of 1:1 to obtain a resin composition for casting.

The mixed resin composition was injected into a 1.5 mm thick cavity formed from two glass plates, defoamed, and cured by heating at 120° C. for 2 hours. Furthermore, the glass plate was released from the mold to obtain an epoxy resin substrate.

Then the substrate was placed in a lO-thiethanol bath of dipropyltrimethoxysilane in γ-methacrylic acid. After soaking, 8
It was heat-treated in a hot air dryer at 0° C. for 80 minutes, and washed with n2 acetone. Next, it is coated with ultraviolet curable resin, pressed against a master disc with predetermined irregularities, irradiated with ultraviolet rays from the back side, and after the resin R is cured, it is peeled off from the master disc, and the ultraviolet curable resin with predetermined irregularities becomes strong. The densely layered rear body was removed.

Moreover, it was easy to peel off from the master disc. Further, the formulation of the ultraviolet curing resin used at this time was as follows.

Liquid bisphenol A-based epoxy arylate 60 parts by weight Pentaerythritol triatarate 40
I2 + 2-:) Methoxy-2-phanylacetophenone 81 Example 2 After obtaining a substrate in the same manner as in Example 1, a resin layer was entirely formed on the substrate using the following ultraviolet curable resin composition, and this resin layer A master disc with guide grooves was pressed against the base plate through the base plate, and ultraviolet rays were irradiated from the base surface to harden the resin.

Pentaerythritol tetrathioprobionate 60
Part by weight Triaryl isocyanate 40 N benzoin isobutyl ether 8I When the substrate gold was peeled off from the master, it was easily peeled off, and the guide grooves were faithfully transferred to the ultraviolet curing resin layer. Obtained.

Comparative Example 1 The same experiment as in Example 1 was conducted without hair-treating the surface of an epoxy resin substrate. The cured 1f11 oil layer did not adhere to the substrate surface at all, and a film with unevenness was peeled off from the substrate surface.

Comparative Example 2 A method similar to Example 1 was attempted using the following formulation using hydrophilic 7-mer as an ultraviolet curable resin, but without treating the substrate surface.

Liquid bisphenol A-based epoxy acrylate 60-ms2-hydroxy-ethyl, methacrylate 4
0 N benzoin isobutyl ether 8I In this case, the ultraviolet-cured #1 resin layer adhered to the substrate surface and the master surface, making it impossible to remove the mold at all.

Claims (1)

[Scope of Claims] (1) After obtaining a cast transparent cured epoxy resin consisting of an epoxy resin, an organic polybasic acid anhydride, a curing accelerator, and a discoloration inhibitor, the transparent substrate? A step of immersing the surface in a lower alcohol solution containing vinyl silane and subjecting it to heat treatment at a temperature of 50'C or higher, and applying ultraviolet curing to the treated surface.
Optical recording is characterized in that it consists of a step of applying pressure to a master or stamper having a predetermined unevenness after coating, hardening it with ultraviolet rays, and then removing the mold and transferring all of the predetermined unevenness to the substrate. Method of manufacturing media. (2) The epoxy resin is a mixture of aromatic epoxy resin and alicyclic epoxy, and the blending ratio is 9:1 to 1:9.
A method for manufacturing an optical recording medium according to claim (1). (8) The epoxy resin is an aromatic epoxy resin and an alicyclic di,
Claim (1) or i12) in which the refractive index of the cured product is adjusted to a constant value in the range of 1.50 to 1.60.
A method for producing an optical recording medium as described in Section 3.