JPS62162509A - Manufacture of substrate for optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain a substrate of small optical distortion excellent, in moisture absorption, heat resistance, and solvent resistance, by a method wherein unsaturated polyester resin or vinyl ester resin composite which contains an organic peroxide and curing auxiliary agent and is in a liquid state at the normal temperature is cured by casting the same into a stamper having a matrix of a guide groove or an information pit pattern. CONSTITUTION:A liquid resin composite 1 obtained by compounding a curing agent an organic peroxide and curing auxiliary agent with unsaturated polyester resin or vinyl ester resin is cast into a stamper 2 having volds about 1mm in thickness, and cured at the normal temperature by putting a flat plate 3 over the same. A transparent substrate 4 to the upper part of the surface of which a pattern has been transferred is obtained as a monolithic molded product by using the stamper 2 having a guide groove or an information pit pattern on one side as a mold. As the liquid resin composite is cured by casting the same within the mold, a substrate f much smaller molding distortion and small optical distortion, is obtained and that the same is superior in transfer properties of the pattern of the same.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a substrate used for an optical information recording medium that records and reproduces information using a laser beam. The present invention relates to a method for manufacturing a substrate for an optical information recording medium, which is characterized by integrally curing a resin composition.

[Conventional technology and its problems]

Conventionally, glass or polymethyl methacrylate (hereinafter abbreviated as PMMA) has been used as a substrate material for optical information recording media that records and reproduces information using laser beams in order to meet the required characteristics of being transparent and having no birefringence. , thermoplastic resins such as polycarbonate, polyvinyl chloride, and polymethylpentene, and thermosetting resins such as epoxy resins and solid unsaturated polyester resins have been proposed (Japanese Patent Application Laid-Open No. 56-27323, 58-
108042, JP-A-58-166545). Among these, PMMA, polycarbonate, polyvinyl chloride, and the like have been put into practical use as substrates for optical discs for video and music.

The above-mentioned substrate made of thermoplastic resin is generally obtained by injection molding, but it has the disadvantage that it is difficult to remove minute molding distortions and birefringence occurs. In addition, in the case of PMMA, it has high hygroscopicity and causes warping, so it is necessary to rely on a method of bonding two substrates together on the back side.

Furthermore, for writeable and rewritable optical recording media, which have recently been developed, vapor deposition and solution coating methods are being considered as methods for forming a thin film recording layer on a transparent substrate. Heat resistance of the material is required, and in the latter case, solvent resistance of the substrate material, but the thermoplastic resins described above are insufficient in either performance.

On the other hand, thermosetting resins such as epoxy resins or solid unsaturated polyester resins can overcome many of the drawbacks of thermoplastic resins, but they require high temperatures and long periods of time to cure, resulting in poor moldability and poor moldability. There are problems in terms of productivity and energy costs.

Furthermore, a method has also been proposed in which a substrate is obtained by laminating a transparent support plate made of the above-mentioned resin material or glass and a photocurable resin. This involves disposing a liquid photocurable resin in the gap between the transparent support plate and a stamper having a guide groove or information pit pattern, and curing the photocurable resin by irradiating light from the side of the transparent support plate. Then, the transparent support plate and the photocurable resin layer are taken out as a laminate.

This method has excellent transferability of guide grooves or information pit patterns, but since it is a laminate, deformation due to warping and
It has problems such as peeling due to insufficient adhesion between the eyebrows and high cost due to the large number of steps.

[Purpose of the invention]

An object of the present invention is to solve the problems of the prior art described above and to provide a substrate for an optical information recording medium that has low optical distortion and excellent moisture absorption, heat resistance, and solvent resistance.

[Means for solving problems]

As a result of intensive studies to solve the above-mentioned problems, the present inventors discovered that the above-mentioned problems could be solved by integrally curing a specific resin composition that is liquid at room temperature. completed.

That is, in the present invention, an unsaturated polyester resin or vinyl ester resin composition which is liquid at room temperature and contains an organic peroxide and a curing agent is poured into a stamper having a matrix having a guide groove or an information pit pattern, and then cured. The present invention provides a method of manufacturing a substrate for an optical information recording medium, which is characterized in that:

In the present invention, the unsaturated polyester resin that is liquid at room temperature refers to ethylenically unsaturated polybasic acids such as fumaric acid and maleic anhydride (if necessary, saturated polybasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, and adipic acid). Basic acids can be added.

) and glycols such as ethylene glycol, propylene glycol, neopentyl glycol, ethylene oxide adducts of bisphenonyl A, and propylene oxide adducts of bisphenol A. It is a liquid resin dissolved in a polymerizable monomer such as diallyl phthalate.

Furthermore, the vinyl ester resin that is liquid at room temperature in the present invention is also called an epoxy acrylate resin or an unsaturated epoxy ester resin, and several manufacturing methods are known.

That is, (1) an epoxy resin having at least one epoxy group in its molecule and an unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid (or if necessary, a part or most of the unsaturated monocarboxylic acid is replaced with a saturated monocarboxylic acid); (substituted with one or more selected from carboxylic acids, saturated or unsaturated polycarboxylic anhydrides, and saturated or unsaturated alkyds having terminal carboxyl groups) in the presence of a catalyst. A method of dissolving the unsaturated ester resin obtained by the reaction in a polymerizable monomer such as styrene, methyl methacrylate, diallyl phthalate, etc.; With Esther,
This method involves dissolving an unsaturated ester resin obtained by heating and reacting in the presence of a catalyst in the same polymerizable monomer as described above, and it is also possible to combine these methods (1) and (2).

As mentioned above, an epoxy resin or a polyhydric phenol is required as a raw material for the vinyl ester resin used in the present invention. Since epoxy resins are generally synthesized by a condensation reaction of polyhydric phenols and epichlorohydrin, etc., the vinyl ester resin used in the present invention has a polyhydric phenol structure in the resin skeleton, and the crosslinked cured product has rigidity, heat resistance, and resistance. It has excellent solvent resistance and moisture resistance. As polyhydric phenol structures, bisphenol A type, novolac phenol type, halogenated hisphenol A type, halogenated novolac phenol type, talesol novolac type, etc. are known, among which, novolac phenol type, halogenated bisphenol A type, Halokenated novolak phenol type and the like are preferred because their cured products have excellent heat resistance, solvent resistance, and moisture resistance.

The above unsaturated polyester resin and vinyl ester resin used in the present invention are usually glass fiber, carbon fiber,
By impregnating reinforcing materials such as organic fibers and curing them,
This is used as an FRP molded product.

The present inventors focused on the excellent transparency of cured unsaturated polyester resin or vinyl ester resin alone without combining the above-mentioned reinforcing materials, and injected these liquid resins into a disc-shaped mold. The mixture was cured and demolded to obtain a hard disk with good transparency.

Furthermore, when a stamper having a guide groove or an information pit pattern was placed on at least one side of the mold and a cured plate was produced in the same manner, it was confirmed that the pattern was faithfully transferred onto the resulting disc. This is the heading that led to the present invention.

Although organic peroxides, thermal energy, active energy rays, etc. can be used as means for curing the resin used in the present invention, a method of curing at room temperature using an organic peroxide and a curing aid is preferable. It is.

Examples of organic peroxides that can be used in the present invention include methyl ethyl ketone peroxide, cumene hydroperoxide, benzoyl peroxide, and t-butyl perbenzoate. (manufactured by Nouri ■), etc. The above may be used alone or in combination of two or more.

Examples of the curing aid include metal soaps such as cobalt naphthenate and cobalt octylate, tertiary amines such as dimethylaniline and dimethylparatoluidine, and vanadium accelerators. These materials can be used alone or in combination of two or more.

Among these, combinations using methyl ethyl ketone peroxide, cumene hydroperoxide, L-butyl perbenzoate as the organic peroxide and cobalt naphthenate as the curing aid are particularly preferred.

The mixing ratio of the above-mentioned organic peroxide and curing aid to the liquid resin is effective in the range of 0.01 to 10% by weight based on the total amount of resin, particularly in the range of 0.1 to 5% by weight. Blending is preferable in terms of curing speed and the like.

If a liquid resin composition in which a curing agent consisting of the organic peroxide and curing aid described above is blended with an unsaturated polyester resin or vinyl ester resin is poured into a predetermined mold having a cavity with a thickness of about 11 mm, it can be heated at room temperature. Curing occurs, and the cured product can be removed from the mold.

By using a disk-shaped mold having a stamper having a guide groove or an information pit pattern on at least one side as a mold, a transparent substrate having the above-mentioned pattern transferred onto its surface can be obtained as an integrally molded product.

When curing and molding the above-mentioned liquid resin composition, it is preferable to incorporate a mold release agent into the resin in advance to facilitate demolding. As internally added mold release agents used in the field of FRP molding, fatty acids, metal soaps, waxes, phosphate esters, nonionic surfactants, etc. are known. Any material that does not impair the curing properties of the product or properties such as the transparency of the cured product can be used as appropriate.

On the other hand, the cured product cured at room temperature using the above-mentioned curing agent is useful as a transparent substrate for use in optical recording media. Heat treatment can also be performed for the purpose of improving properties such as hardness and hardness. The treatment temperature can be appropriately selected within the range of 60 to 200°C.

When the transparent substrate thus obtained has guide grooves, a thin film recording layer made of, for example, amorphous metal, tellurium alloy, metal oxide, organic dye, etc. is provided, and if necessary, a thin film recording layer made of aluminum, etc. An optical information recording medium can be constructed by providing a reflective layer, a protective layer, and a transparent resin layer. In addition, when the transparent substrate has an information pit pattern, a reflective layer made of aluminum or the like can be provided, and if necessary, a protective layer and a transparent resin layer can be provided to configure an optical information recording medium. .

〔Effect of the invention〕

The manufacturing method of the present invention provides the following advantages.

(11 In order to inject the liquid resin composition into the mold and harden it,
The molding distortion seen in conventional injection molded thermoplastic resin products is extremely small, and a substrate with little optical distortion can be obtained.

Furthermore, since the liquid resin composition is sufficiently filled into the fine patterns of the grooves or bits, the pattern transferability is excellent.

(2) Since the resin can be cured at room temperature, heat,
There is no need for large-scale equipment or transparent molds that are required when using light.

(3) By selecting the resin composition, it is possible to obtain a substrate with excellent heat resistance and solvent resistance, and the substrate is not attacked during the process of forming a thin film recording layer by vapor deposition of metals or solution coating of organic dyes. Hateful.

(4) The obtained transparent substrate does not absorb light in the wavelength region of 700 nm or more, and can be used for laser beams such as 780 nm or more.
It is suitable as an optical recording medium for recording and reading with a semiconductor laser of 830 nm or 830 nm. Furthermore, since it exhibits strong absorption in the ultraviolet wavelength region, it also has the advantage of preventing deterioration of the recording layer.

〔Example〕

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited only to these Examples.

Example 1 A bisphenol A type epoxy resin (DER661 manufactured by Dow Chemical Company) was reacted with methacrylic acid, and the product was dissolved in styrene monomer (amount of 45% by weight based on the total resin) at 25°C. A vinyl ester resin (resin A) having a viscosity of 320 cp was obtained. 100 parts by weight of resin A,
Polyoxyethylene stearyl ether (
0.3 parts by weight of Emulgen 320P (manufactured by Kao ■), 0.5 parts by weight of cobalt naphthenate (Naftex Co, manufactured by Nippon Kagaku Sangyo) as a hardening agent, and 1.0 parts by weight of hardening agent 328E (manufactured by Kayaku Nury ■). It was blended. This liquid resin composition was applied to a nickel stamper 2 having an outer diameter of 130 mm and having a guide groove pattern 7, as shown in FIG.
Then, as shown in FIG. 1(b), a flat glass plate 3 was placed over the liquid resin composition 1 so that the gap having a thickness of 1.2 mm was filled with the liquid resin composition 1.

If left as is at room temperature, the liquid resin will harden.
As shown in FIG. 1(C), the cured transparent plate 4 could be easily removed from the mold. The guide groove pattern 7 of the stamper was faithfully transferred to the surface of the cured transparent plate 4. 1st
As shown in Figure (d), a hole 6 with an inner diameter of 15 mm was made in the center of the cured transparent plate 4, and heat treatment was performed at 120° C. for 2 hours to obtain a transparent substrate 5.

Table 1 shows the characteristic values of the obtained transparent substrate.

Example 2 Novolak phenolic epoxy resin (DOW Chemical Company DEN 43B'') was reacted with methacrylic acid, the product was dissolved in styrene monomer (36% by weight based on the total resin) and heated at 25°C. The viscosity at is 280cp
A vinyl ester resin (resin B) was obtained. Resin B100
As in Example 1, 0.0% of cobalt naphthenate is added to the weight part.
5 parts by weight and 1.0 part by weight of hardening agent 328E were mixed, poured into a nickel stamper with an outer diameter of 120 mm and having an information pit pattern, cured at room temperature in the same manner as in Example 1, and then heated at 150°C for 1 hour. A transparent substrate was obtained by heat treatment. A thin aluminum film (reflection layer) of approximately 10 000 mm thick is provided on the surface of the transparent substrate onto which the information pit pattern has been transferred by vacuum evaporation, and an ultraviolet curing resin is applied on top of the aluminum layer to irradiate ultraviolet rays. Irradiate to a thickness of about 2
By providing a protective layer of 0.00, an optical disc could be manufactured.

Table 1 shows the characteristic values of the transparent substrate.

Example 3 Brominated epoxy resin (DER542 manufactured by Dow Chemical Company)
) with methacrylic acid and the product is dissolved in styrene monomer (40 wt% t based on total resin) to give 2
Vinyl ester resin with a viscosity of 290 cp at 5°C (
Resin C) was obtained. As in Example 1, 0.5 parts by weight of cobalt naphthenate and 3 parts by weight of curing agent were added to 100 parts by weight of resin C.
1.0 part by weight of 28E was blended. This liquid resin composition was cured and molded in the same manner as in Example 1, and heat treated at 150° C. for 1 hour to obtain a transparent substrate.

The characteristic values of this transparent substrate are shown in Table 1.

Example 4 100 parts by weight of bisphenol type unsaturated polyester resin (Nutrack 410 manufactured by Kao Corporation) was added with polyoxyethylene sorbitan monolaurate (Kao Corporation) as a mold release agent.
Rheodor TW-L106) 0.5 parts by weight, curing agents: 0.1 parts by weight of dimethylaniline, 0.5 parts by weight of cobalt naphthenate, methyl ethyl ketone peroxide (
0.8 parts by weight of Vermec N (manufactured by NOF Corporation) was blended.

This liquid resin composition was cured and molded in the same manner as in Example 1.
A transparent substrate was obtained by heat treatment at 50° C. for 1 hour.

The characteristic values of this transparent substrate are shown in Table 1.

Comparative Examples 1 and 2 For comparison, a polymethyl methacrylate resin (Comparative Example 1) and a polycarbonate resin (Comparative Example 2) were molded by normal injection molding, respectively, and a thickness of 1.5 mm with a guide groove pattern transferred on one side was obtained. A transparent substrate with a diameter of 2 mm and an outer diameter of 130 mm was obtained.

The characteristic values of these transparent substrates are also shown in Table 1.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a method for manufacturing a substrate for an optical information recording medium according to the present invention. 1... Liquid resin composition 2... Stamper 3... Flat plate 4... Cured transparent plate 5... Transparent substrate 6. ... Hole 7 ... Guide groove pattern

Claims (1)

[Claims] 1. An unsaturated polyester resin or vinyl ester resin composition that is liquid at room temperature and contains an organic peroxide and a curing aid is poured into a stamper having a matrix having a guide groove or information pit pattern. A method of manufacturing a substrate for an optical information recording medium, which comprises curing the substrate. 2. The method for manufacturing a substrate for an optical information recording medium according to claim 1, wherein the vinyl ester resin is a novolac type vinyl ester resin or a halogenated vinyl ester resin.