JPH04330650A - Production of substrate for optical disk - Google Patents

Abstract

PURPOSE:To increase the strength of adhesion between a substrate and a photosetting resin and to lower a defective generation rate by applying a UV curing type primer coating material contg. a prescribed compd. and photopolymn. initiator >=2 times by spin coating on the substrate and baking the coating after irradiation with UV rays. CONSTITUTION:A primer layer 2 is formed on the optically transparent glass substrate 1 and a 3P layer 3 having rugged patterns of guide grooves and/or signal pits consisting of a photosetting resin (2P resin) is formed thereon. The primer layer 2 is formed by applying the UV curing type primer coating material contg. alkoxysilane having a methacrylic group, acrylate and the photopolymn. initiator >=12 times by spin coating and baking the coating after the irradiation with the UV rays. The acrylate is used alone or by mixing >=2 kinds thereof. The compounding ratio of the alkoxysilane in the primer coating material is preferably in a 1 to 10wt.% range and the compounding ratio of the acrylate is preferably 80 to 9Owt.%. The compounding ratio of the photopolymn. initiator is preferably 1 to 10wt.%.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides 2P (Photo Polymerization) on an optically transparent substrate.
On) method, photo-curable resin (Photo Pol
ymer, hereinafter referred to as 2P resin. ) and/or a layer having a concavo-convex pattern such as signal pits (hereinafter referred to as 2P layer). The present invention relates to a method for manufacturing an optical disc substrate with excellent performance.

0002

[Prior Art] Three types of optical discs are known: read-only type, write-once type, and rewritable type.
Read-only and write-once optical discs are already used in various fields. The development of rewritable optical disks is also progressing rapidly, and magneto-optical disks in particular are about to enter the period of full-scale practical use. As substrate materials for these optical disks, thermoplastic resins such as polymethyl methacrylate and polycarbonate, thermosetting resins such as epoxy resins, or glass are generally used. In addition, it is particularly useful as a substrate material for magneto-optical disks due to its low birefringence and
Active research is also being conducted on new polyolefin resins that have the characteristic of low water absorption.

Nowadays, when it is necessary to transmit, process, and store a wide variety of enormous amounts of information, the performances required of optical disks as recording media are large capacity, high speed data transfer, and high reliability. The main focus of research is on these points. In order to achieve these advanced performances, the role played by the substrate material is extremely important.
In this sense, great expectations are placed on glass substrates.

[0004] For example, increasing capacity can be achieved by increasing the diameter of the substrate, but when the diameter of the polycarbonate substrate, which is currently most commonly used, is around 300 mm, mechanical properties such as surface runout deteriorate when the disk rotates. Therefore, it is difficult to support high-speed rotation (3,600 rpm or more). In addition, it is difficult to control injection molding conditions, and there are drawbacks such as increased birefringence distribution in the circumferential direction. In this respect, glass is a substrate material with the best mechanical properties and has no birefringence, so it is advantageous for increasing the diameter.

[0005] Furthermore, in order to speed up data transfer, research is being conducted to increase the disk rotation speed.
Recently, experiments have been conducted on high-speed recording of 5,000 rpm or more. In this respect as well, glass substrates have much better dynamic mechanical properties than other plastic substrates, and glass substrates can be said to be optimal for high rotational speed recording.

Furthermore, glass substrates are excellent in stability under high temperature and high humidity conditions, and are the most reliable substrate material.

[0007] Generally, an uneven pattern such as a guide groove for guiding a laser beam or a preformat signal pit is formed in advance on an optical disk substrate, but in the case of a glass substrate, an uneven pattern is formed using 2P resin. The 2P method is known.

However, even if the 2P resin, which is an organic material, is directly formed on the glass, which is an inorganic material, a large adhesion force cannot be obtained between the two, resulting in the following disadvantages. That is, during 2P molding, when the glass substrate is peeled off from the stamper (a molding die created by transferring from the master disk by electroforming), some or all of the cured 2P resin may remain on the stamper side. Alternatively, floats (an air layer formed between the glass substrate and the 2P layer) frequently occur in a part of the 2P layer formed on the glass substrate. Also, 2
Even if P is well formed during molding, cracks, wrinkles, and flakes will occur over time under high temperature and high humidity conditions.

In order to improve the above-mentioned drawbacks, various studies have been made to improve the adhesive strength between glass and 2P resin. The most widely known method among these studies is to form a coating film of a primer made by diluting various silane coupling agents with an organic solvent on a glass substrate, and the following examples have been reported in the past. has been done.

For example, JP-A-62-139150 discloses that by providing an aminosilane primer layer diluted with toluene between a glass substrate and an epoxy resin layer, the adhesive strength between the two is increased. It is shown.

[0011] Furthermore, JP-A No. 59-65953 discloses that a silane coupling agent having a boiling point of 200°C or higher and having an acrylic group or a methacrylic group is used, and an aromatic carbonization agent having a boiling point of 120 to 200°C is used. Hydrogen, ether type,
It has been shown that a primer diluted with at least one of ketone, ester, and polyhydric alcohol ester solvents and further added with an organic acid is effective.

Furthermore, JP-A-1-248335 discloses that a primer prepared by diluting ethene-based unsaturated silane with methyl alcohol is effective.

[0013]

[Problems to be Solved by the Invention] All of the conventional methods described above are effective to some extent in improving the adhesiveness between the glass substrate and the 2P resin. However, when continuous 2P molding is performed using a 2P resin that has excellent moldability, that is, good flowability (700 cps or less) and good peelability from the stamper after curing, floating may occur in some areas. , a checkerboard peel test using "Cellotape" (cellophane adhesive tape manufactured by Nichiban Co., Ltd.) (JIS, K540)
0, 8.52, species standard), defective products with a residual film rate ({total square area - peeling area} ÷ total square area) of 90% or less may be produced. These problems arise from insufficient initial adhesion between the glass substrate and the 2P resin. In addition, due to this weak initial adhesive strength, minute undulations occur in the 2P layer when it is peeled off from the stamper, so the axial acceleration exceeds the standard (20 m/s 2
) In some cases, defective products may occur.

Furthermore, even if the initial adhesive strength is good, cracks, wrinkles, and flakes may occur over time under high temperature and high humidity conditions (for example, 80° C. and 85% RH).

As described above, in the conventional method of performing primer treatment on the glass substrate, the glass substrate and the 2P
There was a problem in that the adhesive strength between the resin and the resin was insufficient, resulting in a high incidence of defective products during continuous molding.

The problem to be solved by the present invention is to provide an optical disk substrate in which a layer having a concavo-convex pattern such as guide grooves and/or preformat signal pits made of 2P resin is provided on an optically transparent substrate. This increases the adhesive strength between the substrate and the 2P resin, reduces the incidence of defective products during continuous molding using the 2P method, and increases the adhesive strength between the glass substrate and the 2P resin even under high temperature and high humidity. It is an object of the present invention to provide a method for manufacturing a highly reliable optical disk substrate that does not deteriorate.

[0017]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention forms a primer layer on an optically transparent substrate, and coats a photocurable resin (2
In the method for manufacturing an optical disk substrate, the primer layer forms a layer (2P layer) having a concavo-convex pattern of guide grooves and/or signal pits made of P resin), wherein the primer layer is made of alkoxysilane having a methacrylic group, an acrylic ester, and a light Provided is a method for producing a substrate for an optical disk, which is formed by spin-coating an ultraviolet curable primer coating containing a polymerization initiator on the substrate two or more times, irradiating it with ultraviolet rays, and then baking it. .

FIG. 1 is a sectional view of an optical disk substrate according to the present invention. In this figure, 1 is a disk-shaped glass substrate, 2 is a primer layer consisting of an ultraviolet curable primer coating containing an alkoxysilane having a methacrylic group, an acrylic acid ester, and a photopolymerization initiator, and 3 is a 2
It shows a layer (2P layer) in which a concavo-convex pattern such as guide grooves and/or signal pits made of 2P resin is formed by the P method.

Glass such as chemically strengthened soda lime glass or soda aluminosilicate glass is suitable for the glass substrate 1, and a disk-shaped glass is used.

[0020] The glass substrate is cleaned immediately before forming the primer layer 2 in order to remove organic matter or dust adhering to the surface. Effective cleaning methods include scrub cleaning in pure water and detergent, ultrapure water cleaning, etc. using a 4 to 8 continuous automatic cleaning device. By performing this cleaning, organic substances, dust, etc. on the surface of the glass substrate are removed.

Primer layer 2 is formed by spin-coating an ultraviolet curable primer paint containing an alkoxysilane having a methacrylic group, an acrylic acid ester, and a photopolymerization initiator two or more times, irradiating it with ultraviolet light, and then applying it at a temperature of 100 to 200°C. Formed by baking within a temperature range.

Examples of the acrylic ester used in the present invention include polyester acrylates such as propylene oxide adipic acrylic acid and diethylene glycol acrylic trimetate; epoxy acrylates such as bisphenol A epichlorohydrin acrylic acid and phenol novolak epichlorohydrin acrylic acid;
Urethane acrylates such as ethylene glycol adipate tolylene diisocyanate 2-hydroxyethyl acrylate, polyethylene glycol tolylene diisocyanate 2-hydroxyethyl acrylate; monofunctional acrylate monomers such as 2-hydroxyethyl acrylate, phenoxyethyl acrylate, nonylphenoxyethyl acrylate; diethylene glycol Diacrylate, neopentyl glycol diacrylate, 3
- Bifunctional acrylate monomers such as methylpentanediol diacrylate; trifunctional or higher functional acrylate monomers such as trimethylolpropane triacrylate, dipentaerythritol propionate tetraacrylate, dipentaerythritol hexaacrylate, and the like.

These acrylic esters can be used alone or in combination of two or more.

The blending ratio of alkoxysilane in the UV-curable primer paint is preferably in the range of 1 to 10% by weight, the blending ratio of acrylic ester is preferably in the range of 80 to 98% by weight, and the blending ratio of the photopolymerization initiator is preferably in the range of 80 to 98% by weight. The blending ratio is 1~
A range of 10% by weight is preferred.

[0025] Furthermore, an organic solvent may be added for the purpose of improving the fluidity of the primer constituent material.

The organic solvent that can be added to the material constituting the primer layer must be capable of forming a uniform solution and improving fluidity when mixed with the above-mentioned acrylic ester, such as toluene, xylene, Examples include aromatic hydrocarbons such as benzene; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and n-butyl acetate; alcohols such as ethyl alcohol and isopropyl alcohol. These organic solvents can be used alone or in combination of two or more.

[0027] The primer layer can be applied by spin coating,
Although known coating methods such as dipping and spraying methods can be used, spin coating is most suitable since it is highly mass-producible and can easily form a uniform coating film. Further, when forming a coating film by a spin coating method, the coating liquid can be dried by keeping the glass substrate rotating. By performing this spin coating two or more times in succession, a uniform primer layer is formed on the surface of the glass substrate, and unevenness in the adhesive force of the 2P resin layer 3 to the glass is eliminated. As a result, the incidence of defective products during continuous molding using the 2P method is greatly reduced compared to when spin coating is performed only once.

The primer constituent material is applied, dried (spin dried) at room temperature and humidity, irradiated with ultraviolet rays to harden the acrylic ester, and then baked. The baking is preferably carried out in air at 100 to 200°C for about 10 to 60 minutes. If this baking is performed before the coating has dried to some extent at room temperature and humidity, the coating solution will rapidly rise in temperature and evaporate, resulting in a non-uniform primer layer.

The 2P layer 3 made of 2P resin is formed by the following process using the 2P method. That is, liquid 2P resin is placed on a stamper (a molding die made by transferring from a master disk by electroforming) on which a concavo-convex pattern such as a guide groove for guiding a laser beam or a preformat signal pit is formed. The glass substrate 1 is placed so that the surface on which the primer layer 2 made of a silane coupling agent is formed faces the stamper side, and the uncured 2P is applied with pressure.
2. Spread the resin and irradiate it with ultraviolet light from the glass substrate side.
After the P resin is cured, it is peeled off from the stamper to form a 2P layer 3 having a desired uneven pattern.

2 used when forming the 2P layer of the present invention
Examples of the P resin include, for example, a photo-radical polymerization composition containing a photo-radical polymerizable prepolymer, a monomer, and a photo-radical polymerization initiator as main components; A composition that is cured by ultraviolet light, such as a photo-cationic polymerization composition as a main component; a composition that is a mixture of a photo-radical polymerization composition and a photo-cationic polymerization composition; As long as it has good pattern transferability and moist heat resistance, it can be used without any particular restrictions.

[0031]

EXAMPLES The present invention will be explained in more detail below using Examples and Comparative Examples.

(Example 1) First, a soda aluminosilicate glass substrate with an outer diameter of 130 mm, an inner diameter of 15 mm, and a thickness of 1.1 mm was scrub-cleaned in pure water and detergent using a five-coat automatic cleaning device. Organic substances and dust on the surface of the glass substrate were removed by ultrasonic cleaning in ultrapure water.

Within 30 minutes after washing, 3.0% by weight of γ-methacryloxypropyltrimethoxysilane, 40% by weight of 1,6-hexanediol diacrylate, and 30% by weight of 2-hydroxy-3-phenoxypropyl acrylate.
A primer paint consisting of 25.0% by weight of xylene and 2.0% by weight of hydroxycyclohexylphenyl ketone was applied onto a glass substrate by a spin coating method to prepare the following (1):
Coating was carried out by changing the rotational speed in two stages as in (2).

(Spin coating conditions) (1) Low speed rotation: 60 rpm, 14 seconds (primer application: 10 seconds) (2) High speed rotation: 2,800 rpm, 30 seconds
seconds

[0035] Repeating the above (1) and (2) twice,
After the primer coating was applied and dried, the primer layer was cured by irradiating ultraviolet light at 30 mW/cm2 for 20 seconds. Then, in a clean oven at 100℃,
I baked it for 1 hour.

[0036] Primer layer formed by the above method 2
A 2P resin layer was formed on the primer layer forming surface of 00 glass substrates by continuous molding using a 2P molding machine (manufactured by Dainippon Ink & Chemicals Co., Ltd.). In this case, "STM-401" (Dainippon Ink & Chemicals Co., Ltd.) is used as the 2P resin.
Co., Ltd.) was used.

All 50 glass substrates were in good molding condition, and during 2P molding, when the glass substrates were peeled off from the stamper, no part or all of the cured 2P resin remained on the stamper side. Also, a part of the 2P layer formed on the glass substrate is floating (glass substrate and 2P layer).
There was no formation of air spaces between the layers.

In order to evaluate the initial adhesion between the 2P resin layer and the glass substrate, a cross-cut peeling test (JIS, D-202, 8.121 type standard) using "cellotape" was conducted, and a total of 50 sheets were tested. The remaining film rate was 100% for all glass substrates.

Furthermore, even after a heat and humidity test at 80° C., 85% RH, for 2,000 hours, the remaining film rate was 100% on all 50 glass substrates, and there were no cracks or cracks in the 2P resin layer.
No wrinkles or flakes were observed.

(Example 2) A primer layer and a 2P resin layer were formed on a glass substrate in the same manner as in Example 1, except that soda lime glass was used instead of soda aluminosilicate glass in Example 1. As a result, all 50 glass substrates were in good molding condition.

As a result of carrying out a checkerboard peeling test in the same manner as in Example 1, the remaining film rate was 1 for all 50 glass substrates.
It was 00%. Also, 80℃, 85%RH, 2,000℃
The results of the cross-cut peeling test after the 0-hour heat and humidity test were as follows: 48 sheets had a residual film rate of 100%, and 2 sheets had a residual film rate of 90% or more1.
00, and no cracks, wrinkles, or flakes were observed in the 2P resin layer on any of the substrates.

(Comparative Example 1) A primer layer and a 2P resin layer were formed on a glass substrate in the same manner as in Example 1 except that the number of times the primer paint was applied was changed to one time. As a result, 50 sheets All of the glass substrates were molded in good condition, and during 2P molding, when the glass substrate was peeled off from the stamper, part or all of the cured 2P resin did not remain on the stamper side, and there was no residue on the glass substrate. Floating on a part of the formed 2P layer (glass substrate and 2P layer)
There was no formation of air spaces between the layers.

In order to evaluate the initial adhesive strength between the 2P resin layer and the glass substrate, a checkerboard peel test was conducted in the same manner as in Example 1. As a result, 22 sheets had a residual film rate of 100%, and 21 sheets had a residual film rate of 100%. 90% or more and less than 100%, 7 sheets have a residual film rate of 80% or more 9
It was less than 0%.

[0044] Also, the results of the cross-cut peeling test after the heat and humidity test at 80°C, 85% RH for 2,000 hours were 3.
8 sheets have a residual film rate of 90% or more and less than 100%, 11 sheets have a residual film rate of 80% or more and less than 90%, and 1 sheet has a residual film rate of 60% or more and 70%.
%. Furthermore, on 18 substrates, the occurrence of flaking was observed in the 2P resin layer.

(Comparative Example 2) In Comparative Example 1, 3.0% by weight of γ-methacryloxypropyltrimethoxysilane,
A primer layer and a 2P resin layer were formed on a glass substrate in the same manner as in Comparative Example 1, except that a primer paint consisting of 97.0% by weight of toluene was used and 20 glass substrates were used. Among the glass substrates, 11 were in good molding condition, and in 9 glass substrates, when they were peeled off from the stamper during 2P molding, a part of the hardened 2P resin remained on the stamper side.

In order to evaluate the initial adhesive strength between the 2P resin layer and the glass substrate, a grid peel test was conducted in the same manner as in Example 1. As a result, the remaining film rate was 2 for all 20 glass substrates.
It was 0% or less.

(Comparative Example 3) In Comparative Example 1, 2.0% by weight of γ-methacryloxypropyltrimethoxysilane,
A primer layer and 2P were formed on a glass substrate in the same manner as in Comparative Example 1, except that a primer paint consisting of 98.0% by weight of n-butyl acetate was used and 20 glass substrates were used.
As a result of forming the resin layer, 13 of the 20 glass substrates had good molding conditions, and 7 glass substrates had good molding conditions.
When peeling off from the stamper during 2P molding, the hardened 2P
Some of the resin remained on the stamper side.

In order to evaluate the initial adhesive strength between the 2P resin layer and the glass substrate, a grid peel test was conducted in the same manner as in Example 1. As a result, the residual film rate was 2 for all 20 glass substrates.
It was 0% or less.

(Comparative Example 4) In Comparative Example 1, N-β(
A primer layer and a 2P resin layer were formed on a glass substrate in the same manner as in Comparative Example 1, except that a primer paint consisting of 2.0% by weight of γ-aminopropyltrimethoxysilane and 98.0% by weight of ethyl alcohol was used. As a result, out of 50 glass substrates, 42 were in good molding condition, and 8 glass substrates had some of the hardened 2P resin on the stamper when peeled off from the stamper during 2P molding. I remained on the side.

In order to evaluate the initial adhesive strength between the 2P resin layer and the glass substrate, a grid peel test was conducted in the same manner as in Example 1. As a result, 8 sheets had a residual film rate of 80% or more and less than 90%, 1
0 sheets have a residual film rate of 70% or more and less than 80%, 32 sheets have a residual film rate of 7
It was less than 0%.

[0051] Furthermore, as a result of the cross-cut peel test after the heat and humidity test at 80°C, 85% RH, for 2,000 hours, the residual film rate was 50% or less for all 50 glass substrates. Furthermore, in 32 substrates, the occurrence of flaking was observed in the 2P resin layer.

(Comparative Example 5) Same as Example 1 except that a primer paint consisting of a mixed solution of 2.0% by weight of γ-aminopropyltriethoxysilane and 98.0% by weight of ethyl alcohol was used. As a result of forming a primer layer and a 2P resin layer on a glass substrate,
Among the glass substrates, 40 were in good molding condition, and on 10 glass substrates, when they were peeled off from the stamper during 2P molding, some of the hardened 2P resin remained on the stamper side. .

In order to evaluate the initial adhesion between the 2P resin layer and the glass substrate, a checkerboard peel test was conducted in the same manner as in Example 1. As a result, 6 sheets had a residual film rate of 80% or more and less than 90%, 1
0 sheets have a residual film rate of 70% or more and less than 80%, 34 sheets have a residual film rate of 7
It was less than 0%.

[0054] Furthermore, the results of the cross-cut peel test after the heat and humidity test at 80°C, 85% RH for 2,000 hours showed that the remaining film rate was 50% or less for all 50 glass substrates. Furthermore, on 38 substrates, the occurrence of flaking was observed in the 2P resin layer.

(Comparative Example 6) In Comparative Example 1, a primer paint consisting of 2.0% by weight of γ-glycidoxypropyltrimethoxysilane and 98.0% by weight of ethyl alcohol was used, and 20 glass substrates were used. A primer layer and 2P were formed on a glass substrate in the same manner as in Comparative Example 1, except that
As a result of forming the resin layer, 6 out of 20 glass substrates had a good molding condition, and 14 glass substrates had a good molding condition.
When peeling off from the stamper during 2P molding, the hardened 2P
Some of the resin remained on the stamper side.

In order to evaluate the initial adhesive strength between the 2P resin layer and the glass substrate, a grid peel test was conducted in the same manner as in Example 1. As a result, the remaining film rate was 2 for all 20 glass substrates.
It was 0% or less.

(Comparative Example 7) Comparative Example 1 except that a primer paint consisting of 2.0% by weight of γ-mercaptopropyltrimethoxysilane and 98.0% by weight of methyl alcohol was used, and 20 glass substrates were used. As a result of forming a primer layer and a 2P resin layer on a glass substrate in the same manner as in Comparative Example 1, 6 out of 20 glass substrates had a good molding condition, and 14 glass substrates had a good molding condition. ,2
When peeling off from the stamper during P molding, a portion of the cured 2P resin remained on the stamper side.

In order to evaluate the initial adhesive strength between the 2P resin layer and the glass substrate, a grid peel test was conducted in the same manner as in Example 1. As a result, the remaining film rate was 2 for all 50 glass substrates.
It was 0% or less.

(Comparative Example 8) Outer diameter 130 mm, inner diameter 15 m
A soda aluminosilicate glass substrate with a thickness of 1.1 mm was subjected to scrub cleaning in pure water and detergent and ultrasonic cleaning in ultrapure water using a 5-row automatic cleaning device. Organic substances and dust on the surface of the glass substrate were removed.

Within 30 minutes after washing, as a 2P resin,
STM-401'' (manufactured by Dainippon Ink and Chemicals, Ltd.) using a 2P molding machine (manufactured by Dainippon Ink and Chemicals)
As a result of continuous molding of 10 sheets using
Most of the P resin remained on the stamper side.

[0061]

[Effects of the Invention] According to the manufacturing method of the present invention, the adhesive strength between the glass substrate and the 2P resin is increased, and the incidence of defective products during continuous molding of the 2P method is reduced. Also, it is possible to provide a highly reliable optical disc substrate in which the adhesive strength between the glass substrate and the 2P resin does not decrease.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic structure of an optical disk substrate according to the present invention.

[Explanation of symbols] 1 Glass substrate 2 Primer layer 3 2P layer

Claims (2)

[Claims] Claim 1: An optical disc for use in which a primer layer is formed on an optically transparent substrate, and a layer having an uneven pattern of guide grooves and/or signal pits made of a photocurable resin is formed on the primer layer. In the method for manufacturing a substrate, the primer layer is formed by spin-coating an ultraviolet curable primer paint containing an alkoxysilane having a methacrylic group, an acrylic acid ester, and a photopolymerization initiator on the substrate two or more times and irradiating it with ultraviolet rays. A method of manufacturing an optical disc substrate, characterized in that the substrate is formed by performing baking. [Claim 2] The content of alkoxysilane having a methacrylic group in the UV-curable primer paint is 1 to 10.
% by weight, and the content of acrylic ester is 8
Claim 1 characterized in that the content of the photopolymerization initiator is in the range of 0 to 98% by weight, and the content of the photopolymerization initiator is in the range of 1 to 10% by weight.
The method for manufacturing the optical disc substrate described above.