JPH01248335A - Substrate for optical recording medium and its production - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of a glass substrate and a curable resin which forms guide grooves and/or signal pits and to prevent optical defects by interposing an unsatd. silane film of an ethene system between the glass substrate and the curable resin layer. CONSTITUTION:This substrate is constituted by interposing the thin film 3 of the coupling agent consisting of the unsatd. silane of the ethene system between the glass substrate 1 and the curable resin layer 5 formed with the guide grooves and/or the signal pits. The substrate surface is subjected to UV/O3 cleaning and/or plasma cleaning, etc., to decompose away the org. matter sticking thereto before the treatment with the silane coupling agent so that OH groups are formed on the glass surface. The resin consisting of the compsn. composed of a prepolymer component, a monomer component as a reactive diluent and a photopolymn. initiator component is used as the curing type resin. The adhesiveness of the glass substrate and the curable resin layer is thereby improved and the generation of the optical defects is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium base capable of recording/reproducing only reproduction or erasing/recording/reproducing using a light beam, and a method for manufacturing the same. For more details, please refer to 2P (
The present invention relates to an optical recording medium substrate in which guide grooves and/or signal pits for preformat signals are formed by a method called a photo polymerization method, and a method for manufacturing the same.

[Conventional technology]

2P (Photo Polymerization
) method, as described in Japanese Patent Publication No. 61-29053, etc., uses a glass substrate, and the surface of the substrate that is to be in contact with a hardening resin layer forming guide grooves and/or signal pits of preformat signals. Moreover, it is said that by performing a silane coupling agent treatment as a pretreatment, the glass substrate and the hard/soft resin layer can be bonded well.

Also, as described in Japanese Patent Application Laid-Open No. 61-29053,
After UV/O3 cleaning treatment is applied to the glass substrate 2, a silane coupling agent treatment is performed using hexamethyldisilazane as a silane coupling agent, and then a photoresist film is formed on the hexamethyldisilazane film. It is said that when formed, the adhesion between the glass substrate and the photoresist film is improved.

[Problem that the invention is trying to solve] However,
In the above-mentioned 2P method, when performing silane coupling agent treatment to provide a silane coupling agent layer between the glass substrate and the curable resin layer, the silane coupling agent on the glass substrate surface and the glass substrate surface are If the reaction occurs uniformly, partial adhesion failure between the glass substrate and the silane coupling agent layer may occur.

As a result, the 2P layer (curable resin layer) does not adhere uniformly to the glass substrate, causing defects in appearance, which cause optical defects in the substrate for optical recording media. Furthermore, since a uniform silane coupling agent layer is not formed on the surface of the glass substrate, there is a problem in that uneven coating of the 2P layer occurs and the thickness of the 2P layer becomes highly uneven. Also,
The adhesion between the glass substrate and the 2P layer was also insufficient, and there was a problem in that the 2P layer peeled off from the glass substrate in an environmental durability test.

In addition, after performing UV/O3 cleaning treatment on the glass substrate,
Even if a hexamethyldisilazane film is formed using hexamethyldisilazane as a silane coupling agent, and a curable resin guide groove and preformat signal are formed on this film by the 2P method, the glass substrate and the 2P layer The adhesion was not sufficient, and there was a problem that the 2P layer peeled off from the glass substrate during an environmental durability test.

In addition, the optical recording medium in which a recording layer and a protective layer were formed on the 2P layer was subjected to an environmental durability test (70°C, 185%RH).

5.000) There was a problem in that recording characteristics deteriorated after being left for a period of time. In particular, when a magnetic recording layer is used as the recording layer, there is a problem that the C/N and recording sensitivity change compared to the initial state. Furthermore, if a film with high stress is formed as a recording layer and a protective layer on the 2P layer, the 2P layer will soften due to the rise in substrate temperature during film formation, and even if the film is formed while preventing the rise in substrate temperature, Due to the stress of the film formed on the 2P layer, external defects such as cracks or blisters occurred in the 2P layer after the environmental durability test.

An object of the present invention is to solve the above-mentioned problems and provide a base for an optical recording medium that has excellent adhesion between a glass substrate and a curable resin layer forming guide grooves and/or signal pits, and a method for manufacturing the same. It's about doing.

[Means for solving problems]

The above-mentioned object of the present invention is to first apply UV/O3 to the surface of the substrate when producing a substrate for an optical recording medium by providing guide grooves and/or signal pits made of curable resin on the substrate using the 2P method.
This is accomplished by performing cleaning and/or plasma cleaning, then applying ethene-based unsaturated silane, and finally forming guide grooves and/or signal pits made of a curable resin on the coating film. Moreover, as this curable resin, (A)1
0 to 50% by weight polyurethane acrylate or polycarbonate acrylate, (B) 10 to 80% by weight acrylic ester having the following structure, and (C) 1
．． One containing 0 to 4.0% by weight of a photopolymerization initiator and having two acryloyl groups or methacryloyl groups is used.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

According to the present invention, in the method of manufacturing a substrate using the 2P method, a transparent glass substrate such as chemically strengthened glass or blue glass is used as the substrate, and the surface of the substrate is Cleaning and/or plasma cleaning is performed to decompose and remove organic matter adhering to the surface of the glass substrate, and to form ○I (groups) on the glass surface.
. The degree of UV/O3 cleaning and plasma cleaning is preferably such that the contact angle of water on the glass surface is 00.

Here, as the UV lamp used for U103 cleaning, a low pressure mercury lamp having a UV wavelength in the range of 300 nm is used. Examples of the silane coupling agent include ethene-based unsaturated silane, mercaptosilane, aminosilane, epoxysilane, and hexamethyldisilazane. The curable resin includes a prepolymer component (A), a monomer component (B) as a reactive diluent, and a photopolymerization initiator component (C).
Component (A) includes:
Polyol polyacrylate-1 (polyhydric alcohol or polyether polyol acrylate), especially trifunctional or higher functional polyol polyacrylate (pentaerythritol triacrylate, dipene querrythritol, hexaacrylate, etc.), modified polyol polyacrylate, polyhydric Diacrylates of modified diols made by adding epoxide to bisphenol A and bisphenol S, polyester acrylates (polyhydric alcohols, polybasic acids or their anhydrides, and acrylic acid c)
ondensation telomerizato
n), urethane acrylates (products made by reacting polyols such as polyether polyols and polyester polyols with polyisocyanates and acrylates with hydroxy groups), epoxy acrylates (products with acrylic acid or terminal carboxyl groups in the epoxy compound) (oligomer obtained by addition reaction of acrylate), bisphenol A siglycidyl ether type, novolac glycidyl ether type, epoxidized oil or fat, epoxidized butadiene, fatty acid-modified epoxy resin, or polycarbonate acrylate (polycarbonate polyol and acrylate with hydroxyl group) (obtained by reacting), etc. are used. (B) As the component,
Acrylic esters of polyhydric alcohols are used, and monofunctional acrylic monomers include cyclohexyl acrylate, benzyl acrylate-1-, carpitol acrylate, 2-ethylhexyl acrylate-1, lauryl acrylate, 2- Hydroxy-ethyl acrylate, glycidyl acrylate, dicyclopentadiene ethoxy acrylate, isobornyl acrylate, hydrogenated dicyclopentadiene acrylate, dicyclopentene-acrylate, and the like. Examples of polyfunctional acrylic monomers include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, butylene glycol diacrylate, neopentyl glycol diacrylate, and 1,4-butane. -Diacrylates such as diol diacrylate, 1,4-hexanediol diacrylate, 1,6-hexanediol diacrylate, and pentaerythritol diacrylate; and triacrylates such as pentaerythritol triacrylate and trimethylolpropane triacrylate. It will be done. As an allylic polyfunctional monomer,
Examples include diallyl phthalate, diallyl isophthalate, diallyl chlorenda-1., diallyl adipate, diallyl glycolate, triallyl cyanurate, diethylene glycol-bisallyl carbonate, and the like. (B
) The component may be one kind or a mixture of two or more kinds thereof.

As component (C), any known photopolymerization initiator can be used, but those with good storage stability after blending are desirable. For example, benzoin alkyl ethers such as benzoin ethyl ether and benzoin butiether, 2,
Acetophenones such as 2'-jetoxyacetophenone, 4'-phenoxy-2,2-dichloroacetophenone, 2-hydroxy-2-methylpropiophenone, 4'-isopropyl-2-hydroxy-2-methylpropiophenone, etc. Examples include propiophenone series, benzyl methyl ketal, 1-hydroxycyclohexylphenyl ketone, anthraquinone series such as 2-ethylanthraquinone and 2-chloroanthraquinone, and thioxanthone series such as 2,4-dimethylthioxanthone and Michler's ketone. These can be used alone or in a mixture of two or more in any proportion.

As a result of analyzing and investigating the causes of C/N and sensitivity reduction after environmental durability tests of optical recording media, we found that the uncured monomer (B) component, the photopolymerization initiator (C) component, and the photopolymerization initiator (C) component in the 2P resin cured product (C) Volatilization of low molecular weight substances such as aldehydes such as benzaldehyde and acetaldehyde, ketones such as hexyl phenyl ketone and acetone, and alcohols such as pendylalcoholne and methanol into the recording layer as decomposition products of component (C). , was found to be diffuse. In particular, as a recording layer, TbCo, GclTbFe, TbFeCo, G
dTbFeC.

using an amorphous magnetic recording layer such as SiN as a protective layer.

In the case of a magneto-optical recording medium in which a laminated film of one or a combination of two of SiOx, ZnS, SiC, etc. is formed on the 2P resin layer by vacuum evaporation or sputtering,
It has been found that the Curie temperature of the magnetic recording layer increases by 15 to 20°C due to the volatilization and diffusion of the low molecular weight substance into the recording layer, and that this changes the C/N recording sensitivity. From this result, the present inventors found that it is sufficient to use a 2P resin containing less low molecular weight substances that volatilize and diffuse. That is, from a study of the 2P resin properties, it is sufficient to use a 2P resin cured product having a heating loss start temperature of 150° C. or higher.

Furthermore, as a result of intensive research into the relationship between the characteristics of 2P resin and the occurrence of cracks in the 2P layer during film formation, and the occurrence of external defects such as cracks or blisters after environmental durability tests, we found that This means that blistering will not occur if a 2P resin with a high glass transition temperature (Tg) of 130°C or higher is used for the cured product.
It was found that this was due to partial swelling due to water absorption of the cured product, and it was found that the above-mentioned defect does not occur if a cured product with a water absorption rate of 1% or less is used.

In the present invention, we have discovered the above-mentioned curable resin composition as a 2P resin based on these facts.

The acrylic ester (B) having the following structural formula used in the present invention is
As described in No. 202112, it is obtained by reacting a compound obtained by condensing trimethylolpropane and 2,2-dimethyl-3-oxypropanal with acrylic acid.

In the curable resin composition of the present invention, in addition to component (B) as a monomer component, specific examples of monomers with low hydrophilicity include dicyclopentadiene ethoxy mono(meth)acrylate, isobornyl(meth)acrylate,
Hydrogenated dicyclopentadiene mono(meth)acrylate, 2,2-his(4-(meth)acryloyloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxyethoxyphenyl)methane, 2 ，
Contains (meth)acrylate monomers such as 2-bis(4-(meth)acryloyloxypropoxyphenyl)propane and trimethylolpropane tri(meth)acrylate, and a mixed system of one or more of these and component (B) can be used. The ratio of the components (A) and (B) in the curable resin composition of the present invention is determined by the T of the cured product.
Since it is desirable that g is 130'C or more and the water absorption rate is 1% or less, component (A) is 10 to 50% by weight.
%, component (B)] is preferably 0 to 80%. (
The proportion of component C) used is preferably in the range of 0.5% by weight to 3% by weight in view of the curability of the composition. That is,
If component (C) is less than 0.5%, the curing of the composition will be insufficient, and if it is more than 3%, the amount of component (C) remaining in the cured product will be large, which will volatilize and diffuse, adversely affecting the recording layer. I don't like it.

If an optical recording medium is made from the optical recording medium substrate using the above-mentioned curable resin, the C/N after the environmental durability test,
It was possible to reduce the decrease in recording sensitivity. Also, it was possible to eliminate appearance defects such as cracks and blisters.

In completing the present invention, in order to eliminate poor adhesion between the curable resin of the present invention and the glass substrate and optical defects due to uneven coating of the resin, the surface of the glass substrate was subjected to UV103 cleaning, plasma cleaning, etc. , we investigated silane coupling agent treatment. As a result, when manufacturing an optical recording medium substrate using the curable resin of the present invention,
It has been found that ethene-based unsaturated silanes (methacryloalkylsilane, vinylsilane) can be used. With mercaptosilane, aminosilane, epoxysilane, hexamethylsilazane, etc., sufficient characteristics could not be obtained due to the adhesion between the glass substrate and the 2P layer and the occurrence of optical defects due to uneven coating of the resin.

That is, when an optical recording medium was prepared using the optical recording medium substrate manufactured by the method of the present invention, there was no occurrence of peeling between the substrate and the 2P layer and no optical defects after the environmental durability test.

Hereinafter, the present invention will be explained in more detail with reference to specific examples.

As a real special board, outer circumference φ130, circumference φ15, thickness 1.1m
UV103 cleaning treatment 2 (low-pressure mercury lamp 4.5
The conditions were 0 W/cm, irradiation distance 25 mm, irradiation for 1 minute, and UV103 (254 nm light illuminance, 80 m W/cm rtr) on the substrate surface). Thereafter, within 1 hour, a coating solution containing methacryloxyalkylsilane A-174 (Nippon Unicar Co., Ltd.), an edene-based unsaturated silane, mixed with methanol (methanol: silane coupling agent -99.5: 0.5) was applied. Then, a methacryloxyalkylsilane film 3 with a thickness of 100 mm was formed on a glass substrate by spin cording (main rotation 2,0 OOr, p, m for 20 seconds) as shown in Fig. 2. Thereafter, at 110°C. 3
Heat drying treatment was performed for 0 minutes. Next, as shown in FIG. 3, (A) polyurethane acrylic resin 1-(NK Ester U-108A (Shin Nakamura Chemical Co., Ltd. bifunctional) 30 wt%, (B) acrylic ester [Kayarad R-604 (manufactured by Nippon Kayaku ■)] 667 wt% and (C)
A mixture of 33 wt of photopolymerization initiator [Irgacure 184 (manufactured by Nippon Ciba Gaiki ■)] was applied. The substrate is placed thereon so that the silane coupling agent-treated surface and the curable resin are in contact with each other, and the wavelength 365
The ultraviolet curable resin was cured by irradiating it with UV light of 100 nm wavelength at a UV intensity of 233 mw/crrr for 1 minute. after that,
As shown in FIG. 4, the substrate was peeled off from the stamper to create a base on which guide grooves 7 made of ultraviolet curable resin and signal pits for preformat signals were formed on the glass substrate.

K51'' Curing resin is made of (A) polycarbonate acrylate [
Artreshin UN-9000 (Itagami Kogyo@)) 30wt
%, (B) Acrylic ester [Kayarad R-604
(Nippon Kayaku Co., Ltd.) 67wt% and (C) photopolymerization initiator [Irukacure 184 (Nihon Kayaku ■)] 33
A base plate on which the resin guide grooves were formed was prepared in the same manner as in Example 1, except that the wt mixture was used.

A substrate was prepared in the same manner as in Examples 1 and 2, except that the vinyl silane agent A-171 (Nippon Unicar Co., Ltd.) was used as the ethene-based unsaturated silane.

5-8 The surface of the glass substrate to be treated with a silane coupling agent is
Instead of V103 cleaning treatment, plasma cleaning treatment (0
Input gas: 0.7 Pa, high frequency input power: 500 W.

The substrates were prepared in the same manner as in Examples 1 to 4, except that the test was carried out for 15 minutes.

As the 2P resin, (A) polyurethane acrylate (C
-9504 (manufactured by Sartomer) 30 wt%,
(B) Acrylic acid ester [Kayarad R-604 (manufactured by Nippon Kayaku ■) 40wt%, (C) dicyclopentanyl acrylate (FA-513A (manufactured by Hitachi Chemical ■)] 27w
A substrate was prepared in the same manner as in Example 1, except that a mixture of 3 wt % and (D) photopolymerization initiator [Irgacure 184 (manufactured by Nippon Ciba Geigy)] was used.

Support 1 fertilizer I 2P resin as (A) polycarbonate acrylate [Art Resin UN-9000 (Nedo Kogyo (Shiki))] 22
5wt% (B) Acrylic ester [Kayarad R-6
04 (manufactured by Nippon Kayaku ■) 55 wt%, (C) isobornyl acrylate (SR-506 (manufactured by Sartomer)) 11
7wt% (D) Photopolymerization initiator [Irgacure 184 (
A substrate was prepared in the same manner as in Example 1, except that a 3 wt % mixture of Nippon Ciba Geigy ■)'1 was used.

Hexamethyldisilazane (as a silane coupling agent)
A base was created in the same manner as in Example 1, except that product name: HMDS, Nippon Unicar Co., Ltd. was used.

A substrate was prepared in the same manner as in Examples 1 to 4, except that the surface of the glass substrate was not subjected to UV/O3 cleaning or plasma cleaning treatment before being treated with the silane coupling agent.

Bunkyo 1” Epoxysilane A-18 as a silane coupling agent
A base was created in the same manner as in Example 1 except that Nippon Unicar Co., Ltd. (stock system) was used.

Aminosilane A-112 was used as a silane coupling agent for comparison.
A substrate was prepared in the same manner as in Example 1 except that 0 (manufactured by Nippon Unicar Co., Ltd.) was used.

Mercaptosilane A-1 as a silane coupling agent
A substrate was prepared in the same manner as in Example 1 except that 89 (manufactured by Nippon Unicar Co., Ltd.) was used.

As a secondary silane coupling agent, chlorsilane A-143
(A base was created in the same manner as in Example 1 except that Nippon Unicar Co., Ltd. (stock system) was used.

3. As a 2P resin, (A) Epoxy acrylate [Viscoat #540 (Osaka Organic Chemical Industry Co., Ltd.) 60 wt%, (
B) 1,6-hexanethiol diacrylate [HDD
A substrate was prepared in the same manner as in Example 1, except that a mixture of 36 wt % A (Nippon Kayaku Co., Ltd.) and 4 wt % photopolymerization initiator (DAROCURE 1173 (manufactured by Merck)) was used.

Example 1: As a 2P resin, (A) PETA (mixture of pentaerythreed triacrylate and pentaerythritol tetraacrylate (manufactured by Osaka Organic Chemical Industry) 45 wt%
, (B) neopentyl glycol diacrylate CN
PGD'A (manufactured by Nippon Kayaku ■) 50 wt% and (C) photopolymerization initiator [Darocure 1173 (manufactured by Merck & Co., Ltd.):]
A substrate was prepared in the same manner as in Example 1 except that a 55 wt mixture was used.

In order to evaluate the adhesion between the substrate and 2P of these samples,
A board test (JIS5400) was conducted. As a result, Examples 1 to 10 had an evaluation score of 10, indicating good adhesion. Further, when Comparative Examples 1 to 11 were similarly evaluated for adhesion between the substrate and the 2P layer, the evaluation score was 2, indicating that the adhesion was not good. The contact angle of water on the substrate surface of Comparative Examples 2 to 5 was 20
~300 In Examples 1 to 10, organic matter adhering to the substrate surface was decomposed and removed by UV/O3/plasma cleaning treatment, and the contact angle of water on the substrate surface was 7 to 8.
° It was.

Next, a magneto-optical recording film (materials Gd, Tb, Fe) was formed on the substrates prepared in Examples 1 to 10 and Comparative Example 11.

Co) was formed by sputtering (to a thickness of 800 mm) to create a magneto-optical recording medium. Environmental durability test (7
After heating at 5° C., 980% RH for 2,000 hours, peeling between the glass substrate and the 2P layer was evaluated. As a result, there was no peeling of the 2P layer in the substrates of Examples 1 to 10, but in Comparative Example 1
In the substrates No. 1 to 11, peeling occurred between the substrate and the 2P layer.

If a substrate for an optical recording medium is produced according to the present invention as described above, the glass substrate and the 2P layer will be firmly adhered to each other.

In addition, we conducted an environmental durability test (75°C, 180°C) for magneto-optical recording media.
% R9H, 5,000 hours), the results of measuring C/N, recording sensitivity, and the occurrence of external defects such as cracks and blisters were summarized with a focus on the characteristics of the curable resin used. The items are shown in Table-1.

The C/N and recording sensitivity were measured using a magneto-optical information recording and reproducing device, recording and reproducing a 3 M I-T z signal. The recording sensitivity was measured by measuring the laser power required to obtain a C/N of 40 dB or more.

As is clear from Table 1, if a magneto-optical recording medium is made using the optical media substrate of the present invention, there will be almost no change in C/N and recording sensitivity even under the conditions of the environmental durability test. No cracks or blisters occurred during environmental durability tests, and the product had a good appearance and maintained long-term reliability.

The 2P resin properties were measured in the following manner.

1) The glass transition temperature Tg ('C) was determined by dynamic viscoelasticity measurement.

2) Water absorption was determined by leaving the cured 2P resin in water at 25°C for 20 days, and measuring the water absorption of the cured 2P resin from the difference in weight before and after.

3) The heating loss start temperature is measured using a thermal analyzer (TG-DSC).
The temperature at which the weight of the cured 2P resin material started to decrease was defined as the heating weight loss start temperature.

〔Effect of the invention〕

As explained above, according to the optical recording medium substrate and the manufacturing method thereof of the present invention, a highly reliable optical recording medium substrate free of optical defects can be obtained.

[Brief explanation of the drawing]

1 to 4 are schematic cross-sectional views showing the manufacturing process of an optical recording medium substrate according to the present invention.

Claims (3)

[Claims] (1) A glass substrate, a coupling agent made of ethene-based unsaturated silane applied to the surface of the substrate, and a guide groove and/or signal pit provided on the substrate via the coupling agent. A substrate for optical recording media consisting of a curable resin layer. (2) As the curable resin, (A) 10 to 50% by weight of polyurethane acrylate or polycarbonate acrylate, (B) 10 to 80% by weight of acrylic having the following structure, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Containing an acid ester and (C) 1.0 to 4.0% by weight of a photopolymerization initiator, 2
2. The substrate for an optical recording medium according to claim 1, which uses a substrate having 1 acryloyl group or methacryloyl group. (3) First, the surface of the glass substrate is cleaned with UV/O_3 and /
Alternatively, a method of manufacturing a substrate for an optical recording medium includes performing plasma cleaning, then coating the surface with ethene-based unsaturated silane, and forming a curable resin layer having guide grooves and/or signal pits on the silane film.