JPH02118930A - optical recording medium - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides an optical recording medium that can be reproduced, recorded, reproduced, and/or erased using a light beam using the 2P method (Photography method).
This invention relates to 2P resin materials used in manufacturing by polymerization.

[Conventional technology]

Conventionally, glass, acrylic resin, polycarbonate resin, etc. have been used as substrate materials for optical recording media. In order to perform high-density recording on an optical recording medium, it is necessary to form optical guide grooves on the substrate thereof, and two methods are conventionally known for this purpose. One method is to perform injection molding using a mold in which unevenness corresponding to the shape of the guide groove is carved, thereby transferring the guide groove at the same time as molding the substrate.

Another method is to first apply an ultraviolet curable resin or the like on a mold in which unevenness corresponding to the shape of the guide groove has been carved, and then place the substrate on this resin. 2. By irradiating the resin, the resin is cured and the resin is fixed to the substrate to form a guide groove made of the hardening resin.
This method is called the P method.

Although the former method is excellent in mass production, it has the disadvantage of poor transferability of the guide groove shape, and the problem is that only plastics, such as acrylic resin or polycarbonate resin, can be used as the substrate material. That is, in a recording medium using a plastic substrate, since the plastic substrate has air permeability, the recording layer is corroded by moisture, oxygen, etc., and its recording characteristics gradually deteriorate.

Therefore, if this method is adopted in which only plastic can be used as the substrate material, a problem arises in that it is not possible to manufacture a recording medium that can maintain its recording characteristics for a long period of time.

On the other hand, the latter method not only has good transferability of the guide groove shape, but also allows the use of glass instead of plastic as the substrate material. Therefore, by using a glass substrate provided with guide grooves by this method, a recording medium that can maintain high reliability for a long period of time can be manufactured.

The material for the 2P layer used here is required to have high heat resistance, high moisture resistance, and short curing time.

The 2P material is mainly composed of a photopolymerizable prepolymer (also called a base polymer or oligomer), a photopolymerizable polymer (also called a reactive diluent), and a photopolymerization initiator.

The photopolymerizable prepolymer is a polymer that can be polymerized by photochemical action and is an important component forming the skeleton of the 2P layer.

The photopolymerizable monomer acts as a diluent to lower the viscosity of the prepolymer, and when irradiated with light (mainly ultraviolet light), it also participates in polymerization.

Polyfunctional monomers are crosslinking agents between polymers.

Further, the photopolymerization initiator absorbs ultraviolet rays and the like to initiate polymerization.

Conventionally, a 2P layer having a structure as described in Japanese Unexamined Patent Publication No. 56-77905 has been used.

However, when a recording layer or a protective layer is formed on the cured resin material conventionally used for the 2P layer, wrinkles occur in the 2P layer when recording and reproducing are repeated or heat is applied. The problem was that N decreased.

Furthermore, when continuous molding is performed using the same stamper, transfer defects gradually occur, and optical recording media using substrates after the 100th shot have a problem in that the C/N partially decreases compared to the initial one. was there.

[Problems to be Solved by the Invention] The present invention is an optical recording medium in which concavo-convex BRIFO-771, signals and guide grooves are formed by the 2P method, and the CZN ratio does not deteriorate even during repeated recording, playback, and long-term storage. The purpose of this invention is to provide an optical recording medium with fewer optical recording media. In addition, the present invention is a 2P
Another object of the present invention is to provide a highly reliable optical recording medium that is free from transfer defects during molding of layers and has a chip-free substrate.

[Means for solving problems]

The optical recording medium of the present invention is an optical recording medium in which a concavo-convex preformat signal and a guide groove are formed in a 2P layer made of a cured resin material formed on a substrate, wherein the glass transition temperature of the cured resin material is (Tg) is 130°C or higher, and the elongation rate of the cured resin is in the range of 10 to 30%.

That is, in the present invention, in an optical recording medium in which a concavo-convex preformat signal and a guide groove are formed on a 2P layer made of a cured resin formed on a substrate, the glass transition temperature (Tg) of the cured resin is 130. ℃ or higher and the elongation rate of the cured resin is within the range of 10 to 30%, so that the 2P layer will not soften due to heat accumulation during recording and reproduction.
2 due to stress in the laminated film of the magnetic recording layer provided on the P layer
Since no distortion occurs in the P layer, deterioration of the C/N ratio can be suppressed even during repeated recording/reproduction and erasing and long-term storage.

Further, by setting the elongation rate to 10% or more, chipping of the 2P layer during molding into a 2P layer can be prevented, and transfer defects can be prevented.

Next, the present invention will be explained using figures.

FIG. 1 shows the configuration of an information recording medium of the present invention.

In Figure 1, 1 is a transparent substrate, 2 is a 2P layer on which preformat signals and guide grooves are formed, 3 is a first protective layer made of an insulator, and 4 is information recorded and reproduced by changing the reflectance and polarization angle of light. 5 is a second protective layer, 6 is an adhesive layer, and 7 is a protective substrate.

The 2P layer on which the preformat signals and guide grooves are formed is made of a cured resin having a glass transition temperature (Tg) of 130° C. or higher and an elongation rate in the range of 10% to 30%. The elongation rate of this cured resin is 50 μm thick.
was prepared and measured by a tensile test. However, the measurement conditions were a crosshead of 5 kg and a pulling speed of 4 mm/min.

Distance between chucks: 20 mm, Sensitivity scale: IKg
It was measured with

As materials for the 2P layer used in the present invention, (A) a photopolymerizable prepolymer, (B) a photopolymerizable monomer, and (C) a photopolymerization initiator are used. Here, as the photopolymerizable prepolymer (A), polyester acrylate, epoxy acrylate, polyurethane acrylate, polycarbonate acrylate, etc. are used, and particularly flexible polyurethane acrylate and polycarbonate acrylate are preferably used. As the photopolymerizable monomer (B), monofunctional acrylate compounds, difunctional acrylate compounds, and bifunctional acrylate compounds are used. For example, monofunctional acrylate compounds include 2-ethylhexyl acrylate, lauryl methacrylate,
Difunctional acrylate compounds such as hydroxyethyl (meth)acrylate, dicyclopentadiene ethoxy monoacrylate, hydrogenated dicyclopentadiene ethoxy monoacrylate, and isobornyl acrylate include 1,3-butanediol di(meth)acrylate, 1.
4-butanediol di(meth)acrylate, 1,6-
Trifunctional acrylate compounds such as hexanediol (meth)acrylate, thiethylene glycol di(meth)acrylate, neopentyl glycol-modified trimethylolpropane diacrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane triacrylate, etc. is used.

In the present invention, two or more compounds selected from the above-mentioned same type of acrylate compounds or different types of acrylate compounds may be mixed as (B), but a difunctional acrylate among the above-mentioned compounds used as (B) In particular, it is preferable to use neopentyl glycol-modified trimethylolpropane diacrylate in an amount of 60% or more of the total amount of (B).

As the photopolymerization initiator (C), known photopolymerization initiators can be used, but those with good storage stability are preferred; typical examples include p-tert-butyltrichloroacetophenone, 2,2'-jet Toxyacetophenone, acetophenones such as 2-hydroxy-2-methyl-l-phenylpropan-1-one, benzophenone, Michler's ketone (4,4'-bisdimethylaminobenzophenone), 2-chlorothioxanthone, 2-methylthioxanthone, -ketones such as ethylthioxanthone and 2-isopropynethioxanthone; benzoin and penzoin ethyls such as benzoin methyl ether and benzoin isobutyl ether; benzyl and benzyl methyl ketal; Amine compounds such as -n-butylamine, triethylamine, and diethylaminoethyl methacrylate are preferred.

The mixing ratio of the compounds (A), (B), and (C) above is (A): (B): (C) = 5-95/95-5:l in weight ratio.
~lO special i, -(A) : (B) : (C) ~1
The ratio is preferably 0-20:70-90:1-5.

The method for forming this 2P layer is not particularly limited, but for example, a spin code method or a bar code method may be used, and the film thickness of the 2P layer is 20 μm to 70 μm, particularly 30 μm to 50 μm.
7zm is preferred.

The ultraviolet rays irradiated to harden this 2P layer are 290
A region of nm to 390 nm, particularly 365 nm, is used.

As the transparent substrate 1, glass, acrylic resin, polycarbonate resin, polystyrene resin, polyolefin resin, etc. are used.

In addition, the first protective layer 3. The second protective layer 5 is made of SiN, Sin
,.

One or a combination of two of ZnS, SiC, etc. is used. The recording layer 4 includes TbCo, GdTbFe,
TbFeCo.

Amorphous magnetic recording materials such as GbTbFeCo, organic dyes such as cyanine dyes, anthraquinone dyes, merocyanine dyes, polymethine dyes, transition metal complexes (e.g. diamine metal complexes, dithiol metal complexes), etc. Examples include dyes or those introduced into polymers, and chalcogen compounds such as Bi, Te, or alloys thereof, but the present invention is particularly effective when using an amorphous magnetic recording material that has high stress when formed into a film. is particularly effective. The recording layer made of these materials is 2
It is formed on the P layer 2 by vapor deposition sputtering coating or the like.

〔Example〕

Hereinafter, the present invention will be explained in more detail using Examples.

Example 1 A 2P layer made of the above material and composition was formed on a glass substrate to a thickness of 40 μm using a spin cord. Then, a stand bar with a pattern of concave and convex preformat signals and guide grooves is pressed and exposed to ultraviolet light (365 nm).

A 2P layer having preformat signals and guide grooves was formed by irradiating with 233 mW.

A layer of Si3 with a thickness of 800 nm was deposited on the layer by sputtering.
N4 film was formed, and then 400 ml of amorphous Gd-Tb,
400 layers of amorphous Tb-Fe are sequentially stacked, a magnetic recording layer is formed, and a protective layer of Si is deposited on top of it to a thickness of 800 layers.
A film of 3N4 was formed. Next, a transparent glass plate was attached via an adhesive layer to create the optical recording medium of Example 1.

The cured resin having the composition used in this example had a glass transition temperature of 150° C. and an elongation rate of 10%.

However, the glass transition temperature and elongation rate were measured according to the following methods.

Glass transition temperature (Tg): Measured using a dynamic viscoelasticity measuring device at a frequency of 1 MHz and a heating rate of 1'C/min.

Elongation rate (%): Tensile test measuring device Ten5ilon
Crosshead 5Kg pulling speed 4. mm/min Distance between chucks 20 Distance between chucks 2 Example 2 Example 1 except that the above mixture was used as the material for the 2P layer
An optical recording medium was prepared in the same manner as above.

The cured resin used in Example 2 had a Tg of 145°C and an elongation rate of 15%.

Example 3 Example 1 except that the above mixture was used as the material for the 2P layer.
An optical recording medium was prepared in the same manner as described above.

The cured resin used in Example 3 had a Tg and an elongation rate of 20% at 50°C.

Example 4 Comparative Example 2 Example 1 except that the above mixture was used as the material for the 2P layer.
An optical recording medium was prepared in the same manner as above.

The cured resin used in Example 4 had a Tg of 130°C and an elongation rate of 30%.

Comparative Example 1 Example 1 except that the above mixture was used as the material for the 2P layer.
An optical recording medium was prepared in the same manner as above. The cured resin had a Tg of 100°C and an elongation rate of 40%.

Comparative Example 3 An optical recording medium was produced in the same manner as in Example 1 except that the above mixture was used as the 2P layer. The cured resin had a Tg of 120°C and an elongation rate of 18%.

An optical recording medium was prepared in the same manner as in Example 1 except that the above mixture was used as the 2P layer. The cured resin had a Tg of 135°C and an elongation rate of 35%.

Comparative example 4 Measurements were made by recording and reproducing a 3 MHz signal.

Table 1 An optical recording medium was prepared in the same manner as in Example 1 except that the above mixture was used as the 2P layer. The cured resin had a Tg of 150°C and an elongation rate of 7%.

It was created according to Examples 1 to 4 and Comparative Examples 1 to 4 above. Environmental durability test for optical recording media (temperature: 70°C, humidity: 90°C)
%), the C/N ratio after 500 hours, and the presence or absence of wrinkles in the 2P layer at this time were observed, and the first shot was molded using the same stamper. Table 1 shows the results of measurement of the C/N ratio of the optical recording medium prepared using the substrate and the substrates formed at the 100th shot and the 500th shot.

The C/N ratio was measured using a magneto-optical information recording/reproducing device. [Effects of the Invention] As explained above, the optical recording medium using the 2P material according to the present invention can reduce the occurrence of wrinkles in the 2P layer during high temperatures. Gana(,
No deterioration of C7/N ratio (and 2
When mass-producing preformat signals and guide grooves on the P layer, C due to transfer defects occurs even at the 500th shot.
/N ratio does not decrease.

That is, according to the present invention, it is possible to obtain an optical recording medium with improved long-term reliability and improved productivity.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of the present invention. 1...Transparent substrate 2...2P layer 3...
First protective layer 4... Recording layer weight... Second protective layer 6... Adhesive layer 7... Protective substrate

Claims (6)

[Claims] (1) In an optical recording medium in which a concavo-convex preformat signal and a guide groove are formed on a 2P layer made of a cured resin formed on a substrate, the glass transition temperature (Tg) of the cured resin is 130°C or higher. An optical recording medium characterized in that the elongation rate of the cured resin product is in the range of 10 to 30%. (2) The optical recording medium according to claim 1, wherein a photopolymerizable prepolymer and a photopolymerizable monomer are used as materials for the cured resin in a ratio of 5 to 95:95 to 5. (3) The optical recording medium according to claim (2), wherein the photopolymerizable prepolymer and the photopolymerizable monomer are used in a ratio of 10 to 30:70 to 90. (4) The optical recording medium according to claim 2, which contains a difunctional acrylate as the photopolymerizable monomer. (5) The optical recording medium according to claim (4), which contains 60% or more of the bifunctional acrylate. (6) The optical recording medium according to claim 5, wherein the bifunctional acrylate is neopentyl glycol-modified trimethylolpropane diacrylate.