JPH0447903B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an optical information recording carrier used as a digital audio disk, video disk, disk memory, etc. The present invention relates to an optical information recording carrier that can faithfully transfer signals engraved on a master disk or a transfer matrix such as a stamper, and that has excellent productivity.

[Technical background of the invention and its problems]

Generally, an information recording carrier for a digital audio disc or video disc is one in which optical information is engraved on the surface of the disc as a large number of minute signal pits.

In addition, information recording carriers for optical information recording/reproducing or erasable disk memories are usually
Although the optical information itself is not precisely engraved on the disk surface, it is a guide groove (pre-group) that allows the optical head to track with high precision.
is engraved on the surface of the optical disc.

Conventionally, methods for mass-producing optical information recording carriers in which these fine signal pits and guide grooves are carved are as follows.
First, a transfer master mold provided with signal pits or guide grooves is prepared, and then plastic is injection molded or compression molded using this mold as a mold.

However, the injection molding method or the compression molding method has disadvantages in that the molding machine is large and the transfer accuracy is low.

In order to improve these points, Polygram Co., Ltd. and Philips Co., Ltd. have researched a transfer method to form signal pits on a radiation-curable lacquer layer.
The contents are JP 51-140601 (Polygram), JP 53-116105 (Philips), JP 54-130902.
(Philips), JP-A-54-138406 (Philips), JP-A-55-4793 (Philips), etc.

In this method, a thin layer of liquid radiation-curable lacquer is applied to the surface of a master mold or stamper (a metal mold transferred from the master by electroforming), and a colorless and transparent lacquer layer is placed on top of this lacquer layer. The lacquer layer is cured by irradiating it with radiation while holding the lacquer layer on the plastic substrate. Next, the hardened lacquer layer on which the signal pits have been transferred and the plastic substrate integrally bonded thereto are peeled off from the transfer matrix to produce an information recording carrier.

However, in conventional information recording carriers, a relatively low molecular weight, colorless and transparent material with a viscosity of 100 CP or less and an average molecular weight of at most 500 is used as a radiation-curable lacquer. Poor adhesion. Therefore, if the information recording carrier is used for a long time, especially in a high humidity or high temperature environment, there is a problem that the radiation-cured lacquer layer gradually peels off from the interface with the support substrate. In addition, conventional radiation-curable lacquers shrink considerably during curing, making it impossible to achieve a 1:1 pit transfer from the transfer mold, resulting in insufficient transfer efficiency, and poor releasability from the transfer mold. There were problems such as poor productivity due to poor quality.

[Purpose of the invention]

The present invention has been made in view of the above points, and even after long-term use in a high-humidity, high-temperature environment, the adhesion between the radiation-cured lacquer layer on which signal pits are formed and the support substrate is maintained, resulting in a long service life. It is an object of the present invention to provide an information recording carrier which can be used for various applications, has excellent transfer efficiency of signal pits and guide grooves, and has improved productivity.

[Summary of the invention]

In order to achieve the above object, the present inventors produced optical information recording carriers by radiation polymerizing various radiation-curable lacquers between a transfer mold and a support substrate, and investigated the characteristics of the carriers. The present invention was completed based on the discovery that an optical information recording carrier obtained from a specific radiation-curable lacquer has extremely good adhesion to a support substrate, transfer efficiency, productivity, etc.

That is, the optical information recording carrier of the present invention is provided on a support substrate; a radiation-reactive monomer; and a radiation-reactive oligomer which is an acrylic acid or methacrylic acid modified product of a compound in which a liquid epoxide is bonded to both ends of a polyptadiene chain. A layer of polymerized cured material is applied; the radiation-cured layer is characterized in that optical signal pits are engraved on the surface of the layer.

The support base material used is an essential element for reinforcing and protecting the radiation-polymerized cured product layer, which has low mechanical strength.

Examples of the support substrate include polymeric materials such as acrylic, acetate, phenol, and epoxy resin, glass, ceramics such as _SiO2 , Al, Zn,
Examples include metal plates, disks, sheets, and films such as Cu.

In the present invention, the use of the reactive oligomer is an essential element for improving the adhesion to the support substrate, transfer efficiency, and releasability from the transfer mold.

This reactive oligomer is a compound of acrylic acid or methacrylic acid in which liquid epoxide is bonded to both ends of a polybutadiene chain [hereinafter, ``acrylic acid or methacrylic acid'' will be simply referred to as ``(meth)alrylic acid.'' ] It is a metamorphosed product.

An example of the basic structural formula of the reactive oligomer is as follows.

The above formula is an example of acrylic acid modification of a compound in which bisphenol A type liquid epoxide is bonded to both ends of a polybutadiene chain.

The polybutadiene preferably has a repeating number n of butadiene structural units of 5 to 70. When n is less than 5, transfer efficiency and mold releasability decrease;
This is because if n exceeds 60, the adhesion to the support substrate will be insufficient.

The liquid epoxide is not limited to the bisphenol A type epoxide as shown in the above formula,
It may also be of aliphatic type.

A compound in which a liquid epoxide is bonded to both ends of a polybutadiene chain, which is a raw material for the reactive oligomer, and in which the liquid epoxide is a bisphenol A type epoxide, includes, for example, NISSO epoxy manufactured by Nippon Soren Co., Ltd. EPB-12B (epoxy equivalent 450-600), EPB13 (epoxy equivalent 600-600)
780), EPB14 (epoxy equivalent 400-550), EPB17
(epoxy equivalent: 300 to 380), and examples of liquid epoxides that are aliphatic epoxides include EPB23 (epoxy equivalent:
750-900), EPB27 (epoxy equivalent weight 200-300), etc.

The reactive oligomers contained in the radiation-curable lacquer of the present invention are those oligomers further modified with (meth)acrylic acid to make them capable of radical polymerization.

The present inventors previously proposed radiation-curable polybutadiene as a reactive oligomer suitable for these uses, but this reactive oligomer was only soluble in nonpolar reactive monomers and lacked versatility. .

However, as in the present invention, the acrylic-modified reactive oligomer whose main skeleton is polybutadiene with liquid epoxy added thereto is soluble in almost any reactive monomer, so it can be easily prepared into a lacquer suitable for the application. Furthermore, the cured film of the lacquer containing this reactive oligomer is transparent to laser light.

These reactive oligomers have high viscosity,
It is used after being diluted with reactive monomers such as monoesters, diesters, triesters, and tetraesters of (meth)acrylic acid. Examples of reactive monomers include ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, n
-butyl (meth)acrylate, hexyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropene triacrylate, Examples include pentaerythritol triacrylate, pentaerythritol tetraacrylate, etc., and preferably mono(meth)acrylates having a hydrogen-bonding functional group in the ester chain and polyvalent (meth)acrylates having no hydrogen-bonding functional group. Use as a mixture of
By using such a mixture of reactive monomers, it is possible to improve the adhesion and releasability between the support substrate and the radiation-polymerized cured material layer, and also to make the radiation-curable lacquer odorless. . From the viewpoint of improving adhesion, mold releasability, and odorlessness, the weight mixing ratio of mono(meth)acrylate having a hydrogen-bonding functional group and polyhydric (meth)acrylate having no hydrogen-bonding functional group in this mixture is The ratio is preferably 5:95 to 60:40.

In addition, the weight mixing ratio of the reactive monomer and reactive oligomer in the radiation-curable lacquer is 30:70~
The ratio is preferably 95:5, more preferably 50:
The ratio should be 50-95:5. The content of reactive oligomers is
If it exceeds 70% by weight, the viscosity of the lacquer liquid becomes excessive, making it difficult to apply a thin layer onto the transfer mold, and also causing the problem that air bubbles tend to enter the lacquer liquid during coating. This is because if the ratio is less than 5% by weight, the transfer efficiency, the adhesion between the support substrate and the cured material layer, the mold releasability, etc. will decrease.

Next, a method for manufacturing an optical information recording carrier according to the present invention will be explained with reference to the accompanying drawings.

The figure is an explanatory diagram showing an example of the method for manufacturing an optical information recording carrier of the present invention.

To obtain the optical information recording carrier of the present invention, first, a transfer mold 2 is prepared, and the radiation-curable lacquer layer 3 is provided on the optical information recording surface of this mold 2 by, for example, a wet coating method.

Next, on this lacquer layer 3, for example, a transparent support substrate 4 is placed. At this time, when a glass plate or a SiO ₂ plate is used as the transparent support substrate 4, it is preferable to subject the surfaces thereof to a surface treatment with a silane coupling agent, a borane coupling agent, or the like.

In this manner, with the lacquer layer 3 sandwiched between the substrate 4 and the transfer mold 2, radiation 5 such as electron beams, gamma rays, X-rays, and ultraviolet rays is irradiated through the transparent substrate 4, and the lacquer layer 3 is harden. When the radiation used is ultraviolet rays, it is preferable to add several percent of a photoinitiator to the radiation-curable lacquer in advance. Such photoinitiators include:
For example, 1-phenyl-7,2-propanedione-2-(o-ethoxycarponyl)oxime, 2,
2-dimethoxy-2-phenylacetophenone,
Examples include benzoin isobutyl ether.

Finally, the cured lacquer layer 5 onto which the signal pits 1 have been transferred is released from the transfer mold 2 together with the substrate 4, to obtain the optical information recording carrier of the present invention.

[Effects of the Invention] As is clear from the above explanation, the optical information recording carrier of the present invention has excellent adhesion to the support substrate, and
The signal engraved on the transfer mold is faithfully transferred, and the radiation-effective lacquer used is odorless and releases easily from the transfer mold, resulting in high productivity. , its industrial applicability is extremely large.

[Embodiments of the invention]

Hereinafter, the optical information recording carrier of the present invention will be explained along with examples.

In addition, all "parts" described in the examples represent parts by weight.

Example: As a reactive oligomer, acrylic modified
10 parts of EPB14 [manufactured by Nippon Soren Co., Ltd.], 70 parts of triethylene glycol diacrylate, 20 parts of hydroxyethyl methacrylate, and 2 parts of 2,2-dimethoxy-2-phenylacetophenone as a photoinitiator were mixed. A radiation-curable lacquer was prepared.

This lacquer liquid was filled into the gap between the nickel stamper, which was a transfer mold, and the acrylic support substrate, and then ultraviolet rays were irradiated. After the lacquer liquid had hardened, the substrate was peeled off from the interface between the lacquer layer and the nickel stamper to produce an information recording carrier. At this time, the mold separation between the lacquer cured material layer and the nickel stamper and the signal transferability were good.

In addition, we conducted a cross-cut tape test (ASTM D-
3359-76), none of the 100 samples showed peeling.

Application Example When a metal reflective film is provided on the lacquer hardened layer of the information recording carrier of the present invention, a video disk that can be optically read by changing the reflectance can be obtained. Furthermore, by using the present invention, it is also possible to create a disk memory that can be optically written and read by not only transferring signal pits but also transferring spiral "guide grooves."

[Brief explanation of drawings]

The figure is an explanatory diagram showing an example of the method for manufacturing an optical information recording carrier of the present invention. DESCRIPTION OF SYMBOLS 1... Signal pit, 2... Transfer mold, 3... Radiation curable lacquer layer, 4... Transparent support substrate, 5... Radiation.

Claims (1)

[Claims] 1. On a support substrate: a radiation-polymerized cured product of a radiation-reactive monomer and a reactive oligomer that is an acrylic acid or methacrylic acid modified product of a compound in which liquid epoxide is bonded to both ends of a polybutadiene chain. 1. An optical information recording carrier comprising: a layer of radiation-polymerized cured material; and optical signal pits are engraved on the surface of the radiation-polymerized cured material layer. 2. Claim 1, wherein the ester chain of the reactive monomer is a mixture of a monoacrylate or monomethacrylate having a hydrogen-bonding functional group and a polyvalent acrylate or polyvalent methacrylate having no hydrogen-bonding functional group. The optical information recording carrier described in Section 1. 3. The optical information recording carrier according to claim 1, wherein the weight ratio of the reactive monomer to the reactive oligomer is 30:70 to 95:5. 4. The optical information recording carrier according to claim 1, wherein the weight ratio of the reactive monomer to the reactive oligomer is 50:50 to 95:5.