JPH04344341A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain the medium which has the excellent adhesion of a protective layer in spite of long-term resting of the medium under high-temp. and high- humidity conditions and does not, therefore, peel at all even when the medium is subjected to a tape peeling test. CONSTITUTION:The recording layer of the outermost peripheral part of the veneer type optical recording medium which is formed by successively laminating the recording layers contg. dyes, reflection layer and protective layer on a thermoplastic resin substrate and allows DRAW (direct-read-after write) is removed by a solvent having >=3wt.% and >=0.5wt.% solubility to the dyes and the resin, respectively, and the film of the protective layer is so formed as to exceed the recording layers and the reflection layer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to a single-plate type optical recording medium having a high reflectance and having a dye recording layer capable of recording a large amount of information.

0002

2. Description of the Related Art A commercially available compact disc (hereinafter referred to as CD For example, an optical recording medium compatible with the player (hereinafter referred to as "Optical Data St") is compatible with the player.
orage 1989 Technical Dig
est Series Vol. 1 45 (1989)
, JP-A-2-132656, JP-A-2-168446, etc. In this optical recording medium, a protective coat layer is provided to protect the recording layer and the reflective layer. This protective coat layer is usually made of a hard resin called a hard coat in order to prevent the recording layer and the reflective layer from being damaged. Furthermore, the functions of the protective coat layer include preventing the recording layer and the reflective layer from peeling off, and preventing oxidative deterioration of the recording layer and the reflective layer, thereby improving durability. When forming a protective layer to prevent peeling of the recording layer and reflective layer and to improve durability, the recording film on the outer periphery is removed and the protective layer is applied beyond the recording layer and reflective layer. For example, forming a film is described in Japanese Patent Application Laid-Open No. 2-183442,
This is proposed in Japanese Patent Application Laid-Open No. 2-236833. However, if the medium is left in high temperature and high humidity conditions for a long time,
The inventors of the present invention have found that the above-mentioned proposed medium also has a problem in that the peel strength at the outer periphery decreases and peeling occurs from the outer periphery when a tape peel test is performed.

0003

[Problems to be Solved by the Invention] The present inventors have found that the outer periphery has excellent adhesion even when left under high temperature and high humidity conditions for a long time.
Therefore, various studies were conducted to develop a single-plate type optical recording medium that does not peel off from the outer periphery even when subjected to a tape peeling test, and as a result, the present invention was completed.

0004

[Means for Solving the Problems] That is, the present invention comprises a recording layer containing a dye, a reflective layer, and a protective layer, which are sequentially laminated on a transparent injection molded resin substrate having grooves. In write-once single-plate optical recording media in which the recording layer is coated over the innermost and outermost recording layers and the reflective layer, the outermost recording layer has the solubility of the dye used in the recording layer. 3
% by weight or more and the solubility of the substrate resin is 0.5% by weight or more by removing the optical recording medium. In the present invention, a groove is a guide groove in which information is recorded, and a land is a portion sandwiched between grooves.

The transparent injection molded substrate used in the present invention is preferably one that transmits light for recording and reading signals. It is desirable that the light transmittance is 85% or more and the optical anisotropy is small. Preferred examples include substrates using thermoplastic resins such as acrylic resins, polycarbonate resins, polyamide resins, vinyl chloride resins, and polyolefin resins. Among these, injection molded resin substrates made of acrylic resin, polycarbonate resin, and polyolefin resin are preferred from the viewpoint of mechanical strength of the substrate, ease of adding grooves and reproduction-only signals, and economic efficiency. is preferable, especially polycarbonate
A bonate resin substrate is most preferred. The shape of these substrates may be plate-like, film-like, circular or card-like. The surfaces of these substrates have grooves for controlling recording positions. Further, it may include pits for information etc. that are partially reproduced. Such grooves, pits, etc. are preferably provided when the substrate is manufactured by injection molding or casting.

In the optical recording medium of the present invention, a recording layer containing a dye, a reflective layer, and a protective layer are sequentially laminated on the transparent injection molded resin substrate. The dyes used in the layer include polymethine dyes, phthalocyanine dyes, naphthalocyanine dyes, naphthoquinone dyes, azulene dyes, and dithiol metal complex dyes that absorb in the oscillation wavelength range of semiconductor lasers. Examples include pigments that have These dyes may be substituted with various substituents in order to adjust their solubility in solvents, improve their recording properties, and the like. Further, these dyes can be used alone or in combination of two or more. Among these dyes, phthalocyanine dyes and naphthalocyanine dyes are preferred in consideration of dye durability. In the present invention, the recording layer containing the dye described above is usually formed by spin coating or spray coating.
The film can be formed by a coating method such as , dipping or the like.

When forming the above-mentioned dye into a film by a coating method, a solvent that does not damage the injection molded substrate, that is, a solvent that does not substantially dissolve the substrate resin, such as hexane, heptane,
Nonpolar solvents such as aliphatic and alicyclic hydrocarbons such as octane, decane, and cyclohexane, ethers such as diethyl ether, dibutyl ether, and diisopropyl ether, methyl alcohol, and ethyl alcohol. The dye may be dissolved in an alcohol-based polar solvent such as isopropyl alcohol, allyl alcohol, methyl cellosolve, etc. and applied.

In the present invention, after forming the recording film, the outermost recording film is removed using a solvent, but at this time, the solubility of the dye is 3% by weight or more, and the solubility of the substrate resin is 0.5% by weight.
It is preferable to use a solvent having at least 5% by weight. If you use a solvent in which the solubility of the dye does not exceed 3% by weight or the solubility of the substrate resin does not exceed 0.5% by weight, even if the initial adhesion is excellent, it will not work under high temperature and high humidity. If left for a long time under these conditions, the adhesion will deteriorate and the protective layer will peel off from the outermost periphery in a tape peel test, which is not preferable. The reason for this is probably that the dye in the recording layer was not completely removed. When removing the dye, if a solvent that dissolves 0.5% or more of the substrate resin is used, not only will the dye be removed, but the surface layer of the substrate will be moderately roughened by the solvent, and the unremoved dye will be removed. It is thought that adhesion between the protective layer and the substrate is improved because it mixes with the substrate resin.

In the present invention, the outermost recording layer may be removed after the recording layer is formed, or the recording layer may be removed after forming the following metal reflective layer on the recording layer. May be removed. Also, when forming the recording layer, it is best to apply the recording layer so that an uncoated area of the recording layer is formed in a circumferential shape on the outside of the groove created by the stamper holding jig that exists on the inner circumference of the substrate. preferable. Of course, a recording layer must be formed in the groove area of the substrate. In the present invention, specific examples of the solvent used to remove the recording layer include carbon tetrachloride,
Halogen solvents such as chloroform, methyl chloroform, 1,1,2-trichloroethane, tocrylene, dichloromethane, hydrocarbon solvents such as benzene, toluene, xylene, ketone solvents such as cyclohexanone, methyl ethyl ketone, methyl isobutyl keto, butyl cellosolve, ethyl Examples include alcohol solvents such as cellosolve, and ester solvents such as butyl acetate, amyl acetate, and cellosolve acetate. These solvents can be used alone or in combination of two or more. Furthermore, a solvent that does not substantially dissolve the substrate resin as described above used in forming the recording layer may be mixed and used within a range that does not impair the solubility of the dye and substrate resin specified in the present invention. You can also do it. The recording layer is removed by bringing these solvents into contact with the portion of the outermost recording layer to be removed by spin coating, spraying, dipping, or the like.

When forming a recording layer containing a dye, in addition to the dye mentioned above, resins such as nitrocellulose, ethylcellulose, acrylic resin, polystyrene resin, urethane resin, leveling agent, antifoaming agent, etc. are used. They can also be used together within a range that does not impair the effects of the present invention. The thickness of the recording layer is usually 30 to 1000 nm, preferably 50 nm.
~500 nm. The reflective layer provided on the recording layer in the present invention is usually preferably a thin metal film. In the present invention, in consideration of compatibility with ordinary CD players, it is preferable that the reflectance on the groove of the medium be 60% or more. Preferred metals include aluminum, gold, silver, copper, platinum, nickel, and alloys containing these metals as one component. The reflective layer of these metals can be formed by methods such as vapor deposition and sputtering. Further, the film thickness of these reflective layers is usually preferably about 50 to 200 nm. The reflective layer may be formed over the recording layer.

[0011] Furthermore, in order to protect these metal reflective films, a protective layer is further provided on the reflective layer. Resin is usually used as the protective film. In particular, ultraviolet curing resins are preferred from the viewpoint of productivity. The thickness of the protective layer is 1 to 15 μm
degree is preferred. Further, this protective layer is preferably formed over the recording layer and the reflective layer. In the optical recording medium of the present invention, signals are recorded and read by irradiating laser light through the substrate, and the wavelength of the laser light used is usually 640 to 8.
A semiconductor laser having an oscillation wavelength of 50 nm is preferred. When recording, the laser output on the recording film should be about 5 to 10 mW while rotating the medium, and when reading, the laser output should be about 1/10 of that of recording. . Further, in the optical recording medium of the present invention, printing or the like can be performed on the protective layer.

0012

[Examples] The present invention will be specifically explained below with reference to Examples, but the embodiments of the present invention are not limited thereto. Example 1 A spiral groove with a thickness of 1.2 mm and a diameter of 120 mm (depth 140 nm, width 0.5 μm, pitch 1
．． Pd-tetra (t-
After dropping a 3.5% by weight octane solution of a brominated dye (butylcyclohexyloxy)phthalocyanine (average 3.0 pieces/molecule), the resin substrate was heated at 1500 rpm.
It was rotated for 10 seconds at a speed of m. Further at 3000rpm 2
After rotating for 0 seconds, a 4:6 mixed solvent of toluent and octane was dropped onto the outermost periphery of the substrate while rotating the substrate to remove the recording layer at the outermost periphery. The 4:6 mixed solvent of toluene and octane dissolved at least 3% by weight of the dye and at least 0.5% by weight of the polycarbonate resin used for the substrate. Next, the resin substrate on which this recording film was formed was heated to 40°C.
The recording layer was dried in an atmosphere of 120 nm for 10 minutes, and a recording layer consisting essentially of phthalocyanine dye was formed on the resin substrate to a thickness of 120 nm.

A reflective layer with a thickness of 80 nm is provided on this recording layer.
A thin gold film of m thickness was formed by sputtering. However, at this time, the reflective layer was not formed on about 1 mm of the outermost circumference and about 1 mm outside of the groove of the stamper holder on the substrate. Furthermore, a 5 μm ultraviolet curing resin layer was formed on this reflective layer so as to extend beyond the recording layer and the reflective layer to prepare a medium. In order to evaluate the adhesion of the protective layer of the media produced in this way, initial and durability tests were carried out for 20 minutes at 80°C and 90% RH.
After being left for 00 hours, a tape peeling test was conducted, but no peeling of the protective layer occurred at all, both at the initial stage and after the durability test.

Examples 2-4, Comparative Examples 1-2 Example 1 was carried out in the same manner as in Example 1 except that the outermost recording layer was removed using the solvent shown in Table 1 below. The media was created and evaluated. The results are summarized in Table 1. In addition, Examples 2 to 4
The solvents used to remove the recording layer dissolved at least 3% by weight of the dye and at least 0.5% by weight of the polycarbonate resin. On the other hand, the solvents used to remove the recording layer in Comparative Examples 1 and 2 both dissolved the dye at least 3% by weight, but the solubility of the polycarbonate resin was substantially 0%.

[0015]

[Table 1]

[0016]

Effects of the Invention As is clear from the examples, the present invention provides a single-plate write-once optical recording device in which a recording layer containing a dye, a reflective layer, and a protective layer are sequentially laminated on a thermoplastic resin substrate. In the medium, the outermost recording layer is removed with a solvent having solubility for dye and resin of 3% by weight or more and 0.5% by weight or more, respectively, and a protective layer is formed so as to extend beyond the recording layer and reflective layer. It can be seen that by forming a film, the protective layer has excellent adhesion even if the medium is left for a long time under high temperature and high humidity conditions, and therefore does not peel off at all even when a tape peeling test is performed.

Claims (2)

[Claims] Claim 1: A recording layer containing a dye, a reflective layer, and a protective layer are sequentially laminated on a transparent injection molded resin substrate having grooves, and the protective layer is the innermost recording layer and the outermost recording layer. In a recordable single-plate optical recording medium coated beyond the reflective layer, the outermost recording layer has a solubility of the dye used in the recording layer of 3% by weight or more and a dissolution of the substrate resin. 1. An optical recording medium characterized in that the optical recording medium is produced by removing the viscosity with a solvent having a content of 0.5% by weight or more. 2. The optical recording medium according to claim 1, wherein the substrate is made of polycarbonate resin.