JPH05189820A - Manufacture of optical recording medium - Google Patents

Abstract

PURPOSE:To simply and easily manufacture an optical recording medium in the equal number of processes as in conventional cases without lowering the close contact property of a recording layer, a protective layer and the like with a substrate and without lowering the reliability of the optical recording medium. CONSTITUTION:The number of revolutions of a substrate when a solution is dropped in an operation to form a recording layer 16 on the substrate 10 by a spin coating operation is set to a value at which a centrifugal force by means of which the dropped solution advances only toward the outside of the substrate 10 can be obtained. As a result, the solution does not advance toward the inside of the substrate 10 (arrow FB), and a protective layer 20 or the like is formed so as to come into direct contact with the substrate 10. Thereby, an optical recording medium whose close contact property with the substrate 10 is good can be manufactured in the equal number of processes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical recording medium such as an optical disk, and more particularly to an improvement in a method for manufacturing an optical recording medium in which an organic dye is used as a recording layer for recording information.

[0002]

2. Description of the Related Art Optical recording media in which information is recorded and reproduced by irradiation with laser light are widely known, and various inorganic and organic materials have been researched and developed as substances used for the recording layer. Among them, the one using an organic dye in the recording layer has an advantage that it can be easily formed by a spin coating method, and thus research is actively conducted.

Various types of optical recording media have been proposed, but a structure in which a reflective layer and a protective layer are sequentially formed on a spin-coated recording layer is easy to handle. It is considered to be advantageous in terms of high reflectance.

On the recording layer made of such an organic dye,
As a method of manufacturing an optical recording medium having a structure in which a reflective layer and a protective layer are laminated, there is a method disclosed in Japanese Patent Application Laid-Open No. 2-183442, in which adhesion is improved and recording is performed by removing an extra recording layer. This is intended to improve the characteristics. Figure 4
An outline will be described with reference to the above. First, a recording layer 104 made of a dye is formed by coating on the main surface of a disk-shaped resin substrate 102 having a hole 100 in the center (see FIG. 3A).

Next, the inner and outer peripheral edges Δ104 of the recording layer 104.
Are removed, and the substrate 102 is exposed at these portions to form the non-recording area 106 (see FIG. 3B).
The recording layer 104 is removed by wiping before drying, dissolving with a solvent, and burning with laser light irradiation. After that, the reflective layer 108 and the protective layer 110 are sequentially stacked and formed. Since the reflective layer 108 and the protective layer 110 are both in contact with the surface of the substrate 102 in the non-recording area 106, good adhesion and reliability can be obtained. Also,
Good appearance.

[0006]

However, if the recording layer 104 is formed and then removed, there is a manufacturing disadvantage that the number of steps is increased. In particular, if it is attempted to completely remove the extra recording layer portion, it requires a great deal of trouble and is not preferable in terms of cost.

The present invention focuses on these points,
It is an object of the present invention to provide a method for producing an optical recording medium, which can be easily produced without deteriorating the adhesiveness and reliability of each part.

[0008]

According to the present invention, there is provided a step of forming a recording layer on which information is recorded on a substrate by a spin coating method, and a reflective layer for reflecting light for writing or reading information. In a method for manufacturing an optical recording medium, which includes a step of forming by laminating so as to cover a recording layer, and a step of forming by laminating a protective layer so as to cover this reflecting layer,
The number of rotations of the substrate at the time of dropping the solution when forming the recording layer is set to a value at which a centrifugal force that causes the dropped solution to advance only to the outside of the substrate is obtained.

[0009]

According to the present invention, the rotation speed of the substrate during spin coating of the recording layer is controlled to a predetermined value. Then, due to the action of the centrifugal force, the solution does not proceed to the inner peripheral side of the dropping position, but only to the outer peripheral side. A reflective layer and a protective layer are laminated on the recording layer thus formed. At this time, the protective layer and the like are formed in direct contact with the substrate. As a result, it is possible to easily obtain a recording medium having a good external appearance, while maintaining the adhesion between the substrate and the reflective layer or the protective layer, without making any difference in the process from the conventional manufacturing method.

[0010]

Embodiments of the method of manufacturing an optical recording medium according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the cross section of the optical recording medium in each step of this embodiment, and FIG. 2 shows the processing of each step as a flowchart. In these figures, a substrate as shown in FIG. 1A is used as the substrate 10. This substrate 10 has a disk-like shape having a hole 12 in the center, and around the hole 12, there are stepped portions or grooves 14 formed due to the relationship of the mold at the time of molding the substrate.

There is no particular limitation on the material of the substrate 10 as long as it is substantially transparent and flat with respect to the laser light used, but injection molding is performed in consideration of affinity with a recording layer described later and cost. Resin substrates according to are preferred. As the resin material, a polycarbonate type or an acrylic type is preferable, but an olefin type or an epoxy type may be used. Further, in consideration of the stability at the time of recording and reproducing information on the recording layer, it is preferable that a concentric or spiral guide groove is formed on the surface of the substrate 10.

The substrate 10 is rotated at a rotation speed higher than a predetermined value (steps S1 and S2 in FIG. 2), and the recording layer 16 is spin-coated in this state (step S3).
During this spin coating, the dropping position of the organic dye solution is
It is usually on the inner peripheral side of the substrate 10. In the normal spin coating method, the solution reaches the step portion 14 and it is impossible to provide a state without a recording layer in the innermost peripheral portion, but in the present invention, the substrate 10 has a predetermined height. It is rotating at the number of rotations. Therefore, due to the action of the centrifugal force, the dropping solution does not proceed to the inner peripheral side of the dropping position as shown by arrows FA and FB in FIG.

Since the viscosity of the dropping solution differs depending on the type of solvent or solute, the value of the rotation speed of the substrate 10 cannot be generally defined. However, according to the results of experiments conducted in relation to the present invention, when the dropping solution has a viscosity similar to that of the lower alcohol solvent, it is confirmed that the desired effect can be expected if the rotation speed is 150 rpm or more. Further, as a matter of course, when the viscosity of the dropping solution is high, the rotation speed of the substrate 10 is set to be large, and when the viscosity is low, it is set to be small. In the example described later, 250 rp
set to m. Also, regarding the outer peripheral side of the substrate 10,
The number of spin coat rotations is controlled by a method such as gradually decreasing after dropping, and the formation of the recording layer 16 in the outer peripheral region is limited.

The recording layer 16 formed in this way
Has a property that physical properties are changed, separated, and deformed by proper absorption of laser light.
The material to be used is not particularly limited as long as it has these properties and is soluble in a general organic solvent and can be spin-coated. However, organic dye solutions of cyanine, merocyanine, phthalocyanine, naphthalocyanine and the like are preferable from the viewpoint of solubility, amorphousness, high reflectivity, and the like. After the formation, the recording layer 16 is dried (step S4).

Next, as shown in FIG. 1C, the recording layer 1
A reflective layer 18 is formed on the substrate 6. As the reflective layer 18, any material may be used as long as it can reflect the laser light used for recording and reproducing information with high reflectance.
However, according to the experiments conducted on the present invention, gold, silver,
It is preferable that a metal such as copper, nickel, or aluminum, or a metal alloy using them is laminated and formed by a sputtering method or a vacuum evaporation method (step S5).

Next, as shown in FIG. 1D, the reflective layer 1
A protective layer 20 is formed on the surface 8. This protective layer 20 is
For example, it is formed by spin coating of an ultraviolet curable resin (step S6). From the viewpoint of productivity, it is particularly preferable to use a monofunctional or polyfunctional acrylic ultraviolet curable resin after spin coating. After spin coating,
The protective layer 20 is cured by the desired ultraviolet irradiation (step S7). After forming the protective layer 20, a desired process such as screen printing is performed. Further, on the outer peripheral side of the substrate 10, the recording layer 16 is dissolved and removed by the protective layer 20.

Next, examples of experiments conducted in connection with the present invention will be described. <First Experimental Example> First, a first experimental example in which an optical disk is obtained by using the present invention will be described. Polycarbonate resin substrate 1
First, the recording layer 16 is formed on the main surface of 0, that is, on the surface provided with the guide groove (not shown) for tracking. As the dropping solution, 1,1'-di-n-butyl-
3,3,3 ', 3'-tetramethyl-4,5,4',
A 5% -dibenzoindodicarbocyanine perchlorate (organic dye) dissolved in ethylene glycol monoethyl ether (solvent) at 6% by weight (solvent: organic dye = 1: 0.06 weight ratio) was used. Be done.

On the other hand, the substrate 10 is rotated on a spin coater (not shown) at a rotation speed of 250 rpm (during dropping) (step S2 in FIG. 2), and the organic dye solution is dropped in this state. The organic dye solution is 2 to 3 mm from the step portion 14 of the substrate 10 (radius 20 to 2 from the center of the substrate 10).
1 mm) (arrow F in FIG. 1 (B))
A). Then, after that, spin coating was performed while appropriately changing the rotation speed, and the recording layer 16 was formed to a thickness of about 100 nm (step S3 in FIG. 2). When the surface of the substrate 10 was observed after formation, the recording layer 16 was not formed on the inner peripheral side of the dropping position.

Next, after the recording layer 16 is dried (step S4 in the figure), the radius 20 of the substrate 10 is changed by the sputtering method.
The reflective layer 18 made of gold was formed to a thickness of 70 nm in the range of up to 59 mm (FIG. 1C, step S5 in FIG. 2). Next, a protective layer 20 made of an ultraviolet curable resin (for example, "SD-17" manufactured by Dainippon Ink and Chemicals, Inc.) was formed in a radius of 18 to 60 mm of the substrate 10 by a spin coating method in a thickness of 5 μm ( FIG. 1 (D), FIG. 2 step S6).
Further, the protective layer 20 was cured by irradiation with ultraviolet rays to obtain an optical disc (step S7 in FIG. 2).

The obtained optical disc has a radius of 18 to 25 m.
The film thickness was well kept constant even in the innermost peripheral portion of m, and no problem occurred in appearance even if screen printing was performed on the protective layer 20. In addition, a peeling test was performed on each layer using an adhesive tape, but the degree of adhesion to the substrate 10 was good and no peeling occurred.

<Second Experimental Example> Next, a second experimental example will be described. In this second experimental example, diacetone alcohol was used as the solvent for the organic dye,
An optical disc was obtained under the same conditions as the experimental example. Also in the optical disc of the second experimental example, similar characteristics to those of the first experimental example did not occur, and good characteristics could be obtained.

<Comparative Example> Next, a comparative example based on the conventional technique will be described with reference to FIG. In this comparative example, the substrate 10 has a rotation speed of 75 when the organic dye solution is dropped.
Set to rpm. Then, the organic dye solution similar to that of the first experimental example is dropped at the same position (see FIG. 7A and arrow FA) to form the recording layer 26 by spin coating. Incidentally, the reflection layer 28 under other conditions,
The formation of the protective layer 30 is exactly the same as in the first experimental example.

When the substrate surface of the optical disc manufactured in this manner was observed, the recording layer 26 was formed within the radius of the substrate 10 of 18 to 60 mm (see FIG. 7A, arrow FC). Then, when the protective layer 30 was formed, a portion of the recording layer 26 having a radius of 18 to 20 mm, that is, a portion of Δ in the same figure (A) was dissolved and removed by the UV curable resin monomer solution (the same figure (B)). reference).

The thickness of the protective layer 28 is 2 to 2 at that portion.
The thickness is as thin as 3 μm, and when the peeling test with the adhesive tape is performed, the innermost peripheral portion is peeled off, and each layer and the substrate 10 are removed.
No good result was obtained for the adhesion to

As described above, according to this embodiment, since the rotation speed of the substrate is set to a predetermined high value during spin coating of the recording layer, the solution is moved from the dropping position by the action of an appropriate centrifugal force. However, it does not proceed to the inner circumference side. That is, the formation of the recording layer on the predetermined inner peripheral side of the substrate is prevented only by controlling the rotation speed of the substrate to a predetermined value during spin coating of the recording layer in the same process as the conventional manufacturing method.

As a result, the adhesion of the reflective layer, the protective layer, etc. to the substrate is improved, the reduction of the film thickness on the inner peripheral side is prevented, and a highly reliable optical recording medium can be obtained. Further, since the resin forming the protective layer does not attack the recording layer (dye layer), the appearance becomes good.

<Other Embodiments> The present invention is not limited to the above embodiments, and includes, for example, the following. (1) As described above, it is more convenient to record and reproduce information when the guide groove for tracking is provided on the substrate. Also,
The substrate is made of resin, the recording layer is made of organic dye,
It is preferable to use a metal film formed by a sputtering method or a vacuum deposition method as the reflective layer and an ultraviolet curable resin film formed by spin coating as the protective layer in order to obtain the effects of the present invention well, but other materials or formations It goes without saying that the effects of the present invention can be expected even if a method is used.

(2) The above-mentioned dropping position of the organic dye solution and the forming range of each layer are also examples, and may be appropriately set if necessary. (3) In the above embodiment, the recording layer, the reflective layer, and the protective layer were formed on the substrate, but the present invention is also applicable to other structures such as an enhanced layer formed between the reflective layer and the protective layer. Is applicable.

[0029]

As described above, according to the method of manufacturing an optical recording medium of the present invention, the number of rotations of the substrate at the time of dropping the solution at the time of spin coating the recording layer is set to a predetermined value. Since the recording layer is not formed on the inner side of the dropping position by using the centrifugal force due to, it is possible to easily manufacture with the same number of steps as before without the deterioration of the adhesion and reliability of each part. The effect is that you can.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a cross section of an optical disc in a main process of one embodiment of an optical recording medium according to the present invention.

FIG. 2 is a flowchart showing the main steps of the above embodiment.

FIG. 3 is an explanatory diagram showing a cross section of an optical disc in a comparative example of the experimental example of the present invention.

FIG. 4 is an explanatory diagram showing a cross section of an optical disc in a main step of a conventional method for manufacturing an optical recording medium.

[Explanation of symbols]

10 ... Substrate, 12 ... Hole part, 14 ... Gap part, 16, 26 ...
Recording layer, 18, 28 ... Reflective layer, 20, 30 ... Protective layer, Δ
Areas of the recording layer that are invaded by the protective layer, FA ... Arrows indicating the dropping position of the organic dye solution, FB, FC ... Arrows indicating the traveling direction of the solution.

Claims (1)

[Claims] 1. A step of forming a recording layer on which information is recorded on a substrate by a spin coating method, and a reflection layer for reflecting light for writing or reading information are laminated so as to cover the recording layer. In the method of manufacturing an optical recording medium including a step of forming a recording layer and a step of forming a protective layer by laminating so as to cover the reflective layer, the substrate rotation speed at the time of dropping the solution at the time of forming the recording layer, A method for manufacturing an optical recording medium, characterized in that the dropped solution is set to a value at which a centrifugal force that advances only to the outside of the substrate is obtained.