JPS6313147A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To prevent the productive of defectives by making the pressure which is applied to a substrate by a roll press machine small at the initial period of pressing operation and increasing it gradually afterwards. CONSTITUTION:The pressure applied to the roll 5 of the roll press machine is made constant and a roll space X is set large on the insertion side of the optical recording medium 6 of the roll press machine and small on the sending side, so that the pressure applied to the substrate 1 can be set small in the initial period and strong afterwards. Namely, the roll space and the cylinder pressure applied to the roll 5 are adjusted in order that the pressure applied to the substrate 1 is within the range of 0.5-4kg/cm<2> in the initial period of the press and the pressure applied afterwards is regulated not to exceed 7kg/cm<2>, for example, the pressure applied to the substrate 1 is made strong gradually to process the substrate 1.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing an optical recording medium.

More specifically, the present invention relates to a method of manufacturing an optical recording medium, which is formed by bonding two substrates having an optical recording layer on at least one of the substrates under pressure using a roll press machine.

[Conventional technology]

Conventionally, two recording media in which an optical recording layer utilizing magneto-optic effect, photochromism, phase transition from amorphous to crystalline, etc. is formed on a substrate such as glass, acrylic resin, or polycarbonate resin are used. Optical recording media are known that have a so-called air sandwich structure, such as a bonded structure in which two objects are bonded to face each other and a hollow structure in which two objects are bonded to each other with a spacer in between.

When bonding these recording media, adhesive is applied to the bonded portion of the recording medium or spacer, and the two media are aligned in a bonded structure, or the two media and the spacer are aligned in a hollow structure. However, they were bonded under pressure using a press machine such as a roll press machine or a pliers press machine. Comparing these two press methods, the roll press machine is advantageous in terms of mass production because it is easy to incorporate into the line.

However, this roll press machine has a problem in that the two media tend to be misaligned during pressing. below,
This problem will be explained in detail with reference to FIG.

When creating an optical recording medium with the above-mentioned bonded structure using a roll press machine, it is generally necessary to apply an adhesive to one or both of the two recording media so that the two media do not shift. Then, sufficient adhesive strength is obtained by temporarily fixing by applying a weak force from the outside, and then permanently fixing by applying it to a roll press machine having a plurality of rolls 5 as shown in FIG. 3, for example. -ing This temporary fixing is done in order to reduce misalignment when the final fixing is performed. In this state, the adhesive has not hardened or hardened, and if a strong external force is applied, it will not be possible to align the adhesive. The two media are in a state where they are misaligned, but even if such temporary fixing is performed, misalignment often occurs during actual fixing. In FIG. 3, the reference numeral 5 indicates a roll, and 6 indicates an optical recording medium. In this example, a substrate 1 and two sheets having a recording layer 2 on the substrate 1 are used. An optical recording medium 6 in which recording media are bonded with an adhesive layer 3 in between is illustrated.

Here, to briefly explain the roll press machine, a roll press machine is generally equipped with a plurality of rolls 5 having a surface layer of silicone rubber or the like on the surface, and a work piece (in this example, an adhesive It is possible to feed the optical recording medium 6) to be formed and pressurize the fed workpiece. For this reason, it is common to arrange a plurality of rolls 5 facing each other as shown in the figure, and the roll interval X is made slightly narrower than the thickness of the work to be flowed between the rolls. The workpiece is clamped so that the layers are slightly crushed, and the workpieces are sequentially fed between the rolls. The pressure applied to the workpiece can be adjusted by adjusting the pressure applied to the workpiece, such as the shilling pressure applied to the rolls, and the distance between the rolls.

By the way, when a temporarily fixed medium as described above is fed into such a roll press machine, the above-mentioned positional deviation occurs mainly due to the force in the shear direction applied to the adhesive layer. When this occurs in an optical recording medium, for example, in the case of a disk medium such as an optical disk, the center hole of the disk medium cannot fit into the center pin of the driver of the recording device that uses it, or when the disk is rotated. This may cause problems such as loss of balance. Even if such misalignment is small, it will cause a decline in dynamic characteristics during recording or playback, such as the rotational failure of the disk mentioned above, and if this misalignment is severe, it will result in a defective product. This was causing a decrease in yield.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to press the optical recording medium as described above while maintaining the feature of the roll press machine being excellent in mass productivity. To improve yield by eliminating positional misalignment at the point in time, preventing deterioration of dynamic characteristics of an optical recording medium and generation of defective products due to the positional misalignment, and ultimately producing optical recording media with excellent characteristics at low cost. An object of the present invention is to provide a method for manufacturing an optical recording medium that can be used.

[Means for solving problems]

The above objects of the present invention are achieved by the present invention as follows.

Two substrates having an optical recording layer on at least one substrate are bonded together using an adhesive or an adhesive and a spacer under pressure using a roll press machine so that the optical recording layer is on the inside. A method for manufacturing an optical recording medium, characterized in that when manufacturing an optical recording medium with a laminated structure, the press pressure applied to the substrate by the roll press is small at the initial stage of pressing, and then increased.

[Effect]

In the method of the present invention, when bonding an optical recording medium with a bonded structure using a roll press machine, the pressure applied to the substrate by the roll press machine is small at the initial stage of pressing, and then increases to form the bond. , it is possible to almost eliminate positional displacement of the substrate during pressing, especially at the initial stage of pressing when the adhesive is not sufficiently cured or solidified.

Since a large press pressure is applied after the adhesive has gradually hardened or solidified, it is possible to provide a high-quality optical recording medium that has sufficient adhesive strength and is free from misalignment.

Hereinafter, the present invention will be described in detail with reference to the drawings as necessary.

First, FIG. 1 shows an embodiment of the method of the present invention. In this example, the pressure applied to the roll 5 of a roll press machine (in the figure, the pressure is expressed as cylinder pressure).

By keeping the pressure constant (a pressure of 4 kg/cm" is illustrated) and making the roll spacing X larger on the insertion side of the optical recording medium 6 of the roll press machine and smaller on the delivery side of the roll press machine (
In the figure, as an example of the roll interval X, 2.4m is shown.
(This example shows a case where the interval is narrowed stepwise from 3 mists to 2.2 cm), in which the press pressure applied to the substrate 1 is initially small and then becomes large.

Next, FIG. 2 shows another embodiment of the present invention.

In this example, the roll interval X (in the figure, as an example, X is 2
．． The pressure applied to the roll 5 (in the figure, the cylinder pressure is set to 2 k
g/cm' → 3 kg/cm'' → 4 kg/Cm'') By increasing stepwise the press pressure applied to the substrate 1, the press pressure applied to the substrate 1 is initially small. , which was later enlarged.

In the above, the roll interval, the cylinder pressure applied to the rolls, etc. may be set arbitrarily depending on the material, shape, etc. of the desired optical recording medium, but preferably the press pressure applied to the substrate is 0.5 at the initial stage of pressing. ~4 kg/cr
rf range, and the press pressure applied afterwards is 7 kg.
It is advisable to adjust the roll spacing and the cylinder pressure applied to the rolls to a condition that does not exceed /cm. Although shown as an example, the press pressure may be increased continuously until the end of the press. Of course, it is also possible to reduce the press pressure at the beginning of the press, increase it during the middle stage, and then reduce the press pressure again.

In the present invention, various conventionally known substrates can be used without particular limitation, and among them, transparent substrates such as glass, acrylic, epoxy, and polycarbonate are preferably used. The shape may be any shape such as a disk, square, or circle.

Further, the optical recording layer may be made of any material, whether inorganic or organic, as long as it can be reproduced, recorded, or erased by light.

In addition, adhesives include hot melt, epoxy, urethane,
Although general adhesives such as acrylic, silicone, and rubber adhesives can be used without particular limitation, hot melt adhesives, rubber adhesives, and the like are particularly easy to use because they do not easily cause misalignment during temporary fixation.

Next, an example of an optical recording medium produced by applying the method of the present invention is shown in FIG. Two disk-shaped substrates 1 having the same structure are bonded together with an adhesive 3 interposed therebetween.

FIG. 5 shows another example of an optical recording medium produced by applying the method of the present invention. The optical recording medium of this example is suitable as an optical card, and is provided with an optical recording layer 2. A sheet-like substrate 1 is bonded to a protective substrate 4 via an adhesive 3.

Although not specifically explained above, various mechanical layers such as a protective layer, an antireflection layer, and a heat insulating layer, which are generally employed in conventional optical recording media, can be added to the optical recording medium as desired. It may be provided in addition to the recording layer.

〔Example〕

In order to explain the present invention more specifically, Examples of the present invention are shown below.

Example 1 The optical recording medium illustrated in FIG. 4 was produced as follows.

First, an optical recording layer 2 made of GdTbFeCo was formed to a thickness of 800 A by sputtering on each of two disk substrates 1 made of polycarbonate acid with an inner diameter of 35 layers, an outer diameter of 20 θ, and a thickness of 1.21 layers. did.

Next, the recording layer sides of the two substrates 1 on which the recording layers 2 were formed were coated with a rubber-based Ho-Melt adhesive 3 to a thickness of 30 mm, and after alignment, they were temporarily fixed.

Next, the temporarily fixed optical recording medium is inserted into a roll press machine as shown in FIG. An optical recording medium as illustrated in FIG. 4 was obtained by pressurizing and adhering it so that it became narrower.

Table 1 shows the results of measuring the amount of positional deviation of this optical recording medium after temporary fixing and pressing.

Comparative Example 1 An optical recording medium with the same structure as in Example 1 was prepared up to the temporary fixation, and was bonded under pressure using a conventional roll press machine with constant cylinder pressure and roll spacing as shown in FIG. and compared the positional deviation. The results are shown in Table 1.

Table 1 As is clear from Table 1, the cylinder pressure applied to each roll is kept constant, the roll spacing is initially wide and then gradually narrowed, and the press pressure applied to the substrate is initially small and then By increasing the size, it was possible to eliminate positional deviation during pressing of the optical recording medium.

Example 2 The optical recording medium illustrated in FIG. 5 was produced as follows.

An optical recording layer 2 was formed by coating a polycarbonate substrate 1 with a length of 85 mm, a width of 54 layers, and a thickness of 1.2 ms+ to a thickness of 800 mm using a spinner. After coating this substrate 1 with ethylene-vinyl acetate-based hot melt adhesive 3,
Film substrates 4 made of 0-polyethylene terephthalate were laminated, and after positioning, they were temporarily fixed.

The optical recording medium temporarily fixed in this way was inserted into a roll press machine as shown in Fig. 2, and the distance between the rolls was 11%
An optical card as shown in FIG. 5 was obtained by holding the cylinder pressure constant and applying pressure to the roll at a low level initially and then gradually increasing it.

Table 2 shows the results of measuring the amount of positional deviation of this optical card after it was temporarily fixed and pressed.

Comparative Example 2 Optical cards prepared in the same manner as in Example 2 up to temporary fixing were bonded under pressure using the same roll press as in Comparative Example 1, and the amount of positional deviation was measured. Table 2 shows the results.

Table 2 As is clear from Table 2, the distance between each roll is constant, and the pressure applied to the rolls is initially small.

By increasing the press pressure stepwise after that, by initially reducing the press pressure applied to the substrate and then increasing it thereafter, it was possible to almost eliminate positional deviation during pressing.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to eliminate the positional shift of the optical recording medium during pressing while maintaining the feature of excellent mass productivity of the roll press machine, and the optical recording medium due to the positional shift can be eliminated. Deterioration of the dynamic characteristics of the recording medium and generation of defective products are prevented, and it is now possible to provide an optical recording medium that is inexpensive and has excellent characteristics.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the vicinity of a roll of a roll press machine illustrating one embodiment of the present invention, and FIG. 2 is a schematic cross-section of the vicinity of a roll of a roll press machine illustrating another embodiment of the present invention. 3 are schematic cross-sectional views of the vicinity of the rolls of a roll press machine according to the conventional method, and FIGS. 4 and 5 are schematic cross-sectional views of optical recording media obtained by applying the method of the present invention, respectively. It is a diagram.

Claims (2)

[Claims] (1) Two substrates having an optical recording layer on at least one substrate are pressed by a roll press using an adhesive or an adhesive and a spacer so that the optical recording layer is on the inside. A method for manufacturing an optical recording medium, characterized in that when manufacturing an optical recording medium having a bonded laminated structure, the press pressure applied to the substrate by the roll press is small at the beginning of pressing and then increased. . (2) The press pressure applied to the substrate at the initial stage of the press is 0.
．． 2. The method for producing an optical recording medium according to claim 1, wherein the pressure is in the range of 5 to 4 kg/cm^2, and the press pressure applied thereafter does not exceed 7 kg/cm^2.