JPS6376128A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical information recording medium which is substantially free from uneven thicknesses and distortions and has good preservability with high mass productivity by providing recesses for deaeration at >=1 points to the outside circumferential part on the adhesive surface side of at least one of substrates. CONSTITUTION:The substrate 1 having the recesses 2 is used in the outside circumferential part on the adhesive surface side. The shape of the recesses 2 is not particularly limited and is preferably provided in the outside circumferential part of the substrate 1 within the range where said recesses does not arrive at the optical recording layer to be installed on the substrate 1. Such recesses 2 may be provided at >=1 points on the substrate as needed but they are preferably provided at the positions symmetrical with the center of the substrate 1 in the case of providing plural recesses. Such substrate 1 and an ordinary substrate 3 having no recesses are adhered by an adhesive agent 5 contg. beads in such a manner that the recording layers 4 provided to the respective substrates are positioned inside. The particular need for operations such as pressurization at the time of curing the adhesive agent is thereby eliminated and the optical information recording medium which is distortion-free and has a good life is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording medium that records and reproduces information using a light beam, and particularly relates to an optical information recording medium that is free from distortion and has good storage stability. .

[Prior Art] Conventionally, at least one of two substrates made of, for example, glass, acrylic resin, polycarbonate resin, etc. has been coated with an optical film using magneto-optic effect, photochromism, phase transition from amorphous to crystalline, etc. An optical information recording medium is known in which a recording layer is formed and a substrate is bonded with the recording layer on the inside. Conventionally, as a manufacturing method of this type of optical information recording medium, for example, Japanese Patent Application Laid-Open No. 59-186150
No. 60-226046, No. 60-229
As disclosed in Japanese Patent Application No. 256 and the like, a common method is to sandwich a spacer or glass beads between the substrates and bond the substrates to a hollow structure.

By the way, in these conventional methods, the adhesive is usually applied to one or both of the substrates and then pressure bonded, and then the adhesive is cured by heat curing, two-component curing, or ultraviolet curing to bond the substrates. However, at this time, air is forced into the space between the substrates in a compressed state, and this compressed air sometimes causes the substrates to shift in position or become uneven in thickness. To prevent this, it is necessary to apply pressure to maintain the shape of the substrate until the adhesive is sufficiently cured, which increases costs and reduces mass productivity. In addition, the optical information recording medium obtained in this way may have substrate distortion over time due to the compressed air trapped inside, and such substrate distortion may cause rotational unevenness during recording and playback. This caused deterioration of the dynamic characteristics of the lens and difficulty in adjusting the focus.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and eliminates the drawbacks of the conventional optical information recording media described above, and eliminates the need for operations such as pressurization when curing the adhesive. It is an object of the present invention to provide an optical information recording medium that does not require any distortion and has good storage stability.

[Means for Solving the Problems] The above objects of the present invention are achieved by the present invention below.

In an optical information recording medium formed by adhering two substrates having an optical recording layer on at least one of the substrates with the recording layer facing inside, at least one of the optical recording substrates is on the adhesive side. An optical information recording medium characterized by having one or more recesses for degassing on its outer periphery.

[Function] In the present invention, at least one of the two substrates to be bonded is provided with a recess for degassing on the outer periphery of the bonding surface. Air is not sucked in between the substrates as in the case of media. Therefore, it is possible to eliminate the positional deviation and thickness unevenness of the substrates caused by such air being sucked in, and furthermore, the substrates are not distorted due to the air sucked in between the substrates. Therefore, it is possible to provide an optical information recording medium with good storage stability without deterioration of dynamic characteristics during recording or difficulty in adjusting focus due to such distortion. Furthermore, since there is no air trapped, there is no need for special operations such as applying pressure when the adhesive is cured, and mass productivity can be improved. Such effects are particularly remarkable when a substrate is bonded to a hollow structure, but it goes without saying that similar effects can be obtained even when the structure is not hollow.

The present invention will be further described below with reference to the drawings. 1st
The figure is a perspective view of an example of a substrate suitable for embodying the present invention.

As shown in FIG. 1, in the present invention, a substrate 1 having a recess 2 on the outer periphery on the adhesive surface side is used.

Although the shape of the recess 2 is not particularly limited, the recess 2 is a substrate! It is desirable to provide it on the outer periphery of the substrate 1 in a range that does not reach the optical recording layer provided above. One or more such recesses can be provided on the substrate as necessary, but considering the dynamic characteristics during recording and reproduction, if multiple recesses are provided, the substrate may be It is preferable to provide the recess 2 at a position symmetrical with respect to the center of the recess 2 . This is because by doing so, it is possible to improve the rotational characteristics of the obtained optical information recording medium during recording and reproduction.

The substrate 1 is not limited to the above-mentioned disk shape, but can be of various shapes, and its materials include, for example, soda glass, quartz, Pyrex glass, polyester, acrylic resin, polymethacrylic acid ester, polyolefin resin, and phenol. Any pure material used in optical information recording media, such as resin, epoxy resin, polyamide, polyimide, or metals, can be used.

Examples of methods for forming such recesses on the substrate include mechanical cutting, or integral molding with the substrate by injection molding using a mold in which protrusions corresponding to the recesses are provided in advance.

As with conventional methods, substrates can be bonded using various adhesives such as thermosetting, two-component curing, and ultraviolet curable adhesives, but the amount of adhesive applied to the parts to be bonded such as the substrate or spacer After the air between the substrates is sufficiently degassed through the recess, the recess may be sealed with an adhesive. Of course, the recess may be sealed by injecting the adhesive after degassing instead of applying the adhesive to the recess.

Next, FIG. 3 shows an example of the optical information recording medium of the present invention produced using the above substrate. This recording medium includes a substrate 1 having a recess 2 as described above, and a normal substrate 3 having no recess, so that the recording layer 4 provided on each substrate is on the inside to contain beads. It is formed by bonding with adhesive 5.

[Examples] In order to explain the present invention more specifically, Examples of the present invention are shown below. Of course, it goes without saying that the present invention is not limited to the following 74 examples.

Example 1 Recording layer provided, thickness 1.2 mm, outer diameter 200 mm,
A disk-shaped transparent polycarbonate substrate with an inner diameter of 35 mm was prepared, and a two-component room temperature curing silicone adhesive containing 10% by weight of glass beads with a particle size of 0.5 to 0.59 mm was applied to the substrate using a dispenser. The adhesive should be applied to the outer and inner peripheries of this board, each with a width of approximately 2 m.
1 liter was applied to a height of about 1 mm.

Then, on this substrate, a substrate made of the same material as above and having a recording layer with a concave portion as shown in FIG.
The pressure was released and it was left at room temperature.

After about 6 hours, the adhesive has completely cured and the distance between the substrates is about 0.
A high quality optical information recording medium with a thickness of 6 mm and a maximum thickness unevenness of 80 mm was obtained. No misalignment occurred in this recording medium, and the recesses were also sealed. Furthermore, the dynamic characteristics were also good.

Example 2 An optical information recording medium was produced in the same manner as in Example 1 except that a substrate with a concave portion having a width of 4 mm and a length of 3 mm was used. As in Example 1, the adhesive hardened after about 6 hours. was completed, and an optical information recording medium with a maximum thickness unevenness of 90 mm was obtained. No positional shift was observed in this recording medium, and the recesses were also sealed.

Comparative Example An optical information recording medium was prepared in the same manner as in Example 1 except that two substrates without recesses were used. As a result, the two substrates could not be properly bonded together to form a recording medium. Further, the thickness unevenness was at most 250 μm, and distortion occurred.

[Effects of the Invention] As explained above, according to the present invention, it has become possible to obtain an optical information recording medium with good storage stability and almost no thickness unevenness or distortion with good mass production.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an example of a substrate used in the optical information recording medium of the present invention, FIG. 2 is a perspective view of another example of a substrate used in the optical information recording medium of the present invention, and FIG. 3 is an optical FIG. 1 is a schematic cross-sectional view of an example of an information recording medium.

Claims (1)

[Claims] (1) In an optical information recording medium formed by adhering two substrates having an optical recording layer on at least one of the substrates with the recording layer facing inside, at least one of the substrates is on the adhesive side. An optical information recording medium having one or more recesses for degassing on the outer periphery of the medium.