JPS6150232A - Optical recording medium and its manufacture - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium such as an excellent optical disc on which no exfoliation is caused even if it is left for a long time under a high moisture environment while the bonding process is executed efficiently in a short time by adhering a plastic film on the entire one side of which an adhesives is applied onto a transparent base formed with an optical recording film. CONSTITUTION:The plastic film 7 coated with the adhesives 8 on its entire face is adhered onto the transparent base 5 formed with the optical recording film 6. The thickness of the plastic film 7 is decided by the performance of work and the thickness of <=0.5mm. is handled easily. In using a plastics as the transparent base 5, the thermal expansion coefficient of the plastic film 7 due to temperature and moisture is preferably 80-120% of that of the base 5. It is preferred that the adhering is executed by means of a rubber roller or under a reduced pressure in order to prevent air bubbles from being produced between the recording film 6 and the adhesives 8 at adhering.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical recording medium and a method for manufacturing the same, particularly to adhesion of a laser recording disk.0Conventional FF1L structure and its problems Laser recording disk (hereinafter referred to as (referred to as optical disc)
is a large-capacity memory medium that can store more than 10,000 A4 documents on a disk with a diameter of less than 3 ocIn.
One bit corresponds to a small pit with a length of only about 1 μm. In addition, writing and reading information is performed by focusing a laser beam narrowed to a diameter of around 1 μm onto a disk that rotates at a high speed of over 1000 revolutions per minute, while detecting the position and adjusting the focus. Even the slightest glue on the board, deviation in parallelism, scratches, foreign objects, etc. can lead to signal errors. For this reason, the production of optical discs requires as much care in assembly as the production of semiconductors.

Conventionally, for the purpose of improving reliability of optical discs, a laser recording thin film 3 is attached to two transparent substrates 1, as shown in FIG.
．． The structure is sandwiched between the two. (However, Fig. 1 is a perspective view of an optical disc cut away, and below, part A of the cross section will be enlarged to explain the stacked state. Fig. 2 shows an example of a single-sided moonlight disc.) For,
The bonding process of bonding these two transparent substrates 1 and 2 together via the adhesive layer 4 is important, and this process often affects the yield and the reliability of the optical disk. A method using a melt adhesive is known, but this method is prone to warping and distortion of the substrate due to the simultaneous application of heat and pressure, as well as scratches and bubbles. ,
It also had many problems, including deterioration due to heat effects, and in addition, peeling IE caused by a decrease in adhesive strength under high humidity.

Purpose of the Invention The present invention solves the above-mentioned drawbacks of the conventional bonding method, and makes it possible to perform the bonding process of optical recording media such as optical disks that require high performance in a short time and efficiently. Moreover, since high temperatures are not required, there is no effect on the recording film, and furthermore, excellent optical recording media such as optical disks that provide strong adhesive strength and do not peel off even when left in high humidity for long periods of time, and their The purpose is to provide a manufacturing method.

Structure of the Invention The optical recording medium of the present invention and its manufacturing method combine a transparent disc-like substrate on which a recording thin film capable of optical recording by laser is formed and an organic film with an adhesive layer formed on one side. and an adhesive layer are bonded together so that they are in contact with each other.

Description of examples The content of the present invention will be explained using figures.

As shown in FIG. 3, the cross-sectional structure of the present invention is such that a plastic film 7 coated with an adhesive 8 over the entire surface is pasted onto a transparent substrate 5 on which an optical arrangement film 6 is formed.

The thickness of the plastic film 7 is determined by workability, and a thickness of 0.5 mm or less is easy to handle. In the case of plastic substrates, unlike glass substrates, the amount of deformation due to temperature and humidity is large, and since they are not as hard as glass, when bonding materials with different expansion coefficients depending on temperature and humidity, The warping and swells become larger. Therefore, when plastic is used as the transparent substrate 5, the expansion coefficient of the glass film 7 depending on temperature and humidity is preferably 80% to 120% of the value of the substrate 5. If a plastic film exceeding this range is used, the bonded disks will have significant warpage and waviness. If air bubbles occur between the recording film 6 and the adhesive 8 during bonding,
This may cause peeling or deterioration of the recording film 6 under high temperature and high humidity conditions. Therefore, a bonding method is required to prevent the formation of air bubbles. In the conventional method of bonding thick and inflexible substrates together, it is quite natural to prevent the inclusion of air bubbles, but the method of the present invention By using a plastic film on one side, the inclusion of air bubbles can be easily prevented.

One method is to use a roller as shown in FIG. 4, in which a plastic film 9 provided with an adhesive layer is pasted onto a disk 10 placed on a movable table 12 from one end of the disk. .

At this time, if the temperature of the roller 11 is controlled, it becomes possible to use an adhesive that requires heat and pressure bonding.

The film may be cut out in advance into the shape of the disk 1o, or the excess film may be cut off after pasting. Still another method is the reduced pressure bonding method shown in FIG. The pump 20 is used for evacuation. The film 13 coated with adhesive is pasted under reduced pressure onto the disk 14 placed on the lower stand 16. At this time, the upper and lower stands 17.
By controlling the temperature of 18, even adhesives that require heat and pressure bonding can be used.

Figure 5 shows the case where a continuous film is used.
In this case, all you have to do is cut off the excess film after pasting. Alternatively, the film may be placed on the lower stand 16 with a disk attached to one side of the upper stand, or a film cut out in advance into the shape of a disk may be used. The adhesive used here is not particularly limited in type; hot melt adhesive,
High-performance adhesive, fast-curing epoxy 7 resin, urethane resin,
You can choose from fast-curing acrylic adhesives, unsaturated polyester resins, etc. The temperature that can be heated is the recording film,
Since it changes depending on the material of the transparent substrate, the adhesive and bonding conditions should be changed accordingly, and curing using ultraviolet light is also effective.

The present invention will be explained in detail below using specific examples.

(Example 1) Table 1 shows the film, substrate, adhesive, and bonding conditions of each example in which the roll-type bonding shown in FIG. 4 was performed.

For these examples, the amount of warpage ΔD as shown in FIG.
Measured both after leaving it for 0 days and immediately after taking it out,
Table 3 shows data showing the difference.

However, the warpage toward the recording film side of the substrate is defined as +, and the warpage in the opposite direction is defined as -. At the same time, the appearance was also investigated and the results are shown in Table 3.

(Execution 112) Using the reduced pressure bonding apparatus shown in Fig. 6, 1 torr
The pressure was reduced to 100% and the parts were bonded together. Table 2 lists specific examples. The initial value of the amount of warpage ΔD described above, 4o'c-90%R
Table 3 shows the results of measuring the values after 20 days of leaving H and observing the changes. At the same time, Table 3 shows the observation results regarding the appearance.

(Comparative example) Using a commercially available hot melt applicator, a commercially available urethane hot melt adhesive Q 110'C was applied to each n of two 1.5B thick acrylic substrates, and a 30 μm thick adhesive was applied. The coated surfaces were heated and pressed together at a pressure of 5 Kp/cA for 1 minute using a hot press at 100°C. Initial value of substrate glue amount ΔD and 40'C-9
Table 3 shows the values and changes in appearance after 20 days under 0% RH.

As shown in Effect Table 3 of the invention below, all of the embodiments of the invention have a warp amount J
Even after 20 days of D75E initial storage at 40°C and 90% RH, it is as small as ±100 μm or less, and the amount of change under humidity is also small. In addition, both exhibit excellent performance in that neither bubbles nor peeling occur both initially and after the wet air acceleration test. Comparative examples in which the sheets were laminated in a conventional manner using a conventional hot-melt adhesive had a large amount of initial warp compared to these examples, and also had a very large change in humidity.

Moreover, Table 3 clearly shows that the hot melt adhesive is likely to peel off because it is difficult to avoid the inclusion of air bubbles and the plastic substrate cannot be heated at all. In other words, the optical disk adhesion method of the present invention has the characteristics that it is possible to manufacture highly reliable optical disks with high productivity, such as without the generation of bubbles or peeling defects, and with less possibility of warping of large substrates. .

[Brief explanation of drawings]

Fig. 1 is a perspective view of the optical disc cut from the center, Fig. 2 is an enlarged view of cross section A in Fig. 1, Fig. 3 is an enlarged view of the cross section of the optical disc, and Fig. 4 shows the pressure bonding process using a roller. The figure shown in FIG. 5 is a diagram illustrating a reduced pressure bonding apparatus. 1.2.5...Transparent substrate, 3,6...
Light arrangement thin film, completed...Plastic film, 4
, 8...Adhesive layer, 9.13...Adhesive plastic film, 10.14...Disc substrate, 11...Roller, 12... Moving table, 15...-upper pedestal, 16... lower pedestal,
17.18... Vertical movable axis, 19...
Vacuum chamber, 2o...exhaust system.

Claims (5)

[Claims] (1) An optical recording medium in which a plastic film coated with adhesive on one side is pasted onto a transparent substrate on which an optical recording film is formed. (2) The light according to claim 1, wherein the transparent substrate is a plastic substrate, and the expansion coefficient due to heat and humidity of the plastic film to which the adhesive is applied is 80% to 120% of the expansion coefficient of the transparent substrate. recoding media. (3) A transparent disc-shaped substrate on which a recording thin film capable of optical recording by laser is formed and an organic film with an adhesive layer formed on one side are arranged so that the laser recording thin film and the adhesive layer face each other. A method for manufacturing optical recording media that is bonded together. (4) The method for producing an optical recording medium according to claim 3, which comprises the step of bonding the disk-shaped substrate and the organic film on which the adhesive layer is formed by passing the substrate between rubber rollers. (5) The method for producing an optical recording medium according to claim 3, which comprises the step of bonding the disc-shaped substrate and the organic film on which the adhesive layer is formed by bonding them together under reduced pressure.