JPS63275051A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To improve an operability and to attain an efficiency by projecting an ultraviolet ray vertically to a substrate face and further projecting the ultra violet ray externally of the endface of the substrate. CONSTITUTION:The two disk substrates 2 having at least one on which a recording layer 1 for recording information by laser light are bonded by an ultraviolet ray cured-type bonding agent 3 by holding a spacer or no spacer so as to place internally the recording layer 1. At the time of bonding the substrates 2, ultraviolet ray light sources 4' are placed respectively at the internal and the external sides of a surface vertical to the bonding surface of the substrate at the external periphery end of the substrate 2 to project the ultraviolet ray. Thereby, the ultraviolet ray cured-type bonding agent layer disposed on the disk substrate is cured to the end part of the substrate without a space to completely seal the recording layer and the high efficiency and the operability is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing an optical recording medium, and more specifically, to a method for manufacturing an optical recording medium, and more specifically, an ultraviolet curable adhesive is used when bonding a recording medium that has a structure of bonding two substrates. The present invention relates to a method of manufacturing an optical recording medium that is mounted by using a method of manufacturing an optical recording medium.

[Conventional technology]

Rare earth-transition metal alloy thin film on a transparent substrate,
Reducing oxide thin film heat mode recording medium thin n such as chalcogen compound that utilizes phase transition from amorphous to crystalline
Optical recording media have been proposed, such as a laminated structure in which an optical memory material such as q is formed into a film and two recording media are bonded together so that the recording layers face each other, or an air sandwich structure in which the recording medium is bonded with a spacer sandwiched between the two recording media. .

Conventionally, adhesives such as a heat curing type, a two-component room temperature curing type, and an ultraviolet curing type have been used for adhering the recording medium. However, heat-curable adhesives cannot be used for media where the properties of the recording layer deteriorate due to the heat during curing. In addition, when plastic is used as the substrate material, the substrate may deform due to the relationship between the curing temperature of the adhesive and the thermal deformation temperature of the substrate material.
Cracks may occur at the crotch due to the difference in thermal expansion coefficient between the recording layer and the substrate.

Furthermore, in the case of a two-component room-temperature curing adhesive, a step of mixing the main ingredient and a curing agent is required, and the curing time is long, resulting in poor mass production.

On the other hand, UV-curable adhesives do not have the disadvantages mentioned above and have the advantage of being able to cure at room temperature in a short time, making them very advantageous in terms of workability and productivity. .

Conventionally, as shown in FIG. 2, when a disk substrate 2 provided with a recording layer 1 is bonded to another substrate using an ultraviolet curing adhesive 3, an ultraviolet light source 4 and a reflecting plate 5 are usually positioned above the substrate. Irradiation was being carried out. However, when optical recording media are manufactured in this manner, a problem has arisen in that the adhesive on the inner and outer peripheral end surfaces of the substrate, particularly on the outer peripheral end surface 6, is extremely difficult to cure. This is caused by the fact that light is not efficiently irradiated onto the outer peripheral end face. In particular, in the case of an air sandwich structure in which granular members 7 made of plastic, glass, etc. with uniform particle sizes are dispersed in an ultraviolet curable adhesive and used as a spacer as disclosed in JP-A-59-168947 as shown in FIG. For example, in a disk with a diameter of 11 hm, the particle size of the granular member 7 is 0.3 to 0.5+ according to the standardization specification.
The coating thickness of the ultraviolet curable adhesive 3 is desirably about am, and accordingly, the coating thickness of the ultraviolet curable adhesive 3 becomes thick, making it very difficult for the curing agent to cure, resulting in so-called stickiness.

In this way, insufficient curing of the ultraviolet curable adhesive 3 not only causes problems in appearance, but also reduces the stability of the recording layer 1 over time due to moisture and dust entering the adhesive surface and hollow portions through the gaps. Practical problems also occur, such as the influence of residual upper layer in the adhesive on the recording layer 1 and the like, or deformation and peeling of the substrate due to insufficient adhesive strength.

In addition, in order to completely cure the adhesive, it is necessary to extend the irradiation time with ultraviolet rays, which eliminates the short-time curing advantage of ultraviolet curable adhesives.

[Problem that the invention seeks to solve]

The present invention was made to solve the above problems, and its purpose is to cure the ultraviolet curable adhesive layer provided on the disk substrate to the edge of the substrate without any gaps, so that the recording layer is completely sealed. Moreover, it is an object of the present invention to provide a method for manufacturing an optical recording medium that is highly efficient and has good workability.

(Means for Solving the Problems) That is, the present invention provides two disk substrates, at least one of which has a recording layer for recording information using a laser beam, which is cured by ultraviolet light so that the recording layer is on the inside. In a method for manufacturing an optical recording medium that is formed by adhering with or without a spacer using a mold adhesive, when bonding the substrates, there is a This method of manufacturing an optical recording medium is characterized in that at least one ultraviolet light source is provided in each case and ultraviolet rays are irradiated. The present invention will be explained below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of a method for manufacturing an optical recording medium according to the present invention.

The optical recording medium manufactured according to the present invention is constructed by adhesively bonding a disk substrate 2 on which a recording layer 1 is formed with an ultraviolet curing adhesive 3 so as to have the cross section shown in FIG. As shown in Figure 3, a granular member 7 made of plastic or glass with uniform particle size is used as a spencer,
It can be bonded with a UV-curable adhesive dispersed therein to form an air sandwich structure, or it can be bonded with a UV-curable adhesive with a donut-shaped spacer (not shown) in between to form an air sandwich structure. It is composed of The material of the substrate 2 is not limited in any way and may be any material known in this field, such as plastics such as polycarbonate, polyester, acrylic resin, polyolefin resin, phenol resin, epoxy resin, polyamide, polyimide, glass, ceramics, or Metals etc. can be used.

This optical recording medium is manufactured by applying an adhesive 3 or an adhesive in which granular members 7 are dispersed onto one of the disk substrates by a predetermined coating method (for example, dispenser coating, printing method, etc.), and then applying the adhesive to the other substrate. It can be formed by folding the nails together and then irradiating the adhesive with ultraviolet light to harden the adhesive. At this time, it is difficult to cure the adhesive on the edge of the substrate, so in order to accelerate the curing, an ultraviolet light source 4' At least one. Light source 4: A high-pressure mercury lamp, a xenon lamp, etc. are used as the ultraviolet light source.
Although the position of ′ varies depending on the directivity of the light source, the elevation angle α of the outer peripheral edge of the substrate surface closest to the adhesive portion 6 is preferably 45° or less, more preferably 30° or less, and most preferably 0°. It is desirable that the substrate and the recording layer be located close to the adhesive portion 6 so that they are not affected by deformation, decomposition, etc. due to heat. If α is 45° or more, the irradiation efficiency becomes extremely poor, which is not desirable. It is preferable to use an infrared cut filter in combination because it can bring the object even closer. Depending on the intensity of the light source, it is desirable to have a large number of light sources 4' in order to shorten the irradiation time, but one light source 4' may also be provided. When irradiating ultraviolet rays, it is desirable to rotate the substrate around its central axis so that the top and end surfaces of the substrate receive the ultraviolet rays evenly. Of course, the substrate may be fixed and the light source may be moved, or both may be moved. In addition, if it is difficult to harden the end face of the inner peripheral bearing in addition to the outer peripheral end face, after the above curing operation, the board is further aligned by the outer periphery, and while the board is rotated, the inner peripheral end face is exposed to ultraviolet light from a small light source. It is also possible to irradiate. While the substrates are being rotated, it is desirable to hold the substrates under a constant and uniform pressure in order to maintain the accuracy of the spacing between the substrates. As the adhesive, acrylate radical polymerizable adhesives such as epoxy acrylate, urethane acrylate, and modified acrylate, and epoxy ionic polymerizable adhesives can be used. Note that the ultraviolet curable adhesive desirably has a general viscosity (about 1,500 to 100,000 cps) suitable for coating or printing and has appropriate thixotropy. When using a granular member dispersed in an adhesive as a spacer, examples of the material for the granular member include:
Glass, silica, metal oxide (MgO, A!20s)
Porous bodies, non-porous bodies, or hollow bodies of inorganic compounds such as the like, and plastics such as polystyrene, polyethylene, polypropylene, polyester, polyacrylic, nylon, and silicone resins may be mentioned. However, those that dissolve or swell in the adhesive are not preferred.

The shape of the granular member is not limited to a spherical shape, but may be a hexahedron or a tetrahedral column, but it is preferable that the granular member has a uniform size so that a constant distance can be maintained as a spacer between the substrates.

The size of the granular elements is usually substantially the same as the spacing between the substrates. That is, the distance between the substrates is generally t
It is often kept at og~1000μ, for example 40
This is because if a 0μ spherical body is used as a spacer, the thickness between the substrates can be controlled to approximately 400μ. Considering adhesive strength, the content of the granular material in the adhesive is 0.5% to 80% by weight relative to the adhesive, depending on the specific gravity of the granular material.
% is preferred.

Next, the present invention will be further explained with reference to an example of manufacturing an optical recording medium with an air sandwich structure in which a granular member whose substrate end face is difficult to harden is used as a spacer, and a comparative example thereof.

〔Example〕

Example 1 Outer diameter 130 + * + m, inner diameter 15 mm, thickness 1.2 mm
A recording layer was prepared by coating a donut-shaped, transparent polycarbonate disk substrate with a polymethine dye having an absorption peak around a wavelength of 830 μm using a spinner to a thickness of 750 μm.

On the other hand, spherical cross-linked acrylic resin beads classified into particle sizes of 440-490- were added and mixed as a spacer material to an ultraviolet curable urethane acrylate adhesive (3033 manufactured by Three Bond ■) so that the ffi amount ratio was 3%.

The adhesive in which the beads were dispersed was applied in a ring shape to the vicinity of the inner and outer peripheral edges of this substrate using a dispenser.

The applied adhesive had a width of approximately 2 mm, a height of approximately lam, and the cross-sectional shape of the applied adhesive was approximately semicircular.

This substrate, on which the recording layer described above was formed, was aligned so that the recording layer was on the inside and the center holes coincided with each other, and a load of 500 g was applied to the entire surface of the substrate using a nail.

Next, load B (500 g) was added to the board, and the board was rotated for 80 m while holding the load at a speed of 20 rpm.
Ultraviolet light of w/cm 2 was irradiated for 30 seconds from a light source approximately 25 c+a above the axis of the substrate. At this time, at the same time, four high-pressure mercury lamps were installed on the outer peripheral edge of the board at intervals of 90 degrees from just horizontal to the board surface (α = 0°) to a distance of 100 m per unit.
The adhesive was cured by irradiation with ultraviolet light of w/cra'.

The optical recording medium thus obtained has a substrate spacing of about 500
With U, there was no thickness unevenness, there was no stickiness of the adhesive on the edge of the board, and the hollow part could be completely sealed.

This process was then repeated continuously to produce 100 optical recording media according to the method of the present invention, and all of them were of substantially uniform quality with no dull edges. These optical recording media were subjected to an environmental test (storage test) for 2,000 hours at a temperature of 60° C. and a relative humidity of 90%, but none of them had the adhesive peeled off.

Comparative Example 1 An optical recording medium was produced in the same manner as in Example 1, except for the irradiation with the high-pressure mercury lamp right next to the substrate used in Example 1.

The optical recording medium thus obtained had no uneven thickness, but some stickiness was not observed in the adhesive at the edge of the substrate. Then, 100 optical recording media were successively produced in the same manner.
When an environmental test was carried out for 2,000 hours at a temperature of 60 DEG C. and relative humidity of 90%, no complete peeling was observed, but 122 pieces of adhesive were partially peeled off and floated. Further, the irradiation time required to eliminate stickiness at the edge of the substrate using the same light source was 2 minutes, which was four times longer than in Example 1.

Comparative Example 2 Instead of irradiating with a high-pressure mercury lamp right next to the substrate (α = 0) used in Example 1, four of the same light sources were installed at 90-degree intervals around the board at a position above the substrate at an elevation angle of 60 degrees, and the same irradiation was performed. An optical recording medium was produced in the same manner as in Example 1.

The optical recording medium thus obtained had no uneven thickness, but some stickiness was observed in the adhesive at the edge of the substrate. Next, 100 optical recording media were produced in a similar manner and subjected to an environmental test for 2000 hours at a temperature of 60°C and relative humidity of 90%. Although complete 21111I was not observed, a portion of the adhesive peeled off. There were 5 floating items. The irradiation time required to eliminate stickiness using the same light source was 1 minute, which was twice as long as in Example 1.

(Effects of the Invention) By the method of the present invention, that is, by irradiating ultraviolet rays from a direction perpendicular to the substrate surface and further irradiating ultraviolet rays from the outside of the edge surface of the substrate, the ultraviolet curable adhesive layer provided on the substrate can be cured in a short time. It hardens evenly to the edge of the board,
It becomes possible to manufacture high-quality optical recording media in which the recording layer is completely sealed with good workability and high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the method of the present invention, FIG. 2 is a schematic diagram showing a conventional method, and FIG. 3 is a schematic diagram showing an example of an air sandwich structure. 1---Recording layer, 2...Substrate, 3.
...UV curing adhesive. 4.4'--Light source, 5----One light reflector, 6.
. . . Outer peripheral end surface portion, 7 . . . Granular member.

Claims (1)

[Claims] 1. Two disk substrates, each of which has a recording layer on which information is recorded using a laser beam, are sandwiched by a spacer with an ultraviolet curing adhesive so that the recording layer is on the inside. Alternatively, in a method for manufacturing an optical recording medium configured by bonding without sandwiching, when bonding the substrates, at least one ultraviolet ray is applied to the inside and outside of a plane perpendicular to the bonding surface of the substrates at the outer peripheral edge of the substrates. A method for producing an optical recording medium, which comprises placing a light source and irradiating it with ultraviolet rays. 2. The method for manufacturing an optical recording medium according to claim 1, wherein the angle of elevation of the light source outside the plane perpendicular to the bonding surface of the substrate with respect to the bonding portion at the nearest outer peripheral edge thereof is 45° or less. 3. The method for manufacturing an optical recording medium according to claim 1 or 2, wherein granular members are dispersed in the ultraviolet curable adhesive.