JPH10106034A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium hardly causing stripping off of a substrate even for an impact and deformation and having excellent durability by using the substrate chamfering the outer peripheral end part of the outside surface of the substrate. SOLUTION: This optical information recording medium 1 is a sandwich type constituted so that a disk like substrate 11 provided with a recording layer 13, a reflection layer 14 and a protection layer 15 in this order and having a hole part 10a on its center is stuck to a disk like protection plate 12 having the same shape as this substrate so that respective recording layer sides become the inside through adhesive 16. Then, the outer peripheral end part of the outside surface of the substrate 11 is performed with the chamfering processes 17a, 17b of a shape cutting its corner part off. Although the chamfering process is preferred to be performed for both of two sheets of substrates as shown in figure, the process may be only for one side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to two disk-shaped substrates each having a recording layer, a reflective layer and a protective layer, or a recording layer and a reflective layer in this order, or a substrate having the same shape as the substrate. The present invention relates to a sandwich-type optical information recording medium capable of recording and reading information with a laser beam formed by laminating a disc-shaped protective plate having a recording layer side inside through an adhesive layer.

[0002]

2. Description of the Related Art A write-once optical information recording medium (CD-R) has been put to practical use, in which information can be recorded only once, but once written information cannot be erased. This write-once type optical information recording medium is used as a medium that meets the need to provide a CD on which information is recorded in a small number of units of several to several tens at a reasonable price and quickly.
The general structure of this medium is such that a recording layer made of a dye and a reflective layer made of a metal are provided in this order on a disc-shaped substrate, and a protective layer made of a resin is provided on the reflective layer by coating so as to cover the same. Structure. The surface of the substrate (the interface between the substrate and the recording layer) usually guides the scanning of the laser beam to be irradiated, and has a concave guide groove (generally, a pre-group) so that the laser beam accurately follows the irradiation target position. Is called)
Are formed. However, there is a problem that the above-described structure cannot be said to have sufficiently high durability and cannot sufficiently cope with recent demands for a high recording capacity.

In response to the above demands, a write-once DVD (digital video disc: DVD-R) has recently been developed as an optical information recording medium having a large recording capacity. This write-once optical information recording medium is expected to be extremely useful for storing a large amount of information such as medical charts, electronic libraries of museums and libraries, and official documents. As a basic structure of a DVD-R, for example, a structure shown in FIG. 17 has been proposed (“Nikkei New Media” separate volume [DVD], published in 1995).
That is, the DVD-R has a disk-shaped substrate 171a on which a guide groove (pre-group) for tracking is formed, an organic dye layer (recording layer) 173a formed on the disk-shaped substrate by spin coating, and further thereon. And a reflective layer 174a and a protective layer 175a in this order (the description of the reference numeral of the other disk is omitted), and the adhesive layer 176 is attached with the recording layer side inside. Since the writing (recording) and reading (reproduction) of information on the DVD-R can be performed from both sides of the substrate of the disc, the information alone is twice as large as that of the CD-R. It becomes possible to save. As another embodiment of the DVD-R shown in FIG. 17, in the above document, one disk is replaced with a disk-shaped protection plate, and a recording layer, a reflection layer, and a protection layer are sequentially provided only on one substrate. There is also disclosure of an optical information recording medium having a configuration.

[0004]

The present inventors have studied the performance of an optical information recording medium in which two disc-shaped substrates are bonded together with an adhesive layer as described above. According to this, it was found that peeling was likely to occur at the ends of the two substrates, and that the storage stability (durability) was not sufficient. And it discovered that the problem of peeling arises for the following reasons.
That is, as one embodiment of an optical information recording medium in which two disc-shaped substrates are bonded, for example, a structure as shown in FIG. 16 can be considered. In this optical information recording medium, a recording layer 163 and a reflective layer 164 are provided in this order, and the protective layer 1 is formed thereon so as to cover the reflective layer 164.
65 provided with a disk-shaped substrate 161 and a disk-shaped protection plate 16
2 are bonded via an adhesive layer 166. This medium is generally manufactured by the following steps. First, the recording layer 163 is formed on the disk-shaped substrate 161. Since the recording layer 163 is usually formed by applying a recording layer coating liquid using a spin coater,
As shown in the drawing, the coating is applied over substantially the entire surface of the disc-shaped resin substrate 161. Next, a reflective layer 164 made of metal is provided on the recording layer 163 by a method such as vapor deposition or sputtering so that the outer peripheral edge of the reflective layer is inside the outer peripheral edge of the recording layer. Next, after providing a protective layer 165 so as to cover the reflective layer 164 with an ultraviolet (UV) curable resin, the obtained substrate 161 and a protective plate (substrate) having the same shape as the substrate are obtained.
162 with an adhesive (adhesive layer 166) with the recording layer 163 inside. Thus, the structure shown in FIG. 16 can be obtained.

In general, in the above-mentioned sandwich type optical information recording medium, since the reflection layer is a layer made of metal, a sufficient bonding is made at the respective interfaces between the reflection layer and the recording layer and between the reflection layer and the protective layer. I cannot gain power. Therefore, the bonding strength between the two substrates is determined by the bonding at the respective interfaces between the layers in the region where the reflective layer is not interposed, that is, the outer region near the peripheral edge of the hole and the inner region near the outer peripheral edge of the substrate. Mainly held by force. This also means that, for example, when the medium is deformed by impact or bending, the strain appears as peeling at the edge of the substrate, particularly at the outer edge. Therefore, it is desirable that the structure of the end portion sandwiched between the two substrates be designed more firmly. However, according to further studies by the present inventor, as shown in FIG. 16, the protection layer is not directly in contact with the substrate at the outer peripheral end of the substrate of this type. And the recording layer itself is a layer made of a dye, so that it is not possible to obtain a sufficient adhesive force between the layers, so that peeling occurs at the interface between the substrate and the recording layer or between the recording layer and the protective layer. I found it easy. Also,
In addition to the lack of adhesive strength between the layers, the outer peripheral end of the conventional substrate has a shape that is formed at a substantially right angle in cross section, so that the impact tends to concentrate on the corner (corner). It was also found that the shape of the end portion of the substrate was a shape that easily caused peeling by impact. Further, the substrate is usually molded using a resin by using a stamper. For this reason, burrs often occur at the corners of the ends of the substrate. Burrs are removed in advance, but if these shavings adhere to the substrate surface, the substrate surface may be damaged in the pressure bonding process when two substrates are bonded, and this may easily hinder recording and reproduction by laser light. all right. Further, in the portion where the protective layer is in contact with the recording layer, the adhesive strength decreases over time,
It was also found that the film was easily peeled off and sufficient durability (storage stability) could not be obtained. Although the reason is not clear, the portion of the recording layer where the protective layer is in contact is susceptible to components in the protective layer, for example, radical components, and the end surface (side surface) of the recording layer is exposed, This is presumably because the recording layer is easily affected by oxygen and the like, so that the recording layer deteriorates over time.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical information recording medium in which a substrate is hardly peeled off even when subjected to impact or deformation, and which has good durability (storage stability).

[0007]

According to the research of the present inventors,
It has been found that the peeling of the substrate can be suppressed by using the substrate whose outer peripheral edge of the outer surface of the substrate is chamfered. This is presumably because the chamfering process disperses the impact without concentrating on the corners of the outer peripheral end. Particularly, with the use of the substrate having this characteristic shape, when providing the recording layer and the reflective layer on the substrate, these layers are not provided on the entire surface of the substrate up to the outer edge of the substrate, but are provided on the outer edge of the substrate. By providing the recording layer and the reflective layer while leaving the portion where the substrate surface is exposed, in a mode in which the protective layer (preferably both the protective layer and the adhesive layer) or the protective layer is not provided on the exposed surface, It has been found that by bonding the adhesive layers, a high adhesive force is realized at the edge of the substrate, and an optical information recording medium having high storage stability without peeling of the substrate can be obtained. It was made.

According to the present invention, there are provided two disk-shaped substrates having a hole at the center provided with a recording layer, a reflective layer and a protective layer in this order, or a recording layer, a reflective layer and a protective layer in this order. A sandwich-type optical information in which a disk-shaped substrate having a hole at the center provided and a disk-shaped protection plate having the same shape as the substrate are bonded via an adhesive layer such that the recording layer side is inside. An optical information recording medium (hereinafter, referred to as a first embodiment) is characterized in that at least one of the outer surfaces of the substrate has an outer peripheral edge chamfered.

Further, according to the present invention, a recording layer and a reflective layer are provided in this order, a hole is provided at the center, and the outer peripheral edge of the outer surface of at least one of the substrates is chamfered. A disc-shaped substrate, or a disc-shaped substrate provided with a recording layer and a reflective layer in this order, and a disc-shaped protection plate having a hole in the center and a disc-shaped protection plate having the same shape as the substrate. A sandwich-type optical information recording medium (hereinafter, referred to as a “substrate”) in which a disc-shaped substrate and a disc-shaped protective plate each having a chamfered outer peripheral end of an outer surface are bonded via an adhesive layer such that the recording layer side is inside. Second embodiment).

The optical information recording medium according to the first aspect of the present invention comprises:
The following embodiments are preferred. (1) Both the recording layer and the outer end of the reflective layer on the substrate are retreated inward to expose the outer end surface of the substrate, and the protective layer is bonded to the exposed surface. (2) By retracting both the inner ends of the recording layer and the reflective layer to the outside, the substrate surface in the region outside the periphery of the hole is exposed, and the protective layer is bonded to the exposed surface. (3) An adhesive layer is further joined to the exposed surface together with the protective layer. (4) The protective layer is a layer made of a UV curable resin. (5) The recording layer is a dye recording layer.

An optical information recording medium according to a second aspect of the present invention comprises:
The following embodiments are preferred. (6) By retracting both the outer end of the recording layer and the outer end of the reflective layer on the substrate, the outer end surface of the substrate is exposed, and the adhesive layer is bonded to the exposed surface. (7) By retracting both the inner ends of the recording layer and the reflective layer to the outside, the substrate surface in the outer region of the periphery of the hole is exposed, and the adhesive layer is bonded to the exposed surface. (8) The adhesive layer is a layer made of a UV curable resin. (9) The recording layer is a dye recording layer.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical information recording medium according to the present invention will be described with reference to the accompanying drawings. 1 to 4 are cross-sectional views schematically showing preferred examples of the optical information recording medium according to the first embodiment of the present invention. The optical information recording medium 1 shown in FIG. 1 has a disc-shaped substrate 1 having a hole 10a at the center where a recording layer 13, a reflective layer 14, and a protective layer 15 are provided in this order.
1 and a disk-shaped protective plate 12 having the same shape as the substrate (having a hole 10b at the center) and having a recording layer side facing inward via an adhesive layer 16, respectively. It is an example. The optical information recording medium 2 shown in FIG. 2 has recording layers 23a and 23b and a reflection layer 2 respectively.
4a, 24b and protective layers 25a, 25b are provided in this order, and two disc-shaped substrates 21a, 21b having holes 20a, 20b at the center are respectively provided with an adhesive layer 26 so that the recording layer side is inside. This is an example of a sandwich type laminated through the intermediary. As shown in FIGS. 1 and 2, the outer peripheral end of the outer surface of the substrate is chamfered 17 a, 17 b, 27 a, 27 with a corner cut off.
b has been done. The chamfering is preferably performed on both substrates as shown in the figure, but only one of them may be used.

FIGS. 3 and 4 show the regions (exposed surfaces) where the end surfaces of the substrate are exposed at the outer ends of the recording layer and the reflective layer provided on the substrate in the embodiments of FIGS. 1 and 2, respectively. Surfaces 18, 28 a, 28 b are provided, and an example of an embodiment in which the ends of the protective layers 15, 25 a, 25 b are joined to the exposed surfaces. In the present invention, as shown in FIG. 1 to FIG. 4, the recording layer and the reflective layer also have an inner end (external region of the periphery of the hole) of the substrate at a region where the substrate surface is exposed (exposed surface). It is preferable to provide 19, 29a, and 29b and join the ends of the protective layers 15, 25a, and 25b to the exposed surface.

The optical information recording medium according to the first aspect of the present invention comprises:
For example, it can be manufactured by the following method. The manufacturing method of the optical information recording medium according to the first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 5 schematically shows a state in which a recording layer 13 is provided by coating on a disk-shaped substrate 11 having a hole 10a in the center and having a corner portion of an outer end portion of the substrate surface cut off and chamfered 17. It is a fragmentary sectional view shown typically. The chamfered substrate is a stamper or mold (die) designed so that predetermined corners are chamfered in advance.
And can be obtained by molding. Alternatively, it can be obtained by performing mechanical processing after molding the substrate by a usual method. Usually, a substrate obtained by using the former method is advantageously used. By changing the design of the stamper or mold so as to have a predetermined shape, substrates of various shapes can be manufactured. Examples of these substrates will be described later.

The recording layer made of a dye is formed on a disc-shaped substrate by using a coating solution for forming a recording layer, usually by spin coating. By using the spin coating method, the application can be performed while controlling the application position (the inner end of the recording layer) in the outer peripheral region of the central hole portion to some extent. Therefore, a region where the recording layer is not formed can be formed outside the peripheral portion of the central hole. However, in order to sufficiently secure the area where the recording layer is not formed, it is preferable to remove a certain area at the inner end of the recording layer after coating the recording layer. The application can be performed by using a method such as a roll coating method or a dip coating method other than the spin coating method, but it is more difficult to control the application region by using these methods as compared with the spin coating method. It is.

Next, a reflective layer made of metal is formed on the recording layer. FIG. 6 is a partial cross-sectional view schematically showing a state in which a reflective layer 14 is further formed on the recording layer 13 and both the outer ends of the recording layer and the reflective layer are retracted inward. As shown in FIG. 6, for providing the recording layer 13 and the reflective layer 14 on the substrate 11 in a predetermined range, for example, the following method can be used. 1) The outer edge of the recording layer is washed away by a spin coating method (spin cleaning) using a suitable solvent to a predetermined position, and the recording layer in that area is removed. After that, a reflective layer is formed by masking. The reflection layer can be formed by using a method such as evaporation, sputtering, or ion plating. 2) After forming the reflective layer on the recording layer by masking in the same manner as described above, the recording layer at the portion protruding from the reflective layer (outer edge of the recording layer) is washed away by the spin cleaning described above.
The protruding portion of the recording layer is removed. 3) After the reflective layer is formed on the recording layer by masking in the same manner as described above, in the next step of applying a coating liquid for forming a protective layer, this coating liquid is applied by a spin coating method while simultaneously forming the outer edge. The recording layer is washed away, and the recording layer in that area is removed. By using this method, coating for forming the protective layer can be performed simultaneously with the removal of the recording layer at the outer end.

In order to remove the recording layer at the outer end, in addition to the spin cleaning as described above, a method of wiping off the recording layer after application and before drying the recording layer, or a method of burning with a laser beam can be used. . These methods can also be used in combination when a region where the recording layer is not formed is formed in the outer peripheral region of the central hole. The method of forming the recording layer in a predetermined range by removing the recording layer at the outer end portion as described above is described in, for example, JP-A No. 2-18.
No. 3442 and No. 2-236833, and these methods can be used. According to the above-described method, both the outer end portions of the recording layer 13 and the reflective layer 14 can be retracted inward, and the region (exposed surface) 18 exposed on the surface of the end portion of the substrate can be formed.
The region where the surface of the substrate edge is exposed is a region where the protective layer is directly bonded to the substrate surface, and this region extends along the outer edge of the entire circumference of the substrate in a range of 0.05 mm to 10 mm. Preferably, it is provided with a width. More preferably, this region is provided with a width in the range of 0.2 mm to 1.0 mm. The area where the substrate surface is exposed is
Although the dye is not completely removed but remains partially, even in such a case, there is almost no problem in bonding the protective layer.

Next, a protective layer is formed on the recording layer and the reflective layer. FIG. 7 is a partial cross-sectional view schematically showing a state in which the protective layer 15 is provided so that the end of the protective layer is in contact with the exposed region (exposed surface) 18 from above the recording layer 13 and the reflective layer 14. is there. As described later, the protective layer is formed by applying a resin such as a thermoplastic resin, a thermosetting resin, or a UV (ultraviolet) curable resin from the reflective layer to the exposed surface of the end surface of the substrate. Can be formed, but from the viewpoint of productivity and the strength of the obtained medium, UV
The use of (ultraviolet) curable resins is preferred. When a UV-curable resin is used, a protective layer can be formed by applying the resin liquid by using a spin coating method or the like and then irradiating UV light. As shown in the figure, it is preferable that the protective layer 15 be provided so that the inner end thereof is in contact with the area (exposed surface) 19 where the recording layer is not formed in the outer peripheral area of the central hole.

As shown in FIGS. 5 to 7, a substrate 11 provided with a recording layer 13, a reflective layer 14, and a protective layer 15 in this order is then replaced by a disk-shaped protective plate having the same shape as that of this separately prepared substrate. The substrate is superposed on the (substrate) 12 with the recording layer facing inward, and is bonded with an adhesive. For bonding two substrates,
After applying an adhesive on one or both substrates, the bonding surfaces of the substrates are overlapped, and for example, sandwiched between pressing plates 81a and 81b of a crimping device 80 shown in FIG. Can be performed. The adhesive can be used by appropriately selecting an adhesive such as a thermoplastic resin, a thermosetting resin, or a UV (ultraviolet) curable resin. However, when an optical information recording medium having a configuration as shown in FIGS. 2 and 4 is formed, it is difficult to use a UV-curable resin adhesive because a recording layer is provided on both substrates. Therefore, in the case of the type shown in FIGS. 2 and 4, an adhesive other than the UV-curable resin adhesive is used. In the case where a UV-curable resin is used, a transparent material is used for the pressure plate because UV light is irradiated while performing a pressure treatment. For example, white plate glass, quartz glass, and blue plate glass can be mentioned as preferable ones. The adhesive layer is usually formed so that its end face (side face) is substantially the same as the end face (side face) of both substrates (the same face) or slightly inside, but this side face shape is somewhat concave. There is no particular problem whether the shape is convex or convex.

The optical information recording medium according to the first aspect of the present invention comprises:
By adjusting the masking position, for example, FIG.
As shown in (a), the reflective layer 14 may have a shape in which the recording layer 13 is entirely covered. Further, as shown in FIG. 9B, the recording layer 13 can be formed into a two-layer configuration (recording layers 13A and 13B) via an intermediate layer 50. Further, FIG.
As shown in (c), the recording layer 13 has a two-layer structure (the recording layers 13A and 13B) with the intermediate layer 50 interposed therebetween, and the upper layers cover the lower layers as a whole. It can also be configured. These optical information recording media can also be manufactured by utilizing the manufacturing method described above.

Another example of the chamfered substrate used for the optical information recording medium according to the first embodiment of the present invention will be described below. FIG. 10 is a partial cross-sectional view schematically showing examples in which the outer end of the substrate surface is chamfered in various shapes. As shown in FIG. 10A, the shape of the outer end of the substrate can be a rounded shape as shown in FIG.
As shown in (b), FIG. 10 (c) and FIG. 10 (d), the shape of the end including the side surface of the substrate may be a semicircle, a triangle, or a polygon.
However, when the tip has a pointed shape as shown in FIG. 10 (c), it is preferable that the angle of the tip is made as obtuse as possible so that the impact or the like is not concentrated on the tip.

The optical information recording medium according to the first aspect of the present invention comprises:
As shown in FIG. 11, the protective layer 15 may be provided so as to be in contact with only a part of the exposed surface of the substrate, and the adhesive layer 16 may be in contact with the remaining exposed surface. The formation of the exposed surface in the area where the adhesive layer 16 comes into contact can be performed by applying the protective layer, dissolving the protective layer in the necessary area by the above-described method such as spin cleaning, and washing away from the substrate surface.

The above description of the method for manufacturing an optical information recording medium is based on the example of the sandwich type shown in FIG. 3, but the sandwich type optical information shown in FIG. 1, FIG. 2 or FIG. In the case of a recording medium, it can be similarly manufactured. Also, in these embodiments, as described above, the recording layer can be formed into a two-layer structure with an intermediate layer interposed therebetween (FIG. 9B). (See FIG. 9).
(A), FIG. 9 (c)). Further, an optical information recording medium can be manufactured by using a substrate whose outer end is chamfered in various shapes as shown in FIG.

Next, the optical information recording medium of the second embodiment will be described in detail. Examples of the optical information recording medium according to the second aspect of the present invention include those as shown in FIGS. 12 to 15 are cross-sectional views schematically showing preferred examples of the optical information recording medium of the present invention. The optical information recording medium 5 shown in FIG.
A disc-shaped substrate 31 provided with a recording layer 33 and a reflective layer 34 in this order and having a hole 30a at the center, and a disk-shaped protective plate 3 having the same shape as the substrate (having a hole 30b at the center).
2 with the adhesive layer 3 so that the recording layer side is inside.
6 is an example of a sandwich type bonded through the intermediary 6. The optical information recording medium 6 shown in FIG. 13 has two disk-shaped substrates 41a having holes 40a and 40b at the center where recording layers 43a and 43b and reflection layers 44a and 44b are provided in this order, respectively. 41b is an example of a sandwich type in which the recording layers 41b are bonded via an adhesive layer 46 such that the recording layer side is on the inside. 12 and 13
As shown in the figure, the outer peripheral edge of the substrate surface is chamfered 37a, 37b, 47 in a shape with its corners cut off.
a and 47b. Although both substrates are preferably chamfered as shown in the figure, only one substrate may be used.

FIGS. 14 and 15 correspond to FIGS.
13, the regions (exposed surfaces) 38, 48a, and 48b where the surfaces of the substrate edges are exposed are provided at the outer edges of the recording layer and the reflective layer provided on the substrate. This shows an example of an embodiment in which the end portions of the adhesive layers 36 and 46 are joined to the end portions. In the present invention, as shown in FIG. 12 to FIG. 15, a region (exposed surface) where the substrate surface is exposed also at the inner end portions (outer regions of the periphery of the hole) of the recording layer and the reflective layer. ) 39, 49a, 49b are provided,
It is preferable to bond the ends of the adhesive layers 36 and 46 to the exposed surface. 14 and 15, since the adhesive layer is directly bonded to the exposed surface of the substrate, the adhesive strength at the edge of the substrate can be increased. Therefore, a structure in which the end of the substrate is hard to peel off can be obtained.

The optical information recording medium of the second embodiment is manufactured basically in the same manner as the optical information recording medium of the first embodiment shown in FIGS. 1 to 4 except that no protective layer is provided. be able to. In the production of the optical information recording medium of the second aspect, the step of providing the protective layer can be omitted, so that there is an advantage that the production process can be simplified, and the productivity can be increased. Also in the second embodiment, the above-mentioned adhesive can be used for bonding the two substrates. In particular, FIG.
When the optical information recording medium of the embodiment shown in FIG. 14 is manufactured, ultraviolet (U)
V) Since light irradiation is possible, it is preferable to use a UV curable resin. At the time of bonding the two substrates, a region where the surface of the substrate end is exposed (exposed surface)
It is preferable to use the entire area (the area of the exposed surface over the entire circumference) to bond to the adhesive layer in order to obtain higher adhesive strength, but not all of the area is in contact with the adhesive layer. You don't have to. That is, there may be a portion where the adhesive layer is not provided on the exposed surface of the substrate.
Preferably, the adhesive layer is provided so that at least a half of the area where the end surface of the substrate is exposed contacts the adhesive layer.

In the optical information recording medium according to the second embodiment of the present invention, as described in the case of the embodiment shown in FIG.
The recording layer may have a two-layer structure with an intermediate layer interposed therebetween, or a reflective layer may be provided so as to cover the entire recording layer. Further, an optical information recording medium can be manufactured using a substrate whose outer end is chamfered in various shapes.

In producing the optical information recording medium of the present invention, materials conventionally used for optical information recording media can be selected and used. Hereinafter, these materials will be briefly described. As a disc-shaped substrate material, for example,
Acrylic resin; polyvinyl chloride, polyvinyl chloride resin such as copolymer of vinyl chloride and another polymer; epoxy resin; polycarbonate resin; amorphous polyolefin and polyester. Preferred are polycarbonates, polyolefins and cell cast polymethyl methacrylate.

An undercoat layer may be provided on the surface of the substrate on which the recording layer is provided, for the purpose of improving flatness, improving adhesiveness, improving the form of the substrate, and preventing deterioration of the recording layer. Materials for forming the undercoat layer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol,
N-methylol acrylamide, styrene / vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin,
High-molecular substances such as polyester, polyimide, vinyl acetate, vinyl chloride copolymer, ethylene, polypropylene, and polycarbonate, and inorganic oxides (SiO ₂ , Al ₂ O
₃ ) and inorganic substances such as inorganic fluorides (MgF ₂ ). The undercoat layer is formed by using a known method (a coating method such as spin coating, dip coating, or extrusion coating, or a vacuum film forming method such as evaporation, sputtering, or ion plating) using the above materials. You can also.

On the substrate (or undercoat layer), a pre-group layer and / or a pre-pit layer may be formed in order to form irregularities indicating information such as tracking grooves or address signals. As a material for forming the pregroup, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester, and tetraester and a photopolymerization initiator can be used. The pre-group layer can be formed by a conventional method.

The recording layer is preferably constituted by a layer made of a dye. The dye used is not particularly limited. For example, cyanine dyes, phthalocyanine dyes,
Imidazoquinoxaline dyes, pyrylium / thiopyrylium dyes, azulenium dyes, squalilium dyes, metal complex dyes such as Ni and Cr, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenyl Examples include methane dyes, triallylmethane dyes, merocyanine dyes, oxonol dyes, aluminum / diimmonium dyes, and nitroso compounds. Among these dyes, cyanine dyes, phthalocyanine dyes, azulhenium dyes, squalilium dyes, oxonol dyes, and imidazoquinoxaline dyes are preferred. The recording layer can be formed by dissolving the dye and, if necessary, the binder in a solvent to prepare a coating solution, applying the coating solution on a substrate by the method described above, and drying. The recording layer generally has a thickness of 10 to 550 nm.
Is provided so as to have a thickness in the range. As shown in FIGS. 9B and 9C, the intermediate layer can be formed using the material used for forming the undercoat layer. The intermediate layer is generally provided to have a thickness in the range of 1 to 100 μm.

The light-reflective substance that is the material of the reflection layer is a substance having a high reflectance with respect to laser light. Specifically, the reflection layer is preferably a layer made of a metal and a metalloid. Examples of these include Mg, Se, Y, Ti, H
f, V, Nb, Ta, Cr, Mo, W, Mn, Re, F
e, Co, Ni, Ru, Rh, Pd, Ir, Pt, C
u, Ag, Au, Zn, Cd, Al, Ga, In, S
i, Ge, Te, Pb, Po, Sn and Bi. Of these, Au, Ag, C
u, Pt, Al, Cr and Ni,
In particular, Au is preferable. These may be used alone or in combination of two or more. The reflective layer is generally provided to have a thickness in the range of 10 to 300 nm.

The material (adhesive) used for forming the protective layer or the adhesive layer may be a thermoplastic resin, a thermosetting resin, a UV (ultraviolet) curable resin, or an adhesive made of these resins. Can be mentioned. Among these, use of a UV curable resin is particularly preferred. UV
Examples of the curable resin include oligomers of (meth) acrylates such as urethane (meth) acrylate, epoxy (meth) acrylate, and polyester (meth) acrylate, and monomers such as S (meth) acrylate.
Further, an ordinary UV curable resin such as a photopolymerization initiator can be used. The protective layer is provided so as to have a thickness of generally 0.1 to 100 μm, preferably 1 to 15 μm. The adhesive layer has an average thickness of 0.1 μm
The thickness is set to be in a range of from 100 to 100 μm, preferably in a range of from 20 to 80 μm, and more preferably in a range of from 30 to 70 μm.

[0034]

EXAMPLES Examples and comparative examples of the present invention will be described below. [Example 1] A dye represented by the following structural formula

[0035]

Embedded image

Is dissolved in 2,2,3,3-tetrafluoropropanol to form a coating solution for forming a dye recording layer (dye 2.65).
% By weight). A tracking guide is provided,
Disc-shaped polycarbonate substrate (outer diameter: 120 mm, thickness: 0.6 m) with chamfered outer edge of substrate surface
m, inner diameter 15 mm, groove width: 0.4 μm, depth:
200 nm, shape of corner portion formed by chamfering (shape of cut-off portion): 0.2 mm in thickness direction,
(0.2 mm in diameter direction), the coating solution was applied by spin coating at a rotation speed of 1000 rpm. Subsequently, a certain area outside the vicinity of the hole periphery is wiped off,
The inner end of the recording layer was receded outward to form an exposed region of the substrate surface (exposed surface of the inner end). Thereafter, the coating layer is dried at a temperature of 70 ° C. for 10 minutes to have a film thickness of 12
A recording layer of 0 nm was formed (see FIG. 5). Au is vapor-deposited on the above-mentioned dye recording layer using a mask to have a thickness of 100 nm.
Was formed. By this operation, the reflective layer was provided so that the outer peripheral edge was located inside the outer peripheral edge of the recording layer. On the substrate surface provided with the reflective layer,
A solvent of 2,2,3,3-tetrafluoropropanol was sprayed by a spin coating method to remove a recording layer applied to an area other than an area where the reflective layer was provided. As a result, a region where the substrate surface was exposed (exposed surface at the outer end) was formed at the outer end of the substrate. This exposed surface was formed with a width of 0.5 mm along the outer edge of the circumference of the substrate (FIG. 6).
reference). On the reflective layer, a UV curable resin liquid (trade name:
3070 (manufactured by Three Bond Co., Ltd.) was applied at a rotation speed of 1500 rpm by a spin coating method. The coating layer was cured by irradiating ultraviolet rays from a high-pressure mercury lamp with a high-pressure mercury lamp to form a protective layer so that the layer thickness was 5 μm (FIG. 7).
reference). Next, a UV curable adhesive (trade name: 3070, manufactured by Three Bond Co., Ltd.) was applied on the protective layer at a rotation speed of 1500 rpm by a spin coating method. Then, the substrate on which the adhesive has been applied and a disc-shaped polycarbonate substrate (protective plate) (outer diameter: 120 mm, thickness: 0.6 mm) prepared separately are overlapped with the surface on which the adhesive has been applied inside. Then, it was sandwiched and set between pressure plates (quartz glass) of a crimping device shown in FIG. Then, in a pressurized state (0.2 kg / cm ² ), ultraviolet rays are irradiated from a pressure plate in contact with the protection plate with a high-pressure mercury lamp to cure the pressure plate, thereby forming an adhesive layer having a layer thickness of 8 μm. did. Thus, an optical information recording medium having the structure shown in FIG. 3 was manufactured.

Example 2 An optical information recording medium according to the present invention was manufactured in the same manner as in Example 1, except that the protective layer was not provided. Thus, FIG.
An optical information recording medium having the structure shown in FIG.

[Comparative Example 1] In Example 1, a disc-shaped polycarbonate substrate having the same shape without chamfering was used, and after forming a reflective layer, a region other than the region where the reflective layer was provided was formed. An optical information recording medium was manufactured in the same manner as in Example 1, except that the recording layer applied to the optical recording medium was not removed. Thus, an optical information recording medium having the structure shown in FIG. 16 was manufactured.

[Evaluation as Optical Information Recording Medium] The optical information recording medium obtained as described above was subjected to (1) drop test and (2) measurement of C / N at the outer end of the substrate.
evaluated. (1) Drop test Drops were dropped on a concrete floor 10 times from a height of 1 m, and peeling of the outer end of the substrate was observed. The evaluation criteria are as follows. A: Almost no peeling of the outer edge of the substrate was observed. B: Peeling of the outer edge of the substrate was slightly observed. C: Peeling of the outer edge of the substrate was considerably observed. (2) C / of the outer edge of the substrate (the outermost peripheral portion of the groove)
Measurement of N Using DDU1000 (manufactured by Pulstec), 1.2 m
After recording at 11 T / sec, the data was reproduced and measured with a spectrum analyzer TR4135 (manufactured by Advantest Corporation). After the production, 24 hours at 80 ° C. and 85% RH.
After storage for 0 hour, the state of the peeling of the medium outside edge of the medium and the C / N of the medium outside edge were measured, and evaluated by the same criteria. Table 1 shows the results.

[0040]

[Table 1] Table 1 ──────────────────────────────────── Drop test End C / N Storage External appearance after storage C / N after storage ──────────────────────────────────── Example 1 A 56 dB A 54 dB Example 2 A 56 dB A 54 dB Comparative Example 1 C 55 dB C 52 dB ──────────────────────────────── ────

From the results shown in Table 1, the outer surface of the substrate was chamfered at the outer peripheral edge, and the recording layer and the reflective layer on the substrate were retracted inward to provide an exposed surface of the substrate. The optical information recording medium according to the first aspect (Example 1) according to the present invention in which the protective layer is directly bonded to the exposed surface,
Compared with a comparative optical information recording medium (Comparative Example 1) in which a substrate formed by a normal method without chamfering is used and a protective layer is provided so as to be joined to an end of the substrate via a recording layer. It can be seen that there is almost no peeling at the edge of the substrate and a high edge C / N value can be obtained. In addition, these optical information recording media can be stored for a long time (especially, storage under high temperature and high humidity)
Also in this case, the medium according to the present invention hardly peels off at the substrate end compared with the medium of the comparative example, and also maintains a high end C / N value. In addition, a substrate whose outer peripheral edge on the outer surface of the substrate is chamfered is used, and the recording layer and the reflective layer on the substrate are retracted inward to provide an exposed surface of the substrate, and the adhesive layer is directly formed on the exposed surface. Optical information recording medium of second embodiment according to the present invention so as to be bonded (Example 2)
Also, it can be seen that, as compared with the optical information recording medium of Comparative Example 1, the end portion of the substrate hardly peels before and after storage, and a high value of the end portion C / N can be obtained.

[0042]

According to the optical information recording medium of the present invention, since the outer peripheral edge of the outer surface of the substrate is chamfered, for example, even if an impact is applied to the edge of the substrate, the impact force is reduced. Are dispersed without concentrating on the corners of. Therefore, peeling of the substrate end can be prevented. In particular, in the internal structure of the sandwich type substrate, the recording layer and the reflective layer on the substrate are receded to provide an exposed region of the substrate surface, and the protective layer or the adhesive layer is bonded to the exposed surface. As a result, high adhesiveness can be realized at the end of the substrate. Therefore, in the optical information recording medium of the present invention using a substrate having a specific shape subjected to chamfering and improving the structure of the end portion of the substrate to a stronger structure, peeling at the end portion of the substrate hardly occurs. Absent. In addition, the substrate can be formed into a shape with less burrs by chamfering, so that the operation of removing burrs can be simplified and generation of scratches on the substrate surface due to burrs can be suppressed. Furthermore, in an optical information recording medium in which the recording layer and the reflective layer on the substrate are recessed, the recording layer and the reflective layer are completely covered by the protective layer or the adhesive layer. Protective layer,
Alternatively, the area that is in contact with the adhesive layer is only the outer peripheral end face (side face) of the recording layer, and this face is also directly shielded from outside air, so that high storage stability can be ensured. Therefore, high durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a preferred example of an optical information recording medium according to a first embodiment of the present invention.

FIG. 2 is a sectional view schematically showing another preferred example of the optical information recording medium according to the first embodiment of the present invention.

FIG. 3 is a sectional view schematically showing another preferred example of the optical information recording medium according to the first embodiment of the present invention.

FIG. 4 is a sectional view schematically showing another preferred example of the optical information recording medium according to the first embodiment of the present invention.

FIG. 5 is a partial cross-sectional view schematically showing a state in which a recording layer is provided by coating on a disk-shaped substrate in which the outer peripheral edge of the outer surface of the substrate is chamfered.

FIG. 6 is a partial cross-sectional view schematically showing a state in which a reflective layer is further formed on the recording layer, and both the outer ends of the recording layer and the reflective layer are retracted inward.

FIG. 7 schematically shows a state in which a protective layer is provided from above the recording layer and the reflective layer such that the end of the protective layer is in contact with a region (exposed surface) exposing the end surface of the substrate. It is a partial sectional view.

FIG. 8 is a diagram schematically showing a state in which two substrates are sandwiched between pressure plates of a pressure bonding apparatus and pressure processing is performed.

FIG. 9A is a partial cross-sectional view schematically showing an optical information recording medium of a first embodiment having a reflective layer having a shape covering the entire recording layer. FIG. 9B is a partial cross-sectional view schematically showing the optical information recording medium of the first embodiment when the recording layer has a two-layer structure with an intermediate layer interposed. FIG. 9C schematically shows the optical information recording medium of the first embodiment in which the recording layer is formed as a reflective layer that covers the entire surface, and the recording layer has a two-layer structure with an intermediate layer interposed therebetween. It is a partial sectional view.

FIG. 10 is a partial cross-sectional view schematically showing an example in which the outer peripheral end of the outer surface of the substrate is chamfered in various shapes.

FIG. 11 is a partial cross-sectional view schematically showing a state in which an adhesive layer is provided so as to be in contact with a region where the end surface of the substrate is exposed.

FIG. 12 is a sectional view schematically showing a preferred example of an optical information recording medium according to the second embodiment of the present invention.

FIG. 13 is a sectional view schematically showing another preferred example of the optical information recording medium according to the second embodiment of the present invention.

FIG. 14 is a cross-sectional view schematically showing another preferred example of the optical information recording medium according to the second embodiment of the present invention.

FIG. 15 is a sectional view schematically showing another preferred example of the optical information recording medium according to the second embodiment of the present invention.

FIG. 16 is a partial cross-sectional view schematically showing a conventional optical information recording medium in which a recording layer is provided up to a tip of an outer end of a substrate.

FIG. 17 is a partial cross-sectional view schematically illustrating a basic structure of a conventionally proposed optical information recording medium (DVD-R).

[Explanation of symbols]

1, 2, 3, 4, 5, 6, 7, 8 Optical information recording medium 10a, 10b, 20a, 20b, 30a, 30b, 4
0a, 40b Holes 11, 21a, 21b, 31, 41a, 41b, 16
1, 171a Disc-shaped substrate 12, 32, 162 Disc-shaped protective plate 13, 13A, 13B, 23a, 23b, 33, 43
a, 43b, 163, 173a Recording layer 14, 24a, 24b, 34, 44a, 44b, 16
4, 174a Reflective layer 15, 25a, 25b, 165, 175a Protective layer 16, 26, 36, 46, 166, 176 Adhesive layer 17a, 17b, 27a, 27b, 37a, 37b, 4
7a, 47b chamfering 18, 19, 28a, 28b, 29a, 29b, 38,
39, 48a, 48b, 49a, 49b Exposed surface 50 Intermediate layer 80 Crimping device 81a, 81b Pressure plate

Claims (10)

[Claims] 1. A disk-shaped substrate having a hole at the center where a recording layer, a reflective layer and a protective layer are provided in this order, or a recording layer, a reflective layer and a protective layer are provided in this order. Sandwich-type optical information recording medium in which a disc-shaped substrate having a hole in the center and a disc-shaped protective plate having the same shape as the substrate are bonded via an adhesive layer such that the recording layer side is inside. 2. The optical information recording medium according to claim 1, wherein an outer peripheral end of an outer surface of at least one substrate is chamfered. 2. Two disks each having a recording layer and a reflective layer provided in this order, having a hole in the center, and chamfering the outer peripheral edge of the outer surface of at least one side of the substrate. Substrate, or a recording layer and a reflective layer are provided in this order, and a disc-shaped substrate having a hole at the center and a disc-shaped protection plate having the same shape as the substrate and at least one side of the outer surface of the substrate. A sandwich-type optical information recording medium in which a disc-shaped substrate and a disc-shaped protective plate each having a chamfered outer peripheral end are bonded via an adhesive layer such that the recording layer side is inside. 3. The method according to claim 1, wherein both the outer edge of the recording layer and the outer edge of the reflective layer on the substrate are receded inward, thereby exposing the outer edge surface of the substrate and bonding the protective layer to the exposed surface. An optical information recording medium according to claim 1. 4. The method according to claim 1, wherein both the recording layer and the reflective layer are retreated outwardly to expose the substrate surface in a region outside the peripheral portion of the hole, and the protective layer is bonded to the exposed surface. 2. The optical information recording medium according to 1. 5. The optical information recording medium according to claim 3, wherein an adhesive layer is further bonded to the exposed surface together with the protective layer. 6. The optical information recording medium according to claim 1, wherein the protective layer is a layer made of a UV curable resin. 7. The method according to claim 7, wherein both the outer edge of the recording layer and the outer edge of the reflective layer on the substrate are receded inward, thereby exposing the outer edge surface of the substrate and bonding the adhesive layer to the exposed surface. 3. The optical information recording medium according to 2. 8. A method in which both the recording layer and the inner end of the reflective layer are receded outward, thereby exposing the substrate surface in a region outside the periphery of the hole, and bonding the adhesive layer to the exposed surface. Item 3. An optical information recording medium according to Item 2. 9. The optical information recording medium according to claim 2, wherein the adhesive layer is a layer made of a UV curable resin. 10. The recording layer according to claim 1, wherein the recording layer is a dye recording layer.
Or the optical information recording medium according to 2.