JPH0223548A - Information recording medium - Google Patents

Abstract

PURPOSE:To obtain the information recording medium which is free from curling by joining two sheets of information recording disks at the substrates on which the recording layers are not provided to each other. CONSTITUTION:Primer coating layers 12a, 12b are provided on the flexible resin substrates 11a, 11b and the recording layers 13a, 13b, adhesive layers 14a, 14b and tracking layers 15a, 15b having servo pits are laminated in this order thereon. Two sheets of such information recording disks are joined via an adhesive layer 16 on the substrates 11a, 11b side surfaces. Two sheets of the information recording disks are joined by disposing the surfaces thereof on which the recording layers 13a, 13b are not provided to face each other in such a manner, by which the internal stresses possessed by the information recording disks are offset. The information recording medium which is free from curling is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an information recording medium comprising a recording layer that allows information to be read, written and/or erased by a laser.

More specifically, the present invention relates to an information recording medium in which the recording layer is formed on the surface of a flexible resin film.

[Technical Background of the Invention] In recent years, disc-shaped information recording media that use high energy density beams such as laser beams have been developed and put into practical use. This information recording medium is called an optical disk, and can be used as a video conference disk, an audio conference disk, a large capacity still image file, and a large capacity computer disk memory.

The basic structure of an optical disk is a disk-shaped transparent substrate made of plastic or the like, and a recording layer provided thereon from which information can be read, written, and/or erased. The surface of the substrate on which the recording layer is provided is coated with an undercoat layer or an intermediate layer made of a polymeric material in order to improve the flatness of the substrate, improve the adhesion with the recording layer, and improve the sensitivity of the optical disc. Sometimes it is provided.

In recent years, disc-shaped information recording media (optical discs) have been developed in which a flexible resin film is used as a substrate and the recording layer is formed thereon.

Information recording media using such flexible resin films are rotated at high speed to write, read, or erase information in the same way as conventional video discs, audio discs, etc.; Since the thickness of the substrate is thinner than that of conventional substrates, it has advantages such as relatively low manufacturing cost.

However, curling occurs in flexible information recording media due to internal stress that occurs when forming recording layers, protective layers, etc. using a flexible resin film by vacuum evaporation or sputtering. There are problems such as adverse effects on the flying characteristics during rotation.

In order to prevent the above-mentioned curling, - If recording layers, etc. are provided on both sides of the above-mentioned flexible substrate, adjust the recording layers, etc. to the same thickness on both sides, or apply an undercoat layer, etc. In some cases, it was difficult to apply the same coating to both sides. Also,
The conventional method of forming films on both sides, which has been improved to prevent these problems, requires large-scale film forming equipment to provide the recording layer, etc., resulting in high costs for the resulting information recording medium. Moreover, it cannot be said that it is easy to provide the above-mentioned recording layer etc. in the same way on both sides, and it cannot be said that it is a highly productive method.

[Objective of the Invention] The present invention aims to provide an information recording medium in which substantially no curling occurs on the substrate of the information recording medium, or the occurrence of curling is significantly reduced, and the rotational characteristics during driving are good. purpose.

[Summary of the Invention] The present invention provides an information recording disk comprising a recording layer on one surface of a substrate made of a flexible resin film, from which information can be read, written and/or erased by a laser. There is an information recording medium in which the two substrates are joined with the surfaces of the substrates on which no recording layer is provided facing each other.

Preferred embodiments of the information recording medium of the present invention are as follows.

l) The above-mentioned information recording medium, wherein the material of the above-mentioned substrate is polyolefin resin, polycarbonate, or polyester resin.

2) The above-mentioned information recording medium, wherein the thickness of the above-mentioned substrate is within a range of 1O to f50gm.

3) The information recording medium described above, further comprising a tracking guide layer provided on the recording layer.

4) The above-mentioned information recording medium, characterized in that an undercoat layer is provided between the above-mentioned substrate and the recording layer.

[Effects of the Invention 1] The information recording medium of the present invention comprises two information recording disks each having a recording layer etc. provided on one surface of a substrate made of a flexible resin film. It has a structure in which the two surfaces facing each other are joined together.

In an information recording disk in which a recording layer or the like is provided on one surface of the disk, for example, an information recording disk wound into a roll, all portions have approximately the same internal stress and curl. By joining two such information recording disks together using substrates that are not provided with a recording layer, it is possible to offset the internal stress of each information recording disk, thereby creating an information recording medium with less curl. It turns out that you can get it. Furthermore, since the information recording medium of the present invention has extremely little curl, it has excellent rotational characteristics during driving.

Further, the information recording medium of the present invention can be manufactured simply and with high precision using a conventional manufacturing method, and therefore it can be said that it can be obtained by a method with excellent productivity.

[Detailed Description of the Invention] The information recording medium of the present invention is basically an information recording medium in which a recording layer is provided on one side of a substrate made of a flexible resin film that allows information to be recorded and reproduced using a laser. It is a recording medium. It is made by joining two information recording media, each of which has a recording layer, etc. on one surface of a substrate made of a flexible resin film, with the surfaces of the substrates that are not provided with the recording layer, etc. facing each other. be.

Conventionally, as mentioned above, information recording media obtained by forming a recording layer, a protective layer, etc. using a flexible resin film by vacuum evaporation or sputtering have suffered from internal stress generated when forming the recording layer, etc. As a result, curls occur in the flexible information recording medium,
This has caused problems such as having a negative effect on the flying characteristics during rotation. The occurrence of internal stress, which is the cause of the above-mentioned curl, occurs even when a recording layer, etc., such as a dye layer, is provided by a coating method.
This naturally occurs during the drying process.

In order to prevent the occurrence of such curls, the present inventors
Research has been carried out in order to obtain a flexible information recording medium that is less prone to curling by a method that is simple and highly accurate, and therefore has excellent productivity. In particular, in the conventional method of providing a recording layer, etc. on both sides of the original plate to maintain curl balance, it is necessary to adjust the thickness of the recording layer, etc. to be the same on both sides, and when applying an undercoat layer, etc., the thickness must be the same on both sides. The present invention has been achieved through repeated research, focusing on the fact that it is difficult to apply the same and the above-mentioned method cannot be said to be a highly productive method.

As described above, the information recording medium of the present invention comprises two information recording media each having a recording layer on one surface of a substrate made of a flexible resin film, on which information can be read, written and/or erased using a laser. have a structure in which the surfaces of the substrates on which the recording layer is not provided are opposed to each other and are bonded to each other.

The configuration of the information recording medium of the present invention will be explained with reference to FIG.

FIG. 1 is a partial sectional view schematically showing an example of the information recording medium of the present invention.

In FIG. 1, undercoating layers 12a and 12b are provided on flexible resin substrates 11a and 11b for smoothing the surfaces, and recording layers 13a and 13b and adhesive layers 14a and 14b are provided thereon.
, a tracking guide layer 15a having servo pits,
Reference numeral 15b indicates an information recording medium in which two information recording disks stacked in this order are joined at the surface on the substrate side via an adhesive layer 16.

The information recording medium of the present invention has flexible resin substrates 11a, l.
It is necessary at least to provide recording layers 13a and 13b on the recording layer 1b, and a tracking guide layer 1 having servo bits is necessary for controlling tracking.
5a and 15b are preferably provided, and undercoat layers 12a and 12b for smoothing the surface are preferably provided.

In addition, in order to improve durability, the information recording medium of the present invention is provided with adhesive layers 14a and 14b as desired.Other than the recording layer provided on a flexible resin substrate, other layer structures are not included. It is not limited to the above.

In the present invention, an information recording disk is obtained by laminating the above-mentioned Q layer etc. on a flexible resin substrate by a conventional manufacturing method, and then the information recording disk is bonded on the surface of the substrate side via an adhesive layer 16. In the present invention, an undercoat layer, a protective layer, etc. may be provided by coating using a commonly used roller or the like.
Even if there is a back side of the coating liquid, the back side is only used for adhesion and does not pose a problem. Similarly, when providing a recording layer etc. using vapor deposition, careful consideration is required for the back side. I don't. In this way, an information recording disk having a recording layer etc. laminated on one side of the substrate is obtained. The thickness of the flexible resin substrate used to manufacture this information recording disk is thinner than conventional substrates because the two substrates are bonded in a later process. The thickness is 10~
It is preferably within the range of 5004 m, more preferably 1
It is within the range of 0 to 150 gm. Naturally, the information recording disk obtained above is curled due to internal stress during formation of the recording layer and the like.

However, the information recording disk, for example, the information recording disk wound into a roll, has almost the same internal stress in all parts and curls occur. Therefore, by joining two such information recording disks to each other using substrates that are not provided with a recording layer, the internal stress of the information recording disks is canceled out, and an information recording medium without curling can be obtained. .

The two information recording disks are joined together by laminating the films of the information recording disks wound into a roll using an adhesive. Lamination can be performed by a known method. As an adhesive,
Examples include hot melt adhesives, solvent-free adhesives, and reactive adhesives. Preferably it is a hot melt adhesive.

The information recording medium of the present invention can be manufactured by rolling the laminated information recording medium around a roller and punching it out into a disk shape as described above.

Note that the above description describes one embodiment of the information recording medium of the present invention, and is not limited to the above embodiment.

As the resin film, recording layer, undercoat layer, etc. constituting the information recording medium of the present invention, known ones can be arbitrarily used except for the parts that are characteristic of the present invention, so these will be briefly described below. explain. Materials for the disc-shaped resin film used in the present invention include acrylic resin, vinyl chloride resin, polystyrene resin, polyamide resin, polyolefin resin (e.g. polypropylene, polyethylene), polycarbonate, polyester resin (e.g. (polyethylene terephthalate), and thermoplastic resins such as polyvinylidene chloride. Preferably, polyolefin resin, polycarbonate or polyester 4#l [l] is used.

The surface of the substrate on which the Q layer is provided has improved planarity,
An undercoat layer (and/or intermediate layer) may be provided for the purpose of improving adhesive strength and preventing deterioration of the recording layer.
and/or intermediate layer), for example, polymeric substances such as polymethyl methacrylate, acrylic acid-clouded methacrylic acid copolymer, nitrocellulose, polyethylene, chlorinated polyolefin, polypropylene, polycarbonate; acrylic monomers, etc. UV curing type 4
11 fats; organic substances such as silane coupling agents; al-free compounds (S f O2, /Ml, O.

etc.), and inorganic substances such as inorganic fluoride (MgFz). Using the above materials, for example, a layer made of UV curable resin may be provided as an undercoat layer, and an inorganic oxide layer may be further provided thereon as an intermediate layer, or the above materials may be combined to form a single layer. More than one layer can be provided as appropriate.

In the present invention, the recording layer formed on the information recording medium is of a type (write-once type or DRAW [Direct Read
After Write type), and a type that allows repeated recording and erasing by utilizing phase change or change in the direction of magnetization in the case of magneto-optical recording (Erasable OT waterfall type, that is, E-DRAW).
-Direct Read After Write
There is a type).

Examples of materials used for the DRAW type recording layer include T.
e, Zn, I n, Sn, Zr, An, Ti, Cu, G
Examples include metals such as e, Au, and Pt; metalloids such as Bi, As, and Sb; semiconductors such as Si; and alloys thereof or combinations thereof. Compounds such as sulfides, oxides, borides, silicon compounds, carbides, and nitrides of these metals, semimetals, or semiconductors; and mixtures of these compounds and metals can also be used in the recording layer.

The recording layer may further contain various known metals, semimetals, or compounds thereof as recording layer materials.

Alternatively, the recording layer may be made of a dye such as a cyanine dye.

The recording layer may be a single layer or a multilayer, and the thickness of the recording layer is generally from 100 to 50 mm in terms of optical density required for optical information recording.
It is in the range of 500 or more, preferably in the range of 150 to too much.

Further, when the recording layer is of the E-D RAW type, a recording layer made of the following material, which is a substance that can undergo a phase change due to temperature, is provided. At this time, a light-absorbing substance may be dispersed and contained if necessary.

Examples of the phase change include a change between a crystalline state and an amorphous state, a change between a compatible state and a phase-separated state, and the like.

Examples of substances that can change state between crystalline and amorphous states are 5b2Se, Tea, (.

<x<2), As-Te-Ge-based, 5n-Te-Se-based, and other metal and semimetal compounds. For example, Sb and Se are relatively in a crystalline state at room temperature and have high reflectance and low transmittance, but at high temperatures they become amorphous, resulting in lower reflectance and higher transmittance. On the contrary, Te
a is in an amorphous state at room temperature and becomes crystalline at high temperature. In addition to these, known metals, metalloids, and compounds thereof that undergo a state change between a crystalline state and an amorphous state can be used.

Furthermore, a typical example of a substance that can undergo a state change between a compatible state and a phase-separated state is a polymer blend consisting of a mixture of two or more types of polymers. However, a combination of a polymer and a monomer may exhibit similar behavior, and such a composition is also included in the polymer blend in the present invention.

As the material used for the magneto-optical recording layer (perpendicular magnetization I8), GdFeCo, TbFeC0, etc. can be used.

If the recording layer is made of a metal or the like, or if the substance that can cause a phase change is an inorganic substance such as the metal,
It can be formed on the substrate by vapor deposition, sputtering, or ion blasting on the substrate surface. The recording layer may be a single layer or a multilayer, but its layer thickness is generally 100-15 mm in terms of optical density required for optical information recording.
000x, preferably 150 to 100OX.

In addition, when the recording layer is an organic compound such as a dye or the above-mentioned polymer blend, a coating solution is prepared by dissolving the substance and, if necessary, a light-absorbing substance in an appropriate solvent, and this coating solution is coated with a spin code method. It can be formed on a substrate by applying it to the surface of the substrate by a coating method such as a roll coating method and then drying it.

It is preferable that a tracking guide layer is provided on the recording layer, especially in order to improve tracking performance during recording.The material for forming the tracking guide layer is as follows:
Photographic halogenated emulsions are used. Servo marks and the like are formed on the tracking guide layer to perform tracking control.

Further, if desired, an adhesion layer made of a silane coupling agent or the like may be provided in order to improve the adhesion between the recording layer and the protective layer.

For the purpose of physically and chemically protecting the recording layer on the tracking guide layer or between the recording layer and the tracking guide layer, inorganic substances such as Si02, MgF2.5n02 or organic substances such as UV curable resin are used. A protective layer may be provided.

In addition, silicon dioxide, tin oxide, magnesium fluoride, etc. may be added to the substrate side of the recording layer, on both sides of the recording layer, or on the surface opposite to the substrate, in order to improve the scratch resistance, moisture resistance, and prevention of deformation and deterioration of the recording layer. A thin film made of an inorganic substance such as zinc sulfide or the like may also be provided.

In addition, the substrate side of the second layer or the surface opposite to the substrate is coated with metals such as Cr and Ni for the purpose of improving the S/N ratio during information reproduction and improving the sensitivity during recording. A light reflecting layer may be provided.

Next, Examples and Comparative Examples of the present invention will be described. However, the following items do not limit the present invention.

[Example 1] An undercoat layer with a thickness of 800 μm was formed on a belt-shaped (web-like) polyethylene terephthalate film with a thickness of 33 μm. i
UV curing resin (UV-3070: manufactured by Three Pond)
was applied using a roll.

A layer of zinc sulfide was formed thereon by electron beam evaporation to a layer thickness of 700 mm. Furthermore, a reversible amorphous-crystalline phase change was caused by laser irradiation, and an S b 52 T e 411 layer was formed to a thickness of 700 mm as an erasable and rewritable recording layer by a binary simultaneous vapor deposition method. Furthermore, a layer of zinc sulfide was formed on this recording layer by electron beam evaporation to a layer thickness of 1500 mm.

Next, a silane coupling agent (K
BM-403: Shin-Etsu Chemical Co., Ltd. M) Nol, i [(amount % (solvent: isopropanol)) is applied using a roll, and then a photographic halogenated emulsion (mainly containing gelatin monosilver bromide) is applied on top of the coating. was coated using a roll to a dry layer thickness of 14 m, pattern exposure, development and fixing were performed to form a tracking guide layer having servo marks.

This was done by attaching two of the information recording disks obtained above into a roll and a hot melt adhesive to a laminator, and laminating the film onto the substrates on which no recording layer etc. were provided using the adhesive. . The adhesive layer was lOALm.

Next, the film with the two information recording disks bonded together was punched out into a disc shape with an outer diameter of 86 mm and an inner diameter of 25 mm to produce an information recording medium.

[Comparative Example 1] In Example 1, the thickness was 75 gm instead of 334 m.
Information was obtained in the same manner as in Example 1, except that a strip-shaped (web-shaped) polyethylene terephthylate film was used, and all layers from the undercoat layer to the tracking guide layer were provided on both sides of the film. A recording medium was manufactured.

The following curl measurements were carried out on 40 information recording media using the above-mentioned methods, and those with a curl amount of inm or less were regarded as acceptable products, and the yield was calculated.

Knee > k did.

The above results are shown in Table 1.

Table 1 Yield (%) Example 1 Comparative Example 1 The information recording medium of the present invention can be manufactured with high precision by a simple method. can be obtained efficiently.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an example of the information recording medium of the present invention. Flexible resin substrate undercoat layer: 12a, recording layer: 13a, adhesive layer: 14a, tracking guy adhesive layer: 16: lla, 11b 2b 3b 4b de layer: 15a,

Claims (1)

[Claims] 1. Two information recording disks each having a recording layer on one surface of a substrate made of a flexible resin film that allows information to be read, written and/or erased using a laser, provided with the recording layer of the substrate. An information recording medium that is bonded with its unfinished surfaces facing each other.