JPS63239634A - Information recording medium and its production - Google Patents

Abstract

PURPOSE:To permit satisfactory recording by projection of a laser beam having low energy and to prevent generation of uneven recording by joining a resilient disk-shaped resin film having a hole part at the center to a substrate while forming a gas layer to prevent the contact of said film with the recording region of the substrate. CONSTITUTION:Hole parts 13, 17 are provided at the center. An inner circumferential non-recording region 14 and outer circumferential non-recording region 15 are respectively set on the outside of the circumferential edge and the inside of the outer circumferential edge of said hole parts. The resilient disk-shaped resin film 12 provided with the hole part at the center is joined to the respective non-recording regions of the disk-shaped substrate 11 set with the recording region 16 between the respective regions 14 and 15 while the gas layer 18 is formed to substantially prevent the contact of said film with the recording region 16 of the substrate 11. Namely, the gas layer is formed between the substrate 11 and the resin film 12 and the space in which the evaporating as of a recording material at the time of forming the pits diffuses is assured. The recording medium which is suitable for recording of information by projection of the laser beam having the low energy, substantially obviates generation of the uneven recording characteristics and has the uniform recording characteristics is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an information recording medium and a method for manufacturing the same. More specifically, the present invention relates to an information recording medium in which a disc-shaped resin film is bonded to a disc-shaped substrate, and a method for manufacturing the same.

[Technical Background of the Invention] In recent years, information recording media using high energy density beams such as laser beams have been developed and put into practical use. This information recording medium is called an optical disc, and includes video discs, audio discs, large-capacity still image files, and large-capacity computer discs.
A vine used as memory. Optical discs that are generally put into practical use include read-only types and write-once (DRAW) types that allow three recordings.

A typical write-once optical disc has a basic structure including a disk-shaped transparent substrate made of plastic, glass, etc., and a recording layer provided thereon. The surface of the substrate on which the recording layer is provided is coated with an undercoat layer made of a polymeric substance or An intermediate layer may be provided. Furthermore, since the recording layer is easily influenced by the outside world, it has been necessary to protect it from the outside world.

Information is written on the recording layer by, for example, irradiating the recording medium with a laser beam, and the irradiated portion of the recording layer is physically and chemically changed. Currently, as a method for recording information on a recording layer, there is heat mode recording in which the recording layer is irradiated with a laser beam to evaporate the recording material to form bits (small holes).

2. Description of the Related Art In an information recording medium that records information by heat mode recording, a technique has been proposed in which a disk-shaped resin film is bonded to the side of a substrate on which the recording layer is provided, in order to protect the recording layer. (For example, Japanese Patent Publication No. 59-5115).

In heat mode recording, it is preferable to provide a space in which the oxygen necessary for combustion of the recording material or the evaporated gas of the recording material can diffuse during bit formation. Since the film is in contact with the recording layer provided on the substrate, there is no space as mentioned above, and it is not suitable for bit formation by irradiation with a low-energy laser beam.

As a solution to the above problem, a technique is proposed in which a protective film made of a transparent film with unevenness formed on one side on the recording film side of the substrate is provided with a space between the uneven surface and the recording layer so that the uneven surface is in contact with the recording layer. Proposed. (Example: Japanese Patent Publication No. 59/1989 = 36
Publication No. 339).

In this case, the transparent film contacts the recording layer at the convex portions and does not contact the recording layer at the concave portions. Therefore, when a bit is provided in the recording layer by irradiation with a laser beam, the recording material burns and evaporates in the part where the space is formed by the recording layer and the concave part and in the part where the recording layer and the convex part are in contact. There is a difference in the condition of the disc, which results in a difference in recording characteristics.
This may cause uneven recording characteristics.

[Object of the Invention] An object of the present invention is to provide an information recording medium that allows good recording by irradiation with a low-energy laser beam and substantially does not cause uneven recording, and a method for manufacturing the same.

[Summary of the Invention] The present invention has a hole in the center, and an inner non-recording area and an outer non-recording area are set outside the periphery of the hole and inside the outer periphery. A flexible disc-shaped resin film with a hole in the center is substantially in contact with the recording area of the substrate in each of the non-recording areas of the disc-shaped substrate in which the recording area is set between the non-recording areas. The information recording medium is bonded to a substrate while forming a gas layer without any heat loss.

Further, the present invention provides a method for disposing adhesive in a ring shape in each non-recording area of the disc-shaped substrate, and then applying the disc-shaped resin film to the surface side of the substrate where the recording area is set. The area and the resin film are placed on top of each other with a distance between them, and this is heated under pressure to melt or soften and spread the adhesive while maintaining the distance between the recording area of the substrate and the resin film. There is also a method of manufacturing an information recording medium, which comprises bonding a film and a recording area of a substrate so that a gas layer is formed between the film and the recording area of a substrate.

DETAILED DESCRIPTION OF THE INVENTION The invention will now be described in detail with reference to the accompanying drawings. A typical embodiment of the information recording medium of the present invention is shown in FIG.

That is, in FIG. 1, the information recording medium lO of the present invention
is a disc-shaped board! 1 and a disc-shaped resin film 12 is bonded thereto.

The substrate 11 has a hole 13 in the center, and an inner non-recording area 14 and an outer non-recording area 15 are set outside the periphery of the hole 13 and inside the outer periphery, respectively. A recording area 16 is set between them. The resin film 12 has a hole 17 in the center and is flexible. The resin film 12 forms an air layer 18 without substantially contacting the recording area 16 of the substrate 11, and the resin film 12 is attached to the substrate 11 at the joint 19 of the inner non-recording area and the joint 20 of the outer non-recording area. 11.

The information recording medium 10 of the present invention is attached such that the resin film 12 maintains tension due to the air pressure of the air layer 18 and does not come into contact with the recording area 16.

FIG. 2 is a diagram for explaining a method of manufacturing the information recording medium shown in FIG. 1.

That is, in FIG. 2, the substrate 11 has a hole in the center, and an inner non-recording area 14 and an outer non-recording area 15 are set outside the periphery of the hole and inside the outer periphery, respectively. There is a recording area 16 between each non-recording area.
is set.

The resin film 12 has a hole in the center and is flexible. After applying hot melt adhesive 21 and 22 in a ring shape to the inner non-recording area 14 and the outer non-recording area 15 of the substrate 11 using a hot melt dispenser or the like, the recording area 16 of the substrate 11 is set. The resin film 12 is superimposed on the front surface side of the substrate 11 with the recording area 16 of the substrate 11 and the resin film 12 separated from each other. A hot melt adhesive 21.2 is applied to each non-recording area of the substrate 11.
2 is coated on the resin film 12, the resin film 12 is coated with the substrate 1.
They are separated in one recording area 16.

This superimposed substrate 11 and resin film 12 are
Between the receiving jig 24 of the thermocompression bonding machine 23 and the heater block 25 for thermocompression, each hole 13.17 of the substrate 11 and the resin film 12 is passed through the centering 8 rod 26 of the thermocompression bonding machine 13. , the resin film 12 is arranged so as to face the heater block 25. Next, a portion of the resin film 12 corresponding to each non-recording area is heated while being pressurized by the heater block 25, and hot melt adhesive 21 is applied while maintaining a state where the recording area 16 of the substrate 11 and the resin film 12 are separated. .22 is melted or softened and spread to form a recording area 16 on the resin film 12 and substrate 11.
They are joined so that a gas layer (usually an air layer) is formed between them.

Note that the hot melt was applied to the disk-shaped substrate.

The cross section of the adhesive 21, 22 is preferably approximately semicircular, and the thickness when applied is generally 50 μm to 50 μm.
It is in the range of 2 mm, preferably in the range of 100 μm to 1 mm.

Note that the above description describes a preferred method of manufacturing an information recording medium of the present invention, and the present invention is not limited to the above embodiment. For example, as described above, the substrate and the resin film may be placed together on the receiving jig, but they may also be superimposed on the receiving jig. The substrate and the resin film may also be bonded using a device other than a thermocompression bonding machine. Furthermore, although the joint between the substrate and the resin film naturally becomes a non-recording area, the substrate before bonding is provided with a recording layer material all over from the periphery of the hole to the outer periphery, and the recording layer material is also applied to the non-recording area. Materials may be present.

The substrate, recording layer, and film constituting the information recording medium manufactured by the method for manufacturing an information recording medium of the present invention include:
Since publicly known ones can be used at will, regarding these,
A brief explanation is given below.

First, the substrate used in the present invention can be arbitrarily selected from various resin materials conventionally used as substrates for information recording media.

Examples of substrate materials include cell-cast polymethyl methacrylate, injection-molded polymethyl methacrylate, and polymethyl acrylate in terms of substrate optical properties, flatness, processability, handling, stability over time, and manufacturing costs. Preferred examples include acrylic resins; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; amorphous polyolefin resins; and synthetic resins such as polycarbonates. Among these, preferred are polymethyl methacrylate, polycarbonate, and epoxy resin in terms of dimensional stability, transparency, and flatness.

The surface of the substrate on which the recording layer is provided has improved flatness,
For the purpose of improving adhesive strength and preventing deterioration of the recording layer, an undercoat layer (and/or intermediate layer) may be provided.

Examples of materials for the undercoat layer (and/or intermediate layer) include polymeric substances such as polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, nitrocellulose, polyethylene, chlorinated polyolefin, polypropylene, and polycarbonate; silane cups; Examples include organic substances such as ring agents; and inorganic substances such as inorganic oxides (Si02, A1□03, etc.) and inorganic fluorides (MgFz).

Examples of materials used for the recording layer include TB, Zn, I
n, Sn, Zr, An%Ti%Cu.

Examples include metals such as Ge, 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. Alternatively, combinations of dyes, dyes and polymers, and dyes and the aforementioned metals and metalloids can also be used.

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

The recording layer can be formed on the substrate directly or via an undercoat layer by using the above-mentioned materials by vapor deposition, sputtering, ion blasting, coating, or the like. The recording layer may be a single layer or m layers, but its layer thickness is generally in the range of 100 to 5,500 λ, preferably in the range of 150 to 1,000 λ, in view of the optical density required for optical information recording.

Note that the surface of the substrate opposite to the side on which the recording layer is provided is coated with inorganic substances such as silicon dioxide, tin oxide, and magnesium fluoride to improve scratch resistance and moisture resistance.
A thin film made of a polymeric substance such as a thermoplastic resin or a photocurable resin may be provided by a method such as vacuum deposition, sputtering, or coating.

The material of the disc-shaped resin film is acrylic resin,
Examples include thermoplastic resins such as vinyl chloride resin, polystyrene resin, polyamide resin, polyolefin resin (eg, polypropylene, polyethylene), polycarbonate, polyester resin, nylon, and polyvinylidene chloride. Also, the thickness of the resin film is 10
~500μm, and the preferred range is 50~1
00 μm.

[Effects of the Invention] The information recording medium of the present invention has a gas layer formed between the substrate and the resin film, and a space is secured for the evaporated gas of the recording material during bit formation to diffuse. It is also suitable for recording information by irradiating energy with a laser beam. Further, since there is no part in the recording area that is in contact with the resin film, there is substantially no unevenness in recording characteristics, and uniform recording characteristics can be obtained. Furthermore, since the resin film maintains tension due to the pressure of the gas layer, damage to the recording layer by the resin film is significantly reduced.

In the method for manufacturing an information recording medium of the present invention, the adhesive placed in each non-recording area of the substrate is melted or softened and spread, so when the substrate and resin film are stacked, the gas in the gas layer formed in advance is released. The resin film can be bonded to the substrate without leaking to the outside.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the information recording medium of the present invention. FIG. 2 is a cross-sectional view for explaining the method for manufacturing an information recording medium of the present invention. 10: Information recording medium 11: Disc-shaped substrate 12: Disc-shaped resin film 13. 17: Hole 14: Inner non-recording area 15: Outer non-recording area 16: Recording area 18: Air layer 19. 20: Bonding Parts 21 and 22: Hot melt adhesive 23: Thermocompression bonding machine 24: Receiving jig 25: Heater block 26: Center alignment core frame

Claims (1)

[Claims] 1. A hole is provided in the center, an inner non-recording area and an outer non-recording area are set outside the periphery of the hole and inside the outer periphery, and a recording area is provided between each of the non-recording areas. A flexible disc-shaped resin film with a hole in the center is placed in each of the non-recording areas of the set disc-shaped substrate while forming a gas layer without substantially contacting the recording area of the substrate. An information recording medium that is bonded to a substrate. 2. 2. The information recording medium according to claim 1, wherein the cross section of the disc-shaped resin film bonded to the disc-shaped substrate has an arc shape in a portion corresponding to the recording area. 3. A hole is provided in the center, an inner non-recording area and an outer non-recording area are set outside the periphery of the hole and inside the outer periphery, and a recording area is provided between each of the non-recording areas. After placing adhesive in a ring shape on each non-recording area of the set disc-shaped substrate, a flexible disc-shaped resin film with a hole in the center is placed on the front side of the board where the recording area is set. , the recording area of the substrate and the resin film are placed on top of each other with a distance between them, and this is heated under pressure to melt or soften and spread the adhesive while maintaining the distance between the recording area of the substrate and the resin film. A method for manufacturing an information recording medium, which comprises bonding the resin film and the recording area of the substrate so that a gas layer is formed between the resin film and the recording area of the substrate. 4. After applying hot melt adhesive in a ring shape to each non-recording area of the disk-shaped substrate, apply the disk-shaped resin film to the front side of the substrate where the recording area is set, so that the recording area of the substrate and the resin film are in contact with each other. The resin film is placed on the heater block between the receiving jig and the heater block of a thermocompression bonding machine, which is equipped with a receiving jig and a heater block for thermocompression bonding. The parts of the resin film corresponding to each non-recording area are heated under pressure using a heater block, and the hot melt adhesive is melted or heated while maintaining the distance between the recording area of the substrate and the resin film. 4. The method for manufacturing an information recording medium according to claim 3, which comprises softening and spreading the resin film and joining the recording area of the substrate so that a gas layer is formed between the resin film and the recording area of the substrate. 5. 5. The method of manufacturing an information recording medium according to claim 4, wherein the hot melt adhesive applied to the disk-shaped substrate has a substantially semicircular cross section.