JPH02137140A - Information recording medium - Google Patents

Abstract

PURPOSE:To improve sensitivity by using a film where fine projecting and recessed parts are provided on the surface on a side opposed to a recording layer and finer projecting and recessed parts are provided on the surface of the above-mentioned projecting part for a resin film as a protective film. CONSTITUTION:The flexible disk-like resin film 12 where the fine projecting and recessed parts are provided on the surface of the side opposed to the record ing layer 20 and the finer projecting and recessed parts than the above- mentioned projecting and recessed parts are provided on the surface of the projecting part is bonded on the non-recording areas 18 and 19 on the inner circumferential side and the outer circumferential side of the resin substrate 11 and a space part 22 is formed by the substrate 11 and the resin film 12 having the projecting and recessed parts. Therefore, the space part 22 is secured by the projecting and recessed parts which are fine but larger than the other projecting and recessed parts and the contact area with the substrate 11 is made smaller by the finer projecting and recessed parts. Thus, the energy at the time of recording is reduced and the recording characteristic such as sensitiv ity, etc., is improved.

Description

[Detailed description of the invention] [Field of invention] The present invention relates to an information recording medium.

More specifically, the present invention relates to an information recording medium in which a disc-shaped resin film is bonded to a disc-shaped resin substrate [Technical Background of the Invention] In recent years, information recording media that use high-energy density beams such as laser beams have become popular. 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.
It is used as memory.

The basic structure of an optical disk is a disc-shaped transparent substrate made of plastic, glass, or the like, and a recording layer provided thereon. On the surface of the substrate on which the recording layer is provided,
In order to improve the flatness of the substrate, improve the adhesion to the recording layer, or improve the sensitivity of the optical disc, an undercoat layer or intermediate layer made of a polymeric substance is sometimes provided.

Furthermore, since the recording layer is easily influenced by the outside world, it is necessary to protect it from the outside world. For this reason, in recent years, a technique has been proposed in which a disk-shaped resin film is bonded to the side of the substrate on which the recording layer is provided.

Generally, resin films are bonded on the inner and outer circumferential sides of the substrate. A space sealed with a resin film is formed in a portion of the recording layer between the inner circumferential side and the outer circumferential side of the substrate. Japanese Patent Publication No. 59-3633
Publication No. 9 states that a film having unevenness on one side in contact with the recording layer is used as the resin film. For example, when a metal material is used as the recording layer, the metal evaporates during laser beam irradiation for recording etc. , a space is required for scattering, and when an organic substance such as a dye is used, a space is required for holding oxygen for combustion and for dissipating combustion gas. Since the resin film used in the above publication has irregularities on its surface, it is said that it is possible to secure a space for the evaporation and scattering of the metal or a space for the dissipation of combustion gas such as a dye.

The above-mentioned protective film made of a resin film having unevenness is superior to the conventional air sandwich type in which the substrates are bonded to each other via a spacer in that the substrate is less likely to warp and is easy to manufacture. Furthermore, compared to conventional protective layers, it has the advantage that the substrate is less likely to warp and the space can be secured.

However, if the unevenness of the resin film is large, a space for evaporation, etc. can be secured, but the contact area between the recording layer and the convex portion becomes relatively large.
Heat conduction tends to occur easily, and characteristics such as sensitivity during recording tend to deteriorate. In addition, when the unevenness is small, contrary to the above, the contact surface between the recording layer and the convex part is small, but the space is insufficient, so the evaporated components and combustion gas cannot be accommodated in the space, and the resin film The energy must be absorbed into extremely small holes, and a large amount of energy is required during recording. Therefore, in this case as well, there is a problem in that characteristics such as sensitivity during recording tend to deteriorate as in the case where the unevenness is large.

[Objective of the Invention 1] The present invention has excellent storage stability, such as virtually no warping or distortion of the substrate, and significantly reduced intrusion of dust into the recording layer formed on the substrate, and a recording medium. The purpose is to provide an information recording medium with excellent recording characteristics such as sensitivity.

[Summary of the Invention] The present invention provides an inner non-recording area and an outer non-recording area in which a hole is provided at the center and a recording layer is set outside the periphery of the hole and inside the outer periphery, respectively. A disk-shaped resin substrate provided in an area other than the recording layer has a hole in the center on the surface thereof, and has minute irregularities on at least the surface facing the recording layer, and at least the convexity of the irregularities. A flexible disk-shaped resin film having microscopic irregularities on the surface of the resin substrate is bonded to the non-recording area on the inner circumferential side and the non-recording area on the outer circumferential side of the resin substrate. It is on an information recording medium.

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

l) An information recording medium characterized in that the height of the minute irregularities is in the range of 5 to 100 #Lm, and the interval thereof is in the range of 100 to 3000 μm.

2) The height of the finer unevenness mentioned above is 0°5~5μ
An information recording medium characterized in that the distance is in the range of m and the interval is in the range of 1 to 1100p.

3) An information recording medium characterized in that the resin film is bonded to the inner non-recording area and the outer non-recording area of the resin substrate in a ring shape or a discontinuous ring shape. .

4) The information recording medium described above, wherein the discontinuous bonding is performed in a plurality of island-like bonding portions formed at intervals.

5) The information recording medium described above is characterized in that the discontinuous bonding is performed in a large number of substantially concave-shaped island-like bonded portions formed at substantially concave intervals.6) A large number of The interval between the approximately concave-shaped island joints is 0.1 to 2.
The information recording medium according to 5) above, characterized in that the information recording medium is within the range of mm.

7) The above-mentioned information recording medium, characterized in that only the bonding area on the inner circumferential side is made up of a large number of island-shaped bonding portions formed at intervals.

[Effects of the Invention] The information recording medium of the present invention has minute irregularities on the surface of the resin film as an M-retaining film on the side facing the recording layer, and further has minute irregularities on the surface of at least the convex portions of the irregularities. A material with roughness is used. As a result, when pits are formed during recording, even if the resin film and the recording layer come into contact, it is only a minute point contact and heat is difficult to diffuse, making it possible to form bits and the like with little energy. can. Therefore, the present invention is an information recording medium with extremely high sensitivity and almost no recording errors.

That is, by using the resin film of the present invention,
Although the space formed by the unevenness and the recording layer is large, the contact area between the resin film and the substrate is small. The contact area with the substrate can be further reduced.

By securing the above-mentioned space in this way, when a metal material is used as the recording layer, it is possible to obtain a space for the metal to evaporate and scatter during laser beam irradiation for recording, etc., and also for dyes, etc. If organic materials are used, space can be obtained for retaining oxygen for combustion and for dissipating combustion gases. This allows the energy during recording to be reduced, thereby making it possible to improve recording characteristics such as sensitivity. In addition, since the contact area with the substrate can be reduced by using smaller irregularities, it is possible to reduce energy loss due to heat conduction during recording, so it is possible to increase the sensitivity during recording, similar to the above-mentioned provision of space. It is possible.

In particular, when the resin substrate and the resin film are bonded using ultrasonic fusion and heat fusion, either alone or in combination, and a large number of evenly distributed ventilation holes are formed, the external pressure may change. However, the expansion of the space formed by the resin substrate and the resin fin '1 is the original t! Warpage and distortion of the substrate, which often occur, can be substantially prevented from occurring. In addition, since the ventilation holes are minute, peeling of the resin film and the intrusion of dust into the recording layer formed on the resin substrate are significantly reduced, making it possible to maintain good recording characteristics over a long period of time. It is possible.

[Detailed Description of the Invention 1 The present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show preferred embodiments of the information recording medium of the present invention. The information recording medium 10 of the present invention is formed by bonding a disc-shaped resin film 12 to a disc-shaped resin substrate 11. It is something. FIG. 1 is a plan view of the information recording medium 10 of the present invention viewed from the side to which the resin film 12 is bonded.

The resin film 12 has a hole 13 in the center, and is bonded by forming a ring-shaped inner bonding area 14 and an outer bonding area 15 in an area corresponding to the non-recording area of the resin substrate 11. . The joining of the joining area 14 on the inner peripheral side is between the road and the
It is made up of a large number of substantially concave-shaped elongated island-like joints 16 formed at intervals of .

FIG. 2 is an enlarged sectional view of the information recording medium 10 of the present invention taken along line II in FIG. 1.

The disc-shaped resin substrate 11 has a hole 17 in the center, and an inner non-recording area 18 and an outer non-recording area 19 are set outside the periphery of the hole 17 and inside the outer periphery, respectively. A recording layer 20 is formed between the non-recording areas on the inner circumferential side and the outer circumferential side.

The disc-shaped resin film 12 is bonded to the bonding area 1 by ultrasonic welding in the non-recording area 18 on the inner peripheral side of the resin substrate 11.
4 is formed and bonded, and the bonding area 1 is bonded by a heat fusion method in the non-recording area 19 on the outer peripheral side of the resin substrate 11.
5 is formed and joined. A space 22 is formed by the resin substrate 11 and the resin film 12 having irregularities.

The information recording medium of the present invention has a characteristic feature of a flexible disc-shaped resin film 12 having minute irregularities on its surface and having minute irregularities on at least the convex portions of the irregularities. In order to explain the effect, the surface condition of the disk-shaped resin film 12, the contact condition between the disk-shaped resin film 12 and the recording layer 20 on the resin substrate 11, and the disk-shaped resin film 1.2 and the recording layer 20 will be explained. FIG. 3 shows a space 22 formed by A of FIG.
It is an enlarged view of the part.

As can be seen from FIG. 3, by using the resin film of the present invention, the contact area between the resin film and the substrate is small despite the large space 22, that is, the contact area between the resin film and the substrate is small. Secure the space 22,
The contact area with the substrate can be further reduced by making the unevenness smaller.

By securing the above-mentioned space 22 in this way, when a metal material is used as the recording layer, a space can be obtained for the metal to evaporate and scatter during laser beam irradiation for recording, etc. When using organic materials, space can be obtained for retaining oxygen for combustion and for dissipating combustion gases. This allows the energy during recording to be reduced, thereby making it possible to improve recording characteristics such as sensitivity. In addition, since the contact area with the substrate can be reduced due to the finer unevenness, energy loss due to heat conduction during recording can be reduced, and as with the above-mentioned space, it is possible to increase the sensitivity during recording. It is possible.

The height of the minute (minute but relatively large) irregularities provided on the surface of the resin film is 5 to 1100 JL.
(particularly preferably in the range of lO to 50 lm), and the spacing thereof is preferably in the range of 100 to 3000 gm (particularly preferably in the range of lO to 50 lm), and the above-mentioned finer unevenness is , its height is 0.5
It is preferable that the distance is in the range of ~5 pm (particularly preferably in the range of 3 JLm per weight), and the interval is preferably in the range of 1 to 11007z (particularly preferably in the range of 3 to 50 JLm).
), the thickness of the resin film is 10 to 5004
m range is preferred, particularly preferably 50 to 200 m
is within the range of

Note that, as shown in FIG. 1, the bonding in the bonding area 14 on the inner circumferential side is performed by a plurality of elongated island-like bonding portions 16 formed radially from the center of the substrate 11 with distances between the paths. It is preferable that one ventilation hole (non-fused part) 21 be formed between the island-like joint parts 16. By doing this, the resin substrate 11 and Air can circulate between the space 22 formed by the resin film 12 and the outside. The distance between adjacent island joints is usually within the range of 0.01 to 3 mm, preferably within the range of 0.1 to 2 mm. More preferably, it is within the range of 0.2 to inm.

Furthermore, in an information recording medium using a resin film with uneven surfaces formed on both sides, scratches on the resin film surface, attached fingerprints, and dust become less noticeable. Furthermore, when stacked one on top of the other, it will not stick to other information recording media.

The information recording medium IO of the present invention has the above-mentioned structure, and a method for manufacturing the same will be described below with reference to FIGS. 4 and 5 of the accompanying drawings.

A flexible disc-shaped resin film 12 with a hole 13 in the center and uneven surfaces on both sides, a non-recording area 18 on the inner circumference □ side and a non-recording area on the outer circumference side, with a hole 17 in the center. A disc-shaped resin substrate 11 on which a recording layer 20 is formed between 19 and 19 is superimposed on the surface of the recording layer 20 side. An ultrasonic welding machine 40 equipped with an application horn 41 at a position corresponding to the non-recording area 18 on the side and a jig 42 are installed.
The resin film 12 is placed between the two and facing the application horn 41 .

The application horn 41 has a ring-shaped convex portion 4 for applying ultrasonic waves at a position corresponding to the non-recording area 18 on the inner peripheral side of the resin substrate 11.
At the tip of the ring-shaped convex portion 43, a large number of wedge-shaped protuberances 44 are further formed radially with respect to the center of the application horn 41 at substantially concave intervals.

In the ultrasonic fusion splicer 40 , ultrasonic waves are generated from an ultrasonic oscillator 45 and transmitted to an application horn 41 via a converter 46 . Fusion bonding is performed by lowering the application horn 41, pressurizing the resin film 12 with the bulge 44 formed at the tip of the ring-shaped convex portion 43 of the application horn 41, and applying ultrasonic waves while maintaining this state. As a result, the resin film 12 is fused and bonded to the substrate 11.

When the resin film 12 is pressurized, the portions corresponding to the protuberances 44 are fused and bonded by ultrasonic waves.

Therefore, an island-like joint is formed at the tip of the ring-shaped convex portion 43 in a portion corresponding to a large number of wedge-shaped protuberances 44 formed radially from the center of the application horn 41 at substantially concave intervals.

Since a large number of protuberances are formed at the tip of the ring-shaped convex portion with a distance between the grooves and the force, the spacing between the protuberances is necessarily narrow, making it suitable for forming fine ventilation holes.

Next, as shown in FIG. 5, the resin substrate 11 is fused using a heat fusion machine 50 equipped with a heater block 52 in which a ring-shaped convex portion 51 is formed at a position corresponding to the non-recording area 19 on the outer peripheral side of the resin substrate 11. Perform bonding.

The heater block 52 is supplied with power from the power supply line 53 and generates heat. The power supply line 53 is connected to the heater block 5 in order to prevent uneven heat generation from the heater blower 52.
It is preferable to connect the wires at symmetrical positions of 2. For fusion bonding, the heating block 52 that generates heat is lowered, and the resin film 12 is pressurized with the tip of the ring-shaped convex portion 51.
The resin film 12 is fused and bonded to the resin substrate 11.

The resin film 12 is fused and bonded at a portion corresponding to the ring-shaped convex portion 51 .

In this case, since no protuberance is formed at the tip of the ring-shaped convex portion 51, no vent hole is formed in the bonding area formed in the non-recording area 19 on the outer peripheral side.

As described above, the information recording medium of the present invention is preferably manufactured using an ultrasonic fusion machine and a thermal fusion machine (impulse sealing may also be used). The films can also be joined by only one of the thermal fusion method and the ultrasonic fusion method.

However, in the case of bonding by a heat fusion method, the resin film may shrink or deform due to heat, which may cause the resin substrate to warp, so consideration must be given to the bonding conditions. - On the other hand, as an alternative fusion bonding method to the thermal fusion method, there is an ultrasonic fusion bonding method that has fewer problems with thermal shrinkage. A large amount of energy is required, which may vibrate the resin film and damage the recording layer on the surface of the resin substrate, so consideration must be given to bonding conditions.

Note that the above description describes preferred embodiments of the information recording medium of the present invention, and the present invention is not limited to the above configuration. It may be provided only on the opposing surfaces, or may be provided on both sides.

Further, as described above, the entire surface of the micro-irregularities may have micro-irregularities, but the effect of the present invention can be obtained if at least the surface of the protrusions has further micro-irregularities. . Furthermore, the shape of the island-like joints may be one point, the shapes of the island-like joints may not be the same, and the intervals between the island-like joints may not be all the same, but may be changed as appropriate. In addition, a ring shape in which the inner circumferential side and/or outer circumferential side are discontinuously joined does not have the configuration shown in FIGS. It may be formed to have only a small number of non-bonded parts.

The inner circumferential side and the outer circumferential side may be joined first, or may be performed simultaneously.

The joint between the resin substrate and the resin film becomes a non-recording area. However, the recording layer material may be formed all over the resin substrate before bonding from the periphery of the hole to the outer periphery, and the recording layer material may be present in the non-recording area.

A label may be printed on the resin film.

Since any known resin film, recording layer, and resin substrate constituting the information recording medium of the present invention can be used, these will be briefly explained below.

The material of the resin film used in the present invention is not particularly limited as long as it can be processed into irregularities.
It is preferable to use a material that has at least the same main components as the substrate material, and using the same material as the substrate material is
Particularly preferred materials for the resin film include acrylic resin, vinyl chloride resin, polystyrene resin, polyamide resin, polyolefin resin (e.g., polypropylene, polyethylene), polycarbonate, polyester resin, and polyvinylidene chloride. Thermoplastic resins can be mentioned. 0 The double textured resin film used in the present invention is generally subjected to embossing treatment to provide minute but relatively large unevenness, and then the surface is further processed. This can be obtained by roughening the surface by sandblasting and providing finer unevenness in the uneven portion.

The resin 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. Acrylic resin; vinyl chloride resin such as polyvinyl chloride and vinyl chloride copolymer;
Preferred examples include epoxy resins; amorphous polyolefin resins; and synthetic resins such as polycarbonate. Among these, preferred are polymethyl methacrylate, polycarbonate, and epoxy resin in terms of dimensional stability, transparency, and flatness.

The substrate material and the resin film material are preferably manufactured from the same material. For example, it is preferable to bond a polycarbonate film onto a polycarbonate substrate.

A pre-groove layer or a pre-pit layer may be provided on the substrate (or undercoat layer) for the purpose of forming tracking grooves or irregularities representing information such as address signals.

As a material for the pre-groove layer, etc., a mixture of at least one type of hetamine (or oligomer) selected from monoesters, diesters, triesters, and tetraesters of acrylic acid and a photopolymerization initiator can be used.

The pre-groove layer is formed by first coating a mixture of the above acrylic ester and polymerization initiator on a precisely made matrix (stamper), then placing the substrate on top of this coating solution layer. , the substrate and the liquid phase are fixed by curing the liquid layer by irradiating ultraviolet rays through the substrate or the matrix.
Next, by peeling the substrate from the mother mold, a substrate provided with a pregroove layer is obtained. The thickness of the pregroove layer etc. is generally within the range of 0.05 to 1100 IL, preferably within the range of 0.1 to 507 zm. Furthermore, when the substrate material is plastic, pregrooves or prepits may be provided directly on the substrate by injection molding, extrusion molding, or the like.

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

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, Al2O, etc.) and inorganic fluorides (MgF2).

Examples of materials used for the recording layer include Te, Zn, I
n, Sn, Zr, An, Ti, Cu, Ge, Au, Pt
Metals such as; 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, a combination of Dye 1 and a polymer, or a dye and the metal or metalloid listed above can also be used.

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

The recording layer is formed by vapor depositing and sputtering the above materials.

It can be formed directly on the substrate or via an undercoat layer by methods such as ion blasting and coating. The recording layer may be a single layer or a multilayer, but the layer thickness is usually 100 to 5,500 from the viewpoint of optical density required for optical information recording.
It is preferably in the range of 150 to 10,001.

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.

Next, examples of the present invention will be described. However, each of these cases does not limit the present invention.

[Example 1] (1) A disc-shaped polycarbonate substrate having a tracking groove (outer diameter: 120 mm, inner diameter 15 mm, thickness 1.
A groove having a depth of 0.08 μm, a radius of 1.1 pm, and a pitch of 1.6 parts m was provided in a spiral shape within a range of 2 mm in inner diameter to 118 mm in outer diameter by injection molding.

(2) Apply a coating solution with the following composition onto the surface of the substrate having tracking grooves using a spin code method (rotation speed: 700 rpm)
After coating, it was dried at a temperature of 70° C. for 10 minutes to provide a chlorinated polyethylene layer with a dry film thickness of 150 mm.

Coating liquid composition Chlorinated polyethylene 0.3 parts - (C2Ha-F Cjly)n- (V = 1.7, n = 200) n-Butyl acetate 1 part Methyl ethyl ketone 9 parts Cyclohexane 100 parts (3) On the chlorinated polyethylene layer Au, In and Ge
S was co-deposited at a weight ratio of 35%, 40%, and 25%, respectively, to form a recording layer having a layer thickness of 1000 layers. At this time, the heating current flowing through the Au evaporation source was controlled so that the Au concentration was high on the substrate side and decreased as it approached the surface of the recording layer. Note that the Au concentration on the substrate side surface of the formed recording layer was 80% by weight.

(4) Embossed unevenness on both sides (A side: maximum unevenness height 20.OILm, minimum unevenness height 10°0% rh,
Side B: Side A of a polycarbonate film with a maximum unevenness height of 1000 m) was sandblasted to form even finer unevenness. The minimum height of the unevenness on the A side obtained is 1. OILm was formed, and even finer unevenness was formed. This was cut into a piece with a center hole diameter of 35 mm and an outer diameter of 120 mm.

(5) The matte film was stacked concentrically on the surface of the recording layer with side A having the larger surface roughness facing.

(6) At the outer edge of a concentric circle with an assumed diameter of 37 mm on the matte film, place an application horn of an ultrasonic fusion machine (at the tip of the application horn in contact with the film surface, add a tip with a length of 0.
6mm wedge-shaped ridges with a distance of 0 between the tips of the ridges.
．． 8 mm, formed so as to be arranged radially with respect to the center of the application horn), and applied ultrasonic waves while applying pressure to bond the substrate and the matte film in the non-recording area on the inner peripheral side.

(7), At the inner edge of the concentric circle with a diameter of 119 mm that was assumed to be on the resin substrate to which the matte film created in (6) was bonded, there is a heater block (at the tip of the heater block that is in contact with the film surface, the length of the tip is 0). .6mm wedge-shaped protuberances arranged radially with respect to the center of the heater block with a spacing of 0.8mm between the tips of the protuberances) are applied, heated and pressurized, and the outer peripheral side The substrate and the matte film were bonded in the non-recording area to produce an optical disc in which the resin film was bonded to the resin substrate on which the recording layer was formed.

[Example 21 (1) The same substrate as in (1) of Example 1 was prepared.

CH3C104-CH3 1g of cyanine dye represented by the above formula is 1.1,2
．． A dye recording layer coating liquid (?a degree: 1% by weight) was prepared by dissolving it in 100 cc of 2-tetrafluoropropanol.

(3) After applying the coating liquid onto the surface of the substrate having tracking grooves using a spin code method at a rotation speed of 85° rpm, 10 pieces were dried at a temperature of 70°C until the film thickness was 600°.
A R layer was formed.

(4) Next, operations similar to (4) to (7) of Example 1 were performed to produce an optical disc in which a resin film was bonded to a resin substrate on which a recording layer was formed.

[Reference Example 1] An optical disc was manufactured in the same manner as in Example 1 except that the resin film was not bonded.

[Evaluation of information recording media] The optical discs of Examples 1 and 2 and Reference Example 1.

Disc evaluation device i (Nakamichi)
The evaluation was made as follows using a disk evaluation device (ONS).

(1) No difference was observed in sensitivity, C/N, jitter, reading error, substrate warpage, or surface runout depending on whether a resin film was used or not.

(2) The optical disc of Example 1.2 was heated at 60°C and 90%RH.
Store it in a constant temperature and humidity chamber for 10 days, and the resin film will peel off.
We investigated changes in warpage and surface runout of the resin substrate, but found no change from before it was placed in a constant temperature and humidity chamber.

(3) Put the optical disc of Example 1.2 into a vacuum container,
Although the pressure was reduced to 1 torr, there was no swelling of the resin film or warping of the substrate.

In other words, since the optical disc of Example 1.2 uses a resin film with finer irregularities formed on its surface as a protective film, the recording characteristics such as sensitivity and C/N are as good as those without using a protective film. It has the same performance as the example. Furthermore, as shown in (2) and (3) above, it can be seen that it has excellent storage stability.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the information recording medium of the present invention viewed from the side to which the resin film is bonded. FIG. 2 is a sectional view of the information recording medium of the present invention taken along line II in FIG. 1. FIG. 3 is an enlarged cross-sectional view showing the surface shape of the protective resin film of the information recording medium of the present invention and the state of contact with the recording layer. FIGS. 4 and 5 are cross-sectional views for explaining the method for manufacturing an information recording medium of the present invention. lO: Information recording medium 11: Disc-shaped resin substrate 12: Disc-shaped resin film 13.17: Hole 14: Inner circumferential bonding area 15: Outer circumferential bonding area 16: Island-shaped bonding portion 18: Inner Circumferential non-recording area 19: Outer circumferential non-recording area 20: Recording layer 21: Vent hole 22: Space 40: Ultrasonic fusion machine 41: Application horn 42: Holder is jig 43. 51: Ring-shaped convex Part 44: Protuberance 45: Ultrasonic oscillator 46: Converter: Heat fusion machine 52: Heater block: Power supply line

Claims (1)

[Claims] 1. A hole is provided in the center, and a recording layer is provided in an area other than the inner non-recording area and the outer non-recording area set outside the periphery of the hole and inside the outer periphery, respectively. The disk-shaped resin substrate has a hole in the center on the surface thereof facing the recording layer, has minute irregularities on at least the surface facing the recording layer, and has at least the surface of the convex portions of the irregularities. An information recording medium characterized in that a flexible disk-shaped resin film having minute irregularities is bonded to an inner non-recording area and an outer non-recording area of the resin substrate.