JPH09223335A - Optical recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the double refraction of a transparent substrate due to the thermal strain generated in laser beam cutting in a production stage by providing an optical card with a deformation buffer part consisting of a groove-shaped space between the outer periphery end and optical recording region of this card. SOLUTION: The optical card 1 is constituted by laminating and forming an optical recording layer, an adhesive layer and a protective layer in this order on the transparent substrate which consists of, for example, a polycarbonate resin and is the incident surface for a laser beam. In production of the optical card 1, a laminated layer forming stage, etc., are ended with a work sizes larger than the card size and the card is formed to have a prescribed size by cutting with the laser beam in the final stage. The deformation buffer layer 3 is formed on the transparent substrate between the outer periphery end and optical recording region 2 of the optical card 1. The deformation buffer part 3 is formed in a groove shape having, for example, a rectangular shape in section and is so set that the depth is 0.25 to 0.51mm in correspondence to 0.76mm thickness of the card and that the width is 0.5 to 2.0mm and that this part exists in the position apart by >=0.2mm inward from the outer periphery end of the card.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium for optically recording / reproducing information and its manufacturing method.

[0002]

2. Description of the Related Art As means for efficiently handling a wide variety of information, many information recording media such as optical disks, optical cards, optical tapes, etc. for optically recording or reproducing information and information recording / reproducing devices have been proposed. Information is recorded on the information recording medium by the change of the refractive index due to the heat of the laser beam and the change of the surface shape such as the formation of pits (holes), and the change of the polarization plane by the magneto-optical effect. A characteristic of the information recording medium is that it has a high recording density and can record and reproduce in a non-contact manner, so that it has a long life.

Recently, a card type optical information recording medium (hereinafter referred to as an optical card), which is excellent in portability and has a large capacity as compared with its size, has been actively researched and developed and proposed. There is.

An optical card will be described below as an information recording medium for optically recording and reproducing information. In the optical card, a track for tracking and a pre-format pattern called a pit string of pre-format information such as a sector number or a track number are formed in advance in a concave or convex shape on the information recording surface side of the substrate. The optical card is configured by forming an optical recording material on the substrate on which the uneven preformat is formed and laminating a back substrate with an adhesive.

In the manufacturing process of an optical card, a work size larger than the card size (hereinafter referred to as a work size) is passed through each process, and a work size in which the above layers are stacked is cut into a card size in the final process. Become. As a method of cutting into a card shape, a cutting method using a card-shaped hollow blade by pressing and a method of melting and cutting the outer peripheral portion of the card with a laser are known.

In the card cutting process, when a card made of a hard and fragile substrate material such as acrylic resin is cut by a hollow blade, a crack is generated at the cut end, so that cutting by the hollow blade is impossible. Even when the card of other resin substrate is cut with a hollow blade, the sharpness of the blade is reduced when cutting several thousand cards, the unevenness of the cut surface of the card becomes large, and the cut portion of the card has cracks. . Therefore, the cutting of the card is generally performed by a laser cutting method.

[0007]

However, the laser cutting method is a method of melting and cutting the card by irradiating the card cutting position with laser light and converting it into heat. To expand and contract, leaving optical distortion on the substrate after cutting. Especially for optical cards,
Since the shape is rectangular, optical distortion occurs in an X shape inside the card starting from the corner of the rectangle.

The present invention has been made to solve the above problems, and provides an optical recording medium that does not cause optical distortion that occurs in a laser cutting process in manufacturing an optical recording medium. With the goal.

[0009]

That is, according to the present invention, an optical recording medium obtained by cutting an optical recording medium having a size larger than a prescribed size into a prescribed size by a laser beam is deformed by forming voids in at least a part of its outer peripheral portion. An optical recording medium having a buffer portion.

Further, according to the present invention, the outer side of the deformation buffering portion of the optical recording medium having a size larger than the regulation in which the deformation buffering portion formed of a void is provided in at least a part of the outer peripheral portion is cut by laser light. A method for manufacturing an optical recording medium, characterized in that a deformation buffering portion composed of a void is provided in at least a part of an outer peripheral portion, which is characterized in that a prescribed size is set.

The optical recording medium of the present invention is preferably an optical card. An optical recording medium of the present invention, for example, an optical card will be described. It is characterized in that a deformation buffer portion is formed on the outer peripheral portion of the card.

It is most effective that the deformation buffering portion is a void as a buffering effect for the deformation in the cutting process by the laser light. Further, in order to increase the strength of the outer peripheral portion of the card, a material having a buffering effect such as a porous material may be filled in the void.

The deformation buffering portion of the optical card of the present invention is a step of cutting a card work size larger than the standard in the manufacturing process of the optical card into a specified card size, and the resin as the substrate material is melted and cut by the laser light. It acts as a buffer band to prevent the expansion and contraction when it is solidified from being transmitted to the inside of the card.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an embodiment of an optical card as an example of the optical recording medium of the present invention. The optical card 1 of the present invention is provided with a deformation buffer portion 3 formed in the vicinity of the outer peripheral portion of the card, and the optical recording area 2 is arranged inside thereof.

FIG. 2 is a sectional view taken along the line AA 'of FIG.
In FIG. 2, the cross section of the optical card has a transparent substrate 4, an optical recording layer 5, an adhesive layer 6, and a protective layer 7 stacked in this order from the incident surface of the laser light 9. On the optical recording layer 5 side of the transparent substrate 4, a pre-format pattern 8 including tracking grooves and pre-pits and a deformation buffer portion 3 are formed.

The position on the card surface where the deformation buffering portion 3 of the present invention is provided is between the end of the card and the optical recording area.
In consideration of burrs on the edge of the card, it is preferably located at least 0.2 mm inside the edge of the card and outside the optical recording area. The surface shape may be provided on the entire circumference of the outer peripheral portion of the card as shown in FIG. 1, but a sufficient effect can be obtained especially only at a corner portion where a large optical distortion remains.

If the thickness of the deformation buffering portion (thickness in the thickness direction of the card) is too thick, the card will not plastically deform to return to its original shape when the card is bent, and if it is too thin, the effect of buffering the deformation cannot be obtained. The thickness of the deformation buffering portion is preferably 1/10 to 3/4, preferably 1/3 to 2 / of the card thickness.
3 range, that is, in the case of an optical card, the thickness is 0.76 mm, so 0.08 to 0.6 mm, preferably 0.25 to
A range of 0.51 is desirable.

If the width of the deformation buffering portion is narrow, the deformation buffering effect cannot be obtained, and if it is wide, it enters the optical recording area. Therefore, the preferable width is 0.1 mm to 5 mm, more preferably 0.5 to 5. The range is 2.0 mm.

The cross-sectional shape of the deformation buffering portion is circular,
You can freely choose from ellipses, trapezoids, triangles, polygons, and rectangles. The deformation buffering portion may be provided only on the transparent substrate, but it is more effective if it is also provided on the protective layer as shown in FIG.

As the porous material which can be filled in the voids of the above-mentioned deformation buffering portion, any porous material can be used as long as it has an effect of buffering the deformation due to laser cutting. For example, silver,
Fine particles of a metal such as gold or palladium or an alloy thereof, or spherical fine particles of a polymer such as polyethylene or nylon can be used. The diameter of the fine particles is 0.1 to 100 μm.
m, preferably 10 to 30 μm.

The transparent substrate 4 used in the present invention is
Any resin can be used as long as it is a resin material having good transparency and moldability that can be used as a substrate for an optical card.
Examples thereof include epoxy resin, acrylic resin, allyl resin, polycarbonate resin, polystyrene resin, polyester resin, copolymers and mixtures thereof.

As a method for forming a concavo-convex preformat having good signal transferability, a compression molding method in which a stamper having concavities and convexities previously formed and a thermoplastic resin are hot pressed, a stamper type and a mirror surface type are interposed via a spacer. A pair of cells into which a high-molecular monomer or prepolymer is injected, and cured by radiation such as heat or light to form a resin substrate. Casting method, pellet or flake thermoplastic resin is melted at high speed. A known method such as an injection molding method of filling the inside of a mold in which a stamper is placed, or an extrusion molding method of pressing the molten resin with a pair of rolls including a roll having a stamper and a mirror surface roll to form a sheet Can be used.

As the stamper for cast molding, a chromium film is formed on a glass plate by a sputtering method, and the chromium film is patterned by a photolithography technique to form a required preformat pattern or a metal using a photolithography technique. Conventionally known patterned materials can be used. Other stampers are the same as those for cast molding, or those with a preformatted pattern formed on a photoresist on a glass substrate using photolithography technology are used as a master, and a conductive film and an electroformed film are sequentially formed on the master. A method of forming and peeling to form a stamper, or using the above-mentioned master, after making a replica with 2P resin, a conductive film is formed by sputtering, and a metal film is formed on the conductive film by electroforming. It can be manufactured by a known method of peeling and manufacturing a stamper.

As the material of the stamper for cast molding, glass or metal such as super steel alloy, chrome steel, cast iron, steel for mold can be used. As a material of the stamper of another molding method, a metal that can be electroformed and has good durability due to temperature and pressure during molding is used. As such a material, nickel and copper are preferable. The conductive film is also made of a material that has good durability against temperature and pressure during molding and has good adhesion to the electroformed film. It is preferable to use the same material as the electroformed material in consideration of the adhesion. The thickness of the stamper is set to 0.1 to 0.5 mm in consideration of strength.

The void, which is a deformation buffer portion formed in the optical card, is a groove of the above-described shape provided in the substrate or the protective layer. As a method of forming the groove, a convex portion is formed on the stamper. There are a method of forming and preforming at the same time when forming the preformat, and a method of forming the deformation buffering portion of the transparent substrate or the protective layer by cutting with a precision grinding device.

A material that can withstand the temperature and pressure applied during the molding of the substrate is used for the convex portion, and metals such as iron, nickel and copper, or ceramics such as alumina, zirconia and magnesia are suitable.

Examples of the method of forming the convex portion include a method of welding to the stamper with a laser or an electron beam when the convex portion is a metal, or a method of adhering the above material with an adhesive.

Further, in the recording layer, when the wavelength of the reproducing energy beam is 650 nm or more, particularly 700 to 900 nm, the difference between the reflectance in the pit which is the recording portion and that in the unrecorded portion is large. Is preferred. Further, it is preferable that the energy required for changing the reflectance due to the irradiation of the energy beam for recording is small.
Further, it is preferable that the reflectance of the recorded portion and the unrecorded portion hardly change due to the reproducing energy beam.

For example, Te, Sb, Mo, Ge, V, S
oxides such as n, Ge-Sn-Te, In-Sn-Te,
Compounds such as Te-Sn and TeOx-Ge undergo a phase transition upon irradiation with an energy beam to change the reflectance. Also, the composite or the _{Te-CH 4, Te-CS} 2, Te- _{styrene, Sn-SO 2, GeS-} Sn, SnS-S metal and an organic compound such as an inorganic sulfides, SiO
A multilayer film such as ₂ / Ti / SiO ₂ / Al can also be used. Further, it is also possible to use a material in which metal particles such as silver are dispersed in a thermoplastic resin such as nitrocellulose, polystyrene or polyethylene, or a material in which metal particles are agglomerated on the surface of such a thermoplastic resin. In addition, chalcogen or chromogenic MoO ₃ —Cu, MoO ₃ —S
n-Cu or the like is also used, and in some cases, a multilayer body of a foam-forming organic thin film and a metal thin film can also be used.

An organic thin film whose optical properties can be changed by an energy beam can also be used, and examples thereof include anthraquinone derivatives (particularly those having an indathrene skeleton), dioxazine compounds and their derivatives, triphenodithiazine compounds, phenanthrene derivatives. , Cyanine compounds, merocyanine compounds, pyrylium-based compounds, xanthene-based compounds, triphenylmethane-based compounds, croconium-based dyes, dyes such as crocones, and the like. It is preferred for the invention.

Next, the transparent substrate on which the recording layer has been formed is laminated with the protective layer 7 via an adhesive depending on the mode of use.

In the present invention, the adhesive layer 6 is a conventionally known adhesive, for example, vinyl acetate, acrylic acid ester, vinyl chloride, ethylene, acrylic acid, acrylamide polymer or copolymer of vinyl monomer, polyamide, Thermoplastic adhesive such as polyester and epoxy, amino resin (urea resin, melanin resin), phenol resin, epoxy resin, urethane resin, adhesive such as thermosetting vinyl resin, natural rubber, nitrile rubber, chloro rubber, silicone rubber A rubber adhesive or the like is used. In particular, the hot melt type is a dry process and is preferable in consideration of mass production and continuous production.

The protective layer needs to be transparent in the case of a transmissive reading system, and the requirement for birefringence is the same as that for the substrate, and its material is limited by itself. In the case of a reflective reading method, the protective layer may be opaque, and its material can be selected from a wide range. The protective layer is laminated on the recording layer directly in optical contact with the recording layer.

[0034]

The present invention will be described more specifically with reference to the following examples.

Example 1 A stamper was produced as follows.

340 × 340 mm with mirror surface, thickness 1
Photoresist (product name: AZ
-1370; Hoechst Japan Co., Ltd.) thickness 3000Å
Was applied with a spinner and prebaked at 90 ° C. for 30 minutes.

Next, using a laser exposure device (trade name: mirror projection aligner MPA-1500; manufactured by Canon Inc.), a preformat pattern of an optical card of 54.0 × 85.6 mm was exposed to light and a developing solution (commercial product) Name: Az312MIF; manufactured by Hoechst Japan Co., Ltd.) to develop a glass master having a preformat pattern for an optical card.

A 2000 Å-thick nickel film was formed on this master by a sputtering apparatus to form a conductive film for electroforming. Next, a thickness of 200 is formed on the conductive film by electroforming.
A μm nickel film was formed. The electroforming liquid used here had the following composition.

[0039] sulfamyl, nickel tetrahydrate _{[Ni (NH 2 SO 3) 2} · 4H 2 O ] 500 g / l boric acid [H ₃ BO _3] 35~38g bit inhibitor 2.5 ml / 1

Next, the conductive film and the metal film are integrally peeled from the glass master at the same time, the photoresist adhering to the surface is removed, and the preformat pattern 3 is formed.
A stamper having a size of 00 × 300 mm was obtained. Further, in order to form a convex portion corresponding to the void which is the deformation buffering portion, nickel having a shape shown in FIG. 1 (a width of 1 mm and a height of 0.2 mm at a position 3 mm from the end of the card) is used as a YAG laser (JK701; Welded by Lumonix).

This is 200 × 200 with a predetermined dimensional accuracy.
A stamper was obtained by cutting with a YAG laser (JK701; manufactured by Lumonix) to a size of mm.

Further, a member for screwing to the forming roll is a YAG laser (JK701; manufactured by Lumonix).
I welded it to the stamper. This stamper was fixed to the roll with screws to form a forming roll.

An optical card substrate was extruded from a polycarbonate resin by an extrusion molding machine under the following conditions using the roll with a stamper and the mirror surface roll configured as described above.

(Extrusion molding conditions) Extruder temperature 280 ° C. Die temperature 300 ° C. Forming roll temperature 150 ° C. Forming roll speed 4 m / min Forming roll pressure 8 kg / cm ² As a result, a preformat pattern for optical recording on the substrate Thus, the deformation buffer portion could be manufactured with high precision.

On the obtained substrate of this example, a polymethine organic dye having a thickness of about 900Å was formed as an optical recording material by a spin coater. Next, a vinyl chloride protective substrate having a thickness of 0.3 mm was bonded by pressure bonding with a heat roller via an ethylene vinyl acetate copolymer-based adhesive so as to be in contact with the optical recording material.

As the vinyl chloride protective substrate used for the protective layer, the one having the same shape as that of the transparent substrate, which is a deformation buffering portion, (having a height of 0.15 mm) was machined. Next, the Worth size was cut into a card size with a carbon dioxide laser to prepare an optical card.

Example 2 An optical card substrate was manufactured by the same method as in Example 1. However, the void which is the deformation buffering portion was formed into the shape shown in FIG. 3 (a width of 1 mm, a height of 0.2 mm, and a length of 10 mm at the position 3 mm from the card end).

On the obtained substrate of this example, a polymethine organic dye having a thickness of about 900Å was formed as an optical recording material by a spin coater. Next, a vinyl chloride protective substrate having a thickness of 0.3 mm was bonded by pressure bonding with a heat roller via an ethylene vinyl acetate copolymer-based adhesive so as to be in contact with the optical recording material. Next, the Worth size was cut into a card size with a carbon dioxide laser to prepare an optical card.

Comparative Example 1 An optical card substrate was produced in the same manner as in Example 1. However, the deformation buffer portion was not formed. On the obtained substrate, a polymethine organic dye having a thickness of about 900Å was formed as an optical recording material by a spin coater. Next, thickness 0.3m
The vinyl chloride protective substrate of m was brought into contact with the above optical recording material, and was bonded by pressure bonding with a heat roller via an ethylene vinyl acetate copolymer adhesive. Next, the Worth size was cut into a card size with a carbon dioxide laser to prepare an optical card.

Table 1 shows the results of measuring the birefringence (retardation double pass unit nm measuring device: ADR60XY manufactured by Oak Manufacturing Co., Ltd.) of the transparent substrate of the optical card thus manufactured.

[0051]

[Table 1]

As shown in Table 1, the birefringence at the lower left and right corners of the lower portion of the card of Comparative Example 1 was 20n due to the increase in the birefringence at the laser cutting, in contrast to the birefringence at the card center of gravity position.
Although the value exceeds m, it is 12 in the first and second embodiments.
Since it was less than or equal to nm, the increase in birefringence due to laser cutting could be suppressed to a small level.

[0053]

As described above, the optical recording medium of the present invention can suppress the birefringence of the transparent substrate of the card, which is caused by laser cutting which is a manufacturing process of the card, to be sufficiently small, especially in the optical card. . Further, according to the method for producing an optical recording medium of the present invention, particularly in an optical card, it is possible to obtain an optical recording medium in which the birefringence of the transparent substrate of the card generated by laser cutting is sufficiently suppressed.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an optical card as an example of an optical recording medium of the present invention.

2 is an embodiment of the optical card of the present invention, A of FIG.
It is a sectional view taken on line -A '.

FIG. 3 is a plan view showing another embodiment of the optical card of the present invention.

[Explanation of symbols]

 1 Optical Card 2 Optical Recording Area 3 Deformation Buffer Section 4 Transparent Substrate 5 Optical Recording Layer 6 Adhesive Layer 7 Protective Layer 8 Preformat Pattern 9 Laser Light

Claims (4)

[Claims] 1. An optical recording medium obtained by cutting an optical recording medium of a size larger than a prescribed size to a prescribed size with a laser beam, wherein a deformation buffer portion consisting of a void is provided in at least a part of an outer peripheral portion. And an optical recording medium. 2. The optical recording medium according to claim 1, wherein the void is filled with a porous material. 3. The optical recording medium according to claim 1, wherein the optical recording medium is an optical card. 4. A laser light is used to cut the outside of the deformation buffering portion of an optical recording medium having a size larger than the regulation in which at least a part of the outer peripheral portion is provided with a deformation buffering portion, and the deformation buffering portion is made into a prescribed size. The method of manufacturing an optical recording medium according to claim 1, wherein