JP2008004174A - Metal mold for optical information recording medium and optical information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal mold for an optical information recording medium for molding a substrate of the optical information recording medium whose appearance defect is not generated. <P>SOLUTION: The metal mold 10 for the optical information recording medium is provided with a surface side mirror part 11, a recording side mirror part 12 to which a stamper 13 is to be attached, a cavity ring 14 vertically slid by a cavity ring spring 15 and an abutting ring 16. Since the surface side mirror part 11 has a projecting step difference part 111 at its outer peripheral part opposed to the cavity ring 14, a recessed step difference part 21 with a burr 22 is formed on the outermost periphery of the disk-like substrate 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical information recording medium mold and the like, and more particularly to an optical information recording medium mold for molding a substrate of an optical information recording medium.

With the spread of personal computers and DVD recorders, as recordable optical information recording media, for example, CD-R and DVD-R that can be written only once, CD-RW, DVD-RW, and DVD that can be recorded repeatedly. -Optical disks such as RAM are widely used.
Some of these optical discs are provided with a printable layer that can be printed using a home inkjet printer. As a method for forming the printing layer, a method of forming an ultraviolet curable resin that becomes a printing layer on the substrate surface on the substrate surface by using a spin coating method is generally used.
Also, the shape of the substrate has been devised in various ways. For example, as shown in Patent Document 1, a stepped portion is used as identification information by using a substrate having a stepped portion that is one step lower on the outer peripheral portion. A method to do this has been proposed.

JP-A-8-249802

By the way, since the substrate of the optical information recording medium is usually formed by injection molding, burrs are generated in the gap between the cavity which is the outer peripheral end of the substrate and the incident side mirror surface portion of the mold. This will be described with reference to the drawings.
FIG. 4 is a schematic cross-sectional view for explaining the outer peripheral structure of a conventional injection mold. FIG. 4A shows a mold 30 when a transparent substrate of an optical information recording medium is formed by injection molding. The mold 30 slides up and down by an incident-side mirror surface portion 31 that forms the incident-side surface of the transparent substrate, a recording-side mirror surface portion 32 to which a stamper 33 is attached, and a cavity spring 35 facing the incident-side mirror surface portion 31. A cab ring 34 and an abutment ring 36 are included. A cavity 37 through which the molten resin is injected is formed by the incident side mirror surface portion 31, the recording side mirror surface portion 32, and the cab ring 34.

As shown in FIG. 4A, a gap (portion surrounded by a circle in the figure) is generated between the cavity ring 34 that forms the outer peripheral end portion of the cavity 37 and the incident side mirror surface portion 31. Therefore, when cooling the injected molten resin into the cavity 37, as shown in FIG. 4 (b), the substrate S ₀ which is molded, the surface on which the fine pattern is formed by a stamper 33 (recording surface) burr B ₁ is generated in the outer edge of the opposite side surface (incident surface).

When the incident surface side of the molded substrate S ₀ has burrs B ₁ as shown in FIG. 4 (b), as shown in FIG. 4 (c), for example, used in high-density medium, such as a movie for a DVD substrate When the ultraviolet curable resin layer A is formed on the incident surface side of S ₀ in order to prevent the adhesion of dust or scratches, the resin reservoir A ₁ protrudes from the outer peripheral end surface of the medium, resulting in poor appearance.
Here, FIG. 5 is a diagram for explaining the appearance defect of the medium. As shown in FIG. 5, when the surface of the optical information recording medium to form an ultraviolet-curable resin layer A, the poor appearance caused by A ₁ resin reservoir protruding on the outer circumferential edge surface of the medium.

That is, when the ultraviolet curable resin is applied to the incident surface side of the substrate S ₀ by the spin coating method, the burr B ₁ becomes an obstacle and the ultraviolet curable resin does not spread uniformly. Furthermore, when the excess resin is shaken off, as shown in FIG. 4C, the ultraviolet curable resin remains in the burr B ₁ portion (resin pool A ₁ ) due to surface tension or the like, and as a result, the substrate S ₀ Appearance defects occur at the outer peripheral edge. Such poor appearance, using the substrate S ₀ as a dummy substrate, produces an ultraviolet curable resin to form a printing layer on the surface of the dummy substrate in the same manner may be applied by spin coating.

For example, a mold as shown in FIG. 6A has been reported as a method of reducing burrs generated at the outer peripheral edge of a substrate molded by such injection molding.
FIG. 6 is a schematic cross-sectional view for explaining the outer peripheral structure of another conventional injection mold. A mold 40 shown in FIG. 6A includes an incident-side mirror surface portion 41, a recording-side mirror surface portion 42, a stamper 43, a cab ring 44, a cavitation spring 45, and an abutment ring 46, and a molten resin is injected. A cavity 47 is formed.

As shown in FIG. 6A, the cavity 44 of the mold 40 is provided with a step portion at a part on the outermost peripheral side of the cavity 47 (a portion surrounded by a circle in the figure). However, upon cooling the injected molten resin into the cavity 47, a gap between an incident-side mirror surface portion 41 and the cavity ring 44 is present, as shown in FIG. 6 (b), the incidence of substrate S ₀ which is formed burr B ₂ is generated in the outer edge of the side. When an ultraviolet curable resin is applied to such a substrate S ₀ , as shown in FIG. 6C, the ultraviolet curable resin remains in the burr B ₂ portion (resin reservoir A ₂ ), and the appearance is the same as in FIG. Defects occur.

  The burrs generated on such a substrate can be cut and reduced by, for example, a mechanical process. However, there are further problems such as generation of scraps and an increase in the cutting process. .

The present invention has been made to solve these problems.
That is, an object of the present invention is to provide a mold for an optical information recording medium for forming a substrate of an optical information recording medium that does not cause an appearance defect.
Another object of the present invention is to provide an optical information recording medium with improved appearance defects.

  Thus, according to the present invention, there is provided an optical information recording medium mold for forming a substrate of an optical information recording medium, the recording side mirror surface portion to which the stamper is attached, the recording side mirror surface portion facing the recording side mirror surface, A surface side mirror surface part that forms a cavity in which a molten resin is sealed between and a cavity ring that forms an outer periphery of the cavity, and the surface side mirror surface part is an outer periphery part that faces the cavity side cavity ring There is provided a mold for an optical information recording medium characterized by having a convex step portion.

By using such a mold for optical recording media, it is possible to adjust the burr generation part to a part different from the surface of the substrate.
Here, the step portion formed in the surface side mirror surface portion used for the optical recording medium mold is formed such that the inner peripheral surface of the step portion has a tapered shape having a predetermined angle from the surface of the surface side mirror surface portion. It is preferable.

Next, according to the present invention, there is provided an optical information recording medium including a disc-shaped substrate having at least one information recording layer, wherein the thickness of the substrate is formed on the outer peripheral end of the surface opposite to the information recording layer of the substrate. An optical information recording medium is provided in which a step portion thinner than the above is provided.
In the case where an ultraviolet curable resin is applied by spin coating to form an image forming layer or a hard coat layer on the substrate surface by providing a stepped portion on the outer peripheral side of the substrate of the optical information recording medium, for example, It is possible to form a uniform layer without coating unevenness without being affected by burrs generated when the film is formed.

Here, the optical information recording medium can be provided with an image forming layer formed on the surface of the substrate.
It is also possible to have a protective layer on the light incident surface side of the substrate.

  According to the present invention, it is possible to mold a substrate of an optical information recording medium that does not cause an appearance defect.

  The best mode for carrying out the present invention (hereinafter, an embodiment of the present invention) will be described in detail below. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention. The drawings used are for explaining the present embodiment and do not represent the actual size.

FIG. 1 is a diagram for explaining an optical information recording medium mold to which the present embodiment is applied.
FIG. 1A is a view for explaining the outer peripheral structure of an optical information recording medium mold 10, and FIG. 1B is an outermost end portion of a substrate molded with the optical information recording medium mold 10. FIG. 1C shows the outermost end of the ultraviolet curable resin layer formed on the substrate surface.

  The optical information recording medium mold 10 shown in FIG. 1A has a surface side mirror surface portion 11 that forms the surface of a substrate such as a transparent substrate or a dummy substrate made of a thermoplastic resin, and a fine pattern of pits or grooves in advance. The recording side mirror surface portion 12 to which the provided stamper 13 is attached, a cab ring 14 that slides up and down by a cab ring spring 15 facing the surface side mirror surface portion 11, and an abutting ring 16 are configured. A cavity 17 through which molten resin is injected is formed by the front-side mirror surface portion 11, the recording-side mirror surface portion 12, and the cab ring 14.

  As shown in FIG. 1 (a), the surface side mirror surface portion 11 of the optical information recording medium mold 10 to which the present embodiment is applied has a convex shape on the outer peripheral portion facing the cavity ring 14 on the cavity 17 side. The step portion 111 is formed. When the molten resin injected into the cavity 17 is cooled by providing the stepped portion 111, burrs are formed on the side of the molded substrate 20 in contact with the surface side mirror surface portion 11 as shown in FIG. Accordingly, the burrs 22 remain on the stepped portion 21 on the outermost periphery of the substrate 20.

  For this reason, when an ultraviolet curable resin is applied to the surface of such a substrate 20 by a spin coating method, it can be applied uniformly without being affected by burrs. As a result, as shown in FIG. 1C, the ultraviolet curable resin layer 23 formed on the surface of the substrate 20 can maintain a uniform appearance without causing resin accumulation at the outermost peripheral end portion of the substrate 20. it can.

Next, FIG. 2 is a diagram for explaining the convex step portion of the surface side mirror surface portion 11 used in the optical information recording medium mold to which the present embodiment is applied.
As shown in FIG. 2A, the convex stepped portion 111 of the surface side mirror surface portion 11 has a height H ₁ and is provided on the outer peripheral portion of the surface side mirror surface portion 11 with a predetermined width L _1. . The height H ₁ is not particularly limited, but considering that the thickness of the substrate of the optical information recording medium is about 0.6 mm, H ₁ is usually in the range of 0.05 mm to 0.2 mm, preferably Is in the range of 0.05 mm to 0.1 mm. The width L ₁ is not particularly limited, but usually L ₁ is in the range of 0.1 mm to 0.25 mm, and preferably in the range of 0.15 mm to 0.2 mm.

FIG. 2B is a diagram for explaining a tapered step portion 112 having a predetermined angle θ provided on the surface side mirror surface portion 11. The step portion 112 has a height H ₂ and has a predetermined width L ₂ and is provided on the outer peripheral portion of the surface side mirror surface portion 11. The height _{H 2} is generally in the range of 0.05 mm to 0.2 mm, preferably in the range of 0.05 mm to 0.1 mm. The width _{L 2} is typically, _{L 1} is in the range of 0.15 mm to 0.3 mm, preferably in the range of 0.15Mm～0.2Mm. Further, the angle θ is usually in the range of 15 degrees to 75 degrees, and preferably in the range of 30 degrees to 60 degrees.

Next, an optical information recording medium to which this embodiment is applied will be described.
FIG. 3 is a diagram for explaining the structure of an optical information recording medium to which the present embodiment is applied. Here, a write-once type optical information recording medium (DVD-R) formed by bonding a substrate having a dye film and a dummy substrate will be described as an example. The optical information recording medium is not limited to the write-once optical information recording medium, but is a rewritable optical information recording medium (DVD-RW, DVD + RW, DVD-RAM) and a read-only optical information recording medium (DVD-ROM). ).
Further, the present invention can be applied to both a substrate incident type medium and a film surface incident type medium.

  As shown in FIG. 3A, an optical information recording medium M includes a substrate 1 provided on the light incident surface side, an information recording layer 3 for recording or reading information by light, and a substrate sandwiching the information recording layer 3 1 and a dummy substrate 2 to be bonded together.

Next, the material of each layer constituting the optical information recording medium 100 to which this embodiment is applied will be described.
The substrate 1 is made of a light transmissive material. Examples of the light transmissive material include synthetic resins such as polycarbonate resin, polymethyl methacrylate resin, epoxy resin, and ABS resin.
The dummy substrate 2 is preferably formed using the same material as the substrate 1.

The information recording layer 3 usually has a dye layer and a reflective layer. The information recording layer 3 may include a plurality of dye layers, a reflective layer, and other layers as necessary. In addition, when two dye layers are included, a reverse laminated structure or a normal laminated structure may be used.
The dye layer can be formed by applying a dye solution prepared by dissolving an organic dye compound in a predetermined solvent onto a pregroove formed in the information recording area of the substrate 1 by a spin coating method or the like. . Examples of organic dye compounds include cyanine dyes, squarylium dyes, croconium dyes, azurenium dyes, triarylamine dyes, anthraquinone dyes, metal-containing azo dyes, dithiol metal complex dyes, indoaniline metal complexes. And system dyes, phthalocyanine dyes, naphthalocyanine dyes, and the like.

  The reflective layer can be formed of a metal such as Au, Ag, Cu, Ni, Al, Pt or an alloy material thereof by a vacuum deposition method, a sputtering method, an ion plating method, or the like.

  The substrate 1 and the dummy substrate 2 are bonded together through an adhesive layer. The adhesive layer can be formed by applying an adhesive on the reflective layer by a method such as spin coating, gravure coating, spray coating, or roll coating. Examples of the adhesive include an ultraviolet curable acrylic resin, an ultraviolet curable epoxy resin, an ultraviolet curable adhesive, an epoxy adhesive, a silicone resin, a silicone adhesive, and a hot melt adhesive.

  Note that an image forming layer is provided on the surface of the dummy substrate 2 as necessary. In this case, an image forming layer is usually formed by applying an aqueous coating solution containing an ultraviolet curable resin on the dummy substrate 2 and then irradiating it with ultraviolet rays to cure. Examples of the ultraviolet curable resin include acrylate resins such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate.

Next, FIG. 3B is a diagram for explaining the outermost peripheral end portion of the substrate 1.
As shown in FIG. 3B, a stepped portion 4 formed so that the thickness of the substrate 1 decreases is provided on the outermost peripheral portion of the substrate 1. Moreover, the burr | flash 5 has arisen in the level | step-difference part 4 of the outermost periphery of the board | substrate 1 normally on the surface by the side of the light-incidence surface of the board | substrate 1 which does not arise by the metal mold | die used by injection molding.
By making the shape of the outermost peripheral portion of the substrate 1 in this way, it is possible to uniformly apply the UV curable resin to the surface of the substrate 1 by spin coating, and the UV curable resin is applied to the outermost periphery. It can prevent dripping.

  In the present embodiment, the shape of the outermost peripheral end of the surface of the dummy substrate 2 opposite to the information recording layer 3 is the same as the shape of the outermost peripheral end of the substrate 1 as shown in FIG. A step portion can be provided on the surface. In this case, it is possible to form an image forming layer on which the appearance defect is remarkably improved on the surface of the dummy substrate 2.

That is, conventionally, due to burrs generated on the substrate surface on the incident side and the surface of the dummy substrate at the time of injection molding or the like, the decrease in non-uniform dripping of the UV curable resin applied to these surfaces is greatly reduced.
The optical information recording medium M in which such non-uniform UV curable resin sag is reduced can be used stably without being decentered even at high speed rotation.

Hereinafter, the present embodiment will be described more specifically based on examples. Note that this embodiment is not limited to the examples.
(Example 1)
As described below, an optical information recording medium having a structure in which a transparent substrate having an information recording layer and a dummy substrate were bonded together was prepared, and the appearance of the image forming layer formed on the surface of the dummy substrate was evaluated.
First, as shown in FIG. 1A, an optical information recording medium mold 10 having a surface-side mirror surface portion 11 having a convex stepped portion 111 formed on the outer peripheral portion facing the cavity 14 is used. Then, injection molding was performed with a polycarbonate resin to obtain a disk-shaped transparent substrate having a thickness of 0.6 mm, an outer diameter of 120 mm, an inner diameter (center hole) of 15 mm, and a substrate refractive index of 1.59. As shown in FIG. 1B, a stepped portion was formed at the outer peripheral end of the transparent substrate on the incident surface side, and no burrs were formed on the incident surface side, and burrs were observed at the outermost stepped portion.
A stamper pressing groove having a diameter of 21 mm was formed on the transparent substrate by a stamper, and a pregroove having a track pitch of 0.74 μm, a depth of 160 nm, and a half-value width of 310 nm was formed from the clamp area to the outer periphery.

  Subsequently, a polycarbonate resin dummy substrate was obtained by injection molding using the optical information recording medium mold 10 shown in FIG. The dummy substrate has a thickness of 0.6 mm, an outer diameter of 120 mm, an inner diameter (center hole) of 15 mm, and a substrate refractive index of 1.59. As shown in FIG. 1B, a stepped portion is formed at the outer peripheral end of the dummy substrate in contact with the surface side mirror surface portion, and burrs are generated on the side in contact with the surface side mirror surface portion as in the transparent substrate described above. Not.

  Next, a solution dissolved in a concentration of 1.2% by weight of an azo dye is applied from the vicinity of an information recording area φ36 mm on the recording surface on which the pregroove of the transparent substrate is formed, to form a dye layer. . Next, a reflective layer having a thickness of 100 nm to 200 nm is formed on the dye layer so as to cover φ22 mm to φ119 mm using sputtering of an Ag alloy.

Next, an ultraviolet curable resin is applied as an adhesive on the reflective layer, and the dummy substrate described above is placed on the bonding device so that the center faces each other and an appropriate amount of the ultraviolet curable resin is applied. The solution was dropped and spin-rotated at a high speed to remove excess resin and form an adhesive layer. Subsequently, ultraviolet rays are irradiated in this state to solidify the ultraviolet curable resin, and the transparent substrate having the information recording area and the dummy substrate are bonded together.
Finally, an ultraviolet curable resin was applied to the dummy substrate surface by a spin coating method to form an image forming layer, and an optical information recording medium was prepared.
Next, the appearance of the image forming layer was visually evaluated. The results are shown in Table 1.

(Example 2)
In the optical information recording medium mold 10 shown in FIG. 1 (a), the surface side mirror surface portion 11 is formed with a tapered stepped portion on the outer peripheral portion as shown in FIG. 2 (b). The transparent substrate and the dummy substrate were formed by performing the same operation as in Example 1 instead of the surface-side mirror surface portion. Next, these were bonded together to prepare an optical information recording medium, and the appearance of the image forming layer formed on the surface of the dummy substrate was visually evaluated. The results are shown in Table 1.

(Comparative Example 1)
Using the mold 30 shown in FIG. 4A, the same operation as in Example 1 was performed to form a transparent substrate and a dummy substrate. Next, these were bonded together to prepare an optical information recording medium, and the appearance of the image forming layer formed on the surface of the dummy substrate was visually evaluated. The results are shown in Table 1.

(Comparative Example 2)
Using the mold 40 shown in FIG. 6A, the same operation as in Example 1 was performed to form a transparent substrate and a dummy substrate. Next, these were bonded together to prepare an optical information recording medium, and the appearance of the image forming layer formed on the surface of the dummy substrate was visually evaluated. The results are shown in Table 1.

(Appearance evaluation of optical information recording media)
Table 1 shows the results of visual evaluation of the appearance of the image-forming layer for each of the 100 optical information recording media prepared in Examples 1 and 2 and Comparative Examples 1 and 2, respectively.

  From the results of Table 1, the transparent substrate and the dummy substrate formed by using a mold having a surface side mirror surface portion in which a convex step portion is formed on the outer peripheral portion opposite to the cabling are in contact with the surface side mirror surface portion. There is no burr on the side. For this reason, when an ultraviolet curable resin is applied to the surface of such a dummy substrate by a spin coating method, it can be applied uniformly without being affected by burrs, and an image forming layer in which no appearance defect is observed can be formed. (Examples 1 and 2).

  On the other hand, when the dummy substrate is molded using a mold having a front-side mirror surface portion that does not have a convex step portion on the outer peripheral portion facing the cavity (Comparative Example 1), a part of the cavity on the cavity side The appearance defect occurs when compared with the case of using a mold provided with a step portion (Comparative Example 2). That is, it can be seen that when the ultraviolet curable resin is applied to the surface of the dummy substrate by the spin coating method, a large amount of the ultraviolet curable resin is accumulated in the burr portion, and this portion becomes uneven in coating and appearance failure occurs.

  As described above, as described in the present embodiment, a substrate molded using a mold having a surface-side mirror surface portion in which a convex step portion is formed on the outer peripheral portion opposite to the cavity is formed on the surface-side mirror surface portion. There is no burr on the contact side. For this reason, when an ultraviolet curable resin is applied to the surface of such a substrate by a spin coating method, it can be applied uniformly without being affected by burrs, and a protective layer or an image forming layer in which no appearance defect is observed is formed. Can be formed.

It is a figure explaining the metal mold | die for optical information recording media with which this Embodiment is applied. It is a figure explaining the outer periphery structure of the surface side mirror surface part used with the metal mold | die for optical information recording media with which this Embodiment is applied. It is a figure explaining the structure of the optical information recording medium to which this Embodiment is applied. It is the cross-sectional schematic for demonstrating the outer periphery structure of the conventional injection mold. It is a figure explaining the external appearance defect of a medium. It is the cross-sectional schematic for demonstrating the outer peripheral structure of the other conventional injection mold.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Metal mold | die for optical information recording media, 11 ... Front side mirror surface part, 12 ... Recording side mirror surface part, 13 ... Stamper, 14 ... Cavitation, 17 ... Cavity, 111 ... Step part

Claims (5)

An optical information recording medium mold for forming a substrate of an optical information recording medium,
A recording side mirror surface portion to which a stamper is attached;
A surface-side mirror surface portion that forms a cavity facing the recording-side mirror surface portion and enclosing a molten resin between the recording-side mirror surface portion,
A cavity that forms an outer periphery of the cavity, and
The mold for an optical information recording medium, wherein the surface side mirror surface portion has a convex step portion on an outer peripheral portion facing the cavity on the cavity side.   2. The mold for an optical information recording medium according to claim 1, wherein an inner peripheral surface of the step portion is formed in a taper shape having a predetermined angle from the surface of the surface side mirror surface portion. An optical information recording medium comprising a disk-shaped substrate having at least one information recording layer,
An optical information recording medium, wherein a step portion thinner than the thickness of the substrate is provided at an outer peripheral end of a surface of the substrate opposite to the information recording layer.   2. The optical information recording medium according to claim 1, further comprising an image forming layer formed on the surface of the substrate.   2. The optical information recording medium according to claim 1, further comprising a protective layer on the light incident surface side of the substrate.

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