JPH06195757A - Manufacture of optical recording medium - Google Patents

Abstract

PURPOSE:To improve the productivity and to lower the price by laminating a molten resin on a base sheet, pressing/cooling the laminated body and forming projecting and recessed patterns on the surface of the resin. CONSTITUTION:A resin 5 in the melting state extruded in the form of a sheet from a T-die 2 of an extrusion molding apparatus 1 is formed to be a sheet between a cooling roll 3 and a nip roll 4 arranged immediately after the die 2. At the same time, the resin is pressed by a stamper 6 which is set at the surface of one of the rolls 3, 4 and has projecting and recessed patterns of pits or pregrooves or the like, whereby the patterns are formed on the surface of the resin 5. The obtained resin sheet 5a is wound up by a wind roll 9 via a take roll 8. At this time, the laminated body is cooled to form patterns, and a layer 12 of a light reflecting film is provided on the surface of the sheet 5a where the projecting and recessed patterns are formed, with a protecting coat layer 13 applied onto the layer 12. Further, a label is printed thereon, whereby an optical disc is manufactured in the highly productive method at low costs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical recording medium such as an optical disc (compact disc), a video disc, an optical card and the like. More specifically, it relates to an optical recording medium obtained by applying an extrusion sheet molding technique to form an uneven pattern such as pits and pregrooves on a resin surface, and is particularly inexpensive and formable,
The present invention relates to a method for manufacturing an optical recording medium that improves productivity.

[0002]

2. Description of the Related Art Optical recording has advantages such as non-contact between a recording medium and a read head and high-density information recording as compared with magnetic recording. As this optical recording medium, a read-only type, an additionally writable type, an erasable and rewritable type, etc. are known. In particular, as a read-only optical recording medium, it has already been put to practical use in the form of an optical disc (compact disc), an optical video disc, an optical card, or the like.

In this type of optical recording medium, generally, an information signal (concavo-convex pattern) composed of pits, pregrooves, etc. is formed on the surface of a resin sheet made of plastic, and vapor deposition or A light-reflecting film layer is provided by a method such as sputtering, a protective coat layer is applied on the light-reflecting film layer, and label printing is performed on the protective coat layer.

By the way, as a method of manufacturing a resin sheet in this case, conventionally, an injection molding method in which a concavo-convex pattern such as pits and pregrooves is formed on the resin surface simultaneously with injection molding (injection molding), and a thermoplastic resin is used for the resin sheet. There are a hot pressing method and a 2P method in which a sheet (for example, polymethylmethacrylate resin, polycarbonate resin, vinyl chloride resin, etc.) is used to form an uneven pattern on the resin surface by hot pressing.

However, in the above injection molding method, although the accuracy of the concave-convex pattern is relatively good, it is difficult to obtain a large number of patterns, and at least 10 per shot.
Since it takes about a second, there is a drawback that productivity is very low. Further, in the hot pressing method, when the uneven pattern is formed on the surface of the thermoplastic resin sheet by hot pressing, the sheet is peeled from the heat roll before being cooled, so that the emboss formability of the uneven pattern is not only bad. However, the rotary method (roll embossing method: FIG. 6), which has relatively good mass productivity, has a problem that the processing speed is about 3 m / min and the productivity cannot be said to be high. Furthermore, when the smoothness of the resin sheet surface is poor, a fine concavo-convex pattern such as pits and pregrooves can be reproduced with good reproducibility.
There is also a problem that it is difficult to form it uniformly.

[0006]

As described above, according to the conventional method, it is not possible to form uneven patterns such as pits and pregrooves uniformly and with good reproducibility, or productivity is low and cost is high. There was a problem that became. The present invention has been made in view of the above problems, and in the method of forming a concavo-convex pattern such as pits and pre-grooves forming an information signal recorded on an optical recording medium, the concavo-convex pattern is uniformly formed. It is an object of the present invention to provide a method for manufacturing an optical recording medium, which can be formed with good reproducibility and fidelity, is remarkably excellent in productivity, and is inexpensive.

[0007]

That is, according to the present invention, a concavo-convex pattern such as pits or pregrooves is formed on the surface of either one of a pair of nip rolls and a cooling roll arranged immediately after the T-die of an extruder. The molten resin extruded from the T-die is attached to the formed stamper (or a laminate in which the molten resin is extruded on the base material sheet supplied from the unwinding roll), Manufacture of an optical recording medium characterized in that the uneven pattern is formed on the resin surface by pressing and cooling between both rolls to form a signal forming surface, and then a light reflecting layer is provided on the signal forming surface. Is the way.

A description will be given below with reference to the drawings. Figure 1
In the present invention, it is a schematic diagram showing a production line of a resin sheet for forming a signal forming surface. In FIG. 1, when the molten resin 5 extruded in a sheet form from the T-die 2 of the extruder 1 is sheet-formed between the cooling roll 3 and the nip roll 4 arranged immediately after the T-die 2. At the same time, the stamper 6 having an uneven pattern such as pits or pregrooves, which is mounted on the surface of either the cooling roll 3 or the nip roll 4, is pressed to form the uneven pattern on the surface of the resin 5. Obtained resin sheet 5
A is wound around the winding roll 9 via the take-up roll 8. As a result, it is possible to continuously obtain the resin sheet 5a on the surface of which the concavo-convex pattern such as pits and pregrooves is formed.

With respect to the resin sheet 5a obtained here,
For example, an optical disc as shown in FIG. 2 is obtained by providing a light-reflecting film layer 12 on the surface on which the concavo-convex pattern is formed, applying a protective coat layer 13 thereon, and then performing label printing on the coat. You can

The present invention can also do the following. That is, as shown in FIG.
On the base material sheet 10 supplied from
-The resin surface extruded from the die 2 is extruded and laminated with the stamper 6 having a concavo-convex pattern such as pits or pregrooves mounted on either surface between the cooling roll 3 and the nip roll 4 to laminate the resin surface. It is possible to continuously obtain the laminated sheet 11 on which uneven patterns such as pits and pregrooves are formed.

FIG. 4 shows a stamper 6 on the surface of the cooling roll 3.
FIG. 3 is an explanatory view in which a main part is enlarged in order to easily understand how to attach and remove the resin sheet extruded from the T-die 2 and simultaneously form the uneven pattern of the stamper 6 on the resin surface.

As described above, according to the present invention, by applying the resin sheet molding technique by the extrusion method, when the uneven pattern such as pits and pregrooves is formed on the resin surface,
Since the reproducibility and the mass productivity are extremely high, the present invention provides a method for manufacturing an optical recording medium which makes it possible to obtain an optical recording medium of high quality at a low cost, and is extremely practical.

The extrusion molding machine 1 and the T-die 2 usable in the present invention are not particularly limited, and a usual resin sheet molding extruder and T-die can be used.

The cooling roll 3 is required to have a function of rapidly cooling the resin 5a having the concavo-convex pattern so as to prevent the concavo-convex pattern from disappearing and being distorted. For example, a metallic roll or the like having a channel through which cooling water circulates can be exemplified.

The nip roll 4 forms an uneven pattern such as pits and pregrooves on the molten resin 5,
It is necessary to press with a sufficient pressure, and it is desirable to use a roll whose surface is made of an elastic material such as urethane or silicon.

As the stamper 6, for example, nickel,
An example is a stamper made of a metal plate produced by plating with gold, chrome, etc., which serves as a master for an uneven pattern such as pits and pregrooves. The thickness of the stamper 6 is
Since it is necessary to have good workability when it is mounted on the cooling roll or the nip roll and to have a strength that can withstand pressing the resin with a sufficient pressure, about 50 to 500 μm is desirable.

As a method of mounting the stamper 6 on the cooling roll 3 or the nip roll 4, a method of fixing with a heat-resistant adhesive, a method of physically fixing with a screw, or a method of using a magnet is used. Any method may be used as long as it does not fall off during processing, such as a method and a method of fixing by vacuum suction. Further, the stamper 6 may be fixed on the entire surface or a part of the cooling roll 3 or the nip roll 4.

Any resin can be used as the resin 5 as long as it can be extruded. For example, polyester resin, polyamide resin, polycarbonate resin, polymethylmethacrylate resin, polymethylpentene resin, ionomer resin, polypropylene resin, polyester sulfone can be used. Resins, vinyl chloride resins, polyurethane resins, polystyrene resins, polyethylene resins, cellulose resins and the like can be used. The thickness is generally 10 μm to 250 μm
The degree is preferable, and in manufacturing, it is determined by the discharge amount of the resin, the processing speed, and the gap between the cooling roll 3 and the nip roll 4.

The base sheet 10 is generally made of a transparent thermoplastic resin such as an acrylic resin such as polycarbonate or polymethylmethacrylate, a cellulose resin such as polyester, polyamide, vinyl chloride or polystyrene. Alternatively, a laminated product thereof can be used. Moreover, since the base material is laminated with the resin 5 extruded from the T-die 2, it is desirable that the base material be a long sheet. The thickness of the substrate is arbitrary, but is usually 10 to 200 μm.
Is.

If necessary, prior to laminating the resin 5 on the base sheet 10, the base sheet 10 may be subjected to surface activation treatment such as anchor coat treatment, corona discharge treatment, and plasma treatment. .

The light reflecting film layer 12 is made of, for example, a metal such as aluminum, gold, silver or tin by a method such as a vacuum deposition method, a sputtering method, an ion plating method or the like.
An example is one having a thickness of about 10000Å.

As the protective coat layer 13, the light reflection film layer 1 is used.
There is no particular limitation as long as it does not affect the reflection characteristic of No. 2, but for example, an ultraviolet curable acrylic resin can be used.

[0023]

Therefore, according to the present invention, as a method for forming a concavo-convex pattern such as pits and pregrooves, a stamper having the concavo-convex pattern formed on the surface of either the cooling roll or the nip roll of the extruder is mounted, By pressing the stamper against the extruded resin,
The embossing moldability of the concavo-convex pattern will be extremely good, and the productivity will be improved, making it possible to mass-produce high-quality optical recording media at low cost.

[0024]

EXAMPLES The present invention will now be described in more detail with reference to examples. <Example 1> Using the apparatus shown in FIG. 1, a stamper 6 having a spirally-patterned concave-convex pattern of 1.6 μm pitch formed on the surface of a cooling roll 3 was fixed with a heat-resistant adhesive. The resin 5 was extruded from the T-die 2 under the following conditions to continuously obtain the resin sheet 5a having the uneven pattern. Then, a light-reflecting film layer is formed on the uneven pattern surface.
An aluminum vapor deposition layer is provided as 12, and further on that,
The protective layer 13 and the printing layer 14 were sequentially provided to obtain an optical disc 20 as shown in the sectional explanatory view of FIG.

Resin to be used: Polycarbonate resin NOVAREX 7030A manufactured by Mitsubishi Kasei Co., Ltd. Extrusion processing conditions (a) device ... Device of FIG. 1 (b) Extruder ... Screw diameter: 60 mmφ (c) Nip roll ... Silicon rubber roll (Rubber hardness 80 degrees) (d) Extruder temperature setting ... (A) Cylinder (not shown) temperature ... 300C (B) Adapter (not shown) temperature ... 300C (C) T-die Temperature: 300 ° C (e) Cooling roll temperature: 20 ° C (f) Nip pressure (air gauge pressure): 4 kgf / c
m ² (g) Extrusion thickness ··· 100 μm (h) Processing speed · · 40 m / min Light reflection film layer (a) Material · · Aluminum (b) Forming method · Vacuum deposition method (c) Thickness · · 500 Å

The optical disc obtained as described above is uniform and has good reproducibility, and is 1.6 μm on the stamper surface.
It was possible to faithfully form an irregular pattern of m-pitch spiral pattern. Furthermore, the productivity is high, and as a result, an extremely inexpensive and highly accurate optical disc can be obtained.

<Embodiment 2> A resin 5 is extruded and laminated on a base material sheet 10 under the conditions shown below in an apparatus as shown in FIG. 3, and a spiral pattern of 1.6 μm pitch is formed on the surface thereof. Then, the aluminum vapor deposition layer 12, the protective coating layer 13, and the printing layer 14 were sequentially provided on the surface on which the uneven pattern was formed in the same manner as in Example 1 to obtain the optical disc 20 shown in FIG.

Resin used: Polycarbonate resin NOVAREX 7030A manufactured by Mitsubishi Kasei Co., Ltd. Base material sheet: Polycarbonate film Thickness 1
00μm (Corona discharge treatment was applied to the laminated surface beforehand) Extrusion processing conditions (a) Equipment ... Equipment of Fig. 3 (b) Extrusion machine ... Screw diameter: 60mmφ (c) Nip roll ... Silicon rubber roll (rubber hardness 80 (D) Extruder temperature setting- (a) Cylinder (not shown) temperature-300 ° C (b) Adapter (not shown) temperature-300 ° C (C) T-die temperature-300 ℃ (e) Cooling roll temperature ··· 20 ° C (f) Nip pressure (air gauge pressure) · 4kgf / c
m ² (g) Extrusion thickness · · 50 μm (h) Processing speed · · 40 m / min Light reflection film layer (a) Material · · Aluminum (b) Forming method · Vacuum deposition method (c) Thickness · · 500 Å

According to the present embodiment, as in the case of the first embodiment, the spiral concave-convex pattern of the 1.6 μm pitch on the stamper surface is formed uniformly and with good reproducibility and faithfully on the resin surface which will be the signal forming layer. It was possible to obtain an optical disc with high productivity, high productivity, extremely low cost.

<Comparative Example> In a rotary type hot press machine as shown in FIG. 6, a stamper 6 mounted on the surface of a thermo roll 15 is applied to the surface of a thermoplastic resin sheet 16 serving as a substrate to have a thickness of 1.6 μm. An uneven pattern having a pitch spiral pattern is formed under the following conditions, and then the aluminum vapor deposition layer 12 is formed on the uneven pattern forming surface in the same manner as in Example 1.
A protective coat layer 13 and a printing layer 14 were sequentially provided to obtain an optical disc 20 as shown in FIG.

Thermoplastic sheet ... Vinyl chloride film Thickness 10
0 μm Heat press condition (a) Equipment ... Equipment of Fig. 6 (b) Heat roll material ... Silicon rubber roll (rubber hardness 80 degrees) (c) Heat roll heating temperature ... 90.degree. C. (f) Nip pressure (air gauge pressure) ) ... 50 kgf /
cm ² (h) Processing speed ··· 3 m / min Light reflection film layer (a) Material · · Aluminum (b) Forming method · Vacuum deposition method (c) Thickness · · 500 Å

1.6 μ in the obtained optical disc
The uniformity and reproducibility of the uneven pattern of the m-pitch spiral pattern was not very good, and a satisfactory signal forming layer could not be obtained. Further, the processing speed was remarkably slow as compared with Examples 1 and 2, and the optical disk was low in productivity and accuracy.

[0033]

[Table 1]

From the above examples, it is clear that the effect of the present invention is very large. Further, in the above embodiment, the case where the present invention is applied to the optical disc has been described, but the present invention is not limited to this, and the same applies to optical video discs, optical cards, and other sheet-shaped optical recording media. Can be applied to obtain the same effect.

[0035]

As described above, according to the present invention, a resin is extruded from a T-die of an extruder and formed into a sheet, and at the same time, a pit or a pre-groove is formed by a stamper mounted on the surface of a cooling roll or a nip roll. Since an uneven pattern such as is formed on the resin surface, the emboss reproducibility and uniformity of the uneven pattern formed on the resin surface can be improved by applying existing equipment almost as it is, that is, a highly accurate signal recording layer. Can be manufactured.

Further, as compared with the conventional method, since the productivity is remarkably excellent, it is possible to provide a method for manufacturing an optical recording medium which is inexpensive and has a very high accuracy.

[0037]

[Brief description of drawings]

FIG. 1 is a schematic view showing a manufacturing line for forming a signal forming surface on a resin sheet.

FIG. 2 is an explanatory cross-sectional view of an optical recording medium.

FIG. 3 is a schematic view showing another manufacturing line for forming a signal forming surface on a resin sheet.

FIG. 4 is an explanatory view showing an enlarged main part of a production line of an optical recording medium.

FIG. 5 is a cross-sectional explanatory diagram of an optical recording medium.

FIG. 6 is a schematic view showing a manufacturing line by a conventional method (hot pressing method).

[Explanation of sign]

 DESCRIPTION OF SYMBOLS 1 ... Extrusion molding machine 2 ... T-die 3 ... Cooling roll 4 ... Nip roll 5 ... Molten resin 5a ... Resin sheet having an uneven pattern 6 ... Stamper 7 ... Unwinding roll 8 ... Take-up roll 9 ... Take-up roll 10 ... Base material sheet 11 ... Laminated sheet 12 ... Light reflection film layer 13 ... Protective coating layer 14 ... Printing layer 15 ... Thermo roll 16 ... Thermoplastic resin sheet 20 ... Optical recording medium

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // B29L 17:00 4F (72) Inventor Akira Tanaka 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Inventor Makoto Arisawa 1-5-1 Taito, Taito-ku, Tokyo Tokyo Toppan Printing Co., Ltd.

Claims (2)

[Claims] 1. A stamper having a concavo-convex pattern such as pits or pre-grooves is mounted on the surface of either one of a pair of nip rolls and a cooling roll disposed immediately after a T-die of an extruder, and the T -By forming a concavo-convex pattern on the resin surface by pressing and cooling the molten resin extruded from the die between both rolls to form a signal forming surface, and then providing a light reflecting layer on this signal forming surface. And a method for manufacturing an optical recording medium. 2. A molten resin extruded from a T-die is laminated on a base material sheet supplied from an unwinding roll, and the laminated body is pressed and cooled between both rolls to obtain the resin. The method of manufacturing an optical recording medium according to claim 1, wherein the uneven pattern is formed on a resin surface.