JPH081811A - Method for molding substrate for optical information recording medium and stamper for optical information recording medium - Google Patents

Abstract

(57) [Abstract] [Purpose] An optical information recording medium that enables sheet formation with low birefringence and a high transfer rate, and that prevents birefringence that occurs at the time of striped pattern perpendicular to the sheet flow direction and release. Provided is a method for molding a substrate for use with a stamper for an optical information recording medium. [Structure] Multiple systems of heat medium are made to flow through the cooling roll equipped with a stamper to control the temperature of the roll in several stages, or multiple blocks are provided perpendicular to the rotation direction of the cooling roll equipped with a stamper. (EN) A method for molding a substrate for an optical information recording medium in which the temperature of the stamper surface is controlled in blocks by a built-in heater separate from a mechanism for adjusting, and a stamper for an optical information recording medium in which a part or the whole of the stamper is a heating element.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art An optical recording medium substrate for optically recording / reproducing information is provided with unevenness of a guide groove for tracking and fine preformat patterns such as address information bits. Conventionally, an injection molding method and a compression molding method are known as methods for forming a substrate having these preformat patterns.
Further, there is a roller grouping method by continuous extrusion molding as a method for molding a substrate having a preformat pattern at a high speed and in a large amount. This is a thermoplastic resin that is heated and melted by an extruder and extruded from a T-die.
It is passed between a mirror surface roll and a stamper roll to form a sheet, and at the same time, the preformatted concavo-convex pattern is transferred to the resin surface to continuously form a substrate for an optical information recording medium such as an optical disk, an optical card or an optical tape. Is the way.

Specifically, FIG. 3 shows, as a roller grouping method, a manufacturing apparatus for molding a substrate for an optical recording medium by transferring to a molding resin an uneven shape such as a guide groove or a preformat pattern by a three-roll method. It is a schematic diagram,
1 is an extruder, 2 is a T die, 3 is a first roll for molding,
4 is a second roll (stamper roll), 5 is a third roll, 6 is a heat-melted resin sheet, and 7 is a molded sheet to which a preformat pattern is transferred.

The heat-melted resin sheet 6 extruded in a sheet form from the T die 2 of the extruder 1 is guided between a first roll 3 and a stamper roll (second roll) 4, and here, both rolls 3, While being pressed by 4, the shape of the stamper 8 attached to the outer peripheral surface of the stamper roll 4 is transferred. After the transfer, the resin sheet 7 passes between the third roll 5 and the stamper roll 4, and is then taken by the take-up machine 9. When the resin sheet molded by such a method is used as a substrate for an optical recording medium, it is desired that the birefringence of the substrate be as small as possible.

In order to form a substrate having a low birefringence, it is desirable to raise the resin temperature as much as possible and lower the resin viscosity when sandwiching the molten resin between the first roll and the second roll.

For this reason, the transferability is improved by forming the temperature of the three rolls as close as possible to the softening point temperature of the thermoplastic resin, and further by providing a heat insulating layer between the stamper and the roll. In addition, a substrate having low birefringence can be manufactured.

[0007]

However, in the above conventional example, the resin temperature at the time of sandwiching the resin between the first roll and the second roll is much higher than the softening point temperature of the resin, and the temperature of each roll is also different from that of the resin. Since the temperature is close to the softening point, the formed sheet is transferred from the second roll to the third roll with insufficient cooling of the sheet on the second roll (stamper). At this time, the formed sheet adhered to the stamper and became difficult to be peeled off, which caused a striped pattern in the direction perpendicular to the flow direction of the sheet or a new birefringence at the time of peeling. This phenomenon was conspicuous when the heat insulating layer having a large specific heat was interposed.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and the gist of the method of forming a substrate for an optical information recording medium of the present invention is to extrude a thermoplastic resin into a sheet. At the same time, in an extrusion molding method of transferring the preformat pattern onto a sheet by a cooling roll having a stamper having a concavo-convex preformat pattern, a plurality of heating mediums are placed in the cooling roll having the stamper attached. The thermoplastic resin is formed into a sheet by a molding method and an extrusion molding method for a substrate for an optical information recording medium, which is characterized in that the temperature of the roll is controlled in several steps, and at the same time, by a cooling roll equipped with a stamper having a preformat pattern. Extrusion molding method for transferring the preformat pattern onto a sheet In this case, several to several tens of blocks are provided perpendicularly to the rotation direction of the cooling roll having the stamper attached, and the temperature of the roll stamper surface is blocked by a built-in heater separate from the mechanism for adjusting the temperature of the roll. In the molding method of a substrate for an optical information recording medium, which is characterized in that the sheet molding is performed while controlling separately, and the cooling roll for extrusion molding of the above-mentioned 2 invention,
A method for molding an optical information recording medium substrate, characterized in that the introduced portion of the sheet is at a higher temperature than the derived portion, and a stamper for producing the optical information recording medium substrate having an uneven preformat pattern on the substrate surface. Wherein, the stamper for producing an optical information recording medium substrate having a preformat pattern and a stamper for an optical information recording medium, characterized in that a part or the whole of the stamper is made of a thermoplastic resin Of the stamper and stamper surface for optical information recording media, which are used for the extrusion molding method (roller grouping method) in which the pre-format pattern on the stamper is transferred onto the sheet at the same time as the sheet is formed. Light characterized by molding while reversibly changing temperature A stamper for the broadcast recording medium.

The present invention will be described in detail below.

FIG. 1 is an explanatory view showing an example of an apparatus used in the method for molding a substrate for an optical information recording medium according to the first invention.

In FIG. 1, the cylinder in which the heat medium flows in the roll to which the stamper is attached is divided into two, and two systems of heat medium are flowed into the same roll.

The forming roll is generally divided into an outer cylinder forming an outer shell and an inner cylinder having a temperature control mechanism. As the base material of the outer cylinder, all commonly used metals, carbon, and the like are used, but it is preferable to use metals such as carbon steel and duralumin because the surface requires hardness. The surface of the roll may be plated with chrome or the like and polished to a mirror surface, or may be surface-treated with a fluororesin or the like. To give the roll a sufficient temperature gradient,
The heat of the heat medium flowing through the roll must be quickly transferred to the roll surface, and for that purpose, it is preferable that the thickness of the roll base material is thin. However, if the roll is too thin, the roll strength becomes weak and the roll may be deformed. Therefore, the wall thickness of the roll is 25 mm or less, preferably 15 to 20 mm.

In FIG. 1, 10 is a high temperature control zone, 1
Reference numeral 1 denotes a low temperature control zone, which divides the inner cylinder of the roll having the stamper into two. What is necessary when dividing is that the temperature of the stamper surface is raised at the moment when the resin in a heat-melted state enters and is sandwiched between the two rolls,
This is to lower the temperature of the stamper surface when the sheet solidified on the stamper and having the pattern transferred thereto is peeled off from the stamper.

That is, a high-temperature heat medium is generated immediately after the sheet is separated from the stamper until the heat-melted resin is sandwiched, and a low-temperature heat medium is formed immediately after the resin is sandwiched and the sheet is separated from the stamper. If it is divided into two parts so that the flow will flow, it becomes possible to form a substrate that solves the above problems.

FIG. 2 is a schematic view showing an example of means for flowing two systems of heat medium in the forming roll. A heat medium for adjusting the temperature of the roll is flowing through the inner cylinder 12 of the forming roll, and the heat medium entering from the heat medium introducing port 13 at the center is transferred to the transfer pipe 15.
To the surface side of the roll, reciprocates several times perpendicularly to the rotation direction of the roll, and then is discharged from the central discharge port through another transmission pipe.

Here, as shown in the figure, the heat medium inlet port 13 is divided into two systems by a heat medium dividing wall 14. These are fixed regardless of the rotation of the roll so that a specific position always has a specific temperature. The transmission pipe 15, the inner cylinder 12, and the outer cylinder 16 are made to rotate integrally.
This makes it possible to control the temperature to a specific temperature at a specific position regardless of the rotation of the roll. By providing a similar mechanism on the heat medium discharge port side, the temperature of the heat medium can be controlled more effectively.

Next, a stamper having a concavo-convex preformat pattern for an optical information recording medium is attached to the roll surface having such a mechanism.

The concavo-convex preformat pattern for the optical information recording medium on the stamper surface is prepared by a conventionally known method such as a conventionally known photolithography method or direct engraving. Further, even if the stamper is manufactured by a method of transferring the preformat pattern onto the base material using these as a mask (FIG. 7) or a method of simultaneously forming and transferring the base material and the preformat pattern by a pressing method or an electroforming method. Good (Figure 8). It is also possible to directly provide a preformat pattern on the roll, which is subjected to processing such as engraving.

FIG. 4 is a view showing an example of an extrusion molding roll used in the method for molding an optical information recording medium substrate of the second invention of the present invention, and FIG. 5 (a) is a sectional view thereof.

As the base material of the molding roll 1, all commonly used metals, carbon and the like are used. However, since the surface requires hardness, carbon steel, duralumin and other metals are used. good. The surface of the roll may be plated with chrome or the like and polished to a mirror surface, or may be surface-treated with a fluororesin or the like.

A temperature adjusting mechanism 42 for the entire roll is provided inside the roll, and in this example, a mechanism for flowing a heat medium is provided.

In the vicinity of the roll surface, a heater 43 according to the present invention, which is divided into blocks perpendicular to the rotation direction of the roll, is embedded. In this example, the block is divided into eight according to the pattern of the optical information recording medium.

These heaters can be temperature-controlled for each block and may be turned on / off in accordance with the rotation of the roll.

In the present embodiment, a current collecting contact 46 provided on the side surface of the roll is provided by a conductor 45 from the heater of each block.
It is possible to turn on the heater at a specific position by rotating the roll so that the current can be taken from the current collecting brush 47 according to the rotation of the roll.
Specifically, on each block, an electric current is passed through the heater built into the roll from immediately after the sheet is separated from the stamper until the heat-melted resin is sandwiched, and the sheet is immediately inserted after the resin is sandwiched. The position of the current collecting brush was set so that no current would flow through the heater built into the roll until it was separated from the stamper.

In this way, the temperature of the stamper surface can be raised locally for each block, so that the set temperature of the roll itself can be set lower by 10 to 40 ° C. than the conventional temperature, and the temperature of the formed sheet can be reduced. It is advantageous in terms of releasability.

Next, a roll-shaped stamper is manufactured using the above rolls. The concavo-convex preformat pattern for the optical information recording medium on the stamper surface is produced by the same method as the first invention shown in FIGS.

In this example, the thickness obtained by electroforming nickel on the pattern surface on the mother mask having the uneven preformat pattern for the optical information recording medium and releasing the electroformed layer from the mother mask A 150 micron nickel stamper as shown in FIG. 6 was wound on a roll and mechanically fixed to obtain a roll stamper.

Next, a stamper for an optical information medium according to the third invention will be described.

The concavo-convex preformat pattern for the optical information recording medium on the stamper surface is the first pattern shown in FIGS.
It may be produced by a method similar to that of the invention and the second invention of FIGS.

As the base material of the stamper, a metal having a large electric resistivity, for example, Bi, Ni-Cr alloy, Ni-C is used.
An r-Fr alloy, a Cu-Mn-Fe alloy, a metal oxide such as tin oxide, indium oxide, cadmium tin oxide, or the like can be used.

A stamper roll made of these materials is mounted on the roll as shown in FIG. 5 to produce a self-heating stamper roll. At this time, in order to enable temperature control for each block of the stamper, the length of the stamper should be smaller than the length of the roll in the circumferential direction so that several or dozens of stampers can be arranged in the circumferential direction of the roll. . Further, in order to control the temperature of each block of the stamper independently, it is necessary to make the surface of the cooling roll or the back surface of the stamper an insulating layer. A sheet of polyimide or the like may be interposed between the roll and the stamper. A contact 46 for current collection is provided on the side surface of the roll so that current can be taken in from the current collecting brush 47 according to the rotation of the roll.

Each temperature control block on the roll stamper thus provided is controlled in accordance with the rotation of the roll.

In FIG. 5, the temperature of the stamper surface is raised at the moment when the resin in the heat-melted state enters and is sandwiched between the two rolls, while the sheet cured on the stamper is peeled from the stamper surface. It is desirable to lower the temperature of.

Therefore, an electric current is applied to the stamper used as a heat source from immediately after the sheet is separated from the stamper until the heat-melted resin is sandwiched, and the stamper is provided from immediately after the resin is sandwiched until the sheet is separated from the stamper. Prevent current from flowing. Current on-o
It is easy to control ff according to the rotation position of the roll by using a current collecting brush provided on the side surface of the roll.

As described above, since the heater-like stamper provided on the surface of the roll has a small heat capacity, the temperature of the stamper surface can be locally and rapidly changed. It is possible to effectively form a substrate using two heat sources together by always setting a temperature slightly lower than the softening point temperature of the resin, for example, 10 to 40 ° C. even on the roll itself to which the stamper is attached.

[0036]

【Example】

Example 1 A roll stamper having a flexible stamper attached was used as the second roll of the extrusion molding machine (FIG. 3) described above, and a sheet was extruded by an extruder having a diameter of 65 mm (300 mm width T die) to form a substrate. Molded. At this time, the temperature inside the extruder was 270 ° C and the temperature of the T die was 300 ° C.

The first roll temperature is 135.degree. C., the second roll temperature is 170.degree. C. in the high temperature control zone and 11 in the low temperature control zone.
0 ° C, the temperature of the third roll was set to 110 ° C, and the heat-melted polycarbonate resin (Teijin Kasei, Panlite L-12
25) is extruded from the T-die and the take-up speed is 4.0 m / m
in, and a polycarbonate resin substrate having a preformat pattern for an optical information recording medium (thickness: 0.
4 mm) was obtained.

During molding, the temperature of the stamper surface was set by a radiation thermometer.
The temperature was 0 ° C., which was 115 ° C. immediately after the sheet was separated from the stamper, which was almost equal to the set temperature of the heat medium.

The sheet-like substrate for an optical recording medium thus obtained had a single path with a birefringence of 20 nm or less, and the transfer was also complete. Also, by the time the seat leaves the stamper,
Since the pattern transfer surface of the molded sheet is cooled to the set temperature on the low temperature side of the roll, it is possible to prevent the occurrence of the striped pattern caused by the sheet adhering to the stamper, and it is possible to prevent it from occurring at the time of mold release. It also prevented the occurrence of new birefringence.

Further, by these effects, it becomes possible to mold the substrate at a higher temperature and a higher speed.

Example 2 A flexible stamper obtained as shown in FIG. 5 was attached, and 8 corresponding to the pattern of the stamper was attached.
A roll with two heaters inside is used as the second roll of the extrusion molding machine (Fig. 3) described above, and a sheet is extruded by an extrusion machine (T die of 300 mm width) with a diameter of 65 mm to form a substrate. did. At this time, the temperature inside the extruder was set to 270 ° C. and the temperature of the T die was set to 300 ° C., and the melted polycarbonate resin (Teijin Kasei, Panlite L-1225) was extruded, and
The temperature of the first to third rolls is 125 ° C due to the circulation type temperature control oil.
Was set, and molding was performed at a take-up speed of 4.0 m / min to obtain a polycarbonate resin substrate (thickness 0.4 mm) having a preformat pattern for an optical information recording medium.

At the same time, the heater built in near the surface of the roll in this section was heated from immediately after the sheet was separated from the stamper until the heat-melted resin was sandwiched. The temperature of the stamper surface where the heater is present can be locally controlled. The temperature of the stamper surface immediately before sandwiching the resin was 170 ° C, and the stamper surface temperature at the moment when the sheet separated from the stamper was 120 ° C. .

The sheet-like substrate for an optical recording medium thus obtained had a birefringence of 20 nm or less in a single pass and was completely transferred. Immediately after sandwiching the heat-melted resin, the heater built into the roll is turned off,
Before the sheet leaves the stamper, it returns to the temperature set by the temperature control oil of the roll, so it is possible to prevent the occurrence of the striped pattern that was caused by the sheet sticking to the stamper at the time of release, and a new It was also possible to prevent birefringence from occurring.

Further, by these effects, it becomes possible to mold the substrate at a higher temperature and a higher speed.

Example 3 First, as shown in FIG. 9 (a), a 25-micron-thick polyimide sheet 21 was bonded onto a Ni-Cr-Fe alloy 20 having a 100-micron-thick plate shape. Then, a photoresist (WAYCOAT HP
R204 (manufactured by Fuji Hand Electronics Technology Co., Ltd.) was dropped and applied with a spinner to a film thickness of 3000 Å, and then prebaked at 100 ° C. for 20 minutes to form a photoresist layer 22.

Next, a laser exposure device [mirror projector mask aligner. An exposure apparatus such as MPA-1500 (manufactured by Canon Inc.)] was used to expose a predetermined pattern (striped pattern) of a plurality of information recording media (FIG. 9).
(B)).

Next, when developed with an LSI developer (manufactured by Fuji Hand Electronics Technology Co., Ltd.), the photoresist 23 where the ultraviolet light hits flows away, and the resist 24 where the ultraviolet light does not hit remains, and the tracking groove,
A flexible pattern having a linear tracking track pattern for optical cards with a width of 3 μm and a pitch of 12 μm is formed by forming a fine pattern of unevenness such as information bits on the alloy 20 and finally cutting the outer periphery into a rectangle of 120 × 120 mm. Stamper 8 was obtained. (FIG. 9C) Eight stampers were prepared, and as shown in FIG.
They were attached side by side on a roll circumference of 00 mm. The stamper was fixed by screwing both ends, and a conductive screw was used on one side and an insulating screw was used on the other side. The conductive screw side has the ground to the roll, the insulating side screw side has the conductor 45 from the stamper, and the side of the roll has a contact 4 for collecting electricity.
6 is provided so that the current can be taken from the current collecting brush 47 according to the rotation of the roll. All of these wirings are insulated from the roll which is the ground electrode.

In this way, the temperature of the stamper surface can be controlled for each of the eight blocks.

The roll-shaped stamper to which the flexible stamper having a self-heating property is attached, which is obtained as described above, is used as the second member of the above-mentioned extruder (FIG. 3).
Extruder with a diameter of 65 mm (300
The sheet was extruded by a T-die having a width of mm) to form a substrate. At this time, the temperature inside the extruder is 270 ° C, T
The temperature of the die was set to 300 ° C. and the melted polycarbonate resin (Teijin Kasei, Panlite L-1225) was extruded, and the temperature of the first to third rolls was set to 125 ° C. by the circulation type temperature control oil, Pickup speed 3.0m / min
And a polycarbonate resin substrate having a preformat pattern for an optical information recording medium (thickness 0.4 m
m) was obtained.

At the same time, a current of 100 V and 6 amperes was applied to the stamper, and the stamper in this section was heated immediately after the sheet was separated from the stamper until the heat-melted resin was sandwiched. In this way, since the heater-like stamper provided on the surface of the roll has a small heat capacity, the temperature of the stamper surface can be locally and rapidly changed, and the temperature of the stamper surface immediately before the resin is sandwiched is 170 ° C. The surface temperature of the stamper at the moment when the sheet separated from the stamper was 125 ° C.

The sheet-like substrate for an optical recording medium obtained had a birefringence of 20 nm or less in a single pass and the transfer was perfect. Immediately after sandwiching the heat-melted resin, by turning off the self-heating mechanism of the stamper,
Before the sheet leaves the stamper, it returns to the temperature set by the temperature control oil of the roll, so it is possible to prevent the occurrence of striped pattern that was caused by the sticking of the sheet to the stamper, and new birefringence occurs at the time of release. I was able to prevent that.

[0052]

EFFECTS OF THE INVENTION As described above, the heating medium of a plurality of systems is caused to flow through the cooling roll having the stamper to control the temperature of the roll in several stages, or the cooling roll having the stamper attached thereto can be operated in a direction perpendicular to the rotating direction of the cooling roll. The temperature of the roll stamper surface is controlled for each block by a built-in heater of a system different from the mechanism for adjusting the temperature of the roll by providing one to several tens of blocks, and the temperature of the resin when sandwiching the resin is raised, and Since the sheet can be efficiently cooled when it separates from the same roll, it is possible to form the sheet with low birefringence and high transfer rate, and
Adhesion that occurred when the formed sheet was transferred from the roll to the third roll, that is, a striped pattern perpendicular to the sheet flow direction,
There is an effect that birefringence newly generated at the time of releasing the mold can be prevented. Further, by using a part or the whole of the stamper for manufacturing a substrate for preformatting unevenness on the substrate surface as a heating element, it is possible to similarly raise the resin temperature when sandwiching the resin. Moreover, since the sheet can be cooled on the stamper only by controlling the on-off of the heating element, the sticking that occurs when the molded sheet is transferred from the second roll to the third roll, that is, the sheet flow direction, There is an effect that vertical stripes and birefringence newly generated at the time of peeling can be prevented.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an apparatus according to a method for molding a substrate for an optical information recording medium of the present invention.

2 (a) and 2 (b) show an example of means for flowing a plurality of heating mediums in a molding roll according to the method for molding a substrate for an optical information recording medium of the present invention. ′ Sectional view and B-
B'sectional view.

FIG. 3 is a schematic diagram of a roller grouping molding method according to a molding method of a substrate for an optical information recording medium of the present invention.

FIG. 4 is a schematic view showing an example of a forming roll according to the forming method of the present invention.

5 (a) and 5 (b) are a sectional view and a side view showing an embodiment of a forming roll according to the forming method of the present invention.

FIG. 6 is a view showing a stamper used in an embodiment of the second invention of the present invention.

FIG. 7 is a sectional view showing a form of a stamper according to the present invention.

FIG. 8 is a cross-sectional view showing another form of the stamper according to the present invention.

FIG. 9 is a process drawing showing the method of manufacturing a stamper according to the present invention.

10 (a), (b) and (c) are a perspective view, a side view and a BB sectional view showing an example in which a stamper according to the present invention is attached to a molding roll.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Extruder 2 T die 3 1st roll for molding 4 2nd roll (stamper roll) 5 3rd roll 6 Resin sheet in a heat-melted state 7 Molded sheet to which a preformat pattern is transferred 8 Stamper 9 Take-off machine 10 High temperature temperature control Zone 11 Low-temperature control zone 12 Inner cylinder 13 Heat medium inlet port 14 Heat medium dividing wall 15 Heat transfer pipe 16 Outer cylinder 17 Preformat pattern 18 Stamper fixture 19 Exothermic base material 20 Exothermic alloy 21 Heat resistant sheet 22 Photoresist layer 23 Exposed part 24 Non-exposed part 41 Forming roll 42 Roll temperature adjusting mechanism 43 Roll built-in heater 44 Temperature control block 45 Conductor wire 46 Current collecting contact 47 Current collecting brush 48 Heater operating area 49 Heater inactive area

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Claims (6)

[Claims] 1. A method for molding a substrate for an optical information recording medium having a concavo-convex preformat pattern on a substrate surface, wherein a thermoplastic resin is formed into a sheet by extrusion molding, and at the same time, a stamper having the preformat pattern is attached. In an extrusion molding method in which the preformat pattern is transferred onto a sheet by a cooling roll, it is possible to control the temperature of the roll in several steps by flowing a plurality of systems of heating medium into the cooling roll equipped with the stamper. A method for molding a substrate for an optical information recording medium, which is characterized. 2. A method for molding a substrate for an optical information recording medium having a concavo-convex preformat pattern on the surface of the substrate, wherein the thermoplastic resin is formed into a sheet by extrusion molding and, at the same time, a stamper having the preformat pattern is attached. In the extrusion molding method in which the preformat pattern is transferred onto a sheet by a cooling roll, several to several tens of blocks are provided perpendicularly to the rotation direction of the cooling roll with the stamper, and the temperature of the roll is adjusted. A method for forming a substrate for an optical information recording medium, characterized in that sheet formation is performed while controlling the temperature of the roll stamper surface in blocks by a built-in heater separate from the mechanism for performing the above. 3. An optical information recording medium according to claim 1, wherein the cooling roll for extrusion molding according to claim 1 or 2, wherein the introduction portion of the sheet has a higher temperature than the extraction portion. Substrate molding method. 4. A stamper for manufacturing a substrate for an optical information recording medium having a concavo-convex preformat pattern on the surface of the substrate, characterized in that part or the whole of the stamper comprises a heating element. Stamper for information recording media. 5. A stamper for producing a substrate for an optical information recording medium having a preformat pattern is wound around an extrusion molding roll of a thermoplastic resin, and the preformat pattern on the stamper is formed on the sheet simultaneously with sheet formation. The stamper for an optical information recording medium according to claim 4, which is used in an extrusion molding method for transferring. 6. The stamper for an optical information recording medium according to claim 4, wherein the stamper surface is molded while reversibly changing the temperature.