JP2002331551A - Injection-molding die for optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding die for an optical disk wherein the transfer property is increased, and the productivity is not spoiled, and especially, a cooling period of time does not become long, and the transfer property alone is increased without worsening warpage. SOLUTION: At the start of injection during molding, in order to increase the transfer property by delaying an initial cooling for the surface of a stumper, a heat insulating plate of a uniform density, which is detachably located, is included between a supporting body, which receives the stumper, and the stumper. Thus, the transfer property is increased, and as a result, the temperature of the die can be reduced. Therefore, warpage can be reduced. At the same time, shortening the cooling period of time can increase the productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for injection molding an optical disk.

[0002]

2. Description of the Related Art Conventionally, in molding an optical disk, a mold temperature is adjusted to ensure transfer to a molded disk. When the mold temperature is high, the transferability is improved, but the cooling time until the disk is taken out becomes long, and it is difficult to achieve compatibility with the productivity. In addition, when the cooling time is shortened, the warpage of the disk worsens.

[0003]

When the temperature of the mold is adjusted as described above, it is difficult to balance transferability with productivity and productivity.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to improve transferability so as not to impair productivity. In particular, it is an object of the present invention to provide a mold for injection molding of an optical disk that does not prolong the cooling time and improves only the transferability without deteriorating the warpage.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a uniform-density heat insulating material for delaying the cooling rate of the resin on the surface of the stamper at the start of resin injection during molding and improving transferability. An optical disk injection molding die, comprising: a heat insulating material sandwiched between the stamper and a support fixed to the stamper.

The heat insulating plate has a mirror-finished surface in contact with the stamper. Alternatively, the surface has a surface roughness of 0.10 s or less, or the material has a thermal conductivity of 15 w / m · k or less and a hardness of 300 Hv or more, or has a thickness of 0.5 to 2.0 mm. And
Alternatively, the above object can be achieved by using an amorphous carbon material. As a method of fixing the heat insulating material, the center of the stamper and the center of the heat insulating plate are fastened together to the support by a stamper holder, and the outer peripheral portion of the heat insulating plate is sucked and fixed to the support. You are a bettor.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a mold for injection molding an optical disk according to the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a stamper attaching / detaching member, which is mainly composed of a part including a stamper mounting surface 5, a stamper holder 7, and an outer peripheral ring 8. Hereinafter, this one member is defined as a cassette. The cassette 1 is provided with a stamper 6 and a heat insulating plate 15. Reference numeral 3 denotes a fixed mold plate on the side where the stamper is mounted, and 2 denotes a movable mold plate.

FIG. 1 includes a detachable, uniform-density heat insulating plate 15 between a mold temperature control pipe 16 and a stamper 6 of a support for receiving a stamper according to claim 1 of the present invention. The heat insulating plate 15 according to claim 7 of the present invention is fastened together with the center portion of the stamper 6 by the stamper holder 7 to form the heat insulating plate 15.
FIG. 3 is a schematic view showing a state in which a mold cassette in which a stamper 6 and a heat insulating plate 15 can be detached and attached in an off-line manner by a cassette type mold is attached to or detached from the mold by suctioning an outer peripheral portion of the mold.

In the case of molding an optical disk, in order to transfer the resin to a stamper shape, a resin melted to a temperature close to the decomposition temperature of the resin (eg, 330 ° C. or more in the case of polycarbonate) is heated to a temperature below the softening point of the resin (eg, polycarbonate). In case 1
The resin is transferred into a stamper shape in a short time (approximately 0.1 second) and then cooled and solidified (on the order of several seconds), the mold is opened, and the molded body is taken out. When transferring the resin to the stamper shape, it is necessary to lower the viscosity of the resin, and therefore, it is desirable to keep the stamper surface temperature at the time of injection high. At this time, in consideration of productivity, it is preferable that the tact is short, and as a result, the compact is removed from the mold at a temperature higher than the mold temperature. That is, after the molded body is taken out of the mold and before the next resin is injected, the surface temperature of the stamper is affected by the mold temperature and decreases. At this time, by inserting the heat insulating plate 15 between the stamper 6 and the mold temperature control pipe 16, the surface temperature of the stamper until injection can be kept higher, and as a result, the transfer is improved.

At this time, the surface 5 in contact with the stamper surface of the heat insulating plate
By making the mirror finish, the adhesion between the stamper and the heat insulating plate with respect to the molding pressure can be improved by improving the adhesion to the stamper, and the life of the stamper and the heat insulating plate can be extended.

Further, by setting the surface roughness of the surface 5 of the heat insulating plate in contact with the stamper surface to 0.10 s or less, deterioration of the stamper quality due to the transfer of the heat insulating plate surface to the stamper surface due to molding pressure is prevented. The life of the stamper can be extended.

Since the heat conductivity of the mold material is larger than 20 W / m · k, this heat insulating plate is made of a material having a heat conductivity of 15 W / m · k or less and a hardness of 300 Hv or more that can withstand molding pressure. By doing so, the heat insulating effect is large and the transfer at the time of molding injection is improved.

When the thickness of the heat insulating plate is 0.5 mm or less, the heat insulating effect is small and the strength is weak. When the thickness is 2.0 mm or more, the heat insulating effect is not changed.
Heat insulation effect is large by having a thickness of ~ 2.0 mm,
Transfer during molding and injection is improved.

The heat insulating plate is made of amorphous carbon having high strength, high heat resistance, low abrasion, high strength, and low thermal conductivity, so that the transfer can be improved and the life of the heat insulating plate and the stamper can be extended. it can. As an example of amorphous carbon, UNIVEKS ^™ (manufactured by Unitika Ltd.) has a thermal conductivity of 5 to 8 W / m · k and a hardness of 5
It is 00Hv, the bending strength is 100 to 220 Mpa, and the temperature can maintain the amorphous state up to 2600 degrees (all catalog values).

The heat insulating plate 15 is fastened together with the central portion of the stamper 6 by the stamper holder 7 and the outer peripheral portion of the heat insulating plate 15 is suctioned, so that the heat insulating plate 15 is securely fixed to the mold during molding and is stable. As a result, the quality of the molded body is stabilized.

By attaching the heat insulating plate and the stamper to the cassette type mold, when the stamper mounting surface and the heat insulating plate are damaged, they can be easily replaced, so that the manufacturing lead time can be shortened. Also, when molding is performed in a state where foreign matter exists between the back surface of the stamper and the heat insulating plate and the mounting surface of the stamper, the shape of the foreign matter is reduced by the compression force at the time of molding (for example, 15 to 30 Ton in DVD-ROM molding). And when it is transferred to a mold and transferred to a stamper, the transfer is transferred to a molding disk, so that a defective disk is made, which causes a serious defect in product quality and remakes the stamper. . Also, if it is transferred to the stamper mounting surface, it will be transferred to the next stamper unless it is wiped cleanly,
In the case of scratching, the entire surface of the scratch is polished or parts of this portion are remade, which has a serious effect of increasing the manufacturing lead time and increasing the manufacturing cost. However, by using the cassette method, since the stamper mounting surface is included in the cassette, the stamper replacement operation can be performed off-line. Since the work can be performed in an environment that is easy to see, the stamper can be mounted on the stamper mounting surface without any foreign matter, so that the occurrence of bumps due to the foreign matter being sandwiched can be prevented. Also, by performing the stamper replacement work in a place with higher cleanliness,
The occurrence of bumps can be further prevented. By performing molding without bumps, the production lead time can be protected and the production cost can be reduced.

[0018]

As described above, according to the present invention, at the start of injection during molding, in order to delay the initial cooling of the surface of the stamper and to improve the transferability, it is necessary to attach or remove the stamper between the support receiving the stamper and the stamper. By including the heat insulating plate of uniform density positioned in the formula, the transferability is improved, and as a result, the mold temperature can be lowered, the warpage is improved, and the cooling time is shortened to improve the productivity. Provided is a mold for injection molding of an optical disk which can be improved.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 includes a detachably positioned uniform-density heat insulating plate between a mold temperature control pipe of a support for receiving a stamper of the present invention and a stamper, and is used when a cassette is attached to or detached from a mold. Schematic diagram of mold

[Explanation of symbols]

 Reference Signs List 1 cassette 2 movable mold plate 3 fixed mold plate 4 fixed mirror insert 5 stamper mounting surface 6 stamper 7 stamper holder 8 outer ring 9 rotating ring 10 movable mirror insert 11, 13 bolt 12 rotating ring 14 outer suction part 15 heat insulation Plate 16 Mold temperature control piping

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masafumi Kurisu 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 4F202 AH79 AJ01 AJ06 AJ13 CA11 CB01 CK42 CK90 5D121 DD05 DD18

Claims (7)

[Claims] 1. An optical disk injection molding die including a stamper for molding a thermoplastic resin material into an optical disk molded body, wherein a cooling rate of a resin on the surface of the stamper at the start of injection of the resin during molding is delayed. An injection molding die for an optical disc, comprising a heat insulating material having a uniform density for improving transferability, and the heat insulating material is sandwiched between the stamper and a support fixed to the stamper. 2. The optical disk injection molding die according to claim 1, wherein a surface of the heat insulating material in contact with the stamper is mirror-finished. 3. The optical disk injection molding die according to claim 1, wherein a surface roughness of a surface of the heat insulating material in contact with the stamper is set to 0.10 s or less. 4. The heat insulating material according to claim 1, wherein the heat insulating material is 15 w / m ·
2. The optical disk injection mold according to claim 1, wherein the mold has a thermal conductivity of not more than k and a hardness of not less than 300 Hv. 5. The heat insulating material according to claim 1, wherein the heat insulating material is 0.5 to 2.
2. The optical disk injection molding die according to claim 1, having a thickness of 0 mm. 6. The optical disk injection molding die according to claim 1, wherein the heat insulating material is made of amorphous carbon. 7. The heat insulating material according to claim 1, wherein a central portion of the stamper and a central portion of the heat insulating plate are fastened to the support with a stamper holder and the outer peripheral portion of the heat insulating plate is sucked. 2. The optical disk injection molding die according to claim 1, wherein said mold is fixed to said support.