JPH02116040A - Forming metallic mold for optical disk substrate - Google Patents

Abstract

PURPOSE:To improve the optical characteristics of an optical disk substrate to be formed by using a material having the heat conductivity and the linear expansion coefficient equal or approximate to those of a stamper to form a part or the whole of a metallic mold member. CONSTITUTION:The material having the heat conductivity equal or approximate to that of a stamper 2 or the material having the heat conductivity and the linear expansion coefficient equal or approximate to those of the stamper 2 is used to a part or all parts 5-7 and 1 of a metallic mold having a touch to the stamper 2 containing an information pattern. As a result, the resin (optical disk substrate 3) held in a cavity has a reduced degree of a temperature profile even though the temperature is controlled to heat up or cool the metallic mold. Furthermore the coefft. of contraction of the mold is reduced. Thus it is possible to improve the optical characteristics particularly the double refraction index of a disk substrate to be formed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an injection method and a condensation method, which are methods for manufacturing optical disc substrates that can record, reproduce, store, or erase audio, images, information, etc. This product relates to a mold for clamping a stamper with a turn, regardless of whether it is a molding method or a casting method.

[Conventional technology]

Conventional methods for manufacturing optical disk substrates include injection molding of thermoplastic resins such as polycargonate and polymethyl methacrylate into a mold equipped with a metal stamper with information stamping, and compression molding.
There is also a method for molding conderesion, and a method for molding conderection that takes advantage of the advantages of both methods.

In addition, when using a polyvinyl ester-based thermosetting resin, a method of curing by irradiating active energy rays, a method of curing by heating, or a combination of both, that is, a method of combining active energy rays and heating. etc.

Austenitic stainless steel, which has good workability and good corrosion resistance, has been used for the cavity portion of the mold used in these conventional molding methods.

When the above austenitic stainless steel is used for the part where the information arm turn and stun mother is fixed and attached,
Due to its moderate hardness (H!1 = 140-180) and workability, clamp rings can be manufactured with high precision, and it has good corrosion resistance even after use, so it is relatively preferred.

However, in addition to mechanical requirements such as flatness and roughness as a molded product, optical disk substrates are also required to have optical properties such as birefringence.

In order to stably mold a molded product with high reproducibility using a molding die, it is usually necessary to adjust the temperature of the mold.

Then, the above-mentioned austenitic stainless steel mold and stand gloss were positioned, the fixing members such as Hestan/IF, especially the nickel clamps that are currently widely used, were fixed, and the mold temperature was adjusted. In this case, since the thermal conductivity and coefficient of linear expansion of stainless steel and nickel are different, heat is not uniformly transferred to the resin in the cavity that is in contact with both the stainless steel and nickel materials.

As a result, shrinkage rate changes occur in the optical disk substrate after molding due to temperature unevenness, which has an unfavorable effect on optical properties, particularly birefringence.

Also, when the mold is cooled during demolding, the disc substrate cannot be peeled off uniformly due to the difference in thermal conductivity and coefficient of linear expansion.
As a result, patterns may appear on the substrate. When the center hole of the Tokushu Stunno Q fits and the material used to position and fix the stamper is made of stainless steel, a difference in shrinkage rate occurs between the stamper and the core, resulting in a slight difference in the stamper's shine. However, the movement may cause interlayer misalignment between the disk substrate and the stamper.Also, patterns, cracks, and dirt may occur in that area, that is, near the center hole of the disk substrate, resulting in defects in optical characteristics. worsen.

[Problem to be solved by the invention]

The present invention solves the above-mentioned problems of the prior art. Even if the temperature of the mold is controlled such as heating and cooling during molding of a single disk substrate, unevenness in the temperature of the resin (optical disk substrate) in the cavity occurs. It is an object of the present invention to provide a mold for molding an optical disk substrate that is difficult to use, has a small difference in mold shrinkage rate, and has good optical properties, particularly birefringence.

[Ninth means to solve the problem]

In order to solve the above problems, the present invention uses a material having a thermal conductivity equal to or close to the thermal conductivity of the stun gloss for part or all of the mold that is in contact with the information patterned stun gloss.
In addition, it is characterized by applying a material that has the same thermal conductivity and coefficient of linear expansion as Stantsuya, and using a friend mold.

For example, when the clamp 4 is made of nickel, part or all of the mold that the clamp 4 contacts is made of a copper-aluminum alloy.
Alternatively, it is made of industrial pure iron.

Note that, in the present invention, forming a part of the mold includes cases where the surface portion of another material is coated with metal or the like, or where thin plates are laminated. Of course, it also includes a positional table part.

Note that when industrial pure iron is used, it has better corrosion resistance than other carbon steels, but there is a problem with hardness, but it can be treated by surface treatment, for example, plating.

〔Example〕

FIG. 1 shows a partial sectional view of a cast molding die showing an embodiment of the present invention. In the apparatus shown in the figure, methane” (
2) is installed vertically, and the active energy curable resin is injected into the cavity through an upper injection port (not shown). Such a configuration is advantageous because air bubbles trapped inside the resin can be collected upward.

Clamp? (2) is installed in the center of the Stuno Qi17' plate (1), and is aligned with the stamper positioning protrusion (9) provided at the end of the outer bush (5). Holding plate (1) K embedded magnet (
(not shown) or vacuum means (also not shown) K. A slidable middle bush (6) is provided inside the outer pusher (5), and the outer pusher (5) is provided with a slidable middle bush (6).
A gas passage (10) for an inert gas such as N2 is formed between the inner pusher (5) and the inner pusher (6). This gas flow path is used for releasing the disk substrate from the mold, which will be described later. A center bush (7) is further provided inside the middle bush (6) so as to be slidable independently of the middle bush (6). Inside this center bush (7) is the gas flow path (
10) A separate gas flow path (11) is provided. This gas flow path is also used for releasing the disk substrate (3), which will be described later.

The end of the center bush (7) has a diameter that defines the diameter of the hole in the center of the disk substrate (3) to be molded, and also has a diameter that defines the diameter of the hole in the center of the disk substrate (3) to be molded.
) and the glass plate (4) and the reverse teno part 9 (
13).

A flange (12) is provided adjacent to the flange (12) for separating the disc substrate (3) from the stand and motherboard (2).

Figure 2 shows a state in which the middle bushing (6) and center bushing (7) have been moved slightly to the left in the figure from the state shown in Fig. 1. At this time, the end of the center bushing (7) The edge of the center hole of the disk substrate (3) is caught by the reverse chi/mother part (13) (approximately 5 degrees) and pulled slightly to the left with the movement of the center bushing, and as a result, the glass flat plate (4 ). Also, as the center bushing moves, the gas flow path (11) inside the bushing
Pressure gas, for example N2 gas, is ejected from the disk substrate (3) and the glass flat plate (4) to separate them over the entire surface.

Figure 3 shows the view after the glass flat plate (4) has been evacuated.

Move only the center bushing (7) to a position slightly to the right from the state shown in Fig. 1, push out the center of the disk substrate (3) to the right with the flange (12) of the bushing, and push the outer pushbutton ( 5) The end face and stand are peeled off from a part of + (2). At this time, N2f! from the gas flow path (10)! The disk substrate (
3) is completely peeled off from the stamper, (2) and the mold surface.

Is the demolded disk substrate (3) a nine-piece holding a suction tool (14)? It is then transported to another location using a manual (not shown).

In the mold shown in FIGS. 1 to 3, the stamper (2)
111 Nickel, outer bush (5), middle bush (6)
The center bush (7) is made of aluminum brass, which is a copper-aluminum alloy, and the stamper holding plate (1) is made of iron-based material.

Aluminum brass has a thermal conductivity of nickel (0.14 to 0.20
C*l/an-8-'C) Value close to Ic (0,14~0
．． 16C*l/atrS-°C), and has a linear expansion coefficient of nickel (12-14 x 10-'/°C) (15-17 x 10'/l:: ), which is close to that of nickel.
When the temperature of the mold is adjusted, the entire resin in the cavity is heated and cooled almost uniformly, so that the optical properties of the molded disc substrate are good as shown in Table 1.

[Comparative example]

Figure 4 shows the outer bush (5) shown in Figures 1 to 3.
, is a diagram schematically showing the range of influence of optical characteristics when austenitic stainless steel is used for the middle bushing (6), the center bushing (7), and the outer peripheral ring (not shown). This shows that it affects not only the areas in contact with each other, but also other areas. The characteristics of this comparative example are shown in Table 1.

Table 1 [Effect of the invention] Thermal conductivity of the stamper for part or all of the mold member,
By using a material having a coefficient of linear expansion that is the same as or close to it, the optical characteristics of the molded nine-optical disk substrate can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing the main parts of a mold showing one embodiment of the present invention, FIGS. 2 and 3 are views showing the state of demolding,
FIG. 4 is a diagram schematically explaining the influence of the optical characteristics of the disk substrate. 1... Stun, *hold f rate, 2... Stamper,
3... Disk substrate, 4... Glass flat plate, 5...
Outer button, 6... middle button, 7... center button. Agent Patent Attorney Katsutoshi Takahashi Figure 11 Gas flow path Figure 11 Gas RR Figure Hatake-Stamper contact area

Claims (1)

[Claims] 1. An active energy ray-curable resin is injected between the information patterned stamper and the active energy ray-transparent flat plate;
In a mold for a device that manufactures an optical disk substrate by irradiating active energy rays, a part or all of the mold that is in contact with the information patterned stamper has a thermal conductivity that is the same as or close to that of the stamper. A mold for molding an optical disc substrate characterized by using the material. 2. The optical disc substrate molding according to claim 1, wherein the material of the stamper is nickel, and a part or all of the mold in contact with the stamper is made of copper-aluminum alloy or pure iron. Mold. 3. An active energy ray-curable resin is injected between a stamper with an information pattern and an active energy ray-transparent flat plate, and the resin is irradiated with active energy rays to form an optical disc substrate. A mold for molding an optical disk substrate, characterized in that part or all of the mold in contact with the patterned stamper is made of a material having the same thermal conductivity and coefficient of linear expansion as, or close to, those of the stamper.