JPS6259014A - Mold for molding disc-type recording medium - Google Patents

Abstract

PURPOSE:To mold a replica disc, in which the deflection of surface, warpage or the like is seldom generated, stably and simply by a method wherein a cavity insert and a core insert are provided with the first temperature regulating groove for flowing a first heat medium and a second temperature regulating groove for flowing a second heat medium on the back surfaces thereof. CONSTITUTION:Two threads of spiral temperature regulating grooves are arranged on a cavity insert 1' and a core insert 1'' in the same manner while heat mediums, having different temperatures, are poured into a first temperature regulating groove 2 and a second temperature regulating groove 3. The cavity insert 1' and the core insert 1'' are kept in a temperature higher than a glass transition point by the heat medium, poured into the first temperature regulating groove 2 and set in a temperature higher than the glass transition point of the resin. The pouring of the heat medium into the first temperature regulating groove 2 is stopped simultaneously with the finish of filling of the resin into the cavity and the heat medium, having a temperature higher than the thermal deformation temperature of the resin, is poured into the second temperature regulating groove 3. The resin, loaded in the cavity, is cooled to a temperature lower than the thermal deformation temperature thereof and a prominent replica disc, on which an information signal inscribed on a stamper is transferred faithfully, may be obtained.

Description

[Detailed description of the invention] Industrial applications The present invention is a video disc and a compact disc.

The present invention relates to a mold for forming a disk-shaped recording medium for manufacturing a replica plate of a disk-shaped recording medium (hereinafter referred to as a disk) such as an optical memory disk.

Conventional technology In recent years, video discs and compact discs.

The development of optical memory disks and the like is actively progressing, and injection molding is mainly used as a manufacturing method for disks, with the aim of reducing costs and improving quality.

Conventionally, a disc mold has a cavity insert 31. as shown in FIG. Equipped with a core insert 32,
The stencil stamper 33 on the cavity insert 31 is fixed by a center holder 34 and an outer circumference presser ring 36. A temperature control groove 36 is provided on the back surface of the cavity insert 31 and the core insert 32 to maintain the mold at a constant temperature. It functions to cool the resin injected into the tee to a certain temperature.

Problems to be Solved by the Invention However, in conventional disk molding molds, there is only one system of temperature control grooves in the mold, so it is necessary to set the temperature of the heat medium to the temperature at which the molded replica plate is taken out. I don't get it. For this reason, when the resin is injected into the cavity, the molten resin immediately cools down to the temperature at which it is taken out, resulting in a problem in that signal transferability deteriorates. If the mold temperature is set to a temperature that provides sufficient transferability, the temperature of the replica plate taken out from the mold will be high, and the replica plate will have surface runout, warp, etc. during the cooling process, resulting in a replica with poor characteristics. It becomes a board.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a first temperature control groove through which the first heat medium flows and a second temperature control groove through which the second heat medium flows on the back surface of the cavity insert and the core insert. The feature is that two temperature control grooves are provided independently.

Effect of the present invention With the above configuration, a heat medium having a temperature equal to or higher than the glass transition point of the resin flows into the first temperature control groove provided on the back surface of the cavity insert and the core insert, and the mold temperature is adjusted to the temperature of the resin. By keeping the temperature above the glass transition point, when the cavity is filled with molten plasticized resin,
Information signals engraved on the stamper can be faithfully transferred.

Immediately after the filling of the resin into the cavity is completed, the flow of the heat medium into the first temperature control groove is stopped, and at the same time, the flow of the heat medium into the second temperature control groove is started. The temperature of the heat medium flowing into the second temperature control groove is set to be below the thermal deformation temperature of the resin. When the heat medium flows into the second temperature control groove, the resin in the filled cavity is cooled by 1, and by the time it is taken out from the mold, it has been cooled to below the heat distortion temperature. , less occurrence of surface runout, glue, etc. As a result, a replica board with excellent properties can be stably and easily formed.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the diagram, insert 1
has two spiral temperature control grooves 2 and 3 on the back surface. 2 is the first
3 is a first temperature regulating groove into which a heat medium flows, and 3 is a second temperature regulating groove into which a second heat medium flows. The above-mentioned two spiral temperature control grooves are arranged in the same way on the cavity insert and the core insert, and heat medium with different temperatures is allowed to flow into the first temperature control groove and the second temperature control groove, respectively. do. FIG. 2 shows a plan view of the temperature regulating grooves 2.3 provided in the insert 1.

FIG. 3 is an overall view of the mold including the insert. 1′
is a cavity insert, and 1'' is a core insert. 2 and 3 are the first . This is the second temperature control groove. Reference numeral 4 denotes a stamper on which information signals are recorded, and this stamper 4 is fixed onto the cavity insert 1' by a center pin 5 and an outer circumferential holding ring 6. The molten plasticized resin passes through the sprue 7, passes through the gate 8, and is filled into the cavity.

The cavity insert 1' and the core insert 1
'' is maintained at a temperature higher than the glass transition point of the resin flowing into the first temperature control groove 2 by a heating medium set at a temperature higher than the glass transition temperature.

At the same time as the filling of the resin into the cavity is completed, the flow of the heat medium into the first temperature control groove 2 is stopped, and the heat medium set at a temperature equal to or lower than the thermal deformation temperature of the resin is introduced into the second temperature control groove 3. Inflow. The resin filled in the cavity is cooled to below its heat distortion temperature, and then taken out from the mold by a takeout device as shown in the figure.

A replica board is formed through the series of steps described above.

Effects of the Invention As described above, the present invention provides two independent systems of temperature regulating grooves in the cavity insert and the core insert, and by flowing two types of heat medium with different temperatures into the temperature regulating grooves, the stamper can be heated. It is possible to form an excellent replica board that faithfully transfers the information signals engraved on the board and has less surface runout and warpage.

[Brief explanation of drawings]

Figure 1 shows the first and second molds on the back surface used in the mold of the present invention.
FIG. 2 is a plan view of the insert including the temperature control grooves, FIG. 3 is an overall view of the disk molding die including the insert provided with the temperature control grooves of the present invention, FIG. 4 is a side view of a conventional molding die. 1...Insert, 1'...Cavity insert, 1''...Core insert, 2
...First temperature control groove, 3 ... Second temperature control groove, 4 ... Stamper, 5 ... Center holder, 6 ... ...Outer presser ring, 7...
・Sprue, 8...Gate. Name of agent: Patent attorney Toshio Nakao and 1 other person3-
'%24 = Fig. 2 f'-5 and ゛F1-I〉Gate f''--JI〉7-F?
4-1 Sugunno X. , I-1-t; Tar wide rudder 6--01 pusher 2-des 7--, 8-m-gate Fig. 4

Claims (1)

[Claims] A first temperature control groove through which the first heat medium flows and a second temperature control groove through which the second heat medium flows are independently provided on the back surfaces of the cavity insert and core insert that form the cavity of the mold. A mold for forming a disc-shaped recording medium.