JPH0463449B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording disk substrate that can be used as a magnetic disk in a fixed magnetic disk device.

[Conventional technology]

Conventionally, as a base for a magnetic disk, one using an aluminum material is known.

This type of base requires high-precision machining of the material in order to ensure surface area and dimensional accuracy, and has problems in machinability and productivity, making it impossible to reduce production costs.

On the other hand, with the development of portable personal computers, battery-powered fixed disk devices have also been put into practical use, and along with this, there has been a demand for smaller, thinner, and lighter magnetic disks.

Therefore, recently, resin materials that can be manufactured by injection molding or compression molding, especially polyethersulfone resin (single resin), have been used to improve processability and productivity, and further reduce production costs. At the same time, magnetic disk substrates that are lighter in weight and have improved functionality based on resin properties have been put into practical use.

[Problem to be solved by the invention]

However, conventional magnetic disk substrates using polyether sulfone resin have issues that need to be resolved, such as being more prone to warping and dimensional changes during long-term use, as well as being weak in heat resistance, compared to aluminum materials. .

It is an object of the present invention to provide a recording disk base that solves the problems existing in the conventional technology.

[Means to solve the problem]

The recording disk substrate 1 according to the present invention is made of at least polyetherimide resin (hereinafter referred to as PEI).
It is formed by a laminated structure of layer 2 and polyether sulfone resin (hereinafter referred to as PES) layer 3. Preferably, the PEI layer 2 forms the core part C, and the PES layers 3a and 3b form the core part C. It is characterized by forming a skin part S that sandwiches the.

[Effect]

Next, the operation of the present invention will be explained.

According to the recording disk base 1 according to the present invention,
The PES used for the core part C has an extremely high heat distortion temperature and has excellent long-term heat resistance. In addition, the glass transition point
The temperature is as high as 22℃, which almost satisfies the temperature characteristics required for recording discs. However, since PES has some hygroscopicity, it tends to warp and has drawbacks in terms of mechanical properties.

On the other hand, PEI used for the skin layer S has a glass transition point of 217° C., which is inferior to PES, and does not satisfy the temperature characteristics required of a recording disk. but,
Among thermoplastic resins, it has outstanding moisture absorption resistance and exhibits high mechanical properties.

Therefore, the recording disk base 1 is made by laminating these two types of resin materials (Sandermanch structure).
The mechanical weakness of the PES layer 3 is compensated for by the PEI layer 2, thereby satisfying both the temperature characteristics and mechanical characteristics required of a recording disk.

〔Example〕

Below, preferred embodiments according to the present invention are listed,
This will be explained in detail based on the drawings.

First, the structure of the recording disk base 1 will be explained with reference to FIG.

The illustrated recording disk base 1 is a magnetic disk base for a fixed magnetic disk device, and is formed into a donut shape with a circular hole in the center.

The base 1 has a three-layer structure with a PES layer 3a on the top, a PEI layer 2 in the middle, and a PES layer 3b on the bottom,
The PEI layer 2 covers the core part C, and the upper and lower PES layers 3
a and 3b constitute a skin layer S.

A predetermined magnetic layer is formed on the surface of this substrate 1,
It becomes a magnetic disk.

Next, a method of manufacturing the disk substrate 1 will be explained with reference to FIGS. 2 to 6.

First, an injection molding machine for forming the base 1 will be explained with reference to FIGS. 5 and 6.

The injection molding machine 11 shown in FIG. 5 includes two injection devices consisting of a first injection device 12 and a second injection device 13, and also includes a single injection nozzle 14 for common use. Each injection device 12, 13 is provided with a heating cylinder 15, 16, respectively, and a screw 17, 18 is inserted into each heating cylinder 15, 16. Therefore, the first injection device 12 has the function of individually injecting PES, and the second injection device 13 separately injecting PEI. On the other hand, the first injection device 12 is connected to the injection port 14 through the resin path 19 and further through a ball type check valve 20 that prevents backflow of different molten resins or mixed molten resins.
The second injection device 13 communicates with the merging passage 21 facing the point a, and also communicates with the merging passage 21 via the resin passage 22 and a ball-type check valve 23. In addition, in the confluence channel 21, there is a rod valve 24 for adjusting the mixed flow state of different molten resins during injection.
In addition, a heater 2 is provided at a predetermined external position from each injection device 12, 13 to the injection nozzle 14.
5... is arranged.

On the other hand, a mold device 26 is located in front of the injection nozzle 14.
Allocate. The mold device 26 consists of a fixed mold 26a that is in direct contact with the injection nozzle 14, and a movable mold 26b that opens and closes the mold with respect to the fixed mold 26a.
A disk-shaped cavity 27 for molding the recording disk base 1 is defined by 6a and 26b. Also, the center of the cavity 27 is the spool 28.
communicates with the injection port 14a via the
A recess 29 for retaining unnecessary resin is provided on the surface of the cavity 27 facing the spool 28.

On the other hand, the injection molding machine 31 shown in FIG. 6 is constructed by two injection devices 32 and 33 equipped with shut-off valves 34 and 35 for controlling resin filling and backflow, respectively, and has basic functions. is similar to the injection molding machine 11 shown in FIG.

Next, a method of forming the recording disk base 1 will be explained with reference to FIGS. 2 to 4.

The first injection device 12 shown in FIG. 5 includes a PES,
Further, it is assumed that PEI is weighed in each of the second injection devices 13.

First, the first injection device 12 is controlled to move the screw 17 forward. As a result, the molten resin (PES) in the heating cylinder 15 flows into the cavity 27 through the spool 28, as shown in FIG.
The inflow amount at this time is a part of the cavity capacity,
As shown in the figure, a space S is left on the outer circumferential side. In addition, at the beginning of the inflow, unnecessary resin mixed parts and cold slag parts remaining in the pool 28 etc. are in the recess 2.
9, it does not enter the cavity 27.

Next, before the PES is cooled and solidified, the second injection device 13 is controlled to move the screw 18 forward. As a result, the molten resin (PEI) in the heating cylinder 16 flows into the cavity 27. In this case, as shown in FIG. 3, the outside of the existing PES is in a solidified state and the center is in a flowable state, so PEI always flows through the center of the PES. Also,
The PES is pushed radially into the cavity 27 by the inflow of PEI.

After this, the first injection device 12 side is further controlled.
PES is injected to completely fill the cavity 27 with resin in preparation for the next molding cycle.

On the other hand, unnecessary spools, concave portions, etc. are removed from the cooled and solidified molded product taken out from the mold device 26. As a result, the recording disk substrate 1 shown in FIG. 1 is obtained.

Although the embodiments have been described in detail above, the present invention is not limited to these embodiments. For example, although a magnetic disk is illustrated, the present invention can be similarly applied to any other recording disk such as an optical disk. Further, the quantity and arrangement of the PES layer and PEI layer can be changed as necessary. Other details such as the configuration can be arbitrarily changed without departing from the gist of the present invention.

〔Effect of the invention〕

As described above, since the recording disk substrate according to the present invention is formed by laminating the PEI layer and the PES layer, it has the following effects.

To obtain a recording disk which can eliminate the drawbacks of conventional resin disks, such as eliminating warping of the recording disk, and has excellent both temperature characteristics (heat resistance) and mechanical characteristics.

Since the base can be integrally molded with resin, it can be mass-produced by injection molding or the like while maintaining the advantages of resin, such as workability, lightness, and responsiveness, and can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1: A perspective view of a recording disk base according to the present invention, FIGS. 2 to 4: A cross-sectional view of the inside of a cavity illustrating a method of forming the same recording disk base, FIGS. 5 and 6: The same FIG. 1 is a longitudinal sectional view showing a part of an injection molding machine that can carry out the molding method. In the drawing, 1: Recording disk base, 2: PEI
Layer, 3, 3a, 3b: PES layer, C: Core part, S:
Skin department.

Claims (1)

[Scope of Claims] 1. A recording disk base comprising a laminated layer of at least a polyetherimide resin layer and a polyethersulfone resin layer. 2. A recording disk substrate characterized in that a core portion is formed of a polyetherimide resin layer, and a skin portion sandwiching the core portion is formed of a polyethersulfone resin layer.