JPH02252120A - Substrate for recording disk - Google Patents

Abstract

PURPOSE:To obviate the generation of warpage in the substrate for recording disks and the dimensional change liable to arise during long-term use and to improve heat resistance by adopting the laminated structure consisting of a polyether imide resin layer and a polyether sulfone resin layer. CONSTITUTION:The substrate 1 for recording disks is the substrate for magnetic disks for a stationary magnetic disk device having a circular hole at the center and is of the three-layered structure having the polyether sulfone resin (PES) layer 3a in the upper part, the polyether imide resin (PEI) layer 2 in the intermediate part, and the PES layer 3b in the lower part. The PEI layer 2 constitutes a core part C and the PES layers 3a, 3b of the upper and lower parts constitute the skin layer S. The mechanical weak point in the PES layer 3 is compensated by the PEI layer 2 and both of the temp. characteristics and mechanical characteristics required for the magnetic disks are satisfied by adopting such sandwich structure.

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 accuracy 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 come into practical use, and along with this, magnetic disks are required to be smaller, thinner, and lighter.

Therefore, in recent years, injection acid forming has been using resin materials that can be manufactured by compression molding, especially polyethersulfone resin (single resin), in order 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 also come into practical use.

[Problem to be solved by the invention]

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

It is an object of the present invention to provide a recording disk substrate 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 preferably formed of a laminated structure of at least a polyetherimide resin (hereinafter referred to as PEI) layer 2 and a polyethersulfone resin (hereinafter referred to as PES) layer 3. is PEI layer 2
to form the core part C, and PE9 layers 3a, 3
It is characterized by forming a skin part S sandwiching a core part C by b.

[For production]

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

According to the recording disk substrate 1 according to the present invention, the core portion C
PES used for this purpose has an extremely high heat distortion temperature and excellent long-term heat resistance. Furthermore, the glass transition point is as high as 225° C., which almost satisfies the temperature characteristics required for recording disks. 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 2.
Since it is 1.7°C, it is inferior to PES and does not satisfy the temperature characteristics required for recording disks. However, since it has outstanding moisture absorption resistance among thermoplastic resins, it exhibits high mechanical properties.

Therefore, the recording disk substrate 1 formed by laminating two types of resin materials (Zandwich structure) compensates for the mechanical weakness in the PE9 layer 3 with the PET layer 2, and has the temperature characteristics and mechanical properties required for the recording disk. It satisfies both of the following characteristics.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

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

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

The base l has a three-layer structure including a PE9 layer 3a on the top, a PEI layer 2 in the middle, and a PES layer 3b on the bottom.The PEI layer 2 is the core part C, and the upper and lower PE9 layers 3a and 3b are skin layers. It constitutes S.

A predetermined magnetic layer is formed on the surface of this substrate 1 to form a magnetic disk.

Next, the manufacturing method of the disk substrate 1 will be explained in Fig. 2~
This will be explained with reference to FIG.

First, an injection molding machine for molding the substrate 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
A single injection nozzle 14 is provided for common use. Each injection device 1
2.13 are each equipped with a heating cylinder 15.16, and a screw 17.18 is inserted into each heating cylinder 15.16. Therefore, the first injection device 12 uses PES, and the second injection device 13 uses PES.
It has the ability to inject EI individually. on the other hand,
The first injection device 12 includes a resin path 19 and a confluence path 2 facing the injection port 14a via a ball-type check valve 20 that prevents backflow of different molten resins or mixed molten resins.
1, and the second injection device 13 communicates with the resin path 2.
2, and further communicates with the merging passage 21 via a pole-type check valve 23. In addition, a rod valve 24 is provided in the confluence channel 21 to adjust the mixed flow state of different molten resins during injection, and heaters 25 are provided at external predetermined positions from each injection device 12, I3 to the injection nozzle 14. Set up

On the other hand, a mold device 26 is arranged in front of the injection nozzle 14. The mold device 26 consists of a fixed mold 26a that directly contacts the injection nozzle 14, and a movable mold 26b that opens and closes the mold relative to the fixed mold 26a, and each mold 26a and 26b forms a disk for molding the recording disk base 1. shaped cavity 27
is defined.

Further, the center of the cavity 27 communicates with the injection port 14a via a spool 28, and 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 equipping two injection devices 32 and 33 with shutoff valves 34 and 35 for controlling resin filling and backflow, respectively. The function is the injection molding machine 11 shown in Figure 5.
It is similar to

Next, the second method for forming the recording disk substrate 1 will be explained.
This will be explained with reference to FIGS.

The first injection device 12 shown in FIG. 5 includes a PES, and
It is assumed that the second injection device 13 is in a state where each PEI is measured.

First, the first injection device 12 side is controlled to move the screw 17 forward. As a result, the molten resin (PE) inside the heating cylinder 15
S) 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, and a space S is left on the outer circumferential side as shown in the figure.

Note that, at the initial stage of inflow, the unnecessary resin mixture portion and cold slag portion remaining in the spool 28 and the like flow into the recess 29, and therefore do not enter the cavity 27.

Next, before the PES is cooled and solidified, the second injection device 13
control the side and advance the screw 18.

As a result, the molten resin (PE I ) in the heating cylinder 16 flows into the cavity 27 . In this case, as shown in Figure 3, the PES that already exists is in a solidified state on the outside, and the center side is in a flowable state, so the PES
always flows through the center of the PES. Further, the PES is pushed in the radial direction within the cavity 27 by the inflow of PEI.

Thereafter, the first injection device 12 is further controlled to inject PES 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. Also, P
The quantity and arrangement of the ES 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〕

In this way, the recording disk substrate according to the present invention is made of PE
Since it is formed by laminating an I layer and a PES layer, it has the following effects.

- Obtain a recording disk that eliminates 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, etc., while maintaining the advantages of resin, such as workability, lightness, and responsiveness, and can be provided at low cost.

[Brief explanation of drawings]

Fig. 1: A perspective view of a base for a recording disc according to the present invention; Figs. 2 to 4: A sectional view of the inside of a cavity illustrating a method of molding the base for a recording disc; Figs. 5 and 6: the same molding. 1 is a longitudinal sectional view of a part of an injection molding machine in which the method can be carried out; FIG. In the drawing, 1: Recording disk substrate 2: PEI layer 3.3a, 3b
:PES Layer C: Core Part S Niskin Part Patent Applicant Nissei Jushi Kogyo Co., Ltd. Representative Patent Attorney 2 1) Shigeru = 9

Claims (1)

[Scope of Claims] [1] A substrate for a recording disk, characterized in that it is formed by laminating at least a polyetherimide resin layer and a polyethersulfone resin layer. [2] A recording disk substrate characterized in that a core portion is formed from a polyetherimide resin layer, and a skin portion sandwiching the core portion is formed from a polyethersulfone resin layer.