JPS6280828A - Magnetic disc - Google Patents

Abstract

PURPOSE:To prevent an adhered part from being exfoliate due to deformation or lapse of time by using a non-solvent type adhesives for the adhered art between a base of a magnetic disc and a flexible disc so as to reduce the time required for the adhesion between the base and the disc. CONSTITUTION:A flexible disc 2 comprising a support 4 and a magnetic layer 5 is sticked to one face or both faces of the base of the magnetic disc via a gap 3 and a rotary shaft driving the disc 2 is inserted to the center hole 7. The non-solvent type adhesives is used for the adhesive part between the disc 1 of the magnetic disc and the disc 2. Then the time required to bond the base and the disc 2 is reduced and exfoliation of the adhered part due to lapse of time and deformation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic disk used for in-plane or perpendicular magnetic recording.

[Conventional technology]

Conventionally, a rigid magnetic disk has been used as one type of magnetic disk, and a rigid material with little flexibility is used as the base of this magnetic disk.

Aluminum (for example, JIS ksotrb) is usually used as the base of a rigid magnetic disk.

Such rigid magnetic disks are generally manufactured by turning aluminum using a lathe, reducing the space between the head and the disk, polishing the disk surface to enable high-density recording, and then applying vapor deposition or spin coating. It is made by providing a magnetic layer by et al. In this case, for high-density recording and reproduction, the smoother the surface roughness of the disk, the better, but it is difficult to obtain a surface with a center line average roughness Ra of 0.1 μm or less with conventional aluminum-based disks. there were. Furthermore, since the base lacks flexibility, there are restrictions such as the inability to continuously coat the web when providing a magnetic layer. Furthermore, since the influence of dust adhering to the surface is significant for high-density recording, discs must be made to prevent dust from adhering to them, making the time-consuming process even more troublesome and complicated, and requiring huge capital investment. I made it something to do.

In addition, conventional substrates, typically made of aluminum, are rigid and therefore inflexible, meaning that when the head traces the magnetic layer of the disk, it must be non-contact, and this gap remains narrow. It is difficult to maintain a constant value, often causing signal errors, and it has been extremely difficult to further reduce the space between the head and the disk surface in order to further increase the recording density in the future. - In the unlikely event that the head accidentally comes into contact with the disk surface due to tracing with a narrow spacing, a large impact force will be concentrated on the contact surface between the head and the magnetic layer because the base is rigid. This causes surface damage and shortens the life of the disk.

Saram, as mentioned above, has the disadvantage that the aluminum base itself is expensive.

In response to this, recently, wide annular recesses have been provided on both sides of the disk base, and floppy disks or flexible disks (hereinafter collectively referred to as "flexible disk sheets") that have a magnetic layer on the negative side have been created with the magnetic layer on the surface. A magnetic disk has been proposed that is bonded to both sides of a base, with a gap between the flexible disk sheet, the back surface, and the base.

This type of magnetic disk has a flexible magnetic recording surface, so even if the head happens to come into contact with the magnetic recording surface, or even if the head comes into contact with the magnetic recording surface, recording at a higher recording density is possible. However, unlike rigid disks, the magnetic layer is less likely to be damaged. The flexible disk technology can be applied directly to this friend, and a magnetic layer with a smooth surface and durability can be used as the magnetic layer for the magnetic disk, so it is attracting attention as a device that can eliminate the drawbacks of conventional rigid magnetic disks. There is.

[Purpose of the invention]

The purpose of the present invention is, firstly, to obtain a magnetic disk in which the adhesive portion between the base and the flexible disk does not peel off due to aging or deformation; secondly, to obtain a magnetic disk that can be bonded instantly; The object of the present invention is to obtain a flexible magnetic disk without sagging.

[Structure of the invention]

The above object is achieved by the following magnetic disk.

(1) In a magnetic disk in which a flexible disk having a magnetic layer on one surface of a non-magnetic support is attached to at least one side of the substrate with a gap between the back surface of the disk and the substrate, the adhesive may be used as an adhesive. A magnetic disk characterized by using a solvent-free adhesive.

The present invention will be explained in detail below.

The magnetic disk targeted by the present invention has seven surfaces or both surfaces (
The one shown has a support ≠ and a magnetic layer j on both sides with a gap 3 between them.
A flexible disk λ consisting of the following is attached.

Note that 7 is a center hole into which a rotating shaft for rotating the disk is inserted.

As the flexible disk λ used in the present invention, materials used for so-called floppy disks can be used. As the support for the flexible disk, a plastic film such as polyethylene terephthalate is used, and a λ-axis oriented polyethylene terephthalate film (PET) is preferable. In particular, a λ-axis oriented polyethylene terephthalate film provided with a magnetic layer has a shrinkage rate of 0.2% or less after heat treatment at approximately 70"C for a time of ≠, and the difference in shrinkage rate in the vertical and horizontal directions is 0.1%. Hereinafter, preferably 0.05 inch or less is preferable.

t7'c, as a support for a flexible disk, Ra (center roughness) of at least the side on which the magnetic layer is provided is 0,
The length is preferably 13 m or less, and by using such a support, the recording density of the final product, the magnetic disk, can be increased.

The magnetic layer provided on the support can be applied not only by applying magnetic iron oxide or ferromagnetic alloy powder together with a binder, but also by paper deposition methods such as vacuum evaporation, sintering, ion blating, plating methods, etc. It is also possible to form friendships.

As the disk substrate used in the present invention, for example, the one whose cross-sectional shape is illustrated in FIGS. 1 and 2 is used.

Gap 3 is between the head and the magnetic layer! When they come into contact, it disperses the frictional force and increases durability, and the magnetic layer! This is provided for the purpose of making it possible to make contact with the head appropriately and to make the width extremely narrow, thereby enabling high-density recording. As a friend, the depth d of the gap 3 needs to be at least θ, /I11 or more. In addition, if there is a gap 3, the influence of dust attached to the magnetic layer B seems to be less, although the cause is not clear.

Although FIG. 7 and FIG. 2 show the case where the inner and outer peripheral edge portions 6 are horizontal, they may be inclined.

Furthermore, the inner and outer diameters of the base and the size of the peripheral edge can be arbitrarily selected depending on the purpose of use.

As the material of the base, metals such as aluminum and aluminum alloys, glass, synthetic resins, filler-containing resins, or combinations thereof are used at least in the heat treatment step.

The next requirement is that it be inexpensive.

In the present invention, even if aluminum, which is a representative metal, is used for the substrate, as shown in Figure 1, the magnetic layer is not affected by the surface roughness of the substrate, so polishing accuracy is not required so much, The cost does not have to be large.

Polymer substrates are generally inexpensive because they can be manufactured in large quantities by injection molding.

Furthermore, in order to avoid deformation when stored at high temperatures, we use crystalline polymers that are heat resistant or that have a glass transition temperature of
Non-quality polymers having a molecular weight of 0c or higher are preferred. Specific examples of the material include polycarbonate, polyetherimide, polyphenylene sulfide, polysulfide, polyimide, polysulfone, polyacrylate, polyethersulfone, polyetherimide, polyetheretherketone, and the like.

In addition, in order to reduce the value of the expansion coefficient of the substrate, TiO2
, 5i02 or the like, BaSO4+ glass fiber, or the like may be mixed in an amount of j to 3j.

The thickness of the base in the present invention is /~jl'l, and the thickness of the flexible disk to be pasted is generally 70 to 100 μm.Since the dimensional stability of the magnetic disk is controlled by that of the base, the size of the base is It is preferable to choose one with good stability.

Aluminum is usually used as the material for the arm of a magnetic head, so the thermal expansion coefficient of the base is the value of aluminum (2,
The closer to Hiroshi × 10-57'C) and the smaller the coefficient of hygroscopic expansion, the better.

The flexible disk is adhered to the above-mentioned base, and the hot melt adhesive uses base polymers such as polystyrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polystyrene-in-prene copolymer,
Seven or more types of rubber resins such as ethylene butylene copolymer, polyisobutylene, polybutadiene, butyl rubber, or polyolefin copolymers such as polyethylene, polypropylene, ethylene vinyl acetate copolymer, butyl acrylate vinyl acetate copolymer, etc. is used.

Furthermore, as tackifying agents to be added to the pace polymer, natural resins such as rosin, polymerized rosin, hydrogenated rosin, rosin ester and their modified products, aliphatic, ring group, aromatic, petroleum resins, and terpene resins are used. Softeners include process oils, phenolic resins, coumaron resins, etc.
e Rough-in oil, castor oil, polybutene, polyisoprene, etc. are used.

Furthermore, additives such as fillers, anti-aging agents, and ultraviolet light inhibitors are added to the hot-melt adhesive as necessary to improve heat resistance, weather resistance, and the like.

These orientation ratios are 100 to 100 parts by weight of the tackifier and 0 to 10 parts by weight of the softener to the amount of base polymer iooM.
0 parts by weight, but the softening point is /'t00C or less, preferably /λO0C or less, and the melt adhesion is /Hiroo'C/
000 poise or less, preferably itooC/
000 poise or less.

In order to enhance the adhesive effect, grooves or holes may be provided in the adhesive part of the base. The thickness of the adhesive layer is 1 to IOQ m, preferably 3 to 20 m.

Also, when bonding, on one or both of the surfaces to be bonded,
Physical surface treatments such as corona discharge, glow discharge, flame treatment, etc. may be applied to facilitate adhesion.

After adhesion, it is also possible to perform heat treatment to remove the anisotropy of the support of the flexible disk.

The temperature of the heat treatment is preferably at least the glass transition point of the support of the flexible disk/20° C. or less, and the time may be set from 2≠hours to 3 seconds depending on the temperature. After heat treatment, cool to room temperature.

Hereinafter, the present invention will be fully explained in detail with reference to Examples, but the scope of the present invention is not limited.

Example [Preparation of flexible disk] A magnetic liquid having the following composition was coated on one side of a co-axis oriented polyethylene terephthalate film support with a thickness of 3 j μm so that the thickness of the magnetic layer after drying and calendering was 7.5 μm. , dried, calendered, provided with a magnetic layer, and punched into a donut-shaped sheet to produce a flexible sheet.

Magnetic liquid ■ γ-F6203 300 parts by weight PVC-
Ac (vinyl chloride-vinyl acetate copolymer) (VYHHUCC Company H) '10tiL part Epoxy resin (Epicote 100/manufactured by Shell Chemical Co., Ltd.) 30 parts by weight Polyamide (Persamide//j Manufactured by GM) 20 parts by weight Methyl Ibutyl Ketone /Kijirol<2//) zoos quantity [Adjustment of base] On the other hand, a base made of polyetherimide containing 30 g of glass fiber was formed by injection molding, and the shape of the t0 base was as shown in Fig. 1. The outer diameter and inner diameter of the disk substrate were respectively / j OTR and the length of the part A to which the μθ crane was attached was 21121. Furthermore, the thickness of the base and the depth d of the gap 3 were 0.2jn.

The above flexible disk and the substrate were attached using the following adhesive, and the evaluation results are summarized in Table 1.

Example 1 Polyisoprene/styrene copolymer Calyflex TR/ /θ/ (manufactured by Shell ■) 100 parts Tackifier Alicyclic petroleum resin alcohol P-70 (manufactured by Arayo Kagaku ■) λoo part Softening ratio softener g Rough-in oil ≠oH approx. 1 Place a flexible disk on top of about 1 layer and o. the edges with soo 0c. It was crimped for r seconds.

Comparative Example 1 (Thermosetting epoxy resin) 100 parts of epoxy resin (Epicote fλ manufactured by Shell ■) Triethylamine! The coating was applied to the edge of the substrate to a thickness of approximately 10 μm, a flexible disk was placed on top of the coating, and the coating was left at t, ooc and jhr.

Comparative Example 2 (Solvent-based) Styrene-butadiene copolymer On methyl ethyl ketone 300 parts Dry film thickness 10 μm
Apply it to the edge of the base, dry it at 100°C for 10 seconds, then place a flexible disk on it and heat it at 60°C.
So I left it at jhr.

Adhesion test method Mylar tape was attached to a flexible magnetic disk and peeled off at 1ro0c. [Effects of the Invention] The magnetic disk of the present invention takes less time to adhere to the base and the flexible disk, and has good adhesion.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a magnetic disk of the type targeted by the present invention, and FIG. 2 is an enlarged view of the edge. The adhesive layer is between the Hiro support and the I base. Patent Applicant Fuji Photo Film Co., Ltd. Figure 1 Figure 2 July 1, 1986
No. 2, Title of the invention Magnetic disk 3, Address of the person making the amendment 1210 Nakai, Minamiashigara City, Kanagawa Prefecture ""
-'・,)I-・・'&Kakuyaku〒IOG Takuji (Miyakominato-ku Nishi-Azabu 21'1lZG No. 5o-Simi story (406j 2537 4, Subject of amendment "Detailed description of the invention" column of the specification 5. Contents of the amendment (1) Insert "Hot-melt adhesives are particularly preferred as solvent-free adhesives" after "Shimeruno debuto," line 6 of the first page of the specification. (2) Doso No. On page 73, the line [alcohol p-70j is corrected to read "Alcon p-70".

Claims (1)

[Claims] In a magnetic disk in which a flexible disk having a magnetic layer on one side of a non-magnetic support is attached to at least one side of a base with a gap between the base and the base, a solvent-free adhesive is used as the adhesive. A magnetic disk featuring