JPS6280829A - Magnetic disc - Google Patents

Abstract

PURPOSE:To reduce the time required for bonding and to improve the adhesion performance by using an acrylic adhesives or a rubber adhesives for the bonding between a base and a flexible disc and applying radiant ray irradiation to the adhesive part. 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 1 of the magnetic disc 7 via a gap 3 and a rotary shaft driving the disc 2 is inserted to a center hole 7. A acrylic adhesives or a rubber adhesives is used for the adhesives of an adhered part between the base 1 and the disc 2. Further, a radiant ray such as electron ray, gamma ray or beta ray is irradiated to the part adhered by the adhesives. Then the time required for bonding is reduced, the exfoliation of the bonded part due to lapse of time or deformation is prevented to improve the bonding performance.

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.

Usually, an aluminum disk (for example, JIS AjOro) is used as a base for a rigid magnetic disk.

Such rigid magnetic disks are generally made entirely of aluminum using a lathe, the space between the head and the disk is made small, and the disk surface is polished to enable high-density recording, followed by vapor deposition and spinning. It is made by providing a magnetic layer by coating or the like. 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 forming a magnetic layer. Furthermore, since the influence of dust adhering to the surface is significant for high-density recording, disks must be made to prevent dust from adhering to them, making an already time-consuming process even more troublesome and complicated, and requiring a huge amount of capital investment. I was making it a thing.

Furthermore, 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 spacing remains narrow. It is difficult to maintain a constant level, 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. On the other hand, if the head happens to come into contact with the disk surface due to a narrow spacing, a large impact force is likely to be concentrated on the surface where the head and the magnetic layer contact, since the base is rigid. , surface destruction occurred, shortening the life of the disk.

Furthermore, there is a drawback that the polished aluminum substrate itself is expensive.

In contrast, 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") with a magnetic layer on the negative side have been created with the magnetic layer on the surface. A magnetic disk has been proposed in which a flexible disk sheet is bonded to both sides of a base, and a fin is provided 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. For this reason, flexible disk technology can be applied as is, and a magnetic layer with a smooth surface and durability can be used as the magnetic layer for magnetic disks, so it is attracting attention as a solution that can overcome the drawbacks of conventional rigid magnetic disks. .

[Purpose of the invention]

That is, the objects of the present invention are, firstly, to obtain a magnetic disk in which the bonded portion between the base and the flexible disk does not peel off due to aging or deformation, and secondly, to obtain a magnetic disk that can be instantly bonded. Third, there is the need to obtain money from magnetic disks without any consideration for flexible disks.

[Means to solve problems]

The above object is achieved by the following magnetic disk.

fil 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, using an acrylic adhesive as an adhesive. A magnetic disk characterized in that it uses a heat-sensitive adhesive or a rubber-based adhesive and is further irradiated with radiation.

The present invention will be explained in detail below.

The magnetic disk to which the present invention is applied can be used in one view or both sides (
In the illustrated example, a flexible disk 2 consisting of a support and a magnetic layer is pasted on both sides with a gap 3 in between.

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

As the flexible disk disc 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 biaxially oriented polyethylene terephthalate film (PET) is preferred. Especially 2Q1111
An oriented polyethylene terephthalate film provided with a magnetic layer has a shrinkage rate of 0.2- or less after heat treatment at approximately 700C for a time of ≠, and the difference in shrinkage rate in the vertical and horizontal directions is 0.
．． The content is preferably 1% or less, preferably 0.01% or less.

Furthermore, as a support for a flexible disk, Ra (center roughness) of the side on which the magnetic layer is provided should be at least 0.7.
It is preferable that it is .mu.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 j provided on the support can be formed not only by applying magnetic iron oxide or ferromagnetic alloy powder together with a binder, but also by vacuum deposition, snow ξ tuttering, ion blating, etc., and by plating. It may be formed by a method or the like.

As the disk substrate used in the present invention, for example, one having a cross-sectional shape 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! It is provided for the two purposes of making contact with the head in an appropriate manner and making the groove extremely narrow, enabling high-density recording. Ninth, the depth d of the gap 3 must be at least 0.1 m. In addition, if there is a gap 3, the influence of dust attached to the magnetic WI 6 seems to be less, although the cause is not clear.

Although FIGS. 1 and 2 show the case where the inner and outer peripheral edge portions t are horizontal, they may be inclined.

Further, the inner diameter and outer diameter of the base and the size of the peripheral portion B can be arbitrarily selected depending on the purpose of use.

As the base material, metals such as aluminum and aluminum alloys, glass or synthetic resins, and filler-containing resins may be used in combination.

The next requirement is that it be inexpensive.

In the present invention, even if aluminum, which is a typical metal, is used for the substrate, as can be seen from FIG. The costs required for such things do not need 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, it is necessary to use a crystalline polymer with a heat-resistant metal or a glass transition point of I.
Non-grade polymers with rooC or higher are preferred. Specific examples of materials include polycarbonate, polyetherimide,
Examples include polyphenylene sulfide, polysulfide polyimide, polysulfo/, polyacrylate, polyether sulfone, polyether imide, and polyether ether ketone.

In addition, in order to reduce the value of the expansion coefficient of the substrate, TiO2
, metal oxides such as SiO2, BaSO4, glass fibers, etc. may be mixed in an amount of 3 to 31% by weight.

The thickness of the base in the present invention is /y! r mm, the thickness of the flexible disk to be pasted is 10 to 100 μm
Generally, the dimensional stability of the magnetic disk is determined by that of the substrate, so it is preferable to select a substrate with good dimensional stability.

The material of the arm of the magnetic head is usually aluminum, so the thermal expansion coefficient of the base is the value of aluminum (2,
The closer to Hiroshi X/<7-5/'C) and the smaller the hygroscopic expansion coefficient, the better.

The flexible discla is bonded to the above-mentioned base, and acrylic adhesives include ■ natural resins such as rosin, polymerized rosin, hydrogenated rosin, and rosin ester, and their modified products, aliphatic, alicyclic, and petroleum. Tackifying resins such as resins and chilled resins, terpenes, phenolic resins, coumaron resins, butyl acrylate/vinyl acetate copolymers, ethylene/vinyl acetate copolymers, etc./more than 7 wt% of species, acrylic acid, methacrylic One or more acrylic monomers such as acids, acrylic esters such as methyl acrylate, butyl acrylate, ethyl methacrylate, tetrahydrofurfuryl acrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and triethylene glycol diacrylate, and methacrylic esters ( A mixture with J-Hiro Owt Chi).

■ Copolymer compositions of acrylic acid, isooctyl acrylate, etc. (syrup after the polymerization rate is stopped at about 10%).

■ Urethane elastomers and polyester oligomers with acryloyl groups at the end of the side chain and/or main chain.

■ Acrylic monomer jXuO in the above ■60~0%
wt%, tackifying resin 0-30% or softener 0-2
Compositions containing 0% rubber adhesives include rubber resins such as polybutadiene, acrylonitrile butadiene copolymer, natural rubber, styrene butadiene rubber, and adhesives such as 7-enolterbene and hydrogenated rosin. Applied resin/
A composition prepared by mixing and dissolving at least one species of acrylic monomer such as acrylic acid, acrylic ester, or methacrylic ester or a vinyl monomer such as vinyl acetate can be used. Plasticizers, fillers, etc. may be added to these adhesive systems as necessary.

Grooves or holes may be provided in the base to enhance the adhesive effect. The thickness of the adhesive layer is /-100μ, preferably 3~
θμm.

Further, during adhesion, one or both of the surfaces to be adhered may be subjected to physical surface treatment such as corona discharge, glow discharge, flame treatment, etc. to facilitate adhesion.

These adhesives are applied to the edges (inner and outer peripheries) of the base plate and to the flexible disk, and then the flexible disk is bonded to the base and irradiated with radiation.

As the radiation to be irradiated in the present invention, electron beams, gamma rays, beta rays, etc. can be conveniently used, but electron beams are preferable. As the electron beam irradiation machine, either a scanning type or a non-scanning type can be employed. For the Nariko line, the acceleration voltage is 700 to 10QOkv
1 good'! shi<har lr.

~300kV"'C, absorbed dose: o, i-,
zOMrad, preferably 0. From j/j Mrad. When the accelerating voltage is less than 100 kV, the amount of energy transmitted is insufficient, and when it exceeds 1000 kVf, the energy efficiency used for polymerization decreases, making it uneconomical. As absorbed dose, 0. /Mrad or less, the curing reaction is insufficient and the strength of the magnetic layer cannot be obtained, and if it exceeds 20Mrad, the energy efficiency used for curing decreases, the irradiated object generates heat, and especially the plastic support of the flexible disk. This is not desirable because it deforms.

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 above the glass transition point of the support of the flexible disk and below 1.200 C, and the time may be set from 2≠hours to 3 seconds depending on the temperature. After heat treatment, cool to room temperature.

EXAMPLES Hereinafter, the present invention will be specifically explained 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 3 j μm thick λ-axis oriented polyethylene terephthalate film support so that the thickness of the magnetic layer after drying and calendering was 13 m. , dried, calendered, provided with a magnetic layer, and punched into a doughnut-shaped sheet to produce a flexible sheet 11.

Magnetic liquid I PFe203 300 parts by weight PVC-
Ac (vinyl chloride-vinyl acetate copolymer) (VYHHU
(manufactured by CC) ≠ 0 parts by weight Epoxy resin (Epicoat 10Ol manufactured by Shell Chemical Co., Ltd.)
≠ ON amount Polyamide (Persamide//! Made by GM) 20 parts by weight Methyl isobutyl ketone/Kizilol (2//)? 00
Part by Weight [Adjustment of Base] On the other hand, a base made of polyetherimide containing glass fiber fJO was formed by injection molding.

The shape of the base is as shown in Figure 1, the outer diameter and inner diameter of the disk base are /30xx, respectively, and the length of the part to be pasted at ≠O is 2fi, and the thickness of the base is j.
m, and the depth d of the gap 3 was O, cojn.

The above flexible disk and base were bonded together using the following adhesive: The average results are summarized in Table 1.

Example 1 Hydrogenated rosin 7! 1 part acrylic acid 20 parts ethylene glycol diacrylate! Film thickness lOμ at the base edge
Apply it so that it becomes m, place a flexible disk on it, and /
Irradiated with A j k V/OMRrad.

Example A copolymerized syrup of 30 parts of coacrylic acid and 70 parts of isooctyl acrylate (polymerization rate f10%) was used to obtain a magnetic disk in the same manner as in Example.

Example 3 Polyurethane acrylate elastomer (AroniX/100 manufactured by Toagosei ■) 70 parts acrylic acid
10 parts terpene resin
A magnetic disk was obtained in the same manner as in Example 2c.

Example μ Acrylonitrile-butadiene copolymer (Nippon Zeon ■, Nippon Zeon Corporation, 70 parts butyl acrylate) 20 parts Vinyl acetate 1Q parts A magnetic disk was obtained in the same manner as in Example 1.

Comparative example/(thermosetting epoxy resin) Epoxy resin Epicoat try (manufactured by Shell ■) Loo part Ditriethylamine J part Coated on the edge of the base to a thickness of about 10 μm, and a flexible disk gold was placed on top of it and left for Jhr. .

Comparative Example 2 (solvent-based) Styrene-butadiene large polymer 700 parts Methyl ethyl ketone, 300 parts Dry film thickness: 70
Coat it on the substrate image area so that it is μm / dry it for 70 seconds at θθ0C, then put a flexible disk on it to 0c
I left it for thr.

Adhesion test method My Y-tape was attached to a flexible magnetic disk and peeled off at lrO°C. This was repeated 0 times and the state of peeling at the edges was observed.

Table 1 Examples/Adhesive! ! ! 4 Time required for adhesion λ
Good/Within paper≠ Comparative example/' z A part of the edge was peeled off.

〔Effect 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. Patent applicant: Fuji Photo Film Co., Ltd. No. 1 Decoy No. 2

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, an acrylic adhesive or a rubber adhesive is used as the adhesive. A magnetic disk characterized in that it is further irradiated with radiation.