JPH03176881A - Magnetic disk - Google Patents

Abstract

PURPOSE:To obtain high durability over a long period of time under wide temp. conditions by forming liners of non-woven fabrics having the structures of plural layers, incorporating rayon fibers into the parts of the non-woven fabrics in contact with a magnetic recording medium and incorporating magnetic powder of a hexagonal crystal system into magnetic layers. CONSTITUTION:The disk-shaped medium 1 is provided with the magnetic layers 38 via under coating layers 37 on both surfaces of a nonmagnetic base 36. The liners 31, 32 are provided with outside layers 33, 34 on both surfaces of inside layers 35. The liners 31, 32 are formed of the non-woven fabrics and at least the parts 33, 34 of the non-woven fabrics in contact with the magnetic recording medium 1 contain >=30 wt.% rayon fibers. The magnetic layers 38 contain the magnetic powder 9 of the hexagonal crystal system. The disk having the excellent durability over a long period of time under a wide range of the temp. conditions is obtd. in this way.

Description

[Detailed description of the invention] B. Industrial application field The present invention relates to a magnetic disk.

Information recording elements are an essential element in conventional information processing systems, and in particular, magnetic recording in such systems already has a considerable amount of technology accumulated, is inexpensive compared to other recording methods, and is This is the mainstream in this field because the recording is non-volatile. Moreover, dramatic improvements in performance and recording capacity continue, recording and reproducing devices are becoming smaller and thinner, recording elements are becoming thinner and smaller, and demand for magnetic disks with shorter access times is increasing. .

For example, a floppy disk is used for magnetic recording as described above, which consists of a disk-shaped magnetic recording medium having a magnetic layer containing magnetic powder and a binder, and a medium cleaning medium that can come into contact with the magnetic layer. A liner is placed inside the case. The above-mentioned liner is generally made of non-woven fabric, which is made by, for example, mixing rayon long fibers with spherical beads such as polypropylene or polyester fibers, heating and melting the beads and fibers, and connecting the rayon long fibers. be.

However, conventional rayon-based nonwoven fabrics have a single-layer structure, and although they have relatively good cleaning properties, they often generate resin powder and feathers that are detached from the nonwoven fabric, causing dropouts. Conversely, ingredients other than rayon (e.g. polyester fiber or polypropylene) that suppress the occurrence
If it increases, the cleaning performance deteriorates, the magnetic layer is damaged, and dropouts increase.

On the other hand, the disk-shaped medium inserted into the case has a magnetic layer on a non-magnetic support with magnetic powder dispersed in a binder.
As density increases, there is a strong demand for improved durability and reliability. In order to increase the density, it is necessary to reduce the spacing between the magnetic head and the disk, and therefore it is desirable that the disk has a smoother surface.

However, the smoother the surface, the easier it is for dirt and dust to stick to it.
Moreover, it tends to be difficult to remove, resulting in a problem of deterioration of durability and reliability.

C.1 Objective of the Invention An object of the present invention is to provide a magnetic disk that has excellent reliability for a long time under any environmental conditions and is highly durable.

D1 Structure of the Invention That is, the present invention provides a magnetic disk in which a disk-shaped magnetic recording medium having a magnetic layer containing magnetic powder and a binder, and a liner that can come into contact with the magnetic layer are arranged in a case. wherein the liner is formed of a nonwoven fabric having a multilayer structure, at least a portion of the nonwoven fabric that contacts the magnetic recording medium contains 30% by weight or more of rayon fiber, and hexagonal magnetic powder is included in the magnetic layer. The present invention relates to a magnetic disk characterized in that it is contained in a magnetic disk.

First, an example of a magnetic disk, such as a floppy disk, according to the present invention will be explained with reference to FIGS. 1 to 3.

FIG. 1 shows an exploded view of a small floppy disk with a center core.

In the figure, 1 is a disk-shaped magnetic recording medium, 11 is a center core, and 21 and 22 are jacket shells (cases) that rotatably house the magnetic disk and are joined together to form a floppy disk. is used.

23 is the center core fitting hole, 24.25 is the shutter hole,
26 is a shank slide, 27 is a shell 21 and 22
The shell 21 is also provided at corresponding points on the shell 21. 4 is a slide shutter, and 41 is a shutter hole.

This floppy disk has a jacket shell of 21.2
Liners 31 and 32 are pasted on each inner surface of the disc 1, the other parts of the disc 1 are housed in a predetermined position and according to specifications, and the discs 1 and 2 are point-joined using the joining protrusions 27. Furthermore, the slide shutter 4 is attached and assembled.

The liner 31.32 has a multi-layer structure (
For example, it is formed of a nonwoven fabric with a multilayer structure (eg, two layers, three layers, etc.). That is, at least the portion of this nonwoven fabric that comes into contact with the disk-shaped magnetic recording medium contains 30% by weight or more of rayon fibers.

Fig. 2 shows a liner with a three-layer structure, and the outer layer 33, 34, which is the contact part with the disk-shaped magnetic recording medium (1 in Fig. 1), contains rayon fiber in an amount of 30% by weight or more. , the cleaning performance is maintained or good, and the media is prevented from being scratched.

That is, if the rayon fiber content is less than 30% by weight, it is too small.
The cleaning action peculiar to the same fiber deteriorates, and the medium is easily damaged. Further, less than 30% by weight may contain other material components, such as acrylic, polyester, nylon, etc., which may reduce detachment of resin powder. However, the liner 31,32 according to the invention may be made of fibers other than rayon (e.g. acrylic, polyester, etc.) as the inner layer 35.
By forming the resin powder, the amount of detachment of the resin powder described above can be reduced by -i. However, a part of the inner layer 35, for example, a layer in contact with the outer layer 33, 34, is formed of a nonwoven fabric containing less than 30% by weight of rayon fibers (other than the rayon fibers may be made of acrylic, polyester, etc.), and The inner layer can be formed from fibers other than rayon.

Further, the liners 31 and 32 may have a two-layer structure, but in this case, the side in contact with the medium 1 (for example, 34 in the liner 31)
, in the liner 32, only 33) may be a nonwoven fabric layer containing 30% by weight or more of rayon fibers.

Even in the three-layer structure, only the layer 33 or 34 in contact with the medium 1 may be formed of a nonwoven fabric containing 30% by weight or more of rayon fibers.

When the liners 31 and 32 have the above three-layer structure,
It can be applied to the inner surface of the shell regardless of whether it is the front or back side.

A preferred composition of the layers 33, 34, etc. in contact with the medium 1 is one containing 60% by weight or more, more preferably 90% by weight or more of -L rayon fibers. In addition, acrylic,
Polyester, nylon, etc. can be used. The composition of the liner layer 35 that does not come into contact with the surface of the medium 1 is as follows:
Thermoplastic fibers (polyester, nylon, acrylic) are preferred, and those containing 60% by weight or more of the same resin are more preferred. As for the thickness of the liner, the thickness of the liner layer in contact with the surface of the medium is preferably 20 to 100 μm. In addition, the thickness of the entire liner is 100~,100
The thickness is preferably 150 to 300 μm, more preferably 150 to 300 μm.

Examples of the liner having the multilayer structure described above include #49-246 and SP-286 manufactured by Veeratenok.

Another important feature of the disk according to the present invention is that hexagonal magnetic powder is used as the magnetic powder.

FIG. 3 shows an example of a disk-shaped medium 1 in which magnetic layers 38 are provided on both sides of a non-magnetic support 36 with an undercoat layer 37 interposed therebetween if necessary. If necessary, an overcoat layer (not shown) may be further provided on the magnetic layer.

In such a disk-shaped medium 1, the magnetic layer 38 includes:
Since the above-mentioned hexagonal magnetic powder is used, recording and reproducing characteristics such as video output can be made good, and a high S/N ratio can also be ensured. Examples of the hexagonal magnetic powder include hexagonal ferrite 9 as shown in FIG. This hexagonal ferrite has a flat plate shape (the ratio d/l between the diameter d and the thickness t is called the plate ratio), and the axis of easy magnetization is perpendicular to the plate surface (i.e. C
axial direction), it can be easily oriented perpendicularly to ( ) by a magnetic field or mechanical orientation, making it possible to obtain a recording medium suitable for perpendicular magnetic recording.Moreover, hexagonal ferrite Short wavelengths can also be recorded efficiently.

The hexagonal ferrite magnetic material described above has the general formula: M'
O[F e 12-XMXO18] (wherein M' is a divalent metal such as Ba, Sr, or Pb.

M is In, Co-Ti, Co-V, Zn-Ge,
Zn-Nb.

At least one kind such as Zn-V metal or combination thereof represent.

X can be expressed as 3≧X≧0°). In the above, M′ is Ba, so-called B
A-ferrite magnetic powder is preferred. In addition, the grain size (diagonal length d of the plate surface) is preferably 0.01 to 0.5 μm, more preferably 0.05 to 0.3 μm, and the ferrite magnetic material of this plate is described in IEE Trans, on
It is described in detail in MAG, MAG-1816 (1982), etc.

In the present invention, the equipment and material technology used for manufacturing conventional magnetic recording media may be used.

As the binder used for the magnetic layer, abrasion-resistant polyurethane may be used. It has strong adhesion to other substances, is mechanically strong to withstand repeated stress or bending, and has good abrasion resistance and weather resistance.

Furthermore, if a cellulose resin and a vinyl chloride copolymer are also contained in addition to polyurethane, the dispersibility of the magnetic powder in the magnetic layer will be improved and its mechanical strength will be increased. However, if only the cellulose resin and the vinyl chloride copolymer are used, the layer becomes too hard, but this can be prevented by containing the above-mentioned polyurethane.

Cellulose ether, cellulose inorganic acid ester, cellulose organic acid ester, etc. can be used as the cellulose resin. The vinyl chloride copolymer described above may be partially hydrolyzed. Preferably, the vinyl chloride copolymer includes a copolymer containing vinyl chloride-vinyl acetate. Phenoxy resins can also be used. Phenoxy resin has advantages such as high mechanical strength, excellent dimensional stability (10), good heat resistance, water resistance, chemical resistance, and good adhesiveness.

These advantages are complementary to those of the polyurethane described above, and by working together, the stability of the physical properties of the magnetic layer over time can be significantly improved.

Furthermore, a modified polyurethane or a modified vinyl chloride copolymer having acidic groups (for example, sulfo group, phosphor group, carboxyl group, etc.), epoxy group, and hydroxyl group may be used as the binder resin of the two layers. These functional groups may exist in any state, but preferably form a part of the copolymer.

Furthermore, in addition to the binders described above, mixtures of thermoplastic resins, thermosetting resins, reactive resins, and electron beam curable resins may be used.

In order to improve the durability of the magnetic layer of the magnetic disk of the present invention, the magnetic paint can contain various hardening agents such as isocyanate.

Examples of aromatic isocyanates include tolylene diisocyanate (TDI) and adducts of these isocyanates with active hydrogen compounds, and those having an average molecular weight of 100 to 3,000 are suitable. Examples of the fatty acid isocyanate include hexamethylene diisocyanate (HMDI) and adducts of these isocyanates and active hydrogen compounds. Among these aliphatic isocyanates and adducts of these isocyanates and active hydrogen compounds, those having a molecular weight in the range of 100 to 3,000 are preferred. Among the aliphatic isocyanates, non-alicyclic isocyanates and adducts of these compounds with active hydrogen compounds are preferred.

A dispersant is used in the magnetic paint used to form the magnetic layer, and if necessary, a lubricant and additives such as an abrasive, a matting agent, and an antistatic agent may also be contained.

Dispersants used include lecithin, phosphate ester,
Amine compounds, alkyl sulfates, fatty acid amides,
There are higher alcohols, polyethylene oxide, sulfosuccinic acid, sulfosuccinic acid esters, (11) (12) known surfactants, and their salts. It is also possible to use salts of polymeric dispersants that have.

These dispersants may be used alone or in combination of two or more. These dispersants binder 10
It is added in an amount of 1 to 20 parts by weight per 0 parts by weight.

In addition, usable lubricants include silicone oil,
Gelaphalite, carbon black graft polymer, molybdenum disulfide, tungsten disulfide, lauric acid, myristic acid, fatty acid esters such as oleyl oleate 1 and the like can be used.

As the abrasive, commonly used materials such as fused alumina, silicon carbide, chromium oxide, corundum, artificial corundum, artificial diamond, garnet, and emery (main components: corundum and magnetite) are used. These abrasives have an average particle size of 0.05 to 5 μm, particularly preferably 0.1 to 2 μm. These abrasives are added in an amount of 1 to 20 parts by weight per 100 parts by weight of the magnetic powder. As the matting agent, organic powder or inorganic powder can be used individually or in combination. As the organic powder, acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, and phthalocyanine pigment are preferable, but polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, and polyfluoride resin powder are preferable. Ethylene resin powder can also be used, and inorganic powders include silicon oxide, titane oxide, aluminum oxide, calcium carbonate, barium sulfate, zinc oxide, tin oxide, aluminum oxide, chromium oxide, silicon carbide,
Examples include calcium carbide, α-Fez ○3, talc, kaolin, calcium sulfate, boron nitride, zinc fluoride, and molybdenum dioxide.

Antistatic agents include carbon blank, conductive powders such as graphite, tin oxide-antimony oxide compounds, titanium oxide-tin oxide-antimony oxide compounds; natural surfactants such as saponin; alkylene oxides, and glycerin. system.

(13) (14) Nonionic surfactants such as glycidol type; cationic surfactants such as higher alkylamines, quaternary ammonium salts, pyridine, other heterocycles, phosphoniums or sulfoniums; carboxylic acids, sulfonic acids ,phosphoric acid,
Examples include anionic surfactants containing acidic groups such as sulfate ester groups and phosphate ester groups; amphoteric surfactants such as amino acids, aminosulfonic acids, and sulfuric or phosphoric esters of amino alcohols.

The dry thickness of the magnetic layer is preferably 0.5 to 4.0 μm, and even more preferably 1.0 to 3.0 μm.

The range of solvents that can be added to the above paint includes: ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, propatool, and butanol; methyl acetate, ethyl acetate, butyl acetate,
Esters such as ethyl lactate and ethylene glycol monoacetate; ethers such as glycol dimethyl ether, glycol monoethyl ether, dioxane, and tetrahydrofuran; aromatic hydrocarbons such as benzene, toluene, and xylene; Halogenated hydrocarbons such as carbon, carbon tetrachloride, chloroform, and dichlorobenzene can be used.

In addition, non-magnetic supports include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate-1-, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and plastics such as polyamide and polycarbonate. The thickness of the support is 30 μm.
It is about 10 mm.

An intermediate layer (subbing layer) for improving adhesion may be provided between the support and the magnetic layer, and the intermediate layer may be formed by coating the various binders described above.

Coating methods for forming the magnetic layer on the support include air knife coating, blade coating, air knife coating, squeeze coat I, impregnation (15) (16) coating, reverse roll coating, transfer roll coating, and gravure coating. Applications include, but are not limited to, a coat, a kiss coat, a coat to coat, a spray coat, and the like.

Note that the present invention may be applied to other than the above-mentioned floppy disks, such as video floppies for electronic still cameras.

Example The present invention will be explained in detail below.

The components, proportions, order of operations, etc. shown below may be changed in various ways without departing from the spirit of the invention.

Real m2I A magnetic layer was provided according to the following magnetic coating formulation.

:Magnetic paint formulation: Co-Ti substituted Ba ferrite 100 parts by weight Carbon black 12 No.1 alumina 10 Vinyl chloride resin 20 (Nippon Zeon Co., Ltd. M)
R-110: Contains sulfonic acid metal salt) Polyurethane resin 9 (N-2304 manufactured by Nippon Polyurethane Co., Ltd.) Polyisocyanate
12 (Coronate manufactured by Nippon Polyurethane Co., Ltd.) Solid content 75% Oleyl oleate 9 Cyclohexanone 240 Methyl ethyl ketone 80 Toluene
80 This paint was dispersed in a sand mill, filtered through a 1 μm filter, coated on a support, subjected to non-orientation treatment, calender treatment, and after prescribed treatment, a magnetic disk medium was obtained.

On the other hand, a non-woven liner (#149-246 manufactured by Vellatech), which has a three-layer structure and has an outer layer of 100% by weight of rayon fibers, an inner layer of 20% by weight of nylon fibers, and 80% by weight of rayon fibers, was used. 3.5-inch floppy disk (
A microfloppy disk was created.

- Do not use liner #149-246 (5P-286 manufactured by Vellatech), whose outer layer is made of 60% rayon and 40% polyester, and whose inner layer is 100% polyester. A floppy disk was produced in the same manner as in Example 1, except for the following.

Implementation A Floppy disk was produced in the same manner as in Example 1, except that the isolated liner was not #149-246 but was replaced with a nonwoven liner whose outer layer was made of 30% by weight of rayon, 70% by weight of polyester, and whose inner layer was made of 100% by weight of polyester. Created.

Implementation A floppy disk was produced in the same manner as in Example 1, except that the isolated liner was not #149-246 but instead a nonwoven liner whose outer layer was made of 40% by weight rayon, 60% by weight polyester, and whose inner layer was 100% by weight polyester. did.

As a liner, a non-woven fabric liner made of rayon fiber and polyester fiber in a weight ratio of 50:50 is used.
A floppy disk was produced in the same manner as in Example 1 except that TK-/150 D) manufactured by Yong Co., Ltd. was used.

Comparison Side"-11 A floppy disk was produced in the same manner as in Example 1, except that a non-woven fabric liner (manufactured by Kendall Co., Ltd.: #149-303) consisting of rayon fiber and polypropylene in a weight ratio of 75:25 was used as the liner. .

This MJI Hikiknee 81 liner has an outer layer of 25% rayon and 75% polyester, and an inner layer of 100% polyester.
A floppy disk was produced in the same manner as in Example 1 using a non-woven fabric liner consisting of (19) (20).

The floppy disk samples obtained in the above Examples and Comparative Examples were each loaded into a 3.5-inch high-density floppy disk drive and recorded at 500 KHz.
Durability was investigated by measuring the running time until the playback output (measurement method is described below) reaches 60% of the initial output in a cycle thermometer at 60°C and 60°C.

Furthermore, after applying vibration for one hour using 100 of these floppy disks, the number of disks in which dropout occurred was determined, and the reliability was determined.

Further, the RF specific output power of each floppy disk was measured in the following manner. That is, a sine wave signal of 500 Kl (z was recorded and the reproduced RF output was measured.The measured reproduced RF output was
Re-'4ERF of the floppy disk manufactured in Example 1
Table 1 shows the relative values when the output is 100%. The larger the RF specific power output, the better the floppy disk.

The results are listed in Table 1 below.

(21) (λl) As seen in Table 1, the samples of the present invention exhibit excellent performance.

Functions and Effects of the Invention The present invention uses, as a liner, a nonwoven fabric having a multi-layer structure, in which at least the liner layer in contact with the surface of the medium contains 30% or more of rayon fibers. In addition, by containing hexagonal magnetic powder in the magnetic layer, high-density and high-output recording is possible, and it has excellent reliability over a wide range of temperature conditions over a long period of time. A disc with excellent durability can be obtained.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and FIG. 1 is an exploded view explaining the structure of a Fronby disk, FIG. 2 is a sectional view of a part of the liner, and FIG. 3 is a sectional view of an example of a magnetic disk medium. , FIG. 4 is an enlarged perspective view of hexagonal ferrite particles. In addition, in the symbols shown in the drawings, 1......Magnetic disk 9......Hexagonal ferrite 1-21.22
......Jaken I Shell 31.32...
・・・・・・Liner 33.34・・・・・・・・・
Outer layer 35...Inner layer 36...Support 38...Magnetic layer.

Claims (1)

[Claims] 1. A magnetic disk in which a disk-shaped magnetic recording medium having a magnetic layer containing magnetic powder and a binder and a liner that can come into contact with the magnetic layer are arranged in a case,
The liner is formed of a multi-layered nonwoven fabric,
A magnetic disk characterized in that at least a portion of the nonwoven fabric that contacts the magnetic recording medium contains 30% by weight or more of rayon fibers, and hexagonal magnetic powder is contained in the magnetic layer.