JPH03176883A - 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 fatty acid ester having an unsatd. bond in the molecule 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 fatty acid ester having the unsatd. bond within the molecule. 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 fields 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, and then heating and stirrup-melting the beads and fibers to connect 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 raycon (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, since the magnetic layer of a disk-shaped medium inserted into a case comes into sliding contact with a magnetic head at high speed during recording and reproduction, the magnetic layer is required to have excellent wear resistance.

For this reason, conventionally, in the magnetic layer or on its surface,
Paraffinic hydrocarbons, which have a high point and are difficult to volatilize, coagulate into a solid or thicken at low temperatures, so they cannot exhibit a sufficient lubricating effect when used at low temperatures. On the other hand, liquids with low viscosity at low temperatures have a low boiling point and easily evaporate, or their viscosity decreases too much at high temperatures, causing excessive amounts of lubricant on the surface of the magnetic layer due to sliding contact with the object. Furthermore, even when stored at high temperatures, the lubricant oozes onto the surface of the magnetic layer, resulting in poor usability and storage stability at high temperatures. For this reason, conventional lubricants have a problem in that it is difficult to improve the wear resistance of the magnetic layer over a wide operating temperature range from low to high temperatures.

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.

21 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 and a liner capable of contacting the magnetic layer are arranged in a case, wherein the liner has a multilayer structure. The nonwoven fabric is formed of a nonwoven fabric, at least the portion of the nonwoven fabric that contacts the magnetic recording medium contains rayon fibers of 30 or more times, and the magnetic layer contains a fatty acid ester having an unsaturated bond in the molecule. The present invention relates to a magnetic disk characterized by:

First, an example of a magnetic disk according to the present invention, such as a floppy disk, 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 sliding shutter, 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 front disc has a jacket shell of 21.
A liner 31, 32 is pasted on each inner surface of the liner 31, 32, the above-mentioned disk 1 and other parts are housed in a predetermined position and according to specifications, and they are point-joined by the joining protrusion 27, and a slide shutter 4 is attached to assemble the liner 31, 32. Based on the present invention, a multilayer 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 fibers of 30% or more by weight. , 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 racon (e.g. acrylic, polyester, etc.) as the inner layer 35 .
By forming the resin powder, the detachment of the resin powder can be reduced by -layer. 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 rayon fiber fibers.

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, the side 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 three-layer structure described in -, they can be pasted on the inner surface of the shell regardless of which side is the front or back.

A preferable 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 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 to 400μ
m is good, and 150 to 300 μm is more preferable.

Examples of the liner having the above-mentioned multilayer structure include #149-246 and SP-286 manufactured by Vellatech.

Another important feature of the disk according to the present invention is that the magnetic layer contains a fatty acid ester having an unsaturated bond in the molecule.

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:
The fatty acid esters mentioned above have unsaturated bonds in their molecules, and these fatty acid esters exhibit sufficient lubricating action even at low and high temperatures, have little leaching to the surface, and can be used over a wide temperature range from low to high temperatures. The wear resistance of the magnetic layer can be maintained. This, together with the effect of the liner composition described above, contributes to maintaining the durability and reliability of the magnetic layer for a long time under any environmental conditions.

Such fatty acid esters preferably have a large molecular weight and are liquid at room temperature. Specific examples include unsaturated fatty acids such as oleic acid, erucic acid, linoleic acid, and lylunic acid, and m-alcohols having about 6 to 18 carbon atoms, or polyhydric glycols, glycerin, sorbitan, pentaerythritol, etc. Examples include esters. In addition, unsaturated alcohols such as oleyl alcohol and carbon atoms
-18 fatty acids and the like. These esters may be used alone or in combination of two or more.

The amount of the fatty acid ester used is preferably 1 to 30 parts by weight per 100 parts by weight of the magnetic powder in the magnetic layer.
More preferably 2 to 20 parts by weight. If the amount used is too small, sufficient effects will not be exhibited, while if the amount is too large, it will tend to become sticky or deteriorate the strength of the magnetic layer.

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

Examples of the magnetic material used for the magnetic layer include rF
ezCL+, Co-containing 7 Fe2 o3, C.

Adhering T Fe2 o3, Fe304, Co-containing Fe
Oxide magnetic materials such as 3O4, Co-coated Fe+04, CrO□, e.g. Fe, Ni, Fe-Ni alloy, Fe-Co
alloy, Fe-N1-P alloy, FeNi-Co alloy, Fe
-Mn-Zn alloy, FeNi-Zn alloy, Fe-Co-
Ni-Cr alloy, Fe-Co-N1-P alloy, Co-P
Alloy, C.

Examples include various ferromagnetic materials such as metal magnetic powders mainly composed of Fe, Ni, and CO such as Cr alloys. Additives to these metal magnetic materials include Si, Cu, Zn, and Af.
Elements such as fi, P, Mn, Cr, or compounds thereof may be included.

Examples of the binder used in the magnetic layer include polyurethane having wear resistance (9) (10). 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. Preferable examples of the vinyl chloride copolymer include copolymers containing vinyl chloride and vinyl acetate. Phenoxy resins can also be used. Phenoxy resin has advantages such as high mechanical strength, excellent dimensional stability, 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. 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 incyanate.

Examples of aromatic isocyanes I include tolylene diisocyanate (TDI) and adducts of these isocyanates with active hydrogen compounds, and those with an average molecular weight in the range of 100 to 3.000 (11) 12) Suitable. Examples of the fatty acid isocyanate include hexamethylene diisocyanate 1-(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 other than the lubricant (fatty acid ester) according to the present invention, an abrasive, a matting agent,
Additives such as antistatic agents may also be included.

Dispersants used include lecithin, phosphate ester,
Amine compounds, alkyl sulfates, fatty acid amides,
These include higher alcohols, polyethylene oxide, sulfosuccinic acid, sulfosuccinic acid esters, known surfactants, and salts thereof.
It is also possible to use salts of polymeric dispersants with 1-PO3H).

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.

Further, other lubricants that can be used in combination with the fatty acid ester according to the present invention include silicone oil, graphalite l-,
Carbon black graft polymer, molybdenum disulfide,
Tungsten disulfide, lauric acid, myristic acid, other fatty acid esters, etc. 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 (13) (14). As the matting agent, organic powder or inorganic powder can be used individually or in combination. As the organic powder, acrylic styrene resin powder, henzoguanamine 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, titanium oxide, aluminum oxide, calcium carbonate, barium sulfate, zinc oxide, tin oxide,
Examples include aluminum oxide, chromium oxide, silicon carbide, calcium carbide, α-Fe203, talc, kaolin, calcium sulfate, boron nitride, zinc fluoride, and molybdenum dioxide.

Antistatic agents include carbon black, conductive powders such as graphite, tin oxide-antimony oxide compounds, titanium oxide-tin oxide-antimony oxide compounds; natural surfactants such as saponin; alkylene oxides, glycerin. Cationic surfactants such as higher alkylamines, quaternary ammonium salts, pyridine, other heterocycles, phosphonium or sulfoniums; Carboxylic acids, sulfonic acids, phosphoric acids, sulfuric acids Examples include anionic surfactants containing acidic groups such as ester groups and phosphoric 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 xy(15) (16); methylene chloride; Halogenated hydrocarbons such as ethylene chloride, carbon tetrachloride, chloroform, and dichlorobenzene can be used.

Examples of non-magnetic supports include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, 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 coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, and cast coating. Coating agent 1~, spray coating, etc. can be used, but are not limited to these.

Note that the present invention may be applied to other than the above-mentioned floppy disk, such as a video floppy for an electronic still camera.

E, 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.

Actual picture 1 A magnetic layer was provided according to the following magnetic coating formulation.

: Magnetic paint formulation: Co-containing α 3100 parts by weight of FezO Carbon black 12 Horn alumina 10 Horn vinyl chloride resin 20 (manufactured by Nippon Zeon Co., Ltd. MR-110: Contains sulfonic acid metal salt) (17) (18) Polyurethane resin 9 (Japan Polyurethane) N-2304) Polyisocyanate
12〃(Coronate L 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 Kendo mill, filtered through a 1 μm filter, coated on a support, subjected to non-orientation treatment, calender treatment, and after predetermined treatment, it was used as a magnetic disk medium.

On the other hand, a non-woven liner (#149 to 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 at 3.5%. 3.5 inch floppy disk (micro floppy disk)
was created.

A floppy disk was prepared in the same manner as in Example 1 except that the same amount of lauryl oleate was used in place of oleyl oleate I.

Jutsu 1st Edition 1 A floppy disk was produced in the same manner as in Example 1 except that the same amount of glycerin triolate was used in place of oleyl oleate.

Example t A floppy disk was produced in the same manner as in Example 1, except that the same amount of oleyl isostearate was used in place of oleyl oleate.

A floppy disk was produced in the same manner as in Example 1, except that the same amount of butyl stearate was used in place of fluoroyl oleate.

SUu'J 5 The liner is not #149-246, the outer layer is 60% by weight rayon, 40% by weight polyester, the inner layer (19% by weight)
) (20) A floppy disk was produced in the same manner as in Example 1, except that (20) was replaced with a nonwoven fabric liner (Sl"-286, manufactured by Vellatech) made of 100% by weight polyester.

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.

A floppy disk was produced in the same manner as in Example 1, except that the outer layer was made of 40% rayon, 60% polyester, and the inner layer was 100% polyester, instead of #149-246. Created.

JjJJJl12 As a liner, a nonwoven fabric liner (= rhombus) 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 a floppy disk (TK-450D manufactured by Yong Co., Ltd.) was used.

Kitamoto L [Ll Engineering Y A floppy disk was produced in the same manner as in Example 1, except that a non-woven 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. did.

This 51 [0 (outdoor layer part is 25% by weight of rayon, 75% by weight of polyester)
A floppy disk was produced in the same manner as in Example 1 using a nonwoven fabric liner whose inner layer was made of 100% by weight polyester.

The same amount of butyl stearate is used in place of Oleyl Ole 1, and the outer layer is 25% by weight of rayon as a liner.
, 75% polyester by weight, inner layer 10% polyester
A floppy disk was produced in the same manner as in Example 1 using a nonwoven fabric liner containing 0% by weight.

The floppy (2I) (22) -disk samples obtained in the above Examples and Comparative Examples were loaded into a 3.5-inch high-density floppy disk drive and heated at 250 Kl (recording was performed at z, 5° Measure the running time until the playback output reaches 60% of the initial output in a cycle thermometer at 60°C and 60°C.
We investigated durability.

Using 100 discs, the number of discs in which dropout occurred after applying vibration for one hour was determined, and the reliability was determined.

The results are listed in Table 1 below.

(Margin below) As seen in Table 1, The results show excellent performance.

1. Effects of the Invention As described above, the sample of the present invention is an excellent liner. By using a magnetic layer that contains
The result is a disk that is error-free and extremely durable under a wide range of temperature conditions.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and FIG. 1 is an exploded view illustrating the structure of a floppy disk, FIG. 2 is a sectional view of a portion of a liner, and FIG. 3 is a sectional view of an example of a magnetic disk medium. be. In addition, in the symbols shown in the drawings, 1......Magnetic disk 21.22......Jacket shell 31.
32・・・・・・Liner 33.34・・・・・・
. . . Outer layer 35 . . . Inner layer (24) 36 . . . Support 38 . . . Magnetic layer.

Claims (1)

[Claims] 1. In a magnetic disk in which a disk-shaped magnetic recording medium having a magnetic layer and a liner capable of contacting the magnetic layer are disposed in a case, the liner is formed of a nonwoven fabric with a multilayer structure, and the liner is made of a nonwoven fabric with a multilayer structure. A magnetic disk characterized in that at least the portion in contact with the magnetic recording medium contains 30% by weight or more of rayon fiber, and the magnetic layer contains a fatty acid ester having an unsaturated bond in the molecule.