JPH0740425B2 - Floppy disk - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a floppy disk comprising a magnetic disk medium having a magnetic layer provided on a disk-shaped non-magnetic support, and a jacket enclosing the magnetic disk medium.

[Prior Art] Generally, in a jacket of a floppy disk, dust entering from an opening or the like for slidingly contacting a magnetic disk medium and a magnetic head encased in the jacket or abrasion powder generated due to the sliding contact is magnetic. In order to prevent it from adhering to the magnetic layer surface of the disk medium and deteriorating the electromagnetic conversion characteristics, a liner made of non-woven fabric is provided on the inner surface so that it can come into contact with the magnetic layer, and the dust and abrasion powder are wiped off with the liner Is configured. As such a liner, a non-woven fabric in which spherical spherical beads of polypropylene are mixed with rayon long fibers and the beads are heated and melted to connect the rayon long fibers to each other has been generally used.

On the other hand, the magnetic disk medium loaded in the jacket is required to have excellent durability because its magnetic layer makes sliding contact with the magnetic head at a very large relative speed during recording and reproduction.
Therefore, conventionally, it has been a general practice to include fluid paraffin as a lubricant in the magnetic layer. That is, this fluidized paraffin is leached from the magnetic layer, and most of it is transferred and impregnated into the liner of the jacket, and is continuously replenished to the surface of the magnetic layer which is in sliding contact with the magnetic head under the use of the floppy disk, and the sliding contact interface. It has the function of improving the durability by reducing the coefficient of friction of (unknown in the literature).

[Problems to be solved by the invention]

However, in recent years, there has been a tendency to reduce the thickness of the magnetic layer of the magnetic disk medium in order to increase the recording density of the floppy disk, and as a result, the amount of lubricant that can be contained in the magnetic layer also decreases. The fluid paraffin, which is a general-purpose lubricant, has a problem that sufficient durability cannot be obtained.

Therefore, as a result of intensive investigations by the present inventors on a lubricant that can provide sufficient durability even when the thickness of the magnetic layer is reduced to achieve high recording density, unsaturated fatty acid ester is extremely effective. I found a thing. However,
The floppy disk in which the magnetic disk medium provided with the magnetic layer containing the unsaturated fatty acid ester is loaded into the jacket provided with the conventional liner described above has a serious drawback that dropouts occur very often. There was found.

Therefore, the present invention solves the above-mentioned drawbacks when an unsaturated fatty acid ester is used as a lubricant, and is excellent in durability even if the magnetic layer of the magnetic disk medium is thinned for higher recording density. Moreover, it aims to provide a floppy disc with few dropouts.

[Means for solving problems]

The inventors of the present invention have made extensive studies on the cause of the dropout based on the comparison between the case where the lubricant is a conventional general-purpose fluid paraffin and the case where the lubricant is an unsaturated fatty acid ester, and as a result, the following findings have been obtained.

That is, the non-woven fabric used for the liner of this type of jacket is embossed with a concavo-convex pattern such that each vertex of the surface is deformed when the fibers are partially heat-sealed in the production. A non-woven fabric raw material is heated and pressed between hot rolls, and the heat-fusible material that is in contact with the convex portions of the concavo-convex pattern is melted to form a liner for a floppy disc. In this case, in the liner of the conventional structure, a part of the spherical polypropylene beads mixed as the heat-fusible material is melted by the contact of the heat roll and participates in the interconnection of the rayon filaments. There are also some polypropylene spherical beads in the liner that are not involved in the process and therefore easily fall off the liner.

However, when the lubricant contained in the magnetic layer of the magnetic disc member is a conventional general-purpose fluid paraffin, the fluid paraffin transferred from the magnetic layer and impregnated and retained in the liner and the polypropylene of the spherical beads are both hydrocarbons. Due to the fact that they have a good affinity, these spherical beads are less likely to fall off the liner. Further, even if these spherical beads fall off on the surface of the magnetic layer, since the magnetic layer is not plasticized by the fluid paraffin and has low surface tackiness, sliding contact between the magnetic layer and the liner during use It is easily wiped again on the liner side. Therefore,
In the above conventional structure, the dropout caused by the spherical beads hardly causes a problem.

On the other hand, when the lubricant is an unsaturated fatty acid ester, the spherical beads polypropylene has a poor affinity with the unsaturated fatty acid ester, and therefore these spherical beads easily fall off from the liner, and the magnetic layer has an unsaturated fatty acid ester. Since it has a good affinity with, it is plasticized and has a tacky surface, and thus it is difficult for the liner to wipe off the spherical beads that have fallen off on the surface of the magnetic layer. Moreover, the spherical beads having a high hardness of polypropylene of these spherical beads and involved in the heat fusion of the non-woven fabric are deformed into a claw shape by contact with the convex portion of the heat roll when observed microscopically, In addition, since the magnetic layer is softened by the plasticization, the magnetic layer is easily scraped by the beads to generate abrasion powder, and the powder has a poor affinity with polypropylene of the liner and is magnetic. As the layer surface is sticky, it is also difficult to wipe off with a liner. Therefore, when unsaturated fatty acid ester is used as a lubricant, the durability of the floppy disc is improved, but on the other hand, spherical beads remaining on the surface of the magnetic layer that are not wiped off and dropouts caused by abrasion powder of the magnetic layer are generated. It becomes a big problem.

Therefore, as a result of further research to prevent the dropout, the present inventors have found that when an unsaturated fatty acid ester is used as a lubricant, it contains a specific fiber as a liner of a jacket and uses this fiber as described above. When a heat-bonded non-woven fabric is used instead of the spherical beads, the dropout is almost completely prevented, and in addition, the high lubrication effect of the unsaturated fatty acid ester is effectively exhibited over a long period of time. As a result, they have found that the durability itself is further improved, and have made the present invention.

That is, the present invention is a floppy disc comprising a magnetic disk medium having a magnetic layer provided on a disk-shaped non-magnetic support, and a jacket which encloses the magnetic disk medium and has a liner on the inner surface of which can contact the surface of the magnetic layer. In the disk, there is provided a floppy disc, wherein the unsaturated fatty acid ester is contained on the surface of the magnetic layer, and the liner contains a polyester fiber and is made of a non-woven fabric fused by partial melting of the fiber.

[Constitution / Operation of Invention]

The structure of the floppy disc of the present invention is the same as that conventionally known. For example, as shown in FIG. 1, a non-magnetic support 1a made of polyester film or the like is used.
It is composed of a magnetic disk medium 1 having magnetic layers 2 and 2 provided on both sides thereof, and a jacket 3 enclosing the magnetic disk medium. Liners 4 and 4 made of a non-woven fabric are provided on the inner surface of the jacket 3 on the entire surfaces facing each magnetic layer 2. It is attached. As shown in FIG. 2, the jacket 3 is provided with rectangular openings 5 on both sides at one place for sliding contact between the magnetic head and the magnetic layer 2. The jacket 3 includes a soft jacket made of a soft vinyl chloride resin or the like and a hard jacket made of various hard synthetic resins.

One of the features of the present invention is that the magnetic layers 2, 2 of the magnetic disk medium 1 contain unsaturated fatty acid ester as a lubricant. This unsaturated fatty acid ester generally maintains a liquid state in a wide temperature range, and by having an appropriate amount on the surface of the magnetic layer, it exhibits excellent fluid lubricity at the sliding contact interface between the magnetic head and the magnetic layer. The wear resistance of the magnetic layer is greatly improved, and as a result, the durability of the floppy disk is significantly improved. And this lubricity is, as is clear from the comparison between the example and the comparative example described later, is significantly superior to the conventional general-purpose fluid paraffin, and compared to the saturated fatty acid ester which is usually solid. Since it is significantly good, sufficient durability can be obtained even when the thickness of the magnetic layer 2 is reduced for the purpose of high density recording.

Needless to say, the unsaturated fatty acid ester is required to be liquid at room temperature, but from the viewpoint of suppressing the consumption due to volatilization and maintaining the lubricating effect for a long period, one having a high boiling point, that is, a large molecular weight, particularly carbon Number
Those of 26 or more are preferable. Specific examples of such unsaturated fatty acid esters include unsaturated fatty acid components such as oleic acid, linoleic acid, and linolenic acid (which may contain saturated fatty acids as part of them), and 8 to 18 carbon atoms.
Esters with a degree of alcohol are preferred.

The amount of the unsaturated fatty acid ester used is preferably about 1.0 to 40.0 parts by weight with respect to 100 parts by weight of the magnetic powder mixed in the magnetic layer. The surface of the layer becomes sticky and dust easily attaches, and the distance between the magnetic head and the surface of the magnetic layer is widened.
That is, the output is reduced due to spacing loss.

The magnetic disk medium may be manufactured according to a conventional method. For example, a magnetic paint containing a magnetic powder, a binder, an organic solvent and, if necessary, various additives is applied to the surface of a non-magnetic support such as polyester film. A method is employed in which a magnetic layer is formed by drying and calendering and then punched into a disk having a predetermined size.

As the magnetic powder, γ-Fe ₂ O ₃ , Fe ₃ O ₄ , Co-containing γ-Fe
₂ O ₃ , Co-containing Fe ₃ O ₄ , CrO ₂ , Ba, Sr, Pb oxide magnetic powder such as ferrite, Fe, Ni, Co, alloys of these or other metals or small amounts of non-metal elements Any magnetic metal powder such as an alloy can be used. Further, as the binder, vinyl chloride-vinyl acetate-based copolymer, fiber-based resin, polyvinyl butyral, polyester-based resin, polyurethane, epoxy-based resin, polyol and polyisocyanate compound as a cross-linking agent, etc. Any of the known binders for the magnetic layer can be used. In addition, additives that are added as necessary include a dispersant, an abrasive, an antistatic agent, and the like.

The thickness of the magnetic layer is not particularly limited, but the application effect of the present invention is great when the thickness is about 0.5 to 2.0 μm (one side) for high density recording.

The feature of the present invention is to use an unsaturated fatty acid ester as a lubricant as in the above technique, and to use a non-woven fabric containing polyester fibers as a liner provided on the inner surface of a jacket and fused by partial melting of the fibers. There is a point to use. That is, in the jacket liner of the present invention, since the heat-fusible material is polyester fiber, polypropylene spherical beads that do not participate in heat-fusion, such as the liner of the conventional structure, do not fall off, and this polyester Since the fiber is softer in terms of material and softer in shape than polypropylene of the spherical beads, it may be scraped off even though the magnetic layer is softened by being plasticized with unsaturated polyester. There is no. Therefore, the generation of granular or powdery substances causing dropout from the liner and the magnetic layer is almost completely eliminated. In addition, since the polyester fiber and the unsaturated fatty acid ester as a lubricant have a good affinity, the impregnation retention force of the unsaturated fatty acid ester by the liner is large, and the unsaturated fatty acid ester is less likely to escape and its high lubricating effect is obtained. As a result of being exerted over a long period of time, the durability of the floppy disc becomes better than that when using a liner of other constitution.

As the non-woven fabric used for such a liner, the entire fibrous material may be polyester fibers, or may be a mixed spinning of polyester fibers and other fibers such as rayon fibers. In the latter mixed spinning, it is recommended that 30% by weight or more of the total fibers be polyester fibers, from the viewpoint of ensuring sufficient heat fusion of the nonwoven fabric.

To prepare the liner used in the present invention, for example, as in the conventional one described above, the above nonwoven fabric material is passed through an embossing hot roll having an uneven pattern on its surface,
A part of the polyester fibers in the above material may be melted to partially bond the fibers to each other, and then the fibers may be cut into an appropriate size and attached to the inner surface of the jacket. In addition,
Since the polyester fiber is a material excellent in heat fusion property, it can be fused at a lower heating temperature as compared with the conventional one using polypropylene beads and the like.

Incidentally, the contact between the liner and the magnetic layer in the Froppy disc prepared by loading the magnetic disc medium in the jacket, when the jacket is a soft jacket, when the floppy disc is mounted on the recording / reproducing apparatus. Generally, for example, as shown by the alternate long and short dash line in FIG. 2, the pressure plate 6 is automatically pressed from both sides for the purpose of preventing flapping during use and cleaning, so that at this pressing position. Definitely done. When the jacket is a hard jacket, for example, as shown in FIG. 3, the inner surface of one side of the jacket 3 and the liner 4 are covered.
An elastic body 7 made of a hard synthetic resin film piece bent in a substantially V-shape is interposed in a portion between and, and a bulging portion 3a such as a parallel protrusion is provided on the inner surface of the jacket 3 facing the elastic body 7. The structure in which the magnetic layers 2, 2 on both sides and the liners 4, 4 are brought into contact with each other by the pressing force of the elastic body 7 is adopted. The bulge 3
Instead of providing a, a similar elastic body 7 may be provided in this portion.

〔The invention's effect〕

The floppy disc of the present invention comprises an unsaturated fatty acid ester on the surface of the magnetic layer of the magnetic disc medium, and the liner of the jacket is made of a non-woven fabric containing polyester fibers and fused by partial melting of the fibers. Therefore, the durability is extremely good due to the excellent lubricating effect of the unsaturated fatty acid ester and the high impregnation holding force of the liner, and even if the thickness of the magnetic layer is reduced for the purpose of high density recording, etc. Sufficient durability is obtained, and the dropout which cannot be avoided when the above-mentioned magnetic disk medium and a conventional jacket having a liner using polypropylene spherical beads as a heat-sealing material are combined is almost completely avoided. It will be prevented.

〔Example〕

Hereinafter, examples of the present invention will be specifically described in comparison with comparative examples. In the following, "parts" means "parts by weight".

Example 1 Co-containing γ-Fe ₂ O ₃ 1,000 parts Carbon black (antistatic agent) 150 parts α-Fe ₂ O ₃ (abrasive) 100 parts Oleyl oleate 120 parts Nitrocellulose (trade name RS1 manufactured by Daicel) 156 parts Polyurethane (trade name HI2000 manufactured by Dainippon Ink and Chemicals) 156
Part Polyisocyanate compound 78 parts Cyclohexanone 2,000 parts Toluene 2,000 parts A magnetic coating composition of the above composition was prepared and the thickness was 75 μm.
Each surface of the polyethylene terephthalate film was dried and coated so as to have a thickness of 1.3 μm after calendering, and then calendered, punched into a disk shape, and polished to prepare a magnetic disk medium.

On the other hand, the weight ratio of rayon fiber to polyester fiber is 50: 5.
A liner made of non-woven fabric that was mixed-spun at 0 and heat-sealed by partial melting of this polyester fiber (Kendall's trade name # 149-188) was attached to both inner surface sides of a soft vinyl chloride soft jacket. Then, the magnetic disk medium was loaded into the jacket to produce a floppy disk.

Example 2 A floppy disc was prepared in the same manner as in Example 1 except that the same amount of octyl oleate was used instead of oleyl oleate.

Example 3 A frothpie disk was produced in the same manner as in Example 1 except that a non-woven fabric (trade name # 149-077 manufactured by Kendall Co., Ltd.), which was made of only polyester fibers and partially melted as a liner, was used as the liner. did.

Comparative Example 1 A floppy disc was prepared in the same manner as in Example 1 except that 120 parts of fluid paraffin was used instead of oleyl oleate.

Comparative Example 2 A floppy disc was prepared in the same manner as in Example 1 except that 120 parts of butyl stearate was used instead of oleyl oleate.

Comparative Example 3 Implemented except that a non-woven fabric (trade name # 149-029 manufactured by Kendall Co., Ltd.) was used as a liner, in which rayon fibers were mixed with spherical polypropylene beads and part of the spherical beads were melted and heat-bonded. A floppy disc was prepared in the same manner as in Example 1.

Each of the floppy discs obtained in the above examples and comparative examples was mounted in a 5-inch high-density floppy disc drive, and recording was performed at 250 KHz, and the running output was 70% of the initial output. The time was measured and the durability was examined. Using 100 of each of these floppy discs, the number of floppy discs in which a read / write error occurred was determined by 1,000-hour random seek, and the result was used as the dropout characteristic. The results of both tests are shown in the table below.
The durability was measured on the magnetic layers on both sides of the disk medium, and the one having shorter running time was taken and shown in the table below.

As is clear from the above table, the floppy discs (Examples 1 to 3) of the present invention have extremely good durability and excellent reliability without dropout.
The one using a conventional general-purpose fluid paraffin as a lubricant (Comparative Example 1) and the one using a saturated fatty acid ester (Comparative Example 2) are extremely inferior in durability, and an unsaturated fatty acid ester is used as a lubricant and It can be seen that the one using a non-woven fabric thermally fused with polypropylene spherical beads as a liner (Comparative Example 3) is excellent in durability but is likely to cause dropout.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a floppy disk, FIG. 2 is a plan view of the floppy disk, and FIG. 3 is a sectional view of an essential part of a floppy disk using a hard jacket. 1 ... Magnetic disk medium, 1a ... Non-magnetic support, 2, 2 ...
... magnetic layer, 3 ... jacket, 4,4 ... liner

Claims (1)

[Claims] 1. A floppy disk comprising a magnetic disk medium having a magnetic layer provided on a disk-shaped non-magnetic support, and a jacket having the magnetic layer and a liner having an inner surface for contacting the surface of the magnetic layer. 2. A floppy disc, wherein the surface of the magnetic layer contains an unsaturated fatty acid ester, and the liner contains a polyester fiber and is made of a non-woven fabric fused by partial melting of the fiber.