JPH04141377A - Surface polishing tape and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium of uniform quality continuously without changing the setting of a polishing condition by forming the polishing layer surface in such a way that the grain diameter of abrasive grain is larger at the winding beginning of a tape than at the winding end. CONSTITUTION:Two kinds of abrasive grain of different diameter are applied onto a supporting body 5 by a coating machine 4 while changing the mixing ratio of the large diameter abrasive grain in a tank 2 to the small diameter abrasive grain in a tank 1 in such a way as to be smaller toward the winding end of a tape from the beginning of winding. As a result, a surface polishing tape of uniform roughness can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium used to ensure the smoothness of the surface of the magnetic recording medium when manufacturing magnetic recording media such as flexible magnetic disks and magnetic tapes. The present invention relates to a surface polishing tape roll and a manufacturing method thereof.

[Prior Art] In recent years, there has been an increasing demand for higher densities in magnetic recording media such as flexible magnetic disks and magnetic tapes, and for this reason, it is desired to develop design techniques for ultra-smooth media. As a means of achieving this ultra-smooth medium, a method of polishing the surface of a magnetic recording medium using a polishing tape has been adopted. Generally, this polishing material for the surface of magnetic recording media is made by mixing and dispersing abrasive particles and a binder as main components and various additives including a dispersant using a dispersing machine such as a pole mill. It is obtained by uniformly coating a substrate such as a film. The surface of the magnetic recording medium is polished by using this surface polishing tape to remove minute protrusions present on the surface of the magnetic layer.

[Problems to be Solved by the Invention] In general, single-surface polishing tapes are coated with a polishing layer on a long support serving as a substrate, dried, wound around a single frame, and then slit to a predetermined width. If a binder is added, a curing treatment is performed in a constant temperature bath to harden the binder and the wire is wound. The surface polishing tape is usually supplied in a roll-like form wound in one roll, but due to the tightening of five rolls, the part at the beginning of winding on the reel is different from the end part (i.e., the outer circumferential part) on the reel. When strong pressure is applied to the tape on the inner circumference (that is, on the inner circumference) and a curing process is performed, the abrasive particles on the inner circumference penetrate into the abrasive layer and the surface roughness decreases, as shown in Figure 5. As a result, the polishing ability deteriorated. Further, even when the curing treatment is not performed, since the polishing layer is soft, the polishing particles sink into the polishing layer at the inner peripheral portion, resulting in a decrease in roughness due to tightening. For example, when polishing the surface of a flexible magnetic disk using such a surface polishing tape, the first part of the surface polishing tape (
Because the polishing ability of the end-of-use part (inner part) is inferior to that of the outer part (outer part), when producing flexible magnetic disks of a certain quality in succession, polishing should be done according to the part where the 9-surface polishing tape is used. I had to adjust my time. This has caused a major problem in that the production efficiency of flexible magnetic disks has decreased significantly.

Therefore, one technical problem of the present invention is to provide a long surface polishing tape wound into a roll whose surface roughness is made constant in the longitudinal direction of the tape.

Furthermore, another technical problem of the present invention is to provide a method for manufacturing a surface polishing tape that can efficiently produce a magnetic recording medium having a certain quality when polishing is performed using the above-mentioned surface polishing tape. It is about providing.

[Means for Solving the Problems] According to the present invention, a polishing layer comprising an elongated support and a polishing layer containing polishing particles and a binder formed on the support.
In the surface polishing tape roll wound around the reel,
A wound tape body for surface polishing is obtained, wherein the surface of the polishing layer is formed such that the particle size of the polishing particles is larger at the beginning of winding of the tape than at the end of winding.

According to the present invention, in the method for manufacturing a tape roll for surface polishing in which a paste containing abrasive particles is applied and wound onto a long support, two types of tape having different particle sizes are used as the abrasive particles. The tape is coated on the support while changing the mixing ratio of large-sized abrasive particles and small-sized abrasive particles from the beginning of winding to the end of winding. A method for manufacturing a surface polishing tape is obtained.

Examples of the support used in the present invention include polyethylene terephthalate, polyacetate, polyimide, etc., and any of them may be used.

On the other hand, the abrasive particles used in the present invention have a Mohs hardness of 6
Fine powders of molten alumina, silicon carbide,
Chromium oxide 2 α-iron oxide, diamond, silicon oxide,
Examples include titanium oxide.

The average particle diameter of this fine powder may be in the range of 0.01 to 10 .mu.m, preferably 0.3 to 3 .mu.m.

Furthermore, in the present invention, conventionally commercially available resins can be used as the binder for the abrasive particles contained in the paste. For example, vinyl monochloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl propionate copolymer, vinyl chloride-acrylic acid ester copolymer,
Examples include vinyl chloride-vinyl acetate-maleic acid copolymer, polyvinyl butyral resin, acrylonitrile-butadiene copolymer, epoxy resin, phenoxy resin, urethane resin, and the like. These resins may be used alone or in combination of one or more resins.

Furthermore, in the present invention, examples of dispersants for abrasive particles contained in the paste include alkyl betaine compounds, alkyl phosphate esters, higher fatty acids having 12 to 18 carbon atoms, and alkali metal salts thereof. The amount of this dispersant added may be within the range of O1j to 10 wt%, preferably 1 to 3 wt%, based on the abrasive particles.

[Function] In the present invention, a roughness gradient is provided in the longitudinal direction of the first surface polishing tape, so even if a roughness gradient occurs due to tightening during the curing process, it is canceled by the roughness gradient set in advance. As a result, it is possible to obtain a surface abrasive tape with uniform roughness. Therefore, by polishing a magnetic recording medium using the surface polishing tape according to the present invention, it is no longer necessary to control the polishing time, and production efficiency can be improved.

[Example] An example according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method for manufacturing a surface polishing tape according to the present invention. In FIG. 1, there is a storage tank 11 for supplying paint A in which small-sized abrasive particles, a binder, and a dispersant are mixed and dispersed to a mixing tank 3; A storage tank 2 for supplying paint B in which a binder and a dispersant are mixed and dispersed to a mixing tank 3. It is comprised of a mixing tank 3 for mixing and dispersing paint A and paint B, and a coating machine 4 for applying a paste of the mixed paint onto a support. The supply amounts of paint A and paint B supplied to the mixing tank 3 are adjusted by paint supply pumps 1a and 2a attached to the storage tank 1 and the storage tank 2. Further, the paste is supplied from the mixing tank 3 to the coating machine 4 by a paint supply pump 3a attached to the mixing tank 3. The coating machine 4 includes an unwinding and coater head section, a dryer 4b,
and a winding portion 4c.

Figure 2 shows paint A in the surface polishing tape manufacturing equipment shown in Figure 1.
and FIG. 6 is a diagram showing changes over time in the supply amount of paint B. Second
In the figure, the application of the paste to the support takes place from time t1 to time t2. In other words, most of the abrasive particles in the paste at 2 hours t are smaller of the two types of abrasive particles, but as 1 hour passes, the amount of larger abrasive particles supplied increases. Therefore, the particle size distribution of the abrasive particles in the paste shifts in the larger direction. With the particle size distribution changing in this way, the paste is applied to the support using the coating machine 4 shown in FIG. 1. The coating method used by the coating machine used here may be any method.

The simplest method is, for example, the gravure coating method.

When using the gravure coating method, as shown in Figure 1,
The support 5 wound around the reel 46a of the coating machine 4 is unwound and coated in the coater head section 4a, guided by guide rollers, and dried by the dryer 4b provided in the coating machine 4 to form one roll. At the take-up portion 4c, it is wound up into a roll on the winding frame 4],c. Furthermore, the surface polishing tape after application and drying is slit into a width of 1 inch and re-wound onto another roll. Reference numeral 6 in the figure indicates the moving direction of the tape, 41a, 42a.

42c, 43a, and 44a indicate guide rollers, respectively.

The surface polishing tape prepared by the above procedure has many small abrasive particles distributed at the end of the winding (i.e., the outer periphery) and a large number of large abrasive particles at the beginning of the first winding (i.e., the inner periphery).

Further, the surface polishing tape obtained by the above procedure was heated at 65° C. while being wound into a roll.

A curing treatment was performed for 72 hours.

In order to compare the surface polishing tape according to the present invention with a conventionally used surface polishing tape, a performance test was conducted between a sample obtained by carrying out the present invention and a comparative sample obtained by a conventional method.

Below, remaining white No. table After kneading the composition shown in Table 1 in a ball mill for 50 hours.

4 parts by weight (solid content) of an isocyanate compound (Coronate L manufactured by Nippon Polyurethane Co., Ltd.) was added and kneaded for an additional hour to obtain paint A and paint B. Furthermore, paint A and paint B were mixed in a mixing tank to form a paste, and this was coated onto a 50 μM thick polyester film using a gravure roll so that the thickness of the polishing layer after drying was 15 μm. After drying and slitting into 1 inch wide pieces.

The sample was cured at 65°C for 72 hours.

(Comparative example) When forming the polishing layer in Example 1, Example 1 was used except that only one type of molten alumina was used with an average particle size of 0.5 μm.
A sample was obtained in the same manner.

The time required for polishing when polishing the surface of a flexible magnetic disk using each of the surface polishing tapes prepared in Example 1 and Comparative Example 1 above is 20% higher than that of the unpolished product. Each tape position was investigated when the surface polishing tape roll was divided into five equal parts from the vicinity of the outermost circumference to the vicinity of the innermost circumference.

FIG. 3 shows the results for the surface polishing tape wound body obtained in the example of the present invention.

Further, the results for the surface polishing tape wound body obtained in the comparative example are shown in FIG.

The polishing time of the surface polishing tape roll in the embodiment shown in FIG. 3 does not change from the outermost circumference to the innermost circumference, but in the comparative example shown in FIG. 4, the polishing time increases as it moves toward the innermost circumference. It was found that the polishing conditions gradually became longer, making it difficult to set the polishing conditions.

[Effects of the Invention] As described above, if the surface polishing tape roll and the method for manufacturing the surface polishing tape roll according to the present invention are used,
A surface polishing tape roll having uniform roughness from the outer circumference (i.e., the end of winding) to the inner circumference (i.e., the beginning of winding) of the long surface polishing tape roll is obtained, and the surface polishing tape is By using a wound body, it is possible to continuously produce magnetic recording media of uniform quality without changing the setting of polishing conditions, thereby improving the production efficiency of the magnetic recording media.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the method of manufacturing a tape wound body for polishing the surface of a magnetic recording medium according to the present invention, and FIG.
The figure shows the change over time in the supply amount of paint A and paint B in the apparatus of Figure 1, and Figure 3 shows the polishing ability of each part of the tape roll for polishing the surface of a magnetic recording medium according to the embodiment of the present invention. FIG. 4 is a diagram showing changes in polishing ability in each part of a magnetic recording medium surface polishing tape roll according to a comparative example of the present invention, and FIG. 5 is a diagram showing a conventional surface polishing tape used in the present invention. It is a figure showing the surface roughness of each part. In the figure, 1... Storage tank for supplying paint A. 1a...Paint A supply pump, 2...Storage tank for supplying paint B, 2a...Paint B supply pump, 3...
・Mixing tank for mixing and dispersing paint A and paint B, 3a...pump for supplying mixed paint paste,
4... Grass for coating the polishing layer on the support] 4 Via coating machine. a... Unwinding and coater head section. b... Dryer C... Winding section. Peng

Claims (1)

[Scope of Claims] 1. A surface polishing product having a long support and a polishing layer formed on the support containing abrasive particles and a binder, and wound around a reel for surface polishing. In a tape roll. The surface of the polishing layer is formed such that the particle size of the polishing particles is larger at the beginning of winding of the tape than at the end of winding. 2. A method for manufacturing a tape roll for surface polishing in which a paste containing abrasive particles is applied and wound onto a long support, in which two types of tape having different particle sizes are used as the abrasive particles, and the tape is wound. Surface polishing characterized in that the coating is applied on the support while changing the mixing ratio of abrasive particles with a large particle size and abrasive particles with a small particle size from large to small from the beginning to the end of winding. method for manufacturing tape for use.