JP2826825B2 - Polishing tool - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing tool used for texturing and lapping of a magnetic disk such as a hard disk and a flexible disk.

(Prior art) A polishing tool is a conventional tool in which a polishing material powder is dispersed in a binder resin and applied to a polyethylene terephthalate (PET) film, disk, sheet, etc., and a polishing layer is formed continuously or discontinuously. Powders such as diamond, alumina, silicon carbide, iron oxide, and chromium oxide are used as abrasives.

High-precision polishing requires the use of a fine abrasive having a uniform particle size distribution. However, as the particle size of the abrasive decreases, the particles tend to agglomerate, making it difficult to uniformly disperse the abrasive in the resin. When the abrasive grains are applied in an aggregated state, the polishing object is scratched, and the polished surface of the polishing object surface becomes non-uniform, causing polishing unevenness. In particular, a textured surface of a magnetic hard disk requires a polished surface having a uniform width and depth. However, conventionally manufactured polishing tapes for hard disks have a polishing layer having a multilayer structure, and have a uniform surface structure or a Benard cell structure in which particles are in close contact with each other. However, when viewed microscopically, the surface is never uniform, and agglomerates of abrasive grains protrude from the surface of the polishing layer at many places, resulting in deep scratches or scratches.

In the case of a polishing method in which the surface structure of a polishing tape is directly transferred as a polishing surface, such as texturing of a hard disk, uniformity of the polishing surface of a polishing film is most important. However, the conventional multilayer structure and Benard
It is difficult to obtain a uniform polishing film surface with a cell structure.

(Object of the Invention) It is an object of the present invention to provide a polishing tool which has less scratches on an object to be polished and is suitable for precision polishing.

Another object of the present invention is to provide a polishing film that facilitates the control of the processing (polishing width and polishing depth) of an object to be polished, and a polishing method for a magnetic disk in which the friction with the object to be polished is small and clogging due to polishing chips is suppressed. In the supply of film.

(Summary of the Invention) The present invention uses a polishing tool in which abrasive particles are substantially uniformly dispersed and adhered in a single layer on a base (substrate) such as a polyester film, so that the abrasive used is It is possible to manufacture a polished surface having substantially only roughness according to the average particle diameter and the particle size distribution. That is, the surface polished by the polishing tool of the present invention has uniform polishing streaks without abnormal scratches.

The polishing tool of the present invention has a low surface density of the abrasive grains, and therefore a small contact area between the polishing layer and the surface to be polished. The depth of the polishing groove is increased, and the friction with the object to be polished is reduced, so that the sharpness is improved and the finished surface condition is improved.

Further, since there is a gap between the abrasive particles, the gap between the particles acts as a chip pocket, so that clogging can be prevented and the durability is improved.

In order to reduce the surface density of the abrasive grains, the abrasive grains become a single layer on a base in which the amount of the abrasive grains is dispersed at a ratio of 0.25 to 1-2 to 1 (weight ratio) with respect to the amount of the binder resin. It may be applied as thin as possible.

(Specific Description of the Invention) The present invention is characterized in that it has a structure in which abrasive particles are adhered to a substrate in a single layer and as uniformly dispersed as possible. The basic technical concept of the present invention will be described with reference to the attached drawings.

1 and 2 are a front view and a sectional view, respectively, showing a part of the polishing tool of the present invention.

In this polishing tool, a polishing layer formed by dispersing abrasive particles 2 in a binder resin 3 is applied as a substantially single layer on a base 1 such as a plastic film, a nonwoven fabric, a metal foil, a metal plate, and a glass plate. It has a structure formed. Here, a single layer means that there is substantially no superposition of particles, and preferably two or more superimposed portions of particles are 1 or less per 100 particles, more preferably 1 or less per 1000 particles, Preferably, it is reduced to 10,000 or less. As a result, the probability of occurrence of extraneous scratches (deeper and / or wider scratches) or scratches on the surface roughness of the polished surface of the object to be polished determined by the average particle size of the abrasive grains is greatly reduced, Precision polishing can be achieved. Here, a considerable number of the abrasive particles may come into contact with each other in the plane direction. What must be avoided in the present invention is that the abrasive particles overlap one another up and down to form abnormal protrusions.

Such a single-layer abrasive layer can be relatively easily formed by adjusting appropriate polymer binders, solvents, dispersants, their mixing ratios, coating means, coating amounts, etc. without using a special method. It turns out that it can be realized.

The base can be processed into an arbitrary shape such as a tape, a sheet, or a disk and used.

Examples of the abrasive include diamond, CBN, silicone carbide, single-crystal alumina, fused alumina pulverized powder, chromium oxide, iron oxide, and cerium oxide.

The abrasive preferably has a particle size of 1 μm or more. Especially 5
The effect is remarkable when particles having a size of not less than μm are used.

As the binder resin, a thermosetting resin and a thermoplastic resin can be used. As the thermosetting resin, polyester or acrylic polyol urethane resin, chlorinated polypropylene-modified acrylic polyol urethane resin, acrylic
Chelate-curable resin, epoxy or epoxy pendant acrylic resin + amine pendant acrylic resin, polyorganosiloxane resin, various UV-curable resins, urethane-based oil resin, moisture-cured polyurethane resin, fluorine resin, etc. 100 ° C or less It is suitable that the curing reaction proceeds.

As the thermoplastic resin, pure acrylic resin, vinyl chloride resin, nitrocellulose resin, nitrocellulose
Acrylic resin, modified acrylic resin, alkyd,
Polyolefin resins, polyester resins, rubber resins such as urethane elastomers, nitrile rubber, silicone rubber, ethylene vinyl acetate rubber, fluorine rubber resins, other water-soluble resins, and emulsion resins are used.

As the base film substrate, a plastic film such as polyethylene terephthalate, polyimide, polycarbonate, and a surface-treated film thereof, such as a synthetic paper, a nonwoven fabric, and a metal shell are used. Also, glass, metal, etc. can be used as a rigid substrate.

(Method of manufacturing polishing tool) After the polishing material is mixed with a binder resin and a solvent,
The coating is adjusted to an appropriate coating thickness by a suitable coating means according to the particle size distribution of the abrasive grains, and is applied to a substrate such as a film.

For example, a Meyer bar coater, a gravure coater, a reverse roll coater, a knife coater and the like can be used.

The coating thus obtained is fixed to the substrate by a drying or curing treatment.

 Next, examples of the present invention will be described.

Example 1 This example is an example in which a thermoplastic resin is used as a binder resin of a polishing layer in order to experimentally produce a polishing film according to the present invention. First, a coating liquid having a composition shown in the following table was used. Prepared.

As the abrasive grains, various kinds of meshes having different average particle diameters were adjusted by using pulverized powder WA of electrofused alumina so that the ratio of abrasive grains / resin was 1: 1. For WA2000, the effect of abrasive grain concentration was examined by changing the abrasive grain / resin concentration by three types.

A coating liquid of the composition shown in Table 1 (the numerical values are parts by weight, and V200 is a polyester resin manufactured by Toyobo Co., Ltd.) is applied by a reverse roll coater onto a 25 μm-thick polyethylene terephthalate film at an application thickness corresponding to various particle sizes. After drying the solvent, it was slit to a predetermined width, processed into a tape shape, and simultaneously polished with a nickel-plated substrate for a hard disk. The average particle size of the used abrasive powder was as follows. WA800
Is 20 μm, WA1000 is 11 μm, WA1500 is 8 μm, WA2000 is 7 μm, and WA3000 is 5 μm. The conventional high-density manufactured by the usual method using the same abrasive particles as the abrasive tape manufactured in this way. The hard disk was textured with a polishing film (hereinafter referred to as a multilayer structure type) in which abrasive grains were densely obtained by applying a binder containing abrasive grains.

Polishing with a polishing tape according to the present invention using the ordinary multilayer structure type under the conditions giving the results shown in Table 2 gave the finished surface roughness and finished surface condition shown in Table 3. In the table, the abnormal number indicates the number of scrambles of a noticeable size, and the number of scratches indicates a streak that is thicker and longer than a normal polishing streak.

 Table 4 shows the measurement results of the surface condition of the coating film of the polishing tool.

As can be seen from the results in Table 3, the polishing tool having the polishing layer having the single-layer structure of the present invention did not generate any surface scratches other than ordinary polishing streaks.

Further, when the surfaces of all the polishing tools according to this example were observed with a microscope, none of the particles that appeared to be overlapping particles were found. FIG. 3 shows an example of one manufactured in the above embodiment using WA1500. FIG. 4 shows the measured stylus profile of the surface of the same WA1500. Further, from Table 4, it can be seen that a coating film surface that can be regarded as a single layer was obtained.

Example 2 In Example 1, the binder resin was a thermosetting resin (VAGH manufactured by Union Carbide Co., Ltd.) composed of a salt having a vinyl alcohol component or a vinyl-vinyl acetate copolymer, and a curing agent (manufactured by Nippon Polyurethane Co., Ltd.) Coronate EH)
And the weight ratio P / of the abrasive grains (P) and the binder resin (R)
A coating liquid was produced by changing R as shown in Table 5, and was thermally cured to produce a polishing tape having a single-layer coating film.

When the surface roughness of the obtained coating film surface was measured by a stylus type surface roughness meter, the results shown in Table 7 were obtained. From the above results, it is possible to form a coating film which can be regarded as a substantially single layer even if the mixing ratio fluctuates. In fact, no superposition of particles was observed in the observation field by microscopic observation. Variations in the compounding ratio are not critical, and the average particle size, particle size distribution, the number of particles applied per unit area, and the like seem to be important. In general, if there is too much resin, the abrasive grains will be buried in the binder resin, so it is difficult to realize a single layer, and if there is too little binder,
The adhesive strength of the abrasive grains to the base decreases.

When the polishing operation was performed using these polishing tools, the results shown in Table 6 were obtained. However, for WA8000,
There was no particular difference from the conventional polishing tool. This is probably because the average particle size of the powder was too small. As is clear from this table, the polishing tool of the present invention has very excellent polishing characteristics.

(Operation and Effect) As described above, the following operation and effect were obtained by the present invention.

1) Since the particles are adhered to a base such as a polyethylene terephthalate film in a state where the particles are in a single layer and evenly dispersed in the resin as uniformly as possible, the abrasive film has a particle size distribution of abrasive particle diameter and a surface roughness corresponding to the shape. And the control of the shape of the work surface is facilitated.

2) Since voids between particles act as chip pockets, clogging is prevented and polishing life (durability) is improved.

3) Since the friction with the object to be polished during polishing is reduced (the contact area between the polishing film and the object to be polished is reduced), the finished surface of the polishing is good, and the fusion of the binder resin due to frictional heat can be prevented. .

4) Since the particles are present in a single layer and as independent and dispersed as possible, it is particularly economical for expensive abrasive grains such as diamond and CBN single crystal alumina.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view schematically showing a polishing tool according to the present invention, and FIG.
FIG. 3 is a cross-sectional view, FIG. 3 is a view showing a surface state of the polishing tool according to the embodiment of the present invention, and FIG. 4 is a measured pattern of the surface roughness of the polishing tool of FIG.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B25D 11/00 G11B 5/84

Claims (4)

(57) [Claims] 1. A single-layer structure in which abrasive particles are dispersed in a binder resin at a compounding weight ratio of the abrasive particles and the binder resin of 0.25: 1 to 2: 1 as particles which do not substantially overlap on the base. A polishing tool for magnetic disk texturing, wherein a polishing layer formed by bonding is formed. 2. The polishing tool for texturing a magnetic disk according to claim 1, wherein the binder resin forms a layer thinner than the average particle diameter of the abrasive particle layer. 3. The polishing tool for texturing a magnetic disk according to claim 1, wherein the abrasive particles have no more than one superposed particle per 100 particles. 4. The texturing polishing tool for a magnetic disk according to claim 1, wherein the base is selected from a film, a metal plate, a glass plate, a metal foil, and a nonwoven fabric.