JPH06278037A - Abrasive film used for texturing magnetic disk - Google Patents

Abstract

PURPOSE:To restrain the influence of large grains so as to form a surface that is machined at high accuracy to meet high recording density by sequentially laminating an intermediate layer comprising spherical grains dispersed in a soft resin and an abrasive layer on a base into an abrasive film. CONSTITUTION:Spherical grains of acrylic styrene resin having an average diameter of 0.4 to 25mum, a benzoguanamine-formaldehyde condensate or a nylon resin, etc., are dispersed in a solvent, together with a binder resin, to prepare a liquid for application as an intermediate layer. An abrasive material, selected from alumina having an average diameter of 2 to 4mum, silicon carbide and diamond, is dispersed in a solvent, together with a binder resin, to prepare a liquid for application for an abrasive layer. The liquid for application for an intermediate layer is applied to a base such as a polyethylene terephtalate, a polyimide and paper, and dried to form an intermediate layer and a liquid for application for an abrasive layer is applied thereon and dried to laminate an abrasive layer so as to obtain an abrasive film used for texturing a magnetic disc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing film used for texturing a rigid magnetic disk.

[0002]

2. Description of the Related Art A rigid magnetic disk used as an external storage device such as an office or a personal computer has an increased recording density with the progress of thinning technology of recording layer by sputtering or other film forming means and precision processing technology. is doing. Also, due to the miniaturization of computers,
Substrate size is becoming smaller, and it is changing year by year as recording density rises.

In the rigid magnetic disk drive, the magnetic head and the magnetic disk medium operate by the CSS system,
Submicron unevenness formed on the magnetic disk substrate,
The attraction between the magnetic head and the magnetic disk medium is prevented. Further, by forming the irregularities in the circumferential direction, the magnetic particles formed by sputtering on the substrate are oriented in the circumferential direction, which contributes to the improvement of the magnetic characteristics. Further, the recess also affects the formation of the lubricating layer that is adsorbed on the protective layer.

The formation of submicron unevenness in the circumferential direction and the random direction on the magnetic disk substrate by the fixed abrasive grains and the loose abrasive grains is called texturing.
Usually, free-abrasive processing using a polishing film in which an abrasive such as alumina and silicon carbide powder is fixed by a binder resin on a polyester film substrate or diamond particles dispersed in an aqueous solution is performed.

[0005]

In the above free abrasive grains and the texturing process using the free abrasive grains, the dispersibility of the abrasive in the aqueous solution is poor with the free abrasive grains, and it is difficult to clean the disc after processing. There is a problem, even when processing with a polishing film used in a roll shape, due to the pressure difference acting on the coating film surface inside and outside the roll wound in multiple layers due to the winding tension during slit processing The phenomenon occurs that the abrasive material sinks into the binder resin at some parts and the surface roughness decreases. In order to solve these problems, the inventors have invented a texturing film obtained by applying a single layer of an abrasive having a sharp particle size distribution on a polyester substrate. (Japanese Patent Application No. 63-58392, 63-10403)
8 U.S. Pat. No. 4,974,373) It was found that this prevents variations in the polishing characteristics on the inner and outer circumferences of the tape. However, as the recording density is increased, the flying height of the magnetic head is reduced, so that the surface roughness of the textured surface is reduced, and in the grain size of 2 μm or less of the abrasive, the depth direction is affected by the coarse powder in the grain size distribution. It was confirmed that scratches occurred.

[0006]

The present invention relates to a polishing film for texturing of a magnetic disk, which comprises a substrate and a polishing layer formed on the substrate, and an intermediate layer comprising a soft resin and spherical particles between the polishing layer and the substrate. By providing the layer, the influence of scratches caused by the coarse powder was suppressed.

The substrate used in the present invention is not particularly limited, and polyethylene terephthalate, polyimide, paper, non-woven fabric and the like can be used.

The abrasive used in the polishing layer depends on the desired texturing, but since the present invention is particularly intended for texturing with low surface roughness, an average particle size of 2-4 μm is preferred. . As the abrasive, any abrasive such as alumina, silicon carbide or diamond can be used. The polishing layer has a single particle structure, and its thickness is the average particle size of the abrasive grains.

The spherical particles used in the intermediate layer preferably have an average particle size of 0.4 to 25 μm, although depending on the abrasive used for texturing. In particular, spherical polymers can be used as the spherical particles.
It can be selected from styrene resin, benzoguanamine / formaldehyde condensate, benzoguanamine / melamine formaldehyde condensate, melamine / formaldehyde condensate, nylon resin, and polyethylene resin. The coating thickness of the intermediate layer is in the range of 1 to 20 μm. The binder resin used in each layer may be a thermoplastic resin or a thermosetting resin.

[0010]

According to the polishing film of the present invention, since the intermediate layer in which the spherical particles are dispersed is used, it is possible to eliminate the influence of coarse particles in the polishing material powder in the polishing layer, and the scratch-free submicron texture is obtained. Ring processing is possible, and since the polishing layer is a single particle layer, processing performance without variation between rolls can be obtained. Examples of the present invention will be described below.

[0011]

[Explanation of Examples]

Example 1 Polymer beads having an average particle size of 0.4 μm (manufactured by Nippon Shokubai Co., Ltd.) were dispersed in a soft binder so as to have the following intermediate layer coating composition, and a crosslinking agent was added to the dispersion liquid to prepare a polyester substrate. A spherical particle intermediate layer having a coating thickness of 3, 5, 10 μm was formed on the upper surface. After curing these coating films at 50 ° C. for 48 hours, coating solutions prepared by dispersing aluminum oxide having an average particle diameter of 1, 2, 3 μm and silicon carbide powder in a binder resin so as to have the following polishing layer coating composition are used for various polymers. A polishing film was prepared by applying an abrasive material to the bead layer in a single particle layer.

Polymer bead intermediate layer coating composition Polymer beads 100 parts by weight Binder resin 40 parts by weight Curing agent 10 parts by weight Solvent 160 parts by weight Abrasive layer coating composition Abrasive material 100 parts by weight Binder resin 50 parts by weight Solvent 250 parts by weight

Example 2 The polishing film obtained in Example 1 was slit into a width of 38.1 mm, and 3.5 inches N was formed using a dedicated polishing apparatus.
The i-P plated aluminum substrate was textured. The processing line of the obtained circumferential method was observed with a scanning electron microscope (S-570 manufactured by Hitachi, Ltd.) to evaluate the presence or absence of scratches. The results are shown in Table 1. Further, the inside and outside of the polishing film wound in a roll shape were used, but no difference was observed between the two.

Processing conditions Processing time 20 sec Spindle speed 200 rpm Tape speed 150 mm / min Grinding liquid 1500 cc / min

[0015]

[Table 1]

Comparative Example A polishing film having a single particle structure having no intermediate layer was prepared in Example 1.
A 3.5 inch Ni-P plated aluminum substrate was manufactured in the same manner as in Example 2 and subjected to texturing under the same polishing conditions. The results are shown in Table 2.

[0017]

[Table 2]

[0018]

The following can be seen from Tables 1 and 2. 1. In the texturing process of rigid magnetic disk substrate, scratches were generated due to the influence of coarse particles in the abrasive grain size distribution with the conventional single grain structure in the abrasive of 2 μm or less. By providing the intermediate layer in which the spherical polymer beads are dispersed in the soft resin, the influence of the coarse particles is suppressed in the particle size of the fine powder of 1 to 3 μm, whereby a highly accurate processed surface corresponding to the high recording density can be obtained. 2. Since the abrasive grains are a single particle layer, there is no sinking of the abrasive into the resin at the inner peripheral portion of the roll, so there is no variation in processing performance between the inside and outside of the roll and between the rolls.

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Claims (7)

[Claims] 1. A polishing film formed by forming a polishing layer on a substrate, wherein an intermediate layer having spherical particles dispersed in a soft resin is provided between the polishing layer and the substrate. Abrasive film for texturing. 2. The base material is polyethylene terephthalate,
The polishing film according to claim 1, which is selected from polyimide, paper, and non-woven fabric. 3. The abrasive has an average particle diameter of 2 to 4 μm, and the spherical polymer beads have an average particle diameter of 0.4 to 25 μm.
Polishing film. 4. The polishing film according to claim 1, wherein the abrasive is selected from alumina, silicon carbide and diamond. 5. The spherical particles are acrylic-styrene resin,
The polishing film according to claim 1, which is selected from benzoguanamine / formaldehyde condensate, benzoguanamine / melamine formaldehyde condensate, melamine / formaldehyde condensate, nylon resin, and polyethylene resin. 6. The polishing film according to claim 1, wherein the binder resin of each layer is made of a thermoplastic resin or a thermosetting resin. 7. The polishing layer has a single particle structure, the thickness thereof is an average particle diameter of abrasive grains, and the coating thickness of the intermediate layer is 1 to 20 μm.
The polishing film according to claim 1, which is in the range of m.