JP2000000771A - Polishing sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing sheet for wet polishing to perform precise polishing without unnecessarily flawing the surface of a work even when there is unevenness in the grain size of using polishing particle particles, and prevent freeing of polishing particles from a polishing layer during polishing. SOLUTION: A polishing sheet comprises a substrate sheet 11 having a number of recessed parts 12 formed in a surface; and a polishing layer 15 formed that slurry prepared by mixing together polishing particles 14 and 14' and a binder adhesive is evenly applied on the surface of the substrate sheet 11 and dried. A binder adhesive 13 in a dry state during wet polishing is brought into contact with cooling liquid and softened to indicate flexibility and forms a flexible binder. The polishing particles 14 and 14' are held by the flexible binder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to metals, glass, minerals,
Polishing of ceramics, plastics, wood, etc., especially
The present invention relates to a polishing sheet used for precise wet polishing of an end face of an optical fiber, a lens, a magnetic disk, a surface of a precision machine component, and the like.

[0002]

2. Description of the Related Art Generally, in wet polishing using a polishing sheet having abrasive particles disposed on the surface thereof, polishing is performed by pressing the polishing sheet against the surface of the object to be polished and supplying a cooling liquid. This is performed by relatively moving the sheet and the object to be polished.

A conventional polishing sheet used for such wet polishing includes a slurry in which abrasive particles such as aluminum oxide and a binder adhesive such as a polyester resin are mixed with a flexible substrate such as a plastic sheet or a nonwoven fabric. There is a substrate in which a polishing layer is formed on the surface of a substrate sheet by uniformly coating and drying the surface of the sheet (see, for example, JP-A-53-68490). Further, there is also a type in which abrasive particles are fixed to the surface of a flexible substrate sheet with a binder adhesive to form a polishing layer on the surface of the substrate sheet (see, for example, JP-A-62-28177).
No.).

[0004] In these conventional polishing sheets, the abrasive particles in the polishing layer are firmly fixed by a binder adhesive in a dry state.

[0005] That is, if there is a variation in the particle size of the abrasive particles, the abrasive particles having a relatively large particle size protrude abnormally and are firmly fixed to the polishing layer. Unnecessary scratches will be made.

For this reason, fine classification of abrasive particles is performed. However, at present, even if fine classification of abrasive particles is performed, for example, abrasive particles having a particle size of about 0.5 to 5.0 μm are classified. Also, there is a distribution width of the particle diameter of about 0.5 μm to 2.0 μm centering on the particle diameter of 1 μm (for example, see Japanese Patent Application Laid-Open No. 9-206627), and the particle diameter of the abrasive particles used varies.

For this reason, in the above-mentioned conventional polishing sheet, since the particle size of the abrasive particles used varies, the abnormally protruding abrasive particles are firmly fixed to the polishing layer, and the polished particles are polished during polishing. There is a problem that it is inevitable that unnecessary scratches are made on the surface of an object.

[0008] Other conventional polishing sheets include those in which a mixture of abrasive particles and a water-soluble resin is uniformly applied to the surface of a flexible substrate sheet and dried to form a polishing layer on the surface of the substrate sheet. (For example, see Japanese Patent Application Laid-Open No. 5-228845).

In this polishing sheet, the abrasive particles are temporarily held in a dried product of the water-soluble resin, and in wet polishing, the dried product of the water-soluble resin is dissolved by the cooling liquid to release the abrasive particles. The surface of the object to be polished is polished by the abrasive particles thus liberated. However, in the polishing using such loose abrasive particles, the loose abrasive particles polish the edge when polishing near the edge of the object to be polished, and unnecessary roundness, that is, loose edge is formed on the edge. And cannot perform precise polishing.
There is a problem.

[0010] Therefore, an object of the present invention is to perform precise polishing without causing unnecessary scratches on the surface of the object to be polished, even if the particle size of the abrasive particles used varies, and the polishing layer is removed during polishing. An object of the present invention is to provide an abrasive sheet for wet polishing, in which abrasive particles are not released.

[0011]

The polishing sheet of the present invention comprises:
It comprises a substrate sheet having a large number of concave portions on its surface, and a polishing layer formed by uniformly applying a slurry of a mixture of abrasive particles and a binder adhesive on the surface of the substrate sheet and drying it.

In order to solve the above-mentioned problems, the polishing sheet of the present invention is characterized in that during wet polishing, a binder adhesive in a dry state softens upon contact with a cooling liquid and exhibits flexibility, and becomes a flexible binder. Particles are held by this flexible binder.

Here, the soft binder does not firmly fix the abrasive particles during wet polishing or does not release the abrasive particles, and as described below,
During wet polishing, the abrasive particles are retained in the polishing layer.

That is, during wet polishing, the abrasive particles on the surface of the polishing layer are pressed against the surface of the object to be polished and move relatively to the object to be polished. At this time, the abrasive particles on the surface of the polishing layer, particularly the abrasive particles that abnormally protrude from the surface of the polishing layer, are pushed down into the soft binder softened by the cooling liquid as described above, and are pushed into the surroundings. It is almost the same as the projection amount of certain abrasive particles, and is not separated from the polishing layer by being dragged by the object to be polished.

Further, even when the particle size of the abrasive particles which abnormally protrude from the surface of the polishing layer is remarkably large, for example, when the particle size of the abrasive particles is substantially the same as the thickness of the polishing layer, the substrate sheet is Since there are many recesses on the surface of the substrate sheet, the lower portion of such abrasive particles is caught by the recesses on the surface of the substrate sheet, and rotates relative to the recesses on the substrate sheet due to relative movement with the object to be polished. It is pushed down into a suitable binder and pushed in, and the amount becomes equal to the amount of projection of surrounding abrasive particles, and is not dragged by the object to be polished and released from the polishing layer.

[0016] As described above, the soft binder forms the soft binder without releasing abrasive particles on the surface of the polishing layer (particularly, abrasive particles that abnormally protrude from the surface of the polishing layer) during wet polishing. The abrasive particles are held down to the same extent as the protruding amount of the surrounding abrasive particles, and the abrasive particles are held in such a flexible binder. The surface is pressed uniformly by the abrasive particles on the surface of the polishing layer.

As the binder adhesive, carboxymethylcellulose sodium salt, hydrophilic acrylic resin, hydrophilic polyester resin, or a mixture thereof is used.

As the substrate sheet, a plastic sheet having a large number of concave portions formed on the surface thereof, a foamed polyurethane sheet having a large number of concave portions formed of cell voids on the surface, or a nonwoven sheet having a large number of concave portions formed on the surface is used. You.

The above-mentioned polishing sheet of the present invention is obtained by uniformly applying a slurry obtained by mixing the above-mentioned binder adhesive and abrasive particles on the surface of the above-mentioned substrate sheet and drying it, thereby forming a polishing layer on the surface of the substrate sheet. Manufactured by forming.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a polishing sheet 10 of the present invention comprises a substrate sheet 11 having a large number of recesses 12 on its surface.
And a polishing layer 15 formed by uniformly applying and drying a slurry in which abrasive particles 14 and a binder adhesive are mixed on the surface of the substrate sheet 11 (in the figure, a relatively large particle size). The abrasive particles are denoted by reference numeral 14 'and the binder adhesive in the dry state is denoted by reference numeral 13).

The polishing sheet 10 shown in FIG. 1 is prepared by mixing and stirring abrasive particles 14, a binder adhesive, and water (and optionally adding a small amount of alcohol or ketones) to form a slurry.
The slurry is manufactured by uniformly applying the slurry on the surface of the substrate sheet 11 and drying. Here, the slurry can be applied to the surface of the substrate sheet 11 by a known coating method such as a kiss roll coating method or a gravure coating method.

As the binder adhesive, sodium carboxymethylcellulose, a hydrophilic acrylic resin, a hydrophilic polyester resin, or a mixture thereof is used. These materials have a property of softening and exhibiting flexibility when a cooling liquid comes into contact with the binder adhesive 13 in a dry state, thereby forming a flexible binder.

As the substrate sheet 11, a plastic sheet made of polyester, polyethylene naphthalate, or the like having a large number of concave portions formed on the surface can be used. Such a concave portion can be formed by causing hard crystal particles to collide with the surface of the plastic sheet with compressed air or the like (sandblasting). Further, as the substrate sheet 11, a sheet of foamed polyurethane in which a surface of a sheet-shaped urethane foam having a large number of cell voids inside is thinly shaved to form a large number of concave portions formed of cell voids on the surface, or a large number of concave portions on the surface. May be used. The thickness of such a substrate sheet 11 is preferably about several μm to 100 μm, but can be appropriately selected according to the use of the polishing sheet.

The abrasive particles 13 have an average particle size of 0.004 μm to 20 μm.
Known abrasive particles such as diamond, aluminum oxide, iron oxide, silicon dioxide, silicon carbide, chromium oxide, cerium oxide, etc. can be used. The material and particle size of the abrasive particles 13 can be appropriately selected according to the use of the abrasive sheet.

In the wet polishing using the polishing sheet 10 of the present invention shown in FIG. 1, for example, the wet polishing apparatus shown in FIG.
It can be done using 30, 30 '.

In the wet polishing using the wet polishing apparatus 30 shown in FIG. 2, the polishing sheet 10 is cut into a tape to produce a polishing tape 10 ', and this polishing tape 10' is disc-shaped via a roller 32. The polishing liquid is supplied from the nozzle 31 while the polishing tape 10 ′ is running in the direction of the arrow T in a state where the polishing tape 10 ′ is pressed against the surface of the polishing target 20, and the polishing target 20 is rotated in the direction of the arrow R. .

In the wet polishing using the wet polishing apparatus 30 'shown in FIG. 3, the polishing sheet 10 is cut into a disk to produce a polishing pad 10 ", and the polishing pad 10" is placed on the turntable 33. Then, the end face of the columnar object to be polished 20 ′ is pressed against the polishing pad 10 ″ on the turntable 33, and
The cooling liquid is supplied from the nozzle 31 while rotating the nozzle 33 in the direction of the arrow S.

During wet polishing using the apparatus 30, 30 'as shown in FIG. 2 or 3, the dry binder adhesive in the polishing layer 15 of the polishing sheet 10 shown in FIG.
13 softens and shows flexibility, and becomes a flexible binder.

Since there is a variation in the particle size of the abrasive particles 14 used, as shown in FIG. 1, the abrasive particles 14 ′ may protrude abnormally in the polishing layer 15.

The abnormally protruding abrasive particles 14 '
When pressed against the surface of 20 and moved relatively to the polished objects 20 and 20 ', the binder adhesive 13 which was in a dry state becomes a soft binder by cooling water, so that it is below the abrasive particles 14'. The portion is caught in the concave portion 12 of the substrate sheet 11, is pushed down into a flexible binder in the vicinity of the concave portion 12 of the substrate sheet 11, is pushed in, becomes approximately the same as the protrusion amount of the surrounding abrasive particles, It is not separated from the polishing layer 15 by being dragged by the objects to be polished 20, 20 '. As a result, the surfaces of the objects to be polished 20, 20 'are pressed uniformly by the abrasive particles 14, 14' on the surface of the polishing layer 15.

[0031]

EXAMPLES Example 1 A polishing sheet of the present invention was manufactured, and the surface of a magnetic hard disk was polished.

The binder adhesive used in the production of the polishing sheet of the present invention in Example 1 is a mixture of sodium carboxymethylcellulose and a hydrophilic polyester resin in a weight ratio of 6: 4. The binder adhesive, the abrasive particles, and water were mixed and stirred at a weight ratio of 3: 2: 95 to produce a slurry. Aluminum oxide having an average particle size of 3 μm was used as the abrasive particles. Next, by shaving the surface portion, on the surface of a 16 μm thick urethane foam sheet having a large number of recesses formed on the surface, the above slurry was uniformly applied by a kiss roll coating method and dried, and the present invention An abrasive sheet was manufactured.

The polishing sheet thus manufactured is cut into a tape to produce a polishing tape, and wet polishing of the surface of the Ni-P plated aluminum magnetic hard disk is performed using the apparatus shown in FIG. Was done.

The wet polishing was performed by rotating the magnetic hard disk and supplying the cooling liquid while running the polishing tape while the polishing tape was pressed against the surface of the magnetic hard disk.

As a result, a uniform magnetic hard disk surface without unnecessary scratches was obtained.

Example 2 A polishing sheet of the present invention was manufactured, and the end face of the columnar glass was polished. The abrasive sheet of the present invention of Example 2 was made of 100 μm thick polyester having a large number of concave portions formed by sandblasting on the surface (hard crystal particles were sprayed with compressed air to form a large number of concave portions on the surface of the substrate sheet). Substrate sheet was used. Carboxymethylcellulose sodium salt is used as the binder adhesive, and the binder adhesive, abrasive particles, and water are used in two parts:
A slurry was produced by mixing and stirring at a weight ratio of 2:96.
Silicon dioxide having an average particle size of 0.005 μm was used as the abrasive particles. Next, this slurry was uniformly applied to the surface of the above-mentioned substrate sheet and dried to produce a polishing sheet of the present invention.

The polishing sheet thus manufactured was cut into a disk to produce a polishing pad, and the end face of the columnar glass was wet-polished using the apparatus shown in FIG.

The wet polishing was performed by pressing the end face of the columnar glass against a polishing pad stuck on a rotating disk and supplying a cooling liquid while rotating the rotating disk.

As a result, a uniform glass surface without unnecessary flaws was obtained without causing edge loosening at the edge of the end face of the columnar glass.

[0040]

As described above, the abrasive sheet of the present invention is constructed as described above, so that even if the particle size of the abrasive particles in the polishing layer varies, the abnormally protruding abrasive particles in the polishing layer are soft. By being pushed down into the binder and pushed in, the abrasive particles on the surface of the polishing layer are not separated and are almost the same as the protrusion amount of the surrounding abrasive particles, and are covered by the abrasive particles on the surface of the polishing layer. Since the surface of the object to be polished is pressed uniformly, there is an effect that precise polishing can be performed without causing unnecessary scratches on the surface of the object to be polished.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a polishing sheet of the present invention.

FIG. 2 is a schematic diagram of an apparatus for wet polishing.

FIG. 3 is a schematic diagram of another apparatus for wet polishing.

[Explanation of symbols]

 10: polishing sheet of the present invention 10 ': polishing tape 10 ": polishing pad 11: substrate sheet 12: recess 13: dried binder adhesive 14: abrasive particles 14 ': abrasive particles having a relatively large particle size 15: polishing layer 20, 20': object to be polished 30, 30 ': apparatus for wet polishing 31: nozzle for cooling liquid supply 32 ・ ・ ・ Roller 33 ・ ・ ・ Rotating disk R ・ ・ ・ Rotation direction of disk-shaped polishing object S ・ ・ ・ Rotation direction of rotating disk T ・ ・ ・ Running direction of tape-shaped polishing sheet

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Saito 3-4-1 Musashino, Akishima-shi, Tokyo Japan Micro Coating Co., Ltd. F-term (reference) 3C063 AA03 AB07 BC03 BC09 BG01 BG03 CC16 EE01 EE02 FF30

Claims (6)

[Claims] 1. A substrate sheet having a large number of concave portions on its surface, and a polishing layer formed by uniformly applying a slurry obtained by mixing abrasive particles and a binder adhesive on the surface of the substrate sheet and drying the slurry, During wet polishing, the binder adhesive in a dry state,
A polishing sheet which softens when exposed to a cooling liquid, exhibits flexibility, becomes a flexible binder, and the abrasive particles are held by the flexible binder. 2. The polishing sheet according to claim 1, wherein the binder adhesive is carboxymethylcellulose sodium salt, a hydrophilic acrylic resin, a hydrophilic polyester resin, or a mixture thereof. 3. The substrate sheet may be a plastic sheet having a large number of recesses formed on the surface, a foamed polyurethane sheet having a large number of recesses formed of cell voids on the surface, or a non-woven fabric sheet having a large number of recesses on the surface. The polishing sheet according to claim 1, wherein the polishing sheet is provided. 4. A step of forming a polishing layer by uniformly applying a slurry obtained by mixing abrasive particles and a binder adhesive on the surface of the substrate sheet having a large number of concave portions on the surface and drying the slurry, The binder adhesive in a dry state,
A method for producing a polishing sheet, wherein the polishing sheet softens when contacting a cooling liquid, exhibits flexibility, becomes a flexible binder, and the abrasive particles are held by the flexible binder. 5. The method for producing a polishing sheet according to claim 4, wherein the binder adhesive is carboxymethyl cellulose sodium salt, a hydrophilic acrylic resin, a hydrophilic polyester resin, or a mixture thereof. 6. The substrate sheet may be a plastic sheet having a large number of recesses formed on a surface thereof, a foamed polyurethane sheet having a large number of recesses formed of cell voids on a surface thereof, or a non-woven fabric sheet having a large number of recesses formed on a surface. The method for producing a polishing sheet according to claim 4.