JP3431111B2 - Polishing tape and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a magnetic hard disk,
The present invention relates to a polishing tape such as an optical fiber, a lens, and a magnetic head, which is used for precision finish polishing, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventional polishing sheets are generally prepared by uniformly and evenly applying a slurry prepared by mixing abrasive particles and a binder adhesive onto a plastic film by using a roller or a doctor blade. The film is formed by forming a polishing layer on the film (for example, JP-A-3-10772 and JP-A-3-264).
68, JP-A-3-92255, and JP-A-4-1907.
5 and Japanese Patent Publication No. 53-44714).

[0003]

However, in such a conventional polishing sheet, even if the surface of the slurry is flattened by using a roller or a doctor blade before drying, the slurry is applied to the sheet substrate. During the subsequent drying, unevenness is generated on the surface of this slurry, and protrusions are formed on the surface of the polishing layer. Therefore, when the surface of the object to be polished is polished by using the conventional polishing sheet, the projections of the irregularities bite into the surface of the object to be polished, so that precise finish polishing cannot be performed.

The reason why irregularities are formed on the surface of the polishing layer of the conventional polishing sheet will be described below with reference to FIG.

FIG. 6 is a partially enlarged cross-sectional view of a conventional polishing sheet, showing a slurry applied on the surface of a plastic sheet substrate and then dried.
FIG. 6A is a partially enlarged cross-sectional view of a conventional polishing sheet immediately after applying a slurry, and FIG. 6B is a partially enlarged cross-sectional view of a conventional polishing sheet during drying of a slurry.

In the conventional polishing sheet, as shown in FIG. 6 (A), the surface of the applied slurry 24 is flattened by using a roller or a blade after the application of the slurry 24. Therefore, the surface of the applied slurry 24 is dried. The front is flat.

However, as shown in FIG. 6 (B), the solvent evaporates from the binder adhesive 23 near the surface of the slurry 24 'to remove the heat of vaporization, so that the temperature of the binder adhesive 23 lowers. If there are relatively large abrasive particles 21, there is little binder adhesive 23 in the large volume portion of the abrasive particles 21, so there is almost no temperature drop due to evaporation.

That is, since the temperature of the binder adhesive 23 in the vicinity of the large abrasive particles 21 is higher than that of the other portions, the evaporation of some portions of the large abrasive particles 21 is more vigorous than that of the other portions. Drys faster. Therefore, the surface tension of the binder adhesive near the large abrasive grains 21 increases, and this surface tension acts in the direction of arrow 27 in FIG. 6 (B).

Since a large amount of the solvent remains in the portion having a large amount of the binder adhesive 23 and also has fluidity, the slurry 24 'in this portion, together with the relatively small abrasive particles 22, is present in the vicinity of the large abrasive particles 21. Binder adhesive 23
Is moved in the direction 27 in which the surface tension acts, and the slurry 24 ′ is attracted and rises to the portion where the large abrasive particles 21 are present to form a protruding portion 25, and a valley 26 is formed around the protruding portion 25. .

Therefore, in the past, efforts have been made to make the average particle size of the abrasive particles strictly, but the average particle size of the abrasive particles cannot be made exactly, and the particle size varies. It was

As a result, the slurry is dried and polished on the sheet substrate even though the average particle diameter of the abrasive particles is strictly equalized or the surface of the slurry is flattened before drying as in the prior art. When the layer is formed, a polishing sheet having irregularities or protrusions on its polishing surface is manufactured.

As described above, in the conventional polishing sheet, since the projections and depressions are formed on the polishing surface, the projections bite into the surface of the object to be polished, so that the surface of the object to be polished is provided with irregularities and a precise finish is obtained. I couldn't polish.

Therefore, an object of the present invention is to improve the flatness of the polishing surface of the polishing sheet and reduce the irregularities formed on the surface of the object to be polished, which is suitable for precise polishing, and its production. Is to provide a method.

[0014]

In order to achieve the above object, the polishing sheet of the present invention comprises a plastic sheet substrate and a slurry prepared by mixing abrasive particles applied to the surface of the plastic sheet substrate with a binder adhesive. In a polishing tape consisting of a polishing layer formed by drying,
After the slurry applied to the surface of the plastic sheet substrate is semi-dried to form a semi-dry slurry layer on the surface of the plastic sheet substrate, the surface of the semi-dry slurry layer can be peeled from the surface of the semi-dry slurry layer. A polishing layer is formed on the surface of the plastic sheet substrate by pressing with a member and then drying the semi-dry slurry layer.

In the polishing sheet of the present invention, first, a slurry obtained by mixing abrasive particles applied on the surface of a plastic sheet substrate and a binder adhesive is semi-dried to form a semi-dry slurry layer on the surface of the plastic sheet substrate. . After that, the surface of the semi-dry slurry layer is pressed with a peelable member that can be peeled from the semi-dry slurry layer, and then the pressed semi-dry slurry layer is dried to form a polishing layer on the surface of the plastic sheet substrate. Formed and manufactured.

In the polishing sheet and the method for producing the same of the present invention described above, it is desirable to use a material having a good releasability for the semi-dry slurry layer for the peelable member, and the peelable member is Teflon, polypropylene, It is preferably made of glass or a mirror-polished metal.

The peelable member may be a Teflon sheet, a polypropylene sheet, or a polyethylene sheet.

The abrasive particles include diamond (C), alumina (Al ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ), carborundum (Si) having an average particle size in the range of 0.1 μm to 30 μm.
C), chromium oxide (Cr ₂ O ₃ ) or cerium oxide (Ce
O ₂ ) or mixtures thereof can be used.

As the binder adhesive, nitrocellulose, acetyl cellulose, triethyl cellulose, polyvinyl acetal, polyacrylic acid ester, polyvinyl alcohol, polyvinyl chloride, epoxy resin, polyisobutylene, natural rubber or a mixture thereof can be used.

The plastic sheet substrate 1 has a thickness of 10
Sheets of polyester, polypropylene, polyethylene, or polyurethane in the range of μm to 150 μm can be used.

[0021]

[Operation] When most of the solvent contained in the slurry in which the abrasive particles applied to the surface of the plastic sheet substrate and the binder adhesive are mixed is evaporated to semi-dry the slurry,
A semi-dry slurry layer having no fluidity but plasticity is formed on the surface of the plastic sheet substrate.

The surface of the semi-dry slurry layer formed on the surface of the plastic sheet substrate has irregularities, but the semi-dry slurry layer has plasticity. A surface is formed along the surface of the peelable member. For example, when a roller having a flat surface is used as the peelable member and the surface of the semi-dry slurry layer is pressed, a flat surface is formed on the surface of the semi-dry slurry layer.

When the semi-dry slurry layer having a flat surface is dried, since the semi-dry slurry layer has no fluidity, the abrasive particles contained in the semi-dry slurry layer do not move and the residual solvent remains. Evaporate. That is, the solvent evaporates without changing the position of the abrasive particles on the surface of the semi-dry slurry layer. Here, since the solvent of the slurry is mostly evaporated and the solvent remaining in the semi-dry slurry layer is small, when the semi-dry slurry layer is dried, shallow recesses are formed around the abrasive particles due to evaporation of the residual solvent. .

At this time, the abrasive particles present on the surface of the polishing layer are evenly arranged at a certain height and project onto the surface of the polishing layer.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The polishing sheet and the method for producing the same according to the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 shows that the slurry applied to the surface of the plastic sheet substrate is semi-dried to form a semi-dry slurry layer on the surface of the plastic sheet substrate.

As shown in FIG. 1, in the practice of the present invention, first, a slurry obtained by mixing abrasive particles 2 applied on the surface of a plastic sheet substrate 1 and a binder adhesive is semi-dried to make the plastic sheet substrate 1 A semi-dry slurry layer 3 is formed on the surface.

Here, the semi-dry slurry layer 3 is dried to such an extent that the abrasive particles 2 cannot move, and the semi-dry slurry layer 3 is made into a flexible state that is easily plastically deformed. Further, as described above, unevenness is formed on the surface of the semi-dry slurry layer 3 because the slurry rises to the relatively large abrasive particles on the surface of the slurry (see FIG. 6).

FIG. 2 shows that the surface of the semi-dry slurry layer 3 shown in FIG. 1 is pressed by the peelable member 8, and FIG.
Shows that the surface of the semi-dry slurry layer shown in FIG. 1 was pressed by a peelable member to form a flat surface on the surface of the semi-dry slurry layer.

Next, as shown in FIG. 2, the surface of the semi-dry slurry layer 3 is pressed against the surface of the semi-dry slurry layer 3 by a peelable member 8 which is peelable.

Here, a roller is used as the peelable member 8, and axial pressure is applied to the surface of the semi-dry slurry layer 3 to rotate the semi-dry slurry layer 3 in the direction of arrow T in FIG. Pressure to flatten the surface of the semi-dry slurry layer 3 (see FIG.
However, as the peelable member 8,
For example, a flat plate may be used to apply pressure to the surface of the semi-dry slurry layer 3.

Since the semi-dry slurry layer 3 is in a flexible state such that it is easily plastically deformed, a flat surface 5 as shown in FIG. 3 is formed on the surface of the pressurized semi-dry slurry layer 3. To be done.

FIG. 4 shows that the surface of the semi-dry slurry layer is pressed by a peelable member and then the semi-dry slurry layer is dried to form a polishing layer on the surface of the plastic sheet substrate.

After pressing the surface of the semi-dry slurry layer 3 with the peelable member 8 as described above, the semi-dry slurry layer 3 is pressed.
Is dried to form the polishing layer 4 on the surface of the plastic sheet substrate 1 (see FIG. 4).

The polishing sheet of the present invention manufactured as described above has the plastic sheet substrate 1 as shown in FIG.
And a polishing layer 4 formed on the surface of the plastic sheet substrate 1, a recess 7 is formed between the abrasive particles 2 on the surface of the polishing layer 4, and the surface of the polishing layer 4 is formed. The heights of the existing abrasive particles 2 are uniform (see reference numeral 6 in FIG. 4).

Here, in the practice of the present invention, if the amount of solvent remaining in the semi-dry slurry layer 3 is too large, the peelable member 8 pressurizes the semi-dry slurry layer 3 to form the flat surface 5.
Since the semi-dry slurry 3 has fluidity when dried, the surface of the polishing layer 4 has the above-mentioned unevenness (see FIG. 6).
Is formed.

When the slurry applied to the plastic sheet substrate 1 is completely dried, the semi-dry slurry layer 3
Since there is no plastic deformability, the flat surface 5 cannot be formed on the surface of the semi-dry slurry layer 3 even if the semi-dry slurry layer 3 that is completely dried is pressed.

From this, the drying temperature at which the slurry applied to the plastic sheet substrate 1 is semi-dried, the plastic is applied so that the amount of the solvent remaining in the semi-dried slurry layer 3 is too large, or the slurry is not completely dried. The traveling speed of the sheet substrate 1 is adjusted. Here, in the preferred embodiment described later, the dry air A is blown onto the slurry to form the semi-dry slurry layer 3 on the surface of the plastic sheet substrate 1.
Therefore, the temperature and flow rate of the dry air A are also adjusted (see FIG. 5).

FIG. 5 is a conceptual diagram of an apparatus for producing the polishing sheet of the present invention.

As shown in FIG. 5, the apparatus for producing the polishing sheet of the present invention comprises a preliminary drying chamber 9, a peelable roller 8a, a peelable heat roller 8b, and a drying chamber 10.

In carrying out the apparatus for producing the polishing sheet of the present invention, the plastic sheet substrate 1 coated with the slurry S is run in the direction of the arrow t, and first, the dry air A is slurried into the slurry S in the preliminary drying chamber 9. After spraying to form the semi-dry slurry layer 3 on the surface of the plastic sheet substrate 1, pressure is applied by the peelable roller 8a and the peelable heat roller 8b to form a flat surface 5 on the surface of the semi-dried slurry layer 3, and , The plastic sheet substrate 1 passing through the drying chamber 10
The polishing layer 4 is formed on the surface of the.

Here, for example, the roller to which the slurry S is attached is rotated in the direction opposite to the running direction of the plastic sheet substrate 1 to bring it into contact with the surface of the plastic sheet substrate 1 so that the slurry S is deposited on the surface of the plastic sheet substrate 1. The slurry S is applied to the surface of the plastic sheet substrate 1 by a conventional means (not shown) for applying.

As shown in FIG. 5, in the apparatus for manufacturing the polishing sheet of the present invention, after the semi-dry slurry layer 3 formed on the surface of the plastic sheet substrate 1 is pressed by the peelable roller 8a, Further, pressure is applied by the heated peelable heat roller 8b.

This is because the flat surface 5 formed on the surface of the semi-dry slurry layer 3 by being pressed by the peelable roller 8a is heated by setting the axial pressure to be larger than the axial pressure of the peelable roller 8a. This is because the flatness of the flat surface 5 is further ensured by applying pressure again by the heat roller 8b.

Further, by sequentially pressing the semi-dry slurry layer 3 with the plurality of peelable members 8 in this manner, the flatness of the flat surface 5 is further ensured, and further, the thickness of the semi-dry slurry layer 3 is increased. The thickness can be made even thinner.

A preferred embodiment of the present invention will be specifically described below with reference to FIG.

1 kg of alumina having an average particle size of 1 μm was heated at a temperature of 1
After heating at 00 ° C for 1 hour to remove water, saturated polyester resin 900g, isocyanate curing agent 75g
And toluene, xylene, a mixed solvent of ethyl acetate and methyl ethyl ketone are mixed and stirred to obtain a viscosity of 80 cp to 5
A slurry S in the range of 00 cp was produced.

Using a conventional means (not shown) as described above, the slurry S is applied to the surface of the polyester substrate sheet 1 having a thickness of 20 μm in a direction indicated by a symbol t in FIG. 5 so as to have a thickness of 8 μm. Was applied at a coating speed of 5 m / min to 20 m / min.

As shown in FIG. 5, in the preferred embodiment of the present invention, first, in order to form the semi-dry slurry layer 3 on the surface of the polyester substrate sheet 1, the polyester substrate sheet 1 coated with the slurry S is preliminarily prepared. It is led to the drying chamber 9.

In the predrying chamber 9, 90 ° C. to 100 ° C.
Dry air at a temperature of ° C was blown onto the slurry at a flow rate of 1 m / sec to 5 m / sec (see symbol A in Fig. 5) to evaporate the mixed solvent contained in the slurry S.

As described above, the running speed of the polyester substrate sheet 1 is set in the range of 5 m / min to 20 m / min, and the dry air at a temperature of 90 ° C. to 100 ° C. is supplied at a flow rate of 1 m / sec to 5 m / min.
When sprayed on the slurry for 2 seconds, the amount of the solvent remaining in the semi-dry slurry layer 3 is too large, or the slurry is not completely dried, and the semi-dry slurry layer 3 having no fluidity but plastic deformability is formed on the polyester substrate. It can be formed on the surface of the sheet 1.

Next, the surface of the semi-dry slurry layer 3 is pressed by the peelable roller 8a to make the surface of the semi-dry slurry layer 3 flat, and then further pressed by the heated peelable heating roller 8b.
The flat surface 5 was formed on the surface of the semi-dry slurry layer 3.

The surface of the peelable roller 8a is covered with a Teflon sheet, and the axial pressure of the peelable roller 8a against the surface of the semi-dry slurry layer 3 is 1.0 kg to 1.2 kg.
It is in the range of kg.

The peelable heat roller 8b is heated in the range of 100 ° C. to 180 ° C. by a heater H connected to an external power source (not shown), and its axial pressure is 1.4 kg.
To 2.0 kg.

Next, it was passed through the drying chamber 10 kept at a temperature in the range of 120 ° C. to 180 ° C. to form the polishing layer 4 on the surface of the polyester substrate sheet 1 to manufacture the polishing sheet of the present invention.

Using the thus-prepared polishing sheet of the present invention and the conventional polishing sheet as described below, the hard disk surface is subjected to precise finish polishing to polish the hard disk surface. Later roughness was compared.

In the conventional polishing sheet, 1 kg of alumina having an average particle size of 1 μm was heated at a temperature of 100 ° C. for 1 hour to remove water, and then 900 g of a saturated polyester resin, 75 g of an isocyanate curing agent, toluene, xylene, and ethyl acetate. A slurry having a viscosity in the range of 80 cp to 500 cp is manufactured by mixing and stirring a mixed solvent of methyl ethyl ketone, and the slurry is applied to the surface of a polyester substrate sheet having a thickness of 20 μm while flattening the surface of the slurry with a blade so as to have a thickness of 8 μm. Manufactured by passing through a drying chamber maintained at a temperature in the range of 120 ° C to 180 ° C.

Using the polishing sheet of the present invention and the polishing sheet produced by the conventional method, the hard disk surface was subjected to precise finish polishing, and the roughness of the hard disk surface after polishing was compared. In the abrasive sheet, the hard disk surface roughness was reduced by at least 10% compared to the conventionally produced abrasive sheet.

[0059]

Since the polishing tape and the method for producing the same of the present invention are constructed as described above, the following effects can be obtained.

When the semi-dry slurry layer is pressed by the peelable member, a flat surface can be formed on the surface of the semi-dry slurry layer.

When the semi-dry slurry layer was dried, a shallow recess was formed around the abrasive particles due to evaporation of the residual solvent, and the abrasive particles were projected on the surface of the abrasive layer at a uniform height. A polishing surface can be formed.

When the polishing sheet of the present invention is used, the irregularities formed on the surface of the object to be polished by polishing can be reduced, and precise polishing can be performed.

[Brief description of drawings]

FIG. 1 shows a semi-dry slurry on the surface of a plastic sheet substrate after applying a slurry prepared by mixing abrasive particles and a binder adhesive on the surface of the plastic sheet substrate according to the present invention. FIG. 3 is a partially enlarged view of a semi-dry slurry layer and a plastic sheet substrate, showing a layer formed.

FIG. 2 is a partially enlarged view of the semi-dry slurry layer and the plastic sheet substrate, showing that the surface of the semi-dry slurry layer shown in FIG. 1 is being pressed by a peelable member.

3 is a partially enlarged view of the semi-dry slurry layer and the plastic sheet substrate, showing the surface of the semi-dry slurry layer shown in FIG. 1 pressed by a peelable member.

FIG. 4 shows a state in which the surface of the semi-dry slurry layer shown in FIG. 3 is pressed by a peelable member and then the semi-dry slurry layer is dried to form a polishing layer on the surface of a plastic sheet substrate. It is a partially expanded view of a polishing layer and a plastic sheet substrate.

FIG. 5 shows a conceptual diagram of an apparatus for producing an abrasive sheet according to the present invention.

FIG. 6 is a partially enlarged cross-sectional view of a conventional polishing sheet, showing a state where a slurry is applied to the surface of a plastic sheet substrate and then the slurry is dried.
FIG. 6A is a partially enlarged cross-sectional view of a conventional polishing sheet immediately after applying a slurry, and FIG. 6B is a partially enlarged cross-sectional view of a conventional polishing sheet during drying of a slurry.

[Explanation of symbols]

1. ． ． Plastic sheet substrate 2. ． ． Abrasive particles 3. ． ． Semi-dry slurry layer 4. ． ． Polishing layer 5. ． ． Flat surface formed on the surface of the semi-dry slurry layer 6. ． ． Line 7 showing that the height of the abrasive particles on the surface of the polishing layer is uniform. ． ． Recessed portion 8. ． ． Peelable member 8a. ． ． Peelable roller 8b. ． ． Peelable heat roller 9. ． ． Pre-drying room 10. ． ． Drying room A. ． ． Dry air blowing direction H. ． ． Heater S. ． ． Slurry T. ． ． Moving direction of peelable member t. ． ． 20. Running direction of plastic sheet substrate ． ． Plastic sheet substrate 21. ． ． Relatively large abrasive particles 22. ． ． Relatively small abrasive particles 23. ． ． Binder adhesive 24. ． ． Slurry before drying 24 '. ． ． Slurry during drying 25. ． ． Projection portion 26. ． ． Valley 27. ． ． Direction of surface tension

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Claims (3)

(57) [Claims] 1. An abrasive particle is mixed with a binder adhesive.
A slurry with a viscosity in the range of 80 cp to 500 cp
A plastic sheet running at a speed of m / min to 20 m / min
Step of applying to the surface of the coated substrate, dry air at a temperature of 90 ° C to 100 ° C, and a flow rate of 1 m / sec.
To 5 m / sec to spray the slurry applied to the surface of the plastic sheet substrate to form a semi-dry slurry layer having no fluidity but plastic deformation on the surface of the plastic sheet substrate. step, the semi-dried slurry layer and the surface of the step is pressurized with strippable member can be peeled off with respect to the semi-dried slurry layer, and said pressurized the semidry slurry layer surface of the plastic sheet substrate is dried a method of making an abrasive tape comprising a step of forming the abrasive layer. 2. The peelable member is Teflon, polypropylene, glass, or mirror-polished metal.
1. The method for producing an abrasive tape according to 1 . 3. The peelable member is a Teflon sheet, a polypropylene sheet, or a polyethylene sheet.
The method for manufacturing the polishing tape according to claim 1 .