JP5209284B2 - Abrasive sheet and method for producing abrasive sheet - Google Patents

Description

  The present invention relates to a polishing sheet for smoothly polishing the surface of various objects to be polished such as a magnetic disk substrate, a silicon wafer, a glass substrate for a display device, an end face of an optical fiber and a lens, and in particular, polishes the object to be polished very precisely. The present invention relates to a polishing sheet and a method for producing the same.

  In order to polish the surface of the object to be polished smoothly and flatly, polishing is performed using fine abrasive grains as much as possible, but the polishing method is roughly divided to supply the abrasive grains to the object to be polished from the outside. There are a free-abrasive method for polishing and a fixed-abrasive method for polishing using a polishing sheet in which the polishing abrasive is fixed to a substrate. Of these, the fixed abrasive method does not require a large amount of abrasive as the free abrasive method, and the substrate sheet to which the abrasive is fixed can be realized in various shapes, and thus is widely used. .

  In the fixed abrasive grain type polishing sheet, an organic resin such as polyethylene terephthalate, a woven fabric, a non-woven fabric, or the like is selected as a substrate, and fine particles of an inorganic abrasive such as alumina, silica, diamond, etc. are placed on the substrate. It is configured to be fixed with a binder.

  The polishing performance of the polishing sheet is determined by the mixing ratio of the abrasive grains themselves and the resin, the fixing thickness, and the like, but particularly depends on the properties of the abrasive grains. The abrasive grain material, grain size, shape, etc. are important factors for the properties of the abrasive grains. However, even if the abrasive grains themselves are optimized, the fixed layer to which the abrasive grains are secured in order to fully demonstrate the performance. In other words, the arrangement of the individual abrasive grains is another important factor.

  In particular, in order to polish the object to be polished with high precision, an arrangement of abrasive grains such that individual abrasive grains are agglomerated and fixed to a substrate is not preferable. When viewed microscopically, the individual abrasive grains are often not arranged in a uniform manner, and if they cause agglomeration, it is easy to invite an arrangement in which clusters are scattered.

  With such an array of abrasive grains, the surface roughness of the polishing sheet becomes uneven, and only unfavorable polishing that causes scratches on the surface of the object to be polished can be achieved.

  Therefore, in order to eliminate the occurrence of scratches as described above, a polishing sheet has been devised in which the grain size of the abrasive grains is made as uniform as possible and the abrasive grains are fixed in a single layer (Patent Documents 1 and 2). . For example, an abrasive single layer shown in FIG. 2 of Patent Literature 1 and a diamond abrasive grain single layer abrasive sheet shown in FIG. 1 of Patent Literature 2 are known.

  Patent Document 1 describes that an abrasive single layer can be easily obtained simply by mixing a binder and abrasive grains and applying the mixture to a base material, and does not mention any specially devised application method. On the other hand, Patent Document 2 describes a special method for obtaining a single layer of abrasive grains. In the electrolytic solution in which abrasive grains are dispersed, the abrasive grains are fixed by electrodeposition, or an organic binder and abrasive grains are bonded. A method of roll coating the blend is disclosed.

  As described above, a polishing tape having a single layer of abrasive grains is disclosed. However, when viewed microscopically, in the conventional example, the surface of each abrasive grain that comes into contact with the object to be polished is covered with a binder. It was a configuration that. For example, in the method described in Patent Document 1, since only a mixture of abrasive grains and a binder is applied, the surface of the abrasive grain contacting the object to be polished is shown by a dotted line in FIG. It can be seen that it remains covered with the binder shown in. As described above, when the abrasive grains are covered with a binder that does not contribute to polishing, the polishing performance is remarkably deteriorated.

  In addition, although Patent Document 2 describes that the abrasive grains are not covered with a binder in the figure, the inventors have studied and the binder remains on the abrasive grain surface simply by applying a mixture of the binder and the abrasive grains. It turned out to be a challenge.

  Moreover, there is a limit to the degree of classification when the classification is performed so that the size of the abrasive grains is uniform, and the abrasive grains have a certain particle size distribution. When the abrasive grains having such a particle size distribution are only applied, the most advanced portion of the abrasive grains that come into contact with the object to be polished (that is, the part that comes into contact with the object to be polished) is not perfectly linear when viewed microscopically. There is no difference in its height. This is not preferable because, when the object to be polished is polished, abrasive grains that come into contact with the object to be polished and contribute to the polishing are mixed with abrasive grains that do not come into contact with the polishing object and do not contribute much to the polishing. In this patent, the most advanced part of the abrasive grains that come into contact with the object to be polished is referred to as a cutting blade, and the fact that the cutting blade is in a straight line is referred to as the cutting blades being aligned.

  Therefore, in order to realize a state in which the abrasive grains can be fixed in a single layer and the cutting edges of the individual abrasive grains are not covered with anything other than abrasive grains such as a binder and an electrodeposition material that degrade the polishing performance. A method for removing the binder adhering to the abrasive grain surface after forming a single layer has been devised and disclosed (Patent Document 3). In the method described in Patent Document 3, the surface of the single-layer abrasive is exposed by removing the binder on the surface of the abrasive by irradiating ultraviolet rays after applying a mixture of the abrasive and binder, and polishing performance. Is preventing the decline.

  However, this method requires a long time to remove the binder on the surface of the abrasive grains and is poor in mass productivity. Further, since the ultraviolet rays wrap around not only the surface of the abrasive grains but also the side faces of the abrasive grains, the binder on the side faces of the abrasive grains that should serve to hold the abrasive grains firmly is also removed, and as a result, the abrasive grains are liable to fall off.

  In addition to the above, there is a disclosed method as a method for forming a single layer with the abrasive grain surface exposed (Patent Document 4). In the case of Patent Document 4, the abrasive grains are first made into a slurry mixed with a low-viscosity first binder, and the slurry is applied on the substrate so that the abrasive grains form a single layer. Next, by drying, the binder shrinks and the surface of each abrasive grain protrudes beyond the binder part. Next, the protrusion is pushed into the second binder having a high viscosity so as to cover the protrusion. When the second binder is dried, each abrasive grain is held more firmly by the second high viscosity binder than by the first low viscosity binder. Therefore, by peeling the first binder, the abrasive grains are held by the second binder, and a single layer with the abrasive grain surface exposed is obtained.

  However, in this method, the first binder is not always easily separated from the abrasive grains, and there is a disadvantage that the first binder tends to be a polishing sheet that still covers the abrasive grain surface with the first binder remaining.

On the other hand, the polishing article described in Patent Document 5 is such that a plurality of polishing composites are exposed on the surface of the base sheet and arranged at a uniform interval, but the apparatus configuration is complicated. On the other hand, there is a drawback in that it cannot always be formed so that the tips of the abrasive composites are aligned.
JP-A-1-234169 Japanese Patent Laid-Open No. 4-129660 JP-A-2-243271 Japanese Patent No. 3314154 Japanese Patent Laid-Open No. 5-253852

  As described above, in order to obtain an abrasive sheet that forms abrasive grains in a single layer and exhibits a completely exposed portion in which the surface of the cutting blade is not covered with a binder, the conventional method can obtain a single layer. The binder remains on the surface of the cutting blade. Alternatively, in the conventional method for removing the residual binder, the removal is poor in mass productivity and not complete.

  Further, since the cutting blades are not aligned, the original polishing performance of the abrasive grains cannot be fully exhibited. In addition, in a polishing sheet prepared by a conventional method, adjacent abrasive grains often come into contact with each other when viewed in the plane direction. It has been found that one of the causes is that a polishing residue of a material to be polished damages the material to be polished as a generation mechanism of a polishing scratch that becomes a problem in polishing. In order to eliminate polishing scratches caused by such a mechanism, it is necessary to efficiently discharge polishing residues. In normal polishing, a constant load is applied to the polishing sheet or the object to be polished, so that the object to be polished and the polishing sheet are in close contact with each other and it is difficult to discharge the polishing residue. In the conventional example, the abrasive grains are in contact with each other as viewed in the plane direction, and the polishing residue is more difficult to be discharged.

  Accordingly, an object of the present invention is to provide a polishing sheet that can solve the three problems of efficiently discharging polishing residues at the same time as aligning the cutting edges and cutting edges of the abrasive grains.

In order to achieve the above object, the present invention proposes a polishing sheet comprising a base material and abrasive grains that form a single particle layer fixed on the surface of the base material by an adhesive. The abrasive sheet is characterized in that the abrasive grains are distributed at a distance from each other while aligning the tip portions in contact with the object to be polished on the same plane.

Furthermore, the present invention proposes that a single layer of abrasive grains fixed on a base material by an adhesive exposes a portion of the adhesive that contacts the object to be polished and aligns the tips thereof on the same plane. A method for producing a polishing sheet comprising: a first step of forming a temporary fixing material film having a numerical value smaller than an average particle diameter of the abrasive grains on a temporary substrate; A second step of spraying the temporary adhering material film on the temporary base material so as to contact the temporary base material; and a third step of pressing the base material coated with the adhesive toward the abrasive grains. A fourth step of curing the pressure-bonded adhesive, and a fifth step of peeling the temporary base material and further removing the temporary fixing material film after the adhesive is cured. It is the manufacturing method of the characteristic abrasive sheet.

And in this invention, in order to solve the said subject, the water-soluble or organic acid water-soluble film | membrane of the thickness of 1/10-2/3 of the average particle diameter of an abrasive grain is formed in a temporary base material, and this abrasive grain is used. negative or positive is charged to the same polarity, and a container of the spray device to spray the abrasive grains are charged to the abrasive grains of the same polarity, and the water-soluble or organic acid water-soluble film the temporary substrate as a ground potential Sprinkle the abrasive grains so that the tips of the abrasive grains are in contact with the temporary base material, and then press the resin that fixes the abrasive grains on the opposite side of the temporary base material to cure the resin. After that, a novel production method of peeling the temporary base material and then removing the film is adopted, thereby obtaining a polishing tape having excellent polishing performance.

Prepare the temporary substrate to first fixing the abrasive grains by the method of the present invention, applying a water-soluble or organic acid water-soluble thin film on a provisional substrate. Next, abrasive grains are dispersed on the water-soluble or organic acid water-soluble coating film. The abrasive grains are dispersed by electrostatically charging the abrasive grains to the same positive or negative polarity and electrically setting the temporary base material to the ground potential.

In this case, the inner wall of the electrostatic spraying device is charged to the same polarity as the abrasive grains, so that the abrasive grains are efficiently dispersed on the temporary base material without adhering to the inner wall of the container. By appropriate selection of the thickness of the water-soluble film or organic acid water-soluble film and the potential difference between the electrostatic charging voltage and the ground potential, the abrasive grains contact the temporary substrate in the water-soluble film or organic acid water-soluble film. The part of the abrasive grain that is pushed in in a state of being opposite to the temporary base material protrudes from the water-soluble film or the organic acid water-soluble film.

Next, a fixing material such as a resin is applied so as to cover the protruding portion of the abrasive grains. The fixing material is solidified and firmly holds the abrasive grains. Next, the temporary base material is peeled off, and finally the water-soluble film or organic acid water-soluble film is dissolved with water or acid to obtain an ideal polishing sheet in which cutting edges are aligned and the abrasive grains are spaced apart in the plane direction. . The new technology and the resulting product are described in detail below.

  The present invention can provide a polishing sheet as an abrasive that does not generate polishing scratches and can efficiently perform polishing with good surface roughness.

In particular, according to the present invention, a water-soluble or organic acid water-soluble material is used as a temporary fixing material, and at the same time, the abrasive grains are viewed in a planar direction by charging the abrasive grains to the same polarity and keeping the temporary substrate at the ground potential. Abrasive sheets spaced apart from one another are obtained. Further, the cutting blades are completely exposed and aligned, so that extremely excellent polishing performance is exhibited as an abrasive sheet.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a partial cross-sectional view of an abrasive sheet according to the present invention, FIGS. 2A to 2H are schematic views showing a manufacturing process of the abrasive sheet according to the present invention, and FIG. FIG. 4 is a schematic view showing a spraying device, FIG. 4 is a photograph showing distribution of abrasive grains after spraying abrasive grains in the present invention, and FIG. 5 is a schematic perspective view of a test piece processing apparatus using a polishing sheet according to the present invention.

As shown in FIG. 1, the abrasive sheet according to the present invention is formed by adhering a layer of an adhesive resin 5 on one surface to a base material 4 which is a film-like base material, and at the same time an adhesive resin 5 Firmly adheres the abrasive grains 31-33.

The substrate 4 is made of a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, a polyolefin resin such as polyethylene or polypropylene, an acrylic resin mainly composed of polystyrene, vinyl chloride, polyvinyl alcohol or methacryl alcohol, polycarbonate, or the like. is there.

The abrasive grains 31 to 33 have no aggregation and are formed in a single particle layer. In the abrasive grains 31 to 33, the part opposite to the base 4 is a cutting blade, and this cutting blade is in contact with the virtual line 35. That is, the cutting blades are in a completely aligned state, and the cutting blades are not covered with a substance that adversely affects the abrasiveness. Further, the abrasive grains 31 to 33 are held in a state where they are not in close contact with each other but are separated from each other. That is, the cutting blades, which are the tip portions of the abrasive grains in contact with the object to be polished, including abrasive grains (not shown) other than the abrasive grains 31 to 33 are located on the same plane and spaced apart.

Although those adhesive resin 5 having excellent adhesion to the substrate 4 is selected, the selection can be applied an adhesive resin used universally. It is also preferable to use a UV resin when the adhesive resin is cured.

  The manufacturing process of the abrasive sheet according to the present invention is shown in FIGS.

FIG. 2 (h) is a product schematic diagram of the finally obtained abrasive sheet. The abrasive sheet comprises a base material 4, abrasive grains 31 to 33, and an adhesive resin 5 that firmly holds the abrasive grains 31 to 33. The cutting blades of the abrasive grains 31 to 33 are in contact with the object 8 to be polished.

Such an abrasive sheet is produced through the steps shown in FIGS. 2 (a) to 2 (g). First, the temporary base material 1 is prepared. The material of the temporary substrate 1 polymer, Si wafer, it is possible to use a variety of metals. There are no major restrictions on the material itself, but the surface must be smooth. The smoothness depends on the size of the abrasive grains used. For example, when the average diameter of the abrasive grains is 20 microns, the average surface roughness is about 1 micron or less, and when the average grain diameter is 5 microns, it is 0. A smoothness of 5 microns or less is acceptable.

Then film 2 (as appropriate, referred to as "film") of the water-soluble or organic acid water-soluble thin temporary fixing material of ability to provisionally fix the abrasive grains on the temporary substrate 1 to apply the. As the water-soluble film material, polysaccharides, glue, starch, gelatin and the like are used. Specifically, polysaccharides such as glycogen, cellulose, dextran, and dextrin, polyvinyl alcohol, acrylic acid polymers, water-soluble polymers (glue) such as polyethylene oxide, starch produced from plants such as corn and straw, animal protein The gelatin etc. which consist of are listed.

  Organic acid water-soluble materials that are difficult to dissolve in water but have organic acid added are also useful. For example, chitin and polyβ1,4 glucosamine (chitosan) from which acetyl groups are removed from chitin are used. It is done. In particular, chitosan is a material suitable for the present invention because it is soluble in vinegar and has no problem in terms of safety.

  An already known method can be applied to apply the water-soluble or organic acid water-soluble temporary fixing material film 2. In general, spray coating and roll coating are well known methods. The adjustment of the thickness of the film 2 is controlled by the concentration of the liquid, the coating temperature, the coating speed, etc., and the coating thickness is preferably 1/10 to 2/3 of the average grain diameter.

  Next, as shown in FIG. 2B, abrasive grains 31 to 33 are embedded in the water-soluble or organic acid water-soluble film 2. The material of the abrasive grains may be selected according to the relationship between the object to be polished and the polishing performance of the abrasive grains. Inorganic particles such as alumina, silica, diamond, boron nitride, silicon carbide, crosslinked acrylic resin, crosslinked polystyrene resin, melamine resin Organic particles such as can be employed.

To embed the abrasive grains to the water-soluble or organic acid water-soluble film 2 as a single particle layer is electrostatically charging the abrasive grains, and electrostatic spraying to a temporary substrate 1 to the ground potential is suitable. The electrostatic spraying referred to here is performed using the apparatus shown in FIG.

FIG. 3 is a schematic view of a spraying device for electrostatically spraying abrasive grains, and is composed of an abrasive supply unit 10 and a spraying unit 20. The abrasive grains are supplied from the supply hopper 12 to the abrasive grain adjustment chamber 11, and the abrasive grains are charged to the same polarity, positive or negative, in the pressure feeding tube 16. Which polarity is charged depends on the material of the abrasive grains. For example, a negative potential is selected when the abrasive is diamond, and a positive potential is selected when the abrasive is alumina.

The charge amount of the abrasive grains is detected by the charge sensor 15, and the abrasive grain supply amount is controlled by the abrasive grain amount control box 13 so that the charge amount becomes an appropriate value. The abrasive grains whose supply amount is controlled are sprayed from the spray nozzle 21 toward the substrate stage 22 via the pressure feed tube 16. This inside wall of the case the electrostatic spraying device is to charge the abrasive grains of the same polarity, the abrasive grains are subjected to repulsive force from the inner wall, efficiently reach the Karimoto material 1 without adhering to the inner wall of the container.

  In addition, as a method for promoting friction with the inner wall of the pressure feed pipe, in order to prevent pressure loss in the pressure feed pipe, (a) a function of supplying a supply gas (dry air, nitrogen gas, etc.) is added in the middle of the pressure feed pipe. , (B) a mechanism for making the inside of the pressure feed pipe negative pressure, and (c) a method of adding a plurality of branch pressure feed pipes to increase the friction efficiency.

  Next, the charged particles guided to the spray nozzle 21 of the spray chamber 20 are sprayed with the charged abrasive particles together with the compressed gas discharged from the spray nozzle arranged around the spray nozzle 21. As the compressed gas, ordinary compressed cylinder gas is used, and dry air, nitrogen gas, or the like is used.

Temporary substrate 1 film 2 or organic acid soluble film 2 of the water-soluble is applied is placed on a substrate stage 22, and the potential of the temporary substrate 1 is kept at ground potential. The abrasive particles sprayed from the spray nozzle 21 are charged with a potential of the same polarity of 1 to 50 kV. Therefore, the individual abrasive grains fly on the water-soluble film 2 or the organic acid water-soluble film 2 on the temporary base material 1 in the state where the aggregation is released by receiving the electrostatic repulsive force. In this case, since the inner wall of the electrostatic spraying chamber 20 is kept at the same polarity as the abrasive grains, the abrasive particles sprayed from the spray nozzle 21 do not adhere to the inner wall of the chamber, and the water-soluble film 2 or organic acid can be obtained with a high yield. Fly over the water-soluble membrane 2.

Also is important here is Karimoto material 1, it is to turn the film 2 or organic acid soluble film 2 of the water-soluble is maintained at ground potential. Since the abrasive grains have the same polarity, the abrasive grains are strongly and electrically attracted toward the water-soluble film 2 or the organic acid water-soluble film 2 kept at the ground potential, and have a large kinetic energy. Or it collides with the organic acid water-soluble film.

Since the water-soluble film 2 or the organic acid water-soluble film 2 has a soft property, abrasive grains having a large kinetic energy easily bite into the water-soluble film 2 or the organic acid water-soluble film 2 as shown in FIG. As shown in b), the front end abuts on the temporary substrate 1 and is aligned.

  If the potential showing such an effect is 1 kV or more, the effect is remarkable. Although the effect is maintained even at 50 kV or more, since it may be difficult to create a device in reality, the present invention is limited to a potential range of 1 to 50 kV.

Compared with the conventional method of spraying abrasive grains in the present invention, in the conventional example, the force for attracting abrasive grains strongly does not work toward the temporary base material on which the abrasive grains are temporarily fixed. For example, if the particles are simply dropped by gravity, the abrasive grains only adhere to the surface of the temporary fixing material, and cannot pass through the temporary fixing material and reach the temporary base material .

  In addition, in the present invention, since each abrasive grain is charged to the same polarity, when it reaches the water-soluble film 2 or the organic acid water-soluble film 2, they repel each other and do not cause new aggregation. . That is, it is temporarily fixed in the film 2 of the temporary fixing material by a single particle layer.

  Further, since the abrasive grains that have reached the water-soluble film 2 or the organic acid water-soluble film 2 are temporarily fixed while being charged to the same polarity, they are fixed while being separated from each other when viewed in the plane direction. Therefore, there is also a feature that a polishing sheet can be obtained while maintaining a distance between abrasive grains effective for effective discharge of polishing residues.

  By performing electrostatic spraying on the water-soluble film or organic acid water-soluble film in this way, a single particle layer polishing sheet in which the cutting edges are finally aligned and the abrasive grains are spaced apart in the plane direction as shown in FIG. 2h. Can be realized.

  The thickness of the water-soluble film 2 or the organic acid water-soluble film 2 is determined in relation to the size of the abrasive grains, and is preferably 1/10 to 2/3 of the average grain diameter of the abrasive grains. The reason for this is to cover 9/10 to 1/3 of the abrasive grains with the adhesive resin 5 in the next step, as shown in FIG.

  In addition, since conventional abrasive grains have been classified by cutting both fine grains and large grains so that the grain size is distributed in a narrow range in order to form a single grain layer, they have become expensive abrasive grains. In the present invention, even if a large particle is contained, it only protrudes from the water-soluble film or the organic acid water-soluble film, and the protruding part is covered with the adhesive resin 5, so there is no problem. The fine particles are buried in the water-soluble film 2 or the organic acid water-soluble film 2 so that the cutting blade does not appear, so it is necessary to cut the fine particles. However, in the present invention, the classification operation can be performed by cutting only the fine particles. Is also advantageous.

Separately from the electrostatic spraying of the abrasive grains, a base material 4 coated with the adhesive resin 5 shown in FIG. 2C is prepared. This is a base material 4 as a final product, and an acrylic resin mainly composed of polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyolefin resins such as polyethylene and polypropylene, polystyrene, vinyl chloride, polyvinyl alcohol or methacryl alcohol. Resins such as resin and polycarbonate are employed.

The thickness of the substrate 4 is not particularly limited, but is desirably in the range of 5 to 100 microns, preferably in the range of 10 to 75 microns. The base material 4 is coated with an adhesive resin 5 that plays a role of fixing the abrasive grains in the final product.

As the adhesive resin 5, a generally adopted UV curable resin or thermosetting resin is applied. In particular, a UV curable resin is preferable because it can be easily cured as described below.

The base material 4 prepared in FIG. 2C is pressed so that the adhesive resin 5 is in contact with the abrasive grains 31 to 33 and is pressed by using a method such as a calendar roll. By this operation, the protruding portions of the abrasive grains 31 to 33 which are not in contact with the water-soluble film 2 of the abrasive grains or the organic acid water-soluble film 2 bite into the adhesive resin 5 and are firmly held through the curing process. Become.

Next, the curing of the adhesive resin 5 will be described. Figure 2 (e) is shown a case where the base material 4 is polyethylene terephthalate illustrating a UV light transmitting, but curing of the adhesive UV resin 5 UV light 6 from the back surface is irradiated is completed. Of course, when using an adhesive resin that does not transmit UV light, the effect can be completed by applying predetermined heat drying.

Since the water-soluble film 2 or the organic acid water-soluble film 2 is not cured at the curing stage of the adhesive resin 5, the temporary substrate 1 is peeled off or the water-soluble film 2 or the organic acid water-soluble film at the next stage. The removal of the film 2 is easy. If, for example, an epoxy thermosetting resin with strong adhesive strength is used instead of the water-soluble film 2 or the organic acid water-soluble film 2, the curable resin simultaneously cures when the adhesive resin 5 is cured. since receiving, peeling of the adhesive resin 5 and Karimoto material 1 becomes difficult. Further, the abrasive cutting blade is also covered with the curable resin, and the cutting blade does not come out. Therefore, it can be understood that the use of a water-soluble or organic acid water-soluble material as the material of the temporary fixing material film 2 is an important novel point of the present invention.

Bonding the temporary substrate 1 and the curing is completed the resin 5 is stripped and then the film 2 of 2 or organic acid-soluble water-soluble film, water or organic acid solution is injected. In the case of the membrane 2 such as chitin or chitosan, the membrane 2 is easily removed by spraying so-called vinegar. In the case of polysaccharides, glue, and starch, the film 2 is removed by spraying water, and the cutting blade is exposed. The abrasive sheet thus obtained has a single particle layer and the cutting edges are aligned, there is no agglomeration as shown in FIG. 2 (h), and the aligned cutting edges are in contact with the object to be polished 8, so there is no scratch. In addition, efficient polishing can be performed. Examples are shown below.

(1) Adjustment of polishing abrasive grains Diamond abrasive grains having an average diameter of 10 microns were used, and fine particles of approximately 2 microns or less were removed with a cyclone classifier. Although many agglomerations were observed by microscopic observation after classification, the abrasive grains were used for the test as they were.

(2) was prepared good polyethylene terephthalate film smoothness in the thickness 50 microns preparation temporary substrate of the temporary substrate. When the surface roughness was measured in advance with a stylus type surface roughness meter, the average surface roughness Ra was 0.4 microns. In order to form a temporary fixing material film on the film, (A) a chitosan solution (B) a 10% aqueous solution of polyvinyl alcohol having a degree of polymerization of about 200 and (C) a solution obtained by dissolving corn starch, which is a kind of starch, in water Each was applied to obtain three types. The coating was spray type, and the coating thickness and the thickness data measured with an indentation type weight meter were stacked to adjust the coating thickness so that the thickness was in the range of 3 to 5 microns.

(3) Dispersion of abrasive grains The diamond abrasive grains classified as described above were electrostatically dispersed. The spray nozzle diameter was set to 5 mm, and the carrier gas was discharged at 3 kg / cm ² for 5 seconds, and this discharge was repeated 10 times. The charging voltage at this time was 5 kV.

(4) Preparation and welding of the base material, the base material of polyethylene terephthalate cured thickness 75 microns was applied an epoxy based UV resin as an adhesive resin. The coating thickness was not particularly limited, but about 10 to 15 microns was selected. The base material was applied and pressed so that the UV adhesive resin was in contact with the abrasive grains electrostatically sprayed onto the temporary fixing material film. Thereafter, UV light was irradiated at a distance of 100 mm from the polyethylene terephthalate substrate side to completely cure the UV resin as the adhesive resin.

(5) the temporary substrate was peeled off Karimoto material after removal UV irradiation of the temporary fixing material. Peeling was possible using tweezers. After peeling, the surface was found to remain temporarily fixed and dissolved with water or acid. When the temporary fixing material was chitosan, commercially available vinegar was sprayed for 20 minutes. In the case of a 10% aqueous solution of polyvinyl alcohol having a polymerization degree of 200, water heated to about 60 ° C. was sprayed. In the case of corn starch liquid, the removal of the temporary fixing material was completed by spraying tap water at room temperature for 5 minutes to such an extent that the appearance of these temporary fixing materials was not recognized.

(6) Evaluation method The state of abrasive grain adhesion after the above series of steps was observed with a microscope. FIG. 4 is a photograph obtained by observing, with a microscope, a state in which the diamond abrasive grains are dispersed in a film of a 10% aqueous solution of polyvinyl alcohol by the electrostatic spraying method. The portion that appears white in the figure is diamond abrasive grains, and as can be seen from the results, no aggregation is observed in each abrasive grain, and it is understood that the abrasive grain layer is formed of a single grain layer. Further, it can be seen that the diamond abrasive grains are separated from each other when viewed in the plane direction, and are in a state useful for discharging polishing residues.

Test of polishing performance we row bearings ball machining test, the polishing amount of a certain time, were compared for the center line surface roughness (Ra) and maximum surface roughness (Rmax).

  The performance test of the polishing tape was performed with a processing test polishing apparatus (bearing ball processing tester) shown in FIG. 5 using a steel ball (SUJ-2) of a ball bearing (ball bearing) as a test piece and a diameter of 4 mm.

  The processing test apparatus 40 has a polishing sheet 43 of the present invention attached on a rotatable surface plate 42, the steel balls 44 are fixed to a jig 45 as processing test pieces, and an upper part of the polishing head 42 installed on the main shaft 46. A specified load 47 is applied.

In the processing test, the surface plate 42 with the polishing sheet 43 attached is rotated, and the polishing head 41 with the steel balls 44 fixed is brought into contact with the surface of the polishing sheet 43 attached on the surface plate 42 with a constant load. Polishing was performed by moving the platen 42 from the center to the outer periphery at a constant speed and a constant distance. Note that the processing of the test piece is automatically started and finished by moving the arm 48 supported by the fulcrum 49 up and down. After the processing, the steel ball 44 was removed from the jig 44 and weighed to reduce the weight of the steel ball 44 as the polishing amount. The polishing test was evaluated by averaging five steel balls.
The processing conditions are shown below.

(6-1) Load: 500 g
(6-2) Surface plate diameter: 8 inches (6-3) Surface plate rotation speed: 300 rpm
(6-4) Movement distance from the center to the outer periphery: 100 mm
(6-5) Polishing time: 12 seconds

On the other hand, the average surface roughness Ra and the maximum height Rmax of the polished surface of the steel ball after polishing were measured with a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd., SURFCON 480A ) .

(Comparative example)
As a comparative example, the same UV resin as in the above example was applied on a polyethylene terephthalate film having a thickness of 50 microns, and diamond abrasive grains having an average diameter of 10 microns were directly sprayed thereon. For spraying, the abrasive grains were ejected from the fine holes at an air pressure of 1 kg / mm ² and allowed to fall naturally. Thereafter, the UV resin was cured under the same conditions as in the examples to obtain an abrasive sheet.

(7) Evaluation results The evaluation results of the examples and comparative examples are shown in Table 1 below.

In the comparative example, many scratches were observed, but only one or two shallow scratches were observed in the examples. The polishing sheet of this example is useful as an abrasive that does not cause polishing scratches and can efficiently perform polishing with good surface roughness. In particular, a polishing sheet in which abrasive grains are separated from each other when viewed in a planar direction by using a water-soluble or organic acid water-soluble material as a temporary fixing material, and simultaneously charging the abrasive grains to the same polarity and keeping the temporary base material at the ground potential. Is obtained. Further, it has been found that the cutting blades are completely exposed and aligned, and as a result, the polishing sheet exhibits extremely good polishing performance.

The partial sectional view of the polish sheet concerning the present invention. (A)-(h) is schematic which shows the manufacturing process of the polishing sheet which concerns on this invention . Schematic which shows the electrostatic spraying apparatus of the abrasive grain in this invention. The photograph figure which shows distribution of the abrasive grain after the abrasive grain distribution in this invention. The schematic perspective view of the test piece processing apparatus which uses the abrasive sheet which concerns on this invention.

1: temporary substrate 2: provisional fixing material layer (film)
4: Base material 5: Adhesive resin 6: UV light 8: Object to be polished

Claims (7)

A method for producing a polishing sheet in which a single layer of abrasive grains fixed by an adhesive on a substrate exposes a portion of the adhesive that abuts on the object to be polished and aligns the tips thereof on the same plane. And
A first step of forming a temporary adhering material film having a thickness smaller than the average particle diameter of the abrasive grains on the temporary base material;
A second step of dispersing the abrasive grains on the temporary fixing material film so as to be in contact with the temporary base material;
A third step of press-contacting the base material coated with the adhesive with the adhesive facing the abrasive grains;
A fourth step of curing the pressure-bonded adhesive;
And after the adhesive is cured, a fifth step of peeling the temporary base material and further removing the temporary fixing material film,
In the second step, the abrasive grains whose supply amount is controlled are electrostatically charged to the same polarity by pressure feeding, and the temporary fixing material of the temporary base material in which the electrostatically charged abrasive grains are set to the ground potential. It is sprayed film, spraying the electrostatically charged abrasive grain layer of the temporary fixing material, inside wall of the spraying device is charged with the abrasive grains of the same polarity, of the abrasive sheet, characterized in that Production method.   The method for producing a polishing sheet according to claim 1, wherein the thickness of the film of the temporary fixing material is in a range of 1/10 to 2/3 of an average particle diameter of the abrasive grains. Wherein the temporary substrate as a ground potential, by spraying the abrasive grains are electrostatically charged to the same polarity to the membrane of the temporary fixing material on said temporary substrate, together with the abrasive grains are separated from each other The method for producing an abrasive sheet according to claim 1, wherein the method is in contact with a temporary base material.   The method for producing an abrasive sheet according to claim 3, wherein the potential charged to the same polarity of the abrasive grains is in the range of 1 to 50 kV.   The method for producing an abrasive sheet according to any one of claims 1 to 4, wherein the temporary fixing material film formed on the temporary base material is a water-soluble or organic acid water-soluble film. .   6. The method for producing an abrasive sheet according to claim 5, wherein the water-soluble or organic acid water-soluble film is a polysaccharide, glue, starch, chitin, or chitosan. The method for producing an abrasive sheet according to claim 6, wherein the water-soluble film is glycogen, cellulose , dextran, dextrin, polyvinyl alcohol, or starch produced from a plant.