JP2005288645A - Grinding/polishing tool with fixed abrasive grains - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding/polishing tool with fixed abrasive grains assuring excellent surface flatness on a ground workpiece while it can exert an excellent grinding performance. <P>SOLUTION: The invention relates to the grinding/polishing tool with fixed abrasive grains containing plate-form particles in which cerium oxide particles having the mean particle size in the plate surface direction as ranging between 10-200 nm are bound together by a water soluble high-polymer substance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixed abrasive grinding / polishing tool for grinding or polishing a workpiece, and particularly to a fixed abrasive grinding / polishing tool using predetermined cerium oxide particles as main abrasive grains.

  There is a strong need for thinning silicon wafers, and thinning is performed by various methods. Grinding stones using diamond abrasive grains are widely used due to their high grinding efficiency. However, while grinding efficiency is high, grinding marks remain on the workpiece, and different grinding slurry grains are used to remove the grinding marks. At present, mirror finishing must be performed by grinding means. That is, it is necessary to perform grinding by a completely different method, and the grinding process becomes complicated. As a result, there is a problem that the grinding efficiency is lowered and the grinding cost is increased.

  On the other hand, in the grinding method using slurry abrasive grains, although good surface smoothness can be obtained after grinding, there is a problem that the grinding speed is slow and the grinding efficiency is low.

  In addition, for the thinning of quartz wafers, a slurry in which cerium oxide particles having a size of about 1 μm are dispersed is usually used. However, further improvement in grinding efficiency is required and waste generated in large quantities. Slurry processing is becoming a major environmental problem.

  Despite the need for further improvement in grinding efficiency, fixed abrasive grinding that still meets market needs due to the essential problem of increasing surface efficiency after grinding. At present, polishing tools have not been developed.

  On the other hand, Patent Document 1 describes active abrasive grains capable of grinding a workpiece by mechanochemical action, and a grindstone using the active abrasive grains. This was developed by one of the inventors of the present invention and uses a liquid in which glass beads and a water-soluble polymer binder such as sodium alginate are mixed and processed into a predetermined state using electrophoresis. This is what makes a grindstone. There are active abrasive grains that make up a grindstone that exhibit excellent grindability due to mechanochemical action, and that even if the grinding method using this grindstone is grinding, excellent mirror surface creation can be realized. Has been described.

  Furthermore, Patent Document 2 and Patent Document 3 describe cerium oxide particles having a plate shape and an average particle diameter in the plate surface direction of 10 to 200 nm. This was developed by one of the inventors of the present invention, and is obtained by synthesizing cerium oxide particles by the method described in Patent Documents 2 and 3.

JP 2003-73656 A JP 2003-049158 A JP 2003-206475 A

  As described above, the conventional fixed abrasive grinding / polishing tool generally has high grinding efficiency, but has a problem that the surface of the object to be ground is easily damaged and the smoothness of the ground surface is poor. On the other hand, the wet-type slurry abrasive grains are easy to obtain a smooth ground surface, but have the disadvantage that the grinding efficiency is low and the grinding efficiency is poor. At present, no fixed abrasive grinding / polishing tool has been provided which has excellent grindability and can obtain excellent surface smoothness in a workpiece after grinding.

  Therefore, the present invention uses cerium oxide particles having a specific shape and particle size as abrasive grains, and maintains the excellent grindability of a grinding wheel by binding the cerium oxide particles with a water-soluble polymer. However, an object of the present invention is to provide a fixed abrasive grinding / polishing tool capable of simultaneously realizing excellent surface smoothness after grinding, which cannot be obtained with a conventional grinding wheel.

  The present inventors have developed a cerium oxide particle developed by one of the present inventors and having a plate shape and an average particle diameter in the plate surface direction of 10 to 200 nm (Patent Document 2, Patent Document). It has been found that when 3) is used as abrasive grains in the above-mentioned fixed abrasive grinding / polishing tool, excellent grinding performance that cannot be obtained with this type of conventional tool can be exhibited.

  That is, when the particle diameter of the abrasive grains is reduced, the surface smoothness of the ground surface is improved, but the grinding efficiency is lowered. On the other hand, the abrasive grains of the present invention are fine particles having an average particle diameter of 10 to 200 nm. Especially when the particles are plate-like, the edges of the plate-like particles are used, even though they are fine particles. Excellent grinding performance. As described above, the present inventors use cerium oxide particles having a unique shape and particle size, which have two contradictory characteristics in grinding wheels, that is, high grinding efficiency and excellent surface smoothness after grinding. This is the first successful implementation.

  The plate-like cerium oxide particles used in the present invention are characterized by not only exhibiting a particularly excellent mechanical grinding action when using the edge portion but also having a large chemical grinding action. The present invention is the first to simultaneously realize excellent mechanical grindability when such a plate shape is used and excellent chemical grindability possessed by cerium oxide.

  Further, in the fixed abrasive grinding / polishing tool of the present invention, the plate-like cerium oxide particles are used as the main constituent particles according to the type of workpiece to be ground or polished and the grinding specifications. An appropriate amount of at least one oxide particle selected from zirconium oxide and iron oxide can be contained simultaneously. In this way, since the mechanical grindability of these plate-like oxide particles is added, the grindability can be further improved as compared with the case where only the plate-like cerium oxide particles are used.

  These plate-like oxide particles are used as abrasive grains, dispersed in a solution of a water-soluble polymer such as sodium alginate, and the water-soluble polymer is bonded to the abrasive grains to remove water and form a specific shape. By shaping, a grinding wheel can be obtained. In addition, those produced using the electrophoretic phenomenon at the time of molding into a specific shape are fixed abrasive grinding and polishing because the plate-like particles are oriented in a specific direction and the edges are easily aligned and the particles are easily packed densely. Excellent performance as a tool for use.

  As described above, the fixed abrasive grinding / polishing tool of the present invention is a grindstone that can simultaneously realize excellent grinding efficiency and surface smoothness when used as a grinding stone for grinding. It can also be used in the presence of water. In this case, there is an advantage that the chemical polishing action of cerium oxide is more emphasized by the presence of water. In the use of this water, even if the amount used is small, the effect is great, and it can be arbitrarily adjusted according to the application and purpose. As described above, the fixed abrasive grinding / polishing tool of the present invention is a tool that can be used in a wide range that can be used as a grinding wheel or in the presence of water depending on the purpose.

  Although the advantages of using plate-like cerium oxide particles have been mainly described, as described above, by using plate-like cerium oxide particles, mechanical grindability using the edge portion appears. However, by using a structure in which the cerium oxide particles having an average particle diameter in the range of 10 nm to 200 nm of the present invention are combined with a water-soluble polymer, chemical grindability by fine particles is emphasized, and the conventional fixed abrasive Exhibits excellent grinding and polishing properties that could not be obtained with a grain grinding and polishing tool. Therefore, the fixed abrasive grinding / polishing tool of the present invention is not limited to the plate-like cerium oxide particles, and cerium oxide particles having an average particle diameter in the range of 10 nm to 200 nm are combined with a water-soluble polymer. Is the biggest feature.

  According to the fixed abrasive grinding / polishing tool of the present invention, the cerium oxide particles as the constituent particles not only exhibit particularly excellent mechanical grindability when the plate-like edge portion is utilized, but also their chemical properties. Excellent chemical grindability based on properties. Moreover, since the particle diameter is as fine as 10 to 200 nm, excellent surface smoothness can be obtained even after the workpiece is ground. In this way, a grindstone capable of simultaneously realizing excellent grinding efficiency and excellent surface smoothness after grinding can be realized. In addition, plate shape said here shows that the ratio of the maximum length and thickness in the plate | board surface direction of a particle exists in the range of 2-20. Such a particle diameter was obtained from an average value of 100 particles photographed using a high-resolution transmission electron microscope. The thickness was determined by applying a paint in which these particles were dispersed in a binder on a sheet and observing the cross section with a high-resolution transmission electron microscope.

  When the cerium oxide particles are the main constituent particles and specific oxide particles such as plate-like aluminum oxide are added in an appropriate amount at the same time, the mechanical grindability of these specific oxide particles is further added. Therefore, the grindability can be further improved as compared with the case where only plate-like cerium oxide particles are used.

  Furthermore, in the production of the grindstone as described above, by using the electrophoresis phenomenon, a fixed abrasive grinding / polishing tool that exhibits more excellent grindability can be obtained.

  The fixed abrasive grinding / polishing tool of the present invention is a water-soluble cerium oxide particle developed uniquely as described above, that is, a cerium oxide particle having a plate shape and an average particle diameter of 10 to 200 nm (10 nm to 200 nm). By using a structure bonded with a polymer, high grinding efficiency and excellent surface smoothness are realized at the same time.

  The particle cerium oxide particles having the specific shape and particle size used in the present invention are obtained by adding an aqueous solution of cerium salt to an alkaline aqueous solution, and then obtaining the obtained cerium hydroxide or hydrate in the presence of water. Can be obtained by heat treatment in the temperature range of 110 to 300 ° C., filtration and drying, and further heat treatment in the temperature range of 200 to 1500 ° C. in the air.

  Specifically, first, as a first step, an aqueous solution of the metal salt described above is added to an alkaline aqueous solution, and the resulting hydroxide or hydrate is heated in the temperature range of 110 to 300 ° C. in the presence of water. The target shape and particle size are adjusted by hydrothermal reaction treatment.

  In this case, since the pH that precipitates as a hydroxide or hydrate varies depending on the type of metal, control of the pH is important. For example, since aluminum hydroxide or hydrate does not dissolve and precipitate in both the acidic region and the alkaline region, it is necessary to control the pH in a region close to neutrality. On the other hand, cerium hydroxide or hydrate does not dissolve and precipitate in the neutral region, so the pH needs to be controlled in the alkaline region. Moreover, in order to obtain a hydroxide or hydrate having a desired shape and particle size by hydrothermal reaction, pH control during hydrothermal reaction is also an important factor.

  Next, as a second step, the hydroxide or hydrate is heated in air. As a result, cerium oxide particles having a plate shape and an average particle size in the range of 10 nm to 200 nm, a uniform particle size distribution, extremely little sintering and aggregation, and good crystallinity can be obtained.

  In this way, basically through a two-stage manufacturing process, the cerium oxide has a plate shape and an average particle diameter in the range of 10 nm to 200 nm, which is impossible with conventional manufacturing methods. The particle has been successfully developed.

  The fixed abrasive grinding / polishing tool of the present invention disperses the plate-like cerium oxide particles obtained as described above in a water-soluble polymer solution, and the plate-like cerium oxide particles are made of a water-soluble polymer. It is made by bonding. The water-soluble polymer is not particularly limited, but sodium alginate or polyvinyl alcohol can be used as a preferable polymer. Among them, sodium alginate is a substance contained in seaweed and is particularly preferable as a harmless polymer binder.

  Since the fixed abrasive grinding / polishing tool of the present invention uses a water-soluble polymer as a binder, it has an advantage of reducing the load on the environment in the manufacturing process. However, it is needless to say that various polymer binders that are soluble in an organic solvent can be used for producing a grinding wheel that is an object of the present invention. For example, various polymer binders such as vinyl chloride, polyurethane, and nitrocellulose can be used.

  The cerium oxide particles used in the present invention have a large chemical polishing action as well as a mechanical polishing action. However, depending on the purpose, the cerium oxide particles may be used as main constituent particles to further form plate-like oxidation. When aluminum, zirconium oxide and iron oxide are contained, excellent mechanical grindability of these particles can be added.

  Specifically, the fixed abrasive grinding / polishing tool of the present invention can be produced as follows.

  First, a solution in which a predetermined amount of water-soluble polymer is dissolved is prepared, and a predetermined amount of the above plate-like oxide particles is dispersed in this solution. The dispersion method is not particularly limited, but a uniform dispersion is produced using a ball mill, a paint conditioner or the like.

  The content of the water-soluble polymer in the fixed abrasive grinding / polishing tool is preferably in the range of 0.5 to 30% by weight, more preferably 1 to 25% by weight, and further preferably 2 to 20% by weight. is there. When this content is low, the binding ability of the plate-like particles is lowered, and the particles are likely to fall off during grinding. On the other hand, when the amount is too large, the viscosity of the dispersion becomes high, and it becomes difficult to uniformly disperse the particles.

  On the other hand, the content of the oxide particles is preferably in the range of 50 to 99% by weight, more preferably 60 to 97% by weight, and still more preferably 75 to 95% by weight. If the content is less than this range, the grinding efficiency is lowered. On the other hand, if the content is too large, the binding property to the polymer is lowered, and the abrasive grains easily fall off during grinding.

  Although the dispersion obtained as described above can be used as a slurry grindstone, it is preferable to form the dispersion into a specific shape while utilizing the electrophoresis phenomenon. The electrophoresis method is not particularly limited. For example, the electrophoresis can be performed using an apparatus in which a cylindrical positive electrode rod is placed near the center of the electrophoresis tank and a negative electrode is installed so as to surround the periphery. That is, by placing the above-mentioned dispersion in the electrophoresis tank and applying a voltage between the positive and negative electrodes while rotating the positive electrode rod, the plate-like oxide particles covered with the water-soluble polymer are positive electrode Precipitates while adsorbing to the rod. When the plate-like oxide particles of the present invention are adsorbed and precipitated by using such electrophoresis, the plate-like particles have the advantage that they are easily arranged so that the plate surface is parallel to the positive electrode rod. By arranging in this way, the edge surfaces of the plate-like particles are easily aligned in a specific direction, so that the grinding efficiency is further improved when used as a fixed abrasive grinding tool.

  Next, the positive electrode rod is pulled up from the dispersion, and the positive electrode rod is removed from the molded body made of plate-like oxide particles and a water-soluble polymer, thereby forming a molded body having a predetermined shape (in this example, around the positive electrode having a round bar shape). Thus, a substantially cylindrical shaped body corresponding to the shape of the positive electrode rod is obtained. By cutting this molded body into an arbitrary size and drying in the air, the final target tool can be obtained.

  In the above example, a case where a cylindrical molded body is produced using an electrophoresis phenomenon has been shown, but by changing the shape of the electrode and the molded shape, an arbitrary shape such as a disk shape or a prismatic shape, It goes without saying that a grinding wheel of a size can be produced. Furthermore, the use of electrophoretic phenomenon is one of the effective methods for making a high-filled grindstone with plate-like oxide particles. It is also possible to produce it. The method of producing only by press molding has an advantage that the manufacturing process is simplified.

  The fixed abrasive grinding / polishing tool of the present invention can simultaneously achieve excellent grinding efficiency and surface smoothness when used as a grinding wheel for grinding, but it can also be used in the presence of water. In this case, the chemical polishing action of cerium oxide caused by the presence of water can be arbitrarily adjusted by adjusting the amount of water used. Thus, the fixed abrasive polishing tool of the present invention can be used as a grinding wheel or in the presence of water depending on the application and purpose. That is, it can be said that it is a fixed abrasive grinding / polishing tool with a wide range of use that can be used in various modes.

  Further, by using cerium oxide particles in this way, especially in the case of a plate-like shape, mechanical grindability using an edge portion appears, but the average particle diameter of the present invention is in the range of 10 nm to 200 nm. Even if the particles are combined with a water-soluble polymer, chemical grindability is emphasized because of the small particle size, and excellent grinding and polishing that cannot be obtained with conventional fixed abrasive grinding tools. Demonstrate sex.

  Hereinafter, the main production method of the present invention will be described in more detail. In particular, when the plate-like cerium oxide particles are used, the effect of the present invention is more exhibited. Therefore, an example using the plate-like cerium oxide particles will be described. As described above, the present invention has an average particle diameter of 10 nm to 200 nm. Even with a structure in which cerium oxide particles in the range are combined with a water-soluble polymer, the chemical grindability is emphasized and excellent grinding that cannot be obtained with conventional fixed abrasive grinding tools Exhibits abrasiveness.

<Production of plate-like cerium oxide particles, etc.>
(Preparation of precipitate)
First, a cerium salt such as cerium chloride, cerium nitrate, and cerium sulfate is dissolved in water to prepare a water solution (cerium salt aqueous solution) containing cerium ions. Of these cerium salts, cerium chloride is most preferred for obtaining cerium oxide particles having a sharp particle size distribution. As the alkali, sodium hydroxide, potassium hydroxide, lithium hydroxide, aqueous ammonia solution or the like can be preferably used.

  Next, the cerium salt aqueous solution is dropped into an alkaline aqueous solution to form a cerium hydroxide or hydrate precipitate. The pH of the suspension containing the precipitate is preferably adjusted to a range of 8 to 11, and the suspension is preferably aged at room temperature for about 1 day. This pH adjustment and aging are effective in obtaining cerium oxide particles having higher crystallinity at a relatively low temperature in the heat treatment in the subsequent step.

(Hydrothermal treatment)
Hydrothermal treatment is performed on the suspension containing the above precipitate of cerium hydroxide or hydrate using an autoclave or the like. In this hydrothermal treatment, the suspension containing the precipitate may be subjected to hydrothermal treatment as it is, but products and residues other than the precipitate are removed by washing with water, and then the pH is adjusted again with NaOH or the like. It is preferable to do. The pH value at this time is preferably 7 to 11, and if it is lower than this pH, crystal growth becomes insufficient during hydrothermal treatment. It may be difficult to obtain particles having a small particle size.

  The hydrothermal treatment temperature is preferably in the range of 110 ° C to 300 ° C. If the temperature is lower than this temperature, it is difficult to obtain a cerium hydroxide or hydrate having a plate-like shape. If the temperature is higher than this temperature, the generated pressure becomes high, so that the apparatus becomes expensive and has no merit.

  The hydrothermal treatment time is preferably in the range of 1 hour to 4 hours. If the hydrothermal treatment time is too short, the growth to a specific shape becomes insufficient, and even if the hydrothermal time is too long, there is no particular problem, but only the production cost becomes high and is meaningless.

(Heat treatment)
The cerium hydroxide or hydrate particles after hydrothermal treatment are filtered and dried, and then heat-treated. Before filtration, the pH is adjusted to a neutral region around 6 to 9 by washing with water. It is preferable to keep it. This is because, by washing with water up to this pH, impurities such as sodium and chlorine that have adverse effects such as sintering are removed in the heat treatment step.

  Silica treatment may be performed by adding a silicon compound such as sodium silicate to cerium hydroxide or hydrate particles. This silica treatment is effective in maintaining the final target cerium oxide particles in a specific shape.

  The filtered or dried cerium hydroxide or hydrate can be converted into cerium oxide particles by heat treatment. The atmosphere during the heat treatment is not particularly limited, but heating in air is preferable because it is the least expensive to manufacture. The heat treatment temperature is preferably in the range of 300 ° C to 1200 ° C. If it is lower than this temperature, crystalline cerium oxide fine particles are difficult to be obtained, and if it is too high, the particle size becomes larger due to sintering or the particle size distribution becomes wider. By this heat treatment, cerium oxide particles are obtained. However, if unreacted substances are removed by washing with water or the like, higher-purity cerium oxide particles are obtained. It is preferable to do.

The cerium oxide particles thus obtained are particles having a plate-like shape with a particle diameter in the range of 10 nm to 200 nm, and are optimum particles for a fixed abrasive grinding tool. When the X-ray diffraction spectrum of this cerium oxide particle is measured, a peak corresponding to the crystal structure of CeO ₂ having a CaF ₂ structure is clearly observed, and a crystal wall is also clearly observed in an electron microscope. It was shown that it was a plate-like particle having extremely good crystallinity that could not be obtained by the above production method.

  The method for producing plate-like cerium oxide particles has been described as an example, but plate-like aluminum oxide, plate-like zirconium oxide, and plate-like iron oxide were also developed by one of the inventors of the present invention (Patent Document 2, According to Patent Document 3), it can be produced by the same method.

《Adjustment of dispersion for fixed abrasive grinding tool》
An example of a dispersion adjusting method for producing a fixed abrasive grinding / polishing tool using the cerium oxide particles produced by the method described above will be described below.

  Sodium alginate was dissolved in a predetermined amount of water. The amount of sodium alginate added at this time is suitably 0.1 to 2% by weight with respect to water. When the addition amount is less than this range, it becomes difficult to uniformly disperse the cerium oxide particles, and the cerium oxide particles tend to settle. On the other hand, when the addition amount is larger than this range, the viscosity becomes high, and the dispersibility when dispersing the cerium oxide particles is deteriorated.

  Next, cerium oxide particles are added and dispersed in this aqueous sodium alginate solution. The addition amount of the cerium oxide particles is suitably 1 to 20% by weight with respect to water. If the amount added is less than this range, it will be difficult to obtain high polishing efficiency when a fixed abrasive grinding tool is used, and if the amount added is more than this range, it will be difficult to uniformly disperse the cerium oxide particles, resulting in uniform dispersion. It becomes difficult to get a body.

  The dispersion method is not particularly limited, and various dispersers such as a ball mill, a paint conditioner, and a disper can be used. Among them, a paint conditioner can be used as a suitable disperser. The dispersion time varies depending on the dispersion apparatus to be used. For example, when a paint conditioner is used, 1 to 10 hours is appropriate.

  Next, the dispersion is placed on a hot plate, and the dispersion is heated while stirring to evaporate water and concentrate the dispersion. The weight after evaporation and concentration is preferably 1/2 to 1/10 of the weight before evaporation. When the degree of concentration is less than this range, the filling property of the cerium oxide particles becomes low or the cerium oxide particles in the dispersion liquid are liable to settle during the production of a molded body using the electrophoresis phenomenon described later. On the other hand, when the amount is larger than this range, it becomes difficult to move the cerium oxide particles due to the electrophoretic phenomenon, resulting in a reduction in the efficiency of forming the molded body.

  When the content of sodium alginate and cerium oxide particles in the dispersion after evaporation and concentration is 0.2 to 5% by weight and 2 to 60% by weight, the efficiency at the time of forming a molded body using the electrophoresis phenomenon is improved. In addition, the grindability as a fixed abrasive grinding tool produced using this molded body, the retention of cerium oxide particles, and the like are the most balanced.

<< Preparation of molded body of cerium oxide / water-soluble polymer mixture using electrophoresis >>
The dispersion liquid evaporated and concentrated as described above was placed in a glass beaker, and a metal negative electrode was spirally arranged so as to surround the metal positive electrode rod. A DC voltage was applied to both the positive and negative electrodes while rotating the positive electrode rod. The applied voltage varies depending on the size, shape and interval of the positive and negative electrodes, but is preferably 1 to 20V. The current at this time is about 0.1 to 3 A, and the cerium oxide particles covered with the water-soluble polymer are electrically attracted and deposited on the positive electrode rod, and the deposition thickness increases with time.

《Preparation of fixed abrasive grinding tool》
After the cerium oxide particles covered with the water-soluble polymer are deposited to an appropriate thickness by the above-described method, the positive electrode rod is pulled up from the dispersion, and further the positive electrode rod is pulled out, and the cylindrical deposit is appropriately removed Cut to height. The cut product was dried in air at room temperature. Furthermore, the periphery of the dried product was polished and smoothed, and finally the target tool was finished.

[Example]
Examples of the present invention and comparative examples will be described below.

<Preparation of plate-like cerium oxide particles>
0.90 mol of sodium hydroxide was dissolved in 800 ml of water to prepare an aqueous alkaline solution. Separately from this alkaline aqueous solution, 0.074 mol of cerium (III) chloride heptahydrate was dissolved in 400 ml of water to prepare an aqueous solution of cerium chloride. The latter aqueous aluminum chloride solution was dropped into the former alkaline aqueous solution to prepare a precipitate containing cerium hydroxide at about 25 ° C. The pH at this time was 10.5. This precipitate was aged in a suspension state for 20 hours.

  Next, after removing the supernatant, the precipitate suspension was charged into an autoclave and hydrothermally treated at 180 ° C. for 2 hours.

  The hydrothermal treatment product was washed with water, filtered and dried in air at 90 ° C. The dried product was lightly crushed with a mortar and then heat-treated at 600 ° C. in air for 1 hour to obtain cerium oxide particles. After the heat treatment, in order to remove unreacted substances and residual substances, they were further washed with an ultrasonic disperser, filtered and dried.

  When the X-ray diffraction spectrum of the obtained cerium oxide particles was measured, a spectrum corresponding to cerium oxide having a fluorite structure was observed. Moreover, when shape observation was performed by 200,000 times using the transmission electron microscope (Hitachi field emission electron microscope HF-200 type | mold), it turned out that an average particle diameter is 21 nm of plate-shaped particle | grains. In addition, the average particle diameter was calculated | required as an average value of the particle diameter of 100 particle | grains on the photographic paper image | photographed with the transmission electron microscope. The ratio of the maximum length and thickness of the particles in the plate surface direction was about 5. The ratio of the maximum length and thickness of the particles in the plate surface direction was determined by cross-sectional observation at 5 million times using the same electron microscope.

  A transmission electron microscope photograph taken at 200,000 times the cerium oxide particles is shown in FIG. 1, and an X-ray diffraction spectrum is shown in FIG.

<Preparation of dispersion using plate-like cerium oxide particles and water-soluble polymer>
3 g of sodium alginate was dissolved in 560 g of water as a water-soluble polymer. To this solution, 37 g of plate-like cerium oxide particles (abrasive grains) prepared by the above-described method was added and dispersed for 2 hours using a paint conditioner. In addition to this mixed solution, 200 g of zirconia beads having a diameter of 1 mm were placed in a pot for paint conditioner as a medium for dispersion treatment. By this dispersion treatment, a dispersion liquid in which individual cerium oxide particles were uniformly dispersed in a sodium alginate aqueous solution was obtained.

Next, the dispersion liquid was taken out from the pot, 300 g of the dispersion liquid was put into a 500 cm ³ glass beaker, and water was evaporated and concentrated until the total weight became 75 g while stirring on a hot plate.

<Preparation of a molded body of plate-like cerium oxide particles / water-soluble polymer mixture using electrophoresis>
The concentrated dispersion described above was transferred to a 100 cm ³ glass beaker, and a positive electrode rod and a negative electrode were set therein. As the positive electrode rod, a brass rod having a diameter of 4 mm and a length of 10 cm was used. As the negative electrode, the same brass rod formed into a spiral shape was used, and this was arranged along the wall surface of the beaker.

  A voltage of 10 V was applied between the positive electrode and the negative electrode using a DC low voltage power source. At this time, the current flowing between the two electrodes was about 0.7 to 0.1 A. In this state, a voltage was applied for 30 minutes while rotating the positive electrode rod, and plate-like cerium oxide particles covered with sodium alginate were deposited on the positive electrode rod. The deposition thickness at this time was about 4 mm, and the diameter was about 12 mm.

<Fabrication of fixed abrasive grinding tool>
The positive electrode rod was extracted from the deposit produced as described above and cut with a cutter knife so that the height was about 1 cm. The cylindrical shaped product was dried in air at room temperature for about 1 day. By drying, a molded body made of a combined body of sodium alginate and plate-like cerium oxide particles having a diameter of about 8 mm and a height of about 7 mm was obtained. The periphery and end face of the molded body were smoothed using a polishing tape or the like to obtain a fixed abrasive grinding / polishing tool.

  In the production of the plate-like cerium oxide particles in Example 1, the hydrothermal treatment condition of the suspension of the precipitate was changed from 180 ° C., 2 hours to 200 ° C., 2 hours, and the heat treatment condition in air was 600 The precipitate containing cerium hydroxide was produced in the same manner as in Example 1 except that the temperature was changed from 1 ° C. to 800 ° C. for 1 hour, washed with water, filtered, dried, heat-treated, and then treated with cerium oxide. Particles were made.

  When an X-ray diffraction spectrum was measured for the obtained cerium oxide particles, a spectrum corresponding to cerium oxide having a fluorite structure was observed as in Example 1. Moreover, when shape observation was performed with the transmission electron microscope, it turned out that it is a plate-shaped particle | grain with an average particle diameter of 58 nm. A transmission electron micrograph taken at 200,000 times the cerium oxide particles is shown in FIG. The ratio of the maximum length and thickness of the particles in the plate surface direction was about 8.

  Using this cerium oxide particle, a dispersion using a water-soluble polymer was prepared in the same manner as in Example 1, and a molded product of a plate-like cerium oxide particle / water-soluble polymer mixture using electrophoresis. To obtain a fixed abrasive grinding / polishing tool.

  In the preparation of the dispersion using the plate-like cerium oxide particles having an average particle diameter of 21 nm and the water-soluble polymer in Example 1, the amount of sodium alginate added as a water-soluble polymer to 560 g of water is changed from 3 g to 1 A dispersion was prepared and concentrated in the same manner as in Example 1 except that the amount was changed to 0.5 g. Furthermore, a molded body of a plate-like cerium oxide particle / water-soluble polymer mixture was produced under the same conditions as in Example 1 to obtain a fixed abrasive grinding / polishing tool.

  In the preparation of the dispersion using the plate-like cerium oxide particles having an average particle diameter of 21 nm and the water-soluble polymer in Example 1, the amount of sodium alginate added as a water-soluble polymer to 560 g of water is changed from 3 g to 4 A dispersion was prepared and concentrated in the same manner as in Example 1 except that the amount was changed to 0.5 g. Furthermore, a molded body of a plate-like cerium oxide particle / water-soluble polymer mixture was produced under the same conditions as in Example 1 to obtain a fixed abrasive grinding / polishing tool.

  In the preparation of the dispersion using the plate-like cerium oxide particles having an average particle diameter of 21 nm and the water-soluble polymer in Example 1, the amount of cerium oxide particles added to 560 g of water was changed from 37 g to 18.5 g. Except for the above, a dispersion was prepared and concentrated in the same manner as in Example 1. Furthermore, a molded body of a plate-like cerium oxide particle / water-soluble polymer mixture was produced under the same conditions as in Example 1 to obtain a fixed abrasive grinding / polishing tool.

  In the preparation of the dispersion using the plate-like cerium oxide particles having an average particle diameter of 58 nm and the water-soluble polymer in Example 2, the amount of sodium alginate added as a water-soluble polymer to 560 g of water was changed from 3 g to 4 A dispersion was prepared and concentrated in the same manner as in Example 2 except that the amount was changed to 0.5 g. Furthermore, a molded body of a plate-like cerium oxide particle / water-soluble polymer mixture was produced under the same conditions as in Example 2 to obtain a fixed abrasive grinding / polishing tool.

  In the preparation of the dispersion using the plate-like cerium oxide particles and the water-soluble polymer in Example 1, 3 g of sodium alginate as a water-soluble polymer was dissolved in 560 g of water, and the resulting solution was used as oxide particles. 29.6 g of cerium oxide particles having an average particle diameter of 58 nm prepared in Example 2, and plate-like aluminum oxide having an average particle diameter of 80 nm and a ratio of the maximum length and thickness in the plate surface direction of about 10 ( 7.4 g of (γ-alumina) particles were added. The latter plate-like aluminum oxide particles are produced by basically the same production method as the plate-like cerium oxide particles described above based on the method developed by one of the inventors of the present invention. The dispersion and the fixed abrasive grinding / polishing tool were produced in the same manner as in Example 1.

  In Example 7, instead of adding 7.4 g of plate-like aluminum oxide particles having an average particle size of 80 nm, the average particle size was 20 nm, and the ratio of the maximum length to the thickness of the particles in the plate surface direction was about 3 A dispersion and a fixed abrasive grinding / polishing tool were produced in the same manner as in Example 7 except that 7.4 g of the plate-like zirconium oxide particles was added. The plate-like zirconium oxide particles are also produced by the same production method as the plate-like cerium oxide particles described above based on the method developed by one of the inventors of the present invention.

  In Example 7, instead of adding 7.4 g of plate-like aluminum oxide particles having an average particle size of 80 nm, the average particle size is 50 nm and the ratio of the maximum length to the thickness of the particles in the plate surface direction is about 5 A dispersion and a fixed abrasive grinding / polishing tool were produced in the same manner as in Example 7 except that 7.4 g of the plate-like iron oxide particles was added. The plate-like iron oxide particles are also produced by the same production method as the plate-like cerium oxide particles described above based on the method developed by one of the inventors of the present invention.

  In the production of the plate-like cerium oxide particles in Example 1, the heat treatment condition in the air was changed from 600 ° C., 1 hour to 300 ° C., 1 hour without hydrothermal treatment of the precipitate suspension. Except that, a cerium hydroxide-containing precipitate was produced in the same manner as in Example 1, washed with water, filtered, dried, and then heat-treated to produce cerium oxide particles. When an X-ray diffraction spectrum was measured for the obtained cerium oxide particles, a spectrum corresponding to cerium oxide having a fluorite structure was observed as in Example 1. Further, when the shape was observed with a transmission electron microscope, it was found that the average particle diameter was 30 nm spherical or granular particles.

  Using this cerium oxide particle, a dispersion using a water-soluble polymer is prepared in the same manner as in Example 1, and further, a spherical or granular cerium oxide particle / water-soluble polymer mixture is formed using electrophoresis. A body was prepared and used as a fixed abrasive grinding / polishing tool.

[Comparative Example 1]
In 260 g of water, 3 g of sodium alginate was dissolved as a water-soluble polymer. To this solution, 37 g of commercially available diamond abrasive grains (average particle diameter: catalog value 0.1 μm) was added and dispersed for 1 hour using a stirrer. This dispersion was placed on a hot plate, and water was heated and evaporated until stirring was not possible.

  This concentrated mixture was formed into a cylindrical shape, dried at room temperature in the same manner as in Example 1, and then the periphery and end face of the formed body were smoothed using a polishing tape or the like to obtain a fixed abrasive grinding / polishing tool. . That is, in this Comparative Example 1, a tool fixed with a water-soluble polymer was prepared using diamond particles as abrasive grains.

[Comparative Example 2]
In 260 g of water, 3 g of sodium alginate was dissolved as a water-soluble polymer. To this solution, 37 g of commercially available α-alumina abrasive grains (average particle diameter: catalog value 0.2 μm) was added and dispersed for 1 hour using a stirrer. This dispersion was placed on a hot plate, and water was heated and evaporated until stirring was not possible.

  This concentrated mixture was formed into a cylindrical shape, dried at room temperature in the same manner as in Example 1, and then the periphery and end face of the formed body were smoothed using a polishing tape or the like to obtain a fixed abrasive grinding / polishing tool. . That is, in Comparative Example 2, a tool was produced in which α-alumina particles were used as abrasive grains and fixed with a water-soluble polymer.

<Evaluation of grindability>
In order to investigate the grinding performance of the fixed abrasive grinding / polishing tools obtained in each of the above Examples and Comparative Examples, the workpiece was actually ground using these tools, and the grindability was evaluated. For the evaluation of grindability, a silicon wafer having a diameter of 4 inches (about 10.16 cm) was used as a workpiece. As an apparatus for examining grindability, a fiber polisher (SFP-120A) manufactured by Seiko Giken Co., Ltd. was used. When grinding, first, four tools prepared by the above-described method are provided along the circumferential portion of the circular metal surface plate (upper surface plate) having a diameter of about 18 cm in the fiber polisher. It fixed using the adhesive agent at equal intervals. On the other hand, a silicon wafer is fixed on a lower surface plate having a diameter of about 12 cm, and an upper surface plate on which the tool is fixed is placed on the upper surface of the silicon wafer. I was able to be pressed against. And the surface of the silicon wafer fixed on the lower surface plate was ground by fixing the upper surface plate and rotating the lower surface plate at 75 rpm.

  Grinding efficiency is determined by placing a diamond-shaped flaw on the silicon wafer surface using an Akashi Knoop hardness tester (HM-122) and examining the amount of decrease in the flaw depth as the grinding proceeds, that is, the grinding depth. Evaluated by. Moreover, the surface smoothness after grinding measured the surface roughness (centerline average roughness) Ra of a silicon wafer using a non-contact surface roughness meter (New View 5000) manufactured by Zygo, and this value (Ra value) It was evaluated from.

  Table 1 shows the types of abrasive grains used in each of the above Examples and Comparative Examples, the average particle diameter, the ratio of added amount, the content of abrasive grains in the grindstone, and the content of water-soluble polymer. The evaluation result of the grinding performed using the tool for fixed abrasive grinding obtained by each example and a comparative example is shown. Note that the grinding depth and the Ra value of the grinding surface shown in Table 2 were measured when grinding was performed for 30 minutes. The greater the grinding depth, the higher the grinding efficiency, and the smaller the Ra value, the better the surface smoothness.

  As is apparent from Table 2, the fixed abrasive grinding / polishing tool using the plate-like cerium oxide particles obtained in Examples 1 to 5 is a grindstone having a good balance between grinding efficiency and surface smoothness after grinding. I know that there is. Despite the fact that the abrasive grains used in this way are fine particles, the excellent grinding efficiency is due to the excellent mechanical grindability utilizing the edge due to the cerium oxide particles being abrasive grains having a plate shape. This is due to the synergistic effect of chemical grindability of the cerium oxide particles. The excellent surface smoothness is based on the fact that the cerium oxide particles, which are abrasive grains, are extremely fine particles with an average particle diameter of 20 nm to 60 nm.

  Moreover, the fixed abrasive grinding / polishing tools of Examples 7 to 9 contain plate-like cerium oxide particles as main constituent particles, and further contain plate-like aluminum oxide particles, plate-like zirconium oxide particles and iron oxide particles. It has been made. These are slightly inferior in surface smoothness to those using only plate-like cerium oxide particles because a silicon wafer was used as the workpiece. The inventors have confirmed that the tools of these examples exhibit excellent grinding performance depending on the type of workpiece to be ground or polished and the grinding conditions. Therefore, it is preferable to select the configuration of the grindstone according to the purpose and application. Furthermore, although the evaluation result in a present Example investigated grindability as a grinding wheel, it is also possible to grind by adding water. Depending on the type of workpiece and the grinding content, grinding conditions can be set arbitrarily, such as dry grinding, water addition grinding, or grinding under high humidity.

  In addition, the fixed abrasive grinding / polishing tool of Example 10 using granular cerium oxide particles is slightly inferior in grindability compared to that using plate-like cerium oxide particles, but the conventional example shown in Comparative Examples 1 and 2 is used. Compared to those using the above abrasive grains, it exhibits a well-balanced grindability.

  On the other hand, the fixed abrasive grinding / polishing tool of Comparative Example 1 using diamond abrasives has high grinding efficiency reflecting the high hardness of diamond particles, but the grinding marks remain clearly after grinding and the surface smoothness is remarkably high. Inferior.

  In the fixed abrasive grinding / polishing tool of Comparative Example 2 using α-alumina particles, relatively good surface smoothness can be obtained, but the grinding efficiency is remarkably low. This is because α-alumina has a relatively high hardness but lacks chemical grindability.

  Thus, the fixed abrasive polishing tool comprising the cerium oxide particles (particularly plate-like cerium oxide particles) of the present invention and a water-soluble polymer simultaneously achieves excellent grinding efficiency and surface smoothness. It can be seen that this is a fixed abrasive grinding / polishing tool having excellent grinding characteristics that cannot be obtained with conventional grinding wheels.

2 is a transmission electron micrograph of 200,000 times the cerium oxide particles obtained in Example 1. FIG. 2 is an X-ray diffraction pattern of cerium oxide particles obtained in Example 1. FIG. 4 is a transmission electron micrograph of 200,000 times the cerium oxide particles obtained in Example 2. FIG.

Claims (11)

  A fixed abrasive grinding / polishing tool for grinding or polishing a workpiece, characterized in that cerium oxide particles having an average particle diameter in the range of 10 nm to 200 nm are bound by a water-soluble polymer. Fixed abrasive grinding and polishing tool.   The fixed abrasive grinding / polishing tool according to claim 1, wherein the shape of the cerium oxide particles is plate-like, and the ratio of the maximum length to the thickness of the particles in the plate surface direction is in the range of 2-20.   A fixed abrasive grinding / polishing tool for grinding or polishing a workpiece, wherein cerium oxide particles having an average particle diameter in the range of 10 nm to 200 nm are main constituent particles, and the average particle diameter is 10 nm to 200 nm. Fixing characterized in that it contains at least one kind of oxide particles selected from zirconium oxide particles, aluminum oxide particles and iron oxide particles in a range, and these particles are bound by a water-soluble polymer. Abrasive grinding tool.   The fixed abrasive grinding / polishing tool according to claim 3, wherein the shape of the cerium oxide particles is plate-like, and the ratio of the maximum length to the thickness of the particles in the plate surface direction is in the range of 2-20.   The shape of at least one kind of oxide particles selected from zirconium oxide particles, aluminum oxide particles and iron oxide particles is plate-like, and the ratio of the maximum length and thickness in the plate surface direction of the particles is 2 to 20 The fixed abrasive grinding / polishing tool according to claim 3 or 4, which is in a range.   The content of at least one kind of oxide particles selected from the zirconium oxide particles, aluminum oxide particles, and iron oxide particles with respect to the cerium oxide particles is in the range of 1 to 50% by weight. The fixed abrasive grinding / polishing tool according to claim 5.   The fixed abrasive grinding / polishing tool is produced by molding into a specific shape using a dispersion in which the plate-like cerium oxide particles are dispersed in a solution in which the water-soluble polymer is dissolved. The fixed abrasive grinding / polishing tool according to claim 1 or 2, wherein the plate-like cerium oxide particles are substantially oriented in a specific direction in the state of the molded body.   The fixed abrasive grinding / polishing tool includes a plate-like cerium oxide particle, a plate-like zirconium oxide particle, an aluminum oxide particle, and an iron oxide particle as the main constituent particles in a solution in which the water-soluble polymer is dissolved. It is produced by molding into a specific shape using a dispersion in which at least one kind of oxide particles selected from the above is dispersed, and the plate-like oxidation in the state of the molded body The fixed abrasive grinding / polishing tool according to any one of claims 3 to 6, wherein the cerium particles and the oxide particles are substantially oriented in a specific direction.   Using a dispersion liquid in which the plate-like cerium oxide particles are dispersed, or using a dispersion liquid in which the plate-like cerium oxide particles and the plate-like oxide particles are dispersed, it is molded into a specific shape. The fixed abrasive grinding / polishing tool according to claim 7 or 8, wherein an electrophoretic phenomenon is used in the step.   The content of the water-soluble polymer is in the range of 0.5 to 30% by weight, and the content of the plate-like cerium oxide particles is in the range of 50 to 99% by weight. The fixed abrasive grinding / polishing tool according to any one of the above.   The content of the water-soluble polymer is in the range of 0.5 to 30% by weight, and is at least selected from cerium oxide particles as the main constituent particles, zirconium oxide particles, aluminum oxide particles, and iron oxide particles. The fixed abrasive grinding / polishing tool according to any one of claims 3, 4, 5, 6, 8, and 9, wherein the content of the oxide particles of one kind is in the range of 50 to 99% by weight.

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