JP2002327171A - Method for producing cerium based polishing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing cerium based polishing agent low in concentration of coarse particles, holding a high polishing force and excellent in cleaning property of the polished face. SOLUTION: This method of production for cerium based polishing agent having a process crushing raw material, a calcination process carrying out a calcinations of the raw material after crushing and a crushing process crushing the calination product, uses a cerium based rare earth carbonate or a mixture of the cerium based rare earth carbonate and the cerium based rare earth oxide and in the crushing process the raw material is crushed in a slurry obtained by mixing the raw material and a solution including a fluorine component to the slurry state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cerium-based abrasive, and more particularly to a method for producing a cerium-based abrasive characterized by a step of pulverizing raw materials before roasting.

[0002]

2. Description of the Related Art Cerium-based abrasives (hereinafter also simply referred to as abrasives) have been widely used for polishing optical lenses, but recently, glass for magnetic recording media such as hard disks and liquid crystal displays (LCD) have been used. It is also widely used as an abrasive for glass materials used in electric and electronic devices such as glass substrates.

A cerium-based abrasive is, for example, calcined at a high temperature in advance from a cerium-based rare earth carbonate (hereinafter, also referred to as a rare earth carbonate) obtained from bastnaesite ore or a complex ore produced in China. The cerium-based rare earth oxide (hereinafter also referred to as rare earth oxide) obtained as a raw material is produced as follows. First, raw materials of these cerium-based abrasives (hereinafter, also simply referred to as raw materials) are wet-pulverized by a pulverizing device such as an attritor, a ball mill, a bead mill, and then subjected to a chemical treatment (wet treatment).
Filter and dry. Thereafter, the raw material particles are appropriately sintered by heating and roasting, and the raw material after sintering is pulverized (re-pulverized) in a dry or wet manner using the above-described pulverizing apparatus. Classify the later raw materials. By doing so, an abrasive having a desired particle size and particle size distribution is obtained.
Here, the chemical treatment refers to a treatment (mineral acid treatment) for removing an alkali metal such as sodium which causes abnormal grain growth during roasting, and a polishing force (polishing speed) of a cerium-based abrasive. This is a treatment (fluorination treatment) in which a fluorine component is added for the purpose of securing or ensuring the smoothness of the polished surface. Since the fluorine component has the effect of improving the smoothness of the surface to be polished and the effect of increasing the polishing force by reacting with the glass as the material to be polished, such effects can be obtained by performing fluorination treatment.

[0004]

However, it is desirable that the abrasive product does not contain coarse particles. This is because the coarse particles cause damage to the polished surface. Also, for example, in the polishing process performed in the manufacturing process of a glass substrate for a magnetic recording medium capable of supporting high-density recording and high-speed reading and writing, extremely high accuracy is required for the smoothness of the surface (polished surface) of the glass substrate. However, it is necessary to meet this requirement. However, if the concentration of coarse particles in the abrasive is high, the surface of the glass substrate is likely to be damaged, and the requirement for smoothness cannot be met. Therefore, also from this point, it is desired that the abrasive does not contain coarse particles.

In view of the efficiency of the polishing operation in the polishing step, it is desirable that the abrasive product has a high abrasive force. Then, in order to secure a high polishing force, it is necessary to grind the abrasive particles so that the particle diameter of the abrasive particles does not become smaller than necessary.

However, the conventional pulverizing means has a limit in satisfying these conditions. In other words, ball mills, attritors, conventional wet pulverization using a pulverizer such as a bead mill, in order to pulverize so as to reduce the coarse particles, it is necessary to increase the pulverization time, but if the pulverization time is increased, more than necessary Since the amount of pulverized fine particles increases, it becomes difficult to secure a necessary polishing force in an abrasive product.

[0007] Therefore, in the conventional abrasive, a fluorine component is added by performing fluoridation during the production of the abrasive, and the required smoothness of the surface to be polished and the polishing force at the time of polishing are reduced by the effect of the added fluorine component. Is secured. As described above, the fluorine component has the effect of improving the smoothness of the surface to be polished and the effect of increasing the polishing force. For example, Japanese Patent Laid-Open No. 9-1
No. 83966 discloses a method of producing an abrasive by dropping an aqueous fluorine solution into a raw slurry after wet pulverization while stirring so that the fluorine content in the abrasive product is 3% by weight to 9% by weight. Is disclosed.

However, if the required smoothness and polishing power are secured by adding fluorine, the concentration of the fluorine component in the abrasive becomes high, so that the fine abrasives tend to adhere to the surface to be polished during polishing. In addition, there is a problem in that the surface to be polished tends to remain on the surface to be polished, so that the cleanability of the surface to be polished is reduced.

The present invention has been made in view of the above background, and has been made of a cerium-based material having a lower concentration of coarse particles, a higher polishing power, and an excellent cleanability of a surface to be polished. An object of the present invention is to provide a method for producing an abrasive.

[0010]

Means for Solving the Problems In order to solve such a problem, the present inventors have paid attention to a step of first pulverizing a raw material using a pulverizing device such as an attritor, and have found that the coarse particle concentration is lower. The grinding conditions under which the concentration of the finer abrasive particles was reduced and the grinding conditions under which the concentration of finer abrasive particles became lower were examined. However, for both coarse and fine abrasive particles,
No pulverizing conditions have been found that can keep the content lower.

Therefore, the present inventors have studied a wide range of pulverizing means without being bound by the conventional pulverizing method. As a result, they have found that, when a specific raw material is used, the raw material can be pulverized by a solution containing a fluorine component without using a pulverizing device such as an attritor to pulverize the raw material.

That is, the present invention provides a cerium-based abrasive having a step of pulverizing a raw material of a cerium-based abrasive, a step of roasting the pulverized raw material, and a step of pulverizing a roasted product obtained by roasting. In the method for producing an abrasive, as a raw material of a cerium-based abrasive, a cerium-based rare earth carbonate, or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide is used. And mixing the raw material and the fluorine component-containing solution to form a slurry to pulverize the raw material in the slurry.

In the step of pulverizing the raw material, a cerium-based rare earth carbonate or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide is used as a raw material, and the raw material is made into a slurry to form a slurry. Grind the raw material in the slurry. The size of the raw material before slurrying is not strictly limited, but usually the average particle size is 1000 μm or less, and this size is preferable. Further, the concentration of the solid component in the slurry is not particularly limited, but is used in ordinary pulverization and the like,
Preference is given to slurries having a solids content of 1% to 50% by weight.

In the present invention, when preparing the slurry, the raw material is made into a slurry state using a solution containing a fluorine component as the solution. In such a state, the raw material in the slurry (solid in the slurry) can be utilized by utilizing the fluorine component in the solution without using a conventional pulverizing apparatus for physically pulverizing the raw material such as an attritor, a ball mill, and a bead mill. Component) can be chemically ground. Then, when the raw material is pulverized in this way, the entire raw material can be pulverized more uniformly, and can be pulverized to a state in which both the coarse particle concentration and the fine particle concentration are low.

If the concentration of coarse particles in the raw material after pulverization can be reduced, the concentration of coarse particles in the abrasive product can be reduced more reliably. When the concentration of coarse particles in the abrasive is low, the generation of scratches on the surface to be polished due to the coarse particles is more reliably prevented, and the smoothness of the surface to be polished is improved. In addition, if the whole raw material can be ground evenly, and if the fine particles can be ground so that the concentration of fine particles in the raw material after grinding is low, the particle size of each abrasive particle constituting the abrasive is uniform with the average particle size. Therefore, the polishing speed is improved.

If the required smoothness and polishing rate are secured,
Further, since it is not necessary to add a fluorine component to secure these performances, the fluorine component concentration in the abrasive product can be reduced. And, by reducing the fluorine component concentration, it becomes possible to improve the cleanability of the polished surface. Further, in recent years, a high level of environmental measures has been required year by year, and it is considered that a lower concentration of the fluorine component is expected to be required. Since the fluorine component concentration can be further reduced, such a demand can be more reliably met.

It is considered that such a good result is obtained because the chemical pulverization method here can uniformly pulverize the entire raw material, unlike the conventional physical pulverization method.

Conventional physical pulverization by a pulverizing device such as an attritor is a method in which a raw material is pulverized by forcibly moving a pulverizing medium such as a ball and causing the pulverizing media to collide with each other. And unprocessed raw materials. From such a fact, it is considered that a raw material that is insufficiently pulverized is generated and coarse particles remain, while excessive pulverization is performed to generate fine particles. On the other hand, the chemical pulverization here is a method of pulverizing the raw material (solid component in the slurry) by the fluorine component in the liquid which is uniformly present in the entire slurry. it can. Therefore, it is considered that generation of fine particles can be prevented while remaining coarse particles, and the entire raw material (solid component in the slurry) can be uniformly pulverized.

The solution used for preparing the slurry includes, for example, an aqueous solution of hydrogen fluoride containing a water-soluble fluoride, ammonium fluoride and the like. In the pulverization, the chemical pulverization using the fluorine component in the slurry solution and the conventional physical pulverization can be used together, and by using them together, more efficient pulverization can be performed. It is. When used in combination, it is preferable to perform the chemical pulverization before or simultaneously with the conventional physical pulverization. When chemical grinding is performed after physical grinding,
This is because the physically pulverized raw material is further chemically pulverized, and the purpose of reducing the concentration of fine particles in the raw material cannot be achieved.

Incidentally, in the case of performing chemical pulverization, in order to perform pulverization as quickly as possible, the higher the fluorine component concentration in the slurry solution, the better. However, if the fluorine component concentration is too high, it is difficult to lower the fluorine component concentration in the finally manufactured abrasive product. Since the fluorine component in the raw material escapes from the raw material by roasting after pulverization, the concentration of the fluorine component in the raw material can be reduced by this.However, as described later, fluorine This is because it is not always possible to perform roasting necessary and sufficient for adjusting the component concentration. On the other hand, if the fluorine component concentration in the slurry solution is too low, chemical pulverization becomes difficult to proceed.

Therefore, the concentration of the fluorine component in the slurry solution in the step of pulverizing using the fluorine-containing solution was examined. As a result, it was found that chemical pulverization was possible with a solution having a low fluorine component concentration. Specifically, the maximum value of the fluorine component concentration in the slurry solution is:
It has been found that 0.001 mol / L to 1.0 mol / L is preferable.

The reason why the upper limit of the maximum value of the fluorine component concentration in the solution is limited to 1.0 mol / L is that if the maximum value is exceeded, it becomes difficult to keep the fluorine component concentration of the abrasive product low. The effect of chemically pulverizing the raw material is considered to be obtained when the fluorine solution is contained in the slurry solution. However, from the viewpoint of securing the productivity (pulverization efficiency) in the pulverization step, the effect of fluorine is considered. Component concentration is 0.001
mol / L or more is preferable.

In the pulverization step using a fluorine solution, as the pulverization of the raw material proceeds, the rare earth element in the solid component and the fluorine component in the solution react to form insoluble rare earth fluoride. The fluorine component concentration gradually decreases. In this case, the pulverization proceeds as long as the fluorine component is present in the slurry solution without newly adding a fluorine component during the pulverization, but the fluorine component may be added as needed. By increasing the concentration of the fluorine component in the slurry solution or keeping it constant, more uniform pulverization can be realized and the pulverization time can be shortened.

However, if the fluorine component-containing solution is added too much, it is difficult to lower the fluorine component concentration in the abrasive product even if the maximum value of the fluorine component concentration in the solution does not deviate from the above range. Become. If the fluorine concentration in the abrasive cannot be reduced, the cleaning properties will decrease.
As a result of study on this point, it is preferable that the fluorine component concentration of the raw material obtained after the step of pulverizing the raw material in the slurry using the fluorine-containing solution is 0.01% by weight to 4.0% by weight. It was found that abrasives could be easily manufactured. If the fluorine component concentration of the raw material after the grinding is within this range, regardless of whether the fluorine component is added during the grinding, the fluorine component concentration in the abrasive product is surely limited, and the cleaning property is excellent. Abrasives can be manufactured more reliably. Here, the fluorine component concentration of the raw material is the weight ratio of the fluorine element content to TREO (total rare earth oxide content) in the raw material or abrasive product. Thus TRE
The use of O as the basis is that the raw material containing the rare earth carbonate and the abrasive material have the property that the weight is reduced by roasting, and the fluorine component concentration is defined based on the weight of the raw material. This is because it is not always possible to accurately compare the fluorine component concentration before and after roasting.

As described above, in the present invention, a cerium-based rare earth carbonate or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide is used as a raw material. According to the chemical pulverization, the raw material can be pulverized to a state where the concentration of coarse particles and the concentration of fine particles are extremely low by the fluorine component in the slurry. This is considered to be an effect mainly caused by the relation with rare earth carbonate. Because.

[0026] "Cerium-based rare earth" refers to TRE
The ratio of cerium oxide (CeO ₂ ) to O is 30% by weight or more, and in the case of ordinary abrasive production, a value in the range of 40% by weight to 99% by weight is used. . The “cerium-based rare earth carbonate” is obtained from a “cerium-based rare earth” aqueous solution by a precipitant containing a carbonate group. For example, rare earth chloride can be exemplified as a cerium-based rare earth aqueous solution, and ammonium carbonate can be exemplified as a precipitant. The “cerium-based rare earth oxide” is obtained by roasting and oxidizing a cerium-based rare earth carbonate.

Therefore, the preferred range of the raw material used in the method for producing a cerium-based abrasive according to the present invention is defined as the loss on ignition of the raw material for the cerium-based abrasive (hereinafter, LOI (Loss).
On Ignition). ). LOI is a weight reduction rate when an object is ignited. Its value is about 30% to 40% by weight for rare earth carbonate and 0% for fully oxidized rare earth. In other words, if the LOI is known, the ratio of the rare earth carbonate in the raw material, which is considered to be closely related to the chemical pulverization, is known.

As a result of examining a raw material containing a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide,
It has been found that a raw material for a cerium-based abrasive having a loss on ignition of 1.0 to 40% by weight when heated at 1000 ° C. for 1 hour is preferable. When the ratio of the rare earth carbonate is reduced to a level where the LOI is smaller than 1.0% by weight, it is considered that the effect of chemically pulverizing the raw material with the water-soluble fluoride during pulverization is hardly obtained. Note that those having an LOI of less than 0.5% by weight are usually referred to as rare earth oxides.

The LOI of the raw material is measured according to JIS-K-00
67 (1992, Japan Standards Association).
Briefly, first, a small amount of raw material collected from the raw material was heated (preliminary drying) at 105 ° C. for 1 hour, sufficiently dried, and then placed in a crucible, and its weight was measured to the order of 0.1 mg. Thereafter, these were heated in an electric furnace at 1000 ° C. for 1 hour and allowed to cool in a dry atmosphere, then the weight of the crucible containing the raw materials was measured again, and the ignition loss was determined based on the weight difference between the two weight measurements. Was. In the present invention, the ignition loss is 10
After measuring at 00 ° C for 1 hour,
In the case of a rare earth salt, it has been experimentally confirmed that the value of the ignition loss starts to be stabilized by heating at 500 ° C. or more,
Is based on the belief that heating at is applicable as the most stable index.

By the way, a raw material in which a cerium-based rare earth carbonate and a cerium-based rare earth oxide are mixed is roughly classified into a raw material obtained by roasting a cerium-based rare earth carbonate, and a cerium-based rare earth carbonate and a cerium-based rare earth carbonate. There are raw materials obtained by mixing with rare earth oxides, but the former raw materials are more excellent in grindability, and the use of the former raw materials lowers the coarse particle concentration of the abrasive product because it is lower Is more preferable. That is, it is considered that since the latter raw material contains a rare earth oxide that is hard and hard to be pulverized, the pulverization hardly proceeds, and the concentration of coarse particles tends to increase.
On the other hand, in the former raw material, the entire raw material is appropriately roasted and the LOI is adjusted, and the firing of the rare earth oxide obtained by completely roasting the rare earth carbonate is prevented. It is considered that the coarse particle concentration is more easily reduced.

When the step of pulverizing the raw material is completed, an abrasive is manufactured by performing the same steps as in the ordinary manufacturing steps as described in the background art. Specifically, first, a chemical treatment (wet treatment) is performed, if necessary, followed by filtration and drying. Thereafter, it is roasted and crushed (reground). In the case of crushing by wet pulverization and producing an abrasive in a slurry state, the abrasive is produced when the crushing is completed.
In other cases, the crushed raw material is usually classified to obtain an abrasive having a desired particle size and particle size distribution.

The concentration of the fluorine component in the raw material is adjusted not only by adjusting the concentration of fluorine in the solution used for preparing the slurry in the step of pulverizing the raw material, but also by roasting after the step of pulverizing the abrasive. Done. It is because the fluorine component in the raw material can be removed by roasting. However, since the roasting step is to roast the raw material so that the abrasive raw material particles grow to an appropriate size in relation to the particle size of the abrasive to be finally manufactured, It is not always possible to always select the roasting conditions (temperature and time) such that the fluorine component concentration in the raw material becomes an appropriate value. Therefore, in order to surely lower the fluorine component concentration in the abrasive,
In the step of pulverizing the raw material, it is necessary to reduce the fluorine concentration in the raw material as much as possible. In this regard, according to the present invention,
Since the fluorine component concentration in the process of pulverizing the raw material can be reduced and the fluorination treatment is not required, the fluorine component concentration in the raw material before roasting can be kept low, and the raw material and abrasive after roasting can be reduced. The concentration of the fluorine component in the product can be easily and reliably kept within the above range.

According to the method for producing an abrasive described above, an abrasive having a low concentration of coarse particles and a low concentration of fine particles can be easily produced. However, as a result of investigation, the production of a cerium-based abrasive according to the present invention has been studied. Among the abrasives produced by the method, those having a fluorine element content of 0.01% by weight to 3.0% by weight based on TREO in the abrasive have excellent smoothness and cleanability of the polished surface. In addition, it was found that the abrasive was less abrasive during polishing and had high abrasive power. The fluorine component concentration in the abrasive product is a weight ratio of the fluorine element content to TREO in the abrasive product. If the fluorine component concentration is 0.01% by weight or less, the surface to be polished is inferior in smoothness, while if it exceeds 3.0% by weight, the cleaning property is inferior. In addition, for polishing glass substrates for electronic materials that require high flatness,
In particular, an abrasive having excellent cleaning properties is required. For such an application, the fluorine component concentration in the abrasive is particularly low at 0.01%.
% By weight to 1.0% by weight are preferred.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

First Embodiment : As a cerium-based abrasive raw material, TREO is 69.5% by weight, cerium oxide (CeO ₂ ) in TREO is 60% by weight, and TREO is
Used was a rare earth carbonate having a fluorine content of 0.02% by weight. The average particle size of the raw material is about 500 μm
Met. The LOI of the raw material was 30% by weight.
The method of measuring the LOI is as described above, and the description is omitted.

2 kg of the raw material was mixed with 2 L of an aqueous solution having a hydrogen fluoride (HF) concentration of 0.01 mol / L to prepare a slurry having a solid content of 50% by weight.

This slurry was stirred at room temperature (20 ° C.) for 1 hour, and thereafter, an attritor (MA-1S, manufactured by Mitsui Miike Seisakusho Co., Ltd.) into which 10 kg of a ball having a diameter of 4 mm was introduced.
Using E), wet grinding was performed for 3 hours. After the pulverization, the solid component was filtered to obtain a cake. The cake was dried, roasted (850 ° C.), crushed, and then crushed.
Classification to remove particles of m or more, the average particle size is 1.0μ
m of a cerium-based abrasive product was obtained. In each of the embodiments and the comparative examples, a cerium-based abrasive having an average particle diameter of 1.0 μm is manufactured. Roasting is performed so that the grains grow to the diameter, and crushing is performed so that necessary crushing is performed.

In the following embodiments and comparative examples, including the first embodiment, the fluorine component concentration was measured for the solid component of the slurry at the end of stirring and the finally obtained abrasive. Further, the coarse particle concentration (the concentration of particles having a particle diameter of 10 μm or more) was measured for the raw materials at the end of stirring and at the end of wet pulverization and the finally obtained abrasive product.

Measurement of fluorine component concentration: The fluorine component concentration was measured in accordance with the method for measuring fluorine compounds (ion electrode method) described in "JIS-K-010234". Measurement is also used), and the description is omitted. Table 1 shows the results.

Measurement of Coarse Particle Concentration: The measurement of coarse particle concentration was performed as follows. For the measurement object, an amount corresponding to the solid component weight of 200 g was weighed and collected, and this was dispersed in an aqueous solution containing 0.1% by weight of sodium hexametaphosphate as a dispersant and stirred for 2 minutes to produce a slurry. This slurry was filtered through a micro sieve having a pore size of 10 μm, and the residue on the sieve was recovered. The collected residue was again dispersed in a 0.1% by weight sodium hexametaphosphate solution to form a slurry. At this time, the dispersion was carried out by ultrasonic stirring for 1
Go for a minute. Then, the slurry was filtered with a micro sieve having a pore size of 10 μm. Re-slurry and filtration of the collected residue were performed twice to collect coarse particles. Thereafter, the coarse particles were sufficiently dried and weighed, and the coarse particle concentration was determined from the weight of the coarse particles.

Second to fifth embodiments and comparative examples 1 to 5
3 : Using the same raw material as used in the first embodiment, a step of pulverizing the raw material by changing the concentration of hydrogen fluoride in the aqueous solution used for preparing the slurry was performed. Table 1 shows the fluorine concentration in each embodiment. Other abrasive production conditions are:
It was the same as the first embodiment.

[0042]

[Table 1]

In Comparative Example 3, a slurry was prepared using an aqueous solution (pure water) containing no fluorine component, but the raw material obtained after stirring had an extremely high coarse particle concentration.
On the other hand, according to the first embodiment, a raw material having a low concentration of coarse particles was obtained after stirring. That is, it was found that by preparing a slurry using an aqueous solution having a fluorine component concentration of 0.001 mol / L or more, chemical pulverization using the fluorine component contained in the solution can be performed.
Further, the concentration of coarse particles in the finally obtained abrasive product was also suppressed as compared with Comparative Example 3, and it was also found that the abrasive had an effect of reducing the concentration of coarse particles in the abrasive. Note that 0.
Even at a concentration of 001 mol / L or less, a pulverizing effect can be obtained if a fluorine component is contained in the solution, but it has been found that it takes time to perform necessary pulverization. Further, the stirring operation is considered to promote chemical pulverization using a fluorine component in the slurry, and is therefore preferable for improving the pulverization efficiency.

As shown in the results of the second to fifth embodiments, as the concentration of fluorine in the solution used for preparing the slurry was increased, the concentration of the coarse particles of the raw material obtained after stirring or after the pulverizing step was reduced. It turns out that it can be reduced. On the other hand, as can be seen from Comparative Example 1, it was found that when the fluorine component concentration in the aqueous solution used for preparing the slurry became 5.0 mol / L, the concentration of coarse particles in the abrasive product increased rather. When the fluorine concentration in the solution is increased, chemical pulverization is accelerated, and the concentration of coarse particles in the raw material obtained after the pulverization is reduced, but the fluorine concentration in the raw material is increased. As a result, it is considered that the grain growth during roasting is excessively promoted, and the concentration of coarse particles in the abrasive product is rather increased.

Sixth to Ninth Embodiments and Comparative Example 4 : The raw materials used in the first embodiment were calcined at 600 to 800 ° C. for a predetermined time to adjust the LOI to a predetermined value. The LOI of the raw materials of each embodiment is as shown in Table 2. The other abrasive material manufacturing conditions were the same as in the fourth embodiment, and a description thereof will be omitted.

Tenth and eleventh embodiments : An aqueous solution of ammonium fluoride (NH ₄ F) was used as a fluorine-containing aqueous solution used when preparing a slurry. Other abrasive production conditions were the same in the tenth embodiment as in the fourth embodiment, and in the eleventh embodiment as in the eighth embodiment.

[0047]

[Table 2]

As can be seen from the results of the embodiments, when the LOI of the raw material is 1.0% by weight or more, the concentration of coarse particles in the raw material and the abrasive product obtained after stirring (chemical pulverization) becomes low. The result was obtained. On the other hand, as shown in Comparative Example 4, when the raw material having an LOI of 0.5% by weight was used, the concentration of coarse particles could not be reduced by the stirring treatment (chemical pulverization). Therefore, the raw material of the cerium-based abrasive is preferably a cerium-based rare earth carbonate or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide. More specifically, the LOI is 1.0% by weight. It has been found that the above is preferable. It is considered that such a result is due to the effect of the fluorine component in the slurry that pulverizes the coarse particles mainly due to the effect on rare earth carbonate. Also, LO
It has been found that the upper limit of I is not particularly limited, and it is preferable that the upper limit of LOI of the rare earth carbonate raw material available as the raw material is 40% by weight or less. However, in order to accurately adjust the fluorine component concentration in the slurry, it is preferable that the raw materials have physical properties as stable as possible. In consideration of this point, the LOI of the raw material is more preferably 30% by weight or less.

Polishing test : A polishing test was performed on the cerium-based abrasive in a slurry state obtained in each of the embodiments and the comparative examples, and the polishing value was measured and the state of the polished surface was evaluated (evaluation of scratches). In the polishing test, a high-speed polishing tester was used as a test device, a glass for a flat panel of 65 mmφ was used as a material to be polished, and the glass was polished using a polishing pad made of polyurethane. In the polishing test, the obtained abrasive was further dispersed in water to prepare an abrasive slurry having a slurry concentration of 10% by weight. The polishing conditions were such that the prepared abrasive slurry was supplied at a rate of 5 ml / min, the pressure on the polished surface was set at 15.7 kg / cm ^2, and the rotation speed of the polishing tester was set at 1000 rpm. .
The polished glass material was washed with pure water and dried in a dust-free state.

Evaluation of polishing value : In the above polishing test,
The polishing value was determined based on the amount of reduction in the glass weight determined by measuring the glass weight before and after polishing. Therefore, the higher the polishing value, the higher the polishing power. Here, the polishing value when polishing was performed using the polishing material of the first embodiment was set as a reference (100).

Evaluation of flaw : Evaluation of the condition of the polished surface. Flaws were evaluated based on the presence or absence of scratches on the polished surface and the presence or absence of abrasive particles on the polished surface. Specifically, the surface of the polished glass is irradiated with a halogen lamp of 300,000 lux, the surface of the glass is observed by a reflection method, and the degree (size) of the flaw is determined to obtain a score. The evaluation points were determined by the deduction method. Table 3 shows the results of the test.

Evaluation of Detergency : The detergency test of the abrasive was carried out on the assumption that the polished surface was polished using the cerium-based abrasive obtained in each embodiment and comparative example. In the test, a glass preparation for optical microscope observation, which was washed and dried by ultrasonic cleaning, was prepared. And disperse the cerium-based abrasive in water,
An abrasive slurry having a concentration of 10% by weight was obtained. The prepared slide was immersed in the abrasive slurry, and then pulled up and dried sufficiently with a drier to attach the abrasive to the surface of the prepared slide to obtain a test piece for a cleaning test. The temperature of the preparation atmosphere during drying was 50 ° C. Then, ultrasonic cleaning was performed for 5 minutes while the obtained test piece was immersed in pure water in a beaker. After washing, the preparation was taken out of the beaker and washed with running pure water. Then, the surface of the prepared slide after washing with running water was observed with an optical microscope, and the remaining amount of abrasive particles remaining on the surface was evaluated. Table 3 shows the evaluation results.

[0053]

[Table 3]

As can be seen from the table, with the abrasive of each embodiment, good results were obtained for all of the abrasive values, scratches and detergency. On the other hand, the abrasive of Comparative Example 1 was excellent in abrasive power, but poor in flaw evaluation and cleanability. This is because the fluorine component concentration at the end of the pulverization was increased, and the grain growth became easy to progress, so that the coarse particle concentration was increased, and sufficient roasting was performed to suppress the generation of the coarse particles. This is considered to be due to the fact that the concentration of fluorine could not be reduced by roasting. The abrasive of Comparative Example 2 also showed the same tendency as that of Comparative Example 1, but the detergency was slightly improved, which is considered to be due to the low fluorine component concentration.
The level of detergency did not reach a sufficiently improved level. The abrasive of Comparative Example 3, to which no fluorine was added, was poorly evaluated in all of the abrasive values, scratches, and detergency, and it was found that a fluorine component was necessary to ensure the required performance for these. The abrasive of Comparative Example 4 had a low scratch evaluation. In Comparative Example 4, since the rare earth oxide was used as a raw material, pulverization of the raw material did not proceed, and the residual amount of coarse particles increased.
This is considered to have been evaluated.

As a result, a slurry was prepared by mixing the raw material and a solution having a fluorine component concentration in the above-described range.
With this, if the raw material is chemically ground, the abrasive value, scratches,
It has been found that a cerium-based abrasive having good characteristics in all aspects such as detergency can be easily produced.

The fluorine concentration in the abrasive product is
It has been found that 0.01% to 3.0% by weight is preferable. Further, if the fluorine component concentration in the raw material after the completion of the stirring treatment is adjusted to 0.01% by weight to 4.0% by weight, the fluorine concentration in the abrasive product can be reduced to 3.0% by weight or less, which is preferable. (Table 1). Further, from the results of this test, higher flatness is required, and polishing of a glass substrate for an electronic material, which requires an abrasive having more excellent detergency, is required to have a fluorine component concentration of 1.0% by weight or less. It turned out to be more suitable. If the concentration of the fluorine component in the raw material after the completion of the stirring treatment is set to 3.0% by weight or less,
It was found that the fluorine concentration in the abrasive product could be reduced to 1.0% by weight or less, which was preferable (see Table 1).

[0057]

As can be understood from the above description, according to the present invention, a cerium-based material having a lower concentration of coarse particles, a higher polishing power, and excellent cleanability of the surface to be polished. Abrasives can be manufactured.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshitsugu Uchino 1-11-11 Osaki, Shinagawa-ku, Tokyo Mitsui Kinzoku Mining Co., Ltd. Functional Materials Business Unit Rare Metal Division (72) Inventor Kazuya Ushiyama Shinagawa-ku, Tokyo 1-11-1, Osaki F-term (Reference) 4M076 AA02 AB02 AB09 BA24 BA46 BD02 CA36 DA30

Claims (5)

[Claims] 1. Production of a cerium-based abrasive having a step of pulverizing a raw material of a cerium-based abrasive, a step of roasting the pulverized raw material, and a step of pulverizing a roasted product obtained by the roasting In the method, as the raw material of the cerium-based abrasive, a cerium-based rare earth carbonate or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide is used. A method for producing a cerium-based abrasive, comprising a step of pulverizing raw materials in a slurry by mixing a component-containing solution to form a slurry. 2. The method for producing a cerium-based abrasive according to claim 1, wherein the maximum value of the fluorine component concentration in the slurry solution is 0.001 mol / L to 1.0 mol / L. 3. The fluorine component concentration of the raw material obtained after the step of pulverizing the raw material in the slurry using the fluorine-containing solution is 0.01% by weight to 4.0% by weight.
Alternatively, the method for producing a cerium-based abrasive according to claim 2. 4. The raw material of the cerium-based abrasive is 1000 ° C.
Loss when heated for 1 hour at 1.0 to 40% by weight
The method for producing a cerium-based abrasive according to any one of claims 1 to 3, wherein the amount is% by weight. 5. A cerium-based abrasive produced by the method for producing a cerium-based abrasive according to any one of claims 1 to 4, wherein the fluorine component concentration is 0.01%.
A cerium-based abrasive having a weight percentage of 3.0 to 3.0% by weight.