JP2002129144A - Cerium oxide abrasive for glass and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cerium oxide abrasive used as a glass abrasive reduced in cost by using clay as part of its starting materials and possessing excellent abrasive performances as compared with those of a clay-free one. SOLUTION: A cerium oxide abrasive for glass produced by treating a mixture of clay and starting materials for a cerium oxide abrasive with fluorine. This abrasive comprises 0.1-20 wt.% clay, 0.5-10 wt.% fluorine, and the balance of rare earth oxides mainly consisting of cerium oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a cerium oxide abrasive for glass and a method for producing the same.

[0002]

2. Description of the Related Art With the recent spread of the use of glass substrates for computer hard disks and the spread of TFT color liquid crystals,
To supply even cheaper and higher quality products to the market,
There has been a demand for lower glass substrate prices. In order to supply the glass substrate to the market at lower cost, it seems that the most effective method is to respond by improving the production process of the glass itself, changing the material, etc., but it is used in the above-mentioned fields. The glass substrate is different from ordinary glass, and the technology for polishing the glass surface determines the product quality.

[0003] For these types of glass polishing, cerium oxide-based abrasives have been known as the most excellent ones, and the higher the cerium oxide grade in the abrasives, the higher the quality of the glass abrasives. .

That is, a conventional cerium oxide-based abrasive for glass is a mixed material obtained by mixing a cerium oxide-based abrasive material and water, and the mixed material is mixed and pulverized using a mixing and pulverizer to form a pulverized slurry. The pulverized slurry and the hydrofluoric acid solution are mixed to obtain a fluorine-containing pulverized slurry, and the fluorine-containing pulverized slurry is filtered to collect a cake, and the filtered cake is dried to about 750 to 1000 ° C. It has been manufactured by roasting at a temperature to obtain a powder, pulverizing and sizing the powder, and classifying the powder. Accordingly, the grade of the abrasive is determined by the cerium oxide grade in the cerium oxide-based abrasive raw material, and there has been no abrasive raw material that can replace cerium oxide.

[0005]

However, as the quality of cerium oxide in the cerium oxide-based abrasive material is improved, the price of the material is inevitably increased, and the manufacturing process is simplified and improved in efficiency. Even so, we can judge that we will not be able to supply cheaper and higher quality products than before.

[0006] For this reason, various studies have been made and reports have been made in consideration of replacing a part of the cerium oxide-based abrasive with another component and using it for glass polishing. For example,
Japanese Patent Application Laid-Open No. 60-44577 discloses an abrasive in which a rare earth is combined with an oxidized derivative of a silicate, and Japanese Patent Application Laid-Open No. 10-183103 discloses a rare earth carbonate and a silicon oxide derivative. A combined abrasive is disclosed.

[0007] However, when the present researchers conducted confirmation experiments, it was found that the abrasives according to the inventions disclosed therein could not obtain a sufficient polishing force, and even if a sufficient polishing force could be confirmed, The impression that it was difficult to bring out stable polishing performance without defects was obtained. Therefore, it was determined that the polishing was not suitable for precision polishing that could be used for finish polishing of a glass substrate used for hardware or the like.

[0008]

The inventors of the present invention have made intensive studies and considered replacing some of the cerium oxide-based abrasive materials with other materials. As a result, they conceived of using clay which can be used as a bulking agent and which is inexpensive. In addition, even if clay is used, a cerium oxide-based abrasive which can be applied to polishing of a glass substrate used for hardware or the like has been developed.

A cerium oxide-based abrasive for glass obtained by subjecting a mixture of a cerium oxide-based abrasive raw material and clay to fluorination treatment, wherein the clay is 0.1 to 20 wt.
%, The content of fluorine is 0.5 to 10 wt%, and the balance is a rare earth oxide mainly containing cerium oxide. This claim 1
As can be seen from the above, the cerium oxide abrasive for glass, which is the final product, is eager to adopt a configuration in which the clay is 0.1 to 20 wt%, the fluorine content is 0.5 to 10 wt%, and the balance is rare earth oxide. Research has shown that it is optimal.

Here, the reason why the content of clay is set to 0.1 to 20% by weight is that the abrasive is used in order to obtain a clean smooth surface by the particles contained therein abrading the surface to be polished. By changing the composition of the components, they can be used in applications ranging from finish polishing to rough polishing. Therefore, the lower limit of 0.1 w
Even if the amount of the clay is less than t%, no problem occurs as an abrasive for glass, but the effect of lowering the price, which is originally intended, is not obtained at all.
On the other hand, if the amount of clay is increased beyond the upper limit of 20 wt%, the price becomes very low, but
The polished glass surface is apt to be scratched, resulting in poor finishing accuracy.

Next, the content of fluorine will be described. Fluorine forms a compound with the rare earth element contained during roasting, enables roasting at a low temperature, and acts to play a role in promoting the growth of crystal grains during roasting. Further, fluorine has been considered to play a role of slightly dissolving the glass surface by a chemical action when performing glass polishing, and to act so that glass polishing can be performed more smoothly. Therefore, it can be said that glass polishing with a polishing material for cerium oxide-based glass is equivalent to a kind of tribological polishing. Therefore, the amount of fluorine contained in the cerium oxide-based abrasive for glass should also be determined in consideration of the balance with other constituent components, and in relation to the above-mentioned clay content, the fluorine content is 0.1%. Preferably, it is in the range of 5 to 10 wt%. Therefore, if the fluorine content in this region deviates, the finishing accuracy of the polished glass surface will be poor. Among them, the most beautiful finished surface is obtained when the fluorine content is 1 to 8 wt.
% Range is more preferable.

The clay used here has a sintering aid.
It is desirable to use clay that can play a role.
For this purpose, alumina is the main component of clay.
(Al ₂O₃) And silica (SiO₂)
It is preferable to use them.

These components are generally widely used as an abrasive. In the cerium oxide-based abrasive for glass according to the present invention, the chemical polishing effect of the glass surface by fluorine and the alumina (Al ₂ O ₃ ) And silica (SiO ₂ )
Abrasive polishing of the glass surface caused by superposition occurs superimposedly, and the rare earth oxide containing cerium oxide as a main component contributes to fine and highly accurate polishing, so that the glass surface can be efficiently polished when viewed as a whole, It is possible to obtain an excellent polishing ability, and it is possible to obtain a polishing power higher than that of a conventional cerium oxide-based abrasive.

Therefore, a second aspect of the present invention is the cerium oxide-based abrasive for glass according to the first aspect, wherein the clay has a total content of alumina and silica of 75.0 wt% or more. As described above, alumina (Al ₂
Clays composed of O ₃ ) and silica (SiO ₂ ) have been considered desirable, because various trace components are contained in the clays.

Other minor components include, for example, iron oxide, sodium oxide, magnesium oxide, potassium oxide, calcium oxide, manganese dioxide and the like. If these substances are included in the final product, abrasives, even if the glass is polished and then cleaned, trace impurities will remain on the glass surface and adversely affect the performance of the glass.
Care must be taken to minimize contamination of these final products. Therefore, the total content of alumina and silica, which are components that originally contribute to glass polishing, is not less than a certain value, and the total content of alumina and silica is 75.0 wt. The percentage is specified here.

[0016] Then, as a clay meeting this condition,
As described in claim 3, it is preferable to use at least one of bentonite, ball clay, and kaolin as the clay that can serve as a sintering aid. Bentonite is 14wt% alumina, 63wt% silica
%, About 28 wt% alumina in ball clay,
Silica is contained at about 55 wt%, kaolin contains about 38 wt% of alumina, and silica is contained at about 44 wt%, and the other trace components are the same as those described above.

The rare earth oxide mainly containing cerium oxide has a cerium oxide grade of CeO ₂ / TREO = 5.
The cerium oxide-based abrasive for glass according to any one of claims 1 to 3, which is 0% or more. Certainly, in order to obtain the polishing effect of the glass surface by cerium oxide with emphasis, the higher the cerium oxide content, the more desirable. However, in terms of cost, it must be extremely expensive. Therefore, when the present inventors use it as a fluorine-containing cerium oxide-based abrasive for glass, at least CeO ₂ / TRE
If O = 50% can be secured, it is possible to obtain a polishing power equal to or higher than that of a conventional cerium oxide-based abrasive even when used in combination with clay.

Hereinafter, claims 1 to 4 of the present invention will be described.
The method for producing the cerium oxide-based abrasive for glass described in 1 above will be described. Claim 5 is the method for producing a cerium oxide-based abrasive for glass according to any one of claims 1 to 4, wherein a mixed material obtained by mixing a cerium oxide-based abrasive material, clay and water. The mixed raw material is mixed and pulverized using a mixing and pulverizer to obtain a pulverized slurry, and the pulverized slurry is subjected to a fluorination treatment by contacting the pulverized slurry with a hydrofluoric acid solution having a predetermined concentration to obtain a pulverized slurry. And filtering the cake, drying the filtered cake and roasting at a temperature of 700 to 1050 ° C. to form a powder, sizing and classifying the powder to produce a product. The method is characterized by a method for producing a cerium oxide-based abrasive for glass.

In this production method, particularly important are the pulverization time and the roasting temperature when a pulverized slurry is obtained using a mixing and pulverizer. The former pulverization time is set differently depending on whether the final fluorinated cerium oxide-based abrasive for glass is used for finish polishing, rough polishing, or intermediate polishing thereof. At this time, since the clay is more easily pulverized than the cerium oxide-based abrasive raw material, it is necessary to pay attention to the pulverization time, considering that a certain particle size adjusting effect is expected.

As a procedure of pulverizing with a mixing and pulverizing machine, a method of putting only a cerium oxide-based abrasive material and water into a mixing and pulverizing machine, stirring the mixture for a predetermined time, and then adding clay is employed. It is also possible to do. More specifically, a cerium oxide-based abrasive material and water are put into a mixing and crushing machine, and after stirring for 1 to 2 hours, clay is added, and mixing and stirring are further performed for 1 to 3 hours. is there.

In the present specification, the cerium oxide-based abrasive raw material is a powdery substance such as a rare earth oxide or a rare earth carbonate, which means that a rare earth element remains in an oxide state by roasting. are doing. As the clay, any one of the above-mentioned bentonite, ball clay and kaolin or a mixture of two or more thereof is used.

The mixing and pulverizing machine is not particularly limited as long as it can mix and pulverize a material stored in a high energy ball mill or the like. By performing the mixing and pulverizing treatment, a pulverized slurry is obtained.

At this stage, the pulverized slurry and the fluorine-containing substance are brought into contact with each other to perform a fluorine treatment to obtain a fluorine-containing pulverized slurry. The hydrofluoric acid solution used at this time is subjected to a contact reaction with the pulverized slurry for 0.1 to 3 hours to perform the treatment.

When the fluorine treatment is completed, the fluorine-containing pulverized slurry is filtered to collect the cake.
The filtration method at this time is not particularly limited, and the filtration can be performed in a so-called cake state using a general high-pressure filtration method. Subsequently, the cake obtained by filtration is dried, roasted, and milled to obtain powder as an abrasive. The procedure itself at this time is exactly the same as the conventional production method.

As a result of intensive studies conducted by the present inventors, it has been found that when an attempt is made to obtain an abrasive by adding only clay without using a fluorine treatment, the firing temperature is reduced by 50 to 1 as compared with the case of the fluorine treatment.
Unless fired in a high temperature range of 750 ° C. to 1100 ° C. increased by about 00 ° C., the material cannot be used as an abrasive. On the other hand, as described in claim 5, the use of the fluorine treatment makes it possible to perform roasting in a low-temperature region even when using clay as a sintering material.

The powder after roasting is pulverized again and sized, and then subjected to a classification process using a so-called air classifier to obtain a low-fluorine cerium oxide-based abrasive for glass as a final product.

According to a sixth aspect of the present invention, in the mixed raw material obtained by mixing the cerium oxide-based abrasive material, clay and water, the mixing ratio of the cerium oxide-based abrasive material and the clay is 0.1%.
The method for producing a low-fluorine cerium oxide-based abrasive for glass according to claim 5, wherein the amount is 1 to 20 wt%. This defines the mixing ratio of the clay when the total weight of the cerium oxide-based abrasive material and the clay is 100 wt%. That is, as the mixing ratio of the clay increases, fine and good polishing becomes more difficult. Therefore, 20 wt%
If the amount of the clay exceeds that, it becomes difficult to use it as an abrasive in glass applications. On the other hand, 0.1
If the amount of the clay is less than wt%, the clay does not function as a sintering aid during roasting.

According to a seventh aspect of the present invention, the mixed raw material obtained by mixing the cerium oxide-based abrasive material, clay and water has a total weight of 100 w of the cerium oxide-based abrasive material, clay and water.
The method for producing a low fluorinated cerium oxide-based abrasive for glass according to any one of claims 5 and 6, wherein water is adjusted so as to be 30 to 60 wt% in the case of t%.

As described above, the amount of water to be added to the mixed raw material obtained by mixing the cerium oxide-based abrasive raw material, clay and water is defined as follows. There is also the purpose of crushing finely,
When the amount of water added increases, simple mixing is easy,
It takes time to obtain the effect of fine grinding. On the other hand, if the amount of water added is too small, the stirring resistance increases, and a large load is applied to the mixing and stirring device, and it is difficult to achieve the purpose of uniform mixing. Therefore, the inventors of the present invention consider that, when the total weight of the cerium oxide-based abrasive material, clay, and water is 100 wt%, water is 30 to 60 wt% for the reasons described above.
Therefore, it was determined that it would be desirable to adjust the value to%.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a cerium oxide-based abrasive for glass according to the present invention will be described, and the polishing value of the obtained abrasive during glass polishing will be described in more detail. Will be described. In the method for analyzing fluorine in abrasives in this specification, a sample is melted with an alkaline flux, allowed to cool, extracted with warm water, and the volume is adjusted. An appropriate amount thereof was collected, and after adding a buffer solution, the pH was adjusted to about 3.5,
Make the volume constant to make the sample solution. Several standard solutions were prepared in the same manner as the sample except that the sample was not used and the fluorine standard solution was added after fractionation, with the fluorine concentration changed. The standard solution and the sample solution were measured with an ion meter equipped with a fluorine ion electrode, the fluorine concentration of the sample solution was determined from the calibration curve obtained by the standard solution measurement, and the concentration was converted to the fluorine content of the sample. .

First Embodiment: Here, the flow shown in FIG. 1 is used, and a cerium oxide-based abrasive for glass is manufactured by the manufacturing method according to claim 5, and polishing is performed when the glass is polished. Value shall be shown.

As a cerium oxide-based abrasive material, a rare earth oxide obtained by calcining a rare earth carbonate at 750 ° C. and having a cerium oxide grade of CeO ₂ / TREO = 60%.
4 kg was used. And 0.6k kaolin in the clay
g, that is, 20 wt% of the total weight of the cerium oxide-based abrasive material and clay. In addition, the present inventors,
2.85 kg of the same cerium oxide-based abrasive material and 0.15 kg of clay were simultaneously produced in an amount of 5 wt%.

Then, 3 liters of water was added to 2.4 kg (2.85 kg for 5 wt%) and 0.6 kg (0.15 kg for 5 wt%) of the cerium oxide-based abrasive material. As a mixed raw material, put this mixed raw material into a high energy ball mill (so-called attritor),
The mixture was pulverized for 4 hours to obtain a pulverized slurry. 69.2 ml of a 55% hydrofluoric acid solution per liter of the pulverized slurry was added to the pulverized slurry, and the mixture was subjected to a fluorine treatment for 1 hour with stirring, followed by filtration.

Subsequently, the pulverized slurry was filtered to collect a cake. The filtration here was performed using a filter press. Thereafter, the cake collected by filtration was dried at a temperature of 120 ° C. for 24 hours.

After drying, the cake is roasted,
Mill crushing and air classification were performed to obtain a low fluorinated cerium oxide abrasive for glass. The roasting condition at this time is 70
Four conditions of 0 ° C., 750 ° C., 850 ° C., and 950 ° C. for 12 hours were obtained, and four types of cerium oxide abrasives for glass were obtained.

Further, the present inventors manufactured a cerium oxide-based abrasive for glass by the same method and under the same conditions and using ball clay and bentonite instead of kaolin used here. Together with these, Table 1 shows the polishing values when the glass was polished. The glass used for this evaluation was
The polishing was performed at a polishing pressure of 15.7 kg / cm 2 and an abrasive slurry concentration of 10 wt% using a flat panel glass having a diameter of 60 mm and a high-speed polishing machine. Further, in the table, the abrasive produced by the same method and under the same conditions as above using 3.0 kg of the cerium oxide-based abrasive raw material without the clay component is indicated as "no clay component" for comparison. It is published in. In addition,
The polishing value is obtained by measuring the weight of glass before and after polishing and converting the polished thickness from the specific gravity and glass diameter of the glass.

[0037]

[Table 1]

As can be seen from Table 1, the use of clay shows a higher polishing value than the case where no clay component was added. Therefore, by using clay, it is possible to reduce the use amount of cerium oxide and reduce the product cost, and it is possible to provide a cerium oxide-based abrasive with a higher abrasive force than when clay is not mixed. It becomes.

Second Embodiment: Here, the flow shown in FIG. 1 is the same as that of the first embodiment, but the case where the fluorine concentration at the time of performing the fluorine treatment is changed will be described. Therefore, the manufacturing flow itself is exactly the same as in the first embodiment, and a description thereof will be omitted. The difference is that a 55% hydrofluoric acid solution was added to the ground slurry at a rate of 23.0 per liter of ground slurry.
Add fluorinated for 1 hour with stirring,
Thereafter, filtration was performed.

Also, the present inventors produced a low fluorinated cerium oxide abrasive for glass in the same manner and under the same conditions and using ball clay and bentonite instead of kaolin as in the first embodiment. Table 2 also shows the polishing values when the glass is polished. The glass and polishing conditions used for this evaluation are the same as in the first embodiment. Further, in the table, the abrasive produced by the same method and under the same conditions as above using 3.0 kg of the cerium oxide-based abrasive raw material without the clay component is indicated as "no clay component" for comparison. The same applies to the points listed above.

[0041]

[Table 2]

As can be seen from Table 2, as compared with the case where no clay component was added, both the calcined product on the low temperature side and the roasted product on the high temperature side showed a higher polishing value. It is recognized that the same polishing value is obtained when any of kaolin, ball clay and bentonite is used. That is, the same result as in the first embodiment is obtained.

[0043]

According to the cerium oxide abrasive for glass according to the present invention, by replacing a part of rare earth oxides used as an abrasive for glass with inexpensive clay, it can be marketed at a lower price as an abrasive. It is possible to supply. Further, the abrasive according to the present invention has an abrasive power exceeding that of the cerium oxide-based abrasive used for conventional glass polishing.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a production flow of a cerium oxide-based abrasive for glass.

Claims (7)

[Claims] 1. A cerium oxide-based abrasive for glass produced by subjecting a mixture of a cerium oxide-based abrasive raw material and clay to fluorination treatment, wherein the clay is 0.1 to 20% by weight and the fluorine content is 0.1%. 5-1
A cerium oxide-based abrasive for glass, characterized by being a rare earth oxide mainly containing cerium oxide at 0 wt%. 2. The cerium oxide abrasive for glass according to claim 1, wherein the clay has a total content of alumina and silica of 75.0 wt% or more. 3. The cerium oxide-based abrasive for glass according to claim 1, wherein the clay is at least one of bentonite, ball clay, and kaolin. 4. The cerium oxide abrasive for glass according to claim 1, wherein the rare earth oxide mainly containing cerium oxide has a cerium oxide grade of CeO ₂ / TREO = 50% or more. 5. The method for producing a cerium oxide-based abrasive for glass according to any one of claims 1 to 4, wherein the cerium oxide-based abrasive is mixed with clay and water. The mixed raw material is mixed and pulverized using a mixing and pulverizer to form a pulverized slurry, the pulverized slurry and a fluorine-containing substance are brought into contact with each other to produce a fluorine-containing pulverized slurry, and the cake is obtained by filtering the pulverized slurry. An oxide for glass characterized in that the cake obtained by filtration is dried, roasted at a temperature of 700 to 1050 ° C. to form a powder, and the powder is sized and classified to produce a powder. A method for producing cerium-based abrasives. 6. A mixed raw material obtained by mixing a cerium oxide-based abrasive material, clay and water, wherein the mixing ratio of the cerium oxide-based abrasive material and clay is 0.1 to 20% by weight of the clay. 6. The method for producing a cerium oxide-based abrasive for glass according to 5. 7. A mixed raw material obtained by mixing a cerium oxide-based abrasive material, clay and water, wherein water is 30 to 30% by weight when the total weight of the cerium oxide-based abrasive material, clay and water is 100 wt%. The method for producing a cerium oxide-based abrasive for glass according to claim 5 or 6, wherein the amount is adjusted to be 60 wt%.