TW201638047A - Production method of composite metal oxide polishing material, and composite metal oxide polishing material - Google Patents

Abstract

A cerium-free polishing material is provided which has an excellent polishing speed, and which can cut production costs and has improved production efficiency; also provided is a production method for conveniently obtaining said polishing material. This production method of the composite metal oxide polishing material involves a mixing step for mixing a strontium compound and a zirconium compound and a firing step for firing the mixture obtained in the mixing step, wherein said zirconium compound contains less than or equal to 2.0 parts by weight of a sulfur compound in terms of SO3 per 100 parts by weight of said zirconium compound in terms of ZrO2.

Description

Method for producing composite metal oxide abrasive material and composite metal oxide abrasive material

The present invention relates to a method of producing a composite metal oxide abrasive material and a composite metal oxide abrasive material.

Oxide-based abrasives have been used in the industry for the polishing of precision optical glass products requiring high transparency and precision, such as lenses or enamels. This abrasive is produced by calcining and pulverizing a mineral containing a large amount of a rare earth element (rare earth).

However, since the demand for rare earth elements has increased and the supply has become unstable, it has been desired to develop techniques and substitute materials for reducing the amount of ruthenium used. In the case of the above-mentioned material, the perovskite type oxide is preferably used as a polishing material, and the iron-based perovskite type abrasive material is disclosed in Patent Document 2, and Patent Document 3 Among them, a zirconium perovskite type abrasive material is disclosed.

Prior technical literature

Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2001-107028

Patent Document 2: Japanese Laid-Open Patent Publication No. 2012-122042

Patent Document 3: Japanese Laid-Open Patent Publication No. 2013-82050

However, when glass polishing is performed using the abrasive material disclosed in Patent Document 1, there is a problem that the polished glass has a smooth surface, but the polishing rate is low.

Further, the abrasive material described in Patent Document 2 is produced by a spray pyrolysis method, and has a problem that it is not suitable for mass production because of special equipment and a large amount of time for manufacturing, or is worried about bismuth oxide due to the use of rare metals such as nickel or cobalt. The same supply is unstable. The abrasive material described in Patent Document 3 is also produced by a spray pyrolysis method, and is not suitable for mass production.

In view of the above, the present inventors have found that a method of obtaining an abrasive material by mixing and calcining a cerium compound and a zirconium compound is a method of manufacturing a flawless abrasive material at a low cost, which is simple in manufacturing process and requires no special equipment to be introduced. Among the abrasive materials obtained by this method, zirconia was used as the raw material zirconium compound, and the polishing rate was remarkably excellent. However, since zirconium oxide is usually produced by calcining and pulverizing zirconium hydroxide, in order to omit the calcination and pulverization steps, it is possible to further reduce the manufacturing cost and improve the production efficiency.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an abrasive material and a method for producing the same, which have a good polishing rate in a flawless abrasive material, and can reduce manufacturing cost and improve Manufacturing efficiency.

In order to solve the above problems, the inventors of the present invention have focused on the polishing materials obtained by mixing and calcining a cerium compound and a zirconium compound, and the polishing rate of the abrasive material using a zirconium compound other than zirconia as a raw material is not good. The main reason for the first discovery was the content of sulfur compounds contained in the raw material zirconium compound. In general, zirconium compounds such as zirconium hydroxide and zirconium carbonate are often used in the synthesis of a sulfate ion-containing substance such as sulfuric acid, ammonium sulfate, sodium sulfate or potassium sulfate. In the conventional zirconium oxychloride synthesis and precipitation method, by adding a substance containing a sulfate ion, the basic zirconium sulfate (Zr(OH) _(4-2x) (SO) is _{firstly used. 4) x} .nH ₂ O (where 0 <x <2)) to generate and then neutralizing the basic zirconium sulfate, thereby obtaining zirconium hydroxide, zirconium carbonate or zirconium compounds and the like. The reason for this is that when a sulfur compound is added, the water content of the obtained filter cake is lowered, and handleability or filterability is improved. In the case where no sulfur compound is added, the obtained zirconium hydroxide is filtered for a very long period of time, and the productivity is remarkably low, so that it is not industrially suitable. Therefore, the zirconium compound obtained by the usual synthesis method contains a sulfur compound, but the inventors have found for the first time that the content of the sulfur compound affects the polishing rate of the abrasive material after mixing with the cerium compound and calcination. Although the reason has not been determined, for example, one of the reasons is presumed to be that the crystallinity of the obtained zirconium compound differs depending on the amount of the sulfur compound added in the production of the zirconium compound. Therefore, it has been found that if the content of the sulfur compound in the zirconium compound is set to a specific range and it is mixed with the cerium compound and calcined, the abrasive material having a high level of polishing speed can be easily obtained, and the above can be completely solved. The subject matter is thus completed.

That is, the present invention is a method for producing a composite metal oxide abrasive material comprising the steps of mixing a mixed cerium compound and a zirconium compound, and a calcining step of calcining the mixture obtained by the mixing step, and the zirconium compound The amount of the SO ₃ equivalent of the sulfur compound is 2.0 parts by weight or less based on 100 parts by weight of the ZrO ₂ equivalent amount of the zirconium compound.

The ruthenium compound in the above mixing step is preferably at least one selected from the group consisting of cesium carbonate and cesium hydroxide. Since barium carbonate and barium hydroxide are easily reacted with the zirconium compound to easily form barium zirconate (SrZrO ₃ ), productivity can be further improved.

The zirconium compound in the above mixing step is preferably at least one selected from the group consisting of zirconium carbonate and zirconium hydroxide. Since zirconium carbonate and zirconium hydroxide have high reactivity with the ruthenium compound, it is possible to provide an abrasive material having more excellent polishing properties. Moreover, if these are used, it is possible to further reduce the manufacturing cost and improve the manufacturing efficiency.

The calcination temperature in the above calcination step is preferably more than 800 ° C and not more than 1500 ° C. If the calcination temperature is within this range, an abrasive material having more excellent polishing characteristics can be provided.

Further, the present invention is also a composite metal oxide abrasive material in which the SO ₃ equivalent amount of the sulfur compound contained in the composite metal oxide abrasive material is relative to the ZrO ₂ of the zirconium compound contained in the composite metal oxide abrasive material. The converted amount is 100 parts by weight or less and 1.2 parts by weight or less.

According to the method for producing a composite metal oxide abrasive of the present invention, an abrasive material having a good polishing rate among flawless abrasive materials can be efficiently produced. Since the production method of the present invention is carried out by the solid phase reaction method, the manufacturing process is simpler than the spray pyrolysis method, and it is possible to realize low-cost production without introducing special equipment. Further, the composite metal oxide abrasive of the present invention can exhibit a good polishing rate and can sufficiently cope with the shortage of rare earth elements in recent years, and therefore can be considered as an industrially advantageous material.

Fig. 1-1 is a graph showing the results of differential thermal measurement of each of the zirconium compounds used in Example 1 and Comparative Example 1.

Figure 1-2 shows the thermogravimetric determination of each zirconium compound used in Example 1 and Comparative Example 1. A graph of the results.

Fig. 2-1 is a graph showing the results of differential heat measurement of each of the mixed powders (dried products of the mixture) of Example 1 and Comparative Example 1.

Fig. 2-2 is a graph showing the results of thermogravimetric measurement of the mixed powders (dried products of the mixture) of Example 1 and Comparative Example 1.

Fig. 3 is a graph showing the relationship between the zeta potential of each of the abrasive materials used in the reference example or the comparative reference example with respect to pH.

[Method of Manufacturing Composite Metal Oxide Abrasive Material]

The method for producing a composite metal oxide abrasive according to the present invention (also referred to as "the method for producing the present invention") comprises a step of mixing a mixed cerium compound and a zirconium compound, and calcining the mixture obtained by the mixing step. step. Therefore, a higher polishing speed of the composite metal oxide abrasive material can be achieved.

Further, as can be understood from the raw materials used, the production method of the present invention is carried out by a solid phase reaction method. Therefore, the manufacturing process is simpler than the spray pyrolysis method, and it is possible to realize low-cost manufacturing without introducing special equipment.

-raw material-

First, the ruthenium compound which is one of the raw materials in the production method of the present invention will be described.

The ruthenium compound is not particularly limited as long as it is a compound containing a ruthenium atom, and at least one selected from the group consisting of cesium carbonate and cesium hydroxide is preferable. Barium carbonate and barium hydroxide are easily reacted with a zirconium compound to easily form barium zirconate (SrZrO ₃ ).

Next, another raw material, that is, a zirconium compound will be described.

In the production method of the present invention, the amount of the SO ₃ equivalent of the sulfur compound contained in the zirconium compound is 2.0 parts by weight or less based on 100 parts by weight of the ZrO ₂ equivalent amount of the zirconium compound. When the content of the sulfur compound in the raw material zirconium compound is within this range, an abrasive material having an excellent polishing rate can be obtained. The content of the sulfur compound (SO ₃ equivalent amount) is preferably 1.5 parts by weight or less, more preferably 1.1 parts by weight or less, still more preferably 0.5 parts by weight or less.

The zirconium compound is not particularly limited as long as it is a compound containing a zirconium atom, and among them, zirconium oxide, zirconium carbonate, and zirconium hydroxide are preferable. These are highly reactive with ruthenium compounds and provide abrasive materials with better abrasive properties. Among them, a zirconium compound other than zirconia is preferably used, whereby the calcination and pulverization steps in the synthesis of zirconia can be omitted, and the production cost can be reduced and the production efficiency can be improved. That is, it is preferably at least one selected from the group consisting of zirconium carbonate and zirconium hydroxide.

The above zirconium compound preferably has a specific surface area of from 0.1 to 250 m ² /g. When the specific surface area is within this range, it becomes easy to efficiently produce a suitable crystalline SrZrO ₃ phase. For example, if the specific surface area of the zirconium compound is 0.1m ² / g or more, further enhance the reactivity of the strontium compound, and, if it is easy to 250m ² / g or less, and the reaction control becomes the strontium compound, and therefore in any In the case of the case, it is easy to obtain a composite metal oxide abrasive material having a good polishing rate. More preferably, it is 0.3 to 240 m ² /g, and further preferably 0.5 to 230 m ² /g.

In the present specification, the specific surface area (also referred to as SSA) means a BET specific surface area.

The BET specific surface area refers to a specific surface area obtained by a BET method which is one of the methods for measuring a specific surface area. Furthermore, the specific surface area refers to the surface area per unit mass of an object.

The BET method is a gas adsorption method in which gas particles such as nitrogen are adsorbed to solid particles and the specific surface area is measured by the amount of adsorption. Specifically, the relationship between the pressure P and the adsorption amount V is determined by the BET equation. The molecular adsorption amount VM, thereby determining the specific surface area.

- mixing step -

Next, the mixing step will be described.

The manufacturing method of the present invention comprises the step of mixing a mixture of a cerium compound and a zirconium compound. The ratio of the raw materials at the time of mixing is preferably SrO:ZrO ₂ =10:90 to 43:57 by weight ratio in terms of oxide. The method of mixing is not particularly limited, and may be wet mixing or dry mixing, but from the viewpoint of mixing, wet mixing is preferred. The dispersion medium used in the wet mixing is not particularly limited, and water or a lower alcohol can be used. From the viewpoint of production cost, water is preferred, and ion-exchanged water is more preferred. In the case of wet mixing, a ball mill or a paint conditioner or a sand mill can also be used. Further, it is preferred to carry out a drying step after wet mixing to remove the dispersion medium.

Further, the zirconium compound can be supplied to the mixing step in the form of a filter cake obtained in the synthesis.

- drying step -

After the above mixing step, the drying step can also be carried out as needed.

In the drying step, the dispersion medium is removed from the slurry obtained in the mixing step and allowed to dry. The method of drying the slurry is not particularly limited as long as the solvent used for the mixing can be removed, and examples thereof include drying under reduced pressure, drying by heating, and the like. Further, the slurry may be directly dried, or may be filtered and dried.

Further, the dried product of the mixture may be subjected to dry pulverization.

- calcination step -

Next, the calcination step will be described.

In the calcination step, the raw material mixture obtained by the mixing step (which may also be a dried product obtained by the drying step) is calcined. Thereby, a composite metal oxide abrasive material can be obtained. In the calcination step, the raw material mixture can be directly calcined, or can be formed into a specific shape (for example, granular) After the calcination. The calcination environment is not particularly limited. The calcination step may be carried out only once or twice or more.

The calcination temperature in the calcination step may be a temperature at which the reaction between the ruthenium compound and the zirconium compound is sufficiently carried out, and is preferably more than 800 ° C and not more than 1500 ° C. When the calcination temperature exceeds 800 ° C, the reaction proceeds more sufficiently, and the zirconium compound is easily crystallized to become zirconium oxide. When the calcination temperature is 1500 ° C or lower, the generated zirconate strontium is sufficiently suppressed from being strongly sintered. The grinding speed is further increased in any case. The lower limit of the calcination temperature is more preferably 850 ° C or higher. Thereby, the effects of the present invention can be more fully exerted. Further, it is preferably 900 ° C or higher, and particularly preferably 930 ° C or higher. Further, the upper limit is more preferably 1300 ° C or lower, further preferably 1200 ° C or lower.

In the present specification, the calcination temperature in the calcination step means the highest reaching temperature in the calcination step.

Here, in the case where a compound having a sulfur compound content exceeding the range set in the present invention is used as a raw material zirconium compound, the obtained grinding step is carried out even at the same calcination temperature as in the case of using the zirconium compound of the present invention. The crystallinity of the material is also insufficient, so that a good polishing speed cannot be obtained. Further, even if the crystallinity of the polishing material is made uniform by further increasing the firing temperature, a sufficient polishing rate cannot be obtained.

The holding time at the above calcination temperature may be a time period in which the reaction between the ruthenium compound and the zirconium compound is sufficiently carried out. For example, it is preferably from 5 minutes to 24 hours. When the holding time is within this range, the reaction proceeds more sufficiently. When the holding time is 24 hours or less, the calcined product (barium zirconate) is sufficiently suppressed from being strongly sintered, so that the polishing rate can be further increased. More preferably, it is 7 minutes to 22 hours, and further preferably 10 minutes to 20 hours.

In the above calcination step, it is preferred that the maximum temperature (calcination temperature) is reached. The temperature rise rate at the time of temperature rise is set to 0.2 to 15 ° C / min. When the temperature increase rate is 0.2° C./min or more, the time taken for the temperature rise is not excessively long, so that waste of energy and time can be sufficiently suppressed, and if it is 15° C./min or less, the temperature of the furnace contents can be adjusted. Fully following the set temperature, the calcination unevenness is more sufficiently suppressed. More preferably, it is 0.5 to 12 ° C / min, and further preferably 1.0 to 10 ° C / min.

- crushing step -

After the calcination step described above, the pulverization step can also be carried out as needed.

In the pulverization step, the calcined product obtained by the calcination step is pulverized. The pulverization method and the pulverization conditions are not particularly limited, and for example, a ball mill, a pulverizer, a hammer mill, a jet mill or the like can be used.

[Composite metal oxide abrasive material]

Next, the composite metal oxide abrasive of the present invention will be described.

The composite metal oxide abrasive of the present invention (hereinafter, also simply referred to as "abrasive material") is SO ₃ of a sulfur compound contained in the abrasive material (more specifically, a sulfur compound which enters the crystal of the abrasive material). The amount of the converted amount is 1.2 parts by weight or less based on 100 parts by weight of the ZrO ₂ equivalent amount of the zirconium compound contained in the composite metal oxide abrasive. When the content of the sulfur compound is within this range, it becomes an abrasive material having an excellent polishing rate. The content of the sulfur compound is preferably 1.0 part by weight or less, more preferably 0.8 part by weight or less, still more preferably 0.6 part by weight or less.

The above abrasive material is preferably obtained by the production method of the above invention.

The polishing material is preferably a crystal phase containing ZrO ₂ and a crystal phase of SrZrO ₃ . The crystal phase of ZrO ₂ contained in the abrasive material is responsible for mechanical grinding, and the crystal phase of SrZrO ₃ is responsible for chemical polishing, whereby a more excellent polishing speed can be exhibited. Further, the abrasive of the present invention is preferably a composite of ZrO ₂ and SrZrO ₃ , whereby the polishing rate can be further increased. Further, the composite system of SrZrO ₃ and ZrO ₂ refers to a secondary particle formed by partial sintering of primary particles of each of SrZrO ₃ and zirconia. For example, when the composite is subjected to elemental mapping by energy dispersive X-ray analysis (EDS), it is observed that primary particles of Sr and Zr and primary particles of only Zr are detected to form secondary particles.

Preferably, the abrasive material has a full width at half maximum of a peak from the (040) plane of the orthorhombic SrZrO ₃ in the X-ray diffraction using CuK α ray as a radiation source of 0.1 to 3.0°. When the full width at half maximum is within this range, the crystallinity of SrZrO ₃ which effectively exhibits a chemical polishing action is suitable, so that the chemical polishing action can be sufficiently exhibited. In addition, when the full width at half maximum exceeds 3.0°, the crystallinity of SrZrO _{3 may} be insufficient. When the full width at half maximum is less than 0.1°, the crystallinity of SrZrO _{3 may} be excessively high. In the case of the case, the chemical polishing action by SrZrO ₃ cannot be sufficiently obtained. More preferably, it is 0.1 to 1.0 °, further preferably 0.1 to 0.7 °, and particularly preferably 0.1 to 0.4 °.

Preferably, the abrasive material has a ratio of D ₉₀ to D ₁₀ (D ₉₀ /D ₁₀ ) which is an index of sharpness of the volume-based particle size distribution of 1.5 to 50. To D ₉₀ / D ₁₀ of more than 50 case, due to the presence of differences in particle diameter is too large, it can not be sufficiently obtained abrasive material contacting the polished of the object, resulting in the case of insufficient polishing rate. When the D ₉₀ /D _{10 is} less than 1.5, the difference in particle diameter is too small, and the contact between the abrasive material and the object to be polished may not be sufficiently obtained, resulting in insufficient polishing rate.

Further, the larger D ₉₀ /D ₁₀ means that the wider the particle size distribution, the smaller the value means the steeper the particle size distribution.

D ₁₀ and D ₉₀ are values obtained by measuring the particle size distribution, respectively. D ₁₀ means 10% cumulative particle size on a volume basis, and D ₉₀ means 90% cumulative particle size on a volume basis.

The above-mentioned polishing material preferably contains Sr in an amount of 10 to 43% by weight in terms of SrO. When the Sr content is less than 10% by weight in terms of SrO, the content of SrZrO ₃ is lowered, and the chemical polishing effect cannot be sufficiently obtained. In addition, when the Sr content is more than 43% by weight in terms of SrO, the content of ZrO ₂ is relatively lowered, and the mechanical polishing action cannot be sufficiently obtained. More preferably, it is 11 to 43% by weight, and further preferably 12 to 43% by weight.

The above abrasive material preferably has a specific surface area of 1.0 to 50 m ² /g. When the specific surface area is less than 1.0 m ² /g, the specific surface area of the abrasive material is too small to be sufficiently in contact with the object to be polished, resulting in insufficient polishing. Further, when the specific surface area exceeds 50 m ² /g, the abrasive grains constituting the abrasive material are too small to sufficiently obtain the mechanical polishing action. More preferably 1.0 ~ 45m ² / g, and further preferably 1.0 ~ 40m ² / g.

The abrasive material of the present invention can be applied to various abrasive objects. For example, it can be applied to conventional polishing using cerium oxide, chromium oxide, and iron oxide (Fe ₂ O ₃ ) as an abrasive. The object to be polished is not particularly limited, and examples thereof include a glass substrate, a metal plate, stone, sapphire, tantalum nitride, tantalum carbide, niobium oxide, gallium nitride, gallium arsenide, indium arsenide, and indium phosphide.

The above-mentioned polishing material may be suitably used in combination with other components depending on the application. For example, the abrasive material of the present invention may be mixed with a dispersion medium, may be mixed with an additive, or may be mixed with a dispersion medium and an additive at the same time. The form when it is mixed with the dispersion medium and/or the additive is not particularly limited, and for example, it can be used in the form of a powder, a paste, or a slurry.

The dispersion medium is not particularly limited, and examples thereof include water, an organic solvent, and a mixture thereof. These may be used alone or in combination of two or more. Examples of the organic solvent include alcohol, acetone, dimethyl hydrazine, dimethylformamide, tetrahydrofuran, and Examples of the alcohol include a monohydric water-soluble alcohol such as methanol, ethanol or propanol; a water-soluble alcohol of two or more types such as ethylene glycol or glycerin. As the dispersion medium, water is preferred, and ion exchange water is more preferred.

The additive is not particularly limited, and examples thereof include an acid, a base, a pH adjuster, a chelating agent, an antifoaming agent, a dispersing agent, a viscosity adjusting agent, an anti-agglomerating agent, a lubricant, a reducing agent, and a rust preventive agent. Agent, known abrasive materials, and the like. One or two or more kinds of these additives may be used in combination in the range which does not impair the effects of the present invention.

[grinding method]

Next, an example of a polishing method using the composite metal oxide abrasive of the present invention will be described.

The composite metal oxide abrasive of the present invention can be applied to various polishing targets as described above, and in the case where a negatively chargeable substrate is used as a polishing target, it is preferably applied to the following polishing method. Further, the polishing method using the composite metal oxide abrasive of the present invention is not limited to the following polishing methods.

In other words, the polishing method is performed at least once, and the negative charging is performed under the condition that the zeta potential of the slurry containing the composite metal oxide abrasive of the present invention (hereinafter also referred to as the polishing slurry) becomes positive. The polishing step a of the substrate and the polishing step b of polishing the negatively charged substrate under the condition that the zeta potential of the slurry is negative.

In the present specification, the negatively-chargeable substrate is preferably a substrate which is negatively charged in an aqueous solution having a pH of more than 4, and examples thereof include a glass substrate (the isoelectric point of the glass is about 2.0). Further, a tantalum carbide substrate (the isoelectric point of tantalum carbide is about 4.0) or the like may be mentioned.

In addition, examples of the glass substrate include transparent or translucent crystals such as soda lime glass, alkali-free glass, borosilicate glass, and quartz glass.

In the above polishing method, the polishing step a of polishing the negatively-charged substrate is performed under the condition that the zeta potential of the polishing slurry is positive, and the zeta potential of the slurry is negative in at least one step. The grinding step b of grinding the negatively charged substrate under conditions. The order of the polishing steps is not particularly limited, and the polishing step b may be performed after the polishing step a, or may be performed in the polishing step b. Thereafter, the grinding step a is performed. Among them, in order to obtain a negatively-chargeable substrate excellent in surface smoothness, it is particularly preferable to perform at least one polishing step b after performing at least one polishing step a. Further, each polishing step may be performed a plurality of times, and the polishing step a and the polishing step b may be alternately performed. When the polishing step a is performed a plurality of times, as long as the zeta potential of the polishing slurry is positive, the zeta potential may be changed or may be carried out without change. The same applies to the case where the polishing step b is performed a plurality of times. As long as the zeta potential of the polishing slurry is negative, the zeta potential can be changed or carried out without change.

In the present specification, the "ζ potential of the polishing slurry" is a value obtained under the measurement conditions described in Examples to be described later.

In the above polishing method, the polishing material acts as an electrostatic attraction force in the polishing step a, and functions as an electrostatic repulsion in the polishing step b. Therefore, it is presumed that a high polishing rate and polishing can be achieved by utilizing the synergistic effects. Excellent surface smoothness of the latter negatively charged substrate. Usually, a concave portion composed of fine damage or a hole or the like is present on the surface of the negatively-charged substrate before polishing. In the polishing step a, it is considered that since the substrate to be polished is negatively charged, the polishing slurry is positively charged. Therefore, the polishing material penetrates into the depth of the concave portion by electrostatic attraction to promote polishing, so that the polishing speed is obtained. improve. On the other hand, in the polishing step b, it is considered that the substrate to be polished and the polishing slurry are negatively charged, so that the abrasive does not penetrate deep into the concave portion due to the electrostatic repulsion, but by the polishing pad and the substrate Pressure is applied therebetween, and the abrasive material is present in a large number of convex portions on the surface of the substrate, thereby smoothing the surface of the substrate. Therefore, as long as the object to be polished is a negatively charged substrate, the same mechanism of action is obtained. Therefore, the above polishing method can be applied not only to a glass substrate but also to various negatively charged substrates.

Any of the above-described polishing step a and polishing step b is performed in the presence of a polishing slurry. In the grinding step a and the grinding step b, the same abrasive slurry can be used, that is, Continuous use (reuse), only the zeta potential of the slurry is controlled, and the slurry slurry having a positive or negative zeta potential may be prepared differently, and the polishing slurry may be switched in each polishing step. In any case, the composite metal oxide abrasive material of the present invention may be used as the polishing material slurry. In the polishing method as described above, the polishing slurry can be continuously used (recycled), and it is not necessary to prepare a polishing slurry having a large difference in type even in the case of switching, so that it is not necessary to switch the polishing material as in the conventional method. Washing operations or special equipment necessary for the time. Further, even if it is not necessary to use cerium oxide, a high polishing rate and excellent surface smoothness can be achieved, and thus the above polishing method is considered to be a very advantageous method as compared with the conventional polishing method.

The polishing step a is a step of polishing the negatively-charged substrate using the abrasive slurry under the condition that the zeta potential of the polishing slurry is positive. In the polishing step, it is possible to achieve a higher polishing rate substantially the same as that of the conventional use of the cerium oxide-based abrasive, and it is also possible to improve the surface smoothness of the negatively-charged substrate as compared with the case of using the yttrium-based abrasive. Sex.

The polishing step b is a step of polishing the negatively-charged substrate using the abrasive slurry under the condition that the zeta potential of the polishing slurry is negative. In the grinding step, a polishing speed which is significantly higher than the conventional precision grinding step using colloidal silica can be achieved, and at the same time, a precision grinding which is substantially equivalent to the precision grinding step using colloidal cerium oxide can be carried out. Higher surface smoothness is achieved in the negatively charged substrate after grinding.

As described above, the negatively charged substrate is ground in the polishing step a under the condition that the zeta potential of the abrasive slurry becomes positive, and the negatively charged substrate is ground in the polishing step b under the condition that the zeta potential of the abrasive slurry becomes negative. The substrate is preferably subjected to each polishing step under the condition that the absolute value of the zeta potential of the polishing slurry is 5 mV or more. More preferably, it is 10 mV or more, further preferably 15 mV or more, and particularly preferably 20 mV or more. The upper limit of the absolute value in each step is not particularly limited, for example, It is easy to control (for example, if the zeta potential is too large in the polishing step a, there is a possibility that the polishing material remains on the surface of the glass substrate, and this is prevented. For example, if the zeta potential is too small in the polishing step b, In the case where the electrostatic repulsion of the negatively-charged substrate and the polishing slurry is too strong to sufficiently increase the polishing rate, it is preferably 100 mV or less from the viewpoint of preventing this.

The zeta potential of the abrasive slurry can be controlled by adjusting the pH of the abrasive slurry. When the abrasive slurry contains the composite metal oxide abrasive of the present invention, when the pH of the slurry slurry is adjusted to be below the isoelectric point of the slurry slurry, the zeta potential becomes positive, and the other On the other hand, when the pH of the abrasive slurry is adjusted to exceed the range of the isoelectric point of the abrasive slurry, the zeta potential becomes negative. Further, in the conventional polishing material, the polishing rate is increased, or the surface smoothness is improved. However, the composite metal oxide polishing material of the present invention can easily control the polishing property only by the pH value, and in this respect, Exercising the specific effects that cannot be conceived by conventional techniques.

The adjustment of the pH value can be carried out by adding a pH adjuster to the polishing slurry, and the pH of the polishing slurry can also be adjusted using a pH buffer.

Further, when the pH of the abrasive slurry is already in the range of preferably the polishing, the pH adjustment may not be performed.

As the pH adjuster, an acid or a base can be used. When an acid is used, the pH of the polishing slurry can be adjusted to the acidic side, and if a base is used, the pH of the polishing slurry can be adjusted to the alkaline side. The acid is, for example, preferably an inorganic acid such as nitric acid, sulfuric acid, hydrochloric acid, perchloric acid or phosphoric acid; an organic acid such as oxalic acid or citric acid; and as the base, for example, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution or a calcium hydroxide is preferred. An alkaline aqueous solution such as an aqueous solution, an aqueous solution of sodium carbonate, an aqueous solution of ammonia or an aqueous solution of sodium hydrogencarbonate.

In the above grinding method, preferably, the pH of the abrasive slurry is greater than the above negative The polishing step a is carried out under the condition that the isoelectric point of the charged substrate does not reach the isoelectric point of the abrasive slurry. Thereby, the composite metal oxide abrasive of the present invention is sufficiently inhibited from being dissolved by a strong acid, and the polishing action of the abrasive is further exerted, and the burden on the polishing machine and the apparatus can be reduced. The lower limit of the pH of the polishing slurry in the polishing step a is specifically preferably 2 or more. More preferably, it is 3 or more, More preferably, it is 4 or more.

Moreover, it is preferable to perform the polishing step b under the condition that the pH of the polishing slurry is larger than the isoelectric point of the polishing slurry and is 13 or less. Thereby, the composite metal oxide polishing material of the present invention is sufficiently inhibited from being dissolved by a strong alkali, and the polishing action of the polishing material is further exerted, and the burden on the polishing machine and the apparatus can be reduced. The upper limit of the pH of the polishing slurry in the polishing step b is preferably 12 or less. More preferably, it is 11 or less.

The isoelectric point of the abrasive slurry (and the composite metal oxide abrasive of the present invention) means that the algebraic charge of the abrasive particles (the composite metal oxide abrasive of the present invention) in the abrasive slurry is The point zero, that is, the point at which the positive and negative charges of the abrasive particles become equal, can be expressed by the pH of the slurry slurry at that point.

In the above-mentioned abrasive slurry, the content of the composite metal oxide abrasive of the present invention is preferably 0.001 to 90% by weight, for example, in 100% by weight of the abrasive slurry. More preferably, it is 0.01 to 30% by weight. Moreover, it is preferable that the said abrasive slurry further contains a dispersion medium. The dispersion medium is as described above.

[Examples]

In order to explain the present invention in detail, the examples are exemplified below, but the invention is not limited to the embodiments.

Example 1

(1) Zr raw material preparation steps

3.0 kg of zirconium oxychloride octahydrate (manufactured by Showa Chemical Co., Ltd.) was dissolved in 6.7 L of ion-exchanged water while stirring. While stirring the solution, the solution was adjusted to 25 ° C, and the temperature was maintained. After stirring for 1 hour, a 180 g/L sodium hydroxide aqueous solution was added until the pH became 9.5, and the mixture was further stirred for 1 hour. The slurry was filtered and washed with water, and washed with water until the conductivity of the washing liquid became 100 μS/cm or less, whereby a zirconium hydroxide filter cake was obtained.

(2) mixing step

26.1 g of cesium carbonate (manufactured by Suga Chemical Industry Co., Ltd.: SW-PN) as a raw material of Sr, and 31.3 g of ZrO ₂ as a Zr raw material were obtained by the (1) Zr raw material preparation step. Zirconium hydroxide filter cake and placed in 300mL cannabis bottle, add 172mL ion exchange water and 415g of 1mm The zirconia beads were mixed for 30 minutes using a paint conditioner (manufactured by Red Devil Co., Ltd.: Model 5110).

(3) Drying step

The slurry obtained by the above (2) mixing step is placed on a sieve of 400 mesh (mesh 38 μm) to remove the zirconia beads, and then the filter cake of the mixture obtained by filtration is fully formed at a temperature of 120 ° C. Drying, thereby obtaining a dried product of the mixture.

(4) Calcination step

30 g of the dried product of the mixture obtained by the above (3) drying step was placed in an alumina crucible having an outer diameter of 55 mm and a capacity of 60 mL, and calcined using an electric burning furnace (manufactured by ADVANTEC, KM-420). , a calcined product is obtained. The calcination conditions were raised from room temperature to 950 ° C over 285 minutes and held at 950 ° C for 180 minutes, after which the heater was energized and cooled to room temperature. Further, calcination is carried out in the atmosphere.

(5) pulverization step

10 g of the calcined product obtained by the above (4) calcination step was placed in an automatic mortar (manufactured by Nitto Scientific Co., Ltd.: ANM-150), and pulverized for 10 minutes, thereby obtaining a composite metal. Oxide abrasive material.

Example 2, 3

The composite metal oxide abrasive was obtained in the same manner as in Example 1 except that the calcination temperature in the (4) calcination step was changed to the temperature shown in Table 1.

Example 4

(1) Zr raw material preparation steps

3.0 kg of zirconium oxychloride octahydrate (manufactured by Showa Chemical Co., Ltd.) and 0.35 kg of ammonium sulfate (manufactured by Toagosei Co., Ltd.) were dissolved in 6.7 L of ion-exchanged water while stirring. While stirring the solution, the solution was adjusted to 25 ° C, and the temperature was maintained. After stirring for 1 hour, a 180 g/L sodium hydroxide aqueous solution was added until the pH became 9.5, and the mixture was further stirred for 1 hour. The slurry was filtered and washed with water, and washed with water until the conductivity of the washing liquid became 100 μS/cm or less, whereby a zirconium hydroxide filter cake was obtained.

(2) Drying Step - (5) The pulverizing step was carried out in the same manner as in Example 1 to obtain a composite metal oxide abrasive.

Example 5

A composite metal oxide abrasive was obtained in the same manner as in Example 1 except that 109 g of zirconium carbonate (manufactured by Ba Industrial Co., Ltd.) was used as the Zr raw material in the (2) mixing step.

Example 6

Using 69 g of zirconium carbonate (manufactured by Ba Industrial Co., Ltd.) as (2) Zr in the mixing step A composite metal oxide abrasive was obtained in the same manner as in Example 1 except for the above.

Comparative example 1

(1) Zr raw material preparation steps

3.0 kg of zirconium oxychloride octahydrate (manufactured by Showa Chemical Co., Ltd.) and 0.70 kg of ammonium sulfate (manufactured by Toagosei Co., Ltd.) were dissolved in 6.7 L of ion-exchanged water while stirring. The solution was adjusted to 25 ° C while stirring, and the temperature was maintained, and a 180 g/L sodium hydroxide aqueous solution was added while stirring for 1 hour until the pH became 9.5, and the mixture was further stirred for 1 hour. The slurry was filtered and washed with water, and washed with water until the conductivity of the washing liquid became 100 μS/cm or less, whereby a zirconium hydroxide filter cake was obtained.

(2) Drying Step - (5) The pulverizing step was carried out in the same manner as in Example 1 to obtain a comparative abrasive.

Comparative example 2

The comparative abrasive material was obtained in the same manner as in Example 1 except that the zirconium hydroxide cake obtained in the (1) Zr raw material preparation step was dried at 130 ° C for 15 hours.

Comparative example 3, 4

The polishing material for comparison was obtained in the same manner as in Comparative Example 2 except that the firing temperature in the (4) calcination step was changed to the temperature shown in Table 1.

<Performance evaluation>

The properties of the abrasive materials and the raw materials produced in the respective examples and comparative examples were evaluated in the following order.

(i) Determination of full width at half maximum

Each of the Zr raw material (zirconium compound) and the abrasive material was measured for the powder X-ray diffraction pattern (also simply referred to as an X-ray diffraction pattern) under the following conditions.

Using the machine: Rigaku Co., Ltd. manufactures RINT-UltimaIII

Radioactive source: CuK α

Voltage: 40kV

Current: 40mA

Sample rotation speed: no rotation

Divergence slit: 1.00mm

Divergence longitudinal limit slit: 10mm

Scattering slit: open

Light receiving slit: open

Scan mode: FT

Counting time: 2.0 seconds

Step distance: 0.0200°

Operating axis: 2 θ / θ

Scan range: 10.0000~70.0000°

Cumulative number: 1 time

Monoclinic ZrO ₂ : JCPDS card 00-037-1484

Square crystal ZrO ₂ : JCPDS card 00-050-1089

Cubic ZrO _2: JCPDS Card 00-049-1642

Orthorhombic SrZrO ₃ : JCPDS Card 00-044-0161

Thereafter, the rhombohedral SrZrO ₃ (040) full width at half maximum was measured based on the diffraction pattern obtained by the measurement of the X-ray diffraction of the abrasive obtained in each of the examples and the comparative examples. The results are shown in Table 2.

Further, using CuK α ray radiation source of the X-ray diffraction, the maximum peak of monoclinic ZrO ₂ i.e. from the (-111) face of the peak near 2 θ = 28.14 °, the maximum peak of tetragonal ZrO ₂ of That is, the peak from the (011) plane is located near 2 θ=30.15°, the peak of the cubic ZrO _{2 is} the peak from the (111) plane at 2 θ=30.12°, and the orthorhombic SrZrO ₃ is from the (040) plane. The peak is located near 2 θ=44.04°.

(ii) Elemental analysis

Each of the Zr raw material (zirconium compound) and the abrasive material was subjected to elemental analysis by an EZ scan containing an elemental scanning function by a fluorescent X-ray analyzer (manufactured by Rigaku Co., Ltd.: model ZSX Primus II).

Specifically, the pressurized sample was placed on the measurement sample stage, and the following conditions were selected (measurement range: FU, measurement diameter: 30 mm, sample form: oxide, measurement time: long; environment: vacuum), thereby The content of SO ₃ in the Zr raw material and the Sr content (in terms of SrO) and the SO ₃ content in the abrasive material were measured. The results are shown in Table 2.

Based on the SO ₃ content in the Zr raw material obtained in this manner, the SO ₃ content (parts by weight) based on 100 parts by weight of the ZrO ₂ equivalent amount of the Zr raw material was calculated. This is shown in the column "SO ₃ ^*1 (parts by weight)" in Table 2.

In addition, based on the SO ₃ content in the polishing material obtained as described above, the SO ₃ content (parts by weight) based on 100 parts by weight of the ZrO ₂ equivalent amount of the zirconium compound contained in the polishing material was calculated. This is shown in the column "SO ₃ ^{* 2} (parts by weight)" in Table 2.

(iii) Determination of specific surface area

For each of the Zr raw material (zirconium compound) and the abrasive, the specific surface area was measured under the following conditions. The results are shown in Table 2.

Use machine: Mosorbtech Co., Ltd. manufactures Macsorb Model HM-1220

Environment: nitrogen (N ₂ )

Degassing condition of external degassing device: 200 ° C - 15 min

Degassing condition of the body of the specific surface area measuring device: 200 ° C - 5 min

(iv) Sharpness of particle size distribution (D ₉₀ /D ₁₀ )

For the abrasive material, the particle size distribution measurement was performed using a laser diffraction and scattering particle size analyzer (manufactured by Nikkiso Co., Ltd.: model Microtrac MT3300EX).

First, 60 mL of ion-exchanged water was added to 0.1 g of the abrasive, and the mixture was thoroughly stirred at room temperature with a glass rod to prepare a suspension of the abrasive. Furthermore, the dispersion operation using ultrasonic waves is not performed. Thereafter, 180 mL of ion-exchanged water was prepared in a sample circulator, and the suspension was added dropwise so that the transmittance was 0.71 to 0.94, and the flow rate was 50%, and the ultrasonic wave was not dispersed and circulated and measured.

(v) Differential thermal-thermal gravimetric determination of zirconium compounds (zirconium hydroxide)

In order to investigate the reason why the polishing rate of the abrasive material was lowered when the sulfur compound was contained in the zirconium compound, the Zr raw materials (zirconium hydroxide) used in Example 1 and Comparative Example 1 were subjected to 130 ° C at 130 ° C. After drying for 12 hours, differential thermal-thermogravimetric analysis (TG/DTA) was performed.

Specifically, differential thermo-thermogravimetric measurement (TG/DTA) was carried out under the following conditions. The measurement results are shown in Fig. 1-1 and Fig. 1-2. The dried product of the mixture obtained in the "(3) drying step of Example 1 and the dried product of the mixture obtained in the "(3) drying step" of Comparative Example 1 were similarly advanced. Differential thermal-thermogravimetric determination (TG/DTA). The measurement results are shown in Fig. 2-1 and Fig. 2-2.

Measuring machine: manufactured by Rigaku Co., Ltd., differential heat-thermal weight measuring device (Model: Thermo plus EVO2 TG8121)

Heating rate: 10 ° C / min

Measuring temperature range: 30~1200°C

Measurement environment: atmosphere 200mL / min

Reference value: Al ₂ O ₃

Sample weight: 10.0mg

Sample container: platinum

(vi) Glass plate grinding test

1. First, an abrasive slurry is prepared using each of the abrasive materials.

Specifically, the abrasive is added to the ion-exchanged water so that the concentration of the abrasive is 5.0% by weight. Further, the mixture was stirred at 25 ° C for 10 minutes to be dispersed to prepare a water-dispersed abrasive slurry.

2. Next, the glass plate was polished using each of the abrasive materials in accordance with the following conditions.

Use glass plate: soda-lime glass (manufactured by Songlang Glass Industry Co., Ltd., size 36×36×1.3mm specific gravity 2.5g/cm ³ )

Grinding machine: desktop grinding machine (manufactured by MAT Co., Ltd., MAT BC-15C, grinding plate diameter 300mm )

Grinding pad: foamed polyurethane pad (manufactured by NITTA.HAAS Co., Ltd., MHN-15A, not impregnated with barium oxide)

Grinding pressure: 101g/cm ²

Fixed number of revolutions: 70rpm

Supply of abrasive composition: 100mL/min

Grinding time: 60min

3. The weight of the glass plate before and after the glass plate grinding test was measured by an electronic balance. The amount of decrease in the thickness of the glass plate was calculated from the weight reduction amount, the area of the glass plate, and the specific gravity of the glass plate, and the polishing rate (μm/min) was calculated.

At the same time, three glass plates were ground, and the glass plate and the abrasive slurry were exchanged after grinding for 60 minutes. This operation was carried out three times, and the average of the polishing rates of a total of nine sheets was taken as the value of the polishing rate in each of the examples and the comparative examples, and the results are shown in Table 2.

When the polishing rate is 0.29 μm/min or more, it is excellent (?), and if it is 0.22 μm/min or more and less than 0.29 μm/min, it is good (○), and if it is less than 0.22 μm/min, it is not preferable ( ×).

In Table 2, "SO ₃ ^*1 (parts by weight)" means the SO ₃ equivalent amount of the sulfur compound contained in the Zr raw material in terms of ZrO ₂ equivalent amount of the Zr raw material (zirconium compound), "SO ₃ ^*2 (parts by weight) means the SO ₃ equivalent amount of the sulfur compound contained in the abrasive material in an amount of 100 parts by weight based on the ZrO ₂ of the zirconium compound contained in the abrasive.

According to the above examples and comparative examples, the following cases were confirmed.

The zirconium compound used in Example 1 and the zirconium compound used in Comparative Example 1 differ mainly in the content of the sulfur compound.

If the results of the differential thermal-thermogravimetric measurement are compared based on the difference, it is observed that any zirconium compound (zirconium hydroxide) has an exothermic change without weight change according to FIGS. 1-1 and 1-2. crest. In this case, the amorphous zirconium hydroxide is a main component at a temperature lower than the exothermic peak, and zirconium hydroxide is crystallized into zirconium oxide at the temperature of the exothermic peak. However, the exothermic peak of zirconium hydroxide used in Example 1 is The exothermic peak of zirconium hydroxide used in Comparative Example 1 at 416 ° C was 506 ° C. Therefore, it is understood that the zirconium hydroxide used in Comparative Example 1 has a higher temperature required for crystallization than the zirconium hydroxide used in Example 1, that is, it is difficult to crystallize at the same calcination temperature.

2-1 and 2-2 show differential heat of a dry product (referred to as a mixed powder) of a mixture of a zirconium compound (zirconium hydroxide) and a cerium compound (cerium carbonate) used in Example 1 or Comparative Example 1. - A graph of the results of the thermogravimetric measurement. According to Fig. 2, it was observed that any of the mixed powders had an exothermic peak which was not accompanied by a change in weight. From the difference in peak temperature, it was found that the mixed powder of Comparative Example 1 was required for crystallization as compared with the mixed powder of Example 1. The temperature is higher, that is, it is difficult to crystallize at the same calcination temperature.

Thus, the reason why the temperature of the exothermic peak is different is that since the amount of the sulfur compound contained in the zirconium hydroxide used in Comparative Example 1 exceeds the range specified in the present invention, the crystallinity of the finally obtained abrasive material is also obtained. Have an impact. According to Table 2, the full width at half maximum of the peak from the (040) plane of the orthorhombic SrZrO ₃ of the abrasive of Comparative Example 1 and the SSA were increased as compared with the composite metal oxide abrasive of Example 1. It shows that the abrasive material in the case of calcination at 950 ° C has a low crystallinity. Further, it was confirmed that there was a significant difference in the polishing rate between Comparative Example 1 and Example 1. Therefore, it is considered that if the content of the sulfur compound contained in the zirconium compound exceeds the range specified in the present invention, the crystallinity of the abrasive material is lowered, and the polishing rate is lowered.

The abrasive materials of Comparative Examples 3 to 4 increased the calcination temperature as compared with Example 1, thereby improving the crystallinity. However, according to Table 2, although the half-height width of the peak from the (040) plane of the orthorhombic SrZrO ₃ of the abrasive materials of Comparative Examples 3 and 4 and the peak of the SSA and the composite metal oxide abrasive material of Example 1 The height and width are the same as the SSA, but the grinding speed is low. It is presumed that the reason is that although the crystallinity of the abrasive material is increased to the same extent by increasing the calcination temperature, the particles are excessively sintered. Further, the abrasive material of Comparative Example 2 was supplied to the mixed material with the cerium compound (cerium carbonate) after drying the zirconium compound (zirconium hydroxide) at 130 ° C, and was different from the abrasive material of Example 1, according to Table 2, In this case as well, since the amount of the sulfur compound contained in the zirconium compound exceeds the range specified in the present invention, the polishing rate does not reach a sufficient level.

From the above, it is understood that the production method of the present invention can efficiently provide an abrasive material having a good polishing rate among flawless abrasive materials.

Reference example 1

Using the composite metal oxide abrasive obtained in Example 1, a slurry slurry A was produced.

Specifically, 20.0 g of the abrasive was dispersed in 380.0 g of ion-exchanged water and stirred at 25 ° C for 10 minutes. The abrasive slurry A was thus obtained.

The zeta potential was measured for the polishing slurry A according to the following conditions. Grinding slurry The relationship between the zeta potential and the pH is shown in Figure 3. Further, the isoelectric point of the abrasive slurry A was 6.2. Here, the isoelectric point means that the algebra of the electric charge carried by the abrasive grains (composite metal oxide abrasive material) in the abrasive slurry is zero, that is, the positive and negative charges of the abrasive grains become The point of equalization can be expressed by the pH of the abrasive slurry in this point.

(Measurement conditions of zeta potential)

Measuring machine: manufactured by Otsuka Electronics Co., Ltd., zeta potential measuring system, model ELSZ-1

pH titrator: manufactured by Otsuka Electronics Co., Ltd., model ELS-PT

6 g of the abrasive slurry was diluted 5 times with ion-exchanged water, and the mixture was stirred by a glass rod while being dispersed by an ultrasonic cleaner for 1 minute. 50 cc of ion-exchanged water was added to 10 cc of this slurry, and the intensity was set to V-LEVEL3 by the ultrasonic homogenizer (US-600, manufactured by Nippon Seiki Co., Ltd.), and the dispersion treatment was performed for 1 minute. 30 cc of the zeta potential measurement slurry slurry obtained in this manner was filled in a zeta potential measuring machine.

In addition, the abrasive slurry C using the colloidal cerium oxide described later is subjected to an ultrasonic homogenizer (US-600, manufactured by Nippon Seiki Co., Ltd.), and the strength is set to V-LEVEL3 to 60 cc of the abrasive slurry C. Minute dispersion processing. 30 cc of the zeta potential measurement slurry slurry obtained in this manner was filled in a zeta potential measuring machine.

Further, in order to adjust the pH of the polishing slurry, the following pH adjusting agent is used as needed.

Acid side pH adjustment solution: aqueous hydrochloric acid solution, 0.1mol/L

Alkaline side pH adjustment solution: aqueous sodium hydroxide solution, 1 mol/L

(1) First grinding step

The zeta potential of the abrasive slurry A obtained as described above is the value shown in Table 3. The pH of the slurry is adjusted. In the presence of the slurry, the glass plate was polished under the same polishing conditions as in the "(vi) glass plate polishing test" of Example 1, and the polishing rate was measured. The polishing rate in this step and the pH value of the polishing slurry A are shown in Table 3. Further, the surface roughness of the glass substrate after the first polishing step was evaluated by the following method. The results are shown in Table 3.

(2) Second grinding step

After the first polishing step, the abrasive slurry A is taken out, and replaced with a new abrasive slurry A, and the pH of the slurry is adjusted so that the zeta potential becomes the value shown in Table 3, and then In the presence of the slurry, the glass substrate was polished under the same polishing conditions as in the first polishing step, and the polishing rate was measured. The polishing rate in this step and the pH value of the polishing slurry A are shown in Table 3. Further, the surface roughness of the glass substrate after the second polishing step was evaluated by the following method. The results are shown in Table 3.

(Measurement of surface smoothness of glass substrate)

The surface roughness of the glass plate after each polishing step was measured according to the following conditions.

Measuring machine: manufactured by ZYGO Co., Ltd., white interference microscope, model NewView ^TM 7100

Horizontal resolution: <0.1nm

Objective lens: 50 times

Filter: None

Measuring field size: X = 186 μm, Y = 139 μm

Evaluation method: For the polished glass substrate, the center point and the Ra of 9 points from the intersection of the concentric circles having the center point radius of 6 mm and 12 mm and the diagonal of the glass substrate were measured, and the average value was calculated. This operation was performed on a total of nine glass substrates used for the measurement of the polishing rate described above, and the average value of Ra of each glass substrate was averaged to evaluate the surface roughness.

Comparative reference example 1

(1) First grinding step

An oxidized enamel polishing material for glass polishing (manufactured by Showa Denko Co., Ltd., SHOROX (R) A-10, yttria content: 60% by weight, isoelectric point: 10.4) was used as a polishing material, and other examples were given. 1 The abrasive slurry B was produced in the same manner. After adjusting the pH of the slurry so that the zeta potential of the abrasive slurry B becomes the value shown in Table 3, in the presence of the slurry, in "vi with Example 1" The glass plate was ground under the same polishing conditions as in the "glass plate polishing test", and the polishing rate was measured. The polishing rate in this step and the pH value of the polishing slurry B are shown in Table 3. Further, the surface roughness of the glass substrate after the first polishing step was evaluated in the same manner as in Reference Example 1. The results are shown in Table 3.

(2) Second grinding step

The polishing slurry B used in the first polishing step is taken out from the polishing machine and washed by a polishing machine.

Separately, 52.2 g of colloidal cerium oxide (Fussan Chemical Co., Ltd., Quartron (R) PL-7, isoelectric point: 5.8) was dispersed in 347.8 g of ion-exchanged water, and stirred at 25 ° C for 10 minutes. This was prepared as the abrasive slurry C. After adjusting the pH value so that the zeta potential of the separately prepared polishing material slurry C becomes the value shown in Table 3, it is the same as the first polishing step in the presence of the polishing material slurry C. The polishing of the glass substrate was carried out under grinding conditions. The pH of the abrasive slurry C in this step is shown in Table 3. Moreover, the polishing rate in the second polishing step and the surface roughness of the glass substrate after the second polishing step were evaluated in the same manner as in Reference Example 1. The results are shown in Table 3.

In addition, the relationship between the zeta potential of each of the abrasive slurry B and C with respect to pH is shown in FIG.

According to the above Reference Example 1 and Comparative Reference Example 1, the following cases were confirmed.

In Reference Example 1 and Comparative Reference Example 1, although the surface roughness of the finally obtained substrate (substrate after the second polishing step) was substantially the same, in Reference Example 1, the polishing rate was remarkable as compared with Comparative Reference Example 1. improve. Therefore, it is understood that the above-described preferred polishing method (that is, a polishing method in which at least one of the following steps is performed: polishing of a negatively-charged substrate under conditions in which the zeta potential of the slurry containing the composite metal oxide abrasive of the present invention becomes positive The step a) and the polishing step b) of polishing the negatively-charged substrate under the condition that the zeta potential of the abrasive slurry becomes negative can achieve a higher polishing speed and excellent surface smoothness in the flawless abrasive material. In addition, in Comparative Reference Example 1, since the cerium oxide-based abrasive is used in the first polishing step and the colloidal cerium oxide is used in the second polishing step, it is necessary to perform a cleaning operation of the polishing machine, etc., but in Reference Example 1 In the first polishing step and the second polishing step, the same type of the polishing material slurry A is used, so that the cleaning operation of the polishing machine or the like is not required, which is advantageous in terms of work and equipment.

Though it is not shown in the table, it can be confirmed that in the second polishing step of Reference Example 1, even if the new abrasive slurry A is not replaced, the abrasive slurry A used in the first polishing step is directly used continuously. In the case, the polishing speed and the surface smoothness of the obtained substrate are hardly affected.

Claims (5)

A method for producing a composite metal oxide abrasive material, comprising the steps of: mixing a mixing step of a cerium compound with a zirconium compound, and a calcining step of calcining the mixture obtained by the mixing step; characterized in that the zirconium The amount of the SO ₃ equivalent of the sulfur compound contained in the compound is 2.0 parts by weight or less based on 100 parts by weight of the ZrO ₂ equivalent amount of the zirconium compound. The method for producing a composite metal oxide abrasive according to the first aspect of the invention, wherein the hydrazine compound in the mixing step is at least one selected from the group consisting of cesium carbonate and strontium hydroxide. The method for producing a composite metal oxide abrasive according to claim 1 or 2, wherein the zirconium compound in the mixing step is at least one selected from the group consisting of zirconium carbonate and zirconium hydroxide. The method for producing a composite metal oxide abrasive according to any one of claims 1 to 3, wherein the calcination temperature in the calcination step exceeds 800 ° C and is 1500 ° C or lower. A composite metal oxide abrasive material, wherein the SO ₃ equivalent amount of the sulfur compound contained in the composite metal oxide abrasive material is 100% by weight based on the ZrO ₂ of the zirconium compound contained in the composite metal oxide abrasive material. The serving is 1.2 parts by weight or less.