JP2008088325A - Cerium oxide-based abrasive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abrasive material suitably applied to polish glass, which is a high purity cerium oxide-based abrasive having ≥95 mass% CeO<SB>2</SB>/TREO (total rare earth oxides) and a large abrasion speed and reduced in generating abrasion cracks. <P>SOLUTION: The cerium oxide-based abrasive has 1.7-3.0 g/mL apparent density by a tap method and contains ≥95 mass% CeO<SB>2</SB>/TREO. Preferably, the fluorine content is ≤0.5 mass% and the half-value width (2θ) of the maximum peak of cerium oxide by X ray diffraction measurement is 0.10-0.50°. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a cerium oxide-based abrasive having CeO ₂ / TREO of at least 95% by mass.

  The cerium oxide-based abrasive is used for polishing glass and quartz such as a glass substrate for hard disk, a glass substrate for liquid crystal or plasma display, and a glass for CRT, and is particularly suitable for polishing glass and quartz.

As such a cerium oxide-based abrasive, a slurry in which cerium oxide particles whose apparent density measured by the tap method is 1.60 g / ml or less is dispersed in water, and an insulating film provided on a predetermined substrate A cerium oxide-based abrasive for polishing a layer is known (see Patent Document 1). Further, a cerium-based abrasive having a compression apparent density (DIN 53194) of 1.6 or 1.7 and comprising 92% CeO ₂ and 8% La ₂ O ₃ is known (see Patent Document 2).
JP-A-11-330017 JP-A-60-35075

Since the polishing material of Patent Document 1 which is the prior art is only subjected to a baking treatment of 420 ° C. or less at the time of manufacturing the polishing material, it is suitable for a polishing treatment with a relatively low polishing speed such as semiconductor polishing, but a larger polishing material. Difficult to use for glass polishing where speed is required. For this reason, when the baking treatment is performed at a higher temperature, the polishing speed increases, but a large number of coarse particles are formed, resulting in an abrasive that generates a lot of scratches. Further, since the abrasive of Patent Document 2 contains 8% La ₂ O ₃ , there is little formation of coarse particles even when fired at a certain high temperature, and the occurrence of abrasive scratches is suppressed to some extent. The polishing speed is small and it is not suitable for glass polishing.

Accordingly, the present invention is a high-purity cerium oxide-based abrasive having CeO ₂ / TREO of 95% by mass or more, which has a high polishing speed and is less likely to cause polishing scratches and is suitable for glass polishing applications. It is an issue to provide.

In order to solve the above problems, the present invention is characterized in that the apparent density by the tap method is 1.7 to 3.5 g / mL, and CeO ₂ / TREO is 95% by mass or more. The cerium oxide abrasive according to the present invention requires CeO ₂ / TREO of 95% by mass or more, preferably 99% by mass or more, more preferably 99.6% by mass or more, and further preferably 99.9% by mass or more. When it is 95% by mass or more, the polishing rate is sufficiently high, and when it is 99% by mass or more, 99.6% by mass or more, and 99.9% by mass or more, the polishing rate is further increased. And tap density needs to be 1.7-3.5 g / mL, Preferably it is 1.8-3.3 g / mL, More preferably, it is 2.0-3.0 g / mL. If it is 1.7 g / mL or more, the polishing rate is high, and if it is 1.8 g / mL or more, or 2.0 g / mL or more, the polishing rate is further increased. On the other hand, if the tap density is 3.5 g / mL or less, the occurrence of abrasive scratches is small, and if the tap density is 3.3 g / mL or less, or 3.0 g / mL or less, the occurrence of abrasive scratches is further reduced.

  The tap method apparent density of the present invention is measured by using a commercially available tap method apparent density measuring device (Tap Denser KYT-2000: manufactured by Seishin Enterprise Co., Ltd.), putting a 50.00 g sample into a 100 mL cylinder, It is a value measured by tapping 300 times at a height of 50 mm. In addition, in a normal cerium oxide-based abrasive, there is no lump that does not pass through a sieve having an aperture of 0.5 mm, and therefore pretreatment with a sieve having an aperture of 0.5 mm is not performed.

  And it is preferable that the cerium oxide type abrasive | polishing material of this invention is 0.5 mass% or less of fluorine. Fluorine affects the phenomenon of polishing particles adhering to the surface to be polished. If the amount is 0.5% by mass or less, the amount of abrasive particles adhering to the surface to be polished is small, and 0.1% by mass or less. If it exists, adhesion will decrease further and it is more preferable.

  Moreover, it is preferable that the half width (2 (theta)) of the maximum peak of cerium oxide in a cerium oxide type abrasive | polishing material of this invention is 0.10 to 0.50 degree. If the half-value width (2θ) of the maximum peak is 0.10 ° or more, the occurrence of abrasive scratches is small, and if it is 0.15 ° or more or 0.20 ° or more, the occurrence of abrasive scratches is even less. If the half width (2θ) of the maximum peak is 0.50 ° or less, the polishing rate is high, and if it is 0.45 ° or less or 0.40 ° or less, the polishing rate is further increased. Note that the X-ray diffraction measurement of the present invention is performed in a range of 20 to 40 ° in 2θ or a wider range based on the CuKα1 line. The maximum peak of cerium oxide appears at about 28.6 ° at 2θ.

  Further, in the cerium oxide-based abrasive of the present invention, the content of particles having a particle size of 10 μm or more is preferably 1000 ppm by mass or less. More preferably, it is 300 mass ppm or less. It is desirable that the content of coarse particles is small from the viewpoint of less generation of abrasive scratches, and the content of particles having a particle size of 10 μm or more is preferably 1000 ppm by mass or less, more preferably 300 ppm by mass or less, and even more preferably 100 masses. ppm or less.

Further, the cerium oxide-based abrasive of the present invention preferably has a BET specific surface area of 1 to 10 m ² / g. If the BET method specific surface area is 10.0 m ² / g or less, the polishing rate is increased. If it is 6.0 m ² / g or less, the polishing speed is higher, and if it is 5.5 m ² / g or less, the polishing speed is further increased. On the other hand, if it is 1 m ² / g or more, the generation of abrasive scratches is reduced, if it is 1.5 m ² / g or more, the generation of abrasive scratches is less, and if it is 2.0 m ² / g or more, further polishing scratches are generated. The occurrence of is reduced.

The cerium oxide-based abrasive of the present invention preferably has a 50% diameter (D ₅₀ ) of 1.0 to 3.5 μm in a volume-based integrated fraction of laser diffraction / scattering particle size distribution measurement. _Further, more preferably _{D 50} is 1.5-3.0, more preferably 1.8～2.8Myuemu. If D ₅₀ is 1.0 μm or more, the polishing speed is high, if it is 1.5 μm or more, the polishing speed is higher, and if it is 1.8 μm or more, the polishing speed is further increased. On the other hand, if D ₅₀ is 3.5 μm or less, the generation of abrasive scratches is small, and if it is 3.0 μm or less, the generation of abrasive scratches is less, and if it is 2.8 μm or less, the generation of abrasive scratches is further reduced.

The above-described cerium oxide-based abrasive of the present invention can be produced as follows. First, as the raw material, cerium carbonate, cerium monooxycarbonate, cerium hydroxide carbonate, or a mixture of two or more thereof can be used. These raw materials may be used as they are, but may be dried from 130 to 250 ° C. in a moisture-containing state and the ignition loss adjusted to 5 to 25% by mass (high purity product). (If CeO ₂ / TREO ≧ 95 mass%), this drying treatment often results in cerium oxide). In any of the above raw materials, after the raw material itself is CeO ₂ / TREO ≧ 95% by mass, the fine particles are pulverized to reduce coarse particles, and then the fine particles are removed by wet classification. After solid-liquid separation, it can be manufactured by roasting and classifying the roasted product to remove coarse particles.

  The pulverization treatment is preferably wet pulverization, and pulverization by a wet medium pulverizer is particularly preferable. As a medium for use in a wet medium pulverizer, a spherical product having a diameter of 0.4 to 10 mm or a shape other than a sphere having the same volume as a sphere having a diameter of 0.4 to 10 mm (for example, a cylindrical product) is preferable. The slurry used for wet medium pulverization is preferably a mixture of raw material: water at a ratio (mass) of 1: 9 to 2: 1, and a mixture of 1: 4 to 3: 2 ratio (mass). Further preferred. According to the pulverization treatment by such a wet medium pulverizer, it is advantageous in terms of cost with high pulverization efficiency.

The pulverized raw material preferably has a 90% diameter (D ₉₀ ) in a volume-based integrated fraction of laser diffraction / scattering particle size distribution measurement of 1.5 to 10 μm, and more preferably 2 to 5 μm. If D ₉₀ of the pulverized raw material is 1.5 μm or more, loss in the next fine particle removal step can be suppressed, and if it is 2 μm or more, it is even better. On the other hand, if the D _{90 of} the pulverized raw material is 10 μm or less, residual coarse particles due to insufficient pulverization can be prevented, and if it is 5 μm or less, it is even better.

Further, the pulverized raw material preferably has a 10% diameter (D ₁₀ ) in a volume-based integrated fraction of laser diffraction / scattering particle size distribution measurement of 0.1 μm or more and less than 0.4 μm. More preferably, it is 0.2 μm or more and 0.35 μm or less. If pulverized treated D ₁₀ of the raw material is 0.1μm or more, can suppress the loss in the subsequent particle removal step, more loss is reduced if the 0.2μm or more. Also,. Milling treated D ₁₀ of raw material, it is less than 0.4 .mu.m, prevents retention of coarse particles by crushing shortage can be suppressed more residual if 0.35μm or less.

  The pulverized raw material is subjected to a fine particle removal process. The removal process of the fine particles can be performed by wet classification. As one of the methods, a wet classifier can be used. For example, if a wet classifier such as a wet cyclone is used, fine particles can be easily removed.

  As another method, sedimentation separation can be used. The pulverized raw material slurry is diluted as necessary, and after uniform mixing, it is allowed to settle and settle, and the fine suspension is removed by extracting the diluted suspension above the sediment cake layer. Since the removal rate of fine particles is low in a single sedimentation process, the sedimented cake after extracting the diluted suspension is slurried (homogeneously mixed), allowed to settle again and sedimented, and above the sedimented cake layer. It is preferred to extract the dilute suspension. The standing / sedimentation and extraction of the diluted suspension are preferably performed 2 to 5 times including the beginning, and more preferably 2 to 3 times. Although the removal of the fine particles progresses as the process is performed many times, a very long processing time is required.

  The sedimentation time of the sedimentation separation determines the critical Stokes diameter, and the particles having the critical Stokes diameter on the upper liquid surface of the fine particle removal step slurry are settled (for example, when a diluted suspension outlet is provided, The time required to settle the distance from the upper liquid surface to the diluted suspension outlet can also be determined by calculating from the Stokes equation. According to the method of determining the sedimentation time from the limit Stokes diameter and removing the fine particles, particles larger than the limit Stokes diameter do not remain in the dilute suspension, but all the particles having a diameter less than the limit Stokes diameter are all present. It is not included in the dilute suspension. Therefore, as described above, it can be said that a method in which the stationary / sedimentation and the extraction of the diluted suspension are performed a plurality of times is desirable. The limit Stokes diameter is preferably 0.2 to 1.0 μm, and more preferably 0.3 to 0.8 μm. Although this method can remove only particles having a limit Stokes diameter or less, it is more laborious than a wet classifier.

The raw material after the fine particle removal treatment preferably has a 10% diameter (D ₁₀ ) in a volume-based integrated fraction of laser diffraction / scattering particle size distribution measurement of 0.4 to 1.2 μm, preferably 0.5 to 1.0 μm. Is more preferable. If the particle size is 0.4 μm or more, the number of fine particles is small, and the sintering of the fine particles proceeds too rapidly when roasted, thereby suppressing the generation of coarse particles that cause abrasive flaws. The Further, if only D ₁₀ of the material is below 1.2 [mu] m, or not performed milling, lightly and milling, although particulate removal is also possible not to perform, there are many coarse particles are not grinding, roasting After firing, it remains as coarse particles and tends to cause abrasive scratches.

  The raw material from which the fine particles have been removed is preferably filtered with a filter such as a filter press, dried and crushed. It is also possible to spray dry without filtering. When pulverization is performed, the pulverization should be performed so as not to generate a large amount of fine particles.

  The roasting treatment is preferably 650 to 1200 ° C, more preferably 700 to 1150 ° C, and further preferably 750 to 1100 ° C. If roasting is performed at 650 ° C. or higher, an abrasive with a high polishing rate can be produced. At 700 ° C. or higher and 750 ° C. or higher, an abrasive with a higher polishing rate is easily obtained. If it is 1200 degrees C or less, the abrasive | polishing material in which generation | occurrence | production of the abrasion damage was suppressed can be manufactured, and if it is 1150 degrees C or less and 1100 degrees C or less, the abrasive material in which generation | occurrence | production of the abrasion damage was suppressed more easily will be obtained.

  The roasted product is preferably pulverized before classification. Using a hammer-type impact pulverizer is a simple method, and this method is preferable because coarse particles can be reduced without excessive atomization.

The classification treatment can be performed in order to reduce coarse particles having a particle size of 10 μm or more. The classification treatment is simple and preferably performed using various dry classification apparatuses. In the cerium oxide-based abrasive of the present invention, when the raw material is pulverized to remove fine particles and roasted, coarse particles can be sufficiently reduced by classification, and the raw material has a high purity of CeO ₂ / TREO of 95% by mass or more. In addition, it is possible to produce an abrasive with suppressed generation of abrasive scratches. However, when the raw material is pulverized and roasted without removing fine particles, the raw material has a high purity of CeO ₂ / TREO of 95% by mass or more, so that a large amount of coarse particles are generated by the roasting, which is classified. However, care must be taken because coarse particles having a particle size of 10 μm or more can be removed only to some extent, and the resulting abrasive may generate many abrasive scratches. In addition, when not performing the removal processing of the fine particles for the above-mentioned pulverized raw material, even if a large number of coarse particles are generated by the roasting process, the pulverization and classification process of the roasted product is extremely strengthened, It is possible to reduce coarse particles in the abrasive to some extent. However, the amount of fine particles in the polishing material becomes very large, the apparent density of the tap method decreases, and the polishing speed becomes very low.

According to the present invention, it is a high-purity cerium oxide-based abrasive having a CeO ₂ / TREO of 95% by mass or more, having a high polishing rate, and generating less scratches, and suitable for glass polishing applications. It becomes a cerium-based abrasive.

  Hereinafter, although the best mode in the present invention is described based on an example, the present invention is not limited to the following example.

  In this embodiment, each polishing material (Tables 1 to 3) of Examples 1 to 24 and Comparative Examples 1 to 12 in which raw materials and manufacturing conditions were changed was produced, and the polishing characteristics were examined.

(1) A cerium oxide-based abrasive whose presence or absence of the raw material fine particle removal treatment and the roasting temperature was changed: The abrasive here was produced according to the following production conditions. A bead mill using a zirconia ball having a diameter of 1.2 mm with a slurry prepared by mixing cerium carbonate with 45% by mass of TREO and CeO ₂ /TREO≧99.9% by mass of raw material: water = 1: 2 (mass ratio). Passed three times.

  The pulverized raw material was subjected to sedimentation separation with a limit Stokes diameter of 0.5 μm three times (Examples 1 to 11, Comparative Examples 6 and 7). Moreover, what does not perform the fine particle removal process by sedimentation separation was also prepared for the comparison (Comparative Examples 1-5).

  After that, each raw material was filtered with a filter press and dried at 120 ° C. for 24 hours. After drying, crushing treatment was performed using an atomizer (Fuji Paudal Co., Ltd.).

The crushed raw material was subjected to a roasting process for 12 hours at each roasting temperature shown in Table 1.

After the roasting treatment, pulverization processing (hereinafter, all the same conditions) is performed by an atomizer (manufactured by Fuji Powdal Co., Ltd.) equipped with a screen having a mesh opening of 2 mm, and the turbo classifier (Nisshin Engineering Co., Ltd.). The product was classified at a classification point of 8 μm. Table 1 shows the production conditions of each abrasive for (1).

(2) A cerium oxide-based abrasive with different CeO ₂ / TREO: The abrasive here was produced under the following production conditions. The abrasives of Examples 12 to 14 and Comparative Example 8 were prepared using the raw materials having the respective CeO ₂ / TREO values shown in Table 2 under the same conditions as in Example 6 above. The polishing materials of Examples 15 to 17 and Comparative Example 9 were roasted at the temperatures shown in Table 2 using raw materials having different CeO ₂ / TREO values shown in Table 2. Other manufacturing conditions were the same as those in Example 6 above.

(3) Cerium oxide-based abrasives with different fine particle removal treatment conditions: The abrasives here were produced under the following production conditions. The abrasives of Examples 18 to 20 are based on the method of determining the settling time from the limit Stokes diameter and removing the fine particles. In Example 18, the settling separation determined to be the limit Stokes diameter of 0.3 μm was performed three times. . In Example 19, sedimentation separation with a limit Stokes diameter of 0.5 μm was performed once. In Example 20, sedimentation separation with a limiting Stokes diameter of 0.8 μm was performed once. Moreover, about the abrasive of Example 21, the fine particle removal process by wet cyclone was performed, and a classification point was 0.5 micrometer with the wet cyclone apparatus (Spur clone TR-30 type (made by Murata Industrial Co., Ltd.)). Carried out. Other manufacturing conditions were the same as those in Example 6 (see Table 2).

(4) A cerium oxide-based abrasive in which the form of the raw material was changed: The abrasive here was produced under the following production conditions. In the abrasive of Example 22, after adding １ ／ of pure water to the cerium carbonate used in (1) above, it was dried in a dryer at 200 ° C. for 72 hours to obtain cerium oxide and The raw material was used. In the polishing material of Example 23, the cerium carbonate used in (1) above was placed in a tank equipped with a stirrer at a ratio of cerium carbonate: pure water = 1: 2 (mass), and steam was blown to rise to 90 ° C. After heating, the temperature was kept at 90 ° C. for 12 hours to obtain a slurry of cerium monooxycarbonate, which was allowed to cool to 30 ° C. as a raw material (since it was already a slurry, it was directly used for pulverization and pulverization). In the abrasive of Example 24, the cerium carbonate used in (1) above was placed in a tank equipped with a stirrer at a ratio of cerium carbonate: 20 g / L aqueous ammonium hydrogen carbonate = 1: 2 (mass), and steam was blown into it. The temperature was raised to 90 ° C. and maintained at 90 ° C. for 12 hours to obtain a cerium hydroxide carbonate slurry. After cooling to 30 ° C., filtration was performed to obtain cerium hydroxide carbonate as a raw material. Other manufacturing conditions were the same as those in Example 6 (see Table 2).

(5) A cerium oxide-based abrasive produced by a method similar to the example of Patent Document 1 (Japanese Patent Laid-Open No. 11-330017): For comparison, an abrasive was produced under the following production conditions. First, a bead mill using a zirconia ball having a diameter of 1.2 mm using a slurry prepared by mixing cerium carbonate having 45% by mass of TREO and CeO2 / TREO ≧ 99.9% by mass as a raw material and raw material: water = 1: 9 (mass ratio). The powder was pulverized by passing it through 3 times. While the slurry was stirred, 35% hydrogen peroxide was added to the pulverized raw material over a period of 1 hour, and 584 g per kg of cerium carbonate was added over 1 hour. After warming, it was kept at 90 ° C. for 1 hour. And it filtered and performed the drying process for 120 hours and 120 degreeC, and produced the cerium oxide particle (The tap density (TD) of this cerium oxide particle was 1.46 g / mL).

  The abrasive of Comparative Example 10 uses cerium oxide particles obtained by the above method, and a slurry prepared by mixing cerium oxide particles: pure water: polyacrylic acid ammonium salt (mass ratio) = 10: 100: 1 has a diameter of 0.00. A cerium oxide slurry that was passed through a bead mill using 4 mm zirconia balls three times and was subjected to a dispersion treatment (the abrasive of this Comparative Example 10 was in a slurry state, so the tap density (TD) could not be measured). . Further, the abrasive of Comparative Example 11 was crushed by an atomizer (Fuji Powdal Co., Ltd.) using the cerium oxide particles obtained by the above method, and a turbo classifier (Nisshin Engineering Co., Ltd.). Then, classification was carried out to prepare an abrasive (the tap density (TD) of this abrasive was 1.37 g / mL). The abrasive of Comparative Example 12 was subjected to the same conditions as in Comparative Example 3 from raw material formation to roasting, and then the roasted product was pulverized five times with an atomizer, and the turbo classifier was set at a classification point of 5 μm. Then, a classification process was performed.

About each abrasive obtained under the above manufacturing conditions, its composition, fluorine concentration, content of coarse particles having a particle size of 10 μm or more, tap density, X-ray diffraction measurement, specific surface area, laser diffraction / scattering method particle size distribution Measurement was carried out for a 50% diameter (D ₅₀ ) in the volume-based integrated fraction of the measurement. Each measurement condition is as follows.

Measurement of composition: Analysis of the TREO concentration was carried out by first dissolving the abrasive and adding oxalic acid, and then separating the resulting precipitate by filtration and firing to obtain a TREO oxide. Then, the TREO sample was subjected to mass measurement, and the content of CeO ₂ , La ₂ O ₃ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ (CeO ₂ / TREO, La ₂ O ₃ / (TREO, Pr ₆ O ₁₁ / TREO, Nd ₂ O ₃ / TREO, Sm ₂ O ₃ / TREO). Here, La ₂ O ₃ / TREO, Pr ₆ O ₁₁ / TREO, Nd ₂ O ₃ / TREO, Sm ₂ O ₃ / TREO were determined by ICP-AES method after acid dissolution of the TREO sample. Then, the CeO ₂ does not perform the direct measurement, using the values obtained _{above, 100 - {(La 2 O} 3 / TREO) + (Pr 6 O 11 / TREO) + (Nd 2 O 3 / TREO ) + (Sm ₂ O ₃ / TREO)}.

Fluorine concentration: As a method for quantifying the fluorine component, the sample was melted with alkali, extracted with warm water, and measured by the fluorine ion electrode method. Moreover, about Fe, Ca, and Ba, after making it melt | dissolve with an acid, it measured by ICP-AES method.

Measurement of the content of coarse particles having a particle size of 10 μm or more: The measurement of the content of coarse particles is carried out by weighing 200 g of the produced cerium-based abrasive (in the case of slurry, a slurry corresponding to a solid content of 200 g), putting it in a measurement container, and adding 0.1 A sodium hexametaphosphate aqueous solution was added to the upper marked line of the measurement vessel and mixed well. Next, it was allowed to stand for a specified time and allowed to settle. After the designated time had elapsed, the slurry between the upper marked line and the lower marked line was extracted. After extracting the slurry, add a new 0.1% sodium hexametaphosphate aqueous solution to the upper marked line of the measuring container, mix well, let it settle for a specified time, and then set the upper marked as before. Slurry was extracted from the line to the bottom marked line. Such a series of operations (injection of sodium hexametaphosphate aqueous solution, mixing, standing and settling, extraction of slurry) were repeated. This series of operations was further repeated 6 times for a total of 8 times, and finally, the particles remaining below the lower marked line of the measurement container were sufficiently dried at a temperature of 105 ° C. The mass A (g) of the dry residue thus obtained was measured with a precision balance. Then, the content S (mass ppm) of coarse particles having a Stokes diameter of 10 μm or more was calculated using the calculation formula S = (A / 200) × 1000000. The specified time (stationary / sedimentation time) is the time required for particles with a Stokes diameter of 10 μm at the position of the upper marked line (the upper surface of the slurry) to settle to the lower marked line. Is divided by the settling velocity calculated from the Stokes equation. When the above series of operations is performed only once, many particles having a Stokes diameter of less than 10 μm are mixed in the following part of the lower marked line. Therefore, by repeating this series of operations many times, the Stokes diameter is less than 10 μm. It is necessary to reduce the amount of mixed particles to a negligible level. The above series of operations was carried out using a 0.1% sodium hexametaphosphate aqueous solution having a liquid temperature of about 25 ° C. in an atmosphere at room temperature of about 25 ° C.

Tap method apparent density: In this tap method apparent density (TD) measurement, 50.00 g of a sample was weighed, and the sample was put into a 10 mL plastic cylinder, and Tap Denser KYT-2000 (manufactured by Seishin Enterprise Co., Ltd.) The cylinder was set to, and after tapping 300 times at a tap height of 50 mm, the volume of the sample (V mL) was measured and calculated from TD (g / mL) = 50 ÷ V.

X-ray diffraction measurement: Using an X-ray analyzer (manufactured by Mac Science Co., Ltd .: MXP18), with a Cu target, the tube voltage is 40 kV, the tube current is 150 mA, and the measurement range is 20 to 40 ° in 2θ, It can be measured with a sampling width of 0.02 ° and a scanning speed of 2 ° / min. The obtained diffracted X-rays are separated into those based on the CuKα ₁ line and those based on the CuKα ₂ line, and the FWHM of the maximum peak near 28.6 ° at 2θ for the diffracted X-ray based on the CuKα ₁ line. Was measured.

Specific surface area measurement: Based on the BET method, compliant with “6.2 Flow method (3.5) single point method” in JIS R 1626-1996 (Method for measuring specific surface area of fine ceramic powder by gas adsorption BET method) Then, the specific surface area of the abrasive was measured. At that time, a mixed gas of helium as a carrier gas and nitrogen as an adsorbate gas was used.

50% diameter (D ₅₀ ) measurement in volume-based cumulative fraction of laser diffraction / scattering method particle size distribution measurement: Laser diffraction / scattering method particle size distribution measuring device (manufactured by Horiba, Ltd .: LA-920) is used. Then, by measuring the particle size distribution of each abrasive raw material and each cerium-based abrasive, the average particle size (D ₅₀ : particle size <median diameter> at a cumulative mass of 50% by mass from the small particle size side) is obtained. It was.

  The physical property data of each abrasive is shown in Tables 4-6.

  And the grinding | polishing characteristic about each abrasive material was evaluated. As polishing characteristics, polishing speed, polishing scratches, and surface properties of the surface to be polished (surface roughness Ra, microwaviness) were investigated. Below, the measuring method of each characteristic evaluation is demonstrated.

Polishing speed: A polishing tester (HSP-2I type, manufactured by Taito Seiki Co., Ltd.) was prepared as a polishing machine. This polishing tester polishes the polishing target surface with a polishing pad while supplying a slurry-like polishing material to the polishing target surface. The abrasive grain concentration of the abrasive slurry was 100 g / L (dispersion medium was water only). In this polishing test, a slurry-like abrasive was supplied at a rate of 5 liters / minute, and the abrasive was recycled. The polishing object was 65 mmφ flat panel glass. A polishing pad made of polyurethane was used. The polishing pad pressure on the polishing surface was 9.8 kPa (100 g / cm ² ), the rotation speed of the polishing tester was set at 100 min ⁻¹ (rpm), and polishing was performed for a predetermined time. And after performing the polishing process for the specific time, it washed with water, dried, measured the glass weight before and behind polishing, calculated | required the reduction | decrease amount of the glass weight by polishing, and calculated | required the polishing value based on this value. In this polishing evaluation, the polishing rate was evaluated using this polishing value. In addition, as shown in Table 7, the evaluation value of this polishing rate was calculated based on the polishing value obtained with the cerium-based polishing material of Comparative Example 3 as a reference (100). The measurement object of the abrasive scratches, arithmetic average microwaviness, and arithmetic average surface roughness (Ra) described later is glass that has been subjected to a polishing treatment for a specific time, then washed with water and dried.

Abrasion scratches: Abrasion scratches are evaluated by observing the polished glass surface with a reflection method using a 300,000 lux halogen lamp as the light source, scoring the number of large and fine scratches, and then deducting the score from 100 points. The method was performed. In this scratch evaluation, the polishing accuracy required for finish polishing of a glass substrate for a hard disk (HD) or LCD was used as a criterion. Specifically, in Tables 7 to 9, “◎” is 98 points or more (very suitable for finishing polishing of glass substrates for HD and LCD), and “◯” is 95 points less than 98 points. That it is above (suitable for finishing polishing of HD / LCD glass substrates), and “△” is less than 95 points and 90 points or more (can be used for finishing polishing of HD / LCD glass substrates). "X" indicates that it is less than 90 points (cannot be used for finish polishing of glass substrates for HD and LCD).

Arithmetic average surface roughness Ra: This arithmetic average surface roughness is determined by using DFM (dynamic force mode) with a probe microscope SPA-400 (manufactured by SSI Nanotechnology Co., Ltd.). The 10 μm × 10 μm range was measured to obtain the arithmetic average surface roughness (Ra: nm) value.

Arithmetic average micro-waviness: The arithmetic average micro-waviness uses a three-dimensional surface structure analysis microscope (New View 200 manufactured by Zygo) to scan the polishing surface with white light at a measurement wavelength of 0.2 to 1.4 mm. Measured.

  The evaluation results of the polishing characteristics are shown in Tables 7-9.

  From the evaluation results of the polishing characteristics shown in Tables 7 to 9, when the glass was polished with the cerium oxide-based abrasive of this example, it was found that the polishing characteristics were high and the polishing characteristics were small. found.

Claims (6)

A cerium oxide-based abrasive having an apparent density by a tap method of 1.7 to 3.5 g / mL and CeO ₂ / TREO of 95% by mass or more. The cerium oxide-based abrasive according to claim 1, wherein the fluorine is 0.5 mass% or less. The cerium oxide-based abrasive according to claim 1 or 2, wherein a half-value width (2θ) of the maximum peak of cerium oxide in X-ray diffraction measurement is 0.10 to 0.50 °. The cerium oxide-based abrasive according to any one of claims 1 to 3, wherein the content of particles having a particle size of 10 µm or more is 1000 ppm by mass or less. The cerium oxide-based abrasive according to claim 4, wherein the content of particles having a particle size of 10 µm or more is 300 ppm by mass or less. The BET method specific surface area is 1-10 m < ² > / g, The cerium oxide type abrasive | polishing material of any one of Claims 1-5.