JP4131870B2 - Abrasive particle quality evaluation method, glass polishing method and abrasive composition for polishing glass - Google Patents

Description

  The present invention relates to a polishing material for glass polishing, and more particularly, is suitable for finish polishing of various glass materials, and in particular, maintains a high polishing rate of a polishing material for glass polishing mainly containing a rare earth oxide containing cerium oxide. In addition, the present invention relates to a polishing material for glass polishing in which scratches, particularly latent scratches, generated in the glass to be polished are reduced to an unprecedented level and a method for evaluating the quality.

In recent years, glass materials have been used for various applications. Not only glass materials for optical applications such as optical lenses, but also glass substrates for liquid crystals, recording disks such as magnetic disks and optical disks, glass substrates for LSI photomasks, etc. These are also used in the field of manufacturing electronic circuits, and all of them basically require surface polishing with high accuracy.
Conventionally, as a polishing material used for surface polishing of these glass substrates, a polishing material mainly containing a rare earth oxide, particularly cerium oxide, has been used. This is because cerium oxide as an abrasive grain is advantageous in that the polishing efficiency of glass is several times better than that of zirconium oxide or silicon dioxide. In recent years, in response to the rapid growth of so-called digital home appliances, the display screen of an FPD such as a liquid crystal display, which is a key device, is becoming increasingly larger, or like a portable terminal. Such a small panel is also required to display a color image and the like clearly, and a higher-definition panel is required.
In addition, when an HDD such as a magnetic disk is incorporated in a DVD recorder, for example, a TV program or the like is compatible with high-density recording of about 100 to 200 gigabytes for recording TV programs and the like for a long time. As for the surface accuracy, it is required that the surface be polished with higher accuracy to be highly smooth. Also from this point, the polishing ability of the abrasive is required to be higher quality.
In addition, as will be described later, it is general that an abrasive mainly composed of cerium oxide for glass polishing contains a fluorine component for the reason that the polishing performance is improved.
In these abrasives mainly composed of cerium oxide, for example, the particle size of the abrasive particles is the polishing rate, the average roughness (surface smoothness), and the occurrence of scratches and scratches (scratches and latent scratches). It is known to affect polishing performance.
For example, Japanese Patent Application Laid-Open No. 2000-273443 describes that the number of latent scratches can be reduced by setting specific coarse particles (6 μm or more) to 300 ppm or less. Further, in JP-A No. 2001-72962, in the case of sol particles of abrasive grains substantially composed of pure cerium, the average secondary particle diameter (median diameter) that is an aggregate of the primary particles is reduced (0.1 to 0.1). It is disclosed that the surface roughness can be reduced while maintaining the polishing rate.
Furthermore, JP-A No. 2003-261861 proposes an index for evaluating the aggregation state, focusing on the fact that the dry particles having a low degree of aggregation have good dispersibility. Yes. That is, for the abrasive particles, the particle diameter (D _N ) of the abrasive particles measured by the BET method (corresponding to the particle size of the primary particles) and the particle diameter of the abrasive particles measured by the air permeation method ( D _A ) (approximate to the particle size of the aggregated particles), the abrasive particles satisfying the relationship of 1 <= D _A / D _N <= 10 have little aggregation and dispersibility in an aqueous medium. It is said that stable polishing characteristics can be obtained.
However, among the methods for evaluating the particle size and agglomeration characteristics of the abrasive particles, in Japanese Patent Application Laid-Open No. 2000-273443, whether the target coarse particles are the particle sizes of primary particles or aggregate particles. No distinction is made, and in JP-A No. 2001-72962, the particle diameter (secondary particle diameter) of the aggregate particles is defined. The degree to which the particles can be redispersed into primary particles is not studied. From a practical point of view, even if the abrasive particles contain some aggregate particles in a dry state, if the aggregate can be easily dispersed (or crushed) in an aqueous medium, There is no point in trying to remove it more than necessary. From the economic rationality, it is preferable to obtain the maximum effect by the minimum necessary processing.
Furthermore, the index indicating aggregation described in Japanese Patent Application Laid-Open No. 2003-261861 is merely a measure of the degree of aggregation of the abrasive particles in a dry state (magnification size). Therefore, it does not directly indicate the ease of dispersion or the difficulty of dispersion (dispersibility) when the particles are dispersed in an aqueous medium.
Basically, the abrasive for polishing glass is an abrasive composition (also referred to as “abrasive slurry”) in which abrasive particles (abrasive grains) are dispersed in an aqueous medium at the time of use. In that case, not only the improvement of the productivity of the polishing process, that is, the high polishing rate and the maintenance and sustainability of the polishing rate, but also the higher level of both the productivity and the quality of maintaining the high quality level of the polished surface is required. ing. However, the improvement of the polishing rate and the maintenance of high quality are rather contradictory requests and are incompatible. For example, if the amount of coarse abrasive grains is increased, the polishing rate will be increased, but it will be readily understood that scratches such as scratches on the polished surface tend to increase.
In the past, fine scratches on the polished surface, which are particularly important for the quality of the polished surface, have been conventionally observed (scratches observed by observing the dried polished surface with a microscope under visible light). It was sufficient to evaluate the number of scratches on the polished surface. However, as described above, the level of quality requirements for liquid crystal glass substrates, hard disk glass substrates, etc. has hitherto been high in response to the progress of the development and development of the electronics industry, such as liquid crystal monitors. Compared to, it is becoming much higher than expected.
With the demand for higher quality of the polished surface, it is natural that the evaluation method for fine scratches on the polished surface is free from obvious scratches, and the number of latent scratches is also required to be strictly evaluated. is what happened. Here, the term “latent scratch” refers to a fine scratch that is difficult to find with the above-described evaluation method for stigmatism, by polishing the polished surface with a dilute hydrofluoric acid solution and clarifying the scratch on the polished surface after drying. It is a scratch that is recognized only when the surface is observed with a microscope (for example, Olympus, system metal microscope, BHT type, etc.). Thus, there is now a demand for a more rigorous polished surface quality evaluation method that evaluates by the number of latent scratches.
For conventional abrasives (abrasive particles) that are dry powders mainly composed of cerium oxide, the coarse particle size and the amount of aggregate particles are in the desired range as proposed in the above-mentioned published patent publication. However, in terms of achieving a high quality polished surface considering the number of latent scratches while maintaining and maintaining a high polishing rate in glass polishing, it was not always satisfactory.
An object of the present invention is to provide a glass polishing abrasive, particularly a glass polishing abrasive mainly composed of a rare earth oxide containing cerium oxide. It is to provide a polishing material for glass polishing that is reduced to an unprecedented level, and to provide a quality evaluation method for evaluating the quality of the abrasive particles, particularly with respect to latent scratches, with respect to powder.

According to the present invention, the following inventions are provided.
[1] A method for evaluating the dispersibility of abrasive particles for polishing glass in an aqueous medium, comprising preparing an aqueous medium dispersion of abrasive particles obtained by adding abrasive particles to be measured to an aqueous medium. , irradiated with ultrasonic waves in the dispersion liquid, the formula (1), for the presence of the ultrasonic particular particle size before irradiation alpha _{0 ([mu]} m) or more particles, said after ultrasonic irradiation alpha ₀ Quality related to dispersibility of abrasive particles for glass polishing in an aqueous medium, characterized by measuring the proportion of particles (μm) or more disappearing by the action of ultrasonic irradiation (defined as dispersion ratio (ξ)) Evaluation methods.
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
[2] A method of polishing glass with abrasive particles,
An aqueous medium dispersion of abrasive particles obtained by adding abrasive particles to be measured to an aqueous medium is prepared, and the dispersion is irradiated with ultrasonic waves. The ultrasonic irradiation represented by the formula (1) It is defined as the ratio (dispersion rate (ξ)) that disappears due to the ultrasonic irradiation effect of the particles of α ₀ (μm) or more after the ultrasonic irradiation with respect to the existing amount of particles of the specific particle diameter α ₀ (μm) or more. )
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
Adjusting, selecting or discriminating abrasive particles having a dispersion ratio ξ measured by the method of formula (1) equal to or higher than a specific value ξ ₀ (%);
A glass polishing method comprising performing glass polishing with the specified abrasive particles.
[3] The glass polishing method according to [2], wherein ξ ₀ is 30 (%).
[4] In an abrasive composition for polishing glass comprising abrasive particles,
The abrasive particles are
An aqueous medium dispersion of abrasive particles obtained by adding the abrasive particles to an aqueous medium is irradiated with ultrasonic waves, and the specific particle diameter α ₀ (μm) before the ultrasonic irradiation represented by the formula (1) The ratio (defined as the dispersion ratio (ξ)) of the above-mentioned particle abundance disappearing due to the ultrasonic irradiation action of the particles of α ₀ (μm) or more after ultrasonic irradiation is measured.
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
Abrasive composition for glass polishing, wherein abrasive particles having a dispersion ratio ξ measured by the method of formula (1) of a specific value ξ ₀ (%) or more are dispersed in an aqueous medium .
[5] The abrasive composition for polishing glass according to [4], wherein ξ ₀ is 30 (%).
[6] In the abrasive particles mainly composed of a rare earth oxide containing cerium oxide, the amount of SO ₄ equivalent metal sulfate in the abrasive is 0.070 (mol / Kg) or less, and The abrasive particles are
An aqueous medium dispersion of abrasive particles obtained by adding the abrasive particles to an aqueous medium is irradiated with ultrasonic waves, and the specific particle diameter α ₀ (μm) before the ultrasonic irradiation represented by the formula (1) The ratio (defined as the dispersion ratio (ξ)) of the above-mentioned particle abundance disappearing due to the ultrasonic irradiation action of the particles of α ₀ (μm) or more after ultrasonic irradiation is measured.
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
An abrasive particle for polishing highly dispersible glass, wherein the dispersion particle ξ measured by the method of formula (1) is an abrasive particle having a specific value ξ ₀ (%) or more.
[7] The abrasive particles for polishing highly dispersible glass according to [6], wherein ξ ₀ is 30 (5%).
[8] The abrasive particle according to [6] or [7], which contains a fluorine compound.
[9] An abrasive composition for polishing glass comprising at least an aqueous medium and the abrasive particles according to any one of [6] to [8].
[10] A glass polishing method using the glass polishing abrasive composition according to [9].

Hereinafter, the best mode for carrying out the present invention will be described in detail.
(Evaluation of coarse particle amount and aggregation strength in aqueous medium)
In the present invention, the quality evaluation regarding the dispersibility of abrasive particles for polishing glass in an aqueous medium is as follows. The intensity of the aggregation of abrasive particles by ultrasonic irradiation, and the coarse particles comprising aggregates are as follows. This is done by evaluating the amount.
That is, an abrasive aqueous medium dispersion in which abrasive particles to be measured are added to an aqueous medium is prepared, and the aqueous medium dispersion is irradiated with ultrasonic waves, and the ultrasonic wave represented by the formula (1). Ratio of disappearance due to ultrasonic irradiation action of particles of α ₀ (μm) or more after ultrasonic irradiation with respect to the abundance of particles having a specific particle diameter α ₀ (μm) or more before irradiation (defined as dispersion rate (ξ)) )).
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
The technical significance of the above formula (1) is as follows. That is, the abrasive particles mainly composed of a rare earth oxide containing cerium oxide are primary particles thereof (the primary particles referred to here are not single crystals but are substantially composed of polycrystalline particles). It is generally known that the same)) constitutes aggregated aggregate particles. Further, although the abrasive particles have a particle size distribution even in the composition in the aqueous medium, as a result of detailed studies, the present inventors have made scratches (scratches and latent defects) on the polished surface. As a factor that greatly affects (scratches), the extreme of coarse particles (for example, particles having a particle diameter α ₀ = 10 μm or more) having a particle diameter in the abrasive particles in the aqueous medium having a certain value (α ₀ ) or more. It has been found that the abundance (several ppm to several hundred ppm) is an important factor.
Usually, the average particle size of abrasive particles for glass polishing is generally about 0.3 to 3 μm, and such particles with a particle size of 10 μm or more, particularly about 10 to 50 μm, are coarse particles (coarse particles). The abundance of is very small.
The value of α ₀ is generally a value experimentally determined depending on the type of abrasive particles used, the average particle size, the target polishing quality, and the like. In the case of particles, sufficient results can be obtained if α ₀ = 10 μm is set, as will be shown in Examples below.
However, it should be noted here that the coarse particles may mean that the aggregate particles obtained by aggregating the primary particles may be coarse in addition to the case where the primary particles themselves are coarse. And when the present inventors examined in more detail, in the aqueous | water-based medium among what is forming the coarse aggregate particle in a powder state, it decomposes | disassembles easily to the primary particle which is a constituent particle. The present inventors have found that the agglomeration is strong, and even in an aqueous medium, the state of the coarse aggregate particles can be substantially maintained and the particles are not easily dispersed in the primary particles. That is, the important point is not the particle size or abundance of the aggregate particles of the coarse particles, but the degree of aggregation (the degree of ease of loosening of the aggregates into primary particles in an aqueous medium, It was also found that the degree of difficulty in unraveling) strongly affects the quality (scratch and latent scratch) of the polished surface, and this needs to be evaluated.
Thus, according to the knowledge of the present inventors, as described in each of the above patent publications, when the primary particles are simply coarse particles, the particle size and amount of the aggregate particles in the dry state are determined. Simply defining it is quite insufficient to assess the quality of the abrasive particles to the level of latent scratches.
(Method for separating and concentrating coarse particles in abrasive particles)
In the present invention, in evaluating the strength of aggregation of the coarse particles in the abrasive particles in the aqueous medium, first, the coarse particles obtained by separating and concentrating the coarse particles present in a trace amount in the abrasive particles are obtained. Is evaluated for the strength of aggregation.
As a method for separating and concentrating a small amount of coarse particles in the abrasive particles, the method is performed by utilizing the difference in the sedimentation rate for each particle size of the abrasive particles in water. Examples of specific methods are described below. That is,
200 g of abrasive particles are added to 10 L of water containing 120 (mg / L) sodium pyrophosphate (dispersant), and dispersed by stirring. After standing for 30 minutes, the supernatant is gently extracted. Next, water containing 120 (mg / L) sodium pyrophosphate is newly added until the original liquid volume is reached, and the same operation is repeated 5 times. Coarse particles finally deposited on the bottom of the container are collected to form a dry powder. The particle diameter of the coarse particles is approximately 10 μm (= α ₀ ) or more.
By dividing the mass of the coarse particles by the mass of the first abrasive particles, the abundance ratio of the coarse particles (here, about 10 μm or more) in the abrasive particles is calculated.
(Evaluation method of flocculation of separated and concentrated coarse particles and calculation of ξ)
Aggregate particles in the present invention (here, those having a particle diameter of 10 μm) are irradiated with ultrasonic waves as follows, and the dispersion ratio ξ is set to Thus, the calculation is performed. That is,
Into a beaker containing 50 mL of water, 50 mg of the separated and concentrated coarse particles are added. Next, 1.8 L of water is put into an ultrasonic irradiation bath having a volume of 2.6 L, and a beaker containing 50 mL of the water and 50 mg of coarse particles is immersed therein. An ultrasonic wave with a frequency of 38 KHz and an output of 190 W (manufactured by AS ONE, trade name: use of ultrasonic cleaner US-2) is irradiated for 10 minutes. The particle size distribution (volume basis) of the particles before and after the ultrasonic irradiation was measured by a laser scattering method with a laser scattering measuring instrument (for example, Nikkiso Co., Ltd., trade name: Microtrack, Model 9320-X100), and the particle diameter was 10 μm. The dispersion ratio ξ of the above particles by ultrasonic irradiation is calculated by the equation (1).
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
In the present invention, the dispersion ratio ξ is at least 30 (%) or more, preferably 50 (%) or more, more preferably 70 (%) or more, and most preferably 80 (%) or more, as shown in the Examples below. .
Accordingly, abrasive particles having a dispersion ratio ξ measured by the method of formula (1) having a specific value ξ ₀ (%), for example, 30 (%) or more, are adjusted, selected or discriminated and used for glass polishing. Thus, it is possible to polish the glass under conditions with few latent scratches.
(Abrasive particles)
When the composition of the main component of the abrasive particles in the present invention is expressed in terms of mass% in terms of oxide, for example, CeO ₂ 50 to 65%, La ₂ O ₃ 25 to 35%, Pr ₆ O ₁₁ 5 to 6.5%. Nd ₂ O ₃ is preferably about 0.3 to 15%. That is, it is made of so-called mixed oxide rare earth particles.
3-9 mass% is preferable, and, as for content of the fluorine content (F) in the abrasive particle in this invention, More preferably, it is 5-8 mass%. In general, when the content of fluorine (F) is too small, lanthanum oxide, which is strongly basic, cannot be sufficiently changed or fixed to lanthanum fluoride, so that the polishing rate becomes slow. On the other hand, when the fluorine content (F) is too large, excess rare earth fluoride causes sintering during firing, which is not desirable.
The average particle diameter (d ₅₀ ) of the abrasive particles in the present invention is preferably 0.3 to 3 μm, more preferably 0.5 to 2 μm, and even more preferably 0.5 to 1.5 μm. The average particle diameter is measured by a laser scattering method (for example, manufactured by Nikkiso Co., Ltd., laser scattering method, trade name: Microtrac, model: 9320-X100 type used).
Further, regarding the particle size distribution of the abrasive particles, in the cumulative particle size distribution, d ₉₀ / d ₁₀ when the particle sizes (μm) of 10% and 90% from the small particle size are d ₁₀ and d ₉₀ , respectively. , 15 or less is preferable, 10 or less is more preferable, and 5 or less is most preferable.
Regarding the crystallographic physical properties of the abrasive particles, 2θ is the maximum peak (A) of the cubic complex oxide rare earth and 2θ in the vicinity of 28.3 deg in the crystal peak by powder X-ray diffraction analysis using CuKα ray. However, although the peak (B) of rare earth oxyfluoride appears in the vicinity of 26.6 deg, the ratio of the peak height of B / A of these two peaks is preferably 0.2 to 0.8. 3-0.6 are more preferable.
Here, the “peak height” indicates the height from the baseline of the peak curve to the peak apex (the same applies hereinafter).
Furthermore, the other physical properties of the rare earth oxide mainly composed of cerium are as follows.
The crystallite diameter (by the Scherrer method) is preferably 150 to 300 mm, more preferably 170 to 250 mm.
The pore structure of the abrasive particles is preferably 1 to 10 (m ² / g) as the specific surface area by the BET method (for example, manufactured by Shimadzu Corporation, apparatus name: measured by Micro Merits Flow SorbII 2300). More preferably, 5-6 (m < ² > / g).
(Metal sulfate content)
The content of the metal sulfate in terms of SO ₄ in the abrasive particles in the present invention is preferably 0.070 (mol / Kg) or less, more preferably 0.050 (mol / Kg) or less, and 0.035 ( Mol / Kg) or less is most preferred.
In the present invention, the SO ₄ analysis method is based on a method in which abrasive particles are dissolved in an aqueous solution containing nitric acid and hydrogen peroxide, and S is analyzed by an inductively coupled plasma emission spectrometer (ICP). is there.
The metal elements of metal sulfates are mainly alkaline earth metals such as calcium, magnesium, and barium, and lanthanum in light rare earth elements. The sulfates of these elements are abrasives described later. Even in the calcination step during the production process of the particles, it is not completely pyrolyzed and remains in the form of sulfate.
According to the finding of the present inventors, the amount of metal sulfate in terms of SO ₄ has a great correlation with the ease of loosening of the abrasive aggregate particles.
This is because, in the above firing step, when the sulfates of these elements are present in a specific amount or more as described above, the aggregated particles subjected to the firing treatment cause weak sintering, so the aggregation strength of the aggregated particles increases. It is thought to do. Further, when the sulfate is above a specific amount, the mechanical strength of the aggregate particles increases. Therefore, when the aggregate particles of the abrasive are dispersed in an aqueous medium, The mechanical force such as a normal shearing force that is applied makes it difficult to disintegrate or disperse, so that the aggregate is considered to be difficult to loosen as a phenomenon. The amount of the metal sulfate in terms of SO ₄ is preferably small from the above viewpoint, but it is not necessary to completely remove it, and the object of the present invention can be achieved by adjusting the content to the numerical value or less. It is enough from a point.
Then, as shown in Examples below, for example, by setting the amount of metal sulfate to 0.070 (mol / Kg) or less, the dispersion ratio ξ = 30 (%) or more can be secured, and further, metal sulfate. By setting the amount of salt to 0.050 (mol / Kg) or less, the dispersion ratio ξ = 50 (%) or more can be secured.
(Manufacture of abrasive particles)
The abrasive in the present invention, particularly the abrasive particles having a dispersion ratio (ξ) in the range specified in the present invention, is produced by the following method.
The raw material of the abrasive mainly composed of cerium oxide in the present invention is mainly produced from rare earth-containing ores such as bastonite, monazite, xenotime, Chinese complex ore, of course, but is not limited thereto. Absent.
First, after selecting these rare earth-containing ores, rare earth concentrates such as bastonite concentrate, monazite concentrate, and China complex concentrate are obtained, and the obtained rare earth concentrate is filled with unnecessary minerals such as radioactive elements. Carbon dioxide, which is a raw material for abrasives mainly composed of cerium oxide, is combined with conventional processes such as precipitation filtration and further firing after chemical treatment for removal and, if necessary, solvent extraction. A raw material for an abrasive material such as rare earth, rare earth oxide, rare earth hydroxide, rare earth fluoride and the like is obtained.
In the case of rare earth fluoride, a method is generally used in which hydrofluoric acid is added to an aqueous solution of rare earth chloride to produce a precipitate of rare earth fluoride.
An example of a preferable method for producing abrasive particles in the present invention is not limited to this, but a method using a rare earth oxide and a rare earth fluoride obtained by thermally decomposing a rare earth carbonate as a starting material. is there. That is,
First, the rare earth carbonate obtained from the above ore is fired (calcined) in an oxygen-containing atmosphere at 400 to 840 ° C. for 30 minutes to 48 hours, preferably about 1 to 24 hours, and thermally decomposed. Use oxidized rare earth. As described above, it is one of the preferable steps that the rare earth carbonate is not fired suddenly (main firing) but is calcined at a temperature lower than the main firing temperature described later to obtain oxidized rare earth. Note that a part of the rare earth carbonate may remain in the rare earth oxide.
Here, as a mixture of oxidized rare earth and rare earth carbonate obtained by calcining rare earth carbonate (preliminary firing), oxide-converted total rare earth (TREO) is preferably 50 to 97% by mass. 70 to 95% by mass is more preferable, and 80 to 93% by mass is even more preferable.
On the other hand, as described above, it is possible to use a fluorinated rare earth obtained by a general production method in which a hydrofluoric acid is added to a rare earth chloride aqueous solution to produce a precipitate of the fluorinated rare earth. Although it is preferable, of course, it is not limited to this.
The calcined oxidized rare earth is usually subjected to steps such as rare earth fluoride addition, raw material mixture slurrying, wet grinding, drying, firing, crushing, and classification as follows.
First, a rare earth fluoride is added to the rare earth oxide obtained by the above calcination. The addition amount of the rare earth fluoride is preferably such that the content in the abrasive particles finally obtained is 3 to 9% by mass as (F) conversion amount, as already described, 5-8 mass% is more preferable (fluorinated rare earth addition process).
Thus, after adding the rare earth fluoride to the rare earth oxide, water is added and mixed to obtain a slurry having a solid content concentration of 30 to 60% by mass. The slurry is wet pulverized for about 1 to 10 hours to obtain a particle size of 0. The slurry is made of particles of about 2 to 10 μm (raw material mixing slurry, wet pulverization step).
Next, the wet pulverized slurry is dried and then fired in an oxygen-containing atmosphere. This calcination should be referred to as main calcination with respect to the above-mentioned calcination, and as a calcination condition, a heating rate of 500 ° C. or higher is maintained at 0.3 to 5 (° C./min). As high temperature, it is preferable that the holding time in 850-1100 degreeC and the said high temperature range shall be 0.5 to 6 hours.
Furthermore, as firing conditions, a heating rate of 500 ° C. or higher is 0.5 to 3.5 (° C./min), and a high temperature to be held is 900 to 1000 ° C. and in the high temperature range. The holding time is more preferably 2 to 5 hours.
As a baking apparatus for carrying out calcination or main baking, if the above-mentioned pulverized / dried raw materials are accommodated, the temperature is raised at the temperature specified here, and the high temperature can be held and baked, Any type of furnace may be used. For example, a batch type or continuous type box furnace, rotary furnace, tunnel furnace or the like can be applied. Any of the formulas (fuel is gas or fuel oil, etc.) can be applied (drying and firing steps).
Thus, after firing, it is crushed and classified as desired to obtain abrasive particles having a predetermined particle diameter range (pulverization and classification step).
Instead of separately preparing and mixing rare earth oxides and rare earth fluorides as described above, it is also possible to employ a method in which a rare earth carbonate is used as a raw material and a part thereof is partially fluorinated with an aqueous hydrofluoric acid solution. Is possible. In the case of this production method, water is added to a rare earth carbonate to form a slurry, and hydrogen fluoride is added to this to partially fluorinate it. What is necessary is just to perform processes, such as crushing and classification.
(Adjustment of metal sulfate content)
In the present invention, as already described, the content of the metal sulfate in terms of SO ₄ present in the abrasive particles is 0.070 (mol / Kg) or less, preferably 0.050 (mol / Kg). ), More preferably 0.035 (mol / Kg) or less.
To the content of SO ₄ Conversion metal sulfate present in the abrasive particles in the above range is not particularly limited, for example, the following method can be adopted. That is, one is to adjust the purity of the light rare earth material used as the raw material so that it falls within the above specified range, and to put the SO ₄ equivalent content in the obtained abrasive material in the above preferred range. is there. Alternatively, after obtaining a light rare earth material used as a raw material with a small SO ₄ equivalent content, polishing a metal sulfate (eg, calcium sulfate, magnesium sulfate, etc.) such as an alkaline earth metal with an added amount adjusted. Mixing and coexisting in advance in the process of manufacturing the material particles, applying the manufacturing process described above so that the SO ₄ equivalent content present in the abrasive particles is in the above preferred range You may employ | adopt the means to adjust.
(Abrasive composition, pH of slurry, etc.)
In the present invention, the abrasive particles are used as a water slurry. Regarding the pH of the water slurry, the pH of the water slurry having a solid concentration of 10% by mass at room temperature is preferably 6.0 to 9.0. 2 to 8.0 is more preferable, and 6.5 to 7.5 is most preferable.
In the abrasive slurry in the present invention, an organic polymer dispersant such as a polymer polycarboxylic acid ammonium salt or a polymer polysulfonate ammonium is added to the aqueous medium to improve the dispersibility of the particles. May be used. As already described, the SO ₄ analysis method involves dissolving abrasive particles in an aqueous solution containing nitric acid and hydrogen peroxide, and using an inductively coupled plasma emission spectrometer (ICP), S (emission line wavelength). : 180.731 nm).
(The invention's effect)
According to the present invention, in a glass polishing abrasive, particularly a glass polishing abrasive mainly composed of a rare earth oxide containing cerium oxide, while maintaining a high polishing rate, scratches generated on the glass to be polished, particularly latent There is provided an abrasive for polishing glass, in which scratches are reduced to an unprecedented level. In addition, according to the present invention, there is provided a quality evaluation method capable of accurately evaluating the quality of the abrasive particles, particularly with respect to latent scratches, with respect to the powder.
In an actual polishing plant, the abrasive composition of the present invention is used as an abrasive aqueous medium dispersion (so-called abrasive slurry). However, when the abrasive slurry is used, it has been a problem in the past. It was confirmed that there was an unexpected effect that deposition due to sedimentation in the slurry flow path was significantly reduced.

なお、表１における比較例１の研磨材の研磨速度のレベルは、セイミケミカル社製の高速度レート対応品（商品名：ルミノックスＴＥ−３０３）に準じたレベルに設定してあり、表において実施例１〜６、比較例２の研磨速度は、すべて比較例１を基準としてこれとほぼ同等の高いレベルを維持している。  Hereinafter, the present invention will be described by way of examples. However, these are merely examples of embodiments, and the technical scope of the present invention is not construed as being limited thereto. Unless otherwise specified, “%” means “% by mass”.
[Example 1] (SO in abrasive particles₄Content 0.015 (mol / Kg) (= 0.144 mass%))
(Preparation of abrasive particles)
(I) As a raw material, carbonic acid rare earth from China [total rare earth oxide (TREO) 42 mass%, CeO₂/ TREO 60% by mass, SO₄Content: 0.063% by mass] 45 kg is put in a Saya container (made of mullite), heated in an air atmosphere at a heating temperature of 750 ° C. for 2 hours (calcined), and converted to oxide-reduced all rare earth (TREO) 90. 5% by mass, SO₄An oxidized rare earth fired product having a content of 0.063% by mass was obtained.
(Ii) Next, 16 kg of the calcined product and a rare earth fluoride from China [total rare earth oxide (TREO) 83 mass%, CeO₂/ TREO 61% by mass, F content 25% by mass, SO₄Content: 0.125% by mass, average particle size: 10 μm] 5.0 kg was weighed and both were put into a stirring tank containing 27.2 kg of water and stirred to form a slurry. Next, the slurry was circulated and supplied to a wet pulverizer using a pulverization medium ball, and wet pulverized for about 5 hours, and the particle size was pulverized to 0.2 to 6 μm.
(Iii) The slurry after wet pulverization was put into a vat and dried at 120 ° C. for 20 hours with a box-type dryer. The dried powder was put in a Saya container (Mullite) and fired in an air atmosphere. That is, firing was performed under the conditions of a heating rate of 500 ° C. or higher at 2.3 (° C./min), a high temperature to be held at 950 ° C., and a holding time at the above temperature of 3.0 hours. . The fired powder was pulverized by a pulverizer and then classified using an air classifier to obtain 14.0 kg of abrasive particles.
(Particle composition and various physical properties)
(I) When the composition of the abrasive particles is expressed in terms of oxide mass%,
TREO (= CeO₂+ La₂O₃+ Nd₂O₃+ Pr₆O₁₁) 95.3% by mass, and the mass ratio of each oxide to TREO is CeO₂  62.1%, La₂O₃  30.4%, Pr₆O₁₁  6.5%, Nd₂O₃  The content of 1.0% and fluorine content (F) was 5.7%. Also, SO₄The content was 0.015 (mol / Kg) (= 0.14.4% by mass).
(Ii) Average particle diameter (d₅₀) Was 0.95 μm (measured by a laser scattering method using a laser scattering measuring device (manufactured by Nikkiso Co., Ltd., trade name: Microtrack, model 9320-X100)). The particle size distribution was measured in the same manner in the following examples and comparative examples.
Regarding the particle size distribution, in the cumulative particle size distribution, the particle sizes (μm) of 10% and 90% from the small particle size are d, respectively.₁₀, D₉₀D₉₀/ D₁₀Was 3.2.
(Iii) X-ray diffraction spectrum analysis results of the particles using a powder X-ray diffraction device (manufactured by Rigaku Corporation, CuKα ray, Rint-2000 type, the same in the following examples and comparative examples) are as follows: It is.
  The maximum peak (A) of the cubic complex oxide rare earth appears at 2θ near 28.3 deg, and the peak (B) of the oxyfluoride rare earth appears at 2θ near 26.6 deg (in the following examples, In the comparative example, the two peak appearances 2θ were substantially the same). The ratio of the peak height (B) to the peak height (A) (B / A) was 0.49.
In the X-ray diffraction analysis measurement, no crystal peak of cerium fluoride was observed.
(Iv) Other physical properties of the particles are as follows.
a) The crystallite diameter (Scherrer method) was 197 mm.
b) Specific surface area of particles by the BET method (Shimadzu Corporation, measurement by apparatus name Micro Merits Flow SorbII 2300, the same in the following Examples and Comparative Examples) is 2.8 (m²/ G).
c) The pH of the aqueous slurry of the particles (solid concentration: 10% by mass, the same in the following Examples and Comparative Examples) was 7.0.
d) Particle size of 10 μm (= α) that particularly affects the scratches on the polished surface of glass.₀) In evaluating the cohesive strength of the above particles, the coarse particles in the abrasive particles are separated and concentrated by the following method, and the coarse particles are dispersed in water and irradiated with ultrasonic waves. The dispersion ratio ξ to be crushed and dispersed by sonication was determined from the change in the particle size distribution (volume basis) before and after the sonication by Equation (1).
  Here, the separation and concentration of the coarse particles in the abrasive particles were performed as follows (the same applies to the following examples and comparative examples) according to the method described above. That is, 200 g of abrasive particles are added to 10 L of water containing 120 (mg / L) sodium pyrophosphate (dispersing agent), stirred and dispersed, allowed to stand for 30 minutes, and then the supernatant is gently extracted. Next, water containing 120 (mg / L) sodium pyrophosphate is newly added until the original liquid volume is reached, and the same operation is repeated 5 times. Coarse particles finally deposited on the bottom of the container were collected to obtain a dry powder.
50 mg of the separated and concentrated coarse particles are added to a beaker containing 50 mL of water. Next, 1.8 L of water is put into an ultrasonic irradiation bath having a volume of 2.6 L, and the above beaker is immersed therein. Using an ultrasonic cleaner (manufactured by ASONE, trade name: ultrasonic cleaner US-2), ultrasonic waves with a frequency of 38 KHz and an output of 190 W are irradiated for 10 minutes.
  The particle size distribution (volume basis) of the particles before and after the ultrasonic irradiation is measured by a laser scattering method using a laser scattering measuring machine (for example, Nikkiso Co., Ltd., trade name: Microtrac, 9320-X100 type). The dispersion ratio ξ by ultrasonic irradiation of particles having a size of 10 μm or more was determined by the equation (1).
  ξ = [(V₀-V_t) / V₀] X 100 (%) (1)
(Where V₀Is the particle size α before ultrasonic irradiation₀Abundance of particles (= 10 μm) or more (cumulative volume), V_tIs the above α after ultrasonic irradiation₀The abundance of particles (= 10 μm) or more (cumulative volume) is shown. )
The dispersion ratio ξ by ultrasonic irradiation of particles of 10 μm or more determined by the above method was 78%.
(Polishing test)
  The polishing test was performed by the following method and conditions (the same applies to the following examples and comparative examples). As a polishing test machine, a double-side polishing machine WS-6PB manufactured by World Wrap Co., Ltd. was used. The glass plate to be polished used for the test was non-alkali glass (trade name: AN-100, SiO in glass composition) manufactured by Asahi Glass Co., Ltd.₂A content of about 60% by mass and a test plate size (square): 70 mm / 70 mm / 0.7 mm in size) were used.
  The polishing pad is made of polyurethane foam, and the polishing pressure is 92 (g / cm²Then, the polishing test was carried out with the lower surface plate rotation speed of 70 rpm fixed and the rotation speed ratio of the upper surface plate and the lower surface plate being 1: 3. The concentration of the abrasive in the abrasive slurry was 20% by mass.
(Evaluation method for scratches (latent scratches) on the polished surface)
  The method for evaluating fine scratches on the glass surface after being polished was carried out by the following method (the same applies to the following examples and comparative examples).
  The polished glass is immersed for 30 seconds in a HF aqueous solution having a concentration of 0.1% by mass placed in a resin vat. The glass plate is pulled up with tweezers and immediately washed thoroughly with pure water, and then the glass plate is dried.
  Next, the polished surface of the glass was observed and evaluated with a dark field microscope (manufactured by Olympus, system metal microscope, BHT type, 100 times).
The polished glass surface was suitable for evaluation of latent scratches with no large scratches or fine scratches in the following three-stage evaluation.
Evaluation of latent injury: Evaluation in the following three stages (same in Examples and Comparative Examples)
: Neither a big crack nor a fine crack is recognized at all, it is an unprecedented level, and is judged to be extremely suitable as an abrasive.
: Large scratches are not recognized, and there are very few fine scratches, which is a considerable level, and is judged to be suitable as an abrasive.
X: There are almost no large scratches, but there are a large number of fine scratches, and it is judged to be unsuitable as an abrasive.
(Test results)
  SO in abrasive₄Table 1 shows the converted content, the dispersion ratio ξ by ultrasonic irradiation, and the evaluation results of the glass surface after the polishing test.
[Example 2] (SO in abrasive particles₄Content 0.021 (mol / Kg) (= 0.202 mass%))
(Preparation of abrasive particles)
(I) As a raw material, carbonic acid rare earth from China [total rare earth oxide (TREO) 42 mass%, CeO₂/ TREO 60% by mass, SO₄Content: 0.089% by mass] 45 kg is put in a Saya container (Mullite), heated in an air atmosphere at a heating temperature of 750 ° C. for 2 hours (calcined), and oxide-converted all rare earth (TREO) 90. 8% by mass, SO₄An oxidized rare earth fired product having a content of 0.192% by mass was obtained.
(Ii) Next, 16 kg of the calcined product and a rare earth fluoride from China [total rare earth oxide (TREO) 83 mass%, CeO₂/ TREO 61% by mass, F content 25% by mass, SO₄Content: 0.175% by mass, average particle size: 10 μm] 5.0 kg was weighed and both were put into a stirring tank containing 27.2 kg of water and stirred to form a slurry. Next, the slurry was circulated and supplied to a wet pulverizer using a pulverization medium ball, and wet pulverized for about 5 hours, and the particle size was pulverized to 0.2 to 6 μm.
(Iii) The slurry after wet pulverization was put into a vat and dried at 120 ° C. for 20 hours with a box-type dryer. The dried powder was put in a Saya container (Mullite) and fired in an air atmosphere. That is, firing was performed under the conditions of a heating rate of 500 ° C. or higher at 2.3 (° C./min), a high temperature to be held at 950 ° C., and a holding time at the above temperature of 3.0 hours. . The fired powder was pulverized with a pulverizer and then classified with an air classifier to obtain 13.8 kg of abrasive particles.
(Particle composition and various physical properties)
(I) When the composition of the abrasive particles is expressed in terms of oxide mass%,
TREO (= CeO₂+ La₂O₃+ Nd₂O₃+ Pr₆O₁₁) 95.7% by mass, the mass ratio of each of the above oxides to TREO is CeO₂  62.1%, La₂O₃  30.4%, Pr₆O₁₁  6.5%, Nd₂O₃  The content of 1.0% and fluorine content (F) was 5.9%. Also, SO₄The content was 0.021 (mol / Kg) (= 0.02 mass%).
(Ii) Average particle diameter (d₅₀) Was 0.93 μm.
For the particle size distribution, d₉₀/ D₁₀Was 3.8.
(Iii) The ratio of the peak height (B) to the peak height (A) (B / A) was 0.50.
In the X-ray diffraction analysis measurement, no crystal peak of cerium fluoride was observed.
(Iv) Other physical properties of the particles are as follows.
a) The crystallite diameter (Scherrer method) was 200 mm.
b) The specific surface area of the particles by the BET method is 3.0 (m²/ G).
c) The pH of the water slurry of the particles was 7.1.
  The dispersion ratio ξ by ultrasonic irradiation of particles of 10 μm or more was evaluated by the same method as in Example 1.
  The glass polishing test and the evaluation of the glass surface after polishing were evaluated in the same manner as in Example 1. SO in abrasive₄Table 1 shows the converted content, the dispersion ratio ξ by ultrasonic irradiation, and the evaluation results of the glass surface after the polishing test.
[Example 3] (SO in abrasive particles₄Content 0.045 (mol / Kg) (= 0.432 mass%))
(Preparation of abrasive particles)
(I) As a raw material, carbonic acid rare earth from China [total rare earth oxide (TREO) 42 mass%, CeO₂/ TREO 60% by mass, SO₄Content: 0.190% by mass] 45 kg is put in a Saya container (made of mullite), heated in an air atmosphere at a heating temperature of 750 ° C. for 2 hours (calcined), and converted into oxide-reduced all rare earth (TREO) 90. 8% by mass, SO₄An oxidized rare earth fired product having a content of 0.192% by mass was obtained.
(Ii) Next, 16 kg of the calcined product and a rare earth fluoride from China [total rare earth oxide (TREO) 83 mass%, CeO₂/ TREO 61% by mass, F content 25% by mass, SO₄Content 0.375% by mass, average particle size 10 μm] 5.0 kg was weighed, and both were put into a stirring tank containing 27.2 kg of water and stirred to form a slurry. Next, the slurry was circulated and supplied to a wet pulverizer using a pulverization medium ball, and wet pulverized for about 5 hours, and the particle size was pulverized to 0.2 to 6 μm.
(Iii) The slurry after wet pulverization was put into a vat and dried at 120 ° C. for 20 hours with a box-type dryer. The dried powder was put in a Saya container (Mullite) and fired in an air atmosphere. That is, firing was performed under the conditions of a heating rate of 500 ° C. or higher at 2.3 (° C./min), a high temperature to be held at 950 ° C., and a holding time at the above temperature of 3.0 hours. . The fired powder was pulverized with a pulverizer and then classified with an air classifier to obtain 14.1 kg of abrasive particles.
(Particle composition and various physical properties)
(I) When the composition of the abrasive particles is expressed in terms of oxide mass%,
TREO (= CeO₂+ La₂O₃+ Nd₂O₃+ Pr₆O₁₁) 95.5 mass%, the mass ratio of each of the above oxides relative to TREO is CeO₂  61.2%, La₂O₃  31.9%, Pr₆O₁₁  6.0%, Nd₂O₃  The content of 0.9% and fluorine content (F) was 5.7%. Also, SO₄The content was 0.045 (mol / Kg) (= 0.432 mass%).
(Ii) Average particle diameter (d₅₀) Was 0.95 μm.
For the particle size distribution, d₉₀/ D₁₀Was 4.2.
(Iii) The peak height ratio (B / A) of the peak height (B) to the peak height (A) was 0.45.
In the X-ray diffraction analysis measurement, no crystal peak of cerium fluoride was observed.
(Iv) Other physical properties of the particles are as follows.
a) The crystallite diameter (Scherrer method) was 205 mm.
b) The specific surface area of the particles by the BET method is 2.8 (m²/ G).
c) The pH of the water slurry of the particles was 7.0.
SO in abrasive₄Table 1 shows the converted content, the dispersion ratio ξ by ultrasonic irradiation, and the evaluation results of the glass surface after the polishing test.
[Example 4] (SO in abrasive particles₄Content 0.010 (mol / Kg) (= 0.096 mass%))
(Preparation of abrasive particles)
(I) As a raw material, carbonic acid rare earth from China [total rare earth oxide (TREO) 42 mass%, CeO₂/ TREO 60% by mass, SO₄Content of 0.042% by mass] 45 kg is put in a Saya container (made of mullite), heated in an air atmosphere at a heating temperature of 750 ° C. for 2 hours (calcined), and converted to oxide-reduced all rare earth (TREO) 90. 8% by mass, SO₄An oxidized rare earth fired product having a content of 0.192% by mass was obtained.
(Ii) Next, 16 kg of the calcined product and a rare earth fluoride from China [total rare earth oxide (TREO) 83 mass%, CeO₂/ TREO 61% by mass, F content 25% by mass, SO₄Content: 0.083% by mass, average particle size: 10 μm] 5.0 kg was weighed, and both were put into a stirring tank containing 27.2 kg of water and stirred to form a slurry. Next, the slurry was circulated and supplied to a wet pulverizer using a pulverization medium ball, and wet pulverized for about 5 hours, and the particle size was pulverized to 0.2 to 6 μm.
(Iii) The slurry after wet pulverization was put into a vat and dried at 120 ° C. for 20 hours with a box-type dryer. The dried powder was put in a Saya container (Mullite) and fired in an air atmosphere. That is, firing was performed under the conditions of a heating rate of 500 ° C. or higher at 2.3 (° C./min), a high temperature to be held at 950 ° C., and a holding time at the above temperature of 3.0 hours. . The fired powder was pulverized by a pulverizer and then classified using an air classifier to obtain 13.9 kg of abrasive particles.
(Particle composition and various physical properties)
(I) When the composition of the abrasive particles is expressed in terms of oxide mass%,
TREO (= CeO₂+ La₂O₃+ Nd₂O₃+ Pr₆O₁₁) 95.5 mass%, the mass ratio of each of the above oxides relative to TREO is CeO₂  61.2%, La₂O₃  31.9%, Pr₆O₁₁  6.0%, Nd₂O₃  The content of 0.9% and fluorine content (F) was 5.7%. Also, SO₄The content was 0.010 (mol / Kg) (= 0.096 mass%).
(Ii) Average particle diameter (d₅₀) Was 0.93 μm.
For the particle size distribution, d₉₀/ D₁₀Was 5.0.
(Iii) The ratio of the peak height (B) to the peak height (A) (B / A) was 0.44.
In the X-ray diffraction analysis measurement, no crystal peak of cerium fluoride was observed.
(Iv) Other physical properties of the particles are as follows.
a) The crystallite diameter (Scherrer method) was 203 mm.
b) Specific surface area of the particles by BET method is 2.7 (m²/ G).
c) The pH of the water slurry of the particles was 7.1.
SO in abrasive₄Table 1 shows the converted content, the dispersion ratio ξ by ultrasonic irradiation, and the evaluation results of the glass surface after the polishing test.
[Example 5] (SO in abrasive particles₄Content 0.003 (mol / Kg) (= 0.029 mass%))
(Preparation of abrasive particles)
(I) As a raw material, carbonic acid rare earth from China [total rare earth oxide (TREO) 42 mass%, CeO₂/ TREO 60% by mass, SO₄Content 0.013 mass%] 45 kg is put in a Saya container (made of mullite), heated in an air atmosphere at a heating temperature of 750 ° C. for 2 hours (calcination), and converted into an oxide-converted all rare earth (TREO) 90. 8% by mass, SO₄An oxidized rare earth fired product having a content of 0.192% by mass was obtained.
(Ii) Next, 16 kg of the calcined product and a rare earth fluoride from China [total rare earth oxide (TREO) 83 mass%, CeO₂/ TREO 61% by mass, F content 25% by mass, SO₄Content: 0.025% by mass, average particle size 10 μm] 5.0 kg was weighed, and both were put into a stirring tank containing 27.2 kg of water and stirred to form a slurry. Next, the slurry was circulated and supplied to a wet pulverizer using a pulverization medium ball, and wet pulverized for about 5 hours, and the particle size was pulverized to 0.2 to 6 μm.
(Iii) The slurry after wet pulverization was put into a vat and dried at 120 ° C. for 20 hours with a box-type dryer. The dried powder was put in a Saya container (Mullite) and fired in an air atmosphere. That is, firing was performed under the conditions of a heating rate of 500 ° C. or higher at 2.3 (° C./min), a high temperature to be held at 950 ° C., and a holding time at the above temperature of 3.0 hours. . The fired powder was pulverized by a pulverizer and then classified using an air classifier to obtain 14.0 kg of abrasive particles.
(Particle composition and various physical properties)
(I) When the composition of the abrasive particles is expressed in terms of oxide mass%,
TREO (= CeO₂+ La₂O₃+ Nd₂O₃+ Pr₆O₁₁) 95.4 mass%, the mass ratio of each of the above oxides relative to TREO is CeO₂  61.1%, La₂O₃  31.9%, Pr₆O₁₁  6.0%, Nd₂O₃  The content of 1.0% and fluorine content (F) was 5.6%. Also, SO₄The content was 0.003 (mol / Kg) (= 0.029% by mass).
(Ii) Average particle diameter (d₅₀) Was 0.93 μm.
For the particle size distribution, d₉₀/ D₁₀Was 3.5.
(Iii) The ratio of the peak height (B) to the peak height (A) (B / A) was 0.44.
In the X-ray diffraction analysis measurement, no crystal peak of cerium fluoride was observed.
(Iv) Other physical properties of the particles are as follows.
a) The crystallite diameter (Scherrer method) was 195 mm.
b) The specific surface area of the particles by the BET method is 2.9 (m²/ G).
c) The pH of the water slurry of the particles was 7.1.
SO in abrasive₄Table 1 shows the converted content, the dispersion ratio ξ by ultrasonic irradiation, and the evaluation results of the glass surface after the polishing test.
[Example 6] (SO in abrasive particles₄Content 0.070 (mol / Kg) (= 0.672 mass%))
(Preparation of abrasive particles)
(I) As a raw material, carbonic acid rare earth from China [total rare earth oxide (TREO) 42 mass%, CeO₂/ TREO 60% by mass, SO₄Content: 0.296% by mass] 45 kg is put in a Saya container (made of mullite), heated in an air atmosphere at a heating temperature of 750 ° C. for 2 hours (calcined), and converted into oxide-reduced all rare earth (TREO) 90. 8% by mass, SO₄An oxidized rare earth fired product having a content of 0.640% by mass was obtained.
(Ii) Next, 16 kg of the calcined product and a rare earth fluoride from China [total rare earth oxide (TREO) 83 mass%, CeO₂/ TREO 61% by mass, F content 25% by mass, SO₄Content: 0.584% by mass, average particle size: 10 μm] 5.0 kg was weighed, and both were put into a stirring tank containing 27.2 kg of water and stirred to form a slurry. Next, the slurry was circulated and supplied to a wet pulverizer using a pulverization medium ball, and wet pulverized for about 5 hours, and the particle size was pulverized to 0.2 to 6 μm.
(Iii) The slurry after wet pulverization was put into a vat and dried at 120 ° C. for 20 hours with a box-type dryer. The dried powder was put in a Saya container (Mullite) and fired in an air atmosphere. That is, firing was performed under the conditions of a heating rate of 500 ° C. or higher at 2.3 (° C./min), a high temperature to be held at 950 ° C., and a holding time at the above temperature of 3.0 hours. . The fired powder was pulverized with a pulverizer and then classified with an air classifier to obtain 14.1 kg of abrasive particles.
(Particle composition and various physical properties)
(I) When the composition of the abrasive particles is expressed in terms of oxide mass%,
TREO (= CeO₂+ La₂O₃+ Nd₂O₃+ Pr₆O₁₁) 95.7% by mass, the mass ratio of each of the above oxides to TREO is CeO₂  63.0%, La₂O₃  29.9%, Pr₆O₁₁  6.0%, Nd₂O₃  The content of 1.1% and fluorine content (F) was 5.6%. Also, SO₄The content was 0.070 (mol / Kg) (= 0.672 mass%).
(Ii) Average particle diameter (d₅₀) Was 0.93 μm.
For the particle size distribution, d₉₀/ D₁₀Was 3.8.
(Iii) The ratio of the peak height (B) to the peak height (A) (B / A) was 0.47.
In the X-ray diffraction analysis measurement, no crystal peak of cerium fluoride was observed.
(Iv) Other physical properties of the particles are as follows.
a) The crystallite size (Scherrer method) was 208 mm.
b) Specific surface area of the particles by BET method is 2.7 (m²/ G).
c) The pH of the water slurry of the particles was 7.1.
SO in abrasive₄Table 1 shows the converted content, the dispersion ratio ξ by ultrasonic irradiation, and the evaluation results of the glass surface after the polishing test.
[Comparative Example 1] (SO in abrasive particles₄Content 0.085 (mol / Kg) (= 0.816% by mass))
(Preparation of abrasive particles)
(I) As a raw material, carbonic acid rare earth from China [total rare earth oxide (TREO) 42 mass%, CeO₂/ TREO 60% by mass, SO₄Content: 0.359% by mass] 45 kg is put in a Saya container (Mullite), heated in an air atmosphere at a heating temperature of 750 ° C. for 2 hours (calcined), and converted into an oxide-converted all rare earth (TREO) 90. 5% by mass, SO₄An oxidized rare earth fired product having a content of 0.774% by mass was obtained.
(Ii) Next, 16 kg of the calcined product and a rare earth fluoride from China [total rare earth oxide (TREO) 83 mass%, CeO₂/ TREO 61% by mass, F content 25% by mass, SO₄Content: 0.709% by mass, average particle size: 10 μm] 5.0 kg was weighed, and both were put into a stirring tank containing 27.2 kg of water and stirred to form a slurry. Next, the slurry was circulated and supplied to a wet pulverizer using a pulverization medium ball, and wet pulverized for about 5 hours, and the particle size was pulverized to 0.2 to 6 μm.
(Iii) The slurry after wet pulverization was put into a vat and dried at 120 ° C. for 20 hours with a box-type dryer. The dried powder was put in a Saya container (Mullite) and fired in an air atmosphere. That is, firing was performed under the conditions of a heating rate of 500 ° C. or higher at 2.3 (° C./min), a high temperature to be held at 950 ° C., and a holding time at the above temperature of 3.0 hours. . The fired powder was pulverized by a pulverizer and then classified using an air classifier to obtain 13.9 kg of abrasive particles.
(Particle composition and various physical properties)
(I) When the composition of the abrasive particles is expressed in terms of oxide mass%,
TREO (= CeO₂+ La₂O₃+ Nd₂O₃+ Pr₆O₁₁) 95.6% by mass, and the mass ratio of each oxide to TREO is₂  63.0%, La₂O₃  29.8%, Pr₆O₁₁  6.1%, Nd₂O₃  The content of 1.1% and fluorine content (F) was 5.6%. Also, SO₄The content was 0.085 (mol / Kg) (= 0.816% by mass).
(Ii) Average particle diameter (d₅₀) Was 0.93 μm.
For the particle size distribution, d₉₀/ D₁₀Was 4.0.
(Iii) The ratio of the peak height (B) to the peak height (A) (B / A) was 0.47.
In the X-ray diffraction analysis measurement, no crystal peak of cerium fluoride was observed.
(Iv) Other physical properties of the particles are as follows.
a) The crystallite size (Scherrer method) was 208 mm.
b) The specific surface area of the particles by the BET method is 2.9 (m²/ G).
c) The pH of the water slurry of the particles was 7.0.
SO in abrasive₄Table 1 shows the converted content, the dispersion ratio ξ by ultrasonic irradiation, and the evaluation results of the glass surface after the polishing test.
[Comparative Example 2] (SO in abrasive particles₄Content 0.160 (mol / Kg) (= 1.536 mass%))
(Preparation of abrasive particles)
(I) As a raw material, carbonic acid rare earth from China [total rare earth oxide (TREO) 42 mass%, CeO₂/ TREO 60% by mass, SO₄Content 0.676% by mass] 45 kg is put in a Saya container (made of mullite), heated in an air atmosphere at a heating temperature of 750 ° C. for 2 hours (calcined), and converted into oxide-reduced all rare earth (TREO) 90. 8% by mass, SO₄An oxidized rare earth fired product having a content of 1.461% by mass was obtained.
(Ii) Next, 16 kg of the calcined product and a rare earth fluoride from China [total rare earth oxide (TREO) 83 mass%, CeO₂/ TREO 61% by mass, F content 25% by mass, SO₄Content 1.335% by mass, average particle size 10 μm] 5.0 kg was weighed and both were put into a stirring tank containing 27.2 kg of water and stirred to form a slurry. Next, the slurry was circulated and supplied to a wet pulverizer using a pulverization medium ball, and wet pulverized for about 5 hours, and the particle size was pulverized to 0.2 to 6 μm.
(Iii) The slurry after wet pulverization was put into a vat and dried at 120 ° C. for 20 hours with a box-type dryer. The dried powder was put in a Saya container (Mullite) and fired in an air atmosphere. That is, firing was performed under the conditions of a heating rate of 500 ° C. or higher at 2.3 (° C./min), a high temperature to be held at 950 ° C., and a holding time at the above temperature of 3.0 hours. . The fired powder was pulverized by a pulverizer and then classified using an air classifier to obtain 14.0 kg of abrasive particles.
(Particle composition and various physical properties)
(I) When the composition of the abrasive particles is expressed in terms of oxide mass%,
TREO (= CeO₂+ La₂O₃+ Nd₂O₃+ Pr₆O₁₁) 95.3% by mass, and the mass ratio of each oxide to TREO is CeO₂  62.0%, La₂O₃  30.5%, Pr₆O₁₁  6.5%, Nd₂O₃  The content of 1.0% and fluorine content (F) was 5.6%. Also, SO₄The content was 0.160 (mol / Kg) (= 1.536 mass%).
(Ii) Average particle diameter (d₅₀) Was 0.93 μm.
For the particle size distribution, d₉₀/ D₁₀Was 3.8.
(Iii) The ratio of the peak height (B) to the peak height (A) (B / A) was 0.50.
In the X-ray diffraction analysis measurement, no crystal peak of cerium fluoride was observed.
(Iv) Other physical properties of the particles are as follows.
a) The crystallite diameter (Scherrer method) was 210 mm.
b) The specific surface area of the particles by the BET method is 2.8 (m²/ G).
c) The pH of the water slurry of the particles was 7.0.
SO in abrasive₄Table 1 shows the converted content, the dispersion ratio ξ by ultrasonic irradiation, and the evaluation results of the glass surface after the polishing test.

  In addition, the level of the polishing rate of the abrasive of Comparative Example 1 in Table 1 is set to a level according to a high speed rate product (trade name: Luminox TE-303) manufactured by Seimi Chemical Co., Ltd. The polishing rates of Examples 1 to 6 and Comparative Example 2 are all maintained at a high level substantially equivalent to that of Comparative Example 1 as a reference.

According to the present invention, in particular, a polishing material for glass polishing mainly composed of a rare earth oxide containing cerium oxide, the polishing rate is sufficiently maintained to be comparable to a conventionally obtained high polishing rate, and polishing is performed. There is provided a polishing material for polishing a glass in which latent scratches generated in the glass to be reduced are reduced to an unprecedented level.
In addition, according to the present invention, there is provided a quality evaluation method capable of accurately evaluating the quality of the abrasive particles, particularly with respect to latent scratches, with respect to the powder.
Further, according to the present invention, when the abrasive particles of the present invention are used as an aqueous medium dispersion in an actual polishing plant, it is expected that deposition due to sedimentation in the slurry flow path, which has been a problem in the past, will be greatly reduced. It has an enormous effect, and its industrial applicability is extremely large.

Claims (10)

A method for evaluating the dispersibility of abrasive particles for glass polishing in an aqueous medium, comprising preparing an aqueous medium dispersion of abrasive particles obtained by adding abrasive particles to be measured to an aqueous medium, and performing the dispersion applying ultrasonic waves to liquid, represented by the formula (1), the relative abundance of the ultrasonic particular particle size before irradiation alpha _{0 ([mu]} m) or more particles, the alpha ₀ after ultrasonic irradiation _([mu] m) A quality evaluation method relating to the dispersibility of abrasive particles for glass polishing in an aqueous medium, characterized by measuring a rate of disappearance of the above particles by the action of ultrasonic irradiation (defined as dispersion rate (ξ)).
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).) A method of polishing glass with abrasive particles,
An aqueous medium dispersion of abrasive particles obtained by adding abrasive particles to be measured to an aqueous medium is prepared, and the dispersion is irradiated with ultrasonic waves. The ultrasonic irradiation represented by the formula (1) It is defined as the ratio (dispersion rate (ξ)) that disappears due to the ultrasonic irradiation effect of the particles of α ₀ (μm) or more after the ultrasonic irradiation with respect to the existing amount of particles of the specific particle diameter α ₀ (μm) or more. )
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
Adjusting, selecting or discriminating abrasive particles having a dispersion ratio ξ measured by the method of formula (1) equal to or higher than a specific value ξ ₀ (%);
A glass polishing method comprising performing glass polishing with the specified abrasive particles. The glass polishing method according to claim 2, wherein ξ ₀ is 30 (%). In the abrasive composition for polishing glass comprising abrasive particles,
The abrasive particles are
An aqueous medium dispersion of abrasive particles obtained by adding the abrasive particles to an aqueous medium is irradiated with ultrasonic waves, and the specific particle diameter α ₀ (μm) before the ultrasonic irradiation represented by the formula (1) The ratio (defined as the dispersion ratio (ξ)) of the above-mentioned particle abundance disappearing due to the ultrasonic irradiation action of the particles of α ₀ (μm) or more after ultrasonic irradiation is measured.
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle diameter α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
Abrasive composition for glass polishing, wherein abrasive particles having a dispersion ratio ξ measured by the method of formula (1) of a specific value ξ ₀ (%) or more are dispersed in an aqueous medium . The abrasive composition for polishing glass according to claim 4, wherein ξ ₀ is 30 (%). In the abrasive particles mainly composed of rare earth oxide containing cerium oxide, the amount of SO ₄ equivalent metal sulfate in the abrasive is 0.070 (mol / Kg) or less, and the abrasive Particles
An aqueous medium dispersion of abrasive particles obtained by adding the abrasive particles to an aqueous medium is irradiated with ultrasonic waves, and the specific particle diameter α ₀ (μm) before the ultrasonic irradiation represented by the formula (1) The ratio (defined as the dispersion ratio (ξ)) of the above-mentioned particle abundance disappearing due to the ultrasonic irradiation action of the particles of α ₀ (μm) or more after ultrasonic irradiation is measured.
ξ = [(V ₀ −V _t ) / V ₀ ] × 100 (%) (1)
(In the equation, V ₀ is the abundance (cumulative volume) of particles having a specific particle size α ₀ (μm) or more before ultrasonic irradiation, and V _t is the presence of particles having α ₀ (μm) or more after ultrasonic irradiation. Indicates the amount (cumulative volume).)
An abrasive particle for polishing highly dispersible glass, wherein the dispersion particle ξ measured by the method of formula (1) is an abrasive particle having a specific value ξ ₀ (%) or more. The abrasive particles for polishing highly dispersible glass according to claim 6, wherein ξ ₀ is 30 (%).   The abrasive particle according to claim 6 or 7, which contains a fluorine compound.   An abrasive composition for polishing glass comprising at least an aqueous medium and the abrasive particles according to any one of claims 6 to 8.   A glass polishing method using the glass polishing abrasive composition according to claim 9.