JP2012236273A - Polishing agent for polishing free abrasive grain and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive polishing agent for polishing free abrasive grains having high polishing speed for glass and imparting no damage to the glass caused by polishing.SOLUTION: The polishing agent for polishing free abrasive grains has an average secondary particle size of 1-3 μm, has no particles having the secondary particle diameters of 10 μm or larger, the secondary particle form of the polishing agent being spherical or equiaxial, and comprises MnOabrasive grains formed by firing granulated MnOat 800-1,000°C. The polishing agent for polishing free abrasive grains has high polishing speed for glass and imparts no damage to the glass caused by polishing, thus having excellent polishing performance for glass.

Description

  The present invention relates to a free abrasive polishing abrasive used for polishing liquid crystal panels, magnetic disks, optical glass, and the like, and a method for producing a free abrasive polishing abrasive.

  With the spread of liquid crystal televisions and computers, the amount of glass materials such as mother glass for liquid crystal panels, quartz glass for photomasks, and tempered glass for hard disks is increasing. Glass is also used for the optical lens. Since the surface of these glass materials needs to be mirror-finished or flattened, polishing is essential.

  In polishing glass materials, it is possible to obtain a large polishing rate by expressing not only mechanical polishing action but also chemical polishing action, and scratches such as scratches are hardly generated on the surface after polishing. Cerium oxide has been used.

  For example, in the polishing of quartz glass, which is a photomask substrate for liquid crystal, a polishing method is used in which a polishing pad made of urethane is attached to a polishing tool and a slurry in which cerium oxide abrasive grains are dispersed in water is supplied.

  Thus, cerium oxide is commonly used for polishing glass, but cerium oxide is an expensive rare earth oxide and its price is not stable, so there is a need for abrasive grains that can replace cerium oxide. It was done.

Inexpensive manganese oxide abrasive grains are known for chemical mechanical polishing (CMP) applications used for planarization of an interlayer insulating film on a semiconductor substrate. As the abrasive grains of manganese oxide, for example, a mass of MnO ₂ deposited on the anode by electrolyzing an electrolyte solution containing Mn ions is heated at 500 ° C. to 900 ° C., and the formed Mn ₂ O ₃ is pulverized. A method of using the particles as abrasive grains has been proposed (see, for example, Patent Document 1). However, when Mn ₂ O ₃ prepared by firing and pulverizing MnO ₂ is used as abrasive grains, there is a problem that the processing speed is lower than that of cerium oxide.

In addition, a method for producing abrasive grains by using Mn ₃ O ₄ as a manganese oxide source, heat-treating to Mn ₂ O ₃ and pulverizing or crushing the same is proposed (for example, see Patent Document 2). However, no consideration is given to scratches generated on the glass substrate surface.

Japanese Patent Laid-Open No. 10-60415 JP 2006-128395 A

  It is an object of the present invention to provide a free abrasive polishing abrasive that has an excellent polishing rate in polishing, has no scratches on the surface, and is economically advantageous, and a method for producing the free abrasive polishing abrasive. And

As a result of intensive studies, the inventor is Mn ₂ O ₃ abrasive grains obtained by firing granulated Mn ₃ O ₄ powder, and the average secondary particle diameter of the abrasive grains is 1 to 3 μm. Yes, the abrasive for polishing free abrasive grains, characterized by not containing the abrasive grains having a secondary particle diameter of 10 μm or more, has excellent polishing speed, and at the same time scratches the surface of the workpiece during polishing I found it not. Further, by setting the firing temperature of the Mn ₃ O ₄ powder to 800 ° C. to 1000 ° C., the specific surface area by the BET method of the abrasive grains becomes 4.0 m ² / g or less, and it is found that the polishing rate is particularly excellent. The invention has been completed. Furthermore, it discovered that the abrasive | polishing agent for grinding | polishing the free abrasive grains whose average primary particle diameter of the said abrasive grain is 0.5-2 micrometers is further excellent in polishing rate.

  The present invention is described in detail below.

The present invention is an Mn ₂ O ₃ abrasive obtained by firing granulated Mn ₃ O ₄ powder, wherein the average secondary particle diameter of the abrasive is 1 to 3 μm, and the secondary particle diameter is 10 μm or more. The abrasive for polishing free abrasive grains is characterized in that the abrasive grains are not contained. The loose abrasive grains are those in which individual abrasive particles are in a free state.

The abrasive for polishing free abrasive grains of the present invention comprises Mn ₂ O ₃ abrasive grains having an average secondary particle diameter of 1 to ₃ μm as main components and a dispersion medium. Examples of the dispersion medium include distilled water, ion exchange water, alcohol, and the like, but an aqueous system is preferable for handling. Moreover, a dispersing agent etc. can be added and pH adjustment can be performed to the abrasive | polishing agent for free abrasive grains of this invention as needed.

The Mn ₂ O ₃ abrasive grains having an average secondary particle diameter of 1 to ₃ μm as the main component are obtained by firing the granulated Mn ₃ O ₄ powder. By baking the granulated Mn ₃ O ₄ powder, the average secondary particle diameter becomes 1 to ₃ μm Mn ₂ O ₃ abrasive grains, and secondary particle diameters of 10 μm or more Mn ₂ O ₃ abrasive grains are hardly formed. .

The Mn ₂ O ₃ particles used as the abrasive grains have an average secondary particle diameter of 1 to 3 μm. This is because if the average secondary particle diameter is smaller than 1 μm, the polishing rate for glass is low, and if it is larger than 3 μm, scratches may occur on the surface of the workpiece during polishing. As a method for measuring the average secondary particle size, there are a laser diffraction method and an image analysis method using a scanning electron microscope.

The secondary particle shape of the Mn ₂ O ₃ abrasive is preferably spherical or equiaxed. When the shape is spherical or equiaxed, it is considered that the strength of the polishing powder is increased and a high polishing rate can be obtained. Moreover, since there are few sharp parts, it becomes difficult to generate | occur | produce a damage | wound on the surface of a workpiece at the time of grinding | polishing.

Moreover, it is more preferable that the average primary particle diameter of the Mn ₂ O ₃ abrasive grains as the main component of the abrasive for polishing free abrasive grains of the present invention is 0.5 to 2 μm. Since the average primary particle diameter of the Mn ₂ O ₃ abrasive grains is 0.5 to 2 μm, it is considered that the hardness of each grain of the abrasive grains is increased, and thus the polishing rate is further improved. As a method for measuring the average primary particle size, there is an image analysis method using a scanning electron microscope.

In addition, the abrasive for polishing free abrasive grains of the present invention is characterized by not containing Mn ₂ O ₃ abrasive grains having a secondary particle diameter of 10 μm or more. This is because if Mn ₂ O ₃ particles having a secondary particle diameter of 10 μm or more are present in the abrasive, scratches are likely to occur on the surface of the workpiece during polishing.

Incidentally, the free abrasive polishing polishing agent of the present invention preferably has a specific surface area by the BET method of _Mn 2 _{O 3} abrasive grains is less than 4.0 m ² / g. By setting the specific surface area to 4.0 m ² / g or less, pores are reduced inside the abrasive grains, the particle strength is improved, and the polishing rate is increased.

  Next, the manufacturing method of the abrasive | polishing agent for loose abrasive polishing of this invention is demonstrated.

The abrasive for polishing free abrasive grains of the present invention is obtained by granulating Mn ₃ O ₄ powder to 1 to 5 μm and then firing it to Mn ₂ O ₃ abrasive grains having an average secondary particle diameter of 1 to ₃ μm. was Mn ₂ O ₃ abrasive grains can a be produced by adding a dispersion medium.

The Mn ₃ O ₄ powder can be obtained by, for example, a method obtained by oxidizing manganese hydroxide produced by a hydrolysis reaction of metal manganese or a method of neutralizing and oxidizing a manganese sulfate salt with a basic aqueous solution. It is not limited to. As the size of the Mn ₃ O ₄ powder, those having a primary particle diameter of 0.05 to 3 μm and an average secondary particle diameter of 1 to 5 μm are preferable. When the average secondary particle size is smaller than 1 μm, the secondary particle size of Mn ₂ O ₃ after firing becomes small and the polishing rate becomes low. This is because if the average secondary particle diameter is larger than 5 μm, the secondary particle diameter of Mn ₂ O ₃ after firing becomes large and scratches are likely to occur on the surface of the workpiece during polishing. As a method for measuring the average secondary particle size, there are a laser diffraction method and an image analysis method using a scanning electron microscope.

First, Mn ₃ O ₄ powder is granulated to obtain granulated particles of Mn ₃ O ₄ having an average particle diameter of 1 to 5 μm. Examples of the granulation method include a method of slurrying Mn ₃ O ₄ powder and spray drying. When there is an agglomerated particle of Mn ₃ O ₄ during spray drying, it is preferable to perform ball milling or bead milling in advance. As the grinding media, ceramics such as alumina and zirconia are preferable because of high grinding efficiency.

In the case where Mn ₃ O ₄ powder having a small primary particle size is slurried and granulated by a spray drying method, the slurry is preferably spray dried in a state where the Mn ₃ O ₄ powder is well dispersed. Examples of the dispersion medium include ion exchange water, distilled water, alcohol and the like. By spray-drying the dispersed slurry, the constituent particles in the granulated powder are evenly arranged without unevenness, so that the particle size of the Mn ₂ O ₃ particles becomes uniform during subsequent firing. Examples of the method of dispersing the Mn ₃ O ₄ powder include a method of adjusting the pH of the slurry and adding a dispersant.

  The spray drying method is not particularly limited, but in order to produce granulated particles having an average particle size of 1 to 5 μm, a spray using an ultrasonic nozzle method or a multi-fluid nozzle that ejects slurry by compressed air. It is preferable to use a dryer. Examples of the multi-fluid nozzle for injecting slurry with compressed air include a two-fluid nozzle, a three-fluid nozzle, and a four-fluid nozzle.

The concentration of the Mn ₃ O ₄ slurry at the time of spray drying is preferably 2 to 50 wt%. If it is lower than 2 wt%, high-density granulated particles cannot be obtained, and if it is higher than 50 wt%, the slurry viscosity becomes high and spray drying cannot be performed. Increasing the slurry concentration increases the viscosity. In that case, an anionic, cationic, or nonionic dispersant may be added as appropriate to lower the viscosity.

Further, when the concentration of the Mn ₃ O ₄ slurry is 20 to 50 wt%, the granulated particles have a high density, so that sintering of each Mn ₃ O ₄ particle in the granulated particles is promoted during firing, and an average of 1 It becomes a Mn ₂ O ₃ abrasive grain having a secondary particle size of 0.5 to ₂ μm, and is more preferable.

It is preferable that the Mn ₃ O ₄ high-density granulated particles having an average particle diameter of 1 to 5 μm prepared by the spray drying method have a tap density of 1.0 to 1.3 g / cm ³ . When the tap density is lower than 1.0 g / cm ³ , the Mn ₃ O ₄ particles in the granulated particles are not close to each other and the promotion of sintering is small, and when the tap density is higher than 1.3 g / cm ^{3, the} primary When the particle diameter becomes large and it is used as an abrasive for polishing free abrasive grains, it causes scratches.

  For the tap density of the present invention, a commercially available tap density measuring device (SEITIN ENTERPRISE CO., LTD., KYT-2000) is used. Measured value.

Next, the granulated Mn ₃ O ₄ powder is fired to obtain Mn ₂ O ₃ particles. The firing temperature is preferably 800 to 1000 ° C. By setting the firing temperature to 800 to 1000 ° C., oxidation to Mn ₂ O ₃ is promoted, and at the same time, sintering in the granulated particles and secondary particles is promoted, the particle strength is improved, and the polishing rate is improved. . When the firing temperature is lower than 800 ° C., the particles are in a state of being necked with each other and are not sintered so much, so that there are many pores, so the strength of the particles is low and the polishing rate tends to be low.

As an atmosphere to be baked, an atmosphere to be oxidized, for example, an atmosphere in air, an air circulation atmosphere, or an oxygen gas circulation atmosphere can be given. A reducing atmosphere is not preferable because an oxidation reaction from Mn ₃ O ₄ to Mn ₂ O ₃ does not occur. Whether the constituent phase is Mn ₂ O ₃ can be confirmed by using an X-ray diffraction method or the like.

When the constituent phase is Mn ₂ O ₃ , the polishing rate for glass is improved. Not clear about this reason it is believed that some chemical interaction between the SiO ₂ and Mn is a constituent molecule of the glass is working.

As a method of firing the Mn ₃ O ₄ particles, in particular are not limited to, a box furnace or a tube furnace, is the use of a rotary kiln. In particular, a rotary kiln is preferred because it can prevent the temperature applied to the powder from being uniform and aggregation of secondary particles due to firing.

Since Mn ₂ O ₃ particles obtained by firing have a case where the particles are being aggregated, for the agglomerated particles and the average secondary particle diameter 1 to 3 [mu] m, the calcined Mn ₂ O ₃ particles Furthermore, it is preferable to grind and / or crush.

  Examples of the pulverization and / or pulverization method include a ball mill and a bead mill. As the grinding media, ceramics such as alumina and zirconia are preferable because of high grinding efficiency.

The secondary particle shape of the Mn ₂ O ₃ particles is preferably spherical or equiaxed. It is considered that when the shape is spherical or equiaxed, the strength of the Mn ₂ O ₃ particles is increased and a high polishing rate can be obtained. Moreover, since there are few sharp parts, it becomes difficult to generate | occur | produce a damage | wound on the surface of a workpiece at the time of grinding | polishing.

As a method for creating a spherical or equiaxed abrasive grains, resulting in Mn ₃ O ₄ to a powder of the slurry to spray drying or heat treating the Mn ₃ O ₄ powder was spherical by synthesis in liquid It is done. Moreover, when there exists aggregation of particles after heat processing, it is preferable to grind | pulverize.

In addition, the abrasive for polishing free abrasive grains of the present invention is characterized by the absence of Mn ₂ O ₃ particles having a secondary particle diameter of 10 μm or more. This is because if Mn ₂ O ₃ particles having a secondary particle diameter of 10 μm or more are present in the abrasive, scratches are likely to occur on the surface of the workpiece during polishing. After the Mn ₃ O ₄ powder was granulated 1 to 5 [mu] m, by performing the firing into _Mn 2 _{O 3} abrasive grains having an average secondary particle diameter 1 to 3 [mu] m, secondary particle diameter 10μm or more _Mn 2 _{O 3} particles Is hardly formed, but Mn ₂ O ₃ particles having a secondary particle diameter of 10 μm or more can be substantially eliminated by pulverizing and / or crushing the abrasive grains and classification with a cyclone in the liquid. .

  The abrasive for polishing free abrasive grains of the present invention has a sufficient polishing rate, and can be used for polishing various materials because it hardly causes scratches on the surface of the workpiece during polishing. It can be suitably used for glass materials such as mother glass, quartz glass for photomasks and tempered glass for hard disks.

  The abrasive for polishing free abrasive grains of the present invention has a sufficient polishing rate, and since it is difficult to cause scratches on the surface of the workpiece during polishing, it can be used for polishing various materials and is inexpensive. Can be manufactured.

Mn ₃ O ₄ is a diagram showing the abrasive grains of the X-ray diffraction pattern obtained by firing. SEM images of the abrasive grains produced by sintering a Mn ₃ O ₄ particles produced by an ultrasonic nozzle. The 45 wt% of high density slurry _Mn 3 _{O 4} particles prepared using a abrasive SEM image of produced by firing at 900 ° C..

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not restrict | limited to these Examples at all.

Example 1
As Mn ₃ O ₄ powder, Tono's Brownox (primary particle size 0.08 μm) was used. 950 g of ion-exchanged distilled water was added to 50 g of Mn ₃ O ₄ powder. A ball mill for 48 hours was performed using zirconia balls having a diameter of 10 mm to prepare a Mn ₃ O ₄ slurry.

The slurry is granulated and dried under the conditions of an inlet temperature of 200 ° C. and an air volume of 1.00 m ³ / min using a spray dryer (trade name “MDL-050M” manufactured by Fujisaki Electric Co., Ltd.) which is a four-fluid nozzle system. _{A 3} O ₄ granulated product was obtained. The average particle diameter (D50) measured by a particle size distribution meter (manufactured by Shimadzu Corporation, trade name “SALD-7100”) was 3.5 μm.

The Mn ₃ O ₄ granulated product was fired at 550 ° C. for 24 hours using a box-type electric furnace. The atmosphere for firing was air. The powder obtained by firing was identified by an X-ray diffractometer (trade name “RINT Ultimate 1III” manufactured by Rigaku Corporation), and confirmed to be a Mn ₂ O ₃ single phase.

An SC mill (trade name “SC150”, manufactured by Mitsui Mining Co., Ltd.) was used for the Mn ₂ O ₃ powder obtained by firing, and was wet-treated using ion-exchanged distilled water and φ1 mm zirconia beads as grinding media. A bead mill was performed. The grinding time was 10 minutes per kg of solid content. The obtained polishing slurry was measured with a particle size distribution diameter (manufactured by Shimadzu Corporation, trade name “SALD-7100”). As a result, the average secondary particle diameter was 2.3 μm, and there were no abrasive grains of 10 μm or more. Moreover, the BET specific surface area by the BET measuring apparatus (The product name "MONOSORB" by the Yuasa Ionics company) with respect to the abrasive grain which dried the slurry for grinding | polishing was 7.7 m < ² > / g.

(Example 2)
A Mn ₃ O ₄ granulated product was produced in the same manner as in Example 1, and baked at 700 ° C. for 24 hours using a box-type electric furnace. The atmosphere for firing was air. The constituent phase of the powder obtained by firing was identified by an X-ray diffractometer, and it was confirmed that it was a single phase of Mn ₂ O ₃ .

The Mn ₂ O ₃ powder obtained by firing was wet bead milled in the same manner as in Example 1 to obtain a polishing slurry. The average secondary particle diameter was 2.0 μm, and there were no abrasive grains of 10 μm or more. Further, the BET specific surface area was 5.8 m ² / g.

(Example 3)
A granulated Mn ₃ O ₄ product was produced in the same manner as in Example 1, and baked at 800 ° C. for 24 hours using a box-type electric furnace. The atmosphere for firing was air. The constituent phase of the powder obtained by firing was identified by an X-ray diffractometer, and it was confirmed that it was a single phase of Mn ₂ O ₃ .

The Mn ₂ O ₃ powder obtained by firing was wet bead milled in the same manner as in Example 1 to obtain a polishing slurry. The average secondary particle diameter was 1.4 μm, and there were no abrasive grains of 10 μm or more. The BET specific surface area was 4.0 m ² / g.

Example 4
A granulated Mn ₃ O ₄ product was produced in the same manner as in Example 1, and baked at 900 ° C. for 24 hours using a box-type electric furnace. The atmosphere for firing was air. The constituent phase of the powder obtained by firing was identified by an X-ray diffractometer, and it was confirmed that it was a single phase of Mn ₂ O ₃ . FIG. 1 shows an X-ray diffraction pattern of the fired powder.

The Mn ₂ O ₃ powder obtained by firing was wet bead milled in the same manner as in Example 1 to obtain a polishing slurry. The average secondary particle diameter was 1.0 μm, and there were no abrasive grains of 10 μm or more. The BET specific surface area was 1.6 m ² / g.

(Example 5)
As Mn ₃ O ₄ powder, Tono's Brownox (primary particle size 0.08 μm) was used. 980 g of ion-exchanged distilled water was added to 20 g of Mn ₃ O ₄ powder. A ball mill for 48 hours was performed using zirconia balls having a diameter of 10 mm to prepare a Mn ₃ O ₄ slurry.

The slurry is granulated and dried under the conditions of an inlet temperature of 120 ° C. and an air volume of 120 L / min using an ultrasonic nozzle type spray dryer (trade name “B90”, manufactured by Nihon Büch), and Mn ₃ O ₄ granulation is performed. I got a product. The average particle diameter (D50) measured from the SEM image of this powder was 1.0 μm.

The Mn ₃ O ₄ granulated product was fired at 900 ° C. for 24 hours using a box electric furnace. The atmosphere for firing was air. The constituent phase of the powder obtained by firing was identified by an X-ray diffractometer, and it was confirmed that it was a single phase of Mn ₂ O ₃ .

An SC mill was used for the Mn ₂ O ₃ powder obtained by firing, and wet bead milling was performed using ion-exchanged distilled water and φ1 mm zirconia beads as grinding media. The grinding time was 3 minutes per kg of solid content. The average secondary particle diameter measured from the SEM image of the powder obtained by drying the obtained polishing slurry was 1.0 μm, and there were no abrasive grains of 10 μm or more. FIG. 2 shows an SEM image of the powder that was fired at 900 ° C. and then pulverized. The shape was spherical. The BET specific surface area was 2.6 m ² / g.

(Example 6)
Tosoh Brownox was used as the Mn ₃ O ₄ powder. Distilled water ion-exchanged with Mn ₃ O ₄ powder was added so that the slurry concentration was 20 wt%, and Kao-made Poise 530 as anionic dispersant was added at 1.5 wt% with respect to the amount of Mn ₃ O ₄ powder. The resultant was added and ball milled to prepare a Mn ₃ O ₄ slurry. This slurry was spray-dried using the same apparatus and the same conditions as in Example 1 to obtain a Mn ₃ O ₄ granulated product. The average particle diameter (D50) measured by the same particle size distribution analyzer as in Example 1 was 4.1 μm.

The tap density of the granulated particles was measured and found to be 1.01 g / cm ³ .

The Mn ₃ O ₄ granulated product was baked at 900 ° C. for 8 hours using the same box-type electric furnace as in Example 1. The constituent phase of the powder obtained by firing was identified in the same manner as in Example 1, and it was confirmed that it was a single phase of Mn ₂ O ₃ .

  When the powder obtained by firing was observed with a scanning electron microscope, it was composed of particles having an average primary particle diameter of 0.7 μm.

A wet bead mill was performed on the Mn ₂ O ₃ powder obtained by firing in the same manner as in Example 1. When the obtained polishing slurry was measured by the same method as in Example 1, the average secondary particle size was 1.2 μm, and there were no abrasive grains of 10 μm or more. Further, the BET specific surface area was 1.5 m ² / g.

(Example 7)
Except that the slurry concentration was 30 wt%, spray drying was performed in the same manner as in Example 6, and the tap density of the granulated particles was measured and found to be 1.18 g / cm ³ . The obtained Mn ₃ O ₄ granulated product was fired under the same conditions as in Example 6. The constituent phase of the powder obtained by firing was identified by an X-ray diffractometer, and it was confirmed that it was a single phase of Mn ₂ O ₃ .

  When the powder obtained by firing was observed with a scanning electron microscope, it was composed of particles having an average primary particle diameter of 1.0 μm.

A wet bead mill was performed on the Mn ₂ O ₃ powder obtained by firing in the same manner as in Example 1. The average secondary particle diameter of the obtained polishing slurry measured by the same method as in Example 1 was 1.4 μm, and there were no abrasive grains of 10 μm or more. The BET specific surface area was 1.3 m ² / g.

(Example 8)
Spray drying was performed in the same manner as in Example 6 except that the slurry concentration was 45 wt%, and the tap density of the granulated particles was measured and found to be 1.24 g / cm ³ . The obtained Mn ₃ O ₄ granulated product was fired under the same conditions as in Example 6. The constituent phase of the powder obtained by firing was identified by an X-ray diffractometer, and it was confirmed that it was a single phase of Mn ₂ O ₃ .

  When the powder obtained by firing was observed with a scanning electron microscope, it was composed of particles having an average primary particle diameter of 1.2 μm.

A wet bead mill was performed on the Mn ₂ O ₃ powder obtained by firing in the same manner as in Example 1. The average secondary particle diameter of the obtained polishing slurry measured by the same method as in Example 1 was 1.4 μm, and there were no abrasive grains of 10 μm or more. FIG. 3 shows an SEM image of the powder that was fired at 900 ° C. and then pulverized. The BET specific surface area was 1.1 m ² / g.

(Comparative Example 1)
Without firing Tosoh's Brownox, ion-exchanged distilled water was added as it was as abrasive grains and adjusted to a concentration of 25% to obtain a polishing slurry.

(Comparative Example 2)
Tosoh Brownox was baked at 900 ° C. for 24 hours in an air atmosphere in a box-type electric furnace without spray drying. The atmosphere for firing was air. The constituent phase of the powder obtained by firing was identified by an X-ray diffractometer, and it was confirmed that it was a single phase of Mn ₂ O ₃ .

A wet ball mill using φ10 mm alumina balls was performed on the Mn ₂ O ₃ powder obtained by firing for 5 hours. The average secondary particle diameter according to the particle size distribution of the obtained polishing slurry was 5.2 μm, and abrasive grains of 10 μm or more were present. The BET specific surface area was 1.4 m ² / g.

(Polishing evaluation)
A quartz glass substrate of 800 mm × 920 mm was placed in a single-sided large polishing apparatus (trade name “SPL-1400R” manufactured by Okamoto Machine Tool Co., Ltd.), and the slurry of Examples 1 to 5 and Comparative Examples 1 and 2 obtained by the SC mill was used. On the other hand, ion-exchanged distilled water was added to adjust the concentration to 25% to obtain a polishing slurry. The slurry was used for 2 hours of free abrasive polishing. The polishing pad used was IC1000 manufactured by Nitta Haas, the polishing pressure was 0.1 MPa, and the rotation speed of the glass and the tool was 40 rpm.

  The processed glass substrate was evaluated for the polishing rate from the change in weight before and after polishing, and the presence or absence of scratches due to polishing from visual observation.

The results are shown in Table 1, and the polishing rate of the Mn ₂ O ₃ powder fired at each temperature of Examples 1 to 5 was 6 to 11 μm / h, and no visual scratch was observed. In particular, the polishing rate of the powder fired at 800 ° C. and 900 ° C. was high.

  In Comparative Example 1, the processing speed was slow. In Comparative Example 2, the polishing rate was as good as 10 μm / h, but there was a visual flaw.

実施例６〜８で作製したスラリーについても実施例１と同様の条件で研磨評価を行った。結果を表２に示すが、研磨速度は１１〜１２μｍ／ｈであり、目視による傷も確認されなかった。

Polishing evaluation was performed on the slurry prepared in Examples 6 to 8 under the same conditions as in Example 1. The results are shown in Table 2. The polishing rate was 11 to 12 μm / h, and no visual scratches were confirmed.

Claims (12)

Mn ₂ O ₃ abrasive grains obtained by firing granulated Mn ₃ O ₄ powder, wherein the abrasive grains have an average secondary particle diameter of 1 to 3 μm and a secondary particle diameter of 10 μm or more. An abrasive for polishing free abrasive grains, characterized in that it does not contain. ^{2. The} abrasive for polishing free abrasive grains according to claim 1, wherein a specific surface area of the abrasive grains by the BET method is 4.0 m ² / g or less.   3. The abrasive for polishing free abrasive grains according to claim 1, wherein an average primary particle diameter of the abrasive grains is 0.5 to 2 μm.   The abrasive for polishing free abrasive grains according to any one of claims 1 to 3, wherein the polishing object is glass. The Mn ₃ O ₄ powder is granulated to 1 to 5 μm and then fired into Mn ₂ O ₃ abrasive grains having an average secondary particle diameter of 1 to ₃ μm. A method for producing an abrasive for polishing free abrasive grains. The method for producing an abrasive for polishing free abrasive grains according to claim 5, wherein the Mn ₃ O ₄ powder is granulated by a spray drying method. The Mn ₃ O ₄ powder is granulated by a spray-drying method using a multi-fluid nozzle that jets slurry with an ultrasonic nozzle or compressed air, The abrasive for polishing a free abrasive according to claim 6, Method. The method for producing a polishing slurry for free abrasive grains according to claim 6 or 7, wherein the concentration of the Mn ₃ O ₄ slurry used in the spray drying method is 20 to 50 wt%. The polishing for free abrasive polishing according to any one of claims 6 to 8, wherein the tap density of the Mn ₃ O ₄ powder granulated by the spray drying method is 1.0 to 1.3 g / cm ^3. Manufacturing method.   The method for producing an abrasive for polishing free abrasive grains according to any one of claims 5 to 9, wherein the firing temperature is from 800C to 1000C. After calcination to Mn ₂ O ₃ abrasives, loose abrasive polishing abrasive according to any one of claims 5 to 10, characterized in that grinding and / or crushing the Mn ₂ O ₃ abrasives Manufacturing method. The method for producing an abrasive for polishing free abrasive grains according to any one of claims 5 to 11, wherein Mn ₂ O ₃ abrasive grains of 10 µm or more are removed by classification.

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