JP2018177576A - Method of producing irregularly shaped silica particles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that deformed silica particles having a large particle size cannot be obtained by a method of adding silicic acid to water glass to grow particles, and having a particle size and strength suitable as an abrasive. A method for producing irregularly shaped silica particles is provided. SOLUTION: A step of wet crushing porous silica gel under alkaline to make a crushed gel containing irregularly shaped silica particles a. A solution containing the crushed gel is heated by adding a silicic acid solution under alkaline. The deformed silica particles are characterized by having a step b of building up and filling the pores of the deformed silica particles by a reaction with silicic acid and growing the particles in the deformed state, and a step c of recovering the grown deformed silica particles. Manufacturing method. [Selection diagram] Fig. 2

Description

  The present invention relates to a method of producing irregularly shaped silica particles having a particle diameter and strength suitable for use as an abrasive.

  Abrasive grains of hard crystals such as diamond abrasive grains and α-alumina are used as high-speed abrasive grains for substrates such as Si wafers, glass HD and aluminum HD. However, although these hard abrasive grains have high grinding speed, they are irregularly shaped particles with a crushed surface, and it is often difficult to control the particle size distribution, so they often contain coarse particles, and deep scratches on the grinding surface As a result, a load is applied to the subsequent finishing and polishing process, which may eventually reduce the productivity.

  Therefore, if amorphous silica particles having a low hardness but no sharp fracture surface are used, an increase in the contact area to the polishing substrate due to the large primary diameter and the dynamic contact area due to the deformation ( An increase in the Feret diameter can be expected to have the effect of obtaining a high polishing rate.

  As a method of preparing irregularly shaped silica particles having a particle size suitable for abrasives, there has been known a method in which a siliceous liquid is added to irregularly shaped seed particles prepared from water glass or the like to make the particle size larger (patented) Literature 1).

Patent No. 5127452 gazette

  In hard disk and semiconductor manufacturing processes, polishing is applied to the manufacturing process to planarize the substrate. At the time of polishing, a so-called polishing slurry is used in which abrasive particles such as silica and ceria are dispersed in water and chemical components are added to control the polishing performance. In particular, abrasive grains are known to have a great effect on polishing performance, and performance required for abrasive grains includes high polishing speed and no defects such as scratches on the polishing surface.

  As a method to obtain a high polishing rate, it is general to use abrasive grains of large particle size, but when the particle size is too large, the number of particles decreases and the polishing rate decreases conversely, and the scratch also increases. Tend to Therefore, in order to obtain a high polishing rate without causing a scratch, a method of making the abrasive non-spherical is studied, and it is known that a high polishing rate can be obtained by using particles of an irregular shape.

  As a method of obtaining the irregularly shaped silica particles, a method of aggregating the silica particles at the time of nucleation using water glass as a raw material is known, but it was difficult to obtain irregularly shaped silica particles having a particle diameter of 100 nm or more by this method. In addition, silica particles with a particle diameter of 100 nm or less obtained by this method are used as seed particles, and a method in which a silica solution is added to make the particle diameter grow is as large as 200 nm or more. Since the seed particles grow spherically or nearly spherically when used, it has been difficult to grow the deformed seed particles as deformed to obtain relatively large deformed silica particles.

  In addition, although the inventors of the present invention examined a method for obtaining unusual-shaped silica particles by grinding wet silica or the like as another method for preparing unusual-shaped silica particles, although unusual-shaped silica particles were obtained, the wet process of gel structure In order to control the particle size and particle size distribution by crushing, the irregular-shaped silica particles made of silica have weak particle strength, and the obtained irregular-shaped silica particles also have weak particle strength, so when used as abrasive particles, The required polishing rate could not be obtained.

  In the present invention, silica gel is used as a seed particle, instead of a modified seed particle obtained from conventional water glass, using a particle composed of a modified porous gel obtained by crushing porous silica gel under specific conditions. In addition, a method for producing modified silica particles, in which the seed particles are grown, was studied. The particles composed of this irregularly shaped porous gel were obtained by wet disintegration of soft porous silica gel with a bead mill, for example, under alkaline conditions of pH 8.0 to 11.5 to an average particle size of 150 nm to 400 nm It has almost no coarse particles, has a relatively uniform particle size, and substantially retains the pore structure of the raw material porous silica gel.

  When particles made of such irregularly shaped porous gel are used as seed particles and the seed particles are grown in the coexistence of a silica solution, silica deposited on the silica surface preferentially fills the pores (recesses) of the seed particles. The seed particles can be grown in an irregular shape, and silica fills the pores inside the seed particles, thereby enhancing the particle strength of the resulting irregularly shaped silica particles. In addition, since the deformed porous gel with few coarse particles is used as the seed particles, the obtained deformed silica particles hardly contain coarse particles. It has been found that when this irregularly shaped silica particle is used as an abrasive particle, the polishing rate is relatively fast and the occurrence of scratches (striations) on the abrasive surface is significantly suppressed.

  The present invention is based on the above findings, using as a seed particle a particle composed of an irregularly shaped porous gel formed by crushing porous silica gel as a seed particle, and adding a silica solution to grow the seed particle using the method The present invention provides a method of efficiently producing irregularly shaped silica particles having a particle size and strength of suitable size. In the following description, the silica solution is deposited on the surface of the silica of the seed particle, and due to the difference in solubility, it preferentially reacts with pores that do not contribute to the particle size to fill the pores while the silica is dispersed on the particle outer surface. It is called build-up that particles grow by deposition of

The production method of the present invention is a method for producing a modified silica particle including the following steps a to c, and is a production method that solves the conventional problem by the configuration of the following steps a to c.
(Step a) A step of wet-disintegrating porous silica gel under alkaline conditions to give a solution containing particles composed of irregularly shaped porous gel
(Step b) A silica solution is added to a solution containing particles of the irregular shaped porous gel under alkaline conditions and heated, and the pores of the particles of the irregular shaped porous gel are filled with the reaction with the silica to form an irregular shape. Growing the particles as they are to form modified silica particles,
(Step c) A step of recovering the grown irregularly shaped silica particles.

Specifically, the production method of the present invention is
In step a, porous silica gel having a specific surface area of 300 to 800 m ² / g is converted to particles of an irregularly shaped porous gel having an average particle diameter of 150 to 400 nm,
In step b, the pores of the particles of the irregular shaped porous gel are filled with the reaction with the silica to make the specific surface area of the particles of the irregular shaped porous gel 100 m ² / g or less and the average particle diameter of 200 to 200 It is a method for producing the irregular shaped silica particles grown on the irregular shaped silica particles of 500 nm.

Moreover, specifically, the production method of the present invention is
In step a, the porous silica gel is wet disintegrated under alkaline conditions of pH 8.0 to 11.5 to form a solution containing particles composed of a modified porous gel. Coarse particles are preferentially broken at the same time as the progress of crushing is promoted by dissolving silica of the neck part between particles constituting porous silica gel by wet grinding under alkaline in the above pH range . In addition, since the crushed particles have a high pH of the solution, they are given a negative charge to be stabilized and reaggregation does not occur, so that generation of new coarse particles hardly occurs, so that the irregularly shaped porous hardly containing coarse particles It can be a solution containing particles consisting of gel.
In step b, the SiO ₂ concentration of the solution containing the particles of the irregular shaped porous gel is adjusted to 1 to 10% by mass, heated to 60 ° C. to 170 ° C., and alkaline under pH 9 to 12.5. Is added continuously or intermittently to fill the pores of the particles of the irregular shaped porous gel by reaction with silica to reduce the specific surface area of the particles and to grow the particles in an irregular manner.
In step c, the solution containing the grown heteromorphic silica particles is concentrated to recover the heteromorphic silica particles.

Furthermore, in the production method of the present invention, more specifically, in step b, the addition amount of the silicic acid solution is SiO ₂ mole of the silicic acid solution with respect to the SiO ₂ molar concentration of the solution containing particles composed of the irregular shaped porous gel. It is a manufacturing method of the said unusual shape silica particle which is a range which becomes 2 to 5 molar times concentration.

  Furthermore, the present invention includes a polishing abrasive dispersion containing the irregularly shaped silica particles obtained by any of the above-mentioned production methods.

  According to the production method of the present invention, a silica gel is wet-cracked under alkaline conditions to form a solution containing particles composed of an irregularly shaped porous gel, and particles composed of this irregularly shaped porous gel are used as seed particles to obtain a silica solution. When it is added, the silicic acid solution preferentially reacts with the pores of the seed particles and the particles grow while filling the pores, and the silicic acid liquid is consumed also in the reaction with the pores, so the seed particles remain in an irregular shape. Can grow large. Furthermore, the specific surface area is reduced and the strength of the particles is increased by filling the pores of the particles by reaction with silica. As a result, it is possible to obtain modified silica particles having a particle size and strength suitable as an abrasive.

  The irregular shaped silica particles obtained by the production method of the present invention have a particle diameter and strength suitable as an abrasive, and therefore when used as an abrasive, the polishing rate is fast and the abrasive grains stick to the substrate. The efficiency of the polishing operation can be significantly improved because the scratch is a grade that can be easily recovered in the secondary polishing step of the subsequent step.

SEM photograph of particles composed of the modified porous gel of Example 1 SEM photograph of the modified silica particles produced in Example 1

Hereinafter, the manufacturing method of the present invention will be specifically described.
The production method of the present invention comprises the steps of: (a) wet-disintegrating porous silica gel under alkaline conditions to form a solution containing particles composed of non-uniform porous gel; silica solution alkaline under a solution comprising particles consisting of non-uniform porous gel; The solution is added and warmed to build up the step of growing up the particles in the irregular shape into irregular silica particles b, filling the pores of the particles consisting of the irregular porous gel by reaction with the silica, and b. It is a method for producing irregularly shaped silica particles, comprising the step c of recovering the irregularly shaped silica particles.

[Step a]
The production method of the present invention uses porous silica gel as a starting material. By using the porous silica gel, the added silica reacts with the pores of the particles composed of the irregularly shaped porous gel, and the silica deposited on the outer surface of the particles promotes the growth of the particles while the pores are filled. By this buildup, the convexes on the outer surface of the particle contribute more to the increase in the outer diameter, and the recesses contribute less to the outer shape, so that the strength of the growing particles is increased and the deformation of the particles is suppressed. Large sized irregular shaped silica particles can be produced.

  The porous silica gel is preferably a gel that is easily broken up, and for example, a wet hydrogel obtained by washing a water glass gel or a gel by an alkoxide method is preferable. Since the gel according to the alkoxide method has less hydroxyl groups to be dehydrated and condensed, the dry powder is soft and a highly productive dry powder can be used. It is preferable that the particle size distribution of particles made of irregular shaped porous gel obtained by crushing porous silica gel be controlled within a certain range, and if it is a large gel lump that is hard to be broken, it takes time to be broken It is not preferable because the particle size distribution becomes wide.

  Parameters indicative of the porosity of porous silica gel include pore volume and specific surface area, and in the case of open pores, specific surface area and pore volume are approximately in proportion if the pore diameter is the same. . In the present invention, the specific surface area is used as a parameter indicating the porosity of the porous silica gel.

The porous silica gel preferably has a specific surface area in the range of 300 to 800 m ² / g. When the specific surface area is smaller than 300 m ² / g, the gel has few pores, so when silica solution is added to a solution containing particles composed of deformed porous gel obtained by crushing, from deformed porous gel Since the amount of silica which penetrates into the pores of the particles is small, the pores are difficult to be filled by the reaction with silica, and the added silicic acid solution is consumed so as to cause the particles to grow round and it becomes difficult to maintain the irregular shape. In addition, if the specific surface area is larger than 800 m ² / g, the strength is too weak, and even if the inside of the particle made of the irregular shaped porous gel obtained by crushing is built up by reaction with silica and partially filled, sufficient strength It is difficult to obtain unusual shaped silica particles of

The porous silica gel is crushed into particles of a non-uniform porous gel. Particles made of irregularly shaped porous gel are prepared by simultaneously deforming and crushing relatively soft silica gel having a specific surface area of about 300 to 800 m ² / g under strong shear such as a bead mill. For crushing, for example, it is preferable to use a sand mill crusher or bead mill containing glass medium. It is preferable to carry out crushing several times.

The variant of the particle can be assessed by the degree of variant. The degree of deformation is obtained by dividing the weight average particle size [nm] of the particles measured by the disk type centrifugal type particle size distribution measuring apparatus by the equivalent sphere equivalent particle size [nm] calculated from the specific surface area [m ² / g] of the particles. It is represented by The odd-shaped silica particles of the present invention preferably have a degree of deformation in the range of 1.5 to 10.0. The equivalent sphere-equivalent particle diameter (r) is calculated from the following equation using the specific surface area (SA) measured by the BET method and the particle density ()) [in the case of silica シ リ カ = 2.2]. . r = 6000 / (SA × ρ)

  In the present invention, the average particle size of particles composed of a non-uniform porous gel and the average particle size of non-uniform silica particles after particle growth mean the average particle size of the weight-reduced particle size distribution. (In the present application, the average particle size of the weight-converted particle size distribution is also referred to as “weight-average particle size”). The method of determining the average particle size of the weight conversion particle size distribution is described later.

  Usually, when pulverizing powder with a bead mill etc., the particle size of the powder decreases in proportion to the pulverizing time, but the soft thing with high surface area such as silica gel has a slow change in the particle size with respect to the pulverizing time It is broken into irregular shaped particles with a particle diameter of about 200 nm measured by light scattering method, and has a rough structure containing quite a lot of pores while maintaining the specific surface area before crushing . Therefore, even if this irregularly shaped silica particle is used as an abrasive as it is, it is easily broken due to lack of strength, and only a very low polishing rate can be obtained. Therefore, in the production method of the present invention, the silica solution is added to the solution containing the particles composed of the irregular shaped porous gel, and the pores inside the particles composed of the irregular shaped porous gel are built up with silica solution and filled up. I am strengthening the strength.

  Crushing of porous silica gel should be wet-cracking under alkalinity, and alkalinity is preferably in the range of pH 8.0 to 11.5. As the pH falls below the alkaline region, the negative potential gradually decreases, and becomes unstable in the neutral region to the acidic region, so that particles generated by the pulverization can not be present stably and are aggregated immediately. Further, if the pH is 11.5 or more, the dissolution of silica is promoted, which also causes aggregation, which is not preferable. The pH at the time of the wet disintegration is preferably in the range of 8.5 to 11.0.

  The average particle diameter of the particles composed of the irregular shaped porous gel is preferably in the range of 150 to 400 nm. If the average particle size of the particles is smaller than 150 nm, it is difficult to obtain a particle size having a size suitable for the abrasive, even if the silica liquid is added to grow the particles. In addition, when the average particle diameter of the particles made of the irregular shaped porous gel is larger than 400 nm, it is not preferable because the particle diameter suitable for the abrasive is exceeded. Furthermore, coarse particles having an average particle size of more than 400 nm are not preferable because they cause scratches. Centrifugation may be performed for the purpose of removing coarse particles contained in the irregularly shaped porous gel. The average particle size of the irregular shaped porous gel particles is preferably in the range of 160 to 350 nm.

  Crushing can be carried out in multiple steps with media of different sizes to suppress the spread of the particle size distribution of particles composed of the irregularly shaped porous gel. In addition, the adjustment of the particle size can also be controlled by changing the size of the medium.

[Step b]
Silica solution is added to a solution containing particles composed of irregularly shaped porous gel under alkaline condition and heated to fill pores in particles composed of irregularly shaped porous gel by reaction with silica and allow particles to grow while being irregularly shaped . The SiO ₂ concentration of the solution containing particles of the irregular shaped porous gel is preferably in the range of 1 to 10% by mass. If the concentration of SiO _{2 in the} solution containing particles made of the irregular shaped porous gel is less than 1% by mass, the efficiency of producing the obtained irregularly shaped silica particles is lowered. In addition, when the SiO 2 concentration is more than 10% by mass, the particle growth of the resulting irregularly shaped silica particles tends to be uneven, which is not preferable.
Moreover, the method of adding a silicic acid is also mentioned as another method of burying the pores of the irregular shaped porous gel while hydrothermally treating the irregular shaped porous gel. At the same time as filling the pores with the added silicic acid solution, part of the irregularly shaped porous gel dissolves and preferentially fills the pores.

  The heating temperature is preferably in the range of 60 ° C to 170 ° C. When the temperature is lower than 60 ° C., the growth of the particles composed of the irregular shaped porous gel is slowed, and when the temperature is higher than 170 ° C., the irregular shaped silica particles obtained tend to be spherical. The heating temperature is more preferably in the range of 60 ° C. to 100 ° C.

  The pH is preferably in the range of 9 to 12.5 when the silicic acid solution is added to a solution containing particles of an irregularly shaped porous gel. When the pH is less than 9, since the solubility of silica is low, the degree of supersaturation becomes extremely high, and the added silicic acid solution is not consumed by particle growth and easily formed as fine particles. In addition, since the negative potential is also lowered, the particles are easily aggregated, which is not preferable. If the pH is higher than 12.5, the dissolution of silica is promoted, which is not preferable.

  The solution containing the particles composed of the heteromorphic porous gel is adjusted in pH as needed. Although the adjustment means is not particularly limited, it is usually adjusted by adding an alkaline substance. Sodium hydroxide, water glass etc. can be mentioned as an example of such an alkaline substance. As a pH at the time of adding a silicic acid solution to the solution containing the particle which consists of irregular-shaped porous gel, the range of 9.5-12.0 is recommended suitably.

The addition amount of the silicic acid solution is in the range of SiO ₂ molar該珪acid liquid to SiO ₂ molar concentration of the solution containing the particles consisting of the profiled porous gel is 2 to 5 times by mole are preferable. When the addition amount of the silicic acid solution is less than the above range, the growth of the resulting irregularly shaped silica particles becomes insufficient, and the production efficiency of the irregularly shaped silica particles decreases. On the other hand, when the addition amount of the silicic acid solution is larger than the above range, the amount of unreacted silicic acid increases, which is not preferable. It is desirable to add the silicic acid solution continuously or intermittently.

The silicic acid penetrates into the interior of the particle through the pores of the particle composed of the irregularly shaped porous gel and builds up to reduce the specific surface area of the particle and increase the strength of the particle. The specific surface area of the particles consisting of irregular porous gel 100 m ² / g or less, it is desirable that preferably in the range of a specific surface area of 15m ² / g~50m ² / g. If the specific surface area of the irregular shaped porous gel particles is larger than 100 m ² / g, the strength of the obtained irregular shaped silica particles is insufficient, and when used as an abrasive, it tends to break down and the polishing rate tends to be slow.

  In addition, since the silicic acid solution is bonded to the surface of the particles of the irregularly shaped porous gel to grow the particles, it is possible to obtain irregularly shaped silica particles having a large particle diameter while maintaining the irregular shape. The particle diameter of the irregularly shaped silica particles after particle growth is preferably an average particle diameter of 200 to 500 nm.

[Step c]
The grown heteromorphic silica particles are recovered. Specifically, for example, the solution containing the grown unusual-shaped silica particles is cooled to about room temperature to 40 ° C., concentrated using an ultrafiltration membrane or the like, and further concentrated using an evaporator etc. You can recover the Centrifugation may be performed to remove coarser particles.

Hereinafter, examples of the present invention will be shown together with comparative examples. In Examples and Comparative Examples, the measurement of the specific surface area and the average particle size, and the polishing test were performed as follows.
[Measurement of specific surface area by nitrogen adsorption method]
Adjust the pH of the silica sol to 50 ml with HNO ₃ to 3.5, add 40 ml of 1-propanol, dry the sample at 110 ° C for 16 hours, grind it in a mortar and calcine it at 500 ° C for 1 hour in a muffle furnace It was used as a sample. Then, using a specific surface area measurement device (manufactured by Yuasa Ionics, model number Multisorb 12) and using a nitrogen adsorption method (BET method), the specific surface area was calculated from the amount of nitrogen adsorption by the BET one-point method.
In the specific surface area measurement device, 0.5 g of the sample after firing is taken in a measurement cell, and degassing treatment is performed at 300 ° C. for 20 minutes in a 30 v% nitrogen / 70 v% helium mixed gas flow, The temperature was maintained at liquid nitrogen temperature in the air stream, and nitrogen was equilibrated to the sample. Next, while flowing the mixed gas, the sample temperature was gradually raised to room temperature, the amount of nitrogen desorbed during that time was detected, and the specific surface area of the silica fine particles in the sample was calculated by a calibration curve prepared in advance.

[Measurement of average particle size]
A silica particle dispersion was diluted with a 0.5 mass% aqueous solution of sodium dodecyl sulfate to a solid content concentration of 2 mass%, and it was added to a disk centrifugal type particle size distribution measuring apparatus (model number: DC24000 UHR manufactured by US CPS instruments). .1 ml was injected by a syringe and measurement was performed in a density gradient solution of 8% to 24% sucrose at 18,000 rpm. The average particle size of the weight-reduced particle size distribution was used for the crushed product of the silica hydrogel (particles composed of the irregularly shaped porous gel). Moreover, it was set as the average particle diameter of weight conversion particle size distribution also about the unusual-form silica particle obtained by adding a silicic acid liquid to this crushed product, and building it up.

Polishing test
Substrate to be Polished As a substrate to be polished, a nickel-plated aluminum substrate for hard disks (a nickel-plated substrate manufactured by TOYO STEEL CO., LTD.) Was used. This substrate is a doughnut-shaped substrate (outer diameter 95 mmφ, inner diameter 25 mmφ, thickness 1.27 mm).
Polishing test Ion-exchanged water is added to large particle irregularly shaped silica particles with a concentration of 30% to make 344 g of a 9% dispersion, to which 5.65 g of 31% H 2 O 2 is added followed by pH with 10% nitric acid Was adjusted to 1.5 to prepare a polishing slurry.
The above-mentioned substrate to be polished is set in a polishing apparatus (manufactured by Nanofactor: NF300), and a polishing pad ("SUBA-800" manufactured by Nitta Haas Corporation) is used. The polishing was performed for 5 minutes while supplying the polishing slurry at a speed of 20 g / min at a rotation number of 60 rpm.
Polishing Rate The polishing rate was calculated from the weight difference between the polishing substrate before and after polishing and the polishing time.

Example 1
Preparation of Silica Hydrogel 462.5 g of sodium silicate is dissolved in water, and after adjusting a 24% by weight sodium silicate aqueous solution in terms of SiO ₂ , 25% by weight of sulfuric acid is added so that the pH is 4.5 and silica is obtained. A solution containing the hydrogel was obtained. This silica hydrogel solution is maintained at a temperature of 21 ° C. in a constant temperature bath, allowed to stand for 5.75 hours for aging, and then the content of sodium sulfate relative to silicon as SiO ₂ contained in the silica hydrogel is The purified silica hydrogel was obtained by washing with pure water to 0.05 wt%. The concentration of this purified silica hydrogel was 5 wt% in SiO ₂ content (concentration). The specific surface area was 600 m ² / g.
Disintegration <br/> of silica hydrogel was then placed a silica hydrogel 500g in 2L glass beaker, and adjusted to pH10 by the addition of 4.8 wt% NaOH aqueous solution. Into this, 1135 g of a glass medium of 0.25 mmφ was added and crushed using a sand mill crusher. Similarly, several batches were crushed to obtain 2000 g of 4% by weight of a crushed gel (a solution containing particles composed of a modified porous gel). The average particle size of the particles composed of the irregular shaped porous gel was 184 nm. The SEM image is shown in FIG. Next, 2716 g of a crushed gel (a solution containing particles composed of a modified porous gel) of which the silica concentration is adjusted to 2.76% by weight with ion-exchanged water is put in a 10 L separable flask and aqueous sodium hydroxide solution ( The pH was adjusted to 10.5 by adding 6.54 g of a concentration of 48% by mass). Subsequently, the temperature was raised to 98 ° C. and held for 30 minutes. Next, while keeping the temperature at 98 ° C., 5380 g of a 4.6% by weight silica solution was added over 20 hours, and then stirring was continued for another hour to obtain a preparation of silica particles. The pH of this preparation was 10.2. The mixed solution was cooled to about 40 ° C., and then the concentration of SiO _{2 was} concentrated to 12% by weight with an ultrafiltration membrane (SIP 1013 manufactured by Asahi Kasei Corp.).
Next, the SiO2 concentration was concentrated to 30% by weight with a rotary evaporator to recover large particle irregularly shaped silica particles. The average particle size of the irregularly shaped silica particles was 230 nm. The SEM image of this silica particle is shown in FIG. A polishing test was conducted on the irregularly shaped silica particles. The results are shown in Table 1.

Example 2
The pH was adjusted to 10 by adding 500 g of the silica gel obtained in Example 1 to a 2 L glass bottle and adding an aqueous 4.8 wt% NaOH solution. Into this, 2390 g of zirconia media of 1.0 mmφ was added and crushed using a sand mill crusher. Similarly, several batches were crushed to obtain 2000 g of 4% by weight of a crushed gel (a solution containing particles composed of a modified porous gel). Next, 1135 g of 0.25 mm diameter glass medium is added to 500 g of this crushed gel, and the second stage crushing is performed several batches, and 3.5% by weight of the crushed gel (a solution containing particles composed of irregularly shaped porous gel) 1900 g were obtained. The average particle diameter of the particles composed of the resulting irregularly shaped porous gel was 230 nm. The subsequent steps were carried out in the same manner as in Example 1, and the average particle diameter measurement and the polishing test were carried out on the obtained irregularly shaped silica particles. The results are shown in Table 1.

[Example 3]
The pH was adjusted to 10 by adding 500 g of the silica gel obtained in Example 1 to a 2 L glass bottle and adding an aqueous 4.8 wt% NaOH solution. Into this, 2390 g of zirconia media of 1.0 mmφ was added and crushed using a sand mill crusher. Similarly, several batches were crushed to obtain 2000 g of 4% by weight of a crushed gel (a solution containing particles composed of a modified porous gel). The average particle size of the particles composed of the irregular shaped porous gel was 298 nm. The subsequent steps were carried out in the same manner as in Example 1, and the average particle diameter measurement and the polishing test were carried out on the obtained irregularly shaped silica particles. The results are shown in Table 1.

Comparative Example 1
The crushed gel (a solution containing particles composed of an irregularly shaped porous gel) obtained in Example 1 was concentrated to a concentration of 9% by weight of SiO ₂ with an ultrafiltration membrane (SIP 1013 manufactured by Asahi Kasei Corp.). After that, a polishing test was conducted in the same manner as in Example 1 on the silica particles obtained without the buildup with the silicic acid solution. The results are shown in Table 1.

Comparative Example 2
In a 10 L separable flask, 2716 g of a crushed gel (a solution containing particles composed of a modified porous gel) of which the silica concentration is adjusted to 2.76% by weight with ion-exchanged water in Example 1 is placed in water with stirring. The pH was adjusted to 10.5 by adding 6.54 g of an aqueous solution of sodium oxide (concentration 48% by mass). Subsequently, the temperature was raised to 98 ° C. and held for 30 minutes. Then, while maintaining at 98 ° C., modified silica particles are produced in the same manner as in Example 1 except that 1304 g of a 4.6% by weight silica solution is added over 4.8 hours to adjust the pH to 10.4. Average particle size measurement and polishing test were conducted. The results are shown in Table 1.

Comparative Example 3
The silica hydrogel obtained in Example 1 is dried in a dryer at 100 ° C. overnight, then smashed in an agate mortar and calcined at 550 ° C. for 2 hours to obtain a solution containing particles of silica gel having a surface area of 200 m ² / g. Obtained. Although this was tried to be crushed under the same conditions as in Example 3, it could not be broken.

Claims (5)

A method for producing a modified silica particle comprising the following steps a to c.
(Step a) A step of wet-disintegrating porous silica gel under alkaline conditions to give a solution containing particles composed of irregularly shaped porous gel
(Step b) A silica solution is added to a solution containing particles of the irregular shaped porous gel under alkaline conditions and heated, and the pores of the particles of the irregular shaped porous gel are filled with the reaction with the silica to form an irregular shape. Growing the particles as they are to form modified silica particles,
(Step c) A step of recovering the grown irregularly shaped silica particles.
In step a, porous silica gel having a specific surface area of 300 to 800 m ² / g is converted to particles of an irregularly shaped porous gel having an average particle diameter of 150 to 400 nm,
In step b, the pores of the particles of the irregular shaped porous gel are filled with the reaction with the silica to make the specific surface area of the particles of the irregular shaped porous gel 100 m ² / g or less and the average particle diameter of 200 to 200 The method for producing irregularly shaped silica particles according to claim 1, wherein the irregularly shaped silica particles are grown to 500 nm.
In step a, the porous silica gel is wet-cracked under alkaline conditions of pH 8.0 to 11.5 to a solution containing particles consisting of a modified porous gel,
In step b, the SiO ₂ concentration of the solution containing the particles of the irregular shaped porous gel is adjusted to 1 to 10% by mass, heated to 60 ° C. to 170 ° C., and alkaline under pH 9 to 12.5. Continuously or intermittently, the pores of the particles comprising the irregular shaped porous gel are filled with the reaction with silica to reduce the specific surface area of the particles, and the particles are allowed to grow irregularly,
The method for producing irregularly shaped silica particles according to claim 1 or 2, wherein in step c the solution containing the grown irregularly shaped silica particles is concentrated to recover the irregularly shaped silica particles.
In step b, claim amount of silicic acid solution is in the range of SiO ₂ molar該珪acid liquid to SiO ₂ molar concentration of the solution containing the particles consisting of irregular porous gel is 2 to 5 times by mole The manufacturing method of the irregular-shaped silica particle as described in any one of Claims 1-3.
The abrasive-abrasive grain dispersion liquid containing the unusual-form silica particle obtained by the manufacturing method of the unusual-form silica particle as described in any one of Claims 1-4.