JP3410522B2 - Method for producing granular amorphous silica - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing granular amorphous silica, and more particularly to a method for directly producing granular amorphous silica in the neutralization process of alkali silicate acid.

[0002]

2. Description of the Related Art So-called dry process silica and wet process silica are known as amorphous silica-based fillers, and by utilizing their characteristics, paints, information recording papers, rubbers, Used for applications such as resin moldings. The former silica is obtained by decomposing SiCl ₄ in an oxygen-hydrogen flame, has a fine particle size and a spherical shape, and has a relatively small surface activity based on the specific surface area, pore volume, pore distribution, etc. . On the other hand, the latter silica is obtained by neutralizing alkali silicate with an acid, and generally has a large particle size and a wide particle size distribution, but its inside is porous and its surface activity is relatively large. As described above, the amorphous silica has greatly different physical properties depending on its production method, and particularly the latter wet method is such that the concentration, temperature, and the reaction conditions for neutralizing alkali silicate with acid
Since various conditions such as pressure, time and reaction method can be changed, amorphous silica having widely different properties can be obtained.

Among these amorphous silica type fillers,
Demand for regular amorphous silica particles such as fine spherical silica particles is increasing because they have no cohesiveness among filler particles and are excellent in dispersibility in resins and the like.

Conventionally, as a method of producing fine spherical silica particles, a method of hydrolyzing an organic silane in an organic solvent such as ethanol, a method of forming a silica sol or a gel into a spherical shape, and a W / alkali silicate aqueous solution and an organic solvent are used. Known methods include preparing an O emulsion and then hydrolyzing it, forming fused silica into spheres, and treating fixed zeolite particles with an acid. However, there were problems such as high raw material costs, and it was not possible to sufficiently meet the above-mentioned demand.

More recently, US Pat. No. 4,752,458
In the specification, an acid solution is added to a solution of soluble silicic acid, and an organic polymer solution consisting of alginic acid alkali metal salt, alginic acid ammonium salt, starch, gelatin, pectin or a mixture thereof is added prior to forming a gel. A method of making microspherical silica consisting of adding is described.

[0006]

The above-mentioned prior art is excellent in the idea of directly producing fine spherical particles by adding a water-soluble polymer in the neutralization process of an alkali silicate with an acid. The yield of fine spherical particles obtained by the addition of a water-soluble polymer is as low as about 40% or less, and even if the yield is relatively high, the particles are non-spherical particles with irregular shapes and particle sizes, and the filterability is extremely high. Poor practicality.

When the amorphous silica nucleating agent and a water-soluble polymer coexist in the neutralization process of an alkali silicate solution with an acid, the present inventors yielded fine spherical particles of a partially neutralized alkali silicate product. It has been found that the particles are well and evenly precipitated.

That is, an object of the present invention is to provide a method for producing spherical amorphous silica capable of precipitating fine spherical silica in high yield in the neutralization process of alkali silicate with an acid. Another object of the present invention is to provide a method capable of inexpensively producing a regular granular amorphous silica having a regular particle shape of spherical or nearly spherical and having a uniform particle size distribution.

[0009]

According to the present invention, an alkali silicate aqueous solution, an amorphous silica nucleating agent, a water-soluble organic polymer and a partially neutralized acid aqueous solution are mixed and the mixture is left to stand. There is provided a method for producing granular amorphous silica, which comprises producing a granular material comprising a partially neutralized product of alkali silicate, separating the granular material, and neutralizing with an acid.

[0010]

In the present invention, when a combination of an amorphous silica nucleating agent and a water-soluble organic polymer is allowed to coexist in the partial neutralization of alkali silicate, the partially neutralized product of alkali silicate is formed in a good yield and in a fixed form. It is based on the discovery that it grows into spherical granules. "Table 1" to "Table 4" to be described later are based on the sodium silicate aqueous solution, the amorphous silica nucleating agent, various water-soluble polymer solutions, and the partially neutralized amount of sulfuric acid. To prepare a transparent mixed solution, and add this mixed solution to 20
The results of measuring the yield (based on SiO ₂ ) of the partially neutralized alkali silicate precipitates when left at 14 ° C. for 14 hours and the particle shape and particle size of the granules are shown.

According to the results of "Table 4", even if various water-soluble organic polymers are added, when the amount of the nucleating agent added is zero, the aggregate growth product of the partially neutralized alkali silicate product. The high yield of 70% is 30% of the low yield, and the relatively high yield has extremely poor filterability, and the particle shape and particle size are not uniform.
It is clear that when an amorphous silica nucleating agent is added at the same time, the yield is as high as 90% or more, and the particle shape and particle diameter are almost constant.

The attached drawing "FIG. 1" is a scanning electron micrograph (magnification: 10000) showing the particle structure of the granular amorphous silica according to the present invention, and the particles have a substantially spherical uniform particle shape. It is understood that. Further, “FIG. 2” and “FIG. 3” are volume-based and number-based particle size distribution curves of the granular amorphous silica according to the present invention, respectively. From these graphs, it is understood that the granular amorphous silica according to the present invention has a uniform particle size distribution close to monodispersion.

Generally, the degree of uniformity of particle size (particle size) is
It can be evaluated by the ratio (D ₂₅ / D ₇₅ ) of the particle size corresponding to the integrated value 25% in the integrated particle size distribution curve (D ₂₅ ) and the particle size corresponding to the integrated value 75% in the same curve (D ₇₅ ). That is, the smaller this value, the narrower the particle size distribution, and the larger this value, the wider the particle size distribution.
The particulate amorphous silica according to the present invention has a feature that the ratio of D ₂₅ / D ₇₅ is 2.0 or less, particularly 1.6 or less in the volume-based distribution, and the particle size is uniform.

Further, sphericity in spherical particles, the major axis of the particle cross section (Torukagemen) (D _L) and minor axis (D _S)
The ratio (D _S / D _L ) can be evaluated. Particulate amorphous silica according to the present invention, the sphericity (D _S / D _L) of 0.90
80% or more of the total is in the range of 1.00 to 1.00, which is remarkably excellent. In the present invention, in the partial neutralization of the alkali silicate, the coexistence of the amorphous silica nucleating agent and the water-soluble organic polymer causes the fact that aggregation growth into spherical particles having a fixed shape occurs. It was discovered as a phenomenon from experimental facts, and its theoretical basis has not been clarified yet, but it is considered as follows.

That is, in the system of the present invention, the alkali silicate partially neutralized product is precipitated and grown on the surface of the amorphous silica nucleating agent, and the water-soluble organic polymer is precipitated particles of the alkali silicate partially neutralized product. It is recognized that they are spherically aggregated when dispersed in water. In other words, the water-soluble organic polymer has both an action as a flocculating agent and an action as a dispersion stabilizer, and the amorphous silica nucleating agent has a function of trapping a partially neutralized sodium silicate product on the surface. Have This is the reason why the partial neutralization product of sodium silicate coagulates and grows into regular spherical particles having a narrow particle size distribution and the yield thereof is improved by the combined use of both.

[0016]

Preferred Embodiment of the Invention

(Alkali silicate) As an alkali silicate, m is a number of 1 to 4, particularly 2.5 to 3.5 in the formula "Chemical formula 1" Na ₂ O.mSiO ₂ formula. An aqueous solution of an alkali silicate having the composition of, especially sodium silicate, is used.

The composition of the alkali silicate is related to the stability of the mixed solution and the yield and particle size of the formed particles. When the molar ratio (m) of SiO ₂ is smaller than the above range, precipitation of partially neutralized particles becomes difficult to occur, yield tends to decrease, particle shape and particle morphology are likely to be uneven, and a large amount is required for partial neutralization. This is not preferable because it requires the above acid. On the other hand, S
If the molar ratio of iO ₂ is larger than the above range, the stability of the mixed solution is lowered and the particle morphology deviates from the true spherical shape, and the particle size distribution is not sharp. The concentration of alkali silicate is SiO ₂ in the mixed solution.
It is preferable to set the concentration as 3 to 9% by weight, particularly 5 to 8% by weight.

(Amorphous Silica Nucleating Agent) As the amorphous silica nucleating agent, any silica sol, as long as the particle size is fine,
Silica gel or anhydrous silica powder is used. Submicron particles having a particle size of 1 μm or less are preferable.
As a suitable example of the silica sol, Snowtex (manufactured by Nissan Kagaku Co., Ltd.) Liudox or the like is preferably used.
An acidic silica sol obtained by treating an alkali silicate with a mineral acid can also be used.

Aerosil (manufactured by Nippon Aerosil Co., Ltd.), fumed silica (manufactured by WR Grace), etc. are preferably used as the silica sol or anhydrous silica powder having a fine particle size. These dry process silicas have a fine primary particle size, but they are aggregated into fairly large secondary particles, so it is important to use wet pulverization and use as a slurry having a dispersed particle size of 1 μm or less. is there. Silica obtained by hydrolyzing an organic silane is suitable for the purpose of the present invention because it has a fine primary particle size and few agglomerated particles.

(Water-soluble organic polymer) As the water-soluble organic polymer, anionic or nonionic water-soluble organic polymer is used. Examples of the anionic polymer include sodium polyacrylate or a copolymer of sodium polyacrylate and polyacrylamide, sodium polymethacrylate, sodium alginate, ammonium alginate, carboxymethyl starch.
Powders, acrylamide-acrylic acid copolymers , maleic anhydride-vinyl ether copolymers, chitosan, sodium styrenesulfonate copolymers and the like are used. Examples of the nonionic polymer include polyacrylamide, polyvinyl alcohol (PVA), starch, cyanated starch, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, veegum, gelatin, polyethylene glycol and the like.

These water-soluble polymers can be used alone or in combination of two or more. It was found that there is a close relationship between the anionic property of the water-soluble organic polymer used in the present invention and the particle size of the final granules. In general, the larger the anionic property, the smaller the particle size of the final granules, and the one having a small anionic property or the nonionic product produces a large particle size. The anionic property of the water-soluble organic polymer is such that the concentration (mmole number) of the acid group (carboxyl group) per 100 g of the water-soluble polymer is 0 to 1070 m.
It is an advantage of the present invention that granules of any particle size can be obtained by varying in the range of eg / 100g.

As the (acid) acid, various inorganic acids and organic acids are used. From the economical point of view, it is preferable to use mineral acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid. However, sulfuric acid is the most excellent in terms of the yield of granules and the uniformity of particle size and morphology. In order to carry out a homogeneous reaction, it is preferable to use it in the form of a dilute aqueous solution, and it is generally preferable to use it at a concentration of 1 to 15% by weight. If necessary, NaCl,
A small amount of neutral salts such as Na ₂ SO ₄ and Na ₂ CO ₃ may be added.

(Production of Granules) In the present invention, when the stock solution for precipitating the granules is prepared, the order of addition of the respective raw material components is not particularly limited, but the alkali silicate is diluted with water and then partially neutralized. It is desirable to add a certain amount of acid and then mix with the amorphous silica nucleating agent, and to thoroughly mix the water-soluble organic polymer with this mixture in the form of an aqueous solution. The amorphous silica nucleating agent is preferably added in an amount of 1 to 80% by weight, particularly 2 to 60% by weight, based on the total SiO ₂ , and if the amount is less than the above range, the yield of final granules tends to decrease. If there is more than the above range, the particle strength of the granular material is reduced,
The particle size distribution of particles tends to be broad.

The water-soluble organic polymer is preferably added in an amount of 5 to 100% by weight, particularly 10 to 50% by weight, based on SiO ₂ , and when the amount is less than the above range, the precipitation yield of the particulate matter is decreased. However, there is no particular merit even if it is used in a larger amount than the above amount, and it is rather disadvantageous economically. The amount of acid used during mixing is such that a homogenous mixed solution (clear) is produced by partial neutralization, and the pH of the mixed solution is 10.2 to 11.2, particularly 10.3 to 10 It is preferable to use it in an amount so that it becomes 0.8. After thoroughly mixing and homogenizing each component, the mixed solution is allowed to stand to precipitate the partially neutralized granular material.

The deposition conditions are generally 1 to 10
It is suitable to leave it at a temperature of 0 ° C. for about 1 to 50 hours.
Generally, the lower the temperature, the larger the particle size of the deposited particles, and the higher the temperature, the smaller the particle size of the deposited particles. Thus, it is one of the advantages of the present invention that the particles can be controlled by controlling the temperature. The precipitated particles are separated from the mother liquor, and the dispersed particles are neutralized by adding an acid, and then washed with water, dried, classified and the like to obtain a product. Since the separated mother liquor and the separated liquid after neutralization contain unprecipitated silica content and water-soluble polymer, these can be effectively used for the next mixed precipitation.

(Granular Amorphous Silica) The granular amorphous silica according to the present invention has a BET specific surface area of 1 as described above.
Amorphous silica having a particle size in the range of 0.3 to 50 μm, the particles having a clear spherical shape, and having a major axis (D ₁ ) and a minor axis (D) of 00 to 800 m ² / g. _s )
Sphericity expressed by the ratio (D _S / D _L ) of 0.90 to 1.
00 particles are 80% or more, the formula

## EQU1 ## In the formula D ₂₅ / D ₇₅ , D ₂₅ represents the particle size of 25% value of the volume-based cumulative particle size distribution curve by the Coulter Counter method, and D ₇₅ represents the particle size of the 75% value. It has a novel combination characteristic characterized in that the sharpness of the particle size distribution defined by is 1.2 to 2.0 and the refractive index is in the range of 1.44 to 1.48.

The granular amorphous silica is made of metal soap, resin acid soap, various resins or waxes, silane compounds,
If desired, an alumina-based, titanium-based, zirconia-based coupling agent, oxides or hydroxides of various metals, silica coating, or the like can be applied.

Utilizing these characteristics, various thermoplastic resins, for example, propylene homopolymer as a crystalline propylene polymer, or ethylene-propylene copolymer,
Low-, medium-, high-density or linear low-density polyethylene, ionic cross-linked olefin copolymers, ethylene-vinyl acetate copolymers, olefin resins such as ethylene-acrylic acid ester copolymers, polyethylene terephthalate,
Blended with thermoplastic polyesters such as polybutylene terephthalate, polyamide resins such as 6-nylon, 6.6-nylon and 6.8-nylon, chlorine-containing resins such as vinyl chloride and vinylidene chloride, polycarbonate, polysulfones and the like. It can be used for imparting slip properties and anti-blocking properties to resin molded products such as various stretched, non-stretched and blown films formed by the above. To this end, the amorphous silica according to the present invention comprises 0.01 to 10 parts by weight per 100 parts by weight of the thermoplastic resin,
In particular, it can be added in an amount of 0.02 to 2 parts by weight.

Furthermore, the amorphous silica according to the present invention comprises
Can be used in various applications by blending with various paints, extender pigments for inks, adhesives, coating resin compositions, and as a carrier or filler for pharmaceuticals, foods, agricultural chemicals, insecticides, etc. Specifically, toner fluidity improver, high-grade abrasive, matte filler, chromatographic carrier, perfume carrier, putty filler, adsorbent, fluidity improver,
It can be used as a release agent, rubber filler, ceramics base, powder foundation, paste foundation, baby powder, cosmetic base such as cream antiperspirant, and the like. The invention is illustrated in the following examples.

[0030]

The present invention will be described in detail by the following examples. The measurement of the powder physical properties of the amorphous spherical silica and the evaluation test were carried out by the following methods.

(1) Particle size Coulter counter (TA-II manufactured by Coulter Electronics Co., Ltd.) was used to measure with an aperture tube of 50 μm. (2) Particle size by SEM Particle size Scanning electron microscope (Hitachi S-570) Obtained from a photographic image, representative particles were selected, and the diameter of the particle image was measured using a scale and shown as the primary particle size. It was (3) Representative particles were selected from the photographic images obtained with a sphericity scanning electron microscope (Hitachi S-570), and the major axis and minor axis of the particle image were measured using a scale to obtain the following formula. I asked from.

[Number 2] sphericity = short diameter (D _S) / long diameter (D _L) × 100

(4) Refractive Index Using a Abbe refractometer, a solvent of known refractive index (α
-Bromnaphthalene, kerosene). Then L
According to Arsen's oil immersion method, a few mg of the sample powder is taken on a slide glass, 1 drop of a solvent having a known refractive index is added, a cover glass is put, and the movement of the Becke line is observed by an optical microscope to obtain the value. (5) Specific surface area and pore volume Sorptomatic Series manufactured by Carlo Erba
s 1800 was used and measured by the BET method.

(6) Yield After measuring the weight of the obtained dried product, it was converted into anhydride (860 ° C.).
It is determined by the loss on ignition) and then divided by the amount of SiO ₂ obtained from the analytical value in the charged sodium silicate.

## EQU3 ## Yield (%) = anhydride weight (g) / input SiO ₂
Quantity (g) × 100 (7) Chemical composition It was measured according to JIS M-8852 silica analysis.

Example 1 No. 3 sodium silicate (SiO ₂ component 22.3%, Na ₂ O) was added to a 2 L stainless beaker.
Ingredients (7.0%) were weighed at 439 g (7% as the SiO ₂ concentration in the total amount of liquid), 471 ml of pure water was added, and then 400 g of 5 wt% sulfuric acid was added while stirring with a high stirrer.
Was adjusted to 10.5 and kept at 20 ° C. in a constant temperature bath. With further stirring, 210 g of silica sol (Snowtex C) (SiO
₍₂ ) (30% addition) was added slowly so as not to cause cloudiness, and 450 g of a 4 wt% solution of sodium alginate, which is a weak anionic polymer, was added and dispersed, and then stirring was stopped and the mixture was allowed to stand at that temperature for 15 hours. . PH at the start of standing
Was 10.4. After standing for 15 hours, the precipitate and mother liquor were separated by filtration, the obtained cake was redispersed in pure water, and 5% sulfuric acid was added until the pH became 3.0, and when the pH was almost stable at 3.0, The mixture was stirred for 1 hour as it was, filtered, washed with water, further dried overnight in a thermostatic dryer at 110 ° C., pulverized with a sample mill, and further calcined at 500 ° C. for 2 hours to obtain fine spherical silica powder. The properties of this powder are shown in Table 1, an electron micrograph (SEM) is shown in FIG. 1, and a particle size distribution diagram by the Coulter counter method is shown in FIG. 2 (volume basis) and FIG. 3 (number basis).

Example 2 A polyacrylamide (10% solution, molecular weight of about 500,000) which is a nonionic polymer flocculant was used in place of the sodium alginate of Example 1 except that the standing time was 48 hours. A fine spherical silica powder was prepared in the same manner as in Example 1. Table 1 shows the properties of this powder.
An electron micrograph (SEM) is shown in FIG.

(Examples 3 to 4) Instead of the sodium alginate of Example 1, polyacrylamide (10% solution, molecular weight about 500,000, anionization degree 10%) or esterified starch (which is an anionic polymer flocculant) was used. 7% solution MS # 5300 manufactured by Nippon Food Processing Co., Ltd., and allowed to stand for 1 hour.
A fine spherical silica powder was prepared in the same manner as in Example 1 except that the time was 2 hours. The properties of this powder are shown in Table 1.

(Examples 5 to 7) Microspherical silica powder was prepared in the same manner as in Example 4 except that the amount of silica sol in Example 3 was changed to 5, 50 and 70% as SiO ₂ . The properties of this powder are shown in Table 1.

[0038]

[Table 1]

(Examples 8 to 10) A fine spherical silica powder was prepared in the same manner as in Example 1 except that a 5% solution of Na ₂ CO ₃ , NaCl and Na ₂ SO ₄ was added instead of water. did. The properties of this powder are shown in Table 2.

(Example 11) In Example 1, the amount of a 4 wt% solution of sodium alginate (a reagent manufactured by Wako Pure Chemical Industries, Ltd.) was changed to 300.
A fine spherical silica powder was prepared in the same manner as in Example 1 except that 150 g of polyacrylamide (10% solution, molecular weight: about 500,000) as an anionic polymer flocculant was added. The properties of this powder are shown in Table 2.

(Example 12) A 5% solution of esterified starch in Example 4 was added to 400 g, and polyacrylamide (10%) as an anionic polymer flocculant was used.
Example 4 except that 50 g of a solution having a molecular weight of about 500,000 was added.
A fine spherical silica powder was prepared in the same manner as in. The properties of this powder are shown in Table 2.

[0042]

[Table 2]

(Examples 13 to 16) The amount of polyacrylamide (10% solution, molecular weight about 500,000), which is an anionic polymer flocculant in Example 3, was set to 350 g, and further 4% P was added.
Microspherical silica as in Example 3 except that 100 g of each of VA (PVA-117 manufactured by Kuraray Co., Ltd.) solution, 5% gelatin solution, liquid polyethylene glycol, and 5% starch (MS-4600 manufactured by Nippon Food Processing Co.) was added. A powder was prepared.
The properties of this powder are shown in Table 3.

(Examples 17 to 18) Instead of the silica sol (Snowtex C) in Example 1, silica hydrogel was wet-milled with a ball mill to obtain a slurry (SiO ₂ concentration 2).
0%, average particle size 0.88 μm) or finely divided as in Example 1 except that a slurry obtained by wet pulverizing Aerosil similarly to silica hydrogel slurry (SiO ₂ concentration 20%, average particle size 0.81 μm) was used. A spherical silica powder was prepared. The properties of this powder are shown in Table 3.

[0045]

[Table 3]

(Comparative Examples 1 and 2) Powder properties in the case where all were prepared by using sodium silicate without adding silica sol as a nucleating agent in Examples 1 and 4, and Table 4 shows electron micrographs (SEM). 5 shows.

(Comparative Example 3) The properties of the powder prepared in the same manner as in Example 4 except that the amount of silica sol in Example 4 was changed to 90% by SiO ₂ are shown in Table 4 as an electron micrograph (SEM).
Is shown in FIG.

[0048]

[Table 4]

(Comparative Example 4) A comparative example 4 was prepared in the same manner as in Example 1 except that the amount of sodium alginate was changed to 4% based on SiO ₂ (98 g of 4% sodium alginate solution and 352 g of pure water were added). However, spherical particles were not obtained.

(Comparative Example 5) Example 5 except that an acrylamide-modified cationic polymer flocculant was used in place of the polyacrylamide (10% solution, molecular weight about 500,000) which is an anionic polymer flocculant in Comparative Example 5. It was prepared in the same manner as in Example 4, but could not be prepared into spherical particles.

[0051]

INDUSTRIAL APPLICABILITY According to the present invention, in the neutralization process of an alkali silicate solution with an acid, coexistence of amorphous silica and a water-soluble organic polymer allows granular amorphous silica to be produced at a high yield. The obtained granular amorphous silica is
An amorphous silica the BET specific surface area is 100 to 800 m ² / g, the entire clear spherical particles, and the particles of the long diameter (D _L) and a ratio of minor axis (D _s) (D _S / D _l )
Amorphous particles having a sphericity of 0.90 to 1.00 and a sharp particle size distribution of 80% or more, and a refractive index of 1.44 to 1.48 Silica spherical particles could be provided.

[Brief description of drawings]

1 is a scanning electron micrograph (10000 ×) showing the particle structure of granular amorphous silica according to Example 1 of the present invention.

FIG. 2 is a volume-based particle size distribution curve of granular amorphous silica according to Example 1 of the present invention.

FIG. 3 is a number-based particle size distribution curve of granular amorphous silica according to Example 1 of the present invention.

FIG. 4 is a scanning electron micrograph (10000 ×) showing a particle structure of granular amorphous silica according to Example 2 of the present invention.

FIG. 5 shows a structure of the silica powder obtained in Comparative Example 1100.
It is a scanning electron micrograph at 00 times.

FIG. 6 is a diagram showing the structure of the silica powder obtained in Comparative Example 3100.
It is a scanning electron micrograph at 00 times.

Continuation of the front page (56) Reference JP-A-5-193927 (JP, A) JP-A-60-204614 (JP, A) JP-A-62-36015 (JP, A) JP-A-62-153112 (JP , A) JP-B-50-24275 (JP, B1) JP-A-62-503097 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C01B 33/00-33/193 JISST File (JOIS) WPI (DIALOG)

Claims (9)

(57) [Claims] 1. An alkali silicate aqueous solution, an amorphous silica nucleating agent, a water-soluble organic polymer, and a partially neutralized amount of an acid aqueous solution are mixed, and the mixture is allowed to stand to remove the alkali silicate partially neutralized product. And then separating the granules,
A method for producing granular amorphous silica, which comprises neutralizing with an acid. 2. The process according to claim 1, wherein the alkali silicate is sodium silicate having a composition of the formula: Na ₂ O.mSiO ₂ where m is a number from 1 to 4. 3. The method according to claim 1, wherein the amorphous silica nucleating agent has a particle diameter of 1/10 or less of the particle diameter of silica particles finally produced. 4. The method according to claim 1, wherein the water-soluble organic polymer is an anionic water-soluble polymer. 5. The method according to claim 1, wherein the water-soluble organic polymer is a nonionic water-soluble polymer. 6. The method according to claim 1, wherein the amorphous silica nucleating agent is silica sol, silica gel or anhydrous silica powder having a particle size of 1 μm or less. 7. The method according to claim 1, wherein the acid is sulfuric acid. 8. Amorphous silica nucleating agent is used as total silica (Si
The manufacturing method according to claim 1, wherein 1 to 80% by weight per 0 ₂ ) is added. 9. A water-soluble organic polymer is used in an amount of 5 to 1 per silica.
The manufacturing method according to claim 1, wherein the addition amount is 00% by weight.