JPS6228085B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a novel hydrated silicic acid and a method for producing the same. The hydrated silicic acid of the present invention not only has excellent properties as a carrier for agricultural chemicals, but also is an excellent hydrated silicic acid that can be suitably used in conventionally known fields of use of hydrated silicic acid. Further, the method for producing hydrated silicic acid of the present invention can provide excellent properties with an industrially simple technique. Hydrous silicic acid is produced by various methods and used for various purposes. For example, hydrated silicic acid is used in synthetic rubber reinforcing agents, synthetic resin fillers, agricultural chemical carriers, dental fillers, and the like. However, since hydrated silicic acid is a product in the form of agglomerated ultrafine powder with a unit particle size of 10 to 50 mμ, it may not exhibit sufficiently excellent properties depending on its handling. Furthermore, when used as a carrier for carrying pesticides, for example, conventional hydrated silicic acid is not always satisfactory because it tends to adhere to walls, mixing blades, outlet ports, etc. during the process of absorbing pesticide ingredients. The present inventors have been conducting research on the production of hydrated silicic acid for many years. Furthermore, as a result of pursuing various changes in the properties of hydrated silicic acid, such as changes over time and changes during handling, we surprisingly discovered that a specific hydrated silicic acid exhibits stable properties for a wide variety of uses. We have completed and proposed the present invention. That is, the present invention has a pore radius of 150 Å in the pore size distribution.
The volume occupied by the following pores is 0.5cc/g or more, 1
It is a hydrous silicic acid containing 55% or more of secondary agglomerated particles having a particle size of 46 μm or less and secondary agglomerated particles having a particle size of 149 μm to 6000 μm. In addition, the present invention involves neutralizing an alkali silicate with an acid to produce hydrated silicic acid, and then processing a cake containing the hydrated silicic acid or dried hydrated silicic acid using a jet pulverizer or an impact pulverizer, so that the primary agglomerated particles are 46μ or less. The pulverized material is compressed and degassed at a compression pressure of 0.1 to 3 kg/ ^cm2 , and the pore radius of the pore size distribution is
55% when the volume occupied by pores of 150 Å or less is 0.5 cc/g or more, the particle size of primary agglomerated particles is 46 μ or less, and the particle size of secondary agglomerated particles is 149 μ to 6000 μ
The present invention also provides a method for producing hydrated silicic acid containing the above. The present invention will be described in detail below, but in the present invention, the target object, that is, the product, is referred to as hydrated silicic acid, and the intermediate product leading to the product is referred to as hydrated silicic acid. Furthermore, in the present invention, the term "primary agglomerated particles" refers to the particle size obtained from the product by wet-method particle size measurement, and the "secondary agglomerated particles" refers to the particle size obtained from the product by dry-method particle size measurement. It is. In addition, wet method powderiness measurement refers to a measurement method based on the "powderyness test method" of the physical property test method in the official agricultural chemical testing method. For example, this measurement method is supervised by Terumaro Suzuki and published by Nankodo, "Commentary on Official Pesticide Inspection Methods" (published October 31, 1972).
It is described on page 156. Furthermore, dry method powder size measurement is expressed as the cumulative weight percentage of hydrated silicic acid remaining on the sieve when powder flowability is measured using RLCarr's powder flowability evaluation method. . The dry method particle size measurement method is used, for example, in "Powder Technology Research Society Journal", Vol. 6, No. 4, published by Powder Technology Research Society.
The hydrated silicic acid remaining on the sieve may be expressed as an integrated weight percentage according to the method described in P. 264 to 272 (1969), especially P. 265 to P. 266, in the method for measuring tackiness. The particle diameter of the primary agglomerated particles of the present invention is determined by the wet method fineness measurement of hydrated silicic acid described above, but usually a 300-mesh sieve is used to obtain particles with a state in which 95% or more passes through the 300-mesh sieve. It may be the diameter. The particle size of the primary agglomerated particles of the hydrated silicic acid of the present invention is extremely small compared to conventionally known hydrated silicic acids. If the primary agglomerated particles have a coarse particle size exceeding 46μ, for example, when used as a carrier for agricultural chemicals, not only will the adsorption power of the agricultural chemical ingredient be weak and the suspension properties will be poor, but also the cohesive force of the secondary agglomerated particles will be reduced. Since this is small, the effect of compression and deaeration is small, and when the agricultural chemical raw material is mixed, the secondary agglomerated particles tend to collapse, resulting in poor workability, which is also unfavorable in terms of utilization rate. Therefore, the particle size of the primary agglomerated particles of hydrated silicic acid in the present invention is
It must be 46μ or less. A typical manufacturing method for hydrated silicic acid whose particle size as determined by the wet method powderiness measurement passes the requirements of the present invention will be described later, but in general, coarse primary agglomerated particles obtained by a conventional method are processed by a mechanical method. The purpose can be achieved by pulverizing it into a fine powder. The hydrated silicic acid of the present invention must contain 55% or more of secondary agglomerated particles, that is, particles having a particle size in the range of 149 μ to 6000 μ by dry method particle size measurement. If the particle size of the secondary agglomerated particles is smaller than the above range, it will cause major defects in workability such as adhesion to equipment when handling hydrated silicic acid and a decrease in utilization rate. In addition, if the particle size of the secondary agglomerated particles is larger than the above upper limit, for example, when used as a carrier for agricultural chemicals, the fluidity is poor and the dusting machine is clogged, and when used as various fillers, the dispersibility is poor and re-pulverization is required. This is not desirable because it requires In the present invention, the particle diameters of the primary agglomerated particles and the secondary agglomerated particles are independently different from each other, but the effect of the present invention is exhibited only when both of the above properties are satisfied. cannot be considered separately. In particular, since products of hydrated silicic acid are constructed by agglomeration of unit particles, products that deviate from the above properties will have completely different properties. For example, even if the secondary agglomerated particle size is within the limited range of the present invention, if the primary agglomerated particle size is coarse, it will no longer be possible to exhibit the effects of the present invention not only in terms of properties but also as a product. Of course, the same thing can be said in the opposite case. When the hydrated silicic acid is used as a carrier for adsorbing drugs, such as the agricultural chemical carrier of the present invention, the volume occupied by pores with a pore radius of 150 Å or less in the pore size distribution of the hydrated silicic acid is 0.5 cc/g or more, and the oil absorption is A large one is preferable. Generally oil absorption is 1.5 to 3.5
A range of cc/g is preferred. The pore size distribution is measured by various methods, but the volume occupied by pores with a pore radius of 150 Å or less in the pore size distribution is measured by a mercury porosimeter method.
Moreover, the oil absorption amount of hydrated silicic acid is the result of measurement according to JIS K 6220. Hydrous silicic acid in which the volume occupied by pores of 150 Å or less is 0.5 cc/g or more, preferably 0.6 cc/g or more, is extremely excellent in handling, oil absorption rate, etc. Among the above pore size distributions, those in which the volume occupied by pores of 150 Å or less (generally, pores between 50 and 150 Å) occupy 0.5 cc/g or more are special compared to known hydrous silicic acids. It can be produced by selecting the reaction conditions between an alkali silicate and a mineral acid to produce the desired product. That is, the pore size distribution of hydrated silicic acid is determined by the reaction conditions for obtaining hydrated silicic acid, and is not affected by the handling of hydrated silicic acid. To illustrate a typical manufacturing method, when producing hydrated silicic acid by adding acid to an aqueous alkali silicate solution in multiple stages, the silica concentration (C) in the aqueous alkali silicate solution when adding the second stage acid is 2 to 2. 6g/100c.c., the first stage acid addition ratio (A) to the total acid addition amount is 20 to 50%, and the reaction temperature (T) is 70 to 100℃, and the general formula X = { 1/T-65+(A/10)〓}/C〓The value of X (hereinafter simply referred to as the
It is preferable to select each condition so that the value is 1.28 to 1.55. The hydrated silicic acid, that is, the pore radius of the pore size distribution
55% when the volume occupied by pores of 150 Å or less is 0.5 cc/g or more, the particle size of primary agglomerated particles is 46 μ or less, and the particle size of secondary agglomerated particles is 149 μ to 6000 μ
The method for producing the silicic acid contained above is not particularly limited, and any method may be used. Typical methods that are generally easy to use industrially will be described below. It is known to neutralize an aqueous solution containing an alkali silicate with an acid such as a mineral acid such as hydrochloric acid or sulfuric acid to obtain hydrated silicic acid. In the present invention, these known conditions for producing hydrated silicic acid may be employed as they are. However, the volume occupied by pores of 150 Å or less in the pore size distribution is 0.5 cc/
In order to obtain hydrated silicic acid with a weight of more than 100 g, it is necessary to strictly control the production conditions of hydrated silicic acid as described above. Hydrated silicic acid obtained by neutralizing an alkali silicate with an acid is generally filtered to form a cake, or the cake is dried to obtain dry hydrated silicic acid. The dried hydrated silicic acid obtained in this state generally has a primary agglomerated particle size larger than the specification of the present invention.
100% or close to 100% residue on the sieve. Therefore, it is generally necessary to grind the hydrated silicic acid into the primary agglomerated particles of the present invention. Further, when using a cake containing hydrated silicic acid obtained in the above reaction, it is preferable to dry the cake to a state where the primary aggregated particles have the above particle diameter at the same time or before or after the pulverization. Generally, when using a cake containing hydrated silicic acid, it is preferable to use a drying mill that pulverizes and dries at the same time. As the pulverizer for pulverizing the hydrated silicic acid, it is preferable to use a jet pulverizer or an impact pulverizer because it is necessary to pulverize the secondary agglomerated particles into a state in which they are easily re-agglomerated to meet the conditions of the present invention. If a grinder that causes wear, such as a ball mill or a tube mill, is used as a grinder, the primary agglomerated particles will become smaller, but the re-agglomeration between the primary agglomerated particles will be poor and the conditions for the secondary agglomerated particles of the present invention will be satisfied. Often not. Therefore, it is preferable to use a grinder that does not cause wear for grinding the hydrated silicic acid in the present invention. In this sense, the jet pulverizer or impact pulverizer is most preferred. Typical jet crushers include jettomizers, supersonic jet mills, etc.
Typical impact crushers include the Nara free crusher, coffee mill, and turbo mill (all are trade names). Some of these pulverizers have a built-in classifier, but those without a classifier need to be pulverized until the particle size of the primary agglomerated particles falls within the conditions of the present invention. If the pulverized hydrated silicic acid is used as is, the primary agglomerated particles pass the conditions of the present invention, but the secondary agglomerated particles often fail to satisfy the conditions of the present invention. In such a case, industrially, it is necessary to compress and deaerate the pulverized material to actively re-agglomerate the primary agglomerated particles. The compression is not particularly limited, and it is sufficient to simply apply a necessary load to the crusher. The compression pressure is 1
Although it varies depending on the properties of the secondary agglomerated particles, the pressure means, etc., it may generally be selected appropriately from the range of 0.1 to 3 kg/cm ² . Further, the compression may be carried out at an appropriate location in the conventional process, such as in a tank for storing the pulverized product, or during bagging, etc., as required. If the pulverized material is simply compressed, since the hydrated silicic acid itself has a large porosity, the air between the primary agglomerated particles cannot be removed, and the primary agglomerated particles may scatter through the gaps during compression, or the compressive force may become large, resulting in bagging. If compression treatment is attempted, phenomena such as destruction of the packaging bag may occur. In order to avoid this phenomenon, it is preferable to perform deaeration at the same time as compression or before and after compression. The deaeration is not particularly limited, and the air contained therein may be removed naturally or actively as in the case of compression, but in general, it is most preferable to actively draw out the air while the pulverized material is compressed. Of course, the effect of the present invention can be fully exhibited even if a means of degassing before and after compression is used, but industrially, as described above, compression and degassing are performed simultaneously or sequentially in a hydrated silicic acid tank, or hydrated silicic acid is packed in bags. What is necessary is to adopt a method of compressing while degassing. As a typical example of the latter, when packing bags, the compression and compression of the present invention can be sufficiently achieved by using a gel bag, a bag press (all product names), etc.
May cause deflation. Although the typical manufacturing method of hydrated silicic acid of the present invention has been described above, the present invention is not limited to the above manufacturing method. For example, hydrated silicic acid obtained by neutralizing alkali silicate with acid has the above pore volume as a product, the particle size of the primary aggregate particles is 46μ or less, and
55 particles with a particle size of 149μ to 6000μ
% or more of hydrated silicic acid, and may be obtained by directly reacting an alkali silicate with an acid without going through mechanical means. As is clear from the above description, the present invention provides a hydrous silicic acid having small primary agglomerated particles and large secondary agglomerated particles. Hydrous silicic acid with such properties not only has a good adsorption rate when used as a carrier for adsorbing drugs, but also greatly improves workability when adsorbing drugs, such as adhesion to the vessel wall. Therefore, the utilization rate of hydrated silicic acid can be improved. These effects can be said not only to drug adsorption but also to conventional uses of hydrated silicic acid. Therefore, the degree of industrial contribution of the present invention is immeasurable. EXAMPLES In order to explain the present invention more specifically, Examples and Comparative Examples will be described below, but the present invention is not limited to these Examples. In addition, the particle diameter of the primary agglomerated particles of hydrated silicic acid in the Examples and Comparative Examples, and the particle diameter of the secondary agglomerated particles are 149 μ to 6000 μm.
The cumulative weight ratio of μ, pore volume, mixing test, apparent specific gravity, oil absorption amount, and oil absorption rate were measured by the following methods. (1) Particle size of primary agglomerated particles: This was conducted in accordance with the official pesticide inspection method (using a 300 mesh sieve). (2) Cumulative weight ratio of 149μ to 6000μ of secondary agglomerated particles: Measured using a powder tester (manufactured by Hosokawa Iron Works) according to RLCarr's powder fluidity evaluation method. (3) Pore volume: 1520 manufactured by CARLO ERBA
Measurements were made using a type mercury porosimeter (Dilatometer type SM3, capillary: 3 mm, 0.07065 cm ² ). (4) Mixing test Figure 1 is a schematic diagram showing the equipment used for the mixing test. A hydrous silicic acid sample 4 was placed in a polyurethane container 1 with an internal volume of 500 ml, equipped with a rotary stirring blade 2 rotated by a motor M and an addition port 3 as shown in FIG.
Pour 20g and 20ml of agricultural chemical ingredient from addition port 3 9-10
Mix for 30 minutes from the start of dropping at a rotation speed of 200 r.Pm using a rotating stirring blade. After mixing, the sample was taken out, and the weight of the sample adhering to the inner wall of the container and the rotating stirring blade was measured. (5) Apparent specific gravity: Performed according to JIS K 6220. (6) Oil absorption: Conformed to JIS K 6220. (7) Oil absorption rate: Figures 2 to 4 are schematic diagrams showing a method for measuring oil absorption rate. The hydrated silicic acid sample 4, which has been sieved with a 32-mesh sieve, is placed in a container 5 with an open top, 70 mm in diameter and 16 mm in height, as shown in FIG. 2, up to the angle of repose of the sample. Next, as shown in Figure 3, a weight (total weight 100 g), which includes a weight 7 placed on a watch glass 6 with a diameter of 110 mm, was placed on the sample and compressed.
Pull up after 15 seconds. Then, as shown in Figure 4, 2 ml of boiling oil 8 was applied to the surface of the compressed sample.
The time required from the time the boiled oil came into contact with the sample until all the boiled oil was absorbed into the sample was measured. The measurements were conducted indoors at a temperature of 20°C. Example 1 Commercially available sodium silicate (SiO ₂ /Na ₂ O=3.03,
SiO ₂ 26.4%) 7.6 m ³ and Na ₂ O ₄ (Na ₂ O 1.48%) 33.8
m ³ and 3.64 m ³ of water were placed in a 60 m ³ internally heated reaction tank equipped with stirring blades, and while stirring, 1.99 m ³ of sulfuric acid (22 g/100 ml) was added over about 10 minutes to perform the first acid addition. After the addition is complete, blow in steam while stirring and raise the temperature to 95°C over 20 minutes. After raising the temperature, ripening is performed at the same temperature for 7 minutes. The silica concentration at this time was 3.9 g/100 c.c. Thereafter, neutralization was restarted, and 2.9 m ³ of the sulfuric acid was added over a period of 90 minutes to neutralize the remaining alkali, and the pH of the solution was brought to 6 to complete the reaction. The X value under this reaction condition was 1.395. Next, the pH of this solution is adjusted to 4.4 so that the pH of the product of hydrated silicic acid after drying is 5.5 to 6.5. This solution is filtered and washed with water, and a filter cake containing hydrated silicic acid is dispersed using a dispersing device to form a highly concentrated silicic acid suspension and dried with a spray dryer to obtain a dried hydrated silicic acid product. Next, this dried material is crushed by a jet crusher at a crushing pressure of 3
Kg/cm ² , 4 Kg/cm ² and 6 Kg/cm ² were crushed and filled into paper bags, and compressed at a pressure of 0.16 Kg/cm ² , 1 using a hydraulic press machine (Tanimoto Kikai Seisakusho), except for No. 1 in Table 1.
It was pressurized at a pressure of Kg/cm ² and 3 Kg/cm ² and air corresponding to the pressurization was naturally extracted and deaerated. Using this product, we conducted an adsorption/mixing test for agricultural chemical ingredients. The pesticide active ingredient has the chemical formula 2-Secondarybutylphenyl-N
- Represented by methyl carbamate (hereinafter simply abbreviated as BPMC), and the product name "Batsusa" was used. Table 1 shows the results of the crushing, degassing and BPMC tests on this hydrated silicic acid. The jet crusher is PJM (trade name) PJM- manufactured by Nippon New Matsushiku Kogyo KK.
Type I (product name) and FLUID ENERGY PROCESSING and
EQUIPMENT COMPANY) model 0202 (hereinafter simply abbreviated as JOM) was used. The physical properties of the hydrated silicic acid obtained above were as follows. Moisture (105℃ 2hr): 7.9% PH (5% suspension): 6.2 Oil absorption (ml/100g): 250 Apparent specific gravity (50g/cm ² loading type): 0.10 to 0.18g/cm ³ Pores below 150Å Volume (cc/g): 0.77 Oil absorption rate (sec): 80

[Table] Comparative Example 1 Hydrous silicic acid was obtained in the same manner as in Example 1 except that the pulverized product was not compressed and degassed. Using this hydrated silicic acid, an adsorption and mixing test for agricultural chemical ingredients was conducted in the same manner as in Example 1. The results are shown in Table 2.

[Table] Example 2 The dried hydrated silicic acid of Example 1 was heated in a micron mill and a Philips coffee mill (home use) for 20 minutes.
Example 1
Similarly, the compression pressure is 1Kg/cm ² , 3Kg/cm ² and 5Kg/cm ²
It was pressurized and degassed at a pressure of . This powder was used to conduct adsorption and mixing tests for active agricultural chemicals (BPMC). The results are shown in Table 3.

[Table] Comparative Example 2 Hydrous silicic acid was obtained in the same manner as in Example 2 except that the pulverized material was not compressed and deaerated. Using this hydrated silicic acid, an adsorption and mixing test for agricultural chemical ingredients was conducted in the same manner as in Example 2. The results are shown in Table 4.

[Table] Comparative Example 3 The dried hydrated silicic acid of Example 1 was pulverized using a magnetic ball mill with an inner diameter of 110 mm, the pulverized product was filled into a paper bag, and then compressed at a compression pressure of 3 in the same manner as in Example 1.
It was pressurized and degassed at a pressure of Kg/cm ² . Using this product, an adsorption and mixing test for agricultural chemical ingredients was conducted in the same manner as in Example 1. The results are shown in Table 5.

[Table] Comparative Example 4 Hydrous silicic acid was obtained in the same manner as in Example 1 except that the jet pulverizer PJM was used and deaeration was performed at a crushing pressure of 3 kg/cm ² and a compression pressure of 1 kg/cm ² . This hydrated silicic acid was sieved using a standard sieve of 149 μm, and the product under the sieve was subjected to an adsorption and mixing test for agricultural chemical ingredients in the same manner as in Example 1. As a result, the adhesion amount of BPMC in the adsorption mixing test was 2.0g. Example 3 Commercially available Tokusil NR (manufactured by Tokuyama Soda Co., Ltd.) was pulverized using a jet pulverizer PJM at a pulverizing pressure of 4 kg/cm ² . This pulverized product was compressed at a pressure of 1 as in Example 1.
Compression and deaeration were performed at kg/cm ² to obtain hydrous silicic acid. Using this hydrated silicic acid, an adsorption and mixing test for agricultural chemical ingredients was conducted in the same manner as in Example 1. Table 6 shows the properties of the hydrated silicic acid and the above test results. The physical properties of the hydrated silicic acid were as follows. Moisture (105℃ 2hr) 7% PH (5% suspension) 6.3 Oil absorption (ml/100g) 240 Apparent specific gravity (50g/cm ² loading type) 0.17 Pore volume below 150A [cc/g] 0.32

[Table] Comparative Example 5 An adsorption and mixing test of agricultural chemical ingredients was conducted in the same manner as in Example 1 using the commercially available Tokusil UR (manufactured by Tokuyama Soda Co., Ltd.). The results are shown in Table 7. The physical properties of Tokusil UR are as follows. Moisture (105℃ 2hr) 5.5% PH (5% suspension) 5.6 Oil absorption (ml/100g) 180 Apparent specific gravity (50g/cm ² loading type) 0.28 150A or less Pore volume [cc/g] 0.45

[Table] Example 4 A dried product of hydrated silicic acid obtained in the same manner as in Example 1 was ground for 20 seconds using a Philips coffee mill (for home use). A cloth was placed on a Buchner funnel with an inner diameter of 125 mm, 30 g of the above-mentioned pulverized material was placed on the cloth, and the cloth was placed on top of the cloth. This Buchner funnel was attached to a suction filtration bottle, a weight of 20 kg was placed on the flask while suction was being applied, and the flask was kept in this state for 5 minutes to degas it and obtain hydrous silicic acid. Using this hydrated silicic acid, an adsorption and mixing test for agricultural chemical ingredients was conducted in the same manner as in Example 1. The results are shown in Table 8.

[Table] Example 5 In Example 1, the amount of sulfuric acid added in the first stage was
Hydrated silicic acid was obtained in the same manner as No. 3 in Table 1 of Example 1 except that the amount of sulfuric acid added was changed to 1.74 m ³ , the remaining amount of sulfuric acid was changed to 3.08 m ³ and the reaction temperature was changed to 85°C. Table 1 shows the silica concentration (C), acid addition ratio (A), reaction temperature (T), and (X) values. Further, Table 9 shows the results of tests similar to those in Example 1 and other measurements. Example 6 The same sodium silicate aqueous solution and Boron's sulfur aqueous solution as in Example 1 were used in an internal volume of 2.27 m ³ and 13.5 m ³ , respectively, and 2.02 m ³ of water.
25 m ³ was fed into an internally heated reactor equipped with a stirrer.
Then, 0.44 m ³ of sulfuric acid (22 g/100 c.c.) was added over about 10 minutes at a temperature in the range of 40-45° C. while stirring. Table 9 shows the addition ratio (A) of the above sulfuric acid. After the first acid addition was completed, water vapor was blown into the mixture while stirring was continued, and the temperature was raised to the reaction temperature (T) shown in Table 1 over 20 minutes. The silica concentration (C) at this time is shown in Table 1.
After the solution was kept at the above reaction temperature for 10 minutes, the remaining 1.03 m ³ of sulfuric acid was continuously added over 100 minutes while stirring to bring the pH of the solution to 6 and complete the reaction.
Table 9 shows the X values determined from (C), (A), and (T) above. Hydrous silicic acid was obtained in the same manner as No. 3 in Table 1 of Example 1. Example 1 about the obtained hydrated silicic acid
The same measurements and tests were carried out. The result is the 9th
Shown in the table. Example 7 The same sodium silicate aqueous solution and Boron's salt aqueous solution as in Example 1 were added to 6.1 and 27.0, respectively, and water was 6.9 to an inner volume of
50, was fed to an externally heated reaction tank equipped with a stirrer.
Then, 1.58 g of sulfuric acid (22 g/100 c.c.) was added over about 10 minutes at a temperature in the range of 40 to 45° C. while stirring. The addition ratio (A) of the above sulfuric acid is shown in Table 1. The silica concentration (C) at this time is shown in Table 9. After the first stage of acid addition was completed, the temperature was raised to the reaction temperature (T) shown in Table 9 over 20 minutes while stirring was continued. After keeping the solution at the above reaction temperature for 10 minutes, the remaining 2.29% of sulfuric acid was continuously added over 100 minutes while continuing to stir.
The reaction was completed by setting the pH to 6. (C), (A) above,
Table 9 shows the X values determined from (T). Hydrated silicic acid was obtained in the same manner as No. 3 in Table 1 of Example 1.
The obtained hydrated silicic acid was subjected to the same measurements and tests as in Example 1, and the results are shown in Table 1. Example 8 Using the same aqueous sodium silicate solution, aqueous salt solution, and reaction tank as in Example 4, an aqueous sodium silicate solution of 8.79%
, 27.0 g of aqueous Bowel's salt solution and 4.2 g of water were supplied to the reaction tank. Below, the amount of sulfuric acid added in the first stage is 2.56
Then, hydrated silicic acid was obtained in the same manner as in Example 7 except that the amount of the remaining sulfuric acid added was 3.03 and the reaction temperature was changed. Table 9 shows silica concentration (C), acid addition ratio (A),
Reaction temperature (T) and (X) values are shown. In addition, the results of the same measurements and tests as in Example 1 are presented in the 9th section.
Shown in the table.

【table】 [Brief explanation of the drawing]

Figure 1 shows a mixing test device used to determine the properties of hydrated silicic acid. Also, Figures 2, 3 and 4
The figure is an explanatory diagram for explaining a method for measuring the oil absorption rate of hydrous silicic acid. In the figure, M is a motor, 1 is a plastic container, 2 is a rotating stirring blade, 3 is an addition port, 4 is a hydrous silicic acid sample, 5 is a container, 6 is a watch glass, 7 is a weight, 8
indicate boiled oil, respectively.

Claims (1)

[Scope of Claims] 1. The volume occupied by pores with a pore radius of 150 Å or less in the pore size distribution is 0.5 cc/g or more, the particle size of the primary agglomerated particles is 46 μ or less, and the particle size of the secondary agglomerated particles Hydrous silicic acid containing 55% or more of 149μ to 6000μ. 2. Neutralize an alkali silicate with an acid to produce hydrated silicic acid, and then process the cake containing the hydrated silicic acid or dried hydrated silicic acid with a jet pulverizer or an impact pulverizer so that the primary agglomerated particles are 46μ or less. Grind the pulverized material to 0.1~
By compressing and degassing at a compression pressure of 3 kg/ ^cm2 , the volume occupied by pores with a pore radius of 150 Å or less in the pore size distribution is
At 0.5cc/g or more, the particle size of primary agglomerated particles is 46μ
or less and the particle size of the secondary agglomerated particles is 149μ to 6000
A method for producing hydrated silicic acid, characterized by obtaining hydrated silicic acid containing 55% or more of μ. 3. The hydrated silicic acid according to claim 1, wherein the volume occupied by pores of 150 Å or less in the pore size distribution of the hydrated silicic acid is 0.6 cc/g or more. 4 Hydrated silicic acid obtained by neutralizing alkali silicate with acid is obtained by adding acid to an aqueous alkali silicate solution in multiple stages, so that the ratio of acid addition in the first stage (A) to the total amount of acid added is 20 to 50.
%, the silica concentration (C) in the aqueous alkali silicate solution when adding the second stage acid is selected from the range of 2 to 6 g / 100 c.c., the reaction temperature (T) is selected from the range of 70 to 100 ° C., and the formula The method for producing hydrated silicic acid according to claim 2, wherein the reaction is carried out under conditions such that the value of X expressed as ={1/T-65+(A/10)}/C is 1.28 to 1.55.