JPH085658B2 - Method for producing granular amorphous silica and spherical particles of 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 process of neutralizing an acid of alkali silicate and a method for producing the amorphous silica. It relates to crystalline silica spherical particles.

[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 an 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 an alkali metal alginate, an ammonium alginate, 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.

[0007] The present inventors have found that when an acrylamide polymer is added among water-soluble polymers during the neutralization process of an alkali silicate solution with an acid, fine spherical particles of partially neutralized alkali silicate are collected. It has been found that it precipitates efficiently.

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. Still another object of the present invention is to provide amorphous silica spherical particles which are porous amorphous silica and have a spherical shape as a whole and have a high refractive index.

[0009]

According to the present invention, an alkali silicate aqueous solution, an acrylamide polymer and a partially neutralized acid aqueous solution are mixed and the mixture is left to stand for partial alkali silicate neutralization. There is provided a method for producing granular amorphous silica, which comprises producing a granular material composed of a substance, separating the granular material, and neutralizing with an acid.

Also according to the invention, the BET specific surface area is 1
00 to a non-crystalline silica which is 800 m ² / g, the entire clear spherical particles, and the ratio of the particles of the major axis (D _L) and the minor axis _{(D S) (D S /} D L) 80% or more of the particles having a sphericity of 0.90 to 1.00 are represented, and in the formula “Equation 1” D ₂₅ / D ₇₅ , D ₂₅ is ₂₅ of the volume-based cumulative particle size distribution curve by the Coulter counter method. % Represents the particle size, and D ₇₅ represents the 75% particle size. Amorphous silica spherical particles having a sharpness of the particle size distribution defined by 1. to 2.0 and a refractive index in the range of 1.46 to 1.50 are provided.

[0011]

In the present invention, among various water-soluble polymers, the acrylamide polymer is used as an aggregating and growing agent for growing a partially neutralized product of alkali silicate into a granular material. It is based on the finding that it acts specifically in terms of regularity.

In Table 1 described later, a transparent mixed solution is prepared from an aqueous sodium silicate solution, various water-soluble polymer solutions, and a partially neutralized amount of sulfuric acid, and the mixed solution is prepared at 20 ° C.
The results of measuring the yield (based on SiO ₂ ) of the partially neutralized alkali silicate that precipitates when left for 14 hours at the temperature and the particle shape and particle size of the granular material are shown.

According to the results of "Table 1", not only sodium alginate, starch, and gelatin described in the above-mentioned prior art but also nonionic water-soluble highly soluble polyvinyl alcohol (PVA), polyethylene glycol (PEG), etc. Molecules, anionic water-soluble polymers such as carboxymethyl cellulose (CMC) and sodium polyacrylate (not shown in "Table 1" but not spherical), and cationic water-soluble polymers such as polyamine-based polymer flocculants When used, the yield is as low as about 40% or less, and even if the yield is relatively high, the filterability is extremely poor, and the particle shape and particle size are irregular, whereas the acrylamide polymer is added. With such a product, the surprising fact that the yield is as high as 70% or more and the particle shape and particle size are almost constant becomes clear.

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 is, the narrower the particle size distribution is, and the larger this value is, the wider the particle size field is. 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, minor axis and major axis (D _L) in the particle cross sections (Torukagemen) (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) 0.95
80% or more of the total amount is in the range of ˜1.00, which is remarkably excellent as compared with the case where other polymer agents are added.

In the present invention, the granular material composed of a partially neutralized product of alkali silicate has a fine structure in which silica sol-sized spherical primary particles having a polymer chain of an acrylamide polymer as a core are aggregated into a tuft of grapes. It is thought to be taking. The attached drawing "FIG. 4" schematically shows the fine structure in the granular material. The acrylamide polymer and the silica primary particles are represented by the formula:

Embedded image In the formula, n is the amount of silica that can be present as sol-sized particles. It is recognized that there is a hydrogen bond between the amide group and the silanol group on the silica surface. In this way, the excellent action of the acrylamide polymer as an aggregative growth agent in the present invention can be explained.

In the present invention, the fact that the acrylamide polymer is contained in the neutralized product consisting of the partially neutralized product of alkali silicate is contained inside when this product is neutralized with an acid. This is confirmed by the fact that the acrylamide polymer along with the alkaline component is extracted outside the particles. Even when neutralized with this acid, the form of the granular material once formed is retained as it is, and since components other than amorphous silica are removed, the granular silica has a high yield and a good spherical particle shape and sharpness. It can be obtained with a wide particle size distribution.

Since the granular amorphous silica of the present invention is an aggregate of primary silica particles as described above, it has a relatively large BET specific surface area, generally 100 to 800 m ² / g, particularly 150 to 600 m ² / g. Since it is in the range and the degree of aggregation is higher than that of silica gel, the refractive index (25
C.) is as large as 1.46 to 1.50.

[0020]

Preferred Embodiment of the Invention

(Alkali silicate) As the 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 granules. 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.

(Acrylamide Polymer) The acrylamide polymer used as the coagulant growth agent for silica particles in the present invention has the formula

[Chemical 3] The acrylamide repeating unit represented by
This acrylamide polymer is preferably a homopolymer of acrylamide, but can be copolymerized with acrylamide repeating units within the range of 70 mol% or more, particularly 90 mol% or more of the total acrylamide repeating units. It may contain repeating units of various monomers, for example, ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid, vinyl ethers, (meth) acrylic acid esters and the like. Further, the acrylamide polymer may contain an anionic unit modified to a carboxyl group by hydrolysis or a cationic unit esterified with an aminoalkyl group or a quaternary ammonium alkyl group.

The acrylamide polymer used in the present invention is preferably one having a very low molecular weight, and its weight average molecular weight (M _W ) is generally 10,000 to 3,000,000, particularly 1
It is desirable to be in the range of 0,000 to 2,000,000. If the molecular weight of the acrylamide polymer is too high, it tends to be difficult to form and precipitate the particulate matter. This is considered to be because when the molecular weight becomes too high, the entanglement of the molecular chains increases, and it becomes difficult to form the tufted aggregate structure described above.

In the acrylamide polymer, the relationship between the weight average molecular weight (M _W ) and the intrinsic viscosity (η) is

## EQU2 ## η = 3.73 × 10 ^-4 × (M _W ) ^0.66 However, the intrinsic viscosity η is represented by the measurement at 30 ° C. in 1N-sodium nitrate solution.

The acrylamide polymer preferably used in the present invention has a carboxyl group in a free or salt form in an amount of 0.2 to 50 mmol, particularly 0.1.
It is contained at a concentration of 5 to 20 mmol. The anionic groups in the polymer chains seem to act to stretch the molecular chains in water by the electrostatic repulsion of their homopolar groups, facilitating the formation of tufted aggregate structure of primary silica particles. . This acrylamide polymer has a SiO ₂ standard of 5
To 100% by weight, particularly 10 to 50% by weight, and when the amount is less than the above range, it is not preferable from the viewpoint of precipitation yield of the particulate matter, and on the other hand, even if it is used in an amount larger than the above amount. It has no particular merit and is economically disadvantageous.

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. Further, a neutral salt may be added to these acids. The amount of acid used during mixing is such that a homogeneous mixed solution (clear) is produced by partial neutralization, and the pH of the mixed solution is 10.2 to 11.
It is preferable to use it in an amount of 2, especially 10.5 to 11.0.

(Precipitation of Granules) In the present invention, the order of addition of the above-mentioned components is not limited, and for example, the acrylamide polymer may be added after the acid is added to the alkali silicate aqueous solution, or vice versa. The acid may be added after adding the acrylamide polymer to the alkali silicate aqueous solution. Of course, these may be added at the same time. After thoroughly mixing and homogenizing each component, the mixed solution is allowed to stand to precipitate the partially neutralized granular material.

The precipitation 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 and acrylamide 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.
00 to a non-crystalline silica which is 800 m ² / g, the entire clear spherical particles, and the ratio of the particles of the major axis (D _L) and the minor axis _{(D S) (D S /} D L) 80% or more of the particles having a sphericity of 0.90 to 1.00 are represented, and in the formula “Equation 1” D ₂₅ / D ₇₅ , D ₂₅ is ₂₅ of the volume-based cumulative particle size distribution curve by the Coulter counter method. % Represents the particle size, and D ₇₅ represents the 75% particle size. It has a novel combination characteristic characterized in that the sharpness of the particle size distribution defined by 1 is 1.2 to 2.0 and the refractive index is in the range of 1.46 to 1.50.

The particulate amorphous silica is desired to be metal soap, resin acid soap, various resins or waxes, silane-based or titanium-based coupling agents, oxides or hydroxides of various metals, silica coating and the like. Can be applied by.

Utilizing these characteristics, various thermoplastic resins, for example, a homopolymer of propylene as a crystalline propylene copolymer, or an ethylene-propylene copolymer, a low-, medium-, high-density or linear polymer. Low density polyethylene, where linear low density polyethylene (LLDP
E) is ethylene and α-olefin having 4 to 18 carbon atoms
(Propylene, butene-1, pentene-1, hexene-
1,4-methylpentene-1, octene-1, decene-
1 or the like), an olefin resin such as an ionic cross-linked olefin copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ester copolymer, a polyethylene terephthalate, a polybutylene terephthalate Thermoplastic polyester such as 6-nylon,
Polyamide resins such as 6,6-nylon and 6,8-nylon, chlorine-containing resins such as vinyl chloride and vinylidene chloride, polycarbonates, polysulfones, etc. It can be used for imparting slip properties and anti-blocking properties to resin molded products. For this purpose, the amorphous silica of the present invention can be added in an amount of 0.01 to 10 parts by weight, particularly 0.02 to 2 parts by weight, based on 100 parts by weight of the thermoplastic resin.

Furthermore, the amorphous silica of the present invention can be blended into various paints, extender pigments for inks, adhesives, coating resin compositions and used for various purposes, and can also be used for pharmaceuticals, foods and agricultural chemicals. It can be blended as a carrier or a filler with respect to insecticides and the like. Specifically, for toner fluidity improver, high-grade abrasive, matte filler, catalyst carrier , chromatographic carrier, perfume carrier, putty Filler, adsorbent, fluidity improver, release agent, rubber filler, ceramics base, powder foundation, paste foundation,
It can be used as a base for cosmetics such as baby powder and cream.

[0033]

INDUSTRIAL APPLICABILITY According to the present invention, by adding an acrylamide polymer among water-soluble polymers in the neutralization process of an alkali silicate solution with an acid, granular amorphous silica can be obtained at a high yield. The obtained granular amorphous silica is an amorphous silica having a BET specific surface area of 100 to 800 m ² / g, and the entire particles have a clear spherical shape,
And the ratio of the particles of the major axis (D _L) and the minor axis (D _S) (D _S
/ D _L ) having a sphericity in the range of 0.90 to 1.00 has a sharp particle size distribution at 80% or more, and a refractive index in the range of 1.46 to 1.50. Certain amorphous silica spherical particles could be provided.

[0034]

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) Chemical composition The composition was measured according to JIS M-8852 silica analysis. (2) Apparent specific gravity It was measured according to JIS K-6220.6. (3) Oil absorption amount Measured according to JIS K-5101.19. (4) Specific surface area, pore volume Sorptomatic Series manufactured by Carlo Erba
s 1800 was used and measured by the BET method.

(5) Particle size The particle size was measured by a Coulter counter (TA-II type manufactured by Coulter Electronics) using an aperture tube of 50 μm. (6) Particle size by SEM Representative particles were selected from the photographic images obtained with a scanning electron microscope (S-570 manufactured by Hitachi), and the diameter of the particle image was measured using a scale, which was shown as the primary particle size. It was (7) Sphericity A typical particle is selected from the photographic images obtained with a scanning electron microscope (Hitachi S-570), and the major axis and minor axis of the particle image are measured using a scale to obtain the following formula. I asked from.

Equation 3] sphericity = short diameter (D _S) / long diameter (D _L)

(8) Refractive index A solvent having a known refractive index (α-
Bromnaphthalene, kerosene). Then La
According to rsen's oil immersion method, a few mg of sample powder was placed on a slide glass, 1 drop of a solvent with a known refractive index was added, a cover glass was placed, and the solvent was sufficiently immersed, and then the Becke line was moved with an optical microscope. Observe and ask. (9) Yield It was determined by dividing the produced SiO ₂ weight (calcined product at 860 ° C.) by the total amount of SiO ₂ in the sodium silicate used in the reaction.

[Equation 4] Yield (%) = [weight of generated SiO ₂ (g) / total amount of reacted SiO ₂ (g)] × 100

Example 1 A No. 3 sodium silicate solution (SiO ₂ component 22.3%, Na ₂ ) was placed in a 2 L stainless beaker.
O component 7.0%) was weighed 471 g (7% as SiO ₂ concentration in the total amount of liquid), added with 327 ml of pure water, and then placed in a constant temperature bath controlled at 20 ° C., while stirring, poly SiO ₂ was added to the total amount of SiO _2. Acrylamide polymer aqueous solution (about 10% aqueous solution, average molecular weight 50%)
10,000) was added. Then, 402 g of 7% sulfuric acid was added (the pH after the addition was 10.70). After the addition was completed, the stirring was stopped, the mixture was allowed to stand for 12 hours and then filtered, and the obtained silica cake was poured into pure water. Disperse again and pH is 3.
7% Sulfuric acid was added to 0 and sufficiently stirred, filtered, washed with water, further dried at 110 ° C., pulverized with a sample mill, and then calcined at 500 ° C. for 2 hours to obtain fine spherical silica powder. The properties of this powder are shown in Table 1 and an electron micrograph (SEM) is shown in FIG.

[0039]

[Table 1]

(Examples 2 to 3) The amount of the acrylamide polymer aqueous solution added was 14 in terms of anhydride with respect to SiO ₂ content.
%, 50%, and fine particle spherical silica was synthesized in the same manner as in Example 1 except that pure water was prepared so that the total amount became 1500 g. The properties of this powder are shown in Table 2.

[0041]

[Table 2]

(Examples 4 to 6) The static temperature of Example 1 was set to 2
Fine particle spherical silica was synthesized in the same manner as in Example 1 except that the temperature was 40 ° C., 40 ° C., and 80 ° C. The properties of this powder are shown in Table 2, and the SEM photograph of the powder synthesized at 2 ° C. is shown in FIG.

(Embodiment 7) The standing temperature of Embodiment 1 is 2 ° C.
Same as Example 1 except that the amount of the acrylamide polymer aqueous solution added was 10% in terms of anhydride with respect to SiO ₂ content, the standing time was 48 hours, and pure water was prepared so that the total amount became 1500 g. Fine particle spherical silica was synthesized.
The properties of this powder are shown in Table 3.

(Examples 8 to 9) The amount of sodium silicate in Example 1 was 370 g (SiO ₂ concentration 5.5%), 269 g (S
Fine particle spherical silica was synthesized in the same manner as in Example 1 except that pure water was prepared so that the total amount became 1500 g, with an iO ₂ concentration of 4%). The properties of this powder are shown in Table 3.

(Example 10) 438 g of sodium silicate (SiO ₂ component 24.0%, Na ₂ O component 9.9%) was added 7
Fine spherical silica was synthesized in the same manner as in Example 1 except that the amount of% sulfuric acid was 540 g and pure water was prepared so that the total amount was 1500 g. The properties of this powder are shown in Table 3.

Examples 11 to 12 As Example 1 except that the polyacrylamide aqueous solution used in Example 1 had a molecular weight of 300,000 and 1,200,000 and the anion degree of each was 0.3 mol%. In the same manner, fine particle spherical silica was synthesized. The properties of this powder are shown in Table 3.

Example 13 A mixed acid (7% sulfuric acid 286 g + 7% hydrochloric acid 86 g) was used in place of 7% sulfuric acid in Example 1, and the total amount was 1.
Fine particle spherical silica was synthesized in the same manner as in Example 1 except that pure water was adjusted to 500 g. The properties of this powder are shown in Table 3.

[0048]

[Table 3]

(Example 14) Fine particle spherical silica was synthesized in the same manner as in Example 1 except that 10.5 g of the reagent NaCl was added to 7% sulfuric acid. The properties of this powder are shown in Table 4 and a SEM photograph in FIG.

(Example 15) Fine particle spherical silica was synthesized in the same manner as in Example 1 except that 21 g of Na ₂ CO ₃ was added to the sodium silicate of Example 1. The properties of this powder are shown in Table 4.

(Examples 16 to 17) 500 g of the spherical silica hydrogel prepared in Examples 1 and 5 was diluted with 500 ml of pure water.
In addition, put it in a small pressure vessel with an internal volume of about 1 L and stir it for 15
It was hydrothermally treated at 0 ° C. for 2 hours. The properties of this powder are shown in Table 4, and the SEM photograph of Example 17 is shown in FIG.

[0052]

[Table 4]

Comparative Examples 1 to 7 4% sodium alginate solution (Comparative Example 1), 5% starch (MS-4600 manufactured by Nippon Shokuhin Kogyo Co., Ltd.) solution (Comparative Example 2) instead of the polyacrylamide aqueous solution of Example 1 5% gelatin solution (Comparative Example 3), 3%
CMC solution (Comparative Example 4), 4% PVA (Purchased by Kuraray Co., Ltd.
VA-117) solution (Comparative Example 5), polyethylene glycol # 400 (manufactured by Wako Pure Chemical Industries, Ltd.): water = 1: 3 aqueous solution (Comparative Example 6), 1% of polyamine-based polymer flocculant (MW = 8 million) Each solution (Comparative Example 7) was added and washed with water without acid neutralization,
Example 1 except that washing with dilute acid and washing with warm water were repeated.
Silica particles were prepared in the same manner as in. As a result, all of them had very poor filterability, and spherical particles having a uniform shape could not be obtained. The properties of this powder are shown in Table 1, Comparative Example 1,
A few SEM photographs are shown in FIGS. 8, 9 and 10.

(Comparative Example 8) Synthesis was carried out in the same manner as in Example 1 except that the amount of the acrylamide polymer aqueous solution added was 3% in terms of anhydride with respect to the SiO ₂ content and the total amount was 1500 g. However, spherical particles having a uniform shape were not obtained, and the yield was extremely low. The properties of this powder are shown in Table 2.

(Comparative Examples 9 to 10) In Example 1, the amounts of sodium silicate were 673 g (SiO ₂ concentration 10%) and 135 g (S
iO ₂ concentration 2%) was prepared with pure water so that the total amount would be 1500 g, but the SiO ₂ concentration 10% gelled into agglomerates when adding sulfuric acid and the SiO ₂ concentration was 2%.
The product prepared in Example 1 was hardly gelled even after 48 hours, and the resulting powder was a glassy hard product.

(Comparative Example 11) Synthesis was carried out in the same manner as in Example 1 except that the amount of 7% sulfuric acid added in Example 1 was 600 g and pure water was adjusted so that the total amount was 1500 g.
Before the addition of sulfuric acid was completed, gelation occurred (pH decreased to 10.11) and uniform spherical silica was not obtained.

(Comparative Example 12) A reaction was performed in the same manner as in Example 1 except that the amount of 7% sulfuric acid added in Example 1 was 200 g and pure water was prepared so that the total amount was 1500 g.
It did not gel even after 8 hours. PH at the end of pouring
Was 11.22.

(Comparative Example 13) The molecular weight of Example 1 was 800.
The total amount is 15
The reaction was performed in the same manner as in Example 1 except that pure water was prepared so that the amount became 00 g, but filtration was impossible, and spherical particles having a uniform shape could not be obtained.

Application Example 1 Application to Biaxially Stretched Polypropylene Film 0.15 parts of 2,6-ditertiary butyl paracresol and calcium stearate of 0.1 part with respect to 100 parts by weight of polypropylene resin powder (Hipol F657P manufactured by Mitsui Petrochemical Co., Ltd.). 1 part and the additives shown in Table 5 were added, mixed for 1 minute with a super mixer, and then melt-mixed at a kneading temperature of 230 ° C. using a uniaxial extruder to form pellets. A raw film is prepared by T-die molding using these pellets, and then stretched 5 times in the machine direction and 10 times in the transverse direction using a biaxial stretching machine to obtain a biaxially stretched film having a thickness of 25 μm. It was

The following tests were conducted on the obtained film, and the results are shown in Table 5. Haze: Automatic digital haze meter N manufactured by Nippon Denshoku Co., Ltd. based on JIS K-6714
It was measured by DH-20D. Blocking property: Two films are stacked and 200 g / c
After a load of m ² was applied and the mixture was allowed to stand at 40 ° C. for 24 hours, the peelability of the film was evaluated as follows. ◎ Peeling without resistance ○ Slightly difficult to peel △ Hard to peel × Extremely hard to peel Fisheye: Film 400c under an optical microscope
It is shown by the number of 0.1 m / m or more in m ² . Scratchability: It was shown as follows depending on the degree of scratching when two films were stacked and rubbed with fingers after 5 hours from film formation. ◎ Hardly scratched ○ Slightly scratched △ Slightly scratched × Scratched

[0061]

[Table 5]

(Application Example 2) Application to unstretched polypropylene film: 0.15 parts of 2,6 di-tert-butyl paracresol, 0.1 part of calcium stearate and 100 parts by weight of polypropylene resin powder and the additives shown in Table 6 Were added, and mixed for 1 minute with a super mixer, and then melt-mixed at a kneading temperature of 230 ° C. using a uniaxial extruder to form pellets.
Using this pellet, a non-stretched film having a thickness of 25 μm was formed by T-die molding at the same temperature. The obtained film was evaluated in the same manner as in Application Example 1, and the results are shown in Table 6.

[0063]

[Table 6]

Application Example 3 Application to Polyethylene Film Shown in a mixture of linear low density polyethylene having an MI of 1.3 / 10 min and a density of 0.92 and low density polyethylene having an MI of 1.1 / 10 min and a density of 0.93. The sample shown in 7 was added, melt-mixed at a temperature of 180 ° C. in an extruder, and then pelletized. Next, the pellets were fed to an extruder and inflation-formed into a film having a thickness of 30 μm, and the obtained film was evaluated in the same manner as in Application Example 1 and the results are shown in Table 7.
It was shown to.

[0065]

[Table 7]

(Application Example 4) Application to thermal recording paper Using the samples shown in Table 8, a thermal recording layer-forming liquid having the following composition was prepared, and No. The coating amount was 7 g / m ² using an 8 bar coater, and after air drying, it was 5 kg / m ^2.
A thermosensitive recording paper was prepared by calendering at a pressure of m ² . Dye Slurry 10 parts Developer Slurry 20 parts Sensitizer Slurry 20 parts Binder 15 parts Sample 20 parts Next, using NTT FAX-510T, Test Chart No. of IEICE. The thermal recording paper is colored by copying 1 and the color density is changed to DENSITOMETE.
It was measured using R FSD-103 (manufactured by Fuji Photo Film). The non-colored part was also measured in the same manner and displayed as background stain. Furthermore, the residue adhesion test is NEC PC-PRIOI
The ink ribbon of the TL Japanese color thermal transfer printer was removed, and the adhesion state of dust on the thermal head was observed when printing solid black on the thermal recording paper for test, and evaluated as follows. ◎ None at all △ Slightly adhered ○ Slightly present × Poor adhesion The results are shown in Table 8.

[0067]

[Table 8]

Application Example 5 Application to Inkjet Paper 10 g of the sample shown in Table 9 (110 ° C. dry standard) was used as a binder with polyvinyl alcohol (PVA 117 manufactured by Kuraray Co., Ltd.).
25 g of a 15% aqueous solution of 1) was added, and water was further added to make the total amount 60 g, and the mixture was sufficiently stirred and dispersed by a stirrer to prepare a coating liquid. This coating liquid was applied to a base paper (using PPC paper) having a basis weight of 45 g / m ^{2 so} that the coating amount was 10 g / m ² to obtain a recording paper. Next, the recording paper thus obtained was connected to a personal computer (PC-9801 manufactured by NEC Corporation), and an inkjet color image printer (Sharp
10-0700 manufactured by Co., Ltd. to obtain a hard copy recording paper having a test pattern. The image surface printed on the obtained hard copy test paper in four hues of black (IN-0011), magenta (IN-0012), cyan (IN-0013), and yellow (IN-0014) was subjected to an ultraviolet lamp (253.7). nm, GL-15 manufactured by Tokyo Shibaura Electric Co., Ltd.), the distance between the lamp and the test piece was set to 10 cm, irradiation was performed for 14 hours, and the fading degree of the test piece was visually compared and evaluated according to the following criteria. The results are shown in Table 9.

[0069]

[Table 9] ◎ Compared to before irradiation, there is almost no fading and image clarity is maintained. ○ A little discoloration is seen compared to before irradiation, but the sharpness of the image is still maintained. △ Fading was observed compared to before irradiation, and the sharpness of the image was lost. × The degree of fading is much higher than before irradiation.

(Application Example 6) Application as a matting agent for paint Acrylic urethane paint (Kanpe Co., Ltd. Deep Black #
400) and the sample shown in Table 10 was dispersed in a high speed homomixer (2500 rpm) for 5 minutes, and then coated on a glass plate with a film applicator of 5 Mil to a film thickness of 150 μm to obtain 60 ° specular reflectance and smoothness. (Spots) and scratch resistance were measured. The results are shown in Table 10. Regarding the scratch resistance, the state of scratches when rubbed with a coin was observed and shown as follows.

[0071]

[Table 10] ○ Almost no scratch △ Slightly scratched × Very scratched

Application Example 6 Application to Powder Foundation Using the sample obtained in Example 1, a powder foundation was prepared according to the following formulation. Component (A) Mica 38 parts Talc 10 parts Titanium dioxide 18 parts Coloring pigment 5 parts Spherical silica (Example 1) 15 parts Component (B) Squalene 5 parts Lanolin 4 parts Isopropyl myristate 3 parts Surfactant 1 part Perfume proper amount component The mica (A), talc, titanium dioxide, color pigment, and spherical silica were weighed out in parts, put into a stainless steel container, mixed well, and then pulverized with an atomizer. Then, the mixture was thoroughly mixed with a Henschel mixer, and the heated mixture of the component (B) was added thereto and thoroughly mixed to obtain a product. Randomly asked 10 people from 30 to 50 years old the obtained foundation and the foundation not containing spherical silica and compared and tested. Generally, the one using spherical silica has good elongation, and it may have a smooth and refreshing finish. Do you get it.

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph (10000 times) showing the particle structure of fine particle spherical silica obtained in Example 1 of the present invention.

FIG. 2 is a volume-based particle size distribution curve of the fine particle spherical silica obtained in Example 1 of the present invention.

FIG. 3 is a number-based particle size distribution curve of the fine particle spherical silica obtained in Example 1 of the present invention.

FIG. 4 is a conceptual diagram of a combination of fine particle spherical silica and an acrylamide polymer.

FIG. 5 is a scanning electron microscope photograph at 10000 times showing the particle structure of fine particle spherical silica obtained in Example 4 of the present invention.

FIG. 6 is a scanning electron microscope photograph at 10000 times showing the particle structure of fine particle spherical silica obtained in Example 14 of the present invention.

FIG. 7 is a scanning electron microscope photograph at 10000 times showing the particle structure of fine particle spherical silica obtained in Example 17 of the present invention.

FIG. 8 shows a particle structure of the silica powder obtained in Comparative Example 10
It is a scanning electron microscope photograph at a magnification of 000.

FIG. 9 shows the particle structure of the silica powder obtained in Comparative Example 10
It is a scanning electron microscope photograph at a magnification of 000.

FIG. 10 shows a particle structure of the silica powder obtained in Comparative Example 3.
It is a scanning electron microscope photograph at 10000 times. 1

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C09D 5/00 PNY 175/16 PHP D21H 19/38

Claims (11)

[Claims] 1. An alkaline silicate aqueous solution, an acrylamide polymer, and a partially neutralized acid aqueous solution are mixed, and the mixed solution is allowed to stand to produce a granular material consisting of a partially neutralized alkali silicate. A method for producing granular amorphous silica, characterized in that the particulate matter is separated and then neutralized 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 acrylamide polymer is 10,000 to 30.
The production method according to claim 1, which is an acrylamide polymer having a viscosity average molecular weight of 0,000. 4. The acrylamide polymer has 0.2 to 50 mmol / 10 of carboxyl groups in free or salt form.
The method according to claim 1, wherein the concentration is 0 g. 5. The method according to claim 1, wherein the acid is sulfuric acid. 6. The method according to claim 1, wherein the alkali silicate is present as SiO ₂ in the mixed solution at a concentration of 3 to 9% by weight. 7. The method according to claim 1, wherein the acrylamide polymer is added in an amount of 5 to 100% by weight based on SiO ₂ . 8. The method according to claim 1, wherein the acid is added during the partial neutralization so that the pH of the mixed solution becomes 10.2 to 11.2. 9. A BET specific surface area of 100 to 800 m ^2.
/ G and an amorphous silica which is the true represented by the whole clear spherical particles, and the ratio of the particles of the major axis (D _L) and the minor axis _{(D S) (D S /} D L) Sphere 0.90 to 1.00
Of 80% or more of the particles, and in the formula D ₂₅ / D ₇₅ , D ₂₅ represents the particle size of 25% of the volume-based cumulative particle size distribution curve by the Coulter counter method, and D ₇₅ is 75 Represents the particle size in%. Amorphous silica spherical particles having a sharpness of the particle size distribution defined by 1. 2 to 2.0 and a refractive index in the range of 1.46 to 1.50. 10. The amorphous silica spherical particles according to claim 9, which have a primary particle diameter of 0.3 to 30 μm as determined by scanning electron microscopy. 11. Apparent specific gravity (JISK-6220 method)
10. The amorphous silica spherical particles according to claim 9, wherein the content is 0.05 to 0.49 g / ml .