JPH01317115A - Silica sol having long and thin particle form and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject sol exhibiting excellent film-forming property when dried on a solid surface by adding an aqueous solution containing a water-soluble Ca salt or Mg salt to an colloidal aqueous solution of active silicic acid, adding a specific alkali metal compound to the solution and heating the mixture. CONSTITUTION:An aqueous solution containing a water-soluble Ca salt and/or Mg salt is added to a colloidal aqueous solution of active silicic acid of pH2-4 having an SiO2 content of 1-6wt.%. The weight ratio of the Ca or Mg compound to SiO2 is 1,500-3,500ppm in terms of CaO or MgO. The obtained aqueous solution is mixed with an alkali metal hydroxide, a water-soluble organic base or their water-soluble silicate at a molar ratio (SiO2/M2O) of 20-200 and heated at 60-150 deg.C for 0.5-40hr to obtain a stable alkaline aqueous silica sol having an SiO2 concentration of 1-6wt.% and composed of amorphous colloidal silica particles having thin and long shape with particle diameter ratio (D1/D2) of >=5 (D1 mmu is particle diameter measured by dynamic light-scattering and D2 mmu is particle diameter measured by N2 gas adsorption), D1 of 40-300mmu and uniform thickness falling within 5-20mmu by electron microscopy and extending along only one plane.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a novel silica sol and a method for producing the same. More specifically, this new silica sol is
The shape of the colloidal silica particles is characteristic, and when dried on a solid surface, it exhibits excellent film properties and is used in various fields including paints.

(Prior Art) Silica sol generally has the property of changing from a low viscosity state to a high viscosity state and finally turning into a gel. Therefore, if the SiO2 content is the same, a low viscosity product is evaluated to be more stable than a high viscosity product. In addition, silica sol is
The closer the shape of the colloidal silica particles contained therein to pearls, the lower the viscosity. For this reason, there have been many proposals for improving the efficient production of sols made of spherical colloidal silica particles. There are no proposals to improve the performance of .

As for the shapes of conventionally known colloidal silica particles, three typical types are shown in the drawing attached to US Pat. No. 2,680,721. One of them is spherical as described above, as shown in Figure 1 of the same drawing, and the second is a non-spherical one with a ratio of the major axis to the minor axis of approximately 2 to 3, and is shown in Figure 2 of the same drawing. Shown at the bottom.

The third one is of an irregular shape as shown in the lower part of Figure 3 of the same drawing. This third amorphous particle is derived from a three-dimensional network formed by chains of smaller silica particles, as described in the '721 patent. The fragments produced by cutting are bundled as a result of particle growth.
When focusing on one particle, it has an elongated shape, but its elongation is not controlled so that it lies within the same plane.

The above-mentioned US Pat. No. 2,680,721 discloses a method for producing a silica sol made of spherical colloidal silica particles, in which a monovalent base is added to a spherical silica sol having a diameter of 5 millimicrons or more to adjust the pH to 7 to 10.5, and the absence of an electrolyte. discloses a method of heating at 160 to 300°C.

US Pat. No. 2,900,348 discloses that a gel produced by adding an acid to an aqueous solution of water glass is washed with water,
Add alkali to this gel to adjust the pH to 9-95, and then
Discloses a method of making silica sol by heating at 5-100°C. This method is called a peptization method, and the colloidal silica particles of the silica sol obtained by this method have the shape of the second or third type described above.

(Problem to be solved by the invention) A sol made of spherical colloidal silica with a particle size of 4 to 150 millimeters has high stability and is used in various fields of application, and it provides this good dispersibility. The spherical shape of the particles may, in some cases, cause cracks to form in coatings formed from this silica sol-containing composition, or may cause colloidal formation when drying a composition containing this silica sol and ceramic fibers. Migration of silica particles occurs, causing practical problems such as easy dusting on the surface of the dried product.

When such a problem occurs, it is attempted to improve the silica sol by adding another component, but it is not easy to achieve a sufficient improvement.

The silica sol obtained by the above-mentioned conventional peptizing method does not have sufficient stability, and in some cases, silica precipitates may occur during storage. Although the colloidal silica particles are non-spherical, they still cause the same problems that occur when using a silica sol made of spherical colloidal silica.

The present invention aims to provide a stable silica sol that exhibits improved performance by modifying the shape of colloidal silica particles, and further aims to provide a method for efficiently producing the improved silica sol. It is something.

(Means for Solving the Problems) The silica sol of the present invention has a concentration of SiO□ of 40% by weight or less and is stable. The shape of the amorphous colloidal silica particles dispersed in the liquid medium of this sol has a particle diameter D1 of 40 to 500 millimicrons measured by dynamic light scattering, and when observed using an electron microscope. These particles have a uniform thickness within the range of 5 to 40 millimeters and have a shape that is elongated only in one plane, and the degree of elongation is measured using the nitrogen gas adsorption method (hereinafter referred to as the BET method). It is characterized by an elongated shape in which the ratio DI/D2 to millimicrons is 5 or more, with the converted particle diameter D2 given by this particle formula measured by the above-mentioned millimicrons.

As for the sol of this invention, the shape of the colloidal silica particles is such that the diameter of the particles as observed by an electron microscope is 5 to 5.
20 millimicrons, the particle size according to dynamic light scattering method is 40 to 300 millimicrons, and /D2
is 5 or more, first, the following (a)
, (b) and (C) steps: (a) Contains 1 to 6% by weight as S102, and has a pH of
An aqueous solution containing a water-soluble calcium salt, a magnesium salt, or a mixture thereof is added to a colloidal aqueous solution of activated silicic acid having an active silicic acid of 2 to 5.
Weight ratio 1500 to 850 as OlMgO or both
Step of adding and mixing an amount of 0 ppm, (bl A step of adding and mixing the silica content derived from activated silicic acid and the silica content of the silicate, and M represents the alkali metal atom or organic base molecule so that the molar ratio is 20 to 200; and (cl) The mixture obtained by step (b) is
It can be efficiently obtained by a manufacturing method characterized by including a step of heating at 250°C for 05 to 40 hours.

Furthermore, as the sol of the present invention, the size of the colloidal silica particles is larger than the above-mentioned size, that is, the diameter of the particles observed by an electron microscope is 5 to 4.
0 millimicrons, the particle diameter measured by dynamic light scattering is 40 to 500 millimicrons, and /D2 is 5 or more, first, the following (a'),
Steps (b') and (a'): (a') An acidic aqueous solution containing colloidal silica with an average particle size of 3 to 30 millimicrons in an amount of 05 to 25% by weight as SiO2 and having a pn of 1 to 5. silica.

An aqueous solution containing a water-soluble calcium salt, a magnesium salt, or a mixture thereof is added to the acidic sol.
0.1 as CaOlMgO or both for O2
5 to 1.00% by weight of an alkali metal hydroxide, a water-soluble organic base, or a water-soluble silicate thereof to the liquid obtained in the (b'lfa') step. M2o (However, SiO2 represents the silica content derived from the acidic silica sol and the silica content of the silicate, and M represents the alkali metal atom or molecule of the organic base.) so that the molar ratio is 20 to 300. (c') The mixture obtained by (b') is added to the
It is efficiently produced by a method that includes a step of heating at 300°C for 0.5 to 40 hours.

The shape of the colloidal silica particles constituting the sol of the present invention can be seen in photographs taken using an electron microscope. A large number of colloidal silica particles present in this sol are not limited to the same shape, but have an elongated shape in common. This large number of colloidal silica particles is
They are roughly divided into four types: straight, curved, branched, and ringed, but it is difficult to express their fractions in exact numbers. However, according to the photographs, the proportion of curved and branched plants is highest, and these types make up the majority.

Focusing on a single particle, the particle has a substantially uniform thickness from one end to the other. This almost uniformity is due to the sol manufacturing conditions, and the thickness also changes depending on the sol manufacturing conditions and is determined according to the empirical rules of manufacturing. A large number of colloidal silica particles in a sol produced using a certain method have a nearly constant thickness. The thickness of the colloidal silica particles of the sol obtained by the production method of the present invention is within the range of 5 to 40 millimeters. However, the length of many colloidal silica particles in a sol produced by a certain method is not constant. However, according to the photograph, the length is more than three times the thickness, and the majority of particles are usually several to several tens of times as long.

The above-described elongated colloidal silica particles constituting the sol of the present invention have yet another feature. That is, this elongated extension lies in the same plane. Even if they are bent or branched, they have elongation in the same plane, so even if all particles have different shapes, as long as they do not overlap, there will be a particle with the same thickness as these particles in the same plane. It can be laid down at the desired height. In an electron microscope photograph of the colloidal silica particles of the sol of the present invention, these elongated colloidal silica particles usually overlap, making it difficult to distinguish between one end and the other end of a single particle. Difficult to measure length. Furthermore, in the photograph, it is difficult to determine whether or not there is elongation of the particles in a direction perpendicular to the plane, that is, in a three-dimensional direction. However, when this three-dimensional extension exists, the silica sol becomes
The sol of the present invention is a stable medium-viscosity liquid, although it exhibits properties peculiar to the presence of a three-dimensional network structure or a structure close to it, such as significantly high viscosity or non-flowability, and is unstable.

Therefore, the colloidal silica particles constituting the sol of the present invention have no elongation in three-dimensional directions. The elongation within the same plane, which is a characteristic of the shape of the colloidal silica particles constituting the sol of the present invention, does not mean elongation within the same plane that is purely mathematically strict. Rather, 3
This is meant by the fact that it does not exhibit the characteristics exhibited by silica sol having a dimensional network structure or a structure close to it.

It is inappropriate to express the size of the colloidal silica particles constituting the sol of the present invention by the length estimated from the photograph (it is not appropriate to express the size by the length estimated from the photograph). It is appropriate to express it as a value measured by light scattering method.

As measured by this dynamic light scattering method, the size of the colloidal silica particles constituting the sol of the present invention is 40 to 40.
It is 500 millimicrons. This dynamic light scattering method for measuring particle size is described in the Journal of Chemical Physics.
ysicsl, Vol. 57, No. 11 (December 1972), p. 4814, for example, commercially available
The particle size can be easily measured using a device called N4 manufactured by Ulter. The specific surface area Srn'/g or D2 mμ measured by the normal BET method is the same as the specific surface area of elongated colloidal silica particles.
It means the diameter of a hypothetical spherical colloidal silica particle having r11''/g. Therefore, the particle diameter measured by the above dynamic light scattering method, mg, and the above D2 mu, /D2 is an elongated shape. refers to the degree of elongation of colloidal silica particles, and the silica sol of the present invention has this D
The value of 2 is 5 or more. However, the colloidal silica particles of the sol of the present invention usually have a specific surface area S of 4
Since it has a value of about 5 to 450 mF/g, the value of D2 is calculated to be 6 to 60 mμ using the above formula.

The colloidal silica particles of the sol of the present invention usually have an elongation value of 30 or less, expressed as /D2.

The colloidal silica particles constituting the sol of the present invention usually contain a small amount of Si due to the sol manufacturing method.
It contains calcium or magnesium oxides or both at a weight ratio of about 1,500 to 110,000 pp with respect to O2, and is substantially made of amorphous silica. In some cases, in addition to the oxides of calcium or magnesium, or both, a small amount of oxides of other polyvalent metals may be contained. The total amount of these calcium oxides, magnesium oxides, etc. and polyvalent metal oxides other than these is about 1500 to 15000 ppm by weight relative to SiO2 in this sol. The polyvalent metals other than calcium and magnesium include Sr, Ba, Zn, Sn,
II such as Pb, Cu, Fe, Ni, Co, Mn, etc.
Examples include valent metals, 111-valent metals such as Aj2, Fe, Cr, Y, and Ti, and IV-valent metals such as Ti, Zr, and Sn.

The silica sol of the present invention usually contains up to 40% by weight, preferably from 5 to 30% by weight of SiO2. The viscosity of this sol increases as the content of SiO2 in the sol increases;
It is about ~50[]cp. This sol is extremely stable and does not cause silica precipitation during storage.
No thickening occurs. Furthermore, the medium of this sol may be water, an organic solvent, or a solution of a water-soluble organic solvent and water. Both an aqueous sol, in which the medium is water, and an organosol, in which the medium is an organic solvent, are active due to the silanol groups present on the surface of the colloidal silica particles, and eventually irreversibly transform into a gel as the medium is removed. The organic solvent that is the medium for the organosilica sol may be any ordinary solvent that does not inhibit the activity of the colloidal silica particles, such as alcohols such as methanol, ethanol, isopropanol, butanol, and polyhydric alcohols such as ethylene glycol. Examples include ethers such as dimethyl ether and monomethyl ether of ethylene glycol, hydrocarbon solvents such as toluene and xylene, dimethylacetamide, dimethylformamide, and others.

The silica sol of the present invention, whose colloidal silica particles have a thickness of 5 to 20 millimicrons and a particle diameter of 40 to 300 millimicrons as measured by dynamic light scattering, is as described above (a), By going through the steps (b) and (c), an alkaline aqueous silica sol is first obtained.

The colloidal aqueous solution of activated silicic acid used in step (a) is a liquid in which silicic acid and polymer particles of silicic acid having a particle size of less than 3 millimicrons coexist, and can be easily obtained by a known method. A preferable colloidal aqueous solution of activated silicic acid is a water-soluble silicate, for example, a diluted aqueous solution of water glass having a molar ratio of about 1 to 45 (5j02/M20 (where M represents an alkaline earth atom)) is subjected to cation exchange treatment. obtained by
Usually 6% by weight or less, preferably 1 to 6% by weight of SiO□
and has a pH of 5 or less, preferably 2 to 5. This pH can be obtained by leaving some of the cations in the water glass aqueous solution during cation exchange treatment, or by removing all or part of the cations. It can also be easily adjusted by adding a small amount of an alkali metal hydroxide, a water-soluble organic base, etc. to the colloidal aqueous solution of activated silicic acid. Since this colloidal aqueous solution of activated silicic acid is unstable and tends to gel, it is preferable that it contains as few impurities as possible that would promote gelation, and it is preferable that it be immediately prepared.

A more preferred colloidal aqueous solution of activated silicic acid is SiO2/
It is obtained by passing a dilute aqueous solution of sodium water glass, a commercially available industrial product, with a Na2O molar ratio of about 2 to 4 through a hydrogen type cation exchange resin layer. As long as the sol targeted by the present invention can be obtained, this colloidal aqueous solution of activated silicic acid can be used as follows:
It may contain other components, and may contain trace amounts of cations, anions, etc.

(In the al step, a water-soluble calcium salt, magnesium salt, or a mixture thereof is added to the colloidal aqueous solution of activated silicic acid, preferably as an aqueous solution thereof.

The amount of the calcium salt, magnesium salt, or mixture thereof to be added is 1500 to 85 [10 pp] by weight relative to SiO□ in the colloidal aqueous solution of activated silicic acid.
m. In addition, this addition is preferably carried out under stirring, and there are no particular restrictions on the mixing temperature and time;
It may take about 5 to 30 minutes at 0°C. Examples of calcium and magnesium salts that may be added include inorganic and organic acid salts of calcium or magnesium, such as chlorides, nitrates, sulfates, sulfamates, formates, acetates, and the like. These calcium salts and magnesium salts may be used as a mixture.6 The concentration of the aqueous solution of these salts to be added is not particularly limited and may be about 2 to 20% by weight. When a polyvalent metal component other than calcium and magnesium is contained in the colloidal aqueous solution of activated silicic acid together with the calcium salt, magnesium salt, etc., a sol can be produced more preferably. Examples of polyvalent metals other than calcium and magnesium include Sr, Ba, Zn, Sn, and A.
I2, Pb, Cu, Fe, Ni, Co1. Mn,
Examples thereof include II-valent, III-valent, or TV-valent metals such as Cr, Y, Ti, and Zr. The amount of these polyvalent metal components is as follows: (When the amount of calcium salt, magnesium salt, etc. added in the al process is converted into the amount of CaOlMgO, etc., it is 10 to 80% by weight as polyvalent metal oxide relative to these CaOlMgO, etc.) degree is preferred.

If the polyvalent metal content remains in the colloidal aqueous solution of activated silicic acid obtained by subjecting the diluted water glass solution to the cation exchange treatment, the polyvalent metal content can be converted into oxides as described above. It is counted as part of 10 to 80% by weight. The remaining polyvalent metal component is preferably added as a water-soluble salt of the polyvalent metal to the colloidal aqueous solution of activated silicic acid together with the calcium salt, magnesium salt, etc. to be added. Preferred examples of this polyvalent metal salt include chloride, nitrate,
Examples include inorganic acid salts and organic acid salts such as sulfate, sulfamate, formate, and acetate. Also, zincate, stannate,
Salts such as aluminates, leadates, and the like, such as sodium aluminate and sodium stannate, can also be used.

The above-mentioned calcium salt, magnesium salt, polyvalent metal salt, etc. to be added are preferably mixed uniformly with the colloidal aqueous solution of activated silicic acid, and are usually added as an aqueous solution.

(In the bl step, an alkali metal hydroxide, a water-soluble organic base, or a water-soluble silicate thereof is added to the aqueous solution obtained in the above step (a).
It is preferable to carry out the step as soon as possible after the completion of the + step and under stirring. Further, there are no particular restrictions on the temperature and time of this mixing, and it may be about 5 to 30 minutes at 2 to 50°C. The alkali metal hydroxide, water-soluble organic base or water-soluble silicate thereof added is preferably homogeneously mixed with the aqueous solution obtained by step fa) and is added directly or as an aqueous solution. Examples of the alkali metal hydroxide include hydroxides of sodium, potassium, lithium, and the like. Examples of the organic base include quaternary ammonium hydroxides such as tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, and tetramethylammonium hydroxide, monoethanolamine, jetanolamine, triethanolamine, N,
N-dimethylethanolamine, N-(β-aminomethyl)ethanolamine, N-methylethanolamine,
Examples include amines such as motuprobanolamine and morpholine, and other basic nitrogen atom-containing organic compounds. In addition, those water-soluble silicates include sodium silicate,
Examples include potassium silicate, the above-mentioned quaternary ammonium silicate, and the above-mentioned amine silicate. Furthermore, aluminates, stannates, zincates, leadates, etc. of alkali metals or organic bases can also be used. These alkali metal hydroxides, organic bases, silicates, metal salts, etc. may be used in combination.

The amount of the alkali metal hydroxide, organic base, or water-soluble silicate thereof to be added is:
(a) The total amount of silica derived from the activated silicic acid used in the step and the silica of the silicate is 20 to 200 mol, preferably 60 to 100 mol, in terms of M2O per 1 mol of SiO. It's the amount. This addition causes the liquid to show p+ (about 7 to 10).

(In step C1, the mixture obtained in step (b) above is heated. This heating is performed at 60 to 250°C, but the pH of the colloidal aqueous solution of activated silicic acid used in step (a) is 2 to 4. When , this heating temperature is 60~
A range of 150°C is appropriate, and (if the pH of the colloidal aqueous solution of activated silicic acid used in the al step exceeds 4 and 5
If the heating temperature is below, the heating temperature is allowed to be even higher, ie up to 250°C. The heating time is about 0.5 to 40 hours, and the heating is preferably carried out while stirring the mixture, and preferably carried out under conditions that prevent water evaporation.

By this heating, particles in the liquid have an almost uniform thickness within the range of 5 to 20 millimeters and elongate only in one plane, and have a particle size of 40 to 300 mm by dynamic light scattering. Colloidal particles of silica with an elongated shape of millimicrons are produced.

Therefore, the obtained liquid is a sol, but the SiO2 concentration is
Usually, it is about 1 to 6% by weight and contains a large amount of anions. This sol is usually further concentrated, but if present in a concentrated sol with a SiO2 concentration of 10 to 30% by weight, anions of an amount or more that would interfere with the stabilization of the sol (
It is preferable to remove it from the sol obtained in the cl step. At the time of this removal, it is preferable to also remove part of the water in the sol. When some of the water is removed from the sol, the S in the sol
Since the iO2 concentration increases, the amount of water removed is
It is preferable to set the amount to such an amount that a sol having an O□ concentration of 30% by weight or less can be obtained. (As a method for removing water and anions together from the sol obtained by the cl step, it is preferable to remove them using a normal microporous membrane, such as an ultrafiltration membrane. Another method for removing the sol includes an ion exchange method using an ion exchange resin, etc. After removing the amount of anions that interfere with the above-mentioned stabilization, the sol can be concentrated by an evaporation method or the like. The sol obtained in step (C) or the sol after concentration may be subjected to pn adjustment by appropriately adding an alkali.

The sol from which the above anions and water have been removed has a SiO2 concentration of 10
~30% by weight, has a viscosity of several cp to about 500 cp at room temperature, and exhibits a pH of 8.5 to 11. This sol contains anions of less than 000 ppm, usually 200 ppm.
Although it contains ~800 ppm, it is extremely stable.

In addition, this sol contains alkali metal ions, organic bases, etc. in an amount such that the molar ratio of SiO2/M20 (where M is the same as above) is 20 to 200, and further contains calcium ions, magnesium, or these and the polyvalent metals. 1500-15000p for SiO2 in terms of those oxides
Contains approximately pm. The colloidal silica particles in this sol maintain the shape and size already formed in step (C), and the colloidal silica particles in the sol retain the shape and size already formed in the step (C), and
Or it contains these and a polyvalent metal oxide. These chemical analyzes can be easily performed by conventional methods.

The dynamic light scattering particle diameter of this colloidal silica particle is easily measured by a commercially available device, and is 40 to 300 millimicrons.

The sol obtained by the above method of the present invention ultimately irreversibly turns into a gel by removing water. This sol is an alkaline aqueous sol, but if it is subjected to cation exchange treatment, an acidic aqueous silica sol can be obtained, and by adding another alkali to this, another alkaline aqueous silica sol can be obtained. can. This acidic aqueous silica sol preferably has a pH of 2 to 4. Further, from these acidic aqueous sols, an aqueous sol consisting of positively charged colloidal silica particles can be obtained by a conventional method. Furthermore, organosols can be obtained from these aqueous sols by replacing water in the medium with an organic solvent by a conventional method such as a distillation displacement method. In all of these acidic aqueous sols, aqueous sols consisting of positively charged particles, and organosols, the colloidal silica particles retain the shape already formed in step (c),
Removal of the medium eventually irreversibly transforms into a gel.

Alkaline aqueous silica sol, acidic aqueous silica sol,
For each type of positively charged silica sol, a stable sol can be obtained by mixing the same type of sol according to the invention with a conventional sol.

Regarding the organosol, if the solvents are compatible and the colloidal silica does not aggregate due to the solvent, a stable sol can be obtained by mixing the sol according to the present invention with a conventional sol.

The sol of the present invention can also be obtained by other methods. According to this second method, colloidal silica particles having a thickness of 5 to 40 millimicrons and a particle diameter of 40 to 500 millimicrons determined by dynamic light scattering are obtained. This second method is as described above.
It consists of steps a'l, (b'l and (C')) and is advantageous for producing particles with large diameters.

The average particle diameter used in the step (a') is 3 to 30 millimicrons, the SiO2 content is 05 to 25% by weight, and the pH is 1.
The acidic aqueous silica sol of 5 to 5 may be produced by any conventionally known method, for example, the method described in the specifications of U.S. Pat. No. 268,071, U.S. Pat. Particle diameter D2 calculated from the particle diameter measured by the light scattering method and the specific surface area measured by the BET method
As long as the value of the ratio n+/D2 is less than 5, the shape of the colloidal silica particles may be spherical or non-spherical.

However, it is preferable to use a sol of spherical colloidal silica particles in order to make the thickness of the produced particles uniform along their length.

(a′l, (b′l and (C′)) of this second method
In the step, the same operations as in the steps (al, (bl) and (c) above are used. However, in the step (a'), the amount of CaOlMgO or both added is 1% to the SiO□ of colloidal silica. In step (b'), the amount of alkali metal hydroxide, water-soluble organic base, or water-soluble silicate thereof added is reduced by 300% as SiO□/M20 molar ratio. In step (C'), the heating temperature was set to 300
It can be raised up to ℃.

By concentrating the sol obtained through steps (a'l, (b'l and (C')) in the same manner as above, an anion concentration of 0.1% by weight or less and Si
A stable alkaline aqueous silica sol with an O2 concentration of 1 to 40% by weight can be obtained. Furthermore, acidic sol, positively charged silica sol, organosol, mixed sol, etc. can also be obtained in the same manner as above.

(Function) The colloidal silica particles of the sol of the present invention are elongated and have a thickness within the range of 5 to 40 millimicrons, and have a uniform thickness and are distributed only in one plane at the above-mentioned DI102 value of 5. The elongated shape with the above elongation and a particle size measured by dynamic light scattering of 40 to 500 millimicrons is due to the sol manufacturing method of the present invention. Although it is difficult to fully elucidate the mechanism of production of colloidal silica particles, it is thought to be as follows.

First, when a water-soluble salt of calcium or magnesium or a mixture thereof is added to a colloidal aqueous solution of activated silicic acid in the (aj step), calcium ions, magnesium ions, etc. are captured by particles of activated silicic acid.
When alkali metal hydroxides, organic bases, silicates of these, etc. are added in the BL process, some of the activated silicic acid particles that have captured calcium ions, magnesium ions, etc. aggregate in a string, resulting in bending in arbitrary directions. Elongated filamentous aggregate particles are produced. These filamentous aggregate particles are -
It does not have to extend only within a plane, or it may partially form a three-dimensional network structure. and (c
) When heated in the step, polymerization of the activated silicic acid particles occurs, cutting of the long thread-like particles and destruction of the three-dimensional structure, resulting in a length of approximately 10 to 10 mm.
Fragments with a length of approximately 0 millimicrons are generated, and calcium ions, magnesium ions, etc. that have already been captured on these fragments and short particles act to cause the elongation of these fragments and short filamentous particles. Fixed so that it exists only in one plane. Continuation of the heating in step (C) causes the dissolved silicic acid in the liquid and the dissolved silicic acid eluted from the easily eluted portions of the fragmented threads to precipitate successively on the surface of the fragmented threads, thereby increasing the thickness of the fragmented threads.

As a result of this series of processes, [C) After the process is completed, the liquid has an almost uniform thickness within the range of 5 to 20 millimeters, has elongation only in one plane, and has a length of 15 to 200 millimeters. Colloidal silica particles with elongated shapes on the order of microns are generated.

Also when using the second manufacturing method of the present invention comprising steps (a'), (b'l and (C')), colloidal particles with a particle size of 3 to 30 millimicrons are used instead of the activated silicic acid fine particles. It is believed that silica particles act similarly.

(In the colloidal aqueous solution of activated silicic acid used in the al process,
After adding the aqueous solution of the alkali metal hydroxide, organic base or water-soluble silicate thereof used in step fb),
(When an aqueous solution of calcium salt, magnesium salt, or a mixture thereof used in the al process is added, gel formation occurs rapidly, and it is difficult to evenly disperse it using ordinary stirring means. However, the colloidal silica particles of the present invention having the above shape cannot be produced.

(In the al step, if the SiO□ concentration of the colloidal aqueous solution of activated silicic acid used is 1% by weight or less, a large amount of water must be removed during concentration, which is not efficient.

Furthermore, when the SiO2 concentration of this colloidal aqueous solution of activated silicic acid exceeds 6% by weight, the stability of this solution decreases significantly;
This makes it difficult to produce a sol of constant quality. Therefore, this SiO□ concentration is preferably 1 to 6% by weight;
is preferably from 2 to 5. When this pH is 5 or more, the stability of the aqueous solution of activated silicic acid is significantly reduced, and (c
) The colloidal silica particles of the sol obtained through the process are
It does not have the elongated shape described above. Although this pH may be 2 or less, it is not preferable because it not only requires the addition of an acid but also increases the amount of unnecessary anions.

In the fal step, uniform mixing can be easily achieved by adding a calcium salt, a magnesium salt, or a mixture thereof as an aqueous solution to this colloidal aqueous solution of activated silicic acid. This uniform mixing results in added calcium ions,
This is important for facilitating uniform capture of magnesium ions and the like by silicic acid.

(A colloidal aqueous solution of activated silicic acid used in the al step, which is obtained by subjecting an aqueous solution of a water-soluble silicate to a cation exchange treatment, contains almost no dissolved or free cations in the solution.

As the aqueous silicate used for this purpose, it is preferable to use water glass, which can be produced easily and inexpensively by hand.

Water-soluble silicates obtained by dissolving silica obtained by hydrolyzing silicon halide, alkoxysilane, etc. in an alkali have a low content of impurities, especially polyvalent metals, but are expensive. On the other hand, industrial water glass containing -S usually contains several thousand ppm or less of polyvalent metals in terms of oxides based on the silica content. Even if this water glass aqueous solution is subjected to cation exchange treatment, the entire amount of the polyvalent metal components cannot be removed. Therefore, in the colloidal aqueous solution of activated silicic acid obtained, polyvalent metal oxides usually remain in an amount of about 5,000 ppm or less. Because it is trapped, it does not exist in the liquid as a dissolved or free cation. This residual polyvalent metal component is included as part of the polyvalent metal component used together with calcium salts, magnesium salts, etc. in the step (a), and when added together with calcium salts, magnesium salts, etc. Acts similarly to metal salts.

(a) The amount of calcium salt, magnesium salt, or a mixture thereof added to the process is 1500 pp by weight as CaOlMgO or both with respect to SiO□ of active silicic acid.
If the amount is less than 8,500 ppm, the shape of the final colloidal silica particles will be spherical or cocoon-like, and on the other hand, if the amount is more than 8,500 ppm, the specially shaped colloidal silica particles of the present invention cannot be produced even after the step (C). . Therefore, this 1500-8500 pp weight of CaOlMgO
Alternatively, elongated particles having the above-mentioned directionality are thought to be produced by both of them. The polyvalent metal component used in combination with this calcium salt, magnesium salt, etc. has the effect of promoting or suppressing the production of colloidal silica particles depending on its type, but the amount thereof may be different for CaO, MgO, or both. When the amount is about 80% by weight or more in terms of oxide, gelation occurs in the colloidal aqueous solution of activated silicic acid.

After addition and mixing of calcium salts, magnesium salts, etc. in step 2 (a), add to the resulting solution as soon as possible so as not to cause any change in the active silicic acid particles in the solution.
Alkali metal hydroxides, organic bases or silicates thereof according to step Fb) are added. These alkaline substances are also added directly or as a 5 to 30% by weight aqueous solution, preferably under stirring, so as to facilitate uniform mixing.

(If the amount of these alkaline substances added in the bl step is 20 or less as the SiO□/M20 molar ratio, (C
) Particle growth does not occur due to heating in the Cl step, and on the other hand, if this molar ratio is 200 or more, gel-like material is generated without particle growth even when heated in the Cl step. /M20 molar ratio of 20 to 200, preferably 60 to 100, and by heating in the fcl step, colloidal silica particles having the size and shape targeted by the present invention can be produced. (The addition of the alkaline substance in the bl step is preferably carried out at as low a temperature as possible, preferably at room temperature, so that stirring can be performed easily.

(If the heating temperature in the C1 step is 60°C or lower, the colloidal silica particles that are the object of the present invention cannot be grown, and heating at 60°C or higher is necessary.
When the p)l of the colloidal aqueous solution of activated silicic acid used in the process is 2 to 4, gels tend to form if the heating temperature exceeds 150°C. In addition, when the p■ of the colloidal aqueous solution of activated silicic acid used in the step fa) is more than 4 and less than 5, this
The heating temperature in the fc) step may exceed 150°C, but
If the temperature is higher than 250°C, gel tends to form.

As long as a constant particle size is intended, the heating time may be shorter at a high temperature of 60° C. or higher; on the other hand, if the heating temperature is lower, a longer time is required. Therefore, it is preferable that the heating in the Cl step be carried out at 60 to 250°C for about 0.5 to 40 hours. (After the Cl step, the obtained sol is cooled. It can also be diluted with

Stability is an essential property for a sol as an industrial product, and a concentration of 10 to 30% by weight of SiO□ is usually desired. At this concentration, the concentration of anions that may be present in the sol to obtain a stable alkaline sol is usually 11,000 pp or less. Since ions of calcium, magnesium, and their valence metals are captured in the colloidal silica particles, they are not dissolved in the aqueous medium of the sol in an amount that would interfere with the stabilization of the sol. The above SiO□ concentration 1 concentration 1 note ~ 30/M20 (
M is the same as above. ) It is necessary to contain alkali cations in a molar ratio of about 20 to 200 in the sol. Due to these alkaline cations, the sol usually has a pH of 8.5~
11 is shown. When a microporous membrane is used to remove anions from the sol in step (c), the removal of cations also occurs, which may result in a shortage of alkaline cations remaining in the sol. In such a case, a stable sol can be obtained by further replenishing the sol with the necessary amount of the alkali metal hydroxide, organic base, etc. to stabilize the sol while concentrating it, or by replenishing it after concentration. is obtained. In a method using a microporous membrane such as an ultrafiltration membrane, since colloidal silica particles in the sol do not pass through the membrane, the sol is simultaneously concentrated as water flows out together with anions. This concentrated sol can optionally be diluted with water.

In the second production method according to the present invention, if the SiO2 concentration of the acidic sol used in step (a') is 0.5% by weight or less, it is necessary to remove a large amount of water when concentrating after step (C'). Not on point. Furthermore, if the SiO2 concentration is as high as 25% by weight or more, the amount of Ca salt, Mg salt, etc. added increases, and the sol to which these salts are added tends to gel, which is not preferable. When the pH of the acidic sol used in step (a') is below 1 or above 5, the stability of the sol becomes poor, and the colloidal silica particles in the sol obtained in step (C') have the elongated shape. I don't have it. Even if the particle size of the acidic sol used in step (a') is 30 millimicrons or more, the colloidal silica particles in the sol obtained in step (C') still do not have the elongated shape.

Silica sols with particle sizes less than 3 millimicrons may also be used;
Since the production method consisting of the above steps (al, [b) and (c) is much more efficient, usually (a')
No acidic silica sol with particle size less than 3 millimicrons is used in the process. The amount of calcium salt, magnesium salt, etc. added in step (a') can be increased compared to the amount added in step (a), but
．． If the amount exceeds 0.00% by weight, the elongated colloidal silica cannot be obtained in step (C').

The amount of alkaline substance added in step (b') is (
Although it is possible to reduce the amount added in step b), if SiO□/M20iO□ exceeds 300, a gel-like substance is likely to be formed in step (C').

The heating temperature in step (C') is allowed to be much higher than the heating temperature in step (c), but 300
At temperatures above 0.degree. C., gelation tends to occur, and the efficiency of the manufacturing process is not significantly improved. As expected, the higher the heating temperature, the shorter the heating time, if a constant particle size is intended;
At 00°C, the elongated colloidal silica particles can be efficiently produced by heating for 0.5 to 40 hours.

The silica sol produced by the second production method consisting of steps (a'), (b') and (C') also has an anion content of 11,000 at high SiO2 concentrations.
If it is higher than pp, the stability of the sol will be reduced. Also,
As an alkaline aqueous sol, SiO□/M20iO□
The presence of alkaline cations in an amount of 20 to 300 is necessary for stabilization, and especially when concentrating silica sol, the amount of anions and cations in these sol is necessary for stabilization. It is important to maintain this within a reasonable range. As long as this stability is maintained, the concentration of the sol will be (a
It can be carried out in the same way as the concentration method carried out after steps 1, (b) and FC).

(Example) Example 1 Commercially available JIS No. 3 sodium water glass (5in2/N
Water was added to the a2O molar ratio 3.22, S], O02 content 285% by weight) to obtain an aqueous sodium silicate solution with a SiO2 concentration of 36% by weight. By passing the above sodium silicate aqueous solution through a column packed with a cation exchange resin with the trade name Amberlite 120B prepared separately, SiO□ concentration was 356% by weight, pH was 2.81, and electrical conductivity was 731 μS/a.
A colloidal aqueous solution of active silicic acid of m was obtained. This liquid contains i
A total of 75 ppm of 203 and FezO3 remained.

2000 g of the above colloidal aqueous solution of activated silicic acid was put into a glass container, then 8.0 g of a 10% by weight aqueous calcium chloride solution was added at room temperature with stirring, and after 30 minutes, an additional 1
12.0 g of 0% by weight aqueous sodium hydroxide solution were added at room temperature with stirring. The resulting mixed solution had a pH of 7.6 and a 5io2/[a2o molar ratio of 80.

Next, the above mixture was charged into a stainless steel autoclave, heated at 130° C. with stirring for 6 hours, cooled, and the contents were taken out. The obtained liquid is a silica sol, and 5
Contains 3.52% by weight of iO2, SiO□/Na2O
The titration method molar ratio was 101 and the pH was 9.64, CaO was contained at a weight ratio of 5400 ppm to SiO2, and no free calcium ions were detected.

Next, the silica gel was concentrated using an ultrafiltration device to obtain a concentrated silica sol with a SiO2 concentration of 21% by weight. As a result of analysis, this concentrated sol does not contain any calcium ions or free calcium ions, has a specific gravity of 1.136, a pH of 9,
24, viscosity 125cp (20℃), 5iO9/
Na2O titration method molar ratio 126, CaO content 0.1
13% by weight, chloride ion content 0.019% by weight, sulfate ion content 0.0020% by weight, electrical conductivity 2080μS
/cm. The colloidal silica particles in this sol are
When observed using an electron microscope photograph, it was found that the particles were elongated and had a thickness of 12 mm. This sol had a colloidal silica particle diameter of 846 millimicrons as determined by dynamic light scattering. Further, the colloidal silica particle diameter was calculated from the BET method to be 12 millimicrons.

FIG. 1 of the accompanying drawings shows a photograph of colloidal silica particles in this sol taken with an electron microscope at a magnification of 200,000 times.

When this concentrated silica sol was stored at 60°C under closed conditions,
No deterioration was observed even after one month.

When this sol was applied onto a glass plate and dried, a better coating was formed than when using conventional sol. This coating did not dissolve in water even when it came into contact with water.

Example 2 Colloidal aqueous solution of activated silicic acid (Si02356
%, pH 2,81) in a glass container, add thereto 80 g of a 10 wt% aqueous calcium chloride solution with stirring, and then add 12.0 g of a 10 wt% aqueous sodium hydroxide solution with stirring. S
A mixed solution with an iOz/Na2O molar ratio of 80 and a pH of 7.62 was obtained.

This mixed solution was placed in a stainless steel autoclave container at 2.5°C, and heated at 130°C for 24 hours. The obtained silica sol contains 3.52% by weight of SiO2 and S
The iO□/Na2O titration molar ratio was 101, and CaO was contained at a weight ratio of 5400 ppm relative to SiO2.

The pH of this sol was 9.81.

This sol was concentrated to a silica concentration of 15.2% by weight using an ultrafiltration device. The obtained sol has a specific gravity of 1.092,
pH9.36, viscosity 225cp, SiO2/NaJ
Titration method molar ratio 185, CaO 820ppm,
([223ppm, SO424ppm, conductivity 162
The particle diameter was 145 mμ by BET method, and 167 mμ by dynamic light scattering method. This sol is 6
It was stable for 1 month at 0°C.

Example 3 Colloidal aqueous solution of activated silicic acid (SiO73,5
6%, pH 2,81) was placed in a glass container, 8.0 g of a 10% by weight aqueous calcium chloride solution was added thereto with stirring, and then 13.5 g of a 10% by weight aqueous sodium hydroxide solution was added with stirring. By doing so, SiO□/Na2O method molar ratio 70 and IIH7,8
A mixed solution of 4 was obtained.

This mixed solution was charged into a 2.5 liter stainless steel autoclave container, and heated at 100° C. for 6 hours. The obtained silica sol contained 5iO23,52% by weight, SiO2/
Na2O titration method molar ratio is 880, CaO is 5iO
It contained 5400 ppm compared to 7. The pH of the sol was 955.

This sol was filtered with a silica concentration of 206% by weight using an ultrafiltration device.
It was concentrated to The obtained sol has a specific gravity of 1.133, p
H9,21, viscosity 45cp, SiO□/Na2O titration molar ratio 10[1, CaO111Dppm, C
j2 265ppm, SSO435pp, conductivity 29
The particle size was 70 μS/cm, the BET method particle size was 88 μ, and the dynamic light scattering method particle size was 51.8 m+t. This sol is 6
It was stable for 1 month at 0°C.

Example 4 The commercially available sodium water glass aqueous solution of Example 1 was subjected to cation exchange treatment to obtain 1. SiO23.66% by weight
A colloidal aqueous solution of activated silicic acid having a pH of 2.82 was obtained.

2000 g of this colloidal aqueous solution of activated silicic acid was placed in a glass container, 1.08 g of a 952% by weight zinc chloride aqueous solution acidified with hydrochloric acid was added thereto with stirring, and then 12.0 g of a 10% by weight calcium nitrate aqueous solution was added with stirring. SiO2/Na2O
A mixed solution with a legal molar ratio of 70 and p) f7.82 was obtained.

This mixed solution was placed in a 2.5e stainless steel autoclave container and heated at 130° C. for 6 hours.

The obtained silica sol contained 3.61% by weight of SiO2 and had an SiO2/Na2O titration molar ratio of 88.0.
Weight ratio of CaO 5600 ppm and Zn0 to SiO□
It contained 890 ppm. The pH of the sol was 972.

This sol was filtered with a silica concentration of 218% by weight using an ultrafiltration device.
It was concentrated to The obtained sol had a specific gravity of 1142, a pH of 9,
37, viscosity 79cp, SiO2/Na2O titration molar ratio 123, CaO1220ppm, ZnO1
95ppm, CCl230pp, NO3345
ppm, contains SO424ppm, conductivity 2.40
The particle diameter was 0u 37 cm, the particle diameter was μ by BET method, Omμ, and the particle diameter was 626 mμ by dynamic light scattering method. This sol is 6
It was stable for 1 month at 0°C.

Example 5 A colloidal aqueous solution of activated silicic acid having 374% by weight of Si0□ and pH 2.85 was obtained by subjecting the aqueous solution of commercially available sodium water glass of Example 1 to a cation exchange treatment. 2000 g of this colloidal aqueous solution of activated silicic acid was placed in a glass container, and 76 g of a 10% by weight aqueous magnesium chloride solution was added thereto.
was added with stirring, and then 17.5 g of a 10% by weight aqueous potassium hydroxide solution was added with stirring to obtain a mixed solution with a SiO□/20 molar ratio of 80 and a pH of 7.39.

This mixed solution was placed in a 2512 stainless steel autoclave container and heated at 120° C. for 6 hours.

The obtained silica sol contained 5LO23.69% by weight, Si
20 titration method molar ratio to O□/ is 101, MgO is Si
It was contained in a weight ratio of 4390 ppm to O□. Sol's pn was 847.

To 1,564 g of this sol, 4.5 g of a 10-weight aqueous potassium hydroxide solution was added with stirring to adjust the pH to 9.53.

This sol was concentrated to a silica concentration of 16.2% by weight using an ultrafiltration device. The obtained sol has a specific gravity of 1.100, p
H9,20, viscosity 69cp, SiO2/K2020
Titration method ratio is 143, MgO 710ppm, fl
301ppm, SO459ppm, conductivity 3070μS/em, BET method particle size 11.1m
μ, dynamic light scattering particle diameter was 855 mμ. This sol was stable for one month at 60°C.

Example 6 Colloidal aqueous solution of activated silicic acid (SiO23,7
4% by weight, pH 2,85) was placed in a glass container, and 4% by weight of a 10% by weight aqueous magnesium chloride solution was added to it.
．． 8 g of monoethanolamine was added with stirring, and then 244 g of monoethanolamine was added with stirring to obtain a mixed solution with a SiO□/monoechnolamine molar ratio of 31 and a pH of 762.

This mixed solution was placed in a stainless steel autoclave container at 2.5°C and heated at 130°C for 6 hours.

The obtained silica sol contained 3.73% by weight of SiO□, 122% by weight of monoethanolamine, and a molar ratio of SiO□/monoethanolamine titration method of 365.
The weight ratio to O2 is 2820 ppm, and the pH is 90.
It was 0.

1.0 g of monoethanolamine was added to 1917 g of this sol with stirring to adjust the pH to 9.50.

This sol was concentrated to a silica concentration of 14.8% by weight using an ultrafiltration device. The obtained sol has a specific gravity of 1.091,
pH 9.19, viscosity 33 cp, monoethanolamine content 0.362 wt%, SiO□/monoethanolamine titration molar ratio 47, MgO content 417 ppm.
, conductivity 1670μS/cm, BET method particle size 1
The particle size measured by dynamic light scattering was 72.5 mu. It was stable for more than 6 months at room temperature.

Example 7 Commercially available JIS No. 3 sodium water glass (5iO229
2% by weight, Na209.47% by weight, SiO2/Na
2O molar ratio 318) was diluted with water to a silica concentration of 290% by weight, and passed through a column packed with a cation exchange resin to obtain Si.
A colloidal aqueous solution of activated silicic acid with an O2 concentration of 290% by weight and a pH of 2.85 was obtained. Residual Af2203 and Fe20a
The total amount was 26 ppm. 2000 g of the above colloidal aqueous solution of activated silicic acid was placed in a glass container, and 10
90 g of a wt % calcium nitrate aqueous solution was added with stirring, followed by 966 g of a 10 wt % aqueous sodium hydroxide solution.
was added with stirring, and the SiO□/Na2O molar ratio was 8o.
And so. pH was 7.56. Add this mixture to 2.5
Pour into a stainless steel autoclave container at 130°C.
The mixture was heated at C for 6 hours. The obtained silica sol is SiO2
2.87% by weight, SiO□/Na2O titration method molar ratio 1
13, and the weight ratio of CaO to SiO□ is 5300
ppm was included, and the pl of the sol was 967.

This sol was concentrated to a SiO2 concentration of 16.0% by weight using an ultrafiltration device.6 The resulting sol had a specific gravity of 1.098,
pH9.32, viscosity 70cp, 5iO316.0% by weight, SiO2/Na2O titration molar ratio 108,
Ca0850ppm, Cj230ppm, NN
O3313pp, SO422ppm, conductivity 1745
μS/cm, BET method particle size was 10.9 mμ, and dynamic light scattering method particle size was 69.3 mu. This sol was stable for one month at 60°C.

Example 8 The silica sol obtained in Example 1 with a silica concentration of 21.0% by weight was diluted with pure water to a silica concentration of 16% by weight, and passed through a column packed with a cation exchange resin to give a silica concentration of 15.7%.
A silica silicate sol of % by weight was obtained.

The obtained sol has a specific gravity of 1092, a pH of 2.20, and a viscosity of 13.
cp, Sin□15.7% by weight, Na2O190pp
m, CaO185ppm, C,i2144p
pm, SO416ppm, conductivity 3.030u
The particle size was 37 cm, the BET particle size was 12.0 mg, and the dynamic light scattering particle size was 846 mμ. This sol was stable for more than 3 months at room temperature.

Example 9 800 g of the acidic silica sol obtained in Example 8 was placed in a rotary vacuum concentrator, and the vacuum inside the container was set to 650-720 T.
While maintaining the liquid temperature at 20 to 40° C., 12.020 g of anhydrous methanol was added thereto over 14 hours, and water was azeotropically distilled off to replace water in the sol with methanol.

The obtained methanol silica sol had a specific gravity of 0876, a viscosity of 14.5 cp, and a SiO2 content of 14.3% by weight.
The H20 content was 1.0% by weight. This sol is at room temperature 3
It remained stable for over several months.

Comparative Example 1 Colloidal aqueous solution of activated silicic acid (SiO□3.5
6% by weight, pH 2,81) was placed in a glass container, and 12% by weight of a 10% by weight aqueous sodium hydroxide solution was added to the container.
．． 0 g was added with stirring to give a SiO2/Na2O molar ratio of 80. The pH was 7.8.

This mixed solution was placed in a stainless steel autoclave container at 2.5°C and heated at 130°C for 6 hours.

The obtained sol contained 3.54% by weight of SiO□, S1y□/
The Na2O titration molar ratio was 107 and the pH was 10.07. This sol was passed through an ultrafiltration device to a SiO2 concentration of 21.
It was concentrated to 9% by weight. The obtained sol has a specific gravity of 1.14
4, pH 9.69, viscosity 4.3 cp, SiO□21.
9% by weight, SiO□/Na2O titration method molar ratio 126, electrical conductivity 2140 μS/cm, BET method particle size 11.0
mμ, and the dynamic light scattering particle diameter was 26.8 mμ.

An electron microscope photograph of this sol is shown in FIG. 2, and the colloidal silica particles are spherical in shape.

Comparative Example 2 Water was added to the sodium water glass described in Example 1 to dilute it to a concentration of 50% by weight, resulting in 1500 g of this aqueous solution.
into a glass container, and add 10% sulfuric acid aqueous solution 380
g was added with stirring to bring the pH to 454.

The generated silica wet gel is filtered and added with pure water
000 g was poured and washed. By dispersing the obtained wet gel in pure water, the SiO2 concentration was 40% by weight.
1800 g of a dispersion was obtained. Add 12.0 g of a 10% by weight aqueous sodium hydroxide solution to this to form a SiO2/Na
The zO molar ratio was set to 80. pH was 9.0.

This dispersion liquid was charged into a stainless steel autoclave container at 2.5°C, and then heated at 130°C for 6 hours. The obtained sol contained 3.97% by weight of SiO□, SiO2/Na
The 2O titration molar ratio was 87 and the pH was 10.46.

This sol was concentrated to a silica concentration of 212% by weight using an ultrafiltration device. The obtained sol has a specific gravity of 1,138, p
H9.98, viscosity 40cp, SiO□21.2% by weight
, SiO□/Na2O titration molar ratio 98, conductivity 252
゜u 37cm, BET method particle size 9.9 mμ,
The dynamic light scattering method particle diameter was 912 mμ. This sol is
As shown in the photo taken with an electron microscope in Figure 3,
The colloidal silica particles are non-spherical but do not have an elongated shape.

Comparative Example 3 Colloidal aqueous solution of activated silicic acid (SiO2356
Weight %, pH 2,81) 2000 g was placed in a glass container, and a 10 weight % calcium chloride aqueous solution 8.0
SiO2
/Na2O molar ratio was set to 80. pn was 7.62. The weight ratio of CaO to SiO2 was 5400 ppm.

This mixed solution was placed in a stainless steel autoclave container at 2.5°C, and then heated at 160°C for 6 hours. As a result, a gel-like substance was formed in the container and showed no fluidity.

Comparative Example 4 Colloidal aqueous solution of activated silicic acid of Example 1 (Si02356
Weight %, pH 2,81) 2000 g was placed in a glass container, and 8.0 g of a 10 weight % calcium chloride aqueous solution was added to it.
was added with stirring, and then 3.8 g of a 10% by weight aqueous sodium hydroxide solution was added with stirring to obtain Sin□/
The Na2O molar ratio was set to 250. pH was 654.

The weight ratio of CaO to SiO2 was 5400 ppm.

This mixed solution was charged into a stainless steel autoclave container at 2.5°C, and then heated at 130°C for 6 hours. As a result, a gel-like substance was formed in the container and showed no fluidity.

Comparative Example 5 Colloidal aqueous solution of activated silicic acid of Example 1 (SiO□3.5
6% by weight, pH 2,81) was placed in a glass container, and a 10% by weight calcium chloride aqueous solution 16.
0g of SiO
2/Na2O molar ratio was set to 80. pH was 7.48. CaO has a weight ratio of 110,800p to SiO2
It was p.

In the above operation, the viscosity of this liquid mixture increased and the fluidity decreased 20 minutes after the start of addition of the aqueous sodium hydroxide solution. This paste-like material with reduced fluidity was heated at 25°C.
into a stainless steel autoclave container, then 1
Heated at 30°C for 6 hours. As a result, a gel-like substance was formed in the container and showed no fluidity.

Example 10 100 g of alkaline aqueous silica sol with SiO2 concentration of 21% by weight obtained in Example 1 and S obtained in Comparative Example 1
It was mixed with 100 g of alkaline aqueous silica sol having an iO□ concentration of 219% by weight, and the resulting mixture was left in a sealed lower chamber, but it remained stable for more than 6 months.

Example 11 Commercially available JISB No. Natotsu sodium water glass 02/Na
Pure water was added to the mixture (2O molar ratio: 322, SiO□ content: 285% by weight) to obtain a sodium silicate aqueous solution having an SiO□ concentration of 33% by weight. Separately prepared product name: Amberlight 1
By passing the above sodium silicate aqueous solution through a column packed with a 20B cation exchange resin, the SiO□ concentration was 3.2.
A colloidal aqueous solution of activated silicic acid with a conductivity of 667 μS/cm and a pH of 2.9] was obtained. This liquid contains Aj220
A total of 67 ppm of 3 and Fe2O3 remained. 2000 g of the above colloidal aqueous solution of activated silicic acid was put into a glass container, and then 1.1 g of a 10% by weight aqueous solution of sulfur-IJium hydroxide was added at room temperature with stirring, and stirring was continued for 10 minutes. The colloidal aqueous solution of activated silicic acid is []H4,15
Met.

Next, 12.1 g of a 10% by weight aqueous calcium nitrate solution was added at room temperature with stirring, and 10 minutes later, 13.1 g of a 10% by weight aqueous sodium hydroxide solution was added at room temperature while stirring. The obtained mixed liquid had SiO23.18% by weight and pH
8,08, SiO□/Na2O molar ratio 60, Ca
O206 ppm. The content of the above mixture is 25! Pour into a stainless steel autoclave container and heat at 130℃ for 6 hours.
Heat treatment was performed for a period of time. Electron microscopic observation revealed that the colloidal silica particles in the obtained silica sol had an elongated shape. The thickness was approximately 10 mμ, and the length was 60 to 200 neL. Further, the particle diameter of colloidal silica determined by dynamic light scattering method was 74.9 mμ.

Further, the particle diameter of this colloidal silica calculated by the BET method was 126 mμ. This sol is 5iO73,
The content was 18% by weight, the SiO2/Na2O titration molar ratio was 93, the pH was 9.90, and no gel was observed. Next, the elongated silica sol thin liquid was concentrated at room temperature using an ultrafiltration device to obtain a concentrated silica sol having an SiO2 concentration of 205% by weight. The obtained sol has a specific gravity of 1
132, pH 9.59, viscosity 46.5 cp, SiO□
/Na2O titration molar ratio 107, CaO013% by weight, CCl258pp, SO439ppm,
Contains 3489pp of NNO, conductive wind is 2610μS/c
It was m. No change in the shape of the silica sol was observed even after concentration. This concentrated silica sol is sealed under 6
When stored at 0°C, it was stable even after one month. When this sol was applied onto a glass plate and dried, a better coating was formed than when a conventional sol was used.

Example 12 The same colloidal aqueous solution of activated silicic acid used in Example 11 (32% by weight of SiO□, pH 2.91, conductive air 6
67μS/cm) 2000 g was put into a glass container, and then a 10% by weight aqueous solution of 1-1 to 1-lium hydroxide was added.
2 g was added at room temperature under stirring and stirring was continued for 10 minutes.

The colloidal aqueous solution of activated silicic acid had a pH of 4.30.

Next, 11.7 g of 10% by weight calcium nitrate aqueous solution
was added at room temperature while stirring, and after 1 hour, 13.0 g of a 10% by weight aqueous sodium hydroxide solution was added at room temperature while stirring. The obtained mixed solution contained 3.18% by weight of SiO□, pl
(8°14, Sj, 02/Na2O molar ratio 60
, C: ao 200 ppm. Pour the above mixed solution into a stainless steel autoclave container with an internal capacity of 25ρ,
Heat treatment was performed at 170°C for 1 hour. Electron microscopic observation revealed that the colloidal silica particles in the obtained silica sol had an elongated shape. Thickness is approximately] 2m
μ, the length was 60-300 mμ. In addition, the particle size of colloidal silica determined by dynamic light scattering method is 117 +
It was +Bv. Further, the particle diameter of this colloidal silica calculated by the BET method was 14 mμ. This sol contains 3.18% by weight of SiO2 and 5lo2/Na2
o Titration method molar ratio was 103 and pH was 10.31, and no gel was observed. Next, the elongated silica sol thin liquid is concentrated at room temperature using an ultrafiltration device.
A concentrated silica sol containing 10.0% by weight of SiO□ was obtained. The obtained sol has a specific gravity of 1.061, a pH of 10.06, and a viscosity of 2.
5cp, SiO□/Na2O titration molar ratio 1.09
, CaOO, 07% by weight, (J230ppm
It contained 419 ppm of SSO, 260 ppm of NO, and the conductive wind was 1420 μS/cm. No change in the shape of the silica sol was observed even after concentration.

When this concentrated silica sol was stored at 60°C under closed conditions,
It remained stable even after one month. When this sol was applied onto a glass plate and dried, a better coating was formed than when a conventional sol was used.

Example 13 Pure water was added to the same colloidal aqueous solution of activated silicic acid (SiO□3°2% by weight, pH 2.91, electrical conductivity 667 μS/cm) used in Example 11, and the SiO□ depth was 1.
An activated silicic acid thin solution having a concentration of 6% by weight, a pH of 2.90, and an electrical conductivity of 670 μS/cm was prepared. 2000 g of this activated silicic acid thin liquid
was put into a glass container, and then 1.0 g of a 10% by weight aqueous sodium hydroxide solution was added at room temperature with stirring.
Stirring was continued for a minute. The colloidal aqueous solution of activated silicic acid is I)
It was H4, IO. Then, 8.8 g of a 10% by weight aqueous calcium nitrate solution was added at room temperature with stirring, and after 10 minutes, an additional 7.89 g of a 10% by weight aqueous sodium hydroxide solution was added at room temperature while stirring. The obtained mixed liquid is Si0□15
9% by weight, pH 7,84, SiO□/Na2O
The molar ratio is 60, and CaO is 150 ppm. The above mixed solution was charged into a stainless steel autoclave container with an internal capacity of 25°C, and heat-treated at 130°C for 6 hours. Electron microscopic observation revealed that the colloidal silica particles in the obtained silica sol had an elongated shape. The thickness was approximately 10 mμ, and the length was 60 to 250 mμ. In addition, the particle size of colloidal silica determined by dynamic light scattering method is 8
It was 98 mμ. Further, the particle diameter of this colloidal silica calculated by the BET method was 128 mμ. This sol has 5xO21,59% by weight, SiO2/Na
The 2O titration molar ratio was 95 and the pH was 9.47, and no gel was observed.

Next, the elongated silica sol thin liquid was concentrated at room temperature using an ultrafiltration device to obtain a concentrated silica sol containing 10.1% by weight of SiO2. The obtained sol has a specific gravity of 1061,
pH 9.16, viscosity 32cp, 5in2/Na2O titration molar ratio 110, CaOO, 08% by weight, is 2
7ppm, NO3290ppm, SO412ppm
The conductivity was 1200 μS/cm. No change in the shape of the silica sol was observed even after concentration. When this concentrated silica sol was stored at 60'C under closed conditions, it was stable even after one month. When this sol was applied onto a glass plate and dried, a better coating was formed than when a conventional sol was used.

Comparative Example 6 The same colloidal aqueous solution of activated silicic acid as described in Example 11 (SiO2 3.2% by weight, pH 2.91, conductivity 66)
A thin active silicic acid solution having a SiO2 concentration of 20% by weight, a pH of 2.90, and an electrical conductivity of 820 g S/arIl was prepared by adding pure water to the solution (7 μS/cm). This activated silicic acid thin liquid 2000
g was put into a glass container, then 1.0 g of a 10% by weight aqueous sodium hydroxide solution was added at room temperature with stirring.
Stirring was continued for 0 minutes. pH of colloidal aqueous solution of activated silicic acid
There were 432. Next, 30 g of a 10% by weight aqueous calcium nitrate solution was added at room temperature with stirring, and after 10 minutes, an additional 1 g of calcium nitrate aqueous solution was added with stirring.
789 g of 0% by weight aqueous sodium hydroxide solution was added at room temperature with stirring. The resulting mixture showed SiO2 1.98% by weight, p+(7,42), SiO2/Na2O molar ratio 60, (:ao 500 ppm).

The above mixed solution was charged into a stainless steel autoclave container with an internal capacity of 25 f2, and heat-treated at 130° C. for 6 hours. As a result, a gel-like substance was formed in the container and showed no fluidity.6 Example 14 Commercially available alkaline aqueous sol (particle size 5 millimicrons by 5ears method, SiO2 concentration 20% by weight, specific gravity 11)
29, pH 9.4, viscosity 4 cp) with a hydrogen-type cation exchange resin, pure water was added to the acidic silica sol, and SiO□ concentration was 3.2% by weight, pH 3.2.
Acidic silica sol No. 7 was prepared. This acidic silica sol 2
000 g was put into a glass container having an inner capacity of 3° C., and then 129 g of a 10% by weight aqueous calcium nitrate solution was added with stirring, and the mixture was stirred at room temperature for 10 minutes. Further 10% by weight
142 g of an aqueous sodium hydroxide solution was added at room temperature with stirring, and stirring was continued for 10 minutes. The obtained mixed liquid is Si
0□316% by weight, pH 9.3, SiO2/Na
The 2O molar ratio is 60, and the Ca02 is 15 ppm. Next, the above-mentioned mixed solution was charged into a stainless steel autoclave container having an internal capacity of 2.5°C, and heat-treated at 130°C for 6 hours.

Electron microscopic observation revealed that the colloidal silica particles in the obtained silica sol had an elongated shape. The thickness was about 10 mμ, and the length was 50 to 300 mμ.

In addition, the particle size of colloidal silica determined by dynamic light scattering method is
It was 55 mμ. Further, the particle diameter of this colloidal silica calculated by the BET method was 123 mμ. Figure 4 of the accompanying drawings shows two types of colloidal silica particles in this sol.
A photograph taken with an electron microscope at a magnification of 00,000 times is shown. This sol contains 3.16% by weight of SiO2, Sif□/Na2O
The titration molar ratio was 78 and the pH was 9.6, and no gel was observed. Next, the elongated silica sol thin liquid was concentrated at room temperature using an ultrafiltration device to form SiO□
A concentrated silica sol with a concentration of 16% by weight was obtained. The obtained sol had a specific gravity of 1100, p)+9.54, and a viscosity of 72 cp.
SiO□/Na2O titration molar ratio 90.7, CaO0
11% by weight, 112 2.8ppm, SO434
ppm, contains 273pp of NNO, and has an electrical conductivity of 20
It was 10u 87cm. No change in the shape of the silica sol was observed even after concentration. When this concentrated silica sol was stored at 60° C. under closed conditions, it was stable even after one month. When this sol was applied onto a glass plate and dried, a better coating was formed than when a conventional sol was used.

Example 15 Commercially available acidic aqueous sol (B
By adding pure water to the particle size of 12 millimicrons, 5iO320% by weight, specific gravity 1129, pH 2.9, viscosity 2 cp) obtained by ET method, SiO□ concentration 3.2% by weight, pH 3.65
A thin acidic silica sol solution was prepared. 2000 g of this acidic silica sol thin liquid was put into a glass container with an internal capacity of 3ρ, and then 11.7 g of a 10% by weight calcium nitrate aqueous solution was added.
was added under stirring, and the mixture was stirred at room temperature for 10 minutes. 1 more
142 g of 0% by weight aqueous sodium hydroxide solution was added at room temperature with stirring, and stirring was continued for 10 minutes. The obtained mixed liquid showed Si0□316% by weight and pH 10.47,
The SiO3/Na2O molar ratio is 60 and Ca0200 ppm. Next, the above mixed solution was charged into a stainless steel autoclave container with an internal capacity of 25 f2, and heat-treated at 130° C. for 6 hours.

The obtained silica sol was found to have colloidal silica particles having an elongated shape by electron microscopic observation. Thickness is 15mmμ, length is 50~30mm
It was 0 mμ. Further, the particle diameter of the colloidal silica determined by dynamic light scattering method was 146 mμ.

Further, the particle diameter of this colloidal silica calculated by the BET method was 147 mμ. This sol is SiO□3.1
The content was 6% by weight, the SiO2/Na2O titration molar ratio was 70, the pH was 10.18, and no gel was observed. Next, the elongated silica sol thin liquid was concentrated at room temperature using an ultrafiltration device to obtain an SiO2 concentration of 10.
A 2% by weight concentrated silica sol was obtained. The obtained sol had a specific gravity of 1063, a pH of 9.98, a viscosity of 42 cp, and a SiO□
/ Na2O titration method molar ratio 89, Ca00.07% by weight
, Cj23ppm, SO434ppm, NN
O3273pp and conductivity was 1900μS/cm. No change in the shape of the silica sol was observed even after concentration. When this concentrated silica sol was stored at 60° C. under closed conditions, it was stable even after one month.

When this sol was applied onto a glass plate and dried, a better coating was formed than when a conventional sol was used.

Example 16 Commercially available alkaline aqueous sol made of spherical colloidal silica (particle size 8 mm by BET method, SiO23
0% by weight, pH 9.9, specific gravity 1.21, viscosity 5 cp)
Pure water was added to the acidic aqueous silica sol obtained by treating it with a hydrogen-type cation exchange resin, and the SiO2 concentration was 3.
．． A thin acidic aqueous silica sol solution containing 6% by weight and pH 3.52 was prepared. 2000 g of this acidic silica sol thin liquid was put into a glass container with a content of 3°C, and then 9.0 g of a 10% by weight aqueous solution of magnesium chloride 'a was added under stirring.
The mixture was stirred at room temperature for 10 minutes. Furthermore, 137 g of a 10% by weight aqueous sodium hydroxide solution was added at room temperature with stirring, and 10% by weight was added at room temperature.
Stirring was continued for a minute. The obtained mixed liquid was 5i (h3.5
7% by weight, pH 9,83, SiO2/Na2O
The molar ratio is 70°Mg0190ppm. Next, the above-mentioned mixed solution was charged into a stainless steel autoclave container having an internal capacity of 3°C, and heat-treated at 140°C for 10 hours. Electron microscopic observation revealed that the colloidal silica particles in the obtained silica sol had an elongated shape. The thickness was about 11 mμ, and the length was 40 to 250 mμ. In addition, the particle size of colloidal silica determined by dynamic light scattering method is 88
It was mμ. Further, the particle diameter of this colloidal silica calculated by the BET method was 129 mμ. This sol contains 3.57% by weight of SiO□, and SiO2/Naz
The molar ratio by O titration method was 81, the pH was 9.83, and no gel was observed. Next, the elongated silica sol thin liquid was concentrated at room temperature using an ultrafiltration device to obtain Si.
A concentrated silica sol with an O□ concentration of 15.6% by weight was obtained.

The obtained sol has a specific gravity of 1098, a pH of 9.70, and a viscosity of 8.
3cp, SiO2/Na2O titration molar ratio 103,
MgO823ppm, (4171ppm, SO42
Contains 2ppm, NO34ppm, and has an electrical conductivity of 209
It was 5μS/cm. No change in the shape of the silica sol was observed even after concentration. When this concentrated silica sol was stored at 60° C. under closed conditions, it was stable even after one month.

When this sol was applied onto a glass plate and dried, a better coating was formed than when a conventional sol was used.

Example 17 Pure water was added to the acidic aqueous silica sol obtained by treating the same commercially available alkaline aqueous sol used in Example 14 with a hydrogen-type cation exchange resin to form SiO2.
A thin acidic silica sol solution having a concentration of 32% by weight and a pH of 3.27 was prepared. This acidic silica sol thin >=2000 g was put into a glass container with an inner capacity of 3° C., and then 4.0 g of a 10% by weight calcium chloride aqueous solution was added with stirring, and stirring was continued for 10 minutes at room temperature. Furthermore, monoethanolamine 24
4 g was added at room temperature under stirring and stirring was continued for 10 minutes.

The obtained mixed solution contained 3.19% by weight of SiO2, pH 9,
35, SiO□/monoethanolamine molar ratio 2
7. Ca01100pp. Next, the above mixed solution was charged into a stainless steel autoclave container with an internal capacity of 3 f2,
This was heat-treated at 135° C. for 10 hours. Electron microscopic observation revealed that the colloidal silica particles in the obtained silica sol had an elongated shape. Thickness is 10
~15 mu, and the length was 50-200 mμ.

In addition, the particle size of colloidal silica determined by dynamic light scattering method is
It was 54.0 +nμ. Further, the particle diameter of this colloidal silica calculated by the BET method was 10.3 mμ. This sol contains 3.19% by weight of SiO□, and S
iO2/monoethanolamine titration molar ratio 36 and p
H9.45, and no gel was observed. Next, the elongated silica sol thin liquid was concentrated at room temperature using an ultrafiltration device to obtain a concentrated silica sol having an SiO2 concentration of 15.2% by weight. The obtained sol had a specific gravity of 1.098, a pH of 9.21, a viscosity of E3 cp,
SiO2/monoethanolamine titration molar ratio 47,
C, a0470ppm, Cj23ppm, SO
It contained 435 ppm of NO3 and 290 ppm of NO3, and the electrical conductivity was 1300 μS/cm. No change in the shape of the silica sol was observed even after concentration. When this concentrated silica sol was stored at 60° C. under closed conditions, it was stable even after one month. When this sol was applied onto a glass plate and dried, a better coating was formed than when a conventional sol was used.

Example 18 Pure water was added to the same commercially available acidic aqueous silica sol used in Example 15 to give an SiO□ concentration of 10% by weight and a pH of
A 3.1 acidic silica sol dilution was prepared. 2000 g of this acidic silica sol diluted solution was put into a glass container with an internal capacity of 3J2, and then 10% by weight of calcium nitrate 23
4 g was added under stirring and stirring was continued for 10 minutes at room temperature. Further, 262 g of a 10% by weight aqueous sodium hydroxide solution was added at room temperature with stirring, and stirring was continued for 10 minutes. The obtained mixed liquid showed SiO29.76% by weight, pH 9.79, SiO□/Na2O molar ratio 100, CaO400
It is ppm. Next, the above-mentioned liquid mixture was charged into a stainless steel autoclave container with an internal capacity of 25 f2, and heat-treated at 200° C. for 6 hours. Electron microscopic observation revealed that the colloidal silica particles in the obtained silica sol had an elongated shape. The thickness is about 20 mμ and the length is 10
It was 0 to 400 mμ. Further, the particle size of colloidal silica determined by dynamic light scattering method was 203 mIL. or,
The particle diameter of this colloidal silica calculated by the BET method was 26.4 mμ. This sol is 5iO79,7
Contains 6% by weight, specific gravity 1,061, pH 10.22,
Viscosity 12cp, Sin□/Na2O titration molar ratio 1
17, CaO400ppm, Cl23ppm, S
It contained 47 ppm of O and 3,880 ppm of NO, the conductivity was 2170 μS/cm, and no gel was observed. When this concentrated silica sol was stored at 60° C. under closed conditions, it was stable even after one month. When this sol was applied onto a glass plate and dried, a better coating was formed than when a conventional sol was used.

Comparative Example 7 Water was added to a commercially available acidic aqueous silica sol made of spherical colloidal silica (average particle size 40 millimicrons, 5iO6 20% by weight, specific gravity 1.120, pH 3.0, viscosity 2 cp) to obtain an SiO2 concentration of 3.2. A thin acidic silica sol solution having a pH of 31% by weight was prepared. This acidic silica sol thin liquid 2
000 g was put into a glass container with an internal capacity of 3j2, and then 10.5 g of a 10% by weight aqueous calcium nitrate solution was added with stirring, and the mixture was stirred at room temperature for 10 minutes. Furthermore, 122 g of a 10% by weight aqueous sodium hydroxide solution was added at room temperature with stirring, and stirring was continued for 10 minutes. The obtained mixed liquid is S
It shows 3.16% by weight of iO2, pH 9.3, and SiO2/
The Na2O molar ratio is 70, and the Ca0 is 180 ppm. Next, the above-mentioned mixed solution was charged into a stainless steel autoclave container having an internal capacity of 25°C, and heat-treated at 130°C for 6 hours. As a result of electron microscopic observation of the obtained silica sol, it was found that the shape of the colloidal silica particles was a shape in which spherical particles were connected, and did not have elongation of uniform thickness.

Comparative Example 8 The same commercially available acidic aqueous silica sol used in Example 14 was concentrated using an ultrafiltration method (BET
Particle size 12 millimicrons by method, 30% by weight of 5iO2
, specific gravity 1.1208, pH 2.9, viscosity 2.5 cp)
Pour 2000 g into a glass container with an internal capacity of 3 f2,
Next, 879 g of a 10% by weight aqueous calcium nitrate solution was added with stirring, and the mixture was stirred for 10 minutes at room temperature. Further 10% by weight
80 g of aqueous sodium hydroxide solution was added at room temperature with stirring, and stirring was continued for 10 minutes. The resulting mixture is 5x02
27.7% by weight, p++9.85, SiO2/
The Na2O molar ratio is 100, and the CaO is 1500 ppm.

Next, the above-mentioned mixed solution was charged into a stainless steel autoclave container having an internal capacity of 25e, and heat-treated at 130° C. for 6 hours. As a result, a gel-like substance was formed in the container and did not exhibit fluidity.

(Effects of the Invention) The sol of the present invention provides improvements in various uses compared to conventional silica sols. The ingredients added to the conventional silica sol to make the composition can also be added to the silica sol of the present invention, and the resulting new composition is
It has higher thickening and gelling properties than conventional compositions. Examples of the components to be mixed include the above-mentioned (conventionally known spherical silica sol, non-spherical silica sol produced by peptization method, alkali metal silicate, hydrolyzed solution of alkyl silicate, alumina sol, other metal oxide sol, Examples include water-soluble resins, resin emulsions, thickeners, antifoaming agents, surfactants, refractory powders, metal powders, bentonites, pigments, and coupling agents.

By blending the silica sol of the present invention with various conventionally used paint components, inorganic paints, heat-resistant paints, anticorrosion paints, inorganic-organic composite paints, etc. can be prepared. A dried coating film formed from a paint containing the silica sol of the present invention has few pinholes and almost no cracks. This coating film also has smoothness, is soft enough to easily absorb impact force, and has good adhesion to the substrate, water retention, and antistatic properties. A fired coating film formed from an inorganic paint containing the silica sol of the present invention exhibits good heat resistance.

By blending various adhesive components with the silica sol of the present invention, inorganic adhesives, heat-resistant adhesives, inorganic-organic composite adhesives, etc. can be prepared.

These paints, adhesives, etc. containing the silica sol of the present invention can be applied to various base materials such as glass, ceramics, metals,
It can be applied to surfaces such as plastics, wood, textiles, and paper.

The silica sol of the present invention can be impregnated into felt materials such as ordinary glass fibers, ceramic fibers, and other inorganic fibers. Moreover, these short fibers and the silica sol of the present invention can also be mixed. When the felt material impregnated with the silica sol of the present invention is dried, a felt material with high strength can be obtained. Further, when a mixture of the short fibers and the silica sol of the present invention is formed into a sheet, mat, or other shape and then dried, a sheet, mat, molded article, etc. with high strength can also be obtained. On the surface of these felt-like materials, sheets, mats, molded products, etc.,
Powdering on the surface, which is seen when conventional silica sol is used in the same way, does not appear. Therefore, it has been shown that the colloidal silica particles of the silica sol of the present invention, which are commonly used as a binder for these inorganic fibers, hardly migrate from the inside to the surface of these inorganic fiber molded bodies during drying. There is. These dried molded products are provided as improved products for heat-resistant insulation materials and other uses.

The silica sol of the present invention can also be used as a surface treatment agent for substrates having a porous structure.

For example, when applied to the surface of a hardened material such as concrete, mortar, cement, plaster, clay, etc., this silica sol impregnates from the surface into the interior, and after drying an improved surface layer is obtained. natural and synthetic fibers, their textile products,
It can also be used as a surface treatment agent for paper, wood, etc.

It is also used as a sealing agent for other castings.

A mold for metal casting can be made from a slurry containing the silica sol and refractory powder of the present invention. Since this slurry has a high gelation rate upon drying, it increases mold production efficiency and reduces the incidence of cracks that occur in the mold during firing.

After the silica sol of the present invention is mixed into an organic resin emulsion, resin solution, etc., the dispersion medium is removed to obtain a resin composition containing silica in the resin. This resin composition is
Since they have desirable properties such as high strength, stain resistance, high surface hardness, and hydrophilicity, improved fibers, films, molded articles, etc. can be obtained from the above mixtures or resin compositions. Preferred resin compositions, fibers, films, molded articles, etc. can also be obtained by dispersing colloidal silica particles of the silica sol of the present invention in a polymerizable monomer and then polymerizing this monomer.

If the silica sol of the present invention is added to a catalyst carrier component, an adsorbent component, a molding refractory component, etc. and then molded, a preferable catalyst carrier, adsorbent, refractory, etc. can be obtained.

The silica sol of the present invention can also be used as a thickener, gelling agent, etc. For example, in applications where acids are used in paste or plastic form, the paste or plastic acid is prepared by adding the silica sol of the present invention to phosphoric acid, oxalic acid, butyric acid, chromic acid, or the like. When the silica sol of the present invention is added to dilute sulfuric acid in a battery electrolyte, it turns into a non-flowing gel, and the electrolyte is prevented from flowing out even if the battery is overturned. A gelling liquid injection agent, that is, a grouting agent composition, which is injected into the soft ground in order to strengthen the soft ground, is also an improved grouting agent by adding a gelling agent such as a salt to the silica sol of the present invention. It strengthens the ground and improves water resistance, etc.

The silica sol of the present invention exhibits high stability and has the property of irreversibly changing into a gel upon removal of the medium. When the sol gels or after curing, it exhibits unique properties derived from the sol. It will be easily understood that it is useful for various uses in addition to the above-mentioned uses.

[Brief explanation of the drawing]

FIG. 1 is a transmission electron micrograph showing the particle structure of colloidal silica in the concentrated sol obtained in Example 1 with a magnification of 200,000 times. FIG. 2 is a transmission electron micrograph showing the particle structure of colloidal silica in the concentrated sol obtained in Comparative Example 1, and FIG. This is a 200,000x transmission electron micrograph showing the particle structure of silica. FIG. 4 is an electron micrograph at a magnification of 200,000 times showing the particle structure of colloidal silica in the sol of the present invention obtained in Example 14 before concentration.

Claims (1)

[Claims] (1) Ratio D of the particle diameter measured by the dynamic light scattering method (D_1 mμ) and the particle diameter measured by the nitrogen gas adsorption method (D_2 mμ)
_1/D_2 is 5 or more, and this D_1 is 40 to 5
Amorphous colloidal silica particles of elongated shape having a uniform thickness in the range of 5 to 40 millimicrons and elongation in only one plane as determined by electron microscopy are dispersed in a liquid medium. SiO_2 concentration 0.5
~30% by weight stable silica sol. (2) Consisting of the following steps (a), (b) and (c),
Ratio D_1/ of particle diameter measured by dynamic light scattering method (D_1 mμ) and particle diameter measured by nitrogen gas adsorption method (D_2 mμ)
D_2 is 5 or more, this D_1 is 40 to 300 millimicrons, and 5 to 2 by electron microscopy observation.
A method for producing a stable alkaline aqueous silica sol with a SiO_2 concentration of 1 to 6% by weight, consisting of elongated amorphous colloidal silica particles with a uniform thickness within the range of 0 mm and elongation in one plane only; ( a) Contains 1 to 6% by weight as SiO_2, and
An aqueous solution containing a water-soluble calcium salt, a magnesium salt, or a mixture thereof is added to a colloidal aqueous solution of activated silicic acid having a pH of 2 to 4, and an aqueous solution containing CaO, MgO
or (b) adding and mixing both in an amount such that the weight ratio is 1,500 to 8,500 ppm; and (a) adding an alkali metal hydroxide, a water-soluble organic base, or a water-soluble silicate thereof to the aqueous solution obtained in step (a). /M_2O (However, SiO_2 represents the silica content derived from the above-mentioned activated silicic acid and the silica content of the above-mentioned silicate, and M represents the above-mentioned alkali metal atom or organic base molecule.) The molar ratio is 20 to 200. Step (c) of adding and mixing the mixture obtained in step (b) to 60 to 15
A step of heating at 0°C for 0.5 to 40 hours. (3) The colloidal aqueous solution of activated silicic acid used in step (a) has a SiO_2/Na_2O molar ratio of 1 to 4.5 and a Si
It is obtained by contacting an aqueous solution of sodium water glass having an O_2 concentration of 1 to 6% by weight with a hydrogen type cation exchange resin, and has a SiO_2 concentration of 1 to 6% by weight and a pH of 2 to 4. 3. The method for producing a stable alkaline aqueous silica sol according to claim 2, wherein the sol does not contain colloidal silica having a particle size of 3 millimicrons or more. (4) Consisting of the following steps (a), (b) and (c),
Ratio D_1/ of particle diameter measured by dynamic light scattering method (D_1 mμ) and particle diameter measured by nitrogen gas adsorption method (D_2 mμ)
D_2 is 5 or more, this D_1 is 40 to 300 millimicrons, and 5 to 2 by electron microscopy observation.
A method for producing a stable alkaline aqueous silica sol with a SiO_2 concentration of 1 to 6% by weight, consisting of elongated amorphous colloidal silica particles with a uniform thickness within the range of 0 mm and elongation in one plane only; ( a) Contains 1 to 6% by weight as SiO_2, and
An aqueous solution containing a water-soluble calcium salt, a magnesium salt, or a mixture thereof is added to a colloidal aqueous solution of activated silicic acid having a pH of more than 4 and less than or equal to 5.
Step (b) of adding and mixing an amount of CaO, MgO, or both in a weight ratio of 1,500 to 8,500 ppm to _2. Adding an alkali metal hydroxide, a water-soluble organic base, or the like to the aqueous solution obtained in step (a) water-soluble silicate of SiO_2/M_2O (where, SiO_2 represents the silica content derived from the above-mentioned active silicic acid and the silica content of the above-mentioned silicate, and M represents the above-mentioned alkali metal atom or organic base molecule) mole. Step (c) of adding and mixing the mixture so that the ratio is 20 to 200; and (b) the mixture obtained in step 60 to 25
A step of heating at 0°C for 0.5 to 40 hours. (5) The colloidal aqueous solution of activated silicic acid used in step (a) has a SiO_2/Na_20O molar ratio of 1 to 4.5 and S
It is obtained by contacting an aqueous solution of sodium water glass with an iO_2 concentration of 1 to 6% by weight with a hydrogen type cation exchange resin, and has a SiO_2 concentration of 1 to 6% by weight and a pH of more than 4 and less than or equal to 5. 5. The method for producing a stable alkaline aqueous silica sol according to claim 4, which contains no colloidal silica having a particle size of 3 millimicrons or more. (6) From the silica sol obtained by the step (c) according to any one of claims 2 to 5, anions and water contained in the sol are removed to an anion concentration of 0.1% by weight or less. SiO_2 concentration 2-3
The ratio D_1/D_2 of the particle diameter measured by dynamic light scattering method (D_1 mμ) and the particle diameter measured by nitrogen gas adsorption method (D_2 mμ) is 5 or more, characterized in that the particle size is removed until it becomes 0% by weight,
This D_1 is 40 to 300 millimicrons and consists of elongated amorphous colloidal silica particles with a uniform thickness in the range of 5 to 20 millimicrons and elongation only in one plane as observed by electron microscopy. SiO_2 concentration 2
A method for producing a stable alkaline aqueous silica sol of ~30% by weight. (7) Ratio of the particle diameter measured by the dynamic light scattering method (D_1 mμ) and the particle diameter measured by the nitrogen gas adsorption method (D_2 mμ), which consists of the following steps (a'), (b') and (c'). D_1/D_2 is 5 or more, D_1 is 40 to 500 millimicrons, and an elongated elongate having a uniform thickness in the range of 5 to 40 millimicrons and elongation only in one plane as observed by electron microscopy. Method for producing a stable alkaline aqueous silica sol with a SiO_2 concentration of 0.5 to 25% by weight, consisting of amorphous colloidal silica particles having a shape; An aqueous solution containing a water-soluble calcium salt, a magnesium salt, or a mixture thereof is added to an acidic aqueous silica sol containing ~25% by weight and having a pH of 1 to 5. 0.15 to 1 as MgO or both.
(b') To the liquid obtained in (a') step, add an alkali metal hydroxide, a water-soluble organic base, or a water-soluble silicate thereof to the solution of SiO_2/M_2O( However, SiO_2 represents the silica content derived from the acidic sol and the silica content of the silicate, and M represents the alkali metal atom or organic base molecule.) Added so that the molar ratio is 20 to 300. (c') By heating the mixture obtained in step (b') at 60 to 300°C for 0.5 to 40 hours, the mixture used in step (a') is added to the mixture. A step of producing the elongated colloidal silica particles having a thickness equal to or larger than the particle size of the colloidal silica. (8) From the silica sol obtained by the step (c') according to claim 7, anions and water contained in the silica sol are removed with an anion concentration of 0.1% by weight or less and a SiO_2 concentration of 1 to 40%. The ratio D_1/D_2 of the particle diameter measured by the dynamic light scattering method (D_1 mμ) and the particle diameter measured by the nitrogen gas adsorption method (D_2 mμ) is 5 or more, which is characterized by removing up to % by weight. D_1 is 40-500 millimicrons, and SiO_2 consists of elongated shaped amorphous colloidal silica particles with uniform thickness in the range of 5-40 millimicrons and elongation only in one plane according to electron microscopy. A method for producing a stable alkaline aqueous silica sol having a concentration of 1 to 40% by weight.