JP3463328B2 - Method for producing acidic silica sol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to colloidal silica particles.
With a diameter of 4 to 30 millimicrons and a pH of 2 to 5
The present invention relates to a method for producing a constant acidic silica sol. Acidic silica sol
Does not contain bases such as alkali metals.
Applications where the absence of bases such as metals is desired, such as metals
Surface treatment agents, surface treatment agents such as glass fiber,
It is used as a decoating agent. [0002] 2. Description of the Related Art Stability of industrial products used for various purposes
Water-soluble silica sol is a water-soluble alkali metal silicate,
Manufactured from water glass, an industrial product that can be obtained at low cost
I have. The stable aqueous silica sol of this industrial product is alkaline
The inclusion of a base such as a metal may make some applications, e.g.
Hermic acid mixed with humic acid-based metal surface treatment agent and organic solvent
For applications such as coating agents and ceramic fiber raw materials
However, alkaline silica sols are inconvenient. these
Stable acidic aqueous silica sol (hereinafter referred to as acidic silica
Sol) is required. [0003] Alkaline silica sol is converted to cation exchange resin
Acid silica sol
Although it is known that it can be obtained,
Since the zeta potential of mosquito is small, the electricity of colloid
Target repulsion is reduced, especially the colloidal silica particle size
As the size decreases, the acidic silica sol becomes unstable. Also,
Colloidal silica is also a cation exchanger,
Colloidal silica in silica sol produced as raw material
Cation exchange due to strong adsorption of sodium ions
It cannot be sufficiently removed by resin treatment,
Silica sol is sodium
Release of ON raises the pH of the sol and destabilizes it
Has disadvantages. A method for producing a stable acidic silica sol is as follows.
The following method has been proposed. Tokiko 30-3527
In this publication, an alkaline silica sol containing an electrolyte is
Treated with ion exchanger, then treated with anion exchanger
And stable acidic silica sol containing substantially no electrolyte
Is disclosed. U.S. Pat. No. 2,892,797
In the specification, aqueous alumina sol is added to aqueous sodium sol
Add water-soluble metal salt aqueous solution of amphoteric metal such as solution
Thus, a method for producing a stable silica sol having a pH of 5 to 12
It has been disclosed. [0005] US Pat. No. 3,342,747 discloses A
After treating the lukali silica sol with a cation exchange resin,
After adding a small amount of acid and aging, treat with cation exchange resin again
Of acidic silica sol stabilized by acid
A law is disclosed. JP-A-63-123807
Alkaline silica gel containing aluminum compound
(I) an acidic silicic acid solution and an aqueous aluminum compound solution,
Simultaneously or alternately, SiO_TwoContaining alkaline aqueous solution or
A method of adding to an aqueous solution of a alkali metal hydroxide, (ii)
The acidic silicic acid solution mixed with the ruminium compound is_TwoIncluding
Add to alkaline aqueous solution or alkali metal hydroxide aqueous solution
Prepared by the method of (i) or (ii).
Alkaline silica sol containing luminium compound as cation
Consisting of treating with exchange resin and dealkalizing, stable
A method for producing a novel acidic silica sol is disclosed. [0006] Problems to be Solved by the Invention
No. 27 and US Pat. No. 3,342,747.
In the method, the zeta potene of colloidal silica in acidic
The char is not big enough to get enough stability
No. Japanese Patent Publication No. 30-3527 discloses this acidic silica sol.
Is disclosed to be unstable upon heating. Ma
In addition, the acidic silicone disclosed in U.S. Pat. No. 3,342,747 is disclosed.
Ricasol contains a small amount of acid, so metal surface treatment etc.
This is inconvenient for the use of. [0007] R. K. RK Iler
The Chemistry of Silica (The Chemi
in the book of St. Silica)
Reaction between acid ions and silanol groups on the surface of colloidal silica
Aluminosilicate sites generated by the reaction
Giving negative charge to colloidal silica in kasol
Says. In other words, aluminosilicate sites are negative
Increase the zeta potential of
Will be standardized. However, US Pat. No. 2,892,797 describes
The silica sol obtained by the method of the present invention is stable at pH 5-12.
However, aggregation or gelation occurs at pH 5 or lower.
It is disclosed that a stable acidic system having a pH of 2 to 5 can be used.
Ricasol has not been obtained. JP-A-63-123807
In the method disclosed in Japanese Patent Application Publication No.
Colloidal silica by containing and growing particles
The aluminum compound is encapsulated in the particles of
Acidic silica stable by trapping existing alkali
It is said that a sol can be obtained. However, in this method,
Acid silica sol is formed by the formation of luminosilicate sites
Stabilizes, but also removes internal parts that are not necessary for stabilization.
Because the luminosilicate sites are being generated,
High aluminum content in idal silica
Nato remaining on the aluminosilicate site
Alkali such as lium also increases. Therefore, the obtained acidic silica sol is heated.
It has the drawback of higher pH and poor stability.
You. The use of acidic silica sol has been expanding in recent years,
An acidic silica with the same level of stability as alkaline silica sol
Providing licasol is a challenge. The present invention
In order to solve such problems and the problems of the above manufacturing method,
To modify the surface of colloidal silica
Depending on the method, the particle diameter of colloidal silica is 4 to 30 mm.
Preparation of stable acidic silica sol with micron and pH 2-5
It is intended to provide a manufacturing method. [0010] Means for Solving the Problems The colloid of the present invention
Lica has a particle size of 4-30 millimicrons and a pH of 2
(A), (b)
And (c) steps. (A) Colloidal silica particle diameter of 4 to 30 mm
And the pH is 2-9.And aluminum
Al content ₂ O ₃ / SiO ₂ 0 to 0.00 in molar ratio
Have a ratio of 08Al in silica sol₂O₃/ SiO
₂Molar ratio exceeds 0.0006 but not more than 0.004
To add an aqueous solution of alkali aluminate
About (B) The silica sol obtained by the step (a) is
Heating at ~ 250 ° C for 0.5-20 hours, (C) converting the silica sol obtained in the above step (b) into a cation
Contact with exchange resin or cation exchange resin and anion exchange resin
The acidic silica sol having a pH of 2 to 5
The step of generating. The colloid used in the step (a) of the present invention
The particle size of silica is 4-30 millimicrons and the pH is
The silica sol having a value of 2 to 9 should be produced by a known method.
Can be done. For example, Bird, U.S. Pat.
No. 244325 and Betitol (Bectol)
d) and Snyder
Sodium silicate as disclosed in JP-A-18
It is manufactured by a method using ion exchange method from aqueous solution
Built. The silica used in the step (a) of the present invention
The pH of the sol is disclosed in JP-B-30-3527.
As shown, the alkaline silica sol is
Acid silica sol obtained by treating with fats and anion exchange resins
It can be controlled by adding alkali.
I can do it. The raw material sodium silicate aqueous solution is made from natural silica sand.
Because it contains aluminum,
Silica sol produced by the above method is generally Al_TwoO
_Three/ SiO_TwoAluminum with a molar ratio of 0.0008 or less
It contains. In the step (a) of the present invention, ethylsilicone is used.
Kate is used as a raw material and hydrolyzed in the presence of alkali
Sol containing no aluminum at all
Can be used. Used in step (a) of the present invention
Silica sol has an aluminum content of Al_TwoO _Three/ S
iO_TwoThe molar ratio is preferably from 0 to 0.0008. Also,
Manufactured from water glass with high luminium content, or
One disclosed in JP-A-63-123807.
The aluminum content produced by the method is Al_TwoO_Three/
SiO_TwoEven silica sol with a molar ratio of 0.0008 or more is used.
Can be used, but Al_TwoO_Three/ SiO_Two0.001 in molar ratio
If it is 5 or more, the effect is small. The silica sol used in the step (a) of the present invention
SiO_TwoThe concentration is not particularly limited, but is 5 to 50% by weight.
Is preferred. Silica sol used in step (a) of the present invention
The particle size of the colloidal silica in the table is a ratio table by the BET method.
In terms of particle size converted from area or specific surface area by Sears method
4 to 30 millimicrons. Sears Act, Analete
Logical Chemistry (ANALYTICAL CHE)
MISTRY) Volume 28 No. 12 (December 1956)
As described on page 1981, sodium hydroxide
Of particle size converted from specific surface area by titration
It is a fixed method. The pH of the silica sol used in the step (a) is
2-9 are preferred. Particularly, pH 4 to 7 is preferable. This p
H4-7 silica sol was produced by a known method.
Commercially available as alkaline silica sol and industrial chemicals
Cation exchange resin or cation
Treated with an ion exchange resin and an anion exchange resin,
After producing the acidic silica sol, alkali metal hydroxide water
Solution, aqueous ammonia, amine, quaternary ammonium hydroxide
Adjust the pH to 4-7 by adding a base such as
Can be manufactured. This sol is manufactured due to instability
It is preferred to use it immediately afterwards. The aluminate used in the step (a)
Sodium aluminate, aluminum
Potassium, quaternary ammonium aluminate, aluminate
An aqueous solution of guanidine acid or the like can be used.
Sodium aluminate aqueous solution commercially available as industrial chemical
Liquids are particularly preferred. Na of sodium aluminate aqueous solution
_TwoO / Al_TwoO_ThreeThe molar ratio is preferably from 1.2 to 2.0. In the step (a), silica having a pH of 2 to 9 is used.
Addition of the aqueous alkali aluminate solution to the sol is carried out while stirring.
~ 80 ° C, preferably 5-60 ° C
You. The stirring is performed by Satake type, Faudler type, Disper type stirring.
It can be performed with a stirrer, homomixer, etc.,
The stirring speed is preferably high. Al aluminate to be added
Potassium solution is Al_TwoO_ThreeUsed at a concentration of 0.5 to 10% by weight
Preferably. Addition time of aqueous alkali aluminate solution
May be long, but usually less than 10 minutes is good. In the step (a), the silica sol
The amount of the aqueous alkali aluminate solution depends on the silica
Sol Al_TwoO_Three/ SiO_TwoExceeds 0.0006 in molar ratio
However, 0.004 or less is preferable. Especially 0.0008
But preferably 0.004 or less. (A) In the process
The resulting silica sol has a pH of 5-11. pH 6 ~
10 is more preferred. In the step (b), the silica sol obtained in the step (a) is used.
And a heating temperature of 80 to 250.
C., particularly preferably 100 to 200.degree. The heating time is 0.
5-20 hours are preferred. (B) SUS for heating in the process
And glass and pressure equipment can be used.
You. Cation exchange resin or cation in step (c)
Contact between the anion exchange resin and the anion exchange resin at 0-60 ° C.
Although it can be used, 5 to 50 ° C. is particularly preferable. Cation exchange
Hydrogen type strongly acidic cation exchange resin is preferred as the resin.
And is easily obtained as a commercial industrial product. Examples and
The trade name is Amberlite IR-120B
You. Hydroxyl type strong basic anions are used as anion exchange resins.
Exchange resin is preferred, and it is easy to enter as a commercial industrial product.
Be handed. An example is the product name Amberlite IRA
-410. In step (c), ion exchange with silica sol is performed.
Contact with the exchange resin is performed in a column filled with the ion exchange resin.
This is preferably done by passing silica sol through
And the speed of passing through the silica sol column is 1 hour
The space velocity per interval is preferably about 1 to 10. (C) Step
Silica sol, cation exchange resin and anion exchange resin
Contact with the cation exchange resin first
And then preferably in contact with an anion exchange resin,
When this silica sol is brought into contact with the cation exchange resin again,
More preferred. In the step (c), obtained in the step (b)
Silicate sol is not diluted and is_TwoPermeate by concentration
However, if diluted and passed through, or
(C) SiO of silica sol obtained by step_TwoConcentration
If it decreases, use an evaporation method or a microporous membrane
Concentration by the method such as_TwoIncrease concentration
I can do it. The acidic silica sol obtained by the step (c)
Has a pH of 2-5. Each of (a), (b) and (c)
The particle size of the silica sol in the process is determined by the ratio according to the BET method.
Converted particle size from surface area or specific surface area by Sears method
Can be obtained as [0022] [Action] To stabilize the acidic silica sol,
Alumino necessary and sufficient for stabilization on idal silica surface
It is necessary to form silicate sites.
In step (a), the aluminosilicate site is
To produce silica sol, add alkaline aluminate water
The solution is added. Sufficient aluminate necessary for stabilization
The aqueous solution of lukali is strictly the surface area of colloidal silica,
That is, it depends on the particle size.
The required amount of the alkali acid aqueous solution increases,
Aluminum content of silica sol (aluminosilicate
Existing as a site)
The lower the aluminum content of the sol, the more the aluminate
Although the required amount of the aqueous solution of lukari increases, the alkali aluminate
The addition of the aqueous solution depends on the aluminum of the silica sol after the addition.
Al content_TwoO_Three/ SiO_Two0.0006 in molar ratio
However, it may be set to 0.004 or less. Special
Over 0.0008, but below 0.004
Is enough. In the step (a), the silica sol is added
Aluminate ion is silanol on the surface of colloidal silica.
Alumino-silicone on the colloidal silica surface
Kate sites are generated, but only in step (a)
The reaction did not occur sufficiently, and the silica sol obtained in step (a)
Even when contacted with a cation exchange resin to obtain an acidic silica sol,
This acidic silica sol does not have sufficient stability. this
Alkali is removed by contact with cation exchange resin
The pH of the silica sol becomes acidic to 2 to 5,
Aluminate ions that have not sufficiently reacted with the
It becomes minium ion and is removed by cation exchange resin.
Aluminosilicate necessary for stabilization
This is presumed to be due to a significant shortage of sites. The silica sol used in the step (a) is Si
O_TwoIt is also possible to use a silica sol having a concentration of less than 5% by weight.
Yes, but production efficiency is low and more than 50% by weight
In this case, the formation of aggregates is likely to occur in the step (a).
Therefore, it is not preferable. (A) Silica sol used in the process
Means that aluminum is Al_TwoO_Three/ SiO_TwoIn the molar ratio of
Silica sol containing 0.0008 or more, especially Al_TwoO
_Three/ SiO_TwoWith a molar ratio of 0.0015 or more
In the case of Cazol, a sufficient amount of Al
The effect is exhibited due to the presence of minosilicate sites
Is not preferred. The roller in the silica sol used in the step (a)
Particle size of idal silica is less than 4mm
The diameter is too small to obtain a stable silica sol.
If it exceeds millimicrons, the aluminum content
Al_TwoO_Three/ SiO_TwoEven if the molar ratio is 0.0008 or less
It has been found that a stable acidic silica sol can be obtained by a known method.
Therefore, the effects of the present invention are hardly exhibited. The pH of the silica sol used in the step (a) is
If it is less than 2, the aqueous alkali aluminate solution is added in the step (a).
Aggregates are easy to form when added, pH exceeds 9
If necessary, add a sufficient amount of aqueous alkali aluminate solution.
And the effect of the present invention is hardly exhibited.
Therefore, it is not preferable. In the step (a), the silica sol
The addition amount of the aqueous alkali aluminate solution is
Al in silica sol_TwoO_Three/ SiO_TwoIn a molar ratio of 0.0
Below 006, the effect of the present invention is small, and 0.00
4 may be added, but no more
This is not preferable because no improvement in the effect is observed. PH of silica sol obtained in step (a)
If less than 5, gelation easily occurs in step (b), and 11
In the above, the colloidal silica particles grow in the step (b).
It is not preferable because it easily becomes stiff. (B) In the process
(A) heating the silica sol obtained in the step;
From the reaction between the silanol group and aluminate ion.
To form strong aluminosilicate sites
Rukoto can. The silica sol obtained in the step (b) is strong
Extremely strong because it has many solid aluminosilicate sites
Stable even when the pH is 5 or less by adding an acid.
It is fixed. The formation of this aluminosilicate site is heated
The higher the temperature, the more effective. If the heating temperature in the step (b) is lower than 80 ° C.
The effect of the present invention is insufficiently expressed, and exceeds 250 ° C.
In this case, the growth of colloidal silica is likely to occur.
Not preferred. The heating time of the step (b) is less than 0.5 hours.
In the case of full, the effect is insufficient, even if it is more than 20 hours
Good, but not preferred because it is not efficient. In the step (c), obtained in the step (b)
Silica sol and cation exchange resin or cation exchange resin
Remove alkali by contacting with anion exchange resin.
With this, an acidic silica sol having a pH of 2 to 5 can be obtained.
You. At this time, in step (b), strong aluminosilicate
Are removed together with the alkali due to the formation of
Aluminum is low, and the resulting acidic silica sol
Contains sufficient aluminosilicate sites necessary for stabilization
Can be done. (B) The higher the heating temperature of the process
Less aluminum is removed in the step (c). In each of the above steps (a), (b) and (c)
All the silica sols obtained from the above were colloidal silica
Is stable without remarkable aggregation. In this silica sol
Particle size of colloidal silica at room temperature was determined by dynamic light scattering
In each process, this particle size
Little change is observed. According to this dynamic light scattering method
The method for measuring the particle size is described in the Journal of Chemical
Zix (Journal of Chemical P
physics) Vol. 57, No. 11, December 1972
It is described on page 4814, for example, commercially available US
Coulter, N_FourEquipment called
With this, the particle diameter can be measured. Acidic silica sol obtained by step (c)
Is 5 to 40% by weight of SiO_TwoWith concentration, colloidal
Rica particle size is specific surface area or sears by BET method
4 to 30 mm in converted particle size from specific surface area
, PH 2-5, aluminum content
Is Al_TwoO_Three/ SiO_Two0.0006 to 0.0 in molar ratio
035. This acidic silica sol has the necessary properties for stabilization.
Has luminosilicate sites, alkali content
PH, viscosity, etc. even at high temperature storage
Change is less likely to occur and is stable at 80 ° C. for one month or more. [0032] 【Example】 Preparation of raw silica sol As a raw material, a commercially available aqueous sodium silicate solution (No. 3 water glass)
  Fuji Chemical Co., Ltd.) was prepared. This water glass is Si
O_Two28.8% by weight, Na_TwoO 9.47% by weight, SiO
_Two/ Na_TwoO molar ratio 3.14, Al_TwoO_Three490pp
m, Al_TwoO_Three/ SiO_TwoThe molar ratio is 0.0010
Was. This water glass is diluted with pure water to form SiO 2 _TwoConcentration 3.
After preparing a 6% by weight aqueous solution of sodium silicate, cation exchange
Alternatively, SiO_TwoConcentration: 3.52% by weight, Al_TwoO_Three4
1.5 ppm, Al_TwoO_Three/ SiO_TwoMolar ratio 0.000
An aqueous solution of active silicic acid having a pH of 2.78 and a pH of 2.78 was obtained. In a 50 liter SUS reaction vessel
10% water in a reactor equipped with a stirrer, heating device, etc.
Charge 217 g of sodium oxide aqueous solution and 5210 g of pure water
After heating to 85 ° C, the active silica is dissolved in water.
Take 6.0 hours while maintaining 39200 g of the liquid at 85 ° C.
After continuous feeding, maintain at reflux for 4.0 hours
Thus, 44627 g of an alkaline silica sol thin solution was obtained.
This silica sol thin solution is SiO_Two3.09% by weight, pH
9.90, Al_TwoO_Three36.4 ppm, colloidal sily
Mosquito particle size (converted from BET specific surface area) 13.7
Millimicrons. Then, this alkaline silica
The sol thin solution is treated with SiO at room temperature using an ultrafiltration device._Twoconcentration
Concentrated to 33.5% by weight,
4120 g were obtained. This silica sol has a specific gravity of 1.23.
0, pH 9.14, viscosity 20.6 c. p. , SiO_Two3
3.5% by weight, Na_TwoO (titration method) 0.23% by weight, N
a_TwoO (flame light method) 0.28% by weight, Al_TwoO_Three395p
pm, Al_TwoO_Three/ SiO_TwoMolar ratio 0.00069,
Conductivity 2570 μs / cm, particle diameter (BET method) 13.7
Millimicron, particle diameter (dynamic light scattering method) 30 millimicron
Was. Particle size measurement by dynamic light scattering method is commercially available
Coulter, USA, N_FourEquipment
Was measured. The alkaline silica sol is subjected to cation exchange.
Anion exchange with resin (Amberlite IR-120B)
Color filled with resin (Amberlite IRA-410)
The resulting solution was passed through a column to obtain an acidic silica sol. This acidic silica
The sol had a specific gravity of 1.127, a pH of 2.53, and a viscosity of 1.6 c.
p. , SiO_Two20.53% by weight, Na_TwoO (flame light method)
250 ppm, Al_TwoO_Three210 ppm, Al_TwoO_Three/
SiO_TwoMolar ratio 0.00058, conductivity 764 μs / c
m, Cl 2 ppm, SO_Four3 ppm, particle size (BET
Method) 13.7 mm, particle diameter (dynamic light scattering method) 3
0 micron. Embodiment 1 Step (a) The above acidic silica sol (SiO_Two20.53
Wt%, Al_TwoO_Three210 ppm, pH 2.53) 40
3.0 g of an aqueous sodium hydroxide solution was added to 00 g while stirring.
And stirred for about 1 hour, acidic silica sol of pH 4.20
I got This acidic silica sol was used immediately after preparation.
Commercially available sodium aluminate aqueous solution (manufactured by Sumitomo Chemical Co., Ltd.)
  NA-150 Al_TwoO_Three21.4% by weight, Na_TwoO
19.5% by weight, Na_TwoO / Al_TwoO_ThreeMolar ratio 1.5
0, Cl 10 ppm or less, SO_Four20 ppm or less) 3
Add 148.3 g of pure water to 0.0 g and add Al_TwoO_Threeconcentration
A 3.6% by weight aqueous solution of sodium aluminate was obtained. The acidic silica sol having pH 4.20 (Si
O_Two20.51% by weight, Al_TwoO_Three210 ppm) 10
Sodium aluminate aqueous solution with stirring at room temperature
(Al_TwoO_Three7.6 g (3.60% by weight) were added.
The mixture was stirred for 5 hours to obtain a silica sol having a pH of 6.51. this
Silica sol has a specific gravity of 1.129, pH 6.51, and a viscosity of 3.
8c. p. , SiO_Two20.36% by weight, Al_TwoO_Three4
80 ppm, Al_TwoO _Three/ SiO_TwoMolar ratio 0.0013
9. Particle size (BET method) 13.7 mm, particle size
(Dynamic light scattering method) It was 32 millimicrons. (B) Step The pH 6.51 silica obtained in the above step (a) is used.
SUS autoclave with 1.5 liter kasol
And heated at 130 ° C. for 4 hours. Thickening by heating
No abnormalities such as conversion to rupturing were observed. Silazozo obtained
Has a pH of 7.06 and a viscosity of 3.3 c. p. , Particle size (BE
T method) 13.7 mm, particle size (dynamic light scattering method)
It was 31 millimicrons. (C) Step The pH 7.06 silica obtained in the above step (b) is obtained.
1000 g of Cazol is converted to a cation exchange resin (Amberlite
IR-120B) packed in a column packed with
The solution was passed at room temperature at a speed of 4 and 1020 g of acidic silica sol was passed through.
Obtained. This acidic silica sol has a specific gravity of 1.126 and a pH of 2.
62, viscosity 1.7 c. p. , SiO_Two20.0% by weight,
Al_TwoO_Three400 ppm, Al_TwoO_Three/ SiO_TwoMolar ratio
0.00118, Na_TwoO290 ppm, conductivity 874
μs / cm, particle diameter (BET method) 13.7 mm
Particle diameter (dynamic light scattering method) 31 mm, Cl
2 ppm, SO_FourIt was 3 ppm. Embodiment 2 (A) Step Acidity of pH 4.20 described in Example 1 above
Silica sol (SiO_Two20.51% by weight)
The sodium aluminate described in Example 1 above at room temperature and with stirring.
Lithium aqueous solution (Al_TwoO_Three3.60% by weight) 15.9 g
Was added and stirred for 0.5 hour.
I got This silica sol has a specific gravity of 1.128 and a pH of 7.
38, viscosity 3.4 c. p. , SiO_Two20.19 weight
%, Al_TwoO _Three769 ppm, Al_TwoO_Three/ SiO_TwoMo
Ratio of 0.00224, particle size (BET method) 13.7 mm
Micron, particle diameter (dynamic light scattering method) at 32 millimicron
there were. Step (b) The pH 7.38 silica obtained in the above step (a)
SUS autoclave with 1.5 liter kasol
And heated at 130 ° C. for 4 hours. Gel thickened by heating
No abnormalities such as transformation were observed. Silica sol obtained
Has a pH of 7.86 and a viscosity of 3.1 c. p. , Particle size (BET
Method) 13.7 mm, particle diameter (dynamic light scattering method) 3
1 millimicron. (C) Step The pH 7.86 silica obtained in the above step (b) is obtained.
1000 g of Cazol is converted to a cation exchange resin (Amberlite
Column packed with IR-120B)
The solution was passed at room temperature at a speed of 4 to obtain 960 g of acidic silica sol.
Was. However, due to the silica concentration, the flow at the beginning and end
The liquid was cut. This acidic silica sol has a specific gravity of 1.12.
7, pH 2.57, viscosity 1.9 c. p. , SiO_Two2
0.19% by weight, Al_TwoO_Three598 ppm, Al_TwoO_Three
/ SiO_TwoMolar ratio 0.00174, Na _TwoO (flame light method)
310 ppm, conductivity 1020 μs / cm, particle diameter (B
ET method) 13.7 mm, particle size (dynamic light scattering)
Method) 31 millimicron, Cl 4ppm, SO_Four3pp
m. Embodiment 3 (A) Step Acidity of pH 4.20 described in Example 1 above
Silica sol (SiO_Two20.51% by weight)
The sodium aluminate described in Example 1 above at room temperature and with stirring.
Lithium aqueous solution (Al_TwoO_Three3.60% by weight)
Add and stir for 0.5 hours, pH 6.00 silica sol
I got This silica sol has a specific gravity of 1.129 and a pH of 6.0.
0, viscosity 4.0 c. p. , SiO_Two20.43% by weight,
Al_TwoO_Three353 ppm, Al_TwoO_Three/ SiO_TwoMolar ratio
0.00101, particle size (BET method) 13.7 mm
Ron, particle size (dynamic light scattering method)
Was. (B) Step The pH 6.00 silica obtained in the above step (a) is obtained.
SUS autoclave with 1.5 liter kasol
And heated at 140 ° C. for 4 hours. Thickening by heating
No abnormalities such as conversion to rupturing were observed. Silazozo obtained
Has a pH of 6.70 and a viscosity of 3.5 c. p. , Particle size (BE
T method) 13.7 mm, particle size (dynamic light scattering method)
32 millimicrons. Step (c) The pH 6.70 slurry obtained in the above step (b)
1000 g of Cazol is converted to a cation exchange resin (Amberlite
IR-120B) packed in a column packed with
The solution was passed at room temperature at a speed of 4 and 1020 g of acidic silica sol was passed through.
Obtained. This acidic silica sol has a specific gravity of 1.126 and a pH of 2.
67, viscosity 1.6c. p. , SiO_Two20.03 weight
%, Al_TwoO_Three306 ppm, Al_TwoO_Three/ SiO_TwoMo
Ratio 0.0090, Na_TwoO (flame light method) 270pp
m, conductivity 795 μs / cm, particle diameter (BET method) 1
3.7 mm, particle diameter (dynamic light scattering method) 32 mm
Micron, Cl 2ppm, SO_FourIt was 3 ppm. Comparative Example 1 The pH 6.51 solution obtained in step (a) described in Example 1 above was used.
Put lycasol in a glass container and heat it at 50 ° C for 5 hours.
Was. The obtained silica sol had a pH of 6.53 and a viscosity of 3.8.
c. p. , With a particle size (BET method) of 13.7 mm
there were. 1000 g of this silica sol is converted to a cation exchange resin
(Amberlite IR-120B) packed column
At room temperature at a space velocity of 4 per hour.
1020 g of kasol was obtained. This acidic silica sol has a specific gravity of 1.126, p
H2.68, viscosity 1.7c. p. , SiO_Two20.0 weight
Amount%, Al_TwoO_Three234 ppm, Al_TwoO_Three/ SiO_Two
Molar ratio 0.00068, Na_TwoO (flame light method) 260pp
m, conductivity 810 μs / cm, particle diameter (BET method) 1
3.7 mm, particle diameter (dynamic light scattering method) 32 mm
Micron, Cl 2ppm, SO_FourIt was 3 ppm. Comparative Example 2 The acidic silica described in the preparation of the raw material silica sol in the above example was used.
Cazol was used as Comparative Example 2. Thermal stability of acidic silica sols of Examples and Comparative Examples The acidic silica sols of Examples 1 to 3 and Comparative Examples 1 and 2 were
After sealing in a storage container and preventing evaporation,
1 month and 3 months after leaving in a constant temperature bath
Measurement of the viscosity and pH of the gel and observation of gelation
Was. The results are shown in Table 1.   Table 1   ─────────────────────────────────                       80 ℃ 1 month 80 ℃ 3 months               ───────────────────────────                   pH viscosity pH viscosity   ─────────────────────────────────     Example 1 3.62 3.4 3.71 3.5           2 3.60 2.5 3.65 3.1           3 3.73 3.7 5.09 4.9     Comparative Example 1 6.32 Gelling in 12 days           2 5.684 Gelling in 4 days   ───────────────────────────────── As shown in the results in Table 1, the acidic silica sols of Examples 1 to 3
Surprisingly, even when left at 80 ° C for 3 months,
The degree of increase was very small and stable. Generally, one month at 60 ° C. is equivalent to one year at room temperature.
Therefore, 3 months at 80 ° C will be more than 3 years at room temperature,
The acidic silica sols of Examples 1 to 3 are alkaline silica sols.
It can be said that it shows the same stability as. [0044] According to the method of the present invention, colloidal silica
Mosquito has a particle size of 4-30 millimicrons and a pH of 2-
5. Efficient production of stable acidic silica sol as an industrial product
Can be produced. The acidic silicic acid produced according to the present invention
Kasol has aluminum content of Al_TwoO_Three/ SiO_TwoMo
In the ratio of 0.0006 to 0.0035,
Aluminosilicate sufficient to stabilize silica sol
Sites are firmly formed on the colloidal silica surface
Very stable and equivalent to alkaline silica sol
It has the stability of Therefore, this acidic silica sol is generally used in accordance with
Applications of acidic silica sol that has been used since, for example,
Metal surface treatment agent, coating agent, paint, hard coat
Agents, binders, abrasives for semiconductor surfaces, glass fibers, etc.
For any surface treatment agent, ceramic fiber raw material, etc.
Not only helps to stabilize performance and improve performance
Difficult to use with conventional acidic silica sol
It can be used for any purpose.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuyoshi Hamada 11-1, Kita-sode, Sodegaura-shi, Chiba Nissan Chemical Industry Co., Ltd. Sodegaura Plant (56) References JP-A-58-110415 Kaikai 64-72913 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C01B 33/12

Claims (1)

(57) [Claim 1] Colloidal silica having a particle diameter of 4 to 30 mm and a pH of 2 to 5 comprising the following steps (a), (b) and (c): A method for producing a stable acidic silica sol. (A) the particle size of the colloidal silica is 4 to 30 millimicrons and a pH of Ri 2-9 der, and aluminum
The content of Al ₂ O ₃ / SiO _{2 in a} molar ratio of 0 to 0.00
08 in a silica sol having a ratio of Al ₂ O ₃ / SiO
₂ mole ratio exceeds 0.0006, but such that more than 0.004, the step of adding an alkali aluminate solution, silica sol obtained by (b) above (a) step 80
(C) contacting the silica sol obtained in the above step (b) with a cation exchange resin or a cation exchange resin and an anion exchange resin to adjust the pH. A step of producing 2 to 5 acidic silica sols.