Claims
- 1. A method for preparing a stable alkaline aqueous silica sol having an SiO.sub.2 concentration of from 1 to 6% by weight, in which the colloidal particles of said silica have a particle size of 40 to 300 millimicrons as measured by dynamic light-scattering, and have an elongated shape having a uniform thickness of 5 to 20 millimicrons and an elongation of 5 to 30 times the thickness in only one plane, comprising the following steps (a), (b) and (c):
- (a) mixing at a temperature of 2.degree. to 50.degree. C. an aqueous solution containing at least one compound selected from the group consisting of water-soluble calcium salt and magnesium salt with an aqueous colloidal liquid of an active silicic acid containing from 1 to 6% by weight of SiO.sub.2 but not containing colloidal silica particles having a size larger than 3 millimicrons and having a pH value of from 2 to 4 in an amount of from 1500 to 8500 ppm as a weight ratio of CaO or MgO or a mixture thereof with respect to SiO.sub.2 of the said active silicic acid;
- (b) mixing at 2.degree. to 50.degree. C. an aqueous solution of at least one compound selected from the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water-soluble silicates of water-soluble organic base with the aqueous solution obtained in step (a) in a molar ratio of SiO.sub.2 /M.sub.2 O from 20 to 200, where SiO.sub.2 indicates the total silica content derived form said active silicic acid and the silica content of said water-soluble silicate, and M indicates an alkali metal atom of said alkali metal hydroxide or an organic base molecule of said water-soluble organic base; and
- (c) heating the mixture obtained step (b) at 60.degree. to 150.degree. C. for 0.5 to 40 hours.
- 2. The method of claim 1 for preparing a stable alkaline aqueous silica sol, wherein said active silicic acid-containing aqueous colloidal liquid to be used in step (a) is one obtained by bringing an aqueous solution of sodium water glass having a molar ratio of SiO.sub.2 /Na.sub.2 O from 1 to 4.5 and an SiO.sub.2 concentration of from 1 to 6% by weight into contact with a hydrogen type cationic exchange resin.
- 3. The method of claim 1 for preparing a stable alkaline aqueous silica sol, wherein said aqueous solution in step (a) comprises at least one compound selected from the group consisting of calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium sulfate, calcium sulfamate, magnesium sulfamate, calcium formate, magnesium formate, calcium acetate and magnesium acetate in an amount of from 2 to 20% by weight.
- 4. The method of claim 1 for preparing a stable alkaline aqueous silica sol, wherein said at least one compound in step (b) comprises at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, propanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
- 5. A method for preparing a stable alkaline aqueous silica sol having an SiO.sub.2 concentration of from 1 to 6% by weight, in which the colloidal particles of said silica have a particle size of 40 to 300 millimicrons as measured by dynamic light-scattering, and have an elongated shape having a uniform thickness of 5 to 20 millimicrons and an elongation of 5 to 30 times the thickness in only one plane, comprising the following steps (a), (b) and (c):
- (a) mixing at a temperature of 2.degree. to 50.degree. C. an aqueous solution containing at least one compound selected from the group consisting of water-soluble calcium salt and magnesium salt with an aqueous colloidal liquid of an active silicic acid containing from 1 to 6% by weight of SiO.sub.2 but not containing colloidal silica particles having a size larger than 3 millimicrons and having a pH value higher than 4 and up to 5 in an amount of from 1500 to 8500 ppm as a weight ratio of CaO or MgO or a mixture of said CaO and MgO to SiO.sub.2 of the said active silicic acid;
- (b) mixing at 2.degree. to 50.degree. C. an aqueous solution of at least one compound selected from the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water-soluble silicates of water-soluble organic base with the aqueous solution obtained in step (a) in a molar ration of SiO.sub.2 /M.sub.2 O from 20 to 200, where SiO.sub.2 indicates the total silica content derived from said active silicic acid and from said silicate, and M indicates an alkali metal atom of said alkali metal hydroxide or an organic base molecule of said organic base; and
- (c) heating the mixture obtained in step (b) at 60.degree. to 250.degree. C. for 0.5 to 40 hours.
- 6. The method of claim 5 for preparing a stable alkaline aqueous silica sol, wherein said active silicic acid-containing aqueous colloidal liquid to be used in step (a) is one obtained by bringing an aqueous solution of sodium water glass having a molar ratio of SiO.sub.2 /Na.sub.2 O from 1 to 4.5 and an SiO.sub.2 concentration of from 1 to 6% by weight into contact with a hydrogen type cationic exchange resin, said active silicic acid-containing aqueous colloidal liquid having an SiO.sub.2 concentration of from 1 to 6% by weight and a pH value higher than 4 and up to 5, and not containing colloidal silica particles having a particle size of 3 millimicrons or more.
- 7. The method of claim 5 for preparing a stable alkaline aqueous silica sol, wherein said aqueous solution in step (a) comprises at least one compound selected from the group consisting of calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium sulfate, calcium sulfamate, magnesium sulfamate, calcium formate, magnesium formate, calcium acetate and magnesium acetate in an amount of from 2 to 20% by weight.
- 8. The method of claim 5 for preparing a stable alkaline aqueous silica sol, wherein said at least one compound in step (b) comprises at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, propanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
- 9. A method for preparing a stable alkaline aqueous silica sol having an SiO.sub.2 concentration of from 1 to 30% by weight, in which the colloidal particles of said silica have a particle size of 40 to 300 millimicrons as measured by dynamic light-scattering, and have an elongated shape having a uniform thickness of 5 to 20 millimicrons and an elongation of 5 to 30 times the thickness in only one plane, comprising the following steps (a), (b), (c) and (d):
- (a) mixing at a temperature of 2.degree. to 50.degree. C. an aqueous solution containing at least one compound selected from the group consisting of water-soluble calcium salt and magnesium salt with an aqueous colloidal liquid of an active silicic acid containing from 1 to 6% by weight of SiO.sub.2 but not containing colloidal particles having a size larger than 3 millimicrons and having a pH value of from 2 to 4 in an amount of from 1500 to 8500 ppm as a weight ratio of CaO or MgO or a mixture thereof with respect to SiO.sub.2 of the said active silicic acid.
- (b) mixing at 2.degree. to 50.degree. C. an aqueous solution of at least one compound selected from the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water-soluble silicates of water-soluble organic base with the aqueous solution obtained in step (a) in a molar ratio of SiO.sub.2 /M.sub.2 O form 20 to 200, where SiO.sub.2 indicates the total silica content derived form said active silicic acid and the silica content of said water soluble silicate, and M indicates an alkali metal atom of said alkali metal hydroxide or an organic base molecule of said organic base; and
- (c) heating the mixture obtained in step (b) at 60.degree. to 150.degree. C. for 0.5 to 40 hours and then
- (d) removing anions and water from said silica sol prepared in step (c) to provide an anion concentration of 0.1% by weight or less and an SiO.sub.2 concentration of from 1 to 30% by weight.
- 10. The method of claim 9 for preparing a stable alkaline aqueous silica sol, wherein said removal of said anions and water is effected by ultrafiltration.
- 11. The method of claim 10 for preparing a stable alkaline aqueous silica sol, further including the step of adding at least one compound selected from the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water-soluble silicates of organic base to the silica sol obtained in step (d) so as to keep said molar ratio of SiO.sub.2 /M.sub.2 O in the sol within the range of from 20 to 200.
- 12. The method of claim 11 for preparing a stable alkaline aqueous silica sol, wherein said at least one compound in step (b) comprises at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, monopropanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
- 13. The method of claim 9 for preparing a stable alkaline aqueous silica sol, wherein said removal of said anions and said water is effected by treatment of said silica sol with a hydroxy type anionic exchange resin so as to remove said anions therefrom followed by evaporation of the resulting sol to remove said water therefrom.
- 14. The method of claim 9 for preparing a stable alkaline aqueous silicate sol, wherein the aqueous colloidal liquid of an active silicic acid in step (a) is one obtained by bringing an aqueous solution of sodium water glass having a molar ratio of SiO.sub.2 /Na.sub.2 O from 1 to 4.5 and an SiO.sub.2 concentration of from 1 to 6% by weight into contact with a cationic exchange resin in the hydrogen form.
- 15. The method of claim 9 for preparing a stable alkaline aqueous silica sol, wherein the water-soluble salt of calcium or magnesium in step (a) is at least one selected from the group consisting of calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium sulfate, calcium sulfamate, magnesium sulfamate, calcium formate, magnesium formate, calcium acetate, and magnesium acetate.
- 16. The method of claim 9 for preparing a stable alkaline aqueous silica sol, wherein the compound in step (b) is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethyldiethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, propanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
- 17. A method for preparing a stable alkaline aqueous silica sol having an SiO.sub.2 concentration of from 0.5 to 25% by weight, in which the colloidal particles of said silica have a particle size of 40 to 500 millimicrons as measured by dynamic light-scattering, and have an elongated shape having a uniform thickness of 5 to 40 millimicrons and an elongation of 5 to 30 times the thickness in only one plane, comprising the following steps (a'), (b') and (c'):
- (a') mixing at a temperature of 2.degree. to 50.degree. C. an aqueous solution containing at least one compound selected from the group consisting of water-soluble calcium salt and magnesium salt with an aqueous acidic silica sol containing colloidal silica particles having an average particle diameter of from 3 to 30 millimicrons, said acidic silica sol having from 0.5 to 25% of SiO.sub.2 by weight and having a pH value of from 1 to 5, in an amount of from 0.15 to 1.00% by weight of CaO, MgO or a mixture of said CaO and MgO to SiO.sub.2 of said acidic silica sol;
- (b') mixing at 2.degree. to 50.degree. C. an aqueous solution of at least one compound selected form the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water-soluble silicates of organic base with said liquid as obtained in step (a') in a molar ratio of SiO.sub.2 /M.sub.2 O from 20 to 300, where SiO.sub.2 indicates the total silica content derived from said acidic silica sol and from said silicate, and M indicates an alkali metal atom of the said alkali metal hydroxide or an organic base molecule of said organic base; and
- (c') heating the mixture obtained in step (b') at 60.degree. to 300.degree. C. for 0.5 to 40 hours to form said colloidal silica particles in said heated mixture having an elongated shape and having a thickness larger than the particle size of said colloidal silica particles of said step (a').
- 18. The method of claim 17 for preparing a stable alkaline aqueous silica sol, wherein said aqueous solution in step (a') comprises at least one compound selected from the group consisting of calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium sulfate, calcium sulfamate, magnesium sulfamate, calcium formate, magnesium formate, calcium acetate and magnesium acetate in an amount of from 2 to 20% by weight of said aqueous solution.
- 19. The method of claim 17 for preparing a stable alkaline aqueous silica sol, wherein said at least one compound in step (b') comprises at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, monopropanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
- 20. A method for preparing a stable alkaline aqueous silica sol having an SiO.sub.2 concentration of from 1 to 40% by weight, in which the colloidal particles of said silica have a particle size of 40 to 500 millimicrons as measured by dynamic light-scattering, and have an elongated shape having a uniform thickness of 5 to 40 millimicrons and an elongation of 5 to 30 times the thickness in only one plane, comprising the following steps (a'), (b'), (c') and (d'):
- (a') mixing at a temperature of 2.degree. to 50.degree. C. an aqueous solution containing at least one compound selected from the group consisting of water-soluble calcium salt and magnesium salt with an aqueous acidic silica sol containing colloidal silica particles having an average particle diameter of from 3 to 30 millimicrons, said acidic silica sol having from 0.5 to 25% of SiO.sub.2 by weight and having a pH value of from 1 to 5, in an amount of from 0.15 to 1.00% by weight of CaO, MgO or a mixture of said CaO and MgO to SiO.sub.2 of said acidic silica sol;
- (b') mixing at 2.degree. to 50.degree. C. an aqueous solution of at least one compound selected from the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water-soluble silicates of organic base with said liquid as obtained in step (a') in a molar ratio of SiO.sub.2 /M.sub.2 O from 20 to 300, where SiO.sub.2 indicates the total silica content derived from said acidic silica sol and from said silicate, and M indicates an alkali metal atom of the said alkali metal hydroxide or an organic base molecule of said organic base; and
- (c') heating the mixture obtained in step (b') at 60.degree. to 300.degree. C. for 0.5 to 40 hours to form said colloidal silica particles in said heated mixture having an elongated shape and having a thickness larger than the particle size of said colloidal silica particles of said step (a'), and then
- (d') removing anions and water from said silica sol prepared in step (c') such that the anion concentration is 0.1% by weight or less and the SiO.sub.2 concentration of said silica sol is from 1 to 40% by weight.
- 21. The method of claim 20 for preparing a stable alkaline aqueous silica sol, wherein said removal of said anions and water is effected by ultrafiltration.
- 22. The method of claim 21 for preparing a stable alkaline aqueous silica sol, further including the step of adding at least one compound selected from the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water soluble silicates of organic base to the silica sol obtained in step (d') so as to keep said molar ratio of SiO.sub.2 /M.sub.2 O in the sol within the range of from 20 to 300.
- 23. The method of claim 22 for preparing a stable alkaline aqueous silica sol, wherein the compound added to the silica sol obtained in step (d') is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethyldiethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, propanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
- 24. The method of claim 20 for preparing a stable alkaline aqueous silica sol, wherein said at least one compound in step (b') comprises at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, monopropanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
- 25. The method of claim 20 for preparing a stable alkaline aqueous silica sol, wherein said removal of said anions and said water is effected by treating said silica sol with a hydroxy type anionic exchange resin to remove the anions therefrom followed by evaporating the resulting silica sol to remove water therefrom.
- 26. The method of claim 20 for preparing a stable alkaline silica sol, wherein said aqueous solution of water-soluble salt of calcium or magnesium comprises at least one compound selected from the group consisting of calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium sulfate, calcium sulfamate, magnesium sulfamate, calcium formate, magnesium formate, calcium acetate, and magnesium acetate.
- 27. A method for preparing a stable alkaline aqueous silica sol having an SiO.sub.2 concentration of from 1 to 30% by weight, in which the colloidal particles of said silica have a particle size of 40 to 300 millimicrons as measured by dynamic light-scattering, and have an elongated shape having a uniform thickness of 5 to 20 millimicrons and an elongation of 5 to 30 times the thickness in only one plane, comprising the follow steps (a), (b), (c), and (d):
- (a) mixing an aqueous solution of at least one compound selected from the groups consisting of water-soluble salt of calcium or magnesium with an aqueous colloidal liquid of an active silicic acid containing from 1 to 6% by weight of SiO.sub.2 and not containing colloidal silica particles having a size larger than 3 millimicrons and having a pH value higher than 4 and up to 5 in an amount of from 1500 to 8500 ppm as a weight ratio of CaO or MgO or a mixture thereof with respect to SiO.sub.2 of the said active silicic acid at a temperature of 2.degree. to 50.degree. C.;
- (b) mixing an aqueous solution of at least one compound selected from the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water-soluble silicates of water-soluble organic base with the liquid obtained in step (a) in a molar ratio of SiO.sub.2 /M.sub.2 O from 20 to 200, where SiO.sub.2 indicates the total silica content derived from said active silicic acid and the silica content of said water-soluble silicate, and M indicates an alkali metal atom of said alkali metal hydroxide or an organic base molecule of said water-soluble organic base at 2.degree. to 50.degree. C.;
- (c) heating the liquid obtained in step (b) at 60.degree. to 250.degree. C. for 0.5 to 40 hours, whereby to form a stable sol of colloidal silica; and then
- (d) removing anions and water from the sol obtained in step (c) to provide an anion concentration of 0.1% by weight or less and an SiO.sub.z concentration of from 1 to 30% by weight in the sol.
- 28. The method of claim 27 for preparing a stable alkaline aqueous silica sol, wherein the aqueous colloidal liquid of an active silicic acid in step (a) is one obtained by bringing an aqueous solution of sodium water glass having a molar ratio of SiO.sub.2 /Na.sub.2 O from 1 to 4.5 and an SiO.sub.2 concentration of from 1 to 6% by weight into contact with a cationic exchange resin in the hydrogen form.
- 29. The method of claim 27 for preparing a stable alkaline aqueous silica sol, wherein the water-soluble salt of calcium or magnesium in step (a) is at least one selected from the group consisting of calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, magnesium sulfate, calcium sulfamate, magnesium sulfamate, calcium formate, magnesium formate, calcium acetate, and magnesium acetate.
- 30. The method of claim 27 for preparing a stable alkaline aqueous silicic sol, wherein the compound in step (b) is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethyldiethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, propanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
- 31. The method of claim 27 for preparing a stable alkaline aqueous silica sol, further including a step of adding at least one compound selected from the group consisting of alkali metal hydroxides, water-soluble organic bases, water-soluble silicates of alkali metal hydroxide and water-soluble silicates of water-soluble organic base to the silica sol obtained in step (d) so as to keep said molar ratio of SiO.sub.2 /M.sub.2 O in the sol within the range of from 20 to 200.
- 32. The method of claim 31 for preparing a stable alkaline aqueous silica sol, wherein the compound added in said further step is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, tetraethanolammonium hydroxide, monomethyltriethanolammonium hydroxide, tetramethylammonium hydroxide, monoethanolamine, diethanolamine, triethanolamine, N,N-dimethyldiethanolamine, N-(.beta.-aminomethyl)ethanolamine, N-methylethanolamine, propanolamine, morpholine, silicates of organic base, sodium silicate and potassium silicate.
Priority Claims (1)
Number |
Date |
Country |
Kind |
63-62849 |
Mar 1988 |
JPX |
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Parent Case Info
This is a Division of application Ser. No. 07/324,446 filed Mar. 16, 1989 now abandon.
US Referenced Citations (9)
Non-Patent Literature Citations (2)
Entry |
Ogino et al, "Particle Growth in Silica Dispersion," Journal of Colloid and Interface Science, V. 56, No. 3, Sep. 1976, pp. 629-630. |
Koppel, "Analysis of Macromolecular Polydispersity," Journal of Chemical Physics, V. 57, No. 11, Dec. 1972, pp. 4814-4820. |
Divisions (1)
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Number |
Date |
Country |
Parent |
324446 |
Mar 1989 |
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