High pH silica-aluminum containing colloidal aqueous solution

Abstract

The objective is to develop a silica-aluminum-containing colloidal aqueous solution that is stable even at pH levels above 10. [Solution] This is a high-pH silica-aluminum-containing colloidal aqueous solution containing colloidal silica, aluminum, hydroxycarboxylic acid, and quaternary ammonium hydroxide as constituent components, and satisfying the following requirements [1] to [4]: ​​[1] pH is greater than 10 and not greater than 13; [2] the ratio A / B between the number of moles of SiO2 (A) and the number of moles of Al2O3 (B) is in the range of 0.01 to 1000; [3] the ratio C / B between the product (C) of the number of moles of hydroxycarboxylic acid and the number of carboxyl groups in the hydroxycarboxylic acid and B is in the range of 1 to 6; and [4] the ratio D / C between the number of moles of quaternary ammonium hydroxide (D) and C is in the range of 0.5 to 150.

Description

[Technical Field]

[0001] The present invention relates to a silica-aluminum-containing colloidal aqueous solution in the high pH range. [Background technology]

[0002] The present applicant has disclosed a silica-aluminum-containing colloidal aqueous solution in Patent Document 1. The components of the silica-aluminum-containing colloidal aqueous solution are colloidal silica, aluminum, an oxycarboxylic acid, and an alkali (excluding alkanolamine). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6249547 Summary of the Invention [Problem to be solved by the invention]

[0004] The silica-aluminum-containing colloidal aqueous solution described in Patent Document 1 was prone to precipitates and gelation regardless of the length of storage period when its pH exceeded 10. Therefore, it was difficult to apply it to applications requiring a pH range above 10.

[0005] An object of the present invention is to develop a silica-aluminum-containing colloidal aqueous solution that is stable even at a pH of more than 10. [Means for solving the problem]

[0006] The present inventors conducted extensive research into the above-mentioned problems and surprisingly found that by using quaternary ammonium hydroxide as the alkali, a silica-aluminum-containing colloidal aqueous solution can be obtained that has excellent stability in a pH range above 10. Furthermore, in Patent Document 1, the raw material silica sol could not be used as is and had to be diluted, so the only way to obtain a highly concentrated product was to first produce a silica-aluminum-containing colloidal aqueous solution and then concentrate it. However, the present inventors found that by using quaternary ammonium hydroxide, the raw material silica sol can be used as is, i.e., a highly concentrated silica-aluminum-containing colloidal aqueous solution can be produced without a concentration step. The present invention was made based on this finding.

[0007] The present invention is as follows. [1] A high-pH silica-aluminum-containing colloidal aqueous solution containing colloidal silica, aluminum, an oxycarboxylic acid, and a quaternary ammonium hydroxide as constituent components, and satisfying the following requirements [1] to [4]: [1] The pH is greater than 10 and less than 13. [2] The number of moles of SiO2 (A) and the number of moles of Al2O3 (B) is in the range of A / B = 0.01 to 1000. [3] The product (C) of the number of moles of hydroxycarboxylic acid and the number of carboxyl groups in the hydroxycarboxylic acid and the above B is in the range of C / B=1 to 6. [4] The molar number (D) of the quaternary ammonium hydroxide and the above C are in the range of D / C=0.5 to 150. [2] A powder obtained by drying the high pH silica-aluminum-containing colloidal aqueous solution described in [1] above. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in detail below based on preferred embodiments, but the present invention is not limited to the following embodiments and various modifications are possible within the scope of the claims. In the present invention, the expression "numeric value 1 to numerical value 2" in relation to a numerical range means a numerical range including both the numerical values ​​1 and 2, with numerical value 1 being the lower limit and numerical value 2 being the upper limit, and is synonymous with "numerical value 1 or more and numerical value 2 or less."

[0009] The high-pH silica-aluminum-containing colloidal aqueous solution of the present invention (hereinafter also referred to as "the aqueous solution of the present invention") contains colloidal silica, aluminum, an oxycarboxylic acid, and a quaternary ammonium hydroxide as constituent components, and satisfies the following conditions [1] to [4]. [1] The pH is greater than 10 and less than 13. [2] The number of moles of SiO2 (A) and the number of moles of Al2O3 (B) is in the range of A / B = 0.01 to 1000. [3] The product (C) of the number of moles of hydroxycarboxylic acid and the number of carboxyl groups in the hydroxycarboxylic acid and the above B is in the range of C / B=1 to 6. [4] The molar number (D) of the quaternary ammonium hydroxide and the above C are in the range of D / C=0.5 to 150.

[0010] (Constituents) The colloidal silica is not particularly limited as long as it is derived from an acidic to alkaline silica sol. The particle shape is also not particularly limited as long as it is known in the art. In addition, it is preferably derived from a silica sol of an aqueous solvent.

[0011] Suitable examples of hydroxycarboxylic acids include lactic acid, citric acid, malic acid, tartaric acid, glycolic acid, etc., with lactic acid being particularly preferred.

[0012] Examples of quaternary ammonium hydroxides include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylpropylammonium hydroxide, dimethyldiethylammonium hydroxide, choline, etc. Among these, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline are recommended because they are particularly effective in stabilizing dispersion and are easily available.

[0013] The aqueous solution of the present invention may contain ammonia within a range that does not impair stability, but is preferably substantially free of ammonia. Here, "substantially free of ammonia" means that the aqueous solution does not contain ammonia except for ammonia derived from impurities in the raw materials. More preferably, the aqueous solution of the present invention is completely free of ammonia.

[0014] The aqueous solution of the present invention may contain alkali metals and alkaline earth metals within the range that does not impair stability. However, the amount of alkali metals contained in the silica sol, which is the raw material for colloidal silica, does not pose any particular problem.

[0015] (Requirement 1) The aqueous solution of the present invention has a pH in the range of more than 10 and not more than 13. Within this range, the aqueous solution of the present invention is highly stable because precipitation is unlikely to occur. The lower limit of the above pH range is preferably 10.1, more preferably 10.2, even more preferably 10.3, still more preferably 10.4, particularly preferably 10.5, and especially more preferably 11. Therefore, preferred pH ranges include 10.1 to 13, 10.2 to 13, 10.3 to 13, 10.4 to 13, 10.5 to 13, and 11 to 13.

[0016] (Requirement 2) In the aqueous solution of the present invention, the ratio A / B is in the range of 0.01 to 1000, where A is the number of moles of SiO2 and B is the number of moles of Al2O3. It is presumed that when A / B is close to the lower limit, ionic aluminum, aluminum-modified colloidal silica, and alumina sol (colloidal alumina) coexist, while when A / B is close to the upper limit, colloidal silica predominates, with aluminum-modified colloidal silica and ionic aluminum present in part. The aqueous solution of the present invention allows A / B to take on a wide range, as described above, because the quantitative ratios of aluminum, hydroxycarboxylic acid, and quaternary ammonium hydroxide are defined by C / B in Requirement 3 and D / C in Requirement 4.

[0017] (Requirement 3) In the aqueous solution of the present invention, when the product of the number of moles of hydroxycarboxylic acid and the number of carboxyl groups in the hydroxycarboxylic acid is C, the relationship between C and the above-mentioned B (the number of moles of Al2O3) is in the range of C / B = 1 to 6. If C / B is less than 1, the amount of hydroxycarboxylic acid required to stabilize the aluminum component will be insufficient, and for example, precipitation of aluminum hydroxide may occur. On the other hand, even if C / B is greater than 6, the aqueous solution will exhibit similar physical properties to those of the aqueous solution of the present invention as long as D / C is within the range of 0.5 to 150. However, considering the use of the aqueous solution of the present invention in a calcination treatment, a lower organic acid content is preferred.

[0018] In the aqueous solution of the present invention, the molar number of quaternary ammonium hydroxide is D, and the relationship with the above C (the product of the molar number of hydroxycarboxylic acid and the number of carboxyl groups in the hydroxycarboxylic acid) is D / C = 0.5 to 150. If D / C is below 0.5 or above 150, precipitation and gelation are likely to occur regardless of the length of storage period. The appropriate range of D / C tends to vary depending on A / B; for example, the higher the A / B, the higher the D / C is preferred, and the lower the A / B, the lower the D / C is preferred.

[0019] Depending on C / B and D / C, the range of D / B is 0.5 to 900, and the aqueous solution of the present invention can be obtained even within this D / B range.

[0020] The total SiO2 concentration and Al2O3 concentration of the aqueous solution of the present invention (hereinafter referred to as the "SiO2-Al2O3 total concentration") varies depending on the ratio of SiO2 to Al2O3 and cannot be generalized. However, as a guideline, when the SiO2 ratio is high, the SiO2-Al2O3 total concentration is preferably 50 mass% or less, more preferably 40 mass% or less, and even more preferably 35 mass% or less. When the Al2O3 ratio is high, the SiO2-Al2O3 total concentration is preferably 20 mass% or less. Furthermore, when the ratios of SiO2 and Al2O3 are equal, the SiO2-Al2O3 total concentration is preferably 30 mass% or less. In each of the above cases, if the SiO2-Al2O3 total concentration exceeds the above value, the viscosity increases and handling tends to deteriorate. In any of the above cases, there is no particular lower limit for the SiO2-Al2O3 total concentration, but from an economical standpoint, it is preferably 1 mass% or less, and more preferably 3 mass%.

[0021] The aqueous solution of the present invention can be used after being concentrated by ultrafiltration or heating, etc., as needed, or after being diluted with water, etc. However, since ultrafiltration cannot recover all of the aluminum component, concentration by heating is preferred.

[0022] The aqueous solution of the present invention has a transparent to milky white appearance, and no precipitate is observed. The appearance tends to become milky white as the proportion of silica increases.

[0023] The aqueous solution of the present invention is excellent in long-term storage stability, showing no change when stored at room temperature or even at 50°C for at least one month.

[0024] The viscosity of the aqueous solution of the present invention is not particularly limited as long as it maintains an appropriate fluidity as a solution, but the viscosity at 25°C measured with an E-type viscometer is preferably 100 mPa s or less, more preferably 50 mPa s or less, and even more preferably 10 mPa s or less.

[0025] As described above, the aqueous solution of the present invention has excellent storage stability and allows the composition ratio of the silica component to the aluminum component to be set over a wide range, making it suitable for applications requiring a high pH, ​​such as surface treatment agents or additives for optical materials, electronic materials, zinc-plated steel sheets, electromagnetic steel sheets, etc., various binders for ceramic fiber molding and refractories, coating agents, carriers for catalysts, etc., and ink-receiving layers for inkjet recording media.

[0026] (Manufacturing method) The method for producing the aqueous solution of the present invention will be described. In this production method, since there is substantially no loss of components outside the system, the amounts of components derived from the raw materials are retained in the final product. Therefore, the composition ratio of the aqueous solution of the present invention is the ratio of the components derived from the raw materials.

[0027] The method for producing the aqueous solution of the present invention comprises mixing silica sol with an aqueous solution of a quaternary ammonium hydroxide and an aluminum salt of an oxycarboxylic acid, followed by heating.

[0028] In this manufacturing method, as long as it can prevent aggregation or precipitation due to the reaction between silica sol and hydroxycarboxylic acid, there is no particular limitation on the mixing method.The mixing method can be, for example, (a) a method of simultaneously adding silica sol, quaternary ammonium hydroxide, and an aqueous solution of aluminum salt of hydroxycarboxylic acid; (b) a method of mixing silica sol and quaternary ammonium hydroxide, and then adding an aqueous solution of aluminum salt of hydroxycarboxylic acid; (c) a method of mixing an aqueous solution of aluminum salt of hydroxycarboxylic acid and quaternary ammonium hydroxide, and then adding silica sol; (d) a method of mixing silica sol and an aqueous solution of aluminum salt of hydroxycarboxylic acid, and then adding quaternary ammonium hydroxide.

[0029] Since the quaternary ammonium hydroxide is thought to prevent aggregation and precipitation due to the reaction between silica sol and hydroxycarboxylic acid, it is desirable to appropriately set conditions such as the concentration of raw material components and stirring strength depending on the mixing order in any of the above mixing methods. Of the above mixing methods, methods (b) and (c) are more preferred because they allow the quaternary ammonium hydroxide to be present in the reaction between silica sol and hydroxycarboxylic acid. Furthermore, methods (b), (c), and (d) allow the silica sol to be used as a raw material without dilution, making them suitable for producing a highly concentrated aqueous solution of the present invention.

[0030] Next, the raw materials used in the first production method will be described. The silica sol may be either acidic or alkaline, and may be produced by a known method or a commercially available ordinary silica sol product. The particle shape is not particularly limited as long as it is known in the art. Furthermore, silica sol in an aqueous solvent, so-called aqueous silica sol, is preferred. Specific examples of silica sol include the Snowtex series manufactured by Nissan Chemical Industries, Ltd., the Cataloid series manufactured by JGC Catalysts and Chemicals, and silica sols sold by Nippon Chemical Industry Co., Ltd. Generally, when an acidic silica sol is used, the content of Na and the like is significantly reduced, so it can be selected according to the application.

[0031] Specific examples of the quaternary ammonium hydroxide are, as above, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylpropylammonium hydroxide, dimethyldiethylammonium hydroxide, choline, etc.

[0032] The aqueous solution of an aluminum salt of an oxycarboxylic acid is an aqueous solution containing an oxycarboxylic acid and ionic aluminum. Specific examples of the oxycarboxylic acid are, as described above, lactic acid, citric acid, malic acid, tartaric acid, glycolic acid, etc. Examples of the aluminum salt of an oxycarboxylic acid include aluminum lactate, aluminum citrate, aluminum malate, basic aluminum lactate, aluminum citrate lactate, aluminum glycolate lactate, and aluminum glycolate, and one or more of these may be used. The ratio of the oxycarboxylic acid to aluminum in the aqueous solution of an aluminum salt of an oxycarboxylic acid is within the above-mentioned C / B range, i.e., C / B = 1 to 6. The aqueous solution of an aluminum salt of an oxycarboxylic acid may contain inorganic acid radicals derived from the raw materials used for production, inorganic acid radicals added to stabilize the aqueous solution, etc.

[0033] Here, specific examples of aqueous solutions of aluminum salts of hydroxycarboxylic acids will be described, including aqueous solutions of aluminum lactate and basic aluminum lactate, in which the hydroxycarboxylic acid is lactic acid. These solutions may be commercially available industrial chemicals, or may be prepared by known production methods. For example, an aqueous solution of aluminum lactate may be prepared by dissolving commercially available aluminum lactate (C / B = 6), or a commercially available aqueous solution of basic aluminum lactate (e.g., Taxeram (registered trademark), manufactured by Taki Chemical Industry Co., Ltd., pH 4-5, C / B = 1.5-1.6, Al2O3 concentration = 8-9% by mass) may be used. Examples of known production methods include those disclosed in Japanese Patent Publication Nos. 58-5174 and 59-40381, which disclose methods for producing basic aluminum lactate. Among these, solutions with a C / B = 1-2 are suitable for use in the present invention due to their high stability as basic salts.

[0034] The mixing ratio of silica sol to the aqueous solution of aluminum salt of hydroxycarboxylic acid is in the range of A / B = 0.01 to 1000. The reason why a stable aqueous solution of the present invention can be obtained over such a wide range of A / B is thought to be the presence of quaternary ammonium hydroxide in the reaction between silica sol and hydroxycarboxylic acid, as described above. Considering this in more detail, it is presumed that colloidal silica and a portion of the ionic aluminum derived from the aqueous solution of aluminum salt of hydroxycarboxylic acid exist as aluminum-modified colloidal silica via the quaternary ammonium hydroxide. Furthermore, it is presumed that the remaining ionic aluminum is stabilized by hydroxycarboxylic acid (and alumina sol is also present when the aluminum content is high, etc.), which contributes to improved stability.

[0035] The heating temperature after mixing is preferably 90 to 200°C, more preferably 90 to 140°C. Heating provides high stability. There are no particular limitations on the heating method, and examples include ordinary heating methods and autoclaving. Since the particle size of the particles in the aqueous solution of the present invention tends to increase with increasing heat, it is preferable to appropriately set the heating conditions (temperature, time, etc.) depending on the desired particle size. The heating time may be appropriately set, and is preferably, for example, 1 to 10 hours.

[0036] The aqueous solution of the present invention can be dried to produce a redispersible silica-aluminum-containing colloidal powder. "Redispersible" means that the powder reverts to the aqueous solution of the present invention when suspended in water. The powder can be used as is, or at a high concentration by dispersing it in a small amount of water. Conventional drying methods, such as spray drying, static drying, and flash drying, can be used. A drying temperature of 150°C or less is preferred. [Example]

[0037] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. As the silica sol, Cataloid SN manufactured by JGC Catalysts and Chemicals Co., Ltd. and Snowtex C manufactured by Nissan Chemical Industries, Ltd. were used.

[0038] Example 1 0.09 parts by mass of Cataloid SN (SiO = 20% by mass, NaO = 0.025% by mass, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. was mixed with 16.00 parts by mass of 35% TEAH, and then 33.25 parts by mass of a basic aluminum lactate aqueous solution (AlO = 9.2% by mass, lactic acid = 10.2% by mass, pH 4) was slowly added. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 0.01, C / B = 1.25, D / C = 1.01, SiO2 = 0.04 mass%, Al2O3 = 6.23 mass%, pH 12.8, and EC 37.4 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0039] Example 2 15.1 parts by mass of Cataloid SN (SiO = 20% by mass, NaO = 0.025% by mass, pH 3) manufactured by JGC Catalysts and Chemicals, Ltd. was mixed with 11.3 parts by mass of ion-exchanged water and 0.1 part by mass of a basic aluminum lactate aqueous solution (AlO = 9.2% by mass, lactic acid = 10.2% by mass, pH 4) under stirring, and then 3.60 parts by mass of 35% TEAH was slowly added. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 999, C / B = 1.25, D / C = 133, SiO2 = 10.3 mass%, Al2O3 = 0.0175 mass%, pH 11.9, and EC 11.4 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0040] Example 3 0.09 parts by mass of Cataloid SN (SiO = 20% by mass, NaO = 0.025% by mass, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. was mixed with 33.25 parts by mass of a basic aluminum lactate aqueous solution (AlO = 9.2% by mass, lactic acid = 10.2% by mass, pH 4) under stirring, and then 15.00 parts by mass of 35% TEAH was slowly added. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 0.01, C / B = 1.25, D / C = 0.95, SiO2 = 0.04 mass%, Al2O3 = 6.36 mass%, pH 10.6, and EC 35.6 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0041] Example 4 15.1 parts by mass of Cataloid SN (SiO = 20% by mass, NaO = 0.025% by mass, pH 3) manufactured by JGC Catalysts and Chemicals, Ltd. was mixed with 11.6 parts by mass of ion-exchanged water and 0.1 part by mass of a basic aluminum lactate aqueous solution (AlO = 9.2% by mass, lactic acid = 10.2% by mass, pH 4) under stirring, and then 3.30 parts by mass of 35% TEAH was slowly added. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 999, C / B = 1.25, D / C = 122, SiO2 = 10.3 mass%, Al2O3 = 0.0175 mass%, pH 10.9, and EC 10.6 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0042] Example 5 A solution obtained by diluting 4.9 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4) with 15.9 mass parts of ion-exchanged water was added, and 23.5 mass parts of Cataloid SN (SiO2 = 20 mass%, Na2O = 0.025 mass%, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. and 5.63 mass parts of 35% TEAH were simultaneously added and mixed. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 18, C / B = 1.25, D / C = 2.40, SiO2 = 9.4 mass%, Al2O3 = 0.91 mass%, pH 11.0, and EC 10.2 mS / cm. The aqueous solutions were also concentrated immediately after production using an evaporator to SiO2-Al2O3 total concentrations of 15, 20, 30, 40, and 50% by mass. The viscosities of the resulting high-pH silica-aluminum-containing colloidal aqueous solutions were 2.3 mPa·s, 2.9 mPa·s, 7.3 mPa·s, 32.1 mPa·s, and 5532 mPa·s, respectively. Even after one month of storage at room temperature, no gelation or precipitation was observed, and the solutions maintained their stability.

[0043] Example 6 4.9 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4) was added to 14.0 parts by mass of ion-exchanged water to form a solution, which was then stirred and mixed with 7.51 parts by mass of 35% TEAH, followed by 23.5 parts by mass of Cataloid SN (SiO2 = 20 mass%, Na2O = 0.025 mass%, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 18, C / B = 1.25, D / C = 3.20, SiO2 = 9.4 mass%, Al2O3 = 0.91 mass%, pH 12.9, and EC 11.7 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0044] Example 7 A solution of 3.9 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4) and 12.3 parts by mass of ion-exchanged water was added. While stirring the solution, 4.96 parts by mass of 35% TEAH was mixed, and then 18.8 parts by mass of Snowtex C (SiO2 = 20 mass%, Na2O = 0.034 mass%, pH 9) manufactured by Nissan Chemical Industries, Ltd. was mixed. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 18, C / B = 1.25, D / C = 2.64, SiO2 = 9.4 mass%, Al2O3 = 0.91 mass%, pH 10.2, and EC 11.2 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0045] Example 8 A solution of 2.9 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4), 1.13 parts by mass of 88% L-lactic acid, and 9.7 parts by mass of ion-exchanged water was added. While stirring, 3.64 parts by mass of 35% TEAH was added, and then 13.8 parts by mass of Cataloid SN (SiO2 = 20 mass%, Na2O = 0.025 mass%, pH 3) manufactured by JGC Catalysts and Chemicals, Ltd. was added. Next, this mixture was heated at 90°C for 1 hour to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 18, C / B = 5.45, D / C = 0.60, SiO2 = 9.1 mass%, Al2O3 = 0.86 mass%, pH 12.0, and EC 18.5 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0046] Example 9 A solution of 2.9 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4), 0.20 parts by mass of DL-malic acid, and 10.0 parts by mass of ion-exchanged water was added, and while stirring, 3.50 parts by mass of 35% TEAH was mixed, followed by 13.7 parts by mass of Cataloid SN (SiO2 = 20 mass%, Na2O = 0.025 mass%, pH 3) manufactured by JGC Catalysts and Chemicals, Ltd. Next, this mixture was hydrothermally treated at 110°C for 1 hour to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 18, C / B = 2.40, D / C = 1.34, SiO2 = 9.3 mass%, Al2O3 = 0.88 mass%, pH 11.1, and EC 16.1 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0047] Example 10 8.8 parts by mass of Cataloid SN (SiO = 20% by mass, NaO = 0.025% by mass, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. was mixed with 14.1 parts by mass of a basic aluminum lactate aqueous solution (AlO = 9.2% by mass, lactic acid = 10.2% by mass, pH 4) under stirring, and then 11.7 parts by mass of 35% TEAH was slowly added. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 2.3, C / B = 1.25, D / C = 1.74, SiO2 = 5.2 mass%, Al2O3 = 3.8 mass%, pH 12.8, and EC 22.4 mS / cm. Immediately after the preparation of the aqueous solution, after storage at 50°C for 1 month, and after storage at room temperature for 4 months, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0048] Example 11 12.7 parts by mass of Cataloid SN (SiO = 20% by mass, NaO = 0.025% by mass, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. was mixed with 5.3 parts by mass of a basic aluminum lactate aqueous solution (AlO = 9.2% by mass, lactic acid = 10.2% by mass, pH 4) under stirring, and then 5.4 parts by mass of 35% TEAH was slowly added. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 9.0, C / B = 1.25, D / C = 2.14, SiO2 = 11.1 mass%, Al2O3 = 2.1 mass%, pH 11.8, and EC 15.6 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0049] Example 12 18.8 parts by mass of Snowtex C (SiO2=20% by mass, Na2O=0.034% by mass, pH 9) manufactured by Nissan Chemical Industries, Ltd. was mixed with 3.9 parts by mass of a basic aluminum lactate aqueous solution (Al2O3=9.2% by mass, lactic acid=10.2% by mass, pH 4) under stirring, and then 5.0 parts by mass of 35% TEAH was slowly added. Next, this mixture was hydrothermally treated at 140°C for 3 hours to obtain a high-pH silica-aluminum-containing colloidal aqueous solution with A / B = 18, C / B = 1.56, D / C = 2.12, SiO2 = 13.6 mass%, Al2O3 = 1.3 mass%, pH 11.2, and EC 11.2 mS / cm. Immediately after the preparation of the aqueous solution, and even after storage at 50°C for 1 month, no gelation or precipitation was observed by visual observation, and the aqueous solution maintained its stability.

[0050] (powder) The high-pH silica-aluminum-containing colloidal aqueous solution obtained in Example 5 was dried at 100°C in a forced-air dryer to obtain a powder. When ion-exchanged water was added to this powder so that the concentration was the same as before drying and the powder was dispersed, the Tyndall phenomenon was observed and the pH was 11.0. This indicates that a dispersion of this powder in water exhibits the properties of the high-pH silica-aluminum-containing colloidal aqueous solution of the present invention.

[0051] Comparative Example 1 A solution was prepared by adding 26.4 parts by mass of ion-exchanged water to 0.3 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4), and while stirring, 2.0 parts by mass of 23% ammonia water as NH3 was mixed in, followed by 1.4 parts by mass of Cataloid SN (SiO2 = 20 mass%, Na2O = 0.025 mass%, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. Next, this mixture was subjected to hydrothermal treatment at 140°C for 3 hours. After the hydrothermal treatment, a white precipitate was observed, and a high-pH silica-aluminum-containing colloidal aqueous solution was not obtained. The raw material composition was A / B=19, C / B=1.6, D / C=70.8, SiO2=0.9 mass%, Al2O3=0.08 mass%, and the pH after hydrothermal treatment was 10.2 and EC was 0.8 mS / cm.

[0052] Comparative Example 2 A solution was prepared by adding 28.3 parts by mass of ion-exchanged water to 0.3 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4), and while stirring, 0.1 parts by mass of monoisopropanolamine (MIPA) was mixed, followed by 1.4 parts by mass of Cataloid SN (SiO2 = 20 mass%, Na2O = 0.025 mass%, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. Next, this mixture was hydrothermally treated at 140°C for 3 hours, but gelation occurred after the hydrothermal treatment, and a high-pH silica-aluminum-containing colloidal aqueous solution was not obtained. The raw material ratios were A / B=19, C / B=1.6, D / C=2.1, SiO2=0.9 mass%, and Al2O3=0.08 mass%.

[0053] Comparative Example 3 A solution of 14.1 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4) and 1.1 parts by mass of ion-exchanged water was added. While stirring the solution, 6.0 parts by mass of 35% TEAH was mixed, and then 8.8 parts by mass of Snowtex C (SiO2 = 20 mass%, Na2O = 0.034 mass%, pH 9) manufactured by Nissan Chemical Industries, Ltd. was mixed. Next, this mixture was hydrothermally treated at 140°C for 3 hours, but gelation occurred after the hydrothermal treatment, and a high-pH silica-aluminum-containing colloidal aqueous solution was not obtained. The raw material composition was A / B=2.3, C / B=1.6, D / C=0.72, SiO2=6.0 mass%, Al2O3=4.35 mass%, and the pH before hydrothermal treatment was 9.9.

[0054] Comparative Example 4 10.0 parts by mass of a basic aluminum lactate aqueous solution (Al2O3 = 9.2 mass%, lactic acid = 10.2 mass%, pH 4) was mixed with 12.5 parts by mass of 35% TEAH under stirring, and then 10.6 parts by mass of Cataloid SN (SiO2 = 20%, Na2O = 0.025%, pH 3) manufactured by JGC Catalysts and Chemicals Co., Ltd. was mixed. Next, this mixture was hydrothermally treated at 140°C for 3 hours. After the hydrothermal treatment, the mixture became cloudy and solid-liquid separation occurred, and a high-pH silica-aluminum-containing colloidal aqueous solution was not obtained. The raw material composition was A / B = 4.0, C / B = 1.6, D / C = 2.1, SiO2 = 6.6 mass%, Al2O3 = 2.78 mass%, the pH before hydrothermal treatment was 13.7, the pH after hydrothermal treatment was 13.2, and the EC was 22.2 mS / cm.

Claims

1. A high-pH silica-aluminum-containing colloidal aqueous solution containing colloidal silica, aluminum, an oxycarboxylic acid, and a quaternary ammonium hydroxide as constituent components, and satisfying the following requirements [1] to [4]. [1] The pH is greater than 10 and less than 13. [2] SiO 2 The number of moles (A) and Al 2 O 3 The number of moles (B) of A is in the range of A / B = 0.01 to 1000. [3] The product (C) of the number of moles of hydroxycarboxylic acid and the number of carboxyl groups in the hydroxycarboxylic acid and the above B is in the range of C / B=1 to 6. [4] The mole number (D) of quaternary ammonium hydroxide and the above C are in the range of D / C = 0.5 to 150.

2. A powder obtained by drying the high pH silica-aluminum-containing colloidal aqueous solution according to claim 1.