High-whiteness sodium aluminum silicate as well as preparation method and application thereof

Abstract

The invention discloses high-whiteness sodium aluminum silicate as well as a preparation method and application thereof. The preparation method comprises the following steps: adding an aluminum salt solution and water into a reaction kettle until the pH value is 4-6, stirring and heating to 45-65 DEG C; an aluminum salt solution and a sodium silicate solution are added for a reaction, the pH value is 4-6, the temperature is 45-65 DEG C, and the reaction time is 10-30 min; continuously adding the sodium silicate solution until the pH value is adjusted to 8-10; the sodium silicate solution and the aluminum salt solution are continuously added, the pH value is 8-10, the reaction is carried out for 50-70 min, and aging is carried out after flow merging is finished; adding a sulfuric acid solution, adjusting the pH value to 3.5-4.5, adding a masking agent, and stirring; and carrying out solid-liquid separation, washing, pulping and drying on the solution obtained in the previous step to obtain a high-whiteness sodium aluminum silicate product. The high-whiteness sodium aluminum silicate prepared by the method is high in whiteness and good in dispersity, and has the advantages of being simple in production process, low in cost and capable of realizing large-scale production.

Description

Technical Field

[0001] The invention relates to the field of silicate preparation, and in particular to high-white sodium aluminum silicate and a preparation method and application thereof. Background Art

[0002] Aluminum silicate mainly refers to a part of the silicon oxide tetrahedron replaced by aluminum oxide, and the ratio of silicon oxide to aluminum oxide is uncertain. There are many kinds of natural aluminum silicate, such as muscovite, analcime, etc.

[0003] In addition to natural aluminum silicates, there are many similar products that are synthesized artificially. Common methods include: calcining kaolin; activating clays such as kaolin with silicic acid and sodium hydroxide; precipitating aluminum salts in silica sol, co-gelling aluminum sol with silica sol, and then performing precipitation reaction.

[0004] As it is becoming increasingly difficult to obtain high-quality kaolin with low iron content, the "water washing-bleaching" process has to be used for impurity removal and purification. This process is extremely destructive to the ecological environment and water resources and does not meet the requirements of green development in today's society. The aluminum silicate produced by this method has low specific surface area and oil absorption value, and poor dispersibility in coatings, latex paints and other fields.

[0005] The disadvantage of chemical synthesis is that the required sol or emulsion exists only at the moment of preparation, and the powder obtained by subsequent drying can only be dispersed incompletely or requires a solvent mixture to achieve dispersion; another disadvantage is the aluminum silicate prepared using ion exchange resins. The resulting aluminum silicate has the required high purity, but cannot be dispersed. Summary of the invention

[0006] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the object of the present invention is to provide a method for preparing high-white sodium aluminum silicate, wherein the prepared sodium aluminum silicate has high whiteness and good dispersibility, and has the advantages of simple production process, low cost and large-scale production.

[0007] Another object of the present invention is to provide high white sodium aluminum silicate prepared by the above method.

[0008] Another object of the present invention is to provide an application of the above-mentioned high white sodium aluminum silicate, which can replace 30-50wt% of titanium dioxide in paints, latex paints, etc., to improve the dispersibility, stability, hiding power and tinting power of the pigment.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] The present invention provides a method for preparing high white sodium aluminum silicate, comprising the following steps:

[0011] 1) Add aluminum salt solution and water as base liquid to the reactor, control the pH value to 4-6, start stirring, and heat to 45-65°C;

[0012] 2) adding aluminum salt solution and sodium silicate solution into the reaction kettle for reaction, controlling the pH value to be 4-6, the reaction temperature to be 45-65° C., and the reaction time to be 10-30 min; after the reaction is completed, stirring for 40-60 min;

[0013] 3) Continue to add sodium silicate solution into the reactor until the pH value is adjusted to 8-10;

[0014] 4) Continue to add sodium silicate solution and aluminum salt solution into the reactor, control the pH value of the reaction process to 8-10, the reaction time to 50-70 minutes, and age for 10-30 minutes after the co-flow ends;

[0015] 5) Add sulfuric acid solution to the reactor, adjust the pH value to 3.5-4.5, add masking agent, and stir for 20-40 minutes;

[0016] 6) The solution obtained in step 5) is subjected to solid-liquid separation, washing, pulping and drying to obtain a high white sodium aluminum silicate product.

[0017] Preferably, the aluminum salt is at least one of aluminum chloride, aluminum sulfate and aluminum nitrate.

[0018] Preferably, the concentration of the aluminum salt solution is 10-30wt%.

[0019] Preferably, the concentration of the sodium silicate is 2.0-3.0 mol / L.

[0020] Preferably, the masking agent is at least one of oxalic acid, citric acid, tartaric acid and pyrophosphoric acid.

[0021] Preferably, the amount of the masking agent added is 3-8‰ of the total mass of the sodium aluminum silicate in the reaction kettle in step 5).

[0022] Preferably, in step 2), the aluminum salt solution and the sodium silicate solution are added to the reaction kettle to react, specifically:

[0023] Aluminum salt solution and sodium silicate solution are continuously added dropwise into the reaction kettle to react, and the amount of sodium silicate added is 10-20% of the total volume of the sodium silicate added in step 1) to step 5).

[0024] Preferably, in step 4), the sodium silicate solution and the aluminum salt solution are continuously added to the reactor, and the volume is:

[0025] The aluminum salt solution and the sodium silicate solution are continuously added dropwise into the reaction kettle to react, wherein the dropping speed of the sodium silicate solution in step 4) is 1-2 times the dropping speed of the sodium silicate solution in step 2).

[0026] The invention also provides high white sodium aluminum silicate, which is prepared by the preparation method of the high white sodium aluminum silicate.

[0027] The invention also provides application of the high white sodium aluminum silicate in paint and latex paint.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] (1) The preparation method of high white sodium aluminum silicate of the present invention, step 1) and step 2) control the pH value of the reaction process to 4-6, which can reduce the intensity of the reaction process under weak acidic conditions, improve the uniformity of the nucleation process, and make the formed sodium aluminum silicate micronucleus in a stable state. In the subsequent growth process, it can grow more evenly on the surface of the micronucleus, thereby improving the uniformity and structure of the product; step 3) and step 4) adjust the reaction pH value to 8-10, and under alkaline conditions, sodium aluminum silicate grows rapidly on the surface of the micronucleus to achieve a precipitation reaction; by controlling the reaction by segmented pH value, the particle size of the product can be significantly reduced, the oil absorption value of the product can be increased, and the dispersibility and thickening effect of the product can be improved.

[0030] (2) The preparation method of high white sodium aluminum silicate of the present invention can remove colored ions of the reaction materials by adding a masking agent, thereby improving the purity, whiteness and dispersibility of the product.

[0031] (3) The preparation method of high white sodium aluminum silicate of the present invention uses all raw materials that are common chemical products, has simple reaction equipment and a simple reaction process, and can achieve large-scale production.

[0032] (4) The high white sodium aluminum silicate prepared by the present invention can replace 30-50wt% of titanium dioxide in paints, latex paints, etc., to improve the dispersibility, stability, hiding power and tinting power of the pigment. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] The present invention provides the following technical solution: a method for preparing high white sodium aluminum silicate, comprising the following steps:

[0036] (1) Add 5.8 L of water and aluminum sulfate solution in a total volume to a 10 L reactor, wherein the concentration of the aluminum sulfate solution is 15 wt %. Then, start the stirring system of the reactor to mix the water and the aluminum sulfate solution evenly, control the pH value of the liquid at 5.5, and heat the liquid in the reactor to 60° C.;

[0037] (2) continuously adding a 15 wt% aluminum sulfate solution and a 2.4 mol / L sodium silicate solution into the reactor for reaction, the flow rate of the sodium silicate solution is 0.016 L / min, the pH value in the reactor is controlled to be 5.5 during the reaction process, the reaction time is 10 min, and after the addition of the reaction materials is completed, the reaction is continued with stirring for 40 min;

[0038] (3) Add 2.4 mol / L sodium silicate solution into the reactor until the pH value of the solution reaches 9.5, then stop;

[0039] (4) Add 15 wt% aluminum sulfate solution and 2.4 mol / L sodium silicate solution into the reactor for reaction. The flow rate of the sodium silicate solution is 0.022 L / min. Adjust the pH value of the solution to 9.5. React for 65 min and age for 20 min.

[0040] (5) Continuously add 10 wt% sulfuric acid to the reactor until the pH value reaches 4, add oxalic acid at a concentration of 5‰ of the total mass of sodium aluminum silicate in the reactor, and stir for 20 min;

[0041] (6) The solution obtained in step (5) is subjected to solid-liquid separation, deionized water washing, pulping and drying to obtain a high white sodium aluminosilicate product.

[0042] Example 2

[0043] The present invention provides the following technical solution: a method for preparing high white sodium aluminum silicate, comprising the following steps:

[0044] (1) Add 6.1 L of water and aluminum chloride solution in a total volume to a 10 L reactor, wherein the concentration of the aluminum chloride solution is 30 wt %, then start the stirring system of the reactor to mix the water and the aluminum chloride solution evenly, control the pH value of the liquid at 4.5, and heat the liquid in the reactor to 46° C.;

[0045] (2) continuously adding aluminum chloride with a concentration of 30 wt% and sodium silicate solution with a concentration of 3.0 mol / L into the reactor for reaction, the flow rate of the sodium silicate solution was 0.015 L / min, the pH value in the reactor was controlled to be 4.5 during the reaction process, the reaction time was 18 min, and after the addition of the reaction materials was completed, the stirring reaction was continued for 60 min;

[0046] (3) Add 3.0 mol / L sodium silicate solution into the reactor until the pH value of the solution reaches 8.5, then stop;

[0047] (4) Add 30 wt% aluminum chloride solution and 3.0 mol / L sodium silicate solution into the reactor for reaction. The flow rate of the sodium silicate solution is 0.020 L / min. Adjust the pH value of the solution to 8.5. React for 55 min and age for 15 min.

[0048] (5) Continuously add 30 wt% sulfuric acid to the reactor until the pH value reaches 4.5, add 7‰ citric acid based on the total mass of sodium aluminum silicate in the reactor, and stir for 40 min;

[0049] (6) The solution obtained in step (5) is subjected to solid-liquid separation, deionized water washing, pulping and drying to obtain a high white sodium aluminosilicate product.

[0050] Example 3

[0051] The present invention provides the following technical solution: a method for preparing high white sodium aluminum silicate, comprising the following steps:

[0052] (1) Add 6.0 L of water and a mixed solution of aluminum sulfate and aluminum chloride into a 10 L reactor, wherein the concentration of the mixed aluminum salt is 11 wt %. Then start the stirring system of the reactor to mix the solution evenly, control the pH value of the liquid at 6.0, and heat the liquid in the reactor to 65° C.;

[0053] (2) Adding a mixed aluminum salt having a concentration of 11 wt% and a sodium silicate solution having a concentration of 2.0 mol / L into the reactor continuously for reaction, the flow rate of the sodium silicate solution was 0.009 L / min, the pH value in the reactor was controlled to be 6.0 during the reaction process, the reaction time was 25 min, and after the addition of the reaction materials was completed, the reaction was continued with stirring for 55 min;

[0054] (3) Add 2.0 mol / L sodium silicate solution into the reactor until the pH value of the solution reaches 9.0, then stop;

[0055] (4) Adding a mixed aluminum salt with a concentration of 11 wt% and a sodium silicate solution with a concentration of 2.0 mol / L into the reactor for reaction, the flow rate of the sodium silicate solution was 0.017 L / min, the pH value of the solution was adjusted to 9.0, the reaction was carried out for 70 min, and the aging was carried out for 26 min;

[0056] (5) Continuously add 98 wt% sulfuric acid to the reactor until the pH value reaches 3.5, add 3‰ pyrophosphoric acid based on the total mass of sodium aluminum silicate in the reactor, and stir for 30 min;

[0057] (6) The solution obtained in step (5) is subjected to solid-liquid separation, deionized water washing, pulping and drying to obtain a high white sodium aluminosilicate product.

[0058] Comparative Example 1

[0059] (1) Add 5.8 L of water and aluminum sulfate solution in a total volume to a 10 L reactor, wherein the concentration of the aluminum sulfate solution is 15 wt %. Then, start the stirring system of the reactor to mix the water and the aluminum sulfate solution evenly, control the pH value of the liquid at 5.5, and heat the liquid in the reactor to 60° C.;

[0060] (2) continuously adding 15 wt% aluminum sulfate and 2.4 mol / L sodium silicate solution into the reactor for reaction, the flow rate of the sodium silicate solution was 0.016 L / min, the pH value in the reactor was controlled to be 5.5 during the reaction process, the reaction time was 10 min, and after the addition of the reaction materials was completed, the reaction was continued with stirring for 40 min;

[0061] (3) Add 2.4 mol / L sodium silicate solution into the reactor until the pH value of the solution reaches 9.5, then stop;

[0062] (4) Add 15 wt% aluminum sulfate solution and 2.4 mol / L sodium silicate solution into the reactor for reaction. The flow rate of the sodium silicate solution is 0.022 L / min. Adjust the pH value of the solution to 9.5. React for 65 min and age for 20 min.

[0063] (5) Continuously add 10 wt% sulfuric acid into the reactor until the pH value reaches 4;

[0064] (6) The solution obtained in step (5) is subjected to solid-liquid separation, deionized water washing, pulping and drying to obtain a sodium aluminosilicate product.

[0065] Comparative Example 2

[0066] (1) Add 5.8 L of water and aluminum sulfate solution in a total volume to a 10 L reactor, add a sodium silicate solution with a concentration of 2.4 mol / L to a pH value of 9.5, then start the stirring system of the reactor to mix the solution evenly, and heat the liquid in the reactor to 60° C.;

[0067] (2) 15 wt% aluminum sulfate and 2.4 mol / L sodium silicate solution were continuously added into the reactor for reaction. The flow rate of the sodium silicate solution was 0.016 L / min. The pH value in the reactor was controlled to be 9.5 during the reaction process. The reaction time was 10 min. After the addition of the reaction materials was completed, the reaction was continued with stirring for 40 min.

[0068] (3) Adding 15 wt% aluminum sulfate solution and 2.4 mol / L sodium silicate solution into the reactor for reaction, the flow rate of the sodium silicate solution is 0.022 L / min, adjusting the pH value of the solution to 9.5, reacting for 65 min, and aging for 20 min;

[0069] (4) Continuously add 10 wt% sulfuric acid to the reactor until the pH value is 4, add oxalic acid at 5‰ of the total mass of sodium aluminum silicate in the reactor, and stir for 20 min;

[0070] (5) The solution obtained in step (4) is subjected to solid-liquid separation, deionized water washing, pulping and drying to obtain a high white sodium aluminosilicate product.

[0071] The test results of the sodium aluminosilicate obtained in Examples 1-3 and Comparative Examples 1 and 2 are as follows:

[0072] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Whiteness 98.5 98.1 98.3 94.5 97.8 Iron content 96 112 89 176 98 Particle size 6.27 6.75 5.93 6.41 10.84 Oil absorption value 2.15 2.06 2.23 2.10 1.45

[0073] As can be seen from the above table, the whiteness of the product can be significantly improved and the iron content can be reduced by using a masking agent; the particle size of the product can be significantly reduced and the oil absorption value of the product can be increased by controlling the reaction by segmented pH value, thereby improving the dispersibility and thickening effect of the product.

[0074] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing high white sodium aluminum silicate, characterized in that: The following steps are involved: 1) Add aluminum salt solution and water as base liquid to the reactor, control the pH value to 4-6, start stirring, and heat to 45-65°C; 2) adding aluminum salt solution and sodium silicate solution into the reaction kettle for reaction, controlling the pH value to be 4-6, the reaction temperature to be 45-65°C, and the reaction time to be 10-30min; after the reaction is completed, stirring for 40-60min; 3) Continue to add sodium silicate solution into the reactor until the pH value is adjusted to 8-10; 4) Continue to add sodium silicate solution and aluminum salt solution into the reactor, control the pH value of the reaction process to 8-10, the reaction time to 50-70 minutes, and age for 10-30 minutes after the co-flow ends; 5) Add sulfuric acid solution to the reactor, adjust the pH value to 3.5-4.5, add masking agent, and stir for 20-40 minutes; 6) The solution obtained in step 5) is subjected to solid-liquid separation, washing, pulping and drying to obtain a high white sodium aluminum silicate product.

2. The method for preparing high white sodium aluminum silicate according to claim 1, characterized in that: The aluminum salt is at least one of aluminum chloride, aluminum sulfate and aluminum nitrate.

3. The method for preparing high white sodium aluminum silicate according to claim 1 or 2, characterized in that: The concentration of the aluminum salt solution is 10-30 wt %.

4. The method for preparing high white sodium aluminum silicate according to claim 1, characterized in that: The concentration of the sodium silicate is 2.0-3.0 mol / L.

5. The method for preparing high white sodium aluminum silicate according to claim 1, characterized in that: The masking agent is at least one of oxalic acid, citric acid, tartaric acid and pyrophosphoric acid.

6. The method for preparing high white sodium aluminum silicate according to claim 1 or 3, characterized in that: The amount of the masking agent added is 3-8‰ of the total mass of the sodium aluminum silicate in the reaction kettle in step 5).

7. The method for preparing high white sodium aluminum silicate according to claim 1, characterized in that: Step 2) adding aluminum salt solution and sodium silicate solution into the reaction kettle to react, specifically: Aluminum salt solution and sodium silicate solution are continuously added dropwise into the reaction kettle to react, and the amount of sodium silicate added is 10-20% of the total volume of the sodium silicate added in step 1) to step 5).

8. The method for preparing high white sodium aluminum silicate according to claim 1, characterized in that: Step 4) continues to add sodium silicate solution and aluminum salt solution into the reactor, the volume is: The aluminum salt solution and the sodium silicate solution are continuously added dropwise into the reaction kettle to react, wherein the dropping speed of the sodium silicate solution in step 4) is 1-2 times the dropping speed of the sodium silicate solution in step 2).

9. A high white sodium aluminum silicate, characterized in that: The high white sodium aluminum silicate is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the high white sodium aluminum silicate according to claim 9 in paints and latex paints.