High-stability silica suspending agent and method for preparing the same

Abstract

The application discloses a high-stability silica suspension agent and a preparation method thereof, and belongs to the technical field of suspension agent preparation. With 1L of finished product suspension agent as a benchmark, the specific gravity of the finished product is 1.16g / mL, the total mass is 1160g, and the weight ratio content of silica is 17.3%. The component dosages are as follows: 200g of precipitated hydrophilic nano-silica powder, 46.4g of anionic polyacrylic acid sodium dispersant, 46.4g of anionic emulsifier, 232g of antifreeze, 1.74g of xanthan gum anti-settling agent, 3.48g of organic silicon defoaming agent and 4.64g of 1,2-benzisothiazolinone aqueous solution. The application removes non-ionic surfactants and inorganic powder special wetting agents in the formula system, thereby avoiding the negative influence caused by the synergistic use of the two types of auxiliaries, effectively solving the problems of large foam amount, high defoaming difficulty in the production and use process of traditional products, avoiding the occurrence of adverse phenomena such as system viscosity disorder and large pH value fluctuation range, and greatly improving the stability of the overall physicochemical performance of the silica suspension agent.

Description

Technical Field

[0001] This invention relates to the field of suspending agent preparation technology, and more specifically, to a highly stable silica suspending agent and its preparation method. Background Technology

[0002] Silica suspensions, leveraging the excellent chemical stability, wear resistance, and filling properties of nano-silica, are now widely used in numerous industries such as coatings, daily chemical products, industrial additives, and fine chemicals. In existing technologies, to improve the wetting effect of hydrophobic / hydrophilic inorganic silica powders in aqueous media and enhance the initial dispersion efficiency, the industry commonly uses nonionic surfactants and inorganic powder-specific wetting agents in combination with conventional additives such as dispersants, thickeners, and preservatives when preparing silica suspensions. This formulation method is currently the most prevalent mainstream technology in the market.

[0003] Traditional formulation systems have many unavoidable technical defects: First, when nonionic surfactants and inorganic powder-specific wetting agents are added together to an aqueous system, they can easily cause violent foaming, which not only increases the difficulty of the defoaming process in production, but also causes the overall viscosity of the suspension to become out of control and the pH value to decrease. Second, these two types of additives can destroy the colloidal stability of the suspension system, leading to frequent problems such as stratification and silica powder sedimentation during long-term storage of the finished product. They can also provide conditions for microbial growth, making the product prone to mold and deterioration, severely shortening the product's service life, and failing to meet the current market's high standards for the use of silica suspensions with high stability and long shelf life.

[0004] Based on this, the present invention designs a highly stable silica suspending agent and its preparation method to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a highly stable silica suspending agent and its preparation method, so as to solve the problems mentioned in the background art.

[0006] A highly stable silica suspending agent, based on 1L of finished suspending agent, has a specific gravity of 1.16g / mL, a total mass of 1160g, and a silica weight content of 17.3%. The amounts of each component are as follows: 200g of precipitated hydrophilic nano silica powder, 46.4g of anionic sodium polyacrylate dispersant, 46.4g of anionic emulsifier, 232g of antifreeze, 1.74g of xanthan gum antisettling agent, 3.48g of organosilicon defoamer, 4.64g of 1,2-benzisothiazolinone aqueous solution, 4.64g of sodium benzoate, organic amine pH adjuster, anhydrous sodium gluconate, and the balance being deionized water. The suspending agent has a pH of 7.1 at 25℃, a foam volume ≤10mL, and a dynamic viscosity of 50~200mPa・s. No nonionic surfactants or inorganic powder-specific wetting agents are added.

[0007] Preferably, the anhydrous sodium gluconate powder has a fineness of ≥200 mesh.

[0008] Preferably, the average particle size D50 of the precipitation-method hydrophilic nano silica powder is 0.1 μm to 0.3 μm, and the mass percentage of silica is ≥99%.

[0009] Preferably, the anionic sodium polyacrylate dispersant has a number average molecular weight of 4000-8000 and a solid content of 40%±2%.

[0010] Preferably, the effective substance content of the 1,2-benzisothiazolinone aqueous solution is 10%.

[0011] Preferably, the organic amine pH adjuster is 2-amino-2-methyl-1-propanol AMP-95.

[0012] Preferably, the anionic emulsifier is an aqueous anionic emulsifier, and no nonionic emulsifier is used.

[0013] Preferably, the antifreeze agent is ethylene glycol or propylene glycol.

[0014] A method for preparing a highly stable silica suspending agent includes the following steps: S1. Preparation of base solution: Add the prescribed amount of deionized water and antifreeze to a sealed stirred reactor. Under low-speed stirring at 300 rpm to 500 rpm, add the organic amine pH adjuster, 1,2-benzisothiazolinone aqueous solution, sodium benzoate, anhydrous sodium gluconate, and anionic emulsifier in sequence. Continue stirring at a constant temperature for 5 min to 10 min until all the additives are completely dissolved to obtain a clear and homogeneous aqueous base solution. S2. High-speed dispersion of powder: Add the formulated amount of anionic sodium polyacrylate dispersant to the prepared base liquid, stir at a uniform speed for 10 minutes, then increase the stirring speed to 1000 rpm to 2000 rpm for high-speed shear dispersion, add silica powder in 3 to 5 batches in equal amounts, with an interval of 3 to 5 minutes between two consecutive additions, and continue high-speed shear dispersion for 30 to 60 minutes after all powder has been added; S3. Thickening and preparation of the system: Reduce the stirring speed to 300 rpm to 500 rpm, add the xanthan gum anti-settling agent of the formula, and stir continuously at a constant temperature for 20 min to 30 min; S4. Post-processing filtration and discharge: Add the formula amount of organosilicon defoamer and stir to mix evenly. Let it stand at room temperature in a sealed environment for 24 hours. Maintain low-speed stirring at 50 rpm throughout the aging process. Finally, filter and remove impurities using a 200-300 mesh standard filter screen to obtain the finished suspension.

[0015] Compared with the prior art, the advantages of this invention are:

[0016] 1. This invention avoids the negative impact of the synergistic use of two types of additives by removing nonionic surfactants and inorganic powder-specific wetting agents from the formulation system. It effectively solves the problems of large foam volume and high defoaming difficulty in the production and use of traditional products. At the same time, it avoids adverse phenomena such as system viscosity disorder and large pH fluctuation, and greatly improves the stability of the overall physicochemical properties of silica suspension.

[0017] 2. This invention, by compounding anhydrous sodium gluconate as a functional additive in the formulation, achieves a good synergistic effect with anionic sodium polyacrylate dispersant and xanthan gum anti-settling agent, further optimizing the dispersion state of hydrophilic nano-silica powder in the aqueous phase by precipitation method, effectively inhibiting the agglomeration and sedimentation of powder particles, and significantly enhancing the anti-settling ability of high solid content silica suspension system. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of a method for preparing a highly stable silica suspending agent proposed in this invention. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Prepare 1L of suspension, with a finished product specific gravity of 1.16g / mL and a total mass of 1160g; do not add nonionic surfactants, inorganic powder-specific wetting agents, or nonionic emulsifiers.

[0021] Example 1

[0022] Formula composition (1L finished product, total mass 1160g): 200g precipitated hydrophilic nano-silica, 46.4g anionic sodium polyacrylate dispersant, 46.4g aqueous anionic emulsifier, 232g ethylene glycol antifreeze, 1.74g xanthan gum antisettling agent, 3.48g silicone defoamer, 4.64g 1,2-benzisothiazolinone aqueous solution, 4.64g sodium benzoate, and appropriate amount of 2-amino 2-Methyl-1-propanol AMP-95, an appropriate amount of anhydrous sodium gluconate, and deionized water to make up to 1L (total mass 1160g); wherein the precipitated hydrophilic nano silica has a D50 of 0.1μm and a purity of ≥99%, the anionic sodium polyacrylate dispersant has a number average molecular weight of 4000 and a solid content of 40%±2%, the 1,2-benzisothiazolinone aqueous solution has an effective content of 10%, and the anhydrous sodium gluconate has a fineness of 220 mesh.

[0023] Preparation method

[0024] S1. Preparation of base solution: Add the prescribed amount of deionized water and ethylene glycol antifreeze to a sealed stirred reactor, stir at a low speed of 300 rpm, and then add AMP-95, 1,2-benzisothiazolinone aqueous solution, sodium benzoate, anhydrous sodium gluconate, and aqueous anionic emulsifier in sequence. Stir at a constant temperature for 5 min to obtain a clear and homogeneous aqueous base solution.

[0025] S2. High-speed dispersion of powder: Add anionic sodium polyacrylate dispersant to the base liquid and stir at a constant speed for 10 minutes; increase the speed to 1000 rpm for high-speed shearing; feed silica powder in 3 batches in equal amounts, with an interval of 3 minutes between adjacent feedings; after all feedings are completed, continue high-speed shearing dispersion for 30 minutes.

[0026] S3. Thickening and preparation of the system: Reduce the speed to 300 rpm, add xanthan gum anti-settling agent, and stir at a constant temperature for 20 minutes.

[0027] S4. Post-processing filtration and discharge: Add organosilicon defoamer and stir to mix well; age at room temperature in a sealed environment for 24 hours, maintaining a low stirring speed of 50 rpm throughout the aging process; finally, filter and remove impurities using a 200-mesh standard filter screen to obtain the finished suspension.

[0028] Finished product performance testing (25℃): Specific gravity: 1.16 g / mL; pH value: 7.1; Silica weight percentage: 17.3%; Foam volume: 8 mL; Dynamic viscosity: 50 mPa·s; System state: The system is uniform and stable, with no stratification, no sedimentation, no residual bubbles, excellent low-temperature antifreeze performance, and good anti-corrosion effect.

[0029] Example 2

[0030] Formula composition (1L finished product, total mass 1160g): 200g precipitated hydrophilic nano-silica, 46.4g anionic sodium polyacrylate dispersant, 46.4g aqueous anionic emulsifier, 232g propylene glycol antifreeze, 1.74g xanthan gum antisettling agent, 3.48g silicone defoamer, 4.64g 1,2-benzisothiazolinone aqueous solution, 4.64g sodium benzoate, and appropriate amount of 2-amino 2-Methyl-1-propanol AMP-95, an appropriate amount of anhydrous sodium gluconate, and deionized water to make up to 1L (total mass 1160g); wherein the precipitated hydrophilic nano silica has a D50 of 0.2μm and a purity of ≥99%, the anionic sodium polyacrylate dispersant has a number average molecular weight of 6000 and a solid content of 40%±2%, the 1,2-benzisothiazolinone aqueous solution has an effective content of 10%, and the anhydrous sodium gluconate has a fineness of 220 mesh.

[0031] Preparation method

[0032] S1. Preparation of base solution: Add the prescribed amount of deionized water and propylene glycol antifreeze to a sealed stirred reactor, stir at low speed of 400 rpm, and then add AMP-95, 1,2-benzisothiazolinone aqueous solution, sodium benzoate, anhydrous sodium gluconate, and aqueous anionic emulsifier in sequence. Stir at constant temperature for 7.5 min to obtain a clear and homogeneous aqueous base solution.

[0033] S2. High-speed dispersion of powder: Add anionic sodium polyacrylate dispersant to the base liquid and stir at a constant speed for 10 minutes; increase the speed to 1500 rpm for high-speed shearing; feed silica powder in 4 batches in equal amounts, with an interval of 4 minutes between adjacent feedings; after all feedings are completed, continue high-speed shearing dispersion for 45 minutes.

[0034] S3. Thickening and preparation of the system: Reduce the speed to 400 rpm, add xanthan gum anti-settling agent, and stir at a constant temperature for 25 minutes.

[0035] S4. Post-processing filtration and discharge: Add silicone defoamer and stir to mix well; age at room temperature in a sealed environment for 24 hours, maintaining a low stirring speed of 50 rpm throughout the aging process; finally, filter and remove impurities using a 250-mesh standard filter screen to obtain the finished suspension.

[0036] Finished product performance testing (25℃): Specific gravity: 1.16 g / mL; pH value: 7.1; Silica weight percentage: 17.3%; Foam volume: 9 mL; Dynamic viscosity: 125 mPa・s; System status: Good fluidity, no sedimentation or stratification after long-term standing, and meets the standards for anti-foaming, anti-corrosion, and low-temperature antifreeze properties.

[0037] Example 3

[0038] Formula composition (1L finished product, total mass 1160g): 200g precipitated hydrophilic nano-silica, 46.4g anionic sodium polyacrylate dispersant, 46.4g aqueous anionic emulsifier, 232g ethylene glycol antifreeze, 1.74g xanthan gum antisettling agent, 3.48g silicone defoamer, 4.64g 1,2-benzisothiazolinone aqueous solution, 4.64g sodium benzoate, and appropriate amount of 2-amino 2-Methyl-1-propanol AMP-95, an appropriate amount of anhydrous sodium gluconate, and deionized water to make up to 1L (total mass 1160g); wherein the precipitated hydrophilic nano silica has a D50 of 0.3μm and a purity of ≥99%, the anionic sodium polyacrylate dispersant has a number average molecular weight of 8000 and a solid content of 40%±2%, the 1,2-benzisothiazolinone aqueous solution has an effective content of 10%, and the anhydrous sodium gluconate has a fineness of 220 mesh.

[0039] Preparation method

[0040] S1. Preparation of base solution: Add the prescribed amount of deionized water and ethylene glycol antifreeze to a sealed stirred reactor, stir at low speed of 500 rpm, and then add AMP-95, 1,2-benzisothiazolinone aqueous solution, sodium benzoate, anhydrous sodium gluconate, and aqueous anionic emulsifier in sequence. Stir at constant temperature for 10 min to obtain a clear and homogeneous aqueous base solution.

[0041] S2. High-speed dispersion of powder: Add anionic sodium polyacrylate dispersant to the base liquid and stir at a constant speed for 10 minutes; increase the speed to 2000 rpm for high-speed shearing; feed silica powder in 5 batches in equal amounts, with an interval of 5 minutes between adjacent feedings; after all feedings are completed, continue high-speed shearing dispersion for 60 minutes.

[0042] S3. Thickening and preparation of the system: Reduce the speed to 500 rpm, add xanthan gum anti-settling agent, and stir at a constant temperature for 30 minutes.

[0043] S4. Post-processing filtration and discharge: Add organosilicon defoamer and stir to mix evenly; age at room temperature in a sealed environment for 24 hours, maintaining a low stirring speed of 50 rpm throughout the aging process; finally, filter and remove impurities using a 300-mesh standard filter screen to obtain the finished suspension.

[0044] Finished product performance testing (25℃): Specific gravity: 1.16 g / mL; pH value: 7.1; Silica weight percentage: 17.3%; Foam volume: 10 mL; Dynamic viscosity: 200 mPa·s; System characteristics: moderate consistency, no powder agglomeration, thorough defoaming, and excellent storage stability, freeze resistance, and corrosion resistance.

[0045] Comparative Example Comparative Example 1 (without the addition of anhydrous sodium gluconate) Formula composition (1L finished product, total mass 1160g): 200g precipitated hydrophilic nano-silica, 46.4g anionic sodium polyacrylate dispersant, 46.4g aqueous anionic emulsifier, 232g propylene glycol antifreeze, 1.74g xanthan gum antisettling agent, 3.48g silicone defoamer, 4.64g 1,2-benzisothiazolinone aqueous solution, 4.64g sodium benzoate, and appropriate amount of 2-amino-2 1,2-Methyl-1-propanol AMP-95, deionized water to 1L (total mass 1160g); wherein the precipitated hydrophilic nano silica has a D50 of 0.2μm and a purity of ≥99%, the anionic sodium polyacrylate dispersant has a number average molecular weight of 6000 and a solid content of 40%±2%, and the 1,2-benzisothiazolinone aqueous solution has an effective content of 10%. The system does not contain nonionic surfactants, inorganic powder wetting agents, or nonionic emulsifiers.

[0046] Preparation method: The preparation process, stirring speed, heat preservation time, feeding method, aging, and filtration parameters are exactly the same as those in Example 2.

[0047] Finished product results (25℃): Specific gravity: 1.16g / mL, pH value: 7.1, foam volume: 9mL; After the system was left to stand for 12 hours, obvious silica precipitation appeared at the bottom, the suspension stability decreased significantly, and the viscosity of the system fluctuated significantly.

[0048] Comparative Example 2 (with added nonionic surfactant and inorganic powder-specific wetting agent) Formula composition (1L finished product, total mass 1160g): 200g precipitated hydrophilic nano-silica, 46.4g anionic sodium polyacrylate dispersant, 46.4g aqueous anionic emulsifier, 232g propylene glycol antifreeze, 1.74g xanthan gum antisettling agent, 3.48g silicone defoamer, 4.64g 1,2-benzisothiazolinone aqueous solution, 4.64g sodium benzoate, and appropriate amount of 2-amino-2-methyl-1-propanediol. Alcohol AMP-95, appropriate amount of anhydrous sodium gluconate, inorganic powder wetting agent, nonionic surfactant, and deionized water to make up to 1L (total mass 1160g); wherein the precipitated hydrophilic nano silica has a D50 of 0.2μm and a purity of ≥99%, the anionic sodium polyacrylate dispersant has a number average molecular weight of 6000 and a solid content of 40%±2%, the 1,2-benzisothiazolinone aqueous solution has an effective content of 10%, and the anhydrous sodium gluconate has a fineness of 220 mesh.

[0049] Preparation method: The preparation process and all process parameters are the same as in Example 2.

[0050] Finished product performance (25℃): The system produces a large amount of foam with a volume >30mL; viscosity is out of control and pH stability deteriorates; long-term storage is prone to stratification and mold growth, resulting in a serious decline in the overall performance of the product.

[0051] Comparison and summary As can be seen from the above examples and comparative examples, the suspending agent prepared according to the formulation and preparation process of the present invention has advantages such as good powder dispersibility, stable system viscosity and pH value, excellent anti-settling, anti-foaming and anti-corrosion properties, and no stratification during long-term storage. Due to the lack of sodium gluconate, the anti-settling ability of the product in Comparative Example 1 is significantly reduced, the system is prone to precipitation and large viscosity fluctuations. After adding nonionic surfactant and inorganic powder-specific wetting agent in Comparative Example 2, the foaming amount of the system increases dramatically, the viscosity becomes out of control, the pH stability deteriorates, and it is prone to stratification and mold growth during storage, resulting in a significant reduction in the overall performance of the product.

[0052] In summary, the silica suspension prepared by this invention through specific raw material compounding and precise process parameter control exhibits excellent comprehensive performance and has good prospects for industrial application.

[0053] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A highly stable silica suspending agent, characterized in that, Based on 1L of finished suspension, the specific gravity of the finished product is 1.16g / mL, the total mass is 1160g, the silica weight content is 17.3%, and the dosage of each component is as follows: 200g of precipitated hydrophilic nano silica powder, 46.4g of anionic sodium polyacrylate dispersant, 46.4g of anionic emulsifier, 232g of antifreeze, 1.74g of xanthan gum antisettling agent, 3.48g of organosilicon defoamer, 4.64g of 1,2-benzisothiazolinone aqueous solution, 4.64g of sodium benzoate, organic amine pH adjuster, anhydrous sodium gluconate, and the balance is deionized water. The suspension has a pH of 7.1 at 25℃, a foam volume ≤10mL, and a dynamic viscosity of 50~200mPa・s. No nonionic surfactants or inorganic powder-specific wetting agents are added.

2. The highly stable silica suspending agent according to claim 1, characterized in that, The anhydrous sodium gluconate powder has a fineness of ≥200 mesh.

3. The highly stable silica suspending agent according to claim 1, characterized in that, The average particle size D50 of the precipitated hydrophilic nano silica powder is 0.1 μm to 0.3 μm, and the mass percentage of silica is ≥99%.

4. The highly stable silica suspending agent according to claim 1, characterized in that, The anionic sodium polyacrylate dispersant has a number average molecular weight of 4000-8000 and a solid content of 40%±2%.

5. The highly stable silica suspending agent according to claim 1, characterized in that, The effective substance content of the 1,2-benzisothiazolinone aqueous solution is 10%.

6. The highly stable silica suspending agent according to claim 1, characterized in that, The organic amine pH adjuster is 2-amino-2-methyl-1-propanol AMP-95.

7. The highly stable silica suspending agent according to claim 1, characterized in that, The anionic emulsifier is an aqueous anionic emulsifier; no nonionic emulsifier is used.

8. The highly stable silica suspending agent according to claim 1, characterized in that, The antifreeze agent is ethylene glycol or propylene glycol.

9. A method for preparing a highly stable silica suspending agent according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Preparation of base solution: Add the prescribed amount of deionized water and antifreeze to a sealed stirred reactor. Under low-speed stirring at 300 rpm to 500 rpm, add the organic amine pH adjuster, 1,2-benzisothiazolinone aqueous solution, sodium benzoate, anhydrous sodium gluconate, and anionic emulsifier in sequence. Continue stirring at a constant temperature for 5 min to 10 min until all additives are completely dissolved to obtain a clear and homogeneous aqueous base solution. S2. High-speed dispersion of powder: Add the formulated amount of anionic sodium polyacrylate dispersant to the prepared base liquid, stir at a uniform speed for 10 minutes, then increase the stirring speed to 1000 rpm to 2000 rpm for high-speed shear dispersion, add silica powder in 3 to 5 batches in equal amounts, with an interval of 3 to 5 minutes between two consecutive additions, and continue high-speed shear dispersion for 30 to 60 minutes after all powder has been added; S3. Thickening and preparation of the system: Reduce the stirring speed to 300 rpm to 500 rpm, add the xanthan gum anti-settling agent of the formula, and stir continuously at a constant temperature for 20 min to 30 min; S4. Post-processing filtration and discharge: Add the formula amount of organosilicon defoamer and stir to mix evenly. Let it stand at room temperature in a sealed environment for 24 hours. Maintain low-speed stirring at 50 rpm throughout the aging process. Finally, filter and remove impurities using a 200-300 mesh standard filter screen to obtain the finished suspension.

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