阅读说明：本技术 一种超细疏水二氧化硅及其制备方法 (Superfine hydrophobic silicon dioxide and preparation method thereof ) 是由 王宪伟 郑松玲 庹文喜 王义品 蒋建华 于 2020-06-22 设计创作，主要内容包括：本发明属于二氧化硅技术领域,具体涉及一种超细疏水二氧化硅及其制备方法。本发明采用硅酸钠溶液和硫酸溶液在70-80℃下反应制得二氧化硅物料,经过洗涤干燥后,二氧化硅在气流磨粉机中同步进行超细粉碎和改性,制得超细疏水二氧化硅。本发明提供的超细疏水二氧化硅的外观及粒径均一,疏水效果好,透明度高。本发明提供的超细疏水二氧化硅的制备方法简单易操作,安全环保性好,能够实现连续性生产,生产成本低。(The invention belongs to the technical field of silicon dioxide, and particularly relates to superfine hydrophobic silicon dioxide and a preparation method thereof. The invention adopts sodium silicate solution and sulfuric acid solution to react at 70-80 ℃ to prepare silicon dioxide material, and after washing and drying, the silicon dioxide is synchronously subjected to superfine grinding and modification in an airflow mill to prepare the superfine hydrophobic silicon dioxide. The superfine hydrophobic silicon dioxide provided by the invention has the advantages of uniform appearance and particle size, good hydrophobic effect and high transparency. The preparation method of the superfine hydrophobic silica provided by the invention is simple and easy to operate, is safe and environment-friendly, can realize continuous production, and is low in production cost.)

1. The preparation method of the superfine hydrophobic silica is characterized by comprising the following steps:

s1, adding a sodium silicate solution with the molar concentration of 0.45-0.65mol/L into a reaction tank, heating to 70-80 ℃ by using steam, starting a stirring device, dripping a dilute sulfuric acid solution with the molar concentration of 1.0-1.5mol/L under the condition of stirring frequency of 30-40Hz, and controlling the pH value of a reaction end point to be 3.5-6.0 to prepare a mixed solution A;

s2, performing filter pressing washing and flash evaporation drying on the mixed liquid A prepared in the step S1, and pumping the mixed liquid A into a buffer tank to prepare a dry material;

s3, opening the airflow flour mill, controlling the speed of the grading wheel to 1400-1600rpm, opening the high-temperature air compressor, and pumping high-temperature air;

and S4, spraying the dry material prepared in the step S2 and the silane coupling agent into an airflow mill, and carrying out physical crushing through high-temperature high-pressure gas for 30min to obtain the silane coupling agent.

2. The method for preparing ultra-fine hydrophobic silica according to claim 1, wherein the sodium silicate solution is added in an amount of 10-15m in the step S1³The dropping speed of the dilute sulfuric acid solution is 2-4m³/h。

3. The method as claimed in claim 1, wherein the pressure filtration process in step S2 is performed under a pressure of 1.6-2.0Mpa for 12-16min, the washing time is 80-160min, and the washing conductivity is 2000-; the inlet temperature of the flash drying is 350-550 ℃, and the outlet temperature is 100-130 ℃.

4. The method as claimed in claim 1, wherein the temperature of the high temperature air in the step S3 is 200-250 ℃.

5. The method for preparing ultra-fine hydrophobic silica according to claim 1, wherein the feeding speed of the dry material in the step S4 is 2-3 t/h.

6. The method for preparing ultra-fine hydrophobic silica as claimed in claim 1, wherein the percentage concentration of the silane coupling agent solution in the step S4 is 0.5-10%; the feeding speed of the silane coupling agent is 0.2-0.3 t/h.

7. The method of claim 1, wherein the jet mill of step S3 is connected to a high temperature air compressor, and the silane coupling agent is connected to the injector liquid pipe.

8. An ultra-fine hydrophobic silica prepared by the method for preparing an ultra-fine hydrophobic silica according to any one of claims 1 to 7.

Technical Field

The invention belongs to the technical field of silicon dioxide, and particularly relates to superfine hydrophobic silicon dioxide and a preparation method thereof.

Background

Hydrophobic materials generally refer to materials having a contact angle of water at a static surface of greater than 90 °. Due to good non-wettability to water, the hydrophobic material generally has excellent self-cleaning, pollution resistance, corrosion resistance and other properties, and has wide application prospects in daily life and many industrial fields.

China is a large country for paint production and consumption, but the current domestic paint generally has the defects in performance, such as poor suspension stability, poor thixotropy, poor weather resistance, poor scrub resistance and the like, so that a large amount of high-quality paint needs to be imported every year, and the paint cost is high. After the super-hydrophobic silicon dioxide is applied to the coating, the defects of the conventional product can be overcome, the performance indexes of the coating are greatly improved except that the contrast ratio is unchanged, for example, the washing resistance of the exterior wall coating is improved from thousands of times to ten thousands of times, the time for artificially accelerating weather aging and artificial radiation exposure aging is improved from 250 hours to 600 hours, in addition, the bonding strength of a coating and a wall body is greatly improved, the hardness of the coating is obviously improved, and the surface self-cleaning capability is also improved.

Application publication No. CN104876230A discloses a method for preparing monodisperse ordered hydrophobic silica nanoparticles, which comprises the following steps: firstly, a mixed solution prepared from a surfactant, a prepolymer, water and ethanol is placed in a beaker and stirred for 6 hours below 30 ℃. The mixed solution was poured into a flask, and a certain amount of benzene was added to form a microemulsion, which was stirred at 69 ℃ for 1 hour. The temperature was then adjusted to 105 ℃ until water and ethanol were completely distilled off. And drying the residual solution to obtain a powder sample, adding the mixed washing solution, carrying out high-speed centrifugation, and drying the precipitate below the centrifugal tube at 60 ℃. And collecting the dried product to obtain the monodisperse nano-pore hydrophobic silicon dioxide with uniform size. The hydrophobic silicon dioxide prepared by the preparation method has the advantages of complex preparation method, more reagent types and higher production cost.

In conclusion, the prior art has various technical problems of complex preparation method, various reagent types, high production cost, poor safety and environmental protection performance and the like.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide the ultrafine hydrophobic silica and the preparation method thereof. The preparation method of the superfine hydrophobic silicon dioxide simplifies the preparation process of the hydrophobic silicon dioxide, reduces the production cost, improves the production yield, and is safe and environment-friendly.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of ultrafine hydrophobic silica specifically comprises the following steps:

s1, adding a sodium silicate solution with the molar concentration of 0.45-0.65mol/L into a reaction tank, heating to 70-80 ℃ by using steam, starting a stirring device, dripping a dilute sulfuric acid solution with the molar concentration of 1.0-1.5mol/L under the condition of stirring frequency of 30-40Hz, and controlling the pH value of a reaction end point to be 3.5-6.0 to prepare a mixed solution A;

s2, performing filter pressing washing and flash evaporation drying on the mixed liquid A prepared in the step S1, and pumping the mixed liquid A into a buffer tank to prepare a dry material;

s3, opening the airflow flour mill, controlling the speed of the grading wheel to 1400-1600rpm, opening the high-temperature air compressor, and pumping high-temperature air;

and S4, spraying the dry material prepared in the step S2 and the silane coupling agent into an airflow mill, and carrying out physical crushing through high-temperature high-pressure gas for 30min to obtain the silane coupling agent.

Further, the adding amount of the sodium silicate solution in the step S1 is 10-15m³The dropping speed of the dilute sulfuric acid solution is 2-4m³/h。

Further, in the step S2, feeding for 12-16min under the condition that the pressure in the pressure filtration process is kept at 1.6-2.0Mpa, the washing time is 80-160min, and the washing conductivity is 2000-; the inlet temperature of the flash drying is 350-550 ℃, and the outlet temperature is 100-130 ℃.

Further, the temperature of the high temperature air in the step S3 is 200-250 ℃.

Further, the feeding speed of the dry material in the step S4 is 2-3 t/h.

Further, the percentage concentration of the silane coupling agent solution in the step S4 is 0.5-10%; the feeding speed of the silane coupling agent is 0.2-0.3 t/h.

Further, the airflow mill in the step S3 is connected to a high-temperature air compressor, and the liquid pipe of the ejector is connected to a silane coupling agent.

The invention also provides the superfine hydrophobic silicon dioxide prepared by the preparation method.

The invention adopts sodium silicate solution and sulfuric acid solution to react at 70-80 ℃ to prepare silicon dioxide material, and after washing and drying, the silicon dioxide is synchronously subjected to superfine grinding and modification in an airflow mill to prepare the superfine hydrophobic silicon dioxide. The invention controls the reaction end point of the sodium silicate solution and the sulfuric acid solution, so that the generated silicon dioxide particles are loose and porous and have higher transparency.

After the silicon dioxide particles are fully contacted with the silane coupling agent in the airflow mill, the silane coupling agent can be adsorbed on the surface of the silicon dioxide particles, so that a plurality of small bulges are formed on the surface of the silicon dioxide particles, a small air chamber with one is formed in the middle of each bulge, a special micro-nano structure is formed, after the superfine hydrophobic silicon dioxide is added into the coating, water drops are large in size and cannot enter the small air chambers, and the hydrophobic property of the superfine hydrophobic silicon dioxide is improved.

In addition, the superfine hydrophobic silica with uniform appearance, particle size and weight can be separated by a higher classifying wheel speed in the airflow mill, so that the worthy superfine hydrophobic silica has uniform particle size and better performance. The raw materials in the preparation process of the superfine hydrophobic silica only comprise a sodium silicate solution, a sulfuric acid solution and a silane coupling agent, so that the types of the hydrophobic silica reaction raw materials in the prior art are greatly reduced, the production cost is greatly reduced, and the sodium silicate solution, the dilute sulfuric acid solution and the silane coupling agent are harmless to human bodies and environment-friendly, so that the safety and environmental friendliness are greatly improved.

Compared with the prior art, the superfine hydrophobic silicon dioxide and the preparation method thereof provided by the invention have the following advantages:

(1) the hydrophobic silicon dioxide prepared by the invention has uniform particle size, good hydrophobic effect and high transparency;

(2) the preparation method of the hydrophobic silicon dioxide provided by the invention is simple, the conditions are controllable, and the industrial production is easy to realize;

(3) the preparation method of the hydrophobic silicon dioxide provided by the invention has the advantages of less reaction raw materials and good environmental protection performance, reduces the production cost of the hydrophobic silicon dioxide, and improves the technical problem of poor safety and environmental protection.

Detailed Description

The present invention will be further described below by way of specific embodiments, but the present invention is not limited to only the following examples. Various modifications can be made by those skilled in the art based on the basic idea of the invention, but it is within the scope of the invention as long as it does not depart from the basic idea of the invention.

The air current milling machine in this embodiment is connected with the high-temperature air compressor, and the liquid pipe of the ejector is connected with the silane coupling agent.