阅读说明：本技术 高弹性能硅橡胶用的低比表面积纳米二氧化硅制备方法 (Preparation method of low-specific-surface-area nano silicon dioxide for high-elasticity-energy silicon rubber ) 是由 王承辉 汤晓剑 杨军 马秀娟 于 2018-05-28 设计创作，主要内容包括：本发明涉及硅橡胶材料技术领域,具体涉及高弹性能硅橡胶用的低比表面积纳米二氧化硅制备方法,包括以下步骤：底水升温后加入占底水1-5wt％固体硫酸钠搅拌溶解,再加入占底水体积30-50％的水玻璃溶液得到反应液,分别控制流量为3-6m<Sup>3</Sup>/h和10-15m<Sup>3</Sup>/h加入稀硫酸和水玻璃溶液,持续加入时间为100-135min,再加入酸性硫酸铝溶液调节反应液pH值为3-5得到反应浆料；将反应浆料加水洗涤再干燥粉碎。该制备方法通过水玻璃溶液、硫酸和硫酸铝按一定的配比混合在加热条件下生成纳米氢氧化铝凝胶,与二氧化硅复合形成较大的二次结构聚合体,提高了二氧化硅在硅橡胶中的分散性,从而降低二氧化硅结构的滞后性,有效提高硅橡胶制品的弹性。(The invention relates to the technical field of silicon rubber materials, in particular to a preparation method of low-specific-surface-area nano silicon dioxide for high-elasticity-energy silicon rubber, which comprises the following steps: heating the bottom water, adding solid sodium sulfate 1-5 wt% of the bottom water, stirring to dissolve, adding water glass solution 30-50% of the bottom water volume to obtain reaction solution, and controlling flow rate to 3-6m 3 H and 10-15m 3 Adding dilute sulfuric acid and a water glass solution for 100-; and adding water into the reaction slurry, washing, drying and crushing. According to the preparation method, the water glass solution, the sulfuric acid and the aluminum sulfate are mixed according to a certain proportion to generate the nano aluminum hydroxide gel under the heating condition, and the nano aluminum hydroxide gel is compounded with the silicon dioxide to form a larger secondary structure polymer, so that the dispersibility of the silicon dioxide in the silicon rubber is improved, the hysteresis of the silicon dioxide structure is reduced, and the elasticity of a silicon rubber product is effectively improved.)

1. A preparation method of low specific surface area nano silicon dioxide for high elastic energy silicon rubber is characterized by comprising the following steps:

heating the bottom water, adding solid sodium sulfate 1-5 wt% of the bottom water, stirring to dissolve, and adding the bottom waterStirring water glass solution with water volume of 30-50% to obtain reaction solution, and controlling flow rate to 3-6m³H and 10-15m³Adding dilute sulfuric acid and water glass solution for 100-135min, controlling the pH value of the reaction solution to be 10.0-11.0, and reacting at 3-5m³Adding the acidic aluminum sulfate solution into the reaction liquid at a flow rate of/h to adjust the pH value to 3-5 to obtain reaction slurry;

wherein the concentration of aluminum sulfate in the acidic aluminum sulfate solution is 14.3-38.0 wt%, and the SiO of the water glass solution₂The content of (B) is 15-25 wt%;

and adding water into the reaction slurry, washing, drying and crushing to obtain the low-specific-surface-area nano silicon dioxide for the high-elasticity-energy silicon rubber.

2. The method for preparing the nano-silica with the low specific surface area for the high elastic energy silicone rubber according to claim 1, wherein the method for preparing the acidic aluminum sulfate solution comprises the following steps: adding dilute sulfuric acid solution and solid aluminum sulfate, and stirring to obtain acid aluminum sulfate solution with aluminum sulfate concentration of 14.3-38.0 wt%.

3. The method for preparing the nano-silica with the low specific surface area for the high elastic energy silicone rubber according to claim 1, wherein the method for preparing the water glass solution comprises the following steps: putting solid sodium silicate into a static pressure kettle, introducing steam, pressurizing to 0.6-0.8MPa, adding water to prepare SiO₂A water glass solution in an amount of 15 to 25 wt%.

4. The method for preparing the nano silicon dioxide with the low specific surface area for the high elastic energy silicon rubber according to claim 1, wherein the water glass solution is prepared from solid water glass with the modulus of 3.0-3.6.

5. The method for preparing the nano-silica with the low specific surface area for the high elastic energy silicone rubber according to claim 1, wherein the reaction temperature of the reaction solution is 85-95 ℃.

6. The method for preparing the nano-silica with the low specific surface area for the high elastic energy silicone rubber according to claim 1, is characterized by comprising the following steps:

step 1: at 10m³Adding 3m into enamel reaction kettle³Water, then 3m³Stirring the 30 wt% dilute sulfuric acid, adding 2280kg solid aluminum sulfate, and stirring for 30min to obtain an acidic aluminum sulfate solution;

step 2: selecting food-grade solid water glass with modulus of 3.3, adding into static pressure kettle, adding treated water, introducing steam passing through precision filter, pressurizing to 0.8MPa, maintaining pressure for 2 hr, adding water, and making into SiO₂The water glass solution with the content of 18 wt% is stored for later use;

and step 3: at 60m³10m of the mixture is firstly added into a reaction kettle³Introducing steam into the bottom water, heating to 98 ℃, adding 100kg of solid sodium sulfate, stirring for dissolving, and adding 5m of solid sodium sulfate³Stirring the water glass solution uniformly to obtain a reaction solution, starting the reaction, and respectively controlling the flow rate to be 3m³H and 10m³Adding 23 wt% of dilute sulfuric acid and the water glass solution for 135min, controlling the pH value of the reaction solution to be 11.0, controlling the reaction temperature to be 98 ℃, and performing reaction at the temperature of 2m after the reaction is finished³Adding the acidic aluminum sulfate solution into the reaction solution at a flow rate of/h, adjusting the pH value to 5, and aging for 30min to obtain reaction slurry;

and 4, step 4: adding filtered tap water into the reaction slurry for washing until the conductivity of filtered water is 100 mu S/cm, filtering water to obtain spray slurry, carrying out high-speed rotary atomization on the spray slurry through spray drying equipment, heating and drying by utilizing hot air to prepare powdery silicon dioxide, and crushing the silicon dioxide to a particle size D by using an internal grading type pulverizer₅₀The nano silicon dioxide with low specific surface area for the high elastic energy silicon rubber is prepared with the particle size of 8.0 mu m.

Technical Field

The invention relates to the technical field of silicon rubber materials, in particular to a preparation method of low-specific-surface-area nano silicon dioxide for high-elasticity-energy silicon rubber.

Background

High elasticity is the most valuable property of silicone rubber, and is formed by the movement of molecular chain segments of silicone rubber through conformational changes. Because the interaction between silicone rubber molecules can hinder the movement of molecular chain segments, part of the force acting on the silicone rubber molecules is used for overcoming the viscous resistance between the molecules, and the other part deforms the molecular chains, so that the molecular chains form the viscoelasticity of the silicone rubber. Therefore, the silicon rubber has the characteristics of high elasticity and viscosity.

The compression set is closely related to the sealing properties of the article, and the smaller the compression set, the better the sealing properties of the article. The high-resilience low-compression-deformation product is mainly applied to a sealing product in a wide range, and the high-temperature vulcanized silicone rubber in the prior art cannot meet the special requirements of certain products in the market due to low resilience, such as shaft seal rings, gaskets, seal rings/gaskets/strips, miscellaneous parts joints, automobile connecting and sealing assemblies and the like, so that the elastic property of the silicone rubber needs to be further improved.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: provides a preparation method of silicon dioxide with low specific surface area for silicon rubber, which effectively improves the elasticity of the silicon rubber.

In order to solve the technical problems, the invention adopts the technical scheme that: a preparation method of low specific surface area nano silicon dioxide for high elastic energy silicon rubber comprises the following steps:

heating the bottom water, adding solid sodium sulfate 1-5 wt% of the bottom water, stirring to dissolve, adding water glass solution 30-50% of the bottom water, stirring to obtain reaction solution, and controlling flow rate to 3-6m³H and 10-15m³Adding dilute sulfuric acid and water glass solution to obtain reaction solution, continuously adding for 135min for 100-³Adding the acidic aluminum sulfate solution into the reaction liquid at a flow rate of/h to adjust the pH value to 3-5 to obtain reaction slurry;

wherein the concentration of aluminum sulfate in the acidic aluminum sulfate solution is 14.3-38.0 wt%, and the SiO of the water glass solution₂The content of (B) is 15-25 wt%;

and adding water into the reaction slurry, washing, drying and crushing to obtain the nano silicon dioxide for the high-elasticity silicone rubber.

The invention has the beneficial effects that: the nano aluminum hydroxide gel is generated by mixing the water glass solution, the sulfuric acid and the aluminum sulfate according to a certain proportion under the heating condition and is compounded with the silicon dioxide to form a larger secondary structure polymer, so that the dispersibility of the silicon dioxide in the silicon rubber is improved, the agglomerates of the silicon dioxide in the silicon rubber are easy to open, the hysteresis of the silicon dioxide structure is reduced, the elasticity of a silicon rubber product can be effectively improved, and the nano silicon dioxide prepared by the method also has low specific surface area and low oil absorption and can reduce the processing cost.

Detailed Description

In order to explain the technical content, the objects and the effects of the present invention in detail, the following description will be given with reference to the embodiments.

The most key concept of the invention is as follows: the nanometer aluminum hydroxide gel is generated by mixing the water glass solution, the sulfuric acid and the aluminum sulfate according to a certain proportion under the condition of heating and alkality, and is compounded with the silicon dioxide to form a larger secondary structure polymer, so that the dispersibility and the hysteresis of the silicon dioxide in the silicon rubber are improved, and the elasticity of the silicon rubber is improved.

The invention provides a preparation method of nano silicon dioxide for high-elasticity silicone rubber, which comprises the following steps:

heating the bottom water, adding solid sodium sulfate 1-5 wt% of the bottom water, stirring to dissolve, adding water glass solution 30-50% of the bottom water, stirring to obtain reaction solution, and controlling flow rate to 3-6m³H and 10-15m³Adding dilute sulfuric acid and a water glass solution for 100-;

wherein the concentration of aluminum sulfate in the acidic aluminum sulfate solution is 14.3-38.0 wt%, and the SiO of the water glass solution₂The content of (B) is 15-25 wt%;

and adding water into the reaction slurry, washing, drying and crushing to obtain the nano silicon dioxide for the high-elasticity silicone rubber.

From the above description, the beneficial effects of the present invention are: the nano aluminum hydroxide gel is generated by mixing the water glass solution, the sulfuric acid and the aluminum sulfate according to a certain proportion under the heating condition and is compounded with the silicon dioxide to form a larger secondary structure polymer, so that the dispersibility of the silicon dioxide in the silicon rubber is improved, the agglomerates of the silicon dioxide in the silicon rubber are easy to open, the hysteresis of the silicon dioxide structure is reduced, the elasticity of a silicon rubber product can be effectively improved, and the nano silicon dioxide prepared by the method also has low specific surface area and low oil absorption and can reduce the processing cost.

Further, the concentration of the dilute sulfuric acid in the acidic aluminum sulfate solution is 5-10 wt%.

As can be seen from the above description, the content ratio of silica to alumina is adjusted by controlling the addition of water glass and the amount of acidified aluminum sulfate used by carrying out the acidification treatment with the acidic aluminum sulfate solution.

Furthermore, the water glass solution is prepared from solid water glass with the modulus of 3.0-3.6.

Further, the addition amount of the solid sodium sulfate accounts for 1.5-3% of the mass fraction of the bottom water.

From the above description, it can be known that the soluble sodium salt is added into the reaction bottom water, and the salt effect can increase the solubility of the insoluble silica, prepare large-particle secondary structure aggregates, reduce the rate of producing silica by the reaction of sodium silicate and sulfuric acid, and improve the dispersibility of silica.

Further, the preparation method of the nano silicon dioxide for the high elastic energy silicon rubber comprises the following steps:

step 1: adding dilute sulfuric acid solution and solid aluminum sulfate into a reaction kettle, and stirring to obtain acid aluminum sulfate solution with the aluminum sulfate concentration of 14.3-38.0 wt%;

step 2: putting solid sodium silicate into a static pressure kettle, introducing steam, pressurizing to 0.6-0.8MPa, adding water to prepare SiO₂A water glass solution in an amount of 15 to 25 wt%;

and step 3: firstly adding bottom water into a reaction kettle, heating to 85-95 ℃, adding solid sodium sulfate accounting for 1-5 wt% of the bottom water, stirring and dissolving, then adding water glass solution accounting for 30-50% of the volume of the bottom water, stirring uniformly to obtain reaction liquid, starting the reaction, respectively controlling the flow to be 3-6m³H and 10-15m³Adding 15-35 wt% of dilute sulfuric acid and the water glass solution to obtain a reaction solution, continuously adding for 135min, controlling the pH value of the reaction solution to be 10.0-11.0, controlling the reaction temperature to be 85-95 ℃, and controlling the reaction temperature to be 3-5m after the reaction is finished³Adding the acidic aluminum sulfate solution into the reaction liquid at a flow rate of/h, adjusting the pH value to 3-5, and aging for 30min to obtain reaction slurry;

and 4, step 4: adding water into the reaction slurry for washing until the conductivity of filtered water is less than 1000 mu S/cm to obtain spray slurry, and controlling the particle size D of the spray slurry through spray drying equipment and crushing equipment₅₀Crushing the mixture to 7-9 mu m to obtain the nano silicon dioxide for the high-elasticity silicone rubber.

From the above description, it can be known that the reaction of the water glass solution and sulfuric acid generates silicic acid, the silicic acid is very unstable and quickly aggregates into particles to become sol, the sol gels to become hydrogel to generate silica hydrogel, then a certain amount of aluminum sulfate solution is added, under the condition of heating and alkaline, nanometer aluminum hydroxide gel is generated, and the nanometer aluminum hydroxide gel and silica are compounded into a larger secondary structure aggregate.