阅读说明：本技术 一种用于橡胶补强纳米二氧化硅及其制备方法 (Nano silicon dioxide for rubber reinforcement and preparation method thereof ) 是由 汪亚雄 李智民 彭华龙 王莹莹 于 2020-05-07 设计创作，主要内容包括：本发明提供了一种用于橡胶补强的纳米二氧化硅及其制备方法。该纳米二氧化硅平均孔径≤25nm,dV/dlogD(氮吸附数据中,在80nm处对应的数值)≤1.8,氮吸附比表面为180～360m<Sup>2</Sup>/g,总孔孔容为1.1～2.0cm<Sup>3</Sup>/g,中位粒径为1.0～10μm。具体的该纳米二氧化硅通过以水玻璃和二氧化碳为原料制备,在膜分散反应釜内经多段碳化反应,再经陈化、压滤、打浆和喷雾工艺制备。本发明制备得到的纳米二氧化硅加入到橡胶组合物中,不仅能够提高橡胶的力学性能,还能降低橡胶组合物的磨耗,提高橡胶组合物的抗湿滑性能。(The invention provides nano silicon dioxide for rubber reinforcement and a preparation method thereof. The average pore diameter of the nano silicon dioxide is less than or equal to 25nm, dV/dlogD (a numerical value corresponding to a position of 80nm in nitrogen adsorption data) is less than or equal to 1.8, and the nitrogen adsorption specific surface is 180-360 m 2 The total pore volume is 1.1-2.0 cm 3 (iv) a median particle diameter of 1.0 to 10 μm. The nano silicon dioxide is prepared by taking water glass and carbon dioxide as raw materials, carrying out multistage carbonization reaction in a membrane dispersion reaction kettle, and then carrying out aging, filter pressing, pulping and spraying processes. The nano silicon dioxide prepared by the invention is added into the rubber composition, so that the mechanical property of the rubber can be improved, the abrasion of the rubber composition can be reduced, and the wet skid resistance of the rubber composition can be improved.)

1. A nanosilicon dioxide for rubber reinforcement, characterized in that: the average pore diameter of the nano silicon dioxide is less than or equal to 25nm, dV/dlogD (a numerical value corresponding to a position of 80nm in nitrogen adsorption data) is less than or equal to 1.8, and the nano silicon dioxide is used for reinforcing rubber, reducing the abrasion of the rubber and improving the wet skid resistance of the rubber.

2. The nano-silica for rubber reinforcement according to claim 1, wherein the nano-silica is prepared from water glass and carbon dioxide as raw materials by multistage carbonization in a membrane dispersion reaction kettle, aging, pressure filtration, pulping and spraying.

3. The nano-silica for rubber reinforcement according to claim 2, characterized in that: the membrane dispersion reaction kettle combines a stirring system with a membrane material, the membrane material is arranged on a rotating blade, and the average pore diameter of the membrane material is 1-50 mu m, preferably 1-20 mu m, more preferably 1-10 mu m, and particularly preferably 1-5 mu m.

4. A nano-silica for rubber reinforcement according to claim 2 or 3, wherein said multistage carbonization reaction step is divided into three steps:

firstly, introducing carbon dioxide gas at the temperature of 50-90 ℃ for 5-45 minutes;

secondly, introducing carbon dioxide gas within the range of 70-95 ℃, wherein the aeration time is 10-45 minutes;

thirdly, stirring is kept for 10 to 150 minutes within the range of 70 to 95 ℃, and the reaction is stopped when the pH value of the reaction liquid is 5.5 to 10.0.

5. The nano-silica for rubber reinforcement according to any one of claims 2 to 4, wherein the carbon dioxide gas is ordinary industrial-grade carbon dioxide, and is mixed with air to be a mixed reaction gas having a carbon dioxide volume concentration of 20 to 100 wt%.

6. The process for preparing nanosilica for rubber reinforcement according to any of claims 1 to 5, characterized by comprising the following steps:

(1) installing a dispersion membrane material on a stirring blade of a reaction kettle;

(2) conveying the water glass diluent into a reaction kettle through a pump, opening a stirring paddle and heating;

(3) opening a carbon dioxide valve, introducing carbon dioxide gas into the solution through a hollow shaft of the stirring paddle and a membrane dispersing blade, controlling the reaction temperature to be 50-90 ℃, and stopping introducing gas for 5-45 min;

(4) continuously introducing carbon dioxide gas, controlling the reaction temperature at 70-95 deg.C, introducing gas for 10-45min, and stopping introducing gas;

(5) keeping the reaction temperature within the range of 70-95 ℃, stirring for 10-150min, and stopping the reaction when the pH of the reaction solution is controlled to be 5.5-10.0;

(6) filtering and washing the reaction slurry to obtain a crude product, pulping, and spray drying to obtain the nano silicon dioxide product.

7. The preparation method according to claim 6, wherein the average pore diameter of the dispersed membrane material in the step (1) is 1-50 μm, preferably 1-20 μm, more preferably 1-10 μm, and particularly preferably 1-5 μm.

8. The preparation method according to claim 6 or 7, wherein the water glass is a first-grade sodium silicate solution with a commercial modulus of 2.0-3.4 and a Baume degree of 35-40, and the diluted solution is diluted to prepare a diluted water glass solution with a Baume degree of 2-28.

9. The method according to claim 6 or 7, wherein the carbon dioxide gas is ordinary industrial-grade carbon dioxide, and is mixed with air to form a mixed reaction gas with a carbon dioxide volume concentration of 20-100 wt%.

10. A rubber composition comprising the nano-silica according to any one of claims 1 to 5 or the nano-silica obtained by the production method according to any one of claims 6 to 9.

Technical Field

The invention relates to the technical field of rubber additives, in particular to the technical field of rubber reinforcing additives, and specifically relates to nano silicon dioxide for rubber reinforcement and a preparation method thereof.

Background

The white carbon black is amorphous silicic acid andsilicates of acid or alkaliThe product has a chemical composition of SiO₂·nH₂O is an important basic material which has excellent reinforcing performance, is often used in tires in the rubber industry, and is also used in the industries of pesticides, feeds, coatings and the like.

Along with the increasing environmental protection pressure, the problem of black pollution of the traditional tire is urgently needed to be solved, the green tire manufactured by using the high-dispersion white carbon black is more and more popular, and the green tire has the advantages of good elasticity, small rolling resistance, low oil consumption, low heat generation, wear resistance, puncture resistance, large bearing capacity, comfortable riding and the like.

At present, the main preparation methods of white carbon black include a precipitation method and a gas phase method: the precipitation method generally uses sodium silicate and sulfuric acid as raw materials, and the sodium silicate and the sulfuric acid are subjected to precipitation reaction in a solution at a high temperature and a specific temperature, and then are subjected to post-treatment such as acidification, aging, drying and the like to obtain the silicon dioxide. The gas phase method, also called combustion method, generally uses SiCl₄The raw material is prepared by carrying out gas phase hydrolysis on the raw material and a certain amount of hydrogen and oxygen (or air) at the high temperature of about 1200-1800 ℃. The precipitation method is the method with the largest industrial productivity, but the use of a large amount of sulfuric acid brings problems of corrosion of waste water and equipment and the like.

In recent years, due to the improvement of environmental protection requirements and the promotion of green chemistry concept, the process for preparing white carbon black by using carbon dioxide to replace sulfuric acid is also continuously reported:

for example, patent document CN103936015A reports a method for preparing white carbon black slurry by a spray method, and specifically, in a spray reaction tower, an atomizer atomizes a water glass solution into droplets, and then a gas containing carbon dioxide is introduced to perform an in-situ reaction in the spray drying reaction tower to prepare white carbon black. The method is to atomize and disperse the water glass in a carbon dioxide atmosphere. The disadvantage is that it is difficult to control the final pH of the reaction solution. Meanwhile, the method needs to add quaternary ammonium salt into the sodium silicate solution to promote dispersion.

Patent document CN107641217A reports a production method for preparing rubber additive by using silica fume, which aims to solve the technical obstacles of large dust consumption and high value-added utilization in the process of silicon, and specifically relates to a method for preparing white carbon black by using silica fume as a raw material and by using the reaction of silica dioxide and carbon dioxide in silica fume.

Patent document CN102320615B discloses a method for preparing white carbon black by carbonizing micro silicon powder as a raw material, which includes a carbonization reaction process and an acidification treatment process, wherein the carbonization reaction process requires addition of a surfactant, the acidification treatment process inevitably requires secondary filtration and washing, the production flow is long, the amount of filtrate and washing liquid is increased, and the problems of difficulty in industrial wastewater treatment and increase in treatment amount are caused according to different types of acid added during acidification.

Patent document CN104512896A discloses a method for preparing white carbon black by using high alumina fly ash and white carbon black, which expands the application range of the white carbon black by a carbonization method, is beneficial to green environment, and specifically requires that the modulus of desiliconized solution (i.e. water glass) is 1.5-2.5; the desiliconization liquid is subjected to two-stage heating and two-step carbonization reaction, the pH value of the final reaction is limited to 9.0-10.0, and the patent for producing the white carbon black product needs to add water again and add a modifier on the basis of a carbon filter cake, so that the process is long, the water content of the slurry is large, and the energy consumption is increased; the white carbon black prepared by the patent document has large particle size, D₅₀At more than 18 μm, dispersibility ofAnd (4) the steps are as follows.

Patent document CN108516558A reports a method for preparing ultrafine white carbon black by using water glass and carbon dioxide as raw materials, and the method has the advantages of wide raw material sources, simple production process, low cost, stable product quality, fine particle size and the like. However, the method has the same problem of low gas utilization rate as the method of CN107641217A, and carbon dioxide gas is often required to be excessively introduced to ensure the reaction, which results in low reaction efficiency and long reaction time.

CN110028074A reports a method for preparing silica by a microreactor carbonization method, specifically, a spherical silica is prepared by melting sodium silicate and a gas containing carbon dioxide into a microreactor (including a microporous reactor or a membrane dispersion microreactor) to perform carbonization reaction, aging, separating an extract, washing, and spray-drying, and has a high specific surface area, a large pore volume, good dispersibility, and a uniform mesoporous structure; the micro-reactor is utilized to improve the reaction efficiency, but the micro-reactor has the inherent defects that solid materials cannot pass through the micro-channel, and if a large amount of solids are generated in the reaction, the micro-channel is easy to block, so that the production cannot be continuously carried out.

Based on the problems in the prior art, the inventor discovers through comprehensive research of a synthesis process and a rubber formula test that: in the microscopic index of nanosilica, the pore size and the size of dV/dlogD (the corresponding value at 80nm in the nitrogen adsorption data) are closely related to its reinforcing effect in rubber.

In view of the above technical problems and the research of the inventor, the invention provides a nano material for rubber reinforcement, the average pore diameter of the prepared nano silica is less than or equal to 25nm, and dV/dlogD (the corresponding value at 80nm in nitrogen adsorption data) is less than or equal to 1.8.

The carbon dioxide is dispersed to the micron level by the membrane and enters the liquid through the stirring blades, the reaction efficiency is greatly improved, the reaction time is greatly shortened, and meanwhile, the prepared product has the advantages of high specific surface, high oil absorption value, good dispersibility, good reinforcing effect and the like.

Disclosure of Invention

In one technical scheme of the invention, the invention provides a reinforcing additive for rubber, in particular to a nano-silica reinforcing agent, wherein the average pore diameter of nano-silica is less than or equal to 25nm, and dV/dlogD (a numerical value corresponding to 80nm in nitrogen adsorption data) is less than or equal to 1.8.

The nano silicon dioxide is prepared by taking water glass and carbon dioxide as raw materials, carrying out multistage carbonization reaction in a membrane dispersion reaction kettle, and then carrying out aging, filter pressing, pulping and spraying processes.

Wherein, the membrane dispersion reaction kettle combines a stirring system with a membrane material, the membrane material is arranged on a rotating blade, and the average pore diameter of the membrane material is 1-50 μm, preferably 1-20 μm, more preferably 1-10 μm, and particularly preferably 1-5 μm.

The multi-stage carbonization reaction comprises three steps:

firstly, introducing carbon dioxide gas at the temperature of 50-90 ℃ for 5-45 minutes;

secondly, introducing carbon dioxide gas within the range of 70-95 ℃, wherein the aeration time is 10-45 minutes;

thirdly, stirring is kept for 10 to 150 minutes within the range of 70 to 95 ℃, and the reaction is stopped when the pH value of the reaction liquid is 5.5 to 10.0.

The carbon dioxide gas is common industrial carbon dioxide and is mixed with air to form mixed reaction gas with the volume concentration of the carbon dioxide of 20 wt% -100 wt%.

In another technical scheme of the invention, the invention also provides a preparation method of the nano silica for rubber reinforcement, which comprises the following steps:

(1) installing a dispersion membrane material on a stirring blade of a reaction kettle;

(2) conveying the water glass diluent into a reaction kettle through a pump, opening a stirring paddle and heating;

(3) opening a carbon dioxide valve, introducing carbon dioxide gas into the solution through a hollow shaft of the stirring paddle and a membrane dispersing blade, controlling the reaction temperature to be 50-90 ℃, and stopping introducing gas for 5-45 min;

(4) continuously introducing carbon dioxide gas, controlling the reaction temperature at 70-95 deg.C, introducing gas for 10-45min, and stopping introducing gas;

(5) keeping the reaction temperature within the range of 70-95 ℃, stirring for 10-150min, and stopping the reaction when the pH of the reaction solution is controlled to be 5.5-10.0;

(6) filtering and washing the reaction slurry to obtain a crude product, pulping, and spray drying to obtain the nano silicon dioxide product.

The water glass is a first-grade sodium silicate solution with a commercial modulus of 2.0-3.4 and a Baume degree of 35-40, and is diluted by a diluent to prepare a dilute water glass solution with a Baume degree of 2-28.

In another embodiment of the present invention, a rubber composition is also provided, which comprises the above nanosilica.

The nano silicon dioxide prepared by the method has a nitrogen adsorption specific surface of 180-360 m²The total pore volume is 1.1-2.0 cm³The average pore diameter is 5-25 nm, the median particle diameter is 1.0-10 mu m, and dV/dlogD (the corresponding numerical value at 80nm in nitrogen adsorption data) is less than or equal to 1.8; the product is verified by a rubber formula experiment, and has the advantages of good dispersibility, excellent reinforcing property, low abrasion and good wet skid resistance.

The membrane dispersion reaction kettle can improve the utilization rate and the reaction efficiency of carbon dioxide, and the principle is as follows:

according to the invention, the characteristics of the membrane and the gas are utilized, the membrane for the gas is dispersed to the micron level of 1-20, the gas and the liquid are mixed in the reaction container through the stirring blade, and a local turbulent flow and a micron level laminar flow are formed at the thin surface parallel to the stirring blade, so that the carbon dioxide can be uniformly dispersed in the solution, and the reaction efficiency is greatly improved. The method specifically comprises the following steps: the membrane dispersion material is arranged on the rotating blade, carbon dioxide gas enters the blade from the main shaft, and in the rotating state of the blade, the gas enters the solution after being dispersed by the membrane to reach a micron-sized gas column, so that the range of the blade close to the membrane material is in a micron-sized layer and is uniformly dispersed, and the whole solution is in radial flow and axial flow in the reactor, so that the reacted slurry is uniformly mixed; furthermore, the method reasonably controls the carbonization reaction steps, including setting multiple carbonization steps, and reasonably controlling the reaction temperature and the ventilation time of each carbonization step so as to avoid the problems of equipment blockage and the like.

Compared with other processes for preparing white carbon black by a carbonization method, the method has the following advantages:

1. high reaction efficiency and high utilization rate of carbon dioxide.

2. The process can realize the dispersion of carbon dioxide film gas and the uniform mixing of gas and liquid phases.

3. The product with good dispersibility can be obtained without adding additives such as quaternary ammonium salt and the like, and through rubber formula experiments, all indexes exceed those of common white carbon black products.

4. The average pore diameter of the nano silicon dioxide prepared by the method is less than or equal to 25nm, dV/dlogD (a corresponding numerical value at 80nm in nitrogen adsorption data) is less than or equal to 1.8, and the particle size (D50) is controllable to be 1.0-10 mu m.

The nano silicon dioxide prepared by the invention is added into the rubber composition, so that the mechanical property of the rubber can be improved, the abrasion of the rubber composition can be reduced, and the wet skid resistance of the rubber composition can be improved.

Drawings

FIG. 1 is a scanning image of a transmission electron microscope of nano-silica prepared in example 1.

Detailed Description

1. The specific embodiment is as follows: