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Tetraethyl Silicate Applications Properties Production
Tetraethoxysilane
Tetraethoxysilane, also known as ethyl silicate, its English name is "Tetraethyl Silicate", is widely used in the chemical industry, with both unique properties and mature production processes.
Application
1. ** Coating industry **: Tetraethoxysilane can be used as an additive for coatings. After hydrolysis and polycondensation, it can form a silicon-oxygen network structure on the surface of the coating, which greatly enhances the hardness and wear resistance of the coating. For example, adding an appropriate amount of tetraethoxysilane to the car topcoat, the car faces external friction such as wind and sand during driving, and the topcoat is more difficult to be scratched, prolonging the service life of the topcoat. Adding it to architectural exterior wall coatings can improve the adhesion and weather resistance of the coating to the wall, so that the exterior wall can still maintain good appearance and protective performance under long-term exposure to natural environments such as sun and rain.
2. ** Ceramic field **: It is an important raw material for the preparation of high-performance ceramic materials. By sol-gel method, tetraethoxysilane can be converted into ceramic precursors with high purity and uniform microstructure. When preparing electronic ceramics, using this as a raw material can precisely control the composition and microstructure of the ceramics and improve the electrical properties of the ceramics. Like making multi-layer ceramic capacitors, the ceramic medium prepared with tetraethoxysilane can effectively improve the capacitance density and stability of the capacitor.
3. ** Composite materials **: In the preparation of composite materials, tetraethoxysilane plays a key role as a coupling agent. The ethoxy group at one end can chemically react with the hydroxyl group on the surface of inorganic materials (such as glass fibers, silica, etc.), and the organic group at the other end can interact with the organic polymer matrix (such as resins, etc.). Taking glass fiber reinforced resin matrix composites as an example, tetraethoxysilane can form a strong chemical bond between glass fibers and resins, enhancing the interfacial bonding force between the two, thereby improving the mechanical properties of composites, such as tensile strength, bending strength, etc.
Properties
1. ** Physical Properties **: tetraethoxysilane is a colorless and transparent liquid at room temperature and pressure, with an odor similar to ether. Its boiling point is 168.8 ° C, and its relative density (water = 1) is 0.93. It is slightly soluble in water and can be miscible with various organic solvents such as ethanol, acetone, and benzene. The lower boiling point makes it more volatile under heating conditions, which is convenient for separation and purification by distillation in some processes. The characteristics of being slightly soluble in water make it necessary to control the reaction conditions, such as water content, catalysts, etc., during the hydrolysis reaction to achieve controlled hydrolysis.
2. ** Chemical properties **: The chemical properties are relatively active and prone to hydrolysis reactions. In the presence of water and catalysts (such as acids or bases), ethoxy groups are gradually replaced by hydroxyl groups to form silicic acid and ethanol. The hydrolysis product silicic acid is further polycondensed to form silicone polymers with different degrees of polymerization. This hydrolysis polycondensation reaction is a key reaction in many applications, and the structure and properties of the polymer can be regulated by controlling the reaction conditions (such as temperature, catalyst type and dosage, reactant ratio, etc.). For example, slowly hydrolyzed under weak acidic conditions, silicone polymers with linear structures can be obtained; while rapidly hydrolyzed under alkaline conditions, it is easy to form three-dimensional network polymers with high degree of crosslinking.
Production
1. ** Direct method **: Using silicon powder and ethanol as raw materials, tetraethoxysilane is directly reacted in the presence of a copper catalyst. The reaction equation is: $Si + 4C_ {2} H_ {5} OH\ xrightarrow {Cu} (C_ {2} H_ {5} O) _ {4} Si + 2H_ {2} $. The process is relatively simple and the atomic utilization rate is high, but it requires high reaction equipment. It needs to be carried out under high temperature and high pressure conditions, and the activity of silica powder has a great influence on the reaction. The reaction temperature is usually controlled at 200-300 ° C and the pressure is 2-5 MPa.
2. ** Indirect method **: Trichlorosilane is first prepared by the reaction of silicon powder and hydrogen chloride, and then trichlorosilane is alcoholyzed with ethanol to obtain tetraethoxysilane. The reaction is carried out in two steps, the first step: $Si + 3HCl\ xrightarrow {CuCl} SiHCl_ {3} + H_ {2} $; the second step: $SiHCl_ {3} + 4C_ {2} H_ {5} OH\ longrightarrow (C_ {2} H_ {5} O) _ {4} Si + 3HCl $. The indirect reaction conditions are relatively mild and the product purity is high, but the process is long, and the hydrogen chloride gas produced needs to be properly handled, otherwise it will cause pollution to the environment. During the production process, parameters such as reaction temperature and raw material ratio should be strictly controlled to improve product yield and quality.
Tetraethoxysilane, also known as ethyl silicate, its English name is "Tetraethyl Silicate", is widely used in the chemical industry, with both unique properties and mature production processes.
Application
1. ** Coating industry **: Tetraethoxysilane can be used as an additive for coatings. After hydrolysis and polycondensation, it can form a silicon-oxygen network structure on the surface of the coating, which greatly enhances the hardness and wear resistance of the coating. For example, adding an appropriate amount of tetraethoxysilane to the car topcoat, the car faces external friction such as wind and sand during driving, and the topcoat is more difficult to be scratched, prolonging the service life of the topcoat. Adding it to architectural exterior wall coatings can improve the adhesion and weather resistance of the coating to the wall, so that the exterior wall can still maintain good appearance and protective performance under long-term exposure to natural environments such as sun and rain.
2. ** Ceramic field **: It is an important raw material for the preparation of high-performance ceramic materials. By sol-gel method, tetraethoxysilane can be converted into ceramic precursors with high purity and uniform microstructure. When preparing electronic ceramics, using this as a raw material can precisely control the composition and microstructure of the ceramics and improve the electrical properties of the ceramics. Like making multi-layer ceramic capacitors, the ceramic medium prepared with tetraethoxysilane can effectively improve the capacitance density and stability of the capacitor.
3. ** Composite materials **: In the preparation of composite materials, tetraethoxysilane plays a key role as a coupling agent. The ethoxy group at one end can chemically react with the hydroxyl group on the surface of inorganic materials (such as glass fibers, silica, etc.), and the organic group at the other end can interact with the organic polymer matrix (such as resins, etc.). Taking glass fiber reinforced resin matrix composites as an example, tetraethoxysilane can form a strong chemical bond between glass fibers and resins, enhancing the interfacial bonding force between the two, thereby improving the mechanical properties of composites, such as tensile strength, bending strength, etc.
Properties
1. ** Physical Properties **: tetraethoxysilane is a colorless and transparent liquid at room temperature and pressure, with an odor similar to ether. Its boiling point is 168.8 ° C, and its relative density (water = 1) is 0.93. It is slightly soluble in water and can be miscible with various organic solvents such as ethanol, acetone, and benzene. The lower boiling point makes it more volatile under heating conditions, which is convenient for separation and purification by distillation in some processes. The characteristics of being slightly soluble in water make it necessary to control the reaction conditions, such as water content, catalysts, etc., during the hydrolysis reaction to achieve controlled hydrolysis.
2. ** Chemical properties **: The chemical properties are relatively active and prone to hydrolysis reactions. In the presence of water and catalysts (such as acids or bases), ethoxy groups are gradually replaced by hydroxyl groups to form silicic acid and ethanol. The hydrolysis product silicic acid is further polycondensed to form silicone polymers with different degrees of polymerization. This hydrolysis polycondensation reaction is a key reaction in many applications, and the structure and properties of the polymer can be regulated by controlling the reaction conditions (such as temperature, catalyst type and dosage, reactant ratio, etc.). For example, slowly hydrolyzed under weak acidic conditions, silicone polymers with linear structures can be obtained; while rapidly hydrolyzed under alkaline conditions, it is easy to form three-dimensional network polymers with high degree of crosslinking.
Production
1. ** Direct method **: Using silicon powder and ethanol as raw materials, tetraethoxysilane is directly reacted in the presence of a copper catalyst. The reaction equation is: $Si + 4C_ {2} H_ {5} OH\ xrightarrow {Cu} (C_ {2} H_ {5} O) _ {4} Si + 2H_ {2} $. The process is relatively simple and the atomic utilization rate is high, but it requires high reaction equipment. It needs to be carried out under high temperature and high pressure conditions, and the activity of silica powder has a great influence on the reaction. The reaction temperature is usually controlled at 200-300 ° C and the pressure is 2-5 MPa.
2. ** Indirect method **: Trichlorosilane is first prepared by the reaction of silicon powder and hydrogen chloride, and then trichlorosilane is alcoholyzed with ethanol to obtain tetraethoxysilane. The reaction is carried out in two steps, the first step: $Si + 3HCl\ xrightarrow {CuCl} SiHCl_ {3} + H_ {2} $; the second step: $SiHCl_ {3} + 4C_ {2} H_ {5} OH\ longrightarrow (C_ {2} H_ {5} O) _ {4} Si + 3HCl $. The indirect reaction conditions are relatively mild and the product purity is high, but the process is long, and the hydrogen chloride gas produced needs to be properly handled, otherwise it will cause pollution to the environment. During the production process, parameters such as reaction temperature and raw material ratio should be strictly controlled to improve product yield and quality.
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