Preparation method of hydrated silicic acid for coil coating

Abstract

The invention discloses a preparation method of hydrated silicic acid for a coil coating, which comprises the following steps: sequentially adding metal soap salt and a sodium silicate solution into a sulfuric acid solution, carrying out ultrasonic oscillation, filter pressing, water washing and microwave drying after reaction until the moisture content is below 10%, and calcining the obtained dried material to obtain the hydrated silicic acid for the coil coating. The preparation method comprises the following steps: adding a metal soap salt into silicon dioxide, reacting metal ions obtained by decomposing the metal soap salt at high temperature with hydroxyl which is not removed in the silicon dioxide to cover the hydroxyl on the surface of the silicon dioxide, and crushing to obtain the hydrated silicic acid for the coil coating. The method not only can completely remove the hydroxyl on the surface of silicon dioxide and eliminate the influence of the hydroxyl on the surface of silicon dioxide on the drying time of the coil steel coating, but also is simple to operate and easy for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrated silicate, and in particular relates to a method for preparing hydrated silicate for coil coating. Background Art

[0002] Since the 1980s, the use of highly automated roller coating for coil coating has been widely used, but this highly automated production method has put forward higher requirements on the performance of coil coatings, among which the drying time of the coating is also one of the key requirements for the performance index of coil coatings in the modern coating industry. In order to adapt to automated coating, adding a drier to coil coatings is one of the ways to improve the performance of the coating. A drier is a substance that can accelerate the drying of the coating film and catalyzes the oxygen absorption and polymerization of the dry oil film. Practical drier includes oxides, salts and organic acid soaps of metals such as cobalt, manganese, lead, iron, zinc and calcium. In order to reduce the surface defects of steel plates, adding ultrafine silica is also one of the common means. However, due to the presence of hydroxyl groups on the surface of silica, its adsorption of the drier metal salt is inevitable. Therefore, the addition of silica affects the drying time of coil coatings, which is unacceptable for coil coatings. To this end, patent CN103396694A discloses a "method for preparing a matting agent for coil coating", which uses sodium silicate and sulfuric acid as raw materials to react at 90-95°C, washes with water, dries, and calcined at 400-500°C for 3-5 hours, and then pulverizes to prepare the product. However, the hydroxyl groups on the surface of silica can only be removed at temperatures above 600°C, and only adsorbed water and part of chemically bound water can be removed below 600°C. Patent CN 101112991A discloses a method for preparing large-pore volume and large-pore silica, which is to add a hydrophobic agent (one or more of polyethylene glycol, polyvinyl alcohol, and quaternary ammonium salt water-soluble surfactants) to sodium silicate, add acid at a temperature of 50-90°C, adjust the pH to 10-12, and age for 2-4 hours to obtain the product. However, since the added active substance cannot completely react with the hydroxyl groups on the surface of silica, the drying performance of the product produced by the above patent will still be more or less affected. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a method for preparing coil coatings using hydrated silicic acid, which can not only completely remove the hydroxyl groups on the surface of silicon dioxide, but also has simple operation and is easy for industrial production.

[0004] To achieve the above object, the present invention adopts the following technical solution: A method for preparing coil coating using hydrated silicate, comprising the following steps: 1) Add metal soap salt to sulfuric acid solution, then heat to 70-80℃, then add sodium silicate solution to make the pH of the mixed solution 3-4, then at 0.5-1kg / cm 3 React under pressure for 1-2 hours, and cool to room temperature; 2) dispersing the reaction material obtained in step 1) by ultrasonic oscillation, filtering, washing with water, and then drying with microwaves until the moisture content is less than 10%; 3) The dried material in step 2) is calcined and crushed to obtain a finished product.

[0005] Furthermore, the mass concentration of the sulfuric acid solution used in step 1) is 50-60%.

[0006] Furthermore, the amount of the metal soap salt added in step 1) is 0.3-0.5% of the weight of the sulfuric acid solution; the metal soap salt is selected from at least one of calcium naphthenate and magnesium naphthenate. During high-temperature calcination, the metal soap salt will decompose, and the generated metal ions can react with the unremoved hydroxyl groups in the silicon dioxide, thereby covering the hydroxyl groups on the surface of the silicon dioxide. Therefore, in the preparation process of the present invention, the metal soap salt acts as a pore expander.

[0007] Furthermore, the mass concentration of the sodium silicate solution used in step 1) is 10-15% based on silicon dioxide.

[0008] Furthermore, in step 2), the ultrasonic oscillation time is 1-2 hours.

[0009] Furthermore, in step 2), the conductivity of the washing liquid after washing with water is below 1000 μs / cm.

[0010] Furthermore, in step 2), the temperature of the microwave drying is 300-400°C.

[0011] Furthermore, in step 3), the calcination temperature is 600-650° C. and the calcination time is 1-2 hours.

[0012] Furthermore, the average particle size of the material after crushing in step 3) is 5-6 μm.

[0013] The significant advantages of the present invention are: (1) In the field of hydrated silicate production for coil coatings, the present invention innovatively combines ultrasonic oscillation, microwave heating and calcination at above 600°C to remove hydroxyl groups on the surface of silicon dioxide.

[0014] (2) The present invention selects calcium cyclopentaneate and magnesium cyclopentaneate as metal soap salts, disperses the metal soap salts on the surface of silica first, and then thermally decomposes them so that the metal ions react with the hydroxyl groups on the surface of silica to cover the remaining hydroxyl groups. This method can not only completely remove the hydroxyl groups on the surface of silica and eliminate the influence of the hydroxyl groups on the surface of silica on the drying time of the coil coating, but also has simple operation, short process, and is easy to realize industrialization. DETAILED DESCRIPTION

[0015] A method for preparing coil coating using hydrated silicate, comprising the following steps: 1) First add 50-60% sulfuric acid solution into the reactor, then add 0.3-0.5% metal soap salt by weight of the sulfuric acid solution, heat to 70-80°C, then add 10-15% sodium silicate solution (calculated as silicon dioxide) to make the pH of the mixed solution 3-4, then keep the reactor pressure at 0.5-1kg / cm 3 , react for 1-2 hours, and cool to room temperature; 2) subjecting the reaction material obtained in step 1) to ultrasonic vibration for 1-2 hours to obtain a uniform slurry; 3) filtering the uniform slurry obtained in step 2) and then washing with water until the conductivity of the washing liquid is below 1000 μs / cm; 4) drying the washed material in step 3) by microwave at 300-400° C. until the moisture content is less than 10%; 5) heating the dried material in step 4) to 600-650°C at a rate of 10°C / min and calcining for 1-2 hours; 6) The calcined material in step 5) is crushed by a jet mill to an average particle size of 5-6 μm to obtain a finished product.

[0016] Wherein, the metal soap salt is selected from at least one of calcium naphthenate and magnesium naphthenate.

[0017] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0018] Example 1 Prepare 1000g of 50% sulfuric acid solution, add 3g of calcium cyclohexaneate, add 15% sodium silicate solution at 70℃, make the pH of the mixed solution 3.5, and heat at a pressure of 1kg / cm 3The mixture was aged for 1.5 hours under the conditions of , cooled to room temperature, and then oscillated by ultrasonic wave for 1.5 hours. After filter pressing, it was washed with water until the conductivity of the washing liquid was 900 μs / cm. The obtained material was microwave dried at 300°C to a moisture content of 9%, and then heated to 650°C at a rate of 10°C / min in a calcining furnace, calcined for 1.5 hours, and finally crushed to 5.6 μm to obtain hydrated silicate for coil coating.

[0019] Example 2 Prepare 1000g of 55% sulfuric acid solution, add 4g of calcium cyclohexaneate, add 15% sodium silicate solution at 75℃, make the pH of the mixed solution 3.2, and heat at a pressure of 0.7kg / cm 3 The mixture was aged for 1.2 hours under the conditions of , cooled to room temperature, and then oscillated by ultrasonic wave for 1.8 hours. After filter pressing, it was washed with water until the conductivity of the washing liquid was 950μs / cm. The obtained material was microwave dried at 350°C to a moisture content of 9.5%. Then, the temperature was raised to 620°C at a rate of 10°C / min in a calcining furnace, calcined for 1.5 hours, and finally crushed to 5.5μm to obtain hydrated silicate for coil coating.

[0020] Example 3 Prepare 1000g of 60% sulfuric acid solution, add 5g of calcium cyclohexaneate, add 15% sodium silicate solution at 80℃, make the pH of the mixed solution 3.0, and heat at a pressure of 0.5kg / cm 3 The product was aged for 2 hours under the conditions of , cooled to room temperature, and then oscillated by ultrasonic wave for 1 hour. After filter pressing, it was washed with water until the conductivity of the washing liquid was 930μs / cm. The obtained material was microwave dried at 400°C to a moisture content of 9%, and then heated to 600°C at a rate of 10°C / min in a calcining furnace, calcined for 2 hours, and finally crushed to 5.8μm to obtain hydrated silicate for coil coating.

[0021] Performance Testing Table 1 shows the test results of the physical and chemical properties of the coil coatings prepared in Examples 1-3 using hydrated silicate.

[0022] Table 1

[0023] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing coil coating using hydrated silicate, It is characterized in that The steps include: 1) Add metal soap salt to sulfuric acid solution, then heat to 70-80℃, then add sodium silicate solution to make the pH of the mixed solution 3-4, then at 0.5-1kg / cm 3 React under pressure for 1-2 hours, and cool to room temperature; 2) dispersing the reaction material obtained in step 1) by ultrasonic oscillation, filtering, washing with water, and then drying with microwaves until the moisture content is less than 10%; 3) The dried material in step 2) is calcined and crushed to obtain a finished product.

2. The method for preparing coil coating using hydrated silicate according to claim 1, It is characterized in that The mass concentration of the sulfuric acid solution used in step 1) is 50-60%.

3. The method for preparing coil coating using hydrated silicate according to claim 1, It is characterized in that The amount of the metal soap salt added in step 1) is 0.3-0.5% of the weight of the sulfuric acid solution; the metal soap salt is selected from at least one of calcium cyclopentaneate and magnesium cyclopentaneate.

4. The method for preparing coil coating using hydrated silicate according to claim 1, It is characterized in that The mass concentration of the sodium silicate solution used in step 1) is 10-15% based on silicon dioxide.

5. The method for preparing coil coating using hydrated silicate according to claim 1, It is characterized in that Step 2) The ultrasonic oscillation time is 1-2 hours.

6. The method for preparing coil coating using hydrated silicate according to claim 1, It is characterized in that Step 2) The conductivity of the washing liquid after washing is below 1000 μs / cm.

7. The method for preparing coil coating using hydrated silicate according to claim 1, It is characterized in that Step 2) The temperature of the microwave drying is 300-400°C.

8. The method for preparing coil coating using hydrated silicate according to claim 1, It is characterized in that Step 3) The calcination temperature is 600-650°C and the calcination time is 1-2 hours.

9. The method for preparing coil coating using hydrated silicate according to claim 1, It is characterized in that Step 3) The average particle size of the material after crushing is 5-6 μm.

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