A foaming solution and its application

Abstract

This invention relates to the technical field of flue gas filtration, specifically to a foaming solution and its application. The foaming solution comprises raw material one and betaine. By volume fraction, raw material one includes: 45%-55% polytetrafluoroethylene emulsion, 1%-5% Tween, 1%-3% methylcellulose, 3%-5% acrylic resin, and 15%-25% SiO2@PDA submicron particle emulsion, with the balance being water; the betaine mass is 1%-3% of the mass of raw material one. The coating of this invention is easier to dry, produces more uniform foam breakage, and the coated filter media exhibits better corrosion resistance and water resistance, replacing PTFE membranes and applicable to high-temperature industrial flue gas filtration.

Description

Technical Field

[0001] This invention relates to the technical field of smoke and dust filtration, and specifically to a foaming solution and its application. Background Technology

[0002] PTFE (polytetrafluoroethylene) microporous membrane composite filter media is one of the preferred materials for ultra-low emissions of industrial dust. However, PTFE-coated filter media has disadvantages such as easy breakage and poor coating adhesion. Therefore, foaming coating finishing technology has been gradually developed. Foaming coating finishing technology can replace PTFE coating and be applied to the field of high-temperature industrial dust filtration.

[0003] Chinese Patent (CN 112980313 B) discloses a foaming coating, its preparation method, and its application. The foaming coating comprises a coating body, a foam stabilizer, and bubbles. The pigment-to-binder ratio of the coating body is 1.2:1-2.5:1, and the volume fraction of the bubbles in the foaming coating is 10%-60%. This invention also relates to the preparation method and application of the foaming coating. In the foaming coating of this invention, bubbles can exist stably for more than 5 hours, and the volume fraction of bubbles can reach 10%-60%. Therefore, the foaming coating can be successfully applied in actual production.

[0004] However, the foam coating technology for filter media has the following problems: 1) The drying time is too long and the drying process is too complicated, requiring sintering and drying at temperatures above 300℃, which causes significant damage to the substrate material; 2) After the foam breaks down, the emulsion is prone to unevenness and the adhesive content is unstable, resulting in unstable surface anti-corrosion performance; 3) The prepared filter media has low waterproof and anti-corrosion performance; 4) The foam coating is difficult to store, which can easily lead to waste of resources. Summary of the Invention

[0005] To address the technical problems of poor waterproof performance and uneven coating of filter media, this invention provides a foaming solution and its application.

[0006] In a first aspect, the present invention provides a foaming solution comprising raw material one and betaine. By volume fraction, raw material one comprises: 45%-55% polytetrafluoroethylene emulsion, 1%-5% Tween, 1%-3% methylcellulose, 3%-5% acrylic resin and 15%-25% SiO2@PDA submicron particle emulsion, with the balance being water; the mass of betaine is 1%-3% of the mass of raw material one.

[0007] Further, the preparation steps include: using polytetrafluoroethylene emulsion as the main body, Tween as a foam stabilizer, methylcellulose and acrylic resin as thickeners, and adding SiO2@PDA submicron particle emulsion; after weighing, adding betaine as a foaming agent, and stirring thoroughly for 5-60 minutes to prepare a polytetrafluoroethylene foaming solution rich in SiO2@PDA submicron particles.

[0008] Furthermore, the preparation method of SiO2@PDA submicron particle emulsion is as follows:

[0009] S1. Add 0.2-0.6g of SiO2 nanoparticles to 500mL of deionized water and sonicate to make the SiO2 nanoparticles uniformly dispersed in the water.

[0010] Add 0.3-0.8g of tris(hydroxymethyl)aminomethane and 0.2-0.5g of dopamine hydrochloride to S2, heat to 35-50℃ and stir;

[0011] After the S3 polymerization reaction was completed, the product was filtered and washed three times with deionized water. Then, water was added to prepare a 30% mass fraction SiO2@PDA submicron particle emulsion.

[0012] Furthermore, the ultrasonic treatment time is 0.5-3 hours.

[0013] Furthermore, the stirring speed is 300-800 r / min, and the stirring time is 6-24 h.

[0014] Furthermore, the pore size of the filter paper during the filtration process is 0.2-0.5μm, preferably 0.45μm.

[0015] Furthermore, the preparation method of SiO2 nanoparticles is as follows:

[0016] A1. Mix 5-15 mL of tetraethyl orthosilicate and 40-50 mL of anhydrous ethanol solution and stir to form a monomer solution;

[0017] A2. Mix 20-30 mL of deionized water, 20-30 mL of anhydrous ethanol and 25-35 mL of ammonia water and stir.

[0018] A3. Pour the monomer solution into the mixed solution of A2, and stir magnetically at room temperature to obtain a white emulsion, which is the SiO2 microsphere dispersion.

[0019] A4 SiO2 microsphere dispersion was centrifuged, dried, and ground to obtain white SiO2 microsphere particles.

[0020] Furthermore, the magnetic stirring time in step A3 is 2-6 hours.

[0021] Furthermore, in step A4, the centrifugation speed is 8000-10000 r / min, the centrifugation time is 30 min, and the drying temperature is 25-50℃.

[0022] Furthermore, the foaming solution has a foaming ratio of 6-8, a density of 0.4-1 g / mL, and a bubble diameter of 0.1-0.5 mm.

[0023] Secondly, the present invention provides an application of the above-mentioned foaming liquid in the preparation of high-temperature resistant industrial dust filter media, the preparation steps of which include:

[0024] (1) Pretreatment of filter media: The filter media is impregnated with a mixture of 5%-15% polytetrafluoroethylene emulsion and 3%-7% waterproofing agent;

[0025] (2) Preparation of filter material coating: The coating roller and the scraper work together. First, the coating roller applies the foaming solution foamed by the foaming machine to the surface of the filter material. Then, the scraper controls the foam thickness on the surface of the filter material to be 1-5 mm. The filter material is dried at 140-260℃ for 10 min to obtain a coated filter material. During the drying process, the water evaporates from the surface of the coating, the foam will shrink severely, and the visible bubbles in the coating will disappear. After the foam disappears, the SiO2@PDA submicron particles will be evenly dispersed on the surface of the filter material after heating and drying, and will adhere stably. The resulting coating is more uniform and has a better waterproof effect.

[0026] Furthermore, the filter material in step (1) is a non-woven or woven fabric composed of one or more of the following materials: polyester, polyacrylonitrile, polyimide, polyphenylene sulfide, aramid, polytetrafluoroethylene, and glass fiber.

[0027] The beneficial effects of this invention are as follows:

[0028] (1) The coating of the present invention is easier to dry and the foam breaks more evenly. The filter material with the coating has better corrosion resistance and water resistance. It can replace PTFE membrane and be used for high-temperature industrial dust filtration.

[0029] (2) The foaming coating preparation process of the present invention reduces the drying temperature and drying time, thus avoiding damage to the filter material. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0031] Example 1

[0032] A method for preparing a filter media with a single-sided foamed coating for high-temperature industrial filtration includes the following steps:

[0033] (1) Pretreatment of filter media: The filter media is impregnated with a mixed emulsion of 15% polytetrafluoroethylene emulsion and 7% waterproofing agent (Zhejiang Chuanhua) by volume;

[0034] (2) Preparation of foaming liquid:

[0035] (2-1) Preparation of SiO2 nanoparticles:

[0036] A1 Add 15 mL of tetraethyl orthosilicate and 50 mL of anhydrous ethanol solution to a beaker, stir for 35 min to form a monomer solution;

[0037] A2 Add 30 mL of deionized water, 20 mL of anhydrous ethanol and 35 mL of ammonia to an Erlenmeyer flask and stir for 15 min;

[0038] A3. Pour the monomer solution into the conical flask of A2 and stir magnetically for 5 hours at room temperature. The resulting white emulsion is the SiO2 microsphere dispersion.

[0039] After centrifuging the A4 SiO2 microsphere dispersion at 10000 r / min for 30 min, drying it at 50℃, and then grinding it, white SiO2 microsphere particles were obtained.

[0040] (2-2) SiO2@PDA submicron particle emulsion:

[0041] S1. Add 0.6g of SiO2 nanoparticles to 500mL of deionized water and sonicate for 1h to make the SiO2 nanoparticles uniformly dispersed in the water.

[0042] S2 was then added with 0.8 g of tris(hydroxymethyl)aminomethane and 0.5 g of dopamine hydrochloride; the solution was then placed in a water bath and stirred at 35 °C and 600 r / min for 12 h to allow it to undergo a self-polymerization reaction.

[0043] After the S3 reaction was completed, the solution was filtered with filter paper with a pore size of 0.45 μm and the product was washed three times with deionized water to remove residual reactants. Then, water was added to prepare a 30% mass fraction SiO2@PDA submicron particle emulsion.

[0044] (2-3) A polytetrafluoroethylene foaming solution rich in SiO2@PDA submicron particles was prepared by using a 55% volume fraction polytetrafluoroethylene emulsion as the main body, a 5% volume fraction Tween as the foam stabilizer, a 3% volume fraction methylcellulose and a 5% volume fraction acrylic resin as thickeners, a 25% volume fraction and a 30% mass fraction SiO2@PDA submicron particle emulsion, with the balance being water, and finally a 3% mass fraction betaine as the foaming agent. The foaming solution had a foaming ratio of 8, a density of 1 g / mL, and a bubble diameter of 0.5 mm.

[0045] (3) Preparation of foam coating: The coating roller and the scraper work together. First, the coating roller applies the foaming solution to one side of the filter material. Then the scraper controls the foam thickness on the surface of the filter material to be 5 mm. Then, the filter material is dried at a low temperature of 260℃ for 10 min to obtain a filter material with a single-sided coating.

[0046] According to international industrial standards for waterproof rating testing, the waterproof rating of the coated side of the filter media is level 4, and the waterproof rating of the uncoated side is level 2. Liquids with different pH values ​​(pH=3, 5, 7, 9, 11) were added to the coated side of the filter media. After stabilizing for 3 minutes, the contact angle between the filter media and each droplet was observed to be greater than 90°. After stabilizing for 24 hours, the filter media showed no signs of corrosion.

[0047] Example 2

[0048] A method for preparing a filter media with a single-sided foamed coating for high-temperature industrial filtration includes the following steps:

[0049] (1) Pretreatment of filter media: The filter media is impregnated with a mixed emulsion of 5% polytetrafluoroethylene emulsion and 3% waterproofing agent (Zhejiang Chuanhua) by volume;

[0050] (2) Preparation of foaming liquid:

[0051] (2-1) Preparation of SiO2 nanoparticles:

[0052] A1 Add 5 mL of tetraethyl orthosilicate and 40 mL of anhydrous ethanol solution to a beaker, stir for 35 min to form a monomer solution;

[0053] A2 Add 20 mL of deionized water, 20 mL of anhydrous ethanol and 25 mL of ammonia to an Erlenmeyer flask and stir for 15 min;

[0054] A3. Pour the monomer solution into the conical flask of A2 and stir magnetically for 5 hours at room temperature. The resulting white emulsion is the SiO2 microsphere dispersion.

[0055] After centrifuging the A4 SiO2 microsphere dispersion at 8000 r / min for 30 min, drying it at 25-50℃, and then grinding it, white SiO2 microsphere particles were obtained.

[0056] (2-2) Preparation of SiO2@PDA submicron particle emulsion:

[0057] S1. Add 0.2g of SiO2 nanoparticles to 500mL of deionized water and sonicate for 1h to make the SiO2 nanoparticles uniformly dispersed in the water.

[0058] S2 was then added with 0.3 g of tris(hydroxymethyl)aminomethane and 0.2 g of dopamine hydrochloride; the solution was then placed in a water bath and stirred at 35 °C and 600 r / min for 12 h to allow it to undergo a self-polymerization reaction.

[0059] After the S3 reaction was completed, the solution was filtered with filter paper with a pore size of 0.45 μm and the product was washed three times with deionized water to remove residual reactants. Then, water was added to prepare a 30% mass fraction SiO2@PDA submicron particle emulsion.

[0060] (2-3) Using 45% polytetrafluoroethylene emulsion as the main body, 1% Tween by volume as a foam stabilizer, 1% methylcellulose by volume and 3% acrylic resin by volume as thickeners, 15% of the prepared SiO2@PDA submicron particle emulsion by volume was added, with the remainder being water, and finally 1% betaine by mass as a foaming agent was added. The mixture was stirred thoroughly for 15 min to prepare a polytetrafluoroethylene foaming solution rich in SiO2@PDA submicron particles; the foaming ratio was 6, the density was 0.4 g / mL, and the bubble diameter was 0.1 mm.

[0061] (3) Preparation of foam coating: The coating roller and the scraper work together. First, the coating roller applies the foaming solution to one side of the filter material. Then the scraper controls the foam thickness on the surface of the filter material to 1 mm. Then, the filter material is dried at a low temperature of 140℃ for 10 min to obtain a filter material with a single-sided coating.

[0062] According to international industrial standards for waterproof rating testing, the waterproof rating of the coated side of the filter media is level 4, and the waterproof rating of the uncoated side is level 2. Liquids with different pH values ​​(pH=3, 5, 7, 9, 11) were added to the coated side of the filter media. After stabilizing for 3 minutes, the contact angle between the filter media and each droplet was observed to be greater than 90°. After stabilizing for 24 hours, the filter media showed no signs of corrosion.

[0063] Example 3

[0064] A method for preparing a filter media with a single-sided foamed coating for high-temperature industrial filtration includes the following steps:

[0065] (1) Pretreatment of filter media: The filter media is impregnated with a mixed emulsion of 10% polytetrafluoroethylene emulsion and 5% waterproofing agent by volume;

[0066] (2) Preparation of foaming liquid:

[0067] (2-1) Preparation of SiO2 nanoparticles:

[0068] A1 Add 10 mL of tetraethyl orthosilicate and 45 mL of anhydrous ethanol solution to a beaker, stir for 35 min to form a monomer solution;

[0069] A2 Add 25 mL of deionized water, 25 mL of anhydrous ethanol and 30 mL of ammonia to an Erlenmeyer flask and stir for 15 min;

[0070] A3. Pour the monomer solution into the conical flask of A2 and stir magnetically for 5 hours at room temperature. The resulting white emulsion is the SiO2 microsphere dispersion.

[0071] After centrifuging the A4 SiO2 microsphere dispersion at 9000 r / min for 30 min, drying it at 35℃, and then grinding it, white SiO2 microsphere particles were obtained.

[0072] (2-2) SiO2@PDA submicron particle emulsion: 0.5g of SiO2 nanoparticles were added to 500mL of deionized water and sonicated for 1h to make the SiO2 nanoparticles uniformly dispersed in water; then 0.5g of tris(hydroxymethyl)aminomethane and 0.3g of dopamine hydrochloride were added; the solution was then placed in a water bath and stirred at 600r / min for 12h at 35℃ to allow it to undergo a self-polymerization reaction; after the reaction was completed, the solution was filtered through filter paper with a pore size of 0.45μm and the product was washed three times with deionized water to remove residual reactants, and then water was added to prepare a 30% mass fraction SiO2@PDA submicron particle emulsion.

[0073] (2-3) A polytetrafluoroethylene foaming solution rich in SiO2@PDA submicron particles was prepared by using a 50% volume fraction polytetrafluoroethylene emulsion as the main body, a 3% volume fraction Tween as the foam stabilizer, a 2% volume fraction methylcellulose and a 4% volume fraction acrylic resin as thickeners, a 20% volume fraction SiO2@PDA submicron particle emulsion, and the balance being water. Finally, a 2% mass fraction betaine was added as the foaming agent. The foaming solution was stirred for 15 minutes to prepare a foaming solution rich in SiO2@PDA submicron particles. The foaming ratio was 7, the density was 0.7 g / mL, and the bubble diameter was 0.3 mm.

[0074] (3) Preparation of foam coating: The coating roller and the scraper work together. First, the coating roller applies the foaming solution to one side of the filter material. Then the scraper controls the foam thickness on the surface of the filter material to be 3 mm. Then, the filter material is dried at a low temperature of 200℃ for 10 min to obtain a filter material with a single-sided coating.

[0075] According to international industrial standards for waterproof rating testing, the waterproof rating of the coated side of the filter media is level 4, and the waterproof rating of the uncoated side is level 2. Liquids with different pH values ​​(pH=3, 5, 7, 9, 11) were added to the coated side of the filter media. After stabilizing for 3 minutes, the contact angle between the filter media and each droplet was observed to be greater than 90°. After stabilizing for 24 hours, the filter media showed no signs of corrosion.

[0076] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A foaming solution, characterized in that, The mixture includes raw material one and betaine. By volume fraction, raw material one comprises: 45%-55% polytetrafluoroethylene emulsion, 1%-5% Tween, 1%-3% methylcellulose, 3%-5% acrylic resin, and 15%-25% SiO2@PDA submicron particle emulsion, with the balance being water; the mass of betaine is 1%-3% of the mass of raw material one. The preparation method of SiO2@PDA submicron particle emulsion is as follows: S1 Add 0.2-0.6g of SiO2 nanoparticles to deionized water and sonicate to make the SiO2 nanoparticles uniformly dispersed in the water. Add 0.3-0.8g of tris(hydroxymethyl)aminomethane and 0.2-0.5g of dopamine hydrochloride to S2, heat to 35-50℃ and stir; After the S3 polymerization reaction was completed, the product was filtered and washed with deionized water. Then, water was added to prepare a SiO2@PDA submicron particle emulsion. The preparation method of SiO2 nanoparticles is as follows: A1. Mix 5-15 mL of tetraethyl orthosilicate and 40-50 mL of anhydrous ethanol solution and stir to form a monomer solution; A2. Mix 20-30 mL of deionized water, 20-30 mL of anhydrous ethanol and 25-35 mL of ammonia water and stir. A3. Pour the monomer solution into the mixed solution of A2, and stir magnetically at room temperature to obtain a white emulsion, which is the SiO2 microsphere dispersion. The A4 SiO2 microsphere dispersion was centrifuged, dried, and ground to obtain white SiO2 microsphere particles.

2. The foaming solution as described in claim 1, characterized in that, The foaming solution is prepared by mixing raw material one with betaine and stirring for 5-60 minutes.

3. The foaming solution as described in claim 1, characterized in that, The ultrasonic treatment process takes 0.5-3 hours. The stirring speed is 300-800 r / min, and the time is 6-24 h. The pore size of the filter paper during the vacuum filtration process is 0.2-0.5μm.

4. The foaming solution as described in claim 1, characterized in that, The magnetic stirring time in step A3 is 2-6 hours; In step A4, the centrifugation speed is 8000-10000 r / min, the centrifugation time is 30 min, and the drying temperature is 25-50℃.

5. The foaming solution as described in claim 1, characterized in that, The foaming solution has a foaming ratio of 6-8, a density of 0.4-1 g / mL, and a bubble diameter of 0.1-0.5 mm.

6. An application of the foaming solution as described in claim 1, characterized in that, The preparation of high-temperature resistant industrial dust filter media using a foaming solution includes the following steps: (1) Pretreatment of filter media: The filter media is impregnated with a mixture of 5%-15% polytetrafluoroethylene emulsion and 3%-7% waterproofing agent; (2) Preparation of filter material coating: The coating roller and the scraper work together. First, the coating roller applies the foaming solution foamed by the foaming machine to the surface of the filter material. Then, the scraper controls the foam thickness on the surface of the filter material to be 1-5 mm. The filter material is dried at 140-260℃ for 10 min to obtain a coated filter material. During the drying process, the water evaporates from the surface of the coating, the foam will shrink severely, and the visible bubbles in the coating will disappear. After the foam disappears, the SiO2@PDA submicron particles will be evenly dispersed on the surface of the filter material after heating and drying, and will adhere stably. The resulting coating is more uniform and has a better waterproof effect.

7. The application as described in claim 6, characterized in that, The filter media is a non-woven or woven fabric composed of one or more of the following materials: polyester, polyacrylonitrile, polyimide, polyphenylene sulfide, aramid, polytetrafluoroethylene, and glass fiber.