Organic silicon defoaming agent for water-based paint and preparation method of organic silicon defoaming agent

Abstract

The invention relates to the technical field of defoaming agents. The organic silicon defoaming agent is prepared from the following raw materials in parts by weight: 150 to 170 parts of deionized water, 20 to 24 parts of polydimethylsiloxane, 15 to 20 parts of octylphenol polyoxyethylene ether, 6 to 10 parts of a sodium polyacrylate dispersing agent, 4 to 6 parts of a waterborne polyurethane thickening agent, 2 to 4 parts of a styrene-acrylic isothiazolinone preservative and 0.5 to 1 part of a first foam inhibitor, 0.1 to 0.3 part of a second foam inhibitor; according to the organic silicon defoaming agent for the water-based paint, the stability of foams can be reduced, the foams are easy to break, the generation of the foams is inhibited, the foam inhibition effect of the organic silicon defoaming agent for the water-based paint is improved, meanwhile, the stability of the foams is reduced, the foams are difficult to generate, the good foam inhibition effect is achieved, and resources are reasonably protected; the pressure of wastes on the environment is reduced, and positive effects are provided for environmental protection and sustainable development.

Description

Technical Field

[0001] The present invention relates to the technical field of defoamers, in particular to an organosilicon defoamer for water-based coatings and a preparation method thereof. Background Art

[0002] Water-based additives are an important component of water-based paint products. Their usage ratio in the formula is not high, but they can play a very critical role in improving the performance of paints and coatings. During the paint construction process, in order to reduce the generation of foam and the traces left by bubbles and form a beautiful coating, defoamers must be used in the paint. Defoamers can also improve the gloss and durability of the coating, as well as the fluidity of the paint and the dispersibility of the pigment.

[0003] In the prior art, although organosilicon defoamers for water-based coatings have good defoaming effects, they continue to generate bubbles during the flow of the liquid, resulting in poor bubble suppression. Based on this, the present invention provides an organosilicon defoamer for water-based coatings and a preparation method thereof. Summary of the invention

[0004] The object of the present invention is to provide a silicone defoamer for water-based coatings and a preparation method thereof. The defoamer prepared by the present invention not only has a good bubble suppression effect in a static state, but also has an excellent bubble suppression effect in a dynamic state, thereby effectively improving the use effect of the defoamer.

[0005] To achieve the above object, the present invention provides the following technical solutions: A silicone defoamer for water-based coatings is composed of the following raw materials in parts by weight: 150-170 parts of deionized water, 20-24 parts of polydimethylsiloxane, 15-20 parts of octylphenol polyoxyethylene ether, 6-10 parts of polyacrylic acid sodium salt dispersant, 4-6 parts of water-based polyurethane thickener, 2-4 parts of phenylisothiazolinone preservative, 0.5-1 part of a first defoamer, and 0.1-0.3 part of a second defoamer.

[0006] Preferably, the preparation method of the first foam suppressant comprises the following steps: Step 1: Recovering soap waste from a hotel, adding the waste soap to a grinder for grinding to obtain first particles; Step 2: Add the granules into the reactor, start the reactor, and continue the process for 2-3 hours at a temperature of 80-100°C and a rotation speed of 30-50 r / min to obtain a soap solution; Step 3: Add the soap solution into a stirring container and add an organic solvent. The mass ratio of the organic solvent to the soap solution is (2-3):1. After starting the stirring container, stir at a temperature of 30-50°C and a speed of 50-100 r / min for 40-60 minutes. After standing for 3-5 hours, take the supernatant and sieve to obtain a fatty acid ester turbid liquid. Step 4: Add the turbid liquid to a rotary evaporator, start the rotary evaporator, and continuously process it at a temperature of 40 - 60°C and a vacuum degree of 0.05 - 0.1 MPa to obtain a fatty acid ester concentrate, which is the first antifoaming agent. Step 5: Use a storage tank to collect the first antifoaming agent, purge it with inert gas for 5 - 20 s, and store it for later use.

[0007] In this solution, the daily remaining small pieces of waste soap in traditional hotels often exceed dozens of kilograms, and the disposal method is usually direct discard. By collecting it, the waste is effectively utilized, reducing the dependence on raw biological resources, lowering the production cost, reasonably protecting resources, reducing the pressure on the environment caused by waste, and providing a positive effect on environmental protection and sustainable development. When the fatty acid ester extracted from the waste soap raw material is added to the silicone antifoaming agent for waterborne coatings, it can replace the foaming agent molecules. In the foaming system, the foaming agent molecules will form a stable adsorption film on the surface of the bubbles, making the bubbles not easily break. However, the fatty acid ester molecules can penetrate into the bubble liquid film and form a film with poor strength. Because the fatty acid ester molecules have a typical amphiphilic structure, their adsorption method on the bubble surface and the stability of the formed film are different from those of the foaming agent, which can reduce the stability of the foam, make the foam easily break, achieve the inhibition of foam generation, and improve the antifoaming effect of the silicone antifoaming agent for waterborne coatings.

[0008] Preferably, the particle size of the first particulate matter in Step 1 is ≤100 μm, and the organic solvent selected in Step 3 is n - hexane or petroleum ether.

[0009] Preferably, the preparation method of the second antifoaming agent includes the following steps: Step 1: Recover grape seed waste from a winery, wash, remove impurities, dry, and crush it to obtain a second particulate matter. Step 2: Add the second particulate matter to a Soxhlet extractor. After premixing petroleum ether and ethyl acetate with a volume ratio of 9:1, add it to the Soxhlet extractor and continuously reflux extract at an extraction temperature of 60 - 70°C and an extraction time of 3 - 5 h to obtain an extract. Step 3: Add the extract to a rotary evaporator, start the rotary evaporator, and continuously rotary evaporate it at a temperature of 60 - 70°C and a vacuum degree of 0.03 - 0.06 MPa to obtain a crude extract. Step 4: Add the crude extract to a container, add a solvent accounting for (50 - 100)% of the mass of the crude extract for dissolution, then load it onto a silica gel column, and elute it with different polar eluents in a gradient manner to obtain a fraction containing phytosterol. Use a rotary evaporator to rotary evaporate it to obtain pure phytosterol, which is the second antifoaming agent. Step 5: Use a storage tank to collect the second antifoaming agent, purge it with inert gas for 5 - 20 s, and store it in a sealed manner for later use.

[0010] In this solution, the traditional winery produces a large amount of waste grape seeds every day when making wine. By collecting them, the waste is effectively utilized, reducing the dependence on raw biological materials, lowering the production cost, and at the same time reasonably protecting resources, reducing the pressure on the environment caused by waste, providing a positive effect on environmental protection and sustainable development. The phytosterols extracted from waste grape seeds are a class of compounds with a specific chemical structure, and their molecular structure contains hydrophobic and hydrophilic parts. This property makes phytosterols have certain surface activity in solution. When phytosterols are added to the silicone defoamer for waterborne coatings, their molecules can adsorb on the surface of the bubbles, thereby reducing the stability of the bubbles, making it difficult for bubbles to generate, and having a good defoaming effect. Moreover, phytosterols can also improve the leveling property and adhesion of waterborne coatings, improve the film-forming property and weather resistance of coatings, thereby further improving the quality and application effect of waterborne coatings, and enhancing the market competitiveness.

[0011] Preferably, the particle size of the second particulate matter in step 1 is less than or equal to 50 μm, and the inert gas in step five and step 5 can be selected from one of nitrogen, helium, and argon.

[0012] Preferably, the eluent in step 4 is made by mixing petroleum ether and ethyl acetate, and the mass ratios of petroleum ether to ethyl acetate in eluents with different polarities are 10:1, 6:1, 4:1, 3:1, 2:1, and 1:1 in sequence.

[0013] Preferably, polydimethylsiloxane and deionized water are mixed and formulated in a mass ratio of 1:(3 - 4) to obtain a first mixed solution, which is added to a mixing device and continuously stirred at a temperature of 40 - 45 °C and a stirring speed of 500 - 800 r / min for 12 - 15 min to obtain a silicone dispersion for standby.

[0014] Preferably, octylphenol polyoxyethylene ether, sodium polyacrylate dispersant, and deionized water are mixed and formulated in a mass ratio of 2:1:(5 - 6) to obtain a second mixed solution, which is added to a mixing device and continuously stirred at a temperature of 50 - 60 °C and a stirring speed of 1000 - 1200 r / min for 20 - 25 min to obtain an emulsifier dispersion for standby.

[0015] Preferably, the emulsifier dispersion is added to a homogenizing emulsifier, the initial stirring speed is 300 - 500 r / min, the silicone dispersion is added dropwise, and the stirring speed is increased to 1200 - 1400 r / min and continuously stirred for 40 - 50 min to obtain a basic mixed solution.

[0016] Furthermore, a preparation method of a silicone defoamer for waterborne coatings includes the following steps: S1: Weigh the base mixed liquid, waterborne polyurethane thickener, and phenylisothiazolinone preservative as needed and add them to a horizontal mixer for mixing. Set the temperature to ≤25°C and the speed to 300-400 r / min. Continue stirring for 20-30 minutes. S2. Add the first defoamer and the second defoamer to the horizontal mixer in S1, set the temperature to ≤30°C, and the speed to 500-600 r / min, and continue stirring until all the raw materials are completely mixed to prepare a silicone defoamer for water-based coatings.

[0017] In this scheme, when the fatty acid esters extracted from waste soap and the phytosterols extracted from waste grape seeds are further mixed in the water-based paint foaming agent, the phytosterols can be adsorbed on the surface film of the bubbles formed by the fatty acid esters. The phytosterols can reduce the elasticity and surface tension of the film, thereby further changing the physical and chemical properties of the film, and together with the fatty acid esters, prevent the foaming agent molecules from being re-adsorbed onto the bubble surface, thereby further enhancing the effect of inhibiting bubble generation.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. When the fatty acid ester extracted from the waste soap raw material is added to the organosilicon defoamer for water-based coatings, the fatty acid ester can replace the foaming agent molecules. In the foaming system, the foaming agent molecules will form a stable adsorption film on the surface of the bubble, making the bubble difficult to burst, while the fatty acid ester molecules can invade the bubble liquid film to form a film with poor strength. Because the fatty acid ester molecules have a typical amphiphilic structure, their adsorption mode on the bubble surface and the stability of the formed film are different from those of the foaming agent, which can reduce the stability of the foam and make the foam easy to burst, thereby inhibiting the generation of foam and improving the foam suppression effect of the organosilicon defoamer for water-based coatings.

[0019] 2. The phytosterols extracted from discarded grape seeds in the present invention are a class of compounds with a specific chemical structure. Their molecular structure contains hydrophobic and hydrophilic parts. This property makes the phytosterols have a certain surface activity in the solution. When the phytosterols are added to the silicone defoamer for water-based coatings, their molecules can be adsorbed on the surface of the bubbles, thereby reducing the stability of the bubbles and making it difficult for bubbles to form, which has a good anti-foaming effect. In addition, the phytosterols can also improve the leveling and adhesion of the water-based coating, improve the film-forming and weather resistance of the coating, thereby further improving the quality and application effect of the water-based coating, so that the market competitiveness is enhanced.

[0020] 3. When the fatty acid ester extracted from waste soap and the phytosterol extracted from waste grape seeds are further mixed in an aqueous coating foaming agent, the phytosterol can adsorb on the bubble surface film formed by the fatty acid ester. The phytosterol can reduce the elasticity and surface tension of the film, thereby further changing the physical and chemical properties of the film, and together with the fatty acid ester, prevent the foaming agent molecules from re-adsorbing to the bubble surface, thereby further enhancing the effect of inhibiting bubble generation.

[0021] 4. In the present invention, the extraction raw materials of the first defoaming agent and the second defoaming agent are soap waste and grape seed waste from hotels and wineries respectively. By collecting them, the waste is effectively utilized, reducing the dependence on raw biological resources, lowering the production cost, while reasonably protecting resources and reducing the pressure on the environment caused by waste, providing a positive effect for environmental protection and sustainable development. Specific embodiments

[0022] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0023] Example 1 An organosilicon defoaming agent for aqueous coatings is composed of the following raw materials in parts by weight: 150 parts of deionized water, 20 parts of polydimethylsiloxane, 15 parts of octylphenol polyoxyethylene ether, 6 parts of sodium polyacrylate dispersant, 4 parts of aqueous polyurethane thickener, 2 parts of benzisothiazolinone preservative, 0.5 part of the first defoaming agent, and 0.1 part of the second defoaming agent.

[0024] The preparation method of the first defoaming agent includes the following steps: Step 1: Recover soap waste from hotels and add it to a crusher for crushing to obtain the first particulate matter; Step 2: Add the particulate matter to a reaction kettle, start the reaction kettle, and continuously process it at a temperature of 80 °C and a rotation speed of 30 r / min for 2 h to obtain soap liquid; Step 3: Add the soap liquid to a stirring container, add an organic solvent, and the mass ratio of the organic solvent to the soap liquid is 2:1. After starting the stirring container, stir continuously at a temperature of 30 °C and a rotation speed of 50 r / min for 40 min, then let it stand for 3 h and take the supernatant, and obtain a turbid fatty acid ester solution after sieving; Step 4: Add the turbid solution to a rotary evaporator, start the rotary evaporator and continuously process it at a temperature of 40 °C and a vacuum degree of 0.05 MPa to obtain a concentrated fatty acid ester solution, which is the first defoaming agent; Step 5: Collect the first antifoaming agent using a storage tank, purge with inert gas for 5 s, and store for later use.

[0025] Among them, the particle size of the first particulate matter in Step 1 is ≤100 μm, and the organic solvent selected in Step 3 is n-hexane or petroleum ether.

[0026] The preparation method of the second antifoaming agent includes the following steps: Step 1: Recover grape seed waste from a winery, wash, remove impurities, dry, and crush it to obtain second particulate matter. Step 2: Add the second particulate matter to a Soxhlet extractor. After premixing petroleum ether and ethyl acetate with a volume ratio of 9:1, add it to the Soxhlet extractor and continuously reflux extract at an extraction temperature of 60 °C for 3 h to obtain an extract. Step 3: Add the extract to a rotary evaporator, start the rotary evaporator, and continuously rotate and evaporate at a temperature of 60 °C and a vacuum degree of 0.03 MPa to obtain a crude extract. Step 4: Add the crude extract to a container, add a solvent accounting for 50% of the mass of the crude extract for dissolution, then load it onto a silica gel column, and elute with different polar eluents in gradients to obtain a fraction containing phytosterol. Use a rotary evaporator to rotate and evaporate to obtain pure phytosterol, which is the second antifoaming agent. Among them, the solvent used to dissolve the crude extract can be selected from one of methanol and ethanol.

[0027] Step 5: Collect the second antifoaming agent using a storage tank, purge with inert gas for 5 s, and store it in a sealed manner for later use.

[0028] Among them, the particle size of the second particulate matter in Step 1 is less than or equal to 50 μm, and the inert gas in Step 5 and Step 5 can be selected from one of nitrogen, helium, and argon.

[0029] Among them, the eluent in Step 4 is made by mixing petroleum ether and ethyl acetate, and the mass ratio of petroleum ether to ethyl acetate in different polar eluents is 10:1, 6:1, 4:1, 3:1, 2:1, and 1:1 in sequence.

[0030] Among them, mix polydimethylsiloxane and deionized water in a mass ratio of 1:3 to obtain a first mixed solution, add it to a mixing device, and continuously stir at a temperature of 40 °C and a stirring speed of 500 r / min for 12 min to obtain an organosilicon dispersion for later use.

[0031] Among them, mix octylphenol polyoxyethylene ether, sodium polyacrylate dispersant, and deionized water in a mass ratio of 2:1:5 to obtain a second mixed solution, add it to a mixing device, and continuously stir at a temperature of 50 °C and a stirring speed of 1000 r / min for 20 min to obtain an emulsifier dispersion for later use.

[0032] Among them, the emulsifier dispersion liquid is added to a homogenizing emulsifier, the initial stirring speed is 300 r / min, the silicone dispersion liquid is added dropwise, and the stirring speed is increased to 1200 r / min and continuously stirred for 40 min to obtain a basic mixed liquid.

[0033] Furthermore, a preparation method of a silicone defoamer for waterborne coatings includes the following steps: S1: Weigh the basic mixed liquid, waterborne polyurethane thickener, and benzisothiazolinone preservative as needed and add them to a horizontal mixer for mixing and stirring. Set the temperature ≤ 25 °C, the rotation speed 300 r / min, and continuously stir for 20 min; S2. Add the first defoaming agent and the second defoaming agent to the horizontal mixer in S1. Under the conditions of setting the temperature ≤ 30 °C and the rotation speed 500 r / min, continuously stir until all raw materials are completely mixed to obtain a silicone defoamer for waterborne coatings.

[0034] Example 2 The preparation method of the silicone defoamer for waterborne coatings in this example is basically the same as that in Example 1, except that: the specific ratios of the raw materials used and the preparation methods of the functional additives are different. The specific ratios of the raw materials used and the preparation methods of the functional additives for preparing the silicone defoamer for waterborne coatings in this example are as follows: A silicone defoamer for waterborne coatings is composed of the following raw materials in parts by weight: 160 parts of deionized water, 22 parts of polydimethylsiloxane, 18 parts of octylphenol polyoxyethylene ether, 8 parts of sodium polyacrylate dispersant, 5 parts of waterborne polyurethane thickener, 3 parts of benzisothiazolinone preservative, 0.8 part of the first defoaming agent, and 0.2 part of the second defoaming agent.

[0035] The preparation method of the first defoaming agent includes the following steps: Step 1. Recycle soap waste from hotels and add it to a crusher for crushing to obtain first particulate matter; Step 2. Add the particulate matter to a reaction kettle, start the reaction kettle, and under the conditions of a temperature of 90 °C and a rotation speed of 40 r / min, continuously process for 2.5 h to obtain soap liquid; Step 3. Add the soap liquid to a stirring container, add an organic solvent, and the mass ratio of the organic solvent to the soap liquid is 2.5:1. After starting the stirring container, at a temperature of 40 °C and a rotation speed of 80 r / min, continuously stir for 50 min, then let it stand for 4 h and take the supernatant, and obtain a fatty acid ester turbid liquid after sieving; Step 4. Add the turbid liquid to a rotary evaporator, start the rotary evaporator and continuously process under the conditions of a temperature of 50 °C and a vacuum degree of 0.08 MPa to obtain a fatty acid ester concentrate, which is the first defoaming agent; Step 5. Use a storage tank to collect the first defoaming agent, purge it with inert gas for 12 s, and store it for use.

[0036] Among them, the particle size of the first particulate matter in Step 1 is ≤ 100 μm, and in Step 3, the organic solvent is selected from n-hexane or petroleum ether.

[0037] The preparation method of the second defoaming agent includes the following steps: Step 1: Recycle grape seed waste from a winery, wash, remove impurities, dry, and crush it to obtain the second particulate matter; Step 2: Add the second particulate matter to a Soxhlet extractor. After premixing petroleum ether and ethyl acetate with a volume ratio of 9:1, add it to the Soxhlet extractor and continuously reflux extract at an extraction temperature of 65 °C for 4 h to obtain an extract; Step 3: Add the extract to a rotary evaporator, start the rotary evaporator, and continuously rotate and evaporate at a temperature of 65 °C and a vacuum degree of 0.05 MPa to obtain a crude extract; Step 4: Add the crude extract to a container, add a solvent accounting for 80% of the mass of the crude extract to dissolve it, then load it onto a silica gel column, and elute it with different polarity eluents in gradients to obtain a fraction containing phytosterol. Use a rotary evaporator to rotate and evaporate to obtain pure phytosterol, which is the second defoaming agent; Among them, the solvent used to dissolve the crude extract can be selected from one of methanol and ethanol.

[0038] Step 5: Use a storage tank to collect the second defoaming agent, purge it with an inert gas for 15 s, and store it in a sealed manner for later use.

[0039] Among them, the particle size of the second particulate matter in Step 1 is less than or equal to 50 μm, and the inert gas in Step 5 and Step 5 can be selected from one of nitrogen, helium, and argon.

[0040] Among them, the eluent in Step 4 is made by mixing petroleum ether and ethyl acetate, and the mass ratio of petroleum ether to ethyl acetate in different polarity eluents is 10:1, 6:1, 4:1, 3:1, 2:1, and 1:1 in sequence.

[0041] Among them, mix polydimethylsiloxane and deionized water according to a mass ratio of 1:3.5 to obtain a first mixed solution, add it to a mixing device, and continuously stir at a temperature of 43 °C and a stirring speed of 700 r / min for 14 min to obtain an organosilicon dispersion for later use.

[0042] Among them, mix octylphenol polyoxyethylene ether, sodium polyacrylate dispersant, and deionized water according to a mass ratio of 2:1:5.5 to obtain a second mixed solution, add it to a mixing device, and continuously stir at a temperature of 55 °C and a stirring speed of 1100 r / min for 23 min to obtain an emulsifier dispersion for later use.

[0043] Among them, the emulsifier dispersion liquid is added to a homogenizing emulsifier. The initial stirring speed is 400 r / min. The silicone dispersion liquid is added dropwise, and the stirring speed is increased to 1300 r / min and continuously stirred for 45 min to obtain a basic mixed liquid.

[0044] Furthermore, a preparation method of an organosilicon defoamer for waterborne coatings includes the following steps: S1: Weigh the basic mixed liquid, a waterborne polyurethane thickener, and a benzisothiazolinone preservative as needed and add them to a horizontal mixer for mixing and stirring. Set the temperature ≤ 25°C and the rotation speed at 350 r / min, and continuously stir for 25 min; S2. Add a first defoaming agent and a second defoaming agent to the horizontal mixer in S1. Under the conditions of setting the temperature ≤ 30°C and the rotation speed at 550 r / min, continuously stir until all raw materials are completely mixed to obtain an organosilicon defoamer for waterborne coatings.

[0045] Example 3 In this example, the preparation method of the organosilicon defoamer for waterborne coatings is basically the same as that in Example 1, except that: the specific ratios of the raw materials used and the preparation methods of the functional additives are different. The specific ratios of the raw materials used and the preparation methods of the functional additives for preparing the organosilicon defoamer for waterborne coatings in this example are as follows: An organosilicon defoamer for waterborne coatings is composed of the following raw materials in parts by weight: 170 parts of deionized water, 24 parts of polydimethylsiloxane, 20 parts of octylphenol polyoxyethylene ether, 10 parts of sodium polyacrylate dispersant, 6 parts of waterborne polyurethane thickener, 4 parts of benzisothiazolinone preservative, 1 part of the first defoaming agent, and 0.3 part of the second defoaming agent.

[0046] The preparation method of the first defoaming agent includes the following steps: Step 1. Recycle soap waste from hotels, add it to a crusher for crushing treatment to obtain first particles; Step 2. Add the particles to a reaction kettle. Start the reaction kettle and continuously process at a temperature of 100°C and a rotation speed of 50 r / min for 3 h to obtain a soap solution; Step 3. Add the soap solution to a stirring container, add an organic solvent, and the mass ratio of the organic solvent to the soap solution is 3:1. After starting the stirring container, stir continuously at a temperature of 50°C and a rotation speed of 100 r / min for 60 min, then let it stand for 5 h and take the supernatant. After sieving, a fatty acid ester turbid liquid is obtained; Step 4. Add the turbid liquid to a rotary evaporator. Start the rotary evaporator and continuously process at a temperature of 60°C and a vacuum degree of 0.1 MPa to obtain a fatty acid ester concentrate, which is the first defoaming agent; Step 5. Use a storage tank to collect the first defoaming agent, purge it with inert gas for 20 s, and store it for later use.

[0047] The particle size of the first particles in step 1 is ≤100 μm, and the organic solvent in step 3 is n-hexane or petroleum ether.

[0048] The preparation method of the second foam suppressor comprises the following steps: Step 1: Recovering grape seed waste from a winery, washing, removing impurities, drying, and crushing to obtain a second particle; Step 2: Add the second particulate matter into a Soxhlet extractor, pre-mix petroleum ether and ethyl acetate in a volume ratio of 9:1, add the mixture into the Soxhlet extractor, and perform continuous reflux extraction at an extraction temperature of 70° C. and an extraction time of 5 h to obtain an extract; Step 3, adding the extract to a rotary evaporator, starting the rotary evaporator at a temperature of 70 degrees Celsius and a vacuum degree of 0.06 MPa to continuously rotary evaporate to obtain a crude extract; Step 4: Add the crude extract to a container, add 100% solvent by weight of the crude extract to dissolve it, and then load it onto a silica gel column. Use eluents of different polarities for gradient elution to obtain a fraction containing phytosterol. Use a rotary evaporator to evaporate the fraction to obtain pure phytosterol, which is the second antifoaming agent. The solvent for dissolving the crude extract can be selected from methanol and ethanol.

[0049] Step 5: Use a storage tank to collect the second foam suppressant, purge it with inert gas for 20 seconds, and store it in a sealed container for later use.

[0050] The particle size of the second particles in step 1 is less than or equal to 50 μm, and the inert gas in step 5 and step 5 can be selected from nitrogen, helium and argon.

[0051] Among them, the eluent in step 4 is prepared by mixing petroleum ether and ethyl acetate, and the mass ratios of petroleum ether and ethyl acetate in eluents of different polarities are 10:1, 6:1, 4:1, 3:1, 2:1 and 1:1, respectively.

[0052] Among them, polydimethylsiloxane and deionized water are mixed in a mass ratio of 1:4 to prepare a first mixed liquid, which is added to a mixing device and stirred for 15 minutes at a temperature of 45° C. and a stirring speed of 800 r / min to obtain an organosilicon dispersion for standby use.

[0053] Among them, octylphenol polyoxyethylene ether, polyacrylic acid sodium salt dispersant and deionized water are mixed in a mass ratio of 2:1:6 to obtain a second mixed liquid, which is added to a mixing device and continuously stirred for 25 minutes at a temperature of 60°C and a stirring speed of 1200 r / min to obtain an emulsifier dispersion for standby use.

[0054] Among them, the emulsifier dispersion liquid is added to a homogenizing emulsifier, the initial stirring speed is 500 r / min, the silicone dispersion liquid is added dropwise, and the stirring speed is increased to 1400 r / min and continuously stirred for 50 min to obtain a basic mixture.

[0055] Furthermore, a preparation method of a silicone defoamer for waterborne coatings includes the following steps: S1: Weigh the basic mixture, waterborne polyurethane thickener, and benzisothiazolinone preservative as needed and add them to a horizontal mixer for mixing and stirring. Set the temperature ≤ 25°C and the rotation speed 400 r / min, and continuously stir for 30 min; S2. Add the first defoaming agent and the second defoaming agent to the horizontal mixer in S1, and continuously stir until all raw materials are completely mixed under the conditions of a set temperature ≤ 30°C and a rotation speed of 600 r / min to obtain a silicone defoamer for waterborne coatings.

[0056] Comparative Example 1: The difference between this comparative example and Example 1 is that the first defoaming agent is not added in this comparative example.

[0057] Comparative Example 2: The difference between this comparative example and Example 1 is that the second defoaming agent is not added in this comparative example.

[0058] Comparative Example 3: The difference between this comparative example and Example 1 is that neither the first defoaming agent nor the second defoaming agent is added in this comparative example.

[0059] Comparative Example 4: The difference between this comparative example and Example 1 is that the soap waste and grape seed waste are not pulverized during the preparation of the first defoaming agent and the second defoaming agent in this comparative example.

[0060] Performance test: Test the relevant performances of the silicone defoamer samples for waterborne coatings provided in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 respectively; In the performance test, Static defoaming test: At room temperature, place 50 mL of a solution containing a certain amount of foam in a 100 mL beaker, add 1 g of defoamer, and record the time required for the foam to completely disappear; Dynamic defoaming test: Using a magnetic stirrer, add 2 g of defoamer to 50 mL of a coating system containing foam at a stirring speed of 500 r / min, and observe and record the foam reduction speed and the final defoaming time; Bubble suppression test: Add 1 g of defoamer to 100 mL of the foaming coating system, stir at a speed of 300 r / min for 5 minutes at room temperature using a magnetic stirrer, observe and record the amount of foam generated, and evaluate according to the area occupied by the bubbles on the liquid surface. The evaluation results are divided into A, B, and C, where grade A is the best and grade C is the worst. The obtained test data are recorded in Table 1 below: Table 1:

[0061] By comparing and analyzing the relevant data in Table 1, it can be seen that the foam suppression performance of the silicone defoamers for waterborne coatings prepared in Comparative Examples 1, 2, 3, and 4 is lower than that of Examples 1, 2, and 3. This shows that the silicone defoamer added with the first and second foam suppressants has a better bubble suppression effect. This indicates that the silicone defoamer for waterborne coatings provided by the present invention and its preparation method have a broader market prospect and are more suitable for promotion.

[0062] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0063] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An organosilicon defoamer for waterborne coatings, characterized in that: It is composed of the following raw materials in parts by weight: 150 - 170 parts of deionized water, 20 - 24 parts of polydimethylsiloxane, 15 - 20 parts of octylphenol polyoxyethylene ether, 6 - 10 parts of sodium polyacrylate dispersant, 4 - 6 parts of waterborne polyurethane thickener, 2 - 4 parts of benzisothiazolinone preservative, 0.5 - 1 part of the first defoaming agent, and 0.1 - 0.3 part of the second defoaming agent.

2. An organosilicon defoamer for waterborne coatings according to claim 1, characterized in that, The preparation method of the first defoaming agent includes the following steps: Step 1: Recycle soap waste from hotels, add it to a crusher for crushing treatment to obtain the first particulate matter; Step 2: Add the particulate matter to a reaction kettle, start the reaction kettle, and under the conditions of a temperature of 80 - 100 °C and a rotation speed of 30 - 50 r / min, continuously process for 2 - 3 h to obtain soap liquid; Step 3: Add the soap liquid to a stirring container, add an organic solvent, and the mass ratio of the organic solvent to the soap liquid is (2 - 3):

1. After starting the stirring container, at a temperature of 30 - 50 °C and a rotation speed of 50 - 100 r / min, continuously stir for 40 - 60 min, then let it stand for 3 - 5 h, and take the supernatant. After sieving, a fatty acid ester turbid liquid is obtained; Step 4: Add the turbid liquid to a rotary evaporator, start the rotary evaporator, and continuously process under the conditions of a temperature of 40 - 60 °C and a vacuum degree of 0.05 - 0.1 MPa to obtain a fatty acid ester concentrate, which is the first defoaming agent; Step 5: Use a storage tank to collect the first defoaming agent, purge it with inert gas for 5 - 20 s, and store it for use.

3. An organosilicon defoamer for waterborne coatings according to claim 2, characterized in that: The particle size of the first particulate matter in Step 1 is ≤100 μm, and the organic solvent selected in Step 3 is n - hexane or petroleum ether.

4. An organosilicon defoamer for waterborne coatings according to claim 2, characterized in that, The preparation method of the second defoaming agent includes the following steps: Step 1: Recycle grape seed waste from wineries, wash, remove impurities, dry, and crush it to obtain the second particulate matter; Step 2: Add the second particulate matter to a Soxhlet extractor. After premixing petroleum ether and ethyl acetate with a volume ratio of 9:1, add them to the Soxhlet extractor, and continuously reflux extract under the conditions of an extraction temperature of 60 - 70 °C and an extraction time of 3 - 5 h to obtain an extract; Step 3: Add the extract to a rotary evaporator, start the rotary evaporator, and continuously rotate and evaporate under the conditions of a temperature of 60 - 70 °C and a vacuum degree of 0.03 - 0.06 MPa to obtain a crude extract; Step 4: Add the crude extract to a container, add a solvent with a mass ratio of (50 - 100)% of the crude extract for dissolution, then load it onto a silica gel column, and elute it with different polarity eluents in gradients to obtain a fraction containing phytosterols. Use a rotary evaporator to rotate and evaporate to obtain pure phytosterols, which is the second defoaming agent; Step 5: Use a storage tank to collect the second defoaming agent, purge it with inert gas for 5 - 20 s, and store it in a sealed manner for use.

5. An organosilicon defoamer for waterborne coatings according to claim 1, characterized in that: The particle size of the second particulate matter in Step 1 is less than or equal to 50 μm, and the inert gas in Step 5 and Step 13 can be selected from one of nitrogen, helium, and argon.

6. An organosilicon defoamer for waterborne coatings according to claim 1, characterized in that: The eluent in Step 4 is made of a mixture of petroleum ether and ethyl acetate, and the mass ratio of petroleum ether to ethyl acetate in different polarity eluents is 10:1, 6:1, 4:1, 3:1, 2:1, and 1:1 in sequence.

7. An organosilicon defoamer for waterborne coatings according to claim 1, characterized in that: Mix polydimethylsiloxane and deionized water in a mass ratio of 1:(3 - 4) to obtain a first mixed solution, add it to a mixing device, and continuously stir at a temperature of 40 - 45 °C and a stirring speed of 500 - 800 r / min for 12 - 15 min to obtain a silicone dispersion for later use.

8. An organosilicon defoamer for waterborne coatings according to claim 1, characterized in that: Mix octylphenol polyoxyethylene ether, sodium polyacrylate dispersant and deionized water in a mass ratio of 2:1:(5 - 6) to obtain a second mixed solution, add it to a mixing device, and continuously stir at a temperature of 50 - 60 °C and a stirring speed of 1000 - 1200 r / min for 20 - 25 min to obtain an emulsifier dispersion for later use.

9. An organosilicon defoamer for waterborne coatings according to claim 8, characterized in that: Add the emulsifier dispersion to a homogenizing emulsifier, with an initial stirring speed of 300 - 500 r / min, dropwise add the silicone dispersion, increase the stirring speed to 1200 - 1400 r / min and continuously stir for 40 - 50 min to obtain a basic mixed solution.

10. The preparation method of an organosilicon defoamer for waterborne coatings according to any one of claims 1-9, characterized in that, It includes the following steps: S1: Weigh the basic mixed solution, aqueous polyurethane thickener, and benzisothiazolinone preservative as needed and add them to a horizontal mixer for mixing and stirring. Set the temperature ≤ 25 °C and the rotation speed at 300 - 400 r / min, and continuously stir for 20 - 30 min; S2. Add the first defoaming agent and the second defoaming agent to the horizontal mixer in S1, set the temperature ≤ 30 °C, and continuously stir under the condition of a rotation speed of 500 - 600 r / min until all raw materials are completely mixed to prepare an organosilicon defoaming agent for waterborne coatings.

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