A modified silicone defoamer and its preparation method

Abstract

The present invention relates to the technical field of defoamers, and discloses a modified silicone defoamer and a preparation method thereof. The modified silicone defoamer uses hydrogen-containing silicone oil as the base material, and is modified with polyether-modified carboxymethyl cellulose and modified silica to obtain the modified silicone defoamer. After the silica is modified, it is uniformly and stably distributed in the system, improving the defoaming efficiency. Carboxymethyl cellulose has excellent thickening, film-forming and stability properties, which can increase the consistency of the silicone defoamer, help form a stable film layer, contribute to the adhesion and dispersion of the active ingredients of the defoamer, and improve the defoaming effect. The silicone modified by polyether has improved surface properties, better hydrophilicity and wettability, and improved structural stability of the silicone oil. The various components synergistically enhance the effect. The prepared modified silicone has excellent defoaming and foam suppression effects, good dispersibility, improved heat resistance and stability, and a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the technical field of defoamers, and particularly to a modified silicone defoamer and a preparation method thereof. Background Art

[0002] In industrial production, various problems often occur due to the generation of foam in many technological processes, which even affect the product quality. Therefore, it is of great significance to eliminate and inhibit the generation of harmful foam. Industrially, mechanical and chemical methods are usually used to eliminate harmful foam. Mechanical defoaming can only remove surface foam in a short time and is difficult to eliminate internal foam. Chemical defoaming is to add a defoamer to the foam system to destroy and inhibit the formation of the bubble wall film to achieve the purpose of defoaming. There are many types of defoamers, and the commonly used ones in industry include mineral oil defoamers, silicone defoamers, and polyether defoamers. Among them, silicone defoamers have excellent defoaming and foam inhibition effects due to their low surface tension and good chemical stability. However, silicone defoamers have poor dispersibility in water and poor high-temperature resistance, and their stability is affected, which greatly limits the application of silicone defoamers.

[0003] Chinese Patent Application CN116196658A discloses the synthesis of a defoamer with excellent defoaming performance. The defoamer includes polyether, modified nano-silica, a composite emulsifier, hydrophobic particles, and a solvent; the polyether includes fatty alcohol-modified polyether and organosilane-modified polyether, and the composite emulsifier includes sucrose fatty acid ester, polyethylene glycol dilaurate, and Tween 80. This defoamer has strong defoaming performance, rapid foam breaking, and long foam inhibition time, but the dispersibility of modified nano-silica and hydrophobic particle silica white carbon is poor, which affects the overall performance of the defoamer. Chinese Patent Application CN103830938A discloses a preparation method of a silicone defoamer. The silicone defoamer is a stable emulsion prepared by emulsifying components such as dimethyl silicone oil and non-ionic surfactants, and has the characteristics of fast defoaming speed and strong foam inhibition ability, but its stability and high-temperature resistance are poor, and it is easy to demulsify, float oil, and precipitate at high temperatures, which affects the quality and use value of the production finished product and is not conducive to popularization and use. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] In order to solve the above technical problems, the present invention provides a modified silicone defoamer and a preparation method thereof. The prepared modified silicone defoamer has excellent defoaming and foam inhibition effects, and at the same time has good heat resistance and stability.

[0006] (II) Technical Solutions

[0007] In order to achieve the above object, the present invention discloses a preparation method of a modified silicone defoamer, which includes the following steps:

[0008] Step 1: Ultrasonically disperse fumed silica in an ethanol solution. After uniform dispersion, add 1H,1H,2H,2H-perfluorooctyltriethylsilane and γ-(methacryloyloxy)propyltrimethoxysilane, mix uniformly, adjust the pH of the solution to 5 with acetic acid, raise the temperature, and carry out the reaction. After the reaction is completed, wash with absolute ethanol, centrifuge, and vacuum dry at 60 °C for 12 h to obtain modified fumed silica;

[0009] Step 2: Mix carboxymethyl cellulose and deionized water uniformly, then add acrylamide and glycidyl methacrylate and stir to mix. Pass in nitrogen, and in a nitrogen atmosphere, add a crosslinking agent and an initiator, stir to mix, and carry out the reaction. After the reaction is completed, wash with deionized water and absolute ethanol, and vacuum dry at 60 °C for 6 h to obtain epoxy-modified carboxymethyl cellulose;

[0010] Step 3: Mix epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether, and ethylenediamine uniformly, heat under reflux, and carry out the reaction. After the reaction is completed, carry out suction filtration, wash with absolute ethanol and deionized water, and vacuum dry at 60 °C for 12 h to obtain polyether-modified carboxymethyl cellulose;

[0011] Step 4: Mix hydrogen-containing silicone oil, polyether-modified carboxymethyl cellulose, modified fumed silica, and chloroplatinic acid, heat, and carry out the reaction. After the reaction is completed, obtain a modified silicone defoamer.

[0012] Preferably, the mass ratio of fumed silica, ethanol solution, 1H,1H,2H,2H-perfluorooctyltriethylsilane, and γ-(methacryloyloxy)propyltrimethoxysilane in Step 1 is 100:3500 - 4200:8 - 14:25 - 42.

[0013] Preferably, the reaction temperature in Step 1 is 75 - 85 °C, and the reaction time is 30 - 36 h.

[0014] Preferably, the ethanol solution in Step 1 is a 75% ethanol aqueous solution.

[0015] Preferably, the acetic acid concentration in Step 1 is 0.1 mol / L.

[0016] Preferably, the mass ratio of carboxymethyl cellulose, deionized water, acrylamide, glycidyl methacrylate, crosslinking agent, and initiator in Step 2 is 100:3200 - 3500:12 - 15:38 - 55:0.1 - 0.2:3 - 6.

[0017] Preferably, the reaction temperature in Step 2 is 75 - 85 °C, and the reaction time is 1 - 2 h.

[0018] Preferably, the crosslinking agent in Step 2 is N,N'-methylenebisacrylamide, and the initiator is ammonium persulfate.

[0019] Preferably, in the step three, the mass ratio of the epoxy-modified carboxymethyl cellulose, the alkenyl-terminated epoxy polyether and the ethylenediamine is 100:118 - 140:185 - 235.

[0020] Preferably, in the step three, the reaction temperature is 85 - 95 °C and the reaction time is 12 - 18 h.

[0021] Preferably, in the step four, the mass ratio of the hydrogen-containing silicone oil, the polyether-modified carboxymethyl cellulose, the modified silica and the chloroplatinic acid is 100:18 - 25:3 - 7:0.2 - 0.5.

[0022] Preferably, in the step four, the reaction temperature is 90 - 150 °C and the reaction time is 10 - 15 h.

[0023] A modified silicone defoamer prepared by using the preparation method of the modified silicone defoamer described above.

[0024] (III) Beneficial technical effects

[0025] (1) In the present invention, 1H,1H,2H,2H-perfluorooctyltriethylsilane and γ-(methacryloyloxy)propyltrimethoxysilane are used to modify silica, introducing fluorine atoms, long-chain alkanes, alkenyl groups and silanes on the surface of silica to obtain modified silica. Carboxymethyl cellulose, acrylamide and glycidyl methacrylate polymerize under the action of a crosslinking agent and an initiator to introduce epoxy groups onto the carboxymethyl cellulose to obtain epoxy-modified carboxymethyl cellulose. The epoxy groups on the epoxy-modified carboxymethyl cellulose and the epoxy groups on the alkenyl-terminated epoxy polyether react with the amino groups on the ethylenediamine to obtain polyether-modified carboxymethyl cellulose, introducing alkenyl groups and polyethers onto the carboxymethyl cellulose. The alkenyl groups on the polyether-modified carboxymethyl cellulose and the modified silica undergo an addition reaction with the hydrogen-containing silicone oil under the catalysis of chloroplatinic acid to obtain the modified silicone defoamer.

[0026] (2) In the present invention, silica is introduced into the defoamer, and a large number of fluorine atoms and long alkyl chains are introduced onto the surface of the silica. The modified silica has excellent hydrophobicity, which can reduce the degree of association of silica in the water system and has excellent defoaming effect. Due to its small particle size, large specific surface area, high surface energy and three-dimensional network structure, silica can effectively adsorb bubbles, and under the action of the low surface force of silicone oil, the bubbles will burst. Further, after the silica is modified, it can be evenly and stably distributed in the system, greatly improving the defoaming efficiency. Carboxymethyl cellulose has excellent thickening, film-forming and stability properties, which can increase the consistency of the silicone defoamer system, help form a stable film layer, contribute to the attachment and dispersion of the active ingredients of the defoamer, thereby improving the defoaming effect, and at the same time can also improve the stability of the system. Hydrogen-containing silicone oil can be used for defoaming in both water systems and oil systems, with a wide range of applications. The surface tension of hydrogen-containing silicone oil is relatively low, which enables it to more effectively reduce the surface tension of the foaming system, effectively break the already generated bubbles, prevent the generation of bubbles, play a defoaming role, and at the same time can also inhibit the generation of bubbles, reduce the bubbles in the system, and hydrogen-containing silicone oil has high heat resistance and can maintain stable performance within a wide temperature range.

[0027] (3) In the present invention, carboxymethyl cellulose is grafted onto silicone oil, which can firmly attach the active ingredients of the defoamer to the carrier, prevent them from falling off or being unevenly dispersed during use. Carboxymethyl cellulose can also protect the active ingredients of the defoamer from external environmental interference and extend its service life. Introducing polyether onto carboxymethyl cellulose not only introduces reactive groups for the next reaction. Further, the surface properties of the silicone modified by polyether are improved, with better hydrophilicity and wettability. The surface activity of polyether-modified silicone is strong, which can rapidly reduce the surface tension of the liquid, making the bubbles easier to break, improving the defoaming efficiency, and at the same time can improve its heat resistance and chemical stability, broadening the scope of use of the defoamer.

[0028] (4) After the polyether-modified carboxymethyl cellulose reacts with the modified silica and hydrogen-containing silicone oil in the present invention, the structural stability of the silicone is improved, and it is not easy to chemically react with other substances, and can maintain its performance unchanged in different chemical environments, thus ensuring the durability of the defoaming effect. The various components in the prepared modified silicone defoamer synergistically enhance the effect, having excellent defoaming and foam inhibition effects, good dispersibility, improved heat resistance and stability, and a wide range of applications. Detailed implementation mode

[0029] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. 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 efforts belong to the scope of protection of the present invention.

[0030] Example 1

[0031] A preparation method of a modified silicone defoamer includes the following steps:

[0032] Step 1: Ultrasonically disperse fumed silica into an ethanol solution, where the ethanol solution is a 75% ethanol aqueous solution. After uniform dispersion, add 1H,1H,2H,2H-perfluorooctyltriethylsilane and γ-(methacryloyloxy)propyltrimethoxysilane. The mass ratio of fumed silica, ethanol solution, 1H,1H,2H,2H-perfluorooctyltriethylsilane, and γ-(methacryloyloxy)propyltrimethoxysilane is 100:3500:8:25. Mix uniformly, adjust the pH of the solution to 5 with acetic acid, the concentration of acetic acid is 0.1 mol / L, heat up, react at 75°C for 36 h. After the reaction is completed, wash with absolute ethanol, centrifuge, and vacuum dry at 60°C for 12 h to obtain modified fumed silica;

[0033] Step 2: Mix carboxymethyl cellulose and deionized water uniformly, then add acrylamide and glycidyl methacrylate and stir to mix. Pass in nitrogen, and in a nitrogen atmosphere, add N,N'-methylenebisacrylamide and ammonium persulfate. The mass ratio of carboxymethyl cellulose, deionized water, acrylamide, glycidyl methacrylate, N,N'-methylenebisacrylamide, and ammonium persulfate is 100:3200:12:38:0.1:3. Stir to mix and react at 75°C for 2 h. After the reaction is completed, wash with deionized water and absolute ethanol, and vacuum dry at 60°C for 6 h to obtain epoxy-modified carboxymethyl cellulose;

[0034] Step 3: Mix epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether, and ethylenediamine with a mass ratio of 100:118:185 uniformly, heat under reflux, and react at 85°C for 18 h. After the reaction is completed, filter by suction, wash with absolute ethanol and deionized water, and vacuum dry at 60°C for 12 h to obtain polyether-modified carboxymethyl cellulose;

[0035] Step 4: Mix hydrogen-containing silicone oil, polyether-modified carboxymethyl cellulose, modified fumed silica, and chloroplatinic acid with a mass ratio of 100:18:3:0.2, heat, and react at 90°C for 15 h. After the reaction is completed, obtain the modified silicone defoamer.

[0036] Example 2

[0037] A preparation method of a modified silicone defoamer comprises the following steps:

[0038] Step 1: Ultrasonically disperse fumed silica into an ethanol solution, where the ethanol solution is a 75% ethanol aqueous solution. After uniform dispersion, add 1H,1H,2H,2H-perfluorooctyltriethylsilane and γ-(methacryloyloxy)propyltrimethoxysilane. The mass ratio of fumed silica, ethanol solution, 1H,1H,2H,2H-perfluorooctyltriethylsilane, and γ-(methacryloyloxy)propyltrimethoxysilane is 100:4000:12:32. Mix uniformly, adjust the pH of the solution to 5 with acetic acid, where the acetic acid concentration is 0.1 mol / L. Heat up and react at 80 °C for 32 h. After the reaction ends, wash with absolute ethanol, centrifuge, and vacuum dry at 60 °C for 12 h to obtain modified fumed silica;

[0039] Step 2: Mix carboxymethyl cellulose and deionized water uniformly, then add acrylamide and glycidyl methacrylate and stir to mix. Pass in nitrogen. In a nitrogen atmosphere, add N,N'-methylenebisacrylamide and ammonium persulfate. The mass ratio of carboxymethyl cellulose, deionized water, acrylamide, glycidyl methacrylate, N,N'-methylenebisacrylamide, and ammonium persulfate is 100:3400:13:42:0.15:4. Stir to mix and react at 80 °C for 1.5 h. After the reaction ends, wash with deionized water and absolute ethanol, and vacuum dry at 60 °C for 6 h to obtain epoxy-modified carboxymethyl cellulose;

[0040] Step 3: Mix epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether, and ethylenediamine with a mass ratio of 100:125:205 uniformly, heat under reflux, and react at 90 °C for 14 h. After the reaction ends, filter by suction, wash with absolute ethanol and deionized water, and vacuum dry at 60 °C for 12 h to obtain polyether-modified carboxymethyl cellulose;

[0041] Step 4: Mix hydrogen-containing silicone oil, polyether-modified carboxymethyl cellulose, modified fumed silica, and chloroplatinic acid with a mass ratio of 100:21:4:0.3, heat, and react at 105 °C for 12 h. After the reaction ends, obtain the modified silicone defoamer.

[0042] Example 3

[0043] A preparation method of a modified silicone defoamer comprises the following steps:

[0044] Step 1: Mix carboxymethyl cellulose and deionized water evenly, then add acrylamide and glycidyl methacrylate and stir to mix. Introduce nitrogen gas. In a nitrogen atmosphere, add N,N'-methylenebisacrylamide and ammonium persulfate. The mass ratio of carboxymethyl cellulose, deionized water, acrylamide, glycidyl methacrylate, N,N'-methylenebisacrylamide, and ammonium persulfate is 100:3400:14:50:0.15:5. Stir to mix and react at 80 °C for 1.5 h. After the reaction, wash with deionized water and absolute ethanol and vacuum dry at 60 °C for 6 h to obtain epoxy-modified carboxymethyl cellulose;

[0045] Step 2: Mix epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether, and ethylenediamine with a mass ratio of 100:135:225 evenly, heat under reflux, and react at 90 °C for 16 h. After the reaction, filter by suction, wash with absolute ethanol and deionized water, and vacuum dry at 60 °C for 12 h to obtain polyether-modified carboxymethyl cellulose;

[0046] Step 3: Mix hydrogen-containing silicone oil, polyether-modified carboxymethyl cellulose, modified silica, and chloroplatinic acid with a mass ratio of 100:21:4:0.3, heat, and react at 105 °C for 12 h. After the reaction, obtain the modified silicone defoamer.

[0047] The preparation method of the modified silica is the same as that of the modified silica in Example 2.

[0048] Example 4

[0049] A preparation method of a modified silicone defoamer, comprising the following steps:

[0050] Step 1: Mix hydrogen-containing silicone oil, polyether-modified carboxymethyl cellulose, modified silica, and chloroplatinic acid with a mass ratio of 100:24:6:0.4, heat, and react at 135 °C for 14 h. After the reaction, obtain the modified silicone defoamer.

[0051] The preparation methods of the modified silica and polyether-modified carboxymethyl cellulose are the same as those of the modified silica in Example 3.

[0052] Example 5

[0053] A preparation method of a modified silicone defoamer, comprising the following steps:

[0054] Step 1: Disperse fumed silica into an ethanol solution. The ethanol solution is a 75% ethanol aqueous solution. After uniform dispersion, add 1H,1H,2H,2H-perfluorooctyltriethylsilane and γ-(methacryloyloxy)propyltrimethoxysilane. The mass ratio of fumed silica, ethanol solution, 1H,1H,2H,2H-perfluorooctyltriethylsilane, and γ-(methacryloyloxy)propyltrimethoxysilane is 100:4200:14:42. Mix uniformly, adjust the pH of the solution to 5 with acetic acid, and the concentration of acetic acid is 0.1 mol / L. Heat up and react at 85°C for 30 h. After the reaction, wash with absolute ethanol, centrifuge, and vacuum dry at 60°C for 12 h to obtain modified fumed silica;

[0055] Step 2: Mix carboxymethyl cellulose and deionized water uniformly, then add acrylamide and glycidyl methacrylate and stir to mix. Pass in nitrogen. In a nitrogen atmosphere, add N,N'-methylenebisacrylamide and ammonium persulfate. The mass ratio of carboxymethyl cellulose, deionized water, acrylamide, glycidyl methacrylate, N,N'-methylenebisacrylamide, and ammonium persulfate is 100:3500:15:55:0.2:6. Stir and mix, and react at 85°C for 1 h. After the reaction, wash with deionized water and absolute ethanol, and vacuum dry at 60°C for 6 h to obtain epoxy-modified carboxymethyl cellulose;

[0056] Step 3: Mix epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether, and ethylenediamine with a mass ratio of 100:140:235 uniformly, heat under reflux, and react at 95°C for 12 h. After the reaction, filter by suction, wash with absolute ethanol and deionized water, and vacuum dry at 60°C for 12 h to obtain polyether-modified carboxymethyl cellulose;

[0057] Step 4: Mix hydrogen-containing silicone oil, polyether-modified carboxymethyl cellulose, modified fumed silica, and chloroplatinic acid with a mass ratio of 100:25:7:0.5, heat, and react at 150°C for 10 h. After the reaction, obtain a modified silicone defoamer.

[0058] Comparative Example 1

[0059] A preparation method of a silicone defoamer, comprising the following steps:

[0060] Step 1: Mix carboxymethyl cellulose and deionized water evenly, then add acrylamide and glycidyl methacrylate and stir to mix. Introduce nitrogen gas. In a nitrogen atmosphere, add N,N'-methylenebisacrylamide and ammonium persulfate. The mass ratio of carboxymethyl cellulose, deionized water, acrylamide, glycidyl methacrylate, N,N'-methylenebisacrylamide, and ammonium persulfate is 100:3400:14:50:0.15:5. Stir and mix, and react at 80 °C for 1.5 h. After the reaction, wash with deionized water and absolute ethanol, and vacuum dry at 60 °C for 6 h to obtain epoxy-modified carboxymethyl cellulose;

[0061] Step 2: Mix epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether, and ethylenediamine with a mass ratio of 100:135:225 evenly, heat under reflux, and react at 90 °C for 16 h. After the reaction, filter by suction, wash with absolute ethanol and deionized water, and vacuum dry at 60 °C for 12 h to obtain polyether-modified carboxymethyl cellulose;

[0062] Step 3: Mix hydrogen-containing silicone oil, polyether-modified carboxymethyl cellulose, fumed silica, and chloroplatinic acid with a mass ratio of 100:24:6:0.4, heat, and react at 135 °C for 14 h. After the reaction, obtain an organosilicon defoamer.

[0063] Comparative Example 2

[0064] A preparation method of an organosilicon defoamer includes the following steps:

[0065] Step 1: Ultrasonically disperse fumed silica into an ethanol solution, where the ethanol solution is a 75% ethanol aqueous solution. After dispersing evenly, add 1H,1H,2H,2H-perfluorooctyltriethylsilane and γ-(methacryloyloxy)propyltrimethoxysilane. The mass ratio of fumed silica, ethanol solution, 1H,1H,2H,2H-perfluorooctyltriethylsilane, and γ-(methacryloyloxy)propyltrimethoxysilane is 100:4000:12:32. Mix evenly, adjust the pH of the solution to 5 with acetic acid, the concentration of acetic acid is 0.1 mol / L, raise the temperature, and react at 80 °C for 32 h. After the reaction, wash with absolute ethanol, centrifuge, and vacuum dry at 60 °C for 12 h to obtain modified fumed silica;

[0066] Step 2: Mix hydrogen-containing silicone oil, carboxymethyl cellulose, alkenyl-terminated epoxy polyether, modified fumed silica, and chloroplatinic acid with a mass ratio of 100:10:14:6:0.4, heat, and react at 135 °C for 14 h. After the reaction, obtain an organosilicon defoamer.

[0067] Comparative Example 3

[0068] A preparation method of an organosilicon defoamer, comprising the following steps:

[0069] Step 1: Mix hydrogen-containing silicone oil, carboxymethyl cellulose, alkenyl-terminated epoxy polyether, fumed silica and chloroplatinic acid with a mass ratio of 100:10:14:6:0.4, heat, and react at 135 °C for 14 h. After the reaction, an organosilicon defoamer is obtained.

[0070] In the examples and comparative examples of the present invention, the fumed silica is fumed silica with a particle size of 7-40 nm, purchased from Guangzhou Gibisheng Technology Co., Ltd., the carboxymethyl cellulose is purchased from Chengdu Kelong Chemical Reagent Co., Ltd., and the alkenyl-terminated epoxy polyether is purchased from Hangzhou Diweilai Trading Co., Ltd.; the hydrogen-containing silicone oil is purchased from Tianjin Yimeike Fine Chemical Factory (hydrogen mass fraction 0.2-1.0%, viscosity at 25 °C 10-30 mPa·s); other reagents not disclosed are commercially available.

[0071] Perform corresponding tests on the organosilicon defoamers prepared in Examples 1-5 and Comparative Examples 1-3. The test methods and test results are as follows:

[0072] (1) Defoaming performance test: Weigh 50 g of the foaming liquid with a 100 mL stoppered graduated cylinder, add 0.05 g of the defoamers prepared in Examples 1-5 and Comparative Examples 1-3 respectively, keep the temperature constant at 25 °C and 80 °C in a water bath respectively, cover the bottle stopper, and vertically shake the graduated cylinder up and down 10 times at a frequency of 2 times / s and a swing amplitude of 30-35 cm. Let it stand and start timing with a stopwatch, and record the time taken for the foam to disappear until the liquid surface appears;

[0073] (2) Foam suppression performance test: Use a lubricating oil foam characteristic tester that meets the requirements of GB / T 12579. Set the constant water bath temperature of the instrument to 25 °C and 80 °C respectively, the test gas flow rate to 100 mL / min, weigh 100 g of the foaming liquid, weigh 0.1 g of the defoamers prepared in Examples 1-5 and Comparative Examples 1-3 respectively, add them to the foaming liquid, stir evenly, then pour them into a clean bubbling instrument graduated cylinder, keep the temperature constant at 25 °C and 80 °C respectively, turn on the flow pump, start the test, and record the foam volume (mL) after 30 min of air bubbling. The foam suppression performance is represented by the foam volume corresponding to 30 min of air bubbling;

[0074] (3) Stability test: Take 15 mL of the defoamers prepared in Examples 1-5 and Comparative Examples 1-3 in centrifuge tubes respectively, centrifuge them in a high-speed centrifuge at a speed of 3000 r / min, stop and observe once every 5 min, continuously centrifuge for 30 min to observe whether there is stratification. Dilute the defoamer stock solution 50 times with deionized water, stir evenly with a glass rod, let it stand for 48 h, and observe whether there is stratification or demulsification. The test temperatures are 25 °C and 80 °C respectively;

[0075] The above test results are shown in Table 1 as follows:

[0076] Table 1

[0077]

[0078] From the test results in Table 1, it can be seen that the defoamers corresponding to Examples 1-5 do not delaminate after continuous centrifugation for 30 minutes, have excellent stability, and have excellent defoaming performance and foam suppression performance. They defoam rapidly, have a good foam suppression effect, and can still maintain excellent comprehensive performance under high-temperature conditions, indicating good heat resistance. In Comparative Example 1, the silica white was not modified, and the surface silanol groups (Si-OH) had high activity and were prone to form hydrogen bonds with water molecules. However, at the same time, its dispersibility in the water system was limited, and its compatibility with hydrogen-containing silicone oil was poor, resulting in the instability of the defoamer in the system, easy delamination or precipitation, affecting the defoaming performance, and the stability, defoaming performance, and foam suppression performance of the defoamer were all reduced. In Comparative Example 2, the carboxymethyl cellulose was not modified, and its solubility was poor. The active groups on the molecular chain might interact with other components in the system, resulting in a decrease in the system stability. The alkenyl-terminated epoxy polyether and modified silica white could undergo an addition reaction with hydrogen-containing silicone oil, which had an impact on the overall performance of the defoamer, and the comprehensive performance became worse. In Comparative Example 3, neither the silica white nor the carboxymethyl cellulose was modified, and the comprehensive performance was significantly worse. At 25°C, the defoaming time was 14 s, the foam suppression performance was 345 mL, the stability decreased, and obvious delamination occurred, being unstable. At 80°C, the defoaming time was 15 s, the foam suppression performance was 351 mL, the stability decreased, and obvious delamination occurred, being unstable.

[0079] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention application shall still fall within the scope covered by the present invention.

Claims

1. A method for preparing a modified organosilicon defoamer, characterized in that: The steps include: Step 1, ultrasonically disperse white carbon black in an ethanol solution, and after uniform dispersion, add 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane and γ-(methacryloyloxy) propyl trimethoxy silane, mix evenly, adjust the pH to 5, heat up, react, wash, centrifuge, and vacuum dry at 60° C. for 12 h to obtain modified white carbon black; Step 2, mix carboxymethyl cellulose and deionized water evenly, then add acrylamide and glycidyl methacrylate, stir and mix, introduce nitrogen, add a crosslinking agent and an initiator in a nitrogen atmosphere, stir and mix, react, wash after the reaction, and vacuum dry at 60° C. for 6 hours to obtain epoxy-modified carboxymethyl cellulose; Step 3, the epoxy-modified carboxymethyl cellulose, the alkenyl-terminated epoxy polyether and ethylenediamine are mixed evenly, heated to reflux, reacted, and after the reaction is completed, filtered, washed, and vacuum dried at 60° C. for 12 hours to obtain polyether-modified carboxymethyl cellulose; Step 4: mixing hydrogen-containing silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid, heating and reacting, and obtaining a modified organosilicon defoamer after the reaction is completed; In the step 2, the mass ratio of carboxymethyl cellulose, deionized water, acrylamide, glycidyl methacrylate, crosslinking agent and initiator is 100:3200-3500:12-15:38-55:0.1-0.2:3-6, the reaction temperature is 75-85°C, and the reaction time is 1-2h; In the step 3, the mass ratio of epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether and ethylenediamine is 100:118-140:185-235; The reaction temperature in step 3 is 85-95°C and the reaction time is 12-18h; In the step 4, the mass ratio of hydrogen silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid is 100:18-25:3-7:0.2-0.5; The reaction temperature in step 4 is 90-150° C., and the reaction time is 10-15 hours.

2. The method for preparing a modified organosilicon defoamer according to claim 1, characterized in that: In the step 1, the mass ratio of white carbon black, ethanol solution, 1H,1H,2H,2H-perfluorooctyltriethylsilane and γ-(methacryloyloxy)propyltrimethoxysilane is 100:3500-4200:8-14:25-42.

3. The method for preparing a modified organosilicon defoamer according to claim 1, characterized in that: The reaction temperature in step 1 is 75-85° C., and the reaction time is 30-36 h.

4. The method for preparing a modified organosilicon defoamer according to claim 1, characterized in that: In the step 2, the crosslinking agent is N,N'-methylenebisacrylamide, and the initiator is ammonium persulfate.

5. A modified organosilicon defoamer prepared by the method for preparing a modified organosilicon defoamer according to any one of claims 1 to 4.

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