Modified organic silicon defoaming agent and preparation method thereof

Abstract

The invention relates to the technical field of defoaming agents, and discloses a modified organic silicon defoaming agent and a preparation method thereof.The modified organic silicon defoaming agent takes hydrogen-containing silicone oil as a base material, polyether modified carboxymethyl cellulose and modified white carbon black are used for modifying the base material to obtain the modified organic silicon defoaming agent, and after the white carbon black is modified, the modified organic silicon defoaming agent is prepared. According to the present invention, the polyether modified organic silicon is uniformly and stably distributed in the system so as to improve the defoaming efficiency, the carboxymethyl cellulose has characteristics of excellent thickening property, excellent film forming property and excellent stability, can improve the consistency of the organic silicon defoaming agent, can help to form the stable film layer, can easily adhere and disperse the active component of the defoaming agent, and can improve the defoaming effect; the surface property of the modified organic silicon is improved, the modified organic silicon has better hydrophilicity and wettability, the structural stability of the silicone oil is improved, all the components have a synergistic effect, and the prepared modified organic silicon has excellent defoaming and foam inhibiting effects, meanwhile, the dispersity is good, the heat resistance and stability are improved, and the application range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of defoamers, in particular to a modified organosilicon defoamer and a preparation method thereof. Background Art

[0002] In industrial production, many processes often cause various problems due to the generation of foam, and even affect product quality. Therefore, it is of great significance to eliminate and inhibit the generation of harmful foam. In industry, harmful foam is usually eliminated by mechanical and chemical methods. Mechanical defoaming can only remove surface foam in a short time, but it is difficult to eliminate internal foam. Chemical defoaming is to add defoaming agents to the foam system to destroy and inhibit the formation of bubble wall films to achieve the purpose of breaking bubbles. There are many types of defoaming agents. Commonly used in industry include mineral oil defoaming agents, silicone defoaming agents and polyether defoaming agents. Among them, silicone defoaming agents have low surface tension and good chemical stability, and have excellent defoaming and anti-foaming effects. However, silicone defoaming agents have poor dispersibility in water and poor high temperature resistance, which affects stability, greatly limiting the application of silicone defoaming agents.

[0003] Chinese patent application CN116196658A discloses the synthesis of a defoamer with excellent defoaming performance, the defoamer includes polyether, modified nano-silica, composite emulsifier, hydrophobic particles, and solvent; the polyether includes fatty alcohol modified polyether and organosilane modified polyether, the composite emulsifier includes fatty acid sucrose ester, polyethylene glycol dilaurate, and Tween 80, the defoamer has the effects of strong defoaming performance, rapid defoaming, and long foam suppression time, but the modified nano-silica and hydrophobic particle white carbon black have poor dispersibility, which affects the overall performance of the defoamer. Chinese patent application CN103830938A discloses a preparation method of an organosilicon defoamer, the organosilicon defoamer is a stable emulsion formed by emulsification of components such as dimethyl silicone oil and non-ionic surfactant, which has the characteristics of fast defoaming speed and strong foam suppression ability, but poor stability and high temperature resistance, easy to demulsify, float oil and precipitate at high temperature, affecting the quality and use value of the finished product, and is not conducive to promotion and use. Summary of the invention

[0004] 1. Technical issues to be resolved

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

[0006] (II) Technical solution

[0007] In order to achieve the above object, the present invention discloses a method for preparing a modified organosilicon defoamer, comprising the following steps:

[0008] Step 1, ultrasonically disperse the 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 value of the solution to 5 with acetic acid, heat up, react, and after the reaction is completed, wash with anhydrous ethanol, centrifuge, and vacuum dry at 60°C for 12 hours to obtain modified white carbon black;

[0009] 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, and after the reaction is completed, wash with deionized water and anhydrous ethanol, and vacuum dry at 60° C. for 6 hours to obtain epoxy-modified carboxymethyl cellulose;

[0010] 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 with anhydrous ethanol and deionized water, and vacuum dried at 60° C. for 12 h to obtain polyether-modified carboxymethyl cellulose;

[0011] Step 4: Mix the hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid, heat and react, and after the reaction is completed, obtain a modified organosilicon defoamer.

[0012] Preferably, in 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.

[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 concentration of acetic acid in step 1 is 0.1 mol / L.

[0016] Preferably, in 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.

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

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

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

[0020] Preferably, the reaction temperature in step 3 is 85-95° C., and the reaction time is 12-18 h.

[0021] Preferably, in step 4, the mass ratio of hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid is 100:18-25:3-7:0.2-0.5.

[0022] Preferably, the reaction temperature in step 4 is 90-150° C., and the reaction time is 10-15 h.

[0023] A modified organosilicon defoamer prepared by the modified organosilicon defoamer preparation method.

[0024] (III) Beneficial technical effects

[0025] (1) In the present invention, 1H,1H,2H,2H-perfluorooctyl triethylsilane and γ-(methacryloyloxy)propyl trimethoxysilane are used to modify white carbon black, and fluorine atoms, long-chain alkanes, alkenyl groups and silanes are introduced on the surface of white carbon black to obtain modified white carbon black. Carboxymethyl cellulose, acrylamide and glycidyl methacrylate are polymerized under the action of a crosslinking agent and an initiator, and epoxy groups are introduced on 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 ethylenediamine to obtain polyether-modified carboxymethyl cellulose, and alkenyl groups and polyethers are introduced on carboxymethyl cellulose. The polyether-modified carboxymethyl cellulose and the alkenyl groups on the modified white carbon black undergo an addition reaction with hydrogen-containing silicone oil under the catalysis of chloroplatinic acid to obtain a modified silicone defoamer.

[0026] (2) In the present invention, white carbon black is introduced into the defoamer, and a large number of fluorine atoms and alkyl long chains are introduced on the surface of white carbon black. The modified white carbon black has excellent hydrophobicity, can reduce the association degree of white carbon black in the water system, and has excellent defoaming effect. White carbon black can effectively adsorb bubbles due to its small particle size, large specific surface area, high surface energy, and three-dimensional network structure, causing the bubbles to burst under the action of the low surface force of silicone oil. Furthermore, after the white carbon black is modified, it can be evenly and stably distributed in the system, thereby greatly improving the defoaming efficiency. Carboxymethyl cellulose has excellent thickening, film-forming and stability properties, can improve the consistency of the organosilicon defoamer system, help form a stable film layer, and help adhere and disperse the active ingredients of the defoamer, thereby improving the defoaming effect and also improving the stability of the system. Hydrogen-containing silicone oil can be used for defoaming in both water systems and oil systems, and has a wide range of applications. The surface tension of hydrogen-containing silicone oil is low, which makes it more effective in reducing the surface tension of the foaming system, effectively breaking the foam that has been generated, preventing the formation of foam, and playing a defoaming role. At the same time, it can also inhibit the generation of foam and reduce the foam in the system. Hydrogen-containing silicone oil has high heat resistance and can maintain stable performance over 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 to prevent them from falling off or unevenly dispersed during use. Carboxymethyl cellulose can also protect the active ingredients of the defoamer from interference from the external environment and extend its service life. The introduction of polyether on carboxymethyl cellulose not only introduces reactive groups for the next reaction, but also improves the surface properties of the polyether-modified silicone, which has better hydrophilicity and wettability. The polyether-modified silicone has strong surface activity and can quickly reduce the tension of the liquid surface, making the foam easier to break and improving the defoaming efficiency. At the same time, it 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 white carbon black and the hydrogen-containing silicone oil in the present invention, the structural stability of the silicone is improved, and it is not easy to react chemically with other substances. The performance can be kept unchanged under different chemical environments, thereby ensuring the durability of the defoaming effect. The various components in the prepared modified silicone defoamer synergize, have excellent defoaming and anti-foaming effects, good dispersibility, improved heat resistance and stability, and a wide range of applications. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] A method for preparing a modified organosilicon defoamer comprises the following steps:

[0032] Step 1, ultrasonically disperse the white carbon black in an ethanol solution, wherein the ethanol solution is a 75% ethanol aqueous solution, and after uniform dispersion, add 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane and γ-(methacryloyloxy) propyl trimethoxy silane, wherein the mass ratio of white carbon black, ethanol solution, 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane, and γ-(methacryloyloxy) propyl trimethoxy silane is 100:3500:8:25, mix evenly, use acetic acid to adjust the solution pH to 5, the acetic acid concentration is 0.1 mol / L, heat, react at 75°C, the reaction time is 36h, after the reaction is completed, wash with anhydrous ethanol, centrifuge, and vacuum dry at 60°C for 12h to obtain modified white carbon black;

[0033] Step 2, mix carboxymethyl cellulose and deionized water evenly, then add acrylamide and glycidyl methacrylate, stir and mix, introduce nitrogen, add N,N'-methylenebisacrylamide and ammonium persulfate in a nitrogen atmosphere, wherein 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 and mix, react at 75°C, the reaction time is 2h, after the reaction is completed, wash with deionized water and anhydrous ethanol, and vacuum dry at 60°C for 6h to obtain epoxy-modified carboxymethyl cellulose;

[0034] Step 3, epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether and ethylenediamine in a mass ratio of 100:118:185 are mixed evenly, heated to reflux, reacted at 85°C for 18 hours, and after the reaction is completed, filtered, washed with anhydrous ethanol and deionized water, and vacuum dried at 60°C for 12 hours to obtain polyether-modified carboxymethyl cellulose;

[0035] Step 4: Mix hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid in a mass ratio of 100:18:3:0.2, heat, and react at 90° C. for 15 hours. After the reaction is completed, a modified silicone defoamer is obtained.

[0036] Example 2

[0037] A method for preparing a modified organosilicon defoamer comprises the following steps:

[0038] Step 1, ultrasonically disperse the white carbon black in an ethanol solution, wherein the ethanol solution is a 75% ethanol aqueous solution, and after uniform dispersion, add 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane and γ-(methacryloyloxy) propyl trimethoxy silane, wherein the mass ratio of white carbon black, ethanol solution, 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane, and γ-(methacryloyloxy) propyl trimethoxy silane is 100:4000:12:32, mix evenly, use acetic acid to adjust the solution pH to 5, the acetic acid concentration is 0.1 mol / L, heat, react at 80°C, the reaction time is 32h, after the reaction is completed, wash with anhydrous ethanol, centrifuge, and vacuum dry at 60°C for 12h to obtain modified white carbon black;

[0039] Step 2, mix carboxymethyl cellulose and deionized water evenly, then add acrylamide and glycidyl methacrylate, stir and mix, introduce nitrogen, add N,N'-methylenebisacrylamide and ammonium persulfate in a nitrogen atmosphere, wherein 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 and mix, react at 80°C, the reaction time is 1.5h, after the reaction is completed, wash with deionized water and anhydrous ethanol, and vacuum dry at 60°C for 6h to obtain epoxy-modified carboxymethyl cellulose;

[0040] Step 3, epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether and ethylenediamine in a mass ratio of 100:125:205 are mixed evenly, heated to reflux, reacted at 90°C for 14 hours, and after the reaction is completed, filtered, washed with anhydrous ethanol and deionized water, and vacuum dried at 60°C for 12 hours to obtain polyether-modified carboxymethyl cellulose;

[0041] Step 4: Mix hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid in a mass ratio of 100:21:4:0.3, heat, and react at 105° C. for 12 hours. After the reaction is completed, a modified silicone defoamer is obtained.

[0042] Example 3

[0043] A method for preparing a modified organosilicon defoamer comprises the following steps:

[0044] Step 1, mix carboxymethyl cellulose and deionized water evenly, then add acrylamide and glycidyl methacrylate, stir and mix, introduce nitrogen, add N,N'-methylenebisacrylamide and ammonium persulfate in a nitrogen atmosphere, wherein 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, react at 80°C, the reaction time is 1.5h, after the reaction is completed, wash with deionized water and anhydrous ethanol, and vacuum dry at 60°C for 6h to obtain epoxy-modified carboxymethyl cellulose;

[0045] Step 2: Evenly mix epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether and ethylenediamine in a mass ratio of 100:135:225, heat to reflux, react at 90°C for 16 hours, and after the reaction, filter, wash with anhydrous ethanol and deionized water, and vacuum dry at 60°C for 12 hours to obtain polyether-modified carboxymethyl cellulose;

[0046] Step 3: Mix hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid in a mass ratio of 100:21:4:0.3, heat, and react at 105° C. for 12 hours. After the reaction is completed, a modified silicone defoamer is obtained.

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

[0048] Example 4

[0049] A method for preparing a modified organosilicon defoamer comprises the following steps:

[0050] Step 1: Mix hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid in a mass ratio of 100:24:6:0.4, heat, and react at 135° C. for 14 hours. After the reaction is completed, a modified silicone defoamer is obtained.

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

[0052] Example 5

[0053] A method for preparing a modified organosilicon defoamer comprises the following steps:

[0054] Step 1, ultrasonically disperse white carbon black in an ethanol solution, wherein the ethanol solution is a 75% ethanol aqueous solution, after uniform dispersion, add 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane and γ-(methacryloyloxy) propyl trimethoxy silane, wherein the mass ratio of white carbon black, ethanol solution, 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane, and γ-(methacryloyloxy) propyl trimethoxy silane is 100:4200:14:42, mix evenly, use acetic acid to adjust the solution pH to 5, the acetic acid concentration is 0.1 mol / L, heat up, react at 85°C, the reaction time is 30h, after the reaction is completed, wash with anhydrous ethanol, centrifuge, and vacuum dry at 60°C for 12h to obtain modified white carbon black;

[0055] Step 2, mix carboxymethyl cellulose and deionized water evenly, then add acrylamide and glycidyl methacrylate, stir and mix, introduce nitrogen, add N,N'-methylenebisacrylamide and ammonium persulfate in a nitrogen atmosphere, wherein 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, react at 85°C, the reaction time is 1h, after the reaction is completed, wash with deionized water and anhydrous ethanol, and vacuum dry at 60°C for 6h to obtain epoxy-modified carboxymethyl cellulose;

[0056] Step 3, epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether and ethylenediamine in a mass ratio of 100:140:235 are mixed evenly, heated to reflux, reacted at 95°C for 12 hours, and after the reaction is completed, filtered, washed with anhydrous ethanol and deionized water, and vacuum dried at 60°C for 12 hours to obtain polyether-modified carboxymethyl cellulose;

[0057] Step 4: Mix hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid in a mass ratio of 100:25:7:0.5, heat, and react at 150° C. for 10 hours. After the reaction is completed, a modified silicone defoamer is obtained.

[0058] Comparative Example 1

[0059] A method for preparing an organosilicon defoamer comprises the following steps:

[0060] Step 1, mix carboxymethyl cellulose and deionized water evenly, then add acrylamide and glycidyl methacrylate, stir and mix, introduce nitrogen, add N,N'-methylenebisacrylamide and ammonium persulfate in a nitrogen atmosphere, wherein 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, react at 80°C, the reaction time is 1.5h, after the reaction is completed, wash with deionized water and anhydrous ethanol, and vacuum dry at 60°C for 6h to obtain epoxy-modified carboxymethyl cellulose;

[0061] Step 2: Evenly mix epoxy-modified carboxymethyl cellulose, alkenyl-terminated epoxy polyether and ethylenediamine in a mass ratio of 100:135:225, heat to reflux, react at 90°C for 16 hours, and after the reaction, filter, wash with anhydrous ethanol and deionized water, and vacuum dry at 60°C for 12 hours to obtain polyether-modified carboxymethyl cellulose;

[0062] Step 3: Mix hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, white carbon black and chloroplatinic acid in a mass ratio of 100:24:6:0.4, heat, and react at 135° C. for 14 hours. After the reaction is completed, a silicone defoamer is obtained.

[0063] Comparative Example 2

[0064] A method for preparing an organosilicon defoamer comprises the following steps:

[0065] Step 1, ultrasonically disperse the white carbon black in an ethanol solution, wherein the ethanol solution is a 75% ethanol aqueous solution, and after uniform dispersion, add 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane and γ-(methacryloyloxy) propyl trimethoxy silane, wherein the mass ratio of white carbon black, ethanol solution, 1H, 1H, 2H, 2H-perfluorooctyl triethyl silane, and γ-(methacryloyloxy) propyl trimethoxy silane is 100:4000:12:32, mix evenly, use acetic acid to adjust the solution pH to 5, the acetic acid concentration is 0.1 mol / L, heat, react at 80°C, the reaction time is 32h, after the reaction is completed, wash with anhydrous ethanol, centrifuge, and vacuum dry at 60°C for 12h to obtain modified white carbon black;

[0066] Step 2: Mix hydrogenated silicone oil, carboxymethyl cellulose, olefin-terminated epoxy polyether, modified silica and chloroplatinic acid in a mass ratio of 100:10:14:6:0.4, heat, and react at 135° C. for 14 hours. After the reaction is completed, a silicone defoamer is obtained.

[0067] Comparative Example 3

[0068] A method for preparing an organosilicon defoamer comprises the following steps:

[0069] Step 1: Mix hydrogenated silicone oil, carboxymethyl cellulose, olefin-terminated epoxy polyether, white carbon black and chloroplatinic acid in a mass ratio of 100:10:14:6:0.4, heat, and react at 135° C. for 14 hours. After the reaction is completed, a silicone defoamer is obtained.

[0070] The white carbon black in the embodiments and comparative examples of the present invention is fumed white carbon black with a particle size of 7-40 nm, purchased from Guangzhou Jibisheng Technology Co., Ltd., carboxymethyl cellulose was purchased from Chengdu Kelon Chemical Reagent Co., Ltd., and alkenyl-terminated epoxy polyether was purchased from Hangzhou Diweilai Trading Co., Ltd.; hydrogen-containing silicone oil was purchased from Tianjin Yimei Fine Chemical Factory (hydrogen group mass fraction 0.2-1.0%, viscosity at 25°C 10-30 mPa·s); other undisclosed reagents are all commercially available.

[0071] The organosilicon defoamers prepared in Examples 1-5 and Comparative Examples 1-3 were tested accordingly, and the test methods and test results are as follows:

[0072] (1) Defoaming performance test: 50 g of the foaming liquid was weighed into a 100 mL stoppered measuring cylinder, and 0.05 g of the defoaming agent prepared in Examples 1-5 and Comparative Examples 1-3 was added respectively. The temperature was kept constant at 25° C. and 80° C. in a water bath, respectively. The bottle was covered with a stopper, and the measuring cylinder was vertically shaken up and down 10 times at a frequency of 2 times / s and a swing amplitude of 30-35 cm. The cylinder was left to stand and a stopwatch was used to record the time taken for the foam to disappear until the liquid surface appeared.

[0073] (2) Antifoaming performance test: A lubricating oil foam characteristic tester that meets the test requirements of GB / T 12579 was used, and the constant temperature water bath temperature of the instrument was set to 25°C and 80°C, respectively, and the test air flow rate was 100 mL / min. 100 g of the foaming liquid was weighed, and 0.1 g of the defoaming agent prepared in Examples 1-5 and Comparative Examples 1-3 was weighed, added to the foaming liquid, stirred evenly, and then poured into a clean bubbler measuring cylinder, and the temperature was kept constant at 25°C and 80°C, respectively. The flow pump was turned on and the test was started. The foam volume (mL) after 30 minutes of air blowing was recorded. The antifoaming performance was represented by the foam volume corresponding to 30 minutes of air blowing;

[0074] (3) Stability test: 15 mL of the defoamers prepared in Examples 1-5 and Comparative Examples 1-3 were respectively taken into centrifuge tubes and centrifuged in a high-speed centrifuge at a speed of 3000 r / min. The centrifuge was stopped every 5 minutes for observation, and centrifuged continuously for 30 minutes to observe whether stratification occurred. The defoamer stock solution was diluted 50 times with deionized water, stirred evenly with a glass rod, and allowed to stand for 48 hours to observe whether stratification or demulsification occurred. The test temperatures were 25° C. and 80° C., respectively.

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

[0076] Table 1

[0077]

[0078] According to the test results of Table 1, it can be seen that the defoamer corresponding to Examples 1-5 is continuously centrifuged for 30min without stratification, has excellent stability, and has excellent defoaming performance and foam suppression performance, rapid defoaming, good foam suppression effect, and under high temperature conditions, it can still maintain excellent comprehensive performance, indicating good heat resistance. In Comparative Example 1, white carbon black is not modified, and the silanol bond (Si-OH) on its surface is highly active, and it is easy to form hydrogen bonds with water molecules, but at the same time, its dispersibility in the water system will be limited, and its compatibility with hydrogen-containing silicone oil is poor, resulting in the defoamer being unstable in the system, easy to stratify or precipitate, affecting the defoaming performance, and the stability, defoaming performance and foam suppression performance of the defoamer are all reduced. In Comparative Example 2, carboxymethyl cellulose is not modified, and its solubility is poor. The active groups on the molecular chain may interact with other components in the system, resulting in a decrease in system stability. The alkenyl-terminated epoxy polyether and the modified white carbon black can react with the hydrogen-containing silicone oil, which affects the overall performance of the defoamer and deteriorates the comprehensive performance. In Comparative Example 3, white carbon black and carboxymethyl cellulose were not modified, and the comprehensive performance deteriorated significantly. At 25°C, the defoaming time was 14s, the antifoaming performance was 345mL, the stability was reduced, obvious stratification occurred, and it was unstable. At 80°C, the defoaming time was 15s, the antifoaming performance was 351mL, the stability was reduced, obvious stratification occurred, and it was unstable.

[0079] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that all equivalent changes and improvements made within the scope of the present invention should still fall within the scope of 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: Mix the hydrogenated silicone oil, polyether-modified carboxymethyl cellulose, modified white carbon black and chloroplatinic acid, heat and react, and after the reaction is completed, obtain a modified organosilicon defoamer.

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 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 1-2 h.

5. 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.

6. The method for preparing a modified organosilicon defoamer according to claim 1, characterized in that: In the step three, the mass ratio of epoxy-modified carboxymethyl cellulose, olefin-terminated epoxy polyether and ethylenediamine is 100:118-140:185-235.

7. The method for preparing a modified organosilicon defoamer according to claim 1, characterized in that: The reaction temperature in step 3 is 85-95° C., and the reaction time is 12-18 hours.

8. The method for preparing a modified organosilicon defoamer according to claim 1, characterized in that: 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.

9. The method for preparing a modified organosilicon defoamer according to claim 1, characterized in that: The reaction temperature in step 4 is 90-150° C., and the reaction time is 10-15 hours.

10. A modified organosilicon defoamer prepared by the method for preparing a modified organosilicon defoamer according to any one of claims 1 to 9.

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