An emulsion-type defoaming agent with excellent stability and preparation method thereof

Abstract

The invention relates to the technical field of defoamers and discloses an emulsion-type defoamer with excellent stability and a preparation method thereof. The invention comprises the following steps: modifying white carbon black and graphene to obtain a modified filler after reaction; subjecting the modified filler to an addition reaction with hydrogen-containing silicone oil to obtain a modified organic silicon; and stirring and mixing the modified organic silicon, a thickener, an emulsifier, and deionized water to obtain an emulsion-type defoamer with excellent stability. The white carbon black and the graphene in the defoamer synergistically cooperate with each other and can be uniformly dispersed in a matrix after modification to form a more stable defoaming system, thereby enhancing the stability of the product. The invention also has the advantages of simple preparation process, readily available raw materials, low cost, rapid elimination of foaming and prevention of foaming, and effective improvement of production efficiency. The invention also has good stability, is not prone to stratification, and has good dispersibility and storage stability.

Description

Technical Field

[0001] The present invention relates to the technical field of defoaming agents, in particular to an emulsion-type defoaming agent with excellent stability and a preparation method thereof. Background Art

[0002] In many industrial production processes, such as those in the food, pharmaceutical, and coatings industries, large amounts of foam are often generated due to stirring, vibration, boiling, and the addition of surfactants. The presence of foam can lead to reduced product quality and production capacity. To prevent this, defoamers are needed to suppress and eliminate foam. There are many types of defoamers, which can be roughly divided into three categories based on composition: silicone, polyether, and non-silicone. Silicones are excellent defoamers, with strong foam removal capabilities and a wide range of applications. However, traditional silicone defoamers have poor dispersibility in aqueous systems, prone to uneven dispersion, incomplete emulsification, demulsification, and oil flotation. This affects their stability, significantly limiting their application.

[0003] Emulsion-type silicone defoamers not only have strong defoaming power, but also have good anti-foaming effects, and are applicable to both non-aqueous phases and aqueous phases. However, emulsions are thermodynamically unstable systems. If the emulsification is not complete, as the storage time increases, the emulsion is prone to stratification, demulsification, and other phenomena, making it difficult to exert the excellent properties of the emulsion, thereby reducing its defoaming performance. Chinese patent CN106868935A discloses a defoamer for papermaking and a preparation method thereof. The defoamer includes modified dimethylsiloxane, modified polyoxyethylene ether, silicon dioxide, an emulsifier, a nonionic surfactant, and a thickener. It is resistant to high temperatures and strong alkalis, and can quickly defoam under high temperature and strong alkali conditions, with long-lasting anti-foaming and defoaming effects. However, the stability and uniformity of the defoamer are poor. Chinese patent application CN105289048A discloses a silicone-modified polyetherester emulsion defoamer and a preparation method thereof. Polyoxypropylene polyoxyethylene pentaerythritol ether fatty acid ester reacts with hydrogen-containing silicone oil in the presence of a catalyst to obtain a silicone-modified polyetherester. The silicone-modified polyetherester emulsion defoamer is emulsified with a composite emulsifier to obtain a silicone-modified polyetherester emulsion defoamer. The defoamer has excellent defoaming and anti-foaming properties, but the dispersion effect and stability of the emulsion defoamer are average.

[0004] Therefore, it is of great significance to develop an emulsion defoamer with good stability, defoaming and foam suppression effects. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In order to solve the above technical problems, the present invention provides an emulsion defoamer with excellent stability and a preparation method thereof. The emulsion defoamer has excellent stability as well as excellent defoaming and antifoaming capabilities.

[0007] (2) Technical solution

[0008] In order to achieve the above object, the present invention discloses a method for preparing an emulsion-type defoaming agent with excellent stability, comprising the following steps:

[0009] Step 1: ultrasonically disperse silica in an ethanol solution, adjust the pH to 3-4 with an acetic acid solution, add γ-glycidyloxypropyltrimethoxysilane, heat, mix evenly, react, cool, centrifuge, wash with anhydrous ethanol, and dry in a drying oven at 80°C for 24 hours to obtain epoxidized silica;

[0010] Step 2: ultrasonically disperse the epoxidized silica in toluene, mix well, add 9-octadecene-1,12-diol, heat, mix, react, and after the reaction is completed, filter, wash with methanol, and dry in a drying oven at 60°C for 24 hours to obtain modified silica;

[0011] Step 3: Ultrasonic dispersion of carboxylated graphene in N,N-dimethylformamide was performed. After uniform dispersion, modified silica was added, the temperature was increased, a catalyst was added, and the mixture was stirred and mixed to react. After the reaction was completed, the mixture was filtered, washed with anhydrous ethanol, and dried in a vacuum drying oven at 60° C. for 12 h to obtain a fatty alcohol-modified filler.

[0012] Step 4: mixing the hydrogenated silicone oil, the fatty alcohol modified filler and chloroplatinic acid, heating them in a nitrogen atmosphere, and reacting them to obtain modified organosilicon after the reaction is completed;

[0013] Step 5: Evenly mix the modified silicone and thickener, heat to 40-50°C, stir for 1-2 hours, add the emulsifier, stir for 15-30 minutes, then add deionized water, stir for 30-45 minutes, and cool to obtain an emulsion defoamer with excellent stability.

[0014] Preferably, in step 1, the mass ratio of white carbon black, ethanol solution, and γ-glycidyloxypropyltrimethoxysilane is 100:950-1200:12-15.

[0015] Preferably, the reaction temperature in step 1 is 55-65° C., and the reaction time is 4-6 h.

[0016] Preferably, the ethanol solution in step 1 is a 95% ethanol aqueous solution.

[0017] Preferably, in step 2, the mass ratio of epoxidized silica, toluene, and 9-octadecene-1,12-diol is 100:1200-1500:85-102.

[0018] Preferably, the reaction temperature in step 2 is 105-115° C., and the reaction time is 12-15 h.

[0019] Preferably, in step three, the mass ratio of carboxylated graphene, N,N-dimethylformamide, modified silica, and catalyst is 15-25:3500-4800:100:0.5-0.8.

[0020] Preferably, the preparation method of carboxylated graphene in step three is as follows: 40 mL of graphene oxide dispersion and 60 mL of deionized water are mixed evenly, 5.0 g of sodium hydroxide and 7.5 g of sodium chloroacetate are added, mixed for 8 hours, centrifuged at a rate of 8000 r / min, centrifuged for 5 minutes, washed, neutralized, dialyzed, and dried at 60° C. for 12 hours to obtain carboxylated graphene.

[0021] Furthermore, the graphene oxide dispersion was purchased from Beijing Carbon Century Technology Co., Ltd., model number CCTGO-204.

[0022] Preferably, the catalyst in step three is p-toluenesulfonic acid.

[0023] Preferably, the reaction temperature in step 3 is 100-110° C., and the reaction time is 5-8 h.

[0024] Preferably, in step 4, the mass ratio of hydrogenated silicone oil, fatty alcohol modified filler and chloroplatinic acid is 100:6-10:0.2-0.4.

[0025] Preferably, the reaction temperature in step 4 is 95-130° C., and the reaction time is 4-6 h.

[0026] Preferably, in step 5, the mass ratio of modified silicone, thickener, emulsifier and deionized water is 100:0.3-0.5:6-9:105-140.

[0027] Preferably, the thickener in step 5 includes one or more of carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0028] Preferably, the emulsifier in step 5 is composed of Span 80 and Tween 80 in a mass ratio of 3:2.

[0029] The invention discloses an emulsion type defoamer with excellent stability prepared by adopting the preparation method of the emulsion type defoamer with excellent stability.

[0030] (3) Beneficial technical effects

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) In the present invention, γ-glycidyloxypropyltrimethoxysilane is used to modify silica, and epoxy groups are introduced on the surface of silica to obtain epoxidized silica. The epoxidized silica reacts with some hydroxyl groups on 9-octadecene-1,12-diol, and the epoxy groups undergo ring opening, introducing a large number of hydroxyl groups to obtain modified silica. The hydroxyl groups on the modified silica react with the carboxyl groups on the carboxylated graphene under the action of a catalyst to obtain a fatty alcohol-modified filler. The alkenyl groups on the fatty alcohol-modified filler and the hydrogenated silicone oil react under the action of chloroplatinic acid as a catalyst to obtain a modified silicone. The modified silicone, thickener, and emulsifier work together and are mixed with deionized water to obtain an emulsion-type defoamer with excellent stability. The compound emulsifier enhances the balance and stability of the system and improves the overall performance of the emulsion. 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, and facilitate the adhesion and dispersion of the defoamer active ingredients, thereby improving the defoaming effect and the stability of the system. Hydrogenated silicone oil can be used for defoaming in both water-based and oil-based systems, and has a wide range of applications. Hydrogenated silicone oil has a low surface tension, which makes it more effective in reducing the surface tension of the foaming system, effectively breaking up existing foam and preventing the formation of foam, thus playing a defoaming role. It can also inhibit the generation of foam and reduce the amount of foam in the system. Hydrogenated silicone oil also has high heat resistance and can maintain stable performance over a wide temperature range.

[0033] (2) The emulsion defoamer of the present invention has the ability to quickly eliminate and prevent the generation of foam, can effectively improve production efficiency, and has good stability, is not prone to stratification, and has good dispersibility and storage stability. Due to its small particle size, large specific surface area, high surface energy, and three-dimensional network structure, white carbon black constitutes a large number of basic defoaming units, which can effectively adsorb bubbles and cause 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, which greatly improves the defoaming efficiency. At the same time, white carbon black also plays a role in thickening and anti-settling, improving the storage stability of the system. Graphene has a large specific surface area and loading sites, and can undergo physical adsorption with other substances, thereby enhancing the stability of the defoamer. Furthermore, graphene has the advantages of high temperature resistance, acid and alkali resistance, etc., which can greatly improve the comprehensive performance of the system and improve its stability. Silica and graphene work synergistically and cooperate with each other. After modification, they can be evenly dispersed in the matrix to form a more stable defoaming system, enhance the stability of the product, and further improve the defoaming and anti-foaming performance of the defoamer.

[0034] (3) After the reaction of white carbon black and graphene in the present invention, the dispersibility of white carbon black and graphene can be effectively improved, and the reaction with hydrogenated silicone oil can achieve excellent dispersibility and compatibility of the raw materials in the defoamer system. The use of long-chain fatty alcohols to modify silicone can quickly reduce the surface tension of the liquid, destroy the stability of the foam, thereby effectively eliminating the foam, and can also inhibit the regeneration of the foam for a long time. At the same time, it has better spreadability and adsorption, quickly spreads on the foam surface, and adsorbs on the gas-liquid interface of the bubbles, causing the bubbles to burst quickly. Through chemical reactions, the stability and defoaming effect of the defoamer are further enhanced. The preparation process of the emulsion defoamer is simple, the raw materials are easily available, and the cost is low. The prepared emulsion defoamer maintains good defoaming and anti-foaming properties while having the characteristics of high efficiency and stability, and has a wide range of uses. DETAILED DESCRIPTION

[0035] 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 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.

[0036] Example 1

[0037] A method for preparing an emulsion-type defoamer with excellent stability comprises the following steps:

[0038] Step 1, ultrasonically disperse silica into 95% ethanol aqueous solution, adjust the pH to 3 with acetic acid solution, and then add γ-glycidyloxypropyltrimethoxysilane, wherein the mass ratio of silica, ethanol solution, and γ-glycidyloxypropyltrimethoxysilane is 100:950:12, heat, mix evenly, react at 55°C, and react for 6 hours. After the reaction is completed, cool, centrifuge, wash with anhydrous ethanol, and dry in a drying oven at 80°C for 24 hours to obtain epoxidized silica;

[0039] Step 2: ultrasonically disperse the epoxidized silica in toluene, mix evenly, add 9-octadecene-1,12-diol, wherein the mass ratio of the epoxidized silica, toluene, and 9-octadecene-1,12-diol is 100:1200:85, heat, mix, react at 105°C, and react for 15 hours. After the reaction is completed, filter, wash with methanol, and dry in a drying oven at 60°C for 24 hours to obtain modified silica;

[0040] Step 3: ultrasonically disperse carboxylated graphene into N,N-dimethylformamide, and after uniform dispersion, add modified silica, heat, and add p-toluenesulfonic acid as a catalyst, wherein the mass ratio of carboxylated graphene, N,N-dimethylformamide, modified silica, and p-toluenesulfonic acid as a catalyst is 15:3500:100:0.5, stir and mix, react at 100°C, and react for 8 hours. After the reaction is completed, filter, wash with anhydrous ethanol, and dry in a vacuum drying oven at 60°C for 12 hours to obtain a fatty alcohol modified filler;

[0041] Step 4: Mix hydrogenated silicone oil, fatty alcohol modified filler and chloroplatinic acid in a mass ratio of 100:6:0.2, heat in a nitrogen atmosphere, and react at 95° C. for 6 hours to obtain modified organosilicon;

[0042] Step 5: Evenly mix the modified silicone and thickener carboxymethyl cellulose, heat to 40°C, stir for 2 hours, add an emulsifier consisting of Span 80 and Tween 80 in a mass ratio of 3:2, stir for 15 minutes, and then add deionized water, wherein the mass ratio of modified silicone, thickener, emulsifier, and deionized water is 100:0.3:6:105, stir for 30 minutes, and cool to obtain an emulsion-type defoamer with excellent stability.

[0043] Example 2

[0044] A method for preparing an emulsion-type defoamer with excellent stability comprises the following steps:

[0045] Step 1, ultrasonically disperse silica into 95% ethanol aqueous solution, adjust the pH to 3.5 with acetic acid solution, and then add γ-glycidyloxypropyltrimethoxysilane, wherein the mass ratio of silica, ethanol solution, and γ-glycidyloxypropyltrimethoxysilane is 100:1100:14, heat, mix evenly, react at 60°C, and react for 5 hours. After the reaction is completed, cool, centrifuge, wash with anhydrous ethanol, and dry in a drying oven at 80°C for 24 hours to obtain epoxidized silica;

[0046] Step 2: ultrasonically disperse the epoxidized silica in toluene, mix evenly, add 9-octadecene-1,12-diol, wherein the mass ratio of the epoxidized silica, toluene, and 9-octadecene-1,12-diol is 100:1400:95, heat, mix, react at 110°C, and react for 14 hours. After the reaction is completed, filter, wash with methanol, and dry in a drying oven at 60°C for 24 hours to obtain modified silica;

[0047] Step 3: ultrasonically disperse carboxylated graphene into N,N-dimethylformamide, and after uniform dispersion, add modified silica, heat, and add p-toluenesulfonic acid as a catalyst, wherein the mass ratio of carboxylated graphene, N,N-dimethylformamide, modified silica, and p-toluenesulfonic acid as a catalyst is 21:4200:100:0.7, stir and mix, react at 105°C for 6 hours, and after the reaction is completed, filter, wash with anhydrous ethanol, and dry in a vacuum drying oven at 60°C for 12 hours to obtain a fatty alcohol modified filler;

[0048] Step 4: mixing hydrogenated silicone oil, fatty alcohol modified filler and chloroplatinic acid in a mass ratio of 100:8:0.25, heating in a nitrogen atmosphere, and reacting at 105° C. for 5 hours to obtain modified organosilicon;

[0049] Step 5: Evenly mix the modified silicone and thickener carboxymethyl cellulose, heat to 45°C, stir for 1.5 hours, add an emulsifier consisting of Span 80 and Tween 80 in a mass ratio of 3:2, stir for 18 minutes, and then add deionized water, wherein the mass ratio of modified silicone, thickener, emulsifier, and deionized water is 100:0.35:7:118, stir for 35 minutes, and cool to obtain an emulsion-type defoamer with excellent stability.

[0050] Example 3

[0051] A method for preparing an emulsion-type defoamer with excellent stability comprises the following steps:

[0052] Step 1: Mix hydrogenated silicone oil, fatty alcohol modified filler and chloroplatinic acid in a mass ratio of 100:9:0.35, heat in a nitrogen atmosphere, and react at 120° C. for 5 hours to obtain modified organosilicon;

[0053] Step 2: Evenly mix the modified silicone and thickener carboxymethyl cellulose, heat to 45°C, stir for 1.5 hours, add an emulsifier consisting of Span 80 and Tween 80 in a mass ratio of 3:2, stir for 25 minutes, and then add deionized water, wherein the mass ratio of modified silicone, thickener, emulsifier, and deionized water is 100:0.45:8:130, stir for 40 minutes, and cool to obtain an emulsion-type defoamer with excellent stability.

[0054] The preparation method of the fatty alcohol modified filler is the same as the preparation method of the fatty alcohol modified filler in Example 2.

[0055] Example 4

[0056] A method for preparing an emulsion-type defoamer with excellent stability comprises the following steps:

[0057] Step 1, ultrasonically disperse silica into 95% ethanol aqueous solution, adjust the pH to 4 with acetic acid solution, and then add γ-glycidyloxypropyltrimethoxysilane, wherein the mass ratio of silica, ethanol solution, and γ-glycidyloxypropyltrimethoxysilane is 100:1200:15, heat, mix evenly, react at 65°C, and react for 4 hours. After the reaction is completed, cool, centrifuge, wash with anhydrous ethanol, and dry in a drying oven at 80°C for 24 hours to obtain epoxidized silica;

[0058] Step 2: ultrasonically disperse the epoxidized silica in toluene, mix evenly, add 9-octadecene-1,12-diol, wherein the mass ratio of the epoxidized silica, toluene, and 9-octadecene-1,12-diol is 100:1500:102, heat, mix, react at 115°C, and react for 12 hours. After the reaction is completed, filter, wash with methanol, and dry in a drying oven at 60°C for 24 hours to obtain modified silica;

[0059] Step 3: ultrasonically disperse carboxylated graphene into N,N-dimethylformamide, and after uniform dispersion, add modified silica, heat, and add p-toluenesulfonic acid as a catalyst, wherein the mass ratio of carboxylated graphene, N,N-dimethylformamide, modified silica, and p-toluenesulfonic acid as a catalyst is 25:4800:100:0.8, stir and mix, react at 110°C for 5 hours, and after the reaction is completed, filter, wash with anhydrous ethanol, and dry in a vacuum drying oven at 60°C for 12 hours to obtain a fatty alcohol modified filler;

[0060] Step 4: Mix hydrogenated silicone oil, fatty alcohol-modified filler, and chloroplatinic acid in a mass ratio of 100:10:0.4, heat in a nitrogen atmosphere, and react at 130° C. for 4 hours to obtain modified organosilicon;

[0061] Step 5: Evenly mix the modified silicone and thickener carboxymethyl cellulose, heat to 50°C, stir for 1 hour, add an emulsifier consisting of Span 80 and Tween 80 in a mass ratio of 3:2, stir for 30 minutes, and then add deionized water, wherein the mass ratio of modified silicone, thickener, emulsifier, and deionized water is 100:0.5:9:140, stir for 45 minutes, and cool to obtain an emulsion-type defoamer with excellent stability.

[0062] Comparative Example 1

[0063] A method for preparing an emulsion defoamer comprises the following steps:

[0064] Step 1, ultrasonically disperse silica into 95% ethanol aqueous solution, adjust the pH to 3.5 with acetic acid solution, and then add γ-glycidyloxypropyltrimethoxysilane, wherein the mass ratio of silica, ethanol solution, and γ-glycidyloxypropyltrimethoxysilane is 100:1100:14, heat, mix evenly, react at 60°C, and react for 5 hours. After the reaction is completed, cool, centrifuge, wash with anhydrous ethanol, and dry in a drying oven at 80°C for 24 hours to obtain epoxidized silica;

[0065] Step 2: ultrasonically disperse carboxylated graphene into N,N-dimethylformamide, and after uniform dispersion, add epoxidized silica, heat, and add p-toluenesulfonic acid as a catalyst, wherein the mass ratio of carboxylated graphene, N,N-dimethylformamide, epoxidized silica, and p-toluenesulfonic acid as a catalyst is 21:4200:100:0.7, stir and mix, react at 105°C, and react for 6 hours. After the reaction is completed, filter, wash with anhydrous ethanol, and dry in a vacuum drying oven at 60°C for 12 hours to obtain a modified filler;

[0066] Step 3: Evenly mix the hydrogenated silicone oil, modified filler, and thickener carboxymethyl cellulose, raise the temperature to 45°C, stir for 1.5 hours, add an emulsifier, the emulsifier is composed of Span 80 and Tween 80 in a mass ratio of 3:2, stir for 25 minutes, and then add deionized water, wherein the mass ratio of hydrogenated silicone oil, modified filler, thickener, emulsifier, and deionized water is 92:8:0.45:8:130, stir for 40 minutes, and cool to obtain an emulsion defoamer.

[0067] Comparative Example 2

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

[0069] Step 1, ultrasonically disperse silica into 95% ethanol aqueous solution, adjust the pH to 3.5 with acetic acid solution, and then add γ-glycidyloxypropyltrimethoxysilane, wherein the mass ratio of silica, ethanol solution, and γ-glycidyloxypropyltrimethoxysilane is 100:1100:14, heat, mix evenly, react at 60°C, and react for 5 hours. After the reaction is completed, cool, centrifuge, wash with anhydrous ethanol, and dry in a drying oven at 80°C for 24 hours to obtain epoxidized silica;

[0070] Step 2: ultrasonically disperse the epoxidized silica in toluene, mix evenly, add 9-octadecene-1,12-diol, wherein the mass ratio of the epoxidized silica, toluene, and 9-octadecene-1,12-diol is 100:1400:95, heat, mix, react at 110°C, and react for 14 hours. After the reaction is completed, filter, wash with methanol, and dry in a drying oven at 60°C for 24 hours to obtain modified silica;

[0071] Step 3: ultrasonically disperse carboxylated graphene into N,N-dimethylformamide, and after uniform dispersion, add modified silica, heat, and add p-toluenesulfonic acid as a catalyst, wherein the mass ratio of carboxylated graphene, N,N-dimethylformamide, modified silica, and p-toluenesulfonic acid as a catalyst is 21:4200:100:0.7, stir and mix, react at 105°C for 6 hours, and after the reaction is completed, filter, wash with anhydrous ethanol, and dry in a vacuum drying oven at 60°C for 12 hours to obtain a fatty alcohol modified filler;

[0072] Step 4: Evenly mix the hydrogenated silicone oil, fatty alcohol-modified filler and thickener carboxymethyl cellulose, heat to 45°C, stir for 1.5h, add an emulsifier, the emulsifier is composed of Span 80 and Tween 80 in a mass ratio of 3:2, stir for 25min, and then add deionized water, wherein the mass ratio of hydrogenated silicone oil, fatty alcohol-modified filler, thickener, emulsifier and deionized water is 92:8:0.45:8:130, stir for 40min, and cool to obtain an emulsion defoamer.

[0073] Comparative Example 3

[0074] A method for preparing an emulsion defoamer comprises the following steps:

[0075] Step 1, ultrasonically disperse silica into 95% ethanol aqueous solution, adjust the pH to 3.5 with acetic acid solution, and then add γ-glycidyloxypropyltrimethoxysilane, wherein the mass ratio of silica, ethanol solution, and γ-glycidyloxypropyltrimethoxysilane is 100:1100:14, heat, mix evenly, react at 60°C, and react for 5 hours. After the reaction is completed, cool, centrifuge, wash with anhydrous ethanol, and dry in a drying oven at 80°C for 24 hours to obtain epoxidized silica;

[0076] Step 2: Mix the hydrogenated silicone oil, epoxidized silica, carboxylated graphene and thickener carboxymethyl cellulose evenly, heat to 45 ° C, stir for 1.5 hours, add an emulsifier, the emulsifier is composed of Span 80 and Tween 80 in a mass ratio of 3:2, stir for 25 minutes, and then add deionized water, wherein the mass ratio of hydrogenated silicone oil, epoxidized silica, carboxylated graphene, thickener, emulsifier and deionized water is 92:6.6:1.4:0.45:8:130, stir for 40 minutes, and cool to obtain an emulsion defoamer.

[0077] Comparative Example 4

[0078] A method for preparing an emulsion defoamer comprises the following steps:

[0079] Step 1: Evenly mix hydrogenated silicone oil, white carbon black, graphene oxide and thickener carboxymethyl cellulose, heat to 45 ° C, stir for 1.5 hours, add emulsifier, the emulsifier is composed of Span 80 and Tween 80 in a mass ratio of 3:2, stir for 25 minutes, and then add deionized water, wherein the mass ratio of hydrogenated silicone oil, white carbon black, graphene oxide, thickener, emulsifier and deionized water is 92:6.6:1.4:0.45:8:130, stir for 40 minutes, and cool to obtain an emulsion defoamer.

[0080] The silica in the examples and comparative examples of the present invention is fumed silica with a particle size of 7-40 nm, purchased from Guangzhou Jibisheng Technology Co., Ltd., hydrogenated silicone oil was purchased from Tianjin Yimei Fine Chemical Factory (hydrogen group mass fraction 0.2-1.0%, viscosity 10-30 mPa·s at 25°C), and the CAS number of 9-octadecene-1,12-diol is 1577-55-5. Other undisclosed reagents are commercially available.

[0081] The emulsion defoamers prepared in Examples 1-4 and Comparative Examples 1-4 were tested accordingly. The test methods and test results are shown below:

[0082] (1) Defoaming performance test: The test standard adopts GB / T26527-2011, and the defoaming performance test condition is to shake the measuring cylinder vertically up and down 10 times;

[0083] (2) Foam suppression performance test: A lubricating oil foam characteristic tester that meets the test requirements of GB / T 12579 was used. The constant temperature water bath temperature of the instrument was set to 25°C and 80°C, and the test air flow rate was 100 mL / min. 100 g of foaming liquid was weighed, and 0.1 g of the defoaming agent prepared in Examples 1-4 and Comparative Examples 1-4 was weighed, added to the foaming liquid, stirred evenly, and then poured into a clean bubbler measuring cylinder. 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 foam suppression performance was expressed by the foam volume corresponding to 30 minutes of air blowing.

[0084] (3) Stability test: 15 mL of each emulsion defoamer prepared in Examples 1-4 and Comparative Examples 1-4 were placed in a centrifuge tube and centrifuged at 3000 rpm in a high-speed centrifuge for 30 minutes to observe its stability.

[0085] The above test results are shown in Table 1:

[0086] Table 1

[0087] Test items Defoaming performance(s) Foam suppression performance (mL) stability Example 1 8.6 321 Unstratified Example 2 6.9 297 Unstratified Example 3 5.7 285 Unstratified Example 4 7.3 310 Unstratified Comparative Example 1 14.1 345 More obvious stratification Comparative Example 2 11.7 332 Slight delamination Comparative Example 3 15.2 353 More obvious stratification Comparative Example 4 16.4 362 Obvious stratification

[0088] According to the test result of Table 1, it can be seen that the defoamer corresponding to Example 1-4 is continuously centrifuged for 30min without stratification, has excellent stability, and defoaming performance and foam suppression performance are excellent, defoaming is rapid, and foam suppression effect is good. Fatty alcohol is not introduced in Comparative Example 1, epoxidized white carbon black and carboxylated graphene are directly mixed to obtain modified filler, then hydrogenated silicone oil, modified filler, thickener, emulsifier are mixed, the dispersibility variation between raw materials, and comprehensive property is greatly reduced, poor stability, and more obvious stratification occurs, and defoaming performance and foam suppression performance are reduced, and defoaming time is 14.1s, and foam suppression performance is 345mL. In Comparative Example 2, hydrogenated silicone oil, fatty alcohol modified filler are directly mixed, and comprehensive property is reduced, and defoaming time is 11.7s, and foam suppression performance is 332mL, and stability is reduced, and slight stratification occurs. In Comparative Example 3, epoxidized silica and carboxylated graphene were used instead of fatty alcohol-modified fillers. Hydrogenated silicone oil was mixed and emulsified with epoxidized silica, carboxylated graphene, a thickener, an emulsifier, and deionized water. This resulted in poor defoaming and antifoaming performance, with significant delamination. In Comparative Example 4, silica and graphene oxide were not modified and were added directly to the defoamer system. This significantly reduced overall performance, with a defoaming time of 16.4 seconds, antifoaming performance of 362 mL, and significant delamination.

[0089] 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 these 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 an emulsion-type defoamer with excellent stability, characterized in that: The steps include: Step 1: ultrasonically disperse silica in an ethanol solution, adjust the pH to 3-4, add γ-glycidyloxypropyltrimethoxysilane, heat, mix evenly, react, cool after the reaction, centrifuge, wash, and dry in a drying oven at 80°C for 24 hours to obtain epoxidized silica; Step 2: ultrasonically disperse the epoxidized silica in toluene, mix well, add 9-octadecene-1,12-diol, heat, mix, react, and after the reaction is completed, filter, wash, and dry in a drying oven at 60°C for 24 hours to obtain modified silica; Step 3: Ultrasonic dispersion of carboxylated graphene in N,N-dimethylformamide was performed. After uniform dispersion, modified silica was added, the temperature was increased, a catalyst was added, and the mixture was stirred and mixed to react. After the reaction was completed, the mixture was filtered, washed, and dried in a vacuum drying oven at 60° C. for 12 h to obtain a fatty alcohol-modified filler. Step 4: mixing the hydrogenated silicone oil, the fatty alcohol modified filler and chloroplatinic acid, heating them in a nitrogen atmosphere, and reacting them to obtain modified organosilicon after the reaction is completed; Step 5: Evenly mix the modified silicone and thickener, heat to 40-50°C, stir for 1-2 hours, add the emulsifier, stir for 15-30 minutes, then add deionized water, stir for 30-45 minutes, and cool to obtain an emulsion defoamer with excellent stability; In the step 5, the thickener is carboxymethyl cellulose; In the step 5, the emulsifier is composed of Span 80 and Tween 80 in a mass ratio of 3:

2.

2. The method for preparing an emulsion-type defoamer with excellent stability according to claim 1, wherein: In the step 1, the mass ratio of white carbon black, ethanol solution, and γ-glycidyloxypropyltrimethoxysilane is 100:950-1200:12-15, the reaction temperature is 55-65° C., and the reaction time is 4-6 hours.

3. The method for preparing an emulsion-type defoamer with excellent stability according to claim 1, wherein: In the step 2, the mass ratio of epoxidized silica, toluene, and 9-octadecene-1,12-diol is 100:1200-1500:85-102.

4. The method for preparing an emulsion-type defoamer with excellent stability according to claim 1, wherein: The reaction temperature in step 2 is 105-115° C., and the reaction time is 12-15 h.

5. The method for preparing an emulsion-type defoamer with excellent stability according to claim 1, wherein: In the step three, the mass ratio of carboxylated graphene, N,N-dimethylformamide, modified silica, and catalyst is 15-25:3500-4800:100:0.5-0.8, the reaction temperature is 100-110° C., and the reaction time is 5-8 hours.

6. The method for preparing an emulsion-type defoamer with excellent stability according to claim 1, wherein: In the step 4, the mass ratio of hydrogenated silicone oil, fatty alcohol modified filler and chloroplatinic acid is 100:6-10:0.2-0.4, the reaction temperature is 95-130° C., and the reaction time is 4-6 hours.

7. The method for preparing an emulsion-type defoamer with excellent stability according to claim 1, wherein: In the step 5, the mass ratio of the modified silicone, thickener, emulsifier and deionized water is 100:0.3-0.5:6-9:105-140.

8. An emulsion-type defoamer with excellent stability prepared by the method for preparing an emulsion-type defoamer with excellent stability according to any one of claims 1 to 7.