High-temperature-resistant environment-friendly defoaming agent and preparation method thereof

Abstract

The present application relates to the field of high-temperature-resistant environment-friendly defoaming agent, and particularly relates to a high-temperature-resistant environment-friendly defoaming agent and a preparation method thereof, which are used to solve the technical problems of poor high-temperature resistance, high-temperature easy emulsion breaking and layering, weak defoaming and bubble suppressing effect and insufficient environmental protection of traditional organic silicon defoaming agent; the high-temperature-resistant environment-friendly defoaming agent is prepared by mixing phenyl-polyether-epoxy three-modified polysiloxane and modified hydrophobic fumed silica to form high-temperature silicon paste, then mixing composite emulsifier, glycerol and deionized water to form water phase, dropping the high-temperature silicon paste into the water phase to obtain pre-emulsion, adding xanthan gum to thicken and stabilize the pre-emulsion, and filtering to obtain the high-temperature-resistant environment-friendly defoaming agent; the defoaming agent has the advantages of high-temperature resistance, strong stability, long-lasting defoaming and bubble suppressing, environmental protection and no APEO, and has wide application range and is not easy to emulsion break and oil float.

Description

Technical Field

[0001] This invention relates to the field of high-temperature resistant and environmentally friendly defoamers, specifically to a high-temperature resistant and environmentally friendly defoamer and its preparation method. Background Technology

[0002] Defoamers are key functional additives in industrial production, widely used in chemical, printing and dyeing, and wastewater treatment industries. Traditional silicone defoamers are mostly based on polydimethylsiloxane, which has poor high-temperature resistance and is prone to demulsification, layering, and a sharp drop in defoaming efficiency in high-temperature, high-shear systems. Simple polyether or phenyl-modified silicone oils cannot simultaneously achieve compatibility, foam suppression, and high-temperature stability. Ordinary hydrophobic fumed silica is prone to agglomeration and has poor compatibility with the matrix, further limiting the long-term performance of the product.

[0003] With increasingly stringent environmental protection requirements, traditional defoamers containing volatile organic compounds and recalcitrant components can no longer meet the demands of green production. Currently, there is a lack of water-based silicone defoamers on the market that combine rapid defoaming, long-lasting foam suppression, high-temperature stability, and environmental friendliness, making them unsuitable for industrial applications under harsh high-temperature conditions. Therefore, developing a structurally stable, high-temperature resistant, and environmentally friendly high-efficiency defoamer has significant practical value and market potential. Summary of the Invention

[0004] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a high-temperature resistant and environmentally friendly defoamer and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] In a first aspect, this application provides a high-temperature resistant and environmentally friendly defoamer, comprising the following components in parts by weight:

[0007] 30-40 parts of phenyl-polyether-epoxy tri-modified polysiloxane, 1.5-3.0 parts of modified hydrophobic fumed silica, 4-7 parts of composite emulsifier, 1-2 parts of glycerol, 0.1-0.4 parts of xanthan gum, and 40-60 parts of deionized water;

[0008] The phenyl-polyether-epoxy tri-modified polysiloxane is prepared by the following steps:

[0009] Step a1: Octamethylcyclotetrasiloxane, D4Hcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, octaphenylcyclotetrasiloxane, and trifluoromethanesulfonic acid were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at a temperature of 25-30℃ and a stirring rate of 300-400 r / min for 24-26 h. After the reaction was completed, anhydrous sodium bicarbonate was added and stirred for 60-65 min. The mixture was then filtered, and the filtrate was evaporated by rotary evaporation. The filtrate was then placed in a vacuum drying oven and dried at a temperature of 80-85℃ for 6-7 h to obtain a phenyl-modified hydrogen-containing polysiloxane intermediate.

[0010] Step a2: Add ethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, Karstedt catalyst, and toluene to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen for protection and stir for 15-20 min at 80-85℃ and a stirring rate of 300-400 r / min. Add the phenyl-modified hydrogen-containing polysiloxane intermediate-toluene solution dropwise to the three-necked flask using a constant pressure dropping funnel, completing the addition within 90-100 min. Then heat to 100℃ and continue the reaction for 5-7 h. After the reaction is complete, cool to room temperature and then perform rotary evaporation. After extraction with n-hexane 3-4 times, the organic phase is rotary evaporated again and then placed in a vacuum drying oven and dried at 80-85℃ for 4-5 h to obtain phenyl-polyether dual-modified polysiloxane.

[0011] Step a3: Add phenyl-polyether-modified polysiloxane, epichlorohydrin, and tetrabutylammonium bromide to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen for protection and stir for 6-7 hours at 80-85℃ and a stirring rate of 300-400 r / min. Then cool to room temperature, add sodium hydroxide solution dropwise, and continue stirring for 4-5 hours at 50-55℃. After the reaction is complete, extract with dichloromethane, wash the organic phase 3-4 times with deionized water, dry with anhydrous magnesium sulfate, filter, concentrate the filtrate by rotary evaporation, and then place it in a vacuum drying oven at 80-85℃ for 6-7 hours to obtain phenyl-polyether-epoxy trimodified polysiloxane.

[0012] In a preferred embodiment of the present invention, the ratio of the amounts of octamethylcyclotetrasiloxane, D4H-cyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, octaphenylcyclotetrasiloxane, trifluoromethanesulfonic acid, and anhydrous sodium bicarbonate in step a1 is 25-31g: 15.0-18.8g: 1.4-1.8g: 1.95-2.43g: 0.08-0.10g: 2.2-2.8g.

[0013] In a preferred embodiment of the present invention, the ratio of the amount of ethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, toluene, and phenyl-modified hydrogen-containing polysiloxane intermediate-toluene solution in step a2 is 22-24g: 27-29g: 14.4-15.7mL: 14.4-15.7mL.

[0014] In a preferred embodiment of the present invention, the amount of Karstedt catalyst used in step a2 is 9-11 ppm of the total system mass.

[0015] In a preferred embodiment of the present invention, the phenyl-modified hydrogen-containing polysiloxane intermediate-toluene solution in step a2 is a solution prepared by mixing phenyl-modified hydrogen-containing polysiloxane intermediate and toluene in a ratio of 13g:14.4mL.

[0016] In a preferred embodiment of the present invention, the polyethylene glycol monoallyl ether in step a2 is of type APEG-1000.

[0017] In a preferred embodiment of the present invention, the ratio of the amount of phenyl-polyether bis-modified polysiloxane, epichlorohydrin, tetrabutylammonium bromide and sodium hydroxide solution in step a3 is 21-23g: 26-29g: 2.9-3.2g: 5-6mL.

[0018] In a preferred embodiment of the present invention, the sodium hydroxide solution in step a3 has a mass fraction of 40%.

[0019] The modified hydrophobic fumed silica is prepared by the following steps:

[0020] Hydrophobic fumed silica was added to toluene and placed in an ultrasonic disperser. The mixture was ultrasonically dispersed for 30-32 minutes at a power of 200-300 W and a stirring speed of 500-800 rpm. Nitrogen gas was then introduced and the mixture was purged at a rate of 50-80 mL / min for 20-22 minutes. The resulting solution was then transferred to a three-necked flask and added dropwise through a constant-pressure dropping funnel at a temperature of 75-80℃ and a stirring speed of 700-800 rpm. Glycidyl etheroxypropyltrimethoxysilane was added dropwise over a time of 25-35 minutes. After the addition was complete, the temperature was raised to 80-85°C and stirring was continued for 3.5-3.7 hours. After the reaction was completed, the mixture was cooled to room temperature and filtered to collect the solid product. The solid product was washed twice with toluene and once with anhydrous ethanol. The washed solid product was placed in a vacuum drying oven and dried under vacuum at 75-80°C for 4-5 hours. After drying, the product was pulverized and passed through a 200-mesh sieve to obtain modified hydrophobic fumed silica.

[0021] In a preferred embodiment of the present invention, the hydrophobic fumed silica, toluene, and The ratio of glycidyl etheroxypropyltrimethoxysilane used is 10-12g: 80-96mL: 1.2-1.4g.

[0022] In a preferred embodiment of the present invention, the hydrophobic fumed silica is Evonik AEROSIL® R 972.

[0023] Secondly, this application provides a method for preparing a high-temperature resistant and environmentally friendly defoamer, comprising the following steps:

[0024] Step 1: Weigh out 30-40 parts of phenyl-polyether-epoxy tri-modified polysiloxane, 1.5-3.0 parts of modified hydrophobic fumed silica, 4-7 parts of composite emulsifier, 1-2 parts of glycerol, 0.1-0.4 parts of xanthan gum, and 40-60 parts of deionized water according to the following weight proportions, and set aside for later use;

[0025] Step 2: Add phenyl-polyether-epoxy tri-modified polysiloxane and modified hydrophobic fumed silica to a reaction vessel. Stir for 2-3 hours at a temperature of 120-140℃ and a stirring rate of 300-500 r / min. Cool to 60-70℃ to obtain high-temperature silicone paste. Add deionized water to another reaction vessel, and add composite emulsifier and glycerol in sequence. Heat to 55-65℃ and stir for 10-20 minutes to obtain an aqueous phase. Add the high-temperature silicone paste dropwise to the aqueous phase, controlling the dropwise addition time to 20-40 minutes. After the dropwise addition is complete, stir for 30-50 minutes at a stirring rate of 800-1200 r / min to obtain a pre-emulsion.

[0026] Step 3: Transfer the pre-emulsion to a high-shear homogenizer and homogenize for 20-40 minutes at a speed of 6000-8000 r / min, repeating 2-3 times, while controlling the average particle size of the emulsion. Then, cool the mixture to 30-40℃, add xanthan gum, stir at low speed for 30-35 minutes, filter and discharge to obtain a high-temperature resistant and environmentally friendly defoamer.

[0027] In a preferred embodiment of the present invention, the composite emulsifier is a compound of alkyl glycoside, fatty alcohol polyoxyethylene ether and Span-80 in a mass ratio of 2:2:1; the fatty alcohol polyoxyethylene ether is AEO-9.

[0028] The beneficial effects of this invention are:

[0029] This invention discloses a high-temperature resistant and environmentally friendly defoamer and its preparation method. The method involves mixing phenyl-polyether-epoxy tri-modified polysiloxane with modified hydrophobic fumed silica to prepare a high-temperature silicone paste. A composite emulsifier, glycerol, and deionized water are then formulated into an aqueous phase. The high-temperature silicone paste is dropwise added to the aqueous phase to obtain a pre-emulsion. After high-shear homogenization, xanthan gum is added for thickening and stabilization. Filtration yields the high-temperature resistant and environmentally friendly defoamer. The phenyl-polyether-epoxy tri-modified polysiloxane provides excellent high-temperature resistance, good emulsification and dispersibility, and stable interfacial bonding for the high-temperature resistant and environmentally friendly defoamer. This defoamer combines high defoaming efficiency with environmental friendliness. Modified hydrophobic fumed silica significantly improves the high-temperature stability and foam suppression durability of the defoamer, enhances compatibility with the matrix, and prevents oil drift, demulsification, and particle sedimentation. The system uses water as the dispersion medium, is solvent-free, formaldehyde-free, and heavy metal-free, and employs environmentally friendly nonionic surfactants such as alkyl glycosides and fatty alcohol polyoxyethylene ethers. It is APEO-free, readily biodegradable, and environmentally friendly. This defoamer combines the advantages of high-temperature resistance, high stability, long-lasting defoaming and foam suppression, and APEO-free environmental friendliness, making it widely applicable and less prone to demulsification and oil drift.

[0030] In the preparation of a high-temperature resistant and environmentally friendly defoamer, a phenyl-polyether-epoxy trimodified polysiloxane was first prepared. Octamethylcyclotetrasiloxane, D4H-cyclotetrasiloxane, and octaphenylcyclotetrasiloxane were used as cyclic raw materials. Cationic ring-opening copolymerization was carried out at room temperature under the catalysis of trifluoromethanesulfonic acid. 1,1,3,3-Tetramethyldisiloxane was used as a capping agent to control the polymer molecular weight and active hydrogen content, resulting in a linear polysiloxane with Si-H side chains and phenyl main chains. This provides reaction sites for subsequent grafting modification. Then, using phenyl-modified hydrogen-containing polysiloxane intermediates and ethylene glycol monoallyl ether and polyethylene glycol monoallyl ether as raw materials, a hydrosilylation reaction occurs under the action of a Karstedt catalyst. The C=C in the allyl polyether adds to the Si-H bond of the polysiloxane side chain, grafting the polyether long chain onto the siloxane backbone to obtain phenyl-polyether dual-modified polysiloxane. Subsequently, the hydroxyl groups in the phenyl-polyether dual-modified polysiloxane react with the epoxy... Chloropropane undergoes an etherification ring-opening reaction under the phase transfer catalysis of tetrabutylammonium bromide, followed by a ring-closure reaction with the addition of sodium hydroxide, converting the end of the side chain into epoxy groups. Through ternary synergistic modification of polysiloxane with phenyl, polyether, and epoxy groups, the phenyl group, with its high rigidity and cohesive energy, can significantly improve the thermal stability of polysiloxane, ensuring that the defoamer does not demulsify or float oil under high temperature conditions, thus meeting the defoaming requirements of high-temperature systems. The polyether segment provides hydrophilicity, making the product easy to emulsify and with uniform emulsion particle size. At the same time, it works synergistically with the organosilicon backbone to achieve the dual effects of rapid defoaming and long-term foam suppression. The epoxy group can form chemical bonds or strong hydrogen bonds with the hydroxyl or siloxane groups on the surface of modified hydrophobic fumed silica, effectively enhancing the binding force between the two. This makes the silica more stable in dispersion in silicone oil, less prone to sedimentation, and does not agglomerate at high temperatures. Ultimately, the prepared defoamer has outstanding advantages such as excellent high-temperature stability, long-lasting foam suppression, strong versatility, and wide applicability.

[0031] In the process of preparing a high-temperature resistant and environmentally friendly defoamer, a modified hydrophobic fumed silica was prepared. Using the hydrophobic fumed silica as a substrate, after ultrasonic dispersion and nitrogen purification, it was combined with... Glycidyl etheroxypropyltrimethoxysilane undergoes a silanization grafting reaction to introduce epoxy groups onto the surface of silica, followed by post-treatment to obtain modified hydrophobic fumed silica. The hydrophobic fumed silica itself possesses good hydrophobicity and dispersibility. After modification with glycidyl etheroxypropyltrimethoxysilane, not only are the original hydrophobic properties retained, but epoxy groups are also introduced. These epoxy groups can form chemical bonds or strong hydrogen bonds with the epoxy groups and hydroxyl groups in the phenyl-polyether-epoxy trimethoxysilane, significantly enhancing the interfacial bonding force between silica and polysiloxane, effectively preventing silica from agglomerating and settling in the system. At the same time, the modified silica has better dispersion stability and can work synergistically with other components of the defoamer to further improve the high-temperature stability and foam suppression persistence of the defoamer, preventing demulsification and oil drift under high-temperature conditions. Its hydrophobic properties can also enhance the defoaming and foam suppression effects, meeting the overall performance requirements of high-temperature environmentally friendly defoamers. In addition, the stepwise washing and vacuum drying process can ensure product purity and avoid impurities affecting the use effect and stability of the defoamer. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1:

[0034] This embodiment describes a method for preparing a high-temperature resistant and environmentally friendly defoamer, comprising the following steps:

[0035] Step s1: 25g of octamethylcyclotetrasiloxane, 15g of D4Hcyclotetrasiloxane, 1.4g of 1,1,3,3-tetramethyldisiloxane, 1.95g of octaphenylcyclotetrasiloxane, and 0.08g of trifluoromethanesulfonic acid were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at 25℃ and a stirring rate of 300r / min for 24h. After the reaction was completed, 2.2g of anhydrous sodium bicarbonate was added and stirred for 60min. The mixture was then filtered, and the filtrate was evaporated by rotary evaporation. The filtrate was then placed in a vacuum drying oven and dried at 80℃ for 6h to obtain a phenyl-modified hydrogen-containing polysiloxane intermediate.

[0036] Step s2: Add 22g of ethylene glycol monoallyl ether, 27g of polyethylene glycol monoallyl ether (model APEG-1000), Karstedt catalyst (9ppm of total system mass), and 14.4mL of toluene to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen and stir for 15min at 80℃ and 300r / min. Add 14.4mL of phenyl-modified hydrogen-containing polysiloxane intermediate-methyl... Benzene solution (a solution of phenyl-modified hydrogen-containing polysiloxane intermediate and toluene mixed in a ratio of 13g:14.4mL) was added dropwise to a three-necked flask using a constant pressure dropping funnel, with the addition completed within 90 minutes. The mixture was then heated to 100℃ and reacted for 5 hours. After the reaction was completed, the mixture was cooled to room temperature and then subjected to rotary evaporation. The mixture was then extracted three times with n-hexane, and the organic phase was rotary evaporated again. The mixture was then placed in a vacuum drying oven and dried at 80℃ for 4 hours to obtain phenyl-polyether dual-modified polysiloxane.

[0037] Step s3: 21g of phenyl-polyether-modified polysiloxane, 26g of epichlorohydrin and 2.9g of tetrabutylammonium bromide were added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and constant pressure dropping funnel. Nitrogen gas was introduced for protection and the mixture was stirred for 6h at 80℃ and 300r / min. After cooling to room temperature, 5mL of sodium hydroxide solution (40% by mass) was added dropwise. The mixture was stirred for 4h at 50℃. After the reaction was completed, dichloromethane was added for extraction and the organic phase was washed three times with deionized water. After drying with anhydrous magnesium sulfate, the mixture was filtered. The filtrate was concentrated by rotary evaporation and then placed in a vacuum drying oven and dried for 6h at 80℃ to obtain phenyl-polyether-epoxy trimodified polysiloxane.

[0038] Step s4: Add 10g of hydrophobic fumed silica (Evonik AEROSIL® R 972) to 80mL of toluene, place it in an ultrasonic disperser, and ultrasonically disperse for 30min at 200W and 500r / min with stirring assistance. Then, purge with nitrogen gas at a rate of 50mL / min for 20min. Afterward, transfer the mixture to a three-necked flask and add it dropwise through a constant pressure dropping funnel at 75℃ and a stirring rate of 700r / min. Glycidyl etheroxypropyltrimethoxysilane was added over a controlled dropwise time of 25 min. After the addition was complete, the temperature was raised to 80 °C and the mixture was stirred for 3.5 h. After the reaction was completed, the mixture was cooled to room temperature and filtered to collect the solid product. The solid product was washed twice with toluene and once with anhydrous ethanol. The washed solid product was placed in a vacuum drying oven and dried under vacuum at 75 °C for 4 h. After that, it was pulverized and passed through a 200-mesh sieve to obtain modified hydrophobic fumed silica.

[0039] Step s5: Weigh out 30 parts by weight of phenyl-polyether-epoxy tri-modified polysiloxane, 1.5 parts by weight of modified hydrophobic fumed silica, 4 parts by weight of composite emulsifier, 1 part by weight of glycerol, 0.1 parts by weight of xanthan gum and 40 parts by weight of deionized water, and set aside.

[0040] Step s6: Add phenyl-polyether-epoxy tri-modified polysiloxane and modified hydrophobic fumed silica to a reactor and stir for 2 hours at 120°C and 300 r / min. Cool to 60°C to obtain high-temperature silicone paste. Add deionized water to another reactor and add a composite emulsifier (the composite emulsifier is a mixture of alkyl glycoside, fatty alcohol polyoxyethylene ether, and Span-80 in a mass ratio of 2:2:1, with the fatty alcohol polyoxyethylene ether being AEO-9) and glycerol in sequence. Heat to 55°C and stir for 10 minutes to obtain an aqueous phase. Add the high-temperature silicone paste dropwise to the aqueous phase, controlling the dropwise addition time to 20 minutes. After the dropwise addition is complete, stir for 30 minutes at a stirring rate of 800 r / min to obtain a pre-emulsion.

[0041] Step s7: Transfer the pre-emulsion to a high-shear homogenizer and homogenize for 20 minutes at a speed of 6000 r / min, twice, controlling the average particle size of the emulsion. Then, the temperature was lowered to 30°C, xanthan gum was added, and the mixture was stirred at low speed for 30 minutes. The mixture was then filtered to obtain a high-temperature resistant and environmentally friendly defoamer.

[0042] Example 2:

[0043] This embodiment describes a method for preparing a high-temperature resistant and environmentally friendly defoamer, comprising the following steps:

[0044] Step s1: 28g of octamethylcyclotetrasiloxane, 16.9g of D4Hcyclotetrasiloxane, 1.6g of 1,1,3,3-tetramethyldisiloxane, 2.22g of octaphenylcyclotetrasiloxane, and 0.09g of trifluoromethanesulfonic acid were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at 27℃ and a stirring rate of 350r / min for 25h. After the reaction was completed, 2.5g of anhydrous sodium bicarbonate was added and stirred for 63min. The mixture was then filtered, and the filtrate was rotary evaporated. The filtrate was then placed in a vacuum drying oven and dried at 83℃ for 6.5h to obtain a phenyl-modified hydrogen-containing polysiloxane intermediate.

[0045] Step s2: Add 23g of ethylene glycol monoallyl ether, 28g of polyethylene glycol monoallyl ether (model APEG-1000), Karstedt catalyst (Karstedt catalyst dosage is 10ppm of the total system mass), and 15.5mL of toluene to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen and stir for 17min at 83℃ and a stirring rate of 350r / min. Add 15.5mL of phenyl-modified hydrogen-containing polysiloxane intermediate-methyl... Benzene solution (a solution of phenyl-modified hydrogen-containing polysiloxane intermediate and toluene mixed at a ratio of 13g:14.4mL) was added dropwise to a three-necked flask using a constant pressure dropping funnel, with the addition completed within 95 minutes. The mixture was then heated to 100℃ and reacted for 6 hours. After the reaction was completed, the mixture was cooled to room temperature and then subjected to rotary evaporation. The mixture was then extracted three times with n-hexane, and the organic phase was rotary evaporated again. The mixture was then placed in a vacuum drying oven and dried at 83℃ for 4.5 hours to obtain phenyl-polyether dual-modified polysiloxane.

[0046] Step s3: 22g of phenyl-polyether-modified polysiloxane, 27.5g of epichlorohydrin and 3.05g of tetrabutylammonium bromide were added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and constant pressure dropping funnel. Nitrogen gas was introduced for protection, and the mixture was stirred at 83℃ and 350r / min for 6.5h. After cooling to room temperature, 5.5mL of sodium hydroxide solution (40% by mass) was added dropwise, and the mixture was stirred at 53℃ for another 4.5h. After the reaction was completed, dichloromethane was added for extraction, and the organic phase was washed three times with deionized water. After drying with anhydrous magnesium sulfate, the mixture was filtered, and the filtrate was concentrated by rotary evaporation. Then it was placed in a vacuum drying oven and dried at 83℃ for 6.5h to obtain phenyl-polyether-epoxy trimodified polysiloxane.

[0047] Step s4: Add 11g of hydrophobic fumed silica (Evonik AEROSIL® R 972) to 88mL of toluene, place it in an ultrasonic disperser, and ultrasonically disperse for 31min at 250W and 650r / min with stirring assistance. Then, purge with nitrogen gas at a rate of 65mL / min for 21min. Afterward, transfer the mixture to a three-necked flask and add it dropwise through a constant pressure dropping funnel at 78℃ and a stirring rate of 750r / min. Glycidyl etheroxypropyltrimethoxysilane was added over a controlled dropwise time of 30 min. After the addition was complete, the temperature was raised to 83 °C and the mixture was stirred for 3.6 h. After the reaction was completed, the mixture was cooled to room temperature and filtered to collect the solid product. The solid product was washed twice with toluene and once with anhydrous ethanol. The washed solid product was placed in a vacuum drying oven and dried under vacuum at 77 °C for 4.5 h. After that, it was pulverized and passed through a 200-mesh sieve to obtain modified hydrophobic fumed silica.

[0048] Step s5: Weigh out 35 parts of phenyl-polyether-epoxy tri-modified polysiloxane, 1.8 parts of modified hydrophobic fumed silica, 5.5 parts of composite emulsifier, 1.5 parts of glycerol, 0.25 parts of xanthan gum, and 50 parts of deionized water according to the following weight proportions, and set aside for later use;

[0049] Step s6: Add phenyl-polyether-epoxy tri-modified polysiloxane and modified hydrophobic fumed silica to a reactor and stir for 2.5 h at 130℃ and 400 r / min. Cool to 65℃ to obtain high-temperature silicone paste. Add deionized water to another reactor and add a composite emulsifier (the composite emulsifier is a mixture of alkyl glycoside, fatty alcohol polyoxyethylene ether, and Span-80 in a mass ratio of 2:2:1, with fatty alcohol polyoxyethylene ether being AEO-9) and glycerol in sequence. Heat to 60℃ and stir for 15 min to obtain an aqueous phase. Add the high-temperature silicone paste dropwise to the aqueous phase, controlling the dropwise addition time to 30 min. After the dropwise addition is complete, stir for 40 min at a stirring rate of 1000 r / min to obtain a pre-emulsion.

[0050] Step s7: Transfer the pre-emulsion to a high-shear homogenizer and homogenize for 30 minutes at a speed of 7000 r / min, twice, controlling the average particle size of the emulsion. Then, the temperature was lowered to 35°C, xanthan gum was added, and the mixture was stirred at low speed for 33 minutes. The mixture was then filtered to obtain a high-temperature resistant and environmentally friendly defoamer.

[0051] Example 3:

[0052] This embodiment describes a method for preparing a high-temperature resistant and environmentally friendly defoamer, comprising the following steps:

[0053] Step s1: 31g of octamethylcyclotetrasiloxane, 18.8g of D4Hcyclotetrasiloxane, 1.8g of 1,1,3,3-tetramethyldisiloxane, 2.43g of octaphenylcyclotetrasiloxane, and 0.10g of trifluoromethanesulfonic acid were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at 30℃ and a stirring rate of 400r / min for 26h. After the reaction was completed, 2.8g of anhydrous sodium bicarbonate was added and stirred for 65min. The mixture was then filtered, and the filtrate was evaporated by rotary evaporation. The filtrate was then placed in a vacuum drying oven and dried at 85℃ for 7h to obtain a phenyl-modified hydrogen-containing polysiloxane intermediate.

[0054] Step s2: Add 24g of ethylene glycol monoallyl ether, 29g of polyethylene glycol monoallyl ether (model APEG-1000), Karstedt catalyst (11ppm of total system mass), and 15.7mL of toluene to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen and stir for 20min at 85℃ and 400r / min. Add 15.7mL of phenyl-modified hydrogen-containing polysiloxane intermediate-methyl... Benzene solution (a solution of phenyl-modified hydrogen-containing polysiloxane intermediate and toluene mixed in a ratio of 13g:14.4mL) was added dropwise to a three-necked flask using a constant pressure dropping funnel, with the addition completed within 100 minutes. The mixture was then heated to 100℃ and reacted for 7 hours. After the reaction was completed, the mixture was cooled to room temperature and then subjected to rotary evaporation. The mixture was then extracted four times with n-hexane, and the organic phase was rotary evaporated again. The mixture was then placed in a vacuum drying oven and dried at 85℃ for 5 hours to obtain phenyl-polyether dual-modified polysiloxane.

[0055] Step s3: 23g of phenyl-polyether-modified polysiloxane, 29g of epichlorohydrin and 3.2g of tetrabutylammonium bromide were added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and constant pressure dropping funnel. Nitrogen gas was introduced for protection and the mixture was stirred at 85℃ and 400r / min for 7h. After cooling to room temperature, 6mL of sodium hydroxide solution (40% by mass) was added dropwise. The mixture was stirred at 55℃ for 5h. After the reaction was completed, dichloromethane was added for extraction and the organic phase was washed four times with deionized water. After drying with anhydrous magnesium sulfate, the mixture was filtered. The filtrate was concentrated by rotary evaporation and then placed in a vacuum drying oven and dried at 85℃ for 7h to obtain phenyl-polyether-epoxy trimodified polysiloxane.

[0056] Step s4: Add 12g of hydrophobic fumed silica (Evonik AEROSIL® R 972) to 96mL of toluene, place it in an ultrasonic disperser, and ultrasonically disperse for 32min at 300W and 800r / min with stirring assistance. Then, purge with nitrogen gas at 80mL / min for 22min. Afterward, transfer to a three-necked flask and add the silica dropwise through a constant pressure dropping funnel at 80℃ and 800r / min. Glycidyl etheroxypropyltrimethoxysilane was added over a controlled dropwise time of 35 min. After the addition was complete, the temperature was raised to 85 °C and the mixture was stirred for 3.7 h. After the reaction was completed, the mixture was cooled to room temperature and filtered to collect the solid product. The solid product was washed twice with toluene and once with anhydrous ethanol. The washed solid product was placed in a vacuum drying oven and dried under vacuum at 80 °C for 5 h. After that, it was pulverized and passed through a 200-mesh sieve to obtain modified hydrophobic fumed silica.

[0057] Step s5: Weigh out 40 parts of phenyl-polyether-epoxy tri-modified polysiloxane, 3.0 parts of modified hydrophobic fumed silica, 7 parts of composite emulsifier, 2 parts of glycerol, 0.4 parts of xanthan gum, and 60 parts of deionized water according to the following weight proportions, and set aside for later use;

[0058] Step s6: Add phenyl-polyether-epoxy tri-modified polysiloxane and modified hydrophobic fumed silica to a reactor and stir for 3 hours at 140°C and 500 r / min. Cool to 70°C to obtain high-temperature silicone paste. Add deionized water to another reactor and add a composite emulsifier (the composite emulsifier is a mixture of alkyl glycoside, fatty alcohol polyoxyethylene ether, and Span-80 in a mass ratio of 2:2:1, with the fatty alcohol polyoxyethylene ether being AEO-9) and glycerol in sequence. Heat to 65°C and stir for 20 minutes to obtain an aqueous phase. Add the high-temperature silicone paste dropwise to the aqueous phase, controlling the dropwise addition time to 40 minutes. After the dropwise addition is complete, stir for 50 minutes at a stirring rate of 1200 r / min to obtain a pre-emulsion.

[0059] Step s7: Transfer the pre-emulsion to a high-shear homogenizer and homogenize for 40 minutes at a homogenization speed of 8000 r / min, repeating 3 times, controlling the average particle size of the emulsion. Then, the temperature was lowered to 40°C, xanthan gum was added, and the mixture was stirred at low speed for 35 minutes. The mixture was then filtered to obtain a high-temperature resistant and environmentally friendly defoamer.

[0060] Comparative Example 1:

[0061] This comparative example illustrates a method for preparing a high-temperature resistant and environmentally friendly defoamer, comprising the following steps:

[0062] Step s1: 25g of octamethylcyclotetrasiloxane, 15g of D4Hcyclotetrasiloxane, 1.4g of 1,1,3,3-tetramethyldisiloxane, 1.95g of octaphenylcyclotetrasiloxane, and 0.08g of trifluoromethanesulfonic acid were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at 25℃ and a stirring rate of 300r / min for 24h. After the reaction was completed, 2.2g of anhydrous sodium bicarbonate was added and stirred for 60min. The mixture was then filtered, and the filtrate was evaporated by rotary evaporation. The filtrate was then placed in a vacuum drying oven and dried at 80℃ for 6h to obtain a phenyl-modified hydrogen-containing polysiloxane intermediate.

[0063] Step s2: Add 22g of ethylene glycol monoallyl ether, 27g of polyethylene glycol monoallyl ether (model APEG-1000), Karstedt catalyst (9ppm of total system mass), and 14.4mL of toluene to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen and stir for 15min at 80℃ and 300r / min. Add 14.4mL of phenyl-modified hydrogen-containing polysiloxane intermediate-methyl... Benzene solution (a solution of phenyl-modified hydrogen-containing polysiloxane intermediate and toluene mixed in a ratio of 13g:14.4mL) was added dropwise to a three-necked flask using a constant pressure dropping funnel, with the addition completed within 90 minutes. The mixture was then heated to 100℃ and reacted for 5 hours. After the reaction was completed, the mixture was cooled to room temperature and then subjected to rotary evaporation. The mixture was then extracted three times with n-hexane, and the organic phase was rotary evaporated again. The mixture was then placed in a vacuum drying oven and dried at 80℃ for 4 hours to obtain phenyl-polyether dual-modified polysiloxane.

[0064] Step s3: Add 10g of hydrophobic fumed silica (Evonik AEROSIL® R 972) to 80mL of toluene, place it in an ultrasonic disperser, and ultrasonically disperse for 30min at 200W and 500r / min with stirring assistance. Then, purge with nitrogen gas at a rate of 50mL / min for 20min. Afterward, transfer the solution to a three-necked flask and add it dropwise through a constant pressure dropping funnel at 75℃ and a stirring rate of 700r / min. Glycidyl etheroxypropyltrimethoxysilane was added over a controlled dropwise time of 25 min. After the addition was complete, the temperature was raised to 80 °C and the mixture was stirred for 3.5 h. After the reaction was completed, the mixture was cooled to room temperature and filtered to collect the solid product. The solid product was washed twice with toluene and once with anhydrous ethanol. The washed solid product was placed in a vacuum drying oven and dried under vacuum at 75 °C for 4 h. After that, it was pulverized and passed through a 200-mesh sieve to obtain modified hydrophobic fumed silica.

[0065] Step s4: Weigh out 30 parts of phenyl-polyether dual-modified polysiloxane, 1.5 parts of modified hydrophobic fumed silica, 4 parts of composite emulsifier, 1 part of glycerol, 0.1 parts of xanthan gum, and 40 parts of deionized water according to the following weight proportions, and set aside for later use;

[0066] Step s5: Add phenyl-polyether-modified polysiloxane and modified hydrophobic fumed silica to a reactor and stir for 2 hours at 120°C and 300 r / min. Cool to 60°C to obtain high-temperature silicone paste. Add deionized water to another reactor and add a composite emulsifier (the composite emulsifier is a mixture of alkyl glycoside, fatty alcohol polyoxyethylene ether, and Span-80 in a mass ratio of 2:2:1, with the fatty alcohol polyoxyethylene ether being AEO-9) and glycerol in sequence. Heat to 55°C and stir for 10 minutes to obtain an aqueous phase. Add the high-temperature silicone paste dropwise to the aqueous phase, controlling the dropwise addition time to 20 minutes. After the dropwise addition is complete, stir for 30 minutes at a stirring rate of 800 r / min to obtain a pre-emulsion.

[0067] Step s6: Transfer the pre-emulsion to a high-shear homogenizer and homogenize for 20 minutes at a speed of 6000 r / min, twice, controlling the average particle size of the emulsion. Then, the temperature was lowered to 30°C, xanthan gum was added, and the mixture was stirred at low speed for 30 minutes. The mixture was then filtered to obtain a high-temperature resistant and environmentally friendly defoamer.

[0068] Comparative Example 2:

[0069] This comparative example illustrates a method for preparing a high-temperature resistant and environmentally friendly defoamer, comprising the following steps:

[0070] Step s1: 25g of octamethylcyclotetrasiloxane, 15g of D4Hcyclotetrasiloxane, 1.4g of 1,1,3,3-tetramethyldisiloxane, 1.95g of octaphenylcyclotetrasiloxane, and 0.08g of trifluoromethanesulfonic acid were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at 25℃ and a stirring rate of 300r / min for 24h. After the reaction was completed, 2.2g of anhydrous sodium bicarbonate was added and stirred for 60min. The mixture was then filtered, and the filtrate was evaporated by rotary evaporation. The filtrate was then placed in a vacuum drying oven and dried at 80℃ for 6h to obtain a phenyl-modified hydrogen-containing polysiloxane intermediate.

[0071] Step s2: Add 22g of ethylene glycol monoallyl ether, 27g of polyethylene glycol monoallyl ether (model APEG-1000), Karstedt catalyst (9ppm of total system mass), and 14.4mL of toluene to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen and stir for 15min at 80℃ and 300r / min. Add 14.4mL of phenyl-modified hydrogen-containing polysiloxane intermediate-methyl... Benzene solution (a solution of phenyl-modified hydrogen-containing polysiloxane intermediate and toluene mixed in a ratio of 13g:14.4mL) was added dropwise to a three-necked flask using a constant pressure dropping funnel, with the addition completed within 90 minutes. The mixture was then heated to 100℃ and reacted for 5 hours. After the reaction was completed, the mixture was cooled to room temperature and then subjected to rotary evaporation. The mixture was then extracted three times with n-hexane, and the organic phase was rotary evaporated again. The mixture was then placed in a vacuum drying oven and dried at 80℃ for 4 hours to obtain phenyl-polyether dual-modified polysiloxane.

[0072] Step s3: 21g of phenyl-polyether-modified polysiloxane, 26g of epichlorohydrin and 2.9g of tetrabutylammonium bromide were added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube and constant pressure dropping funnel. Nitrogen gas was introduced for protection and the mixture was stirred for 6h at 80℃ and 300r / min. After cooling to room temperature, 5mL of sodium hydroxide solution (40% by mass) was added dropwise. The mixture was stirred for 4h at 50℃. After the reaction was completed, dichloromethane was added for extraction and the organic phase was washed three times with deionized water. After drying with anhydrous magnesium sulfate, the mixture was filtered. The filtrate was concentrated by rotary evaporation and then placed in a vacuum drying oven and dried for 6h at 80℃ to obtain phenyl-polyether-epoxy trimodified polysiloxane.

[0073] Step s4: Weigh out 30 parts by weight of phenyl-polyether-epoxy tri-modified polysiloxane, 1.5 parts by weight of hydrophobic fumed silica, 4 parts by weight of composite emulsifier, 1 part by weight of glycerol, 0.1 parts by weight of xanthan gum and 40 parts by weight of deionized water, and set aside.

[0074] Step s5: Add phenyl-polyether-epoxy tri-modified polysiloxane and hydrophobic fumed silica (hydrophobic fumed silica model is Evonik AEROSIL® R 972) to a reactor and stir for 2 hours at 120℃ and 300 r / min. Cool to 60℃ to obtain high-temperature silicone paste. Add deionized water to another reactor and add a composite emulsifier (the composite emulsifier is a mixture of alkyl glycoside, fatty alcohol polyoxyethylene ether, and Span-80 in a mass ratio of 2:2:1, the fatty alcohol polyoxyethylene ether model is AEO-9) and glycerol in sequence. Heat to 55℃ and stir for 10 min to obtain an aqueous phase. Add the high-temperature silicone paste dropwise to the aqueous phase, controlling the dropwise addition time to 20 min. After the dropwise addition is complete, stir for 30 min at a stirring rate of 800 r / min to obtain a pre-emulsion.

[0075] Step s6: Transfer the pre-emulsion to a high-shear homogenizer and homogenize for 20 minutes at a speed of 6000 r / min, twice, controlling the average particle size of the emulsion. Then, the temperature was lowered to 30°C, xanthan gum was added, and the mixture was stirred at low speed for 30 minutes. The mixture was then filtered to obtain a high-temperature resistant and environmentally friendly defoamer.

[0076] Comparative Example 3:

[0077] This comparative example illustrates a method for preparing a high-temperature resistant and environmentally friendly defoamer, comprising the following steps:

[0078] Step s1: 25g of octamethylcyclotetrasiloxane, 15g of D4Hcyclotetrasiloxane, 1.4g of 1,1,3,3-tetramethyldisiloxane, 1.95g of octaphenylcyclotetrasiloxane, and 0.08g of trifluoromethanesulfonic acid were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred and reacted at 25℃ and a stirring rate of 300r / min for 24h. After the reaction was completed, 2.2g of anhydrous sodium bicarbonate was added and stirred for 60min. The mixture was then filtered, and the filtrate was evaporated by rotary evaporation. The filtrate was then placed in a vacuum drying oven and dried at 80℃ for 6h to obtain a phenyl-modified hydrogen-containing polysiloxane intermediate.

[0079] Step s2: Add 22g of ethylene glycol monoallyl ether, 27g of polyethylene glycol monoallyl ether (model APEG-1000), Karstedt catalyst (9ppm of total system mass), and 14.4mL of toluene to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen and stir for 15min at 80℃ and 300r / min. Add 14.4mL of phenyl-modified hydrogen-containing polysiloxane intermediate-methyl... Benzene solution (a solution of phenyl-modified hydrogen-containing polysiloxane intermediate and toluene mixed in a ratio of 13g:14.4mL) was added dropwise to a three-necked flask using a constant pressure dropping funnel, with the addition completed within 90 minutes. The mixture was then heated to 100℃ and reacted for 5 hours. After the reaction was completed, the mixture was cooled to room temperature and then subjected to rotary evaporation. The mixture was then extracted three times with n-hexane, and the organic phase was rotary evaporated again. The mixture was then placed in a vacuum drying oven and dried at 80℃ for 4 hours to obtain phenyl-polyether dual-modified polysiloxane.

[0080] Step s3: Weigh out 30 parts of phenyl-polyether dual-modified polysiloxane, 1.5 parts of hydrophobic fumed silica, 4 parts of composite emulsifier, 1 part of glycerol, 0.1 parts of xanthan gum, and 40 parts of deionized water according to the following weight proportions, and set aside for later use;

[0081] Step s4: Add phenyl-polyether-modified polysiloxane and hydrophobic fumed silica (hydrophobic fumed silica model is Evonik AEROSIL® R 972) to a reactor and stir for 2 hours at 120°C and 300 r / min. Cool to 60°C to obtain high-temperature silicone paste. Add deionized water to another reactor and add a composite emulsifier (the composite emulsifier is a mixture of alkyl glycoside, fatty alcohol polyoxyethylene ether, and Span-80 in a mass ratio of 2:2:1, the fatty alcohol polyoxyethylene ether model is AEO-9) and glycerol in sequence. Heat to 55°C and stir for 10 min to obtain an aqueous phase. Add the high-temperature silicone paste dropwise to the aqueous phase, controlling the dropwise addition time to 20 min. After the dropwise addition is complete, stir for 30 min at a stirring rate of 800 r / min to obtain a pre-emulsion.

[0082] Step s5: Transfer the pre-emulsion to a high-shear homogenizer and homogenize for 20 minutes at a speed of 6000 r / min, twice, controlling the average particle size of the emulsion. Then, the temperature was lowered to 30°C, xanthan gum was added, and the mixture was stirred at low speed for 30 minutes. The mixture was then filtered to obtain a high-temperature resistant and environmentally friendly defoamer.

[0083] Performance testing:

[0084] The high-temperature resistant and environmentally friendly defoamers of Examples 1-3 and Comparative Examples 1-3 were tested for performance according to the following methods;

[0085] Defoaming speed test: Prepare a 0.1% defoamer aqueous solution, take 100mL and place it in a stoppered graduated cylinder, shake vigorously for 30s, and record the time required for the foam to completely disappear. The shorter the time, the faster the defoaming speed.

[0086] Defoaming time test: Prepare a 0.1% defoamer aqueous solution, take 100mL and place it in a stoppered graduated cylinder, shake vigorously for 30s, and record the time required from the appearance of foam until the foam height returns to the initial liquid level. The longer the time, the better the defoaming performance.

[0087] High-temperature stability test: Place the defoamer in a 150℃ constant temperature oven and keep it at the constant temperature for 24 hours. Take it out and cool it to room temperature. Observe the appearance of the defoamer (whether it separates, changes color, or clumps). Retest its defoaming speed and calculate the defoaming speed change rate [change rate = (defoaming speed after treatment - defoaming speed before treatment) / defoaming speed before treatment × 100%]. The smaller the absolute value of the change rate, the better the high-temperature stability.

[0088] Emulsion stability test: Place the defoamer in a centrifuge tube and centrifuge at 3000 r / min for 30 min. Observe whether the emulsion separates into layers. If there is no separation, it is qualified. At the same time, test the average particle size of the emulsion. The smaller the particle size and the more uniform the distribution, the better the emulsion stability.

[0089] The test results are shown in Table 1:

[0090] Table 1: Test Results Summary Table

[0091]

[0092] Referring to Table 1, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the synergistic effect of phenyl-polyether-epoxy trimodified polysiloxane and modified hydrophobic fumed silica can significantly improve defoaming and foam suppression performance. The introduction of epoxy groups can enhance the compatibility of the defoamer with the system and further optimize the defoaming effect. This high-temperature resistant and environmentally friendly defoamer has fast defoaming speed, long foam suppression time, excellent high-temperature stability, uniform emulsion dispersion and good stability, and also has environmental protection characteristics, and can continuously exert efficient defoaming and foam suppression effects in high-temperature environments.

[0093] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0094] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A high-temperature-resistant, environmentally friendly defoamer, characterized in that, Includes the following components by weight: 30-40 parts of phenyl-polyether-epoxy tri-modified polysiloxane, 1.5-3.0 parts of modified hydrophobic fumed silica, 4-7 parts of composite emulsifier, 1-2 parts of glycerol, 0.1-0.4 parts of xanthan gum, and 40-60 parts of deionized water; The phenyl-polyether-epoxy tri-modified polysiloxane is prepared by the following steps: Step a1: Octamethylcyclotetrasiloxane, D4Hcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, octaphenylcyclotetrasiloxane and trifluoromethanesulfonic acid were added to a three-necked flask and stirred to react. Then anhydrous sodium bicarbonate was added and stirred. The mixture was filtered and rotary evaporated, and dried to obtain phenyl-modified hydrogen-containing polysiloxane intermediate. Step a2: Ethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, Karstedt catalyst and toluene were added to a three-necked flask and stirred. A phenyl-modified hydrogen-containing polysiloxane intermediate-toluene solution was added dropwise. The reaction was then heated and continued. After cooling, the mixture was rotary evaporated and extracted with n-hexane. The organic phase was rotary evaporated again and then dried to obtain phenyl-polyether bis-modified polysiloxane. Step a3: Add phenyl-polyether bis-modified polysiloxane, epichlorohydrin and tetrabutylammonium bromide to a three-necked flask and stir. Then cool, add sodium hydroxide solution dropwise, continue stirring, add dichloromethane for extraction, wash, dry, concentrate by rotary evaporation, and then dry to obtain phenyl-polyether-epoxy tri-modified polysiloxane. The modified hydrophobic fumed silica is prepared by the following steps: Hydrophobic fumed silica was added to toluene and ultrasonically dispersed. The mixture was then transferred to a three-necked flask, and γ-glycidoxypropyltrimethoxysilane was added dropwise. The mixture was heated and stirred continuously, then cooled, filtered, washed, and vacuum dried. Finally, it was pulverized and sieved to obtain modified hydrophobic fumed silica.

2. The high-temperature-resistant environmentally friendly defoamer according to claim 1, characterized in that, The ratio of octamethylcyclotetrasiloxane, D4H-cyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, octaphenylcyclotetrasiloxane, trifluoromethanesulfonic acid, and anhydrous sodium bicarbonate in step a1 is 25-31g: 15.0-18.8g: 1.4-1.8g: 1.95-2.43g: 0.08-0.10g: 2.2-2.8g; the ratio of ethylene glycol monoallyl ether and polyethylene glycol monoallyl ether in step a2 is 25-31g: 15.0-18.8g: 1.4-1.8g: 1.95-2.43g: 0.08-0.10g: 2.2-2.8g. The ratio of the amount of glycol monoallyl ether, toluene, and phenyl-modified hydrogen-containing polysiloxane intermediate-toluene solution is 22-24g:27-29g:14.4-15.7mL:14.4-15.7mL; the ratio of the amount of phenyl-polyether bis-modified polysiloxane, epichlorohydrin, tetrabutylammonium bromide, and sodium hydroxide solution in step a3 is 21-23g:26-29g:2.9-3.2g:5-6mL.

3. The high-temperature resistant and environmentally friendly defoamer according to claim 1, characterized in that, The amount of Karstedt catalyst used in step a2 is 9-11 ppm of the total system mass.

4. The high-temperature resistant and environmentally friendly defoamer according to claim 1, characterized in that, The phenyl-modified hydrogen-containing polysiloxane intermediate-toluene solution in step a2 is a solution prepared by mixing phenyl-modified hydrogen-containing polysiloxane intermediate and toluene in a ratio of 13g:14.4mL.

5. The high-temperature resistant and environmentally friendly defoamer according to claim 1, characterized in that, The sodium hydroxide solution in step a3 has a mass fraction of 40%.

6. The high-temperature resistant and environmentally friendly defoamer according to claim 1, characterized in that, The ratio of hydrophobic fumed silica, toluene, and γ-glycidoxypropyltrimethoxysilane used in the process is 10-12g: 80-96mL: 1.2-1.4g.

7. A method for preparing a high-temperature resistant and environmentally friendly defoamer, characterized in that, The preparation of the high-temperature resistant and environmentally friendly defoamer as described in any one of claims 1-6 includes the following steps: Step 1: Weigh out 30-40 parts of phenyl-polyether-epoxy tri-modified polysiloxane, 1.5-3.0 parts of modified hydrophobic fumed silica, 4-7 parts of composite emulsifier, 1-2 parts of glycerol, 0.1-0.4 parts of xanthan gum, and 40-60 parts of deionized water according to the following weight proportions, and set aside for later use; Step 2: Add phenyl-polyether-epoxy tri-modified polysiloxane and modified hydrophobic fumed silica to a reaction vessel and stir. Cool to obtain high-temperature silicone paste. Add deionized water to another reaction vessel, and add composite emulsifier and glycerol in sequence. Heat and stir to obtain an aqueous phase. Add the high-temperature silicone paste dropwise to the aqueous phase. Stir after the dropwise addition is complete to obtain a pre-emulsion. Step 3: Transfer the pre-emulsion to a high-shear homogenizer for homogenization, control the average particle size of the emulsion to ≤2μm, then cool it down, add xanthan gum, stir at low speed, filter and discharge to obtain a high-temperature resistant and environmentally friendly defoamer.

8. The preparation method of a high-temperature resistant and environmentally friendly defoamer according to claim 7, characterized in that, The composite emulsifier is a mixture of alkyl glycoside, fatty alcohol polyoxyethylene ether, and Span-80 in a mass ratio of 2:2:1.

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