A high temperature resistant organosilicon defoamer and preparation method thereof

Abstract

The present invention relates to the technical field of defoamers for sewage treatment, and specifically to a high temperature resistant organosilicon defoamer and a preparation method thereof. The high temperature resistant organosilicon defoamer comprises the following raw materials in parts by weight: 20-50 parts of modified polysiloxane, 1-10 parts of emulsifier, 0.1-2 parts of surface tension regulator, 0.2-8 parts of other auxiliary agents and 40-60 parts of solvent. The high temperature resistant organosilicon defoamer has excellent high temperature resistance, weather resistance and chemical stability, can maintain stability under high temperature environment, effectively destroy the stability of foam, and enable gas and liquid to fully contact, thereby achieving the effect of defoaming, and the high temperature resistant organosilicon defoamer can spread on the surface of sewage to form a very thin and uniform molecular film, which not only has the effect of reducing surface tension, but also can prevent bubble formation, improve the efficiency of the entire treatment process, and is particularly suitable for the defoaming and anti-foaming requirements of sewage high temperature treatment process.

Description

Technical Field

[0001] The invention relates to the technical field of defoamers for sewage treatment, and in particular to a high temperature resistant organosilicon defoamer and a preparation method thereof. Background Art

[0002] With the growth of population, industrialization and urbanization, the demand for water resources is increasing, but the available freshwater resources are relatively limited. This unbalanced distribution and over-exploitation have led to water shortages in many regions. At the same time, industrial wastewater, agricultural non-point source pollution and urban domestic sewage have caused serious pollution to the water environment. Pollutants such as organic matter, inorganic matter, heavy metals and microorganisms in water bodies pose a serious threat to aquatic ecosystems and human health.

[0003] In the sewage treatment process, since the sewage contains a large amount of suspended matter, organic matter and gas, these substances are prone to form foam under certain conditions. The presence of foam will not only affect the normal operation of sewage treatment equipment and reduce treatment efficiency, but may also have an adverse effect on the effluent quality. Specifically, the foam will occupy the effective volume of the reactor or sedimentation tank, resulting in a reduction in the amount of treated water; at the same time, harmful substances in the foam may overflow with the foam and pollute the surrounding environment.

[0004] In order to effectively remove the foam in sewage and improve the sewage treatment efficiency and water quality, it is necessary to take corresponding defoaming measures. Defoaming agent, as a chemical agent, destroys the stable structure of foam and makes the foam dissipate quickly, thus achieving the purpose of defoaming. In the sewage treatment process, choosing the right defoaming agent is crucial to ensure the treatment effect.

[0005] In processes that require high-temperature sewage treatment, such as negative pressure high-temperature MVR evaporator wastewater distillation, conventional defoamers are prone to demulsification and oil floating at high temperatures, losing their defoaming effect and may even cause further pollution. Summary of the invention

[0006] In order to overcome the shortcomings and deficiencies in the prior art, one of the objects of the present invention is to provide a high-temperature resistant organosilicon defoamer, which has excellent high-temperature resistance, weather resistance and chemical stability, can maintain stability in a high-temperature environment, effectively destroy the stability of the foam, and enable the gas and liquid to fully contact, thereby achieving the defoaming effect. The high-temperature resistant organosilicon defoamer can spread on the surface of sewage to form a very thin and uniform molecular film, which not only has the effect of reducing surface tension, but also can prevent bubble formation, thereby improving the efficiency of the entire treatment process. It is particularly suitable for the defoaming and anti-foaming needs of high-temperature sewage treatment processes.

[0007] The second object of the present invention is to provide a method for preparing a high temperature resistant organosilicon defoamer, which has simple operation, convenient control, high production efficiency, low production cost, and can be used for large-scale production.

[0008] One of the purposes of the present invention is achieved by the following technical solution: A high temperature resistant silicone defoamer comprises the following raw materials in parts by weight:

[0009]

[0010] The high temperature resistant silicone defoamer has excellent high temperature resistance, weather resistance and chemical stability. It can maintain the stability of the defoamer in a high temperature environment, effectively destroy the stability of the foam, and allow the gas and liquid to fully contact, thereby achieving the defoaming effect. The high temperature resistant silicone defoamer can spread on the surface of sewage to form a very thin and uniform molecular film, which not only has the effect of reducing surface tension, but also can prevent the formation of bubbles, improve the efficiency of the entire treatment process, and is particularly suitable for the defoaming and anti-foaming needs of the high temperature treatment process of sewage. Among them, the modified polysiloxane used shows higher heat resistance, weather resistance and chemical stability after special modification, can maintain its stable performance under high temperature and harsh environment, can effectively destroy the stability of the foam, thereby achieving the defoaming effect, can quickly spread on the foam surface, reduce the surface tension of the foam, and prevent the formation of bubbles. Compared with ordinary defoamers, the high temperature resistant defoamer not only has a fast defoaming speed, but also has a longer anti-foaming time, and can maintain the stability of water quality for a long time. The added emulsifier has excellent emulsifying, wetting, dispersing and thickening properties, which promotes the uniform dispersion of modified polysiloxane in the water phase to form a stable emulsion, so as to better exert the defoaming effect of modified polysiloxane. The added surface tension regulator is conducive to adjusting the surface tension of the defoamer, making it easier to spread on the foam surface and destroy the foam. The added other additives are conducive to further enhancing its heat resistance, chemical resistance, stability and improving fluidity, thereby optimizing its performance and improving defoaming efficiency.

[0011] Preferably, the preparation method of each modified polysiloxane comprises the following steps:

[0012] (R1), take 100 parts of dimethyldimethoxysilane, 20-30 parts of methylphenylsiloxane, 8-12 parts of cyclic siloxane monomer, 1-2 parts of hydrolysis catalyst, 5-8 parts of modifier, 100 parts of extractant and 50-80 parts of water by weight, and set aside;

[0013] (R2), adding dimethyldimethoxysilane and a hydrolysis catalyst to water, mixing evenly, heating to 80-95°C for reaction for 2-4h, removing impurities by reduced pressure distillation, and then reacting at 75-85°C for 1-2h to obtain oligosiloxane;

[0014] (R3), adding methylphenylsiloxane, cyclic siloxane monomer and modifier to the oligosiloxane, mixing evenly, reacting at 75-85° C. for 4-6 hours, cooling, and obtaining a mixed product;

[0015] (R4), adding an extractant to the mixed product, mixing and letting stand, taking the organic phase, and removing the extractant by vacuum distillation to obtain a modified polysiloxane.

[0016] By adopting the above technical scheme, dimethyldimethoxysilane is alcoholyzed and pre-condensed under a hydrolysis catalyst, a specific temperature and an impurity removal effect to obtain an oligosiloxane, and then methylphenylsiloxane, a cyclic siloxane monomer and a modifier are added for co-condensation to introduce phenyl, alkoxy and titanium hydroxy compounds. The modifier also promotes the cross-linking of the system to form a cross-linked network structure, which is more conducive to improving the chemical stability and heat resistance of the modified polysiloxane, thereby improving the overall high-temperature defoaming and anti-foaming performance of the defoamer.

[0017] Preferably, the cyclic siloxane monomer is dimethylcyclosiloxane or octamethylcyclotetrasiloxane; and the modifier is prepared by mixing aluminum isopropoxide and n-butyl titanate in a molar ratio of 1:1-3.

[0018] By adopting the above technical scheme, the modifier is mixed with aluminum isopropoxide and n-butyl titanate in a molar ratio of 1:1-3. The introduced aluminum isopropoxide and titanium element can form a stable chemical bond, which significantly improves the heat resistance and chemical stability of the modified polysiloxane, so as to promote the high-temperature defoaming and anti-foaming performance of the defoaming agent.

[0019] Preferably, the hydrolysis catalyst is glacial acetic acid, and the extractant is xylene or acetylacetone.

[0020] Preferably, the emulsifier is at least one of polyoxyethylene sorbitan monostearate, sorbitan monooleate polyoxyethylene ether and sodium dodecylbenzene sulfonate.

[0021] Preferably, the surface tension regulator is a mixture of fatty amine polyoxyethylene ether and carboxylate anionic fluorocarbon surfactant in a weight ratio of 3:0.001-0.003.

[0022] By adopting the above technical scheme, the fatty amine polyoxyethylene ether and the carboxylate anionic fluorocarbon surfactant work synergistically to improve the dispersibility, spreadability and stability of the defoamer, and jointly enhance the defoaming and anti-foaming ability of the defoamer; and the carboxylate anionic fluorocarbon surfactant has high thermal stability, and the non-polar group of the fluorocarbon chain can enhance the adsorption capacity of the defoamer on the foam surface, thereby further improving the defoaming effect. More preferably, the carboxylate anionic fluorocarbon surfactant is selected from FSA is a water-soluble carboxylate anionic fluorocarbon surfactant.

[0023] Preferably, each part of the other auxiliary agents includes 0.1-5 parts of stabilizer and 0.1-3 parts of thickener.

[0024] Preferably, the stabilizer is polyvinyl alcohol and / or sodium polyacrylate; the thickener is carboxymethyl cellulose and / or hydroxypropyl methyl cellulose.

[0025] By adopting the above technical scheme, the above stabilizer in the high temperature resistant silicone defoamer mainly plays the role of enhancing the product's heat resistance, chemical resistance and long-term storage stability; the thickener is used to adjust the viscosity of the high temperature resistant silicone defoamer to make it easier to use and control.

[0026] Preferably, the solvent is deionized water.

[0027] The second object of the present invention is achieved by the following technical solution: The preparation method of the above-mentioned high temperature resistant silicone defoamer comprises the following steps:

[0028] (S1), taking modified polysiloxane, emulsifier, surface tension regulator, other additives and solvent according to weight parts for later use;

[0029] (S2), uniformly mixing the modified polysiloxane and the emulsifier to obtain a mixture;

[0030] (S3), adding a solvent to the mixture, stirring, and obtaining an emulsion;

[0031] (S4), adding a surface tension regulator and other additives to the emulsion, and stirring to obtain a high temperature resistant organosilicon defoamer.

[0032] The beneficial effects of the present invention are as follows: the high-temperature resistant organosilicon defoamer of the present invention has excellent high-temperature resistance, weather resistance and chemical stability, can maintain the stability of the defoamer in a high-temperature environment, effectively destroy the stability of the foam, and enable the gas and liquid to fully contact, thereby achieving the defoaming effect, and the high-temperature resistant organosilicon defoamer can spread on the surface of sewage to form a very thin and uniform molecular film, which not only has the effect of reducing surface tension, but also can prevent bubble formation, thereby improving the efficiency of the entire treatment process, and is particularly suitable for the defoaming and anti-foaming needs of the high-temperature treatment process of sewage.

[0033] The preparation method of the high temperature resistant organosilicon defoamer of the present invention is simple to operate, convenient to control, high in production efficiency, low in production cost, and can be used for large-scale production. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0035] Example 1

[0036] A high temperature resistant organic silicon defoamer comprises the following raw materials in parts by weight: 35 parts of modified polysiloxane, 5 parts of emulsifier, 1 part of surface tension regulator, 4 parts of other additives and 50 parts of solvent.

[0037] The preparation method of each modified polysiloxane comprises the following steps:

[0038] (R1), take 100 parts of dimethyldimethoxysilane, 25 parts of methylphenylsiloxane, 10 parts of cyclic siloxane monomer, 1.5 parts of hydrolysis catalyst, 6 parts of modifier, 100 parts of extractant and 65 parts of water by weight, and set aside;

[0039] (R2), adding dimethyldimethoxysilane and a hydrolysis catalyst to water, mixing evenly, heating to 90°C for reaction for 3 hours, removing impurities by reduced pressure distillation, and then reacting at 80°C for 1.5 hours to obtain oligosiloxane;

[0040] (R3), adding methylphenylsiloxane, cyclic siloxane monomer and modifier to the oligosiloxane, mixing evenly, reacting at 80° C. for 5 h, cooling, and obtaining a mixed product;

[0041] (R4), adding an extractant to the mixed product, mixing and letting stand, taking the organic phase, and removing the extractant by vacuum distillation to obtain a modified polysiloxane.

[0042] The cyclic siloxane monomer is octamethylcyclotetrasiloxane; the modifier is prepared by mixing aluminum isopropoxide and n-butyl titanate in a molar ratio of 1:2.

[0043] The hydrolysis catalyst is glacial acetic acid, and the extractant is acetylacetone.

[0044] The emulsifier is polyoxyethylene sorbitan monostearate.

[0045] The surface tension regulator is a fatty amine polyoxyethylene ether and a carboxylate anionic fluorocarbon surfactant. FSA is mixed in a weight ratio of 3:0.002.

[0046] Each part of the other auxiliary agents includes 3 parts of stabilizers and 2 parts of thickeners.

[0047] The stabilizer is a mixture of polyvinyl alcohol and sodium polyacrylate in a weight ratio of 1:3; the thickener is a mixture of carboxymethyl cellulose and hydroxypropyl methyl cellulose in a weight ratio of 1:6.

[0048] The solvent is deionized water.

[0049] The preparation method of the high temperature resistant organosilicon defoamer comprises the following steps:

[0050] (S1), taking modified polysiloxane, emulsifier, surface tension regulator, other additives and solvent according to weight parts for later use;

[0051] (S2), uniformly mixing the modified polysiloxane and the emulsifier to obtain a mixture;

[0052] (S3), adding a solvent to the mixture, stirring, and obtaining an emulsion;

[0053] (S4), adding a surface tension regulator and other additives to the emulsion, and stirring to obtain a high temperature resistant organosilicon defoamer.

[0054] Example 2

[0055] A high temperature resistant organic silicon defoamer comprises the following raw materials in parts by weight: 20 parts of modified polysiloxane, 1 part of emulsifier, 0.5 parts of surface tension regulator, 0.8 parts of other auxiliary agents and 40 parts of solvent.

[0056] The preparation method of each modified polysiloxane comprises the following steps:

[0057] (R1), take 100 parts of dimethyldimethoxysilane, 20 parts of methylphenylsiloxane, 8 parts of cyclic siloxane monomer, 1 part of hydrolysis catalyst, 5 parts of modifier, 100 parts of extractant and 50 parts of water by weight, and set aside;

[0058] (R2), adding dimethyldimethoxysilane and a hydrolysis catalyst to water, mixing evenly, heating to 80°C for reaction for 4 hours, removing impurities by reduced pressure distillation, and then reacting at 75°C for 2 hours to obtain oligosiloxane;

[0059] (R3), adding methylphenylsiloxane, cyclic siloxane monomer and modifier to the oligosiloxane, mixing evenly, reacting at 75° C. for 6 h, cooling, and obtaining a mixed product;

[0060] (R4), adding an extractant to the mixed product, mixing and letting stand, taking the organic phase, and removing the extractant by vacuum distillation to obtain a modified polysiloxane.

[0061] The cyclic siloxane monomer is octamethylcyclotetrasiloxane; the modifier is prepared by mixing aluminum isopropoxide and n-butyl titanate in a molar ratio of 1:1.

[0062] The hydrolysis catalyst is glacial acetic acid, and the extractant is acetylacetone.

[0063] The emulsifier is sorbitan monooleate polyoxyethylene ether.

[0064] The surface tension regulator is a fatty amine polyoxyethylene ether and a carboxylate anionic fluorocarbon surfactant. FSA is mixed in a weight ratio of 3:0.001.

[0065] Each part of the other adjuvants includes 0.3 parts of stabilizers and 0.5 parts of thickeners.

[0066] The stabilizer is a mixture of polyvinyl alcohol and sodium polyacrylate in a weight ratio of 1:3; the thickener is a mixture of carboxymethyl cellulose and hydroxypropyl methyl cellulose in a weight ratio of 1:6.

[0067] The solvent is deionized water.

[0068] The preparation method of the high temperature resistant organosilicon defoamer comprises the following steps:

[0069] (S1), taking modified polysiloxane, emulsifier, surface tension regulator, other additives and solvent according to weight parts for later use;

[0070] (S2), uniformly mixing the modified polysiloxane and the emulsifier to obtain a mixture;

[0071] (S3), adding a solvent to the mixture, stirring, and obtaining an emulsion;

[0072] (S4), adding a surface tension regulator and other additives to the emulsion, and stirring to obtain a high temperature resistant organosilicon defoamer.

[0073] Example 3

[0074] A high temperature resistant organic silicon defoamer comprises the following raw materials in parts by weight: 50 parts of modified polysiloxane, 10 parts of emulsifier, 2 parts of surface tension regulator, 8 parts of other auxiliary agents and 60 parts of solvent.

[0075] The preparation method of each modified polysiloxane comprises the following steps:

[0076] (R1), take 100 parts of dimethyldimethoxysilane, 30 parts of methylphenylsiloxane, 12 parts of cyclic siloxane monomer, 2 parts of hydrolysis catalyst, 8 parts of modifier, 100 parts of extractant and 80 parts of water by weight, and set aside;

[0077] (R2), adding dimethyldimethoxysilane and a hydrolysis catalyst to water, mixing evenly, heating to 95°C for reaction for 2h, removing impurities by reduced pressure distillation, and then reacting at 85°C for 1h to obtain oligosiloxane;

[0078] (R3), adding methylphenylsiloxane, cyclic siloxane monomer and modifier to the oligosiloxane, mixing evenly, reacting at 85° C. for 4 h, cooling, and obtaining a mixed product;

[0079] (R4), adding an extractant to the mixed product, mixing and letting stand, taking the organic phase, and removing the extractant by vacuum distillation to obtain a modified polysiloxane.

[0080] The cyclic siloxane monomer is octamethylcyclotetrasiloxane; the modifier is prepared by mixing aluminum isopropoxide and n-butyl titanate in a molar ratio of 1:3.

[0081] The hydrolysis catalyst is glacial acetic acid, and the extractant is acetylacetone.

[0082] The emulsifier is polyoxyethylene sorbitan monostearate.

[0083] The surface tension regulator is a fatty amine polyoxyethylene ether and a carboxylate anionic fluorocarbon surfactant. FSA is mixed in a weight ratio of 3:0.003.

[0084] Each part of the other auxiliary agents includes 5 parts of stabilizers and 3 parts of thickeners.

[0085] The stabilizer is a mixture of polyvinyl alcohol and sodium polyacrylate in a weight ratio of 1:3; the thickener is a mixture of carboxymethyl cellulose and hydroxypropyl methyl cellulose in a weight ratio of 1:6.

[0086] The solvent is deionized water.

[0087] The preparation method of the high temperature resistant organosilicon defoamer comprises the following steps:

[0088] (S1), taking modified polysiloxane, emulsifier, surface tension regulator, other additives and solvent according to weight parts for later use;

[0089] (S2), uniformly mixing the modified polysiloxane and the emulsifier to obtain a mixture;

[0090] (S3), adding a solvent to the mixture, stirring, and obtaining an emulsion;

[0091] (S4), adding a surface tension regulator and other additives to the emulsion, and stirring to obtain a high temperature resistant organosilicon defoamer.

[0092] Example 4

[0093] A high temperature resistant organic silicon defoamer comprises the following raw materials in parts by weight: 40 parts of modified polysiloxane, 6 parts of emulsifier, 1.2 parts of surface tension regulator, 3 parts of other auxiliary agents and 55 parts of solvent.

[0094] The preparation method of each modified polysiloxane comprises the following steps:

[0095] (R1), take 100 parts of dimethyldimethoxysilane, 26 parts of methylphenylsiloxane, 9 parts of cyclic siloxane monomer, 1.5 parts of hydrolysis catalyst, 6 parts of modifier, 100 parts of extractant and 70 parts of water by weight, and set aside;

[0096] (R2), adding dimethyldimethoxysilane and a hydrolysis catalyst to water, mixing evenly, heating to 88°C for reaction for 3 hours, removing impurities by reduced pressure distillation, and then reacting at 78°C for 1.8 hours to obtain oligosiloxane;

[0097] (R3), adding methylphenylsiloxane, cyclic siloxane monomer and modifier to the oligosiloxane, mixing evenly, reacting at 78° C. for 5.3 h, cooling, and obtaining a mixed product;

[0098] (R4), adding an extractant to the mixed product, mixing and letting stand, taking the organic phase, and removing the extractant by vacuum distillation to obtain a modified polysiloxane.

[0099] The cyclic siloxane monomer is octamethylcyclotetrasiloxane; the modifier is prepared by mixing aluminum isopropoxide and n-butyl titanate in a molar ratio of 1:2.

[0100] The hydrolysis catalyst is glacial acetic acid, and the extractant is acetylacetone.

[0101] The emulsifier is polyoxyethylene sorbitan monostearate.

[0102] The surface tension regulator is a fatty amine polyoxyethylene ether and a carboxylate anionic fluorocarbon surfactant. FSA is mixed in a weight ratio of 3:0.002.

[0103] Each part of the other auxiliary agents includes 3 parts of stabilizer and 1.8 parts of thickener.

[0104] The stabilizer is a mixture of polyvinyl alcohol and sodium polyacrylate in a weight ratio of 1:3; the thickener is a mixture of carboxymethyl cellulose and hydroxypropyl methyl cellulose in a weight ratio of 1:6.

[0105] The solvent is deionized water.

[0106] The preparation method of the high temperature resistant organosilicon defoamer comprises the following steps:

[0107] (S1), taking modified polysiloxane, emulsifier, surface tension regulator, other additives and solvent according to weight parts for later use;

[0108] (S2), uniformly mixing the modified polysiloxane and the emulsifier to obtain a mixture;

[0109] (S3), adding a solvent to the mixture, stirring, and obtaining an emulsion;

[0110] (S4), adding a surface tension regulator and other additives to the emulsion, and stirring to obtain a high temperature resistant organosilicon defoamer.

[0111] Comparative Example 1

[0112] The difference between this comparative example and Example 1 is:

[0113] A silicone defoamer comprises the following raw materials in parts by weight: 35 parts of polydimethylsiloxane, 5 parts of emulsifier, 1 part of surface tension regulator, 4 parts of other additives and 50 parts of solvent.

[0114] The polydimethylsiloxane is selected from polydimethylsiloxane 9016-00-6 produced by Ecolab Chemicals.

[0115] The cyclic siloxane monomer is octamethylcyclotetrasiloxane; the modifier is prepared by mixing aluminum isopropoxide and n-butyl titanate in a molar ratio of 1:2.

[0116] The hydrolysis catalyst is glacial acetic acid, and the extractant is acetylacetone.

[0117] The emulsifier is polyoxyethylene sorbitan monostearate.

[0118] The surface tension regulator is a fatty amine polyoxyethylene ether and a carboxylate anionic fluorocarbon surfactant. FSA is mixed in a weight ratio of 3:0.002.

[0119] Each part of the other auxiliary agents includes 3 parts of stabilizers and 2 parts of thickeners.

[0120] The stabilizer is a mixture of polyvinyl alcohol and sodium polyacrylate in a weight ratio of 1:3; the thickener is a mixture of carboxymethyl cellulose and hydroxypropyl methyl cellulose in a weight ratio of 1:6.

[0121] The solvent is deionized water.

[0122] The preparation method of the high temperature resistant organosilicon defoamer comprises the following steps:

[0123] (S1), taking polydimethylsiloxane, emulsifier, surface tension regulator, other additives and solvent according to weight parts, and setting aside;

[0124] (S2), mixing the polydimethylsiloxane and the emulsifier uniformly to obtain a mixture;

[0125] (S3), adding a solvent to the mixture, stirring, and obtaining an emulsion;

[0126] (S4), adding a surface tension regulator and other additives to the emulsion, and stirring to obtain an organosilicon defoamer.

[0127] Comparative Example 2

[0128] The difference between this comparative example and Example 1 is:

[0129] The preparation method of each modified polysiloxane comprises the following steps:

[0130] (R1), take 100 parts of dimethyldimethoxysilane, 28 parts of methylphenylsiloxane, 13 parts of cyclic siloxane monomer, 1.5 parts of hydrolysis catalyst, 100 parts of extraction agent and 65 parts of water by weight, and set aside;

[0131] (R2), adding dimethyldimethoxysilane and a hydrolysis catalyst to water, mixing evenly, heating to 90°C for reaction for 3 hours, removing impurities by reduced pressure distillation, and then reacting at 80°C for 1.5 hours to obtain oligosiloxane;

[0132] (R3), adding methylphenylsiloxane and cyclic siloxane monomers to the oligosiloxane, mixing evenly, reacting at 80° C. for 5 h, cooling, and obtaining a mixed product;

[0133] (R4), adding an extractant to the mixed product, mixing and letting stand, taking the organic phase, and removing the extractant by vacuum distillation to obtain a modified polysiloxane.

[0134] Comparative Example 3

[0135] The difference between this comparative example and Example 1 is:

[0136] The preparation method of each modified polysiloxane comprises the following steps:

[0137] (R1), take 100 parts of dimethyldimethoxysilane, 35 parts of cyclic siloxane monomer, 1.5 parts of hydrolysis catalyst, 6 parts of modifier, 100 parts of extractant and 65 parts of water by weight, and set aside;

[0138] (R2), adding dimethyldimethoxysilane and a hydrolysis catalyst to water, mixing evenly, heating to 90°C for reaction for 3 hours, removing impurities by reduced pressure distillation, and then reacting at 80°C for 1.5 hours to obtain oligosiloxane;

[0139] (R3), adding methylphenylsiloxane, cyclic siloxane monomer and modifier to the oligosiloxane, mixing evenly, reacting at 80° C. for 5 h, cooling, and obtaining a mixed product;

[0140] (R4), adding an extractant to the mixed product, mixing and letting stand, taking the organic phase, and removing the extractant by vacuum distillation to obtain a modified polysiloxane.

[0141] Comparative Example 4

[0142] The difference between this comparative example and Example 1 is:

[0143] The surface tension regulator is a mixture of fatty amine polyoxyethylene ether and polyether modified silicone oil H-204 in a weight ratio of 3:0.002.

[0144] Comparative Example 5

[0145] The invention discloses an organosilicon defoamer, which is a polydimethylsiloxane defoamer.

[0146] The polydimethylsiloxane defoamer is selected from JY-810.

[0147] Performance Testing

[0148] The organosilicon defoamers of Examples 1-4 and Comparative Examples 1-5 were taken to test their stability, defoaming performance and antifoaming performance at different temperatures, and the test conditions were as follows.

[0149] Sample: Take the organosilicon defoamers of Examples 1-4 and Comparative Examples 1-5, add deionized water to dilute them respectively (the volume ratio of the added deionized water to the organosilicon defoamer is 1:2), sterilize them at 121° C., and cool them to obtain samples;

[0150] Foaming liquid: 0.5 wt % nonylphenol polyoxyethylene (10) ether-water solution and 0.5 wt % sodium dodecylbenzene sulfonate-water solution are mixed, and the system temperature is adjusted to 80° C. (high temperature) in a constant temperature water bath to obtain a foaming liquid.

[0151] (1) Stability test

[0152] Use two 10mL graduated centrifuge test tubes to measure 8mL of the sample respectively, place them symmetrically in a 80-2 low-speed electric centrifuge, and rotate continuously at a speed of 3000r / min for 15min. Take out the test tubes, read the volume of the stratified liquid, and take the arithmetic mean of the two measured values ​​as the measurement result.

[0153] (2) Defoaming performance

[0154] Use a 100mL stoppered measuring cylinder to take 50mL of the foaming liquid, add 0.05g of the sample, and keep the temperature in a water bath at 25℃ and 80℃ respectively. Cover the bottle with the stopper, and shake the measuring cylinder vertically up and down 10 times at a frequency of 2 times / s and an amplitude of (30-35) cm. Let it stand and start timing with a stopwatch, recording the time taken for the foam to disappear and the liquid surface to appear.

[0155] (3) Antifoaming performance

[0156] Use a lubricating oil (defoaming agent) foam property tester that meets the test requirements of GB / T 12579. Turn on and debug the foam property tester, and test the air flow rate at 100mL / min. Take 100mL of foaming liquid, add 0.1g of sample to the foaming liquid, stir evenly, and then pour it into a clean bubbler measuring cylinder, and keep the temperature constant at 25℃ and 80℃ respectively. Turn on the flow pump, start the test, record the foam volume (mL) after 30min of air blowing, and express the result as the foam volume corresponding to 30min of air blowing.

[0157] The test results are shown in Table 1:

[0158] Table 1

[0159]

[0160] It can be seen from Table 1 above that the high temperature resistant organosilicon defoamer of the present invention has excellent high temperature resistance, weather resistance and chemical stability, can maintain the stability of the defoamer in a high temperature environment, effectively destroy the stability of the foam, and enable the gas and liquid to fully contact, thereby achieving the defoaming effect, and the high temperature resistant organosilicon defoamer can spread on the surface of sewage to form a very thin and uniform molecular film, which not only has the effect of reducing surface tension, but also can prevent bubble formation, thereby improving the efficiency of the entire treatment process, and is particularly suitable for the defoaming and anti-foaming needs of the high temperature treatment process of sewage.

[0161] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A high temperature resistant silicone defoamer, characterized in that: The invention comprises the following raw materials in parts by weight: Modified polysiloxane 20-50 parts Emulsifier 1-10 parts Surface tension regulator 0.1-2 parts Other additives 0.2-8 parts 40-60 parts of solvent; The surface tension regulator is a mixture of fatty amine polyoxyethylene ether and carboxylate anionic fluorocarbon surfactant in a weight ratio of 3:0.001-0.003; The preparation method of each modified polysiloxane comprises the following steps: (R1), take 100 parts of dimethyldimethoxysilane, 20-30 parts of methylphenylsiloxane, 8-12 parts of cyclic siloxane monomer, 1-2 parts of hydrolysis catalyst, 5-8 parts of modifier, 100 parts of extractant and 50-80 parts of water by weight, and set aside; (R2), add dimethyldimethoxysilane and a hydrolysis catalyst to water and mix evenly, heat to 80-95°C and react for 2-4 hours, remove impurities by vacuum distillation, and then react at 75-85°C for 1-2 hours to obtain oligosiloxane; (R3), adding methylphenylsiloxane, cyclic siloxane monomer and modifier to oligosiloxane, mixing evenly, reacting at 75-85°C for 4-6h, cooling, and obtaining a mixed product; (R4), adding an extractant to the mixed product, mixing and letting the mixture stand, taking an organic phase, and removing the extractant by vacuum distillation to obtain a modified polysiloxane; The cyclic siloxane monomer is dimethyl cyclosiloxane or octamethyl cyclotetrasiloxane; the modifier is a mixture of aluminum isopropoxide and n-butyl titanate in a molar ratio of 1:1-3; The hydrolysis catalyst is glacial acetic acid, and the extractant is xylene or acetylacetone.

2. A high temperature resistant silicone defoamer according to claim 1, characterized in that: The emulsifier is at least one of polyoxyethylene sorbitan monostearate, sorbitan monooleate polyoxyethylene ether and sodium dodecylbenzene sulfonate.

3. A high temperature resistant silicone defoamer according to claim 1, characterized in that: Each part of the other auxiliary agents includes 0.1-5 parts of stabilizers and 0.1-3 parts of thickeners.

4. The high temperature resistant silicone defoamer according to claim 3, characterized in that: The stabilizer is polyvinyl alcohol and / or sodium polyacrylate; the thickener is carboxymethyl cellulose and / or hydroxypropyl methyl cellulose.

5. The high temperature resistant silicone defoamer according to claim 1, characterized in that: The solvent is deionized water.

6. A method for preparing a high temperature resistant organosilicon defoamer according to any one of claims 1 to 5, characterized in that: The steps include: (S1), taking modified polysiloxane, emulsifier, surface tension regulator, other additives and solvent according to weight parts and setting aside; (S2), uniformly mixing the modified polysiloxane and the emulsifier to obtain a mixture; (S3), adding a solvent to the mixture, stirring, and obtaining an emulsion; (S4), adding a surface tension regulator and other additives to the emulsion, and stirring to obtain a high temperature resistant silicone defoaming agent.

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