High-stability defoaming agent and preparation method thereof

Abstract

The invention provides a high-stability defoaming agent and a preparation method thereof, and belongs to the technical field of defoaming agents. The defoaming agent is prepared from 40 to 60 parts of polyether modified organic silicon, 130 to 170 parts of branched polyether ester, 270 to 330 parts of silicon factice, 14 to 18 parts of other auxiliary agents and 430 to 530 parts of water; the polyether modified organic silicon is obtained by carrying out hydrosilylation reaction on allyl polyoxyalkyl ether and hydrogen-containing silicone oil under the catalysis of chloroplatinic acid; the allyl polyoxyalkyl ether is prepared by carrying out polymerization reaction on allyl alcohol and alkylene oxide; the branched polyether ester is obtained by carrying out esterification reaction on branched polyoxyalkyl ether and fatty acid under the action of an acid catalyst; and the branched polyoxyalkyl ether is prepared by carrying out polymerization reaction on polyfunctional polyol and alkylene oxide. The defoaming agent disclosed by the invention is stable in storage at a high temperature, can maintain a good defoaming speed in a strong acid and alkali environment, and can maintain relatively strong foam inhibition activity.

Description

Technical Field

[0001] This invention belongs to the field of defoamer technology, specifically relating to a highly stable defoamer and its preparation method. Background Technology

[0002] Excessive foam is easily generated during industrial production. Improper foam control can disrupt the stable execution of production processes and the normal operation of equipment, leading to decreased product yield and deteriorated quality. Therefore, defoamers are needed to effectively control foam. Among various defoamers, polyether-modified silicone defoamers are a preferred choice in industrial applications due to their broad applicability and high defoaming efficiency. However, existing polyether-modified silicone defoamers still have many technical shortcomings in preparation, storage, and practical application, limiting their effectiveness and applicability.

[0003] Specifically, the core problems of existing polyether-modified silicone defoamers are concentrated in the following aspects: First, in order to improve defoaming performance, existing technologies often optimize the system through cross-linking, compounding, etc. However, the intercalation and bonding stability of polyether segments and hydrophobic particles (such as silica) in polyether-modified silicone is insufficient. Under harsh industrial environments such as high temperature and strong acid and alkali, demulsification and oil floating phenomena are prone to occur, resulting in poor defoaming durability and difficulty in meeting the long-term stable foam control requirements. Second, silicone itself is water-insoluble. The defoaming particles of existing polyether-modified silicone defoamers are prone to agglomeration in the foaming medium. Small particles gradually agglomerate into large particles, and then lose their defoaming function. Although some technologies have attempted to improve dispersibility by adjusting the system, the effect is limited. Third, some existing technologies prepare emulsion-type defoamers by adding surfactants to polyether-modified silicone. However, there are problems such as short shelf life of emulsions and easy particle agglomeration and precipitation, resulting in poor product performance stability and inability to adapt to various industrial scenarios.

[0004] The aforementioned defects make it difficult for existing polyether-modified silicone defoamers to simultaneously achieve high efficiency, stability, and compatibility. Therefore, developing a polyether-modified silicone defoamer with more comprehensive performance and wider applicability has significant practical and industrial value. Summary of the Invention

[0005] The purpose of this invention is to provide a highly stable defoamer that is stable at high temperatures, does not separate into layers, does not cause oil floating, and can maintain good defoaming speed and strong antifoaming activity in strongly acidic or alkaline environments.

[0006] The objective of this invention is achieved through the following technical solution: A highly stable defoamer, wherein the defoamer comprises the following components in parts by weight: 40-60 parts of polyether-modified organosilicon, 130-170 parts of branched polyether ester, 270-330 parts of silicone paste, 14-18 parts of other additives, and 430-530 parts of water; The polyether-modified organosilicon is obtained by hydrosilylation reaction of allyl polyoxyalkyl ether and hydrogen-containing silicone oil under the catalysis of chloroplatinic acid; the allyl polyoxyalkyl ether is obtained by polymerization reaction of allyl alcohol and epoxy alkane; the hydrogen-containing silicone oil has a hydrogen content of 0.05% to 0.45% and a molecular weight of 200 to 4000. The branched polyether ester is obtained by esterification of branched polyoxyalkyl ether with fatty acid under the action of an acidic catalyst; the branched polyoxyalkyl ether is obtained by polymerization of polyfunctional polyol with epoxy alkane, wherein the polyfunctional polyol is one or more of glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose.

[0007] In this invention, the other additives include 7-9 parts of thickener and 7-9 parts of preservative.

[0008] In this invention, the allyl polyoxyalkyl ether has a molecular weight of 300-1500 and is prepared by the following method: allyl alcohol and alkyl oxidase react at 110-130°C for 4-10 hours under the action of a catalyst and a reaction pressure ≤0.3 MPa. After the reaction, phosphoric acid is added for neutralization, a refining agent is added for adsorption, and the mixture is filtered after vacuum distillation to obtain the allyl polyoxyalkyl ether. The alkyl oxidase is a mixture of ethylene oxide, propylene oxide, and butane oxide, and the molar ratio of alkyl oxidase to allyl alcohol is 1-20:1. The catalyst is potassium hydroxide, sodium methoxide, or potassium methoxide, and its amount is 0.05-0.5% of the total mass of allyl alcohol and alkyl oxidase. The refining agent is magnesium silicate, and its amount is 0.2%-1% of the mass of the allyl polyoxyalkyl ether.

[0009] In this invention, in the hydrosilylation reaction, the molar ratio of the double bond in the allyl polyoxyalkyl ether to the Si-H bond in the hydrogen-containing silicone oil is 1 to 1.5:1, the amount of chloroplatinic acid catalyst added per kilogram of reactants is 3 to 20 mg, the reaction temperature is 80 to 120°C, and the reaction time is 1 to 5 min; the reactants are allyl polyoxyalkyl ether and hydrogen-containing silicone oil.

[0010] In this invention, the branched polyoxyalkylene ether has a molecular weight of 1000-6000 and is prepared by the following method: a polyfunctional polyol and an epoxy alkane are reacted at 110-130°C for 8-12 hours under the action of a catalyst and a reaction pressure ≤0.3 MPa. After the reaction, phosphoric acid is added for neutralization, a refining agent is added for adsorption, and the mixture is filtered after vacuum distillation to obtain the branched polyoxyalkylene ether. The epoxy alkane is ethylene oxide, propylene oxide, or butane oxide, and the molar ratio of epoxy alkane to polyfunctional polyol is 1-30:0.5. The catalyst is potassium hydroxide, sodium methoxide, or potassium methoxide, and the amount used is 0.05-0.5% of the total mass of the polyfunctional polyol and epoxy alkane.

[0011] In this invention, the branched polyether ester is prepared by the following method: fatty acids and the branched polyoxyalkylene ether are reacted with a catalyst at a reaction temperature of 140-180°C and a reaction pressure of 0.07-0.08 MPa, with nitrogen purging maintained, for 4-8 hours to obtain the branched polyether ester; the molar ratio of the fatty acid to the branched polyoxyalkylene ether is 3-6:1; the catalyst is one or more of sulfuric acid, p-toluenesulfonic acid, stannous octoate, or monobutyltin oxide, and the amount used is 0.1-1% of the total mass of the fatty acid and the branched polyoxyalkylene ether.

[0012] In this invention, the thickener is selected from one or more of hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0013] In this invention, the preservative is composed of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one; the mass ratio of 5-chloro-2-methyl-4-isothiazolin-3-one to 2-methyl-4-isothiazolin-3-one is 5: (1-25).

[0014] The present invention also provides a method for preparing the highly stable defoamer, comprising the following steps: (1) Hydrophobic fumed silica and dimethyl silicone oil are refluxed at 100-160℃ for 2-5 hours to obtain silicone oil paste; (2) Add polyether-modified organosilicon to the silicone grease, mix evenly, add distilled water dropwise while stirring to cause the phase inversion, and obtain an oil-in-water emulsion. After sterilization, the defoamer is obtained.

[0015] In this invention, in step (1), the mass ratio of hydrophobic fumed silica to dimethyl silicone oil is 1:18-20; in step (2), branched polyether ester, thickener and preservative are added during the process of adding distilled water.

[0016] Beneficial Effects: During the research process, the inventors discovered that when the epoxide portion was incorporated into the allyl polyether during the preparation of polyether-modified organosilicon, the defoaming and foam-suppressing abilities of the prepared polyether-modified organosilicon were greatly enhanced in strongly acidic and alkaline environments. Simultaneously, it was found that polyether-modified organosilicon was prone to aggregation and precipitation during long-term high-temperature storage. Through extensive experimentation, the applicant unexpectedly discovered that the addition of branched polyether esters could complement the polyether-modified organosilicon, compensating for the poor compatibility between the polyether-modified organosilicon and the system, showing promising application prospects in the field of defoamers. The defoamer composition of this invention effectively solves the high-temperature stability problem existing in the prior art, does not cause stratification or oil floating, and exhibits excellent defoaming and foam-suppressing performance in strongly acidic and alkaline environments. Attached Figure Description

[0017] Figure 1 In the image, 'a' represents hydrogen-containing silicone oil, and 'b' represents the Fourier transform infrared spectrum of the polyether-modified organosilicon prepared in Example 1. The horizontal axis represents wavelength, and the unit is cm. -1 The vertical axis represents transmittance, and the unit is _____.

[0018] Figure 2 The NMR spectrum of polyether-modified organosilicon is shown in 1H NMR. The horizontal axis represents chemical shift, and the unit is ppm. Detailed Implementation

[0019] The present invention will be further described in detail below through embodiments, but the scope of protection of the present invention is not limited to the scope shown in the embodiments.

[0020] Example 1: Preparation of the high-stability defoamer of the present invention 1. Preparation of allyl polyoxyalkyl ethers 264 g of ethylene oxide (6 mol), 348 g of propylene oxide (i.e., propylene oxide, 6 mol), and 280 g of 1,2-epoxybutane (4 mol) were accurately weighed and placed in a storage tank and mixed thoroughly to obtain mixed epoxy alkane. 58 g of allyl alcohol (CH2=CHCH2OH, 1 mol) and 2.4 g of potassium methoxide were added to a reaction vessel, and the mixture was purged with nitrogen three times. Then, the mixed epoxy alkane was introduced, maintaining the temperature inside the vessel at 120 °C and the pressure at 0.3 MPa for 5 hours. After the feeding was completed, the mixture was aged at 125 °C and 0.3 MPa for 3 hours. After the aging reaction, unreacted epoxy alkane was removed under vacuum to obtain 941 g of crude allyl polyoxyalkylene ether. Then, 40g of distilled water and 4.5g of phosphoric acid were added to the crude allyl polyoxyalkyl ether, and the mixture was neutralized to neutrality under stirring. 3g of magnesium silicate was added, and the mixture was stirred for 1 hour. The mixture was then distilled under reduced pressure at 110℃ and a vacuum of 0.098MPa for 3 hours to remove moisture. The residue was removed by filtration to obtain allyl polyoxyalkyl ether. The hydroxyl value of the allyl polyoxyalkyl ether was determined to be 59.58 mg KOH / g by the phthalic anhydride-pyridine method (GB / T 12008.3-2009), the number-average molecular weight was 942 g / mol, and the yield was 99.05%.

[0021] 2. Preparation of polyether-modified organosilicon 650g of allyl polyoxyalkyl ether (prepared in Title 1 of this embodiment), 350g of hydrogen-containing silicone oil, and 5mg of chloroplatinic acid (added in the form of a 1% chloroplatinic acid isopropanol solution) were added to the reactor. The temperature was raised to 100°C. After reacting at 100°C for 2 minutes, the reaction system changed from a turbid liquid to a colorless and transparent liquid, indicating that the reaction was complete. Then, the system was distilled under reduced pressure (vacuum degree of 0.098MPa) at 100°C for 30 minutes to remove low-boiling substances, thus obtaining polyether-modified organosilicon.

[0022] The hydrogen-containing silicone oil was purchased from Dow Chemical, and its structural formula is as follows: Si(CH3)3O[Si(CH3)2O] 38 [Si(CH3)HO]6Si(CH3)3, with a number-average molecular weight of 3220 g / mol, has the following structural formula: Me represents a methyl group.

[0023] Figure 1 The figures show the Fourier transform infrared (FTIR) spectra of hydrogen-containing silicone oil and the polyether-modified organosilicon prepared in this embodiment. In the figure, a represents the hydrogen-containing silicone oil, and b represents the polyether-modified organosilicon. Figure 1 As can be seen from this, hydrogen-containing silicone oil at 2156 cm -1There is a strong Si-H bond characteristic absorption peak at this location, while the Si-H bond characteristic absorption peak of polyether modified organosilicon has completely disappeared at this location, indicating that the Si-H bonds in the hydrogen-containing silicone oil and the double bonds in the allyl polyoxyalkyl ether have completely undergone hydrosilylation reaction. Figure 2 The 1H NMR spectrum of polyether-modified organosilicon is shown. 1 1H NMR data (CDCl3 as solvent, TMS as internal standard): 3.243–3.675 (m, 64H, -OCH2-), 2.7 (s, H, -OH), 1.394–1.511 (m, 10H, -OCH-), 1.017–1.085 (m, 18H, -CH3), 0.899–0.843 (m, 12H, -CH3), -0.071–0.072 (m, 36H, Si-CH3).

[0024] 3. Preparation of branched polyoxyalkyl ethers Accurately weigh 1044g of propylene oxide (i.e., propylene oxide, 18mol) and 280g of 1,2-epoxybutane (4mol) and place them in a storage tank, then mix thoroughly to obtain mixed epoxy alkane. Add 68g (0.5mol) of pentaerythritol and 4g of KOH to the reactor, purge with nitrogen three times, and then begin introducing the mixed epoxy alkane. During the feeding process, maintain the reactor temperature at 120℃ and the pressure at 0.3MPa for 10 hours. After the feeding is complete, age the reactor at 125℃ and 0.3MPa for 3 hours. After the aging reaction is complete, introduce 220g of ethylene oxide (5mol), maintaining the reactor temperature at 120℃ and the pressure at 0.3MPa for 1 hour. After the feeding is complete, age the reactor at 125℃ and 0.3MPa for 3 hours. After the aging reaction was completed, unreacted epoxyalkane was removed under vacuum to obtain 1590g of crude branched polyoxyalkylene ether. Then, 60g of distilled water and 8g of phosphoric acid were added to the crude branched polyoxyalkylene ether, and the mixture was neutralized to neutrality under stirring. 5g of magnesium silicate was added, and stirring continued for 1 hour. The mixture was then distilled under reduced pressure at 110℃ and a vacuum of 0.098MPa for 3 hours to remove moisture. The residue was removed by filtration to obtain the branched polyoxyalkylene ether. The hydroxyl value of the branched polyoxyalkylene ether was determined to be 74.45 mg KOH / g by the phthalic anhydride-pyridine method (GB / T 12008.3-2009), the number-average molecular weight was 3014 g / mol, and the yield was 98.42%.

[0025] 4. Preparation of branched polyether esters 1507 g of branched polyoxyalkylene ether (prepared in Title 3 of this embodiment, 0.5 mol), 610 g of erucic acid (cis-13-docosahexaenoic acid, 1.8 mol), and 4 g of monobutyltin oxide (catalyst, butyl type n-butyl, purchased from Shanghai Gaoming Chemical Co., Ltd.) were added to the reactor. After nitrogen purging three times, the esterification reaction was carried out at 155 °C, under a vacuum of 0.07 MPa ~ 0.08 MPa, and with nitrogen purging maintained (flow rate 0.3 L / min) for 5 h, yielding 2010 g of branched polyether ester. The hydroxyl value of the branched polyether ester was determined to be 3.64 mg KOH / g by the phthalic anhydride-pyridine method (GB / T 12008.3-2009), and the acid value of the branched polyether ester was determined to be 0.33 mg KOH / g by the acid-base titration method (GB / T12008.5-2010), with a yield of 99.17%.

[0026] 5. Preparation of the defoamer of the present invention (1) Add 15g of hydrophobic fumed silica (purchased from Evonik Degussa, AEROSIL R974, BET specific surface area 170±20m²) to a three-necked flask. 2 285 g of dimethyl silicone oil (purchased from Dow Corning, PMX-200, kinematic viscosity of 1000 cst at 25°C) and 285 g of dimethyl silicone oil (purchased from Dow Corning, PMX-200, kinematic viscosity of 1000 cst at 25°C) were refluxed at 125°C for 3 h and cooled to room temperature to obtain silicone paste.

[0027] (2) Add 50g of polyether-modified organosilicon (prepared in Title 2 of this embodiment) to the silicone grease obtained in step (1), mix evenly, and then add 484g of distilled water dropwise while stirring at high speed (3000rpm) to cause a phase reversal. When the distilled water has been added to 1 / 2 of the total amount, add 150g of branched polyether ester (prepared in Title 4 of this embodiment), 8g of thickener (hydroxyethyl cellulose), and 8g of preservative (a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one in a mass ratio of 5:10). After all the distilled water has been added, continue stirring for 30min to form a stable oil-in-water (O / W) emulsion.

[0028] (3) The water-in-oil emulsion was sterilized at 120°C and 0.1 MPa for 30 min and then cooled to obtain the defoamer of the present invention.

[0029] Comparative Example 2 Preparation of control defoamer A: It was prepared according to the preparation method of the defoamer of the present invention in Example 1, except that 150g of branched polyether ester was not added.

[0030] Comparative Example 3 Preparation of control defoamer B: It was prepared according to the preparation method of the defoamer of the present invention in Example 1, except that 150g of branched polyoxyalkyl ether (prepared in Example 1, title 3) was used instead of 150g of branched polyether ester.

[0031] Comparative Example 4 1. Preparation of allyl polyoxyalkyl ethers 264 g of ethylene oxide (6 mol) and 638 g of propylene oxide (i.e., propylene oxide, 11 mol) were accurately weighed and placed in a storage tank and mixed thoroughly to obtain mixed epoxy alkane. 58 g of allyl alcohol (CH2=CHCH2OH, 1 mol) and 2.4 g of potassium methoxide were added to a reaction vessel, and the mixture was purged with nitrogen three times. Then, the mixed epoxy alkane was introduced, maintaining the temperature inside the vessel at 120 °C and the pressure at 0.3 MPa for 5 hours. After the feeding was completed, the mixture was aged at 125 °C and 0.3 MPa for 3 hours. After the aging reaction, unreacted epoxy alkane was removed by vacuum to obtain 950 g of crude allyl polyoxyalkylene ether. Then, 40g of distilled water and 4.5g of phosphoric acid were added to the crude allyl polyoxyalkyl ether, and the mixture was neutralized to neutrality under stirring. 3g of magnesium silicate was added and stirred for 1 hour. The mixture was then distilled under reduced pressure at 110℃ and a vacuum of 0.098MPa for 3 hours to remove moisture. The residue was removed by filtration to obtain allyl polyoxyalkyl ether. The hydroxyl value of the allyl polyoxyalkyl ether was determined to be 59.26 mg KOH / g by the phthalic anhydride-pyridine method (GB / T 12008.3-2009), the number-average molecular weight was 947 g / mol, and the yield was 98.96%.

[0032] 2. Preparation of polyether-modified organosilicon 650g of allyl polyoxyalkyl ether (prepared in Comparative Example 4, Title 1), 350g of hydrogen-containing silicone oil (structure same as in Example 1), and 5mg of chloroplatinic acid (added as a 1% chloroplatinic acid isopropanol solution) were added to the reactor. The temperature was raised to 100°C. After reacting at 100°C for 2 minutes, the reaction system changed from a turbid liquid to a colorless and transparent liquid, indicating that the reaction was complete. Then, the low-boiling substances were removed by vacuum distillation (vacuum degree of 0.098MPa) at 100°C for 30 minutes to obtain polyether-modified organosilicon.

[0033] 3. Preparation of control defoamer C The defoamer C was prepared according to the preparation method of the defoamer of the present invention in Example 1, except that 50g of polyether-modified organosilicon prepared in Comparative Example 4 (Title 2) was used instead of 50g of polyether-modified organosilicon prepared in Example 1.

[0034] Comparative Example 5 A method for preparing a polyether-modified polysiloxane defoamer according to patent number 202411348866.1, entitled "A Defoamer with Fast Dispersion, Low Cloud Point, High Temperature and High Pressure Resistance, and Resistance to Strong Acids and Alkalis": 250 g of prepared silicone paste, 50 g of spherical polysilsesquioxane, and 150 g of end-capped polyether-modified polysiloxane were homogenized until fully mixed. Then, 50 g of compounded polyether, 5 g of thickener, 5 g of sterilizing agent, and 125 g of water were added and stirred evenly. The mixture was then homogenized rapidly for another 30 minutes to obtain a homogeneous polyether-modified polysiloxane defoamer, designated as control defoamer D. The specific sources and preparation methods of each substance are the same as those in the same invention patent.

[0035] Performance testing Defoaming performance: The defoaming performance of the defoamers prepared in Example 1 and the comparative example on foaming solutions with pH values ​​of 2 and 12 was investigated. A 0.5 wt% nonylphenol polyoxyethylene (10) ether aqueous solution and a 0.5 wt% sodium dodecylbenzenesulfonate aqueous solution were mixed at a volume ratio of 1:1. The pH was adjusted to 2 and 12 respectively using 1 mol / L dilute sulfuric acid and 1 mol / L NaOH aqueous solution. The system temperature was adjusted to 80°C (high temperature) using a constant temperature water bath to obtain the foaming solution. 50 mL of the foaming solution was taken using a 100 mL stoppered graduated cylinder, and 0.05 g of defoamer was added. The solution was kept at a constant temperature of 80°C in a water bath, the stopper was closed, and the graduated cylinder was vertically shaken up and down 10 times at a frequency of 2 times / s and an amplitude of (30-35) cm. After standing, a stopwatch was used to record the time taken for the foam to disappear until the liquid surface appeared. Nonylphenol polyoxyethylene (10) ether refers to nonylphenol polyoxyethylene ether with an average degree of polymerization of 10.

[0036] Defoaming performance: The defoaming performance of each defoamer on foaming solutions with pH values ​​of 2 and 12 was investigated. The foaming solution used in the defoaming performance test was the same as that used in the defoaming performance test. A defoamer foam characteristic tester conforming to the requirements of GB / T 12579 was used. The foam characteristic tester was turned on and adjusted, and the test gas flow rate was set to 100 mL / min. 100 mL of foaming solution was taken, 0.1 g of defoamer was added to the foaming solution, stirred evenly, and then poured into a clean graduated cylinder of a bubbler. The temperature was kept constant at 80℃. The flow pump was turned on to introduce air for bubbling, and the test start time was recorded at the same time. During the bubbling process, the gas flow rate was kept stable at 100 mL / min. After bubbling for 30 min, the air supply was stopped immediately, and the foam volume (mL) in the graduated cylinder was recorded. The foam volume corresponding to 30 min of bubbling was used to represent the defoaming performance.

[0037] Stability test: Each defoamer was stored in an environment of 120℃ and the separation time was recorded to compare stability. The longer the separation time, the better the stability of the sample.

[0038] Table 1 Performance Test Results

[0039] The test results above show that the defoamer of this invention has excellent high-temperature resistance and acid / alkali resistance. It can maintain the stability of the defoamer in high-temperature and strong acid / alkali environments, effectively destroying the stability of foam and allowing gas and liquid to fully contact, thereby achieving the defoaming effect. Of particular note is that the defoamer of this invention maintains high foam suppression performance while also achieving a rapid defoaming speed.

Claims

1. A highly stable defoamer, characterized in that: The defoamer, by weight, comprises the following components: 40-60 parts of polyether-modified organosilicon, 130-170 parts of branched polyether ester, 270-330 parts of silicone paste, 14-18 parts of other additives, and 430-530 parts of water; The polyether-modified organosilicon is obtained by hydrosilylation reaction of allyl polyoxyalkyl ether and hydrogen-containing silicone oil under the catalysis of chloroplatinic acid; the allyl polyoxyalkyl ether is obtained by polymerization reaction of allyl alcohol and epoxy alkane; the hydrogen-containing silicone oil has a hydrogen content of 0.05% to 0.45% and a molecular weight of 200 to 4000. The branched polyether ester is obtained by esterification of branched polyoxyalkyl ether with fatty acid under the action of an acidic catalyst; the branched polyoxyalkyl ether is obtained by polymerization of polyfunctional polyol with epoxy alkane, wherein the polyfunctional polyol is one or more of glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose.

2. The high-stability defoamer according to claim 1, characterized in that... The other additives include 7-9 parts thickener and 7-9 parts preservative.

3. The high-stability defoamer according to claim 1 or 2, characterized in that... The allyl polyoxyalkyl ether has a molecular weight of 300–1500 and is prepared by the following method: allyl alcohol and alkyl oxidase react at 110–130°C for 4–10 h under the action of a catalyst and a reaction pressure ≤0.3 MPa. After the reaction, phosphoric acid is added for neutralization, a refining agent is added for adsorption, and the mixture is filtered after vacuum distillation to obtain the allyl polyoxyalkyl ether. The alkyl oxidase is a mixture of ethylene oxide, propylene oxide, and butane oxide, with a molar ratio of alkyl oxidase to allyl alcohol of 1–20:

1. The catalyst is potassium hydroxide, sodium methoxide, or potassium methoxide, and its amount is 0.05–0.5% of the total mass of allyl alcohol and alkyl oxidase. The refining agent is magnesium silicate, and its amount is 0.2%–1% of the mass of the allyl polyoxyalkyl ether.

4. The high-stability defoamer according to claim 3, characterized in that... In the hydrosilylation reaction, the molar ratio of the double bond in the allyl polyoxyalkyl ether to the Si-H bond in the hydrogen-containing silicone oil is 1 to 1.5:1, the amount of chloroplatinic acid catalyst added per kilogram of reactants is 3 to 20 mg, the reaction temperature is 80 to 120°C, and the reaction time is 1 to 5 min; the reactants are allyl polyoxyalkyl ether and hydrogen-containing silicone oil.

5. The high-stability defoamer according to claim 4, characterized in that... The branched polyoxyalkylene ether has a molecular weight of 1000-6000 and is prepared by the following method: a polyfunctional polyol and an epoxy alkane are reacted at 110-130°C for 8-12 hours under the action of a catalyst and a reaction pressure ≤0.3 MPa. After the reaction, phosphoric acid is added for neutralization, a refining agent is added for adsorption, and the mixture is filtered after vacuum distillation to obtain the branched polyoxyalkylene ether. The epoxy alkane is ethylene oxide, propylene oxide, or butane oxide, and the molar ratio of epoxy alkane to polyfunctional polyol is 1-30:0.

5. The catalyst is potassium hydroxide, sodium methoxide, or potassium methoxide, and the amount used is 0.05-0.5% of the total mass of the polyfunctional polyol and epoxy alkane.

6. The high-stability defoamer according to claim 5, characterized in that... The branched polyether ester is prepared by the following method: fatty acids and the branched polyoxyalkyl ether are reacted with a catalyst at a reaction temperature of 140-180℃ and a reaction pressure of 0.07MPa-0.08MPa, with nitrogen purging maintained, for 4-8 hours to obtain the branched polyether ester; the molar ratio of fatty acids to branched polyoxyalkyl ether is 3-6:1; the catalyst is one or more of sulfuric acid, p-toluenesulfonic acid, stannous octoate, or monobutyltin oxide, and the amount used is 0.1-1% of the total mass of fatty acids and branched polyoxyalkyl ether.

7. The high-stability defoamer and its preparation method according to claim 6, characterized in that... The thickener is selected from one or more of hydroxypropyl methylcellulose, hydroxyethyl methylcellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

8. The high-stability defoamer according to claim 7, characterized in that... The preservative is composed of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one; the mass ratio of 5-chloro-2-methyl-4-isothiazolin-3-one to 2-methyl-4-isothiazolin-3-one is 5: (1-25).

9. A method for preparing the highly stable defoamer according to any one of claims 1-8, characterized in that... Includes the following steps: (1) Hydrophobic fumed silica and dimethyl silicone oil are refluxed at 100-160℃ for 2-5 hours to obtain silicone oil paste; (2) Add polyether-modified organosilicon to the silicone grease, mix evenly, add distilled water dropwise while stirring to cause the phase inversion, and obtain an oil-in-water emulsion. After sterilization, the defoamer is obtained.

10. The preparation method according to claim 9, characterized in that... In step (1), the mass ratio of hydrophobic fumed silica to dimethyl silicone oil is 1:18-20; in step (2), branched polyether ester, thickener and preservative are added during the process of adding distilled water.

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