High temperature and high shear resistant system with high content organosilicon defoamer composition

Abstract

The application relates to the technical field of defoaming agent preparation, in particular to a high-content organic silicon defoaming agent composition for a high-temperature and high-shear system. The high-content organic silicon defoaming agent composition is prepared by the following steps: firstly, octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane and hydrogen-containing polymethylsiloxane are copolymerized to construct a methylphenyl polysiloxane skeleton; secondly, acetyl-terminated allyl epoxy oxirane / epoxy propane copolyether and allyl glycidyl ether are introduced step by step; then, the obtained product is sequentially reacted with N,N-diethyl-1,3-propanediamine, phenyl isocyanate, diisopropylamine and maleic anhydride to obtain a urea-based / esterified modified polysiloxane; finally, the urea-based / esterified modified polysiloxane is compounded with methylphenyl silicone oil, dimethyl silicone oil, hydrophobic fumed silica and precipitated silica to obtain the high-content organic silicon defoaming agent composition. The obtained defoaming agent has the advantages of instant defoaming, excellent sustained defoaming, strong shear resistance, storage stability and no floating oil in a high-temperature circulating cleaning liquid system, a high-speed sand mill slurry system and the like.

Description

Technical Field

[0001] This invention relates to the field of defoamer preparation technology, specifically to a high-content organosilicon defoamer composition for high-temperature and high-shear systems. Background Technology

[0002] Organosilicon defoamers are widely used in chemical, textile, papermaking, water treatment, and coating industries due to their low surface tension, good chemical inertness, and high defoaming efficiency. In actual production processes, many operating conditions not only require defoamers to have rapid defoaming capabilities but also to maintain long-term stable defoaming performance in complex systems with high temperatures, continuous high shear, and the coexistence of surfactants and salts. For example, systems such as high-temperature circulating cleaning fluids, high-speed sand milling slurries, and emulsion polymerization reactor solutions typically need to operate for extended periods within a temperature range of 120℃-160℃, accompanied by strong mechanical stirring or shearing, and often contain anionic or nonionic surfactants and electrolytes. These harsh conditions place far higher demands on the heat resistance, shear attenuation resistance, and sustained defoaming performance of defoamers than on static systems at room temperature.

[0003] In the existing technology, silicone defoamers are mainly divided into two categories. The first category is based on polydimethylsiloxane, combined with hydrophobic silica and other particles, which can quickly enter the foam film and cause it to rupture due to extremely low surface tension. These first-type defoamers exhibit excellent initial defoaming rates at room temperature or low shear conditions. However, under high temperature and continuous shear conditions, polydimethylsiloxane droplets are prone to re-coagulation, and active silicone oil is easily eluted or carried away from the gas-liquid interface by surfactants, leading to rapid loss of effective components and a sharp decline in defoaming ability in the later stages. The second type improves dispersibility and compatibility by randomly polyetherifying, randomly amination, or simply increasing the content of polar groups on the polysiloxane backbone. These modified defoamers show improved short-term dispersibility in high-temperature and high-shear systems. However, due to the random distribution and excessively high content of polar groups, the overall molecular compatibility is too strong, making it difficult to form an effective puncture driving force at the bubble film interface. They may even be solubilized by surfactants at high temperatures and completely lose their defoaming activity. In other words, these two types of defoamers are caught in a dilemma of mutual constraint in high-temperature, high-shear systems containing salt and surfactants: either they break foam quickly at first but fail later, or they have good dispersibility but cannot puncture the bubble film at all.

[0004] In recent years, researchers have attempted to introduce various functional groups, such as phenyl, epoxy, polyether, and amino groups, into the polysiloxane backbone, trying to balance compatibility and defoaming ability through multiple modifications. However, existing methods often employ a one-time addition of all modifiers or a random grafting strategy, resulting in uncontrollable distribution of functional groups on the molecular chain and an inability to simultaneously achieve spatial separation of the hydrophobic defoaming core and the hydrophilic anchoring interface on the same molecule. Furthermore, regarding the anti-degradation performance under high temperature and high shear conditions, existing technologies generally lack a systematic design for the internal structural stability and post-shear recovery ability of continuous organosilicon phases.

[0005] Therefore, developing an organosilicon defoamer that can simultaneously achieve rapid defoaming, continuous foam suppression, and resistance to shear decay in systems with high temperature, high shear, surfactant enrichment, and salt presence remains a pressing technical challenge in this field. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a high-content organosilicon defoamer composition for high-temperature and high-shear systems, so as to solve the problem that existing defoamers cannot achieve good high-temperature resistance, continuous foam suppression and anti-shear decay without significantly sacrificing the instantaneous foam breaking speed.

[0007] To achieve the above objectives, this invention provides a method for preparing a high-content organosilicon defoamer composition for high-temperature and high-shear resistant systems, the specific steps of which are as follows:

[0008] Preparation of low-hydrogen methylphenyl polysiloxane intermediate S1: Under nitrogen protection, octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, hydrogen-containing polymethylsiloxane and hexamethyldisiloxane are added to a reaction vessel and mixed evenly. The reaction is carried out under the action of an acidic catalyst. After the reaction is completed, the temperature is lowered and an alkaline substance is added for neutralization. After filtration to remove salt, low-boiling substances are removed under reduced pressure to obtain low-hydrogen methylphenyl polysiloxane intermediate.

[0009] S2 Preparation of polyether-epoxy modified polysiloxane intermediate: Under nitrogen protection, low-hydrogen methylphenyl polysiloxane intermediate and organic solvent are added to a reaction vessel, acetyl-terminated allyl ethylene oxide / propylene oxide co-ether and catalyst are added for addition reaction, then allyl glycidyl ether and catalyst are added to continue the reaction. After the reaction is completed, the solvent and unreacted small molecules are removed under reduced pressure to obtain polyether-epoxy modified polysiloxane intermediate;

[0010] S3 Preparation of Urea-Modified / Esterified Polysiloxanes: Under nitrogen protection, polyether-epoxy modified polysiloxane intermediates and organic solvents are added to a reaction vessel, and N,N-diethyl-1,3-propanediamine is added dropwise to carry out the first ring-opening reaction. Then, phenyl isocyanate, diisopropylamine and maleic anhydride are added sequentially to carry out a multi-step reaction. After the reaction is completed, unreacted small molecules are removed under reduced pressure to obtain urea-modified / esterified polysiloxanes.

[0011] S4 Preparation of a high-content organosilicon defoamer composition: Urea-modified / esterified polysiloxane is mixed with trimethylsiloxy-terminated methylphenyl silicone oil and trimethylsiloxy-terminated dimethyl silicone oil to form a continuous organosilicon phase. Then, hydrophobic fumed silica and precipitated silica are added for dispersion. Subsequently, defoaming treatment is performed to obtain a high-content organosilicon defoamer composition.

[0012] Preferably, the weight ratio of octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, hydrogen-containing polymethylsiloxane and hexamethyldisiloxane in step S1 is 216.0-223.0:33.0-40.0:11.0-13.0:9.5-10.5.

[0013] Preferably, the hydrogen-containing polymethylsiloxane in step S1 is a trimethylsiloxy-terminated linear hydrogen-containing polymethylsiloxane with a kinematic viscosity of 15-30 mmHg at 25°C. 2 / s, with a silicon and hydrogen content of 15.0-17.0 mmol / g and a moisture content of no more than 0.05 wt%.

[0014] Preferably, the acidic catalyst in step S1 is concentrated sulfuric acid.

[0015] Preferably, the reaction temperature in step S1 is 41-46°C, and after maintaining this temperature for 2.6-3.4 hours, the temperature is raised to 74-76°C.

[0016] Preferably, the neutralizing agent in step S1 is anhydrous sodium carbonate, and the neutralization time is 2.0-2.5 h.

[0017] Preferably, the decompression removal in step S1 is carried out at 140-142℃ and -0.094 to -0.096 MPa.

[0018] Preferably, the weight ratio of the low-hydrogen methylphenyl polysiloxane intermediate, acetyl-terminated allyl ethylene oxide / propylene oxide copolyether, and allyl glycidyl ether in step S2 is 198.0-204.0:36.0-44.0:6.8-8.2.

[0019] Preferably, the acetyl-terminated allyl ethylene oxide / propylene oxide copolyether described in step S2 has a number average molecular weight of 550-650, an ethylene oxide / propylene oxide mass ratio of 70 / 30, and a hydroxyl value not higher than 5 mg KOH / g.

[0020] Preferably, the organic solvent in step S2 is xylene.

[0021] Preferably, the addition reaction temperature in step S2 is 80-83°C and the reaction time is 1.8-2.4 h.

[0022] Preferably, the catalyst in step S2 is a chloroplatinic acid isopropanol solution with a platinum content of 1.0 wt%.

[0023] Preferably, the reaction temperature in step S2 is 78-79°C and the reaction time is 1.2-1.8h.

[0024] Preferably, the decompression removal in step S2 is carried out at 119-121℃ and -0.09 to -0.091MPa.

[0025] Preferably, the weight ratio of the polyether-epoxy modified polysiloxane intermediate, N,N-diethyl-1,3-propanediamine, phenyl isocyanate, diisopropylamine, and maleic anhydride in step S3 is 238.0-244.0:3.6-4.4:3.3-3.9:2.3-2.7:1.2-1.6.

[0026] Preferably, the organic solvent in step S3 is xylene.

[0027] Preferably, the time for adding N,N-diethyl-1,3-propanediamine in step S3 is 25-35 min.

[0028] Preferably, before adding phenyl isocyanate in step S3, the system temperature needs to be cooled to 40-45°C and the reaction should be maintained for 1.2-1.8 hours.

[0029] Preferably, before adding diisopropylamine in step S3, the system temperature needs to be raised to 72-76°C and the reaction should be maintained for 1.2-1.8 hours.

[0030] Preferably, before adding maleic anhydride in step S3, the system temperature needs to be raised to 75-78°C and the reaction should be maintained for 1.2-1.8 hours.

[0031] Preferably, the decompression removal in step S3 is carried out at 95-97℃ and -0.09 to -0.091 MPa.

[0032] Preferably, in step S3, the first stage of the ring-opening reaction is at a temperature of 58-61°C and the reaction time is 2.2-2.8 h.

[0033] Preferably, the weight ratio of the ureoyl / esterified modified polysiloxane, trimethylsiloxy-terminated methylphenyl silicone oil, trimethylsiloxy-terminated dimethyl silicone oil, hydrophobic fumed silica, and precipitated silica in step S4 is 73.0-77.0:9.0-11.5:7.0-9.0:4.8-6.2:1.2-1.8.

[0034] Preferably, the trimethylsiloxy-terminated methylphenyl silicone oil described in step S4 has a kinematic viscosity of 80-150 mmHg at 25°C. 2 / s, with a phenyl content of 5-10wt%.

[0035] Preferably, the trimethylsiloxy-terminated dimethyl silicone oil described in step S4 has a kinematic viscosity of 50-100 mmHg at 25°C. 2 / s.

[0036] Preferably, the degassing treatment in step S4 is carried out at -0.08 to -0.09 MPa for 25-35 min.

[0037] Preferably, the specific surface area of ​​the hydrophobic fumed silica in step S4 is 150-250 m². 2 / g, with a carbon content of 0.8-2.0wt%.

[0038] Preferably, the average particle size of the precipitated silica in step S4 is 3-10 μm, and the moisture content is not higher than 1.0 wt%.

[0039] Furthermore, the present invention also provides a high-content silicone defoamer composition for high-temperature and high-shear resistant systems, wherein the high-content silicone defoamer composition comprises, by weight: 73.0-77.0 parts of ureo-modified / esterified polysiloxane, 9.0-11.5 parts of trimethylsiloxy-terminated methylphenyl silicone oil, 7.0-9.0 parts of trimethylsiloxy-terminated dimethyl silicone oil, 4.8-6.2 parts of hydrophobic fumed silica, and 1.2-1.8 parts of precipitated silica.

[0040] The beneficial effects of this invention are:

[0041] This invention first constructs a methylphenyl polysiloxane framework by copolymerizing tetramethyltetraphenylcyclotetrasiloxane with octamethylcyclotetrasiloxane and hydrogen-containing polymethylsiloxane, effectively suppressing the tendency of droplet re-co-polymerization at high temperatures and the removal of active silicone oil by surfactants. Based on this, a stepwise hydrosilylation strategy is adopted, first introducing acetyl-terminated allyl ethylene oxide / propylene oxide co-ether, then introducing allyl glycidyl ether, avoiding compatibility issues caused by random grafting. Subsequently, through the continuous reaction of N,N-diethyl-1,3-propanediamine, phenyl isocyanate, diisopropylamine, and maleic anhydride, localized polar microregions are formed. This design allows the defoamer to quickly recover viscosity and interfacial activity after experiencing high temperature and high shear, significantly improving the high shear viscosity recovery rate and effectively extending its service life.

[0042] This invention retains the inherent low surface tension and rapid spreading ability of polysiloxanes, while enhancing the anchoring effect with the surfactant foam interface through moderately polar urea groups, tertiary amines, and semi-esterified groups. In high-temperature circulating cleaning liquids, high-speed sand mill slurries, and emulsion polymerization kettle liquids, this defoamer can compress the foam layer to a low level in a very short time. At the same time, under continuous shear and high temperature conditions, the effective components are not easily desorbed from the interface, so that the average foam height is always maintained in a low range within 30 minutes. Therefore, it can maintain excellent initial defoaming and continuous foam suppression performance in different media.

[0043] This invention combines hydrophobic fumed silica and precipitated silica in a continuous organosilicon phase. The synergistic effect of these two types of silica enables the defoamer to effectively suppress foam accumulation in high-speed sand milling slurry. After sand milling, the supernatant height of the slurry is extremely low and there is no floating oil, and the sieve residue is significantly reduced. At the same time, during the long-term operation of the emulsion polymerization reactor liquid, this defoamer can control the foam height at a low level after 120 minutes, ensuring the stability of the polymerization process and product quality. In addition, the composition of this invention exhibits good anti-oil separation and stratification ability under both room temperature standing and accelerated storage conditions, with moderate kinematic viscosity, which is convenient for engineering dosing and metering, and is suitable for various high-temperature and high-shear industrial defoaming scenarios. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0045] Source or nature of raw materials:

[0046] The tetramethyltetraphenylcyclotetrasiloxane has a purity of not less than 95%; the acetyl-terminated allyl ethylene oxide / propylene oxide coether has a number average molecular weight of 550-650, an ethylene oxide / propylene oxide mass ratio of 70 / 30, and a hydroxyl value not exceeding 5 mgKOH / g; the hydrogen-containing polymethylsiloxane is a trimethylsiloxy-terminated linear hydrogen-containing polymethylsiloxane with a kinematic viscosity of 15-30 mmHg at 25°C. 2 / s, silane content of 15.0-17.0 mmol / g, moisture content not exceeding 0.05 wt%; platinum content in isopropanol chloroplatinate solution of 1.0 wt%; specific surface area of ​​hydrophobic fumed silica of 150-250 m² / g. 2 / g, carbon content is 0.8-2.0wt%; the average particle size of precipitated silica is 3-10μm, and the moisture content is not higher than 1.0wt%; the kinematic viscosity of trimethylsiloxy-terminated methylphenyl silicone oil at 25℃ is 80-150mm. 2 / s, phenyl content is 5-10wt%; trimethylsiloxy-terminated dimethyl silicone oil has a kinematic viscosity of 50-100 mm at 25°C. 2 / s; The raw materials, isocyanates, maleic anhydride and solvents used should preferably be dehydrated to a moisture content of no more than 0.05wt% before use.

[0047] Example 1: A method for preparing a high-content organosilicon defoamer composition for high-temperature and high-shear resistant systems, the specific steps of which are as follows:

[0048] S1 Preparation of low-hydrogen methylphenyl polysiloxane intermediates:

[0049] In a four-necked reaction flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen protection, 220.0 g of octamethylcyclotetrasiloxane, 36.0 g of tetramethyltetraphenylcyclotetrasiloxane, 12.0 g of hydrogen-containing polymethylsiloxane, and 10.0 g of hexamethyldisiloxane were added. The mixture was stirred until homogeneous under nitrogen protection at a stirring speed of 300 r / min. The temperature was raised to 42 °C, and then 1.2 g of concentrated sulfuric acid was added dropwise. The reaction was allowed to equilibrate at 44 °C for 3 h, and then the temperature was raised to 75 °C and held for 1 h. After the reaction was completed, the temperature was lowered to 35 °C, and 3.5 g of anhydrous sodium carbonate was added for neutralization for 2 h. After filtration to remove salt, the low-boiling-point substances were removed under reduced pressure at 140 °C and -0.095 MPa for 1.5 h to obtain a low-hydrogen methylphenyl polysiloxane intermediate.

[0050] S2 Preparation of polyether-epoxy modified polysiloxane intermediates:

[0051] In another reaction flask, 200.0 g of the above-mentioned low-hydrogen methylphenyl polysiloxane intermediate and 70.0 g of xylene were added. Under nitrogen protection, the temperature was raised to 81 °C. First, 40.0 g of acetyl-terminated allyl ethylene oxide / propylene oxide co-ether was added, followed by 0.12 g of isopropanol chloroplatinate solution. The reaction was maintained at 81 °C for 2 h. Then, the temperature was lowered to 78 °C, and 7.5 g of allyl glycidyl ether and the balance 0.08 g of isopropanol chloroplatinate solution were added to the system. The reaction was continued for 1.5 h. After the reaction was completed, xylene and unreacted small molecules were removed under reduced pressure at 120 °C and -0.09 MPa to obtain the polyether-epoxy modified polysiloxane intermediate.

[0052] S3 Preparation of Urea-modified / Esterified Polysiloxanes:

[0053] 240.0 g of polyether-epoxy modified polysiloxane intermediate and 50.0 g of xylene were added to a reaction flask. Under nitrogen protection, the temperature was raised to 59 °C. First, 4.0 g of N,N-diethyl-1,3-propanediamine was added dropwise over a period of 30 min. The reaction was continued for 2.5 h to carry out the first ring-opening reaction. After the first ring-opening reaction was completed, the temperature was lowered to 43 °C, and 3.65 g of phenyl isocyanate was added dropwise. The reaction was continued for 1.5 h. Then, the temperature was raised to 74 °C, and 2.5 g of diisopropylamine was added. The reaction was continued for 1.5 h to carry out the second ring-opening reaction. After the second ring-opening reaction was completed, the temperature was raised to 77 °C, and 1.4 g of maleic anhydride was added. The reaction was continued for 2 h. After the reaction was completed, unreacted small molecules were removed under reduced pressure at 95 °C and -0.09 MPa to obtain ureolated / esterified modified polysiloxane.

[0054] S4 Preparation of High-Content Organosilicon Defoamer Composition:

[0055] Take 75.0g of ureo-modified / esterified polysiloxane, 10.0g of trimethylsiloxy-terminated methylphenyl silicone oil, and 8.0g of trimethylsiloxy-terminated dimethyl silicone oil, and mix them evenly to form a continuous organosilicon phase. Then, add 5.5g of hydrophobic fumed silica and 1.5g of precipitated silica to the aforementioned continuous organosilicon phase in two portions, disperse them at 43℃ for 60min, and then degas them at -0.085MPa for 30min to obtain a high-content organosilicon defoamer composition for high-temperature and high-shear systems.

[0056] Example 2: A method for preparing a high-content organosilicon defoamer composition for high-temperature and high-shear resistant systems, the specific steps of which are as follows:

[0057] Preparation of low-hydrogen methylphenyl polysiloxane intermediate S1: In a four-necked reaction flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen protection, 216.0 g of octamethylcyclotetrasiloxane, 33.0 g of tetramethyltetraphenylcyclotetrasiloxane, 11.0 g of hydrogen-containing polymethylsiloxane, and 9.5 g of hexamethyldisiloxane were added. The mixture was stirred evenly under nitrogen protection at a stirring speed of 280 r / min. The temperature was raised to 41 °C, and then 1.0 g of concentrated sulfuric acid was added dropwise. The reaction was allowed to equilibrate at 41 °C for 2.6 h, and then the temperature was raised to 74 °C and held for 1.0 h. After the reaction was completed, the temperature was lowered to 35 °C, and 3.0 g of anhydrous sodium carbonate was added for neutralization for 2.0 h. After filtration to remove salt, the low-boiling substances were removed under reduced pressure at 140 °C and -0.094 MPa for 1.3 h to obtain the low-hydrogen methylphenyl polysiloxane intermediate.

[0058] Preparation of polyether-epoxy modified polysiloxane intermediate S2: 198.0 g of the above-mentioned low-hydrogen methylphenyl polysiloxane intermediate and 68.0 g of xylene were added to another reaction flask. The temperature was raised to 80 °C under nitrogen protection. First, 36.0 g of acetyl-terminated allyl ethylene oxide / propylene oxide co-ether was added, followed by 0.10 g of isopropanol chloroplatinate solution. The reaction was maintained at 80 °C for 1.8 h. Then, the temperature was lowered to 78 °C, and 6.8 g of allyl glycidyl ether and the remaining 0.06 g of isopropanol chloroplatinate solution were added to the system. The reaction was continued for 1.2 h. After the reaction was completed, xylene and unreacted small molecules were removed under reduced pressure at 119 °C and -0.09 MPa to obtain the polyether-epoxy modified polysiloxane intermediate.

[0059] Preparation of ureoyl / esterified modified polysiloxanes by S3: 238.0 g of polyether-epoxy modified polysiloxane intermediate and 48.0 g of xylene were added to a reaction flask. Under nitrogen protection, the temperature was raised to 58 °C. First, 3.6 g of N,N-diethyl-1,3-propanediamine was added dropwise, with the addition time controlled at 25 min. The reaction was continued for 2.2 h to carry out the first ring-opening reaction. After the first ring-opening reaction was completed, the system was cooled to 40 °C, and 3.3 g of phenyl isocyanate was added dropwise. The reaction was continued for 1.2 h. Then, the system was heated to 72 °C, and 2.3 g of diisopropylamine was added. The reaction was continued for 1.2 h to carry out the second ring-opening reaction. After the second ring-opening reaction was completed, the system was heated to 75 °C, and 1.2 g of maleic anhydride was added. The reaction was continued for 1.6 h. After the reaction was completed, unreacted small molecules were removed under reduced pressure at 95 °C and -0.09 MPa to obtain ureoyl / esterified modified polysiloxanes.

[0060] S4 Preparation of a high-content organosilicon defoamer composition: Take 73.0g of ureo-modified / esterified polysiloxane, 9.0g of trimethylsiloxy-terminated methylphenyl silicone oil, and 7.0g of trimethylsiloxy-terminated dimethyl silicone oil, mix them evenly to form a continuous organosilicon phase; then add 4.8g of hydrophobic fumed silica and 1.2g of precipitated silica to the aforementioned continuous organosilicon phase in two portions, disperse at 41℃ for 50min, and then defoam at -0.08MPa for 25min to obtain a high-content organosilicon defoamer composition for high-temperature and high-shear systems.

[0061] Example 3: A method for preparing a high-content organosilicon defoamer composition for high-temperature and high-shear resistant systems, the specific steps of which are as follows:

[0062] Preparation of low-hydrogen methylphenyl polysiloxane intermediate S1: In a four-necked reaction flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen protection, 223.0 g of octamethylcyclotetrasiloxane, 40.0 g of tetramethyltetraphenylcyclotetrasiloxane, 13.0 g of hydrogen-containing polymethylsiloxane, and 10.5 g of hexamethyldisiloxane were added. The mixture was stirred evenly under nitrogen protection at a stirring speed of 320 r / min. The temperature was raised to 44 °C, and then 1.4 g of concentrated sulfuric acid was added dropwise. The reaction was allowed to equilibrate at 46 °C for 3.4 h, and then the temperature was raised to 76 °C and held for 1.2 h. After the reaction was completed, the temperature was lowered to 35 °C, and 4.0 g of anhydrous sodium carbonate was added for neutralization for 2.5 h. After filtration to remove salt, the low-boiling substances were removed under reduced pressure at 142 °C and -0.096 MPa for 1.8 h to obtain the low-hydrogen methylphenyl polysiloxane intermediate.

[0063] Preparation of polyether-epoxy modified polysiloxane intermediate S2: 204.0 g of the above-mentioned low-hydrogen methylphenyl polysiloxane intermediate and 74.0 g of xylene were added to another reaction flask. The temperature was raised to 83 °C under nitrogen protection. First, 44.0 g of acetyl-terminated allyl ethylene oxide / propylene oxide co-ether was added, followed by 0.14 g of isopropanol chloroplatinate solution. The reaction was maintained at 83 °C for 2.4 h, and then lowered to 79 °C. 8.2 g of allyl glycidyl ether and the remaining 0.10 g of isopropanol chloroplatinate solution were added to the system, and the reaction was continued for 1.8 h. After the reaction was completed, xylene and unreacted small molecules were removed under reduced pressure at 121 °C and -0.091 MPa to obtain the polyether-epoxy modified polysiloxane intermediate.

[0064] Preparation of ureoyl / esterified modified polysiloxanes by S3: 244.0 g of polyether-epoxy modified polysiloxane intermediate and 54.0 g of xylene were added to a reaction flask. Under nitrogen protection, the temperature was raised to 61 °C. First, 4.4 g of N,N-diethyl-1,3-propanediamine was added dropwise, with the addition time controlled at 35 min. The reaction was continued for 2.8 h to carry out the first ring-opening reaction. After the first ring-opening reaction was completed, the system was cooled to 45 °C, and 3.9 g of phenyl isocyanate was added dropwise. The reaction was continued for 1.8 h. Then, the system was heated to 76 °C, and 2.7 g of diisopropylamine was added. The reaction was continued for 1.8 h to carry out the second ring-opening reaction. After the second ring-opening reaction was completed, the system was heated to 78 °C, and 1.6 g of maleic anhydride was added. The reaction was continued for 2.4 h. After the reaction was completed, unreacted small molecules were removed under reduced pressure at 97 °C and -0.091 MPa to obtain ureoyl / esterified modified polysiloxanes.

[0065] S4 Preparation of a high-content organosilicon defoamer composition: Take 77.0g of ureo-modified / esterified polysiloxane, 11.5g of trimethylsiloxy-terminated methylphenyl silicone oil, and 9.0g of trimethylsiloxy-terminated dimethyl silicone oil, mix them evenly to form a continuous organosilicon phase; then add 6.2g of hydrophobic fumed silica and 1.8g of precipitated silica to the aforementioned continuous organosilicon phase in two portions, disperse at 47℃ for 70min, and then defoam at -0.09MPa for 35min to obtain a high-content organosilicon defoamer composition for high-temperature and high-shear systems.

[0066] Comparative Example 1: The difference from Example 1 is that tetramethyltetraphenylcyclotetrasiloxane is not added in S1, and the amount of octamethylcyclotetrasiloxane added is adjusted from 220.0g to 256.0g to keep the total amount of cyclic compound added unchanged; the other conditions are the same as in Example 1.

[0067] Comparative Example 2: The difference from Example 1 is that in S2, 40.0 g of acetyl-terminated allyl ethylene oxide / propylene oxide co-ether and 7.5 g of allyl glycidyl ether were added together at once to the mixture of low-hydrogen methyl phenyl polysiloxane intermediate and xylene, and 0.20 g of isopropanol chloroplatinate solution was added at once. The reaction was then carried out continuously at 81°C for 3.5 h. The other conditions were the same as in Example 1.

[0068] Comparative Example 3: The difference from Example 1 is that in S3, 4.0 g of N,N-diethyl-1,3-propanediamine and 2.5 g of diisopropylamine were added together at 59°C to a mixture of polyether-epoxy modified polysiloxane intermediate and xylene, with the total dropping time controlled at 30 min, followed by continuous reaction at 59°C for 4.0 h; the other conditions were the same as in Example 1.

[0069] Comparative Example 4: The difference from Example 1 is that 3.65g of phenyl isocyanate was not added in S3, and an equal mass of 3.65g of xylene was added to maintain the total mass of the reaction system in this step being basically the same; the other conditions are the same as in Example 1.

[0070] Comparative Example 5: The difference from Example 1 is that maleic anhydride is not added in S3, and an equal mass of xylene is added to maintain the total mass of the reaction system in this step being basically the same; the other conditions are the same as in Example 1.

[0071] Comparative Example 6: The difference from Example 1 is that hydrophobic fumed silica is not added in S4, and it is replaced with an equal amount of precipitated silica to keep the total amount of silica added unchanged; the other conditions are the same as in Example 1.

[0072] Performance testing

[0073] The high-content silicone defoamer compositions obtained in the examples and comparative examples were used as test samples. After each test sample was prepared, it was left to stand at 25°C for 24 hours. After confirming that there was no visible layering, the test was carried out.

[0074] The high-temperature, high-shear salt-containing surfactant simulation solution was prepared as follows: 955.0g of deionized water, 20.0g of sodium dodecylbenzenesulfonate, 10.0g of fatty alcohol polyoxyethylene ether AEO-9, 5.0g of triethanolamine, and 10.0g of sodium chloride were taken and stirred at room temperature until completely dissolved to obtain a high-temperature, high-shear salt-containing surfactant simulation solution with a total mass of 1000.0g.

[0075] The high-speed sand mill slurry simulation solution was prepared as follows: 630.0g of deionized water, 350.0g of light calcium carbonate, 6.0g of sodium polyacrylate dispersant, 4.0g of sodium dodecyl sulfate and 10.0g of sodium chloride were taken, stirred evenly at room temperature, and the pH was adjusted to 8.5±0.1 to obtain a high-speed sand mill slurry simulation solution with a total mass of 1000.0g.

[0076] The emulsion polymerization reactor slurry simulation solution was prepared as follows: 974.0g of deionized water, 15.0g of sodium dodecyl sulfate, 8.0g of polyvinyl alcohol and 3.0g of sodium bicarbonate were taken and stirred until completely dissolved to obtain an emulsion polymerization reactor slurry simulation solution with a total mass of 1000.0g.

[0077] The amount of each sample added was 0.10 wt% of the total mass of the treated system, and the following tests were performed:

[0078] Particle size distribution: According to GB / T 19077-2024, 0.10 g of each sample was added to 50.0 mL of isoalkane dispersion medium, and the sample was dispersed by low-energy ultrasonication for 30 s and then tested immediately. The instrument circulation speed was set to 1500 r / min, the sample refractive index was set to 1.40, and the dispersion medium refractive index was set to 1.39. D10, D50 and D90 were recorded.

[0079] Isothermal thermal stability: The test was conducted in accordance with GB / T 29174-2012. 10 mg of each sample from the examples and comparative examples was weighed and placed in the sample crucible of the thermogravimetric analyzer. The temperature was increased to 150 °C at 20 °C / min under a nitrogen atmosphere with a nitrogen flow rate of 50 mL / min. After reaching 150 °C, the temperature was maintained for 120 min. The mass retention rate at 30 min, 60 min, and 120 min was recorded, and the mass retention rate at 120 min was taken as the result.

[0080] Kinematic viscosity: The kinematic viscosity was measured in accordance with GB / T 265-1988. Each sample of the example and comparative examples was placed in a constant temperature bath at 25.0℃ for 30 min and then measured using a capillary viscometer with a flow time greater than 200 s. Two sets of measurements were performed for each sample, and each set was measured four times. The arithmetic mean was taken as the kinematic viscosity result at 25℃.

[0081] Rotational rheological properties: Performed according to JY / T 0590-2020, using a parallel plate fixture with a parallel plate diameter of 25 mm and a test gap of 1.0 mm; after loading each sample, equilibrate at 25℃ for 5 min, then perform rotational rheological testing for 0.1-1000 s. -1 Shear rate scan, recorded for 100 seconds -1 The apparent viscosity was then measured; subsequently, the temperature was increased to 140°C and equilibrated for 5 minutes, and the viscosity was measured at 1000 s. -1 The apparent viscosity was recorded at 600s after continuous shearing; then cooled to 25℃ and allowed to stand for 5 minutes, and the viscosity was recorded at 100s. -1 The apparent viscosity was measured again, and the viscosity recovery rate after high shear was calculated.

[0082] Instantaneous defoaming performance: Referring to the foaming, sample addition, and result judgment principles of GB / T 21885-2008, and combined with the high temperature and high shear conditions of this application, an enhanced test was conducted. A 1.0L stainless steel high-pressure reactor with a sight glass was used, and a rotor-stator shear head was installed inside the reactor. 500.0g of high temperature and high shear salt-containing surfactant simulation solution was added to the reactor, the temperature was raised to 140℃ and equilibrated for 10min, and foam was formed by shearing at 6000r / min for 2min. Then, 0.50g of the sample to be tested was injected into the reactor through the high-pressure injection valve within 3s. The stopwatch was started and the foam height was read through the sight glass scale. The time required for the foam layer to drop to 10mm was recorded as one defoaming time. Each sample was tested in parallel 3 times, and the average value was taken as the result.

[0083] Continuous defoaming performance: After the first defoaming is completed according to the above test, the temperature inside the reactor is maintained at 140℃, and shearing is continued at 3000r / min for 30min; the foam height is read through the sight glass scale at 5min, 10min, 15min, 20min, 25min and 30min respectively, and the average foam height over 30min is calculated.

[0084] Shear attenuation resistance: Take 5.00g of each sample to be tested and place it in a 50mL stainless steel cup. Pre-shear at 10000r / min for 20min using a high-speed disperser at 140℃. After cooling to 25℃, measure the defoaming time once again according to the above experiment, and measure the average foam height for 30min as described above. Calculate the change rate of defoaming time before and after pre-shearing and the change rate of average foam height for 30min respectively.

[0085] High-speed sand mill slurry compatibility test: 1000.0g of high-speed sand mill slurry simulation liquid was added to a 1.0L vertical laboratory sand mill, and 0.8mm diameter zirconia beads were loaded with a volume fraction of 70%. The jacket temperature was controlled at 60℃, and the spindle speed was controlled at 10m / s. After adding 1.00g of the sample to be tested, sand milling was carried out continuously for 30min. The bubble layer thickness was read through the observation window every 10min, and the maximum bubble layer thickness was recorded. Immediately after sand milling, 100.0g of slurry was filtered through a 100-mesh sieve, and the mass of the residue was weighed. Then, 100.0g of slurry was left to stand at 25℃ for 2h, and the height of the supernatant layer and the presence of floating oil were recorded.

[0086] Long-term foam suppression performance of emulsion polymerization reactor liquid: 1000.0g of simulated emulsion polymerization reactor liquid was placed in a 1.0L four-necked glass reactor. A mechanical stirrer, reflux condenser, and graduated observation tube were installed. After stirring at 600r / min for 30min at 85℃ to form stable foam, 1.00g of the test sample was added, and stirring was continued for 120min. The foam height was read at 20min, 40min, 60min, 80min, 100min, and 120min, and the foam height at 120min was recorded as the result value. The test results are shown in Table 1.

[0087] Table 1 Performance Test Results

[0088]

[0089] Data Analysis: As can be seen from the data in Table 1, the high-content organosilicon defoamer composition for high-temperature, high-shear systems prepared in this invention maintains a good balance in terms of particle size distribution, isothermal thermal stability, high shear viscosity recovery rate, and sustained foam suppression. This indicates that the system does not rely on a single component to achieve short-term effects. Instead, it is based on a methylphenyl polysiloxane backbone, through the stepwise introduction of acetyl-terminated allyl ethylene oxide / propylene oxide coether and allyl glycidyl ether, followed by the continuous reaction of N,N-diethyl-1,3-propanediamine, phenyl isocyanate, diisopropylamine, and maleic anhydride, forming a continuous organosilicon phase that balances limited compatibility, interfacial retention, and high post-shear recovery. Therefore, it is inferred that this composition is beneficial for simultaneously maintaining primary defoaming and subsequent foam suppression in high-temperature circulating cleaning solutions, high-speed milling slurries, and emulsion polymerization reactor solutions.

[0090] As can be seen from the data in Table 1 for Example 1 and Comparative Example 1, without the addition of tetramethyltetraphenylcyclotetrasiloxane, the system exhibits significantly worse performance in isothermal thermal stability, sustained foam suppression, and shear decay resistance. The main reason for this is that the reduction in methylphenylsiloxane units in the methylphenylpolysiloxane backbone results in insufficient interfacial retention and chain segment stability at high temperatures, leading to a greater likelihood of loss of the continuous organosilicon phase in high-temperature salt-containing surfactant systems.

[0091] As can be seen from the data in Example 1 and Comparative Example 2 in Table 1, when acetyl-terminated allyl ethylene oxide / propylene oxide co-polyether and allyl glycidyl ether are added together in one step, the particle size distribution becomes wider, and the sustained foam suppression and shear decay resistance decrease. The main reason is that when the two types of components containing double bonds are added simultaneously, the distribution of epoxy sites and polyether segments is not concentrated enough, making it difficult to first form restricted compatibility and then complete the subsequent local polarization. As a result, it is difficult to maintain a balance between dispersibility and the ability to puncture the foam film.

[0092] As can be seen from the data in Table 1 for Example 1 and Comparative Example 3, although the system still has a certain defoaming ability after N,N-diethyl-1,3-propanediamine and diisopropylamine are added together at once, the performance deteriorates faster after high shear, and the sustained defoaming effect is insufficient. The main reason is that when different amine components open the ring together at the same stage, it is difficult to form the anchoring micro-regions where urea groups and tertiary amines coexist, as well as the subsequent sterically hindered tertiary amine alcohol structure. This makes it difficult for local polarization to be concentrated in the same side chain region, resulting in a decrease in interfacial retention and recovery ability after high shear.

[0093] As can be seen from the data in Table 1 for Example 1 and Comparative Example 4, without the addition of phenyl isocyanate, the primary defoaming, sustained foam suppression, and high shear viscosity recovery rate of the system all decreased. The main reason for this is that after phenyl isocyanate participates in the reaction, it helps to form a more stable urea group structure near the local epoxy sites, thereby enhancing the role of the continuous organosilicon phase at the bubble-film interface. Therefore, phenyl isocyanate does not act in isolation, but rather, together with the preceding ring-opening and subsequent esterification, amplifies the primary defoaming and sustained foam suppression effects.

[0094] As can be seen from the data in Table 1 for Example 1 and Comparative Example 5, without the addition of maleic anhydride, the initial defoaming of the system remained at a good level, but the sustained foam suppression, shear attenuation resistance, and long-term foam control ability in the emulsion polymerization reactor decreased more significantly. The main reason for this is that the localized hemiesterification structure formed after the addition of maleic anhydride helps improve the residence stability of the localized polar regions at the interface, making it less likely for the effective components to migrate too quickly under continuous disturbance. This indicates that the role of maleic anhydride is not simply to increase polarity, but rather to work with ureation and pre-ring-opening to stabilize the continuous organosilicon phase, thereby amplifying the later foam suppression effect.

[0095] As can be seen from the data in Example 1 and Comparative Example 6 in Table 1, after replacing the hydrophobic fumed silica with an equal amount of precipitated silica, the particle size distribution became coarser, and the thickness of the foam layer, the height of the supernatant layer, and the risk of floating oil in the sand milling slurry significantly increased. At the same time, the performance retention after high shear also deteriorated significantly. It can be seen that the use of the two types of silica is not a simple filling, but rather a significant synergy between storage stability, dynamic defoaming, and continuous foam suppression.

[0096] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a high-content organosilicon defoamer composition for high-temperature and high-shear resistant systems, characterized in that, Includes the following steps: Preparation of low-hydrogen methylphenyl polysiloxane intermediate S1: Under nitrogen protection, octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, hydrogen-containing polymethylsiloxane and hexamethyldisiloxane are added to a reaction vessel and mixed evenly. The reaction is carried out under the action of an acidic catalyst. After the reaction is completed, the temperature is lowered and an alkaline substance is added for neutralization. After filtration to remove salt, low-boiling substances are removed under reduced pressure to obtain low-hydrogen methylphenyl polysiloxane intermediate. S2 Preparation of polyether-epoxy modified polysiloxane intermediate: Under nitrogen protection, low-hydrogen methylphenyl polysiloxane intermediate and organic solvent are added to a reaction vessel, acetyl-terminated allyl ethylene oxide / propylene oxide co-ether and catalyst are added for addition reaction, then allyl glycidyl ether and catalyst are added to continue the reaction. After the reaction is completed, the solvent and unreacted small molecules are removed under reduced pressure to obtain polyether-epoxy modified polysiloxane intermediate; S3 Preparation of Urea-modified / Esterified Polysiloxanes: Under nitrogen protection, polyether-epoxy modified polysiloxane intermediates and organic solvents were added to a reaction vessel, and N,N-diethyl-1,3-propanediamine was added dropwise to carry out the first ring-opening reaction. Then, phenyl isocyanate, diisopropylamine and maleic anhydride were added sequentially to carry out the reaction. After the reaction was completed, unreacted small molecules were removed under reduced pressure to obtain ureoyl / esterified modified polysiloxane. S4 Preparation of High-Content Organosilicon Defoamer Composition: A ureo- / esterified modified polysiloxane was mixed with trimethylsiloxy-terminated methylphenyl silicone oil and trimethylsiloxy-terminated dimethyl silicone oil to form a continuous organosilicon phase. Then, hydrophobic fumed silica and precipitated silica were added for dispersion. Subsequently, defoaming treatment was performed to obtain a high-content organosilicon defoamer composition. The weight ratio of octamethylcyclotetrasiloxane, tetramethyltetraphenylcyclotetrasiloxane, hydrogen-containing polymethylsiloxane, and hexamethyldisiloxane in step S1 is 216.0-223.0:33.0-40.0:11.0-13.0:9.5-10.5; The weight ratio of the low-hydrogen methylphenyl polysiloxane intermediate, acetyl-terminated allyl ethylene oxide / propylene oxide copolyether, and allyl glycidyl ether in step S2 is 198.0-204.0:36.0-44.0:6.8-8.

2. The weight ratio of the polyether-epoxy modified polysiloxane intermediate, N,N-diethyl-1,3-propanediamine, phenyl isocyanate, diisopropylamine, and maleic anhydride in step S3 is 238.0-244.0:3.6-4.4:3.3-3.9:2.3-2.7:1.2-1.

6. The weight ratio of the ureoylated / esterified modified polysiloxane, trimethylsiloxy-terminated methylphenyl silicone oil, trimethylsiloxy-terminated dimethyl silicone oil, hydrophobic fumed silica, and precipitated silica in step S4 is 73.0-77.0:9.0-11.5:7.0-9.0:4.8-6.2:1.2-1.

8.

2. The preparation method according to claim 1, characterized in that, The reaction temperature in step S1 is 41-46℃, and after maintaining this temperature for 2.6-3.4 hours, the temperature is raised to 74-76℃.

3. The preparation method according to claim 1, characterized in that, The acidic catalyst in step S1 is concentrated sulfuric acid; the neutralizing agent is anhydrous sodium carbonate, and the neutralization time is 2.0-2.5 h.

4. The preparation method according to claim 1, characterized in that, The hydrogen-containing polymethylsiloxane mentioned in step S1 is a linear hydrogen-containing polymethylsiloxane with trimethylsiloxy groups at the end, and its kinematic viscosity at 25°C is 15-30 mm. 2 / s, with a silicon and hydrogen content of 15.0-17.0 mmol / g and a moisture content of no more than 0.05 wt%.

5. The preparation method according to claim 1, characterized in that, The acetyl-terminated allyl ethylene oxide / propylene oxide copolyether in step S2 has a number average molecular weight of 550-650, an ethylene oxide / propylene oxide mass ratio of 70 / 30, and a hydroxyl value not higher than 5 mg KOH / g; the catalyst is a chloroplatinic acid isopropanol solution with a platinum content of 1.0 wt%.

6. The preparation method according to claim 1, characterized in that, The addition reaction in step S2 is carried out at a temperature of 80-83℃ and a reaction time of 1.8-2.4h; the decompression removal is carried out at 119-121℃ and -0.09~-0.091MPa.

7. The preparation method according to claim 1, characterized in that, In step S3, the first stage of the ring-opening reaction is carried out at a temperature of 58-61℃ for 2.2-2.8 hours.

8. The preparation method according to claim 1, characterized in that, The trimethylsiloxy-terminated methylphenyl silicone oil described in step S4 has a kinematic viscosity of 80-150 mmHg at 25°C. 2 / s, phenyl content is 5-10wt%; the kinematic viscosity of the trimethylsiloxy-terminated dimethyl silicone oil at 25°C is 50-100 mm. 2 / s.

9. The preparation method according to claim 1, characterized in that, The specific surface area of ​​the hydrophobic fumed silica mentioned in step S4 is 150-250 m². 2 / g, with a carbon content of 0.8wt%-2.0wt%; the average particle size of the precipitated silica is 3-10μm, and the moisture content is not higher than 1.0wt%.

10. A high-content organosilicon defoamer composition for high-temperature, high-shear resistant systems, characterized in that, The high-content organosilicon defoamer composition prepared according to any one of claims 1-9 comprises, by weight: 73.0-77.0 parts of ureo-modified / esterified polysiloxane, 9.0-11.5 parts of trimethylsiloxy-terminated methylphenyl silicone oil, 7.0-9.0 parts of trimethylsiloxy-terminated dimethyl silicone oil, 4.8-6.2 parts of hydrophobic fumed silica, and 1.2-1.8 parts of precipitated silica.

Images