Modified organic silicon foam agent and preparation method thereof

Abstract

The invention provides a modified organic silicon defoaming agent and a preparation method thereof, and the modified organic silicon defoaming agent is mainly prepared from the following raw materials in parts by mass: 20 to 30 parts of low-hydrogen silicone oil, 10 to 18 parts of epoxy modified carboxymethyl cellulose, 35 to 50 parts of allyl alcohol polyether, 5 to 12 parts of a cross-linking agent and 0.0001 to 0.0005 part of chloroplatinic acid. According to the modified organic silicon foaming agent, through the synergistic effect of the epoxy modified carboxymethyl cellulose, the polyether and the organic silicon, the defoaming efficiency and the water solubility are both considered, the temperature resistance and the shear resistance are improved through a cross-linked structure, and the modified organic silicon foaming agent is suitable for multiple fields such as water-based paint, water treatment and fermentation.

Description

Technical Field

[0001] This invention relates to the field of silicone foam preparation, and specifically to a modified silicone foam and its preparation method. Background Technology

[0002] Organosilicon defoamers are widely used in water-based coatings, water treatment, bio-fermentation, and printing and dyeing industries due to their low surface tension, high defoaming efficiency, and excellent weather resistance. However, traditional organosilicon defoamers suffer from poor water solubility and insufficient compatibility with aqueous systems, easily leading to stratification and oil floating phenomena, resulting in reduced defoaming effect and product defects (such as pinholes in coatings and failure of water treatment agents). To improve water solubility, existing technologies often use polyether-modified organosilicon, introducing hydrophilic polyether segments into the silicon-oxygen chain to adjust the hydrophilic-hydrophobic balance. However, these products have poor temperature and shear resistance; under extreme conditions such as high temperature and strong stirring, the polyether segments are prone to detachment, leading to a decrease in defoaming durability.

[0003] Carboxymethyl cellulose (CMC), as a natural water-soluble polymer, possesses excellent thickening, stabilizing, and film-forming properties. However, it lacks defoaming activity, and its direct addition increases system viscosity, affecting the spreading efficiency of the defoamer. Epoxy-modified CMC, due to the introduction of epoxy groups, can undergo cross-linking reactions with compounds containing amino and hydroxyl groups. However, in existing technologies, the composites of epoxy-modified CMC and organosilicon are mostly physical blends, resulting in weak intermolecular forces and easy separation in complex systems, making it difficult to balance defoaming efficiency and stability. Furthermore, improper selection and dosage control of cross-linking agents can easily lead to over-cross-linking, causing product embrittlement and deterioration of dispersibility.

[0004] Furthermore, in existing allyl alcohol polyether preparation processes, the lack of precise control over the EO / PO polymerization ratio and feeding method leads to uneven polyether segment structure, affecting the reactivity matching with organosilicon. Therefore, achieving a tight bond between epoxy-modified CMC, polyether, and organosilicon through chemical crosslinking to construct a synergistic system of "hydrophobic defoaming - hydrophilic stability," and developing a modified organosilicon defoamer that balances high defoaming efficiency, good water solubility, and temperature and shear resistance, has become a key requirement for addressing the pain points of existing technologies.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The primary objective of this invention is to provide a modified silicone foaming agent that, through the synergistic effect of epoxy-modified carboxymethyl cellulose, polyether, and silicone, balances defoaming efficiency and water solubility. The cross-linked structure enhances temperature and shear resistance, making it suitable for various fields such as water-based coatings, water treatment, and fermentation.

[0007] The second objective of this invention is to provide a method for preparing the above-mentioned high-efficiency oil-soluble dewaxing agent. This method is simple to operate, operates under mild conditions, is pollution-free, produces no waste, and is safe and environmentally friendly.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: This invention provides a modified organosilicon defoamer, which is mainly made from the following raw materials: by mass parts, 20-30 parts of low-hydrogen silicone oil, 10-18 parts of epoxy-modified carboxymethyl cellulose, 35-50 parts of allyl alcohol polyether, 5-12 parts of crosslinking agent, and 0.0001-0.0005 parts of chloroplatinic acid.

[0009] Preferably, as a further feasible option, by weight parts, there are 22-28 parts of low-hydrogen silicone oil, 12-17 parts of epoxy-modified carboxymethyl cellulose, 36-45 parts of allyl alcohol polyether, 7-10 parts of crosslinking agent, and 0.0002-0.0004 parts of chloroplatinic acid.

[0010] Preferably, as a further feasible option, the following components are included by weight: 26 parts of low-hydrogen silicone oil, 14 parts of epoxy-modified carboxymethyl cellulose, 40 parts of allyl alcohol polyether, 8 parts of crosslinking agent, and 0.0003 parts of chloroplatinic acid.

[0011] Preferably, as a further feasible option, the crosslinking agent is one or more selected from ethylenediamine, hexamethylenediamine, six-membered cyclodiamine, diethylenetriamine, hydroxyethyl ethylenediamine, and isophorone diamine.

[0012] In the modified silicone defoamer of this invention, epoxy-modified CMC, allyl alcohol-modified polyether, and low-hydrogen silicone oil are crosslinked and combined through an appropriate crosslinking agent to form strong intermolecular forces, constructing a synergistic system of "hydrophobic defoaming-hydrophilic stability". This system can balance defoaming performance and stability in complex industrial wastewater systems. CMC has good thickening, stabilizing, and film-forming properties. After the introduction of epoxy groups, the introduced epoxy groups (-CH(O)-CH2) can undergo ring-opening reactions with the amino groups of crosslinking agents (such as diethylenetriamine and isophorone diamine) to form stable covalent bonds. This allows epoxy-CMC to form a three-dimensional network structure with hydrogen-containing silicone oil and allyl alcohol polyether through "chemical bridging". At the same time, after epoxy modification, its molecular chain retains a large number of hydrophilic groups such as carboxyl and hydroxyl groups, which can significantly improve the dispersibility and stability of the defoamer in aqueous systems (such as water-based coatings and detergents), avoiding the oil floating and agglomeration problems caused by excessive hydrophobicity of traditional silicone defoamers. Allyl alcohol polyethers, by introducing carbon-carbon double bonds (-CH=CH2) at their molecular ends, can undergo hydrosilylation with the Si-H bonds of hydrogen-containing silicone oil under chloroplatinic acid catalysis, forming stable Si-C covalent bonds and chemically grafting the polyether segments onto the organosilicon molecules. The rigid framework of epoxy-CMC complements the flexible segments of allyl alcohol polyethers: the rigid framework can be anchored in the aqueous system, providing a stable dispersion carrier for the organosilicon defoaming components; the flexible polyether segments ensure the rapid spreading of the defoamer on the bubble surface. In addition, the carboxyl and hydroxyl groups in its molecules can form hydrogen bonds with polar groups in the system (such as resins in coatings and electrolytes in water treatment), improving the adaptability of the defoamer in complex systems and avoiding performance degradation caused by environmental interference (such as pH fluctuations and high salinity).

[0013] More preferably, the crosslinking agent is diethylenetriamine, which contains three active amino groups (two primary amino groups and one secondary amino group), providing more crosslinking sites. The primary amino group has high reactivity and can rapidly undergo a ring-opening reaction with the epoxy groups of epoxy-modified carboxymethyl cellulose (epoxy-CMC); the secondary amino group has mild reactivity and can slowly participate in crosslinking in the later stages, forming a gradient reaction process. This "multi-site + gradient activity" characteristic results in a higher crosslinking density (each molecule can connect to three epoxy groups) and a more uniform crosslinking structure, avoiding localized over-crosslinking (such as embrittlement and bubble encapsulation) caused by excessively rapid reaction of small molecule crosslinking agents, thus enhancing the overall mechanical properties and shear resistance of the defoamer. The amino groups of diethylenetriamine can also form hydrogen bonds with the hydroxyl groups (-OH) in allyl alcohol polyether and undergo weak condensation with the silanol groups (Si-OH) generated by the hydrolysis of hydrogen-containing silicone oil, further strengthening the interfacial bonding between the components (epoxy-CMC, allyl alcohol polyether, and hydrogen-containing silicone oil). This "chemical crosslinking + hydrogen bond synergy" mechanism solves the problems of poor component compatibility and easy stratification in traditional physical blending systems. Simultaneously, as a small-molecule amine, the introduced amino group retains some polarity after crosslinking, forming polar interactions with the carboxyl and hydroxyl groups of epoxy-CMC and the ether bonds of allyl alcohol polyether, improving the dispersibility of the defoamer in aqueous systems. Its short-chain structure (containing two ethylene groups) does not excessively increase the hydrophilicity of the system, avoiding weakening the hydrophobic defoaming activity of the hydrogen-containing silicone oil. This "moderate polarity" characteristic allows the defoamer to be suitable for both highly aqueous systems (such as detergents and water treatment) and moderately polar systems (such as water-based coatings), effectively breaking bubbles and broadening its application range.

[0014] Preferably, as a further feasible option, the epoxy-modified carboxymethyl cellulose is mainly prepared from the following raw materials: by mass percentage, 10-15% carboxymethyl cellulose, 2-5% sodium hydroxide, 3-7% epoxy reagent, and the remainder is solvent.

[0015] Preferably, as a further feasible option, the allyl alcohol polyether is mainly prepared from the following raw materials: by mass percentage, allyl alcohol 8-10%, EO 50-60%, PO 25-35%, and sodium hydroxide 0.3-0.5%.

[0016] The present invention also provides a method for preparing a modified silicone defoamer, comprising: mixing low-hydrogen silicone oil with allyl alcohol polyether, adding chloroplatinic acid, heating for pre-reaction, adding epoxy-modified carboxymethyl cellulose and crosslinking agent, replacing with nitrogen and sealing for protection, controlling the temperature for reaction, and obtaining the modified silicone defoamer after the reaction is completed.

[0017] Preferably, as a further feasible option, the pre-reaction temperature is 50~60℃ and the pre-reaction time is 25-35min.

[0018] Preferably, as a further feasible option, the temperature-controlled reaction temperature is 85-95℃ and the reaction time is 12-18h.

[0019] In fact, the preparation method of the modified organosilicon defoamer provided by the present invention mainly includes the following three steps: Step 1: Preparation of epoxy carboxymethyl cellulose; The epoxy-modified carboxymethyl cellulose is mainly prepared from carboxymethyl cellulose, sodium hydroxide, epoxy reagent, and solvent, and the steps are as follows: Add solvent to carboxymethyl cellulose and stir to swell. After swelling, add sodium hydroxide to the system to activate the hydroxyl groups. The temperature is controlled at 40-60℃ throughout the process, the swelling time is 30-60 min, and the activation time is 30-60 min. Epoxy reagent was slowly added dropwise to the above system at a controlled temperature of 40-60℃ for 40-60 minutes. After the addition was completed, the temperature was raised to 60-70℃ and the reaction was continued. After the reaction was completed, the pH of the system was adjusted to 6-7 with hydrochloric acid to terminate the reaction. After filtration and washing with isopropanol, the mixture was vacuum dried at 60-80℃ to obtain epoxy-modified carboxymethyl cellulose. Preferably, as a further feasible option, the epoxy reagent is glycidyl ester; Preferably, as a further feasible option, the solvent is a 70% aqueous ethanol solution; The heat preservation reaction temperature is 65℃; The heat preservation reaction time is 3 hours; In this invention, the epoxy group of glycidyl ester is directly linked to the ester group. The electron-withdrawing effect of the ester group enhances the electron-deficient properties of the epoxy ring, enabling it to specifically undergo a nucleophilic ring-opening reaction with the hydroxyl group (-OH) on the CMC molecular chain. Compared with epichlorohydrin, the side reaction rate with the carboxyl group (-COONa) is reduced by 15%~20%. High selectivity ensures efficient grafting of the epoxy group, stabilizing the epoxy value of the modified epoxy-CMC at 0.2~0.4 mol / 100g, providing sufficient active sites for subsequent reactions with crosslinking agents such as diethylenetriamine, and avoiding fluctuations in crosslinking efficiency. Simultaneously, the reaction introduces the ester group (-COO-), whose polarity allows for weak interactions with the ether bond of allyl alcohol polyether and the silicon-oxygen bond of hydrogen-containing silicone oil, improving component compatibility. Furthermore, the flexible structure of the ester group alleviates the rigid stress after crosslinking, preventing product embrittlement and enhancing the shear resistance of the defoamer.

[0020] Step 2: Preparation of allyl alcohol polyether; The allyl alcohol polyether is mainly prepared from allyl alcohol, EO, PO, and sodium hydroxide, and the steps are as follows: Sodium hydroxide and initiator propylene alcohol were added to the high-pressure reactor, and the reactor lid was quickly tightened. EO and PO were mixed in a storage tank at P = -0.1 MPa. 5-10% (total EO / PO mass) of EO / PO was then added through the storage tank. Stirring and heating were started to initiate the reaction. The remaining EO / PO was added in batches, 5-10% (total EO / PO mass) each time, maintaining the temperature during addition. After the addition was complete, the reaction continued until finished, then the temperature was lowered to 105°C. The reaction was allowed to mature until the pressure inside the reactor returned to -0.1 MPa. The product was then cooled and discharged to obtain allyl alcohol polyether.

[0021] Preferably, as a further feasible option, the feeding maintains the reaction temperature at 115°C; Preferably, as a further feasible option, the reaction time for the reaction to complete is 3 hours; Step 3: Prepare the modified organosilicon defoamer; Low-hydrogen silicone oil is mixed with allyl alcohol polyether, chloroplatinic acid is added, and the mixture is heated to 50-60℃ for a pre-reaction of 25-35 minutes. Then, epoxy-modified carboxymethyl cellulose and crosslinking agent are added, and the mixture is sealed with nitrogen purging and protected. The reaction is carried out at 85-95℃ for 12-18 hours. After the reaction is completed, the modified organosilicon defoamer is obtained.

[0022] Preferably, as a further feasible option, the pre-reaction temperature is 55°C and the pre-reaction time is 30 min; Preferably, as a further feasible option, the temperature-controlled reaction temperature is 90°C and the reaction time is 15 hours; In this invention, the reaction employs a stepwise strategy of "first chemical grafting (hydrosilylation), then cross-linking and curing (epoxy-amine reaction)" to chemically bond three core components, constructing a structurally stable and hydrophilic-hydrophobic balanced modified organosilicon defoamer. This overcomes the shortcomings of traditional products, such as poor compatibility and insufficient stability, and is a key process for achieving high-efficiency defoaming performance. Specifically, the low-hydrogen silicone oil (containing Si-H bonds) provides hydrophobic active sites and is the core functional unit for defoaming; the allyl alcohol polyether (containing terminal C=C double bonds) acts as a "bridge," introducing hydrophilic polyether segments into the organosilicon molecule through the reaction of the double bonds with the Si-H bonds; and chloroplatinic acid (catalyst) catalyzes the Markovnikov addition reaction between the Si-H bonds and the C=C double bonds, forming stable Si-C covalent bonds. The essence of this reaction is the cleavage of the Si-H bonds in low-hydrogen silicone oil under platinum catalysis. Hydrogen atoms add to the methylene carbon (-CH2-) of the double bond, while silicon atoms combine with the methylene carbon (=CH-) of the double bond to generate an "organosilicon-polyether" block structure. A 30-minute pre-reaction ensures that over 80% of the double bonds and Si-H bonds complete the reaction, providing a stable amphiphilic intermediate for subsequent crosslinking and avoiding competition between the double bonds and epoxy groups in the main reaction. The ring-opening reaction of the epoxy group and the amino group: The amino groups (-NH2, -NH-) of diethylenetriamine act as nucleophiles, attacking the electron-deficient carbon of the epoxy ring, generating hydroxyl groups (-OH) and CN bonds, causing the cellulose molecular chains to crosslink into a network. The ether bonds (-O-) of the polyether form hydrogen bonds with the hydroxyl groups (-OH) and ester groups (-COO-) of cellulose, further enhancing the interfacial bonding of the components.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention constructs a three-dimensional covalent cross-linked network to solve the problems of layering and oil drift in traditional organosilicon defoamers. Through hydrosilylation of allyl alcohol polyether and hydrogen-containing silicone oil, and epoxy ring-opening cross-linking of epoxy modified carboxymethyl cellulose (epoxy-CMC) and cross-linking agent, chemical bonding of each component is achieved, which significantly improves the dispersion stability in aqueous phase and the structural durability under high temperature and strong shear conditions.

[0024] (2) Precisely balance defoaming efficiency and water solubility. By adjusting the ratio of allyl alcohol polyether EO / PO segments, and synergistically combining the hydrophilic framework of epoxy-CMC with the hydrophobic activity of organosilicon, the contradiction between "water solubility and defoaming" is resolved. The defoaming rate is ≥92% in 5 minutes, and the foam suppression durability is improved by more than 40%, making it suitable for multi-phase systems. (3) Functional synergy broadens application scenarios. The thickening and stabilizing effect of epoxy-CMC, the flexible adjustment of allyl alcohol polyether, and the core defoaming effect of organosilicon work together to make the product have excellent temperature resistance (efficiency retention ≥85% at 120℃) and shear resistance. It has strong compatibility with complex systems and can be adapted to extreme working conditions such as high viscosity coatings and high salt water treatment solutions.

[0025] (4) The process is environmentally friendly and easy to industrialize. Low-toxicity glycidyl ester and high-efficiency diethylenetriamine are selected to produce products without toxic volatiles and with no harmful residues. The process parameters are mild, the raw material ratios are highly adaptable, and the intermediate preparation and final polymerization are smoothly connected, making it suitable for large-scale production and in line with the trend of green chemical industry. Detailed Implementation

[0026] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0027] Example 1 The modified organosilicon defoamer and its preparation method in this invention specifically involve the following three steps: Step 1: Prepare epoxy-modified carboxymethyl cellulose.

[0028] The raw materials and amounts of the epoxy-modified carboxymethyl cellulose are as follows: Carboxymethyl cellulose: 140g; Sodium hydroxide: 36g; Glycidyl esters: 40g; 70% ethanol aqueous solution: 784g; The preparation steps of the epoxy-modified carboxymethyl cellulose are as follows: 1. Swelling and activation: Add 140g of carboxymethyl cellulose and 784g of 70% ethanol aqueous solution to the reaction flask, stir at 40℃ for 45min to swell; add 36g of solid sodium hydroxide, and continue stirring at 40℃ for 45min to activate, to obtain a homogeneous viscous system.

[0029] 2. Epoxy grafting: Heat the system to 50°C, slowly add 40g of glycidyl ester (dropping time 45min) while controlling the temperature, and after the addition is complete, raise the temperature to 65°C and keep the reaction at this temperature for 3h.

[0030] 3. Post-treatment: Adjust the pH of the system to 6.5 with 10% hydrochloric acid, filter and collect the solid; wash 3 times with isopropanol (2 times the mass of solid), and vacuum dry at 60℃ for 4h to obtain epoxy CMC-01 (epoxy value 0.32mol / 100g).

[0031] Step 2: Prepare allyl alcohol polyether.

[0032] The raw materials and dosages of the allyl alcohol-modified polyether are as follows: Allyl alcohol: 90g; EO (ethylene oxide): 580g; PO (propylene oxide): 320g; Sodium hydroxide: 4g; The preparation steps of the allyl alcohol modified polyether are as follows: 1. Feeding and pretreatment: Add 4g of sodium hydroxide and 90g of allyl alcohol to a 500mL high-pressure reactor, seal it, and then evacuate to -0.1MPa.

[0033] 2. Polymerization reaction: Mix 580g EO and 320g PO, and first pressurize 100g (10% of the total monomer amount) of the mixed monomer into the storage tank, start stirring (300r / min), and heat to 115℃ for reaction; after the pressure stabilizes (about 0.3MPa), add the remaining 800g of mixed monomer in batches (10g each time, 30min interval), and maintain the reaction at 115℃.

[0034] 3. Curing and Discharging: After feeding, cool down to 105℃ and cure for 2 hours until the pressure inside the reactor returns to -0.1MPa. Cool to room temperature and discharge to obtain allyl alcohol polyether-01 (hydroxyl value 56mgKOH / g, double bond content 0.28mol / 100g).

[0035] Step 3: Prepare modified organosilicon defoamer.

[0036] The raw materials and dosages of the modified organosilicon defoamer in this invention are as follows: Low-hydrogen silicone oil (0.12% hydrogen content): 270g; Epoxy CMC-01: 170g; Allyl alcohol polyether-01: 450g; Diethylenetriamine: 100g; Chloroplatinic acid catalyst: 2 ppm (based on platinum element, relative to the total mass of low-hydrogen silicone oil and allyl alcohol polyether, i.e., 0.00144 g). The preparation steps of the modified organosilicon defoamer are as follows: 1. Pre-reaction: Add 270g of low-hydrogen silicone oil and 450g of allyl alcohol polyether to the reaction flask, stir and mix, then add chloroplatinic acid, and pre-react at 55℃ for 30min (initiated by hydrosilylation). 2. Crosslinking reaction: Add 170g of epoxy-modified carboxymethyl cellulose and 100g of diethylenetriamine, purge with nitrogen to replace air, seal, and heat to 90℃ for 15h. 3. Finished product: After the reaction is complete, the product is naturally cooled to room temperature, resulting in a light yellow viscous liquid, which is the modified organosilicon defoamer. Example 2 The specific implementation steps are the same as in Example 1, except that the 70% ethanol aqueous solution in step one of Example 1 is changed to a 50% ethanol aqueous solution.

[0037] Example 3 The specific implementation steps are the same as in Example 1, except that the 70% ethanol aqueous solution in step one of Example 1 is replaced with an 80% ethanol aqueous solution.

[0038] Example 4 The specific implementation steps are the same as in Example 1, except that the amount of 70% ethanol aqueous solution in step one of Example 1 is adjusted to 220g (accounting for 50.46%).

[0039] Example 5 The specific implementation steps are the same as in Example 1, except that the amount of 70% ethanol aqueous solution used in step one of Example 1 is adjusted to 1000g (accounting for 82.24%).

[0040] Example 6 The specific implementation steps are the same as in Example 1, except that the amount of sodium hydroxide in step one of Example 1 is adjusted to 10g (accounting for 1.03%).

[0041] Example 7 The specific implementation steps are the same as in Example 1, except that the amount of sodium hydroxide used in step one of Example 1 is adjusted to 75g (accounting for 7.22%).

[0042] Example 8 The specific implementation steps are the same as in Example 1, except that the amount of glycidyl ester used in step one of Example 1 is adjusted to 20g (accounting for 2.04%).

[0043] Example 9 The specific implementation steps are the same as in Example 1, except that the amount of glycidyl ester used in step one of Example 1 is adjusted to 90g (8.57%).

[0044] Example 10 The specific implementation steps are the same as in Example 1, except that the heat preservation reaction in step one of Example 1 is adjusted to 55°C.

[0045] Example 11 The specific implementation steps are the same as in Example 1, except that the heat preservation reaction in step one of Example 1 is adjusted to 80°C.

[0046] Example 12 The specific implementation steps are the same as in Example 1, except that the heat preservation reaction time in step one of Example 1 is adjusted to 1.5h.

[0047] Example 13 The specific implementation steps are the same as in Example 1, except that the heat preservation reaction time in step one of Example 1 is adjusted to 5 hours.

[0048] Example 14 The specific implementation steps are the same as in Example 1, except that the amount of allyl alcohol used in step two of Example 1 is adjusted to 60g (accounting for 6.22%).

[0049] Example 15 The specific implementation steps are the same as in Example 1, except that the amount of allyl alcohol used in step two of Example 1 is adjusted to 120g (accounting for 11.72%).

[0050] Example 16 The specific implementation steps are the same as in Example 1, except that the amount of sodium hydroxide used in step two of Example 1 is adjusted to 2g (accounting for 0.2%).

[0051] Example 17 The specific implementation steps are the same as in Example 1, except that the amount of sodium hydroxide used in step two of Example 1 is adjusted to 6g (accounting for 0.6%).

[0052] Example 18 The specific implementation steps are the same as in Example 1, except that the EO / PO ratio in step two of Example 1 is adjusted to EO 50% and PO 35%.

[0053] Example 19 The specific implementation steps are the same as in Example 1, except that the EO / PO ratio in step two of Example 1 is adjusted to EO 60% and PO 30%.

[0054] Example 20 The specific implementation steps are the same as in Example 1, except that the temperature of EO / PO added in step two of Example 1 is adjusted to 105°C.

[0055] Example 21 The specific implementation steps are the same as in Example 1, except that the temperature of EO / PO added in step two of Example 1 is adjusted to 125°C.

[0056] Example 22 The specific implementation steps are the same as in Example 1, except that the reaction time for complete reaction in step two of Example 1 is adjusted to 2 hours.

[0057] Example 23 The specific implementation steps are the same as in Example 1, except that the reaction time for complete reaction in step two of Example 1 is adjusted to 4 hours.

[0058] Example 24 The specific implementation steps are the same as in Example 1, except that the reaction temperature of the pre-reaction in step three of Example 1 is adjusted to 45°C and the reaction time is adjusted to 40 min.

[0059] Example 25 The specific implementation steps are the same as in Example 1, except that the reaction temperature of the pre-reaction in step three of Example 1 is adjusted to 65°C and the reaction time is adjusted to 20 min.

[0060] Example 26 The specific implementation steps are the same as in Example 1, except that the reaction temperature of the crosslinking reaction in step three of Example 1 is adjusted to 80°C and the reaction time is 20h.

[0061] Example 27 The specific implementation steps are the same as in Example 1, except that the reaction temperature of the crosslinking reaction in step three of Example 1 is adjusted to 100°C and the reaction time is adjusted to 10h.

[0062] Experimental Example 1: Performance Testing of Epoxy-Modified Carboxymethyl Cellulose The epoxy-modified carboxymethyl cellulose prepared in Examples 1-13 was tested for its CMC swelling ratio and epoxy value. The final results are shown in Table 1 below: Table 1 Experimental Results

[0063] As can be seen from the above values, Examples 1-13 demonstrate the optimal ratio and performance of epoxy-modified carboxymethyl cellulose prepared in this invention under the optimal parameters. Example 1 exhibits the best CMC swelling ratio and epoxy value, significantly outperforming other examples. This is because Example 1's advantage lies in its optimized component ratio, and key parameters such as ethanol concentration, ethanol-water solution volume, sodium hydroxide volume, and reaction temperature and time are all within their optimal ranges. Simultaneously, the epoxy groups of glycidyl ester are directly linked to the ester groups. The electron-withdrawing effect of the ester groups enhances the electron-deficient characteristics of the epoxy ring, enabling it to specifically undergo a nucleophilic ring-opening reaction with the hydroxyl groups (-OH) on the CMC molecular chain, reducing the side reaction rate with the carboxyl groups (-COONa). High selectivity ensures efficient grafting of epoxy groups, stabilizing the epoxy value of the modified epoxy-CMC at 0.2~0.4 mol / 100g, providing sufficient active sites for subsequent reactions with crosslinking agents such as diethylenetriamine, and avoiding fluctuations in crosslinking efficiency. Furthermore, the reaction introduces ester groups (-COO-), which provide a key guarantee for the crosslinking efficiency and performance stability of the subsequent defoamer. Its polarity can form a weak interaction with the ether bond of allyl alcohol polyether and the silicon-oxygen bond of hydrogen-containing silicone oil, thereby improving the compatibility of the components. The flexible structure of the ester group can alleviate the rigid stress after crosslinking, prevent the product from becoming brittle, and enhance the shear resistance of the defoamer.

[0064] Experimental Example 2: Performance Testing of Allyl Alcohol Polyether The allyl alcohol polyethers prepared in Examples 14-23 were tested for their hydroxyl value, double bond content, and PDI (molecular weight distribution index). The final results are shown in Table 1 below: Table 1 Experimental Results

[0065] As shown by the above values, Examples 14-23 demonstrate the influence of process variables in the preparation of allyl alcohol polyethers in this invention on hydroxyl value, double bond content, and PDI. Example 1 exhibits the best performance in hydroxyl value, double bond content, and PDI, with data significantly superior to other examples. This is because Example 1's advantage lies in its optimized polymerization process parameters, with key factors such as allyl alcohol dosage, sodium hydroxide dosage, EO / PO ratio, polymerization temperature, and time all within optimal ranges. Furthermore, the terminal double bonds provided by allyl alcohol as an initiator can specifically undergo hydrosilylation reactions with the Si-H bonds of low-hydrogen silicone oil under chloroplatinic acid catalysis, exhibiting low side reaction rates with other functional groups. High selectivity ensures efficient chemical bonding between the polyether and organosilicon, stabilizing the double bond content of the allyl alcohol polyether at 0.25~0.30 mol / 100g, providing sufficient active sites for subsequent hydrosilylation reactions and avoiding the risk of defoamer stratification due to physical blending. Furthermore, the EO / PO structure of the polyether segments provides a key guarantee for the hydrophilic-hydrophobic balance and performance stability of the subsequent defoamer. Its ether bonds can form hydrogen bonds with the hydroxyl and ester groups of epoxy-CMC, improving component compatibility; the flexible segments of polyether can alleviate the rigid stress after crosslinking of epoxy-CMC.

[0066] Experimental Example 3: Performance Testing of Modified Organosilicon Defoamer The modified organosilicon defoamers prepared in Examples 24-27 were tested for stability, compatibility, defoaming efficiency, and foam suppression performance. The final results are shown in Table 2 below: Table 2 Experimental Results

[0067] As can be seen from the above values, Examples 24-27 demonstrate the influence of process variables in the preparation of the modified silicone defoamer in this invention on the stability, compatibility, defoaming efficiency, and foam suppression performance of the defoamer. A comparison with the performance of the modified silicone defoamer obtained in Example 1 reveals that only when the temperature and time of both the pre-reaction and cross-linking reactions are within the optimal range can the comprehensive performance of the defoamer—"highly efficient defoaming, long-lasting foam suppression, stable storage, and full system compatibility"—be achieved. In Example 24, the pre-reaction was carried out at a low temperature for a long time, resulting in insufficient hydrosilylation efficiency. The remaining double bonds would compete with the epoxy groups of the epoxy-modified carboxymethyl cellulose in the subsequent cross-linking reaction (double bond-epoxy addition), leading to a disordered cross-linking network structure. The remaining Si-H bonds were prone to self-polymerization during the high-temperature cross-linking stage (85-95°C), generating siloxane oligomers. In Example 25, the pre-reaction was carried out at a high temperature for a short time, exacerbating the self-polymerization of the double bonds in the allyl alcohol polyether by the side reaction. Simultaneously, the high temperature caused uneven reaction and excessive ineffective grafting, leading to a complete imbalance in the hydrophilicity-hydrophobicity balance of the system. Examples 26-27 involved low-temperature long-time and high-temperature short-time cross-linking reactions, respectively resulting in incomplete epoxy-amino ring-opening, a loose and uneven cross-linking network, and exacerbated side reactions and excessive cross-linking. In summary, both the pre-reaction and cross-linking reactions require strict control of reaction temperature and time. Furthermore, high-temperature reactions, due to irreversible side reactions and more extreme network destruction, have a more severe negative impact on the performance of the defoamer.

Claims

1. A modified organosilicon defoamer, characterized in that, It is mainly made from the following raw materials: by mass, 20-30 parts of low-hydrogen silicone oil, 10-18 parts of epoxy-modified carboxymethyl cellulose, 35-50 parts of allyl alcohol polyether, 5-12 parts of crosslinking agent, and 0.0001-0.0005 parts of chloroplatinic acid.

2. The modified organosilicon defoamer according to claim 1, characterized in that, By weight, the composition includes 22-28 parts of low-hydrogen silicone oil, 12-17 parts of epoxy-modified carboxymethyl cellulose, 36-45 parts of allyl alcohol polyether, 7-10 parts of crosslinking agent, and 0.0002-0.0004 parts of chloroplatinic acid.

3. The modified organosilicon defoamer according to claim 1, characterized in that, By weight, the composition includes 26 parts low-hydrogen silicone oil, 14 parts epoxy-modified carboxymethyl cellulose, 40 parts allyl alcohol polyether, 8 parts crosslinking agent, and 0.0003 parts chloroplatinic acid.

4. The modified organosilicon defoamer according to any one of claims 1-3, characterized in that, The crosslinking agent is one or more of ethylenediamine, hexamethylenediamine, six-membered cyclodiamine, diethylenetriamine, hydroxyethyl ethylenediamine, and isophorone diamine.

5. The modified organosilicon defoamer according to any one of claims 1-3, characterized in that, The epoxy-modified carboxymethyl cellulose is mainly produced from the following raw materials: by mass percentage, 10-15% carboxymethyl cellulose, 2-5% sodium hydroxide, 3-7% epoxy reagent, and the remainder is solvent.

6. The modified organosilicon defoamer according to any one of claims 1-3, characterized in that, The allyl alcohol polyether is mainly prepared from the following raw materials: by mass percentage, allyl alcohol 8-10%, EO 50-60%, PO 25-35%, and sodium hydroxide 0.3-0.5%.

7. The method for preparing the modified organosilicon defoamer according to any one of claims 1-6, characterized in that, Low-hydrogen silicone oil was mixed with allyl alcohol polyether, chloroplatinic acid was added, and the mixture was heated for a pre-reaction. Epoxy-modified carboxymethyl cellulose and a crosslinking agent were added, nitrogen was used for purging and sealing for protection, and the temperature was controlled for the reaction. After the reaction was completed, a modified organosilicon defoamer was obtained.

8. The preparation method according to claim 7, characterized in that, The pre-reaction temperature is 50~60℃ and the pre-reaction time is 25-35min.

9. The preparation method according to claim 7, characterized in that, The temperature-controlled reaction temperature is 85-95℃, and the reaction time is 12-18h.

Images