Low viscosity high defoaming efficiency carbon five defoaming agent and preparation process thereof

Abstract

The application discloses a low-viscosity high-foam-breaking-efficiency C5 antifoaming agent and a preparation process thereof. The raw materials of the antifoaming agent include branched C5 resin, hydroxyl silicone oil, polyoxyethylene polyoxypropylene ether and the like; the branched C5 resin is prepared by polymerization of C5 fraction and triallyl isocyanurate and grafting of maleic anhydride, and the silane-modified nano-silicon dioxide is prepared by modification of nano-silicon dioxide by gamma-aminopropyl triethoxysilane. The preparation process adopts linkage control of DCS and SIS systems, first synthesizes an antifoaming agent intermediate, uses benzene as a base material in a compounding process, then automatically adds the antifoaming agent intermediate, the silane-modified nano-silicon dioxide and the like under the control of DCS, and after stirring, ultrasonic dispersion and filtration, appearance, kinematic viscosity and other indexes are detected, and after passing the detection, the antifoaming agent is dynamically weighed and packaged through an automatic filling system. The antifoaming agent has low viscosity, high foam-breaking efficiency and long-term stability, is suitable for multiple industrial scenes, and has safe and reliable process and high automation degree.

Description

Technical Field

[0001] This invention relates to the field of defoamer technology, and in particular to a low-viscosity, high-defoaming-efficiency C5 defoamer and its preparation process. Background Technology

[0002] C5 fraction is an important byproduct of ethylene cracking units, primarily composed of various active olefin components such as isoprene, cyclopentadiene, isoprene, and n-pentene. This resource is widely available and relatively inexpensive, making its use in the synthesis of functional polymers and further preparation of defoamers an effective way to achieve high-value utilization of petroleum byproducts. Traditional processes typically employ free radical solution polymerization to polymerize the olefin components in the C5 fraction into a linear C5 resin, which serves as the carrier or continuous phase for the defoamer. However, due to the relatively regular molecular chain structure of linear polymers, intermolecular entanglement and stacking easily occur, resulting in a high bulk viscosity in the final defoamer product. This characteristic leads to increased transport resistance and pumping energy consumption in practical applications, and hinders its rapid dispersion and spreading when added to foaming systems, making it difficult to quickly establish effective defoaming points on the foam film surface.

[0003] Furthermore, traditional C5 defoamers mostly employ physical-mechanical blending, simply mixing defoaming actives such as silicone oil and polyether surfactants with C5 resin. Due to the lack of strong chemical bonds or specific interactions between the components, the apparent homogeneity of the system is mainly maintained by van der Waals forces, resulting in less than ideal intrinsic thermodynamic compatibility. During long-term static storage or temperature fluctuations, the system is prone to phase separation, manifesting as silicone oil precipitation, resin coagulation, or additive sedimentation, leading to uneven distribution or even deactivation of the defoaming active components. This not only causes a significant decrease in defoaming efficiency but also makes it difficult to guarantee the product's foam suppression durability, resulting in instability in industrial processes requiring continuous foam suppression and limiting its application in high-end operating conditions.

[0004] To overcome the aforementioned shortcomings, various improvements have been attempted in existing technologies. For example, by adding solid particles such as nano-silica and hydrophobic silica, their surface effects can be utilized to accelerate the drainage and rupture of the foam film, thereby improving the instantaneous defoaming ability; or by compounding surfactants with different HLB values ​​to adjust the hydrophilic-lipophilic balance of the system and improve its dispersibility in specific media. However, these improvements often only focus on solving a single performance indicator and may even introduce new problems. For example, untreated nanoparticles are prone to agglomeration in organic media, which not only reduces their effective specific surface area and defoaming efficiency but also causes precipitation problems during storage, affecting the product's appearance and stability; while introducing too much water-soluble component such as polyether may help with initial dispersion, it may weaken the compatibility of the defoamer in the oil phase system, exacerbate the tendency of stratification, and further increase the system viscosity.

[0005] Therefore, existing technologies have not yet systematically resolved the key technical contradiction of achieving a balance between low viscosity, high defoaming efficiency, long-lasting foam suppression performance, and excellent storage stability in C5 defoamers, starting from the essential level of molecular structure design and multi-component synergistic effects. Developing a novel C5 defoamer that can comprehensively improve these properties is of great significance for broadening its application scope and increasing product added value. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and to propose a low-viscosity, high-defoaming-efficiency C5 defoamer and its preparation process.

[0007] To achieve the above objectives, the present invention provides a low-viscosity, high-efficiency C5 defoamer, comprising the following raw materials in parts by weight: branched C5 resin: 10-20 parts, hydroxyl silicone oil: 5-10 parts, polyoxyethylene polyoxypropylene ether: 2-4 parts, silane-modified nano silica: 1-3 parts, toluene: 100 parts, and polyglycerol fatty acid ester: 0.5-1 parts.

[0008] The branched C5 resin is prepared by free radical polymerization of C5 fraction and triallyl isocyanurate branched monomer, followed by grafting with maleic anhydride.

[0009] The silane-modified nano-silica is prepared by modifying nano-silica with γ-aminopropyltriethoxysilane.

[0010] Preferably, the method for preparing the branched C5 resin includes the following steps:

[0011] (1) Add triallyl isocyanurate to toluene to prepare a branched monomer solution. Dry maleic anhydride to a water content of <20ppm and add it to toluene to prepare a maleic anhydride-toluene solution. The polymerization reactor is purged with nitrogen three times to ensure that the oxygen content in the reactor is <50ppm.

[0012] (2) Add the C5 fraction, dicumyl peroxide and toluene to the polymerization reactor, heat to 105-115℃ with stirring, add the branched monomer solution dropwise over 40-60 min, and keep the reaction temperature for 2-3 h after the addition is complete; keep the reaction temperature at 105-115℃, add maleic anhydride-toluene solution dropwise over 1-2 h, and keep the reaction temperature for 1-3 h after the addition is complete.

[0013] (3) Cool the system to 70-80℃, and distill under reduced pressure to remove unreacted monomers and oligomers to obtain branched C5 resin.

[0014] More preferably, the method for preparing the branched C5 resin includes the following steps:

[0015] (1) Add triallyl isocyanurate to toluene to prepare a branched monomer solution. Dry maleic anhydride to a water content of <20ppm and add it to toluene to prepare a maleic anhydride-toluene solution. The polymerization reactor is purged with nitrogen three times to ensure that the oxygen content in the reactor is <50ppm.

[0016] (2) Add the C5 fraction, dicumyl peroxide and toluene to the polymerization reactor, heat to 110°C with stirring, add the branched monomer solution dropwise over 45 min, and keep the reaction temperature for 3 h after the addition is complete; keep the reaction temperature at 110°C, add maleic anhydride-toluene solution dropwise over 1.5 h, and keep the reaction temperature for 2 h after the addition is complete.

[0017] (3) Cool the system to 75°C and distill under reduced pressure to remove unreacted monomers and oligomers to obtain branched C5 resin.

[0018] Preferably, the mass concentration of the branched monomer solution in (1) is 10%, and the mass concentration of the maleic anhydride-toluene solution is 5%.

[0019] Preferably, the C5 fraction in (2) is composed of the following by weight percentage: 35-42% isoprene, 18-25% 1,3-pentadiene, 22-28% cyclopentadiene, 5-9% n-pentene, and 5-9% 2-pentene, and is pretreated by dehydration to a water content of <30ppm.

[0020] More preferably, the C5 fraction in (2) is composed of the following by weight percentage: 40% isoprene, 22% 1,3-pentadiene, 25% cyclopentadiene, 8% n-pentene, and 5% 2-pentene, and is pretreated by dehydration to a water content of <30ppm.

[0021] Preferably, in (2), the C5 fraction, dicumyl peroxide, toluene, branched monomer solution and maleic anhydride-toluene solution are in a weight ratio of 100:0.25-0.5:50-60:8-15:140-240.

[0022] More preferably, in (2), the C5 fraction, dicumyl peroxide, toluene, branched monomer solution and maleic anhydride-toluene solution are in a weight ratio of 100:0.35:55:12:190.

[0023] Preferably, the method for preparing the silane-modified nano-silica includes the following steps:

[0024] Nano-silica was added to an ethanol / water mixture, and γ-aminopropyltriethoxysilane was added under stirring. The mixture was heated to 60-70℃ and reacted for 6-10 hours. The solid was collected by centrifugation, washed and dried to obtain silane-modified nano-silica.

[0025] More preferably, the method for preparing the silane-modified nano-silica includes the following steps:

[0026] Nano-silica was added to an ethanol / water mixture, and γ-aminopropyltriethoxysilane was added under stirring. The mixture was heated to 65°C and reacted for 8 hours. The solid was collected by centrifugation, washed and dried to obtain silane-modified nano-silica.

[0027] Preferably, in the method for preparing silane-modified nano-silica, the nano-silica, the ethanol / water mixed solution, and the γ-aminopropyltriethoxysilane are in a weight ratio of 1:10-30:0.08-0.15.

[0028] More preferably, in the method for preparing silane-modified nano-silica, the nano-silica, the ethanol / water mixed solution, and the γ-aminopropyltriethoxysilane are in a weight ratio of 1:20:0.12.

[0029] Preferably, in the method for preparing silane-modified nano-silica, the particle size of the nano-silica is 40-60 nm, and the volume ratio of ethanol to water in the ethanol / water mixed solution is 9:1.

[0030] Furthermore, this invention also provides a preparation process for a low-viscosity, high-defoaming-efficiency C5 defoamer, employing a DCS automated control program and a SIS safety automated control program in linkage, including the following steps:

[0031] S1. Under nitrogen protection and with the linkage control of DCS and SIS systems, hydroxyl silicone oil, polyoxyethylene polyoxypropylene ether, and catalyst are added to a reactor equipped with a water separator and a reflux condenser. Xylene is added as an azeotropic solvent. The mixture is heated to 120-130℃ with stirring. When the DCS monitors that the amount of water separated by the water separator is close to the theoretical value, the reaction endpoint is determined, heating is stopped, anhydrous sodium bicarbonate is added to the system, and the mixture is stirred for 30-60 minutes. The mixture is then filtered, and the system is cooled to 80-90℃. Vacuum distillation is then started to remove the solvent and unreacted low-molecular-weight polyether / hydroxyl silicone oil fragments to obtain a polyether-hydroxyl silicone oil intermediate.

[0032] S2. Under nitrogen protection and with the joint control of DCS and SIS systems, polyether-hydroxy silicone oil intermediate, branched C5 resin, catalyst and xylene are added to a reactor equipped with a water separator and reflux condenser. The mixture is heated to 140-150℃ with stirring. When the DCS monitors that the amount of water separated by the water separator is close to the theoretical value, the reaction endpoint is determined, heating is stopped, anhydrous sodium bicarbonate is added to the system, and the mixture is stirred for 30-60 minutes. After filtration, the system is cooled to 80-90℃, and vacuum distillation is started to remove the solvent and oligomers to obtain the defoamer intermediate.

[0033] S3. DCS control first adds toluene as a base material to the mixing tank, heats it to 60-80℃, then the DCS sets the feeding amounts of defoamer intermediate, silane-modified nano-silica, and polyglycerol fatty acid ester, which are automatically added to the mixing tank. The DCS starts the reducer and controls the stirring speed to 600-1000 rpm for 20-40 minutes. Then, it is ultrasonically dispersed at 300-400W power for 20-40 minutes. After naturally cooling to room temperature, it is filtered through a 200-mesh filter to obtain a low-viscosity, high-defoaming-efficiency C5 defoamer. Samples are taken to test the appearance, kinematic viscosity, density, freezing point, and active ingredient content. After passing the test, it is packaged by programmable automatic filling system, with dynamic weighing to control the net content error to ±0.5kg, and then stored in the warehouse. Non-conforming products are handled according to the non-conforming product control procedure.

[0034] Preferably, the hydroxyl content of the hydroxyl silicone oil in S1 is 9.2%, and the number average molecular weight is 2000-2500.

[0035] Preferably, the EO / PO molar ratio of the polyoxyethylene polyoxypropylene ether in S1 is 1.5:1, and the number average molecular weight is 1500-2000.

[0036] Preferably, in S1, the weight ratio of hydroxyl silicone oil, catalyst, xylene and anhydrous sodium bicarbonate is 1:0.01-0.03:8-12:0.001-0.005.

[0037] Preferably, the catalyst in S1 is p-toluenesulfonic acid.

[0038] Preferably, in S2, the branched C5 resin, catalyst, xylene, and anhydrous sodium bicarbonate are in a weight ratio of 1:0.01-0.03:8-12:0.001-0.005.

[0039] Preferably, the catalyst in S2 is p-toluenesulfonic acid.

[0040] Preferably, the mechanism of action of the low-viscosity, high-defoaming-efficiency C5 defoamer of the present invention is explained as follows:

[0041] The mechanism of action of the low-viscosity, high-defoaming-efficiency carbon 5 defoamer in this invention is based on the structural characteristics of each component and the synergistic system formed by covalent bonding. It achieves efficient foam control through a continuous action of "viscosity regulation-foam breaking-foam suppression," as detailed below:

[0042] Branched C5 resin serves as the core carrier. Its branched structure, constructed through triallyl isocyanurate, overcomes the molecular chain entanglement problem of traditional linear resins, significantly reducing intermolecular forces within the system and laying the foundation for the low viscosity characteristics of the defoamer. Simultaneously, the anhydride groups introduced by maleic anhydride grafting onto the resin molecular chain can undergo esterification with the hydroxyl groups in the polyether-hydroxyl silicone oil intermediate, forming a stable covalent bond. This allows "C5 resin-polyether-silicone oil" to form an integrated core defoaming unit, avoiding the separation of functional components and leveraging the spatial distribution advantages of the branched structure to ensure uniform dispersion of defoaming active sites, thereby improving efficiency.

[0043] The intermediate formed by the acid-catalyzed dehydration condensation of polyoxyethylene polyoxypropylene ether and hydroxyl silicone oil is the core source of the defoaming function: hydroxyl silicone oil, with its low surface tension, can quickly spread to the surface of the foam liquid film, disrupting the surface tension balance of the liquid film and causing the foam to break instantly; while polyoxyethylene polyoxypropylene ether, by regulating the hydrophilic-lipophilic balance value, enhances the dispersibility of the core defoaming unit in the water-oil two-phase system, avoids the aggregation of active components, and ensures that it can quickly penetrate into the foam to play its role.

[0044] Silane-modified nano-silica, after modification with γ-aminopropyltriethoxysilane, possesses high hydrophobic properties. Its nanoscale particle size allows it to adsorb onto the surface of the core defoaming unit, forming a synergistic effect of "chemical defoaming + physical puncture." When the core unit reduces the surface tension of the liquid film, the nanoparticles act as physical sites embedded in the liquid film, further exacerbating the non-uniformity of the liquid film and accelerating its rupture. At the same time, it inhibits the re-aggregation of the ruptured liquid film to form new foam. Polyglycerol fatty acid esters, as defoaming aids, can assist the core unit in forming a dense barrier film on the foam surface, delaying foam regeneration and prolonging the foam suppression time.

[0045] The beneficial effects of this invention are:

[0046] 1. This invention precisely designs the structure of a branched C5 resin, utilizing triallyl isocyanurate to construct a branched structure that breaks the molecular chain entanglement of traditional linear resins, significantly reducing intermolecular forces. Combined with the solvent-regulating effect of toluene, this ensures the defoamer maintains suitable flowability. Simultaneously, the functional components are covalently linked to form a highly compatible integrated system, preventing component aggregation and enabling rapid dispersion in a water-oil two-phase system. It can act uniformly on the foam area without additional dilution, adapting to the needs of various industrial production scenarios and improving application convenience.

[0047] 2. This invention constructs a synergistic system of "chemical defoaming + physical puncture." The covalent intermediate formed by polyoxyethylene polyoxypropylene ether and hydroxyl silicone oil retains the low surface tension characteristics of silicone oil, enabling rapid spreading and disruption of the foam liquid film balance. Simultaneously, the polyether regulates the hydrophilic-lipophilic balance, ensuring rapid penetration of the active component. The high hydrophobicity and nano-particle size of silane-modified nano-silica further exacerbate the liquid film inhomogeneity, accelerating foam rupture. This allows for the rapid elimination of large amounts of foam in a short time, preventing foam accumulation from affecting the production process and ensuring production continuity.

[0048] 3. The integrated unit of "C5 resin-polyether-silicone oil" formed by covalent bonding in this invention is not prone to migration and can continuously act on the foam system; the dense barrier film formed by polyglycerol fatty acid ester can effectively delay liquid film regeneration; at the same time, the branched structure improves the compatibility of components, and the silane-modified nano-silica avoids agglomeration and precipitation, so that the defoamer will not have problems such as layering, turbidity, or gelation during long-term storage under normal temperature and high and low temperature environments. It has strong performance stability and can maintain a long-term antifoaming effect, reducing the cost of frequent replenishment.

[0049] 4. This invention uses widely available and cost-effective C5 fraction as the core raw material. Through the design of grafting branched monomers with maleic anhydride, the reactivity of the raw material is enhanced, and unreacted monomer residue is reduced. The solvent used in the preparation process is easily removed by vacuum distillation, and the catalyst can be effectively removed by neutralization and filtration. The product has high purity and no additional harmful impurities are generated, conforming to the trend of green production. This defoamer is suitable for foam control needs in multiple fields such as fermentation, coatings, and petrochemicals, with a wide range of applications and strong practicality. Detailed Implementation

[0050] 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.

[0051] Preparation Example 1: The specific preparation method of branched C5 resin includes the following steps:

[0052] (1) Add triallyl isocyanurate to toluene to prepare a branched monomer solution with a concentration of 10 wt%. Dry maleic anhydride to a water content of <20 ppm and add it to toluene to prepare a maleic anhydride-toluene solution with a concentration of 5 wt%. The polymerization reactor is purged with nitrogen three times to ensure that the oxygen content in the reactor is <50 ppm.

[0053] (2) 100g of C5 fraction (40% isoprene, 22% 1,3-pentadiene, 25% cyclopentadiene, 8% n-pentene, 5% 2-pentene, and pretreated to a water content of <30ppm), 0.35g of dicumyl peroxide and 55g of toluene were added to the polymerization reactor. The mixture was heated to 110℃ with stirring. 12g of a 10wt% branched monomer solution was added dropwise over 45min. After the addition was completed, the reaction was kept at the temperature for 3h. The reaction system temperature was maintained at 110℃. 190g of a 5wt% acid anhydride-toluene solution was added dropwise over 1.5h. After the addition was completed, the reaction was kept at the temperature for 2h.

[0054] (3) Cool the system to 75°C and distill under reduced pressure to remove unreacted monomers and oligomers to obtain branched C5 resin.

[0055] Preparation Example 2: The specific preparation method of silane-modified nano-silica includes the following steps:

[0056] 100g of nano-silica (particle size 40-60nm) was added to 2kg of ethanol / water mixed solution (volume ratio of ethanol to water is 9:1). While stirring, 12g of γ-aminopropyltriethoxysilane was added, the temperature was raised to 65℃, and the reaction was carried out for 8h. The solid was collected by centrifugation, washed and dried to obtain silane-modified nano-silica.

[0057] Comparative Preparation Example 1: The difference between Comparative Preparation Example 1 and Preparation Example 1 is that the branched monomer solution is not added in step (2).

[0058] Comparative Preparation Example 2: The difference between Comparative Preparation Example 2 and Preparation Example 1 is that the amount of branched monomer solution added in step (2) is increased to 24g.

[0059] Comparative preparation example 3: The difference between comparative preparation example 3 and preparation example 1 is that maleic anhydride-toluene solution is not added in step (2).

[0060] Comparative Preparation Example 4: The difference between Comparative Preparation Example 4 and Preparation Example 1 is that in step (1), triallyl isocyanurate is replaced with pentaerythritol tetraacrylate.

[0061] Example 1: A specific preparation process for a low-viscosity, high-defoaming-efficiency C5 defoamer, comprising the following steps:

[0062] S1. Under nitrogen protection and with the coordinated control of DCS and SIS systems, 50g of hydroxyl silicone oil (hydroxyl content of 9.2%, number average molecular weight of 2000-2500), 20g of polyoxyethylene polyoxypropylene ether (EO / PO molar ratio of 1.5:1, number average molecular weight of 1500-2000), and 0.5g of p-toluenesulfonic acid were added to a reactor equipped with a water separator and a reflux condenser. 400g of xylene was added as an azeotropic solvent. The mixture was heated to 120℃ with stirring. When the DCS monitoring showed that the amount of water separated by the water separator was close to the theoretical value, the reaction endpoint was determined, heating was stopped, 0.05g of anhydrous sodium bicarbonate was added to the system, and the mixture was stirred for 30min. After filtration, the system was cooled to 80℃, and vacuum distillation was started to remove the solvent and unreacted low molecular weight polyether / hydroxyl silicone oil fragments to obtain a polyether-hydroxyl silicone oil intermediate.

[0063] S2. Under nitrogen protection and with the joint control of DCS and SIS systems, the polyether-hydroxy silicone oil intermediate, 100g of the branched C5 resin prepared according to Preparation Example 1, 1g of p-toluenesulfonic acid and 800g of xylene were added to a reaction vessel equipped with a water separator and a reflux condenser. The mixture was heated to 150°C with stirring. When the DCS detected that the amount of water separated by the water separator was close to the theoretical value, the reaction endpoint was determined, heating was stopped, 0.1g of anhydrous sodium bicarbonate was added to the system, and the mixture was stirred for 30min. After filtration, the system was cooled to 80°C, and vacuum distillation was started to remove the solvent and oligomers to obtain the defoamer intermediate.

[0064] S3. DCS control first adds 1kg of toluene as a base material to the mixing tank, heats it to 60℃, and then, through DCS settings, adds all the defoamer intermediates obtained in S2, 10g of silane-modified nano-silica, and 5g of polyglycerol fatty acid ester. The mixture is automatically added to the mixing tank, and the DCS starts the reducer, controlling the stirring speed at 600rpm for 20 minutes. Then, it is ultrasonically dispersed at 300W power for 20 minutes. After naturally cooling to room temperature, it is filtered through a 200-mesh filter to obtain a low-viscosity, high-efficiency C5 defoamer. Samples are taken for testing of appearance, kinematic viscosity, density, freezing point, and active ingredient content. After passing the tests, the product is packaged using an automatic filling system under programmable control, with dynamic weighing to control the net content error to ±0.5kg, and then stored in the warehouse. Non-conforming products are handled according to the non-conforming product control procedure.

[0065] Example 2: A specific preparation process for a low-viscosity, high-defoaming-efficiency C5 defoamer, comprising the following steps:

[0066] S1. Under nitrogen protection and with the joint control of DCS and SIS systems, 80g of hydroxyl silicone oil (hydroxyl content of 9.2%, number average molecular weight of 2000-2500), 30g of polyoxyethylene polyoxypropylene ether (EO / PO molar ratio of 1.5:1, number average molecular weight of 1500-2000) and 1.6g of p-toluenesulfonic acid were added to a reactor equipped with a water separator and a reflux condenser. 800g of xylene was added as an azeotropic solvent. The mixture was heated to 125℃ with stirring. When the DCS monitored that the amount of water separated by the water separator was close to the theoretical value, the reaction endpoint was determined, heating was stopped, 0.24g of anhydrous sodium bicarbonate was added to the system, and the mixture was stirred for 50min. After filtration, the system was cooled to 85℃, and vacuum distillation was started to remove the solvent and unreacted low molecular weight polyether / hydroxyl silicone oil fragments to obtain a polyether-hydroxyl silicone oil intermediate.

[0067] S2. Under nitrogen protection and with the joint control of DCS and SIS systems, the polyether-hydroxy silicone oil intermediate, 150g of the branched C5 resin prepared according to Preparation Example 1, 3g of p-toluenesulfonic acid and 1.5kg of xylene were added to a reactor equipped with a water separator and a reflux condenser. The mixture was heated to 145°C with stirring. When the DCS detected that the amount of water separated by the water separator was close to the theoretical value, the reaction endpoint was determined, heating was stopped, 0.45g of anhydrous sodium bicarbonate was added to the system, and the mixture was stirred for 45min. After filtration, the system was cooled to 85°C, and vacuum distillation was started to remove the solvent and oligomers to obtain the defoamer intermediate.

[0068] S3. DCS control first adds 1kg of toluene as a base material to the mixing tank, heats it to 70℃, and then, through DCS settings, adds all the defoamer intermediates obtained in S2, 20g of silane-modified nano-silica, and 8g of polyglycerol fatty acid ester. The mixture is automatically added to the mixing tank, and the DCS starts the reducer, controlling the stirring speed at 800rpm for 30 minutes. Then, it is ultrasonically dispersed at 350W power for 30 minutes. After naturally cooling to room temperature, it is filtered through a 200-mesh filter to obtain a low-viscosity, high-efficiency C5 defoamer. Samples are taken for testing of appearance, kinematic viscosity, density, freezing point, and active ingredient content. After passing the tests, the product is packaged using an automatic filling system under programmable control, with dynamic weighing to control the net content error to ±0.5kg, and then stored in the warehouse. Non-conforming products are handled according to the non-conforming product control procedure.

[0069] Example 3: A specific preparation process for a low-viscosity, high-defoaming-efficiency C5 defoamer, comprising the following steps:

[0070] S1. Under nitrogen protection and with the joint control of DCS and SIS systems, 100g of hydroxyl silicone oil (hydroxyl content of 9.2%, number average molecular weight of 2000-2500), 40g of polyoxyethylene polyoxypropylene ether (EO / PO molar ratio of 1.5:1, number average molecular weight of 1500-2000) and 3g of p-toluenesulfonic acid were added to a reactor equipped with a water separator and a reflux condenser. 1.2kg of xylene was added as an azeotropic solvent. The mixture was heated to 130℃ with stirring. When the DCS monitoring showed that the amount of water separated by the water separator was close to the theoretical value, the reaction endpoint was determined, heating was stopped, 0.5g of anhydrous sodium bicarbonate was added to the system, and the mixture was stirred for 60min. After filtration, the system was cooled to 90℃, and vacuum distillation was started to remove the solvent and unreacted low molecular weight polyether / hydroxyl silicone oil fragments to obtain a polyether-hydroxyl silicone oil intermediate.

[0071] S2. Under nitrogen protection and with the joint control of DCS and SIS systems, the polyether-hydroxy silicone oil intermediate, 200g of the branched C5 resin prepared according to Preparation Example 1, 6g of p-toluenesulfonic acid and 2.4kg of xylene were added to a reactor equipped with a water separator and a reflux condenser. The mixture was heated to 150°C with stirring. When the DCS detected that the amount of water separated by the water separator was close to the theoretical value, the reaction endpoint was determined, heating was stopped, 1g of anhydrous sodium bicarbonate was added to the system, and the mixture was stirred for 60min. After filtration, the system was cooled to 90°C, and vacuum distillation was started to remove the solvent and oligomers to obtain the defoamer intermediate.

[0072] S3. DCS control first adds 1kg of toluene as a base material to the mixing tank, heats it to 80℃, and then, through DCS settings, adds all the defoamer intermediates obtained in S2, 30g of silane-modified nano-silica, and 10g of polyglycerol fatty acid ester, which are automatically added to the mixing tank. DCS starts the reducer and controls the stirring speed to 1000rpm for 40min, followed by ultrasonic dispersion at 400W power for 40min. After natural cooling to room temperature, it is filtered through a 200-mesh filter to obtain a low-viscosity, high-defoaming-efficiency C5 defoamer. Samples are taken to test the appearance, kinematic viscosity, density, freezing point, and active ingredient content. After passing the test, it is packaged through an automatic filling system under program control, with dynamic weighing to control the net content error to ±0.5kg, and then stored in the warehouse. Non-conforming products are handled according to the non-conforming product control procedure.

[0073] Comparative Example 1: The difference between Comparative Example 1 and Example 2 is that the branched C5 resin prepared according to Preparation Example 1 is replaced with the branched C5 resin prepared according to Comparative Preparation Example 1.

[0074] Comparative Example 2: The difference between Comparative Example 2 and Example 2 is that the branched C5 resin prepared according to Preparation Example 1 is replaced with the branched C5 resin prepared according to Comparative Preparation Example 2.

[0075] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that the branched C5 resin prepared according to Preparation Example 1 is replaced with the branched C5 resin prepared according to Comparative Preparation Example 3.

[0076] Comparative Example 4: The difference between Comparative Example 4 and Example 2 is that the branched C5 resin prepared according to Preparation Example 1 is replaced with the branched C5 resin prepared according to Comparative Preparation Example 4.

[0077] Comparative Example 5: The difference between Comparative Example 5 and Example 2 is that the silane-modified nano-silica prepared according to Preparation Example 2 is replaced with nano-silica.

[0078] Comparative Example 6: The difference between Comparative Example 6 and Example 2 is that no polyglycerol fatty acid esters are added.

[0079] Performance testing:

[0080] 1.25℃ Viscosity Test: Take the defoamer products of each example and comparative example, place them in a 25℃ constant temperature water bath for 30 minutes to ensure that the sample temperature is consistent with the test environment. Use an NDJ-5S rotational viscometer, select rotor No. 2 or No. 3 according to the estimated viscosity range, set the rotation speed to 60 rpm, immerse the rotor vertically into the center of the sample, to the rotor mark line, and record the data after the instrument display value stabilizes for 1 minute. Each sample is tested in parallel 3 times, and the average value is taken as the final viscosity result. The experimental results are shown in Table 1.

[0081] 2. Bubble breaking time test: A Ross-Miles foam apparatus was used. 1000 mL of deionized water was added to the outer cylinder of the foam apparatus and heated to a constant temperature of 25°C. 50 mL of a 0.1% sodium dodecyl sulfate aqueous solution was added to the inner cylinder. The apparatus was turned on to circulate the water in the outer cylinder at a constant rate, impacting the solution in the inner cylinder to generate stable foam. The circulation was stopped immediately when the foam height reached 200 mm. 0.1 mL of the defoamer product from Examples 1-3 and Comparative Examples 1-6 was accurately added quickly using a pipette. At the same time, a stopwatch was started to record the time required for the foam to completely break (no obvious foam residue on the liquid surface). Each sample was tested in parallel three times, and the average value was taken as the bubble breaking time. The experimental results are shown in Table 1.

[0082] 3. Defoaming time test: A Ross-Miles foam apparatus was used. Before the test, 1000 mL of deionized water at 25°C and 50 mL of sodium dodecyl sulfate foaming solution with a mass fraction of 0.1% were prepared. The foaming solution was added to the inner cylinder of the foam apparatus, and an equal amount of 25°C deionized water was added to the outer cylinder. The instrument was turned on to allow the water in the outer cylinder to circulate and impact the foaming solution in the inner cylinder at a constant rate. At the same time, 0.1 mL of the defoamer products of Examples 1-3 and Comparative Examples 1-6 were accurately added. The circulation was maintained and the foam height was observed in real time. The time required from the start of circulation to the foam height reaching 100 mm for the first time was recorded as the defoaming time. Each sample was tested twice in parallel, and the average value was taken. The experimental results are shown in Table 1.

[0083] 4. Storage stability test: Take 50 mL of the defoamer product from each example and comparative example, put it into a transparent sealed glass bottle, and divide it into three groups for testing: the first group was placed in a room temperature (25℃) environment for 180 days, the second group was placed in a low temperature environment (-10℃) for 60 days, and the third group was placed in a high temperature environment (60℃) oven for 30 days. After storage, observe whether the samples show layering, turbidity, precipitation or gel particles. At the same time, test the viscosity change rate of the room temperature group samples (compared with the initial viscosity). If the viscosity change rate is ≤10% and there is no obvious appearance abnormality, it is judged to be stored stably. The experimental results are shown in Table 1.

[0084] Table 1 Performance Test Results

[0085]

[0086] Performance Analysis:

[0087] As can be seen from the experimental data in Table 1, the low-viscosity, high-defoaming-efficiency C5 defoamers prepared in Examples 1-3 according to the technical solution of the present invention show significant advantages in terms of viscosity at 25℃, defoaming efficiency, foam suppression time, and storage stability, which are superior to the comparative examples. This may be because the present invention has formed an integrated system of "low viscosity-high activity-long-term stability" by designing the structure of branched C5 resin, covalent synergistic effect of each functional component, and controlling the raw material ratio. This fully utilizes the synergistic effect of each component and avoids the performance degradation caused by defects of a single component or imbalance of process parameters.

[0088] The key to maintaining a stable low viscosity in this embodiment lies in the structural design of the branched C5 resin and the covalent synergistic effect of each component. This invention uses triallyl isocyanurate as the branching monomer, polymerizing it with the C5 fraction at a content of 0.8-1.5%. The resulting branched structure breaks the molecular chain entanglement problem of traditional linear resins, significantly reducing intermolecular forces. Simultaneously, maleic anhydride grafting introduces anhydride groups into the resin, forming a stable covalent bond with the hydroxyl groups of the polyether-hydroxyl silicone oil intermediate, constructing a highly compatible core defoaming unit. Combined with the uniform dispersion of silane-modified nano-silica and the solvent-regulating effect of toluene, the system maintains suitable fluidity throughout. In comparison, Comparative Example 1, lacking branched monomers, exhibited severe entanglement of linear C5 resin molecular chains, significantly enhancing intermolecular forces and resulting in a substantial increase in viscosity. Comparative Example 2, with its excessive addition of branched monomers, caused excessive cross-linking of the resin, leading to a dramatic increase in system viscosity. Comparative Example 3, lacking the maleic anhydride grafting step, prevented the resin from forming covalent bonds with the polyether-hydroxy silicone oil intermediate, reducing component compatibility and causing molecular aggregation, thus increasing viscosity. Comparative Example 4, using pentaerythritol tetraacrylate with a branching degree of 4 as the branched monomer, resulted in excessive cross-linking and aggregation of molecular chains due to its high branching degree, causing viscosity far exceeding the design range. Comparative Example 5, using unmodified nano-silica, exhibited hydrophilic properties that led to aggregation in the oil phase system, disrupting the uniform dispersion of the system and slightly increasing viscosity. Comparative Example 6, lacking only polyglycerol fatty acid esters, had a negligible effect on viscosity as an antifoaming agent, but due to its lack of dispersing properties, its viscosity was still slightly higher than the examples.

[0089] The excellent defoaming efficiency of the example is likely due to the fact that the covalent intermediate formed by the acid-catalyzed dehydration condensation of polyoxyethylene polyoxypropylene ether and hydroxyl silicone oil retains the low surface tension characteristics of silicone oil, enabling it to quickly spread to the surface of the foam liquid film and disrupt the tension balance. At the same time, the precise hydrophilic-lipophilic balance value controlled by the polyether ensures that the active components can quickly penetrate into the water-oil two-phase foam system. The branched structure of the branched C5 resin ensures that these defoaming active sites are evenly dispersed, avoiding agglomeration. The high hydrophobicity and nano-particle size of silane-modified nano-silica can be adsorbed on the surface of the core defoaming unit, embedded in the foam liquid film, exacerbating its non-uniformity and accelerating foam rupture. In Comparative Example 1, the linear resin resulted in uneven distribution of active sites, preventing the silicone oil and polyether from spreading rapidly to the liquid film, leading to a significant decrease in the defoaming rate. In Comparative Example 2, the over-branched resin created steric hindrance, encapsulating some active sites and hindering their effective contact with the foam liquid film, thus reducing the defoaming efficiency. In Comparative Example 3, the resin without maleic anhydride grafts lacked covalent bonding with the intermediates, making the components easily separable and unable to form an integrated defoaming unit, resulting in insufficient efficiency of the active components. In Comparative Example 4, the highly branched resin caused severe cross-linking, making it difficult for the defoaming unit to contact and act on the liquid film, significantly prolonging the defoaming time. In Comparative Example 5, the unmodified nano-silica aggregated, losing the synergistic effect of physical puncture and relying solely on chemical defoaming, resulting in insufficient efficiency. In Comparative Example 6, the absence of polyglycerol fatty acid esters had a smaller impact on the core defoaming effect, but due to the lack of dispersion aid, the penetration rate of the active components decreased slightly, and the defoaming rate was still lower than that of the examples.

[0090] The embodiment demonstrates long-lasting foam suppression capability, primarily due to the stable barrier and continuous action system formed by the various components. Polyglycerol fatty acid esters, acting as a defoaming aid, assist the core defoaming unit in forming a dense barrier film on the foam surface, delaying liquid film regeneration. The integrated unit formed by the covalent bonds of "C5 resin-polyether-silicone oil" is less prone to migration and can continuously act on the foam system. Silane-modified nano-silica can be adsorbed onto the liquid film surface for a long time, inhibiting the re-aggregation of the ruptured liquid film. Combined with the spatial distribution advantages of the branched resin, this further extends the foam suppression duration. In comparison, the linear resin in Comparative Example 1 had poor compatibility with the defoaming unit, easily detached from the liquid film surface, and could not continuously exert its inhibitory effect, resulting in a significantly shortened defoaming time. The over-branched resin in Comparative Example 2 was too rigid and could not flexibly spread on the liquid film to form a stable barrier layer, resulting in poor defoaming effect. The component without covalent bonding in Comparative Example 3 was prone to migration and could not continuously maintain the unstable state of the liquid film, resulting in the shortest defoaming time. The gel structure of Comparative Example 4 caused the defoaming unit to completely lose its activity and could not exert its inhibitory effect on newly formed foam, resulting in extremely poor defoaming ability. The unmodified nano-silica in Comparative Example 5 was prone to agglomeration and sedimentation, and the physical inhibitory effect gradually weakened over time, resulting in a shortened defoaming time. Due to the lack of polyglycerol fatty acid esters, Comparative Example 6 could not form a dense barrier film, and the liquid film easily re-aggregated to form new foam, resulting in a defoaming time much shorter than that of the examples.

[0091] The embodiments remained stable under both ambient and high / low temperature conditions, likely because the functional components were covalently linked to form a unified and stable system. The branched structure of the branched C5 resin improved its compatibility with the polyether-silicone oil intermediate, preventing component separation; the hydrophobic properties of the silane-modified nano-silica prevented it from agglomerating and precipitating in the system, ensuring stability under different environments. The linear resin in Comparative Example 1 exhibits strong intermolecular forces, making it prone to slight aggregation at low temperatures, resulting in slight turbidity and decreased stability. In Comparative Example 2, excessive branched monomers induce slow cross-linking, which is accelerated by high and low temperatures, ultimately leading to gelation, precipitation, and other failure phenomena. Comparative Example 3, lacking maleic anhydride grafting, suffers from extremely poor component compatibility, resulting in stratification due to density differences during storage, which is further exacerbated by high and low temperatures. Comparative Example 4, with its excessively high cross-linking density of highly branched resin, continues to gel and solidify during storage, rendering it unusable. Comparative Example 5, with its unmodified hydrophilic nano-silica, gradually aggregates and precipitates during storage, with precipitation becoming more pronounced at low temperatures. Although Comparative Example 6 lacks polyglycerol fatty acid esters, its core covalent system remains stable, resulting in no significant abnormalities in storage stability; however, due to the absence of stabilizing agents, its overall stability is slightly inferior to the examples.

[0092] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low-viscosity, high-defoaming-efficiency carbon-5 defoamer, characterized in that, The raw materials include the following parts by weight: branched C5 resin: 10-20 parts, hydroxyl silicone oil: 5-10 parts, polyoxyethylene polyoxypropylene ether: 2-4 parts, silane-modified nano silica: 1-3 parts, toluene: 100 parts, polyglycerol fatty acid ester: 0.5-1 parts; The branched C5 resin is prepared by free radical polymerization of C5 fraction and triallyl isocyanurate branched monomer, followed by grafting with maleic anhydride. The silane-modified nano-silica is prepared by modifying nano-silica with γ-aminopropyltriethoxysilane.

2. The low-viscosity, high-defoaming-efficiency C5 defoamer according to claim 1, characterized in that, The preparation method of the branched C5 resin includes the following steps: (1) Add triallyl isocyanurate to toluene to prepare a branched monomer solution. Dry maleic anhydride to a water content of <20ppm and add it to toluene to prepare a maleic anhydride-toluene solution. The polymerization reactor is purged with nitrogen three times to ensure that the oxygen content in the reactor is <50ppm. (2) Add the C5 fraction, dicumyl peroxide and toluene to the polymerization reactor, heat to 105-115℃ with stirring, add the branched monomer solution dropwise over 40-60 min, and keep the reaction temperature for 2-3 h after the addition is complete; keep the reaction temperature at 105-115℃, add maleic anhydride-toluene solution dropwise over 1-2 h, and keep the reaction temperature for 1-3 h after the addition is complete. (3) Cool the system to 70-80℃, reduce the pressure and distill to remove unreacted monomers and oligomers to obtain branched C5 resin.

3. The low-viscosity, high-defoaming-efficiency C5 defoamer according to claim 2, characterized in that, In step (1), the mass concentration of the branched monomer solution is 10%, and the mass concentration of the maleic anhydride-toluene solution is 5%.

4. The low-viscosity, high-defoaming-efficiency C5 defoamer according to claim 2, characterized in that, The C5 fraction in step (2) is composed of the following by weight percentage: 35-42% isoprene, 18-25% 1,3-pentadiene, 22-28% cyclopentadiene, 5-9% n-pentene, and 5-9% 2-pentene, and is pretreated by dehydration to a water content of <30ppm.

5. The low-viscosity, high-defoaming-efficiency C5 defoamer according to claim 2, characterized in that, In step (2), the C5 fraction, dicumyl peroxide, toluene, branched monomer solution and maleic anhydride-toluene solution are in a weight ratio of 100:0.25-0.5:50-60:8-15:140-240.

6. The low-viscosity, high-defoaming-efficiency C5 defoamer according to claim 1, characterized in that, The method for preparing the silane-modified nano-silica includes the following steps: Nano-silica was added to an ethanol / water mixture, and γ-aminopropyltriethoxysilane was added under stirring. The mixture was heated to 60-70℃ and reacted for 6-10 hours. The solid was collected by centrifugation, washed and dried to obtain silane-modified nano-silica.

7. The low-viscosity, high-defoaming-efficiency C5 defoamer according to claim 6, characterized in that, In the preparation method of silane-modified nano silica, the nano silica, ethanol / water mixed solution and γ-aminopropyltriethoxysilane are in a weight ratio of 1:10-30:0.08-0.15; the nano silica has a particle size of 40-60 nm, and the volume ratio of ethanol to water in the ethanol / water mixed solution is 9:

1.

8. The preparation process of the low-viscosity, high-defoaming-efficiency C5 defoamer according to any one of claims 1-7, characterized in that, The control system employs a combination of DCS (Distributed Control System) automation control program and SIS (Safety Automation System) safety automation control program, including the following steps: S1. Under nitrogen protection and with the linkage control of DCS and SIS systems, hydroxyl silicone oil, polyoxyethylene polyoxypropylene ether, and catalyst are added to a reactor equipped with a water separator and a reflux condenser. Xylene is added as an azeotropic solvent. The mixture is heated to 120-130℃ with stirring. When the DCS monitors that the amount of water separated by the water separator is close to the theoretical value, the reaction endpoint is determined, heating is stopped, anhydrous sodium bicarbonate is added to the system, and the mixture is stirred for 30-60 minutes. The mixture is then filtered, and the system is cooled to 80-90℃. Vacuum distillation is then started to remove the solvent and unreacted low-molecular-weight polyether / hydroxyl silicone oil fragments to obtain a polyether-hydroxyl silicone oil intermediate. S2. Under nitrogen protection and with the joint control of DCS and SIS systems, polyether-hydroxy silicone oil intermediate, branched C5 resin, catalyst and xylene are added to a reactor equipped with a water separator and reflux condenser. The mixture is heated to 140-150℃ with stirring. When the DCS monitors that the amount of water separated by the water separator is close to the theoretical value, the reaction endpoint is determined, heating is stopped, anhydrous sodium bicarbonate is added to the system, and the mixture is stirred for 30-60 minutes. After filtration, the system is cooled to 80-90℃, and vacuum distillation is started to remove the solvent and oligomers to obtain the defoamer intermediate. S3. DCS control first adds toluene as a base material to the mixing tank, heats it to 60-80℃, then the DCS sets the feeding amounts of defoamer intermediate, silane-modified nano-silica, and polyglycerol fatty acid ester, which are automatically added to the mixing tank. The DCS starts the reducer and controls the stirring speed to 600-1000 rpm for 20-40 minutes. Then, it is ultrasonically dispersed at 300-400W power for 20-40 minutes. After naturally cooling to room temperature, it is filtered through a 200-mesh filter to obtain a low-viscosity, high-defoaming-efficiency C5 defoamer. Samples are taken to test the appearance, kinematic viscosity, density, freezing point, and active ingredient content. After passing the test, it is packaged by programmable automatic filling system, with dynamic weighing to control the net content error to ±0.5kg, and then stored in the warehouse. Non-conforming products are handled according to the non-conforming product control procedure.

9. The preparation process of the low-viscosity, high-defoaming-efficiency C5 defoamer according to claim 8, characterized in that, The hydroxyl content of the hydroxyl silicone oil in S1 is 9.2%, and the number average molecular weight is 2000-2500; the EO / PO molar ratio of the polyoxyethylene polyoxypropylene ether is 1.5:1, and the number average molecular weight is 1500-2000; the weight ratio of hydroxyl silicone oil, catalyst, xylene and anhydrous sodium bicarbonate is 1:0.01-0.03:8-12:0.001-0.005; the catalyst is p-toluenesulfonic acid.

10. The preparation process of the low-viscosity, high-defoaming-efficiency C5 defoamer according to claim 8, characterized in that, In S2, the branched C5 resin, catalyst, xylene, and anhydrous sodium bicarbonate are in a weight ratio of 1:0.01-0.03:8-12:0.001-0.005; the catalyst is p-toluenesulfonic acid.

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