Polycarboxylic acid sodium salt dispersing agent based on N-(2-quinolyl) acrylamide and preparation method thereof

Abstract

The invention discloses a sodium polycarboxylic acid dispersant based on N-(2-quinolyl) acrylamide and a preparation method of the sodium polycarboxylic acid dispersant, and belongs to the technical field of preparation of rubber dispersants. The dispersing agent is prepared by carrying out free radical copolymerization on acrylic acid, maleic anhydride, a functional monomer A, a functional monomer B and N-(2-quinolyl) acrylamide in an organic solvent and then carrying out alkali neutralization. By introducing the N-(2-quinolyl) acrylamide functional monomer, the anchoring capacity and steric hindrance effect of the dispersant on rubber particles are remarkably improved, and the dispersant has good high temperature resistance and oxidation resistance. Meanwhile, the dispersant has fluorescence characteristics due to the existence of quinoline groups, can be used for monitoring the content of the dispersant and the adhesion condition of a glue solution in real time, and is beneficial to optimizing the production process flow of solution polymerized styrene-butadiene rubber and improving the product quality and stability.

Description

Technical Field

[0001] This application belongs to the field of rubber dispersant preparation technology, specifically relating to a sodium polycarboxylate dispersant based on N-(2-quinolinyl)acrylamide and its preparation method. Background Technology

[0002] Solution-polymerized styrene-butadiene rubber (SSBR) is produced continuously using butadiene and styrene as monomers and cyclopentane as solvent through anionic active polymerization. Its main process includes polymerization reaction, solution coagulation, solvent recovery, pressing and drying, and extrusion molding. In the solution coagulation stage, the polymerized solution is sprayed into a coagulation reactor, where unreacted monomers and solvents are stripped away. However, the rubber is prone to self-adhesion and agglomeration, trapping unremoved monomers and solvents, leading to glue buildup and blockages on the reactor walls and pipelines. In the rubber industry, solution coagulation during SSBR production is a critical factor affecting product quality and process stability; therefore, dispersants must be used to ensure uniform dispersion of the solution.

[0003] Despite the various coagulant solutions proposed by existing technologies, significant drawbacks still exist: While CN103304688A improves the granulation efficiency of powdered rubber by compounding polymer resins with metal salts, its preparation process requires 10-200 parts of organic solvent, posing certain toxicity and environmental risks. Furthermore, subsequent solvent recovery increases process complexity and cost. More critically, this system lacks functional group design, limiting its adaptability to latexes with high gel content or extreme Mooney viscosity, and it cannot monitor the dispersion state in real time.

[0004] CN107459660A emphasizes environmental friendliness, using renewable raw materials such as plant-based soybean oil and oleic acid. However, its core mechanism still relies on the physical compounding of traditional surfactants. The synergistic effect of sodium dodecyl sulfate and erucamide is limited to basic dispersion, lacking high-temperature stability and chemical anchoring ability. In the high-temperature stripping environment of continuous condensation in SSBR, its molecular structure is prone to degradation or desorption, leading to a decrease in dispersion efficiency. Furthermore, there are no online monitoring methods, resulting in delayed process adjustments.

[0005] CN109929143A discloses a dispersion system using liquid nitrogen, sulfuric acid, and liquid ammonia as components. This system involves multiple hazardous chemicals, requiring high safety standards for production operations. Furthermore, the chemical compatibility and long-term stability of the components in the formulation have not been fully verified. This dispersant only possesses basic demulsification functions and makes no substantial contribution to particle size distribution control, anti-adhesion, or equipment anti-fouling, thus having extremely low industrial application value.

[0006] CN114516924A focuses on low-saponification coagulation of NBR latex. While its inorganic salt-fatty alcohol-pH adjuster system effectively reduces organic acid content, it essentially relies on physical salting out and solvent extraction, resulting in a single-function approach. This system is unsuitable for the solvent-based adhesive environment of SSBR, and the evaporation and recovery of alcohol solvents consume significant energy. Precise pH control also increases operational complexity. Furthermore, this method still requires equipment sealing and corrosion resistance, and completely lacks the ability to monitor dispersant concentration and adhesive adhesion. Summary of the Invention

[0007] This application aims to provide a sodium polycarboxylate dispersant based on N-(2-quinolinyl)acrylamide and its preparation method. By introducing this functional monomer into the molecular structure, the dispersing performance is improved while real-time monitoring of the dispersant content and the accumulation of the adhesive solution is achieved.

[0008] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application provides a sodium polycarboxylate dispersant based on N-(2-quinolinyl)acrylamide, characterized in that it comprises, by weight parts: Acrylic acid: 30-40 parts; Maleic anhydride: 35-40 parts; Functional monomer A: 15-30 parts; Functional monomer B: 1-5 parts; N-(2-quinolinyl)acrylamide: 1-5 parts.

[0009] As a further improvement of this application, the functional monomer A is selected from one or more of 2,3,3-trimethyl-1-butene, 2-methyl-1-hexene, 2,4-dimethyl-1-hexene, 2,4,4-trimethyl-1-pentene, and 2,4,4-trimethyl-2-pentene.

[0010] As a further improvement to this application, the functional monomer B is selected from one or more of α-methylstyrene, vinylpyridine, acrylonitrile, and styrene.

[0011] As a further improvement to this application, the organic solvent is selected from one or more of benzene, toluene, xylene, and ethyl acetate.

[0012] In a second aspect, this application provides a method for preparing a sodium polycarboxylate dispersant based on N-(2-quinolinyl)acrylamide, used to prepare the sodium polycarboxylate dispersant based on N-(2-quinolinyl)acrylamide as described in any one of claims 1 to 4, characterized in that it comprises: An initiator solution is prepared by mixing an organic solvent, acrylic acid, functional monomer A, and an initiator. Maleic anhydride, N-(2-quinolinyl)acrylamide, and functional monomer B are added to a reaction vessel. After heating to the set temperature, the initiator solution is added dropwise to carry out the polymerization reaction. After the reaction is completed, an alkaline aqueous solution is added for neutralization. After neutralization, the mixture is allowed to stand and separate into layers. The lower liquid is the sodium polycarboxylate dispersant.

[0013] As a further improvement of this application, the mass ratio of the organic solvent to the monomer is (1.0–1.4):1.

[0014] As a further improvement to this application, the polymerization reaction temperature is 60–90°C and the reaction time is 2–6 h.

[0015] As a further improvement to this application, the alkaline aqueous solution is a sodium hydroxide, potassium hydroxide, or sodium carbonate solution.

[0016] As a further improvement to this application, the neutralization reaction temperature is 80–95°C and the reaction time is 6–8 h.

[0017] As a further improvement of this application, the initiator is one or more of hydrogen peroxide, azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide, and the amount of the initiator accounts for 0.5%-2.0% of the total mass of the monomer.

[0018] As a further improvement to this application, the polymerization reaction is carried out under nitrogen protection.

[0019] Thirdly, this application provides the application of a sodium polycarboxylate dispersant based on N-(2-quinolinyl)acrylamide in the solution polymerization process of styrene-butadiene rubber.

[0020] Compared with the prior art, this application has the following advantages: This application provides a sodium polycarboxylate dispersant based on N-(2-quinolinyl)acrylamide, prepared by free radical copolymerization of acrylic acid, maleic anhydride, functional monomer A, functional monomer B, and N-(2-quinolinyl)acrylamide in an organic solvent, followed by alkali neutralization. By introducing the N-(2-quinolinyl)acrylamide functional monomer, the dispersant's anchoring ability and steric hindrance effect on rubber particles are significantly improved, while also exhibiting good high-temperature resistance and antioxidant properties. Furthermore, the presence of the quinoline group gives the dispersant fluorescent properties, which can be used for real-time monitoring of dispersant content and adhesive adhesion, helping to optimize the solution polymerization process of styrene-butadiene rubber and improve product quality and stability. Attached Figure Description

[0021] Figure 1 Infrared spectrum of the sample prepared for Example 6 of this application. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0024] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0025] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0026] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0027] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as µg, mg, g, or kg.

[0028] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0029] In rubber production, dispersants are added to a coagulation reactor, where they are vaporized, condensed, and then recovered and recycled. Currently, there is a lack of effective methods for detecting and monitoring the dispersant content in the recovery system. As operating time increases, rubber residue tends to accumulate on the inner wall of the coagulation reactor, affecting process stability and product quality.

[0030] The inventors discovered that polycarboxylate dispersants exhibit excellent dispersion effects during rubber coagulation, and based on this, obtained a novel rubber dispersant with superior performance. The anionic carboxylate group (RCOO) in the polycarboxylate... - The dispersant adsorbs onto the surface of rubber particles through electrostatic attraction, forming a hydrophilic layer, reducing surface tension, thereby inhibiting particle aggregation, increasing specific surface area, and promoting the diffusion of residual monomers and solvents from the interior to the surface. Its long-chain structure can form a steric hindrance layer around the particles, preventing particle re-aggregation during stripping, reducing adhesion, and significantly improving dispersion. The inventors introduced N-(2-quinolinyl)acrylamide into the dispersant, utilizing the fluorescent properties of its quinolinyl group, enabling online monitoring of the dispersant content and adhesive adhesion in the recovery system via fluorescence detection.

[0031] The technical solution of this application is as follows: an initiator solution is prepared by mixing an organic solvent, acrylic acid, functional monomer A and an initiator; maleic anhydride, N-(2-quinolinyl)acrylamide and functional monomer B are added to a reaction vessel, and after heating to a specified temperature, the initiator solution is added at a constant rate to carry out a polymerization reaction; after the reaction is completed, an alkaline aqueous solution is added to carry out a neutralization reaction, and after neutralization is completed, the mixture is allowed to stand and separate into layers, and the lower layer of sodium polycarboxylate dispersant solution is collected.

[0032] Among them, acrylic acid: 30-40 parts; maleic anhydride: 35-40 parts; the molar ratio of maleic anhydride to acrylic acid is 1:(1.0-1.5); the amount of functional monomer A is 15-30 parts; the amount of functional monomer B is 1-5 parts; the amount of N-(2-quinolinyl)acrylamide is 1-5 parts. In some embodiments, the polymerization reaction temperature is 60–90°C and the time is 2–6 h; the neutralization reaction temperature is 80–95°C and the time is 6–8 h. Furthermore, functional monomer A is selected from one or more of 2,3,3-trimethyl-1-butene, 2-methyl-1-hexene, 2,4-dimethyl-1-hexene, 2,4,4-trimethyl-1-pentene, and 2,4,4-trimethyl-2-pentene; functional monomer B is selected from one or more of α-methylstyrene, vinylpyridine, acrylonitrile, and styrene; the initiator is one or more of hydrogen peroxide, azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide; the organic solvent is one or more of benzene, toluene, xylene, and ethyl acetate; and the alkaline aqueous solution is sodium hydroxide, potassium hydroxide, or sodium carbonate solution.

[0033] In some embodiments, the total mass ratio of solvent to monomer is (1.0–1.4):1; the polymerization reaction is carried out under a nitrogen atmosphere.

[0034] The principle is as follows: the quinoline ring in N-(2-quinolinyl)acrylamide can be anchored to the surface of rubber particles through chemisorption and π–π stacking. Its rigid structure enhances the steric hindrance effect and improves heat resistance. The quinoline structure has antioxidant capabilities, which can reduce the degree of thermo-oxidative aging of the rubber solution during high-temperature stripping. Based on its fluorescence properties, ultraviolet light detection can be used to achieve online monitoring of dispersant content and rubber solution adhesion. In addition, the N–H and C=O in the amide group can act as hydrogen bond donors and acceptors, respectively, forming hydrogen bonds with the particles, enhancing interfacial bonding and reducing dispersant desorption. The amide and carboxyl groups together constitute multiple adsorption sites (hydrogen bonds and electrostatic adsorption), which can enhance the electronic delocalization effect of the quinoline group and further improve antioxidant performance.

[0035] This application optimizes the molecular structure of the dispersant by introducing N-(2-quinolinyl)acrylamide, enhancing its anchoring ability and steric stabilization effect on rubber particles, and improving its high-temperature resistance and resistance to thermo-oxidative aging. Simultaneously, this dispersant possesses fluorescent properties, allowing for online monitoring of its content and adhesive adhesion via ultraviolet spectroscopy. Specifically: (1) Multiple anchoring mechanisms are obtained through molecular structure design. Specifically, N-(2-quinolinyl)acrylamide functional monomers are introduced into the polycarboxylic acid backbone, which endows the dispersant with unprecedented multiple action capabilities. The quinoline ring can be adsorbed onto the surface of rubber particles through a strong π-π stacking effect, while its amide group (-NH-C=O) acts as both a hydrogen bond donor and acceptor, forming a strong hydrogen bond network with the polar groups on the particle surface. Combined with the electrostatic repulsion of the polycarboxylic acid itself, a triple anchoring and stabilization mechanism of "π-π stacking + hydrogen bonding + electrostatic stability" is formed, which greatly improves the anti-desorption ability and dispersion persistence under high temperature and high shear environment.

[0036] (2) The quinoline group, as a natural fluorescent chromophore, endows this dispersant with strong and stable fluorescence properties. This property represents a revolutionary leap from "invisible" to "visible," allowing for real-time and precise monitoring of the concentration changes of the dispersant in the circulation system and its adhesion to equipment surfaces via an online ultraviolet spectrometer. This provides direct data support for preventing adhesive buildup, optimizing dosing strategies, and achieving predictive maintenance—a key function that no traditional dispersant can achieve. Therefore, it possesses the advantages of built-in fluorescence tracer and process visualization.

[0037] (3) The rigid conjugated large π bond structure of the quinoline ring endows the molecular chain with extremely high thermal stability, making it difficult to break and decompose under high-temperature stripping conditions. At the same time, this structure has good antioxidant capacity, which can effectively quench free radicals and slow down the thermo-oxidative aging phenomenon of the adhesive during high-temperature processes. This not only protects the rubber molecular chain, but also extends the service life of the dispersant itself and reduces consumption.

[0038] (4) By adjusting the types and ratios of functional monomer A (such as various olefins) and functional monomer B (such as styrene derivatives), the molecular weight, chain rigidity, and hydrophilic-lipophilic balance (HLB) of the polymer can be precisely controlled. This allows for customized design of SSBR solutions with different Mooney viscosities, gel contents, and solvent systems, demonstrating excellent versatility and flexibility. Furthermore, in practical applications, it has been found that this dispersant can also be used with other rubbers, such as ABS, acrylate rubbers, and nitrile rubbers, demonstrating its wide applicability.

[0039] (5) The solvents used in the synthesis process of this dispersant (such as toluene and ethyl acetate) can be recycled through simple separation and recovery, and the final product is a water-soluble sodium salt that is non-toxic and harmless. Its high dispersion efficiency, anti-consumption characteristics, and precise dosing through online monitoring can reduce excessive use and waste from the source, and the overall cost of use is lower than that of traditional solutions.

[0040] In summary, this application is not a simple improvement on the existing technology, but an improvement in the dimensions of mechanism of action, functional integration and process control. It successfully solves the core problems that have long existed in the SSBR coagulation process, such as online monitoring, high temperature stability and formula universality, and has significant novelty, inventiveness and industrial application value.

[0041] The following description is based on specific embodiments.

[0042] Example 1 An initiator solution was prepared by dissolving 34 parts acrylic acid, 25 parts functional monomer A (2,4,4-trimethyl-1-pentene), and 1.0% azobisisobutyronitrile (AIBN) by mass in toluene. 37 parts maleic anhydride, 1 part N-(2-quinolinyl)acrylamide, and 3 parts functional monomer B (α-methylstyrene) were added to a reactor equipped with a stirrer, thermometer, and condenser. Nitrogen gas was purged to remove air, and the temperature was raised to 70°C. The initiator solution was then added dropwise at a uniform rate over 4 hours, and the reaction was maintained at this temperature for 4 hours. After the reaction was complete, an equimolar amount of 30% sodium hydroxide solution (equal to the carboxyl group) was added, and the mixture was stirred at 80°C for 6 hours to neutralize. The reaction solution was allowed to cool to room temperature, and the lower aqueous phase was collected by separation. This was the target sodium polycarboxylate dispersant product, a light yellow homogeneous liquid with a molecular weight between 8000 and 11000 and a viscosity of 30 mPa·s.

[0043] Example 2 An initiator solution was prepared by dissolving 30 parts acrylic acid, 30 parts functional monomer A (2,3,3-trimethyl-1-butene), and 0.8% benzoyl peroxide (by mass of the total monomers) in xylene. 35 parts maleic anhydride, 2 parts N-(2-quinolinyl)acrylamide, and 3 parts functional monomer B (vinylpyridine) were added to a reactor equipped with a stirrer, thermometer, and condenser. Under nitrogen protection, the mixture was heated to 60°C, and the initiator solution was added dropwise at a uniform rate over 2 hours. The reaction was maintained at this temperature for 6 hours. After the reaction was complete, an equimolar amount of 25% potassium hydroxide solution (equal to the carboxyl group) was added, and the mixture was stirred at 85°C for 8 hours to neutralize. The reaction solution was allowed to cool to room temperature, and the lower aqueous phase was collected to obtain the target sodium polycarboxylate dispersant product. This product is a light yellow homogeneous liquid with a molecular weight between 8000 and 11000 and a viscosity of 32 mPa·s.

[0044] Example 3 An initiator solution was prepared by dissolving 32 parts acrylic acid, 25 parts functional monomer A (2-methyl-1-hexene), and 1.2% azobisisobutyronitrile (1.2% by mass of the total monomers) in a mixed solvent of toluene and ethyl acetate (mass ratio 1:1). 35 parts maleic anhydride, 3 parts N-(2-quinolinyl)acrylamide, and 2 parts functional monomer B (acrylonitrile) were added to a reaction vessel under nitrogen protection. The temperature was raised to 75°C, and the initiator solution was added dropwise at a uniform rate over 3 hours, maintaining the reaction temperature for 4 hours. After the reaction was completed, a 20% sodium carbonate solution (equivalent to the carboxyl group) was added, and the mixture was stirred at 90°C for 7 hours to neutralize. The reaction solution was allowed to stand and cool to room temperature, and the lower aqueous phase was collected by separation to obtain the sodium polycarboxylate dispersant product. This product is a light yellow homogeneous liquid with a molecular weight between 8000 and 11000 and a viscosity of 31 mPa·s.

[0045] Example 4 An initiator solution was prepared by dissolving 36 parts acrylic acid, 20 parts functional monomer A (2,4-dimethyl-1-hexene), and 1.5% hydrogen peroxide (by mass of the total monomers) in benzene. 38 parts maleic anhydride, 4 parts N-(2-quinolinyl)acrylamide, and 4 parts functional monomer B (styrene) were added to a reactor under nitrogen protection. The temperature was raised to 80°C, and the initiator solution was added dropwise at a uniform rate over 5 hours, maintaining the reaction temperature for 3 hours. After the reaction was complete, an equimolar amount of 30% sodium hydroxide solution (equal to the carboxyl group) was added, and the mixture was stirred at 85°C for 6 hours to neutralize. The reaction solution was allowed to cool to room temperature, and the lower aqueous phase was collected by separation to obtain the sodium polycarboxylate dispersant product. This product is a light yellow homogeneous liquid with a molecular weight between 8000 and 11000 and a viscosity of 35 mPa·s.

[0046] Example 5 An initiator solution was prepared by dissolving 38 parts of acrylic acid, 18 parts of functional monomer A (2,4,4-trimethyl-2-pentene), and 2.0% azobisisobutyronitrile (AIBN) by mass in xylene. 40 parts of maleic anhydride, 4 parts of N-(2-quinolinyl)acrylamide, and 1 part of functional monomer B (α-methylstyrene) were added to a reaction vessel under nitrogen protection. The mixture was heated to 90°C, and the initiator solution was added dropwise at a uniform rate over 4.5 hours. The reaction was maintained at this temperature for 2 hours. After the reaction was complete, an equimolar amount of 28% sodium hydroxide solution was added, and the mixture was stirred at 95°C for 6.5 hours to neutralize the reaction. The reaction solution was allowed to cool to room temperature, and the lower aqueous phase was collected to obtain the sodium polycarboxylate dispersant product. This product is a light yellow homogeneous liquid with a molecular weight between 8000 and 11000 and a viscosity of 31 mPa·s.

[0047] Example 6 An initiator solution was prepared by dissolving 40 parts acrylic acid, 15 parts functional monomer A (a mixture of 2,4,4-trimethyl-1-pentene and 2,4-dimethyl-1-hexene), and 0.5% benzoyl peroxide (by mass of the total monomers) in ethyl acetate. 37 parts maleic anhydride, 5 parts N-(2-quinolinyl)acrylamide, and 3 parts functional monomer B (a mixture of vinylpyridine and styrene in a 1:1 mass ratio) were added to a reaction vessel under nitrogen protection. The temperature was raised to 70°C, and the initiator solution was added dropwise at a uniform rate over 6 hours, maintaining the reaction temperature for 5 hours. After the reaction was complete, an equimolar amount of 22% potassium hydroxide solution (equal to the carboxyl group) was added, and the mixture was stirred at 80°C for 8 hours to neutralize. The reaction solution was allowed to stand and cool to room temperature, and the lower aqueous phase was collected by separation to obtain the sodium polycarboxylate dispersant product. This product is a light yellow homogeneous liquid with a molecular weight between 8000 and 11000 and a viscosity of 34 mPa·s.

[0048] Comparative Example The conventional sodium polycarboxylate dispersant (without N-(2-quinolinyl)acrylamide structural units) was used. The raw material composition and preparation conditions were the same as in Example 3, but N-(2-quinolinyl)acrylamide was not added, and the amount of functional monomer A was increased accordingly.

[0049] This application provides a concept and method for a high-performance rubber dispersant and its preparation. There are many methods and approaches to implement this technical solution. The above is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application. These improvements and modifications should also be considered within the scope of protection of this application. All components not explicitly stated in this embodiment can be implemented using existing technology.

[0050] The performance of the samples prepared in Examples 1-6 and the comparative examples was evaluated as follows: (1) Evaluation of dispersion performance First, add the pre-prepared coagulation mother liquor to the coagulator, start stirring, and add the coagulant solution. Then, add the measured latex in several portions according to the coagulation progress, recording the coagulation time and particle size. Filter the coagulated particles and determine the oil content in the latex. Keep a sample of the filtered slurry for analysis and testing of its COD and other indicators.

[0051] Table 1. Comparison of dispersion effects of dispersants in Examples 1-6 with those in comparative examples.

[0052] Note: The data in the table are the test results of each sample at a uniform concentration of 40 ppm, used to compare relative efficacy, rather than the optimal efficacy concentration of each example sample.

[0053] As shown in Table 1, the sodium polycarboxylate dispersant based on N-(2-quinolinyl)acrylamide provided in this application exhibits comprehensive and significantly superior performance compared to traditional dispersants in terms of coagulation efficiency, colloidal morphology control, clear liquid separation effect, environmental impact reduction, and product purity improvement. Its enhanced overall performance provides a reliable technical solution for the efficient and clean production of solution-polymerized styrene-butadiene rubber.

[0054] (2) The N-(2-quinolinyl)acrylamide unit introduced in this product, with its quinoline group serving as an intrinsic fluorescent probe, provides a solid scientific basis for process analysis techniques (PAT). As described in the invention, bright visible fluorescence can be observed when the dried dispersant solid sample is excited in a dark room using an ultraviolet light source with a wavelength of 254 nm or 365 nm. This strong fluorescence response originates from the characteristic luminescence of the quinoline group in the N-(2-quinolinyl)acrylamide structure.

[0055] Therefore, the aqueous solutions of the pure dispersants in Examples 1-6 were first scanned using a fluorescence spectrophotometer. All products in the examples showed typical fluorescence characteristics of the quinoline group, with the maximum excitation wavelength (λex) stably located around 355 nm and the maximum emission wavelength (λem) located around 450 nm. Next, 5g of the dispersant product was weighed and kept at 105℃ for 2 hours. The dried dispersant solid was then dissolved in deionized water to prepare a standard solution with a wide range (1-500 ppm). A standard working curve was established between fluorescence intensity and dispersant concentration. This curve showed a good linear relationship (R²>0.999), ensuring the accuracy of quantitative analysis. The method detection limit (LOD) calculated based on the 3σ rule was as low as 0.8-1.5 ppm, indicating that the dispersant has extremely high detection sensitivity and fully meets the requirements of industrial online monitoring for trace analysis.

[0056] Table 2 shows the relationship between fluorescence intensity and dispersant concentration obtained after detection, based on the fluorescence characteristics of samples in Examples 1-6 above. All data are in λ... ex =355 nm, λ em The results were obtained using a fluorescence spectrophotometer at a wavelength of 450 nm.

[0057] Table 2. Relationship between fluorescence intensity and dispersant concentration for Examples 1-6 and comparative samples.

[0058] This data table confirms that the instantaneous concentration of dispersant in the system can be calculated accurately and in real time using simple fluorescence intensity detection. This provides a direct and reliable data foundation for achieving closed-loop intelligent control and early fault warning of dispersant dosing in industrial plants.

[0059] Therefore, high-temperature and chemically resistant online fluorescence detection probes can be installed on the inlet / outlet pipelines or circulation lines of the condensation reactor. The optical system must be precisely matched with a 355 nm excitation light source and a 450 nm emission detector. The real-time fluorescence signal captured by the probe is transmitted to the process control system (such as a DCS). The system automatically converts the fluorescence intensity into the instantaneous concentration value of the dispersant based on a built-in standard curve. By comparing the real-time concentration data with the set value, the system automatically adjusts the addition rate of the dispersant metering pump to ensure that the concentration is always within the optimal process window, achieving precise dosing and cost control. The system can also set a low concentration alarm threshold. Once an abnormally rapid drop in concentration is detected, it can immediately warn of potential faults such as equipment scaling, excessive dispersant adsorption, or pipeline blockage, providing crucial data support for predictive maintenance and ensuring production continuity and stability.

[0060] The infrared spectral analysis of the sample in Example 6 is shown below. Figure 1 The infrared spectrum of the sample, from... Figure 1 The following information can be seen: (1) Quinoline aromatic heterocycle: C=C, C=N at 1600cm -1 Peak emergence; (2) The out-of-plane bending vibration of the CH group of the benzene ring at 845 cm⁻¹ -1 Peak emergence; (3) The NH bending vibration and CN stretching vibration of the amide group are coupled at 1560.94 cm⁻¹ -1 Peak value; C=O stretching vibration at 1620 cm⁻¹ -1 Peak value, 1640~1680cm -1 The locations of these areas overlap, and the peaks in the graph are not obvious. (4) The symmetric stretching vibration of the carboxylate group -COO at 1409 cm⁻¹ -1 Peak emergence; (5) The polymer backbone -CH stretching vibration at 2953 cm⁻¹ -1 Peak emergence; (6) If the sample contains water or incompletely neutralized carboxylic acids, it will be present at 3500 cm⁻¹. -1 A very broad absorption band of -OH stretching vibration appears nearby, i.e. Figure 1 3402cm -1 Location: wide peak.

[0061] In summary, it can be demonstrated that the typical product is the sodium polycarboxylate of N-(2-quinolinyl)acrylamide.

[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A polycarboxylate sodium salt dispersant based on N-(2-quinolinyl) acrylamide characterized in that, By mass fraction, comprising: Acrylic acid: 30-40 parts; Maleic anhydride: 35-40 parts; Functional monomer A: 15-30 parts; Functional monomer B: 1-5 parts; N-(2-quinolinyl) acrylamide: 1-5 parts.

2. The polycarboxylate dispersant based on sodium salt of N-(2-quinolinyl) acrylamide according to claim 1, characterized in that, The functional monomer A is selected from one or more of 2,3,3-trimethyl-1-butene, 2-methyl-1-hexene, 2,4-dimethyl-1-hexene, 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene.

3. A polycarboxylate dispersant based on sodium salt of N-(2-quinolinyl) acrylamide according to claim 1, and a process for its preparation, characterized in that, The functional monomer B is selected from one or more of α-methylstyrene, vinylpyridine, acrylonitrile and styrene.

4. A polycarboxylate dispersant based on sodium salt of N-(2-quinolinyl) acrylamide according to claim 1, and a process for the preparation thereof, characterized in that, The organic solvent is selected from one or more of benzene, toluene, xylene and ethyl acetate.

5. A process for the preparation of a sodium salt of a polycarboxylate dispersant based on N-(2-quinolyl)acrylamide, for the preparation of a sodium salt of a polycarboxylate dispersant based on N-(2-quinolyl)acrylamide according to any one of claims 1 to 4, characterized in that, Comprising: An organic solvent, acrylic acid, functional monomer A and an initiator are formulated into an initiator solution; maleic anhydride, N-(2-quinolinyl) acrylamide and functional monomer B are added to a reaction kettle, the temperature is raised to a set temperature, then the initiator solution is added dropwise, and a polymerization reaction is carried out; after the reaction is completed, an aqueous alkali solution is added for a neutralization reaction, after the neutralization is completed, the mixture is left to stand and separate into layers, and the obtained lower liquid is a polycarboxylic acid sodium salt dispersant.

6. A polycarboxylate dispersant based on sodium salt of N-(2-quinolinyl) acrylamide according to claim 5, characterized in that, The mass ratio of the organic solvent to the monomers is (1.0-1.4):1; wherein the monomers are the sum of the functional monomer A and the functional monomer B; the amount of the initiator is 0.5%-2.0% of the total mass of the monomers.

7. A process for the preparation of a polycarboxylate sodium salt dispersant based on N-(2-quinolinyl) acrylamide according to claim 5, characterized in that, The polymerization reaction temperature is 60-90℃, and the reaction time is 2-6 h; The neutralization reaction temperature is 80-95℃, and the reaction time is 6-8 h.

8. The method of claim 5, wherein the preparation of a polycarboxylate sodium salt dispersant based on N-(2-quinolinyl) acrylamide is characterized by, The aqueous alkali solution is a sodium hydroxide, potassium hydroxide or sodium carbonate solution; The initiator is one or more of hydrogen peroxide, azobisisobutyronitrile, azobisisoheptyl nitrile and benzoyl peroxide.

9. The polycarboxylic acid sodium salt dispersant according to claim 5, wherein, The polymerization reaction is carried out under nitrogen protection.

10. Use of the N-(2-quinolinyl) acrylamide-based polycarboxylic acid sodium salt dispersant according to any one of claims 1-4 in the coagulation process of solution polymerized styrene-butadiene rubber.

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