High-purity resin white ball as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer material synthesis, and particularly relates to a high-purity resin white ball as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) carrying out raw material purification on styrene and divinylbenzene through an adsorption column filled with alkaline aluminum oxide; (2) mixing the purified raw materials in the step (1) with an initiator to obtain an oil phase, adding the oil phase into a water phase containing polyvinyl alcohol, stirring to form liquid drops with uniform size, slowly heating, and reacting at 75-85 DEG C to obtain resin white balls; and (3) alternately soaking the resin white ball prepared in the step (2) in a good solvent and a poor solvent for multiple times, and drying to obtain the high-purity resin white ball. The problems that existing resin white balls are insufficient in purity and high in organic dissolved matter content are effectively solved, and a high-quality base material is provided for high-performance functional resin.

Description

Technical Field

[0001] This invention belongs to the field of polymer material synthesis technology, specifically relating to a high-purity resin white ball, its preparation method, and its application. Background Technology

[0002] Cross-linked polystyrene resin white spheres, as an important polymer material, are widely used in ion exchange, drug carriers, and extreme experimental environments due to their excellent chemical stability (pH 1-14 tolerance), high mechanical strength, good thermal stability (thermal decomposition temperature above 350℃), and surface modifiability (e.g., introducing sulfonic acid groups, amino groups, etc.). However, their commercial application faces significant challenges: During transportation and storage, chemical additives such as polymerization inhibitors and antioxidants are required for the raw materials styrene and divinylbenzene. These impurities can be directly introduced into the polymerization system, affecting the purity and swelling properties of the resin white spheres. Furthermore, the free radical polymerization process itself is polydisperse, inevitably generating impurities such as oligomers, linear polymers, and initiator decomposition products. These impurities not only increase the organic leaching of the resin but also reduce key performance parameters of functional resins based on it, such as exchange capacity and crushing strength. Existing purification techniques, such as vacuum distillation, can partially remove impurities from the raw materials, but the heating process easily induces self-polymerization of the raw materials, increasing costs and raw material losses, and cannot effectively remove byproducts generated during polymerization.

[0003] Existing technologies disclose some methods for removing impurities from ion exchange resins; however, these methods suffer from insufficient purity and inadequate TOC levels.

[0004] CN 117264104 A discloses a nuclear-grade cation exchange resin and its preparation method. By purifying raw materials styrene, divinylbenzene and a third monomer, uniform white spheres are prepared by spray spheroidization, and then high-strength nuclear-grade cation exchange resin is obtained by sulfonation reaction. However, it has the problem of many types of raw materials, which leads to more residual impurities and requires more complicated post-processing purification.

[0005] CN 117700296 A discloses a method for removing ineffective impurities from white sphere raw materials. It uses an exchange column of gel strong base styrene anion resin or macroporous strong base anion resin to dynamically adsorb and remove impurities from styrene and divinylbenzene. The TOC of the resin made from the purified divinylbenzene is 14 ppm, which is insufficient for purification depth.

[0006] CN 117582963 A discloses a nuclear-grade resin, its purification method, and its application. The method involves soaking in an organic solvent, washing with hot water, and undergoing a conversion treatment with an electronic-grade acid / alkali solution to prepare a nuclear-grade resin with low metal impurity content, which can be used for the purification of primary loop water in nuclear power plants. It primarily addresses the issues of metal ion impurities and organic leachates, achieved through acid / alkali conversion and hot water washing, resulting in a TOC < 10 mg / L.

[0007] Therefore, developing a high-purity resin white ball that can simultaneously solve the problems of raw material purification and by-product removal while further reducing TOC, and its preparation method, is of great significance for improving the performance of functional resins and expanding their application range. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art by combining innovative raw material purification methods with efficient post-processing techniques. This aims to significantly reduce the content of organic impurities in resin white beads, thereby obtaining a high-purity product with a total organic carbon (TOC) leaching of less than 1 mg / L, in order to meet the stringent requirements for the purity of matrix materials in applications such as high-performance ion exchange resins.

[0009] Therefore, a first aspect of the present invention provides a method for preparing high-purity resin white spheres, the method comprising: (1) Styrene and divinylbenzene are purified by passing them through an adsorption column packed with alkaline alumina; (2) The raw material purified in step (1) is mixed with the initiator to obtain an oil phase. The oil phase is added to the aqueous phase containing polyvinyl alcohol. After stirring to form uniformly sized droplets, the temperature is slowly increased and reacted at 75~85℃ to obtain resin white balls. (3) After repeatedly soaking the resin white balls prepared in step (2) in good solvent and bad solvent, dry them to obtain high-purity resin white balls.

[0010] In the above-mentioned method for preparing high-purity resin white spheres, step (3) involves a post-treatment process of alternating soaking in good and bad solvents. Through the "displacement effect" of swelling and shrinkage, impurities such as oligomers in the polymer network are deeply removed to obtain high-purity resin white spheres. This preparation method employs a technical scheme of step (1) alkaline alumina adsorption column raw material purification + step (2) specific preparation process + step (3) alternating soaking in good and bad solvents, which can ensure that the total organic carbon released by the high-purity resin white spheres after soaking in water for 48 h is less than 1 mg / L.

[0011] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white balls, in step (2), the content of each component in the oil phase by mass percentage is as follows: initiator 0.4%~1.5%, styrene 89%~95.6%, and divinylbenzene 3.9%~10%. The content of the initiator within this range can effectively control the rate of free radical polymerization reaction, neither too fast leading to runaway reaction nor too slow affecting production efficiency; an appropriate amount of initiator can reduce the generation of by-products, such as oligomers and linear polymers, thereby improving the purity of the final product. Styrene is the main component of resin white balls, and an appropriate proportion ensures the basic properties of the resin, such as mechanical strength and chemical stability; the proportion coordinated with divinylbenzene ensures that the resin has an appropriate degree of crosslinking, which not only guarantees the mechanical strength of the resin but also maintains good swelling performance. As a crosslinking agent, an appropriate amount of divinylbenzene can increase the degree of crosslinking of the resin, enhance the mechanical strength and thermal stability of the resin; an appropriate proportion can avoid the increase in brittleness and decrease in swelling performance caused by excessive crosslinking.

[0012] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white balls, in step (2), the initiator is azobisisobutyronitrile (AIBN) or benzoyl peroxide. AIBN is a commonly used free radical initiator with good stability and activity, capable of effectively initiating polymerization reactions over a wide temperature range; compared to other initiators, AIBN has lower toxicity and higher operational safety. Benzoyl peroxide is a highly efficient free radical initiator, capable of initiating polymerization reactions at lower temperatures, improving reaction efficiency; benzoyl peroxide is suitable for various polymerization reactions, exhibiting good versatility and reliability.

[0013] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white spheres, in step (2), the mass fraction of polyvinyl alcohol in the aqueous phase is 0.1%~4%. As an emulsifier, an appropriate amount of polyvinyl alcohol can effectively stabilize the dispersion of the oil phase in the aqueous phase, forming uniformly sized droplets and ensuring the uniformity of the polymerization reaction; an appropriate amount of polyvinyl alcohol can control the particle size distribution of the resin white spheres, avoiding excessively large or small particle sizes that would affect the performance of the final product.

[0014] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white spheres, the mass ratio of the oil phase to the water phase in step (2) is 1:(2.5~8). An appropriate ratio can ensure that the oil phase is uniformly dispersed in the water phase, forming droplets of uniform size, thus ensuring the uniformity of the polymerization reaction; a suitable ratio helps to control the reaction temperature and reaction time, thereby improving reaction efficiency and product quality.

[0015] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white spheres, in step (2), the reaction time is 10-14 hours. An appropriate reaction time can ensure that the monomers are fully polymerized to form high-molecular-weight resin white spheres, thereby improving the mechanical strength and chemical stability of the product; controlling the reaction time can avoid excessive crosslinking and increased brittleness caused by over-polymerization.

[0016] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white balls, step (3) includes: The good solvent is at least one selected from 1,2-dichloroethane, ethyl acetate, dichloromethane, tetrahydrofuran, and 1,4-dioxane; The unsuitable solvent is at least one of water, methanol, ethanol, and N,N-dimethylformamide.

[0017] Alternating between good and bad solvents can effectively utilize the "crowding-out effect" of swelling and contraction to deeply remove impurities such as oligomers from the polymer network and improve the purity of resin white spheres. Good solvents can dissolve oligomers and linear polymers, while bad solvents promote the precipitation of these impurities, thereby achieving efficient purification.

[0018] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white balls, in step (3), the volume ratio of the resin white balls to the good solvent or the poor solvent is 1:(3~10). That is, when the resin white balls are soaked in the good solvent, the volume ratio of the resin white balls to the good solvent is 1:(3~10); when the resin white balls are soaked in the poor solvent, the volume ratio of the resin white balls to the poor solvent is 1:(3~10). An appropriate volume ratio can ensure that the resin white balls are fully soaked in the solvent, thereby improving the dissolution and precipitation efficiency of impurities; a reasonable volume ratio can avoid solvent waste and control production costs.

[0019] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white balls, step (3) includes: The soaking temperature is 30~90℃, and the soaking time is 2~6 hours each time; The number of times to soak alternately is 2 to 4.

[0020] Appropriate temperature and time can optimize the dissolution and precipitation of solvents and improve the removal efficiency of impurities; suitable temperature and time can avoid solvent evaporation and thermal degradation of resin white balls, ensuring product quality.

[0021] As a preferred embodiment, in the above-mentioned method for preparing high-purity resin white balls, the drying temperature in step (3) is 100~105℃. An appropriate drying temperature can ensure that the resin white balls are completely dried, avoiding residual solvent from affecting product performance; a suitable drying temperature can prevent thermal degradation of the resin white balls and maintain their mechanical strength and chemical stability.

[0022] By implementing the above-mentioned preferred scheme, the purity and performance of high-purity resin white balls can be further improved, meeting the high requirements of high-performance functional resins for matrix materials.

[0023] A second aspect of the present invention provides a high-purity resin white sphere prepared by the above-described preparation method. The high-purity resin white sphere releases less than 1 mg / L of total organic carbon after being soaked in water for 48 h.

[0024] A third aspect of the present invention provides the application of the above-described high-purity resin white spheres in the preparation of ion exchange resins.

[0025] Compared with the prior art, the present invention has the following significant advantages: High purification efficiency and good safety: The raw material is purified by room temperature adsorption column method, avoiding the thermal self-polymerization problem that may be caused by vacuum distillation. The operation is safe and the raw material loss is low. Thorough impurity removal: The innovative use of the "crowding-out effect" of cross-linked polymer network swelling in good solvents and shrinking in poor solvents can effectively extract and remove impurities such as oligomers and linear polymers wrapped inside the network, achieving a deep purification effect that is difficult to achieve by traditional cleaning methods. Extremely high product purity: The high-purity resin white balls prepared by the method of this invention have significantly improved purity indicators. The data from the examples show that the total organic carbon (TOC) release of the product after soaking in water for 48 hours is consistently below 1 mg / L (i.e., 1 ppm), which is far lower than that of commercial white spheres (approximately 30.7 ppm). The downstream products exhibit excellent performance: the ion exchange resin prepared using this high-purity white sphere as a matrix has key performance parameters, such as mass exchange capacity (up to 4.65 mmol / g or higher), crushing strength (up to 8.1 N / sphere or higher), and sphericity after grinding (up to 92% or higher), which are all superior to those of commercial 001×7 type resin, demonstrating excellent application performance.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0027] Figure 1 Infrared characterization of the high-purity resin white spheres prepared in Examples 1-4. Detailed Implementation

[0028] The following description provides numerous specific details to offer a more thorough understanding of the technical solutions provided by this invention. However, it will be apparent to those skilled in the art that the technical solutions provided by this invention can be implemented without one or more of these details.

[0029] In the embodiments and comparative examples of this invention, the raw materials are commercially available.

[0030] Example 1 (1) Commercial styrene and divinylbenzene were purified by passing them through an adsorption column packed with alkaline alumina; (2) Take 96 g of purified styrene and 4 g of divinylbenzene, add 0.5 g of initiator benzoyl peroxide, mix evenly to obtain an oil phase, add the oil phase to 300 mL of an aqueous solution containing 0.1% polyvinyl alcohol, stir to form uniformly sized droplets, then slowly raise the temperature and react at 80℃ for 12 hours. After the reaction is completed, lower to room temperature to obtain resin white balls. (3) Take 20 mL of resin white balls in an Erlenmeyer flask, add 100 mL of dichloroethane, soak at 40°C for 2 h, filter out the dichloroethane, then add 100 mL of methanol, soak at 40°C for 2 h, after the methanol soaking is finished, continue to soak with dichloroethane and methanol alternately twice, and dry at 100°C to obtain high-purity resin white balls.

[0031] Example 2 (1) Commercial styrene and divinylbenzene were purified by passing them through an adsorption column packed with alkaline alumina; (2) Take 93 g of purified styrene and 7 g of divinylbenzene, add 0.5 g of initiator azobisisobutyronitrile, mix evenly to obtain an oil phase, add the oil phase to 300 mL of an aqueous solution containing 0.1% polyvinyl alcohol, stir to form uniformly sized droplets, then slowly raise the temperature and react at 80℃ for 12 hours. After the reaction is completed, lower to room temperature to obtain resin white balls. (3) Take 20 mL of resin white balls in an Erlenmeyer flask, add 80 mL of dichloroethane, soak at 40°C for 4 h, filter out the dichloroethane, then add 80 mL of ethanol, soak at 50°C for 4 h, after the ethanol soaking is finished, continue to soak with dichloroethane and ethanol alternately twice, and dry at 100°C to obtain high-purity white balls.

[0032] Example 3 (1) Commercial styrene and divinylbenzene were purified by passing them through an adsorption column packed with alkaline alumina; (2) Take 93 g of purified styrene and 7 g of divinylbenzene, add 1 g of initiator benzoyl peroxide, mix evenly to obtain an oil phase, add the oil phase to 300 mL of an aqueous solution containing 2% polyvinyl alcohol, stir to form uniformly sized droplets, then slowly raise the temperature and react at 80℃ for 12 hours. After the reaction is completed, lower to room temperature to obtain resin white balls. (3) Take 20 mL of resin white balls in an Erlenmeyer flask, add 120 mL of dichloroethane, soak at 40°C for 4 h, filter out the dichloroethane, then add 120 mL of ethanol, soak at 50°C for 4 h, after the ethanol soaking is finished, continue to soak with dichloroethane and ethanol alternately twice, and dry at 100°C to obtain high-purity white balls.

[0033] Example 4 (1) Commercial styrene and divinylbenzene were purified by passing them through an adsorption column packed with alkaline alumina; (2) Take 90 g of purified styrene and 10 g of divinylbenzene, add 1 g of initiator azobisisobutyronitrile, mix evenly to obtain an oil phase, add the oil phase to 500 mL of an aqueous solution containing 2% polyvinyl alcohol, stir to form uniformly sized droplets, then slowly raise the temperature and react at 85℃ for 12 hours. After the reaction is completed, lower to room temperature to obtain resin white balls. (3) Take 20 mL of resin white balls in an Erlenmeyer flask, add 100 mL of tetrahydrofuran, soak at 40°C for 4 h, filter out the tetrahydrofuran, then add 100 mL of methanol, soak at 40°C for 4 h, after the methanol soaking is finished, continue to soak with tetrahydrofuran and methanol alternately 4 times, and dry at 100°C to obtain high-purity white balls.

[0034] Comparative Example 1 Commercial 001×7 resin.

[0035] Take 50 mL of the high-purity white spheres prepared in Examples 1-4, add them to 100 mL of pure water, and soak them at 50°C for 48 h. Analyze the total organic carbon (TOC) of the soaking solution, and use commercial white spheres as comparative example 1. The results are shown in Table 1: Table 1. TOC content and particle size data of Examples 1-4 and commercial high-purity resin white balls.

[0036] Note: TOC test of resin: Refer to the standard method for determination of organic leachate of ion exchange resin DL / T 1077-2018.

[0037] As can be clearly seen from the table, the TOC of the high-purity resin white balls obtained using Examples 1-4 is significantly lower than that of commercial white balls, indicating that this method can be used to prepare high-purity resin white balls.

[0038] The high-purity white spheres prepared using the examples were reacted with concentrated sulfuric acid under swelling conditions in dichloroethane to incorporate functional groups. The performance indicators of the prepared cation exchange resins were compared with those of the commercial 001×7 resin, as shown in Table 2 below: Table 2 Comparison of performance indicators between the examples and commercial 001×7 resin

[0039] As can be seen from the table above, the cation exchange resin obtained by sulfonation reaction using the high-purity white spheres obtained in this application as the matrix has high exchange capacity, crushing strength and sphericity after grinding. Therefore, this method can be applied to prepare matrix white spheres for high-performance functional resins.

[0040] Infrared spectral characterization: The high-purity resin white spheres prepared in Examples 1-4 were subjected to infrared spectral analysis using a Tensor II infrared spectrometer manufactured by Bruker GmbH, Germany. The wavenumber range was 4000-400 cm⁻¹. -1 After drying the material, it can be tested without tableting. The spectral results are as follows: Figure 1 As shown.

[0041] Figure 1 The infrared characterization of the high-purity resin white spheres prepared in Examples 1-4 is shown. Figure 1 In the graph, the horizontal axis represents wavelength, and the vertical axis represents intensity. For example... Figure 1 As shown, the spectral curves of all samples highly overlap, all falling within the range of 1600-1610 cm⁻¹. -1 (C=C stretching vibration of benzene ring), 697 cm -1 and 755 cm -1 (Out-of-plane bending vibration of monosubstituted benzene CH), 3030 cm -1 (CH stretching vibration on the benzene ring) and 2920-2850 cm⁻¹ -1 Typical cross-linked polystyrene characteristic absorption peaks were observed at locations such as (aliphatic CH stretching vibration). This indicates that the purification process of the present invention effectively removes impurities while completely preserving the polymer backbone structure of the high-purity resin white spheres, ensuring that its basic physicochemical properties as a functional resin matrix remain unaffected.

[0042] Comparative Example 2 The only difference from Example 1 is that step (2) is performed at 72°C. The reaction temperature is low, the monomer polymerization is insufficient, and the cross-linking degree of the prepared polymer is insufficient. On the one hand, the impurity content of the white spheres is high, with a TOC of 4 ppm. On the other hand, the crushing strength of the prepared anion resin is only 5 N / sphere.

[0043] Comparative Example 3 The only difference from Example 1 is that step (2) is reacted at 90°C. The higher reaction temperature will cause local overheating, uneven polymerization, and an increase in physical crosslinking points, making it difficult for the linear polymer to be discharged during purification in step (3). The TOC is 3 ppm, and the final anion exchange capacity is low, only 4 mmol / g.

[0044] Comparative Example 4 The only difference from Example 2 is that in step (1), instead of using an adsorption column packed with alkaline alumina for raw material purification, an organic ion exchange resin column was used. The resulting white spheres had a TOC of 2 ppm. This is because the raw materials styrene and divinylbenzene are organic compounds. Using an organic ion exchange resin column for raw material purification increases both the risk of resin filler poisoning and the leaching of organic impurities from the resin filler.

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity resin white spheres, characterized in that, The preparation method includes: (1) Styrene and divinylbenzene are purified by passing them through an adsorption column packed with alkaline alumina; (2) The raw material purified in step (1) is mixed with the initiator to obtain an oil phase. The oil phase is added to the aqueous phase containing polyvinyl alcohol. After stirring to form uniformly sized droplets, the temperature is slowly increased and reacted at 75~85℃ to obtain resin white balls. (3) After repeatedly soaking the resin white balls prepared in step (2) in good solvent and bad solvent, dry them to obtain high-purity resin white balls.

2. The method for preparing high-purity resin white spheres according to claim 1, characterized in that, Step (2) satisfies at least one of the following characteristics: The contents of each component in the oil phase, by mass percentage, are: initiator 0.4%~1.5%, styrene 89%~95.6%, and diethylene 3.9%~10%; The initiator is azobisisobutyronitrile or benzoyl peroxide; The mass fraction of polyvinyl alcohol in the aqueous phase is 0.1%~4%; The mass ratio of oil phase to water phase is 1:(2.5~8).

3. The method for preparing high-purity resin white spheres according to claim 1, characterized in that, In step (2), the reaction time is 10 to 14 hours.

4. The method for preparing high-purity resin white spheres according to claim 1, characterized in that, In step (3): The good solvent is at least one selected from 1,2-dichloroethane, ethyl acetate, dichloromethane, tetrahydrofuran, and 1,4-dioxane; The unsuitable solvent is at least one of water, methanol, ethanol, and N,N-dimethylformamide.

5. The method for preparing high-purity resin white spheres according to claim 1, characterized in that, In step (3), the volume ratio of resin white balls to good solvent or bad solvent is 1:(3~10).

6. The method for preparing high-purity resin white spheres according to claim 1, characterized in that, In step (3): The soaking temperature is 30~90℃, and the soaking time is 2~6 hours each time; The number of times to soak alternately is 2 to 4.

7. The method for preparing high-purity resin white spheres according to claim 1, characterized in that, In step (3), the drying temperature is 100~105℃.

8. A high-purity resin white ball, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

9. The high-purity resin white ball according to claim 8, characterized in that, The total organic carbon released by the high-purity resin white balls after soaking in water for 48 hours is less than 1 mg / L.

10. The application of the high-purity resin white spheres according to claim 8 in the preparation of ion exchange resins.

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