A method for purifying ultraviolet absorber uv-3030
By using carbon disulfide treatment and low-temperature negative pressure drying technology, the problem of low melting point caused by solvent residue in the production of UV-3030 was solved, achieving efficient and low-cost product purification, simplifying the production process and reducing environmental pollution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN UNIV OF SCI & TECH
- Filing Date
- 2023-09-15
- Publication Date
- 2026-06-02
AI Technical Summary
In the existing UV-3030 production process, solvent residue leads to a low product melting point, making it difficult to meet standards. Furthermore, the high-temperature solvent removal process is complex, energy-intensive, and has high production costs.
The recrystallized product is treated with carbon disulfide by suspending it in carbon disulfide and heating it under reflux. The compatibility between carbon disulfide and the solvent replaces solvent molecules. The product is then dried using a low-temperature negative pressure vacuum centrifuge to recover carbon disulfide and reduce environmental pollution.
This resulted in high-yield, high-purity UV-3030 products, reducing production costs, solvent loss, and environmental pollution, and simplifying the process.
Abstract
Description
Technical Field
[0001] This invention relates to a refining method for ultraviolet absorber UV-3030, belonging to the field of fine chemicals and polymer material additives. Background Technology
[0002] The industrial production of UV-3030 typically involves recrystallization from organic solvents or mixtures such as toluene, xylene, tetrachloroethylene, dichloromethane, trichloromethane, dichloroethane, ethyl acetate, methanol, and ethanol. Under current processes, the product's melting point after ordinary drying is only around 130-140℃, failing to meet the product standard's requirement of 172-175℃. This is because the benzene rings and polar groups in the UV-3030 molecular structure readily generate strong intermolecular forces with polar or aromatic solvent molecules like toluene, ethyl acetate, methanol, and ethanol. When UV-3030 crystallizes at lower temperatures, these solvent molecules enter the crystal lattice as molecular adducts, becoming part of the crystal. These solvent molecules, similar to water of crystallization in inorganic salts, are difficult to remove with simple drying. Their presence lowers the melting point of UV-3030, causing the product to fail to meet the technical specifications stipulated in the enterprise standard.
[0003] To solve this problem, the product needs to be heated to above its melting point, allowing it to be thoroughly dried in a molten state to remove the solvent. After this high-temperature solvent removal process, no solvent molecules are involved in the crystallization, thus achieving the required melting point. However, this process is complex, increases production costs, and has two significant drawbacks: first, the energy consumption of melting the product at high temperatures followed by drying is far greater than that of ordinary drying processes; second, a high-temperature melt granulator is required to obtain a marketable product. Clearly, this is a complex, energy-intensive, and lengthy production process.
[0004] The purpose of this invention is to solve the problem of removing residual organic solvents in the product after recrystallization of organic solvents, and to simplify the production process of UV-3030. Summary of the Invention
[0005] To address the significant shortcomings of existing processes, this invention employs the nonpolar inorganic compound carbon disulfide to treat recrystallized products. The principle is based on the excellent compatibility of carbon disulfide with organic solvents and its non-formation of molecular adducts with the ultraviolet absorber UV-3030. The solvent-containing product obtained from recrystallization is suspended in carbon disulfide and heated under reflux. Carbon disulfide molecules replace organic solvent molecules in the crystals, allowing these molecules to enter the carbon disulfide solution. Since the intermolecular forces between carbon disulfide molecules and UV-3030 are much weaker than those of the organic solvent, they cannot form molecular adducts with UV-3030 and can therefore be removed using a simple drying process.
[0006] In practice, due to the low boiling point of carbon disulfide, the drying process is carried out in a vacuum centrifuge under negative pressure at less than 30°C. The dried gas is condensed through a heat exchanger to recover carbon disulfide. This low-temperature negative pressure operation not only ensures the recovery rate of carbon disulfide but also reduces environmental pollution caused by carbon disulfide emissions. In addition, the lower drying temperature also results in better product quality and good energy-saving effects.
[0007] The refined product of this invention is then refluxed in carbon disulfide to obtain a high-purity product with a melting point that meets the requirements in high yield.
[0008] Beneficial effects
[0009] 1. Products crystallized in a composite solvent of tetrachloroethylene and ethyl acetate by reflux treatment with carbon disulfide can be dried at low temperature to obtain high-purity products with the required melting point, which greatly reduces the process cost of the product.
[0010] 2. The combined use of low-temperature negative pressure drying process and cryogenic solvent recovery technology can reduce solvent loss and reduce environmental pollution caused by carbon disulfide volatilization. Detailed Implementation
[0011] The following embodiments describe the specific implementation process of the technical solution of the present invention, but the technical solution of the present invention is not limited to the specific embodiments listed below, and also includes any combination of the specific embodiments.
[0012] Example 1. 30g of the pre-refined UV-3030 product obtained by recrystallization from toluene was suspended in 45ml of carbon disulfide and refluxed for 30min. After cooling and filtration to remove the solvent, the product was transferred to a vacuum centrifuge. A vacuum of 10-20kPa was applied at room temperature, and the drying gas was passed through a cryogenic heat exchanger to recover the carbon disulfide. The drying time was approximately 30min. 28.9g of the refined UV-3030 product was obtained, with a drying yield of 96.3% and a melting point of 174.3-175.8℃.
[0013] Example 2. Following the same feeding amount and operation process as in Example 1, except that the amount of carbon disulfide was changed to 15 ml, after drying, 29.0 g of refined UV-3030 product was obtained, with a drying yield of 96.7% and a melting point of 168.3-170.2℃.
[0014] Example 3. Following the same feeding amount and operation process as in Example 1, except that the amount of carbon disulfide was changed to 30 ml, after drying, 29.0 g of refined UV-3030 product was obtained, with a drying yield of 96.7% and a melting point of 170.3-174.2℃.
[0015] Example 4. Following the same feeding amount and operation process as in Example 1, except that the amount of carbon disulfide was changed to 60 ml, after drying, 28.7 g of refined UV-3030 product was obtained, with a drying yield of 95.7% and a melting point of 174.5-175.8 °C.
[0016] Example 5. Following the same feeding amount and operation process as in Example 1, except that the carbon disulfide reflux time was changed to 20 min, 28.9 g of refined UV-3030 product was obtained after drying, with a drying yield of 96.3% and a melting point of 173.5-175.3℃.
[0017] Example 6. Following the same feeding amount and operation process as in Example 1, except that the carbon disulfide reflux time was changed to 45 min, 28.9 g of refined UV-3030 product was obtained after drying, with a drying yield of 96.3% and a melting point of 174.4-175.5℃.
[0018] Example 7. Following the same feeding amount and operation process as in Example 1, except that the carbon disulfide reflux time was changed to 60 min, 28.7 g of refined UV-3030 product was obtained after drying, with a drying yield of 95.7% and a melting point of 174.4-175.5℃.
Claims
1. A refining method of ultraviolet absorber UV-3030, characterized by, The refining method of the ultraviolet absorber UV-3030 is realized by the following method: the crude product UV-3030 is suspended in carbon disulfide solution, heated to reflux, filtered, and dried to obtain a refined product with a melting point of 174-176℃, and the refining yield is greater than 95%; The carbon disulfide solvent input is 0.5-2 times the product; The heating reflux time is 20-60 min; The drying is carried out in a vacuum centrifugal dryer below 30℃, and the drying gas passes through a heat exchanger with dry ice / ethanol cryogenic medium to recover carbon disulfide, and the dry ice / ethanol cryogenic medium temperature is-45-50℃.
2. The method of purifying ultraviolet absorber UV-3030 according to claim 1, characterized by, The crude product UV-3030 is a preliminary refined product obtained by recrystallization with at least one of toluene, xylene, tetrachloroethylene, dichloromethane, trichloromethane, dichloroethane, ethyl acetate, methanol, and ethanol.