A method for producing antioxidant 1076 by recycling mother liquor using antioxidant 1076

Abstract

The application discloses a method for preparing antioxidant 1076 by recycling mother liquor by using antioxidant 1076, and comprises the following steps: after the mother liquor is treated, the mother liquor is placed in a first vacuum distillation device, methanol is collected, and the remaining material is a still residue; the still residue is transferred to a second vacuum distillation device, and a mixed fraction is separated out; quantitative analysis is carried out, the amount of fresh 3,5-methyl ester and fresh octadecanol which need to be added is calculated according to the molar ratio of octadecanol to 3,5-methyl ester being 1:1.02-1:1.05; the mixed fraction, the added raw materials and a catalyst are put into a reaction kettle; antioxidant 1076 products are obtained through an ester exchange reaction and a post-treatment process, and the mother liquor generated in the process is returned to step 1 and enters the next circulation process. The application effectively avoids waste of raw materials, reduces production cost and avoids environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of polymer material additives synthesis technology, specifically to a method for preparing antioxidant 1076 by recycling the mother liquor produced by antioxidant 1076. Background Technology

[0002] Antioxidant β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, commonly known as antioxidant 1076, is a commonly used, highly efficient hindered phenolic antioxidant widely applied in polymer materials such as polyethylene, polypropylene, and ABS resin. Its mainstream synthesis method is a two-step process. The first step involves a Michael addition reaction between 2,6-di-tert-butylphenol (2,6-phenol) and methyl acrylate to obtain methyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (3,5-methyl ester). The second step involves transesterification of 3,5-methyl ester under alkaline catalysis, followed by crystallization, centrifugation, and drying to obtain the final product, antioxidant 1076.

[0003] In actual industrial production, to ensure the reaction is as complete as possible, one of the raw materials is usually added in appropriate excess. After the reaction is complete, the product is obtained through crystallization and filtration, and the remaining liquid is the mother liquor. This mother liquor has a complex composition, containing solvents (such as methanol), catalyst residues, and unreacted 3,5-methyl ester and octadecyl alcohol. Currently, this part of the mother liquor is mostly treated as waste liquid, which not only wastes valuable raw materials and increases production costs, but also puts pressure on environmental treatment.

[0004] Therefore, developing a clean production method that can effectively recycle unreacted raw materials from mother liquor, achieving resource recycling, cost reduction, and emission reduction, has significant industrial application value. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a method for preparing antioxidant 1076 using recycled mother liquor. This method achieves efficient recycling of raw materials through targeted separation and precise reuse of the mother liquor, significantly reducing raw material consumption and production costs, while also minimizing emissions of waste.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing antioxidant 1076 using recycled mother liquor from antioxidant 1076 production includes the following steps: ① Mother liquor treatment process: Collect the mother liquor produced after the synthesis reaction of antioxidant 1076 through crystallization and filtration processes, and filter the mother liquor; ② First vacuum distillation: Place the filtered mother liquor in the first vacuum distillation apparatus, collect the distilled methanol, and the remaining material is the residue; ③ Second vacuum distillation: The residue obtained in step ② is transferred to the second vacuum distillation apparatus to separate the mixed fraction containing unreacted 3,5-methyl ester and octadecyl alcohol; ④ Component measurement: Quantitative analysis was performed on the mixed fraction to determine the contents of 3,5-methyl ester and octadecyl alcohol, respectively; ⑤ Ingredients and replenishment: Based on the measurement results in step ④, calculate the amount of fresh 3,5-methyl ester and fresh octadecyl alcohol to be replenished according to the molar ratio of octadecyl alcohol to 3,5-methyl ester of 1:1.02 to 1:1.05; add the mixed fraction, the replenished fresh 3,5-methyl ester, the fresh octadecyl alcohol and the catalyst into the reaction vessel in proportion. ⑥ Transesterification reaction: Transesterification reaction was carried out at a reaction temperature of 175~185℃ and a pressure of -0.09MPa~-0.1MPa. After a reaction time of 4~5 hours, crude antioxidant 1076 was generated. ⑦ Post-processing: The crude antioxidant 1076 is subjected to hot melting, crystallization and filtration processes to obtain a recovered mother liquor and a solid. The solid is washed and dried to obtain the antioxidant 1076 product. The recovered mother liquor is returned to step ① to enter the next cycle process.

[0007] Preferably, the temperature of the first vacuum distillation is 40℃~65℃ and the pressure is -0.08MPa to -0.095MPa.

[0008] Preferably, the temperature of the second vacuum distillation is 120℃-205℃, and the pressure is -0.095MPa to -0.099MPa.

[0009] Preferably, the catalyst is zinc acetate dihydrate, dibutyltin dilaurate, or tetraisopropyl titanate, and the amount of catalyst added is 0.1% to 0.5% of the total mass of 3,5-methyl ester. In this invention, the total mass of 3,5-methyl ester is the sum of the mass of 3,5-methyl ester in the mixed fraction and the mass of freshly added 3,5-methyl ester.

[0010] Preferably, in step ⑦, the solvent for hot melting is methanol, the hot melting temperature is 60℃~70℃, and the amount of hot melting solvent added is 2.5~3.5 times the crude weight of antioxidant 1076; the crystallization temperature is 40℃~42℃, and the crystallization time is 1~2 hours; the solvent for washing is methanol; the drying temperature is 40~45℃, and the drying time is 2~3 hours.

[0011] Preferably, the second vacuum distillation employs a segmented collection method, first collecting the octadecyl alcohol enriched fraction at a lower temperature, and then collecting the 3,5-methyl ester enriched fraction at a higher temperature, allowing for more flexible adjustment of subsequent feed ingredients. The reactor pressure is controlled at -0.098 MPa, with the octadecyl alcohol enriched fraction first collected at 140~160℃, and the 3,5-methyl ester enriched fraction collected at 160~205℃.

[0012] Beneficial effects of this invention: 1. Through precise vacuum distillation, methanol, unreacted 3,5-methyl ester and octadecyl alcohol in the mother liquor are effectively separated and recovered, and can be directly reused as raw materials or solvents in the production process, which greatly improves the total utilization rate of raw materials (up to more than 95%) and reduces material consumption from the source.

[0013] 2. It directly saves the expensive raw materials (3,5-methyl ester and octadecyl alcohol) that would otherwise be discarded with the mother liquor, while the recovered methanol replaces the fresh solvent, reducing production costs.

[0014] 3. It greatly reduces the amount of high-COD organic waste liquid generated and the difficulty of treatment, realizing the concept of clean production and green chemistry, and has significant environmental benefits. Detailed Implementation

[0015] To make the technical problems solved by the present invention, the technical solutions and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0016] Example 1

[0017] (a) Single-batch mother liquor recovery and utilization

[0018] ① Mother liquor treatment process: Take 1000g of mother liquor produced after the synthesis reaction of antioxidant 1076 and crystallization and filtration process. It comes from the previous batch of conventional production. The purpose of filtration is to remove the small amount of solid impurities entrained in it. ② First vacuum distillation: conditions were 55℃ / -0.09 MPa, yielding 935g of methanol, with the remaining material being the still residue. Gas chromatography analysis showed that the purity of the distilled methanol was >99.5%. The purpose of this step was to recover the methanol solvent. The resulting methanol had high purity and could be directly used as a washing solvent in subsequent post-processing, achieving effective utilization. ③ Second vacuum distillation: Transfer the residue obtained in step ② to the second vacuum distillation apparatus, control the pressure of the reactor to -0.098MPa, collect the main fraction between 140-205℃, and obtain 42g of mixed fraction; ④ Component quantification: The mixed fraction was quantitatively analyzed to determine the contents of 3,5-methyl ester and octadecyl alcohol. The mixed fraction contained 60% 3,5-methyl ester (by weight), 35% octadecyl alcohol, and the remainder consisted of small amounts of other components (mainly small amounts of 1076 and some impurities). Based on this, the effective raw materials recovered were calculated to be: 25.2 g of 3,5-methyl ester and 14.7 g of octadecyl alcohol. ⑤ Batching and Replenishment: The planned total feed includes 80g of octadecyl alcohol and 90.80g of 3,5-methyl ester (molar ratio of octadecyl alcohol to 3,5-methyl ester 1:1.05). Therefore, 65.6g of fresh 3,5-methyl ester and 65.3g of fresh octadecyl alcohol need to be added. Add the entire mixed fraction (42g), the added 65.6g of 3,5-methyl ester, 65.3g of octadecyl alcohol, and the catalyst zinc acetate dihydrate to the reactor. The addition amount is 0.1% of the total mass of 3,5-methyl ester. ⑥ Transesterification reaction: The temperature was raised to 180±2℃ under stirring, and the system pressure was maintained at -0.096 MPa for 4 hours. The methanol generated during the reaction was carried away by the negative pressure to generate crude antioxidant 1076. ⑦ Post-processing: Transfer the crude antioxidant 1076 to a crystallization vessel, and heat-melt it with the methanol recovered in step ② at a temperature of 60°C. The solvent for heat melting is methanol, and the amount of methanol added is 3 times the mass of the crude 1076. Crystallize (using the recovered methanol), filter to obtain a solid, wash the solid, and vacuum dry it at 40°C for 2 hours to obtain 152g of white flocculent antioxidant 1076 product.

[0019] (II) Analysis

[0020] This production process processed approximately 1000g of mother liquor, achieving solvent and raw material recycling and reducing the discharge of high-COD organic waste liquid by approximately 935g.

[0021] The GC product has a purity of 99.83%, a melting point of 51.5~52.0℃, a light transmittance of 98.6% at 425nm and 99.4% at 500nm, and a heating loss of 0.13%, which meets the industry standard (GB / T 3795-2022).

[0022] This time, the savings in fresh 3,5-methyl ester were 25.2 / 90.8 = 27.75%, and the savings in fresh octadecyl alcohol were 14.7 / 80 = 18.38%.

[0023] (iii) Continuous batch cyclical verification

[0024] This embodiment was conducted on a simulated continuous production line, where the mother liquor generated after the synthesis reaction of the previous batch was used as the starting material for the next batch, and this process was repeated for a total of 5 consecutive cycles. Key material data were rigorously recorded for each cycle, and the final product underwent comprehensive quality testing to assess the stability of the cyclical process.

[0025] Starting mother liquor: The standard mother liquor obtained after the first use of traditional process (all fresh raw materials) is designated as batch 0 mother liquor, and its main composition is the same as that of the mother liquor in Example 1.

[0026] The target amount of mother liquor processed per batch is 1000g (the actual input may vary slightly depending on the output of the previous batch).

[0027] Recovery process: Follow steps ① to ⑦ above. Target single batch fresh raw material baseline feed amount: 170.3 g of 3,5-methyl ester and 150.0 g of octadecyl alcohol.

[0028] Analytical methods: methanol content (GC), raw material composition (GC), product purity (GC), melting point (capillary method), transmittance (UV-Vis spectrophotometer).

[0029] ; (iv) Data analysis and conclusions. In terms of process stability, the material balance is stable and the reaction yield is stable. Stable material balance: The small fluctuation range of the amount of mother liquor processed in each batch, the amount of recovered methanol and the weight of the raw material mixture proves that the separation and recovery process has excellent reproducibility. The reaction yield was stable: the product yield remained between 260 and 280 g, and the yield of each batch was within the range of 90.12% to 94.86%, without significant decline, indicating that the reaction process was stable and controllable. Regarding the cumulative effect of material circulation, impurities accumulate slowly, and the core indicators meet the standards. Impurities accumulate slowly: As shown in Table 1, the "Other" component in the recovered mixed fraction gradually increases from 5.5% in cycle 1 to 9.5% in cycle 5. This is in line with the expected normal phenomenon of material circulation. Key indicators met: Despite some accumulation of impurities, all five cycles of production of antioxidant 1076 products had a purity (GC) higher than 98.5%, melting points that fell entirely within the qualified product standard range (50-55℃), and transmittance at 425nm and 500nm that were ≥98% / 99%, meeting national standards and the requirements of mainstream customers. Summary of economic and environmental benefits (total over 5 cycles): The cumulative savings in fresh 3,5-methyl ester is: (170.3×5) - (30.7+27.5+29.0+31.0+32.5) = 851.5–150.7 = 700.8 g, with a savings rate of 17.70%. The cumulative amount of fresh octadecyl alcohol saved is: (150×5) - (19.3+17.4+18.4+19.3+20.0) =750–94.4= 655.6g, with a saving rate of 12.59%. A total of 4670g of methanol was recycled, achieving an internal closed loop for the solvent. This example, through real-world data from five consecutive batches, fully demonstrates that the mother liquor recovery and utilization method described in this invention possesses excellent process stability and long-term operational reliability. Even with the predictable and slow accumulation of impurities, the core of this process—"precise separation, quantitative analysis, and on-demand replenishment"—can continuously and stably produce qualified products, while achieving a core raw material saving rate of over 10% and significant wastewater reduction, fully realizing the invention's objectives of resource recycling, cost reduction and efficiency improvement, and green production. Example 2 ① Mother liquor treatment process: Take 1000g of mother liquor produced after the synthesis reaction of antioxidant 1076, which is obtained through crystallization and filtration processes. It comes from the previous batch of conventional production and is filtered. ② First vacuum distillation: conditions were 40℃ / -0.08MPa, yielding 963g of methanol, with the remaining material being the still residue. Gas chromatography analysis showed that the purity of the distilled methanol was >99.5%. The purpose of this step was to recover the methanol solvent. The resulting methanol had high purity and could be directly used as a washing solvent in subsequent post-processing, achieving effective utilization. ③ Second vacuum distillation: Transfer the residue obtained in step ② to the second vacuum distillation apparatus, control the pressure of the reactor to -0.099MPa, collect the mixed fraction between 120℃ and 205℃, and obtain 28g of mixed fraction; ④ Component quantification: The mixed fraction was quantitatively analyzed to determine the contents of 3,5-methyl ester and octadecyl alcohol. The mixed fraction contained 52.5% 3,5-methyl ester (by weight), 36.2% octadecyl alcohol, and the remainder consisted of small amounts of other components (mainly small amounts of 1076 and some impurities). Based on this, the effective raw materials recovered were calculated to be: 14.7 g of 3,5-methyl ester and 10.14 g of octadecyl alcohol. ⑤ Batching and Replenishment: The planned total feed includes 150.0g of octadecyl alcohol and 165.39g of 3,5-methyl ester (molar ratio of octadecyl alcohol to 3,5-methyl ester is 1:1.02). Therefore, 150.69g of fresh 3,5-methyl ester and 139.86g of fresh octadecyl alcohol need to be added. Add the entire mixed fraction (28g), the added 150.69g of 3,5-methyl ester, and 139.86g of octadecyl alcohol, along with the catalyst dibutyltin dilaurate, to the reactor in proportion to 0.5% of the total mass of 3,5-methyl ester. ⑥ Transesterification reaction: The temperature was raised to 183±2℃ under stirring, and the system pressure was maintained at -0.09 MPa for 4 hours. The methanol generated during the reaction was carried away by the negative pressure to generate crude antioxidant 1076. ⑦ Post-processing: Transfer the crude antioxidant 1076 to a crystallization kettle, and perform hot melting with the methanol recovered in step ②. The hot melting temperature is 70℃, the hot melting solvent is methanol, and the amount of methanol added is 2.5 times the mass of crude 1076. Crystallize (using the recovered methanol) at a temperature of 40℃ for 2 hours. After filtration, obtain the solid and the recovered mother liquor. Wash the solid and vacuum dry it at 45℃ for 3 hours to obtain the white flocculent antioxidant 1076 product. The mother liquor is returned to step ① to begin the next cycle. The GC-processed product has a purity of 99.39%, a melting point of 51.0~52.0℃, light transmittance of 98.4% at 425nm and 99.0% at 500nm, and a heating loss of 0.07%, which meets the industry standard (GB / T 3795-2022). This time, the savings in fresh 3,5-methyl ester were 14.7 / 165.39 = 8.8%, and the savings in fresh octadecyl alcohol were 10.14 / 150.0 = 6.76%. Example 3 ① Mother liquor treatment process: Take 1000g of mother liquor produced after the synthesis reaction of antioxidant 1076, which is obtained through crystallization and filtration processes. It comes from the previous batch of conventional production and is filtered. ② First vacuum distillation: conditions were 65℃ / -0.095MPa, yielding 955g of methanol, with the remaining material being the still residue. Gas chromatography analysis showed that the purity of the distilled methanol was >99.5%. The purpose of this step was to recover the methanol solvent. The resulting methanol had high purity and could be directly used as a washing solvent in subsequent post-processing, achieving effective utilization. ③ Second vacuum distillation: Transfer the residue obtained in step ② to the second vacuum distillation apparatus, control the pressure of the reactor to -0.095MPa, collect the mixed fraction between 120℃ and 205℃, and obtain 39g of mixed fraction; ④ Component quantification: The mixed fraction was quantitatively analyzed to determine the contents of 3,5-methyl ester and octadecyl alcohol. The mixed fraction contained 56.8% 3,5-methyl ester (by weight), 27.6% octadecyl alcohol, and the remainder consisted of small amounts of other components (mainly small amounts of 1076 and some impurities). Based on this, the effective raw materials recovered were: 22.15 g of 3,5-methyl ester and 10.76 g of octadecyl alcohol. ⑤ Batching and Replenishment: The planned total feed includes 150.0g of octadecyl alcohol and 170.3g of 3,5-methyl ester (molar ratio of octadecyl alcohol to 3,5-methyl ester 1:1.05). Therefore, 148.15g of fresh 3,5-methyl ester and 139.76g of fresh octadecyl alcohol need to be added. Add the entire mixed fraction (39g), the added 148.15g of 3,5-methyl ester, 139.76g of octadecyl alcohol, and the catalyst tetraisopropyl titanate to the reactor in the specified proportions; the catalyst addition amount is 0.3% of the total mass of 3,5-methyl ester. ⑥ Transesterification reaction: The temperature was raised to 177±2℃ under stirring, and the system pressure was maintained at -0.09 MPa for 4 hours. The methanol generated during the reaction was carried away by the negative pressure to generate crude antioxidant 1076. ⑦ Post-processing: Transfer the crude antioxidant 1076 to a crystallization kettle, and heat-melt it with the methanol recovered in step ② at a temperature of 60°C. The solvent for heat melting is methanol, and the amount of methanol added is 3.5 times the mass of crude 1076. Crystallize (using the recovered methanol) at a temperature of 42°C for 1 hour. After filtration, obtain the solid and the recovered mother liquor. Wash the solid and vacuum dry it at 40°C for 2 hours to obtain the white flocculent antioxidant 1076 product. The mother liquor is returned to step ① to begin the next cycle. The GC-processed product has a purity of 99.46%, a melting point of 51.4~52.0℃, a light transmittance of 98.6% at 425nm and 99.1% at 500nm, and a heating loss of 0.05%, which meets the industry standard (GB / T 3795-2022). This time, the savings in fresh 3,5-methyl ester were 22.15 / 170.3 = 13.0%, and the savings in fresh octadecyl alcohol were 10.76 / 150.0 = 7.17%. The above detailed description of the present invention is for illustrative purposes only and is not intended to limit the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the usage needs are met, they are all within the protection scope of the present invention.

Claims

1. A method for preparing antioxidant 1076 using recycled mother liquor from antioxidant 1076 production, characterized in that, Includes the following steps: ① Mother liquor treatment process: Collect the mother liquor produced after the synthesis reaction of antioxidant 1076 through crystallization and filtration processes, and filter the mother liquor; ② First vacuum distillation: Place the filtered mother liquor in the first vacuum distillation apparatus, collect the distilled methanol, and the remaining material is the residue; ③ Second vacuum distillation: The residue obtained in step ② is transferred to the second vacuum distillation apparatus to separate the mixed fraction containing unreacted 3,5-methyl ester and octadecyl alcohol; ④ Component measurement: Quantitative analysis was performed on the mixed fraction to determine the contents of 3,5-methyl ester and octadecyl alcohol, respectively; ⑤ Ingredients and replenishment: Based on the measurement results in step ④, calculate the amount of fresh 3,5-methyl ester and fresh octadecyl alcohol to be replenished according to the molar ratio of octadecyl alcohol to 3,5-methyl ester of 1:1.02 to 1:1.05; add the mixed fraction, the replenished fresh 3,5-methyl ester, the fresh octadecyl alcohol and the catalyst into the reaction vessel in proportion. ⑥ Transesterification reaction: Transesterification reaction was carried out at a reaction temperature of 175~185℃ and a pressure of -0.09MPa~-0.1MPa. After a reaction time of 4~5 hours, crude antioxidant 1076 was generated. ⑦ Post-processing: The crude antioxidant 1076 is subjected to hot melting, crystallization and filtration processes to obtain a recovered mother liquor and a solid. The solid is washed and dried to obtain the antioxidant 1076 product. The recovered mother liquor is returned to step ① to enter the next cycle process.

2. The method for preparing antioxidant 1076 by recycling the mother liquor of antioxidant 1076 production according to claim 1, characterized in that, The first vacuum distillation is carried out at a temperature of 40℃ to 65℃ and a pressure of -0.08MPa to -0.095MPa.

3. The method for preparing antioxidant 1076 by recycling the mother liquor of antioxidant 1076 production according to claim 1, characterized in that, The second vacuum distillation is carried out at a temperature of 120℃-205℃ and a pressure of -0.095MPa to -0.099MPa.

4. The method for preparing antioxidant 1076 by recycling the mother liquor of antioxidant 1076 production according to claim 1, characterized in that, The catalyst is zinc acetate dihydrate, dibutyltin dilaurate, or tetraisopropyl titanate, and the amount of catalyst added is 0.1% to 0.5% of the total mass of 3,5-methyl ester.

5. The method for preparing antioxidant 1076 by recycling the mother liquor of antioxidant 1076 production according to claim 1, characterized in that, In step ⑦, the solvent for hot melting is methanol, the hot melting temperature is 60℃~70℃, and the amount of hot melting solvent added is 2.5~3.5 times the crude weight of antioxidant 1076; the crystallization temperature is 40℃~42℃, and the crystallization time is 1~2 hours; the solvent for washing is methanol; the drying temperature is 40~45℃, and the drying time is 2~3 hours.