Anthraquinone yellow recyclable coloring monomer, and preparation method and application thereof

Abstract

The application belongs to the technical field of organic synthesis and high polymer material, and specifically provides an anthraquinone yellow recyclable coloring monomer, a preparation method and application thereof. The anthraquinone yellow recyclable coloring monomer has an anthraquinone nucleus, two benzene sulfenyl substituents on the anthraquinone nucleus and a flexible connecting arm containing a terminal hydroxyl group formed by ring opening of an epoxy compound. The preparation method comprises: reacting diphenyl sulfenyl anthraquinone with an epoxy compound under the action of an acid catalyst, and separating and purifying the reaction product to obtain the anthraquinone yellow recyclable coloring monomer. The monomer can be used as a comonomer to participate in polyester synthesis and prepare a high color fastness yellow polyester. In the recycling process, the polyester main chain is depolymerized to generate recyclable diacid and diol, and the anthraquinone yellow recyclable coloring monomer is precipitated from the system due to hydrophobicity, is recycled through solid-liquid separation and is used again to prepare a colored polyester, so that the coloring monomer and the polyester raw material monomer in the colored polyester are recycled in coordination.

Description

Technical Field

[0001] This application belongs to the field of organic synthesis and polymer materials technology, and in particular relates to an anthraquinone yellow recyclable coloring monomer, its preparation method and application. Background Technology

[0002] Polyester materials, due to their excellent mechanical properties, chemical resistance, and processability, are widely used in fibers, films, beverage bottles, and engineering plastics. However, the coloring of polyester materials and their recycling after disposal remain challenges. Traditional polyester coloring methods mainly include: 1. Physical blending: Disperse dyes or pigments are melt-blended with polyester chips and then spun or molded. This method is simple, but suffers from problems such as colorant migration, insufficient color fastness, and difficulty in separation during recycling; 2. Copolymer coloring: Coloring monomers containing active groups (such as hydroxyl and carboxyl groups) are introduced into the polyester backbone, achieving permanent coloring through covalent bonding. This method can significantly improve color fastness, but during copolymerization, once the colorant enters the polyester backbone, it is "locked in." During chemical recycling, the colorant severely contaminates the recycled diacids, diols, and other monomer raw materials, limiting the use of recycled monomers to low-value-added products and failing to meet the requirements of high-end applications.

[0003] Yellow is one of the three primary colors that are indispensable in polyester coloring. At present, the yellow colorants used in polyester mainly include azo dyes, pyrazolone dyes and other disperse dyes or pigments. These dyes generally have the following problems: they do not have the property of reversible release in chemical recycling, they are difficult to separate from polyester monomers, some azo dyes have potential sensitization or carcinogenic risks, and their lightfastness and migration resistance need to be further improved.

[0004] Anthraquinone compounds possess excellent color fastness (especially light fastness) and chemical stability, making them an ideal class of high-performance chromophores. However, directly introducing traditional hydroxyanthraquinone yellow dye monomers into the polyester backbone often faces the following structural design challenges: 1. Maintaining a bright yellow hue while avoiding red shifts (towards orange or yellow) in absorption peaks caused by substituents; 2. Ensuring sufficient reactivity and stability of the hydroxyanthraquinone yellow dye monomers during polymerization while avoiding side reactions that lead to molecular weight reduction or color darkening; 3. Ensuring that the introduced hydroxyanthraquinone yellow dye monomers can break down under mild conditions, allowing for clean removal from the polyester backbone during chemical recycling without compromising the purity of the recycled monomers.

[0005] Therefore, developing a novel, brightly colored, highly polymerizable anthraquinone yellow recyclable coloring monomer that can be efficiently and completely recovered during polyester chemical recycling is of great significance for realizing a fully closed-loop cycle of colored polyesters. Summary of the Invention

[0006] To address the aforementioned issues, this application provides a recyclable anthraquinone yellow coloring monomer, its preparation method, and its application.

[0007] This application first provides a recyclable anthraquinone yellow coloring monomer having the following general formula and chemical structure: In the formula, A represents a hydrophobic linker.

[0008] Furthermore, the hydrophobic group is a substituted or unsubstituted alkylene group containing 2-6 carbon atoms formed by ring opening of an epoxy compound, and the substituent includes alkyl or phenyl groups containing 1-6 carbon atoms.

[0009] Furthermore, the substituted or unsubstituted alkylene groups containing 2-6 carbon atoms include, but are not limited to, propylene, methyl-substituted propylene, and phenyl-substituted ethylene.

[0010] This application also provides a method for preparing anthraquinone yellow recyclable coloring monomer, comprising the following steps: a) The diphenylthioanthraquinone was subjected to a ring-opening etherification reaction with an epoxide under the action of an acid catalyst to obtain the crude product; b) Separate and purify the crude product to obtain the target product.

[0011] Furthermore, the diphenylthioanthraquinone is prepared by a nucleophilic substitution reaction of a dihaloanthraquinone with thiophenol under alkaline conditions; the dihaloanthraquinone is one or more of 1,5-dichloroanthraquinone, 1,5-dibromoanthraquinone, 1,8-dichloroanthraquinone, and 1,8-dibromoanthraquinone.

[0012] Furthermore, the alkali is one or more of potassium carbonate, sodium carbonate, sodium hydroxide, and potassium hydroxide; the reaction solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; the reaction temperature is 60-120℃, and the reaction time is 2-12h.

[0013] Furthermore, in step a), the epoxy compound is isobutylene oxide or styrene oxide.

[0014] Furthermore, in step a), the acid catalyst is trifluoroacetic acid or p-toluenesulfonic acid.

[0015] Furthermore, in step a), the molar ratio of diphenylthioanthraquinone, epoxide, and acid catalyst is 1:(2.0-3.0):(0.1-0.5).

[0016] Furthermore, in step a), the solvent used in the reaction is a halosol.

[0017] Furthermore, the halogenated solvent is one or more of dichloromethane, dichloroethane, and hexafluoroisopropanol.

[0018] Furthermore, in step a), the reaction temperature is 0-40℃ and the reaction time is 4-18h.

[0019] Furthermore, the anthraquinone yellow recyclable coloring monomer is copolymerized with polyester monomers to prepare colored polyester.

[0020] Furthermore, the polyester monomer is one or more of diols, diacids, and diesters.

[0021] Furthermore, the polyester is one or more of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0022] Furthermore, the total molar amount of the polyester monomer to the molar ratio of the anthraquinone yellow recyclable coloring monomer is 100:(0.01-5).

[0023] Furthermore, the catalyst used in the copolymerization reaction is an antimony-based catalyst or a titanium-based catalyst.

[0024] Furthermore, the copolymerization reaction includes esterification and polycondensation; wherein the esterification reaction temperature is 240-260℃ and the polycondensation reaction temperature is 255-290℃.

[0025] A chemical recovery method for colored polyesters obtained using anthraquinone yellow recyclable coloring monomers includes the following steps: (1) The colored polyester and alcohol are subjected to alcoholysis reaction under the action of an alkaline catalyst. After the reaction is completed, water is added and the solid-liquid separation is performed to obtain the anthraquinone yellow recyclable coloring monomer. The colored polyester is obtained by copolymerization reaction of the anthraquinone yellow recyclable coloring monomer and the polyester monomer. (2) Add inorganic acid to the filtrate in (1), and obtain a dicarboxylic acid by acid precipitation, filtration and drying.

[0026] Furthermore, in step (1), the solid-liquid ratio of the colored polyester to the alcohol is 1:(5-20)g / mL.

[0027] Furthermore, in step (1), the alkaline catalyst includes, but is not limited to, sodium hydroxide or sodium methoxide.

[0028] Furthermore, in step (1), the alcoholysis reaction is carried out at a temperature of 180-220°C for 2-6 hours.

[0029] Furthermore, in step (2), the inorganic acid is hydrochloric acid or sulfuric acid.

[0030] Furthermore, in steps (1) and (2), the obtained anthraquinone yellow recyclable coloring monomer and dicarboxylic acid are used to prepare colored polyesters.

[0031] Compared with the prior art, this application has the following beneficial effects: 1. This application connects a phenylthio group that imparts a yellow hue to the anthraquinone core and introduces two terminal hydroxyl groups through a flexible linker, enabling the anthraquinone yellow recyclable coloring monomer to be firmly embedded in the polyester backbone through copolymerization and participate in the synthesis of polyester. As a result, the prepared yellow polyester has a bright and stable yellow hue and high resistance to washing, rubbing and light fastness, which can meet the requirements of high-end textile and packaging materials.

[0032] 2. This application introduces hydrophobic groups into the molecular structure of the anthraquinone yellow recyclable coloring monomer, enabling the polyester to be completely and efficiently recycled after copolymerization of the anthraquinone yellow recyclable coloring monomer and polyester monomer, thus overcoming the technical difficulty of colorant recycling. This provides a practical solution for the chemical recycling of waste colored polyester textiles and packaging materials, reduces the environmental pressure of plastic waste, and improves the utilization efficiency of renewable resources. Attached Figure Description

[0033] Figure 1 This is a DSC diagram of the yellow polyester in Example 1.

[0034] Figure 2 This is the DSC diagram of the yellow polyester in Example 2. Detailed Implementation

[0035] To make the inventive objectives, technical solutions, and beneficial technical effects of this application clearer, the following detailed description is provided in conjunction with embodiments, clearly and completely describing the technical solutions in the embodiments of this application. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0038] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0039] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0040] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0041] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0042] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0043] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0044] In this application, room temperature refers to 0-40°C, including but not limited to 10-40°C, or further to 20-30°C.

[0045] Based on extensive experimental research, this application first provides a recyclable anthraquinone yellow coloring monomer with the following general formula and chemical structure: In the formula, A represents a hydrophobic linker.

[0046] In some embodiments of this application, the aryl thio groups and hydrophobic groups in the molecule synergistically increase the hydrophobicity of the anthraquinone yellow recyclable coloring monomer, and the two hydroxyl groups at the molecule's ends can serve as active groups for co-condensation with diacids. This anthraquinone yellow recyclable coloring monomer can provide a bright yellow color and exhibits good thermal stability at polyester polymerization temperatures.

[0047] In some embodiments of this application, the hydrophobic group is a substituted or unsubstituted alkylene group containing 2-6 carbon atoms formed by ring opening of an epoxy compound, and the substituent includes alkyl or phenyl groups containing 1-6 carbon atoms.

[0048] In some embodiments of this application, the substituted or unsubstituted alkylene containing 2-6 carbon atoms includes, but is not limited to, propylene, methyl-substituted propylene, or phenyl-substituted ethylene.

[0049] This application also provides a method for preparing anthraquinone yellow recyclable coloring monomer, comprising the following steps: a) The diphenylthioanthraquinone was subjected to a ring-opening etherification reaction with an epoxide under the action of an acid catalyst to obtain the crude product; b) Separate and purify the crude product to obtain the target product.

[0050] In some embodiments of this application, the diphenylthioanthraquinone can be prepared as follows: a dihaloanthraquinone, thiophenol, and a base are added to a polar aprotic solvent, and the reaction is carried out at a temperature under an inert atmosphere. After the reaction is completed, the mixture is cooled, water is added to precipitate the solid, and the solid is obtained by washing and recrystallization. This pretreatment step can clarify the source of the intermediate and ensure the reproducibility of the subsequent ring-opening etherification reaction of the epoxide compound.

[0051] In some embodiments of this application, the dihaloanthraquinone is one or more of 1,5-dichloroanthraquinone, 1,5-dibromoanthraquinone, 1,8-dichloroanthraquinone, and 1,8-dibromoanthraquinone.

[0052] In some embodiments of this application, the alkali is one or more of potassium carbonate, sodium carbonate, sodium hydroxide, and potassium hydroxide; the reaction solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone; the reaction temperature is 60-120℃, for example, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, and 120℃; and the reaction time is 2-12h, for example, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, and 12h.

[0053] In some embodiments of this application, in step a), the epoxy compound is isobutylene oxide or styrene oxide.

[0054] In some embodiments of this application, in step a), the acid catalyst is trifluoroacetic acid or p-toluenesulfonic acid.

[0055] In some embodiments of this application, in step a), the molar ratio of diphenylthioanthraquinone, epoxide, and acid catalyst is 1:(2.0-3.0):(0.1-0.5), for example, it can be 1:2.0:0.1, 1:2.1:0.2, 1:2.2:0.3, 1:2.5:0.4, or 1:3.0:0.5.

[0056] In some embodiments of this application, in step a), the solvent for the reaction is a halogenated solvent.

[0057] In some embodiments of this application, the halogenated solvent is one or more of dichloromethane, dichloroethane, and hexafluoroisopropanol.

[0058] In some embodiments of this application, in step a), the reaction temperature is 0-40°C, for example, it can be 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C, and the reaction time is 4-18h, for example, it can be 4h, 6h, 8h, 10h, 12h, 15h, or 18h.

[0059] In some embodiments of this application, the anthraquinone yellow recyclable coloring monomer is copolymerized with a polyester monomer to prepare a colored polyester; the polyester monomer is one or more of a diol, a diacid, and a diester.

[0060] In some embodiments of this application, the polyester is one or more of polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0061] In some embodiments of this application, the molar ratio of the total molar amount of the polyester monomer to the molar ratio of the anthraquinone yellow recyclable coloring monomer is 100:(0.01-5), for example, it can be 100:0.01, 100:0.05, 100:0.1, 100:0.2, 100:0.3, 100:0.4, 100:0.5, 100:0.6, 100:0.7, 100:0.8, 100:0.9, 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5, 100:5; within this range, an ideal dyeing depth can be obtained without significantly affecting the mechanical properties and spinnability of the polyester.

[0062] In some embodiments of this application, the catalyst used in the copolymerization reaction is an antimony-based catalyst or a titanium-based catalyst.

[0063] In some embodiments of this application, the copolymerization reaction includes esterification and polycondensation; wherein the esterification reaction temperature is 240-260°C, for example, 240°C, 250°C, or 260°C; and the polycondensation reaction temperature is 255-290°C, for example, 255°C, 270°C, 275°C, 280°C, or 290°C.

[0064] This application also provides a chemical recovery method for colored polyesters obtained using anthraquinone yellow recyclable coloring monomers, comprising the following steps: (1) The colored polyester and alcohol were subjected to alcoholysis reaction under the action of an alkaline catalyst. After the reaction was completed, water was added and the anthraquinone yellow recyclable coloring monomer was obtained by solid-liquid separation. (2) Add inorganic acid to the filtrate in (1), and obtain a dicarboxylic acid by acid precipitation, filtration and drying.

[0065] In some embodiments of this application, when the main chain of the colored polyester undergoes alcoholysis, a dicarboxylate and a diol are generated. At the same time, the carbon-oxygen bond between the anthraquinone chromophore and the polyester main chain breaks, releasing the anthraquinone yellow recyclable coloring monomer. After dilution with water, the anthraquinone yellow recyclable coloring monomer precipitates out due to its low solubility or hydrophobic effect. The dicarboxylate in the filtrate is obtained after acid precipitation, filtration, washing, and drying.

[0066] The aforementioned "one-pot" alkaline alcoholysis process can complete polyester depolymerization and coloring monomer release in the same reaction system. The recovery steps are simple, energy consumption is low, equipment investment is small, and the recovered dicarboxylic acid and coloring monomers are of high purity and can be directly used for the reproduction of high value-added products.

[0067] In some embodiments of this application, in step (1), the solid-liquid ratio of the colored polyester to the alcohol is 1:(5-20) g / mL, for example, it can be 1:5, 1:8, 1:10, 1:12, 1:15, 1:18, or 1:20.

[0068] In some embodiments of this application, the alkaline catalyst in step (1) includes, but is not limited to, sodium hydroxide or sodium methoxide.

[0069] In some embodiments of this application, in step (1), the temperature of the alcoholysis reaction is 180-220°C, for example, it can be 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, or 220°C, and the reaction time is 2-6 hours, for example, it can be 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours.

[0070] In some embodiments of this application, in step (2), the inorganic acid is hydrochloric acid or sulfuric acid.

[0071] In some embodiments of this application, in steps (1) and (2), the anthraquinone yellow recyclable coloring monomer and dicarboxylic acid obtained are used to prepare colored polyesters, achieving multiple recycling.

[0072] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0073] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0074] Example 1 The method for preparing the anthraquinone yellow recyclable coloring monomer in this embodiment includes the following steps: a) Add 500 mL of dichloromethane to a 1 L reactor, followed by 0.1 mol of 1,5-diphenylthioanthraquinone and 0.22 mol of isobutylene oxide. Add 0.05 mol of trifluoroacetic acid dropwise at 0 °C and stir the reaction for 15 h to obtain the crude product. b) Dilute the crude product with water and remove the solvent by rotary evaporation to precipitate the product. After filtration, wash the filter cake with 5% sodium bicarbonate and water, and then recrystallize it with acetone to obtain the target product. The 1H NMR spectra of the anthraquinone yellow recyclable coloring monomer prepared in this embodiment are as follows: 1H NMR (500 MHz, CDCl3) δ 8.07 (dd, J = 7.7, 1.3 Hz, 2H), 7.67 (dd, J= 7.6, 6.9 Hz, 2H), 7.60 (dd, J = 7.0, 1.3 Hz, 2H), 7.26–7.21 (m, 4H), 7.21–7.16 (m, 4H), 3.70 (d, J = 6.6 Hz, 4H), 2.81 (t, J = 6.7 Hz, 2H), 1.35 (s, 10H); The preparation method of 1,5-diphenylthioanthraquinone in this embodiment includes the following steps: 1,5-Dichloroanthraquinone and thiophene were added to DMF in a molar ratio of approximately 1:2.5. Potassium carbonate was added as an acid-binding agent. The mixture was stirred at 125°C for 3 hours. After the reaction was completed by thin-layer chromatography, the reaction solution was cooled to room temperature and then placed in an ice bath at 0–5°C for 1 hour to crystallize. The resulting filter cake was washed successively with a mixture of 95% ethanol and 8% sodium hydroxide (volume ratio 1:1) and deionized water until neutral. Finally, it was dried under vacuum at 70°C to constant weight to obtain the final product. The method for preparing yellow polyester using the anthraquinone yellow recyclable coloring monomer in this embodiment is as follows: In a 2L polymerization reactor, 2.0 mol of purified terephthalic acid, 4.0 mol of ethylene glycol, 0.01 mol of anthraquinone yellow recyclable coloring monomer (0.5% of the molar amount of purified terephthalic acid), and 0.4 g of antimony glycolate catalyst were added. Under a nitrogen atmosphere, the temperature was gradually increased to 250℃ for esterification reaction until the water content reached more than 95% of the theoretical value. After esterification, low-vacuum pre-condensation (255℃, 500Pa, 30 min) and high-vacuum final condensation (275℃, <100Pa, about 1.5 hours) were carried out sequentially. The endpoint was determined by the stirring torque. The product was discharged, cooled, and pelletized to obtain a bright yellow polyester. The chemical recovery method for yellow polyester in this embodiment includes the following steps: (1) Take 50.0g of the yellow polyester prepared above, crush it and add it to the high pressure vessel, then add 500mL of ethylene glycol solution containing 3.0g of sodium hydroxide, and react at 180℃ for 3 hours. After the reaction is completed, pour it into 1L of hot water at 60℃ while it is still hot. Yellow solid precipitates immediately. After cooling to room temperature, filter it, wash the filter cake with warm water, and dry it to obtain 3.2g of anthraquinone yellow recyclable coloring monomer. According to HPLC analysis, the purity is 97% and the recovery rate is about 90%. (2) The pH of the filtrate from (1) was adjusted to 2 with concentrated hydrochloric acid, and a white precipitate was formed. After filtration, washing with water and drying, 40.8 g of terephthalic acid was obtained. HPLC analysis showed that the purity was 99.3% and it was almost colorless, which met the requirements for repolymerization.

[0075] Example 2 The method for preparing the anthraquinone yellow recyclable coloring monomer in this embodiment includes the following steps: a) Add 500 mL of dichloromethane to a 1 L reactor, followed by 0.1 mol of 1,8-diphenylthioanthraquinone and 0.22 mol of isobutylene oxide. Add 0.01 mol of p-toluenesulfonic acid in portions at 0 °C and stir for 15 h to obtain the crude product. b) Dilute the crude product with water and remove the solvent by rotary evaporation to precipitate the product. After filtration, wash the filter cake with 5% sodium bicarbonate and water, and then recrystallize it with acetone to obtain the target product. The 1H NMR spectra of the anthraquinone yellow recyclable coloring monomer prepared in this embodiment are as follows: 1H NMR (500 MHz, CDCl3) δ 8.07 (dd, J = 7.7, 1.3 Hz, 2H), 7.67 (dd, J= 7.6, 6.8 Hz, 2H), 7.60 (dd, J = 7.0, 1.3 Hz, 2H), 7.35–7.30 (m, 4H), 7.30–7.20 (m, 10H), 7.20–7.14 (m, 4H), 4.19 –4.07 (m, 6H), 2.74–2.66 (m, 2H); The preparation method of 1,8-diphenylthioanthraquinone in this embodiment includes the following steps: 1,8-Dichloroanthraquinone and thiophene were added to NMP in a molar ratio of approximately 1:2.5. Potassium carbonate was added as an acid-binding agent. The mixture was stirred at 120°C for 3 hours. After the reaction was completed by thin-layer chromatography, the reaction solution was cooled to room temperature and then placed in an ice bath at 0–5°C for 1 hour to crystallize. The resulting filter cake was washed successively with a mixture of 95% ethanol and 8% sodium hydroxide (volume ratio 1:1) and deionized water until neutral. Finally, it was dried under vacuum at 70°C to constant weight to obtain the final product. The method for preparing yellow polyester using the anthraquinone yellow recyclable coloring monomer in this embodiment is as follows: In a 2L polymerization reactor, 2.0 mol of purified terephthalic acid, 4.0 mol of ethylene glycol, 0.01 mol of anthraquinone yellow recyclable coloring monomer (0.5% of the molar amount of purified terephthalic acid), and 0.4 g of antimony glycolate catalyst were added. Under a nitrogen atmosphere, the temperature was gradually increased to 240℃ for esterification reaction until the water content reached more than 95% of the theoretical value. After esterification, low-vacuum pre-condensation (255℃, 500Pa, 30 min) and high-vacuum final condensation (275℃, <100Pa, about 1.5 hours) were carried out sequentially. The endpoint was determined by the stirring torque. The product was discharged, cooled, and pelletized to obtain a bright yellow polyester. The chemical recycling method for yellow polyester in this embodiment includes the following steps: (1) Take 50.0g of the yellow polyester prepared above, crush it and add it to a high pressure vessel, then add 500mL of ethylene glycol solution containing 5.0g of sodium hydroxide, and react at 180℃ for 3 hours with stirring. After the reaction is completed, pour it into 1L of hot water at 60℃ while it is still hot. A yellow solid will precipitate immediately. After cooling to room temperature, filter it, wash the filter cake with warm water, and dry it to obtain 4.1g of anthraquinone yellow recyclable coloring monomer. According to HPLC analysis, the purity is 98.1% and the recovery rate is about 88%. (2) The pH of the filtrate from (1) was adjusted to 2 with concentrated hydrochloric acid, and a white precipitate was formed. After filtration, washing with water and drying, 42.1 g of terephthalic acid was obtained. HPLC analysis showed that the purity was 99.5% and it was almost colorless, which met the requirements for repolymerization.

[0076] Blank comparison example Except for the absence of anthraquinone yellow recyclable coloring monomer, an uncolored PET control sample was prepared according to the preparation method of yellow polyester in Example 1. This control sample was used to compare the effects of anthraquinone yellow recyclable coloring monomer on the thermal properties and intrinsic viscosity of polyester.

[0077] Comparative Example 1 The coloring dye used in this comparative example is a commercial yellow disperse dye (CI Disperse Yellow 54). The method for preparing yellow polyester using the coloring dye in this comparative example is as follows: a commercial yellow disperse dye is melt-blended with PET polyester to prepare yellow PET masterbatch, and the yellow PET masterbatch is spun with PET chips to obtain yellow polyester fibers; The modified comparative example is a chemical recycling method for yellow polyester fibers, including the following steps: (1) Take 50.0g of the yellow polyester fiber prepared above, crush it and add it to the high pressure vessel. Add 500mL of ethylene glycol solution containing 3.0g sodium hydroxide and react at 180℃ for 3 hours. After the reaction is completed, pour it into 1L of hot water at 60℃ while it is still hot. No yellow solid precipitates. After cooling to room temperature, filter it. The coloring dye is completely dissolved and cannot be obtained by simple filtration. (2) The pH of the filtrate from (1) was adjusted to 2 with concentrated hydrochloric acid. After filtration, washing with water and drying, yellow terephthalic acid was obtained.

[0078] Performance testing 1. Thermal performance testing: The glass transition temperature To of the yellow polyester and uncolored PET in Examples 1 and 2 was tested using a differential scanning calorimeter (DSC) under a nitrogen atmosphere at a heating and cooling rate of 10°C / min. g Crystallization temperature T c and melting point T m The DSC charts of the yellow polyester in Examples 1 and 2 are shown below. Figure 1 and Figure 2 .

[0079] 2. Color and colorimetric testing: A colorimeter was used, according to CIE L. a b The colorimetric system was used to measure the L of the yellow polyester samples in Examples 1 and 2 under a D65 light source, a 10° standard observer, and SCI mode. a b The values ​​were calculated by taking the average of three different locations for each sample, and the results are shown in Table 1.

[0080] 3. Color fastness test: The yellow polyester obtained in Examples 1 and 2 was melt-spun into fibers. The color fastness to washing was tested according to GB / T3921-2008, the color fastness to rubbing was tested according to GB / T 3920-2008, and the color fastness to light was tested according to GB / T 8427-2019. The results are shown in Table 1.

[0081] 4. Intrinsic viscosity test: Using a fully automatic viscometer, referring to GB / T 14190-2017, the intrinsic viscosity of the yellow polyester and uncolored PET of Examples 1 and 2 was tested under the conditions of phenol / 1,1,2,2-tetrachloroethane (mass ratio 50:50) mixed solvent and 25°C. The intrinsic viscosity was used to evaluate the molecular weight and spinnability of the polyester. The results are shown in Table 1.

[0082] Table 1. Performance test results of colored polyester and uncolored PET in Examples 1-2 From Table 1 L a b The data show that the yellow polyesters obtained in Examples 1 and 2 are both high-brightness bright yellow. The thermal properties and intrinsic viscosity data show that the crystallization temperature and melting point of Examples 1 and 2 did not decrease significantly compared to uncolored PET, and the glass transition temperature remained essentially unchanged, indicating that the anthraquinone yellow recyclable coloring monomer of this application, after being copolymerized to color PET, still possesses good processability. The color fastness data shows that the yellow polyesters obtained in Examples 1 and 2 have high color fastness, indicating that the anthraquinone yellow recyclable coloring monomer, after covalently entering the polyester chain segment, has good wash resistance, abrasion resistance, and lightfastness stability.

[0083] A comparison of the examples and comparative examples shows that the anthraquinone yellow recyclable coloring monomer obtained in the examples, when applied to yellow polyester, can be recovered through solid-liquid separation during polyester chemical recycling. The recovered coloring monomer has high purity and can be directly recycled for the resynthesis of yellow polyester. Simultaneously, the terephthalic acid obtained through acid precipitation has high purity and a light color, meeting the requirements for repolymerization. Therefore, this application constructs a complete material recycling technology system from "coloring polymerization" to "depolymerization and recycling," providing feasible technical support for green and sustainable development in textiles, packaging, and other fields. In contrast, in Comparative Example 1, after physical coloring with a commercial yellow disperse dye, the coloring dye cannot be recovered through simple filtration and contaminates the terephthalic acid, causing it to appear distinctly yellow, requiring further purification before use in polyester synthesis.

[0084] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A recyclable anthraquinone yellow coloring monomer, characterized in that: It has the following general formula and chemical structure: In the formula, A represents a hydrophobic linker.

2. The method for preparing an anthraquinone yellow recyclable coloring monomer according to claim 1, characterized in that: Includes the following steps: a) The diphenylthioanthraquinone was subjected to a ring-opening etherification reaction with an epoxide under the action of an acid catalyst to obtain the crude product; b) Separate and purify the crude product to obtain the target product.

3. The method for preparing an anthraquinone yellow recyclable coloring monomer according to claim 2, characterized in that: In step a), the diphenylthioanthraquinone is prepared by a nucleophilic substitution reaction of dihaloanthraquinone and thiophenol under alkaline conditions; the dihaloanthraquinone is one or more of 1,5-dichloroanthraquinone, 1,5-dibromoanthraquinone, 1,8-dichloroanthraquinone and 1,8-dibromoanthraquinone.

4. The method for preparing an anthraquinone yellow recyclable coloring monomer according to claim 2, characterized in that: In step a), the molar ratio of diphenylthioanthraquinone, epoxide, and acid catalyst is 1:(2.0-3.0):(0.1-0.5).

5. The application of the anthraquinone yellow recyclable coloring monomer according to claim 1, characterized in that: The anthraquinone yellow can be recycled as a coloring monomer and copolymerized with polyester monomers to prepare colored polyesters.

6. The application of the anthraquinone yellow recyclable coloring monomer according to claim 5, characterized in that: The total molar amount of the polyester monomer to the molar ratio of the anthraquinone yellow recyclable coloring monomer is 100:(0.01-5).

7. A chemical recovery method for colored polyester obtained using the anthraquinone yellow recyclable coloring monomer described in claim 1, characterized in that: Includes the following steps: (1) The colored polyester and alcohol are subjected to alcoholysis reaction under the action of an alkaline catalyst. After the reaction is completed, water is added and the solid-liquid separation is performed to obtain the anthraquinone yellow recyclable coloring monomer. The colored polyester is obtained by copolymerization reaction of the anthraquinone yellow recyclable coloring monomer and the polyester monomer. (2) Add inorganic acid to the filtrate in (1), and obtain a dicarboxylic acid by acid precipitation, filtration and drying.

8. The chemical recovery method for colored polyester obtained by using anthraquinone yellow recyclable coloring monomers according to claim 7, characterized in that: In step (1), the alcoholysis reaction is carried out at a temperature of 180-220℃.

9. The chemical recovery method for colored polyester obtained using anthraquinone yellow recyclable coloring monomers according to claim 7, characterized in that: In step (2), the inorganic acid is hydrochloric acid or sulfuric acid.

10. A chemical recovery method for colored polyester obtained using anthraquinone yellow recyclable coloring monomers according to claim 7, characterized in that: In steps (1) and (2), the obtained anthraquinone yellow recyclable coloring monomer and dicarboxylic acid are used as raw materials to prepare colored polyester.

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