Cloth circulating dyeing process based on online regeneration of dye liquor

Abstract

The invention relates to the technical field of textile dyeing and finishing, and discloses a cloth circulating dyeing process based on dye liquor online regeneration, which comprises the following steps: firstly, preparing a dyeing working solution containing a core and shell structure block copolymer, and wrapping a core load in a hydrophobic core of the copolymer; immersing a fabric to be dyed into the working solution, heating, and promoting the core load to be released from the core and dye the fabric by triggering the morphological change of the copolymer, so as to obtain the used dye solution; the used dye liquor is subjected to in-situ regeneration treatment through an online system, then a concentrated solution is supplemented according to an online monitoring result, and finally the rebalance working solution capable of being used for follow-up batch circular dyeing is obtained. The pH response unit and the photocatalysis unit are integrated on the same polymer carrier, so that the synergistic effect of targeted capture and in-situ degradation of impurities is realized, the complex purification function is internalized in the dye liquor fluid, and the process equipment is greatly simplified.

Description

Technical Field

[0001] This invention relates to the field of textile dyeing and finishing technology, specifically to a fabric recycling dyeing process based on online dye liquor regeneration. Background Technology

[0002] Textile dyeing, as a fundamental sector of modern manufacturing, is closely related to the consumption of water and energy resources. With increasingly stringent environmental regulations and rising production costs, achieving closed-loop recycling of dyeing wastewater while ensuring product quality has become a key technological requirement for the industry's sustainable development. Simultaneously, consumer demand for textiles has expanded from simply aesthetic color to include functional properties such as UV protection and photochromic properties, posing new and higher integration requirements for traditional dyeing processes.

[0003] To address the challenges of dye liquor recycling, a series of post-dyeing wastewater treatment solutions have been developed. Among them, external purification systems, represented by advanced oxidation processes (AOPs) and membrane separation technologies, constitute the current mainstream solutions. These systems are typically installed as independent units downstream of dyeing equipment, enabling advanced treatment of dyeing wastewater. Advanced oxidation processes generate strong oxidizing free radicals to mineralize and decompose large molecular organic pollutants in the wastewater; while membrane separation technologies utilize physical barriers to effectively retain suspended solids, colloids, and some dissolved macromolecules, thereby obtaining high-quality reclaimed water. These technologies have demonstrated strong purification capabilities and applicability in treating high-concentration, recalcitrant industrial wastewater.

[0004] However, existing technologies still exhibit inherent limitations in practical applications. First, external centralized purification systems lack necessary selectivity during the treatment process. They cannot effectively distinguish between harmful hydrolyzed impurities in the dye liquor and residual dye molecules that still have dyeing value. Often, while removing contaminants, they also cause the loss of effective dye, increasing operating costs. Second, a more fundamental contradiction exists inside the dyeing tank: the high-temperature environment required for dyeing is precisely the root cause of dye hydrolysis and impurity generation. Existing technologies are all "post-processing" and cannot intervene in the dyeing process itself, leaving them helpless in addressing the stability issues of dyes in high-temperature water bath environments. Finally, in terms of achieving fabric functionalization, traditional processes strictly separate dyeing and functional finishing into two independent, sequential steps. This model not only lengthens the production cycle and accumulates energy consumption but also introduces additional control challenges to the consistency of the final product's quality due to the fragmented process. To address these issues, those skilled in the art have proposed a fabric recycling dyeing process based on online dye liquor regeneration. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a fabric recycling dyeing process based on online dye liquor regeneration. This solves the problem in existing fabric recycling dyeing processes where the continuous accumulation of dye hydrolysis products and auxiliary impurities in the dye liquor limits the number of times the dye liquor can be recycled and adversely affects the quality stability of the final dyed product.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: a fabric recycling dyeing process based on online dye liquor regeneration. The core of this process lies in the use of a specially designed multi-response intelligent microemulsion. The carrier of this microemulsion has specific and independent response capabilities to three different physicochemical signals: temperature, pH, and light.

[0007] By programmatically controlling these external signals, this invention integrates multiple functional steps, such as controlled release of dyes, targeted capture of impurities, and in-situ degradation, into a continuous and automated closed-loop process, thereby achieving online purification and regeneration of dye liquor without interrupting dyeing production.

[0008] The specific technical solution for this process is as follows: The process includes the following steps: First, a staining working solution is prepared, which contains a core-shell structured amphiphilic block copolymer and a core loading material encapsulated in the hydrophobic core of the block copolymer.

[0009] Subsequently, the fabric to be dyed is immersed in the dyeing working solution, and by raising the temperature to a preset dyeing temperature, the block copolymer undergoes a morphological change. This morphological change causes the core load to be released from the hydrophobic core and dyed onto the fabric to be dyed, thereby obtaining the dyed fabric and the used dyeing working solution.

[0010] Next, the used staining working solution is introduced into an online regeneration system for programmed in-situ regeneration treatment to obtain the regenerated staining working solution.

[0011] Finally, based on the online monitoring results, a concentrated solution containing the block copolymer and the core loading material is added to the regenerated dyeing working solution to obtain a rebalanced dyeing working solution, which can be directly used for the cyclic dyeing of subsequent batches of fabric.

[0012] Preferably, the step of preparing the staining working solution includes: Provides dye components and functional auxiliary components as core loading materials; Provided as a carrier for a core-shell structured amphiphilic block copolymer, having a hydrophobic core segment and a hydrophilic shell segment, wherein a temperature-sensitive unit, a pH-responsive unit and a photocatalytic unit are covalently bonded to the hydrophilic shell segment; The dye component, functional auxiliary component, and core-shell structured amphiphilic block copolymer are mixed in an aqueous medium according to the following weight parts: the dye component is 2-8 parts, the functional auxiliary component is 1-5 parts, the core-shell structured amphiphilic block copolymer is 10-25 parts, and the aqueous medium is 800-1500 parts, thereby forming a microemulsion structure in which the core load is encapsulated in a hydrophobic core.

[0013] Preferably, a pretreatment step is included before immersing the fabric to be dyed into the dyeing working solution. This pretreatment step includes: The fabric to be dyed is immersed in a working solution of cationic modifier with a concentration of 20-40 g / L; The impregnated fabric is then dried at 100-120°C to fix the cationic modifier onto the fabric surface.

[0014] During the dyeing stage, the core mechanism lies in utilizing the physical properties of the temperature-sensitive units on the shell of the block copolymer. Specifically, the steps that trigger the morphological change of the block copolymer include: The temperature of the staining working solution is increased to above the low critical dissolution temperature of the thermosensitive unit at a heating rate of 1.5-2.5℃ / min. When the ambient temperature is higher than its low critical dissolution temperature, the thermosensitive unit undergoes a thermally induced phase transition and shrinks. This shrinkage mechanically compresses the hydrophobic core, thereby causing the core load to be released from the core.

[0015] After reaching the preset dyeing temperature, keep warm for 45-75 minutes to complete the dyeing process.

[0016] In the regeneration stage, the core mechanism lies in the synergistic function of the pH-responsive unit and the photocatalytic unit on the block copolymer shell. The programmed in-situ regeneration process includes: The first step is pH-triggered impurity capture. This step adjusts the pH of the used staining solution to a preset capture acidity to activate the pH-responsive unit to capture anionic impurities. In a preferred embodiment, this capture acidity is pH 4.5-5.5. Under these conditions, the pH-responsive unit protonates and becomes positively charged, adsorbing and enriching the anionic impurities through electrostatic attraction. The residence time of the staining solution at this acidity is 2-4 minutes.

[0017] The second step involves photo-triggered degradation. This step uses a light source to irradiate the staining working solution carrying the captured impurities, activating the photocatalytic unit to decompose the anionic impurities in situ. The light source is an ultraviolet light source with an intensity of 80-120 mW / cm². 2 The photocatalytic unit generates active oxide species under ultraviolet light irradiation, which decomposes the enriched anionic impurities into small molecule compounds in situ. The residence time of the dye solution under this light irradiation is 3-8 minutes.

[0018] The third step is to reset the system. This step restores the pH value of the degraded dyeing solution to the initial pH range of the dyeing process, preparing it for the next cycle.

[0019] To maintain the steady-state operation of the system, the step of replenishing the concentrated solution to the regenerated staining working solution includes: using an online spectrophotometer to monitor the concentration of the regenerated staining working solution in real time; and using a PLC controller to calculate the amount of concentrated solution to be replenished based on the real-time monitoring results. The replenishment is performed using a precision metering pump to maintain the concentration fluctuation of the staining working solution within ±3% to ±8%.

[0020] To achieve the above functions, the chemical structure of the core-shell structured amphiphilic block copolymer is specifically as follows: The hydrophobic core segment is a polystyrene segment or a polymethyl methacrylate segment; The temperature-sensitive unit is a poly(N-isopropylacrylamide) segment; The pH-responsive unit is a poly(diethylamino)methacrylate ethyl ester segment; The photocatalytic unit is titanium dioxide nanoparticles or zinc oxide nanoparticles modified with a silane coupling agent.

[0021] Preferably, the dyeing and regeneration steps are separately programmed and controlled by utilizing the independent response of the core-shell structured amphiphilic block copolymer to different physicochemical signals. This control mechanism includes: During the staining process, the temperature is independently raised to 110-130℃ to trigger the response of the temperature-sensitive unit, thereby enabling the controlled release of the core load. In the regeneration step, the pH value is adjusted independently and light is applied to trigger the response of the pH response unit and the photocatalytic unit respectively, thereby programmatically achieving the capture and degradation of impurities.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. This invention integrates a pH-responsive unit and a photocatalytic unit on the same polymer carrier, achieving a synergistic effect of targeted capture and in-situ degradation of impurities. It internalizes the complex purification function into the dyeing liquid itself, greatly simplifies the process equipment, changes the existing technology's reliance on external large-scale electrochemical or adsorption towers for "post-processing" treatment, and solves the inherent defects of its large system footprint and high operating costs.

[0023] 2. This invention utilizes the temperature-sensitive properties of the core-shell structure carrier to apply unprecedented programmed control to the dyeing process. During the heating stage, the dye is effectively encapsulated, and its hydrolysis side reaction in the high-temperature water bath is suppressed from the source. After reaching the dyeing temperature, the thermal phase transition of the carrier triggers the active release of the core load. Compared with the existing technology where the dye is always exposed to a harsh environment and can only passively accept subsequent purification, this invention cleverly integrates the two processes of dye protection and precise controlled release, solving the fundamental contradiction between dye stability and dyeing efficiency.

[0024] 3. This invention employs a technical solution that co-encapsulates dyes and functional auxiliaries within a microemulsion core, enabling the dyeing process and fabric functional finishing to be completed simultaneously. This produces unexpected technical effects, namely, solving the core technical problem of dye liquor recycling while endowing the final product with high-value-added characteristics such as photochromism. Compared to the complex process in existing technologies where dyeing and functional finishing must be implemented as separate steps, this invention achieves dual objectives through a single process step, significantly shortening the production cycle and reducing overall costs. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0028] Please see the appendix Figure 1 : Example 1: Preparation steps: 1. Preparation of smart carriers: In a reactor, 250 parts of styrene monomer, 3.5 parts of RAFT reagent (CPDTC), and 1.0 part of initiator (AIBN) for forming hydrophobic core segments are dissolved in 500 parts of tetrahydrofuran (THF).

[0029] After deoxygenation under nitrogen for 30 minutes, the system was heated to 70°C under nitrogen protection and reacted for 15 hours to obtain polystyrene macromolecular chain transfer agent (PS-RAFT).

[0030] Subsequently, 125 parts of polystyrene macromolecular chain transfer agent, 100 parts of temperature-sensitive unit monomer (N-isopropylacrylamide, NIPAM), 30 parts of pH-responsive unit monomer (ethyl 2-(diethylamino)methacrylate, DEAEMA) and 10 parts of photocatalytic unit (titanium dioxide nanoparticles modified with MPTMS surface) were dispersed in 600 parts of dimethylformamide (DMF) solvent.

[0031] Add 0.6 parts of initiator (AIBN), deoxygenate with nitrogen for 30 minutes, then heat the system to 75°C and react for 25 hours.

[0032] The product was subjected to precipitation, centrifugation, and washing, and then vacuum dried at 55°C for 18 hours to obtain a smart carrier powder as a core-shell structured amphiphilic block copolymer.

[0033] 2. Preparation of staining working solution: Dissolve 18 parts of the smart carrier obtained in step 1, 5 parts of the dye component (CI Disperse Blue 79 dye), and 3 parts of the functional auxiliary component (spiropyran) in 300 parts of tetrahydrofuran (THF).

[0034] The organic phase solution was added dropwise to 1200 parts of deionized water at a stirring rate of 1000 rpm and a stirring rate of 10 mL / min.

[0035] After stirring continuously for 5 hours, the mixture was transferred to a dialysis bag (molecular weight cutoff 12000 Da) and dialyzed against deionized water for 60 hours, with the external deionized water being replaced every 7 hours to obtain a smart microemulsion concentrate.

[0036] 3. Fabric pretreatment: The fabric to be dyed (polyester-cotton blended fabric) was immersed in a working solution of cationic modifier with a concentration of 30 g / L, and the pick-up rate was controlled at 80%. Then it was pre-dried at 110°C for 3 minutes.

[0037] 4. Staining and Regeneration: The pretreated fabric is put into the dyeing machine and the dyeing working solution prepared in step 2 is added at a liquor ratio of 1:12.

[0038] The dye bath temperature is heated to the preset dyeing temperature of 120℃ at a heating rate of 2.0℃ / min, and held at this temperature for 60 minutes.

[0039] After staining, the used staining working solution enters the online regeneration system for programmed in-situ regeneration treatment: first, the pH is adjusted to 5.0 by adding acid, and then left to stand for 3 minutes; It then enters the photoreactor at 100 mW / cm². 2 Irradiate under light intensity for 5 minutes; Finally, the pH was restored to 7.0 by adding alkali before being returned to the main tank.

[0040] 5. Fabric post-treatment: The dyed fabric is washed in hot water at 70°C, followed by soaping and cold water washing, and finally set and dried at 125°C for 12 minutes to obtain the finished product.

[0041] Example 2: Preparation steps: 1. Preparation of smart carriers: In a reaction vessel, 200 parts of styrene monomer, 2 parts of RAFT reagent (CPDTC), and 0.5 parts of initiator (AIBN) for forming hydrophobic core segments are dissolved in 400 parts of tetrahydrofuran (THF).

[0042] After deoxygenation under nitrogen for 20 minutes, the system was heated to 65°C under nitrogen protection and reacted for 12 hours to obtain polystyrene macromolecular chain transfer agent (PS-RAFT).

[0043] Subsequently, 100 parts of polystyrene macromolecular chain transfer agent (PS-RAFT), 80 parts of thermosensitive monomer (N-isopropylacrylamide, NIPAM), 20 parts of pH-responsive monomer (ethyl 2-(diethylamino)methacrylate, DEAEMA), and 5 parts of photocatalytic unit (MPTMS surface-modified titanium dioxide nanoparticles) were dispersed in 500 parts of In dimethylformamide (DMF) solvent.

[0044] Add 0.3 parts of initiator (AIBN), deoxygenate with nitrogen for 20 minutes, then heat the system to 70°C and react for 20 hours.

[0045] The product was subjected to precipitation, centrifugation, and washing, and then vacuum dried at 50°C for 12 hours to obtain a smart carrier powder as a core-shell structured amphiphilic block copolymer.

[0046] 2. Preparation of staining working solution: Dissolve 10 parts of the smart carrier obtained in step 1, 2 parts of the dye component (CI Disperse Blue 79 dye), and 1 part of the functional auxiliary component (spiropyran) in 200 parts of tetrahydrofuran (THF).

[0047] The organic phase solution was added dropwise to 800 parts of deionized water at a stirring rate of 5 mL / min at a stirring rate of 800 rpm.

[0048] After stirring continuously for 4 hours, the mixture was transferred to a dialysis bag (molecular weight cutoff 8000 Da) and dialyzed against deionized water for 48 hours, with the external deionized water being replaced every 8 hours to obtain a smart microemulsion concentrate.

[0049] 3. Fabric pretreatment: The fabric to be dyed (polyester-cotton blended fabric) was immersed in a working solution of cationic modifier with a concentration of 20 g / L, and the pick-up rate was controlled at 70%. Then it was pre-dried at 100°C for 2 minutes.

[0050] 4. Staining and Regeneration: The pretreated fabric is put into the dyeing machine and the dyeing working solution prepared in step 2 is added at a liquor ratio of 1:10.

[0051] Heat the dye bath to the preset dyeing temperature of 110℃ at a heating rate of 1.5℃ / min, and keep it at this temperature for 45 minutes.

[0052] After staining, the used staining working solution enters the online regeneration system for programmed in-situ regeneration treatment: first, the pH is adjusted to 4.5 by adding acid, and then left to stand for 2 minutes; It then enters the photoreactor at 80 mW / cm². 2 Irradiate under light intensity for 3 minutes; finally, restore the pH to 6.5 by adding alkali and then return it to the main tank.

[0053] 5. Fabric post-treatment: The dyed fabric is washed in hot water at 60°C, followed by soaping and cold water washing, and finally set and dried at 110°C for 8 minutes to obtain the finished product.

[0054] Example 3: Preparation steps: 1. Preparation of smart carriers: In a reactor, 300 parts of styrene monomer, 5 parts of RAFT reagent (CPDTC), and 1.5 parts of initiator (AIBN) for forming hydrophobic core segments are dissolved in 600 parts of tetrahydrofuran (THF).

[0055] After deoxygenation under nitrogen for 40 minutes, the system was heated to 75°C under nitrogen protection and reacted for 18 hours to obtain polystyrene macromolecular chain transfer agent (PS-RAFT).

[0056] Subsequently, 150 parts of polystyrene macromolecular chain transfer agent, 120 parts of temperature-sensitive unit monomer (N-isopropylacrylamide, NIPAM), 40 parts of pH-responsive unit monomer (ethyl 2-(diethylamino)methacrylate, DEAEMA) and 15 parts of photocatalytic unit (titanium dioxide nanoparticles modified with MPTMS surface) were dispersed in 700 parts of dimethylformamide (DMF) solvent.

[0057] Add 1.0 part AIBN, deoxygenate with nitrogen for 40 minutes, then heat the system to 80°C and react for 30 hours.

[0058] The product was subjected to precipitation, centrifugation, and washing, and then vacuum dried at 60°C for 24 hours to obtain a smart carrier powder as a core-shell structured amphiphilic block copolymer.

[0059] 2. Preparation of staining working solution: 25 parts of the smart carrier obtained in step 1, 8 parts of the dye component (CI Disperse Blue 79 dye), and 5 parts of the functional auxiliary component (spiropyran) were dissolved in 400 parts of tetrahydrofuran (THF).

[0060] The organic phase solution was added dropwise to 1500 parts of deionized water at a stirring rate of 15 mL / min at a stirring rate of 1200 rpm.

[0061] After stirring continuously for 6 hours, the mixture was transferred to a dialysis bag (molecular weight cutoff 14000 Da) and dialyzed against deionized water for 72 hours, with the external deionized water being replaced every 6 hours to obtain a smart microemulsion concentrate.

[0062] 3. Fabric pretreatment: The fabric to be dyed (polyester-cotton blended fabric) was immersed in a working solution of cationic modifier with a concentration of 40 g / L, and the pick-up rate was controlled at 90%. Then it was pre-dried at 120°C for 5 minutes.

[0063] 4. Staining and Regeneration: The pretreated fabric is put into the dyeing machine and the dyeing working solution prepared in step 2 is added at a liquor ratio of 1:15.

[0064] The dye bath temperature was increased to the preset dyeing temperature of 130℃ at a heating rate of 2.5℃ / min, and then kept at this temperature for 75 minutes.

[0065] After staining, the used staining working solution enters the online regeneration system for programmed in-situ regeneration treatment: first, the pH is adjusted to 5.5 by adding acid, and then left to stand for 4 minutes; It then enters the photoreactor at 120 mW / cm². 2 Irradiate with light intensity for 8 minutes; Finally, the pH was restored to 7.5 by adding alkali before being returned to the main tank.

[0066] 5. Fabric post-treatment: The dyed fabric is washed in hot water at 80°C, followed by soaping and cold water washing, and finally set and dried at 140°C for 15 minutes to obtain the finished product.

[0067] Comparative Example 1: Compared with Example 1, the difference is that in step 1, when preparing the smart carrier, the pH-responsive unit (DEAEMA monomer) and the photocatalytic unit (surface-modified TiO2 nanoparticles) were not added. Instead, only NIPAM monomer was grafted onto PS-RAFT to prepare a block copolymer with only temperature-sensitive responsiveness as the carrier. All other aspects are the same.

[0068] Comparative Example 2: Compared with Example 1, the difference is that in step 1, when preparing the smart carrier, no temperature-sensitive unit (NIPAM monomer) was added. Instead, only DEAEMA monomer and photocatalytic unit were grafted onto PS-RAFT to prepare a block copolymer with only pH response and photocatalytic functions as the carrier. All other aspects are the same.

[0069] Comparative Example 3: Compared with Example 1, the difference is that in the online regeneration step 4, the step of adjusting the pH of the dye solution to the capture acidity by adding acid is omitted, and the used dye solution directly enters the photoreactor for irradiation treatment. All other aspects are the same.

[0070] Comparative Example 4: Compared with Example 1, the difference lies in that, in the online regeneration step 4, after adjusting the pH of the dye solution to the capture acidity and holding it there, the step of entering the photoreactor for irradiation treatment is omitted, and the dye solution is directly subjected to pH restoration. All other steps are the same.

[0071] Comparative Example 5: Compared with Example 1, the difference is that the online regeneration step in step 4 is completely omitted. The dye solution after staining is not treated in any way, and its concentration is directly replenished and used for the next batch of staining. Everything else is the same.

[0072] Comparative Example 6: Compared with Example 1, the difference is that the fabric pretreatment step in step 3 was omitted, and the polyester-cotton blended fabric without any cationic modifier was directly dyed. All other aspects are the same.

[0073] Experiment 1: Experimental objective: This experiment aims to verify the synergistic effect and necessity of the pH response unit and photocatalytic unit integrated on the smart carrier in this invention for achieving efficient online regeneration of dye solution and maintaining the stability of cyclic dyeing.

[0074] Experimental group: Fabric sample and dye solution prepared in Example 1; Fabric sample and dye solution prepared in Comparative Example 1; Comparative Example 2: Fabric sample and dye solution prepared.

[0075] Experimental steps: 1. Sample preparation and collection: The three processes in the experimental groups were run continuously for 10 complete dyeing cycles under identical equipment and external conditions. After the first cycle, 50 mL of the "regenerated dye liquor" was taken from the regeneration system of each group and sealed for storage. At the same time, dyed fabric samples obtained in the first and tenth cycles of each group were collected and stored.

[0076] 2. Quality analysis of dye solution after regeneration: Using a UV-Vis spectrophotometer, with fresh, unused staining working solution as a blank control, the absorbance of the three "regenerated staining solutions" collected in step 1 was measured in the wavelength range of 350 nm to 450 nm. The highest intensity values ​​of the characteristic absorption peaks caused by hydrolysis impurities in this range for each sample were recorded and compared.

[0077] 3. Stability analysis of cyclic staining: Using an integrating sphere colorimeter, the dyed fabric sample obtained in the first cycle of each group was used as the standard sample, and the dyed fabric sample obtained in the 10th cycle of the corresponding group was measured. The total color difference value (ΔE) of the fabric in the 10th cycle of each group relative to the fabric in the first cycle was recorded and calculated (experimental data are shown in Table 1).

[0078] Table 1: Comparison of Regenerated Dye Solution Quality and Cyclic Dyeing Stability Data Group Intensity of impurity absorption peaks (Abs) in the regenerated dye solution Color difference value (ΔE) of fabric in cycle 10 Example 1 0.042 1.15 Comparative Example 1 0.867 12.28 Comparative Example 2 0.231 7.03 From Table 1, we can obtain: The experimental results of Example 1 demonstrate excellent performance, with extremely low impurity absorption peak intensity in the regenerated dye liquor and minimal color difference in the fabric after 10 consecutive cycles. This confirms the effectiveness of the complete technical solution of the present invention. The underlying mechanism lies in the fact that the pH-responsive unit integrated on the intelligent carrier successfully protonates and becomes positively charged under acidic regeneration conditions, efficiently capturing negatively charged anionic dye impurities generated by hydrolysis through electrostatic attraction. Subsequently, the impurities enriched on the carrier surface are degraded in situ by the adjacent photocatalytic unit under light irradiation. It is this precise synergistic mechanism of "first capturing and enriching, then degrading in situ" that ensures the continuous cleanliness of the dye liquor and the high consistency of dyeing quality.

[0079] The data from Comparative Example 1 showed drastically different results, with significantly increased absorption peak intensity of dye bath impurities and fabric color difference values. This is because its carrier removed two key functional units: pH response and photocatalysis. Consequently, during the regeneration process, the entire intelligent microemulsion system became inert to impurities and unable to perform any effective purification operations. Therefore, hydrolyzed impurities accumulated continuously in each cycle, severely polluting the dye bath environment and directly causing significant deviations in the dyeing effect of subsequent batches. This, conversely, demonstrates the necessity of the aforementioned functional unit combination for achieving the objectives of this invention.

[0080] The results of Comparative Example 2 revealed a deeper synergistic effect. Although its carrier retained the regeneration functional unit, resulting in a lower impurity absorption peak intensity than Comparative Example 1, its fabric color difference value was still much higher than that of Example 1. The mechanism is that the lack of a temperature-sensitive unit leads to a disordered and inefficient release process of the core load, with a large amount of dye failing to dye the fiber at the optimal time, resulting in decreased dye utilization and instability of the dye bath components. This indicates that regeneration capability alone is insufficient to guarantee the success of cyclic dyeing; it must be combined with an efficient and controllable dye release mechanism at the front end. This invention achieves an unexpectedly stable cyclic dyeing effect by integrating two seemingly unrelated functions—temperature-sensitive controlled release and pH / light-responsive regeneration—into the same carrier.

[0081] Experiment 2: Experimental objective: This experiment aims to verify the respective roles of the two independent steps, "pH-triggered capture" and "photo-triggered degradation," in the online regeneration process, and to elucidate the indispensable synergistic relationship between them.

[0082] Experimental group: The regenerated dye solution after treatment in Example 1; The regenerated dye solution after treatment in Comparative Example 3; The regenerated dye solution after treatment in Comparative Example 4.

[0083] Experimental steps: 1. Sample preparation and collection: Each of the three processes in the experimental group was run under identical equipment and external conditions for a complete staining cycle. Immediately after the cycle was completed, 100 mL of the "regenerated dye solution" was taken from the final outlet of each regeneration system, sealed, and stored for later use.

[0084] 2. Analysis of residual organic matter in dye liquor: The chemical oxygen demand (COD) values ​​of the three "regenerated dye liquor" samples collected in step 1 were determined using the dichromate method. This value is used to quantitatively characterize the total amount of residual organic impurities in the dye liquor.

[0085] 3. Analysis of the staining ability of the regenerated dye solution: The three types of "recycled dye liquor" collected in step 1 were used to dye new standard polyester-cotton white fabric under identical process conditions (fabric, liquor ratio, temperature, and time). After dyeing and post-treatment, the apparent color depth value (K / S value) of the obtained fabric samples was measured and recorded using a colorimeter (experimental data are shown in Table 2).

[0086] Table 2: Comparison of COD and staining capacity of regenerated dye solution Group COD (mg / L) of the dye solution after regeneration K / S value of fabrics dyed with recycled dye liquor Example 1 48 18.2 Comparative Example 3 265 13.8 Comparative Example 4 547 11.5 From Table 2, we can obtain: The results of Example 1 clearly demonstrate the effectiveness of the programmed regeneration process of this invention. The regenerated dye liquor exhibited the lowest COD value, and the fabric dyed with it had the highest K / S value, indicating highly efficient purification of the dye liquor. This is attributed to its unique two-step synergistic mechanism: First, by lowering the pH value, the pH-responsive unit is activated, making the microemulsion surface positively charged. This allows it to precisely capture and enrich negatively charged anionic impurities in the dye liquor through electrostatic attraction, acting like a "molecular target." Subsequently, when these highly enriched impurities enter the illumination zone, the adjacent photocatalytic unit can degrade them with extremely high efficiency. This programmed design of "enrichment first, degradation later" is the fundamental reason for achieving highly efficient purification.

[0087] Comparative Example 3 data demonstrates that the efficiency of the photocatalytic degradation step alone is limited. The COD value of the regenerated dye liquor and the K / S value of the dyed fabric are both inferior to those of Example 1. The mechanism lies in the absence of a pH-triggered capture step; the photocatalytic unit can only rely on random collisions with low-concentration, freely dispersed impurity molecules in the dye liquor, resulting in slow reaction kinetics and low degradation efficiency. Consequently, a large amount of impurities flows back to the main tank without treatment, significantly reducing the regeneration effect. This underscores the crucial role of the impurity pre-enrichment step in improving overall purification efficiency.

[0088] The results of Comparative Example 4 reveal from another perspective that both steps are indispensable. This group had the highest COD value and the worst dyeing ability. This is because, although the pH capture step successfully adsorbed impurities onto the microemulsion surface, the lack of a subsequent photodegradation step meant that these organic pollutants were not truly removed from the system; they merely changed from a free state to an adsorbed state, resulting in a persistently high total organic matter content (COD). These microemulsions carrying a large number of impurities may physically shield the fiber surface during subsequent dyeing, severely interfering with the normal dyeing process. This result strongly demonstrates that capture and degradation are a sequential and complementary whole. Only by combining the two in a specific order can a synergistic effect greater than the sum of its parts (1+1>2) be achieved, thus realizing the ultimate goal of this invention.

[0089] Experiment 3: Experimental objective: This experiment aims to verify the crucial role of a complete online regeneration system in maintaining the consistency of dyeing across multiple batches, and to clarify the necessity of the fabric cationization pretreatment step for improving dye uptake and product fastness.

[0090] Experimental group: Fabric sample prepared in Example 1; The fabric sample prepared in Comparative Example 5; Fabric sample prepared in Comparative Example 6.

[0091] Experimental steps: 1. Dye uptake rate test: Using the processes of Example 1 and Comparative Example 6, samples were taken from the dye bath before and after the initial dyeing process. The absorbance of the dye bath at the maximum absorption wavelength of the dye was measured using a UV-Vis spectrophotometer, and the dye concentration was calculated based on the standard curve. The dye uptake rate was then calculated and recorded.

[0092] 2. Multi-batch staining consistency test: The processes of Example 1 and Comparative Example 5 were run continuously for 5 dyeing cycles. The fabric obtained in the first cycle of each group was used as a standard sample, and the total color difference value (ΔE) of the fabric obtained in the fifth cycle was measured using a colorimeter. The cumulative color difference values ​​were recorded and compared.

[0093] 3. Color fastness to soap washing test: Fabric samples obtained from the first dyeing of Example 1 and Comparative Example 6 were taken respectively, and their color fastness to washing was tested according to GB / T 3921-2008 standard. The staining grade of each sample on the standard cotton lining fabric was evaluated and recorded (experimental data are shown in Table 3).

[0094] Table 3: Comparison Data of Process Integrity and Pretreatment Effect From Table 3, we can obtain: The comparison between Example 1 and Comparative Example 6 clearly demonstrates the decisive role of cationization pretreatment in fabric dyeing. The high dye uptake and excellent soaping resistance of the fabric in Example 1 are due to the pretreatment step introducing numerous positively charged sites onto the cotton fiber surface. These positively charged sites generate a strong electrostatic attraction with the intelligent microemulsion, which carries an overall negative potential, greatly enhancing the mass transfer driving force from the dye carrier to the fiber interface, thus achieving highly efficient dyeing. Simultaneously, this electrostatic bonding and the subsequent formation of covalent bonds result in stronger dye fixation, thus exhibiting higher color fastness. Comparative Example 6, lacking this crucial step, relies solely on weak van der Waals forces for dyeing, leading to insufficient dyeing and weak binding.

[0095] The significant color difference between Example 1 and Comparative Example 5 powerfully demonstrates the indispensability of the online regeneration system. Comparative Example 5 exhibited severe color difference accumulation during continuous production. The root cause was that, without the intervention of the online regeneration system, impurities such as hydrolyzed dyes and residual auxiliaries generated in each dyeing cycle were directly carried into the next batch. The concentration of these impurities continuously accumulated, altering the chemical environment of the dye bath, interfering with the thermodynamic equilibrium and kinetics of subsequent dyeing processes, ultimately leading to uncontrollable color drift. The online regeneration system in this invention precisely solves this problem by "resetting" the dye bath between batches, ensuring a high degree of consistency in the dyeing medium.

[0096] In summary, this experiment verified the innovation of this invention from two dimensions. The cationization pretreatment and online regeneration system solve the core problems of traditional cyclic dyeing from two different perspectives: "improving interface efficiency" and "maintaining media stability," respectively. The results of Comparative Example 6 show that even with a perfect regeneration system, qualified products cannot be obtained if the dyeing efficiency is low; while the results of Comparative Example 5 show that even if the initial dyeing efficiency is high, the process cannot achieve continuous and stable production without a regeneration system to maintain it. This invention achieves a robust, efficient, and high-quality cyclic dyeing process by non-obviously combining these two seemingly independent solutions to different technical problems, resulting in unexpected overall technical advantages.

[0097] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fabric recycling dyeing process based on online dye liquor regeneration, characterized in that, Includes the following steps: A staining working solution is prepared, wherein the staining working solution comprises a core-shell structured amphiphilic block copolymer and a core load encapsulated in the hydrophobic core of the block copolymer; The fabric to be dyed is immersed in the dyeing working solution, and the core and shell structure amphiphilic block copolymer is triggered to undergo morphological changes by heating to a preset dyeing temperature, which causes the core load to be released from the hydrophobic core and dyed onto the fabric to be dyed, thus obtaining the dyed fabric and the used dyeing working solution. The used staining working solution is introduced into an online regeneration system for programmed in-situ regeneration treatment to obtain a regenerated staining working solution. Based on the online monitoring results, a concentrated solution containing the core-shell structured amphiphilic block copolymer and the core loading material is added to the regenerated dyeing working solution to obtain a rebalanced dyeing working solution for subsequent batches of fabric cyclic dyeing.

2. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 1, characterized in that, The steps for preparing the staining working solution include: Provides dye components and functional auxiliary components as core loading materials; A carrier is provided as the core-shell structured amphiphilic block copolymer, having a hydrophobic core segment and a hydrophilic shell segment, wherein a temperature-sensitive unit, a pH-responsive unit and a photocatalytic unit are covalently bonded to the hydrophilic shell segment; The dye component, the functional auxiliary component, and the core-shell structured amphiphilic block copolymer are mixed in an aqueous medium according to parts by weight, wherein the dye component is 2-8 parts, the functional auxiliary component is 1-5 parts, the core-shell structured amphiphilic block copolymer is 10-25 parts, and the aqueous medium is 800-1500 parts, forming a microemulsion structure in which the core load is encapsulated in the hydrophobic core.

3. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 1, characterized in that, The step of triggering the morphological change of the core-shell structured amphiphilic block copolymer includes: The temperature of the staining working solution is increased to a level higher than the low critical dissolution temperature of the temperature-sensitive unit at a heating rate of 1.5-2.5℃ / min. The temperature-sensitive unit undergoes thermal phase transition shrinkage above its low critical dissolution temperature, which mechanically compresses the hydrophobic core, causing the core load to be released, and is kept at a preset staining temperature for 45-75 minutes.

4. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 1, characterized in that, The steps of the programmed in-situ regeneration process include: pH-triggered impurity capture includes adjusting the pH of the used staining working solution to a preset capture acidity to activate the pH response unit to capture anionic impurities; Photo-triggered degradation includes irradiating the staining working solution carrying the captured impurities with a light source to activate the photocatalytic unit to decompose the anionic impurities in situ. Perform a system reset, including restoring the pH of the staining working solution to the pH range of the initial staining process.

5. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 1, characterized in that, The step of replenishing the regenerated dyeing working solution with a concentrated solution containing the core-shell structured amphiphilic block copolymer and the core loading includes: The concentration of the regenerated staining working solution was monitored in real time using an online spectrophotometer; The amount of concentrate to be replenished is calculated using a PLC controller based on the real-time monitoring results. The replenishment is performed using a precision metering pump to maintain the concentration of the staining working solution within ±3% to ±8%.

6. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 1, characterized in that, Before immersing the fabric to be dyed into the dyeing working solution, a pretreatment step is also included, the pretreatment step comprising: The fabric to be dyed is immersed in a working solution of a cationic modifier with a concentration of 20-40 g / L; The fabric to be dyed after being impregnated is dried to fix the cationic modifier onto the fabric. The drying temperature is 100-120°C.

7. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 2, characterized in that, The chemical structural features of the core-shell structured amphiphilic block copolymer are as follows: The hydrophobic core segment is a polystyrene segment or a polymethyl methacrylate segment; The temperature-sensitive unit is a poly(N-isopropylacrylamide) segment; The pH-responsive unit is a poly(diethylamino)methacrylate ethyl ester segment; The photocatalytic unit is titanium dioxide nanoparticles or zinc oxide nanoparticles modified with a silane coupling agent.

8. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 4, characterized in that, The pH-triggered impurity capture step is further characterized by: The preset capture acidity is pH 4.5-5.5; The pH response unit is protonated and positively charged under the capture acidity, and adsorbs and enriches the anionic impurities through electrostatic attraction. The residence time of the used staining working solution under the capture acidity is 2-4 minutes.

9. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 4, characterized in that, The light-triggered degradation step is further characterized by: The light source is an ultraviolet light source with a light intensity of 80-120 mW / cm². 2 ; The photocatalytic unit generates active oxide species under the irradiation of the ultraviolet light source, which decomposes the enriched anionic impurities into small molecule compounds in situ. The residence time of the staining working solution carrying the captured impurities under the irradiation of the ultraviolet light source is 3-8 minutes.

10. The fabric recycling dyeing process based on online dye liquor regeneration according to claim 1, characterized in that, The core-shell structured amphiphilic block copolymer allows for programmed separation control of the dyeing and regeneration steps, including: During the staining process, the core loading material is released by independently raising the temperature to 110-130°C to trigger the response of the temperature-sensitive unit. In the regeneration step, the capture and degradation of impurities are achieved by independently adjusting the pH value and applying light to trigger the response of the pH response unit and the photocatalytic unit, respectively.

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