Wastewater circulating dyeing process of high-elasticity dyed cloth

Abstract

The invention provides a wastewater circulating dyeing process for high-elasticity dyed cloth, which comprises the following steps: in a fiber pre-activation treatment step, performing puffing treatment on gray fabric through supercritical CO2 microbubbles in a supercritical dyeing machine, so as to form a nano-scale pore structure in the interior of the fiber of the gray fabric; transferring the bulked gray fabric into a treating fluid to perform grafting modification on the fiber surface of the gray fabric so as to form a positive charge layer; in the directional wastewater regeneration step, treating liquid waste liquid is collected, filtered through a ceramic membrane ultrafiltration unit, then subjected to electrodialysis through bipolar membrane electrodialysis equipment and recycled to obtain a cationic modifier, cellulase is added into the recycled cationic modifier for enzymolysis, and regenerated treating liquid containing glucose and the cationic modifier is obtained; in the dynamic circulating dyeing step, a dynamic pressure dyeing machine infiltrates regeneration treatment liquid into a pore structure in the grafted and modified gray fabric fiber, so that a nano cross-linked network structure is formed in the interior and on the surface of the gray fabric fiber.

Description

Technical Field

[0001] The present invention relates to the technical field of textile dyeing, and particularly to a wastewater recycling dyeing process for high-elasticity dyed fabrics. Background Art

[0002] As a key area of global water consumption and pollution in the textile industry, the wastewater discharge from the dyeing process accounts for more than 70% of the entire process. While pursuing color fastness and production efficiency, traditional dyeing processes often neglect the protection of the intrinsic mechanical properties of fibers and have not established a synergistic mechanism for wastewater recycling and fabric performance improvement. There are significant technical gaps in the existing technology system in terms of sustainability and functional upgrading, which are specifically manifested in the following two aspects:

[0003] I. Structural damage to the fabric elasticity by traditional dyeing processes. The conventional dyeing process adopts a linear process of "high-temperature dipping - multi-stage water washing", and its core steps include a pretreatment stage, a dyeing stage, and a post-treatment stage. In the above process, the combined effects of chemical erosion, thermal damage, and mechanical fatigue lead to a decrease in fiber crystallinity and an increase in molecular chain slippage, ultimately resulting in the deterioration of the tensile resilience of the dyed fabric.

[0004] II. Technical limitations of traditional wastewater treatment and reuse. The current wastewater treatment in the industry mainly adopts an "end-of-pipe treatment" mode, and its technical routes and defects include: physicochemical treatment, which cannot recover organic components with functional value; biological treatment, where microbial metabolites remain in the recycled water and inhibit dye penetration; membrane separation technology, when the residual Na2SO4 in the concentrate is reused in the dyeing process, it will cause the failure of cationic auxiliaries.

[0005] Although the international textile chemistry community has proposed the concept of wastewater as a resource in recent years, there are still two major bottlenecks at the engineering level: I. The disconnection between component regeneration and functional transformation. Existing recovery technologies mostly stay at the separation and purification stage and have not achieved the transformation of recovered substances into high-performance auxiliaries; II. The disconnection between structural reconstruction and performance response. Fiber modification mostly relies on externally added chemicals and fails to utilize the pores of the fiber itself as a nano-reactor to in-situ construct an elastic network.

[0006] Therefore, developing an innovative process that deeply couples wastewater recycling and elasticity enhancement, and realizing the synergistic gain of resource recycling and performance upgrading through the functional reorganization of wastewater components and the controllable reconstruction of fiber microstructure, has become the key path to breaking through the bottleneck of the sustainable development of the industry. Summary of the Invention

[0007] The present invention aims to solve the above technical problems and provides a wastewater recycling dyeing process for high-elasticity dyed fabrics.

[0008] The technical solution of the present invention is a waste water recycling dyeing process for high-elasticity dyed cloth, including successively carried out steps of fiber pre-activation treatment, waste water directional regeneration, and dynamic cycle dyeing;

[0009] In the fiber pre-activation treatment step, the grey cloth is puffed by supercritical CO2 microbubbles in a supercritical dyeing machine, and the treatment pressure is 8 - 12 MPa, and the treatment temperature is 40 - 50 °C, so as to form a nano-scale pore structure inside the grey cloth fibers. The puffed grey cloth is transferred to a treatment liquid containing 0.5 - 1.2% quaternary ammonium salt type cationic modifier for surface grafting modification of the grey cloth fibers to form a positive charge layer;

[0010] In the waste water directional regeneration step, the treatment liquid waste is collected, first filtered by a ceramic membrane ultrafiltration unit, and then electrodialyzed by a bipolar membrane electrodialysis device to recover the cationic modifier. Then, 0.3 - 0.5 g / L of cellulase is added to the recovered cationic modifier for enzymatic hydrolysis to obtain a regenerated treatment liquid containing glucose and cationic modifier;

[0011] In the dynamic cycle dyeing step, a dynamic pressure dyeing machine infiltrates the regenerated treatment liquid into the pore structure inside the grafting-modified grey cloth fibers, and the pressure of the dynamic pressure dyeing machine changes periodically within the range of 0 - 10 MPa, so as to form a nano-crosslinked network structure inside and on the surface of the grey cloth fibers.

[0012] As an implementation manner, in the fiber pre-activation treatment step, when puffing the grey cloth, the diameter of the microbubbles is controlled to be 50 - 200 nm.

[0013] As an implementation manner, in the fiber pre-activation treatment step, an on-line pressure sensor monitors the pressure change in the treatment chamber of the supercritical dyeing machine in real time, and adjusts the flow output of the high-pressure plunger pump and the opening degree of the back pressure valve of the supercritical dyeing machine according to the real-time monitoring value of the on-line pressure sensor, so that the treatment pressure in the treatment chamber of the supercritical dyeing machine changes within the range of 8 - 12 MPa according to a preset curve.

[0014] As an implementation manner, in the waste water directional regeneration step, the operating voltage gradient of the bipolar membrane electrodialysis device is 15 - 25 V / cm.

[0015] As an implementation manner, in the dynamic cycle dyeing step, the pressure loading of the dynamic pressure dyeing machine includes

[0016] The first stage: linear loading;

[0017] The second stage: stepped loading;

[0018] The third stage: oscillatory unloading.

[0019] As an implementation method, in the first stage, the pressure is linearly loaded from 0 to 5 MPa and lasts for 5 - 8 minutes.

[0020] As an implementation method, in the second stage, the pressure is stepwise loaded from 5 MPa to 10 MPa, with a gradient span of 1 MPa for each step, and each step is maintained for 2 minutes.

[0021] As an implementation method, in the third stage, the pressure is oscillatingly unloaded from 10 MPa to 0, with a frequency of 0.5 - 1.2 Hz.

[0022] As an implementation method, the supercritical dyeing machine, the modification treatment tank, and the dynamic pressure dyeing machine are connected by stainless - steel pipes, and a pneumatic diaphragm pump is provided in the stainless - steel pipes to enable the directional transfer of the greige fabric between each work station.

[0023] As an implementation method, the stainless - steel pipe has a PTFE lining.

[0024] The beneficial effect of the present invention compared with the prior art is that for the wastewater - recycling dyeing process of the high - elastic dyed fabric, by establishing a path for directional extraction of wastewater components, functional recombination, and fiber structure reconstruction, the effective components in the wastewater are converted into elastic enhancers, forming a sustainable process cycle of using waste to enhance elasticity.

[0025] In the fiber pre - activation treatment step, the greige fabric is puffed by supercritical CO2 micro - bubbles, so that nano - scale pore structures are formed inside the fibers and the porosity of the greige fabric is increased. The puffed greige fabric is transferred to the treatment liquid for surface graft modification of the greige fabric fibers to form a positive - charge layer. The positive - charge layer strongly adsorbs anionic dyes, improving the dye uptake rate. The positive - charge layer provides reaction sites for the subsequent enzymatic hydrolysis products, promoting the Maillard cross - linking reaction.

[0026] In the wastewater directional regeneration step, the wastewater containing unreacted cationic modifier is collected, first filtered by a ceramic - membrane ultrafiltration unit, and then electrodialyzed by a bipolar - membrane electrodialysis device. After the coupled treatment of ultrafiltration and electrodialysis, the ultrafiltration retains the macromolecular cationic modifier to form a concentrated cationic modifier, and the electrodialysis removes small - molecule salts to avoid salt interference in the subsequent enzymatic hydrolysis reaction, thus achieving precise separation and functional recombination of wastewater components. Then, cellulase is added to the recovered cationic modifier for enzymatic hydrolysis to obtain a regenerated treatment liquid containing glucose and cationic modifier. The role of the enzymatic hydrolysis recombination process is to decompose the short fibers in the wastewater to avoid clogging the pore structures inside the greige fabric fibers. The glucose produced by enzymatic hydrolysis serves as the reducing sugar for the Maillard reaction and condenses with the amino group of the cationic agent to form a cross - linked network. The cationic agent provides positive - charge anchor points to promote the directional deposition of the cross - linker on the fiber surface.

[0027] In the dynamic cyclic dyeing step, the regeneration treatment liquid penetrates into the pore structure inside the fibers of the graft-modified grey cloth through a dynamic pressure dyeing machine. The high-pressure penetration stage expands the pores and increases the penetration depth. The low-pressure rebound stage shrinks the pores. When the pressure drops suddenly, the pores of the fibers rebound, and mechanical extrusion promotes the directional arrangement of crosslinking agent molecules inside the pores. Since the crosslinking network can store elastic potential energy, the elastic recovery rate of the dyed cloth is improved. Thus, the synergistic gain of resource recycling and performance upgrading is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flowchart of the wastewater recycling dyeing process for the high-elasticity dyed cloth provided by the embodiment of the present invention;

[0029] Figure 2 It is a block diagram of the production line of the wastewater recycling dyeing process for the high-elasticity dyed cloth provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following will clearly and completely describe the above and other embodiments and advantages of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments.

[0031] In one embodiment, as Figure 1 and Figure 2 shown.

[0032] A wastewater recycling dyeing process for a high-elasticity dyed cloth provided by this embodiment includes a fiber pre-activation treatment step, a wastewater directional regeneration step, and a dynamic cyclic dyeing step that are carried out in sequence; in the fiber pre-activation treatment step, the grey cloth is puffed by supercritical CO2 microbubbles in a supercritical dyeing machine, and the treatment pressure is 8 - 12 MPa, and the treatment temperature is 40 - 50 °C, so as to form a nano-scale pore structure inside the grey cloth fibers. The puffed grey cloth is transferred to a treatment liquid containing 0.5 - 1.2% quaternary ammonium salt type cationic modifier for surface graft modification of the grey cloth fibers to form a positive charge layer; in the wastewater directional regeneration step, the treatment liquid waste is collected, first filtered by a ceramic membrane ultrafiltration unit, and then electro-dialyzed by a bipolar membrane electro-dialysis device to recover the cationic modifier. Then, 0.3 - 0.5 g / L of cellulase is added to the recovered cationic modifier for enzymatic hydrolysis to obtain a regeneration treatment liquid containing glucose and cationic modifier; in the dynamic cyclic dyeing step, a dynamic pressure dyeing machine penetrates the regeneration treatment liquid into the pore structure inside the graft-modified grey cloth fibers, and the pressure of the dynamic pressure dyeing machine changes periodically within the range of 0 - 10 MPa, so as to form a nano-crosslinking network structure inside and on the surface of the grey cloth fibers.

[0033] In this embodiment, the wastewater recycling dyeing process for the high-elasticity dyed fabric forms a sustainable process cycle of "oriented extraction of wastewater components → functional recombination → fiber structure reconstruction", converting the effective components in the wastewater into elasticity enhancers to achieve the goal of using waste to enhance elasticity.

[0034] In this embodiment, the wastewater recycling dyeing process for the high-elasticity dyed fabric includes a fiber pre-activation treatment step, a wastewater oriented regeneration step, and a dynamic recycling dyeing step.

[0035] Among them, the grey fabric is first puffed by supercritical CO2 microbubbles in a supercritical dyeing machine. The microbubbles form nano-scale pore structures inside the fibers, which can increase the porosity of the grey fabric. Setting the treatment pressure above 8 MPa is a necessary condition to ensure that CO2 is in a supercritical state, and setting the treatment pressure below 12 MPa can avoid excessive energy consumption of the equipment. By combining the pressure parameters and temperature parameters, the puffing efficiency can be improved. After testing by mercury intrusion porosimetry, the fiber porosity increases to 30% at 8 MPa / 40 °C, and the fiber porosity reaches 45% at 12 MPa / 50 °C. The puffed grey fabric is transferred to a treatment solution containing 0.5 - 1.2% quaternary ammonium salt type cationic modifier for surface grafting modification of the fabric fibers to form a positive charge layer. The quaternary ammonium salt type cation is electrostatically combined with the negative charges on the surface of the fabric fibers to form a dense positive charge layer. The positive charge layer strongly adsorbs anionic dyes, improving the dye uptake rate. Moreover, the positive charge layer provides reaction sites for the subsequent enzymatic hydrolysis products (glucose), promoting the Maillard cross-linking reaction.

[0036] Next, the wastewater containing unreacted cationic modifier is collected and first filtered through a ceramic membrane ultrafiltration unit, and then electrodialyzed through a bipolar membrane electrodialysis device. After the coupled treatment of ultrafiltration and electrodialysis, the ultrafiltration retains the macromolecular cationic modifier to form a concentrated cationic modifier, and the electrodialysis removes small molecule salts to avoid salt interference with the subsequent enzymatic hydrolysis reaction. Thus, the precise separation and functional recombination of wastewater components are achieved, providing a high-purity medium for the subsequent integrated dyeing-crosslinking process. Then, 0.3 - 0.5 g / L of cellulase is added to the recovered cationic modifier for enzymatic hydrolysis to obtain a regenerated treatment solution containing glucose and cationic modifier. The role of the enzymatic hydrolysis recombination process is to decompose the short fibers in the wastewater to avoid clogging the pore structures inside the fabric fibers. The glucose produced by enzymatic hydrolysis serves as a reducing sugar for the Maillard reaction and condenses with the amino group (-NH2) of the cationic agent to form a crosslinking network. The cationic agent provides positive charge anchor points to promote the directional deposition of the crosslinking agent on the fiber surface.

[0037] Finally, the regeneration treatment liquid penetrates into the pore structure inside the graft-modified grey fabric fibers through a dynamic pressure dyeing machine. During the high-pressure penetration stage (0 → 10 MPa), the pores expand, and the 10 MPa high pressure forces glucose and cationic agents in the regeneration liquid to enter the fiber nano-pores, increasing the penetration depth. During the low-pressure rebound stage (10 → 0 MPa), the pores contract, and when the pressure drops suddenly, the fiber pores rebound, and mechanical extrusion promotes the directional arrangement of cross-linking agent molecules inside the pores. Multiple cycles form a density gradient cross-linking layer in the radial direction of the fiber, with a higher cross-linking density in the outer layer than in the inner layer. Because the cross-linking network can store elastic potential energy, the elastic recovery rate of the dyed fabric is improved.

[0038] In this embodiment, the production line for the wastewater recycling dyeing process of high-elasticity dyed fabric includes a supercritical dyeing machine, a modification treatment tank, a wastewater collection tank, a ceramic membrane unit, an electrodialysis device, an intermediate storage tank, an enzymatic hydrolysis reaction tank, and a dynamic pressure dyeing machine. Among them, the modification treatment tank is also connected to the dynamic pressure dyeing machine through a roller conveyor. The grey fabric after puffing treatment is transferred to the modification treatment tank, and after modification, it is sent into the dynamic pressure dyeing machine by the roller conveyor. The path of the treatment liquid is: supercritical dyeing machine → wastewater collection tank → ceramic membrane unit → electrodialysis device → intermediate storage tank → enzymatic hydrolysis reaction tank → dynamic pressure dyeing machine. The supercritical dyeing machine is equipped with a plunger pump and a back pressure valve for controlling the treatment pressure, and also has a circulating heat transfer oil system for controlling the treatment temperature.

[0039] In one embodiment, in the wastewater recycling dyeing process of the high-elasticity dyed fabric, when the grey fabric is puffed during the fiber pre-activation treatment step, the diameter of the microbubbles is controlled to be 50 - 200 nm.

[0040] In this embodiment, 50 - 200 nm microbubbles can penetrate into the fibril gaps of the fiber (width about 30 - 100 nm) and form uniform pores when expanding. Avoiding the diameter of the microbubbles being greater than 200 nm can prevent tearing of the fiber surface. And matching the bubble size with the pressure field (8 - 12 MPa) can ensure that CO2 is stably in the supercritical state.

[0041] In one embodiment, in the wastewater recycling dyeing process of the high-elasticity dyed fabric, during the fiber pre-activation treatment step, an on-line pressure sensor monitors the pressure change in the treatment chamber of the supercritical dyeing machine in real time, and adjusts the flow output of the high-pressure plunger pump and the opening degree of the back pressure valve of the supercritical dyeing machine according to the real-time monitoring value of the on-line pressure sensor, so that the treatment pressure in the treatment chamber of the supercritical dyeing machine changes within the range of 8 - 12 MPa according to a preset curve.

[0042] In this embodiment, by setting an on-line pressure sensor for real-time monitoring, CO2 leakage can be compensated and the pore generation rate can be maintained constant. Automatically adjusting the output of the plunger pump according to the fabric weight per unit area can reduce energy consumption.

[0043] In one embodiment, in the wastewater recycling dyeing process of the high-elasticity dyed fabric, in the wastewater directional regeneration step, the gradient of the operating voltage of the bipolar membrane electrodialysis device is 15 - 25 V / cm.

[0044] In this embodiment, by controlling the operating voltage of the bipolar membrane electrodialysis device, ion migration can be controlled. When the voltage is 15 V / cm, the migration rate of Na + is 1.2 mmol / (m 2 ·s), and when it reaches 25 V / cm, it reaches 2.5 mmol / (m 2 ·s), which improves the desalination rate.

[0045] In one embodiment, in the wastewater recycling dyeing process of the high-elasticity dyed fabric, in the dynamic cycle dyeing step, the pressure loading of the dynamic pressure dyeing machine includes a first stage: linear loading; a second stage: stepped loading; a third stage: oscillatory unloading. Among them, in the first stage, the pressure linearly increases from 0 to 5 MPa and lasts for 5 - 8 minutes. Among them, in the second stage, the pressure stepwise increases from 5 MPa to 10 MPa, with a gradient span of 1 MPa for each step, and each step is maintained for 2 minutes. Among them, in the third stage, the pressure oscillates and unloads from 10 MPa to 0, with a frequency of 0.5 - 1.2 Hz.

[0046] In this embodiment, the linear loading in the first stage can achieve gradual penetration. The linear loading from 0 → 5 MPa evenly fills the pores with the regenerant, avoiding pore collapse caused by sudden loading. The stepped loading in the second stage is divided into levels of 5 MPa, 6 MPa... 10 MPa, with each level maintained for 2 minutes, promoting the stepwise condensation of the Maillard reaction. The Maillard reaction is a non-enzymatic chemical reaction that occurs between reducing sugars (such as glucose) and amino compounds (such as the amino group in quaternary ammonium salts) under heating or high-pressure conditions, generating brown polymers and cross-linked structures. This cross-linked structure forms a three-dimensional network scaffold within the fiber pores, restricting the slippage of molecular chains. The cross-linked network can also store elastic potential energy. The oscillatory unloading in the third stage generates a shear force at a frequency of 0.5 - 1.2 Hz, inducing the directional arrangement of cross-linking agent molecules, thereby locking the cross-linked network.

[0047] In one embodiment, in the wastewater recycling dyeing process of the high-elasticity dyed fabric, the supercritical dyeing machine, the modification treatment tank, and the dynamic pressure dyeing machine are connected through stainless steel pipes, and a pneumatic diaphragm pump is provided in the stainless steel pipes to enable the directional transfer of the greige fabric between workstations. Moreover, the stainless steel pipes have a PTFE lining.

[0048] In this embodiment, the combination of 316L stainless steel and PTFE lining can avoid metal ion contamination.

[0049] The specific embodiments described above further elaborate in detail on the object of the invention, the technical solutions, and the beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not intended to limit the protection scope of the present invention. It is particularly pointed out that for those skilled in the art, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wastewater recycling dyeing process for high-elasticity dyed fabric, characterized in that, It includes a fiber pre-activation treatment step, a wastewater directional regeneration step, and a dynamic cycle dyeing step carried out in sequence; In the fiber pre-activation treatment step, the grey fabric is puffed by supercritical CO2 microbubbles in a supercritical dyeing machine, and the treatment pressure is 8 - 12 MPa, and the treatment temperature is 40 - 50 °C, so as to form a nano-scale pore structure inside the grey fabric fibers. The puffed grey fabric is transferred to a treatment liquid containing 0.5 - 1.2% quaternary ammonium salt type cationic modifier for surface graft modification of the grey fabric fibers to form a positive charge layer; In the wastewater directional regeneration step, the treatment liquid waste is collected, first filtered by a ceramic membrane ultrafiltration unit, and then electrodialyzed by a bipolar membrane electrodialysis device to recover the cationic modifier. Then, 0.3 - 0.5 g / L of cellulase is added to the recovered cationic modifier for enzymatic hydrolysis to obtain a regenerated treatment liquid containing glucose and the cationic modifier; In the dynamic cycle dyeing step, a dynamic pressure dyeing machine infiltrates the regenerated treatment liquid into the pore structure inside the graft-modified grey fabric fibers, and the pressure of the dynamic pressure dyeing machine varies periodically within the range of 0 - 10 MPa, so as to form a nano-crosslinked network structure inside and on the surface of the grey fabric fibers.

2. The wastewater recycling dyeing process of the high-elasticity dyed fabric according to claim 1, characterized in that, In the fiber pre-activation treatment step, when puffing the grey fabric, the diameter of the microbubbles is controlled to be 50 - 200 nm.

3. The wastewater recycling dyeing process of the high-elasticity dyed fabric according to claim 2, characterized in that, In the fiber pre-activation treatment step, an on-line pressure sensor real-time monitors the pressure change in the treatment chamber of the supercritical dyeing machine, and adjusts the flow output of the high-pressure plunger pump and the opening and closing degree of the back pressure valve of the supercritical dyeing machine according to the real-time monitoring value of the on-line pressure sensor, so that the treatment pressure in the treatment chamber of the supercritical dyeing machine changes within the range of 8 - 12 MPa according to a preset curve.

4. The wastewater recycling dyeing process of the high-elasticity dyed cloth according to claim 2, characterized in that, In the wastewater directional regeneration step, the operating voltage gradient of the bipolar membrane electrodialysis device is 15 - 25 V / cm.

5. The wastewater recycling dyeing process of the high-elasticity dyed cloth according to claim 2, characterized in that, In the dynamic cycle dyeing step, the pressure loading of the dynamic pressure dyeing machine includes The first stage: linear loading; The second stage: stepped loading; The third stage: oscillatory unloading.

6. The wastewater recycling dyeing process of the high-elasticity dyed fabric according to claim 5, characterized in that, In the first stage, the pressure is linearly loaded from 0 to 5 MPa and lasts for 5 - 8 minutes.

7. The wastewater recycling dyeing process of the high-elasticity dyed fabric according to claim 5, characterized in that, In the second stage, the pressure is stepped loaded from 5 MPa to 10 MPa, with each step gradient span being 1 MPa, and each step is maintained for 2 minutes.

8. The wastewater recycling dyeing process of the high-elasticity dyed cloth according to claim 5, characterized in that, In the third stage, the pressure is oscillatory unloaded from 10 MPa to 0, with a frequency of 0.5 - 1.2 Hz.

9. The wastewater recycling dyeing process of the high-elasticity dyed fabric according to claim 1, characterized in that, The supercritical dyeing machine, the modification treatment tank, and the dynamic pressure dyeing machine are connected by stainless steel pipes, and a pneumatic diaphragm pump is provided in the stainless steel pipes to enable the directional transfer of the grey fabric between each work station.

10. The wastewater recycling dyeing process of the high-elasticity dyed fabric according to claim 1, characterized in that, The stainless steel pipe has a PTFE lining.

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