A method for dyeing silk with supercritical fluid as medium

Abstract

This invention relates to a silk dyeing method using supercritical fluid as a medium, belonging to the field of textile dyeing and finishing technology. The silk dyeing method of this invention uses a dyeing device as the generating device and includes the following steps: S1, placing a dyeing shaft with silk fixed on it, dye, fixing agent, and dyeing auxiliaries into a dye cup; S2, filling the dye cup with supercritical fluid, starting the supercritical dyeing system to drive the dye cup to rotate, causing relative motion between the dyeing shaft with silk fixed on it, the supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation; S3, separating and recycling the dye, fixing agent, dyeing auxiliaries, and supercritical fluid using a separation and recovery system; S4, cleaning the dyed silk and dye cup using a supercritical cleaning system. The silk dyeing method of this invention significantly improves the dye uptake rate and fixing efficiency after dyeing.

Description

Technical Field

[0001] This invention belongs to the field of textile dyeing and finishing technology, and particularly relates to a method for dyeing silk using supercritical fluid as a medium. Background Technology

[0002] Traditional textile dyeing methods use water as a solvent to dissolve dyes and then dye fabrics and yarns. After dyeing, washing and drying are required, resulting in significant water and energy consumption. During the dyeing process, auxiliary agents such as inorganic salts, surfactants, and chemical reagents like acids and alkalis are added to the dyeing solution. These auxiliary agents are not absorbed by the fabric, leading to mixed components in the dyeing wastewater and high treatment costs. Supercritical CO2 dyeing is a novel technology that uses CO2 fluid instead of water as a solvent to dissolve dyes and apply them to the fabric. Throughout the dyeing process, the low surface tension and excellent diffusion capacity of the fluid allow it to quickly carry the dye into the fiber. After dyeing, the dyeing temperature and pressure are reduced, the CO2 turns into a gas, and the dye dissolved in the supercritical CO2 becomes powder, both of which can be recycled and reused. Furthermore, the dyed fabric is dry and requires no subsequent drying. SCF-CO2 has minimal impact on the fabric, and all materials can be recycled and reused after dyeing, achieving a completely clean, green, and environmentally friendly process.

[0003] Compared to water, supercritical CO2 fluid exhibits better diffusivity and lower mass transfer performance, which facilitates the penetration of dyes and dyeing auxiliaries into textiles, making it a promising application. Among these applications, dyeing polyester fibers in supercritical CO2 fluid has yielded good results. However, natural fibers are limited in supercritical CO2 dyeing applications due to their inability to fully swell in this fluid and their lower color-fixing efficiency. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a silk dyeing method using supercritical fluid as the medium. This silk dyeing method can effectively improve the dyeing uptake and color fixation efficiency of silk in supercritical fluid, while causing less damage to the fabric.

[0005] The first objective of this invention is to provide a silk dyeing method using supercritical fluid as the medium, employing a dyeing apparatus as the generating device. The apparatus includes a supercritical dyeing system, a separation and recovery system, and a supercritical cleaning system. The supercritical dyeing system comprises a dyeing shaft and a dye cup. The dyeing shaft has several perforated holes distributed around its perimeter and in its central hollow tube. The silk dyeing method includes the following steps:

[0006] S1. Place the dyeing shaft with the silk fixed on it, the dye, the fixing agent and the dyeing auxiliary agent into the dye cup;

[0007] S2. Fill the dye cup with supercritical fluid, start the supercritical dyeing system to drive the dye cup to rotate. The dyeing shaft with silk fixed inside, supercritical fluid, dye, fixing agent and dyeing auxiliary agent move relative to each other and are uniformly circulated.

[0008] S3. Separate and recycle dyes, fixing agents, dyeing auxiliaries and supercritical fluids through a separation and recovery system for reuse;

[0009] S4. The dyed silk and dye cups are cleaned using a supercritical cleaning system.

[0010] In one embodiment of the present invention, before S1, the silk is further subjected to a pretreatment, wherein the pretreatment involves immersing the silk in water to make the moisture content of the silk 0.1%-250%.

[0011] In one embodiment of the present invention, in S1, the method of fixing the silk is winding or filling.

[0012] In one embodiment of the present invention, in S1, the silk is selected from silk fibers, silk yarns or silk fabrics.

[0013] In one embodiment of the present invention, in S1, the parent structure of the dye is an azo compound, and the active group is one or more of vinyl sulfone, vinyl group, and triazine group. The dye is soluble in a supercritical medium and can react with certain functional groups in silk, thereby becoming fixed inside the fiber.

[0014] In one embodiment of the present invention, in S1, the fixing agent is selected from amine compounds and their derivatives. The fixing agent is soluble in a supercritical medium, providing an alkaline environment inside the fiber without damaging the fiber.

[0015] Furthermore, in S1, the fixing agent is selected from octadecylamine.

[0016] In one embodiment of the present invention, in S1, the dyeing auxiliary agent is selected from one or more of water, alcohols, ketones, esters, and alkanes. The dyeing auxiliary agent can form an unstable complex with dye molecules through the dispersion force and induction force in the van der Waals forces between them, thereby promoting the dissolution of dye molecules in the supercritical medium and the dyeing of silk.

[0017] Furthermore, in S1, the dyeing auxiliary agent is selected from methyl salicylate.

[0018] In one embodiment of the present invention, in S1, the mass ratio of the dye, fixing agent and dyeing auxiliary agent is 1:240-260:20-30.

[0019] In one embodiment of the present invention, in S2, the supercritical fluid is selected from one or more of water, carbon dioxide, nitrogen, tetrafluoroethane, chlorofluorocarbons, methanol, ethanol, isopropanol, propane, n-butane, n-hexane, ethane, and ethylene.

[0020] In one embodiment of the present invention, in S2, the temperature of the uniform circulation treatment is 80℃-130℃, the pressure is 8MPa-28MPa, and the time is 10min-100min.

[0021] In one embodiment of the present invention, in S4, the cleaning temperature is 80℃-130℃, the pressure is 20MPa-30MPa, and the time is 10min-100min.

[0022] In one embodiment of the present invention, in S4, the cleaning is an online synchronous cleaning of the dyed silk and the dye cup.

[0023] In one embodiment of the present invention, in step S4, the cleaning specifically includes the following steps: continuously filling the dye cup with supercritical fluid and adjusting the outlet flow rate of the dye cup to make the temperature inside the cup 80℃-130℃ and the pressure 20MPa-30MPa, thereby utilizing the solubility of supercritical fluid and its mechanical scouring effect to continuously and synchronously clean and remove the floating dye on the silk fibers and the dye cup and other residual dyes online.

[0024] In one embodiment of the invention, the material of the dyeing shaft is selected from stainless steel.

[0025] A second objective of this invention is to provide silk obtained by the dyeing method described above.

[0026] The technical solution of the present invention has the following advantages compared with the prior art:

[0027] (1) The silk dyeing method of the present invention can, on the one hand, make the silk fabric fully expand so that the dye can quickly diffuse from the fiber surface to the fiber interior; on the other hand, it can make the supercritical fluid carry the dyeing auxiliaries into the fiber temporal part, provide an alkaline environment for the reaction of the active group with the silk, accelerate a series of reactions between the dye and the silk, and improve the color fixing efficiency.

[0028] (2) The silk dyeing method described in this invention is simple and easy to operate. The auxiliaries, fluids and dyes used can be recycled and reused, which solves the problem of difficult and costly treatment of dyeing waste liquid. In addition, the dyed fabrics are all dry and do not require subsequent drying, saving energy and meeting the current green development needs.

[0029] (3) The dyeing method of the present invention significantly improves the dye uptake rate and color fixation efficiency after dyeing. Attached Figure Description

[0030] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0031] Figure 1 The figures show the results of dyeing rate and color fixation efficiency of silk after dyeing in Examples 1-3 of the present invention; where (a)-(b) correspond to Examples 1-3 respectively;

[0032] Figure 2 The figures show the dyeing rate and color fixation efficiency of the dyed silk after dyeing in Examples 4-6 of the present invention; where (a)-(b) correspond to Examples 4-6 respectively.

[0033] Figure 3 The results of dyeing rate and color fixation efficiency of silk after dyeing in Examples 7-9 of the present invention are shown in the figure; where (a)-(b) correspond to Examples 7-9 respectively. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0035] In this invention, unless otherwise stated, the silk dyeing in the embodiments uses a dyeing device as the generating device, including a supercritical dyeing system, a separation and recovery system and a supercritical cleaning system. The supercritical dyeing system includes a dyeing shaft and a dye cup. Several perforated small holes are distributed around the dyeing shaft and on the central hollow tube. The material of the dyeing shaft is selected from stainless steel.

[0036] In this invention, unless otherwise stated, the structure of the dye is as follows:

[0037] Example 1

[0038] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0039] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0040] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing fixed silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 110℃, pressure 20MPa, time 40min.

[0041] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0042] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0043] Example 2

[0044] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0045] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0046] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing fixed silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 120℃, pressure 20MPa, time 40min.

[0047] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0048] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0049] Example 3

[0050] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0051] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0052] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 130℃, pressure 20MPa, time 40min.

[0053] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0054] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0055] Example 4

[0056] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0057] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0058] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing fixed silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 120℃, pressure 8MPa, time 40min.

[0059] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0060] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0061] Example 5

[0062] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0063] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0064] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 120℃, pressure 12MPa, time 40min.

[0065] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0066] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0067] Example 6

[0068] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0069] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0070] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing fixed silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 120℃, pressure 16MPa, time 40min.

[0071] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0072] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0073] Example 7

[0074] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0075] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0076] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing fixed silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 120℃, pressure 20MPa, time 40min.

[0077] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0078] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0079] Example 8

[0080] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0081] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0082] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 120℃, pressure 20MPa, time 80min.

[0083] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0084] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0085] Example 9

[0086] The silk dyeing method of the present invention using supercritical fluid as a medium specifically includes the following steps:

[0087] S1. Using a pipette, measure 5 mL of octadecylamine and 0.5 mL of methyl salicylate, and accurately weigh 0.02 g of dye using an electronic balance. Place all of these into the dyeing cup and stir thoroughly. Accurately weigh 1.00 g of silk fabric, soak it in deionized water for 1 minute, and then remove excess water to maintain a liquid carry-over rate of 150%. Evenly and smoothly wind the prepared silk fabric onto the dyeing shaft and then place it into the dyeing cup.

[0088] S2. Turn on the booster pump switch of the supercritical dyeing system to circulate the CO2 in the storage tank into the pipeline. Pressurize the dye cups using a quantitative pressurization system to ensure the carbon dioxide content in the dye cups is within the experimental requirements. Place the pressurized dye cups into the dyeing unit. The rotation of the dye cups drives their rotation, causing relative motion between the dyeing shaft (containing fixed silk), supercritical fluid, dye, fixing agent, and dyeing auxiliaries, resulting in uniform circulation. The operating conditions are: temperature 120℃, pressure 20MPa, time 100min.

[0089] S3. After dyeing is completed, the fluid in the dye cup in the dyeing unit is completely discharged, and the dye, fixing agent, dyeing auxiliary agent and supercritical fluid are separated and recycled through the separation and recovery system.

[0090] S4. Supercritical fluid is continuously introduced into the dye cup through a supercritical cleaning system, and the outlet flow rate of the dye cup is adjusted to make the temperature of the cleaning tank 80℃ and the pressure 25MPa. The fabric after depressurization is then cleaned with SCF-CO2 for 15 minutes. In this way, the solubility of supercritical fluid and its mechanical flushing effect are used to continuously and synchronously clean and remove the floating dye on the silk fibers and the residual dye inside the dye cup. After cleaning, the sample is put into a sealed bag and labeled for later use.

[0091] Test case

[0092] The dyeing rate and color-fixing efficiency of the dyed silk in Examples 1-9 were tested using the following methods:

[0093] The surface color depth (K / S) of the dyed fabric was measured using a colorimeter. A D65 light source, a 10° viewing angle, a 0.780 cm aperture, and a wavelength range of 350 nm to 700 nm were selected. The K / S values ​​of different sampling points (n=8) were measured. Finally, the arithmetic mean of the K / S values ​​at the wavelength of maximum characteristic absorption was calculated.

[0094] The tested fabric was placed in a Soxhlet extractor, and 200 mL of acetone was added. Extraction was carried out at 100 °C for 60 min. The surface color depth (K / S) of the extracted fabric was measured using a colorimeter with a D65 light source, a 10° viewing angle, a 0.780 cm aperture, and a wavelength range of 350 nm-700 nm. The K / S values ​​were measured at 8 sampling points at different locations. Finally, the arithmetic mean of the K / S values ​​at the wavelength of maximum characteristic absorption was calculated.

[0095] The color-fixing efficiency can be calculated using the following formula:

[0096]

[0097] The results are shown in Table 1 and Figure 1-3 As shown:

[0098] Example 1 3.41 68.51 Example 2 5.40 76.51 Example 3 4.49 75.12 Example 4 1.91 47.42 Example 5 3.78 62.02 Example 6 5.02 71.34 Example 7 5.93 86.66 Example 8 6.54 88.77 Example 9 6.92 88.70

[0099] From Table 1 and Figure 1-3 It can be seen that the dyeing method of this application significantly improves the dye uptake and fixation efficiency after dyeing. This is because silk fibers have nucleophilic groups that can react with the dichlorotriazine reactive group, mainly including the terminal amino group on the main chain of the silk fibroin macromolecule, the side chain amino group (-NH2) of the basic amino acid residue, the phenolic hydroxyl group (Ar-OH) in the tyrosine residue, and the alcoholic hydroxyl group (R-OH) of the serine residue. Simultaneously, octadecylamine can combine with water molecules on the wet fiber to produce OH-. - It reacts with -NH2 and -NH2 groups on protein fibers to form more free amino groups. Furthermore, the hydroxyl groups have a high degree of dissociation under weakly basic conditions, forming more strong nucleophilic hydroxyl anions. This promotes the nucleophilic substitution reaction between certain functional groups in silk and dichlorotriazine, causing the dye to adhere to the interior of the silk.

[0100] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for dyeing silk using supercritical fluid as the medium, characterized in that, The dyeing apparatus, using a dyeing device as the generating device, includes a supercritical dyeing system, a separation and recovery system, and a supercritical cleaning system. The supercritical dyeing system includes a dyeing shaft and a dye cup. The dyeing shaft has several perforated holes distributed around its perimeter and in its central hollow tube. The silk dyeing method includes the following steps. S1. Place the dyeing shaft with silk fixed on it, dye, fixing agent and dyeing auxiliary agent into the dyeing cup; the parent structure of the dye is an azo compound, and the active group is one or more of vinyl sulfone, vinyl and triazine; the fixing agent is selected from octadecyl tert-amine; the dyeing auxiliary agent is selected from methyl salicylate. S2. Supercritical fluid is introduced into the dye cup, and the supercritical dyeing system is started to drive the dye cup to rotate. The dyeing shaft with silk fixed inside, the supercritical fluid, the dye, the fixing agent and the dyeing auxiliary agent move relative to each other and are uniformly circulated. The supercritical fluid is selected from carbon dioxide. S3. Separate and recycle dyes, fixing agents, dyeing auxiliaries and supercritical fluids through a separation and recovery system for reuse; S4. The dyed silk and dye cups are cleaned using a supercritical cleaning system; Before S1, the process also includes pretreatment of the silk, which involves immersing the silk in water to reduce its moisture content to 0.1%-250%.

2. The silk dyeing method using supercritical fluid as a medium according to claim 1, characterized in that, In S1, the silk is selected from silk fibers, silk yarns, or silk fabrics.

3. The silk dyeing method using supercritical fluid as a medium according to claim 1, characterized in that, In S1, the mass ratio of the dye, fixing agent and dyeing auxiliary agent is 1:240-260:20-30.

4. The silk dyeing method using supercritical fluid as a medium according to claim 1, characterized in that, In S2, the temperature of the uniform circulation treatment is 80 ℃-130 ℃, the pressure is 8 MPa-28 MPa, and the time is 10 min-100 min.

5. The silk dyeing method using supercritical fluid as a medium according to claim 1, characterized in that, In S4, the cleaning temperature is 80 ℃-130 ℃, the pressure is 20 MPa-30 MPa, and the time is 10 min-100 min.

6. The silk dyeing method using supercritical fluid as a medium according to claim 1, characterized in that, In S4, the cleaning is a simultaneous online cleaning of the dyed silk and the dye cup.

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