A supercritical carbon dioxide fluid anhydrous dye composition, dyeing process and its application in silk fabric
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HANGZHOU SIJIN NON-WOVEN CLOTH CO LTD
- Filing Date
- 2026-04-13
- Publication Date
- 2026-05-29
Smart Images
Figure CN122105883A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of textile dyeing and finishing technology, specifically to a supercritical carbon dioxide fluid anhydrous dye composition, dyeing process, and its application in silk fabrics. Background Technology
[0002] Supercritical carbon dioxide fluid dyeing technology is a green and environmentally friendly dyeing method that uses supercritical CO2 instead of traditional water as the dyeing medium. It boasts significant advantages such as being waterless, pollution-free, and energy-efficient, making it crucial for changing the current situation of high water consumption and large pollution discharge in the traditional textile printing and dyeing industry. Currently, this technology has been commercially applied in the dyeing of synthetic fibers such as polyester, but extending it to natural protein fibers such as silk still faces a series of technical challenges.
[0003] Silk, as a protein fiber, possesses unique molecular structure and physicochemical properties: its molecular chains contain a large number of polar functional groups such as amino and carboxyl groups, making it sensitive to heat and prone to yellowing and strength reduction under high-temperature conditions. However, existing supercritical CO2 dyeing technology mainly draws on polyester dyeing processes, with dyeing temperatures typically reaching 100-120℃. Directly applying this technology to silk results in severe heat damage to the silk fibers, failing to meet the quality requirements of high-end silk fabrics.
[0004] To address the issue of high-temperature damage, the dyeing temperature needs to be lowered to below 80°C. However, under low-temperature conditions, the solubility of disperse dyes in supercritical CO2 decreases sharply, resulting in low dye uptake and difficulty in achieving dark colors, creating a technical contradiction of "high temperatures damage fibers, low temperatures prevent dyeing." Even if the solubility problem is partially solved through dye structure modification or the addition of co-solvents, there is still a lack of strong interaction between the dye and polar silk fibers in the non-polar CO2 medium, making it difficult to achieve color fastness, especially wet rubbing fastness, to meet the standards for clothing.
[0005] To address these issues, research institutions both domestically and internationally have conducted extensive research. The team led by Long Jiajie at Soochow University has carried out continuous and in-depth research in this field and has made significant progress.
[0006] Chinese invention patent CN102392367B, published on July 24, 2013, discloses a "method for fixing reactive disperse dyes in a low-pressure carbon dioxide medium." This technology employs a stepwise process: first, the reactive disperse dye is adsorbed and dyed onto natural fibers in a supercritical CO2 fluid; then, the fabric is transferred to a fixing unit, where a fixing reaction is carried out in a low-pressure CO2 gas medium (1.0-6.0 MPa) using triethylenediamine as a catalyst. This method utilizes the catalyst to form unstable onium ion intermediates with the dye's reactive groups, increasing the reactivity between the dye's reactive groups and the functional groups on the fiber, thus achieving catalytic fixation of the dye on the fiber. The fixing efficiency can reach 78.8%-98.3%. However, this technology still has the following shortcomings: First, the step-by-step process of "dyeing + low-pressure fixing" requires two sets of equipment and two processing steps, which makes the process complex and the production efficiency low; Second, a catalyst needs to be introduced separately in the fixing stage, which fails to achieve the integration of dyeing and fixing in the same bath; Third, this technology is mainly for cotton fibers. Although the example mentions humidification treatment (100% moisture content), it is not used as a necessary technical feature to be synergistically applied with a specific auxiliary agent system for silk dyeing.
[0007] Chinese invention patent CN103451974A, published on December 18, 2013, discloses a "phase transfer catalytic color-fixing method for textiles." This technology employs the principle of phase transfer catalysis, transferring ionic alkaline substances, such as NaOH and Na2CO3, from the aqueous phase to the hydrophobic supercritical CO2 phase via a phase transfer catalyst (quaternary ammonium salt) in a supercritical CO2 fluid. These substances interact with functional groups on the fiber, enhancing their nucleophilic reactivity with the reactive groups of the dye, thereby achieving the color-fixing reaction of disperse reactive dyes on natural fibers. The color-fixing efficiency can reach over 92.4%. This method solves for the first time the problem of not being able to use ionic color-fixing accelerators in hydrophobic CO2 media, and has significant theoretical and practical value. However, this technology still has the following limitations: First, it relies on phase transfer catalysts to introduce alkaline substances from the external aqueous phase into the CO2 system, which increases the types of auxiliaries and the complexity of the process; Second, the amount of alkaline substances introduced and the release rate are difficult to control precisely, and the fixed dye may be easily hydrolyzed due to excessive alkalinity; Third, this technology is also mainly aimed at cotton fibers. Although it is mentioned that it can be applied to silk, it does not specifically optimize the process for the heat sensitivity and protein structure characteristics of silk; Fourth, it does not involve the removal of floating dye and the control of pressure reduction process after dyeing, which may affect the quality of the final product.
[0008] In summary, the following technical challenges remain unresolved in the application of existing supercritical CO2 dyeing technology to silk fabrics: (1) How to achieve high solubility of disperse dyes in supercritical CO2 at low temperatures below 80℃ to avoid thermal damage to silk; (2) How to enhance the binding force between dyes and polar silk fibers in a non-polar CO2 medium to improve color fastness; (3) How to achieve integrated dyeing and fixing in the same bath to simplify the process and improve production efficiency; (4) How to construct a synergistic technology system integrating "dye-auxiliary agent-process-medium" to form a complete waterless dyeing solution for silk fabrics.
[0009] To address the aforementioned technical problems, this invention provides a composition for supercritical carbon dioxide fluid anhydrous dyes, a dyeing process, and its application in silk fabrics. Through the synergistic design of dual-reactive dyes, tertiary amine fixing catalysts, and methyl salicylate, combined with pretreatment liquid carry-over rate control, ternary compound entrainer, in-situ pH self-adjustment, online cleaning, and graded pressure reduction, highly efficient anhydrous dyeing of silk fabrics is achieved at low temperatures of 65-75℃. Furthermore, the dyed fabric retains ≥98% of its strength and has a low yellowing index. The color fastness reaches level 4-5, demonstrating outstanding substantial characteristics and significant progress. Summary of the Invention
[0010] This invention aims to overcome the shortcomings of existing technologies and provide a composition, dyeing process, and application of supercritical carbon dioxide fluid anhydrous dyes in silk fabrics, thereby solving the problems of existing supercritical... CO2 dyeing technology has several technical problems in its application to silk fabrics, including low dyeing rate at low temperatures, poor color fastness, complex process flow, and inability to achieve dyeing and color fixing in the same bath.
[0011] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a composition for anhydrous dyes using supercritical carbon dioxide fluid, comprising the following components: Bis-reactive group modified disperse dyes, tertiary amine solid color catalysts, and methyl salicylate; The dual-reactive-group modified disperse dye contains a hydrophobic backbone and at least two reactive groups selected from vinyl sulfone group and triazine group in its molecular structure. The mass ratio of the tertiary amine-based fixing catalyst to the dual-active-group modified disperse dye is 0.1-0.5:1; The methyl salicylate, as an entrainer component, when mixed with supercritical carbon dioxide fluid, can simultaneously improve the solubility of the dual-reactive-group modified disperse dye in supercritical carbon dioxide at a dyeing temperature of 60-80℃, and hydrolyze to produce salicylic acid in the presence of trace amounts of water. The salicylic acid forms an acid-base buffer pair with the tertiary amine fixing catalyst, maintaining the pH value of the dyeing system at 7.5-8.5, thereby catalyzing the reaction between the active groups and silk fibers.
[0012] The above composition produced an unexpected synergistic effect: Those skilled in the art generally believe that acid and alkali auxiliaries should be avoided as much as possible in supercritical CO2 dyeing to prevent affecting fluid stability and equipment corrosion resistance. This invention is the first to discover that methyl salicylate and tertiary amine fixing catalysts can form a "weak acid-weak base" buffer pair in situ during the dyeing process, spontaneously stabilizing the pH value within the optimal reaction range of 7.5-8.5 without the need for external acid or alkali additions or phase transfer catalysts. Prior art document 2 (CN103451974A) requires the use of quaternary ammonium salts to transfer alkaline substances from the aqueous phase to the CO2 phase, resulting in a complex process and difficulty in controlling the alkalinity. The "in-situ self-regulating" mechanism of this invention simplifies the process and avoids the risk of bond breakage and hydrolysis of the fixed dye due to excessive alkalinity. This "ester-amine" synergistic effect was unforeseen by those skilled in the art.
[0013] Furthermore, the tertiary amine-based color-fixing catalyst is selected from at least one of octadecylamine, hexadecylamine, or tetradecylamine.
[0014] Furthermore, the dual-reactive-group modified disperse dye has the molecular structure shown in formula (I): D(-NH-XY)2; Wherein, D is an azobenzene or anthraquinone chromophore, X is a C1-C6 alkylene linker or direct bond, and Y is an active group selected from vinyl sulfone, chlorotriazine, or fluorotriazine. The two -NH-XY groups may be the same or different.
[0015] Furthermore, the composition also includes a nano-silica dispersant, wherein the mass ratio of the nano-silica to the dual-reactive-group modified disperse dye is 0.01-0.1:1.
[0016] The synergistic effect of the above-mentioned preferred technical solutions: The combined use of long-chain tertiary amines (C14-C18) and nano-silica has two advantages: firstly, the long-chain tertiary amines exhibit better solubility and affinity for silk fibers in supercritical CO2; secondly, nano-silica acts as a dispersant to prevent dye aggregation at low temperatures. This synergistic effect significantly improves dyeing uniformity, with a color difference ΔE < 0.5, superior to the effect of using either auxiliary agent alone.
[0017] In a second aspect, the present invention provides a supercritical carbon dioxide fluid anhydrous dyeing process using the above-mentioned composition, comprising the following steps: (1) Pretreatment steps: Immerse the silk fabric in deionized water, control the liquid content of the fabric to 100-150%, so that the silk fibers swell appropriately, and at the same time provide the required trace amount of water for the subsequent hydrolysis of methyl salicylate; The aforementioned pretreatment steps produced an unexpected synergistic effect: Those skilled in the art generally believe that supercritical CO2 dyeing should avoid the presence of water as much as possible to prevent disruption of the CO2 fluid's continuity. This invention takes the opposite approach, transforming "water" from an "impurity" into a "functional component." By precisely controlling the liquid carryover rate within the critical range of 100-150%, the fiber is precisely "swelled on the surface and slightly moistened internally," opening channels in the amorphous region to promote dye diffusion without compromising the stability of the CO2 fluid. More importantly, this "controllable trace water" becomes a precise water source for subsequent methyl salicylate hydrolysis, achieving "dual use of water." Comparative Example 6 shows that the fixation rate without pretreatment is only 58.4%, while Example 1 reaches 93.5%, an increase of 35.1 percentage points. This dual role of "trace water" is something those skilled in the art could not have foreseen.
[0018] (2) Entrainer compounding steps: Methyl salicylate, anhydrous ethanol, and deionized water are mixed in a volume ratio of 40-60:30-40:10-20 to prepare a compound entrainer; The aforementioned compound entrainer produced an unexpected synergistic effect: in the ternary compound system, methyl salicylate acts as a "molecular bridge," with its ester groups forming π-π stacking with the dye, and the benzene ring forming hydrogen bonds with silk; ethanol lowers the critical temperature of CO2 and improves fluid polarity; water and the entrained liquid from step (1) together constitute the "raw material library" for the hydrolysis reaction. The three components work synergistically in a specific ratio, enabling the dye to achieve a solubility of over 95% at a low temperature of 70℃, comparable to the solubility at 100℃. The dyeing rate of Comparative Example 3 (without entrainer) was only 32.5%, the dyeing rate of Comparative Example 4 (ethanol only) was 78.3%, while the dyeing rate of Example 1 (ternary compound) reached 96.8%, demonstrating a synergistic effect of 1+1+1>3.
[0019] (3) Dyeing steps: Place the pretreated silk fabric in a dyeing kettle, introduce supercritical carbon dioxide fluid, and simultaneously inject the composition and the compound entrainer. Control the dyeing temperature to 65-75℃ and the dyeing pressure to 22-28MPa. Circulate the dyeing for 40-60 minutes. During the dyeing process, the trace amount of water introduced in step (1) and the methyl salicylate introduced in step (2) undergo in-situ hydrolysis to generate salicylic acid. The salicylic acid forms an acid-base buffer pair with the tertiary amine fixing catalyst in the composition, which self-regulates and maintains the pH of the dyeing system at 7.5-8.5. At the same time, it catalyzes the covalent bonding reaction between the dual-active-group modified disperse dye and the silk fiber to achieve dyeing and fixing in the same bath. The above dyeing steps produced an unexpected synergistic effect: it is common knowledge in the art that "for every 10°C decrease in temperature, the chemical reaction rate decreases by about half". Under the condition of lowering the temperature by 30-40°C compared to the traditional process of 100-120°C, the present invention not only did not reduce the dyeing effect, but also achieved a better fixation rate. The fixation rate of Example 1 (70°C) was 93.5%, and the fixation rate of Comparative Example 7 (110°C) was 92.8%. The fixation rate at low temperature was higher than that at high temperature. It is believed that high temperature causes the fiber structure to shrink and the amorphous area to decrease, which hinders the diffusion of dye; tertiary amines are easily decomposed and lose their activity at high temperature. This phenomenon of "low temperature actually promotes fixation" completely violates the conventional expectations of those skilled in the art. At the same time, the "water" in step (1) and the "ester" in step (2) "meet" and hydrolyze in the dyeing step to form a pH buffer pair. This chain-like design of "cause and effect" makes the overall process effect far better than the simple sum of the effects of each step.
[0020] (4) Online cleaning steps: After dyeing, keep the temperature constant and pass pure supercritical carbon dioxide fluid through the tube at a pressure of 20-28MPa for 10-20 minutes to remove unfixed floating dye. The synergistic effect of the above online cleaning steps is as follows: maintaining a constant temperature of 65-75℃ ensures that the unfixed dye remains highly soluble in CO2, significantly improving cleaning efficiency. Simultaneously, due to the high fixation rate (>93%) in step (3), very little floating dye remains, and cleaning for 10-20 minutes achieves the effect of traditional water washing for over 30 minutes. Comparative Examples 1-2, which did not employ online cleaning, had a wet rubbing fastness of only around grade 3, while this invention achieved grade 4, demonstrating the crucial contribution of online cleaning to the final quality.
[0021] (5) Pressure reduction steps: Use a graded pressure reduction method, with each pressure reduction being 2-3 MPa and the pressure held for 2-5 minutes, to reduce the system pressure to normal pressure and remove the dyed silk fabric.
[0022] The synergistic effect of the above pressure reduction steps: graded pressure reduction allows the CO2 pressure gradient inside and outside the fiber to be released slowly, avoiding the "reverse dyeing effect" caused by rapid pressure reduction, that is, the dye that has entered the fiber is "pushed" back to the fiber surface by the rapidly expanding CO2. Comparative Examples 1-2 did not use graded pressure reduction, and although they had a certain fixation rate, their wet rubbing fastness was only about level 3; while the present invention, through graded pressure reduction, allows the dye sufficient time to rearrange and fix within the fiber, improving the wet rubbing fastness to level 4. This post-treatment step, together with the "sufficient dyeing" in step (3) and the "thorough cleaning" in step (4), forms a complete closed loop, jointly ensuring the excellent performance of the final product.
[0023] Furthermore, in the dyeing step (3), a pulsed pressurization method is adopted, with the pressure gradually increased to the target pressure in the rhythm of "pressurization 2MPa → pressure holding for 3-5 minutes → pressurization 2MPa", and the periodic density fluctuation of supercritical carbon dioxide fluid is used to promote the diffusion of dye into the fiber.
[0024] The synergistic effect of the aforementioned pulsed pressurization: Pulsed pressurization causes the CO2 fluid to produce a "breathing effect." During pressure fluctuations, the amorphous regions of the fiber periodically "open and close," promoting dye diffusion into the fiber interior. In the comparative example, constant pressure resulted in a dye penetration depth of only about 70%; while the present invention, using pulsed pressurization, achieved a dye penetration depth of over 90%, with a level of 4-5. This effect, together with the "fiber swelling" in step (1), forms a dual promoting mechanism, jointly solving the problem of difficult dye diffusion at low temperatures.
[0025] Furthermore, the amount of the compound entrainer injected in the dyeing step (3) is 2-5% of the total volume of the supercritical carbon dioxide fluid.
[0026] Furthermore, the liquid carrying rate of 100-150% in step (1) and the amount of methyl salicylate in the compound entrainer in step (2) work together to control the degree of hydrolysis of methyl salicylate during the dyeing process at 30-50%, thereby continuously and stably releasing salicylic acid and maintaining the pH value at 7.5-8.5 throughout the dyeing process.
[0027] An unexpected effect of the above-mentioned hydrolysis degree control: This invention found that when the liquid carry-over rate and the amount of entrainer are properly matched, the degree of hydrolysis of methyl salicylate can be stably controlled at 30-50%. This range can both continuously release sufficient salicylic acid to maintain pH stability and prevent drastic pH fluctuations due to excessively rapid hydrolysis. Figure 3 The results showed that the pH value remained stable at 7.5-8.5 throughout the 40-minute staining process, demonstrating excellent buffering capacity. This "pH stability throughout the process" effect cannot be achieved by adjusting the liquid carryover rate or the amount of entrainer alone.
[0028] Thirdly, the present invention provides a silk fabric dyed according to the above process, wherein the dyeing temperature of the silk fabric is 65-75℃, the breaking strength retention rate is ≥98%, the yellowing index Δb<1.5, and the finished product can be obtained directly without washing after dyeing.
[0029] The above product effects demonstrate the synergistic contribution of the process chain: the breaking strength retention rate is ≥98% and Δb<1.5, indicating that the present invention achieves "zero damage" dyeing of silk fibers at low temperatures; the finished product can be obtained directly without water washing, indicating that the online cleaning in step (4) and the graded pressure reduction in step (5) have completely removed the floating color, achieving true "waterless dyeing". These product indicators are the final manifestation of the synergistic effect of all the aforementioned technical features.
[0030] Fourthly, the present invention provides the application of the above composition or the above process in anhydrous dyeing of silk fabrics, wherein the dyed silk fabrics achieve a color fastness of 4-5 for soap washing, a color fastness of 4-5 for dry rubbing, and a color fastness of 4 for wet rubbing.
[0031] Comparison of the above application effects with prior art documents: Prior art document 1 (CN102392367B) achieves a maximum color fastness of 98.3% on cotton, but does not provide data for silk; tested on silk using the same process, the strength retention rate is only 85.3%, Δb=3.2. Prior art document 2 (CN103451974A) achieves a color fastness of 92.4% on cotton, but a strength retention rate of 86.1% on silk, Δb=2.8. This invention achieves a color fastness of 4-5 on silk, reaching or even exceeding the level of traditional water bath dyeing, while maintaining the natural quality of silk. This comprehensive and excellent effect achieved on "delicate" protein fibers is unattainable by existing technologies.
[0032] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves both low temperature and high dye uptake by using a ternary compound entrainer of methyl salicylate, ethanol, and water as a low-temperature entrainer at 65-75℃, which enables the dye solubility to reach more than 95% of the conventional high-temperature level of 100℃ and the dyeing rate to reach 96.8%.
[0033] This invention achieves "in-situ pH self-regulation" in the dyeing system. The trace amount of water introduced through pretreatment undergoes in-situ hydrolysis with methyl salicylate in the entrainer. The resulting salicylic acid forms an acid-base buffer pair with the tertiary amine color-fixing catalyst, spontaneously stabilizing the pH value in the optimal reaction range of 7.5-8.5. No external acid, base or phase transfer catalyst is required, avoiding the defect of the difficulty in accurately controlling alkaline substances in prior art 2.
[0034] This invention transforms "water" from an impurity into a functional component. The 100-150% liquid retention rate allows the fiber to swell appropriately, promoting dye diffusion, and also provides a precise water source for ester hydrolysis, achieving "one water for two uses".
[0035] This invention achieves the unexpected effect of "low temperature actually promoting color fixation". The color fixation rate at 70℃ (93.5%) is higher than that at 110℃ (92.8%), avoiding fiber shrinkage and tertiary amine decomposition caused by high temperature. At the same time, it achieves "zero damage" dyeing of silk, with a strength retention rate of ≥98% and a yellowing index Δb<1.5.
[0036] This invention employs a five-step process that forms a complete technological closed loop. The "breathing effect" of pulsed pressure promotes dye diffusion, online cleaning thoroughly removes excess dye, and graded pressure reduction prevents "reverse dyeing." The final product exhibits a colorfastness of 4-5 to soap washing and a wet rubbing resistance of 4, allowing for direct production of finished silk fabrics without the need for water washing. This truly achieves waterless and clean production of silk fabrics. Attached Figure Description
[0037] Figure 1 The flowchart of the supercritical carbon dioxide anhydrous dyeing process of this invention.
[0038] Figure 2 This is a comparison chart of the color-fixing efficiency of dyed silk fabrics in Examples 1-4 and Comparative Examples 1-4 of the present invention.
[0039] Figure 3 This is a graph showing the change in pH value over time during the staining process in Example 1 of the present invention. Detailed Implementation
[0040] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0041] It should be clarified that the "composition" and the "compound entrainer" described in this invention exist independently and are prepared separately. The "composition" contains a dual-reactive-group modified disperse dye and a tertiary amine fixing catalyst, and optionally contains a nano-silica dispersant. The "compound entrainer" is a mixture of methyl salicylate, anhydrous ethanol, and deionized water in a specific ratio. In the dyeing step, both are injected into the dyeing vessel separately or mixed. Methyl salicylate, as a key functional component, acts as an "ester" in the "composition," forming an acid-base buffer pair in situ with the tertiary amine catalyst; on the other hand, as a major component in the "compound entrainer," it synergistically enhances the solubility of the dye in supercritical carbon dioxide with ethanol. Through this "separate placement-mixing" method, precise control and maximum utilization of the functions of each component are achieved.
[0042] The raw materials used in the examples are sourced from: Bi-reactive group modified disperse dyes: can be prepared by following the method described in Chinese invention patent CN101463201A, or purchased from Yongguang Chemical Co., Ltd. in Taiwan (customization required). Octadecylamine, hexadecylamine, tetradecylamine: purchased from Aladdin Reagent (Shanghai) Co., Ltd.; Methyl salicylate and anhydrous ethanol: purchased from Sinopharm Chemical Reagent Co., Ltd. Nano-silica (particle size 20-30nm): purchased from CESI, Germany; Silk fabric: 100% mulberry silk, electric spinning, 60g / m², purchased from Zhejiang Silk Technology Co., Ltd., China.
[0043] Test method: (1) Dyeing rate determination: The residual liquid method was adopted, and the absorbance of the dye solution before and after dyeing at the maximum absorption wavelength was measured by a UV-Vis spectrophotometer, and the dyeing rate was calculated. (2) Fixation rate determination: The acetone extraction method was used, and the determination was performed according to the method described in Example CN102392367B; (3) Tensile strength retention rate: determined according to GB / T3923.1-2013 "Textiles - Tensile properties of fabrics - Part 1: Determination of tensile strength and elongation at break (strip method)"; (4) Yellowing index Δb: The b value of the fabric before and after dyeing was measured using a Hunter Lab UltraScanPRO colorimeter, and Δb was calculated. (5) Color fastness test: Color fastness to soap washing is tested according to GB / T3921-2008; Color fastness to rubbing is tested according to GB / T3920-2008; (6) pH value determination: A high-pressure window is installed in the bypass of the staining system, and the pH value is determined by a combination of pH test paper method and indicator method.
[0044] Example 1 This embodiment provides a composition for anhydrous dyes using supercritical carbon dioxide fluid and its dyeing process.
[0045] 1. Preparation of the composition The composition was prepared according to the following proportions: Bi-reactive group modified disperse dye (vinyl sulfone group + triazine group): 10g Octadecylamine: 3g (0.3:1 by weight of dye) Methyl salicylate: 20g Nano silica: 0.2g (to dye by mass ratio 0.02:1) The above components are mixed evenly in a ball mill to obtain a powdered composition, which is then sealed for later use.
[0046] 2. Preparation of compound entrainer Methyl salicylate, anhydrous ethanol, and deionized water were mixed in a volume ratio of 50:35:15 and stirred until homogeneous to obtain a compound entrainer.
[0047] 3. Dyeing process Adopting such Figure 1 The supercritical CO2 staining system shown is used for staining, and the specific steps are as follows: (1) Pretreatment: The silk fabric is immersed in deionized water, and the liquid content of the fabric is controlled to 120% by the rolling mill to make the fibers swell appropriately; (2) Loading into the dyeing vessel: Wrap the pretreated 50g silk fabric flat on the dyeing warp beam and place it in a 5L dyeing vessel; Load the 10g dye-containing composition prepared in step 1 into the dyeing vessel; (3) Entrainer injection: 150 mL of the compound entrainer prepared in step 2 (accounting for 3% of the total CO2 volume) is injected into the entrainer vessel; (4) Gentle pressure increase: Start the system, introduce CO2, and use a pulse pressure increase method: gradually increase the pressure to 25MPa in the rhythm of "increase pressure by 2MPa → hold pressure for 3 minutes → increase pressure by 2MPa", while simultaneously increasing the temperature to 70℃; (5) Circulating staining: Start the circulating pump to make the supercritical CO2 fluid circulate, with a circulation flow rate of 25L / h and a staining time of 50 minutes; During the staining process, the trace amount of water introduced in step (1) and the methyl salicylate in the entrainer undergo in-situ hydrolysis, and the generated salicylic acid forms an acid-base buffer pair with octadecylamine, maintaining the pH value of the staining system at 7.5-8.5. (6) Online cleaning: After dyeing, maintain the temperature at 70°C, close the valves of the dye tank and the entrainer tank, introduce pure supercritical CO2 fluid, and circulate and clean for 15 minutes at a pressure of 25MPa to remove unfixed floating dye. (7) Staged pressure reduction: The system pressure is gradually reduced to atmospheric pressure by reducing the pressure by 2.5 MPa each time and holding the pressure for 3 minutes. (8) Take out the dyed silk fabric: Open the dyeing kettle and take out the dyed silk fabric.
[0048] 4. Test Results The performance test results of the dyed silk fabric in this embodiment are as follows:
[0049] Example 2 This embodiment is basically the same as Example 1, except that octadecylamine is replaced with an equal amount of hexadecylamine, while other conditions remain unchanged. The test results are shown in Table 1.
[0050] Example 3 This embodiment is basically the same as Example 1, except that octadecylamine is replaced with an equal amount of tetradecylamine, while other conditions remain unchanged. The test results are shown in Table 1.
[0051] Example 4 This embodiment is basically the same as Embodiment 1, except that the pretreatment liquid carrying rate is adjusted to 100% (reduced), while other conditions remain unchanged. The test results are shown in Table 1.
[0052] Example 5 This embodiment is basically the same as Embodiment 1, except that the pretreatment liquid carrying rate is adjusted to 150% (increased), while other conditions remain unchanged. The test results are shown in Table 1.
[0053] Example 6 This embodiment is basically the same as Embodiment 1, except that the volume ratio of methyl salicylate:ethanol:water in the compound entrainer is adjusted to 40:40:20, while other conditions remain unchanged. The test results are shown in Table 1.
[0054] Example 7 This embodiment is basically the same as Example 1, except that the volume ratio of methyl salicylate:ethanol:water in the compound entrainer is adjusted to 60:30:10, while other conditions remain unchanged. The test results are shown in Table 1.
[0055] Example 8 This embodiment is basically the same as Embodiment 1, except that the staining temperature is adjusted to 65℃ (lower), while other conditions remain unchanged. The test results are shown in Table 1.
[0056] Example 9 This embodiment is basically the same as Embodiment 1, except that the staining temperature is adjusted to 75℃ (increased), while other conditions remain unchanged. The test results are shown in Table 1.
[0057] Example 10 This embodiment is basically the same as Example 1, except that no nano-silica dispersant is added, while other conditions remain unchanged. The test results are shown in Table 1.
[0058] Table 1 Summary of test results for Examples 1-10
[0059] Comparative Example 1 (Refer to Example 1 of CN102392367B) Dyeing and color fixing were performed according to the method described in Example 1 of CN102392367B: (1) Dyeing: In supercritical CO2, at 80℃ and 23MPa, disperse reactive red dye (single reactive group) was used to dye pure cotton woven fabric (humidified treatment, moisture content 100%) for 120 min; (2) Fixing: Transfer the dyed fabric to a fixing kettle and fix it for 60 min at 6.0 MPa and 140 °C with triethylenediamine as a catalyst.
[0060] The test results are shown in Table 2.
[0061] Comparative Example 2 (Refer to Example 1 of CN103451974A) Dyeing and color fixing were performed according to the method described in Example 1 of CN103451974A: (1) Dyeing: Dry pure cotton woven fabrics are dyed in supercritical CO2 using disperse reactive red dye; (2) Color fixation: A phase transfer catalytic color fixation device was used at 20 MPa and 100 °C. A mixed solution of Na2CO3 and FC-134 was used as a color-fixing accelerator, and the color was fixed for 60 minutes.
[0062] The test results are shown in Table 2.
[0063] Comparative Example 3 (without encapsulant) This comparative example is basically the same as Example 1, except that no entrainer was added (no methyl salicylate, ethanol, or water), and other conditions remained unchanged. The test results are shown in Table 2.
[0064] Comparative Example 4 (without methyl salicylate) This comparative example is basically the same as Example 1, except that the entrainer is only anhydrous ethanol (without methyl salicylate and water), and other conditions remain unchanged. The test results are shown in Table 2.
[0065] Comparative Example 5 (without tertiary amine fixing agent) This comparative example is basically the same as Example 1, except that octadecylamine is not added to the composition, while other conditions remain unchanged. The test results are shown in Table 2.
[0066] Comparative Example 6 (without pretreatment and containing liquid) This comparative example is basically the same as Example 1, except that the silk fabric is not pretreated (dry state), and other conditions remain unchanged. The test results are shown in Table 2.
[0067] Comparative Example 7 (High-Temperature Staining) This comparative example is basically the same as Example 1, except that the dyeing temperature is increased to 110℃ (the traditional polyester dyeing temperature), while other conditions remain unchanged. The test results are shown in Table 2.
[0068] Table 2 Summary of test results for comparative examples 1-7
[0069] Table 2 Note: ¹The original dyeing material for Comparative Examples 1-2 was cotton, and the dyeing rate data in the table are the results on cotton. To evaluate its applicability to silk, this application applied the complete process conditions of Prior Art Documents 1 and 2 to the same silk fabric as this invention, and measured its strength retention rate and yellowing index. (Δb) are shown in the table below.
[0070] Results Analysis The test results in Tables 1 and 2 show that: (1) Compared with Comparative Examples 1-2, the color fixation rate of Example 1 of the present invention on silk fabric (93.5%) is comparable to that of Comparative Example 2 on cotton (92.4%). More importantly, when the processes of Comparative Examples 1 and 2 are applied to silk, the strength retention rate drops sharply to 85.3% and 86.1%, respectively, and the yellowing index is as high as 3.2 and 2.8. In contrast, the present invention, dyed under mild conditions of 70°C, achieves a strength retention rate as high as 98.7% and a yellowing index of only 1.2, fully demonstrating the significant and incomparable advantages of the present invention in protecting silk fibers.
[0071] (2) Compared with Comparative Example 3 (without entrainer), the dyeing rate and fixation rate of Example 1 of the present invention increased by 64.3 and 64.8 percentage points, respectively, indicating that the entrainer is crucial for low-temperature dyeing.
[0072] (3) Compared with Comparative Example 4 (without methyl salicylate), the dyeing rate and fixation rate of Example 1 of the present invention increased by 18.5 and 21.4 percentage points, respectively, indicating that the introduction of methyl salicylate significantly improved the dyeing effect.
[0073] (4) Compared with Comparative Example 5 (without tertiary amine color-fixing catalyst), the color-fixing rate of Example 1 of the present invention increased by 17.3 percentage points, indicating that the catalytic effect of tertiary amine color-fixing catalyst is crucial to improving the color-fixing rate.
[0074] (5) Compared with Comparative Example 6 (without pretreatment solution), the dyeing rate and fixation rate of Example 1 of the present invention increased by 28.1 and 35.1 percentage points, respectively, indicating that the pretreatment solution has a significant promoting effect on low temperature dyeing.
[0075] (6) Compared with Comparative Example 7 (high temperature dyeing), Example 1 of the present invention maintains similar dyeing rate and fixation rate, while increasing strength retention rate by 16.4 percentage points and reducing yellowing index by 3.3, indicating that the present invention achieves high temperature dyeing effect at low temperature while avoiding fiber damage.
[0076] Example 11: Monitoring pH changes during staining In this embodiment, during the staining process of Example 1, the pH value change of the system was monitored in real time through a bypass high-pressure viewing window. The results are as follows: Figure 3 As shown.
[0077] from Figure 3 It can be seen that: in the initial stage of staining (0-10 minutes), the pH value of the system gradually increased from 7.0 to 7.5; in the middle stage of staining (10-40 minutes), the pH value remained stable between 7.5 and 8.5; in the later stage of staining (40-50 minutes), the pH value decreased slightly but remained above 7.5. This indicates that methyl salicylate and octadecylamine formed an effective acid-base buffer pair, achieving pH self-regulation throughout the staining process.
[0078] Example 12: Industrial-scale scale-up test This embodiment involves a scale-up experiment conducted on a 50L industrial-scale supercritical CO2 dyeing equipment. 5 kg of silk fabric was taken and dyed according to the process described in Example 1. The performance test results of the dyed fabric are as follows:
[0079] The results show that the technical solution of the present invention has good applicability on industrial-scale equipment as well, and the staining effect is basically consistent with the results of the small-scale test.
[0080] Industrial applicability The composition, dyeing process, and application provided by this invention can be widely used in the anhydrous dyeing production of silk fabrics. Compared with the prior art, this invention has the following advantages in industrial applicability: (1) Simplified process flow: It realizes the integration of dyeing and fixing in the same bath, without the need for step-by-step processing as in Comparative Document 1, and increases production efficiency by more than 30%. (2) Reduced equipment requirements: No need for low-pressure color-fixing kettle or phase transfer catalytic device, reducing equipment investment by more than 20%; (3) Significant energy conservation and emission reduction: No water is used throughout the process, CO2 recycling rate is >95%, and there is no wastewater discharge; (4) Excellent product quality: The dyed silk fabric has high strength retention and good color fastness, meeting the requirements of the high-end market; (5) Strong process controllability: The pH self-regulation mechanism avoids fluctuations caused by external acids and alkalis, and the dyeing reproducibility is good, making it suitable for industrial production.
[0081] Therefore, this invention has extremely high industrial practical value and broad application prospects.
[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A composition for anhydrous dyes using supercritical carbon dioxide fluid, characterized in that, Includes the following components: Bis-reactive group modified disperse dyes, tertiary amine solid color catalysts, and methyl salicylate; The dual-reactive-group modified disperse dye contains a hydrophobic backbone and at least two reactive groups selected from vinyl sulfone group and triazine group in its molecular structure. The mass ratio of the tertiary amine-based fixing catalyst to the dual-active-group modified disperse dye is 0.1-0.5:1; The methyl salicylate, as an entrainer component, when mixed with supercritical carbon dioxide fluid, can simultaneously improve the solubility of the dual-reactive-group modified disperse dye in supercritical carbon dioxide at a dyeing temperature of 60-80℃, and hydrolyze to produce salicylic acid in the presence of trace amounts of water. The salicylic acid forms an acid-base buffer pair with the tertiary amine fixing catalyst, maintaining the pH value of the dyeing system at 7.5-8.5, thereby catalyzing the reaction between the active groups and silk fibers.
2. The composition according to claim 1, characterized in that, The tertiary amine-based color-fixing catalyst is selected from at least one of octadecylamine, hexadecylamine, or tetradecylamine.
3. The composition according to claim 1, characterized in that, The dual-reactive-group modified disperse dye has the molecular structure shown in formula (I): D(-NH-XY)2; Wherein, D is an azobenzene or anthraquinone chromophore, X is a C1-C6 alkylene linker or direct bond, and Y is an active group selected from vinyl sulfone, chlorotriazine, or fluorotriazine. The two -NH-XY groups may be the same or different.
4. The composition according to claim 1, characterized in that, The composition further comprises a nano-silica dispersant, wherein the mass ratio of the nano-silica to the dual-reactive-group modified disperse dye is 0.01-0.1:
1.
5. A supercritical carbon dioxide fluid anhydrous dyeing process using the composition according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Pretreatment steps: Immerse the silk fabric in deionized water, control the liquid content of the fabric to 100-150%, so that the silk fibers swell appropriately, and at the same time provide the required trace amount of water for the subsequent hydrolysis of methyl salicylate; (2) Entrainer compounding steps: Methyl salicylate, anhydrous ethanol, and deionized water are mixed in a volume ratio of 40-60:30-40:10-20 to prepare a compound entrainer; (3) Dyeing steps: Place the pretreated silk fabric in a dyeing kettle, introduce supercritical carbon dioxide fluid, and simultaneously inject the composition and the compound entrainer. Control the dyeing temperature to 65-75℃ and the dyeing pressure to 22-28MPa. Circulate the dyeing for 40-60 minutes. During the dyeing process, the trace amount of water introduced in step (1) and the methyl salicylate introduced in step (2) undergo in-situ hydrolysis to generate salicylic acid. The salicylic acid forms an acid-base buffer pair with the tertiary amine fixing catalyst in the composition, which self-regulates and maintains the pH of the dyeing system at 7.5-8.
5. At the same time, it catalyzes the covalent bonding reaction between the dual-active-group modified disperse dye and the silk fiber to achieve dyeing and fixing in the same bath. (4) Online cleaning steps: After dyeing, keep the temperature constant and pass pure supercritical carbon dioxide fluid through the tube at a pressure of 20-28MPa for 10-20 minutes to remove unfixed floating dye. (5) Pressure reduction steps: Use a graded pressure reduction method, with each pressure reduction being 2-3 MPa and the pressure held for 2-5 minutes, to reduce the system pressure to normal pressure and remove the dyed silk fabric.
6. The process according to claim 5, characterized in that, In the dyeing step (3), a pulsed pressure increase method is adopted, with the pressure gradually increased to the target pressure in the rhythm of "increase pressure by 2MPa → hold pressure for 3-5 minutes → increase pressure by 2MPa", and the periodic density fluctuation of supercritical carbon dioxide fluid is used to promote the diffusion of dye into the fiber.
7. The process according to claim 5, characterized in that, The amount of the compound entrainer injected in the dyeing step (3) is 2-5% of the total volume of the supercritical carbon dioxide fluid.
8. The process according to claim 5, characterized in that, The liquid carrying rate of 100-150% in step (1) and the amount of methyl salicylate in the compound entrainer in step (2) work together to control the degree of hydrolysis of methyl salicylate during the dyeing process at 30-50%, thereby continuously and stably releasing salicylic acid and maintaining the pH value at 7.5-8.5 throughout the dyeing process.
9. A silk fabric dyed according to any one of claims 5-8, characterized in that, The dyeing temperature of the silk fabric is 65-75℃, the breaking strength retention rate is ≥98%, and the yellowing index is... Furthermore, the finished product can be obtained directly without washing after dyeing.
10. The application of the composition according to any one of claims 1-4 or the process according to any one of claims 5-8 in anhydrous dyeing of silk fabrics, characterized in that, The dyed silk fabric exhibits a color fastness of 4-5 for soap washing, 4-5 for dry rubbing, and 4 for wet rubbing.