High-color-fastness gambiered canton gauze dyeing method

Abstract

The invention provides a high-color-fastness gambiered canton gauze dyeing method which comprises the following steps: soaking a gambiered canton gauze coarse fabric in a 0.5-1% polycarboxylic acid buffer solution at 40-50 DEG C for 30 minutes, and airing at normal temperature to obtain a silk fabric; heating the rhizoma dioscoreae cirrhosae extracting solution to 80-100 DEG C, adjusting the pH value to 5.5-6.0, putting the silk fabric into the rhizoma dioscoreae cirrhosae extracting solution, and maintaining the temperature for 60 minutes to obtain a dyed fabric; placing the dyed fabric in a 0.5-1% polyphenol chelating solution, heating the dyed fabric to 50-60 DEG C, maintaining the temperature for 20-30 minutes, taking out the dyed fabric, spin-drying the dyed fabric, placing the dyed fabric in a 1-1.5% tea polyphenol solution, heating the dyed fabric to 50-60 DEG C, maintaining the temperature for 20-30 minutes, finally immersing the dyed fabric in a composite mordant dyeing solution, heating the dyed fabric to 40-50 DEG C, and maintaining the temperature for 10 minutes to obtain a pretreated fabric; the pretreated fabric is evenly coated with the reddish brown mud coating slurry, solarization is carried out, cleaning and airing are carried out, and gambiered canton gauze is obtained after shaping. Therefore, the problem that the traditional gambiered canton gauze is easy to fade is effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of fabric processing, and in particular relates to a method for dyeing Xiangyun yarn with high color fastness. Background Art

[0002] Xiangyunsha (also known as Yunjinsha) is a traditional silk fabric originating from Guangdong, China, renowned for its unique wrinkle-like effect and soft, cloud-like sheen. Its key craftsmanship features a base of mulberry silk, employing either plain or double crepe weaves to preserve the toughness and luster of the silk fibroin. Traditionally, the fabric is dyed using natural tannin extracts from persimmon peel, yam, or gallnut. After dyeing, it is coated with iron-oxide-rich river mud (reddish-brown mud). Sun-oxidized, the iron ions in the mud combine with the dye to form a complexing layer, which is then washed clean, revealing the unique cloud pattern and wrinkle-like sheen.

[0003] The traditional process mainly relies on physical adsorption and complexation with iron ions in red-brown mud. It lacks the deep fixation of chemical covalent bonds or strong coordination bonds. Most of the dye molecules remain on the surface of the fiber and are easily dissociated and carried away by water or friction, resulting in discoloration. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for dyeing Xiangyunsha with high color fastness, aiming to solve the problem that Xiangyunsha is easy to fade.

[0005] To solve the above technical problems, the present invention is implemented as follows: a method for dyeing Xiangyun yarn with high color fastness is proposed, comprising the following steps: S1. Soaking a coarse Xiangyunsha fabric in 0.5-1% polycarboxylic acid buffer at 40-50° C. for 30 minutes and drying it at room temperature to obtain a silk fabric; S2, heating the Dioscorea scoparia extract to 80-100° C., adjusting the pH to 5.5-6.0, placing the silk fabric into the Dioscorea scoparia extract, and maintaining the temperature for 60 minutes to obtain a dyed fabric; S3, placing the dyed fabric in a 0.5-1% polyphenol chelating solution, heating it to 50-60°C for 20-30 minutes, taking it out and drying it, then placing it in a 1-1.5% tea polyphenol solution, heating it to 50-60°C for 20-30 minutes, and finally immersing it in a composite mordant solution, heating it to 40-50°C for 10 minutes to obtain a pretreated fabric; S4. Evenly apply red-brown mud coating slurry to the pretreated fabric, expose it to the sun, then wash and dry it, and obtain Xiangyunsha after shaping.

[0006] In some embodiments, in step S1, the polycarboxylic acid buffer comprises at least one of a citric acid buffer, an oxalic acid buffer, a tartaric acid buffer, a maleic acid buffer, and a succinic acid buffer.

[0007] In some embodiments, step S1 includes: S1.1. Completely immerse the coarse Xiangyunsha fabric in a 0.5-1% polycarboxylic acid buffer solution preheated at 40-50°C. The ratio of polycarboxylic acid buffer to the coarse Xiangyunsha fabric should be controlled at 20:1. Soak for 30 minutes, stirring regularly. S1.2. Rinse the fabric with deionized water three times, each time for 5 minutes, until the pH of the cleaning solution reaches 5.0±0.3. After cleaning, dry the fabric naturally at room temperature to obtain a silk fabric.

[0008] In some embodiments, step S2 includes: S2.1. Weigh radix serrata powder and add it to deionized water. Heat to 90-95°C and stir at this temperature for 1 hour. Then filter through a 300-mesh nylon cloth to obtain a clear brown-red dye solution. S2.2. Adjust the pH of the clarified brown-red dye solution to 5.5-6.0 using diluted citric acid buffer or lactic acid buffer. S2.3. Heat the clarified brownish-red dye solution to 80-100°C. After the temperature stabilizes, lay the silk fabric flat on the clarified brownish-red dye solution. The liquid-to-material ratio of the clarified brownish-red dye solution to the silk fabric should be controlled at (20-30):1. S2.4. Maintain the temperature at 80-90°C, immerse for 10 minutes, then remove from the dye and allow to stand in the air for natural oxidation for 10 minutes. S2.5. Repeat step S2.4 for 3 to 5 rounds, with the total time controlled within 60 minutes. After dyeing, cool naturally to 40°C, then use 40°C deionized warm water to soak 3 times, and ventilate and dry in the shade to obtain the dyed fabric.

[0009] In some embodiments, in step S3, the polyphenol chelating solution includes at least one of a water-soluble tannin iron complex solution, a gallic acid solution, and an acorn tannic acid solution.

[0010] In some embodiments, in step S3, the composite mordant solution includes an aluminum source, a zirconium source, and a titanium source, the aluminum source includes at least one of aluminum chloride, aluminum sulfate, and aluminum acetate, the zirconium source includes at least one of zirconium oxychloride, zirconium sulfate, and zirconium acetate, and the titanium source includes at least one of titanium tetrachloride, potassium titanate, and titanium citrate complex.

[0011] In some embodiments, step S3 includes: S3.1. Add 0.5-1% polyphenol chelate solution to the dye bucket, heat to 50-60°C, add the dyed fabric, and control the liquid-to-material ratio of polyphenol chelate solution to dyed fabric to be 20:1. Soak for 20-30 minutes while stirring. Remove from the dye bucket and spin dry after soaking. S3.2. Immerse the dried dyed fabric in a preheated tea polyphenol solution at 50-60°C for 20-30 minutes, then allow to cool naturally after treatment. S3.3. Place the cooled dyed fabric into the composite mordant solution, heat it to 40-50°C, maintain the treatment for 10 minutes, take it out after the treatment, rinse it with clean water 1-2 times, and dry it to obtain the pretreated fabric.

[0012] In some embodiments, step S4 includes: S4.1. Add deionized water to the mud material in a mass ratio of 1:3, stir and disperse for 20 minutes, filter through a 200-mesh sieve, and let it stand for degassing for 1 hour to obtain a red-brown mud coating slurry; S4.2. Lay the pretreated fabric flat under a scraper and apply the red-brown mud coating slurry 1 to 2 times with controlled thickness. Let it stand for 10 minutes after application to obtain a mud fabric composition. S4.3. Hang the mud-fabric combination on a drying rack for sun exposure, turning it over every 2-3 hours during the exposure period. During the non-sun exposure period, use a combination of 365 nm wavelength and visible light lamps for additional sun exposure for 12-18 hours. S4.4. After exposure to the sun, place the mud fabric composition in water at 35-40°C, stir for 10 minutes, and repeat rinsing 2-3 times until the washing water is no longer obviously turbid. After drying in the shade, use hot air drying at 90-100°C, and then press and shape for 3-5 minutes to obtain Xiangyunsha.

[0013] Compared with the prior art, the high color fastness Xiangyun yarn dyeing method of the present invention has the following beneficial effects: Polycarboxylic acids hydrolyze or swell sericin under weak acid conditions, removing surface colloids while simultaneously chelating soluble metal ions, preventing them from catalyzing dye precipitation or fiber damage during subsequent dyeing. High-temperature dyeing enhances the thermal motion of dye molecules, accelerating their diffusion and penetration within the microporous structure, allowing the quinone and flavonoid dyes in the dioscorea root to penetrate deeply into the fiber. The polyphenol chelating layer initially forms a thin film with the dye and silk fibroin through hydrogen bonding, π-π stacking, and multidentate chelation of metal ions, securing the primary polymer. The tea polyphenol reinforcement layer further embeds itself within the micropores, providing antioxidant and UV protection against dye degradation. It also crosslinks with the polyphenol chelating layer, thickening the fixed film. The three metal ions in the composite mordant simultaneously coordinate with the phenolic hydroxyl, carbonyl, and amino groups on the polyphenols and the fiber, forming a dual network of chemical coordination bonds and physical crosslinks that secure the dye molecules to the fiber surface and interior, significantly improving resistance to washing, perspiration, abrasion, and light. The iron ions in the red brown mud combine with the polyphenol chelate layer and the dye to form a water-insoluble iron-phenol-dye complex that cannot be washed out. This effectively solves the problem of traditional Xiangyunsha being easily discolored. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1The present invention is a schematic diagram of a method for dyeing Xiangyun yarn with high color fastness in one embodiment of the present invention. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] Please refer to Figure 1 The present invention provides a method for dyeing Xiangyun yarn with high color fastness, the steps comprising: S1. Soak the Xiangyunsha coarse fabric in 0.5-1% polycarboxylic acid buffer at 40-50°C for 30 minutes and air-dry at room temperature to obtain a silk fabric.

[0017] In step S1, the polycarboxylic acid buffer includes at least one of a citric acid buffer, an oxalic acid buffer, a tartaric acid buffer, a maleic acid buffer, and a succinic acid buffer.

[0018] Step S1 includes: S1.1. Completely immerse the coarse Xiangyunsha fabric in a 0.5-1% polycarboxylic acid buffer solution preheated at 40-50°C. The ratio of polycarboxylic acid buffer to the coarse Xiangyunsha fabric should be controlled at 20:1. Soak for 30 minutes, stirring regularly. The selected polycarboxylic acids (such as citric acid, tartaric acid, oxalic acid, maleic acid, and succinic acid) all contain 2–3 -COOH groups, providing excellent buffering capacity in the acidic region and maintaining a constant pH in the soaking solution. By hydrolyzing or swelling the sericin in Xiangyunsha coarse fabric under weakly acidic conditions (pH ≈ 4.5–5.5), the surface colloid content is reduced, exposing more hydroxyl and amino sites on the silk fibroin for dye binding. This stabilizes the fiber surface pH within the 4.5–5.5 range, making it compatible with subsequent safflower dyeing and preventing uneven dye development or precipitation caused by pH fluctuations. The polycarboxylic acids form complexes with soluble metal ions on the silk surface, removing metal impurities that could potentially catalyze dye oxidation or damage the fiber, facilitating uniform and stable subsequent dyeing.

[0019] Citric acid has three carboxyl groups and a large coordination constant, allowing it to form multidentate chelates with both metal ions and fiber hydroxyl groups. Oxalic acid, with its dicarboxyl groups and compact structure, offers a fast complexation rate, making it superior to metal ion removal under strongly acidic conditions. Tartaric acid, with its dicarboxyl glycol, combines chelation with hydrogen bonding. Maleic and succinic acids, with their dicarboxyl groups, can fine-tune the density of carboxyl groups on the fiber surface and the rigidity of the complexation network, optimizing the hydrophilic / hydrophobic balance. Temperatures between 40 and 50°C can accelerate the weak esterification or hydrolysis of carboxylic acids with sericin without excessively disrupting the silk secondary structure.

[0020] S1.2. Rinse the fabric with deionized water three times, each time for 5 minutes, until the pH of the cleaning solution reaches 5.0±0.3. After cleaning, dry the fabric naturally at room temperature to obtain a silk fabric.

[0021] Three 5-minute rinses eliminate free polycarboxylic acids, dissolved sericin fragments, and complexes, preventing acidic or impurity interference during subsequent dyeing. pH measurement ensures that the fiber surface is free of excessive acid residue, maintaining a baseline pH for subsequent dyeing and improving the consistency of dye liquor-fiber affinity. Air-drying at room temperature prevents excessive shrinkage or denaturation of the silk fibroin, preserving the yarn's soft feel and crinkle-like properties. Deionized water, without additional ion competition, efficiently removes low-molecular-weight acids and complexed metal ions adsorbed on the fiber surface, restoring the fiber to a near-neutral environment. After each rinse, measure the rinse solution pH until it reaches 5.0±0.3 to avoid pH shifts caused by insufficient buffering or excessive soaking. Slowly remove water to prevent rapid fiber warping or fibroin chain breakage, laying a good physical foundation for subsequent dyeing and the formation of the fixing layer.

[0022] S2. Heat the Dioscorea scoparia extract to 80-100° C., adjust the pH to 5.5-6.0, put the silk fabric into the Dioscorea scoparia extract, maintain the temperature for 60 minutes, and obtain a dyed fabric.

[0023] Step S2 includes: S2.1. Weigh Dioscorea scoparia powder and add it to deionized water. Heat to 90-95°C. Stir at this constant temperature for 1 hour. Filter through a 300-mesh nylon cloth to obtain a clear brown-red dye solution.

[0024] At a constant temperature of 90-95°C, quinones (such as emodin and hyoscyamine) and flavonoids in Dioscorea scoparia are fully dissolved, with extraction yields exceeding 85%. Filtering through a 300-mesh nylon cloth retains particles larger than 50μm, resulting in a clear dye solution and preventing subsequent uneven coloring and scumming on the fabric surface. Increasing the temperature disrupts plant cell walls and accelerates the diffusion of dye components into the aqueous phase. The primary active ingredients in Dioscorea scoparia are emodin and its aglycone, which have a 1,4-dicarbonyl structure and are readily soluble in hot water. Physical retention removes cellulose debris and fine sand, improving dye uniformity.

[0025] In one embodiment, a natural deep co-solvent is added to the clear brown-red dye solution. The natural deep co-solvent can be at least one of choline chloride and glycerol, choline chloride and lactic acid, choline chloride and malic acid, betaine and glycerol, or choline chloride and disodium citrate. The specific volume ratios are as follows: Choline chloride: glycerol (1:2), glycerol is a natural triol, which forms a low melting point, high solubility liquid phase system with choline chloride; it has good solubility and penetration ability for polyphenols, quinone dyes and silk fibroin.

[0026] Choline chloride: lactic acid (1:2). Lactic acid is a natural α-hydroxy acid that, when combined with choline, provides a stronger acidic dissolution environment. Its lower viscosity facilitates heat transfer in high-temperature dyeing systems. Choline chloride: malic acid (1:1). Malic acid contains two carboxyl groups, which increase fiber surface hydrophilicity and metal ion chelation. It promotes uniform dye distribution and enhances fiber penetration during dyeing. Betaine: glycerol (1:2). Betaine (a natural amino acid derivative) and glycerol are both non-toxic and environmentally friendly, promoting the dissolution and fixation of natural dyes. Choline chloride: disodium citrate (1:1). The sodium salt of citric acid increases the pH buffer range of the system, balancing acidic dissolution with weak alkaline stability, which is beneficial for pH-sensitive dye systems.

[0027] S2.2. Adjust the pH of the clarified brown-red dye solution to 5.5-6.0 using diluted citric acid buffer or lactic acid buffer.

[0028] Controlling the pH between 5.5 and 6.0 inhibits excessive oxidation, polymerization, or precipitation of quinone dyes, maintaining dye activity. The hydroxyl and amine groups in silk fabrics carry a slight positive charge in a slightly acidic environment, which facilitates electrostatic adsorption with negatively charged dye molecules. Citric acid buffering, a tricarboxylic acid system, covers a buffering range of 5.5–6.0. Lactic acid buffering, a monohydroxy monocarboxylic acid, can raise the pH to 5.5–6.0 when combined with sodium lactate. This is gentle on silk fabrics and is crucial for maintaining the pH of the dye bath, preventing pH fluctuations caused by the addition of acid or alkali.

[0029] S2.3. Heat the clear brown-red dye solution to 80-100°C. After the temperature stabilizes, lay the silk fabric flat on the clear brown-red dye solution. The liquid-to-material ratio of the clear brown-red dye solution to the silk fabric should be controlled at (20-30):1.

[0030] Temperatures of 80–100°C reduce dye liquor viscosity, enhancing dye diffusion and penetration into fiber micropores. High temperatures enhance molecular thermal motion, promoting hydrogen bonding, van der Waals forces, and trace covalent interactions between dye molecules and silk fibroin. At high temperatures, –OH (phenolic hydroxyl) and –C=O (quinone carbonyl) groups more readily form weak covalent or hydrogen bonds with amino groups on the fabric surface. The optimal liquid-to-solid ratio ensures full fiber penetration without wasting dye liquor.

[0031] S2.4. Maintain the temperature at 80~90℃, soak for 10 minutes, then take out and place in the air for natural oxidation for 10 minutes.

[0032] A short 10-minute heating and impregnation process completes initial adsorption, followed by a 10-minute natural oxidation process to generate a highly polymerized medium, preventing excessive precipitation of the dye all at once. The multi-round oxidation process allows the dye to polymerize layer by layer on the fiber, forming insoluble macromolecules that enhance washability and abrasion resistance. The emodin in Dioscorea paniculates easily in air to form polymers, which can form a network-like structure on the fiber surface. Oxidation is performed at 80–90°C. Excessively high temperatures can damage the fiber, while too low temperatures can result in an insufficient oxidation rate.

[0033] S2.5. Repeat step S2.4 for 3 to 5 rounds, with the total time controlled within 60 minutes. After dyeing, cool naturally to 40°C, then use 40°C deionized warm water to soak 3 times, and ventilate and dry in the shade to obtain the dyed fabric.

[0034] 3–5 cycles of dyeing achieve cumulative color depth, avoiding color differences or dye blockage caused by surface accumulation due to excessive dyeing in one go. Three rinses in 40°C warm water remove unfixed dye, reduce graying after dyeing, and maintain the fabric's feel and luster. Each cycle of dyeing is repeated on shallow, incompletely fixed layers, allowing dye molecules to gradually penetrate the fiber. Maintaining the fiber in a swollen state at 40°C facilitates rapid desorption of loose dye without dissolving fixed dye.

[0035] S3. Place the dyed fabric in a 0.5-1% polyphenol chelating solution, heat it to 50-60°C and maintain it for 20-30 minutes, take it out and spin dry it, then place it in a 1-1.5% tea polyphenol solution, heat it to 50-60°C and maintain it for 20-30 minutes, and finally immerse it in a composite mordant solution, heat it to 40-50°C and maintain it for 10 minutes to obtain a pretreated fabric.

[0036] In step S3, the polyphenol chelating solution includes at least one of a water-soluble tannin iron complex solution, a gallic acid solution, and an acorn tannic acid solution.

[0037] Step S3 includes: S3.1. Add 0.5-1% polyphenol chelating solution to the dye bucket, heat to 50-60℃, put the dyed fabric in, and control the liquid-to-material ratio of polyphenol chelating solution to dyed fabric at 20:1. Soak for 20-30 minutes while stirring. Take out and spin dry after soaking.

[0038] The polyphenol chelate solution pre-binds with the dye through π-π stacking and hydrogen bonding, forming a thin film that wraps around the fiber surface, exposing more phenolic hydroxyl groups and providing more complexation sites for subsequent mordanting. This initial film reduces the loosening and loss of the dye during subsequent washing or multiple treatments, laying the foundation for deeper color fixation. Metal ions form multidentate chelates with the ortho-hydroxyl groups of tannins and gallic acid, forming a water-insoluble complex. The planar aromatic rings of the polyphenols overlap with the planar molecules of the dioscorea dye, while hydrogen bonds are formed with the hydroxyl / amide groups on the side chains of the silk fibroin. Temperatures of 50–60°C increase molecular motion, accelerating complexation and adsorption.

[0039] In one embodiment, after step S3.1, the method further includes: adding a laccase solution with a concentration of 500 U / L to the dyed product after drying, performing an oxidative polymerization reaction at a temperature of 50° C. for 15 to 20 minutes, and washing and drying the product to perform step S3.2.

[0040] Laccases are copper-dependent oxidases found widely in fungi, yeast, certain plants, and bacteria. Using molecular oxygen as an electron acceptor, they catalyze the oxidation of phenolic hydroxyl compounds (such as polyphenols and phenolamines) into phenolic free radicals, which then polymerize or cross-link with adjacent active sites. Prepare the enzyme by dissolving purified or partially purified laccase powder in an appropriate buffer (e.g., acetic acid-sodium acetate buffer, pH 5.0–6.0) at an activity of 500 U / L.

[0041] Laccase catalyzes the oxidation of polyphenols to generate free radicals. These free radicals form phenol-formaldehyde covalent bonds or diphenyl ether bonds between the fiber surface and adjacent polyphenol or dye molecules, building a stable three-dimensional cross-linked network and significantly enhancing washability and abrasion resistance. The enzymatic reaction generates micron- and nanometer-scale cross-linked polymers within the existing physical adsorption and metal complexation layers, transforming the color-fixing film from a loosely packed structure to a densely cross-linked structure, improving color fastness while retaining the fiber's soft feel. The reaction is completed at 50°C in 15–20 minutes, eliminating the need for regeneration agents or high-temperature and high-pressure equipment. This reduces thermal damage to the fiber, is energy-efficient, and facilitates industrial scale-up. The phenolic network generated by the laccase layer possesses a certain degree of antioxidant capacity and synergizes with the subsequent tea polyphenol and metal mordant layers to further enhance overall light fastness and weathering resistance.

[0042] S3.2. Immerse the dried dyed fabric in a preheated tea polyphenol solution at 50-60°C for 20-30 minutes, and allow to cool naturally after treatment.

[0043] Tea polyphenol molecules further form a cross-linked network on the already coated polyphenol-metal layer, increasing the film thickness and density. The strong antioxidant properties of tea polyphenols inhibit the photooxidative degradation of dyes, improving light fastness. Tea polyphenol molecules are smaller and can penetrate into the fiber micropores, interacting more with the dye molecules within the fiber and improving washability. The phenolic hydroxyl groups of tea polyphenols form hydrogen bonds and metal bridges with the carboxyl groups / metal centers in the tannin layer. Tea polyphenols can capture free radicals, preventing the degradation of dye molecules during subsequent exposure or washing. Temperature and agitation ensure that the tea polyphenols are evenly adsorbed and penetrate the fiber pores.

[0044] S3.3. Place the cooled dyed fabric into the composite mordant solution, heat it to 40-50°C, maintain the treatment for 10 minutes, take it out after the treatment, rinse it with clean water 1-2 times, and dry it to obtain the pretreated fabric.

[0045] In step S3, the composite mordant solution includes an aluminum source, a zirconium source and a titanium source, the aluminum source includes at least one of aluminum chloride, aluminum sulfate and aluminum acetate, the zirconium source includes at least one of zirconium oxychloride, zirconium sulfate and zirconium acetate, and the titanium source includes at least one of titanium tetrachloride, potassium titanate and titanium citrate complex.

[0046] Aluminum, zirconium, and titanium sources successively form stable coordination bonds with the phenolic hydroxyl and carbonyl groups of the polyphenols and dyes, as well as the hydroxyl and amine groups of the fibers, creating a three-dimensional network of crosslinked structures. The dye-metal complexes catalyzed by the metal ions have extremely low water solubility, significantly improving resistance to washing, perspiration, and rubbing.

[0047] Titanium ions inherently possess UV absorption and photocatalytic blocking properties, forming a thin titanium oxide film on the fiber surface, improving color stability. Hydrolysis generates micron / nano titanium dioxide particles on the fiber surface, which serve both UV shielding and cross-linking fixation. Aluminum ions interact simultaneously with the fiber and dye molecules, forming a bridge. Zirconium ions have a high charge density, forming a dense complex layer that is resistant to acid and alkali washing. S4. Evenly apply the red-brown mud coating slurry to the pretreated fabric, expose it to the sun, then wash and dry it, and shape it to obtain Xiangyun yarn.

[0048] Step S4 includes: S4.1. Add deionized water to the mud material and dilute it in a mass ratio of 1:3. Stir and disperse it for 20 minutes. Filter it with a 200-mesh sieve and let it stand for degassing for 1 hour to obtain a red-brown mud coating slurry.

[0049] Oversized particles are removed to produce fine, uniform mud particles, facilitating subsequent coating. After stirring and degassing, the slurry is free of noticeable bubbles and sedimentation, preventing holes or faults in the coating. Minerals such as iron oxide, silicon dioxide, aluminum oxide, and kaolin are retained in the mud, ensuring subsequent color development and adhesion. High-speed shearing disperses the mud particles, while the screen physically intercepts coarse particles. Static degassing eliminates bubbles, forming a dense suspension system. Iron oxide forms a color-forming complex with the dye during sun exposure, silicon dioxide and aluminum oxide increase coating hardness, and kaolin enhances adhesion and feel.

[0050] S4.2. Lay the pretreated fabric flat under a scraper and apply the red-brown mud coating slurry 1 to 2 times with controlled thickness. Let it stand for 10 minutes after coating to obtain a mud fabric composition.

[0051] Precise scraping ensures complete coverage without cracking. The mud penetrates the uneven surface of the fiber, forming a smooth composite interface. The mud tightly bonds with the color fixation layer, providing a foundation for subsequent photooxidation fixation. The pressure of the scraping presses the mud into the fiber cracks, enhancing the mechanical bite. During the static period, the mineral particles in the mud interlock with the polyphenol layer, improving the bonding stability.

[0052] S4.3. Hang the mud-textile combination on a drying rack for sun exposure. Turn the fabric over every 2-3 hours during the exposure period. During non-sun exposure periods, use a combination of 365nm wavelength and visible light lamps for additional sun exposure for 12-18 hours. In one embodiment, the combination lamps can be used for all exposures.

[0053] Under sunlight and ultraviolet light, the dye and polyphenol layer undergo free radical polymerization, forming insoluble polymers. The iron oxide in the mud chelates with the dye's phenolic hydroxyl groups, forming a stable color layer. Repeated drying ensures uniform light exposure, resulting in a dense, wear-resistant, and seamless color-fixing layer. Iron oxide activates the dye molecules under light and allows them to complex with metal ions. Free radical polymerization of the polyphenols and dye forms a cross-linked network, enhancing water and light fastness.

[0054] S4.4. After exposure to the sun, place the mud fabric composition in water at 35-40°C, stir for 10 minutes, and repeat rinsing 2-3 times until the washing water is no longer obviously turbid. After drying in the shade, use hot air drying at 90-100°C, and then press and shape for 3-5 minutes to obtain Xiangyunsha.

[0055] Warm water washes away unbound mud and weakly complexed components, restoring the fiber's softness. Hot air drying removes residual moisture and promotes the thermal curing of the iron oxide-dye-fiber complex. Pressing sets the fiber's shape and creates a unique wrinkled finish, stabilizing its size and feel. Warm water maintains fiber expansion, facilitating cleaning. High temperatures promote the thermal curing of the complexation network, while pressing evens out the fiber's microstructure and enhances its light reflectivity.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high color fastness Xiangyun yarn dyeing method, characterized in that the steps include: S1. Soaking a coarse Xiangyunsha fabric in 0.5-1% polycarboxylic acid buffer at 40-50° C. for 30 minutes and drying it at room temperature to obtain a silk fabric; S2, heating the Dioscorea scoparia extract to 80-100° C., adjusting the pH to 5.5-6.0, placing the silk fabric into the Dioscorea scoparia extract, and maintaining the temperature for 60 minutes to obtain a dyed fabric; S3, placing the dyed fabric in a 0.5-1% polyphenol chelating solution, heating it to 50-60°C for 20-30 minutes, taking it out and drying it, then placing it in a 1-1.5% tea polyphenol solution, heating it to 50-60°C for 20-30 minutes, and finally immersing it in a composite mordant solution, heating it to 40-50°C for 10 minutes to obtain a pretreated fabric; S4. Evenly apply red-brown mud coating slurry to the pretreated fabric, expose it to the sun, then wash and dry it, and obtain Xiangyunsha after shaping.

2. The method for dyeing Xiangyun yarn with high color fastness according to claim 1, characterized in that: In step S1, the polycarboxylic acid buffer comprises at least one of citric acid buffer, oxalic acid buffer, tartaric acid buffer, maleic acid buffer, and succinic acid buffer.

3. A high color fastness Xiangyun yarn dyeing method according to claim 1 or 2, characterized in that, Step S1 includes: S1.

1. Completely immerse the coarse Xiangyunsha fabric in a 0.5-1% polycarboxylic acid buffer solution preheated at 40-50°C. The ratio of polycarboxylic acid buffer to the coarse Xiangyunsha fabric should be controlled at 20:

1. Soak for 30 minutes, stirring regularly. S1.

2. Rinse the fabric with deionized water three times, each time for 5 minutes, until the pH of the cleaning solution reaches 5.0±0.

3. After cleaning, dry the fabric naturally at room temperature to obtain a silk fabric.

4. The method for dyeing Xiangyun yarn with high color fastness according to claim 1, characterized in that: Step S2 includes: S2.

1. Weigh radix serrata powder and add it to deionized water. Heat to 90-95°C and stir at this temperature for 1 hour. Then filter through a 300-mesh nylon cloth to obtain a clear brown-red dye solution. S2.

2. Adjust the pH of the clarified brown-red dye solution to 5.5-6.0 using diluted citric acid buffer or lactic acid buffer. S2.

3. Heat the clarified brownish-red dye solution to 80-100°C. After the temperature stabilizes, lay the silk fabric flat on the clarified brownish-red dye solution. The liquid-to-material ratio of the clarified brownish-red dye solution to the silk fabric should be controlled at (20-30):

1. S2.

4. Maintain the temperature at 80-90°C, immerse for 10 minutes, then remove from the dye and allow to stand in the air for natural oxidation for 10 minutes. S2.

5. Repeat step S2.4 for 3 to 5 rounds, with the total time controlled within 60 minutes. After dyeing, cool naturally to 40°C, then use 40°C deionized warm water to soak 3 times, and ventilate and dry in the shade to obtain the dyed fabric.

5. The method for dyeing Xiangyun yarn with high color fastness according to claim 1, characterized in that: In step S3, the polyphenol chelating solution includes at least one of a water-soluble tannin iron complex solution, a gallic acid solution, and an acorn tannic acid solution.

6. The method for dyeing Xiangyun yarn with high color fastness according to claim 1, characterized in that: In step S3, the composite mordant solution includes an aluminum source, a zirconium source and a titanium source, the aluminum source includes at least one of aluminum chloride, aluminum sulfate and aluminum acetate, the zirconium source includes at least one of zirconium oxychloride, zirconium sulfate and zirconium acetate, and the titanium source includes at least one of titanium tetrachloride, potassium titanate and titanium citrate complex.

7. The method for dyeing Xiangyun yarn with high color fastness according to claim 1, characterized in that: Step S3 includes: S3.

1. Add 0.5-1% polyphenol chelate solution to the dye bucket, heat to 50-60°C, add the dyed fabric, and control the liquid-to-material ratio of polyphenol chelate solution to dyed fabric to be 20:

1. Soak for 20-30 minutes while stirring. Remove from the dye bucket and spin dry after soaking. S3.

2. Immerse the dried dyed fabric in a preheated tea polyphenol solution at 50-60°C for 20-30 minutes, then allow to cool naturally after treatment. S3.

3. Place the cooled dyed fabric into the composite mordant solution, heat it to 40-50°C, maintain the treatment for 10 minutes, take it out after the treatment, rinse it with clean water 1-2 times, and dry it to obtain the pretreated fabric.

8. The method for dyeing Xiangyun yarn with high color fastness according to claim 1, characterized in that: Step S4 includes: S4.

1. Add deionized water to the mud material in a mass ratio of 1:3, stir and disperse for 20 minutes, filter through a 200-mesh sieve, and let it stand for degassing for 1 hour to obtain a red-brown mud coating slurry; S4.

2. Lay the pretreated fabric flat under a scraper and apply the red-brown mud coating slurry 1 to 2 times with controlled thickness. Let it stand for 10 minutes after application to obtain a mud fabric composition. S4.

3. Hang the mud-fabric combination on a drying rack for sun exposure, turning it over every 2-3 hours during the exposure period. During the non-sun exposure period, use a combination of 365 nm wavelength and visible light lamps for additional sun exposure for 12-18 hours. S4.

4. After exposure to the sun, place the mud fabric composition in water at 35-40°C, stir for 10 minutes, and repeat rinsing 2-3 times until the washing water is no longer obviously turbid. After drying in the shade, use hot air drying at 90-100°C, and then press and shape for 3-5 minutes to obtain Xiangyunsha.

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