Processing method for improving sunlight fastness of cotton and linen fabric

Abstract

The application discloses a processing method for improving the sunlight fastness of cotton and hemp fabric, and belongs to the technical field of textile dyeing and finishing, and comprises four steps of treatment: firstly, acid complex enzyme, eutectic solvent and synergist are used for mild impurity removal, so that the original style of the fabric is reserved; secondly, a fixing agent and an ionic liquid are used to improve the sunlight fastness; thirdly, a capturing agent and a stabilizer are used to fully remove free fixing agent; and finally, a buffer microcapsule, amino silicon oil and a free radical absorber are used to further improve the washing resistance and hand feeling. The method can endow the cotton and hemp fabric with natural style and soft hand feeling, and significantly improve the sunlight fastness and washing resistance of the cotton and hemp fabric.

Description

Technical Field

[0001] This invention belongs to the field of textile dyeing and finishing technology, and specifically relates to a processing method for improving the light fastness of cotton and linen fabrics. Background Technology

[0002] Flax fiber, a natural fiber with a long history, is widely used in bedding due to its superior performance. This fiber possesses excellent moisture absorption and release capabilities, good thermal conductivity, and provides a dry and breathable comfort when in contact with the skin. To mitigate the relatively rough feel of flax fiber, it is often blended with cotton fiber. Bedding fabrics made from this blend retain the inherent advantages of flax while effectively enhancing its skin-friendliness and softness, achieving a balance between functionality and comfort. To preserve the original natural colors of flax and cotton fibers and present their rustic style and natural charm, these fabrics are typically not bleached during the dyeing and finishing process. However, the natural pigments in unbleached fibers are less stable, resulting in poor colorfastness to sunlight in the final fabric. This issue not only limits the application scenarios of the product but also affects its long-term durability to some extent.

[0003] To address the issue of poor lightfastness of cotton and linen fabrics, the applicant conducted extensive experiments, using various lightfastness improvers such as UV absorbers, UV blockers, UV quenchers, and hindered phenolic antioxidants, either alone or in combination. However, no significant improvement was achieved. Therefore, given the demand for cotton and linen fabrics that emphasize natural texture and a rustic style, those skilled in the art urgently need to develop a novel dyeing and finishing technology that can significantly improve their lightfastness. This technological breakthrough will effectively solve the industry pain point of insufficient lightfastness in cotton and linen blended fabrics, further enhancing the durability and quality stability of the products. Summary of the Invention

[0004] Technical problem to be solved: For cotton and linen fabrics with natural texture and rustic style, the existing technology has the following technical defects: the flax fiber itself has a relatively rough touch, and the natural pigment stability of the unbleached fiber is weak, resulting in poor light fastness of the final fabric. This problem not only restricts the application scenarios of the product, but also affects its long-term durability to a certain extent. This application provides a processing method to improve the light fastness of cotton and linen fabrics.

[0005] Purpose of the invention: The purpose of this invention is to provide a processing method to improve the light fastness of cotton and linen fabrics, and to provide a novel dyeing and finishing technology that can significantly improve their light fastness, thereby further enhancing the durability and quality stability of the products.

[0006] The specific technical solution is as follows: A processing method for improving the lightfastness of cotton and linen fabrics, specifically including the following steps: Step S1: Mix 20-35 parts of acidic compound enzyme, 20-40 parts of eutectic solvent, 2-4 parts of synergist and 1000 parts of deionized water according to the mass ratio. After stirring thoroughly, the first treatment solution is obtained. Add cotton and linen fabrics to the first treatment solution at a bath ratio of 1:1-3. Keep the fabrics in a dyeing machine at 60℃~80℃ for 120min~180min. Then drain the first treatment solution and wash with clean water. Step S2: Mix 1-3 parts of fixing agent, 50-100 parts of ionic liquid and 1000 parts of deionized water according to the mass ratio, stir evenly to obtain the second treatment solution, and keep the fabric treated in step S1 in the second treatment solution at 40℃~60℃ for 120min~180min at a bath ratio of 1:3-5, and then drain the second treatment solution. Step S3: Take 2-5 parts of the capture agent and 1000 parts of deionized water according to the mass ratio and mix them thoroughly to obtain the third treatment solution. Treat the fabric treated in step S2 in the third treatment solution at a bath ratio of 1:1-3 for 30 min to 60 min. Then add 5-10 parts of stabilizer to the third treatment solution, heat to 30-50℃ and keep warm for 60-120 min. Drain the third treatment solution and wash with clean water. Step S4: Mix 20-50 parts of buffer microcapsules, 30-50 parts of softener, 10-30 parts of free radical absorber, 1-5 parts of emulsifying dispersant and 1000 parts of deionized water according to the mass ratio. After thorough stirring, the fourth treatment solution is obtained. The fabric treated in step S3 is treated in the fourth treatment solution at a bath ratio of 1:1-3 for 30-60 minutes. After that, the fourth treatment solution is drained. The treated fabric is taken out of the dyeing machine and dried to complete the processing.

[0007] Further, in step S1, the acidic complex enzyme is one or more of acidic amylase, acidic pectinase, acidic lipase, acidic xylanase, and acidic hemicellulase; the eutectic solvent is choline chloride / lactic acid, choline chloride / citric acid, or choline chloride / malic acid in a molar mass ratio of 1:1; and the synergist is one or more of rhamnolipid, sophorolipid, and trehalolipid.

[0008] Further, in step S1, the concentrations of acidic amylase, acidic pectinase, acidic lipase, acidic xylanase, acidic hemicellulase, eutectic solvent, and synergist are 5-8 g / L, 8-12 g / L, 2-4 g / L, 3-6 g / L, 2-5 g / L, 20-40 g / L, and 2-4 g / L, and the pH of the first treatment solution is adjusted to 4-5 with sodium hydroxide.

[0009] Further, in step S2, the fixing agent is one or more of cerium chloride, cerium nitrate, cerium sulfate, lanthanum chloride, lanthanum sulfate, lanthanum nitrate, and stannous chloride; the ionic liquid is one or more of 1-butyl-3-methylimidazolium acetate, 1-propyl-3-methylimidazolium acetate, and 1-ethyl-3-methylimidazolium acetate.

[0010] Furthermore, in step S2, the concentration of the fixing agent is 1-3 g / L, the concentration of the ionic liquid is 50-100 g / L, and the pH of the second treatment solution is adjusted to 5-6 with acetic acid.

[0011] Further, in step S3, the capturing agent is one or more of sodium octanoate, sodium nonanoate, and sodium decanoate; the stabilizer is one or more of methyl-β-cyclodextrin, hydroxypropyl-β-cyclodextrin, and carboxymethyl-β-cyclodextrin.

[0012] Furthermore, in step S3, the concentration of the trapping agent is 2-5 g / L, and the concentration of the stabilizer is 5-10 g / L.

[0013] Further, in step S4, the core material of the buffer microcapsule is disodium hydrogen phosphate and potassium dihydrogen phosphate, and the wall material is ethyl cellulose; the softener is amino silicone oil; the free radical absorber is BASF Tinuvin 123-DW, and the emulsifying dispersant is Tween 20.

[0014] Further, in step S4, the mass ratio of disodium hydrogen phosphate to potassium dihydrogen phosphate is 2-5:1, the mass ratio of core material to wall material is 1-2:10, the concentration of buffer microcapsules is 20-50 g / L, the concentration of softener is 30-50 g / L, the concentration of free radical absorber is 10-30 g / L, the concentration of emulsifying dispersant is 1-5 g / L, and the drying temperature is 120-150℃.

[0015] Furthermore, the warp of the cotton-linen fabric is made of pure cotton yarn, and the weft is made of a blend of cotton and flax fibers.

[0016] Explanation of the principle: Traditional pretreatment processes for cotton and linen fabrics are completed under alkaline conditions. Alkalinity easily leads to the oxidation and darkening of natural pigments, and excessive swelling and shedding of cotton seeds and linen bark. This application utilizes an acidic complex enzyme in the first treatment solution to gently and efficiently remove most impurities from cotton and linen fabrics, such as sizing agents, pectin, cotton wax, ash, and linen byproducts. A eutectic solvent provides a favorable acidic environment for the treatment solution, while simultaneously promoting the dissolution of various impurities by the complex enzyme. The synergist promotes the penetration of the treatment solution, enhances the contact efficiency between the acidic complex enzyme and the fabric, and prevents the re-adhesion of shed impurities. This "acidic closed-loop" pretreatment process gently and efficiently removes impurities while avoiding damage to natural pigments and fabric style caused by strong alkali, preserving the original natural texture and visual style of the fabric to the greatest extent. After treatment, the fabric surface pH is 6-6.5, which is weakly acidic, and the wicking effect can reach over 10cm / 30min, providing excellent conditions for subsequent color fixing. The color fixing agent selected in the second treatment solution can complex with the natural pigments of the cotton and linen fabric to form more stable chromophores. The selected ionic liquid provides a stable, weakly acidic environment for the fixing agent and also has a swelling effect on the fibers, promoting the penetration of the fixing agent into the fabric. The synergistic effect of these two factors greatly improves the light fastness of the fabric. In the third treatment solution, a scavenging agent with hydrophobic long-chain anions is first used to react with the fixing agent remaining on the fabric surface after fixing to form a hydrophobic substance. Then, a stabilizer with hydrophobic cavities is used to encapsulate the reactants, increasing their dispersion stability in the treatment solution and preventing them from adhering back to the fabric surface. This fully extracts the free fixing agent adsorbed on the fabric surface and completely removes it during the subsequent washing process. At the same time, this process has no effect on the complexation structure between the fixing agent and the cotton and linen pigments formed on the fabric surface, that is, it does not affect the light fastness of the fabric. After multiple experiments, the applicant found that although the cotton and linen fabrics treated with the first three treatment solutions have good initial light fastness, after multiple washes, the light fastness returns to the level before fixing. In the fourth treatment solution, the use of buffer microcapsules can stabilize the pH of the fabric surface at 7-7.5. Simultaneously, it exhibits excellent pH buffering properties against various acidic and alkaline detergents during daily washing, effectively resolving the issues of lightfastness and washability. The presumably, this is because the complex structure between the color-fixing agent and cotton / linen pigments exists in a more thermodynamically stable form during pH transitions from weakly acidic to weakly alkaline, further enhancing the stability of the complex structure and slowing down the dissociation rate of the complex under daily washing conditions, thus significantly improving the fabric's lightfastness and washability. Furthermore, to ensure a soft hand feel, amino silicone oil softeners are often used to finish the fabric; however, the applicant discovered that after the first three treatment solutions... The cotton and linen fabrics treated with amino silicone oil exhibited poor lightfastness. The presumed reason is not that the complex structure between the fixing agent and the cotton / linen pigments was destroyed during the softening process, but rather that the fixing agent complexed on the fabric catalyzed the amino silicone oil to produce a large amount of high-energy reactive oxygen species, which then destroyed the chromophores already stably complexed on the fabric. However, without amino silicone oil, normal ultraviolet irradiation does not destroy the complex structure of these chromophores. Therefore, the applicant simultaneously added a free radical absorber to the fourth treatment solution, ensuring good washability and lightfastness of the cotton and linen fabrics while giving them a soft hand feel.

[0017] This invention, through a four-step synergistic process, imparts a natural style and soft feel to cotton and linen fabrics while significantly improving their lightfastness and washability, offering the following beneficial effects: (1) Using an acidic complex enzyme system to gently remove impurities, preserving the natural color and style of the fabric to the greatest extent, avoiding pigment oxidation and fabric style damage caused by traditional alkali treatment, and creating conditions for subsequent color fixing; (2) By forming a stable complex structure with cotton and linen pigments through the color-fixing agent, the ionic liquid provides a stable acidic environment and promotes fiber swelling, thus significantly improving the light fastness to grade 3 or above. (3) Use trapping agents and stabilizers to selectively remove free fixing agents, prevent re-adhesion and side reactions, and ensure the long-term stability of the complex structure; (4) Introducing buffer microcapsules stabilizes the pH of the fabric surface, slows down the dissociation of complexes during washing, and further improves the light fastness and washability; at the same time, adding amino silicone oil and free radical absorbent inhibits the damage of reactive oxygen to pigments, thus taking into account both light fastness and hand feel. Detailed Implementation

[0018] The preferred embodiments of the present invention will now be described in detail with reference to specific examples. It should be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and essence.

[0019] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0020] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0021] Example 1: A processing method for improving the light fastness of cotton and linen fabrics, specifically including the following steps: Step S1: Add 8 g / L acidic amylase, 12 g / L acidic pectinase, 4 g / L acidic lipase, 6 g / L acidic xylanase, 5 g / L acidic hemicellulase, 40 g / L choline chloride / lactic acid in a 1:1 molar ratio, and 4 g / L rhamnolipid to deionized water. Stir thoroughly and adjust the pH of the first treatment solution to 4 with sodium hydroxide to obtain the first treatment solution. Add cotton and linen fabrics to the first treatment solution at a bath ratio of 1:1, and keep them at 80℃ for 120 minutes in a dyeing machine. Then drain the first treatment solution and wash with clean water. Step S2: Add 3 g / L cerium chloride and 100 g / L 1-butyl-3-methylimidazolium acetate to deionized water, stir evenly, and adjust the pH of the treatment solution to 5 with acetic acid to obtain the second treatment solution. The fabric treated in step S1 is kept in the second treatment solution at 40°C for 180 min at a bath ratio of 1:3, and then the second treatment solution is drained. Step S3: Add 5g / L sodium octanoate to deionized water and stir thoroughly to obtain the third treatment solution. Treat the fabric treated in step S2 in the third treatment solution at a bath ratio of 1:1 for 60 minutes. Then add 10g / L methyl-β-cyclodextrin to the third treatment solution, heat to 30℃ and keep warm for 120 minutes. Drain the third treatment solution and wash with clean water. Step S4: Add 50 g / L buffer microcapsules (the mass ratio of disodium hydrogen phosphate to potassium dihydrogen phosphate in the core material is 2:1, and the mass ratio of the core material to ethyl cellulose is 1:10), 50 g / L amino silicone oil, 30 g / L BASF Tinuvin 123-DW, and 5 g / L Tween 20 to deionized water. After thorough stirring, the fourth treatment solution is obtained. The fabric treated in step S3 is treated in the fourth treatment solution at a bath ratio of 1:1 for 60 minutes, and then the fourth treatment solution is drained. The treated fabric is taken out of the dyeing machine and dried at 150°C to complete the processing.

[0022] Example 2: A processing method for improving the lightfastness of cotton and linen fabrics, specifically including the following steps: Step S1: Add 5 g / L acidic amylase, 8 g / L acidic pectinase, 2 g / L acidic lipase, 3 g / L acidic xylanase, 2 g / L acidic hemicellulase, 20 g / L choline chloride / malic acid in a molar ratio of 1:1, and 2 g / L sophorolipid to deionized water. Stir thoroughly and adjust the pH of the first treatment solution to 5 with sodium hydroxide to obtain the first treatment solution. Add cotton and linen fabrics to the first treatment solution at a bath ratio of 1:3, and keep them at 60℃ for 180 minutes in a dyeing machine. Then drain the first treatment solution and wash with clean water. Step S2: Add 1 g / L lanthanum chloride and 50 g / L 1-propyl-3-methylimidazolium acetate to deionized water, stir evenly, and adjust the pH of the treatment solution to 6 with acetic acid to obtain the second treatment solution. The fabric treated in step S1 is kept in the second treatment solution at 60°C for 120 min at a bath ratio of 1:5, and then the second treatment solution is drained. Step S3: Add 2g / L sodium nonanoate to deionized water and stir thoroughly to obtain the third treatment solution. Treat the fabric treated in step S2 in the third treatment solution at a bath ratio of 1:3 for 30 minutes. Then add 5g / L hydroxypropyl-β-cyclodextrin to the third treatment solution, heat to 50℃ and keep warm for 60 minutes. Drain the third treatment solution and wash with clean water. Step S4: Add 20 g / L buffer microcapsules (the mass ratio of disodium hydrogen phosphate to potassium dihydrogen phosphate in the core material is 5:1, and the mass ratio of the core material to ethyl cellulose is 2:10), 30 g / L amino silicone oil, 10 g / L BASF Tinuvin 123-DW, and 1 g / L Tween 20 to deionized water. After thorough stirring, the fourth treatment solution is obtained. The fabric treated in step S3 is treated in the fourth treatment solution at a bath ratio of 1:3 for 30 minutes, and then the fourth treatment solution is drained. The treated fabric is taken out of the dyeing machine and dried at 120°C to complete the processing.

[0023] Example 3: A processing method for improving the lightfastness of cotton and linen fabrics, specifically including the following steps: Step S1: Add 6 g / L acidic amylase, 10 g / L acidic pectinase, 3 g / L acidic lipase, 5 g / L acidic xylanase, 3 g / L acidic hemicellulase, 30 g / L choline chloride / citric acid in a molar ratio of 1:1, and 3 g / L rhamnolipid to deionized water. After stirring thoroughly, adjust the pH of the first treatment solution to 4.5 with sodium hydroxide to obtain the first treatment solution. Add cotton and linen fabrics to the first treatment solution at a bath ratio of 1:2, and keep them at 70℃ for 150 minutes in a dyeing machine. Then drain the first treatment solution and wash with clean water. Step S2: Add 2 g / L stannous chloride and 75 g / L 1-ethyl-3-methylimidazolium acetate to deionized water, stir evenly, and adjust the pH of the treatment solution to 5.5 with acetic acid to obtain the second treatment solution. The fabric treated in step S1 is kept in the second treatment solution at 50°C for 150 min at a bath ratio of 1:2, and then the second treatment solution is drained. Step S3: Add 3g / L sodium decanoate to deionized water and stir thoroughly to obtain the third treatment solution. Treat the fabric treated in step S2 in the third treatment solution at a bath ratio of 1:2 for 40 minutes. Then add 8g / L carboxymethyl-β-cyclodextrin to the third treatment solution, heat to 40℃ and keep warm for 100 minutes. Drain the third treatment solution and wash with clean water. Step S4: Add 35 g / L buffer microcapsules (the mass ratio of disodium hydrogen phosphate to potassium dihydrogen phosphate in the core material is 3.5:1, and the mass ratio of the core material to ethyl cellulose is 1.5:10), 40 g / L amino silicone oil, 20 g / L BASF Tinuvin 123-DW, and 3 g / L Tween 20 to deionized water. After thorough stirring, the fourth treatment solution is obtained. The fabric treated in step S3 is treated in the fourth treatment solution at a bath ratio of 1:2 for 45 minutes, and then the fourth treatment solution is drained. The treated fabric is taken out of the dyeing machine and dried at 135℃ to complete the processing.

[0024] Example 4: A processing method for improving the lightfastness of cotton and linen fabrics, specifically including the following steps: Step S1: Add 8 g / L acidic amylase, 12 g / L acidic pectinase, 4 g / L acidic lipase, 6 g / L acidic xylanase, 5 g / L acidic hemicellulase, 40 g / L choline chloride / lactic acid in a 1:1 molar ratio, and 4 g / L rhamnolipid to deionized water. Stir thoroughly and adjust the pH of the first treatment solution to 4 with sodium hydroxide to obtain the first treatment solution. Add cotton and linen fabrics to the first treatment solution at a bath ratio of 1:1, and keep them at 80℃ for 120 minutes in a dyeing machine. Then drain the first treatment solution and wash with clean water. Step S2: Add 3 g / L cerium sulfate and 100 g / L 1-butyl-3-methylimidazolium acetate to deionized water, stir evenly, and adjust the pH of the treatment solution to 5 with acetic acid to obtain the second treatment solution. The fabric treated in step S1 is kept in the second treatment solution at 40°C for 180 min at a bath ratio of 1:3, and then the second treatment solution is drained. Step S3: Add 5g / L sodium octanoate to deionized water and stir thoroughly to obtain the third treatment solution. Treat the fabric treated in step S2 in the third treatment solution at a bath ratio of 1:1 for 60 minutes. Then add 10g / L methyl-β-cyclodextrin to the third treatment solution, heat to 30℃ and keep warm for 120 minutes. Drain the third treatment solution and wash with clean water. Step S4: Add 50 g / L buffer microcapsules (the mass ratio of disodium hydrogen phosphate to potassium dihydrogen phosphate in the core material is 2:1, and the mass ratio of the core material to ethyl cellulose is 1:10), 50 g / L amino silicone oil, 30 g / L BASF Tinuvin 123-DW, and 5 g / L Tween 20 to deionized water. After thorough stirring, the fourth treatment solution is obtained. The fabric treated in step S3 is treated in the fourth treatment solution at a bath ratio of 1:1 for 60 minutes, and then the fourth treatment solution is drained. The treated fabric is taken out of the dyeing machine and dried at 150°C to complete the processing.

[0025] Example 5: A processing method for improving the lightfastness of cotton and linen fabrics, specifically including the following steps: Step S1: Add 8 g / L acidic amylase, 12 g / L acidic pectinase, 4 g / L acidic lipase, 6 g / L acidic xylanase, 5 g / L acidic hemicellulase, 40 g / L choline chloride / lactic acid in a 1:1 molar ratio, and 4 g / L rhamnolipid to deionized water. Stir thoroughly and adjust the pH of the first treatment solution to 4 with sodium hydroxide to obtain the first treatment solution. Add cotton and linen fabrics to the first treatment solution at a bath ratio of 1:1, and keep them at 80℃ for 120 minutes in a dyeing machine. Then drain the first treatment solution and wash with clean water. Step S2: Add 3 g / L lanthanum nitrate and 100 g / L 1-butyl-3-methylimidazolium acetate to deionized water, stir evenly, and adjust the pH of the treatment solution to 5 with acetic acid to obtain the second treatment solution. The fabric treated in step S1 is kept in the second treatment solution at 40°C for 180 min at a bath ratio of 1:3, and then the second treatment solution is drained. Step S3: Add 5g / L sodium octanoate to deionized water and stir thoroughly to obtain the third treatment solution. Treat the fabric treated in step S2 in the third treatment solution at a bath ratio of 1:1 for 60 minutes. Then add 10g / L methyl-β-cyclodextrin to the third treatment solution, heat to 30℃ and keep warm for 120 minutes. Drain the third treatment solution and wash with clean water. Step S4: Add 50 g / L buffer microcapsules (the mass ratio of disodium hydrogen phosphate to potassium dihydrogen phosphate in the core material is 2:1, and the mass ratio of the core material to ethyl cellulose is 1:10), 50 g / L amino silicone oil, 30 g / L BASF Tinuvin 123-DW, and 5 g / L Tween 20 to deionized water. After thorough stirring, the fourth treatment solution is obtained. The fabric treated in step S3 is treated in the fourth treatment solution at a bath ratio of 1:1 for 60 minutes, and then the fourth treatment solution is drained. The treated fabric is taken out of the dyeing machine and dried at 150°C to complete the processing.

[0026] Comparative Example 1 differs from Example 1 in that the "acidic closed-loop" pretreatment process in the first treatment solution is replaced with a conventional desizing, refining, and alkali boiling process. The concentrations of desizing enzyme, refining enzyme, refining agent, and caustic soda in the treatment solution are 5 g / L, 20 g / L, 5 g / L, and 30 g / L, respectively.

[0027] In Comparative Example 2, unlike Example 1, cerium chloride was not added to the second treatment solution.

[0028] In Comparative Example 3, unlike Example 1, 1-butyl-3-methylimidazolium acetate was not added to the second treatment solution; instead, the pH was adjusted to 5 using acetic acid-sodium acetate.

[0029] Comparative Example 4 differs from Example 1 in that the pH of the second treatment solution was adjusted to 4.5 using acetic acid.

[0030] Comparative Example 5 differs from Example 1 in that the pH of the second treatment solution was adjusted to 6.5 using acetic acid.

[0031] Comparative Example 6 differs from Example 1 in that the 1-butyl-3-methylimidazolium acetate in the second treatment solution is replaced with 1-butyl-3-methylimidazolium carboxylate.

[0032] Comparative Example 7 differs from Example 1 in that sodium octanoate was not added to the third treatment solution.

[0033] In Comparative Example 8, unlike Example 1, sodium octanoate was replaced with oxalic acid in the third treatment solution.

[0034] Comparative Example 9 differs from Example 1 in that methyl-β-cyclodextrin was not added to the third treatment solution.

[0035] Comparative Example 10 differs from Example 1 in that no buffer microcapsules were added to the fourth treatment solution.

[0036] In Comparative Example 11, unlike Example 1, the mass ratio of disodium hydrogen phosphate to potassium dihydrogen phosphate in the buffer microcapsules of the fourth treatment solution was 6:1.

[0037] Comparative Example 12 differs from Example 1 in that BASF Tinuvin 123-DW was not added to the fourth treatment solution.

[0038] Comparative Example 13 differs from Example 1 in that BASF Tinuvin 123-DW in the fourth treatment solution is replaced with BASF Tinuvin 1130.

[0039] Comparative Example 14 differs from Example 1 in that the amino silicone oil in the fourth treatment solution is replaced with dimethyl silicone oil, and no free radical absorber is added.

[0040] The light fastness of the fabrics was tested and rated according to Method 3 in GB / T 8427-2019 "Textiles - Tests for Color Fastness to Artificial Light: Xenon Arc". The washing procedure was 20 washes using the 4N program in GB / T 8629-2017 "Textiles - Test Procedures for Household Washing and Drying". Drying was performed using method A. The test results for Examples 1-5 and Comparative Examples 1-14 are shown in Table 1.

[0041] Table 1 .

[0042] Examples 1-5 show a lightfastness rating of 3 or higher and good washability. The fabric exhibits a natural texture and a soft feel. Compared to Example 1, Comparative Example 1, after alkaline treatment, shows a yellowish and dull fabric, lacking a natural style. The high pH causes the fixing agent to precipitate rather than complex, resulting in substandard lightfastness and a stiff feel. In Comparative Example 2, the unfixed cotton and linen pigments exhibit very poor stability under UV irradiation, leading to substandard lightfastness. In Comparative Example 3, the acetate-sodium acetate in the second treatment solution only provides a pH buffer but cannot swell the fibers, preventing the fixing agent from diffusing deep into the fibers, resulting in insufficient fixation and poor washability. In Comparative Example 4, the low pH in the second treatment solution causes excessive protons to compete with the fixing agent for complexation sites on the cotton and linen pigments, resulting in a lower content of fixing agent complexed with the pigments. In Comparative Example 5, the second treatment solution had a high pH and insufficient acidity, causing some fixing agents to precipitate rather than complex with the fabric surface. This resulted in insufficient fixing agent content to complex with cotton and linen pigments, leading to inadequate color fixation, poor wash resistance, and a stiff hand feel. In Comparative Example 6, the formate in the second treatment solution had a stronger complexing ability than acetate, causing it to complex with the fixing agent. This also resulted in insufficient fixing agent content to complex with cotton and linen pigments, leading to inadequate color fixation and poor wash resistance. In Comparative Example 7, no capturing agent was added to the third treatment solution, leaving a large amount of free fixing agent on the fabric surface. This residue easily precipitates onto the fabric surface during subsequent treatments and accelerates the generation of free radicals, ultimately resulting in substandard lightfastness and a stiff hand feel. The fabric was stiff. In Comparative Example 8, the oxalic acid added to the third treatment solution could extract the free fixative from the fabric surface, but its strong chelating ability destroyed the complexation structure between the fixative and the cotton and linen pigments, resulting in substandard lightfastness. In Comparative Example 9, no stabilizer was added to the third treatment solution, and the extracted free fixative adhered back to the fabric surface, ultimately resulting in substandard lightfastness and a stiff hand feel. In Comparative Example 10, no buffer microcapsules were added to the fourth treatment solution, and the complexation structure between the fixative and the cotton and linen pigments in the weakly acidic state gradually disintegrated under daily washing conditions, resulting in unsatisfactory lightfastness and washability. In Comparative Example 11, the alkalinity of the buffer microcapsules in the fourth treatment solution was too high, which not only failed to further enhance the fixative... The stability of the complex structure of cotton and linen pigments was disrupted, leading to a decrease in lightfastness. In Comparative Example 12, no free radical absorber was added to the fourth treatment solution. The fixing agent complexed on the fabric catalyzed the amino silicone oil to produce a large amount of high-energy active oxygen substances, which destroyed the chromophores that were already stably complexed on the fabric, resulting in unqualified lightfastness. In Comparative Example 13, the free radical absorber was replaced with a UV absorber. The added UV absorber could not prevent the fixing agent complexed on the fabric from catalyzing the amino silicone oil to produce a large amount of high-energy active oxygen substances, resulting in unqualified lightfastness. In Comparative Example 14, the lightfastness of cotton and linen fabrics treated with dimethyl silicone oil was not affected, but the hand feel was not as good as that treated with amino silicone oil.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A processing method for improving the lightfastness of cotton and linen fabrics, characterized in that, Specifically, the steps include the following: Step S1: Mix 20-35 parts of acidic compound enzyme, 20-40 parts of eutectic solvent, 2-4 parts of synergist and 1000 parts of deionized water according to the mass ratio. After stirring thoroughly, the first treatment solution is obtained. Add cotton and linen fabrics to the first treatment solution at a bath ratio of 1:1-3. Keep the fabrics in a dyeing machine at 60℃~80℃ for 120min~180min. Then drain the first treatment solution and wash with clean water. Step S2: Mix 1-3 parts of fixing agent, 50-100 parts of ionic liquid and 1000 parts of deionized water according to the mass ratio, stir evenly to obtain the second treatment solution, and keep the fabric treated in step S1 in the second treatment solution at 40℃~60℃ for 120min~180min at a bath ratio of 1:3-5, and then drain the second treatment solution. Step S3: Take 2-5 parts of the capture agent and 1000 parts of deionized water according to the mass ratio and mix them thoroughly to obtain the third treatment solution. Treat the fabric treated in step S2 in the third treatment solution at a bath ratio of 1:1-3 for 30 min to 60 min. Then add 5-10 parts of stabilizer to the third treatment solution, heat to 30-50℃ and keep warm for 60-120 min. Drain the third treatment solution and wash with clean water. Step S4: Mix 20-50 parts of buffer microcapsules, 30-50 parts of softener, 10-30 parts of free radical absorber, 1-5 parts of emulsifying dispersant and 1000 parts of deionized water according to the mass ratio. After thorough stirring, the fourth treatment solution is obtained. The fabric treated in step S3 is treated in the fourth treatment solution at a bath ratio of 1:1-3 for 30-60 minutes. After that, the fourth treatment solution is drained. The treated fabric is taken out of the dyeing machine and dried to complete the processing.

2. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 1, characterized in that, In step S1, the acidic complex enzyme is one or more of acidic amylase, acidic pectinase, acidic lipase, acidic xylanase, and acidic hemicellulase; the eutectic solvent is choline chloride / lactic acid, choline chloride / citric acid, or choline chloride / malic acid in a molar ratio of 1:1; and the synergist is one or more of rhamnolipid, sophorolipid, and trehalolipid.

3. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 2, characterized in that, In step S1, the concentrations of acidic amylase (5-8 g / L), acidic pectinase (8-12 g / L), acidic lipase (2-4 g / L), acidic xylanase (3-6 g / L), acidic hemicellulase (2-5 g / L), eutectic solvent (20-40 g / L), and synergist (2-4 g / L) are all specified. The pH of the first treatment solution is adjusted to 4-5 using sodium hydroxide.

4. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 1, characterized in that, In step S2, the fixing agent is one or more of cerium chloride, cerium nitrate, cerium sulfate, lanthanum chloride, lanthanum sulfate, lanthanum nitrate, and stannous chloride; the ionic liquid is one or more of 1-butyl-3-methylimidazolium acetate, 1-propyl-3-methylimidazolium acetate, and 1-ethyl-3-methylimidazolium acetate.

5. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 4, characterized in that, In step S2, the concentration of the fixing agent is 1-3 g / L, the concentration of the ionic liquid is 50-100 g / L, and the pH of the second treatment solution is adjusted to 5-6 with acetic acid.

6. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 1, characterized in that, In step S3, the capturing agent is one or more of sodium octanoate, sodium nonanoate, and sodium decanoate; the stabilizer is one or more of methyl-β-cyclodextrin, hydroxypropyl-β-cyclodextrin, and carboxymethyl-β-cyclodextrin.

7. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 6, characterized in that, In step S3, the concentration of the scavenging agent is 2-5 g / L, and the concentration of the stabilizer is 5-10 g / L.

8. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 1, characterized in that, In step S4, the core material of the buffer microcapsule is disodium hydrogen phosphate and potassium dihydrogen phosphate, and the wall material is ethyl cellulose; the softener is amino silicone oil; the free radical absorber is BASF Tinuvin 123-DW, and the emulsifying dispersant is Tween 20.

9. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 8, characterized in that, In step S4, the mass ratio of disodium hydrogen phosphate to potassium dihydrogen phosphate is 2-5:1, the mass ratio of core material to wall material is 1-2:10, the concentration of buffer microcapsules is 20-50 g / L, the concentration of softener is 30-50 g / L, the concentration of free radical absorber is 10-30 g / L, the concentration of emulsifying dispersant is 1-5 g / L, and the drying temperature is 120-150℃.

10. The processing method for improving the lightfastness of cotton and linen fabrics according to claim 1, characterized in that, The cotton-linen fabric has pure cotton yarn in the warp and a blend of cotton and flax fibers in the weft.