Yellowing-resistant jean fabric and manufacturing method thereof

Abstract

The invention discloses an anti-yellowing jean fabric and a manufacturing method thereof, and belongs to the field of textile, and the method comprises the following steps: soaking warp yarns with a pre-finishing liquid, drying, then carrying out sizing dyeing on the warp yarns, weaving weft yarns and the warp yarns subjected to sizing dyeing to obtain a cloth blank, desizing the cloth blank, and then coating with an after-finishing liquid to obtain the anti-yellowing jean fabric, rutile type nano titanium dioxide is dispersed in the pre-finishing liquid; the after-finishing liquid contains a seaweed extract, an olive leaf extract, a green tea leaf extract, a butterfly bean flower extract and nano cellulose. According to the invention, the warps are covered with rutile crystal form nano titanium dioxide before being dyed with indigo, ultraviolet rays are scattered by virtue of high refractive index, the oxidative degradation of indigo dye under illumination is reduced, and the fabric is coated with natural extracts with oxidation resistance, so that the fabric can tolerate natural oxidation; and the inner and outer defense lines can jointly inhibit yellowing of the jean fabric.

Description

Technical Field

[0001] This invention relates to a yellowing-resistant denim fabric and its manufacturing method, belonging to the textile field. Background Technology

[0002] Traditional denim fabric uses pure cotton yarn dyed with indigo for the warp and undyed pure cotton yarn for the weft. Due to the properties of indigo dye and its bonding with cotton fibers, a significant amount of loose dye remains on the surface of the dyed yarn. When stored naturally, denim fabric oxidizes in the air, leading to yellowing and severely affecting the garment's appearance. Current methods primarily focus on anti-yellowing treatments, but existing anti-yellowing solutions are not very effective. Denim fabric treated with existing anti-yellowing solutions is still relatively prone to yellowing due to natural oxidation during transportation and storage. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a yellowing-resistant denim fabric and its manufacturing method, resulting in denim fabric that is less prone to yellowing.

[0004] The technical solution adopted by this invention to solve its technical problem is: A method for manufacturing yellowing-resistant denim fabric includes the following steps: impregnating warp yarns with a pre-treatment solution, drying the warp yarns and then sizing and dyeing them, weaving a fabric blank with weft yarns and the sizing and dyed warp yarns, desizing the fabric blank, and then coating it with a finishing solution to obtain the yellowing-resistant denim fabric. The pretreatment solution contains rutile nano-titanium dioxide dispersed in it. The finishing solution contains seaweed extract, olive leaf extract, green tea leaf extract, butterfly pea flower extract, and nanocellulose.

[0005] When the finishing solution impregnates the warp yarns, nano-titanium dioxide penetrates into the cotton fibers, forming hydrogen bonds with the hydroxyl groups on the fiber surface, thus constructing a physical barrier within the fiber. Rutile-type nano-titanium dioxide can scatter ultraviolet light due to its high refractive index, reducing the oxidative degradation of indigo dye under light. Simultaneously, nano-titanium dioxide also possesses a certain ability to photocatalytically decompose pollutants.

[0006] The finishing solution exhibits strong antioxidant activity, capturing free radicals and preventing the oxidation of indigo dye. Nanocellulose acts as a bridge in this process: its high specific surface area and film-forming properties help the extract to be uniformly dispersed in the coating, and it binds to the fibers through hydrogen bonds, enhancing the density of the coating.

[0007] Furthermore, the content of the rutile nano-titanium dioxide in the pretreatment solution is 2wt%~5wt%.

[0008] When the content is below 2wt%, the UV shielding efficiency decreases, and some fiber areas may be exposed to light, leading to localized yellowing. When the content is above 5wt%, the nanoparticles tend to agglomerate, clogging the fiber gaps, affecting the penetration of the finishing solution and subsequent sizing and dyeing effects, and even causing warp stiffness. Within the range of 2wt% to 5wt%, nano-titanium dioxide can be uniformly dispersed in the finishing solution and penetrate into the microporous structure of cotton fibers through Brownian motion.

[0009] Furthermore, the particle size of the rutile nano-titanium dioxide is between 5 nm and 20 nm.

[0010] Particles of this size can penetrate the amorphous regions of cotton fibers. When irradiated with ultraviolet light, these particles act as scattering points, converting ultraviolet energy into heat energy and reducing the oxidation of indigo dye. Simultaneously, this particle size helps enhance wetting uniformity. Furthermore, the smaller particle size allows for high coverage with lower titanium dioxide content, avoiding the increase in fiber stiffness caused by excessive titanium dioxide dosage.

[0011] Furthermore, the pretreatment solution also contains 20wt%~40wt% nanocellulose, 5wt%~10wt% silane coupling agent, 2wt%~5wt% dispersant, and the balance is water.

[0012] Nanocellulose can increase solution viscosity and control the wetting rate, allowing titanium dioxide to adhere uniformly to the warp yarns. However, excessive dosage makes the solution too viscous, hindering penetration into the fiber interior. Within a suitable dosage range, nanocellulose easily embeds itself into fiber gaps, enhancing the bond between the warp yarns and the pre-finishing solution. Furthermore, the silane coupling agent acts as a bridge, resolving the compatibility issue between titanium dioxide and the fiber interface and reducing the risk of shedding during subsequent sizing and desizing. The dispersant stabilizes the colloidal system through electrostatic repulsion, synergistically working with the steric hindrance effect of nanocellulose to ensure uniform dispersion of titanium dioxide in the finishing solution.

[0013] Furthermore, the warp yarn is a blended yarn consisting of 40wt%~60wt% cotton fiber and 40wt%~60wt% viscose fiber.

[0014] Cotton fiber is a commonly used material in traditional denim fabrics. Its surface is rich in hydroxyl groups, making it easy to combine with nano-titanium dioxide and nano-cellulose in the finishing solution. However, it easily swells after absorbing moisture, potentially clogging the finishing solution channels. Viscose fiber, a type of regenerated cellulose, has stronger moisture absorption and an amorphous structure (compared to the higher crystallinity of cotton fiber), which facilitates rapid penetration of the finishing solution. Furthermore, when applying the finishing solution, the smooth surface of viscose fiber promotes uniform coating spread, while the rough surface of cotton fiber enhances coating adhesion.

[0015] Furthermore, prior to the step of impregnating the warp yarn with the pre-treatment solution, the warp yarn is treated with ozone.

[0016] Furthermore, the warp yarns and the weft yarns are interwoven in a twill pattern. The weft yarns include first and second weft yarns arranged side by side. The second weft yarn is hollow porous polyester, and the first weft yarn is a polyester tow. The polyester tow includes first polyester filaments with a "rice" - shaped radial cross - section and second polyester filaments with a "cross" - shaped radial cross - section. The ratio of the number of the first polyester filaments to the number of the second polyester filaments is 3:2.

[0017] Traditional denim fabrics are interwoven in a twill pattern, making the warp yarn floats longer, with a large exposed area, and being vulnerable to light and oxidation. However, the special structure of the weft yarns can compensate for this defect. As the second weft yarn, the hollow porous polyester has pores serving as micro - air - flow channels, accelerating the air exchange inside and outside the fabric and reducing the accumulation of local heat and humidity. The "rice" - shaped and "cross" - shaped polyester filaments of the first weft yarn form many tiny gaps through the stacking of cross - sectional shapes, facilitating the diffusion by capillary action. For example, during the coating stage, the post - finishing liquid can flow along the gaps of the weft yarns, covering the exposed areas of the warp yarns and reducing the protection dead angles. When worn, the moisture - guiding ability of the weft yarns and the hydrophilicity of the warp yarns form a humidity gradient, helping the moisture migrate outwards and also playing a role in reducing the accumulation of local heat and humidity.

[0018] Furthermore, the preparation steps of the seaweed extract, the olive leaf extract, and the green tea leaf extract include: respectively drying seaweed, olive leaves, and green tea leaves at 65°C for 10 h, then cutting and pulverizing them into powders, extracting one weight part of the powder with two weight parts of 75% alcohol at 75°C for 3.5 h, removing the insoluble substances, and concentrating the liquid to one - half to one - fourth of the original volume to obtain the seaweed extract, the olive leaf extract, and the green tea leaf extract respectively; Furthermore, the preparation steps of the butterfly pea flower extract include: drying the petals of the butterfly pea flower at 65°C for 10 h, then cutting and pulverizing them into powders, adding them to a polyethylene glycol solution with a material - to - liquid ratio of 1:20 - 30, performing ultrasonic extraction at 50°C - 70°C for 1 h - 2 h, and centrifuging the extract to obtain the supernatant, which is the butterfly pea flower extract; the polyethylene glycol concentration of the polyethylene glycol solution is 0.08 g / ml - 0.3 g / ml, the ultrasonic power is 100 W - 180 W, and the polyethylene glycol is preferably PEG200.

[0019] Furthermore, the post - finishing liquid includes, by mass, 20 - 30 parts of the seaweed extract, 30 - 40 parts of the olive leaf extract, 15 - 20 parts of the green tea leaf extract, 15 - 20 parts of the butterfly pea flower extract, 10 - 15 parts of the nanocellulose, and 4 - 8 parts of the cross - linking agent.

[0020] In a second aspect, the present application provides a yellowing - resistant denim fabric prepared by the method for manufacturing a yellowing - resistant denim fabric described in the first aspect.

[0021] The beneficial effects of this invention are as follows: Internally, this invention makes the warp yarns covered with rutile-type nano-titanium dioxide before dyeing with indigo. Relying on the high refractive index to scatter ultraviolet rays, it reduces the oxidative degradation of indigo dye under light. Externally, the fabric is also coated with natural extracts with antioxidant capabilities, which enables the fabric to withstand natural oxidation. The dual defense of the inside and outside can jointly inhibit the yellowing of denim fabric.

[0022] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0023] Figure 1 This is a structural schematic diagram of a yellowing-resistant denim fabric provided in an embodiment of this application.

[0024] Figure 2 This is a schematic diagram of the structure of a first weft yarn provided in an embodiment of this application.

[0025] Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0026] Figure labels: 1, warp yarn; 21, first weft yarn; 211, first polyester filament; 212, second polyester filament; 22, second weft yarn. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this invention.

[0028] It should be understood that, without conflict, any and all embodiments of the present invention can be combined with technical features of any other embodiment or multiple other embodiments to obtain other embodiments. The present invention includes such combinations to obtain other embodiments.

[0029] Unless otherwise specified, all technical and scientific terms used herein have the standard meaning in the field to which the claimed subject matter pertains. Where multiple definitions exist for a term, the definition herein shall prevail.

[0030] This application provides a method for manufacturing yellowing-resistant denim fabric, the steps of which include: soaking the warp yarns with a pre-treatment liquid, drying the warp yarns and then sizing and dyeing them, weaving a fabric blank with the weft yarns and the sizing and dyed warp yarns, desizing the fabric blank, coating it with a post-treatment liquid, and obtaining yellowing-resistant denim fabric. Rutile nano-titanium dioxide is dispersed in the pre-treatment solution; The finishing solution contains seaweed extract, olive leaf extract, green tea leaf extract, butterfly pea flower extract, and nanocellulose.

[0031] The pre-finishing and post-finishing solutions work together to form a dual defense against ultraviolet radiation and free radical scavenging. For example, when the nano-titanium dioxide in the pre-finishing solution generates a small amount of reactive oxygen species due to ultraviolet scattering, the polyphenols in the post-finishing solution can promptly neutralize these oxidation byproducts, preventing them from attacking indigo dye molecules. Furthermore, the addition of nanocellulose optimizes the breathability of the coating, preventing a decrease in fabric comfort due to complete sealing.

[0032] Overall, this method addresses the issue of limited effectiveness in traditional anti-yellowing finishing solutions by applying finishing solutions sequentially and using complementary components. The synergistic effect of rutile nano-titanium dioxide and natural extracts enhances anti-yellowing performance, and the raw materials used are more environmentally friendly than existing anti-yellowing agents.

[0033] Specifically, the content of rutile nano-titanium dioxide in the pretreatment solution is 2wt%~5wt%.

[0034] The barrier formed by nano-titanium dioxide within the fiber does not completely seal the fiber pores, allowing the finishing solution to partially penetrate during the coating stage. While titanium dioxide may generate reactive oxygen species under UV excitation, antioxidants in the finishing solution (such as catechins from green tea extract) can neutralize these oxides in situ, preventing them from diffusing into the dyed areas. Titanium dioxide scatters most UV radiation, reducing the risk of photodegradation of the extract, while the extract captures residual oxidants, extending the overall yellowing resistance lifespan. If the content is too low, the natural extract bears a greater protective burden, potentially accelerating coating aging; if the titanium dioxide content is too high, fiber breathability may decrease, affecting fabric comfort.

[0035] Preferably, the particle size of rutile nano-titanium dioxide is between 5 nm and 20 nm.

[0036] When the particle size is less than 5 nm, the quantum effect of nano-titanium dioxide is significant, and the photocatalytic activity may be enhanced, which may promote the oxidation reaction and exacerbate yellowing. At the same time, excessively small particle size is prone to particle agglomeration, reducing dispersibility. When the particle size is greater than 20 nm, the ultraviolet scattering efficiency decreases (according to Mie scattering theory, scattering efficiency is inversely proportional to particle size), and the particles have difficulty penetrating the fiber micropores (the micropore diameter of cotton fibers is about 10 nm to 50 nm).

[0037] The pretreatment solution also contains 20wt%~40wt% nanocellulose, 5wt%~10wt% silane coupling agent, 2wt%~5wt% dispersant, and the balance is water. The dispersant can be selected from dispersant MF (Shandong Jinqianrun New Material Co., Ltd.), dispersant 5040 (Qingdao Enze Chemical Co., Ltd.), etc.

[0038] Nanocellulose has the characteristics of large specific surface area and high reactivity, and is easily compatible with cotton fiber. It provides more loading sites for nano-titanium dioxide through hydrogen bonding. At the same time, silane coupling agent can act as a bridge to connect the components, making the combination more stable.

[0039] Furthermore, when the particle size of nano-titanium dioxide is in the range of 5nm to 20nm, the particles have a high specific surface area (up to 150 m² / g), which makes it easy to form a stable colloid with the dispersant in the pretreatment solution through electrostatic interaction, thus preventing sedimentation.

[0040] The pre-finishing solution has a high dispersed phase content. The preparation steps are as follows: First, prepare an aqueous dispersion of nanocellulose. Add a dispersant (such as polyacrylate) to the nanocellulose dispersion and mix well. Then, slowly add nano-titanium dioxide powder while stirring at 1000 rpm to 1500 rpm for 20 to 40 minutes. Separately, pre-hydrolyze a silane coupling agent (such as an aminosilane type). While continuously stirring, slowly add the hydrolyzed silane coupling agent. Using this preparation sequence ensures that the pre-finishing solution with a high dispersed phase content is evenly dispersed, which is beneficial for improving the efficiency of wetting the warp yarn.

[0041] In some embodiments, the warp yarn is a blended yarn consisting of 40wt% to 60wt% cotton fiber and 40wt% to 60wt% viscose fiber.

[0042] The high hygroscopicity of viscose fibers allows the finishing solution to preferentially wet their amorphous regions, carrying titanium dioxide particles deep into the fiber interior. During the sizing and dyeing process, the warp yarns with the evenly applied finishing solution ensure a more uniform distribution of indigo dye, avoiding inconsistent surface floating of color. High local floating color is more likely to cause yellowing in those areas.

[0043] Preferably, the warp yarns are treated with ozone before the step of impregnating the warp yarns with the pre-treatment solution.

[0044] Ozone is a strong oxidant that can attack the cellulose chains of cotton and viscose fibers, oxidize some hydroxyl groups to carboxyl groups, increase the hydrophilicity and negative charge of the fiber surface. This modification makes the pre-treatment liquid more permeable. The carboxyl groups form stronger hydrogen bonds with the hydroxyl groups on the surface of nano-titanium dioxide, increasing the loading amount of titanium dioxide. The negatively charged surface can also electrostatically attract some positively charged silane coupling agents, enhancing the bonding strength. Ozone treatment can also etch micropores on the fiber surface, providing anchoring sites for nano-titanium dioxide and constructing a more stable protective layer. Viscose fibers are more easily oxidized by ozone, and the cotton fibers in the blend are beneficial to prevent yarn embrittlement. After treatment, the pre-treatment liquid can evenly cover the fibers, reducing the protection blind spots.

[0045] Refer to Figure 1 , the warp yarn 1 and the weft yarn are interwoven in a twill pattern. The weft yarn includes a first weft yarn 21 and a second weft yarn 22 arranged side by side. The second weft yarn is hollow porous polyester, and the first weft yarn is a polyester tow. Refer to Figure 2 and Figure 3 , the polyester tow includes a first polyester filament 211 with a "rice" - shaped radial cross - section and a second polyester filament 212 with a "cross" - shaped radial cross - section. The number ratio of the first polyester filament 211 to the second polyester filament 212 is 3:2.

[0046] From Figure 3 it can be seen that with this shape and arrangement ratio, there are many gaps between the polyester tows. These gaps can quickly conduct moisture through capillary action, accelerating the relief of the hot and humid state when people wear denim fabrics, which is beneficial to reducing yellowing during daily wear.

[0047] Specifically, the preparation steps of the seaweed extract include: drying the seaweed at 65 °C for 10 h, then cutting and crushing it into powder, extracting one weight part of the powder with two weight parts of 75% alcohol at 75 °C for 3.5 h, removing the insoluble substances, and concentrating the liquid to one - half to one - quarter of the original volume to obtain the seaweed extract.

[0048] The preparation steps of the olive leaf extract include: drying the olive leaves at 65 °C for 10 h, then cutting and crushing them into powder, extracting one weight part of the powder with two weight parts of 75% alcohol at 75 °C for 3.5 h, removing the insoluble substances, and concentrating the liquid to one - half to one - quarter of the original volume to obtain the olive leaf extract.

[0049] The preparation steps of the green tea leaf extract include: drying the green tea leaves at 65 °C for 10 h, then cutting and crushing them into powder, extracting one weight part of the powder with two weight parts of 75% alcohol at 75 °C for 3.5 h, removing the insoluble substances, and concentrating the liquid to one - half to one - quarter of the original volume to obtain the green tea leaf extract.

[0050] The preparation steps of butterfly pea flower extract include: drying butterfly pea flower petals at 65℃ for 10h, then cutting and crushing them into powder, adding them to a polyethylene glycol (average molecular weight 200) solution at a material-to-liquid ratio of 1:20~30, and extracting them by ultrasonication (100W~180W) at 50℃~70℃ for 1h~2h to obtain butterfly pea flower extract; the polyethylene glycol concentration of the polyethylene glycol solution is 0.08g / ml~0.3g / ml.

[0051] Seaweed, olive leaves, and green tea leaves are dried at 65℃ for 10 hours to remove moisture, prevent hydrolysis during extraction, and avoid polyphenol loss due to high temperatures. They are then pulverized into powder to increase the specific surface area and improve extraction efficiency. Polyethylene glycol enhances the solubility of butterfly pea flower extract, and combined with ultrasonic cavitation to disrupt cell walls, it accelerates release. These methods ensure the extract has high antioxidant capacity and better compatibility with nanocellulose in the finishing solution.

[0052] Specifically, the finishing solution, by weight, includes 20-30 parts seaweed extract, 30-40 parts olive leaf extract, 15-20 parts green tea extract, 15-20 parts butterfly pea flower extract, 10-15 parts nanocellulose, and 4-8 parts crosslinking agent. The different extracts work synergistically, maximizing their overall effectiveness, resulting in a coating with good adhesion to the fabric and resistance to cracking.

[0053] Crosslinking agents can be, for example, end-capped isocyanate resins (water resistant), such as aliphatic end-capped isocyanate crosslinking agents, which have strong penetration properties into fibers and can be mixed with various auxiliaries to improve the wash resistance of the coating and make it bond firmly; crosslinking agents can also be environmentally friendly crosslinking agents such as JL-92 (Suzhou Jinyunlai Textile Auxiliaries Co., Ltd.) and SaC-100 (Shanghai Youen Chemical Co., Ltd.), etc.

[0054] Combining the above-mentioned optimized technologies, the nano-titanium dioxide, silane coupling agent, and fiber are more stably bonded under the action of nano-cellulose, providing excellent scattering ability. Combined with natural antioxidant extracts, this effectively forms a protective film on the fabric, working with nano-titanium dioxide to inhibit yellowing of denim fabric during storage and transportation. After garment production, the finishing solution formula improves the coating's wash resistance and prolongs its antioxidant effect. When the body sweats, the twill denim sole quickly wicks away moisture, accelerating the removal of damp heat and moisture, which helps inhibit yellowing after wearing.

[0055] Example 1 The warp yarns are soaked in a pre-treatment solution, dried, and then sized and dyed. The weft yarns and the sized and dyed warp yarns are woven into a fabric in a three-up-one-down twill pattern. After the fabric is desized, it is coated with a finishing solution and dried to obtain a yellowing-resistant denim fabric.

[0056] The pretreatment solution consists of: 20 wt% nanocellulose (Jinan Shengquan Group Co., Ltd.), 5 wt% silane coupling agent (KH560), 2 wt% dispersant (Qingdao Enze Chemical Co., Ltd.), 2 wt% rutile nano titanium dioxide, and the balance being water.

[0057] The finishing solution consists of: 30 parts seaweed extract, 30 parts olive leaf extract, 15 parts green tea extract, 20 parts butterfly pea flower extract, 10 parts nanocellulose (Jinan Shengquan Group Co., Ltd.), 4 parts crosslinking agent (TANALINK PCI 01), and 15 parts water.

[0058] Comparative Example 1 The difference from Example 1 is that the finishing solution consists of: 30 parts seaweed extract, 40 parts olive leaf extract, 10 parts nanocellulose, 4 parts crosslinking agent, and 15 parts water.

[0059] Comparative Example 2 The difference from Example 1 is that the finishing solution consists of: 60 parts seaweed extract, 10 parts nanocellulose, 4 parts crosslinking agent, and 15 parts water.

[0060] Comparative Example 3 The difference from Example 1 is that the finishing solution consists of: 30 parts seaweed extract, 30 parts olive leaf extract, 20 parts green tea extract, 10 parts nanocellulose, 4 parts crosslinking agent, and 15 parts water.

[0061] Comparative Example 4 The difference from Example 1 is that the finishing solution consists of: 30 parts seaweed extract, 10 parts nanocellulose, 4 parts crosslinking agent, and 15 parts water.

[0062] According to GB / T 30159.1-2013 "Textiles - Testing and Evaluation of Stain Resistance - Part 1: Stain Resistance", the stain resistance levels were evaluated based on the stain resistance grades, and the stain resistance grades of the fabrics in the examples and comparative examples were assessed. The ABTS free radical decolorization method was used to test the antioxidant properties of the fabrics. According to the national standard GB / T 29778—2013 "Textiles - Tests for Color Fastness - Evaluation of Potential Phenolic Yellowing", the anti-yellowing tests were conducted on the fabrics in the examples and comparative examples. The results are shown in Table 1 below.

[0063] Table 1

[0064] Therefore, the embodiments of this application have excellent antioxidant activity and anti-yellowing ability, and can resist natural oxidation during storage and transportation.

[0065] In this application, a specific sequence is employed to avoid damage to the finishing solution from the chemical environment of sizing and dyeing, while ensuring the stability of the pre-finishing solution. If the finishing solution is applied before desizing, the chemical environment of sizing and dyeing can easily cause the natural extracts in the finishing solution to lose their antioxidant activity. Applying the finishing solution after desizing avoids these chemical interferences, ensuring the full performance of the antioxidant properties of the natural extracts and forming a stable coating with nanocellulose. The pre-finishing solution is applied and dried before sizing and dyeing, and its components (such as rutile nano-titanium dioxide) have high chemical activity. The nanocellulose and silane coupling agent form a cross-linked network after drying, firmly adhering to the fiber surface and interior, and are not significantly affected by sizing and dyeing or desizing. However, if the pre-finishing solution is applied after sizing and dyeing or desizing, the nano-titanium dioxide is not easy to bind to the internal fibers and is more likely to fall off during subsequent use. In this application, after desizing to remove surface impurities, the finishing solution can form a uniform coating, forming a continuous protective system with the pre-finishing solution. The pre-finishing solution remains intact, and the finishing solution forms a dense film on the clean surface, improving wash resistance.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for manufacturing yellowing-resistant denim fabric, characterized in that the steps include... Comprising: Soaking the warp yarns with a pre-finishing solution, sizing and dyeing the warp yarns after drying, weaving a greige fabric with the weft yarns and the sized and dyed warp yarns, desizing the greige fabric, and coating it with a post-finishing solution to obtain the yellowing-resistant denim fabric; Rutile-type nano titanium dioxide is dispersed in the pre-finishing solution; The post-finishing solution contains seaweed extract, olive leaf extract, green tea leaf extract, butterfly pea flower extract and nano cellulose.

2. The method for manufacturing yellowing-resistant denim fabric according to claim 1, characterized in that, The content of the rutile-type nano titanium dioxide in the pre-finishing solution is 2wt% - 5wt%.

3. The method for manufacturing yellowing-resistant denim fabric according to claim 2, characterized in that, The particle size of the rutile-type nano titanium dioxide is 5nm - 20nm.

4. The method for manufacturing yellowing-resistant denim fabric according to claim 2, characterized in that, The pre-finishing solution further contains 20wt% - 40wt% of nano cellulose, 5wt% - 10wt% of silane coupling agent, 2wt% - 5wt% of dispersant, and the balance is water.

5. The method for manufacturing yellowing-resistant denim fabric according to claim 1, characterized in that, The warp yarns are a blended yarn with 40wt% - 60wt% of cotton fiber and 40wt% - 60wt% of viscose fiber.

6. The method for manufacturing yellowing-resistant denim fabric according to claim 5, characterized in that, Before the step of soaking the warp yarns with the pre-finishing solution, the warp yarns are treated with ozone.

7. The method for manufacturing yellowing-resistant denim fabric according to claim 1, characterized in that, The warp yarns and the weft yarns are interwoven in a twill pattern. The weft yarns include a first weft yarn and a second weft yarn arranged side by side. The second weft yarn is hollow porous polyester, and the first weft yarn is a polyester filament bundle. The polyester filament bundle includes a first polyester filament with a "rice" - shaped radial cross-section and a second polyester filament with a "cross" - shaped radial cross-section. The number ratio of the first polyester filament to the second polyester filament is 3:

2.

8. The method for manufacturing yellowing-resistant denim fabric according to claim 1, characterized in that, The preparation steps of the seaweed extract, the olive leaf extract, and the green tea leaf extract include: respectively drying seaweed, olive leaves, and green tea leaves at 65°C for 10h, then cutting and pulverizing them into powders, extracting one weight part of the powder with two weight parts of 75% alcohol at 75°C for 3.5h, removing insoluble substances, and concentrating the liquid to one-half to one-fourth of the original volume to obtain the seaweed extract, the olive leaf extract, and the green tea leaf extract respectively; The preparation steps of the butterfly pea flower extract include: drying the petals of butterfly pea flowers at 65°C for 10h, then cutting and pulverizing them into powders, adding them to a polyethylene glycol solution with a material-liquid ratio of 1:20 - 30, and performing ultrasonic extraction at 50°C - 70°C for 1h - 2h, centrifuging to take the supernatant to obtain the butterfly pea flower extract; the polyethylene glycol concentration of the polyethylene glycol solution is 0.08g / ml - 0.3g / ml.

9. The method for manufacturing yellowing-resistant denim fabric according to claim 8, characterized in that, The post-finishing solution includes 20 parts - 30 parts of the seaweed extract, 30 parts - 40 parts of the olive leaf extract, 15 parts - 20 parts of the green tea leaf extract, 15 parts - 20 parts of the butterfly pea flower extract, 10 parts - 15 parts of the nano cellulose, and 4 parts - 8 parts of a crosslinking agent by mass.

10. A yellowing-resistant denim fabric, characterized in that, Obtained by the method for manufacturing a yellowing-resistant denim fabric according to any one of claims 1 to 9.

Images