A dark dyeing process for bio-based nylon fabric

Abstract

The present invention relates to the technical field of textile dyeing and functional finishing, and specifically discloses a dark dyeing process for bio-based nylon fabrics. The present invention adopts a method of adding tannin natural plant extracts and itaconic acid to the dye bath in sequence after dyeing is completed to perform step-by-step color fixing, which significantly improves the dyeing depth and color fastness of acidic dark dyes on bio-based nylon fabrics, the color fixing rate can reach more than 82%, the dyeing K / S value can reach more than 9, the water washing color fastness can reach more than 4 to 5 levels, the dry rubbing fastness can reach more than 5 levels, and the wet rubbing fastness can reach more than 4 to 5 levels. Moreover, the entire dyeing and color fixing process is completed in the same acidic dark dye solution, which greatly simplifies the production process. Compared with the traditional process multi-bath operation, it is more in line with the development needs of green dyeing and finishing, and provides an efficient and environmentally friendly solution for the industrial dyeing of bio-based nylon fabrics, with good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of textile dyeing and functional finishing, in particular to a dark dyeing process of bio-based nylon fabric. Background Art

[0002] Driven by the concept of sustainable development, bio-based nylon fabrics, derived from renewable resources and characterized by low carbon footprint and environmental friendliness, have shown tremendous potential in the textile industry. Bio-based nylon not only offers the high strength, wear resistance, and corrosion resistance of traditional nylon, but also effectively reduces dependence on petroleum-based raw materials and reduces carbon emissions during production. This aligns with current trends in green consumption and has become a key area of ​​transformation and upgrading for the textile industry.

[0003] However, the dyeing of bio-based nylon fabrics in dark colors faces numerous technical challenges, limiting their application in high-end textiles. Firstly, the molecular structure of bio-based nylon differs from that of traditional petroleum-based nylon. Its unique chemical composition and crystallization properties hinder effective penetration and bonding of dye molecules, making it difficult to achieve the desired dyeing depth and meeting market demand for darker fabrics. Secondly, traditional dyeing processes require high temperatures (>70°C) and strong acidic conditions. This not only places stringent demands on the heat and corrosion resistance of dyeing equipment, significantly increasing equipment costs and maintenance, but can also lead to uneven dyeing due to temperature and pH control errors. Furthermore, conventional dyeing processes require additional post-dyeing fixation treatments, such as the use of cationic fixing agents or high-temperature baking. This multi-step process not only prolongs production cycles, increases energy consumption and labor costs, but can also easily cause dye migration, resulting in poor color fastness in the final product, with wet rubbing fastness typically reaching only around level 3.

[0004] To improve dyeing conditions and effects, the existing technology uses a method of low-temperature plasma pretreatment combined with reactive dye dyeing. Although the dyeing temperature is reduced to 80°C, which alleviates the disadvantages of high-temperature dyeing to a certain extent, this technology introduces expensive equipment investment, increasing production costs by about 30%. At the same time, the complex process flow also reduces production efficiency, making it difficult to achieve large-scale industrial application.

[0005] As consumers' requirements for textile quality and environmental protection continue to increase, the development of a dark dyeing process suitable for bio-based nylon fabrics that achieves high dyeing depth, excellent color fastness, and dyeing under mild conditions has become a technical problem that needs to be urgently solved in the current textile field. Summary of the Invention

[0006] The present invention addresses the challenges of existing dark-dyeing processes for bio-based nylon fabrics, such as harsh process conditions, suboptimal dye depth, low wet rubbing fastness, cumbersome production procedures, and high production costs. This process utilizes a specific natural plant extract of tannins and itaconic acid to synergistically fix the dyed bio-based nylon fabric, achieving efficient dyeing and fixation under mild conditions, significantly improving the dyeing effect. This approach provides a new approach for developing efficient, green dyeing processes for bio-based nylon fabrics.

[0007] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0008] A dark dyeing process for bio-based nylon fabric comprises the following steps:

[0009] S1, dark dyeing of bio-based nylon fabric;

[0010] S2, after dyeing is completed, tannin natural plant extracts and itaconic acid are added to the dye bath in sequence and step by step to perform step-by-step color fixation to obtain a dark bio-based nylon fabric;

[0011] The tannin natural extract is at least one of emblica fruit extract, pomegranate peel extract or gallnut extract.

[0012] Compared with the prior art, the dark dyeing process of bio-based nylon fabric provided by the present invention uses itaconic acid and tannin natural extracts to form a composite color fixing system, wherein the carboxyl group of itaconic acid dissociates into H in the dye bath environment. + , maintain the protonation state of amino groups on the surface of nylon 56 fiber (-NH2 is converted to -NH3 + ), significantly enhancing its binding to acid dyes through electrostatic attraction. On the other hand, the carboxyl groups of itaconic acid can hydrogen bond with the abundant phenolic hydroxyl groups in tannin-based natural plant extracts, forming a dynamic cross-linking network. This dual functionality enables itaconic acid to effectively connect nylon fibers, dye molecules, and natural plant extracts, building a stable dyeing and fixation system that effectively prevents dye molecules from detaching from the fiber surface due to external factors. Tannin-based natural plant extract molecules contain multiple gallic acid structures, providing a large number of hydroxyl active sites. These densely packed hydroxyl groups not only form a multi-level cross-linking network with the carboxyl groups of itaconic acid through hydrogen bonding, but also tightly bind to the dye molecules through van der Waals forces, forming a "molecular coating" on the surface of the dye molecules, effectively restricting their movement and significantly improving color fastness.

[0013] In addition, tannin natural plant extracts are added before itaconic acid, and the rich hydroxyl sites of tannin natural plant extracts are used to initially combine with fabrics and dyes to form a basic color-fixing network; the subsequently added itaconic acid, with its high reactivity and bifunctionality, further cross-links and strengthens the existing network, forming a gradient color-fixing mechanism of "first adsorption fixation-later cross-linking reinforcement"; in addition, the addition of tannin natural plant extracts can play a buffering role in the early stage of the dye bath. With the addition of itaconic acid, this buffering capacity can effectively neutralize the large amount of H released by itaconic acid during the dissociation process. + This prevents damage to the fiber structure caused by low local pH values ​​in the dye bath, while also inhibiting the aggregation of dye molecules in a strong acid environment, ensuring uniform adsorption and fixation of the dye on the fiber surface, significantly improving dyeing uniformity. Compared to adding the dyes simultaneously or in reverse order, this step-by-step addition method significantly improves the fabric's wet rubbing fastness and dyeing uniformity.

[0014] It should be noted that the bio-based nylon fabric described in the present invention is specifically a fabric made of nylon PA56 according to the existing textile process. The present invention does not specifically limit the specific textile process. PA56 fabrics made by traditional textile processes are all suitable for the dyeing process provided by the present invention.

[0015] As a specific embodiment of the present invention, the dark dyeing process of the bio-based nylon fabric comprises the following steps:

[0016] S1, immersing the bio-based nylon fabric in warm water for pre-swelling, and then immersing it in an acidic dark dye solution for dyeing;

[0017] S2, after dyeing is completed, directly add tannin natural plant extract to the acidic dark dark dye solution, let it stand for a first preset time, then continue to add itaconic acid to the acidic dark dark dye solution, let it stand for a second preset time, fix the color at 50°C~60°C, wash with water, and dry to obtain a dark bio-based nylon fabric.

[0018] First, the bio-based nylon fabric is pre-swelled in warm water, which can effectively reduce the crystallinity and density inside the fiber and increase the activity of the fiber molecular chain, which is beneficial to improving the adsorption rate and amount of the dye, so that the dye can be more evenly distributed inside and on the surface of the fiber; after dyeing is completed, tannin natural plant extracts are first added to the acidic dark dye solution, and then itaconic acid is added for color fixation, so that a multi-level hydrogen bond network is formed between the dye, nylon fiber and itaconic acid, which wraps the dye molecules and further enhances the color fixation effect, breaking through the limitation of traditional processes that the wet friction fastness can only reach about level 3.

[0019] In addition, the entire dyeing and fixing process is completed in the same acidic dark dye solution, using a one-bath two-step operation, which avoids the waste of dye and water resource consumption caused by the need to change the dye bath for dyeing and fixing in the traditional process, simplifies the production process and shortens the production cycle; natural plant extracts such as tannin extract, pomegranate peel extract or gallnut extract are derived from renewable plant resources, are green and environmentally friendly, avoid the toxic and harmful residue problems that may be caused by traditional fixing agents, comply with the environmental protection concept of bio-based nylon fabrics, and are easier to achieve large-scale industrial applications, truly realizing high dyeing depth, excellent color fastness and low energy consumption, environmental protection, and low-cost dyeing process, effectively solving the current technical difficulties in dark dyeing of bio-based nylon fabrics.

[0020] Furthermore, the preparation method of the tannin natural plant extract comprises the following steps:

[0021] The natural plant is crushed and added into water, and ultrasonic extraction is performed at 50°C to 70°C for 30min to 50min, and the extract is evaporated to dryness to obtain a natural tannin extract;

[0022] Wherein, the natural plant is at least one of emblica, pomegranate peel or gallnut.

[0023] The preferred extraction method can not only effectively promote the dissolution of tannin components in plants, but also avoid damage to the tannin structure, retaining its active groups (such as phenolic hydroxyl groups) to the greatest extent, laying a good foundation for the subsequent color fixation step.

[0024] Furthermore, the mass ratio of the natural plant to water is 1:(10~20).

[0025] Furthermore, in S1, the temperature of the warm water is 50° C. to 60° C., and the pre-swelling time is 10 min to 15 min.

[0026] Furthermore, in S1, the acidic dark-colored dye solution includes an acidic dark-colored dye and an acidic leveling agent, wherein the added amount of the acidic dark-colored dye is 2% to 3% of the mass of the bio-based nylon fabric, and the concentration of the acidic leveling agent in the acidic dark-colored dye solution is 0.5 g / L to 0.8 g / L.

[0027] For example, the acidic dark color dye can be selected from one of acid black 172, acid blue MR, acid navy blue W-BR or acid jujube red BS.

[0028] For example, the acidic leveling agent can be selected from DM-2260GA (Wuxi Huishan Demei Chemical Co., Ltd.).

[0029] Furthermore, in S1, the pH of the acidic dark dye solution is 4.0-4.5, the bath ratio of dyeing is 1:(20-35), the dyeing temperature is 55°C-65°C, the heating rate is 1°C / min-2°C / min, and the dyeing time is 40min-50min.

[0030] The optimal dyeing conditions allow the dye molecules to be evenly and gradually adsorbed onto the fiber surface and diffuse into the interior, avoiding uneven dyeing and color spots, and significantly improving dyeing uniformity.

[0031] It should be noted that acetic acid is used to adjust the pH of the acidic dark dye solution to 4.0-4.5.

[0032] Furthermore, in S2, the bath ratio of the color fixing is 1:(20-30), and the color fixing time is 20 min-40 min.

[0033] Furthermore, in S2, the amount of the tannin natural plant extract added is 2% to 4% of the mass of the bio-based nylon fabric, and the first preset time is 10 minutes to 20 minutes.

[0034] Furthermore, in S2, the amount of itaconic acid added is 0.5% to 2% of the mass of the bio-based nylon fabric, and the second preset time is 10 minutes to 20 minutes.

[0035] First, add a specific amount of tannin natural plant extract to pre-adjust the pH of the dye solution to weak acidity (close to the isoelectric point of nylon fiber), and then add a specific amount of itaconic acid to further lower the pH to 3.1~3.5, enhance fiber protonation, promote fiber-dye electrostatic bonding, and improve the color fixation effect.

[0036] The present invention also provides a dark-colored bio-based nylon fabric, which is produced by utilizing the dark-colored dyeing process of the bio-based nylon fabric.

[0037] The dark dyeing process for bio-based nylon fabrics provided by the present invention can improve the dyeing depth and dye fastness of dark dyes on bio-based nylon fabrics, with a color fixation rate of more than 82%, a dyeing K / S value of more than 9, a water washing color fastness of more than 4 to 5 levels, a dry rubbing fastness of more than 5 levels, and a wet rubbing fastness of more than 4 to 5 levels. In addition, the color fixation process provided by the present invention uses natural plant extracts as core ingredients, replacing chemical synthetic substances such as cationic color fixatives commonly used in traditional dyeing processes, thereby reducing the environmental pollution risk of the dyeing process from the source; and the entire dyeing and color fixation process is completed in the same acidic dark dye liquor, which greatly simplifies the production process. Compared with the traditional process of multi-bath operation, it is more in line with the development needs of green dyeing and finishing, and provides an efficient and environmentally friendly solution for the industrial dyeing of bio-based nylon fabrics, with good application prospects. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the 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.

[0039] The denim used in the following examples and comparative examples has a density of 480×350 strands / 10 cm and is provided by Wujiang Fuhua Weaving Co., Ltd.

[0040] In the following examples and comparative examples, K / S was measured using a Color i5D colorimeter (X-Rite, USA). The test standard for wash fastness was GB / T 5713-2013; the test standard for dry rubbing fastness was GB / T 3920-2008; and the test standard for wet rubbing fastness was GB / T 3920-2008.

[0041] The fixation rate F is calculated according to the following formula:

[0042] F=E-(A4n4 / A3n3)×100%

[0043] Where:

[0044] F-dyeing fixation rate;

[0045] E-color absorption rate;

[0046] A4-absorbance value of soap boiling residue;

[0047] n4- dilution factor of soap boiling residue;

[0048] A3-absorbance value of standard soap solution;

[0049] n3-dilution factor of standard soap solution.

[0050] The color absorption rate E is calculated according to the following formula:

[0051] E=(1-A2n2 / A1n1)×100%

[0052] Where:

[0053] E-color absorption rate;

[0054] A2-absorbance value of the residual dye solution;

[0055] n2-dilution factor of the residual staining solution;

[0056] A1-absorbance value of standard dye solution;

[0057] n1-dilution factor of standard dye solution.

[0058] The detection wavelength of the above absorbance is 576 nm.

[0059] The acidic leveling agent used in the following examples and comparative examples is DM-2260GA, produced by Wuxi Huishan Demei Chemical Co., Ltd.

[0060] Example 1

[0061] This embodiment provides a dark dyeing process for bio-based nylon fabric, comprising the following steps:

[0062] S1: Bio-based nylon 56 fabric was immersed in 60°C warm water for pre-swelling for 10 minutes, then immersed in a dye solution with a bath ratio of 1:30. The temperature was raised to 60°C at a rate of 1.5°C / min and dyed for 40 minutes. The pH of the dye solution was 4.0 (adjusted with acetic acid). The dye was acid black 172 dye at a concentration of 2% of the fabric weight. The concentration of the acid leveling agent DM-2260GA was 0.6 g / L.

[0063] S2. After dyeing is completed, add emblica extract directly to the dye solution in an amount of 4% of the fabric mass, let it stand for 15 minutes, then continue to add itaconic acid to the dye solution in an amount of 1.5% of the fabric mass, let it stand for 15 minutes, adjust the bath ratio to 1:30, heat to 60℃ for fixing for 30 minutes, wash with cold water, and dry to obtain a dark bio-based nylon fabric.

[0064] The preparation method of the above-mentioned emblica extract comprises the following steps:

[0065] The emblica fruit was crushed and added into water, with the mass ratio of emblica fruit to water being 1:20. The product was extracted by ultrasonic at 60° C. for 40 min, and the extract was evaporated to dryness to obtain the emblica fruit extract.

[0066] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 88.36%, the K / S value was 11.78, the color fastness to washing was level 5, the dry rubbing fastness was level 5, and the wet rubbing fastness was level 5.

[0067] Example 2

[0068] This embodiment provides a dark dyeing process for bio-based nylon fabric, comprising the following steps:

[0069] S1: Bio-based nylon 56 fabric was pre-swelled in 54°C warm water for 15 minutes, then immersed in a dye solution with a bath ratio of 1:25. The temperature was raised to 55°C at a rate of 1°C / min and dyed for 45 minutes. The pH of the dye solution was 4.1 (adjusted with acetic acid). The dye was acid navy blue W-BR at a concentration of 2.2% of the fabric weight. The concentration of the acid leveling agent DM-2260GA was 0.5 g / L.

[0070] S2. After dyeing is completed, add emblica oleracea extract directly to the dye solution in an amount of 2% of the fabric mass, let it stand for 10 minutes, then continue to add itaconic acid to the dye solution in an amount of 2% of the fabric mass, let it stand for 20 minutes, adjust the bath ratio to 1:25, heat to 58°C for fixing for 20 minutes, wash with cold water, and dry to obtain a dark bio-based nylon fabric.

[0071] The preparation method of the above-mentioned emblica extract comprises the following steps:

[0072] The emblica fruit was crushed and added into water, with the mass ratio of emblica fruit to water being 1:10. The product was ultrasonically extracted at 50° C. for 50 min, and the extract was evaporated to dryness to obtain the emblica fruit extract.

[0073] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 86.69%, the K / S value was 9.79, the color fastness to washing was level 4-5, the dry rubbing fastness was level 5, and the wet rubbing fastness was level 4-5.

[0074] Example 3

[0075] This embodiment provides a dark dyeing process for bio-based nylon fabric, comprising the following steps:

[0076] S1: Bio-based nylon 56 fabric was pre-swelled in 58°C warm water for 14 minutes, then immersed in a dye solution with a bath ratio of 1:20. The temperature was raised to 65°C at a rate of 2°C / min and dyed for 50 minutes. The pH of the dye solution was 4.5 (adjusted with acetic acid), the dye was acid red BS, the addition amount was 2.3% of the fabric weight, and the concentration of the acid leveling agent DM-2260GA was 0.8 g / L.

[0077] S2. After dyeing is completed, the gallnut extract is directly added to the dye solution in an amount of 3% of the fabric mass, and the mixture is allowed to stand for 20 minutes. Then, itaconic acid is continued to be added to the dye solution in an amount of 1% of the fabric mass, and the mixture is allowed to stand for 10 minutes. The bath ratio is adjusted to 1:20, and the mixture is heated to 50°C for fixing for 40 minutes. The mixture is then washed with cold water and dried to obtain a dark bio-based nylon fabric.

[0078] The preparation method of the Chinese gallnut extract comprises the following steps:

[0079] The gallnut was crushed and added into water, with the mass ratio of emblica to water being 1:15. The gallnut was extracted by ultrasonic at 70°C for 30 minutes, and the extract was evaporated to dryness to obtain the gallnut extract.

[0080] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 82.72%, the K / S value was 10.01, the color fastness to washing was level 5, the dry rubbing fastness was level 5, and the wet rubbing fastness was level 4-5.

[0081] Example 4

[0082] This embodiment provides a dark dyeing process for bio-based nylon fabric, comprising the following steps:

[0083] S1: Bio-based nylon 56 fabric was pre-swelled in 50°C warm water for 12 minutes, then immersed in a dye solution with a bath ratio of 1:35. The temperature was raised to 63°C at a rate of 1.8°C / min and dyed for 43 minutes. The pH of the dye solution was 4.3 (adjusted with acetic acid). The dye was Acid Blue MR at a concentration of 2.5% of the fabric weight. The concentration of the acid leveling agent DM-2260GA was 0.7 g / L.

[0084] S2. After dyeing is completed, pomegranate peel extract is directly added to the dye solution in an amount of 4% of the fabric mass, and the solution is allowed to stand for 15 minutes. Then, itaconic acid is added to the dye solution in an amount of 0.5% of the fabric mass, and the solution is allowed to stand for 20 minutes. The bath ratio is adjusted to 1:20, and the solution is heated to 53°C for fixing for 25 minutes. The solution is then washed with cold water and dried to obtain a dark bio-based nylon fabric.

[0085] The preparation method of the pomegranate peel extract comprises the following steps:

[0086] The pomegranate peel was crushed and added into water, with the mass ratio of emblica to water being 1:18. The extraction was carried out by ultrasonication at 65°C for 45 minutes, and the extract was evaporated to dryness to obtain the pomegranate peel extract.

[0087] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 84.54%, the K / S value was 9.30, the color fastness to washing was level 5, the dry rubbing fastness was level 5, and the wet rubbing fastness was level 4-5.

[0088] Comparative Example 1

[0089] This comparative example provides a dark dyeing process for bio-based nylon fabric, which is different from Example 1 only in that the order of adding the emblica extract and itaconic acid is changed, and the rest is the same. Specifically, it includes the following steps:

[0090] S1, same as Example 1;

[0091] S2. After dyeing is completed, itaconic acid is directly added to the dye solution in an amount of 1.5% of the fabric mass, and the mixture is allowed to stand for 15 minutes. Then, the emblica extract is continued to be added to the dye solution in an amount of 4% of the fabric mass, and the mixture is allowed to stand for 15 minutes. The bath ratio is adjusted to 1:30, and the mixture is heated to 60°C for fixing for 30 minutes. The mixture is then washed with cold water and dried to obtain a dark bio-based nylon fabric.

[0092] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 81.52%, the K / S value was 8.87, the color fastness to washing was level 4-5, the dry rubbing fastness was level 5, and the wet rubbing fastness was level 4.

[0093] The reason is that itaconic acid first combines with the fiber, but part of the carboxyl groups are monopolized by the fiber. When the remaining carboxyl groups combine with the tannin natural plant extracts added subsequently, the hydrogen bond network density decreases, resulting in a decrease in the dye encapsulation rate, and therefore, a decrease in the color fixation rate and color fastness.

[0094] Comparative Example 2

[0095] This comparative example provides a dark dyeing process for bio-based nylon fabrics. The only difference from Example 1 is that the emblica extract is replaced with an equal amount of a 4% tannic acid aqueous solution. The rest of the process is identical. The process specifically comprises the following steps:

[0096] S1, same as Example 1;

[0097] S2. After dyeing is completed, a 4% tannic acid aqueous solution is directly added to the dye solution in an amount of 4% of the fabric mass, and the mixture is allowed to stand for 15 minutes. Then, itaconic acid is added to the dye solution in an amount of 1.5% of the fabric mass, and the mixture is allowed to stand for 15 minutes. The bath ratio is adjusted to 1:30, and the mixture is heated to 60°C for fixing for 30 minutes. The mixture is then washed with cold water and dried to obtain a dark bio-based nylon fabric.

[0098] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 79.36%, the K / S value was 9.22, the color fastness to washing was 4-5, the dry rubbing fastness was 4-5, and the wet rubbing fastness was 4.

[0099] Comparative Example 3

[0100] This comparative example provides a dark dyeing process for bio-based nylon fabrics. The only difference from Example 1 is that the emblica extract and itaconic acid are replaced with a commercially available acidic dye fixing agent DM-2537 (Wuxi Huishan Demei Chemical Co., Ltd.) with a mass concentration of 4%. The rest of the process is identical, and specifically includes the following steps:

[0101] S1, same as Example 1;

[0102] S2. After dyeing is completed, a commercially available acidic fixing agent DM-2537 with a mass concentration of 4% is directly added to the dye liquor, the amount of which is 5.5% of the fabric mass. The dye liquor is allowed to stand for 15 minutes, the bath ratio is adjusted to 1:30, the temperature is raised to 60°C for fixing for 30 minutes, the dye liquor is washed with cold water, and the dye liquor is dried to obtain a dark bio-based nylon fabric.

[0103] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 75.32%, the K / S value was 9.01, the color fastness to washing was level 4, the dry rubbing fastness was level 4-5, and the wet rubbing fastness was level 3-4.

[0104] Comparative Example 4

[0105] This comparative example provides a dark dyeing process for bio-based nylon fabric. The only difference from Example 1 is that itaconic acid is not added in the fixing step. The rest is identical. Specifically, the process includes the following steps:

[0106] S1, same as Example 1;

[0107] S2, after dyeing is completed, add emblica extract directly to the dye solution, the addition amount is 4% of the fabric mass, let it stand for 15 minutes, adjust the bath ratio to 1:30, heat to 60℃ for fixing for 30 minutes, wash with cold water, and dry to obtain dark bio-based nylon fabric.

[0108] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 81.38%, the K / S value was 9.41, the color fastness to washing was level 4-5, the dry rubbing fastness was level 5, and the wet rubbing fastness was level 4-5.

[0109] Comparative Example 5

[0110] This comparative example provides a dark dyeing process for bio-based nylon fabric, which is different from Example 1 only in that the emblica extract is not added in the color fixing step, and the rest is identical. Specifically, it includes the following steps:

[0111] S1, same as Example 1;

[0112] S2, after dyeing is completed, itaconic acid is directly added to the dye solution in an amount of 1.5% of the fabric mass, and the mixture is allowed to stand for 15 minutes. The bath ratio is adjusted to 1:30, and the mixture is heated to 60°C for 30 minutes for color fixation. The mixture is then washed with cold water and air-dried to obtain a dark bio-based nylon fabric.

[0113] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 80.24%, the K / S value was 10.12, the color fastness to washing was 4-5, the dry rubbing fastness was 4-5, and the wet rubbing fastness was 4.

[0114] Comparative Example 6

[0115] This comparative example provides a dark dyeing process for bio-based nylon fabric, which is different from Example 1 only in that the emblica extract is replaced with the chestnut shell extract, and the rest is the same. Specifically, it includes the following steps:

[0116] S1, same as Example 1;

[0117] S2. After dyeing is completed, chestnut shell extract is directly added to the dye solution in an amount of 4% of the fabric mass, and the solution is allowed to stand for 15 minutes. Then, itaconic acid is added to the dye solution in an amount of 1.5% of the fabric mass, and the solution is allowed to stand for 15 minutes. The bath ratio is adjusted to 1:30, and the solution is heated to 60°C for fixing for 30 minutes. The solution is then washed with cold water and dried to obtain a dark bio-based nylon fabric.

[0118] The preparation method of the chestnut shell extract comprises the following steps:

[0119] The chestnut shell was crushed and added into water, with the mass ratio of emblica to water being 1:20. The extraction was carried out by ultrasonication at 60°C for 40 minutes, and the extract was evaporated to dryness to obtain the chestnut shell extract.

[0120] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 77.46%, the K / S value was 9.28, the color fastness to washing was level 4, the dry rubbing fastness was level 4-5, and the wet rubbing fastness was level 4.

[0121] Comparative Example 7

[0122] This comparative example provides a dark dyeing process for bio-based nylon fabric, which is different from Example 1 only in that the emblica extract is replaced with a mixed plant extract, and the rest is identical. Specifically, it includes the following steps:

[0123] S1, same as Example 1;

[0124] S2. After dyeing is completed, the mixed plant extract is directly added to the dye solution in an amount of 4% of the fabric mass, and the mixture is allowed to stand for 15 minutes. Then, itaconic acid is continued to be added to the dye solution in an amount of 1.5% of the fabric mass, and the mixture is allowed to stand for 15 minutes. The bath ratio is adjusted to 1:30, and the mixture is heated to 60°C for fixing for 30 minutes. The mixture is then washed with cold water and dried to obtain a dark bio-based nylon fabric.

[0125] The preparation method of the mixed plant extract comprises the following steps:

[0126] The cactus, aloe, jade butterfly, rainbow jade and winter beauty are washed, pulped, sieved through 120 meshes to obtain juice; the juice is vacuum freeze-dried to obtain a mixed plant extract.

[0127] The dark bio-based nylon fabric prepared above was tested, and the color fastness was 45.61%, the K / S value was 9.11, the color fastness to washing was level 4, the dry rubbing fastness was level 4-5, and the wet rubbing fastness was level 5.

[0128] In summary, the dark dyeing process for bio-based nylon fabrics provided by the present invention can effectively improve the fixation rate and color fastness of acidic dark dyes, and the dyeing and fixation adopt a one-pot two-step method, which shortens the dyeing time, has strong process controllability, good dyeing repeatability, low wastewater discharge, is clean and environmentally friendly, and has good application prospects.

[0129] 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 or 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 dark dyeing process for bio-based nylon fabrics, characterized in that: The steps include: S1, immersing the bio-based nylon fabric in warm water for pre-swelling, and then immersing it in an acidic dark dye solution for dyeing; S2, after dyeing is completed, directly adding a tannin natural plant extract to the acidic dark dye solution, letting it stand for a first preset time, then continuing to add itaconic acid to the acidic dark dye solution, letting it stand for a second preset time, fixing the color at 50°C to 60°C, washing with water, and drying to obtain a dark bio-based nylon fabric; The tannin natural extract is at least one of emblica extract, pomegranate peel extract or gallnut extract; The acidic dark-color dyeing solution comprises an acidic dark-color dye and an acidic leveling agent, wherein the acidic dark-color dye is selected from one of acid black 172, acid blue MR, acid navy blue W-BR or acid jujube red BS.

2. The dark dyeing process of bio-based nylon fabric according to claim 1, characterized in that: The preparation method of the tannin natural plant extract comprises the following steps: The natural plant is crushed and added into water, and ultrasonic extraction is performed at 50°C to 70°C for 30min to 50min, and the extract is evaporated to dryness to obtain a natural tannin extract; Wherein, the natural plant is at least one of emblica, pomegranate peel or gallnut.

3. The dark dyeing process of bio-based nylon fabric according to claim 2, characterized in that: The mass ratio of the natural plant to water is 1:(10~20).

4. The dark dyeing process of bio-based nylon fabric according to claim 1, characterized in that: In S1, the temperature of the warm water is 50° C. to 60° C., and the pre-swelling time is 10 min to 15 min.

5. The dark dyeing process of bio-based nylon fabric according to claim 1, characterized in that: In S1, the amount of the acidic dark-colored dye added is 2% to 3% of the mass of the bio-based nylon fabric, and the concentration of the acidic leveling agent in the acidic dark-colored dye solution is 0.5 g / L to 0.8 g / L.

6. The dark dyeing process of bio-based nylon fabric according to claim 1, characterized in that: In S1, the pH of the acidic dark dye solution is 4.0-4.5, the dyeing bath ratio is 1:(20-35), the dyeing temperature is 55°C-65°C, the heating rate is 1°C / min-2°C / min, and the dyeing time is 40min-50min.

7. The dark dyeing process of bio-based nylon fabric according to claim 1, characterized in that: In S2, the bath ratio of the color fixing is 1:(20-30), and the color fixing time is 20 min-40 min.

8. The dark dyeing process of bio-based nylon fabric according to claim 1, characterized in that: In S2, the amount of the tannin natural plant extract added is 2% to 4% of the mass of the bio-based nylon fabric, and the first preset time is 10 minutes to 20 minutes.

9. The dark dyeing process of bio-based nylon fabric according to claim 1, characterized in that: In S2, the amount of itaconic acid added is 0.5% to 2% of the mass of the bio-based nylon fabric, and the second preset time is 10 minutes to 20 minutes.