A method for dyeing with vat dyes in an overflow dyeing machine

Abstract

This invention provides a method for dyeing with vat dyes in an overflow dyeing machine. The use of a dye premix significantly improves dyeing performance. The cationic properties of modified cationic starch electrostatically adsorb onto fabric fibers, allowing the coated dye particles to quickly and evenly adhere to the fabric surface. This avoids localized color differences caused by uneven dye dispersion in the dye bath, and the water flow impact in overflow dyeing prevents localized dye aggregation, effectively improving dyeing uniformity and ensuring consistent dyeing results for the same batch of fabrics. The stable structure formed by the cross-linking of modified cationic starch and vat dye forms a protective film on the fabric fiber surface after color fixation, enhancing the binding stability between the dye and fiber, reducing damage to dye molecules from external factors such as light, improving the dye's lightfastness and the fabric's sunlight fastness. Its film-forming properties also make the dye and fiber bond more firmly, preventing fading.

Description

Technical Field

[0001] This invention relates to the field of textile technology, and more specifically to a method for using vat dyes in an overflow dyeing machine. Background Technology

[0002] Vat dyes, due to their bright colors, complete color spectrum, and excellent color fastness, have become a widely used type of dye in the textile printing and dyeing industry, especially suitable for dyeing cellulosic fiber fabrics, and occupy an important position in the production of high-quality textile fabrics. Overflow dyeing machines, with their advantages of smooth fabric flow, gentle dyeing process, and minimal fabric damage, are commonly used dyeing equipment in the textile printing and dyeing industry. Combining vat dyes with overflow dyeing machines has become an important development direction for improving the dyeing quality and production efficiency of textile fabrics, and has also received widespread attention and research within the industry.

[0003] Currently, there are existing dyeing processes in the industry that utilize vat dyes in overflow dyeing machines. Generally, vat dyes are mixed with various auxiliaries, and then the pre-treated fabric is dyed in the overflow dyeing machine. Some processes add starch-based substances as dyeing auxiliaries to improve the bonding effect between the dye and the fabric. During the dyeing operation, process parameters such as temperature and liquor ratio are controlled, along with the addition of leveling agents and oxidizing agents to complete the dyeing and fixing processes. The overall process revolves around the core steps of vat dye reduction, dyeing, and oxidative fixing, with parameters adjusted to suit the operating characteristics of the overflow dyeing machine.

[0004] However, existing overflow dyeing processes for vat dyes still have many technical shortcomings. On the one hand, directly mixed dye systems are prone to uneven dyeing during overflow dyeing, resulting in color differences in fabrics dyed in the same batch and making it difficult to ensure the consistency of dyed products. This is related to the poor binding effect between the dyeing auxiliaries and dyes, and the poor dispersion stability of dyes in the dye bath. On the other hand, fabrics dyed using existing processes exhibit poor lightfastness, easily fading and discoloring after sun exposure. The binding stability between the dye and the fabric fibers is insufficient, failing to meet the lightfastness requirements of high-quality textile fabrics. Furthermore, traditional starch-based dyeing auxiliaries, due to the lack of targeted modification, have poor compatibility with vat dyes, making it difficult to effectively improve dyeing results. This is also a significant factor restricting the application of vat dyes in overflow dyeing machines.

[0005] In conclusion, a new technical solution is urgently needed to address the problems existing in the current technology. Summary of the Invention

[0006] Based on this, the present invention provides a method for dyeing with vat dyes in an overflow dyeing machine. The use of a dye premix significantly improves dyeing performance. The cationic properties of modified cationic starch generate electrostatic adsorption with fabric fibers, allowing the coated dye particles to quickly and uniformly adhere to the fabric surface. This avoids local color differences caused by uneven dye dispersion in the dye bath, and the water flow impact in overflow dyeing prevents local dye aggregation, effectively improving dyeing uniformity and ensuring consistent dyeing results for the same batch of fabrics. The stable structure formed by the cross-linking of modified cationic starch and vat dye forms a protective film on the fabric fiber surface after color fixation, enhancing the binding stability between the dye and fiber, reducing damage to dye molecules from external factors such as light, improving the dye's lightfastness and the fabric's light fastness. Its film-forming properties also make the dye and fiber bond more firmly, preventing fading.

[0007] One object of the present invention is to provide a method for dyeing with vat dyes in an overflow dyeing machine, comprising the following steps: S1. Disperse cationic starch in isopropanol solution, add sodium hydroxide to alkalize, then add allyl chloride and heat and stir to react, to obtain cationic starch containing double bonds; S2. The double-bonded cationic starch, acrylic acid, and hydroxy acrylate are blended together, an initiator is added, and the mixture is heated under inert gas protection to obtain modified cationic starch. S3. The modified cationic starch, vat dye and crosslinking agent are blended and crosslinked to obtain a dye premix; S4. Remove the oil from the fabric to be dyed, place it in an overflow dyeing machine, add the dye premix and leveling agent and perform overflow dyeing to obtain the pre-dyed fabric. S5. Add dyeing auxiliaries to the pre-dyed fabric, heat it, polish it, and dry it to obtain the dyed fabric.

[0008] Further, in step S1, the mass ratio of the cationic starch to allyl chloride is 100:(1-3).

[0009] Furthermore, in step S1, the heating temperature is 30-40°C.

[0010] Further, in step S2, the mass ratio of the double-bonded cationic starch, acrylic acid, and hydroxy acrylate is 10:(0.1-1):(0.5-1.5).

[0011] Furthermore, in step S2, the heating temperature is 60-80℃.

[0012] Further, in step S3, the mass ratio of the modified cationic starch, vat dye, and crosslinking agent is 10:(0.1-1):(0.01-0.1).

[0013] Further, in step S3, the crosslinking agent is selected from one or more of glyoxal and glutaraldehyde.

[0014] Further, in step S4, the leveling agent is selected from one or more of anionic surfactants or nonionic surfactants.

[0015] Furthermore, in step S5, the dyeing auxiliary agent is selected from one or more of oxidizing agents, dispersants, chelating agents, and soaping agents.

[0016] Furthermore, in step S5, the oxidant includes a weak oxidant and a strong oxidant; the weak oxidant includes an organic oxidant; and the strong oxidant includes hydrogen peroxide.

[0017] The present invention has the following beneficial effects: This invention provides a method for using vat dyes in an overflow dyeing machine. The method involves first alkalizing cationic starch and then reacting it with allyl chloride to introduce double bonds. This is followed by graft copolymerization with acrylic acid and hydroxyacrylate to obtain modified cationic starch. This modified starch exhibits good compatibility with vat dyes and possesses abundant cationic, carboxyl, and hydroxyl groups, enabling uniform dispersion of dye particles and efficient adsorption of vat dyes through electrostatic adsorption. Subsequently, during crosslinking with a crosslinking agent, the agent promotes intermolecular bonding of the modified cationic starch molecules, forming a three-dimensional network structure that encapsulates the adsorbed vat dyes, ultimately yielding a stable and uniformly dispersed dye premix. This preparation process, through chemical bonding rather than simple physical mixing, allows the dye particles to be coated and dispersed within the modified cationic starch, solving the problem of vat dye agglomeration and significantly enhancing the binding force between the dye and the carrier. This lays a structural foundation for uniform dye uptake and stable color fixation during subsequent dyeing processes.

[0018] The use of dye premixes significantly improves dyeing performance in multiple ways. The cationic properties of modified cationic starch allow for electrostatic adsorption with fabric fibers, enabling dye particles coated within it to quickly and evenly adhere to the fabric surface. This avoids uneven dye dispersion in the dye bath, resulting in localized color variations and greatly improving dyeing uniformity. Furthermore, during overflow dyeing, the dye does not aggregate due to water flow impact, ensuring consistent dyeing results across the same batch of fabrics. The stable structure formed by the cross-linking of modified cationic starch and vat dyes creates a protective film on the fabric fiber surface after dyeing and fixing. This film enhances the bonding stability between the dye and fiber, reduces damage to dye molecules from external factors such as light, and improves the dye's lightfastness, increasing the lightfastness of the dyed fabric. The film-forming properties of modified cationic starch also strengthen the bond between the dye and fiber, further preventing fading during fabric use. Ultimately, this achieves a dual improvement in dyeing uniformity and lightfastness, adapting to the dyeing characteristics of overflow dyeing machines and enhancing the overall product quality of vat dye overflow dyeing. Detailed Implementation

[0019] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0020] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0021] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0022] The present invention uses the following raw materials: Cationic starch: degree of substitution 0.1, purchased from Guangdong Hongxin Biotechnology.

[0023] Vat dye: Vinegar blue.

[0024] Degreasing agent: TY336 low-temperature degreasing agent, purchased from Taiyang Chemical.

[0025] Leveling agent: fatty amine polyoxyethylene ether, brand name KRAEA-12, purchased from Guangrao County Kerui Biotechnology Co., Ltd.

[0026] Weak oxidizing agent: Sodium 3-nitrobenzenesulfonate.

[0027] Dispersant: Sodium lignosulfonate, brand name S817764, purchased from Maclean's.

[0028] Strong oxidizing agent: 30 wt% hydrogen peroxide.

[0029] Soap detergent: WD-1207 soap detergent, purchased from Jiangsu World Chemical Co., Ltd.

[0030] All water used in this invention is deionized water.

[0031] In this invention, "parts" refers to parts by mass. Example 1

[0032] A method for dyeing with vat dyes in an overflow dyeing machine includes the following steps: S1. 30 g of cationic starch was dispersed in 100 mL of isopropanol-water mixed solution (mass ratio of isopropanol to water is 8:2) to obtain a starch emulsion; the starch emulsion was heated to 30°C, and 20 mL of sodium hydroxide aqueous solution (2 wt%) was slowly added under stirring, followed by stirring and alkalization for 30 min to obtain an alkalized starch emulsion; 1.5 mL of allyl chloride solution (concentration 30 wt%, solvent isopropanol-water mixed solution with mass ratio of isopropanol to water of 8:2) was slowly added to the alkalized starch emulsion, and the reaction was continued to be stirred for 24 h. The pH was adjusted to neutral with hydrochloric acid (2 wt%), and the mixture was filtered, washed, and dried to obtain cationic starch containing double bonds; S2. Using water as a solvent, the double-bonded cationic starch, acrylic acid, and hydroxyethyl acrylate were blended (the mass ratio of double-bonded cationic starch, acrylic acid, and hydroxyethyl acrylate was 10:1:1), and ammonium persulfate (1 wt% of the total mass of the reactants) was added. The mixture was reacted under nitrogen protection at 70°C for 4 h, filtered, washed, and dried to obtain modified cationic starch. S3. The modified cationic starch, vat dye, glyoxal and water are mixed (the mass ratio of modified cationic starch, vat dye, glyoxal and water is 10:0.5:0.1:100), and the mixture is heated and stirred at 80°C for 5 h to obtain a dye premix. S4. Place the fabric to be dyed in a washing machine and use water containing degreasing agent (adjust the final concentration of degreasing agent in the liquid of the washing machine to 3 g / L) for degreasing and cleaning for 1 hour; place the cleaned fabric to be dyed in an overflow dyeing machine, add water, add the dye premix and leveling agent (calculate the corresponding amount of dye premix based on the amount of vat dye 0.5% OWF; the amount of leveling agent added is 0.5% OWF), the liquor ratio is 1:10, and run the overflow dyeing machine at 80℃ for 15 minutes; then add sodium hydroxide (adjust the final concentration of sodium hydroxide in the liquid of the overflow dyeing machine to 8 g / L) and sodium dithionite (adjust the final concentration of sodium dithionite in the liquid of the overflow dyeing machine to 6 g / L), raise the temperature to 90℃, run the overflow dyeing machine for 40 minutes, then perform overflow washing for 20 minutes, drain the water and add water to obtain the pre-dyed fabric; S5. Add a weak oxidant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 3 g / L) and a dispersant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 2 g / L) to the pre-dyed fabric, heat at 60°C for 10 min; then add a strong oxidant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 3 g / L for hydrogen peroxide), heat at 60°C for 10 min, drain and add water; then add soaping agent to wash, drain, and dry to obtain the dyed fabric. Example 2

[0033] A method for dyeing with vat dyes in an overflow dyeing machine includes the following steps: S1. 40 g of cationic starch was dispersed in 100 mL of isopropanol-water mixed solution (mass ratio of isopropanol to water is 8:2) to obtain a starch emulsion; the starch emulsion was heated to 35°C, and 25 mL of sodium hydroxide aqueous solution (2 wt%) was slowly added under stirring, followed by stirring and alkalization for 30 min to obtain an alkalized starch emulsion; 2 mL of allyl chloride solution (concentration 30 wt%, solvent isopropanol-water mixed solution with mass ratio of isopropanol to water of 8:2) was slowly added to the alkalized starch emulsion, and the reaction was continued to be stirred for 24 h. The pH was adjusted to neutral with hydrochloric acid (2 wt%), filtered, washed, and dried to obtain cationic starch containing double bonds; S2. Using water as a solvent, the double-bonded cationic starch, acrylic acid, and hydroxyethyl acrylate were blended (the mass ratio of double-bonded cationic starch, acrylic acid, and hydroxyethyl acrylate was 10:1:0.8), and ammonium persulfate (1 wt% of the total mass of the reactants) was added. The mixture was reacted under nitrogen protection at 75°C for 4 h, filtered, washed, and dried to obtain modified cationic starch. S3. The modified cationic starch, vat dye, glyoxal and water are mixed (the mass ratio of modified cationic starch, vat dye, glyoxal and water is 10:0.5:0.1:100), and the mixture is heated and stirred at 85°C for 5 h to obtain a dye premix. S4. Place the fabric to be dyed in a washing machine and use water containing degreasing agent (adjust the final concentration of degreasing agent in the liquid of the washing machine to 3 g / L) for degreasing and cleaning for 1 hour; place the cleaned fabric to be dyed in an overflow dyeing machine, add water, add the dye premix and leveling agent (calculate the corresponding amount of dye premix based on the amount of vat dye 0.5% OWF; the amount of leveling agent added is 0.5% OWF), the liquor ratio is 1:10, and run the overflow dyeing machine at 80℃ for 15 minutes; then add sodium hydroxide (adjust the final concentration of sodium hydroxide in the liquid of the overflow dyeing machine to 8 g / L) and sodium dithionite (adjust the final concentration of sodium dithionite in the liquid of the overflow dyeing machine to 6 g / L), raise the temperature to 90℃, run the overflow dyeing machine for 40 minutes, then perform overflow washing for 20 minutes, drain the water and add water to obtain the pre-dyed fabric; S5. Add a weak oxidant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 3 g / L) and a dispersant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 2 g / L) to the pre-dyed fabric, heat at 60°C for 10 min; then add a strong oxidant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 3 g / L for hydrogen peroxide), heat at 60°C for 10 min, drain and add water; then add soaping agent to wash, drain, and dry to obtain the dyed fabric. Example 3

[0034] A method for dyeing with vat dyes in an overflow dyeing machine includes the following steps: S1. 30 g of cationic starch was dispersed in 100 mL of isopropanol-water mixed solution (mass ratio of isopropanol to water is 8:2) to obtain a starch emulsion; the starch emulsion was heated to 40 °C, and 20 mL of sodium hydroxide aqueous solution (2 wt%) was slowly added under stirring, followed by stirring and alkalization for 30 min to obtain an alkalized starch emulsion; 2 mL of allyl chloride solution (concentration 30 wt%, solvent isopropanol-water mixed solution with mass ratio of isopropanol to water of 8:2) was slowly added to the alkalized starch emulsion, and the reaction was continued to be stirred for 24 h. The pH was adjusted to neutral with hydrochloric acid (2 wt%), and the mixture was filtered, washed, and dried to obtain cationic starch containing double bonds. S2. Using water as a solvent, the double-bonded cationic starch, acrylic acid, and hydroxyethyl acrylate were blended (the mass ratio of double-bonded cationic starch, acrylic acid, and hydroxyethyl acrylate was 10:0.8:1.2), and ammonium persulfate (1 wt% of the total mass of the reactants) was added. The mixture was reacted under nitrogen protection at 80°C for 4 h, filtered, washed, and dried to obtain modified cationic starch. S3. The modified cationic starch, vat dye, glyoxal and water are mixed (the mass ratio of modified cationic starch, vat dye, glyoxal and water is 10:0.4:0.1:100), and the mixture is heated and stirred at 90°C for 4 h to obtain a dye premix. S4. Place the fabric to be dyed in a washing machine and use water containing degreasing agent (adjust the final concentration of degreasing agent in the liquid of the washing machine to 3 g / L) for degreasing and cleaning for 1 hour; place the cleaned fabric to be dyed in an overflow dyeing machine, add water, add the dye premix and leveling agent (calculate the corresponding amount of dye premix based on the amount of vat dye 0.5% OWF; the amount of leveling agent added is 0.5% OWF), the liquor ratio is 1:10, and run the overflow dyeing machine at 80℃ for 15 minutes; then add sodium hydroxide (adjust the final concentration of sodium hydroxide in the liquid of the overflow dyeing machine to 8 g / L) and sodium dithionite (adjust the final concentration of sodium dithionite in the liquid of the overflow dyeing machine to 6 g / L), raise the temperature to 90℃, run the overflow dyeing machine for 40 minutes, then perform overflow washing for 20 minutes, drain the water and add water to obtain the pre-dyed fabric; S5. Add a weak oxidant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 3 g / L) and a dispersant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 2 g / L) to the pre-dyed fabric, heat at 60°C for 10 min; then add a strong oxidant (adjusted to the liquid overflowing the dyeing machine at this time, with a final concentration of 3 g / L for hydrogen peroxide), heat at 60°C for 10 min, drain and add water; then add soaping agent to wash, drain, and dry to obtain the dyed fabric.

[0035] Comparative Example 1 A method for dyeing with vat dyes in an overflow dyeing machine. The difference between this comparative example and Example 1 is that step S1 is omitted, and step S2 is modified as follows: Cationic starch, acrylic acid, and hydroxyethyl acrylate were mixed evenly in a mass ratio of 10:1:1 to obtain modified cationic starch. The other steps and dosages are the same as in Example 1.

[0036] Comparative Example 2 A method for dyeing with vat dyes in an overflow dyeing machine, the difference between this comparative example and Example 1 is that the glyoxal is replaced by water by mass. The other steps and dosages are the same as in Example 1.

[0037] Test case The properties of the dyed fabrics of Example 1 and Comparative Examples 1-2 were tested.

[0038] Test method: (1) Dyeing uniformity: Using the methods of Example 1 and Comparative Examples 1-2, two identical fabrics to be dyed were added and dyed simultaneously in the same dyeing process to obtain dyed fabric 1 and dyed fabric 2 respectively.

[0039] Testing instrument: X-Rite colorimeter; Testing conditions: Measurements were taken under D65 light source and 10° viewing angle conditions, with a measuring aperture of 30 mm. During measurement, the fabric should be flat, and the measuring surface should be avoided from touching it with hands. Each sample was measured four times, and the average value was taken. The uniformity of dyeing was judged based on the comparison between the color difference and the standard color.

[0040] in, Indicates the total color difference. The smaller the value, the closer the color is to the standard color. The larger the value, the greater the difference from the standard color. (This refers to dyed fabric 1 and dyed fabric 2.) The closer the values ​​are, the better the staining uniformity.

[0041] The test results are shown in Table 1.

[0042] Table 1 Results of staining uniformity test

[0043] (2) Light fastness: The dyed fabrics were prepared using the methods of Example 1 and Comparative Examples 1-2. After the dyed fabrics were exposed to sunlight for 24, 48 and 72 h respectively, the color change of the samples was evaluated using a gray card. The results were divided into 5 grades, with grade 5 being the best and grade 1 being the worst.

[0044] The test results are shown in Table 2.

[0045] Table 2 Results of sunlight fastness test

[0046] The test results above show that, in the dyeing uniformity test, the dyed fabric prepared in Example 1 of this invention exhibits better uniformity than two pieces of fabric dyed in the same batch. The values ​​were all at low levels and similar, demonstrating excellent dyeing uniformity; while Comparative Example 1, which did not prepare cationic starch containing double bonds, and Comparative Example 2, which did not add crosslinking agent, showed that the dyed fabrics had... The values ​​are not only higher, but the values ​​of the two pieces of fabric in the same batch are significantly different, and the dyeing uniformity is greatly reduced. This indicates that the addition of modified cationic starch and crosslinking agent in this invention can effectively improve the color uniformity of vat dye in the overflow dyeing process and avoid color difference problems.

[0047] In the lightfastness test, the dyed fabric of Example 1 maintained a lightfastness of 4.5 after 24 h, 48 h, and 72 h of sunlight exposure, demonstrating excellent and stable lightfastness. The dyed fabric of Comparative Example 1 showed a continuous decrease in lightfastness from 4 to 3 as the exposure time increased, indicating poor lightfastness. Although the initial lightfastness of the dyed fabric of Comparative Example 2 was consistent with that of Example 1, it subsequently showed a significant decrease with prolonged exposure time. This demonstrates that the modified cationic starch obtained by the present invention through double bond modification of cationic starch, grafting with acrylic monomers, and crosslinking with a crosslinking agent, combined with vat dyes, can significantly improve the lightfastness of dyed fabrics, enhance the bonding stability between dyes and fabrics, effectively delay fading under sunlight, and greatly improve the lightfastness of dyed fabrics.

[0048] Overall, the vat dye overflow dyeing method of the present invention, through the preparation of modified cationic starch and the formulation of dye premix, not only improves the dyeing uniformity but also significantly enhances the light fastness of dyed fabrics. It solves the technical problems of color difference and poor light fastness that are prone to occur in traditional vat dye overflow dyeing, improves the product quality of vat dye overflow dyeing, and has good application prospects.

[0049] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0050] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for dyeing with vat dyes in an overflow dyeing machine, characterized in that, Includes the following steps: S1. Disperse cationic starch in isopropanol solution, add sodium hydroxide to alkalize, then add allyl chloride and heat and stir to react, to obtain cationic starch containing double bonds; S2. The double-bonded cationic starch, acrylic acid, and hydroxy acrylate are blended together, an initiator is added, and the mixture is heated under inert gas protection to obtain modified cationic starch. S3. The modified cationic starch, vat dye and crosslinking agent are blended and crosslinked to obtain a dye premix; S4. Remove the oil from the fabric to be dyed, place it in an overflow dyeing machine, add the dye premix and leveling agent and perform overflow dyeing to obtain the pre-dyed fabric. S5. Add dyeing auxiliaries to the pre-dyed fabric, heat it, polish it, and dry it to obtain the dyed fabric.

2. The method for dyeing with vat dye in an overflow dyeing machine according to claim 1, characterized in that, In step S1, the mass ratio of the cationic starch to allyl chloride is 100:(1-3).

3. The method for dyeing with vat dye in an overflow dyeing machine according to claim 1, characterized in that, In step S1, the heating temperature is 30-40℃.

4. The method for dyeing with vat dye in an overflow dyeing machine according to claim 1, characterized in that, In step S2, the mass ratio of the double-bonded cationic starch, acrylic acid, and hydroxy acrylate is 10:(0.1-1):(0.5-1.5).

5. The method for dyeing with vat dye in an overflow dyeing machine according to claim 1, characterized in that, In step S2, the heating temperature is 60-80℃.

6. The method for dyeing with vat dye in an overflow dyeing machine according to claim 1, characterized in that, In step S3, the mass ratio of the modified cationic starch, vat dye and crosslinking agent is 10:(0.1-1):(0.01-0.1).

7. The method for dyeing with vat dye in an overflow dyeing machine according to claim 1, characterized in that, In step S3, the crosslinking agent is selected from one or more of glyoxal and glutaraldehyde.

8. The method for dyeing with vat dye in an overflow dyeing machine according to claim 1, characterized in that, In step S4, the leveling agent is selected from one or more of anionic surfactants or nonionic surfactants.

9. The method for dyeing with vat dye in an overflow dyeing machine according to claim 1, characterized in that, In step S5, the dyeing auxiliary agent is selected from one or more of oxidizing agents, dispersants, chelating agents, and soaping agents.

10. The method for dyeing with vat dye in an overflow dyeing machine according to claim 9, characterized in that, In step S5, the oxidant includes a weak oxidant and a strong oxidant; the weak oxidant includes an organic oxidant; and the strong oxidant includes hydrogen peroxide.

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