Cotton-polyester blended fabric one-bath dyeing auxiliary agent and preparation method thereof

Abstract

The invention discloses a cotton-polyester blended fabric one-bath dyeing auxiliary agent and a preparation method thereof. The auxiliary agent is prepared by carrying out partial hydrophobization and quaternization on the tail end primary amine group of 2.0-generation polyamide-amine dendrimer and hyperbranched polyethyleneimine with specific molecular weight and branching degree, wherein the molar ratio of the hydrophobization tail end to the quaternary ammonium salt tail end is 1: 9 to 1: 1. The preparation method comprises the following steps: carrying out a controllable amidation reaction under the protection of an inert gas to introduce a C12-C18 alkyl hydrophobic chain, then carrying out a complete quaternization reaction to introduce a trimethyl quaternary ammonium iodate group, and finally carrying out dialysis purification and impurity residue detection to obtain the product. A hydrophobic terminal and a quaternary ammonium salt terminal are simultaneously constructed on a multi-branched polymer skeleton, and the auxiliary agent realizes the synergistic effect of dispersion isolation of a disperse dye and efficient dyeing acceleration and hydrolysis inhibition of a reactive dye, so that the dye uptake and the color fastness are improved in polyester cotton bath dyeing, and the dosage of inorganic salt is reduced.

Description

Technical Field

[0001] This invention relates to the field of textile printing and dyeing technology, specifically to a one-bath dyeing auxiliary agent for polyester-cotton blended fabrics and its preparation method. Background Technology

[0002] Polyester-cotton blended fabrics hold a significant market share in the apparel and home textile industries due to their combination of the high strength, wrinkle resistance, and shape retention of polyester fibers with the moisture absorption, breathability, softness, and comfort of cotton fibers. However, the significant differences in the physicochemical properties of polyester and cotton have made their dyeing process a long-standing technical challenge in the textile printing and dyeing industry.

[0003] Traditional dyeing of polyester-cotton blended fabrics mainly employs a two-bath, two-step method. First, disperse dyes are used to dye the polyester component under neutral to weakly acidic, high-temperature conditions. After reduction washing, reactive dyes are then used to dye the cotton component under alkaline, medium-temperature conditions. While this process ensures that both types of dyes are fixed under optimal conditions, resulting in high color fastness, it suffers from significant drawbacks, including a lengthy process, high energy consumption (water, electricity, steam), high equipment occupancy, and large volumes of complex wastewater. These issues are seriously inconsistent with the current trend towards green, low-carbon, and efficient textile manufacturing.

[0004] To simplify processes and reduce costs, the industry has developed a one-bath dyeing process, aiming to dye polyester and cotton fibers simultaneously in a single dye bath. Based on the dyeing stages, the one-bath method can be further divided into a two-step method and a one-step method. Among these, the one-bath one-step method has become a research hotspot due to its shortest process and highest efficiency potential. However, its implementation faces fundamental challenges arising from the inherent contradictions in the dyeing mechanisms of polyester and cotton fibers. The dyeing temperature and pH conditions conflict: Disperse dyes on polyester require high temperature, high pressure, and a weakly acidic environment to achieve fiber swelling and dye diffusion; while the fixation reaction of reactive dyes on cotton fibers requires a relatively low temperature and a strongly alkaline environment to promote the reaction between the dye and the fiber hydroxyl groups and inhibit dye hydrolysis. It is difficult to reconcile these two drastically different process requirements in a single bath.

[0005] Interference between dyes: Under high temperature and weak acid conditions, reactive dyes are prone to hydrolysis and deactivation, resulting in a sharp drop in dyeing rate and fixation rate; at the same time, nonionic disperse dyes are prone to aggregation in the dye bath and stain the surface of cotton fibers, causing staining of cotton components, dulling of color and decrease in wet fastness, which seriously affects the dyeing quality.

[0006] High salt consumption and environmental pollution: Reactive dyeing typically requires large amounts of inorganic salts as dyeing accelerators to overcome the negative charge repulsion on the surface of cotton fibers. This not only increases production costs but also results in extremely high salinity and chemical oxygen demand in dyeing wastewater, making subsequent treatment difficult and imposing a heavy environmental burden.

[0007] To address these challenges, existing technologies are mainly being improved in two directions: first, developing novel dyes, such as alkali-resistant disperse dyes and high-temperature reactive dyes, to broaden their shared process window; and second, designing specialized dyeing auxiliaries aimed at isolating the two types of dyes, lowering dyeing temperatures, and reducing salt usage. In the latter, microencapsulation technology attempts to prevent disperse dyes from contacting reactive dyes and cotton fibers in the early stages of dyeing by encapsulating them, and then releasing them at high temperatures. However, these methods have significant limitations: the selection range of novel dye systems is narrow, and the costs are high; the preparation process of microcapsules is complex, batch stability is difficult to control, capsule wall materials may introduce new environmental problems, and their effectiveness in simultaneously addressing the hydrolysis and dyeing-promoting issues of reactive dyes is limited.

[0008] In recent years, physical field-assisted dyeing technology has also been introduced, which promotes dye dispersion and fiber penetration through cavitation effects, and can reduce dyeing temperature to some extent. However, this technology relies on specialized equipment, consumes a lot of energy, and its mechanism for inhibiting dye hydrolysis is unclear, posing challenges to process scale-up.

[0009] In summary, existing one-bath, one-step dyeing technologies for polyester-cotton blends, whether based on special dyes, microencapsulated auxiliaries, or physical field assistance, have failed to fundamentally and systematically solve the core contradictions of dye interference, hydrolysis, and high salt consumption. Furthermore, they exhibit significant shortcomings in terms of industrial feasibility, cost-effectiveness, and environmental friendliness. Therefore, developing a one-bath dyeing auxiliary agent that achieves multifunctional integration at the molecular design level, possesses strong process adaptability, demonstrates significant environmental benefits, and is easily industrialized is of urgent practical significance for promoting technological progress and industrial upgrading in the dyeing of polyester-cotton blended fabrics. This invention is proposed against this backdrop. Summary of the Invention

[0010] Purpose of the invention The primary objective of this invention is to provide a one-bath dyeing auxiliary for polyester-cotton blended fabrics. This auxiliary forms a bridge-type bifunctional molecular structure by simultaneously constructing a specific ratio of hydrophobic ends and quaternary ammonium salt ends on a multi-branched polymer backbone. This allows for the synergistic achievement of efficient dispersion and isolation of disperse dyes, and efficient promotion and hydrolysis inhibition of reactive dyes in a single dye bath. Ultimately, this solves the technical bottlenecks of dye interference, severe hydrolysis of reactive dyes, and high inorganic salt consumption in one-bath dyeing of polyester-cotton fabrics, achieving excellent dark-colored dyeing results.

[0011] Another objective of this invention is to provide a method for preparing the aforementioned dyeing auxiliary. This method, by selecting specific polymer precursors, employing stepwise and controllable amidation and quaternization reactions, and combining precise nuclear magnetic resonance quantitative monitoring with rigorous purification and detection procedures, ensures that the final product has a well-defined molecular structure, accurate functional group ratios, and stable and reliable batch performance, thus guaranteeing the reproducible preparation and industrial production feasibility of this high-performance auxiliary.

[0012] Technical solution To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a one-bath dyeing auxiliary for polyester-cotton blended fabrics, wherein the auxiliary is prepared by end-chemical modification of a polymer backbone having at least 8 terminal primary amine groups, wherein the polymer backbone is selected from 2.0 generation polyamide-amine type dendritic polymer and hyperbranched polyethyleneimine; wherein, some of the terminal primary amine groups of the polymer are grafted with C12-C18 alkyl groups through an amidation reaction to form hydrophobic ends; the remaining terminal primary amine groups are converted into trimethyl quaternary ammonium iodide salt by reacting with methyl iodine to form quaternary ammonium salt ends; and the molar ratio of the hydrophobic ends to the quaternary ammonium salt ends is 1:9 to 1:1.

[0013] Furthermore, when the auxiliary agent uses a 2.0 generation polyamide-amine dendritic polymer as its backbone, its hydrophobic terminal structure is -CH2-CH2-NH-CO-R. 1 The terminal structure of the quaternary ammonium salt is -CH2-CH2-N. + (CH3)3 I - , where R 1 It is a C12-C18 alkyl group.

[0014] Furthermore, when the additive uses hyperbranched polyethyleneimine as its backbone, its weight-average molecular weight (Mw) is 5000 to 20000 Daltons, its degree of branching (DB) is 0.4 to 0.8, and its hydrophobic terminal structure is -CH2-CH2-NH-CO-R. 1 The terminal structure of the quaternary ammonium salt is -CH2-CH2-N. + (CH3)3 I - , where R 1 It is a C12-C18 alkyl group.

[0015] Secondly, the present invention provides a method for preparing the above-mentioned dyeing auxiliary agent.

[0016] This method emphasizes process controllability and product reproducibility, and mainly includes the following steps: S1. Raw material preparation: Select one of the following as the precursor: 2.0 generation PAMAM that meets the specifications and PEI of specific Mw and DB.

[0017] S2. Controlled hydrophobicity: Under the protection of an inert gas and in the presence of an acid-binding agent, the precursor reacts with a limited amount of C12-C18 alkyl acyl chloride at a certain temperature. The key is to precisely control the degree of hydrophobicity within the target range by monitoring and calculating the reaction conversion rate using 1H NMR spectroscopy.

[0018] S3. Complete quaternization: Without separating the intermediate, add excess methyl iodine directly to the reaction system of the previous step, and carry out a deep quaternization reaction under heating and reflux conditions until the characteristic peak of the terminal primary amino group is confirmed to have completely disappeared by nuclear magnetic resonance hydrogen spectrum.

[0019] S4. Purification and Quality Control: The reaction solution is dialyzed to remove small molecule impurities, and gas chromatography and ion chromatography are used to detect the residues of key impurities in the product to ensure that their content is below the safety standard. Finally, the product is freeze-dried to obtain a solid product.

[0020] In step S2, an amidation reaction is carried out using C12-C18 alkyl acyl chlorides containing acyl chloride groups, and the degree of hydrophobic modification is precisely controlled between 10% and 50% by nuclear magnetic resonance hydrogen spectroscopy.

[0021] In step S3, an excess of methyl iodine is used to carry out a quaternization reaction to ensure that the remaining primary amine groups are completely converted.

[0022] In step S4, dialysis is used for purification, and key impurities are detected by gas chromatography and ion chromatography.

[0023] This invention forms an auxiliary agent with a bridge-type dual-function structure by simultaneously introducing a specific ratio of hydrophobic ends and quaternary ammonium salt ends onto a single polymer backbone, thereby achieving a synergistic unity of the dispersion and isolation functions for disperse dyes and the efficient dyeing promotion and corrosion inhibition functions for reactive dyes.

[0024] This invention ensures that the resulting adjuvant has a clear molecular structure, uniform distribution of functional groups, and good batch stability by limiting the use of either 2.0 generation PAMAM or PEI with a specific molecular weight and degree of branching as the backbone and employing a precise and controllable two-step chemical modification process.

[0025] The third beneficial effect of this invention is that by using nuclear magnetic resonance hydrogen spectroscopy to quantitatively monitor the degree of hydrophobic modification and setting strict purification and residue detection standards, the controllability and reproducibility of the preparation process are improved, ensuring the purity and safety of the final product.

[0026] By applying the aforementioned auxiliary agent, the quaternary ammonium salt terminal of the agent can neutralize the negative charge on the surface of cotton fibers in the dye bath, significantly reducing or even replacing the amount of inorganic salts used, thus achieving low-salt or even salt-free dyeing and solving the problem of high-salt wastewater pollution in the reactive dyeing process.

[0027] This invention reduces the staining of disperse dyes on cotton fibers during the dyeing process by encapsulating and dispersing disperse dyes through the hydrophobic ends of the auxiliary agent, thereby improving the color fastness and color brightness of the fabric.

[0028] This invention reduces the hydrolysis rate of reactive dyes in the high-temperature alkaline stage by using the auxiliary agent to shield and slow-release reactive dyes in the early stage of dyeing, thereby increasing the fixation rate of reactive dyes and realizing the feasibility of one-bath dark dyeing of polyester-cotton blended fabrics.

[0029] Through the combined effects described above, the dyeing process using this auxiliary agent exhibits advantages such as a short dyeing process, low energy consumption, low chemical consumption, and excellent dyeing depth and fastness, thus solving the key technical problem of unstable dyeing quality in the traditional one-bath method for polyester-cotton dyeing. Attached Figure Description

[0030] Figure 1 This is a flowchart of the preparation method of the one-bath dyeing auxiliary agent for polyester-cotton blended fabrics according to the present invention. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments. Unless otherwise specified, all reagents and raw materials used in the following embodiments are commercially available. The degree of branching (DB) of hyperbranched polyethyleneimine was determined according to the method described in this invention.

[0032] Example 1 This embodiment demonstrates in detail a method for preparing the PAMAM-based adjuvant of the present invention.

[0033] This embodiment uses 2.0 generation polyamide-amine dendritic polymer PAMAM as the backbone, and its hydrophobic ends have the structure shown in formula (A-1): -CH2-CH2-NH-CO-R 1 (A-1), the quaternary ammonium salt has the structure shown in formula (B-1) at its end: -CH2-CH2-N + (CH3)3I - (B-1); where R 1 C 17 H 35 Stearoyl group, detailing a specific preparation method for the dyeing auxiliary of the present invention. This embodiment uses 2.0 generation PAMAM as the polymer backbone, which has eight terminal primary amine groups; through chemical modification, C18 alkyl groups are grafted onto some of its terminals, and the remaining terminals are converted to trimethyl quaternary ammonium iodide, with a molar ratio of the target hydrophobic terminal to the quaternary ammonium salt terminal of approximately 3:7. This embodiment, according to the preparation method of the present invention, includes four steps: S1 providing the precursor, S2 partial terminal hydrophobic modification, S3 complete quaternization modification of the remaining terminals, and S4 purification and detection. Specific materials, proportions, and preparation processes are as follows: Materials and proportions: Precursor polymer: 2.0 generation polyamide-amine dendritic polymer, 1.00 g.

[0034] Hydrophobicating agent: Stearoyl chloride C 17 H35 COCl, 0.28 g.

[0035] Acid-binding agent: triethylamine, 0.14 g.

[0036] Quaternizing reagent: methyl iodine, 1.05 g.

[0037] Solvent: Anhydrous N,N-dimethylformamide, 50 mL.

[0038] Preparation method: S1. Provide the precursor polymer: In a four-necked flask equipped with a stirrer, condenser, nitrogen inlet tube, and thermometer, add PAMAM and 50 mL of anhydrous DMF. Purge the air with dry nitrogen and maintain the atmosphere. Stir until completely dissolved.

[0039] S2. Partial end hydrophobic modification: Triethylamine was added, and the system was cooled to 25°C. Stearoyl chloride was dissolved in 5 mL of anhydrous DMF and slowly added dropwise to the reaction system, controlling the dropping rate to keep the temperature below 30°C. After the addition was complete, the reaction was continuously stirred at 25°C under nitrogen protection for 6 hours. During the reaction, samples were taken at 2, 4, and 6 hours, respectively, and analyzed by... 1 ¹H-NMR monitoring was performed. The proportion of the integrated area of ​​the NH peak of the amide bond to the integrated area of ​​the total primary amine peaks before the reaction was calculated. After 6 hours of reaction, the degree of hydrophobic modification was calculated to be approximately 30%.

[0040] S3. Complete quaternization modification of the remaining terminal phase: Methyl iodine is added directly to the reaction system without separating the intermediate. The temperature is raised to 70°C, and the reaction is carried out under reflux conditions (protected from light and cooled in an ice-water bath) with continuous stirring for 48 hours. Samples are taken every 12 hours during the reaction. 1 H-NMR detection. After 48 hours, the primary amine matrix peak completely disappeared, indicating that the quaternization reaction was complete.

[0041] S4. Purification and Detection: Cool the reaction solution to room temperature, transfer it to a dialysis bag with a molecular weight cutoff of 1000 Da, and dialyze it in continuously stirred flowing deionized water for 60 hours, changing the water every 8 hours.

[0042] The dialysis bag fluid was analyzed by gas chromatography and no methyl iodine residue was detected. Ion chromatography showed that the triethylamine hydrochloride residue was 0.07%.

[0043] The dialysate was freeze-dried to obtain a white flocculent solid product, denoted as auxiliary agent PAMAM-C18-30%. The yield was approximately 85%.

[0044] Example 2 This embodiment uses hyperbranched polyethyleneimine (PEI) as the backbone and employs a shorter-chain alkyl acyl chloride with a hydrophobic end having the structure shown in formula (A-2): -CH2-CH2-NH-CO-R 1 (A-2), the quaternary ammonium salt has the structure shown in formula (B-2) at its end: -CH2-CH2-N + (CH3)3I - (B-2); where R 1 C 13 H 27 Myristoyl groups were used to verify the applicability of the technology to different backbones and hydrophobic chains. Hyperbranched polyethyleneimine (PEI) was selected as the backbone in this example. The target product has a C14 alkyl hydrophobic terminal and a trimethyl quaternary ammonium iodide terminal, with a hydrophobic / quaternary ammonium terminal molar ratio of approximately 1:4. The preparation method is the same as in Example 1. Myristoyl chloride (C...) was used in S2. 13 H 27 COCl). The specific materials, proportions, and preparation process are as follows: Materials and proportions: Precursor polymer: hyperbranched polyethyleneimine (PEI), 1.00 g.

[0045] Hydrophobicating agent: Myristoyl chloride C 13 H 27 COCl, 0.19 g.

[0046] Acid-binding agent: triethylamine, 0.11 g.

[0047] Quaternizing agent: methyl iodine, 1.41 g.

[0048] Solvent: Anhydrous N,N-dimethylformamide, 50 mL.

[0049] Preparation method: The steps are the same as in Example 1, with the following adjustments: In step S2, the temperature is controlled at 25°C during the dropwise addition of myristoyl chloride. After 5 hours of hydrophobication reaction, the degree of modification, calculated by NMR, is approximately 20%.

[0050] The quaternization reaction was carried out at 65°C for 60 hours until the primary amine peak completely disappeared.

[0051] After purification, the residual methyl iodine was <0.08%, and the residual triethylamine hydrochloride was 0.05%. The product was designated as auxiliary agent PEI-C14-20.

[0052] Example 3 This embodiment uses 2.0 generation PAMAM as the backbone, but uses acyl chlorides of different chain lengths to achieve a high degree of hydrophobicity. Its hydrophobic end has the structure shown in formula (A-1): -CH2-CH2-NH-CO-R 1(A-1), the quaternary ammonium salt has the structure shown in formula (B-1) at its end: -CH2-CH2-N + (CH3)3I - (B-1); where R 1 C 15 H 31 Palmitoyl groups were used to explore and verify the effect of the degree of modification on performance. This example uses 2.0 generation PAMAM as the backbone, and the target product has a C16 alkyl hydrophobic terminal and a trimethyl quaternary ammonium iodide terminal, with a hydrophobic / quaternary ammonium terminal molar ratio of approximately 4:6. The preparation method is the same as in Example 1. Palmitoyl chloride C16 is used in S2. 15 H 31 COCl. The specific materials, proportions, and preparation process are as follows: Materials and proportions: Precursor: 2.0 generation PAMAM, 1.00 g.

[0053] Hydrophobicating agent: Palmitoyl chloride C 15 H 31 COCl, 0.38 g.

[0054] Acid-binding agent: triethylamine, 0.21 g.

[0055] Quaternizing reagent: methyl iodine, 0.95 g.

[0056] Solvent: Anhydrous DMF, 50 mL.

[0057] Preparation method: The procedure was the same as in Example 1, with the following adjustments: the amount of palmitoyl chloride was increased, and after 8 hours of hydrophobication reaction, the degree of modification reached approximately 40% according to NMR calculations. Due to the high degree of hydrophobicity, there were few remaining primary amine groups, and the quaternization reaction was completed at 75°C for 36 hours. The purified product was designated as auxiliary agent PAMAM-C16-40%.

[0058] Example 4 This embodiment uses PEI as the framework and verifies the feasibility of the technical solution with a low degree of hydrophobic modification. Its hydrophobic ends have the structure shown in formula (A-2): -CH2-CH2-NH-CO-R 1 (A-2), the quaternary ammonium salt has the structure shown in formula (B-2) at its end: -CH2-CH2-N + (CH3)3I - (B-2); where R 1 C 17 H 35Stearoyl group. The backbone is a hyperbranched PEI that meets the requirements. The target product has a C18 alkyl hydrophobic terminal and a trimethyl quaternary ammonium iodide terminal, with a hydrophobic / quaternary ammonium terminal molar ratio of approximately 1.5:8.5. Stearoyl chloride is used in S2. The specific materials, proportions, and preparation process are as follows: Materials and proportions: Precursor: PEI, 1.00 g.

[0059] Hydrophobicating agent: Stearoyl chloride C 17 H 35 COCl, 0.11 g.

[0060] Acid-binding agent: triethylamine, 0.05 g.

[0061] Quaternizing reagent: methyl iodine, 1.38 g.

[0062] Solvent: Anhydrous DMF, 50 mL.

[0063] Preparation method: The procedure was the same as in Example 1, with the following adjustments: After the addition of stearoyl chloride, the reaction was carried out at 20°C for 10 hours, and the degree of modification was approximately 15% according to NMR calculations. The quaternization reaction was carried out at 70°C for 72 hours to ensure completeness. The purified product was designated as PEI-C18-15%.

[0064] Example 5 This embodiment serves as a comparison with the traditional two-bath, two-step dyeing process, aiming to highlight the comprehensive advantages of using the auxiliaries of this invention for one-bath dyeing through performance comparison.

[0065] Materials and proportions: Fabric: Polyester-cotton blend plain weave fabric, 10g.

[0066] Dyes: Disperse Red 3B, Reactive Red 3BS.

[0067] Additives: Sodium sulfate (Na2SO4) 40 g / L, soda ash (Na2CO3) 20 g / L, commercial dispersant 1 g / L.

[0068] Bath ratio: 1:20.

[0069] Staining method: Prepare the dye bath by adding dye, sodium sulfate, and dispersant, and adjust the pH to 5.5 with acetic acid.

[0070] Insert the fabric and heat it to 60℃ at a rate of 2℃ / min, then keep it at that temperature for 10 minutes.

[0071] Add soda ash and heat to 130°C at a rate of 1°C / min, then hold for 40 minutes.

[0072] Cool down to 80℃ and take a sample.

[0073] The subsequent steps include restoration cleaning, soaping, water washing, and drying.

[0074] This process serves as a benchmark for comparing the effects.

[0075] Test Results and Analysis ; The K / S values ​​and dyeing rates of Examples 1-4 were significantly higher than those of the control group. This directly verifies that the auxiliaries of the present invention can effectively promote the dyeing of reactive dyes and reduce dye hydrolysis, achieving high fixation rate and dark dyeing in a one-bath method.

[0076] The wash fastness and rubbing fastness of Examples 1-4 generally reached grade 4 or above, which is better than grade 3 or below of the control group. This indicates that the hydrophobic end of the auxiliary agent effectively isolates and disperses the disperse dye, reducing its staining on cotton fibers, while the sufficient fixation promoted by the quaternary ammonium salt end also improves the fastness.

[0077] The breaking strength retention rate of Examples 1-4 was higher than that of the control group, indicating that the one-bath process conditions caused less damage to the fibers under the action of the additives.

[0078] Examples 1-4 represent a one-bath process, which significantly shortens the process compared to the two-bath process in Example 5. Furthermore, due to the dyeing-promoting effect of quaternary ammonium salts at the end, the amount of inorganic salts used can be greatly reduced or even replaced, thus reducing the generation of high-salinity wastewater at its source.

[0079] In summary, the dyeing auxiliaries prepared in Examples 1-4 fully verified the technical effects described in this invention in application: through a bifunctional design at the molecular level, the contradictions in the one-bath dyeing process of polyester and cotton were successfully reconciled, achieving a balance of high dye uptake, high color fastness, low fiber damage, and low environmental impact. The control in Example 5, on the other hand, demonstrated the shortcomings of traditional processes, highlighting the technological advancements of this invention.

[0080] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A one-bath dyeing auxiliary agent for polyester-cotton blended fabrics, characterized in that, The additive is prepared by end-chemical modification of a polymer backbone having at least 8 terminal primary amine groups, wherein the polymer backbone is selected from 2.0 generation polyamide-amine dendritic polymer and hyperbranched polyethyleneimine; wherein, some of the terminal primary amine groups of the polymer are grafted with C12-C18 alkyl groups through an amidation reaction to form hydrophobic ends; the remaining terminal primary amine groups are converted into trimethyl quaternary ammonium iodide salt by reacting with methyl iodine to form quaternary ammonium salt ends; and the molar ratio of the hydrophobic ends to the quaternary ammonium salt ends is 1:9 to 1:

1.

2. The dyeing auxiliary agent according to claim 1, characterized in that, The additive uses a 2.0 generation polyamide-amine dendritic polymer as its backbone; the hydrophobic end has the structure shown in formula (A-1): -CH2-CH2-NH-CO-R 1 (A-1), the quaternary ammonium salt has the structure shown in formula (B-1) at its end: -CH2-CH2-N + (CH3)3 I - (B-1); where R 1 It is a C12-C18 alkyl group.

3. The dyeing auxiliary agent according to claim 1, characterized in that, The additive uses hyperbranched polyethyleneimine as its backbone, with a weight-average molecular weight (Mw) of 5000 to 20000 Daltons and a branching degree (DB) of 0.4 to 0.8; the branching degree (DB) is determined by using DMSO-d6 as a solvent. 1 The H-NMR spectrum is calculated using the formula DB = (D+T) / (D+L+T), where D, L, and T represent the relative number of hydrogen atoms in the branched unit, linear unit, and terminal unit, respectively; the hydrophobic terminal has the structure shown in formula (A-2): -CH2-CH2-NH-CO-R 1 (A-2), the quaternary ammonium salt terminal has the structure shown in formula (B-2): -CH2-CH2-N + (CH3)3I - (B-2); where R 1 It is a C12-C18 alkyl group.

4. A method for preparing a dyeing auxiliary agent as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Provide a precursor polymer: a 2.0 generation polyamide-amine dendritic polymer, or a hyperbranched polyethyleneimine with a weight-average molecular weight (Mw) of 5,000 to 20,000 Daltons and a branching degree (DB) of 0.4 to 0.

8. S2. Partial end-hydrophobic modification: The precursor polymer is dissolved in anhydrous N,N-dimethylformamide, triethylamine is added as an acid-binding agent, and then a C12-C18 alkyl acyl chloride containing an acyl chloride group is added. The molar ratio of the acyl chloride compound to the terminal primary amine group of the precursor polymer is controlled to be 0.1:1 to 0.5:

1. The reaction is carried out at 20-40°C under continuous dry nitrogen protection for 4-8 hours with stirring to obtain an intermediate. The reaction progress is monitored by sampling. 1 H-NMR spectroscopy monitoring was used to calculate and control the degree of hydrophobic modification between 10% and 50% by using the ratio of the integrated area of ​​the NH proton peak that forms amide bonds after the reaction to the integrated area of ​​the total terminal primary amine matrix proton peaks measured before the reaction. S3. Complete quaternization modification of the remaining terminal groups: Excess methyl iodine is added to the intermediate reaction mixture obtained in step S2, controlling the molar ratio of the methyl iodine to the remaining terminal primary amino groups in the intermediate to be 3.0:1 to 5.0:

1. The reaction is carried out under reflux conditions (60-80°C, protected from light, and cooled by an ice-water bath) with continuous stirring for 36-72 hours. The reaction endpoint is determined by sampling. 1 H-NMR spectroscopy indicates that the reaction is complete when the terminal primary amine matrix peak completely disappears, yielding the crude reaction product. S4. Purification and Detection: Cool the crude reaction product to room temperature and transfer it to a dialysis bag with a molecular weight cutoff of 1000 Daltons. Dialyze it in continuously stirred flowing deionized water for 48-72 hours. After dialysis, take the dialysate and detect the methyl iodine residue by gas chromatography and the triethylamine hydrochloride residue by ion chromatography, ensuring that the mass fraction of both is less than 0.1%. Then freeze-dry the solution to obtain the dyeing auxiliary agent.

5. The preparation method according to claim 4, characterized in that, In step S2, the C12-C18 alkyl acyl chloride containing an acyl chloride group is selected from myristoyl chloride C 13 H 27 COCl, palmitoyl chloride C 15 H 31 COCl and stearoyl chloride C 17 H 35 One of COCl.

6. The preparation method according to claim 4, characterized in that, In step S2, the degree of hydrophobic modification is 15% to 40%.

7. The preparation method according to claim 4, characterized in that, In step S3, the molar ratio of the methyl iodine to the remaining terminal primary amino group in the intermediate is 4.0:1.

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