Polyamide fixing agent and its preparation method and application method

Abstract

The present application relates to the field of fixing agent, in particular to a nylon fixing agent, a preparation method and an application method thereof.The fixing agent is completely suitable for cold rolling fixing process (room temperature, one dip and one roll, treatment time 8-12 seconds), can significantly improve the wet treatment fastness (washing fastness and perspiration fastness) of deep-colored nylon fabric (1.5-2 levels higher than that of untreated fabric), maintain the original soft hand feeling of the fabric, and is free of formaldehyde and does not stick to the roller.

Description

Technical Field

[0001] This invention relates to the field of color-fixing agents, specifically to a nylon color-fixing agent and its preparation and application methods. Background Technology

[0002] Nylon (polyamide fiber, such as nylon 6 and nylon 66) is widely used in high-end sportswear, swimwear, underwear, hosiery, carpets, and military and industrial textiles due to its excellent breaking strength, high elastic recovery rate, abrasion resistance, and good hand feel. In nylon dyeing, anionic dyes (especially weakly acidic dyes, 1:2 metal complex dyes, and some reactive dyes) are the most important type of colorant because they can form ionic and hydrogen bonds with the terminal amino groups of nylon. However, because the amino content in nylon molecules is relatively low (usually 0.03–0.09 mol / kg), and the dye-fiber bond is prone to hydrolysis or dissociation under humid and hot conditions, the wet fastness of dyed nylon fabrics, such as wash fastness, perspiration fastness, and seawater fastness, is significantly insufficient, especially in dark and concentrated colors, where floating color and staining problems are prominent, seriously affecting product quality and performance.

[0003] To improve the wet fastness of nylon dyed fabrics, color-fixing agents are commonly used in industrial finishing processes. Based on literature reports and industrial practice, existing nylon color-fixing agents can be mainly classified into the following categories, each with varying degrees of technical limitations.

[0004] 1. Synthetic tanning agent (phenolsulfonic acid-formaldehyde condensate) This type of fixing agent forms salt bonds between the sulfonic acid groups and the anionic groups on the dye molecules, while the phenolic hydroxyl groups form hydrogen bonds with the amide groups on the fibers, forming an insoluble complex film on the fiber surface, thereby sealing the dye. Literature studies indicate that it can improve the wash fastness of nylon fabrics dyed with acid dyes by 1–2 grades. However, it has significant drawbacks: ① The treatment temperature typically needs to be 70–85℃, and the treatment time 20–30 minutes, resulting in high energy consumption and low production efficiency; ② Residual free formaldehyde remains in the condensate, failing to meet environmental regulations (such as Oeko-Tex Standard 100); ③ After film formation, the fabric feels rough and stiff, and dark-colored fabrics often exhibit a red shift or darkening of the color.

[0005] 2. Polycationic fixing agents (such as quaternary ammonium salts, polyamines, and dicyandiamide condensates) These fixing agents electrostatically bind to anionic dyes via cationic groups, forming a cationic film on the fiber surface. Kamel et al. studied the fixing effect of different cationic polymers on acid-dyed nylon, finding that wash fastness could be improved by 0.5–1 grade, and the hand feel was relatively soft. However, high cationic density can easily lead to flocculation and roller sticking problems in the treatment bath, which is not conducive to continuous production. In addition, the improvement in wash fastness is limited, especially for dark-colored fabrics, because the electrostatic binding is easily destroyed by surfactants after repeated washing.

[0006] 3. Polyurethane or acrylate film-forming fixing agents These types of fixing agents can form a transparent, continuous film on the fiber surface, physically blocking dye migration. Gao et al. synthesized a water-based polyurethane fixing agent, which, after treatment at 80°C for 20 minutes, improved the rubbing fastness of nylon fabrics by approximately one grade. Its advantage lies in its adjustable hand feel, but the density of the film directly determines the fixing effect; an incomplete film results in decreased fastness. More importantly, these fixing agents have extremely poor adaptability to cold-rolling fixing processes: at room temperature, the large molecular chain segments have weak mobility, making it difficult to complete rapid spreading and film formation within seconds, leading to uneven fixing.

[0007] 4. Reactive fixing agents (containing epoxy groups, vinyl sulfone groups, etc.) Attempts have been made to anchor fixing agents to fibers or dyes via covalent bonds. Blackburn et al. synthesized epoxy-containing polyamine fixing agents that can react with the amino groups of fibers at high temperatures (>90°C), significantly improving fastness. However, the reaction conditions are harsh, easily leading to fiber damage and discoloration. Currently, their application in actual production is limited, mainly due to high cost and a narrow process window.

[0008] In recent years, under the background of green and low-carbon development, the textile printing and dyeing industry has vigorously promoted the short-process, low-energy-consumption cold rolling color-fixing process. This process can reduce steam consumption by more than 60%, significantly achieving energy saving, consumption reduction, and labor time savings. However, the harsh process conditions pose new challenges to color-fixing agents: Rapid adsorption and penetration are required: Fixing agent molecules must rapidly diffuse from the solution to the fiber surface and be forced into instantaneous cavities within the fiber under high-pressure roller pressure (typically 3–5 kg / cm²) when the padding solution remains for less than 10 seconds. Traditional film-forming or condensation-type fixing agents, due to their wide molecular weight distribution and low diffusion coefficient, are ill-suited for this task.

[0009] To avoid roller sticking and skin formation: The cold rolling fixing process uses an open rolling mill. If the fixing agent dries or forms a film on the roller surface, it will cause roller sticking and fabric breakage. Existing film-forming fixing agents have poor stability under room temperature and high-speed operation conditions and are prone to solid precipitation.

[0010] Maintaining hand feel and color: Dark-colored nylon fabrics are extremely sensitive to the hand feel of color-fixing agents; any surface film will reduce softness and smoothness. Existing technologies struggle to improve hand feel while simultaneously enhancing colorfastness.

[0011] To address the bottlenecks in cold rolling color fixing processes, some research has been conducted both domestically and internationally. For example, Burkinshaw & Kumar reported a low-temperature color fixing method for acid dyes on nylon in *Dyes and Pigments*, but the treatment still requires 45°C and 15 minutes. Wang et al. proposed a modified color fixing agent based on phenolsulfonic acid-formaldehyde condensate in *Textile Research Journal*, reducing the treatment temperature to 60°C, but the time still requires more than 10 minutes. Liu et al. attempted to apply cationic color fixing agents to room temperature padding processes, finding that the color fixing effect was insufficient within 10 seconds, mainly due to poor molecular chain flexibility and weak affinity with fibers. Kim & Lee explored the "micropore blocking" mechanism of polymer color fixing agents in *Journal of Applied Polymer Science*, but the color fixing agents they studied required high-temperature pretreatment to form an effective pore-blocking structure, which is difficult to achieve under cold rolling conditions. Zhang et al. reviewed the research progress of nylon fixing agents and pointed out that "there is currently a lack of a new type of fixing agent that can quickly anchor to the inside of nylon at room temperature within seconds without forming a surface film." Furthermore, regarding the cold pad-batch color-fixing process for nylon, El-Sayed et al. studied the cold pad-batch color-fixing of nylon dyed with reactive dyes, but mainly focused on the dyeing itself rather than the post-treatment of the color-fixing agent. Chen & Zhao proposed a color-fixing agent containing long-chain alkanes, which can improve the hand feel of nylon, but the improvement in wet fastness on dark-colored fabrics at room temperature is less than 1 grade. In summary, there is currently no nylon color-fixing agent that simultaneously achieves rapid anchoring at room temperature, efficient dye suppression, no damage to hand feel, and no formaldehyde. Moreover, existing color-fixing mechanisms are mostly based on film formation or electrostatic attraction, lacking in-depth utilization of the synergistic mechanism of "micropore physical blocking" and "electrostatic repulsion". Summary of the Invention

[0012] This invention addresses the shortcomings of the existing technology by proposing for the first time a three-dimensional nylon fixing agent based on a synergistic mechanism of "micropore blocking-electrostatic repulsion". The specific solution is as follows: A nylon color-fixing agent, the structural formula of which is as follows: Where R is H, -CH3, or Any one of the following; R1 is any one of H, C1 to C3 alkane groups; n = 3 to 5, m = 3 to 5.

[0013] The structural features and mechanism of action of this structure are as follows: 1. Planar packing configuration, facilitating rapid indentation: The molecular structure contains numerous benzene rings. In aqueous solution, these benzene rings interact through π-π packing, resulting in a regular planar packing configuration of the molecular chain. This configuration allows the fixing agent molecules to be rapidly indented into the instantaneous cavities of the nylon fiber during high-pressure padding (3-5 kg / cm²) in a very short time (<10 seconds).

[0014] 2. High-temperature three-dimensional expansion for micropore sealing: The molecular structure is rich in phenolic hydroxyl groups and long-chain alkanes. The phenolic hydroxyl groups can form strong hydrogen bonds with the amide groups of nylon fibers, while the long-chain alkanes have good affinity with the nylon matrix, jointly enhancing the anchoring ability of the fixing agent within the fiber. During the subsequent high-temperature drying (baking) process, as moisture is lost, the molecular configuration of the fixing agent changes from a planar π-π stacked state to a three-dimensionally expanded, barbed long-chain structure. This structure, like a barb, firmly anchors inside the fiber micropores, achieving physical "micropore sealing" of the dye diffusion channels.

[0015] 3. Introduction of sulfonic acid groups to form electrostatic repulsion: The molecular structure also contains sulfonic acid groups (-SO3⁻X⁺). After baking and fixation, these negatively charged sulfonic acid groups generate a strong electrostatic repulsion with the equally negatively charged anionic dyes, further inhibiting the migration and diffusion of dyes from the fiber interior to the surface and the outside.

[0016] A method for preparing a nylon color-fixing agent includes the following steps: dispersing and dissolving phenolic substances, aromatic sulfonic acid compounds, and alkylbenzene sulfonic acid compounds with a composite catalyst in deionized water, heating to 60-110°C, adding formaldehyde dropwise over 0.5-3 hours under normal pressure, continuing the reaction for 4-18 hours, cooling to 50-80°C, adding 10-30% of the total mass of the previously added materials with a strong acid or concentrated acid, adjusting the pH to 2.0-4.0, and then cooling to obtain the final product; The phenolic substance is one of the following formulas I to IV: The aromatic sulfonic acid compound is one of the following formulas V to VII: .

[0017] The composite catalyst is a potassium hydroxide / boric acid composite catalyst, a sodium hydroxide / boric acid composite catalyst, or an ammonium hydroxide / boric acid composite catalyst.

[0018] The mass ratio of alkali to boric acid in the composite catalyst is 100:0.01 to 0.5.

[0019] The amount of the composite catalyst used is 1 to 15% of the total mass of phenolic substances, aromatic sulfonic acid compounds, and alkylbenzene sulfonic acid compounds.

[0020] The mass ratio of formaldehyde to the total mass of phenolic substances, aromatic sulfonic acid compounds, and alkylbenzene sulfonic acid compounds is 0.1 to 1.5:1.

[0021] The molar ratio of the phenolic substances, aromatic sulfonic acid compounds, and alkylbenzene sulfonic acid compounds is 1:0.5-5:0.5-5.

[0022] The strong acid or concentrated acid mentioned is one or a mixture of two of formic acid and glacial acetic acid.

[0023] A method for applying a nylon color-fixing agent includes the following steps: after dyeing, the nylon fabric is immersed in a working solution containing the nylon color-fixing agent at room temperature and then baked to obtain a color-fixed fabric. The concentration of the nylon color-fixing agent in the working solution is 5-50 g / L. One immersion and one padding are used, and the padding rate is 70-80%.

[0024] The baking temperature is 150-160℃ and the time is 2-3 minutes; the padding time is 8-12 seconds.

[0025] This fixing agent has the following advantages: 1. The molecule contains many benzene rings, which present a regular planar stacking configuration in aqueous solution due to π-π stacking, and can be pressed into instantaneous cavities in nylon fibers under high pressure; 2. Rich in phenolic hydroxyl groups and long-chain alkanes, enhancing affinity with fibers and hydrogen bonding ability; 3. During the high-temperature drying process, the molecular configuration changes from planar stacking to a three-dimensional expanded barbed long chain structure, which is firmly anchored inside the fiber micropores to achieve "micropore sealing"; 4. The molecule also contains sulfonic acid groups, which, after baking, generate electrostatic repulsion with anionic dyes, further inhibiting dye diffusion.

[0026] 5. Thanks to the synergistic mechanism of the advantages 1-4 mentioned above, the color-fixing agent of this invention is fully applicable to the cold rolling color-fixing process (room temperature, one dip and one roll, treatment time 8 seconds). While significantly improving the wet treatment fastness of dark nylon fabrics such as wash resistance and perspiration resistance (1.5-2 grades higher than untreated fabrics), it maintains the original soft hand feel of the fabric, and is formaldehyde-free and does not stick to the rollers, providing a brand-new technical solution for the efficient and energy-saving color-fixing of nylon. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the mechanism of action of the color-fixing agent of the present invention (wherein Figure (a) is a schematic diagram of the planar packing configuration in aqueous solution; Figure (b) is a schematic diagram of the instantaneous pores formed by the packing of flat, layered molecular chains of the color-fixing agent being squeezed into the fiber under high pressure; Figure (c) is a schematic diagram of the three-dimensional expansion after high-temperature baking, forming a "barbed" micropore sealing structure). Figure 2This is a flowchart illustrating the preparation process of the color-fixing agent of the present invention; Figure 3 The retention rate of sulfur content in white cloth after washing before and after water washing with different fixing agents. Detailed Implementation

[0028] The following description, in conjunction with specific examples, provides further details.

[0029] Phenolic substances are one of the following formulas I to IV: Aromatic sulfonic acid compounds are one of the following formulas V to VII: Example 1 (Formula I Phenol + Formula V Aromatic Sulfonic Acid) Synthesis steps: Deionized water was added to the reactor, and formula I phenol, formula V phenol sulfonic acid, and dodecylbenzene sulfonic acid were added in a molar ratio of 1:1.5:1.5, and stirred to disperse. 5% (by mass) of a composite catalyst (sodium hydroxide:boric acid = 100:0.1) was added, and the temperature was raised to 85℃. Formaldehyde (formaldehyde to mixed aromatic compounds in a mass ratio of 0.8:1) was added dropwise over 1 hour. After the addition was complete, the reaction was maintained at this temperature for 8 hours. The temperature was lowered to 60℃, and 15% (by mass) of glacial acetic acid was added to adjust the pH to 3.0. The mixture was then cooled and discharged.

[0030] The product structure of Example 1 is as follows: .

[0031] Application test: working solution concentration 30 g / L, room temperature 25℃ immersion and rolling (one dip and one roll), roll residue 75%, immersion and rolling time 12 s, baking at 160℃ for 2.5 min.

[0032] Test results: Wash fastness improved from grade 2-3 to grade 4-5; hand feel grade 4; sulfur content retention rate 72%; color difference ΔE=0.39; no sticking to the rolls after 4 hours of continuous rolling mill operation.

[0033] Example 2 (Formula II phenol + Formula VI aromatic sulfonic acid) Synthesis steps: The raw materials were replaced with phenol of formula II, methylphenol sulfonic acid of formula VI, and octylbenzene sulfonic acid in a molar ratio of 1:1.5:1.5; the composite catalyst was potassium hydroxide:boric acid = 100:0.2, and the addition amount was 5% of the total mass of the monomers; the temperature was raised to 95°C, and formaldehyde of the same proportion was added dropwise over 1 hour, and the reaction was maintained at this temperature for 10 hours; the pH was adjusted to 3.0 with glacial acetic acid, and the product was cooled and discharged. The remaining operations were the same as in Example 1.

[0034] Example 2 Product Structure: .

[0035] Application testing: The application process is the same as in Example 1.

[0036] Test results: Perspiration fastness improved from level 2 to level 4; hand feel level 4; sulfur content retention rate 80%; color difference ΔE=0.37; no sticking to rollers or skinning during continuous production.

[0037] Example 3 (Formula III phenol + Formula VII aromatic sulfonic acid) Synthesis steps: Add phenolic compounds of formula III, aromatic sulfonic acid compounds of formula VII, and dodecylbenzene sulfonic acid in a molar ratio of 1:1:1; add a composite catalyst (sodium hydroxide:boric acid = 100:0.15) at 8% of the total monomer mass; heat to 80℃; add formaldehyde (mass ratio 0.5:1) dropwise over 0.5 h; maintain the temperature for 6 h; cool to 50℃; adjust pH to 2.0 with formic acid; cool and discharge.

[0038] Example 3 Product Structure: .

[0039] Application test: working fluid concentration 20 g / L, room temperature 22℃ immersion and rolling (one immersion and one rolling), roll residue 70%, immersion and rolling time 10 s, baking at 150℃ for 2 min.

[0040] Test results: Wash fastness to soap is grade 4; wet and dry rubbing fastness is grade 4-5; hand feel is grade 4; sulfur content retention rate is 85%; color difference ΔE=0.35.

[0041] Example 4 (Optimal Example: Formula III Phenol + Formula V Aromatic Sulfonic Acid) Synthesis steps: Add formula III phenolic substances, formula V phenol sulfonic acid, and dodecylbenzene sulfonic acid in a molar ratio of 1:3:3; add 12% (by total mass) of a composite catalyst (ammonium hydroxide: boric acid = 100:0.08), heat to 90℃, add formaldehyde (mass ratio 1.2:1) dropwise over 1.5 h, and maintain the reaction temperature for 12 h. Cool to 70℃, adjust the pH to 4.0 with a mixture of formic acid and glacial acetic acid, and discharge after cooling.

[0042] Example 4 Product Structure: .

[0043] Application test: working solution concentration 40 g / L, room temperature 28℃ immersion and rolling (one dip and one roll), roll residue 80%, immersion and rolling time 10 s, baking at 160℃ for 3 min.

[0044] Test results (optimal performance): Wash fastness to soap is grade 4, acid / alkali perspiration fastness is grade 4-5; sulfur content retention rate is 89%; color difference ΔE=0.31; the fabric is soft and non-clumped, and the color does not shift, making it suitable for large-scale continuous production of dark-colored nylon.

[0045] Example 5 (Formula IV Phenol + Formula VII Aromatic Sulfonic Acid) Synthesis steps: Add formula IV phenolic substances, formula VII aromatic sulfonic acid compounds, and octylbenzene sulfonic acid in a molar ratio of 1:2.5:2.5; the composite catalyst is sodium hydroxide:boric acid = 100:0.1, and the amount added is 7% of the total mass of monomers; heat to 105℃, add formaldehyde (mass ratio 1.1:1) dropwise over 2 hours, and maintain the temperature for 16 hours; adjust the pH to 3.2 with glacial acetic acid, and cool before discharging.

[0046] Example 5 Product Structure: .

[0047] Application test: working solution concentration 35 g / L, room temperature 26℃ immersion and rolling (one dip and one roll), immersion and rolling time 8 s, standard baking process.

[0048] Test results: The fastness to soap washing and perspiration is consistently at level 4 or above; the sulfur content retention rate is 78%~82%; the hand feel is level 4; the working solution does not separate or precipitate after long-term standing, and it has strong adaptability to high and low temperature conditions.

[0049] In cold rolling applications, the preferred concentration of the fixing agent working solution is 20–40 g / L. Too low a concentration will result in insufficient fixing effect, while too high a concentration may slightly affect the feel or cause waste.

[0050] Explanation of preferred numerical range: Based on data from five sets of examples, the core process parameters are divided into protection ranges, preferred ranges, and defective ranges: 1. Synthesis reaction temperature Overall protection range: 60~110℃; preferred range: 80~95℃. Below 60℃, the reaction rate is slow and the color fixing effect is poor; above 110℃, by-products are easily generated, which may lead to the risk of roller sticking.

[0051] 2. Mass ratio of formaldehyde to mixed aromatic compounds Overall protection range: 0.1~1.5:1; Optimal range: 0.5~1.2:1. Too low a ratio results in insufficient condensation, while too high a ratio can lead to residual formaldehyde and decreased permeability.

[0052] 3. Monomer molar ratio (phenols: aromatic sulfonic acids: alkylbenzene sulfonic acids) Overall protection range: 1:0.5~5:0.5~5; Preferred range: 1:1~3:1~3. Abnormal proportion of sulfonic acid monomers will weaken the electrostatic repulsion or fiber anchoring effect.

[0053] 4. Composite catalyst ratio The mass ratio of alkali to boric acid ranges from 100:0.01 to 0.5, preferably from 100:0.05 to 0.2; the catalyst addition amount is 1% to 15%, preferably 5% to 12%.

[0054] 5. Concentration of cold rolling solid working fluid Overall protection range: 5–50 g / L; preferred range: 20–40 g / L. Too low a concentration results in insufficient fastness, while too high a concentration can negatively impact the fabric's hand feel.

[0055] 6. System pH value Overall protection range: 2.0–4.0, preferably 2.5–3.5. Strong acids can damage the molecular structure, and higher pH levels reduce storage stability.

[0056] The present invention relates to the retention rate of sulfur content before and after color fixing agent, and the color fastness rating of nylon colored fabrics after color fixing. [Note] 1. Fixing agent A: German Sinan product; Fixing agent B: Bayer product; Fixing agent C: Tona product; 2. S content retention rate test of fabric: Prepare a 3% owf fixing agent working solution, weigh a certain amount of nylon white fabric, fix it at 75℃ for 30 minutes, wash it thoroughly with water and dry it, measure the S element content of the fabric surface, and then wash the fixed white fabric 5 times at 50℃ and measure the S content of the fabric surface again. 3. Wash fastness: GB / T 3921-2008; Water fastness: AATCC 107-2013; Rubbing fastness: GB / T3920-1997; Perspiration fastness: GB / T-3922-2013; Color difference: tested with Color Eye 7000A.

[0057] 4. Touch: The tactile rating is based on the combined tactile feedback from 5 people with tactile experience (the rating ranges from 1 to 5, where 5 represents the best and 1 represents the worst).

[0058] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

[0059] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A nylon color-fixing agent, characterized in that, Its structural formula is as follows: Where R is H, -CH3, or Any one of the following; R1 is any one of H, C1 to C3 alkane groups; n = 3 to 5, m = 3 to 5.

2. A method for preparing the nylon fixing agent as described in claim 1, characterized in that, The process includes the following steps: dispersing and dissolving phenolic substances, aromatic sulfonic acid compounds, and alkylbenzene sulfonic acid compounds with a composite catalyst in deionized water, heating to 60–110°C, adding formaldehyde dropwise over 0.5–3 hours under normal pressure, continuing the reaction for 4–18 hours, cooling to 50–80°C, adding 10–30% of the total mass of the previously added materials with a strong acid or concentrated acid, adjusting the pH to 2.0–4.0, and then cooling to obtain the final product. The phenolic substance is one of the following formulas I to IV: The aromatic sulfonic acid compound is one of the following formulas V to VII: 。 3. The method for preparing a nylon fixing agent as described in claim 2, characterized in that: The composite catalyst is a potassium hydroxide / boric acid composite catalyst, a sodium hydroxide / boric acid composite catalyst, or an ammonium hydroxide / boric acid composite catalyst.

4. The method for preparing a nylon fixing agent as described in claim 3, characterized in that: The mass ratio of alkali to boric acid in the composite catalyst is 100:0.01 to 0.

5.

5. A method for preparing a nylon fixing agent as described in any one of claims 2-4, characterized in that: The amount of the composite catalyst used is 1 to 15% of the total mass of phenolic substances, aromatic sulfonic acid compounds, and alkylbenzene sulfonic acid compounds.

6. The method for preparing a nylon fixing agent as described in claim 2, characterized in that: The mass ratio of formaldehyde to the total mass of phenolic substances, aromatic sulfonic acid compounds, and alkylbenzene sulfonic acid compounds is 0.1 to 1.5:

1.

7. The method for preparing a nylon fixing agent as described in claim 2, characterized in that: The molar ratio of the phenolic substances, aromatic sulfonic acid compounds, and alkylbenzene sulfonic acid compounds is 1:0.5-5:0.5-5.

8. The method for preparing a nylon fixing agent as described in claim 2, characterized in that: The strong acid or concentrated acid mentioned is one or a mixture of two of formic acid and glacial acetic acid.

9. A method for applying the nylon fixing agent as described in claim 1, characterized in that, The steps are as follows: The dyed nylon fabric is immersed in a working solution containing nylon fixing agent at room temperature and then baked to obtain the fixed fabric. The concentration of nylon fixing agent in the working solution is 5-50 g / L. One immersion and one padding are used, and the padding rate is 70-80%.

10. The application method of a nylon fixing agent as described in claim 9, characterized in that: The baking temperature is 150-160℃ and the time is 2-3 minutes; the padding time is 8-12 seconds.

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