A process for dyeing of fluorine-free yarn

Abstract

This invention relates to the field of yarn dyeing technology, specifically disclosing a dyeing process for fluoride-free yarn, comprising the steps of yarn loosening, scouring, dyeing, washing off excess dye, and setting. This invention's process is adapted to the material characteristics of fluoride-free yarn, with controllable and repeatable steps. The resulting dyed yarn possesses both excellent appearance and functional properties, making it suitable for the production of outdoor products such as rain jackets, ski suits, and mountaineering backpacks, with broad market application prospects.

Description

Technical Field

[0001] This invention relates to the field of dyeing technology, and specifically to a dyeing process for fluorine-free yarn. Background Technology

[0002] Fluorine-free polyester yarn, free of harmful PFAS and possessing excellent water-repellent properties, has become an environmentally friendly alternative to traditional fluorinated yarns, widely used in outdoor products such as rain jackets, ski suits, camping tents, and footwear. However, the water-repellent layer of fluorine-free yarn places stringent requirements on the dyeing process. Traditional dyeing processes, such as strong alkali scouring, high-temperature setting, and alkali reduction washing, can easily damage this water-repellent layer, leading to a significant decrease in the yarn's water-repellent properties. Furthermore, the high crystallinity of the polyester base material in fluorine-free yarn results in low dye uptake and insufficient colorfastness during dyeing. Moreover, it is difficult to simultaneously maintain the yarn's water-repellent durability and stain-resistance after dyeing, becoming a key bottleneck restricting the industrial application of fluorine-free yarn.

[0003] Currently, existing dyeing processes for fluorine-free yarns mostly focus on simple adjustments to process parameters, failing to incorporate functional auxiliaries to synergistically improve dyeing performance and water repellency. Some auxiliaries added in these processes have poor compatibility with the fluorine-free water-repellent layer, not only failing to improve dyeing results but also further reducing the yarn's water repellency. Furthermore, the application of nanomaterials such as graphene and boron nitride in textile dyeing is often simply added without targeted modification, resulting in poor dispersibility and weak synergistic effects with dyes, making it difficult to fully leverage the modifying advantages of nanomaterials. Therefore, developing a dyeing process adapted to the characteristics of fluorine-free yarns, through the compounding of specialized modified functional auxiliaries, to achieve a synergistic improvement in color fastness, water repellency, and stain resistance, has significant practical importance and market value. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the purpose of this invention is to provide a dyeing process for fluorine-free yarn to solve the problems mentioned in the background art.

[0005] The present invention solves the technical problem by adopting the following technical solution: This invention provides a dyeing process for fluorine-free yarn, comprising the following steps: Step 1, Yarn loosening: Loosen the fluorine-free polyester yarn into the bobbin, control the loosening tension to 8~12N, and the winding density to 0.3~0.5g / cm³, to ensure that the yarn bobbin is fluffy and free of yarn compression; Step 2, Scouring and washing: Scouring and washing the loosened yarn with a weak alkaline scouring agent. The concentration of the weak alkaline scouring agent is 1~2g / L, the liquor ratio is 1:15~1:20, the temperature is 55~65℃, and the time is 20~30min. After washing, rinse with clean water until neutral. Step 3, dyeing: In the dyeing process, the scouring and washing yarn is placed in a dyeing machine, and dye, modified graphene agent, and additives are added for dyeing. The liquor ratio is 1:10~1:15, the dyeing temperature is 125~130℃, and the holding time is 25~35min. The dye is one or more of Disperse Red 60, Disperse Blue 56, and Disperse Yellow 119, and the amount of dye used is controlled below 2% OWF. Step 4, washing away excess dye: After dyeing, first rinse the yarn with warm water at 40~50℃ 2~3 times, 10~15 minutes each time, then adjust the pH of the washing solution to 4.5~5.5 with a dilute acetic acid solution with a mass concentration of 0.5~1g / L, rinse at room temperature for 10 minutes to remove excess dye and avoid alkaline reduction washing; Step 5, setting: Place the washed and dyed yarn in a setting machine and set it at a constant temperature of 140℃ for 70~80 minutes. The hot air velocity during the setting process is 1.5~2m / s. The modified graphene agent is nano-titanium dioxide modified graphene, with a mass concentration of 0.5~1.5 g / L in the dyeing solution; the additive is boron nitride mixed with sodium silicate solution, with a mass concentration of 0.3~0.8 g / L in the dyeing solution; the preparation method of the modified graphene agent is as follows: Add graphene powder to deionized water and ultrasonically disperse for 30-40 minutes to obtain a graphene dispersion with a mass concentration of 2-3 g / L. The ultrasonic power is 300-400 W. Add the nano-titanium dioxide powder to the graphene dispersion at a graphene:nano-titanium dioxide mass ratio of 1:(0.8~1.2), and continue ultrasonic dispersion for 20~30 min to obtain a mixture. The mixture was placed in a water bath and stirred at a constant temperature of 60-70℃ for 1-2 hours at a stirring rate of 300-400 r / min. Then, it was spray dried with an inlet air temperature of 180-200℃ and an outlet air temperature of 80-90℃ to obtain nano-titanium dioxide modified graphene powder, i.e., modified graphene agent.

[0006] Nano-titanium dioxide modifies graphene, which on the one hand improves the dispersibility of graphene in dye liquor, preventing graphene agglomeration and resulting in uneven dyeing; on the other hand, the composite structure of nano-titanium dioxide and graphene can form a dense film on the yarn surface, which works synergistically with the fluorine-free water-repellent layer to improve the water-repellent durability and mechanical properties of the yarn. Simultaneously, the electrical and thermal conductivity of graphene improves the dye uptake rate and color fastness. The preparation method of the additive mentioned in step three is as follows: Prepare a sodium silicate aqueous solution with a mass concentration of 5-8%, and adjust the pH of the solution to 7.0-7.5 with dilute hydrochloric acid to obtain a sodium silicate mixed solution; Boron nitride powder was added to sodium silicate solution at a mass-to-volume ratio of 1g:(10~20)mL and ultrasonically dispersed for 25~35min at an ultrasonic power of 250~350W to obtain a boron nitride suspension mixed with sodium silicate solution, which is the additive.

[0007] Sodium silicate solution, as a modifier, can improve the dispersibility of boron nitride in dye liquor and form a hydrophilic-lipophilic balanced film on the yarn surface, thus improving the yarn's easy stain removal. The layered structure of boron nitride can fill the gaps on the yarn surface and synergize with the modified graphene agent to further improve the yarn's color fastness and water repellency. At the same time, the high temperature resistance and corrosion resistance of boron nitride can improve the yarn's durability.

[0008] Preferably, the weak alkaline refining agent in step two is a compound of sodium carbonate and sodium fatty alcohol polyoxyethylene ether sulfate, with a mass ratio of sodium carbonate to sodium fatty alcohol polyoxyethylene ether sulfate of 1:(0.4~0.6).

[0009] Compared with the prior art, the present invention has the following beneficial effects: The dyeing process of this invention is adapted to the characteristics of fluorine-free yarn throughout the entire process. It adopts weak alkali scouring, acid washing for floating color, and long-term setting at a medium-low temperature of 140℃. The process avoids the damage to the fluorine-free water-repellent layer caused by strong alkali reduction washing and improper high-temperature setting, thus ensuring the original fluorine-free and water-repellent core characteristics of the yarn. The test results show that PFAS was not detected and the water repellency level was ≥4.

[0010] This invention combines nano-titanium dioxide-modified graphene agent and boron nitride additive mixed with sodium silicate solution in the dyeing process. The two work synergistically: nano-titanium dioxide-modified graphene improves the dispersibility of graphene, forming a dense film with the yarn, thereby improving water repellency, color fastness, and mechanical properties; sodium silicate-mixed boron nitride improves the dispersibility of boron nitride, forming a hydrophilic-lipophilic balanced film, improving stain resistance, and filling yarn voids. Together with the modified graphene agent, it enhances color fastness and water repellency, solving the problem of functional property degradation after dyeing of fluorine-free yarn.

[0011] This invention clarifies the optimal preparation method and parameters for modified graphene agents and additives, ensuring the dispersibility of auxiliaries in dye liquor and their binding force with yarn, avoiding problems such as uneven dyeing and functional uniformity caused by auxiliaries agglomeration. At the same time, the process steps are controllable and have good repeatability, making it suitable for large-scale industrial production.

[0012] The dyed fluorine-free yarn prepared by this invention has both excellent appearance and color and functional properties. It exhibits excellent water repellency, durability, easy stain removal, and color fastness, making it suitable for the production of outdoor products such as windproof jackets, ski suits, mountaineering bags, and camping tents. It complies with global environmental regulations and market demands and has broad market application prospects. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Example 1 A dyeing process for fluorine-free yarn includes the following steps: Yarn loosening: Loosen the fluorine-free polyester yarn into the bobbin with a tension of 10N and a winding density of 0.4g / cm³; Refining wash: Use a weak alkaline refining agent (mass ratio 1:0.5) composed of sodium carbonate and sodium fatty alcohol polyoxyethylene ether sulfate, with a mass concentration of 1.5 g / L, a bath ratio of 1:18, a temperature of 60℃, a time of 25 min, and rinse with clean water until neutral. Dyeing: liquor ratio 1:12, dyeing temperature 130℃, holding time 30 min; dye: Disperse Blue 56, dosage 1.5% OWF; modified graphene agent concentration 1.0 g / L, prepared as follows: graphene dispersion (2.5 g / L) ultrasonicated for 35 min (350 W), add equal mass of nano titanium dioxide ultrasonicated for 25 min, constant temperature stirring at 65℃ for 1.5 h (350 r / min), spray dried (inlet air 190℃, outlet air 85℃); additive concentration 0.5 g / L, prepared as follows: 7% sodium silicate aqueous solution adjusted to pH 7.2, boron nitride added at 1 g: 15 mL, ultrasonicated for 30 min (300 W). Washing off excess color: Rinse twice with 45℃ warm water for 12 minutes each time, adjust pH to 5.0 with 0.8g / L dilute acetic acid, and rinse at room temperature for 10 minutes. Setting: Set at 140℃ for 75 minutes, with a hot air velocity of 1.8 m / s.

[0015] Example 2 A dyeing process for fluorine-free yarn includes the following steps: Yarn loosening: Loosen the fluorine-free polyester yarn into the bobbin with a tension of 8N and a winding density of 0.3g / cm³; Refining wash: Use a weak alkaline refining agent (mass ratio 1:0.4) composed of sodium carbonate and sodium fatty alcohol polyoxyethylene ether sulfate, with a mass concentration of 1 g / L, a bath ratio of 1:15, a temperature of 55℃, a time of 20 min, and rinse with clean water until neutral. Dyeing: liquor ratio 1:10, dyeing temperature 125℃, holding time 25 min; dye: Disperse Red 60, dosage 1.0% OWF; modified graphene agent concentration 0.5 g / L, prepared as follows: graphene dispersion (2 g / L) ultrasonicated for 30 min (300 W), 0.8 times the mass of nano titanium dioxide ultrasonicated for 20 min, stirred at 60℃ for 1 h (300 r / min), spray dried (inlet air 180℃, outlet air 80℃); additive concentration 0.3 g / L, prepared as follows: 5% sodium silicate aqueous solution adjusted to pH 7.0, boron nitride added at 1 g: 10 mL, ultrasonicated for 25 min (250 W). Washing off excess color: Rinse twice with 40℃ warm water for 10 minutes each time, adjust pH to 4.5 with 0.5g / L dilute acetic acid, and rinse at room temperature for 10 minutes. Setting: Set at 140℃ for 70 minutes, with a hot air velocity of 1.5m / s.

[0016] Example 3 A dyeing process for fluorine-free yarn includes the following steps: Yarn loosening: Loosen the fluorine-free polyester yarn into the bobbin with a tension of 12N and a winding density of 0.5g / cm³; Refining wash: Use a weak alkaline refining agent (mass ratio 1:0.6) composed of sodium carbonate and sodium fatty alcohol polyoxyethylene ether sulfate, with a mass concentration of 2g / L, a bath ratio of 1:20, a temperature of 65℃, a time of 30min, and rinse with clean water until neutral. Dyeing: liquor ratio 1:15, dyeing temperature 130℃, holding time 35 min; dye: Disperse Yellow 119, dosage 2.0% OWF; modified graphene agent concentration 1.5 g / L, prepared as follows: graphene dispersion (3 g / L) ultrasonicated for 40 min (400 W), 1.2 times the mass of nano titanium dioxide added, ultrasonicated for 30 min, stirred at 70℃ for 2 h (400 r / min), spray dried (inlet air 200℃, outlet air 90℃); additive concentration 0.8 g / L, prepared as follows: 8% sodium silicate aqueous solution adjusted to pH 7.5, boron nitride added at 1 g: 20 mL, ultrasonicated for 35 min (350 W). Washing off floating color: Rinse 3 times with 50℃ warm water, 15min each time, adjust pH to 5.5 with 1g / L dilute acetic acid, and rinse at room temperature for 10min. Setting: Set at 140℃ for 80 minutes, with a hot air velocity of 2m / s.

[0017] Comparative Example To verify the importance of the modified graphene agent and additives in this invention, and the impact of their preparation method on yarn performance, the following comparative examples were set up. All comparative examples used the basic process parameters of Example 1, only changing the type of auxiliary agent or the preparation method in the dye.

[0018] Comparative Example 1: No graphene modifier or additives added The dyeing process only involves adding Disperse Blue 56 dye (1.5% OWF), without adding any modified graphene agent or additives. The remaining steps are completely consistent with those in Example 1.

[0019] Comparative Example 2: Only unmodified graphene agent was added, without any additives. In the dyeing process, Disperse Blue 56 dye (1.5% OWF) and unmodified graphene agent (1.0 g / L, graphene powder is directly ultrasonically dispersed in the dye solution) are added. No additives are added, and the remaining steps are completely consistent with those in Example 1.

[0020] Comparative Example 3: Only unblended boron nitride was added, without any graphene modifier. In the dyeing process, Disperse Blue 56 dye (1.5% OWF) and unmixed boron nitride (0.5 g / L, boron nitride powder was directly ultrasonically dispersed in the dye solution) were added. No modified graphene agent was added. The remaining steps were completely consistent with those in Example 1.

[0021] Comparative Example 4: The modified graphene agent was not modified with nano-titanium dioxide, and the additive was not mixed with sodium silicate during preparation. The modified graphene agent was directly ultrasonically dispersed graphene powder (1.0 g / L), and the additive was directly ultrasonically dispersed boron nitride powder (0.5 g / L). The remaining steps were completely consistent with those in Example 1.

[0022] Comparative Example 5: In the preparation of the modified graphene agent, the mass ratio of graphene to nano-titanium dioxide was 1:2, and the pH of the sodium silicate solution in the additive preparation was 9.0. In the modified graphene agent, the ratio of graphene to nano-titanium dioxide is 1:2. The sodium silicate solution in the additive is not pH adjusted (natural pH 9.0). The remaining steps are completely consistent with those in Example 1.

[0023] Comparative Example 6: Only graphene modifier was added, without boron nitride additive. The nano-titanium dioxide modified graphene agent of Example 1 was used, and the dye concentration was 1.0 g / L; no sodium silicate or boron nitride additives were added; the rest of the loosening, scouring, dyeing parameters, washing, and setting processes were completely consistent with those of Example 1.

[0024] Comparative Example 7: Only boron nitride additives blended with sodium silicate were added, without adding graphene modifiers. The sodium silicate solution of Example 1 was used to mix the boron nitride additive, and the dye concentration was 0.5 g / L; no nano-titanium dioxide modified graphene agent was added; all other process steps and parameters were completely consistent with those of Example 1.

[0025] Performance testing The performance of the dyed fluorine-free yarns prepared in Examples 1-3 and Comparative Examples 1-7 was tested, and the test standards and methods are as follows: PFAS content: Detected using ion chromatography (IC) according to EN14582:2016 to determine whether it was undetectable; Water repellency rating: Refer to GB / T4745-2012 and ISO4920:2012, test the water repellency rating of the original sample and after 50 washes; Stain removability: Refer to FZ / T01118-2012 to test the stain removability color difference level of soy sauce stains; Color fastness: Refer to GB / T3920-2008 to test the color fastness to dry rubbing and determine the grade; Breaking strength: Refer to GB / T3923.1-2013 to test the breaking strength of the yarn and characterize its mechanical properties.

[0026] The test results are shown in Table 1: Table 1. Performance test results of the examples and comparative examples: The following conclusions can be drawn from the test results: The dyed fluorine-free yarns prepared in Examples 1-3 of this invention all achieved PFAS non-detection, meeting environmental protection regulations. They also possess excellent water repellency, easy stain removal, color fastness, and mechanical properties. The original water repellency grade is ≥4, and it remains ≥4 after 50 washes, demonstrating excellent water repellency durability. The color difference grade for easy stain removal with soy sauce is 4-5, the dry rubbing color fastness is ≥4, and the breaking strength is ≥3.7cN / tex. Comparative Example 1: Without the addition of modified graphene agent and additives, the water repellency, color fastness, stain resistance and mechanical properties of the yarn all decreased significantly, indicating that modified graphene agent and additives are the core to achieve synergistic improvement of the functional characteristics and dyeing performance of fluorine-free yarn. Comparative Example 2, which only added unmodified graphene agent, and Comparative Example 3, which only added unblended boron nitride, showed improved yarn performance compared to Comparative Example 1, but were far lower than those in the Example. This indicates that the modified graphene agent and the additives need to be used in combination to fully realize their modifying advantages. Comparative Example 4 did not modify graphene with nano-titanium dioxide or harmonize boron nitride with sodium silicate. Graphene and boron nitride exhibited poor dispersibility in the dye bath and weak bonding with the yarn, failing to form an effective composite functional layer, resulting in limited improvement in yarn performance. Comparative Example 4 also showed lower water repellency, water repellency after washing, stain resistance rating, color fastness, and breaking strength compared to Comparative Examples 2 and 3. This is essentially due to the coexistence of two unmodified and un-surface-harmonized inorganic / carbon-based powders, leading to a negative synergistic effect of agglomeration, system instability, and interface damage. The performance degradation exceeded that of adding a single powder alone. Comparative Example 5 altered the preparation parameters of the modified graphene agent and additives (mass ratio of graphene to nano-titanium dioxide, pH of sodium silicate solution), resulting in a decrease in the modification effect. The yarn's stain resistance, color fastness, and water repellency durability were all lower than those of the Example. This indicates that the preparation method parameters of the modified graphene agent and additives in this invention are the optimal parameters, and deviations from these parameters will significantly affect the modification effect of the additives.

[0027] In Comparative Examples 6 and 7, adding the modified graphene agent of this invention alone effectively improved the water repellency, color fastness, and mechanical properties of the yarn. However, it lacked the gap-filling and hydrophilic-lipophilic film-forming effect of boron nitride, resulting in only average stain-resistance, and the water repellency durability decreased after multiple washes. Adding the sodium silicate-blended boron nitride additive of this invention alone significantly improved the stain-resistance of the yarn, but it lacked the thermally conductive dyeing aid and continuous hydrophobic film reinforcement effect of modified graphene, resulting in limited improvement in water repellency durability, color fastness, and mechanical properties. This demonstrates that the modified graphene agent and the sodium silicate-blended boron nitride additive cannot be simply chosen by selection alone. The two have a clear functional complementarity and synergistic effect. Only when the two modified auxiliaries are used in combination can the water repellency durability, stain-resistance, color fastness, and mechanical properties of the fluorine-free yarn be simultaneously considered. This further confirms the necessity and optimization of the auxiliary compound system and preparation process parameters of this invention.

[0028] Comparative Example 2, with only unmodified graphene added, showed a water repellency level of 3-4, a water repellency level of 2-3 after 50 washes, a dry rubbing fastness level of 3-4, and a tensile strength of 3.2 cN / tex. Comparative Example 6, with only nano-titanium dioxide modified graphene added, showed an improved water repellency level of 4, a water repellency level of 3-4 after 50 washes, a dry rubbing fastness level of 4, and a tensile strength of 3.5 cN / tex. It can be seen that the dispersibility of graphene is significantly improved after modification with nano-titanium dioxide, the hydrophobic film is more dense, and the water repellency durability, color fastness, and mechanical properties are effectively improved, proving that graphene modification is a necessary prerequisite for obtaining excellent results.

[0029] Comparative Example 3, with only unblended boron nitride added, showed a water repellency rating of 3-4 initially, improved to 3 after 50 washes, a color difference rating of 3-4 for easy stain removal, and a tensile strength of 3.3 cN / tex. Comparative Example 7, with only sodium silicate added to blend boron nitride, showed a water repellency rating of 3-4 initially, improved to 3 after 50 washes, increased color difference rating to 4 for easy stain removal, and a tensile strength of 3.4 cN / tex. This demonstrates that boron nitride blending with sodium silicate results in a more uniform dispersion, forming a hydrophilic-oleophilic balanced film, significantly improving easy stain removal. This proves that blending with boron nitride is key to improving easy stain removal performance.

[0030] Modified graphene agents and sodium silicate-boron nitride additives complement each other and have a synergistic effect. Only when the two are used together can they simultaneously take into account water repellency, durability, easy stain removal, color fastness, and mechanical properties, and give full play to the advantages of modification.

[0031] 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.

[0032] 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 dyeing process for fluorine-free yarn, characterized in that, Includes the following steps: Step 1, Yarn loosening: Loosen the fluorine-free polyester yarn into the bobbin, control the loosening tension to 8~12N, and the winding density to 0.3~0.5g / cm³, to ensure that the yarn bobbin is fluffy and free of yarn compression; Step 2, Scouring and washing: Scouring and washing the loosened yarn with a weak alkaline scouring agent. The concentration of the weak alkaline scouring agent is 1~2g / L, the liquor ratio is 1:15~1:20, the temperature is 55~65℃, and the time is 20~30min. After washing, rinse with clean water until neutral. Step 3, dyeing: In the dyeing process, the scouring and washing yarn is placed in a dyeing machine, and dye, modified graphene agent, and additives are added for dyeing. The liquor ratio is 1:10~1:15, the dyeing temperature is 125~130℃, and the holding time is 25~35min. The dye is one or more of Disperse Red 60, Disperse Blue 56, and Disperse Yellow 119, and the amount of dye used is controlled below 2% OWF. Step 4, washing away excess dye: After dyeing, first rinse the yarn with warm water at 40~50℃ 2~3 times, 10~15 minutes each time, then adjust the pH of the washing solution to 4.5~5.5 with a dilute acetic acid solution with a mass concentration of 0.5~1g / L, rinse at room temperature for 10 minutes to remove excess dye and avoid alkaline reduction washing; Step 5, setting: Place the washed and dyed yarn in a setting machine and set it at a constant temperature of 140℃ for 70~80 minutes. The hot air velocity during the setting process is 1.5~2m / s. The modified graphene agent is nano-titanium dioxide modified graphene, with a mass concentration of 0.5~1.5 g / L in the staining solution; the additive is boron nitride mixed with sodium silicate solution, with a mass concentration of 0.3~0.8 g / L in the staining solution; the preparation method of the modified graphene agent is as follows: Add graphene powder to deionized water and ultrasonically disperse for 30-40 minutes to obtain a graphene dispersion with a mass concentration of 2-3 g / L. The ultrasonic power is 300-400 W. Add the nano-titanium dioxide powder to the graphene dispersion at a graphene:nano-titanium dioxide mass ratio of 1:(0.8~1.2), and continue ultrasonic dispersion for 20~30 min to obtain a mixture. The mixture was placed in a water bath and stirred at a constant temperature of 60-70℃ for 1-2 hours at a stirring rate of 300-400 r / min. Then, it was spray-dried at an inlet air temperature of 180-200℃ and an outlet air temperature of 80-90℃ to obtain nano-titanium dioxide modified graphene powder, i.e., the modified graphene agent. The preparation method of the additive mentioned in step three is as follows: Prepare a sodium silicate aqueous solution with a mass concentration of 5-8%, and adjust the pH of the solution to 7.0-7.5 with dilute hydrochloric acid to obtain a sodium silicate mixed solution; Boron nitride powder was added to sodium silicate solution at a mass-to-volume ratio of 1g:(10~20)mL and ultrasonically dispersed for 25~35min at an ultrasonic power of 250~350W to obtain a boron nitride suspension mixed with sodium silicate solution, which is the additive.

2. The dyeing process for fluorine-free yarn according to claim 1, characterized in that, The weak alkaline refining agent mentioned in step two is a compound of sodium carbonate and sodium fatty alcohol polyoxyethylene ether sulfate, with a mass ratio of sodium carbonate to sodium fatty alcohol polyoxyethylene ether sulfate of 1:(0.4~0.6).

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