A method for uv resistant finishing of webbing based on par micro particles

Abstract

The application discloses a kind of based on PAR microparticle's ribbon uvioresistant finishing method, first preparation azido chitosan and alkynylated cellulose nanocrystal, and Click-CS / CNC complex is obtained by click reaction.The complex is emulsified with PAR resin, and PAR microparticle emulsion is prepared, and then finishing fluid is compounded with blocked isocyanate crosslinking agent and penetrant, and the finishing agent is used for the uvioresistant finishing of nylon ribbon.Through Click-CS / CNC complex, hydrophilic shell and steric hindrance are provided, so that PAR microparticle is uniformly dispersed, the bending stiffness increase rate of ribbon after finishing and the softness are reduced;And using its uvioresistant ability, synergistic PAR intrinsic shielding effect makes that ribbon has excellent uvioresistant performance.At the same time, the covalent bonding between the PAR microparticle after modification and the ribbon is enhanced by the composite and the crosslinking agent, and the washability is significantly improved.

Description

Technical Field

[0001] This invention relates to a method for UV-resistant finishing of webbing based on PAR microparticles, belonging to the field of textile functional finishing technology. Background Technology

[0002] Webbing exposed to strong sunlight for extended periods will be continuously irradiated by ultraviolet rays, causing the fibers to age, become brittle, and discolor, significantly reducing their mechanical properties and service life. Therefore, UV-resistant finishing is key to improving product durability.

[0003] Currently, commonly used UV-resistant finishing technologies in the textile industry are mainly divided into two categories: The first category uses organic UV absorbers, which absorb ultraviolet rays and convert them into heat energy to achieve UV protection. However, these finishing agents have drawbacks such as easy decomposition and yellowing under long-term sun exposure, easy migration and washing away, and poor weather resistance and washability, making it difficult to meet the requirements for long-term UV protection. The second category uses inorganic nanoparticles (such as TiO2 and ZnO), which achieve protection by scattering and absorbing ultraviolet rays. Although their washability is better than that of small organic molecules, they have the problem of photocatalytic degradation of fibers, and when added in large quantities, the weave may develop a white frost-like appearance, affecting the product's appearance.

[0004] Polyaryl esters (PARs) are a type of engineering plastic with aromatic rings and ester bonds in their main chain. They possess intrinsic UV shielding properties, achieving almost complete shielding against ultraviolet rays with wavelengths <350nm. They also exhibit excellent weather resistance, are not prone to yellowing, and pose no risk of heavy metals or nanoparticles, making them highly safe. However, PARs are hydrophobic and do not chemically bond with fibers. When directly applied to UV-resistant finishing of webbing, they suffer from poor dispersibility, weak bonding with fibers, and insufficient washability, limiting their application in the textile UV-resistant field.

[0005] In the prior art, although there are related attempts to use PAR for fiber modification (such as the washable and abrasion-resistant UV-resistant polyarylate fiber disclosed in CN202511883823.8), this technology mainly targets the modification of the fiber itself, the process is complex, it is not suitable for the finishing process of webbing, and it does not solve the problem of the dispersion and fixation of PAR particles on the surface of webbing.

[0006] Therefore, developing a finishing method that can solve the above-mentioned defects, achieve uniform dispersion and firm fixation of PAR microparticles on the surface of the webbing, and also have long-lasting UV resistance, good hand feel and washability has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a UV-resistant finishing method for webbing based on PAR microparticles, which can effectively improve the long-term UV resistance of webbing and has good hand feel and washability.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for UV-resistant finishing of webbing based on PAR microparticles includes the following steps:

[0010] Chitosan was dissolved, activated by adding EDC·HCl and NHS, and then reacted by adding azidoacetic acid. After dialysis and freeze-drying, azido-chitosan was obtained.

[0011] Cellulose nanocrystals were dispersed in a solvent, and 4-pentyneic acid, EDC·HCl and DMAP were added to react. After centrifugation, washing and freeze drying, alkynylated cellulose nanocrystals were obtained.

[0012] After mixing and dissolving azido-chitosan and alkyne-modified cellulose nanocrystals, CuSO4·5H2O and sodium ascorbate were added to react the mixture. After dialysis and concentration, a Click-CS / CNC complex dispersion was obtained.

[0013] PAR resin was dissolved in a solvent to obtain an oil phase; deionized water, Click-CS / CNC composite dispersion, composite emulsifier and defoamer were mixed to obtain an aqueous phase; after phase inversion emulsification and solvent removal, an emulsion was obtained.

[0014] The emulsion is mixed with a crosslinking agent, a penetrant, and water to obtain an anti-UV finishing agent. The nylon webbing is then placed in the anti-UV finishing agent and subjected to padding and baking.

[0015] Preferably, the molecular weight of chitosan is 10,000-30,000; the amount of azidoacetic acid used is 0.2-0.6 times the mass of chitosan.

[0016] Preferably, the amount of 4-pentyneic acid used is 0.3-0.5 times the mass of cellulose nanocrystals.

[0017] Preferably, azido-chitosan and alkyne-modified cellulose nanocrystals are mixed at a mass ratio of 1:(1-1.2) and then dissolved in sodium chloride solution. After co-dissolving, the pH of the system is adjusted to 4-6.

[0018] The amounts of CuSO4·5H2O and sodium ascorbate used were 0.3-0.8% and 1-2% of the mass of azide-treated chitosan, respectively.

[0019] The reaction time is 20-28 hours.

[0020] Preferably, in the oil phase, the mass ratio of PAR resin to solvent is 3:(4-5).

[0021] Preferably, in the aqueous phase, the mass ratio of deionized water, Click-CS / CNC complex dispersion, composite emulsifier and defoamer is (120-150):(8-15):(1-3):1;

[0022] The solid content of the Click-CS / CNC composite dispersion is 15-30%.

[0023] Preferably, the mass ratio of the PAR resin in the oil phase to the Click-CS / CNC composite dispersion in the aqueous phase is (10-20):1.

[0024] Preferably, the composite emulsifier is composed of nonionic emulsifier AEO-9 and anionic emulsifier sodium dodecylbenzenesulfonate in a mass ratio of (1-3):1.

[0025] Preferably, in the UV-resistant finishing agent, the crosslinking agent is a blocked isocyanate crosslinking agent; in the UV-resistant finishing agent, the emulsion content is 15-25%, the crosslinking agent content is 0.1-0.5%, the penetrant content is 0.1-0.3%, and the balance is water.

[0026] Preferably, the immersion rolling process is a two-dip, two-roll process with a liquid yield of 60-80%; the pre-drying temperature is 80-100℃ for 2-5 minutes; and the baking temperature is 150-160℃ for 60-120 seconds.

[0027] The advantages of this invention are:

[0028] Click chemistry is used to covalently link azidolated chitosan and alkyneated cellulose nanocrystals with triazole rings to form a Click-CS / CNC complex. This complex, as a single functional unit, synergistically adsorbs onto the surface of PAR microparticles during emulsification. The cellulose nanocrystals provide an irreversible Pickering stabilizing effect, while the chitosan provides a hydrophilic shell and reactive anchoring sites. This allows for the acquisition of long-term stable PAR microparticle emulsions with low emulsifier dosage, while simultaneously achieving uniform coating of the complex on the microparticle surface.

[0029] The chitosan in the Click-CS / CNC composite contains abundant amino groups, which undergo amidation with the carboxyl groups at the ends of nylon fibers under baking conditions to form covalent bonds. Simultaneously, the added blocked isocyanate crosslinking agent de-blocks at high temperatures, reacting with the amino groups and fibers to form a three-dimensional network structure. This dual chemical anchoring mechanism firmly fixes the PAR microparticles to the fiber surface, significantly improving the wash resistance of the finished webbing.

[0030] The Click-CS / CNC composite forms a flexible hydrophilic shell on the surface of PAR particles, enabling particle dispersion and fixation without the need for external rigid adhesives. This avoids the fabric stiffening problem caused by traditional adhesives, resulting in a soft hand feel and low increase in bending stiffness after finishing.

[0031] PAR microparticles intrinsically shield short-wave ultraviolet radiation, while cellulose nanocrystals in the Click-CS / CNC composite provide ultraviolet scattering, and the triazole ring also has a certain ultraviolet absorption capacity. The synergistic effect of these multiple ultraviolet protection mechanisms gives the finished webbing excellent UV resistance.

[0032] The triazole ring in the Click-CS / CNC complex and the aromatic structure of the PAR microparticles have a π-π stacking effect, which enhances the adsorption strength of the complex on the microparticle surface. At the same time, the rigid rod-like structure of the cellulose nanocrystals provides steric hindrance, which enables the PAR microparticles to be uniformly dispersed in the aqueous phase and effectively avoids the aggregation of hydrophobic microparticles. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the embodiments.

[0034] Example 1

[0035] Preparation of azido-chitosan.

[0036] 2 g of chitosan (molecular weight 15000, degree of deacetylation 92%) was added to 100 mL of LME S buffer (0.1 mol / L, pH=5.0) and stirred at room temperature for 12 h until completely dissolved. 0.5 g of EDC·HCl and 0.3 g of NHS were added to the above solution and stirred at room temperature for 30 min to activate. 0.8 g of azidoacetic acid was added to the reaction system, and stirring was continued at room temperature for 24 h. The reaction solution was transferred to a dialysis bag (molecular weight cutoff 1000) and dialyzed with distilled water for 48 h (changing the water every 6 h). After dialysis, the solution was freeze-dried to obtain azido-chitosan.

[0037] Preparation of acetylated cellulose nanocrystals.

[0038] 2 g of cellulose nanocrystals were added to 100 mL of anhydrous DMSO and ultrasonically dispersed for 20 min at 400 W. Then, the nanocrystals were sequentially replaced with 75%, 50%, and 25% (v / v) DMSO aqueous solutions, centrifuged after each replacement, and finally washed twice with pure DMSO to maintain the cellulose nanocrystals in a swollen state. 0.8 g of 4-pentyneic acid, 0.7 g of EDC·HCl, and 0.2 g of DMAP (4-dimethylaminopyridine) were added to the above system, and the mixture was stirred at room temperature for 36 h under nitrogen protection. The reaction solution was centrifuged at 12000 rpm for 10 min, the supernatant was discarded, the precipitate was redispersed with distilled water, centrifuged again, and washed three times. The mixture was then freeze-dried to obtain alkynylated cellulose nanocrystals.

[0039] Electrostatic shielding-assisted click chemical precomposite.

[0040] 0.5 g of azide-modified chitosan and 0.5 g of alkydinated cellulose nanocrystals were added to 50 mL of 0.4 mol / L NaCl aqueous solution. The pH of the mixture was adjusted to 5.0 with 0.1 mol / L HCl. 0.0025 g of CuSO4·5H2O and 0.005 g of sodium ascorbate were added to the system, and the mixture was stirred at room temperature for 24 h. The reaction solution was transferred to a dialysis bag (molecular weight cutoff 1000) and dialyzed with deionized water for 48 h (water changed every 6 h) to remove the catalyst and NaCl. After dialysis, the liquid in the bag was concentrated under reduced pressure using a rotary evaporator in a 40 °C water bath at -0.08 MPa vacuum. Concentration was stopped when the solid content reached 20%, yielding a Click-CS / CNC complex dispersion.

[0041] Preparation of PAR microparticle emulsion modified with Click-CS / CNC complex.

[0042] 300g of PAR resin (bisphenol A type, number average molecular weight 40,000) was added to 400g of mixed solvent (the mixed solvent was prepared by dichloromethane and tetrahydrofuran at a volume ratio of 8:2), and stirred at 35℃ for 3h until completely dissolved to obtain a transparent oil phase. 275g of deionized water, 20g of Click-CS / CNC composite dispersion, 3g of composite emulsifier (mass ratio: nonionic emulsifier AEO-9: anionic emulsifier sodium dodecylbenzenesulfonate (SDBS) = 2:1), and 2g of silicone defoamer were mixed and stirred evenly at room temperature to obtain an aqueous phase. The aqueous phase was placed in a high-speed shear mill and sheared at 5000rpm, while the oil phase was slowly added dropwise to the aqueous phase at a rate of 12g / min for 75min. After the addition was complete, shearing continued at 5000rpm for 30min to form an O / W type emulsion.

[0043] The emulsion was transferred to a rotary evaporator and subjected to three stages of vacuum distillation: Stage 1: Water bath temperature set to 35℃, vacuum degree -0.04MPa, distillation for 30 min; Stage 2: Water bath temperature increased to 45℃, vacuum degree -0.07MPa, distillation for 60 min; Stage 3: Water bath temperature increased to 50℃, vacuum degree -0.09MPa, distillation for 30 min. After distillation, the emulsion was allowed to cool naturally to below 30℃ to obtain the Click-CS / CNC modified PAR microparticle emulsion.

[0044] Preparation of UV-resistant finishing solution.

[0045] Add 200g of Click-CS / CNC modified PAR microemulsion to a container. Then add 2g of blocked isocyanate crosslinking agent (Bayer DNateAP) and 1g of penetrant JFC, and then dilute to 1000g with deionized water. Stir at 300rpm for 15min to obtain a homogeneous UV-resistant finishing solution.

[0046] UV-resistant finishing process for nylon webbing.

[0047] Nylon webbing (10mm wide, 2mm thick) was completely immersed in a prepared UV-resistant finishing solution using a two-dip, two-paste process, controlling the padding rate at 70% and the padding temperature at room temperature (25-30℃). The padded webbing was then pre-dried in a 90℃ hot air oven for 2.5 minutes. The pre-dried webbing was then transferred to a baking machine and baked at 155℃ for 90 seconds. After baking, the webbing was removed and allowed to cool naturally to room temperature to obtain the finished UV-resistant webbing.

[0048] Performance testing.

[0049] The UPF value of the finished webbing was determined according to GB / T18830, and the initial UPF value was 102. The finished webbing was subjected to 50 standard water washes according to GB / T3921-2013, and the UPF value was 99.

[0050] According to GJB150.7A-2009 Procedure 2 (steady-state test, simulating long-term photochemical effects, total irradiance 1120W / m², 49℃, 300h), ultraviolet aging treatment was performed, and the strength reduction rate of the webbing was measured to be 4.2%. After 50 standard water washes (GB / T3921-2013), the strength reduction rate was measured again according to the above standard, and it was 4.5%.

[0051] The bending stiffness of the treated webbing was measured using a KES-FB2 fabric style tester. Compared with the untreated webbing, the bending stiffness increased by 3.8%.

[0052] Comparative Example 1

[0053] The procedure is essentially the same as in Example 1, except that the chitosan was not azidized. The specific steps are as follows.

[0054] 0.5 g of chitosan and 0.5 g of alkydinated cellulose nanocrystals were added to 50 mL of 0.4 mol / L NaCl aqueous solution. The pH of the mixture was adjusted to 5.0 with 0.1 mol / L HCl. 0.0025 g of CuSO4·5H2O and 0.005 g of sodium ascorbate were added to the system, and the mixture was stirred at room temperature for 24 h. The reaction solution was transferred to a dialysis bag (molecular weight cutoff 1000) and dialyzed with deionized water for 48 h (water changed every 6 h) to remove the catalyst and NaCl. After dialysis, the liquid in the bag was concentrated under reduced pressure using a rotary evaporator in a 40 °C water bath at -0.08 MPa vacuum. Concentration was stopped when the solid content reached 20%, yielding a CS / CNC composite dispersion.

[0055] 300g of PAR resin (bisphenol A type, number average molecular weight 40,000) was added to 400g of mixed solvent (the mixed solvent was prepared by dichloromethane and tetrahydrofuran at a volume ratio of 8:2), and stirred at 35℃ for 3h until completely dissolved to obtain a transparent oil phase. 275g of deionized water, 20g of CS / CNC composite dispersion, 3g of composite emulsifier (mass ratio: nonionic emulsifier AEO-9: anionic emulsifier sodium dodecylbenzenesulfonate (SDBS) = 2:1), and 2g of silicone defoamer were mixed and stirred evenly at room temperature to obtain an aqueous phase. The aqueous phase was placed in a high-speed shear mill and sheared at 5000rpm, while the oil phase was slowly added dropwise to the aqueous phase at a rate of 12g / min for 75min. After the addition was complete, shearing continued at 5000rpm for 30min to form an O / W type emulsion.

[0056] The emulsion was transferred to a rotary evaporator and subjected to three stages of vacuum distillation: Stage 1: Water bath temperature set to 35℃, vacuum degree -0.04MPa, distillation for 30 min; Stage 2: Water bath temperature increased to 45℃, vacuum degree -0.07MPa, distillation for 60 min; Stage 3: Water bath temperature increased to 50℃, vacuum degree -0.09MPa, distillation for 30 min. After distillation, the emulsion was allowed to cool naturally to below 30℃ to obtain a CS / CNC modified PAR microparticle emulsion.

[0057] Add 200g of CS / CNC modified PAR microemulsion to a container. Then add 2g of blocked isocyanate crosslinking agent (Bayer DNateAP) and 1g of penetrant JFC, and then dilute to 1000g with deionized water. Stir at 300rpm for 15min to obtain a homogeneous UV-resistant finishing solution.

[0058] Nylon webbing (10mm wide, 2mm thick) was completely immersed in a prepared UV-resistant finishing solution using a two-dip, two-paste process, controlling the padding rate at 70% and the padding temperature at room temperature (25-30℃). The padded webbing was then pre-dried in a 90℃ hot air oven for 2.5 minutes. The pre-dried webbing was then transferred to a baking machine and baked at 155℃ for 90 seconds. After baking, the webbing was removed and allowed to cool naturally to room temperature to obtain the finished UV-resistant webbing.

[0059] Because chitosan was not azidated, there was no covalent bond between chitosan and alkynylated CNCs in the click precomposite step; they formed a physical blend only through weak interactions such as hydrogen bonding and electrostatic adsorption. During the emulsification process of PAR microparticle emulsion preparation, chitosan and CNCs in this physical blend adsorbed independently and randomly at the oil / water interface, failing to form synergistically stable functional units. The Pickering effect of CNCs was not fully utilized, and the hydrophilic layer and anchoring sites of chitosan were unevenly distributed. Ultimately, the functionalized shell on the surface of the PAR microparticles exhibited a non-uniform coating: CNC aggregation in some areas led to localized rigidity enhancement, while insufficient hydrophilicity in other areas caused microparticle agglomeration. During baking, due to the uneven distribution of chitosan, the amidation reaction efficiency with nylon fibers decreased, and the crosslinking agent network could not be uniformly covered, resulting in a decrease in anchoring strength. Simultaneously, the CS / alkynylated CNC physical mixture formed a non-uniform coating on the surface of the PAR microparticles, with alkynylated CNCs locally agglomerating in some areas. CNC is a rigid nanorod. After aggregation, it forms a local hard region, which hinders the relative slippage between fibers and increases the rate of increase in bending stiffness.

[0060] The UPF value of the finished webbing was determined according to GB / T18830, and the initial UPF value was 88. The finished webbing was subjected to 50 standard water washes according to GB / T3921-2013, and the UPF value was measured to be 76.

[0061] According to GJB150.7A-2009 Procedure 2 (steady-state test, simulating long-term photochemical effects, total irradiance 1120W / m², 49℃, 300h), ultraviolet aging treatment was performed, and the strength reduction rate of the webbing was measured to be 8.2%. After 50 standard water washes (GB / T3921-2013), the strength reduction rate was measured again according to the above standard, and it was 9.5%.

[0062] The bending stiffness of the treated webbing was measured using a KES-FB2 fabric style tester. Compared with the untreated webbing, the bending stiffness increased by 6.5%.

[0063] Comparative Example 2

[0064] The procedure is essentially the same as in Example 1, except that the cellulose nanocrystals were not alkynylated. The specific steps are as follows.

[0065] 2 g of chitosan (molecular weight 15000, degree of deacetylation 92%) was added to 100 mL of LME S buffer (0.1 mol / L, pH=5.0) and stirred at room temperature for 12 h until completely dissolved. 0.5 g of EDC·HCl and 0.3 g of NHS were added to the above solution and stirred at room temperature for 30 min to activate. 0.8 g of azidoacetic acid was added to the reaction system, and stirring was continued at room temperature for 24 h. The reaction solution was transferred to a dialysis bag (molecular weight cutoff 1000) and dialyzed with distilled water for 48 h (changing the water every 6 h). After dialysis, the solution was freeze-dried to obtain azido-chitosan.

[0066] 0.5 g of azide-modified chitosan and 0.5 g of cellulose nanocrystals were added to 50 mL of 0.4 mol / L NaCl aqueous solution. The pH of the mixture was adjusted to 5.0 with 0.1 mol / L HCl. 0.0025 g of CuSO4·5H2O and 0.005 g of sodium ascorbate were added to the system, and the mixture was stirred at room temperature for 24 h. The reaction solution was transferred to a dialysis bag (molecular weight cutoff 1000) and dialyzed with deionized water for 48 h (water changed every 6 h) to remove the catalyst and NaCl. After dialysis, the liquid in the bag was concentrated under reduced pressure using a rotary evaporator in a 40 °C water bath at -0.08 MPa vacuum. Concentration was stopped when the solid content reached 20%, yielding a CS / CNC complex dispersion.

[0067] 300g of PAR resin (bisphenol A type, number average molecular weight 40,000) was added to 400g of mixed solvent (the mixed solvent was prepared by dichloromethane and tetrahydrofuran at a volume ratio of 8:2), and stirred at 35℃ for 3h until completely dissolved to obtain a transparent oil phase. 275g of deionized water, 20g of CS / CNC composite dispersion, 3g of composite emulsifier (mass ratio: nonionic emulsifier AEO-9: anionic emulsifier sodium dodecylbenzenesulfonate (SDBS) = 2:1), and 2g of silicone defoamer were mixed and stirred evenly at room temperature to obtain an aqueous phase. The aqueous phase was placed in a high-speed shear mill and sheared at 5000rpm, while the oil phase was slowly added dropwise to the aqueous phase at a rate of 12g / min for 75min. After the addition was complete, shearing continued at 5000rpm for 30min to form an O / W type emulsion.

[0068] The emulsion was transferred to a rotary evaporator and subjected to three stages of vacuum distillation: Stage 1: Water bath temperature set to 35℃, vacuum degree -0.04MPa, distillation for 30 min; Stage 2: Water bath temperature increased to 45℃, vacuum degree -0.07MPa, distillation for 60 min; Stage 3: Water bath temperature increased to 50℃, vacuum degree -0.09MPa, distillation for 30 min. After distillation, the emulsion was allowed to cool naturally to below 30℃ to obtain a CS / CNC modified PAR microparticle emulsion.

[0069] Add 200g of CS / CNC modified PAR microemulsion to a container. Then add 2g of blocked isocyanate crosslinking agent (Bayer DNateAP) and 1g of penetrant JFC, and then dilute to 1000g with deionized water. Stir at 300rpm for 15min to obtain a homogeneous UV-resistant finishing solution.

[0070] Nylon webbing (10mm wide, 2mm thick) was completely immersed in a prepared UV-resistant finishing solution using a two-dip, two-paste process, controlling the padding rate at 70% and the padding temperature at room temperature (25-30℃). The padded webbing was then pre-dried in a 90℃ hot air oven for 2.5 minutes. The pre-dried webbing was then transferred to a baking machine and baked at 155℃ for 90 seconds. After baking, the webbing was removed and allowed to cool naturally to room temperature to obtain the finished UV-resistant webbing.

[0071] Symmetrical to Comparative Example 1, azidated chitosan and unmodified CNC only formed a physical blend. During emulsification, chitosan preferentially adsorbed at the oil / water interface (due to its surface activity), while CNC, lacking covalent bonds with chitosan, could not effectively bind to the adsorbed chitosan, leaving most CNC residue in the aqueous phase. This resulted in excessive chitosan accumulation on the surface of PAR particles, forming a thick hydrophilic layer, while insufficient CNC coverage prevented the full utilization of the Pickering stabilizing effect, leading to a certain degree of particle aggregation. During baking, although the excessively accumulated chitosan layer provided more amino groups, the crosslinking agent could not penetrate deeply, reducing effective anchoring points; simultaneously, insufficient CNC facilitated particle aggregation. The excessive accumulation of chitosan on the surface of PAR particles formed a thick polymer layer, which, after drying, exhibited high rigidity, increasing fiber bending resistance and the rate of increase in bending stiffness.

[0072] The UPF value of the finished webbing was determined according to GB / T18830, and the initial UPF value was 87. The finished webbing was subjected to 50 standard water washes according to GB / T3921-2013, and the UPF value was measured to be 75.

[0073] According to GJB150.7A-2009 Procedure 2 (steady-state test, simulating long-term photochemical effects, total irradiance 1120W / m², 49℃, 300h), ultraviolet aging treatment was performed, and the strength reduction rate of the webbing was measured to be 8.3%. After 50 standard water washes (GB / T3921-2013), the strength reduction rate was measured again according to the above standard, and it was 9.7%.

[0074] The bending stiffness of the treated webbing was measured using a KES-FB2 fabric style tester. Compared with the untreated webbing, the bending stiffness increased by 7.8%.

[0075] Comparative Example 3

[0076] The process is essentially the same as in Example 1, except that the Click-CS / CNC complex dispersion was not added during the preparation of the PAR microparticle emulsion. The specific steps are as follows.

[0077] 300g of PAR resin (bisphenol A type, number average molecular weight 40,000) was added to 400g of mixed solvent (the mixed solvent was prepared by mixing dichloromethane and tetrahydrofuran at a volume ratio of 8:2), and stirred at 35℃ for 3h until completely dissolved to obtain a transparent oil phase. 295g of deionized water, 3g of composite emulsifier (mass ratio: nonionic emulsifier AEO-9: anionic emulsifier sodium dodecylbenzenesulfonate (SDBS) = 2:1), and 2g of silicone defoamer were mixed and stirred evenly at room temperature to obtain an aqueous phase. The aqueous phase was placed in a high-speed shear mill and sheared at 5000rpm, while the oil phase was slowly added dropwise to the aqueous phase at a rate of 12g / min for 75min. After the addition was complete, shearing continued at 5000rpm for 30min to form an O / W type emulsion.

[0078] The emulsion was transferred to a rotary evaporator and subjected to three stages of vacuum distillation: Stage 1: Water bath temperature set to 35℃, vacuum degree -0.04MPa, distillation for 30 min; Stage 2: Water bath temperature increased to 45℃, vacuum degree -0.07MPa, distillation for 60 min; Stage 3: Water bath temperature increased to 50℃, vacuum degree -0.09MPa, distillation for 30 min. After distillation, the emulsion was allowed to cool naturally to below 30℃ to obtain a PAR microparticle emulsion.

[0079] Add 200g of PAR microparticle emulsion to a container. Then add 2g of blocked isocyanate crosslinking agent (Bayer DNateAP) and 1g of penetrant JFC, and then dilute to 1000g with deionized water. Stir at 300rpm for 15min to obtain a homogeneous UV-resistant finishing solution.

[0080] Nylon webbing (10mm wide, 2mm thick) was completely immersed in a prepared UV-resistant finishing solution using a two-dip, two-paste process, controlling the padding rate at 70% and the padding temperature at room temperature (25-30℃). The padded webbing was then pre-dried in a 90℃ hot air oven for 2.5 minutes. The pre-dried webbing was then transferred to a baking machine and baked at 155℃ for 90 seconds. After baking, the webbing was removed and allowed to cool naturally to room temperature to obtain the finished UV-resistant webbing.

[0081] PAR microparticles lack any hydrophilic shell or reactive anchoring groups on their surface, making it difficult to completely cover the oil / water interface using only composite emulsifiers. PAR microparticles are prone to partial aggregation during shearing and desolventizing, leading to decreased emulsion stability. During baking, there is a lack of chemical anchoring bridges between PAR microparticles and nylon fibers. Although blocked isocyanate crosslinking agents can self-crosslink to form a network, this network relies solely on physical embedding with the inert PAR microparticles, making the microparticles easily detach from the network during washing. Furthermore, the partial aggregation of PAR microparticles due to the lack of a hydrophilic shell results in agglomerated, hard particles distributed on the fiber surface, forming discontinuous hard regions that hinder fiber bending and increase the rate of increase in bending stiffness.

[0082] The UPF value of the finished webbing was determined according to GB / T18830, and the initial UPF value was 72. The finished webbing was subjected to 50 standard water washes according to GB / T3921-2013, and the UPF value was 58.

[0083] According to GJB150.7A-2009 Procedure 2 (steady-state test, simulating long-term photochemical effects, total irradiance 1120W / m², 49℃, 300h), ultraviolet aging treatment was performed, and the strength reduction rate of the webbing was measured to be 10.8%. After 50 standard water washes (GB / T3921-2013), the strength reduction rate was measured again according to the above standard, and it was 12.5%.

[0084] The bending stiffness of the treated webbing was measured using a KES-FB2 fabric style tester. Compared with the untreated webbing, the bending stiffness increased by 9.2%.

Claims

1. A method for UV-resistant finishing of ribbons based on PAR microparticles, characterized in that, Includes the following steps: Chitosan was dissolved, activated by adding EDC·HCl and NHS, and then reacted by adding azidoacetic acid. After dialysis and freeze-drying, azido-chitosan was obtained. Cellulose nanocrystals were dispersed in a solvent, and 4-pentyneic acid, EDC·HCl and DMAP were added to react. After centrifugation, washing and freeze drying, alkynylated cellulose nanocrystals were obtained. After mixing and dissolving azido-chitosan and alkyne-modified cellulose nanocrystals, CuSO4·5H2O and sodium ascorbate were added to react the mixture. After dialysis and concentration, a Click-CS / CNC complex dispersion was obtained. PAR resin was dissolved in a solvent to obtain an oil phase; deionized water, Click-CS / CNC composite dispersion, composite emulsifier and defoamer were mixed to obtain an aqueous phase; after phase inversion emulsification and solvent removal, an emulsion was obtained. The emulsion is mixed with a crosslinking agent, a penetrant, and water to obtain an anti-UV finishing agent. The nylon webbing is then placed in the anti-UV finishing agent and subjected to padding and baking.

2. The method for UV-resistant finishing of webbing according to claim 1, characterized in that, The molecular weight of chitosan is 10,000-30,000; the amount of azidoacetic acid used is 0.2-0.6 times the mass of chitosan.

3. The method for UV-resistant finishing of webbing according to claim 1, characterized in that, The amount of 4-pentyneic acid used is 0.3-0.5 times the mass of cellulose nanocrystals.

4. The method for UV-resistant finishing of webbing according to claim 1, characterized in that, Azide-modified chitosan and alkyne-modified cellulose nanocrystals were mixed at a mass ratio of 1:(1-1.2) and dissolved in sodium chloride solution. After co-dissolution, the pH of the system was adjusted to 4-6. The amounts of CuSO4·5H2O and sodium ascorbate used were 0.3-0.8% and 1-2% of the mass of azide-treated chitosan, respectively. The reaction time is 20-28 hours.

5. The method for UV-resistant finishing of webbing according to claim 1, characterized in that, In the oil phase, the mass ratio of PAR resin to solvent is 3:(4-5).

6. The method for UV-resistant finishing of webbing according to claim 5, characterized in that, In the aqueous phase, the mass ratio of deionized water, Click-CS / CNC complex dispersion, composite emulsifier and defoamer is (120-150):(8-15):(1-3):1; The solid content of the Click-CS / CNC composite dispersion is 15-30%.

7. The method for UV-resistant finishing of webbing according to claim 6, characterized in that, The mass ratio of the PAR resin in the oil phase to the Click-CS / CNC composite dispersion in the aqueous phase is (10-20):

1.

8. The method for UV-resistant finishing of webbing according to claim 6, characterized in that, The composite emulsifier is composed of nonionic emulsifier AEO-9 and anionic emulsifier sodium dodecylbenzenesulfonate in a mass ratio of (1-3):

1.

9. The method for UV-resistant finishing of webbing according to claim 1, characterized in that, In the UV-resistant finishing agent, the crosslinking agent is a blocked isocyanate crosslinking agent; in the UV-resistant finishing agent, the emulsion content is 15-25%, the crosslinking agent content is 0.1-0.5%, the penetrant content is 0.1-0.3%, and the balance is water.

10. The method for UV-resistant finishing of webbing according to claim 1, characterized in that, The immersion and rolling process employs a two-dip, two-roll process with a liquid yield of 60-80%; the pre-drying temperature is 80-100℃ for 2-5 minutes; and the baking temperature is 150-160℃ for 60-120 seconds.