Flame-retardant polylactic acid braid and flame-retardant finishing method thereof

Abstract

The invention relates to the technical field of flame-retardant fabrics, in particular to a flame-retardant polylactic acid braid and a flame-retardant finishing method thereof. The flame-retardant finishing method comprises the following steps: sequentially carrying out dipping finishing, padding finishing and coating finishing on the polylactic acid braid, impregnation liquid for impregnation finishing comprises ammonium phytate, organic montmorillonite and isopropanol; coating finishing comprises the steps of mixing water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate to prepare a flame-retardant glue solution, and coating the surface of the polylactic acid braid with the flame-retardant glue solution. According to the flame-retardant finishing method, an ammonium phytate solution is adopted to dip and roll the polylactic acid braid, then ammonium alginate coating finishing is performed, the flame-retardant property of the polylactic acid braid is greatly improved through synergistic flame retardance of the two biomass flame retardants, fire spreading can be effectively prevented under the high-temperature condition, the polylactic acid braid can be rapidly degraded after combustion, and the influence on the environment is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flame-retardant fabrics, and in particular to a flame-retardant polylactic acid webbing and a flame-retardant finishing method thereof. Background Art

[0002] Polylactic acid (PLA) fiber, a biomass material, is biodegradable and biocompatible. In the context of sustainable development and environmental protection, it is increasingly being researched and applied to textile webbing. However, PLA webbing is inherently flammable, with a limiting oxygen index of only around 20%, limiting its application. Therefore, the development of a flame-retardant PLA webbing is crucial.

[0003] Flame-retardant finishing methods for polylactic acid webbing are typically categorized as either additive or reactive. Reactive flame retardants offer long-lasting and stable flame retardancy, with minimal impact on the webbing's physical properties. However, they are complex, costly, and difficult to scale up. Compared to reactive flame retardants, additive flame retardant processes offer advantages such as cost-effectiveness and simplicity, making them more commonly used in production. Currently, additive flame retardants include phosphorus-based and halogen-based flame retardants.

[0004] Chinese invention patent publication number CN109206865A discloses a phosphorus-containing flame-retardant copolymerized polylactic acid (PLA), produced by melt blending star-shaped polylactic acid (PLA), linear polylactic acid (PLA), and a phosphorus-containing flame retardant containing anhydride groups. Phosphorus-based flame retardants decompose under high temperatures to produce highly phosphoric acid-based substances. These substances have a strong dehydrating effect, carbonizing the fabric to form a dense charcoal layer that covers the fabric, insulating it from oxygen and heat. The released water evaporates and absorbs heat to form water vapor, thereby lowering the temperature and diluting the combustible gas, achieving a flame-retardant effect. However, traditional flame retardants, such as phosphorus-based flame retardants, have poor compatibility with PLA webbing. Furthermore, increasing the amount of flame retardant added can also reduce the physical properties of the webbing material itself, adversely affecting its degradability.

[0005] Halogenated flame retardants are inexpensive, require minimal addition, and have good compatibility with materials, allowing flame-retardant products to maintain their original physical and chemical properties. However, they tend to release large amounts of toxic gases and carcinogens when heated, and they generate high amounts of smoke, hindering fire escape and endangering personal safety. Consequently, their use has been gradually restricted in recent years.

[0006] Inorganic flame retardants, mainly aluminum hydroxide and magnesium hydroxide, are stable and low-toxic, suppressing smoke production when textiles burn. However, they are expensive, used in large quantities, and can affect the performance of the ribbon itself.

[0007] Therefore, how to prepare flame-retardant polylactic acid webbing that is low in toxicity, harmless, has good compatibility, does not affect the biodegradable properties of the polylactic acid fiber itself, and has a good flame retardant effect has become a technical issue that needs to be considered. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a flame-retardant polylactic acid webbing and a flame-retardant finishing method thereof which does not affect the biodegradable properties of the polylactic acid fiber itself and can achieve good flame-retardant effect.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: a flame retardant finishing method for a flame retardant polylactic acid webbing, comprising the following steps: sequentially performing dipping finishing, padding finishing and coating finishing on the polylactic acid webbing; The impregnation liquid for the impregnation finishing comprises ammonium phytate, organic montmorillonite and isopropyl alcohol; The coating finishing comprises the steps of mixing water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate to prepare a flame retardant adhesive solution, and coating the surface of the polylactic acid ribbon with the flame retardant adhesive solution.

[0010] The technical solution adopted by the present invention is: a flame-retardant polylactic acid webbing is prepared by the flame-retardant finishing method of the flame-retardant polylactic acid webbing.

[0011] The beneficial effects of the present invention are as follows: the flame retardant finishing method of the flame retardant polylactic acid webbing of the present invention adopts ammonium phytate solution to immerse and roll the polylactic acid webbing, and then performs ammonium alginate coating finishing. The synergistic flame retardancy of the two biomass flame retardants greatly improves the flame retardant performance of the polylactic acid webbing, can effectively prevent the spread of fire under high temperature conditions, and can quickly degrade after burning, reducing the impact on the environment. DETAILED DESCRIPTION

[0012] To explain the technical content, achieved objectives and effects of the present invention in detail, the following describes them in conjunction with the implementation methods.

[0013] A flame retardant finishing method for a flame retardant polylactic acid webbing comprises the following steps: sequentially performing dipping finishing, padding finishing and coating finishing on the polylactic acid webbing; The impregnation solution for impregnation finishing includes ammonium phytate, organic montmorillonite and isopropyl alcohol; The coating finishing comprises the steps of mixing water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate to prepare a flame retardant adhesive solution, and coating the flame retardant adhesive solution on the surface of the polylactic acid ribbon.

[0014] From the above description, it can be seen that the beneficial effects of the present invention are as follows: the existing flame retardants used for the post-finishing of polylactic acid webbing have poor biocompatibility and are difficult to degrade, which has a negative impact on the degradability of the webbing itself, and some flame retardants also cause serious pollution to the environment. The present invention first uses ammonium phytate solution to immerse and roll the polylactic acid webbing. The ammonium phytate is attracted to the fiber molecules by van der Waals force and retained between the fibers, thereby forming a coating with stable structure and performance on the surface of the webbing; then, an ammonium alginate coating is applied for finishing. The two biomass flame retardants are low in toxicity, low in smoke, green and environmentally friendly, and have a synergistic flame retardant effect. It can not only greatly improve the flame retardant properties of the polylactic acid webbing, but also reduce the impact on its physical and mechanical properties, maintaining the excellent degradable properties of polylactic acid.

[0015] The conventional padding and baking method involves padding the polylactic acid webbing in a pre-prepared flame retardant solution, allowing the solution to penetrate the fabric. The fabric then undergoes a pre-baking and baking process to deposit and crosslink the flame retardant. Existing flame-retardant finishing methods only involve a single padding and baking process, resulting in low flame retardant utilization and potentially ineffective flame retardancy. Therefore, further refinement of the flame retardant system is needed. This present invention achieves the secondary objective of cost reduction and efficiency improvement by applying a second coating finish after the padding and dipping process.

[0016] Phytic acid is a strong acid in biomass with a high phosphorus content. Its acidity may destroy the internal structure of the fiber, and polylactic acid fiber is easily hydrolyzed under acidic conditions. In order to reduce the impact of phytic acid acid on polylactic acid webbing, the present invention uses neutral ammonium phytate as a flame retardant. Ammonium phytate decomposes under heat to produce ammonia and phosphoric acid and its derivatives. Phosphoric acid and its derivatives are dehydrated and catalyzed into carbon, isolating air and heat, and ammonia will dilute the content of combustible gas in the gas phase, so that the ammonium phytate flame retardant has both condensed phase flame retardant effects and gas phase flame retardant effects. The cross-linking agent isopropyl alcohol in the impregnation solution is a type of efficient surfactant that is both lipophilic and hydrophilic. It can also be used as a dispersing aid to improve the adhesion of the flame retardant ammonium phytate on the surface of the polylactic acid webbing.

[0017] Ammonium alginate, as a bio-based flame retardant, is not only safe and environmentally friendly, but also highly compatible with polylactic acid (PLA) fibers. Extracted from natural polysaccharides found in brown algae, ammonium alginate exhibits excellent biodegradability. When exposed to high temperatures, the hydroxyl and ammonium groups in the alginate molecular chain break down, resulting in a loose structure and increased internal resistance. This helps slow the spread of heat and combustible materials, inhibiting the spread of fire. Furthermore, during high-temperature combustion, a carbonized layer forms on the alginate surface. This layer isolates the combustible materials from external oxygen, reduces heat transfer, and prevents further internal combustion. Furthermore, when exposed to a fire source, ammonium alginate instantly produces large amounts of water vapor and ammonia through ionic reactions, effectively diluting the surrounding oxygen concentration and lowering the ignition temperature, achieving flame retardancy. Combining ammonium alginate with the similar flame retardant ammonium phytate can enhance flame retardancy while minimizing the flame retardant's negative impact on the degradability of PLA fibers. Adding waterborne polyurethane with relatively good degradation performance to the coating can enhance the interaction between ammonium alginate and polylactic acid to improve the durability of the flame retardant effect.

[0018] Furthermore, the method further includes the steps of sequentially performing pre-treatment and corona treatment before the polylactic acid webbing is subjected to dipping finishing.

[0019] Furthermore, the pre-treatment is specifically as follows: placing the polylactic acid ribbon into a pre-treatment solution and treating it at 75-85°C for 25-35 minutes; The pretreatment solution includes 1.5-2.5 g / L sodium dodecylbenzenesulfonate solution and 0.5-1.5 g / L sodium carbonate.

[0020] Furthermore, the concentration of the sodium dodecylbenzenesulfonate solution is 0.1-0.2 wt %.

[0021] As can be seen from the above description, the ribbon often contains impurities such as slurry, oil, and oil stains that adhere to it during the weaving process. If these impurities are not removed, they will directly affect the subsequent finishing of the PLA ribbon, thereby having a certain negative effect on the biodegradability and flame retardancy of the PLA ribbon. The pretreatment method of the present invention can remove impurities and stains on the surface and interior of the ribbon with minimal damage to the ribbon, ensuring the effective execution of subsequent processes.

[0022] Furthermore, the voltage of the corona treatment is 6~12kV, and the treatment time is 10~20s.

[0023] As can be seen from the above description, corona treatment etches the surface of PLA fibers, roughening them and creating polar groups. This increases the contact area between the fibers and the flame retardant, thereby enhancing the PLA webbing's adhesion to various textile additives. The corona treatment process is energy-efficient and environmentally friendly.

[0024] Furthermore, the impregnation solution includes 6-14 g / L ammonium phytate, 3-5 g / L organic montmorillonite and 15-25 g / L isopropyl alcohol.

[0025] As can be seen from the above description, if too much ammonium phytate is added, its uniformity on the ribbon surface is poor and the flame retardant properties are not significantly improved; if too little is added, the flame retardant effect is reduced. Organic montmorillonite has strong adsorption properties and can impart good flame retardancy to polylactic acid ribbons.

[0026] Adding too much isopropyl alcohol will reduce the elasticity of the ribbon and reduce its recyclability; adding too little will result in poor connection between ammonium phytate and the ribbon.

[0027] Furthermore, the bath ratio of the immersion finishing is 1:10~20.

[0028] Furthermore, the immersion finishing temperature is 60-80°C and the time is 1.5-2.5 hours.

[0029] From the above description, it can be seen that using a relatively low temperature and long time for impregnation can effectively improve the connection strength and uniformity between ammonium phytate and the embryonic strip.

[0030] Furthermore, the padding finishing includes the following steps: rolling the polylactic acid ribbon under the conditions of 1.8~2.2kPa pressure, 8~12r / min rotation speed and 80~100% rolling rate, and baking at 150~170℃ for 2.5~3.5min after drying.

[0031] From the above description, it can be seen that the padding finishing is carried out by impregnating the fabric and applying pressure so that the flame retardant finishing liquid is evenly distributed on the surface or inside of the polylactic acid fiber, thereby giving the webbing excellent flame retardant properties.

[0032] Furthermore, the mass ratio of water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate in the flame retardant adhesive is 86~90:8~12:1:1.

[0033] Preferably, the mass ratio of water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate in the flame retardant adhesive is 90:8:1:1, 88:10:1:1 or 86:12:1:1.

[0034] As can be seen from the above description, the isocyanate in the flame-retardant adhesive forms an isocyanurate ring through a trimerization reaction, which in turn forms a dense carbon layer. This layer blocks heat and oxygen, reduces the release of flammable gases, and enhances flame retardancy. Ethyl acetate has excellent solubility and is biodegradable, making it environmentally friendly.

[0035] When the mass ratio of water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate is 86~90:8~12:1:1, the mass concentration of 8~12%wt is most suitable; if the mass concentration is too low, the flame retardant effect will not meet the expectations; if the mass concentration is too high, the feel of the polylactic acid webbing will become hard and the cost will also increase.

[0036] Furthermore, after the coating is finished, the polylactic acid ribbon is kept at 75-85° C. for 3-5 minutes, then heated to 95-105° C. for 20-30 minutes, and then cooled and allowed to stand at room temperature.

[0037] From the above description, it can be seen that the PLA webbing is first kept at 75~85℃ for 3~5min to remove moisture from the surface of the webbing, ensuring that the flame retardant in the coating can fully penetrate into the PLA fiber, and then the temperature is raised to 95~105℃ and kept for 20~30min for secondary drying, so that the flame retardant reacts chemically with other additives at high temperature to form a stable structure and enhance the flame retardant effect; finally, it is cooled and allowed to stand at room temperature to allow the solvent to fully evaporate and solidify.

[0038] The technical solution adopted by the present invention is: a flame-retardant polylactic acid webbing is prepared by the flame-retardant finishing method of the flame-retardant polylactic acid webbing.

[0039] From the above description, it can be seen that the flame-retardant polylactic acid webbing of the present invention has excellent flame-retardant properties, can effectively prevent the spread of fire under high temperature conditions, and can quickly degrade after burning, reducing the impact on the environment.

[0040] Embodiment 1 of the present invention is a flame retardant finishing method for a flame retardant polylactic acid webbing, comprising the following steps: S1. Pretreatment: Place the polylactic acid ribbon in a pretreatment solution, treat it at 80°C for 30 minutes, and then wash and dry it; the pretreatment solution includes 2g / L sodium dodecylbenzene sulfonate solution with a mass concentration of 0.15wt% and 1g / L sodium carbonate, with a bath ratio of 1:20.

[0041] S2: Corona treatment: The polylactic acid webbing is subjected to corona treatment using a corona discharge apparatus with a treatment voltage of 6 kV and a treatment time of 10 s.

[0042] S3. Impregnation finishing: prepare an impregnation solution with 6g / L ammonium phytate, 3g / L organic montmorillonite and 15g / L isopropyl alcohol, and treat the corona-treated polylactic acid ribbon in a 60°C water bath for 2 hours. The impregnation bath ratio is 1:10.

[0043] S4. Padding finishing: Use a small vertical padder to roll the polylactic acid ribbon at a pressure of 2 kPa, a speed of 10 r / min, and a rolling rate of 80%; after rolling, place the polylactic acid ribbon in a 90°C oven to dry for 3 minutes, and then place it in a shaping dryer at 150°C for baking for 3 minutes.

[0044] S5. Coating finishing: water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate are mixed in a ratio of 90:8:1:1 to prepare an 8wt% flame-retardant adhesive solution. Use a blender to evenly mix the components, and then pour the adhesive solution into the adhesive tank of an automatic coating machine to form a flame-retardant coating on the surface of the polylactic acid webbing.

[0045] S6. Place the polylactic acid ribbon after the flame retardant coating into an oven and pre-bake it at 80°C for 3 minutes, then heat it to 100°C and bake it for 20 minutes. Finally, take it out and cool it at room temperature for 24 hours to allow the solvent to fully evaporate and solidify.

[0046] Embodiment 2 of the present invention is a flame retardant finishing method for a flame retardant polylactic acid webbing, comprising the following steps: S1. Pretreatment: Place the polylactic acid ribbon in a pretreatment solution, treat it at 80°C for 30 minutes, and then wash and dry it; the pretreatment solution includes 2g / L sodium dodecylbenzene sulfonate solution with a mass concentration of 0.15wt% and 1g / L sodium carbonate, with a bath ratio of 1:20.

[0047] S2: Corona treatment: The polylactic acid webbing is subjected to corona treatment using a corona discharge apparatus with a treatment voltage of 9 kV and a treatment time of 15 s.

[0048] S3. Impregnation finishing: prepare an impregnation solution with 10g / L ammonium phytate, 4g / L organic montmorillonite and 20g / L isopropyl alcohol, and treat the corona-treated polylactic acid ribbon in a 70℃ water bath for 2h. The impregnation bath ratio is 1:20.

[0049] S4. Padding finishing: Use a small vertical padder to roll the polylactic acid ribbon at a pressure of 2 kPa, a speed of 10 r / min, and a rolling rate of 90%; after rolling, place the polylactic acid ribbon in a 90°C oven to dry for 3 minutes, and then place it in a shaping dryer and bake at 160°C for 3 minutes.

[0050] S5. Coating finishing: water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate are mixed in a ratio of 88:10:1:1 to prepare a 10wt% flame retardant adhesive solution (the mass concentration is the mass concentration of ammonium alginate). First, use a blender to mix the components evenly, and then pour the adhesive solution into the adhesive tank of the automatic coating machine to form a flame retardant coating on the surface of the polylactic acid webbing.

[0051] S6. Place the polylactic acid ribbon after the flame retardant coating in an oven and pre-bake it at 80°C for 4 minutes, then heat it to 100°C and bake it for 25 minutes. Finally, take it out and cool it at room temperature for 24 hours to allow the solvent to fully evaporate and solidify.

[0052] Embodiment 3 of the present invention is: a flame retardant finishing method for a flame retardant polylactic acid webbing, comprising the following steps: S1. Pretreatment: Place the polylactic acid ribbon in a pretreatment solution, treat it at 80°C for 30 minutes, and then wash and dry it; the pretreatment solution includes 2g / L sodium dodecylbenzene sulfonate solution with a mass concentration of 0.15wt% and 1g / L sodium carbonate, with a bath ratio of 1:20.

[0053] S2: Corona treatment: The polylactic acid webbing is subjected to corona treatment using a corona discharge apparatus with a treatment voltage of 12 kV and a treatment time of 20 s.

[0054] S3. Impregnation finishing: prepare an impregnation solution with 14g / L ammonium phytate, 5g / L organic montmorillonite and 25g / L isopropyl alcohol, and treat the corona-treated polylactic acid ribbon in an 80℃ water bath for 2h. The impregnation bath ratio is 1:20.

[0055] S4. Padding finishing: Use a small vertical padder to roll the polylactic acid ribbon at a pressure of 2 kPa, a speed of 10 r / min, and a rolling rate of 100%; after rolling, place the polylactic acid ribbon in a 90 ° C oven to dry for 3 minutes, and then place it in a shaping dryer at 170 ° C for 3 minutes.

[0056] S5. Coating finishing: water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate are mixed in a ratio of 86:12:1:1 to prepare a 12 wt% flame retardant adhesive solution. Use a blender to mix the components evenly, and then pour the adhesive solution into the adhesive tank of an automatic coating machine to form a flame retardant coating on the surface of the polylactic acid webbing.

[0057] S6. Place the polylactic acid ribbon after the flame retardant coating in an oven and pre-bake it at 80°C for 5 minutes, then heat it to 100°C and bake it for 30 minutes. Finally, take it out and cool it at room temperature for 24 hours to allow the solvent to fully evaporate and solidify.

[0058] Comparative Example 1 of the present invention is a flame retardant finishing method of a conventional flame retardant polylactic acid webbing, comprising the following steps: S1. Pretreatment: Place the polylactic acid ribbon in a pretreatment solution, treat it at 80°C for 30 minutes, and then wash and dry it; the pretreatment solution includes 2g / L sodium dodecylbenzene sulfonate solution with a mass concentration of 0.15wt% and 1g / L sodium carbonate, with a bath ratio of 1:20.

[0059] S3. Impregnation finishing: prepare an impregnation solution with 10g / L ammonium polyphosphate, 4g / L organic montmorillonite and 20g / L isopropyl alcohol, and treat the corona-treated polylactic acid ribbon in a 70℃ water bath for 2h. The impregnation bath ratio is 1:20.

[0060] S4. Padding finishing: Use a small vertical padder to roll the polylactic acid ribbon at a pressure of 2 kPa, a speed of 10 r / min, and a rolling rate of 100%; after rolling, place the polylactic acid ribbon in a 90 ° C oven to dry for 3 minutes, and then place it in a shaping dryer at 160 ° C for 3 minutes.

[0061] Comparative Example 2 of the present invention is a flame retardant finishing method of a conventional flame retardant polylactic acid webbing, comprising the following steps: S1. Pretreatment: Place the polylactic acid ribbon in a pretreatment solution, treat it at 80°C for 30 minutes, and then wash and dry it; the pretreatment solution includes 2g / L sodium dodecylbenzene sulfonate solution with a mass concentration of 0.15wt% and 1g / L sodium carbonate, with a bath ratio of 1:20.

[0062] S3. Impregnation finishing: prepare an impregnation solution with 10g / L aluminum hydroxide, 4g / L organic montmorillonite and 20g / L isopropyl alcohol, and treat the corona-treated polylactic acid ribbon in a 70℃ water bath for 2h. The impregnation bath ratio is 1:20.

[0063] S4. Padding finishing: Use a small vertical padder to roll the polylactic acid ribbon at a pressure of 2 kPa, a speed of 10 r / min, and a rolling rate of 100%; after rolling, place the polylactic acid ribbon in a 90 ° C oven to dry for 3 minutes, and then place it in a shaping dryer at 160 ° C for 3 minutes.

[0064] The polylactic acid ribbons prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were tested: 1. Degradability was tested using the soil burial method according to the national standard GB / T 20197-2006. The degradation performance of the Examples and Comparative Examples was characterized by weight loss. Before placing the material sample in the soil, it was cleaned and dried, and the mass G was recorded. At the corresponding degradation time point, the sample was removed, cleaned and dried, and the mass G0 was recorded. The weight loss rate was calculated according to the formula: Weight loss rate (%) = (G - G0) / G. Where G is the initial mass of the material sample, and G0 is the mass of the material sample after degradation at the corresponding time point, both in grams (g). The results are shown in Table 1 below.

[0065] Table 1

[0066] As can be seen from the data in the table above, the weight loss rate of the example samples after 180 days is close to 60%, while the weight loss rate of the comparative example samples is less than 40%. In the comparative example, traditional flame retardants are applied to the polylactic acid webbing, which easily accumulates in the soil and is difficult to degrade, posing ecological and health risks to the community. The flame retardants used in the present invention are all made from biomass raw materials, and the organic components therein can be rapidly degraded by microbial decomposition after the polylactic acid webbing is discarded. Therefore, the present invention can not only improve the environmental performance of polylactic acid webbing, but also promote the recycling of natural resources.

[0067] 2. The limiting oxygen index (LOI) of polylactic acid webbing was tested according to GB / T5454-1997. Flame-retardant polylactic acid webbing was then subjected to a vertical combustion test according to GB / T5455-2014. The results are shown in Table 2 below.

[0068] Table 2

[0069] As shown in Table 2, the biomass flame retardant of the present invention can significantly inhibit the dripping phenomenon of polylactic acid. The present invention uses two biomass flame retardants, ammonium phytate and ammonium alginate, for a sequential dip-pad and coating flame retardant finish on the polylactic acid webbing. Compared to the dip-pad and bake finish with ammonium polyphosphate or aluminum hydroxide, the limiting oxygen index (LOI) is increased from 27% to over 39%, and the UL-94 vertical combustion resistance is raised from V-2 to V-0. This significantly improves the flame retardant properties of the material sample while maintaining the biodegradability of the polylactic acid webbing.

[0070] Embodiment 4 of the present invention is a flame retardant finishing method for a flame retardant polylactic acid webbing, comprising the following steps: S1. Pretreatment: Place the polylactic acid ribbon in the pretreatment solution, treat it at 75°C for 35 minutes, and then wash and dry it; the pretreatment solution includes 1.5g / L sodium dodecylbenzene sulfonate solution with a mass concentration of 0.2wt% and 0.5g / L sodium carbonate, with a bath ratio of 1:20.

[0071] S2: Corona treatment: The polylactic acid webbing is subjected to corona treatment using a corona discharge apparatus with a treatment voltage of 12 kV and a treatment time of 20 s.

[0072] S3. Impregnation finishing: prepare an impregnation solution with 14g / L ammonium phytate, 5g / L organic montmorillonite and 25g / L isopropyl alcohol, and treat the corona-treated polylactic acid ribbon in an 80°C water bath for 1.5h. The impregnation bath ratio is 1:10.

[0073] S4. Padding finishing: Use a small vertical padder to roll the polylactic acid ribbon at a pressure of 1.8 kPa, a speed of 8 r / min, and a rolling rate of 100%; after rolling, place the polylactic acid ribbon in a 90°C oven to dry for 3 minutes, and then place it in a shaping dryer at 160°C for 3.5 minutes.

[0074] S5. Coating finishing: water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate are mixed in a ratio of 86:12:1:1 to prepare a 12 wt% flame retardant adhesive solution. Use a blender to mix the components evenly, and then pour the adhesive solution into the adhesive tank of an automatic coating machine to form a flame retardant coating on the surface of the polylactic acid webbing.

[0075] S6. Place the polylactic acid ribbon after the flame retardant coating into an oven and pre-bake it at 75°C for 5 minutes, then heat it to 95°C and bake it for 30 minutes. Finally, take it out and cool it at room temperature for 24 hours to allow the solvent to fully evaporate and solidify.

[0076] Embodiment 5 of the present invention is a flame retardant finishing method for a flame retardant polylactic acid webbing, comprising the following steps: S1. Pretreatment: Place the polylactic acid ribbon in a pretreatment solution, treat it at 85°C for 25 minutes, and then wash and dry it; the pretreatment solution includes 2.5g / L sodium dodecylbenzene sulfonate solution with a mass concentration of 0.1wt% and 1.5g / L sodium carbonate, with a bath ratio of 1:20.

[0077] S2: Corona treatment: The polylactic acid webbing is subjected to corona treatment using a corona discharge apparatus with a treatment voltage of 8 kV and a treatment time of 15 s.

[0078] S3. Impregnation finishing: prepare an impregnation solution with 8g / L ammonium phytate, 4g / L organic montmorillonite and 20g / L isopropyl alcohol, and treat the corona-treated polylactic acid ribbon in a 70°C water bath for 2.5h. The impregnation bath ratio is 1:10.

[0079] S4. Padding finishing: Use a small vertical padder to roll the polylactic acid ribbon at a pressure of 2.2 kPa, a speed of 12 r / min, and a rolling rate of 100%; after rolling, place the polylactic acid ribbon in a 90°C oven to dry for 3 minutes, and then place it in a shaping dryer at 170°C for 2.5 minutes.

[0080] S5. Coating finishing: water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate are mixed in a ratio of 88:10:1:1 to prepare a 10wt% flame retardant adhesive solution. Use a blender to mix the components evenly, and then pour the adhesive solution into the adhesive tank of an automatic coating machine to form a flame retardant coating on the surface of the polylactic acid webbing.

[0081] S6. Place the polylactic acid ribbon after the flame retardant coating into an oven and pre-bake it at 85°C for 3 minutes, then heat it to 105°C and bake it for 25 minutes. Finally, take it out and cool it at room temperature for 24 hours to allow the solvent to fully evaporate and solidify.

[0082] Example 6 of the present invention is: a flame-retardant polylactic acid webbing prepared by the flame-retardant finishing method of Example 1.

[0083] In summary, the flame retardant finishing method of the flame retardant polylactic acid webbing provided by the present invention uses two biomass flame retardants, ammonium phytate and ammonium alginate, to perform a dipping and rolling flame retardant finishing and a coating flame retardant finishing in sequence, which not only gives the polylactic acid webbing excellent flame retardant properties, but also maintains the degradable properties of the polylactic acid fiber.

[0084] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the description of the present invention, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A flame retardant finishing method for flame retardant polylactic acid webbing, characterized in that: The following steps are involved: The PLA webbing is sequentially subjected to impregnation finishing, padding finishing and coating finishing; The impregnation liquid for the impregnation finishing comprises ammonium phytate, organic montmorillonite and isopropyl alcohol; The coating finishing comprises the steps of mixing water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate to prepare a flame retardant adhesive solution, and coating the surface of the polylactic acid ribbon with the flame retardant adhesive solution.

2. The flame retardant finishing method of flame retardant polylactic acid webbing according to claim 1, characterized in that: The method also includes the steps of sequentially performing pre-treatment and corona treatment before the polylactic acid webbing is subjected to dipping and finishing.

3. The flame retardant finishing method of flame retardant polylactic acid webbing according to claim 2, characterized in that: The pre-treatment is specifically as follows: placing the polylactic acid ribbon into a pre-treatment solution and treating it at 75-85° C. for 25-35 minutes; The pretreatment liquid includes 1.5-2.5 g / L sodium dodecylbenzenesulfonate solution and 0.5-1.5 g / L sodium carbonate.

4. The flame retardant finishing method of flame retardant polylactic acid webbing according to claim 2, characterized in that: The voltage of the corona treatment is 6-12 kV.

5. The flame retardant finishing method of flame retardant polylactic acid webbing according to claim 1, characterized in that: The impregnation solution includes 6-14 g / L ammonium phytate, 3-5 g / L organic montmorillonite and 15-25 g / L isopropyl alcohol.

6. The flame retardant finishing method of flame retardant polylactic acid webbing according to claim 1, characterized in that: The temperature of the impregnation finishing is 60-80° C., and the time is 1.5-2.5 hours.

7. The flame retardant finishing method of flame retardant polylactic acid webbing according to claim 1, characterized in that: The padding finishing comprises the following steps: rolling the polylactic acid ribbon under the conditions of a pressure of 1.8-2.2 kPa, a rotation speed of 8-12 r / min and a rolling rate of 80-100%.

8. The flame retardant finishing method of flame retardant polylactic acid webbing according to claim 1, characterized in that: The mass ratio of water-soluble polyurethane, ammonium alginate, isocyanate and ethyl acetate in the flame retardant adhesive is 86-90:8-12:1:

1.

9. The flame retardant finishing method of flame retardant polylactic acid webbing according to claim 1, characterized in that: After the coating is finished, the polylactic acid ribbon is kept at 75-85° C. for 3-5 minutes, then heated to 95-105° C. for 20-30 minutes, and then cooled and allowed to stand at room temperature.

10. A flame retardant polylactic acid webbing prepared by the flame retardant finishing method of a flame retardant polylactic acid webbing according to any one of claims 1 to 9.

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