A toughened starch-based single-component intumescent flame retardant, and a preparation method and application thereof

Abstract

The application discloses a toughened starch-based single-component intumescent flame retardant and a preparation method and application thereof. The method is to use starch, hexaphosphate, amino acid and other substances as raw materials to prepare the toughened starch-based single-component intumescent flame retardant through a hydrothermal one-pot method. The preparation method is simple, the synthesis condition is mild, most of the raw materials are renewable biomass materials, and the method is green, environment-friendly and pollution-free. The prepared starch-based single-component intumescent flame retardant is good in thermal stability, high in flame-retardant efficiency, excellent in anti-dripping and smoke suppression performance, excellent in mechanical performance, small in particle size and good in compatibility with polylactic acid, can retain the degradation capacity of polylactic acid itself, effectively realizes the toughening of the polylactic acid material, and greatly expands the application range of the polylactic acid material.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable and flame-retardant composite materials technology, specifically relating to a toughened starch-based single-component intumescent flame retardant, its preparation method, and its application. Background Technology

[0002] In recent decades, with the rapid development of the polymer industry, high-molecular polymers, represented by plastics, rubber, and fibers, have been widely used in all aspects of life. While enjoying the convenience brought by polymer materials, people have also brought about a serious environmental problem—white pollution. Traditional polymers have a degradation cycle of up to hundreds of years under natural conditions, and degradation also brings serious chemical pollution. Therefore, promoting a biodegradable biomass polymer material has become an increasingly urgent task. Among the currently mainstream biodegradable polymer materials, polylactic acid (PLA) is widely used in electronics, textiles, packaging, 3D printing, medical, and building materials due to its good mechanical properties, ease of processing, high transparency, non-toxicity, good biocompatibility, and biodegradability.

[0003] PLA is a thermoplastic biodegradable plastic based on biomass, polymerized from lactic acid monomers. Currently, lactic acid is mostly obtained through bio-fermentation, making PLA a truly biodegradable plastic. However, due to the ester bonds in PLA easily breaking when exposed to fire, and the molecular chain structure leading to the release of flammable volatile substances, the limiting oxygen index of pure PLA is only 19.5%. This significantly limits PLA's application in fields with high flame retardancy requirements, such as electronics, automotive, and building materials. Therefore, flame-retardant modification of PLA is a crucial step in expanding its widespread applications.

[0004] Traditional PLA flame retardants include halogenated flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, and metal compound flame retardants. With the increasing national emphasis on environmental protection and green development, environmentally harmful flame retardants such as halogenated flame retardants have been banned. They have been replaced by intumescent flame retardants composed of carbon sources, acid sources, and gas sources. Among these, biomass-based intumescent flame retardants are widely favored due to their advantages such as being environmentally friendly, requiring low dosage, and having good compatibility with the PLA matrix. Summary of the Invention

[0005] The purpose of this invention is to provide a toughened starch-based single-component intumescent flame retardant, its preparation method, and its application. The synthesis process of this flame retardant is green and environmentally friendly, the reaction conditions are mild, and the operation is simple. Moreover, this flame retardant has good compatibility with PLA matrix and can effectively improve the flame retardant, smoke suppression, anti-dripping, degradability, and toughening properties of polylactic acid, which is of great significance for the promotion and use of PLA materials.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A toughened starch-based one-component intumescent flame retardant, the preparation method of which includes the following steps:

[0008] (1) Add water-soluble starch to deionized water and disperse it evenly by stirring and ultrasonic vibration to obtain a starch suspension;

[0009] (2) Add an appropriate amount of dilute acid solution to the starch suspension obtained in step (1), stir and react for 4 hours in a nitrogen atmosphere at 45°C, and then wash, filter and vacuum dry to obtain soluble starch.

[0010] (3) Grind the soluble starch obtained in step (2) and disperse it in deionized water, then heat it to 90°C and stir it to completely dissolve it to obtain a starch solution;

[0011] (4) The starch solution obtained in step (3) is ultrasonically heated to 90°C, and hexavalent phosphate and acetic anhydride are slowly added dropwise under stirring. After the addition is complete, the mixture is ultrasonicated for 1.0-1.5 h, and then stirred at 90°C for 7.0-10.0 h to obtain phosphated starch solution.

[0012] (5) Add an appropriate amount of amino acids to the phosphated starch solution obtained in step (4), and stir the reaction at 70°C for 12.0-18.0 h to obtain an amino acid phosphated starch solution;

[0013] (6) Add an appropriate amount of Al-containing solution to the amino acid phosphating starch solution obtained in step (5). 3+ The compound was further reacted with stirring at 70°C for 7.0-10.0 h.

[0014] (7) Add sodium carbonate solution to the reaction solution in step (6), adjust the pH to neutral, let it stand for 12 hours to precipitate, and then wash, filter, vacuum dry, crush and sieve to obtain the toughened starch-based single-component intumescent flame retardant.

[0015] Furthermore, the water-soluble starch mentioned in step (1) is any one of potato starch, corn starch, wheat starch, sweet potato starch, etc.

[0016] Furthermore, the amount of dilute acid solution used in step (2) is calculated based on 100-200 mL per 10 g of water-soluble starch; the concentration of the dilute acid solution is 2-3 wt%, and the acid used is one of formic acid, hydrochloric acid, or citric acid.

[0017] Furthermore, the dissolution temperature of the soluble starch obtained in step (2) is 90-95℃.

[0018] Furthermore, the hexaphosphate mentioned in step (4) is sodium hexametaphosphate and / or sodium inositol hexaphosphate.

[0019] Further, the amino acid mentioned in step (5) is one or more of tryptophan, threonine, glycine, alanine, glutamic acid, and arginine.

[0020] Furthermore, the Al-containing component mentioned in step (6) 3+ The compound is one or more of aluminum nitrate, aluminum sulfate, aluminum hydroxide, and aluminum chloride.

[0021] Furthermore, for every 10g of water-soluble starch, use 0.02-0.1mol of hexavalent phosphate, 10-15mL of acetic anhydride, 0.06-0.3mol of amino acids, and 0.02-0.1mol of Al-containing... 3+ Compounds.

[0022] Furthermore, the frequency of the ultrasonic vibration described in steps (1) and (4) is 40 kHz.

[0023] Furthermore, the stirring speed in steps (1)-(6) is 300-500 rpm.

[0024] Furthermore, the concentration of the sodium carbonate solution in step (7) is 5 wt%.

[0025] The starch-based single-component intumescent flame retardant prepared above can be used to prepare toughened flame-retardant polylactic acid. Specifically, the toughened starch-based single-component intumescent flame retardant is mixed with polylactic acid at a mass ratio of 90:10, and then extruded through a twin-screw extruder and injection molded to obtain toughened flame-retardant polylactic acid.

[0026] Starch is polymerized from glucose monomers and is a high-carbon, multi-hydroxyl polysaccharide. When it burns, it forms a large amount of char layer, and the hydroxyl groups it contains catalyze the char layer to become denser, reducing the entry of outside air into the interior. It also hinders the mass and heat transfer process during PLA combustion, which can effectively reduce the combustion characteristics of PLA. Therefore, it can be used as a good biomass carbon source for intumescent flame retardants.

[0027] Sodium hexametaphosphate is readily soluble in water and is a white crystalline solid. It is primarily used in the food industry as a quality improver, pH adjuster, metal ion chelating agent, binder, and leavening agent. The phosphoric acid and hydroxyl groups in sodium hexametaphosphate can accelerate the dehydration of carbon sources to form a dense char layer. Simultaneously, the phosphate groups also form a phosphorus pentoxide protective layer after combustion, serving a similar function to the char layer. Therefore, it can be used as a good acid source for intumescent flame retardants.

[0028] Sodium inositol hexaphosphate contains six phosphate groups and has a phosphorus content as high as 28%. During PLA combustion, the phosphoric acid and hydroxyl groups in sodium inositol hexaphosphate can accelerate the dehydration of the carbon source to form a dense char layer. At the same time, the phosphate groups also form a phosphorus pentoxide protective layer after combustion, which plays a similar role to the char layer. Therefore, it can be used as a good biomass acid source for intumescent flame retardants.

[0029] Amino acids are a class of substances widely distributed in animals and plants. Their structure contains an amino group, which can react with acidic solutions under certain conditions. Furthermore, the amino group in amino acids produces many inert gases during combustion, which can effectively reduce the concentration of flammable substances produced by the thermal decomposition of PLA and also have a good smoke-suppressing effect. Therefore, they can serve as a good biomass nitrogen source for intumescent flame retardants.

[0030] This invention proposes a method for chemically modifying starch with hexaphosphate, amino acids, and aluminum ions, and using ultrasonic vibration, catalyst catalysis, and pH control to increase the grafting degree of phosphorus and nitrogen elements onto starch. The resulting starch-based single-component intumescent flame retardant, which combines carbon, acid, and nitrogen sources, is directly generated via a hydrothermal one-pot process.

[0031] The significant advantages of this invention are:

[0032] (1) All synthesis steps of the present invention are carried out in the aqueous phase and the hydrothermal one-pot method is adopted. The desired product can be obtained directly without separating intermediate products. The preparation process is simple, the reaction conditions are mild, and it is easy to realize industrial production.

[0033] (2) The starch-based single-component intumescent flame retardant prepared by the present invention has good thermal stability and good compatibility with PLA matrix. It can be well dispersed in PLA matrix. Only a small amount of addition is needed to achieve high-efficiency flame retardancy, so that its flame retardancy level reaches UL94V-0. At the same time, it can effectively improve its anti-dripping and smoke suppression effects.

[0034] (3) The high-toughness, fully biodegradable flame-retardant polylactic acid composite material prepared by the starch-based single-component intumescent flame retardant obtained in this invention has good mechanical properties. The tensile strength and elongation at break are improved compared with pure PLA, and the impact strength is greatly improved.

[0035] (4) All raw materials used in this invention are fully biodegradable materials, which do not damage or pollute the environment, and do not affect the degradation performance of the PLA matrix itself, thus achieving a balance between flame retardancy and biodegradability. Attached Figure Description

[0036] Figure 1 The process diagram for preparing the toughened starch-based single-component intumescent flame retardant in Example 1 is shown.

[0037] Figure 2 The image shows the FT-IR spectrum of the toughened starch-based single-component intumescent flame retardant prepared in Example 1.

[0038] Figure 3 SEM images (B) of the char layer after combustion of the flame retardant (A) prepared in Example 1 and the sample prepared in Application Example 1.

[0039] Figure 4 The image shows the SEM images (B) of the char layer after combustion of the flame retardant (A) prepared in Example 2 and the sample prepared in Application Example 2.

[0040] Figure 5 SEM image of the carbon layer after combustion of the sample prepared in Example 1 for comparison.

[0041] Figure 6 SEM image of the carbon layer after combustion of the sample prepared in Example 2.

[0042] Figure 7 SEM images of the char layer after combustion of the sample prepared in Example 3 are shown for comparison. Detailed Implementation

[0043] A toughened starch-based one-component intumescent flame retardant, the preparation method of which includes the following steps:

[0044] (1) Take 10g of water-soluble starch and add it to deionized water. Disperse it evenly by stirring at 300-500 rpm and ultrasonic vibration at 40KHz to obtain a starch suspension.

[0045] (2) Add 100-200 mL of a 2-3 wt% dilute acid solution to the starch suspension obtained in step (1), stir and react at 300-500 rpm for 4 h in a nitrogen atmosphere at 45 °C, and then wash, filter and vacuum dry to obtain soluble starch.

[0046] (3) Grind the soluble starch obtained in step (2) and disperse it in deionized water, then heat it to 90°C and stir it at 300-500 rpm to completely dissolve it, thus obtaining a starch solution;

[0047] (4) Place the starch solution obtained in step (3) in an ultrasonic cleaner, heat it to 90°C, and slowly add 0.02-0.1 mol of hexavalent phosphate and 10-15 mL of acetic anhydride dropwise using a constant pressure funnel while stirring rapidly with a mechanical stirrer. After the addition is complete, sonicate for 1.0-1.5 h, and then continue to stir at 300-500 rpm at 90°C for 7.0-10.0 h to obtain a phosphated starch solution.

[0048] (5) Add 0.06-0.3 mol of amino acids to the phosphated starch solution obtained in step (4), and stir at 300-500 rpm at 70℃ for 12.0-18.0 h to obtain an amino acid phosphated starch solution;

[0049] (6) Add 0.02-0.1 mol of Al-containing compound to the amino acid phosphating starch solution obtained in step (5). 3+ The compound was further reacted at 70°C with stirring at 300-500 rpm for 7.0-10.0 h.

[0050] (7) Add 5 wt% sodium carbonate solution to the reaction solution in step (6), adjust the pH to neutral, let it stand for 12 hours to precipitate, and then wash, filter, vacuum dry, crush and sieve to obtain the toughened starch-based single-component intumescent flame retardant.

[0051] The water-soluble starch is any one of potato starch, corn starch, wheat starch, sweet potato starch, etc. The acid used is one of formic acid, hydrochloric acid, and citric acid. The hexaphosphate is sodium hexametaphosphate and / or sodium inositol hexaphosphate. The amino acid is one or more of tryptophan, threonine, glycine, alanine, glutamic acid, and arginine. The Al-containing... 3+ The compound is one or more of aluminum nitrate, aluminum sulfate, aluminum hydroxide, and aluminum chloride.

[0052] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0053] Example 1:

[0054] Weigh 5g (0.03mol) of potato starch and add it to a 250mL beaker containing 150mL of deionized water. Disperse the starch evenly using magnetic stirring (500rpm, the stirring speed will be the same throughout) and ultrasonic vibration at 40kHz to obtain a starch suspension. Weigh 2.67g (0.014mol) of citric acid and dissolve it in 97.33mL of deionized water to prepare a 2.67% citric acid solution. Add this solution to the obtained starch suspension and stir at 45℃ under nitrogen atmosphere for 4 hours. After washing, filtration, and vacuum drying, obtain soluble starch. Grind the obtained soluble starch and disperse it in 100mL of deionized water. Heat to 90℃ and stir until dissolved to obtain a starch solution. 18.5 g (0.02 mol) of sodium inositol hexaphosphate and 7 mL of acetic anhydride were weighed and added to the obtained starch solution. The mixture was stirred and dispersed, and sonicated for 1.0 h. Then, the mixture was stirred and reacted at 70 °C for 10.0 h. Next, 6.13 g (0.03 mol) of tryptophan was added to the solution, and the mixture was stirred and reacted at 70 °C for 12.0 h. Then, 13.2 g (0.02 mol) of aluminum sulfate was added to the solution, and the mixture was stirred and reacted at 70 °C for 8.0 h. Finally, 5 wt% sodium carbonate solution was added to the solution to adjust the pH to neutral. After standing for 12 h to precipitate, the mixture was washed, filtered, vacuum dried, pulverized, and passed through a 200-mesh sieve to obtain a toughened starch-based single-component intumescent flame retardant.

[0055] Example 2:

[0056] 5 g (0.03 mol) of corn starch was weighed and added to a 250 mL beaker containing 150 mL of deionized water. The starch was dispersed evenly by magnetic stirring and ultrasonic vibration to obtain a starch suspension. 20 mL of 3 wt% hydrochloric acid solution was added to the starch suspension, and the mixture was stirred at 45 °C for 4 h under nitrogen atmosphere. After washing, filtration, and vacuum drying, soluble starch was obtained. The obtained soluble starch was ground and dispersed in 100 mL of deionized water, heated to 90 °C, and stirred until dissolved to obtain a starch solution. 12.2 g (0.02 mol) of sodium hexametaphosphate and 7 mL of acetic anhydride were weighed and added to the obtained starch solution. The mixture was stirred and dispersed, and sonicated for 1.0 h. Then, the mixture was stirred and reacted at 70 °C for 10.0 h. Next, 4.41 g (0.03 mol) of glutamic acid was added to the solution, and the mixture was stirred and reacted at 70 °C for 12.0 h. Then, 2.34 g (0.03 mol) of aluminum hydroxide was added to the solution, and the mixture was stirred and reacted at 70 °C for 8.0 h. Finally, 5 wt% sodium carbonate solution was added to the solution to adjust the pH to neutral. After standing for 12 h to precipitate, the mixture was washed, filtered, vacuum dried, pulverized, and passed through a 200-mesh sieve to obtain a toughened starch-based single-component intumescent flame retardant.

[0057] Application Example 1:

[0058] Weigh 10 parts (by weight) of the starch-based single-component intumescent flame retardant prepared in Example 1, mix it with 90 parts (by weight) of PLA, extrude it through a twin-screw extruder and injection mold it to obtain standard specimens for vertical burning (UL-94), limiting oxygen index (LOI), tensile and impact tests.

[0059] Application Example 2

[0060] Weigh 10 parts (by weight) of the starch-based single-component intumescent flame retardant prepared in Example 2 and 90 parts (by weight) of PLA, stir and mix them evenly, extrude them through a twin-screw extruder and injection mold them to obtain standard specimens for vertical burning (UL-94), limiting oxygen index (LOI), tensile and impact tests.

[0061] Compare with Example 1 (pure sample)

[0062] Polylactic acid granules were injection molded to obtain standard specimens for vertical burning (UL-94), limiting oxygen index (LOI), tensile, and impact testing.

[0063] Comparative Example 2 (Starch)

[0064] Weigh 10 parts (by weight) of potato starch and mix it with 90 parts (by weight) of PLA. Then, extrude the mixture through a twin-screw extruder and injection mold it to obtain standard specimens for vertical burning (UL-94), limiting oxygen index (LOI), tensile, and impact testing.

[0065] Comparison Example 3 (Flame retardants on the market)

[0066] Weigh out 10 parts (by weight) of commercially available ammonium polyphosphate (phosphorus content 30%–32%, nitrogen content 14%–16%) flame retardant, 5 parts (by weight) of potato starch and 85 parts (by weight) of PLA, mix them thoroughly, extrude them through a twin-screw extruder and injection mold them to obtain standard specimens for vertical burning (UL-94), limiting oxygen index (LOI), tensile and impact tests.

[0067] The vertical combustion specimens, limiting oxygen index specimens, tensile specimens, and impact specimens prepared above were tested for combustion performance and mechanical properties in accordance with ASTM D3801, ASTM D2863-97, GB / T 1843-2008, and GB / T 1843-2008. The test results are shown in Table 1.

[0068] Table 1 Combustion performance and mechanical properties

[0069]

[0070] As shown in Table 1, the flame retardant and mechanical properties of the materials obtained in Application Example 1 and Application Example 2 are quite similar. Compared with Comparative Example 1, both flame retardant and mechanical properties are significantly improved, with the limiting oxygen index increasing by about 61%; the UL-94 vertical flammability rating also improving from NR to V-0; and the impact strength, elongation at break, and tensile strength increasing by 35%, 3.0%, and 39%, respectively. While maintaining the high tensile strength of polylactic acid (PLA) materials, the toughening of PLA materials is also effectively achieved.

[0071] As can be seen from the comparison with Examples 2 and 3, the material prepared in the application example has higher flame retardant efficiency and also improves the mechanical properties of polylactic acid, realizing the multifunctional modification of polylactic acid materials.

[0072] Figure 2 The image shows the FI-IR spectrum of the starch-based one-component intumescent flame retardant prepared in Example 1. As can be seen in the image, compared to pure starch, the starch-based one-component intumescent flame retardant exhibits five new peaks in its infrared spectrum, with peaks at 3630 cm⁻¹. -1 1150cm -1 3530cm -1 1520cm -1 and 486cm -1 This corresponds to the hydroxyl group and -OP- bond of sodium inositol hexaphosphate, the hydroxyl group on starch, and the NH3 group on tryptophan. + And the Al-O bond, which indicates that sodium inositol hexaphosphate, tryptophan and Al 3+ All were successfully grafted onto starch.

[0073] Figure 3 , 4 SEM images (A) of the flame retardants prepared in Examples 1 and 2, and SEM image (B) of the char layer after combustion of the prepared samples from the application example, are shown respectively. As can be seen from the figures, the obtained flame retardants have a microscopic morphology of small spheres, thus they can be well dispersed in the PLA matrix, thereby improving the mechanical properties of the PLA composite material. The char layer after combustion is dense and compact, which can effectively isolate heat and mass transfer, resulting in a good flame retardant effect.

[0074] Figure 5-7 The images show SEM images of the char layer after combustion of polylactic acid samples prepared in Comparative Examples 1-3. As can be seen from the images, the char layer has many pores, which fails to adequately block the heat source, thus failing to achieve the desired flame-retardant effect.

[0075] The above examples show that:

[0076] (1) Most of the raw materials used in the toughened starch-based single-component intumescent flame retardant prepared in this invention are fully biodegradable materials that can degrade into non-toxic and harmless small molecules under natural conditions. The addition of the toughened starch-based single-component intumescent flame retardant to the polylactic acid matrix in this invention will not affect its degradation performance. On the contrary, it can accelerate the natural degradation rate of polylactic acid to a certain extent. This is because sodium inositol hexaphosphate and sodium hexametaphosphate have good hydrophilicity, which can improve the water absorption performance of polylactic acid. Under natural conditions, they can more easily catalyze the ester bond breakage in polylactic acid. At the same time, starch, amino acids and other substances can be decomposed and utilized by microorganisms, further accelerating the degradation of the polylactic acid matrix.

[0077] (2) The toughening starch-based single-component intumescent flame retardant prepared in this invention is microspheres with very small particle size, which can be well dispersed in the polylactic acid matrix. At the same time, the raw materials used, such as starch, hexavalent phosphate, and amino acids, will form intermolecular hydrogen bonds with the active groups in the polylactic acid matrix. This makes the obtained flame-retardant polylactic acid composite material not only maintain high tensile strength but also improve its toughness, making an important contribution to the wider application of polylactic acid materials.

[0078] (3) The flame retardant prepared by the present invention is a biomass-based material with good compatibility with polylactic acid material and is well dispersed in polylactic acid matrix. Therefore, it can achieve effective flame retardancy with only a small amount of addition. At the same time, the introduction of aluminum ions effectively suppresses the emission of molten droplets and dense smoke during combustion.

[0079] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. The application of a starch-based single-component intumescent flame retardant in the preparation of toughened flame-retardant polylactic acid, characterized in that, The preparation of the starch-based single-component intumescent flame retardant includes the following steps: (1) Add water-soluble starch to deionized water and disperse it evenly by stirring and ultrasonic vibration to obtain a starch suspension; (2) Add dilute acid solution to the starch suspension obtained in step (1), stir and react for 4 hours in a nitrogen atmosphere at 45°C, and then wash, filter and vacuum dry to obtain soluble starch; (3) Grind the soluble starch obtained in step (2) and disperse it in deionized water, then heat it to 90°C and stir it to completely dissolve it to obtain a starch solution; (4) The starch solution obtained in step (3) is ultrasonically heated to 90°C, and hexavalent phosphate and acetic anhydride are slowly added dropwise under stirring. After the addition is complete, the mixture is ultrasonicated for 1.0-1.5 h, and then stirred at 90°C for 7.0-10.0 h to obtain phosphated starch solution. (5) Add amino acids to the phosphated starch solution obtained in step (4) and stir at 70°C for 12.0-18.0 h to obtain an amino acid phosphated starch solution; (6) Add an Al-containing solution to the amino acid phosphating starch solution obtained in step (5). 3+ The compound was further reacted with stirring at 70°C for 7.0-10.0 h. (7) Add sodium carbonate solution to the reaction solution in step (6), adjust the pH to neutral, let it stand for 12 hours to precipitate, and then wash, filter, vacuum dry, crush and sieve to obtain the starch-based single-component intumescent flame retardant. The hexaphosphate mentioned in step (4) is sodium hexametaphosphate and / or sodium inositol hexaphosphate; The amino acid mentioned in step (5) is one or more of tryptophan, threonine, glycine, alanine, and glutamic acid.

2. The application according to claim 1, characterized in that: The water-soluble starch mentioned in step (1) is any one of potato starch, corn starch, wheat starch, and sweet potato starch.

3. The application according to claim 1, characterized in that: The amount of dilute acid solution used in step (2) is calculated based on 100-200 mL per 10 g of water-soluble starch; the concentration of the dilute acid solution is 2-3 wt%, and the acid used is one of formic acid, hydrochloric acid, or citric acid.

4. The application according to claim 1, characterized in that: The Al-containing step (6) 3+ The compound is one or more of aluminum nitrate, aluminum sulfate, aluminum hydroxide, and aluminum chloride.

5. The application according to claim 1, characterized in that: For every 10g of water-soluble starch, use 0.02-0.1mol of hexavalent phosphate, 10-15mL of acetic anhydride, 0.06-0.3mol of amino acids, and 0.02-0.1mol of Al-containing... 3+ Compounds.

6. The application according to claim 1, characterized in that: The concentration of the sodium carbonate solution in step (7) is 5 wt%.

7. The application according to claim 1, characterized in that: The starch-based single-component intumescent flame retardant was mixed with polylactic acid at a mass ratio of 90:10, and then extruded and injection molded to obtain toughened flame-retardant polylactic acid.

Images