Preparation method of sericin-based bio-based flame retardant and application of sericin-based bio-based flame retardant to cellulose fabric

Abstract

The invention discloses a preparation method of a sericin-based bio-based flame retardant and application of the sericin-based bio-based flame retardant to cellulose fabrics, and belongs to the field of textile assistants. The method comprises the following steps: dissolving waste sericin with hydrochloric acid to prepare a bio-based amino acid solution; a boron-containing monomer pentaerythritol diborate is prepared through an organic synthesis reaction, then the boron-containing monomer pentaerythritol diborate and amino in a bio-based amino acid solution are subjected to a substitution reaction to prepare a bio-based flame retardant, the flame-retardant effect is remarkably enhanced through a boron and nitrogen synergistic flame-retardant mechanism, and the flame-retardant cotton fabric which is environmentally friendly, excellent in flame-retardant performance and good in washing resistance is prepared. The preparation method of the flame retardant is simple, convenient and efficient, cyclic utilization of resources is effectively promoted, and the prepared flame-retardant cellulose fabric has wide application prospects in the fields of vehicle interiors, clothes and furniture.

Description

Technical Field

[0001] The invention relates to the technical field of textile auxiliaries, and in particular to a preparation method of a bio-based flame retardant based on sericin and application of the bio-based flame retardant on cellulose fabrics. Background Art

[0002] In the textile industry, flame retardancy is one of the important indicators for evaluating the safety and durability of fabrics. With the improvement of people's safety awareness and the increasingly stringent environmental regulations, the development of efficient, environmentally friendly and biocompatible flame retardants has become a hot topic in current research. Traditional flame retardants such as halogen flame retardants, although low in price and good in stability, have irreversible effects on the human body and the environment due to the toxic and harmful substances such as hydrogen halides produced after high-temperature decomposition, so their use has been gradually restricted. In contrast, biomass flame retardants have received widespread attention due to their high biocompatibility, non-toxicity and biodegradability.

[0003] In the field of biomass materials, sericin, as a natural protein, is mainly derived from silkworm cocoons, accounting for 20-30% of silk. In the silk processing process, sericin is usually regarded as waste and removed, which not only causes a waste of resources, but also increases the burden of sewage treatment. It is of great significance to study how to achieve the recycling of sericin resources and the sustainable development of the environment.

[0004] Cellulose fabric is a general term for a type of textile whose main fiber component is cellulose, mainly including natural cellulose fabric (such as cotton fabric, linen fabric) and regenerated cellulose fabric (such as viscose fiber fabric, lyocell fiber fabric). It has the advantages of wide source of raw materials, good wearing performance, good environmental degradation performance, etc., and is widely used in clothing, home furnishings, vehicle interiors and other fields. It is very easy to burn when encountering fire, and the burning speed is fast, and the fire spreads quickly. Therefore, the development of efficient, environmentally friendly and durable flame retardants to improve the flame retardant properties of cellulose textiles has become an urgent problem to be solved in order to expand the application scope of cellulose textiles. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a method for preparing a bio-based flame retardant based on sericin and its application on cellulose fabrics. Through reasonable molecular design, the boron flame retardant monomer is introduced into the amino acid matrix structure, and the flame retardant effect of the flame retardant is greatly improved by utilizing the synergistic flame retardant mechanism of boron and nitrogen; the hydrogen bond structure generated by the carboxyl group in the amino acid and the hydroxyl group on the surface of the cotton fabric is utilized to prepare a green, environmentally friendly, flame retardant cotton fabric with excellent flame retardant performance and good water washability.

[0006] The technical solution of the present invention is as follows:

[0007] The first object of the present invention is to provide a method for preparing a bio-based flame retardant based on sericin, comprising the following steps:

[0008] (1) boric acid reacts with pentaerythritol in an organic solvent to prepare pentaerythritol diborate;

[0009] (2) pentaerythritol diborate (TDUD) reacts with a chlorine-containing monomer in an organic solvent to obtain a chlorine-terminated flame retardant monomer;

[0010] (3) reacting the chlorine-terminated flame retardant monomer with an amino acid hydrolyzate to obtain the bio-based flame retardant;

[0011] The amino acid hydrolyzate is prepared by acid hydrolysis of sericin.

[0012] In one embodiment of the present invention, in step (1), the molar ratio of boric acid to pentaerythritol is 2-3:1; the reaction temperature is 100-120° C., and the reaction time is 6-8 h.

[0013] In one embodiment of the present invention, in step (1), the organic solvent is one or more of benzene, toluene, and xylene.

[0014] In one embodiment of the present invention, in step (1), the specific steps are:

[0015] Boric acid and pentaerythritol are dissolved in an organic solvent, stirred at high temperature, connected to an oil-water separator, and reacted until no water is generated. After the reaction is completed, the organic solvent is removed to obtain a white powdery boron-containing flame retardant monomer, namely pentaerythritol diborate.

[0016] In one embodiment of the present invention, in step (2), the chlorine-containing monomer is one or more of phosphorus oxychloride, cyanuric chloride, phenylphosphonic dichloride, and hexachlorocyclotriphosphazene.

[0017] In one embodiment of the present invention, in step (2), the molar ratio of pentaerythritol diborate to chlorine-containing monomer is 1:1-2; the reaction temperature is 75-90° C., and the reaction time is 4-6 h.

[0018] In one embodiment of the present invention, in step (2), the organic solvent is one or more of acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, and tetrahydrofuran.

[0019] In one embodiment of the present invention, in step (2), the specific steps are:

[0020] Pentaerythritol diborate is dissolved in an organic solvent, a chlorine-containing monomer is added, and the mixture is stirred at high temperature. After the reaction is completed, the solvent is removed to obtain a chlorine-terminated flame-retardant monomer.

[0021] In one embodiment of the present invention, in step (3), the preparation method of the amino acid hydrolyzate is: adding silkworm cocoon waste sericin protein to a hydrochloric acid solution, reflux reaction at 90-120° C. for 20-30 hours, filtering, and obtaining an amino acid hydrolyzate; and measuring the content of free amino groups in the hydrolyzate by the o-phthalaldehyde method to be 0.25-0.35 mol / L.

[0022] In an embodiment of the present invention, the concentration of the hydrochloric acid solution is 5-8 M; the mass volume ratio of sericin to the hydrochloric acid solution is 1:5 g / mL.

[0023] In one embodiment of the present invention, in step (3), the molar ratio of the chlorine-terminated flame retardant monomer to the amino group in the amino acid hydrolyzate is 1:1.

[0024] In one embodiment of the present invention, the conditions for the reaction of the chlorine-terminated flame retardant monomer with the amino acid hydrolyzate are: reaction temperature of 50-70° C., and reaction time of 8-12 h.

[0025] In one embodiment of the present invention, in step (3), the specific steps are:

[0026] The chlorine-terminated flame retardant monomer is added to the amino acid hydrolyzate, stirred at high temperature, and the solvent is removed after the reaction is completed to obtain the bio-based flame retardant.

[0027] The second object of the present invention is to provide a bio-based flame retardant based on sericin prepared by the above preparation method.

[0028] The third object of the present invention is to provide a use of the above bio-based flame retardant for finishing fiber fabrics.

[0029] The fourth object of the present invention is to provide a fiber fabric finished with the above-mentioned bio-based flame retardant, and the finishing method is:

[0030] (1) soaking the cellulose fabric in a sodium hydroxide solution, desizing it at a constant temperature, and then drying it for later use;

[0031] The desizing treatment refers to removing the sizing agent, oil, ester and impurities on the surface of the fabric, destroying the crystal area of ​​the fabric, reducing the crystallinity, and exposing more -OH on the cellulose to the outside;

[0032] (2) dissolving and dispersing the above-mentioned bio-based flame retardant in a water / ethanol mixed solvent to prepare a flame retardant finishing liquid;

[0033] (3) placing the cellulose fabric in step (1) in the flame retardant finishing liquid prepared in step (2), treating it by a two-immersion and two-rolling method, and then drying it in a drying machine to obtain a bio-based flame retardant cellulose fabric.

[0034] In one embodiment of the present invention, in step (1), the cellulose fabric is one or more of cotton fabric, linen fabric, viscose fabric, and lyocell fabric.

[0035] In one embodiment of the present invention, in step (1), the concentration of the sodium hydroxide solution is 80-200 g / L.

[0036] In one embodiment of the present invention, in step (1), the constant temperature is 80-95°C, the treatment time is 1-2h; and the drying temperature is 50-60°C.

[0037] In one embodiment of the present invention, in step (2), the volume ratio of water to ethanol in the water / ethanol mixed solvent is 0.5-1.5:1.

[0038] In one embodiment of the present invention, in step (2), the concentration of the flame retardant finishing liquid is 50-400 g / L.

[0039] In one embodiment of the present invention, in step (3), the bath ratio is 1:10 and the rolling ratio is 60-80%.

[0040] In one embodiment of the present invention, the finished fiber fabric is used to prepare vehicle interior, clothing or furniture fabric.

[0041] The beneficial technical effects of the present invention are:

[0042] (1) The present invention adopts an environmentally friendly strategy, using silkworm cocoon waste sericin as the core raw material, which improves the recycling rate of limited resources and effectively promotes the concept of green environmental protection and sustainable development. This design shows great significance in protecting the ecological environment and promoting resource recycling.

[0043] (2) Compared with the complex preparation process of traditional flame retardants, the present invention simplifies the synthesis path and improves production efficiency; the synthesized bio-based flame retardant exhibits a synergistic flame retardant system that integrates acid source, gas source and carbon source, which can effectively catalyze the formation of a dense carbonized layer on the fabric at high temperature, significantly enhancing the flame retardant properties of the fabric.

[0044] (3) The flame-retardant cellulose fabric prepared by the present invention effectively exerts the condensed phase flame retardant effect of the boron-based flame retardant monomer and the gas phase flame retardant effect of the amino acid matrix, thereby improving the flame retardancy of the cellulose fabric. The total heat release amount and the peak heat release rate are reduced by 50% and 70% respectively compared with ordinary cellulose fabrics.

[0045] (4) The flame-retardant cellulose fabric prepared by the present invention, due to the reasonable molecular design of the flame retardant, retains the carboxyl groups in the amino acid matrix that are easy to form hydrogen bonds or ester groups with the hydroxyl groups in cellulose while ensuring the flame retardant effect of the flame retardant, thereby effectively improving the flame retardant durability of the cellulose flame-retardant fabric. After 25 times of water washing, the limiting oxygen index of the flame-retardant fabric is still maintained above 28%.

[0046] (5) The method of the present invention is simple, efficient, controllable and repeatable. The flame retardant component is green and environmentally friendly, which improves the flame retardant properties of cellulose fabrics and is conducive to the development of functional textiles with flame retardant functions. It overcomes the problem of flammability of textiles and has a wide range of application scenarios in the fields of vehicle interiors, clothing, and furniture. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The molecular formula of the synthesis process of the bio-based flame retardant prepared in Example 1;

[0048] Figure 2 This is a Fourier transform infrared (FTIR) image of the bio-based flame retardant prepared in Example 1;

[0049] Figure 3 The scanning electron microscope (SEM) images of the flame retardant cotton fabric and the ordinary cotton fabric prepared in Example 1;

[0050] Figure 4 The vertical burning digital photos of the flame-retardant cotton fabric and the ordinary cotton fabric prepared in Example 1;

[0051] Figure 5 The limiting oxygen index graphs of flame-retardant cotton fabrics and normal cotton fabrics were prepared for different flame retardant concentrations;

[0052] Figure 6 The heat release rate (HRR) diagram of the flame retardant cotton fabric and the ordinary cotton fabric prepared in Example 1;

[0053] Figure 7 This is a graph of total heat release (THR) of the flame-retardant cotton fabric and ordinary cotton fabric prepared in Example 1. DETAILED DESCRIPTION

[0054] Test method:

[0055] 1. The limiting oxygen index was measured by LFY-606B digital limiting oxygen index tester; the residual carbon length was measured by LFY-601A vertical combustion instrument; the heat release rate and total heat release were measured by micro calorimeter.

[0056] 2. OPA method to measure free amino content:

[0057] (1) Preparation of OPA reagent: dissolve 7.620 g borax and 200 mg sodium dodecyl sulfate (SDS) in 150 mL deionized water; dissolve 160 mg o-phthalaldehyde (OPA) in 4 mL anhydrous ethanol and add to the above solution. After complete dissolution, add 176 mg 1.4-dimercaptothreitol (DTT) and stir until complete dissolution. Use deionized water to make up to 200 mL. This reagent is prepared and used immediately.

[0058] (2) Preparation of glutamic acid standard solution: accurately weigh 50 mg of glutamic acid standard sample, dissolve it in distilled water and make up to 100 mL. The concentration of this solution is 0.5 mg / mL. Dilute it according to the required concentration when using.

[0059] (3) To draw the standard curve, transfer 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, and 6.0 mL of glutamic acid standard solution to 11 100 mL volumetric flasks, and dilute to the scale with deionized water (amino acid content is 0, 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 17.5, 20.0, 25.0, and 30.0 ug / mL). Take 2 mL of the working solution in each test tube, add 2 mL of OPA reagent, and then add 2 mL of phosphate buffer at pH = 8.04. After reacting in the dark for 3 minutes, use a fluorescence photometer to zero with the blank solution at a wavelength of 360 nm, and measure the relative fluorescence intensity of the remaining solutions; use the microgram number of amino acids as the horizontal axis and the relative fluorescence intensity as the vertical axis to draw the standard curve.

[0060] (4) Determination of the amino acid content in the amino acid extract: Take 2.0 mL of the filtrate and measure the relative fluorescence intensity under the same conditions as the standard curve preparation steps, and then calculate the free amino group content based on the standard curve.

[0061] Embodiment 1:

[0062] A method for preparing a bio-based flame retardant based on sericin comprises the following steps:

[0063] (1) Preparation of amino acid hydrolyzate

[0064] 100g of silkworm cocoon waste sericin was added to 500mL of 6M hydrochloric acid solution, and refluxed at 100℃ for 24h, and filtered to obtain amino acid hydrolyzate for use; the content of free amino group in the solution was measured by o-phthalaldehyde method and was 0.3mol / L;

[0065] (2) Preparation of pentaerythritol diborate: 6.801 g (0.11 mol) of boric acid and 6.807 g (0.05 mol) of pentaerythritol were dissolved in 200 mL of toluene. The oil-water separator was connected to a spherical condenser, and the reaction was carried out at 110° C. until no water was produced in the oil-water separator. After the reaction was completed, the toluene solvent was removed by rotary evaporation, and the product was recrystallized with acetone and dried in a vacuum oven at 50° C. to obtain white solid pentaerythritol diborate (TDUD) with a yield of 86%.

[0066] (3) Preparation of chlorine-terminated flame-retardant monomers:

[0067] 18.775 g (0.1 mol) of TDUD was dissolved in 400 mL of tetrahydrofuran, and 15.332 g (0.1 mol) of phosphorus oxychloride was added. The mixture was stirred continuously and the reaction temperature was slowly raised from room temperature to 75°C. The mixture was reacted until no HCl was released. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed with tetrahydrofuran, and dried in a vacuum drying oven at 50°C to obtain a white powdery solid product.

[0068] (4) Preparation of bio-based flame retardants:

[0069] 13.408 g (0.05 mol) of the chlorine-terminated flame retardant monomer obtained in step (3) was dissolved in 50 mL of the amino acid hydrolyzate obtained in step (1), and stirred at 70° C. for 8 hours. After the reaction was completed, the solvent was removed by rotary evaporation, and the mixture was placed in a vacuum drying oven at 50° C. to obtain the bio-based flame retardant.

[0070] The fiber fabric finished with the above bio-based flame retardant is finished by the following method:

[0071] (1) soaking the cotton fabric in a 200 g / L sodium hydroxide solution, desizing it at 90° C. for 2 h, and then drying it at 50° C. for later use;

[0072] (2) dissolving the above bio-based flame retardant in a water / ethanol mixed solvent (the volume ratio of ethanol to water is 1:1) to prepare a flame retardant finishing liquid with a flame retardant concentration of 200 g / L;

[0073] (3) The cotton fabric treated in step (1) is placed in the flame retardant finishing liquid prepared in step (2) at a bath ratio of 1:10, and a wet cotton fabric with a rolling rate of 80% is prepared by a double dipping and double rolling method, and the wet cotton fabric is placed in a drying machine and baked at a high temperature of 150° C. to obtain a flame retardant cotton fabric.

[0074] Figure 1 The schematic diagram of the route for synthesizing the bio-based flame retardant in this embodiment; the bio-based flame retardant prepared in this embodiment was tested by Fourier infrared spectroscopy, and the results are as follows Figure 2 As shown. It can be observed: 3167cm -1 The hydroxyl absorption peak at 2955 cm -1 and 2891cm-1 The absorption peaks at 1293 are methyl and methylene respectively. -1 and 560cm -1 The broad absorption peak at 908 cm-1 is a typical stretching vibration absorption peak of BO. -1 The absorption peak of PO bond is 1727cm -1 and 1129cm -1 The C=O and PN stretching vibration absorption peaks are Figure 1 The synthesized molecular formula is consistent with the structural characteristics, proving that the target product has been successfully synthesized.

[0075] The flame retardant cotton fabric prepared in Example 1 was subjected to scanning electron microscopy, vertical combustion, limiting oxygen index, heat release rate (HRR), and total heat release (THR) tests, and the results were as follows: Figures 3 to 7 The specific performance results are shown in Table 1.

[0076] Table 1

[0077]

[0078] After flame retardant finishing, the vertical burning test showed that the residual carbon length was significantly reduced, the limiting oxygen index was significantly increased, the peak heat release rate was reduced by 73.3%, and the total heat release was reduced by 54.6%.

[0079] The preparation method of the invention is simple and controllable, the flame retardant matrix adopted is green and environmentally friendly, and the prepared flame retardant cotton fabric exhibits excellent flame retardant effect.

[0080] Embodiment 2:

[0081] A fiber fabric finished with a bio-based flame retardant, the finishing method comprising:

[0082] The same as Example 1, except that the concentration of the flame retardant finishing liquid was replaced from 200 g / L to 50 g / L, 100 g / L, 300 g / L, 400 g / L respectively, and other conditions remained unchanged to prepare flame retardant cotton fabrics. The properties of the flame retardant cotton fabrics were measured, and the results are shown in Table 2.

[0083] Table 2

[0084]

[0085] It can be seen that when other conditions remain unchanged, the flame retardant effect improves as the flame retardant concentration increases.

[0086] Embodiment 3:

[0087] A method for preparing a bio-based flame retardant based on sericin comprises the following steps:

[0088] The same as Example 1, except that the chlorine-containing monomer is replaced by cyanuric chloride, phenylphosphonic dichloride, and hexachlorocyclotriphosphazene respectively from phosphorus oxychloride, and other conditions remain unchanged, to prepare a bio-based flame retardant.

[0089] The fiber fabric finished with the above bio-based flame retardant is finished by the following method:

[0090] Same as Example 1. The properties of the flame retardant cotton fabric obtained were measured. The results are shown in Table 3.

[0091] Table 3

[0092]

[0093] It can be seen that when other conditions remain unchanged, the flame retardant properties do not change significantly when the chlorine-containing monomer is replaced from phosphorus oxychloride to other chlorine-containing and phosphorus-containing monomers. When it is replaced with a chlorine-containing but non-phosphorus-containing monomer, the flame retardant effect is slightly reduced.

[0094] Comparative Examples 1-4

[0095] A flame retardant finished fiber fabric, the finishing method is:

[0096] Refer to Example 1, except that the bio-based flame retardant is replaced by pentaerythritol diborate, phosphorus oxychloride, phenylphosphonyl dichloride, and hexachlorocyclotriphosphazene, respectively.

[0097] Comparative Example 5

[0098] A flame retardant finished fiber fabric, the finishing method is:

[0099] Referring to Example 1, the difference is that the bio-based flame retardant is replaced by amino acid hydrolyzate, and the specific steps are as follows:

[0100] Extraction of amino acids: 100 g of silkworm cocoon waste sericin was added to 500 mL of 6 M hydrochloric acid solution, and refluxed at 100 °C for 24 h to obtain amino acid hydrolyzate for use. The content of free amino groups in the solution was measured by o-phthalaldehyde method and was 0.3 mol / L.

[0101] 300 mL of the amino acid hydrolyzate obtained above was placed in a rotary evaporator, and rotary evaporated at 70°C for 3 hours to obtain an amino acid concentrate, which was transferred to a vacuum oven and dried at 60°C; the amino acid powder obtained above was dissolved in a solvent with an ethanol: water volume ratio of 1:1 to obtain an amino acid finishing solution with a concentration of 200 g / L; the cotton fabric was immersed in the flame retardant finishing solution at a bath ratio of 1:10, and a wet cotton fabric with a rolling rate of 80% was obtained by a double dipping and double rolling method, which was placed in a drying machine and baked at a high temperature of 150°C to obtain a flame retardant cotton fabric.

[0102] The properties of the flame retardant cotton fabrics obtained in Comparative Examples 1-5 were measured, and the results are shown in Table 4.

[0103] Table 4

[0104]

[0105]

[0106] It can be seen that when other conditions remain unchanged, the flame retardant finishing liquid is replaced by pentaerythritol diborate from the prepared bio-based flame retardant, the flame retardant performance decreases; when it is replaced by amino acid hydrolyzate, the flame retardant performance decreases significantly; when it is replaced by chlorine-terminated flame retardant monomer, the flame retardant performance increases. This is because chlorine is one of the halogen flame retardant elements. However, chlorine-containing flame retardants will release a large amount of hydrogen chloride gas when burned, causing serious harm to the environment.

[0107] Embodiment 4:

[0108] Flame retardant durability test of flame retardant cotton fabric prepared with amino acid matrix

[0109] The flame retardant cotton fabric prepared in Example 1 was washed 5, 10, 15, 20 and 25 times respectively, and the properties of the flame retardant cotton fabric were measured. The results are shown in Table 5.

[0110] Table 5

[0111]

[0112] It can be seen that with the increase of the number of washing times, the flame retardant properties of the flame retardant cotton fabric gradually decreases. After washing 25 times, the limiting oxygen index is still higher than 28%, showing excellent flame retardant durability.

[0113] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a bio-based flame retardant based on sericin, characterized in that: The steps include: (1) boric acid reacts with pentaerythritol in an organic solvent to prepare pentaerythritol diborate; (2) pentaerythritol diborate reacts with a chlorine-containing monomer in an organic solvent to obtain a chlorine-terminated flame retardant monomer; (3) reacting the chlorine-terminated flame retardant monomer with an amino acid hydrolyzate to obtain the bio-based flame retardant; The amino acid hydrolyzate is prepared by acid hydrolysis of sericin.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of boric acid to pentaerythritol is 2-3:1; the reaction temperature is 100-120° C., and the reaction time is 6-8 hours.

3. The preparation method according to claim 1, characterized in that: In step (2), the chlorine-containing monomer is one or more of phosphorus oxychloride, cyanuric chloride, phenylphosphonyl dichloride, and hexachlorocyclotriphosphazene.

4. The preparation method according to claim 1, characterized in that: In step (2), the molar ratio of pentaerythritol diborate to chlorine-containing monomer is 1:1-2; the reaction temperature is 75-90° C., and the reaction time is 4-6 hours.

5. The preparation method according to claim 1, characterized in that: In step (3), the preparation method of the amino acid hydrolyzate is as follows: adding the silkworm cocoon waste sericin protein to a hydrochloric acid solution, and reflux reacting at 90-120° C. for 20-30 hours to obtain the amino acid hydrolyzate; and the content of free amino groups in the hydrolyzate is measured by the o-phthalaldehyde method and is 0.25-0.35 mol / L.

6. The preparation method according to claim 5, characterized in that: The concentration of the hydrochloric acid solution is 5-8M; the mass volume ratio of sericin to the hydrochloric acid solution is 1:5 g / mL.

7. The preparation method according to claim 1, characterized in that: In step (3), the molar ratio of the chlorine-terminated flame retardant monomer to the amino group in the amino acid hydrolyzate is 1:1; the reaction temperature is 50-70° C., and the reaction time is 8-12 hours.

8. A bio-based flame retardant based on sericin prepared by the preparation method according to any one of claims 1 to 7.

9. An application of the bio-based flame retardant according to claim 8, characterized in that: Used for finishing fiber fabrics.

10. The use according to claim 9, characterized in that: The finished fiber fabrics are used to prepare vehicle interiors, clothing or furniture fabrics.

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