Bio-based flame-retardant decorative film and preparation method thereof

Abstract

The invention discloses a bio-based flame-retardant decorative film and a preparation method thereof. The decorative film is prepared from the following components in percentage by mass: 60.0 to 80.0 percent of bio-based high polymer material, 10.0 to 30.0 percent of composite flame retardant, 2.0 to 10.0 percent of plasticizer, 0.5 to 2.0 percent of stabilizer and 5.0 to 15.0 percent of filler, the composite flame retardant is formed by compounding a first flame retardant and a second flame retardant, the first flame retardant is a nitrogen-phosphorus flame retardant, and the second flame retardant is a flame retardant containing silicon and cage-shaped bicyclic phosphate. The preparation method comprises the following steps: S1, melting the bio-based polymer; s2, stirring the melt and a plasticizer to obtain a mixed material A; s3, adding a flame retardant and a stabilizer into the mixed material A, and stirring to obtain a mixed material B; s4, adding a filler into the mixed material B, and stirring to obtain a mixed material C; s5, extruding the mixed material C to obtain a bio-based flame-retardant decorative film blank; and S6, annealing, cooling and cutting the blank to obtain the bio-based flame-retardant decorative film.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant materials, and in particular to a bio-based flame retardant decorative film and a preparation method thereof. Background Art

[0002] As a new type of environmentally friendly material, the preparation method of bio-based flame retardant decorative film mainly involves the compounding of bio-based polymer materials and flame retardants. At present, bio-based materials have been widely used in packaging, electronics, automobiles and other fields. However, the existing bio-based flame retardant decorative film technology has some limitations, especially in the balance between flame retardant effect and material mechanical properties.

[0003] Traditional bio-based flame-retardant decorative films have deficiencies in flame retardant properties, especially under high temperature conditions, where they are prone to thermal decomposition, resulting in reduced flame retardant effects. In addition, existing methods for preparing bio-based flame-retardant decorative films often have problems such as high costs and complex processes, as well as uneven dispersion of flame retardants, which affects the mechanical properties and decorative effects of the resulting bio-based flame-retardant decorative film materials. Summary of the invention

[0004] The purpose of the present invention is to provide a bio-based flame retardant decorative film and a preparation method thereof to solve the problems of poor flame retardant effect and mechanical properties of traditional bio-based flame retardant decorative films, thereby solving the above problems.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions:

[0006] The present invention provides a bio-based flame-retardant decorative film, which comprises the following components by mass fraction: 60.0-80.0% of bio-based polymer material, 10.0-30.0% of composite flame retardant, 2.0-10.0% of plasticizer, 0.5-2.0% of stabilizer and 5.0-15.0% of filler;

[0007] The composite flame retardant is compounded by a first flame retardant and a second flame retardant. The first flame retardant is a novel nitrogen-phosphorus flame retardant, and the second flame retardant is a flame retardant containing silicon and caged bicyclic phosphate groups.

[0008] Specifically, the preferred composite flame retardant of the present invention has higher flame retardant efficiency and lower toxicity.

[0009] Furthermore, a bio-based flame retardant decorative film: the bio-based polymer material is polylactic acid (PLA) or polybutylene succinate (PBS).

[0010] Furthermore, a bio-based flame retardant decorative film: the first flame retardant is melamine aminotrimethylene phosphate (MATMP).

[0011] Furthermore, a bio-based flame retardant decorative film: the second flame retardant is tris(2,6,7-trioxa-1-phosphobicyclo[2.2.2]octane-1-oxy-4-hydroxymethyl)phenylsilane (TPPSi).

[0012] Furthermore, a bio-based flame retardant decorative film: the first flame retardant in the composite flame retardant accounts for 60.0 to 80.0 wt%.

[0013] Furthermore, a bio-based flame retardant decorative film: the first flame retardant in the composite flame retardant accounts for 70.0wt%.

[0014] Furthermore, a bio-based flame retardant decorative film: the plasticizer is selected from at least one of epoxidized soybean oil (ESO), epoxy oleate, dibutyl sebacate (DBS), and dioctyl sebacate (DOS); the stabilizer is selected from at least one of sorbitol hexaacetate, epigallocatechin gallate (EGCG), rosemary antioxidant, rosemary extract, grape seed extract, and green tea extract; the filler is selected from at least one of talc, mica powder, nano-silica, nano-montmorillonite, wood powder, rice husk powder, graphene, and glass fiber

[0015] The present invention also provides a method for preparing a bio-based flame retardant decorative film, which comprises the following specific steps:

[0016] S1, preheating and melting the bio-based polymer material to obtain a molten body;

[0017] S2, stirring and mixing the melt and the plasticizer to obtain a mixed material A;

[0018] S3, adding a composite flame retardant and a stabilizer to the mixed material A, and continuing to stir and mix to obtain a mixed material B;

[0019] S4, adding filler to the mixed material B, and continuing stirring to obtain a mixed material C;

[0020] S5, preparing the mixed material C into a film by extrusion molding or casting to obtain a bio-based flame retardant decorative film blank;

[0021] S6. Annealing the bio-based flame retardant decorative film blank to eliminate internal stress, and then cooling and cutting to obtain the bio-based flame retardant decorative film.

[0022] Furthermore, a method for preparing a bio-based flame-retardant decorative film: the extrusion molding pressure in step S5 is 10.0 to 20.0 MPa.

[0023] Furthermore, a method for preparing a bio-based flame retardant decorative film: the annealing temperature in step S6 is 40-60°C.

[0024] Specifically, the present invention aims to solve the problems of existing bio-based flame-retardant decorative films in terms of the balance between flame retardant effect and mechanical properties, cost control and process complexity. The bio-based flame-retardant decorative film of the present invention adopts the composite technology of bio-based polymer materials and new environmentally friendly flame retardants, and achieves the improvement of flame retardant effect and the reduction of cost by optimizing the formula and process flow, while ensuring the good mechanical properties of the decorative film.

[0025] Beneficial effects of the present invention:

[0026] (1) The bio-based flame-retardant decorative film of the present invention is compounded with a bio-based polymer material and a compounded flame retardant, which not only effectively improves the flame retardant effect of the decorative film, but also maintains the mechanical properties of the decorative film. At the same time, the present invention also reduces the production cost and simplifies the preparation process by optimizing the formula and process of the decorative film. The decorative film prepared by the present invention has good biodegradability and environmental friendliness, and the preparation process is simple and easy to achieve industrial production. The final product not only has excellent flame retardant properties, but also has good decorative effects, meeting the market demand for high-performance environmentally friendly materials. That is, the bio-based flame-retardant decorative film of the present invention not only achieves an improvement in flame retardant effects, but also maintains good mechanical properties and decorative effects, and the preparation process is simple, the cost is low, and it has good market application prospects.

[0027] (2) The present invention uses a preferred first flame retardant and a second flame retardant to compositely modify the bio-based polymer material, which can significantly enhance the flame retardant effect of the final decorative film:

[0028] Specifically, the preferred first flame retardant of the present invention contains a phosphate group, which can release phosphoric acid during pyrolysis to form a carbon layer, isolate oxygen and heat, and thus improve the flame retardant properties of the decorative film material; at the same time, the preferred second flame retardant is a silicon-containing flame retardant, which can promote the formation of the carbon layer, and the silicate layer formed by silicon at high temperature has good heat insulation and oxygen isolation effects, further improving the flame retardant properties, and the interaction between the second flame retardant and the bio-based polymer material at high temperature will cause the silicon part in the second flame retardant to migrate to the surface of the polymer, thereby enhancing the barrier effect of the surface layer, and the pyrolysis and hydrolysis products of the bio-based polymer material will interact with the phosphorus-oxygen bond and silicon-oxygen bond in the second flame retardant, promote the occurrence of cross-linking reactions, and generate a cross-linked network containing phosphorus and silicon, which helps to form a stable carbonized layer, thereby improving the flame retardant properties of the decorative film. At the same time, the compounding of the first flame retardant and the second flame retardant can form a synergistic effect in the bio-based polymer material, so that the flame retardant properties are better than the effect when used alone, and achieve the outstanding effect of "1+1>2".

[0029] (3) The present invention uses a preferred first flame retardant and a second flame retardant to compositely modify the bio-based polymer material, which can improve the thermal stability of the final decorative film:

[0030] Specifically, the phosphoric acid released by the first flame retardant during the pyrolysis process can act as an acid catalyst to promote the formation of a carbon layer, thereby improving the thermal stability of the decorative film material; at the same time, the silicate layer formed by the second flame retardant under high temperature conditions can also protect the decorative film material from the effects of pyrolysis and oxidation, further improving the thermal stability of the material, thereby making the decorative film less likely to degrade in a high temperature environment and having good thermal stability.

[0031] (4) The present invention uses a preferred first flame retardant and a second flame retardant to compositely modify the bio-based polymer material, which can not only improve the mechanical properties (including tensile strength and elongation at break) of the resulting decorative film, but also enhance the stability of the carbon layer. Through the combined action of the two flame retardants, the formed carbon layer can be made more stable and uniform, thereby more effectively protecting the interior of the decorative film material from direct contact with the flame.

[0032] (5) The present invention uses a preferred first flame retardant and a second flame retardant to composite and modify the bio-based polymer material, which can improve the weather resistance of the resulting decorative film material and improve the fluidity of the bio-based polymer material during processing (i.e., improve the processing performance), thereby reducing the processing difficulty.

[0033] (6) The first flame retardant and the second flame retardant of the present invention are environmentally friendly flame retardants, which can reduce the impact on the environment compared to traditional halogen flame retardants. At the same time, the bio-based polymer material itself is a bio-based material, and the first flame retardant and the second flame retardant used in combination with it are also relatively environmentally friendly, which makes the final decorative film maintain good ecological characteristics while improving the flame retardant performance and is environmentally friendly. At the same time, the preferred composite flame retardant system of the present invention can also reduce the dripping phenomenon when the material is burned and reduce the amount of smoke released. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment 1 provides a bio-based flame retardant decorative film, which includes the following components by mass fraction: 67.6% bio-based polymer material, 13.5% composite flame retardant, 6.8% plasticizer, 1.3% stabilizer and 10.8% filler;

[0037] Wherein, the bio-based polymer material is polylactic acid (PLA), the plasticizer is epoxidized soybean oil, the stabilizer is sorbitol hexaacetate, and the filler is nano-silicon dioxide;

[0038] Among them, the composite flame retardant is compounded by a first flame retardant and a second flame retardant, the first flame retardant is a new type of nitrogen-phosphorus flame retardant, specifically melamine aminotrimethylene phosphate (MATMP); the second flame retardant is a flame retardant containing silicon and caged bicyclic phosphate, specifically tris(2,6,7-trioxa-1-phosphoric acid bicyclo[2.2.2]octane-1-oxygen-4-hydroxymethyl)phenylsilane (TPPSi); the mass ratio of the first flame retardant to the second flame retardant is 7:3.

[0039] The preparation method of the bio-based flame-retardant decorative film of the above-mentioned embodiment 1, the raw materials of the bio-based flame-retardant decorative film include 500.0g of polylactic acid (PLA), 100.0g of composite flame retardant, 50.0g of plasticizer, 10.0g of stabilizer and 80.0g of filler, and the preparation method includes the following steps:

[0040] S1. Preheat 500.0 g of polylactic acid (PLA) at 80° C. to melt to form a uniform melt;

[0041] S2, stirring and mixing the above melt and 50.0 g of plasticizer at 72° C. for 10 minutes to ensure that the plasticizer is evenly dispersed, thereby obtaining a mixed material A;

[0042] S3, adding 100.0 g of the composite flame retardant and 10.0 g of the stabilizer to the above-mentioned mixed material A, and continuing to stir and mix for 15 minutes to fully disperse the flame retardant and the stabilizer to obtain a mixed material B;

[0043] S4, adding 80.0 g of filler to the above-mentioned mixed material B, and continuing to stir at 62° C. until the filler is completely wetted and the mixing system is uniform, to obtain a mixed material C;

[0044] S5, extruding the above-mentioned mixed material C through an extruder (the extrusion pressure is controlled to be 15.0 MPa) to obtain a bio-based flame retardant decorative film blank;

[0045] S6. Annealing the above-mentioned bio-based flame retardant decorative film blank at 50° C. to eliminate internal stress and improve the mechanical properties of the decorative film, and then cooling it through a cooling roller at a temperature of 25° C. and cutting it to obtain the final bio-based flame retardant decorative film.

[0046] Example 2

[0047] This embodiment 2 provides a bio-based flame-retardant decorative film, which includes the following components by mass fraction: 60.0% bio-based polymer material, 20.0% composite flame retardant, 3.0% plasticizer, 2.0% stabilizer and 15.0% filler;

[0048] Wherein, the bio-based polymer material is polybutylene succinate (PBS), the plasticizer is dioctyl sebacate, the stabilizer is rosemary antioxidant, and the filler is talcum powder;

[0049] Among them, the composite flame retardant is compounded by a first flame retardant and a second flame retardant, the first flame retardant is a new type of nitrogen-phosphorus flame retardant, specifically melamine aminotrimethylene phosphate (MATMP); the second flame retardant is a flame retardant containing silicon and caged bicyclic phosphate, specifically tris(2,6,7-trioxa-1-phosphoric acid bicyclo[2.2.2]octane-1-oxygen-4-hydroxymethyl)phenylsilane (TPPSi); the mass ratio of the first flame retardant to the second flame retardant is 6:4.

[0050] The method for preparing the bio-based flame-retardant decorative film of the above-mentioned embodiment 2 comprises the following steps:

[0051] S1. Preheating polybutylene succinate (PBS) to melt and form a uniform melt;

[0052] S2, stirring and mixing the above melt and the plasticizer at 70° C. for 8 minutes to ensure that the plasticizer is evenly dispersed, thereby obtaining a mixed material A;

[0053] S3, adding the composite flame retardant and stabilizer to the above-mentioned mixed material A, and continuing to stir and mix for 10 minutes to fully disperse the flame retardant and stabilizer to obtain a mixed material B;

[0054] S4, adding filler to the above-mentioned mixed material B, and continuing stirring at 60° C. until the filler is completely wetted and the mixing system is uniform, to obtain mixed material C;

[0055] S5, extruding the above-mentioned mixed material C through an extruder (the extrusion pressure is controlled to be 10.0 MPa) to obtain a bio-based flame retardant decorative film blank;

[0056] S6. Annealing the above-mentioned bio-based flame-retardant decorative film blank at 45° C. to eliminate internal stress and improve the mechanical properties of the decorative film, and then cooling it through a cooling roller at a temperature of 20° C. and cutting it to obtain the final bio-based flame-retardant decorative film.

[0057] Example 3

[0058] This embodiment 3 provides a bio-based flame retardant decorative film, which includes the following components by mass fraction: 80.0% bio-based polymer material, 10.0% composite flame retardant, 4.0% plasticizer, 1.0% stabilizer and 5.0% filler;

[0059] Wherein, the bio-based polymer material is polylactic acid, the plasticizer is epoxy oleate, the stabilizer is grape seed extract, and the filler is glass fiber;

[0060] Among them, the composite flame retardant is compounded by a first flame retardant and a second flame retardant, the first flame retardant is a new type of nitrogen-phosphorus flame retardant, specifically melamine aminotrimethylene phosphate (MATMP); the second flame retardant is a flame retardant containing silicon and caged bicyclic phosphate, specifically tris(2,6,7-trioxa-1-phosphoric acid bicyclo[2.2.2]octane-1-oxygen-4-hydroxymethyl)phenylsilane (TPPSi); the mass ratio of the first flame retardant to the second flame retardant is 8:2.

[0061] The method for preparing the bio-based flame-retardant decorative film of the above-mentioned embodiment 3 comprises the following steps:

[0062] S1, preheating and melting polylactic acid (PLA) to form a uniform melt;

[0063] S2, stirring and mixing the above melt and the plasticizer at 75° C. for 12 minutes to ensure that the plasticizer is evenly dispersed, thereby obtaining a mixed material A;

[0064] S3, adding the composite flame retardant and stabilizer to the above-mentioned mixed material A, and continuing to stir and mix for 20 minutes to fully disperse the flame retardant and stabilizer to obtain a mixed material B;

[0065] S4, adding filler to the above-mentioned mixed material B, and continuing stirring at 65° C. until the filler is completely wetted and the mixing system is uniform, to obtain mixed material C;

[0066] S5, extruding the mixture C through an extruder (the extrusion pressure is controlled to be 20.0 MPa) to obtain a bio-based flame retardant decorative film blank;

[0067] S6. The above-mentioned bio-based flame retardant decorative film blank is annealed at 55° C. to eliminate internal stress and improve the mechanical properties of the decorative film, and then cooled by a cooling roller at a temperature of 20° C. and cut to obtain the final bio-based flame retardant decorative film.

[0068] Comparative Example 1

[0069] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, no flame retardant is added to modify the polylactic acid, and the other conditions are the same as those in Example 1.

[0070] Comparative Example 2

[0071] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, polylactic acid is modified by only a single first flame retardant (melamine aminotrimethylene phosphate (MATMP), and the other conditions are the same as those in Example 1.

[0072] Comparative Example 3

[0073] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, polylactic acid is modified only by a single second flame retardant (tris(2,6,7-trioxa-1-phosphobicyclo[2.2.2]octane-1-oxy-4-hydroxymethyl)phenylsilane (TPPSi)), and the rest is the same as Example 1.

[0074] Comparative Example 4

[0075] Provided is a bio-based flame-retardant decorative film, the decorative film comprising the following components by mass fraction: 67.6% of a bio-based polymer material, 13.5% of a composite flame retardant, 6.8% of a plasticizer, 1.3% of a stabilizer, and 10.8% of a filler;

[0076] Wherein, the bio-based polymer material is polylactic acid (PLA), the plasticizer is epoxidized soybean oil, the stabilizer is sorbitol hexaacetate, and the filler is nano-silicon dioxide;

[0077] The composite flame retardant is compounded by flame retardant A and flame retardant B, the flame retardant A is ammonium polyphosphate (APP), the flame retardant B is chitosan (CS), and the mass ratio of the flame retardant A to the flame retardant B is 7:3.

[0078] The difference between the comparative example 4 and the embodiment 1 is that the flame retardant in the comparative example 4 is different from that in the embodiment 1, and the other conditions are the same. The flame retardant in the comparative example 4 is a currently existing flame retardant system.

[0079] test:

[0080] (1) The oxygen index of the bio-based flame-retardant decorative film obtained in Example 1 and Comparative Examples 1 to 4 and the pure polylactic acid material was tested. The results showed that:

[0081] ① The limiting oxygen index LOI value of the bio-based flame retardant decorative film obtained in Example 1 is 33.2%, while the limiting oxygen index LOI value of the decorative film in Comparative Example 1 is 18.6%. It can be seen that after the polylactic acid is composite-modified by the first flame retardant and the second flame retardant in Example 1, the flame retardant properties of the flame retardant decorative film obtained are greatly improved;

[0082] ② The limiting oxygen index LOI value of the bio-based flame retardant decorative film obtained in Comparative Example 2 is 24.8%, while the limiting oxygen index LOI value of the decorative film in Comparative Example 1 is 18.6%. It can be seen that Comparative Example 2 uses a single flame retardant (MATMP) to modify the polylactic acid, and the improvement of the flame retardant properties of the obtained decorative film is obviously not as good as the composite flame retardant of the present application;

[0083] ③ The limiting oxygen index LOI value of the bio-based flame retardant decorative film obtained in Comparative Example 3 is 25.3%, while the limiting oxygen index LOI value of the decorative film in Comparative Example 1 is 18.6%. It can be seen that Comparative Example 3 uses a single flame retardant (TPPSi) to modify polylactic acid, and its improvement in the flame retardant properties of the obtained decorative film is obviously not as good as the composite flame retardant of the present application;

[0084] ④ The limiting oxygen index LOI value of the bio-based flame retardant decorative film obtained in Comparative Example 4 is 30.1%, while the limiting oxygen index LOI value of the decorative film in Comparative Example 1 is 18.6%. It can be seen that Comparative Example 4 uses the existing flame retardant system (APP and CS) to modify polylactic acid, and its improvement in the flame retardant properties of the obtained decorative film is obviously not as good as the composite flame retardant of the present application.

[0085] In summary, it can be seen that the composite flame retardant preferably compounded in the present application can significantly improve the flame retardant properties of the decorative film, and the present application can form a synergistic effect in the polylactic acid matrix by compounding MATMP and TPPSi, so that the flame retardant properties of the final decorative film are better than those when used alone, achieving the excellent effect of "1+1>2".

[0086] (2) UL-94 vertical burning test: Through the UL-94 vertical burning test, it was found that the UL-94 grade of the decorative film obtained in Example 1 was V-0, while the UL-94 grade of the comparative example 1 was V-2. The present invention uses a composite flame retardant to compositely modify polylactic acid, thereby raising the UL-94 grade from V-2 to V-0, and the flame retardant performance is greatly improved.

[0087] (3) Thermal stability test: After thermogravimetric analysis (TGA), it was found that the thermal decomposition temperature of the decorative film obtained in Example 1 was 234°C, while the thermal decomposition temperature of the comparative example 1 (not modified with flame retardant) was 218°C. It can be seen that the present invention significantly improves the thermal decomposition temperature of the decorative film by preferably compounding the composite modifier, thereby improving the thermal stability.

[0088] (4) Mechanical properties test: After testing with a universal tensile testing machine, it was found that: ① The tensile strength of the decorative film obtained in Example 1 was about 52.67 MPa, and the tensile strength of the decorative film obtained in Comparative Example 1 was about 41.38 MPa; the elongation at break of the decorative film in Example 1 was about 137.22%, and the elongation at break of the decorative film in Comparative Example 1 was about 100.84%; it can be seen that the preferred composite flame retardant of the present application can significantly improve the mechanical properties of the resulting decorative film; ② The tensile strength of the decorative film obtained in Comparative Example 4 was about 46.59 MPa, and the elongation at break was about 133.83%. It can be seen that the tensile strength of the decorative film obtained by the existing flame retardant system used in Comparative Example 4 was reduced by about 11.53% and the elongation at break was reduced by about 2.47% compared with those in Example 1. Therefore, the decorative film of Example 1 is significantly better than that of Comparative Example 4 in terms of mechanical properties. It can be said that the preferred composite flame retardant of the present application can significantly improve the mechanical properties of the decorative film.

[0089] (5) Weathering test: After UV accelerated aging test, it was found that:

[0090] ① The tensile strength of the decorative film obtained in Example 1 is about 38.69 MPa, and the elongation at break is about 102.91%. It can be seen that compared with before the aging test, the tensile strength retention rate of the decorative film in Example 1 is about 73.45%, and the elongation at break retention rate is about 74.99%;

[0091] ② The tensile strength of the decorative film obtained in Comparative Example 1 is about 21.83 MPa, and the elongation at break is about 53.80%. It can be seen that compared with before the aging test, the tensile strength retention rate of the decorative film in Comparative Example 1 is about 52.76%, and the elongation at break retention rate is about 53.35%;

[0092] ③ The tensile strength of the decorative film obtained in Comparative Example 4 is about 27.04 MPa, and the elongation at break is about 76.75%. It can be seen that compared with before the aging test, the tensile strength retention rate of the decorative film in Comparative Example 4 is about 58.04%, and the elongation at break retention rate is about 57.35%.

[0093] In summary, it can be seen that the tensile strength retention rate of the existing composite flame retardant system used in Comparative Example 4 is reduced by about 20.98% and the elongation at break is reduced by about 23.52% compared with the MTAMP and TPPSi systems in the present application. Therefore, the decorative film of the present application has better weather resistance.

[0094] The above are preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A bio-based flame retardant decorative film, characterized in that: The decorative film comprises the following components by mass fraction: 60.0-80.0% of bio-based polymer material, 10.0-30.0% of composite flame retardant, 2.0-10.0% of plasticizer, 0.5-2.0% of stabilizer and 5.0-15.0% of filler; The composite flame retardant is compounded by a first flame retardant and a second flame retardant. The first flame retardant is a novel nitrogen-phosphorus flame retardant, and the second flame retardant is a flame retardant containing silicon and caged bicyclic phosphate groups.

2. The bio-based flame-retardant decorative film according to claim 1, characterized in that: The bio-based polymer material is polylactic acid or polybutylene succinate.

3. The bio-based flame-retardant decorative film according to claim 1, characterized in that: The first flame retardant is melamine aminotrimethylene phosphate.

4. The bio-based flame-retardant decorative film according to claim 1, characterized in that: The second flame retardant is tris(2,6,7-trioxa-1-phosphoric acid bicyclo[2.2.2]octane-1-oxygen-4-hydroxymethyl)phenylsilane.

5. A bio-based flame retardant decorative film according to claim 1, 3 or 4, characterized in that: The first flame retardant in the composite flame retardant accounts for 60.0-80.0 wt %.

6. The bio-based flame retardant decorative film according to claim 5, characterized in that: The first flame retardant accounts for 70.0 wt % of the composite flame retardant.

7. The bio-based flame-retardant decorative film according to claim 1, characterized in that: The plasticizer is selected from at least one of epoxidized soybean oil, epoxidized oleic acid ester, dibutyl sebacate, and dioctyl sebacate; The stabilizer is selected from at least one of sorbitol hexaacetate, epigallocatechin gallate, rosemary antioxidant, rosemary extract, grape seed extract, and green tea extract; The filler is selected from at least one of talc powder, mica powder, nano silicon dioxide, nano montmorillonite, wood powder, rice husk powder, graphene and glass fiber.

8. The method for preparing a bio-based flame-retardant decorative film according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1, preheating and melting the bio-based polymer material to obtain a molten body; S2, stirring and mixing the melt and the plasticizer to obtain a mixed material A; S3, adding a composite flame retardant and a stabilizer to the mixed material A, and continuing to stir and mix to obtain a mixed material B; S4, adding filler to the mixed material B, and continuing stirring to obtain a mixed material C; S5, preparing the mixed material C into a film by extrusion molding or casting to obtain a bio-based flame retardant decorative film blank; S6. Annealing the bio-based flame retardant decorative film blank to eliminate internal stress, and then cooling and cutting to obtain the bio-based flame retardant decorative film.

9. The method for preparing a bio-based flame-retardant decorative film according to claim 7, characterized in that: The pressure of the extrusion molding in step S5 is 10.0 to 20.0 MPa.

10. The method for preparing a bio-based flame-retardant decorative film according to claim 7, characterized in that: The annealing temperature in step S6 is 40-60°C.