Polyurethane outer packaging material with synergistic flame retardance of molybdenum trioxide, ammonium polyphosphate and organosilsesquioxane and preparation method

Abstract

The invention discloses a polyurethane outer packaging material with synergistic flame retardance of molybdenum trioxide, ammonium polyphosphate and organosilsesquioxane and a preparation method of the polyurethane outer packaging material, and belongs to the field of development of flame-retardant materials. The flame-retardant polyurethane flexible foam is synthesized through a one-step foaming process, the obtained flame-retardant polyurethane flexible foam material has an extremely good flame-retardant effect, and flame-retardant indexes such as limit oxygen index, thermal stability, heat release rate, total heat release, smoke yield, total smoke yield and carbon residue of the flame-retardant polyurethane flexible foam material are greatly improved; through the synergistic flame-retardant effect of molybdenum trioxide, ammonium polyphosphate and organosilsesquioxane, the polyurethane outer packaging material with an extremely prominent flame-retardant effect is developed, and the polyurethane outer packaging material has an extremely good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardant material development, and in particular to a polyurethane outer packaging material with coordinated flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane and a preparation method thereof. Background Art

[0002] Due to the flammability of polyurethane soft foam, flame retardant treatment is required to inhibit its combustion or reduce the burning speed. When a fire occurs, the toxic gases and particulate matter in the smoke generated by the combustion are often more deadly than the fire and heat in the fire. Therefore, the development of an efficient, halogen-free, low-smoke and low-toxic flame retardant FPUF is the key to expanding the application field of FPUF. Ammonium polyphosphate (APP) is widely used as an efficient and non-toxic inorganic phosphorus flame retardant. Jiang Haohao et al. prepared polyurethane foam with APP as a flame retardant. After flame retardation, the LOI of the foam reached 23.6%, and the vertical combustion reached the UL94 V-0 level. Jiang Changchen et al. used AlPO4 and APP as flame retardants and added them to polyurethane soft foam. The addition of AlPO4 and APP formed a carbon layer on the surface of the foam, which effectively played the role of flame retardant combustibles. Xue Jianying et al. used the synergistic flame retardant effect of APP and Mg(OH)2 to enhance the flame retardancy of polyurethane foam. Li et al. used β-cyclodextrin modified APP as a flame retardant. The flame spread rate of polyurethane soft foam was reduced by 67.3% compared with pure foam, the extinguishing time was reduced by 2.1s, and the peak heat release rate of flame retardant foam was reduced by 43.8%. Molybdenum trioxide (MoO3) is more remarkable for its smoke suppression performance. Ma Yufeng et al. used APP, C5H 12 O4, MoO3 and other three substances synergistically flame retardant, enhance the flame retardancy of phenolic foam, and found that the oxygen index of flame retardant phenolic foam increased by about 73%. Liu Xiu et al. studied the smoke suppression effect of MoO3 on expandable EG and APP composite flame retardant polyurethane foam plastics, and found that MoO3 has good flame retardant and smoke suppression effects, and also improves the thermal stability of the foam. Hu Boyuan et al. studied the effects of cuprous oxide and MoO3 on the oxygen index, smoke density, heat release rate and residual carbon rate of flame retardant polyurethane foam, and found that MoO3 flame retardant polyurethane foam has less smoke and higher residual carbon rate.

[0003] The invention uses APP, MoO3 and POSS as composite synergistic flame retardants and adopts a one-step foaming synthesis method to prepare flame-retardant FPUF. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art, provide a polyurethane outer packaging material and a preparation method for the synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane, and belong to the field of flame retardant material development. The present invention adds molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane to a polyurethane soft foam system for synergistic flame retardancy, and synthesizes the flame retardant polyurethane soft foam through a one-step foaming process. The obtained flame retardant polyurethane soft foam material has an extremely good flame retardant effect, and its limiting oxygen index, thermal stability, heat release rate and total heat release, smoke production rate and total smoke production, carbon residue and other flame retardant indicators are greatly improved. Through the synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane, a polyurethane outer packaging material with extremely outstanding flame retardant effect is developed, which has excellent application prospects.

[0005] In order to achieve the above technical effects, the following technical solutions are adopted:

[0006] A method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane, comprising the following steps:

[0007] Step S1: sequentially add polyether polyol PPO, stannous isooctanoate, triethylenediamine A33, silicone oil L580, deionized water, ammonium polyphosphate APP, molybdenum trioxide MoO3 and organosilsesquioxane POSS into a reaction container, and stir and mix them evenly with a stirrer to obtain a mixed solution;

[0008] Step S2: Add toluene diisocyanate TDI-80 into another reaction container, and quickly add the mixed solution obtained in step S1 into toluene diisocyanate TDI-80, and stir to mix evenly; after the foaming reaction is carried out for a certain period of time, transfer the mixture to a mold to allow it to foam naturally; after the foam is stabilized, let the foam stand to obtain polyurethane soft foam, which is the polyurethane outer packaging material.

[0009] Furthermore, in step S1, the molecular weight of the polyether polyol PPO is 3000-4000.

[0010] Furthermore, in step S1, the mass ratio of polyether polyol PPO, stannous isooctanoate, triethylenediamine A33, silicone oil L580, deionized water and toluene diisocyanate TDI-80 is 30-40: 0.1-0.15: 0.1-0.15: 0.1-0.15: 3-5: 15-20.

[0011] Furthermore, in step S1, the total mass of ammonium polyphosphate APP, molybdenum trioxide MoO3 and organosilsesquioxane POSS accounts for 14%-16% of the total mass of polyether polyol PPO, stannous isooctanoate, triethylenediamine A33, silicone oil L580, deionized water and toluene diisocyanate TDI-80.

[0012] Furthermore, in the step S1, the mass ratio of ammonium polyphosphate APP, molybdenum trioxide MoO3 and organosilsesquioxane POSS is 13-28:14-26:3-6.

[0013] Furthermore, in step S2, after the foaming reaction is carried out for 10-15 seconds, the mixture is transferred to a mold to allow it to foam naturally.

[0014] Furthermore, in step S2, the foam standing temperature is 25°C-40°C.

[0015] Furthermore, the foam is allowed to stand for 24-48 hours.

[0016] A polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane, prepared by any of the above preparation methods.

[0017] A polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane is used in the field of flame retardancy of lithium battery outer packaging.

[0018] The beneficial effects of the present invention are:

[0019] The invention discloses a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane and a preparation method thereof, belonging to the field of flame retardant material development. The invention adds molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane into a polyurethane soft foam system for synergistic flame retardancy, and synthesizes the flame retardant polyurethane soft foam through a one-step foaming process. The obtained flame retardant polyurethane soft foam material has extremely good flame retardancy, and its limiting oxygen index, thermal stability, heat release rate and total heat release, smoke production rate and total smoke production, carbon residue and other flame retardancy indicators are greatly improved. Through the synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane, a polyurethane outer packaging material with extremely outstanding flame retardancy is developed, which has excellent application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a limiting oxygen index curve of the polyurethane soft foam FPUF material in an embodiment of the present invention;

[0021] Figure 2 This is the heat release rate curve of the polyurethane soft foam FPUF material in the embodiment of the present invention;

[0022] Figure 3 This is the total heat release curve of the polyurethane soft foam FPUF material in the embodiment of the present invention;

[0023] Figure 4 This is the smoke generation rate curve of the polyurethane soft foam FPUF material in the embodiment of the present invention;

[0024] Figure 5 is the total smoke production curve of the polyurethane soft foam FPUF material in the embodiment of the present invention;

[0025] Figure 6 This is a digital photo of the carbon residue remaining after the polyurethane soft foam FPUF material in the embodiment of the present invention is burned in the atmosphere of a cone calorimeter. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings, and the protection scope of the present invention is not limited to the following:

[0027] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0028] The experimental raw materials for preparing polyurethane soft foam FPUF include: polyether polyol (PPO), triethylene diamine (A33), stannous isooctanoate, silicone oil (L580), deionized water and toluene diisocyanate (TDI-80). The specifications and manufacturer information of the experimental raw materials are shown in Table 1:

[0029] Table 1 Experimental raw materials

[0030]

[0031] The production specifications and manufacturers of the flame retardants used are: ammonium polyphosphate APP (TY-1324), Shandong Yousuo Chemical Technology Co., Ltd.; molybdenum trioxide, Shandong Yousuo Chemical Technology Co., Ltd.; organic silsesquioxane POSS: industrial grade, structural benzene content of 41% to 49%, structural silicon content of 33% to 44%, BASF, Germany.

[0032] Embodiment 1:

[0033] The preparation method is:

[0034] (1) 30 g of polyether polyol PPO, 0.1 g of stannous isooctanoate, 0.1 g of triethylenediamine A33, 0.15 g of silicone oil L580, 3 parts of deionized water, 4.48 g of ammonium polyphosphate APP, 2.24 g of molybdenum trioxide MoO3 and 0.48 g of organosilicon sesquioxane POSS were added to a beaker in sequence, and stirred with an electric stirrer to mix them evenly.

[0035] (2) Add 15 g of TDI to another beaker and quickly add it to the above mixed solution, stirring to mix it evenly. After the foaming reaction is carried out for 10 seconds, transfer the mixture to a mold to allow it to foam naturally. After the foam is stable, place the foam at 25°C-40°C for 24 hours to obtain polyurethane soft foam FPUF-A, referred to as polyurethane soft foam A.

[0036] Embodiment 2:

[0037] The preparation method is:

[0038] (1) 30 g of polyether polyol PPO, 0.1 g of stannous isooctanoate, 0.1 g of triethylenediamine A33, 0.15 g of silicone oil L580, 3 parts of deionized water, 2.08 g of ammonium polyphosphate APP, 4.16 g of molybdenum trioxide MoO3 and 0.96 g of organosilicon sesquioxane POSS were added to a beaker in sequence, and stirred with an electric stirrer to mix them evenly.

[0039] (2) Add 15 g of TDI to another beaker and quickly add it to the above mixed solution, stirring to mix it evenly. After the foaming reaction is carried out for 10 seconds, transfer the mixture to a mold to allow it to foam naturally. After the foam is stable, place the foam at 25°C-40°C for 24 hours to obtain polyurethane soft foam FPUF-B, referred to as polyurethane soft foam B.

[0040] Comparative Example 1:

[0041] Taking Example 1 as a benchmark, the preparation method of Comparative Example 1 is exactly the same as that of Example 1, with the only difference being that 4.48 g of ammonium polyphosphate APP, 2.24 g of molybdenum trioxide MoO3 and 0.48 g of organic silsesquioxane POSS in Example 1 are all removed, and the other preparation methods are exactly the same as those in the example to obtain polyurethane soft foam FPUF-C, referred to as polyurethane soft foam C.

[0042] Comparative Example 2:

[0043] Taking Example 1 as a benchmark, the preparation method of Comparative Example 1 is exactly the same as that of Example 1, with the only difference being that the flame retardant formula in Example 1: 4.48 g of ammonium polyphosphate APP, 2.24 g of molybdenum trioxide MoO3 and 0.48 g of organic silsesquioxane POSS are replaced with: 6.72 g of ammonium polyphosphate APP and 0.48 g of organic silsesquioxane POSS, and the other preparation methods are exactly the same as those in the example to obtain polyurethane soft foam FPUF-D, referred to as polyurethane soft foam D.

[0044] Comparative Example 3:

[0045] Taking Example 1 as a benchmark, the preparation method of Comparative Example 1 is exactly the same as that of Example 1, with the only difference being that the flame retardant formula in Example 1: 4.48 g of ammonium polyphosphate APP, 2.24 g of molybdenum trioxide MoO3 and 0.48 g of organic silsesquioxane POSS are replaced with: 6.72 g of molybdenum trioxide MoO3 and 0.48 g of organic silsesquioxane POSS, and the other preparation methods are exactly the same as those in the example to obtain polyurethane soft foam FPUF-E, referred to as polyurethane soft foam E.

[0046] Comparative Example 4:

[0047] Taking Example 1 as a benchmark, the preparation method of Comparative Example 1 is exactly the same as that of Example 1, with the only difference being that the flame retardant formula in Example 1: 4.48 g of ammonium polyphosphate APP, 2.24 g of molybdenum trioxide MoO3 and 0.48 g of organic silsesquioxane POSS are replaced with: 4.48 g of ammonium polyphosphate APP, 2.72 g of molybdenum trioxide MoO3, and the other preparation methods are exactly the same as those in the example to obtain polyurethane soft foam FPUF-F, referred to as polyurethane soft foam F.

[0048] Comparative Example 5:

[0049] Taking Example 1 as a benchmark, the preparation method of Comparative Example 1 is exactly the same as that of Example 1, with the only difference being that the flame retardant formula in Example 1: 4.48 g of ammonium polyphosphate APP, 2.24 g of molybdenum trioxide MoO3 and 0.48 g of organic silsesquioxane POSS are replaced with 7.20 g of ammonium polyphosphate APP, and the other preparation methods are exactly the same as those in the example to obtain polyurethane soft foam FPUF-G, referred to as polyurethane soft foam G.

[0050] Comparative Example 6:

[0051] Taking Example 1 as a benchmark, the preparation method of Comparative Example 1 is exactly the same as that of Example 1, with the only difference being that the flame retardant formula in Example 1: 4.48 g of ammonium polyphosphate APP, 2.24 g of molybdenum trioxide MoO3 and 0.48 g of organic silsesquioxane POSS are replaced with 7.20 g of molybdenum trioxide MoO3, and the other preparation methods are exactly the same as those in the example to obtain polyurethane soft foam FPUF-H, referred to as polyurethane soft foam H.

[0052] Comparative Example 7:

[0053] Taking Example 1 as a benchmark, the preparation method of Comparative Example 1 is exactly the same as that of Example 1, with the only difference being that the flame retardant formula in Example 1: 4.48 g of ammonium polyphosphate APP, 2.24 g of molybdenum trioxide MoO3 and 0.48 g of organic silsesquioxane POSS are replaced with 7.20 g of organic silsesquioxane POSS, and the other preparation methods are exactly the same as those in the example to obtain polyurethane soft foam FPUF-I, referred to as polyurethane soft foam I.

[0054] Based on the polyurethane soft foam FPUF materials prepared in Examples 1-2 and Comparative Examples 1-7, the flame retardant properties thereof were evaluated and characterized:

[0055] Experimental results and analysis:

[0056] 1. Limiting oxygen index (LOI)

[0057] The combustion difficulty of FPUF is observed by conducting a limiting oxygen index (LOI) test on the FPUF sample. A high oxygen index means that the foam is difficult to burn, and a low oxygen index means that the foam is easy to burn.

[0058] like Figure 1 Shown is a limiting oxygen index curve of the polyurethane soft foam FPUF materials (FPUF-A, FPUF-B, FPUF-C, FPUF-D, FPUF-E, FPUF-F, FPUF-G, FPUF-H, FPUF-I) prepared in Examples 1-2 and Comparative Examples 1-7.

[0059] from Figure 1 It can be seen that the oxygen index of the non-flame-retardant polyurethane foam FPUF-C is 17.5%; the oxygen index of the polyurethane foam containing only one flame retardant or two flame retardants is between 19% and 20%, but when the polyurethane foam system contains three flame retardants, its oxygen index rises sharply to about 40%, which has an extremely good flame retardant effect. The three flame retardants work synergistically in the polyurethane soft foam material and enhance their effectiveness together, achieving an excellent flame retardant effect.

[0060] 2. Thermal stability

[0061] Thermogravimetric analyzer can be used to observe the relationship between the mass of FPUF samples and temperature, and to study and analyze the thermal stability of FPUF;

[0062] As shown in Table 2, Table 2 is the pyrolysis parameters obtained from the TG curve and DTG curve of the FPUF sample, where T -5％ is the starting thermal decomposition temperature, T max1 , T max2 is the maximum thermal weight loss temperature.

[0063] As can be seen from Table 2, all FPUFs have two weight loss stages. The first weight loss stage is the breakage of polyurethane bonds leading to the release of isocyanate and polyols, and the second weight loss stage is the degradation and release of polyether oligomers and refractory polyols remaining in the foam; the initial thermal decomposition temperature of the non-flame retardant polyurethane soft foam FPUF-C is 252°C, the maximum thermal weight loss temperature in the first weight loss stage is 276°C; the maximum thermal weight loss temperature in the second weight loss stage is 363°C; the residual carbon content is only 0.55%, and the flame retardant parameters of polyurethane foams containing only one flame retardant or two flame retardants are improved, but not very obvious. However, when the polyurethane foam system contains three flame retardants, its flame retardant parameters increase significantly, and it has an extremely good flame retardant effect. The three flame retardants work synergistically in the polyurethane soft foam material and enhance the effect together, which has an excellent flame retardant effect.

[0064] Table 2 Pyrolysis parameters of polyurethane soft foam FPUF

[0065]

[0066] 3. Heat release rate and total heat release

[0067] The flame retardant performance parameters of polyurethane foam can be analyzed using a cone calorimeter. Cone calorimeter is a standard method for testing the combustion performance of polymer materials. It can simulate the combustion of materials under real fire conditions and effectively analyze the flame retardant performance of the tested polymer materials.

[0068] like Figure 2 and Figure 3 As shown, the heat release rate and total heat release curves of the polyurethane soft foam FPUF materials (FPUF-A, FPUF-B, FPUF-C, FPUF-D, FPUF-E, FPUF-F, FPUF-G, FPUF-H, FPUF-I) prepared in Examples 1-2 and Comparative Examples 1-7 are shown in Table 3. Figure 2 and Figure 3 The cone calorimetry parameters (pkHRR and THR) were obtained. Figure 2 and Figure 3 It can be seen that the non-flame retardant polyurethane soft foam FPUF-C not only has the highest pkHRR (480.41kW / m 2 ), THR is the highest (27.20MJ / m 2 ), the fire hazard is high; the pkHRR and THR of the polyurethane foam containing only one flame retardant in equal amounts or two flame retardants in equal amounts are reduced, but not very obvious. However, when the polyurethane foam system contains three flame retardants, its pkHRR and THR are greatly reduced, and it has an extremely good flame retardant effect. The three flame retardants work synergistically in the polyurethane soft foam material and enhance their effectiveness together, achieving an excellent flame retardant effect.

[0069] Table 3 Cone calorimetry parameters (pkHRR and THR)

[0070]

[0071] 4. Smoke production rate and total smoke production

[0072] It should be noted that in a fire, the real most deadly thing is often the smoke, dust and toxic and harmful gases produced by combustion, rather than flames and heat. Therefore, it is very important to analyze the smoke production rate (SPR) and total smoke production (TSP) of polyurethane soft foam during combustion and reduce the release of smoke particles produced during the combustion process.

[0073] like Figure 4 and Figure 5 As shown in Table 4, the smoke production rate and total smoke production curves of the polyurethane soft foam FPUF materials (FPUF-A, FPUF-B, FPUF-C, FPUF-D, FPUF-E, FPUF-F, FPUF-G, FPUF-H, FPUF-I) prepared in Examples 1-2 and Comparative Examples 1-7 are shown in Table 4. Figure 4 and Figure 5 Cone calorimetry parameters (SPR and TSP) obtained by Figure 4 and Figure 5 It can be seen that the non-flame-retardant FPUF still has the highest peak smoke generation rate (0.071m 2 / s) and total smoke production (3.53m 2 ); The SPR and TSP of the polyurethane foam containing only one flame retardant in equal amounts or two flame retardants in equal amounts are reduced, but not significantly. However, when the polyurethane foam system contains three flame retardants, its SPR and TSP are greatly reduced, and it has an extremely good flame retardant effect. The three flame retardants work synergistically in the polyurethane soft foam material and enhance the effect together, which has an excellent flame retardant effect.

[0074] Table 4 Cone calorimetry parameters (SPR and TSP)

[0075]

[0076] 5. Carbon residue analysis

[0077] Carbon residue is an important basis for analyzing the flame retardant properties of materials. Generally speaking, dense and continuous carbon residue can significantly reduce the fire hazard of polymer materials. Dense carbon residue can also indicate that flame retardant polyurethane soft foam has good flame retardancy, while non-flame retardant FPUF will leave no or little carbon residue after burning.

[0078] like Figure 6As shown, it is a digital photograph of the carbon residue remaining after the polyurethane soft foam FPUF materials (FPUF-A, FPUF-B, FPUF-C, FPUF-D, FPUF-E, FPUF-F, FPUF-G, FPUF-H, FPUF-I) prepared in Examples 1-2 and Comparative Examples 1-7 are burned in the atmosphere of a cone calorimeter; Figure 6 As shown in the figure, the non-flame-retardant polyurethane soft foam FPUF-C has been completely burned due to the lack of flame retardant addition and its own high flammability, leaving almost no carbon residue; the polyurethane foam containing only one flame retardant or two flame retardants has increased carbon residue, but it is not obvious. However, when the polyurethane foam system contains three flame retardants, the carbon residue increases significantly, and it can be observed that the surface of the carbon layer is relatively smooth. This carbon layer plays a role in heat insulation and oxygen isolation, effectively reducing the heat release rate, total heat release and total smoke production during foam combustion. It has an extremely good flame retardant effect. The three flame retardants work synergistically in the polyurethane soft foam material and enhance the effect together, which has an excellent flame retardant effect.

[0079] In summary, the present invention discloses a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane and a preparation method, which belongs to the field of flame retardant material development. The present invention adds molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane to a polyurethane soft foam system for synergistic flame retardancy, and synthesizes a flame retardant polyurethane soft foam through a one-step foaming process. The obtained flame retardant polyurethane soft foam material has extremely good flame retardant effect, and its limiting oxygen index, thermal stability, heat release rate and total heat release, smoke production rate and total smoke production, carbon residue and other flame retardant indicators are greatly improved. Through the synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organic silsesquioxane, a polyurethane outer packaging material with extremely outstanding flame retardant effect is developed, which has excellent application prospects.

[0080] At this point, those skilled in the art recognize that, although the embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the contents disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane, characterized in that: The preparation method comprises the following steps: Step S1: sequentially add polyether polyol PPO, stannous isooctanoate, triethylenediamine A33, silicone oil L580, deionized water, ammonium polyphosphate APP, molybdenum trioxide MoO3 and organosilsesquioxane POSS into a reaction container, and stir and mix them evenly with a stirrer to obtain a mixed solution; Step S2: Add toluene diisocyanate TDI-80 into another reaction container, and quickly add the mixed solution obtained in step S1 into toluene diisocyanate TDI-80, and stir to mix evenly; after the foaming reaction is carried out for a certain period of time, transfer the mixture to a mold to allow it to foam naturally; after the foam is stabilized, let the foam stand to obtain polyurethane soft foam, which is the polyurethane outer packaging material.

2. The method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane as claimed in claim 1, characterized in that: In the step S1, the molecular weight of the polyether polyol PPO is 3000-4000.

3. The method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane as claimed in claim 1, characterized in that: In the step S1, the mass ratio of polyether polyol PPO, stannous isooctanoate, triethylenediamine A33, silicone oil L580, deionized water and toluene diisocyanate TDI-80 is 30-40: 0.1-0.15: 0.1-0.15: 0.1-0.15: 3-5: 15-20.

4. The method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane as claimed in claim 1, characterized in that: In the step S1, the total mass of ammonium polyphosphate APP, molybdenum trioxide MoO3 and organosilsesquioxane POSS accounts for 14%-16% of the total mass of polyether polyol PPO, stannous isooctanoate, triethylenediamine A33, silicone oil L580, deionized water and toluene diisocyanate TDI-80.

5. The method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane as claimed in claim 4, characterized in that: In the step S1, the mass ratio of ammonium polyphosphate APP, molybdenum trioxide MoO3 and organic silsesquioxane POSS is 13-28:14-26:3-6.

6. The method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane as claimed in claim 4, characterized in that: In step S2, after the foaming reaction is carried out for 10-15 seconds, the mixture is transferred to a mold to allow it to foam naturally.

7. The method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane as claimed in claim 4, characterized in that: In the step S2, the foam is left to stand at a temperature of 25°C-40°C.

8. The method for preparing a polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane as claimed in claim 4, characterized in that: In step S2, the foam is left to stand for 24-48 hours.

9. A polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane, characterized in that: The compound is prepared by any one of the preparation methods of claims 1 to 8.

10. The polyurethane outer packaging material with synergistic flame retardancy of molybdenum trioxide, ammonium polyphosphate and organosiliconesquioxane as claimed in claim 9, characterized in that: The polyurethane outer packaging material is used in the field of flame retardancy of lithium battery outer packaging.

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