A highly flame-retardant and degradable bio-based polymer material and its preparation method

Abstract

The present invention belongs to the technical field of polymer materials, and provides a highly flame-retardant and degradable bio-based polymer material and a preparation method thereof. Based on the degradable bio-based material polylactic acid, the present invention realizes the high flame-retardant performance of the material by introducing a bio-based flame retardant. First, L-lactic acid and methacrylic acid are subjected to an esterification reaction under the action of an acidic catalyst to obtain lactate methacrylate, and then reacted with 2-(2-ethoxyethoxy)ethanol to generate an ester compound with a long-chain structure and unsaturated groups. Subsequently, a flame retardant containing a phosphaphenanthrene group is used to carry out an addition reaction with the ester compound to prepare a bio-based flame retardant with a flame-retardant effect, so that the material has a good carbonization effect and the ability to inhibit flame spread during combustion, and polylactic acid, the bio-based flame retardant, an antioxidant, a lubricant, an ultraviolet absorber and a modified compatibilizer are mixed to finally obtain a bio-based polymer material with excellent flame retardancy and degradability.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a highly flame-retardant and degradable bio-based polymer material and a preparation method thereof. Background Art

[0002] Traditional polymer materials, such as polyethylene, polypropylene, polystyrene, etc., are widely used in industrial production, consumer goods manufacturing, and construction due to their excellent mechanical properties, chemical stability, wear resistance, and low cost. These materials have significant advantages in processing performance, durability, and corrosion resistance. However, their environmental impact and insufficient flame retardancy have become increasingly prominent and have attracted widespread attention.

[0003] First, traditional polymer materials are mostly derived from petrochemical raw materials. These materials are difficult to degrade in the natural environment, leading to plastic pollution problems. Secondly, traditional polymer materials generally have the defect of poor flame retardancy. Under high temperature or fire conditions, polymer materials are extremely easy to burn and release a large amount of heat and a large amount of toxic gases, such as carbon monoxide, carbon dioxide and dioxins, which lead to the rapid spread of fire and secondary pollution. This makes traditional polymer materials limited in the fields of electronics, automobiles, construction and other fields with high requirements for flame retardancy. Therefore, it is necessary to prepare a highly flame retardant and degradable bio-based polymer material. Summary of the invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a highly flame-retardant biodegradable polymer material and a preparation method thereof, wherein L-lactic acid and methacrylic acid are reacted under the action of a catalyst to synthesize lactate, and the lactate is reacted with 2-(2-ethoxyethoxy)ethanol to obtain the corresponding lactate. A compound containing a phosphorus phenanthrene structure is introduced to react with the lactate at a high temperature to generate a bio-based flame retardant, which is added to polylactic acid to improve the flame retardancy of the material, thereby meeting the needs of actual production.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a highly flame retardant biodegradable polymer material, the preparation method comprising:

[0007] Step S1, L-lactic acid, methacrylic acid and p-toluenesulfonic acid monohydrate are added to a reaction solvent in sequence, heated to a first temperature under the protection of an inert gas, and after sufficient reaction, the product is washed with saturated sodium bicarbonate and deionized water, and unreacted solvent and residual water are removed with a rotary evaporator to obtain methacrylic acid lactate;

[0008] Step S2, adding methacrylic acid lactate and 2-(2-ethoxyethoxy)ethanol to cyclohexane, heating at a first temperature for reaction, washing with saturated sodium bicarbonate and then rotary evaporation to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0009] Step S3, heating the phosphophanate group compound to a second temperature until it melts, then adding 2-(2-ethoxyethoxy) methacrylate ethanol, heating to a third temperature, and obtaining a bio-based flame retardant after sufficient reaction;

[0010] Step S4, mixing sodium hydroxide and anhydrous tetrahydrofuran, stirring and mixing at a first stirring speed to obtain a gray solution, adding glycidol dropwise to the gray solution under ice bath conditions, and purging with nitrogen until the gray solution turns white, and dissolving hexachlorocyclotriphosphazene in another portion of anhydrous tetrahydrofuran, and adding dropwise to the white solution under ice bath conditions, placing at room temperature and stirring at a second stirring speed, filtering the product to obtain a viscous liquid, dissolving the viscous liquid in dichloromethane, washing with saturated sodium chloride and drying with anhydrous sodium sulfate, and rotary evaporating to obtain a modified compatibilizer;

[0011] Step S5, after the polylactic acid is placed in a vacuum drying oven and fully dried, the dried polylactic acid, bio-based flame retardant, antioxidant, lubricant and ultraviolet absorber are added to a granulator in sequence, stirred and mixed at a fourth temperature, and then a modified compatibilizer is added, and after continued stirring, the mixture is extruded and granulated and cooled to obtain a highly flame retardant and degradable bio-based polymer material.

[0012] In bio-based flame retardants, an esterification reaction occurs between the hydroxyl group of L-lactic acid and the carboxyl group of methacrylic acid to generate methacrylic acid lactate containing lactic acid groups and unsaturated bonds. By introducing L-lactic acid into the ester structure, the material is made biodegradable, and the unsaturated double bonds in methacrylic acid provide reaction sites for subsequent addition reactions. The reaction of methacrylic acid lactate with 2-(2-ethoxyethoxy)ethanol further extends the molecular chain and maintains the presence of unsaturated double bonds. The phosphophanate group has an active PH group. When it reacts with methacrylic acid lactate ethanol containing unsaturated double bonds, an addition reaction occurs. Due to its larger atomic radius and lower electronegativity, phosphorus atoms can more easily provide electrons to positive centers. Unsaturated double bonds usually have higher electron density. The nucleophilicity of phosphorus enables it to attack the electron-dense area of ​​the unsaturated double bonds, resulting in the opening of the double bonds and the formation of new bonds, generating phosphorus-containing unsaturated polymers. The introduction of phosphorus groups forms stable CP bonds through reactions with unsaturated double bonds, which helps to improve the flame retardant properties of materials.

[0013] In the modified compatibilizer, in the strong alkaline environment of sodium hydroxide, the hydroxyl group of glycidol will undergo a deprotonation reaction. The hydroxide ion of sodium hydroxide removes the proton of one hydroxyl group of glycidol to generate an alcohol salt with a negative charge. This alcohol salt has a high nucleophilicity because its oxygen atom carries a negative charge. At the same time, hexachlorocyclotriphosphazene is a compound with a special structure. It is a ring structure composed of three nitrogen atoms and three phosphorus atoms, and each phosphorus atom is connected to two chlorine atoms, so that the phosphorus atom exhibits a certain electropositivity. In the reaction, the generated alcohol salt will undergo a nucleophilic substitution reaction with the chlorine atom of hexachlorocyclotriphosphazene. The oxygen atom of the alcohol salt is driven by a negative charge and undergoes a nucleophilic attack on the chlorine atom connected to the electropositive phosphorus atom to form an intermediate. The chlorine atom in the reaction acts as a leaving group and is converted into a chloride ion, thereby forming a new phosphate bond. Since phosphate can form a carbon layer at high temperature, it prevents the spread of heat and flame, thereby effectively improving the flame retardant properties of the material.

[0014] As a preferred technical solution of the present invention, in step S1, the amount of L-lactic acid is 20-22 mmol, for example, it can be 20.0 mmol, 20.2 mmol, 20.4 mmol, 20.6 mmol, 20.8 mmol, 21.0 mmol, 21.2 mmol, 21.4 mmol, 21.6 mmol, 21.8 mmol or 22.0 mmol, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] In some optional examples, the amount of methacrylic acid is 10-12 mmol, for example, 10.0 mmol, 10.2 mmol, 10.4 mmol, 10.6 mmol, 10.8 mmol, 11.0 mmol, 11.2 mmol, 11.4 mmol, 11.6 mmol, 11.8 mmol or 12.0 mmol, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] In some optional examples, the mass of the monohydrated p-toluenesulfonic acid is 0.2-0.3 g, for example, it can be 0.20 g, 0.21 g, 0.22 g, 0.23 g, 0.24 g, 0.25 g, 0.26 g, 0.27 g, 0.28 g, 0.29 g or 0.30 g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] In some optional examples, the volume of the reaction solvent is 100-110 mL, for example, it can be 100 mL, 101 mL, 102 mL, 103 mL, 104 mL, 105 mL, 106 mL, 107 mL, 108 mL, 109 mL or 110 mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] In some optional instances, the gas flow rate is 4-6 mL / min, for example, it can be 4.0 mL / min, 4.2 mL / min, 4.4 mL / min, 4.6 mL / min, 4.8 mL / min, 5.0 mL / min, 5.2 mL / min, 5.4 mL / min, 5.6 mL / min, 5.8 mL / min or 6.0 mL / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] In some optional instances, the first temperature is 130-140°C, for example, it can be 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C or 140°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] In some optional examples, the reaction time is 4-5h, for example, it can be 4.0h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] As a preferred technical solution of the present invention, in step S2, the amount of the methacrylic acid lactate is 10-12 mmol, for example, it can be 10.0 mmol, 10.2 mmol, 10.4 mmol, 10.6 mmol, 10.8 mmol, 11.0 mmol, 11.2 mmol, 11.4 mmol, 11.6 mmol, 11.8 mmol or 12.0 mmol, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] In some optional examples, the amount of 2-(2-ethoxyethoxy)ethanol is 12-14 mmol, for example, 12.0 mmol, 12.2 mmol, 12.4 mmol, 12.6 mmol, 12.8 mmol, 13.0 mmol, 13.2 mmol, 13.4 mmol, 13.6 mmol, 13.8 mmol or 14.0 mmol, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] In some optional examples, the volume of the cyclohexane is 80-90 mL, for example, it can be 80 mL, 81 mL, 82 mL, 83 mL, 84 mL, 85 mL, 86 mL, 87 mL, 88 mL, 89 mL or 90 mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] In some optional instances, the first temperature is 130-140°C, for example, it can be 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C or 140°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In some optional examples, the reaction time is 4-5h, for example, it can be 4.0h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] As a preferred technical solution of the present invention, in step S3, the amount of the phosphophanate group compound is 10-12mmol, for example, it can be 10.0mmol, 10.2mmol, 10.4mmol, 10.6mmol, 10.8mmol, 11.0mmol, 11.2mmol, 11.4mmol, 11.6mmol, 11.8mmol or 12.0mmol, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] In some optional instances, the second temperature is 140-150°C, for example, it can be 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 147°C, 148°C, 149°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] In some optional examples, the amount of the 2-(2-ethoxyethoxy) methyl methacrylate ethanol lactate is 10-12 mmol, for example, it can be 10.0 mmol, 10.2 mmol, 10.4 mmol, 10.6 mmol, 10.8 mmol, 11.0 mmol, 11.2 mmol, 11.4 mmol, 11.6 mmol, 11.8 mmol or 12.0 mmol, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] In some optional instances, the third temperature is 160-170°C, for example, it can be 160°C, 161°C, 162°C, 163°C, 164°C, 165°C, 166°C, 167°C, 168°C, 169°C or 170°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] In some optional examples, the reaction time is 5-6h, for example, it can be 5.0h, 5.1h, 5.2h, 5.3h, 5.4h, 5.5h, 5.6h, 5.7h, 5.8h, 5.9h or 6.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] As a preferred technical solution of the present invention, in step S4, the amount of sodium hydroxide is 0.3-0.5 mol, for example, it can be 0.30 mol, 0.32 mol, 0.34 mol, 0.36 mol, 0.38 mol, 0.40 mol, 0.42 mol, 0.44 mol, 0.46 mol, 0.48 mol or 0.50 mol, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] In some optional examples, the volume of the anhydrous tetrahydrofuran is 150-170 mL, for example, it can be 150 mL, 152 mL, 154 mL, 156 mL, 158 mL, 160 mL, 162 mL, 164 mL, 168 mL or 170 mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] In some optional examples, the first stirring speed is 300-400rpm, for example, it can be 300rpm, 310rpm, 320rpm, 330rpm, 340rpm, 350rpm, 360rpm, 370rpm, 380rpm, 390rpm or 400rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In some optional examples, the ratio of the amount of glycidol to the amount of sodium hydroxide is (1-1.2):1, for example, it can be 1:1, 1.02:1, 1.04:1, 1.06:1, 1.08:1, 1.10:1, 1.12:1, 1.14:1, 1.16:1, 1.18:1 or 1.2:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] In some optional examples, the amount of the hexachlorocyclotriphosphazene is 20-22 mmol, for example, 20.0 mmol, 20.2 mmol, 20.4 mmol, 20.6 mmol, 20.8 mmol, 21.0 mmol, 21.2 mmol, 21.4 mmol, 21.6 mmol, 21.8 mmol or 22.0 mmol, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In some optional examples, the volume of the anhydrous tetrahydrofuran is 100-120 mL, for example, it can be 100 mL, 102 mL, 104 mL, 106 mL, 108 mL, 110 mL, 112 mL, 114 mL, 116 mL, 118 mL or 120 mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] In some optional examples, the dropping speed is 4-5 mL / min, for example, it can be 4.0 mL / min, 4.1 mL / min, 4.2 mL / min, 4.3 mL / min, 4.4 mL / min, 4.5 mL / min, 4.6 mL / min, 4.7 mL / min, 4.8 mL / min, 4.9 mL / min or 5.0 mL / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] In some optional examples, the second stirring speed is 200-300 rpm, for example, it can be 200 rpm, 210 rpm, 220 rpm, 230 rpm, 240 rpm, 250 rpm, 260 rpm, 270 rpm, 280 rpm, 290 rpm or 300 rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] In some optional examples, the stirring time is 12-14h, for example, it can be 12.0h, 12.2h, 12.4h, 12.6h, 12.8h, 13.0h, 13.2h, 13.4h, 13.6h, 13.8h or 14.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] As a preferred technical solution of the present invention, in step S5, the vacuum drying temperature is 80-90°C, for example, it can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] In some optional examples, the vacuum drying time is 6-8h, for example, it can be 6.0h, 6.2h, 6.4h, 6.6h, 6.8h, 7.0h, 7.2h, 7.4h, 7.6h, 7.8h or 8.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] In some optional examples, the mass of the polylactic acid is 50-60g, for example, it can be 50g, 51g, 52g, 53g, 54g, 55g, 56g, 57g, 58g, 59g or 60g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] In some optional examples, the mass of the bio-based flame retardant is 10-15g, for example, it can be 10g, 10.5g, 11g, 11.5g, 12.0g, 12.5g, 13.0g, 13.5g, 14.0g, 14.5g or 15.0g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] In some optional examples, the mass of the antioxidant is 0.3-0.5g, for example, it can be 0.30g, 0.32g, 0.34g, 0.36g, 0.38g, 0.40g, 0.42g, 0.44g, 0.46g, 0.48g or 0.50g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] In some optional instances, the mass of the lubricant is 0.1-0.2g, for example, it can be 0.10g, 0.11g, 0.12g, 0.13g, 0.14g, 0.15g, 0.16g, 0.17g, 0.18g, 0.19g or 0.20g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In some optional examples, the mass of the ultraviolet absorber is 0.2-0.3g, for example, it can be 0.20g, 0.21g, 0.22g, 0.23g, 0.24g, 0.25g, 0.26g, 0.27g, 0.28g, 0.29g or 0.30g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] In some optional instances, the fourth temperature is 190-200°C, for example, it can be 190°C, 191°C, 192°C, 193°C, 194°C, 195°C, 196°C, 197°C, 198°C, 199°C or 200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] In some optional examples, the stirring and mixing time is 30-40 min, for example, it can be 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min or 40 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] In some optional examples, the mass of the modified compatibilizer is 2-3g, for example, it can be 2.0g, 2.1g, 2.2g, 2.3g, 2.4g, 2.5g, 2.6g, 2.7g, 2.8g, 2.9g or 3.0g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] In some optional examples, the stirring time is 10-20 min, for example, it can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] In a second aspect, the present invention provides a highly flame retardant biodegradable bio-based polymer material prepared by the method described in the first aspect.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) By introducing phosphophanate group compounds and 2-(2-ethoxyethoxy)ethanol into the material, the material has excellent flame retardant properties. The phosphorus element in the phosphophanate group compound can promote the carbonization reaction on the surface of the material during combustion, forming a stable carbonization layer, which plays a flame retardant role. The appropriate addition of 2-(2-ethoxyethoxy)ethanol enhances the dispersion and compatibility of the flame retardant in the matrix, allowing the flame retardant to work more evenly, thereby improving the overall flame retardant efficiency of the material;

[0054] (2) Polylactic acid is used as the matrix material to give the material good biodegradability. Polylactic acid is a bio-based material derived from renewable resources. It can be degraded by microbial action in the natural environment and eventually decomposed into carbon dioxide and water, reducing pollution to the environment. At the same time, by modifying L-lactic acid, it not only maintains good degradability but also has high flame retardancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A flow chart of a method for preparing a highly flame-retardant and degradable bio-based polymer material provided in Examples 1-8 of the present invention;

[0056] Figure 2 This is a SEM image of a highly flame-retardant biodegradable polymer material prepared in Example 1 of the present invention;

[0057] Figure 3 This is a SEM image of a highly flame retardant and degradable bio-based polymer material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments recorded herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limitations on the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments recorded herein.

[0059] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products, and their brands, specifications and manufacturer information are as follows:

[0060] L-lactic acid, purity ≥88%, Shanghai MacLean Biochemical Technology Co., Ltd.;

[0061] Methacrylic acid, purity ≥99%, Qixiang Huali New Materials Co., Ltd.;

[0062] p-Toluenesulfonic acid monohydrate, purity ≥99%, Qianyan Chemical Technology (Wuhan) Co., Ltd.;

[0063] Cyclohexane, purity ≥99%, Shandong Luoheng Chemical Products Co., Ltd.;

[0064] N 2 , purity ≥99%, Guangzhou Yuejia Gas Co., Ltd.;

[0065] Sodium bicarbonate, purity ≥99%, Hengyang Aijie Technology Co., Ltd.;

[0066] 2-(2-ethoxyethoxy)ethanol, purity ≥99%, Shandong Jinyueyuan New Materials Co., Ltd.;

[0067] 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, purity ≥99%, Hubei Mackays Fine Chemical Technology Co., Ltd.;

[0068] Sodium hydroxide, purity ≥99%, Tianjin Chengyuan Chemical Co., Ltd.;

[0069] Tetrahydrofuran, purity ≥99%, Shandong Yangxin Longtai Chemical Co., Ltd.;

[0070] Glycidol, purity ≥99%, Jiangxi Ruixiang Chemical Co., Ltd.;

[0071] Hexachlorocyclotriphosphazene, purity ≥99%, Hubei Wonder Chemical Co., Ltd.;

[0072] Sodium chloride, purity ≥99%, Yonghua Chemical Co., Ltd.;

[0073] Anhydrous sodium sulfate, purity ≥99%, Shaanxi Didu Pharmaceutical Chemical Co., Ltd.;

[0074] Polylactic acid, purity ≥99%, Pulisi Biotechnology Co., Ltd.;

[0075] Antioxidant 1010, purity ≥99%, Guangzhou Dayin New Materials Co., Ltd.;

[0076] Zinc stearate, purity ≥99%, Dongguan Hanwei Technology Co., Ltd.;

[0077] UV-531, purity ≥99%, Qingdao Zhenguang Functional Materials Technology Co., Ltd.;

[0078] Other raw materials can be purchased from the market.

[0079] Example 1

[0080] This embodiment provides a method for preparing a highly flame-retardant biodegradable polymer material. Figure 1 As shown, the preparation method specifically comprises the following steps:

[0081] Step S1, 20.5 mmol L-lactic acid, 11.3 mmol methacrylic acid and 0.21 g p-toluenesulfonic acid monohydrate are added to 103 mL of cyclohexane in sequence, and heated to 133° C. under nitrogen protection at a gas flow rate of 4.3 mL / min. After fully reacting for 4.3 hours, the product is washed with saturated sodium bicarbonate and deionized water, and the unreacted solvent and residual water are removed by a rotary evaporator to obtain methacrylic acid lactate;

[0082] Step S2, adding 10.5 mmol of methacrylic acid lactate and 12.6 mmol of 2-(2-ethoxyethoxy)ethanol to 82 mL of cyclohexane, heating at 132° C. for reaction for 4.6 h, washing with saturated sodium bicarbonate and rotary evaporation after the reaction to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0083] Step S3, heating 10.8 mmol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 144° C. until it melts, then adding 11.0 mmol of 2-(2-ethoxyethoxy) methyl methacrylate ethanol, heating to 166° C., and fully reacting for 5.2 hours to obtain a bio-based flame retardant;

[0084] Step S4, 0.33 mol of sodium hydroxide is mixed with 155 mL of anhydrous tetrahydrofuran, and the mixture is stirred at 330 rpm to obtain a gray solution. Under an ice bath condition, 0.35 mol of glycidol is added dropwise to the gray solution, and nitrogen is purged until the gray solution turns white. Meanwhile, 20.6 mmol of hexachlorocyclotriphosphazene is dissolved in another 108 mL of anhydrous tetrahydrofuran and added dropwise to the white solution under an ice bath condition, and the mixture is placed at room temperature and stirred at 240 rpm for 12.6 h. The product is filtered to obtain a viscous liquid, and the viscous liquid is dissolved in dichloromethane, washed with saturated sodium chloride and dried with anhydrous sodium sulfate, and a modified compatibilizer is obtained by rotary evaporation;

[0085] Step S5, placing the polylactic acid in a vacuum drying oven at 82°C for sufficient drying for 6.3 hours, adding 52g of the dried polylactic acid, 11.6g of the bio-based flame retardant, 0.38g of the antioxidant 1010, 0.14g of zinc stearate and 0.21g of UV-531 into a granulator in sequence, stirring and mixing at 192°C for 33min, then adding 2.4g of the modified compatibilizer, continuing to stir for 12min, then extruding and granulating and cooling to obtain a highly flame-retardant biodegradable polymer material.

[0086] Figure 2 , Figure 3 This is a SEM image of a highly flame retardant and degradable bio-based polymer material prepared in this example.

[0087] Example 2

[0088] This embodiment provides a method for preparing a highly flame-retardant biodegradable polymer material. Figure 1 As shown, the preparation method specifically comprises the following steps:

[0089] Step S1, 20.9 mmol L-lactic acid, 10.3 mmol methacrylic acid and 0.26 g p-toluenesulfonic acid monohydrate are added to 107 mL of cyclohexane in sequence, and heated to 135° C. under nitrogen protection at a gas flow rate of 4.8 mL / min. After fully reacting for 4.1 hours, the product is washed with saturated sodium bicarbonate and deionized water, and the unreacted solvent and residual water are removed by a rotary evaporator to obtain methacrylic acid lactate;

[0090] Step S2, adding 10.8 mmol of methacrylic acid lactate and 13.2 mmol of 2-(2-ethoxyethoxy)ethanol to 86 mL of cyclohexane, heating at 137° C. for reaction for 4.2 h, washing with saturated sodium bicarbonate and rotary evaporation after the reaction to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0091] Step S3, heating 11.2 mmol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 141° C. until it melts, then adding 11.4 mmol of 2-(2-ethoxyethoxy) methyl methacrylate ethanol, heating to 162° C., and fully reacting for 5.4 hours to obtain a bio-based flame retardant;

[0092] Step S4, 0.39 mol of sodium hydroxide was mixed with 158 mL of anhydrous tetrahydrofuran, and the mixture was stirred at 360 rpm to obtain a gray solution. Under an ice bath condition, 0.44 mol of glycidol was added dropwise to the gray solution, and nitrogen was used to purge until the gray solution turned white. Meanwhile, 21.3 mmol of hexachlorocyclotriphosphazene was dissolved in another 112 mL of anhydrous tetrahydrofuran and added dropwise to the white solution under an ice bath condition, and the mixture was placed at room temperature and stirred at 260 rpm for 13.1 h. The product was filtered to obtain a viscous liquid, and the viscous liquid was dissolved in dichloromethane, washed with saturated sodium chloride and dried with anhydrous sodium sulfate, and a modified compatibilizer was obtained by rotary evaporation;

[0093] Step S5, placing the polylactic acid in a vacuum drying oven at 85°C for sufficient drying for 7.1 hours, adding 56g of the dried polylactic acid, 13.4g of the bio-based flame retardant, 0.32g of the antioxidant 1010, 0.12g of zinc stearate and 0.25g of UV-531 into a granulator in sequence, stirring and mixing at 195°C for 37 minutes, then adding 2.1g of the modified compatibilizer, continuing to stir for 16 minutes, then extruding and granulating and cooling to obtain a highly flame-retardant biodegradable polymer material.

[0094] Example 3

[0095] This embodiment provides a method for preparing a highly flame-retardant biodegradable polymer material. Figure 1 As shown, the preparation method specifically comprises the following steps:

[0096] Step S1, 20.7 mmol L-lactic acid, 10.6 mmol methacrylic acid and 0.23 g p-toluenesulfonic acid monohydrate are added to 105 mL cyclohexane in sequence, and heated to 132° C. under nitrogen protection at a gas flow rate of 4.4 mL / min. After fully reacting for 4.5 hours, the product is washed with saturated sodium bicarbonate and deionized water, and the unreacted solvent and residual water are removed by a rotary evaporator to obtain methacrylic acid lactate;

[0097] Step S2, adding 11.2 mmol of methacrylic acid lactate and 13.0 mmol of 2-(2-ethoxyethoxy)ethanol to 80 mL of cyclohexane, heating at 135° C. for reaction for 4.7 h, washing with saturated sodium bicarbonate and rotary evaporation after the reaction to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0098] Step S3, heating 10.4 mmol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 147° C. until it melts, then adding 10.7 mmol of 2-(2-ethoxyethoxy) methacrylate ethanol, heating to 164° C., and fully reacting for 5.8 hours to obtain a bio-based flame retardant;

[0099] Step S4, 0.42 mol of sodium hydroxide was mixed with 162 mL of anhydrous tetrahydrofuran, and the mixture was stirred at 340 rpm to obtain a gray solution. Under an ice bath condition, 0.46 mol of glycidol was added dropwise to the gray solution, and nitrogen was used to purge until the gray solution turned white. Meanwhile, 20.4 mmol of hexachlorocyclotriphosphazene was dissolved in another 104 mL of anhydrous tetrahydrofuran and added dropwise to the white solution under an ice bath condition, and the mixture was placed at room temperature and stirred at 220 rpm for 13.6 h. The product was filtered to obtain a viscous liquid, and the viscous liquid was dissolved in dichloromethane, washed with saturated sodium chloride and dried with anhydrous sodium sulfate, and a modified compatibilizer was obtained by rotary evaporation;

[0100] Step S5, placing the polylactic acid in a vacuum drying oven at 83°C for sufficient drying for 6.6 hours, adding 51g of the dried polylactic acid, 12.5g of the bio-based flame retardant, 0.41g of the antioxidant 1010, 0.11g of zinc stearate and 0.22g of UV-531 into a granulator in sequence, stirring and mixing at 190°C for 31min, then adding 2.3g of the modified compatibilizer, continuing to stir for 13min, then extruding and granulating and cooling to obtain a highly flame-retardant biodegradable polymer material.

[0101] Example 4

[0102] This embodiment provides a method for preparing a highly flame-retardant biodegradable polymer material. Figure 1 As shown, the preparation method specifically comprises the following steps:

[0103] Step S1, 20.3 mmol L-lactic acid, 10.8 mmol methacrylic acid and 0.21 g p-toluenesulfonic acid monohydrate are added to 100 mL of cyclohexane in sequence, and heated to 131° C. under nitrogen protection at a gas flow rate of 4.1 mL / min. After fully reacting for 4.7 hours, the product is washed with saturated sodium bicarbonate and deionized water, and the unreacted solvent and residual water are removed by a rotary evaporator to obtain methacrylic acid lactate;

[0104] Step S2, adding 11.3 mmol of methacrylic acid lactate and 12.6 mmol of 2-(2-ethoxyethoxy)ethanol to 88 mL of cyclohexane, heating at 132° C. for reaction for 4.4 h, washing with saturated sodium bicarbonate and rotary evaporation after the reaction to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0105] Step S3, heating 10.9 mmol 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 144° C. until it melts, then adding 11.1 mmol 2-(2-ethoxyethoxy) methacrylate ethanol, heating to 163° C., and fully reacting for 5.2 hours to obtain a bio-based flame retardant;

[0106] Step S4, 0.34 mol of sodium hydroxide was mixed with 155 mL of anhydrous tetrahydrofuran, and the mixture was stirred at 320 rpm to obtain a gray solution. Under ice bath conditions, 0.37 mol of glycidol was added dropwise to the gray solution, and nitrogen was used to purge until the gray solution turned white. Meanwhile, 20.9 mmol of hexachlorocyclotriphosphazene was dissolved in another 114 mL of anhydrous tetrahydrofuran and added dropwise to the white solution under ice bath conditions. The mixture was placed at room temperature and stirred at 210 rpm for 12.3 h. The product was filtered to obtain a viscous liquid. The viscous liquid was dissolved in dichloromethane, washed with saturated sodium chloride and dried with anhydrous sodium sulfate, and rotary evaporated to obtain a modified compatibilizer;

[0107] Step S5, placing the polylactic acid in a vacuum drying oven at 81°C for sufficient drying for 7.4 hours, adding 57g of the dried polylactic acid, 14.6g of the bio-based flame retardant, 0.37g of the antioxidant 1010, 0.14g of zinc stearate and 0.20g of UV-531 into a granulator in sequence, stirring and mixing at 193°C for 37 minutes, then adding 2.5g of a modified compatibilizer, continuing to stir for 19 minutes, then extruding and granulating and cooling to obtain a highly flame-retardant biodegradable polymer material.

[0108] Example 5

[0109] This embodiment provides a method for preparing a highly flame-retardant biodegradable polymer material. Figure 1 As shown, the preparation method specifically comprises the following steps:

[0110] Step S1, 21.1 mmol L-lactic acid, 11.5 mmol methacrylic acid and 0.26 g p-toluenesulfonic acid monohydrate are added to 105 mL of cyclohexane in sequence, and heated to 137° C. under nitrogen protection at a gas flow rate of 5.0 mL / min. After fully reacting for 4.0 h, the product is washed with saturated sodium bicarbonate and deionized water, and the unreacted solvent and residual water are removed by a rotary evaporator to obtain methacrylic acid lactate;

[0111] Step S2, adding 10.4 mmol of methacrylic acid lactate and 13.1 mmol of 2-(2-ethoxyethoxy)ethanol to 90 mL of cyclohexane, heating at 137° C. for reaction for 4.8 h, washing with saturated sodium bicarbonate and rotary evaporation after the reaction to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0112] Step S3, heating 11.2 mmol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 142° C. until it melts, then adding 11.5 mmol of 2-(2-ethoxyethoxy) methyl methacrylate ethanol, heating to 160° C., and fully reacting for 5.8 hours to obtain a bio-based flame retardant;

[0113] Step S4, 0.38 mol of sodium hydroxide was mixed with 161 mL of anhydrous tetrahydrofuran, and the mixture was stirred at 350 rpm to obtain a gray solution. Under ice bath conditions, 0.41 mol of glycidol was added dropwise to the gray solution, and nitrogen was used to purge until the gray solution turned white. Meanwhile, 21.4 mmol of hexachlorocyclotriphosphazene was dissolved in another 106 mL of anhydrous tetrahydrofuran and added dropwise to the white solution under ice bath conditions. The mixture was placed at room temperature and stirred at 250 rpm for 13.2 h. The product was filtered to obtain a viscous liquid. The viscous liquid was dissolved in dichloromethane, washed with saturated sodium chloride and dried with anhydrous sodium sulfate, and rotary evaporated to obtain a modified compatibilizer;

[0114] Step S5, placing the polylactic acid in a vacuum drying oven at 84°C for sufficient drying for 6.3 hours, adding 52g of the dried polylactic acid, 13.1g of the bio-based flame retardant, 0.37g of the antioxidant 1010, 0.15g of zinc stearate and 0.27g of UV-531 into a granulator in sequence, stirring and mixing at 195°C for 33 minutes, then adding 2.4g of the modified compatibilizer, continuing to stir for 13 minutes, then extruding and granulating and cooling to obtain a highly flame-retardant biodegradable polymer material.

[0115] Example 6

[0116] This embodiment provides a method for preparing a highly flame-retardant biodegradable polymer material. Figure 1 As shown, the preparation method specifically comprises the following steps:

[0117] Step S1, 21.7 mmol L-lactic acid, 11.4 mmol methacrylic acid and 0.22 g p-toluenesulfonic acid monohydrate are added to 110 mL of cyclohexane in sequence, and heated to 138° C. under nitrogen protection at a gas flow rate of 5.3 mL / min. After fully reacting for 4.7 hours, the product is washed with saturated sodium bicarbonate and deionized water, and the unreacted solvent and residual water are removed by a rotary evaporator to obtain methacrylic acid lactate;

[0118] Step S2, adding 10.9 mmol of methacrylic acid lactate and 13.6 mmol of 2-(2-ethoxyethoxy)ethanol to 86 mL of cyclohexane, heating at 133° C. for reaction for 4.4 h, washing with saturated sodium bicarbonate and rotary evaporation after the reaction to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0119] Step S3, heating 11.6 mmol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 146° C. until it melts, then adding 11.8 mmol of 2-(2-ethoxyethoxy) methacrylate ethanol, heating to 167° C., and fully reacting for 5.7 hours to obtain a bio-based flame retardant;

[0120] Step S4, 0.44 mol of sodium hydroxide was mixed with 165 mL of anhydrous tetrahydrofuran, and the mixture was stirred at 380 rpm to obtain a gray solution. Under an ice bath condition, 0.48 mol of glycidol was added dropwise to the gray solution, and nitrogen was used to purge until the gray solution turned white. Meanwhile, 20.2 mmol of hexachlorocyclotriphosphazene was dissolved in another 113 mL of anhydrous tetrahydrofuran and added dropwise to the white solution under an ice bath condition, and the mixture was placed at room temperature and stirred at 240 rpm for 13.7 h. The product was filtered to obtain a viscous liquid, and the viscous liquid was dissolved in dichloromethane, washed with saturated sodium chloride and dried with anhydrous sodium sulfate, and a modified compatibilizer was obtained by rotary evaporation;

[0121] Step S5, placing the polylactic acid in a vacuum drying oven at 88°C for sufficient drying for 6.7 hours, adding 55g of the dried polylactic acid, 14.5g of the bio-based flame retardant, 0.42g of the antioxidant 1010, 0.18g of zinc stearate and 0.23g of UV-531 into a granulator in sequence, stirring and mixing at 197°C for 36 minutes, then adding 2.6g of the modified compatibilizer, continuing to stir for 15 minutes, then extruding and granulating and cooling to obtain a highly flame-retardant biodegradable polymer material.

[0122] Example 7

[0123] This embodiment provides a method for preparing a highly flame-retardant biodegradable polymer material. Figure 1As shown, the preparation method specifically comprises the following steps:

[0124] Step S1, 20.9 mmol L-lactic acid, 10.3 mmol methacrylic acid and 0.24 g p-toluenesulfonic acid monohydrate are added to 110 mL of cyclohexane in sequence, and heated to 134° C. under nitrogen protection at a gas flow rate of 5.5 mL / min. After fully reacting for 4.5 hours, the product is washed with saturated sodium bicarbonate and deionized water, and the unreacted solvent and residual water are removed by a rotary evaporator to obtain methacrylic acid lactate;

[0125] Step S2, adding 11.6 mmol of methacrylic acid lactate and 13.4 mmol of 2-(2-ethoxyethoxy)ethanol to 88 mL of cyclohexane, heating at 131° C. for reaction for 4.9 h, washing with saturated sodium bicarbonate and rotary evaporation after the reaction to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0126] Step S3, heating 11.2 mmol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 147° C. until it melts, then adding 11.4 mmol of 2-(2-ethoxyethoxy) methacrylate ethanol, heating to 164° C., and fully reacting for 5.3 hours to obtain a bio-based flame retardant;

[0127] Step S4, 0.37 mol of sodium hydroxide was mixed with 156 mL of anhydrous tetrahydrofuran, and the mixture was stirred at 320 rpm to obtain a gray solution. Under an ice bath condition, 0.41 mol of glycidol was added dropwise to the gray solution, and nitrogen was used to purge until the gray solution turned white. Meanwhile, 21.1 mmol of hexachlorocyclotriphosphazene was dissolved in another 110 mL of anhydrous tetrahydrofuran and added dropwise to the white solution under an ice bath condition, and the mixture was placed at room temperature and stirred at 260 rpm for 12.7 h. The product was filtered to obtain a viscous liquid, and the viscous liquid was dissolved in dichloromethane, washed with saturated sodium chloride and dried with anhydrous sodium sulfate, and a modified compatibilizer was obtained by rotary evaporation;

[0128] Step S5, placing the polylactic acid in a vacuum drying oven at 85°C for sufficient drying for 6.7 hours, adding 58g of the dried polylactic acid, 11.9g of the bio-based flame retardant, 0.33g of the antioxidant 1010, 0.13g of zinc stearate and 0.26g of UV-531 into a granulator in sequence, stirring and mixing at 193°C for 32 minutes, then adding 2.2g of the modified compatibilizer, continuing to stir for 16 minutes, then extruding and granulating and cooling to obtain a highly flame-retardant biodegradable polymer material.

[0129] Example 8

[0130] This embodiment provides a method for preparing a highly flame-retardant biodegradable polymer material. Figure 1 As shown, the preparation method specifically comprises the following steps:

[0131] Step S1, 21.3 mmol L-lactic acid, 11.5 mmol methacrylic acid and 0.28 g p-toluenesulfonic acid monohydrate are added to 107 mL of cyclohexane in sequence, and heated to 133° C. under nitrogen protection at a gas flow rate of 4.7 mL / min. After fully reacting for 4.2 hours, the product is washed with saturated sodium bicarbonate and deionized water, and the unreacted solvent and residual water are removed by a rotary evaporator to obtain methacrylic acid lactate;

[0132] Step S2, adding 11.6 mmol of methacrylic acid lactate and 12.7 mmol of 2-(2-ethoxyethoxy)ethanol to 86 mL of cyclohexane, heating at 135° C. for reaction for 4.4 h, washing with saturated sodium bicarbonate and rotary evaporation after the reaction to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol;

[0133] Step S3, heating 10.7 mmol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to 143° C. until it melts, then adding 10.6 mmol of 2-(2-ethoxyethoxy) methyl methacrylate ethanol, heating to 166° C., and fully reacting for 5.8 hours to obtain a bio-based flame retardant;

[0134] Step S4, 0.46 mol of sodium hydroxide was mixed with 163 mL of anhydrous tetrahydrofuran, and the mixture was stirred at 370 rpm to obtain a gray solution. Under ice bath conditions, 0.52 mol of glycidol was added dropwise to the gray solution, and nitrogen was used to purge until the gray solution turned white. Meanwhile, 21.6 mmol of hexachlorocyclotriphosphazene was dissolved in another 114 mL of anhydrous tetrahydrofuran and added dropwise to the white solution under ice bath conditions. The mixture was placed at room temperature and stirred at 240 rpm for 13.4 h. The product was filtered to obtain a viscous liquid. The viscous liquid was dissolved in dichloromethane, washed with saturated sodium chloride and dried with anhydrous sodium sulfate, and rotary evaporated to obtain a modified compatibilizer;

[0135] Step S5, placing the polylactic acid in a vacuum drying oven at 87°C for sufficient drying for 6.6 hours, adding 59g of the dried polylactic acid, 13.4g of the bio-based flame retardant, 0.42g of the antioxidant 1010, 0.17g of zinc stearate and 0.28g of UV-531 into a granulator in sequence, stirring and mixing at 196°C for 38 minutes, then adding 2.5g of a modified compatibilizer, continuing to stir for 18 minutes, then extruding and granulating and cooling to obtain a highly flame-retardant biodegradable polymer material.

[0136] Comparative Example 1

[0137] This embodiment provides a highly flame retardant biodegradable polymer material, which differs from Example 1 in that in step S2, the amount of 2-(2-ethoxyethoxy)ethanol is adjusted to 15.6 mmol. Compared with Example 1, the amount of 2-(2-ethoxyethoxy)ethanol in this embodiment is increased by 3 mmol, and other process parameters and operating conditions are exactly the same as those in Example 1.

[0138] Comparative Example 2

[0139] This embodiment provides a highly flame retardant biodegradable polymer material, which differs from Example 1 in that in step S2, the amount of 2-(2-ethoxyethoxy)ethanol is adjusted to 9.6 mmol. Compared with Example 1, the amount of 2-(2-ethoxyethoxy)ethanol in this embodiment is reduced by 3 mmol, and other process parameters and operating conditions are exactly the same as those in Example 1.

[0140] Comparative Example 3

[0141] This embodiment provides a highly flame retardant and biodegradable polymer material, which differs from Example 1 in that in step S5, the mass of the modified compatibilizer is adjusted to 3.4 g. Compared with Example 1, the mass of the modified compatibilizer in this embodiment is increased by 1 g, and the increased mass is deducted from the polylactic acid, bio-based flame retardant, antioxidant 1010, zinc stearate and UV-531 in equal proportion, so that the mass ratio between the other components except the modified compatibilizer remains unchanged, and the other process parameters and operating conditions are exactly the same as those in Example 1.

[0142] Comparative Example 4

[0143] This embodiment provides a highly flame retardant and biodegradable polymer material, which differs from Example 1 in that in step S5, the mass of the modified compatibilizer is adjusted to 1.4 g. Compared with Example 1, the mass of the modified compatibilizer in this embodiment is reduced by 1 g, and the reduced mass is added in equal proportion to polylactic acid, bio-based flame retardant, antioxidant 1010, zinc stearate and UV-531, so that the mass ratio between the other components except the modified compatibilizer remains unchanged, and other process parameters and operating conditions are exactly the same as those in Example 1.

[0144] The limiting oxygen index of the composite materials prepared by Examples 1-8 and Comparative Examples 1-4 was tested according to the national standard GB / T 2406.2-2009; the flame retardant properties of the composite materials prepared by Examples 1-8 and Comparative Examples 1-4 were tested according to GB / T 2408-2021; the mechanical properties of the composite materials prepared by Examples 1-8 and Comparative Examples 1-4 were tested according to GB / T 1040.1-2018. The test results are shown in Table 1.

[0145] Table 1 Test results of Examples 1-8 and Comparative Examples 1-4 A highly flame retardant biodegradable polymer material

[0146]

[0147] It can be seen from the data of Example 1, Comparative Example 1 and Comparative Example 2 that the flame retardant effect of the composite material obtained in Comparative Example 1 is worse than that of Example 1, the tensile strength is lower than that of Example 1, and the elongation at break is higher than that of Example 1; the flame retardant effect of the composite material obtained in Comparative Example 2 is worse than that of Example 1, and the tensile strength and elongation at break are both lower than those of Example 1. This is because 2-(2-ethoxyethoxy)ethanol plays the role of chain extension and introduction of flexible segments in the reaction. The excessive ethoxyethanol in Comparative Example 1 will cause the molecular chain of the material to contain more flexible parts, reduce the rigidity of the molecular chain, and the increase of flexible segments may weaken the carbonization effect of the material at high temperature, causing the material to be more easily decomposed during the combustion process, and it is difficult to form an effective thermal insulation protective layer. 2-(2-ethoxyethoxy)ethanol can provide a certain flexibility for the material, so that the material can maintain structural integrity during the flame retardant process. The insufficient addition of 2-(2-ethoxyethoxy)ethanol in Comparative Example 2 will lead to insufficient flexible segments in the material, and may also cause uneven distribution of the flame retardant, reduce the dispersion and stabilization effect of the flame retardant, and thus affect the overall flame retardant effect.

[0148] It can be seen from the data of Example 1, Comparative Example 3 and Comparative Example 4 that the flame retardant effect of the composite material obtained in Comparative Example 3 is lower than that of Example 1, and the tensile strength and elongation at break remain basically the same as those of Example 1; the flame retardant effect, tensile strength and elongation at break of the composite material obtained in Comparative Example 4 are all lower than those of Example 1. The modified compatibilizer usually improves the comprehensive properties of the material by enhancing the compatibility of the auxiliary agent with the polymer matrix. The excessive amount of compatibilizer in Comparative Example 3 may dilute the concentration of the flame retardant and reduce the effective action sites of the flame retardant in the polymer, which will cause the flame retardant to be unable to fully exert its flame retardant effect, especially the insufficient carbon layer formed at high temperature, which reduces the flame retardant effect. The small amount of modified compatibilizer in Comparative Example 4 cannot effectively help the flame retardant to be evenly dispersed in the polymer matrix. This may cause the local concentration of the flame retardant to be too high or too low, and the area with too much flame retardant may cause the mechanical properties of the material to deteriorate, and the area with too little flame retardant may cause the local flame retardant effect to be poor, and the flame retardant may not be fully combined with the polymer matrix, and the flame retardant may be difficult to form a continuous carbonized layer, which reduces the flame retardant effect.

[0149] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a highly flame-retardant biodegradable polymer material, characterized in that: The preparation method is: Step S1, adding L-lactic acid, methacrylic acid and p-toluenesulfonic acid monohydrate to a reaction solvent in sequence, heating to a first temperature under the protection of an inert gas, washing the product after sufficient reaction, and obtaining methacrylic acid lactate; Step S2, adding methacrylic acid lactate and 2-(2-ethoxyethoxy)ethanol to a reaction solvent, heating at a first temperature for reaction, washing and rotary evaporation after the reaction is completed, to obtain 2-(2-ethoxyethoxy)methacrylic acid lactate ethanol; Step S3, heating the phosphophanate group compound to a second temperature until it melts, then adding 2-(2-ethoxyethoxy) methacrylate ethanol, heating to a third temperature, and obtaining a bio-based flame retardant after sufficient reaction; Step S4, mixing sodium hydroxide and anhydrous tetrahydrofuran with stirring to obtain a gray solution, dripping glycidol into the gray solution under ice bath conditions, and purging with nitrogen until the gray solution turns white, dissolving hexachlorocyclotriphosphazene in another portion of anhydrous tetrahydrofuran and dripping into the white solution under ice bath conditions, and stirring sufficiently at room temperature, filtering the product to obtain a viscous liquid, dissolving the viscous liquid in dichloromethane, washing with saturated sodium chloride and drying with anhydrous sodium sulfate to obtain a modified compatibilizer; Step S5, placing the polylactic acid in a vacuum drying oven to be fully dried, adding the dried polylactic acid, bio-based flame retardant, antioxidant, lubricant and ultraviolet absorber into a granulator in sequence, stirring and mixing at the fourth temperature, adding a modified compatibilizer, continuing to stir, extrude and granulate and cool, to obtain a highly flame retardant and degradable bio-based polymer material.

2. The method for preparing a highly flame-retardant biodegradable polymer material according to claim 1, characterized in that: In step S1: The amount of L-lactic acid is 20-22 mmol; The amount of methacrylic acid is 10-12 mmol; The mass of the p-toluenesulfonic acid monohydrate is 0.2-0.3 g.

3. The method for preparing a highly flame-retardant biodegradable polymer material according to claim 1, characterized in that: In step S1: The reaction solvent is cyclohexane, with a volume of 100-110 mL; The inert gas is N2, and the gas flow rate is 4-6 mL / min; The first temperature is 130-140°C; The reaction time is 4-5h.

4. The method for preparing a highly flame-retardant biodegradable polymer material according to claim 1, characterized in that: In step S2: The amount of the lactic acid methacrylate is 10-12 mmol; The amount of 2-(2-ethoxyethoxy)ethanol is 12-14 mmol; The reaction solvent is cyclohexane, with a volume of 80-90 mL; The first temperature is 130-140°C; The reaction time is 4-5h.

5. The method for preparing a highly flame-retardant biodegradable polymer material according to claim 1, characterized in that: In step S3: The phosphaphenanthrene group compound is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and the amount of the substance is 10-12 mmol; The second temperature is 140-150°C; The amount of the substance of 2-(2-ethoxyethoxy) methacrylic acid lactate ethanol is 10-12 mmol; The third temperature is 160-170°C; The reaction time is 5-6h.

6. The method for preparing a highly flame-retardant biodegradable polymer material according to claim 1, characterized in that: In step S4: The amount of sodium hydroxide is 0.3-0.5 mol; The volume of the anhydrous tetrahydrofuran is 150-170 mL; The ratio of the amount of glycidol to the amount of sodium hydroxide is (1-1.2):1; The amount of the hexachlorocyclotriphosphazene is 20-22 mmol.

7. The method for preparing a highly flame-retardant biodegradable polymer material according to claim 1, characterized in that: In step S4: The volume of the anhydrous tetrahydrofuran is 100-120 mL; The dropping speed is 4-5 mL / min; The stirring time is 12-14h.

8. The method for preparing a highly flame-retardant biodegradable polymer material according to claim 1, characterized in that: In step S5: The vacuum drying temperature is 80-90°C; The vacuum drying time is 6-8h; The mass of the polylactic acid is 50-60g; The mass of the bio-based flame retardant is 10-15g; The antioxidant is antioxidant 1010, with a mass of 0.3-0.5g; The lubricant is zinc stearate, with a mass of 0.1-0.2g.

9. The method for preparing a highly flame-retardant biodegradable polymer material according to claim 1, characterized in that: In step S5: The ultraviolet absorber is UV-531, with a mass of 0.2-0.3g; The fourth temperature is 190-200° C.; The stirring and mixing time is 30-40min; The mass of the modified compatibilizer is 2-3g; The stirring time is 10-20 min.

10. A highly flame retardant and degradable bio-based polymer material obtained according to the preparation method according to any one of claims 1 to 9.

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