A highly efficient degradable PP composite material and its preparation method

Abstract

This invention relates to a highly efficient degradable PP composite material and its preparation method, belonging to the field of polymer composite material technology. The composite material comprises: 39-46 wt% core-shell composite degradable filler, 3.5-4.2 wt% compatibilizer, 1.8-2.3 wt% lubricant, 0.12-0.15 wt% nucleating agent, and 0.08-0.1 wt% antioxidant, with the balance being PP resin. The core-shell composite degradable filler is prepared by the addition reaction of γ-mercaptopropyltriethoxysilane and diallylamine to form a double-bridged agglomerant, which is hydrolyzed and coupled with starch to form starch cluster particles doped with the double-bridged agglomerant. The sulfide and amine structures introduced by the double-bridged agglomerant form a chelating effect, enriching stannous chloride on the surface of the starch cluster particles, thus forming an in-situ polylactic acid shell coating. After blending, the modified product maintains good mechanical properties, and waste products can be efficiently degraded through simple crushing.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically, it relates to a highly efficient degradable PP composite material and its preparation method. Background Technology

[0002] Polypropylene (PP), as a general-purpose thermoplastic, is widely used in packaging, automotive, and home appliance industries due to its excellent mechanical properties, chemical resistance, and low cost. However, traditional PP materials are difficult to degrade in the natural environment.

[0003] To alleviate environmental pressure, existing technologies mainly achieve composite modification by introducing biodegradable materials into the PP matrix. These technologies fall into two categories: First, they use natural materials such as starch and wood flour as fillers. While these materials possess rapid biodegradability, their poor compatibility with the hydrophilicity of the PP matrix leads to a significant decrease in the mechanical properties of the composite material, limiting its application in mechanically sensitive applications. Second, they blend biodegradable polymers such as polylactic acid and polycaprolactone with PP. These materials have good compatibility with PP and minimal impact on mechanical properties, but their slow degradation rate makes it difficult to meet practical degradation requirements. Therefore, existing technologies generally face the core contradiction of synergistically optimizing "degradation efficiency" and "material performance," urgently requiring an innovative solution that can maintain the mechanical properties of the PP matrix while achieving efficient degradation. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a highly efficient degradable PP composite material and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A highly efficient degradable PP composite material, comprising: 39-46 wt% core-shell composite degradable filler, 3.5-4.2 wt% compatibilizer, 1.8-2.3 wt% lubricant, 0.12-0.15 wt% nucleating agent and 0.08-0.1 wt% antioxidant, with the balance being PP resin.

[0007] The core-shell composite degradable filler is prepared by the following method:

[0008] Step A1: Mix diallylamine, γ-mercaptopropyltriethoxysilane, and anhydrous acetone under a dry atmosphere, using a stirring pressure of 300-400 mW / cm². 2 After UV irradiation, photosensitizer was slowly added at room temperature and stirred for 12-15 hours. Then, acetone was removed by evaporation to obtain the double-bridged agglomerant.

[0009] In step A1 above, the feed ratio of diallylamine, γ-mercaptopropyltriethoxysilane, photosensitizer, and anhydrous acetone is 0.1 mol: 0.2 mol: 0.16-0.22 g: 350-400 mL. Under UV irradiation initiation, γ-mercaptopropyltriethoxysilane reacts with diallylamine in an addition reaction. The specific reaction route is as follows:

[0010]

[0011] Step A2: Premix the double-bridge agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution, adjust the pH of the premix to 3-4 with hydrochloric acid, add starch and ultrasonically disperse, then stir at 120-150 rpm for 2-2.5 h, centrifuge to remove the supernatant, spray dry the bottom concentrate to obtain modified starch;

[0012] In step A2 above, the feed ratio of starch, double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution is 50g: 3.6-4.2g: 1.1-1.5g: 220-260mL, and the mass fraction of tetrahydrofuran aqueous solution is 50-60%. The terminal ethoxysilane structure of the double-bridged agglomerator is hydrolyzed and coupled with starch to form starch cluster particles doped with double-bridged agglomerator.

[0013] Step A3: Premix modified starch, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide, then add L-lactide in chloroform solution and mix well. Under nitrogen protection, heat to 150-160℃ and stir for 6-7 hours. Then reduce the pressure to 50 Pa and heat to 210-220℃ to continue the reaction for 3.5-4 hours. Discharge, cool, wash and dry to obtain core-shell composite degradable filler.

[0014] In step A3 above, the feed ratio of modified starch, L-lactide, stannous chloride, p-toluenesulfonic acid, and dimethyl sulfoxide is 50g: 8.5-11g: 0.18-0.24g: 0.1-0.13g: 150-200mL. The sulfide and amine structures introduced by the double-bridged agglomerator in the modified starch form a chelating effect, enriching stannous chloride on the surface of the modified starch. This promotes the initiation of ring-opening polymerization of L-lactide on the surface of the modified starch, forming a polylactic acid-coated starch composite structure.

[0015] Preferably, the compatibilizer is maleic anhydride-grafted polypropylene, which plays a good compatibilizing role between the PP matrix and the polylactic acid shell of the core-shell composite degradable filler.

[0016] Preferably, the nucleating agent is an amide nucleating agent, which promotes the formation of β-phase crystals in the PP matrix, thereby improving the overall strength and toughness of the composite material.

[0017] A method for preparing a highly efficient degradable PP composite material is as follows: PP resin, compatibilizer, lubricant, nucleating agent and antioxidant are premixed and fed from the main feed port of an extruder, and core-shell composite degradable filler is fed from the side feed port of the extruder, and the mixture is co-extruded to obtain a highly efficient degradable PP composite material.

[0018] Preferably, the barrel temperature zones of the extruder are set as follows: Zone 1 170-180℃, Zone 2 180-190℃, Zone 3 190-200℃, Zone 4 200-210℃, Zone 5 200-210℃, Zone 6 200-210℃, and Die head 210-220℃.

[0019] The beneficial effects of this invention are:

[0020] This invention achieves a synergistic improvement in the degradation efficiency and mechanical properties of PP composite materials through the design of a core-shell composite degradable filler and its specific preparation process. The core-shell composite degradable filler is prepared by the addition reaction of γ-mercaptopropyltriethoxysilane and diallylamine to form a double-bridged agglomerant with branched triethoxysilane. This agglomerant hydrolyzes and couples with starch to form starch cluster particles doped with the double-bridged agglomerant, i.e., modified starch. The sulfide and amine structures introduced by the double-bridged agglomerant in the modified starch form a chelating effect, enriching stannous chloride on the surface of the modified starch. This promotes the initiation of ring-opening polymerization of L-lactide on the modified starch surface, forming a polylactic acid-coated starch composite structure. Compared with existing technologies, the shell of the core-shell composite degradable filler is polylactic acid (PLA), which has better compatibility with the PP matrix than natural starch, effectively alleviating the interface defect problems caused by traditional starch fillers and reducing the burden on the composite material. The deterioration of key mechanical properties such as tensile strength and impact toughness in composite materials, coupled with the expansion of microcracks formed after the PLA shell fractures into the PP matrix, increases the specific surface area of ​​the material. This promotes the contact between PP segments and oxygen, moisture, and microorganisms, overcoming the degradation inertia of traditional PP due to its high crystallinity. Furthermore, after the product is broken, the brittle PLA shell fractures preferentially, exposing the internal starch core. Microorganisms rapidly multiply using starch as a nutrient source, forming a localized acidic microenvironment that accelerates the enzymatic and hydrolytic degradation of the PLA shell. Simultaneously, the low molecular weight products generated by PLA degradation further stimulate microbial activity, forming a synergistic degradation cycle of "starch-PLA-microorganisms," thereby achieving deep and efficient degradation. In addition, by controlling the PLA shell thickness and starch core particle size, the balance between the filler degradation rate and the material's mechanical properties can be customized to suit different application scenarios, which has profound research significance. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The degradation rate curves of the granular samples in Example 4 and the comparative example of the present invention are shown.

[0023] Figure 2 The degradation rate curves of the sheet samples in Example 4 and the comparative example of the present invention are shown. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1: Preparation of highly efficient degradable PP composite material, as detailed below:

[0026] (1) Preparation of core-shell composite degradable filler

[0027] Step A1: Mix diallylamine, γ-mercaptopropyltriethoxysilane, and anhydrous acetone under a dry atmosphere, using a stirring method of 300 mW / cm². 2 The reaction was carried out under ultraviolet irradiation and the photosensitizer was slowly added at room temperature and stirred for 15 hours. The feed ratio of diallylamine, γ-mercaptopropyltriethoxysilane, photosensitizer and anhydrous acetone was 0.1 mol: 0.2 mol: 0.16 g: 350 mL. The photosensitizer was benzoin dimethyl ether (DMPA). After that, the acetone was removed by evaporation to obtain the double-bridged agglomerate.

[0028] Step A2: Take the double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution for premixing. Adjust the pH of the premix to 4 with hydrochloric acid. Add starch and disperse ultrasonically. Then stir at 120 rpm for 2.5 h. The feed ratio of starch, double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution is 50 g: 3.6 g: 1.1 g: 220 mL. The mass fraction of tetrahydrofuran aqueous solution is 50%. Tween 80 is selected as the nonionic emulsifier. Centrifuge to remove the supernatant. Spray dry the bottom concentrate to obtain modified starch.

[0029] Step A3: Take modified starch, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide, premix them, then add L-lactide in chloroform solution and mix well. Purge with nitrogen for protection, heat to 150℃ and stir for 7h. Then reduce the pressure to 50Pa, heat to 210℃ and continue to react for 4h. The feed ratio of modified starch, L-lactide, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide is 50g:8.5g:0.18g:0.1g:150mL. Discharge, cool, wash and dry to obtain core-shell composite degradable filler.

[0030] (2) Preparation of composite materials

[0031] Ingredients: 39 wt% core-shell composite degradable filler, prepared in this embodiment; 3.5 wt% compatibilizer, selected from PO 1020 type maleic anhydride grafted polypropylene; 2.3 wt% lubricant, selected from 6108C type polypropylene wax; 0.15 wt% nucleating agent, selected from BT-5 type amide nucleating agent; 0.1 wt% antioxidant, selected from antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1; the remainder is PP resin, selected from K1003 type resin raw material.

[0032] Blending molding: PP resin, compatibilizer, lubricant, nucleating agent and antioxidant are premixed and fed into the main feed port of the extruder. Core-shell composite degradable filler is fed into the side feed port of the extruder. The temperature zones of the extruder barrel are controlled as follows: Zone 1 180℃, Zone 2 190℃, Zone 3 200℃, Zone 4 210℃, Zone 5 210℃, Zone 6 210℃, and die 220℃. The components are blended and extruded to obtain a high-efficiency degradable PP composite material.

[0033] Example 2: Preparation of highly efficient degradable PP composite material, as detailed below:

[0034] (1) Preparation of core-shell composite degradable filler

[0035] Step A1: Mix diallylamine, γ-mercaptopropyltriethoxysilane, and anhydrous acetone under a dry atmosphere, using a stirring method of 400 mW / cm². 2 The reaction was carried out under ultraviolet irradiation and the photosensitizer was slowly added at room temperature and stirred for 12 hours. The feed ratio of diallylamine, γ-mercaptopropyltriethoxysilane, photosensitizer and anhydrous acetone was 0.1 mol: 0.2 mol: 0.22 g: 400 mL. The photosensitizer was benzoin dimethyl ether. After that, the acetone was removed by evaporation to obtain the double-bridged agglomerate.

[0036] Step A2: Take the double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution for premixing. Adjust the pH of the premix to 3 with hydrochloric acid. Add starch and disperse ultrasonically. Then stir at 150 rpm for 2 hours. The feed ratio of starch, double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution is 50g:4.2g:1.5g:260mL. The mass fraction of tetrahydrofuran aqueous solution is 60%. Tween 80 is selected as the nonionic emulsifier. Centrifuge to remove the supernatant. Spray dry the bottom concentrate to obtain modified starch.

[0037] Step A3: Take modified starch, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide, premix them, then add L-lactide in chloroform solution and mix well. Purge with nitrogen and heat to 160℃ and stir for 6 hours. Then reduce the pressure to 50 Pa and heat to 220℃ to continue the reaction for 3.5 hours. The feed ratio of modified starch, L-lactide, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide is 50g:11g:0.24g:0.13g:200mL. Discharge, cool, wash and dry to obtain core-shell composite degradable filler.

[0038] (2) Preparation of composite materials

[0039] Ingredients: 46 wt% core-shell composite degradable filler, prepared in this embodiment; 4.2 wt% compatibilizer, selected from PO 1020 type maleic anhydride grafted polypropylene; 1.8 wt% lubricant, selected from 6108C type polypropylene wax; 0.12 wt% nucleating agent, selected from BT-5 type amide nucleating agent; 0.08 wt% antioxidant, selected from antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1, with the remainder being PP resin, selected from K1003 type resin raw material.

[0040] Blending molding: PP resin, compatibilizer, lubricant, nucleating agent and antioxidant are premixed and fed into the main feed port of the extruder. Core-shell composite degradable filler is fed into the side feed port of the extruder. The temperature zones of the extruder barrel are controlled as follows: Zone 1 170℃, Zone 2 180℃, Zone 3 190℃, Zone 4 200℃, Zone 5 200℃, Zone 6 200℃, and die 210℃. The components are blended and extruded to obtain a high-efficiency degradable PP composite material.

[0041] Example 3: Preparation of highly efficient degradable PP composite material, as detailed below:

[0042] (1) Preparation of core-shell composite degradable filler

[0043] Step A1: Mix diallylamine, γ-mercaptopropyltriethoxysilane, and anhydrous acetone under a dry atmosphere, using a stirring method of 350 mW / cm². 2 The reaction was carried out under ultraviolet irradiation and the photosensitizer was slowly added at room temperature and stirred for 14 hours. The feed ratio of diallylamine, γ-mercaptopropyltriethoxysilane, photosensitizer and anhydrous acetone was 0.1 mol: 0.2 mol: 0.18 g: 380 mL. The photosensitizer was benzoin dimethyl ether. After that, the acetone was removed by evaporation to obtain the double-bridged agglomerate.

[0044] Step A2: Take the double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution for premixing. Adjust the pH of the premix to 3 with hydrochloric acid. Add starch and disperse ultrasonically. Then stir at 150 rpm for 2.2 h. The feed ratio of starch, double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution is 50 g: 3.9 g: 1.3 g: 240 mL. The mass fraction of tetrahydrofuran aqueous solution is 50%. Tween 80 is selected as the nonionic emulsifier. Centrifuge to remove the supernatant. Spray dry the bottom concentrate to obtain modified starch.

[0045] Step A3: Take modified starch, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide, premix them, then add L-lactide in chloroform solution and mix well. Purge with nitrogen for protection, heat to 160℃ and stir for 6.2h. Then reduce the pressure to 50Pa, heat to 210℃ and continue the reaction for 4h. The feed ratio of modified starch, L-lactide, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide is 50g:10g:0.22g:0.1g:170mL. Discharge, cool, wash and dry to obtain core-shell composite degradable filler.

[0046] (2) Preparation of composite materials

[0047] Ingredients: 42 wt% core-shell composite degradable filler, prepared in this embodiment; 3.8 wt% compatibilizer, selected from PO 1020 type maleic anhydride grafted polypropylene; 2 wt% lubricant, selected from 6108C type polypropylene wax; 0.14 wt% nucleating agent, selected from BT-5 type amide nucleating agent; 0.09 wt% antioxidant, selected from antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1; the remainder is PP resin, selected from K1003 type resin raw material.

[0048] Blending molding: PP resin, compatibilizer, lubricant, nucleating agent and antioxidant are premixed and fed into the main feed port of the extruder. Core-shell composite degradable filler is fed into the side feed port of the extruder. The temperature zones of the extruder barrel are controlled as follows: Zone 1 180℃, Zone 2 190℃, Zone 3 200℃, Zone 4 210℃, Zone 5 210℃, Zone 6 210℃, and die 220℃. The components are blended and extruded to obtain a high-efficiency degradable PP composite material.

[0049] Example 4: Preparation of highly efficient degradable PP composite material, as detailed below:

[0050] (1) Preparation of core-shell composite degradable filler

[0051] Step A1: Mix diallylamine, γ-mercaptopropyltriethoxysilane, and anhydrous acetone under a dry atmosphere, using a stirring method of 400 mW / cm². 2The mixture was subjected to ultraviolet irradiation, and the photosensitizer was slowly added and stirred at room temperature for 13 hours. The feed ratio of diallylamine, γ-mercaptopropyltriethoxysilane, photosensitizer and anhydrous acetone was 0.1 mol: 0.2 mol: 0.2 g: 350 mL. The photosensitizer was benzoin dimethyl ether. After that, the acetone was evaporated to obtain the double-bridged agglomerate.

[0052] Step A2: Take the double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution for premixing. Adjust the pH of the premix to 3 with hydrochloric acid. Add starch and disperse ultrasonically. Then stir at 150 rpm for 2 hours. The feed ratio of starch, double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution is 50g:4.2g:1.3g:250mL. The mass fraction of tetrahydrofuran aqueous solution is 60%. Tween 80 is selected as the nonionic emulsifier. Centrifuge to remove the supernatant. Spray dry the bottom concentrate to obtain modified starch.

[0053] Step A3: Take modified starch, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide, premix them, then add L-lactide in chloroform solution and mix well. Purge with nitrogen for protection, heat to 155℃ and stir for 7h. Then reduce the pressure to 50Pa, heat to 210℃ and continue the reaction for 4h. The feed ratio of modified starch, L-lactide, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide is 50g:9.5g:0.22g:0.12g:180mL. Discharge, cool, wash and dry to obtain core-shell composite degradable filler.

[0054] (2) Preparation of composite materials

[0055] Ingredients: 44 wt% core-shell composite degradable filler, prepared in this embodiment; 4 wt% compatibilizer, selected from PO 1020 type maleic anhydride grafted polypropylene; 1.9 wt% lubricant, selected from 6108C type polypropylene wax; 0.13 wt% nucleating agent, selected from BT-5 type amide nucleating agent; 0.09 wt% antioxidant, selected from antioxidant 1010 and antioxidant 168 in a weight ratio of 2:1, with the remainder being PP resin, selected from K1003 type resin raw material.

[0056] Blending molding: PP resin, compatibilizer, lubricant, nucleating agent and antioxidant are premixed and fed into the main feed port of the extruder. Core-shell composite degradable filler is fed into the side feed port of the extruder. The temperature zones of the extruder barrel are controlled as follows: Zone 1 180℃, Zone 2 180℃, Zone 3 190℃, Zone 4 200℃, Zone 5 200℃, Zone 6 210℃, and the die head 220℃. The components are blended and extruded to obtain a high-efficiency degradable PP composite material.

[0057] In the comparative example, referring to Example 4, the core-shell composite degradable filler was replaced with 40 wt% starch and 4 wt% polylactic acid micro powder, and the rest of the implementation process was exactly the same.

[0058] Samples were taken from the composite material prepared above, and tensile properties were tested according to GB / T 1040.2-2018 standard, and impact properties were tested according to GB / T 1843-2008 standard; the specific test results are shown in Table 1:

[0059] Table 1

[0060] Tensile strength / MPa Elongation at break / % <![CDATA[Impact strength / kJ·m -2 > Example 1 20.55 81.46 9.24 Example 2 17.14 89.53 11.65 Example 3 19.09 84.27 10.82 Example 4 18.31 86.50 10.57 Comparative Example 11.63 52.86 8.03

[0061] As can be seen from the test data in Table 1, the PP composite material prepared in the example has excellent strength and toughness, and its mechanical properties are significantly improved compared with the direct use of starch and polylactic acid blends.

[0062] Flake-shaped samples with dimensions of 100×50×10mm were prepared from the above composite material. These samples were then crushed into granular samples that passed through a 2mm sieve using a pulverizer. Soil degradation tests were conducted using humus soil from the same garden as the samples. The degradation rate was characterized by calculating the weight loss rate using the weighing method. Figure 1-Figure 2 The degradation rate curves of Example 4 and the comparative example are shown below;

[0063] Depend on Figure 1-Figure 2 The test results show that the degradation rate of the sheet-like PP composite material in Example 4 is slow and the degradation rate after 180 days is low; the degradation rate of the crushed particles is significantly improved, similar to that of the comparative example, and the degradation rate after 180 days exceeds that of the comparative example, demonstrating deep and efficient degradation characteristics.

[0064] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0065] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A highly efficient degradable PP composite material, characterized in that, The specific components are: 39-46 wt% core-shell composite degradable filler, 3.5-4.2 wt% compatibilizer, 1.8-2.3 wt% lubricant, 0.12-0.15 wt% nucleating agent and 0.08-0.1 wt% antioxidant, with the balance being PP resin; The core-shell composite degradable filler is prepared by the following method: Step A1: Mix diallylamine, γ-mercaptopropyltriethoxysilane, and anhydrous acetone under a dry atmosphere, using a stirring pressure of 300-400 mW / cm². 2 After UV irradiation, photosensitizer was slowly added at room temperature and stirred for 12-15 hours. Then, acetone was removed by evaporation to obtain the double-bridged agglomerant. Step A2: Premix the double-bridge agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution, adjust the pH of the premix to 3-4 with hydrochloric acid, add starch and ultrasonically disperse, then stir at 120-150 rpm for 2-2.5 h, centrifuge to remove the supernatant, spray dry the bottom concentrate to obtain modified starch; Step A3: Premix modified starch, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide, then add chloroform solution of L-lactide and mix well. Under nitrogen protection, heat to 150-160℃ and stir for 6-7 hours. Then reduce the pressure to 50 Pa and heat to 210-220℃ to continue the reaction for 3.5-4 hours. Discharge, cool, wash and dry to obtain core-shell composite degradable filler.

2. The highly efficient degradable PP composite material according to claim 1, characterized in that, The feed ratio of diallylamine, γ-mercaptopropyltriethoxysilane, photosensitizer and anhydrous acetone is 0.1mol:0.2mol:0.16-0.22g:350-400mL.

3. The highly efficient degradable PP composite material according to claim 2, characterized in that, The feeding ratio of starch, double-bridged agglomerator, nonionic emulsifier and tetrahydrofuran aqueous solution is 50g: 3.6-4.2g: 1.1-1.5g: 220-260mL.

4. The highly efficient degradable PP composite material according to claim 3, characterized in that, The feed ratio of modified starch, L-lactide, stannous chloride, p-toluenesulfonic acid and dimethyl sulfoxide is 50g: 8.5-11g: 0.18-0.24g: 0.1-0.13g: 150-200mL.

5. The highly efficient degradable PP composite material according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polypropylene.

6. The highly efficient degradable PP composite material according to claim 1, characterized in that, The nucleating agent is an amide nucleating agent.

7. A method for preparing a highly efficient degradable PP composite material according to any one of claims 1-6, characterized in that, Specifically, PP resin, compatibilizer, lubricant, nucleating agent and antioxidant are premixed and fed into the main feed port of the extruder, and the core-shell composite degradable filler is fed into the side feed port of the extruder. The mixture is then co-extruded to obtain a highly efficient degradable PP composite material.

8. The method for preparing a highly efficient degradable PP composite material according to claim 7, characterized in that, The extruder barrel temperature zones are set as follows: Zone 1 170-180℃, Zone 2 180-190℃, Zone 3 190-200℃, Zone 4 200-210℃, Zone 5 200-210℃, Zone 6 200-210℃, and Die head 210-220℃.

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