Multifunctional additive based on double grafting, preparation method and application in sheet materials

Abstract

The invention discloses a multifunctional auxiliary agent based on double grafting, a preparation method and application in a sheet material, and relates to the technical field of polymer material modification. The method for preparing the auxiliary agent comprises the following steps: S1: dissolving 4,4-dicarboxylic acid diphenyl ether in N,N-dimethylformamide, and adding chloroacetamide and triethylamine to the solution; S2: adding glycerol triglycidyl ether and zinc acetylacetonate to carry out a reaction; S3: adding (3,4-epoxycyclohexyl) methyl acrylate after the reaction and continuing the reaction to obtain a grafting auxiliary agent precursor; S4: mixing PBAT, an initiator and the grafting auxiliary agent precursor, and then melt-extruding to obtain PBAT-g-TCOE; S5: mixing PBAT-g-TCOE, an initiator and PBS, and then melt-extruding to obtain the multifunctional auxiliary agent. The additive synthesis process of the present invention is simple, can overcome the problems of low nucleation efficiency and poor compatibility with PLA / PBAT of existing additives, and can significantly improve the compatibility between PLA and PBAT, thereby enhancing the mechanical and thermal properties of the PLA / PBAT composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material modification, in particular to a multifunctional auxiliary agent based on double grafting, a preparation method and application of the auxiliary agent in sheet materials. Background Art

[0002] Polylactic acid (PLA), one of the most promising biodegradable materials, has already been used in disposable tableware and packaging. It also has numerous applications in the medical field, such as disposable infusion devices, surgical sutures, and tissue repair materials. However, PLA suffers from drawbacks such as poor toughness, easy bending and deformation, weak impact and tear resistance, slow crystallization, and poor thermal properties, which limit its application. Polybutylene adipate / terephthalate (PBAT), a biodegradable plastic, offers high flexibility, good ductility, and high processing stability, and its blending with PLA can complement its performance. Therefore, PBAT can be used to toughen PLA. However, PLA and PBAT have poor compatibility. When the PBAT content exceeds 5%, the PLA / PBAT blend is prone to phase separation, which degrades the performance of the blend. Therefore, addressing the compatibility of PLA and PBAT is crucial.

[0003] Currently, the main approaches to address toughening, nucleation, and compatibilization in PLA / PBAT systems include plasticizing and modifying the PLA / PBAT, as well as adding nucleating and compatibilizing agents. For example, the plasticizer acetylated tributyl citrate (ATBC) plays a key role in PLA / PBAT composites, particularly in improving their mechanical properties and processing performance. Adding ATBC and epoxidized soybean oil (ESO) to PLA / PBAT composites prepared by melt blending can enhance the composite's tensile strength and elongation at break while maintaining good biodegradability. However, these plasticizers have drawbacks such as high dosage, easy migration, and adhesion to machine surfaces, resulting in poor long-term performance and a reduction in mechanical properties. Alternatively, inorganic nucleating agents are inexpensive and readily available. Adding these nucleating agents to PLA / PBAT composites can accelerate the crystallization rate of PLA and PBAT, increase the density of crystal nuclei, and thus enhance crystallinity. However, inorganic nucleating agents have poor compatibility with PLA / PBAT and low nucleation efficiency, and their excessive use can affect the appearance, quality, and performance of finished products. For example, epoxy and isocyanate compatibilizers can be added to PLA / PBAT systems. Compared to epoxy chain extenders (ADRs), isocyanates are highly toxic, limiting their application. ADRs, on the other hand, have 3-9 epoxy functional groups on their backbones, exhibit low toxicity, and offer excellent compatibilization. However, ADR compatibilizers are expensive. Therefore, there is an urgent need to develop additives that can significantly improve the interfacial compatibility and crystallization properties of PLA and PBAT, and enhance the mechanical and thermal properties of PLA / PBAT composites. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a multifunctional additive based on double grafting, a preparation method and its application in sheet materials. The synthesis process of the additive is simple, which can overcome the problems of low nucleation efficiency and poor compatibility with PLA / PBAT of existing additives, and can significantly improve the compatibility between PLA and PBAT, thereby enhancing the mechanical and thermal properties of PLA / PBAT composites.

[0005] The preparation method of the multifunctional additive based on double grafting proposed in the present invention comprises the following steps:

[0006] S1: reacting 4,4-dicarboxylic acid diphenyl ether, chloroacetamide and triethylamine in N,N-dimethylformamide;

[0007] S2: adding glycerol triglycidyl ether and zinc acetylacetonate to the solution after the reaction in S1 to carry out the reaction;

[0008] S3: adding (3,4-epoxycyclohexyl) methyl acrylate to the solution after the reaction in S2 to react and obtain a grafting aid precursor;

[0009] S4: melt-extruding poly(butylene adipate / terephthalate), initiator and grafting aid precursor;

[0010] S5: The melt-extruded product of S4 is mixed with an initiator and polybutylene succinate and then melt-extruded to obtain a multifunctional additive.

[0011] Preferably, the mass ratio of chloroacetamide, triethylamine, 4,4-dicarboxylic acid diphenyl ether, glycerol triglycidyl ether, (3,4-epoxycyclohexyl) methyl acrylate and zinc acetylacetonate is 1:1-1.5:1-2:1-1.5:1.5-2.5:0.05-0.3.

[0012] Preferably, the reaction conditions in S1 are: temperature 70-110° C., time 3-10 h.

[0013] Preferably, the reaction conditions in S2 and S3 are: temperature 50-100° C., time 4-6 h.

[0014] Preferably, the mass ratio of poly(butylene adipate / terephthalate), initiator and grafting aid precursor in S4 is 10:0.01-0.5:0.05-1; the melt extrusion conditions are: screw speed of 200-400 r / min, feeding rate of 3-8 r / min, and extrusion temperature zone set to 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150 ℃.

[0015] Preferably, the mass ratio of polybutylene succinate, initiator and melt extruded product of S4 in S5 is 2-8:0.01-0.5:10; the melt extrusion conditions are: screw speed of 200-400 r / min, feeding rate of 3-8 r / min, and extrusion temperature zone set to 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150 ℃.

[0016] Preferably, the initiator in S4 and S5 is one or more of diisopropyl benzene peroxide, benzoyl peroxide, tert-butyl isopropyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3 and di(tert-butylperoxyisopropyl)benzene.

[0017] The present invention provides a multifunctional auxiliary agent based on double grafting, which is prepared by adopting the above-mentioned preparation method.

[0018] The present invention provides a method for preparing a composite material, which comprises the following steps: mixing polyadipate / butylene terephthalate, polylactic acid and the above-mentioned multifunctional additive, and then melt-extruding the mixture to prepare the composite material.

[0019] Preferably, the mass ratio of polylactic acid, polybutylene adipate / terephthalate and multifunctional additive is 70-90:10-20:0.1-3; the melt extrusion conditions are: screw speed of 200-300 r / min, feeding rate of 3-6 r / min, and extrusion temperature zones are set to 135, 140, 145, 150, 155, 160, 165, 165, 165, 160, 155 ℃.

[0020] The present invention proposes the application of the above composite material in sheet materials.

[0021] Beneficial technical effects of the present invention:

[0022] The present invention proposes a nucleophilic substitution-epoxy ring-opening-double grafting method, using chloroacetamide, 4,4-dicarboxylic acid diphenyl ether, glycerol triglycidyl ether, 3,4-epoxycyclohexyl methyl acrylate, PBAT, and PBS as raw materials to prepare a multifunctional auxiliary agent; the substance is grafted with two tough polyesters and simultaneously has amide, hydroxyl, double bonds, and epoxy functional groups, belonging to an integrated structure, which is significantly different from conventional PBAT or PLA grafts; the substance can not only take advantage of the high toughness and compatibility of the polyesters at both ends, but also can produce multiple hydrogen bonds and chemical bond cross-linking networks, so it can simultaneously exhibit multiple functions such as nucleation, volume expansion, and toughening in the PLA / PBAT system, thereby enhancing the mechanical and thermal properties of the PLA / PBAT composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FTIR comparison chart of TCOE-1, PBAT, PBAT-g-TCOE-1 and PBAT-g-TCOE-g-PBS-1 proposed in the present invention;

[0024] Figure 2 Comparison of the crystallization / melting curves of PLA / PBAT-1 and PLA / PBAT / PBAT-g-TCOE-g-PBS-1 proposed in the present invention; (a) is the first cooling crystallization process, and (b) is the second heating melting process;

[0025] Figure 3 Schematic diagram of the synthesis mechanism of PBAT-g-TCOE-g-PBS proposed in the present invention;

[0026] Figure 4 Schematic diagram of the action mechanism of PLA / PBAT / PBAT-g-TCOE-g-PBS proposed in the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further explained below with reference to specific embodiments.

[0028] The polylactic acid (PLA), polybutylene adipate / terephthalate (PBAT), chloroacetamide (CC), glycerol triglycidyl ether (TPEG), 4,4-dicarboxylic acid diphenyl ether (OBA), N,N-dimethylformamide (DMF), triethylamine (TEA), (3,4-epoxycyclohexyl) methyl acrylate (EMA), zinc acetylacetonate, polybutylene succinate (PBS), etc. in the embodiments of the present invention are all commercially available.

[0029] Example 1

[0030] First, 5 g of OBA was weighed and added to 750 g of DMF to form a solution. Then, the above solution was transferred to a three-necked flask, and 3.9 g of TEA was added dropwise to obtain a mixed solution. Next, 3.6 g of CC was added to the above mixed solution, and the mixture was stirred at 85 °C for 8 h. The resulting solution was recorded as CO-1.

[0031] Weigh 5 g of TPEG, pipette it with a rubber tip, and add it dropwise to solution CO-1 at a rate of 1 drop / second. Then, add 0.6 g of zinc acetylacetonate to solution CO-1, and stir the reaction at 70 °C for 6 h. The resulting solution is recorded as TCO-1.

[0032] Weigh 6 g of EMA, pipette it with a rubber tip, and add it dropwise to the TCO-1 solution at a rate of 1 drop / s. Then, stir and react at 75 °C for 5 h. The resulting solution is designated as TCOE-1.

[0033] After the solution TCOE-1 is cooled, it is transferred to a single-necked flask and rotary evaporated at 160°C. After rotary evaporation until no liquid drips out, the remaining portion in the single-necked flask is taken out and dried in a 100°C oven for 4 h. The dried solid is then washed with anhydrous ethanol for more than three times. After washing, the obtained solid is dried in an oven at 100°C for 8 h to obtain a grafting aid precursor.

[0034] Weigh 120 g of PBAT, 3 g of diisopropylbenzene peroxide and 10 g of grafting aid precursor into a high-speed mixer and mix at 200 r / min for 10 min to obtain a solid mixture.

[0035] The above 133 g solid mixture was placed in a twin-screw extruder, the screw speed was set to 200 r / min, the feeding rate was set to 6 r / min, the extrusion temperature zone was set to 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150°C, and the mixture was melt-extruded, cooled, and dried at 80°C for 12 h to obtain the product, which was recorded as PBAT-g-TCOE-1.

[0036] 120 g PBS, 3 g dicumyl peroxide and 60 g PBAT-g-TCOE-1 were weighed and put into a high-speed mixer and mixed at 200 r / min for 10 min. The mixture was then put into a twin-screw extruder, the screw speed was set to 200 r / min, the feeding rate was 6 r / min, the extrusion temperature zone was set to 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150 ℃, after melt extrusion, cooling, and drying at 80 ℃ for 12 h, the multifunctional additive was recorded as PBAT-g-TCOE-g-PBS-1.

[0037] 160 g PBAT, 800 g PLA and 10 g multifunctional additive PBAT-g-TCOE-g-PBS-1 were weighed and placed in a high-speed mixer and mixed at a speed of 500 r / min for 20 min to obtain a mixture; then, the mixture was melt-extruded, the screw speed was set to 200 r / min, the feeding rate was set to 6 r / min, and the extrusion temperature zone was set to 135, 140, 145, 150, 155, 160, 165, 165, 165, 160, 155 ℃ to obtain a composite material recorded as PLA / PBAT / PBAT-g-TCOE-g-PBS-1.

[0038] Example 2

[0039] Weigh 5.5 g of TPEG, pipette it with a rubber tip, and add it dropwise to solution CO-1 at a rate of 1 drop / second. Then, add 0.6 g of zinc acetylacetonate to solution CO-1, and stir the reaction at 70 °C for 6 h. The resulting solution is recorded as TCO-2.

[0040] Weigh 6 g of EMA, pipette it with a rubber tip, and add it dropwise to the TCO-2 solution at a rate of 1 drop / s. Then, stir and react at 75 °C for 5 h. The resulting solution is recorded as TCOE-2.

[0041] After the solution TCOE-2 is cooled, it is transferred to a single-necked flask and rotary evaporated at 160°C. After rotary evaporation until no liquid drips out, the remaining portion in the single-necked flask is taken out and dried in a 100°C oven for 4 h. The dried solid is then washed with anhydrous ethanol for more than three times. After washing, the obtained solid is dried in an oven at 100°C for 8 h to obtain a grafting aid precursor.

[0042] Weigh 120 g of PBAT, 3 g of diisopropylbenzene peroxide and 10 g of grafting aid precursor into a high-speed mixer and mix at 200 r / min for 10 min to obtain a solid mixture.

[0043] The above 133 g solid mixture was placed in a twin-screw extruder, the screw speed was set to 200 r / min, the feeding rate was set to 6 r / min, the extrusion temperature zone was set to 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150°C, and the mixture was melt-extruded, cooled, and dried at 80°C for 12 h to obtain the product, which was recorded as PBAT-g-TCOE-2.

[0044] 120 g PBS, 3 g dicumyl peroxide and 60 g PBAT-g-TCOE-2 were weighed and put into a high-speed mixer and mixed at 200 r / min for 10 min. The mixture was then put into a twin-screw extruder, the screw speed was set to 200 r / min, the feeding rate was 6 r / min, the extrusion temperature zone was set to 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150 ℃, after melt extrusion, cooling, and drying at 80 ℃ for 12 h, the multifunctional additive was recorded as PBAT-g-TCOE-g-PBS-2.

[0045] 160 g PBAT, 800 g PLA and 10 g multifunctional additive PBAT-g-TCOE-g-PBS-2 were weighed and placed in a high-speed mixer and mixed at a speed of 500 r / min for 20 min to obtain a mixture; then, the mixture was melt-extruded, the screw speed was set to 200 r / min, the feeding rate was set to 6 r / min, and the extrusion temperature zone was set to 135, 140, 145, 150, 155, 160, 165, 165, 165, 165, 160, and 155 ℃ to obtain a composite material recorded as PLA / PBAT / PBAT-g-TCOE-gPBS-2.

[0046] Example 3

[0047] 4.5 g of TPEG was weighed and added to solution CO-1 using a rubber-tipped dropper at a rate of 1 drop / s. Next, 0.6 g of zinc acetylacetonate was added to solution CO-1 and the mixture was stirred at 70 °C for 6 h to obtain a solution designated as TCO-3.

[0048] Weigh 6 g of EMA, pipette it with a rubber tip, and add it dropwise to the TCO-3 solution at a rate of 1 drop / s. Then, stir and react at 75 °C for 5 h. The resulting solution is designated as TCOE-3.

[0049] After the solution TCOE-3 is cooled, it is transferred to a single-necked flask and rotary evaporated at 160°C. After rotary evaporation until no liquid drips out, the remaining portion in the single-necked flask is taken out and dried in a 100°C oven for 4 h. The dried solid is then washed with anhydrous ethanol for more than three times. After washing, the obtained solid is dried in an oven at 100°C for 8 h to obtain a grafting aid precursor.

[0050] Weigh 120 g of PBAT, 3 g of diisopropylbenzene peroxide and 10 g of grafting aid precursor into a high-speed mixer and mix at 200 r / min for 10 min to obtain a solid mixture.

[0051] The above 133 g solid mixture was placed in a twin-screw extruder, the screw speed was set to 200 r / min, the feeding rate was set to 6 r / min, the extrusion temperature zone was set to 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150°C, and the mixture was melt-extruded, cooled, and dried at 80°C for 12 h to obtain the product, which was recorded as PBAT-g-TCOE-3.

[0052] 120 g PBS, 3 g dicumyl peroxide and 60 g PBAT-g-TCOE-3 were weighed and put into a high-speed mixer and mixed at 200 r / min for 10 min. The mixture was then put into a twin-screw extruder, the screw speed was set to 200 r / min, the feeding rate was 6 r / min, the extrusion temperature zone was set to 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150 ℃, and after melt extrusion, cooling and drying at 80 ℃ for 12 h, the multifunctional additive was recorded as PBAT-g-TCOE-g-PBS-3.

[0053] 160 g PBAT, 800 g PLA and 10 g multifunctional additive PBAT-g-TCOE-g-PBS-3 were weighed and placed in a high-speed mixer and mixed at a speed of 500 r / min for 20 min to obtain a mixture; then, the mixture was melt-extruded, the screw speed was set to 200 r / min, the feeding rate was set to 6 r / min, and the extrusion temperature zone was set to 135, 140, 145, 150, 155, 160, 165, 165, 165, 165, 160, and 155 ℃ to obtain a composite material recorded as PLA / PBAT / PBAT-g-TCOE-g-PBS-3.

[0054] Comparative Example 1

[0055] 160 g PBAT and 800 g PLA were weighed and placed in a high-speed mixer and mixed at a speed of 500 r / min for 20 min to obtain a mixture; the mixture was melt-extruded, the screw speed was set to 200 r / min, the feeding rate was set to 6 r / min, and the extrusion temperature zone was set to 135, 140, 145, 150, 155, 160, 165, 165, 165, 160, 155 ℃ to obtain a composite material recorded as PLA / PBAT-1.

[0056] Comparative Example 2

[0057] 160 g PBAT, 800 g PLA and 10 g PBAT-g-TCOE-1 were weighed and placed in a high-speed mixer and mixed at a speed of 500 r / min for 20 min to obtain a mixture; then, the mixture was melt-extruded, the screw speed was set to 200 r / min, the feeding rate was set to 6 r / min, and the extrusion temperature zone was set to 135, 140, 145, 150, 155, 160, 165, 165, 165, 160, 155 ℃ to obtain a composite material recorded as PLA / PBAT / PBAT-g-TCOE-1.

[0058] The present invention conducted mechanical property tests on pure PLA, samples prepared in Examples 1-3 and Comparative Examples 1-2, and the results are shown in Table 1.

[0059] Table 1 Mechanical properties test

[0060]

[0061] As shown in Table 1, the pure PLA sample is hard and brittle. After adding PBAT, the tensile and flexural strengths decrease, but the elongation at break and impact strength increase. Overall, the mechanical properties of PLA / PBAT / PBAT-g-TCOE-g-PBS are better than those of PLA / PBAT samples. For example, the sample in Example 1 has a tensile strength of 46.82 MPa, an elongation at break of 68%, a flexural strength of 47.68 MPa, an impact strength of 15.27 MPa, and a flexural modulus of 1423 MPa. The reason for this phenomenon is that the interfacial compatibility between PLA and PBAT is poor, and direct blending will reduce the mechanical properties. However, after adding PBAT-g-TCOE-g-PBS, the mechanical properties of the PLA / PBAT sample are significantly improved. This is because PBAT-g-TCOE-g-PBS has good compatibility with PLA and PBAT, and can further enhance the compatibility and crystallization properties of PLA and PBAT by building a hydrogen bond and chemical bond cross-linking network, thereby improving the mechanical properties of the PLA / PBAT composite material. It can also be seen from Examples 1-3 and Comparative Example 2 that when the mass ratio of TPEG, CC, OBA and EMA is 5:3.6:5:6, the mechanical properties of the sample are the best, and the double-grafted PBAT-g-TCOE-g-PBS adjuvant is better than PBAT-g-TCOE.

[0062] The present invention performs FTIR test on PBAT, TCOE-1, PBAT-g-TCOE-1 and PBAT-g-TCOE-PBS-1. The results are as follows: Figure 1 As shown. Figure 1 It can be seen that in the FTIR spectrum of TCOE-1, 1563 cm -1 At the same time, compared with the FTIR spectrum of PBAT, the spectrum of PBAT-g-TCOE-1 shows the following significant features: at 956 cm -1 is the symmetrical CO bond stretching vibration absorption peak of the epoxy group, 1258 cm -1 The peak is the asymmetric CO bond stretching vibration absorption peak of the epoxy group, 3393 cm -1 The absorption peak is the stretching vibration peak of NH. Based on the changes in the above spectral characteristics, it can be seen that TCOE-1 has been successfully grafted onto PBAT. In addition, compared with the FTIR infrared spectrum of PBAT-g-TCOE-1, the 727cm -1 The CH bending vibration peak at was enhanced, and no new absorption peak was generated, which shows that PBS has been successfully grafted onto PBAT-g-TCOE-1.

[0063] The present invention conducted differential thermal scanning tests on PLA / PBAT-1 and PLA / PBAT / PBAT-g-TCOE-g-PBS-1, and the results were as follows: Figure 2 As shown in Figure 2, (a) is the first cooling crystallization process, and (b) is the second heating melting process. The thermodynamic parameters of the samples are shown in Table 2.

[0064] Table 2 Thermodynamic parameters of samples

[0065]

[0066] Depend on Figure 2 (a) and Table 2 show that the crystallization peak of PLA / PBAT-1 is weak. After adding PBAT-g-TCOE-g-PBS-1 to the system, its crystallization temperature increases, and the crystallization peak strengthens and moves closer to the high temperature zone. This is because during the cooling process, PBAT-g-TCOE-g-PBS-1 can provide crystal nuclei at higher temperatures and induce PLA and PBAT molecular chains to attach to them and grow, thus playing the role of a nucleating agent. Figure 2 It can also be seen from (b) and Table 2 that when PBAT-g-TCOE-g-PBS-1 is added to the system, the melting temperature increases, indicating that the addition of PBAT-g-TCOE-g-PBS-1 can enhance the thermal properties of PLA / PBAT materials.

[0067] Figure 3 Schematic diagram of the synthesis mechanism of PBAT-g-TCOE-g-PBS proposed in the present invention. Figure 3 As shown, the present invention first uses OBA and CC to undergo a nucleophilic substitution reaction under the catalysis of TEA to obtain CO; then TPEG and EMA are added to CO in sequence, and an epoxy group ring-opening reaction is carried out under the action of a catalyst zinc acetylacetonate to obtain a grafting aid precursor; finally, the grafting aid precursor is subjected to a double grafting reaction with PBAT and PBS under the action of an initiator to obtain PBAT-g-TCOE-g-PBS.

[0068] Figure 4 This is a schematic diagram of the mechanism of action of PLA / PBAT / PBAT-g-TCOE-g-PBS proposed in the present invention. PBAT-g-TCOE-g-PBS is grafted with two polyesters. PBAT and PBS have strong toughness and good compatibility, so PBAT-g-TCOE-g-PBS can significantly enhance the toughness of PLA / PBAT composites. Figure 4As shown, the NH and OH groups in the PBAT-g-TCOE-g-PBS molecules form hydrogen bonds with oxygen atoms on PLA and PBAT, enhancing the interaction between PBAT-g-TCOE-PBS and PLA and PBAT. Therefore, during the cooling crystallization process of the PLA / PBAT / PBAT-g-TCOE-g-PBS-1 sample, PBAT-g-TCOE-g-PBS-1 can provide crystal nuclei at higher temperatures and, through hydrogen bonding, induce PLA and PBAT molecular chains to adhere tightly to it and grow, thereby promoting crystallization. Furthermore, PBAT-g-TCOE-g-PBS molecules have double bonds on their surfaces, and during melt blending with PLA and PBAT, the epoxy functional groups in the PBAT-g-TCOE-g-PBS molecules simultaneously undergo ring-opening reactions with the terminal groups of PLA and PBAT, thereby improving the compatibility of PLA and PBAT.

[0069] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application. The scope of the present application is defined by the appended claims and their equivalents, and all should be included in the scope of protection of the present application.

Claims

1. A method for preparing a multifunctional additive based on double grafting, characterized in that: The steps are as follows: S1: reacting 4,4-dicarboxylic acid diphenyl ether, chloroacetamide and triethylamine in N,N-dimethylformamide; S2: adding glycerol triglycidyl ether and zinc acetylacetonate to the solution after the reaction in S1 to carry out the reaction; S3: adding (3,4-epoxycyclohexyl) methyl acrylate to the solution after the reaction in S2 to react and obtain a grafting aid precursor; S4: melt-extruding poly(butylene adipate / terephthalate), initiator and grafting aid precursor; S5: mixing the melt-extruded product of S4 with an initiator and polybutylene succinate and then melt-extruding the mixture to obtain a multifunctional additive; The mass ratio of poly(butylene adipate / terephthalate), initiator and grafting aid precursor in S4 is 10:0.01-0.5:0.05-1; The mass ratio of polybutylene succinate, initiator and melt extrusion product of S4 in S5 is 2-8:0.01-0.5:

10.

2. The method for preparing a multifunctional auxiliary agent based on double grafting according to claim 1, characterized in that: The mass ratio of chloroacetamide, triethylamine, 4,4-dicarboxylic acid diphenyl ether, glycerol triglycidyl ether, (3,4-epoxycyclohexyl) methyl acrylate and zinc acetylacetonate is 1:1-1.5:1-2:1-1.5:1.5-2.5:0.05-0.

3.

3. The method for preparing a multifunctional additive based on double grafting according to claim 1, characterized in that: The reaction conditions in S1 are: temperature 70-110 °C, time 3-10 h; the reaction conditions in S2 and S3 are: temperature 50-100 °C, time 4-6 h.

4. The method for preparing a multifunctional additive based on double grafting according to claim 1, characterized in that: The conditions for melt extrusion in S4 were as follows: screw speed of 200-400 r / min, feeding rate of 3-8 r / min, and extrusion temperature zones of 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150 °C.

5. The method for preparing a multifunctional additive based on double grafting according to claim 1, characterized in that: The conditions for melt extrusion in S5 were as follows: screw speed of 200-400 r / min, feeding rate of 3-8 r / min, and extrusion temperature zones of 145, 145, 145, 150, 150, 150, 155, 155, 155, 150, 150 °C.

6. The method for preparing a multifunctional additive based on double grafting according to claim 1, characterized in that: The initiator in S4 and S5 is one or more of diisopropyl benzene peroxide, benzoyl peroxide, tert-butyl isopropyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3 and di(tert-butylperoxyisopropyl)benzene.

7. A multifunctional additive based on double grafting, characterized in that: The method is prepared according to any one of claims 1 to 6.

8. A method for preparing a composite material, characterized in that: The method comprises the following steps: mixing polyadipate / butylene terephthalate, polylactic acid and the multifunctional auxiliary agent according to claim 7, and then melt-extruding the mixture to prepare a composite material.

9. The method for preparing a composite material according to claim 8, characterized in that: The mass ratio of polylactic acid, polybutylene adipate / terephthalate and multifunctional additive is 70-90:10-20:0.1-3; the melt extrusion conditions are: screw speed of 200-300 r / min, feeding rate of 3-6 r / min, and extrusion temperature zones set to 135, 140, 145, 150, 155, 160, 165, 165, 165, 160, 155 ℃.

10. Use of the composite material prepared by the preparation method according to claim 8 or 9 in sheet materials.

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