Modified PBAT material resistant to migration and precipitation and preparation method thereof

Abstract

The invention provides a migration-resistant and low-precipitation degradable PBAT modified material and a preparation method thereof. The modified PBAT material is prepared from the following raw materials: PBAT resin, PLA resin, modified starch and a slipping agent. The preparation method comprises the following steps: firstly, modifying starch through a self-made macromolecular polyester plasticizer, and then carrying out melt extrusion granulation on the modified starch, matrix resin and an auxiliary agent to prepare the modified PBAT material. The self-made macromolecular polyester plasticizer has the advantages that firstly, the feeding difficulty problems of caking, bridging and the like after the starch is in contact with the micromolecular liquid plasticizer in the processing process are effectively avoided; secondly, due to the large molecular weight and the cage structure, volatilization resistance is quite high in the material processing and final using process, and mobility and leaching performance are greatly improved; and thirdly, due to the large free volume, more free motion space is provided for molecular chains, and the tensile property of the material is improved.

Description

Technical Field

[0001] The present invention belongs to the field of degradable plastics, and particularly relates to a degradable PBAT modified material with resistance to migration and low precipitation, and a preparation method thereof. Background Art

[0002] In recent years, fully biodegradable materials (such as PLA, PBAT, etc.) have become an important way to solve the white pollution of traditional plastics because they can be completely decomposed by microorganisms in the natural environment. There are more and more products such as supermarket shopping bags, garbage bags, milk tea bags, etc. produced from degradable materials on the market. However, compared with traditional PE bags, the film bags made of degradable materials are expensive, and the products have problems such as precipitation, stickiness, and poor mechanical properties. The product iteration is fast, and the product performance has not been widely verified, so the penetration rate has not increased explosively.

[0003] Cost reduction and modification of degradable materials are important means to promote degradable products. Starch has a low cost, is green and environmentally friendly, and can be completely biodegradable, so it is widely used in the modification of PBAT materials. A large number of hydroxyl groups in the starch molecular structure result in strong intermolecular forces of starch molecules, which leads to large starch particle sizes and difficult dispersion. The traditional method is to add small molecule alcohols such as glycerol and sorbitol as plasticizers to plasticize the original starch. However, in fact, the plasticization process of starch is difficult, and the problems of precipitation and stickiness of the modified PBAT products still cannot be effectively improved.

[0004] Patent CN114957933B discloses a starch-based biodegradable PBAT modified material and a preparation method thereof, which solves the starch plasticization problem by preparing silicone microspheres to encapsulate glycerol plasticizer. However, in fact, the preparation process of the silicone microspheres is complex, and the encapsulation effect on glycerol is not very ideal. This preparation method still uses traditional glycerol as a plasticizer, resulting in insufficient aging resistance during long-term use of the material. If the product contacts a liquid, it is easy to cause the migration and precipitation of small molecule plasticizers.

[0005] Patent CN105623214A discloses a plasticized biodegradable polyester film and a preparation method thereof, which improve the resistance to precipitation and migration and the mechanical properties of the modified polyester material by adding diacetyl epoxy vegetable oil acid glycerol ester as a plasticizer. The epoxy bond in the molecular structure of diacetyl epoxy vegetable oil acid glycerol ester can react with the terminal hydroxyl groups and terminal carboxyl groups of PLA and PBAT to improve their compatibility. Diacetyl epoxy vegetable oil acid glycerol ester has a relatively weak plasticizing effect on starch with a polyhydroxy structure and is difficult to be applied to degradable materials in the starch system.

[0006] Therefore, it is very necessary to develop a modified PBAT material with resistance to migration and low precipitation and a preparation method thereof. Summary of the Invention

[0007] The object of the present invention is to provide a modified PBAT material with resistance to migration and exudation and a preparation method thereof. By introducing a self-made macromolecular polyester plasticizer, the problems of difficult feeding such as caking and bridging that occur after the starch contacts with small-molecule liquid plasticizers during the processing are effectively avoided; moreover, due to its large molecular weight and cage-like structure, it is quite resistant to volatilization during the material processing and final use, and both the migration property and the leaching property are greatly improved; in addition, due to its large free volume, more space for free movement of molecular chains is provided, improving the tensile property of the material.

[0008] To achieve the above object of the invention, the following technical solutions are adopted by the present invention:

[0009] A modified PBAT material with resistance to migration and exudation, and the modified PBAT material comprises the following components in percentage by weight:

[0010] S1, PBAT resin, 30%-85%, preferably 50%-70%;

[0011] S2, PLA resin, 0%-25%, preferably 5%-20%;

[0012] S3, modified starch, 10%-50%, preferably 20%-35%;

[0013] S4, slip agent, 0.1%-0.5%, preferably 0.2%-0.4%.

[0014] The total mass of the above components is counted as 100%.

[0015] The melt index of the PBAT resin described in the present invention is 3-20 / 10 min (190 °C, 2.16 kg), and the molecular weight is 40000-100000 g / mol.

[0016] The melt index of the PLA resin described in the present invention is 3-25 g / 10 min (190 °C, 2.16 kg), and the molecular weight is 60000-150000 g / mol.

[0017] The slip agent described in the present invention is one or more of oleic acid amide, ethylene bisstearamide, zinc stearate, ethylene bisoleamide, behenic acid amide, preferably one or more of zinc stearate and oleic acid amide.

[0018] The modified starch described in the present invention is polyester plasticizer-modified starch, and comprises the following components in mass fraction:

[0019] S5, starch, 40%-95%, preferably 70%-90%;

[0020] S6, polyester plasticizer, 5%-60%, preferably 10%-30%.

[0021] Based on the total mass of the above components being 100%.

[0022] The starch in the present invention is one or more of corn starch, cassava starch, and potato starch, preferably corn starch.

[0023] The polyester plasticizer in the present invention is a polyester formed by the reaction of polycarboxyl polyhedral oligomeric silsesquioxane (abbreviated as polycarboxyl POSS) and diol under the action of a catalyst.

[0024] Preferably, the polycarboxyl polyhedral oligomeric silsesquioxane is preferably a 6-8 carboxyl polyhedral oligomeric silsesquioxane, more preferably octacarboxyl polyhedral oligomeric silsesquioxane, such as one or more of POSS-octacarboxyl, POSS-octamethanecarboxyl, POSS-octaethanecarboxyl, POSS-octapropanecarboxyl, preferably one or more of POSS-octacarboxyl and POSS-octamethanecarboxyl.

[0025] The structural formulas of POSS-octacarboxyl, POSS-octamethanecarboxyl, POSS-octaethanecarboxyl, and POSS-octapropanecarboxyl are as follows:

[0026]

[0027] POSS-octacarboxyl: The R group is -COOH

[0028] POSS-octamethanecarboxyl: The R group is -CH 2 COOH

[0029] POSS-octaethanecarboxyl: The R group is -CH 2 CH 2 COOH

[0030] POSS-octapropanecarboxyl: The R group is -CH 2 CH 2 CH 2 COOH

[0031] The diol is a C2-C12 diol, preferably one or more of ethylene glycol, butanediol, hexanediol, heptanediol, octanediol, and nonanediol, more preferably one or more of hexanediol and octanediol.

[0032] The catalyst is an acid catalyst, preferably one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and phosphorous acid, more preferably phosphorous acid. The molar ratio of the catalyst dosage to the diol is 1:20 - 1:100, preferably 1:30 - 1:60.

[0033] The molar ratio of the polycarboxyl POSS to the diol is 1:1 - 1:10, preferably 1:3 - 1:8.

[0034] The reaction temperature of the multi-carboxyl POSS and the diol is 80-200 °C.

[0035] In one embodiment, the method for preparing the polyester plasticizer includes the following steps: in the presence of a catalyst, the multi-carboxyl POSS and the diol are fully mixed, heated at 80-120 °C, and kept at a constant temperature for 1-5 h, preferably heated at 90-115 °C and kept at a constant temperature for 2-3 h; then gradually heated to 120-200 °C and kept at a constant temperature for reaction for 4-10 h, preferably heated to 150-180 °C and kept at a constant temperature for reaction for 6-8 h; then cooled to 60-80 °C for reaction to obtain the polyester.

[0036] The obtained polyester is washed, separated, and subjected to vacuum distillation, etc. to obtain the polyester plasticizer described in the present invention.

[0037] Preferably, it is washed by adding saturated brine.

[0038] The modified starch described in the present invention is prepared by the following method: after mixing starch and the polyester plasticizer, it is melt-extruded in an extruder, cooled, and dried to obtain the modified starch.

[0039] Preferably, the extruder is a twin-screw extruder.

[0040] In the method for preparing the modified starch described in the present invention, a high-speed mixer is used for mixing, with a rotation speed of 20-80 rpm, preferably 30-60 rpm; the temperature is 20-40 °C, preferably 25-35 °C; the mixing time is 5-10 min; the screw temperature of the twin-screw extruder is 120-170 °C, preferably 130-150 °C; the rotation speed is 50-600 rpm, preferably 200-400 rpm.

[0041] Another object of the present invention is to provide a method for preparing a modified PBAT material with resistance to migration and exudation.

[0042] A method for preparing a modified PBAT material with resistance to migration and exudation includes the following steps: after mixing PBAT, PLA, modified starch, and a slip agent, it is melt-extruded in an extruder, cooled, and dried to obtain the modified PBAT material.

[0043] Preferably, the extruder is a twin-screw extruder.

[0044] In the method for preparing the modified PBAT material described in the present invention, a high-speed mixer is used for mixing, with a rotation speed of 20-120 rpm, preferably 50-80 rpm; the temperature is 20-40 °C, preferably 25-35 °C; the mixing time is 5-15 min; the screw temperature of the twin-screw extruder is 130-160 °C, preferably 140-150 °C; the rotation speed is 100-800 rpm, preferably 300-400 rpm.

[0045] Compared with the prior art, the present invention has the following technical advantages:

[0046] 1) In the present application, a self-made macromolecular polyester plasticizer is introduced to modify starch. The multi-carboxyl structure of the adopted polyester plasticizer has excellent compatibility and plasticizing ability for starch. At the same time, it effectively avoids the feeding difficulties such as caking and bridging that occur after starch contacts with small-molecule liquid plasticizers in the traditional processing process, as well as the die exudation and extrusion fuming problems that occur during the processing process.

[0047] 2) Since the self-made macromolecular polyester plasticizer has a large molecular weight and its multi-carboxyl structure is well grafted in starch and PBAT resin, it plays an excellent plasticizing and compatibilizing role during the PBAT modification process, and the molecular chains have a high entanglement degree with the PBAT matrix. During the material processing process and the use process of the final product, compared with small-molecule alcohol and ester plasticizers, it is more difficult to degrade and exude, and the migration resistance and leaching resistance are greatly improved.

[0048] 3) The macromolecular polyester plasticizer of the present application also has a cage structure, which can well adsorb the residual small molecules in the PBAT, PLA matrix resins and starch raw materials, as well as the small molecules generated in the initial stage of material degradation, and synergistically improve the exudation and stickiness on the surface of the modified PBAT product.

[0049] 4) The molecular spatial structure of the macromolecular polyester plasticizer of the present application is complex. Compared with small-molecule alcohol and ester plasticizers, after plasticizing and compatibilizing with the matrix resin and starch, there is a larger free volume between molecules, providing more free movement space for the molecular chains. At the material level, the toughness is greatly enhanced and the elongation at break of the tensile test is significantly improved. Detailed implementation manners

[0050] The present invention will be further described below through specific embodiments. The embodiments described in the present invention are only for the purpose of explaining the present invention and do not limit the scope of the present invention.

[0051] In each of the examples and comparative examples, the sources of the main raw materials are as shown in Table 1 below:

[0052] Table 1 Raw materials and sources

[0053] raw materials factory PLA(LX575) Total Cobien Polylactic Acid Co., Ltd. PLA(LX175) Total Cobien Polylactic Acid Co., Ltd. PBAT(801T) Xinjiang Blue Mountain Tunhe Polyester Co., Ltd. PBAT(C1200) BASF (China) Co., Ltd. Corn starch Shandong Shouguang Juneng Golden Corn Development Co., Ltd. Potato starch Shandong Shouguang Juneng Golden Corn Development Co., Ltd. Zinc stearate Shandong Siyang Biotechnology Co., Ltd. POSS-Octacyl (CA0298) Xi'an Qiyue Biotechnology Co., Ltd. Hexanediol Shanghai Aladdin Biochemical Technology Co., Ltd. Caprylyl glycol Shanghai Aladdin Biochemical Technology Co., Ltd. Phosphorous acid Shanghai Aladdin Biochemical Technology Co., Ltd. Sodium chloride Shanghai Aladdin Biochemical Technology Co., Ltd. glycerin Kangdis Chemical Co., Ltd. Sorbitol Esters Kangdis Chemical Co., Ltd. Modified Starch Masterbatch Xinjiang Blue Mountain Tunhe Polyester Co., Ltd.

[0054] Unless otherwise specified, other raw materials and reagents are obtained through commercial channels on the market.

[0055] In each of the examples and comparative examples, the performance test parameters and test methods of the modified PBAT materials are as shown in Table 2 below:

[0056] Table 2 Performance test parameters and methods

[0057] Test Parameters unit Test Method Melt index g / 10min ISO 1133 Tensile Strength MPa ISO 527-3 Tensile modulus MPa ISO 527-3 Elongation at break ％ ISO 527-3 Total migration <![CDATA[mg / dm 3 > GB 31604.1 Appearance evaluation / Visual Resistance to wet and hot aging-total migration <![CDATA[mg / dm 3 > ISO12000、GB 31604.1 Resistance to moisture and heat aging-tensile strength MPa ISO12000、ISO 527-3 Resistance to moist heat aging-tensile modulus MPa ISO12000、ISO 527-3 Resistance to heat and humidity aging-elongation at break ％ ISO12000、ISO 527-3 Heat and humidity aging resistance-appearance evaluation / ISO12000, visual inspection

[0058] The processing equipment used is as follows: a twin-screw extruder, Coperion, model ZSK 26Mc 18, with a length-diameter ratio of 52 and a screw diameter of 26 cm; a blown film machine, Zhangjiagang Lianjiang Machinery Co., Ltd., model SCM 25, with a length-diameter ratio of 30 and a screw diameter of 25 cm.

[0059] The testing equipment used is as follows: a German Gottfert melt indexer, with melt index test conditions of 190 °C and 2.16 kg; a German ZWICK universal material testing machine, with tensile test conditions of 500 mm / min; a Guangzhou Xitang Technology ERT-121-B total migration and non-volatile matter constant weight instrument, with total migration test conditions of 50% ethanol, 70 °C, and 2 h; a Japanese ESPEC damp heat aging chamber, with damp heat aging test conditions of 85 °C, RH 85%, and 240 h.

[0060] Example 1

[0061] (1) Preparation of polyester plasticizer (Polyester plasticizer-A)

[0062] Weigh 180 g of POSS-octacarboxyl and 80 g of hexanediol (the molar ratio of POSS-octacarboxyl to hexanediol is 1:3), add them to a triangular flask, add 1.6 g of phosphorous acid powder (the molar ratio of phosphorous acid to hexanediol is 1:30), continuously stir, heat up to 90 °C, and keep warm for 3 h; then gradually heat up to 150 °C and keep warm for 8 h; then cool down to 60 °C. Transfer all the liquid in the reaction system to 300 mL of saturated sodium chloride solution, wash and separate the layers, and take the oily layer; then under vacuum, rotary evaporate the unreacted monomers and small molecule substances to obtain the purified polyester plasticizer.

[0063] (2) Preparation of modified starch (Starch-A)

[0064] Weigh 700 g of corn starch and 300 g of polyester plasticizer (Polyester plasticizer-A), place them in a high-speed mixer, set the rotation speed to 30 rpm and the temperature to 35 °C, and mix for 5 min. Put the sample into a twin-screw extruder for melt extrusion, and set the screw temperature from the feeding port to the die head to 100 °C, 130 °C, 130 °C, 130 °C, 130 °C, 130 °C, 130 °C, 130 °C, 120 °C in sections, and set the screw rotation speed to 400 rpm. Cool and pelletize the extruded material in the extruder water tank, and dry it in an oven at 80 °C for 4 h to obtain the modified starch.

[0065] (3) Using the modified starch of this embodiment, the PBAT alloy is prepared by the following method. The mass dosage of each component is shown in Table 3. First, the PBAT and PLA resins are dried in an oven at 90 °C for 4 h; then the modified starch, PBAT resin, PLA resin and slip agent are placed in a high-speed mixer, the rotation speed is set at 50 rpm, the temperature is set at 35 °C, and mixed for 5 min. The sample is put into a twin-screw extruder for melt extrusion. The screw temperature is set in sections from the feeding port to the head as 120 °C, 140 °C, 140 °C, 140 °C, 140 °C, 140 °C, 140 °C, 140 °C, 140 °C, and the screw rotation speed is set at 300 rpm. The extruded material is cooled and pelletized in the water tank of the extruder, and dried in an oven at 80 °C for 4 h to obtain the modified PBAT material. The modified PBAT material is added to a single-screw extruder for extrusion and blowing film. The blowing film temperature is set in sections from the feeding port to the die head as 160 °C, 165 °C, 165 °C, 165 °C, 160 °C.

[0066] Example 2

[0067] (1) Preparation of polyester plasticizer (Polyester plasticizer-B)

[0068] Weigh 180 g of POSS-octacarboxyl and 160 g of hexanediol (the molar ratio of POSS-octacarboxyl to hexanediol is 1:6), add them to a triangular flask, add 2.4 g of phosphoric acid powder (the molar ratio of phosphoric acid to hexanediol is 1:45), continuously stir, heat up to 105 °C, and keep warm for 2.5 h; then gradually heat up to 165 °C and keep warm for 7 h; then cool down to 70 °C. Transfer all the liquids in the reaction system to 300 mL of saturated sodium chloride solution, wash and layer, and take the oily layer; then under vacuum, rotary evaporate the unreacted monomers and small molecular substances to obtain the purified polyester plasticizer.

[0069] (2) Preparation of modified starch (Starch-B)

[0070] Weigh 800 g of corn starch and 200 g of polyester plasticizer (Polyester plasticizer-B), place them in a high-speed mixer, set the rotation speed at 45 rpm, set the temperature at 30 °C, and mix for 10 min. The sample is put into a twin-screw extruder for melt extrusion. The screw temperature is set in sections from the feeding port to the head as 110 °C, 140 °C, 140 °C, 140 °C, 140 °C, 140 °C, 140 °C, 140 °C, 130 °C, and the screw rotation speed is set at 300 rpm. The extruded material is cooled and pelletized in the water tank of the extruder, and dried in an oven at 80 °C for 4 h to obtain the modified starch.

[0071] (3) The modified starch of this embodiment is adopted to prepare the PBAT alloy according to the following method. The mass dosage of each component is shown in Table 3. First, dry the PBAT and PLA resins in an oven at 90 °C for 4 h; then place the modified starch, PBAT resin, PLA resin, and slip agent in a high-speed mixer, set the rotation speed to 65 rpm, the temperature to 30 °C, and mix for 10 min. Put the sample into a twin-screw extruder for melt extrusion. The screw temperature is set in sections from the feeding port to the head as 125 °C, 145 °C, 145 °C, 145 °C, 145 °C, 145 °C, 145 °C, 145 °C, 145 °C, and the screw rotation speed is set to 350 rpm. Cool and pelletize the extruded material in the water tank of the extruder, and dry it in an oven at 80 °C for 4 h to obtain the modified PBAT material. Add the modified PBAT material to a single-screw extruder for extrusion and blowing film. The blowing film temperature is set in sections from the feeding port to the die head as 160 °C, 165 °C, 165 °C, 165 °C, 160 °C.

[0072] Example 3

[0073] (1) Prepare polyester plasticizer (Polyester plasticizer-C)

[0074] Weigh 180 g of POSS-octacarboxyl and 230 g of hexanediol (the molar ratio of POSS-octacarboxyl to hexanediol is 1:8), add them to a triangular flask, add 2.6 g of sulfuric acid (the molar ratio of sulfuric acid to hexanediol is 1:60), continuously stir, heat up to 115 °C, and keep warm for 2 h; then gradually heat up to 180 °C and keep warm for 6 h; then cool down to 80 °C. Transfer all the liquids in the reaction system to 300 mL of saturated sodium chloride solution, wash and separate the layers, and take the oily layer; then under vacuum, rotary evaporate the unreacted monomers and small molecule substances to obtain the purified polyester plasticizer.

[0075] (2) Prepare modified starch (Starch-C)

[0076] Weigh 900 g of potato starch and 100 g of polyester plasticizer (Polyester plasticizer-C), place them in a high-speed mixer, set the rotation speed to 60 rpm, the temperature to 25 °C, and mix for 10 min. Put the sample into a twin-screw extruder for melt extrusion. The screw temperature is set in sections from the feeding port to the head as 120 °C, 150 °C, 150 °C, 150 °C, 150 °C, 150 °C, 150 °C, 150 °C, 140 °C, and the screw rotation speed is set to 200 rpm. Cool and pelletize the extruded material in the water tank of the extruder, and dry it in an oven at 80 °C for 4 h to obtain the modified starch.

[0077] (3) The modified starch of this embodiment is adopted to prepare the PBAT alloy according to the following method, and the mass dosage of each component is shown in Table 3. First, dry the PBAT and PLA resins in an oven at 90 °C for 4 h; then place the modified starch, PBAT resin, PLA resin and slip agent in a high-speed mixer, set the rotation speed to 80 rpm, set the temperature to 25 °C, and mix for 15 min. Put the sample into a twin-screw extruder for melt extrusion, and set the screw temperature in sections from the feeding port to the die head as 130 °C, 150 °C, 150 °C, 150 °C, 150 °C, 150 °C, 150 °C, 150 °C, 150 °C, and set the screw rotation speed to 300 rpm. Cool and pelletize the extruded material in the water tank of the extruder, and dry it in an oven at 80 °C for 4 h to obtain the modified PBAT material. Add the modified PBAT material into a single-screw extruder for extrusion and blowing film, and set the blowing film temperature in sections from the feeding port to the die head as 160 °C, 165 °C, 165 °C, 165 °C, 160 °C.

[0078] Example 4

[0079] The modified starch and the modified PBAT alloy material are prepared by the same method as in Example 1, except that the proportions of the components in the PBAT alloy are different.

[0080] Example 5

[0081] The modified PBAT material is prepared according to the method in Example 1, except that the formulation composition in Table 3 is different. The multi-carboxyl POSS used is POSS-octacarboxyl, the diol is octanediol, and the polyester plasticizer prepared is Polyesterplasticizer-D. The modified starch thus prepared is Starch-D.

[0082] Comparative Example 1

[0083] The modified PBAT material is prepared according to the method in Example 1, except that the formulation composition in Table 3 is different. Commercially available glycerol is used to replace the self-made polyester plasticizer. The modified starch thus prepared is Starch-E.

[0084] Comparative Example 2

[0085] The modified PBAT material is prepared according to the method in Example 1, except that the formulation composition in Table 3 is different. Commercially available sorbitan ester is used to replace the self-made polyester plasticizer, and the modified starch thus prepared is Starch-F.

[0086] Comparative Example 3

[0087] The modified PBAT material is prepared according to the method in Example 1, except that the formulation composition in Table 3 is different. Commercially available modified starch masterbatch is used to replace the self-made modified starch.

[0088] For Examples 1-5 and Comparative Examples 1-3, the blown films of the modified PBAT materials were controlled to have a thickness of 25 microns for all films, and the performance test results are shown in Table 4.

[0089] Table 3 Raw materials and dosages (mass fraction) in Examples 1-5 (A1-A5) and Comparative Examples 1-3 (B1-B3)

[0090]

[0091]

[0092] Table 4 Performance test results of the samples in Examples 1-5 (A1-A5) and Comparative Examples 1-4 (B1-B4)

[0093]

[0094] It can be seen from Comparative Examples 1-3 and Example 1 that in the modification process of PBAT, compared with the traditional direct addition of small molecule plasticizers such as glycerol and sorbitan esters, the present invention effectively avoids the feeding difficulties such as caking and bridging that occur after the starch contacts with the small molecule liquid plasticizer during the processing by introducing a self-made macromolecular polyester plasticizer; and due to its large molecular weight and cage-like structure, it is quite resistant to volatilization during the material processing and final use, and both the migration and leaching properties are greatly improved; in addition, due to its large free volume, it provides more space for the molecular chains to move freely, improving the tensile properties of the material.

[0095] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the method of the present invention, several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A modified PBAT material with resistance to migration and precipitation, characterized in that, the modified PBAT material comprises the following components in weight percentages: S1, PBAT resin, 30%-85%, preferably 50%-70%; S2, PLA resin, 0%-25%, preferably 5%-20%; S3, modified starch, 10%-50%, preferably 20%-35%; S4, slip agent, 0.1%-0.5%, preferably 0.2%-0.4%; calculated based on the total mass of the above components being 100%.

2. The modified PBAT material according to claim 1, characterized in that, the PBAT resin has a melt index of 3-20 / 10 min and a molecular weight of 40,000-100,000 g / mol at 190 °C and 2.16 kg; preferably, the PLA resin has a melt index of 3-25 g / 10 min and a molecular weight of 60,000-150,000 g / mol at 190 °C and 2.16 kg; preferably, the slip agent is one or more of oleic acid amide, ethylene bisstearamide, zinc stearate, ethylene bisoleamide, behenic acid amide, preferably one or more of zinc stearate and oleic acid amide.

3. The modified PBAT material according to claim 1 or 2, characterized in that, the modified starch is polyester plasticizer modified starch, comprising the following components in mass fractions: S5, starch, 40%-95%, preferably 70%-90%; S6, polyester plasticizer, 5%-60%, preferably 10%-30%; calculated based on the total mass of the above components being 100%; preferably, the starch is one or more of corn starch, tapioca starch, potato starch, preferably corn starch.

4. The modified PBAT material according to any one of claims 1-3, characterized in that, the polyester plasticizer is a polyester formed by the reaction of polycarboxyl polyhedral oligomeric silsesquioxane, abbreviated as polycarboxyl POSS, with a diol under the action of a catalyst; preferably, the polycarboxyl polyhedral oligomeric silsesquioxane is preferably 6-8 carboxyl polyhedral oligomeric silsesquioxane, more preferably octacarboxyl polyhedral oligomeric silsesquioxane, further preferably one or more of POSS-octacarboxyl, POSS-octamethylcarboxyl, POSS-octaethylcarboxyl, POSS-octapropylcarboxyl, preferably one or more of POSS-octacarboxyl and POSS-octamethylcarboxyl; preferably, the diol is a C2-C12 diol, preferably one or more of ethylene glycol, butanediol, hexanediol, heptanediol, octanediol, nonanediol, more preferably one or more of hexanediol and octanediol; preferably, the catalyst is an acid catalyst, preferably one or more of hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, more preferably phosphorous acid.

5. The modified PBAT material according to claim 4, characterized in that, the molar ratio of the catalyst dosage to the diol is 1:20-1:100, preferably 1:30-1:60; preferably, the molar ratio of the polycarboxyl POSS to the diol is 1:1-1:10, preferably 1:3-1:8; Preferably, the reaction temperature of the multi-carboxyl POSS and the diol is 80 - 200 °C.

6. The modified PBAT material according to claim 4 or 5, wherein, the preparation method of the polyester plasticizer includes the following steps: in the presence of a catalyst, the multi-carboxyl POSS and the diol are fully mixed, heated at 80 - 120 °C, and kept at a constant temperature for 1 - 5 h, preferably heated at 90 - 115 °C and kept at a constant temperature for 2 - 3 h; then gradually heated to 120 - 200 °C and kept at a constant temperature for reaction for 4 - 10 h, preferably heated to 150 - 180 °C and kept at a constant temperature for reaction for 6 - 8 h; then cooled to 60 - 80 °C for reaction to prepare the polyester.

7. The modified PBAT material according to any one of claims 3 - 6, wherein, the modified starch is prepared by the following method: after mixing starch and the polyester plasticizer, it is added to an extruder for melt extrusion, cooled and dried to obtain the modified starch; Preferably, the extruder is a twin-screw extruder; Preferably, in the preparation method of the modified starch, high-speed mixing is used, the rotation speed is 20 - 80 rpm, preferably 30 - 60 rpm; the temperature is 20 - 40 °C, preferably 25 - 35 °C; the mixing time is 5 - 10 min; the screw temperature of the twin-screw extruder is 120 - 170 °C, preferably 130 - 150 °C; the rotation speed is 50 - 600 rpm, preferably 200 - 400 rpm.

8. A preparation method of the modified PBAT material according to any one of claims 1 - 7, wherein, it includes the following steps: after mixing PBAT, PLA, the modified starch, and the slip agent, it is added to an extruder for melt extrusion, cooled and dried to obtain the modified PBAT material Preferably, the extruder is a twin-screw extruder.

9. According to the preparation method of claim 8, wherein, high-speed mixing is used for mixing, the rotation speed is 20 - 120 rpm, preferably 50 - 80 rpm; the temperature is 20 - 40 °C, preferably 25 - 35 °C; the mixing time is 5 - 15 min; the screw temperature of the twin-screw extruder is 130 - 160 °C, preferably 140 - 150 °C; the rotation speed is 100 - 800 rpm, preferably 300 - 400 rpm.

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