Preparation method of PBAT-PLA resin film

Abstract

The invention discloses a PBAT-PLA resin film preparation method, which comprises: weighing 5-95% by mass of poly (butylene adipate-co-terephthalate), 5-95% by mass of polylactic acid, 0.3-1.5% by mass of a compatibilizer, 0.2-0.5% by mass of an antioxidant, and 0.2-0.5% by mass of a slipping agent, feeding into a high-speed mixer, and mixing to obtain a mixed material; adding the mixed material into a double-screw extruder, and carrying out melt blending extrusion to obtain resin granules; adding the resin granules into a casting machine, and extruding to form a casting piece; and carrying out synchronous two-way stretching and heat setting on the cast sheet, and rolling to obtain the PBAT-PLA resin film. The PBAT-PLA resin film disclosed by the invention has good degradability, high flatness, high transparency and good barrier property.

Description

Technical Field

[0001] The present invention relates to the technical field of resin films, and in particular to a method for preparing a PBAT-PLA resin film. Background Art

[0002] Compared with traditional cast film and blown film, biaxially oriented film has better mechanical properties, optical properties, barrier properties and good processability at a smaller film thickness, and is widely used in the fields of pharmaceutical packaging, food packaging, daily necessities packaging and printed surface decoration. At present, biaxially oriented polypropylene film (BOPP), biaxially oriented polyester film (BOPET) and biaxially oriented nylon film (BOPA) are the most widely used biaxially oriented flexible packaging materials. However, traditional films such as BOPP, BOPET and BOPA are polymer materials that are difficult to degrade and cause great pollution to the environment. Therefore, how to use degradable materials to replace traditional polymer materials is an important exploration direction.

[0003] In recent years, in addition to common natural biodegradable polymer materials such as starch, lignin, cellulose, etc., a large number of polymer-based biodegradable polymer materials have emerged, such as polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), polycaprolactone (PCL) and polybutylene succinate (PBS). Among them, PBAT has great elongation at break and soft properties, while PLA has high modulus and low toughness. The advantages and disadvantages of the two can complement each other well, but PBAT and PLA are thermodynamically incompatible systems. How to prepare PBAT-PLA composite materials that can be widely used in the packaging field has become a hot research issue.

[0004] On this basis, how to combine the biaxial stretching process with the PBAT-PLA material to improve the comprehensive performance of the film and achieve the purpose of expanding the application scope of the PBAT-PLA material is a technical problem that urgently needs to be solved. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for preparing a PBAT-PLA resin film, aiming to solve the above-mentioned technical problems in the background technology.

[0006] To achieve the above object, the present invention provides a method for preparing a PBAT-PLA resin film, comprising: weighing 5-95% of polybutylene adipate-terephthalate, 5-95% of polylactic acid, 0.3-1.5% of a compatibilizer, 0.2-0.5% of an antioxidant and 0.2-0.5% of a lubricant according to mass percentage;

[0007] The polybutylene adipate-terephthalate, the polylactic acid, the compatibilizer, the antioxidant and the lubricant are fed into a high-speed mixer and mixed to obtain a mixed material;

[0008] The mixed material is added into a twin-screw extruder, and melt-blended and extruded to obtain PBAT-PLA resin pellets;

[0009] Adding the PBAT-PLA resin pellets into a tape casting machine to form a tape casting sheet through extrusion;

[0010] The cast sheet is subjected to synchronous biaxial stretching and heat setting, and then rolled up to obtain a PBAT-PLA resin film.

[0011] Preferably, the compatibilizer is lanthanum acetylacetonate.

[0012] Preferably, the antioxidant is a compound of a phosphite antioxidant and a polyhydric hindered phenol antioxidant.

[0013] Preferably, the lubricant is at least one of ethylene bisstearamide, erucamide, oleamide and zinc stearate.

[0014] Preferably, the polybutylene adipate-terephthalate, the polylactic acid, the compatibilizer, the antioxidant and the lubricant are fed into a high-speed mixer and mixed to obtain a mixed material, comprising:

[0015] The polybutylene adipate-terephthalate and the polylactic acid are added into a high-speed mixer, stirred and mixed at a preset first stirring speed, and then the compatibilizer, the antioxidant and the lubricant are added, stirred and mixed at a preset second stirring speed to obtain a mixed material.

[0016] Preferably, the mixed material is added into a twin-screw extruder, and melt-blended and extruded to obtain PBAT-PLA resin pellets, comprising:

[0017] The mixed material is added into a twin-screw extruder, melt-blended and extruded at a preset melt co-extrusion temperature, and then water-cooled, air-dried, pelletized and dried to obtain PBAT-PLA resin pellets; wherein the preset melt co-extrusion temperature is 165-200°C.

[0018] Preferably, the PBAT-PLA resin pellets are added into a tape casting machine to form a tape casting sheet by extrusion, comprising:

[0019] The PBAT-PLA resin pellets are added to a tape casting machine and extruded through a single-layer extrusion die head at a preset extrusion temperature to form a tape casting sheet of a preset thickness; wherein the preset extrusion temperature is 185-200° C., and the preset thickness is 300-500 μm.

[0020] Preferably, the cast sheet is subjected to synchronous biaxial stretching and heat setting, and then rolled up to obtain a PBAT-PLA resin film, comprising:

[0021] The cast sheet is preheated to be synchronously biaxially stretched at a preset stretching ratio, a preset stretching rate and a preset stretching temperature, then heat-set at a preset heat setting temperature, and then wound at a preset winding speed to obtain a PBAT-PLA resin film; wherein the preset stretching ratio is λ×λ, the value range of λ is [2,5], the preset stretching rate is 100-500 mm / sec, the preset stretching temperature is 110-120°C, the preset heat setting temperature is 70°C, and the preset winding speed is 100-300 mm / sec.

[0022] The above-mentioned method for preparing the PBAT-PLA resin film has the following beneficial effects:

[0023] 1) The present invention adopts a synchronous biaxial stretching process to prepare a PBAT-PLA resin film. Compared with the blown film process, at the same film thickness, the film has better mechanical properties, flatness, transparency and barrier properties. At the same time, the present invention uses polybutylene adipate-terephthalate and polylactic acid as base materials to prepare a PBAT-PLA resin film. The film has good degradability and can meet the use requirements of degradable packaging films;

[0024] 2) The present invention improves the compatibility of polybutylene adipate-terephthalate and polylactic acid by adding a compatibilizer, thereby improving the tensile strength of the film, adding a lubricant to improve the processing fluidity of the film, and adding an antioxidant to reduce the degradation phenomenon during the simultaneous biaxial stretching process to avoid film breakage or obvious strength loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the process of preparing a PBAT-PLA resin film in one embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation methods. It should be understood that the specific implementation methods described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Reference Figure 1 In one embodiment, the present invention provides a method for preparing a PBAT-PLA resin film, which specifically comprises the following steps:

[0028] Step S10, weighing 5-95% of polybutylene adipate-terephthalate, 5-95% of polylactic acid, 0.3-1.5% of a compatibilizer, 0.2-0.5% of an antioxidant and 0.2-0.5% of a lubricant according to their mass percentages.

[0029] In this embodiment, the compatibilizer is lanthanum acetylacetonate (La(acac)3), and the purity of lanthanum acetylacetonate is ≥98%. The antioxidant is a compound of a phosphite antioxidant and a polyhydric hindered phenol antioxidant, and the weight ratio of the phosphite antioxidant to the polyhydric hindered phenol antioxidant is 1:1. The lubricant is at least one of ethylene bis stearamide (EBS), erucamide, oleamide and zinc stearate.

[0030] Polybutylene adipate-terephthalate (PBAT) can be selected from commercially available PBAT, for example, PBAT with the brand name Ecoflex produced by BASF of Germany, PBAT with the brand names FLEX-262 and EBAG-262 produced by Guangdong Kingfa Science & Technology, and PBAT with the brand name Ecoworld produced by Shanxi Jinhui Zhaolong.

[0031] Polylactic acid (PLA) can be selected from commercially available polylactic acid, for example, polylactic acid with grades LX175, LX130, and LX530 produced by Total Corbivir, polylactic acid with grades 4032D and 3001D produced by NatureWorks of the United States, polylactic acid with grades FY801, FY802, and FY601 produced by Anhui Fengyuan, and polylactic acid with grade REVODE110 produced by Zhejiang Hisun.

[0032] The compatibilizer can be selected from commercially available lanthanum acetylacetonate, for example, lanthanum acetylacetonate with the product name of Indonesia EBS and model number of P-130. Lanthanum acetylacetonate mainly plays a role in improving the compatibility of PBAT and polylactic acid. Lanthanum acetylacetonate has a certain catalytic activity, which can promote the chemical reaction between the active groups on the molecular chains of PBAT and PLA to form chemical bonds or cross-linked structures, thereby enhancing the binding force between the two and improving compatibility.

[0033] Erucic acid amide can be selected from erucic acid amide with a CAS number of 112-84-5 produced by Nantong Runfeng Petrochemical Co., Ltd. Oleic acid amide can be selected from oleic acid amide with a brand name of Paiswell produced by Shanghai Lawen New Materials Technology Co., Ltd. Zinc stearate can be selected from zinc stearate with a brand name of ZnST-75GE produced by Ningbo Aikemu New Materials Co., Ltd.

[0034] The phosphite antioxidant can be Antioxidant 168 produced by Nanjing Hualiming; the polyhedral hindered phenol antioxidant can be Antioxidant 1010 produced by Shanghai Pet Chemical.

[0035] Step S20, feeding the polybutylene adipate-terephthalate, the polylactic acid, the compatibilizer, the antioxidant and the lubricant into a high-speed mixer, and mixing them to obtain a mixed material.

[0036] More specifically, the polybutylene adipate-terephthalate and the polylactic acid are added to a high-speed mixer, stirred and mixed at a preset first stirring speed, and then the compatibilizer, the antioxidant and the lubricant are added, and stirred and mixed at a preset second stirring speed to obtain a mixed material. The preset first stirring speed is 300-350 r / min, and the preset second stirring speed is 450-500 r / min.

[0037] It can be understood that in this embodiment, PBAT and PLA are first mixed at a moderate stirring speed to ensure that the two base materials are fully contacted and evenly dispersed in the initial mixing stage, and then the compatibilizer, antioxidant and lubricant are added and stirred at a high speed to quickly disperse and integrate the newly added additives.

[0038] Step S30, adding the mixed material into a twin-screw extruder, and melt-blending and extruding to obtain PBAT-PLA resin pellets.

[0039] More specifically, the mixed material is added to a twin-screw extruder, melt-blended and extruded at a preset melt co-extrusion temperature, and then water-cooled, air-dried, pelletized and dried to obtain PBAT-PLA resin pellets; wherein the preset melt co-extrusion temperature is 165 to 200° C. Preferably, the twin-screw extruder can be a parallel twin-screw extruder.

[0040] Step S40, adding the PBAT-PLA resin pellets into a tape casting machine, and forming a tape casting sheet by extrusion.

[0041] More specifically, the PBAT-PLA resin pellets are added to a tape casting machine and extruded through a single-layer extrusion die at a preset extrusion temperature to form a tape casting sheet of a preset thickness; wherein the preset extrusion temperature is 185-200° C., and the preset thickness is 300-500 μm.

[0042] It is understandable that the casting machine in step S40 can be a twin-screw casting machine.

[0043] Step S50, after the cast sheet is subjected to synchronous biaxial stretching and heat setting, it is rolled up to obtain a PBAT-PLA resin film.

[0044] More specifically, the cast sheet is preheated to first perform synchronous biaxial stretching at a preset stretching ratio, a preset stretching rate and a preset stretching temperature, then perform heat setting at a preset heat setting temperature, and then wind up at a preset winding speed to obtain a PBAT-PLA resin film; wherein the preset stretching ratio is λ×λ, the value range of λ is [2,5], the preset stretching rate is 100-500 mm / sec, the preset stretching temperature is 110-120°C, the preset heat setting temperature is 70°C, and the preset winding speed is 100-300 mm / sec.

[0045] It is understandable that the synchronous biaxial stretching in step S50 refers to simultaneous stretching in equal proportions in the machine direction (abbreviated as “MD”) and the transverse direction (abbreviated as “TD”).

[0046] In summary, the method for preparing the PBAT-PLA resin film of this embodiment has the following beneficial effects:

[0047] 1) This embodiment adopts a synchronous biaxial stretching process to prepare a PBAT-PLA resin film. Compared with the blown film process, at the same film thickness, the film has better mechanical properties, flatness, transparency and barrier properties. At the same time, the present invention uses polybutylene adipate-terephthalate and polylactic acid as base materials to prepare a PBAT-PLA resin film. The film has good degradability and can meet the use requirements of degradable packaging films;

[0048] 2) In this embodiment, a compatibilizer is added to improve the compatibility of polybutylene adipate-terephthalate and polylactic acid, thereby improving the tensile strength of the film, a lubricant is added to improve the processing fluidity of the film, and an antioxidant is added to reduce the degradation phenomenon during the simultaneous biaxial stretching process to avoid film breakage or obvious strength loss.

[0049] The present invention will now be described by way of the following examples, which are not intended to limit the purpose of the present invention and / or the scope of the above embodiments.

[0050] Embodiment 1:

[0051] A method for preparing a PBAT-PLA resin film comprises the following steps:

[0052] Step a, weighing 95wt% of polybutylene adipate-terephthalate, 5wt% of polylactic acid, 0.5wt% of compatibilizer, 0.2wt% of antioxidant and 0.2wt% of lubricant by weight percentage for standby use; wherein, polybutylene adipate-terephthalate is polybutylene adipate-terephthalate with a brand name of Ecoworld produced by Shanxi Jinhui Zhaolong, polylactic acid is polylactic acid with a brand name of 4032D produced by NatureWorks, USA, the compatibilizer is lanthanum acetylacetonate, the antioxidant is a compound composed of antioxidant 168 and antioxidant 1010 in a weight ratio of 1:1, and the lubricant is a compound composed of ethylene bisstearamide, erucamide, oleamide and zinc stearate in a weight ratio of 1:1:1:1;

[0053] Step b, feeding the prepared polybutylene adipate-terephthalate and polylactic acid into a high-speed mixer, stirring at a speed of 350 r / min for 5 min, adding a compatibilizer, an antioxidant and a lubricant, and continuing to stir at a speed of 480 r / min for 10 min to obtain a mixed material;

[0054] Step c, adding the mixture into a twin-screw extruder, performing melt blending and extrusion at a temperature of 180° C., and then water cooling, air drying, pelletizing and drying to obtain PBAT-PLA resin pellets;

[0055] Step d, adding PBAT-PLA resin pellets into a tape casting machine, and extruding through a single-layer extrusion die head at a temperature of 200° C. to form a tape casting sheet;

[0056] Step e, the cast sheet is first subjected to synchronous biaxial stretching at a stretching temperature of 120° C., a stretching ratio of 2×2, and a stretching rate of 100 mm / sec, then heat-set at a temperature of 70° C., and finally rolled up at a winding rate of 100 mm / sec to obtain a PBAT-PLA resin film.

[0057] Embodiment 2:

[0058] A method for preparing a PBAT-PLA resin film, which differs from Example 1 only in that the following components are weighed in percentage by weight: 75 wt% of butylene adipate terephthalate, 25 wt% of polylactic acid, 0.5 wt% of a compatibilizer, 0.2 wt% of an antioxidant, and 0.2 wt% of a lubricant.

[0059] Embodiment 3:

[0060] A method for preparing a PBAT-PLA resin film, compared with Example 1, has the following differences: weighing the following components in weight percentage: 25wt% of polybutylene adipate-terephthalate, 75wt% of polylactic acid, 0.5wt% of a compatibilizer, 0.2wt% of an antioxidant, and 0.2wt% of a lubricant; and synchronously biaxially stretching the cast sheet at stretching ratios of 2×2, 3×3, 4×5, and 5×5, respectively.

[0061] Embodiment 4:

[0062] A method for preparing a PBAT-PLA resin film, which differs from Example 1 only in that the following components are weighed in percentage by weight: 5 wt% of polybutylene adipate-terephthalate, 95 wt% of polylactic acid, 0.5 wt% of a compatibilizer, 0.2 wt% of an antioxidant, and 0.2 wt% of a lubricant.

[0063] Embodiment 5:

[0064] A method for preparing a PBAT-PLA resin film, which differs from Example 1 only in that the following components are weighed in percentage by weight: 25 wt% of polybutylene adipate-terephthalate, 75 wt% of polylactic acid, 0.3 wt% of a compatibilizer, 0.2 wt% of an antioxidant, and 0.2 wt% of a lubricant.

[0065] Embodiment 6:

[0066] A method for preparing a PBAT-PLA resin film, which differs from Example 1 only in that the following components are weighed in percentage by weight: 25 wt% of polybutylene adipate-terephthalate, 75 wt% of polylactic acid, 1.5 wt% of a compatibilizer, 0.2 wt% of an antioxidant, and 0.2 wt% of a lubricant.

[0067] Embodiment 7:

[0068] A method for preparing a PBAT-PLA resin film, which differs from Example 1 only in that the following components are weighed in percentage by weight: 75 wt% of polybutylene adipate-terephthalate, 25 wt% of polylactic acid, 0.5 wt% of a compatibilizer, 0.3 wt% of an antioxidant, and 0.3 wt% of a lubricant.

[0069] Embodiment 8:

[0070] A method for preparing a PBAT-PLA resin film, which differs from Example 1 only in that the following components are weighed in percentage by weight: 75 wt% of polybutylene adipate-terephthalate, 25 wt% of polylactic acid, 0.5 wt% of a compatibilizer, 0.5 wt% of an antioxidant, and 0.5 wt% of a lubricant.

[0071] The performance test of the PBAT-PLA resin film in the above-mentioned embodiments 1 to 8 is carried out, and the test method is as follows: before preparing the test, the film sample is placed at 23°C and 50% RH for constant temperature and humidity treatment for 48 hours, and the treated film sample is tested at a tensile speed of 50mm / min, and five sample data are measured in each group, and the average value is taken; the absorbance is measured by ultraviolet spectrophotometer, and the PBAT-PLA resin film is cut into 4 cm × 1 cm rectangular splines, close to the inner surface of one side of the colorimetric cup of the spectrophotometer, and the absorbance at a wavelength of 660nm is measured, and repeated three times to reflect the opacity of the film; the oxygen permeability coefficient is tested according to the national standard GB1038-2000; the surface roughness of the film is measured by atomic force microscopy (AFM), and the surface morphology of the film is observed in the tapping mode. The force constant of the probe is 48N / m, the vibration frequency is 330kHz, and the scanning speed range is 0.5-2.0Hz. After the above tests, the test results of embodiments 1 to 8 are shown in Table 1.

[0072] Table 1

[0073]

[0074] According to Examples 1 to 8 in Table 1, it can be seen that with the increase of PLA content, the comprehensive performance of PBAT-PLA resin film is more excellent, which is specifically manifested in the significant improvement of tensile strength, flatness, transparency and oxygen barrier properties of the film; it can be seen from Example 3 that under the same component ratio, the stretch ratio increases, and the surface performance of the film is improved, which is specifically manifested in that the surface of the film is smoother and the transparency is better; it can be seen from Examples 3, 5 and 6 that with the increase of compatibilizer content, the tensile strength and oxygen barrier properties of the film are gradually enhanced; it can be seen from Examples 2, 7 and 8 that when the content of antioxidant and lubricant is gradually reduced, the transparency and oxygen barrier properties of the film are better. Therefore, PLA has a greater influence on the comprehensive properties of the film, the stretch ratio has a greater influence on the surface properties of the film, and the compatibilizer has a greater influence on the mechanical properties of the film.

[0075] Comparative Example 1:

[0076] A method for preparing a PBAT-PLA resin film, which differs from Example 1 only in that the following components are weighed in weight percentage: 0 wt% of polybutylene adipate-terephthalate, 100 wt% of polylactic acid, 0.5 wt% of a compatibilizer, 0.2 wt% of an antioxidant, and 0.2 wt% of a lubricant.

[0077] Comparative Example 2:

[0078] A method for preparing a PBAT-PLA resin film, which differs from Example 1 only in that the following components are weighed in percentage by weight: 95 wt% of polybutylene adipate-terephthalate, 5 wt% of polylactic acid, 0.2 wt% of a compatibilizer, 0.2 wt% of an antioxidant, and 0.2 wt% of a lubricant.

[0079] Comparative Example 3:

[0080] A PBAT-PLA resin film, which is different from Example 3 only in that the stretching ratio is replaced from 5×5 to 5×1.

[0081] The performance tests were performed on the PBAT-PLA resin films in Comparative Examples 1 to 3. The test results are shown in Table 2.

[0082] Table 2

[0083]

[0084] It can be seen from Example 4 in Table 1 and Comparative Example 1 in Table 2 that when the pure PLA cast sheet material is stretched under this process, film breakage will occur.

[0085] It can be seen from Example 1 in Table 1 and Comparative Example 2 in Table 2 that a decrease in the amount of compatibilizer added will result in a decrease in the mechanical properties of the film. Therefore, when the content of the compatibilizer is 0.5 wt%, the film has more outstanding mechanical properties.

[0086] According to Example 3 in Table 1 and Comparative Example 3 in Table 2, it can be seen that the film surface is smoother and has better transparency when the biaxial stretching is performed in equal ratios than when the uniaxial stretching is performed. Therefore, when the biaxial stretching is performed in equal ratios, the PBAT-PLA resin material film has more outstanding surface properties.

[0087] It should be noted that, in this article, the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a product or method including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such product or method. In the absence of more restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the product or method including the element.

[0088] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a PBAT-PLA resin film, characterized in that: include: Weigh 5-95% of polybutylene adipate-terephthalate, 5-95% of polylactic acid, 0.3-1.5% of compatibilizer, 0.2-0.5% of antioxidant and 0.2-0.5% of lubricant according to mass percentage; The polybutylene adipate-terephthalate, the polylactic acid, the compatibilizer, the antioxidant and the lubricant are fed into a high-speed mixer and mixed to obtain a mixed material; The mixed material is added into a twin-screw extruder, and melt-blended and extruded to obtain PBAT-PLA resin pellets; Adding the PBAT-PLA resin pellets into a tape casting machine to form a tape casting sheet through extrusion; The cast sheet is subjected to synchronous biaxial stretching and heat setting, and then rolled up to obtain a PBAT-PLA resin film.

2. The method for preparing the PBAT-PLA resin film according to claim 1, characterized in that: The compatibilizer is lanthanum acetylacetonate.

3. The method for preparing the PBAT-PLA resin film according to claim 1, characterized in that: The antioxidant is a compound of a phosphite antioxidant and a polyhydric hindered phenol antioxidant.

4. The method for preparing the PBAT-PLA resin film according to claim 1, characterized in that: The lubricant is at least one of ethylene bisstearamide, erucamide, oleamide and zinc stearate.

5. The method for preparing the PBAT-PLA resin film according to claim 1, characterized in that: The polybutylene adipate-terephthalate, the polylactic acid, the compatibilizer, the antioxidant and the lubricant are fed into a high-speed mixer and mixed to obtain a mixed material, comprising: The polybutylene adipate-terephthalate and the polylactic acid are added into a high-speed mixer, stirred and mixed at a preset first stirring speed, and then the compatibilizer, the antioxidant and the lubricant are added, stirred and mixed at a preset second stirring speed to obtain a mixed material.

6. The method for preparing the PBAT-PLA resin film according to claim 1, characterized in that: The mixed material is added into a twin-screw extruder, and melt-blended and extruded to obtain PBAT-PLA resin pellets, comprising: The mixed material is added into a twin-screw extruder, melt-blended and extruded at a preset melt co-extrusion temperature, and then water-cooled, air-dried, pelletized and dried to obtain PBAT-PLA resin pellets; wherein the preset melt co-extrusion temperature is 165-200°C.

7. The method for preparing the PBAT-PLA resin film according to claim 1, characterized in that: The PBAT-PLA resin pellets are added into a tape casting machine to form a tape casting sheet through extrusion, comprising: The PBAT-PLA resin pellets are added to a tape casting machine and extruded through a single-layer extrusion die head at a preset extrusion temperature to form a tape casting sheet of a preset thickness; wherein the preset extrusion temperature is 185-200° C., and the preset thickness is 300-500 μm.

8. The method for preparing the PBAT-PLA resin film according to claim 1, characterized in that: The method comprises: subjecting the cast sheet to synchronous biaxial stretching and heat setting, and then rolling up to obtain a PBAT-PLA resin film. The cast sheet is preheated to be firstly subjected to synchronous biaxial stretching at a preset stretching ratio, a preset stretching rate and a preset stretching temperature, then heat-set at a preset heat setting temperature, and then wound at a preset winding speed to obtain a PBAT-PLA resin film; wherein the preset stretching ratio is λ×λ, the value range of λ is [2,5], the preset stretching rate is 100-500 mm / sec, the preset stretching temperature is 110-120°C, the preset heat setting temperature is 70°C, and the preset winding speed is 100-300 mm / sec.

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