Biodegradable composition as well as preparation method and application thereof

Abstract

The invention provides a biodegradable composition as well as a preparation method and application thereof. The biodegradable composition comprises the following components in parts by weight: 45-70 parts of polylactic acid; 5 to 25 parts of poly (butylene succinate-adipate); 15-35 parts of an inorganic filler; 0-3 parts of a processing aid; the molecular structure of the polylactic acid comprises an L-lactic acid structural unit and a D-lactic acid structural unit, and the content of the D-lactic acid structural unit relative to the polylactic acid is 0.1-2 mol%; the acid value of the poly (butylene succinate / adipate) is less than or equal to 1.2 mgKOH / g. The biodegradable composition provided by the invention has excellent mechanical properties, good rigidity, toughness, low-temperature toughness and heat resistance, and can still maintain good mechanical properties after thermal aging.

Description

Technical Field

[0001] The invention belongs to the technical field of degradable plastics and relates to a biodegradable composition and a preparation method and application thereof. Background Art

[0002] The emergence of polymer plastics has brought convenience to production and life, but due to its difficulty in degradation and absorption by the natural environment, excessive accumulation has also caused serious environmental pollution. Therefore, replacing traditional plastics with biodegradable plastics has become a current research and development hotspot.

[0003] At present, the main raw materials used in major degradable plastics are polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), polypropylene carbonate (PPC) and polycaprolactone (PCL), among which PLA and PHA are completely renewable, completely free from dependence on petroleum resources, and alleviate the problem of shortage of petroleum resources. The main raw materials of PLA are plants such as corn, sucrose and cassava, which are beneficial to increase the added value of crops; one of the main raw materials of PPC is carbon dioxide, which is beneficial to alleviate or even solve the greenhouse effect. PBAT is a copolymer of butylene adipate and butylene terephthalate, and has the characteristics of PBA and PBT. PBAT contains flexible fatty chains and rigid aromatic chains, so it has high toughness and high temperature resistance. Due to the presence of ester bonds, it is also biodegradable. It is currently one of the most active biodegradable materials in the research of biodegradable plastics and the best market application.

[0004] CN114854079A discloses a biodegradable heat-resistant PLA blister tableware, wherein the raw materials of the PLA blister tableware include PLA, PBAT, filler and modifier. However, due to the defects of low strength and weak crystallization ability of PBAT raw materials, the mechanical properties of the PLA blister tableware are poor, and it is difficult to be comparable to products made of traditional plastics as raw materials. After a certain degree of thermal aging, the mechanical properties of the PLA blister tableware will further decrease, and the aging resistance is poor, so it cannot be applied in actual long-term use.

[0005] Therefore, it is desirable in the art to provide a biodegradable polymer composition having good mechanical properties and aging resistance. Summary of the invention

[0006] In view of the deficiencies of the prior art, the object of the present invention is to provide a biodegradable composition and a preparation method and application thereof. The biodegradable composition provided by the present invention has excellent mechanical properties, good rigidity, toughness, low-temperature toughness and heat resistance, and can still maintain good mechanical properties after thermal aging.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a biodegradable composition, the biodegradable composition comprising the following components in parts by weight:

[0009]

[0010] The molecular structure of the polylactic acid comprises a L-lactic acid structural unit (L-type) and a D-lactic acid structural unit (D-type); and the content of the D-lactic acid structural unit relative to the polylactic acid is 0.1 to 2 mol%, for example, it can be 0.1 mol%, 0.2 mol%, 0.3 mol%, 0.5 mol%, 0.8 mol%, 1 mol%, 1.2 mol%, 1.4 mol%, 1.5 mol%, 1.6 mol%, 1.8 mol%, 2 mol% or a range between any of the above values.

[0011] The acid value of the polybutylene succinate adipate is ≤1.2 mgKOH / g, for example, it may be 1.2 mgKOH / g, 1.1 mgKOH / g, 1.0 mgKOH / g, 0.9 mgKOH / g, 0.8 mgKOH / g, 0.7 mgKOH / g, 0.6 mgKOH / g, 0.5 mgKOH / g or a range between any of the above values.

[0012] In the present invention, in the biodegradable composition, the amount of polylactic acid (PLA) can be 45 parts, 46 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 70 parts or a range between any of the above values.

[0013] In the present invention, in the biodegradable composition, the amount of polybutylene succinate adipate (PBSA) can be 5 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 25 parts or a range between any of the above values.

[0014] In the present invention, in the biodegradable composition, the amount of the inorganic filler can be 15 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 35 parts or a range between any of the above values.

[0015] In the present invention, the amount of the processing aid in the biodegradable composition can be 0 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 parts, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts or ranges between any of the above values.

[0016] In the present invention, the content of polylactic acid in the biodegradable composition is not less than 50 wt %.

[0017] The invention compounded PLA and PBSA in specific weight proportions, with PLA as a continuous phase and PBSA as a dispersed phase, and under the synergistic effect of inorganic fillers, the molar content of the dextrorotatory lactic acid structural unit in PLA and the acid value of PBSA were controlled within specific ranges, so that the biodegradable composition had excellent mechanical properties, good rigidity, toughness, low-temperature toughness and heat resistance, and could still maintain good mechanical properties after thermal aging.

[0018] PLA is polymerized from lactic acid monomers. Lactic acid monomer molecules are chiral molecules and can be divided into L-type chiral structures and D-type chiral structures.

[0019] The content of the dextrorotatory lactic acid structural unit in polylactic acid relative to polylactic acid can be detected by the following method: using a catalyst to hydrolyze polylactic acid in methanol so that all lactic acid monomers in the molecule are converted into methyl lactate, and then analyzing by gas chromatography. The total peak area ratio of D-methyl lactate to D-methyl lactate and L-methyl lactate is the content of the dextrorotatory lactic acid structural unit in polylactic acid. The detection can be carried out according to the following steps: (1) weighing 100±10 mg of ground polylactic acid sample and placing it in a 25 mL pressurized container; (2) adding 10 mL of methanol and 1 drop of dilute sulfuric acid; (3) sealing the pressurized container and placing it in a thermostat at 150°C for 4 hours; (4) taking out the pressurized container and opening the lid after the container cools to room temperature; (5) filtering the obtained sample solution through a membrane filter (pore size 0.22 μm or 0.45 μm), transferring it to a special injection vial for gas chromatography, and using Agilent The test was performed using a 8860 gas chromatograph; (6) the content of the right-lactic acid structural unit in the polylactic acid was calculated based on the peak area ratio.

[0020] PLA with a content of 0.1-2 mol% of dextrorotatory lactic acid structural units is a semi-crystalline PLA with a high melting point. After crystallization, it has a high heat resistance temperature and can improve the rigidity and heat resistance temperature of the biodegradable composition. When the content of dextrorotatory lactic acid structural units exceeds this range, the melting point of PLA decreases and the crystallization effect becomes worse. When the content of dextrorotatory lactic acid structural units is higher than 12 mol%, the corresponding PLA becomes amorphous PLA with no heat resistance and serious performance degradation after aging.

[0021] The acid value of PBSA is tested according to DIN EN 12634-1998. The specific testing method is as follows: First, 6 g of sample is added to 150 mL of a solvent mixture formed by dimethyl sulfoxide, isopropanol and toluene (the volume ratio of dimethyl sulfoxide, isopropanol and toluene is 1:8:7), and heated to 70-85°C to dissolve all the sample into a clear solution. During the titration process, the solution temperature is maintained at 65-75°C to avoid sample precipitation. The titrant is a tetrabutylammonium hydroxide solution with a concentration of 0.1 mol / L, and the volume of the titrant is 2-3 mL. Avoid using highly toxic tetramethylammonium hydroxide. At the same time, to prevent the solvent mixture from absorbing CO in the air, 2 This will affect the volume of the blank solvent consumed by the titrant. When testing the volume of the blank solvent consumed by the titrant, the blank solvent should be pre-treated according to the same process as the sample test operation, such as heating the blank solvent for the same time and temperature, and then titrating the blank solvent.

[0022] The acid value of PBSA reflects the number of unreacted carboxylic acid groups at the end of the polybutylene succinate adipate molecular chain. The higher the acid value of PBSA, the more unreacted carboxylic acid groups at the end, and the relatively poorer hydrolytic stability. The present invention adopts PBSA with an acid value of ≤1.2 mgKOH / g, which has better hydrolytic stability, thereby improving the anti-aging performance of the biodegradable polymer composition.

[0023] As a preferred technical solution of the present invention, the biodegradable polymer composition comprises the following components in parts by weight:

[0024]

[0025] As a preferred technical solution of the present invention, the content of the dextrorotatory lactic acid structural unit relative to the polylactic acid is 0.2 to 1.8 mol%, more preferably 0.5 to 1.6 mol%, and particularly preferably 1.05 to 1.55%.

[0026] Preferably, the melt flow rate of the polylactic acid at 190°C and 2.16kg is 3.0 to 4.5 g / 10min, for example, 3.0 g / 10min, 3.2 g / 10min, 3.4 g / 10min, 3.6 g / 10min, 3.8 g / 10min, 4.0 g / 10min, 4.2 g / 10min, 4.4 g / 10min, 4.5 g / 10min or a range between any of the above values.

[0027] As a preferred technical solution of the present invention, the acid value of the polybutylene succinate adipate is ≤1.0 mgKOH / g.

[0028] Preferably, the melt flow rate of the polybutylene succinate adipate at 190° C. and 2.16 kg is 2.0 to 4.5 g / 10 min, for example, 2.0 g / 10 min, 2.2 g / 10 min, 2.4 g / 10 min, 2.6 g / 10 min, 2.8 g / 10 min, 3.0 g / 10 min, 3.2 g / 10 min, 3.4 g / 10 min, 3.6 g / 10 min, 3.8 g / 10 min, 4.0 g / 10 min, 4.2 g / 10 min, 4.4 g / 10 min, 4.5 g / 10 min or a range between any of the above values.

[0029] In the present invention, the melt flow rates of polylactic acid and polybutylene succinate adipate are tested according to the ASTM D1238-2010 standard method.

[0030] In the present invention, the inorganic filler may be an inorganic filler commonly used in the art. Optionally, the inorganic filler includes any one or a combination of at least two of talc, montmorillonite, kaolin, chalk, calcium carbonate, graphite, gypsum, conductive carbon black, calcium chloride, iron oxide, dolomite, wollastonite, titanium dioxide, silicate, mica, glass fiber, and mineral fiber.

[0031] Preferably, the inorganic filler includes any one of talc, mica, montmorillonite, and calcium carbonate, or a combination of at least two of them.

[0032] Preferably, the inorganic filler comprises talc.

[0033] Preferably, the talc has a lamellar structure.

[0034] Preferably, the diameter-to-thickness ratio of the talc is (25-90):1, for example 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1 or a range between any of the above values.

[0035] As a preferred technical solution of the present invention, talcum powder has a lamellar structure. Due to its lamellar structure and chemical composition, talcum powder dispersed in the PLA / PBSA matrix can better play the role of lubrication and bridging, making the two-phase distribution of PLA and PBSA more ideal, and the synergistic effect between PLA and PBSA is better, further improving the aging resistance of the biodegradable polymer composition. Other inorganic fillers with lamellar structures, such as mica, although having a lamellar structure, are difficult to play the role of lubrication and bridging brought by talcum powder.

[0036] In the present invention, the diameter-to-thickness ratio of talc powder can be obtained by the following method: talc powder is spread on a conductive adhesive, and after conductive treatment, the talc powder is placed in a scanning electron microscope (SEM, Guoyi Quantum Field Emission Scanning Electron Microscope SEM5000Pro) for morphological observation, the particle size and thickness of the talc powder are measured respectively, and the diameter-to-thickness ratio of the talc powder is calculated.

[0037] The inventors have found that by controlling the diameter-to-thickness ratio of talc within the range of (25-90):1, its lubrication and bridging effects are relatively better, so that the mechanical properties and aging resistance of the biodegradable polymer composition are better.

[0038] Preferably, the diameter-to-thickness ratio of the talc powder is (40-80):1.

[0039] In the present invention, the processing aid may be a conventional additive in the art.

[0040] Preferably, the processing aid comprises any one of an antioxidant, a plasticizer, a release agent, a surfactant, an antistatic agent, a dye, and a UV stabilizer, or a combination of at least two thereof.

[0041] In the present invention, the antioxidant includes but is not limited to at least one of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 164, antioxidant DLTP or antioxidant TPP; the plasticizer includes but is not limited to at least one of di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) or diethyl phthalate; the release agent includes but is not limited to at least one of fatty acid, paraffin, glycerol, vaseline, silicone oil, and polyethylene glycol; the surfactant includes but is not limited to at least one of long-chain alkyl quaternary ammonium salt and polyoxyethylene fatty alcohol ether; the UV stabilizer includes but is not limited to at least one of UV-531 and UV-292.

[0042] In a second aspect, the present invention provides a method for preparing the biodegradable polymer composition according to the first aspect, the preparation method comprising the following steps:

[0043] The biodegradable polymer composition is obtained by mixing polylactic acid, polybutylene succinate adipate, an inorganic filler and an optional processing aid, and then melt-extruding the mixture.

[0044] Preferably, the melt extrusion is carried out in an extruder.

[0045] Preferably, the extruder is a twin-screw extruder.

[0046] Preferably, the extrusion temperature is 140-240°C, for example, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, etc.

[0047] In a third aspect, the present invention provides a use of the biodegradable polymer composition as described in the first aspect in preparing degradable tableware.

[0048] Preferably, the degradable tableware includes degradable straws.

[0049] Preferably, the wall thickness of the degradable straw is 200-400 μm, for example, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, 400 μm, etc.

[0050] The degradable tableware prepared by using the biodegradable polymer composition provided by the present invention has good rigidity, toughness, low-temperature toughness and heat resistance, and has good resistance to wet and hot aging, and has a longer inventory period.

[0051] Compared with the prior art, the present invention has at least the following beneficial effects:

[0052] The invention compounded PLA and PBSA in specific weight proportions, with PLA as a continuous phase and PBSA as a dispersed phase, and under the synergistic effect of inorganic fillers, the molar content of PDLA in PLA and the acid value of PBSA were controlled within specific ranges, so that the prepared biodegradable polymer composition had excellent mechanical properties, good rigidity, toughness, low-temperature toughness and heat resistance, and could still maintain good mechanical properties after thermal aging. DETAILED DESCRIPTION

[0053] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0054] The sources of raw materials used in the embodiments and comparative examples of the present invention are as follows:

[0055] PLA-1, polylactic acid, Natureworks 4032D, the content of dextrorotatory lactic acid structural units is 1.5 mol%, and the melt flow rate at 190°C and 2.16 kg is 3.5 g / 10 min;

[0056] PLA-2, polylactic acid, Fengyuan FY801, the content of dextrorotatory lactic acid structural unit is 1 mol%, and the melt flow rate at 190℃ and 2.16kg is 3.9g / 10min;

[0057] PLA-3, polylactic acid, self-made (Zhuhai Jinfa Biology), KB600 NF10, the content of the right-handed lactic acid structural unit is 0.5 mol%, and the melt flow rate at 190 °C and 2.16 kg is 4.1 g / 10 min;

[0058] PLA-4, polylactic acid, Natureworks 4060D, the content of the right-handed lactic acid structural unit is 12 mol%, and the melt flow rate at 190 °C and 2.16 kg is 4.2 g / 10 min;

[0059] PLA-5, polylactic acid, Natureworks 4043D, the content of the right-handed lactic acid structural unit is 4.0 mol%, and the melt flow rate at 190 °C and 2.16 kg is 4.1 g / 10 min;

[0060] PBSA-1, poly(butylene adipate-co-butylene succinate), Zhuhai Jinfa Biology KB500, self-made, acid value is 0.8 mg KOH / g, and the melt flow rate at 190 °C and 2.16 kg is 3.0 g / 10 min;

[0061] PBSA-2, poly(butylene adipate-co-butylene succinate), Zhuhai Jinfa Biology KB500, self-made, acid value is 1.0 mg KOH / g, and the melt flow rate at 190 °C and 2.16 kg is 3.0 g / 10 min;

[0062] PBSA-3, poly(butylene adipate-co-butylene succinate), Zhuhai Jinfa Biology KB500, self-made, acid value is 1.2 mg KOH / g, and the melt flow rate at 190 °C and 2.16 kg is 3.0 g / 10 min;

[0063] PBSA-4, poly(butylene adipate-co-butylene succinate), Zhuhai Jinfa Biology KB500, self-made, acid value is 2.0 mg KOH / g, and the melt flow rate at 190 °C and 2.16 kg is 3.0 g / 10 min;

[0064] For PBSA, during the production process, the contents of the catalyst and the stabilizer are adjusted to obtain PBSA with different acid values. The PBSA-1 to PBSA-4 used in the present invention are all based on the PBSA with the brand name KB500 of Jinfa Biology, and different acid value products are self-made by slightly adjusting the contents of the catalyst and the stabilizer during the preparation process;

[0065] PBS: poly(butylene succinate), Zhuhai Jinfa Biology A200, acid value is 1.0 mg KOH / g, and the melt flow rate at 190 °C and 2.16 kg is 3.5 g / 10 min;

[0066] PBAT: polybutylene terephthalate adipate, Zhuhai Kingfa Biotechnology A400, acid value is 1.0 mgKOH / g, melt flow rate at 190°C and 2.16 kg is 3.7 g / 10 min;

[0067] Talc-1, Guangxi Longsheng AH-1250N6, batch A, diameter-to-thickness ratio of 60:1;

[0068] Talc-2, Guangxi Longsheng AH-1250N6, batch B, diameter-to-thickness ratio of 90:1;

[0069] Both talcum powder-1 and talcum powder-2 are products of Guangxi Longsheng AH-1250N6. Due to the different control processes of the manufacturers, different batches of talcum powder have different diameter-to-thickness ratios.

[0070] Talc-3, Dongguan Sanzhi TY90-13-A, diameter-to-thickness ratio is 25:1;

[0071] Montmorillonite, commercially available, diameter-to-thickness ratio of 60:1;

[0072] Mica, commercially available, diameter-to-thickness ratio 36:1;

[0073] Processing aid, antioxidant 1010, commercially available.

[0074] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. Unless otherwise specified, the reagents and materials used in the present invention are commercially available.

[0075] Examples 1 to 13

[0076] Examples 1 to 13 provide a biodegradable polymer composition, respectively. The amounts of the components are shown in Table 1 and Table 2. The preparation method is as follows:

[0077] PLA, PBSA, inorganic filler and optional processing aid are mixed and added to a twin-screw extruder at an extrusion temperature of 140-240° C. (wherein the temperature of the solid conveying zone is 120-150° C., the temperature of the melting zone is 170-210° C., and the temperature of the melt conveying zone is 210-220° C.), and the biodegradable polymer composition is obtained by melt mixing and extrusion granulation.

[0078] Table 1

[0079]

[0080] Table 2

[0081]

[0082] Comparative Examples 1 to 8

[0083] Comparative Examples 1 to 8 provide a biodegradable polymer composition, respectively. The amounts of the components are shown in Table 3. The preparation methods are as follows:

[0084] After mixing the components according to Table 3, the components were added to a twin-screw extruder at an extrusion temperature of 140-240° C. (wherein the temperature of the solid conveying zone was 120-150° C., the temperature of the melting zone was 170-210° C., and the temperature of the melt conveying zone was 210-220° C.), and the biodegradable polymer composition was obtained by melt mixing and extrusion granulation.

[0085] Table 3

[0086]

[0087] The biodegradable compositions provided in the examples and comparative examples were subjected to performance tests, and the test methods were as follows:

[0088] (1) The biodegradable composition is injection molded into a sample, and the tensile strength and the Izod notched impact strength after the injection molding are respectively detected; then the injection molded parallel comparison sample is aged at 60° C. and 60% RH for 15 days, and the tensile strength and the Izod notched impact strength after the aging treatment are detected, and the retention rates of the tensile strength and the Izod notched impact strength are respectively calculated; wherein:

[0089] Tensile strength: tested according to ISO 527-2-2012 standard method;

[0090] Izod notched impact strength: tested according to ASTM D256-2010 standard method.

[0091] (2) Extruding the biodegradable composition into a straw sample and testing the low-temperature toughness of the straw; wherein:

[0092] Low-temperature toughness: Place the straws at a freezing temperature of -15°C for 24 hours, and cross-squeeze the straws. If they do not break or become brittle, they are considered to have good low-temperature toughness. Select 50 straws, and if 1 breaks, record it as 1 / 50. Convert the result into a percentage of 0.2 / 10, marked as the broken straw ratio, and so on.

[0093] The performance test results are shown in Table 4.

[0094] Table 4

[0095]

[0096] It can be seen from Table 4 that the biodegradable polymer composition provided by the embodiment of the present invention has good rigidity (initial tensile strength ≥45MPa), toughness (initial Izod impact strength ≥3.9J / m) and low-temperature toughness (tube breakage ratio less than 2.0 / 10), and can still maintain good mechanical properties after thermal aging (tensile strength retention rate ≥73%, Izod impact strength retention rate ≥30%).

[0097] Comparative Example 1 does not contain PBSA, and the rigidity of the obtained biodegradable polymer composition is too strong, and the toughness and low-temperature toughness are significantly poor; in Comparative Examples 2 and 3, the amounts of PLA and PBSA exceed the range specified in the present invention, which also makes the rigidity and toughness of the biodegradable polymer composition unbalanced; the PBSA content is high, the PLA content is low, and the initial tensile strength is low; the PBSA content is low, the PLA content is high, and the notched impact strength is low.

[0098] In Comparative Examples 4-5, the content of the dextrorotatory lactic acid structural unit in the polylactic acid in the PLA is too high, resulting in serious deterioration of the mechanical properties of the biodegradable composition after aging, and poor rigidity and low-temperature toughness.

[0099] The acid value of PBSA in Comparative Example 6 is too high, resulting in poor aging resistance of the biodegradable polymer composition.

[0100] In Comparative Example 7, PBSA was replaced with PBS in an equal weight portion, resulting in a significant deterioration in the low-temperature toughness of the biodegradable polymer composition; in Comparative Example 8, PBSA was replaced with PBAT in an equal weight portion, resulting in a significant deterioration in the low-temperature toughness of the biodegradable polymer composition.

[0101] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the biodegradable polymer composition of the present invention and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A biodegradable composition, characterized in that The biodegradable composition comprises the following components in parts by weight: The molecular structure of the polylactic acid comprises a L-lactic acid structural unit and a D-lactic acid structural unit; the content of the D-lactic acid structural unit relative to the polylactic acid is 0.1 to 2 mol%; The acid value of the polybutylene succinate adipate is ≤1.2 mgKOH / g.

2. The biodegradable composition according to claim 1, characterized in that The biodegradable composition comprises the following components in parts by weight:

3. The biodegradable composition according to claim 1, characterized in that The content of the dextrorotatory lactic acid structural unit relative to the polylactic acid is 0.2 to 1.8 mol%.

4. The biodegradable composition according to claim 1, characterized in that The acid value of the polybutylene succinate adipate is ≤1.0 mgKOH / g.

5. The biodegradable composition according to claim 1, characterized in that The inorganic filler includes any one of talc, mica, montmorillonite and calcium carbonate, or a combination of at least two of them.

6. The biodegradable composition according to claim 5, characterized in that The inorganic filler includes talc.

7. The biodegradable composition according to claim 6, characterized in that The talc has a lamellar structure; Preferably, the diameter-to-thickness ratio of the talc powder is (25-90):

1.

8. The biodegradable composition according to claim 1, characterized in that The processing aids include any one of antioxidants, plasticizers, mold release agents, surfactants, antistatic agents, dyes, and UV stabilizers, or a combination of at least two of them.

9. A method for preparing a biodegradable composition according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: The polylactic acid, polybutylene succinate adipate, inorganic filler and optional processing aid are mixed and melt-extruded to obtain the biodegradable composition.

10. Use of the biodegradable composition according to any one of claims 1 to 8 in preparing degradable tableware.

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