Degradable plastic bottles and their manufacturing method and decomposition process

Abstract

To provide a decomposable plastic bottle, and a manufacturing method and a decomposition process thereof.SOLUTION: A decomposable plastic bottle is obtained by blow-molding a decomposable composition material. The decomposable composition material is obtained by smelting / extrusion-molding a resin mixture. The composition of the resin mixture is as follows: PLA of 10 to 60 pts.wt., PBAT of 20 to 50 pts.wt., PPC of 0.5 to 20 pts.wt., PGA of 0.5 to 20 pts.wt., and calcium carbonate of 1 to 10 pts.wt. The crystallinity of PLA is improved by the addition of PPC, and then the degree of crystallization of PLA is improved by the nucleation action of PGA, and thereby the barrier effect against organic solvents on the bottle for agricultural chemicals is improved, and the possibility that the ingredients of the agricultural chemicals run off is reduced. The decomposable plastic bottle is advantageous for the long-term storage of the agricultural chemicals.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present application relates to the field of plastic product technology, more specifically, it relates to a degradable plastic bottle and its manufacturing method and decomposition process. [Background technology]

[0002] As the accumulation of waste plastic becomes increasingly serious, the application of biodegradable materials has attracted more and more attention. One of the effective ways to reduce the accumulation of waste plastic is to use degradable materials to produce various plastic products, and then adopt corresponding recovery and decomposition processes to render the recovered degradable plastic products harmless.

[0003] In the related art, a degradable plastic bottle for agricultural chemicals is manufactured by blow molding a blend of polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), the composition of the blend includes 10-60 parts by weight of PLA, 20-50 parts by weight of PBAT, and 1-10 parts by weight of calcium carbonate, the blend is manufactured by the following method: (1) mixing calcium carbonate, PBAT, and PLA to obtain a resin mixture, melt processing the resin mixture to obtain a melt, and (2) extruding the melt to obtain a degradable composition material. By blending PBAT with PLA, PBAT can improve the toughness of PLA, which is helpful in improving the mechanical performance of the agricultural chemical bottle.

[0004] Regarding the above-mentioned related art, the inventors believe that, although the PBAT in the related art improves the mechanical performance of PLA, the benzene ring in the PBAT molecular chain destroys the regularity of the PLA molecular chain, and reduces the crystallinity of PLA. Many existing pesticide products contain organic solvents, and the reduced crystallinity of PLA reduces the barrier effect of pesticide bottles against organic solvents, making it difficult to meet the storage period requirements of existing pesticide products, which is disadvantageous for long-term storage of pesticide products. Summary of the Invention [Problem to be solved by the invention]

[0005] In the related art, PBAT causes a decrease in the crystallinity of PLA, so that the degradable plastic bottle for pesticides is difficult to meet the requirements for the storage period of existing pesticide products, which is disadvantageous for long-term storage of pesticides. In order to improve this shortcoming, the present application provides a degradable plastic bottle and its manufacturing method and decomposition process. [Means for solving the problem]

[0006] In a first aspect, the present application provides a degradable plastic bottle, and adopts the following technical solutions:

[0007] A degradable plastic bottle, the degradable plastic bottle being obtained by blowing a degradable composition material, the degradable composition material being obtained by smelting and extruding a resin mixture, the resin mixture comprising, by weight, 10-60 parts polylactic acid, 20-50 parts polybutylene adipate terephthalate, 0.5-20 parts polypropylene carbonate (PPC), 0.5-20 parts polyglycolic acid (PGA), and 1-10 parts calcium carbonate.

[0008] By adopting the above technical solution, compared with the related art, the present application adds PPC and PGA to the resin mixture. PPC is more compatible with PLA than PBAT is with PLA, so it is easy to disperse uniformly in PLA. In the molten state, PPC in PLA plays the role of a solvent, which is favorable for the segment rearrangement of PLA and improves the crystallinity of PLA. In addition to improving the crystallinity of PLA, PGA can play a nucleation role in the PLA crystallization process, which improves the crystallinity of PLA, thereby helping to improve the barrier effect of degradable plastic bottles against organic solvents.

[0009] When the degradable plastic bottle of the present application contains liquid pesticides, the organic solvents in the pesticide are less likely to pass through the bottle walls, thereby reducing the possibility of the ingredients in the pesticide being washed away, realizing the successful application of degradable materials in the production of pesticide bottles and advantageous for the long-term storage of pesticides.

[0010] Preferably, the resin mixture comprises, by weight, 20-50 parts PLA, 30-40 parts PBAT, 5-15 parts PPC, 5-15 parts PGA, and 3-7 parts calcium carbonate.

[0011] By adopting the above technical solutions, the compounding ratio of the resin mixture can be optimized, which helps to improve the barrier effect of degradable plastic bottles against organic solvents.

[0012] Preferably, the resin mixture composition further comprises 0.5-20 parts by weight of polybutylene succinate (PBS).

[0013] By adopting the above technical solution, a blend having better impact strength than PLA can be produced after blending PBS and PLA, which can improve the resistance effect of degradable plastic bottles against external impact and help reinforce the drop resistance of degradable plastic bottles.

[0014] Preferably, the resin mixture composition further comprises 0.5-20 parts by weight of polycaprolactone (PCL).

[0015] By adopting the above technical solution, the addition of PCL reduces the brittleness of PBS, and PCL further improves the compatibility of PLA and PBAT, and improves the phase interface between PBAT and PLA. The combined effect of improving the phase interface and improving the compatibility of PLA and PBAT further improves the drop resistance of degradable plastic bottles.

[0016] Preferably, the PLA composition includes at least one of poly-L-lactic acid (PLLA) and poly-D-lactic acid (PDLA).

[0017] By adopting the above technical solution, PLLA and PDLA are a pair of enantiomers of PLA, and when the composition of PLA contains PLLA and PDLA at the same time, PLLA and PDLA will generate stereocomplex crystals when melt-blended, and the molecular chain stacking of the stereocomplex crystals is tighter than that of PLLA crystals and PDLA crystals. Moreover, the formation of stereocomplex crystals improves the order of PLA, thereby compensating for the order lost by PBAT of PLA, and reducing the adverse effect of PBAT on the crystallinity of PLA. Therefore, the PLA containing PLLA and PDLA at the same time can have a higher crystallinity when processed and molded, which is helpful in improving the barrier effect of degradable plastic bottles against organic solvents.

[0018] Preferably, the weight ratio of PDLA to PLLA in said PLA is 1:(0.8-1.2).

[0019] By adopting the above technical solution, the weight ratio of PDLA and PLLA is optimized, and when the contents of PDLA and PLLA are close to each other, it is favorable for the formation of stereocomplex crystals in PLA. The increase in the content of stereocomplex crystals improves the crystallinity of PLA, which is helpful in improving the barrier effect of degradable plastic bottles against organic solvents.

[0020] Preferably, the average molecular weight of the PLLA is 1000-4200.

[0021] By adopting the above technical solution, when the average molecular weight of PLLA is too large, PLLA and PDLA do not produce stereo crystals but are prone to form homo crystals; therefore, the present application optimizes the average molecular weight of PLLA, which is favorable for the formation of stereocomplex crystals within this range, thereby improving the crystallization degree of PLA and improving the barrier effect of degradable plastic bottles against organic solvents.

[0022] Preferably, the average molecular weight of the PDLA is 1,000-20,000.

[0023] By adopting the above technical solution, when the average molecular weight of PDLA is too large, PLLA and PDLA are similarly likely to form homocrystals rather than stereocrystals; therefore, the present application further optimizes the average molecular weight of PDLA, which is favorable to the formation of stereocomplex crystals, improves the crystallinity of PLA, and is favorable to improving the barrier effect of degradable plastic bottles against organic solvents.

[0024] In addition, some auxiliary components may be further added to the resin mixture of the present application to improve performance, such as modified starch, talc powder and composite crosslinker (composite of pectin and nano-organic bentonite).

[0025] In a second aspect, the present application provides a resin mixture for producing a degradable material, and adopts the following technical solutions:

[0026] The resin mixture comprises, in parts by weight, 10-60 parts polylactic acid, 20-50 parts polybutylene adipate terephthalate, 0.5-20 parts polypropylene carbonate, 0.5-20 parts polyglycolic acid, and 1-10 parts calcium carbonate.

[0027] Preferably, the resin mixture comprises, by weight, 20-50 parts polylactic acid, 30-40 parts polybutylene adipate terephthalate, 5-15 parts polypropylene carbonate, 5-15 parts polyglycolic acid, and 3-7 parts calcium carbonate.

[0028] Preferably, the resin mixture further comprises 0.5-20 parts by weight of polybutylene succinate.

[0029] Preferably, the resin mixture further comprises 0.5-20 parts by weight of polycaprolactone.

[0030] Preferably, the polylactic acid includes at least one of poly-L-lactic acid and PDLA.

[0031] Preferably, the weight ratio of PDLA to poly-L-lactic acid in the polylactic acid is 1:(0.8-1.2).

[0032] Preferably, the average molecular weight of the poly(L-lactic acid) is 1000-4200.

[0033] Preferably, the average molecular weight of the PDLA is 1,000-20,000.

[0034] In a third aspect, the present application provides a method for producing a degradable plastic bottle, and adopts the following technical solutions:

[0035] The manufacturing method of degradable plastic bottles is as follows: Step (1) of melting the resin mixture at 100-400°C and extruding it to obtain a degradable composition material; and step (2) of blow molding the degradable composition material of step (1) at 60-160°C to obtain a degradable plastic bottle.

[0036] By adopting the above technical solution, the present application first melts the resin mixture, then obtains a degradable composition material by extrusion molding, and then blow molds it under a medium to low temperature condition of 60-160°C to obtain a degradable plastic bottle.

[0037] In a fourth aspect, the present application provides a decomposition process for degradable plastic bottles, and adopts the following technical solutions:

[0038] The decomposition process of degradable plastic bottles is as follows: A step (1) of collecting and crushing the degradable plastic bottles to obtain crushed material; and (2) mixing the ground material and compost in a weight ratio of (20-80):(80-20), subsequently putting them into a breathable bag, and further burying the breathable bag in compost at 50-65°C, and then waiting for 145-180 days, after which the breathable bag is removed, thereby completing the decomposition of the degradable plastic bottles.

[0039] By adopting the above technical solution, each organic composition in the degradable plastic bottle of the present application is a degradable material. When actually carrying out the decomposition process according to the method of the present application, the recovered degradable plastic bottle is first crushed to obtain a crushed material. Then, the present application optimizes the weight ratio range for mixing the crushed material and compost, and according to this mass ratio, the decomposition can be completed by composting at 50-65°C for 14-20 days. Effect of the Invention

[0040] As described above, the present application has at least one of the following beneficial effects.

[0041] 1. This application adds PPC and PGA to the raw material system of degradable plastic bottles, improves the crystallinity of PLA through PPC, and then improves the crystallinity of PLA through the nucleation action of PGA, improving the barrier effect of pesticide bottles against organic solvents and reducing the possibility of pesticide ingredients leaking out, thereby realizing the successful application of degradable materials in the production of pesticide bottles, and benefiting the long-term storage of pesticides.

[0042] 2. In the present application, the PLA composition preferably contains at least one of PLLA and PDLA. When the PLA composition contains both PLLA and PDLA, the PLLA and PDLA form stereocomplex crystals when melt-blended, thereby improving the crystallization degree of PLA and the barrier effect of degradable plastic bottles against organic solvents. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] The present invention will be described in more detail below with reference to examples, preparation examples and comparative examples, and the raw materials used in the present invention are all commercially available. EXAMPLES

[0044] (Examples 1 to 5) The following description will be given taking the first embodiment as an example.

[0045] Example 1 This embodiment provides a degradable plastic bottle obtained by blow processing a degradable composition material, and the degradable composition material is obtained by smelting and extrusion molding a resin mixture, and the resin mixture contains, by weight, 10 kg of PLA, 20 kg of PBAT, 0.5 kg of PPC, 0.5 kg of PGA, and 1 kg of calcium carbonate, where the PLA is PLLA with an average molecular weight of 5000.

[0046] In this embodiment, the degradable plastic bottle is manufactured by the following steps: (1) Melting the resin mixture at 240°C and extruding it to obtain a degradable composition material; (2) The degradable composition of step (1) was subjected to blow molding at 70° C. to obtain a degradable plastic bottle.

[0047] As shown in Table 1, the main difference between Examples 1 to 5 is the raw material blend ratio of the resin mixture.

[0048] The present embodiment further provides a decomposition process for a decomposable plastic bottle, comprising the steps of: (1) Degradable plastic bottles are collected and crushed to obtain crushed material. (2) The ground material and compost raw materials were mixed in a weight ratio of 80:20, then placed in a breathable bag, and the breathable bag was then buried in a compost layer at 60°C. After waiting for 150 days, the breathable bag was removed, completing the decomposition of the degradable plastic bottles. In this step, the compost raw materials were made by mixing pig manure, corn straw, and wood ash in a weight ratio of 4:6:1.

[0049] [Table 1] Table 1. Raw material composition of resin mixture JPEG0007618150000001.jpg49131

[0050] Example 6 The difference between this example and Example 4 is that the composition of the resin mixture further contains 0.5 kg of PBS.

[0051] As shown in Table 2, Examples 6 to 10 differ in the amount of PBS used.

[0052] [Table 2] Table 2. Amount of PBS used JPEG0007618150000002.jpg21128

[0053] Example 11 The difference between this example and Example 9 is that the composition of the resin mixture further contains 0.5 kg of PCL.

[0054] As shown in Table 3, Examples 11 to 15 differ in the amount of PCL used.

[0055] [Table 3] Table 3 PCL usage JPEG0007618150000003.jpg21128

[0056] (Example 16) The difference between this example and Example 4 is that the PLA used is PDLA with an average molecular weight of 20,000.

[0057] (Example 17) The difference between this embodiment and embodiment 4 is that PLA is prepared by mixing PDLA having an average molecular weight of 5000 and PDLA having an average molecular weight of 24000 in a weight ratio of 1:0.6.

[0058] As shown in Table 4, the difference between Examples 17-21 is the weight ratio of PDLA to PLLA.

[0059] [Table 4] Table 4 Weight ratio of PDLA and PLLA JPEG0007618150000004.jpg26128

[0060] As shown in Table 5, Examples 22-25 differ from Example 19 in that the average molecular weight of PLLA is different.

[0061] [Table 5] Table 5. Average molecular weight of PLLA JPEG0007618150000005.jpg26128

[0062] As shown in Table 6, Examples 26-29 differ from Example 24 in that the average molecular weight of PDLA is different.

[0063] [Table 6] Table 6. Average molecular weight of PDLA JPEG0007618150000006.jpg21128 comparative example

[0064] Comparative Example 1 The degradable plastic pesticide bottle is manufactured by blow molding a blend of PBAT and PLA at 160°C, the composition of the blend includes 50 kg of PLA (specifically PLLA with an average molecular weight of 5500), 40 kg of PBAT and 5 kg of calcium carbonate, and the blend is manufactured by the following method: (1) Mixing calcium carbonate, PBAT and PLA to obtain a resin mixture, and melt processing the resin mixture at 200°C to obtain a melt; (2) The melt was extruded to obtain a degradable composition material.

[0065] Comparative Example 2 The difference between this comparative example and Example 4 is that the resin mixture does not contain PPC.

[0066] Comparative Example 3 The difference between this comparative example and Example 4 is that the resin mixture does not contain PGA.

[0067] Performance inspection test method 1. Barrier performance The barrier property of the degradable plastic bottle was tested with reference to the ASTM D2684-1995 standard of the American Society for Testing and Materials. The ratio of the permeability of each Example and Comparative Example to Comparative Example 1 was then calculated. The ratio value was recorded as the relative permeability, and the results are shown in Table 7.

[0068] With reference to the description in "BB / T0044-2007 Packaging Containers Plastic Bolts for Pesticides," the leakage amount (thermal storage weight loss) and airtightness performance were verified for all examples, and the results are shown in Table 8.

[0069] [Table 7] Table 7 Relative permeability JPEG0007618150000007.jpg9077

[0070] [Table 8] Table 8. Airtightness and leakage detection results JPEG0007618150000008.jpg186128

[0071] 2. Drop performance Using 15 degradable plastic bottles of the same embodiment as samples, a test was conducted with reference to the drop performance test method described in "BB / T0044-2007 Packaging Containers Agricultural Chemical Plastic Bottles." During the test, the degradable plastic bottles were dropped and the test was repeated until the plastic bottles broke and leaked. After the test for one set of samples was completed, the average number of drops corresponding to the time when the samples in the set broke and leaked was calculated. After the calculation of the average values ​​was completed, the ratio of the measured average value of each set of samples to the measured average value of Example 4 was calculated and recorded as the relative drop performance. The calculation results of the relative drop performance are shown in Table 9.

[0072] In addition, a drop performance test was conducted for all the examples according to the five drop tests specified in "BB / T0044-2007 Packaging Containers Plastic Bottles for Agricultural Chemicals." The results are shown in Table 10.

[0073] [Table 9] Table 9 Relative drop performance JPEG0007618150000009.jpg9046

[0074] [Table 10] Table 10 Drop performance (5 times) JPEG0007618150000010.jpg183128

[0075] 3. Axial pressure resistance, internal pressure resistance Referring to the description in "BB / T0044-2007 Packaging Containers - Plastic Bottles for Pesticides," the axial pressure resistance and internal pressure resistance were tested, and the results are shown in Table 11.

[0076] [Table 11] Table 11 Axial and internal pressure resistance JPEG0007618150000011.jpg183148

[0077] 4. Decomposition performance Based on "ISO 14855-1:2012 Determination of the ultimate aerobic biodegradability of plastic materials under controlled composting conditions-Method by analysis of evolved carbon dioxide-Part 1:General method" and "GB / T 19277.1-2011 Determination of the ultimate aerobic biodegradability of materials under controlled composting conditions - Method by analysis of evolved carbon dioxide - Part 1:General method", a degradable plastic bottle was tested for its degradability. The average test period was 147 days, and the judgment included the following three items: (1) Biodegradation rate of the reference material after 45 days > 71.0%; (2) the relative deviation of the biodegradation percentage of the reference material in different containers at the end of the test is <20%; (3) The average amount of carbon dioxide generated in the blank container within the 10 days prior to the test is 50-150 mg of CO2 / g of volatile solids. The results are shown in Table 12.

[0078] [Table 12] Table 12. Judgment results of decomposition performance JPEG0007618150000012.jpg138128

[0079] Five, appearance quality The appearance quality was inspected based on the description of "BB / T0044-2007 Packaging Containers Plastic Bolts for Pesticides" and the judgment contents included the following six items: (1) The deviation of the inner diameter of the bottle mouth is within ±0.40 mm. (2) The deviation of the outer diameter of the bottle mouth is within ±0.40 mm. (3) The height deviation is within ±1.5 mm. (4) Squareness deviation ≦4.5mm; (5) The ratio of the minimum thickness to the thickness of the symmetrical portion is ≦1.3; (6) Mass deviation is within ±5%. The results are shown in Table 13.

[0080] [Table 13] Table 13. Appearance quality evaluation results JPEG0007618150000013.jpg183128

[0081] As can be seen from Examples 1-5 and Comparative Example 1 in conjunction with Table 7, the relative leakage rates measured in Examples 1-5 are all smaller than Comparative Example 1, which indicates that the present application improves the crystallinity of PLA by adding PPC, improves the crystallinity of PLA through the nucleation action of PGA, and improves the barrier effect of pesticide bottles against organic solvents. The degradable plastic bottle of the present application not only meets the technical indicators of conventional pesticide bottles, but can also store pesticides for a longer period of time without leakage compared to conventional pesticide bottles, which is advantageous for long-term storage of pesticides. In Examples 1-5, the PLA content of Example 4 is relatively high, so the effect of improving the PLA crystallinity is significant, and therefore the permeation resistance of Example 4 is relatively high.

[0082] As can be seen from Example 3 and Comparative Example 2-3 in combination with Table 7, when the resin mixture lacks PPC, even though PGA can exert a nucleation effect, the improvement of the crystallinity of PLA is not significant. When the resin mixture lacks PGA, even though PPC improves the crystallinity of PLA by promoting the segment rearrangement of PLA, the improvement of the crystallinity of PLA is relatively limited.

[0083] As can be seen from Examples 1-29 and Table 8, the degradable plastic bottles of the examples of the present application meet the relevant regulations for airtightness and leakage in the prior art index.

[0084] As can be seen from Examples 4 and 6-10 in combination with Table 9, the addition of PBS to the resin mixture can improve the drop performance of degradable plastic bottles, and the drop performance is further improved with the increase in the amount of PBS added. However, it was found that the improvement in drop performance is not a linear increase process with the increase in the amount of PBS added, and after the amount of PBS added exceeds 20 parts, the improvement in drop performance is relatively small when PBS is continued to be added. In order to fully save raw materials, control costs, and achieve good performance, it is preferable that the amount of PBS added is 0.5-20 parts.

[0085] As can be seen from Example 9, Examples 11-15 and Table 7, when PBS is added, the addition of PCL to the resin mixture can further improve the drop performance of degradable plastic bottles. With the increase in the amount of PCL added, the drop performance is also improved, but with the increase in the amount of PCL added, the improvement in drop performance is not a linear increase process. It was found that after the amount of PCL added exceeds 20 parts, the improvement in drop performance is relatively small when PCL is continued to be added. In order to fully save raw materials, control costs, and achieve good performance, it is preferable that the amount of PBS added is 0.5-20 parts.

[0086] As can be seen from Examples 4 and 16 in conjunction with Table 7, after replacing PLLA with PDLA, the molecular weight increases, so the crystallinity of PLA decreases, and the barrier effect of the degradable plastic bottle against organic solvents decreases.

[0087] As can be seen from Examples 4, 16, 17-21 and Table 7, the blend of PLLA and PLLA produces stereocomplex crystals in the degradable plastic bottle, improving the barrier effect of the degradable plastic bottle against organic solvents. In addition, when the ratio of the amount of PLLA to PDLA used is within the range of 1:(0.8-1.2), the barrier effect of the degradable plastic bottle against organic solvents is high, which is advantageous for long-term storage of pesticides.

[0088] As can be seen from Examples 19, 22-29 and Table 7, the average molecular weight of PLLA and PDLA in the appropriate range is favorable for the formation of stereocrystals and favorable for improving the barrier effect of degradable plastic bottles against organic solvents. When the average molecular weight of PLLA is greater than 4200 and the molecular weight of PDLA is greater than 20000, the barrier effect of degradable plastic bottles against organic solvents is relatively not so significant.

[0089] As can be seen from Examples 1-29 and Tables 10-13, the degradable plastic bottles of the examples of the present application meet the relevant requirements for drop performance, axial pressure resistance, internal pressure resistance, degradability, and appearance quality in the prior art indexes.

[0090] The specific examples are merely interpretations of the present application and are not intended to limit the present application. Those skilled in the art may, after reading this specification, make modifications to the present examples as necessary without making any creative contribution thereto, but as long as they are within the scope of the claims of the present application, they will be protected by the Patent Law.

Claims

1. A degradable plastic bottle obtained by blow processing a degradable composition material, the degradable composition material being obtained by smelting and extrusion molding a resin mixture, the resin mixture comprising, by weight, 10-60 parts of polylactic acid, 20-50 parts of polybutylene adipate terephthalate, 0.5-20 parts of polypropylene carbonate, 0.5-20 parts of polyglycolic acid, and 1-10 parts of calcium carbonate; The polylactic acid contains poly-D-lactic acid (PDLA) and poly-L-lactic acid (PLLA), and the weight ratio of PDLA to PLLA in the polylactic acid is 1:(0.6-1.2); The average molecular weight of the PLLA is 1000-5000; The average molecular weight of the PDLA is 1,000-24,000. A degradable plastic bottle.

2. The degradable plastic bottle according to claim 1, characterized in that the resin mixture comprises, by weight, 20-50 parts of polylactic acid, 30-40 parts of polybutylene adipate terephthalate, 5-15 parts of polypropylene carbonate, 5-15 parts of polyglycolic acid, and 3-7 parts of calcium carbonate.

3. 2. The degradable plastic bottle according to claim 1, wherein the resin mixture further comprises 0.5-20 parts by weight of polybutylene succinate.

4. 4. The degradable plastic bottle according to claim 3, wherein the resin mixture further comprises 0.5-20 parts by weight of polycaprolactone.

5. The composition, by weight, is 10-60 parts polylactic acid, 20-50 parts polybutylene adipate terephthalate, 0.5-20 parts polypropylene carbonate, 0.5-20 parts polyglycolic acid, and 1-10 parts calcium carbonate. The polylactic acid contains poly-D-lactic acid (PDLA) and poly-L-lactic acid (PLLA), and the weight ratio of PDLA to PLLA in the polylactic acid is 1:(0.6-1.2); The average molecular weight of the PLLA is 1000-5000; The average molecular weight of the PDLA is 1,000-24,000. A resin mixture for producing a degradable material, comprising:

6. The resin mixture for producing a degradable material according to claim 5, characterized in that the resin mixture comprises, by weight, 20-50 parts of polylactic acid, 30-40 parts of polybutylene adipate terephthalate, 5-15 parts of polypropylene carbonate, 5-15 parts of polyglycolic acid, and 3-7 parts of calcium carbonate.

7. The resin mixture for producing a degradable material according to claim 5, characterized in that the resin mixture further comprises 0.5-20 parts by weight of polybutylene succinate.

8. The resin mixture for producing a degradable material according to claim 7, characterized in that the resin mixture further comprises 0.5-20 parts by weight of polycaprolactone.

9. Step (1) of melting a resin mixture to produce the decomposable material according to any one of claims 5 to 8 under the condition of 100-400°C, and obtaining a decomposable composition material after extrusion molding; and step (2) of blow molding the degradable composition material of step (1) at 60-160° C. to obtain a degradable plastic bottle.

10. A step (1) of collecting and crushing the degradable plastic bottle according to any one of claims 1 to 4 to obtain a crushed product; and (2) mixing the ground material and compost in a weight ratio of (20-80):(80-20), then putting the mixture into a breathable bag, burying the breathable bag in compost at 50-65°C, and waiting for 145-180 days before removing the breathable bag, thereby completing the decomposition of the decomposable plastic bottle.

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