Blended membrane capable of degrading PBAT and starch and preparation method of blended membrane

Abstract

The invention discloses a degradable PBAT and starch blend membrane and a preparation method thereof. The preparation method comprises the following steps: a, starch extraction: preparing potato starch from potato peel; b, microcapsule preparation; c, gelatinizing; d, blending with the PBAT; and e, forming a film: adding glycerol and essential oil microcapsule powder into the starch aqueous solution according to a mass ratio of the glycerol to the potato starch of (0.4-0.6): 1 and a mass ratio of the essential oil microcapsule powder to the potato starch of (0.1-0.5): 1 to form a mixture A, adding PBAT into the mixture A according to a mass ratio of PBAT to the potato starch of 12: 5, stirring to obtain a mixture B, carrying out tape casting, drying at room temperature for 24-72 hours, and uncovering the film. According to the invention, the toughness, antibacterial property and high temperature resistance of the film are remarkably improved through the synergistic effect of a beta-cyclodextrin inclusion technology and glycerol plastification; the tensile strength of the obtained PBAT and starch blend film reaches 26.6-28.2 MPa, the 30-day natural degradation rate exceeds 60%, and the PBAT and starch blend film is remarkable in fruit and vegetable fresh-keeping effect, is suitable for the fields of food packaging, degradable mulching films and the like, and has environmental protection property and function expansion property.

Description

Technical Field

[0001] The present invention relates to the field of biodegradable materials, and in particular to a degradable PBAT and starch blend film and a preparation method thereof. Background Art

[0002] The rapid development of the plastics industry has led to an increasingly severe global plastic pollution problem. Traditional plastics are derived from fossil fuels, emit significant amounts of greenhouse gases during production, and take hundreds of years to degrade in the wild, ultimately forming microplastic particles that contaminate soil and water, reducing land productivity. Therefore, the development of fully biodegradable bio-based alternatives to traditional plastics has become a pressing global environmental challenge.

[0003] Polylactic acid (PLA) is currently the most widely used biodegradable material. Although it has the advantage of renewable sources (such as corn starch), its defects seriously restrict its practical application: harsh degradation conditions: it requires an industrial composting environment (temperature ≥ 58°C, humidity > 60%), and its degradation rate in natural soil is extremely low; insufficient mechanical properties: the tensile strength is generally lower than 30MPa, and the heat resistance temperature is only 50-60°C, which cannot meet the requirements of food heat-sealed packaging or wind-resistant ground film; high cost: the raw materials rely on food crops, and the production cost is 2-3 times that of traditional PE film, making it difficult to promote on a large scale. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a preparation method of a PBAT and starch blend film and a preparation method thereof to solve the above-mentioned technical problems.

[0005] A method for preparing a degraded PBAT and starch blend film comprises the following steps:

[0006] a. Starch extraction: potato peels were mixed with deionized water in a mass ratio of 1: (1.5-3), stirred at 20-30 ° C and 180-220 rpm for 0.5-1.5 hours, and the solid and liquid were separated through a 50-100 μm sieve. The filtrate was dried to obtain potato starch;

[0007] b. Microcapsule Preparation: The essential oil and anhydrous ethanol were mixed in a mass ratio of 1: (4-12) to form a stable essential oil solution, the solution was stirred with β-cyclodextrin in a mass ratio of 1: (8-15) at 40-50 ° C for 20-40 minutes, refrigerated for 12-36 hours to complete the inclusion, filtered, and dried to obtain essential oil microcapsule powder;

[0008] c. Gelatinization: Mix potato starch, sodium carboxymethyl cellulose and deionized water in a mass ratio of 1:(0.4-0.6):(30-45) and gelatinize at 75-95°C to form a starch aqueous solution;

[0009] d. Film Formation: Glycerol and essential oil microcapsule powder are added to the starch aqueous solution, with the mass ratio of glycerol to potato starch being 0.4-0.6:1, and the mass ratio of essential oil microcapsule powder to potato starch being 0.1-0.5:1, to form a mixed solution A. PBAT is added to the mixed solution A, with the mass ratio of PBAT to potato starch being 12:5, to form a mixture B. Mixture B is placed at 140-150°C and a rotation speed of 300-500 r / min, stirred, and then cast into a film. The film is dried at room temperature for 24-72 hours and then removed.

[0010] Furthermore, in step d, glycerin is added dropwise to the gelatinized liquid at 70-80° C., followed by essential oil microcapsule powder.

[0011] Furthermore, the glycerol in step d is added dropwise in 2-4 times, with an addition interval of 3-10 minutes.

[0012] Furthermore, the plant essential oil in step b is thyme essential oil, eugenol or camphor leaf essential oil.

[0013] Furthermore, in step a, potato peels are mixed with deionized water in a mass ratio of 1:2, stirred at room temperature and 200 rpm for 1 hour, the solid and liquid are separated through an 80 μm sieve, and the filtrate is decanted, filtered, and dried to obtain potato starch.

[0014] Furthermore, in step b, the plant essential oil and anhydrous ethanol are mixed in a mass ratio of 1:(5-10) to form a stable essential oil solution, the solution is stirred with β-cyclodextrin in a mass ratio of 1:(5-12) at 45° C. for 30 minutes, refrigerated for 24 hours to complete inclusion, and then filtered and dried at 60° C. for 3 hours to obtain essential oil microcapsule powder.

[0015] Furthermore, in step c, potato starch, sodium carboxymethyl cellulose and deionized water are mixed in a mass ratio of 1:0.5:(32-40), and gelatinized at 80-90° C. to form a starch aqueous solution.

[0016] Furthermore, in step d, glycerol and essential oil microcapsule powder are added to the gelatinized liquid, the mass ratio of glycerol to potato starch is 0.5:1, and the mass ratio of essential oil microcapsule powder to potato starch is (0.2-0.4):1 to form a mixed solution A, PBAT is added to the mixed solution A, the mass ratio of PBAT to potato starch is 12:5 to form a mixture B, and the mixture B is placed at 140-150°C and a speed of 300-500r / min. After stirring until it becomes viscous, it is cast onto a plastic plate and dried at room temperature for 48 hours before peeling off the film.

[0017] Furthermore, the method further comprises adding Au:AgNPs in step c, wherein the Au:Ag NPs are mixed with deionized water at a mass ratio of 0.001-0.5:100.

[0018] Furthermore, a PBAT and starch blend film prepared by the above method is provided, wherein the tensile strength is ≥25 MPa and the weight loss rate under natural environment for 30 days is >60%.

[0019] Furthermore, an application of the above-mentioned PBAT and starch blend film is provided, wherein the PBAT and starch blend film is suitable for food wrap, degradable ground film or medical packaging material.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention integrates potato peel resource utilization, microcapsule sustained release, and antibacterial nanoparticle synergistic enhancement technology to produce a PBAT and starch blend film with enhanced mechanical properties and significantly improved heat resistance. Through efficient raw material utilization and process optimization, costs are significantly reduced, potato peel waste is fully utilized, and raw material costs are reduced by 35%. No toxic crosslinking agents are required throughout the process, significantly reducing energy consumption. The microcapsules impart broad-spectrum antimicrobial properties to the film, extending the sustained release period of the microcapsules in the PBAT and starch blend film and reducing volatile losses. The addition of Au:Ag NPs results in an antibacterial rate exceeding 99.9%. By optimizing the entire process parameters, including glycerol addition, starch extraction, microencapsulation, gelatinization, and film-forming parameters, the PBAT and starch blend film produced by this invention combines mechanical properties (tensile strength increased by more than 40%), antibacterial properties (weight loss of fruits and vegetables within 7 days ≤16%), and rapid degradation (natural degradation rate >60% within 30 days), making it widely applicable in areas such as food wrap and degradable mulch. Compared with traditional PBAT and starch blend films, its process is simplified, cost is reduced by 30%, and it fully complies with food safety standards, providing an efficient and environmentally friendly solution for replacing plastics.

[0022] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention.

[0024] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0025] The present invention proposes a method for preparing a multifunctional biodegradable PBAT and starch blend film using potato peels and PBAT (biodegradable polybutylene terephthalate-adipate) as raw materials, which includes: an efficient starch extraction process: by optimizing the solid-liquid separation and drying steps, high-purity starch (low gelatinization temperature and high viscosity) is extracted from potato peels to provide an excellent matrix for the membrane material; a β-cyclodextrin inclusion technology: using a saturated aqueous solution method to encapsulate thyme essential oil in β-cyclodextrin (β-cyclodex trin) cavity to form sustained-release microcapsules, solving the problem of essential oil volatility and giving the PBAT and starch blend film long-lasting antibacterial properties; synergistic enhancement system: the introduction of glycerol plasticizer and sodium carboxymethyl cellulose (CMC) significantly improves the film's toughness (tensile strength reaches 26.6-28.2MPa) and high-temperature resistance (can withstand microwave heating) through hydrogen bond reorganization and plasticizing effect; green process: no toxic reagents are required throughout the process, and the utilization rate of potato peel waste reaches more than 95%, achieving high-value utilization of resources.

[0026] Example 1

[0027] The multifunctional biodegradable PBAT and starch blend film is prepared in the following steps:

[0028] 200 g of washed potato peel pieces and 400 g of deionized water were stirred at 200 rpm for 1 h at 20-30 ° C, and passed through an 80 μm sieve to separate the solid and liquid. The filtrate was placed in a refrigerator for decantation, suction filtered, and dried to obtain potato starch; 1 g of thyme essential oil and 10 g of anhydrous ethanol were mixed to form a stable essential oil solution, and then 5 parts of the essential oil solution were mixed with 45 g of β-cyclodextrin at 45 ° C, stirred for 30 min, placed in a refrigerator for 24 h for inclusion, then suction filtered, and placed in an oven at 60 ° C for drying for 3 h to obtain essential oil microcapsule powder; 10 g potato starch, 5 g sodium carboxymethyl cellulose and 320 g deionized water were mixed into a starch aqueous solution and gelatinized at 80-90 ° C; 5 parts of glycerol were added dropwise at 70-80 ° C, followed by adding 3 g of thyme essential oil microcapsules to form a mixed solution A, 24 g of PBAT was added to the mixed solution A to form a mixture B, and the mixture B was placed at 140-150 ° C and a speed of 300-500 r / min. Stir until it becomes viscous, cast onto a plastic plate, and dried at room temperature for 48 hours to obtain a multifunctional PBAT and starch blend film.

[0029] The sodium carboxymethyl cellulose is a binder that improves the toughness of the membrane through hydrogen bond reorganization;

[0030] The glycerol is a plasticizer that reduces the rigidity of the starch molecular chain and enhances ductility;

[0031] β-cyclodextrin inclusion technology achieves sustained release of essential oils, avoiding volatilization losses caused by direct addition.

[0032] Example 2

[0033] The multifunctional PBAT and starch blend film is produced in the following steps:

[0034] Potato starch and essential oil microcapsule powders are prepared in advance according to the present invention. 100g of potato starch, 30g of sodium carboxymethyl cellulose, and 3000g of deionized water are mixed and gelatinized at 80-90°C. After gelatinization, 40g of glycerin and 20g of Cinnamomum camphora essential oil microcapsule powder are added to form a mixed solution A. 24g of PBAT is added to the mixed solution A to form a mixture B. Mixture B is stirred at 140-150°C and a rotation speed of 300-500 rpm until it becomes viscous. The mixture is then cast onto a plastic plate and dried at room temperature for 48 hours to produce a multifunctional PBAT and starch blend film.

[0035] Example 3

[0036] Based on Example 1, in the gelatinization step, 10g of potato starch, 5g of sodium carboxymethyl cellulose, and 320g of deionized water were mixed to form a starch aqueous solution, gelatinized at 80-90°C, and blended with PBAT at 140-150°C. In addition, 0.03g of Au:Ag NPs were added. Other steps were the same as in Example 1. The preparation method of the Au:Ag NPs (Au:Ag nanoparticles) was as follows:

[0037] Chrysanthemum indicum leaves were collected, washed with ultrapure water, dried at 60°C, and ground to obtain Chrysanthemum indicum leaf powder. 100g of Chrysanthemum indicum powder was added to a steam distillation apparatus with 500mL of distilled water. The system was heated to 100°C and steam distilled for 5h. After the distillation, the oil and water were separated to obtain Chrysanthemum indicum essential oil.

[0038] Au:Ag NPs were prepared using essential oils as reducing agents and stabilizers.

[0039] Take 28 μL of essential oil and add it to 70 mL of acetone to prepare a solution. Take 2 mL of essential oil solution and add 13 mL of ethanol and 10 mL of water to further dilute to obtain diluted essential oil. The specific steps are as follows: Take 8.65 mL of AgNO3 (2.9×10 -4 M) solution and 31.35 mL HAuCl4 (2.49 × 10 -4 M) The solution was vigorously stirred at 373 K and pH = 7, and the diluted essential oil was added dropwise. The color of the solution gradually changed. The reaction lasted for half an hour to synthesize Au:Ag NPs.

[0040] Comparative Example 1

[0041] The PBAT and starch blend film of Comparative Example 1 is prepared as follows:

[0042] The potato starch and glycerol were directly mixed and placed in a mixer with low-speed stirring (200 rpm) at 60°C for 10 minutes. The plasticized starch, PBAT, coupling agent, lubricant, and antioxidant were added to a twin-screw extruder. The processing temperature was set to 110-180°C, the screw speed was 200 rpm, and the vacuum degree was 0.03 MPa. After extrusion, the traditional PBAT and starch blended masterbatch was obtained by water-cooling and pelletizing. The masterbatch was put into a casting machine, and the casting temperature was set to 150-155°C and the casting speed was 50 r / min. After cooling and shaping on a cooling roller at 25°C, the film was wound to obtain a PBAT and starch blended film with a thickness of about 50 μm.

[0043] Performance testing:

[0044] (1) Tensile property test: 4×75 mm dumbbell-shaped film specimens were used for tensile mechanical property test. The tensile speed was 10 mm / min, the gauge length was 20 mm, and the environmental test was carried out at a relative humidity of 50% and a temperature of 25°C.

[0045] (2) Degradability test:

[0046] The degradation performance test method of GB / T 20197-2006 was used to test the degradation performance of the material.

[0047] The tensile properties and degradation performance test results of Examples 1-3 and Comparative Example 1 are shown in Table 1 below.

[0048] Table 1 Test results of tensile properties and degradation properties

[0049]

[0050] Freshness experiment:

[0051] Mangoes were sealed with the PBAT and starch blend films prepared in Examples 1-3 and Comparative Example 1 and stored for 7 days at 20°C / 70% relative humidity for comparison. The PBAT and starch blend films prepared in Example 1 showed a small amount of black spots on the mangoes after 7 days of storage, with a weight loss of 12%, and a largely unchanged taste. The PBAT and starch blend films prepared in Example 2 also showed a small amount of black spots on the mangoes after 7 days of storage, with a weight loss of 16%, and a largely unchanged taste. The PBAT and starch blend films prepared in Example 2 showed fewer black spots on the mangoes after 7 days of storage than those in Examples 1-2, with a weight loss of 9%, and a largely unchanged taste. The PBAT and starch blend films prepared in Comparative Example 1 showed a large amount of black spots on the mangoes after 7 days of storage, making them virtually inedible, with a weight loss of 48%.

[0052] The present invention achieves the following advantages by integrating potato peel resource utilization, blending with PBAT, microcapsule sustained release and synergistic enhancement technology: improved mechanical properties: tensile strength reaches 26.6-28.2MPa (more than 40% higher than that of ordinary PBAT and starch blended films), and can withstand microwave heating (no deformation at 120°C); long-term antibacterial properties: thyme essential oil sustained-release microcapsules give the film broad-spectrum antibacterial ability, and the weight loss rate of fruits and vegetables within 7 days is ≤16% (control group>48%); efficient degradability: weight loss rate under natural environment within 30 days is>60%, and it is completely degraded into harmless glucose; green and safe: no toxic reagents are used throughout the process, and it complies with the GB 4806.7-2016 food safety standard; cost advantage: by utilizing discarded potato peels, raw material costs are reduced by 35% and process energy consumption is reduced by 20%. The obtained PBAT and starch blend film is suitable for: food preservative film: extending the shelf life of fruits and vegetables, replacing traditional PE film; degradable ground film: improving soil structure after natural degradation; medical packaging material: combining antibacterial properties and biocompatibility.

[0053] Throughout this specification, terms such as "one embodiment" or "some embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0054] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a blended film of degraded PBAT and starch, characterized in that: The following steps are involved: a. Starch extraction: potato peels were mixed with deionized water in a mass ratio of 1: (1.5-3), stirred at 20-30 ° C and 180-220 rpm for 0.5-1.5 hours, and the solid and liquid were separated through a 50-100 μm sieve. The filtrate was dried to obtain potato starch; b. Microcapsule Preparation: The essential oil and anhydrous ethanol were mixed in a mass ratio of 1: (4-12) to form a stable essential oil solution, the solution was stirred with β-cyclodextrin in a mass ratio of 1: (8-15) at 40-50 ° C for 20-40 minutes, refrigerated for 12-36 hours to complete the inclusion, filtered, and dried to obtain essential oil microcapsule powder; c. Gelatinization: Mix potato starch, sodium carboxymethyl cellulose and deionized water in a mass ratio of 1:(0.4-0.6):(30-45) and gelatinize at 75-95°C to form a starch aqueous solution; d. Film formation: Glycerol and essential oil microcapsule powder are added to the starch aqueous solution, with the mass ratio of glycerol to potato starch being 0.4-0.6:1, and the mass ratio of essential oil microcapsule powder to potato starch being 0.1-0.5:1, to form mixture A. PBAT is added to mixture A, with the mass ratio of PBAT to potato starch being 12:5, to form mixture B. Mixture B is placed at 140-150°C and a rotation speed of 300-500 r / min, stirred, and then cast into a film. The film is dried at room temperature for 24-72 hours and then peeled off.

2. The method according to claim 1, wherein In step d, glycerol is added dropwise to the gelatinized liquid at 70-80° C., followed by the addition of essential oil microcapsule powder, and finally blended with PBAT.

3. The method according to claim 2, wherein The glycerol in step d is added dropwise in 2-4 times, with an addition interval of 3-10 minutes.

4. The method according to any one of claims 1 to 3, characterized in that The plant essential oil in step b is thyme essential oil, eugenol or camphor leaf essential oil.

5. The method according to claim 4, wherein In step a, potato peels and deionized water are mixed in a mass ratio of 1:2, stirred at room temperature and 200 rpm for 1 hour, and the solid and liquid are separated through an 80 μm sieve. The filtrate is decanted, filtered, and dried to obtain potato starch.

6. The method according to claim 5, wherein In step b, the plant essential oil and anhydrous ethanol are mixed in a mass ratio of 1:(5-10) to form a stable essential oil solution, the solution is stirred with beta-cyclodextrin in a mass ratio of 1:(5-12) at 45° C. for 30 minutes, refrigerated for 24 hours to complete inclusion, and then filtered and dried at 60° C. for 3 hours to obtain essential oil microcapsule powder.

7. The method according to claim 6, wherein In step c, potato starch, sodium carboxymethyl cellulose and deionized water are mixed in a mass ratio of 1:0.5:(32-40), and gelatinized at 80-90° C. to form a starch aqueous solution.

8. The method according to claim 7, wherein In step d, glycerol and essential oil microcapsule powder are added to the gelatinized liquid, the mass ratio of glycerol to potato starch is 0.5:1, and the mass ratio of essential oil microcapsule powder to potato starch is (0.2-0.4):1 to form a mixed solution A, PBAT is added to the mixed solution A, and the mass ratio of PBAT to potato starch is 12:5 to form a mixture B. The mixture B is placed at 140-150°C and a speed of 300-500r / min and stirred until it becomes viscous, cast onto a plastic plate, and dried at room temperature for 48 hours before peeling off the film.

9. The method according to claim 8, wherein The method further comprises adding Au:Ag NPs in step c, wherein the Au:Ag NPs are mixed with deionized water at a mass ratio of 0.001-0.5:

100.

10. A PBAT and starch blend film prepared by the method according to any one of claims 1 to 8, characterized in that: Tensile strength ≥25MPa, weight loss rate >60% in natural environment after 30 days.

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