Star-shaped polylactic acid, biodegradable polyester composite material based on PBAT / s-PLA and wrapping film
Biodegradable stretch film was prepared by blending star-shaped polylactic acid (PLA) with PBAT, which solved the pollution problem of non-degradable stretch film, improved the mechanical properties and biodegradability of stretch film, and achieved a high-strength and high-toughness biodegradable effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-11
- Publication Date
- 2026-04-07
AI Technical Summary
Existing non-degradable stretch films cause environmental pollution problems. PBAT has low tensile strength and insufficient elongation at break, while PLA film has improved elongation at break but reduced tensile strength.
Biodegradable polyester composite materials were prepared by blending star-shaped polylactic acid (s-PLA) with PBAT, combined with nano-calcium carbonate, compatibilizer, lubricant, tackifier and antioxidant, using a small high-speed mixer and twin-screw extruder, and then blown into a winding film.
It significantly improves the elongation at break, tensile strength, peel strength and overlap strength of the stretch film, while meeting the requirements for biodegradation, with the products being carbon dioxide and water, which comply with relevant standards.
Smart Images
Figure CN121801060A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biodegradable packaging materials, and discloses a star-shaped polylactic acid and its biodegradable polyester composite material based on PBAT / s-PLA and a stretch film. Background Technology
[0002] Stretch film is a self-adhesive wrapping material that uses its surface elasticity and tensile strength to wrap goods. Polyethylene (PE) stretch film has high tensile strength, tear strength, good self-adhesion, and transparency, and is widely used in bundling and packaging in industries such as electronics, building materials, chemicals, metal products, auto parts, wires and cables, daily necessities, food, and papermaking. However, waste stretch film made of PE is difficult to decompose in the environment, causing serious white pollution to land, oceans, and water sources. Therefore, the development of biodegradable stretch film is of great significance for solving the increasingly serious problem of white pollution.
[0003] Polybutylene adipate terephthalate (PBAT) is a fully biodegradable aliphatic-aromatic copolyester. Its degradation primarily occurs through enzymatic decomposition by bacteria, fungi, or algae in the environment, and non-enzymatic degradation via thermal degradation and chemical hydrolysis, ultimately producing carbon dioxide and water. PBAT exhibits excellent ductility and elongation at break, but its relatively low tensile strength limits its application in fields such as stretch wrapping films. Polylactic acid (PLA) possesses excellent tensile strength, which can improve the tensile strength of PBAT films, but its reduced elongation at break limits its applications. Star-shaped polylactic acid (s-PLA) has a unique core-arm structure, exhibiting high strength and high toughness, significantly improving the elongation at break of films. Furthermore, the increased number of hydroxyl groups in this star-shaped structure forms multiple intermolecular hydrogen bonds, enhancing intermolecular forces and increasing the tensile strength of the film. The hydroxyl groups in s-PLA molecules can form hydrogen bond networks with auxiliary molecules such as PEG-400, stearic acid, glycerol, and sorbitol, enhancing cohesion and improving the peel strength of the film. Furthermore, s-PLA is smaller in size than linear polylactic acid (PLA) of the same molecular weight, exhibiting better flowability and easier processing. Like PLA, s-PLA also possesses good biodegradability, with degradation products being carbon dioxide and water. Blending PBAT with s-PLA not only improves the processability of PBAT but also significantly enhances the mechanical properties of the film. Summary of the Invention
[0004] To address the environmental pollution problem caused by non-degradable waste stretch film, this invention aims to provide a star-shaped polylactic acid (s-PLA), along with a biodegradable polyester composite material based on PBAT / s-PLA and a stretch film. The invention first prepares star-shaped polylactic acid (s-PLA), a simple synthesis process that produces a biodegradable product. Its unique core-arm structure exhibits high strength and toughness, significantly improving the film's elongation at break. Furthermore, the increased number of hydroxyl groups in the star-shaped structure forms multiple intermolecular hydrogen bonds, enhancing intermolecular forces and improving the film's tensile strength. Then, PBAT, s-PLA, fillers, compatibilizers, lubricants, and antioxidants are placed in a small high-speed mixer and stirred at high speed for a controlled temperature for a specific time. A tackifier is then added, and stirring continues for a further time to obtain a modified mixture. This modified mixture is then melt-blended in a small twin-screw extruder, extruded, and pelletized to obtain a PBAT / s-PLA biodegradable polyester composite material with excellent processing properties. Finally, this composite material is blown into a film using a small blown film machine to obtain a biodegradable stretch film with good mechanical properties.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a star-shaped polylactic acid and its biodegradable polyester composite material based on PBAT / s-PLA and a stretch film, wherein the biodegradable polyester composite material and its stretch film are based on polybutylene adipate terephthalate (PBAT) as the main base material, star-shaped polylactic acid (s-PLA) as the auxiliary material, nano-calcium carbonate as the filler, and compatibilizers, lubricants, tackifiers and antioxidants as additives.
[0006] A star-shaped polylactic acid, its PBAT / s-PLA-based biodegradable polyester composite material, and a stretch film, comprising the following steps:
[0007] (1) Preparation of star-shaped polylactic acid (s-PLA):
[0008] Weigh lactide, pentaerythritol, and stannous octoate into a reaction flask, purge with nitrogen, and stir at a certain temperature for a certain time. After the reaction is complete, cool to room temperature, dissolve the crude product in dichloromethane, filter, add the filtrate to methanol, and let stand for a certain time to obtain a precipitate. Filter the precipitate, and the resulting white solid, after drying, is the product star-shaped polylactic acid (s-PLA).
[0009] The mass ratio of lactide, pentaerythritol, and stannous octoate is 300-500:2-6:1-3. Preferably, the mass ratio of lactide, pentaerythritol, and stannous octoate is 400:4:1.
[0010] The reaction temperature is 120~150℃. Preferably, the reaction temperature is 140℃.
[0011] The reaction time is 24-50 h. Preferably, the reaction time is 48 h.
[0012] The volume ratio of dichloromethane to methanol is 3:4 to 6. Preferably, the volume ratio of dichloromethane to methanol is 3:5.
[0013] The settling temperature is 1~3℃. Preferably, the settling temperature is 2℃.
[0014] The settling time is 2 to 5 hours. Preferably, the settling time is 4 hours.
[0015] (2) Preparation of modified mixture:
[0016] The PBAT / s-PLA-based biodegradable polyester composite material includes polybutylene adipate terephthalate, star-shaped polylactic acid, filler, compatibilizer, lubricant, tackifier, and antioxidant.
[0017] The filler is one of nano-calcium carbonate (n-CaCO3), talc, and nano-silica (n-SiO2); the compatibilizer is one of PEG-400, PEG-4000, PEG-5000, and PEG-6000; the lubricant is one of stearic acid, liquid paraffin, solid paraffin, calcium stearate, and oleamide; the tackifier is two of glycerol, sorbitol, rosin, rosin glyceryl ester, and pentaerythritol rosin ester; and the antioxidant is one of antioxidant B215, antioxidant 168, and antioxidant B225.
[0018] Preferably, the filler is nano-calcium carbonate (n-CaCO3); the compatibilizer is PEG-400; the lubricant is stearic acid; the tackifier is glycerin or sorbitol; and the antioxidant is antioxidant B215.
[0019] Weigh out PBAT, s-PLA, filler, compatibilizer, lubricant and antioxidant and add them to a small high-speed mixer. Control the material temperature and stir for a certain time. Then add thickener and continue stirring for a certain time before discharging to obtain modified mixture.
[0020] Preferably, the mass ratio of PBAT, s-PLA, n-CaCO3, PEG-400, stearic acid, glycerin, sorbitol and B215 is 395~445:25~75:15:5:6:1:2:1.
[0021] The material temperature in the high-speed mixer is 85~95℃. Preferably, the temperature in the mixer is 90℃.
[0022] The stirring speed is 5~20 Hz. Preferably, the stirring speed is 15 Hz.
[0023] Continue stirring for 5-15 minutes. Preferably, the stirring time is 25 minutes, followed by a 10-minute stirring period.
[0024] (3) Preparation of biodegradable polyester composite material: The modified mixture is placed in a small twin-screw extruder, the temperature of each zone is controlled for melt blending, and the mixture is extruded and pelletized to obtain biodegradable polyester composite material.
[0025] The temperatures of each zone of the small twin-screw extruder are as follows: Zone 1 140~145℃, Zone 2 145~150℃, Zone 3 145~150℃, Zone 4 150~155℃, Zone 5 150~155℃.
[0026] Preferably, the temperatures of each zone of the small twin-screw extruder are: zone 1 140℃, zone 2 145℃, zone 3 145℃, zone 4 150℃, and zone 5 150℃.
[0027] (4) Making biodegradable stretch film: Place the biodegradable polyester composite material in a small blown film machine, control the temperature of each zone, and blow the film to obtain biodegradable stretch film.
[0028] The temperatures of each zone of the small blown film machine are as follows: Zone 1 140~145℃, Zone 2 145~150℃, Zone 3 145~150℃, Zone 4 150~155℃, Zone 5 150~155℃, and the thickness of the stretch film is 0.02~0.025 mm.
[0029] Preferably, the temperatures of each zone of the small blown film machine are: zone 1 140℃, zone 2 145℃, zone 3 145℃, zone 4 150℃, and zone 5 150℃, and the thickness of the wrapping film is 0.02 mm.
[0030] The beneficial effects of this invention are:
[0031] Compared with the prior art, the advantages of the present invention are as follows: (1) The present invention is the first to use star-shaped polylactic acid (s-PLA) as an auxiliary material to blend with PBAT resin. Due to the unique core-arm structure of s-PLA, it has the advantages of high strength and high toughness, which can significantly improve the elongation at break of the film. At the same time, more hydroxyl groups in the star-shaped structure form multiple intermolecular hydrogen bonds, and the intermolecular forces are enhanced, which increases the tensile strength and tear strength of the film. (2) s-PLA, PEG-400, stearic acid, glycerol and sorbitol can form a hydrogen bond network, which enhances the cohesive effect and can significantly improve the peel strength and overlap strength of the film. (3) s-PLA is smaller in size than PLA of the same molecular weight, has a small hydrodynamic volume, good fluidity, mild reaction conditions, and is easy to process. (4) The polyester composite material is biodegraded under the conditions of composting (test period of 126 days), with a biodegradation rate of 92.21% and a relative biodegradation rate of 94.36%. The products are carbon dioxide and water, which meet the requirements of GB / T 20197-2006 standard. Attached Figure Description
[0032] Figure 1 It is s-PLA 1 H NMR spectrum.
[0033] Figure 2 These are photographs of the biodegradable polyester composite material 1 (A) and the stretch film 1 (B).
[0034] Figure 3 These are photographs of the biodegradable polyester composite material 2(A) and the stretch film 2(B).
[0035] Figure 4 These are photographs of the biodegradable polyester composite material 3(A) and the stretch film 3(B).
[0036] Figure 5 These are actual photos of the biodegradable polyester composite material 4(A) and the stretch film 4(B).
[0037] Figure 6 This is a graph showing the change in carbon dioxide production of biodegradable polyester composite material 1 over time.
[0038] Figure 7 This is a graph showing the change in the biodegradability rate of biodegradable polyester composite material 1 over time. Detailed Implementation
[0039] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.
[0040] Example 1: A star-shaped polylactic acid and its PBAT / s-PLA-based biodegradable polyester composite material 1 and a stretch film 1
[0041] 1. Preparation of star-shaped polylactic acid (s-PLA)
[0042] 0.8 kg of lactide, 0.008 kg of pentaerythritol, and 0.002 kg of stannous octoate were weighed and placed in a reaction flask. Nitrogen gas was introduced, and the mixture was stirred at 140 °C for 48 h. After the reaction was completed, the mixture was cooled to room temperature, and the crude product was dissolved in 1.5 L of dichloromethane and filtered. The filtrate was added to 2.5 L of methanol, and the mixture was allowed to stand at 2 °C for 4 h to obtain a precipitate. The precipitate was filtered, dried, and the resulting white solid was the product, star-shaped polylactic acid (s-PLA). The synthetic route is shown in Scheme 1. Figure 1 It is s-PLA 1 The 1H NMR spectrum shows that the chemical shifts of the methyl (-CH3) and methine (-CH) protons on the s-PLA segment are at δ1.55 and δ5.16 ppm, respectively; the chemical shift of the methylene (-CH2) proton on the pentaerythritol segment is at δ4.17 ppm; and the chemical shift of the methine (-CH) proton on the terminal PLA segment is at δ4.37 ppm. No chemical shift of the terminal hydroxyl (-OH) proton on the pentaerythritol segment is observed, indicating that a four-armed s-PLA was obtained.
[0043]
[0044] Synthetic route of Scheme 1 s-PLA
[0045] 2. Preparation of modified mixture
[0046] Weigh 4.45 kg PBAT, 0.25 kg s-PLA, 0.15 kg n-CaCO3, 0.05 kg PEG-400, 0.06 kg stearic acid and 0.01 kg B215 and place them in a small high-speed mixer. Control the material temperature at 90℃, the stirring speed at 15 Hz and stir for 25 min. Then add 0.01 kg glycerol and 0.02 kg sorbitol and continue stirring for 10 min to obtain the modified mixture.
[0047] 3. Preparation of biodegradable polyester composite material 1
[0048] The modified mixture was placed in a small twin-screw extruder, and the temperatures in zones 1-5 were controlled at 140°C, 145°C, 145°C, 150°C, and 150°C respectively. The mixture was then melt-blended, extruded, and pelletized to obtain biodegradable polyester composite material 1. A photograph of biodegradable polyester composite material 1 is shown below. Figure 2 As shown in (A).
[0049] 4. Fabrication of biodegradable stretch film 1
[0050] Biodegradable polyester composite material 1 was placed in a blown film machine, and the temperatures were controlled at 140℃ in zone 1, 145℃ in zone 2, 145℃ in zone 3, 150℃ in zone 4, and 150℃ in zone 5 to obtain biodegradable stretch film 1. A photograph of stretch film 1 is shown below. Figure 2 As shown in (B). Film thickness: 0.02 mm, light transmittance: 89%, haze: 7.5%, elongation at break: 675% longitudinally and 654% transversely, tensile strength: 38 MPa longitudinally and 34 MPa transversely, tear strength: 65 kN / m longitudinally and 59 kN / m transversely, peel strength: 1.15 N / m, lap strength: 218 N / m.
[0051] Example 2: A star-shaped polylactic acid and its PBAT / s-PLA-based biodegradable polyester composite material 2 and a stretch film 2
[0052] 1. Preparation of star-shaped polylactic acid (s-PLA)
[0053] 0.8 kg of lactide, 0.008 kg of pentaerythritol, and 0.002 kg of stannous octoate were weighed and placed in a reaction flask. Nitrogen gas was introduced, and the mixture was stirred at 140 °C for 48 h. After the reaction was completed, the mixture was cooled to room temperature, and the crude product was dissolved in 1.5 L of dichloromethane and filtered. The filtrate was added to 2.5 L of methanol, and the mixture was allowed to stand at 2 °C for 4 h to obtain a precipitate. The precipitate was filtered, dried, and the resulting white solid was the product, star-shaped polylactic acid (s-PLA). The synthetic route is shown in Scheme 1. Figure 1 It is s-PLA 1 The 1H NMR spectrum shows that the chemical shifts of the methyl (-CH3) and methine (-CH) protons on the s-PLA segment are at δ1.55 and δ5.16 ppm, respectively; the chemical shift of the methylene (-CH2) proton on the pentaerythritol segment is at δ4.17 ppm; and the chemical shift of the methine (-CH) proton on the terminal PLA segment is at δ4.37 ppm. No chemical shift of the terminal hydroxyl (-OH) proton on the pentaerythritol segment is observed, indicating that a four-armed s-PLA was obtained.
[0054] 2. Preparation of modified mixture
[0055] Weigh 4.20 kg PBAT, 0.5 kg s-PLA, 0.15 kg n-CaCO3, 0.05 kg PEG-400, 0.06 kg stearic acid and 0.01 kg B215 and place them in a small high-speed mixer. Control the material temperature at 90℃, the stirring speed at 15 Hz and stir for 25 min. Then add 0.01 kg glycerol and 0.02 kg sorbitol and continue stirring for 10 min to obtain the modified mixture.
[0056] 3. Preparation of biodegradable polyester composite material 2
[0057] The modified mixture was placed in a small twin-screw extruder, and the temperatures in zones 1-5 were controlled at 140°C, 145°C, 145°C, 150°C, and 150°C respectively. The mixture was then melt-blended, extruded, and pelletized to obtain biodegradable polyester composite material 2. A photograph of biodegradable polyester composite material 2 is shown below. Figure 3 As shown in (A).
[0058] 4. Fabrication of biodegradable stretch film 2
[0059] Biodegradable polyester composite material 2 was placed in a blown film machine, and the temperatures were controlled at 140℃ in zone 1, 145℃ in zone 2, 145℃ in zone 3, 150℃ in zone 4, and 150℃ in zone 5 to obtain biodegradable stretch film 2. A photograph of stretch film 2 is shown below. Figure 3 As shown in (B). Film thickness: 0.02 mm, light transmittance: 90%, haze: 6.8%, elongation at break: 685% longitudinally and 661% transversely, tensile strength: 41 MPa longitudinally and 38 MPa transversely, tear strength: 68 kN / m longitudinally and 63 kN / m transversely, peel strength: 1.26 N / m, lap strength: 235 N / m.
[0060] Example 3: A star-shaped polylactic acid and its PBAT / s-PLA-based biodegradable polyester composite material 3 and a stretch film 3
[0061] 1. Preparation of star-shaped polylactic acid (s-PLA)
[0062] 0.8 kg of lactide, 0.008 kg of pentaerythritol, and 0.002 kg of stannous octoate were weighed and placed in a reaction flask. Nitrogen gas was introduced, and the mixture was stirred at 140 °C for 48 h. After the reaction was completed, the mixture was cooled to room temperature, and the crude product was dissolved in 1.5 L of dichloromethane and filtered. The filtrate was added to 2.5 L of methanol, and the mixture was allowed to stand at 2 °C for 4 h to obtain a precipitate. The precipitate was filtered, dried, and the resulting white solid was the product, star-shaped polylactic acid (s-PLA). The synthetic route is shown in Scheme 1. Figure 1 It is s-PLA 1 The 1H NMR spectrum shows that the chemical shifts of the methyl (-CH3) and methine (-CH) protons on the s-PLA segment are at δ1.55 and δ5.16 ppm, respectively; the chemical shift of the methylene (-CH2) proton on the pentaerythritol segment is at δ4.17 ppm; and the chemical shift of the methine (-CH) proton on the terminal PLA segment is at δ4.37 ppm. No chemical shift of the terminal hydroxyl (-OH) proton on the pentaerythritol segment is observed, indicating that a four-armed s-PLA was obtained.
[0063] 2. Preparation of modified mixture
[0064] Weigh 3.95 kg PBAT, 0.75 kg s-PLA, 0.15 kg n-CaCO3, 0.05 kg PEG-400, 0.06 kg stearic acid and 0.01 kg B215 and place them in a small high-speed mixer. Control the material temperature at 90℃, the stirring speed at 15 Hz and stir for 25 min. Then add 0.01 kg glycerol and 0.02 kg sorbitol and continue stirring for 10 min to obtain the modified mixture.
[0065] 3. Preparation of biodegradable polyester composite materials
[0066] The modified mixture was placed in a small twin-screw extruder, and the temperatures in zones 1-5 were controlled at 140°C, 145°C, 145°C, 150°C, and 150°C respectively. The mixture was then melt-blended, extruded, and pelletized to obtain biodegradable polyester composite material 3. A photograph of biodegradable polyester composite material 3 is shown below. Figure 4 As shown in (A).
[0067] 4. Fabrication of biodegradable stretch film 3
[0068] Biodegradable polyester composite material 3 was placed in a blown film machine, and the temperatures were controlled at 140℃ in zone 1, 145℃ in zone 2, 145℃ in zone 3, 150℃ in zone 4, and 150℃ in zone 5 to obtain biodegradable stretch film 3. A photograph of stretch film 3 is shown below. Figure 4 As shown in (B). Film thickness: 0.02 mm, light transmittance: 91%, haze: 6.0%, elongation at break: 695% longitudinally and 673% transversely, tensile strength: 49 MPa longitudinally and 44 MPa transversely, tear strength: 73 kN / m longitudinally and 66 kN / m transversely, peel strength: 1.38 N / m, lap strength: 256 N / m.
[0069] As can be seen from the three examples above, with the increase of s-PLA content, the elongation at break, tensile strength, peel strength, lap strength, and tear strength all increase. This is because the unique core-arm structure of s-PLA enhances its toughness, leading to an increase in the film's elongation at break. Although the crystallinity of PLA molecules in s-PLA is somewhat reduced, resulting in a decrease in the film's tensile and tear strength, the increased intermolecular forces due to the formation of multiple intermolecular hydrogen bonds by more hydroxyl groups in the star-shaped structure further increase these strengths. The hydrogen bond network formed between s-PLA molecules and PEG-400, stearic acid, glycerol, and sorbitol enhances cohesion, thus increasing the film's peel strength and lap strength.
[0070] Comparative Example 1: A PBAT / PLA-based biodegradable polyester composite material 4 and a stretch film 4
[0071] 1. Preparation of modified mixture
[0072] Weigh 4.45 kg PBAT, 0.25 kg PLA, 0.15 kg n-CaCO3, 0.05 kg PEG-400, 0.06 kg stearic acid and 0.01 kg B215 and place them in a small high-speed mixer. Control the material temperature at 90℃, the stirring speed at 15 Hz and stir for 25 min. Then add 0.01 kg glycerol and 0.02 kg sorbitol and continue stirring for 10 min to obtain the modified mixture.
[0073] 2. Preparation of biodegradable polyester composite materials 4
[0074] The modified mixture was placed in a small twin-screw extruder, and the temperatures in zones 1-5 were controlled at 140°C, 145°C, 145°C, 150°C, and 150°C respectively. The mixture was then melt-blended, extruded, and pelletized to obtain biodegradable polyester composite material 4. A photograph of biodegradable polyester composite material 4 is shown below. Figure 5 As shown in (A).
[0075] 3. Fabrication of biodegradable stretch film 4
[0076] Biodegradable polyester composite material 4 was placed in a small blown film machine, and the temperatures in zones 1-5 were controlled at 140℃, 145℃, 145℃, 150℃, and 150℃ respectively to obtain biodegradable stretch film 4. A photograph of stretch film 4 is shown below. Figure 5 As shown in (B). Film thickness: 0.02 mm, light transmittance: 84%, haze: 9.2%, elongation at break: 560% longitudinally and 545% transversely, tensile strength: 37 MPa longitudinally and 32 MPa transversely, tear strength: 64 kN / m longitudinally and 56 kN / m transversely, peel strength: 0.75 N / m, lap strength: 175 N / m.
[0077] Compared to Example 1, Comparative Example 1 used the same mass of PLA instead of s-PLA, resulting in decreased light transmittance, elongation at break, peel strength, and lap strength of the film, while increasing haze. This is because crystalline PLA molecules have higher tensile strength, leading to a lower elongation at break. Linear PLA molecules do not readily form hydrogen bond networks with PEG-400, stearic acid, glycerol, and sorbitol, weakening cohesion and reducing peel strength and lap strength. PLA is a crystalline polymer; higher crystallinity results in decreased light transmittance and increased haze in the film.
[0078] The biodegradability of biodegradable polyester composite material 1 was tested by the Jilin Provincial Institute of Product Quality Supervision and Inspection, using the standard GB / T 19277.1-2011 "Determination of the final aerobic biodegradation capacity of materials under controlled composting conditions—Method for determining the release of carbon dioxide—Part 1: General Method". The reference material in the experimental data was provided by the Jilin Provincial Institute of Product Quality Supervision and Inspection, and the results are as follows: Figure 6 , Figure 7 As shown in Table 1, it can be biodegraded under mature composting conditions (experimental period of 126 days), with a biodegradation rate of 92.21% and a relative biodegradation rate of 94.36%. The products are carbon dioxide and water, which meet the requirements of GB / T 20197-2006 standard.
[0079] Table 1. Biodegradability data of biodegradable polyester composite material 1 and reference material.
[0080] Related information Biodegradable polyester composite material 1 Reference material (cellulose) Inoculation Well-rotted compost Well-rotted compost <![CDATA[Total volatile solid ratio mat v / d > 68.85% 99.99% 45-day biodegradation rate 61.61% 76.13% Final biodegradation rate 92.21% 97.72% test cycle 126 days 126 days
[0081] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect, and all such modifications or substitutions are within the protection scope of the present invention as long as they meet the usage requirements.
Claims
1. Star-shaped polylactic acid s-PLA, characterized in that, The preparation method includes the following steps: 1) Weigh lactide, pentaerythritol and stannous octoate into a reaction flask, purge with nitrogen, and stir at a certain temperature for a certain time. 2) After the reaction is complete, cool to room temperature, dissolve the crude product in dichloromethane, filter, add the filtrate to methanol, and after standing for a certain time at a certain temperature, a precipitate is obtained. Filter the precipitate, and the white solid obtained is dried to obtain the product star-shaped polylactic acid s-PLA.
2. The star-shaped polylactic acid according to claim 1, characterized in that, In step 1), the mass ratio of lactide, pentaerythritol, and stannous octoate is 300-500:2-6:1-3, the reaction temperature is 120-150℃, and the reaction time is 24-50 h; in step 2), the volume ratio of dichloromethane and methanol is 3:4-6, the standing temperature is 1-3℃, and the standing time is 2-5 h.
3. A biodegradable polyester composite material based on PBAT / s-PLA, characterized in that, The biodegradable polyester composite material based on PBAT / s-PLA comprises, by weight parts, 350-450 parts of polybutylene adipate-terephthalate, 10-100 parts of star-shaped polylactic acid as described in claim 1, 5-25 parts of filler, 4-6 parts of compatibilizer, 4-8 parts of lubricant, 1-9 parts of tackifier, and 1-2 parts of antioxidant.
4. The method for preparing a biodegradable polyester composite material based on PBAT / s-PLA according to claim 3, characterized in that, Includes the following steps: 1) Weigh out polybutylene adipate-terephthalate, the star-shaped polylactic acid as described in claim 1, filler, compatibilizer, lubricant and antioxidant and place them in a small high-speed mixer. Control the temperature and stir at high speed for a certain time. Then add the thickener and continue stirring for a certain time before discharging to obtain the modified mixture. 2) The modified mixture is placed in a small twin-screw extruder, and the temperature of each zone is controlled for melt blending. After extrusion and pelletizing, a biodegradable polyester composite material is obtained.
5. The method for preparing a star-shaped polylactic acid and its biodegradable polyester composite material based on PBAT / s-PLA according to claim 4, characterized in that, The filler is one of nano-calcium carbonate (n-CaCO3), talc, and nano-silica (n-SiO2); the compatibilizer is one of PEG-400, PEG-4000, PEG-5000, and PEG-6000; the lubricant is one of stearic acid, liquid paraffin, solid paraffin, calcium stearate, and oleamide; the tackifier is two of glycerol, sorbitol, rosin, rosin glyceryl ester, and pentaerythritol rosin ester; and the antioxidant is one of antioxidant B215, antioxidant 168, and antioxidant B225.
6. The method for preparing a star-shaped polylactic acid and its biodegradable polyester composite material based on PBAT / s-PLA according to claim 5, characterized in that, The filler is nano-calcium carbonate (n-CaCO3); the compatibilizer is PEG-400; the lubricant is stearic acid; the tackifier is a mixture of glycerin and sorbitol; and the antioxidant is antioxidant B215.
7. The method for preparing a biodegradable polyester composite material based on PBAT / s-PLA according to claim 4, characterized in that, The material temperature of the high-speed mixer is controlled at 85~95℃, the rotation speed is 5~20 Hz, and the stirring time is 20~40 min; the mass ratio of poly(butylene adipate-terephthalate), star-shaped polylactic acid, and thickener is 350~450:10~100:3:9, the material temperature of the high-speed mixer is controlled at 85~95℃, the rotation speed is 5~20 Hz, and the stirring time is continued for 5~15 min.
8. The method for preparing a star-shaped polylactic acid and its biodegradable polyester composite material based on PBAT / s-PLA according to claim 4, characterized in that, In step 2), the temperatures of each zone of the small twin-screw extruder are as follows: Zone 1 140~145℃, Zone 2 145~150℃, Zone 3 145~150℃, Zone 4 150~155℃, and Zone 5 150~155℃.
9. A biodegradable wrapping film, characterized in that, The biodegradable polyester composite material described in claim 3 is placed in a small blown film machine, and the temperature of each zone is controlled to blow film to obtain a biodegradable winding film.
10. A biodegradable wrapping film according to claim 9, characterized in that, The temperatures of each zone of the small blown film machine are as follows: Zone 1 140~145℃, Zone 2 145~150℃, Zone 3 145~150℃, Zone 4 150~155℃, Zone 5 150~155℃, and the thickness of the stretch film is 0.02~0.025 mm.