Lignin-modified PBS biodegradable plastic and preparation method thereof
By blending graded lignin with PBS using ethyl acetate and adding thioctic acid, the problems of complex modification process and insufficient ductility of lignin-modified PBS plastics were solved, achieving efficient and environmentally friendly improvement of mechanical properties and simplifying the preparation process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGDONG UNIV OF TECH
- Filing Date
- 2024-09-06
- Publication Date
- 2026-05-19
AI Technical Summary
The existing technology for modifying lignin-modified PBS plastics involves complex modification processes, a variety of components, and does not effectively improve the material's ductility. Furthermore, the reaction is highly toxic and not environmentally friendly.
A lignin-modified PBS plastic with a specific structure and molecular weight was prepared by blending graded lignin with ethyl acetate and adding thioctic acid to improve the compatibility of lignin and PBS through hydrogen bonding and synergistic effects.
It significantly improves the mechanical properties of PBS composites, especially their ductility, while simplifying the preparation process, reducing energy consumption and toxicity, and aligning with green and sustainable development goals.
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Figure CN118909411B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of biodegradable plastics, and mainly relates to a lignin-modified PBS biodegradable plastic and its preparation method. Background Technology
[0002] With the rapid development of my country's economy, the consumption of single-use biodegradable plastic products in the market has been increasing year by year, reaching 653,400 tons in 2022. Polybutylene succinate (PBS) is a fully biodegradable plastic synthesized from raw materials such as butanediol and succinic acid. PBS has good degradability and biocompatibility, and is widely used in food packaging, medical devices, agricultural mulch films, and other fields, making it an environmentally friendly plastic material. PBS itself has high tensile strength but poor ductility; therefore, research on improving its mechanical properties and reducing costs through filler filling is of great significance to PBS research.
[0003] Lignin is the world's second most abundant biomass resource, possessing rich benzene ring structures, aliphatic and aromatic hydroxyl groups, and quinone groups, exhibiting excellent biocompatibility. Industrial lignin is a byproduct of the pulp and paper industry and biorefining industry, with huge production volumes but low utilization rates. Applying lignin to the preparation of PBS can effectively improve the mechanical properties of composite materials.
[0004] However, existing technologies for improving the mechanical properties of PBS using lignin often require modification of the lignin and the addition of various additives to improve the compatibility between lignin and PBS. CN106700442A discloses a lignin-modified PBS biodegradable plastic and its preparation method. This method involves blending composite-modified lignin, polybutylene succinate, and functional additives in different proportions to obtain a lignin-PBS composite plastic. However, this method has an overly complex composition, uses a large number of functional additives in the modification, and the composite material has low ductility, with an elongation at break of only 360%. CN109575534A discloses a biomass reinforcing agent, modified PBS material, and its preparation method. This method involves assembling modified lignin with a core-shell structure of polylactide-polybutyrolactone block copolymer to form a biomass reinforcing agent, which is then blended with PBS to obtain a modified PBS material. However, the preparation of this reinforcing agent requires the use of ethylene glycol dimethyl ether and formaldehyde, which are highly toxic and environmentally unfriendly. The modification time is too long, microwave radiation is also required, and the issue of material ductility is not addressed. Therefore, the existing technologies currently have the following problems: the modification process is complex and time-consuming; there are many types of components; the material's ductility has not been effectively improved and the reaction is highly toxic and not environmentally friendly. Summary of the Invention
[0005] In order to solve the problems existing in the prior art, the purpose of this invention is to provide a lignin-modified PBS biodegradable plastic.
[0006] Another object of the present invention is to provide a method for preparing lignin-modified PBS biodegradable plastic.
[0007] Another object of the present invention is to provide an application of lignin-modified PBS biodegradable plastic in the preparation of film products, medical products, packaging materials, tableware, and bio-foaming materials.
[0008] The above-mentioned objective of the present invention is achieved through the following technical solution:
[0009] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS and 5-10 parts ethyl acetate graded lignin.
[0010] This invention utilizes ethyl acetate fractionation to effectively homogenize lignin, yielding lignin with specific structures and molecular weights. Ethyl acetate dissolves lignin with lower molecular weights and higher phenolic hydroxyl and methoxyl content, effectively reducing the polymer dispersibility index (PDI) of lignin and resulting in a more uniform molecular weight distribution. The higher content of phenolic hydroxyl and other polar functional groups in ethyl acetate-fractionated lignin forms hydrogen bonds with PBS. The lower molecular weight reduces steric hindrance and chain length during stretching, facilitating the penetration of ethyl acetate-fractionated lignin into the PBS molecular chain, thereby enhancing the non-covalent bond interaction between ethyl acetate-fractionated lignin and PBS. The lower weight-average molecular weight also helps reduce lignin aggregation, improving the compatibility between lignin and PBS, and consequently enhancing the mechanical properties of the PBS composite material, especially the ductility of PBS.
[0011] Solvent fractionation is an effective method for homogenizing lignin. By fractionating lignin according to different solvent solubility parameters, lignin components with low dispersibility and high reactivity can be obtained. As the molecular weight decreases, the phenolic hydroxyl and methoxyl groups in lignin gradually increase, while the aliphatic hydroxyl content gradually decreases with decreasing molecular weight.
[0012] Specifically, the method for preparing the ethyl acetate graded lignin includes the following steps:
[0013] Alkali lignin was mixed with ethyl acetate, filtered, and the filtrate was concentrated by rotary evaporation to obtain the ethyl acetate graded lignin.
[0014] More specifically, the weight-average molecular weight of the ethyl acetate graded lignin is 880–1100, and the number-average molecular weight is 530–680.
[0015] More specifically, the mass ratio of the alkali lignin to ethyl acetate is 1:7 to 11.
[0016] More specifically, the mixing time between alkali lignin and ethyl acetate is 2–3 hours.
[0017] The ethyl acetate solvent collected by rotary evaporation can be recovered and reused.
[0018] Specifically, the lignin-modified PBS biodegradable plastic also includes thioctic acid.
[0019] Lipoic acid melts at high temperature and undergoes disulfide bond exchange to form linear polymer chains. These chains form strong hydrogen bonds with ethyl acetate-based lignin and the PBS matrix, promoting interfacial fusion, improving interfacial compatibility, and further enhancing the mechanical properties of the composite material.
[0020] More specifically, the lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 5-10 parts ethyl acetate graded lignin, and 1-5 parts lipoic acid.
[0021] More specifically, the lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 7.5 parts ethyl acetate graded lignin, and 1-5 parts lipoic acid.
[0022] Preferably, the lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 7.5 parts ethyl acetate graded lignin, and 3-4 parts lipoic acid.
[0023] Insufficient lipoic acid may not be enough to form an effective reinforcing structure and could even interfere with the interaction between lignin and PBS, leading to a decrease in mechanical properties. As the mass of lipoic acid increases, ethyl acetate-graded lignin and lipoic acid work synergistically to improve the mechanical properties of PBS plastics.
[0024] A method for preparing the lignin-modified PBS biodegradable plastic includes the following steps:
[0025] The lignin-modified PBS biodegradable plastic is obtained by mixing PBS and ethyl acetate graded lignin.
[0026] Specifically, the preparation method of lignin-modified PBS biodegradable plastic includes the following steps:
[0027] PBS, ethyl acetate, graded lignin, and lipoic acid are mixed to obtain lignin-modified PBS biodegradable plastic with added lipoic acid.
[0028] Specifically, the mixing temperature is 130℃~150℃, the mixing time is 20~40min, and the mixing speed is 70~100rpm.
[0029] Excessive mixing temperature or prolonged mixing time will degrade the performance of PBS.
[0030] Appropriate rotation speed will allow lignin and thioctic acid to be more evenly dispersed in PBS, while excessive rotation speed will reduce the tensile properties of the composite material.
[0031] Application of a lignin-modified PBS biodegradable plastic in the preparation of film products, medical supplies, packaging materials, tableware, and bio-foaming materials.
[0032] Compared with the prior art, the present invention has the following beneficial effects:
[0033] In this invention, the polar functional groups of ethyl acetate graded lignin form hydrogen bonds with PBS. Its low molecular weight reduces steric hindrance and chain segment length during stretching, reduces lignin aggregation, improves the compatibility of lignin and PBS, thereby improving the mechanical properties of PBS composite materials and significantly improving the ductility of PBS.
[0034] The lignin-modified PBS biodegradable plastic provided by this invention has good mechanical properties, UV resistance, antibacterial properties, photothermal conversion properties, and photothermal antibacterial properties.
[0035] The method for preparing lignin-modified PBS biodegradable plastic of the present invention is simple, low-energy, low-toxic, and the solvent is recyclable, which saves resources and energy to a certain extent and responds to the goal of green and sustainable development. Attached Figure Description
[0036] Figure 1 The stress-strain diagrams are for the PBS plastics obtained in the embodiments and comparative examples of the present invention.
[0037] Figure 2 The stress-strain diagrams are shown for the PBS plastics obtained in Example 6 and Comparative Example 1 of this invention before and after thermal aging at 60°C.
[0038] Figure 3 The stress-strain diagrams of the PBS plastics obtained in Example 6 and Comparative Example 1 before and after ultraviolet irradiation are shown.
[0039] Figure 4 The images show the photothermal effects of Embodiments 2, 3, and 6 of the present invention and Comparative Example 1.
[0040] Figure 5 The images show the ultraviolet transmittance of Examples 2, 6, Comparative Example 1, and Comparative Example 5 of the present invention.
[0041] Figure 6 The diagrams show the antibacterial and photothermal antibacterial properties of Examples 2, 6, Comparative Examples 1 and 5 of this invention. Detailed Implementation
[0042] The following examples further illustrate the bioplastic film of the present invention, its preparation method, and its application. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following examples. Unless otherwise specified, the experimental methods in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.
[0043] The preparation methods of ethyl acetate fractionated lignin in the embodiments of the present invention and Comparative Example 3 include the following steps:
[0044] Industrial alkali lignin (from Shandong Sun Paper Industry Co., Ltd.) was dissolved in ethyl acetate solvent and stirred at room temperature for 2.5 h. The mass ratio of industrial alkali lignin to ethyl acetate solvent was 1:9. The mixed solution was filtered, and the filtrate was concentrated by rotary evaporation at 40 °C and dried to obtain graded ethyl acetate lignin.
[0045] The weight-average molecular weight of the ethyl acetate fractionated lignin prepared was 880, and the number-average molecular weight was 530.
[0046] Example 1
[0047] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS (manufacturer: Xinjiang Lanshan Tunhe Technology Co., Ltd., brand name: TH803S), and 5 parts ethyl acetate graded lignin.
[0048] The method for preparing the lignin-modified PBS biodegradable plastic includes the following steps:
[0049] Turn on the heating and rotating devices of the open mill, set the heating temperature to 135℃ and the roller speed to 90 rpm, and melt the PBS. Pour ethyl acetate graded lignin onto the molten PBS in small amounts multiple times, mixing with a spatula for 10 minutes. Turn off the heating device, and allow the mixture to cool slowly at room temperature while maintaining a speed of 90 rpm before removing it from the roller. Place the resulting composite material onto a dumbbell-shaped mold, and melt it at 135℃ for 5 minutes using a flatbed hot press. Then, pressurize to 20 MPa, melt for 10 minutes, turn off the heating device, turn on the circulating water pump to cool, and then demold.
[0050] Example 2
[0051] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS and 7.5 parts ethyl acetate graded lignin.
[0052] The preparation steps are the same as in Example 1.
[0053] Example 3
[0054] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS and 10 parts ethyl acetate graded lignin.
[0055] The preparation steps are the same as in Example 1.
[0056] Example 4
[0057] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 7.5 parts ethyl acetate graded lignin, and 1 part lipoic acid.
[0058] The preparation steps are the same as in Example 1.
[0059] Example 5
[0060] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 7.5 parts ethyl acetate graded lignin, and 2 parts lipoic acid.
[0061] The preparation steps are the same as in Example 1.
[0062] Example 6
[0063] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 7.5 parts ethyl acetate graded lignin, and 3 parts lipoic acid.
[0064] The preparation steps are the same as in Example 1.
[0065] Example 7
[0066] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 7.5 parts ethyl acetate graded lignin, and 4 parts lipoic acid.
[0067] The preparation steps are the same as in Example 1.
[0068] Example 8
[0069] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 7.5 parts ethyl acetate graded lignin, and 5 parts lipoic acid.
[0070] The preparation steps are the same as in Example 1.
[0071] Comparative Example 1
[0072] A biodegradable PBS plastic comprises the following components in parts by weight: 100 parts PBS.
[0073] The preparation steps are the same as in Example 1.
[0074] Comparative Example 2
[0075] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS and 7.5 parts ungraded lignin.
[0076] The preparation steps are the same as in Example 1.
[0077] Comparative Example 3
[0078] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS, 7.5 parts ethyl acetate graded lignin, and 5 parts epoxidized soybean oil.
[0079] The preparation steps are the same as in Example 1.
[0080] Comparative Example 4
[0081] The preparation method of ethanol-graded lignin in this comparative example includes the following steps:
[0082] Industrial alkali lignin (from Shandong Sun Paper Industry Co., Ltd.) was dissolved in ethanol solvent and stirred at room temperature for 2.5 h. The mass ratio of industrial alkali lignin to ethanol solvent was 1:9. The mixed solution was filtered, and the filtrate was concentrated by rotary evaporation at 50 °C and dried to obtain ethanol-graded lignin.
[0083] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS and 7.5 parts ethanol-graded lignin.
[0084] The preparation steps are the same as in Example 1.
[0085] Comparative Example 5
[0086] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS and 3 parts lipoic acid.
[0087] The preparation steps are the same as in Example 1.
[0088] Comparative Example 6
[0089] The preparation method of acetone-graded lignin in this comparative example includes the following steps:
[0090] Industrial alkali lignin (from Shandong Sun Paper Industry Co., Ltd.) was dissolved in acetone solvent and stirred at room temperature for 2.5 hours. The mass ratio of industrial alkali lignin to acetone solvent was 1:9. The mixed solution was filtered, and the filtrate was concentrated by rotary evaporation at 50°C and dried to obtain acetone-graded lignin.
[0091] A lignin-modified PBS biodegradable plastic comprises the following components in parts by weight: 100 parts PBS and 7.5 parts acetone-graded lignin.
[0092] The preparation steps are the same as in Example 1.
[0093] Performance testing
[0094] The examples and comparative examples require hot pressing for performance testing. The hot pressing process can be as follows: the mixed material is spread flat on a mold, hot-melted in a flat vulcanizing machine at 135°C for 5 minutes, then pressurized to 20MPa for 10 minutes, and then cooled and demolded.
[0095] Tensile property test: The PBS plastics obtained in the examples and comparative examples were used to prepare dumbbell-shaped specimens. The tensile properties of the specimens were tested, and the lifting speed of the clamp was 50 mm / min. -1 .
[0096] Heat aging test: The PBS plastics obtained in the examples and comparative examples were prepared into dumbbell-shaped specimens and placed in an oven at 60°C for heat aging. The tensile properties of the specimens were then tested, with the clamp rising at a speed of 50 mm / min. -1 .
[0097] UV resistance test: The PBS plastics obtained from the examples and comparative examples were prepared into rectangular strips with a thickness of 10 μm and placed in a UV-Vis spectrophotometer for scanning. The scanning range was set to 200-600 nm.
[0098] Antibacterial test: The PBS plastic obtained in the examples and comparative examples was prepared into discs with a thickness of 0.8 mm and a diameter of 1 cm. The material was mixed with 1 ml of PBS with a density of 10... 6 The Escherichia coli culture medium and Staphylococcus aureus culture medium were co-cultured at 37℃ for 24 h. The OD value of the culture medium was measured by an enzyme-linked immunosorbent assay (ELISA) reader, and the inhibition rate was calculated.
[0099] Photothermal antibacterial test: The PBS plastic obtained in the examples and comparative examples was prepared into circular sheets with a thickness of 0.8 mm and a diameter of 1 cm. The material was mixed with 200 μl of PBS with a density of 10... 7 The bacterial culture was irradiated with a concentration of 100 cells / ml under a near-infrared lamp for 10 minutes. After 100 μl of photothermal treatment, the bacterial culture was added to 900 μl of broth culture medium. The material and culture medium were co-cultured at a constant temperature of 37℃ for 24 hours. The OD value of the culture medium was measured by an enzyme-linked immunosorbent assay (ELISA) reader, and the inhibition rate was calculated.
[0100] The formula for calculating the antibacterial rate is:
[0101]
[0102] The tensile strength and elongation at break test results of the examples and comparative examples are shown in Table 1 below. Figure 1 As shown:
[0103] Table 1. Tensile strength and elongation at break test results of the examples and comparative examples.
[0104]
[0105]
[0106] From Table 1 and Figure 1 The data shows that ethyl acetate-graded lignin can effectively improve the ductility of PBS. The tensile strength of the composite material obtained by blending ethyl acetate lignin with PBS can reach over 32 MPa, and the elongation at break can reach over 526%. The composite material obtained by blending ethyl acetate lignin, lipoic acid, and PBS has a tensile strength as high as 35.84 MPa and an elongation at break as high as 1304%, which is 28 times higher than that of pure PBS. Figure 1 The toughness of the composite material was calculated by integrating the area of the stress-strain curve. The calculated area was 11.41 for Comparative Example 1, 165.54 for Example 2, and 351.15 for Example 6. Example 2 showed a 14.5-fold increase in toughness compared to Comparative Example 1, and Example 6 showed a 30.78-fold increase in toughness compared to Comparative Example 1. This indicates that the synergistic effect of ethyl acetate-graded lignin and lipoic acid in this invention significantly improves the toughness of PBS.
[0107] Comparative Example 1 and Example 2 show that the addition of extracted lignin significantly improves the tensile properties of PBS. Example 6 shows that after the addition of lipoic acid, the polymerization of lipoic acid at high temperature to form polylipoic acid not only improves the dispersion of lignin in PBS, but also forms strong hydrogen bonds with lignin, creating a tightly integrated network structure between PBS, lignin, and polylipoic acid, further enhancing the mechanical properties of the PBS composite material. Examples 2 and 4-5 show that the addition of lipoic acid to the ethyl acetate fractionated lignin and PBS system leads to a decrease in elongation at break. However, this is because the amount of lipoic acid is too small to form an effective reinforcing structure, and may even interfere with the interaction between lignin and PBS, resulting in a decrease in mechanical properties. Therefore, the mass ratio of PBS:extracted lignin:lipoic acid needs to be controlled within the range of 100:7.5:(3-4) for ethyl acetate fractionated lignin and lipoic acid to have a synergistic effect.
[0108] As can be seen from Comparative Examples 4, 6 and 2, the weight-average molecular weight of ethanol-graded lignin is 3440 and the number-average molecular weight is 1690; the weight-average molecular weight of acetone-graded lignin is 3680 and the number-average molecular weight is 1260. Due to the large molecular weight of both, the elongation at break of the composite material is low. Ethanol-graded lignin and acetone-graded lignin cannot effectively improve the ductility of the PBS composite material.
[0109] Figure 2 These are stress-strain diagrams of the PBS plastics obtained in Example 6 and Comparative Example 1 before and after heat aging at 60°C. Figure 2 It is evident that the mechanical properties of the modified PBS plastic after heat aging are reduced, but still remain higher than those of PBS plastic. This indicates that the synergistic effect of ethyl acetate graded lignin and lipoic acid can improve the thermal stability of PBS composite materials, thereby increasing the service life of PBS plastic.
[0110] Figure 3 These are stress-strain diagrams of the PBS plastics obtained in Example 6 and Comparative Example 1 before and after ultraviolet irradiation. Figure 3 It is evident that the mechanical properties of the modified PBS plastic after UV irradiation decreased, but remained higher than those of PBS plastic, indicating that the synergistic effect of ethyl acetate graded lignin and lipoic acid can improve the UV resistance of PBS composite materials.
[0111] Figure 4 These are photothermal effect diagrams of Examples 2, 3, and 6, and Comparative Example 1. (From...) Figure 4 It is known that the addition of ethyl acetate to grade lignin imparts photothermal conversion properties to the modified PBS material, enabling it to convert near-infrared light irradiation into heat, thereby achieving a sterilization effect.
[0112] Figure 5 These are the UV transmittance maps of Examples 2 and 6, and Comparative Examples 1 and 5. (From...) Figure 5 It is evident that the ethyl acetate graded lignin-modified PBS plastic provided by this invention has good ultraviolet shielding ability, indicating that it has excellent UV resistance.
[0113] Figure 6 These are antibacterial and photothermal antibacterial diagrams for Examples 2, 6, Comparative Examples 1, and 5. (From...) Figure 6 It is evident that the modified PBS plastic provided by this invention exhibits good antibacterial effects against Escherichia coli and Staphylococcus aureus. Lignin can disrupt the cell wall and cell membrane structures of bacteria, thereby destroying them. Alpha-lipoic acid, as a potent antioxidant, can scavenge free radicals, reduce oxidative stress, and thus inhibit bacterial growth. The photothermal effect of lignin can raise the material temperature, effectively killing bacteria and achieving an antibacterial effect.
[0114] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A lignin-modified PBS biodegradable plastic, characterized in that, The components include the following parts by weight: 100 parts PBS, 5-10 parts graded lignin in ethyl acetate, and 1-5 parts lipoic acid; The method for preparing the ethyl acetate graded lignin includes the following steps: Alkali lignin in a mass ratio of 1:7 to 11 was mixed with ethyl acetate, filtered, and the filtrate was concentrated by rotary evaporation to obtain the ethyl acetate graded lignin.
2. The lignin-modified PBS biodegradable plastic according to claim 1, characterized in that, The components include the following parts by weight: 100 parts PBS, 7.5 parts graded lignin in ethyl acetate, and 1-5 parts lipoic acid.
3. A method for preparing lignin-modified PBS biodegradable plastic as described in any one of claims 1 to 2, characterized in that, Includes the following steps: PBS, ethyl acetate, graded lignin, and lipoic acid are mixed to obtain the lignin-modified PBS biodegradable plastic.
4. The method for preparing lignin-modified PBS biodegradable plastic according to claim 3, characterized in that, The mixing temperature is 130℃~150℃, the mixing time is 20~40min, and the mixing speed is 70~100rpm.
5. The application of the lignin-modified PBS biodegradable plastic as described in any one of claims 1 to 2 in the preparation of film products, medical products, packaging materials, tableware, and bio-foaming materials.