An antibacterial biodegradable multi-block copolyester and its preparation method and application

Abstract

The application discloses an antibacterial biodegradable multi-block copolyester and a preparation method and application thereof. Bio-based dimethyl 2,5-furan dicarboxylate (DMFD), dihydric alcohol and a novel high-heat-resistant heat-resistant reactive [CmSIPA] antibacterial agent with a double aromatic ring structure are first synthesized into OX[CmSIPA] (antibacterial agent dimethyl dicarboxylic acid dihydric alcohol ester prepolymer) and OXF (2,5-furan dicarboxylic acid dihydric alcohol ester prepolymer) through ester exchange reaction. Then, bio-based polytetramethylene ether glycol (PTMEG) is added into the two prepolymers to perform polycondensation reaction. After the reaction is completed, the melt product of the obtained copolyester flows into the feeding port of an extruder through the discharge port of a reaction kettle, is extruded, cooled and granulated through the extruder, and the antibacterial biodegradable multi-block copolyester is obtained. The obtained polyester has excellent antibacterial property, gas barrier property, biodegradability, thermal stability and mechanical property, and can be widely used in the fields of packaging, containers, medicine, medical treatment, protection, textiles, sports, transportation, electronic appliances and the like.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable polyester preparation, specifically relating to an antibacterial biodegradable multiblock copolyester, its preparation method, and its application. Background Technology

[0002] Polyester is one of the most promising polymer materials, second only to polyolefins in total output. It is widely used in packaging, textiles, sports, transportation, medical, electronics and other products that come into close contact with the human body. Developing polyester with antibacterial function can help block the spread of bacteria, reduce the risk of bacterial infection, and reduce the use of antibiotics, which is of great significance.

[0003] Currently, antibacterial polyesters are mainly prepared by physically blending inorganic antibacterial agents such as nano-silver and nano-zinc oxide. However, the antibacterial properties of these polyesters originate from the diffusion and release of the antibacterial agents, and their antibacterial properties are lost once the antibacterial agents are released, lacking long-lasting antibacterial capabilities. Furthermore, inorganic antibacterial agents generally possess significant biotoxicity, limiting their application. The most common methods for large-scale synthesis of commercial polyesters are esterification and polycondensation. Covalently binding organic antibacterial agents to the polyester backbone through co-condensation not only imparts durable antibacterial properties but also effectively reduces the biotoxicity of the antibacterial agents, representing the future direction of antibacterial polyester development. However, due to the high reaction temperatures of esterification and polycondensation, the thermal stability of organic antibacterial agents is generally poor, failing to meet the temperature requirements of esterification and polycondensation.

[0004] Quaternary ammonium salts are among the most widely used organic antibacterial agents, possessing broad-spectrum antibacterial activity. However, quaternary ammonium salts are prone to decomposition at high temperatures and have poor thermal stability, failing to meet the temperature requirements for melt polycondensation.

[0005] Currently, the vast majority of polyesters, such as PBT, PET, PBF, PEF, and PPF, are not biodegradable and are discarded at the end of their service life, causing serious environmental pollution problems. Compared with petroleum-based polyesters such as PBT and PET, commercially available biodegradable polyesters such as PCL, PPC, PLA, PBS, and PBAT still have room for improvement in terms of performance, especially when used as packaging, structural, and engineering materials. The lack of aromatic groups or rigid units in their chemical structure, as well as low crystallinity, makes the shortcomings of biodegradable polyesters in terms of barrier and mechanical properties particularly apparent. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] Beneficial effects of this invention:

[0008] (1) This invention successfully prepared a multi-block copolyester with excellent mechanical properties, gas barrier properties, biodegradability, antibacterial properties, and thermal stability. The excellent properties are attributed to the type of monomers used in the polymerization process. The antibacterial agent used has significantly higher heat resistance than existing antibacterial agents. During the polymerization process, the antibacterial agent and the monomers of the synthetic polyester were successfully embedded into the prepolymer backbone through esterification and transesterification reactions. Then, antibacterial polyester with antibacterial groups embedded in the backbone was obtained through polycondensation. This not only endows the polyester with long-lasting antibacterial properties but also effectively reduces the biotoxicity of the antibacterial agent. Characterization of thermal stability and antibacterial activity revealed that the thermal decomposition temperature is higher than 350℃, and the antibacterial rate is high, which can meet the requirements for heat resistance and antibacterial activity of the antibacterial agent. This reaction uses only catalyst on the order of 10 2 ~10 3 An antibacterial agent of ppm (1 ppm) can produce a polyester copolymer with long-lasting high antibacterial activity.

[0009] (2) The 2,5-furandicarboxylic acid dimethyl ester (DMFD) used in this invention is synthesized from the bio-based monomer 2,5-furandicarboxylic acid (FDCA). FDCA and petroleum-based terephthalic acid (PTA) both contain aromatic rings and two carboxylic acid groups and have similar chemical structures. However, compared with PTA, FDCA has greater rigidity and polarity. The mechanical properties, barrier properties, heat resistance properties and degradation properties of the synthesized polyester are significantly improved. In particular, the FDCA-based polyester is more outstanding in gas barrier properties.

[0010] (3) The bio-based polytetrahydrofuran ether diol (PTMEG) used in this invention is condensed to form a copolyester. PTMEG has a neatly arranged molecular structure, which gives it special properties. Its products exhibit excellent physical and mechanical properties. The PTMEG structure contains 4 methylene groups, which have a certain degree of chain segment flexibility. As a flexible soft segment in the copolyester, it has a certain toughening effect on the copolyester. In addition, the ether diol unit can enhance the degradation ability of the chain segment. In this invention, the PTMEG unit is introduced into the DMFD-based polyester, realizing the dual properties of degradation and toughening of PXA-PXF-PTMEG multiblock copolyester, and obtaining a biodegradable thermoplastic multiblock copolyester with excellent comprehensive performance.

[0011] (4) The PXA-PXF-PTMEG multiblock copolyester invented in this invention is a novel antibacterial and biodegradable multiblock copolyester, which has originality and innovation. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0013] Figure 1 This is a process flow diagram in an embodiment of the present invention. Detailed Implementation

[0014] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0015] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0016] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0017] Unless otherwise specified, all raw materials used in the examples are commercially available products.

[0018] Example 1

[0019] The preparation of the antibacterial and biodegradable PEA-PEF-PTMEG multiblock copolyester is as follows:

[0020] Step 1: Esterification and transesterification reactions

[0021] Preparation of OEA and OEF prepolymers: Dimethyl 2,5-furandicarboxylate (DMFD) and ethylene glycol (EG) were added to a stainless steel reactor in a molar mass ratio of DMFD (mol):EDO (mol) = 1:2.5. 0.01 wt% of [C14SIPA] antibacterial agent, 0.15 wt% of tetrabutyl titanate catalyst, and 0.2 wt% of triphenyl phosphite phosphate stabilizer were added. The temperature was slowly raised to 180°C, and nitrogen gas was introduced. During the reaction, distilled methanol and water were removed. The reaction ended when the calculated amount of methanol and water distilled reached more than 98% of the theoretical value, yielding OEA and OEF prepolymers.

[0022] Step 2: Polycondensation reaction

[0023] Polytetramethylene ether glycol (PTMEG), OEA prepolymer, and OEF prepolymer were added to the reactor. The OEF prepolymer (wt%) and PTMEG (wt%) were measured by weight percentage as follows: OEF prepolymer (wt%):PTMEG (wt%) = 90:10. Additionally, 0.2 wt% of antimony trioxide, 0.3 wt% of triphenyl phosphite as a stabilizer, and 0.3 wt% of sodium benzoate as a nucleating agent were added.

[0024] The temperature of the reactor was slowly raised to 230℃. The vacuum pump was turned on and the flow rate of nitrogen was adjusted to make the internal pressure less than 100Pa. After the viscosity stabilized, the reaction was stopped. High-purity nitrogen was introduced to restore the pressure in the reactor to normal pressure. The resulting copolyester melt product flowed into the extruder inlet through the reactor outlet. After extrusion, cooling and granulation, an antibacterial and biodegradable PEA-PEF-PTMEG multiblock copolyester was obtained, labeled as PEA-PEF-PTMEG10.

[0025] Example 2

[0026] The preparation of the antibacterial and biodegradable PEA-PEF-PTMEG15 multiblock copolyester is as follows:

[0027] Step 1: Esterification and transesterification reactions

[0028] Preparation of OEA and OEF prepolymers: Dimethyl 2,5-furandicarboxylate (DMFD) and ethylene glycol (EG) were added to a stainless steel reactor in a molar mass ratio of DMFD (mol):EG (mol) = 1:2.5. 0.15 wt% of [C14SIPA] antibacterial agent, 0.15 wt% of tetrabutyl titanate catalyst, and 0.2 wt% of triphenyl phosphite stabilizer were added. The temperature was slowly raised to 180°C, and nitrogen gas was introduced. During the reaction, distilled methanol and water were removed. The reaction ended when the calculated amount of methanol and water distilled reached more than 98% of the theoretical value, thus obtaining the OEA and OEF prepolymers.

[0029] Step 2: Polycondensation reaction

[0030] Polytetramethylene ether glycol (PTMEG), OEA prepolymer, and OEF prepolymer were added to the reactor. The OEF prepolymer (wt%) and PTMEG (wt%) were measured by weight percentage as follows: OEF prepolymer (wt%):PTMEG (wt%) = 85:15. 0.15 wt% tetrabutyl titanate catalyst, 0.2 wt% triphenyl phosphite stabilizer, and 0.3 wt% sodium benzoate nucleating agent were also added.

[0031] The temperature of the reactor was slowly raised to 230℃. The vacuum pump was turned on and the flow rate of nitrogen was adjusted to make the internal pressure less than 100Pa. After the viscosity reached a certain value, the reaction was stopped. High-purity nitrogen was introduced to restore the pressure in the reactor to normal pressure. The resulting copolyester melt product flowed into the extruder inlet through the reactor outlet. After extrusion, cooling and granulation, an antibacterial and biodegradable PEA-PEF-PTMEG multiblock copolyester was obtained, labeled as PEA-PEF-PTMEG15.

[0032] Example 3

[0033] The preparation of the antibacterial and biodegradable PEA-PEF-PTMEG20 multiblock copolyester is as follows:

[0034] Step 1: Esterification and transesterification reactions

[0035] Preparation of OEA and OEF prepolymers: Dimethyl 2,5-furandicarboxylate (DMFD) and ethylene glycol (EG) were added to a stainless steel reactor in a molar mass ratio of DMFD (mol):EG (mol) = 1:2.5. 0.2 wt% of [C14SIPA] antibacterial agent, 0.15 wt% of tetrabutyl titanate catalyst, and 0.2 wt% of triphenyl phosphite phosphate stabilizer were added. The temperature was slowly raised to 180°C, and nitrogen gas was introduced. During the reaction, distilled methanol and water were removed. The reaction ended when the calculated amount of methanol and water distilled reached more than 98% of the theoretical value, yielding OEA and OEF prepolymers.

[0036] Step 2: Polycondensation reaction

[0037] Polytetramethylene ether glycol (PTMEG), OEA prepolymer, and OEF prepolymer were added to a reactor at a weight percentage of 80:20 (OEF prepolymer wt%) to PTMEG wt%). 0.15 wt% tetrabutyl titanate catalyst, 0.2 wt% triphenyl phosphite phosphate stabilizer, and 0.4 wt% sodium benzoate nucleating agent were also added. The reactor temperature was slowly raised to 230°C. The vacuum pump was turned on, and nitrogen gas was introduced at an adjusted flow rate to maintain an internal pressure below 100 Pa. Once the viscosity reached a certain value, the reaction was stopped. High-purity nitrogen was introduced to restore the reactor pressure to atmospheric pressure. The resulting copolyester melt flowed from the reactor outlet into the extruder inlet. After extrusion, cooling, and granulation, an antibacterial and biodegradable PEA-PEF-PTMEG multiblock copolyester was obtained, labeled PEA-PEF-PTMEG60.

[0038] Example 4

[0039] The preparation of the antibacterial and biodegradable PBA-PBF-PTMEG20 multiblock copolyester is as follows:

[0040] Step 1: Esterification and transesterification reactions

[0041] Preparation of OBA and OBF prepolymers: Dimethyl 2,5-furandicarboxylate (DMFD) and 1,4-butanediol (BDO) were added to a stainless steel reactor in a molar mass ratio of DMFD (mol):BDO (mol) = 1:2.5. 0.15 wt% of [C14SIPA] antibacterial agent, 0.2 wt% of antimony trioxide catalyst, and 0.3 wt% of triphenyl phosphate phosphite stabilizer were added. The temperature was slowly raised to 170°C, and nitrogen gas was introduced. During the reaction, distilled methanol and water were removed. The reaction ended when the calculated amount of methanol and water distilled reached more than 98% of the theoretical value, yielding OBA and OBF prepolymers.

[0042] Step 2: Polycondensation reaction

[0043] Polytetramethylene ether glycol (PTMEG), OBA prepolymer, and OBF prepolymer were added to a reactor at a weight percentage of 80:20 (OBF prepolymer wt%) to PTMEG wt%). 0.2 wt% of antimony trioxide catalyst, 0.3 wt% of triphenyl phosphite phosphate stabilizer, and 0.2 wt% of sodium benzoate nucleating agent were added. The reactor temperature was slowly raised to 220°C. The vacuum pump was turned on, and nitrogen flow rate was adjusted to maintain an internal pressure below 100 Pa. Once the viscosity reached a certain value, the reaction was stopped. High-purity nitrogen was introduced to restore the reactor pressure to atmospheric pressure. The resulting copolyester melt flowed from the reactor outlet into the extruder inlet. After extrusion, cooling, and granulation, an antibacterial and biodegradable PBA-PBF-PTMEG multiblock copolyester was obtained, labeled PBA-PBF-PTMEG20.

[0044] Example 5

[0045] The preparation of the antibacterial and biodegradable PNPA-PNPF-PTMEG multiblock copolyester is as follows:

[0046] Step 1: Esterification and transesterification reactions

[0047] Preparation of ONPA and OEF prepolymers: Dimethyl 2,5-furandicarboxylate (DMFD) and neopentyl glycol (NPG) were added to a stainless steel reactor in a molar mass ratio of DMFD (mol):NPG (mol) = 1:2.5. 0.1 wt% of [C14SIPA] antibacterial agent, 0.3 wt% of stannous octoate catalyst, and 0.3 wt% of triphenyl phosphite phosphate stabilizer were added. The temperature was slowly raised to 180°C, and nitrogen gas was introduced. During the reaction, distilled methanol and water were removed. The reaction ended when the calculated amount of methanol and water distilled reached more than 98% of the theoretical value, yielding ONPA and ONPF prepolymers.

[0048] Step 2: Polycondensation reaction

[0049] Polytetramethylene ether glycol (PTMEG), ONPA prepolymer, and ONPF prepolymer were added to a reactor. The ratio of ONPF prepolymer (wt%) to PTMEG (wt%) was 70:30 by weight. A total of 0.3 wt% stannous octoate catalyst, 0.3 wt% triphenyl phosphite phosphate stabilizer, and 0.45 wt% sodium benzoate nucleating agent were added. The reactor temperature was slowly raised to 240°C. The vacuum pump was turned on, and nitrogen gas was introduced at an adjusted flow rate to maintain an internal pressure below 100 Pa. Once the viscosity reached a certain value, the reaction was stopped. High-purity nitrogen was introduced to restore the pressure in the reactor to atmospheric pressure. The resulting copolyester melt product flowed from the reactor outlet into the extruder inlet. After extrusion, cooling, and granulation, an antibacterial and biodegradable PNPA-PNPF-PTMEG multiblock copolyester was obtained, labeled PNPA-PNPF-PTMEG70.

[0050] Comparative Example 1

[0051] The preparation method of PEA-PET-PTMEG multiblock copolyester is as follows:

[0052] Step 1: Esterification and transesterification reactions

[0053] Preparation of OEA prepolymer and OET (1,4-butanediol terephthalate prepolymer): Terephthalic acid (PTA) and ethylene glycol (EG) were added to a stainless steel reactor in a molar mass ratio of PTA (mol):EG (mol) = 1:2.5. 0.15 wt% of [C14SIPA] antibacterial agent, 0.15 wt% of tetrabutyl titanate catalyst, and 0.2 wt% of triphenyl phosphite phosphate stabilizer were added. The temperature was slowly raised to 220°C, and nitrogen gas was introduced. During the reaction, distilled methanol and water were removed. The reaction ended when the calculated amount of methanol and water distilled reached more than 98% of the theoretical value, yielding OEA prepolymer and OET prepolymer.

[0054] Step 2: Polycondensation reaction

[0055] Polytetramethylene ether glycol (PTMEG), OEA prepolymer, and OET prepolymer were added to a reactor at a weight percentage of 60:40 (OET prepolymer wt%) to PTMEG wt%). 0.15 wt% tetrabutyl titanate catalyst, 0.2 wt% triphenyl phosphite phosphate stabilizer, and 0.3 wt% sodium benzoate nucleating agent were also added. The reactor temperature was slowly raised to 250°C. The vacuum pump was turned on, and nitrogen gas was introduced at an adjusted flow rate to maintain an internal pressure below 100 Pa. Once the viscosity reached a certain value, the reaction was stopped. High-purity nitrogen was introduced to restore the reactor pressure to atmospheric pressure. The resulting copolyester melt product flowed from the reactor outlet into the extruder inlet. After extrusion, cooling, and granulation, a PEA-PET-PTMEG multiblock copolyester was obtained, labeled PEA-PBT-PTMEG15.

[0056] The difference between Comparative Example 1 and Example 2 is that in Comparative Example 1, dimethyl 2,5-furandicarboxylate (DMFD) in Example 2 was replaced with terephthalic acid (PTA) to synthesize PEA-PET-PTMEG40.

[0057] Comparative Example 2

[0058] The antibacterial PEA-PEF copolyester was prepared as follows:

[0059] Step 1: Esterification and transesterification reactions

[0060] Preparation of OEA and OEF prepolymers: Dimethyl 2,5-furandicarboxylate (DMFD) and ethylene glycol (EG) were added to a stainless steel reactor in a molar mass ratio of DMFD (mol):EG (mol) = 1:2.5. 0.15 wt% of [C14SIPA] antibacterial agent, 0.15 wt% of tetrabutyl titanate catalyst, and 0.2 wt% of triphenyl phosphite phosphate stabilizer were added. The temperature was slowly raised to 180°C, and nitrogen gas was introduced. During the reaction, distilled methanol and water were removed. The reaction ended when the calculated amount of methanol and water distilled reached more than 98% of the theoretical value, yielding OEA and OEF prepolymers.

[0061] Step 2: Polycondensation reaction

[0062] The OEA and OEF prepolymers obtained in step one were added to a reactor, along with 0.15 wt% tetrabutyl titanate catalyst, 0.2 wt% triphenyl phosphite stabilizer, and 0.3 wt% sodium benzoate nucleating agent. The reactor temperature was slowly raised to 230°C, the vacuum pump was turned on, and nitrogen flow rate was adjusted to keep the internal pressure below 100 Pa. After the viscosity reached a certain value, the reaction was stopped, and high-purity nitrogen was introduced to restore the pressure in the reactor to atmospheric pressure. The resulting copolyester melt product flowed from the reactor outlet into the extruder inlet. After extrusion, cooling, and granulation, the antibacterial PEA-PEF copolyester was obtained.

[0063] The difference between Comparative Example 2 and Example 2 is that in Comparative Example 2, polytetramethylene ether glycol (PTMEG) was not added during the polycondensation reaction stage, and PEA-PEF copolyester was obtained after polycondensation.

[0064] Comparative Example 3

[0065] The preparation method of PEF-PTMEG multiblock copolyester is as follows:

[0066] Step 1: Transesterification

[0067] Preparation of OEF prepolymer: Dimethyl 2,5-furandicarboxylate (DMFD) and ethylene glycol (EG) were added to a stainless steel reactor in a molar mass ratio of DMFD (mol):EG (mol) = 1:2.5. 0.15 wt% tetrabutyl titanate catalyst and 0.2 wt% triphenyl phosphite phosphate stabilizer were added. The temperature was slowly raised to 180°C, and nitrogen gas was introduced. During the reaction, distilled methanol and water were removed. The reaction ended when the calculated amount of methanol and water distilled reached more than 98% of the theoretical value, yielding the OBF prepolymer.

[0068] Step 2: Polycondensation reaction

[0069] Polytetramethylene ether glycol (PTMEG) and OEF prepolymer were added to a reactor at a weight percentage of 85:15 (OEF prepolymer wt%):PTMEG wt%). 0.15 wt% tetrabutyl titanate catalyst, 0.2 wt% triphenyl phosphite phosphate stabilizer, and 0.4 wt% sodium benzoate nucleating agent were added. The reactor temperature was slowly raised to 230°C. The vacuum pump was turned on, and nitrogen flow rate was adjusted to maintain an internal pressure below 100 Pa. Once the viscosity reached a certain value, the reaction was stopped. High-purity nitrogen was introduced to restore the reactor pressure to atmospheric pressure. The resulting copolyester melt flowed from the reactor outlet into the extruder inlet. After extrusion (extruder temperature set to 245°C, screw speed set to 250 rpm / min), cooling, and granulation, PBF-PTMEG multiblock copolyester was obtained, labeled PBF-PTMEG60.

[0070] The difference between Comparative Example 3 and Example 2 is that no antibacterial agent was added in Comparative Example 2, and PBF-PTMEG60 block copolyester was synthesized through prepolymerization and polycondensation reaction.

[0071] The performance testing method is as follows:

[0072] Method for determining intrinsic viscosity: Dissolve 0.1-0.2g of sample in 25-50ml of phenol / tetrachloroethane mixed solvent (mass ratio 3 / 2), and test under constant temperature conditions of 25℃ using a semi-automatic viscometer and an Ubbelohde viscometer with a capillary inner diameter of 0.88mm.

[0073] Glass transition temperature (T) g ) and melting temperature (T) m Determination of thermal transition temperature of copolyester: The thermal transition temperature of the copolyester was obtained by DSC. Under a flow of N2 at 50 ml / min, the sample was first heated from -40℃ to 250℃ at a heating rate of 10℃ / min and held at 250℃ for 3 minutes to remove thermal history. The sample was then cooled to -40℃ at a heating rate of 10℃ / min and held for 3 minutes. Finally, the sample was reheated to 250℃ at a heating rate of 10℃ / min.

[0074] Thermal stability testing: The thermal stability of the copolyester was analyzed using TGA. Air and N2 atmospheres were used, with a purge rate of 50 ml / min. Approximately 10 mg of sample was heated to 800 °C at a heating rate of 20 °C / min.

[0075] Tensile and impact performance testing: The mechanical properties of the copolyester were tested using a universal testing machine. Tensile properties were tested according to ASTM D882. The specimens were prepared in a dumbbell shape with a neck thickness of 0.5 mm and a width of 2 mm. The tensile speed was 50 mm / min, and the original length before tensile testing was 20 mm. Each specimen was tested at least 6 times, and the average value was taken. The impact specimens were rectangular strips with a length of 80 mm, a width of 10 mm, and a thickness of 3.2 mm, and a 2 mm deep V-notch was pre-drilled on a notching machine. After being allowed to stand at room temperature for at least 24 hours to eliminate the influence of internal stress, a notched cantilever beam impact test was performed using a pendulum impact tester.

[0076] Degradation test: Enzymatic degradation experiments were conducted in phosphate buffer (pH = 7.4) at 37°C using porcine pancreatic lipase and Candida antarctica lipase B (CALB) enzymes, respectively. Every 4 days, the membrane was rinsed with distilled water and the degradation solution was replaced, and the membrane was dried to constant weight under vacuum at 40°C. The degradation rate was statistically analyzed based on the mass change of the copolyester during the degradation process.

[0077] Gas permeability test: The sample was hot-pressed into a film on a flat vulcanizing machine. The sample was placed between two smooth PTFE-coated cloths, with a 10cm x 10cm section cut out in the middle and a thickness of 0.2mm. The film was then melted at 250℃ for 10 minutes without pressure and then at 150 bar for 10 minutes under pressure on the flat vulcanizing machine. Finally, it was cooled to room temperature with cold water. The oxygen and carbon dioxide permeability coefficients of the sample were measured using a gas permeability meter under conditions of 1 atm, 23℃, and high-purity oxygen (99.99%) and carbon dioxide (99.99%). Three hot-pressed film samples were tested for each sample, and the average value was taken as the test result.

[0078] Bactericidal rate test: The antibacterial performance of the antibacterial agent is evaluated by measuring the proliferation of bacterial colonies using the plate count method according to the antibacterial test method specified in GB / T 20944.

[0079] The block copolyesters obtained in Examples 1-3 and Comparative Examples 1-3 were tested for mechanical properties, gas barrier properties, biodegradability, antibacterial properties and thermal stability. The results are shown in Table 1.

[0080] Table 1. Performance test results of block copolyesters obtained in Examples 1-5 and Comparative Examples 1-3.

[0081]

[0082]

[0083] As can be seen from the performance test results in Table 1, and as demonstrated in Examples 1-3, the PXA-PXF-PTMEG multiblock copolyester synthesized in this invention exhibits high glass transition temperature (Tg), thermal stability (5% decomposition temperature), elastic modulus (E), tensile strength (σ), elongation at break (ε), degradation rate, and antibacterial properties, while also possessing very low O2 permeability (PO2) and CO2 permeability (PCO2). The data show that this invention successfully prepared a multiblock copolyester with excellent mechanical properties, gas barrier properties, biodegradability, antibacterial properties, and thermal stability.

[0084] The superior performance described above is attributed to the polymer monomers used in this invention. The antibacterial agent used in this invention exhibits significantly higher heat resistance than existing antibacterial agents. During the polymerization process, the antibacterial agent and the monomers used to synthesize the polyester are successfully embedded into the prepolymer backbone through esterification and transesterification reactions. Then, antibacterial polyester with antibacterial groups embedded in the backbone is obtained through polycondensation. This reaction uses only catalyst on the order of 10⁻⁶. 2 ~10 3 An antibacterial agent of ppm (per ppm) can produce a polyester copolymer with long-lasting high antibacterial activity. Characterization of its thermal stability and antibacterial activity revealed that the thermal decomposition temperature is above 350℃, exhibiting excellent antibacterial properties that meet the requirements for heat resistance and antibacterial activity. In addition, the ionic properties of the sodium sulfonate group in the antibacterial agent give it strong hydrophilicity, which can enhance the hydrolysis and degradation ability of the copolyester segments.

[0085] The dimethyl 2,5-furandicarboxylate (DMFD) used in this invention is synthesized from the bio-based monomer 2,5-furandicarboxylic acid (FDCA). FDCA and petroleum-based terephthalic acid (PTA) both contain an aromatic ring and two carboxylic acid groups, exhibiting similar chemical structures. However, compared to PTA, FDCA possesses greater rigidity and polarity, resulting in significant improvements in the mechanical properties, gas barrier properties, heat resistance, and degradation performance of the synthesized polyesters. In particular, FDCA-based polyesters demonstrate superior gas barrier properties. The bio-based polytetrahydrofuran ether diol (PTMEG) used in this invention is condensed to form a copolyester. PTMEG's orderly arranged molecular structure endows it with unique properties, resulting in products exhibiting excellent physical and mechanical properties. The PTMEG structure contains four methylene groups, providing a degree of chain flexibility, acting as a flexible soft segment, and the ether diol unit enhances the degradation ability of the chain segments. In this invention, PTMEG units are introduced into DMFD-based polyesters, achieving both degradation and toughening properties in PXA-PXF-PTMEG multiblock copolyesters, resulting in a biodegradable thermoplastic multiblock copolyester with excellent overall performance.

[0086] The difference between Comparative Example 1 and Example 2 is that in Comparative Example 1, dimethyl 2,5-furandicarboxylate (DMFD) in Example 2 was replaced with terephthalic acid (PTA) to synthesize PEA-PET-PTMEG15. As can be seen from the O2 permeability coefficient (PO2) and CO2 permeability coefficient (PCO2) data in Table 1, the polyester synthesized in this invention has better barrier properties, which is due to the fact that 2,5-furandicarboxylic acid has greater rigidity and polarity than terephthalic acid.

[0087] The difference between Comparative Example 2 and Example 2 is that polytetramethylene ether glycol (PTMEG) was not added in the polycondensation reaction stage in Comparative Example 2. After polycondensation, PEA-PEF15 copolyester was obtained. As can be seen from Table 1, PTMEG can be used as a flexible soft segment, which makes the copolyester have high elongation at break and impact strength. This is due to the fact that the PTMEG structure contains 4 methylene groups, which have a certain degree of chain segment flexibility.

[0088] The difference between Comparative Example 3 and Example 2 is that Comparative Example 3 did not add an antibacterial agent. PEF-PTMEG15 block copolyester was synthesized through prepolymerization and polycondensation reactions. As shown in Table 1, the bactericidal rate against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) was 100% after adding the antibacterial agent, while Comparative Example 3, without the antibacterial agent, showed no bactericidal effect. This demonstrates that the antibacterial agent fully meets the requirements for heat resistance and antibacterial activity. Furthermore, the degradation ability of Example 3 was significantly higher than that of Comparative Example 3. This is attributed to the ionic properties of the sodium sulfonate group in the antibacterial agent, which gives it strong hydrophilicity and enables the hydrolysis and degradation of the copolyester segments.

[0089] Table 1 also lists the performance data of commercially available PET (bottle flake grade) and commercially available PEF (bottle flake grade). It can be seen that the PEA-PET-PTMEG copolyester synthesized in Examples 1-3 of this invention exhibits higher thermal stability, notched impact strength, degradability, bactericidal properties, and barrier properties than commercially available PET (bottle flake grade) and commercially available PEF (bottle flake grade). Furthermore, the intrinsic viscosity [η] of the copolyester synthesized in this invention is between 0.83 and 0.88, indicating the synthesis of a high molecular weight copolyester that meets the intrinsic viscosity requirements for bottle-grade flakes. When used in packaging containers, it exhibits excellent heat resistance and barrier properties, meeting the requirements for hot filling and pasteurization, and enabling large-scale application and demonstration in high-performance polyester container packaging.

[0090] To address the issues of biotoxicity, short-lasting antibacterial properties, and low thermal stability of the aforementioned antibacterial agents, the antibacterial agent used in this invention exhibits significantly higher heat resistance than existing antibacterial agents. In this invention, the antibacterial agent and monomers of the synthetic polyester are intercalated into the prepolymer backbone via esterification, followed by polycondensation to obtain an antibacterial polyester with antibacterial groups embedded in the backbone. This reaction uses only catalysts on the order of 10⁻⁶. 2 ~10 3 An antibacterial agent at ppm (per unit of volume) can produce a polyester copolymer with durable, high antibacterial activity. Characterization of its thermal stability and antibacterial activity revealed that the antibacterial activity was low above 350°C, which meets the requirements for heat resistance and antibacterial activity of antibacterial agents. Furthermore, the ionic properties of the sodium sulfonate group in the antibacterial agent give it strong hydrophilicity, enabling hydrolysis and degradation of the copolyester segments.

[0091] To address the issues of barrier properties, biodegradability, and antibacterial properties in existing polyesters, this invention successfully prepared an antibacterial and biodegradable thermal block copolyester through esterification, transesterification, and polycondensation reactions using bio-based dimethyl 2,5-furandicarboxylate (DMFD), diols, polytetrahydrofuran ether diol (PTMEG), and antibacterial monomers. The resulting polyester exhibits excellent mechanical properties, gas barrier properties, biodegradability, antibacterial properties, and thermal stability.

[0092] The PXA-PXF-PTMEG multiblock copolyester of the present invention is a novel antibacterial and biodegradable thermal block copolyester, which is original and innovative.

[0093] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A process for the preparation of an antibacterial biodegradable multi-block copolyester, characterized in that: Comprising, Antibacterial diol ester prepolymer and 2,5-furan dicarboxylic acid diol ester prepolymer are synthesized by ester exchange reaction of 2,5-furan dimethyl dicarboxylic acid DMFD, diol and antibacterial agent; Polytetramethylene ether glycol PTMEG is added into antibacterial diol ester prepolymer and 2,5-furan dicarboxylic acid diol ester prepolymer for polycondensation reaction to prepare antibacterial biodegradable multi-block copolyester; The antibacterial agent has the following structural formula: m = 1-21; The antibacterial agent is a highly heat-resistant antibacterial agent having a 5% thermal decomposition temperature T d ≥ 350°C; The content of the antibacterial agent in the multi-block copolyester is 0.01wt%-2wt% according to weight percentage; The structure of the diol is: R1 is selected from at least one residue after removing hydroxyl group in ethylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, 1,2-propanediol, neopentyl glycol, 1,4-cyclohexane dimethanol, 1,4-cyclohexanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, polyethylene glycol, polytetramethylene ether glycol, and polycaprolactone diol; The number average molecular weight of the PTMEG is between 250 and 6000.

2. The production method according to claim 1, characterized by: The antibacterial diol ester prepolymer has the following structural formula: R1 is selected from at least one residue after removing hydroxyl group in ethylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, 1,2-propanediol, neopentyl glycol, 1,4-cyclohexane dimethanol, 1,4-cyclohexanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, polyethylene glycol, polytetramethylene ether glycol, and polycaprolactone diol, and m = 1-21.

3. The production method according to claim 1, wherein: The 2,5-furan dicarboxylic acid diol ester prepolymer has the following structural formula: R1 is selected from at least one residue after removing hydroxyl group in ethylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3-propanediol, 1,2-propanediol, neopentyl glycol, 1,4-cyclohexane dimethanol, 1,4-cyclohexanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, polyethylene glycol, polytetramethylene ether glycol, and polycaprolactone diol.

4. The production method according to claim 1, wherein: The ester exchange reaction, wherein, a catalyst and a stabilizer are added, nitrogen is introduced during the reaction, the reaction temperature is 170-200℃, and methanol and water distilled out are removed during the reaction, and when the amount of methanol and water distilled out reaches more than 98% of the theoretical value, the reaction is ended at this stage; The catalyst is selected from at least one of titanium-based catalyst, antimony-based catalyst, germanium-based catalyst, tin-based catalyst, and zinc-based catalyst; The stabilizer is selected from at least one of ammonium dihydrogen phosphate, ammonium phosphite, diphenyl phosphite, triphenyl phosphite, diphenyl phosphate, triphenyl phosphate, dimethyl phosphate, trimethyl phosphate, ammonium phosphate, pyrophosphoric acid, hypophosphorous acid, phosphorous acid, and phosphoric acid.

5. The production method according to claim 1, wherein: The polycondensation reaction, wherein, a catalyst, a stabilizer, and a nucleating agent are added, The catalyst is at least one selected from titanium catalyst, antimony catalyst, germanium catalyst, tin catalyst, zinc catalyst; The stabilizer is at least one selected from ammonium dihydrogen phosphate, ammonium phosphite, diphenyl phosphite, triphenyl phosphite, diphenyl phosphate, triphenyl phosphate, dimethyl phosphate, trimethyl phosphate, ammonium phosphate, pyrophosphoric acid, hypophosphorous acid, phosphorous acid, phosphoric acid; The nucleating agent is at least one selected from fatty carboxylic acid metal compound, sorbitol benzylidene derivative, aromatic carboxylic acid metal compound, talc, calcium carbonate, silicon dioxide, alum, titanium dioxide, calcium oxide, magnesium oxide, carbon black, mica; The reaction temperature is 210-240 DEG C, the vacuum pump is opened and N2 is introduced, the flow rate of N2 is adjusted to make the internal pressure less than 100 Pa, and the reaction time is 1-8 h.

6. The application of the antibacterial biodegradable multi-block copolyester prepared by the preparation method in claims 1-5 in the fields of packaging and medical treatment.

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