Furandicarboxylic acid block copolyester and preparation method thereof

Abstract

The invention discloses furandicarboxylic acid block copolyester and a preparation method thereof, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: respectively carrying out dehydration and esterification reaction on furandicarboxylic acid, dihydric alcohol and a catalyst 1 as well as furandicarboxylic acid, 1, 4-cyclohexanedimethanol and a catalyst 2 under the protection of an inert atmosphere to respectively obtain an ester FEG01 of furandicarboxylic acid ethylene ester and an ester FCHM2 of furandicarboxylic acid and 1, 4-cyclohexanedimethanol; the preparation method comprises the following steps: uniformly mixing an ester FEG01 and an ester FCHM2 under the protection of an inert atmosphere, introducing a small amount of zirconium phosphate dispersion liquid, and respectively carrying out prepolymerization and final polycondensation reaction under certain vacuum and melting temperature to obtain the furandicarboxylic acid block copolyester. The furandicarboxylic acid block copolyester material obtained by the invention has higher crystallinity, higher barrier property and good transparency, and the preparation method is simple, easy to implement and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a furan dicarboxylic acid block copolyester and its preparation method. Background Technology

[0002] With the continuous depletion of petroleum resources, bio-based polymers, as an environmentally friendly plastic made from renewable resources, are increasingly being researched and developed using furanyl dicarboxylic acid as a monomer. These polymers have been used to replace or partially replace poly(ethylene furanyl dicarboxylate) resins obtained through the polymerization of terephthalic acid, and have replaced traditional non-renewable petroleum-based polymers such as polyethylene terephthalate (PET) resins, finding applications in fiber, medical, and packaging fields. However, bio-based polymers using furanyl dicarboxylic acid as a heterocyclic dicarboxylic acid and a rigid monomer suffer from processing defects due to their low mechanical properties, slow crystallization, and high melt viscosity, limiting their application range.

[0003] PEF has 10%–20% higher tensile strength and elastic modulus than PET resin, but its toughness is significantly lower, with an elongation at break of only 10%, far lower than PET's 100%–300%. In terms of crystallinity, PEF's crystallization rate and crystallinity are significantly lower than PET's. Specifically, PET's crystallization half-life is approximately 1–2 minutes, while PEF still requires more than 6 minutes to crystallize at 170°C. The crystallinity of pure PEF is typically below 10%, while PET can achieve 30%–40% crystallinity through conventional processing. Regarding melt viscosity, PEF's melt viscosity is more sensitive to temperature and shear rate. At 230℃, the melt viscosity of PEF is approximately 1000~1500 Pa·s, higher than that of PET (600~800 Pa·s), and its viscous flow activation energy is also higher (approximately 80 kJ / mol vs. 50 kJ / mol for PET). Therefore, PEF requires higher temperatures (260~280℃) and shear rates (>8000 s⁻¹) during extrusion. -1To achieve flowability comparable to PET, PEF (poly(ethylene glycol)) can only achieve similar properties, resulting in a narrower processing window. This is primarily due to the more pronounced hydrogen bonding effect between furanyl dicarboxylic acid and ethylene glycol. In terms of barrier properties, PEF significantly outperforms PET in gas barrier properties. Its oxygen permeability (0.01–0.03 cm³·μm / (m²·d·MPa)) is 10 times lower than PET, its carbon dioxide permeability (0.05–0.1 cm³·μm / (m²·d·MPa)) is 19 times lower, and its water vapor barrier properties (0.5–1.0 g·μm / (m²·d)) are 3–5 times lower (Avantium and Carlsberg's PEF beer bottle demonstrates a 5.2-fold increase in CO2 barrier properties (Nature Sustainability, 2020)). This advantage makes it a potential alternative to PET in the food packaging sector; for example, PEF beer bottles can extend shelf life by 2–3 times compared to PET.

[0004] In summary, further improvements are needed for PEF resin in the following aspects: 1) Optimization of crystallization performance: Low crystallization rate and crystallinity limit the application of PEF in fibers, films, and other fields. For example, PEF fibers have poor spinnability and are difficult to achieve high draw ratios, while PET fibers can achieve high strength and high orientation through conventional spinning processes. 2) Improvement of processability: High melt viscosity and narrow processing window increase the processing difficulty and energy consumption of PEF. For example, PEF injection molding requires raising the mold temperature to 80~100℃, while PET only requires 40~60℃. Currently, the main approach to improving the crystallization performance of PEF is to add inorganic nucleating agents, such as talc (2% mass fraction), which can shorten the isothermal crystallization peak time of PEF from 6 min to 1.8~4 min and increase the crystallinity to 13% (Xu Yutao et al. shortened the PEF crystallization peak time to 1.8~4 min through talc nucleation (Polymer Materials Science and Engineering, 2024)). Using multi-walled carbon nanotubes (2.5% mass fraction) can increase the crystallization rate of PEF by 35%, improve the crystallinity to 13%, and increase the thermal stability by 20°C. Using Surlyn® 8920 (1%–3% mass fraction), the half-crystallization time of PEF can be shortened to less than 2 minutes through the synergistic effect of heterogeneous nucleation and homogeneous nucleation (US20200056177A1).

[0005] In terms of copolymerization, polyethylene glycol is used for copolymerization. When 10% to 20% PEG is added, the melt viscosity of PEF can be reduced by 30% to 50%, improving processing fluidity and increasing toughness (elongation at break up to 55%). However, it also reduces its glass transition temperature and barrier properties. Smallbone et al. found that the melt viscosity of PEF is more sensitive to shear rate than that of PET (Macromolecules, 2018). Blending PEF with PBS resin can increase the impact strength of a 15% PBS blend from 2.5 kJ / m² to 15.5 kJ / m² and the tensile strength from 56.5 MPa to 73.0 MPa, but the resulting material is a milky white, opaque material, unsuitable for transparent films and parts. Using a PET / PEF (70 / 30) alloy, through the synergistic effect of chain extenders and plasticizers, the tensile strength reaches 65 MPa and the elongation at break increases to 55% (patent literature: CN 119661997 A, a patent by Keguosheng, improves the processing fluidity of PET / PEF alloys through chain extenders (2025), but also sacrifices the barrier properties of PEF).

[0006] Therefore, for high-performance bio-based PEF resins, while maintaining good barrier properties and mechanical strength, it is still necessary to improve their crystallinity, toughness, and processability in order to promote the commercial application of PEF in packaging, fibers, and other fields. Summary of the Invention

[0007] 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.

[0008] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0009] Therefore, the objective of this invention is to overcome the shortcomings of existing technologies in terms of crystallinity and processing performance, and to provide a furanyl dicarboxylic acid block copolyester. The structural formula of the furanyl dicarboxylic acid block copolyester is as follows: , Where x is an integer from 10 to 30, and y is an integer from 20 to 60.

[0010] Another objective of this invention is to overcome the shortcomings of existing technologies in terms of crystallization and processing performance, and to provide a method for preparing furan dicarboxylic acid block copolyester.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solutions, including: Furan dicarboxylic acid, ethylene glycol and catalyst 1 are mixed and heated and dehydrated under the protection of inert nitrogen gas to carry out a single esterification reaction to obtain esterified product FEG01. Furan dicarboxylic acid, 1,4-cyclohexanediethanol and catalyst 2 were mixed and gradually heated and dehydrated under an inert atmosphere to carry out a secondary esterification reaction to obtain esterified product FCHM2. Under an inert nitrogen atmosphere, esterified FEG01 and esterified FCHM2 were melt-mixed, and then nano-sheet zirconium phosphate dispersion was added. The mixture was heated to carry out a pre-condensation reaction, and then heated further to carry out a final condensation reaction to obtain furan dicarboxylic acid block copolyester.

[0012] In a preferred embodiment of the preparation method of furanyl dicarboxylic acid block copolyester of the present invention, the primary esterification reaction is wherein the molar ratio of furanyl dicarboxylic acid to ethylene glycol is 1:1.1~2.0; and the effective metal content of catalyst 1 is 100~300ppm.

[0013] In a preferred embodiment of the preparation method of furan dicarboxylic acid block copolyester of the present invention, the secondary esterification reaction is wherein the molar ratio of furan dicarboxylic acid to 1,4-cyclohexanediethanol is 1:1.1~2.0, and the effective metal content of catalyst 2 is 10~50ppm.

[0014] In a preferred embodiment of the preparation method of furan dicarboxylic acid block copolyester of the present invention, the catalyst 1 includes one or more of tin catalysts, germanium catalysts, and antimony catalysts, and the catalyst 2 includes a titanium catalyst or a mixture thereof with a tin catalyst. The tin-based catalysts include tin oxalate and dibutyltin oxide; the germanium-based catalysts include germanium dioxide; the antimony-based catalysts include antimony glycolate and antimony trioxide; and the titanium-based catalysts include tetrabutyl titanate.

[0015] In a preferred embodiment of the method for preparing the furanyl dicarboxylic acid block copolyester of the present invention, the primary esterification reaction and the secondary esterification reaction further include the addition of a heat stabilizer and / or an antioxidant to the reaction system. The heat stabilizer is used in a molar amount of 0.05-0.2% of the molar amount of furanyl dicarboxylic acid; the stabilizer includes one or more of phosphoric acid, phosphorous acid, triphenyl phosphate, and triphenyl phosphite. The molar amount of the antioxidant is 0 to 0.1% of the molar amount of furanyl dicarboxylic acid; the antioxidant includes one or more of antioxidant-1010, antioxidant-1076, and antioxidant-168.

[0016] In a preferred embodiment of the preparation method of furan dicarboxylic acid block copolyester of the present invention, the reaction temperature of the primary esterification reaction and the secondary esterification reaction is 170~230℃, and the reaction time is 1~5h.

[0017] In a preferred embodiment of the preparation method of the furan dicarboxylic acid block copolyester of the present invention, the inert atmosphere includes nitrogen.

[0018] As a preferred embodiment of the preparation method of furan dicarboxylic acid block copolyester of the present invention, wherein: the zirconium phosphate dispersion is a dispersion system obtained by forced dispersion of ethylene glycol as liquid phase and carboxylated polyether ethylene glycol as dispersant; Zirconium phosphate is a sheet-like nanosheet structure with a thickness of 30~100nm and a diameter of less than 1μm. The amount of zirconium phosphate added to the polymerization system is 0~0.3%.

[0019] As a preferred embodiment of the preparation method of furan dicarboxylic acid block copolyester of the present invention, the pre-condensation reaction is wherein the reaction pressure is ≤2000Pa, the reaction temperature is 230~250℃, and the reaction time is 0.5~1.5h.

[0020] In a preferred embodiment of the preparation method of the furanyl dicarboxylic acid block copolyester of the present invention, the final polycondensation reaction is carried out at a reaction pressure ≤200 Pa, a reaction temperature of 230~260℃, and a reaction time of 2~4 h. The viscosity of the melt and the final molecular weight of the resin are controlled by controlling the stirring current of the final polymerization reactor.

[0021] Beneficial effects of this invention: (1) The furanyl dicarboxylic acid copolyester prepared by this invention has improved crystallization ability compared with conventional homopolymerized polyethylene furanyl dicarboxylic acid resin, including increased crystallinity / enthalpy of crystallization and cold crystallization temperature Tc. It also has a significantly improved ability to block oxygen.

[0022] (2) The 2,5-furandicarboxylic acid and 1,4-cyclohexanediethanol block copolymer of the present invention has a bicyclic backbone that can impart excellent heat resistance to the copolyester, and can further improve the toughness, barrier properties and higher crystallinity of the copolymer. Its preparation method is simple, highly controllable and easy to implement, suitable for large-scale industrial production, and has broad application prospects in the medical and packaging fields.

[0023] (3) In this invention, after the esterification reaction, the temperature is raised and a vacuum is used for pre-condensation reaction. The molecular weight of the first intermediate product FEG01 increases during pre-condensation. When it undergoes block copolymerization with the second ester, the small molecule ethylene glycol monomer in the system can be gradually removed, reducing the by-products of the pre-condensation reaction and promoting the forward reaction. After the pre-condensation reaction, the temperature is raised and the pressure is reduced to carry out the condensation reaction, thereby obtaining a high molecular weight furan dicarboxylic acid block copolyester, ensuring the esterification rate and degree of polymerization. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying 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: Figure 1 These are the reaction equations for the esterification and polymerization processes.

[0025] Figure 2 The furan dicarboxylic acid copolyester of the present invention 1 H-NMR spectrum.

[0026] Figure 3 This is a typical DSC spectrum of furanyl dicarboxylic acid copolymer. Detailed Implementation

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0031] 1H NMR spectrum 1H-NMR was performed using a BRUKER AVIII 400 NMR spectrometer (400 MHz, CF3COOD). The test temperature was 25℃.

[0032] The molecular weight of copolyester is characterized by its intrinsic viscosity. The intrinsic viscosity test is as follows: the copolyester is vacuum dried at 70℃ for 12h, placed in 15 mL of phenol-tetrachloroethane (1:1) mixed solution, heated to dissolve, and its intrinsic viscosity is tested using an Ubbelohde viscometer in accordance with GB / T 3401-2007.

[0033] The crystallization characteristics of the copolymer were determined by thermal analysis using differential scanning calorimetry (Mettler-Toledo DSC) at a heating rate of 10 °C / min in a N2 atmosphere, with a temperature range of -50 °C to 280 °C.

[0034] The optical properties of the copolymer were determined according to the standard method ASTM D1003 "Standard Test Method for Transmittance and Haze of Transparent Plastics". The sample size was required to be ≥50×50 mm, and the original thickness was maintained. The surface was clean, free of bubbles and scratches. The ambient conditions were temperature 23±2℃ and relative humidity ≤50%. The instrument was an integrating sphere haze meter with a xenon lamp or D65 standard light source and a spectral range of 380~780 nm.

[0035] The oxygen barrier properties of the copolymer were tested using the pressure difference method to measure the oxygen concentration on both sides of the film and calculate the permeation rate by pressure change, in accordance with GB / T 1038-2000 "Test Method for Gas Permeability of Plastic Films and Sheets - Pressure Difference Method"; the test conditions were as follows: temperature: 23℃, humidity: 50% RH, sample preparation: the film sample should be cut into a circle with a diameter ≥ 50mm, with no wrinkles or scratches on the surface, and equilibrated in a standard environment for 24 hours before the test.

[0036] The configuration of the embodiments of the present invention is shown in Table 1: Table 1

[0037] Example 1

[0038] This embodiment provides a method for preparing furan dicarboxylic acid copolyester, wherein the esterification and polymerization processes can be as follows: Figure 1 The reaction equation shown is given, where x and y are both integers between 10 and 60, specifically: 1) 3325g of 2,5-furandicarboxylic acid and 1586g of ethylene glycol (EG) were added to a reaction vessel. Then, germanium dioxide catalyst (germanium content of 100ppm of total monomer content) and antimony glycol catalyst (antimony content of 150ppm) were added, along with 0.1% triphenyl phosphate and 0.1% antioxidant 1010. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3h. Dehydration was carried out to achieve an esterification rate of >92%, yielding the intermediate esterification product FEG01. 2) Add 175g of 2,5-furandicarboxylic acid (FDCA) and 193.8g of 1,4-cyclohexanediethanol (CHDM) to a reactor, then add tetrabutyl titanate catalyst (with an effective titanium content of 15ppm of the total monomer content), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010. Stir well under a nitrogen atmosphere, raise the temperature to 230℃ and react for 3 hours until the esterification rate is greater than 92% and near the limit of water effluent to obtain the intermediate esterification product. Repeat several times to obtain approximately 7500g of FCHM2 esterification product, which is then packaged under nitrogen protection for later use.

[0039] 3) Under nitrogen protection, 331g of esterified FCHM2 was added to a reactor containing FEG01 esterified melt, and a zirconium phosphate-ethylene glycol dispersion with an effective zirconium phosphate content of 0.1% was further added. The mixture was thoroughly mixed, and the temperature was gradually increased to 230℃. The pressure was gradually evacuated to 2000Pa, and the pre-condensation reaction was carried out for 45min. Then the temperature was further increased to 255℃, and the pressure was gradually reduced to below 50Pa. The polycondensation reaction was carried out for 3h to obtain furan 1750 formic acid block copolyester.

[0040] See Figure 2 The NMR spectra show that CHDM was successfully incorporated into the polymer backbone of the copolymer. For the furanyl dicarboxylic acid-CHDM copolymer, CH2 in the furan ring and CH2 in the EG unit are represented by the characteristic signals of CH2 (b) in CHDM, which appear at 4.07 ppm and 4.09 ppm, respectively, while multiple peaks of CH (c) and methylene (d) appear at 1.63 ppm, 1.74 ppm and 0.96 ppm, respectively.

[0041] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.66.

[0042] Example 2

[0043] 1) 3150g of 2,5-furandicarboxylic acid and 1502g of ethylene glycol were added to a reaction vessel, along with germanium dioxide catalyst (germanium content of 100ppm of total monomer content), antimony glycol catalyst (antimony content of 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3 hours. Dehydration was carried out to achieve an esterification rate of >92%, yielding the first intermediate esterification product FEG01. 2) Using the method of Example 1, 350g of 2,5-furandicarboxylic acid (FDCA) and 387.7g of 1,4-cyclohexanediethanol (CHDM) were used to synthesize the esterified product FCHM2.

[0044] 3) Add 664g of FCHM2 esterification product to the polymerization reactor, and add 0.1% effective content of zirconium phosphate-ethylene glycol dispersion, mix thoroughly with FEG01, gradually raise the temperature to 230℃, gradually evacuate to a pressure of 2000Pa, and perform pre-condensation reaction for 45min; then raise the temperature further to 255℃, gradually reduce the pressure to below 50Pa, and perform condensation reaction for 3h, controlling the stirring current value to obtain furan dicarboxylic acid block copolyester.

[0045] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.67.

[0046] Example 3

[0047] 1) 2800g of 2,5-furandicarboxylic acid and 1335g of ethylene glycol were added to a reaction vessel, along with germanium dioxide catalyst (germanium content of 100ppm of total monomer content), ethylene glycol antimony catalyst (antimony content of 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3 hours to obtain the first intermediate product FEG01. 2) Using the method of Example 1, 700g of 2,5-furandicarboxylic acid (FDCA) and 775.4g of 1,4-cyclohexanediethanol (CHDM) were used to synthesize the esterified product FCHM2.

[0048] 3) Under nitrogen protection, 1327g of the FCHM2 esterification product was added to the reactor, along with 0.1% effective content of zirconium phosphate-ethylene glycol dispersion, and thoroughly mixed with the first esterification product FEG01. The temperature was gradually increased to 230℃, and the pressure was gradually evacuated to 2000Pa. The pre-condensation reaction was carried out for 45min. Then, the temperature was further increased to 255℃, and the pressure was gradually reduced to below 50Pa. The condensation reaction was carried out for 3h, and the stirring current was controlled to obtain furan dicarboxylic acid block copolyester.

[0049] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.66.

[0050] Example 4

[0051] 1) 2450g of 2,5-furandicarboxylic acid and 1168g of ethylene glycol were added to a reaction vessel, along with germanium dioxide catalyst (germanium content of 100ppm of total monomer content), ethylene glycol antimony catalyst (antimony content of 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3 hours to obtain the first intermediate product FEG01. 2) Using the method of Example 1, 1050g of 2,5-furandicarboxylic acid (FDCA) and 1163.1g of 1,4-cyclohexanediethanol (CHDM) were used to synthesize the esterified product FCHM2.

[0052] 3) Under nitrogen protection, 1990g of the FCHM2 esterification product was added to the reactor, along with 0.1% effective zirconium phosphate-ethylene glycol dispersion, and thoroughly mixed with the esterification product FEG01. The temperature was gradually increased to 230℃, and the pressure was gradually evacuated to 2000Pa. The pre-condensation reaction was carried out for 45min. Then, the temperature was further increased to 255℃, and the pressure was gradually reduced to below 50Pa. The condensation reaction was carried out for about 3h, and the stirring current was controlled to obtain furan dicarboxylic acid block copolyester.

[0053] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.63.

[0054] Example 5

[0055] 1) 3150g of 2,5-furandicarboxylic acid and 1502g of ethylene glycol were added to a reaction vessel, along with germanium dioxide catalyst (germanium content of 100ppm of total monomer content), ethylene glycol antimony catalyst (antimony content of 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3 hours to obtain the first intermediate product FEG01. 2) Using the method of Example 1, 372g of 2,5-furandicarboxylic acid (FDCA) and 388g of 1,4-cyclohexanediethanol (CHDM) were used to synthesize the esterified product FCHM2.

[0056] 3) 682g of the FCHM2 esterification product from Example 1 was added to a reactor, along with a zirconium phosphate-ethylene glycol dispersion with an effective content of 0.2%, and thoroughly mixed with the esterification product FEG01. The temperature was gradually increased to 230°C, and the pressure was gradually evacuated to 2000Pa. The pre-condensation reaction was carried out for 45 minutes. Then, the temperature was further increased to 255°C, and the pressure was gradually reduced to below 50Pa. The condensation reaction was carried out for 3 hours, and the stirring current was controlled to obtain furan dicarboxylic acid block copolyester.

[0057] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.66.

[0058] The comparative examples of this invention are shown in Table 2.

[0059] Table 2

[0060] Comparative Example 1

[0061] 1) 3500g of 2,5-furandicarboxylic acid and 1669g of ethylene glycol were added to a reaction vessel, along with germanium dioxide catalyst (germanium content of 100 ppm of total monomer content), ethylene glycol antimony catalyst (antimony content of 150 ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3 hours. Dehydration was carried out until the esterification rate was greater than 92%, yielding the first intermediate product FEG01. 2) Gradually raise the temperature of the esterification product FEG01 to 230℃, gradually evacuate to a pressure of 2000Pa, and perform a pre-condensation reaction for 45 minutes; then further raise the temperature to 245℃, gradually reduce the pressure to below 50Pa, and perform a condensation reaction for 3 hours, controlling the stirring current value to obtain pure ethylene glycol furanate.

[0062] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was found to be 0.68.

[0063] Comparative Example 2

[0064] This comparative example uses homogeneous polymerization of 10% mol CHDM and FDCA, specifically: 1) 3500g of 2,5-furandicarboxylic acid, 1530g of ethylene glycol, and 323g of CHDM monomer were added to a reaction vessel. Then, germanium dioxide catalyst (germanium content was 100ppm of the total monomer content), ethylene glycol antimony catalyst (antimony content was 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010 were added. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3 hours. Dehydration was carried out until the esterification rate was greater than 92%, and an esterification product FEG-CHM was obtained. 2) Under nitrogen protection, 0.1% zirconium phosphate-ethylene glycol dispersion of the total monomer amount was added, and the temperature of the esterification product FEG-CHM was gradually raised to 230°C. The vacuum was gradually evacuated to a pressure of 2000 Pa, and the pre-condensation reaction was carried out for 45 min. Then the temperature was further raised to 255°C, the pressure was gradually reduced to below 50 Pa, and the condensation reaction was carried out for 3 h. The stirring current was controlled to obtain ethylene glycol furanate-CHDM copolyester.

[0065] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.66.

[0066] Comparative Example 3

[0067] This comparative example uses an excess of plate-like catalyst system, specifically: 1) 3150g of 2,5-furandicarboxylic acid and 1502g of ethylene glycol were added to a reaction vessel, along with germanium dioxide catalyst (germanium content of 100ppm of total monomer content), ethylene glycol antimony catalyst (antimony content of 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 210℃ for 3 hours. Dehydration was carried out until the esterification rate was greater than 92%, yielding an esterification product FEG01. 2) Using the method of Example 1, 372g of 2,5-furandicarboxylic acid (FDCA) and 388g of 1,4-cyclohexanediethanol (CHDM) were used to synthesize the esterified product FCHM2.

[0068] 3) Add 684g of FCHM2 esterification product to the reactor, and add 0.4% effective content of zirconium phosphate-ethylene glycol dispersion, mix thoroughly with esterification product FEG01, gradually raise the temperature to 230℃, gradually evacuate to a pressure of 2000Pa, and perform pre-condensation reaction for 45min; then raise the temperature further to 255℃, gradually reduce the pressure to below 50Pa, and perform condensation reaction for 3h, controlling the stirring current value to obtain furan dicarboxylic acid block copolyester.

[0069] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.66.

[0070] Comparative Example 4

[0071] This comparative example does not use a sheet-like catalyst system; specifically: 1) 3150g of 2,5-furandicarboxylic acid and 1502g of ethylene glycol were added to a reaction vessel, along with germanium dioxide catalyst (germanium content of 100ppm of total monomer content), ethylene glycol antimony catalyst (antimony content of 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 210℃ for 3 hours. Dehydration was carried out until the esterification rate was greater than 92%, yielding an esterification product FEG01. 2) Using the method of Example 1, 372g of 2,5-furandicarboxylic acid (FDCA) and 388g of 1,4-cyclohexanediethanol (CHDM) were used to synthesize the esterified product FCHM2.

[0072] 3) 684g of FCHM2 esterification product was added to the reactor under nitrogen protection and thoroughly mixed with esterification product FEG01. The temperature was gradually increased to 230℃ and the vacuum was gradually evacuated to a pressure of 2000Pa. The pre-condensation reaction was carried out for 45min. Then the temperature was further increased to 255℃ and the pressure was gradually reduced to below 50Pa. The condensation reaction was carried out for 3h. The stirring current was controlled to obtain furan dicarboxylic acid block copolyester.

[0073] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.66.

[0074] Comparative Example 5

[0075] This comparative example uses a one-pot cooking process, specifically: 1) 3500g of 2,5-furandicarboxylic acid, 1530g of ethylene glycol, and 323g of CHDM monomer were added to a reaction vessel. Then, germanium dioxide catalyst (germanium content was 100ppm of the total monomer content), ethylene glycol antimony catalyst (antimony content was 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010 were added. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3 hours. Dehydration was carried out until the esterification rate was greater than 92%, and an esterification product FEG-CHM was obtained. 2) Under nitrogen protection, the temperature of the esterification product FEG-CHM was gradually increased to 230℃, and the vacuum was gradually evacuated to a pressure of 2000Pa. The pre-condensation reaction was carried out for 45 minutes. Then the temperature was further increased to 255℃, and the pressure was gradually reduced to below 50Pa. The condensation reaction was carried out for 3 hours. The stirring current was controlled to obtain ethylene glycol furanate-CHDM copolyester.

[0076] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.66.

[0077] Comparative Example 6

[0078] 1) Using the method of Example 1, 3500g of 2,5-furandicarboxylic acid (FDCA) and 3644g of 1,4-cyclohexanediethanol (CHDM) were used to synthesize the esterified product FCHM2.

[0079] 2) Under nitrogen protection, 6500g of the FCHM2 esterification product was added to a reactor. The temperature was gradually increased to 230℃, and the pressure was gradually evacuated to 2000Pa for pre-polymerization reaction for 45 minutes. Then, the temperature was further increased to 255℃, and the pressure was gradually reduced to below 50Pa for polycondensation reaction for about 4 hours. The stirring current was controlled to obtain poly(1,4-cyclohexanediethanol) furanyl dicarboxylic acid. Experiments showed that the viscosity increased slowly in the final polymerization stage, and the stirring current could not reach the target value.

[0080] The characteristic viscosity of the polyester in this example was measured to be 0.55. This comparative example uses a pure CHDM and FDCA polymer, which cannot achieve a significantly higher molecular weight.

[0081] Comparative Example 7

[0082] This comparative example is set with reference to patent CN119505201A, specifically as follows: 1) 3500g of 2,5-furandicarboxylic acid, 1201g of ethylene glycol, 323g of CHDM monomer, and 264g of 1,6-hexanediol monomer were added to a 30L reactor. Then, germanium dioxide catalyst (germanium content of 100ppm of total monomer content), ethylene glycol antimony catalyst (antimony content of 150ppm), 0.1% triphenyl phosphate, and 0.1% antioxidant 1010 were added. Under a nitrogen atmosphere, stirring was started, and the temperature was raised to 220℃ for 3 hours. Dehydration was carried out until the esterification rate was greater than 92%, and an esterification product FEG-CHM-HOL (poly(ethylene glycol-CHDM-butanediol copolymer)) was obtained. 2) Under nitrogen protection, the temperature of the esterification product FEG-CHM-HOL was gradually increased to 230℃, and the vacuum was gradually evacuated to a pressure of 2000Pa. The pre-condensation reaction was carried out for 45 minutes. Then, the temperature was further increased to 255℃, and the pressure was gradually reduced to below 50Pa. The condensation reaction was carried out for 3 hours. The stirring current was controlled to obtain ethylene glycol furanate-CHDM-hexanediol copolyester.

[0083] The characteristic viscosity of the furanyl dicarboxylic acid block copolyester in this embodiment was measured to be 0.66.

[0084] The polyfuran dicarboxylic acid polyester material obtained using the above process and formulation has the following crystallization characteristics, transparency, and oxygen barrier properties, as shown in Table 3.

[0085] Table 3 Comparison of properties of furanyl dicarboxylic acid-CHDM copolymer illustrate Characteristic viscosity Enthalpy of crystallization, J / g, of which the enthalpy of crystallization of 100% is 93.6 J / g. Crystallinity, % Tc, ℃ transparency,% Haze, % <![CDATA[Barrier property / O2, cm³·μm / (m²·d·MPa)]]> Example 1 5% CHDM, NP 0.1% 0.66 20 21.4 156 85 9 0.02 Example 2 10% CHDM, NP 0.1% 0.67 36 35.3 186 85 9 0.016 Example 3 20% CHDM, NP 0.1% 0.66 42 41.7 192 85 9 0.013 Example 4 30% CHDM, NP 0.1% 0.63 45 43.8 190 85 9 0.012 Example 5 10% CHDM, NP 0.2% 0.66 47 47.0 199 85 13 0.01 Comparative Example 1 Pure PEF 0.68 28 26.7 162 88 2.8 0.022 Comparative Example 2 Homopolymer 10% CHDM, NP0.1% 0.66 10 10.7 154 85 9 0.024 Comparative Example 3 10% CHDM, NP 0.4% 0.66 43 42.7 190 70 20 0.06 Comparative Example 4 10% CHDM, NP 0% 0.66 30 29.9 177 88 2.8 0.022 Comparative Example 5 Homopolymer 10% CHDM, NP0% 0.66 Unpredictable 0.0 Unpredictable 88 2.8 0.023 Comparative Example 6 FDCA-CHDM,NP0% 0.55 30 37.4 190 90 2 Unable to form a film Comparative Example 7 0.67 32.5 34.7 185 89 2 0.024

[0086] Table 2 combined with Figure 2 , 3 As can be seen, when the CHDM block structure is introduced at a molar ratio greater than 5%, Examples 1 to 5 generally show improved oxygen barrier properties compared to pure polyfurandicarboxylic acid polyester materials, with the permeability decreasing from a typical 0.022 cm³·μm / (m²·d·MPa) to around 0.013 cm³·μm / (m²·d·MPa). In particular, the introduction of trace amounts of nano-sheet zirconium phosphate components can further enhance the resin's oxygen barrier properties. However, excessive nano-components may lead to certain defects in the film's performance, thereby compromising the material's transparency and barrier properties. Simultaneously, the introduction of the block-structured CHDM copolymer can significantly improve the resin's crystallinity, possibly because the furandicarboxylic acid-CHDM block segments generally have better regularity and can act as preferential crystallizers in the copolymer. Furthermore, the heterogeneous nucleation of nano-zirconium phosphate components can further improve the crystallization efficiency of the copolymer material.

[0087] This invention utilizes a multi-stage esterification, prepolymerization, and final polymerization process on a flexible modified polyester polymerization production line to obtain a furan dicarboxylic acid copolyester resin with a block structure. This process can efficiently produce copolyester material chips with high transparency, enhanced barrier properties, and crystallinity.

[0088] This invention innovatively modifies the conventional structure of polyester by using diol monomers as the main component, adding 1,4-cyclohexanediethanol as a modified diol, and adding zirconium phosphate with a nanosheet structure as a crystal nucleating and barrier reinforcing agent. Polymerization is then carried out in the diacid monomer component of furanyl dicarboxylic acid (FDCA) to obtain a block-structured copolyester resin with enhanced crystallinity and barrier properties. The introduction of 1,4-cyclohexane into the block primarily improves the barrier and thermal stability properties of the copolyester, and also improves its crystallinity. The sheet-like nano-zirconium phosphate can act as a heterogeneous nucleating component and barrier reinforcing agent, improving the crystallinity and barrier efficiency of the copolymer. However, excessive addition of inorganic nanocomponents can also reduce the transparency and haze of the copolyester.

[0089] Comparative Example 7, which uses a hexanediol toughening system and references the technical solution of patent CN119505201A, also achieves the effects of enhanced crystallinity and increased viscosity. However, the formulation system uses more long-chain polyols, which makes polymerization control more complex. Long-chain polyols are prone to chain breakage at high temperatures, causing the material color to tend to turn yellow.

[0090] In actual production, two independent esterification reactors are used to carry out the esterification reaction to obtain esterification products with different properties. The esterified products then enter a short-process prepolymerization and final polymerization step to obtain copolyester chips with enhanced crystallinity, barrier properties, and maintained high transparency.

[0091] This invention involves dehydrating furanyl dicarboxylic acid, a diol, and catalyst 1, and furanyl dicarboxylic acid, 1,4-cyclohexanediethanol, and catalyst 2 under an inert nitrogen atmosphere, followed by esterification reactions to obtain esterified furanyl dicarboxylic acid ethylene glycol 1 (FEG01) and esterified furanyl dicarboxylic acid and 1,4-cyclohexanediethanol FCHM2. Under an inert atmosphere, the FEG01 and FCHM2 esters are mixed uniformly, and a small amount of zirconium phosphate dispersion is introduced. Prepolymerization and final polycondensation reactions are then carried out under specific vacuum and melting temperatures to obtain a furanyl dicarboxylic acid block copolyester. The furanyl dicarboxylic acid block copolyester material obtained by this invention possesses high crystallinity, superior barrier properties, and good transparency. Furthermore, the preparation method is simple, easy to implement, and suitable for large-scale industrial production.

[0092] 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 claims of the present invention.

Claims

1. A furanyl dicarboxylic acid block copolyester, characterized in that: The structural formula of the furan dicarboxylic acid block copolyester is: ， Where x is an integer from 10 to 30, and y is an integer from 20 to 60.

2. A method for preparing furanyl dicarboxylic acid block copolyester as described in claim 1, characterized in that: include, Furan dicarboxylic acid and ethylene glycol undergo a single esterification reaction under the action of catalyst 1 and in an inert atmosphere to obtain the esterified compound FEG01. Furan dicarboxylic acid and 1,4-cyclohexanediethanol undergo a secondary esterification reaction under the action of catalyst 2 and in an inert atmosphere to obtain the esterified compound FCHM2. Under an inert atmosphere, esterified FEG01 and esterified FCHM2 were melt-mixed and then added to a zirconium phosphate dispersion. The mixture was heated to carry out a pre-condensation reaction, and then heated further to carry out a final condensation reaction to obtain a furan dicarboxylic acid block copolyester. The amount of zirconium phosphate added to the polymerization system is 0.1~0.3 wt.%.

3. The method for preparing furanyl dicarboxylic acid block copolyester as described in claim 2, characterized in that: In the primary esterification reaction, the molar ratio of furanyl dicarboxylic acid to ethylene glycol is 1:1.1~2.0; and the effective metal content of catalyst 1 is 100~300 ppm.

4. The method for preparing furanyl dicarboxylic acid block copolyester as described in claim 2, characterized in that: In the secondary esterification reaction, the molar ratio of furanyl dicarboxylic acid and 1,4-cyclohexanediethanol is 1:1.1~2.0, and the effective metal content of catalyst 2 is 10~50 ppm.

5. The method for preparing furanyl dicarboxylic acid block copolyester as described in claim 2, 3, or 4, characterized in that: The catalyst 1 includes one or more of tin-based catalysts, germanium-based catalysts, and antimony-based catalysts, and the catalyst 2 includes a titanium-based catalyst or a mixture thereof with a tin-based catalyst. The tin-based catalysts include tin oxalate and dibutyltin oxide; the germanium-based catalysts include germanium dioxide; the antimony-based catalysts include antimony glycolate and antimony trioxide; and the titanium-based catalysts include tetrabutyl titanate.

6. The method for preparing furanyl dicarboxylic acid block copolyester as described in claim 2, characterized in that: The primary and secondary esterification reactions further include the addition of heat stabilizers and / or antioxidants to the reaction system. The heat stabilizer is used in a molar amount of 0.05-0.1% of the molar amount of furanyl bisaccharide; the heat stabilizer is a phosphorus-containing ester, including one or more of triphenyl phosphate and triphenyl phosphate. The molar amount of the antioxidant is 0.01 to 0.1% of the molar amount of furanyl dicarboxylic acid; the antioxidant includes one or more of antioxidant 1010, antioxidant 1076, and antioxidant 1098.

7. The method for preparing furanyl dicarboxylic acid block copolyester as described in claim 6, characterized in that: The primary and secondary esterification reactions are carried out at temperatures of 170-230°C for 1-5 hours.

8. The method for preparing furanyl dicarboxylic acid block copolyester as described in claim 2, characterized in that: The zirconium phosphate dispersion is a dispersion system obtained by forced liquid-phase dispersion using ethylene glycol as the liquid phase and carboxylated polyether ethylene glycol as the dispersant. Zirconium phosphate is a nanosheet structure with a thickness of 30-100 nm and a diameter of less than 1 μm.

9. The method for preparing furanyl dicarboxylic acid block copolyester as described in claim 2, characterized in that: The pre-condensation reaction is wherein the reaction pressure is ≤2000Pa, the reaction temperature is 230~250℃, and the reaction time is 0.5~1.5h.

10. The method for preparing furanyl dicarboxylic acid block copolyester as described in claim 2, characterized in that: The final polycondensation reaction is carried out under the following conditions: reaction pressure ≤ 200 Pa, reaction temperature 230~260℃, and reaction time 2~4 h.

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