A highly crystalline furan-based polyester, its preparation method and application

Abstract

This invention provides a highly crystalline furan-based polyester, its preparation method, and its applications. The highly crystalline furan-based polyester is prepared in the presence of a crystallization improver; the crystallization improver is at least one of cyclic monohydroxy acetal compounds. The preparation method includes reacting components, including furan dicarboxylic acid or its derivatives, and diols, in the presence of the crystallization improver to prepare the highly crystalline furan-based polyester. By introducing a crystallization improver into the reaction system for generating furan-based polyester, this invention significantly inhibits the etherification side reaction, reduces the content of etherification byproducts in the furan-based polyester product, and results in better color value and transparency, significantly improving the crystallinity of the furan-based polyester.

Description

Technical Field

[0001] This invention relates to the field of polyesters, and more specifically, to a highly crystalline furan-based polyester, its preparation method, and its applications. Background Technology

[0002] Compared to PET polyester, furan-based polyesters (such as PEF polyester) have higher modulus, glass transition temperature, and tensile strength, as well as excellent barrier properties. Furthermore, the monomer 2,5-furandicarboxylic acid is derived from renewable plant-based resources, making it a promising alternative to petroleum-based terephthalic acid. PEF polyester has broad application prospects in fibers, films, and bottles.

[0003] Crystallization performance is an important indicator of furan-based polyesters, affecting their processing and physical properties. Due to the high rigidity and polarity of the molecular chain, chain end movement is difficult, resulting in a slow crystallization rate in PEF polyesters, which affects the processing performance of furan-based polyesters.

[0004] Currently, the main method to improve the crystallization properties of furan-based polyesters is to add nucleating agents to the polymer matrix. However, inorganic nucleating agents have poor compatibility with the polymer matrix, are prone to agglomeration, and affect the physical properties and transparency of the polymer.

[0005] Chinese patent CN107118521A discloses a poly(ethylene furanate) resin composition that significantly improves the crystallization rate and relative crystallinity of poly(ethylene furanate) by adding a nucleating agent. The nucleating agent is one or more of talc, sodium carbonate, silica, isosorbide, sodium benzoate, N,N'-ethylene bislauramide, and ionic polymers of ethylene-methacrylic acid.

[0006] Chinese patent CN108047492A discloses a method for preparing rapidly crystallizing polyethylene 2,5-furandicarboxylate plastic. The method involves premixing isooctyl 2,5-furandicarboxylate and polyethylene 2,5-furandicarboxylate in a specific mass percentage, followed by melt-blending and extrusion into strands using a twin-screw extruder. However, isooctyl 2,5-furandicarboxylate, as an organic small molecule nucleating agent, poses a risk of precipitation.

[0007] Therefore, it is necessary to study a highly crystalline furan-based polyester that can significantly improve its crystallinity without adding nucleating agents, without affecting polymerization activity, and also provide some improvements in color value and transparency, thereby improving the processing and physical properties of furan-based polyester and having a wider range of application prospects. Summary of the Invention

[0008] To address the technical problems existing in the prior art, this invention provides a highly crystalline furan-based polyester, its preparation method, and its application.

[0009] This invention improves the crystallization properties of PEF polyester materials by adding an appropriate amount of crystallization improver to the reaction system. On the one hand, the crystallization improver is a reactive organic molecule that mainly exists at the polymer chain end and acts as a macromolecular nucleating agent, thereby improving the crystallization properties of PEF polyester materials and avoiding the problem of nucleating agent precipitation. On the other hand, the addition of the crystallization improver effectively improves the color value of furan-based polyester products while also providing good transparency.

[0010] By introducing a crystallization modifier into the reaction system for generating furan-based polyesters, this invention significantly inhibits the etherification side reaction, reduces the content of etherification byproducts in furan-based polyester products, and results in better color value and transparency, thereby significantly improving the crystallization performance of furan-based polyesters.

[0011] One objective of this invention is to provide a highly crystalline furan-based polyester, which is prepared in the presence of a crystallinity improver; the crystallinity improver is at least one of cyclic monohydroxy acetal compounds.

[0012] The cyclic monohydroxy acetal compound used in this invention has a higher electron cloud density of monohydroxy acetal than that of ethylene glycol during the esterification or transesterification stage of the PEF polyester reaction. This causes it to compete with ethylene glycol for dehydration and etherification, resulting in a decrease in diethylene glycol production. Only a small amount of molecular chain end ether is produced, and the end ether acts as a nucleating agent.

[0013] In a preferred embodiment of the present invention,

[0014] The crystallization improver is at least one of 1,3-dioxane-2-methanol (CAS: 5694-68-8), (4-methyl-1,3-dioxane-2-yl)methanol (CAS: 112474-18-7), (1,3-dioxane-2-yl)methanol (CAS: 39239-93-5), 2-(1,3-dioxane-2-yl)ethanol (CAS: 5465-07-6), and 1,3-dioxane-2-propane-1-ol (CAS: 85391-14-6); and / or,

[0015] The highly crystalline furan-based polyester is obtained by reacting components including furan diacid or its derivatives and diols in the presence of a crystallization improver; preferably, the furan diacid or its derivatives are at least one of furan dicarboxylic acid and dimethyl furan dicarboxylate; and / or, the diol is at least one of alkylene glycols, preferably at least one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, 1,4-cyclohexanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

[0016] In a preferred embodiment of the present invention,

[0017] The intrinsic viscosity of the highly crystalline furan-based polyester is greater than 0.6 dl / g; and / or,

[0018] The highly crystalline furan-based polyester exhibits an isothermal semi-crystallization time of ≤10 min at 165°C; and / or,

[0019] The visible light transmittance of the highly crystalline furan-based polyester is above 90%.

[0020] A second objective of this invention is to provide a method for preparing highly crystalline furan-based polyesters, comprising the following steps:

[0021] The highly crystalline furan-based polyester is prepared by reacting components including furan dicarboxylic acid or its derivatives and diols in the presence of a crystallization improver.

[0022] The resulting highly crystalline furan-based polyester has a low diethylene glycol content.

[0023] In a preferred embodiment of the present invention,

[0024] The molar ratio of the furan diacid or its derivative to the diol is 1:(1.05–2.5); preferably 1:(1.3–2.1); and / or,

[0025] The amount of the crystallization improver is 0.05 to 10‰ of the weight of the generated highly crystalline furan-based polyester, preferably 0.1 to 3‰.

[0026] Because of the excess of diol, this invention uses the theoretically generated weight of highly crystalline furan-based polyester as the basis when metering the crystallization improver and catalyst. The weight of the theoretically generated highly crystalline furan-based polyester is calculated by taking the molar amount of furan diacid or its derivative as the molar amount of the repeating unit of the generated highly crystalline furan-based polyester. For example, if 3 mol of furan diacid is used and reacts with ethylene glycol, the molar mass of the repeating unit of the generated polyethylene furanate dicarboxylate is 182 g / mol, and the mass of 3 mol is 546 g. Therefore, the theoretically generated highly crystalline furan-based polyester weight... The amount is 546g; the amount of dimethyl furanate is 3mol, which reacts with ethylene glycol to produce a repeating unit of polyethylene furanate with a molar mass of 182g / mol, and the mass of 3mol is 546g. Therefore, the theoretical weight of the highly crystalline furan-based polyester produced is 546g; the amount of furanate is 3mol, which reacts with 1,3-propanediol to produce a repeating unit of propylene furanate with a molar mass of 196g / mol, and the mass of 3mol is 588g. Therefore, the theoretical weight of the highly crystalline furan-based polyester produced is 588g.

[0027] In a preferred embodiment of the present invention,

[0028] The reaction is carried out in the presence of a catalyst, preferably at least one of antimony-based catalysts, titanium-based catalysts, and other metal-based catalysts, more preferably at least one of antimony-based catalysts and titanium-based catalysts; even more preferably, the antimony-based catalyst is at least one of antimony glycolate, antimony acetate, and antimony trioxide; the titanium-based catalyst is at least one of tetraisopropyl titanate and tetrabutyl titanate; and the other metal-based catalyst is at least one of zinc acetate, zinc oxide, and germanium oxide.

[0029] In a preferred embodiment of the present invention,

[0030] The amount of catalyst used is determined based on the amount of active metal in the catalyst:

[0031] When an antimony-based catalyst is added, the weight of antimony atoms in the catalyst is 50–500 ppm of the weight of the generated highly crystalline furanyl polyester; preferably 200–250 ppm; and / or,

[0032] When a titanium-based catalyst is added, the weight of titanium atoms in the catalyst is 2 to 20 ppm of the weight of the generated highly crystalline furanyl polyester; preferably 5 to 10 ppm; and / or,

[0033] When other metal catalysts are added, the weight of the metal atoms in the other metal catalysts is 2 to 500 ppm of the weight of the generated highly crystalline furanyl polyester; preferably 5 to 300 ppm.

[0034] In a preferred embodiment of the present invention,

[0035] The reaction involves first performing an esterification reaction to obtain an esterified product, followed by a polycondensation reaction to obtain the highly crystalline furan-based polyester; preferably,

[0036] The esterification reaction conditions are: reaction temperature of 135–240°C, reaction pressure of 0–0.35 MPa (gauge pressure), and reaction time of 90–130 min; preferably: reaction temperature of 150–240°C, reaction pressure of 0–0.28 MPa (gauge pressure), and reaction time of 100–120 min; and / or,

[0037] The conditions for the polycondensation reaction are: reaction temperature of 230-270℃, reaction pressure of 0-0.5 MPa (absolute pressure), and reaction time of 60-180 min; preferably: reaction temperature of 235-265℃, reaction pressure of 0-150 Pa (absolute pressure), and reaction time of 100-150 min.

[0038] The third objective of this invention is to provide a highly crystalline furan-based polyester obtained by the above preparation method;

[0039] Preferably,

[0040] The intrinsic viscosity of the highly crystalline furan-based polyester is greater than 0.6 dl / g; and / or,

[0041] The highly crystalline furan-based polyester exhibits an isothermal semi-crystallization time of ≤10 min at 165°C; and / or,

[0042] The visible light transmittance of the highly crystalline furan-based polyester is above 90%.

[0043] The fourth objective of this invention is to provide an application of highly crystalline furan-based polyester in resin products, preferably in resin fibers, resin films, and resin bottles.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] This invention introduces a crystallization modifier into the reaction system for generating furan-based polyesters. This modifier can directly react to the chain ends of the polymer without affecting the polymerization activity. The crystallization modifier significantly inhibits the etherification side reaction, reduces the content of etherification by-products in furan-based polyester products, and has better color value and transparency, thus significantly improving the crystallization performance of furan-based polyesters.

[0046] The cyclic monohydroxy acetal compound used in this invention reacts with diols during the esterification or transesterification stage of the PEF polyester reaction. Taking ethylene glycol as an example, the electron cloud density of the monohydroxyl group in the cyclic monohydroxy acetal compound is greater than that of the hydroxyl group in ethylene glycol. This causes it to compete with ethylene glycol for dehydration and etherification, resulting in a reduced diethylene glycol production and only a small amount of terminal ethers being generated. These terminal ethers act as nucleating agents. Therefore, this invention can directly polymerize a well-crystallized furan-based polyester in one step, while avoiding the problem of adding other inorganic and organic nucleating agents, which could affect the performance of the furan-based polyester material. The process is simple and easy to implement. Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0048] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0049] In the polyester reaction system of the present invention, the amounts of the crystallization improver, the catalyst, and other components are all based on the weight of the generated polyester. It should be noted that the weight of the generated polyester refers to the weight of the polyester theoretically generated by the esterification of dicarboxylic acid and diol, and this theoretically generated polyester weight is determined based on the amount of raw materials.

[0050] In the embodiments and comparative examples of the invention, the raw materials are all derived from commercially available products.

[0051] 1,3-Dioxane-2-methanol (CAS: 5694-68-8), (1,3-dioxane-2-yl)methanol (CAS: 112474-18-7), 2-(1,3-dioxane-2-yl)ethanol (CAS: 5465-07-6), 1,3-dioxane-2-propane-1-ol (CAS: 85391-14-6), sodium benzoate, talc: purchased from Beijing Wokai Biotechnology Co., Ltd.

[0052] The methods used in the performance tests of the embodiments and comparative examples of the present invention are as follows:

[0053] Colorimetric analysis: The colorimetric properties of the polyester chips were tested according to the 5.5 colorimetric test method in GB / T 14190-2017, the analytical method for fiber-grade polyester chips. The dried polyester chips were heated at 135±5℃ for 60 min to crystallize them. After cooling, their B value was measured using a color-view colorimeter from BYK Gardner, Germany.

[0054] Intrinsic viscosity: The intrinsic viscosity of polyester chips was analyzed according to the test method of 5.1 intrinsic viscosity in GB / T 14190-2017, the analytical method for fiber-grade polyester chips. The solvent was a mixture of phenol and tetrachloroethane (chemically pure) (mass ratio 1:1), the test temperature was 25℃, and the polyester solution concentration was 0.005 g / mL.

[0055] Crystallization performance test: DSC test of the mixture was performed on a Discovery DSC model TA instrument. Take 6-10 mg of sample, and increase the temperature from 40℃ to 250℃ at a flow rate of 50 mL / min in a N2 atmosphere at 10℃ / min. Equilibrate for 5 minutes, then rapidly cool down to the crystallization temperature of 165℃ and crystallize for 1 hour to obtain the semi-crystallization time.

[0056] Transmittance: PEF polyester was hot-pressed at 220°C for 2 minutes on a flat vulcanizing machine and then quenched to obtain an amorphous film. The transmittance of the obtained sample was tested using a WGT-S type transmittance meter.

[0057] Example 1

[0058] 468 g (3 mol) of furanyl dicarboxylic acid, 297.6 g (4.8 mol, 1.6 eq) of ethylene glycol, 0.192 g of antimony glycol catalyst (based on the weight of the generated polyester, the weight of antimony atoms is 200 ppm, wherein the molar mass of the repeating unit of poly(ethylene furanyl dicarboxylic acid) is 182 g / mol, and the mass of 3 mol is 546 g), and 0.0546 g of 1,3-dioxane-2-methanol (based on 0.1‰ of the weight of the generated polyester, purchased from Beijing Wokai Biotechnology Co., Ltd.) were mixed to form a slurry, added to a polymerization reactor, and carried out an esterification reaction at a temperature of 230℃, a pressure of 0.25 MPa, and a time of 120 min. The water generated in the reaction was discharged through a distillation apparatus. After esterification, the pressure was reduced to normal, and then vacuumed until the system pressure was below 150 Pa. At the same time, the reaction temperature was gradually increased to 260 °C. The reaction was stopped after 120 min. The reaction product was then extruded from the bottom of the polymerization reactor, cooled, and pelletized to obtain the furanyl polyester product.

[0059] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0060] Example 2

[0061] The difference from Example 1 is that 0.1092 g of 1,3-dioxane-2-methanol (based on 0.2‰ of the weight of the polyester produced) was added;

[0062] All other conditions in Example 2 were the same as in Example 1, and a polyester product was obtained.

[0063] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0064] Example 3

[0065] The difference from Example 1 is that 0.273 g of 1,3-dioxane-2-methanol (based on 0.5‰ of the weight of the polyester produced) was added;

[0066] All other conditions in Example 3 were the same as in Example 1, and a polyester product was obtained.

[0067] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0068] Example 4

[0069] The difference from Example 1 is that 0.546 g of 1,3-dioxane-2-methanol (based on 1‰ of the weight of the generated polyester) was added;

[0070] All other conditions in Example 4 were the same as in Example 1, and a polyester product was obtained.

[0071] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0072] Example 5

[0073] The difference from Example 1 is that 1.092 g of 1,3-dioxane-2-methanol (based on 2‰ of the weight of the generated polyester) was added;

[0074] All other conditions in Example 5 were the same as in Example 1, and a polyester product was obtained.

[0075] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0076] Example 6

[0077] The difference from Example 1 is that 1.638 g of 1,3-dioxane-2-methanol (3‰ of the polyester weight) was added;

[0078] All other conditions in Example 6 were the same as in Example 1, and a polyester product was obtained.

[0079] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0080] Example 7

[0081] The difference from Example 1 is that 1,3-dioxane-2-methanol was replaced with 0.546 g of (4-methyl-1,3-dioxane-2-yl)methanol (purchased from Beijing Wokai Biotechnology Co., Ltd., based on 1‰ of the weight of the generated polyester);

[0082] All other conditions in Example 7 were the same as in Example 1, and a polyester product was obtained.

[0083] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0084] Example 8

[0085] The difference from Example 1 is that 1,3-dioxane-2-methanol was replaced with 0.546 g (1,3-dioxane-2-yl) methanol (based on 1‰ of the weight of the generated polyester, purchased from Beijing Wokai Biotechnology Co., Ltd.);

[0086] All other conditions in Example 8 were the same as in Example 1, and a polyester product was obtained.

[0087] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0088] Example 9

[0089] The difference from Example 1 is that 1,3-dioxane-2-methanol was replaced with 0.546 g of 2-(1,3-dioxane-2-yl)ethanol (purchased from Beijing Wokai Biotechnology Co., Ltd., based on 1‰ of the weight of the generated polyester);

[0090] All other conditions in Example 9 were the same as in Example 1, and a polyester product was obtained.

[0091] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0092] Example 10

[0093] The difference from Example 1 is that 1,3-dioxane-2-methanol was replaced with 0.546g of 1,3-dioxane-2-propane-1-ol (purchased from Beijing Wokai Biotechnology Co., Ltd., based on 1‰ of the weight of the generated polyester).

[0094] All other conditions in Example 10 were the same as in Example 1, and a polyester product was obtained.

[0095] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0096] Example 11

[0097] The difference from Example 4 is that 0.240g of antimony glycol catalyst was added (based on the weight of the generated polyester, the weight of antimony atoms is 250ppm);

[0098] All other conditions in Example 11 were the same as in Example 4, and a polyester product was obtained.

[0099] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0100] Example 12

[0101] 468 g (3 mol) of furanyl dicarboxylic acid, 478.8 g (6.3 mol, 2.1 eq) of 1,3-propanediol, 0.206 g of antimony glycol catalyst (based on the weight of the polyester produced, the weight of antimony atoms is 200 ppm, wherein the molar mass of the repeating unit of poly(propylene furanyl dicarboxylate) is 196 g / mol, and the mass of 3 mol is 588 g); and 0.588 g of 1,3-dioxane-2-methanol (based on 1‰ of the weight of the polyester produced, purchased from Beijing Wokai Biotechnology Co., Ltd.) were mixed to form a slurry, added to a polymerization reactor, and carried out an esterification reaction at a temperature of 235℃, a pressure of atmospheric pressure, and a time of 100 min. The water generated in the reaction was discharged through a distillation apparatus. After esterification, the system pressure was reduced to below 150 Pa, while the reaction temperature was gradually increased to 250 °C. The reaction was stopped after 150 min. The reaction product was then extruded from the bottom of the polymerization reactor, cooled, and pelletized to obtain the furanyl polyester product.

[0102] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0103] Example 13

[0104] The difference from Example 4 is that the polycondensation temperature is 265°C;

[0105] All other conditions in Example 13 were the same as in Example 4, and a polyester product was obtained.

[0106] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0107] Example 14

[0108] The difference from Example 4 is that the molar ratio of furanyl dicarboxylic acid and ethylene glycol is 1:1.4;

[0109] All other conditions in Example 14 were the same as in Example 4, and a polyester product was obtained.

[0110] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0111] Example 15

[0112] The difference from Example 4 is that the catalyst was replaced with 0.016 g of tetraisopropyl titanate (based on the weight of the generated PEF polyester, the weight of titanium atoms was 5 ppm) and 0.546 g of 1,3-dioxane-2-methanol (based on 1‰ of the weight of the generated polyester, purchased from Beijing Wokai Biotechnology Co., Ltd.).

[0113] All other conditions in Example 15 were the same as in Example 4, and a polyester product was obtained.

[0114] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0115] Example 16

[0116] 552 g (3 mol) of dimethyl furanate, 372 g (6 mol, 2.0 eq) of ethylene glycol, 0.24 g of zinc acetate (based on the weight of the generated PEF polyester, the weight of zinc atoms is 156 ppm), and 0.546 g of 1,3-dioxane-2-methanol (based on 1.0‰ of the weight of the generated polyester, purchased from Beijing Wokai Biotechnology Co., Ltd.) were mixed to form a slurry, which was then added to a polymerization reactor for an atmospheric pressure transesterification reaction at a temperature of 160–230 °C for 120 min. The water generated in the reaction was removed by distillation. After esterification, the pressure was reduced to atmospheric pressure and then evacuated to a vacuum pressure below 150 Pa. Simultaneously, the reaction temperature was gradually increased to 260 °C. The reaction was stopped after 120 min, and the reaction product was then extruded from the bottom of the polymerization reactor.

[0117] Comparative Example 1

[0118] The difference from Example 1 is that 1,3-dioxane-2-methanol was not added;

[0119] All other conditions in Comparative Example 1 were the same as in Example 1, and a polyester product was obtained.

[0120] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0121] Comparative Example 2

[0122] The difference from Example 4 is that the crystallization improver 1,3-dioxane-2-methanol was replaced with 0.546g sodium benzoate (based on 1‰ of the weight of the generated polyester, purchased from Beijing Wokai Biotechnology Co., Ltd.);

[0123] All other conditions in Comparative Example 2 were the same as in Example 1, and a polyester product was obtained.

[0124] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0125] Comparative Example 3

[0126] The difference from Example 4 is that the crystallization improver 1,3-dioxane-2-methanol was replaced with 0.546g of talc powder (based on 1‰ of the weight of the generated polyester, purchased from Beijing Wokai Biotechnology Co., Ltd.);

[0127] All other conditions in Comparative Example 3 were the same as in Example 1, and a polyester product was obtained.

[0128] The performance of the furan-based polyester material prepared in this embodiment was tested, and the test results are detailed in Table 1.

[0129] The intrinsic viscosity, hue B value, semi-crystallization time, and visible light transmittance of the polyester materials prepared in Examples 1-16 and Comparative Examples 1-3 were tested, and the test results are shown in Table 1 below.

[0130] Table 1:

[0131]

[0132] According to the data in Table 1,

[0133] The half-crystallization time of the furan-based polyester materials prepared in Examples 1-16 was 4.6-7.6 min, while the half-crystallization time of the furan-based polyester material prepared in Comparative Example 1 without the addition of a crystallization improver was 30 min. It is evident that the crystallization improver provided by this invention can significantly improve crystallization performance.

[0134] Compared to Examples 4 and 7-10, Comparative Example 2, which replaced the crystallization improver with an equal mass of sodium benzoate, yielded a polyester material with a semi-crystallization time of 18 min, significantly higher than the 5.2-5.6 min of Examples 4 and 7-10. This demonstrates that the crystallization improver provided by this invention can significantly improve crystallization performance compared to sodium benzoate. Simultaneously, the hue B value of the polyester material in Comparative Example 2 was 8.1, significantly higher than the 2.7-2.9 of Examples 4 and 7-10; the light transmittance of the polyester material in Comparative Example 2 was 86%, significantly lower than the 92-94% of Examples 4 and 7-10. This demonstrates that, compared to sodium benzoate, the crystallization improver provided by this invention can better guarantee the hue and light transmittance of the polyester material without affecting the quality of the furanyl polyester product.

[0135] Compared to Examples 4 and 7-10, Comparative Example 3, which replaced the crystallization improver with an equal mass of talc, yielded a polyester material with a semi-crystallization time of 16 min, significantly higher than the 5.2-5.6 min of Examples 4 and 7-10. This demonstrates that the crystallization improver provided by this invention can significantly improve crystallization performance compared to talc. Simultaneously, the hue B value of the polyester material in Comparative Example 3 was 3.6, an improvement over Comparative Example 2, but still slightly higher than the 2.7-2.9 of Examples 4 and 7-10. The light transmittance of the polyester material in Comparative Example 3 was 85%, significantly lower than the 92-94% of Examples 4 and 7-10. This demonstrates that, compared to talc, the crystallization improver provided by this invention can better guarantee the hue and light transmittance of the polyester material without affecting the quality of the furan-based polyester product.

[0136] The highly crystalline furan-based polyesters prepared in Examples 1-16 have intrinsic viscosities of 0.648-0.671 dL / g, hue B values ​​of 2.4-5.8, and semi-crystallization times of 4.6-7.6 min. This demonstrates that by introducing a crystallization modifier into the reaction system, the prepared highly crystalline furan-based polyesters exhibit good color value and transparency, as well as excellent crystallinity. The preparation method of this invention allows for the direct in-situ polymerization of highly crystalline furan-based polyesters in a single step, while avoiding the problems associated with the secondary addition of other inorganic and organic nucleating agents that could affect the performance of the furan-based polyester materials. The process is simple and easy to implement.

[0137] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A highly crystalline furan-based polyester, wherein the highly crystalline furan-based polyester is prepared in the presence of a crystallization improver; wherein the crystallization improver is at least one of cyclic monohydroxy acetal compounds.

2. The highly crystalline furan-based polyester as described in claim 1, characterized in that: The crystallization improver is at least one selected from 1,3-dioxane-2-methanol, (4-methyl-1,3-dioxane-2-yl)methanol, (1,3-dioxane-2-yl)methanol, 2-(1,3-dioxane-2-yl)ethanol, and 1,3-dioxane-2-propane-1-ol; and / or The highly crystalline furan-based polyester is obtained by reacting components including furan diacid or its derivatives and diols in the presence of a crystallization improver; preferably, the furan diacid or its derivatives are at least one of furan dicarboxylic acid and dimethyl furan dicarboxylate; and / or, the diol is at least one of alkylene glycols, preferably at least one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, 1,4-cyclohexanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

3. The highly crystalline furan-based polyester as described in claim 1 or 2, characterized in that: The intrinsic viscosity of the highly crystalline furan-based polyester is greater than 0.6 dl / g; and / or, The highly crystalline furan-based polyester exhibits an isothermal semi-crystallization time of ≤10 min at 165°C; and / or, The visible light transmittance of the highly crystalline furan-based polyester is above 90%.

4. A method for preparing a highly crystalline furanyl polyester as described in any one of claims 1 to 3, comprising the following steps: The highly crystalline furan-based polyester is prepared by reacting components including furan dicarboxylic acid or its derivatives and diols in the presence of a crystallization improver.

5. The method for preparing highly crystalline furan-based polyester as described in claim 4, characterized in that: The molar ratio of the furan diacid or its derivative to the diol is 1:(1.05–2.5); preferably 1:(1.3–2.1); and / or, The amount of the crystallization improver is 0.05 to 10‰ of the weight of the generated highly crystalline furan-based polyester, preferably 0.1 to 3‰.

6. The method for preparing highly crystalline furan-based polyester as described in claim 4, characterized in that: The reaction is carried out in the presence of a catalyst, preferably at least one of antimony-based catalysts, titanium-based catalysts, and other metal-based catalysts; the antimony-based catalyst is more preferably at least one of antimony glycolate, antimony acetate, and antimony trioxide; the titanium-based catalyst is more preferably at least one of tetraisopropyl titanate and tetrabutyl titanate; and the other metal-based catalyst is more preferably at least one of zinc acetate, zinc oxide, and germanium oxide.

7. The method for preparing highly crystalline furan-based polyester as described in claim 6, characterized in that: When an antimony-based catalyst is added, the weight of antimony atoms in the catalyst is 50–500 ppm of the weight of the generated highly crystalline furanyl polyester; preferably 200–250 ppm; and / or, When a titanium-based catalyst is added, the weight of titanium atoms in the catalyst is 2 to 20 ppm of the weight of the generated highly crystalline furanyl polyester; preferably 5 to 10 ppm; and / or, When other metal-based catalysts are added, the weight of the metal atoms in the other metal-based catalysts is 2 to 500 ppm of the weight of the generated highly crystalline furanyl polyester; preferably 5 to 300 ppm.

8. The method for preparing highly crystalline furan-based polyester as described in claim 4, characterized in that: The reaction involves first performing an esterification reaction to obtain an esterified product, followed by a polycondensation reaction to obtain the highly crystalline furan-based polyester; preferably, The esterification reaction conditions are: reaction temperature of 135–240℃, reaction pressure of 0–0.35 MPa, and reaction time of 90–130 min; preferably: reaction temperature of 150–240℃, reaction pressure of 0–0.28 MPa, and reaction time of 100–120 min; and / or, The conditions for the polycondensation reaction are: reaction temperature of 230-270℃, reaction pressure of 0-0.5 MPa, and reaction time of 60-180 min; preferably: reaction temperature of 235-265℃, reaction pressure of 0-150 Pa, and reaction time of 100-150 min.

9. A highly crystalline furan-based polyester obtained by the preparation method according to any one of claims 4 to 8; preferably, The intrinsic viscosity of the highly crystalline furan-based polyester is greater than 0.6 dl / g; and / or, The highly crystalline furan-based polyester exhibits an isothermal semi-crystallization time of ≤10 min at 165°C; and / or, The visible light transmittance of the highly crystalline furan-based polyester is above 90%.

10. The use of a highly crystalline furanyl polyester as described in any one of claims 1 to 3, 9 in resin products, preferably in resin fibers, resin films, and resin bottles.

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