[0028] The preparation method of furan-based copolyester provided by the invention comprises:
[0029] (1) 2,5-furandicarboxylic acid or its esterified product, bis[4-(2-hydroxyethoxy)phenyl]sulfone, cyclohexanedimethanol, aliphatic hydrocarbon glycol and an esterification catalyst are mixed, and The esterification reaction is carried out to obtain the first intermediate product, wherein the structural formula of the bis[4-(2-hydroxyethoxy)phenyl]sulfone is shown in the following formula (2):
[0030]
[0031] (2) The first intermediate product is subjected to a polycondensation reaction to obtain a furan-based copolyester, wherein the structural formula of the furan-based copolyester is shown in the following formula (1):
[0032]
[0033] Wherein, x, y, and z are all integers from 1 to 20, n is an integer from 10 to 100, and R 1 For the structural unit corresponding to aliphatic hydrocarbon diol, the R 1 The chemical structural formula is -(CH 2 ) m -, m is an integer from 2 to 10, R 2 is a structural unit corresponding to cyclohexanedimethanol, the R 2 The chemical structural formula is -C 8 H 14 O 2 -.
[0034] In step (1), 2,5-furandicarboxylic acid is a stable furan derivative, has two carboxyl groups, and is a cyclic conjugated system, but its horizontal axis is asymmetric and the space packing density is low, so, 2,5-Furandicarboxylic acid has high rigidity, Tg is about 87℃, but the melting temperature is about 217℃. Therefore, on this basis, only a small amount of rigid segments of bis[4-(2-hydroxyethoxy)phenyl]sulfone can be introduced to prepare high Tg copolyesters, and due to the melting of the base The temperature is low, and the processing temperature of the copolyester is increased after the rigid segment of bis[4-(2-hydroxyethoxy)phenyl]sulfone is introduced, but it will not exceed 300 °C. Therefore, the preparation of the copolyester is more efficient. Controllable and better transparency.
[0035] Specifically, the molar ratio of 2,5-furandicarboxylic acid or its ester compound to the bis[4-(2-hydroxyethoxy)phenyl]sulfone is preferably 1:(0.1-0.9), preferably 1 : (0.4~0.6).
[0036] Specifically, the esterified product of 2,5-furandicarboxylic acid includes dimethyl 2,5-furandicarboxylate and the like. Considering the good reactivity of dimethyl 2,5-furandicarboxylate, the present invention preferably adopts dimethyl 2,5-furandicarboxylate.
[0037] In addition, the present invention also uses part of the cyclohexanedimethanol to replace the aliphatic hydrocarbon diol. Because when cyclohexanedimethanol is copolymerized with 2,5-furandicarboxylic acid or its esters, the molecules of cyclohexanedimethanol can break the regular structure of the molecular chain to obtain an amorphous furan-based copolyester, which not only has It is beneficial to injection molding, and can slow down the thermal crystallization of the copolyester in the injection molding process, thereby improving the transparency of the furan-based copolyester.
[0038] Moreover, the steric hindrance of the six-membered ring of cyclohexanedimethanol is relatively large, which makes the oxygen and hydrogen atoms of the hydroxyl groups on the methyl group have higher bond energy. The reactivity rate is higher, which can improve the reactivity.
[0039] At the same time, the non-planar six-membered ring structure of cyclohexanedimethanol can make the copolyester molecules more closely arranged, thereby effectively improving the toughness and impact strength of the furan-based copolyester. And with the increase of cyclohexanedimethanol, the esterification reaction activity with 2,5-furandicarboxylic acid or its ester compound is improved, and the toughness of the obtained furan-based copolyester is enhanced, so that the furan-based copolyester can be used in complex materials. The shape of the product is processed to meet the special purpose of the industry, and the processed product is not easy to crack. During the application process, the product has a high safety factor and a long service life.
[0040] Specifically, the cyclohexanedimethanol includes at least one of 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,2-cyclohexanedimethanol.
[0041]Among them, the greater the proportion of 1,4-cyclohexanedimethanol, the greater the relative molecular weight of the furan-based copolyester and the higher the intrinsic viscosity. Moreover, the 1,4-cyclohexanedimethanol molecule has a high degree of symmetry, which can make the arrangement of furan-based copolyester molecular chains more closely, which is more helpful to improve the crystallization properties and toughness of the copolyester molecule, thereby improving furan-based copolyester molecules. Thermal stabilization of base copolyesters. Therefore, the cyclohexanedimethanol is preferably 1,4-cyclohexanedimethanol.
[0042] When using cyclohexanedimethanol to improve the properties of furan-based copolyester, considering that the amount of cyclohexanedimethanol is too low, the toughness of furan-based copolyester is not significantly improved, but when the amount is too large, it will lead to Furan-based copolyesters do not crystallize at all and cannot meet practical needs. Therefore, the molar ratio of 2,5-furandicarboxylic acid or its ester product to cyclohexanedimethanol is preferably 1:(0.1 to 0.5), more preferably 1:(0.2 to 0.4).
[0043] Specifically, the aliphatic hydrocarbon diol is mainly used to increase the relative molecular weight of the furan-based copolyester, including ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, At least one of 1,10-decanediol and neopentyl glycol.
[0044] Considering that the molar ratio of aliphatic hydrocarbon diol and 2,5-furandicarboxylic acid or its ester is too high, aliphatic hydrocarbon diol will produce self-polycondensation reaction at high temperature, so that the proportion of by-products in the first intermediate product increases, It is not conducive to the synthesis of the target product. However, if the molar ratio of aliphatic hydrocarbon diol and 2,5-furandicarboxylic acid or its ester product is too low, the esterification reaction rate will be reduced and the reaction time will be prolonged. Therefore, under the full use of the raw material molar ratio reaction advantages, the by-products can be controlled more effectively. The molar ratio of the total amount of the alcohol to the 2,5-furandicarboxylic acid or its ester product can regulate the esterification reaction rate and improve the yield of the first intermediate product.
[0045] Preferably, the sum of the amounts of the bis[4-(2-hydroxyethoxy)phenyl]sulfone, the cyclohexanedimethanol and the aliphatic hydrocarbon diol is the same as the amount of the 2,5-furandiol. The molar ratio of the amount of formic acid or its esterified product to be used is (1.1 to 2.2):1, more preferably (1.5 to 1.8):1.
[0046] Specifically, the esterification catalyst includes at least one of zinc acetate, isobutyl titanate, and tetrabutyl titanate. Appropriate catalysts can increase the speed of the reaction and reduce the time of esterification, but too high catalyst dosage will also accelerate the occurrence of side reactions. Therefore, considering the esterification reaction rate, the amount of the esterification catalyst used is 0.05%-0.3%, preferably 0.1%-0.2%, of the molar amount of 2,5-furandicarboxylic acid or its esterified product.
[0047] Specifically, under the action of an esterification catalyst, 2,5-furandicarboxylic acid or its esterified product is subjected to an esterification reaction with cyclohexanedimethanol to form an ester group, and 2,5-furandicarboxylic acid or its esterified product also It is esterified with bis[4-(2-hydroxyethoxy)phenyl]sulfone and aliphatic hydrocarbon diol to form an ester group, the bis[4-(2-hydroxyethoxy)phenyl]sulfone, The cyclohexanedimethanol and the aliphatic hydrocarbon diol are connected with the 2,5-furandicarboxylic acid or its ester through an ester group to form a first intermediate product.
[0048] Considering that the esterification reaction is an endothermic reaction, the temperature of the esterification reaction needs to be reasonably regulated. A reasonable reaction temperature can not only improve the solubility of the whole system, but also promote the esterification reaction and improve the esterification rate. Therefore, the esterification reaction of step (1) is maintained in an atmosphere of inert gas, and the reaction temperature is 160°C to 220°C, preferably 180°C to 200°C. The reaction time is 2 hours to 6 hours, preferably 4 hours to 5 hours.
[0049] In step (2), the temperature of the polycondensation reaction is 220°C to 300°C, preferably 235°C to 270°C, and the reaction time is 2 hours to 6 hours, preferably 4 hours to 6 hours. Due to the low melting temperature of the polyester obtained by the reaction of 2,5-furandicarboxylic acid with diols, the processing temperature remains low after the introduction of rigid bis[4-(2-hydroxyethoxy)phenyl]sulfone At 300 ℃, it is favorable for the preparation of copolyester.
[0050] Specifically, the polycondensation reaction is carried out in a vacuum environment. Among them, in the polycondensation stage, the high degree of vacuum is beneficial to the discharge of by-products generated by polycondensation, thereby obtaining a polyester product with high viscosity. However, in the polycondensation reaction, an excessively high degree of vacuum will cause the low-viscosity copolymer to be drawn out, block the pipeline, and require higher equipment, which increases the production cost. Therefore, in order to ensure the quality of the copolyester product, the vacuum degree of the polycondensation reaction can be gradually and slowly reduced, so that the vacuum degree can be reduced to 100Pa and below.
[0051] Specifically, when performing the polycondensation reaction, it also includes adding a polycondensation reaction catalyst to the first intermediate product, and the polycondensation reaction catalyst includes antimony trioxide, isobutyl titanate, tetrabutyl titanate, ethylene glycol At least one of antimony, antimony acetate, and dibutyltin oxide, stannous isooctoate, monobutyltin triisooctoate, dioctyltin oxide, and polyethylene glycol antimony. Preferably, the amount of the polycondensation catalyst used is 0.05% to 0.3% of the molar amount of the 2,5-furandicarboxylic acid or its ester product, preferably 0.1% to 0.2%.
[0052] It is understood that when the esterification catalyst is tetrabutyl titanate, the esterification catalyst can also be used as the polycondensation catalyst. At this time, the first intermediate product can be directly subjected to the polycondensation reaction of step (2). However, after considering the esterification reaction, the esterification catalyst will partially fail. Therefore, when the esterification catalyst and the polycondensation catalyst are the same, a part of the polycondensation catalyst may be added to the first intermediate product before the polycondensation reaction in step (2).
[0053] Specifically, during the polycondensation reaction, a stabilizer is also added. The stabilizer can reduce the oxidative cleavage of ester bonds, aliphatic chains and carbon-carbon bonds under oxygen and prevent thermal decomposition. The stabilizer includes phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, ammonium phosphate, trimethyl phosphate, dimethyl phosphate, triphenyl phosphate, diphenyl phosphate, triphenyl phosphite, diphenyl phosphite The amount of at least one of ester, ammonium phosphite and ammonium dihydrogen phosphate is 0.05% to 0.3% of the molar amount of the 2,5-furandicarboxylic acid or its ester product, more preferably 0.10% to 0.15%.
[0054] Specifically, during the polycondensation reaction, an antioxidant can also be added, and the antioxidant can capture oxygen free radicals and eliminate a trace amount of oxygen, thereby reducing the occurrence of thermal decomposition reactions and oxidation side reactions. The antioxidant includes at least one of antioxidant-1010, antioxidant-1076, and antioxidant-168, and the dosage is 0.05%~0.05% of the molar amount of the 2,5-furandicarboxylic acid or its ester compound 0.3%, more preferably 0.10% to 0.15%.
[0055] In addition, the present invention also provides a furan-based copolyester obtained by the above preparation method, and the structural formula of the furan-based copolyester is shown in the following formula (1):
[0056]
[0057] Wherein, x, y, and z are all integers from 1 to 20, n is an integer from 10 to 100, and R 1 For the structural unit corresponding to aliphatic hydrocarbon diol, the R 1 The chemical structural formula is -(CH 2 ) m -, m is an integer from 2 to 10, R 2 is the structural unit corresponding to cyclohexanedimethanol, the chemical structure is -C 8 H 14 O 2 -.
[0058] Specifically, R 1 include at least one of them.
[0059] Specifically, R 2 At least one of the structural unit of 1,4-cyclohexanedimethanol, the structural unit of 1,3-cyclohexanedimethanol, and the structural unit of 1,2-cyclohexanedimethanol is included.
[0060] Taking into account the symmetry of the molecule and the toughness of the copolyester, R 2 It is preferably a structural unit of 1,4-cyclohexanedimethanol. At this time, the structural formula of the furan-based copolyester is shown in the following (3):
[0061]
[0062] The glass transition temperature of the furan-based copolyester of the structural formula of the present invention can reach 90° C. to 120° C., so that it has the characteristics of excellent heat resistance, mechanical properties and transparency. Furthermore, by adjusting the -R 2 -and-R 1 - The molar ratio of the structural units can adjust the glass transition temperature of the furan-based copolyester of the present invention.
[0063] preferably, when -R 2 -and-R 1 When the molar ratio of the structural units of - is (50-60): (20-40): (10-20), the glass transition temperature of the furan-based copolyester of the present invention can reach 100 ℃~120 ℃, and as the increases with the increase of the molar ratio.
[0064] Therefore, the furan-based copolyester provided by the present invention not only has a high glass transition temperature, but also has strong toughness, and has the characteristics of strong heat resistance, high thermal stability, good mechanical properties, high transparency, green environmental protection, etc. , children's toys, water cups, kitchen appliances, food packaging, electronic appliances, optics, decorative materials, automobile manufacturing and other fields of manufacturing requirements, but also has special uses for lightweight bulletproof glass collars.
