Furan polyester composition and use thereof

Abstract

Disclosed is a furan polyester composition, the furan polyester composition being mainly composed of 2,5-furandicarboxylic acid structural units and aliphatic diol structural units, and the polyester composition containing germanium and phosphite antioxidants. The furan polyester composition exhibits a color tone, heat resistance, and crystallinity that are all good, and can be used to prepare fibers, films, engineering plastics, and the like.

Description

Furan polyester compositions and their applications Technical Field

[0001] This invention relates to a furan polyester composition, specifically, to a furan polyester composition with excellent heat resistance, color tone, and crystallinity. Background Technology

[0002] 2,5-Furandicarboxylic acid (FDCA) is a stable furan derivative with wide availability, obtained from biomass such as fruit shells and straw. Structurally, FDCA is similar to aromatic dicarboxylic acids such as terephthalic acid, both possessing a cyclic conjugated system and two reactive groups. Therefore, it is speculated that the high-molecular-weight furan polyesters obtained by reacting FDCA with aliphatic diols will have similar properties to aromatic polyesters. Thus, 2,5-Furandicarboxylic acid is a powerful substitute for aromatic dicarboxylic acids in the production of high-performance polymers.

[0003] Chinese patent CN103665355A discloses a method for preparing a highly hydrophilic, fully bio-based polyester. The method involves preparing a slurry by mixing bio-based 2,5-furanidic acid and a polyol at a mass ratio of 1:1.05–1.5, which is then added to an esterification reactor for esterification. This is followed by a polycondensation reaction to obtain the biomass polyester. At least one of a titanium-based catalyst and an antimony-based catalyst, along with a heat stabilizer and an antioxidant, are added during the esterification reaction. However, the carboxyl group in 2,5-furanidic acid has poor thermal stability and undergoes ring-opening to form free radicals during high-temperature polymerization, resulting in a darker polyester color. Furthermore, titanium-based and antimony-based catalysts easily induce side reactions, negatively impacting the polyester's color and heat resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a furan polyester composition that simultaneously possesses good color tone, heat resistance, and crystallinity, and that can be used to prepare fibers, films, engineering plastics, etc.

[0005] The technical solution of the present invention is:

[0006] The furan polyester composition is mainly composed of 2,5-furan dicarboxylic acid structural units and aliphatic diol structural units, and the polyester composition contains germanium and phosphite antioxidants.

[0007] The phosphite antioxidant is preferably one or more of the antioxidants shown in Formula 1, Formula 2 or Formula 3.

[0008]

[0009] In Equation 1, R 1 R 2They are phenyl, alkyl with 2 to 30 carbon atoms, or aromatic alkyl with 7 to 30 carbon atoms, respectively; in Formula 2, R 3 It is a phenyl, biphenyl, alkylene group with 2 to 30 carbon atoms, or aromatic alkyl group with 7 to 12 carbon atoms, R 4 ~R 7 They are phenyl, alkyl with 2 to 30 carbon atoms, or aromatic alkyl with 7 to 12 carbon atoms, respectively; in formula 3, R 8 ~R 10 They are alkyl groups with 2 to 30 carbon atoms, respectively.

[0010] The germanium element preferably accounts for 5 to 1000 ppm of the total amount of the furan polyester composition, and more preferably 5 to 700 ppm of the total amount of the furan polyester composition.

[0011] The total content of the phosphite antioxidants, calculated based on phosphorus, is preferably 0.0010 to 0.5000 wt% of the total weight of the furan rings, and more preferably 0.0010 to 0.1000 wt% of the total weight of the furan rings.

[0012] The molar ratio of the phosphite antioxidant to the germanium element, calculated as phosphorus, is preferably 0.10 or higher.

[0013] The aliphatic diol structural unit is preferably one or more of ethylene glycol structural units, propylene glycol structural units, butanediol structural units, and pentanediol structural units.

[0014] The content of the dimer of the aliphatic diol is preferably below 2.2 wt%.

[0015] This invention utilizes a germanium catalyst and a phosphite antioxidant to obtain a furan polyester composition with good color, heat resistance, and crystallinity, suitable for the manufacture of fibers, films, engineering plastics, etc. Attached Figure Description

[0016] Figure 1 is a schematic diagram showing a thermal characteristic curve used in the crystallinity test of this invention.

[0017] In Figure 1, A represents the crystallization peak, and S represents the peak. A The peak area of ​​the crystallization peak and the half-crystallization time are T1-T0. Detailed Implementation

[0018] The furan polyester composition described in this invention mainly refers to a polyester composition obtained by esterification-condensation or transesterification-condensation of 2,5-furandicarboxylic acid or its esterified derivatives with an aliphatic diol. The 2,5-furandicarboxylic acid or its esterified derivatives are mainly 2,5-furandicarboxylic acid, dimethyl 2,5-furandicarboxylate, diethyl 2,5-furandicarboxylate, etc. The aliphatic diol mainly refers to straight-chain aliphatic diols such as ethylene glycol, propylene glycol, butanediol, and pentanediol. Specifically, the furan polyester composition may include polyethylene furanate (PEF), propylene furanate (PPF), and butylene furanate (PBF).

[0019] In existing technologies, antimony-based or titanium-based catalysts are commonly used in the preparation of furan polyesters. Antimony-based catalysts promote the formation of colored organic byproducts (such as conjugated compounds with unsaturated bonds), reducing the color of the furan polyester composition. Antimony-based catalysts can also be reduced to elemental antimony, causing contamination of the spinning components and affecting the preparation of furan polyesters and the production of furan polyester products. Titanium-based catalysts, on the other hand, have high catalytic activity against side reactions, resulting in furan polyesters that exhibit severe yellowing and poor heat resistance.

[0020] The germanium-based catalyst used in the furan polyester composition of the present invention has good catalytic activity. Compared with other catalysts, it has a milder catalytic activity on side reactions, causes virtually no pollution to the spinning components, and the resulting furan polyester composition has good color and heat resistance.

[0021] The germanium-based catalyst refers to a substance that exhibits catalytic activity during the polyester reaction process, such as germanium dioxide, germanium monoxide, germanium disulfide, germanium monosulfide, germanium selenide, germanium chloride, germanium fluoride, tetraethyl germanium, n-butyl germanium, isobutyl germanium, etc. Considering factors such as product stability and cost, germanium dioxide is the preferred germanium-based catalyst described in this invention.

[0022] The germanium content in the furan polyester composition of this invention should not be too high, meaning the amount of germanium-based catalyst added during the reaction should not be too large. Otherwise, the polymerization side reaction rate will accelerate, the number of side reaction products will increase, the heat resistance and color of the furan polyester composition will deteriorate, and the cost will also increase. Conversely, the germanium content should not be too low, meaning the amount of germanium-based catalyst added during the reaction should not be too small. Otherwise, the polymerization reaction will be too slow and difficult to proceed. Therefore, a suitable amount of germanium-based catalyst should be selected to ensure the smooth progress of the polymerization reaction while minimizing the content of side reaction products in the resulting furan polyester composition. Considering catalytic activity, the formation of side reaction products, and cost, the amount of germanium-based catalyst added is preferably equivalent to 10–2000 ppm of the furan polyester composition, more preferably 10–1400 ppm, calculated as germanium. Considering that some germanium-based catalyst will be extracted along with the diol during the polymerization reaction, the germanium content in the furan polyester composition obtained after adding the germanium-based catalyst within the preferred range is 5–1000 ppm, more preferably 5–700 ppm.

[0023] Because the furan rings in the furan polyester composition are prone to decomposition at high temperatures, generating free radicals, these free radicals react with oxygen to cause yellowing, resulting in a deterioration in the color of the furan polyester composition. Furthermore, the furan polyester composition undergoes degradation under the action of a catalyst after heating, primarily manifested as ester bond breakage and molecular weight reduction, leading to decreased strength and heat resistance. Simultaneously, due to the presence of polymerization side reactions, the furan polyester composition often contains low-molecular-weight substances (such as dimers of aliphatic diols, cyclic oligomers, etc.) or cross-linking substances (such as cross-linked structures formed by free radical coupling). These substances hinder the orderly arrangement of furan polyester molecular chains, resulting in decreased heat resistance, slow crystallization rate, and deteriorated crystallization performance. This further leads to the easy adhesion of furan polyester chips during subsequent drying processes, affecting productivity.

[0024] In addition to selecting germanium-based catalysts, this invention also reduces the impact of thermal oxidation on the strength, heat resistance, chip crystallinity, color, and other physical properties of the furan polyester composition by using phosphite antioxidants.

[0025] The phosphite antioxidant can coordinate with the furan ring, inhibiting the decomposition of the furan ring; for the free radicals that have already been generated, the phosphite antioxidant can coordinate with them, preventing the free radicals from reacting with oxygen to form yellowing substances, thereby improving the color tone of the furan polyester composition.

[0026] The phosphite antioxidant is preferably one or more of the antioxidants shown in Formula 1, Formula 2 or Formula 3.

[0027]

[0028] In Equation 1, R 1 R 2 They are phenyl, alkyl with 2 to 30 carbon atoms, or aromatic alkyl with 7 to 30 carbon atoms, respectively; in Formula 2, R 3 It is a phenyl, biphenyl, alkylene group with 2 to 30 carbon atoms, or aromatic alkyl group with 7 to 12 carbon atoms, R 4 ~R 7 They are phenyl, alkyl with 2 to 30 carbon atoms, or aromatic alkyl with 7 to 12 carbon atoms, respectively; in formula 3, R 8 ~R 10 They are alkyl groups with 2 to 30 carbon atoms, respectively.

[0029] To reduce the steric hindrance of phosphite antioxidants and facilitate the formation of coordination structures between the antioxidants and furan rings, R in Formula 2 is further preferred. 4 ~R 7 It does not contain aromatic rings simultaneously. This allows the antioxidant effect of phosphite antioxidants to be fully utilized, thereby improving the color and heat resistance of the furan polyester composition. By reducing the steric hindrance of phosphite antioxidants, the compatibility between phosphite antioxidants and furan polyester compositions can also be improved, preventing phosphite antioxidants from becoming foreign substances in the furan polyester composition.

[0030] The antioxidants shown in Formulas 1 to 3 can be specifically listed as follows: antioxidant A as shown in Formula 4, antioxidant B as shown in Formula 5, antioxidant C as shown in Formula 6, antioxidant D as shown in Formula 7, antioxidant E as shown in Formula 8, antioxidant F as shown in Formula 9, antioxidant G as shown in Formula 10, antioxidant H as shown in Formula 11, and antioxidant I as shown in Formula 12, etc.

[0031]

[0032]

[0033]

[0034] When using antioxidants, you can use a single phosphite antioxidant, or you can use two or three at the same time.

[0035] The functions of the phosphite antioxidants include inhibiting furan ring decomposition and scavenging free radicals. Studies on the decomposition probability of furan rings and the efficiency of the antioxidants in their effects on furan rings and free radicals revealed that the phosphite antioxidants achieve optimal effects when the phosphorus content in the phosphite antioxidants is equivalent to 0.0010–0.5000 wt% of the total weight of the furan rings. The total weight of the furan rings refers to the total weight of all furan rings in the furan polyester composition. If the phosphorus content in the phosphite antioxidants is less than 0.0010 wt% relative to the total weight of the furan rings, the resulting furan polyester composition tends to exhibit decreased color hue and heat resistance. If the phosphorus content in the phosphite antioxidant is higher than 0.5000 wt% relative to the total weight of the furan rings, the excess phosphite antioxidant in the furan polyester composition tends to increase as all the furan rings and free radicals have coordinated with the phosphite antioxidant. This excess phosphite antioxidant may form foreign matter in the furan polyester composition, leading to an increased frequency of cleaning the film-forming equipment during film formation and a higher probability of antioxidant leakage after film formation. To further ensure that the furan polyester composition has excellent color and heat resistance, and that the phosphite antioxidant is not excessive, it is more preferable that the phosphorus content in the phosphite antioxidant is equivalent to 0.0010–0.1000 wt% of the total weight of the furan rings.

[0036] Another function of the phosphite antioxidants described in this invention is to inhibit the catalytic activity of germanium-based catalysts for side reactions by coordinating with them, thereby improving the crystallinity of the furan polyester composition, reducing the adhesion of furan polyester chips in subsequent drying processes, and improving productivity. Simultaneously, after coordinating with the phosphite antioxidants, the activity of the germanium-based catalysts is also reduced, weakening the degradation catalysis of the furan polyester composition, thus improving the heat resistance of the furan polyester composition.

[0037] Through research on a series of factors, including the magnitude of side reaction catalytic activity of germanium-based catalysts, degradation reaction characteristics of furan polyester compositions, the effect of coordination between phosphite antioxidants and germanium-based catalysts on the polymerization catalytic activity of germanium-based catalysts, and the crystallization rate of furan polyester compositions, this invention preferably uses a molar ratio of the phosphite antioxidant (based on phosphorus) to germanium in the germanium-based catalyst of 0.10 or higher. As the aforementioned molar ratio decreases, the heat resistance, anti-yellowing effect, and crystallinity of the resulting furan polyester compositions tend to decline. To further improve the heat resistance, anti-yellowing effect, and crystallinity of the furan polyester compositions, the molar ratio of the phosphite antioxidant (based on phosphorus) to germanium is more preferably 0.80 or higher.

[0038] During the preparation of furan polyester compositions, dimers of aliphatic diols are typically generated. For example, when ethylene glycol is used as the aliphatic diol, diethylene glycol (an ethylene glycol dimer) is generated; when 1,3-propanediol is used as the aliphatic diol, dipropylene glycol (a propylene glycol dimer) is generated, and so on. These dimers result in irregular structures and low crystallinity in the furan polyester composition, easily causing the furan polyester chips to stick together during subsequent drying processes, thus affecting productivity. Therefore, to ensure the productivity of the furan polyester composition, the content of the aliphatic diol dimer is preferably below 2.2 wt%, more preferably below 1.9 wt%.

[0039] This invention does not impose particular limitations on the preparation process of the furan polyester composition; either batch polymerization or continuous polymerization can be used. Specifically, 2,5-furan dicarboxylic acid or its esterified derivative can be reacted with an aliphatic diol through esterification or transesterification to obtain a small molecule polymer. This small molecule polymer is then subjected to polycondensation to obtain the furan-based polyester composition. During the preparation process, a germanium-based catalyst and a phosphite antioxidant are added, preferably after the addition of the germanium-based catalyst. According to conventional furan polyester composition preparation methods, appropriate reaction temperatures and pressures can be selected during the esterification / transesterification and polycondensation stages. Depending on the desired function, co-catalysts such as manganese acetate, magnesium acetate, and calcium acetate, or functional additives such as matting agents, colorants, and flame retardants can also be added to the furan polyester composition.

[0040] The germanium-based catalyst is generally prepared as a solution of aliphatic diol (i.e., catalyst solution) before being added. This catalyst solution can be added at any stage of the furan polyester composition preparation process (i.e., any stage before the end of the polymerization reaction), preferably during the esterification or transesterification reaction stage, or before vacuuming begins after the small molecule polymer is transferred to the polymerization reactor. Specifically, the esterification or transesterification reaction stage can be the stage after the raw materials are added to the esterification or transesterification reactor and before reaching the end temperature of the esterification or transesterification reaction, or the stage after the esterification or transesterification reaction is completed and before transfer to the polymerization reactor.

[0041] The phosphite antioxidant can be added at any stage of the preparation process of the furan polyester composition (i.e., any stage before the end of the polymerization reaction), preferably during the esterification or transesterification reaction stage, or before vacuuming begins after the small molecule polymer is transferred to the polymerization reactor. Specifically, the esterification or transesterification reaction stage can be the stage after the raw materials are added to the esterification or transesterification reactor and before reaching the end temperature of the esterification or transesterification reaction, or the stage after reaching the end temperature of the esterification or transesterification reaction and before the end of the esterification or transesterification reaction, or the stage after the end of the esterification or transesterification reaction and before transferring to the polymerization reactor.

[0042] To ensure the reaction rate of the furan polyester composition, it is preferable to add a germanium-based catalyst followed by a phosphite antioxidant.

[0043] Through the above preferred technical solutions, the furan polyester composition of the present invention has good color, heat resistance and crystallinity. The heat resistance index %BB after heat treatment at 290°C for 6 hours under nitrogen conditions is below 0.60, and it can be used in the preparation of fibers, films, engineering plastics and the like.

[0044] The methods for measuring and evaluating the various indicators of this invention are as follows:

[0045] (1) Intrinsic viscosity (IV)

[0046] Dissolve 0.8g of furan polyester composition chips in 10ml of o-chlorophenol solution. Test the Ts using a fully automatic viscosity tester (manufactured by Japan Lihe Co., Ltd., model VTS-032UC) at a water bath temperature of 150±0.2℃. Then calculate the intrinsic viscosity of the furan polyester composition according to IV=0.0246·Ts+0.269 (take the average value after three tests).

[0047] (2) Dimer content (diethylene glycol, dipropylene glycol, dipentanediol, dihexanediol, etc.)

[0048] Weigh 0.5 g of the furan polyester composition sample and add it to 1.25 ml of solvent (internal standard 1,6-hexanediol / solvent ethanolamine 5 mg / 1.25 ml). Heat to dissolve, add 10 ml of methanol, and then cool in an ultrasonic bath until ammonium salts precipitate. Finally, add 8 g of terephthalic acid for neutralization, and filter with filter paper to obtain a clear liquid. Inject 2 ml of the clear liquid into a Shimadzu GC-14B gas chromatograph (GC) for analysis, and determine the composition and content of the dimer by the internal standard method.

[0049] (3) Heat resistance (%BB)

[0050] The IV of the furan polyester composition chips measured according to test method (1) is calculated based on η = -0.703 + 3.21 × IV - 2.13 × IV 2 +0.527×IV3 The limiting viscosity η0 of the untreated slice was calculated.

[0051] Take 8g of furan polyester composition slices and place them in a test tube. Purge the test tube with nitrogen gas and heat at 290°C for 6 hours. Then test the IV of the treated slices according to test method (1). t Then according to η t = -0.703 + 3.21 × IV t -2.13×IV t 2 +0.527×IV t 3 Calculate the limiting viscosity η of the processed slices. t。 Finally, according to the formula %BB = 0.27 × (1 / η) t 4 / 3 -1 / η0 4 / 3 Calculate the %BB of the furan polyester composition chips.

[0052] (4) Determination of germanium and phosphorus content in furan polyester composition

[0053] Take 5g of furan polyester composition and perform fluorescence X-ray spectral analysis using a Rigaku ZSXprimusll+ fluorescence spectrometer. Based on the standard element spectrum, the instrument automatically determines whether the sample contains germanium and phosphorus elements, and automatically calculates the content of germanium and phosphorus elements (the average value is taken after two tests).

[0054] (5) Hue b value

[0055] The test was conducted according to the national standard GB / T 14190-1993 (the average value was taken after three tests).

[0056] (6) Determination of phosphite antioxidants

[0057] Tested according to national standard GB / T 16631-2008.

[0058] (7) Crystallinity

[0059] Weigh 10 mg of the furan polyester composition sample and test its thermal properties using a TA DSC25 under the following conditions. Obtain a graph with time on the x-axis and heat flux on the y-axis, as shown in Figure 1 of this application specification. The time at the start of the crystallization peak A is recorded as T0. The peak area S corresponding to the crystallization peak is read using the DSC25. A Reaching 0.5S A The time corresponding to the hour is denoted as T. 1， Half-crystallization time (sec) = T1 - T0. The shorter the half-crystallization time, the better the crystallinity.

[0060] DSC test conditions: First, heat to the melting point +30℃ at 30℃ / min, then cool down to 30℃ at 200℃ / min, and finally heat up to 160℃ at 200℃ / min and hold for 180min.

[0061] (8) Filter pressure difference ΔPa

[0062] The test was conducted using a small-scale filtration testing machine (Chubu Chemical Machinery Works, CN25-05 model) for pressure testing. The furan polyester composition was melted at a temperature 25°C higher than its melting point and passed through a 5μm pore size filter at a feed rate of 10 g / min. The pressure before the filter at 30 minutes after the start of feeding was recorded as the initial pressure Pa1. The final pressure Pa2 was recorded 3 hours after the initial pressure. The pressure rise over 3 hours was ΔPa = Pa2 - Pa1. A smaller ΔPa indicates a lower amount of foreign matter in the furan polyester composition.

[0063] Example 1

[0064] At a temperature of 220°C, 103 parts by weight of furan dicarboxylic acid (FDCA), 50 parts by weight of ethylene glycol (EG), antioxidant A at 0.0647 wt% of phosphorus relative to the weight of the furan ring, and germanium dioxide at 500 ppm of germanium relative to the furan polyester composition were added to an esterification reactor. The esterification reaction was carried out under normal pressure. When the esterification reaction was completed, the temperature inside the esterification reactor was 230°C. Water was fractionated to obtain a small molecule polymer.

[0065] The obtained small-molecule polymer was subjected to a reduced pressure and increased temperature at 230°C to initiate a polycondensation reaction. The temperature was increased from 230°C to 270°C while the pressure was reduced to 25 Pa. The final temperature and pressure were reached after 90 minutes, and the polymer was then discharged after a further reaction period to reach the target viscosity (IV). During discharge, the polymer was in the form of uniform strips, which were cooled in a water bath and then granulated to obtain furan polyester composition chips. The specific formulation and physical properties are shown in Table 1.

[0066] Examples 2-21

[0067] The preparation process is the same as in Example 1, and the specific formulation and properties are shown in Tables 1 and 2.

[0068] Comparative Example 1

[0069] The antioxidant was changed to phosphoric acid, and the rest was the same as in Example 1. The specific formulation and properties are shown in Table 2.

[0070] Because it does not use phosphite antioxidants, its heat resistance, color, and crystallinity are too poor.

[0071] Comparative Example 2

[0072] The catalyst type was changed to tetrabutyl titanate, and the rest was the same as in Example 1. The specific formulation and properties are shown in Table 2.

[0073] Because it does not use a germanium-based catalyst, its heat resistance, color, and crystallinity are too poor.

[0074]

[0075]

Claims

1. A furan polyester composition consisting essentially of 2,5-furan dicarboxylic acid structural units and aliphatic dihydric alcohol structural units, characterized in that: The polyester composition contains germanium and a phosphite antioxidant.

2. The furan polyester composition according to claim 1, characterized by: The phosphite antioxidant is one or more of the antioxidants represented by Formula 1, Formula 2, or Formula 3, ， In Equation 1, R 1 R 2 They are phenyl, alkyl with 2 to 30 carbon atoms, or aromatic alkyl with 7 to 30 carbon atoms, respectively; in Formula 2, R 3 It is a phenyl, biphenyl, alkylene group with 2 to 30 carbon atoms, or aromatic alkyl group with 7 to 12 carbon atoms, R 4 ~R 7 They are phenyl, alkyl groups having 2 to 30 carbon atoms, or aromatic alkyl groups having 7 to 12 carbon atoms, respectively; in formula 3, R 8 ~R 10 They are alkyl groups with 2 to 30 carbon atoms, respectively.

3. The furan polyester composition according to claim 1 or 2, characterized by: The germanium is present in an amount of 5 to 1000 ppm based on the total amount of the furan polyester composition.

4. The furan polyester composition according to claim 3, characterized by: The germanium is present in an amount of 5 to 700 ppm based on the total amount of the furan polyester composition.

5. The furan polyester composition according to claim 1 or 2, characterized by: The total content of the phosphite antioxidant is 0.0010 to 0.5000 wt% based on the total weight of the furan ring.

6. The furan polyester composition according to claim 5, characterized by: The total content of the phosphite antioxidant is 0.0010 to 0.1000 wt% based on the total weight of the furan ring.

7. The furan polyester composition according to any one of claims 1 or 2, characterized by: The molar ratio of the phosphite antioxidant to the germanium is 0.10 or more based on the phosphorus element.

8. The furan polyester composition according to any one of claims 1 or 2, characterized by: The aliphatic diol structural unit is one or more of an ethylene glycol structural unit, a propylene glycol structural unit, a butanediol structural unit, and a pentanediol structural unit.

9. The furan polyester composition according to any one of claims 1 or 2, characterized by: The content of the dimer of the aliphatic diol is 2.2 wt% or less.

10. Use of the furan polyester composition of claim 1 in fibers, films, and engineering plastics.

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