A furan polyester composition and its application

Abstract

This invention discloses a furan polyester composition, which is mainly composed of 2,5-furan dicarboxylic acid structural units and aliphatic diol structural units. The furan polyester composition contains germanium and antioxidants with specific structures. The furan polyester composition also exhibits good color tone and heat resistance, and can be used in fibers, films, engineering plastics, etc.

Description

Technical Field

[0001] This invention relates to a furan polyester composition, specifically, to a furan polyester composition with good heat resistance and good color. 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, in the production of high-performance polymers, 2,5-furandicarboxylic acid is a powerful substitute for many aromatic dicarboxylic acids.

[0003] Chinese patent CN116003762A discloses a 2,5-furandicarboxylic acid-based polyester and its preparation method. Using dimethyl 2,5-furandicarboxylic acid, a diol, a catalyst, and a stabilizer as raw materials, a negative pressure transesterification polymerization process with a synergistic catalyst is employed to prepare a 2,5-furandicarboxylic acid-based polyester with good heat resistance, mechanical properties, and color. The catalyst comprises a complex system of metal acetate salts and germanium, and the stabilizer is a phosphorus-based compound including phenyl phosphite. However, the carboxyl group on the 2,5-furandicarboxylic acid has poor thermal stability, and ring-opening occurs during high-temperature polymerization, forming free radicals, resulting in a darker polyester color. Furthermore, the steric hindrance of the phenyl phosphite stabilizer makes coordination with the furan group difficult, hindering its antioxidant effect. Additionally, the compatibility between the phenyl phosphite stabilizer and the furan polyester composition is poor, easily forming foreign matter. Summary of the Invention

[0004] The purpose of this invention is to provide a furan polyester composition that has both good color and heat resistance, and this furan polyester composition can be used in fibers, films, engineering plastics, etc.

[0005] The technical solution of this invention:

[0006] A furan polyester composition, mainly composed of 2,5-furandicarboxylic acid structural units and aliphatic diol structural units, wherein the furan polyester composition contains germanium and antioxidants as shown in Formula 1 and / or Formula 2, wherein the total molar ratio of the total amount of -OH groups of the antioxidants as shown in Formula 1 and Formula 2 to the germanium is 0.8 to 200.00.

[0007]

[0008] In Equation 1, R 1 R 2 They are hydrogen atoms or alkyl groups, respectively, R3 It is alkyl, phenylalkyl, ester or none, M 1 For alkyl, phenyl, or ester groups, m is an integer from 1 to 4; in Formula 2, R 4 It is alkyl, phenylalkyl, ester or none, M 2 R is an alkyl, phenyl, or ester group. 5 ~R 8 They are either hydrogen atoms or alkyl groups, and n is an integer from 1 to 4.

[0009] The germanium element preferably accounts for 5 to 300 ppm of the total amount of the furan polyester composition.

[0010] The ratio of the total weight of the antioxidants as shown in Formulas 1 and 2 to the total weight of the furan rings is preferably 0.04 to 0.40 wt%.

[0011] The molar ratio of the total amount of -OH groups in the antioxidants shown in Formulas 1 and 2 to the germanium element is preferably 0.80 to 100.00.

[0012] The terminal carboxyl group COOH content of the furan polyester composition is preferably below 40.0 eq / t, and the diethylene glycol content is preferably below 4.0 wt%.

[0013] This invention improves the dispersion and catalytic efficiency of germanium-based catalysts in polyester reactions by using a combination of germanium catalysts and oxidants with specific structures, thereby obtaining furan polyester compositions with good color and heat resistance, which are suitable for fibers, films, engineering plastics and other fields. Detailed Implementation

[0014] 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).

[0015] In the existing technology, when preparing furan polyester, antimony-based and titanium-based catalysts are often used. Antimony catalysts will reduce the color of furan polyester composition, contaminate spinning components, and generate foreign matter during production and product manufacturing. Titanium-based catalysts have high catalytic activity for side reactions while catalyzing the reaction, resulting in furan polyester composition with severe yellowing and poor heat resistance.

[0016] The germanium-based catalyst used in the furan polyester composition of the present invention has good catalytic activity, is milder in its activity against side reactions compared to other catalysts, and causes virtually no pollution to the spinning components. The resulting furan polyester composition has good color and heat resistance.

[0017] The germanium-based catalyst refers to a substance that exhibits catalytic activity during the furan polyester reaction, such as germanium dioxide, germanium monoxide, germanium disulfide, germanium monosulfide, germanium selenide, germanium chloride, germanium fluoride, tetraethyl germanium, n-butyl germanium, and isobutyl germanium. Considering factors such as product stability and cost, the germanium-based catalyst of this invention is preferably germanium dioxide.

[0018] 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 10–600 ppm of the total amount of the furan polyester composition, 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 5–300 ppm of the total amount of the furan polyester composition.

[0019] Because the furan ring in the furan polyester composition is prone to decomposition at high temperatures, generating free radicals, these free radicals will turn yellow upon contact with oxygen, resulting in a deterioration in the color of the furan polyester composition. Furthermore, the furan polyester composition will undergo degradation reactions upon heating, mainly manifested in ester group breakage and molecular weight reduction, leading to a decrease in the strength and heat resistance of the furan polyester composition.

[0020] Therefore, in addition to avoiding the influence of other catalysts on the color of the final furan polyester composition by selecting a germanium-based catalyst, another important means of this invention is to select a suitable antioxidant to achieve the effect of suppressing the deterioration of the color and heat resistance of the furan polyester composition.

[0021] The antioxidants described in this invention are antioxidants as shown in Formula 1 and / or Formula 2. These antioxidants can coordinate with the furan ring, inhibiting its decomposition. For free radicals generated by decomposition, the antioxidants 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. In addition, the antioxidants can also coordinate with germanium-based catalysts, inhibiting the side reaction activity of the germanium-based catalysts, reducing the degradation of the furan polyester composition, and improving the heat resistance of the furan polyester composition.

[0022]

[0023] In Equation 1, R 1 R 2 They are hydrogen atoms or alkyl groups, respectively, R 3 It is alkyl, phenylalkyl, ester or none, M 1 R is an alkyl, phenyl, or ester group, where m is an integer from 1 to 4; in Formula 2, R 4 It is alkyl, phenylalkyl, ester or none, M 2 R is an alkyl, phenyl, or ester group. 5 ~R 8 They are either hydrogen atoms or alkyl groups, and n is an integer from 1 to 4.

[0024] R in Equation 1 1 R 2 The -OH groups can be distributed on the benzene ring, R. 3 Or M 1 The adjacent, intermediate, or opposite positions corresponding to the connected positions.

[0025] The antioxidants used in this invention can be specifically listed as follows: In Formula 1, R 1 and R 2 All are dimethylethyl and located at the meta position, the -OH group at the para position, and R... 3 Methyl propionate group (-(CH2)2COOCH2-), M 1 Antioxidant A is a carbon atom with m=4; in Formula 2, R 5 and R 7 For hydrogen atoms, R 6 and R 8 dimethyl ethyl, R 4 Ethyl (≡CCH3, where ≡ indicates that three hydrogen atoms are substituted), M 2 Antioxidant B is 1,2-ethylene acetate (-CH2COO(CH2)2OOCCH2-); in Formula 1, R 1 It is methyl and located in the meta position, R 2 It is dimethylethyl and located at the meta position, the -OH group is located at the para position, and R 3It is dimethyl propionate ethanol ester group (-(CH2)2COOCH2C(CH3)2-), M 1 The antioxidant C is 2,4,8,10-tetraoxaspiro[5.5]undecyl, with m=2; in Formula 1, R 1 and R 2 All are dimethylethyl and located at the meta position, the -OH group at the para position, and have no R. 3 M 1 The antioxidant D is methyl and m is 1; in Formula 1, R 1 It is methyl and located in the meta position, R 2 It is a dimethyl ethyl group located at the meta position, with the -OH group at the para position, and no R. 3 M 1 The antioxidant E is a butyl group (=CH(CH2)2CH3, where = indicates that two hydrogen atoms are substituted) with m=2; in Formula 1, R 1 It is methyl and located in the meta position, R 2 It is a dimethyl ethyl group located at the meta position, and the -OH group is located at the ortho position and close to R. 2 No R 3 M 1 Methylene group, antioxidant F with m=2; in Formula 1, R 1 and R 2 All are methyl groups located at the meta position, with the -OH group at the para position and no R group. 3 M 1 The antioxidant G is a methine with m=3; in Formula 1, R 1 and R 2 All are dimethylethyl and located at the meta position, the -OH group at the para position, and have no R. 3 M 1 An antioxidant H is 2,4,6-trimethylphenyl with m = 3; in Formula 1, R 1 and R 2 All are methyl groups located at the meta position, with the -OH group at the para position and no R group. 3 M 1 Antioxidant I, etc., is a 1,3,5-trisubstituted phenyl group with m=3.

[0026] When using antioxidants, one of the antioxidants shown in Formula 1 and Formula 2 can be used alone, or two or three can be used simultaneously. The amount of antioxidant in the furan polyester composition of the present invention refers to the total content of antioxidants shown in Formula 1 and Formula 2.

[0027] The antioxidants described in Formulas 1 and 2 of this invention function by coordinating with germanium-based catalysts to inhibit the side reaction activity of germanium-based catalysts, reduce the degradation of furan polyester compositions, and improve the heat resistance of furan polyester compositions. Through research on a series of factors, including the magnitude of the side reaction activity of germanium-based catalysts, the degradation reaction characteristics of furan polyester compositions, and the effect of coordination between the catalyst and the germanium-based catalyst on the polymerization catalytic activity of the germanium-based catalyst, the molar ratio of the total amount of -OH groups in the antioxidants described in Formulas 1 and 2 to the germanium element is 0.80–200.00. The total amount of -OH groups in the antioxidants described in Formulas 1 and 2 of this invention refers to the total amount of -OH groups (phenolic hydroxyl groups) on the benzene ring of the antioxidants described in Formulas 1 and 2. If the molar ratio of -OH groups to germanium in the antioxidants shown in Formulas 1 and 2 is less than 0.80, the coordination between the -OH groups and the germanium-based catalyst is insufficient, which is insufficient to suppress the side reaction activity of the germanium-based catalyst, resulting in poor heat resistance of the obtained furan polyester composition. If the molar ratio of -OH groups to germanium in the antioxidants shown in Formulas 1 and 2 is greater than 200.00, the amount of germanium catalyst added is too small, resulting in insufficient polymerization reactivity; or the amount of antioxidant added is too large, forming foreign matter in the furan polyester composition, which will precipitate in subsequent processes such as spinning or film formation, requiring equipment cleaning. To further improve the heat resistance and anti-yellowing effect of the furan polyester composition, the molar ratio of the total amount of -OH groups in the antioxidants shown in Formulas 1 and 2 to the germanium element is preferably 0.80 to 100.00.

[0028] As described above, the antioxidant also inhibits the decomposition of furan rings and captures free radicals. Therefore, by studying the decomposition probability of furan rings and the efficiency of the antioxidant on furan rings and free radicals, this invention provides that the ratio of the total weight of the antioxidants shown in Formulas 1 and 2 to the total weight of furan rings is preferably 0.04 to 0.40 wt%, where the total weight of furan rings is the total weight of all furan rings in the furan polyester composition. Within the preferred weight ratio range, the antioxidant can exert its full effect. If the ratio of the total weight of the antioxidants shown in Formulas 1 and 2 to the total weight of furan rings is too small, the color tone of the resulting furan polyester composition tends to decrease; if the ratio of the total weight of the antioxidants shown in Formulas 1 and 2 to the total weight of furan rings is too large, with the absence of furan rings that can inhibit decomposition and free radicals to capture, the excess antioxidant in the resulting furan polyester composition tends to increase. This excess antioxidant forms foreign matter in the furan polyester composition and will precipitate during processes such as spinning or film making, requiring frequent equipment cleaning.

[0029] The present invention does not impose any particular limitation on the selection of the preparation process for furan-based polyesters; it can be either batch polymerization or continuous polymerization. One example is as follows: a small molecule polymer is obtained by esterification or transesterification of 2,5-furandicarboxylic acid or its esterified derivative with an aliphatic diol. This small molecule polymer is then polymerized to obtain a furan-based polyester composition. During the preparation process, one or more antioxidants as shown in Formula 1 and / or Formula 2, as well as a germanium-based catalyst, are added. According to conventional furan-based polyester 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, matting agents such as titanium dioxide, colorants such as blue dyes, and flame retardants such as phosphorus-based flame retardants can also be added to the furan-based polyester.

[0030] The germanium-based catalyst is generally prepared as a solution of aliphatic diol before being added. The catalyst solution can be added at any stage of the polyester reaction, specifically at the esterification or transesterification stage, at the end of the esterification or transesterification stage, before the polycondensation reaction, or at any stage from the start to the end of the polycondensation reaction, preferably before the polycondensation reaction.

[0031] To suppress the decomposition of the furan ring, the antioxidants shown in Formulas 1 and 2 are preferably added before the polycondensation reaction, and more preferably added at the initial stage of the esterification or transesterification reaction.

[0032] Through the above preferred technical solutions, the polyester composition of the present invention has good color and heat resistance. The heat resistance index %BB after heat treatment at 290℃ for 6 hours under nitrogen conditions is less than 0.55. The terminal carboxyl group COOH of the furan polyester composition is less than 40.0 eq / t, and the diethylene glycol content is less than 4.0 wt%. It can be applied to the fields of fibers, films, engineering plastics, etc.

[0033] The methods for measuring and evaluating the various indicators of this invention are as follows:

[0034] (1) Intrinsic viscosity (IV)

[0035] Dissolve 0.8g of furan polyester composition chips in 10ml of o-chlorophenol solution. Test the viscosity (Ts) using an automated viscosity tester (manufactured by Nippon Rikaisha, model VTS-032UC) at a water bath temperature of 150±0.2℃. Then calculate the intrinsic viscosity of the furan polyester composition according to the following formula (average value after three tests).

[0036] IV = 0.0246·Ts + 0.269

[0037] (2) Carboxyl group content (COOH)

[0038] The determination was performed using an optical titration method. The furan polyester composition chips were dissolved in a mixture of o-methylphenol and chloroform (weight ratio 70:30), and bromothymol blue was used as an indicator. Then, the titration was performed using an AOUA COUNTER B-1700 instrument with a 0.05 mol / L potassium hydroxide ethanol solution. The instrument was (average value was taken after two tests).

[0039] (3) DEG content

[0040] Take 0.5g of furan polyester composition slices and add them to 1.25ml of solvent (internal standard 1,6-hexanediol / solvent ethanolamine 5mg / 1.25ml). Heat until the furan polyester composition slices dissolve, then add 10ml of methanol and cool in an ultrasonic bath until ammonium salts precipitate. Finally, add 8g of terephthalic acid for neutralization, and filter with filter paper to obtain a clear liquid. Inject 2ml of the clear liquid into a Shimadzu GC-14B gas chromatograph (GC) for analysis (take the average value after two tests).

[0041] (4) Heat resistance (%BB)

[0042] 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×IV 3 Calculate the limiting viscosity η0 of the untreated slice. 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℃ for 6 hours. Test the IV of the treated slices according to test method (1). t Then calculate η according to the aforementioned formula. 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.

[0043] (5) Determination of germanium content in furan polyester composition

[0044] 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 automatically calculates the germanium content (the average value is taken after two tests).

[0045] (6) Hue b value

[0046] Measured according to national standard GB / T 14190-1993 (average value after three tests).

[0047] (7) Determination of antioxidants

[0048] Using the liquid chromatography internal standard method, 1.0000 g of polyester composition was accurately weighed, and 20 mL of hexafluoroisopropanol was added. The mixture was heated to 25 °C until the polyester composition was completely dissolved. After cooling, an internal standard solution of terphenyl / dichloromethane was added, followed by the addition of methanol solution to precipitate the polyester. After centrifugation, the solution was used to determine the antioxidant activity using the internal standard method (the average value was taken after three tests).

[0049] Column: XDBC 18 (5μm), 250mm × 4.6mm,

[0050] Detector: Diode array detector

[0051] Mobile phase: methanol

[0052] Mobile phase flow rate: 1.3 ml / min

[0053] Injection volume: 10 μL

[0054] Detection wavelength: 275nm.

[0055] (8) Method for determining the content of phenolic hydroxyl (-OH) groups in furan polyester compositions

[0056] A certain amount of alkali-soluble slices were dissolved in trifluoroacetic acid and subjected to H-NMR analysis. The molar content of phenolic hydroxyl (-OH) units in the furan polyester composition was calculated based on the peak area of ​​the characteristic peak.

[0057] Example 1

[0058] At a temperature of 220°C, 156 parts by weight of furanyl dicarboxylic acid (FDCA), 71.3 parts by weight of ethylene glycol (EG), 0.067 wt% antioxidant A relative to the weight of furanyl dicarboxylic acid, and 12.5 ppm germanium dioxide 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.

[0059] 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 polyester composition chips. Specific formulations and properties are shown in Tables 1 and 2.

[0060] Examples 2-19

[0061] The preparation process is the same as in Example 1, and the specific formulation and properties are shown in Tables 1 and 2.

[0062] Comparative Example 1

[0063] The catalyst was changed to tetrabutyl titanate. The titanium element in the furan polyester composition accounted for 15 ppm of the furan polyester composition, and the content of antioxidant A accounted for 0.110 wt% of the total weight of the furan rings. The rest was the same as in Example 1. The specific formulation and physical properties are shown in Table 2.

[0064] Because tetrabutyl titanate was used as a catalyst, it had high catalytic activity for side reactions and a high b-value, resulting in severe yellowing and poor heat resistance of the obtained furan polyester composition.

[0065] Comparative Example 2

[0066] No antioxidants were added; otherwise, it was the same as in Example 3. The specific formulation and properties are shown in Table 2.

[0067] Because no antioxidants were used, the resulting furan polyester composition had poor heat resistance, a high b-value, and yellowish chips.

[0068] Comparative Example 3

[0069] The total weight of antioxidant A was changed to 0.80 wt% of the total weight of furan rings, and the molar ratio of the total amount of -OH groups of antioxidant A to the germanium element was changed to 246.00. The rest was the same as in Example 14. The specific formulation and physical properties are shown in Table 2.

[0070] Because the total amount of -OH groups in antioxidant A is too high in molar ratio to germanium, the resulting furan polyester composition has poor heat resistance, a high b-value, and yellowish chips.

[0071]

[0072]

Claims

1. A furan polyester composition, mainly composed of 2,5-furan dicarboxylic acid structural units and aliphatic diol structural units, characterized in that: The furan polyester composition contains germanium and antioxidants as shown in Formula 1 and / or Formula 2, wherein the total molar ratio of the -OH groups of the antioxidants as shown in Formula 1 and Formula 2 to the germanium is 0.80 to 200.

00. R 1 , R 2 are each a hydrogen atom or an alkyl group, R 3 is an alkyl group, a phenylalkyl group, an ester group or nothing, M 1 is an alkyl group, a phenyl group, an ester group, and m is an integer of 1 to 4; in formula 2, R 4 is an alkyl group, a phenylalkyl group, an ester group or nothing, M 2 is an alkyl group, a phenyl group or an ester group, R 5 to R 8 are each a hydrogen atom or an alkyl group, and n is an integer of 1 to 4.

2. The furan polyester composition according to claim 1, characterized in that: The germanium element accounts for 5 to 300 ppm of the total amount of the furan polyester composition.

3. The furan polyester composition according to claim 1, characterized in that: The ratio of the total weight of the antioxidants as shown in Formulas 1 and 2 to the total weight of the furan rings is 0.04 to 0.40 wt%.

4. The furan polyester composition according to claim 1, characterized in that: The total amount of -OH groups in the antioxidants shown in Formulas 1 and 2, to the molar ratio of germanium, is 0.80 to 100.

00.

5. The furan polyester composition according to claim 1, characterized in that: The furan polyester composition has a terminal carboxyl group COOH content of less than 40.0 eq / t and a diethylene glycol content of less than 4.0 wt%.

6. The use of the furan polyester composition of claim 1 in fibers, films, and engineering plastics.

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