Polycyclic bio-based monomer toughened pbt copolyester and method of making

Abstract

The application belongs to the field of polymer synthesis, and particularly relates to a modified PBT copolyester, and a preparation method of the modified PBT copolyester. x BT y copolyester. The modified PBT copolyester is prepared by using a bio-based monomer synthesized from a renewable resource through a green and environmentally-friendly synthesis method and an easy-to-operate synthesis process. The obtained copolyester has high toughness, and the defects of pure PBT are compensated, so that the copolyester has a wider application.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and relates to the utilization of renewable resources and the field of green synthesis technology. Specifically, it relates to a polycyclic bio-based monomer toughened PBT copolyester and its preparation method. Background Technology

[0002] Polybutylene terephthalate (PBT) is a milky white, translucent to opaque, semi-crystalline thermoplastic polyester. Due to its excellent properties such as high heat resistance, aging resistance, solvent resistance, high resilience, and ease of processing, it is widely used in electronics, automobiles, and machinery. However, PBT also suffers from poor flexibility when used alone, which limits its application range. In existing technologies, researchers have employed various methods to improve the flexibility of PBT, including: 1) chemical modification, using methylene diisocyanate, epoxy functional groups, etc., as chain extenders to extend the chain of PBT; 2) physical modification, using ethylene-acrylate copolymers, glycidyl methacrylate-grafted polyolefin elastomers, etc., to blend with PBT.

[0003] However, many problems exist. For example, the raw materials used in chemical modification are derived from petroleum resources and are highly toxic, posing a long-term and significant threat to the natural environment. Physical modification often faces challenges such as poor compatibility between PBT and the modified filler, leading to a significant decline in the material's thermal properties and reduced service life. Furthermore, the modified fillers used are also petroleum-based materials. How to improve the toughness of PBT polyester materials using raw materials derived from green biomass is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a type of polycyclic bio-based monomer-toughened PBT copolyester and its preparation method. This preparation method features mild reaction conditions, high yield, a simple and easy-to-operate process, and the monomer is derived from biomass, making it environmentally friendly and promising for industrial production.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides a type of polycyclic bio-based monomer-toughened PBT copolyester, comprising repeating units of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate)butylene as shown in formula (a) and repeating units of butylene terephthalate as shown in formula (b); named poly(N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate)butylene-co-butylene terephthalate), wherein the number-average molecular weight of the PBT copolyester is not less than 10000 g / mol;

[0007]

[0008] Furthermore, in the PBT copolyester, the N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene diester repeating units account for 5%-60% by mole fraction; the remainder are butylene terephthalate repeating structural units.

[0009] Furthermore, in the PBT copolyester, the N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene diester repeating units account for 10%-30% by mole fraction; the remainder are butylene terephthalate repeating structural units.

[0010] Further, the poly(N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene-co-butylene terephthalate) is abbreviated as PBF. x BT y Where F, T, and B represent terephthalic acid, N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate methyl ester), and 1,4-butanediol, respectively; x ranges from greater than 5 to less than 60, and y ranges from greater than 40 to less than 95, representing the molar proportions of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate methyl ester) butylene ester unit and butylene terephthalate unit in the copolyester multiplied by 100.

[0011] Furthermore, the specific steps include:

[0012] The polycyclic bio-based monomer N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester), terephthalic acid, and 1,4-butanediol were added to a closed reactor, and a catalyst was added. The transesterification reaction, pre-condensation reaction, and final condensation reaction were carried out in sequence to obtain the PBT copolyester.

[0013] Further, the alkyd molar ratio is 1.2-3:1, which is the ratio of the molar amount of 1,4-butanediol to the sum of the molar amounts of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester) and terephthalic acid.

[0014] Furthermore, the alkyd molar ratio is 2:1.

[0015] Further, the catalyst is tetrabutyl titanate, and the amount of catalyst added is 0.05% to 0.4% of the total molar amount of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester) and terephthalic acid. Preferably, it is 0.1% to 0.3%.

[0016] Furthermore, the catalyst is tetrabutyl titanate diluted with toluene, and the volume ratio of toluene to tetrabutyl titanate is 3:1.

[0017] Furthermore, the temperature of the transesterification reaction is 180-230°C, and the transesterification reaction time is 8-10 h; more preferably 220°C.

[0018] Furthermore, the vacuum degree of the pre-condensation reaction is 5 kPa-20 kPa; the reaction temperature is 220-240°C; and the reaction time is 0.5-1 h; more preferably, the vacuum degree of the pre-condensation reaction is 12 kPa.

[0019] Furthermore, the polycondensation reaction is carried out under a vacuum of less than or equal to 60 Pa, at a temperature of 240 °C, and for a duration of 2–4 h.

[0020] Furthermore, the transesterification reaction is carried out under nitrogen protection; and the final polycondensation reaction is carried out under high vacuum.

[0021] Thirdly, this invention discloses the use of a type of polycyclic bio-based monomer, N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester), for toughening PBT polyester.

[0022] The beneficial effects of this invention are as follows:

[0023] 1) In this invention, bio-based monomers are used to modify polyester. The monomers are entirely derived from biomass, and the raw materials are renewable, which can effectively alleviate the oil shortage crisis and environmental pollution.

[0024] 2) The method for synthesizing polyester in this invention is green and environmentally friendly, with a simple and easy-to-operate synthesis process, high synthesis yield, and the potential for large-scale production.

[0025] 3) The copolyester material provided by this invention has adjustable properties and can easily achieve diversification of structure and function. The addition of bio-based monomers can obtain high-toughness modified PBT polyester, which broadens its application field. Attached Figure Description

[0026] Figure 1 The hydrogen nuclear magnetic resonance spectrum of Example 4;

[0027] Figure 2 This is the DSC melt curve diagram of Example 4;

[0028] Figure 3 This is the DSC melt curve of Example 1;

[0029] Figure 4 This is a tensile-stress-strain curve diagram of Example 1;

[0030] Figure 5 This is a tensile-stress-strain curve diagram of Example 2. Detailed Implementation

[0031] The following embodiments are specific illustrations of the present invention. 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. Any non-essential adjustments and improvements made to the present invention by those skilled in the art are within the scope of protection of the present invention.

[0032] In the following embodiments, unless otherwise specified, all raw materials are basically commercially available or prepared by conventional methods in the art.

[0033] In the following embodiments, nuclear magnetic resonance spectroscopy 1 H-NMR was performed using Bruker Ascend. TM The instrument was used to measure at room temperature, 500 MHz, CDCl3, C2DF3O2.

[0034] In the following examples, thermal transformation analysis was performed using a TA Q2000 differential scanning calorimeter at a heating rate of 10 °C / min under a nitrogen atmosphere, with a temperature range of -70 to 270 °C.

[0035] In the following examples, the mechanical property analysis was performed using an IBTC-300SL miniature in-situ mechanical testing machine. The tensile rate of the specimens was set to 6 mm / min at room temperature.

[0036] In the examples, N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene-co-butylene terephthalate is abbreviated as PBF. x BT y Where F, T, and B represent terephthalic acid, N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate methyl ester), and 1,4-butanediol, respectively; x and y are values ​​greater than 0 and less than 100, representing the molar percentages of the N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate methyl ester) butylene ester block and the butylene terephthalate block in the copolyester, respectively. (e.g., PBF in Example 1) 10 BT 90 This indicates that the PBF block accounts for 10% of the molar percentage in the PBT copolyester.

[0037] Example 1

[0038] PBF 10 BT 90 Preparation of copolyesters:

[0039] 1) PBF was prepared by melt polycondensation of monomers N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate), terephthalic acid, and 1,4-butanediol. 10 BT90 Copolyester with an alkyd molar ratio of 2:1;

[0040] 2) Weigh 0.38g of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester), 1.50g of terephthalic acid and 1.80g of 1,4-butanediol according to the designed alcohol-acid molar ratio, place them in a well-sealed round-bottom flask, add 0.008g of tetrabutyl titanate catalyst, and react for 8h at a transesterification temperature of 220℃ under a nitrogen atmosphere.

[0041] 3) Increase the temperature to 240℃, remove the nitrogen protection, and pre-polymerize at this temperature under a vacuum of 12kPa for 0.5h;

[0042] 4) Adjust the vacuum to 60 Pa, keep the temperature at 240 °C, and carry out a polycondensation reaction for 2 hours to obtain the copolyester.

[0043] Example 2

[0044] PBF 30 BT 70 Preparation of copolyesters:

[0045] 1) PBF was prepared by melt polycondensation of monomers N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester), terephthalic acid, and 1,4-butanediol. 30 BT 70 Copolyester with an alkyd molar ratio of 2:1;

[0046] 2) Weigh 1.14g of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester), 1.16g of terephthalic acid and 1.80g of 1,4-butanediol according to the designed alcohol-acid molar ratio, place them in a well-sealed round-bottom flask, add 0.01g of tetrabutyl titanate catalyst dropwise, and react for 9.3h at a transesterification temperature of 220℃ under a nitrogen atmosphere.

[0047] 3) Increase the temperature to 240℃, remove the nitrogen protection, and pre-polymerize at this temperature under a vacuum of 12kPa for 0.5h;

[0048] 4) Adjust the vacuum to 60 Pa, keep the temperature at 240 °C, and carry out a polycondensation reaction for 2 hours to obtain the copolyester.

[0049] Example 3

[0050] PBF 40 BT 60 Preparation of copolyesters:

[0051] 1) PBF was prepared by melt polycondensation of monomers N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate), terephthalic acid, and 1,4-butanediol. 40 BT 60 Copolyester with an alkyd molar ratio of 2:1;

[0052] 2) Weigh 1.51g of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester), 1.00g of terephthalic acid and 1.80g of 1,4-butanediol according to the designed alcohol-acid molar ratio, place them in a well-sealed round-bottom flask, add 0.01g of tetrabutyl titanate catalyst dropwise, and react for 9.2h at a transesterification temperature of 220℃ under a nitrogen atmosphere.

[0053] 3) Increase the temperature to 240℃, remove the nitrogen protection, and pre-polymerize at this temperature under a vacuum of 12kPa for 0.5h;

[0054] 4) Adjust the vacuum to 60 Pa, keep the temperature at 240 °C, and carry out a polycondensation reaction for 2.3 h to obtain the copolyester.

[0055] Example 4

[0056] PBF 50 BT 50 Preparation of copolyesters:

[0057] 1) PBF was prepared by melt polycondensation of monomers N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate), terephthalic acid, and 1,4-butanediol. 50 BT 50 Copolyester with an alkyd molar ratio of 2:1;

[0058] 2) Weigh 1.90g of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester), 0.83g of terephthalic acid and 1.80g of 1,4-butanediol according to the designed alcohol-acid molar ratio, place them in a well-sealed round-bottom flask, add 0.01g of tetrabutyl titanate catalyst dropwise, and react for 9.2h at a transesterification temperature of 220℃ under a nitrogen atmosphere;

[0059] 3) Increase the temperature to 240℃, remove the nitrogen protection, and pre-polymerize at this temperature under a vacuum of 12kPa for 0.5h;

[0060] 4) Adjust the vacuum to 60 Pa, keep the temperature at 240 °C, and carry out a polycondensation reaction for 2 hours to obtain the copolyester.

[0061] Determining PBF by nuclear magnetic resonance 50 BT 50 The chemical structure of copolyester.

[0062] Figure 1 PBF was prepared by melt polycondensation of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate), terephthalic acid, and 1,4-butanediol. 50 BT 50 copolyester 1 The H-NMR values ​​are shown in the figure. The peaks at δ 1.96–1.69 ppm (g) and δ 4.48–4.33 ppm (f) are attributed to the -CH2- proton in 1,4-butanediol; the peak at δ 2.69 ppm (c) is attributed to the -CH2- proton adjacent to the nitrogen atom on the pyrrolidone ring; the peak at δ 3.23 ppm (b) is attributed to the -CH- proton on the pyrrolidone ring; the peak at δ 3.56 ppm (a) is attributed to the -CH2- proton adjacent to the carbonyl group on the pyrrolidone ring; the peaks at δ 4.19–4.13 ppm (d) and δ 6.18 ppm (e) are attributed to the -CH2- and -C=CH- protons on 2,5-bis(aminomethyl)furan, respectively; and the peak at δ 8.08 ppm (h) is attributed to the proton in the benzene ring of terephthalic acid.

[0063] In combination with the above 1 H-NMR analysis can prove PBF 50 BT 50 The synthesis of the copolyester was successful.

[0064] Example 5

[0065] PBF 60 BT 40 Preparation of copolyesters:

[0066] 1) PBF was prepared by melt polycondensation of monomers N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate), terephthalic acid, and 1,4-butanediol. 60 BT 40 Copolyester with an alkyd molar ratio of 2:1;

[0067] 2) Weigh 2.27g of N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester), 0.66g of terephthalic acid and 1.80g of 1,4-butanediol according to the designed alcohol-acid molar ratio, place them in a well-sealed round-bottom flask, add 0.01g of tetrabutyl titanate catalyst dropwise, and react for 8h at a transesterification temperature of 220℃ under a nitrogen atmosphere.

[0068] 3) Increase the temperature to 240℃, remove the nitrogen protection, and pre-polymerize at this temperature under a vacuum of 12kPa for 0.5h;

[0069] 4) Adjust the vacuum to 60 Pa, keep the temperature at 240 °C, and carry out a polycondensation reaction for 2.5 h to obtain the copolyester.

[0070] Test Example 1

[0071] Example 4: Copolyester DSC Test:

[0072] 1) Weigh 5-10 mg of the copolyester prepared in Example 4 and place it in a differential scanning calorimeter to test the melt curve;

[0073] 2) Set the program to “heat up-isothermal-cool down-isothermal-heat up”, with a temperature test range of -70 to 270℃ and a heating and cooling rate of 10℃ / min, and obtain the melting curve.

[0074] Figure 2 The figure shows the DSC melt curve of the copolyester in Example 4. The glass transition temperature (Tg) of this copolyester can be observed from the graph. g The temperature was 36.8℃.

[0075] Test Example 2

[0076] Example 1: Copolyester DSC Test:

[0077] 1) Weigh 5-10 mg of the copolyester prepared in Example 1 and place it in a differential scanning calorimeter to test the melt curve;

[0078] 2) Set the program to “heat up-isothermal-cool down-isothermal-heat up”, with a temperature test range of -70 to 270℃ and a heating and cooling rate of 10℃ / min, and obtain the melting curve.

[0079] Figure 3 The figure shows the DSC melt curve of the copolyester in Example 1. The melting point (T) of this copolyester can be observed in the figure. m The temperature is 200.2℃.

[0080] Test Example 3

[0081] PBF 10 BT 90 Copolyester tensile properties test:

[0082] 1) The copolyester obtained in Example 1 was processed into dumbbell-shaped strips by compression molding and placed in a micro in-situ mechanical testing machine to test its tensile properties.

[0083] 2) At room temperature, the tensile rate of the sample was set to 6 mm / min, and the PBF was tested. 10 BT 90 The tensile strength, tensile modulus, and elongation at break of copolyester and PBT were determined, and tensile-stress-strain curves were obtained.

[0084] Figure 4 For PBT and PBF 10 BT 90 The tensile-stress-strain curve of copolyester shows that the elongation at break of PBT is 15%, and the PBF... 10 BT 90 The copolyester has a breaking elongation of 96%, and the addition of 10 mol% N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylic acid methyl ester) can effectively improve the toughness of PBT.

[0085] Test Example 4

[0086] PBF 30 BT 70 Copolyester tensile properties test:

[0087] 1) The copolyester obtained in Example 2 was processed into dumbbell-shaped strips by compression molding and placed in a micro in-situ mechanical testing machine to test its tensile properties.

[0088] 2) At room temperature, the tensile rate of the sample was set to 6 mm / min, and the PBF was tested. 30 BT 70 The tensile strength, tensile modulus, and elongation at break of copolyester and PBT were determined, and tensile-stress-strain curves were obtained.

[0089] Figure 5 For PBT and PBF 30 BT 70 The tensile-stress-strain curve of copolyester shows that the elongation at break of PBT is 15%, and the PBF... 10 BT 90 The copolyester exhibits an elongation at break of 189%, and the addition of 30 mol% N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate) can further enhance the toughness of PBT. Therefore, the N,N'-2,5-di(methyl)furan-bis(pyrrolidone-4-carboxylate) bio-based monomer can effectively toughen PBT.

Claims

1. A polycyclic bio-based monomer-toughened PBT copolyester, characterized in that, The PBT copolyester comprises N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene diester as shown in formula (a) and butylene terephthalate butylene diester as shown in formula (b). （a） （b） The PBT copolyester is named poly(N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene-co-butylene terephthalate).

2. The polycyclic bio-based monomer-toughened PBT copolyester according to claim 1, characterized in that, In the PBT copolyester, the N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylate) butylene diester repeating units and butylene terephthalate repeating structural units account for 5%-60% of the total molar amount, with the sum of the molar amounts of N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylate) butylene diester repeating structural units being 100%; the remainder is butylene terephthalate repeating structural units.

3. The polycyclic bio-based monomer-toughened PBT copolyester according to claim 1, characterized in that, In the PBT copolyester, the N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene diester repeating units account for 10%-30% by mole fraction; the remainder are butylene terephthalate repeating structural units.

4. A method for preparing a polycyclic bio-based monomer-toughened PBT copolyester as described in any one of claims 1-3, characterized in that, The PBT copolyester is obtained by bulk polymerization of N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester) with terephthalic acid and 1,4-butanediol.

5. The preparation method according to claim 4, characterized in that, Specifically, the following steps are included: N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester), terephthalic acid, and 1,4-butanediol were added to a closed reactor, and a catalyst was added. The transesterification reaction, pre-condensation polymerization, and final condensation polymerization were carried out in sequence to obtain the PBT copolyester.

6. The preparation method according to claim 4, characterized in that, The molar ratio of the 1,4-butanediol to the sum of the molar amounts of N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester) and terephthalic acid is 1.2-3:

1.

7. The preparation method according to claim 5, characterized in that, The catalyst is tetrabutyl titanate, and the amount of catalyst added is 0.05% to 0.4% of the total molar amount of N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester) and terephthalic acid.

8. The preparation method according to claim 5, characterized in that, The transesterification reaction was carried out at a temperature of 180-230℃ for 8-10 hours. The pre-condensation reaction is carried out under a vacuum of 5 kPa to 20 kPa; the reaction temperature is 220 to 240 °C; and the reaction time is 0.5 to 1 h.

9. The preparation method according to claim 5, characterized in that, The polycondensation reaction is carried out under a vacuum of less than or equal to 60 Pa, at a temperature of 240 °C, and for a duration of 2 to 4 hours.

10. Use of the polycyclic bio-based monomer N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester), characterized in that, The N,N'-2,5-dimethylfuran-bis(pyrrolidone-4-carboxylic acid methyl ester) is used for toughening PBT polyester.

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