Method for preparing polyester

Abstract

This application describes a method for producing nano-TiO in a monoclinic state by using a raw material containing a dibasic acid and a diol. 2 That is, TiO 2 (B) contacting a catalyst with the polyester to sequentially carry out an esterification reaction and a polycondensation reaction to prepare the polyester. The method can efficiently catalyze the synthesis of the polyester and effectively avoid the yellowing of the color of the polyester, and can also effectively prevent the yellowing of the color of the polyester by using nano-TiO 2 (B) Nano-TiO is polymerized in situ in polyester. 2 By utilizing the structure of (B), the structure and performance of the polyester matrix can be controlled, and the mechanical properties, thermal properties and barrier properties of the polyester can be effectively improved.

Description

[Technical Field]

[0001] The present application relates to a method for preparing polyesters and is in the technical field of polyester materials. [Background technology]

[0002] Catalysts are an important factor affecting the color of polyesters. The color of polyesters is primarily due to the coordination of metal ions in the catalyst with groups in the polyester during the polymerization process, forming chromophoric groups with the metal ions as color centers. For example, manganese, cobalt, and germanium catalysts all produce darker polyester colors. However, traditional high-efficiency titanium-based catalysts are prone to decomposition and aggregation in the presence of water, which can affect the polymerization process and lead to inconsistent color and yellowing of polyesters. Catalytic activity is also an important factor affecting polyester color. Under harsh reaction conditions, catalysts with low activity are prone to decarboxylation of the monomer dibasic acid, generating small molecule by-products, resulting in darker polyester colors. Lead, antimony, and tin catalysts are highly active, but they are heavy metals themselves and can pose unpredictable risks to humans and the entire biological system. Summary of the Invention

[0003] The technical problem to be solved by this application is to develop a method for preparing polyester using nano-TiO2(B) as a catalyst to synthesize high-performance polyester, which can solve the problem of yellowing of polyester color and improve the mechanical, thermal and barrier properties of polyester. [Means for solving the problem]

[0004] According to one aspect of the present application, a catalyst for polyester synthesis and a method for preparing polyester that achieves nanocomposite integration are provided.

[0005] The method for preparing the polyester comprises: the polyester is prepared by contacting a raw material containing a dibasic acid and a diol with a catalyst to carry out an esterification reaction and a polycondensation reaction; The catalyst is nano-TiO2(B).

[0006] Optionally, the dibasic acid is selected from at least one of furandicarboxylic acid, terephthalic acid.

[0007] Optionally, the diol is C 2~4 selected from diols, Preferably, the diol is ethylene glycol, 1,3-propanediol , 1,4-butanediol.

[0008] Optionally, the nano-TiO2 (B) is selected from one of a zero-dimensional nanomaterial, a one-dimensional nanomaterial, a two-dimensional nanomaterial, and a three-dimensional nanomaterial; the zero-dimensional nanomaterial is a nanoparticle; the one-dimensional nanomaterial is a nanowire; the two-dimensional nanomaterial is a nanosheet; The three-dimensional nanomaterial is a nanoporous sphere.

[0009] Alternatively, the molar ratio of the diol to the dibasic acid is 1.4 to 3.0:1; Further alternatively, the upper limit of the molar ratio of diol to diacid may be independently selected from 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, and 3.0, and the lower limit of the molar ratio of diol to diacid may be independently selected from 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9.

[0010] Alternatively, the amount of the catalyst used is 0.5 to 10‰ moles of the dibasic acid; Further alternatively, the upper limit of the amount of TiO2(B) catalyst used may be independently selected from 7.5‰, 8‰, 8.5‰, 9‰, 9.5‰, and 10‰, and the lower limit of the amount of TiO2(B) catalyst used may be independently selected from 0.5‰, 2.5‰, 3‰, 3.5‰, 4‰, 4.5‰, and 5‰.

[0011] Optionally, the esterification reaction occurs under inert atmospheric conditions.

[0012] Optionally, the inert atmosphere is a nitrogen atmosphere.

[0013] Alternatively, the esterification reaction temperature is 190 to 220° C., and the esterification reaction time is 1 to 4 hours.

[0014] Further alternatively, the esterification reaction temperature may be independently selected from 190°C, 200°C, 210°C, and 220°C; Alternatively, the polycondensation reaction temperature is 220 to 250°C; Further alternatively, the polycondensation reaction temperature may be independently selected from 220°C, 230°C, 240°C, and 250°C; Optionally, the polycondensation reaction time is 1 to 8 hours.

[0015] Further alternatively, the polycondensation reaction time may be independently selected from 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, and 8 h.

[0016] According to another aspect of the present application, there is provided a polyester prepared according to the above method, The polyester has a color value b≦11.2; The intrinsic viscosity is 0.92 to 1.36 dL / g, The tensile strength is 62 to 120 MPa. The elongation at break is 27 to 266%. The oxygen barrier coefficient is 0.5 x 10 -13 ~8.2×10 -12 is. [Effects of the Invention]

[0017] The beneficial effects that this application can produce include:

[0018] (1) This application develops a new method for synthesizing polyester using co-catalysis, which can improve the added value of the polyester industry. The nano-TiO2(B) catalyst can efficiently catalyze the synthesis of polyester and effectively prevent the yellowing of polyester. The nano-TiO2(B) can be polymerized in situ in the polyester, and the structure of the nano-TiO2(B) can be used to control the structure and performance of the polyester matrix.

[0019] (2) The high catalytic activity of nano-TiO2(B) reduces the reactive properties of the substrate molecules, lowers the temperature required for polyester synthesis, and avoids the occurrence of side reactions (decarboxylation of the monomer dibasic acid), thereby solving the problem of yellowing in polyester synthesis using conventional polyester catalysts. At the same time, nano-TiO2(B) not only acts as a catalyst during the polymerization process, but also disperses in situ into the polyester matrix, utilizing the catalyst structure to effectively improve the mechanical properties and barrier performance of polyester.

[0020] (3) By utilizing the high activity of the TiO2(B) catalyst due to the large number of Lewis acid sites on its surface, the polymerization reaction activation energy can be reduced, thereby lowering the polymerization reaction temperature and avoiding the occurrence of side reactions (decarboxylation of the monomer dibasic acid), thereby improving the color problem of polyester. In addition, during the polymerization process, nano-TiO2(B) not only acts as a catalyst, but also disperses in situ in the polyester matrix, utilizing the appropriate interfacial structure formed between nano-TiO2(B) and the polyester molecular chain, thereby improving the performance of polyester. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is an electron microscope photograph of zero-dimensional TiO2(B) nanoparticles in Examples 1 and 10. [Figure 2] 1 is an electron microscope photograph of one-dimensional TiO2(B) nanowires in Example 2. [Figure 3]1 shows electron microscope photographs of two-dimensional TiO2(B) nanosheets in Examples 3, 5 to 9, and 11 to 14. [Figure 4] 1 is an electron microscope photograph of three-dimensional TiO2(B) nanoporous spheres in Example 4. [Figure 5] 1 is a cross-sectional electron microscope photograph of the PEF / TiO2(B) nanocomposite polyester in Example 1. [Figure 6] 1 is a cross-sectional electron microscope photograph of the PTF / TiO2(B) nanocomposite polyester in Example 14. [Figure 7] 1 is a cross-sectional electron microscope photograph of the PBF / TiO2(B) nanocomposite polyester in Example 13. [Figure 8] 1 is a cross-sectional electron microscope photograph of the PET / TiO2(B) nanocomposite polyester in Example 5. [Figure 9] 1 is a cross-sectional electron microscope photograph of the PTT / TiO2(B) nanocomposite polyester in Example 12. [Figure 10] 1 is a cross-sectional electron microscope photograph of the PBT / TiO2(B) nanocomposite polyester in Example 11. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present application will be described in detail below with reference to examples, but the present application is not limited to these examples.

[0023] In order to explain the present invention more clearly, the present invention will be further described below in connection with preferred embodiments. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive, and therefore does not limit the scope of protection of the present invention.

[0024] Unless otherwise specified, the raw materials and catalysts in the examples herein are purchased commercially.

[0025] Here, furandicarboxylic acid was prepared according to the method in Example 1 of Patent CN201810442696.1, terephthalic acid was purchased from Yinuokai Co., Ltd., and other raw materials were purchased from Sinopharm Group.

[0026] The nano-TiO2 (B) catalyst employed in the examples of this application is prepared by the following preparation method:

[0027] (1) Preparation method of TiO2(B) nanoparticles: By liquid-phase chemical precipitation, 5 mL of TiCl4 was used as a titanium source, and 200 mL of a mixed solvent of water and ethylene glycol (EG) (where the volume ratio of EG to water was 10:1) was heated to reflux to hydrolyze TiCl4. The reaction was allowed to proceed for 0.2 hours, followed by centrifugation and washing with absolute ethanol to prepare TiO2(B) nanoparticles.

[0028] (2) Preparation method of TiO2(B) nanowires: By chemical precipitation and hydrothermal methods, 2 mL of tetrabutyl titanate was hydrolyzed in 20 mL of a mixed solution of water and ethanol (where the volume ratio of water to ethanol is 1:1) to obtain 20 nm particles. Then, the particles were hydrothermally reacted at 160 °C for 4 h under strong alkaline conditions with 20 mL of 10 mol / L KOH, and then the particles were dissolved in 0.1 M dilute nitric acid to obtain TiO2(B) nanowires. + The titanium dioxide nanowires are then calcined in a muffle furnace at 350 °C for 2 h to obtain one-dimensional TiO (B) nanowires.

[0029] (3) Preparation method of TiO2(B) nanosheets: By liquid-phase chemical precipitation, 5 mL of TiCl4 was used as the titanium source, and 200 mL of a mixed solution of ethylene glycol and water (the volume ratio of EG to water was 10:1) was used as the solvent. EG was used as the structure-directing agent, and the mixture was heated to reflux for 2 hours to hydrolyze TiCl4. The structure-directing agent EG bonded with the c-axis of the TiO2 unit cell, inhibiting its growth along the c-axis. The unit cell then grew into two-dimensional TiO2(B) nanosheets along the a- and b-axes.

[0030] (4) Preparation of TiO2(B) nanoporous spheres: Liquid-phase chemical precipitation, hydrothermal method, and high-temperature calcination. 5 mL of tetrabutyl titanate was alcoholyzed in 100 mL of ethanol, and 1.5 mL of long-chain oleylamine was used as a structural directing agent to obtain titanium alkoxide nanospheres assembled with nanoparticles. The nanospheres were then hydrothermally reacted in 20 mL of 10 mol / L strong alkaline NaOH solution at 180 °C for 6 hours to obtain sodium titanate. The resulting solution was then substituted with 0.1 M dilute HCl (H + DeNa + (substitution) to obtain metatitanic acid, which is then calcined at 350 °C for 4 h to obtain TiO(B) nanoporous spheres assembled with nanowires.

[0031] The examples used in this application used a 3nm color difference meter (NR200) ​​to measure color and a Chuo-Ubbelohde viscometer (IVS100) to measure intrinsic viscosity. Viscosity and color measurements were both performed using the test methods specified in GB / T 14190-2008. Tensile strength and elongation at break were measured using an Instron electronic universal material testing machine (Instron-1121) in accordance with the requirements of ASTM D638. Tensile tests were performed at 25°C using the Instron-1121 testing machine at a tensile speed of 5 mm / min. Dumbbell-shaped samples measuring 3.18 mm wide and 3.2 mm thick were prepared by injection molding using an injection molding machine, and the tensile strength and elongation at break of the samples were obtained. The oxygen permeability was measured using a Labthink oxygen permeability test system (VAC-V2), and the test method was in accordance with GB / T 1038-2000. [Example]

[0032] Using 0.1 mol of furandicarboxylic acid and 0.16 mol of ethylene glycol as raw materials (alkyd molar ratio 1.6), TiO2(B) nanoparticles were used as catalyst. The amount of TiO2(B) nanoparticles (details of the electron microscope photograph, Figure 1) was 5‰ mol of furandicarboxylic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 240°C for 2 hours. The reaction was then stopped. The resulting product, polyethylene 2,5-furandicarboxylate (PEF), was tested for color and viscosity. The obtained sample was then crushed and subjected to injection molding, and mechanical and barrier properties tests were performed. The results are shown in Table 1. [Example]

[0033] Using 0.1 mol of furandicarboxylic acid and 0.16 mol of ethylene glycol as raw materials (alkyd molar ratio 1.6), TiO2(B) nanowires were used as catalyst. The amount of TiO2(B) nanowires used was 5‰ mol of furandicarboxylic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 240°C for 2 hours. The reaction was then stopped. The obtained product, polyethylene 2,5-furandicarboxylate (PEF), was subjected to color and viscosity tests. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier properties tests. The results are shown in Table 1. [Example]

[0034] Using 0.1 mol of furandicarboxylic acid and 0.16 mol of ethylene glycol as raw materials (alkyd molar ratio 1.6), TiO2(B) nanosheets were used as catalyst. The amount of TiO2(B) nanosheets (details of the electron microscope photograph, Figure 3) used was 5‰ mol of furandicarboxylic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 240°C for 2 hours. The reaction was then stopped. The obtained product, polyethylene 2,5-furandicarboxylate, was subjected to color and viscosity tests. The obtained sample was then crushed and subjected to injection molding, and mechanical and barrier properties tests. The results are shown in Table 1. [Example]

[0035] Using 0.1 mol of furandicarboxylic acid and 0.16 mol of ethylene glycol as raw materials (alkyd molar ratio 1.6), TiO2(B) nanoporous spheres were used as catalyst. The amount of TiO2(B) nanoporous spheres (details of the electron microscope image are shown in Figure 4) was 5‰ mol of furandicarboxylic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 240°C for 2 hours. The reaction was then stopped. The resulting product, polyethylene 2,5-furandicarboxylate (PEF), was subjected to color and viscosity tests. The obtained sample was then crushed and injection molded, and mechanical and barrier properties were tested. The results are shown in Table 1. [Example]

[0036] Using 0.1 mol of terephthalic acid and 0.25 mol of ethylene glycol as raw materials (alkyd molar ratio 2.5), TiO2(B) nanosheets were used as a catalyst. The amount of TiO2(B) nanosheets (details of the electron microscope photograph, Figure 3) used was 5‰ mol of terephthalic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 250°C for 2 hours to terminate the reaction. The obtained product, polyethylene terephthalate (PET), was subjected to color and viscosity tests. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier performance tests. The results are shown in Table 1. [Example]

[0037] Using 0.1 mol of furandicarboxylic acid and 0.16 mol of ethylene glycol as raw materials (alkyd molar ratio 1.6), TiO2(B) nanosheets were used as a catalyst. The amount of TiO2(B) nanosheets used was 2.5‰ mol of furandicarboxylic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 240°C for 2 hours. The reaction was then stopped. The obtained product, polyethylene 2,5-furandicarboxylate (PEF), was subjected to color and viscosity tests. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier properties tests. The results are shown in Table 1. [Example]

[0038] Using 0.1 mol of furandicarboxylic acid and 0.16 mol of ethylene glycol as raw materials (alkyd molar ratio 1.6), TiO2(B) nanosheets were used as a catalyst. The amount of TiO2(B) nanosheets (details of the electron microscope photograph, Figure 3) used was 1% molar of furandicarboxylic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 240°C for 2 hours to terminate the reaction. The obtained product, polyethylene 2,5-furandicarboxylate (PEF), was subjected to color and viscosity tests. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier performance tests. The results are shown in Table 1. [Example]

[0039] Using 0.1 mol of terephthalic acid and 0.3 mol of ethylene glycol as raw materials (alkyd molar ratio 3), TiO2(B) nanosheets were used as a catalyst. The amount of TiO2(B) nanosheets (details of the electron microscope photograph are shown in Figure 3) was 1% by mole of terephthalic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour each, and then polycondensation reaction was carried out at 250°C for 2 hours to terminate the reaction. The obtained product, polyethylene terephthalate (PET), was subjected to color and viscosity tests. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier performance tests. The results are shown in Table 1. [Example]

[0040] Using 0.1 mol of terephthalic acid and 0.25 mol of ethylene glycol as raw materials (alkyd molar ratio 2.5), TiO2(B) nanosheets were used as a catalyst. The amount of TiO2(B) nanosheets (details of the electron microscope photograph are shown in Figure 3) was 5‰ mol of terephthalic acid. Under nitrogen protection, the esterification reaction was carried out, followed by esterification at 190°C, 200°C, 210°C, and 220°C for 4 hours, and polycondensation at 240°C for 2 hours, after which the reaction was stopped. The obtained product, polyethylene terephthalate (PET), was subjected to color and viscosity tests. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier performance tests. The results are shown in Table 1. [Example]

[0041] Using 0.1 mol of terephthalic acid and 0.3 mol of ethylene glycol as raw materials (alkyd molar ratio 3), TiO2(B) nanoparticles were used as a catalyst. The amount of TiO2(B) nanoparticles (details of the electron microscope photograph in Figure 1) used was 5‰ mol of terephthalic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour each, and then polycondensation was carried out at 250°C for 2 hours to terminate the reaction. The resulting polyethylene terephthalate (PET) was tested for color and viscosity. The obtained sample was then crushed and injection molded, and mechanical and barrier properties were tested. The results are shown in Table 1. [Example]

[0042] Using 0.1 mol of terephthalic acid and 0.24 mol of 1,4-butanediol as raw materials (alkyd molar ratio 2.4), TiO2(B) nanosheets were used as a catalyst. The amount of TiO2(B) nanosheets (details of the electron microscope photograph are shown in Figure 3) was 5‰ mol of terephthalic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 4 hours, and then polycondensation reaction was carried out at 240°C for 2 hours to terminate the reaction. The obtained product, polybutylene terephthalate (PBT), was subjected to color and viscosity tests. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier performance tests. The results are shown in Table 1. [Example]

[0043] 0.1 mol of terephthalic acid and 0.14 mol of 1,3-propanediolUsing the above as the raw material (alkyd molar ratio is 1.4), TiO2(B) nanosheets as a catalyst, the amount of TiO2(B) nanosheets used (details of the electron microscope photograph are shown in Figure 3) was 0.5‰ mol of terephthalic acid, and under the protection of nitrogen, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour each, and then the polycondensation reaction was carried out at 240°C for 2 hours to terminate the reaction. The obtained product, polytrimethylene terephthalate (PTT), was tested for color and viscosity. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier performance tests. The results are shown in Table 1. [Example]

[0044] Using 0.1 mol of furandicarboxylic acid and 0.25 mol of 1,4-butanediol as raw materials (alkyd molar ratio 2.5), TiO2(B) nanosheets were used as catalyst. The amount of TiO2(B) nanosheets (details of the electron microscope photograph, Figure 3) used was 5‰ mol of furandicarboxylic acid. Under nitrogen protection, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 240°C for 2 hours. The reaction was then stopped. The obtained product, polybutylene 2,5-furandicarboxylate (PBF), was subjected to color and viscosity tests. The obtained sample was then crushed and injection molded, and mechanical and barrier properties were tested. The results are shown in Table 1. [Example]

[0045] 0.1 mol of furandicarboxylic acid and 0.16 mol of 1,3-propanediol Using the above as the raw material (alkyd molar ratio of 1.6), TiO2(B) nanosheets were used as a catalyst. The amount of TiO2(B) nanosheets (details of the electron microscope photograph are shown in Figure 3) was 5‰ moles of furandicarboxylic acid. Under the protection of nitrogen, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour each, and then the polycondensation reaction was stopped at 240°C for 2 hours. The obtained product, polytrimethylene 2,5-furandicarboxylate PTF, was tested for color and viscosity. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier performance tests. The results are shown in Table 1.

[0046] Comparative Example 1 Using 0.1 mol of furandicarboxylic acid and 0.16 mol of ethylene glycol as raw materials (alkyd molar ratio 1.6), tetrabutyl titanate was used as a catalyst. The amount of tetrabutyl titanate used was 5‰ mol of furandicarboxylic acid. Under the protection of nitrogen, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 250°C for 2 hours, after which the reaction was stopped. The obtained product, polyethylene 2,5-furandicarboxylate (PEF), was tested for color and viscosity. The obtained sample was then crushed and subjected to injection molding and mechanical and barrier properties tests. The results are shown in Table 1.

[0047] Comparative Example 2 Using 0.1 mol of terephthalic acid and 0.16 mol of ethylene glycol as raw materials (alkyd molar ratio 2.5), tetrabutyl titanate was used as a catalyst. The amount of tetrabutyl titanate used was 5‰ mol of terephthalic acid. Under the protection of nitrogen, the esterification reaction was carried out at 190°C, 200°C, 210°C, and 220°C for 1 hour, respectively, and then polycondensation reaction was carried out at 250°C for 2 hours, and the reaction was stopped. The obtained product, polyethylene terephthalate (PET), was tested for color and viscosity. The obtained sample was crushed and then injection molded and subjected to mechanical and barrier performance tests. The results are shown in Table 1.

[0048] [Table 1] TIFF0007785797000002.tif60158

[0049] In conventional nanocomposite processes, the addition of small amounts of nanomaterials affects the polymer structure, which in turn affects the polymer's mechanical properties. Common toughening mechanisms in polymer nanocomposites include debonding and pull-out, crack deflection, crack pinning, and crack bridging. The nano-TiO2 (B) catalyst does not form a very strong interfacial bond with the polymer matrix during polyester polymerization, but has adequate weak interfacial strength. Under external force loading, the nanomaterials are prone to "cavitation" phenomena, such as debonding, crack deflection, and nanomaterial pull-out within the polymer matrix. The interface serves to block crack propagation and consumes additional energy, increasing the total fracture energy and toughening the material while also improving other performance features. As can be seen from Examples 1 to 4, Examples 6 to 7, and Comparative Example 1, when nano-TiO2 (B) is used as a catalyst, the tensile strength and elongation at break of the obtained polyethylene 2,5-furandicarboxylate (PEF) are both superior to those of the PEF prepared when tetrabutyl titanate is used as a catalyst. In other words, when nano-TiO2 (B) is used as a catalyst, the toughness of the obtained polyethylene 2,5-furandicarboxylate (PEF) is higher.

[0050] As can be seen from Examples 1 to 4, Examples 6 and 7, and Comparative Example 1, under the same polyester synthesis temperature conditions, the viscosity of the polyester obtained in Comparative Example 1 was lower than the viscosity of the polyester when TiO2(B) was used as a catalyst, and the color b values ​​of the polyester obtained in Comparative Example 1 were all higher than the b values ​​of the polyesters prepared in the Examples of the present invention. The oxygen permeability of the polyester obtained in Comparative Example 1 was also higher than the oxygen permeability of the polyesters prepared in the Examples of the present invention. In other words, by using TiO2(B) as a catalyst to prepare polyester in the present invention, polyesters with higher viscosity, lower b values, and better barrier properties can be obtained at the same synthesis temperature.

[0051] As can be seen from Examples 5, 8 to 10, and Comparative Example 2, under the same polyester synthesis temperature conditions, the viscosity of the polyester obtained in Comparative Example 2 was lower than the viscosity of the polyester when TiO2(B) was used as a catalyst, the color b values ​​of the polyester obtained in Comparative Example 2 were all higher than the b values ​​of the polyesters prepared in the Examples of the present invention, and the oxygen permeability coefficients of the polyesters obtained in Comparative Example 2 were all higher than the oxygen permeability coefficients of the polyesters prepared in the Examples of the present invention. In other words, by using TiO2(B) as a catalyst to prepare polyesters in the present invention, polyesters with higher viscosity, lower b values, and better barrier properties can be obtained at the same synthesis temperature.

[0052] As can be seen from Examples 5, 8 to 10 and Comparative Example 2, when nano-TiO2 (B) is used as a catalyst, the tensile strength and elongation at break of the obtained polyester (PET) are both superior to those of the PET prepared when tetrabutyl titanate is used as a catalyst, that is, when nano-TiO2 (B) is used as a catalyst, the obtained PET has higher toughness.

[0053] Figures 5 to 10 are cross-sectional electron microscope photographs of the prepared composite polyester. As can be seen from Figures 5 to 10, there is no obvious aggregation phenomenon in the composite polyester matrix, and the catalyst is dispersed in situ in the polyester matrix with high dispersibility.

[0054] The above are merely some examples of the present application, and are not intended to limit the present application in any way. The present application has been disclosed as a preferred embodiment as above, but this is not intended to limit the present application. Those skilled in the art will be able to make some changes or modifications using the technical content disclosed above within the scope of the technical solution of the present application, which are all equivalent to equivalent embodiments, and all fall within the scope of the technical solution.

Claims

1. 1. A method for preparing a polyester comprising the steps of: the polyester is prepared by contacting a raw material containing a dibasic acid and a diol with a catalyst and sequentially carrying out an esterification reaction and a polycondensation reaction; The catalyst is nano TiO ２ (B) the dibasic acid is selected from at least one of furandicarboxylic acid and terephthalic acid; the diol is selected from at least one of ethylene glycol, 1,3-propanediol, and 1,4-butanediol; The polyester has a color b≦11.2, an intrinsic viscosity of 0.92 to 1.36 dL / g, a tensile strength of 62 to 120 MPa, an oxygen barrier coefficient of 0.5×10 −13 to 8.2×10 −12 , and an elongation at break of 27 to 266%; A method characterized by:

2. The nano TiO ２ (B) is selected from one of a zero-dimensional nanomaterial, a one-dimensional nanomaterial, a two-dimensional nanomaterial, and a three-dimensional nanomaterial; the zero-dimensional nanomaterial is a nanoparticle; the one-dimensional nanomaterial is a nanowire; the two-dimensional nanomaterial is a nanosheet; The three-dimensional nanomaterial is a nanoporous sphere.

2. The method of claim 1 .

3. the molar ratio of the diol to the dibasic acid is 1.4 to 3.0:1; The amount of the catalyst used is 0.5 to 10‰ moles of the dibasic acid.

2. The method of claim 1 .

4. The esterification reaction occurs under inert atmospheric conditions.

2. The method of claim 1 .

5. The inert atmosphere is a nitrogen atmosphere.

5. The method of claim 4.

6. The esterification reaction temperature is 190 to 220°C, and the esterification reaction time is 1 to 4 hours.

2. The method of claim 1 .

7. the polycondensation reaction temperature is 220 to 250°C, The polycondensation reaction time is 1 to 8 hours.

2. The method of claim 1 .

8. A polyester prepared by the process of any one of claims 1 to 7.

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