Novel organic titanium polyester catalyst as well as preparation method and application thereof

Abstract

The invention discloses a novel organic titanium polyester catalyst as well as a preparation method and application thereof, relates to the technical field of synthesis of polyester catalysts, and solves the problems of poor water resistance and thermal stability, many side reactions and the like of the existing polyester catalyst. According to the catalyst, Ti ions serve as an active center, titanate and heterocyclic benzyl alcohol with a reaction site and a complexing site are subjected to reaction-chelation, benzyl alcohol reaction replaces an original alkoxy chain, and heteroatoms in heteroaromatic rings play a role in coordination chelation. Through reaction-chelation of the ligands, the catalyst has excellent hydrolysis resistance and high catalytic activity, and side reactions are effectively inhibited. The catalyst is simple to prepare and suitable for industrial production; the polyester material synthesized by catalytic polymerization of the catalyst has high molecular weight, excellent hue and ideal terminal carboxyl group value.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester catalysts. Specifically, it relates to a novel organic titanium-based polyester catalyst, its preparation method and application. Background Art

[0002] The polyester industry maintains continuous growth globally. As the technical core of the polyester industry, polyester catalysts directly affect the reaction rate, selectivity, and molecular weight control of polyester synthesis, thus significantly influencing the final properties and applications of polyester materials. The main polyester catalysts on the current market include antimony-based, titanium-based, and germanium-based catalysts. However, antimony catalysts have potential toxicity and environmental impacts, and germanium-based catalysts have the drawback of high price costs. Against this background, titanium-based catalysts have become an ideal catalyst choice due to their high efficiency and environmental friendliness.

[0003] Titanium-based polyester catalysts are generally divided into two categories: organic titanium and inorganic titanium. Among organic titanium catalysts, titanates are the most widely used, such as tetrabutyl titanate, tetrapropyl titanate, and isopropyl titanate, etc., which have the characteristics of high catalytic activity and fast reaction rate. However, they also have disadvantages such as easy hydrolysis, poor thermal stability, and many side reactions, often resulting in yellowing of polyester products or a decline in quality. Inorganic titanium catalysts, such as titanium dioxide modified type, titanium-silicon type, etc., although their stability has been improved to some extent, they have deficiencies in solubility and dispersibility, affecting the catalytic efficiency.

[0004] In current research, improving the thermal stability, hydrolysis resistance, and controlling the occurrence of side reactions of titanium-based catalysts have become technical difficulties. Summary of the Invention

[0005] To solve the above problems, the present application provides a novel organic titanium-based polyester catalyst and its preparation method to overcome the disadvantages of existing titanium-based catalysts such as poor thermal stability, easy hydrolysis, and many side reactions. Through the reaction-chelation of titanate with heterocyclic benzyl alcohol, the reaction is carried out under solvent-free and vacuum conditions to introduce a chelating group to form a stable chelate, making the catalyst have excellent water resistance, thermal stability, and high catalytic activity, thereby improving the quality of polyester products.

[0006] The first aspect of the present invention provides a novel organic titanium-based polyester catalyst. The novel organic titanium-based polyester catalyst includes a catalyst main body, and the structural formula of the catalyst main body is shown as follows:

[0007]

[0008] Wherein, both R1 and R2 are alkyl chains, and X is a heteroatom.

[0009] Optionally, R1 and R2 are selected from alkyl groups having 1 to 6 carbon atoms, and R1 and R2 may be the same group or different groups. Optionally, X is one of N, O or S atoms.

[0010] Optionally, the heterocycle has 5 to 8 carbon atoms.

[0011] Optionally, the mass content of titanium element is 1 to 10%.

[0012] In this application, the catalyst main body takes Ti atoms as the active center, and reacts and chelates a titanate with a heterocyclic benzyl alcohol having both reaction sites and complexing sites. Among them, the benzyl alcohol group replaces the original alkoxy chain, and the heteroatom in the heterocycle plays a role of coordination and chelation. Through the reaction-chelating of the ligand, the catalyst has excellent hydrolysis resistance and high catalytic activity, effectively inhibiting the occurrence of side reactions.

[0013] In this application, in order to further improve the performance of the catalyst, certain additives can be added. For example, a stabilizer, which effectively inhibits side reactions caused by too high activity of the titanium catalyst, thereby inhibiting the generation of colored functional group terminal vinyl groups. The stabilizer can be a phosphate stabilizer, and the phosphate stabilizer is selected from one or two of trioctyl phosphate, tributyl phosphate, triethyl phosphate, tripropyl phosphate, triisopropyl phosphate, triphenyl phosphate, trimethyl phosphate. However, the additives in this application are not limited to this, and those skilled in the art can add certain additives according to the use environment of the novel organotitanium-based polyester catalyst.

[0014] The second aspect of the present invention provides a preparation method of a novel organotitanium-based polyester catalyst, and the preparation method includes the following steps:

[0015] (1) Under the protection of an inert gas, mix a titanate with a heterocyclic benzyl alcohol at a certain temperature to obtain a preliminary mixture;

[0016] (2) Raise the temperature of step (1) to 70°C - 120°C, and continue the reaction under a pressure of 0.3 to 0.7 mbar to obtain a second mixture;

[0017] (3) Raise the temperature of step (2), and gradually reduce the vacuum to below 0.1 mbar and continue the reaction to obtain the catalyst main body.

[0018] Optionally, in step (1), the certain temperature is 20°C - 90°C. Optionally, in step (1), the certain temperature is 30°C - 60°C. Optionally, in step (1), the certain temperature is 40 - 50°C.

[0019] Optionally, in step (2), the reaction temperature is 80°C - 120°C. Optionally, in step (2), the reaction temperature is 80 - 100°C, and the reaction time is 0.5 - 2 h.

[0020] Optionally, in step (3), the reaction temperature is 110°C - 200°C. Optionally, in step (3), the reaction temperature is 110 - 170°C. Optionally, in step (3), the reaction temperature is 110 - 150°C, and the reaction time is 1 - 3 h.

[0021] Optionally, in step (1), the molar ratio of titanate to heterocyclic benzyl alcohol is 1:2.5 - 6.5. Optionally, in step (1), the molar ratio of titanate to heterocyclic benzyl alcohol is 1:2.5 - 4.5. Optionally, in step (1), the molar ratio of titanate to heterocyclic benzyl alcohol is 1:3.0 - 4.0.

[0022] In some embodiments of the present invention, the method for preparing the novel organic titanium-based polyester catalyst further comprises the following steps:

[0023] (4) Add a stabilizer to the catalyst main body obtained in step (3) and continue the reaction to obtain a novel organic titanium-based polyester catalyst. This novel organic titanium-based polyester catalyst is obtained by compounding the catalyst main body with the stabilizer, and can further stabilize the activity of the catalyst.

[0024] Optionally, in step (4), the molar ratio of the stabilizer to the titanate is 0.1 - 5:1. Optionally, in step (4), the molar ratio of the stabilizer to the titanate is 0.5 - 3:1.

[0025] Optionally, in step (4), the reaction temperature is 90 - 120°C, and the reaction time is 0.5 - 2 h. Optionally, in step (4), the reaction temperature is 95 - 110°C, and the reaction time is 0.5 - 2 h.

[0026] Optionally, the heterocycle in the heterocyclic benzyl alcohol is selected from one of pyridine, pyrrole, piperidine, furan, tetrahydrofuran, thiophene, and tetrahydrothiophene with different substituents. Among them, the substitution positions of the different substituents include ortho, meta, and para positions. The substituent is selected from one of -H, -Me, -OMe, -Et, -OEt, -CN, -CN, and -NO2 groups.

[0027] Preferably, the heterocyclic benzyl alcohol is one of furfuryl alcohol, 2-tetrahydrofuran methanol, 2-thiophene methanol, or 2-pyridine methanol.

[0028] Optionally, the titanate is one or more of tetrabutyl titanate, n-propyl titanate, isopropyl titanate, tetramethyl titanate, tert-butyl titanate, and diethyleneglycol titanate.

[0029] The third aspect of the present invention provides the application of the above novel organic titanium-based polyester catalyst in the preparation of polyester.

[0030] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0031] (1) While maintaining excellent activity, the novel organotitanium-based polyester catalyst of the present invention has good water resistance and thermal stability, and its catalytic activity is superior to that of the unchelated and modified titanate catalysts, solving the problems of poor color difference and difficult control of the end carboxyl value in the synthesis of aromatic-aliphatic polyester materials.

[0032] (2) The novel organotitanium-based polyester catalyst of the present invention is prepared by transesterification and chelation reaction of titanate with heterocyclic benzyl alcohol ligands under solvent-free conditions, introducing chelating groups to form stable chelates, so that the catalyst has excellent water resistance, thermal stability and high catalytic activity, thereby improving the quality of polyester products.

[0033] (3) The novel organotitanium-based polyester catalyst of the present invention is obtained by compounding the catalyst main body with a stabilizer. Adding the stabilizer can further stabilize the activity of the catalyst and further inhibit the generation of colored functional groups.

[0034] (4) The preparation of the titanium-based catalyst shown in the present invention is simple and can be applied to large-scale production. Description of the Drawings

[0035] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0036] Figure 1 Shows the NMR spectrum of the novel organotitanium-based polyester catalyst obtained in Example 1 of the present invention;

[0037] Figure 2 Shows the NMR spectrum of the novel organotitanium-based polyester catalyst obtained in Example 3 of the present invention;

[0038] Figure 3 Is the tensile property diagram of the polyester material prepared from the novel organotitanium-based polyester catalyst obtained in Example 1 of the present invention. Detailed Embodiments

[0039] In order to more clearly illustrate the overall concept of the present invention, the following will be described in detail by way of examples in conjunction with the drawings of the specification.

[0040] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0041] Example 1

[0042] The preparation method of the novel organotitanium-based polyester catalyst includes the following steps:

[0043] (1) Under an anhydrous and anaerobic environment, tetrabutyl titanate (0.1 mol) and furfuryl alcohol (0.25 mol) were mixed at 30 °C and stirred at a low speed to form a homogeneous system.

[0044] (2) Then, it was gradually heated to 70 °C and the reaction was maintained for 1 hour under a pressure of 0.5 mbar.

[0045] (3) The reaction temperature was further raised to 110 °C, and at the same time the vacuum degree was reduced to 0.1 mbar, and stirred for 2 hours to remove volatile by-products, obtaining the catalyst main body. Among them, R1 is a n-butyl group, R2 is a n-butyl group, X is O, and the heterocyclic ring is a furan ring.

[0046] (4) Finally, the reaction temperature was lowered to 90 °C, and trioctyl phosphate (0.05 mol) was added as a stabilizer and stirred for 1 hour to obtain a novel organic titanium-based polyester catalyst. Subsequently, it was cooled to room temperature, and the final product was encapsulated in an anhydrous sealed container and stored after filling with nitrogen.

[0047] Example 2

[0048] The preparation method of the novel organic titanium-based polyester catalyst includes the following steps:

[0049] (1) Under an anhydrous and anaerobic environment, tetrabutyl titanate (0.1 mol) and 2-tetrahydrofuran methanol (0.25 mol) were mixed at 60 °C and stirred at a low speed to form a homogeneous system.

[0050] (2) Then, it was gradually heated to 100 °C and the reaction was maintained for 1 hour under a pressure of 0.5 mbar.

[0051] (3) The reaction temperature was further raised to 150 °C, and at the same time the vacuum degree was reduced to 0.1 mbar, and stirred for 2 hours to remove volatile by-products, obtaining the catalyst main body. Among them, R1 is a n-butyl group, R2 is a n-butyl group, X is O, and the heterocyclic ring is a tetrahydrofuran ring.

[0052] (4) Finally, when the reaction temperature was lowered to 100 °C, trioctyl phosphate (0.05 mol) was added as a stabilizer and stirred for 1 hour to obtain a novel organic titanium-based polyester catalyst. Subsequently, it was cooled to room temperature, and the final product was encapsulated in an anhydrous sealed container and stored after filling with nitrogen.

[0053] Example 3

[0054] The preparation method of the novel organic titanium-based polyester catalyst includes the following steps:

[0055] (1) Under an anhydrous and anaerobic environment, tetrabutyl titanate (0.1 mol) and 2-thiophene methanol (0.25 mol) were mixed at 40 °C and stirred at a low speed to form a homogeneous system.

[0056] (2) Then, gradually heat to 80 °C and maintain the reaction for 1 hour under a pressure of 0.5 mbar.

[0057] (3) Continue to raise the reaction temperature to 110 °C, meanwhile reduce the vacuum degree to 0.1 mbar, and stir for 2 hours to remove volatile by-products, obtaining the catalyst main body. Wherein, R1 is n-butyl, R2 is n-butyl, X is S, and the heterocycle is a thiophene ring.

[0058] (4) Finally, when the reaction temperature is lowered to 100 °C, add trioctyl phosphate (0.05 mol) as a stabilizer, stir for 1 hour, obtaining the novel organotitanium-based polyester catalyst. Then cool to room temperature, and the final product is encapsulated in an anhydrous sealed container and stored after filling with nitrogen.

[0059] Example 4

[0060] The preparation method of the novel organotitanium-based polyester catalyst includes the following steps:

[0061] (1) Under an anhydrous and anaerobic environment, mix tetrabutyl titanate (0.1 mol) with 2-pyridinemethanol (0.25 mol) at 40 °C, and stir at a low speed to form a homogeneous system.

[0062] (2) Then, gradually heat to 80 °C and maintain the reaction for 1 hour under a pressure of 0.5 mbar.

[0063] (3) Continue to raise the reaction temperature to 110 °C, meanwhile reduce the vacuum degree to 0.1 mbar, and stir for 2 hours to remove volatile by-products, obtaining the catalyst main body. Wherein, R1 is n-butyl, R2 is n-butyl, X is N, and the heterocycle is a pyridine ring.

[0064] (4) Finally, when the reaction temperature is lowered to 100 °C, add trioctyl phosphate (0.05 mol) as a stabilizer, stir for 1 hour, obtaining the novel organotitanium-based polyester catalyst. Then cool to room temperature, and the final product is encapsulated in an anhydrous sealed container and stored after filling with nitrogen.

[0065] Example 5

[0066] The preparation method of the novel organotitanium-based polyester catalyst includes the following steps:

[0067] (1) Under an anhydrous and anaerobic environment, mix tetrabutyl titanate (0.1 mol) with furfuryl alcohol (0.4 mol) at 40 °C, and stir at a low speed to form a homogeneous system.

[0068] (2) Then, gradually heat to 80 °C and maintain the reaction for 1 hour under a pressure of 0.5 mbar.

[0069] (3) Raise the reaction temperature to 110 °C continuously, and at the same time reduce the vacuum degree to 0.1 mbar, and stir for 2 hours to remove volatile by-products, obtaining the catalyst main body.

[0070] (4) Finally, when the reaction temperature is reduced to 100 °C, add trioctyl phosphate (0.05 mol) as a stabilizer, stir for 1 hour, obtaining the novel organic titanium-based polyester catalyst. Then cool to room temperature, and the final product is encapsulated in an anhydrous sealed container and stored after filling with nitrogen.

[0071] Example 6

[0072] The preparation method of the novel organic titanium-based polyester catalyst comprises the following steps:

[0073] (1) Under an anhydrous and oxygen-free environment, mix isopropyl titanate (0.1 mol) with furfuryl alcohol (0.25 mol) at 40 °C, and stir at a low speed to form a homogeneous system.

[0074] (2) Then, gradually heat to 80 °C, and keep the reaction for 1 hour under a pressure of 0.5 mbar.

[0075] (3) Raise the reaction temperature to 110 °C continuously, and at the same time reduce the vacuum degree to 0.1 mbar, and stir for 2 hours to remove volatile by-products, obtaining the catalyst main body.

[0076] (4) Finally, when the reaction temperature is reduced to 100 °C, add trioctyl phosphate (0.05 mol) as a stabilizer, stir for 1 hour, obtaining the novel organic titanium-based polyester catalyst. Then cool to room temperature, and the final product is encapsulated in an anhydrous sealed container and stored after filling with nitrogen.

[0077] Example 7

[0078] The preparation method of the novel organic titanium-based polyester catalyst comprises the following steps:

[0079] (1) Under an anhydrous and oxygen-free environment, mix tetrabutyl titanate (0.1 mol) with furfuryl alcohol (0.25 mol) at 90 °C, and stir at a low speed to form a homogeneous system.

[0080] (2) Then, gradually heat to 100 °C, and keep the reaction for 1 hour under a pressure of 0.5 mbar.

[0081] (3) Raise the reaction temperature to 190 °C continuously, and at the same time reduce the vacuum degree to 0.1 mbar, and stir for 2 hours to remove volatile by-products.

[0082] (4) Finally, the reaction temperature was lowered to 120 °C, and trioctyl phosphate (0.05 mol) was added as a stabilizer, and the mixture was stirred for 1 hour to obtain a novel organotitanium-based polyester catalyst. Subsequently, it was cooled to room temperature, and the final product was encapsulated in an anhydrous sealed container and stored after being filled with nitrogen.

[0083] Example 8

[0084] Based on Example 1, the main difference is that no stabilizer was added.

[0085] Example 9

[0086] Based on Example 2, the main difference is that no stabilizer was added.

[0087] Comparative Example 1

[0088] The main difference between this Comparative Example 1 and Example 1 is that tetrabutyl titanate was directly used as the catalyst.

[0089] Comparative Example 2

[0090] The main difference between this Comparative Example 2 and Example 1 is that tetraisopropyl titanate was directly used as the catalyst.

[0091] Test Example: Application of the catalyst in polyester preparation

[0092] 498 g of terephthalic acid, 396 g of adipic acid, and 648 g of butanediol were respectively added to the catalysts of the above Examples and Comparative Examples (based on the amount of polyester produced, the weight of titanium atoms was 200 ppm), and the mixture was made into a slurry, added to a polymerization kettle, and subjected to an esterification reaction. The esterification temperature was gradually increased from 180 °C to 220 °C, the pressure was atmospheric pressure, and the water generated by the reaction was discharged through a rectification device. After the esterification was completed, the pressure was reduced to atmospheric pressure, and the pressure was reduced by vacuum to a system pressure lower than 100 Pa, and at the same time, the temperature was gradually increased to 260 °C. When the system reaction reached 150 min, the reaction was stopped. Then, the product PBAT resin was extruded from the bottom of the polymerization kettle, cooled, and pelletized for performance testing.

[0093] ① Influence of the catalyst on the product color

[0094] The polyester samples prepared by the catalysts of the Examples and Comparative Examples were tested for color value (yellowness index b value) to analyze the modification effect of the catalyst. The B value was measured using a BYK6801 color difference meter from BYKGardner Company, and the results are shown in Table 1:

[0095] Table 1

[0096]

[0097]

[0098] As can be seen from Table 2, for the polyester synthesized using the novel organotitanium-based polyester catalyst of the present invention, the L value > 80, the a value < 8, and the b value < 10; while for the PBAT polyester synthesized using tetrabutyl titanate or tetraisopropyl titanate catalyst, the L value < 80, the a value > 11, and the b value > 17. The catalyst developed in the present invention significantly inhibits the occurrence of side reactions, thereby effectively improving the yellowing phenomenon of the PBAT polyester material and enhancing the color quality of the polyester.

[0099] ② Catalytic activity and thermal stability of the catalyst in different polyesters

[0100] 1. The molecular weight and melt index of the polyester samples prepared using the catalysts of the examples and comparative examples were tested to evaluate the catalytic efficiency of the catalyst and the quality of the product. The molecular weight was determined using a Waters 1515-2414 gel permeation chromatography (GPC) instrument, with chloroform as the mobile phase, a flow rate of 1 ml / min, a column temperature of 30 °C, and polystyrene as the standard sample. The melt index was detected in accordance with GB / TT3682-2000 "Determination of Melt Mass-Flow Rate and Melt Volume-Flow Rate of Thermoplastics". The terminal carboxyl value was tested in accordance with FZT 50012-2006 "Determination of Terminal Carboxyl Content in Polyester - Titrimetric Method". The results are shown in Table 2:

[0101] Table 2

[0102]

[0103]

[0104] As can be seen from Table 3, the catalyst of the present invention exhibits good catalytic activity in the synthesis of PBAT polyester, with a relatively high molecular weight and a relatively low melt index of the sample, and an ideal terminal carboxyl value; the catalyst shows good molecular weight control. Comparing Examples 1-9 with Comparative Examples 1 and 2, it can be seen that in the case where the ligand cannot be successfully coordinated and complexed, the main body of the catalyst is still titanate ester. Due to its poor hydrolysis resistance and thermal stability, its activity is extremely likely to decrease due to hydrolysis during the reaction, resulting in a lower molecular weight and a higher melt index. The introduction of the ligand increases the steric hindrance effect, thereby enhancing the thermal stability and hydrolysis resistance of the catalyst.

[0105] ③ Mechanical property testing

[0106] The tensile strength and elongation at break of the polyester samples prepared using the catalysts of the examples and comparative examples were tested to evaluate the influence of the catalyst on the mechanical properties of the product. According to the GB / T1040-2006 standard, dumbbell-shaped test specimens were cut, and tested using a universal tensile testing machine at a loading speed of 50 mm / min. Five specimens were tested to obtain the tensile strength and elongation at break. The results are shown in Table 3:

[0107] Table 3

[0108] Sample Tensile strength (MPa) Elongation at break (%) Example 1 26.5 780 Example 2 25.2 750 Example 3 22.7 760 Example 4 28.9 805 Example 5 24.2 770 Example 6 21.5 640 Example 7 20.3 598 Example 8 25.1 778 Example 9 25.0 745 Comparative Example 1 15.4 470 Comparative Example 2 14.9 487

[0109] As can be seen from Table 3, the PBAT polyester sample prepared by the catalyst of the present invention has excellent tensile properties. By comparing Examples 1-9 with Comparative Examples 1-3, it can be seen that the catalyst provided by the present invention has good water resistance and stability, can catalyze the polymerization of monomers smoothly to a relatively high molecular weight, and its tensile properties are significantly improved. Without ligand coordination and chelation, the main body of the catalyst is still titanate. Such titanate catalysts are prone to hydrolysis and inactivation, resulting in a low molecular weight of the resulting polymer and a corresponding decrease in its mechanical properties. Therefore, the ligand in the catalyst provided by the present invention plays an excellent role in the overall stability and hydrolysis resistance of the catalyst.

[0110] Figure 1 shows the 1 1H NMR spectrum of the catalyst obtained in Example 1. As can be seen from the spectrum, the peak area ratio of the characteristic peaks of n-butyl and furan groups in the obtained catalyst is 1:1, proving that the catalyst is successfully synthesized through the reaction-chelating process.

[0111] Figure 2 shows the 1 1H NMR spectrum of the catalyst obtained in Example 3. As can be seen from the spectrum, the peak area ratio of the characteristic peaks of n-butyl and thiophene groups in the obtained catalyst is 1:1, proving that the catalyst is successfully synthesized through the reaction-chelating process.

[0112] Figure 3 shows the tensile property data of the polyester material prepared by the catalyst obtained in Example 1. Referring to Figure 3 as shown, the PBAT polyester sample prepared by the catalyst of the present invention has excellent tensile properties.

[0113] The above are only the embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A novel organic titanium polyester catalyst, characterized in that: The novel organic titanium polyester catalyst comprises a catalyst body, and the structural formula of the catalyst body is as follows: Wherein, R1 and R2 are both alkyl chains, and X is a heteroatom.

2. The novel organic titanium polyester catalyst according to claim 1, characterized in that: R1 and R2 are both selected from alkyl groups containing 1 to 6 carbon atoms, and R1 and R2 are the same or different.

3. The novel organic titanium polyester catalyst according to claim 1, characterized in that: X is one of N, O or S atoms.

4. The novel organic titanium polyester catalyst according to claim 1, characterized in that: The heterocyclic ring has 5 to 8 carbon atoms.

5. The novel organic titanium polyester catalyst according to any one of claims 1 to 4, characterized in that: The mass content of titanium element is 1 to 10%.

6. The novel organic titanium polyester catalyst according to claim 1, characterized in that: The invention also includes a stabilizer, which is a phosphate stabilizer; further, the phosphate stabilizer is selected from one or two of trioctyl phosphate, tributyl phosphate, triethyl phosphate, tripropyl phosphate, triisopropyl phosphate, triphenyl phosphate, and trimethyl phosphate.

7. A method for preparing a novel organic titanium polyester catalyst, characterized in that: The preparation method comprises the following steps: (1) under the protection of inert gas, titanate and heterocyclic benzyl alcohol are mixed at a certain temperature to obtain a primary mixture; (2) raising the temperature of step (1) to 70° C.-120° C. and continuing the reaction at a pressure of 0.3-0.7 mbar to obtain a second mixture; (3) The temperature of step (2) is increased, and the vacuum degree is gradually reduced to below 0.1 mbar to continue the reaction, thereby obtaining a catalyst body.

8. The method for preparing the novel organic titanium polyester catalyst according to claim 7, characterized in that: In step (1), the molar ratio of titanate to heterocyclic benzyl alcohol is 1:(2.5-6.5).

9. The method for preparing the novel organic titanium polyester catalyst according to claim 7, characterized in that: The heterocyclic benzyl alcohol is selected from the group consisting of pyridine, pyrrole, piperidine, furan, tetrahydrofuran, thiophene and tetrahydrothiophene having different substituents; And / or the titanate is one or more of tetrabutyl titanate, n-propyl titanate, isopropyl titanate, tetramethyl titanate, tert-butyl titanate, and diethylene titanate.

10. Use of the novel organic titanium polyester catalyst according to any one of claims 1 to 6 in the preparation of polyester.

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