Polybutylene terephthalate adipate and preparation method thereof

Abstract

The invention discloses polybutylene terephthalate adipate and a preparation method thereof.The preparation method of the polybutylene terephthalate adipate comprises the steps that first alkyl titanate and a first complex are subjected to a reaction, and a first catalyst is obtained; adding a first catalyst into a terephthalic acid esterification reaction system to carry out terephthalic acid esterification reaction; adding a second catalyst into the adipic acid esterification reaction system to carry out adipic acid esterification reaction; and mixing the adipic acid esterification product and the terephthalic acid esterification product, adding an additive, carrying out a co-esterification reaction, and carrying out a pre-polycondensation reaction and a final polycondensation reaction to obtain the polybutylene adipate terephthalate. According to the method disclosed by the invention, high-efficiency preparation of the polybutylene terephthalate adipate under a phosphorus-free condition is realized, the consumption of alcohol required by reaction is reduced, and the product has good mechanical properties and rheological properties.

Description

Technical Field

[0001] The present invention relates to the field of polyester, and in particular to polybutylene terephthalate adipate and a preparation method thereof. Background Art

[0002] Among biodegradable plastics, polybutylene terephthalate adipate (PBAT) has a high degree of industrialization and is the mainstream product among biodegradable plastics. It is widely used in the production of agricultural mulch, textiles, medical supplies, disposable sanitary products, etc. However, how to further reduce production costs while improving the quality of PBAT products is an important difficulty facing PBAT.

[0003] In the preparation process of PBAT, phosphates and phosphites are usually introduced as heat stabilizers and chelating agents to reduce the formation of by-products, but the use of phosphorus compounds often not only increases the production cost, but its potential residues may also affect the final performance of the product. Compared with ethylene glycol, the raw material of PET, the price of 1,4-butanediol used in PBAT is relatively high. In addition, in the PBAT fractionation production process, compared with adipic acid (AA) fractionation, due to the poor solubility of terephthalic acid (PTA), in order to ensure the smooth progress of PTA fractionation, it is often necessary to increase the amount of catalyst used and the alcohol acid ratio is relatively high, which also leads to a further increase in production costs. Titanium metal has gradually replaced antimony metal in the synthesis of PBAT due to its high activity and non-toxicity. However, the high activity of titanium-based catalysts and excessive catalyst dosage will lead to an increase in side reactions, resulting in poor quality of PBAT finished products. Therefore, the regulation of the performance of titanium-based catalysts is an important research direction to improve product quality and reduce production costs. Summary of the invention

[0004] The present invention is based on the inventor's discovery and understanding of the following facts and problems: In the preparation process of PBAT, the use of phosphorus-containing compounds often not only increases the production cost, but its potential residue may also affect the final performance of the product. In the PBAT fractionation and esterification production process, due to the poor solubility of terephthalic acid, the alcohol acid ratio is relatively high, which further increases the production cost. The high activity of titanium-based catalysts and excessive catalyst dosage will lead to an increase in side reactions, resulting in the deterioration of the quality of PBAT finished products.

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiments of the present invention provide a polybutylene terephthalate adipate and a preparation method thereof, which utilizes a complex-coordinated titanate catalyst to achieve efficient preparation of polybutylene terephthalate adipate under phosphorus-free conditions, reduce the amount of alcohol required for the reaction, reduce the occurrence of polymer degradation and discoloration side reactions, and polybutylene terephthalate adipate has good mechanical properties and rheological properties.

[0006] The embodiment of the present invention provides a method for preparing polybutylene terephthalate adipate, comprising the following steps:

[0007] (1) reacting a first alkyl titanate and a first complex to obtain a first catalyst; adding the first catalyst to a terephthalic acid fractionation reaction system to carry out a terephthalic acid fractionation reaction to obtain a terephthalic acid fractionation product; the first complex comprises at least one of acetylacetonate, 3-(benzenesulfonyl)propionic acid, oleamide, 2-morpholineethanol, and β-mercaptoethylamine;

[0008] (2) adding the second catalyst to the adipic acid fractionation reaction system to carry out an adipic acid fractionation reaction to obtain an adipic acid fractionation product;

[0009] (3) After the esterification is completed, the adipate esterified product and the terephthalate esterified product are mixed, an additive is added, and a co-esterification reaction is carried out, followed by a preliminary polycondensation reaction and a final polycondensation reaction to obtain polybutylene terephthalate adipate.

[0010] The advantages and technical effects brought by the preparation method of polybutylene terephthalate adipate of the embodiment of the present invention are as follows: using a titanate catalyst coordinated by a complex to realize the efficient preparation of polybutylene terephthalate adipate under phosphorus-free conditions. Specifically, the alkyl titanate is modified by the complex to obtain a new titanate catalyst system, and a fractionation reaction is carried out. After the esterification is completed, the AA esterification product is introduced into the PTA esterification product for co-esterification reaction, and additives are added at the same time, and then a high-performance PBAT product is synthesized through pre-polycondensation and final polycondensation processes. On the basis of the original structure of the titanate, a variety of metal titanium complexes with different activities are obtained through the regulation of organic complexes, and the catalytic activity and stability of the titanate are adjusted. While ensuring the catalytic activity of the titanium metal active center, the side reactions of polymer degradation and discoloration are reduced, and the use of phosphates is avoided. The titanium-based catalyst system of the present invention does not require additional phosphate stabilizers, and the amount of alcohol required for the reaction is small. The synthesized PBAT product has good mechanical properties and rheological properties, L value>80, terminal carboxyl group<20mol / t, tensile strength>25MPa, elongation at break>700%, etc.

[0011] In some embodiments, in step (1), the first alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate;

[0012] and / or, the molar ratio of the first alkyl titanate to the first complex is 0.5:1.5-5.0;

[0013] And / or, the reaction temperature is 50-150°C;

[0014] And / or, the reaction time is 3-6h;

[0015] and / or, the solvent of the reaction comprises 1,4-butanediol;

[0016] And / or, the reaction pressure is 30-70 kPa.

[0017] In some embodiments, in the preparation system of polybutylene terephthalate adipate, the total mass of titanate esters of all added catalysts, calculated as the mass of titanium element, is 100-180 ppm of the mass of the theoretical product of polybutylene terephthalate adipate.

[0018] In some embodiments, in step (1), the terephthalic acid esterification reaction system also includes adipic acid.

[0019] In some embodiments, in step (1), the terephthalic acid fractionation reaction system includes terephthalic acid, adipic acid, 1,4-butanediol and a first catalyst, and the molar ratio of the acid to 1,4-butanediol is 1:1.3-1.8;

[0020] And / or, in the terephthalic acid fractionation reaction system, the total mass of the titanate of all added catalysts, calculated as the mass of the titanium element, is 50-120 ppm of the total mass of terephthalic acid, adipic acid and 1,4-butanediol;

[0021] And / or, the terephthalic acid fractionation reaction system further includes a second alkyl titanate;

[0022] and / or, the molar ratio of adipic acid to terephthalic acid is 5-20:100;

[0023] and / or, the temperature of the terephthalate esterification reaction is 210-240° C.;

[0024] And / or, the terephthalate esterification reaction time is 90-180 min;

[0025] And / or, the terephthalate esterification reaction is carried out under stirring, and the stirring speed is 100-300 rpm.

[0026] In some embodiments, in step (2), the adipic acid fractionation reaction system comprises adipic acid, 1,4-butanediol and a second catalyst, and the molar ratio of adipic acid to 1,4-butanediol is 1:1-1.3;

[0027] And / or, in the adipic acid fractionation reaction system, the total mass of all added catalyst titanates, calculated as the mass of titanium element, is 30-150 ppm of the total mass of adipic acid and 1,4-butanediol;

[0028] and / or, the temperature of the adipic acid esterification reaction is 150-200° C.;

[0029] And / or, the adipic acid esterification reaction time is 60-120min;

[0030] And / or, the adipic acid esterification reaction is carried out under stirring, and the stirring speed is 100-300 rpm.

[0031] In some embodiments, in step (2), the second catalyst includes a third catalyst and / or a third alkyl titanate.

[0032] In some embodiments, the third alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate;

[0033] And / or, the preparation method of the third catalyst includes: reacting a fourth alkyl titanate and a second complex to obtain a third catalyst; the fourth alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate; and the second complex includes at least one of acetylacetonic acid, 3-(benzenesulfonyl)propionic acid, oleamide, 2-morpholineethanol, and β-mercaptoethylamine.

[0034] In some embodiments, in step (3), the additive includes at least one of malic acid, citric acid, tartaric acid, and mandelic acid;

[0035] And / or, the mass of the additive is 200-2000ppm of the mass of the theoretical product of polybutylene terephthalate adipate;

[0036] And / or, the temperature of the co-esterification reaction is 220-240°C;

[0037] And / or, the co-esterification reaction time is 15-60min;

[0038] And / or, the co-esterification reaction is carried out under stirring, and the stirring speed is 100-300 rpm;

[0039] In some embodiments, in step (3), the temperature of the pre-polycondensation reaction is 220-240°C;

[0040] And / or, the pre-polycondensation reaction time is 0.5-2h;

[0041] And / or, the pressure of the pre-polycondensation reaction is 1-20 kPa;

[0042] And / or, the temperature of the final polycondensation reaction is 220-240°C;

[0043] And / or, the final polycondensation reaction time is 1-4h;

[0044] And / or, the pressure of the final polycondensation reaction is 20-200Pa.

[0045] The embodiment of the present invention provides polybutylene terephthalate adipate, which is prepared by the preparation method described in the embodiment of the present invention. In the embodiment of the present invention, PBAT has good mechanical properties and rheological properties, L value>80, terminal carboxyl group<20mol / t, tensile strength>25MPa, elongation at break>700%, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is the rheological properties diagram of PBAT products. DETAILED DESCRIPTION

[0047] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0048] A method for preparing polybutylene terephthalate adipate according to an embodiment of the present invention comprises the following steps:

[0049] (1) reacting a first alkyl titanate and a first complex to obtain a first catalyst; adding the first catalyst to a terephthalic acid fractionation reaction system to carry out a terephthalic acid fractionation reaction to obtain a terephthalic acid fractionation product; the first complex comprises at least one of acetylacetonate, 3-(benzenesulfonyl)propionic acid, oleamide, 2-morpholineethanol, and β-mercaptoethylamine;

[0050] (2) adding the second catalyst to the adipic acid fractionation reaction system to carry out an adipic acid fractionation reaction to obtain an adipic acid fractionation product;

[0051] (3) After the esterification is completed, the adipate esterified product and the terephthalate esterified product are mixed, an additive is added, and a co-esterification reaction is carried out, followed by a preliminary polycondensation reaction and a final polycondensation reaction to obtain polybutylene terephthalate adipate.

[0052] The preparation method of polybutylene terephthalate adipate of the embodiment of the present invention utilizes a titanate catalyst coordinated by a complex to realize the efficient preparation of polybutylene terephthalate adipate under phosphorus-free conditions. Specifically, the alkyl titanate is modified by the complex to obtain a new titanate catalyst system, and a fractionation reaction is carried out. After the esterification is completed, the AA esterification product is introduced into the PTA esterification product for co-esterification reaction, and additives are added at the same time, and then a high-performance PBAT product is synthesized through pre-polycondensation and final polycondensation processes. On the basis of the original structure of the titanate, a variety of metal titanium complexes with different activities are obtained through the regulation of organic complexes, and the catalytic activity and stability of the titanate are adjusted. While ensuring the catalytic activity of the titanium metal active center, the side reactions of polymer degradation and discoloration are reduced, and the use of phosphates is avoided. The titanium-based catalyst system of the present invention does not require additional phosphate stabilizers, and the amount of alcohol required for the reaction is small. The synthesized PBAT product has good mechanical properties and rheological properties, L value>80, terminal carboxyl group<20mol / t, tensile strength>25MPa, elongation at break>700%, etc.

[0053] In some embodiments, in step (1), the first alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate.

[0054] In some embodiments, in step (1), the first complex comprises at least one of acetylacetonate, 3-(benzenesulfonyl)propionic acid, oleamide, 2-morpholinoethanol, and β-mercaptoethylamine;

[0055] Among them, acetylacetonate belongs to the weak complex of titanate; 2-morpholinoethanol and 3-(benzenesulfonyl)propionic acid belong to the medium-strength complex of titanate; oleic acid amide and β-mercaptoethylamine belong to the strong complex of titanate;

[0056] Optionally, the first complex includes two of acetylacetonic acid, 3-(benzenesulfonyl)propionic acid, oleic acid amide, 2-morpholineethanol, and β-mercaptoethylamine; in a specific embodiment, the first complex includes oleic acid amide and acetylacetonic acid, and the molar ratio of oleic acid amide to acetylacetonic acid is 1:2-5, specifically, for example, 1:2, 1:3, 1:4, 1:5.

[0057] In the embodiments of the present invention, on the basis of the original structure of titanate, a variety of metal titanium complexes with different activities are obtained through the regulation of organic complexes to adjust the catalytic activity and stability of titanate. At the same time, the use of multi-functional complexes will also participate in the polymerization to a certain extent, increasing the degree of branching of the molecule.

[0058] In the embodiments of the present invention, the selection of different complexes can flexibly regulate the catalyst activity of titanate. The use of the above-mentioned weak titanate complex can increase the catalytic activity of titanium, but there are relatively more side reactions; the use of strong titanate complexes can reduce the occurrence of side reactions and reduce the catalytic activity of titanium, but at the same time, strong coordination will also lead to the weakening of the attack ability of long-chain alcohols on the metal titanium center in the transesterification reaction during esterification and polycondensation reactions, hindering the reaction. The complexes in the present invention can be used alone or in combination. When used in combination, the catalyst adopts a combination of titanates with different activities. For example, oleamide and acetylacetonate are combined to ensure the catalytic activity of the titanium metal active center while reducing the side reactions of polymer degradation and discoloration, and avoiding the use of phosphates.

[0059] In some embodiments, in step (1), the molar ratio of the first alkyl titanate to the first complex is 0.5:1.5-5.0, specifically, for example, 0.5:1.5, 0.5:2.0, 0.5:2.5, 0.5:3.0, 0.5:5; the reaction temperature is 50-150°C, specifically, for example, 50°C, 70°C, 100°C, 120°C, 150°C; the reaction time is 3-6h, specifically, specifically, for example, 3h, 4h, 5h, 6h; the solvent of the reaction includes 1,4-butanediol, optionally, the molar ratio of the first alkyl titanate and 1,4-butanediol is 1:10-20, specifically, for example, 1:10, 1:12, 1:15, 1:18, 1:20; the pressure of the reaction is 30-70kPa, specifically, for example, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa.

[0060] In the embodiment of the present invention, the reaction solvent includes 1,4-butanediol, which is conducive to the full dissolution reaction of the titanate and the complex, and can also be directly used after the new catalyst is formed to avoid subsequent solvent removal.

[0061] In some embodiments, in the preparation system of polybutylene terephthalate adipate, the total mass of titanate of all catalysts added is 100-180ppm of the mass of the theoretical product of polybutylene terephthalate adipate, specifically, for example, 100ppm, 120ppm, 140ppm, 160ppm, 180ppm. Wherein, ppm means one part per million. In the embodiment of the present invention, the titanium-based catalyst system does not require additional phosphate stabilizer, and the amount of titanate added in the reaction system is 100-180ppm based on the mass of the theoretical product.

[0062] In some embodiments, in step (1), the terephthalic acid fractionation reaction system also includes adipic acid. In the embodiments of the present invention, without changing the structure of the original PTA esterification reactor, the AA reactant is introduced into the PTA fractionation reaction, and the AA autocatalytic reaction increases the rate of formation of esters in the initial stage of the reaction, improves the solubility of PTA, accelerates the occurrence of the PTA fractionation reaction, and further effectively reduces the amount of catalyst and 1,4-butanediol required for the reaction.

[0063] In some embodiments, in step (1), the terephthalic acid fractionation reaction system includes terephthalic acid, adipic acid, 1,4-butanediol and a first catalyst; the molar ratio of the acid (terephthalic acid and adipic acid) to 1,4-butanediol is 1:1.3-1.8, specifically, for example, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8.

[0064] In some embodiments, in the step (1), in the terephthalic acid fractionation reaction system, the total mass of titanate esters of all added catalysts, calculated as the mass of titanium element, is 50-120 ppm of the total mass of terephthalic acid, adipic acid and 1,4-butanediol, specifically, for example, 50 ppm, 70 ppm, 90 ppm, 100 ppm, 120 ppm.

[0065] In some embodiments, in the step (1), in the terephthalic acid deesterification reaction system, the total mass of the titanate ester of the first catalyst added, calculated as the mass of the titanium element, is 50-120 ppm of the total mass of terephthalic acid, adipic acid and 1,4-butanediol, specifically, for example, 50 ppm, 70 ppm, 90 ppm, 100 ppm, 120 ppm.

[0066] In some embodiments, in the step (1), the terephthalic acid de-esterification reaction system further includes a second alkyl titanate. There is no special restriction on the amount of the second alkyl titanate, and the addition or non-addition and the amount thereof can be selected according to the catalyst activity adjustment needs. Optionally, in the terephthalic acid de-esterification reaction system, the total mass of the titanate of the added second alkyl titanate, calculated as the mass of the titanium element, is 50-120 ppm of the total mass of terephthalic acid, adipic acid and 1,4-butanediol, specifically, for example, 50 ppm, 70 ppm, 90 ppm, 100 ppm, 120 ppm.

[0067] In the embodiment of the present invention, in the terephthalic acid fractionation reaction system, on the basis of the first catalyst, the second alkyl titanate can be added or not. For example, when the complex of the first catalyst is a strong complex, the second alkyl titanate can be added as needed.

[0068] In some embodiments, in step (1), the molar ratio of adipic acid to terephthalic acid is 5-20:100, that is, n(adipic acid):n(terephthalic acid)=5-20%, specifically, for example, 5%, 7%, 10%, 12%, 15%, 18%, 20%.

[0069] In the embodiment of the present invention, without changing the structure of the original PTA esterification reactor, 5-20% of AA reactants are introduced into the PTA fractionation esterification reaction, and the generation rate of the esterified product in the initial stage of the reaction is increased through the AA autocatalytic reaction, the solubility of PTA is improved, the occurrence of the PTA fractionation esterification reaction is accelerated, and the amount of catalyst and 1,4-butanediol required for the reaction is further effectively reduced. When too much adipic acid is added, the acidity is too strong, which will corrode the original equipment and is not conducive to the long-term operation of the equipment.

[0070] In some embodiments, in the step (1), the temperature of the terephthalate esterification reaction is 210-240°C, specifically, for example, 210°C, 220°C, 230°C, 240°C; the time of the terephthalate esterification reaction is 90-180min, specifically, for example, 90min, 120min, 150min, 180min; the terephthalate esterification reaction is carried out under stirring, and the stirring speed is 100-300rpm.

[0071] In some embodiments, the adipic acid fractionation reaction system includes adipic acid, 1,4-butanediol, and a second catalyst; the molar ratio of adipic acid to 1,4-butanediol is 1:1-1.3, specifically, for example, 1:1, 1:1.1, 1:1.2, 1:1.3.

[0072] In some embodiments, in step (2), in the adipic acid fractionation reaction system, the total mass of all added catalyst titanates, calculated as the mass of titanium element, is 30-150 ppm of the total mass of adipic acid and 1,4-butanediol, specifically, for example, 30 ppm, 50 ppm, 80 ppm, 100 ppm, 120 ppm, 150 ppm.

[0073] In some embodiments, in the step (2), the second catalyst includes a third catalyst and / or a third alkyl titanate. In the embodiment of the present invention, the second catalyst can be a third catalyst or a third alkyl titanate or a combination of the two. There is no special restriction on the third catalyst or the third alkyl titanate. Optionally, the total mass of the titanate of the added third catalyst in terms of titanium element mass is 30-150ppm of the total mass of adipic acid and 1,4-butanediol, specifically, for example, 30ppm, 50ppm, 80ppm, 100ppm, 120ppm, 150ppm; the total mass of the titanate of the added third alkyl titanate in terms of titanium element mass is 30-150ppm of the total mass of adipic acid and 1,4-butanediol, specifically, for example, 30ppm, 50ppm, 80ppm, 100ppm, 120ppm, 150ppm.

[0074] In some embodiments, the third alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate.

[0075] In some embodiments, the preparation method of the third catalyst includes: reacting a fourth alkyl titanate and a second complex to obtain a third catalyst;

[0076] Optionally, the fourth alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate;

[0077] Optionally, the second complex comprises at least one of acetylacetonate, 3-(benzenesulfonyl)propionic acid, oleamide, 2-morpholinoethanol, and β-mercaptoethylamine;

[0078] Optionally, the molar ratio of the fourth alkyl titanate to the second complex is 0.5:1.5-5.0, specifically, for example, 0.5:1.5, 0.5:2.0, 0.5:2.5, 0.5:3.0, 0.5:5; the reaction temperature is 50-150°C, specifically, for example, 50°C, 70°C, 100°C, 120°C, 150°C; the reaction time is 3-6h, specifically, for example, 3 h, 4h, 5h, 6h; the solvent of the reaction includes 1,4-butanediol, optionally, the molar ratio of the fourth alkyl titanate to 1,4-butanediol is 1:10-20, specifically, for example, 1:10, 1:12, 1:15, 1:18, 1:20; the pressure of the reaction is 30-70kPa, specifically, for example, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa;

[0079] Optionally, the second complex includes two of acetylacetonic acid, 3-(benzenesulfonyl)propionic acid, oleic acid amide, 2-morpholineethanol, and β-mercaptoethylamine; in a specific embodiment, the second complex includes oleic acid amide and acetylacetonic acid, and the molar ratio of oleic acid amide to acetylacetonic acid is 1:2-5, specifically, for example, 1:2, 1:3, 1:4, 1:5.

[0080] In some embodiments, in the step (2), the temperature of the adipate esterification reaction is 150-200°C, specifically, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C; the time of the adipate esterification reaction is 60-120min, specifically, for example, 60min, 80min, 100min, 120min; the adipate esterification reaction is carried out under stirring, and the stirring speed is 100-300rpm.

[0081] In some embodiments, in step (3), after the esterification is completed, the esterification reaction liquid is clarified.

[0082] In some embodiments, in step (3), the additive includes at least one of malic acid, citric acid, tartaric acid, and mandelic acid.

[0083] In the embodiment of the present invention, the additive used is a plant extract, which has a wide range of sources and is inexpensive. Through the branching effect of the additive, the interaction between the PBAT molecular chains can be enhanced, and it has good mechanical properties, tensile strength>25MPa, elongation at break>700%, and at the same time improves the rheological properties of the melt, which is beneficial to the development of downstream products.

[0084] In some embodiments, the mass of the additive is 200-2000ppm of the mass of the theoretical product of polybutylene terephthalate adipate, specifically, for example, 200ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm. In the embodiment of the present invention, the amount of the additive added is 200-2000ppm, which is beneficial to enhance the interaction between PBAT molecular chains and improve mechanical properties and rheological properties.

[0085] In some embodiments, the temperature of the co-esterification reaction is 220-240°C, specifically, for example, 220°C, 230°C, 240°C; the time of the co-esterification reaction is 15-60min, specifically, for example, 15min, 30min, 45min, 60min; the co-esterification reaction is carried out under stirring, and the stirring speed is 100-300rpm.

[0086] In some embodiments, in step (3), the temperature of the pre-polycondensation reaction is 220-240°C, specifically, for example, 220°C, 230°C, 240°C; the time of the pre-polycondensation reaction is 0.5-2h, specifically, for example, 0.5h, 1h, 1.5h, 2h; the pressure of the pre-polycondensation reaction is 1-20kPa. In the embodiment of the present invention, the low vacuum pre-polycondensation is conducive to the slow extraction of the remaining 1,4-butanediol and the stability of the overall reaction system.

[0087] In some embodiments, in step (3), the temperature of the final polycondensation reaction is 220-240°C, specifically, for example, 220°C, 230°C, 240°C; the time of the final polycondensation reaction is 1-4h, specifically, for example, 1h, 2h, 3h, 4h; the pressure of the final polycondensation reaction is 20-200 Pa. In the embodiment of the present invention, the high vacuum final polycondensation is conducive to accelerating the final polycondensation reaction rate, shortening the reaction time, reducing the occurrence of side reactions, and obtaining high-quality PBAT products.

[0088] A polybutylene terephthalate adipate according to an embodiment of the present invention is prepared by the preparation method according to an embodiment of the present invention. In the embodiment of the present invention, PBAT has good mechanical properties and rheological properties, L value>80, terminal carboxyl group<20mol / t, tensile strength>25MPa, elongation at break>700%, etc.

[0089] In some embodiments, the polybutylene terephthalate adipate has an L value > 80, a terminal carboxyl group < 20 mol / t, a tensile strength > 25 MPa, and an elongation at break > 700%.

[0090] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0091] Rheometer test conditions: 190°C, shear rate range 0.1-650s -1 , dynamic viscosity test shear rate logarithmic change. All other test methods refer to "GB / T32366-2015 Biodegradable Polybutylene Terephthalate-Adipate (PBAT)".

[0092] Example 1

[0093] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0094] (1) 10 g of tetraethyl titanate, 23 g of oleic acid amide and 50 g of 1,4-butanediol were added to a 150 mL three-necked flask, and 37.8 g of acetylacetonate was slowly added within 15 min at a temperature of 80 °C and a pressure of 50 kPa. The mixture was heated and stirred for 4 h. After the reaction was completed, the mixture was allowed to stand to obtain Catalyst 1.

[0095] (2) Into a PTA esterification reaction kettle, 1520 g of terephthalic acid, 200 g of adipic acid, 1350 g of 1,4-butanediol, and 15 g of catalyst 1 (including solvent 1,4-butanediol) were added in sequence, the stirring speed was 200 rpm, the temperature was raised to 230° C. for esterification reaction for 2 h, and the terephthalic acid esterification product was obtained.

[0096] (3) Into the AA esterification reaction kettle, 1250 g of adipic acid, 950 g of 1,4-butanediol, and 1.5 g of tetraethyl titanate were added in sequence, the stirring speed was 200 rpm, and the temperature was raised to 200° C. for esterification reaction for 1 hour to obtain an adipic acid esterified product.

[0097] (4) When the esterification reaction liquid becomes clear and transparent, pour the reaction liquid from the AA reactor into the PTA reactor, add 2 g of malic acid, and continue the co-esterification reaction at 230°C for 45 min. Then, keep the temperature constant and reduce the reaction pressure to 5 kPa to continue the reaction for 1.5 h. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa to carry out a condensation reaction for 2.5 h to finally obtain the target PBAT product.

[0098] After water cooling, pelletizing and analysis, the synthesized PBAT has a melt index of 6.5 g / 10 min, a carboxyl group of 12.1 mol / t, hue of L-85.2, a-2.2, b-5.6, a tensile strength of 31 MPa, and an elongation at break of 780%.

[0099] Example 2

[0100] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0101] (1) 10 g of tetraethyl titanate, 24 g of 3-(benzenesulfonyl)propionic acid and 40 g of 1,4-butanediol were added to a 150 mL three-necked flask, heated and stirred at 120° C. and 30 kPa for 4 h, and allowed to stand after the reaction to obtain catalyst 2.

[0102] (2) Into a PTA esterification reaction kettle, 1520 g of terephthalic acid, 200 g of adipic acid, 1350 g of 1,4-butanediol, and 8 g of catalyst 2 were added in sequence, the stirring speed was 200 rpm, the temperature was raised to 230° C. for esterification reaction for 2 h, and the terephthalic acid esterification product was obtained.

[0103] (3) Into the AA esterification reaction kettle, 1250 g of adipic acid, 950 g of 1,4-butanediol, and 1.5 g of tetraethyl titanate were added in sequence, the stirring speed was 200 rpm, and the temperature was raised to 200° C. for esterification reaction for 1 hour to obtain an adipic acid esterified product.

[0104] (4) When the esterification reaction liquid becomes clear and transparent, pour the reaction liquid from the AA reactor into the PTA reactor, add 2 g of malic acid, and continue the co-esterification reaction at 230°C for 45 min. Then, keep the temperature constant and reduce the reaction pressure to 5 kPa to continue the reaction for 1.5 h. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa to carry out a condensation reaction. The reaction lasts for 3 h to finally obtain the target PBAT product.

[0105] After water cooling, pelletizing and analysis, the synthesized PBAT has a melt index of 7.8 g / 10 min, a carboxyl group of 14.8 mol / t, a hue of L-87.4, a-0.5, b-4.8, a tensile strength of 32 MPa, and an elongation at break of 815%.

[0106] Example 3

[0107] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0108] (1) 10 g of isopropyl titanate, 15 g of 2-morpholineethanol and 40 g of 1,4-butanediol were added to a 150 mL three-necked flask, heated and stirred at 120° C. and 30 kPa for 4 h, and allowed to stand after the reaction to obtain catalyst 3.

[0109] (2) Into a PTA esterification reaction kettle, 1520 g of terephthalic acid, 200 g of adipic acid, 1350 g of 1,4-butanediol, 1.5 g of isopropyl titanate and 5 g of catalyst 3 were added in sequence. The stirring speed was 200 rpm. The temperature was raised to 230° C. for 1 h to carry out esterification reaction. The esterification reaction time was 2 h to obtain a terephthalic acid esterification product.

[0110] (3) 1250 g of adipic acid, 950 g of 1,4-butanediol, and 5 g of catalyst 3 were added to an AA esterification reaction kettle in sequence, the stirring speed was 200 rpm, the temperature was raised to 200° C. for esterification reaction for 1 hour, and the esterification reaction time was 1 hour to obtain an adipic acid esterified product.

[0111] (4) When the esterification reaction liquid becomes clear and transparent, pour the reaction liquid from the AA reactor into the PTA reactor, add 2 g of malic acid, and continue the co-esterification reaction at 230°C for 45 min. Then, keep the temperature constant and reduce the reaction pressure to 5 kPa to continue the reaction for 1.5 h. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa to carry out a condensation reaction. The reaction lasts for 3 h to finally obtain the target PBAT product.

[0112] After water cooling, pelletizing and analysis, the synthesized PBAT had a melt index of 7.4 g / 10 min, a carboxyl group of 14.3 mol / t, hue of L-86.3, a-0.8, b-4.9, a tensile strength of 29 MPa and an elongation at break of 805%.

[0113] Example 4

[0114] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0115] (1) 10 g of isopropyl titanate, 4 g of β-mercaptoethylamine and 40 g of 1,4-butanediol were added to a 150 mL three-necked flask, heated and stirred at 60° C. and 60 kPa for 4 h, and allowed to stand after the reaction to obtain catalyst 4.

[0116] (2) Into a PTA esterification reaction kettle, 1520 g of terephthalic acid, 200 g of adipic acid, 1350 g of 1,4-butanediol, 2.0 g of isopropyl titanate and 4 g of catalyst 4 were added in sequence. The stirring speed was 200 rpm. The temperature was raised to 230° C. for 1 h to carry out esterification reaction. The esterification reaction time was 2 h to obtain a terephthalic acid esterification product.

[0117] (3) 1250 g of adipic acid, 950 g of 1,4-butanediol, and 4 g of catalyst 4 were added to an AA esterification reaction kettle in sequence, the stirring speed was 200 rpm, the temperature was raised to 200° C. for esterification reaction for 1 hour, and the esterification reaction time was 1 hour to obtain an adipic acid esterified product.

[0118] (4) When the esterification reaction liquid becomes clear and transparent, pour the reaction liquid from the AA reactor into the PTA reactor, add 2 g of malic acid, and continue the co-esterification reaction at 230°C for 45 min. Then, keep the temperature constant and reduce the reaction pressure to 5 kPa and continue the reaction for 1.5 h. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa, carry out a condensation reaction, and react for 2.5 h to finally obtain the target PBAT product.

[0119] After water cooling, pelletizing and analysis, the synthesized PBAT has a melt index of 5.4 g / 10 min, a carboxyl group of 16.5 mol / t, hue of L-84.6, a-1.7, b-6.2, a tensile strength of 30 MPa, and an elongation at break of 764%.

[0120] Example 5

[0121] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0122] (1) 10 g of tetraethyl titanate, 23 g of oleic acid amide and 50 g of 1,4-butanediol were added to a 150 mL three-necked flask, and 37.8 g of acetylacetonate was slowly added within 15 min at a temperature of 80 °C and a pressure of 50 kPa. The mixture was heated and stirred for 4 h. After the reaction was completed, the mixture was allowed to stand to obtain Catalyst 1.

[0123] (2) Into a PTA esterification reaction kettle, 1520 g of terephthalic acid, 300 g of adipic acid, 1400 g of 1,4-butanediol, and 15 g of catalyst 1 were added in sequence, the stirring speed was 200 rpm, the temperature was raised to 230° C. for esterification reaction for 2 h, and the terephthalic acid esterification product was obtained.

[0124] (3) Into the AA esterification reaction kettle, 1150 g of adipic acid, 900 g of 1,4-butanediol, and 1.5 g of tetraethyl titanate were added in sequence, the stirring speed was 200 rpm, the temperature was raised to 200 °C within 1 hour for esterification reaction, and the esterification reaction time was 1 hour to obtain an adipic acid esterification product.

[0125] (4) When the esterification reaction liquid becomes clear and transparent, pour the reaction liquid from the AA reactor into the PTA reactor, add 2.0 g of citric acid, and continue the co-esterification reaction at 230°C for 45 minutes. Then, keep the temperature constant and reduce the reaction pressure to 5 kPa to continue the reaction for 1.5 hours. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa to carry out a condensation reaction. The reaction is continued for 2 hours to finally obtain the target PBAT product.

[0126] After water cooling, pelletizing and analysis, the synthesized PBAT has a melt index of 6.2 g / 10 min, a carboxyl group of 11.6 mol / t, hue of L-85.4, a-1.9, b-5.1, a tensile strength of 31 MPa, and an elongation at break of 752%.

[0127] Example 6

[0128] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0129] (1) 10 g of tetraethyl titanate, 23 g of oleic acid amide and 50 g of 1,4-butanediol were added to a 150 mL three-necked flask, and 37.8 g of acetylacetonate was slowly added within 15 min at a temperature of 80 °C and a pressure of 50 kPa. The mixture was heated and stirred for 4 h. After the reaction was completed, the mixture was allowed to stand to obtain Catalyst 1.

[0130] (2) Into a PTA esterification reaction kettle, 1520 g of terephthalic acid, 200 g of adipic acid, 1350 g of 1,4-butanediol, and 15 g of catalyst 1 were added in sequence, the stirring speed was 200 rpm, the temperature was raised to 230° C. for esterification reaction for 2 h, and the terephthalic acid esterification product was obtained.

[0131] (3) Into the AA esterification reaction kettle, 1250 g of adipic acid, 950 g of 1,4-butanediol, and 1.5 g of tetraethyl titanate were added in sequence, the stirring speed was 200 rpm, and the temperature was raised to 200° C. for esterification reaction for 1 hour to obtain an adipic acid esterified product.

[0132] (4) When the esterification reaction liquid becomes clear and transparent, pour the reaction liquid from the AA reactor into the PTA reactor, add 2 g of mandelic acid, and continue the co-esterification reaction at 230°C for 45 min. Then, keep the temperature constant and reduce the reaction pressure to 5 kPa to continue the reaction for 1.5 h. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa to carry out a condensation reaction. The reaction is continued for 2 h to finally obtain the target PBAT product.

[0133] After water cooling, pelletizing and analysis, the synthesized PBAT has a melt index of 4.9 g / 10 min, a carboxyl group of 13.7 mol / t, hue of L-84.0, a-2.0, b-6.2, a tensile strength of 33 MPa, and an elongation at break of 843%.

[0134] Comparative Example 1

[0135] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0136] (1) Into a PTA esterification reaction kettle, 1520 g of terephthalic acid, 1600 g of 1,4-butanediol, 2.5 g of tetraethyl titanate and 2.4 g of triphenyl phosphate were added in sequence, the stirring speed was 200 rpm, the temperature was raised to 230° C. for 1 h to carry out esterification reaction, and the esterification reaction time was 3 h to obtain a terephthalic acid esterification product.

[0137] (2) 1450 g of adipic acid, 1250 g of 1,4-butanediol, 1.5 g of tetraethyl titanate and 1.3 g of triphenyl phosphate were added to an AA esterification reaction kettle in sequence, the stirring speed was 200 rpm, the temperature was raised to 200° C. for esterification reaction for 1.5 h, and an adipic acid esterification product was obtained.

[0138] (3) When the esterification reaction liquid becomes clear and transparent, pour the reaction liquid from the AA reactor into the PTA reactor and continue the co-esterification reaction at 230°C for 45 minutes. Then, keep the reaction temperature unchanged and reduce the reaction pressure to 5 kPa to continue the reaction for 1.5 hours. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa to carry out a condensation reaction. The reaction is continued for 3 hours to finally obtain the target PBAT product.

[0139] After water cooling, pelletizing and analysis, the synthesized PBAT has a melt index of 8.5 g / 10 min, a carboxyl group of 34.0 mol / t, hue of L-81.2, a-3.6, b-7.5, a tensile strength of 23 MPa, and an elongation at break of 575%.

[0140] Comparative Example 2

[0141] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0142] (1) In a PTA esterification reaction kettle, 1520 g of terephthalic acid, 200 g of adipic acid, 1350 g of 1,4-butanediol, and 2.5 g of tetraethyl titanate were added in sequence, the stirring speed was 200 rpm, the temperature was raised to 230° C. for esterification reaction for 2 h, and the terephthalic acid esterification product was obtained.

[0143] (2) Into the AA esterification reaction kettle, 1250 g of adipic acid, 950 g of 1,4-butanediol, and 1.5 g of tetraethyl titanate were added in sequence, the stirring speed was 200 rpm, and the temperature was raised to 200° C. for esterification reaction for 1 hour to obtain an adipic acid esterification product.

[0144] (3) When the esterification reaction liquid becomes clear and transparent, pour the reaction liquid from the AA reactor into the PTA reactor, add 2 g of malic acid, and continue the co-esterification reaction at 230°C for 45 min. Then, keep the temperature constant and reduce the reaction pressure to 5 kPa and continue the reaction for 1.5 h. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa and react for 5 h to finally obtain the target PBAT product.

[0145] After water cooling, pelletizing and analysis, the synthesized PBAT had a melt index of 62.2 g / 10 min (the melt index was too high to test the mechanical properties), a carboxyl group of 15.0 mol / t, and a hue of L-74.4, a-7.6, and b-10.5.

[0146] Comparative Example 3

[0147] A method for preparing polybutylene terephthalate adipate comprises the following steps:

[0148] (1) In a PTA esterification reaction kettle, 1520 g of terephthalic acid, 1600 g of 1,4-butanediol, and 9.8 g of diisopropyl diacetylacetonate titanate were added in sequence, the stirring speed was 200 rpm, the temperature was raised to 230° C. for 1 h to carry out esterification reaction, and the esterification reaction time was 3 h to obtain a terephthalic acid esterification product.

[0149] (2) 1450 g of adipic acid, 1250 g of 1,4-butanediol, and 1.5 g of tetraethyl titanate were added to an AA esterification reaction kettle in sequence, the stirring speed was 200 rpm, the temperature was raised to 200° C. for esterification reaction for 1.5 h, and an adipic acid esterification product was obtained.

[0150] (3) When the esterification reaction liquid becomes clear, pour the reaction liquid from the AA reactor into the PTA reactor and continue the co-esterification reaction at 230°C for 45 minutes. Then, keep the reaction temperature unchanged and reduce the reaction pressure to 5 kPa to continue the reaction for 1.5 hours. Then, continue to reduce the pressure to a high vacuum of 20-200 Pa to carry out the polycondensation reaction. The reaction lasts for 5 hours, and the polymerization eventually fails.

[0151] After water cooling, pelletizing and analysis, the synthesized PBAT had a melt index of 152.3 g / 10 min (the melt index was too high to test the mechanical properties), a carboxyl group of 14.0 mol / t, and a hue of L-83.2, a-1.6, and b-5.2.

[0152] As shown in Examples 1-6, the polybutylene terephthalate adipate prepared by the preparation method of the present invention has an L value of >80, a terminal carboxyl group of <20 mol / t, a tensile strength of >25 MPa, an elongation at break of >700%, and a melt index of 4-10 g / 10 min. Figure 1 As shown, the rheological properties of Examples 1-6 are better than those of Comparative Example 1, which indicates that the preparation method of the present invention does not require the addition of a phosphate stabilizer, uses a small amount of 1,4-butanediol, and the synthesized PBAT product has good mechanical properties and rheological properties.

[0153] In Comparative Example 1, no complex is added, triphenyl phosphate stabilizer is added, and the amount of tetrabutyl titanate and 1,4-butanediol is higher than that in Example 1. Adipic acid is not added during the PTA fractionation reaction, and no additives are added. In Comparative Example 1, no complex is added, and triphenyl phosphate stabilizer is required for the esterification reaction. The esterification time of Comparative Example 1 is longer than that of Example 1. This is because in Example 1, AA reactant is introduced into the PTA fractionation reaction, and the AA autocatalytic reaction increases the generation rate of the esterified product in the initial stage of the reaction, improves the solubility of PTA, accelerates the occurrence of the PTA fractionation reaction, and further effectively reduces the amount of catalyst and 1,4-butanediol required for the reaction. The terminal carboxyl group of the PBAT synthesized in Comparative Example 1 is greater than 20 mol / t, the tensile strength is less than 25 MPa, the elongation at break is less than 700%, and the mechanical properties and rheological properties are poor. This is because the solubility of terephthalic acid in 1,4-butanediol is poor, resulting in a high alcohol-acid ratio required for the esterification reaction of terephthalic acid. At the same time, the lack of additives causes the PBAT molecules to be linearly distributed, resulting in insufficient physical and chemical crosslinking between the branches.

[0154] In Comparative Example 2, no complex is added, nor is triphenyl phosphate stabilizer added, and tetraethyl titanate is used to replace the original catalyst 1. The melt index of the PBAT synthesized in Comparative Example 2 is 62.2g / 10min, the melt index is too high, and the L value is <80, which is even lower than the PBAT in Comparative Example 1. This is because triphenyl phosphate, as a stabilizer, can reduce the generation of side reactions when titanate is catalyzed. When only tetraethyl titanate is used as a catalyst alone, too many side reactions cause the product melt index to be high and the polymerization fails. In Example 1, a metal titanium complex catalyst 1 is used to adjust the catalytic activity and stability of the titanate, while ensuring the catalytic activity of the titanium metal active center, reducing the side reactions of polymer degradation and discoloration, and avoiding the use of phosphate.

[0155] In Comparative Example 3, no complex was added, the amount of 1,4-butanediol was higher than that in Example 1, and diisopropyl diacetylacetonate titanate was used as a catalyst. No adipic acid was added during the PTA fractionation reaction, and no additives were added. The polymerization of Comparative Example 3 failed because acetylacetone in diisopropyl diacetylacetonate titanate was easy to leave, resulting in excessive activity of the titanium element, further increase in by-products, and high product melt index, resulting in polymerization failure.

[0156] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0157] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for preparing polybutylene terephthalate adipate, characterized in that: The following steps are involved: (1) reacting a first alkyl titanate and a first complex to obtain a first catalyst; adding the first catalyst to a terephthalic acid fractionation reaction system to carry out a terephthalic acid fractionation reaction to obtain a terephthalic acid fractionation product; the first complex comprises at least one of acetylacetonate, 3-(benzenesulfonyl)propionic acid, oleamide, 2-morpholineethanol, and β-mercaptoethylamine; (2) adding the second catalyst to the adipic acid fractionation reaction system to carry out an adipic acid fractionation reaction to obtain an adipic acid fractionation product; (3) After the esterification is completed, the adipate esterified product and the terephthalate esterified product are mixed, an additive is added, and a co-esterification reaction is carried out, followed by a preliminary polycondensation reaction and a final polycondensation reaction to obtain polybutylene terephthalate adipate.

2. The method for preparing polybutylene terephthalate adipate according to claim 1, characterized in that: In the step (1), the first alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate; and / or, the molar ratio of the first alkyl titanate to the first complex is 0.5:1.5-5.0; And / or, the reaction temperature is 50-150°C; And / or, the reaction time is 3-6h; and / or, the solvent of the reaction comprises 1,4-butanediol; And / or, the reaction pressure is 30-70 kPa.

3. The method for preparing polybutylene terephthalate adipate according to claim 1, characterized in that: In the preparation system of polybutylene terephthalate adipate, the total mass of titanate of all added catalysts calculated as the mass of titanium element is 100-180 ppm of the mass of the theoretical product of polybutylene terephthalate adipate.

4. The method for preparing polybutylene terephthalate adipate according to claim 1, characterized in that: In the step (1), the terephthalic acid esterification reaction system also includes adipic acid.

5. The method for preparing polybutylene terephthalate adipate according to claim 4, characterized in that: In the step (1), the terephthalic acid fractionation reaction system comprises terephthalic acid, adipic acid, 1,4-butanediol and a first catalyst, and the molar ratio of the acid to the 1,4-butanediol is 1:1.3-1.8; And / or, in the terephthalic acid fractionation reaction system, the total mass of the titanate of all added catalysts, calculated as the mass of the titanium element, is 50-120 ppm of the total mass of terephthalic acid, adipic acid and 1,4-butanediol; And / or, the terephthalic acid fractionation reaction system further includes a second alkyl titanate; and / or, the molar ratio of adipic acid to terephthalic acid is 5-20:100; and / or, the temperature of the terephthalate esterification reaction is 210-240° C.; And / or, the terephthalate esterification reaction time is 90-180 min; And / or, the terephthalate esterification reaction is carried out under stirring, and the stirring speed is 100-300 rpm.

6. The method for preparing polybutylene terephthalate adipate according to claim 1, characterized in that: In the step (2), the adipic acid fractionation reaction system comprises adipic acid, 1,4-butanediol and a second catalyst, and the molar ratio of adipic acid to 1,4-butanediol is 1:1-1.3; And / or, in the adipic acid fractionation reaction system, the total mass of all added catalyst titanates, calculated as the mass of titanium element, is 30-150 ppm of the total mass of adipic acid and 1,4-butanediol; and / or, the temperature of the adipic acid esterification reaction is 150-200° C.; And / or, the adipic acid esterification reaction time is 60-120min; And / or, the adipic acid esterification reaction is carried out under stirring, and the stirring speed is 100-300 rpm.

7. The method for preparing polybutylene terephthalate adipate according to claim 1, characterized in that: In the step (2), the second catalyst includes a third catalyst and / or a third alkyl titanate.

8. The method for preparing polybutylene terephthalate adipate according to claim 7, characterized in that: The third alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate; And / or, the preparation method of the third catalyst includes: reacting a fourth alkyl titanate and a second complex to obtain a third catalyst; the fourth alkyl titanate includes at least one of tetraethyl titanate, tetrabutyl titanate, and isopropyl titanate; and the second complex includes at least one of acetylacetonic acid, 3-(benzenesulfonyl)propionic acid, oleamide, 2-morpholineethanol, and β-mercaptoethylamine.

9. The method for preparing polybutylene terephthalate adipate according to claim 1, characterized in that: In step (3), the additive includes at least one of malic acid, citric acid, tartaric acid, and mandelic acid; And / or, the mass of the additive is 200-2000ppm of the mass of the theoretical product of polybutylene terephthalate adipate; And / or, the temperature of the co-esterification reaction is 220-240°C; And / or, the co-esterification reaction time is 15-60min; And / or, the co-esterification reaction is carried out under stirring, and the stirring speed is 100-300 rpm.

10. The method for preparing polybutylene terephthalate adipate according to claim 1, characterized in that: In the step (3), the temperature of the pre-polycondensation reaction is 220-240°C; And / or, the pre-polycondensation reaction time is 0.5-2h; And / or, the pressure of the pre-polycondensation reaction is 1-20 kPa; And / or, the temperature of the final polycondensation reaction is 220-240°C; And / or, the final polycondensation reaction time is 1-4h; And / or, the pressure of the final polycondensation reaction is 20-200Pa.

11. A polybutylene terephthalate adipate, characterized in that: The method is prepared according to any one of claims 1 to 10.

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