Method and device for continuously preparing PBST and product thereof

Abstract

The invention provides a method and a device for continuously preparing PBST and a product thereof. The continuous production process of the PBST is realized by adopting the reaction rectifying tower and the tower reactor which are connected in parallel, the high-molecular-weight PBST product can be obtained by adopting the technical scheme, the reaction conversion rate is high, the equipment is simple, and the method is suitable for being applied to large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of PBST, and in particular relates to a method, a device and a product of continuously preparing PBST. Background Art

[0002] Polybutylene succinate terephthalate, abbreviated as PBST in English, is a terpolymer of 1,4-butanediol (BDO), 1,4-succinic acid (SA) and terephthalic acid (PTA). It combines the degradability of aliphatic polyesters with the excellent mechanical and thermal properties of aromatic polyesters. It has excellent physical properties and processing properties comparable to ordinary plastics, and has good biodegradability. It is in line with the development trend of low-carbon and environmental protection, and has a competitive price advantage in the market. Its products can be widely used in agriculture, forestry, food packaging, electronic and electrical industries, medical and health industries, and textile industries, etc., and have broad market prospects.

[0003] In the existing process, the production process of PBST ester is divided into three steps (such as Figure 2 As shown). First, terephthalic acid (PTA for short), 1,4-succinic acid (SA for short), and 1,4-butanediol (BDO for short) are prepared in a certain molar ratio. The raw materials are first added to the slurry preparation tank after being measured from the BDO storage tank, and then PTA and SA are put into the slurry preparation tank. Then, the prepared slurry is added to the reactor for esterification. After esterification, all the esterification steam of the two esterification kettles enters the esterification separation tower for vapor-liquid separation; the esterified product is pumped into the second esterification kettle by a pump, and then pumped into the pre-condensation kettle by a pump for pre-condensation, and then sent to the final polycondensation kettle for further reaction. However, in the existing process, the regulating valve on the pipeline of the esterification steam entering the esterification separation tower does not play a regulating role, and the pipeline is easily blocked by oligomers or impurities entrained by the vapor phase. In addition, the second esterification kettle has similar functions to the pre-condensation kettle, and the high-viscosity fluid makes the pipeline easy to block, the gas phase pipeline has large stress, the reactor is expensive, and it is not easy to repair and maintain in the later stage. Summary of the invention

[0004] In order to solve the above problems in the prior art, the present invention provides an industrial-scale production device and method for PBST. The method adopts a reaction distillation tower device combined with a tower reactor to obtain a PBST product, and the device type is simple, the investment is small, the energy consumption is low, and it is suitable for large-scale industrial production.

[0005] One of the objectives of the present invention is to provide a method for continuously preparing PBST, which includes: under the condition that a part of 1,4 - butanediol (BDO) enters from the top of the reactive distillation column, separately reacting a mixed slurry of terephthalic acid (PTA) and another part of 1,4 - butanediol, and a mixed slurry of succinic acid (SA) and another part of 1,4 - butanediol in the reactive distillation column to obtain esterified product A and esterified product B respectively, and then subjecting esterified product A and esterified product B to a polymerization reaction to obtain PBST.

[0006] According to the present invention, the method for continuously preparing PBST includes the following steps:

[0007] (1) Continuously conveying a slurry A of terephthalic acid and 1,4 - butanediol (Ⅰ) by a metering pump to reactive distillation column A for an esterification reaction, while 1,4 - butanediol (Ⅱ) enters reactive distillation column A from the top of the reactive distillation column, and reacting to obtain esterified product A;

[0008] (2) Continuously conveying a slurry B of succinic acid and 1,4 - butanediol (Ⅲ) by a metering pump to reactive distillation column B for an esterification reaction, while 1,4 - butanediol (Ⅳ) enters reactive distillation column B from the top of the reactive distillation column, and reacting to obtain esterified product B;

[0009] (3) Sending esterified product A and esterified product B to a tower reactor for further polymerization reaction to obtain PBST.

[0010] According to an embodiment of the present invention, in step (1) of the method for continuously preparing PBST:

[0011] The molar ratio of terephthalic acid to 1,4 - butanediol (Ⅰ) is 1:(1.05 - 1.5), preferably 1:(1.1 - 1.2);

[0012] The molar ratio of 1,4 - butanediol (Ⅰ) to 1,4 - butanediol (Ⅱ) is 1:(0.1 - 2), preferably 1:(0.4 - 1.2);

[0013] In reactive distillation column A, the operating temperature of the reaction section is 170 - 260°C, preferably 190 - 240°C;

[0014] In reactive distillation column A, the operating pressure of the reaction section is - 0.08 - + 0.1 MPaG, preferably - 0.06 - + 0.05 MPaG;

[0015] In reactive distillation column A, the operating conditions at the top of the rectification section are: temperature 60 - 150°C, pressure - 0.1 - + 0.1 MPaG; preferably, temperature 70 - 120°C, pressure - 0.08 - + 0.05 MPaG;

[0016] In the reactive distillation column A, the operating conditions at the bottom of the rectifying section are as follows: temperature 150 - 230°C, pressure -0.08 - +0.1 MPaG; preferably, temperature 180 - 220°C, pressure -0.06 - +0.05 MPaG;

[0017] The reaction residence time in the reactive distillation column A is 2 - 10 h, preferably 3.5 - 6.5 h;

[0018] In the esterification reaction, a catalyst (I) is further added. The catalyst (I) is preferably selected from at least one of titanium-based catalysts and rare earth catalysts. For example, the catalyst (I) includes but is not limited to at least one of tetrabutyl titanate and tetraisopropyl titanate; the dosage of the catalyst (I) is preferably 0.1 - 5 wt% of the total amount of 1,4-butanediol (I) and 1,4-butanediol (II), more preferably 0.5 - 3.0 wt%.

[0019] According to the embodiment of the present invention, in step (2) of the method for continuously preparing PBST:

[0020] The molar ratio of the 1,4-succinic acid to 1,4-butanediol (III) is 1:(1.05 - 1.5), preferably 1:(1.1 - 1.2);

[0021] The molar ratio of the 1,4-butanediol (III) to 1,4-butanediol (IV) is 1:(0.1 - 2.2), preferably 1:(0.4 - 1.1);

[0022] In the reactive distillation column B, the operating temperature in the reaction section is 170 - 260°C, preferably 190 - 240°C;

[0023] In the reactive distillation column B, the operating pressure in the reaction section is -0.08 - +0.1 MPaG, preferably -0.06 - +0.05 MPaG;

[0024] In the reactive distillation column B, the operating conditions at the top of the rectifying section are as follows: temperature 60 - 150°C, pressure -0.1 - +0.1 MPaG; preferably, temperature 70 - 120°C, pressure -0.08 - +0.05 MPaG;

[0025] In the reactive distillation column B, the operating conditions at the bottom of the rectifying section are as follows: temperature 150 - 230°C, pressure -0.08 - +0.1 MPaG; preferably, temperature 180 - 220°C, pressure -0.06 - +0.05 MPaG;

[0026] The reaction residence time in the reactive distillation column B is 2 - 10 h, preferably 3 - 6 h;

[0027] In the esterification reaction, a catalyst (II) is further added. The catalyst (II) is preferably selected from at least one of titanium-based catalysts and rare earth catalysts. For example, the catalyst (II) includes but is not limited to at least one of tin laurate and dibutyltin oxide. The dosage of the catalyst (II) is preferably 0.1-4.5 wt% of the total amount of 1,4-butanediol (III) and 1,4-butanediol (IV), and more preferably 0.5-3.5 wt%.

[0028] According to an embodiment of the present invention, in step (3) of the method for continuously preparing PBST:

[0029] The molar ratio of the esterified product A to the esterified product B is 1:(0.8-1.3), preferably 1:(0.9-1.1);

[0030] The tower reactor includes multiple stages of reactions. Among them, the reaction conditions for the first stage in the upper stage are: the reaction temperature is 210-270 °C, the reaction pressure is 100 Pa-90 kPa, and the reaction residence time is 1-7 h; the reaction conditions for the second stage in the middle stage are: the reaction temperature is 220-300 °C, the reaction pressure is 100 Pa-90 kPa, and the reaction residence time is 2-10 h; the reaction conditions for the last stage are: the reaction temperature is 220-270 °C, the reaction pressure is 50 Pa-1000 Pa, and the reaction residence time is 3-15 h; preferably, the reaction conditions for the first stage in the upper stage are: the reaction temperature is 220-260 °C, the reaction pressure is 500 Pa-80 kPa, and the reaction residence time is 2-5 h; the reaction conditions for the second stage in the middle stage are: the reaction temperature is 230-270 °C, the reaction pressure is 500 Pa-80 kPa, and the reaction residence time is 3-8 h; the reaction conditions for the last stage are: the reaction temperature is 230-260 °C, the reaction pressure is 60 Pa-600 Pa, and the reaction residence time is 5-13 h;

[0031] In the polymerization reaction, a catalyst (III) is further added. The catalyst (III) is preferably selected from at least one of titanium-based catalysts and rare earth catalysts. For example, the catalyst (III) includes but is not limited to at least one of tetrabutyl titanate and tetraisopropyl titanate. The dosage of the catalyst (III) is 0.05-5 wt% of the total amount of the esterified product A and the esterified product B, and preferably 0.1-3.5 wt%.

[0032] According to the present invention, in the method for continuously preparing PBST, the esterification rate of the reactive distillation column A is 85-99%, the esterification rate of the reactive distillation column B is 85-99%, and the esterification rate of the tower reactor reaches 98% or more.

[0033] The second object of the present invention is to provide a device for continuously preparing PBST, which uses the above method to continuously prepare PBST.

[0034] According to the present invention, the device for continuously preparing PBST includes: a reactive distillation column A and a reactive distillation column B connected in parallel, and a tower reactor connected to the bottoms of the reactive distillation column A and the reactive distillation column B through pipelines.

[0035] In the device for continuously preparing PBST according to an embodiment of the present invention:

[0036] The bottom material outlet pipelines of the reactive distillation column A and the reactive distillation column B are connected and communicated and connected to the material inlet of the tower reactor;

[0037] The reactive distillation column A and the reactive distillation column B each include an upper rectification section and a lower reaction section; preferably,

[0038] The height ratio of the rectification section to the reaction section is 1:(0.1 - 0.6), preferably 1:(0.15 - 0.4);

[0039] In the rectification section, an exhaust gas outlet is provided at the top of the rectification section, a 1,4 - butanediol inlet is provided at the upper side line of the rectification section, and an outlet for discharging the material containing 1,4 - butanediol is provided at the lower side line of the rectification section. The discharged material containing 1,4 - butanediol can be recycled as a reaction raw material after impurity removal; more preferably, the 1,4 - butanediol inlet is provided at 0.1% - 20% from top to bottom of the rectification section, and the outlet for discharging the material containing 1,4 - butanediol is provided at 0.1% - 20% from bottom to top of the rectification section;

[0040] The rectification section includes an upper packing section and a lower tray section. Preferably, the height of the upper packing section is 20 - 90% of the total height of the rectification section, more preferably 40 - 70%; the number of trays in the lower tray section is 1 - 20, more preferably 4 - 8; the reflux molar percentage of the rectification section is 0.5 - 3, more preferably 1 - 2;

[0041] In the reaction section, a material inlet is provided at the side line of the reaction section, and a material outlet is provided at the bottom of the reaction section; more preferably, in the reaction section, the material inlet is provided at the head of the reaction section or at 0 - 1 / 2 from top to bottom of the side line of the reaction section;

[0042] A stirring device is provided in the reaction section;

[0043] A heating inner coil is provided in the bottom kettle of the reaction section:

[0044] A jacket or an external half - pipe temperature control device is provided outside the reaction section.

[0045] According to the present invention, raw materials such as terephthalic acid, succinic acid, and 1,4-butanediol can be separately transported to the reactive distillation column, or can be mixed into a slurry in a slurry preparation tank and then transported to the reactive distillation column. According to an embodiment of the present invention, the material inlet of the reactive distillation column A is connected to the slurry preparation tank A through a pipeline. The slurry preparation tank A is provided with a stirring device. The side line of the slurry preparation tank A is provided with a terephthalic acid inlet and a 1,4-butanediol (I) inlet; in the reactive distillation column A, the reaction section is provided with a stirring device. The side line of the reaction section is provided with a mixed slurry inlet containing terephthalic acid and 1,4-butanediol (I). The bottom of the reaction section is provided with an oligomer A outlet. The lower side line of the rectification section is provided with an external discharge outlet for the 1,4-butanediol material. The upper side line of the rectification section is provided with a 1,4-butanediol (II) inlet. The top of the rectification section is provided with an exhaust gas external discharge outlet. According to an embodiment of the present invention, the material inlet of the reactive distillation column B is connected to the slurry preparation tank B through a pipeline. The slurry preparation tank A is provided with a stirring device. The side line of the slurry preparation tank B is provided with a succinic acid inlet and a 1,4-butanediol (III) inlet; in the reactive distillation column B, the reaction section is provided with a stirring device. The side line of the reaction section is provided with a mixed slurry inlet containing succinic acid and 1,4-butanediol (III). The bottom of the reaction section is provided with an oligomer B outlet. The lower side line of the rectification section is provided with an external discharge outlet for the 1,4-butanediol material. The upper side line of the rectification section is provided with a 1,4-butanediol (IV) inlet. The top of the rectification section is provided with an exhaust gas external discharge outlet.

[0046] According to an embodiment of the present invention, in the device for continuously preparing PBST, the tower reactor is a segmented tower reactor. Preferably, the tower reactor includes at least three reactors from top to bottom. More preferably, the first reactor in the upper section and the second reactor in the middle section are connected to form a closed reaction unit. The material outlet at the bottom of the second reactor is connected to the material inlet of the next reactor through a pipeline. The bottom of the last reactor is provided with a PBST product external discharge pipeline.

[0047] According to an embodiment of the present invention, in the device for continuously preparing PBST:

[0048] The material inlet of the tower reactor is arranged at the top of the first reactor or at 0 to 1 / 2 from the top down on the side line of the first reactor, preferably at the top;

[0049] The side line of the second reactor is provided with a gas phase external discharge outlet. Preferably, the gas phase external discharge outlet is arranged at the top of the second reactor or at 0 to 1 / 2 from the top down on the side line of the second reactor, more preferably at 1 / 5 to 1 / 3.

[0050] The last reactor section includes an upper cylindrical barrel and a lower inverted cone, and the diameter of the upper cylinder is the same as the diameter of the upper end of the lower inverted cone; specifically, the cone angle of the lower inverted cone is 15 to 120°, more preferably 30 to 100°; the height of the upper cylindrical barrel is 1 to 12 times, more preferably 1.2 to 6 times, the diameter of the upper cylindrical barrel; a distributor is arranged in the upper cylindrical barrel, preferably a grid distributor, to increase the contact area of material reaction and facilitate the removal of small molecules; more preferably, the distributor is arranged at 0 to 1 / 2 from the bottom up of the upper cylindrical barrel; a gas-phase discharge outlet is arranged on the side line at the lower end of the upper cylindrical barrel, preferably, the gas-phase discharge outlet is arranged above the distributor; the gas-phase discharge outlet is arranged at 1 / 2 to 7 / 8, preferably 2 / 3 to 3 / 4, from the top down on the side line of the upper cylindrical barrel.

[0051] A polymer outlet is arranged at the bottom of the tower reactor. Preferably, a material pump is arranged on the polymer outlet pipeline, and the material pump can adopt a pump device commonly used in the prior art. For example, one or a combination of a gear pump, a screw pump, and a rotor pump can be selected.

[0052] The third object of the present invention is to provide a PBST, which is prepared by using the above-mentioned method for continuously preparing PBST or the above-mentioned device for continuously preparing PSBT. Preferably, the melt index of the prepared PBST is 0.1 to 50 g / 10 min, and the viscosity is 500,000 to 1,500,000 cP.

[0053] The present invention combines a reactive distillation column and a tower reactor, reducing the application of the second esterification kettle and the pre-polycondensation kettle in the original process. Among them, part of 1,4-butanediol (BDO) is input at the top of the reactive distillation column and contacts the esterified product vapor in the reactive distillation column to achieve the effect of separating the esterified product vapor. After the esterified product vapor is separated, the BDO is recovered from the bottom of the rectification section by a pump, and the remaining gas flows out from the top of the tower.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0055] 1. The present invention combines a reactive distillation column and a tower reactor, with a high reaction conversion rate, and can prepare high-molecular-weight PBST products;

[0056] 2. The equipment type of the present invention is simple and is suitable for large-scale industrial production of PBST products. Description of the Drawings

[0057] Figure 1 It is a schematic diagram of the production device for continuously preparing PBST adopted by the present invention.

[0058] 1 - Reactive distillation column A, 2 - Reactive distillation column B, 3 - Tower reactor, 4 - Slurry preparation tank A, 5 - Slurry preparation tank B, 6 - Terephthalic acid transfer pipeline, 7 - 1,4 - Butanediol transfer pipeline, 8 - 1,4 - Butanediol (Ⅰ) transfer pipeline, 9 - 1,4 - Butanediol (Ⅱ) transfer pipeline, 10 - Mixed slurry A transfer pipeline containing terephthalic acid and 1,4 - butanediol (Ⅰ), 11 - Waste gas discharge pipeline of reactive distillation column A, 12 - 1,4 - Butanediol discharge pipeline of reactive distillation column A, 13 - Esterified product A transfer pipeline, 14 - Liquid pump A, 15 - 1,4 - Butanedioic acid transfer pipeline, 16 - 1,4 - Butanediol transfer pipeline, 17 - 1,4 - Butanediol (Ⅲ) transfer pipeline, 18 - 1,4 - Butanediol (Ⅳ) transfer pipeline, 19 - Mixed slurry B transfer pipeline containing 1,4 - butanedioic acid and 1,4 - butanediol (Ⅲ), 20 - Waste gas discharge pipeline of reactive distillation column B, 21 - 1,4 - Butanediol discharge pipeline of reactive distillation column A, 22 - Esterified product B transfer pipeline, 23 - Liquid pump B, 25 - First reactor, 26 - Second reactor, 27 - Third reactor, 28 - Second reactor product transfer pipeline, 24 - Material inlet of tower reactor, 29 - Gas phase discharge outlet C of tower reactor, 30 - Gas phase discharge outlet D of tower reactor, 31 - PBST product discharge pipeline, 32 - Gear pump, 33 - Grid distributor, 34 - PBST transfer pipeline.

[0059] Figure 2 Schematic diagram of the production device for continuously preparing PBST used in Comparative Example 1. Specific embodiments

[0060] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the protection scope of the present invention. Some non - essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0061] Example 1

[0062] The following is combined with Figure 1 to illustrate the production device and production method for continuously preparing PBST provided by the present invention.

[0063] Production device for continuously preparing PBST:

[0064] As Figure 1As shown in the figure, the production device for continuously preparing PBST includes a reactive distillation column A (1) and a reactive distillation column B (2) connected in parallel, and a tower reactor (3) connected to the bottoms of the reactive distillation column A and the reactive distillation column B through pipelines. The bottom material outlet pipelines of the reactive distillation column A (1) and the reactive distillation column B (2) are connected and connected to the material inlet of the tower reactor (3). The reactive distillation column A (1) and the reactive distillation column B (2) include an upper rectification section and a lower reaction section. A stirring device is arranged in the reaction section, and a jacket temperature control device is arranged on the periphery of the reaction section; the rectification section includes an upper packing section and a lower tray section. The height of the upper packing section is 60% of the total height of the rectification section. The number of trays in the lower tray section is 6, and the reflux molar percentage of the rectification section is 1.6.

[0065] The material inlet of the reactive distillation column A (1) is connected to a slurry preparation tank A (4) through a pipeline. The slurry preparation tank A (4) is provided with a stirring device. A terephthalic acid delivery pipeline inlet (6) and a 1,4-butanediol (Ⅰ) delivery pipeline inlet (8) are arranged on the side line of the slurry preparation tank A (4); in the reactive distillation column A (1), a stirring device is arranged in the reaction section. A mixed slurry delivery pipeline inlet (10) containing terephthalic acid and 1,4-butanediol (Ⅰ) is arranged on the side line of the reaction section. An oligomer A outlet (13) is arranged at the bottom of the reaction section. An external discharge outlet (14) for the material containing 1,4-butanediol is arranged on the lower side line of the rectification section. A 1,4-butanediol (Ⅱ) inlet (9) is arranged on the upper side line of the rectification section. An exhaust gas external discharge outlet (11) is arranged at the top of the rectification section. Among them, the height ratio of the rectification section to the reaction section is 1:0.25. The mixed slurry delivery pipeline inlet (10) is arranged at the head of the reaction section; taking the height of the rectification section as 10m as an example, the external discharge outlet (14) for the material containing 1,4-butanediol is arranged at 600mm from the top to the bottom of the rectification section, and the 1,4-butanediol (Ⅱ) inlet (9) is arranged at 950mm from the top to the bottom of the rectification section.

[0066] The material inlet of the reactive distillation column B (2) is connected to the slurry preparation tank B (5) through a pipeline. The slurry preparation tank A (5) is provided with a stirring device. The side line of the slurry preparation tank B (5) is provided with an inlet (15) for the 1,4 - butanedioic acid conveying pipeline and an inlet (17) for the 1,4 - butanediol (Ⅲ) conveying pipeline; in the reactive distillation column B (2), the reaction section is provided with a stirring device, and the side line of the reaction section is provided with an inlet (19) for the mixed slurry conveying pipeline containing 1,4 - butanedioic acid and 1,4 - butanediol (Ⅲ). The bottom of the reaction section is provided with an outlet (22) for oligomer B. The lower side line of the rectification section is provided with an outlet (21) for discharging the 1,4 - butanediol - containing material. The upper side line of the rectification section is provided with an inlet (18) for 1,4 - butanediol (Ⅳ). The top of the rectification section is provided with an exhaust gas discharge outlet (20). Among them, the height ratio of the rectification section to the reaction section is 1:0.2. The mixed slurry conveying pipeline inlet (10) is arranged at the head of the reaction section; taking the height of the rectification section as 10m as an example, the outlet (14) for discharging the 1,4 - butanediol - containing material is arranged at 600mm from the top down of the rectification section, and the inlet (9) for 1,4 - butanediol (Ⅱ) is arranged at 950mm from the top down of the rectification section.

[0067] The tower reactor (3) is a segmented tower reactor. The tower reactor includes three reactor segments, namely the first reactor (25), the second reactor (26), and the third reactor (27). The first reactor (25) and the second reactor (26) are connected to form a closed reaction unit. The bottom material outlet of the second reactor (26) is connected to the material inlet of the third reactor (27) through a pipeline (28). The bottom of the third reactor (27) is provided with a PBST product discharge pipeline (31). The material inlet (24) of the tower reactor is arranged at the upper end of the side line of the first reactor (25); the side line of the second reactor (26) is provided with a gas discharge outlet C (29), which is arranged at 1 / 4 from the top down of the second reactor; the third reactor (27) includes an upper cylindrical barrel and a lower inverted cone with a cone angle of 80°. The diameter of the upper cylindrical barrel is the same as the diameter of the upper end of the lower inverted cone; the height of the upper cylindrical barrel is 4 times the diameter. The lower side line of the upper cylindrical barrel is provided with a gas discharge outlet D (30), which is arranged at 2 / 3 from the top down of the upper cylindrical barrel; a grid distributor (33) is arranged in the upper cylindrical barrel, which is arranged at 1 / 3 from the bottom up of the upper cylindrical barrel.

[0068] The bottom of the tower reactor is provided with a polymer outlet, and a gear pump (32) is arranged on the polymer outlet pipeline (31).

[0069] A continuous production method for preparing PBST:

[0070] Adopt Figure 1 the device to continuously prepare PBST. The specific production method includes:

[0071] (1) Tetrabutyl titanate as catalyst (Ⅰ) and 1,4-butanediol (Ⅰ) are mixed and then pumped into the slurry preparation tank A together with terephthalic acid to obtain the mixed slurry A. The slurry A is continuously transported to the reactive distillation column A through a metering pump for esterification reaction. Meanwhile, 1,4-butanediol (Ⅱ) enters the reactive distillation column A from the top of the column as the reflux liquid. Among them, the molar ratio of terephthalic acid to 1,4-butanediol (Ⅰ) is 1:1.2, the molar ratio of 1,4-butanediol (Ⅰ) to 1,4-butanediol (Ⅱ) is 1:0.9, and the catalyst (Ⅰ) is 1.5% of the total amount of 1,4-butanediol (Ⅰ) and 1,4-butanediol (Ⅱ). In the reactive distillation column A, the operating conditions of the reaction section are 230 °C and -0.06 MPaG, and the operating conditions of the rectification section are 92 °C at the top, 218 °C at the bottom, -0.065 MPaG at the top, and -0.06 MPaG at the bottom. The reaction residence time in the reactive distillation column A is 5.5 h;

[0072] (2) Tin laurate as catalyst (Ⅱ) and 1,4-butanediol (Ⅲ) are mixed and then pumped into the slurry preparation tank B together with succinic acid to obtain the mixed slurry B. The slurry B is continuously transported to the reactive distillation column B through a metering pump for esterification reaction. Meanwhile, 1,4-butanediol (Ⅳ) enters the reactive distillation column B from the top of the column as the reflux liquid. Among them, the molar ratio of succinic acid to 1,4-butanediol (Ⅲ) is 1:1.15, the molar ratio of 1,4-butanediol (Ⅲ) to 1,4-butanediol (Ⅳ) is 1:1.1, and the catalyst (Ⅱ) is 1.2% of the total amount of 1,4-butanediol (Ⅲ) and 1,4-butanediol (Ⅳ). In the reactive distillation column B, the operating conditions of the reaction section are 210 °C and -0.06 MPaG, and the operating conditions of the rectification section are 90 °C at the top, 215 °C at the bottom, -0.065 MPaG at the top, and -0.06 MPaG at the bottom. The reaction residence time in the reactive distillation column B is 4 h;

[0073] (3) The esterified product A obtained from the reactive distillation column A and the esterified product B obtained from the reactive distillation column B are sent to a tower reactor for further polymerization, and tetrabutyl titanate as catalyst (Ⅲ) is added to obtain PBST. Among them, the molar ratio of the esterified product A to the esterified product B is 1:1.1, the dosage of the catalyst (Ⅲ) is 0.9% of the total amount of the esterified product A and the esterified product B. The operating conditions of the first reactor are: 245 °C, 20 kPa, and the reaction residence time is 3.5 h; the operating conditions of the second reactor are: 250 °C, 20 kPa, and the reaction residence time is 6 h; the operating conditions of the third reactor are: 255 °C, 80 Pa, and the reaction residence time is 11 h.

[0074] Using the above preparation method, the viscosity of the obtained PBST is 3,000 - 1,000,000 cP, and the melt index is 0.8 - 10 g / 10 min.

[0075] Example 2

[0076] The production device for continuously preparing PBST is the same as that in Example 1. The specific production method includes:

[0077] (1) Tetrabutyl titanate as catalyst (Ⅰ) and 1,4-butanediol (Ⅰ) are mixed and then pumped into the slurry preparation tank A simultaneously with terephthalic acid to obtain the mixed slurry A. The slurry A is continuously transported to the reactive distillation column A by a metering pump for esterification reaction. Meanwhile, 1,4-butanediol (Ⅱ) enters the reactive distillation column A from the top of the reactive distillation column as the reflux liquid. Among them, the molar ratio of terephthalic acid to 1,4-butanediol (Ⅰ) is 1:1.2, the molar ratio of 1,4-butanediol (Ⅰ) to 1,4-butanediol (Ⅱ) is 1:0.9, and catalyst (Ⅰ) is 1.5% of the total amount of 1,4-butanediol (Ⅰ) and 1,4-butanediol (Ⅱ). In the reactive distillation column A, the operating conditions of the reaction section are 230°C and -0.06 MPaG, and the operating conditions of the rectification section are 80°C at the top, 200°C at the bottom, -0.065 MPaG at the top, and -0.06 MPaG at the bottom. The reaction residence time in the reactive distillation column A is 5.5 h;

[0078] (2) Tin laurate as catalyst (Ⅱ) and 1,4-butanediol (Ⅲ) are mixed and then pumped into the slurry preparation tank B simultaneously with succinic acid to obtain the mixed slurry B. The slurry B is continuously transported to the reactive distillation column B by a metering pump for esterification reaction. Meanwhile, 1,4-butanediol (Ⅳ) enters the reactive distillation column B from the top of the reactive distillation column as the reflux liquid. Among them, the molar ratio of succinic acid to 1,4-butanediol (Ⅲ) is 1:1.15, the molar ratio of 1,4-butanediol (Ⅲ) to 1,4-butanediol (Ⅳ) is 1:1.1, and catalyst (Ⅱ) is 1.2% of the total amount of 1,4-butanediol (Ⅲ) and 1,4-butanediol (Ⅳ). In the reactive distillation column B, the operating conditions of the reaction section are 210°C and -0.06 MPaG, and the operating conditions of the rectification section are 85°C at the top, 205°C at the bottom, -0.065 MPaG at the top, and -0.06 MPaG at the bottom. The reaction residence time in the reactive distillation column B is 4 h;

[0079] (3) The esterified product A obtained from the reactive distillation column A and the esterified product B obtained from the reactive distillation column B are sent to a tower reactor together for further polymerization, and tetrabutyl titanate as the catalyst (Ⅲ) is added. PBST is obtained through the reaction. The molar ratio of the esterified product A to the esterified product B is 1:1.05, and the dosage of the catalyst (Ⅲ) is 0.9% of the total amount of the esterified product A and the esterified product B. The operating conditions of the first reactor are: 240 °C, 25 kPa, and the reaction residence time is 4 h; the operating conditions of the second reactor are: 255 °C, 25 kPaA, and the reaction residence time is 5.5 h; the operating conditions of the third reactor are: 250 °C, 60 Pa, and the reaction residence time is 12 h.

[0080] Using the above preparation method, the viscosity of the obtained PBST is 3,500 - 1,200,000 cP, and the melt index is 0.6 - 8 g / 10 min.

[0081] Example 3

[0082] Using Figure 1 the device (the same as in Example 1) to continuously prepare PBST. The specific production method includes:

[0083] (1) Tetrabutyl titanate as the catalyst (Ⅰ) and 1,4-butanediol (Ⅰ) are mixed and then pumped into the slurry preparation tank A together with terephthalic acid to obtain the mixed slurry A. The slurry A is continuously transported to the reactive distillation column A through a metering pump for esterification reaction. At the same time, 1,4-butanediol (Ⅱ) enters the reactive distillation column A from the top of the column as the reflux liquid. The molar ratio of terephthalic acid to 1,4-butanediol (Ⅰ) is 1:1.15, the molar ratio of 1,4-butanediol (Ⅰ) to 1,4-butanediol (Ⅱ) is 1:1.1, and the catalyst (Ⅰ) is 1.2% of the total amount of 1,4-butanediol (Ⅰ) and 1,4-butanediol (Ⅱ). In the reactive distillation column A, the operating conditions of the reaction section are 230 °C, -0.06 MPaG, and the operating conditions of the rectification section are 92 °C at the top, 218 °C at the bottom, -0.065 MPaG at the top, and -0.06 MPaG at the bottom. The reaction residence time of the reactive distillation column A is 5.5 h;

[0084] (2) The catalyst (II), tin laurate, and 1,4-butanediol (III) are mixed and then pumped into the slurry preparation tank B simultaneously with succinic acid to obtain the mixed slurry B. The slurry B is continuously transported to the reactive distillation column B through a metering pump for esterification reaction. Meanwhile, 1,4-butanediol (IV) enters the reactive distillation column B from the top of the reactive distillation column as the reflux liquid. Among them, the molar ratio of succinic acid to 1,4-butanediol (III) is 1:1.15, the molar ratio of 1,4-butanediol (III) to 1,4-butanediol (IV) is 1:1, and the catalyst (II) is 1.5% of the total amount of 1,4-butanediol (III) and 1,4-butanediol (IV). In the reactive distillation column B, the operating conditions of the reaction section are 210 °C and -0.06 MPaG, and the operating conditions of the rectification section are 90 °C at the top, 215 °C at the bottom, -0.065 MPaG at the top, and -0.06 MPaG at the bottom. The reaction residence time in the reactive distillation column B is 4 h;

[0085] (3) The esterified product A obtained from the reactive distillation column A and the esterified product B obtained from the reactive distillation column B are sent to a tower reactor together for further polymerization, and tetrabutyl titanate, the catalyst (III), is added. The PBST is obtained through the reaction. Among them, the molar ratio of the esterified product A to the esterified product B is 1:1.05, the dosage of the catalyst (III) is 0.9% of the total amount of the esterified product A and the esterified product B. The operating conditions of the first reactor are: 250 °C, 30 kPa, and the reaction residence time is 4 h; the operating conditions of the second reactor are: 255 °C, 30 kPaA, and the reaction residence time is 6 h; the operating conditions of the third reactor are: 260 °C, 200 Pa, and the reaction residence time is 12 h.

[0086] Using the above preparation method, the prepared PBST has a molecular weight of 2,500 - 450,000 cP and a melt index of 3 - 20 g / 10 min.

[0087] Comparative Example 1

[0088] Using Figure 2 the device (a device of the prior art) to continuously prepare PBST. The specific production method includes:

[0089] (1) The catalyst (I), tetrabutyl titanate, and 1,4-butanediol (I) are mixed and then pumped into the slurry preparation tank A simultaneously with terephthalic acid to obtain the mixed slurry A. The slurry A is continuously transported to the reaction kettle A through a metering pump for esterification reaction. Among them, the molar ratio of terephthalic acid to 1,4-butanediol (I) is 1:1.4, and the catalyst (I) is 0.8% of the total amount of 1,4-butanediol (I). In the reaction kettle A, the operating conditions are 235 °C and -0.04 MPaG, and the reaction residence time is 5 h;

[0090] (2) The catalyst (Ⅱ), tin laurate, and 1,4-butanediol (Ⅲ) are mixed and then pumped into the slurry preparation tank B together with succinic acid to obtain the mixed slurry B. The slurry B is continuously transported to the reaction kettle B by a metering pump for esterification reaction. Among them, the molar ratio of succinic acid to 1,4-butanediol (Ⅲ) is 1:1.45, and the catalyst (Ⅱ) is 0.8% of the total amount of 1,4-butanediol (Ⅲ). In the reaction kettle B, the operating conditions are 190 °C and -0.04 MPaG, and the reaction residence time is 3.6 h.

[0091] (3) After esterification, the esterification vapors from the two esterification kettles all enter the esterification separation tower for vapor-liquid separation; and tetrabutyl titanate, the catalyst (Ⅲ), is added. The esterified product A obtained from the reaction kettle A and the esterified product B obtained from the reaction kettle B are sent to the second esterification kettle for further reaction to obtain oligomers. Among them, the molar ratio of the esterified product A to the esterified product B is 1:1.2, and the dosage of the catalyst (Ⅲ) is 0.9% of the total amount of the esterified product A and the esterified product B. The operating conditions are: 240 °C and -0.04 MPaG, and the reaction residence time is 3.2 h. The oligomers are then pumped into the pre-polycondensation kettle for pre-polycondensation. The operating conditions of the pre-polycondensation kettle are: 240 °C and 1 - 10 kPaA, and the reaction residence time is 5 h. The polymer obtained from the pre-polycondensation kettle is sent to the final polycondensation kettle for further reaction to obtain the PBST product. The operating conditions are: 245 °C and 100 PaA, and the reaction residence time is 10 h.

[0092] Using the above preparation method, the viscosity of the prepared PBST is 3,000 - 600,000 CP, and the melt index is 2 - 10 g / 10 min.

Claims

1. A method for continuously preparing PBST, comprising: Under the condition that a part of 1,4 - butanediol enters from the top of the reactive distillation column, a mixed slurry of terephthalic acid and another part of 1,4 - butanediol, and a mixed slurry of succinic acid and another part of 1,4 - butanediol are respectively reacted in the reactive distillation column to obtain esterified product A and esterified product B, and then the esterified product A and esterified product B are subjected to a polymerization reaction to obtain PBST.

2. The method according to claim 1, characterized in that, the production method comprises the following steps: (1) The slurry A of terephthalic acid and 1,4 - butanediol (Ⅰ) is continuously transported by a metering pump to the reactive distillation column A for an esterification reaction, and at the same time, 1,4 - butanediol (Ⅱ) enters the reactive distillation column A from the top of the reactive distillation column, and the reaction obtains esterified product A; (2) The slurry B of succinic acid and 1,4 - butanediol (Ⅲ) is continuously transported by a metering pump to the reactive distillation column B for an esterification reaction, and at the same time, 1,4 - butanediol (Ⅳ) enters the reactive distillation column B from the top of the reactive distillation column, and the reaction obtains esterified product B; (3) The esterified product A and esterified product B are sent to a tower reactor for further polymerization reaction to obtain PBST.

3. The method according to claim 2, characterized in that, in the step (1): the molar ratio of the terephthalic acid to 1,4 - butanediol (Ⅰ) is 1:(1.05 - 1.5), preferably 1:(1.1 - 1.2); and / or, the molar ratio of 1,4 - butanediol (Ⅰ) to 1,4 - butanediol (Ⅱ) is 1:(0.1 - 2), preferably 1:(0.4 - 1.2); and / or, in the reactive distillation column A, the operating temperature of the reaction section is 170 - 260 °C, preferably 190 - 240 °C; and / or, in the reactive distillation column A, the operating pressure of the reaction section is - 0.08 - + 0.1 MPaG, preferably - 0.06 - + 0.05 MPaG; and / or, in the reactive distillation column A, the operating conditions at the top of the rectifying section are: temperature 60 - 150 °C, pressure - 0.1 - + 0.1 MPaG; preferably, temperature 70 - 120 °C, pressure - 0.08 - + 0.05 MPaG; and / or, in the reactive distillation column A, the operating conditions at the bottom of the rectifying section are: temperature 150 - 230 °C, pressure - 0.08 - + 0.1 MPaG; preferably, temperature 180 - 220 °C, pressure - 0.06 - + 0.05 MPaG; and / or, the reaction residence time in the reactive distillation column A is 2 - 10 h, preferably 3.5 - 6.5 h; and / or, a catalyst (Ⅰ) is also added in the esterification reaction, and the catalyst (Ⅰ) is preferably selected from at least one of titanium - based catalysts and rare - earth catalysts; and / or, the dosage of the catalyst (Ⅰ) is preferably 0.1 - 5 wt% of the total amount of 1,4 - butanediol (Ⅰ) and 1,4 - butanediol (Ⅱ), more preferably 0.5 - 3.0 wt%.

4. The method according to claim 2, characterized in that, in the step (2): The molar ratio of the described succinic acid and 1,4-butanediol (Ⅲ) is 1:(1.05 - 1.5), preferably 1:(1.1 - 1.2); and / or, The molar ratio of the described 1,4-butanediol (Ⅲ) and 1,4-butanediol (Ⅳ) is 1:(0.1 - 2.2), preferably 1:(0.4 - 1.1); and / or, In the described reactive distillation column B, the operating temperature of the reaction section is 170 - 260 °C, preferably 190 - 240 °C; and / or, In the described reactive distillation column B, the operating pressure of the reaction section is -0.08 to +0.1 MPaG, preferably -0.06 to +0.05 MPaG; and / or, In the described reactive distillation column B, the operating conditions at the top of the rectification section are: temperature 60 - 150 °C, pressure -0.1 to +0.1 MPaG; preferably, temperature 70 - 120 °C, pressure -0.08 to +0.05 MPaG; and / or, In the described reactive distillation column B, the operating conditions at the bottom of the rectification section are: temperature 150 - 230 °C, pressure -0.08 to +0.1 MPaG; preferably, temperature 180 - 220 °C, pressure -0.06 to +0.05 MPaG; and / or, The reaction residence time in the described reactive distillation column B is 2 - 10 h, preferably 3 - 6 h; and / or, In the described esterification reaction, a catalyst (Ⅱ) is further added. The described catalyst (Ⅱ) is preferably selected from at least one of titanium-based catalysts and rare earth catalysts; and / or, the dosage of the catalyst (Ⅱ) is preferably 0.1 - 4.5 wt% of the total amount of 1,4-butanediol (Ⅲ) and 1,4-butanediol (Ⅳ), more preferably 0.5 - 3.5 wt%.

5. According to the method described in claim 2, It is characterized in that, In the described step (3): The molar ratio of the described esterified product A and esterified product B is 1:(0.8 - 1.3), preferably 1:(0.9 - 1.1); and / or, The described tower reactor includes multiple reaction stages. Among them, the reaction conditions for the first stage in the upper stage are: reaction temperature 210 - 270 °C, reaction pressure 100 Pa - 90 kPa, reaction residence time 1 - 7 h; and / or, the reaction conditions for the second stage in the middle stage are: reaction temperature 220 - 300 °C, reaction pressure 100 Pa - 90 kPa, reaction residence time 2 - 10 h; and / or, the reaction conditions for the last stage are: reaction temperature 220 - 270 °C, reaction pressure 50 - 1000 Pa, reaction residence time 3 - 15 h; preferably, the reaction conditions for the first stage in the upper stage are: reaction temperature 220 - 260 °C, reaction pressure 500 Pa - 80 kPa, reaction residence time 2 - 5 h; and / or, the reaction conditions for the second stage in the middle stage are: reaction temperature 230 - 270 °C, reaction pressure 500 Pa - 80 kPa, reaction residence time 3 - 8 h; and / or, the reaction conditions for the last stage are: reaction temperature 230 - 260 °C, reaction pressure 60 - 600 Pa, reaction residence time 5 - 13 h; and / or, In the polymerization reaction, a catalyst (III) is further added. The catalyst (III) is preferably at least one selected from titanium-based catalysts and rare earth catalysts; and / or, the dosage of the catalyst (III) is preferably 0.05-5 wt% of the total amount of esterified product A and esterified product B, more preferably 0.1-3.5 wt%.

6. An apparatus for continuously preparing PBST, which uses the method according to any one of claims 1-5 to continuously prepare PBST. Preferably, the apparatus comprises: Reactive distillation column A and reactive distillation column B connected in parallel, and a tower reactor connected to the bottoms of reactive distillation column A and reactive distillation column B through pipelines.

7. The apparatus according to claim 6, characterized in that the bottom material outlet pipelines of reactive distillation column A and reactive distillation column B are connected and communicated and connected to the material inlet of the tower reactor; and / or, the reactive distillation column A and reactive distillation column B each comprise an upper rectification section and a lower reaction section; preferably, the height ratio of the rectification section to the reaction section is 1:(0.1-0.6), preferably 1:(0.15-0.4); and / or, in the rectification section, an exhaust gas discharge outlet is arranged at the top of the rectification section, a 1,4-butanediol inlet is arranged at the upper side line of the rectification section, and an external discharge outlet for the material containing 1,4-butanediol is arranged at the lower side line of the rectification section; more preferably, the 1,4-butanediol inlet is arranged at 0.1%-20% from top to bottom of the rectification section, and the external discharge outlet for the material containing 1,4-butanediol is arranged at 0.1%-20% from bottom to top of the rectification section; and / or, the rectification section comprises an upper packing section and a lower tray section. Preferably, the height of the upper packing section is 20-90% of the total height of the rectification section, more preferably 40-70%; and / or, the number of trays in the lower tray section is 1-20, more preferably 4-8; and / or, the reflux molar percentage of the rectification section is 0.5-3, more preferably 1-2; and / or, in the reaction section, a material inlet is arranged at the side line of the reaction section, and a material outlet is arranged at the bottom of the reaction section; more preferably, in the reaction section, the material inlet is arranged at the head of the reaction section or at 0-1 / 2 from top to bottom of the side line of the reaction section; and / or, a stirring device is arranged in the reaction section; and / or, a heating internal coil is arranged in the tower kettle of the reaction section; and / or, a jacket or an external half-pipe temperature control device is arranged outside the reaction section.

8. The apparatus according to claim 6, characterized in that the tower reactor is a segmented tower reactor. Preferably, the tower reactor comprises at least three reactors from top to bottom. More preferably, the first reactor in the upper section and the second reactor in the middle section are connected and communicated to form a closed reaction unit. The bottom material outlet of the second reactor is connected to the material inlet of the next reactor through a pipeline, and a PBST product external discharge pipeline is arranged at the bottom of the last reactor.

9. The apparatus according to claim 8, characterized in that in the tower reactor: the material inlet of the tower reactor is arranged at the top of the first reactor or at 0-1 / 2 from top to bottom of the side line of the first reactor, preferably at the top; and / or, A gas-phase discharge outlet is provided on the side line of the second-stage reactor. Preferably, the gas-phase discharge outlet is provided at the top of the second-stage reactor or at the 0 to 1 / 2 position from top to bottom of the side line of the second-stage reactor, more preferably at the 1 / 5 to 1 / 3 position; and / or, The last-stage reactor includes an upper cylindrical barrel and a lower inverted cone, and the diameter of the upper cylindrical barrel is the same as the diameter of the upper end of the lower inverted cone; A polymer outlet is provided at the bottom of the tower reactor. Preferably, a material pump is provided on the polymer outlet pipeline.

10. The apparatus according to claim 9, characterized in that in the last-stage reactor: the cone angle of the lower inverted cone is 15 to 120°, more preferably 30 to 100°; and / or, the height of the upper cylindrical barrel is 1 to 12 times the diameter of the upper cylindrical barrel, more preferably 1.2 to 6 times; and / or, a distributor is provided in the upper cylindrical barrel, preferably a grid distributor; more preferably, the distributor is provided at the 0 to 1 / 2 position from bottom to top of the upper cylindrical barrel; and / or, a gas-phase discharge outlet is provided on the side line at the lower end of the upper cylindrical barrel. Preferably, the gas-phase discharge outlet is provided above the distributor; and / or, the gas-phase discharge outlet is provided at the 1 / 2 to 7 / 8 position from top to bottom of the side line of the upper cylindrical barrel, more preferably at the 2 / 3 to 3 / 4 position.

11. A PBST is prepared by using the method for continuously preparing PBST according to any one of claims 1 to 5 or the apparatus for continuously preparing PSBT according to any one of claims 6 to 10.

12. The PBST according to claim 10, characterized in that the melt index of the prepared PBST is 0.1 to 50 g / 10 min, and the viscosity is 2,000 to 1,500,000 cP.

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