A method for producing polyaromatic-carbonic-aliphatic copolyester

Abstract

This invention belongs to the field of polymer materials technology, specifically relating to a method for producing polyaromatic-carbonic-aliphatic copolyester, comprising the following steps: mixing an aromatic diacid and an aliphatic diol and feeding them into a first esterification reactor, adding an esterification catalyst to carry out an esterification reaction to obtain an esterification product; mixing the aliphatic diol evenly and feeding it into a second esterification reactor, then adding diester carbonate and an esterification catalyst to the second esterification reactor to react and obtain an esterification product; feeding the esterification product into a monomer removal reactor to obtain a monomer removal product; mixing the esterification product and the monomer removal product with a polycondensation catalyst and a stabilizer, and after shear homogenization, feeding it into a pre-polycondensation reactor to react and obtain a pre-polycondensation product; feeding the pre-polycondensation product into a final polycondensation reactor to react and obtain a copolymer, and then water-cooling and granulating to obtain the copolyester product. The production method provided by this invention can shorten the final polycondensation reaction time and improve the weight-average molecular weight and mechanical strength of the prepared copolyester.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a method for producing polyaromatic-carbonic-aliphatic copolyester. Background Technology

[0002] With increasing societal emphasis on environmental protection, biodegradable plastics are gaining wider application. Among them, poly(butylene terephthalate-adipate-butanediol) copolyester (PBAT) is a widely recognized biodegradable plastic with excellent overall performance, suitable for applications such as blown film bag making and injection molding. However, PBAT's poor barrier properties and low mechanical strength limit its application development in the packaging field.

[0003] Aliphatic polycarbonates are also biodegradable plastics with excellent degradation performance, good hydrolysis resistance, excellent flexibility, and low water vapor permeability. In contrast, the transesterification method uses carbonate diesters and aliphatic diols (or polyols) as raw materials for synthesis, which has the advantages of wide availability of raw materials, diverse structures, and environmental friendliness. Patent publication number CN112280028A reports a method for preparing high molecular weight polybutylene carbonate (PBC, belonging to aliphatic polycarbonates), but polybutylene carbonate has a low melting point, usually between 40 and 60°C, and a slow crystallization rate (the crystallization time of high molecular weight PBC melt at room temperature can be as long as 1 hour), which greatly limits its application.

[0004] Numerous researchers have conducted in-depth studies on the structure-activity relationship of aromatic-aliphatic polycarbonates. Patent CN103265689A introduces aromatic monomers such as terephthalic acid and isophthalic acid into the polycarbonate backbone, employing a stepwise esterification method to prepare a high-performance aromatic-carbonate-aliphatic copolyester. The effects of transesterification catalysts such as metal hydroxides, metal oxides, alkoxymetal compounds, metal carbonates, metal bicarbonates, metal halides, metal acetates, organic acids, tin-based organic compounds, and titanium-based organic compounds on the molecular weight of the product were investigated. However, the copolyester obtained by this method has a long final polycondensation time, requiring approximately 20 hours. This would lead to high energy consumption, high production costs, and poor economic efficiency in large-scale industrial production. Therefore, how to further simplify the production steps of aromatic-carbonate-aliphatic copolyesters, shorten the polymerization time, improve product yield, reduce raw material consumption, and provide copolymers with better performance are urgent technical problems to be solved. Summary of the Invention

[0005] In view of the technical problems of long final polycondensation time and poor performance in the existing copolyester production methods mentioned in the background art, the present invention provides a production method for polyaromatic-carbonic-aliphatic copolyester. Through innovative production process, the final polycondensation reaction time can be shortened and the weight-average molecular weight and mechanical strength of the prepared copolyester can be improved.

[0006] This invention provides a method for producing polyaromatic-carbonic-aliphatic copolyester, comprising the following steps:

[0007] S1. Aromatic dicarboxylic acid and aliphatic diol are mixed to form a homogeneous slurry, which is then fed into the first esterification reactor and an esterification catalyst is added to carry out the esterification reaction to obtain the esterification product. The molar ratio of aromatic dicarboxylic acid to aliphatic diol in the homogeneous slurry is 1:1.5 to 1:3.

[0008] S2. After the aliphatic diols are mixed evenly, they are fed into the second esterification reactor. Then, diester carbonate and esterification catalyst are added to the second esterification reactor to carry out the esterification reaction, and the esterification product is obtained. The esterification product is sent to the monomer removal reactor to remove small molecules and oligomers, and the monomer removal product is obtained. The molar ratio of diester carbonate to aliphatic diol is 1.5:1 to 3:1. During the esterification reaction in the second esterification reactor, the content of diester carbonate is 20% to 80% of the distillate. The diester carbonate is added in batches.

[0009] S3. The esterification product obtained in S1 and the demonopolymerization product obtained in S2 are mixed with polycondensation catalyst and stabilizer. After shearing and homogenization, the mixture is fed into a pre-polycondensation reactor to react and obtain a pre-polycondensation product. The pre-polycondensation product is then fed into a final polycondensation reactor to react and obtain a copolymer. The copolymer is then fed into a thickening reactor or a dynamic mixing reactor to react and then water-cooled and granulated to obtain a copolyester product.

[0010] Furthermore, the aliphatic diols include one or more of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2,4-trimethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-tert-butyl-1,3-propanediol, and 2,2,4-trimethyl-1,6-hexanediol;

[0011] The carbonate diester includes one or more of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, diphenyl carbonate, xylene carbonate, and dinaphthalene carbonate;

[0012] The aromatic dicarboxylic acid includes one or more of terephthalic acid, terephthalic acid, naphthalenecyclodicarboxylic acid, furanyl dicarboxylic acid, and six-membered cyclodicarboxylic acid.

[0013] Furthermore, the esterification catalyst and transesterification catalyst include one or more of acetate, titanium compounds, antimony compounds, germanium compounds and rare earth compounds;

[0014] The polycondensation catalyst includes one or more of titanium-based compounds, antimony-based compounds, germanium-based compounds, tin-based compounds, and rare earth compounds;

[0015] The stabilizer includes one or a mixture of several of the following: trimethyl phosphate, triethyl phosphate, tripropyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, tripropyl phosphite, triphenyl phosphite, phosphorous acid, or phosphoric acid.

[0016] Furthermore, in step S1, the amount of esterification catalyst used is 0.001 to 5 wt% of the sum of the masses of the aromatic dicarboxylic acid and the aliphatic diol; the reaction temperature of the first esterification reactor is 160 to 250°C, the pressure is 10 to 30 kPa, and the reaction time is 1 to 10 h.

[0017] Furthermore, in step S2, the amount of esterification catalyst used is 0.001–5 wt% of the sum of the mass of dimethyl carbonate and aliphatic diol; the reaction temperature of the second esterification reactor is 90–200°C, the reaction time is 1–30 h, and the content of diester in the transesterification reaction of the second esterification reactor is 20–80% of the reactants; the reaction temperature of the demonochemical reactor is 120–200°C, the pressure is 10–70 kPa, and the reaction time is 0–6 h.

[0018] Furthermore, in step S3, the amount of polycondensation catalyst used is 0.005–5 wt% of the sum of the weights of the monopolymerization product and the esterification product, and the amount of stabilizer used is 0.001–1 wt% of the sum of the weights of the monopolymerization product and the esterification product; the reaction temperature in the prepolymerization reactor is 160–230°C, the pressure is 70–90 kPa, and the reaction time is 2–8 h; the reaction temperature in the final polycondensation reactor is 180–230°C, the pressure is 90–99 kPa, and the reaction time is 0–8 h.

[0019] Furthermore, in step S3, the reaction temperature in the thickening reactor is 180–230°C, the pressure is 5–1000 Pa, and the reaction time is 0–8 h; the reaction in the dynamic mixing reactor is at a temperature of 160–240°C, a pressure of 90–100 kPa, and a residence time of 0–60 min.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. This invention adds a single-molecule removal reactor to the reaction process, which can better remove small-molecule oligomers and other polymers generated during the esterification reaction, improve the esterification rate, facilitate the adjustment of the esterified molecule configuration and distribution, and promote the synthesis of high molecular weight polymers, ultimately achieving a product molecular weight of 88,800 g / mol. Simultaneously, this invention uses a thickening reactor or a dynamic mixing reactor, increasing the devolatilization area and rapidly increasing the degree of polymerization, enabling the product molecular weight to reach a maximum of 124,900 g / mol.

[0022] 2. In the transesterification reaction, the present invention uses the method of adding diester carbonate to aliphatic diol in batches, which reduces the consumption of diester carbonate raw material, is conducive to the forward reaction, and is beneficial to the synthesis of high molecular weight polymers. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the steps of the method for producing polyaromatic-carbonic-aliphatic copolyester in Example 1 of the present invention.

[0024] Figure 2 This is a flowchart illustrating the steps of the method for producing polyaromatic-carbonic-aliphatic copolyester in Embodiment 2 of the present invention.

[0025] Figure 3 This is a flowchart illustrating the steps of the production method of polyaromatic-carbonic-aliphatic copolyester in Embodiment 3 of the present invention. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation, but can be combined with each other to achieve better technical effects.

[0027] This invention provides a method for producing polyaromatic-carbonic-aliphatic copolyester, wherein the production apparatus used in the method is as shown in the attached figure. Figure 1 As shown in Figure 3, the system includes a first mixing tank, a second mixing tank, a first esterification reactor, a second esterification reactor, a monomer removal reactor, a prepolymerization reactor, a final polymerization reactor, a thickening reactor, and a dynamic mixing reactor. The first mixing tank and the first esterification reactor are connected via pipelines, and the second mixing tank is sequentially connected to the second esterification reactor and the monomer removal reactor via pipelines. In this invention, the esterification reactor employs a distillation column with reflux, which allows for adjustment of the ratio of diester to aliphatic diols, efficient utilization of raw materials, and facilitates the adjustment of molecular configuration and distribution, synthesis of high molecular weight polymers, reduction of by-product yield, improvement of product yield, optimization of the esterification process, and energy saving and consumption reduction.

[0028] The outlets of the first esterification reactor and the monomer removal reactor are connected to the prepolymerization reactor via a conveying pipeline. An injection system and a shear homogenizing mixer are installed on the conveying pipeline. The injection system is used to inject the polycondensation catalyst and stabilizer. The shear homogenizing mixer overcomes the short residence time of oligomers and additives in the pipeline, ensuring sufficient mixing time between the additives and oligomers. In this invention, the shear homogenizing mixer is a high-shear homogenizing pump dynamic mixer, a homogenizer static mixer, or a combination of both.

[0029] The prepolymerization reactor is connected to the final polymerization reactor via a pipeline. The monomer removal reactor, prepolymerization reactor, and final polymerization reactor are also connected to a vacuum system for adjusting the vacuum level during the reaction. In this invention, the final polymerization reactor is a horizontal film-stretching reactor, which effectively increases the devolatilization area, facilitating the removal of small molecules and resulting in products with good appearance and medium to high molecular weight.

[0030] This invention can adjust the molecular weight of the copolyester to be prepared as required, as shown in the attached figure. Figure 1 In one method, the final polycondensation reactor is connected to an underwater pelletizing system, which can directly produce copolyester products with a weight-average molecular weight of 70,000 to 90,000 g / mol.

[0031] As attached Figure 2 Or attached Figure 3 In one embodiment, a thickening reactor or a dynamic mixing reactor is connected to the outlet of the final polycondensation reactor, and an underwater pelletizing system is installed after the thickening reactor or dynamic mixing reactor. The weight-average molecular weight of the produced copolyester product is 110,000~130,000 g / mol.

[0032] This invention provides a method for producing a polyaromatic-carbonic-aliphatic copolyester, comprising the following steps:

[0033] S1. Aromatic dicarboxylic acid, aliphatic diol and esterification catalyst are mixed to form a uniform slurry, which is then fed into the first esterification reactor for esterification reaction to obtain esterification product.

[0034] Specifically, aromatic diacids and aliphatic diols are weighed in a molar ratio of 1:1 to 1:3 and added to the first slurry mixing tank. Then, 0.001 to 5 wt% of the total weight of the aromatic diacids and aliphatic diols are weighed and added to the first slurry mixing tank. After mixing to form a homogeneous slurry, it is sent to the first esterification reactor for reaction. The reaction temperature in the first esterification reactor is set at 160 to 250°C, the pressure at 10 to 30 kPaA, and the reaction is continued for 1 to 10 hours to obtain the esterification product.

[0035] The aliphatic diols in this invention include one or more of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2,4-trimethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-tert-butyl-1,3-propanediol, and 2,2,4-trimethyl-1,6-hexanediol. The aromatic dicarboxylic acids include terephthalic acid, naphtholic dicarboxylic acid, furanyl dicarboxylic acid, and hexacyclic dicarboxylic acid.

[0036] The esterification catalyst includes one or more of acetate, titanium compounds, antimony compounds, germanium compounds, and rare earth compounds, wherein the acetate is one or more of cobalt acetate, manganese acetate, magnesium acetate, calcium acetate, zinc acetate, lithium acetate, aluminum acetate, and sodium acetate; the titanium compounds are one or more of tetrabutyl titanate, isopropyl titanate, titanium dioxide, tetraisooctyl titanate, potassium titanium oxalate, and titanium glycolate; the antimony compounds are one or more of antimony trioxide, antimony acetate, and antimony glycolate; the germanium compounds are one or two of germanium dioxide and germanium chloride; the tin compounds are one or more of stannous octoate, stannous oxalate, butylstannic acid, monobutyltin oxide, and dibutyldiethyloctyl ester; and the rare earth compounds are one or more of lanthanum chloride, hafnium chloride, rubidium chloride, yttrium chloride, lanthanum acetylacetone, hafnium acetylacetone, rubidium acetylacetone, and yttrium acetylacetone.

[0037] S2. After the aliphatic diol and the transesterification catalyst are mixed evenly, they are fed into the second esterification vessel. Then, diester carbonate is added to the second esterification vessel to carry out the transesterification reaction to obtain the transesterification product. The transesterification product is then sent to the demonomerization vessel to remove small molecules and oligomers to obtain the demonomerization product.

[0038] Specifically, raw materials, dicarbonate and aliphatic diol, are weighed at a molar ratio of 1:1.5 to 3:1. The aliphatic diol is then added to a second mixing tank. Next, 0.001 to 5 wt% of the total weight of the raw materials, dicarbonate and aliphatic diol, of transesterification catalyst is added to the second mixing tank and mixed thoroughly before being transferred to a second esterification reactor. The reaction temperature in the second esterification reactor is set at 90–200°C, and the reaction pressure is atmospheric pressure. Dicarbonate is added to the second esterification reactor in portions during the reaction, controlling the content of dicarbonate during the transesterification reaction in the second esterification reactor to be 20–80% of the total reactant mass to facilitate the forward reaction. After the reaction, the transesterification product is obtained and sent to a demonomerization reactor to remove small molecules and oligomers. The reaction temperature in the demonomerization reactor is set at 120–200°C, the reaction pressure at 10–70 kPa, and the reaction time at 0–6 h. After the reaction, the demonomerization product is obtained.

[0039] In this invention, the aliphatic diol is the same as that in step S1, the transesterification catalyst is the same as that in step S1, and the carbonate diester includes one or more of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, diphenyl carbonate, dimethyl carbonate, and dinaphthalene carbonate.

[0040] S3. The esterification product obtained in S1 and the demonopolymerization product obtained in S2 are mixed with polycondensation catalyst and stabilizer. After shearing and homogenization, the mixture is fed into a pre-polycondensation reactor to react and obtain a pre-polycondensation product. The pre-polycondensation product is then fed into a final polycondensation reactor to react and obtain a copolymer. The copolymer is then directly water-cooled and granulated, or the copolymer is fed into a thickening reactor and / or a dynamic mixing reactor to react and then water-cooled and granulated to obtain a copolyester product.

[0041] Specifically, the esterification product and the demonopolymerization product are fed into the prepolymerization reactor via a conveying pipeline. A polycondensation catalyst and stabilizer are added to the pipeline. The amount of polycondensation catalyst is 0.005–5 wt% of the sum of the weights of the demonopolymerization product and the esterification product, and the amount of stabilizer is 0.001–1 wt% of the sum of the weights of the demonopolymerization product and the esterification product. The esterification product, demonopolymerization product, polycondensation catalyst, and stabilizer in the conveying pipeline pass through a shear homogenizing mixer. The shear homogenizing mixer has a shear rate of 300–3000 rad / s and a shearing time of 5–60 s. The mixture then enters the prepolymerization reactor to react and obtain the prepolymerization product. The shear homogenizing mixer ensures thorough mixing of the raw materials, catalyst, and stabilizer while maintaining liquefaction without vaporization. This results in a uniform distribution of functional groups on the polyester backbone, promoting a more complete homogeneous plug flow reaction and ensuring the production of a high-quality copolyester product. The reaction temperature of the prepolymerization reactor is 160-230℃, the pressure is 70-90kPa, the reaction time is 2-8h, and the weight-average molecular weight of the prepolymerization product is 30000-50000g / mol.

[0042] The prepolymerization product is then fed into the final polymerization reactor to continue the reaction and obtain the copolymer. The reaction temperature of the final polymerization reactor is 180-230℃, the pressure is 90-99kPaA, and the reaction time is 0-8h.

[0043] After obtaining the copolymer, the copolymer is post-processed to obtain the copolyester product. Post-processing includes either direct water-cooled granulation or reacting the copolymer in a thickening reactor and / or a dynamic mixing reactor followed by water-cooled granulation. The copolyester product obtained by direct water-cooled granulation has a weight-average molecular weight of 70,000–90,000 g / mol, while the copolyester product obtained after reaction in a thickening reactor and / or a dynamic mixing reactor has a weight-average molecular weight of 110,000–130,000 g / mol. It should be noted that chain extenders need to be added when reacting in a dynamic mixing reactor. These chain extenders include diisocyanates, dianhydrides, diacyl chlorides, diepoxides, and bis(2-oxazoline), specifically including 1,6-hexamethylene diisocyanate, phenylene diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene-1,6-diisocyanate, etc.; maleic anhydride, succinic anhydride, acetic anhydride, phthalic anhydride, benzoyl tetrahydride, etc.; succinyl chloride, adipic chloride, sebacyl chloride, etc.; ethylene oxide, propylene oxide, trihydroxypropane, etc.; and 2,2-bis(2-oxazoline), etc.

[0044] The polycondensation catalyst in this invention includes one or more of titanium-based compounds, antimony-based compounds, germanium-based compounds, tin-based compounds, and rare earth compounds, with the specific compounds being the same as those in the esterification catalysts described above.

[0045] Stabilizers include one or a mixture of several of the following: trimethyl phosphate, triethyl phosphate, tripropyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, tripropyl phosphite, triphenyl phosphite, phosphorous acid, or phosphoric acid.

[0046] Example 1

[0047] This embodiment provides a method for producing a polyaromatic-carbonic-aliphatic copolyester, including the following steps:

[0048] S1. Terephthalic acid (PTA) and 1,4-butanediol (BDO) are mixed in a first mixing tank at a molar ratio of 1:1.8. The mixture is then fed into the first esterification reactor at a rate of 560 kg / h. Zinc acetate catalyst is added to the first esterification reactor at a rate of 1.5 kg / h. The temperature of the first esterification reactor is controlled at 200°C and the pressure at 20 kPa. The reaction is allowed to proceed for 6 hours. The water in the reaction product is then removed to obtain the esterified product.

[0049] S2. Weigh BDO and dimethyl carbonate (DMC) at a molar ratio of 1:2.5. Add BDO to the second mixing tank and mix. Then, feed the mixture into the second esterification reactor at a rate of 340 kg / h. Add DMC to the second esterification reactor in portions and add magnesium acetate catalyst at a rate of 1 kg / h. Control the reaction temperature in the second esterification reactor at 160°C and the reaction pressure at atmospheric pressure. Hold the reaction for 20 hours, maintaining the DMC content in the azeotrope in the second esterification reactor at 20%–80% during this period. The reaction yields transesterification products. Continuously transfer the transesterification products to a demonolysis reactor. Control the reaction temperature in the demonolysis reactor at 180°C and the pressure at 30 kPaA. Hold the reaction for 2 hours to obtain the demonolysis products.

[0050] S3. The esterification product and the demonopolymerization product are continuously fed into the prepolymerization reactor through a conveying pipeline at rates of 560 kg / h and 340 kg / h, respectively. Ethylene glycol antimony catalyst and triphenyl phosphite stabilizer are injected into the conveying pipeline at a rate of 0.2 kg / h. The esterification product, demonopolymerization product, ethylene glycol antimony catalyst, and triphenyl phosphite stabilizer are then fed into the prepolymerization reactor via a high-shear homogenization pump. The temperature in the prepolymerization reactor is set at 180℃ and the pressure at 90 kPa. After 3 hours of prepolymerization, the prepolymerization product is obtained. This prepolymerization product is then transferred to the final polymerization reactor, where the temperature is 200℃ and the pressure is 200 Pa. After 8 hours of reaction, the copolymer melt is obtained. This melt is then processed through a water-cooled granulation device to obtain the copolymer product, which is injection-grade chips.

[0051] Example 2

[0052] This embodiment provides a method for producing a polyaromatic-carbonic-aliphatic copolyester, including the following steps:

[0053] S1. Terephthalic acid (PTA) and 1,2-butanediol are mixed in a molar ratio of 1:2.2 in a first mixing tank to form a slurry. The slurry is then fed into a first esterification reactor at a rate of 560 kg / h. Zinc acetate catalyst is added to the first esterification reactor at a rate of 1.5 kg / h. The temperature of the first esterification reactor is controlled at 220°C and the pressure at 25 kPa. The reaction is allowed to proceed for 5 hours. The water in the reaction product is then removed to obtain the esterified product.

[0054] S2. Weigh 1,2-butanediol and diethyl carbonate at a molar ratio of 1:2.1. Add BDO to the second mixing tank and then feed it into the second esterification reactor at a rate of 340 kg / h. Add DMC in portions to the second esterification reactor and add magnesium acetate catalyst at a rate of 1 kg / h. Control the reaction temperature in the second esterification reactor at 160°C and the reaction pressure at atmospheric pressure. Hold the reaction for 20 hours, maintaining the DMC content in the azeotrope in the second esterification reactor at 20%–80% during this period. The reaction yields the transesterification product, which is continuously fed to the demonolysis reactor. Control the reaction temperature in the demonolysis reactor at 160°C and the pressure at 40 kPa. Hold the reaction for 3 hours to obtain the demonolysis product.

[0055] S3. The esterification product and the demonopolymerization product are continuously fed into the prepolymerization reactor via a conveying pipeline at rates of 560 kg / h and 340 kg / h, respectively. Ethylene glycol antimony catalyst and triphenyl phosphite stabilizer are injected into the conveying pipeline at a rate of 0.2 kg / h. The esterification product, demonopolymerization product, ethylene glycol antimony catalyst, and triphenyl phosphite stabilizer are then fed into the prepolymerization reactor via a high-shear homogenization pump. The temperature in the prepolymerization reactor is set at 180℃ and the pressure at 90 kPa. After 3 hours of polycondensation, the prepolymerization product is obtained. This prepolymerization product is then transferred to the final polycondensation reactor, where the temperature is set at 200℃ and the pressure at 200 Pa. After 1.5 hours of reaction, the copolymer melt is obtained. The copolymer melt is then transferred to a thickening reactor, where the pressure is set at 50 Pa and the temperature at 200℃ for continuous thickening for 4 hours, yielding the copolymer melt. After passing through a water-cooled granulation device, the copolymer product is obtained as blow-molded chips.

[0056] Example 3

[0057] This embodiment provides a method for producing a polyaromatic-carbonic-aliphatic copolyester, including the following steps:

[0058] S1. Terephthalic acid and 1,4-butanediol are mixed in a molar ratio of 1:2.5 in the first mixing tank to form a slurry, which is then fed into the first esterification reactor at a rate of 560 kg / h. Zinc acetate catalyst is added to the first esterification reactor at a rate of 1.5 kg / h. The temperature of the first esterification reactor is controlled at 190°C and the pressure at 23 kPa. The reaction is held for 6 hours, and the water in the reaction product is removed to obtain the esterified product.

[0059] S2. Weigh 1,4-butanediol and dimethyl carbonate (DMC) at a molar ratio of 1:1.7. Add BDO to the second mixing tank and then feed it into the second esterification reactor at a rate of 340 kg / h. Add DMC to the second esterification reactor in portions and add magnesium acetate catalyst at a rate of 1 kg / h. Control the reaction temperature in the second esterification reactor at 160°C and the reaction pressure at atmospheric pressure. Hold the reaction for 20 hours, maintaining the DMC content in the azeotrope in the second esterification reactor at 20%–80% during this period. The reaction yields the transesterification product, which is continuously fed to the demonolysis reactor. Control the reaction temperature in the demonolysis reactor at 150°C and the pressure at 50 kPa. Hold the reaction for 3 hours to obtain the demonolysis product.

[0060] S3. The esterification product and the demonopolymerization product are continuously fed into the prepolymerization reactor via a conveying pipeline at rates of 560 kg / h and 340 kg / h, respectively. Ethylene glycol antimony catalyst and triphenyl phosphite stabilizer are injected into the conveying pipeline at a rate of 0.2 kg / h. The esterification product, demonopolymerization product, ethylene glycol antimony catalyst, and triphenyl phosphite stabilizer are then fed into the prepolymerization reactor via a high-shear homogenizing pump. The temperature in the prepolymerization reactor is set at 180℃ and the pressure at 90 kPa. After 3 hours of polycondensation, the prepolymerization product is obtained. This prepolymerization product is then transferred to the final polycondensation reactor, where the temperature is set at 190℃ and the pressure at 90 kPa. After 2 hours of reaction, the copolymer melt is obtained. The copolymer melt is then transferred to a dynamic mixing reactor, where a chain extender is added. The dynamic mixing reactor is set at a pressure of 100 kPa and a temperature of 190℃, and the reaction is continued for 4 hours to obtain the copolymer melt. After passing through a water-cooled granulation device, the copolymer product is obtained as blow-molded chips.

[0061] Comparative Example 1

[0062] The difference between this comparative example and Example 1 lies in the different reaction parameters. Specifically, this comparative example includes the following steps:

[0063] S1. Terephthalic acid (PTA) and 1,4-butanediol (BDO) are mixed in a 1:1 molar ratio in a first mixing tank to form a slurry. The slurry is then fed into a first esterification reactor at a rate of 560 kg / h. Zinc acetate catalyst is added to the first esterification reactor at a rate of 1.5 kg / h. The temperature of the first esterification reactor is controlled at 200°C and the pressure at 20 kPa. The reaction is allowed to proceed for 6 hours. Water is removed from the reaction product to obtain the esterified product.

[0064] S2. Weigh BDO and dimethyl carbonate (DMC) at a molar ratio of 1:3.5. Add BDO to the second mixing tank and mix. Then, feed the mixture into the second esterification reactor at a rate of 340 kg / h. Add DMC to the second esterification reactor in portions and add magnesium acetate catalyst at a rate of 1 kg / h. Control the reaction temperature in the second esterification reactor at 160°C and the reaction pressure at atmospheric pressure. Hold the reaction for 20 hours. The resulting transesterification product is continuously transferred to a demonotransfer reactor. Control the reaction temperature in the demonotransfer reactor at 180°C and the pressure at 30 kPa. Hold the reaction for 2 hours to obtain the demonotransfer product.

[0065] S3. The esterification product and the demonopolymerization product are continuously fed into the prepolymerization reactor through a conveying pipeline at rates of 560 kg / h and 340 kg / h, respectively. Ethylene glycol antimony catalyst and triphenyl phosphite stabilizer are injected into the conveying pipeline at a rate of 0.2 kg / h. The esterification product, demonopolymerization product, ethylene glycol antimony catalyst, and triphenyl phosphite stabilizer are then fed into the prepolymerization reactor via a high-shear homogenization pump. The temperature in the prepolymerization reactor is set at 180℃ and the pressure at 90 kPa. After 3 hours of prepolymerization, the prepolymerization product is obtained. This prepolymerization product is then transferred to the final polymerization reactor, where the temperature is 200℃ and the pressure is 200 Pa. After 8 hours of reaction, the copolymer melt is obtained. This melt is then processed through a water-cooled granulation device to obtain the copolymer product, which is injection-grade chips.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that the single-chain separation reaction step was not performed. The specific steps are as follows:

[0068] Terephthalic acid (PTA) and 1,4-butanediol (BDO) were mixed in a first mixing tank at a molar ratio of 1:1.8 and fed into a first esterification reactor at a rate of 560 kg / h. Zinc acetate catalyst was added to the first esterification reactor at a rate of 1.5 kg / h. The temperature of the first esterification reactor was controlled at 200°C and the pressure at 20 kPa. The reaction was held for 6 hours, and the water in the reaction product was removed to obtain the esterified product. BDO and dimethyl carbonate (DMC) were weighed at a molar ratio of 1:2.5. BDO was added to a second mixing tank and mixed, then fed into a second esterification reactor at a rate of 340 kg / h. DMC was added to the second esterification reactor in portions, and magnesium acetate catalyst was added to the second esterification reactor at a rate of 1 kg / h. The reaction temperature of the second esterification reactor was controlled at 160°C and the reaction pressure at atmospheric pressure. The reaction was held for 20 hours, during which the content of the azeotropic species BDO in the second esterification reactor was maintained at 20%–80%. The reaction yielded the transesterification product. The esterification product and transesterification product were continuously fed into the prepolymerization reactor via pipelines at rates of 560 kg / h and 340 kg / h, respectively. Ethylene glycol antimony catalyst and triphenyl phosphite stabilizer were injected into the pipelines at a rate of 0.2 kg / h. The esterification product, transesterification product, ethylene glycol antimony catalyst, and triphenyl phosphite stabilizer were then fed into the prepolymerization reactor via a high-shear homogenization pump. The temperature in the prepolymerization reactor was set at 180°C and the pressure at 90 kPa. After 3 hours of prepolymerization, the prepolymerization product was obtained. This prepolymerization product was then transferred to the final polymerization reactor, where the temperature was set at 200°C and the pressure at 200 Pa. After 10 hours of reaction, the copolymer melt was obtained. This melt was then processed through a water-cooled granulation device to obtain the copolymer product, which was injection-molded chips.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 3 is that the esterification product, the demonochemical product, the antimony glycolate catalyst, and the triphenyl phosphite stabilizer were not passed through a high-shear homogenization pump and were directly introduced into the prepolymerization reactor for reaction. The specific steps are as follows:

[0071] Terephthalic acid (PTA) and 1,4-butanediol (BDO) were mixed in a first mixing tank at a molar ratio of 1:2.5 and fed into a first esterification reactor at a rate of 560 kg / h. Zinc acetate catalyst was added to the first esterification reactor at a rate of 1.5 kg / h. The temperature of the first esterification reactor was controlled at 190°C and the pressure at 23 kPa. The reaction was held for 6 hours, and the water in the reaction product was removed to obtain the esterified product.

[0072] BDO and dimethyl carbonate (DMC) were weighed at a molar ratio of 1:1.7. BDO was added to the second mixing tank and then fed into the second esterification reactor at a rate of 340 kg / h. DMC was added to the second esterification reactor in portions, and magnesium acetate catalyst was added at a rate of 1 kg / h. The reaction temperature in the second esterification reactor was controlled at 160°C, the reaction pressure at atmospheric pressure, and the reaction was held for 20 h. During this period, the azeotropic BDO content in the second esterification reactor was maintained between 20% and 80%. The resulting transesterification product was continuously transferred to a demonotropic reactor, where the reaction temperature was controlled at 150°C, the pressure at 50 kPa, and the reaction time at 3 h to obtain the demonotropic product.

[0073] The esterification product and the demonopolymerization product were continuously fed into the prepolymerization reactor via a pipeline at rates of 560 kg / h and 340 kg / h, respectively. Ethylene glycol antimony catalyst and triphenyl phosphite stabilizer were injected into the pipeline at a rate of 0.2 kg / h. The temperature in the prepolymerization reactor was set at 180℃ and the pressure at 90 kPa. After 3 hours of polymerization, the prepolymerization product was obtained. This prepolymerization product was then transferred to the final polymerization reactor at 190℃ and the pressure at 90 kPa. After 5 hours of reaction, the copolymer melt was obtained. The copolymer melt was then transferred to a dynamic mixing reactor, where a chain extender was added. The dynamic mixing reactor was set at 100 kPa and the temperature at 190℃ for 3 hours of continuous reaction, yielding the copolymer melt. After passing through a water-cooled granulation device, the copolymer product was obtained as blow-molded chips.

[0074] Comparative Example 4

[0075] The difference between this comparative example and Example 3 is that, in step S2, the content of diester in the azeotrope of the second esterification vessel was not controlled to be between 20% and 80%. The specific steps are as follows:

[0076] Terephthalic acid (PTA) and 1,4-butanediol (BDO) were mixed in a first mixing tank at a molar ratio of 1:1.8 and fed into a first esterification reactor at a rate of 560 kg / h. Zinc acetate catalyst was added to the first esterification reactor at a rate of 1.5 kg / h. The temperature of the first esterification reactor was controlled at 190°C and the pressure at 23 kPa. The reaction was held for 6 hours, and the water in the reaction product was removed to obtain the esterified product.

[0077] BDO and dimethyl carbonate (DMC) were weighed at a molar ratio of 1:2.5. The BDO was added to the second mixing tank and then fed into the second esterification reactor at a rate of 340 kg / h. All the DMC was added to the second esterification reactor at once, and magnesium acetate catalyst was added at a rate of 1 kg / h. The reaction temperature in the second esterification reactor was controlled at 160°C, the reaction pressure at atmospheric pressure, and the reaction was held for 20 h. The resulting transesterification product was continuously transferred to a demonotransfer reactor, where the reaction temperature was controlled at 150°C, the pressure at 50 kPa, and the reaction time at 3 h to obtain the demonotransfer product.

[0078] The esterification product and the demonopolymerization product were continuously fed into the prepolymerization reactor via pipelines at rates of 560 kg / h and 340 kg / h, respectively. Ethylene glycol antimony catalyst and triphenyl phosphite stabilizer were injected into the pipelines at a rate of 0.2 kg / h. The esterification product, demonopolymerization product, ethylene glycol antimony catalyst, and triphenyl phosphite stabilizer were then fed into the prepolymerization reactor via a high-shear homogenizing pump. The temperature in the prepolymerization reactor was set at 180°C and the pressure at 90 kPa. After 3 hours of polycondensation, the prepolymerization product was obtained. This prepolymerization product was then transferred to the final polycondensation reactor, where the temperature was set at 190°C and the pressure at 90 kPa. After 5 hours of reaction, the copolymer melt was obtained. The copolymer melt was then transferred to a dynamic mixing reactor, where a chain extender was added. The dynamic mixing reactor was set at a pressure of 100 kPa and a temperature of 190°C, and the reaction was continued for 3 hours to obtain the copolymer melt. After passing through a water-cooled granulation device, the copolymer product was obtained as blow-molded chips.

[0079] The copolyester chips prepared in the examples and comparative examples were subjected to basic performance tests and barrier performance tests, and the results are shown in Tables 1-2 below. The biodegradability rate was tested under industrial composting conditions for a 4-month degradation period. Other properties were tested according to industry standards. Barrier performance was tested according to the national standard GB / T 1038.1-2022.

[0080] Table 1. Basic Performance Test Table of Copolyester Products in Examples and Comparative Cases

[0081]

[0082] Analysis of experimental results:

[0083] The copolyesters prepared in the embodiments of this invention have a weight-average molecular weight of over 88,800 g / mol, with a maximum reaching 124,900 g / mol, far exceeding the copolyesters prepared in the comparative examples and existing technologies. Furthermore, the copolyesters prepared in these embodiments exhibit higher tensile strength and melting point than those prepared in the comparative examples, demonstrating superior performance and enabling wider application in high-end packaging.

[0084] Compared to Example 1, Comparative Example 1 changed the raw material ratio. Compared to Example 1, its weight-average molecular weight and tensile strength decreased significantly. This is because after the ratio of carbonate diester to aliphatic diol was changed, the side reactions increased and the molecular configuration of the transesterification products changed, resulting in a decrease in the weight-average molecular weight of the final synthesized copolyester product.

[0085] Comparative Example 2 did not undergo a de-monomerization reaction, thus failing to remove the small molecule polymers and oligomers generated during esterification. This reduced the molecular configuration and distribution of the copolyester that would affect subsequent polycondensation reactions, which was detrimental to the synthesis of high molecular weight copolyesters.

[0086] Comparative Example 3 did not undergo high-speed shear homogenization before polycondensation. In this invention, high-speed shear homogenization can increase the residence time of catalyst, stabilizer, esterification product and demonochemical product in the pipeline. High-speed shear homogenization ensures that all raw materials are mixed evenly before entering the pre-polycondensation reaction.

[0087] Comparative Example 4 did not control the proportion of diester in the distillate because all diester was added at once during the initial feedstock addition, hindering the forward transesterification reaction. The inventors of this application discovered during experiments that adding diester in batches significantly promotes the forward reaction, reducing side reactions and the amount of diester required. This also leads to a substantial improvement in the performance of the final copolyester. Optimal is adding it in three stages, ensuring the optimal proportion of diester in the distillate and facilitating the most rapid reaction.

[0088] Table 2. Barrier performance test results of copolyester products prepared in the Examples and Comparative Examples.

[0089]

[0090] The experimental results above show that the copolyester material prepared by this invention has better gas barrier properties than the copolyester material prepared in the comparative example. This is because the copolyester prepared by this invention has a higher weight-average molecular weight and a more compact internal molecular structure, effectively blocking various gas molecules and significantly broadening the application scenarios of the copolyester prepared by this invention.

[0091] While several embodiments of the present invention have been provided herein, those skilled in the art should understand that modifications can be made to these embodiments without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the invention.

Claims

1. A method for producing polyaromatic-carbonic-aliphatic copolyester, characterized in that, Includes the following steps: S1. Aromatic dicarboxylic acid and aliphatic diol are mixed to form a homogeneous slurry, which is then fed into the first esterification reactor and an esterification catalyst is added to carry out the esterification reaction to obtain the esterification product. The molar ratio of aromatic dicarboxylic acid to aliphatic diol in the homogeneous slurry is 1:1.5 to 1:

3. S2. After the aliphatic diols are mixed evenly, they are fed into the second esterification reactor. Then, diester carbonate and esterification catalyst are added to the second esterification reactor to carry out the esterification reaction and obtain the esterification product. The esterification product is sent to the monomer removal reactor to remove small molecules and oligomers to obtain the monomer removal product. The molar ratio of diester carbonate to aliphatic diol is 1.5:1 to 3:

1. The content of diester carbonate in the azeotrope of the second esterification reactor is 20% to 80%. The diester carbonate is added in batches. S3. The esterification product obtained in S1 and the demonopolymerization product obtained in S2 are mixed with polycondensation catalyst and stabilizer. After shearing and homogenization, the mixture is fed into a pre-polycondensation reactor to react and obtain a pre-polycondensation product. The pre-polycondensation product is then fed into a final polycondensation reactor to react and obtain a copolymer. The copolymer is then fed into a thickening reactor and / or a dynamic mixing reactor to react and then water-cooled and granulated to obtain a copolyester product.

2. The method for producing polyaromatic-carbonic-aliphatic copolyester as described in claim 1, characterized in that, The aliphatic diols in steps S1 and S2 include one or more of the following: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2,4-trimethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-tert-butyl-1,3-propanediol, and 2,2,4-trimethyl-1,6-hexanediol. The carbonate diester includes one or more of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, diphenyl carbonate, xylene carbonate, and dinaphthalene carbonate; The aromatic dicarboxylic acid includes one or both of terephthalic acid and naphthalenecyclodicarboxylic acid.

3. The method for producing a polyaromatic-carbonic-aliphatic copolyester as described in claim 1, characterized in that, The esterification catalyst and transesterification catalyst include one or more of acetate, titanium compounds, antimony compounds, germanium compounds and rare earth compounds; The polycondensation catalyst includes one or more of titanium-based compounds, antimony-based compounds, germanium-based compounds, tin-based compounds, and rare earth compounds; The stabilizer includes one or a mixture of several of the following: trimethyl phosphate, triethyl phosphate, tripropyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, tripropyl phosphite, triphenyl phosphite, phosphorous acid, or phosphoric acid.

4. The method for producing a polyaromatic-carbonic-aliphatic copolyester as described in claim 1, characterized in that, In step S1, the amount of esterification catalyst used is 0.001 to 5 wt% of the sum of the masses of the aromatic dicarboxylic acid and the aliphatic diol; the reaction temperature of the first esterification reactor is 160 to 250°C, the pressure is 10 to 30 kPa, and the reaction time is 4 to 10 h.

5. The method for producing a polyaromatic-carbonate-aliphatic copolyester as described in claim 1, characterized in that, In step S2, the amount of transesterification catalyst used is 0.001–5 wt% of the sum of the mass of the diester and the aliphatic diol; the reaction temperature of the second esterification reactor is 90–200 °C, and the reaction time is 10–30 h; the reaction temperature of the demonolysis reactor is 120–200 °C, the pressure is 10–70 kPa, and the reaction time is 1–6 h.

6. The method for producing a polyaromatic-carbonate-aliphatic copolyester as described in claim 1, characterized in that, In step S3, the amount of polycondensation catalyst used is 0.005–5 wt% of the sum of the weights of the monopolymerization product and the esterification product, and the amount of stabilizer used is 0.001–1 wt% of the sum of the weights of the monopolymerization product and the esterification product; the reaction temperature in the prepolymerization reactor is 160–230°C, the pressure is 70–90 kPa, and the reaction time is 2–8 h; the reaction temperature in the final polymerization reactor is 180–230°C, the pressure is 90–99 kPa, and the reaction time is 4–8 h.

7. The method for producing polyaromatic-carbonic-aliphatic copolyester as described in claim 1, characterized in that, In step S3, the reaction temperature in the thickening reactor is 180–230℃, the pressure is 5–1000 Pa, and the reaction time is 0–8 h; the reaction in the dynamic mixing reactor is 160–240℃, the pressure is 90–100 kPa, and the residence time is 0–60 min.

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