CN112745489A - Continuous preparation method of biodegradable block copolyester and biodegradable block copolyester - Google Patents
Continuous preparation method of biodegradable block copolyester and biodegradable block copolyester Download PDFInfo
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- CN112745489A CN112745489A CN202110067901.2A CN202110067901A CN112745489A CN 112745489 A CN112745489 A CN 112745489A CN 202110067901 A CN202110067901 A CN 202110067901A CN 112745489 A CN112745489 A CN 112745489A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/16—Dicarboxylic acids and dihydroxy compounds
- C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
- C08G63/181—Acids containing aromatic rings
- C08G63/183—Terephthalic acids
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/16—Dicarboxylic acids and dihydroxy compounds
- C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
- C08G63/199—Acids or hydroxy compounds containing cycloaliphatic rings
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/78—Preparation processes
- C08G63/82—Preparation processes characterised by the catalyst used
- C08G63/84—Boron, aluminium, gallium, indium, thallium, rare-earth metals, or compounds thereof
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Abstract
本发明公开了一种生物可降解嵌段共聚酯连续制备方法及生物可降解嵌段共聚酯，制备方法包括：将对苯二甲酸、脂肪族二元酸和乙二醇制备成浆料，进行酯化、缩聚，得到聚酯预聚物熔体，将聚丁二酸丁二醇酯与酯交换催化剂熔融，得到聚丁二酸丁二醇酯混合熔体；将所述聚酯预聚物熔体和聚丁二酸丁二醇酯混合熔体汇流后，输送至终缩聚反应系统，进行终缩聚反应，得到生物可降解嵌段共聚酯熔体；所述生物可降解嵌段共聚酯熔体经成型，结晶，切粒，得到生物可降解嵌段共聚酯结晶切片。本发明的制备方法可连续进行，制备过程中不会产生四氢呋喃，提高了乙二醇的回收利用率，制备得到的共聚酯热学性能和物理加工性能好。The invention discloses a continuous preparation method of a biodegradable block copolyester and a biodegradable block copolyester. The preparation method comprises: preparing a slurry from terephthalic acid, aliphatic dibasic acid and ethylene glycol , carry out esterification and polycondensation to obtain polyester prepolymer melt, melt polybutylene succinate and transesterification catalyst to obtain polybutylene succinate mixed melt; After the polymer melt and the polybutylene succinate mixed melt converge, they are transported to the final polycondensation reaction system for final polycondensation reaction to obtain a biodegradable block copolyester melt; the biodegradable block The copolyester melt is formed, crystallized and pelletized to obtain biodegradable block copolyester crystal chips. The preparation method of the invention can be carried out continuously, no tetrahydrofuran is generated in the preparation process, the recovery rate of ethylene glycol is improved, and the prepared copolyester has good thermal properties and physical processing properties.
Description
Technical Field
The invention belongs to the field of high polymer materials, and particularly relates to a continuous preparation method of biodegradable block copolyester and biodegradable block copolyester.
Background
With the increasing severity of the environmental pollution problem, biodegradable polymers are attracting more and more attention. At present, most of biodegradable materials are aliphatic polyesters. Aliphatic polyesters have poor thermal and physical processability properties, which have greatly limited applications in industrial and agricultural fields.
In recent years, in order to obtain low-cost biodegradable polymers having both satisfactory thermal and physical processability and biodegradability, some researchers have focused on the synthesis of copolyesters via aliphatic and aromatic units.
Among them, polyethylene terephthalate (PET) is a very important thermoplastic, and has wide applications in industrial and technical fields. The poly (butylene succinate) (PBS) is a biodegradable polymer which is easy to obtain, and researches find that the copolymer with the chain structures of the two polymers has good performances of the two polymers.
In the production process of polyethylene terephthalate (PET), PBEST copolyester is synthesized by adopting a one-step method. Specifically, Succinic Acid (SA), 1, 4-Butanediol (BDO), Ethylene Glycol (EG) and terephthalic acid (TPA) are directly pulped and polymerized and condensed to prepare the PBEST copolyester. In the preparation process, 1, 4-Butanediol (BDO) is easy to generate tetrahydrofuran, and the properties of the copolyester are influenced, and meanwhile, the production equipment is damaged. 1, 4-Butanediol (BDO) fraction in the polycondensation reaction process is easy to pollute ethylene glycol fraction, so that the ethylene glycol is difficult to directly recycle.
Synthesis, characterization, and Properties of poly (ethylene terephthalate)/poly (1,4-butylene succinate) block copolymers (P1321. sup. 1330) in Polymer journal No. 44, vol.5, published 3.2003 describes the preparation of poly [ (butylene succinate) -co- (ethylene terephthalate) ] (PET-PBS) block copolyesters by treatment with polyethylene terephthalate (PET) and poly (1,4-butylene succinate) (PBS) at 290 ℃. The block copolyester prepared by the method needs to be prepared respectively from polyethylene glycol terephthalate and poly (1,4-butylene succinate) polymer or oligomer, has complex process, is difficult to realize continuous preparation on a conventional polyethylene terephthalate (PET) production line, and simultaneously has viscosity which is rapidly reduced along with the increase of processing time, thereby bringing great difficulty to the synthesis of the copolyester.
"A new biodegradable copolyester poly (butylene succinate-co-ethylene succinate-co-ethylene terephthalate)" published on 12/1 of 2004 in the journal of Acta Materialia volume 52, volume 20 describes a process of preparing poly [ (butylene succinate) -co- (ethylene terephthalate) ] (PBEST) by mixing three prepolymers, first, with Succinic Acid (SA), 1, 4-Butanediol (BDO), Ethylene Glycol (EG), and terephthalic acid (TPA). The copolyester is prepared by a two-step method, the process is complex, and the copolyester is difficult to prepare continuously.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to solve the technical problems that the existing degradable polymer is poor in thermal property and physical processing property, tetrahydrofuran is easily generated in the preparation process, the recycling rate of ethylene glycol is poor, and continuous production is difficult to realize.
In order to solve the technical problems, the invention adopts the technical scheme that:
a method for continuously preparing biodegradable block copolyester,
(1) preparing terephthalic acid, aliphatic dibasic acid and ethylene glycol into slurry, and carrying out esterification and polycondensation to obtain a polyester prepolymer melt;
(2) melting polybutylene succinate and an ester exchange catalyst to obtain a polybutylene succinate mixed melt;
(3) converging the polyester prepolymer melt and the polybutylene succinate mixed melt, and conveying the converged melt to a final polycondensation reaction system for final polycondensation reaction to obtain a biodegradable block copolyester melt;
(4) and forming, crystallizing and granulating the biodegradable block copolyester melt to obtain the biodegradable block copolyester crystal slice.
The invention controls the sequence length in the aromatic chain segment in the polyester prepolymer not to exceed 2 by adding the fatty acid dibasic acid, and ensures the biodegradability of the block copolyester. By adding the polybutylene succinate mixed melt before the final polycondensation reaction, 1, 4-butanediol and succinic acid are prevented from being added in the slurry preparation stage, and tetrahydrofuran generated in the esterification reaction of the 1, 4-butanediol and succinic acid is further prevented. Meanwhile, the invention can also avoid the 1, 4-butanediol and the glycol from being distilled out together to pollute glycol fraction in the polycondensation stage. Therefore, the invention can realize the direct recovery of the ethylene glycol fraction without rectification and purification.
Further, the molar ratio of terephthalic acid, aliphatic dibasic acid and ethylene glycol in the step (1) is
1:0.1-0.5:1.5-2.0, and the melt intrinsic viscosity of the polyester prepolymer is 0.1-0.50 dL/g.
Further, the aliphatic dibasic acid is selected from one of succinic acid, adipic acid, oxalic acid, cyclohexanedicarboxylic acid and sebacic acid.
Further, in the step (1), the terephthalic acid, the aliphatic dibasic acid and the ethylene glycol are esterified in an esterification kettle, wherein the esterification temperature is between 200 ℃ and 250 ℃.
Further, the temperature of the polycondensation in the step (1) is between 240 ℃ and 270 ℃.
Further, the ester exchange catalyst in the step (2) is an organic rare earth catalyst;
preferably, the transesterification catalyst is selected from at least one of an organolanthanum catalyst, an organocerium catalyst, an organopraseodymium catalyst, an organoneodymium catalyst, and an organoscandium catalyst.
Further, in the step (2), the transesterification catalyst is selectedFrom rare earth alkoxides X (OR)2) n, rare earth carboxylate X (R)1COO) n, rare earth aryloxide X (OAr) n;
preferably, said R is1Is ethyl or propyl, R2Is isopropyl, n-butyl or isoamyl;
preferably, X is a rare earth element.
Furthermore, in the step (2), the intrinsic viscosity of the poly (butylene succinate) is 0.5-3.5 dL/g.
The poly (butylene succinate) has too low intrinsic viscosity, low molecular weight and too short chain segment, is not beneficial to ester exchange, can remove more 1, 4-butanediol and generate tetrahydrofuran to influence the performance of final polycondensation copolyester; the intrinsic viscosity of the polybutylene succinate melt is too high, and the melt is difficult to convey and mix. Therefore, the intrinsic viscosity of the poly (butylene succinate) in the method is 0.5-3.5 dL/g.
Further, in the step (3), the flow rate of the polybutylene succinate mixed melt is 10-50% of the flow rate of the polyester prepolymer melt;
preferably, the polybutylene succinate mixed melt is metered by a melt metering gear pump.
The injection amount of the polybutylene succinate mixed melt is accurately measured by the melt measuring gear pump, so that the content of the polybutylene succinate chain segment in the biodegradable block copolyester molecular chain is controlled.
Further, in the step (4), after converging the mixed melt of the polyester prepolymer melt and the polybutylene succinate, filtering the mixed melt by using a melt filter, injecting the mixed melt into a final polycondensation reaction system, wherein the filtering precision of the melt filter is 10-30 mu m, and the reaction temperature of the final polycondensation reaction system is 250-280 ℃.
The invention realizes the static mixing of the polyester prepolymer melt and the polybutylene succinate mixed melt by using the melt filter.
And further filtering the biodegradable block copolyester melt through a melt filter, conveying the filtered biodegradable block copolyester melt to a casting belt head, molding the casting belt, cooling the casting belt by blowing, slowly releasing, crystallizing and granulating to obtain the biodegradable block copolyester crystal slice.
Preferably, the blowing temperature of the cast strip blowing cooling is 10-50 ℃.
The invention also provides a biodegradable block copolyester which is prepared by any one of the preparation methods, wherein the sequence length of the aromatic polyester chain segment of the biodegradable block copolyester is not more than 2, the intrinsic viscosity is 0.6-1.5dL/g, and the crystallinity is not less than 5%.
In the method, the content of 1, 4-butanediol in the ethylene glycol fraction collected in the polycondensation stage is not higher than 0.5%, and the content of tetrahydrofuran as a byproduct is not higher than 0.1%.
After adopting the technical scheme, compared with the prior art, the invention has the following beneficial effects: according to the invention, a succinic acid and 1, 4-butanediol structural unit is introduced into a copolyester polymerization reaction system in a manner of adding a polybutylene succinate mixed melt on line before a final polycondensation reaction. The mode avoids the generation of tetrahydrofuran by-products by high-temperature dehydration and cyclization of the 1, 4-butanediol and avoids the high-temperature evaporation of the free 1, 4-butanediol into the condensed polyethylene glycol fraction, so that the content of the 1, 4-butanediol in the ethylene glycol fraction collected in the condensation polymerization stage is not higher than 0.5 percent and the content of the tetrahydrofuran by-products is not higher than 0.1 percent.
Impurities of 1, 4-butanediol and tetrahydrofuran in the ethylene glycol fraction are not higher than 0.1 percent, so that the requirement of direct reutilization of ethylene glycol as a raw material can be met, and the ethylene glycol fraction does not need to be rectified and purified.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments are clearly and completely described below, and the following embodiments are used for illustrating the present invention and are not used for limiting the scope of the present invention.
Example 1:
(1) preparing terephthalic acid, succinic acid and ethylene glycol into slurry, wherein the molar ratio of the terephthalic acid to the succinic acid to the ethylene glycol in the slurry is as follows: 1: 0.2: 1.5.
(2) and (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, and carrying out esterification at the temperature of 220 ℃ to form a polyester prepolymer.
(3) Injecting the polyester prepolymer into a pre-polycondensation system, finishing polycondensation at the temperature of 250 ℃ to obtain a polyester prepolymer melt with the intrinsic viscosity of 0.3dL/g, metering by a melt metering gear pump, and conveying from the pre-polycondensation system to a prepolymer melt pipeline.
(4) Melting polybutylene succinate with the intrinsic viscosity of 1.0dL/g and a lanthanum acetate ester exchange catalyst by a screw extruder to form a polybutylene succinate mixed melt, metering the polybutylene succinate mixed melt by a melt metering gear pump, and injecting the polybutylene succinate mixed melt into a prepolymer melt pipeline, wherein the injection flow is 20% of the polyester prepolymer melt flow.
(5) Converging the mixed melt of the polyester prepolymer melt and the polybutylene succinate, filtering the mixed melt by a prepolymer melt filter, conveying the mixed melt to a final polycondensation reaction system, and performing final polycondensation reaction at 260 ℃ with the precision of the prepolymer melt filter being 10 mu m to obtain the biodegradable block copolyester melt.
(6) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying the filtered biodegradable block copolyester melt to a casting belt head, molding the casting belt, cooling the casting belt by cooling wind at 50 ℃, and granulating after slow-release crystallization to obtain the biodegradable block copolyester crystal slice with the intrinsic viscosity of 1.0 dL/g.
Example 2:
(1) preparing terephthalic acid, oxalic acid and ethylene glycol into slurry, wherein the molar ratio of the terephthalic acid to the oxalic acid to the ethylene glycol in the slurry is as follows: 1: 0.42: 2.0.
(2) and (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, and carrying out esterification at the temperature of 200 ℃ to form a polyester prepolymer.
(3) The polyester prepolymer is injected into a pre-polycondensation system, polycondensation is completed at the temperature of 240 ℃, a polyester prepolymer melt with the intrinsic viscosity of 0.1dL/g is obtained, and the polyester prepolymer melt is conveyed to a prepolymer melt pipeline from the pre-polycondensation system after being metered by a melt metering gear pump.
(4) Melting polybutylene succinate with the intrinsic viscosity of 0.5dL/g and a cerium propionate transesterification catalyst by a screw extruder to form a polybutylene succinate mixed melt, metering the polybutylene succinate mixed melt by a melt metering gear pump, and injecting the polybutylene succinate mixed melt into a prepolymer melt pipeline, wherein the injection flow is 50% of the polyester prepolymer melt flow.
(5) Converging the mixed melt of the polyester prepolymer melt and the polybutylene succinate, filtering the mixed melt by a prepolymer melt filter, conveying the mixed melt to a final polycondensation reaction system, and performing final polycondensation reaction at 250 ℃, wherein the precision of the prepolymer melt filter is 20 mu m, so as to obtain the biodegradable block copolyester melt.
(6) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying the filtered biodegradable block copolyester melt to a casting belt head, molding the casting belt, cooling the casting belt by cooling wind at 50 ℃, and granulating after slow-release crystallization to obtain the biodegradable block copolyester crystal slice with the intrinsic viscosity of 0.6 dL/g.
Example 3:
(1) preparing terephthalic acid, sebacic acid and ethylene glycol into slurry, wherein the molar ratio of the terephthalic acid to the sebacic acid to the ethylene glycol in the slurry is as follows: 1: 0.3: 1.6.
(2) and (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, and carrying out esterification at the temperature of 230 ℃ to form a polyester prepolymer.
(3) Injecting the polyester prepolymer into a pre-polycondensation system, finishing polycondensation at the temperature of 260 ℃ to obtain a polyester prepolymer melt with the intrinsic viscosity of 0.4dL/g, metering by a melt metering gear pump, and conveying from the pre-polycondensation system to a prepolymer melt pipeline.
(4) Melting polybutylene succinate with the intrinsic viscosity of 1.5dL/g and a lanthanum acetate ester exchange catalyst by a screw extruder to form a polybutylene succinate mixed melt, metering the polybutylene succinate mixed melt by a melt metering gear pump, and injecting the polybutylene succinate mixed melt into a prepolymer melt pipeline, wherein the injection flow is 10% of the polyester prepolymer melt flow.
(5) Converging the mixed melt of the polyester prepolymer melt and the polybutylene succinate, filtering the mixed melt by a prepolymer melt filter, conveying the mixed melt to a final polycondensation reaction system, and performing final polycondensation reaction at 270 ℃, wherein the precision of the prepolymer melt filter is 30 mu m, so as to obtain the biodegradable block copolyester melt.
(6) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying the filtered biodegradable block copolyester melt to a casting belt head, molding the casting belt, cooling the casting belt by cooling air blowing at 10 ℃, and granulating after slow-release crystallization to obtain the biodegradable block copolyester crystal slice with the intrinsic viscosity of 0.8 dL/g.
Example 4:
(1) preparing terephthalic acid, cyclohexanedicarboxylic acid and ethylene glycol into slurry, wherein the molar ratio of the terephthalic acid to the cyclohexanedicarboxylic acid to the ethylene glycol in the slurry is as follows: 1: 0.1: 1.5.
(2) and (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, and carrying out esterification at the temperature of 250 ℃ to form a polyester prepolymer.
(3) The polyester prepolymer is injected into a pre-polycondensation system, polycondensation is completed at the temperature of 270 ℃, a polyester prepolymer melt with the intrinsic viscosity of 0.5dL/g is obtained, and the polyester prepolymer melt is conveyed to a prepolymer melt pipeline from the pre-polycondensation system after being metered by a melt metering gear pump.
(4) After the polybutylene succinate with the intrinsic viscosity of 3.5dL/g and the isopentyl scandium transesterification catalyst are melted by a screw extruder, a polybutylene succinate mixed melt is formed, the polybutylene succinate mixed melt is metered by a melt metering gear pump and then is injected into a prepolymer melt pipeline, and the injection flow is 30% of the polyester prepolymer melt flow.
(5) Converging the mixed melt of the polyester prepolymer melt and the polybutylene succinate, filtering the mixed melt by a prepolymer melt filter, conveying the mixed melt to a final polycondensation reaction system, and performing final polycondensation reaction at 280 ℃, wherein the precision of the prepolymer melt filter is 20 mu m, so as to obtain the biodegradable block copolyester melt.
(6) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying the filtered biodegradable block copolyester melt to a casting belt head, molding the casting belt, cooling the casting belt by cooling air blowing at 10 ℃, and granulating after slow-release crystallization to obtain the biodegradable block copolyester crystal slice with the intrinsic viscosity of 1.5 dL/g.
Example 5:
(1) preparing terephthalic acid, adipic acid and ethylene glycol into slurry, wherein the molar ratio of the terephthalic acid to the adipic acid to the ethylene glycol in the slurry is as follows: 1: 0.5: 1.8.
(2) and (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, and carrying out esterification at the temperature of 230 ℃ to form a polyester prepolymer.
(3) Injecting the polyester prepolymer into a pre-polycondensation system, finishing polycondensation at the temperature of 250 ℃ to obtain a polyester prepolymer melt with the intrinsic viscosity of 0.3dL/g, metering by a melt metering gear pump, and conveying from the pre-polycondensation system to a prepolymer melt pipeline.
(4) Melting polybutylene succinate with the intrinsic viscosity of 2.8dL/g and a neodymium n-butoxide ester exchange catalyst by a screw extruder to form a polybutylene succinate mixed melt, metering the polybutylene succinate mixed melt by a melt metering gear pump, and injecting the polybutylene succinate mixed melt into a prepolymer melt pipeline, wherein the injection flow is 10% of the polyester prepolymer melt flow.
(5) Converging the mixed melt of the polyester prepolymer melt and the polybutylene succinate, filtering the mixed melt by a prepolymer melt filter, conveying the mixed melt to a final polycondensation reaction system, and performing final polycondensation reaction at 270 ℃, wherein the precision of the prepolymer melt filter is 20 mu m, so as to obtain the biodegradable block copolyester melt.
(6) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying the filtered biodegradable block copolyester melt to a casting belt head, molding the casting belt, cooling the casting belt by cooling air blowing at 40 ℃, and granulating after slow-release crystallization to obtain the biodegradable block copolyester crystal slice with the intrinsic viscosity of 1.1 dL/g.
Example 6:
(1) preparing terephthalic acid, cyclohexanedicarboxylic acid and ethylene glycol into slurry, wherein the molar ratio of the terephthalic acid to the cyclohexanedicarboxylic acid to the ethylene glycol in the slurry is as follows: 1: 0.2: 1.5.
(2) and (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, and carrying out esterification at the temperature of 240 ℃ to form a polyester prepolymer.
(3) Injecting the polyester prepolymer into a pre-polycondensation system, finishing polycondensation at the temperature of 260 ℃ to obtain a polyester prepolymer melt with the intrinsic viscosity of 0.3dL/g, metering by a melt metering gear pump, and conveying from the pre-polycondensation system to a prepolymer melt pipeline.
(4) Melting polybutylene succinate with the intrinsic viscosity of 0.8dL/g and a phenoxy neodymium ester exchange catalyst by a screw extruder to form a polybutylene succinate mixed melt, metering the polybutylene succinate mixed melt by a melt metering gear pump, and injecting the polybutylene succinate mixed melt into a prepolymer melt pipeline, wherein the injection flow is 20% of the polyester prepolymer melt flow.
(5) Converging the mixed melt of the polyester prepolymer melt and the polybutylene succinate, filtering the mixed melt by a prepolymer melt filter, conveying the mixed melt to a final polycondensation reaction system, and performing final polycondensation reaction at 280 ℃, wherein the precision of the prepolymer melt filter is 10 mu m, so as to obtain the biodegradable block copolyester melt.
(6) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying the filtered biodegradable block copolyester melt to a casting belt head, molding the casting belt, cooling the casting belt by cooling air blowing at 40 ℃, and granulating after slow-release crystallization to obtain the biodegradable block copolyester crystal slice with the intrinsic viscosity of 1.3 dL/g.
Example 7:
(1) preparing terephthalic acid, sebacic acid and ethylene glycol into slurry, wherein the molar ratio of the terephthalic acid to the sebacic acid to the ethylene glycol in the slurry is as follows: 1: 0.2: 1.6.
(2) and (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, and carrying out esterification at the temperature of 220 ℃ to form a polyester prepolymer.
(3) Injecting the polyester prepolymer into a pre-polycondensation system, finishing polycondensation at the temperature of 260 ℃ to obtain a polyester prepolymer melt with the intrinsic viscosity of 0.4dL/g, metering by a melt metering gear pump, and conveying from the pre-polycondensation system to a prepolymer melt pipeline.
(4) After the poly (butylene succinate) with the intrinsic viscosity of 1.5dL/g and the isopropoxy praseodymium transesterification catalyst are melted by a screw extruder, a poly (butylene succinate) mixed melt is formed, and the poly (butylene succinate) mixed melt is metered by a melt metering gear pump and then injected into a prepolymer melt pipeline, wherein the injection flow is 10% of the polyester prepolymer melt flow.
(5) Converging the mixed melt of the polyester prepolymer melt and the polybutylene succinate, filtering the mixed melt by a prepolymer melt filter, conveying the mixed melt to a final polycondensation reaction system, and performing final polycondensation reaction at 270 ℃, wherein the precision of the prepolymer melt filter is 20 mu m, so as to obtain the biodegradable block copolyester melt.
(6) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying the filtered biodegradable block copolyester melt to a casting belt head, molding the casting belt, cooling the casting belt by cooling air blowing at 10 ℃, and granulating after slow-release crystallization to obtain the biodegradable block copolyester crystal slice with the intrinsic viscosity of 0.9 dL/g.
Comparative example 1:
(1) preparing terephthalic acid, succinic acid and ethylene glycol into slurry, wherein the molar ratio of the terephthalic acid to the succinic acid to the ethylene glycol in the slurry is as follows: 1: 0.2: 1.5.
(2) and (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, carrying out esterification at the temperature of 220 ℃ to form a polyester prepolymer melt, metering by a melt metering gear pump, and conveying to an oligomer melt pipeline from an esterification system.
(3) Melting polybutylene succinate with the intrinsic viscosity of 1.0dL/g and a lanthanum acetate ester exchange catalyst by a screw extruder to form a polybutylene succinate mixed melt, metering the polybutylene succinate mixed melt by a melt metering gear pump, and injecting the polybutylene succinate mixed melt into a prepolymer melt pipeline, wherein the injection flow is 20% of the polyester prepolymer melt flow.
(4) Converging the mixed melt of the polyester prepolymer and the polybutylene succinate, filtering the mixed melt by a prepolymer melt filter, conveying the mixed melt to a pre-polycondensation reaction system, and carrying out pre-polycondensation reaction at 240 ℃ to obtain the polyester prepolymer melt with the intrinsic viscosity of 0.3 dL/g.
(5) And conveying the polyester prepolymer melt to a final polycondensation reaction system for final polycondensation reaction at 260 ℃ to obtain the biodegradable block copolyester melt.
(6) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying to a casting belt head, molding the casting belt, cooling the casting belt by cooling water, and granulating to obtain the biodegradable block copolyester slice with the intrinsic viscosity of 1.0 dL/g.
Comparative example 2:
(1) preparing terephthalic acid, succinic acid, ethylene glycol and 1, 4-butanediol into slurry, wherein the molar ratio of the terephthalic acid to the succinic acid to the ethylene glycol to the 1, 4-butanediol in the slurry is as follows: 1:0.46:1.5:0.26, 46 mol parts of succinic acid, 150 mol parts of ethylene glycol and 26 mol parts of 1, 4-butanediol relative to 100 mol parts of terephthalic acid.
(2) And (2) continuously adding the slurry prepared in the step (1) into an esterification kettle, carrying out esterification at the temperature of 220 ℃, conveying to a pre-polycondensation system, and finishing polycondensation at the temperature of 240 ℃ to obtain a polyester prepolymer melt with the intrinsic viscosity of 0.3 dL/g.
(3) And conveying the polyester prepolymer melt to a final polycondensation reaction system for final polycondensation reaction at 260 ℃, wherein the precision of a prepolymer melt filter is 10 mu m, and thus obtaining the biodegradable block copolyester melt.
(4) And filtering the obtained biodegradable block copolyester melt by a final polycondensation melt filter, conveying to a casting belt head, molding the casting belt, cooling the casting belt by cooling water, and granulating to obtain the biodegradable block copolyester slice with the intrinsic viscosity of 1.0 dL/g.
The structure and properties of the chips of the biodegradable block copolyesters prepared in examples 1 to 7 and comparative examples 1 to 2 and the composition of the ethylene glycol fraction produced during the continuous preparation were tested.
The test items were as follows:
slice relative viscosity (dL/g) was determined according to test method ASTM D4603-2003.
Section crystallinity (%), test method: measured by a Rigaku D/max 2550VB/PC type X-ray diffractometer, and scanned at a diffraction angle 2 theta of 5-60 degrees by a Cu Ka radiation source, a current of 40mA, a working voltage of 40KV and a scanning frequency of 2 DEG/min.
The sequence length of aromatic dibasic acid ester chain segment in copolyester is tested by the following steps: the measurement was carried out on a Bruker AVANCE III 600M nuclear magnetic resonance apparatus (1HNMR:600MHz) using deuterated chloroform CDCl3 as a solvent and tetramethylsilane TMS as an internal standard.
Tetrahydrofuran and 1, 4-butanediol content (%) in the ethylene glycol fraction, test method: and (3) testing by adopting a GCMS-QP2010 Ultra gas chromatograph-mass spectrometer. The test results are shown in Table 1.
Table 1:
as can be seen from Table 1, the sequence length of the aromatic dibasic acid ester segment in the block copolyester chips prepared in examples 1 to 7 was not more than 2. Therefore, the prepared block copolyester has good biodegradability.
The crystallinity of the block copolyester chips prepared in examples 1 to 7 is greater than or equal to 5%. Therefore, in the blowing cooling slow-release crystallization method provided by the invention, the block copolyester can obtain higher crystallinity in the granulation process, and the adhesion of the slices of the block copolyester in the subsequent application process can be effectively avoided.
In comparative example 1, polybutylene succinate was added after esterification and before precondensation. Because polyester oligomer from an esterification system and the poly (butylene succinate) have high ester exchange reaction activity, a large amount of 1, 4-butanediol is dissociated from the poly (butylene succinate) through ester exchange reaction in a pre-polycondensation reaction stage, one part of the dissociated 1, 4-butanediol can be dehydrated and cyclized to generate tetrahydrofuran under a high temperature condition, and the other part of the dissociated 1, 4-butanediol can enter into ethylene glycol fraction.
As can be seen from Table 1, the ethylene glycol fraction collected in the polycondensation stage in comparative example 1 had a tetrahydrofuran content of 0.21% and a 1, 4-butanediol content of 1.4%, i.e., the tetrahydrofuran and 1, 4-butanediol contents in comparative example 1 were high.
In comparative example 2, 1, 4-butanediol was directly added to the polyester slurry, followed by esterification, prepolycondensation, and final polycondensation in this order to obtain a biodegradable block copolyester. Unreacted free 1, 4-butanediol and tetrahydrofuran generated by high-temperature dehydration and cyclization thereof enter the ethylene glycol fraction, resulting in that the tetrahydrofuran content in the ethylene glycol fraction collected in the polycondensation stage in comparative example 2 is as high as 0.64% and the 1, 4-butanediol content is as high as 5.8%.
Therefore, the ethylene glycol fractions of comparative example 1 and comparative example 2 both had higher tetrahydrofuran and 1, 4-butanediol contents, i.e., the obtained ethylene glycol could not be effectively recycled.
The tetrahydrofuran content in the ethylene glycol fraction produced in the continuous preparation process of the biodegradable block copolyester in examples 1 to 7 is not higher than 0.1%, and the 1, 4-butanediol content is not higher than 0.5%, that is, the tetrahydrofuran and 1, 4-butanediol content in the ethylene glycol fraction are very low, so that the purity of the obtained ethylene glycol meets the requirement that the ethylene glycol is directly recycled as a raw material for esterification reaction.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
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| WO2024230709A1 (en) * | 2023-05-10 | 2024-11-14 | 国高材高分子材料产业创新中心有限公司 | Pbet copolyester and preparation method therefor |
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| CN103804664A (en) * | 2013-10-30 | 2014-05-21 | 上海景宇生物科技有限公司 | Biodegradable multi-block structured polyester, and preparation method and use thereof |
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| JPH1180336A (en) * | 1997-09-12 | 1999-03-26 | Teijin Ltd | Block copolyester and its production |
| CN102746493A (en) * | 2012-07-09 | 2012-10-24 | 北京旭阳化工技术研究院有限公司 | Preparation method of all-biological-base poly butylenes succinate (PBS) |
| CN103804664A (en) * | 2013-10-30 | 2014-05-21 | 上海景宇生物科技有限公司 | Biodegradable multi-block structured polyester, and preparation method and use thereof |
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