CN116948224A - Preparation method of high-tensile-strength degradable polyester PEAT film - Google Patents

Preparation method of high-tensile-strength degradable polyester PEAT film Download PDF

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CN116948224A
CN116948224A CN202310554908.6A CN202310554908A CN116948224A CN 116948224 A CN116948224 A CN 116948224A CN 202310554908 A CN202310554908 A CN 202310554908A CN 116948224 A CN116948224 A CN 116948224A
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polyester
peat
transesterification
temperature
tensile strength
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郎美东
胥哲
陈瑞
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East China University of Science and Technology
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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18Manufacture of films or sheets
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/12Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
    • C08G63/16Dicarboxylic acids and dihydroxy compounds
    • C08G63/18Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
    • C08G63/181Acids containing aromatic rings
    • C08G63/183Terephthalic acids
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78Preparation processes
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/02Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
    • Y02W30/50Reuse, recycling or recovery technologies
    • Y02W30/62Plastics recycling; Rubber recycling

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Polyesters Or Polycarbonates (AREA)

Abstract

The invention discloses a preparation method of a high-tensile strength degradable polyester PEAT film, which comprises the following steps: under the protection of nitrogen, dissolving dihydroxyethyl terephthalate and aliphatic components in ethylene glycol, adding an esterification catalyst, mixing, and carrying out transesterification reaction to obtain a transesterification prepolymer; and adding a polycondensation catalyst into the transesterification prepolymer, continuing transesterification under high-temperature vacuum conditions to obtain a polyester product PEAT, granulating to obtain polyester particles, and tabletting at high temperature to obtain the high-tensile-strength degradable polyester PEAT film. According to the invention, the structure and the performance of the copolyester are regulated and controlled by introducing the aliphatic diethyl adipate, so that the mechanical properties of the copolyester are balanced, and the degradability of the copolyester is effectively improved.

Description

Preparation method of high-tensile-strength degradable polyester PEAT film
Technical Field
The invention belongs to the technical field of degradable polyester materials, and particularly relates to a preparation method of a high-tensile-strength degradable polyester PEAT film.
Background
Polyethylene terephthalate (PET) is a linear thermoplastic polyester which is easy to process, has high light transmittance, good chemical stability and good mechanical property, and is widely used as engineering plastic in the fields of polyester fibers, food packaging, plastic films and the like. So far, the annual global production of PET has exceeded 7000 ten thousand tons, becoming the third largest class of plastics next to polyethylene, polypropylene. The demand of PET is very great, however, PET molecular chains have rigid benzene ring structures and strong hydrophobicity, and are difficult to degrade in natural environment, so that the PET molecular chains are classified into non-degradable plastics. Most of the waste PET bottles, films, fibers and other products are subjected to incineration and landfill treatment, so that the waste PET bottles are low in efficiency and severely pollute the natural environment. Meanwhile, due to the promulgation and implementation of regulations such as plastic limiting, degradable environment-friendly polyester attracts more and more attention. Therefore, the recycling and upgrading of the waste PET and the process of converting the waste polyester into the biodegradable polyester are of great significance in protecting natural environment and promoting the development of polyester industry to the green and sustainable development direction.
Because physical recovery is to pulverize the recovered PET into low-quality PET, or directly produce fiber with lower molecular weight by modifying and granulating PET bottle material with high molecular weight, the product still belongs to non-degradable polyester and contains impurities which are not easy to remove. The chemical is realized by depolymerizing polyester into a polymerized monomer or an intermediate by the attack of a micromolecular depolymerizing agent on a macromolecular chain, and then separating and purifying the polyester for reuse. Other components can be introduced in the recycling process to regulate and control the structure and the performance of the polyester.
Adipic acid component is used in common degradable polyester PBAT (polybutylene adipate/terephthalate), is an aliphatic component with certain degradation performance and flexibility, is added into PET for recycling and copolymerization, improves the degradation and rigidity of copolyester, and is prepared into the degradable polyester, and the application requirements of the film are met by regulating the proportion of the two components.
Disclosure of Invention
The invention aims to provide a preparation method of a high-tensile-strength degradable polyester PEAT film.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the first aspect of the invention provides a preparation method of a high-tensile strength degradable polyester PEAT film, which comprises the following steps:
in the first step, the mass ratio is (0.01-0.1): (2-4): 1 (preferably 0.05:4:1), an alcoholysis catalyst, an alcoholysis solvent and PET particles are mixed, stirred at normal pressure and high temperature, and depolymerized to PET polyester to obtain a depolymerized product;
the alcoholysis solvent in the first step is selected from ethylene glycol, butanediol, methanol, etc.
The alcoholysis catalyst in the first step is selected from zinc acetate and DES;
the preparation method of the DES comprises the following steps: mixing methyl urea and zinc chloride according to a molar ratio of 4:1, and stirring at a temperature of 80-100 ℃ (preferably 90 ℃) until the mixture is transparent and uniform, thus obtaining the DES.
Secondly, dissolving, separating and purifying the depolymerized product obtained in the first step to obtain a dihydroxyethyl terephthalate (BHET) monomer;
thirdly, under the protection of nitrogen, dissolving the dihydroxyethyl terephthalate and the aliphatic components prepared in the second step, which are 1 (more preferably (0.8-1.5): 1 and most preferably (1-1.5): 1), into ethylene glycol, adding an esterification catalyst, mixing, and carrying out transesterification reaction at 180-190 ℃ until the distillation amount of alcohol generated in the transesterification process reaches more than 90% of theoretical value to obtain a transesterification reaction end point, thereby obtaining a transesterification prepolymer;
the addition amount of the esterification catalyst accounts for one ten million (preferably four ten million) of the total mass of the dihydroxyethyl terephthalate and the aliphatic components.
The esterification catalyst is selected from antimonous oxide, dibutyl tin oxide, stannous isooctanoate, germanium dioxide and the like.
The aliphatic component is selected from diethyl adipate.
Fourthly, adding a polycondensation catalyst into the transesterification prepolymer obtained in the third step under the protection of nitrogen, and continuing transesterification under the high-temperature vacuum condition to obtain a polyester product PEAT;
the addition amount of the polycondensation catalyst accounts for one ten million (preferably four ten million) of the total mass of the dihydroxyethyl terephthalate and the aliphatic components.
The polycondensation catalyst is selected from tetrabutyl titanate, tetraisopropyl titanate, titanium dioxide, ethylene glycol titanium and the like.
And fifthly, granulating the polyester product PEAT obtained in the fourth step to obtain polyester particles, and tabletting at high temperature to obtain the high-tensile strength degradable polyester PEAT film.
The stirring temperature at normal pressure and high temperature in the first step is 190-230 ℃ (preferably 220 ℃), and the reaction time is 0.5-5 h (preferably 0.5-1.5 h).
The steps of dissolving, separating and purifying in the second step comprise the following steps: adding hot water into the depolymerization product obtained in the first step, wherein the volume ratio of the hot water to the depolymerization product is (20-30): 1 (preferably 25:1), stirring for 0.5-2 h at normal pressure, filtering to remove impurities to obtain a solution containing the dihydroxyethyl terephthalate (BHET), distilling under reduced pressure to remove part of water, concentrating to obtain a depolymerized product obtained in the first step, adding 1/5-1/10 of the total volume of hot water, cooling and crystallizing for 24-48 h, and filtering to obtain the acicular dihydroxyethyl terephthalate monomer.
The temperature of the cooling crystallization in the second step is 0 ℃.
And (3) continuing transesterification under the high-temperature vacuum condition in the fourth step to obtain a polyester product PEAT: stopping introducing nitrogen, sealing the system, gradually heating to 220-240 ℃, gradually reducing the vacuum degree to below 100Pa in the process, and generating a pole climbing effect (namely the pole climbing effect when the polyester is stretched and oriented along a stirring shaft and wound on the shaft in the stirring process) after 1-12 hours, stopping the reaction, introducing nitrogen, discharging, and obtaining the polyester product PEAT.
And (3) high-temperature lamination in the fifth step: the temperature range is 130-150 ℃ (preferably 140 ℃), the pressure range is 5-10 Pa, the prepressing is 1-10 min (preferably 3 min), the air is exhausted for 5-15 times (preferably 10 times), the hot pressing is continued for 1-10 min (preferably 3 min) under the condition that the temperature is 130-150 ℃ (preferably 140 ℃), and the cooling is carried out.
By adopting the technical scheme, the invention has the following advantages and beneficial effects:
according to the invention, the structure and the performance of the copolyester are regulated and controlled by introducing the aliphatic diethyl adipate, so that the mechanical properties of the copolyester are balanced, and the degradability of the copolyester is effectively improved; according to the invention, diethyl adipate is used as an aliphatic adipic acid component, and through transesterification, the generation of water is avoided, the generation of catalyst deactivation in the processing process is reduced to a certain extent, meanwhile, the stability of the copolyester reaction is ensured, and the dispersion degree of the copolyester is improved, so that the mechanical property is improved to a certain extent, and the heat resistance and the degradability of the copolyester are ensured.
Drawings
FIG. 1 is a nuclear magnetic spectrum of the polyester product PEAT.
Detailed Description
In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.
Example 1
A preparation method of a high-tensile strength degradable polyester PEAT film comprises the following steps:
firstly, mixing an alcoholysis catalyst DES (methyl urea and zinc chloride in a molar ratio of 4:1 and stirring to be transparent and uniform at a temperature of 90 ℃ to obtain 0.25g of DES), 20g of ethylene glycol and 5g of PET particles, stirring at a normal pressure and a high temperature, depolymerizing PET polyester, wherein the depolymerization reaction temperature is 220 ℃ and the reaction time is 0.5-1.5 h, and obtaining a depolymerization product;
secondly, dissolving, separating and purifying the depolymerized product obtained in the first step to obtain a dihydroxyethyl terephthalate (BHET) monomer;
the steps of dissolving, separating and purifying in the second step comprise the following steps: adding hot water into the depolymerization product obtained in the first step, stirring the depolymerization product at the volume ratio of 25:1 under normal pressure for 0.5h, filtering to remove impurities to obtain a solution containing dihydroxyethyl terephthalate (BHET), decompressing and distilling to remove part of water, concentrating to 1/5 of the total volume of the depolymerization product obtained in the first step and the added hot water, cooling and crystallizing in a refrigerator at the temperature of 0 ℃ for 24-48 h, and filtering to obtain a needle-shaped dihydroxyethyl terephthalate monomer;
thirdly, under the protection of nitrogen, dissolving dihydroxyethyl terephthalate (25.424 g,0.1 mol) and diethyl adipate (20.225 g,0.1 mol) into 14mL of ethylene glycol, adding 0.01826g of esterification catalyst, namely antimony trioxide, mixing, and carrying out transesterification under the condition that the addition amount of the esterification catalyst accounts for four parts per million of the total mass of dihydroxyethyl terephthalate and aliphatic components and the temperature is 180-190 ℃ until the distillation amount of alcohol generated in the transesterification process reaches more than 90% of theoretical value to be the end point of the transesterification reaction, thereby obtaining a transesterification prepolymer;
and fourthly, adding 0.01826g of a polycondensation catalyst tetrabutyl titanate into the transesterification prepolymer obtained in the third step under the protection of nitrogen, stopping introducing nitrogen, sealing the system, gradually heating to 220-240 ℃, gradually reducing the vacuum degree to below 100Pa in the process, and generating a pole climbing effect (namely the pole climbing effect when the polyester is stretched and oriented along a stirring shaft and wound on the shaft in the stirring process), stopping the reaction, introducing nitrogen, discharging, thereby obtaining the polyester product PEAT.
FIG. 1 is a nuclear magnetic spectrum of the polyester product PEAT. The peak at left figure 4.69 in figure 1 corresponds to structure CH at right figure d 2 (both ends are methylene groups on ethylene glycol to which terephthalic acid units are attached), the peak at 4.53 corresponds to structure CH at right panel e 2 (methylene group near terephthalic acid unit on ethylene glycol having both ends of terephthalic acid unit and adipic acid unit simultaneously attached), peak at 4.42 corresponds to structure CH at right graph f 2 (methylene group near adipic acid unit on ethylene glycol having both ends of terephthalic acid unit and adipic acid unit simultaneously attached), peak at 4.25 corresponds to structure CH at right graph g 2 (both ends are methylene groups on the ethylene glycol to which the adipic acid units are attached). The appearance of four peaks indicates that the two ends of the ethylene glycol are connected with different monomer structures, thereby proving the successful synthesis of the polyester.
And fifthly, granulating the polyester product PEAT obtained in the fourth step to obtain polyester particles, tabletting at high temperature in a die by using an instrument type tablet press, wherein the temperature is 140 ℃, the pressure is 5-10 Pa, the pre-pressing is carried out for 3min, the exhaust is carried out for 10 times, the hot pressing is continued for 3min under the condition that the temperature is 140 ℃, and the cooling is carried out, so that the high-tensile degradable polyester PEAT film with the tensile strength of more than 50MPa is obtained.
Comparative example 1
A preparation process of a high-tensile strength degradable polyester PEAT film comprises the following steps:
mixing terephthalic acid, adipic acid and ethylene glycol according to a molar ratio of 50:50:120, adding the mixture into a reaction vessel, adding antimony trioxide with the total mass of four parts per million of acid for catalysis, and esterifying the system at 180-190 ℃ under the condition of nitrogen until the reaction water yield reaches 90% of a theoretical value. Then adding tetrabutyl titanate catalyst with the total acid content of four parts per million under the protection of nitrogen, stopping introducing nitrogen, sealing the system, gradually heating to 220-240 ℃, and gradually reducing the vacuum degree to below 100Pa in the process to carry out polycondensation reaction. Stopping the reaction after the pole climbing effect occurs, and introducing nitrogen for discharging. And (3) granulating the polyester product to obtain polyester granules. And (3) prepressing for 3min at 140 ℃ in a die by using an instrument type tablet press, exhausting for 10 times, continuously hot-pressing for 3min at 140 ℃, and cooling to obtain the degradable polyester PEAT film.
Comparative example 2
Commercial PBAT pellets (molar ratio of terephthalic acid to adipic acid 50:50) were film pressed. And (3) prepressing for 3min at 140 ℃ in a die by using an instrument type tablet press, exhausting for 10 times, continuously hot-pressing for 3min at 140 ℃, and cooling to obtain the PBAT film.
The samples prepared in example 1 and comparative examples 1-2 were tested for tensile strength and degradation rate in winter for 40 days, and the test results are shown in table 1.
The degradation rate test method comprises the following steps: weighing the mass of the dried polyester film before soil burying, and marking the mass as m 0 Taking out, cleaning and drying the polyester film after 40 days, weighing the mass of the polyester film, and marking the mass as m 1 Through (m) 0 -m 1 )/m 0 The degradation rate can be calculated.
TABLE 1
The results of example 1 and comparative example 1 demonstrate that the use of diethyl adipate instead of adipic acid can effectively increase the tensile strength of the polyester film. The results of example 1 and comparative example 2 demonstrate that the PEAT copolyester prepared by the above method has much higher tensile strength than commercial PBAT.
Example 2
A preparation method of a high-tensile strength degradable polyester PEAT film comprises the following steps:
firstly, mixing an alcoholysis catalyst DES (methyl urea and zinc chloride in a molar ratio of 4:1 and stirring to be transparent and uniform at a temperature of 90 ℃ to obtain 0.25g of DES), 20g of ethylene glycol and 5g of PET particles, stirring at a normal pressure and a high temperature, depolymerizing PET polyester, wherein the depolymerization reaction temperature is 220 ℃ and the reaction time is 0.5-1.5 h, and obtaining a depolymerization product;
secondly, dissolving, separating and purifying the depolymerized product obtained in the first step to obtain a dihydroxyethyl terephthalate (BHET) monomer;
the steps of dissolving, separating and purifying in the second step comprise the following steps: adding hot water into the depolymerization product obtained in the first step, stirring the depolymerization product at the volume ratio of 25:1 under normal pressure for 0.5h, filtering to remove impurities to obtain a solution containing dihydroxyethyl terephthalate (BHET), decompressing and distilling to remove part of water, concentrating to 1/5 of the total volume of the depolymerization product obtained in the first step and the added hot water, cooling and crystallizing in a refrigerator at the temperature of 0 ℃ for 24-48 h, and filtering to obtain a needle-shaped dihydroxyethyl terephthalate monomer;
thirdly, under the protection of nitrogen, dissolving dihydroxyethyl terephthalate (30.5088 g,0.12 mol) and diethyl adipate (16.18 g,0.08 mol) into 14mL of ethylene glycol, adding 0.01867g of esterification catalyst, namely antimony trioxide, mixing, and carrying out transesterification under the condition that the addition amount of the esterification catalyst accounts for four parts per million of the total mass of dihydroxyethyl terephthalate and aliphatic components and the temperature is 180-190 ℃ until the distillation amount of alcohol generated in the transesterification process reaches more than 90% of theoretical value to be the end point of the transesterification reaction, thus obtaining a transesterification prepolymer;
and fourthly, adding 0.01867g of a polycondensation catalyst tetrabutyl titanate into the transesterification prepolymer obtained in the third step under the protection of nitrogen, stopping introducing nitrogen, sealing the system, gradually heating to 220-240 ℃, gradually reducing the vacuum degree to below 100Pa in the process, and generating a pole climbing effect (namely the pole climbing effect when the polyester is stretched and oriented along a stirring shaft and wound on the shaft in the stirring process), stopping the reaction, introducing nitrogen, discharging, thereby obtaining the polyester product PEAT.
And fifthly, granulating the polyester product PEAT obtained in the fourth step to obtain polyester particles, tabletting at high temperature in a die by using an instrument type tablet press, wherein the temperature is 140 ℃, the pressure is 5-10 Pa, the prepressing is carried out for 3min, the exhaust is carried out for 10 times, the hot pressing is continued for 3min under the condition that the temperature is 140 ℃, and the degradable polyester PEAT film is obtained after cooling.
Example 3
A preparation method of a high-tensile strength degradable polyester PEAT film comprises the following steps:
firstly, mixing an alcoholysis catalyst DES (methyl urea and zinc chloride in a molar ratio of 4:1 and stirring to be transparent and uniform at a temperature of 90 ℃ to obtain 0.25g of DES), 20g of ethylene glycol and 5g of PET particles, stirring at a normal pressure and a high temperature, depolymerizing PET polyester, wherein the depolymerization reaction temperature is 220 ℃ and the reaction time is 0.5-1.5 h, and obtaining a depolymerization product;
secondly, dissolving, separating and purifying the depolymerized product obtained in the first step to obtain a dihydroxyethyl terephthalate (BHET) monomer;
the steps of dissolving, separating and purifying in the second step comprise the following steps: adding hot water into the depolymerization product obtained in the first step, stirring the depolymerization product at the volume ratio of 25:1 under normal pressure for 0.5h, filtering to remove impurities to obtain a solution containing dihydroxyethyl terephthalate (BHET), decompressing and distilling to remove part of water, concentrating to 1/5 of the total volume of the depolymerization product obtained in the first step and the added hot water, cooling and crystallizing in a refrigerator at the temperature of 0 ℃ for 24-48 h, and filtering to obtain a needle-shaped dihydroxyethyl terephthalate monomer;
thirdly, under the protection of nitrogen, dissolving dihydroxyethyl terephthalate (20.3392 g,0.08 mol) and diethyl adipate (24.27 g,0.12 mol) into 14mL of ethylene glycol, adding 0.01784g of esterification catalyst, namely antimony trioxide, mixing, and carrying out transesterification under the condition that the addition amount of the esterification catalyst accounts for four parts per million of the total mass of dihydroxyethyl terephthalate and aliphatic components and the temperature is 180-190 ℃ until the distillation amount of alcohol generated in the transesterification process reaches more than 90% of theoretical value to be the end point of the transesterification reaction, thus obtaining a transesterification prepolymer;
and fourthly, adding 0.01784g of a polycondensation catalyst tetrabutyl titanate into the transesterification prepolymer obtained in the third step under the protection of nitrogen, stopping introducing nitrogen, sealing the system, gradually heating to 220-240 ℃, gradually reducing the vacuum degree to below 100Pa in the process, and generating a pole climbing effect (namely the pole climbing effect when the polyester is stretched and oriented along a stirring shaft and wound on the shaft in the stirring process), stopping the reaction, introducing nitrogen, discharging, thereby obtaining the polyester product PEAT.
And fifthly, granulating the polyester product PEAT obtained in the fourth step to obtain polyester particles, tabletting at high temperature in a die by using an instrument type tablet press, wherein the temperature is 140 ℃, the pressure is 5-10 Pa, the prepressing is carried out for 3min, the exhaust is carried out for 10 times, the hot pressing is continued for 3min under the condition that the temperature is 140 ℃, and the degradable polyester PEAT film is obtained after cooling.
Comparative example 3
A preparation process of a high-tensile strength degradable polyester PEAT film comprises the following steps:
mixing dihydroxyethyl terephthalate, adipic acid and ethylene glycol according to a molar ratio of 50:50:120, adding into a reaction vessel, adding antimony trioxide with the total mass of acid for catalysis, and esterifying the system at 180-190 ℃ under the condition of nitrogen until the reaction water yield reaches 90% of a theoretical value. Then adding tetrabutyl titanate catalyst with the total acid content of four parts per million under the protection of nitrogen, stopping introducing nitrogen, sealing the system, gradually heating to 220-240 ℃, and gradually reducing the vacuum degree to below 100Pa in the process to carry out polycondensation reaction. Stopping the reaction after the pole climbing effect occurs, and introducing nitrogen for discharging. And (3) granulating the polyester product to obtain polyester granules. And (3) prepressing for 3min at 140 ℃ in a die by using an instrument type tablet press, exhausting gas for 10 times, continuously hot-pressing for 3min at 140 ℃, and cooling to obtain the degradable polyester PEAT film.
Comparative example 4
A preparation process of a high-tensile strength degradable polyester PEAT film comprises the following steps:
mixing terephthalic acid, diethyl adipate and ethylene glycol according to a molar ratio of 50:50:120, adding the mixture into a reaction vessel, adding antimony trioxide with the total mass of acid to catalyze, and esterifying the system at 180-190 ℃ under the condition of nitrogen until the reaction water yield reaches 90% of a theoretical value. Then adding tetrabutyl titanate catalyst with the total acid content of four parts per million under the protection of nitrogen, stopping introducing nitrogen, sealing the system, gradually heating to 220-240 ℃, and gradually reducing the vacuum degree to below 100Pa in the process to carry out polycondensation reaction. Stopping the reaction after the pole climbing effect occurs, and introducing nitrogen for discharging. And (3) granulating the polyester product to obtain polyester granules. And (3) prepressing for 3min at 140 ℃ in a die by using an instrument type tablet press, exhausting gas for 10 times, continuously hot-pressing for 3min at 140 ℃, and cooling to obtain the degradable polyester PEAT film.
TABLE 2
The aromatic and aliphatic ratios of examples 1, 2 and 3 were 5:5,6:4, and 4:6, respectively, and the results demonstrate that the tensile strength of the polyester film can be improved to some extent by increasing the aromatic unit ratio, but the degradation property is lost to some extent, and the degradation property can be improved to some extent by increasing the aliphatic ratio, but the tensile strength of the polyester is greatly reduced.
The results of example 1, comparative example 3, comparative example 4 and comparative example 1 demonstrate that PEAT prepared by transesterification of both components has higher tensile strength and similar degradation properties than PEAT prepared by transesterification of one component alone, PEAT prepared by esterification of the other component, and PEAT prepared by esterification without transesterification of both components.
The foregoing description is only illustrative of the preferred embodiment of the present invention, and is not to be construed as limiting the invention, but is to be construed as limiting the invention to any and all simple modifications, equivalent variations and adaptations of the embodiments described above, which are within the scope of the invention, may be made by those skilled in the art without departing from the scope of the invention.

Claims (6)

1. The preparation method of the high-tensile strength degradable polyester PEAT film is characterized by comprising the following steps of:
in the first step, the mass ratio is (0.01-0.1): (2-4): 1, mixing an alcoholysis catalyst, an alcoholysis solvent and PET particles, stirring at normal pressure and high temperature, and depolymerizing the PET polyester to obtain a depolymerized product;
the alcoholysis solvent in the first step is selected from ethylene glycol, butanediol and methanol;
the alcoholysis catalyst in the first step is selected from zinc acetate and DES;
secondly, dissolving, separating and purifying the depolymerized product obtained in the first step to obtain a dihydroxyethyl terephthalate monomer;
thirdly, under the protection of nitrogen, dissolving the dihydroxyethyl terephthalate and the aliphatic component prepared in the second step with the molar ratio of (0.5-2) 1 into ethylene glycol, adding an esterification catalyst for mixing, and carrying out transesterification reaction at the temperature of 180-190 ℃ until the distillation amount of alcohol generated in the transesterification process reaches more than 90% of a theoretical value to obtain a transesterification prepolymer;
the addition amount of the esterification catalyst accounts for ten parts per million of the total mass of the dihydroxyethyl terephthalate and the aliphatic components;
the esterification catalyst is selected from antimony trioxide, dibutyl tin oxide, stannous isooctanoate and germanium dioxide;
the aliphatic component is selected from diethyl adipate;
fourthly, adding a polycondensation catalyst into the transesterification prepolymer obtained in the third step under the protection of nitrogen, and continuing transesterification under the high-temperature vacuum condition to obtain a polyester product PEAT;
the addition amount of the polycondensation catalyst accounts for ten parts per million of the total mass of the dihydroxyethyl terephthalate and the aliphatic components;
the polycondensation catalyst is selected from tetrabutyl titanate, tetraisopropyl titanate, titanium dioxide and ethylene glycol titanium;
and fifthly, granulating the polyester product PEAT obtained in the fourth step to obtain polyester particles, and tabletting at high temperature to obtain the high-tensile strength degradable polyester PEAT film.
2. The method for preparing a high tensile strength degradable polyester PEAT film according to claim 1, wherein the stirring temperature at normal pressure and high temperature in the first step is 190-230 ℃ and the reaction time is 0.5-5 h;
the preparation method of the DES comprises the following steps: mixing methyl urea and zinc chloride according to a molar ratio of 4:1, and stirring at 80-100 ℃ until the mixture is transparent and uniform to obtain DES.
3. The method for preparing a high tensile strength degradable polyester pea film according to claim 1, wherein the steps of dissolving, separating and purifying in the second step comprise the steps of: adding hot water into the depolymerization product obtained in the first step, wherein the volume ratio of the hot water to the depolymerization product is (20-30): 1, stirring for 0.5-2 h at normal pressure, filtering to remove impurities to obtain a solution containing the dihydroxyethyl terephthalate, decompressing and distilling to remove part of water, concentrating to 1/5-1/10 of the total volume of the depolymerized product obtained in the first step and added hot water, cooling and crystallizing for 24-48 h, and filtering to obtain the acicular dihydroxyethyl terephthalate monomer.
4. The method for producing a high tensile strength degradable polyester pea film according to claim 3, wherein the temperature of the cooling crystallization in the second step is 0 ℃.
5. The method for preparing the high-tensile strength degradable polyester PEAT film according to claim 1, wherein the step of obtaining the polyester product PEAT by continuous transesterification under the high-temperature vacuum condition in the fourth step is as follows: stopping introducing nitrogen, sealing the system, gradually heating to 220-240 ℃, gradually reducing the vacuum degree to below 100Pa in the process, stopping the reaction after 1-12 hours, and introducing nitrogen for discharging to obtain the polyester product PEAT.
6. The method for producing a high tensile strength degradable polyester pea film according to claim 1, wherein the high temperature lamination in the fifth step: the temperature range is 130-150 ℃, the pressure range is 5-10 Pa, the pre-pressing is 1-10 min, the air is exhausted for 5-15 times, the hot pressing is continued for 1-10 min under the condition of 130-150 ℃, and the cooling is carried out.
CN202310554908.6A 2023-05-17 2023-05-17 Preparation method of high-tensile-strength degradable polyester PEAT film Pending CN116948224A (en)

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