阅读说明：本技术 一种聚(碳酸酯-醚)基生物降解聚酯及其制备方法 (Poly (carbonate-ether) based biodegradable polyester and preparation method thereof ) 是由 张红明 王献红 王佛松 于 2021-09-26 设计创作，主要内容包括：本发明提供了一种聚(碳酸酯-醚)基生物降解聚酯及其制备方法。本发明提供的聚(碳酸酯-醚)基生物降解聚酯,由包括以下质量份组分的原料制得：2350～15000份聚(碳酸酯-醚)二元醇,66～115份芳香族二元酸(酯),72～95份1,6-己二酸,8～16份多官能度交联剂,4～10份1,4-丁二醇,1.5～13份催化剂,0.9～3.5份稳定剂；所述芳香族二元酸(酯)为芳香族二元酸和芳香族二元酸酯中的一种或几种；所述多官能度交联剂为具有3个以上官能团的交联剂；其中,所述官能团选自羧酸基、酸酐基和羟基中的一种或几种。上述聚(碳酸酯-醚)基生物降解聚酯能够有效降低THF含量,且具有优异力学性能和降解性。(The invention provides a poly (carbonate-ether) based biodegradable polyester and a preparation method thereof. The invention provides poly (carbonate-ether) based biodegradable polyester which is prepared from the following raw materials in parts by mass: 2350-15000 parts of poly (carbonate-ether) diol, 66-115 parts of aromatic dibasic acid (ester), 72-95 parts of 1, 6-adipic acid, 8-16 parts of a polyfunctional crosslinking agent, 4-10 parts of 1, 4-butanediol, 1.5-13 parts of a catalyst and 0.9-3.5 parts of a stabilizer; the aromatic dibasic acid (ester) is one or more of aromatic dibasic acid and aromatic dibasic acid ester; the multifunctional crosslinking agent is a crosslinking agent with more than 3 functional groups; wherein, the functional group is selected from one or more of carboxylic acid group, acid anhydride group and hydroxyl group. The poly (carbonate-ether) -based biodegradable polyester can effectively reduce the THF content, and has excellent mechanical properties and degradability.)

1. The poly (carbonate-ether) -based biodegradable polyester is characterized by being prepared from the following raw materials in parts by mass:

the aromatic dibasic acid (ester) is one or more of aromatic dibasic acid and aromatic dibasic acid ester;

the multifunctional crosslinking agent is a crosslinking agent with more than 3 functional groups; wherein, the functional group is selected from one or more of carboxylic acid group, acid anhydride group and hydroxyl group.

2. The poly (carbonate-ether) -based biodegradable polyester according to claim 1, wherein the poly (carbonate-ether) glycol has a number average molecular weight of 3300 to 6400g/mol and a carbonate unit content of 30 to 68 wt%.

3. The poly (carbonate-ether) -based biodegradable polyester according to claim 1, characterized in that said poly (carbonate-ether) glycol is prepared by:

under the action of a catalyst, carrying out polymerization reaction on carbon dioxide and an epoxy compound in the presence of a chain transfer agent to form poly (carbonate-ether) dihydric alcohol;

the epoxy compound is an alkylene oxide or a halogenated alkylene oxide.

4. The poly (carbonate-ether) -based biodegradable polyester according to claim 3, characterized in that said epoxy compound is one or several of ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide and epichlorohydrin.

5. The poly (carbonate-ether) -based biodegradable polyester according to claim 1, wherein the aromatic dibasic acid is selected from one or more of terephthalic acid, isophthalic acid, 2, 7-naphthoic acid and 1, 4-naphthoic acid;

the aromatic dibasic acid ester is an ester derivative formed by the aromatic dibasic acid.

6. The poly (carbonate-ether) -based biodegradable polyester according to claim 1, wherein said polyfunctional crosslinking agent is selected from one or more of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, 1,3, 5-trimellitic acid, 1,2, 4-trimellitic anhydride, 1,2,4, 5-pyromellitic acid and pyromellitic dianhydride.

7. The poly (carbonate-ether) -based biodegradable polyester according to claim 1, characterized in that said catalyst is selected from one or more of tetra-n-butyl titanate, tetra-isopropyl titanate, diethyl zinc, zinc octoate, zinc acetate, zinc oxide and zinc chloride;

the stabilizer is selected from one or more of triethyl phosphite, pentaerythritol diphosphite, bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite, dioctadecyl pentaerythritol diphosphite, tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine.

8. A method for preparing a poly (carbonate-ether) -based biodegradable polyester according to any one of claims 1 to 7, comprising:

a) mixing poly (carbonate-ether) dihydric alcohol, aromatic dibasic acid (ester), 1, 6-adipic acid, a polyfunctional crosslinking agent and a catalyst, and carrying out esterification reaction to obtain a primary esterified substance;

b) mixing the primary esterified substance with 1, 4-butanediol and a stabilizer to continue esterification reaction to obtain an esterified product;

c) and carrying out polycondensation reaction on the esterification product under the vacuum condition to obtain the poly (carbonate-ether) based biodegradable polyester.

9. The preparation method of claim 7, wherein in the step a), the temperature of the esterification reaction is 180-215 ℃ and the time is 1.5-4.5 h;

in the step b), the temperature of the esterification reaction is 180-215 ℃, and the time is 1-2 h;

in the step c), the temperature of the polycondensation reaction is 240-270 ℃.

10. The method of claim 7, wherein the step c) comprises:

firstly, vacuumizing the system and reducing the pressure to a first pressure, raising the reaction temperature to 240-270 ℃, and reacting for 1-2.5 h; continuously vacuumizing and reducing the pressure to a second pressure, and reacting for 0.5-2 h;

the first pressure is 600-1500 Pa;

the second pressure is 10-200 Pa.

Technical Field

The invention relates to the field of organic materials, in particular to poly (carbonate-ether) -based biodegradable polyester and a preparation method thereof.

Background

According to statistics, the yield of plastic products in 1990 s in China is only 550 ten thousand tons, and the yield of the plastic products in 2019 nationwide reaches 8184 ten thousand tons, which is increased by 3.91 percent on year-by-year basis. However, a great deal of plastic products cannot be degraded and recycled after being used and discarded, and cause a great problem of white pollution to the environment, and the plastic products become hot spots of global attention. Various countries have issued a ban policy on disposable products which are difficult to recover and easy to pollute, and the application of biodegradable materials is promoted. The european union stipulates the recycling of organic waste and its compostable disposal, and also stipulates that the use of 10 disposable articles is prohibited and limited in 2021. The invention officially released 'opinions about further strengthening plastic pollution control' by the Federal for improvement in China on 2020, 1 month and 19.A solid waste pollution environmental control law (revised draft) passed by the routine conference of State administration in 2019 clearly encourages the development and production of degradable film coverings and commodity packages in the environment.

The productivity of the global biodegradable plastic is about 100 ten thousand tons, wherein the global production capacity of bio-based polyester (comprising poly adipic acid-butanediol terephthalate (PBAT), poly succinic acid-butanediol ester (PBS), poly succinic acid-butanediol adipate (PBSA) and the like) chemically synthesized by dibasic alcohol dibasic acid is over 40 ten thousand tons/year, and the productivity of China is over 20 ten thousand tons/year. PBAT as a novel biodegradable copolyester is mainly prepared by directly esterifying terephthalic acid or terephthalic acid glycol ester, butanediol and adipic acid serving as raw materials. The material contains a flexible fat chain segment and a rigid aromatic chain segment, so that the polymer molecular chain has good flexibility, and the mechanical properties of the molecule, such as thermal stability, impact property and the like, are ensured. Under certain degradation conditions, PBAT is almost completely degraded by microorganisms, has no harm to the environment, and is widely applied to the fields of packaging, medical treatment, films and the like.

The PBAT is synthesized by handspike et al (Proc. Nature science, Inc., 2013, 27 (3): 289-294) from dimethyl terephthalate, 1, 4-butanediol and 1, 6-adipic acid by direct esterification, and the intrinsic viscosity of the PBAT can reach 0.101 dl/g. Homohui et al (2010, 39 (11): 1273-.

Although there are a lot of documents and patent reports on PBAT, in the production process of PBAT, 1, 4-butanediol will undergo cyclization reaction to generate 10-35% Tetrahydrofuran (THF) byproduct, which not only reduces the yield and improves the production cost, but also increases the energy consumption and further improves the production cost because the byproduct needs to be recovered by a rectifying tower, and more seriously, the production amount of the byproduct is different in each production batch, so that the synthetic ratio of the whole dibasic acid and the dihydric alcohol is difficult to be effectively controlled, and thus the produced PBAT material has poor reproducibility and unstable product quality.

In order to reduce the amount of tetrahydrofuran by-product, the prior art proposes some solutions. For example, patent application CN 111087593 reports a catalyst composition for inhibiting THF formation and hydrolysis, its preparation method and application, the amount of THF generated by-products is reduced by using a novel catalyst composition comprising a reaction product of a titanium compound with high catalytic activity and hydrolysis resistance and an alcohol containing at least two hydroxyl groups, a hydroxycarboxylic acid and a base, the method is suitable for reducing the amount of THF generated during the synthesis of polybutylene terephthalate (PBT) and PBAT, however, the THF generated amount (calculated according to the addition amount of 1, 4-butanediol) is only reduced from 21% to 18%, and is still very high.

Disclosure of Invention

In view of the above, the present invention aims to provide a poly (carbonate-ether) -based biodegradable polyester and a preparation method thereof. The biodegradable polyester with a novel structure is obtained by the poly (carbonate-ether) based biodegradable polyester and the preparation method, the THF content in the polyester can be effectively reduced, and the biodegradable polyester has high mechanical property and excellent biodegradability.

The invention provides a poly (carbonate-ether) based biodegradable polyester, which is prepared from the following raw materials in parts by mass:

the aromatic dibasic acid (ester) is one or more of aromatic dibasic acid and aromatic dibasic acid ester;

the multifunctional crosslinking agent is a crosslinking agent with more than 3 functional groups; wherein, the functional group is selected from one or more of carboxylic acid group, acid anhydride group and hydroxyl group.

Preferably, the number average molecular weight of the poly (carbonate-ether) glycol is 3300-6400 g/mol, and the carbonate unit content is 30 wt% -68 wt%.

Preferably, the poly (carbonate-ether) glycol is prepared by:

under the action of a catalyst, carrying out polymerization reaction on carbon dioxide and an epoxy compound in the presence of a chain transfer agent to form poly (carbonate-ether) dihydric alcohol;

the epoxy compound is an alkylene oxide or a halogenated alkylene oxide.

Preferably, the epoxy compound is one or more of ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide and epichlorohydrin.

Preferably, the aromatic dibasic acid is selected from one or more of terephthalic acid, isophthalic acid, 2, 7-naphthoic acid and 1, 4-naphthoic acid;

the aromatic dibasic acid ester is an ester derivative formed by the aromatic dibasic acid.

Preferably, the polyfunctional crosslinking agent is one or more selected from tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, 1,3, 5-trimellitic acid, 1,2, 4-trimellitic anhydride, 1,2,4, 5-pyromellitic acid and pyromellitic dianhydride.

Preferably, the catalyst is selected from one or more of tetra-n-butyl titanate, tetra-isopropyl titanate, diethyl zinc, zinc octoate, zinc acetate, zinc oxide and zinc chloride;

the stabilizer is selected from one or more of triethyl phosphite, pentaerythritol diphosphite, bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite, dioctadecyl pentaerythritol diphosphite, tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine.

The invention also provides a preparation method of the poly (carbonate-ether) based biodegradable polyester in the technical scheme, which comprises the following steps:

a) mixing poly (carbonate-ether) dihydric alcohol, aromatic dibasic acid (ester), 1, 6-adipic acid, a polyfunctional crosslinking agent and a catalyst, and carrying out esterification reaction to obtain a primary esterified substance;

b) mixing the primary esterified substance with 1, 4-butanediol and a stabilizer to continue esterification reaction to obtain an esterified product;

c) and carrying out polycondensation reaction on the esterification product under the vacuum condition to obtain the poly (carbonate-ether) based biodegradable polyester.

Preferably, in the step a), the temperature of the esterification reaction is 180-215 ℃ and the time is 1.5-4.5 h;

in the step b), the temperature of the esterification reaction is 180-215 ℃, and the time is 1-2 h;

in the step c), the temperature of the polycondensation reaction is 240-270 ℃.

Preferably, the step c) comprises: firstly, vacuumizing the system and reducing the pressure to a first pressure, raising the reaction temperature to 240-270 ℃, and reacting for 1-2.5 h; continuously vacuumizing and reducing the pressure to a second pressure, and reacting for 0.5-2 h; the first pressure is 600-1500 Pa; the second pressure is 10-200 Pa.

The invention takes poly (carbonate-ether) dihydric alcohol, aromatic dibasic acid (ester), 1, 6-adipic acid and 1, 4-butanediol as reaction raw materials, adopts a certain poly (carbonate-ether) dihydric alcohol area to replace part of the 1, 4-butanediol, and is matched with other specific raw materials to synthesize novel polyester different from PBAT, and the polyester has good mechanical tensile property and biodegradability; in addition, the introduction of the poly (carbonate-ether) diol greatly reduces the usage amount of 1, 4-butanediol, further greatly reduces the generation probability of tetrahydrofuran byproducts, and provides a new thought and a synthesis route for a production method of novel high-quality biodegradable polyester with low tetrahydrofuran byproducts.

Experimental results show that the poly (carbonate-ether) based biodegradable polyester provided by the invention has THF content below 4.5% and lower byproduct amount; the melt index is below 4.5g/10min, which is beneficial to improving the processing performance of the material; the acid value is below 0.3 mgKOH/g; the intrinsic viscosity is more than 1.0dL/g, the number average molecular weight Mn is more than 62kg/mol, and the weight average molecular weight is more than 98kg/mol, so that the mechanical property and the processability of the material are improved; the tensile strength of the material is more than 22MPa, the elongation at break is more than 1180%, and the material shows excellent tensile mechanical properties; the material has the degradation rate of more than 44% at the time of biodegradation for 30 days, the degradation rate of more than 68% at the time of 90 days and the degradation rate of more than 90% at the time of 180 days, and shows excellent biodegradability.

Detailed Description

The invention provides a poly (carbonate-ether) based biodegradable polyester, which is prepared from the following raw materials in parts by mass:

the aromatic dibasic acid (ester) is one or more of aromatic dibasic acid and aromatic dibasic acid ester;

the multifunctional crosslinking agent is a crosslinking agent with more than 3 functional groups; wherein, the functional group is selected from one or more of carboxylic acid group, acid anhydride group and hydroxyl group.

The invention takes poly (carbonate-ether) dihydric alcohol, aromatic dibasic acid (ester), 1, 6-adipic acid and 1, 4-butanediol as reaction raw materials to synthesize novel polyester different from PBAT, and the polyester has good mechanical tensile property and biodegradability; moreover, the introduction of the poly (carbonate-ether) diol greatly reduces the usage amount of 1, 4-butanediol, thereby greatly reducing the generation probability of tetrahydrofuran byproducts.

According to the invention, the poly (carbonate-ether) diol is a polymer containing 2 hydroxyl functional groups, in particular a polymer containing 2 terminal hydroxyl functional groups. In the present invention, the kind of the poly (carbonate-ether) glycol is preferably: poly (carbonate-ether) glycol with the number average molecular weight of 3300-6400 g/mol and the carbonate unit content of 30-68 wt%. Among them, the carbonate unit content is more preferably 30.6 wt% to 67.8 wt%. In some embodiments of the invention, the poly (carbonate-ether) glycol has a number average molecular weight of 3300g/mol, 3500g/mol, 3600g/mol, 5800g/mol, 6000g/mol, or 6400 g/mol. In some embodiments of the invention, the polycarbonate-ether diol has a carbonate unit content of 30.6 wt%, 34.3 wt%, 35.8 wt%, 36.8 wt%, 54.8 wt%, or 67.8 wt%. The poly (carbonate-ether) glycol with the molecular weight range and the carbonate unit content range is adopted, so that the degradation performance and the mechanical performance of the polyester product are improved, and if the number average molecular weight is too low, the rigidity of the obtained polyester product is stronger, and the elongation at break is reduced; if the number average molecular weight is too high, the strength of the polyester product is greatly reduced. If the content of the carbonate unit is too low, the mechanical property of the polyester product is reduced, and the content of ether bond is increased, so that the biodegradation performance is reduced; if the carbonate unit content is too high, the polyester product will be very brittle and have poor toughness.

In some embodiments of the invention, the poly (carbonate-ether) glycol is selected from one or more of the following classes: the number average molecular weight Mn is 3300g/mol, the carbonate unit content is 30.6%; or the number-average molecular weight Mn is 6400g/mol, and the carbonate unit content is 36.8%; or the number average molecular weight Mn is 3500g/mol, and the content of carbonate units is 54.8 percent; or the number average molecular weight Mn is 3600g/mol, and the content of carbonate units is 67.8 percent; or a number-average molecular weight Mn of 5800g/mol and a carbonate unit content of 35.2%; or a number-average molecular weight Mn of 6000g/mol and a carbonate unit content of 34.3%.

In the present invention, the poly (carbonate-ether) glycol is preferably prepared by: under the action of a catalyst, carrying out polymerization reaction on carbon dioxide and an epoxy compound in the presence of a chain transfer agent to form poly (carbonate-ether) dihydric alcohol; wherein the epoxy compound is an alkylene oxide or a halogenated alkylene oxide.

Wherein:

the catalyst is preferably rare earth doped Zn-based₃[Co(CN)₆]₂Double metal cyanide compounds of (a). The epoxy compound is more preferably one or more of ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide and epichlorohydrin. More specifically, said poly (carbonate-ether) glycols are preferably prepared according to the method reported in patent application CN 102432857.

In the invention, the amount of the poly (carbonate-ether) glycol is 2350-15000 parts; in some embodiments of the invention, the poly (carbonate-ether) glycol is used in an amount of 2350 parts, 4850 parts, 6850 parts, 9800 parts, 13500 parts, or 15000 parts.

According to the invention, the aromatic dibasic acid (ester) is one or more of aromatic dibasic acid and aromatic dibasic acid ester. Wherein, the aromatic dibasic acid is preferably one or more of terephthalic acid, isophthalic acid, 2, 7-naphthoic acid and 1, 4-naphthoic acid. The aromatic dibasic acid ester is an ester derivative formed by corresponding to the aromatic dibasic acid, and preferably an ester derivative formed by corresponding to terephthalic acid and/or isophthalic acid; more preferably one or more of dimethyl terephthalate, dioctyl isophthalate and dimethyl isophthalate; most preferred is dimethyl terephthalate and/or dimethyl isophthalate.

In the invention, based on 2350-15000 parts of poly (carbonate-ether) dihydric alcohol, 66-115 parts of aromatic dibasic acid (ester) are used; in some embodiments of the present invention, the aromatic dibasic acid (ester) is used in an amount of 66 parts, 79 parts, 90.5 parts, 95.8 parts, 106 parts, or 115 parts.

According to the invention, the 1, 6-adipic acid is one of the reaction raw materials for the synthesis of the polyester. According to the invention, based on 2350-15000 parts of poly (carbonate-ether) dihydric alcohol, 72-95 parts of 1, 6-adipic acid are used; in some embodiments of the invention, the 1, 6-adipic acid is used in an amount of 72 parts, 81 parts, 84 parts, 89 parts, 91.6 parts, or 95 parts.

According to the invention, the polyfunctional crosslinking agent is a crosslinking agent having more than 3 functional groups; wherein, the functional group is selected from one or more of carboxylic acid group, acid anhydride group and hydroxyl group. The multifunctional crosslinking agent can improve the mechanical property of the polyester product, and if the functionality is too low, the mechanical property of the obtained polyester product is poor. Preferably, the polyfunctional crosslinking agent is one or more selected from tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, 1,3, 5-trimellitic acid, 1,2, 4-trimellitic anhydride, 1,2,4, 5-pyromellitic acid and pyromellitic dianhydride.

In the invention, based on 2350-15000 parts of poly (carbonate-ether) dihydric alcohol, the multifunctional crosslinking agent is 8-16 parts, preferably 8.2-15.6 parts. In some embodiments of the invention, the polyfunctional crosslinking agent is used in an amount of 8.2 parts, 9.6 parts, 10.3 parts, 12.4 parts, 13.8 parts, or 15.6 parts.

According to the invention, the 1, 4-butanediol is one of the reaction raw materials for synthesizing the polyester. In the invention, based on 2350-15000 parts of poly (carbonate-ether) glycol, the 1, 4-butanediol is used in 4-10 parts, preferably 4.8-9.5 parts. In some embodiments of the invention, the 1, 4-butanediol is used in an amount of 4.8 parts, 5.6 parts, 6.8 parts, 8.3 parts, 8.1 parts, or 9.5 parts.

According to the invention, the catalyst is preferably one or more of tetra-n-butyl titanate, tetra-isopropyl titanate, diethyl zinc, zinc octoate, zinc acetate, zinc oxide and zinc chloride. In the invention, based on 2350-15000 parts of poly (carbonate-ether) glycol, the catalyst is used in an amount of 1.5-13 parts, preferably 1.5-12.1 parts. In some embodiments of the invention, the catalyst is used in an amount of 1.5 parts, 2.6 parts, 3.5 parts, 6.8 parts, 11.3 parts, or 12.1 parts.

According to the invention, the stabilizer is preferably one or more of triethyl phosphite, pentaerythritol diphosphite, bis (2, 4-di-tert-butylphenyl) pentaerythritol diphosphite, dioctadecyl pentaerythritol diphosphite, pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] and N, N' -bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine. In the invention, the amount of the stabilizer is 0.9-3.5 parts, preferably 0.9-3.4 parts based on 2350-15000 parts of the amount of the poly (carbonate-ether) glycol. In some embodiments of the invention, the stabilizer is used in an amount of 0.9 parts, 1.2 parts, 1.8 parts, 2.3 parts, or 3.4 parts.

The invention also provides a preparation method of the poly (carbonate-ether) based biodegradable polyester in the technical scheme, which comprises the following steps:

a) mixing poly (carbonate-ether) dihydric alcohol, aromatic dibasic acid (ester), 1, 6-adipic acid, a polyfunctional crosslinking agent and a catalyst, and carrying out esterification reaction to obtain a primary esterified substance;

b) mixing the primary esterified substance with 1, 4-butanediol and a stabilizer to continue esterification reaction to obtain an esterified product;

c) and (3) carrying out polycondensation reaction on the esterification product under vacuum condition to obtain the poly (carbonate-ether) based biodegradable polyester.

The types and the amounts of the poly (carbonate-ether) diol, the aromatic dibasic acid (ester), the 1, 6-adipic acid, the polyfunctional crosslinking agent, the 1, 4-butanediol, the catalyst, the stabilizer and the like are consistent with those in the technical scheme, and are not repeated herein.

Concerning step a)：

In the invention, the mixing mode is not particularly limited, and all materials can be uniformly mixed. After the uniform slurry is obtained by mixing, the obtained slurry is preferably put into a reaction kettle for esterification reaction. In the invention, the temperature of the esterification reaction is preferably 180-215 ℃; in some embodiments of the invention, the temperature of the esterification reaction is 180 ℃, 190 ℃, 195 ℃, 200 ℃, 206 ℃ or 215 ℃. In the invention, the esterification reaction time is preferably 1.5-4.5 h; in some embodiments of the invention, the time for the esterification reaction is 1.5h, 2h, 2.5h, 3.5h, or 4.5 h. In the present invention, the pressure of the esterification reaction is not particularly limited, and may be normal pressure. In the invention, water generated in the esterification reaction is discharged through the water separator device in the esterification reaction process and after the esterification reaction is finished. The primary esterified product is obtained by the esterification reaction.

Concerning step b)：

In the invention, after the primary esterified substance is obtained in the step a), the primary esterified substance is mixed with 1, 4-butanediol and a stabilizer to continue esterification reaction; specifically, 1, 4-butanediol and a stabilizer are added into the reaction kettle in the step a) to continue the esterification reaction. In the invention, the temperature of the esterification reaction is preferably 180-215 ℃; in some embodiments of the invention, the temperature of the esterification reaction is 180 ℃, 190 ℃, 195 ℃, 200 ℃, 206 ℃, or 215 ℃; more preferably, the temperature of the esterification reaction is kept the same as in step a). In the invention, the time of the esterification reaction is preferably 1-2 h; in some embodiments of the invention, the time for the esterification reaction is 1h, 1.5h, or 2 h. In the present invention, the pressure of the esterification reaction is not particularly limited, and may be normal pressure. The esterification product is obtained through the esterification reaction.

Concerning step c)：

In the invention, the temperature of the polycondensation reaction is preferably 240-270 ℃; in some embodiments of the invention, the temperature of the polycondensation reaction is 240 ℃, 250 ℃, 255 ℃, 260 ℃, or 270 ℃. In the invention, the time of the polycondensation reaction is preferably 2.5-3.5 h; in some embodiments of the invention, the time for the polycondensation reaction is 2.5 hours, 3 hours, or 3.5 hours.

In the present invention, the reaction process is specifically preferably: firstly, vacuumizing the system and reducing the pressure to a first pressure, raising the reaction temperature to 240-270 ℃, and reacting for 1-2.5 h; and continuously vacuumizing and reducing the pressure to a second pressure, and reacting for 0.5-2 h. Wherein the first pressure is preferably 600 to 1500Pa, and more preferably 1000 Pa. The reaction time under the first pressure is specifically 1h, 1.5h, 2h and 2.5 h. The second pressure is preferably 10 to 200Pa, and more preferably 50 Pa. The reaction time at the second pressure is specifically 0.5h, 1h, 1.5h or 2 h. The poly (carbonate-ether) -based biodegradable polyester is obtained through the polycondensation reaction.

In the present invention, after the above polycondensation reaction, the reaction product is continuously extruded from the bottom of the reaction vessel, cooled, and pelletized, thereby obtaining the poly (carbonate-ether) -based biodegradable polyester.

In the invention, through the step a), hydroxyl in the structure of the poly (carbonate-ether) diol, carboxylic acid group (hydroxyl or acid anhydride group) of the polyfunctional crosslinking agent and carboxylic acid (ester) group of the aromatic dibasic acid (ester) and 1, 6-adipic acid are subjected to esterification reaction to generate carboxyl (ester) terminated prepolymer; carrying out esterification reaction on the carboxyl (ester) group of the prepolymer obtained in the step a) and the hydroxyl group of 1, 4-butanediol to obtain a macromolecular prepolymer containing hydroxyl and carboxyl (ester) groups; finally, the step c) is carried out, and under the vacuum condition, esterification polycondensation reaction is further carried out between the hydroxyl and the carboxyl of the macromolecular prepolymer obtained in the step b), so as to obtain the poly (carbonate-ether) biodegradable polyester.

In the invention, poly (carbonate-ether) dihydric alcohol, aromatic dibasic acid (ester), 1, 6-adipic acid and 1, 4-butanediol are used as reaction raw materials to synthesize novel polyester different from PBAT, and the polyester has good mechanical tensile property and biodegradability; in addition, the introduction of the poly (carbonate-ether) diol greatly reduces the usage amount of 1, 4-butanediol, further greatly reduces the generation probability of tetrahydrofuran byproducts, and provides a new thought and a synthesis route for a production method of novel high-quality biodegradable polyester with low tetrahydrofuran byproducts.

Experimental results show that the poly (carbonate-ether) based biodegradable polyester provided by the invention has THF content below 4.5% and lower byproduct amount; the melt index is below 4.5g/10min, which is beneficial to improving the processing performance of the material; the acid value is below 0.3 mgKOH/g; the intrinsic viscosity is more than 1.0dL/g, the number average molecular weight Mn is more than 62kg/mol, and the weight average molecular weight is more than 98kg/mol, so that the mechanical property and the processability of the material are improved; the tensile strength of the material is more than 22MPa, the elongation at break is more than 1180%, and the material shows excellent tensile mechanical properties; the material has the degradation rate of more than 44% at the time of biodegradation for 30 days, the degradation rate of more than 68% at the time of 90 days and the degradation rate of more than 90% at the time of 180 days, and shows excellent biodegradability.

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

Example 1

S1, 2350g of poly (carbonate-ether) diol (CN102432857, example 15, Mn 3300g/mol, 30.6% carbonate unit), 66g of terephthalic acid, 72g of 1, 6-adipic acid, 8.2g of citric acid and 1.5g of tetra-n-butyl titanate were mixed to prepare a slurry, which was added to a reaction kettle to perform esterification reaction at 180 ℃, atmospheric pressure and 4.5 hours, and water produced by the reaction was discharged through a rectification apparatus.

S2, adding 4.8g of 1, 4-butanediol and 0.9g of triethyl phosphite into the reaction kettle, and continuing the esterification reaction at the same temperature for 2 hours to obtain an esterification product.

And S3, vacuumizing and reducing the pressure until the system pressure is 1000Pa, gradually increasing the reaction temperature to 240 ℃, reacting for 2.5 hours, continuously vacuumizing and reducing the pressure until the system pressure is 50Pa, reacting for 0.5 hour, stopping the reaction, continuously extruding the reaction product from the bottom of the polymerization kettle, cooling and granulating.

Example 2

S1, 15000g of poly (carbonate-ether) diol (CN102432857, example 9, Mn 6400g/mol, 36.8 wt% carbonate unit content), 115g of isophthalic acid, 95g of 1, 6-adipic acid, 15.6g of trimethylolpropane and 12.1g of tetraisopropyl titanate were mixed to prepare a slurry, which was charged into a reaction vessel to carry out esterification reaction at 215 ℃, normal pressure and 1.5 hours, and water produced by the reaction was discharged through a rectifying apparatus.

S2, adding 9.5g of 1, 4-butanediol and 3.4g of pentaerythritol diphosphite into the reaction kettle, and continuing the esterification reaction at the same temperature for 2 hours to obtain an esterification product.

And S3, vacuumizing and reducing the pressure to 1000Pa, gradually increasing the reaction temperature to 270 ℃, reacting for 1 hour, continuously vacuumizing and reducing the pressure to 50Pa, reacting for 2 hours, stopping the reaction, continuously extruding the reaction product from the bottom of the polymerization kettle, cooling and granulating.

Example 3

S1, 4850g of poly (carbonate-ether) diol (CN102432857, example 17, Mn 3500g/mol, 54.8% carbonate unit), 79g of dimethyl terephthalate, 81g of 1, 6-adipic acid, 9.6g of pentaerythritol and 2.6g of diethyl zinc were mixed to prepare a slurry, which was added to a reaction kettle to perform esterification reaction at 190 ℃, pressure and time of 2 hours under normal pressure, and water produced by the reaction was discharged through a rectifying apparatus.

S2, adding 5.6g of 1, 4-butanediol and 1.2g of dioctadecyl pentaerythritol diphosphite into the reaction kettle, and continuing the esterification reaction at the same temperature for 1.5 hours to obtain an esterification product.

S3, vacuumizing and reducing the pressure to 1000Pa, gradually increasing the reaction temperature to 250 ℃, reacting for 2 hours, continuously vacuumizing and reducing the pressure to 50Pa, reacting for 1 hour, stopping the reaction, continuously extruding the reaction product from the bottom of the polymerization kettle, cooling and granulating.

Example 4

S1, 6850g of poly (carbonate-ether) diol (CN102432857, example 18, Mn 3600g/mol, 67.8% carbonate unit), 90.5g of 2, 7-naphthoic acid, 84g of 1, 6-adipic acid, 10.3g of 1,3, 5-trimellitic acid, and 3.5g of zinc octoate were mixed to prepare a slurry, which was added to a reaction vessel to perform an esterification reaction at 195 ℃.

S2, adding 6.8g of 1, 4-butanediol and 1.8g of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester into the reaction kettle, and continuing the esterification reaction at the same temperature for 1 hour to obtain an esterified product.

S3, vacuumizing and reducing the pressure to 1000Pa, gradually increasing the reaction temperature to 260 ℃, reacting for 1.5 hours, continuously vacuumizing and reducing the pressure to 50Pa, reacting for 1 hour, stopping the reaction, continuously extruding the reaction product from the bottom of the polymerization kettle, cooling and granulating.

Example 5

S1, 9800g of poly (carbonate-ether) glycol (CN102432857, example 12, Mn: 5800g/mol, 35.2% carbonate unit), 95.8g of dimethyl terephthalate, 89g of 1, 6-adipic acid, 12.4g of malic acid and 6.8g of zinc acetate were mixed to prepare a slurry, which was added to a reaction kettle to perform esterification reaction at 200 ℃, normal pressure and 2 hours, and water produced by the reaction was discharged through a rectifying apparatus.

S2, adding 8.3g of 1, 4-butanediol and 2.3g of pentaerythritol diphosphite into the reaction kettle, and continuing the esterification reaction at the same temperature for 1.5 hours to obtain an esterification product.

And S3, vacuumizing and reducing the pressure to 1000Pa, gradually increasing the reaction temperature to 255 ℃, reacting for 2 hours, continuously vacuumizing and reducing the pressure to 50Pa, reacting for 1.5 hours, stopping the reaction, continuously extruding the reaction product from the bottom of the polymerization kettle, cooling and granulating.

Example 6

S1, 13500g of poly (carbonate-ether) diol (CN102432857, example 8, Mn 6000g/mol, 34.3% carbonate unit), 106g of isophthalic acid, 91.6g of 1, 6-adipic acid, 13.8g of trimethylolethane, and 11.3g of zinc chloride were mixed to prepare a slurry, which was charged into a reaction kettle to perform esterification reaction at 205 ℃, normal pressure, and 3.5 hours, and water produced by the reaction was discharged through a rectifying apparatus.

S2, adding 8.1g of 1, 4-butanediol and 2.8g of pentaerythritol diphosphite into a reaction kettle, and continuing esterification reaction at the same temperature for 1.5 hours to obtain an esterification product;

s3, vacuumizing and reducing the pressure to 1000Pa, gradually increasing the reaction temperature to 260 ℃, reacting for 1.5 hours, continuously vacuumizing and reducing the pressure to 50Pa, reacting for 1.5 hours, stopping the reaction, continuously extruding the reaction product from the bottom of the polymerization kettle, cooling and granulating.

Comparative example 1

The procedure of example 1 was followed except that 2350g of the poly (carbonate-ether) diol in step S1 was replaced with 126.5g of 1, 4-butanediol.

Comparative example 2

The procedure of example 1 was followed except that 15000g of the poly (carbonate-ether) diol in step S1 was replaced with 185g of 1, 4-butanediol.

Example 7: product testing

The properties and performance of the products obtained in examples 1-6 and comparative examples 1-2 were tested and the results are shown in tables 1 and 2, respectively.

Wherein:

the THF content (i.e., tetrahydrofuran by-product content) was calculated from the ratio of the amount of THF produced/the amount of 1, 4-butanediol added. The test of the melt index is carried out according to GB/T32366-; the melt index may reflect the processability of the material to some extent. The intrinsic viscosity test was performed according to GB/T12005.1-1989. The testing of acid number was performed according to GB/T2895-2008.

Testing of biodegradability: reference is made to GB/T19277.1-2011. The final aerobic biological decomposition and disintegration ability of biodegradable polyurethane elastomers under controlled composting conditions was investigated. In a 2L test system, the test mixture was aerated at a controlled rate with carbon dioxide free air using polyester as the organic carbon source. The degradation rate was determined by measuring the amount of carbon dioxide produced.

The specific operation of the biodegradability test is as follows: 40g of the polyester products obtained in examples 1 to 6 and comparative examples 1 to 2 were respectively prepared into polyester films having a thickness of 10 μm. 240g of culture soil was mixed with the polyester film thus produced and 40g of microcrystalline cellulose to prepare a test specimen. Meanwhile, 240g of culture soil was used as a blank control. The humidity of the material was adjusted to 50% by adding distilled water to each of the test sample and the blank control sample. Placing the compost container in a test environment at (58 +/-2) DEG C, and using CO-free₂The test system was aerated at a flow rate of 0.05L/min with saturated air at a temperature of (58. + -. 2) ℃ and the test was carried out. According to the carbon dioxide actually produced by the test material during the testThe ratio of the amount to the theoretical amount of carbon dioxide released from the test material was taken as the biodegradation rate of the test material. It was found experimentally that disintegration of the material had occurred at 30d (i.e. 30 days) and the degradation rates at different stages are shown in table 2.

TABLE 1 product characteristics of examples 1-6 and comparative examples 1-2

TABLE 2 Properties of the products of examples 1 to 6 and comparative examples 1 to 2

As can be seen from the test results in tables 1-2, the following properties are improved in examples 1-6 of the present invention as compared to comparative examples 1-2: the THF content is obviously reduced, namely the amount of tetrahydrofuran byproducts is greatly reduced; the melt index is reduced, thereby being beneficial to improving the processing performance of the material; the intrinsic viscosity, the number average molecular weight and the weight average molecular weight of the material are obviously improved, and the mechanical property and the processability of the material are improved; the tensile strength and the elongation at break of the material are obviously improved, and the test results of the intrinsic viscosity and the molecular weight are verified. The material has the degradation rate of more than 44% after being biodegraded for 30 days, the degradation rate of more than 68% after 90 days, the degradation rate of more than 90% after 180 days, and the biodegradability is obviously improved.

The foregoing examples are provided to facilitate an understanding of the principles of the invention and their core concepts, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention. The scope of the invention is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that approximate the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.