CN111116882B

CN111116882B - Full-biodegradable copolyester and preparation method and application thereof

Info

Publication number: CN111116882B
Application number: CN202010005648.3A
Authority: CN
Inventors: 乌婧; 林一鸣; 王华平
Original assignee: Donghua University
Current assignee: Donghua University
Priority date: 2020-01-03
Filing date: 2020-01-03
Publication date: 2021-03-26
Anticipated expiration: 2040-01-03
Also published as: CN111116882A

Abstract

The invention relates to a full-biodegradable copolyester, a preparation method and application thereof, wherein the preparation method comprises the following steps: firstly, with A₁、B₁And B₂The raw materials are subjected to a first-stage reaction under the condition of high temperature (more than or equal to 190 ℃) and the action of a first catalyst, and then a first-stage product, a rigid monomer (IHDCA or IHDXC) and A are used₂The raw materials are subjected to a second-stage reaction under the low-temperature condition and the action of a second catalyst, and finally, a polycondensation reaction is carried out to prepare the fully biodegradable copolyester; the copolyester is used for preparing fully biodegradable copolyester fibers, high-light-transmittance fully biodegradable copolyester films and plasticized fully biodegradable copolyester films; the prepared product has excellent performance, the invention effectively solves the problems of serious IHDCA or IHDXC degradation and low molecular weight of a polymerization product, and the copolyester is applied to the fields of fibers and films.

Description

Full-biodegradable copolyester and preparation method and application thereof

Technical Field

The invention belongs to the technical field of high polymer materials, relates to a fully biodegradable copolyester, and a preparation method and application thereof, and particularly relates to a fully biodegradable copolyester based on IHDCA or IHDXC, and a preparation method and application thereof.

Background

In recent years, the preparation of novel polymers by using carbohydrates attracts extensive attention at home and abroad, wherein isohexides (isohexides) and derivative monomers thereof are the most widely researched carbohydrate-based monomers, and the molecules have a unique cyclic ether skeleton structure, so that the polymer has high structural rigidity and hydrophilicity, and is expected to improve the thermal or mechanical properties and the biodegradability of the polymer. Since the 80 th century, isohexide has been widely used by scholars at home and abroad to synthesize various polymers such as polyester, polyamide, polycarbonate and polyurethane.

At present, one outstanding difficulty in synthesizing polyester by utilizing isohexide is that two hydroxyl groups in the structure are secondary hydroxyl groups, and the polyester has lower reaction activity in melt polymerization, so that the synthesized polyester has low molecular weight, and the serious yellowing caused by the thermal degradation of the polymer is aggravated by prolonging the reaction time or increasing the reaction temperature, thereby causing the chromaticity of the polyester product to be poor; the method using solution or interfacial polymerization requires the use of a large amount of solvent or reagent, which is not favorable for large-scale industrial production. In order to overcome the above problems, a new monomer, i.e., isohexide-2,5-dicarboxylic acid (IHDCA) and its alkyl ester derivative, methyl isohexide-2, 5-dicarboxylate (IHDXC), has been developed in recent years, which is prepared from isohexide as a raw material through hydroxyl-enhanced carbonization. IHDCA contains three isomers, depending on the steric conformation of the carboxyl function, namely: isoidide-2,5-dicarboxylic acid (IIDCA), isomannide-2,5-dicarboxylic acid (IMDCA) and isosorbide-2,5-dicarboxylic acid (ISDCA-2, 5-dicarboxylic acid, ISDCA). Compared with the isohexide protomer, the IHDCA and the IHDXC have higher melt polymerization activity, and simultaneously, as the carboxyl functional group is still connected with a ring-shaped framework structure, the IHDCA and the IHDXC still have higher structural rigidity, so that the thermal property of the polyester can be effectively improved (for example, IIDCA or methyl isoidide-2, 5-dicarboxylate IIDMC on T_gThe improvement capability of the copolyester is about 50-70 ℃ higher than that of adipic acid with the same carbon number, so that when the biodegradable polyester is constructed, IHDCA and IHDXC are used for replacing aromatic monomers (terephthalic acid or furan-2, 5-dicarboxylic acid) and aliphatic diol and aliphatic diacid for copolymerization, and theoretically, the copolyester with low aromatic monomer content and even full fat can be prepared. The copolyester not only has higher thermal property than the prior all-aliphatic copolyester (such as PBS, PBAT), but also has more excellent biodegradability.

However, in the process of preparing the above copolyester by the melt polymerization method, since IHDCA and IHDXC have low thermal stability, side reactions such as decarboxylation and crosslinking are likely to occur when the polymerization temperature reaches 150-180 ℃, while the polymerization of aliphatic diol and aliphatic dibasic acid or aromatic dibasic acid generally requires a high reaction temperature (>200 ℃), although related documents have reported a preparation method for synthesizing homopolyester by IIDCA/IIDMC and linear alkane diol, when copolymerization is performed by using such monomers and aliphatic diol and aliphatic dibasic acid/aromatic dibasic acid, there are problems that multi-component effective copolymerization, severe degradation of IHDCA or IHDXC, and low molecular weight of polymerization products are difficult to achieve.

Therefore, in order to expand the application range of IHDCA and IHDXC, especially when the IHDCA and IHDXC are prepared into multicomponent copolyester in the form of comonomer, a method capable of effectively solving the above problems needs to be found, and simultaneously, the prepared copolyester is further regulated and controlled by the process to improve the processability thereof, so that the copolyester can be processed into fiber and film products for use by using the existing application technology.

Disclosure of Invention

The invention aims to solve the problems that effective copolymerization of multiple components is difficult to realize, thermal degradation is serious and the molecular weight of a polymerization product is low when IHDCA or IHDXC is used for preparing biodegradable copolyester in the prior art, and provides the fully biodegradable copolyester based on the IHDCA or the IHDXC and a preparation method and application thereof.

According to the invention, by regulating and controlling the technological conditions of comonomer esterification or ester exchange reaction, the high-efficiency copolymerization of multiple components is realized, and the problems of serious high-temperature thermal degradation of IHDCA or IHDXC and low molecular weight of products caused by insufficient esterification rate of aliphatic diol and aliphatic dibasic acid or aromatic dibasic acid due to low reaction temperature are effectively solved.

The fully biodegradable copolyester fiber provided by the invention has the moisture regain of more than or equal to 3.0 percent, the surface contact angle of less than or equal to 70 degrees, excellent hydrophilicity, good biodegradability and mechanical strength of more than or equal to 2cN/dtex, and can be applied to the fields of home textiles, clothes, disposable medical and health materials and the like.

The fully biodegradable copolyester provided by the invention has higher glass transition temperature and excellent biodegradability, so that the fully biodegradable copolyester has certain flexibility and film-forming property, is favorable for further preparing a film to expand the application range of the film, and improves the optical property and mechanical property of the film by mixing a certain amount of plasticizer and inorganic nano filler in the copolyester, thereby preparing the fully biodegradable copolyester film with better comprehensive performance and further expanding the market competitiveness of the film.

The fully biodegradable copolyester provided by the invention has high content of aliphatic components, low proportion of aromatic petroleum-based monomers and excellent biodegradability, and the toughness and mechanical properties of the fully biodegradable copolyester are further improved by adding a certain amount of cross-linking agent in the melt extrusion process, so that a plasticized fully biodegradable copolyester film with better comprehensive performance is prepared, and the application value of the fully biodegradable copolyester film is further improved.

In order to achieve the purpose, the invention adopts the following scheme:

a process for preparing full-biodegradable copolyester₁、B₁And B₂The raw materials are subjected to a first-stage reaction under the action of a first catalyst under the condition of high temperature, and then a first-stage product, a rigid monomer and A are used₂The raw materials are subjected to a second-stage reaction under the low-temperature condition and the action of a second catalyst, and finally, a polycondensation reaction is carried out to prepare the fully biodegradable copolyester;

the first stage reaction and the second stage reaction are esterification or ester exchange reaction;

the molar amount of the rigid monomer is B₁、B₂And 1-48% of the sum of the molar weight of the rigid monomer;

A₁and A₂Is a fatty diol, the two being the same or different, B₁Is an aromatic dicarboxylic acid and/or an alkyl ester thereof, added in an amount of 0 or other than 0, B₂Is a fatty dicarboxylic acid and/or alkyl ester thereof, and the rigid monomer is IHDCA or IHDXC, the IHDCA comprising three isomers, namely: isoidide-2,5-dicarboxylic acid (IIDCA), isomannide-2,5-dicarboxylic acid (IMDCA) and isosorbide-2,5-dicarboxylic acid (ISOMANNIde-2,5-dicarboxylic acid, IMDCA), IHDXC is a methyl ester derivative of IHDCA, also including three isomers, the type of rigid monomer of the invention is not limited to these, other alkanes of IHDCAThe alkyl ester (C2-18 alkyl ester) is also suitable for the invention;

the first catalyst is used for realizing the reaction of the aliphatic diol (A) comprising a certain equivalent weight₁) Aromatic dicarboxylic acid and/or alkyl ester thereof (B)₁) Aliphatic dicarboxylic acid and/or alkyl ester thereof (B)₂) The monomers in the reactor are subjected to esterification or ester exchange reaction to accelerate the reaction process; the second catalyst is used for realizing the reaction of IHDCA or IHDXC and a certain equivalent of aliphatic diol (A)₂) The monomers in the polyester prepolymer undergo esterification or ester exchange reaction to accelerate the reaction process, and researches show that dibutyltin oxide, butylstannic acid, stannous octoate, stannous 2-ethylhexanoate and tetrabutyl titanate can prepare polyester with higher molecular weight in the second-stage reaction;

the high temperature is 190 ℃ or higher, and the low temperature is lower than the temperature of the rigid monomer at the beginning of thermal degradation side reaction, wherein the thermal degradation side reaction comprises ring-opening reaction, crosslinking reaction and the like.

In the prior art, IIDCA or IIDMC is used for polymerization, one method is to prepare homopolyester (cellulose isocyanate-Based Polyesters: Synthesis, chromatography, and Structure-Properties relationships.) under the condition of melt polymerization reaction (Semicristalline Polyesters Based on a Novel connectable Building Block.), the reaction temperature is low, and A cannot be realized₁、B₁And B₂High esterification rate or high ester exchange rate of component (C<60%), low molecular weight of the polymer product, another method is an enzyme-catalyzed polymerization in solution systems (Isohexide and sorbent-eliminated, enzymationally Synthesized recycled Polyesters with Enhanced Tg), long reaction times, and very low molecular weight of the polymer product: number average molecular weight Mn<1800g/mol；

The preparation method of the full-biodegradable copolyester of the invention comprises two stages of esterification or ester exchange reaction, and the main reason is that A₁、B₁And B₂The esterification reaction or ester exchange reaction of the components can be carried out more effectively under the condition that the temperature is more than or equal to 190 ℃ (conversion rate)>90%) and in this temperature range the oxygen heterocycle of IHDCA or IHDXC is liable to be disengagedCarboxyl, and ring-opening thermal degradation reaction to further initiate polymer branching or crosslinking side reaction, so that IHDCA or IHDXC is not added in the first stage for realizing A₁、B₁And B₂High esterification rate or high ester exchange rate of the components, and the purpose of the second stage is mainly to ensure that the IHDCA or IHDXC and A are newly added₂The esterification or ester exchange reaction can be carried out at a lower temperature, so that the occurrence of thermal degradation side reaction is avoided; if the IHDCA or IHDXC is thermally degraded under the high temperature condition when all monomers are added in one step instead of adopting the two-step method, the hydroxyl-carboxyl ratio in the system is unbalanced, the gelation phenomenon can occur, or the high polymer can not be prepared; at relatively low temperatures, however, the molecular weights are correspondingly low due to the low esterification or transesterification rates, and multicomponent copolymerization is difficult to achieve.

As a preferable scheme:

a process for preparing the fully biodegradable copolyester as described above, A₁Or A₂Is one or more of ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 2-butylene glycol, 1, 3-butylene glycol, 1, 4-butylene glycol, 2, 3-butylene glycol, 1, 5-pentanediol, 1, 4-pentanediol, 2, 4-pentanediol, 1, 6-hexanediol, 1, 5-hexanediol, 1, 4-hexanediol, 2, 5-hexanediol, and 3, 4-hexanediol.

A process for preparing the fully biodegradable copolyester, B₁Is more than one of terephthalic acid, phthalic acid, isophthalic acid, 1, 8-naphthalene dicarboxylic acid, 2, 6-naphthalene dicarboxylic acid, furan-2, 5-dicarboxylic acid, furan-2, 4-dicarboxylic acid and furan-3, 4-dicarboxylic acid;

B₂is more than one of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, maleic acid, fumaric acid, glutaconic acid, callus acid, muconic acid, itaconic acid and substance C, and the chemical molecular formula of the substance C is HOOC- (CHOH)_n-COOH, n is 2,3 or 4;

the first catalyst is a titanium catalyst, an antimony catalyst or a metal acetate, the titanium catalyst is tetrabutyl titanate or tetraisopropyl titanate, the antimony catalyst is antimony trioxide, and the metal acetate is more than one of zinc acetate, magnesium acetate, manganese acetate, calcium acetate, sodium acetate and cobalt acetate; the second catalyst is a mixture of dibutyltin oxide and stannous octoate; when the first catalyst is a titanium catalyst, the molecular weight of the first-stage product is relatively high; the second catalyst is a mixture of dibutyltin oxide and stannous octoate, and the molecular weight of the product is relatively high when the second catalyst is the mixture of dibutyltin oxide and stannous octoate, mainly because the dibutyltin oxide and the stannous octoate can generate a certain synergistic effect.

A₁Molar amount of (A) and (B)₁And B₂The molar weight ratio of the dibasic alcohol is 1.1-1.5: 1 (in the invention, the dibasic alcohol is excessive to realize the complete esterification of the dibasic acid, the excessive dibasic alcohol can be removed by utilizing subsequent high vacuum to realize the hydroxyl-carboxyl ratio balance, if the dibasic alcohol is excessive, the difficulty of vacuum removal is increased, the reaction time is long, the thermal degradation of the copolyester can be caused, if the dibasic acid is excessive, the excessive dibasic acid is difficult to remove due to high boiling point of the dibasic acid, if the dibasic acid and the dibasic alcohol are strictly added according to the ratio of 1:1, a great amount of the dibasic alcohol is volatilized in the high-temperature polymerization process, the hydroxyl-carboxyl ratio imbalance can be caused, and a high-molecular-weight polymer can not be prepared), B₁In a molar amount of B₁、B₂And 0 to 20% of the sum of the molar amounts of rigid monomers (B)₁Can be added in small or no amount, and the biodegradation is difficult to realize when the amount of the aromatic monomer is too much, and the main purpose of the invention is to reduce the using amount of the aromatic monomer or not add the aromatic monomer), A)₂The molar ratio of the first catalyst to the rigid monomer is 1.01-2.0: 1, and the molar amount of the first catalyst to B₁And B₂The ratio of the sum of the molar weights of the second catalyst and the rigid monomer is 50-2000 ppm (when the catalyst is used too low, effective polymerization cannot be realized, the reaction time is slow, and when the catalyst is used too high, waste is caused), and the ratio of the molar ratio of the second catalyst to the rigid monomer is 50-2000 ppm;

a heat stabilizer and an antioxidant are also added in the first stage reaction or the second stage reaction;

the heat stabilizer is more than one of phosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, ammonium phosphate, trimethyl phosphate, dimethyl phosphate, triphenyl phosphate, diphenyl phosphate, triphenyl phosphite, ammonium phosphite and ammonium dihydrogen phosphate;

the antioxidant is more than one of antioxidant 1010, antioxidant 1076 and antioxidant 1425;

in the first stage reaction, the addition amounts of the heat stabilizer and the antioxidant are respectively A₁、B₁And B₂0.1-2% and 0.1-2% of the total mass;

in the second stage reaction, the heat stabilizer and the antioxidant are added in the amounts of the rigid monomer and A respectively₂0.1-2% and 0.1-2% of the total mass;

in the two-stage reaction process, if the addition amounts of the heat stabilizer and the antioxidant are too low, the heat stabilizer and the antioxidant cannot play a role; too high, it is wasteful.

The temperature of the first-stage reaction is 190-260 ℃, the time is 2-5 hours, the reaction temperature and the reaction time are set to realize effective esterification of the three components in the first stage, the temperature is too low, the time is too short, the high esterification rate cannot be achieved, and the thermal degradation is serious when the temperature is too high and the time is too long; the temperature of the second stage reaction is 130-170 ℃, the time is 2-5 hours, the reaction temperature and the reaction time are set mainly for realizing the esterification of monomers such as IHDCA or IHDXC in the second stage and avoiding thermal degradation, sufficient energy is difficult to provide when the temperature is lower than the temperature or the time is shorter than the temperature, the esterification is incomplete, and the thermal degradation is serious when the temperature is higher than the temperature or the time is longer than the time.

According to the preparation method of the fully biodegradable copolyester, the first-stage reaction also comprises a prepolymerization reaction after esterification or ester exchange reaction, wherein the temperature of the prepolymerization reaction is 200-260 ℃, the time is 0.5-2 h, and the pressure is 0.05-100 mbar; the prepolymerization process is a pre-polycondensation reaction process between the first esterification or ester exchange and the second esterification or ester exchange, the prepolymer formed by the first esterification or ester exchange reaction can be subjected to primary polycondensation to form a pre-polycondensation polymer, and the melting point of the pre-polycondensation polymer is relatively low, so that the second esterification or ester exchange is favorably carried out at a lower temperature, and the degradation of rigid monomers is reduced.

According to the preparation method of the fully biodegradable copolyester, a polycondensation reaction is divided into a pre-polycondensation process and a final polycondensation process, the temperature of the pre-polycondensation process is 190-260 ℃, the time is 0.5-2 hours, the pressure is 0.05-100 mbar, the temperature of the final polycondensation process is 150-180 ℃, the time is 2-5 hours, and the pressure is 0.05-1 mbar; the final polycondensation is also mainly used for realizing the polymerization of monomers containing IHDCA or IHDXC, so as to avoid thermal degradation, and the pressure can be gradually reduced to about 0.05mbar from 100mbar at the beginning of the polycondensation.

According to the preparation method of the full-biodegradable copolyester, the temperature of the polycondensation reaction is 190-260 ℃, the time is 0.5-2 hours, and the pressure is 0.05-100 mbar.

The invention also provides the fully biodegradable copolyester prepared by the preparation method of the fully biodegradable copolyester, wherein the molecular chain mainly comprises A₁Chain segment, A₂Segment, B₁Segment, B₂The chain segment and the rigid monomer chain segment are combined, the intrinsic viscosity is 0.51-1.0 dL/g, the intrinsic viscosity of the polyester is characterized by an Ubbelohde viscometer, the number average molecular weight is 18,000-30,000 g/mol, the number average molecular weight of the polyester is characterized by Gel permeation chromatography (Gel permeation chromatography), and the molar weight of the rigid monomer accounts for B in a nuclear magnetic spectrum₁、B₂And the sum of the molar amounts of the rigid monomers in a proportion such that the molar amount of the rigid monomer in the feed is B₁、B₂And the sum of the molar weight of the rigid monomer is 0-4% lower, which indicates that the rigid monomer is effectively grafted into the copolyester molecular chain.

The application of the fully biodegradable copolyester is that the fully biodegradable copolyester is prepared into the fully biodegradable copolyester fiber through melt spinning;

the process flow of the melt spinning processing is as follows: drying, melting a spinning screw, extruding, spinning, cooling, winding and stretching;

the technological parameters of the melt spinning processing are as follows: drying for 10-24 h at a drying temperature of 40-120 ℃, a spinning screw temperature of 140-180 ℃, a spinning speed of 500-1600 m/min, a cooling temperature of 18-26 ℃, a stretching temperature of 50-70 ℃, a pre-stretching ratio of 1.0-1.1, a primary stretching ratio of 2.5-3.0, and a secondary stretching ratio of 1.05-1.15;

the spinning screw is a double screw with a degassing function (air in the melt can be discharged, the spinning efficiency and the uniformity of fibers are improved), and the cooling medium is water;

the fully biodegradable copolyester fiber is short fiber, the titer is 1-3 dtex, and the length is 38mm or 51 mm; the moisture regain of the full-biodegradable copolyester fiber is more than or equal to 3.0 percent, the surface contact angle is less than or equal to 70 degrees, the mechanical strength is more than or equal to 2.0cN/dtex, and the elastic modulus is less than or equal to 70 cN/dtex.

The application of the fully biodegradable copolyester is to blow the fully biodegradable copolyester mixture mainly consisting of the fully biodegradable copolyester, the plasticizer and the inorganic nano filler as master batch to form a film so as to prepare the high-light-transmittance fully biodegradable copolyester film;

the preparation process of the fully biodegradable copolyester mixture comprises the following steps: mixing and stirring uniformly the fully biodegradable copolyester, the plasticizer and the inorganic nano filler in a weight ratio of 100: 10-25: 0-20, and then extruding and granulating;

the plasticizer is more than one of dioctyl sebacate, tributyl citrate, epoxidized soybean oil and trioctyl phosphate, and the inorganic nano filler is nano barium sulfate and/or nano silicon dioxide;

the mixing and stirring temperature is 23-27 ℃, the rotating speed is 150-200 r/min, the time is 10min, and the extrusion granulation temperature is 130-180 ℃;

the nano barium sulfate is a novel inorganic powder synthesized by a chemical method, has the advantages of high specific gravity, high whiteness, excellent optical performance, good chemical stability and the like, is widely used in the fields of various plastics, rubber, coatings, chemical industry, papermaking, ceramics and the like, and can improve the light transmittance, the glossiness, the heat resistance, the wear resistance and the like of products; the nano silicon dioxide is amorphous white powder, is non-toxic, tasteless and pollution-free, has a spherical microstructure, is in a flocculent and reticular quasi-particle structure, has the optical performance of resisting ultraviolet rays, and can improve the optical performance, ageing resistance, strength, chemical resistance and the like of the material.

The nano barium sulfate and/or nano silicon dioxide are respectively filled and compounded with the fully biodegradable copolyester as functional fillers, and the nano barium sulfate and the nano silicon dioxide have good optical properties and small size, so that the transparency of the fully biodegradable copolyester is not adversely affected by adding a certain amount of nano barium sulfate and nano silicon dioxide, the excellent biodegradability of the material is kept, the mechanical property of the material can be improved, the cost is reduced, and the nano barium sulfate and/or nano silicon dioxide has important significance in the field of biodegradable transparent polyester films.

The invention also adopts plasticizer to improve the full-biodegradable copolyester filled with inorganic nano-filler, in particular to the film processing performance and the film flexibility of the full-biodegradable copolyester, and the dioctyl sebacate, the tributyl citrate, the epoxidized soybean oil and the trioctyl phosphate are nontoxic plasticizers with good compatibility with the full-biodegradable copolyester and have good plasticizing effect.

The fully biodegradable copolyester and the fully biodegradable copolyester mixture are subjected to vacuum drying treatment before use, wherein the temperature of the vacuum drying treatment is 60-80 ℃, and the time is 8-24 hours;

the inorganic nano filler is subjected to vacuum drying treatment before use, the temperature of the vacuum drying treatment is 110-130 ℃, and the time is 6-12 hours;

the thickness of the high-light-transmittance fully-biodegradable copolyester film is 45-65 mu m, the tensile strength is 28-39.3 MPa, the elongation at break is 320-620%, and the light transmittance is 75-89%.

The molecular chain of the fully biodegradable copolyester prepared by the preparation method of the fully biodegradable copolyester mainly comprises A₁Chain segment, A₂Segment, B₁Segment, B₂The number average molecular weight is 2200-4700 g/mol, the hydroxyl value is 30.0-65.0 mgKOH/g, and the molar weight of the rigid monomer in a nuclear magnetic spectrum accounts for B₁、B₂And the sum of the molar amounts of the rigid monomers in a ratio to the moles of rigid monomers at the time of feedingMolar amount of B₁、B₂And the sum of the molar amounts of the rigid monomers is 0 to 4 percent lower.

The application of the fully biodegradable copolyester is to blow the fully biodegradable copolyester mixture mainly consisting of the fully biodegradable copolyester and the cross-linking agent as a raw material to form a film so as to prepare the plasticized fully biodegradable copolyester film;

the preparation process of the full-biodegradable copolyester mixture comprises the following steps: mixing and stirring the fully biodegradable copolyester with the weight portion ratio of 100: 5-15 and a cross-linking agent uniformly, and extruding and granulating;

the mixing and stirring temperature is 23-27 ℃, the rotating speed is 150-200 r/min, the time is 10min, and the extrusion granulation temperature is 150-180 ℃;

the cross-linking agent is hexamethylene diisocyanate, tributyl citrate or epoxidized soybean oil;

the thickness of the plasticized full-biodegradable copolyester film is 68-85 mu m, the tensile strength is 21-32 MPa, and the elongation at break is 300-600%.

Has the advantages that:

(1) the preparation method of the full-biodegradable copolyester can effectively reduce the side reactions such as thermal degradation and crosslinking of carbohydrate derived oxygen heterocyclic monomer IHDCA or IHDXC in the preparation process of the copolyester, and the molecular weight and the intrinsic viscosity of the prepared copolyester meet the application requirements;

(2) the fully biodegradable copolyester has low content of aromatic monomers and high biodegradability;

(3) the fully biodegradable copolyester fiber has good mechanical property and excellent hygroscopicity;

(4) the high-light-transmittance fully-biodegradable copolyester film can improve the optical property and mechanical property of a product and reduce the production cost;

(5) the plasticized full-biodegradable copolyester film disclosed by the invention is excellent in mechanical property, and the market competitiveness of the plasticized full-biodegradable copolyester film is further expanded.

Detailed Description

The invention will be further illustrated with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1

The preparation process of the full-biodegradable copolyester comprises the following steps:

(1) the first stage reaction: 1, 4-butanediol, terephthalic acid and adipic acid are taken as raw materials, phosphoric acid and an antioxidant 1010 are added simultaneously, esterification is carried out for 2h under the condition of 190 ℃ and the action of tetrabutyl titanate, and then prepolymerization is carried out for 0.5h under the conditions of 0.05mbar pressure and 200 ℃, wherein the ratio of the molar quantity of the 1, 4-butanediol to the sum of the molar quantities of the terephthalic acid and the adipic acid is 1.1:1, the ratio of the molar quantity of the tetrabutyl titanate to the sum of the molar quantities of the terephthalic acid and the adipic acid is 50ppm, and the addition amounts of the phosphoric acid and the antioxidant 1010 are respectively 0.1 percent and 0.2 percent of the sum of the masses of the 1, 4-butanediol, the terephthalic acid and the adipic acid;

(2) and (3) second-stage reaction: taking the first-stage product, IIDCA and 1, 4-butanediol as raw materials, simultaneously adding phosphoric acid and an antioxidant 1010, and esterifying for 2h under the action of dibutyltin oxide (catalyst) at the temperature of 130 ℃, wherein the molar ratio of the 1, 4-butanediol to the IIDCA is 2:1, the molar ratio of the dibutyltin oxide to the IIDCA is 68ppm, and the adding amounts of the phosphoric acid and the antioxidant 1010 are respectively 0.5 percent and 0.3 percent of the sum of the masses of the IIDCA and the 1, 4-butanediol;

the molar weight of the terephthalic acid in the step (1) is 15 percent of the sum of the molar weights of the terephthalic acid in the step (1), the adipic acid in the step (1) and the IIDCA in the step (2); the molar amount of IIDCA in the step (2) is 4% of the sum of the molar amounts of terephthalic acid in the step (1), adipic acid in the step (1) and IIDCA in the step (2);

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: prepolycondensation was carried out for 0.5h at 190 ℃ under 0.05mbar and for 2h at 150 ℃ under 0.05 mbar.

The final fully biodegradable copolyester had an intrinsic viscosity of 0.68dL/g and a number average molecular weight of 23,000g/mol, and the molar amount of IIDCA in a nuclear magnetic spectrum accounted for the sum of the molar amounts of terephthalic acid, adipic acid and IIDCA by 0% lower than the molar amount of IIDCA accounted for the sum of the molar amounts of terephthalic acid, adipic acid and IIDCA at the time of feeding.

Comparative example 1

A fully biodegradable copolyester was prepared substantially as in example 1 except that the catalyst for the second stage reaction was zinc acetate, the final fully biodegradable copolyester had an intrinsic viscosity of 0.50dL/g and a number average molecular weight of 1,7820g/mol, and the molar amount of IIDCA in a nuclear magnetic spectrum was 1% less than the molar amount of IIDCA in the feed of terephthalic acid, adipic acid and IIDCA.

Comparing example 1 with comparative example 1, it can be seen that the intrinsic viscosity of the fully biodegradable copolyester prepared in example 1 is higher, the number average molecular weight is larger, and the proportion of the molar amount of IIDCA to the sum of the molar amounts of terephthalic acid, adipic acid and IIDCA in the nuclear magnetic spectrum is reduced less than that of the molar amount of IIDCA to the sum of the molar amounts of terephthalic acid, adipic acid and IIDCA when feeding, because the catalyst for the second-stage reaction in example 1 is dibutyltin oxide, and the catalytic activity in the bulk system is better than that of zinc acetate, so the copolymerization effect is better.

Comparative example 2

A fully biodegradable copolyester was prepared substantially as in example 1 except that the temperature of the first stage reaction was 150 ℃ and the final fully biodegradable copolyester had an intrinsic viscosity of 0.30dL/g and a number average molecular weight of 12,000g/mol, and the molar amount of IIDCA in a nuclear magnetic spectrum was 2% less than the molar amount of IIDCA in the feed of terephthalic acid, adipic acid and IIDCA.

Comparing example 1 with comparative example 2, it can be seen that the intrinsic viscosity of the fully biodegradable copolyester prepared in example 1 is higher, the number average molecular weight is larger, and the proportion of the molar amount of IIDCA to the sum of the molar amounts of terephthalic acid, adipic acid and IIDCA in the nuclear magnetic spectrum is reduced less than the proportion of the molar amount of IIDCA to the sum of the molar amounts of terephthalic acid, adipic acid and IIDCA in the feeding, because the copolymerization effect is better because the temperature of the first stage reaction is higher and the esterification degree is more complete in example 1.

Comparative example 3

A fully biodegradable copolyester is prepared in the same manner as in example 1, except that the temperature in the second stage is 200 deg.C, and the final product is a gel which is difficult to dissolve in organic solvents (such as hexafluoroisopropanol, trifluoroacetic acid, chloroform, tetrahydrofuran, etc.).

Comparing example 1 with comparative example 3, it can be seen that example 1 can prepare fully biodegradable copolyester with higher intrinsic viscosity and number average molecular weight and no gel formation because the temperature of the second stage reaction in example 1 is lower than the temperature of IIDMC at which thermal degradation side reaction (e.g., ring opening side reaction) occurs, thereby effectively maintaining the hydroxyl to carboxyl ratio and avoiding further crosslinking reaction and gel formation.

Example 2

(1) the first stage reaction: taking 1, 4-butanediol, terephthalic acid and suberic acid as raw materials, simultaneously adding phosphoric acid and an antioxidant 1010, esterifying for 2h under the action of tetrabutyl titanate at the temperature of 190 ℃, and then pre-polymerizing for 0.5h under the conditions of 100mbar pressure and 200 ℃, wherein the ratio of the molar weight of the 1, 4-butanediol to the sum of the molar weights of the terephthalic acid and the suberic acid is 1.1:1, the ratio of the molar weight of the tetrabutyl titanate to the sum of the molar weights of the terephthalic acid and the suberic acid is 50ppm, and the adding amounts of the phosphoric acid and the antioxidant 1010 are respectively 0.1 percent and 0.2 percent of the sum of the masses of the 1, 4-butanediol, the terephthalic acid and the suberic acid;

(2) and (3) second-stage reaction: taking the first-stage product, IMDCA and 1, 4-butanediol as raw materials, simultaneously adding phosphoric acid and an antioxidant 1010, and esterifying for 2h under the action of dibutyltin oxide at the temperature of 140 ℃, wherein the molar ratio of the 1, 4-butanediol to the IMDCA is 2:1, the molar ratio of the dibutyltin oxide to the IMDCA is 68ppm, and the adding amounts of the phosphoric acid and the antioxidant 1010 are respectively 0.5 percent and 0.3 percent of the sum of the masses of the IMDCA and the 1, 4-butanediol;

the molar weight of the terephthalic acid in the step (1) is 20% of the sum of the molar weights of the terephthalic acid in the step (1), the suberic acid in the step (1) and the IMDCA in the step (2), and the molar weight of the IMDCA in the step (2) is 1% of the sum of the molar weights of the terephthalic acid in the step (1), the suberic acid in the step (1) and the IMDCA in the step (2);

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: prepolycondensation was carried out for 2h at 190 ℃ under 0.05mbar and for 4h at 160 ℃ under 0.5 mbar.

The final prepared fully biodegradable copolyester has the intrinsic viscosity of 0.60dL/g and the number average molecular weight of 20,800g/mol, and the proportion of the molar weight of IMDCA in a nuclear magnetic spectrum to the sum of the molar weights of terephthalic acid, suberic acid and IMDCA is 0 percent lower than the proportion of the molar weight of IMDCA to the sum of the molar weights of terephthalic acid, suberic acid and IMDCA in the feeding process.

Example 3

(1) the first stage reaction: taking 1, 3-propanediol, dimethyl isophthalate and dimethyl malonate as raw materials, simultaneously adding phosphorous acid (a heat stabilizer) and an antioxidant 1076, esterifying for 2.5h under the condition of 215 ℃ and the action of tetraisopropyl titanate, and then pre-polymerizing for 1h under the conditions of 0.7mbar pressure and 220 ℃ wherein the ratio of the molar quantity of the 1, 3-propanediol to the sum of the molar quantities of the dimethyl isophthalate and the dimethyl malonate is 1.2:1, the ratio of the molar quantity of the tetraisopropyl titanate to the sum of the molar quantities of the dimethyl isophthalate and the dimethyl malonate is 250ppm, and the adding amounts of the phosphorous acid and the antioxidant 1076 are respectively 0.3 percent and 0.1 percent of the sum of the masses of the 1, 3-propanediol, the dimethyl isophthalate and the dimethyl malonate;

(2) and (3) second-stage reaction: taking the first-stage product, IIDMC and ethylene glycol as raw materials, simultaneously adding phosphorous acid (a heat stabilizer) and an antioxidant 1425, and esterifying for 3 hours under the action of butylstannoic acid (a catalyst) at the temperature of 148 ℃, wherein the molar ratio of the ethylene glycol to the IIDMC is 1.8:1, the molar ratio of the butylstannoic acid to the IIDMC is 180ppm, and the adding amounts of the phosphorous acid and the antioxidant 1425 are respectively 0.1 percent and 0.2 percent of the sum of the masses of the IIDMC and the ethylene glycol;

the molar quantity of the dimethyl isophthalate in the step (1) is 5 percent of the sum of the molar quantities of the dimethyl isophthalate in the step (1), the dimethyl malonate in the step (1) and the IIDMC in the step (2), and the molar quantity of the IIDMC in the step (2) is 18 percent of the sum of the molar quantities of the dimethyl isophthalate in the step (1), the dimethyl malonate in the step (1) and the IIDMC in the step (2);

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: prepolycondensation was carried out for 1.5h under a pressure of 0.05mbar and a temperature of 250 ℃ and polycondensation was carried out for 5h under a pressure of 0.1mbar and a temperature of 165 ℃.

The final fully biodegradable copolyester had an intrinsic viscosity of 0.65dL/g and a number average molecular weight of 21,900g/mol, and the proportion of the molar amount of IIDMC in the nuclear magnetic spectrum based on the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC was 3% lower than the proportion of the molar amount of IIDMC in the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC at the time of feeding.

Example 4

A fully biodegradable copolyester was prepared substantially as in example 3 except that no heat stabilizer or antioxidant was added in the first and second reaction stages, the resulting fully biodegradable copolyester had an intrinsic viscosity of 0.55dL/g and a number average molecular weight of 19,000g/mol, and the ratio of the molar amount of IIDMC in the nuclear magnetic spectrum to the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC was 3% lower than the ratio of the molar amount of IIDMC in the course of addition to the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC.

Example 5

A fully biodegradable copolyester was prepared substantially as in example 3, except that the first-stage reaction did not include a prepolymerization process and the first-stage reaction was esterified for 3.5 hours, the resulting fully biodegradable copolyester had an intrinsic viscosity of 0.51dL/g and a number average molecular weight of 18,000g/mol, and the molar amount of IIDMC in the NMR spectrum was 4% less than the ratio of the molar amount of IIDMC to the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC at the time of feeding.

Example 6

A fully biodegradable copolyester was prepared substantially as in example 3, except that the catalyst for the second stage reaction was a mixture of dibutyltin oxide and stannous octoate in a mass ratio of 1:1, the intrinsic viscosity of the finally obtained fully biodegradable copolyester was 0.71dL/g, the number average molecular weight was 23,500g/mol, and the ratio of the molar amount of IIDMC to the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC in the nuclear magnetic spectrum was 2% lower than that in the case of charging.

Example 7

(1) the first stage reaction: taking 1, 3-propylene glycol and succinic acid as raw materials, simultaneously adding hypophosphorous acid and a mixture of an antioxidant 1010 and an antioxidant 1076 with a mass ratio of 1:1, esterifying for 5 hours under the action of tetrabutyl titanate at the temperature of 200 ℃, and then pre-polymerizing for 2 hours under the conditions of 55mbar pressure and 260 ℃, wherein the molar ratio of the 1, 3-propylene glycol to the succinic acid is 1.01:1, the molar ratio of the tetrabutyl titanate to the succinic acid is 1200ppm, the addition amount of the hypophosphorous acid is 2 percent of the sum of the masses of the 1, 3-propylene glycol and the succinic acid, and the addition amount of the mixture of the antioxidant 1010 and the antioxidant 1076 is 1.7 percent of the sum of the masses of the 1, 3-propylene glycol and the succinic acid;

(2) and (3) second-stage reaction: taking the first-stage product, ISDCA and 1, 2-butanediol as raw materials, simultaneously adding hypophosphorous acid and a mixture of antioxidant 1010, antioxidant 1076 and antioxidant 1425 in a mass ratio of 1:1:1, esterifying for 5 hours at the temperature of 170 ℃ under the action of a mixture of dibutyltin oxide and stannous octoate with the mass ratio of 1:1, wherein the molar weight of the ISDCA is 48% of the sum of the ISDCA and the molar weight of the succinic acid in the step (1), the molar ratio of 1, 2-butanediol to the ISDCA is 1.6:1, the molar ratio of a mixture of dibutyltin oxide and stannous octoate to the ISDCA is 2000ppm, the addition amount of the hypophosphorous acid is 1.2% of the sum of the mass of the ISDCA and the mass of the 1, 2-butanediol, and the addition amount of a mixture of an antioxidant 1010, an antioxidant 1076 and an antioxidant 1425 is 2% of the sum of the mass of the ISDCA and the mass of the 1, 2-butanediol;

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: prepolycondensation was carried out for 2h at a pressure of 100mbar and a temperature of 260 ℃ and final polycondensation was carried out for 5h at a pressure of 1mbar and a temperature of 180 ℃.

The final prepared fully biodegradable copolyester has the intrinsic viscosity of 1.0dL/g and the number average molecular weight of 30,000g/mol, and the proportion of the molar weight of the ISDCA in a nuclear magnetic spectrum to the molar weight of the succinic acid and the ISDCA is lower than that of the molar weight of the ISDCA in the feeding process by 4 percent.

Example 8

(1) the first stage reaction: taking 1, 2-butanediol, isophthalic acid and glutaric acid as raw materials, simultaneously adding pyrophosphoric acid (a heat stabilizer) and an antioxidant 1010, esterifying for 3.5h under the condition of 260 ℃ and the action of zinc acetate (a catalyst), and then pre-polymerizing for 1h under the conditions of 30mbar pressure and 230 ℃, wherein the ratio of the molar quantity of the 1, 2-butanediol to the sum of the molar quantities of the isophthalic acid and the glutaric acid is 1.5:1, the ratio of the molar quantity of the zinc acetate to the sum of the molar quantities of the isophthalic acid and the glutaric acid is 2000ppm, and the adding amounts of the pyrophosphoric acid and the antioxidant 1010 are respectively 0.4 and 0.6 percent of the sum of the masses of the 1, 2-butanediol, the isophthalic acid and the glutaric acid;

(2) and (3) second-stage reaction: taking the first-stage product, IIDCA and 1, 2-propylene glycol as raw materials, simultaneously adding ammonium phosphate (a heat stabilizer) and an antioxidant 1076, and esterifying for 4 hours under the action of stannous 2-ethyl hexanoate (a catalyst) at the temperature of 150 ℃, wherein the molar ratio of 1, 2-propylene glycol to IIDCA is 1.01:1, the molar ratio of stannous 2-ethyl hexanoate to IIDCA is 1000ppm, and the adding amounts of the ammonium phosphate and the antioxidant 1076 are respectively 0.6 percent and 0.8 percent of the sum of the masses of IIDCA and 1, 2-propylene glycol;

the molar quantity of the isophthalic acid in the step (1) is 12 percent of the sum of the molar quantities of the isophthalic acid in the step (1), the glutaric acid in the step (1) and the IIDCA in the step (2), and the molar quantity of the IIDCA in the step (2) is 48 percent of the sum of the molar quantities of the isophthalic acid in the step (1), the glutaric acid in the step (1) and the IIDCA in the step (2);

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: prepolycondensation was carried out at 50mbar pressure and 230 ℃ for 2h and then final polycondensation was carried out at 1mbar pressure and 165 ℃ for 4 h.

The final fully biodegradable copolyester had an intrinsic viscosity of 0.78dL/g and a number average molecular weight of 25,700g/mol, and the molar amount of IIDCA in a nuclear magnetic spectrum was 1% lower than the molar amount of IIDCA in the total molar amount of isophthalic acid, glutaric acid and IIDCA at the time of feeding.

Example 9

A fully biodegradable copolyester was prepared substantially as in example 8, except that the reaction raw material IIDCA in step (2) was replaced with methyl isosorbide-2, 5-dicarboxylate, and the finally obtained fully biodegradable copolyester had an intrinsic viscosity of 0.77dL/g and a number average molecular weight of 25,100g/mol, and the ratio of the molar amount of methyl isosorbide-2, 5-dicarboxylate to the sum of the molar amounts of isophthalic acid, glutaric acid and methyl isosorbide-2, 5-dicarboxylate in a nuclear magnetic spectrum was 2% lower than that of the sum of the molar amounts of isophthalic acid, glutaric acid and methyl isosorbide-2, 5-dicarboxylate in the case of feeding.

Example 10

A fully biodegradable copolyester was prepared in substantially the same manner as in example 8, except that the reaction material IIDCA in step (2) was replaced with isomannide-2,5-dicarboxylic acid methyl ester, and the finally obtained fully biodegradable copolyester had an intrinsic viscosity of 0.65dL/g and a number average molecular weight of 19,850g/mol, and a ratio of the molar amount of isomannide-2,5-dicarboxylic acid methyl ester to the sum of the molar amounts of isophthalic acid, glutaric acid and isomannide-2,5-dicarboxylic acid methyl ester in a nuclear magnetic spectrum was 3% lower than that of isomannide-2,5-dicarboxylic acid methyl ester to the sum of the molar amounts of isophthalic acid, glutaric acid and isomannide-2,5-dicarboxylic acid methyl ester at the time of feeding.

Examples 11 to 24

A fully biodegradable copolyester, the preparation process is substantially the same as that of example 8, except that the raw materials, catalyst and heat stabilizer for the first stage reaction and the diol, catalyst and heat stabilizer for the second stage reaction are different in kind, which are specifically shown in table 1, and the properties of the finally prepared fully biodegradable copolyester are respectively shown in table 2.

TABLE 1

TABLE 2

Example 25

The fully biodegradable copolyester fiber is prepared by drying, melting by a spinning screw, extruding, spinning, cooling, winding and stretching the fully biodegradable copolyester prepared in the embodiment 1 in sequence, and the melt spinning processing technological parameters are as follows: the drying time of the fully biodegradable copolyester is 12 hours, the drying temperature is 80 ℃, the temperature of a spinning screw is 160 ℃, the spinning speed is 1000m/min, the cooling temperature is 24 ℃, the stretching temperature is 60 ℃, the pre-stretching multiplying power is 1.05, the primary stretching multiplying power is 2.7, and the secondary stretching multiplying power is 1.1; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 1.58dtex, the length is 38mm, the moisture regain is 3.3%, the surface contact angle is 67 degrees, the mechanical strength is 2.5cN/dtex, and the modulus is 60 cN/dtex.

Example 26

The preparation process of the fully biodegradable copolyester fiber includes the steps of drying, melting with spinning screw, extruding, spinning, cooling, winding and stretching the fully biodegradable copolyester fiber prepared in the embodiment 2 successively, and the melt spinning process has the specific technological parameters as follows: the drying time of the fully biodegradable copolyester is 20 hours, the drying temperature is 60 ℃, the temperature of a spinning screw is 150 ℃, the spinning speed is 500m/min, the cooling temperature is 18 ℃, the stretching temperature is 50 ℃, the pre-stretching ratio is 1, the primary stretching ratio is 2.5, and the secondary stretching ratio is 1.05; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 1dtex, the length is 38mm, the moisture regain is 3.0%, the surface contact angle is 70 degrees, the mechanical strength is 2.0cN/dtex, and the modulus is 50 cN/dtex.

Example 27

The preparation process of the fully biodegradable copolyester fiber comprises the steps of drying the fully biodegradable copolyester in example 3, melting by a spinning screw, extruding, spinning, cooling, winding and stretching to obtain the fully biodegradable copolyester staple fiber, wherein the specific technological parameters of the melt spinning processing are as follows: the drying time of the fully biodegradable copolyester is 15 hours, the drying temperature is 70 ℃, the temperature of a spinning screw is 155 ℃, the spinning speed is 800m/min, the cooling temperature is 25 ℃, the stretching temperature is 55 ℃, the pre-stretching multiplying power is 1.02, the primary stretching multiplying power is 2.6, and the secondary stretching multiplying power is 1.06; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 1.50dtex, the length is 38mm, the moisture regain is 3.5%, the surface contact angle is 63 degrees, the mechanical strength is 2.3cN/dtex, and the modulus is 56 cN/dtex.

Example 28

The fully biodegradable copolyester fiber is prepared by drying, melting by a spinning screw, extruding, spinning, cooling, winding and stretching the fully biodegradable copolyester prepared in the embodiment 4 in sequence, wherein the specific technological parameters of the melt spinning processing are as follows: the drying time of the fully biodegradable copolyester is 24 hours, the drying temperature is 40 ℃, the temperature of a spinning screw is 140 ℃, the spinning speed is 500m/min, the cooling temperature is 19 ℃, the stretching temperature is 50 ℃, the pre-stretching ratio is 1, the primary stretching ratio is 2.5, and the secondary stretching ratio is 1.05; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 1.0dtex, the length is 38mm, the moisture regain is 3.8%, the surface contact angle is 62 degrees, the mechanical strength is 2.2cN/dtex, and the modulus is 52 cN/dtex.

Example 29

The fully biodegradable copolyester fiber is prepared by drying, melting by a spinning screw, extruding, spinning, cooling, winding and stretching the fully biodegradable copolyester prepared in the embodiment 6 in sequence, wherein the specific technological parameters of the melt spinning processing are as follows: the drying time of the fully biodegradable copolyester is 12 hours, the drying temperature is 100 ℃, the temperature of a spinning screw is 165 ℃, the spinning speed is 1200m/min, the cooling temperature is 26 ℃, the stretching temperature is 65 ℃, the pre-stretching multiplying power is 1.07, the primary stretching multiplying power is 2.8, and the secondary stretching multiplying power is 1.12; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 2.18dtex, the length is 51mm, the moisture regain is 3.4%, the surface contact angle is 65 degrees, the mechanical strength is 2.9cN/dtex, and the modulus is 63 cN/dtex.

Example 30

The fully biodegradable copolyester fiber is prepared by drying, melting by a spinning screw, extruding, spinning, cooling, winding and stretching the fully biodegradable copolyester prepared in the embodiment 7 in sequence, wherein the specific process parameters of the melt spinning processing are as follows: the drying time of the fully biodegradable copolyester is 12 hours, the drying temperature is 120 ℃, the temperature of a spinning screw is 180 ℃, the spinning speed is 1600m/min, the cooling temperature is 23 ℃, the stretching temperature is 70 ℃, the pre-stretching multiplying power is 1.1, the primary stretching multiplying power is 3.0, and the secondary stretching multiplying power is 1.15; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 2.8dtex, the length is 51mm, the moisture regain is 4.8%, the surface contact angle is 46 degrees, the mechanical strength is 3.8cN/dtex, and the modulus is 70 cN/dtex.

Example 31

The fully biodegradable copolyester fiber is prepared by drying, melting by a spinning screw, extruding, spinning, cooling, winding and stretching the fully biodegradable copolyester prepared in the embodiment 8 in sequence, wherein the specific technological parameters of the melt spinning processing are as follows: the drying time of the fully biodegradable copolyester is 12 hours, the drying temperature is 110 ℃, the temperature of a spinning screw is 168 ℃, the spinning speed is 1300m/min, the cooling temperature is 22 ℃, the stretching temperature is 68 ℃, the pre-stretching multiplying power is 1.09, the primary stretching multiplying power is 2.9, and the secondary stretching multiplying power is 1.14; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 2.5dtex, the length is 51mm, the moisture regain is 4.0%, the surface contact angle is 58 degrees, the mechanical strength is 3.2cN/dtex, and the modulus is 66 cN/dtex.

Example 32

The fully biodegradable copolyester fiber is prepared by drying, melting by a spinning screw, extruding, spinning, cooling, winding and stretching the fully biodegradable copolyester prepared in the embodiment 9 in sequence, wherein the specific process parameters of the melt spinning processing are as follows: the drying time of the full-biodegradable copolyester is 10 hours, the drying temperature is 100 ℃, the temperature of a spinning screw is 170 ℃, the spinning speed is 1400m/min, the cooling temperature is 20 ℃, the stretching temperature is 70 ℃, the pre-stretching multiplying power is 1.09, the primary stretching multiplying power is 3.0, and the secondary stretching multiplying power is 1.15; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 2.7dtex, the length is 51mm, the moisture regain is 4.3%, the surface contact angle is 56 degrees, the mechanical strength is 3.3cN/dtex, and the modulus is 68 cN/dtex.

Example 33

The fully biodegradable copolyester fiber is prepared by drying, melting by a spinning screw, extruding, spinning, cooling and stretching after winding the fully biodegradable copolyester prepared in the embodiment 10, wherein the specific process parameters of the melt spinning processing are as follows: the drying time of the fully biodegradable copolyester is 12 hours, the drying temperature is 80 ℃, the temperature of a spinning screw is 145 ℃, the spinning speed is 900m/min, the cooling temperature is 25 ℃, the stretching temperature is 62 ℃, the pre-stretching multiplying power is 1.03, the primary stretching multiplying power is 2.6, and the secondary stretching multiplying power is 1.08; wherein the spinning screw is a double screw with degassing function, and the medium used for cooling is water; the titer of the prepared full-biodegradable copolyester staple fiber is 1.50dtex, the length is 38mm, the moisture regain is 4.5%, the surface contact angle is 53 degrees, the mechanical strength is 2.3cN/dtex, and the modulus is 57 cN/dtex.

Examples 34 to 47

The fully biodegradable copolyester fibers are prepared by drying, melting by a spinning screw, extruding, spinning, cooling and stretching after winding the fully biodegradable copolyester obtained in the embodiment 11-24, wherein the specific process parameters of the melt spinning process are basically the same as those of the embodiment 31, and the properties of the finally prepared fully biodegradable copolyester fibers are respectively shown in Table 3.

TABLE 3

Example 48

A high-light-transmittance fully-biodegradable copolyester film is prepared by the following steps:

(1) the fully biodegradable copolyester in the example 1 is subjected to vacuum drying treatment at 60 ℃ for 24 hours;

(2) mixing 100:10 parts by weight of fully biodegradable copolyester and tributyl citrate at normal temperature at the rotating speed of 150 rpm for 10 minutes, putting the mixture into a double-screw extruder, extruding and granulating the mixture at 130 ℃ to obtain a fully biodegradable copolyester mixture;

(3) carrying out vacuum drying treatment on the fully biodegradable copolyester mixture obtained in the step (2) at 60 ℃ for 24 hours, and then carrying out blow molding on the mixture serving as a raw material to form a film so as to obtain a high-light-transmittance fully biodegradable copolyester film; the thickness of the high-light-transmittance fully-biodegradable copolyester film is 55 mu m, the tensile strength is 32.1MPa, the elongation at break is 370 percent, and the light transmittance is 75 percent.

Example 49

A high-light-transmittance fully-biodegradable copolyester film is prepared by

(1) Carrying out vacuum drying treatment on the fully biodegradable copolyester in the embodiment 2 at 70 ℃ for 16 hours, and carrying out vacuum drying treatment on nano barium sulfate at 120 ℃ for 8 hours;

(2) mixing 100:20:15 parts by weight of fully biodegradable copolyester, tributyl citrate and nano barium sulfate at 23 ℃ and a rotating speed of 180 revolutions per minute for 10 minutes, putting into a double-screw extruder, extruding and granulating at 170 ℃ to obtain a fully biodegradable copolyester mixture;

(3) carrying out vacuum drying treatment on the fully biodegradable copolyester mixture obtained in the step (2) at 70 ℃ for 16 hours, and then carrying out blow molding on the mixture serving as a raw material to form a film so as to obtain a high-light-transmittance fully biodegradable copolyester film; the thickness of the high-light-transmittance fully-biodegradable copolyester film is 60 micrometers, the tensile strength is 35MPa, the elongation at break is 430%, and the light transmittance is 82%.

Example 50

(1) carrying out vacuum drying treatment on the fully biodegradable copolyester in the embodiment 3 at 80 ℃ for 8 hours, and carrying out vacuum drying treatment on nano silicon dioxide at 130 ℃ for 6 hours;

(2) mixing 100:25:20 parts by weight of fully biodegradable copolyester, dioctyl sebacate and nano silicon dioxide at 27 ℃ and a rotating speed of 200 rpm for 10 minutes, putting into a double-screw extruder, extruding and granulating at 180 ℃ to obtain a fully biodegradable copolyester mixture;

(3) drying the fully biodegradable copolyester mixture obtained in the step (2) at 80 ℃ for 8 hours in vacuum, and performing blow molding on the mixture serving as a raw material to form a film so as to obtain a high-light-transmittance fully biodegradable copolyester film; the thickness of the high-light-transmittance fully-biodegradable copolyester film is 58 mu m, the tensile strength is 34.2MPa, the elongation at break is 440%, and the light transmittance is 85%.

Example 51

A high light transmittance all-biodegradable copolyester film, its preparation process is basically the same as example 50, except that the all-biodegradable copolyester in example 4 is used to prepare the high light transmittance all-biodegradable copolyester film; the thickness of the prepared high-light-transmittance fully-biodegradable copolyester film is 51 mu m, the tensile strength is 31MPa, the elongation at break is 360 percent, and the light transmittance is 81 percent.

Example 52

A high light transmittance all-biodegradable copolyester film is prepared in the same manner as in example 50, except that the all-biodegradable copolyester in example 5 is used to prepare the high light transmittance all-biodegradable copolyester film; the thickness of the prepared high-light-transmittance fully-biodegradable copolyester film is 45 micrometers, the tensile strength is 28MPa, the elongation at break is 320%, and the light transmittance is 77%.

Example 53

A high light transmittance all-biodegradable copolyester film, the preparation process is substantially the same as that of example 50, except that the all-biodegradable copolyester of example 6 is used to prepare the high light transmittance all-biodegradable copolyester film; the thickness of the prepared high-light-transmittance fully-biodegradable copolyester film is 58 mu m, the tensile strength is 36.2MPa, the elongation at break is 500%, and the light transmittance is 87%.

Example 54

(1) vacuum drying the fully biodegradable copolyester in the example 7 at 80 ℃ for 8 hours, and vacuum drying the nano barium sulfate at 130 ℃ for 6 hours;

(2) mixing 100:20:10 parts by weight of fully biodegradable copolyester, epoxidized soybean oil and nano barium sulfate at 25 ℃ for 10 minutes at a rotating speed of 200 rpm, putting the mixture into a double-screw extruder, extruding and granulating the mixture at 180 ℃ to obtain a fully biodegradable copolyester mixture;

(3) drying the fully biodegradable copolyester mixture obtained in the step (2) at 80 ℃ for 8 hours in vacuum, and performing blow molding on the mixture serving as a raw material to form a film so as to obtain a high-light-transmittance fully biodegradable copolyester film; the thickness of the high-light-transmittance fully-biodegradable copolyester film is 65 mu m, the tensile strength is 39.3MPa, the elongation at break is 620%, and the light transmittance is 89%.

Example 55

(1) carrying out vacuum drying treatment on the fully biodegradable copolyester in the embodiment 8 at 80 ℃ for 8 hours, and carrying out vacuum drying treatment on nano barium sulfate at 110 ℃ for 12 hours;

(2) mixing 100:25:20 parts by weight of fully biodegradable copolyester, trioctyl phosphate and nano barium sulfate at 26 ℃ for 10 minutes at a rotating speed of 200 rpm, putting into a double-screw extruder, extruding and granulating at 180 ℃ to obtain a fully biodegradable copolyester mixture;

(3) drying the fully biodegradable copolyester mixture obtained in the step (2) at 80 ℃ for 8 hours in vacuum, and performing blow molding on the mixture serving as a raw material to form a film so as to obtain a high-light-transmittance fully biodegradable copolyester film; the thickness of the high-light-transmittance fully-biodegradable copolyester film is 60 micrometers, the tensile strength is 37MPa, the elongation at break is 540%, and the light transmittance is 86%.

Example 56

A high light transmittance all-biodegradable copolyester film, the preparation process is substantially the same as that of example 55, except that the all-biodegradable copolyester of example 9 is used to prepare the high light transmittance all-biodegradable copolyester film; the thickness of the prepared high-light-transmittance fully-biodegradable copolyester film is 60 mu m, the tensile strength is 36.3MPa, the elongation at break is 520%, and the light transmittance is 84%.

Example 57

A high light transmittance all-biodegradable copolyester film, the preparation process is substantially the same as that of example 55, except that the all-biodegradable copolyester of example 10 is used to prepare the high light transmittance all-biodegradable copolyester film; the thickness of the prepared high-light-transmittance fully-biodegradable copolyester film is 52 mu m, the tensile strength is 32MPa, the elongation at break is 400%, and the light transmittance is 81.3%.

Examples 58 to 71

The preparation process of the high-transmittance fully biodegradable copolyester film is basically the same as that in example 55, except that the fully biodegradable copolyester obtained in examples 11 to 24 is used for preparing the high-transmittance fully biodegradable copolyester film, and the properties of the finally prepared fully biodegradable copolyester and the high-transmittance fully biodegradable copolyester film are respectively shown in table 4.

TABLE 4

Example 72

A plasticizable, fully biodegradable copolyester film, which was prepared in the same manner as in example 1 in (1) and (2), except that:

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: and (3) reacting for 0.5h under the conditions of 0.05mbar pressure and 190 ℃ to obtain the fully biodegradable copolyester, wherein the number average molecular weight of the fully biodegradable copolyester is 3,600g/mol, the hydroxyl value is 39.2mgKOH/g, and the proportion of the molar weight of IIDCA in a nuclear magnetic spectrum to the sum of the molar weights of terephthalic acid, adipic acid and IIDCA is 0% lower than the proportion of the molar weight of IIDCA to the sum of the molar weights of terephthalic acid, adipic acid and IIDCA in the feeding process.

(4) Carrying out vacuum drying treatment on the fully biodegradable copolyester in the step (3) at 60 ℃ for 24 hours;

(5) mixing 100:10 parts by weight of fully biodegradable copolyester and epoxidized soybean oil at 26 ℃ for 10 minutes at a rotating speed of 150 revolutions per minute, putting the mixture into a double-screw extruder, extruding and granulating the mixture at 150 ℃ to obtain a fully biodegradable copolyester mixture;

(6) drying the fully biodegradable copolyester mixture obtained in the step (5) at 60 ℃ for 24 hours in vacuum, and performing blow molding on the mixture serving as a raw material to form a plasticized fully biodegradable copolyester film; the thickness of the plasticized full-biodegradable copolyester film is 75 micrometers, the tensile strength is 25MPa, and the elongation at break is 350%.

Example 73

A plasticizable, fully biodegradable copolyester film, which was prepared by the same procedures (1) and (2) as in example 2, except that:

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: reacting for 2 hours under the conditions of 0.05mbar pressure and 190 ℃; the number average molecular weight of the prepared fully biodegradable copolyester is 3,270g/mol, the hydroxyl value is 43.8mgKOH/g, and the proportion of the molar weight of IMDCA in a nuclear magnetic spectrum to the sum of the molar weights of terephthalic acid, suberic acid and IMDCA is 0 percent lower than the proportion of the molar weight of IMDCA to the sum of the molar weights of terephthalic acid, suberic acid and IMDCA in the feeding process.

(4) Carrying out vacuum drying treatment on the fully biodegradable copolyester in the step (3) at 70 ℃ for 16 hours;

(5) mixing 100:15 parts by weight of fully biodegradable copolyester and hexamethylene diisocyanate at 25 ℃ for 10 minutes at a rotating speed of 180 r/min, putting the mixture into a double-screw extruder, and extruding and granulating the mixture at 170 ℃ to obtain a fully biodegradable copolyester mixture;

(6) drying the fully biodegradable copolyester mixture obtained in the step (5) at 70 ℃ for 16 hours in vacuum, and performing blow molding on the mixture serving as a raw material to form a plasticized fully biodegradable copolyester film; the thickness of the plasticized full-biodegradable copolyester film is 79 microns, the tensile strength is 28MPa, and the elongation at break is 410%.

Example 74

A plasticizable, fully biodegradable copolyester film, which was prepared by the same procedures (1) and (2) as in example 3, except that:

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: reacting for 1.5h under the conditions of 0.05mbar pressure and 250 ℃; the number average molecular weight of the prepared fully biodegradable copolyester is 3,440g/mol, the hydroxyl value is 41.5mgKOH/g, and the proportion of the molar weight of IIDMC in the sum of the molar weights of dimethyl isophthalate, dimethyl malonate and IIDMC in a nuclear magnetic spectrum is 3 percent lower than that of the molar weight of IIDMC in the sum of the molar weights of dimethyl isophthalate, dimethyl malonate and IIDMC in the feeding process.

(4) Carrying out vacuum drying treatment on the fully biodegradable copolyester in the step (3) at 80 ℃ for 8 hours;

(5) mixing 100:15 parts by weight of fully biodegradable copolyester and epoxidized soybean oil at 27 ℃ for 10 minutes at a rotating speed of 200 rpm, putting the mixture into a double-screw extruder, extruding and granulating the mixture at 180 ℃ to obtain a fully biodegradable copolyester mixture;

(6) drying the fully biodegradable copolyester mixture obtained in the step (5) at 80 ℃ for 8 hours in vacuum, and performing blow molding on the mixture serving as a raw material to form a plasticized fully biodegradable copolyester film; the thickness of the plasticized full-biodegradable copolyester film is 73 micrometers, the tensile strength is 27.2MPa, and the elongation at break is 420%.

Example 75

A plasticizable, fully biodegradable copolyester film, prepared substantially as in example 71, except that neither the first nor second reaction stages were used with the addition of heat stabilizers and antioxidants, the fully biodegradable copolyester was prepared having a number average molecular weight of 2,980g/mol, a hydroxyl number of 47.8mgKOH/g, and a nuclear magnetic spectrum in which the molar amount of IIDMC calculated as the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC was 3% less than the molar amount of IIDMC calculated as the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC at the time of feeding; the thickness of the prepared plasticized full-biodegradable copolyester film is 70 mu m, the tensile strength is 24MPa, and the elongation at break is 330%.

Example 76

A plasticizable, fully biodegradable copolyester film, prepared substantially as in example 71, except that the first stage reaction did not include prepolymerization and the first stage reaction was esterified for 3.5 hours, the fully biodegradable copolyester was prepared having a number average molecular weight of 2,820g/mol, and the molar amount of IIDMC in the hydroxyl number 50.5mgKOH/g NMR spectrum was 4% less than the molar amount of IIDMC in the feed plus the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC; the thickness of the prepared plasticized full-biodegradable copolyester film is 68 mu m, the tensile strength is 21MPa, and the elongation at break is 300%.

Example 77

A plasticizable, fully biodegradable copolyester film was prepared essentially as in example 71, except that the second stage reaction catalyst was a mixture of dibutyltin oxide and stannous octoate in a mass ratio of 1:1, the fully biodegradable copolyester had a number average molecular weight of 3,680 and a hydroxyl value of 38.7mgKOH/g, and the ratio of the molar amount of IIDMC in the nuclear magnetic spectrum to the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC was 2% lower than the ratio of the molar amount of IIDMC to the sum of the molar amounts of dimethyl isophthalate, dimethyl malonate and IIDMC when charged; the thickness of the prepared plasticized full-biodegradable copolyester film is 76 mu m, the tensile strength is 29.2MPa, and the elongation at break is 480%.

Example 78

A plasticizable, fully biodegradable copolyester film, which was prepared by the same procedures (1) and (2) as in example 7, except that:

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: reacting for 2 hours under the conditions of 100mbar pressure and 260 ℃; the number average molecular weight of the prepared fully biodegradable copolyester is 4,700g/mol, the hydroxyl value is 30.0mgKOH/g, and the proportion of the molar weight of ISDCA in a nuclear magnetic spectrum to the molar weight of succinic acid and ISDCA is lower than that of ISDCA in the nuclear magnetic spectrum by 4 percent.

(5) mixing 100:5 parts by weight of fully biodegradable copolyester and tributyl citrate at 23 ℃ for 10 minutes at a rotating speed of 200 rpm, putting the mixture into a double-screw extruder, and extruding and granulating the mixture at 180 ℃ to obtain a fully biodegradable copolyester mixture;

(6) drying the fully biodegradable copolyester mixture obtained in the step (5) at 80 ℃ for 8 hours in vacuum, and performing blow molding on the mixture serving as a raw material to form a plasticized fully biodegradable copolyester film; the thickness of the plasticized full-biodegradable copolyester film is 85 micrometers, the tensile strength is 32MPa, and the elongation at break is 600%.

Example 79

A plasticizable, fully biodegradable copolyester film, which was prepared by the same procedures (1) and (2) as in example 8, except that:

(3) carrying out polycondensation to prepare the full-biodegradable copolyester: firstly, reacting for 2 hours under the conditions of 50mbar pressure and 230 ℃; the number average molecular weight of the prepared fully biodegradable copolyester is 4,038g/mol, the hydroxyl value is 35.4mgKOH/g, and the proportion of the molar weight of IIDCA in the nuclear magnetic spectrum to the sum of the molar weights of the isophthalic acid, the glutaric acid and the IIDCA is 1 percent lower than that of the molar weight of IIDCA in the feeding process.

(5) mixing 100:15 parts by weight of fully biodegradable copolyester and epoxidized soybean oil at 26 ℃ for 10 minutes at a rotating speed of 200 rpm, putting the mixture into a double-screw extruder, extruding and granulating the mixture at 180 ℃ to obtain a fully biodegradable copolyester mixture;

(6) drying the fully biodegradable copolyester mixture obtained in the step (5) at 80 ℃ for 8 hours in vacuum, and performing blow molding on the mixture serving as a raw material to form a plasticized fully biodegradable copolyester film; the thickness of the plasticized full-biodegradable copolyester film is 84 microns, the tensile strength is 30MPa, and the elongation at break is 520%.

Example 80

A plasticized fully biodegradable copolyester film, which was prepared substantially as in example 79 except that the reaction raw material IIDCA in step (2) was replaced with methyl isosorbide-2, 5-dicarboxylate to give a fully biodegradable copolyester having a number average molecular weight of 3,944g/mol and a hydroxyl value of 36.3mgKOH/g, and the ratio of the molar amount of methyl isosorbide-2, 5-dicarboxylate to the sum of the molar amounts of isophthalic acid, glutaric acid and methyl isosorbide-2, 5-dicarboxylate in a nuclear magnetic spectrum was 2% lower than the ratio of the molar amount of methyl isosorbide-2, 5-dicarboxylate to the sum of the molar amounts of isophthalic acid, glutaric acid and methyl isosorbide-2, 5-dicarboxylate upon charging; the thickness of the prepared plasticized full-biodegradable copolyester film is 83 mu m, the tensile strength is 29MPa, and the elongation at break is 500%.

Example 81

A plasticized fully biodegradable copolyester film, which was prepared substantially as in example 79, except that the reaction raw material IIDCA in step (2) was replaced with methyl isomannide-2, 5-dicarboxylate to give a fully biodegradable copolyester having a number average molecular weight of 3,120g/mol and a hydroxyl value of 45.8mgKOH/g, and the ratio of the molar amount of methyl isomannide-2, 5-dicarboxylate to the sum of the molar amounts of isophthalic acid, glutaric acid and methyl isomannide-2, 5-dicarboxylate in the nuclear magnetic spectrum was 3% lower than the ratio of the molar amount of methyl isomannide-2, 5-dicarboxylate to the sum of the molar amounts of isophthalic acid, glutaric acid and methyl isomannide-2, 5-dicarboxylate upon charging; the thickness of the prepared plasticized full-biodegradable copolyester film is 72 mu m, the tensile strength is 25MPa, and the elongation at break is 380%.

Examples 82 to 95

The preparation process of a plasticized fully biodegradable copolyester film is substantially the same as that in example 79, except that the first stage and the second stage are the same as those in examples 11 to 24, specifically, as shown in table 5 below, and the properties of the finally prepared fully biodegradable copolyester are respectively shown in table 6.

TABLE 5

Example number	First stage	Second stage
			82	Same as example 11	Same as example 11
83	Same as example 12	Same as example 12
			84	Same as example 13	Same as example 13
85	Same as example 14	Same as example 14
			86	Same as example 15	Same as example 15
87	Same as example 16	Same as example 16
			88	Same as example 17	Same as example 17
89	Same as example 18	Same as example 18
			90	Same as example 19	Same as example 19
91	Same as example 20	Same as example 20
			92	Same as example 21	Same as example 21
93	Same as example 22	Same as example 22
			94	Same as example 23	Same as example 23
95	Same as example 24	Same as example 24

TABLE 6

Claims

1. A preparation method of full-biodegradable copolyester is characterized by comprising the following steps: firstly, with A₁、B₁And B₂The raw materials are subjected to a first-stage reaction under the action of a first catalyst under the condition of high temperature, and then a first-stage product, a rigid monomer and A are used₂The raw materials are subjected to a second-stage reaction under the low-temperature condition and the action of a second catalyst, and finally, a polycondensation reaction is carried out to prepare the fully biodegradable copolyester;

A₁and A₂Is a fatty diol, the two being the same or different, B₁Is an aromatic dicarboxylic acid and/or an alkyl ester thereof, added in an amount of 0 or other than 0, B₂The second catalyst is more than one of dibutyltin oxide, butylstannic acid, stannous octoate, 2-ethyl stannous hexanoate and tetrabutyl titanate; the high temperature is more than or equal to 190 ℃, and the low temperature is less than the temperature of the rigid monomer when the rigid monomer starts to generate thermal degradation side reaction;

the rigid monomer is more than one of isoidide-2,5-dicarboxylic acid, isomannide-2,5-dicarboxylic acid and isosorbide-2,5-dicarboxylic acid; alternatively, the rigid monomer is at least one of a methyl ester derivative of isoidide-2,5-dicarboxylic acid, a methyl ester derivative of isomannide-2,5-dicarboxylic acid, and a methyl ester derivative of isosorbide-2,5-dicarboxylic acid.

2. The method for preparing fully biodegradable copolyester according to claim 1, wherein A is₁Or A₂Is more than one of ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 2-butylene glycol, 1, 3-butylene glycol, 1, 4-butylene glycol, 2, 3-butylene glycol, 1, 5-pentanediol, 1, 4-pentanediol, 2, 4-pentanediol, 1, 6-hexanediol, 1, 5-hexanediol, 1, 4-hexanediol, 2, 5-hexanediol and 3, 4-hexanediol;

B₁is more than one of terephthalic acid, phthalic acid, isophthalic acid, 1, 8-naphthalene dicarboxylic acid, 2, 6-naphthalene dicarboxylic acid, furan-2, 5-dicarboxylic acid, furan-2, 4-dicarboxylic acid and furan-3, 4-dicarboxylic acid;

the first catalyst is a titanium catalyst, an antimony catalyst or a metal acetate; the second catalyst is a mixture of dibutyltin oxide and stannous octoate;

A₁molar amount of (A) and (B)₁And B₂The ratio of the sum of the molar amounts of (B) is 1.1 to 1.5:1, B₁In a molar amount of B₁、B₂And 0 to 20% of the sum of the molar amounts of the rigid monomers A₂The molar ratio of the first catalyst to the rigid monomer is 1.01-2.0: 1, and the molar amount of the first catalyst to B₁And B₂The ratio of the sum of the molar amounts of the first catalyst and the second catalyst is 50 to 2000ppm, and the molar ratio of the second catalyst to the rigid monomer is 50 to 2000 ppm;

the temperature of the first stage reaction is 190-260 ℃, and the time is 2-5 h; the temperature of the second stage reaction is 130-170 ℃, and the time is 2-5 h.

3. The method for preparing fully biodegradable copolyester according to claim 2, wherein the first stage reaction further comprises a prepolymerization reaction after esterification or transesterification, the prepolymerization reaction is carried out at 200-260 ℃ for 0.5-2 h and under 0.05-100 mbar.

4. The method for preparing fully biodegradable copolyester according to claim 2 or 3, wherein the polycondensation reaction comprises a pre-polycondensation process and a final polycondensation process, the temperature of the pre-polycondensation process is 190-260 ℃, the time is 0.5-2 h, the pressure is 0.05-100 mbar, the temperature of the final polycondensation process is 150-180 ℃, the time is 2-5 h, and the pressure is 0.05-1 mbar.

5. The method for preparing fully biodegradable copolyester according to claim 2 or 3, wherein the polycondensation reaction temperature is 190-260 ℃, the time is 0.5-2 h, and the pressure is 0.05-100 mbar.

6. The fully biodegradable copolyester obtained by the method for preparing the fully biodegradable copolyester according to claim 4, which is characterized in that: molecular chain mainly composed of A₁Chain segment, A₂Segment, B₁Segment, B₂The chain segment and the rigid monomer chain segment are combined, the intrinsic viscosity is 0.51-1.0 dL/g, the number average molecular weight is 18,000-30,000 g/mol, and the molar weight of the rigid monomer in a nuclear magnetic spectrum accounts for B₁、B₂And the sum of the molar amounts of the rigid monomers in a proportion such that the molar amount of the rigid monomer in the feed is B₁、B₂And the sum of the molar amounts of the rigid monomers is 0 to 4 percent lower.

7. The use of the fully biodegradable copolyester according to claim 6, wherein: preparing fully biodegradable copolyester fiber by melt spinning of fully biodegradable copolyester;

the spinning screw is a double screw with a degassing function, and the medium used for cooling is water;

the fully biodegradable copolyester fiber is short fiber, the titer is 1-3 dtex, and the length is 38mm or 51 mm; the moisture regain of the fully biodegradable copolyester fiber is more than or equal to 3.0 percent, the surface contact angle is less than or equal to 70 degrees, the mechanical strength is more than or equal to 2.0cN/dtex, and the elastic modulus is less than or equal to 70 cN/dtex.

8. The use of the fully biodegradable copolyester according to claim 6, wherein: blowing a fully biodegradable copolyester mixture mainly consisting of fully biodegradable copolyester, a plasticizer and an inorganic nano filler as a master batch to form a film so as to prepare a high-light-transmittance fully biodegradable copolyester film;

9. The fully biodegradable copolyester obtained by the method for preparing the fully biodegradable copolyester according to claim 5, wherein the method comprises the following steps: molecular chain mainly composed of A₁Chain segment, A₂Segment, B₁Segment, B₂The number average molecular weight is 2200-4700 g/mol, the hydroxyl value is 30.0-65.0 mgKOH/g, and the molar weight of the rigid monomer in a nuclear magnetic spectrum accounts for B₁、B₂And the sum of the molar amounts of the rigid monomers in a proportion such that the molar amount of the rigid monomer in the feed is B₁、B₂And the sum of the molar amounts of the rigid monomers is 0 to 4 percent lower.

10. Use of the fully biodegradable copolyester according to claim 9, characterized in that: the full-biodegradable copolyester mixture mainly composed of full-biodegradable copolyester and a cross-linking agent is used as a raw material to be blown into a film to prepare the plasticized full-biodegradable copolyester film;