CN110903469B - Low-crystallinity biodegradable polyester and preparation method thereof - Google Patents
Low-crystallinity biodegradable polyester and preparation method thereof Download PDFInfo
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- CN110903469B CN110903469B CN201911191410.8A CN201911191410A CN110903469B CN 110903469 B CN110903469 B CN 110903469B CN 201911191410 A CN201911191410 A CN 201911191410A CN 110903469 B CN110903469 B CN 110903469B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/66—Polyesters containing oxygen in the form of ether groups
- C08G63/668—Polyesters containing oxygen in the form of ether groups derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/676—Polyesters containing oxygen in the form of ether groups derived from polycarboxylic acids and polyhydroxy compounds in which at least one of the two components contains aliphatic unsaturation
Abstract
The invention relates to a low-crystallinity biodegradable polyester and a preparation method thereof, wherein the preparation method comprises the following steps: a, B and isosorbide are taken as main raw materials to prepare low-crystallinity biodegradable polyester through esterification or ester exchange reaction, pre-polycondensation reaction and final polycondensation reaction in sequence, wherein A is furan dicarboxylic acid or alkyl ester thereof, and B is aliphatic diol; the molecular chain of the finally prepared low-crystallinity biodegradable polyester mainly comprises an A chain segment, a B chain segment and an isosorbide chain segment, and the melting enthalpy of the low-crystallinity biodegradable polyester is less than 10J/g. The preparation method of the low-crystallization biodegradable polyester can effectively reduce the content of thermal degradation byproducts generated in the high-temperature polymerization process of the copolyester, reduce the yellowing of the product and avoid the interference of the product on the light transmittance when preparing a subsequent film product; the biodegradable polyester prepared by the method has low crystallinity, good biodegradability and low overall carbon footprint.
Description
Technical Field
The invention belongs to the technical field of high polymer materials, and relates to low-crystallinity biodegradable polyester and a preparation method thereof.
Background
Polymers have been one of the most important sources of materials for modern human society through a century of vigorous development. In a plurality of polymer application fields, the film polymer material is developed rapidly and is widely applied to a plurality of fields such as packaging materials, supermarket shopping bags, plant protection, agricultural production, electronic screen display films and the like. At present, the plastic films used for packaging materials, supermarket shopping bags, plant protection and the like mostly mainly comprise polyolefin polymers, the degradation period is long, and the use amount is huge, so that huge environmental pollution is brought to the ground surface, rivers, lakes and oceans. Meanwhile, the demand of film materials for electronic screen display has been rapidly increasing year by year, and is mainly closely related to the global high consumption of intelligent electronic products (such as smart phones and tablet computers). Optical functional films, such as a brightness enhancement film, a diffusion film, a conductive film, and a reflective film, which are based on biaxially oriented polyethylene terephthalate (BOPET), polypropylene (PP), Polycarbonate (PC), and the like, are used in a large number of liquid crystal display modules of these smart devices.
The optical properties of the film directly determine the quality of the relevant optically functional film. Haze and light transmission are generally the two most important properties that measure the optical quality of a film: light transmittance, which represents the ability of light to transmit through a medium, refers to the percentage of the luminous flux transmitted through a test object as compared to its incident luminous flux; and the haze refers to the percentage of the total transmitted light flux of the light flux with the transmitted light deviating from the incident direction by more than 2.5 degrees, and the higher the haze is, the higher the interference of the internal crystallization part of the material on the light transmission is. For example, when the film is applied to the fields of agricultural mulching and plant protection, the high light transmittance of the film is beneficial to the efficient penetration of sunlight, so that the photosynthesis efficiency of plants is improved, and the crop yield is increased; when the film is applied to the field of electronic products, the optical performance of the film has an important influence on the definition, brightness, color and other properties of a liquid crystal display (since polyethylene terephthalate (PET) belongs to semi-crystalline polyester, the haze of the film is increased due to the fact that the crystalline region in the polymer aggregation state interferes with the transmission of light, and in addition, additives such as a catalyst and an antioxidant added in the preparation process can also have negative influence on the haze value, so that the definition of a display screen is influenced).
The wide application of the traditional film materials benefits from better comprehensive properties such as mechanical, thermal and optical properties. However, at present, most of the polymer materials are highly dependent on the traditional petrochemical energy, not only consuming a large amount of non-renewable resources such as petroleum, but also causing high carbon emission and severe greenhouse effect. Meanwhile, numerous polymer varieties have caused great environmental pressure due to the difficulty in degradation in natural environments, and micro-plastics generated by physical disintegration thereof are seriously polluting the safety of soil, rivers, oceans and the whole food chain. Thus, the development of biodegradable polymers is one of the important approaches to solve the above problems. From the evaluation of the full life cycle of the material, the method utilizes renewable resources, particularly biomass resources, to prepare functional materials and realize the cyclic regeneration or biodegradation of the functional materials after the functional materials are discarded, and is an important development direction of future environment-friendly materials.
Due to the hydrolyzability and the microbial erodibility of ester bonds, the currently known biodegradable polymers are mainly polyester macromolecules, including polylactic acid (PLA), Polycaprolactone (PCL), polybutylene succinate (PBS), polyhydroxybutyrate, and the like. The chemical structure of the polymer mostly contains aliphatic alkane fragments with flexible structure and high flexibility, and compared with polyolefin or aromatic polyester, the thermal property and the mechanical strength of the polymer are in lower levels, so that a single polymer is difficult to use as a film material, and the comprehensive performance of the film is improved by introducing relatively rigid monomer or polymer units in the structure by using methods such as blending modification, copolymerization modification, plasticizing modification, composite modification and the like. Meanwhile, the biodegradable polyester has the chemical structure characteristic of high-content flexible fragments, so that the biodegradable polyester generally has high crystallinity, and when the biodegradable polyester is applied to some application fields requiring high light transmittance, a modifier such as a polyfunctional compound is additionally added to realize partial crosslinking so as to reduce the crystallinity of the biodegradable polyester and increase the light transmittance, but the generation of crosslinking can greatly improve the viscosity of a polymer, so that certain difficulty is brought to processing.
Carbohydrates (carbohydrates) are one of the most abundant natural biomass resources stored on the earth at present, and become a well-recognized novel future energy and chemical resource with high potential application value. By chemical or biological methods, the carbohydrate polysaccharide molecules can be depolymerized and converted to small molecules with lower functionality. Small molecule monomers that have received much attention at present include succinic acid, suberic acid, isohexides (isohexides), and furan-2, 5-dicarboxylic acid. In the prior art, a PET copolyester optical film with higher light transmittance and lower haze is prepared by copolymerizing isomannide, namely isomannide, with isophthalic acid, ethylene glycol and terephthalic acid, which is one of isomers in an isohexide family (synthesis and performance characterization of optical copolyester based on isomannide and isophthalic acid, organic chemistry, 2017,37, 3229-3235), however, the polymer system still mainly uses petroleum-based monomers (terephthalic acid and isophthalic acid), and the mass ratio of the bio-based monomer isomannide is only 1%. The high light transmittance of the copolyester system is realized mainly by adding petroleum-based monomer terephthalic acid and inhibiting the crystallinity and crystallization rate of the copolyester, and the polymer segment formed by bio-based monomer isomannide and terephthalic acid still has high crystallinity, so the effect of adding isomannide on the optical performance of the copolyester is not obvious, and meanwhile, the light transmittance of the polyester film is in a descending trend along with the increase of the addition amount of isophthalic acid, and the polyester film is mainly bright to the enhancement of the blue-violet light absorption capacity of the polyester film in a 330-550 nm region.
Therefore, the development of film material products with better optical performance (high transmittance and low haze) by utilizing bio-based raw materials has important significance.
Disclosure of Invention
The invention aims to solve the problem that the realization of low crystallinity of the biodegradable polyester in the prior art mainly depends on petroleum-based monomers, and aims to solve the problem that the prepared biodegradable polyester film has low light transmittance and high haze because a thermal degradation side reaction is generated during the copolymerization of the bio-based monomers in the prior art and a yellowing product of thermal degradation can absorb light with partial wavelength, thereby reducing the transmittance of the polyester and further causing the problems of low light transmittance and high haze of the prepared biodegradable polyester film, and provides the low-crystallinity biodegradable polyester and the preparation method thereof.
In order to achieve the purpose, the invention adopts the following scheme:
a method for preparing low-crystallinity biodegradable polyester takes A, B and isosorbide as main raw materials and then carries out esterification or ester exchange reaction, pre-polycondensation reaction and final polycondensation reaction to prepare the low-crystallinity biodegradable polyester, wherein A is furan dicarboxylic acid or alkyl ester thereof (A can be furan dicarboxylic acid or furan dicarboxylic acid alkyl ester, or can be a mixture of the furan dicarboxylic acid and the furan dicarboxylic acid alkyl ester), and B is aliphatic diol.
In the prior art, the crystallinity of polyester is reduced mainly by adding two monomers of isophthalic acid (6-8%) and isomannide (1-2%), wherein the aim of reducing the crystallinity is achieved by relying on the asymmetric structure of petroleum-based monomer isophthalic acid; the method for reducing the crystallinity is mainly realized by two bio-based monomers with highly asymmetric structures, namely furan dicarboxylic acid or alkyl ester thereof and isosorbide. The angle between the two carboxyl functions of furandicarboxylic acid is about 135 deg. different from the angle between the two carboxyl functions of terephthalic acid in chemical structure, while the dioxyheterocyclic structure of isosorbide is not a planar structure but a spatial angle of about 120 deg., and the two hydroxyl functions are in spatial stereo conformations of endo-and exo-, respectively. The macromolecular structure mainly composed of furan dicarboxylic acid or alkyl ester thereof and isosorbide has a highly distorted form in space, and thus crystallinity can be efficiently suppressed. According to different types of monomers, the content of the bio-based can reach 60-100%, and meanwhile, the invention can realize wide-range regulation and control of the glass transition temperature of the copolyester by adding isosorbide so as to meet the thermal performance requirements of different film materials.
As a preferable scheme:
the preparation method of the low-crystallinity biodegradable polyester comprises the following specific steps:
(1) a, B, isosorbide and a catalyst are mixed, esterification or ester exchange reaction is carried out under the conditions of inert gas protection, temperature of 150-180 ℃ and pressure of normal pressure (one standard atmospheric pressure) to 5000mbar until the volume of distilled small molecules (such as water, methanol and the like) generated by the reaction reaches more than 90-95% of the theoretical value, and esterification or ester exchange products are prepared;
(2) keeping the system in the step (1) at 180-200 ℃, simultaneously vacuumizing to 10-100 mbar, and reacting for 0.5-2 h to obtain a prepolymer;
(3) and (3) heating the system obtained in the step (2) to 180-220 ℃, simultaneously vacuumizing to 0.01-1 mbar, and reacting for 1-3 h to obtain the low-crystallinity biodegradable polyester.
The thermal stability of furan dicarboxylic acid containing a cyclic ether structure and isosorbide is relatively low, and the esterification reaction in the step (1) is carried out at a relatively mild temperature to prevent thermal degradation; the prepolymerization in the step (2) can be carried out under a medium vacuum degree, the vacuum degree needs to be gradually reduced, the purpose is mainly to prevent the esterification product from being violently boiled under a reduced pressure condition so as to cause unbalance of hydroxyl-carboxyl ratio, meanwhile, the thermal stability is gradually improved along with the growth of a polymer chain, and the purpose of slowly increasing the temperature is to further avoid serious thermal degradation; the final polycondensation in the step (3) needs to be carried out under high vacuum degree, and the main purpose is to efficiently remove excessive dihydric alcohol in a polymerization system, so that the hydroxyl-carboxyl ratio is as close to 1 as possible, and the molecular weight and the viscosity of the polymer are improved.
In the method for preparing the low-crystallinity biodegradable polyester, the furan dicarboxylic acid is one or more of furan-2, 5-dicarboxylic acid, furan-3, 4-dicarboxylic acid and furan-2, 4-dicarboxylic acid, and the alkyl ester of the furan dicarboxylic acid is methyl ester of the furan dicarboxylic acid or alkyl ester with 2-18 carbon atoms;
the aliphatic diol is more than one of ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 4-pentanediol, 2, 4-pentanediol, 1, 6-hexanediol, 1, 5-hexanediol, 1, 4-hexanediol, 2, 5-hexanediol, 3, 4-hexanediol and cyclohexane-1, 4-dimethanol;
the catalyst is titanium catalyst, antimony catalyst, tin catalyst or metal acetate.
According to the preparation method of the low-crystallinity biodegradable polyester, the titanium catalyst is tetrabutyl titanate or tetraisopropyl titanate, the antimony catalyst is antimony trioxide, the tin catalyst is more than one of dibutyltin oxide, butylstannic acid, stannous octoate and 2-ethyl stannous hexanoate, and the metal acetate is more than one of zinc acetate, magnesium acetate, manganese acetate, calcium acetate, sodium acetate and cobalt acetate.
According to the preparation method of the low-crystallinity biodegradable polyester, the ratio of the molar weight of A to the sum of the molar weight of B and isosorbide is 1: 1.1-2.0, the complete esterification of dibasic acid is realized by controlling the excess of the dihydric alcohol, and the excess dihydric alcohol can be removed by utilizing the subsequent high vacuum degree, so that the hydroxyl-carboxyl ratio balance is realized; if the dihydric alcohol is too excessive, the difficulty of vacuum removal is increased, the reaction time is long, and 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 dihydric alcohol are strictly added according to the proportion of 1:1, a great deal of dihydric alcohol volatilizes in the high-temperature polymerization process, the hydroxyl-carboxyl ratio is unbalanced, and a high-molecular-weight polymer cannot be prepared; the molar weight of the isosorbide accounts for 10-100% of the sum of the molar weight of the B and the isosorbide, and when the content of the isosorbide is lower than 10%, the copolyester still has good crystallinity, so that high light transmittance and low haze cannot be realized; within 10-100%, the compound can jointly play a role of efficiently inhibiting crystallization with the furan diacid monomer; the molar ratio of the catalyst to A is 50-1000 ppm, the catalyst cannot be effectively polymerized if the dosage of the catalyst is too low, the reaction time is slow, and waste is caused if the dosage of the catalyst is too high.
The preparation method of the low-crystallinity biodegradable polyester is characterized in that a heat stabilizer and an antioxidant are also added in the step (1) or the step (2);
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 Irganox1010, Irganox1076 and Irganox 1425;
the addition amounts of the heat stabilizer and the antioxidant are respectively 0.1-2% and 0.1-2% of the sum of the masses of A, B and isosorbide, and 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.
After the step (3), the low-crystallinity biodegradable polyester is further purified to remove yellowing products generated by thermal degradation of the copolyester and absorb light in certain specific wavelength ranges, so as to eliminate interference of the yellowing products on the light transmittance of the polyester, and the purification steps are as follows:
(1) dissolving low-crystallinity biodegradable polyester in a decoloring and purifying solvent to obtain a solution, wherein the decoloring and purifying solvent comprises a component S1 and a component S2, the component S1 is hexafluoroisopropanol, and the component S2 is more than one of chloroform, dichloromethane and carbon tetrachloride;
(2) adding activated carbon particles into the solution obtained in the step (1), heating to boiling and refluxing for 30-60 min, and then removing the activated carbon and the decoloration purification solvent;
(3) the low-crystalline biodegradable polyester is dried to a constant weight.
In the preparation method of the low-crystallinity biodegradable polyester, the volume of the component S1 is 30-100% of the total volume of the component S1 and the component S2, and if the volume is less than 30%, the polyester may be difficult to dissolve or the dissolving time is too long; the addition amount of the activated carbon particles is 1-10 wt% of the total mass of the low-crystallinity biodegradable polyester, the addition amount is less than the range, the decoloring effect is not ideal, the addition amount is higher than the range, the decoloring agent waste is caused, and meanwhile, the activated carbon removal difficulty is increased.
According to the preparation method of the low-crystallinity biodegradable polyester, after purification, the b value of the low-crystallinity biodegradable polyester is reduced from 5-10 to 1-4.
The invention also provides the low-crystallinity biodegradable polyester prepared by the preparation method of the low-crystallinity biodegradable polyester, and the molecular chain mainly comprises an A chain segment, a B chain segment and an isosorbide chain segment; the melting enthalpy of the low-crystallinity biodegradable polyester is less than 10J/g.
Has the advantages that:
(1) the preparation method of the low-crystallization biodegradable polyester can effectively reduce the content of thermal degradation byproducts generated in the high-temperature polymerization process of the copolyester, reduce the yellowing of the product and avoid the interference of the product on the light transmittance when preparing a subsequent film product;
(2) the biodegradable polyester prepared by the preparation method of the low-crystallization biodegradable polyester has low crystallinity and good biodegradability;
(3) the biodegradable polyester prepared by the preparation method of the low-crystallization biodegradable polyester has high content of bio-based monomers, low content of petroleum-based aromatic monomers and low overall carbon footprint.
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
A preparation method of low-crystallinity biodegradable polyester comprises the following steps:
(1) esterification reaction: mixing furan-2, 5-dicarboxylic acid (A), ethylene glycol (B), isosorbide, trimethyl phosphate (thermal stabilizer), Irganox1010 (antioxidant) and tetrabutyl titanate (catalyst), and then carrying out esterification reaction under the conditions of nitrogen protection, temperature of 150 ℃ and normal pressure until H generated by the reaction is obtained2Ending when the volume of the distilled O reaches 95 percent of the theoretical value to prepare an esterification product; wherein the ratio of the molar amount of furan-2, 5-dicarboxylic acid to the sum of the molar amounts of ethylene glycol and isosorbide is 1: 1.1; the molar amount of isosorbide represents 10% of the sum of the molar amounts of ethylene glycol and isosorbide; the molar ratio of tetrabutyl titanate to furan-2, 5-dicarboxylic acid is 50ppm, and the addition amounts of trimethyl phosphate and Irganox1010 are respectively 0.1 wt% and 0.1 wt% of the sum of the masses of furan-2, 5-dicarboxylic acid, ethylene glycol and isosorbide;
(2) pre-polycondensation reaction: heating the system in the step (1) to 180 ℃, simultaneously vacuumizing to 10mbar, and reacting for 1.5h to obtain a prepolymer;
(3) and (3) final polycondensation reaction: heating the system in the step (2) to 180 ℃, simultaneously vacuumizing to 0.01mbar, and reacting for 2h to obtain low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 6;
(4) dissolving the low-crystallinity biodegradable polyester obtained in the step (3) in a decoloring and purifying solvent to obtain a solution, wherein the decoloring and purifying solvent comprises hexafluoroisopropanol and chloroform, and the volume of the hexafluoroisopropanol is 30% of the total volume of the hexafluoroisopropanol and the chloroform;
(5) adding activated carbon particles into the solution obtained in the step (4), heating to boiling and refluxing for 60min, and then removing the activated carbon and the decoloration purification solvent; the adding amount of the active carbon particles is 1 wt% of the total mass of the low-crystallinity biodegradable polyester;
finally, drying the low-crystallinity biodegradable polyester to constant weight to obtain the low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 2; the melting enthalpy of the low-crystallinity biodegradable polyester is 3J/g.
Comparative example 1
A process for producing a biodegradable polyester, which comprises the steps substantially the same as those in example 1, except that furan-2, 5-dicarboxylic acid in the step (1) is replaced with terephthalic acid, to give a biodegradable polyester having a melting enthalpy of 41J/g.
Comparing example 1 with comparative example 1, it can be seen that the crystallinity of the polyester prepared in example 1 is lower because the terephthalic acid in comparative example 1 cannot cooperate with isosorbide to hinder the crystallization behavior of the polyester, and unlike furan-2, 5-dicarboxylic acid, terephthalic acid has a symmetrical molecular structure with an angle of 180 ° between two carboxyl functional groups, and the copolyester segment formed by the reaction with isosorbide has a regular conformation and is liable to form a crystalline structure.
Comparative example 2
A process for producing a biodegradable polyester, which comprises the steps substantially the same as those of example 1, except that isosorbide is replaced with isomannide in the step (1), and the fusion enthalpy of the biodegradable polyester obtained is 45J/g.
Comparing example 1 with comparative example 2, it can be seen that the crystallinity of the polyester prepared in example 1 is lower because isomannide in comparative example 2 cannot generate synergistic effect with furan-2, 5-dicarboxylic acid, which hinders the crystallization behavior of the polyester, and unlike isosorbide, two hydroxyl functional groups of isomannide are in endo-steric conformation, have symmetrical molecular configuration, and the copolyester segment formed by the reaction with dicarboxylic acid is easy to form a crystalline structure.
Example 2
A preparation method of low-crystallinity biodegradable polyester comprises the following steps:
(1) ester exchange reaction: after mixing methyl furandicarboxylate, 1, 4-butanediol, isosorbide, trimethyl phosphate, Irganox1010 and stannous octoate, carrying out ester exchange reaction under the protection of argon gas and at the temperature of 160 ℃ and under the condition of 2000mbar until the volume of distilled methanol generated by the reaction reaches 92% of a theoretical value, and preparing an ester exchange product; wherein the ratio of the molar weight of the methyl furandicarboxylate to the sum of the molar weights of 1, 4-butanediol and isosorbide is 1: 1.8; the molar quantity of the isosorbide accounts for 50 percent of the sum of the molar quantities of the 1, 4-butanediol and the isosorbide; the molar ratio of stannous octoate to furan dicarboxylic acid methyl ester is 300ppm, and the addition amounts of trimethyl phosphate and Irganox1010 are respectively 0.5 wt% and 0.5 wt% of the sum of the masses of furan dicarboxylic acid methyl ester, 1, 4-butanediol and isosorbide;
(2) pre-polycondensation reaction: heating the system in the step (1) to 190 ℃, simultaneously vacuumizing to 30mbar, and reacting for 2h to obtain a prepolymer;
(3) and (3) final polycondensation reaction: heating the system in the step (2) to 200 ℃, simultaneously vacuumizing to 0.1mbar, and reacting for 1.5h to obtain low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 5;
(4) dissolving the low-crystallinity biodegradable polyester obtained in the step (3) in a decoloring and purifying solvent to obtain a solution, wherein the decoloring and purifying solvent comprises hexafluoroisopropanol and dichloromethane, and the volume of the hexafluoroisopropanol is 60% of the total volume of the hexafluoroisopropanol and the dichloromethane;
(5) adding activated carbon particles into the solution obtained in the step (4), heating to boiling and refluxing for 45min, and then removing the activated carbon and the decoloration purification solvent; the adding amount of the active carbon particles is 4 wt% of the total mass of the low-crystallinity biodegradable polyester;
finally, drying the low-crystallinity biodegradable polyester to constant weight to obtain the low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 1; the melting enthalpy of the low-crystallinity biodegradable polyester is 5J/g.
Example 3
A preparation method of low-crystallinity biodegradable polyester comprises the following steps:
(1) esterification reaction: mixing furan-2, 5-dicarboxylic acid, 2, 4-pentanediol, isosorbide and zinc acetate, and performing esterification reaction under the conditions of nitrogen protection, 165 ℃ temperature and 3500mbar pressure until H generated by the reaction2Ending when the volume of the distilled O reaches 95 percent of the theoretical value to prepare an esterification product; wherein the ratio of the molar weight of furan-2, 5-dicarboxylic acid to the sum of the molar weights of 2, 4-pentanediol and isosorbide is 1: 1.5; the molar amount of isosorbide is 2, 4-pentan65% of the sum of the molar amounts of diol and isosorbide; the molar ratio of the zinc acetate to the furan-2, 5-dicarboxylic acid is 600 ppm;
(2) pre-polycondensation reaction: heating the system in the step (1) to 205 ℃, adding triphenyl phosphite and a mixture of Irganox1010, Irganox1076 and Irganox1425 in a mass ratio of 1:1:1, simultaneously vacuumizing to 60mbar, and reacting for 1.2h to obtain a prepolymer; wherein, the addition amount of triphenyl phosphite and the mixture of Irganox1010, Irganox1076 and Irganox1425 with the mass ratio of 1:1:1 is respectively 1.5 wt% and 1.5 wt% of the sum of the masses of furan-2, 5-dicarboxylic acid, 2, 4-pentanediol and isosorbide;
(3) and (3) final polycondensation reaction: heating the system in the step (2) to 210 ℃, simultaneously vacuumizing to 1.5mbar, and reacting for 3h to obtain the low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 8;
(4) dissolving the low-crystallinity biodegradable polyester obtained in the step (3) in a decoloring and purifying solvent to obtain a solution, wherein the decoloring and purifying solvent comprises hexafluoroisopropanol and carbon tetrachloride, and the volume of the hexafluoroisopropanol is 50% of the total volume of the hexafluoroisopropanol and the carbon tetrachloride;
(5) adding activated carbon particles into the decoloration purification solvent, heating to boiling and refluxing for 35min, and then removing the activated carbon and the decoloration purification solvent; the adding amount of the activated carbon particles is 7 wt% of the total mass of the low-crystallinity biodegradable polyester;
finally, drying the low-crystallinity biodegradable polyester to constant weight to obtain the low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 4; the melting enthalpy of the low-crystallinity biodegradable polyester was 0.8J/g.
Example 4
A preparation method of low-crystallinity biodegradable polyester comprises the following steps:
(1) ester exchange reaction: after mixing methyl furan dicarboxylate, 3, 4-hexanediol, isosorbide and cobalt acetate, carrying out esterification reaction under the conditions of helium protection, 165 ℃ temperature and 4000mbar pressure until the volume of distilled methanol generated by the reaction reaches 97% of a theoretical value, and preparing an ester exchange product; wherein the ratio of the molar amount of the methyl furandicarboxylate to the sum of the molar amounts of 3, 4-hexanediol and isosorbide is 1: 1.4; the molar amount of isosorbide accounts for 45 percent of the sum of the molar amounts of 3, 4-hexanediol and isosorbide; the molar ratio of cobalt acetate to methyl furandicarboxylate was 500 ppm;
(2) pre-polycondensation reaction: heating the system in the step (1) to 190 ℃, adding phosphorous acid and a mixture of Irganox1010, Irganox1076 and Irganox1425 in a mass ratio of 1:1:1, simultaneously vacuumizing to 35mbar, and reacting for 1h to obtain a prepolymer; wherein, the addition amount of the phosphorous acid and the mixture of Irganox1010, Irganox1076 and Irganox1425 with the mass ratio of 1:1:1 is respectively 1 wt% and 1 wt% of the sum of the mass of the furandicarboxylic acid methyl ester, the 3, 4-hexanediol and the isosorbide;
(3) and (3) final polycondensation reaction: heating the system in the step (2) to 195 ℃, simultaneously vacuumizing to 0.6mbar, and reacting for 2.5h to obtain the low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 10;
(4) dissolving the low-crystallinity biodegradable polyester obtained in the step (3) in a decoloring and purifying solvent to obtain a solution, wherein the decoloring and purifying solvent comprises hexafluoroisopropanol and a mixture of chloroform, carbon tetrachloride and dichloromethane in a mass ratio of 1:1:1, and the volume of the hexafluoroisopropanol is 45% of the total volume of the hexafluoroisopropanol and the mixture of chloroform, carbon tetrachloride and dichloromethane in a mass ratio of 1:1: 1;
(5) adding activated carbon particles into the decoloration purification solvent, heating to boiling and refluxing for 30min, and removing the activated carbon and the decoloration purification solvent; the adding amount of the active carbon particles is 5 wt% of the total mass of the low-crystallinity biodegradable polyester;
finally, drying the low-crystallinity biodegradable polyester to constant weight to obtain the low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 4; the melting enthalpy of the low-crystallinity biodegradable polyester is 1J/g.
Example 5
A preparation method of low-crystallinity biodegradable polyester comprises the following steps:
(1) esterification reaction: mixing furan-2, 5-dicarboxylic acid, isosorbide, hypophosphorous acid, Irganox1010 and tetrabutyl titanate, and performing esterification reaction under the protection of nitrogen, the temperature condition of 180 ℃ and the pressure of 5000mbarUntil H is formed by reaction2Ending when the volume of the distilled O reaches 95 percent of the theoretical value to prepare an esterification product; wherein the ratio of the molar amount of furan-2, 5-dicarboxylic acid to the molar amount of isosorbide is 1: 2; the molar ratio of tetrabutyl titanate to furan-2, 5-dicarboxylic acid is 1000ppm, and the addition amounts of phosphoric acid and Irganox1010 are respectively 2 wt% and 2 wt% of the sum of the masses of furan-2, 5-dicarboxylic acid and isosorbide;
(2) pre-polycondensation reaction: heating the system in the step (1) to 210 ℃, simultaneously vacuumizing to 35mbar, and reacting for 1h to obtain a prepolymer;
(3) and (3) final polycondensation reaction: heating the system in the step (2) to 220 ℃, simultaneously vacuumizing to 1mbar, and reacting for 1h to obtain low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 5;
(4) dissolving the low-crystallinity biodegradable polyester obtained in the step (3) in a decoloring and purifying solvent to obtain a solution, wherein the decoloring and purifying solvent comprises hexafluoroisopropanol and a mixture of dichloromethane and chloroform with a mass ratio of 1:1, and the volume of the hexafluoroisopropanol is 90% of the total volume of the hexafluoroisopropanol and the mixture of dichloromethane and chloroform with a mass ratio of 1: 1;
(5) adding activated carbon particles into the solution obtained in the step (4), heating to boiling and refluxing for 30min, and then removing the activated carbon and the decoloration purification solvent; the adding amount of the active carbon particles is 10wt% of the total mass of the low-crystallinity biodegradable polyester;
finally, drying the low-crystallinity biodegradable polyester to constant weight to obtain the low-crystallinity biodegradable polyester, wherein the b value of the low-crystallinity biodegradable polyester is 3; the melting enthalpy of the low-crystallinity biodegradable polyester is 0J/g.
Example 6
The example 6 is basically the same as the example 5 in terms of steps, except that the step (4) is different, specifically: dissolving the low-crystallinity biodegradable polyester obtained in the step (3) in a decoloring and purifying solvent to obtain a solution, wherein the decoloring and purifying solvent is hexafluoroisopropanol;
the low-crystalline biodegradable polyester obtained in example 6 had a b value of 3; the melting enthalpy of the low-crystallinity biodegradable polyester is 1J/g.
Examples 7 to 19
Examples 7 to 19 were substantially the same as those of example 1 except that the reaction materials in step (1) were as shown in Table 1, and the b values and the enthalpy of fusion of the low-crystalline biodegradable polyesters obtained in examples 7 to 19 were as shown in Table 2.
TABLE 1
Claims (7)
1. A preparation method of low-crystallinity biodegradable polyester is characterized by comprising the following steps:
(1) a, B, isosorbide and a catalyst are mixed, esterification or ester exchange reaction is carried out under the conditions of inert gas protection, temperature of 150-180 ℃ and pressure of normal pressure-5000 mbar, and the reaction is finished when the volume of distilled small molecules generated by the reaction reaches more than 90-95% of the theoretical value, so as to prepare an esterification or ester exchange product; wherein A is furan dicarboxylic acid or alkyl ester thereof, and B is fatty diol; the molar weight of the isosorbide accounts for 45-100% of the sum of the molar weight of the B and the molar weight of the isosorbide; the ratio of the molar weight of A to the sum of the molar weights of B and isosorbide is 1: 1.1-2.0; the molar ratio of the catalyst to the A is 50-1000 ppm;
(2) heating the system in the step (1) to 180-200 ℃, simultaneously vacuumizing to 10-100 mbar, and reacting for 0.5-2 h to obtain a prepolymer;
(3) heating the system in the step (2) to 180-220 ℃, simultaneously vacuumizing to 0.01-1 mbar, and reacting for 1-3 h to obtain the low-crystallinity biodegradable polyester;
purifying the low-crystallinity biodegradable polyester as follows:
(I) dissolving low-crystallinity biodegradable polyester in a decoloring and purifying solvent to obtain a solution, wherein the decoloring and purifying solvent comprises a component S1 and a component S2, the component S1 is hexafluoroisopropanol, and the component S2 is more than one of chloroform, dichloromethane and carbon tetrachloride;
(II) adding activated carbon particles into the solution obtained in the step (I), heating to boiling and refluxing for 30-60 min, and then removing the activated carbon and the decoloration purification solvent;
(III) drying the low-crystallinity biodegradable polyester to constant weight.
2. The method for producing a low-crystallinity biodegradable polyester according to claim 1, wherein the furandicarboxylic acid is one or more of furan-2, 5-dicarboxylic acid, furan-3, 4-dicarboxylic acid and furan-2, 4-dicarboxylic acid, and the alkyl ester of the furandicarboxylic acid is a methyl ester or an alkyl ester having 2 to 18 carbon atoms of the furandicarboxylic acid;
the aliphatic diol is more than one of ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 1, 4-pentanediol, 2, 4-pentanediol, 1, 6-hexanediol, 1, 5-hexanediol, 1, 4-hexanediol, 2, 5-hexanediol, 3, 4-hexanediol and cyclohexane-1, 4-dimethanol;
the catalyst is titanium catalyst, antimony catalyst, tin catalyst or metal acetate.
3. The method for preparing low-crystallinity biodegradable polyester according to claim 2, wherein the titanium catalyst is tetrabutyl titanate or tetraisopropyl titanate, the antimony catalyst is antimony trioxide, the tin catalyst is one or more of dibutyltin oxide, butylstannic acid, stannous octoate and stannous 2-ethylhexanoate, and the metal acetate is one or more of zinc acetate, magnesium acetate, manganese acetate, calcium acetate, sodium acetate and cobalt acetate.
4. The method for preparing low-crystallinity biodegradable polyester according to claim 1, wherein a thermal stabilizer and an antioxidant are further added in step (1) or step (2);
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 Irganox1010, Irganox1076 and Irganox 1425;
the addition amounts of the heat stabilizer and the antioxidant are respectively 0.1-2% and 0.1-2% of the sum of the masses of A, B and isosorbide.
5. The method for preparing low-crystallinity biodegradable polyester according to claim 1, wherein in step (I), the volume of component S1 is 30-100% of the total volume of component S1 and component S2; the adding amount of the activated carbon particles in the step (II) is 1-10 wt% of the total mass of the low-crystallinity biodegradable polyester.
6. The method for preparing low-crystallinity biodegradable polyester according to claim 5, wherein b value of low-crystallinity biodegradable polyester is reduced from 5 to 10 to 1 to 4 after purification.
7. The low-crystallinity biodegradable polyester obtained by the method for producing a low-crystallinity biodegradable polyester according to any one of claims 1 to 6, wherein: the molecular chain mainly comprises an A chain segment, a B chain segment and an isosorbide chain segment; the melting enthalpy of the low-crystallinity biodegradable polyester is less than 10J/g.
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