Block polyester as well as preparation method and application thereof

Abstract

The invention relates to a block polyester material and discloses block polyester as well as a preparation method and application thereof. The polyester contains a block structure A as shown in a formula (I), a block structure B as shown in a formula (II) and a structure C as shown in a formula (III), the mass ratio of the structure A to the structure B in the polyester is 1: (1.5-9), R1 and R2 are respectively and independently alkylene of C2-C5, R3 is alkylene of C4-C18, and R4 is alkyl residues of diisocyanate. The polyester has better rebound resilience and biodegradability. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to polyester materials, in particular to a segmented polyester and a preparation method and application thereof. Background Art

[0002] Thermoplastic polyester elastomer (TPEE) is a copolymer of high melting point polyester (such as PET, PBT, etc.) or high hardness crystalline short chain polyester (such as PLA) as hard segment, amorphous long chain polyether (such as polyethylene glycol ether, polypropylene glycol ether, polybutylene glycol ether, etc.) or polyester (such as polycaprolactone and other aliphatic polyesters) as soft segment to form ABA type triblock or (AB) n Type multi-block copolymer.

[0003] Compared to random copolymers, the "sea-island" structure formed in block copolymer systems due to the incompatibility of the hard and soft segments can maintain the mechanical strength of the hard segments and the flexibility of the soft segments. In the research of block copolyesters, 2,5-furandicarboxylic acid polyester or terephthalic acid is mostly used as the hard segment. For example, Chinese patent application CN110407991A discloses multi-block copolymers with 2,5-furandicarboxylic acid polyester as the hard segment and aliphatic polycarbonate as the soft segment. When the 2,5-furandicarboxylic acid polyester content of the hard segment is 50-99wt%, the multi-block copolymer has a low elongation at break of only 32-68%, and the tensile recovery of the block copolymer is also low.

[0004] Moreover, although the prior art CN112062939A discloses that a polyester with good biodegradability and resilience is prepared using aliphatic diols, aliphatic dibasic acids and diphenyl ether dicarboxylic acid as monomers, studies have found that the tensile recovery rate of the polyester is low, indicating that its resilience needs to be further improved. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems in the prior art of low elongation at break and tensile recovery of multi-block copolymers formed from 2,5-furandicarboxylic acid polyester and aliphatic polycarbonate, and low tensile recovery of polyesters prepared from aliphatic diols, aliphatic dibasic acids and diphenyl ether dicarboxylic acid, and to provide a block polyester, a preparation method and application thereof.

[0006] During the research process, the inventors unexpectedly discovered that when polyester contains structure A represented by formula (I), structure B represented by formula (II), and structure C represented by formula (III), and the mass ratio of structure A to structure B is 1:1.5-9, the synergistic effect between the above three structures at specific contents can significantly improve the tensile recovery rate of the polyester, thereby making the polyester have better resilience and facilitating subsequent processing.

[0007] In order to achieve the above object, the first aspect of the present invention provides a block polyester, which contains structure A, structure B and structure C, and in the block polyester, the mass ratio of the structure A to the structure B is 1:1.5-9;

[0008] The structure A is shown in formula (I):

[0009] The structure B is shown in formula (II):

[0010] The structure C is shown in formula (III):

[0011] Wherein, R1 and R2 are each independently a C2-C5 alkylene group, R3 is a C4-C18 alkylene group, and R4 is a hydrocarbon residue of a diisocyanate.

[0012] A second aspect of the present invention provides a method for preparing a block polyester, comprising the following steps:

[0013] (1) mixing monomer a represented by formula (V), monomer b represented by formula (VI) and a catalyst, and then subjecting them to an esterification reaction and then a polycondensation reaction to obtain a prepolymer diol I having a structure of formula (I);

[0014] The monomer c represented by formula (VII), the monomer d represented by formula (VIII) and the catalyst are mixed and first subjected to esterification reaction and then polycondensation reaction to obtain a prepolymer diol II with the structure of formula (II);

[0015]

[0016] wherein R1 and R2 are each independently a C2-C5 alkylene group, R3 is a C4-C18 alkylene group, and R5, R6, R7 and R8 are each independently a methyl group or hydrogen;

[0017] (2) reacting the prepolymer diol I, the prepolymer diol II, a diisocyanate and a catalyst under chain extension reaction conditions, wherein the mass ratio of the prepolymer diol I to the prepolymer diol II is 1:1.5-9.

[0018] The third aspect of the present invention provides the use of the above-mentioned block polyester or the block polyester prepared by the above-mentioned preparation method in medical elastic materials.

[0019] The polyester provided by the present invention contains structure A represented by formula (I), structure B represented by formula (II), and structure C represented by formula (III). The mass ratio of structure A to structure B is 1:1.5-9. Through the synergistic effect of the three structures at specific contents, the stretch recovery rate of the polyester can be significantly improved, so that the recovery rate of the polyester after 10 cyclic stretching cycles is greater than or equal to 70%, thereby making the polyester have better rebound elasticity and facilitating subsequent processing. It also has good biodegradability, does not produce white pollution, is environmentally friendly, and has broad application prospects.

[0020] The preparation method of the present invention forms a multi-block polyester by performing a chain extension polymerization reaction on prepolymer diol I and prepolymer diol II using diisocyanate, thereby achieving controllable multi-block sequence structure. In addition, the prepared polyester has a high tensile recovery rate and good biodegradability, and has important application value in the fields of high resilience, degradable and thermoplastic polymer materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the H NMR spectrum of the polyester prepared in Example 1 of the present invention.

[0022] Figure 2 The DSC curves of the polyesters prepared in Example 3 and Comparative Example 1 of the present invention are shown.

[0023] Figure 3 These are the stress-strain curves of the polyesters prepared in Example 3 of the present invention and Comparative Example 1.

[0024] Figure 4 This is the cyclic stretching curve of the polyester prepared in Example 3 of the present invention;

[0025] Figure 5 This is the cyclic stretching curve of the polyester prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0027] As mentioned above, the first aspect of the present invention provides a block polyester, which contains structure A, structure B and structure C, and in the block polyester, the mass ratio of the structure A to the structure B is 1:1.5-9;

[0028] The structure A is shown in formula (I):

[0029] The structure B is shown in formula (II):

[0030] The structure C is shown in formula (III):

[0031] Wherein, R1 and R2 are each independently a C2-C5 alkylene group, R3 is a C4-C18 alkylene group, and R4 is a hydrocarbon residue of a diisocyanate.

[0032] In polyester, the composition of structure A and structure B can be detected by nuclear magnetic hydrogen spectrum and carbon spectrum analysis, and the molar ratio of structure A and structure B can be calculated by carbon spectrum analysis of the ratio of the nuclear magnetic peak area of ​​the benzene ring (derived from structure A) to the nuclear magnetic peak area of ​​the carbonyl group (derived from structure A and structure B), and the mass ratio of structure A and structure B can be further calculated.

[0033] During their research, the inventors unexpectedly discovered that when a polyester simultaneously contains Structure A represented by Formula (I), Structure B represented by Formula (II), and Structure C represented by Formula (III), with a mass ratio of Structure A to Structure B of 1:1.5-9, the synergistic effect between the three structures at specific concentrations can significantly improve the stretch recovery rate of the polyester, resulting in a recovery rate of greater than or equal to 70% after 10 stretch cycles. This polyester exhibits improved resilience and facilitates subsequent processing. Furthermore, this polyester exhibits good biodegradability, reduces white pollution during use, and is environmentally friendly, with broad application prospects.

[0034] According to the present invention, n is 6-21, specifically 6, 9, 12, 15, 18, 21, or any value between these values; m is 5-41, specifically 5, 11, 17, 23, 29, 35, 41, or any value between these values.

[0035] According to the present invention, preferably, the block polyester has a structural formula as shown in formula (IV):

[0036]

[0037] In order to further improve the multiple stretching recovery rate and biodegradability of polyester, preferably, the mass ratio of the structure A to the structure B is 1:2.3-4.

[0038] R4 can be any divalent group. As a specific embodiment of the present invention, R4 is a C4-C8 chain alkylene, a C10-C15 cyclic alkylene, a divalent phenyl, a methyl-substituted divalent phenyl, or a divalent aralkyl containing two benzene rings. Specifically, the C4-C8 alkylene can be n-butylene, methylpropylene, n-pentylene, methylbutylene, dimethylpropylene, ethylpropylene, n-hexylene, methylpentylene, dimethylbutylene, ethylbutylene, etc., preferably n-hexylene. The divalent aralkyl containing two benzene rings can be The C10-C15 cyclic alkylene group can be

[0039] Preferably, the polyester has a recovery rate of greater than or equal to 65% after 10 stretch cycles, and a degradation rate of greater than or equal to 70% after seven months of composting at a thickness of 0.2 mm. Polyesters under these conditions exhibit good resilience and biodegradability, good processability, and reduced environmental pollution. To further enhance the resilience and biodegradability of the polyester, it is further preferred that the polyester have a recovery rate of 75-80% after 10 stretch cycles, and a degradation rate of greater than or equal to 70% after six months of composting at a thickness of 0.2 mm.

[0040] According to the present invention, the rebound rate is tested using a Physica MCR 301 rotational rheometer (Anton Pear, Germany) to analyze the cyclic tensile properties of the sample. The test is performed in tensile mode at room temperature (25°C) at a rate of 50 mm / min until the specimen reaches a strain of 200%. The specimen is then returned to its original length at a rate of -50 mm / min, forming one cycle. Ten cycles of cyclic stretching are repeated to obtain a stress-strain curve. The extreme rebound rate is determined based on the stress-strain curve.

[0041] Composting Degradation Test: Polyester was hot-pressed into sheets with an average thickness of 0.2 mm using a flatbed vulcanizer, then cut into 10 mm x 10 mm pieces. Following ISO 14855, copolyester samples were subjected to composting tests under controlled composting conditions. The ultimate aerobic biodegradability of the copolyester was determined by measuring the amount of CO2 emitted.

[0042] Specifically, 60g of culture soil was used as a blank control sample, 60g of culture soil was mixed with 10g of copolyester film as an experimental sample, and 60g of culture soil was mixed with 10g of cellulose as a positive control sample. Distilled water was added to adjust the relative humidity of the control sample and the experimental sample to about 50%, and the samples were fully mixed and then placed in a compost container. The compost container was placed in an experimental environment (58±2°C) and aerated with water-saturated air that had been decarbonized. The compost container was shaken once a week to ensure that the microorganisms were in full contact with the sample, and the compost was carried out for 180-240 days. The CO2 released during the experiment was absorbed by NaOH solution, and the amount of CO2 released was determined by titration analysis every 24 hours. The biodegradation rate D of the sample was calculated based on the ratio of the actual cumulative amount of CO2 released to the theoretical CO2 release of the sample. t , the calculation formula is as follows:

[0043]

[0044] Where, T CO2 Indicates the cumulative amount of CO2 released from the compost container containing the experimental sample; B CO2 Indicates the cumulative amount of CO2 released from the compost container containing the blank sample; Th CO2 It represents the theoretical amount of CO2 released by the experimental sample, which is measured using a total organic carbon analyzer.

[0045] Preferably, the polyester has a tensile strength of 10-30 MPa and an elongation at break of 550-1000%. The polyester provided above has good mechanical properties and is convenient for subsequent processing and application.

[0046] According to the present invention, a Shenzhen Kaiqiangli WD-II 10 electronic universal testing machine is used to measure according to GB / T 1040-1992 to obtain a stress-strain curve during the fracture process, and the tensile strength and elongation at break are obtained based on the stress-strain curve. A German NETZSCH DSC-4000 differential scanning calorimeter is used for testing. A 3-5 mg sample is placed in a crucible and tested under a nitrogen flow rate of 40 mL / min, a heating rate of 10°C / min, and a temperature range of 20-240°C. The glass transition temperature is obtained by analysis.

[0047] A second aspect of the present invention provides a method for preparing a block polyester, comprising the following steps:

[0048] (1) mixing monomer a represented by formula (V), monomer b represented by formula (VI) and a catalyst, and then subjecting them to an esterification reaction and then a polycondensation reaction to obtain a prepolymer diol I having a structure of formula (I);

[0049] The monomer c represented by formula (VII), the monomer d represented by formula (VIII) and the catalyst are mixed and first subjected to esterification reaction and then polycondensation reaction to obtain a prepolymer diol II with the structure of formula (II);

[0050]

[0051] wherein R1 and R2 are each independently a C2-C5 alkylene group, R3 is a C4-C18 alkylene group, and R5, R6, R7 and R8 are each independently a methyl group or hydrogen;

[0052] (2) reacting the prepolymer diol I, the prepolymer diol II, a diisocyanate, and a catalyst under chain extension reaction conditions, wherein the molar ratio of the sum of the moles of the prepolymer diol I and the prepolymer diol II to the diisocyanate is 1:1.05-1:1.10.

[0053] According to the present invention, the termination condition of the esterification reaction can be determined by the experimenter based on actual conditions, preferably based on the amount of water in the product. Specifically, the termination condition of the esterification reaction is when the amount of water collected reaches 80% of the theoretical value. R5, R6, R7, and R8 are each independently methyl or hydrogen. Preferably, methyl. When R5, R6, R7, and R8 are each independently methyl, the transesterification reaction proceeds more easily. The esterification reaction time is generally 3-4 hours.

[0054] The termination conditions of the polycondensation reaction can also be determined by the experimenter according to actual conditions.

[0055] The end condition of the chain extension reaction can also be determined by the experimenter according to the actual situation. Specifically, the chain extension reaction time is generally 1-4 hours.

[0056] For example, the monomer d can be 1,4-butanedioic acid, 1,4-dimethyl butanedioate, 1,5-pentanedioic acid, 1,5-dimethyl glutarate, 1,6-hexanedioic acid, 1,6-methyl hexanedioate, 1,7-heptanedioic acid, 1,7-dimethyl heptanedioate, 1,8-octanedioic acid, 1,8-methyl suberate, 1,9-nonanedioic acid, 1,9-nonanedioic acid dimethyl ester, 1,10-decanedioic acid, 1,10-dimethyl sebacate, 1,11-undecanedioic acid, 1,11-undecanedioic acid, 1,1 At least one of 2-dodecanedioic acid, 1,12-dodecanedioic acid dimethyl ester, 1,13-tridecanedioic acid, 1,13-tridecanedioic acid methyl ester, 1,14-tetradecanedioic acid, 1,14-tetradecanedioic acid dimethyl ester, 1,15-pentadecanedioic acid, 1,15-pentadecanedioic acid dimethyl ester, 1,16-hexadecanedioic acid, 1,16-hexadecanedioic acid dimethyl ester, 1,17-heptadecanedioic acid, 1,17-heptanedioic acid dimethyl ester, 1,18-octadecanedioic acid and 1,18-octadecanedioic acid dimethyl ester.

[0057] During the research process, the inventors discovered that the above preparation method uses diisocyanate to carry out a chain extension polymerization reaction on prepolymer diol I and prepolymer diol II to form a multi-block polyester, thereby achieving the controllability of the multi-block sequence structure. In addition, the prepared polyester has a high multiple stretching recovery rate and good biodegradability, and has important application value in the fields of high rebound, degradable and thermoplastic polymer materials.

[0058] Preferably, in step (1), the monomer b is selected from at least one of 3,3'-diphenylether dicarboxylic acid, 3,3'-diphenylether dicarboxylic acid dimethyl ester, 4,4'-diphenylether dicarboxylic acid, and 4,4'-diphenylether dicarboxylic acid dimethyl ester; and the catalyst is an organic titanium catalyst. Further preferably, the organic titanium catalyst is tetrabutyl titanate and / or tetraethyl titanate.

[0059] Preferably, the molar ratio of monomer a to monomer b is 1.5-2:1, and the molar ratio of monomer c to monomer d is 1.1-1.2:1. Under these molar ratios, monomer a and monomer b react well, as do monomer c and monomer d, and the raw materials have a high utilization rate. Furthermore, the polyester prepared under these conditions has a high multiple stretch recovery rate and good biodegradability.

[0060] Preferably, during the reaction of monomers a and b, the amount of catalyst added is 0.002-0.006 mol relative to 1 mol of monomer b; during the reaction of monomers c and d, the amount of catalyst added is 0.002-0.006 mol relative to 1 mol of monomer d. The polyester prepared under these conditions has a high multiple stretch recovery rate and good biodegradability.

[0061] Preferably, in step (1), the esterification reaction conditions include at least: isolation of oxygen, a temperature of 160-180°C, specifically 160°C, 165°C, 170°C, 175°C, 180°C, or any value between the aforementioned values; and a time of 3-4 hours, specifically 3 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4 hours, or any value between the aforementioned values. Under the above conditions, a better esterification effect is achieved. Isolation of oxygen is usually achieved by filling the reaction system with an inert gas such as nitrogen or helium.

[0062] In step (1), the polycondensation reaction conditions include at least: a temperature of 220-240°C, specifically 220°C, 225°C, 230°C, 235°C, 240°C, or any value between the aforementioned values; and an absolute vacuum degree of less than or equal to 50 Pa. Preferably, the number average molecular weight of the prepolymer diol I is 2000-6000 g / mol, and the number average molecular weight of the prepolymer diol II is 2000-6000 g / mol. Controlling the number average molecular weights of the prepolymer diol I and the prepolymer diol II independently within the range of 2000-6000 g / mol facilitates subsequent reactions, thereby enabling the prepared polyester to have a higher multiple stretch recovery rate without causing environmental pollution or energy waste. During research, the inventors unexpectedly discovered that when the number average molecular weight of either prepolymer diol I or prepolymer diol II is controlled below 2000 g / mol, the multiple stretch recovery rate of the prepared polyester decreases. When the number average molecular weight of either prepolymer diol I or prepolymer diol II is controlled above 6000 g / mol, the viscosity of prepolymer diol I or prepolymer diol II is relatively high, and during the reaction in step (2), an organic solvent must be added to reduce the viscosity of the system, which causes environmental pollution and wastes energy.

[0063] Preferably, the glass transition temperature of the prepolymer diol I is greater than 40° C. Using the prepolymer diol I with a glass transition temperature greater than 40° C. can further improve the multiple stretching recovery rate of the subsequent polyester.

[0064] Preferably, in step (2), the diisocyanate is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate; and the catalyst is an organotin catalyst. Further preferably, the organotin catalyst is stannous octoate and / or dibutyltin dilaurate.

[0065] Preferably, in step (2), the molar ratio of the sum of the moles of the prepolymer diol I and the prepolymer diol II to the diisocyanate is 1:1.05-1.1. The polyester prepared under the above conditions has a higher multiple stretch recovery rate and better biodegradability. In order to further improve the stretch recovery rate and biodegradability of the polyester, it is further preferred that the amount of the catalyst added is 0.005-0.008g relative to 1g of diisocyanate. The polyester prepared under the above conditions has a higher multiple stretch recovery rate and better biodegradability.

[0066] Preferably, the chain extension reaction conditions at least include: isolating oxygen, the temperature is 130-150° C., and the reaction time is 1-4 hours. The polyester prepared under the above conditions has a higher multiple stretching recovery rate and better biodegradability.

[0067] Preferably, the method further comprises purifying the prepolymer diol I and prepolymer diol II obtained in step (1) respectively. The purification method can be a method commonly used in the art. Preferably, the prepolymer diol I and prepolymer diol II obtained in step (1) are dissolved in chloroform, precipitated with methanol, filtered and dried to obtain purified prepolymer diol I and prepolymer diol II.

[0068] The third aspect of the present invention provides the use of the polyester or the polyester prepared by the above preparation method in medical elastic materials.

[0069] The above-mentioned material has good resilience and biodegradability, and has good application effect in medical elastic materials.

[0070] Preferably, the medical elastic material is a disposable medical elastomer and / or a rebound strip for diapers.

[0071] According to a particularly preferred embodiment of the present invention, the method for preparing the polyester comprises the following steps:

[0072] (1) subjecting a monomer a represented by formula (V) and a monomer b represented by formula (VI) in a molar ratio of (1.5-2):1:(0.002-0.006) to an esterification reaction for 3-4 hours under a nitrogen atmosphere at a temperature of 160-180° C.; and then subjecting the monomer a to a polycondensation reaction at a temperature of 220-240° C. and an absolute vacuum of less than or equal to 50 Pa to obtain a prepolymer diol I having a number average molecular weight of 2000-6000 g / mol and a glass transition temperature greater than 40° C.;

[0073] A monomer c represented by formula (VII), a monomer d represented by formula (VIII), and a catalyst in a molar ratio of (1.1-1.2):1:(0.002-0.006) are subjected to an esterification reaction for 3-4 hours under an N2 atmosphere and a temperature of 160-180°C; a polycondensation reaction is carried out at a temperature of 220-240°C and an absolute vacuum degree of less than or equal to 50 Pa to obtain a prepolymer diol II with a number average molecular weight of 2000-6000 g / mol;

[0074] The catalyst is tetrabutyl titanate and / or tetraethyl titanate.

[0075]

[0076] wherein R1 and R2 are each independently a C2-C5 alkylene group, R3 is a C4-C18 alkylene group, and R5, R6, R7 and R8 are each independently a methyl group or hydrogen;

[0077] (2) reacting the prepolymer diol I and the prepolymer diol II in a mass ratio of 1:1.5-9, a diisocyanate (1.05-1.10 of the total molar amount of the prepolymer diol), and a catalyst (0.5-0.8% of the total mass of the prepolymer diol) under a nitrogen atmosphere at a temperature of 130-150° C. for 1-4 hours to obtain a polyester;

[0078] The diisocyanate is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate, and the catalyst is stannous octoate and / or dibutyltin dilaurate.

[0079] The polyester prepared by the above method has better resilience and biodegradability. The method is simple to operate, has strong process controllability, and is easy to industrialize.

[0080] The present invention will be described in detail below through examples.

[0081] In the following examples, the raw materials used were purchased from commercial sources and were all chemically pure.

[0082] (1) H NMR Spectroscopy: The chemical structure of the polyester was analyzed using a Bruker Avance III 400 MHz H NMR spectrometer. Deuterated chloroform (CDCl3) was used as a good solvent for the polyester.

[0083] (2) Differential Scanning Calorimetry (DSC): The test was performed using a DSC-4000 differential scanning calorimeter from NETZSCH, Germany. 3-5 mg of the sample was placed in a crucible and tested at a nitrogen flow rate of 40 mL / min, a heating rate of 10 °C / min, and a temperature range of 20-240 °C.

[0084] (3) Tensile strength at break: The stress-strain curve of the fracture process was obtained by measuring the tensile strength using a Shenzhen Kaiqiangli WD-II 10 electronic universal testing machine according to GB / T 1040-1992.

[0085] (4) Cyclic Tensile: The cyclic tensile properties of the samples were analyzed using a Physica MCR 301 rotational rheometer from Anton Pear, Germany. The test was performed in tensile mode at room temperature (25°C) at a rate of 50 mm / min until the specimen reached a strain of 200%. The specimen was then returned to its original length at a rate of -50 mm / min, forming one cycle. Ten cycles of back-and-forth stretching were repeated to obtain the stress-strain curves of the cyclic tensile tests.

[0086] (5) Composting Degradation Test: The copolyester was hot-pressed into sheets with an average thickness of 0.2 mm using a flat-bed vulcanizer, and then cut into 10 mm × 10 mm pieces. Following ISO 14855, the copolyester samples were subjected to composting degradation tests under controlled composting conditions. The ultimate aerobic biodegradability of the copolyester was determined by measuring the amount of CO2 emitted.

[0087] Specifically, 60g of culture soil was used as a blank control sample, 60g of culture soil was mixed with 10g of copolyester film as an experimental sample, and 60g of culture soil was mixed with 10g of cellulose as a positive control sample. Distilled water was added to adjust the relative humidity of the control sample and the experimental sample to about 50%, and the samples were fully mixed and then placed in a compost container. The compost container was placed in an experimental environment (58±2°C) and aerated with water-saturated air that had been decarbonized. The compost container was shaken once a week to ensure that the microorganisms were in full contact with the sample, and the compost was carried out for 180-240 days. The CO2 released during the experiment was absorbed by NaOH solution, and the amount of CO2 released was determined by titration analysis every 24 hours. The biodegradation rate D of the sample was calculated based on the ratio of the actual cumulative amount of CO2 released to the theoretical CO2 release of the sample. t , the calculation formula is as follows:

[0088]

[0089] Where, T CO2 Indicates the cumulative amount of CO2 released from the compost container containing the experimental sample; B CO2 Indicates the cumulative amount of CO2 released from the compost container containing the blank sample; Th CO2 It represents the theoretical amount of CO2 released by the experimental sample, which is measured using a total organic carbon analyzer.

[0090] (6) Number average molecular weight test: Use chloroform or tetrahydrofuran as the mobile phase, the elution rate is 0.8 mL / min, the injection temperature is 40°C, and the standard sample is polystyrene.

[0091] Example 1

[0092] (1) 0.4 mol (24.8 g) of 1,2-ethylene glycol and 0.2 mol (51.6 g) of 4,4-diphenyl ether dicarboxylic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the mixture was stirred at a constant temperature for 4 hours for esterification; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump. The polycondensation stage was carried out, the temperature was raised to 240°C, the system vacuum was 25-30 Pa, and the reaction was continued for 0.1 hour. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol I.

[0093] (2) 0.22 mol (13.64 g) of 1,2-ethylene glycol and 0.2 mol (23.6 g) of succinic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the mixture was stirred at a constant temperature for 4 hours for esterification; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump. The polycondensation stage was carried out, the temperature was raised to 220°C, the system vacuum was 25-30 Pa, and the reaction was continued for 0.1 hour. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol II.

[0094] (3) 2 g of the prepolymer diol I and 18 g of the prepolymer diol II prepared above, 1.76 g of hexamethylene diisocyanate, and 0.1 g of stannous octoate catalyst were added to a three-necked flask and reacted at 140° C. for 2 h under N2 protection to obtain polyester.

[0095] Figure 1 The H NMR spectrum of the polyester prepared in Example 1 is as follows: Figure 1It can be seen that the polyester contains the structure of polybutylene succinate, δ = 4.38 ppm (1) corresponds to the chemical shift of H on the carbon close to the oxygen atom of polybutylene succinate, δ = 1.86 ppm (2) corresponds to the chemical shift of H on the two middle carbons of polybutylene succinate, δ = 2.62 ppm (3) corresponds to the chemical shift of H on the methylene carbon of succinic acid in polybutylene succinate; on polybutylene diphenyl ether dicarboxylate, δ = 4.14 ppm m(4) ​​corresponds to the chemical shift of H on the carbon closest to the oxygen atom in butanediol diphenyl ether dicarboxylate, δ=1.75ppm(5) corresponds to the chemical shift of H on the two middle carbons in butanediol diphenyl ether dicarboxylate, δ=7.08pp(6) corresponds to the chemical shift of H on the carbon closest to the ether bond in butanediol diphenyl ether dicarboxylate, and δ=8.09ppm(7) corresponds to the chemical shift of H on the benzene ring of diphenyl ether dicarboxylic acid close to the carbonyl carbon in butanediol diphenyl ether dicarboxylate.

[0096] Example 2

[0097] (1) 0.4 mol (24.8 g) of 1,2-ethylene glycol and 0.2 mol (51.6 g) of 3,3-diphenyl ether dicarboxylic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the mixture was stirred at a constant temperature for 4 hours for esterification; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump. The polycondensation stage was carried out, the temperature was raised to 240°C, the system vacuum was 25-30 Pa, and the reaction was continued for 0.3 hours. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol I.

[0098] (2) 0.24 mol (14.88 g) of 1,2-ethylene glycol and 0.2 mol (62.8 g) of octadecanedioic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the mixture was stirred at a constant temperature for 4 hours for esterification; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump. The polycondensation stage was carried out, the temperature was raised to 220°C, the system vacuum degree was 25-30 Pa, and the reaction was continued for 0.3 hours. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol II.

[0099] (3) 4 g of the prepolymer diol I and 16 g of the prepolymer diol II prepared above, 0.61 g of toluene diisocyanate, and 0.1 g of stannous octoate catalyst were added to a three-necked flask and reacted at 130° C. for 2 h under N2 protection to obtain polyester.

[0100] Example 3

[0101] (1) 0.4 mol (36 g) of 1,4-butanediol and 0.2 mol (51.6 g) of 4,4-diphenyl ether dicarboxylic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the mixture was stirred at a constant temperature for 3 hours for esterification; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump. The polycondensation stage was carried out, the temperature was raised to 220°C, the system vacuum was 25-30 Pa, and the reaction was continued for 0.1 hour. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol I.

[0102] (2) 0.22 mol (19.8 g) of 1,4-butanediol and 0.2 mol (23.6 g) of succinic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condenser was opened, N2 was introduced, and the temperature was raised to 160°C. After the monomers were completely melted, the esterification reaction was carried out by constant temperature stirring for 4 hours; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump. The polycondensation stage was carried out, the temperature was raised to 220°C, the system vacuum degree was 25-30 Pa, and the reaction was continued for 0.1 hour. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol II.

[0103] (3) 6 g of the prepolymer diol I and 14 g of the prepolymer diol II prepared above, 2.75 g of diphenylmethane diisocyanate, and 0.1 g of stannous octoate catalyst were added to a three-necked flask and reacted at 150° C. for 2 h under N2 protection to obtain polyester.

[0104] Example 4

[0105] (1) 0.3 mol (31.2 g) of 1,5-pentanediol and 0.2 mol (51.6 g) of 3,3-diphenyl ether dicarboxylic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 160°C. After the monomers were completely melted, the esterification reaction was carried out by constant temperature stirring for 4 hours to complete the esterification reaction stage; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump to carry out the polycondensation stage. The temperature was raised to 240°C, the system vacuum degree was 25-30 Pa, and the reaction was continued for 0.1 hour. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol I.

[0106] (2) 0.22 mol (22.88 g) of 1,5-pentanediol and 0.2 mol (23.6 g) of succinic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the esterification reaction was carried out by constant temperature stirring for 4 hours to complete the esterification reaction stage; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump to carry out the polycondensation stage. The temperature was raised to 220°C, the system vacuum degree was 25-30 Pa, and the reaction was continued for 0.1 hour. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol II.

[0107] (3) 6 g of the prepolymer diol I and 14 g of the prepolymer diol II prepared above, 2.75 g of diphenylmethane diisocyanate, and 0.1 g of stannous octoate catalyst were added to a three-necked flask and reacted at 130° C. for 4 h under N2 protection to obtain polyester.

[0108] Example 5

[0109] (1) 0.3 mol (31.2 g) of 1,5-pentanediol and 0.2 mol (51.6 g) of 4,4-diphenyl ether dicarboxylic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the esterification reaction was carried out by constant temperature stirring for 4 hours to complete the esterification reaction stage; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McIver vacuum gauge, and an oil pump to carry out the polycondensation stage. The temperature was raised to 220°C, the system vacuum degree was 25-30 Pa, and the reaction was continued for 0.3 hours. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol I.

[0110] (2) 0.24 mol (24.96 g) of 1,5-pentanediol and 0.2 mol (62.8 g) of octadecanoic acid were added to a 250 mL three-necked flask equipped with a stirring device, a condensing device, and a nitrogen protection device; 0.34 g of tetrabutyl titanate catalyst was added dropwise to the three-necked flask. The condensing water was opened, N2 was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the esterification reaction was carried out by constant temperature stirring for 4 hours to complete the esterification reaction stage; then the condensing device was removed and replaced with a vacuum device equipped with a safety bottle, a McLaurel vacuum gauge, and an oil pump to carry out the polycondensation stage. The temperature was raised to 220°C, the system vacuum degree was 25-30 Pa, and the reaction was continued for 0.3 hours. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain the purified prepolymer diol II.

[0111] (3) 8 g of the prepolymer diol I and 12 g of the prepolymer diol II prepared above, 0.96 g of dicyclohexylmethane diisocyanate, and 0.1 g of stannous octoate catalyst were added to a three-necked flask and reacted at 150° C. for 2 h under N2 protection to obtain polyester.

[0112] Example 6

[0113] Polyester was prepared according to the method of Example 5, except that the reaction time in the polycondensation stage of steps (1) and (2) was 0.08 h, and the number average molecular weights of the prepared prepolymer diol I and prepolymer diol II were both less than 2000 g / mol. In step (3), 8 g of the above-prepared prepolymer diol I and 12 g of prepolymer diol II, 3.85 g of dicyclohexylmethane diisocyanate, and 0.1 g of stannous octoate catalyst were added to a three-necked flask and reacted at 150° C. for 2 h under N2 protection to obtain polyester.

[0114] Comparative Example 1

[0115] 1 mol (90 g) of 1,4-butanediol, 0.35 mol (31.5 g) of succinic acid, and 0.15 mol (38.7 g) of diphenyl ether dicarboxylic acid were added to a 250 mL three-necked flask equipped with a stirrer, condenser, and nitrogen atmosphere. 0.85 g of tetrabutyl titanate catalyst was added dropwise to the flask. The condenser was opened, nitrogen was introduced, and the temperature was raised to 180°C. After the monomers were completely melted, the esterification reaction was continued with constant stirring for 4 hours. The condenser was then removed and replaced with a vacuum pump equipped with a safety bottle, McIver vacuum gauge, and oil pump. The polycondensation stage was carried out, with the temperature raised to 220°C and the reaction continued for 3 hours. The system vacuum was maintained at 25-30 Pa. The product was collected at room temperature, dissolved in chloroform, precipitated with methanol, and filtered and dried to obtain purified polyester.

[0116] Comparative Example 2

[0117] Polyester was prepared according to the method described in Example 1, except that in step (3), the amount of prepolymer diol I added was 1 g, and the amount of prepolymer diol II added was 19 g.

[0118] Comparative Example 3

[0119] Polyester was prepared according to the method described in Example 5, except that in step (3), the amount of prepolymer diol I added was 10 g, and the amount of prepolymer diol II added was 10 g.

[0120] Figure 2 The DSC curves of the polyesters prepared in Example 3 and Comparative Example 1 are shown in FIG. Figure 2 It can be seen from the figure that an obvious endothermic melting peak appears at 113 °C, which corresponds to the melting point of polybutylene succinate (T m The exothermic peak of the cooling DSC curve at 73°C is attributed to the crystallization of polybutylene succinate (T c Since poly(butylene diphenyl ether dicarboxylate) is in a non-crystallizing amorphous state, the polyester only exhibits the melting and crystallization of poly(butylene succinate). The DSC curve of Comparative Example 1 shows that the random copolyester is amorphous. This is because the 4,4'-butylene diphenyl ether dicarboxylate in the chain segment destroys the regularity of butylene succinate, making the polyester non-crystalline. The difference in thermal performance between Example 3 and Comparative Example 1 stems from the difference in block sequence and random sequence structure in the molecular chain segment.

[0121] from Figure 3 As can be seen in the stress-strain curves of the polyesters obtained in Example 3 and Comparative Example 1, Example 3 has a tensile strength of 11.5 MPa and an elongation at break of 770%. Comparative Example 1 has a tensile strength of 7.9 MPa and an elongation at break of 850%. Example 3 and Comparative Example 1 have the same chemical monomer molar ratio, but the structure of Example 3 forms polybutylene succinate crystals, exhibiting higher tensile strength. However, both polyesters have an elongation at break greater than 700%, demonstrating good toughness.

[0122] from Figure 4 and Figure 5 It can be seen that the strengths of the first and tenth cycles of Example 3 at 200% strain are σ1=1.8MPa and σ 10 =1.35MPa, recovery rate (σ 10 / σ1) reaches 75%; the corresponding strengths of the first and tenth cycles of Comparative Example 1 at 200% strain are σ1 = 0.79 MPa and σ 10 =0.37MPa, recovery rate (σ 10 / σ1) is only 45%, that is, Example 3 has higher rebound resilience than Comparative Example 1. This is because the structure in Example 3 allows the poly (butylene 4,4'-diphenyl ether dicarboxylate) block and the poly (butylene succinate) block to form an effective sea-island structure, which is conducive to improving its rebound resilience.

[0123] Test Example 1

[0124] The physical and chemical parameters of the block polyesters prepared in the above examples and comparative examples were tested, and the obtained parameters are shown in Table 1 and Table 2:

[0125] Table 1

[0126]

[0127]

[0128] Table 2

[0129]

[0130] From the comparison between the examples and comparative examples 2-3, it can be seen that when structures A, B, and C are simultaneously present, controlling the content of structure A to 10-40 wt% can effectively improve the multiple stretch recovery rate (elasticity) and biodegradability. However, when the content of structure A is too low (less than 10 wt%), the physical crosslinking points of the resulting polyester are too low, resulting in a poor rebound effect; when the content of structure A is too high (greater than 40 wt%), the corresponding physical crosslinking points are too high, resulting in a low elastic deformation. In other words, it is difficult to achieve high elasticity properties when the content of structure A is too high or too low.

[0131] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A block polyester, characterized in that The block polyester contains structure A, structure B and structure C, and in the block polyester, the mass ratio of the structure A to the structure B is 1:1.5-9; The structure A is shown in formula (I): The structure B is shown in formula (II): The structure C is shown in formula (III): Wherein, R1 and R2 are each independently a C2-C5 alkylene group, R3 is a C4-C18 alkylene group, and R4 is a hydrocarbon residue of a diisocyanate.

2. The block polyester according to claim 1, characterized in that The block polyester has a structural formula as shown in formula (IV): Preferably, n is 6-21, and m is 5-41.

3. The block polyester according to claim 1, characterized in that In the block polyester, the mass ratio of structure A to structure B is 1:2.3-4; Preferably, R4 is a C4-C8 chain alkylene group, a C10-C15 cyclic alkylene group, a divalent phenyl group, a methyl-substituted divalent phenyl group, or a divalent aralkyl group containing two benzene rings.

4. The block polyester according to any one of claims 1 to 3, characterized in that The block polyester has a recovery rate greater than or equal to 65% after cyclic stretching 10 times, and a degradation rate greater than or equal to 70% after composting at a thickness of 0.2 mm for 7 months; Preferably, the block polyester has a recovery rate of 75-80% after cyclic stretching 10 times, and a degradation rate of greater than or equal to 70% after composting at a thickness of 0.2 mm for 6 months.

5. The block polyester according to any one of claims 1 to 3, characterized in that The block polyester has a tensile strength of 10-30 MPa and an elongation at break of 550-1000%.

6. A method for preparing a block polyester, characterized in that: The steps include: (1) mixing monomer a represented by formula (V), monomer b represented by formula (VI) and a catalyst, and then subjecting them to an esterification reaction and then a polycondensation reaction to obtain a prepolymer diol I having a structure of formula (I); The monomer c represented by formula (VII), the monomer d represented by formula (VIII) and the catalyst are mixed and first subjected to esterification reaction and then polycondensation reaction to obtain a prepolymer diol II with the structure of formula (II); wherein R1 and R2 are each independently a C2-C5 alkylene group, R3 is a C4-C18 alkylene group, and R5, R6, R7 and R8 are each independently a methyl group or hydrogen; (2) reacting the prepolymer diol I, the prepolymer diol II, a diisocyanate and a catalyst under chain extension reaction conditions, wherein the mass ratio of the prepolymer diol I to the prepolymer diol II is 1:1.5-9.

7. The preparation method according to claim 6, characterized in that In step (1), R5, R6, R7 and R8 are each independently methyl or hydrogen; Preferably, the monomer b is selected from at least one of 3,3'-diphenyl ether dicarboxylic acid, 3,3'-diphenyl ether dicarboxylic acid dimethyl ester, 4,4'-diphenyl ether dicarboxylic acid and 4,4'-diphenyl ether dicarboxylic acid dimethyl ester; the catalyst is an organic titanium catalyst; Preferably, the organic titanium catalyst is tetrabutyl titanate and / or tetraethyl titanate; Preferably, the molar ratio of the monomer a to the monomer b is 1.5-2:1, and the molar ratio of the monomer c to the monomer d is 1.1-1.2:

1.

8. The preparation method according to claim 6 or 7, characterized in that In step (1), the number average molecular weight of the prepolymer diol I is 2000-6000 g / mol, and the number average molecular weight of the prepolymer diol II is 2000-6000 g / mol; Preferably, the glass transition temperature of the prepolymer diol I is greater than 40°C.

9. The preparation method according to claim 6 or 7, characterized in that: In step (2), the diisocyanate is selected from at least one of hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, and dicyclohexylmethane diisocyanate; and the catalyst is an organotin catalyst; Preferably, the organotin catalyst is stannous octoate and / or dibutyltin dilaurate; Preferably, the molar ratio of the sum of the moles of the prepolymer diol I and the prepolymer diol II to the diisocyanate is 1:1.05-1.1; Preferably, the added amount of the catalyst is 0.005-0.008 g relative to 1 g of diisocyanate.

10. Use of the block polyester according to any one of claims 1 to 5 or the block polyester prepared according to the preparation method according to any one of claims 6 to 9 in medical elastic materials; Preferably, the medical elastic material is a disposable medical elastomer and / or a rebound strip for diapers.

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