Process for the preparation of biodegradable polybutylene succinate and polybutylene adipate block copolyesters

Abstract

The application provides a preparation method of a biodegradable polybutylene succinate and polybutylene adipate block copolymer, in which succinic acid and adipic acid are respectively esterified and pre-polycondensed to prepare a prepolymer, the prepolymer is respectively polycondensed under high vacuum conditions, and then co-polycondensation is carried out. The method solves the problems of random distribution of polymer structure, many by-products, poor thermal performance, low molecular weight and the like in the prior art, the preparation method can make the polymer have a block structure, significantly reduce the generation of side reactions and the yield of by-products, improve the thermal performance and mechanical performance of the polymer, and a block polymer with excellent performance and high molecular weight is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular material synthesis, and particularly relates to a preparation method of biodegradable polybutylene succinate and polybutylene adipate block copolymer. BACKGROUND

[0002] With the continuous development of science and technology, high molecular materials are gradually applied to various fields in daily life. Biodegradable high molecular materials are widely concerned by the academic and industrial circles due to their environmental friendliness and biomedical applications. Among biodegradable polyesters, polybutylene succinate (PBS) has become one of the fastest growing polyester varieties due to its excellent comprehensive performance and good industrial prospects.

[0003] PBS can be decomposed or degraded into carbon dioxide and water by most microorganisms and enzymes in the bodies of animals and plants in nature, and has a wide application prospect. Compared with other aliphatic polyesters, PBS not only has a higher melting point (compared with low-density polyethylene), but also has a higher tensile strength and hardness (generally between polyethylene and polypropylene). In addition, PBS has a strength and toughness comparable to low-density polyethylene. However, compared with other widely used aromatic polyester materials, aliphatic polyester PBS still has obvious defects. In terms of performance, PBS has poor melt strength and impact strength, and it is difficult to obtain high molecular weight polyester; in terms of economy, the use of succinic acid raw material for synthesizing PBS material is expensive, which reduces the economic benefit of the product.

[0004] Poly (butylene succinate-co-adipate) (PBSA) is an aliphatic copolyester prepared by direct esterification or transesterification from adipic acid, succinic acid and 1,4-butanediol. In the copolymerization process, the introduction of adipic acid structural unit destroys the crystal lattice structure of PBS itself, thereby improving the defects of large brittleness and weak impact strength of PBS material. Compared with PBS, the molecular weight of PBSA increases, the melt viscosity increases, and the processing performance of the product is more excellent. At the same time, the introduction of low-cost adipic acid as a copolymer unit replaces part of succinic acid, thereby reducing the production cost and expanding the economic benefit.

[0005] At present, the method for synthesizing PBSA still has defects. First, in the process of using a catalyst to catalyze adipic acid, succinic acid and 1,4-butanediol to prepare PBSA, 1,4-butanediol undergoes a cyclization reaction to generate tetrahydrofuran, which adversely affects the further improvement of the molecular weight of the product and reduces the yield of the product. Second, the PBSA obtained by the current preparation process is a random copolymer, which has defects such as low melting point, poor thermal performance and low molecular weight, which seriously limits the wide application of PBSA.

[0006] Patent CN106366296A improves the preparation process of PBSA by using succinic anhydride instead of succinic acid. The product is obtained by using titanium catalyst to catalyze the ring-opening polymerization of succinic anhydride, adipic acid and 1,4-butanediol, and then performing vacuum polycondensation under reduced pressure. This method reduces the generation of by-products, and the acidity of succinic anhydride is much lower than that of succinic acid, thereby reducing the damage to the equipment and the maintenance cost. Patent CN103772683A solves the mutual solubility problem of titanium compounds and succinic acid. Patent CN106867207B provides a method for preparing PBSA with good color value. However, the above patents are all random copolymers, and the melting point of the polymer is low. Moreover, the problems of excessive by-products, low molecular weight of the product and poor thermal performance are not solved. SUMMARY

[0007] To solve the problems existing in the prior art, the present application provides a preparation method of polybutylene succinate and polybutylene adipate block copolymer. The prepared polymer has a block structure, significantly reduces the generation of side reactions and the yield of by-products, effectively improves the thermal performance and mechanical properties of the polymer, and obtains a block polymer with excellent performance and high molecular weight.

[0008] A preparation method of a biodegradable polybutylene succinate and polybutylene adipate block copolymer, comprising the following steps:

[0009] S1-1, mixing a dibasic acid monomer and a dibasic alcohol, and then performing normal pressure esterification to obtain an ester reaction product a; the dibasic acid monomer is adipic acid and / or adipic acid dimethyl ester.

[0010] S1-2, pre-polycondensation of the ester reaction product a under vacuum to obtain a pre-polycondensation product A.

[0011] S1-3, polycondensation of the pre-polycondensation product A under high vacuum to obtain a prepolymer C.

[0012] S2-1, mixing a dibasic acid monomer and a dibasic alcohol, and then performing normal pressure esterification to obtain an ester reaction product b; the dibasic acid monomer is succinic acid and / or succinic acid dimethyl ester.

[0013] S2-2, pre-polycondensation of the ester reaction product b under vacuum to obtain a pre-polycondensation product B.

[0014] S2-3, polycondensation of the pre-polymer B under high vacuum to obtain a prepolymer D.

[0015] S3, mixing the prepolymers C and D with a polycondensation catalyst, and then performing polycondensation to obtain a biodegradable polybutylene succinate and polybutylene adipate block copolymer.

[0016] Preferably, in steps S1-S3, the dihydric alcohol is 1,4-butanediol.

[0017] Preferably, in steps S1-1 and S2-1, the molar ratio of diacid monomer to dihydric alcohol is 1:1.1-3.

[0018] Preferably, in step S3, in the diacid monomer, the molar percentage of succinic acid and / or dimethyl succinate is not less than 30%, preferably 30-90 mol%; the molar percentage of adipic acid and / or dimethyl adipate is not more than 70%, preferably 10-70 mol%.

[0019] Preferably, in steps S1-1 and S2-1, during the atmospheric esterification reaction, the reaction temperature is 150-200℃, and the reaction time is 2-6h.

[0020] Preferably, in steps S1-1 and S2-1, the atmospheric esterification reaction is carried out under the combined action of an esterification catalyst and a thermal stabilizer. The mass of the esterification catalyst added is 0.001-1% of the sum of the mass of the diacid monomer and the dihydric alcohol, and the mass of the thermal stabilizer added is 0.001-1% of the sum of the mass of the diacid monomer and the dihydric alcohol.

[0021] Preferably, in steps S1-1 and S2-1, the esterification catalyst is selected from one or more of antimony trioxide, zinc acetate, antimony acetate, titanium tetra-n-butyl ester, titanium isopropyl ester, and dibutyl tin oxide. The thermal stabilizer is selected from one or more of triphenyl phosphate, triphenyl phosphite, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, and magnesium phosphate.

[0022] Preferably, in steps S1-2 and S2-2, in the pre-polycondensation reaction, the reaction temperature is 220-240℃, the reaction pressure is 500-1000Pa, and the reaction time is 0.5-2h.

[0023] Preferably, in steps S1-2 and S2-2, the pre-polycondensation process further includes adding a catalyst and a thermal stabilizer. The mass of the catalyst added is 0.001-1% of the sum of the mass of the diacid monomer and the dihydric alcohol, the polycondensation catalyst is selected from one or more of antimony trioxide, zinc acetate, antimony acetate, titanium tetra-n-butyl ester, titanium isopropyl ester, and dibutyl tin oxide, the mass of the thermal stabilizer added is 0.001-1% of the sum of the mass of the diacid monomer and the dihydric alcohol, and the thermal stabilizer is selected from one or more of triphenyl phosphate, triphenyl phosphite, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, and magnesium phosphate.

[0024] Preferably, in step S1-3, S2-3, the reaction pressure is 50-200 Pa, and the reaction time is 0.5-2 h.

[0025] Preferably, in step S1-3, S2-3, the molecular weight of the prepolymer C is in the range of 4000-10000 g / mol, the molecular weight of the prepolymer D is in the range of 2000-10000 g / mol, and at least one of the two has a molecular weight greater than 5000 g / mol during the reaction.

[0026] Preferably, in step S3, the reaction temperature during the polycondensation reaction is 220-240℃, the reaction pressure is 50-150 Pa, and the reaction time is 3-5 h.

[0027] Preferably, in step S3, the process of the polycondensation reaction further comprises adding a polycondensation catalyst and a heat stabilizer, the mass of the polycondensation catalyst added is 0.001-1% of the sum of the mass of the diacid monomer and the diol, the polycondensation catalyst is selected from one or more of antimony trioxide, zinc acetate, antimony acetate, titanium tetra-n-butyl, isopropyl titanate, and dibutyl tin oxide, the mass of the heat stabilizer added is 0.001-1% of the sum of the mass of the diacid monomer and the diol, and the heat stabilizer is selected from one or more of triphenyl phosphate, triphenyl phosphite, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, and magnesium phosphate.

[0028] The preparation method of the polybutylene succinate and polybutylene adipate block copolymer provided by the present application has a mass ratio of by-products to total amount of raw materials ≤2.5%, and the by-products are tetrahydrofuran, which effectively reduces the generation of by-products. The polybutylene succinate and polybutylene adipate block copolymer prepared has a weight average molecular weight greater than 200000, a specific viscosity ≥2.0 dL / g, a melting temperature T m1 related to the PBA block ≥60℃, a melting temperature T m2 related to the PBS block ≥106℃, a carboxyl end group content ≤10 mol / t, and a tensile breaking strength ≥20 MPa, which solves the problems of low melting point and poor thermal performance of random poly(butylene succinate-co-adipate) while increasing the molecular weight.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] 1. The present application uses dimethyl succinate instead of succinic acid as a polymerization monomer, and the mass ratio of by-products to total amount of raw materials is ≤2.5%, which reduces the generation of by-products.

[0031] 2、The prepared biodegradable block polyester has an intrinsic viscosity of 2.0 dL / g or more, a Mw of 200,000 g / mol or more, a T m1 m2 60℃, a T 6 106℃, a tensile breaking strength of 20 MPa or more, and excellent comprehensive performance.

[0032] 3、The application can be widely applied in the fields of food and medical devices, the product itself has biodegradability, does not cause environmental pollution, and can realize large-scale production, and has a wide application prospect. DETAILED DESCRIPTION

[0033] The examples described below are part of the examples of the application, but not all the examples. Based on the examples in the application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0034] The application will be further explained and described below in combination with specific embodiments.

[0035] In the following examples of the application, the raw materials used are all commercially available products, which are directly used without special treatment.

[0036] In the following examples of the application, the analysis and test methods used are described as follows:

[0037] 1. Carboxyl end group content:

[0038] The carboxyl end group content of the sample is calculated according to formula (1).

[0039] Z=(V2-V1)P·m·10 6 / (V-V0)M·m1 (1)

[0040] In the formula, Z is the carboxyl end group value of the PBSA sample, mol / t;

[0041] V2 is the volume of NaOH standard solution required for titration of the carboxyl end group, mL;

[0042] V1 is the volume of NaOH standard solution consumed for neutralization of excess HCL, mL;

[0043] P is the purity of the reference substance KHC8H4O4;

[0044] m is the mass of the reference KHC8H4O4, g;

[0045] V is the volume of NaOH standard solution consumed for titration of the reference KHC8H4O4 solution, mL;

[0046] V0 is the volume of NaOH standard solution consumed for titration of the blank solution, mL;

[0047] M is the molar mass of KHC8H4O4 (204.22 g / mol);

[0048] m1 is the mass of PBSA, g.

[0049] 2. Intrinsic viscosity:

[0050] The intrinsic viscosity of the sample is determined by using an Ubbelohde viscometer, the test temperature is 25℃, and the solvent used is a mixture of 1,1,2,2-tetrachloroethane and phenol with a mass ratio of 1:1.

[0051] 3. Weight average molecular weight:

[0052] The weight average molecular weight of the sample is determined by using a gel permeation chromatograph, the determination temperature is 45℃, the solvent is chromatographically pure chloroform, the flow rate is 1.0 ml / min, and polystyrene is used as a reference standard.

[0053] 4. Melting point (T m ):

[0054] The T m of the sample is determined by using a differential scanning calorimeter. The specific test method is as follows: 5 mg of polymer powder sample is weighed and placed in an aluminum crucible, which is then sealed and placed in the sample furnace. Under the protection of high-purity nitrogen, the temperature is raised from room temperature to 170℃ at a rate of 20℃ / min, then kept constant for 5 minutes, then cooled to -100℃ at the same rate, kept constant for 5 minutes, and then raised to 170℃ at a rate of 20℃ / min. Save all the heating and cooling curves, and record the T m1 , T m2 of the sample.

[0055] 5. Mass ratio of byproduct to total amount of raw materials:

[0056] The mass ratio of byproduct to total amount of raw materials produced in the preparation process is determined by using an Abbe refractometer. The specific test method is as follows: set the test temperature of the Abbe refractometer to 20℃, add the sample liquid to be tested to the frosted surface of the light entering prism with a dropper, rotate the prism lock handle, require the liquid to be uniform and bubble-free and fill the field of view, adjust the two mirrors to make the field of view bright, rotate the hand wheel to make the prism group rotate, and observe the bright-dark boundary line moving up and down in the telescope, at the same time rotate the Amici prism hand wheel to make the field of view have no color except black and white, when the field of view has no color and the boundary line is in the center of the crosshair, observe the value indicated on the left side of the reading mirror, measure the volume of the liquid in the collection bottle with a measuring cylinder, calculate the total mass of the raw materials, and calculate the mass ratio of THF to the total amount of raw materials according to formulas (2), (3) and (4).

[0057] η ’ = η + 0.138X v -0.0302Xv 2 (2)

[0058] m = pVX v (3)

[0059] mass ratio = m / m ’ (4)

[0060] η in formula (2) is the refractive index of the sample to be measured measured at a temperature of 20°C; ’

[0061] η is the refractive index of water at a temperature of 20°C;

[0062] X v is the volume fraction of THF;

[0063] m in formula (3) is the mass of THF, g;

[0064] p is the density of THF, g / mL;

[0065] V is the volume of the liquid to be measured in the collection bottle, mL;

[0066] X v is the volume fraction of THF;

[0067] m' in formula (4) is the total mass of the raw materials put in, g.

[0068] 6. Tensile strength:

[0069] According to the ISO 527 (2012) standard, tensile test was carried out at 25°C and a tensile rate of 50 mm / min using an Instron 1122 tensile testing machine, and the average value of 5 measurements was taken as the test result.

[0070] Example 1

[0071] The synthesis method of the copolyester PBSA specifically comprises:

[0072] ​Into a reaction kettle, adipic acid (7 mol) and 1,4-butanediol (15 mol) were added, and 0.7 wt% of tetra-n-butyl titanate based on the total mass of the added adipic acid and 1,4-butanediol and 0.7 wt% of triphenyl phosphate based on the total mass of the added adipic acid and 1,4-butanediol were added. Atmospheric esterification was performed under nitrogen protection at 190°C for 3.5 h, and esterification product butanediol adipate was obtained. Then, 1 wt% of tetra-n-butyl titanate based on the total mass of the added adipic acid and 1,4-butanediol and 1 wt% of triphenyl phosphate based on the total mass of the added adipic acid and 1,4-butanediol were added. The temperature was raised to 225°C within 30 min, and the pressure was reduced to 500 Pa for pre-polycondensation for 1 h. Then, the reaction pressure was reduced to 100 Pa, and the temperature was kept constant for 1 h. After that, the product was discharged, granulated, and dried to obtain polybutanediol adipate with a molecular weight of 5000 g / mol.

[0073] Into a reaction kettle, dimethyl succinate (3 mol) and 1,4-butanediol (7 mol) were added, and 0.7 wt% of tetra-n-butyl titanate based on the total mass of the added dimethyl succinate and 1,4-butanediol and 0.7 wt% of triphenyl phosphate based on the total mass of the added dimethyl succinate and 1,4-butanediol were added. Atmospheric esterification was performed under nitrogen protection at 170°C for 3.5 h, and esterification product butanediol succinate was obtained. Then, 1 wt% of tetra-n-butyl titanate based on the total mass of the added dimethyl succinate and 1,4-butanediol and 1 wt% of triphenyl phosphate based on the total mass of the added dimethyl succinate and 1,4-butanediol were added. The temperature was raised to 225°C within 30 min, and the pressure was reduced to 700 Pa for pre-polycondensation for 1 h. Then, the reaction pressure was reduced to 150 Pa, and the temperature was kept constant for 1 h. After that, the product was discharged, crushed, and dried to obtain polybutanediol succinate with a molecular weight of 4200 g / mol.

[0074] Into a reaction kettle, the obtained polybutanediol adipate and polybutanediol succinate (molar ratio of adipic acid units to dimethyl succinate units was 1:1, and the adipic acid units accounted for 50 mol% of the diacid) were added, and 1 wt% of tetra-n-butyl titanate based on the total mass of the added polybutanediol adipate and polybutanediol succinate and 1 wt% of triphenyl phosphate based on the total mass of the added polybutanediol adipate and polybutanediol succinate were added. The temperature was raised to 240°C within 30 min, and the pressure was reduced to 50 Pa for constant-temperature reaction for 3 h. Then, the product was discharged, granulated, and dried to obtain polymer PBSA1.

[0075] Example 2

[0076] Example 2 was tested in 6 tests, i.e., test 2.1, test 2.2, test 2.3, test 2.4, test 2.5, and test 2.6.

[0077] Test 2.1 differs from Example 1 only in that the molar ratio of adipic acid units to dimethyl succinate in the reactor before the polycondensation reaction in step S3 is 1 :9, resulting in PBSA2.

[0078] Test 2.2 differs from Example 1 only in that the molar ratio of adipic acid units to dimethyl succinate in the reactor before the polycondensation reaction in step S3 is 2:8, resulting in PBSA3.

[0079] Test 2.3 differs from Example 1 only in that the molar ratio of adipic acid units to dimethyl succinate in the reactor before the polycondensation reaction in step S3 is 3:7, resulting in PBSA4.

[0080] Test 2.4 differs from Example 1 only in that the molar ratio of adipic acid units to dimethyl succinate in the reactor before the polycondensation reaction in step S3 is 4:6, resulting in PBSA5.

[0081] Test 2.5 differs from Example 1 only in that the molar ratio of adipic acid units to dimethyl succinate in the reactor before the polycondensation reaction in step S3 is 6:4, resulting in PBSA6.

[0082] Test 2.6 differs from Example 1 only in that the molar ratio of adipic acid units to dimethyl succinate in the reactor before the polycondensation reaction in step S3 is 7:3, resulting in PBSA7.

[0083] Example 3

[0084] Example 3 was carried out in four tests, Test 3.1, Test 3.2, Test 3.3 and Test 3.4.

[0085] Test 3.1 differs from Example 2.3 in that the polycondensation time of the pre- polycondensation product of butanediol succinate is 1.5 h and the reaction pressure is 200 Pa, resulting in a polybutanediol succinate prepolymer having a molecular weight of 8000 g / mol. The polycondensation time of the pre-polycondensation product of butanediol adipate is 0.5 h and the reaction pressure is 100 Pa, resulting in a polybutanediol adipate prepolymer having a molecular weight of 4000 g / mol, resulting in PBSA8.

[0086] Test 3.2 differs from Example 2.3 in that the polycondensation time of the pre- polycondensation product of butanediol succinate is 1.2 h and the polycondensation pressure is 150 Pa, resulting in a polybutanediol succinate prepolymer having a molecular weight of 5300 g / mol. The polycondensation time of the pre-polycondensation product of butanediol adipate is 1.2 h and the reaction pressure is 50 Pa, resulting in a polybutanediol adipate prepolymer having a molecular weight of 6000 g / mol, resulting in PBSA9.

[0087] Test 3.3 differs from Example 2.3 in that the polycondensation time of the pre- polycondensation product of butylene succinate is 0.5 h, the reaction pressure is 200 Pa, and the molecular weight of the polybutylene succinate prepolymer obtained is 3200 g / mol. The polycondensation time of the pre-polycondensation product of butylene adipate is 1.5 h, the reaction pressure is 120 Pa, and the molecular weight of the polybutylene adipate prepolymer obtained is 8000 g / mol, obtaining PBSA10.

[0088] Test 3.4 differs from Example 2.3 in that the polycondensation time of the pre- polycondensation product of butylene succinate is 0.5 h, the reaction pressure is 180 Pa, and the molecular weight of the polybutylene succinate prepolymer obtained is 2000 g / mol. The polycondensation time of the pre-polycondensation product of butylene adipate is 1.5 h, the reaction pressure is 50 Pa, and the molecular weight of the polybutylene adipate prepolymer obtained is 10000 g / mol, obtaining PBSA11.

[0089] Example 4

[0090] Example 4 conducts a total of 3 tests, Test 4.1, Test 4.2 and Test 4.3.

[0091] Test 4.1 differs from Test 3.1 in that succinic acid is used instead of dimethyl succinate, and the molecular weight of the polybutylene succinate obtained is 9000 g / mol, obtaining PBSA12.

[0092] Test 4.2 differs from Test 3.2 in that dimethyl adipate is used instead of adipic acid, and the molecular weight of the polybutylene adipate obtained is 5200 g / mol, obtaining PBSA13.

[0093] Test 4.3 differs from Test 3.3 in that succinic acid is used instead of dimethyl succinate, and the molecular weight of the polybutylene succinate obtained is 4000 g / mol; dimethyl adipate is used instead of adipic acid, and the molecular weight of the polybutylene adipate obtained is 8300 g / mol, obtaining PBSA14.

[0094] Example 5

[0095] Example 5 conducts a total of 3 tests, Test 5.1, Test 5.2 and Test 5.3.

[0096] Test 5.1 differs from Example 2.2 in that the polybutylene succinate pre- polycondensation time of step S2-2 is 0.7 h, the polybutylene adipate pre-polycondensation time of step S1-2 is 0.5 h, the polycondensation reaction temperature of step S3 is 230 °C, and the polycondensation reaction pressure is 100 Pa, obtaining PBSA15.

[0097] Test 5.2 differs from Example 2.2 in that the polybutylene succinate pre- polycondensation time of step S2-2 is 0.5 h, the polybutylene adipate pre- polycondensation time of step S1-2 is 1 h, the polycondensation reaction temperature of step S3 is 220 °C, and the polycondensation reaction pressure is 80 Pa, to obtain PBSA16.

[0098] Test 5.3 differs from Example 2.2 in that the polybutylene succinate polycondensation time of step S2-2 is 1.5 h, the polybutylene adipate pre- polycondensation time of step S1-2 is 2 h, the polycondensation reaction temperature of step S3 is 225 °C, and the polycondensation reaction pressure is 150 Pa, to obtain PBSA17.

[0099] Example 6

[0100] Example 6 was subjected to Test 6.1, Test 6.2, Test 6.3, and Test 6.4, for a total of 4 tests.

[0101] Test 6.1 differs from Example 1 in that the esterification catalyst of adipic acid and 1,4-butanediol is isopropyl titanate (0.1% of the total mass of adipic acid and 1,4-butanediol is input as the catalyst), and the heat stabilizer is triphenyl phosphite (0.05% of the total mass of adipic acid and 1,4-butanediol is input as the heat stabilizer), to obtain PBSA18.

[0102] Test 6.2 differs from Example 1 in that the esterification catalyst of adipic acid and 1,4-butanediol is zinc acetate (0.01% of the total mass of adipic acid and 1,4-butanediol is input as the catalyst), and the heat stabilizer is sodium dihydrogen phosphate (0.01% of the total mass of adipic acid and 1,4-butanediol is input as the heat stabilizer), to obtain PBSA19.

[0103] Test 6.3 differs from Example 1 in that the pre-polycondensation catalyst and the polycondensation catalyst are isopropyl titanate (0.1% of the total mass of the diacid monomer and diol raw materials is input as the catalyst), and the heat stabilizer is triphenyl phosphite (0.05% of the total mass of the diacid monomer and diol raw materials is input as the heat stabilizer), to obtain PBSA20.

[0104] Test 6.4 differs from Example 1 in that the pre-polycondensation catalyst and the polycondensation catalyst are antimony trioxide (0.01% of the total mass of the diacid monomer and diol raw materials is input as the catalyst), and the heat stabilizer is potassium phosphate (0.1% of the total mass of the diacid monomer and diol raw materials is input as the heat stabilizer), to obtain PBSA21.

[0105] Comparative Example 1

[0106] Succinic acid (7 mol), adipic acid (3 mol), 1,4-butanediol (16 mol) were added into a reaction kettle, wherein the adipic acid units accounted for 30 mol% of the dibasic acid, 0.7 wt% of titanium tetrabutylate and triphenyl phosphate based on the total mass of the input raw materials were added, and normal pressure esterification was carried out under nitrogen protection at 170°C for 3.5 h. After the esterification reaction was completed, 1 wt% of titanium tetrabutylate and triphenyl phosphate based on the total mass of the input raw materials were added, and the temperature was raised to 240°C within 30 min and the pressure was reduced to 50 Pa. After 3 h of reaction, the product was discharged, pelletized, and dried to obtain the polymer PBSA22.

[0107] The performance of the PBSA product prepared according to the present application was tested, and the results are shown in Table 1.

[0108]

[0109]

[0110] As can be seen from Table 1, the polyester material prepared according to the present application not only has a very high molecular weight and good thermal and mechanical properties, but also reduces the generation of by-products, which is crucial for the application of polyester in the fields of food packaging, medical devices, films, fibers, etc.

[0111] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of a biodegradable polybutylene succinate and polybutylene adipate block copolyester, characterized in that, It comprises the following steps: S1-1, mixing binary acid monomer with binary alcohol, then carrying out normal pressure esterification reaction to obtain ester reaction product a; the binary acid monomer is adipic acid and / or adipic acid dimethyl ester; S1-2, pre-polycondensation of the esterification product a under vacuum condition to obtain pre-polycondensation product A; S1-3, polycondensation reaction of the pre-polycondensation product A under high vacuum condition to obtain prepolymer C; S2-1, mixing binary acid monomer with binary alcohol, then carrying out normal pressure esterification reaction to obtain ester reaction product b; the binary acid monomer is succinic acid and / or succinic acid dimethyl ester; S2-2, pre-polycondensation of the esterification product b under vacuum condition to obtain pre-polycondensation product B; S2-3, polycondensation reaction of the pre-polycondensation product B under high vacuum condition to obtain prepolymer D; S3, mixing prepolymers C and D with polycondensation catalyst and then carrying out polycondensation reaction to obtain biodegradable polyester polybutylene succinate and polybutylene adipate block copolymer; In steps S1-S3, the binary alcohol is 1,4-butanediol; In steps S1-1 and S2-1, the molar ratio of binary acid monomer to binary alcohol is 1:1.1-3; In steps S1-1 and S2-1, the reaction temperature during the normal pressure esterification reaction is 150-200℃, and the reaction time is 2-6 h; In steps S1-2 and S2-2, the reaction temperature during the pre-polycondensation reaction is 220-240℃, the reaction pressure is 500-1000 Pa, and the reaction time is 0.5-2 h; The polycondensation reaction pressure in S1-3 and S2-3 is 50-200 Pa, and the reaction time is 0.5-2 h; In step S3, the reaction temperature during the polycondensation reaction is 220-240℃, the reaction pressure is 50-150 Pa, and the reaction time is 3-5 h.

2. The process for the preparation of biodegradable polybutylene succinate and polybutylene adipate block copolyesters according to claim 1, characterized in that, In steps S1-1 and S2-1, the normal pressure esterification reaction is carried out under the joint action of esterification catalyst and heat stabilizer, the mass of the esterification catalyst added is 0.001-1% of the sum of the mass of binary acid monomer and binary alcohol, and the mass of the heat stabilizer added is 0.001-1% of the sum of the mass of binary acid monomer and binary alcohol.

3. Process for the preparation of biodegradable polybutylene succinate and polybutylene adipate block copolyesters according to claim 2, characterized in that, In steps S1-1 and S2-1, the esterification catalyst is selected from one or more of antimony trioxide, zinc acetate, antimony acetate, titanium tetra-n-butyl ester, titanium isopropyl ester, and dibutyl tin oxide; and the heat stabilizer is selected from one or more of triphenyl phosphate, triphenyl phosphite, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, and magnesium phosphate.

4. The process for the preparation of biodegradable polybutylene succinate and polybutylene adipate block copolyesters according to claim 1, characterized in that, In the step S1-2, S2-2, the pre-polycondensation process further comprises adding a catalyst and a thermal stabilizer; the mass of the catalyst added is 0.001-1% of the sum of the mass of the diacid monomer and the mass of the dihydric alcohol; the catalyst is selected from one or more of antimony trioxide, zinc acetate, antimony acetate, titanium tetra-n-butyl ester, isopropyl titanate, dibutyl tin oxide; the mass of the thermal stabilizer added is 0.001-1% of the sum of the mass of the diacid monomer and the mass of the dihydric alcohol; the thermal stabilizer is selected from one or more of triphenyl phosphate, triphenyl phosphite, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, magnesium phosphate.

5. The process for the preparation of biodegradable polybutylene succinate and polybutylene adipate block copolyesters according to claim 1, characterized in that, In the step S3, the mole percentage of butanedioic acid and / or dimethyl butanedioate in the diacid monomer is 30-90 mol%; the mole percentage of hexanedioic acid and / or dimethyl hexanedioate is 10-70 mol%.

6. The process for the preparation of biodegradable polybutylene succinate and polybutylene adipate block copolyesters according to claim 1, characterized in that, In the step S3, the process of the polycondensation reaction further comprises adding a polycondensation catalyst and a thermal stabilizer; the mass of the polycondensation catalyst added is 0.001-1% of the sum of the mass of the diacid monomer and the mass of the dihydric alcohol; the polycondensation catalyst is selected from one or more of antimony trioxide, zinc acetate, antimony acetate, titanium tetra-n-butyl ester, isopropyl titanate, dibutyl tin oxide; the mass of the thermal stabilizer added is 0.001-1% of the sum of the mass of the diacid monomer and the mass of the dihydric alcohol; the thermal stabilizer is selected from one or more of triphenyl phosphate, triphenyl phosphite, sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, potassium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, magnesium phosphate.

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