Block copolymer of aliphatic-aromatic copolyester and polyglycolic acid, and preparation method and application thereof

Abstract

The present application relates to modification of aliphatic-aromatic copolyester and polyglycolic acid blend, disclose a kind of aliphatic-aromatic copolyester and polyglycolic acid block copolymer and its preparation method and application, the block copolymer includes polyglycolic acid block and aliphatic-aromatic copolyester block;The block copolymer contains A-B diblock copolymer or A-B-A triblock copolymer, wherein block A is polyglycolic acid, and block B is aliphatic-aromatic copolyester.The block copolymer of the present application can improve the compatibility of PGA and aliphatic-aromatic copolyester blend when used as a compatibilizer, improve the mechanical properties of the blend, for example, can improve the toughness and tensile strength of PGA and aliphatic-aromatic copolyester blend.

Description

Technical Field

[0001] This invention relates to polymer blending modification, and more specifically, to a polymer containing aliphatic-aromatic copolyester and polyglycolic acid block copolymer, its preparation method, and its application. Background Technology

[0002] Polyglycolic acid (PGA), also known as polyglycolic acid or polyhydroxyacetic acid, is widely used in medical sutures, drug delivery systems, fracture fixation materials, tissue engineering scaffolds, and reinforcement materials due to its excellent biodegradability, biocompatibility, and high mechanical strength. Furthermore, it possesses excellent water / oxygen barrier properties, making it one of the best overall barrier materials; its water vapor barrier performance is approximately 100 times higher than that of polylactic acid (PLA) and similar to that of polyethylene (PE). However, the high crystallinity of PGA results in not only a high melting point but also poor toughness at room temperature, which significantly limits its application in a wider range of fields.

[0003] Aliphatic-aromatic copolyesters, as copolymers of aliphatic and aromatic polyesters, combine the advantages of both components. They possess the high toughness and good biodegradability of aliphatic polyesters, as well as the high strength and excellent thermal properties of aromatic polyesters. The most representative and widely used aliphatic-aromatic copolyesters are polybutylene terephthalate (PBAT) and polybutylene terephthalate (PBST). The former is a random copolymer of butylene adipate (BA) and butylene terephthalate (BT), while the latter is a random copolymer of butylene succinate (BS) and butylene terephthalate (BT). Driven by environmental policies, PBAT is now widely used in shopping bags, packaging, agricultural films, and textiles. Compared to PBAT, PBST has equally excellent thermal and mechanical properties. Furthermore, succinic acid can be obtained from bio-based raw materials through fermentation, thus synthesizing partially bio-based PBAT or PBST, which helps reduce carbon emissions.

[0004] Therefore, combining polyglycolic acid with aliphatic-aromatic copolyesters could potentially yield materials possessing excellent biodegradability, barrier properties, and mechanical strength. However, due to the poor compatibility between polyglycolic acid and aliphatic-aromatic copolyesters, direct blending yields less than ideal results, and the mechanical properties cannot be improved.

[0005] Chinese patent application CN 111647144 A (Shanghai Pujing Chemical, September 11, 2020) discloses a method for adjusting the molecular chain structure of polyglycolic acid (PGA). This method alters the molecular structure by adding functional groups (hydrophilic / hydrophobic groups such as -OH and -COOR) or chain segments (branching, copolymerization, etc.) with specific performance characteristics, thereby changing the original molecular properties of PGA. However, this is a low-temperature nitrogen-protected reaction with harsh conditions and a long reaction time (at least 50 minutes). This prolonged reaction time can lead to the thermal decomposition or degradation of PGA, forming colored or odorous byproducts.

[0006] Chinese patent application CN 112358708A (Green Silver Intelligent Technology (Shenzhen) Co., Ltd., 2021.02.12) discloses a high-starch-content biodegradable blown film modified material and its preparation method. In this method, PBAT-g-MAH and PLA-GMA are used as compatibilizers for PBAT and PGA to improve the mechanical properties of the resulting blend; however, the improvement effect still needs further enhancement.

[0007] There is a persistent need in this field to address the poor compatibility between polyglycolic acid and aliphatic-aromatic copolyesters. Therefore, further improving the compatibility between these two compounds in blends is a problem that needs to be solved. Summary of the Invention

[0008] To address the technical problem in existing technologies where polyglycolic acid (PGA) and aliphatic-aromatic copolyesters have poor compatibility, making it difficult to achieve ideal properties through direct blending and failing to effectively improve mechanical properties such as toughness, this invention provides a polymer containing a block copolymer of aliphatic-aromatic copolyester and PGA, its preparation method, and its applications. When used as a compatibilizer, this block copolymer can improve the compatibility of PGA and aliphatic-aromatic copolyester blends and enhance the mechanical properties of the blends.

[0009] One objective of this invention is to provide a block copolymer comprising polyglycolic acid blocks and aliphatic-aromatic copolyester blocks; wherein the block copolymer contains AB diblock copolymer or ABA triblock copolymer, wherein block A is polyglycolic acid and block B is aliphatic-aromatic copolyester.

[0010] The content of block A and block B has a wide range of selection. In a preferred embodiment of the present invention, the content of block A is 1%-99% by mass, preferably 65%-95% by mass, relative to the total mass of block A and block B, by mass. The content of block B is 1%-99% by mass, preferably 5%-40% by mass.

[0011] In a preferred embodiment of the present invention, block B is a copolyester formed by polycondensation of an aliphatic diacid and / or an aromatic diacid with an aliphatic diol.

[0012] In a more preferred embodiment of the present invention, the block B is a copolyester formed by condensation of at least one of α,ω-aliphatic diacid and aromatic diacid containing 2-18 main chain carbon atoms with at least one aliphatic diol.

[0013] In a further preferred embodiment of the present invention, the block B is at least one of polybutylene adipate-co-terephthalate, polyethylene adipate-co-terephthalate, polyethylene terephthalate-co-terephthalate, and polybutylene terephthalate-co-terephthalate.

[0014] In a preferred embodiment of the present invention, block B is polybutylene adipate terephthalate and / or polybutylene succinate terephthalate. In a preferred embodiment of the present invention, the weight-average molecular weight of block B is 1000-200000 g / mol, preferably 20000-100000 g / mol, and more preferably 40000-90000 g / mol. In this preferred embodiment, preparation is more convenient.

[0015] In a preferred embodiment of the present invention, the block copolymer contains copolymers with structural formulas as shown in formula (I) and / or formula (II):

[0016]

[0017] In equations (I) and (II), R1 is independently... or

[0018] Where x, y, and z are the degree of aggregation, each of which is an integer ranging from 50 to 5000, preferably from 1000 to 2000, and m and n are each of which is an integer ranging from 1 to 1000, preferably from 300 to 600.

[0019] In a preferred embodiment of the present invention, the weight-average molecular weight of the block copolymer is 20,000-200,000 g / mol, preferably 80,000-160,000 g / mol, for example, it can be 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000 g / mol, as well as any range or any value between any two numbers.

[0020] In a preferred embodiment of the present invention, the polydispersity index of the block copolymer is 1-3, preferably 1-2.

[0021] In a preferred embodiment of the present invention, the block copolymer is prepared by copolymerizing raw materials including glycolide and aliphatic-aromatic copolyester.

[0022] A second objective of this invention is to provide a method for preparing the block copolymer described above, comprising melting and blending components including a required amount of glycolide, an aliphatic-aromatic copolyester and a catalyst, followed by cooling to obtain the block copolymer.

[0023] In a preferred embodiment of the present invention, the ratio of glycolide to aliphatic-aromatic copolyester by mass is 100:1-99, preferably 100:5-40.

[0024] In a preferred embodiment of the present invention, the mass ratio of glycolide to catalyst is 100:(0.005-1), preferably 100:(0.01-0.5).

[0025] In a preferred embodiment of the present invention, the aliphatic-aromatic copolyester has a weight-average molecular weight of 1000-200000 g / mol, preferably 20000-100000 g / mol, and more preferably 40000-90000 g / mol; in a preferred embodiment of the present invention, the aliphatic-aromatic copolyester is selected from at least one of the following polymers: low molecular weight polymers obtained by alcoholysis of polybutylene terephthalate and / or polybutylene terephthalate; low molecular weight polymers obtained by alcoholysis of at least one of chain-extended modified polybutylene terephthalate, end-group modified polybutylene terephthalate, and polybutylene adipate; chain-extended modified polybutylene adipate and end-group modified polybutylene adipate.

[0026] In a preferred embodiment of the present invention, the catalyst is a salt compound corresponding to at least one of group IIA-VA metal elements and transition metal elements; preferably, the catalyst is a salt compound corresponding to at least one of Sn, Bi, Mg, Al, Ca, Fe, Mn, Ti and Zn, and more preferably a Sn salt.

[0027] In a preferred embodiment of the present invention, the temperature of the melt blending reaction is 180-250°C, preferably 210-230°C; and the reaction time is 3-20 min.

[0028] In a preferred embodiment of the present invention, the preparation process is carried out in a melt mixing device; preferably, the melt mixing device is a combination of one or more of the following: a batch reactor, a tubular reactor, a mixer, a Farrel continuous mixer, a Banbury mixer, a single-screw extruder, a multi-screw extruder, and a reciprocating single-screw extruder, preferably a mixer or a twin-screw extruder.

[0029] In a preferred embodiment of the present invention, the preparation process is carried out in an internal mixer; preferably, the mixing temperature is 180-250℃, more preferably 210-230℃, the rotation speed is 5-150 rpm, more preferably 20-80 rpm, and the reaction time is 3-15 min, more preferably 5-10 min.

[0030] In a preferred embodiment of the present invention, the preparation process is carried out in a twin-screw extruder; preferably, the processing temperature is 180-250℃, more preferably 210-230℃, the screw speed is 5-300rpm, more preferably 30-100rpm, and the length-to-diameter ratio is 30-80, more preferably 40-70.

[0031] The internal mixers applicable to this invention include internal mixers of various designs, such as the PolyLab HAAKE manufactured by Thermo Fisher Scientific in the United States. TM Rheomex OS 567-1000 internal mixer module, etc. Continuous twin-screw extrusion equipment applicable to this invention includes twin-screw extruders of different designs, such as co-rotating parallel twin-screw extruders like the ZSK Mcc18 or ZSK 40 manufactured by Coperion in Germany.

[0032] A third objective of this invention is to provide a block copolymer prepared by the preparation method described above.

[0033] The fourth objective of this invention is to provide an application of the block copolymer described above as a compatibilizer in injection-molded products of aliphatic-aromatic copolyesters and polyglycolic acid blends.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) The present invention directly uses polybutylene terephthalate as an initiator to initiate the ring-opening polymerization of glycolide, and directly prepares aliphatic-aromatic copolyester and polyglycolic acid block copolymer in one step, which is simpler to prepare.

[0036] (2) Compared with the traditional polyglycolic acid preparation method, this method has more relaxed reaction conditions, can be prepared under normal pressure without nitrogen protection, and has a shorter reaction time, and can achieve continuous preparation.

[0037] (3) In the application of the block copolymer of the present invention as a compatibilizer, the aliphatic-aromatic copolyester block can ensure a certain length of chain segment, which can improve the compatibility of PGA and aliphatic-aromatic copolyester blends, and at the same time improve the mechanical properties of the blends, for example, can improve the toughness and tensile strength of PGA and aliphatic-aromatic copolyester blends. Attached Figure Description

[0038] Figure 1 The strong peaks at 2.5 ppm and 3.3 ppm are absorption peaks of the solvent DMSO. The methylene proton absorption peak of PGA is at -5.0 ppm, and multiple peaks appear after block copolymerization, with the main peak shifting to a higher field by 0.1-0.2 ppm. The absorption peaks at 1.5-2.0 ppm and 4.0-4.5 ppm are proton absorption peaks of hydrogen atoms on the alkane in PBST, while the absorption peak at 8.0 ppm corresponds to hydrogen atoms on the benzene ring in PBST. Therefore, the product in Example 2 still contains PBST components after purification (the product in Example 6), indicating that PGA and PBST in Example 2 are chemically bonded, rather than physically blended.

[0039] Figure 2 These are the infrared characterization curves of pure PBST and pure PGA in Example 6 and Comparative Example 3; Figure 2 The absorption peak around 1750 cm⁻¹ is for the carbonyl group in PGA, while the absorption peak for the carbonyl group in PBST is around 1715 cm⁻¹. -1 The results showed that the two absorption peaks appeared simultaneously in Example 6, which is consistent with the results of the 1H NMR spectrum, confirming that the material in Example 6 is a block copolymer rather than a physical blend.

[0040] Figure 3 These are the DSC characterization curves of Example 6 and Comparative Example 2; by Figure 3 It can be seen that the melting point and crystallization temperature of Example 6 are slightly lower than those of Comparative Example 2, and the distance between the two glass transition temperatures of Example 6 is smaller than that of Comparative Example 2.

[0041] Figure 4 and Figure 5 The images shown are scanning electron microscope (SEM) images of the fracture surfaces of the cryogenic brittle fracture in liquid nitrogen in Example 5 and Comparative Example 1 (magnification: 1.00 kx); for comparison. Figure 4 and Figure 5 As can be seen, Example 5 (corresponding to) Figure 4 The cross-section of Example 5 is significantly smoother and more uniform than that of Comparative Example 1, indicating that the compatibility between the PGA phase and PBST in Example 5 is better than that in Comparative Example 1. Figure 5 The uneven surface and partial porosity further indicate that PGA and aliphatic-aromatic copolyester (PBXT) have poor mechanical blending properties, making the addition of a compatibilizer essential. Figure 4 , 5Comparison shows that, in this invention, the compatibilizer PGA phase and PBXT (PBAT or PBST) phase, after being linked by covalent bonds, can not only improve the compatibility of the two phases themselves, but also be added to the PGA and PBXT blend as a compatibilizer to improve the compatibility of the two phases in the blend, thereby improving the mechanical properties of the blend. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0043] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0044] Raw material source:

[0045] All raw materials used in this invention are commercially available.

[0046] Glycolide (GA), Shandong Jinan Daigang Biotechnology Co., Ltd., purity ≥99.5%.

[0047] Anhydrous stannous chloride (SnCl2), zinc acetate (dihydrate), ethylene glycol, and dodecyl alcohol were purchased from Sinopharm Chemical Reagent Co., Ltd. Anhydrous stannous chloride, zinc acetate (dihydrate), and ethylene glycol were all AR grade, while dodecyl alcohol was CP grade. Chain extender ADR (… ADR-4468 (epoxy equivalent: 310 g / mol) was purchased from BASF (China) Co., Ltd.

[0048] Polybutylene terephthalate (PBST), manufactured by Sinopec Yizheng Chemical Fiber Co., Ltd., grade TS159. Polyglycolic acid (PGA), purchased from KEBIN-Prak AB, Netherlands, is a GMP-grade homopolymer of glycolide with an average intrinsic viscosity of 1.2 dl / g.

[0049] The performance of this invention was determined according to the following method:

[0050] 1H NMR (1H NMR) spectrum 1 H-NMR: The tests were performed on a JNM-ECZ500R / S1 nuclear magnetic resonance spectrometer manufactured by JEOL Ltd., Japan. Tetramethylsilane (TMS) was used as an internal standard, and deuterated DMSO was used as the solvent.

[0051] Fourier Transform Infrared Spectroscopy (FTIR): The instrument used was a Frontier Fourier Transform Infrared Spectrometer from PerkinElmer, USA. Absorption signals were obtained using an Attenuated Total Refractive Index (ATR) accessory, with each sample ranging from 650 to 4000 cm⁻¹. -1 Scan the area 4 times.

[0052] Gel permeation chromatography (GPC): The test was performed on an Anglienti PL-GPC50 gel permeation chromatograph (USA), and the processing software was GPC offline. During the test, the mobile phase was hexafluoroisopropanol containing 5 mmol / L sodium trifluoroacetate, the flow rate was 1 mL / min, the column temperature was 40℃, the injection volume was 100 μL, the standard was PMMA, and the sample concentration was 1 mg / mL.

[0053] Differential Scanning Calorimetry (DSC): The test instrument was a Discovery series scanning calorimeter from TA Instruments (USA). During the test, 5-10 mg of sample was weighed into the sample pan. The test temperature range was 0℃-240℃. All samples underwent a heating process to eliminate thermal history, and their cooling curves were recorded simultaneously. The heating and cooling rates were 10℃ / min, and the plateau time at the highest and lowest temperatures was 2 min. The test atmosphere was nitrogen.

[0054] Scanning electron microscope (SEM) images of the cross section: After the injection-molded stretched specimen was completely immersed in liquid nitrogen and cooled, it underwent low-temperature brittle fracture. After gold sputtering, the cross section was photographed using a Merlin field emission scanning electron microscope from Zeiss GmbH, Germany.

[0055]

Example 1

[0056] Glycolide (GA), anhydrous stannous chloride, and polybutylene terephthalate succinate (PBST) (weight average molecular weight 60000 g / mol) were thoroughly premixed at a mass ratio of 80:0.024:20 using PolyLab HAAKE from Thermo Fisher Scientific, USA. TM The polymerization reaction was carried out using a Rheomex OS 567-1000 internal mixer (rotor diameter 35mm, rotor length 50mm). The rotation speed was 50 rpm, the temperature was 215℃, and the reaction time was 5 min. After the reaction, the mixture was directly cooled in air to obtain the PGA / PBST block copolymer.

[0057]

Example 2

[0058] According to Example 1, except that the ratio of glycolide (GA), anhydrous stannous chloride and polybutylene terephthalate (PBST) was changed to 70:0.021:30 to obtain PGA / PBST block copolymer.

[0059]

Example 3

[0060] According to Example 1, except that polybutylene terephthalate succinate (PBST) was replaced with polybutylene adipate terephthalate (PBAT) (weight average molecular weight is 40,000), thus obtaining a PGA / PBAT block copolymer.

[0061]

Example 4

[0062] The difference from Example 3 is that PBAT was replaced with chain-extended PBAT (weight-average molecular weight of 50,000 g / mol) to obtain PGA / PBAT block copolymer.

[0063] The general preparation process of chain-extended modified PBAT is as follows: PBAT and chain extender ADR-4368 are mixed in a ratio of 1000:3 and then extruded and granulated using a Labtech parallel co-rotating twin-screw extruder (screw diameter: 16mm, length-to-diameter ratio: 40). This extruder has 11 sections from the feed inlet to the die, numbered 1-11. Section 1 only serves as the feeding section and cannot be heated. The temperatures of sections 2-11 of the extruder are 110℃, 160℃, 210℃, 220℃, 220℃, 220℃, 220℃, 220℃, and 210℃, respectively.

[0064]

Example 5

[0065] According to Example 4, the difference is that PBAT was replaced with α,ω-dihydroxy PBAT (weight average molecular weight is 20000 g / mol) obtained by alcoholysis reaction, resulting in PGA-PBAT-PGA terblock copolymer.

[0066] The general preparation process of PBAT by alcoholysis is as follows: PBAT, zinc acetate, and ethylene glycol are mixed in a ratio of 1000:4:50 and then extruded and granulated using a Labtech parallel co-rotating twin-screw extruder (screw diameter: 16 mm, length-to-diameter ratio: 40). This extruder has 11 sections from the feed inlet to the die, numbered 1-11. Section 1 only serves as the feeding section and cannot be heated. The temperatures of sections 2-11 of the extruder are 110℃, 150℃, 190℃, 190℃, 190℃, 190℃, 190℃, 190℃, and 190℃, respectively.

[0067]

Example 6

[0068] The product obtained in Example 2 was dissolved in hexafluoroisopropanol, precipitated with a large amount of chloroform, washed, and then centrifuged and vacuum dried to remove the solvent, resulting in the purified PGA-PBST block copolymer.

[0069] Example 6 was used to verify that the product in Example 1 was a block copolymer.

[0070] Comparative Example 1

[0071] The synthesis method was similar to that of Example 1, except that the initiator in Example 1 was changed from polybutylene terephthalate (PBST) to dodecyl alcohol, and the ratio of glycolide (GA), anhydrous stannous chloride, and dodecyl alcohol was 80:0.024:0.16. After the reaction was complete, 20 phr of polybutylene terephthalate (PBST) was added and the mixture was stirred at a constant temperature for 1 min. The product of Comparative Example 1 was obtained.

[0072] Comparative Example 2

[0073] The product in Comparative Example 1 was purified using the same purification method as in Example 6 to obtain the purified blend in Comparative Example 2.

[0074] Comparative Example 3

[0075] Polyglycolic acid (PGA) (weight-average molecular weight 160,000 g / mol) was purchased from KEBIN-PRAK AB in the Netherlands.

[0076] Comparative Example 4

[0077] Polyglycolic acid and polybutylene terephthalate (PBAT) (weight average molecular weight 40000 g / mol) from Comparative Example 3 were thoroughly premixed at a mass ratio of 80:20, and then mixed with PolyLabHAAKE from Thermo Fisher Scientific, Inc. TM The PGA / PBST blend was melt-mixed using a Rheomex OS 567-1000 internal mixer (rotor diameter: 35 mm, rotor length: 50 mm). The mixing speed was 50 rpm, the temperature was 230 °C, and the mixing time was 5 min. After the reaction was completed, the mixture was directly cooled in air to obtain the PGA / PBST blend.

[0078] The experimental parameters for some of the embodiments and comparative examples are shown in Table 1. In Table 1, PBXT refers to PBST or PBAT.

[0079] Table 1

[0080]

[0081] Detection Example 1

[0082] The pure PGA in Example 6 and Comparative Example 3 were characterized by 1H NMR spectroscopy using deuterated DMSO as the solvent. The comparison results are shown in the figure below. Figure 1 As shown.

[0083] Detection Example 2

[0084] Infrared characterization was performed on the pure PBST and pure PGA from Example 6 and Comparative Example 3, using attenuated total reflectance (ATR) sampling. The resulting images were taken at 1900-1600 cm⁻¹. -1 magnified comparison images within the range are as follows Figure 2 As shown.

[0085] Detection Example 3

[0086] The molecular weights of Examples 1, 2, 6, Comparative Example 1 and Comparative Example 2 were characterized by GPC, and the results are shown in Table 2.

[0087] As shown in Table 2, the molecular weights and their distributions of the examples and the comparative examples are not significantly different, with weight-average molecular weights ranging from 70,000 to 100,000 g / mol.

[0088] Table 2

[0089]

[0090] Detection Example 4

[0091] Example 6 and Comparative Example 2 were characterized by DSC, and the results are shown in Table 3 and... Figure 3 As shown.

[0092] Compared to the distance between the glass transition temperatures of two simple copolymer raw materials (PGA and PBXT in the examples of this invention), block copolymers exhibit a smaller distance between their glass transition temperatures. The smaller the distance between the glass transition temperatures, the better the compatibility between the two components in the block copolymer. However, since the glass transition temperature of a polymer may also be related to its molecular weight and purity, this test example uses Example 6 and Comparative Example 2, which have similar molecular weights and have undergone the same purification process, for comparison.

[0093] By comparing Example 6 with Comparative Example 2, it can be seen that ( Figure 3 ),Depend on Figure 3 It can be seen that the melting point and crystallization temperature of Example 6 are slightly lower than those of Comparative Example 2, and the distance between the two glass transition temperatures of Example 6 is smaller than that of Comparative Example 2.

[0094] Table 3

[0095]

[0096] T g: Glass transition temperature; T mMelting point; ΔH m Enthalpy of fusion; T c Crystallization temperature

[0097] Case 5

[0098] After injection molding tensile test specimens into Example 5 and Comparative Example 1, they underwent cryogenic brittle fracture in liquid nitrogen. Scanning electron microscope (SEM) images of the fracture surfaces were then taken after gold sputtering, specifically the cross-sectional images of the PGA / PBST block copolymer and the PGA / PBST blend. The results are shown in the figures below. Figure 4 and Figure 5 .

[0099] Application examples

[0100] The PGA / PBAT block copolymer obtained in Example 5 was added as a compatibilizer to the PGA / PBST blend obtained in Comparative Example 4, and PolyLab HAAKE from Thermo Fisher Scientific was used. TM The mixture was melt-mixed using a Rheomex OS 567-1000 internal mixer (rotor diameter 35 mm, rotor length 50 mm). The ratio of Example 5 to Comparative Example 4 was 5:100, the rotation speed was 50 rpm, the temperature was 230°C, and the mixing time was 5 min. A product containing the copolymer of the present invention was obtained.

[0101] Mechanical properties were tested on the products in the corresponding use cases and Comparative Example 4. The samples were injection molded into 5A type tensile specimens (thickness: 2 mm) using a HAAKE MiniJet micro-injection molding machine according to GB / T1040.2-2006. The barrel temperature and mold temperature were 230℃ and 50℃, respectively; the injection pressure and time were 300 bar and 5 s, respectively; and the holding pressure and time were 100 bar and 30 s, respectively. Tensile tests were then conducted on an Instron 3344 material testing machine (USA) at a tensile rate of 20 mm / min and a fixture spacing of 50 mm. The results are shown in Table 4.

[0102] Table 4

[0103]

[0104] As shown in Table 4, compared with the product containing the block copolymer of the present invention obtained in Application Example 7, the mechanical properties of the product of simple physical blending without compatibilizer in Comparative Example 4 are significantly improved. The tensile strength and elongation at break are both higher than those of the product without compatibilizer. This indicates that the compatibilizer of the present invention (block copolymer of PGA and PBAT) significantly improves the compatibility of the physically blended PGA / PBAT. Simultaneously, the increase in elongation at break indicates that the toughness of the PGA / PBAT blend is enhanced after adding the compatibilizer of the present invention.

[0105] It was verified that when the products of Examples 1-2 were added as compatibilizers to physically blended PGA / PBST, and when the products of Examples 3-4 were added as compatibilizers to physically blended PGA / PBAT, the mechanical properties of the resulting products were similar to those of the product in Application Example 7. The mechanical properties of the PGA / PBST blend or the PGA / PBAT blend were improved, the compatibility between PGA and PBST or between PGA and PBAT was significantly enhanced, and the toughness was increased.

[0106] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A block copolymer used as a compatibilizer for a blend of aliphatic-aromatic copolyesters and polyglycolic acid, the block copolymer is an A-B diblock copolymer or an A-B-A triblock copolymer, wherein block A is polyglycolic acid and block B is an aliphatic-aromatic copolyester; the weight average molecular weight of the block B is 20000-100000 g / mol; the block copolymer is obtained by one-step melt ring-opening polymerization of glycolide initiated by the aliphatic-aromatic copolyester; the catalyst used for the melt ring-opening polymerization is a salt compound corresponding to one of Sn, Bi, Mg, Al, Ca, Fe, Mn, Ti and Zn; the temperature for the melt ring-opening polymerization is 180-250 ℃; and the reaction time is 3-20 min. 2.The block copolymer of claim 1, wherein: the content of block A is 1 mass%-99 mass%, and the content of block B is 1 mass%-99 mass%, with respect to the total mass of block A and block B. 3.The block copolymer of claim 1, wherein: the content of block A is 65 mass%-95 mass%, and the content of block B is 5 mass%-40 mass%, with respect to the total mass of block A and block B. 4.The block copolymer of claim 1, wherein: the block B is a copolyester formed by condensation polymerization of aliphatic diacid and / or aromatic diacid, and aliphatic diol. 5.The block copolymer of claim 4, wherein: the block B is a copolyester formed by condensation of at least one of α, ω-aliphatic diacid and aromatic diacid containing 2-18 main chain carbon atoms, and at least one aliphatic diol. 6.The block copolymer of claim 5, wherein: the block B is at least one of polybutylene adipate-co-terephthalate, polyethylene adipate-co-terephthalate, polyethylene pimelate-co-terephthalate, and polybutylene pimelate-co-terephthalate. 7.The block copolymer of claim 1, wherein: the block B is polybutylene adipate terephthalate and / or polybutylene pimelate terephthalate. 8.The block copolymer of claim 7, wherein: the block copolymer contains a copolymer with a structural formula as shown in formula (I) and / or formula (II): 9.The block copolymer of claim 8, wherein: x, y, z are the degree of polymerization, each independently an integer of 1000-2000, and m, n are each independently an integer of 300-600. 10.The block copolymer of any one of claims 1-9, wherein: the weight average molecular weight of the block copolymer is 20000-200000 g / mol; and / or, the polydispersity index of the block copolymer is 1-3. 11.The block copolymer of any one of claims 1-9, wherein: the weight average molecular weight of the block copolymer is 80000-160000 g / mol; and / or, ​ ​ ​ ​ wherein R1in formula (I) and formula (II) is each independently or wherein x, y, z are the degree of polymerization, each independently 50-5000, and m, n are each independently 1-1000. ​ ​ ​ ​ ​ ​ ​ The polydispersity coefficient of the block copolymer is 1-2.

12. A method for preparing the block copolymer according to any one of claims 1-11, comprising melt blending reaction of components including glycolide, aliphatic-aromatic copolyester and catalyst in a required amount, and then cooling to obtain the block copolymer.

13. The method according to claim 12, wherein: the mass ratio of glycolide to aliphatic-aromatic copolyester is 100:1-99; and / or, the mass ratio of glycolide to catalyst is 100:(0.005-1).

14. The method according to claim 12, wherein: the mass ratio of glycolide to aliphatic-aromatic copolyester is 100:5-40; and / or, the mass ratio of glycolide to catalyst is 100:(0.01-0.5).

15. The method according to claim 12, wherein: the weight average molecular weight of the aliphatic-aromatic copolyester is 20000-100000 g / mol; and / or, the aliphatic-aromatic copolyester is selected from at least one of the following polymers: polybutylene succinate terephthalate and / or low molecular weight polymers obtained by alcoholysis of polybutylene succinate terephthalate; at least one of low molecular weight polymers obtained by alcoholysis of chain-extended modified polybutylene succinate terephthalate, end-group modified polybutylene succinate terephthalate and polybutylene succinate terephthalate; chain-extended modified polybutylene succinate terephthalate and end-group modified polybutylene succinate terephthalate.

16. The method according to claim 12, wherein: the weight average molecular weight of the aliphatic-aromatic copolyester is 40000-90000 g / mol.

17. The method according to claim 12, wherein: the catalyst is a Sn salt.

18. The method according to any one of claims 12-17, wherein: the preparation process is carried out in a melt mixing device.

19. The method according to any one of claims 12-17, wherein: the temperature of melt blending reaction is 210-230℃; the reaction time is 3-20 min; and / or, the preparation process is carried out in a melt mixing device; the melt mixing device is one or more of a series combination of a tank reactor, a pipe reactor, an internal mixer, a Farrel continuous mixer, a Banbury mixer, a single-screw extruder, a multi-screw extruder and a reciprocating single-screw extruder.

20. The method according to any one of claims 12-17, wherein: the preparation process is carried out in an internal mixer.

21. The method according to claim 20, wherein: the internal mixing temperature is 180-250℃, the rotation speed is 5-150 rpm, and the reaction time is 3-15 min.

22. The method according to claim 20, wherein: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The mixing temperature is 210-230℃, the rotating speed is 20-80rpm, and the reaction time is 5-10min.

23. The preparation method according to any one of claims 12-17, wherein: The preparation process is carried out in a twin-screw extruder.

24. The preparation method according to claim 23, wherein: The processing temperature is 180-250℃, the screw rotating speed is 5-300rpm, and the length-diameter ratio is 30-80.

25. The preparation method according to claim 23, wherein: The processing temperature is 210-230℃, the screw rotating speed is 30-100rpm, and the length-diameter ratio is 40-70.

26. A block copolymer prepared by the preparation method according to any one of claims 12-25.

27. Use of the block copolymer according to any one of claims 1-11, 26 as a compatibilizer in injection molding of aliphatic-aromatic copolyester and polyglycolic acid blends.

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