PBAT with light stability and preparation method thereof

Abstract

The invention provides PBAT (poly (butyleneadipate-co-terephthalate)) with light stability and a preparation method thereof. The preparation method comprises the following steps: carrying out esterification reaction on terephthalic acid, butanediol, adipic acid and a light stabilizer serving as raw materials to obtain an esterification product system; and carrying out condensation polymerization on the esterification product system to obtain PBAT with light stability. The light stabilizer is connected to a main chain of PBAT molecules in a chemical bond combination mode through chemical reaction, molecular chain functionalization is conducted on PBAT, good light stability is given to PBAT, the problems that an additive light stabilizer is poor in compatibility, prone to volatilization, prone to surface migration and the like are effectively solved, then the light stability of PBAT is effectively improved, and the service life of PBAT is prolonged. And the device can be stably used outdoors for a long time.

Description

Technical Field

[0001] This invention relates to a photostable PBAT and its preparation method, belonging to the field of new polymer materials technology. Background Technology

[0002] Polybutylene terephthalate (PBAT) is a fully biodegradable aliphatic-aromatic copolyester with excellent mechanical properties. As a fully biodegradable material, it is currently the preferred material for solving the "white pollution" caused by non-degradable plastics such as polyethylene. However, conventional PBAT polyester lacks light stability, which severely limits its durability in outdoor applications such as agricultural mulch films and packaging bags.

[0003] To improve the photostability of polymers, dispersing small-molecule light stabilizers (such as UV absorbers, free radical scavengers, and quenchers) or UV shielding agents into the polymer during melt processing is the most widely used method. Examples of UV absorbers include salicylate esters and UV-O; examples of UV shielding agents include ZnO, TiO2, and carbon black. However, adding these small-molecule light stabilizers or UV shielding agents faces three main problems: First, the compatibility between the light stabilizers or UV shielding agents and the polymer matrix is ​​limited, and they are almost impossible to distribute uniformly, often resulting in agglomeration within the polymer. Second, due to the high temperatures during processing, highly volatile small-molecule light stabilizers easily evaporate. Third, during application, light stabilizers may migrate from the polymer matrix under the influence of water, oil, and other solvents. These problems weaken the effectiveness of the light stabilizers, thus failing to effectively improve the photostability of the polymer. Therefore, it is necessary to provide a new photostability-based PBAT to address these issues. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a photostable PBAT and its preparation method, wherein the PBAT obtained by the preparation method exhibits good photostable stability.

[0005] To achieve the above objectives, the present invention provides a method for preparing photostable PBAT, comprising: performing an esterification reaction using terephthalic acid, butanediol, adipic acid, and a light stabilizer as raw materials to obtain an esterified product system; and subjecting the esterified product system to a polycondensation reaction to obtain photostable PBAT. The light stabilizer is selected from one or a combination of two or more of epoxide benzophenone, hydroxyethylpiperidine, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 4-(4,6-bishydroxyethoxy-1,3,5-triazine-2-aminobenzenesulfonamide, and 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine.

[0006] In the chemical preparation process of PBAT, rather than the processing process, the PBAT molecular chain is reconstructed and modified using the aforementioned special structure of light stabilizer. Through a chemical reaction, the light stabilizer is chemically bonded to the main chain of the PBAT molecule, thereby functionalizing the PBAT molecular chain. This endows it with better photostability and effectively improves the poor compatibility, volatility, and surface migration problems of additive light stabilizers. In this way, the long-term photostability of PBAT is effectively improved, enabling it to be used stably outdoors for a long time.

[0007] Furthermore, the light stabilizer accounts for 0.05% to 1.5% of the total weight of terephthalic acid, butanediol, and adipic acid, for example, 0.05%, 0.1%, 0.5%, 1%, or 1.5%. Different amounts of light stabilizer have varying effects on improving PBAT performance. The molecular structure of PBAT can be designed according to different improvement effects and product applications. At low light stabilizer contents, the melt viscoelasticity and melt strength of PBAT with side-linked light stabilizer are enhanced, which is beneficial for improving blown film processing stability; however, at higher contents, these properties decrease. At relatively high light stabilizer contents, the mechanical properties of PBAT are improved; at low contents, the improvement is not significant.

[0008] Preferably, the esterification reaction includes: first, mixing terephthalic acid, butanediol, and a light stabilizer to carry out a first esterification reaction until the theoretical water yield reaches more than 85% (the theoretical water yield is the amount of water produced when the terephthalic acid and butanediol react completely), then adding adipic acid to the reaction system to carry out a second esterification reaction, obtaining an esterified product system; or, the esterification reaction includes: mixing terephthalic acid, a first portion of butanediol, and a light stabilizer to carry out a third esterification reaction, mixing adipic acid with a second portion of butanediol to carry out a fourth esterification reaction, and mixing the product systems of the third and fourth esterification reactions to obtain an esterified product system. Prioritizing the esterification reaction between terephthalic acid and butanediol can effectively increase the degree of reaction of terephthalic acid. Different feeding sequences and methods affect the molecular chain structure sequence. Both esterification and polycondensation are thermodynamically reversible reactions. In the first step, terephthalic acid is added. Because of the high content of butanediol that can react with it, the forward migration rate of the reaction is accelerated, resulting in a longer terephthalic acid-containing molecular chain sequence. The growth of this sequence can improve the crystallinity of the product, thereby enhancing its mechanical strength.

[0009] In a preferred embodiment, the esterification reaction includes: mixing terephthalic acid, butanediol, a light stabilizer, and a first catalyst, and carrying out a first esterification reaction at a temperature of 200–240°C to form a first product system; adding adipic acid and a second catalyst to the first product system and carrying out a second esterification reaction at a temperature of 160–190°C to obtain an esterified product system.

[0010] Furthermore, the molar ratio of terephthalic acid to butanediol is 30:100 to 55:150; the molar ratio of adipic acid to terephthalic acid is 70:30 to 45:55.

[0011] Furthermore, the first catalyst, calculated as titanium, has a molar ratio of 1:10000 to 3:1000 of the total molars of terephthalic acid and adipic acid, i.e., the molar ratio of the first catalyst to (molars of terephthalic acid + molars of adipic acid) = 1:10000 to 3:1000; the second catalyst, calculated as titanium, has a molar ratio of 1:10000 to 3:1000 of the total molars of terephthalic acid and adipic acid, i.e., the molar ratio of the second catalyst to (molars of terephthalic acid + molars of adipic acid) = 1:10000 to 3:1000.

[0012] Furthermore, the first and second esterification reactions described above are carried out under a protective gas atmosphere. The protective gas is not specifically limited and can be, for example, nitrogen.

[0013] Furthermore, after the first esterification reaction is completed, the first product system is cooled to below 140°C, and then adipic acid and the second catalyst are added to the first product system and mixed.

[0014] In another preferred embodiment, the esterification reaction includes: mixing terephthalic acid, butanediol (partially), a light stabilizer, and a third catalyst, and carrying out a third esterification reaction at a temperature of 200–240°C to obtain a second product system; mixing adipic acid, butanediol (partially), and a fourth catalyst, and carrying out a fourth esterification reaction at a temperature of 160–190°C to obtain a third product system; and mixing the second product system and the third product system to obtain an esterified product system.

[0015] Furthermore, the molar ratio of terephthalic acid to butanediol in the first part is 100:100 to 100:130; the molar ratio of adipic acid to butanediol in the second part is 100:100 to 100:130; and the molar ratio of adipic acid to terephthalic acid is 70:30 to 45:55.

[0016] Furthermore, the third catalyst, calculated as titanium, has a molar ratio of 1:10000 to 3:1000 of the total molars of terephthalic acid and adipic acid, i.e., the molar ratio of the third catalyst to (molars of terephthalic acid + molars of adipic acid) = 1:10000 to 3:1000; the fourth catalyst, calculated as titanium, has a molar ratio of 1:10000 to 3:1000 of the total molars of terephthalic acid and adipic acid, i.e., the molar ratio of the fourth catalyst to (molars of terephthalic acid + molars of adipic acid) = 1:10000 to 3:1000.

[0017] Furthermore, the third and fourth esterification reactions described above are carried out under a protective gas atmosphere, and the protective gas is not specifically limited, for example, it can be nitrogen.

[0018] Preferably, the reaction temperature of the polycondensation reaction is 220–260°C, and the reaction pressure is 50–200 Pa.

[0019] Preferably, a fifth catalyst is added during the polycondensation reaction; the fifth catalyst is calculated as titanium, and the ratio of the number of moles of the fifth catalyst to the total number of moles of terephthalic acid and adipic acid is 1:10000 to 6:1000, that is, the number of moles of the fifth catalyst: (number of moles of terephthalic acid + number of moles of adipic acid) = 1:10000 to 6:1000.

[0020] Furthermore, after the esterification reaction is completed, the esterification product system is cooled to below 140°C, and then a fifth catalyst is added to the esterification product system.

[0021] In a preferred embodiment, the first catalyst, the second catalyst, the third catalyst, the fourth catalyst, and the fifth catalyst are each independently a multinuclear catalyst, preferably a multinuclear catalyst including a titanium-silicon-zinc multinuclear catalyst and / or a titanium-silicon-aluminum multinuclear catalyst, more preferably a titanium-silicon composite multinuclear catalyst as described in patent application 202210966547.1.

[0022] The present invention also provides a photostable PBAT, which is prepared by the aforementioned method for preparing photostable PBAT. Attached Figure Description

[0023] Figure 1 The carbon NMR spectrum of epoxide benzophenone prepared in one embodiment of the present invention is shown.

[0024] Figure 2 The image shows a sample of PBAT with photostability obtained by aging in a rapid photoaging chamber for 20 days, as shown in Embodiment 1 of the present invention.

[0025] Figure 3The image shows a sample of PBAT with photostability obtained after 20 days of rapid photoaging in an experimental chamber, as shown in Example 3 of the present invention.

[0026] Figure 4 The image shows a sample of PBAT obtained by aging in a rapid light aging chamber for 20 days in Comparative Example 1 of this invention.

[0027] Figure 5 The image shows a sample of PBAT obtained by aging in a rapid light aging chamber for 20 days in Comparative Example 4 of this invention.

[0028] Figure 6 The UV-Vis absorption spectrum of the leaching solution of PBAT with photostability in the ethanol leaching experiment of Example 3 of the present invention is shown.

[0029] Figure 7 The UV-Vis absorption spectrum of the leaching solution of PBAT with photostability in the ethanol leaching experiment of Comparative Example 3 of the present invention is shown. Detailed Implementation

[0030] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0031] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data used in this way can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] (I) Examples of Preparation of Titanium-Silicon-Zinc Multinuclear Catalysts

[0033] This embodiment provides a method for preparing a titanium-silicon-zinc polynuclear catalyst, which includes the following steps:

[0034] (1) Add 0.05 mol of tetrabutyl titanate, 0.005 mol of zinc acetylacetone and 0.1 mol of L-lactic acid dropwise into 1 mol of 1,4-butanediol and stir thoroughly until homogeneous solution A is formed;

[0035] (2) Mix 0.02 mol of tetraethyl silicate with 0.15 mol of ethanol and 0.08 mol of acidic deionized water with a pH of 2.9 to 3.1 evenly and stir at room temperature for 12 h to form solution B;

[0036] (3) Slowly add solution B to solution A and stir quickly until homogeneous. Then, react the resulting solution at 80°C for 3 hours under a pressure range of 150 Pa to remove low-boiling-point components and obtain solution C.

[0037] (4) Add 0.1 mol of acetylacetone to solution C and stir quickly until homogeneous to obtain liquid titanium-silicon composite multinuclear catalyst with a titanium element mass fraction of 2.12 wt%.

[0038] (II) Examples of Preparation of Titanium-Silicon-Aluminum Multinuclear Catalysts

[0039] This embodiment provides a method for preparing a titanium-silicon-aluminum multinuclear catalyst, which includes the following steps:

[0040] (1) Add 0.05 mol of isopropyl titanate, 0.005 mol of aluminum acetylacetonate and 0.05 mol of D-lactic acid to 1 mol of 1,4-butanediol and stir thoroughly until homogeneous solution A is formed;

[0041] (2) Mix 0.01 mol of tetraethyl silicate, 0.07 mol of ethanol, and 0.04 mol of deionized water evenly and stir at room temperature for 12 h to form solution B;

[0042] (3) Slowly add solution B to solution A and stir quickly until homogeneous. Then, react the resulting solution at 80°C for 3 hours under a pressure range of 120 Pa to remove low-boiling-point components and obtain solution C.

[0043] (4) Add 0.12 mol of acetylacetone and 0.005 mol of tartaric acid to solution C and stir quickly until homogeneous to obtain liquid titanium-silicon composite multinuclear catalyst with a titanium element mass fraction of 2.08 wt%.

[0044] (III) Examples of Preparation of Epoxidized Benzophenone

[0045] This embodiment provides a method for preparing epoxidized benzophenone, which includes the following steps:

[0046] (1) Heat and stir 0.05 mol benzophenone, 0.05 mol sodium hydroxide and 25 mL deionized water until homogeneous to form solution A;

[0047] (2) Weigh 0.15 mol of epichlorohydrin into a flask and heat it to 70°C and keep it at a constant temperature;

[0048] (3) Slowly add solution A to epichlorohydrin at a constant temperature of 70°C. After the addition is complete, continue the reaction for 2 hours. Then separate the liquid and wash the collected viscous liquid repeatedly with deionized water until the pH is neutral.

[0049] (4) The obtained viscous liquid was rotary evaporated, and then anhydrous methanol was added. A pale yellow powder solid was slowly precipitated. After drying, epoxide benzophenone was obtained. Figure 1 The carbon NMR spectrum of epoxide benzophenone is shown. The absorption peaks at positions 1, 2, and 3 are characteristic absorption peaks of the epoxide functional group.

[0050] (IV) PBAT Preparation Examples

[0051] Example 1

[0052] This embodiment provides a method for preparing photostable PBAT, which includes the following steps:

[0053] (1) Weighing and mixing of samples: Weigh 17.93g of terephthalic acid and 27g of 1,4-butanediol and add them to a three-necked flask. Add 0.15g of hydroxyethylpiperidine alcohol light stabilizer and 200mg of titanium silicon zinc polynuclear catalyst. Then place the three-necked flask in an oil bath preheated to 50°C.

[0054] (2) First esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the first esterification reaction is completed.

[0055] (3) Second esterification reaction: After the first esterification is completed, the temperature of the oil bath is lowered to below 140℃, 150mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the second time, and 19.27g of adipic acid is added. The temperature of the bath is then raised to 185℃ and esterified for 120min. After the water output reaches 3mL, the second esterification reaction is completed.

[0056] (4) Polycondensation reaction: After the second esterification reaction is completed, the temperature is lowered to below 140℃ again, and 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the third time. The pressure inside the three-necked flask is pumped to 50-200Pa, and the oil bath temperature is raised to 230℃ to carry out the polycondensation reaction for 3h to obtain chemically bonded PBAT with photostability.

[0057] (5) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0058] Example 2

[0059] This embodiment provides a method for preparing photostable PBAT, which includes the following steps:

[0060] (1) Sample weighing and mixing: Weigh 17.93g of terephthalic acid and 27g of 1,4-butanediol and add them to a three-necked flask. Add 0.2g of 2,2'-dihydroxy-4,4'-dimethoxybenzophenone light stabilizer and 200mg of titanium-silicon-zinc polynuclear catalyst. Then place the three-necked flask in an oil bath preheated to 50°C.

[0061] (2) First esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the first esterification reaction is completed.

[0062] (3) Second esterification reaction: After the first esterification is completed, the temperature of the oil bath is lowered to below 140℃, 150mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the second time, and 19.27g of adipic acid is added. The temperature of the bath is then raised to 185℃ and esterified for 120min. After the water output reaches 3mL, the second esterification reaction is completed.

[0063] (4) Polycondensation reaction: After the second esterification reaction is completed, the temperature is lowered to below 140℃ again, and 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the third time. The pressure inside the three-necked flask is pumped to 50-200Pa, and the oil bath temperature is raised to 230℃ to carry out the polycondensation reaction for 3h to obtain chemically bonded PBAT with photostability.

[0064] (5) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0065] Example 3

[0066] This embodiment provides a method for preparing photostable PBAT, which includes the following steps:

[0067] (1) Weighing and mixing of samples: Weigh 17.93g of terephthalic acid and 27g of 1,4-butanediol and add them to a three-necked flask. Add 0.34g of benzophenone epoxide light stabilizer and 200mg of titanium silicon zinc polynuclear catalyst. Then place the three-necked flask in an oil bath preheated to 50°C.

[0068] (2) First esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 15℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the first esterification reaction is completed.

[0069] (3) Second esterification reaction: After the first esterification is completed, the temperature of the oil bath is lowered to below 140℃. 150mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the second time. After adding 19.27g of adipic acid, the temperature of the bath is raised to 185℃ and esterification is carried out for 120min. After the water output reaches 3mL, the second esterification reaction is completed.

[0070] (4) Polycondensation reaction: After the second esterification reaction is completed, the temperature is lowered to below 140℃ again, and 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the third time. The pressure inside the three-necked flask is pumped to 50-200Pa, and the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h to obtain chemically bonded PBAT with photostability.

[0071] (5) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded, photostable PBAT.

[0072] Example 4

[0073] This embodiment provides a method for preparing photostable PBAT, which includes the following steps:

[0074] (1) Sample weighing and mixing: Weigh 17.93g of terephthalic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask A. Add 0.15g of hydroxyethylpiperidinol light stabilizer and 200mg of titanium-silicon-zinc polynuclear catalyst. Place the three-necked flask A in an oil bath preheated to 50°C. Weigh 19.27g of adipic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask B. Add 150mg of titanium-silicon-zinc polynuclear catalyst. Place the three-necked flask B in an oil bath preheated to 50°C.

[0075] (2) Esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask A in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at that temperature for 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the esterification reaction is completed. At the same time, nitrogen gas is continuously introduced into the three-necked flask B in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 180℃ and esterified for 90 min. After the water output reaches 3 mL, the esterification reaction is completed.

[0076] (3) Polycondensation reaction: After the esterification reaction is completed, the temperature is lowered to 140℃, the melts in bottles A and B are mixed together, 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask, the pressure inside the three-necked flask is pumped to 50-200Pa, the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h, and chemically bonded PBAT with photostability is obtained.

[0077] (4) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0078] Example 5

[0079] This embodiment provides a method for preparing photostable PBAT, which includes the following steps:

[0080] (1) Sample weighing and mixing: Weigh 17.93g of terephthalic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask A. Add 0.2g of 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and 200mg of titanium-silicon-zinc polynuclear catalyst. Then place the three-necked flask A in an oil bath preheated to 50°C. Weigh 19.27g of adipic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask B. Add 150mg of titanium-silicon-zinc polynuclear catalyst. Then place the three-necked flask B in an oil bath preheated to 50°C.

[0081] (2) Esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask A in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at that temperature for 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the esterification reaction is completed. At the same time, nitrogen gas is continuously introduced into the three-necked flask B in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 180℃ and esterified for 90 min. After the water output reaches 3 mL, the esterification reaction is completed.

[0082] (3) Polycondensation reaction: After the esterification reaction is completed, the temperature is lowered to 140℃, the melts in bottles A and B are mixed together, 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask, the pressure inside the three-necked flask is pumped to 50-200Pa, the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h, and chemically bonded PBAT with photostability is obtained.

[0083] (4) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0084] Example 6

[0085] This embodiment provides a method for preparing photostable PBAT, which includes the following steps:

[0086] (1) Sample weighing and mixing: Weigh 17.93g of terephthalic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask A. Add 0.34g of benzophenone epoxide light stabilizer and 200mg of titanium silicon zinc polynuclear catalyst. Place the three-necked flask A in an oil bath preheated to 50°C. Weigh 19.27g of adipic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask B. Add 150mg of titanium silicon zinc polynuclear catalyst. Place the three-necked flask B in an oil bath preheated to 50°C.

[0087] (2) Esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask A in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at that temperature for 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the esterification reaction is completed. At the same time, nitrogen gas is continuously introduced into the three-necked flask B in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 180℃ and esterified for 90 min. After the water output reaches 3 mL, the esterification reaction is completed.

[0088] (3) Polycondensation reaction: After the esterification reaction is completed, the temperature is lowered to 140℃, the melts in bottles A and B are mixed together, 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask, the pressure inside the three-necked flask is pumped to 50-200Pa, the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h, and chemically bonded PBAT with photostability is obtained.

[0089] (4) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0090] Example 7

[0091] This embodiment provides a method for preparing photostable PBAT, which includes the following steps:

[0092] (1) Sample weighing and mixing: Weigh 17.93g of terephthalic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask A. Add 0.34g of 4-(4,6-bis(hydroxyethoxy-1,3,5-triazine-2-aminobenzenesulfonamide) and 200mg of titanium-silicon-zinc polynuclear catalyst. Place the three-necked flask A in an oil bath preheated to 50°C. Weigh 19.27g of adipic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask B. Add 150mg of titanium-silicon-zinc polynuclear catalyst. Place the three-necked flask B in an oil bath preheated to 50°C.

[0093] (2) Esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask A in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at that temperature for 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the esterification reaction is completed. At the same time, nitrogen gas is continuously introduced into the three-necked flask B in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 180℃ and esterified for 90 min. After the water output reaches 3 mL, the esterification reaction is completed.

[0094] (3) Polycondensation reaction: After the esterification reaction is completed, the temperature is lowered to 140℃, the melts in bottles A and B are mixed together, 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask, the pressure inside the three-necked flask is pumped to 50-200Pa, the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h, and chemically bonded PBAT with photostability is obtained.

[0095] (4) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0096] Example 8

[0097] This embodiment provides a method for preparing photostable PBAT, which includes the following steps:

[0098] (1) Sample weighing and mixing: Weigh 17.93g of terephthalic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask A. Add 0.2g of 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine and 200mg of titanium-silicon-zinc polynuclear catalyst. Place the three-necked flask A in an oil bath preheated to 50°C. Weigh 19.27g of adipic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask B. Add 150mg of titanium-silicon-zinc polynuclear catalyst. Place the three-necked flask B in an oil bath preheated to 50°C.

[0099] (2) Esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask A in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at that temperature for 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the esterification reaction is completed. At the same time, nitrogen gas is continuously introduced into the three-necked flask B in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 180℃ and esterified for 90 min. After the water output reaches 3 mL, the esterification reaction is completed.

[0100] (3) Polycondensation reaction: After the esterification reaction is completed, the temperature is lowered to 140℃, the melts in bottles A and B are mixed together, 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask, the pressure inside the three-necked flask is pumped to 50-200Pa, the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h, and chemically bonded PBAT with photostability is obtained.

[0101] (4) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0102] Comparative Example 1

[0103] This comparative example provides a method for preparing PBAT, which includes the following steps:

[0104] (1) Weighing and mixing of samples: Weigh 17.93g of terephthalic acid and 27g of 1,4-butanediol and add them to a three-necked flask. Add 200mg of titanium silicon zinc polynuclear catalyst and place the three-necked flask in an oil bath preheated to 50°C.

[0105] (2) First esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask in step (1), the stirring device is turned on, the stirring speed is set to 250 r / min, the oil bath is heated to 190℃ and kept at 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 20℃ every 30 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the first esterification reaction is completed.

[0106] (3) Second esterification reaction: After the first esterification is completed, the temperature of the oil bath is lowered to below 140℃. 150mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the second time. 19.27g of adipic acid is added and the temperature of the bath is raised to 185℃ for esterification for 120min. After the water output reaches 3mL, the second esterification reaction is completed.

[0107] (4) Polycondensation reaction: After the second esterification reaction is completed, the temperature is lowered to below 140℃ again, and 2500mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the third time. The pressure inside the three-necked flask is pumped to 50-200Pa, and the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h to obtain linear PBAT.

[0108] (5) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain linear PBAT.

[0109] Comparative Example 2

[0110] This comparative example provides a method for preparing PBAT, which includes the following steps:

[0111] (1) Sample weighing and mixing: Weigh 17.93g of terephthalic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask A. Add 150mg of titanium-silicon-zinc polynuclear catalyst and place the three-necked flask A in an oil bath preheated to 50°C. Weigh 19.27g of adipic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask B. Add 200mg of titanium-silicon-zinc polynuclear catalyst and place the three-necked flask B in an oil bath preheated to 50°C.

[0112] (2) Esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask A in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at that temperature for 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 90 min. After the water output reaches 3 mL, the esterification reaction is completed. At the same time, nitrogen gas is continuously introduced into the three-necked flask B in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 180℃ and esterified for 90 min. After the water output reaches 3 mL, the esterification reaction is completed.

[0113] (3) Polycondensation reaction: After the esterification reaction is completed, the temperature is lowered to 140℃, the melts in bottles A and B are mixed together, 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask, and the pressure inside the three-necked flask is pumped to 50-200Pa. The oil bath temperature is raised to 230℃ for polycondensation reaction for 3h to obtain linear PBAT.

[0114] (4) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain linear PBAT.

[0115] Comparative Example 3

[0116] This comparative example is a blend of 0.3% by mass of the small molecule UV absorber 2,4-dihydroxybenzophenone and PBAT prepared by melt blending.

[0117] First, PBAT (provided by Xinjiang Lanshan Tunhe Chemical Group) was stored in a vacuum oven at 80℃ for 24 hours to remove moisture. Then, 50 grams of PBAT and 0.15 grams of 2,4-dihydroxybenzophenone were weighed and placed in a Hacker internal mixer for blending. The mixer temperature was set to 160℃ and the rotor speed to 90 rpm. After mixing for 10 minutes, the product was obtained.

[0118] Comparative Example 4

[0119] This comparative example provides a method for preparing PBAT, which includes the following steps:

[0120] (1) Weighing and mixing of samples: Weigh 17.93g of terephthalic acid and 27g of 1,4-butanediol and add them to a three-necked flask. Add 0.43g of triazine-5 light stabilizer and 200mg of titanium silicon zinc polynuclear catalyst. Then place the three-necked flask in an oil bath preheated to 50°C.

[0121] (2) First esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 15℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the first esterification reaction is completed.

[0122] (3) Second esterification reaction: After the first esterification is completed, the temperature of the oil bath is lowered to below 140℃. 150mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the second time. After adding 19.27g of adipic acid, the temperature of the bath is raised to 185℃ and esterification is carried out for 120min. After the water output reaches 3mL, the second esterification reaction is completed.

[0123] (4) Polycondensation reaction: After the second esterification reaction is completed, the temperature is lowered to below 140℃ again, and 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask for the third time. The pressure inside the three-necked flask is pumped to 50-200Pa, and the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h to obtain chemically bonded PBAT with photostability.

[0124] (5) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0125] Comparative Example 5

[0126] This comparative example provides a method for preparing PBAT, which includes the following steps:

[0127] (1) Sample weighing and mixing: Weigh 17.93g of terephthalic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask A. Add 0.43g of triazine-5 light stabilizer and 200mg of titanium-silicon-zinc polynuclear catalyst. Place the three-necked flask A in an oil bath preheated to 50°C. Weigh 19.27g of adipic acid and 12.15g of 1,4-butanediol and add them to a three-necked flask B. Add 200mg of titanium-silicon-zinc polynuclear catalyst. Place the three-necked flask B in an oil bath preheated to 50°C.

[0128] (2) Esterification reaction: Nitrogen gas is continuously introduced into the three-necked flask A in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 190℃ and kept at that temperature for 20 min, and then the oil bath temperature is gradually increased to 215℃ at a rate of 10℃ every 20 min. Esterification is carried out at 215℃ for 60 min. After the water output reaches 3 mL, the esterification reaction is completed. At the same time, nitrogen gas is continuously introduced into the three-necked flask B in step (1), the stirring device is turned on, the stirring speed is set to 260 r / min, the oil bath is heated to 180℃ and esterified for 90 min. After the water output reaches 3 mL, the esterification reaction is completed.

[0129] (3) Vacuum polycondensation reaction: After the esterification reaction is completed, the temperature is lowered to 140℃, the melts in bottles A and B are mixed together, 250mg of titanium silicon zinc polynuclear catalyst is added to the three-necked flask, and the pressure inside the three-necked flask is pumped to 50-200Pa. Then, the oil bath temperature is raised to 230℃ for polycondensation reaction for 3h to obtain chemically bonded PBAT with photostability.

[0130] (4) Finally, the obtained PBAT is removed from the three-necked flask and dried to obtain chemically bonded PBAT with photostability.

[0131] Performance characterization:

[0132] (1) The PBAT obtained in the examples and comparative examples were respectively subjected to rapid photoaging chamber (65℃, light intensity 0.70w / m²). 2 The product was irradiated with light at a wavelength of 340 nm for 20 days, and its mechanical properties before and after aging were tested. The test results are shown in Table 1.

[0133] Table 1

[0134]

[0135]

[0136] Figure 2 The image shows a sample of PBAT with photostability obtained by aging in a rapid photoaging chamber for 20 days in Embodiment 1 of the present invention. No obvious cracks appeared on the surface, and it still retained good mechanical strength.

[0137] Figure 3 The image shows a sample of PBAT with photostability obtained by aging in a rapid photoaging chamber for 20 days in Embodiment 3 of the present invention. No obvious cracks appeared on the surface, and it still retained good mechanical strength.

[0138] Figure 4 The photographs of the PBAT samples obtained by aging in a rapid light aging chamber for 20 days in Comparative Example 1 of this invention are shown. They show obvious cracking and even break into two pieces with a light touch, almost losing all mechanical properties.

[0139] Figure 5 The image shows a sample of PBAT obtained by rapid photoaging in a light aging chamber for 20 days in Comparative Example 4 of this invention. Although there is no obvious cracking on the surface, it has almost lost all mechanical strength.

[0140] Through Table 1 and Figures 2-4 To further illustrate, compared to not adding light stabilizers (e.g., Comparative Examples 1 and 2) or adding light stabilizers during processing (e.g., Comparative Example 3), the present invention (e.g., Examples 1-8) uses a chemical reaction to link the light stabilizer to the main chain of the PBAT molecule through chemical bonding, thereby functionalizing the PBAT molecular chain, endowing it with better photostability, and effectively improving the poor compatibility, volatility, and surface migration problems of additive light stabilizers. This effectively enhances the long-term photostability of PBAT, enabling it to be used stably outdoors for a long time.

[0141] Through Table 1 and Figure 2 , Figure 3 and Figure 5It can be further explained that, compared to other light stabilizers (e.g., Comparative Examples 4 and 5), the present invention (e.g., Examples 1-8) uses the aforementioned special structure of light stabilizer to reconstruct and modify the PBAT molecular chain, which can significantly improve the long-term photostability of PBAT. The optical properties of epoxidized benzophenone can be explained by the interconversion of its two tautomers. Under ultraviolet irradiation, o-hydroxybenzophenone undergoes a conversion between the keto and enol forms. The enol form releases heat and then reverts back to the keto form. This rapid conversion dissipates ultraviolet energy, thus achieving a photostability effect. Hydroxyethylpiperidinol can capture the oxidizing substances produced by PBAT during photo-oxidative degradation, thereby being oxidized into nitric oxide radicals, thus achieving a photostability effect. In this experiment, the ultraviolet wavelength parameter used for rapid photoaging was 340 nm, which is the most suitable absorption wavelength range for epoxidized benzophenone, resulting in good protective effect. The photostability of triazine-5 is relatively weak, which is related to the content of the light stabilizer. In triazine-5, the steric hindrance of the molecular substituents is large, which reduces the reactivity. Under the same molar amount of feed as other reactive light stabilizers, its content incorporated into the PBAT molecular backbone is lower, resulting in poorer light stabilization effect.

[0142] (2) The products from Example 3 and Comparative Example 3 were made into mechanical tensile specimens and placed in ethanol for ethanol leaching experiments at room temperature. The leaching solution was measured at regular intervals using a UV-Vis spectrophotometer with a detection wavelength of 250-750 nm. The absorbance of the light stabilizer was measured at a characteristic wavelength of about 323 nm to detect the leaching of the light stabilizer.

[0143] Figure 6 The UV-Vis absorption spectrum of the leaching solution of PBAT with photostability in the ethanol leaching experiment of Example 3 of the present invention is shown. Figure 7 The UV-Vis absorption spectrum of the leaching solution of PBAT with photostability in the ethanol leaching experiment of Comparative Example 3 of this invention is shown. The UV-Vis spectrophotometric spectra of the leaching solutions of PBAT in Examples 3 and 3 after immersion in ethanol solvent at room temperature show that no photostability peak was observed in Example 3, indicating that no photostability peak was detected in the leaching solution. The photostability peak is covalently bonded to the PBAT molecular chain, and PBAT still exhibits very good photostability. In Comparative Example 3, a photostability peak was observed at 323 nm, and the final leaching content was over 90%, indicating that a large amount of photostability was leached out from the blended PBAT under ethanol immersion, thus losing its protective effect on PBAT.

[0144] Furthermore, after the products in Comparative Example 3 and Example 3 were made into mechanical tensile specimens and subjected to ethanol leaching tests, they were then subjected to rapid light aging in a rapid light aging chamber (65°C, light intensity 0.70 W / m²). 2The product was irradiated with light at a wavelength of 340 nm for 20 days, and its mechanical properties before and after aging were tested. The product in Comparative Example 3 showed obvious cracking and could not be tested for tensile properties, while the product in Example 3 had a tensile strength of 9.5 MPa and an elongation at break of 850% after aging, and still retained good mechanical properties.

Claims

1. A process for the preparation of PBAT having light stability, wherein, The method comprises the following steps: an esterification product system is obtained by esterification reaction with terephthalic acid, butanediol, adipic acid and a light stabilizer; polycondensation reaction is performed on the esterification product system to obtain the PBAT with light stability; the light stabilizer is selected from one or more than two combinations of epoxidized benzophenone, hydroxyethyl piperidine alcohol, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 4-(4,6-bishydroxyethoxy-1,3,5-triazine-2-aminobenzenesulfonamide and 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine.

2. The method of preparing PBAT with light stability according to claim 1, wherein, The weight of the light stabilizer accounts for 0.05-1.5% of the total weight of the terephthalic acid, the butanediol and the adipic acid.

3. The method of claim 1, wherein the PBAT having light stability is prepared by adding the antioxidant to the PBAT. The esterification reaction comprises the following steps: first, the terephthalic acid, the butanediol and the light stabilizer are mixed to perform a first esterification reaction until the theoretical water output reaches more than 85%, and then the adipic acid is added to the reaction system to perform a second esterification reaction, thereby obtaining the esterification product system. Alternatively, the esterification reaction comprises the following steps: the terephthalic acid, a first part of the butanediol and the light stabilizer are mixed to perform a third esterification reaction; the adipic acid and a second part of the butanediol are mixed to perform a fourth esterification reaction; and the product system of the third esterification reaction and the product system of the fourth esterification reaction are mixed to obtain the esterification product system.

4. The method of claim 3, wherein the PBAT having light stability is prepared by adding the antioxidant to the PBAT. The esterification reaction comprises the following steps: the terephthalic acid, the butanediol, the light stabilizer and a first catalyst are mixed to perform the first esterification reaction under the temperature condition of 200-240℃ to form a first product system; the adipic acid and a second catalyst are added to the first product system to perform the second esterification reaction under the temperature condition of 160-190℃, thereby obtaining the esterification product system.

5. The method of claim 4, wherein the PBAT having light stability is prepared by adding the antioxidant to the PBAT. The molar ratio of the terephthalic acid to the butanediol is 30:100-55:150; The molar ratio of the adipic acid to the terephthalic acid is 70:30-45:

55.

6. The method of claim 5, wherein the PBAT having light stability is prepared by adding the antioxidant to the PBAT. The first catalyst and the second catalyst are each independently a titanium-silicon composite multi-nuclear catalyst; The first catalyst is calculated by titanium, and the ratio of the number of moles of the first catalyst to the total number of moles of the terephthalic acid and the adipic acid is 1:10000-3:1000; The second catalyst is calculated by titanium, and the ratio of the number of moles of the second catalyst to the total number of moles of the terephthalic acid and the adipic acid is 1:10000-3:1000.

7. The method of preparing PBAT with light stability according to claim 3, wherein, The esterification reaction comprises the following steps: the terephthalic acid, a first part of the butanediol, the light stabilizer and a third catalyst are mixed to perform the third esterification reaction under the temperature condition of 200-240℃ to obtain a second product system; the adipic acid, a second part of the butanediol and a fourth catalyst are mixed to perform the fourth esterification reaction under the temperature condition of 160-190℃ to obtain a third product system; the second product system and the third product system are mixed to obtain the esterification product system.

8. The method of claim 7, wherein the PBAT having light stability is prepared by adding the antioxidant to the PBAT. The molar ratio of the terephthalic acid to the first part of the butanediol is 100:100-100:130; The molar ratio of the adipic acid to the second part of the butanediol is 100:100-100:130; The molar ratio of the adipic acid to the terephthalic acid is 70:30-45:

55.

9. The method of claim 8, wherein the PBAT having light stability is prepared by adding the antioxidant to the PBAT in the form of a masterbatch. The third catalyst and the fourth catalyst are each independently a titanium-silicon composite multi-core catalyst; The molar ratio of the third catalyst to the total moles of the terephthalic acid and the adipic acid is 1:10000-3:1000, calculated based on titanium; the molar ratio of the fourth catalyst to the total moles of the terephthalic acid and the adipic acid is 1:10000-3:1000, calculated based on titanium.

10. The method of preparing PBAT having light stability according to claim 1, wherein, The reaction temperature of the polycondensation reaction is 220-260℃, and the reaction pressure is 50-200Pa.

11. The method of preparing PBAT having light stability according to claim 1, wherein, A fifth catalyst is added during the polycondensation reaction; the fifth catalyst is a titanium-silicon composite multi-core catalyst; the molar ratio of the fifth catalyst to the total moles of the terephthalic acid and the adipic acid is 1:10000-6:1000, calculated based on titanium.

12. A PBAT having light stability, wherein, Prepared by the method of any one of claims 1-11. Prepared by the method of any one of claims 1-11.

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