Biodegradable anti-aging agent as well as preparation method and application thereof

Abstract

The invention discloses a biodegradable anti-aging agent as well as a preparation method and application thereof, and belongs to the field of biodegradable high polymer materials. Dibasic acid, dihydric alcohol and an acid compound containing a hindered phenol structure or an ester derivative of the acid compound are used as raw materials, esterification and condensation polymerization are performed, and then esterification or ester exchange reaction is performed to prepare the macromolecular anti-aging agent, so that high dispersity and migration resistance are realized; the anti-aging agent and the biodegradable resin are mixed and directly subjected to blow molding, film forming, extrusion casting and other melt forming, the hot working process is simplified, and the loss of material mechanics and aging resistance is reduced; the phenolic hydroxyl group can capture free radicals, so that the aging resistance of the biodegradable material is remarkably improved, and the service life of the material is prolonged. The prepared anti-aging biodegradable material can be applied to thin film products, and is particularly suitable for high-performance degradable mulching films and environment-friendly packaging materials.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable materials technology, specifically relating to a biodegradable antioxidant, its preparation method, and its application. Background Technology

[0002] Replacing plastics that are difficult to recycle in single-use scenarios with biodegradable materials is an effective way to reduce environmental leakage and prevent plastic pollution. However, biodegradable materials often have insufficient aging resistance, especially under complex environmental conditions such as continuous sunlight and alternating temperature and humidity, their mechanical strength and structural integrity are prone to rapid decline, affecting the durability and reliability of the material's functions.

[0003] Currently, the main technical method to improve the aging resistance of biodegradable materials is to add antioxidants. For example, Chinese patent CN120082025A discloses a method for preparing aging-resistant biodegradable copolyesters by adding crosslinking agents, catalysts, stabilizers, anti-hydrolysis agents, and antioxidants, which significantly improves the material's resistance to damp heat aging, thereby extending the shelf life of the product. Chinese patent CN117050481A discloses a PBAT composite material for agricultural films that is resistant to light aging and hydrolysis, using powder chain extender 6902 to avoid introducing short polymer groups while extending the chain, and achieving the purpose of absorbing moisture through water molecule-polyglycerol exchange in zeolite powder. However, the technical means to improve the aging resistance of biodegradable copolyesters in the above patents are mostly concentrated in the modification and processing stage. Adding antioxidants to slow down aging often leads to a decrease in the mechanical properties and long-term durability of the material due to compatibility and migration problems, and even poses potential problems in biosafety and environmental safety.

[0004] Therefore, there is an urgent need to develop an anti-aging agent that can significantly improve the aging resistance of biodegradable materials while maintaining their good mechanical properties, so as to promote the large-scale application of these materials. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a biodegradable antioxidant and its preparation method. The method involves preparing a macromolecular antioxidant with a hindered phenolic structure through esterification, polycondensation, and reaction with a modifier (esterification or transesterification), thereby achieving high dispersibility and anti-migration properties of the antioxidant.

[0006] Another objective of this invention is to propose an aging-resistant biodegradable material, which directly molds an antioxidant and a biodegradable resin, simplifying the thermal processing, simplifying the production process, and enabling large-scale industrial production.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A first aspect of the present invention is to provide a biodegradable antioxidant comprising a reaction product of a diacid, a diol, and a modifier, wherein the modifier is selected from at least one of an acid compound having a hindered phenolic structure or an ester derivative thereof.

[0009] According to the present invention, in the biodegradable anti-aging agent: The dicarboxylic acid is selected from at least one of aromatic dicarboxylic acids and aliphatic dicarboxylic acids; preferably, the aromatic dicarboxylic acid is terephthalic acid, and / or, the aliphatic dicarboxylic acid is selected from at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, and sebacic acid; and / or, The diol is selected from at least one aliphatic diol, preferably from at least one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptahydrol, octanediol, nonanediol, and decanediol; and / or, The modifier can be a common acid compound with a hindered phenolic structure or its ester derivative. Preferably, the modifier is selected from at least one of gallic acid, linalic acid, ferulic acid, sinapic acid, p-coumaric acid, bisphenolic acid, p-hydroxyphenylpropionic acid, 3,5-di-tert-butyl-4-hydroxyphenylacetic acid, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, or ester derivatives of the above compounds. The ester derivative is an esterification product of the above-mentioned acid compound with a hindered phenolic structure and an aliphatic alcohol, preferably an esterification product of the above-mentioned acid compound with a hindered phenolic structure and at least one of methanol, ethanol, propanol, and butanol.

[0010] A second aspect of the present invention is to provide a method for preparing the biodegradable antioxidant described in the first aspect of the present invention, comprising the steps of subjecting a component including a diacid and a diol to an esterification reaction and a polycondensation reaction, followed by a reaction with a modifier.

[0011] According to the present invention, the preparation method of the biodegradable antioxidant specifically includes the following steps: (1) The components containing diacids and diols are subjected to esterification reaction under the action of catalyst C1; (2) The product obtained after the esterification reaction in step (1) is subjected to polycondensation reaction to obtain a hydroxyl-terminated copolyester; (3) The hydroxyl-terminated copolyester obtained in step (2) is reacted with the modifier under the action of catalyst C2 (esterification reaction or transesterification reaction) to obtain the biodegradable antioxidant.

[0012] According to the present invention, in the preparation method of the biodegradable anti-aging agent: The dicarboxylic acid is selected from at least one of aromatic dicarboxylic acids and aliphatic dicarboxylic acids; preferably, the aromatic dicarboxylic acid is terephthalic acid, and / or, the aliphatic dicarboxylic acid is selected from at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, and sebacic acid; when the dicarboxylic acid contains both aromatic dicarboxylic acids and aliphatic dicarboxylic acids, the molar ratio of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid can be adjusted within a wide range, for example, the molar ratio of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid is ≤1:1, preferably 1:(1~1.5); and / or, The diol is selected from at least one aliphatic diol, preferably from at least one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptahydrol, octanediol, nonanediol, and decanediol; and / or, The molar ratio of the diol to the diacid is (1~2):1, preferably (1.2~1.6):1; and / or, The modifier can be a common acid compound with a hindered phenolic structure or its ester derivative. Preferably, the modifier is selected from at least one of gallic acid, linalic acid, ferulic acid, sinapic acid, p-coumaric acid, bisphenolic acid, p-hydroxyphenylpropionic acid, 3,5-di-tert-butyl-4-hydroxyphenylacetic acid, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, or ester derivatives of the above compounds. The ester derivative is an esterification product of the above-mentioned acid compound with a hindered phenolic structure and an aliphatic alcohol, preferably an esterification product of the above-mentioned acid compound with a hindered phenolic structure and at least one of methanol, ethanol, propanol, and butanol. The molar amount of the modifier is 0.005~2.0 mol% of the total molar amount of the diacid, preferably 0.015~0.5 mol%; and / or, The catalyst C1 and catalyst C2 may be the same or different, and are independently selected from at least one of titanium-based catalysts, germanium-based catalysts, tin-based catalysts, and guanidine catalysts, preferably from at least one of titanium dioxide, titanate catalysts, antimony trioxide, antimony acetate, antimony glycolate, bicyclic guanidine, guanidine acetate, guanidine glycolate, and bicyclic guanidine; wherein, the titanate catalyst can be a commonly used titanate compound, such as, but not limited to, tetrabutyl titanate and diisopropyl titanate; the antimony-based catalyst includes, but is not limited to, antimony trioxide, antimony acetate, and antimony glycolate; and the organic guanidine catalyst includes, but is not limited to, bicyclic guanidine and guanidine acetate; the amount of the catalyst is not particularly limited and can be added according to common methods; and / or, There is no particular limitation on the amount of catalyst C1 or catalyst C2, and it can be added according to the usual amount. For example, the amount of catalyst C1 or catalyst C2 is 0.5~1.0 mol of the dicarboxylic acid.

[0013] According to the present invention, in the preparation method of the biodegradable anti-aging agent: The esterification reaction is carried out under a protective gas atmosphere at a temperature of 120–220°C for 1–5 hours. The protective gas can be commonly used nitrogen or an inert gas (such as argon); and / or, The conditions for the polycondensation reaction are: 220~260℃, pressure <50 Pa, and time 0.2~6 h; and / or, The reaction conditions in step (3) are: carried out in a protective gas atmosphere, at a temperature of 120~220℃ and for a time of 0.2~1 h. The protective gas can be commonly used nitrogen or an inert gas (such as argon).

[0014] A third aspect of the present invention is to provide an aging-resistant biodegradable material comprising a polymer and an antioxidant, wherein the antioxidant is the biodegradable antioxidant described in the first aspect of the present invention or a biodegradable antioxidant obtained by the preparation method described in the second aspect of the present invention.

[0015] According to the present invention, in the aging-resistant biodegradable material: The polymer can be a commonly used biodegradable polymer in the prior art. For example, the polymer is selected from at least one of biodegradable aromatic-aliphatic copolyesters and biodegradable aliphatic copolyesters, preferably from at least one of polybutylene terephthalate, polybutylene terephthalate, polybutylene succinate, and polybutylene succinate; and / or, Based on a total weight of 100wt% for the aging-resistant biodegradable material, the antioxidant has a mass percentage content of 5-50wt%, preferably 10-30wt%.

[0016] A fourth aspect of the present invention is to provide a method for preparing the aging-resistant biodegradable material described in the third aspect of the present invention, comprising a step of mixing components including a polymer and an antioxidant and then performing melt processing. The melt processing can employ commonly used melt processing equipment and conditions in the art, including but not limited to extrusion molding, injection molding, blow molding, and extrusion casting. Preferably, the melt processing temperature is 120~190°C.

[0017] This invention uses diacids, diols, and acid compounds or their ester derivatives containing hindered phenolic structures as raw materials. Through esterification, polycondensation, and further esterification or transesterification, a macromolecular antioxidant is prepared, achieving high dispersibility and anti-migration properties. The antioxidant is then mixed with biodegradable resin for direct blow molding, extrusion casting, and other melt molding processes, simplifying the thermal processing and reducing the loss of material mechanical and aging resistance properties. The phenolic hydroxyl groups can capture free radicals, significantly improving the aging resistance of biodegradable materials and extending their service life. The aging-resistant biodegradable materials prepared by this invention can be applied to film products, and are particularly suitable for high-performance biodegradable mulch films and environmentally friendly packaging materials. Attached Figure Description

[0018] Figure 1 The longitudinal and transverse tensile strengths of the aging-resistant biodegradable films A1, A2, and A3 prepared in Example 5 and the PBAT film of Comparative Example 1 during the ultraviolet aging process are shown, where MD represents the longitudinal direction and TD represents the transverse direction.

[0019] Figure 2 The longitudinal and transverse elongation at break during the UV aging process of the aging-resistant biodegradable films A1, A2, A3 prepared in Example 5 and the PBAT film of Comparative Example 1 are shown, where MD represents the longitudinal direction and TD represents the transverse direction.

[0020] Figure 3 The longitudinal and transverse tensile strengths of the aging-resistant biodegradable films A4, A5, and A6 prepared in Example 6 and the PBAT film of Comparative Example 1 during the ultraviolet aging process are shown, where MD represents the longitudinal direction and TD represents the transverse direction.

[0021] Figure 4 The longitudinal and transverse elongation at break during the UV aging process of the aging-resistant biodegradable films A4, A5, and A6 prepared in Example 6 and the PBAT film of Comparative Example 1 are shown, where MD represents the longitudinal direction and TD represents the transverse direction.

[0022] Figure 5 The longitudinal and transverse tensile strengths of the aging-resistant biodegradable films B1, B2, and B3 prepared in Example 7 and the PBS film of Comparative Example 2 during the UV aging process are given, where MD represents the longitudinal direction and TD represents the transverse direction.

[0023] Figure 6 The longitudinal and transverse elongation at break during the UV aging process of the aging-resistant biodegradable films B1, B2, and B3 prepared in Example 7 and the PBS film of Comparative Example 2 are shown, where MD represents the longitudinal direction and TD represents the transverse direction.

[0024] Figure 7The transverse tensile strength and elongation at break of the aging-resistant biodegradable film A1 prepared in Example 5, the aging-resistant biodegradable films C1 and C2 prepared in Example 8, and the PBAT film of Comparative Example 1 were measured during the ultraviolet aging process.

[0025] Figure 8 The migration curves of the aging-resistant biodegradable film A6 prepared in Example 6 and the PBAT film prepared in Comparative Example 3 in ethanol are shown. Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific 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.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] The testing instruments and conditions used in this embodiment are as follows: Relative molecular mass determination: Gel permeation chromatography was performed using a Shimadzu GPC-20A column with tetrahydrofuran as the mobile phase, a flow rate of 0.4 mL / min, and a column temperature of 40℃.

[0032] Tensile property test: conducted according to GB / T1040.3-2006 on a SANS CMT6104 instrument, using type 2 specimens, with a tensile speed of 50 mm / min.

[0033] Aging performance testing: Accelerated weathering performance of the film was tested according to GB / T 16422.3-2022 using a Q-PANELLAB test chamber (QUV) equipped with a UVA-340 ultraviolet lamp. The black-bottom temperature (BPT) of the dark chamber was 60℃, and a 12-hour exposure cycle was used, with each cycle consisting of 8 hours of UV radiation and 4 hours of no-irradiation condensation. The incident light intensity was 0.76 W / m². 2 The wavelength is 340 nm.

[0034] Migration resistance test: Ethanol was used as the immersion solvent for the film, and the solvent was changed at certain time intervals. The immersion solution was analyzed by UV-Vis spectroscopy using a Shimadzu UV3600. The GA ethanol standard solution was used at OD... 270 nm A standard curve of absorbance was used to determine the concentration of GA in the migrating solution.

[0035] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0036] Terephthalic acid (TA), adipic acid (AA), succinic acid (SA), and 1,4-butanediol (1,4-BDO) were purchased from Aladdin Biochemical Technology Co., Ltd. Gallic acid (GA), sinapic acid, 3,5-di-tert-butyl-4-hydroxyphenylacetic acid, and bicyclic guanidine (TBD) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd. PBAT resin and PBS resin are graded TH801T and TH803S, respectively, and are manufactured by Xinjiang Lanshan Tunhe Polyester Co., Ltd.

[0037] Example 1: Preparation of Antioxidant (1) Esterification reaction: Adipic acid, terephthalic acid, 1,4-butanediol and bicyclic guanidine are mixed in a molar ratio of 100:100:280:5. The reaction is carried out under a nitrogen atmosphere at 170℃ for 1 h and 210℃ for 3 h until 95% theoretical water is collected.

[0038] (2) Polycondensation reaction: The system pressure is controlled to be <50 Pa, the temperature is slowly raised to 240℃ within 1 h, the polycondensation reaction is carried out for 4 h, N2 is introduced and the temperature is lowered to 220℃, 1 mol‰ of gallic acid (GA) is added, the reaction is carried out for 30 min, the material is discharged and pelletized to obtain the antioxidant.

[0039] Using the preparation process of steps (1) to (2) above, the polycondensation reaction time in step (2) is changed to prepare antioxidants with polycondensation time of 4 h, 4.5 h and 5 h respectively, which are denoted as a1, a2 and a3 respectively.

[0040] Example 2 Preparation of Antioxidant (1) Esterification reaction: Succinic acid, 1,4-butanediol and bicyclic guanidine are mixed in a molar ratio of 100:140:3 and reacted at 170℃ for 1 h under a nitrogen atmosphere until 95% theoretical water is collected.

[0041] (2) Polycondensation reaction: The system pressure is controlled to be <50 Pa, the temperature is slowly raised to 240℃ within 1 h, the reaction is carried out for 4 h, N2 is introduced and the temperature is lowered to 220℃, 1 mol‰ of gallic acid (GA) is added, the reaction is carried out for 30 min, the material is discharged and pelletized to obtain the antioxidant.

[0042] Using the preparation process of steps (1) to (2) above, the polycondensation reaction time in step (2) is changed to prepare antioxidants with polycondensation time of 4 h, 4.5 h and 5 h respectively, which are denoted as b1, b2 and b3 respectively.

[0043] Example 3 Preparation of Antioxidant Same as steps (1) to (2) of Example 1, except that gallic acid in step (2) is replaced with sinapic acid to prepare an antioxidant, denoted as c1.

[0044] Same as steps (1) to (2) of Example 1, except that gallic acid in step (2) is replaced with 3,5-di-tert-butyl-4-hydroxyphenylacetic acid to prepare an antioxidant, denoted as c2.

[0045] Example 4 Preparation of Antioxidant Same as steps (1) to (2) of Example 1, except that the amount of gallic acid used in step (2) is 2 mol‰ of the dicarboxylic acid, to prepare an antioxidant.

[0046] Test Example 1: Testing of Anti-aging Agents The relative molecular mass of the antioxidants prepared in Examples 1-3 was measured. The specific test results are shown in Table 1. The number-average molecular weight and weight-average molecular weight of the antioxidants increased with the extension of polycondensation time, and the molecular weight distribution also broadened slightly.

[0047] Table 1. M values ​​of the antioxidants prepared in Examples 1-3 w M n and PDI

[0048] Example 5: Preparation of aging-resistant PBAT film Antioxidants a1, a2, and a3 prepared in Example 1 were mixed with PBAT resin particles at a mass ratio of 30:70. The mixtures were then extruded and blown into aging-resistant PBAT films. The blown film extrusion device had a screw processing temperature of 160°C, a die head temperature of 140°C, a screw length-to-diameter ratio of 20:1, and a blow-up ratio of 2:1. Uniform aging-resistant PBAT films with a thickness of approximately 10 μm were obtained and designated A1, A2, and A3, respectively.

[0049] Example 6 Preparation of aging-resistant PBAT film Antioxidant a3 prepared in Example 1 was mixed evenly with PBAT resin particles, and an aging-resistant PBAT film was prepared by extrusion blow molding. The screw processing temperature of the blow molding device was 160°C, the die head temperature was 140°C, the screw length-to-diameter ratio was 20:1, and the blow-up ratio was 2:1. A uniform aging-resistant PBAT film with a thickness of approximately 10 μm was obtained.

[0050] By changing the mass ratio of antioxidant a3 to PBAT resin particles, aging-resistant PBAT films with antioxidant dosages of 10%, 20%, and 30% were prepared, respectively, and denoted as A4, A5, and A6.

[0051] Example 7 Preparation of aging-resistant PBS film Antioxidants b1, b2, and b3 prepared in Example 2 were mixed with PBS resin particles at a mass ratio of 30:70 and then extruded and cast at an extrusion temperature of 170°C, an extrusion speed of 30 r / min, a casting roller speed of 2 r / min, and a die temperature of 170°C. Uniform, age-resistant PBS films with a thickness of approximately 50 μm were obtained and designated as B1, B2, and B3, respectively.

[0052] Example 8 Preparation of aging-resistant PBAT film Antioxidants C1 and C2 prepared in Example 3 were mixed with PBAT resin particles at a mass ratio of 30:70. The mixtures were then extruded and blown into film to prepare aging-resistant PBAT films. The blown film extrusion device had a screw processing temperature of 160°C, a die head temperature of 140°C, a screw length-to-diameter ratio of 20:1, and a blow-up ratio of 2:1. Uniform aging-resistant PBAT films with a thickness of approximately 10 μm were obtained and designated C1 and C2, respectively.

[0053] Comparative Example 1: Preparation of PBAT Thin Film PBAT resin particles were extruded and blown into film to prepare PBAT film. The blown film device had a screw processing temperature of 160℃, a die temperature of 140℃, a screw length-to-diameter ratio of 20:1, and a blow-up ratio of 2:1. A PBAT film with a thickness of approximately 10 μm was obtained.

[0054] Comparative Example 2: Preparation of PBS film PBS resin particles were extruded and cast at an extrusion temperature of 170°C, an extrusion speed of 30 r / min, a casting roller speed of 2 r / min, and a die temperature of 170°C. This yielded a PBS film with a thickness of approximately 50 μm.

[0055] Comparative Example 3: Preparation of PBAT Thin Film Gallic acid and PBAT resin particles were mixed evenly, with gallic acid accounting for 3‰ of the PBAT resin particle mass. An aging-resistant PBAT film was prepared by extrusion blow molding. The blow molding device had a screw processing temperature of 160℃, a die temperature of 140℃, a screw length-to-diameter ratio of 20:1, and a blow-up ratio of 2:1. A modified PBAT film with a thickness of approximately 10 μm was obtained.

[0056] Test Example 2: Testing of Aging-Resistant Biodegradable Films Artificial climate aging experiments were conducted on the films prepared in Examples 5-8 and Comparative Examples 1 and 2 in accordance with GB / T 16422.3-2022, and the mechanical properties of the films during the aging process were tested.

[0057] Compared with Comparative Example 1, the transverse / longitudinal tensile strength and elongation at break of the aging-resistant biodegradable film prepared in Example 5 are as follows: Figure 1 and Figure 2 As shown, the tensile strength of films A1 to A3 all decreased while the elongation at break increased. The plasticizing effect of the antioxidant on PBAT weakened with the increase of its relative molecular mass. After 100 hours of artificial climate aging, the longitudinal tensile strength retention rate of the biodegradable film increased from 51.3% of PBAT to 76.4% of A1, the transverse tensile strength retention rate increased from 44.3% of PBAT to 89.8% of A1, the longitudinal elongation at break retention rate increased from 13.2% of PBAT to 71.1% of A1, and the transverse elongation at break retention rate increased from 18.5% of PBAT to 65.7% of A1. This indicates that the addition of the antioxidant significantly improved the aging resistance of the PBAT film.

[0058] Compared with Comparative Example 1, the transverse / longitudinal tensile strength and elongation at break of the aging-resistant biodegradable film prepared in Example 6 are as follows: Figure 3 and Figure 4As shown, after 100 hours of artificial climate aging, the longitudinal tensile strength retention rate of the biodegradable film can be increased from 51.3% of PBAT to 68.5% of A6, the transverse tensile strength retention rate can be increased from 44.3% of PBAT to 83.8% of A6, the longitudinal elongation at break retention rate can be increased from 13.2% of PBAT to 68.7% of A6, and the transverse elongation at break retention rate can be increased from 18.5% of PBAT to 60.7% of A1. The improvement effect of aging resistance gradually increases with the increase of antioxidant addition.

[0059] Compared with Comparative Example 2, the transverse / longitudinal tensile strength and elongation at break of the aging-resistant biodegradable film prepared in Example 7 are as follows: Figure 5 and Figure 6 As shown, the tensile strength of films B1 to B3 all decreased while the elongation at break increased. The plasticizing effect of the antioxidant on PBS weakened with the increase of its relative molecular mass. After 100 hours of artificial climate aging, the longitudinal tensile strength retention rate of the biodegradable film increased from 64.1% of PBS to 85.3% of B1, the transverse tensile strength retention rate increased from 55.1% of PBS to 76.5% of B1, the longitudinal elongation at break retention rate increased from 35.8% of PBS to 76.8% of B1, and the transverse elongation at break retention rate increased from 41.6% of PBS to 79.5% of B1. This indicates that the addition of the antioxidant significantly improved the aging resistance of the PBS film.

[0060] Compared with Comparative Example 1, the aging-resistant biodegradable film prepared in Example 8 has the following transverse tensile strength and elongation at break: Figure 7 As shown, after 100 hours of artificial climate aging, the tensile strength retention rates of biodegradable films C1 and C2 increased to 90.5% and 81.4%, respectively, and the elongation at break retention rates of biodegradable films C1 and C2 increased to 75.7% and 60.6%, respectively. This indicates that the prepared antioxidant can significantly improve the aging resistance of biodegradable polyester materials.

[0061] 5 mg of the biodegradable film A6 prepared in Example 6 and the film prepared in Comparative Example 3 were immersed in 10 mL of ethanol. The solvent was changed at certain time intervals. The UV-Vis spectra of the resulting immersion solutions were analyzed, and the OD values ​​were determined. 270 nm The release curve of GA in the ethanol solution from the film was obtained by absorbance calculation, as shown below. Figure 8As shown, in the first 12 hours of release, the GA migration in the films of A6 and Comparative Example 3 increased approximately linearly, indicating a rapid release phase. Compared with the 58.9% migration of the film prepared in Comparative Example 3 after 72 hours of immersion, the migration of A6 was significantly reduced, with only 5.0% GA migration after 72 hours of immersion and only 6.6% after 168 hours, fully demonstrating that the antioxidant of this invention has excellent migration resistance.

[0062] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art can make various equivalent substitutions, modifications, or improvements to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The protection scope of the present invention is not limited to the technical solutions described in the above specific embodiments; therefore, the foregoing descriptions are merely preferred options and are not restrictive.

Claims

1. A biodegradable antioxidant comprising a reaction product of a diacid, a diol, and a modifier, wherein the modifier is selected from at least one of an acid compound having a hindered phenolic structure or an ester derivative thereof.

2. The biodegradable antioxidant according to claim 1, characterized in that, The dicarboxylic acid is selected from at least one of aromatic dicarboxylic acids and aliphatic dicarboxylic acids; preferably, the aromatic dicarboxylic acid is terephthalic acid, and / or, the aliphatic dicarboxylic acid is selected from at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, and sebacic acid; and / or, The diol is selected from at least one aliphatic diol, preferably from at least one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptahydrol, octanediol, nonanediol, and decanediol; and / or, The modifier is selected from at least one of gallic acid, linalic acid, ferulic acid, sinapic acid, p-coumaric acid, bisphenolic acid, p-hydroxyphenylpropionic acid, 3,5-di-tert-butyl-4-hydroxyphenylacetic acid, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, or ester derivatives of the above compounds.

3. A method for preparing the biodegradable antioxidant according to claim 1 or 2, comprising the steps of subjecting a component including a diacid and a diol to an esterification reaction and a polycondensation reaction, followed by a reaction with a modifier.

4. The method for preparing the biodegradable antioxidant according to claim 3, characterized in that, The preparation method of the biodegradable antioxidant specifically includes the following steps: (1) The components containing diacids and diols are subjected to esterification reaction under the action of catalyst C1; (2) The product obtained after the esterification reaction in step (1) is subjected to a polycondensation reaction to obtain a hydroxyl-terminated copolyester; (3) The hydroxyl-terminated copolyester obtained in step (2) is reacted with the modifier under the action of catalyst C2 to obtain the biodegradable antioxidant.

5. The method for preparing the biodegradable antioxidant according to claim 4, characterized in that, The molar ratio of the diol to the diacid is (1~2):1, preferably (1.2~1.6):1; and / or, The catalyst C1 and catalyst C2 may be the same or different, and are independently selected from at least one of titanium-based catalysts, germanium-based catalysts, tin-based catalysts, and guanidine catalysts, preferably from at least one of titanium dioxide, titanate catalysts, antimony trioxide, antimony acetate, antimony glycolate, bicyclic guanidine, guanidine acetate, guanidine glycolate, and bicyclic guanidine; and / or, The molar amount of the modifier is 0.005~2.0 mol% of the total molar amount of the diacid, preferably 0.015~0.5 mol%.

6. The method for preparing the biodegradable antioxidant according to claim 4, characterized in that, The esterification reaction is carried out under a protective gas atmosphere at a temperature of 120–220°C for 1–5 hours; and / or, The conditions for the polycondensation reaction are: 220~260℃, pressure <50 Pa, and time 0.2~6 h; and / or, The reaction conditions in step (3) are: carried out under a protective gas atmosphere, at a temperature of 120~220℃, and for a time of 0.2~1h.

7. An aging-resistant biodegradable material comprising a polymer and an antioxidant, wherein the antioxidant is the biodegradable antioxidant as described in claim 1 or 2, or a biodegradable antioxidant obtained by any one of the preparation methods described in claims 3 to 6.

8. The aging-resistant biodegradable material according to claim 7, characterized in that, The polymer is selected from at least one of biodegradable aromatic-aliphatic copolyesters and biodegradable aliphatic copolyesters, preferably from at least one of polybutylene terephthalate, polybutylene terephthalate, polybutylene succinate, and polybutylene succinate; and / or Based on a total weight of 100wt% for the aging-resistant biodegradable material, the antioxidant has a mass percentage content of 5-50wt%, preferably 10-30wt%.

9. A method for preparing the aging-resistant biodegradable material according to claim 7 or 8, comprising the step of mixing components including a polymer and an antioxidant and then performing melt processing.

10. The method for preparing the aging-resistant biodegradable material according to claim 9, characterized in that, The melting process temperature is 120~190℃.

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