Anti-aging biodegradable material as well as preparation method and application thereof

Abstract

The invention discloses an anti-aging biodegradable material as well as a preparation method and application thereof, and belongs to the field of biodegradable high polymer materials. According to the invention, unsaturated acid glycidyl ester, aromatic dibasic acid, aliphatic dibasic acid and aliphatic dihydric alcohol are used as raw materials, and are subjected to ring opening, esterification and condensation polymerization to obtain the anti-aging biodegradable material, and double bonds are introduced into a copolymer main chain, so that the anti-aging performance of the biodegradable material is remarkably improved; the excellent mechanical property and barrier property stability are shown in the aging period; the material has double bonds with reaction activity, can be used for further cross-linking reaction or functionalization reaction, and is used for preparing cross-linked copolyester and functionalized copolyester materials. 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 polymer materials, specifically relating to an aging-resistant biodegradable material, its preparation method, and its application. Background Technology

[0002] In recent years, biodegradable polyester materials have received widespread attention and application in fields such as agricultural mulch films, packaging films, and disposable products. Polybutylene adipate / terephthalate (PBAT) is considered one of the most industrialized biodegradable film materials due to its good toughness, processability, and certain biodegradability. However, in actual use environments, PBAT films still face several key performance bottlenecks: First, under outdoor or storage and transportation environments such as ultraviolet light and heat-humidity cycling, the material is prone to aging processes such as photo-oxidation and chain segment breakage, leading to a decrease in mechanical properties such as tensile strength and elongation at break, affecting the film's service life and reliability. Second, in applications such as packaging preservation and protective covering, films often need to have better water vapor barrier properties to reduce quality degradation or functional decline caused by water vapor penetration, and the water vapor transmission rate (WVTR) of conventional PBAT films still has room for further optimization. Therefore, developing modification technologies that combine aging resistance and water vapor barrier properties and are suitable for PBAT film processing systems has significant engineering application value.

[0003] To improve the aging resistance of PBAT, the commonly used methods in industry and academia are to add small-molecule light stabilizers (such as hindered amines HALS) and UV absorbers. While this method can delay aging to some extent, these small-molecule additives pose a risk of migration and precipitation from the polymer matrix. Additive migration not only leads to the failure of anti-aging function but may also have potential negative impacts on the ecological environment. Another common approach is to introduce unsaturated bond structures. Double bonds can act as structural control units, influencing crystallization and chain segment movement, and can also form a certain degree of micro-crosslinking during processing and use to improve the material's weather resistance and mechanical properties. Patent CN103059282A discloses a biodegradable aliphatic polyester homopolymer containing double bonds. The process involves reacting an aliphatic diacid containing double bonds with an aliphatic diol, followed by polycondensation to obtain a hydroxyl-terminated aliphatic polyester prepolymer, which is then chain-extended to obtain a biodegradable aliphatic polyester homopolymer containing double bonds. Patent CN115124705A discloses a method of polycondensing the esterification products of aromatic diacids and diols with itaconic acid and polyether to obtain a copolymer material with excellent mechanical and thermal properties. The introduced polyether significantly improves the biodegradability of the copolyester, and the unsaturated double bonds can further undergo cross-linking and functionalization reactions. Patent CN119019665A discloses a biodegradable copolyester containing double bonds, which controls the shelf life and degradation rate of the copolyester material by changing the cis-trans content in the double bond structure. However, these traditional methods cannot achieve the "dynamic maintenance" and "synergistic improvement" of material properties throughout its life cycle. Specifically, traditional aging resistance solutions and barrier property improvement solutions are usually independent or even contradictory. When subjected to UV aging, the mechanical and barrier properties of PBAT and its modified materials will decrease synchronously and irreversibly with the breakage of molecular chains. Therefore, there is an urgent need in the field for a new technical approach that can not only improve the aging resistance and barrier properties of PBAT, but also enable these two properties to be synergistically improved during the use of the material. An ideal high-performance PBAT film material should not only retain its anti-aging mechanism under outdoor ultraviolet light, but should also actively transform, so that its barrier properties can be maintained stably or even further improved during the aging process. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing PBAT modification technologies and provide a novel crosslinkable PBAT material with synergistically improved aging resistance and barrier properties, as well as its preparation method. Specifically, the objectives of this invention include: (1) improving the aging resistance and barrier properties of the material by adding monomers containing double bonds during the esterification process to synthesize modified PBAT materials; (2) utilizing the ultraviolet light crosslinking mechanism of double bonds to enable the material to not only maintain mechanical properties during aging but also dynamically maintain barrier properties, breaking through the limitation of all properties deteriorating simultaneously during aging of traditional materials; and (3) the reactive double bonds in the PBAT molecular chain can be used for further crosslinking or functionalization reactions to prepare crosslinked copolyesters and functionalized copolyester materials.

[0005] A first aspect of the present invention is to provide an aging-resistant biodegradable material comprising a reaction product of the following components: unsaturated acid glycidyl ester, diacid, and fatty diol, wherein the diacid comprises aromatic diacid and fatty diacid.

[0006] According to the present invention, in the aging-resistant biodegradable material:

[0007] The unsaturated acid glycidyl ester is selected from at least one of itaconic acid diglycidyl ester, maleic acid glycidyl ester, fumarate glycidyl ester, and dimer fatty acid glycidyl ester; and / or, The aromatic dicarboxylic acid is terephthalic acid; and / or... The fatty dicarboxylic acid is selected from C4-C10 fatty dicarboxylic acids, preferably at least one of succinic acid, glutaric acid, and adipic acid; and / or, The fatty diol is selected from C4-C10 fatty diols, preferably from at least one of 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; and / or, The molar ratio of the diacid to the fatty diol is 1:(1~2), preferably 1:(1~1.5); and / or, The molar ratio of the dicarboxylic acid to the unsaturated acid glycidyl ester is 10:(0.001~5), preferably 10:(0.01~1); and / or, The molar ratio of the aromatic dicarboxylic acid to the fatty dicarboxylic acid is ≤1:1, preferably 1:(1~3); and / or, The dicarboxylic acid may optionally include an unsaturated dicarboxylic acid or its anhydride, preferably at least one of maleic acid, fumaric acid, itaconic acid, dimer fatty acid or its anhydride; more preferably, when it includes an unsaturated dicarboxylic acid or its anhydride, the molar ratio of the unsaturated dicarboxylic acid or its anhydride to the fatty dicarboxylic acid is (0.1~3):100.

[0008] The unsaturated acid glycidyl ester can be obtained from existing commercial products or by existing preparation methods, such as using unsaturated acids (e.g., itaconic acid, maleic acid, fumaric acid, dimer fatty acids, etc.) and epichlorohydrin as raw materials. Specifically, the preparation process can be as follows: the unsaturated acid and epichlorohydrin are heated and reacted under the action of a catalyst and a protective gas atmosphere. After cooling, an alkaline solution is added dropwise, and after stirring and reacting, the mixture is washed and separated to obtain the unsaturated acid glycidyl ester. The molar ratio of unsaturated acid to epichlorohydrin is 1:(1~10). The catalyst is selected from at least one of tetrabutylammonium bromide, benzyltriethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, and trioctylmethylammonium chloride. The amount of catalyst used is 1~5% of the molar amount of unsaturated acid. The heating reaction conditions are: reaction temperature of 90~120℃ and reaction time of 0.2~2h. The alkaline compound in the alkaline solution is selected from at least one of sodium hydroxide and potassium hydroxide. The molar ratio of alkaline compound to unsaturated acid is (1~5):1.

[0009] The second aspect of the present invention is to provide a method for preparing the aging-resistant biodegradable material described in the first aspect of the present invention, comprising: performing a ring-opening reaction on unsaturated acid glycidyl ester and fatty diacid, then adding a component including an aromatic diacid, a fatty diol, and optionally an unsaturated diacid or its anhydride, followed by an esterification reaction and a polycondensation reaction to obtain the aging-resistant biodegradable material; preferably, the method for preparing the aging-resistant biodegradable material comprises: (1) After mixing unsaturated acid glycidyl ester and fatty diacid, the mixture is heated to undergo a ring-opening reaction to obtain a mixed component; the mixed component contains the ring-opening reaction product of unsaturated acid glycidyl ester and fatty diacid and an excess of fatty diacid. (2) The mixed components obtained in step (1), aromatic dicarboxylic acid, fatty diol, optional unsaturated dicarboxylic acid or its anhydride are mixed and heated under the action of a catalyst to esterify the product. (3) The esterified product obtained in step (2) is heated and polycondensed to obtain the aging-resistant biodegradable material.

[0010] According to the present invention, in the preparation method of the aging-resistant biodegradable material: The catalyst is selected from at least one of titanium-based catalysts, antimony-based catalysts, germanium-based catalysts, and tin-based catalysts, preferably from at least one of titanium dioxide, titanate catalysts, antimony trioxide, antimony acetate, antimony glycolate, germanium dioxide and metal complexes, and stannous chloride and metal complexes, more preferably from at least one of titanate catalysts, antimony trioxide, antimony acetate, and antimony glycolate. The titanate catalyst can be a commonly used titanate compound, such as, but not limited to, tetrabutyl titanate and diisopropyl titanate; and / or, There is no particular limitation on the amount of catalyst used; it can be added according to common practices. For example, the amount of catalyst used is 0.5~2 mol% of the total monomer content. The conditions for the ring-opening reaction are: temperature 150~230℃, time 0.2~2 h; and / or, The esterification reaction conditions are: temperature 140~220℃, time 1~5 h; preferably, the esterification reaction includes at least two steps at different temperatures, more preferably, the temperature difference between two adjacent esterification steps is 20~40℃, and the esterification reaction time for each step is 0.5~2 h; and / or, The esterification reaction is carried out under a protective gas atmosphere, which can be commonly used N2 or an inert gas (such as argon); and / or, The conditions for the polycondensation reaction are: temperature 240~260℃, pressure <50 Pa, time 0.2~1.5 h; after the polycondensation reaction, a protective gas (e.g. N2) is introduced to cool the reaction system.

[0011] A third aspect of the present invention is to provide an aging-resistant biodegradable film comprising the aging-resistant biodegradable material described in the first aspect of the present invention or the aging-resistant biodegradable material obtained by the preparation method described in the second aspect of the present invention.

[0012] A fourth aspect of the present invention is to provide a method for preparing the aging-resistant biodegradable film described in the third aspect of the present invention, comprising: blow molding the aging-resistant biodegradable material into a film to obtain the aging-resistant biodegradable film.

[0013] According to the present invention, in the method for preparing the aging-resistant biodegradable film: The blow molding film formation can be achieved using commonly used blow molding equipment and process conditions. For example, the blow molding film formation conditions are: screw temperature of 140–160°C, screw length-to-diameter ratio ≥ 20:1, blow ratio ≥ 2:1; and / or, The thickness of the aging-resistant biodegradable film can be obtained by adjusting the preparation process according to actual needs. For example, the thickness of the aging-resistant biodegradable film is 4~100μm, preferably 8~20μm.

[0014] A fifth aspect of the present invention is to provide a crosslinked copolyester film comprising a mixture and / or reaction product of an aging-resistant biodegradable material, a vulcanizing agent, an accelerator and an activator, wherein the aging-resistant biodegradable material is the aging-resistant biodegradable material described in the first aspect of the present invention or the aging-resistant biodegradable material obtained by the preparation method described in the second aspect of the present invention.

[0015] According to the present invention, in the crosslinked copolyester film: The vulcanizing agent can be a commonly used vulcanizing agent in the prior art, for example, the vulcanizing agent is selected from at least one of sulfur and dicumyl peroxide (DCP); and / or, The accelerator can be a commonly used accelerator in the prior art, for example, the accelerator is selected from at least one of accelerator CZ, accelerator M, and accelerator TMTD; and / or, The activator is selected from at least one of zinc oxide, magnesium oxide, calcium oxide, stearic acid, and diethanolamine; and / or, Based on 100 parts by weight of the aging-resistant biodegradable material, the vulcanizing agent is 0.02 to 1 part, the accelerator is 0.02 to 2 parts, and the activator is 0.1 to 5 parts.

[0016] The sixth aspect of the present invention is to provide a method for preparing the crosslinked copolyester film described in the fifth aspect of the present invention, comprising mixing components including the aging-resistant biodegradable material, vulcanizing agent, accelerator and activator, and then hot-pressing vulcanization to obtain the crosslinked copolyester film.

[0017] According to the present invention, the mixing can be operated on commonly used mixing equipment, such as an internal mixer, etc. Preferably, the mixing conditions are: rotor speed 30~80 r / min, temperature 130~170℃, time 10~20 min; and / or, the hot-press vulcanization can be operated on commonly used vulcanization equipment, preferably, the hot-press vulcanization conditions are: pressure 5~15 MPa, temperature 160~180℃, time 3~15 min.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the esterification process of the synthesis of aging-resistant biodegradable materials, the present invention introduces monomers containing double bonds, which significantly improves the aging resistance and the tensile strength retention rate of the material can be increased by more than 2 times (72 h UV accelerated aging), which is significantly better than unmodified PBAT.

[0019] (2) The aging-resistant biodegradable material prepared by the present invention exhibits excellent barrier performance stability during the aging cycle, breaking through the bottleneck of simultaneous deterioration of various properties of traditional materials.

[0020] (3) The aging-resistant biodegradable material prepared by the present invention has reactive double bonds, which can be used for further crosslinking or functionalization reactions, and can be used to prepare crosslinked copolyesters and functionalized copolyester materials. Attached Figure Description

[0021] Figure 1The tensile strength and retention rate of the aging-resistant biodegradable materials PBAET, PBAIT, and PBSET films prepared in Examples 4, 5, and 6 of this invention, and the PBAT and PBST films prepared in Comparative Examples 3 and 4, before and after aging are compared.

[0022] Figure 2 The elongation at break and retention rate of the aging-resistant biodegradable materials PBAET, PBAIT, and PBSET films prepared in Examples 4, 5, and 6 of this invention, and the PBAT and PBST films prepared in Comparative Examples 3 and 4, are compared before and after aging.

[0023] Figure 3 The water vapor barrier properties of the aging-resistant biodegradable materials PBAET, PBAIT, and PBSET films prepared in Examples 4, 5, and 6 of this invention, and the PBAT and PBST films prepared in Comparative Examples 3 and 4, are compared during the aging process.

[0024] Figure 4 The oxygen barrier properties of the aging-resistant biodegradable materials PBAET, PBAIT, and PBSET films prepared in Examples 4, 5, and 6 of this invention, and the PBAT and PBST films prepared in Comparative Examples 3 and 4, are compared during the aging process.

[0025] Figure 5 The carbon dioxide barrier properties of the aging-resistant biodegradable materials PBAET, PBAIT, and PBSET films prepared in Examples 4, 5, and 6 of this invention, and the PBAT and PBST films prepared in Comparative Examples 3 and 4, are compared during the aging process.

[0026] Figure 6 The tensile strength of the cross-linked copolyester materials cPBAET, cPBAIT, and cPBSET films prepared in Examples 7, 8, and 9 of this invention and the PBAT and PBST films prepared in Comparative Examples 3 and 4 are compared.

[0027] Figure 7 The elongation at break is the cross-linked copolyester materials cPBAET, cPBAIT, and cPBSET films prepared in Examples 7, 8, and 9 of this invention, and the PBAT and PBST films prepared in Comparative Examples 3 and 4.

[0028] Figure 8 The water vapor barrier properties of the cross-linked copolyester film prepared in Example 7 of the present invention and the PBAT film prepared in Comparative Example 3 are compared.

[0029] Figure 9 The oxygen barrier properties of the cross-linked copolyester film prepared in Example 7 of this invention and the PBAT film prepared in Comparative Example 3 are compared.

[0030] Figure 10The carbon dioxide barrier properties of the crosslinked copolyester film prepared in Example 7 of the present invention and the PBAT film prepared in Comparative Example 3 are compared.

[0031] Figure 11 The water vapor barrier properties of the cross-linked copolyester film prepared in Example 8 of the present invention and the PBAT film prepared in Comparative Example 3 are compared.

[0032] Figure 12 The oxygen barrier properties of the cross-linked copolyester film prepared in Example 8 of the present invention and the PBAT film prepared in Comparative Example 3 are compared.

[0033] Figure 13 The carbon dioxide barrier properties of the crosslinked copolyester film prepared in Example 8 of this invention and the PBAT film prepared in Comparative Example 3 are compared. Detailed Implementation

[0034] 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.

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The raw materials used in the following embodiments of the present invention are sourced from the following sources: Terephthalic acid, adipic acid, 1,4-butanediol, itaconic acid, tetrabutyl titanate, epichlorohydrin, bromocyclotetrabutylamine, and antimony trioxide are produced by Aladdin Biochemical Technology Co., Ltd. Sulfur, zinc oxide, accelerator M (2-mercaptobenzothiazide) and accelerator CZ (N-cyclohexyl-2-benzothiazolium sulfenamide) are all commercially available.

[0041] The product characterization method used in this invention is 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℃.

[0042] Tensile property test: conducted according to GB / T 1040.3-2006 on a SANS CMT6104 instrument, using type 2 specimens, with a tensile speed of 100 mm / min.

[0043] Artificial weathering test: The artificial weathering performance of the thin film was tested using an Atlas test chamber (Ci 4000) equipped with a 6500 W xenon lamp, according to GB / T 16422.2-2014. The blackboard temperature (BPT) of the dark chamber was 65℃, and the relative humidity was 50%. A 2-hour exposure cycle was used, with each cycle consisting of 108 minutes of UV radiation and 12 minutes of simultaneous water spray and UV radiation. The incident light intensity was 0.55 W / m². 2 The wavelength is 340 nm.

[0044] Water vapor barrier performance test: conducted according to GB / T 1037-2021 on a Labthink C360M instrument, at a temperature of 23℃ and a relative humidity of 50%.

[0045] Gas barrier performance test: conducted according to GB / T 1038.1-2022 on a Labthink PERME VAC-V2 instrument at a temperature of 23℃ and a gas purity of ≥99.9%.

[0046] Example 1: Preparation of aging-resistant biodegradable materials The preparation of the aging-resistant biodegradable material PBAET includes the following steps: (1) Preparation of itaconic acid diglycidyl ester: Itaconic acid, epichlorohydrin and tetrabutylamine bromide were mixed in a molar ratio of 100:500:2 and reacted at 105℃ for 30 min under N2 atmosphere; cooled to 30℃ and 2.27 times the molar amount of sodium hydroxide (12.5 M sodium hydroxide aqueous solution) of itaconic acid was added dropwise, and stirred for 3 h until the reaction was completed; the product was washed 5 times with deionized water, the organic phase was separated and impurities were removed by rotary evaporator to obtain itaconic acid diglycidyl ester.

[0047] (2) Ring-opening reaction: Itaconic acid diglycidyl ester (EIA) and adipic acid (AA) were mixed in a molar ratio of 0.4:100 and reacted at 180°C for 30 min under N2 atmosphere to obtain a mixed component, denoted as EIA-AA.

[0048] (3) Esterification reaction: Terephthalic acid, EIA-AA, 1,4-butanediol and tetrabutyl titanate are mixed in a molar ratio of 100:100 (based on the AA added in step (2)): 280:3. The reaction is carried out under N2 atmosphere at 160℃ for 1 h and 200℃ for 2 h until 95% theoretical water is collected.

[0049] (4) Polycondensation reaction: The system pressure is controlled to be <50 Pa, and the temperature is slowly raised to 260℃ within 1 h. When the climbing effect occurs, N2 is introduced to reduce the system to room temperature, and the aging-resistant biodegradable material PBAET is obtained.

[0050] Using the preparation process of steps (1) to (4) above, the amount of EIA was changed to prepare copolyesters with molar ratios of EIA and AA of 0.4:100, 0.6:100, 0.8:100 and 1:100 respectively. The resulting aging-resistant biodegradable materials PBAET were denoted as a1, a2, a3 and a4 respectively.

[0051] Example 2 Preparation of aging-resistant biodegradable materials The preparation of the aging-resistant biodegradable material PBAIT includes the following steps: (1) Preparation of itaconic acid diglycidyl ester: Itaconic acid, epichlorohydrin and tetrabutylamine bromide were mixed in a molar ratio of 100:500:2 and reacted at 105℃ for 30 min under N2 atmosphere; cooled to 30℃ and 2.27 times the molar amount of sodium hydroxide (12.5 M sodium hydroxide aqueous solution) of itaconic acid were added dropwise, and stirred for 3 h until the reaction was completed; the product was washed 5 times with deionized water, the organic phase was separated and impurities were removed by rotary evaporator to obtain itaconic acid diglycidyl ester.

[0052] (2) Ring-opening reaction: Itaconic acid diglycidyl ester (EIA) and adipic acid (AA) were mixed in a molar ratio of 0.6:100 and reacted at 180°C for 30 min under N2 atmosphere to obtain a mixed component, denoted as EIA-AA.

[0053] (3) Esterification reaction: Terephthalic acid, EIA-AA, itaconic acid, 1,4-butanediol and tetrabutyl titanate were mixed in a molar ratio of 100: 100: 0.4: 280: 3. The reaction was carried out under N2 atmosphere at 160℃ for 1 h, 180℃ for 1 h, and 200℃ for 2 h until 95% theoretical water was collected.

[0054] (4) Polycondensation reaction: The system pressure is controlled to be <50 Pa, and the temperature is slowly raised to 260℃ within 1 h. When the climbing effect occurs, N2 is introduced to lower the system to room temperature, and the aging-resistant biodegradable material PBAIT is obtained.

[0055] Using the preparation process of steps (1) to (4) above, the amount of itaconic acid was changed, and the molar ratio of itaconic acid to 1,4-butanediol was 0.4:280, 0.6:280, 0.8:280 and 1:280, respectively. The resulting aging-resistant biodegradable materials PBAIT were denoted as b1, b2, b3 and b4.

[0056] Example 3 Preparation of aging-resistant biodegradable materials The preparation of the aging-resistant biodegradable material PBSET includes the following steps: (1) Preparation of itaconic acid diglycidyl ester: Itaconic acid, epichlorohydrin and tetrabutylamine bromide were mixed in a molar ratio of 100:500:2 and reacted at 105℃ for 30 min under N2 atmosphere; cooled to 30℃ and 2.27 times the molar amount of sodium hydroxide (12.5 M sodium hydroxide aqueous solution) of itaconic acid were added dropwise, and stirred for 3 h until the reaction was completed; the product was washed 5 times with deionized water, the organic phase was separated and impurities were removed by rotary evaporator to obtain itaconic acid diglycidyl ester.

[0057] (2) Ring-opening reaction: Itaconic acid diglycidyl ester (EIA) and succinic acid (SA) were mixed in a molar ratio of 0.8:100 and reacted at 190°C for 30 min under N2 atmosphere to obtain a mixed component, denoted as EIA-SA.

[0058] (3) Esterification reaction: Terephthalic acid, EIA-SA, 1,4-butanediol and tetrabutyl titanate are mixed in a molar ratio of 100:100:280:3. The reaction is carried out under N2 atmosphere at 160℃ for 1 h and 200℃ for 2 h until 95% theoretical water is collected.

[0059] (4) Polycondensation reaction: The system pressure is controlled to be <50 Pa, and the temperature is slowly raised to 260℃ within 1 h. When the climbing effect occurs, N2 is introduced to lower the system to room temperature, and the aging-resistant biodegradable material PBSET is obtained.

[0060] Comparative Example 1: Preparation of PBAT material The preparation of PBAT material includes the following steps: (1) Esterification reaction: Adipic acid, terephthalic acid, 1,4-butanediol and tetrabutyl titanate are mixed in a molar ratio of 100:100:280:3. The reaction is carried out under N2 atmosphere at 160℃ for 1 h, 180℃ for 1 h, and 200℃ for 2 h until 95% theoretical water is collected.

[0061] (2) Polycondensation reaction: The system pressure is controlled to be <50 Pa, and the temperature is slowly raised to 260℃ within 1 h. When the climbing effect occurs, N2 is introduced to lower the system to room temperature, and the biodegradable material PBAT is obtained.

[0062] Comparative Example 2: Preparation of PBST material The preparation of PBST material includes the following steps: (1) Esterification reaction: Succinic acid, terephthalic acid, 1,4-butanediol and tetrabutyl titanate are mixed in a molar ratio of 100:100:280:3. The reaction is carried out under N2 atmosphere at 160℃ for 1 h, 180℃ for 1 h, and 200℃ for 2 h until 95% theoretical water is collected.

[0063] (2) Polycondensation reaction: The system pressure is controlled to be <50 Pa, and the temperature is slowly raised to 260℃ within 1 h. When the climbing effect occurs, N2 is introduced to lower the system to room temperature, and the biodegradable material PBST is obtained.

[0064] Test Example 1: Testing of Aging-Resistant Biodegradable Materials The relative molecular mass of the biodegradable materials prepared in Examples 1-3 and Comparative Examples 1-2 was determined, and the specific results are shown in Table 1. Compared with the PBAT material in Comparative Example 1 without the introduction of monomers containing double bonds, the weight-average molecular weight of the biodegradable materials PBAET and PBAIT prepared in Examples 1 and 2 was significantly increased, while the number-average molecular weight did not change significantly. The weight-average molecular weight and molecular weight distribution increased with the increase of the amount of monomers containing double bonds. Compared with the PBST material prepared in Comparative Example 2, the weight-average molecular weight of the biodegradable material PBSET prepared in Example 3 was increased, the number-average molecular weight was decreased, and the molecular weight distribution was broadened.

[0065] Table 1. M of the biodegradable materials prepared in Examples 1-3 and Comparative Examples 1-2 w M n and PDI

[0066] Example 4: Preparation of aging-resistant biodegradable films The aging-resistant biodegradable material PBAET (a1~a4) prepared in Example 1 was subjected to low-temperature crushing, and then PBAET films were prepared by extrusion blown film. The screw processing temperature of the blown film 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. Uniform PBAET films with a thickness of approximately 10 μm were obtained and designated as A1, A2, A3, and A4, respectively.

[0067] Example 5: Preparation of aging-resistant biodegradable films Same as Example 4, except that the aging-resistant biodegradable material used is PBAIT (b1~b4) prepared in Example 2, and the resulting aging-resistant biodegradable films are respectively denoted as B1, B2, B3 and B4.

[0068] Example 6 Preparation of aging-resistant biodegradable films Same as Example 4, except that the aging-resistant biodegradable material used is PBSET prepared in Example 3.

[0069] Comparative Example 3 Same as Example 4, except that the biodegradable material used is PBAT prepared in Comparative Example 1.

[0070] Comparative Example 4 Same as Example 4, except that the biodegradable material used is PBST prepared in Comparative Example 2.

[0071] Test Example 2: Testing of Aging-Resistant Biodegradable Films The biodegradable films prepared in Examples 4, 5, and 6, and Comparative Examples 3 and 4, were subjected to artificial climate aging experiments. The artificial climate aging time was set to 100 hours, and samples were taken out for tensile property testing after 24 hours, 48 ​​hours, and 72 hours of aging. Figures 1-2 As shown, the tensile strength and retention rate, and elongation at break and retention rate of the biodegradable films prepared in Examples 4, 5, 6 and Comparative Examples 3, 4 before and after aging are compared. The tensile strength of the PBAT film prepared in Comparative Example 3 decreased to 8.4 MPa and the elongation at break decreased to 125.1% after 72 hours of UV aging. The tensile strength of the PBAET film prepared in Example 4 was improved compared to pure PBAT. With lower amounts of monomer EIA and lower double bond content (A1 and A2), the tensile strength and elongation at break decreased with increasing aging time, but the retention rate of tensile strength and elongation at break was higher than that of the PBAT film. With increasing double bond content, the tensile strength of A3 and A4 films increased after aging for 48 h and 24 h, respectively, while the elongation at break increased after 24 h of aging and then gradually decreased with further aging. The tensile strength of the PBAET film prepared in Example 5 was improved compared to pure PBAT. With lower amounts of monomer itaconic acid and lower double bond content (B1), the tensile strength and elongation at break decreased with increasing aging time, but the retention rate of tensile strength and elongation at break was higher than that of the PBAT film. With increasing double bond content, the tensile strength of B2, B3, and B4 films increased after aging for 72 h, 48 h, and 24 h, respectively, while the elongation at break increased after aging for 24 h of aging. After a period of aging, the tensile strength initially increased but then gradually decreased with increasing aging time. Specifically, the B2 film retained over 90% of its tensile strength and elongation at break after 72 hours of aging. Compared to Comparative Example 4, the PBSET film prepared in Example 6 showed a slight increase in tensile strength and a significant improvement in aging resistance.

[0072] like Figures 3-5As shown, the water vapor transmission coefficient (WVP) of the PBAT and PBST films prepared in Comparative Examples 3 and 4 gradually increased with aging time, while their water vapor barrier performance continuously decreased. Compared with Comparative Example 3, the water vapor transmission coefficient (WVP), oxygen transmission coefficient (OP), and carbon dioxide transmission coefficient (CDP) of the PBST film prepared in Example 4 all decreased. When the monomer EIA content was low and the double bond content was low (A1 and A2), the water vapor transmission coefficient, oxygen transmission coefficient, and carbon dioxide transmission coefficient gradually increased with the increase of aging time. With the increase of double bond content, the A3 and A4 films gradually crosslinked during the aging process, and their barrier performance decreased more slowly and eventually leveled off. Compared to Comparative Example 3, the water vapor permeability, oxygen permeability, and carbon dioxide permeability of the PBAIT film prepared in Example 5 all decreased. With lower amounts of itaconic acid monomer and lower double bond content (B1), the water vapor permeability, oxygen permeability, and carbon dioxide permeability gradually increased with increasing aging time. With increasing double bond content, B2 and B3 films gradually crosslinked during aging, and their barrier properties decreased more slowly and eventually leveled off. With further increases in double bond content, the water vapor permeability, oxygen permeability, and carbon dioxide permeability of the B4 film showed an increasing trend with increasing aging time. Compared to Comparative Example 4, the water vapor permeability, oxygen permeability, and carbon dioxide permeability of the PBSET film prepared in Example 6 all decreased; and its barrier properties decreased more slowly with increasing aging time. This indicates that the introduction of monomers containing double bonds has a significant effect on improving the aging resistance and barrier properties of biodegradable materials, demonstrating a "synergistic improvement" between barrier properties and aging resistance, and the improvement effect is related to the amount of double bonds introduced.

[0073] Example 7 Preparation of crosslinked copolyester cPBAET film The aging-resistant biodegradable materials PBAET (a1~a4) prepared in Example 1 were respectively mixed with a 0.25 phr vulcanization system and then hot-pressed to form cross-linked copolyester cPBAET films with a thickness of 10 μm. The vulcanization system used consisted of sulfur, accelerator CZ, accelerator M, and zinc oxide mixed in a mass ratio of 1.0:1.0:0.7:5.0. The specific conditions for mixing were a rotor speed of 70 r / min, a temperature of 150℃, and a time of 15 min; the specific conditions for hot-pressing were a pressure of 10 MPa, a temperature of 160℃, and a time of 5 min. The cross-linked copolyester cPBAET films prepared from the aging-resistant biodegradable materials a1, a2, a3, and a4 were designated as C1, C2, C3, and C4, respectively.

[0074] Example 8 Preparation of crosslinked copolyester cPBAIT film Same as Example 7, except that the aging-resistant biodegradable material used is PBAIT (b1~b4) prepared in Example 2. The cross-linked copolyester cPBAIT films prepared from the aging-resistant biodegradable materials b1, b2, b3 and b4 are respectively designated as D1, D2, D3 and D4.

[0075] Example 9 Preparation of crosslinked copolyester cPBSET film Same as Example 7, except that the aging-resistant biodegradable material used is PBSET prepared in Example 3, and the resulting cross-linked copolyester cPBSET film is prepared.

[0076] Test Example 3: Testing of Crosslinked Copolyester Films The crosslinked copolyester films prepared in Examples 7, 8, and 9, and the PBAT and PBST films prepared in Comparative Examples 3 and 4, were subjected to Soxhlet extraction using chloroform as the solvent, at a temperature of 60°C, and for 4 hours. The gel content of the films was calculated. The gel content of the films prepared in Comparative Examples 3 and 4 was 0. The gel contents of C1, C2, C3, and C4 of the crosslinked copolyester cPBAET film prepared in Example 7 were 0.3%, 1.0%, 3.2%, and 6.1%, respectively. The gel contents of D1, D2, D3, and D4 of the crosslinked copolyester cPBAET film prepared in Example 8 were 0.5%, 1.3%, 4.2%, and 7.6%, respectively. The gel content of the crosslinked copolyester cPBSET film prepared in Example 9 was 3.7%. The gel content of the crosslinked copolyester films increased with the increase of double bond introduction, indicating that the degree of crosslinking of the film increased with the increase of double bond introduction.

[0077] like Figures 6-7 As shown, compared with Comparative Example 3, the tensile strength and elongation at break of the crosslinked copolyester films prepared in Examples 7 and 8 with moderate crosslinking are significantly improved. The tensile strength and elongation at break of the crosslinked copolyester cPBAET film C2 prepared in Example 7 can be increased to 20.7 MPa and 879%, respectively, which are 19.7% and 20.7% higher than the PBAT film prepared in Comparative Example 3. The tensile strength and elongation at break of the crosslinked copolyester cPBAET film D2 prepared in Example 8 can be increased to 21.4 MPa and 938%, respectively, which are 23.7% and 28.8% higher than the PBAT film prepared in Comparative Example 3. Compared with Comparative Example 4, the tensile strength and elongation at break of the crosslinked copolyester cPBSET film prepared in Example 9 can be increased by 14.4% and 19.9%, respectively. The micro-crosslinked network formed by moderate crosslinking can effectively transfer stress and restrict the slippage of small molecules, thereby significantly improving tensile strength, while retaining the degree of freedom of chain segment movement, thus improving elongation at break. As the degree of crosslinking further increases, the tensile properties of the crosslinked copolyester films prepared in Examples 7, 8, and 9 gradually decrease.

[0078] like Figures 8-13 As shown, compared to Comparative Example 3, the water vapor barrier, oxygen barrier, and carbon dioxide barrier properties of the crosslinked copolyester films prepared in Examples 7 and 8 with moderate crosslinking were significantly reduced. In the figure, BIFp represents the barrier improvement factor, which is the ratio of the permeability coefficient of the copolyester film in Comparative Example 3 to the permeability coefficient of the crosslinked copolyester film in Example 7 or Example 8. The water vapor permeability of Example 7 was reduced from 48.4 × 10⁻⁶ in Comparative Example 3. -14 g cm / cm 2 s Pa decreased to a maximum of 25.1 × 10 -14 g cm / cm 2 s In Example 8, the oxygen permeability decreased by a maximum of 0.27 Barrer from 0.56 Barrer in Comparative Example 3, and the carbon dioxide permeability decreased by a maximum of 1.94 Barrer from 5.3 Barrer in Comparative Example 3; the water vapor permeability in Example 8 decreased from 48.4 × 10⁻⁶ Barrer in Comparative Example 3. -14 g cm / cm 2 s Pa decreased to a maximum of 24.4 × 10 -14 g cm / cm 2 s At Pa, the oxygen permeability decreased by a maximum of 0.23 Barrer from 0.56 Barrer in Comparative Example 3, and the carbon dioxide permeability decreased by a maximum of 2.37 Barrer from 5.3 Barrer in Comparative Example 3. When the degree of cross-linking was further increased, the molecular weight distribution broadened and the aggregate structure changed, resulting in more diffusion paths for gas molecules and a slight decrease in barrier performance, but it was still better than pure PBAT.

[0079] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. An aging-resistant biodegradable material comprising the reaction product of the following components: glycidyl unsaturated acid, diacid, and fatty diol, wherein the diacid comprises aromatic diacid and fatty diacid.

2. The aging-resistant biodegradable material according to claim 1, characterized in that, The unsaturated acid glycidyl ester is selected from at least one of itaconic acid diglycidyl ester, maleic acid glycidyl ester, fumarate glycidyl ester, and dimer fatty acid glycidyl ester; and / or, The aromatic dicarboxylic acid is terephthalic acid; and / or... The fatty dicarboxylic acid is selected from C4-C10 fatty dicarboxylic acids, preferably at least one of succinic acid, glutaric acid, and adipic acid; and / or, The fatty diol is selected from C4-C10 fatty diols, preferably from at least one of 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; and / or, The molar ratio of the diacid to the fatty diol is 1:(1~2), preferably 1:(1~1.5); and / or, The molar ratio of the dicarboxylic acid to the unsaturated acid glycidyl ester is 10:(0.001~5), preferably 10:(0.01~1); and / or, The molar ratio of the aromatic dicarboxylic acid to the fatty dicarboxylic acid is ≤1:1, preferably 1:(1~3); and / or, The dicarboxylic acid may optionally include an unsaturated dicarboxylic acid or its anhydride, preferably at least one of maleic acid, fumaric acid, itaconic acid, dimer fatty acid or its anhydride; more preferably, when it includes an unsaturated dicarboxylic acid or its anhydride, the molar ratio of the unsaturated dicarboxylic acid or its anhydride to the fatty dicarboxylic acid is (0.1~3):

100.

3. A method for preparing the aging-resistant biodegradable material according to claim 1 or 2, comprising: After a ring-opening reaction of unsaturated acid glycidyl ester and fatty diacid, a component including aromatic diacid, fatty diol, and optionally unsaturated diacid or its anhydride is added, followed by esterification and polycondensation reactions to obtain the aging-resistant biodegradable material; preferably, the preparation method of the aging-resistant biodegradable material includes: (1) After mixing unsaturated acid glycidyl ester and fatty dicarboxylic acid, the mixture is heated to open the ring and obtain a mixed component; (2) The mixed components obtained in step (1), aromatic dicarboxylic acid, fatty diol, optional unsaturated dicarboxylic acid or its anhydride are mixed and heated under the action of a catalyst to esterify the product. (3) The esterified product obtained in step (2) is heated and polycondensed to obtain the aging-resistant biodegradable material.

4. The method for preparing the aging-resistant biodegradable material according to claim 3, characterized in that, The catalyst is selected from at least one of titanium-based catalysts, antimony-based catalysts, germanium-based catalysts, and tin-based catalysts, preferably from at least one of titanium dioxide, titanate catalysts, antimony trioxide, antimony acetate, antimony glycolate, germanium dioxide and metal complexes, and stannous chloride and metal complexes, more preferably from at least one of titanate catalysts, antimony trioxide, antimony acetate, and antimony glycolate; and / or, The conditions for the ring-opening reaction are: temperature 150~230℃, time 0.2~2 h; and / or, The conditions for the esterification reaction are: temperature 140~220℃, time 1~5 h; and / or, The esterification reaction is carried out under a protective gas atmosphere; and / or, The conditions for the polycondensation reaction are: temperature 240~260℃, pressure <50 Pa, and time 0.2~1.5 h.

5. An aging-resistant biodegradable film comprising the aging-resistant biodegradable material as described in claim 1 or 2, or the aging-resistant biodegradable material obtained by the preparation method described in claim 3 or 4.

6. A method for preparing the aging-resistant biodegradable film according to claim 5, comprising: The aging-resistant biodegradable material is blown into a film to obtain the aging-resistant biodegradable film.

7. The method for preparing the aging-resistant biodegradable film according to claim 6, characterized in that, The conditions for blow molding film formation are: screw temperature 140–160°C, screw length-to-diameter ratio ≥ 20:1, blow ratio ≥ 2:1; and / or, The thickness of the aging-resistant biodegradable film is 4~100μm, preferably 8~20μm.

8. A crosslinked copolyester film comprising a mixture and / or reaction product of an aging-resistant biodegradable material, a vulcanizing agent, an accelerator and an activator, wherein the aging-resistant biodegradable material is the aging-resistant biodegradable material according to claim 1 or 2 or the aging-resistant biodegradable material obtained by the preparation method according to claim 3 or 4.

9. The crosslinked copolyester film according to claim 8, characterized in that, The vulcanizing agent is selected from at least one of sulfur and dicumyl peroxide; and / or, The accelerator is selected from at least one of accelerator CZ, accelerator M, and accelerator TMTD; and / or, The activator is selected from at least one of zinc oxide, magnesium oxide, calcium oxide, stearic acid, and diethanolamine; and / or, Based on 100 parts by weight of the aging-resistant biodegradable material, the vulcanizing agent is 0.02 to 1 part, the accelerator is 0.02 to 2 parts, and the activator is 0.1 to 5 parts.

10. A method for preparing the crosslinked copolyester film according to claim 8 or 9, comprising mixing components including the aging-resistant biodegradable material, vulcanizing agent, accelerator and activator, and then hot-pressing vulcanization to obtain the crosslinked copolyester film; preferably, the mixing conditions are: rotor speed 30~80 r / min, temperature 130~170℃, time 10~20 min, and / or, the hot-pressing vulcanization conditions are: pressure 5~15 MPa, temperature 160~180℃, time 3~15 min.

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