Biodegradable polyester composite material and application thereof

Abstract

The invention provides a biodegradable polyester composite material and application thereof, and the biodegradable polyester composite material comprises the following components in parts by weight: 63-95 parts of biodegradable polyester, 2-10 parts of polylactic acid, 1-10 parts of polycarbonate polyurethane, 1-12 parts of an inorganic filler and 1-5 parts of cellulose acetate. After the biodegradable polyester is boiled in water at 95 DEG C for 24 hours, the carboxyl content is 10-50 mol / t. According to the biodegradable polyester composite material, the specific biodegradable polyester is compounded with the polylactic acid, the polycarbonate type polyurethane, the cellulose acetate and the inorganic filler, and a membrane material prepared from the biodegradable polyester composite material has relatively low water vapor permeability.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable materials technology, specifically relating to a biodegradable polyester composite material and its applications. Background Technology

[0002] Biodegradable mulch films are a type of plastic mulch film that can degrade under natural environmental conditions through the action of microorganisms. After microorganisms such as bacteria, fungi, and actinomycetes erode the plastic film, their cell growth causes the polymer components to hydrolyze, ionize, or protonate, resulting in mechanical damage and the film breaking down into oligomer fragments. Enzymes secreted by fungi or bacteria decompose or oxidize water-soluble polymers into water-soluble fragments, generating new small molecule compounds, until finally decomposing into CO2 and H2O. Among these biodegradable mulch films, biodegradable polyester mulch films are the most common and have received widespread attention.

[0003] However, biodegradable mulch films require low water vapor permeability in some applications, but ordinary biodegradable polyester materials have high water vapor permeability, which limits their application.

[0004] Therefore, developing a biodegradable polyester composite material with low water vapor permeability is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a biodegradable polyester composite material and its applications. The membrane material made from the biodegradable polyester composite material exhibits low water vapor permeability.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a biodegradable polyester composite material, wherein, by weight, the biodegradable polyester composite material comprises 63-95 parts of biodegradable polyester, 2-10 parts of polylactic acid, 1-10 parts of polycarbonate-type polyurethane, 1-12 parts of inorganic filler and 1-5 parts of cellulose acetate; the carboxyl content of the biodegradable polyester after boiling in water at 95°C for 24 hours is 10-50 mol / t.

[0007] In this invention, controlling the carboxyl content of the biodegradable polyester within a specific range after boiling in water at 95°C for 24 hours results in better stability of the melt-blended material and better preservation of the molecular chains during processing, thereby helping to reduce water vapor permeability. Excessively high carboxyl content after boiling indicates that water molecules can enter the material under heat, leading to molecular chain breakage and the formation of terminal carboxyl groups. This will also cause molecular chain breakage during melt shear blending of the resin and inorganic fillers in a twin-screw extruder. The breakage of molecular chains weakens chain entanglement, increases the gaps between polyester molecular chains, and facilitates water vapor permeation. Conversely, excessively low carboxyl content after boiling indicates a very dense internal microstructure of the polyester, with strong molecular chain entanglement or crystallization. However, excessively strong entanglement and crystallization are detrimental to compatibility with PLA and filler encapsulation, leading to microscopic defects at the phase interface between different components, which also contributes to water vapor permeation. By incorporating polycarbonate-type polyurethane, the soft segment, composed of polycarbonate diol, exhibits higher rigidity and density compared to other types of polyurethane, such as polyether-type polyurethane. Furthermore, the carbonate bond (-O-CO-O-) is more polar than polyether, forming a stronger hydrogen bond network with the urethane bond in the hard segment. This results in a more compact chain segment and smaller free volume, effectively restricting the penetration and diffusion of water molecules. Additionally, polycarbonate exhibits better hydrolysis resistance than polyester and has lower intrinsic hydrophilicity, further enhancing its ability to inhibit water molecule penetration and diffusion. Further combination with cellulose acetate, which possesses numerous hydroxyl and polar groups, enables the formation of abundant, strong, and ordered hydrogen bonds with biodegradable polyester, polylactic acid, and polycarbonate-type polyurethane. This dense physical cross-linking network significantly restricts the movement of polymer chain segments, resulting in a more compact molecular chain stack and a substantial improvement in barrier properties. Therefore, by using biodegradable polyester with a carboxyl content within a specific range after boiling in water, and compounding it with polylactic acid, polycarbonate-type polyurethane, inorganic fillers, and cellulose acetate in specific amounts, the membrane prepared from the biodegradable polyester composite material has a low water vapor permeability.

[0008] In this invention, 63 to 95 parts of biodegradable polyester can be, for example, 64 parts, 66 parts, 68 parts, 70 parts, 72 parts, 74 parts, 76 parts, 78 parts, 80 parts, 82 parts, 84 parts, 86 parts, 88 parts, 90 parts, 92 parts, 94 parts, or any range of the above values.

[0009] In this invention, the biodegradable polyester composite material contains ≥70% by mass, preferably 75-90%, and more preferably 81-87%.

[0010] In this invention, the weight-average molecular weight (Mw) of the biodegradable polyester is 50,000 to 200,000 Da; it can be obtained by gel permeation chromatography.

[0011] In this invention, 2 to 10 parts of polylactic acid, for example, can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts or any of the above values, preferably 5.5 to 7.5 parts.

[0012] In this invention, the mass percentage of polylactic acid in the biodegradable polyester composite material is ≤10%, preferably 2~9%, and more preferably 5~7%.

[0013] In this invention, the melt index of the polylactic acid is 2~50g / 10min at 190℃ and 2.16kg.

[0014] In this invention, 1 to 10 parts of polycarbonate-type polyurethane can be, for example, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, 5.0 parts, 5.5 parts, 6.0 parts, 6.5 parts, 7.0 parts, 7.5 parts, 8.0 parts, 8.5 parts, 9.0 parts, 9.5 parts, or any range of the above values.

[0015] In this invention, at 190°C and 2.16 kg, the melt index of the polycarbonate-type polyurethane is 2~30 g / 10min.

[0016] In this invention, the melt flow index can be measured with reference to the ISO 1133-1:2022 standard.

[0017] In this invention, the mass percentage of polycarbonate-type polyurethane in the biodegradable polyester composite material is 1-10%, preferably 1.3-9.1%.

[0018] In this invention, 1 to 12 parts of inorganic filler can be, for example, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, 5.0 parts, 5.5 parts, 6.0 parts, 6.5 parts, 7.0 parts, 7.5 parts, 8.0 parts, 8.5 parts, 9.0 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, or any range of the above values.

[0019] In this invention, 1 to 5 parts of cellulose acetate can be, for example, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3.0 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts, 4.0 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, or any range of the above values.

[0020] In this invention, the mass percentage of cellulose acetate in the biodegradable polyester composite material is 1-5%, preferably 1.3-4.6%.

[0021] In this invention, the carboxyl content of the biodegradable polyester after boiling in water at 95°C for 24 hours is 10~50 mol / t, for example, it can be 10 mol / t, 12 mol / t, 14 mol / t, 16 mol / t, 18 mol / t, 20 mol / t, 22 mol / t, 24 mol / t, 26 mol / t, 28 mol / t, 30 mol / t, 32 mol / t, 34 mol / t, 35 mol / t, 38 mol / t, 40 mol / t, 42 mol / t, 44 mol / t, 46 mol / t, 48 mol / t or any of the above values, preferably 12~40 mol / t, more preferably 14~35 mol / t.

[0022] Preferably, the biodegradable polyester comprises an aliphatic-aromatic copolyester.

[0023] In this invention, the aliphatic-aromatic copolyester comprises diacid residues and diol residues; the diacid residues comprise aromatic diacid residues and / or aliphatic diacid residues, preferably aromatic diacid residues comprise terephthalic acid residues and / or furanyl dicarboxylic acid residues; preferably aliphatic diacid residues comprise at least one of adipic acid residues, succinic acid residues, azelaic acid residues, sebacic acid residues, or brassic acid residues; the diol residues preferably comprise propylene glycol residues and / or butanediol residues. The molar percentage of aromatic diacid residues in the diacid residues is 5-90 mol%, preferably 20-70 mol%.

[0024] In this invention, the term "residue" refers to a structural unit introduced into the polyester molecular chain by a related monomer through a polycondensation reaction. Specifically, aromatic diacids and / or their derivatives are introduced into the polyester molecular chain through a polycondensation reaction to form aromatic diacid residues; aliphatic diacids and / or their derivatives are introduced into the molecular chain through a polycondensation reaction to form aliphatic diacid residues; the aromatic diacids include, but are not limited to, terephthalic acid, furanyl dicarboxylic acid, etc.; the aliphatic diacids include, but are not limited to, adipic acid, azelaic acid, sebacic acid, succinic acid, brassic acid, etc.; the derivatives include esters of aromatic diacids or esters of aliphatic diacids, such as diC1-C10 alkyl esters of aromatic diacids, diC1-C10 alkyl esters of aliphatic diacids, etc., wherein diC1-C10 alkyl esters exemplarily include, but are not limited to, dimethyl ester, diethyl ester, di-n-propyl ester, di-n-butyl ester, di-n-hexyl ester, di-n-decyl ester, etc.

[0025] Preferably, the aliphatic-aromatic copolyester comprises any one or a combination of at least two of polybutylene adipate terephthalate (PBAT), polybutylene sebacic acid terephthalate (PBSeT), and polybutylene terephthalate succinate (PBST).

[0026] In this invention, the biodegradable polyester can be obtained commercially or prepared using conventional methods. Exemplarily, the method includes: reacting a diacid with a diol at 182-188°C for 3.5-4.5 h to obtain an esterification product; reacting the esterification product at 245-255°C and 320-370 Pa for 2.5-9.5 h in the presence of a catalyst to obtain a polycondensation product; mixing the polycondensation product with a crosslinking agent and continuing the reaction at 245-255°C and 320-370 Pa for 0 h. The biodegradable polyester is obtained by incubation for 8-8.5 hours; the molar ratio of the diacid to the diol is (1.2-1.4):1; the mass of the catalyst is 0.25-0.32% of the mass of the diacid; the catalyst includes tetrabutyl titanate or a composite catalyst formed by tetrabutyl titanate and zinc isooctanoate in a mass ratio of 2:1; the mass of the crosslinking agent is 0.072-0.077% of the mass of the diacid; the crosslinking agent includes trihydroxypropane; the diacid includes an aromatic diacid or its derivatives and a mixture of aliphatic diacids or their derivatives.

[0027] In this invention, the biodegradable polyester can also be prepared by the following method, exemplarily, the method comprising: (1) Mix aliphatic dicarboxylic acid or its derivative with a diol, a crosslinking agent, and a catalyst of 25-35% of the formulation amount (i.e., the mass of the catalyst added in step (1) accounts for 25-35% of the total mass of the catalyst), and react at 185-195℃ for 2.5-3.5h to obtain product A; (2) Add an aromatic dicarboxylic acid or its derivative and a diol and the remaining catalyst to product A, heat to 242~248℃, and react for 4~6 hours under a pressure of 320~370Pa to obtain the biodegradable polyester.

[0028] In steps (1) and (2), the molar ratio of the diacid to the diol is independently (1.2~1.4):1; the total mass of the catalyst is 0.25~0.32% of the mass of the diacid; the catalyst includes tetrabutyl titanate; the mass of the crosslinking agent is 0.072~0.077% of the mass of the diacid; the crosslinking agent includes trihydroxypropane.

[0029] In this invention, the biodegradable polyester can also be prepared by the following method, exemplarily, the method comprising: 99.2-99.6 parts of commercially available biodegradable polyester were mixed with 0.4-0.8 parts of chain extender and melt-blended in a twin-screw extruder to achieve in-situ chain extension. The extrusion temperatures were 80℃, 120℃, 150℃, 180℃, 180℃, 180℃, 180℃, 180℃, and 190℃, respectively. The speed was 250 rpm, and the extrusion rate was 250 kg / h. The product was then drawn into strands, granulated, and dried at 80℃ for 2 hours to obtain the biodegradable polyester. The chain extender consisted of hexamethylene diisocyanate and BASF ADR 4468 in a mass ratio of 1:1.

[0030] In this invention, unless otherwise specified, the reaction temperature and pressure refer to the reaction being carried out at room temperature and pressure.

[0031] Preferably, the polylactic acid comprises a copolymer of D-lactic acid and L-lactic acid.

[0032] Preferably, the inorganic filler includes any one or a combination of at least two of the following: talc, calcium carbonate, silica, montmorillonite, kaolin, chalk, gypsum, calcium chloride, iron oxide, dolomite, wollastonite, titanium dioxide, silicates, and mica; more preferably, any one or a combination of at least two of the following: talc, calcium carbonate, silica, montmorillonite, and kaolin.

[0033] Preferably, the inorganic filler has a D98 ≤ 15 μm, and can be, for example, 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm or any of the above values; preferably 1~10 μm.

[0034] In this invention, the D98 test method for the inorganic filler is determined in accordance with GB / T 19077.1-2008 "Particle size analysis by laser diffraction".

[0035] Preferably, the biodegradable polyester composite material further includes 0.4 to 8 parts by weight of additives, for example, 0.5 parts, 1 part, 1.5 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts or any range between the above values.

[0036] Preferably, the additives include at least one of lubricant, antioxidant, compatibilizer, nucleating agent, colorant, light stabilizer, and hydrolysis resistant agent.

[0037] In this invention, the weight parts of the lubricant, antioxidant, compatibilizer, nucleating agent, colorant, light stabilizer or hydrolysis resistant agent are each independently 0.1 to 2 parts.

[0038] In this invention, the additives can be selected according to actual needs, as long as they can achieve the corresponding function and do not impair the effect of this invention.

[0039] For example, the lubricant can be used to enhance the slip properties (smoothing properties) during the extrusion process and as an additive to prevent the film surfaces from adhering to each other; the lubricant includes, but is not limited to, at least one of ethylene bis-stearamide (EBS), glyceryl monostearate, oleamide, erucamide, pentaerythritol stearate, polyethylene wax, and silicone lubricants.

[0040] For example, the antioxidant is an additive used to prevent decomposition by ozone or oxygen, to prevent oxidation during storage, and to prevent deterioration of the physical properties of the membrane; the antioxidant includes, but is not limited to, primary antioxidants, such as any one or a combination of at least two of 2,6-di-tert-butyl-p-cresol (BHT), 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6-cyclohexylphenol), 2,2'-methylene-bis(4-methyl-6-nonylphenol), octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, and pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyhydrocinnamate). Co-antioxidants, such as tri(nonylphenyl) phosphite and / or dilauryl thiodipropionate.

[0041] Exemplarily, the compatibilizer is an additive used to impart compatibility by removing the multiphase components of biodegradable polyester, polylactic acid, and starch. The compatibilizer includes, but is not limited to, at least one of polyvinyl acetate (PVAc), isocyanate, polypropylene carbonate, glycidyl methacrylate, ethylene-vinyl alcohol, polyvinyl alcohol (PVA), ethylene-vinyl acetate, or maleic anhydride.

[0042] For example, the nucleating agent is an additive used to supplement or change the crystal morphology of the polymer and to increase the crystallization (solidification) rate when the polymer melt is cooled; the nucleating agent includes, but is not limited to, inorganic compounds (such as calcium carbonate, silicon dioxide, kaolin), low molecular weight organic compounds (such as myristic acid, palmitic acid, stearic acid, behenic acid, monomethyl terephthalate, isophthalic acid), polymers (such as polyethylene glycol, polypropylene glycol, carboxyl-containing polyethylene, acrylic-styrene copolymer), etc.

[0043] For example, the light stabilizer includes at least one of ultraviolet absorbers, ultraviolet shielders, and free radical scavengers; the ultraviolet absorbers include, but are not limited to, benzophenone-based ultraviolet absorbers (such as UV-9, UV-531), benzotriazole-based ultraviolet absorbers (such as UV-326, UV-P, UV-327), and triazine-based ultraviolet absorbers (such as UV-1577, UV-1164). The ultraviolet shielders include, but are not limited to, titanium dioxide, zinc oxide, etc.; the free radical scavengers include, but are not limited to, hindered amine light stabilizers (such as Tinuvin 770, Tinuvin 622, Chimassorb 944), etc.

[0044] In this invention, the hydrolysis-resistant agents include, but are not limited to, isocyanate-based hydrolysis-resistant agents (such as toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, etc.), epoxide-based hydrolysis-resistant agents (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarbamate, epoxidized soybean oil, epoxidized fatty acid methyl ester, etc.), carbodiimide-based hydrolysis-resistant agents (4,4'-dicyclohexylmethane carbodiimide, phenylenediamine carbodiimide, hexamethylene carbodiimide, polycarbodiimide, etc.), polyols (such as ethylene glycol, 1,4-butanediol, etc.), polyamines (such as ethylenediamine, hexamethylenediamine), and polyol amines (such as diethanolamine, etc.).

[0045] In this invention, the colorant includes, but is not limited to, at least one of CI Pigment Yellow 138, CI Pigment Yellow 147, CI Pigment Red 214, CI Pigment Red 242, and carbon black.

[0046] In this invention, the preparation method of the biodegradable polyester composite material is not excessively limited; it can be prepared by conventional methods, including but not limited to the following methods: Polylactic acid, biodegradable polyester, inorganic filler, polycarbonate-type polyurethane, cellulose acetate and optional additives are mixed, melt-extruded and granulated at 150~200℃, cooled and air-dried to obtain the biodegradable polyester composite material.

[0047] In a second aspect, the present invention provides a biodegradable mulch film, wherein the biodegradable mulch film is prepared using the biodegradable polyester composite material described in the first aspect.

[0048] Preferably, the biodegradable mulch film, at a thickness of 10 μm, has a water vapor permeability ≤193 g / (m²). 2 •24h).

[0049] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows: The biodegradable polyester composite material provided by the present invention uses biodegradable polyester with a carboxyl content within a specific range after boiling in water, and polylactic acid, polycarbonate-type polyurethane, cellulose acetate, and inorganic fillers in specific amounts to make the membrane prepared by the biodegradable polyester composite material have a low water vapor permeability. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0052] In this invention, the test method for the carboxyl content of the biodegradable polyester refers to GB / T 14190-2017 (Method A).

[0053] In this invention, the D98 test method for the inorganic filler is determined in accordance with GB / T 19077.1-2008 "Particle size analysis by laser diffraction".

[0054] The specific types of biodegradable polyesters are shown in Table 1.

[0055] Table 1 The specific types of inorganic packing materials are shown in Table 2.

[0056] Table 2 Polylactic acid-1: Anhui Fengyuan Biotechnology Co., Ltd., PLA FY804, melt index is 4.3g / 10min (190℃, 2.16kg).

[0057] Polylactic acid-2: Zhuhai Kingfa Biomaterials Co., Ltd., KB600 NF20, melt index is 4.2g / 10min (190℃, 2.16kg).

[0058] Polycarbonate-type polyurethane: PCU-1: YX-1011 from Jilin Yixian Technology Co., Ltd., with a melt index of 5.6 g / 10min (190℃, 2.16kg).

[0059] PCU-2: YX-2011 from Jilin Yixian Technology Co., Ltd., with a melt index of 18.1 g / 10min (190℃, 2.16kg).

[0060] Polyurethane elastomer: Quadraflex from Biomerics, USA TM ALE-72D has a melt flow index of 5.5 g / 10 min (190℃, 2.16 kg).

[0061] Cellulose acetate CA-1: Eastman Corporation CA-398-3.

[0062] CA-2: Eastman Corporation CA-398-6.

[0063] Corn starch: Purchased from Henan Jindan edible corn starch, with a moisture content of 14wt%.

[0064] Antioxidants, light stabilizers, hydrolysis resistant agents, and lubricants are all sourced from commercially available products.

[0065] Examples 1-19, Comparative Examples 1-11 Examples 1-19 and Comparative Examples 1-11 each provide a biodegradable polyester composite material. The formulations of the biodegradable polyester composite materials are shown in Tables 3-6, by weight. Unless otherwise specified, all values ​​in Tables 3-6 refer to parts by weight. The preparation method of the biodegradable polyester composite material includes: mixing biodegradable polyester, polylactic acid, polycarbonate-type polyurethane, cellulose acetate, and optionally antioxidants, light stabilizers, hydrolysis resistant agents, and lubricants to obtain a premix; then mixing the premix with inorganic fillers in a twin-screw extruder and extruding at 180°C to obtain the biodegradable polyester composite material.

[0066] Table 3 Table 4 Table 5 Table 6 Table 7 Performance testing The biodegradable polyester composite materials provided in the examples and comparative examples were blown into films with a thickness of 10±0.5μm using a blown film machine, and then bagged using a bag-cutting machine. The specific process was as follows: the blown film temperature was 150℃, and the blown film speed was 20kg / h. The resulting biodegradable films were subjected to the following performance tests.

[0067] (1) The test method for water vapor transmission rate includes: in accordance with GB / T 1037-2021 standard, the standard conditions are 38℃±0.6℃ and 90%RH. A permeable cup (filled with distilled water) is used, and the water vapor transmission rate (WVTR) is calculated by the change in the mass of the cup under constant temperature and humidity conditions.

[0068] The specific test results are shown in Table 8.

[0069] Table 8 As shown in Table 8, the biodegradable polyester composite material provided by this invention uses biodegradable polyester with a carboxyl content within a specific range after boiling, blended with polylactic acid, polycarbonate-type polyurethane, cellulose acetate, and inorganic fillers in specific proportions. This results in a membrane with low water vapor transmission rate prepared from the biodegradable polyester composite material. The water vapor transmission rate of the biodegradable polyester composite material is ≤193 g / (m²). 2 •24h).

[0070] As can be seen from Examples 1 and 14-17, the D98 of the inorganic filler within a certain range is beneficial for further reducing water vapor transmission rate.

[0071] As can be seen from Examples 1 and 18-19, using specific types of inorganic fillers is beneficial to further reduce water vapor transmission rate, and the inorganic fillers are more preferably kaolin and calcium carbonate.

[0072] As can be seen from Examples 1 and 6-13, the carboxyl content of the biodegradable polyester after boiling is within a specific range, and the water vapor permeability of the material is low.

[0073] As can be seen from Comparative Examples 1-5, the carboxyl content of the biodegradable polyester after boiling is not within a specific range, and the water vapor permeability of the material is relatively high.

[0074] As can be seen from Comparative Examples 6-9, the content of the polycarbonate-type polyurethane or cellulose acetate is not within a specific range, and the water vapor permeability of the material is relatively high.

[0075] As can be seen from Comparative Examples 10-11, the water vapor permeability of the material is higher when polyurethane elastomer is used to replace polycarbonate-type polyurethane, or when corn starch is used to replace cellulose acetate.

[0076] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biodegradable polyester composite material, characterized in that, By weight, the biodegradable polyester composite material comprises 63-95 parts of biodegradable polyester, 2-10 parts of polylactic acid, 1-10 parts of polycarbonate-type polyurethane, 1-12 parts of inorganic filler and 1-5 parts of cellulose acetate. The carboxyl content of the biodegradable polyester after boiling in water at 95°C for 24 hours is 10~50 mol / t.

2. The biodegradable polyester composite material according to claim 1, characterized in that, The biodegradable polyester has a carboxyl content of 12~40 mol / t after being boiled in water at 95°C for 24 hours, more preferably 14~35 mol / t.

3. The biodegradable polyester composite material according to claim 1, characterized in that, The biodegradable polyester includes aliphatic-aromatic copolyesters; Preferably, the aliphatic-aromatic copolyester comprises any one or a combination of at least two of polybutylene adipate, polybutylene sebacate, and polybutylene succinate.

4. The biodegradable polyester composite material according to claim 1, characterized in that, The polylactic acid includes copolymers of D-lactic acid and L-lactic acid.

5. The biodegradable polyester composite material according to claim 1, characterized in that, The inorganic filler includes any one or a combination of at least two of the following: talc, calcium carbonate, silica, montmorillonite, kaolin, chalk, gypsum, calcium chloride, iron oxide, dolomite, wollastonite, titanium dioxide, silicates, and mica; preferably, any one or a combination of at least two of the following: talc, calcium carbonate, silica, montmorillonite, and kaolin.

6. The biodegradable polyester composite material according to claim 1, characterized in that, The inorganic filler has a D98 ≤ 15 μm, preferably 1~10 μm.

7. The biodegradable polyester composite material according to claim 1, characterized in that, The biodegradable polyester composite material further includes 0.4 to 8 parts by weight of additives.

8. The biodegradable polyester composite material according to claim 7, characterized in that, The additives include at least one of the following: lubricant, antioxidant, compatibilizer, nucleating agent, colorant, light stabilizer, and hydrolysis resistant agent.

9. A biodegradable mulch film, characterized in that, The biodegradable mulch film is prepared using the biodegradable polyester composite material described in any one of claims 1 to 8.

10. The biodegradable mulch film according to claim 9, characterized in that, The biodegradable mulch film, at a thickness of 10 μm, has a water vapor permeability ≤193 g / (m²). 2 •24h).

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