A polyester composition and use thereof

Abstract

The application provides a polyester composition and application thereof. The polyester composition comprises 60-93 parts by weight of polyester, 1-8 parts by weight of polylactic acid and 6-32 parts by weight of starch; the storage modulus of the polyester at 100 Hz is 30000-320000 Pa. In the application, the polyester composition is prepared by compounding polyester with specific storage modulus, polylactic acid and starch, so that the composite material formed by the polyester, the polylactic acid and the starch has excellent low odor effect.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable polymer materials technology, specifically relating to a polyester composition and its application. Background Technology

[0002] To address the problem of white pollution, biodegradable materials are gradually being used to replace non-degradable traditional plastics such as polyethylene (PE) and polypropylene (PP).

[0003] Currently, commonly used biodegradable plastics include polyesters (such as polybutylene terephthalate), polylactic acid (PLA), and starch. To obtain biodegradable materials with superior performance, blends of polyester, PLA, and starch are often used. However, when these composite materials are applied to film bags, consumers generally report a stronger odor than traditional PE bags. This hinders the widespread use of biodegradable materials, particularly in food packaging, such as takeout bags and beverage bags, severely limiting their expansion.

[0004] To reduce the odor of materials, the existing method is to add deodorizing agents, but the addition of deodorizing agents significantly increases the cost.

[0005] Therefore, developing a low-odor starch-based polyester composite material is an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a polyester composition and its applications. This polyester composition solves the problem of high odor in starch-based polyester composite materials in the prior art.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polyester composition comprising, by weight, 60-93 parts polyester, 1-8 parts polylactic acid and 6-32 parts starch; wherein the polyester has a storage modulus of 30,000-320,000 Pa at 100 Hz.

[0008] In this invention, the use of polyester with a specific energy storage modulus is beneficial for better plasticization of starch, inhibits the shearing damage to starch during twin-screw processing, improves plasticization efficiency, and makes the polyester composition have a low odor. The addition of polylactic acid is beneficial for further reducing the odor of the polyester composition. The use of the polyester, polylactic acid and starch compound makes the final material have low odor.

[0009] In this invention, 60 to 93 parts of polyester can be, for example, 60 parts, 62 parts, 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 or any range between the above values, and more preferably 69 to 83 parts.

[0010] In this invention, the polyester composition contains ≥50% by mass, preferably 58-85%, and more preferably 65-75%.

[0011] In this invention, 1 to 8 parts of polylactic acid, for example, can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts or any range between the above values, preferably 3.5 to 6.5 parts.

[0012] In this invention, the polylactic acid content in the polyester composition is ≤10% by mass, preferably 1~8%, and more preferably 3~5%.

[0013] In this invention, 6 to 32 parts of starch, for example, can be 6 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, 31 parts or any range between the above values, preferably 14 to 24 parts.

[0014] In this invention, the starch content in the polyester composition is ≤35% by mass, preferably 5~30%, and more preferably 10~25%.

[0015] In this invention, the storage modulus of the polyester at 100Hz is 30,000~320,000 Pa, for example, it can be 30,000 Pa, 50,000 Pa, 70,000 Pa, 90,000 Pa, 110,000 Pa, 130,000 Pa, 150,000 Pa, 170,000 Pa, 190,000 Pa, 210,000 Pa, 230,000 Pa, 250,000 Pa, 270,000 Pa, 290,000 Pa, 310,000 Pa or any range of the above values, further preferably the storage modulus is 60,000~270,000 Pa, and particularly preferably the storage modulus is 90,000~230,000 Pa.

[0016] In this invention, the energy storage modulus is obtained by rotational rheometer testing, and the sample thickness is 3 mm. Within a specific range, the energy storage modulus can both improve the plasticization efficiency of starch and avoid the breakage of starch molecular chains, thereby reducing the probability of the formation of small molecules that can be perceived by the sense of smell, thus ensuring the low odor effect of the material.

[0017] Preferably, the polyester comprises an aliphatic-aromatic polyester.

[0018] In this invention, the polyester 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%, more preferably 41-49%.

[0019] 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.

[0020] Preferably, the polyester comprises at least one of polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT), or polybutylene terephthalate succinate (PBST).

[0021] In this invention, the moisture content of the polyester is 200~1000ppm, more preferably 500~800ppm.

[0022] In this invention, the polyester can be obtained by commercial purchase or by conventional methods. For example, the preparation method includes: mixing a diacid with a diol and an optional crosslinking agent to carry out an esterification reaction to obtain an esterified product; and carrying out a polycondensation reaction on the esterified product to obtain the polyester.

[0023] Those skilled in the art can obtain polyesters with the desired storage modulus by adjusting the composition of the diacid, the amount of crosslinking agent, the esterification reaction time, and the polycondensation reaction time. For example, when the raw material composition remains unchanged (i.e., the content of different types of diacids, diols, and crosslinking agents remains unchanged), a high-modulus polyester can be obtained by extending the esterification reaction time and / or extending the polycondensation reaction time. Alternatively, without extending the esterification reaction time and / or the polycondensation reaction time, a high-modulus polyester can be obtained by adjusting the composition of the diacid and / or increasing the content of the crosslinking agent. Specifically, adjusting the composition of the diacid involves increasing the proportion of aromatic diacids to obtain a high-modulus polyester. The above variables can also be adjusted simultaneously to obtain a polyester with the desired modulus.

[0024] For example, when the diacid is selected from terephthalic acid and adipic acid, and the diol is selected from butanediol, in one specific embodiment of the present invention, the preparation method of the polyester includes the following steps: reacting a diacid and a diol in a molar ratio of 1:(1.4~1.6) and a crosslinking agent (including glycerol, with a mass of 0.055~0.065% of the diacid mass) at 185~195°C for 2.5~4.5h to obtain an esterification product; then mixing the esterification product with a catalyst (such as tetrabutyl titanate, with a molar content of 0.01~0.03% of the total molar amount of the diacid and the diol) and reacting at 235~245°C and 250~350Pa for 4.5~6.5h to obtain polybutylene adipate terephthalate, which is the polyester.

[0025] In this invention, the polyester can also be prepared by an independent esterification-polymerization process. The independent esterification refers to reacting an aliphatic diacid and / or its derivatives, and an aromatic diacid and / or its derivatives, with a diol to obtain two esterification products. Then, the two esterification products are subjected to a polymerization reaction to obtain the polyester.

[0026] Those skilled in the art can also obtain polyesters with the desired storage modulus by adjusting the composition of the diacid, the amount of crosslinking agent, the esterification reaction time, the polycondensation reaction time, etc.; for example, when the diacid is selected from terephthalic acid and adipic acid, and the diol is selected from butanediol, in a specific embodiment of the present invention, the method for preparing the polyester includes the following steps: (1) Terephthalic acid and butanediol are mixed in a molar ratio of 1:(1.4~1.6) and pre-esterified at 215~225℃. During the esterification process, water is continuously removed until no esterified water is discharged, and the first esterified product is obtained. Adipic acid and butanediol are mixed in a molar ratio of 1:(1.4~1.6) and crosslinking agent (including glycerol, with a mass of 0.055~0.065% of the total mass of dicarboxylic acid) and pre-esterified at 175~185℃. During the esterification process, water is continuously removed until no esterified water is discharged, and the second esterified product is obtained. (2) The first esterification product and the second esterification product and the catalyst (such as tetrabutyl titanate, with a molar content of 0.01~0.03% of the total molar amount of dicarboxylic acid and diol) are mixed and polycondensed at 235~245℃ and 250~350Pa for 4.5~5.5h to obtain the polyester.

[0027] Preferably, the polylactic acid includes a copolymer of D-lactic acid and L-lactic acid (PLLA / PDLA copolymer).

[0028] In this invention, the D-type molar content of the polylactic acid is 0.1-15% or the D-type molar content of the polylactic acid is 85-99%.

[0029] In this invention, the moisture content of the polylactic acid is ≤0.05wt%.

[0030] Preferably, the starch comprises plant starch and / or plant starch derivatives.

[0031] Preferably, the plant starch includes at least one of corn starch, potato starch, rice starch, tapioca starch, or pea starch.

[0032] Preferably, the plant starch derivative includes at least one of esterified derivatives, etherified derivatives, or oxidized derivatives.

[0033] In this invention, the moisture content of the starch is 8-20 wt%, more preferably 10-15 wt%.

[0034] Preferably, the polyester composition further includes a plasticizer.

[0035] Preferably, the plasticizer is 5-40% of the starch mass, for example, it can be 5%, 7%, 9%, 11%, 13%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29%, 31%, 33%, 35%, 37%, 39% or any of the above values, more preferably 8-35%, and particularly preferably 15-32%.

[0036] Preferably, the plasticizer comprises a small molecule organic compound and / or water; the small molecule organic compound contains hydroxyl and / or ester groups in its molecular structure.

[0037] Preferably, the small molecule organic compound includes at least one of glycerol, diglycerol, triglycerol, tetraglycerol, epoxidized soybean oil, citrate, acetylsicitrate, sorbitol, ethylene glycol, or polyethylene glycol, more preferably at least one of glycerol, diglycerol, triglycerol, epoxidized soybean oil, ethylene glycol, or sorbitol.

[0038] Preferably, the plasticizer comprises a small molecule organic compound and water, wherein the mass ratio of the small molecule organic compound to water is (0.2~4):1, wherein the specific value of (0.2~4) can be, for example, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4 or any range between the above values, preferably (0.5~2.5):1, and more preferably (0.6~1.2):1.

[0039] In this invention, a specific amount of small molecule organic compound and water are used in combination to enhance the intermolecular forces and reduce the odor of the polyester composition.

[0040] Preferably, the polyester composition further comprises 0.1 to 2 parts by weight of an auxiliary agent, for example, 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.5, 1.8, 2 parts or any range of the above values.

[0041] Preferably, the additives include at least one of the following: opening agent, lubricant, antioxidant, compatibilizer, nucleating agent, colorant, or stabilizer.

[0042] 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.

[0043] For example, the opening agent includes, but is not limited to, one or more of talc, montmorillonite, zeolite or barium sulfate, preferably talc and / or montmorillonite; the mass percentage of the opening agent in the polyester composition can be 0.1-2%.

[0044] 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 erucamide, oleamide, glyceryl monostearate, pentaerythritol stearate, PE wax, ethylene bis-stearamide (EBS) or silicone lubricants; the mass percentage of the lubricant in the polyester composition can be 0.1-2%.

[0045] 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). The composition may contain auxiliary antioxidants, such as tri(nonylphenyl) phosphite and / or dilauryl thiodipropionate; the antioxidant content in the polyester composition may be 0.1-2% by mass.

[0046] Exemplarily, the compatibilizer is an additive used to impart compatibility through the multiphase composition of 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; the mass percentage of the compatibilizer in the polyester composition can be 0.1% to 2%.

[0047] For example, the nucleating agent is an additive used to supplement or change the crystalline 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, silica, kaolin, talc, barium sulfate), 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.; the mass percentage of the compatibilizer in the polyester composition can be 0.1-2%.

[0048] For example, the stabilizer is an additive used to protect against oxidation and heat and to prevent color changes. The stabilizer includes, but is not limited to, at least one of trimethyl phosphate, triphenyl phosphate, trimethylphosphine, phosphoric acid, and phosphorous acid; the mass percentage of the stabilizer in the polyester composition can be 0.1% to 2%.

[0049] In this invention, the preparation method of the polyester composition is not excessively limited; it can be prepared by conventional methods, including but not limited to the following methods: Polylactic acid, polyester, starch, plasticizer and optional additives are mixed, melt-extruded and granulated at 150~200°C, cooled and air-dried to obtain the polyester composition.

[0050] In a second aspect, the present invention provides a biodegradable film or bag, wherein the biodegradable film or bag is prepared using the polyester composition described in the first aspect.

[0051] Preferably, the odor level of the biodegradable film or bag after heating at 80±2℃ for 2 h and cooling to 60±5℃ is ≤4.4, and more preferably 3~4.

[0052] 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.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows: The polyester composition provided by the present invention uses polyester with a specific energy storage modulus to be compounded with polylactic acid and starch in a specific amount, so that the composite material formed by polyester, polylactic acid and starch achieves a low odor effect. Detailed Implementation

[0054] 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.

[0055] In this invention, the storage modulus of the polyester at 100Hz was obtained by testing with a rotational rheometer (Discovery's HR-2 rheometer). The specific steps include: placing an appropriate amount of polyester particles into a 100×100×3mm frame mold, isolating the top and bottom with PET film, rapidly heating to 160℃ using a flat vulcanizing apparatus, pressing for 3 minutes, releasing the gas once, pressing for 0.5 minutes, releasing the gas once more, pressing for 2 minutes, and finally cooling on a cooling plate at 30±5℃ for 5 minutes. Finally, peeling off the PET film yields a 100×100×3mm sheet.

[0056] The obtained sheet was cut into small samples of 10×10×3mm and placed in a rotational rheometer, where it was equilibrated at 150℃ for 5 minutes. Then, a strain scan experiment was performed with a strain of 1.0% and a shear rate from 0.01Hz to 100Hz. The loss modulus at 100Hz was read, which is the storage modulus of the polyester at 100Hz, and is denoted as G′.

[0057] In this invention, the method for testing moisture content includes: drying the sample at 60°C until its weight does not change, and obtaining the moisture content of the sample by measuring the mass change before and after drying.

[0058] All materials used in this invention can be purchased commercially or prepared using conventional methods. Unless otherwise specified, the materials used in this invention are as follows.

[0059] The polyester used in this invention is obtained in-house, and its types and G′ are shown in Table 1; the specific in-house preparation method is as follows.

[0060] PBAT-1: 1.910 kg of terephthalic acid, 1.978 kg of adipic acid, and 2.6 kg of excess 1,4-butanediol were added to a 20 L reactor. Then, 2.3 g of glycerol was added, and the mixture was stirred at 190 °C for 3 h (referred to as the first stage). Tetrabutyl titanate (molar content of 0.02% of the total molar amount of diacid and diol) was then added. The temperature was raised to 240 °C, and a vacuum was applied at a pressure of 300 Pa. The mixture was reacted for 5 h (referred to as the second stage). The mixture was then granulated and dried to obtain PBAT-1 with a moisture content of 768 ppm.

[0061] PBAT-2: The difference from PBAT-1 is that the mass of glycerol is 2.1g, the reaction time for the first stage is 2h, and the reaction time for the second stage is 3.5h. Other parameters are the same as PBAT-1. The resulting PBAT-2 has a moisture content of 684 ppm.

[0062] PBAT-3: The difference from PBAT-1 is that the mass of glycerol is 2.45g, the reaction time of the first stage is 4.5h, and the reaction time of the second stage is 6.5h. Other parameters are the same as PBAT-1. The resulting PBAT-2 has a moisture content of 796 ppm.

[0063] PBAT-4 differs from PBAT-1 in that it uses 1.861 kg of terephthalic acid, 2.017 kg of adipic acid, and 2.08 g of glycerol. The first-stage reaction time is 2.2 h, and the second-stage reaction time is 4.6 h. Other parameters are the same as PBAT-1. The resulting PBAT-2 has a moisture content of 596 ppm.

[0064] PBAT-5: The difference from PBAT-1 is that the mass of glycerol is 2.25g, the reaction time for the first stage is 5.5h, and the reaction time for the second stage is 8h. Other parameters are the same as PBAT-1. The resulting PBAT-2 has a moisture content of 705 ppm.

[0065] PBAT-6: Its preparation method involves an independent esterification process to first prepare two esterified products, then mixing the two esterified products and carrying out a polycondensation reaction to obtain PBAT-6. The specific steps are as follows: At 220°C, 1.910 kg of terephthalic acid and 1.3 kg of excess 1,4-butanediol are pre-esterified in a 5L reactor. During the esterification process, water is continuously removed until no esterified water is discharged, thus completing the esterification process and obtaining the first esterified product. At 180°C, 1.978 kg of adipic acid and excess 1,4-butanediol are... 1.1 kg was added to a 5 L reactor for pre-esterification, and an additional 2.3 g of glycerol was added. During the esterification process, water was continuously removed until no esterified water was discharged, thus completing the esterification process and obtaining the second esterified product. The first and second esterified products were then added together to a 20 L reactor, and tetrabutyl titanate (molar content of 0.02% of the total molar amount of dicarboxylic acid and diol) was added. The temperature was raised to 240 °C, the vacuum was turned on, the vacuum pressure was 300 Pa, and the reaction was carried out for 5 h (referred to as the second stage). The product was then granulated and dried to obtain PBAT-6 with a moisture content of 619 ppm.

[0066] PBSeT: 1.910 kg of terephthalic acid, 2.735 kg of sebacic acid, and 2.6 kg of excess 1,4-butanediol were added to a 20 L reactor. 2.3 g of glycerol was added, and the mixture was stirred at 190 °C for 3 h. Then, tetrabutyl titanate (molar content of 0.02% of the total molar amount of the diacid and diol) was added. The temperature was raised to 240 °C, a vacuum was applied at 300 Pa, and the reaction was carried out for 5 h. The mixture was then granulated and dried to obtain PBSeT. The moisture content of the obtained PBSeT was 711 ppm.

[0067] PBAT-d1: The difference between PBAT-d1 and PBAT-1 is that the amount of terephthalic acid is 1.861 kg, adipic acid is 2.017 kg, and the mass of glycerol is 1.23 g. The reaction time for the first stage is 1.3 h, and the reaction time for the second stage is 3.5 h. Other parameters are the same as PBAT-1. The resulting PBAT-d1 has a moisture content of 921 ppm.

[0068] PBAT-d2: The difference from PBAT-1 is that the mass of terephthalic acid is 2.156 kg, adipic acid is 1.758 kg, and glycerol is 2.3 g. The reaction time for the first stage is 5 h, and the reaction time for the second stage is 8 h. Other parameters are the same as PBAT-1. The resulting PBAT-d1 has a moisture content of 931 ppm. PBAT-d3: The difference from PBAT-1 is that the reaction time for the first stage is 6 h, and the reaction time for the second stage is 12 h. After pelleting and drying, PBAT-d3 is obtained. The resulting PBAT-d1 has a moisture content of 863 ppm.

[0069] Table 1 Polylactic acid: PLA FY804, Anhui Fengyuan Biotechnology Co., Ltd., moisture content is 0.04wt%.

[0070] Starch 1: Henan Jindan, edible corn starch, moisture content 14.1 wt%. Starch 2: Potato starch, Beidahuang Group, moisture content 13.2 wt%.

[0071] Plasticizers, opening agents, and lubricants are sourced from commercially available products.

[0072] Examples 1-22 and Comparative Examples 1-3 each provide a polyester composition. The formulations of the polyester compositions, by weight, are shown in Tables 2-5; where " / " indicates that the component is not in the formulation. Unless otherwise specified, all values ​​in Tables 2-5 refer to parts by weight, and the content of the plasticizer indicates its percentage content relative to the mass of starch. The preparation method of the polyester composition includes: mixing polyester, polylactic acid, starch, plasticizer, and optionally an opening agent and lubricant, and extruding at 180°C to obtain the polyester composition.

[0073] Table 2 Table 3 Table 4 Table 5 Performance testing The polyester compositions provided in the examples and comparative examples were blown into films with a thickness of 12±1 μm 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°C, and the blown film speed was 20 kg / h. The resulting biodegradable films were subjected to the following performance tests.

[0074] (1) Odor rating: Referencing the Volkswagen PV 3900-2000 standard test, cut 50 g of biodegradable film and place it in a 1 L odor bottle, seal it with aluminum foil, heat it in an oven at (80±2)℃ for 2 h, remove it and cool it to (60±5)℃, open the odor bottle cap, and have at least 3 people quickly complete the odor test rating. The rating is based on Table 6. Different intermediate levels (such as 5.5, 4.5, 3.5, 2.5, 1.5) can be rated according to the specific situation. The result is the average of multiple people.

[0075] Table 6 The specific test results are shown in Table 7.

[0076] Table 7 As shown in Table 7, the polyester composition provided by the present invention uses polyester with a specific energy storage modulus to be compounded with polylactic acid and starch in a specific amount, so that the composite material formed by polyester, polylactic acid and starch achieves a low odor effect; the odor level of the polyester composition is ≤4.4.

[0077] As can be seen from Examples 1, 6-9, 21, and Comparative Examples 1-3, the storage modulus of the polyester at 100Hz is not in the range of 30000~320000Pa, and the material odor deteriorates.

[0078] As can be seen from Examples 1, 10-13, using a specific amount of plasticizer (i.e., 5-40% of the starch mass) is beneficial to further reduce odor.

[0079] As can be seen from Examples 1, 14-20, and 22, using specific types or combinations of plasticizers is beneficial for further reducing odor.

[0080] 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 polyester composition, characterized in that, The polyester composition comprises, by weight, 60-93 parts polyester, 1-8 parts polylactic acid and 6-32 parts starch; The storage modulus of the polyester at 100 Hz is 30,000~320,000 Pa.

2. The polyester composition according to claim 1, characterized in that, The polyester has a storage modulus of 60,000 to 270,000 Pa at 100 Hz, preferably 90,000 to 230,000 Pa.

3. The polyester composition according to claim 1 or 2, characterized in that, The polyester includes aliphatic-aromatic polyesters; Preferably, the polyester comprises at least one of polybutylene adipate terephthalate, polybutylene sebacate terephthalate, or polybutylene succinate terephthalate.

4. The polyester composition according to any one of claims 1 to 3, characterized in that, The polylactic acid includes a copolymer of D-lactic acid and L-lactic acid.

5. The polyester composition according to any one of claims 1 to 4, characterized in that, The starch includes plant starch and / or plant starch derivatives; Preferably, the plant starch includes at least one of corn starch, potato starch, rice starch, tapioca starch, or pea starch; Preferably, the plant starch derivative includes at least one of esterified derivatives, etherified derivatives, or oxidized derivatives.

6. The polyester composition according to any one of claims 1 to 5, characterized in that, The polyester composition further includes a plasticizer; Preferably, the plasticizer is 5-40% of the starch mass, more preferably 8-35%, and particularly preferably 15-32%.

7. The polyester composition according to claim 6, characterized in that, The plasticizer comprises a small molecule organic compound and / or water; the small molecule organic compound contains hydroxyl and / or ester groups in its molecular structure; Preferably, the small molecule organic compound includes at least one of glycerol, diglycerol, triglycerol, tetraglycerol, epoxidized soybean oil, citrate, acetylsicitrate, sorbitol, ethylene glycol, or polyethylene glycol, more preferably at least one of glycerol, diglycerol, triglycerol, epoxidized soybean oil, ethylene glycol, or sorbitol.

8. The polyester composition according to claim 6 or 7, characterized in that, The plasticizer comprises a small molecule organic compound and water, wherein the mass ratio of the small molecule organic compound to water is (0.2~4):1, preferably (0.5~2.5):1, and more preferably (0.6~1.2):1; Preferably, the polyester composition further includes 0.1 to 2 parts by weight of an auxiliary agent; Preferably, the additives include at least one of the following: opening agent, lubricant, antioxidant, compatibilizer, nucleating agent, colorant, or stabilizer.

9. A biodegradable film or bag, characterized in that, The biodegradable film or bag is prepared using the polyester composition according to any one of claims 1 to 8.

10. The biodegradable film or bag according to claim 9, characterized in that, The biodegradable film or bag, after being heated at 80±2℃ for 2 hours and cooled to 60±5℃, has an odor level ≤4.4, preferably 3~4.

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