Biodegradable polyester composition and application thereof

Abstract

The invention provides a biodegradable polyester composition and application thereof, the biodegradable polyester composition comprises, by weight, 40-93 parts of polyester, 2-20 parts of polylactic acid, 5-40 parts of a filler and 0.5-5 parts of a nucleating agent; the ratio of the low-frequency composite viscosity number to the high-frequency composite viscosity number of the polyester is 2-100. The biodegradable polyester composition has high film blowing yield in the film blowing forming process.

Description

Technical Field

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

[0002] With the increasing severity of white pollution, the search for more environmentally friendly materials to replace traditional non-degradable materials has become urgent. Biodegradable materials, because they can be decomposed by microorganisms in the natural environment, can significantly reduce the pollution caused by materials. They are also low in cost and have good overall performance, and are widely used in everyday products such as packaging films, agricultural films, disposable bags, and disposable tableware.

[0003] To obtain biodegradable materials with better performance, polyester, polylactic acid and fillers are usually used to make a compound, thereby expanding the application range of biodegradable materials; however, for this system composition, the blown film production process has a low blown film yield, which seriously affects the production efficiency.

[0004] Therefore, developing a biodegradable polyester composition with high blown film yield 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 composition and its applications. The biodegradable polyester composition exhibits high blown film yield during the blown film forming process.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a biodegradable polyester composition, wherein, by weight, the biodegradable polyester composition comprises 40-93 parts polyester, 2-20 parts polylactic acid, 5-40 parts filler and 0.5-5 parts nucleating agent; the ratio of the low-frequency composite viscosity to the high-frequency composite viscosity of the polyester is 2-100.

[0007] In this invention, the low-frequency composite viscosity (V) L The composite viscosity (V) refers to the composite viscosity at 0.01 Hz. High-frequency composite viscosity (V) H The composite viscosity at 100 Hz is used; the test temperature is 150 ℃; the specific test method includes: pressing the polyester into a 3 mm sheet using a sheet forming machine, placing it in a rotational rheometer, equilibrating it at 150 ℃ for 5 min, and then performing a strain scan experiment with a strain of 1.0% and a shear rate from 0.01 Hz to 100 Hz. The composite viscosity at 0.01 Hz and 100 Hz is read, which are the low-frequency composite viscosity and high-frequency composite viscosity.

[0008] In this invention, by controlling the ratio of the low-frequency composite viscosity to the high-frequency composite viscosity of the polyester within a specific range, it is beneficial to rapidly cool and solidify the film bubble during the blown film forming process, thereby increasing the blown film output.

[0009] In this invention, 40 to 93 parts of polyester can be, for example, 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 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 of the above values; more preferably, 49 to 77 parts, and particularly preferably 57 to 73 parts.

[0010] In this invention, the biodegradable polyester composition contains ≥40% by mass of polyester, more preferably 45-80%, and particularly preferably 55-65%.

[0011] In this invention, 2 to 20 parts of polylactic acid can be, for example, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, or any combination thereof. A polylactic acid content within a specific range is more conducive to increasing blown film production. If the polylactic acid content is too high, the compatibility between polylactic acid and polyester gradually decreases, leading to phase separation at the microscopic interface and affecting blown film production. If the content is too low, the material stiffness is low, which is not conducive to blown film production, resulting in low blown film production. Preferably, it is 5 to 17 parts, and particularly preferably 8 to 13 parts.

[0012] In this invention, the mass percentage of polylactic acid in the biodegradable polyester composition is ≥2%, more preferably 5~16%, and particularly preferably 7~13%.

[0013] In this invention, the biodegradable polyester composition further includes 5 to 40 parts of filler, for example, a range of 5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40 parts or any combination thereof, more preferably 12 to 35 parts, and particularly preferably 19 to 27 parts.

[0014] In this invention, 0.5 to 5 parts of nucleating agent can be, for example, 0.5 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, or any combination thereof; preferably 1 to 4 parts, more preferably 1.8 to 3.5 parts.

[0015] In this invention, the mass percentage of nucleating agent in the biodegradable polyester composition is ≥0.5%, more preferably 1.2~3.9%, and particularly preferably 1.7~3.4%.

[0016] In this invention, the ratio of the low-frequency composite viscosity number to the high-frequency composite viscosity number of the polyester is 2 to 100, for example, it can be a range of 2, 4, 6, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50, 52, 55, 58, 60, 62, 65, 68, 70, 72, 75, 78, 80, 82, 85, 88, 90, 92, 95, 98, 100 or any two of these values; the ratio of the low-frequency composite viscosity number to the high-frequency composite viscosity number of the polyester is 4 to 80, preferably 6 to 50.

[0017] Preferably, the low-frequency composite viscosity of the polyester is 1000~5000 Pa•s, for example, it can be a range of 1000 Pa•s, 1200 Pa•s, 1400 Pa•s, 1600 Pa•s, 1800 Pa•s, 2000 Pa•s, 2200 Pa•s, 2400 Pa•s, 2600 Pa•s, 2800 Pa•s, 3000 Pa•s, 3200 Pa•s, 3400 Pa•s, 3600 Pa•s, 3800 Pa•s, 4000 Pa•s, 4200 Pa•s, 4400 Pa•s, 4600 Pa•s, 4800 Pa•s, 5000 Pa•s or any two of these values; more preferably, it is 1400~4200 Pa•s, and more preferably, it is 1800~2800 Pa•s.

[0018] Preferably, the polyester comprises an aliphatic-aromatic copolyester and / or an aliphatic polyester, more preferably an aliphatic-aromatic copolyester.

[0019] In this invention, the polyester is a flexible, biodegradable polyester.

[0020] In this invention, the aliphatic-aromatic copolyester comprises the following components: Component A: A dicarboxylic acid component containing the following components: a1) Based on a total molar percentage of 100 mol% of a1) and a2), 30-70 mol% of aromatic dicarboxylic acids and / or their derivatives; more preferably 40-60 mol%; a2) Based on the total molar percentage of a1) and a2) 100 mol%, 30-70 mol% of aliphatic dicarboxylic acids and / or their derivatives; more preferably 40-60 mol%; Component B: An aliphatic diol in at least an equimolar amount with component A.

[0021] In this invention, the aliphatic-aromatic copolyester further includes the following components: Component C: based on the total mass percentage of a1) and a2) of 100 wt%, 0.01 to 0.5% of a crosslinking agent, more preferably 0.024 to 0.46%.

[0022] In this invention, the aromatic dicarboxylic acid and / or its derivatives include, but are not limited to, at least one of terephthalic acid and / or its derivatives, isophthalic acid and / or its derivatives, phthalic acid and / or its derivatives, furanyl dicarboxylic acid and / or its derivatives, more preferably terephthalic acid and / or its derivatives; the aliphatic dicarboxylic acid and / or its derivatives include, but are not limited to, at least one of oxalic acid and / or its derivatives, malonic acid and / or its derivatives, succinic acid and / or its derivatives, adipic acid and / or its derivatives, pimelic acid and / or its derivatives, octanoic acid and / or its derivatives, sebacic acid and / or its derivatives, dodecyl diacid and / or its derivatives, more preferably at least one of succinic acid and / or its derivatives, adipic acid and / or its derivatives, sebacic acid and / or its derivatives.

[0023] In this invention, the derivatives of the aromatic diacids include diC1-C6 alkyl esters of aromatic diacids; the derivatives of the aliphatic diacids include diC1-C6 alkyl esters of aliphatic diacids; each of the C1-C6 alkyl esters independently includes, but is not limited to, dimethyl ester, diethyl ester, di-n-propyl ester, diisopropyl ester, di-n-butyl ester, diisobutyl ester, di-tert-butyl ester, di-n-pentyl ester, diisopentyl ester, or di-n-hexyl ester.

[0024] In this invention, the aliphatic diol includes, but is not limited to, at least one of ethylene glycol, propylene glycol, butanediol, hexanediol, and decanediol; more preferably, butanediol.

[0025] In this invention, the crosslinking agent has a functionality of ≥3, for example, it can be 3, 4, 5, 6, etc.

[0026] In this invention, the crosslinking agent contains at least one of hydroxyl, carboxyl, or anhydride groups in its molecular structure; the functionality ≥3 refers to the total functionality of hydroxyl, carboxyl, and anhydride groups in the molecular structure being ≥3; and compounds having 3 to 6 hydroxyl groups are particularly preferred.

[0027] Preferably, the crosslinking agent comprises at least one of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, trihydroxypropane, 1,3,5-benzotriic acid, 1,2,4-benzotriic acid, 1,2,4-benzotriic anhydride, 1,2,4,5-benzotetrate or benzopyrenic acid dianhydride, and more preferably at least one of trimethylolpropane, pentaerythritol or trihydroxypropane.

[0028] 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).

[0029] In this invention, the aliphatic polyester comprises an aliphatic diacid and / or its derivative component and an aliphatic diol component in at least an equimolar amount of the aliphatic diacid and / or its derivative component; the aliphatic diacid and / or its derivative component is selected from the same range as the aliphatic diacid and / or its derivative component in aliphatic-aromatic copolyesters; the aliphatic diol is selected from the same range as the aliphatic diol component in aliphatic-aromatic copolyesters.

[0030] Preferably, the aliphatic polyester comprises polybutylene succinate (PBS).

[0031] In this invention, the polyester can be obtained commercially or prepared using conventional methods. Exemplarily, the preparation method includes: reacting a diacid with a diol in a one-step process; specifically: mixing the diacid, diol, and optionally a crosslinking agent and catalyst at 188-194°C and atmospheric pressure for 0.18-1.02 h, then heating to 242-248°C and reacting at a pressure of 480-520 Pa for 3.2-14.2 h, then adding a chain extender and continuing the reaction for 0.8-1.2 h to obtain the polyester; the molar ratio of the diacid to the diol is 1:(1.1-1.15); the mass of the catalyst is 0.4-0.5% of the total mass of the diacid and diol; the catalyst includes tetrabutyl titanate; the mass of the chain extender is 0.022-0.028% of the total mass of the diacid, and the chain extender includes diphenylmethane diisocyanate.

[0032] In this invention, the polyester can also be prepared by chain extension reaction of commercially available polyester; exemplaryly, the preparation method includes: reacting commercially available polyester with a chain extender at a temperature of 185~195℃ for 3~8 min, and then drying at 70~90℃ for 4~6 h to obtain the polyester; the mass of the chain extender is 0.3~0.7% of the polyester; the chain extender includes at least one of isocyanate compounds, isocyanurate compounds, peroxides, epoxides, oxazoline compounds, oxazine compounds, caprolactam or carbodiimide, and more preferably epoxides (such as BASF's ADR 4468) and / or isocyanate compounds (such as hexamethylene diisocyanate, isophorone diisocyanate, etc.); the chain extension reaction can be carried out in a twin-screw extruder.

[0033] In this invention, the polyester can also be obtained by melt extrusion of at least two different commercially available polyesters at 185-195°C, granulation, and then drying the resulting granules at 70-90°C for 4-6 hours; for example, it can be prepared by melt extrusion of polyester KB100 HF and KB100 LF from Zhuhai Kingfa Biotechnology in a mass ratio of 1.5:1.

[0034] Preferably, the polylactic acid includes at least one of poly-D-lactic acid (PDLA), poly-L-lactic acid (PLLA), or a copolymer of D-lactic acid and L-lactic acid (PDLA-PLLA copolymer), more preferably a copolymer of D-lactic acid and L-lactic acid.

[0035] In this invention, the melt index of the polylactic acid is 2~50g / 10min at 190℃ and 2.16kg.

[0036] In this invention, the melt index of the polylactic acid can be measured by the ISO 1133-1:2022 standard.

[0037] Preferably, the polylactic acid is selected from D-lactic acid and L-lactic acid copolymers, wherein the D-lactic acid and L-lactic acid copolymers include a first D-lactic acid and L-lactic acid copolymer and / or a second D-lactic acid and L-lactic acid copolymer, more preferably a first D-lactic acid and L-lactic acid copolymer.

[0038] Preferably, the molar content of D-lactic acid in the first D-lactic acid and L-lactic acid copolymer is 0.1-5%, for example, it can be a range of 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, or any combination thereof; more preferably, it is 0.5-4%, and particularly preferably 1.5-3%.

[0039] Preferably, the molar content of D-lactic acid in the second D-lactic acid and L-lactic acid copolymer is 85-99%, for example, it can be a range of 85%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 99% or any two of these; more preferably, it is 93-98%.

[0040] In this invention, the molar content of D-lactic acid in polylactic acid is determined by analyzing and testing the polylactic acid after it has undergone sufficient transesterification degradation using a gas chromatograph. The characteristic peak areas of D-lactic acid ester and L-lactic acid ester are integrated, and the molar content of D-lactic acid in polylactic acid is obtained by the percentage of the integrated area.

[0041] In this invention, the polylactic acid can be obtained commercially or prepared using conventional methods. Exemplarily, the preparation method includes: mixing a monomer with a catalyst and reacting to obtain the polylactic acid; the monomer includes at least one of L-lactide, D-lactide, or meso-lactide; the catalyst has a mass of 0.003-0.008 parts per 100 parts of monomer; the catalyst includes, but is not limited to, a tin-containing catalyst (e.g., stannous octoate); the reaction includes a first stage and a second stage performed sequentially; the reaction temperature of the first stage is 120-140°C, the pressure is 1000-1400 Pa, and the time is 2-6 h; the reaction temperature of the second stage is 165-185°C, the pressure is 200-400 Pa, and the time is 4-8 h; the reaction is followed by pelleting, crystallization, and drying.

[0042] Preferably, the nucleating agent has a D 98 The value is 2 to 30 μm, for example, it can be a range of 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm or any two of these; more preferably it is 4 to 20 μm.

[0043] In this invention, the nucleating agent's D 98 The particle size was determined according to GB / T 19077.1-2008 "Particle size analysis by laser diffraction".

[0044] Preferably, the nucleating agent includes at least one of talc, montmorillonite, zeolite or barium sulfate, more preferably talc and / or montmorillonite.

[0045] In this invention, the nucleating agent can be obtained by purchasing commercially available products or by preparing them using conventional methods. For example, the preparation method includes grinding a commercially available nucleating agent with a large particle size.

[0046] Preferably, the filler comprises at least one of calcium carbonate, diatomaceous earth, wollastonite, kaolin, or mica powder.

[0047] In this invention, the average particle size of the filler is 0.01~20μm, for example, it can be 0.5~15μm.

[0048] In this invention, the average particle size of the filler can be determined by referring to the method of GB / T 19077.1-2008 "Particle size analysis by laser diffraction".

[0049] Preferably, the biodegradable polyester composition further comprises 0.01 to 5 parts by weight of an auxiliary agent, for example, a range of 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 parts or any combination thereof.

[0050] Preferably, the additives include at least one of the following: opening agent, lubricant, antioxidant, compatibilizer, nucleating agent, colorant, or stabilizer.

[0051] 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.

[0052] For example, the opening agent and lubricant can be used to enhance the slip properties (smoothing properties) during the extrusion process and as additives to prevent the film surfaces from adhering to each other; the opening agent and lubricant each independently include, but are not limited to, at least one of ethylene bis-stearamide (EBS), glyceryl monostearate, oleamide, and erucamide; the mass percentage of the opening agent and lubricant in the biodegradable polyester composition can each independently be 0.1-5%.

[0053] 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 antioxidant may be an auxiliary antioxidant, such as tri(nonylphenyl) phosphite and / or dilauryl thiodipropionate; the antioxidant may be present in the biodegradable polyester composition at a mass percentage of 0.1-5%.

[0054] Exemplarily, the compatibilizer is an additive used to impart compatibility by removing the multiphase components of biodegradable polyester, polylactic acid, and thermoplastic 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 biodegradable polyester composition can be 0.1% to 5%.

[0055] 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 biodegradable polyester composition can be 0.1-5%.

[0056] 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 biodegradable polyester composition can be 0.1% to 5%.

[0057] In this invention, the preparation method of the biodegradable polyester composition is not excessively limited; it can be prepared by conventional methods, including but not limited to the following methods: Nucleating agent, polylactic acid, and 30-70% polyester, along with optional additives, are premixed at 200-500 rpm to obtain a premix. The premix and the remaining polyester are fed into the main feed port of a twin-screw extruder, and the filler is fed into the side feed port. The mixture is melt-extruded and granulated at 150-200°C, cooled, and air-dried to obtain the biodegradable polyester composition.

[0058] In a second aspect, the present invention provides a polyester film or bag prepared using the biodegradable polyester composition described in the first aspect.

[0059] Preferably, the method for preparing the polyester film bag includes blown film forming.

[0060] Preferably, the blown film output per unit area during the blown film forming process of the polyester film bag is 20~30 kg / h·mm. 2 .

[0061] 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.

[0062] Compared with the prior art, the beneficial effects of the present invention are as follows: The biodegradable polyester composition provided by the present invention utilizes a method that controls the ratio of the low-frequency composite viscosity to the high-frequency composite viscosity of the polyester within a specific range, which facilitates rapid cooling and shaping of the film bubble during the blown film forming process and increases blown film production. Detailed Implementation

[0063] 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.

[0064] In this invention, the low-frequency composite viscosity (V) L The composite viscosity (V) refers to the composite viscosity at 0.01 Hz. High-frequency composite viscosity (V) H The composite viscosity at 100 Hz is used; the test temperature is 150 ℃; the specific test method includes: pressing polyester into 3 mm sheets using a sheeting machine, placing them in a rotational rheometer (discovery HR-2 rheometer), equilibrating at 150 ℃ for 5 min, and then performing a strain scan experiment with a strain of 1.0% and a shear rate from 0.01 Hz to 100 Hz. The composite viscosity at 0.01 Hz and 100 Hz is read, and the ratio of the two is calculated, i.e., V0. L / V H .

[0065] In this invention, the molar content of D-type lactic acid was tested using a gas chromatograph (Agilent Technologies 7890A). The specific method included: placing polylactic acid and methanol (molar ratio of polylactic acid to methanol 1:1.5) in a pressure vessel and subjecting them to transesterification degradation at 150°C for 5 hours. Then, the mixture was analyzed using gas chromatography. The characteristic peak areas of D-lactic acid methyl ester and L-lactic acid methyl ester were integrated, and the molar content of D-type lactic acid in the polylactic acid was obtained by calculating the percentage of the integrated area. The calculation formula is: Molar content of D-type lactic acid = A DML / (A DML +A LML )×100%; where, A DML The peak area of ​​D-methyl lactate; A LML The peak area is methyl lactate. The gas chromatograph parameters were as follows: a polar capillary column was used; carrier gas and flow rate: nitrogen, 2 mL / min; column temperature program: 50℃ for 2 min, then increased to 150℃ at a rate of 10℃ / min, followed by an increase to 280℃ at a rate of 30℃ / min and held for 5 min.

[0066] In this invention, the nucleating agent's D 98 The particle size was determined according to GB / T 19077.1-2008 "Particle size analysis by laser diffraction".

[0067] 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 shown in Tables 1-3.

[0068] Table 1 Table 2 Table 3 Examples 1-32, Comparative Examples 1-5 Examples 1-32 and Comparative Examples 1-5 each provide a biodegradable polyester composition. The formulations of the polyester compositions are shown in Tables 4-7 by weight. Wherein, " / " indicates that the component is not in the formulation. The preparation method of the polyester composition includes: premixing a nucleating agent, polylactic acid, and 50% of the formulated amount of polyester and optional other auxiliaries at 300 rpm to obtain a premix; feeding the premix and the remaining polyester into the main feed port of a twin-screw extruder, feeding the filler into the side feed port, melt-extruding and granulating at 190°C, cooling and air-drying to obtain the biodegradable polyester composition.

[0069] Table 4 Table 5 Table 6 Table 7 Performance testing (1) Maximum blown film output: The biodegradable polyester compositions provided in the examples and comparative examples were blown into films with a thickness of 25 μm and a width of 300 mm. The specific process was as follows: a blown film machine was used with a die gap of 1.8 mm, a die diameter of 70 mm, a blow-up ratio of 3.0, a set temperature of 150 °C, and a blown film frequency of 40 Hz. The blown film output was gradually increased until the film bubble became unstable and broke. The blown film mass per hour was recorded at this time. The test was repeated three times and the average value was taken, denoted as Yp, with the unit being kg / h. Then, the blown film mass per unit area per hour (Y) was calculated according to the formula: Y = Yp / (25 μm × 0.001 × 300 mm), with the unit being kg / h·mm. 2 This is the limit blown film production.

[0070] The specific test results are shown in Table 8.

[0071] Table 8 As shown in Table 8, the biodegradable polyester composition provided by this invention, by controlling the ratio of the low-frequency composite viscosity to the high-frequency composite viscosity of the polyester within a specific range, facilitates rapid cooling and shaping of the film bubble during the blown film forming process, maintains film bubble stability, and increases blown film yield; the maximum blown film yield of the biodegradable polyester composition during the blown film forming process is 20~30 kg / h·mm. 2 .

[0072] As can be seen from Examples 1 and 7-11, the low-frequency composite viscosity of the polyester is in the range of 1000-5000 Pa•s, which is beneficial to further improve the limit blown film yield of the biodegradable polyester composition in the blown film process.

[0073] As can be seen from Examples 7 and 20, the use of aliphatic-aromatic copolyesters is beneficial to further improve the maximum blown film yield of biodegradable polyester compositions during the blown film process.

[0074] As can be seen from Examples 1 and 23-27, using PLLA-PDLA copolymer with a D-type content of 0.1-5% is beneficial to further improve the maximum blown film yield of biodegradable polyester compositions during the blown film process.

[0075] As can be seen from Examples 1 and 30-32, D is used. 98 It is a nucleating agent with a diameter of 2~30μm, which is beneficial to further improve the maximum blown film yield of biodegradable polyester compositions during the blown film process.

[0076] As can be seen from Comparative Examples 1-5, the ratio of the low-frequency composite viscosity to the high-frequency composite viscosity of the polyester is not in the range of 2 to 100, and the maximum blown film yield of the biodegradable polyester composition is significantly reduced during the blown film process.

[0077] 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 composition, characterized in that, The biodegradable polyester composition comprises, by weight, 40-93 parts polyester, 2-20 parts polylactic acid, 5-40 parts filler and 0.5-5 parts nucleating agent; The ratio of the low-frequency composite viscosity to the high-frequency composite viscosity of the polyester is 2 to 100.

2. The biodegradable polyester composition according to claim 1, characterized in that, The ratio of the low-frequency composite viscosity to the high-frequency composite viscosity of the polyester is 4 to 80, preferably 6 to 50. Preferably, the low-frequency composite viscosity of the polyester is 1000~5000 Pa•s, more preferably 1400~4200 Pa•s, and even more preferably 1800~2800 Pa•s.

3. The biodegradable polyester composition according to claim 1 or 2, characterized in that, The polyester includes aliphatic-aromatic copolyesters and / or aliphatic polyesters, preferably aliphatic-aromatic copolyesters; Preferably, the aliphatic-aromatic copolyester comprises any one or a combination of at least two of polybutylene adipate, polybutylene sebacic acid, and polybutylene succinate. Preferably, the aliphatic polyester comprises polybutylene succinate.

4. The biodegradable polyester composition according to any one of claims 1 to 3, characterized in that, The polylactic acid includes at least one of poly-D-lactic acid, poly-L-lactic acid, or a copolymer of D-lactic acid and L-lactic acid, more preferably a copolymer of D-lactic acid and L-lactic acid.

5. The biodegradable polyester composition according to any one of claims 1 to 4, characterized in that, The polylactic acid is selected from D-lactic acid and L-lactic acid copolymers, wherein the D-lactic acid and L-lactic acid copolymers include a first D-lactic acid and L-lactic acid copolymer and / or a second D-lactic acid and L-lactic acid copolymer, more preferably a first D-lactic acid and L-lactic acid copolymer; Preferably, the molar content of D-lactic acid in the first D-lactic acid and L-lactic acid copolymer is 0.1-5%, more preferably 0.5-4%; Preferably, the molar content of D-lactic acid in the second D-lactic acid and L-lactic acid copolymer is 85-99%, more preferably 93-98%.

6. The biodegradable polyester composition according to any one of claims 1 to 5, characterized in that, The nucleating agent D 98 The thickness is 2~30μm, more preferably 4~20μm; Preferably, the nucleating agent includes at least one of talc, montmorillonite, zeolite or barium sulfate, more preferably talc and / or montmorillonite.

7. The biodegradable polyester composition according to any one of claims 1 to 6, characterized in that, The filler includes at least one of calcium carbonate, diatomaceous earth, wollastonite, kaolin, or mica powder.

8. The biodegradable polyester composition according to any one of claims 1 to 7, characterized in that, The biodegradable polyester composition further includes 0.01 to 5 parts by weight of additives; Preferably, the additives include at least one of the following: opening agent, lubricant, antioxidant, compatibilizer, nucleating agent, colorant, or stabilizer.

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

10. The polyester film or bag according to claim 9, characterized in that, The method for preparing the polyester film or bag includes blown film forming; Preferably, the blown film output per unit area during the blown film forming process of the polyester film bag is 20~30 kg / h·mm. 2 .

Images