Biodegradable polyester composition, and preparation method therefor and use thereof

Abstract

A biodegradable polyester composition, and a preparation method therefor and the use thereof, belonging to the technical field of polymer engineering plastics. The biodegradable polyester composition comprises the following components in parts by mass: 13-88 parts of biodegradable polyester, 13-88 parts of starch, and 2-42 parts of polyhydric alcohol. The biodegradable polyester composition yields a product with a high transparency when subsequently used to prepare a film with a thickness of 12 μm or more. Moreover, the tensile strength, dart impact strength and heat-sealing performance are effectively enhanced.

Description

A biodegradable polyester composition, its preparation method and application Technical Field

[0001] This invention belongs to the field of polymer engineering plastics technology, and particularly relates to a biodegradable polyester composition, its preparation method and application. Background Technology

[0002] Bio-based materials, as a key project for green and sustainable energy development, have received significant attention from the government and industry leaders. With the continuous success of scientific research breakthroughs, bio-based products will undoubtedly play a greater role in achieving the "dual carbon" goals in the future.

[0003] Adding natural macromolecular materials such as starch to increase bio-based content is an important means of reducing costs and carbon emissions. However, starch filling, especially high-starch filling (defined as a starch mass percentage ≥15% in the product), poses significant challenges to product performance and processing technology. High-starch-based biodegradable films have long been favored by the market due to their advantages such as low cost, high bio-based content, and compostability. However, in existing technologies, high-starch films in practical applications such as fruit and vegetable bags and supermarket shopping bags suffer from insufficient transparency (thickness ≥12μm), causing difficulties in identifying and pricing the contents, resulting in application defects. Furthermore, they also exhibit problems such as low impact strength and poor heat-sealing performance. Summary of the Invention

[0004] This invention provides a biodegradable polyester composition with high transparency and excellent mechanical properties obtained when used in the preparation of film products, as well as its preparation method and application.

[0005] This invention provides a biodegradable polyester composition comprising the following components in parts by weight:

[0006] Biodegradable polyester 13-88 parts, starch 13-88 parts, polyhydroxy alcohol 2-42 parts;

[0007] The ratio R of the integral value J1 of the proton signal in the 1H NMR spectrum between 5.0-5.3 ppm to the integral value J2 of the proton signal in the 8.0-8.2 ppm range of the biodegradable polyester. J It ranges from 0.05 to 0.35;

[0008] The ratio R of the dynamic light scattering multi-peak particle size D50 value D1 measured after dispersing the starch in water as a solvent to the D50 value D2 measured after dispersing it in ethanol as a solvent. D ≥1.3;

[0009] The functionality of the polyhydroxy alcohol is ≥2;

[0010] The mass ratio of the biodegradable polyester to starch is ≥1.

[0011] In some embodiments, the biodegradable polyester composition comprises the following components in parts by weight: 50-80 parts of biodegradable polyester, 20-50 parts of starch, and 10-20 parts of polyhydroxy alcohol.

[0012] In some embodiments, the ratio R of the dynamic light scattering multi-peak particle size D50 value D1 measured after the starch is dispersed in water as a solvent to the D50 value D2 measured after it is dispersed in ethanol as a solvent is... D It is 1.30-1.50.

[0013] In some embodiments, the functionality of the polyhydroxy alcohol is 3-6.

[0014] In some embodiments, the biodegradable polyester includes aliphatic polyesters and aliphatic-aromatic copolyesters.

[0015] In some embodiments, the aliphatic-aromatic copolyester comprises at least one aromatic dicarboxylic acid selected from terephthalic acid and furanyl dicarboxylic acid, and at least one aliphatic dicarboxylic acid selected from adipic acid, succinic acid, azelaic acid, sebacic acid, and brassic acid, which are polycondensed with at least one diol selected from propylene glycol and butanediol.

[0016] In some embodiments, the aliphatic polyester comprises polylactic acid, and the content of the dextrorotatory monomer in the aliphatic polyester is 1-15%.

[0017] In some embodiments, the starch includes at least one of natural starch and natural starch derivatives.

[0018] The present invention provides a method for preparing the biodegradable polyester composition, comprising the following steps: weighing and mixing the dried raw materials and feeding them into a twin-screw extruder, and extruding, stretching, cooling, pelletizing and drying to obtain the biodegradable polyester composition.

[0019] This invention provides the application of the described biodegradable polyester composition in the preparation of biodegradable film products.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The present invention provides a biodegradable polyester composition in which the integral value J1 of the proton signal between 5.0-5.3 ppm and the integral value J2 of the proton signal between 8.0-8.2 ppm are used. J The ratio R of the D50 value D1 of a biodegradable polyester dispersed in water to the D50 value D2 dispersed in ethanol within a specific range. DWithin a specific range, starch and polyhydroxy alcohol synergistically enhance the transparency and mechanical properties of the biodegradable polyester composition by means of synergistic effects within the given mass fractions. Furthermore, the preparation method of the biodegradable polyester composition provided by this invention is simple to operate and beneficial for practical applications. Detailed Implementation

[0022] The term "biodegradable polyester" refers to a class of polymeric materials that can be decomposed by microorganisms in the natural environment, ultimately degrading into carbon dioxide (or methane), water, biomass, and inorganic salts. Polyesters are synthetic polymers formed by the condensation polymerization of polyols and polyacids, and their molecular chains contain a large number of ester (-COO-) functional groups.

[0023] The term "integral value of the proton signal" (i.e., the integrated value of the proton signal in 1H NMR spectroscopy as described herein) refers to the area covered below the signal peak produced by a hydrogen atom (¹H) in 1H NMR spectroscopy. This area (i.e., the integrated value) is typically obtained directly through instrumentation or software detection or calculation. The area is proportional to the number of equivalent hydrogen atoms that produce the spectral peak, providing direct information about the number of different types of hydrogen atoms in a compound, and can be used to resolve the compound's structure.

[0024] The term "Dynamic Light Scattering Multi-peak Particle Size D50 Value" refers to the particle size distribution in a sample exhibiting multiple peaks during dynamic light scattering (DLS) measurements, where 50% of the particles have a diameter smaller than the critical particle size, which is the D50 value.

[0025] The term "functionality of polyhydroxy alcohols" refers to the number of hydroxyl groups (-OH) in their molecules.

[0026] To achieve the above objectives, in a first aspect, the present invention provides a biodegradable polyester composition comprising the following components in parts by weight:

[0027] Biodegradable polyester 13-88 parts, starch 13-88 parts, polyhydroxy alcohol 2-42 parts;

[0028] The ratio R of the integral value J1 of the proton signal in the 1H NMR spectrum between 5.0-5.3 ppm to the integral value J2 of the proton signal in the 8.0-8.2 ppm range of the biodegradable polyester. J It ranges from 0.05 to 0.35;

[0029] The ratio R of the dynamic light scattering multi-peak particle size D50 value D1 measured after dispersing the starch in water as a solvent to the D50 value D2 measured after dispersing it in ethanol as a solvent. D ≥1.3;

[0030] The functionality of the polyhydroxy alcohol is ≥2;

[0031] The mass ratio of the biodegradable polyester to starch is ≥1.

[0032] The biodegradable polyester composition provided by this invention, by selecting appropriate mass fractions of components, can avoid the problem of gaps easily appearing between the continuous and dispersed phases due to the difference in thermal expansion and contraction rates caused by high starch content, even when preparing high starch-based biodegradable films (starch mass percentage ≥ 15%). In other words, the technical solution provided by this invention promotes compatibility between the two phases, thereby reducing the refractive index and diffuse reflection of the composition, and thus improving the transparency of the subsequently prepared film product. Even when the thickness of the subsequently prepared film product is 12 μm or more, the transparency of the product still meets the requirements for practical applications. Furthermore, the reasonable combination of components can also effectively improve the mechanical properties of the composition, specifically, the tensile strength, dart impact strength, and heat-sealing performance of the obtained product are all high.

[0033] It is understood that, apart from the differences in the ranges of 5.0-5.3 ppm and 8.0-8.2 ppm, the other test conditions for J1 and J2 are the same. It is also understood that, apart from the difference in the dispersion solvent (water or ethanol), the other test conditions for the two D50 values ​​(i.e., D1 and D2) are the same.

[0034] Specifically, the ratio R of the integral value J1 of the proton signal in the 1H NMR spectrum of biodegradable polyester between 5.0 and 5.3 ppm to the integral value J2 of the proton signal in the 8.0-8.2 ppm range is... J A value of 0.05-0.35 indicates that the ratio of aliphatic polyesters to aliphatic-aromatic copolyesters in biodegradable polyesters is appropriate, effectively co-producing with R. D Within a certain range, the interaction between starch and polyhydroxy alcohols improves the compatibility between components and avoids the problem of increased gap ratio between the dispersed and continuous phases due to differences in thermal expansion and contraction rates caused by the introduction of excessive starch during the preparation process. Simultaneously, the ratio R of the D50 value D1 of starch dispersed in water to the D50 value D2 of starch dispersed in ethanol is also considered. D A concentration of ≥1.3 can result in a greater equilibrium water absorption rate, further reducing the gap ratio between the two phases; thereby improving the transparency, mechanical properties, and thermal sealing properties of the film products prepared using this composition.

[0035] In some embodiments, the method for testing the 1H NMR spectrum of the biodegradable polyester composition may include the following steps: preparing a test solution of 5 mg / mL using deuterated chloroform as a solvent, measuring the solution using an Ascend 600 NMR spectrometer at a test temperature of 25°C, adding TMS (tetramethylsilane) as an internal standard to the deuterated reagent, and performing 32 scans. In some embodiments, after scanning, the spectrum is automatically integrated using MestReNova software to calculate the ratio of J1 to J2, thereby obtaining R. J Value range.

[0036] For example, the R J It can be any point value between 0.05 and 0.35 or a range value composed of any two points, such as 0.10-0.30, 0.1-0.15, etc., or 0.05, 0.07, 0.09, 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, 0.22, 0.24, 0.26, 0.28, 0.30, 0.32, 0.34, 0.35, etc., or a range value composed of any two of the aforementioned point values.

[0037] It should be noted that the dynamic light scattering multi-peak particle size D50 obtained in this invention refers to Dv50. In some embodiments, the method of obtaining starch in the biodegradable polyester composition may include the following steps: dissolving the biodegradable polyester composition with dichloromethane, then centrifuging, collecting the precipitate and washing it with dichloromethane to obtain starch. Subsequently, it is dispersed in water or ethanol as solvents and then tested. In some embodiments, the method for testing the D50 value of starch dispersed in water may include the following steps: taking 1g of starch and using 100mL of deionized water as the dispersion phase, stirring for 5min, and then testing and recording the multi-peak particle size D50 value on a Mastersizer laser particle size analyzer; the method for testing the D50 value of starch dispersed in ethanol may include the following steps: taking 1g of starch and using 100mL of ethanol as the dispersion phase, stirring for 5min, and then testing and recording the multi-peak particle size D50 value on a Mastersizer laser particle size analyzer; then calculating the ratio R of the D50 value D1 of starch dispersed in water to the D50 value D2 of starch dispersed in ethanol. D .

[0038] For example, the R D The value can be any point value between ≥1.3 or a range value composed of any two points, such as 1.3-1.8, or 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, etc., or a range value composed of any two of the stated point values.

[0039] In some embodiments, the dynamic light scattering multi-peak particle size D50 value D1 is ≤ 50 nm when the starch is dispersed in water as a solvent, and the D50 value D2 is ≤ 40 nm when dispersed in ethanol as a solvent.

[0040] For example, the mass ratio of the biodegradable polyester to starch can be any point value ≥1 or a range of any two points, such as 1-2.5, 1-1.6, 1-2, etc., or 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, etc., or a range of any two of the above point values.

[0041] In some embodiments, the ratio R of the integral value J1 of the proton signal in the proton NMR spectrum between 5.0 and 5.3 ppm to the integral value J2 of the proton signal in the proton NMR spectrum between 8.0 and 8.2 ppm is... J It ranges from 0.1 to 0.15.

[0042] In some embodiments, the starch content in the biodegradable polyester composition is 15-50% by mass.

[0043] For example, the biodegradable polyester can be any point value or any range of two points between 13 and 88 parts, such as 15-85 parts, or 13, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 88 parts, etc., or any range of two such point values; the starch can be any point value or any range of two points between 13 and 88 parts, such as 15-85 parts, or 13, 15, 20, 25, 30 parts, etc. The range of values ​​can be 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 88, or any two of the stated values; the polyhydroxy alcohol can be any value between 2 and 42, or any two of the stated values, for example, 3-41, or 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, or any two of the stated values.

[0044] In some embodiments, the biodegradable polyester composition comprises the following components in parts by weight: 50-80 parts of biodegradable polyester, 20-50 parts of starch, and 10-20 parts of polyhydroxy alcohol.

[0045] This invention has found that the mass fraction of added components affects the performance of the product. When the mass fraction of the components is further selected within the above-mentioned range, the overall effect of the product is even better.

[0046] In some embodiments, the ratio R of the D50 value D1 of the starch dispersed in water as a solvent to the D50 value D2 of the starch dispersed in ethanol as a solvent is... D It is 1.30-1.50.

[0047] This invention has found that the ratio R of the D50 value D1 of starch dispersed in water to the D50 value D2 of starch dispersed in ethanol is... D To some extent, it reflects the equilibrium water absorption rate of starch, and R D The value of R also affects the shear dispersion of starch during the preparation process; when further selecting R... D When the ratio is 1.30-1.50, the resulting composition, when used in the preparation of thin film products, produces thin film products with higher transparency, tensile strength, dart impact strength, and heat-sealing performance.

[0048] For example, the R D The value can be any point value between 1.30 and 1.50 or a range value composed of any two points. For example, it can be 1.30, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.40, 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49, 1.50, etc., or a range value composed of any two of the aforementioned point values.

[0049] In some embodiments, the functionality of the polyhydroxy alcohol is 3-6.

[0050] This invention has found that the hydroxyl groups in polyhydroxy alcohols can affect the compatibility between biodegradable polyesters and starch, thereby affecting the overall performance of the product. When the functionality of the polyhydroxy alcohol is further selected to be 3-6, the overall performance of the product is better.

[0051] For example, the functionality of the polyhydroxy alcohol can be any point value between 3 and 6 or a range of any two points, such as 3, 4, 5, 6, or any range of two points.

[0052] In some embodiments, the polyhydroxy alcohol includes at least one selected from glycerol, diglycerol, triglycerol, tetraglycerol, ethylene glycol, pentaglycerol, and sorbitol.

[0053] In some embodiments, the biodegradable polyester includes aliphatic polyesters and aliphatic-aromatic copolyesters.

[0054] When the biodegradable polyester comprises aliphatic polyester and aliphatic-aromatic copolyester, the present invention does not have special requirements on the mass ratio of aliphatic polyester and aliphatic-aromatic copolyester, and can be conventionally selected according to actual conditions. In some embodiments, the mass ratio can be in the range of 1:(2.9-109).

[0055] In some embodiments, the aliphatic-aromatic copolyester comprises at least one aromatic dicarboxylic acid selected from terephthalic acid and furanyl dicarboxylic acid, and at least one aliphatic dicarboxylic acid selected from adipic acid, succinic acid, azelaic acid, sebacic acid, and brassic acid (i.e., tridecanoic acid), which is polycondensed with at least one diol selected from propylene glycol and butanediol.

[0056] This invention does not place particular requirements on the molar ratio of aromatic diacids to aliphatic diacids in aliphatic-aromatic copolyesters, and can be conventionally selected according to actual conditions. In some embodiments, the molar ratio is in the range of 0.5-2, which achieves the purpose of this invention. This invention does not place particular requirements on the melt flow rate of aliphatic-aromatic copolyesters, and can be conventionally selected according to actual conditions. In some embodiments, the melt flow rate is in the range of 1-20 g / 10 min, which achieves the purpose of this invention; wherein, the melt flow rate test method for aliphatic-aromatic copolyesters is GB / T 3682-2000, and the test conditions are 190℃ and 2.16 kg.

[0057] This invention has found that the type of biodegradable polyester also affects the performance of the product. When the biodegradable polyester includes aliphatic polyester and aliphatic-aromatic copolyester, especially in some embodiments, when the aliphatic-aromatic copolyester is further selected as follows: it contains at least one aromatic dicarboxylic acid selected from terephthalic acid and furanyl dicarboxylic acid, and at least one aliphatic dicarboxylic acid selected from adipic acid, succinic acid, azelaic acid, sebacic acid, and brassic acid, and is a copolyester formed by polycondensation with at least one diol selected from propylene glycol and butanediol; the resulting product has higher transparency and better mechanical properties.

[0058] In some embodiments, the aliphatic polyester comprises polylactic acid, and the content of the dextrorotatory monomer in the aliphatic polyester is 1-15%. In some embodiments, the content of the dextrorotatory monomer in the aliphatic polyester is 6-15%. It is understood that because the optical isomers have the same mass, the "content of dextrorotatory monomer" is the same whether it is mass content or molar content (or proportion). In some embodiments, it refers to molar content.

[0059] The present invention has found that when the mass content of the dextrorotatory monomer in the aliphatic polyester is further selected to be 6-15%, the compatibility between the components is better, the gap ratio between the dispersed phase and the continuous phase during the preparation process is lower, which can effectively reduce the light refractive index and diffuse reflection of the film product obtained in the subsequent preparation, improve the transparency of the film product, and the excellent compatibility between the components can also improve the mechanical properties and thermal sealing properties of the product.

[0060] For example, the content of the aliphatic polyester dextrorotatory monomer can be any point value between 6% and 15% or a range of any two points, such as 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc. or a range of any two points.

[0061] This invention does not have special requirements for the weight-average molecular weight of polylactic acid (PLA), which can be conventionally selected according to actual conditions. In some embodiments, the weight-average molecular weight of PLA is in the range of 30,000-120,000, which can achieve the purpose of this invention; wherein, the weight-average molecular weight of PLA is determined according to the standard method of YY / T 1678-2019.

[0062] In some embodiments, the starch includes at least one of natural starch and natural starch derivatives.

[0063] For example, the natural starch includes at least one of corn starch, potato starch, rice starch, and tapioca starch; the natural starch derivative includes at least one of natural starch esters, natural starch ethers, and natural starch oxides.

[0064] It should be noted that, without affecting the effect of the biodegradable polyester composition described in this invention, additives such as antioxidants, antistatic agents, weathering agents, lubricants, opening agents, and colorants may be added as needed.

[0065] The biodegradable polyester composition of the present invention can be prepared using conventional methods in the art.

[0066] In a second aspect, the present invention provides a method for preparing a biodegradable polyester composition, the method comprising the following steps: weighing and mixing dried raw materials and feeding them into a twin-screw extruder, followed by extrusion, stranding, cooling, pelletizing, and drying to obtain a biodegradable polyester composition.

[0067] In some embodiments, during the extrusion, the screw length-to-diameter ratio is 40:1, and the set temperatures are: Zone 1: 60-90℃, Zone 2: 100-130℃, Zone 3: 140-170℃, Zone 4: 150-190℃, Zone 5: 150-190℃, Zone 6: 150-190℃, Zone 7: 150-190℃, Zone 8: 150-190℃, Zone 9: 150-190℃, Die head: 150-190℃, Screw speed: 250-350 rpm, and Extrusion speed: 400-600 kg / h.

[0068] In some embodiments, the present invention provides a biodegradable polyester composition, which uses the biodegradable polyester, starch, and polyhydroxy alcohol described in this application as raw materials, comprising the aforementioned parts by weight; the dried raw materials are weighed and mixed and fed into a twin-screw extruder, and after extrusion, stretching, cooling, pelletizing, and drying, the biodegradable polyester composition is obtained.

[0069] In a third aspect, the present invention provides the use of the biodegradable polyester composition in the preparation of biodegradable film products.

[0070] This invention provides a biodegradable film product derived from (or prepared from, or formed from) the biodegradable polyester composition. Non-limiting examples of the biodegradable film product include shopping bags, agricultural mulch films, food packaging films, garbage bags, disposable product packaging films, industrial stretch films, etc. The term "derived" (or "prepared," or "formed") refers to a film product obtained through conventional processes that can be used in this invention, including but not limited to one or more of extrusion, blow molding, and casting.

[0071] In some embodiments, typically, the biodegradable polyester composition does not undergo chemical change during the derivatization (or preparation, or formation) of a biodegradable film product (i.e., the biodegradable film product comprises the biodegradable polyester composition). In other embodiments, the material of the biodegradable polyester composition may undergo chemical change during the derivatization (or preparation, or formation) of the biodegradable film product.

[0072] In some embodiments, the biodegradable film product is derived (or prepared, or formed) solely from the material of the biodegradable polyester composition. In other embodiments, other additives (e.g., at least one of colorants, compatibilizers, lubricants, processing aids, anti-hydrolysis agents, antioxidants) may be used in the process of deriving (or preparing, or forming) the biodegradable film product.

[0073] For example, the biodegradable film products include any one of shopping bags, kitchen waste bags, food packaging films, and agricultural mulch films.

[0074] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0075] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in the field.

[0076] Aliphatic polyester 1: polylactic acid, with a dextrorotatory monomer content of 8%, KB600 NF50, Zhuhai Kingfa Biomaterials Co., Ltd.;

[0077] Aliphatic polyester 2: polylactic acid, 1% dextrorotatory monomer content, KB600 NF10, Zhuhai Kingfa Biomaterials Co., Ltd.;

[0078] Aliphatic-aromatic copolyester 1: Polybutylene terephthalate-adipate, KB100, Zhuhai Kingfa Biomaterials Co., Ltd.;

[0079] Aliphatic-aromatic copolyester 2: Polybutylene terephthalate-sebate, A300, Zhuhai Kingfa Biomaterials Co., Ltd.;

[0080] Biodegradable polyester 1:R J The ratio is 0.15, and it is a mixture formed by aliphatic polyester 1 and aliphatic-aromatic copolyester 1 at a ratio of 1:10;

[0081] Biodegradable polyester 2:R J The mixture is 0.1% aliphatic polyester 1 and aliphatic-aromatic copolyester 1 in a ratio of 1:14.7.

[0082] Biodegradable polyester 3:R J The mixture is 0.05% aliphatic polyester 1 and aliphatic-aromatic copolyester 1 in a ratio of 1:32.3.

[0083] Biodegradable polyester 4:R J The ratio is 0.35, and it is a mixture of aliphatic polyester 1 and aliphatic-aromatic copolyester 1 in a ratio of 1:4;

[0084] Biodegradable polyester 5:R J The ratio is 0.15, and it is a mixture formed by aliphatic polyester 2 and aliphatic-aromatic copolyester 1 at a ratio of 1:10;

[0085] Biodegradable polyester 6:R J The ratio is 0.15, and it is a mixture formed by aliphatic polyester 1 and aliphatic-aromatic copolyester 2 at a ratio of 1:10;

[0086] Biodegradable polyester 7:R J The ratio is 0.01, and it is a mixture formed by aliphatic polyester 1 and aliphatic-aromatic copolyester 1 at a ratio of 1:109;

[0087] Biodegradable polyester 8:R J The ratio is 0.4, and the mixture is formed by aliphatic polyester 1 and aliphatic-aromatic copolyester 1 at a ratio of 1:2.9; the ratio of aliphatic polyester and aliphatic-aromatic copolyester in the biodegradable polyesters 1-8 mentioned above is a mass ratio.

[0088] Starch 1: BENEFORM 2260, Ingredion, USA;

[0089] Starch 2: BENEFORM 2160, Ingredion, USA;

[0090] Starch 3: Corn starch, Shandong Shouguang Juneng Jin Corn Development Co., Ltd.;

[0091] Starch 4: ZYT-201, Hangzhou Zhiyou Technology Co., Ltd.;

[0092] Starch 5: Potato starch, Guyuan County Baishunyuan Starch Co., Ltd.;

[0093] Polyhydroxy alcohol 1: Glycerin, functionality 3, commercially available;

[0094] Polyhydroxy alcohol 2: Sorbitol, functionality 6, commercially available;

[0095] Polyhydroxy alcohol 3: ethylene glycol, functionality 2, commercially available;

[0096] Polyhydroxy alcohol 4: pentaglycerol, functionality 7, commercially available.

[0097] Examples 1-15 and Comparative Examples 1-5

[0098] The present invention provides a biodegradable polyester composition in embodiments and comparative examples. The components (parts by weight) of the biodegradable polyester composition are shown in Tables 1-2, wherein R D To separate starch from the biodegradable polyester compositions prepared in the corresponding examples and comparative examples, the ratio R of the D50 value D1 of starch dispersed in water as a solvent to the D50 value D2 of starch dispersed in ethanol as a solvent was tested. D ;

[0099] Table 1

[0100] Table 2

[0101] The method for preparing the biodegradable polyester composition provided in Example 1 includes the following steps:

[0102] First, the biodegradable polyester is dried in an oven at 80℃ for 5 hours. Then, it is mixed with starch and polyhydroxy alcohol in a high-speed mixer for 3 minutes. The resulting homogeneous mixture is fed into a twin-screw extruder for melt plasticization, extrusion, and granulation to obtain a biodegradable polyester composition. The twin-screw extruder is a co-rotating parallel twin-screw extruder with a screw length-to-diameter ratio of 40:1. Its set temperatures are: Zone 1: 80℃, Zone 2: 110℃, Zone 3: 150℃, Zone 4: 180℃, Zone 5: 180℃, Zone 6: 180℃, Zone 7: 180℃, Zone 8: 180℃, Zone 9: 180℃, Die head: 180℃, Screw speed: 300 rpm, Extrusion speed: 500 kg / h.

[0103] The preparation methods of the biodegradable polyester compositions provided in Examples 2-15 and Comparative Examples 1-5 are consistent with those in Example 1, except that the relevant components are not added.

[0104] Example of effect

[0105] The effectiveness examples of this invention verify the performance of the biodegradable polyester compositions prepared in Examples 1-15 and Comparative Examples 1-5. The biodegradable polyester compositions prepared in the examples and comparative examples were fabricated into films using a single-screw blown film mill with a screw diameter of 45 cm and an aspect ratio of 20:1. Specifically, a thickness calibrator was used to control the same apparent thickness, and the average apparent thickness was tested according to ISO 4593-1993 standard, finding to be 12 μm. Subsequently, the prepared films underwent performance testing, including the following aspects:

[0106] 1) Transparency test: The film was cut into samples with a diameter of 7cm and stabilized in an environment of 23±3℃ and 50±5RH% humidity for 1 hour. Then, the transmittance and haze values ​​were tested by the Shanghai Shenguang WGT-S transmittance and haze meter. The test was performed in parallel for 3 times and the average value was taken to obtain the transmittance and haze.

[0107] 2) Tensile strength: The test was conducted according to the standard method of GB / T 1040.3-2006. The test speed was (500±50) mm / min. The transverse tensile strength and longitudinal tensile strength of the film were recorded.

[0108] 3) Dart impact strength: Tested according to the standard method of GB / T 9639.1-2008;

[0109] 4) Heat sealing strength: Tested according to the standard method of QB / T 2358-1998, with a test speed of (300±50) mm / min.

[0110] The results are shown in Table 3.

[0111] Table 3

[0112] As can be seen from Table 3, when the technical solution of the present invention is adopted, the film formed by the biodegradable polyester composition has excellent transparency and mechanical properties. Specifically, when the film with an average apparent thickness of 12 μm is prepared using the biodegradable polyester composition, the light transmittance is above 86%, the haze is below 45%, the longitudinal tensile strength is above 20 MPa, the transverse tensile strength is above 16 MPa, the dart impact strength is above 165 g, and the heat sealing strength is above 15 N / 15 mm.

[0113] As can be seen from Examples 1, 5-9 and Comparative Examples 1-2, the selection of biodegradable polyester affects the overall performance of the product. When the parameters of the biodegradable polyester are further selected within the range given in this invention, the overall performance of the obtained product is excellent. When the parameters of the biodegradable polyester in Comparative Examples 1-2 are not within the range of this invention, the mechanical properties of the obtained product decrease significantly.

[0114] As can be seen from Examples 1-4 and Comparative Example 3, the mass fraction of the components also has a significant impact. When the mass fraction of starch in Comparative Example 3 is greater than that of biodegradable polyester, the mechanical properties of the obtained product decrease significantly and the light transmittance also decreases.

[0115] As can be seen from Examples 1, 10-12 and Comparative Example 4, the choice of starch also affects the performance of the product. When the parameters of the starch in Comparative Example 4 are not within the scope of the present invention, the overall performance of the obtained product is significantly reduced. As can be seen from Examples 1, 13-15 and Comparative Example 5, when the degree of hydroxyl groups of the alcohols selected in Comparative Example 5 are not within the scope of the present invention, the obtained product also fails to meet the requirements.

[0116] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A biodegradable polyester composition, characterized in that, The biodegradable polyester composition comprises the following components in parts by weight: Biodegradable polyester 13-88 parts, starch 13-88 parts, polyhydroxy alcohol 2-42 parts; The ratio R of the integral value J1 of the proton signal in the 1H NMR spectrum between 5.0-5.3 ppm to the integral value J2 of the proton signal in the 8.0-8.2 ppm range of the biodegradable polyester. J It ranges from 0.05 to 0.35; The ratio R of the dynamic light scattering multi-peak particle size D50 value D1 measured after dispersing the starch in water as a solvent to the D50 value D2 measured after dispersing it in ethanol as a solvent. D ≥1.3; The functionality of the polyhydroxy alcohol is ≥2; The mass ratio of the biodegradable polyester to starch is ≥1.

2. The biodegradable polyester composition according to claim 1, characterized in that, The biodegradable polyester composition comprises the following components in parts by weight: 50-80 parts biodegradable polyester, 20-50 parts starch, and 10-20 parts polyhydroxy alcohol.

3. The biodegradable polyester composition according to claim 1, characterized in that, The ratio R of the dynamic light scattering multi-peak particle size D50 value D1 measured after dispersing the starch in water as a solvent to the D50 value D2 measured after dispersing it in ethanol as a solvent. D It is 1.30-1.

50.

4. The biodegradable polyester composition according to claim 1, characterized in that, The functionality of the polyhydroxy alcohol is 3-6.

5. The biodegradable polyester composition according to claim 1, characterized in that, The biodegradable polyesters include aliphatic polyesters and aliphatic-aromatic copolyesters.

6. The biodegradable polyester composition according to claim 5, characterized in that, The aliphatic-aromatic copolyester comprises at least one aromatic dicarboxylic acid selected from terephthalic acid and furanyl dicarboxylic acid, and at least one aliphatic dicarboxylic acid selected from adipic acid, succinic acid, azelaic acid, sebacic acid, and brassic acid, which are polycondensed with at least one diol selected from propylene glycol and butanediol.

7. The biodegradable polyester composition according to claim 5, characterized in that, The aliphatic polyester includes polylactic acid, and the content of dextrorotatory monomer in the aliphatic polyester is 1-15%.

8. The biodegradable polyester composition according to claim 1, characterized in that, The starch includes at least one of natural starch and natural starch derivatives.

9. The method for preparing the biodegradable polyester composition according to any one of claims 1-8, characterized in that, The preparation method includes the following steps: weighing the dried raw materials and mixing them, feeding them into a twin-screw extruder, and extruding, stretching, cooling, pelletizing and drying to obtain a biodegradable polyester composition.

10. The use of the biodegradable polyester composition according to any one of claims 1-8 in the preparation of biodegradable film products.

Images