A biodegradable polyester composition, a method of preparation and use

Abstract

The present application belongs to the field of biodegradable polyester, and particularly relates to a biodegradable polyester composition, a preparation method and application. The biodegradable polyester composition comprises the following components in percentage by weight: i. 75-100% of biodegradable copolyester, based on the total weight of components i-ii; ii. 0-25% of polylactic acid, based on the total weight of components i-ii; iii. 15-30% of acid-erodible inorganic rigid particles, based on the total weight of components i-iv; iv. 1-15% of non-acid-erodible inorganic rigid particles, based on the total weight of components i-iv; the mixed particle size of the acid-erodible inorganic rigid particles and the non-acid-erodible inorganic rigid particles meets the following distribution: D90 < 12 microns, D95 = 15-25 microns. The film prepared by the present application has better mechanical properties and lower apparent density under similar apparent thickness.

Description

Technical Field

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

[0002] Biodegradable polyesters are a class of polymer materials made from biological resources. Compared to petroleum-based polymers made from petrochemical resources, biodegradable polyesters can degrade during biological or biochemical processes or in biological environments, making them one of the most actively researched and commercially successful biodegradable materials. Biodegradable polyester film is one of the important application areas for biodegradable polyesters. Biodegradable polyesters are soft, non-toxic, easy to process, chemically stable, have a certain strength, and exhibit good resistance to chemical solvents and cold. They are widely used in shopping bags, kitchen waste bags, food packaging films, agricultural mulch films, and other fields.

[0003] With increasing demand and tight supply of chemical raw materials, the price of biodegradable polyester has risen sharply. Adding inorganic rigid particles is one of the important means to improve performance and reduce costs. However, existing technologies for obtaining biodegradable polyester by adding inorganic rigid particles cannot achieve low material costs while ensuring good mechanical properties of biodegradable polyester. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a biodegradable polyester composition, its preparation method, and its applications. Films prepared from this biodegradable polyester composition, with similar inorganic content, exhibit better mechanical properties and lower apparent density at the same apparent thickness, which is beneficial for reducing material costs.

[0005] To achieve the above objectives, the present invention employs the following technical solution: a biodegradable polyester composition comprising the following components by weight percentage:

[0006] i. 75 to 100% by weight of biodegradable copolyester, based on the total weight of components i to ii;

[0007] ii. 0 to 25% by weight of polylactic acid, based on the total weight of components i to ii;

[0008] iii. 15–30% by weight of acid-etchable inorganic rigid particles, based on the total weight of components i–iv;

[0009] iv. 1–15% by weight of non-acid-etchable inorganic rigid particles, based on the total weight of components i–iv.

[0010] The mixed particle size of the acid-etchable and non-acid-etchable inorganic rigid particles conforms to the following distribution: D90 < 12 μm, D95 = 15–25 μm. D90 and D95 ​​are determined by the multi-peak particle size distribution of the laser-induced particle size residuals after calcination at 500 °C.

[0011] It is understood that in this invention, D90 < 12 μm can be understood as including but not limited to 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, and 11 μm; D95 = 15 to 25 μm can be understood as including but not limited to 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, and 25 μm.

[0012] Preferably, the mixed particle size of the acid-etchable inorganic rigid particles and the non-acid-etchable inorganic rigid particles conforms to the following distribution: D90≤7.5μm, D95=16.3~21.5μm.

[0013] More preferably, the mixed particle size of the acid-etchable inorganic rigid particles and the non-acid-etchable inorganic rigid particles conforms to the following distribution: D90 = 6.2~7.3μm, D95 = 17.4~20.8μm.

[0014] Preferably, the biodegradable polyester composition comprises the following components in weight percentages:

[0015] i. 90–95% by weight of biodegradable copolyester, based on the total weight of components i–ii;

[0016] ii. 5 to 10% by weight of polylactic acid, based on the total weight of components i to ii;

[0017] iii. 21–24% by weight of acid-etchable inorganic rigid particles, based on the total weight of components i–iv;

[0018] iv. 5–8% by weight of non-acid-etchable inorganic rigid particles, based on the total weight of components i–iv.

[0019] Preferably, the biodegradable copolyester is at least one of a copolymer of butylene adipate and butylene terephthalate, or a copolymer of butylene sebacate and butylene terephthalate.

[0020] More preferably, the molar percentage of butylene adipate and butylene terephthalate in the copolymer is 40-60%; the molar percentage of butylene terephthalate in the copolymer of butylene sebacate and butylene terephthalate is 40-60%.

[0021] Preferably, the biodegradable polyester composition comprises the following two items (1) and (2):

[0022] (1) The acid-etchable inorganic rigid particles refer to inorganic rigid particles that can be completely dissolved in 1M hydrochloric acid; the acid-etchable inorganic rigid particles are at least one of calcium carbonate and calcite.

[0023] (2) The non-acid-etchable inorganic rigid particles refer to inorganic rigid particles that cannot be completely dissolved under 1M hydrochloric acid; the non-acid-etchable inorganic rigid particles include at least one of talc, silicon dioxide, barium sulfate, and titanium dioxide.

[0024] Preferably, the biodegradable polyester composition further includes an opening agent comprising 0-0.5% by weight of the total weight of components i-iv. The opening agent is a common component in the art.

[0025] A method for preparing the biodegradable polyester composition includes the following steps:

[0026] First, biodegradable copolyester and polylactic acid are uniformly mixed and dried. Then, they are stirred and mixed with acid-etchable inorganic rigid particles, non-acid-etchable inorganic rigid particles, and an opening agent. The resulting uniform mixture is melt-plasticized, extruded, and granulated to obtain a biodegradable polyester composition.

[0027] Preferably, the drying temperature is 70–90°C and the drying time is 4–6 hours.

[0028] Preferably, the mixing time is 1 to 5 minutes.

[0029] Preferably, the set temperature for the melt plasticizing, extrusion, and granulation is 60–190°C, the rotation speed is 250–320 rpm, and the extrusion speed is 550–630 kg / h.

[0030] An application of the biodegradable polyester composition in the preparation of biodegradable film products, wherein the biodegradable film products include any one of shopping bags, kitchen waste bags, food packaging films, and agricultural mulch films.

[0031] The acid-etchable inorganic rigid particles selected in this invention exhibit better dispersibility in the weakly acidic environment of biodegradable polyester melt, effectively increasing the toughness of the composition. The non-acid-etchable inorganic rigid particles also demonstrate better dimensional stability in the same environment, effectively increasing the rigidity of the composition. Smaller inorganic rigid particles are more easily encapsulated by the resin matrix, enhancing the continuous phase but significantly increasing the apparent density of the resulting film. Larger inorganic rigid particles are less easily encapsulated by the resin matrix and protrude from the surface of the resulting film, which helps reduce the apparent density but leads to decreased mechanical properties due to disruption of the continuous phase. By adjusting the weight ratio and particle size distribution of acid-etchable and non-acid-etchable inorganic rigid particles, the resulting biodegradable polyester composition can possess good tensile strength, impact strength, and other mechanical properties, while maintaining a low apparent density.

[0032] In this invention, all references to inorganic rigid particles refer to the sum of acid-etchable inorganic rigid particles and non-acid-etchable inorganic rigid particles.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention utilizes inorganic rigid particles with a specific particle size distribution in a biodegradable polyester composition to achieve a mixed particle size distribution that satisfies: D90 < 12 μm, D95 = 15–25 μm. Films made from this biodegradable polyester composition with similar inorganic content exhibit better mechanical properties and lower apparent density at similar apparent thicknesses, effectively reducing material usage and further lowering material costs. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods. Unless otherwise specified, the opening agents are commercially available, and the same one is used in parallel experiments.

[0037] The raw materials used in the examples and comparative examples are shown in Table 1.

[0038] Table 1

[0039]

[0040]

[0041] In this embodiment of the invention, the mixed particle size distributions D90 and D95 ​​of the acid-etchable and non-acid-etchable inorganic rigid particles are adjusted by regulating the weight ratio of the acid-etchable and non-acid-etchable inorganic rigid particles.

[0042] Examples 1-6 and Comparative Examples 1-5

[0043] The components and parts by weight of the biodegradable polyester compositions of Examples 1-6 and Comparative Examples 1-5 are shown in Table 2.

[0044] The preparation methods of the biodegradable polyester compositions of Examples 1-6 and Comparative Examples 1-5 include the following steps:

[0045] First, biodegradable copolyester and polylactic acid are uniformly mixed and dried at 80°C for 5 hours. Then, they are stirred and mixed with acid-etchable inorganic rigid particles, non-acid-etchable inorganic rigid particles, and an opening agent for 3 minutes. The resulting uniform mixture is fed into a twin-screw extruder for melt plasticization, extrusion, and granulation to obtain a biodegradable polyester composition.

[0046] 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: 130℃, 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: 600 kg / h.

[0047] Inorganic rigid particle content and multi-peak particle size determination

[0048] A certain amount of biodegradable polyester composition was placed in a covered crucible and calcined in a muffle furnace at 500°C to constant weight. The total ash content (inorganic rigid particles) of the resulting solid was obtained by weighing. A portion of this solid was added to excess 1M hydrochloric acid and stirred thoroughly. After no bubbles were generated, the solid was centrifuged to obtain a precipitate. The precipitate was washed with deionized water until the pH of the washing solution reached 7, and then vacuum dried. The content of non-acid-etchable inorganic rigid particles was obtained by weighing the precipitate. The content of acid-etchable inorganic rigid particles was obtained by subtracting the content of non-acid-etchable inorganic rigid particles from the total content of inorganic rigid particles. The multi-peak particle size of the inorganic rigid particles was measured using a Malvern Panalytical Mastersizer laser particle size analyzer with water or ethanol as the dispersed phase.

[0049] Table 2 shows the component amounts (parts by weight) in the examples and comparative examples.

[0050]

[0051] Performance testing

[0052] The biodegradable polyester compositions prepared in Examples 1-6 and Comparative Examples 1-5 were subjected to relevant performance tests. The test methods and standards are as follows, and the experimental results are shown in Table 3.

[0053] (1) Thickness and apparent density

[0054] A biodegradable polyester composition was made into a film of 20±2μm on a single-screw blown film machine with a screw diameter of 45cm and an aspect ratio of 20:1. The same apparent thickness was controlled using a thickness caliper. The average apparent thickness was tested according to ISO 4593:1993 standard, and the weight in grams and apparent density were calculated.

[0055] (2) Mechanical properties of membrane materials

[0056] Tensile strength and elongation at break are tested according to ISO 527-3:2018, tear strength is tested according to ISO 6383-2:2004, and dart impact strength is tested according to ISO 7765-1:1998.

[0057] Table 3 Performance Test Results

[0058]

[0059] As can be seen from the experimental data in Table 3, the films prepared by the biodegradable polyester compositions of the present invention, at similar thicknesses, can effectively balance mechanical properties and apparent density, achieving low apparent density while maintaining good mechanical properties, thereby reducing material costs. Specifically, the apparent density can be maintained between 0.891 and 0.989 g·cm³. -3 The longitudinal tensile strength can be maintained within the range of 19–20 MPa, the transverse tensile strength can be maintained within the range of 10–13 MPa, the longitudinal tear strength can be maintained within the range of 1862–1937 mN, the transverse tear strength can be maintained within the range of 2103–2460 mN, and the drop impact strength can be maintained within the range of 188–205 g.

[0060] The proportions of acid-etchable and non-acid-etchable inorganic rigid particles added in Comparative Examples 1-3 were unsuitable, resulting in mechanical properties such as tensile strength, tear strength, and impact strength that were inferior to those of the Example. Comparative Example 4 added only a single type of acid-etchable inorganic rigid particle, resulting in a higher apparent density. Comparative Example 5 added only a single type of non-acid-etchable inorganic rigid particle, resulting in a lower apparent density, but its mechanical properties such as tensile strength, tear strength, and impact strength were all poor, significantly inferior to those of the Example. This demonstrates that only through the combined action of acid-etchable and non-acid-etchable inorganic rigid particles can good mechanical properties be achieved while maintaining a low apparent density, which is beneficial for reducing material costs in the final product.

[0061] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A biodegradable polyester composition, characterized in that, Includes the following components by weight percentage: i. 75 to 100% by weight of biodegradable copolyester, based on the total weight of components i to ii; ii. 0 to 25% by weight of polylactic acid, based on the total weight of components i to ii; iii. 15–30% by weight of acid-etchable inorganic rigid particles, based on the total weight of components i–iv; iv. 1–15% by weight of non-acid-etchable inorganic rigid particles, based on the total weight of components i–iv; The mixed particle size of the acid-etchable and non-acid-etchable inorganic rigid particles conforms to the following distribution: D90 < 12 μm, D95 = 15 ~ 25 μm; the mixed particle size of the acid-etchable and non-acid-etchable inorganic rigid particles is a multi-peak particle size, which is confirmed by taking a certain amount of biodegradable polyester composition, placing it in a covered crucible, calcining it in a muffle furnace at 500℃ to constant weight, and testing the ash content with water or ethanol as the dispersed phase on a Malvern Panalytical Mastersizer laser particle size analyzer.

2. The biodegradable polyester composition according to claim 1, characterized in that, Includes the following components by weight percentage: i. 90–95% by weight of biodegradable copolyester, based on the total weight of components i–ii; ii. 5 to 10% by weight of polylactic acid, based on the total weight of components i to ii; iii. 21–24% by weight of acid-etchable inorganic rigid particles, based on the total weight of components i–iv; iv. 5–8% by weight of non-acid-etchable inorganic rigid particles, based on the total weight of components i–iv.

3. The biodegradable polyester composition according to claim 1 or 2, characterized in that, The biodegradable copolyester is a copolymer based on aliphatic and / or aromatic dicarboxylic acids and based on aliphatic dihydroxy compounds.

4. The biodegradable polyester composition according to claim 1, characterized in that, The biodegradable copolyester includes at least one of a copolymer of butylene adipate and butylene terephthalate, and a copolymer of butylene sebacate and butylene terephthalate.

5. The biodegradable polyester composition according to claim 1, characterized in that, Includes the following two items: (1) and (2): (1) The acid-etchable inorganic rigid particles are at least one of calcium carbonate and calcite; (2) The non-acid-etchable inorganic rigid particles include at least one of talc, silicon dioxide, barium sulfate, and titanium dioxide.

6. The biodegradable polyester composition according to claim 1, characterized in that, The biodegradable polyester composition further includes an opening agent comprising 0 to 0.5% of the total weight of components i to iv.

7. A method for preparing a biodegradable polyester composition according to any one of claims 1 to 6, characterized in that, Includes the following steps: First, biodegradable copolyester and polylactic acid are uniformly mixed and dried. Then, they are stirred and mixed with acid-etchable inorganic rigid particles, non-acid-etchable inorganic rigid particles, and an opening agent. The resulting uniform mixture is melt-plasticized, extruded, and granulated to obtain a biodegradable polyester composition.

8. The preparation method according to claim 7, characterized in that, It includes at least the following (1) and (2). One of the following: (1) The drying temperature is 70-90℃ and the drying time is 4-6h; (2) The mixing time is 1 to 5 minutes.

9. The preparation method according to claim 7, characterized in that, The set temperature for melt plasticizing, extrusion, and granulation is 60–190℃, the rotation speed is 250–320 rpm, and the extrusion speed is 550–630 kg / h.

10. The use of a biodegradable polyester composition as described in any one of claims 1 to 6 in the preparation of a biodegradable film product.

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