WO2025113689A1 - Biodegradable composition, and preparation method and use therefor - Google Patents

Abstract

The application relates to a biodegradable composition, and a preparation method and use therefor. The biodegradable composition is prepared from the following raw materials in parts by weight: 40-91 parts of a biodegradable polyester, 2-20 parts of polylactic acid, 7-40 parts of an inorganic filler, and 0.1-0.8 part of a chain extender. The high-frequency 100 Hz composite viscosity of the biodegradable polyester is 50-500 Pa·S. The melt flow rate of the biodegradable polyester under test conditions of 190 C° and 2.16 kg is 2-10 g/10 min. The biodegradable composition of the present application can effectively control the occurrence of perforation air leakage, the heat-sealing strength of a prepared film bag is larger than or equal to 6MPa, and fluorine-containing organic compounds are not used.

Description

A biodegradable composition and its preparation method and application Technical Field

The present application belongs to the technical field of polymer materials, and specifically relates to a biodegradable composition and a preparation method and application thereof.

Background Art

Compared with traditional polyethylene (PE), biodegradable flexible biodegradable polyester + PLA-MD materials often have perforations and air leakage during the film blowing production process, which seriously affects the stability of production. In case of perforation and air leakage, the only way is to stop the machine to clean it again and then pull the film bubble production. Such continuous shutdown and cleaning greatly affects the production efficiency and causes waste of materials and labor costs. In the traditional PE blown film industry, the current solution to perforation and air leakage is to increase the gap between the die and the mouth, but this will make the thickness of the film difficult to control. There is also a method of adding fluorine-containing processing aids to solve it. Fluorine-containing processing aids first cause great pollution to the environment, and are also carcinogenic, which is not allowed in the field of biodegradable materials.

Patent CN 115716958 A describes that through the synergistic effect of internal lubricant polyethylene wax and zinc stearate and PPA, the die cleaning cycle can be extended and perforation leakage can be alleviated. However, the zinc stearate in this patent is generally believed to have a destructive effect on biodegradable polyester, which can easily cause the aging performance of biodegradable materials, causing the mechanical properties to decay rapidly, affecting their application. In addition, the polyethylene wax polyamide-polyether-polyamide (PPA) used in the patent are non-biodegradable substances, and too high a content can easily lead to products that cannot meet industrial composting degradation requirements.

Summary of the invention

The present application provides a biodegradable composition and its preparation method and application. The biodegradable composition of the present application can effectively control the occurrence of perforation and air leakage, and the film bag prepared has high heat sealing strength (for example, ≥6MPa), and does not need to use fluorine-containing organic compounds.

The present application provides a biodegradable composition, the raw materials for its preparation include the following components in parts by weight: 40-91 parts of biodegradable polyester, 2-20 parts of polylactic acid, 7-40 parts of inorganic filler, and 0.1-0.8 parts of chain extender;

The high-frequency 100 Hz composite viscosity of the biodegradable polyester is 50-500 Pa·S;

The biodegradable polyester has a melt flow rate of 2 to 10 g/10 min at 190° C. and a load of 2.16 kg.

In some embodiments, the composition includes the following components in parts by weight: 55-90 parts of biodegradable polyester, 3-12 parts of polylactic acid, 7-33 parts of inorganic filler, and 0.2-0.6 parts of chain extender.

In some embodiments, the composition comprises at least one feature selected from the following (1) to (5):

(1) The biodegradable polyester has a melt flow rate of 3.5 to 8 g/10 min at 190° C. and a load of 2.16 kg;

(2) the biodegradable polyester is selected from aliphatic copolyesters and/or aliphatic-aromatic copolyesters;

(3) The polylactic acid is selected from at least one of left-handed polylactic acid (PLLA), right-handed polylactic acid (PDLA), and PLLA/PDLA copolymer;

(4) The melt flow rate of the polylactic acid at 190° C. and 2.16 kg load is 1-20 g/10 min;

(5) The glass transition temperature of the polylactic acid is 40 to 60°C.

In some embodiments, the composition comprises at least one feature selected from the following (1) to (2):

(1) The inorganic filler is at least one of calcium carbonate and talc;

(2) The chain extender includes at least one of an epoxy reactive chain extender and an isocyanate chain extender.

In some embodiments, the D50 particle size of the inorganic filler is ≤6 μm.

In some embodiments, the raw materials for preparing the biodegradable composition further include the following components in parts by weight: 0.1-2 parts of auxiliary agent.

The present application also provides a method for preparing the biodegradable composition, comprising the following steps:

Premixing a chain extender, polylactic acid, an optional auxiliary agent, and a portion of biodegradable polyester to obtain a premix;

The premix and the remaining biodegradable polyester are mainly fed, the inorganic filler is side-fed, melt-extruded and granulated, cooled, air-dried, granulated, dried and homogenized to obtain the biodegradable composition.

In some embodiments, the preparation method includes at least one feature selected from the following (1) to (3):

(1) The partially biodegradable polyester accounts for 10 to 75% of the total mass of the biodegradable polyester;

(2) The rotation speed of the premix is 240-400 rpm;

(3) The temperature of the melt extrusion granulation is 150-200°C.

The present application also provides a food packaging film/bag, which is prepared from raw materials including the biodegradable composition.

The present application also provides an application of the biodegradable composition in the field of catering bags.

Compared with the prior art, this application has the following beneficial effects:

(1) The biodegradable composition of the present application can effectively control the occurrence of perforation and leakage, with a small number of perforation and leakage (for example, ≤3 times), and the film bag prepared has a high heat sealing strength (for example, ≥6MPa). At the same time, fluorine-containing organic compounds do not need to be used, which is safer and more environmentally friendly.

(2) The components used in this application are commonly used substances in the field of biodegradable material modification. The synergistic effect of different components is used to optimize the perforation leakage phenomenon, which is a feasible solution more suitable for the biodegradation field and will not affect the aging performance and industrial composting performance.

DETAILED DESCRIPTION

The present application adopts the following technical scheme: a biodegradable composition, the raw materials for its preparation include the following components in parts by weight: 40-91 parts of biodegradable polyester, 2-20 parts of polylactic acid, 7-40 parts of inorganic filler, and 0.1-0.8 parts of chain extender;

The high-frequency 100 Hz composite viscosity of the biodegradable polyester is 50-500 Pa·S;

The biodegradable polyester has a melt flow rate of 2 to 10 g/10 min at 190° C. and a load of 2.16 kg. The test method of the melt flow rate refers to ISO-1133 standard.

In some embodiments, the test method of the high-frequency 100Hz composite viscosity number of the present application is as follows: the sample is loaded into a rotational rheometer and balanced at 150°C for 5 minutes; then a strain sweep experiment is performed with a strain of 1.0%, and a strain sweep test is performed at a shear rate from 0.01Hz to 100Hz, and the composite viscosity at 100Hz is read. In some embodiments, the rotational rheometer is a Discovery HR-2, TA instruments.

In some embodiments, the raw materials for preparing the biodegradable composition include the following components in parts by weight: 55-90 parts of biodegradable polyester, 3-12 parts of polylactic acid, 7-33 parts of inorganic filler, and 0.2-0.6 parts of chain extender.

In some embodiments, the high-frequency 100 Hz composite viscosity of the biodegradable polyester is 100-400 Pa·S.

In some embodiments, the biodegradable polyester has a melt flow rate of 3.5-8 g/10 min at 190° C. and a load of 2.16 kg.

In some embodiments, the biodegradable polyester is selected from aliphatic copolyesters and/or aliphatic-aromatic copolyesters.

In some embodiments, the biodegradable polyester is selected from one or a combination of aliphatic-aromatic copolyesters.

In some embodiments, the aliphatic-aromatic copolyester has a T content of 40-60%.

The T content of the biodegradable polyester described in the present application is the molar ratio of terephthalic acid units (PTA) to the total dibasic acid units of the biodegradable polyester.

In some embodiments, the aliphatic-aromatic copolyester may be selected from one or a combination of polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT).

In some embodiments, the preparation method of the aliphatic-aromatic copolyester comprises the following steps: adding terephthalic acid, adipic acid and excess 1,4-butanediol and glycerol, stirring at 150-200° C. for 1-5 hours, then adding tetrabutyl titanate, heating to 220-250° C., opening the vacuum, and reacting for 2-5 hours to obtain the aliphatic-aromatic copolyester.

The source of the aliphatic-aromatic copolyester described in the present application is not limited to the above-mentioned preparation method, and can also be derived from commercially available products.

In some embodiments, the aliphatic copolyester may be selected from at least one of conventional aliphatic polyesters in the art such as polybutylene succinate-adipate resin (PBSA).

In some embodiments, in the biodegradable composition, the content of the biodegradable polyester is not less than 35 wt %.

In some embodiments, the polylactic acid is selected from at least one of PLLA, PDLA, and PLLA/PDLA copolymer.

In some embodiments, the melt flow rate of the polylactic acid at 190° C. and a load of 2.16 kg is 1-20 g/10 min. The test method of the melt flow rate refers to ISO-1133 standard.

In some embodiments, the polylactic acid has a melt flow rate of 4-15 g/10 min at 190° C. and a load of 2.16 kg.

In some embodiments, the glass transition temperature of the polylactic acid is 40 to 60°C.

In some embodiments, the inorganic filler is at least one of calcium carbonate and talc.

In some embodiments, the inorganic filler is calcium carbonate modified or unmodified by a surfactant.

In some embodiments, the method for preparing the surfactant-modified calcium carbonate is: placing native calcium carbonate in a high-speed mixer, adding a surfactant, setting the high-speed mixer speed to 40 Hz, mixing for 5-10 minutes, and mixing to obtain the surfactant-modified calcium carbonate.

In some embodiments, the chain extender includes at least one of an epoxy reactive chain extender and an isocyanate chain extender.

In some embodiments, the epoxy reactive chain extender can be selected from acrylic acid and styrene copolymer ADR 4370 (BASF) containing epoxy functional groups, etc.; and/or the isocyanate chain extender can be selected from diphenylmethane diisocyanate MDI, toluene diisocyanate TDI, etc.

In some embodiments, the D50 particle size of the inorganic filler is ≤6 μm. The D50 particle size is tested in accordance with GB/T19077.1 "Particle Size Analysis by Laser Diffraction Method".

In some embodiments, the D50 particle size of the inorganic filler is ≤5 μm.

In some embodiments, the raw materials for preparing the biodegradable composition further include 0.1-2 parts of auxiliary agents.

In some embodiments, the auxiliary agent includes at least one of an opening agent and a lubricant.

In some embodiments, the anti-blocking agent includes at least one of talc, silicon dioxide, and PE wax.

In some embodiments, the lubricant includes at least one of erucamide, oleamide, monostearate glycerol, pentaerythritol stearate, PE wax, and ethylene bisstearamide EBS.

In some embodiments, the biodegradable composition has a perforation leakage frequency of ≤3 times and a heat sealing strength of ≥6 MPa.

The present application also claims protection for a method for preparing the biodegradable composition, comprising the following steps: premixing a chain extender, polylactic acid, and an optional auxiliary agent ("optional" means that when the auxiliary agent is included, the auxiliary agent is premixed with the chain extender, polylactic acid and a portion of the biodegradable polyester; when the auxiliary agent is not included, the chain extender, polylactic acid and a portion of the biodegradable polyester are premixed), and a portion of the biodegradable polyester to obtain a premix, feeding the premix and the remaining biodegradable polyester as the main feed, and feeding the inorganic filler as the side feed, melt-extruding and granulating, cooling, air-drying, pelletizing, drying, and homogenizing to obtain the biodegradable composition.

In some embodiments, the partially biodegradable polyester accounts for 10 to 75% of the total mass of the biodegradable polyester.

In some embodiments, the premixing speed is 240-400 rpm.

In some embodiments, the temperature of the melt extrusion granulation is 150-200°C.

It is to be understood that the present application also discloses a raw material composition for preparing the biodegradable composition described in any of the above embodiments.

The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

In the following examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified. Unless otherwise specified, the opening agent is commercially available, and the same opening agent is used in parallel experiments.

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

Table 1

Examples 1 to 17 and Comparative Examples 1 to 6

The components and weight proportions of the biodegradable compositions of Examples 1 to 17 and Comparative Examples 1 to 6 are shown in Tables 2 to 4.

The preparation method of the biodegradable composition of Examples 1 to 17 and Comparative Examples 1 to 6 comprises the following steps:

The auxiliary agent, chain extender, polylactic acid and part of the biodegradable polyester are premixed to obtain a premix, the premix and the remaining biodegradable polyester are mainly fed, the inorganic filler is side fed, melt extruded and granulated, cooled, air-dried, granulated, dried and homogenized to obtain the biodegradable composition, wherein the part of the biodegradable polyester is 50% of the total mass of the biodegradable polyester; the premixing speed is 300 rpm; the melt extrusion granulation temperature is 150-200°C.

Table 2 Component dosage (parts by weight)

Table 3 Component dosage (parts by weight)

Table 4 Component dosage in comparative example (parts by weight)

Performance Testing

The biodegradable compositions prepared in the examples and comparative examples were subjected to perforation air leakage and heat sealing strength tests.

Perforation and air leakage test method: Use a 45 single-screw film blowing machine, a die with a die gap of 1.8mm, a die diameter of 70mm, a blow-up ratio of 3.0, a set temperature of 150℃, a film blowing frequency of 30Hz, a film thickness of 20μm, and blow film continuously for 10 hours. Observe the number of perforations and air leakages, pause the time when perforations and air leakage occur, and continue timing after the film is re-pulled and stabilized. The minimum requirement is ≤3 times/10 hours.

Heat seal strength test is carried out according to GB/T 2358-1998 standard. Requirement: ≥6MPa.

The test results are shown in Table 5.

Table 5 Performance test results

From the data in Table 4, it can be seen that the biodegradable composition prepared in the embodiment of the present application can effectively control the occurrence of perforation and leakage, the number of perforation and leakage can be controlled within 3 times/10h, and the heat sealing strength of the prepared film bag is ≥6MPa, which can be achieved in the range of 6.1 to 10.6MPa.

The composite viscosity of the biodegradable polyester selected in Comparative Examples 1-2 is not appropriate, the melt flow rate of the biodegradable polyester selected in Comparative Example 3 is not appropriate, and the composite viscosity and melt flow rate of the biodegradable polyester selected in Comparative Example 4 are not appropriate, resulting in a significant deterioration in the resistance to perforation and air leakage of the final biodegradable composition, and the heat sealing strength of the film bag is also worse than that of the embodiment. Comparative Example 5 does not contain polylactic acid, resulting in a low heat sealing strength of the final biodegradable composition, and a significant deterioration in the resistance to perforation and air leakage. Comparative Example 6 does not contain a chain extender, resulting in a significant deterioration in the resistance to perforation and air leakage of the final biodegradable composition, and the heat sealing strength of the film bag is also poor, and due to poor compatibility, different components will be separated at the die and precipitated at the die.

The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims (10)

A biodegradable composition, characterized in that the raw materials for its preparation include the following components in parts by weight: 40-91 parts of biodegradable polyester, 2-20 parts of polylactic acid, 7-40 parts of inorganic filler, and 0.1-0.8 parts of chain extender; The high-frequency 100 Hz composite viscosity of the biodegradable polyester is 50-500 Pa·S; The biodegradable polyester has a melt flow rate of 2 to 10 g/10 min at 190° C. and a load of 2.16 kg. The biodegradable composition according to claim 1, characterized in that the raw materials for its preparation include the following components in parts by weight: 55-90 parts of biodegradable polyester, 3-12 parts of polylactic acid, 7-33 parts of inorganic filler, and 0.2-0.6 parts of chain extender. The biodegradable composition according to claim 1, characterized in that it comprises at least one selected from the following (1) to (5): (1) The biodegradable polyester has a melt flow rate of 3.5 to 8 g/10 min at 190° C. and a load of 2.16 kg; (2) the biodegradable polyester is selected from aliphatic copolyesters and/or aliphatic-aromatic copolyesters; (3) The polylactic acid is selected from at least one of left-handed polylactic acid (PLLA), right-handed polylactic acid (PDLA), and PLLA/PDLA copolymer; (4) The melt flow rate of the polylactic acid at 190° C. and 2.16 kg load is 1-20 g/10 min; (5) The glass transition temperature of the polylactic acid is 40 to 60°C. The biodegradable composition according to claim 1, characterized in that it comprises at least one selected from the following (1) to (2): (1) The inorganic filler is at least one of calcium carbonate and talc; (2) The chain extender includes at least one of an epoxy reactive chain extender and an isocyanate chain extender. The biodegradable composition according to claim 4, characterized in that the D50 particle size of the inorganic filler is ≤6 μm. The biodegradable composition according to claim 1, characterized in that the biodegradable composition further comprises the following components in parts by weight: 0.1-2 parts of an auxiliary agent. A method for preparing a biodegradable composition according to any one of claims 1 to 6, characterized in that it comprises the following steps: Premixing a chain extender, polylactic acid, an optional auxiliary agent, and a portion of biodegradable polyester to obtain a premix; The premix and the remaining biodegradable polyester are mainly fed, the inorganic filler is side-fed, melt-extruded and granulated, cooled, air-dried, granulated, dried and homogenized to obtain the biodegradable composition. The preparation method according to claim 7, characterized in that it comprises at least one selected from the following (1) to (3): (1) The partially biodegradable polyester accounts for 10 to 75% of the total mass of the biodegradable polyester; (2) The rotation speed of the premix is 240-400 rpm; (3) The temperature of the melt extrusion granulation is 150-200°C. A food packaging film/bag, characterized in that it is made from raw materials comprising the biodegradable composition according to any one of claims 1 to 6. A use of the biodegradable composition according to any one of claims 1 to 6 in the field of catering bags.