Biodegradable composition, and preparation method and use therefor

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

[0001] The present application belongs to the technical field of polymer materials, and specifically relates to a biodegradable composition, a preparation method and an application thereof. Background Art

[0002] Compared with traditional polyethylene (PE), biodegradable flexible biodegradable polyester + PLA-MD materials often experience perforation and air leakage during the blown film production process, seriously affecting production stability. In the event of perforation and air leakage, the only way is to stop the machine, clean it, and then pull the film bubble production. This constant shutdown and cleaning greatly affects production efficiency and causes waste of material and labor costs. In the traditional PE blown film industry, the current solution to perforation and air leakage is to increase the die gap, but this makes the film thickness difficult to control. Another solution is to add fluorine-containing processing aids. Fluorine-containing processing aids not only cause great pollution to the environment, but are also carcinogenic and are not allowed in the field of biodegradable materials.

[0003] Patent CN 115716958 A describes how the synergistic effect of internal lubricants polyethylene wax, zinc stearate, and PPA can extend die cleaning cycles and mitigate perforation leakage. However, the zinc stearate in this patent is generally believed to be detrimental to biodegradable polyesters, potentially causing aging and rapid degradation of mechanical properties, hindering their application. Furthermore, the polyethylene wax and polyamide-polyether-polyamide (PPA) used in the patent are non-biodegradable substances, and excessive levels can easily render the product unsuitable for industrial composting. Summary of the Invention

[0004] 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 require the use of fluorine-containing organic compounds.

[0005] 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;

[0006] The high-frequency 100 Hz composite viscosity of the biodegradable polyester is 50-500 Pa·S;

[0007] 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.

[0008] In some embodiments, the composition comprises 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.

[0009] In some embodiments, the composition comprises at least one feature selected from the group consisting of (1) to (5):

[0010] (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;

[0011] (2) The biodegradable polyester is selected from aliphatic copolyesters and / or aliphatic-aromatic copolyesters;

[0012] (3) The polylactic acid is selected from at least one of left-handed polylactic acid (PLLA), right-handed polylactic acid (PDLA), and a PLLA / PDLA copolymer;

[0013] (4) the polylactic acid has a melt flow rate of 1-20 g / 10 min at 190° C. and a load of 2.16 kg;

[0014] (5) The glass transition temperature of the polylactic acid is 40 to 60°C.

[0015] In some embodiments, the composition comprises at least one feature selected from the group consisting of (1) to (2):

[0016] (1) The inorganic filler is at least one of calcium carbonate and talc;

[0017] (2) The chain extender includes at least one of an epoxy reactive chain extender and an isocyanate chain extender.

[0018] In some embodiments, the inorganic filler has a D50 particle size of ≤6 μm.

[0019] 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.

[0020] The present application also provides a method for preparing the biodegradable composition, comprising the following steps:

[0021] Premixing a chain extender, polylactic acid, an optional auxiliary agent, and a portion of biodegradable polyester to obtain a premix;

[0022] The premix and the remaining biodegradable polyester are fed as main materials and inorganic fillers are fed as side materials, melt-extruded into granules, cooled, air-dried, granulated, dried and homogenized to prepare the biodegradable composition.

[0023] In some embodiments, the preparation method includes at least one feature selected from the following (1) to (3):

[0024] (1) The partially biodegradable polyester accounts for 10 to 75% of the total mass of the biodegradable polyester;

[0025] (2) The rotation speed of the premix is ​​240-400 rpm;

[0026] (3) The temperature of the melt extrusion granulation is 150-200°C.

[0027] The present application also provides a food packaging film / bag, which is prepared from raw materials including the biodegradable composition.

[0028] The present application also provides an application of the biodegradable composition in the field of catering bags.

[0029] Compared with the prior art, this application has the following beneficial effects:

[0030] (1) The biodegradable composition of the present application can effectively control the occurrence of perforation and air leakage, with a small number of perforation and air 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 are not used, which is safer and more environmentally friendly.

[0031] (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

[0032] The present application adopts the following technical solution: 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;

[0033] The high-frequency 100 Hz composite viscosity of the biodegradable polyester is 50-500 Pa·S;

[0034] 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 melt flow rate is tested according to ISO-1133.

[0035] In some embodiments, the present invention provides a method for testing the high-frequency 100 Hz complex viscosity number: a sample is loaded into a rotational rheometer and equilibrated at 150°C for 5 minutes; a strain sweep experiment is then performed with a strain of 1.0% and a shear rate ranging from 0.01 Hz to 100 Hz, and the complex viscosity is read at 100 Hz. In some embodiments, the rotational rheometer is a Discovery HR-2 (TA Instruments).

[0036] 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.

[0037] In some embodiments, the biodegradable polyester has a high-frequency 100 Hz composite viscosity of 100-400 Pa·S.

[0038] 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.

[0039] In some embodiments, the biodegradable polyester is selected from aliphatic copolyesters and / or aliphatic-aromatic copolyesters.

[0040] In some embodiments, the biodegradable polyester is selected from one or a combination of aliphatic-aromatic copolyesters.

[0041] In some embodiments, the T content of the aliphatic-aromatic copolyester is 40-60%.

[0042] The T content of the biodegradable polyester described herein is the molar ratio of terephthalic acid units (PTA) to the total dibasic acid units of the biodegradable polyester.

[0043] In some embodiments, the aliphatic-aromatic copolyester may be selected from one or a combination of polybutylene adipate terephthalate (PBAT), polybutylene sebacate terephthalate (PBSeT).

[0044] 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 vacuum, and reacting for 2-5 hours to obtain the aliphatic-aromatic copolyester.

[0045] The source of the aliphatic-aromatic copolyester described in this application is not limited to the above-mentioned preparation method, and can also be derived from commercially available products.

[0046] 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).

[0047] In some embodiments, in the biodegradable composition, the content of the biodegradable polyester is not less than 35 wt %.

[0048] In some embodiments, the polylactic acid is selected from at least one of PLLA, PDLA, and PLLA / PDLA copolymer.

[0049] In some embodiments, the polylactic acid has a melt flow rate of 1-20 g / 10 min at 190° C. and a load of 2.16 kg. The melt flow rate test method refers to ISO-1133 standard.

[0050] 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.

[0051] In some embodiments, the glass transition temperature of the polylactic acid is 40 to 60°C.

[0052] In some embodiments, the inorganic filler is at least one of calcium carbonate and talc.

[0053] In some embodiments, the inorganic filler is calcium carbonate modified or unmodified with a surfactant.

[0054] In some embodiments, the method for preparing the surfactant-modified calcium carbonate is as follows: placing native calcium carbonate into 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.

[0055] In some embodiments, the chain extender includes at least one of an epoxy reactive chain extender and an isocyanate chain extender.

[0056] 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.

[0057] In some embodiments, the inorganic filler has a D50 particle size of ≤6 μm. The D50 particle size is measured according to the method in GB / T 19077.1 "Particle Size Analysis - Laser Diffraction Method".

[0058] In some embodiments, the inorganic filler has a D50 particle size of ≤5 μm.

[0059] In some embodiments, the raw materials for preparing the biodegradable composition further include 0.1-2 parts of an auxiliary agent.

[0060] In some embodiments, the auxiliary agent includes at least one of an opening agent and a lubricant.

[0061] In some embodiments, the anti-blocking agent includes at least one of talc, silicon dioxide, and PE wax.

[0062] In some embodiments, the lubricant includes at least one of erucamide, oleamide, monostearate glyceric acid, pentaerythritol stearate, PE wax, and ethylene bisstearamide EBS.

[0063] In some embodiments, the biodegradable composition has a perforation leakage frequency of ≤3 times and a heat sealing strength of ≥6 MPa.

[0064] 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, feeding the inorganic filler as the side feed, melt-extruding and granulating, cooling, air-drying, pelletizing, drying, and homogenizing to obtain the biodegradable composition.

[0065] In some embodiments, the partially biodegradable polyester accounts for 10 to 75% of the total mass of the biodegradable polyester.

[0066] In some embodiments, the premixing speed is 240-400 rpm.

[0067] In some embodiments, the temperature of the melt extrusion granulation is 150-200°C.

[0068] It is understood that the present application also discloses a raw material composition for preparing the biodegradable composition described in any of the above embodiments.

[0069] 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 embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0070] In the following examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified. Unless otherwise specified, the opener is commercially available, and the same opener is used in parallel experiments.

[0071] The raw materials used in the examples and comparative examples are shown in Table 1.

[0072] Table 1

[0073] Examples 1 to 17 and Comparative Examples 1 to 6

[0074] 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.

[0075] The preparation method of the biodegradable composition of Examples 1 to 17 and Comparative Examples 1 to 6 comprises the following steps:

[0076] The biodegradable composition is prepared by premixing an additive, a chain extender, polylactic acid, and a portion of the biodegradable polyester to obtain a premix. The premix is ​​then fed with the remaining biodegradable polyester as a main feed and an inorganic filler as a side feed, melt-extruded into pellets, cooled, air-dried, pelletized, dried, and homogenized. The portion of the biodegradable polyester accounts for 50% of the total mass of the biodegradable polyester. The premixing speed is 300 rpm, and the melt-extrusion pelletizing temperature is 150-200°C.

[0077] Table 2 Component dosage (parts by weight)

[0078] Table 3 Component dosage (parts by weight)

[0079] Table 4 Comparative Examples Component Amounts (parts by weight)

[0080] Performance Testing

[0081] The biodegradable compositions prepared in the examples and comparative examples were subjected to perforation air leakage and heat seal strength tests.

[0082] Perforation and air leakage test method: Use a 45mm single-screw film blowing machine with a die gap of 1.8mm, a die diameter of 70mm, a blow-up ratio of 3.0, a set temperature of 150°C, a film blowing frequency of 30Hz, and a film thickness of 20μm. Blow the film continuously for 10 hours and observe the number of perforations and air leakages. Pause the time when perforations and air leakage occur, and continue timing after the film is stabilized after re-drawing. The minimum requirement is ≤3 times / 10 hours.

[0083] Heat seal strength test is carried out in accordance with GB / T 2358-1998 standard. The requirement is ≥6MPa.

[0084] The test results are shown in Table 5.

[0085] Table 5 Performance test results

[0086] 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 / 10 hours, and the heat sealing strength of the film bag prepared is ≥6 MPa, which can be achieved in the range of 6.1 to 10.6 MPa.

[0087] The biodegradable polyesters used in Comparative Examples 1-2 had inappropriate composite viscosity numbers, the biodegradable polyesters used in Comparative Example 3 had inappropriate melt flow rates, and the biodegradable polyesters used in Comparative Example 4 had inappropriate composite viscosity numbers and melt flow rates. Consequently, the resulting biodegradable compositions exhibited significantly poorer resistance to perforation and air leakage, and the resulting film bag heat seal strength was inferior to that of the Examples. Comparative Example 5 did not contain polylactic acid, resulting in the resulting biodegradable compositions exhibiting lower heat seal strength and significantly poorer resistance to perforation and air leakage. Comparative Example 6 did not contain a chain extender, resulting in the resulting biodegradable compositions exhibiting significantly poorer resistance to perforation and air leakage, and the resulting film bag heat seal strength was also poor. Furthermore, due to poor compatibility, the different components separated at the die opening and precipitated at the die opening.

[0088] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed in this application shall be covered by the claims of this application.

Claims

1. A biodegradable composition, It is 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.

2. The biodegradable composition according to claim 1, It is characterized in that The raw materials for preparing the composite material 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.

3. The biodegradable composition according to claim 1, It is characterized in that Including 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.

4. The biodegradable composition according to claim 1, It is characterized in that Including 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.

5. The biodegradable composition according to claim 4, It is characterized in that The D50 particle size of the inorganic filler is ≤6 μm.

6. The biodegradable composition according to claim 1, It is characterized in that The biodegradable composition further comprises the following components in parts by weight: 0.1-2 parts of auxiliary agent.

7. A method for preparing the biodegradable composition according to any one of claims 1 to 6, It is characterized in that The following steps are involved: 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.

8. The preparation method according to claim 7, It is characterized in that Including 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.

9. A food packaging film / bag, It is characterized in that The biodegradable composition is prepared from raw materials comprising any one of claims 1 to 6.

10. Use of the biodegradable composition according to any one of claims 1 to 6 in the field of catering bags.

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