Low-temperature embrittlement-resistant mulching film as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer materials, and provides a low-temperature embrittlement-resistant mulching film as well as a preparation method and application thereof. The low-temperature embrittlement-resistant mulching film is prepared from the following raw material components: PLA, PBAT, PE and a compatibilizer, the compatibilizer is prepared from PLA-PEG-NH2 (Polylactic Acid-Polyethylene Glycol) and polyolefin grafted maleic anhydride. According to the technical scheme, the problem that the mulching film is easy to crack at low temperature due to incompatibility of PE and polar PBAT and PLA blending materials in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a low-temperature anti-brittle cracking ground film, a preparation method thereof, and applications thereof. Background Art

[0002] Ground film is a polymer compound, a plastic film promoted by the government for agricultural use. It increases warmth, retains moisture, and promotes crop growth. Traditionally, polyethylene (PE) has been the most common material used in ground film. With technological advancements, polylactic acid (PLA) is increasingly being used in ground film production, replacing traditional PE.

[0003] Polylactic acid, also known as polylactide, is chemically synthesized using lactic acid, a product of microbial fermentation, as its monomer. It has the advantage of being self-degradable after use, preventing environmental pollution, and to some extent, addresses the environmental impact of polyethylene mulch. However, PLA suffers from poor impact and tear resistance. To address this issue, PBAT is used to toughen PLA. Blends of PBAT and PLA, used as mulch materials, combine the plasticity, heat resistance, and physical processing properties of PLA with the tensile strength and flexibility of PBAT.

[0004] Ground films used in greenhouses over the winter must exhibit excellent low-temperature resistance and resist breaking or cracking at low temperatures. However, PBAT and PLA blends, when used as ground films, have poor low-temperature resistance. To improve this resistance, PE, which also has good low-temperature resistance, can be added to the blend. However, both PBAT and PLA contain numerous ester groups, making them polar polymers, while PE, a highly non-polar hydrocarbon polymer, is incompatible with the polar PBAT and PLA blends. Consequently, the addition of PE has a very limited effect on improving the low-temperature resistance of the PBAT and PLA blend. Summary of the Invention

[0005] The present invention provides a low-temperature brittle crack-resistant ground film, a preparation method thereof, and an application thereof, which solves the problem of incompatibility between PE and polar PBAT and PLA blends in the related art.

[0006] The technical solutions of the present invention are as follows: A low-temperature anti-brittle cracking ground film, the raw materials of which include the following components: PLA, PBAT, PE and a compatibilizer; the compatibilizer includes PLA-PEG-NH2 and polyolefin grafted maleic anhydride.

[0007] In the present invention, PLA-PEG-NH2 is polylactic acid-polyethylene glycol-amino.

[0008] In the present invention, PLA can be any conventional PLA material in the art, for example, PLA Hisun Biotech REVODE190, PLA Thailand Total LX175, PLA Fengyuan Chemical FY802, PLA Anhui Fengyuan FY602, etc., preferably PLA Hisun Biotech REVODE190.

[0009] In the present invention, PBAT can be any conventional PBAT material in the art, for example, PBAT Sinopec degradation material TA159, PBAT Zhejiang Huafeng HF101, PBAT Changchun ECO-A05, PBAT Changchun ECO-A20, PBAT Germany BASF C1200, etc., preferably PBAT Germany BASF C1200.

[0010] In the present invention, PE can be any conventional PE material in the art, for example, low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), preferably LLDPE, because it has good low-temperature resistance and can still maintain a certain toughness at low temperatures. Its impact resistance at low temperatures is much higher than that of LDPE. LLDPE Sinopec DFDA-7042 is more preferred.

[0011] In the present invention, the polyolefin grafted maleic anhydride can be any conventional polyolefin grafted maleic anhydride material in the art, for example, PE grafted maleic anhydride, PP grafted maleic anhydride, preferably PE grafted maleic anhydride, more preferably LLDPE grafted maleic anhydride, for example, LLDPE grafted maleic anhydride Dow 41E710.

[0012] In the present invention, the mass ratio of PLA, PBAT, PE and compatibilizer can be any conventional amount in the art, and the mass ratio is preferably 60:30~40:10~15:1~5, for example, it can be 60:30:10:5, 60:35:12:3, 60:40:15:1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0013] As a further technical solution, the compatibilizer further includes PBAT grafted with GMA.

[0014] In the present invention, the PBAT grafted GMA can be a conventional material with any grafting rate in the art. The addition of PBAT grafted GMA improves the overall compatibility of the base material in the ground film and further improves the low-temperature brittle crack resistance of the ground film.

[0015] As a further technical solution, the mass of the PLA-PEG-NH2 and PBAT grafted GMA is greater than or equal to the mass of the polyolefin grafted maleic anhydride.

[0016] In the present invention, the mass of PLA-PEG-NH2 and PBAT grafted GMA is further limited and ≥ the mass of polyolefin grafted maleic anhydride, which further improves the low-temperature brittle cracking resistance of the ground film.

[0017] As a further technical solution, the mass ratio of the PLA-PEG-NH2 and PBAT grafted GMA to the polyolefin grafted maleic anhydride is 3~4:1.

[0018] In the present invention, the mass ratio of PLA-PEG-NH2 and PBAT grafted GMA and the mass ratio of PLA-PEG-NH2 and PBAT grafted maleic anhydride to polyolefin grafted maleic anhydride are further limited to 3-4:1, which further improves the low-temperature brittle cracking resistance of the ground film.

[0019] As a further technical solution, the mass ratio of the PLA-PEG-NH2 and PBAT grafted GMA is 3~5:1.

[0020] As a further technical solution, the raw materials further include auxiliary agents; the auxiliary agents include one or more of antioxidants, fillers, and ultraviolet absorbers.

[0021] In the present invention, the raw materials of the ground film may further include auxiliary agents.

[0022] The auxiliary agent can be an antioxidant. Adding an antioxidant can delay or inhibit the oxidation reaction of the ground film due to the action of oxygen or ozone in the atmosphere during storage, transportation, processing and use, resulting in a significant reduction in performance properties such as impact strength, tensile strength, bending strength and elongation at break, thereby preventing aging of the ground film and extending its service life. The antioxidant can be antioxidant 1010, antioxidant 300, antioxidant 168, antioxidant 1076, antioxidant 264, antioxidant 3114, etc.

[0023] Additives can also be fillers. Adding fillers can improve the heat resistance, rigidity, hardness, dimensional stability, creep resistance, wear resistance, flame retardancy, smoke suppression and biodegradability of the ground film, reduce molding shrinkage and improve product precision. Fillers can be calcium carbonate, talc, kaolin, mica powder, barium sulfate, glass beads, wollastonite, etc.

[0024] The additive can also be an ultraviolet absorber. Adding an ultraviolet absorber can absorb ultraviolet light waves or reduce the transmission of ultraviolet light to prevent light aging of the ground film. The ultraviolet absorber can be ultraviolet absorber UV-9, ultraviolet absorber UV-531, ultraviolet absorber UV-0, ultraviolet absorber DOBP, etc.

[0025] As a further technical solution, when the auxiliary agent includes a filler, the filler is polylactic acid-amino composite mica powder.

[0026] Mica powder has a higher light transmittance than any other inorganic powder, better infrared blocking properties than talc and kaolin, and also provides reinforcement. Therefore, the present invention utilizes polylactic acid-amino-composite mica powder. The polylactic acid-amino-modified mica powder improves its compatibility with the mulch film base material, thereby enhancing the film's tensile properties.

[0027] As a further technical solution, the mass ratio of the PLA to the polylactic acid-amino composite mica powder is 60:5~12, for example, it can be 60:5, 60:6, 60:7, 60:8, 60:9, 60:10, 60:11, 60:12, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0028] As a further technical solution, the raw materials of the polylactic acid-amino composite mica powder include polylactic acid-amino and mica powder in a mass ratio of 0.1~0.5:10. The mass ratio of polylactic acid-amino and mica powder in the raw materials can be 0.1:10, 0.15:10, 0.2:10, 0.25:10, 0.3:10, 0.35:10, 0.4:10, 0.45:10, 0.5:10, but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0029] In the present invention, polylactic acid-amino is polylactic acid modified with terminal amines.

[0030] As a further technical solution, the preparation method of the polylactic acid-amino composite mica powder includes the following steps: dissolving polylactic acid-amino in an organic solvent, adding mica powder, mixing evenly, and drying to obtain polylactic acid-amino composite mica powder.

[0031] In the present invention, the organic solvent may be any solvent that can dissolve polylactic acid-amino groups, such as chloroform, dichloromethane, DMSO, THF, etc., preferably chloroform.

[0032] The present invention also proposes a method for preparing a low-temperature resistant brittle cracking film, which is used to prepare the low-temperature resistant brittle cracking film, comprising the following steps: melting and mixing the raw materials evenly, co-extruding, and blow molding to obtain the low-temperature resistant brittle cracking film.

[0033] As a further technical solution, the following steps are included: PLA, PBAT, PLA-PEG-NH2 and PBAT grafted GMA are melt-blended, and the remaining raw materials are added and melt-mixed uniformly, and then co-extruded and blow-molded to obtain a low-temperature brittle crack-resistant ground film.

[0034] The present invention also provides a low-temperature resistant brittle cracking ground film or the application of the low-temperature resistant brittle cracking ground film prepared by the preparation method in ground films.

[0035] The working principle and beneficial effects of the present invention are: In the present invention, PLA-PEG-NH2 and polyolefin grafted maleic anhydride are used as compatibilizers to improve the compatibility of PE with polar PBAT and PLA blends, and the provided ground film has good toughness at low temperatures, thereby achieving the effect of improving the low-temperature brittle crack resistance of the ground film. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0037] In the following examples and comparative examples, the parameters of each raw material are as follows: PLA is PLA Hisun Bio REVODE190; PBAT is BASF C1200 from Germany; PE is LLDPE Sinopec DFDA-7042; Polyolefin grafted maleic anhydride is LLDPE grafted maleic anhydride Dow 41E710; PLA-PEG-NH2 was purchased from Shanghai Tuoyang Biotechnology Co., Ltd., product number P002031, where the Mw of PEG was 2000; PBAT grafted GMA was purchased from Dongguan Shengli New Materials Co., Ltd., product number 15421; The mica powder is 1250 mesh.

[0038] Example 1 Materials: 60 parts of PLA, 30 parts of PBAT, 10 parts of PE, 5 parts of compatibilizer (the compatibilizer is PLA-PEG-NH2 and polyolefin grafted maleic anhydride in a mass ratio of 1:2), and 8 parts of mica powder; PLA, PBAT, PE, compatibilizer, and mica powder were melt-blended at 185°C for 20 minutes, extruded, and blow-molded to obtain a low-temperature, brittle-resistant ground film with a thickness of 0.08 mm.

[0039] Example 2 Materials: 60 parts of PLA, 40 parts of PBAT, 15 parts of PE, 1 part of compatibilizer (the compatibilizer is PLA-PEG-NH2 and polyolefin grafted maleic anhydride in a mass ratio of 1:2), 1 part of antioxidant 1010, and 0.5 parts of ultraviolet absorber UV-531; PLA, PBAT, PE, compatibilizer, antioxidant 1010, and ultraviolet absorber UV-531 were melt-blended at 175°C for 30 minutes, extruded, and blow-molded to obtain a low-temperature, brittle-resistant ground film with a thickness of 0.08 mm.

[0040] Example 3 Materials: 60 parts PLA, 30 parts PBAT, 10 parts PE, 5 parts compatibilizer (the compatibilizer is a mixture of PLA-PEG-NH2 and PBAT grafted with maleic anhydride in a mass ratio of 1:2, and the mixture is composed of PLA-PEG-NH2 and PBAT grafted with GMA in a mass ratio of 4:1), 8 parts mica powder; PLA, PBAT, PLA-PEG-NH2 and PBAT grafted GMA were melt-blended at 185°C for 8 minutes, and then the remaining raw materials were added and blended for 12 minutes. The mixture was extruded and blow-molded to obtain a low-temperature, brittle-resistant ground film with a thickness of 0.08 mm.

[0041] Example 4 The only difference from Example 3 is that the compatibilizer is a mixture of polyolefin grafted maleic anhydride in a mass ratio of 1:1.

[0042] Example 5 The only difference from Example 3 is that the compatibilizer is a mixture of polyolefin grafted maleic anhydride in a mass ratio of 3:1.

[0043] Example 6 The only difference from Example 3 is that the compatibilizer is a mixture of polyolefin grafted maleic anhydride in a mass ratio of 4:1.

[0044] Example 7 The only difference from Example 3 is that the compatibilizer is a mixture of polyolefin grafted maleic anhydride in a mass ratio of 7:1.

[0045] Example 8 Materials: 60 parts PLA, 30 parts PBAT, 10 parts PE, 5 parts compatibilizer (the compatibilizer is a mixture of PLA-PEG-NH2 and PBAT grafted with maleic anhydride in a mass ratio of 1:2, and the mixture is composed of PLA-PEG-NH2 and PBAT grafted with GMA in a mass ratio of 4:1), 8 parts mica powder; PLA, PBAT, PE, compatibilizer, and mica powder were melt-blended at 185°C for 20 minutes, extruded, and blow-molded to obtain a low-temperature, brittle-resistant ground film with a thickness of 0.08 mm.

[0046] Example 9 The only difference from Example 5 is that the mica powder is polylactic acid-amino composite mica powder, which is prepared by the following method: 0.1 parts of polylactic acid-amino are dissolved in 20 parts of chloroform, 10 parts of mica powder are added, stirred at 800 rpm for 20 minutes, and dried to obtain polylactic acid-amino composite mica powder.

[0047] Example 10 The only difference from Example 5 is that the mica powder is polylactic acid-amino composite mica powder, which is prepared by the following method: 0.3 parts of polylactic acid-amino are dissolved in 20 parts of chloroform, 10 parts of mica powder are added, stirred at 1000 rpm for 15 minutes, and dried to obtain polylactic acid-amino composite mica powder.

[0048] Example 11 The only difference from Example 5 is that the mica powder is polylactic acid-amino composite mica powder, which is prepared by the following method: 0.5 parts of polylactic acid-amino are dissolved in 20 parts of chloroform, 10 parts of mica powder are added, stirred at 1200 rpm for 10 minutes, and dried to obtain polylactic acid-amino composite mica powder.

[0049] Comparative Example 1 The only difference from Example 1 is that PLA-PEG-NH2 is replaced by an equal amount of PLA-PEG (PEG Mw=2k).

[0050] Comparative Example 2 The only difference from Example 1 is that the compatibilizer is polyolefin grafted maleic anhydride.

[0051] Comparative Example 3 The only difference from Example 1 is that no compatibilizer is added.

[0052] Performance test of the ground films prepared in the examples and comparative examples: Refer to the method in GB / T 35795-2017 to test the nominal strain at break before low-temperature treatment and the nominal strain at break after low-temperature treatment at -20℃ for 3h to evaluate the low-temperature brittle cracking resistance of the ground film; Refer to the method in GB / T 35795-2017 for tensile load test to evaluate the tensile properties of the ground film; The test results are recorded in Table 1 and Table 2.

[0053] Table 1 Test results of low temperature brittle crack resistance of ground film

[0054] As can be seen from Table 1, the mulch provided by the present invention has a longitudinal fracture nominal strain of more than 153% and a transverse fracture nominal strain of more than 268% at a low temperature of -20°C, and has good low-temperature resistance to brittle cracking.

[0055] Table 2 Tensile performance test results of ground film

[0056] It can be seen from Table 2 that the transverse and longitudinal tensile loads of the mulch films obtained in Examples 9 to 11 are higher than those in Example 5, indicating that the polylactic acid-amino modification of the mica powder improves the tensile properties of the mulch films.

[0057] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-temperature anti-brittle cracking ground film, characterized in that: The raw materials include the following components: PLA, PBAT, PE and a compatibilizer; the compatibilizer includes PLA-PEG-NH2 and polyolefin grafted maleic anhydride.

2. The low-temperature anti-brittle cracking ground film according to claim 1, characterized in that: The compatibilizer also includes PBAT grafted GMA.

3. The low-temperature anti-brittle cracking ground film according to claim 2, characterized in that: The mass of the PLA-PEG-NH2 and PBAT grafted GMA is greater than or equal to the mass of the polyolefin grafted maleic anhydride.

4. The low-temperature anti-brittle cracking ground film according to claim 3, characterized in that: The mass ratio of the PLA-PEG-NH2 and PBAT grafted GMA to the polyolefin grafted maleic anhydride is 3 to 4:

1.

5. The low-temperature anti-brittle cracking ground film according to claim 4, characterized in that: The mass ratio of the PLA-PEG-NH2 and PBAT grafted GMA is 3-5:

1.

6. The low-temperature anti-brittle cracking ground film according to claim 1, characterized in that: The raw materials also include auxiliary agents; the auxiliary agents include one or more of antioxidants, fillers, and ultraviolet absorbers.

7. The low-temperature anti-brittle cracking ground film according to claim 6, characterized in that: When the auxiliary agent includes a filler, the filler is polylactic acid-amino composite mica powder.

8. A method for preparing a low-temperature resistant cracking ground film, for preparing the low-temperature resistant cracking ground film according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: melting and mixing the raw materials uniformly, co-extruding, and blow molding to obtain a low-temperature anti-brittle cracking ground film.

9. A method for preparing a low-temperature resistant cracking ground film, for preparing the low-temperature resistant cracking ground film according to any one of claims 2 to 7, characterized in that: The following steps are involved: PLA, PBAT, PLA-PEG-NH2 and PBAT grafted GMA are melt-blended, and the remaining raw materials are added and melt-mixed uniformly, and then co-extruded and blow-molded to obtain a low-temperature brittle crack-resistant ground film.

10. Use of the low-temperature resistant cracking mulch film according to any one of claims 1 to 6 or the low-temperature resistant cracking mulch film prepared by the preparation method according to any one of claims 8 to 9 in mulch films.

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