Low-temperature anti-brittle cracking mulch film, and preparation method and application thereof

Abstract

The application relates to the technical field of high polymer materials, and discloses a low-temperature brittle-fracture-resistant mulch film as well as a preparation method and application thereof. The low-temperature brittle-fracture-resistant mulch film is prepared from the following raw materials: PLA, PBAT, PE and a compatibilizer. The compatibilizer comprises PLA-PEG-NH2 and polyolefin grafted maleic anhydride. Through the technical scheme, the problem that PE is incompatible with polar PBAT and PLA in related technologies, leading to the low-temperature brittle fracture of the mulch film, is solved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a low-temperature brittle-resistant mulch film, its preparation method, and its application. Background Technology

[0002] Mulch film is a polymer compound, a type of plastic film promoted for agricultural use by the state, which has the functions of warming and moisturizing, and promoting crop growth. Traditional mulch film is generally made of polyethylene (PE), but with the development of technology, polylactic acid (PLA) is now widely used in the processing of mulch film, replacing traditional PE mulch film.

[0003] Polylactic acid (PLA), also known as polylactide, is chemically synthesized using lactic acid, a product of microbial fermentation, as a monomer. It has the advantage of being biodegradable after use and does not pollute the environment, thus mitigating the pollution caused by polyethylene mulch films to some extent. However, PLA has poor impact and tear resistance. To address this issue, PBAT is used to toughen PLA. Blends of PBAT and PLA are used as mulch film materials, combining the plasticity, heat resistance, and physical processing properties of PLA with the tensile properties and flexibility of PBAT.

[0004] The mulch film used in winter greenhouses needs to have good low-temperature resistance, and should not easily break or crack at low temperatures. However, when PBAT and PLA blends are used as mulch film, their low-temperature resistance is poor. To improve low-temperature resistance, PE, which has good low-temperature resistance, can be added to the blend. However, PBAT and PLA both contain a large number of ester groups and are polar polymers, while PE is a hydrocarbon polymer and is highly non-polar. It is incompatible with the polar PBAT and PLA blend, resulting in a very limited effect of adding PE on improving the low-temperature resistance of the PBAT and PLA blend. Summary of the Invention

[0005] This invention proposes a low-temperature anti-brittle cracking mulch film, its preparation method and application, which solves the problem of incompatibility between PE and polar PBAT and PLA blends in related technologies.

[0006] The technical solution of the present invention is as follows:

[0007] A low-temperature resistant and crack-resistant mulch film, the raw materials of which include the following components:

[0008] PLA, PBAT, PE, and compatibilizers; the compatibilizers include PLA-PEG-NH2 and polyolefin-grafted maleic anhydride.

[0009] In this invention, PLA-PEG-NH2 is polylactic acid-polyethylene glycol-amino.

[0010] In this invention, PLA can be any conventional PLA material in the art, such as PLA Haizheng Bio REVODE190, PLA Total LX175, PLA Fengyuan Chemical FY802, PLA Anhui Fengyuan FY602, etc., preferably PLA Haizheng Bio REVODE190.

[0011] In this invention, PBAT can be any conventional PBAT material in the art, such as PBAT Sinopec degraded material TA159, PBAT Zhejiang Huafeng HF101, PBAT Changchun ECO-A05, PBAT Changchun ECO-A20, PBAT BASF C1200, etc., preferably PBAT BASF C1200.

[0012] In this invention, PE can be any conventional PE material in the art, such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), or linear low-density polyethylene (LLDPE), preferably LLDPE, because it has excellent low-temperature resistance and can still maintain a certain toughness at low temperatures. Its impact resistance at low temperatures is significantly improved compared to LDPE, and more preferably LLDPE is Sinopec DFDA-7042.

[0013] In this invention, the polyolefin grafted with maleic anhydride can be any conventional polyolefin grafted with maleic anhydride material in the art, such as PE grafted with maleic anhydride or PP grafted with maleic anhydride, preferably PE grafted with maleic anhydride, more preferably LLDPE grafted with maleic anhydride, such as LLDPE grafted with maleic anhydride Dow 41E710.

[0014] In this invention, the mass ratio of PLA, PBAT, PE and compatibilizer can be any conventional amount in the art. The preferred mass ratio is 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 it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] As a further technical solution, the compatibilizer also includes PBAT grafted with GMA.

[0016] In this invention, PBAT grafted GMA can be any conventional material with any grafting ratio in the art. The addition of PBAT grafted GMA improves the overall compatibility of the base material in the mulch film and further improves the low-temperature resistance to brittleness of the mulch film.

[0017] As a further technical solution, the mass of PLA-PEG-NH2 and PBAT grafted with GMA is equal to the mass of polyolefin grafted with maleic anhydride.

[0018] In this invention, the mass of PLA-PEG-NH2 and PBAT grafted with GMA and the mass of polyolefin grafted with maleic anhydride are further limited, which further improves the low-temperature resistance of the mulch film to brittleness.

[0019] As a further technical solution, the mass ratio of PLA-PEG-NH2 and PBAT grafted with GMA to that of polyolefin grafted with maleic anhydride is 3~4:1.

[0020] In this invention, the mass ratio of PLA-PEG-NH2 and PBAT grafted GMA to polyolefin grafted maleic anhydride is further limited to 3~4:1, which further improves the low-temperature resistance of the mulch film to brittleness.

[0021] As a further technical solution, the mass ratio of PLA-PEG-NH2 and PBAT grafted GMA is 3~5:1.

[0022] As a further technical solution, the raw materials also include additives; the additives include one or more of antioxidants, fillers, and ultraviolet absorbers.

[0023] In this invention, the raw materials for the mulch film may further include additives.

[0024] Additives can be antioxidants. Adding antioxidants can delay or inhibit the oxidation reaction of mulch film caused by oxygen or ozone in the atmosphere during storage, transportation, processing and use, which would lead to a significant reduction in performance such as impact strength, tensile strength, flexural strength and elongation at break. Antioxidants can prevent mulch film aging and extend its service life. Antioxidants can be antioxidant 1010, antioxidant 300, antioxidant 168, antioxidant 1076, antioxidant 264, antioxidant 3114, etc.

[0025] 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 mulch film, reduce molding shrinkage, and improve product precision. Fillers can be calcium carbonate, talc, kaolin, mica powder, barium sulfate, glass microspheres, wollastonite, etc.

[0026] Additives can also be ultraviolet absorbers. Adding ultraviolet absorbers can absorb ultraviolet light waves or reduce the transmission of ultraviolet light to prevent photoaging of the mulch film. Ultraviolet absorbers can be ultraviolet absorbers such as UV-9, UV-531, UV-0, and DOBP.

[0027] As a further technical solution, when the additive includes a filler, the filler is polylactic acid-amino composite mica powder.

[0028] Mica powder has better light transmittance than any other inorganic powder, superior infrared blocking properties compared to talc and kaolin, and also possesses reinforcing properties. Therefore, this invention uses polylactic acid-amino composite mica powder. After modification with polylactic acid-amino, the compatibility between the mica powder and the mulch film substrate is improved, thereby enhancing the tensile properties of the mulch film.

[0029] As a further technical solution, the mass ratio of PLA to 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 it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] 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, or 0.5:10, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] In this invention, polylactic acid-amino is polylactic acid modified with terminal amine.

[0032] 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 and mixing evenly, drying to obtain polylactic acid-amino composite mica powder.

[0033] In this invention, the organic solvent can be any solvent that can dissolve polylactic acid-amino, such as chloroform, dichloromethane, DMSO, THF, etc., with chloroform being preferred.

[0034] The present invention also proposes a method for preparing a low-temperature resistant crack-resistant mulch film, which includes the following steps: melting and mixing the raw materials evenly, co-extruding, and blow molding to obtain the low-temperature resistant crack-resistant mulch film.

[0035] As a further technical solution, the following steps are included:

[0036] PLA, PBAT, PLA-PEG-NH2 and PBAT-grafted GMA are melt-blended and then mixed with the remaining raw materials. After being melt-blended and mixed evenly, the mixture is co-extruded and blow-molded to obtain a low-temperature brittle-resistant mulch film.

[0037] The present invention also proposes the application of a low-temperature resistant embrittlement mulch film or a low-temperature resistant embrittlement mulch film prepared by the aforementioned preparation method in mulch film.

[0038] The working principle and beneficial effects of this invention are as follows:

[0039] In this 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, resulting in mulch film with good toughness at low temperatures, thus improving the low-temperature resistance of mulch film to brittleness. Detailed Implementation

[0040] 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.

[0041] In the following examples and comparative examples, the parameters of each raw material are as follows:

[0042] PLA stands for PLA, and Haizheng Biotech REVODE190.

[0043] PBAT stands for BASF C1200 from Germany.

[0044] The PE is LLDPE, specifically Sinopec DFDA-7042.

[0045] The polyolefin grafted with maleic anhydride is LLDPE grafted with maleic anhydride, Dow 41E710.

[0046] PLA-PEG-NH2 was purchased from Shanghai Tuoyang Biotechnology Co., Ltd., product number P002031, where the Mw of PEG was 2000;

[0047] The PBAT-grafted GMA was purchased from Dongguan Shengli New Materials Co., Ltd., item number 15421.

[0048] The mica powder is 1250 mesh.

[0049] Example 1

[0050] Materials: 60 parts PLA, 30 parts PBAT, 10 parts PE, 5 parts compatibilizer (the compatibilizer is PLA-PEG-NH2 and polyolefin grafted maleic anhydride in a mass ratio of 1:2), 8 parts mica powder;

[0051] PLA, PBAT, PE, compatibilizer, and mica powder were melt-blended at 185°C for 20 minutes, then extruded and blow-molded to obtain a low-temperature brittle-resistant mulch film with a thickness of 0.08 mm.

[0052] Example 2

[0053] Materials: PLA 60 parts, PBAT 40 parts, PE 15 parts, compatibilizer 1 part (the compatibilizer is PLA-PEG-NH2 and polyolefin grafted maleic anhydride in a mass ratio of 1:2), antioxidant 1010 1 part, ultraviolet absorber UV-531 0.5 parts;

[0054] PLA, PBAT, PE, compatibilizer, antioxidant 1010, and UV absorber UV-531 were melt-blended at 175℃ for 30 minutes, then extruded and blow-molded to obtain a low-temperature brittle-resistant mulch film with a thickness of 0.08 mm.

[0055] Example 3

[0056] Materials: PLA 60 parts, PBAT 30 parts, PE 10 parts, compatibilizer 5 parts (the compatibilizer is a mixture of PLA-PEG-NH2 and PBAT grafted with GMA in a mass ratio of 1:2, the mixture is composed of PLA-PEG-NH2 and PBAT grafted with GMA in a mass ratio of 4:1), mica powder 8 parts;

[0057] PLA, PBAT, PLA-PEG-NH2 and PBAT grafted with GMA were melt-blended at 185℃ for 8 minutes, and then the remaining raw materials were added and blended for another 12 minutes. The mixture was then extruded and blow-molded to obtain a low-temperature brittle-resistant mulch film with a thickness of 0.08 mm.

[0058] Example 4

[0059] The only difference from Example 3 is that the compatibilizer is a mixture of maleic anhydride grafted onto polyolefin in a 1:1 mass ratio.

[0060] Example 5

[0061] The only difference from Example 3 is that the compatibilizer is a mixture of maleic anhydride grafted onto polyolefin in a mass ratio of 3:1.

[0062] Example 6

[0063] The only difference from Example 3 is that the compatibilizer is a mixture of maleic anhydride grafted onto polyolefin in a mass ratio of 4:1.

[0064] Example 7

[0065] The only difference from Example 3 is that the compatibilizer is a mixture of maleic anhydride grafted onto polyolefin in a mass ratio of 7:1.

[0066] Example 8

[0067] Materials: PLA 60 parts, PBAT 30 parts, PE 10 parts, compatibilizer 5 parts (the compatibilizer is a mixture of PLA-PEG-NH2 and PBAT grafted with GMA in a mass ratio of 1:2, the mixture is composed of PLA-PEG-NH2 and PBAT grafted with GMA in a mass ratio of 4:1), mica powder 8 parts;

[0068] PLA, PBAT, PE, compatibilizer, and mica powder were melt-blended at 185°C for 20 minutes, then extruded and blow-molded to obtain a low-temperature brittle-resistant mulch film with a thickness of 0.08 mm.

[0069] Example 9

[0070] 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 is dissolved in 20 parts of chloroform, 10 parts of mica powder are added and stirred at 800 rpm for 20 min, and then dried to obtain polylactic acid-amino composite mica powder.

[0071] Example 10

[0072] 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 and stirred at 1000 rpm for 15 min, and then dried to obtain polylactic acid-amino composite mica powder.

[0073] Example 11

[0074] 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 and stirred at 1200 rpm for 10 min, and then dried to obtain polylactic acid-amino composite mica powder.

[0075] Comparative Example 1

[0076] The only difference from Example 1 is that PLA-PEG-NH2 is replaced with an equal amount of PLA-PEG (PEG Mw=2k).

[0077] Comparative Example 2

[0078] The only difference from Example 1 is that the compatibilizer is polyolefin grafted with maleic anhydride.

[0079] Comparative Example 3

[0080] The only difference from Example 1 is that no compatibilizer is added.

[0081] Performance tests of the mulch films prepared in the examples and comparative examples:

[0082] The nominal strain at break before low-temperature treatment and the nominal strain at break after low-temperature treatment at -20℃ for 3 hours were tested according to the method in GB / T 35795-2017 to evaluate the low-temperature resistance of the mulch film to brittle fracture.

[0083] The tensile load test was conducted according to the method in GB / T 35795-2017 to evaluate the tensile properties of the mulch film.

[0084] The test results are recorded in Table 1 and Table 2.

[0085] Table 1. Results of Low-Temperature Crack Resistance Tests for Mulch Films

[0086]

[0087] As can be seen from Table 1, the mulch film provided by the present invention has a longitudinal fracture nominal strain of over 153% and a transverse fracture nominal strain of over 268% at a low temperature of -20℃, exhibiting good low-temperature resistance to brittleness.

[0088] Table 2. Tensile property test results of the mulch film

[0089]

[0090] As can be seen from Table 2, the transverse and longitudinal tensile loads of the mulch films obtained in Examples 9-11 are higher than those in Example 5, indicating that the polylactic acid-amino modification of mica powder improves the tensile properties of the mulch films.

[0091] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-temperature resistant and crack-resistant mulch film, characterized in that, The raw materials include the following components: PLA, PBAT, PE, and compatibilizers; the compatibilizers include PLA-PEG-NH2 and polyolefin grafted maleic anhydride; The mass ratio of PLA, PBAT, PE and compatibilizer is 60:30~40:10~15:1~5.

2. The low-temperature resistant crack-resistant mulch film according to claim 1, characterized in that, The compatibilizer also includes PBAT grafted with GMA.

3. The low-temperature resistant crack-resistant mulch film according to claim 2, characterized in that, The mass of PLA-PEG-NH2 and PBAT grafted with GMA and the mass of polyolefin grafted with maleic anhydride are ≥.

4. The low-temperature resistant crack-resistant mulch film according to claim 3, characterized in that, The mass ratio of PLA-PEG-NH2 and PBAT grafted with GMA to that of polyolefin grafted with maleic anhydride is 3~4:

1.

5. The low-temperature resistant crack-resistant mulch film according to claim 4, characterized in that, The mass ratio of PLA-PEG-NH2 and PBAT grafted GMA is 3~5:

1.

6. The low-temperature resistant crack-resistant mulch film according to claim 1, characterized in that, The raw materials also include additives; the additives include one or more of antioxidants, fillers, and ultraviolet absorbers.

7. The low-temperature resistant crack-resistant mulch film according to claim 6, characterized in that, When the additive includes a filler, the filler is polylactic acid-amino composite mica powder.

8. A method for preparing a low-temperature resistant crack-resistant mulch film, used to prepare the low-temperature resistant crack-resistant mulch film according to any one of claims 1 to 7, characterized in that, The process includes the following steps: after the raw materials are melted and mixed evenly, they are co-extruded and blow-molded to obtain a low-temperature brittle-resistant mulch film.

9. A method for preparing a low-temperature resistant crack-resistant mulch film, used to prepare the low-temperature resistant crack-resistant mulch film according to any one of claims 2 to 7, characterized in that, Includes the following steps: PLA, PBAT, PLA-PEG-NH2 and PBAT-grafted GMA are melt-blended and then mixed with the remaining raw materials. After being melt-blended and mixed evenly, the mixture is co-extruded and blow-molded to obtain a low-temperature brittle-resistant mulch film.

10. The application of a low-temperature resistant embrittlement mulch film according to any one of claims 1 to 6 or a low-temperature resistant embrittlement mulch film prepared by the preparation method according to any one of claims 8 to 9 in the field of mulch film.

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