A high-strength warming composite agricultural mulch film and its preparation method

Abstract

This invention relates to the field of polymer film technology and proposes a high-strength, heat-increasing composite agricultural mulch film and its preparation method. The high-strength, heat-increasing composite agricultural mulch film includes a surface layer and a base layer. The surface layer comprises the following components: PBAT, PLA, silica, and a first compatibilizer. The base layer comprises the following components: PBAT, PLA, silica, and a second compatibilizer. The first compatibilizer contains phenyl and epoxy groups in its molecular structure; the second compatibilizer contains epoxy groups but not phenyl groups. The mass of PBAT in the surface layer is greater than the mass of PLA; the mass of PBAT in the base layer is less than the mass of PLA. This technical solution solves the problem of low strength in mulch films prepared from PLA and PBAT blends in related technologies.

Description

Technical Field

[0001] This invention relates to the field of polymer film technology, specifically to a high-strength, heat-increasing composite agricultural mulch film and its preparation method. Background Technology

[0002] Mulch film is a polymer compound and a type of plastic film promoted for agricultural use by the state. It has the functions of warming and moisturizing, and promoting crop growth. With the increasing awareness of environmental protection, my country focuses on the research and development of biodegradable mulch film, and now there are photodegradable agricultural mulch films, biodegradable agricultural mulch films, and controlled photodegradable and microbial degradable agricultural mulch films.

[0003] Currently, biodegradable mulch film materials under research and development include polylactic acid (PLA), poly(adipic acid-terephthalic acid) butanediol copolyester (PBAT), polypropylene carbonate (PPC), and polyhydroxyalkanoates (PHA). PLA and PBAT blends are commonly used, but due to the poor compatibility between PLA and PBAT, the strength of the mulch film is relatively low. Summary of the Invention

[0004] This invention proposes a high-strength, heat-increasing composite agricultural mulch film and its preparation method, which solves the problem of low strength of mulch films prepared from PLA and PBAT blends in related technologies.

[0005] The technical solution of the present invention is as follows:

[0006] A high-strength, heat-increasing composite agricultural mulch film includes a surface layer and a base layer. The raw materials of the surface layer include the following components: PBAT, PLA, silica, and a first compatibilizer.

[0007] The raw materials of the base layer include the following components: PBAT, PLA, silica, and a second compatibilizer;

[0008] The molecular structure of the first compatibilizer includes phenyl and epoxy groups; the molecular structure of the second compatibilizer includes epoxy groups but does not include phenyl groups.

[0009] In the surface layer, the mass of PBAT is greater than the mass of PLA; in the base layer, the mass of PBAT is less than the mass of PLA.

[0010] The composite agricultural mulch film provided in this invention has a surface layer primarily made of PBAT. PBAT's excellent flexibility and extensibility give the mulch film good tensile and tear resistance, effectively resisting external damage. The base layer is primarily made of PLA, whose rigidity, in conjunction with the surface layer, enhances the overall structural stability of the mulch film, making it less prone to damage during installation and use, thus extending its service life. The addition of silica effectively absorbs and stores solar radiation heat, raising soil temperature through heat conduction, which is beneficial for crop growth and promotes root development and metabolism.

[0011] The composite agricultural mulch film provided in this invention uses both PBAT and PLA, both of which are biodegradable materials. After its service life, the mulch film gradually degrades in the natural environment, reducing white pollution in farmland and contributing to the green and sustainable development of agriculture. Furthermore, the different proportions of raw materials in the top and bottom layers give the mulch film excellent heat retention and moisture retention properties, effectively reducing soil moisture evaporation, maintaining soil humidity, reducing irrigation frequency, achieving water conservation and efficiency, creating an excellent soil environment for crop growth, and improving crop yield and quality.

[0012] In this invention, the first compatibilizer can be any one or more compounds containing phenyl and epoxy groups in their molecular structure, such as 4-[2-(2-epoxyethyl)ethoxy]benzoic acid 4-[2-(2-epoxyethyl)ethoxy]phenyl ester, methyl 4-(epoxyethylene methoxy)-phenylpropionate, diglycidyl phthalate, resorcinol diglycidyl ether, 1,4-bis(oxyglycidyl)benzene, preferably one or more of 4-[2-(2-epoxyethyl)ethoxy]benzoic acid 4-[2-(2-epoxyethyl)ethoxy]phenyl ester, methyl 4-(epoxyethylene methoxy)-phenylpropionate, and diglycidyl phthalate, more preferably diglycidyl phthalate.

[0013] In this invention, the second compatibilizer can be any one or more compounds whose molecular structure contains an epoxy group but does not contain a phenyl group, such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo[4.1.0]3-heptylmethyl)adipate, cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexylcarboxylate, diglycidyl adipic acid ester, etc. One or more of 1,6-hexanediol diglycidyl ether, preferably one or more of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo[4.1.0]3-heptylmethyl)adipate, cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexylcarboxylate, and adipic acid diglycidyl ester, more preferably adipic acid diglycidyl ester.

[0014] As a further technical solution, the mass ratio of PBAT to PLA in the surface layer is 60~70:30, for example, it can be 60:30, 61:30, 61.5:30, 62:30, 62.5:30, 63:30, 64:30, 65:30, 65.5:30, 66:30, 66.5:30, 67:30, 67.5:30, 68:30, 69:30, 70:30, etc., preferably 60:30 or 70:30.

[0015] As a further technical solution, the mass ratio of PLA to PBAT in the base layer is 60~70:30, for example, it can be 60:30, 61:30, 61.5:30, 62:30, 62.5:30, 63:30, 64:30, 65:30, 65.5:30, 66:30, 66.5:30, 67:30, 67.5:30, 68:30, 69:30, 70:30, etc., preferably 60:30 or 70:30.

[0016] As a further technical solution, the mass ratio of PBAT and PLA in the surface layer to silicon dioxide is 90~100:10, for example, it can be 90:10, 91:10, 91.5:10, 92:10, 92.5:10, 93:10, 93.5:10, 94:10, 94.5:10, 95:10, 95.5:10, 96:10, 96.5:10, 97:10, 97.5:10, 98:10, 99:10, 100:10, etc., preferably 90:10 or 100:10.

[0017] As a further technical solution, the mass ratio of PBAT and PLA in the base layer to silicon dioxide is 90~100:5, for example, it can be 90:10, 91:10, 91.5:10, 92:10, 92.5:10, 93:10, 93.5:10, 94:10, 94.5:10, 95:10, 95.5:10, 96:10, 96.5:10, 97:10, 97.5:10, 98:10, 99:10, 100:10, etc., preferably 90:10 or 100:10.

[0018] As a further technical solution, the mass ratio of PBAT and PLA in the surface layer to the first compatibilizer is 100:1 to 5, for example, it can be 100:1, 100:1.2, 100:1.5, 100:1.7, 100:2, 100:2.5, 100:2.8, 100:3, 100:3.5, 100:4, 100:4.2, 100:4.5, 100:4.7, 100:5, etc., preferably 100:1 or 100:5.

[0019] As a further technical solution, the mass ratio of PBAT and PLA in the base layer to the second compatibilizer is 100:1 to 5, for example, it can be 100:1, 100:1.2, 100:1.5, 100:1.7, 100:2, 100:2.5, 100:2.8, 100:3, 100:3.5, 100:4, 100:4.2, 100:4.5, 100:4.7, 100:5, etc., preferably 100:1 or 100:5.

[0020] In this invention, the thickness ratio of the surface layer to the base layer can be any ratio, such as 1:99, 1:89, 1:79, 1:69, 1:59, 1:49, 1:39, 1:29, 1:19, 1:9, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 9:1, 19:1, 29:1, 39:1, 49:1, 59:1, 69:1, 79:1, 89:1, 99:1, etc., preferably 1:4 to 4:1.

[0021] This invention also proposes a method for preparing a high-strength, heat-increasing composite agricultural mulch film, which includes the following steps: melting and mixing the raw materials of the surface layer and the raw materials of the base layer evenly, then co-extruding, blow molding, and cooling to obtain the high-strength, heat-increasing composite agricultural mulch film.

[0022] The composite agricultural mulch film of this invention is prepared using a melt-mixing co-extrusion blow molding process. The surface and base layer materials are melt-mixed separately to ensure uniform mixing of PBAT, PLA, and silica in each layer, laying the foundation for the high strength performance of the mulch film. Simultaneously, the co-extrusion process tightly bonds the surface and base layers, forming a continuous and stable composite structure, effectively preventing delamination and greatly ensuring the overall tensile and puncture resistance of the mulch film. This allows it to withstand mechanical damage during installation and use, extending its service life. Furthermore, blow molding imparts good uniformity and appropriate thickness to the mulch film, ensuring close adhesion to the soil when covering farmland, reducing heat loss, and guaranteeing warming and heat preservation effects.

[0023] The present invention also proposes the application of the high-strength heat-increasing composite agricultural mulch film or the high-strength heat-increasing composite agricultural mulch film prepared by the above preparation method in mulch film.

[0024] The working principle and beneficial effects of this invention are as follows:

[0025] In this invention, a compound containing phenyl and epoxy groups in its molecular structure is added to the surface layer as a compatibilizer, and a compound containing epoxy groups but not phenyl groups in its molecular structure is added to the base layer as a compatibilizer. This improves the compatibility of PLA and PBAT blend materials and achieves the effect of improving the strength of composite agricultural mulch film. Detailed Implementation

[0026] 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.

[0027] The parameters of the raw materials in the following examples and comparative examples are as follows:

[0028] PBAT is PBAT TH801T;

[0029] PLA stands for PLA LX175;

[0030] The particle size of silicon dioxide is 20 nm.

[0031] Example 1

[0032] S1. Mix 75 parts of PBAT, 25 parts of PLA, 10 parts of silica, and 3 parts of resorcinol diglycidyl ether at 175°C until homogeneous to obtain the surface material.

[0033] S2. Mix 30 parts of PBAT, 60 parts of PLA, 5 parts of silica, and 3 parts of 1,6-hexanediol diglycidyl ether at 175°C until homogeneous to obtain the base material.

[0034] S3. The surface material and the base material are co-extruded at 180℃, blow-molded, and cooled to obtain a high-strength heat-increasing composite agricultural mulch film with a surface:base thickness ratio of 4:1.

[0035] Example 2

[0036] S1. Mix 70 parts of PBAT, 30 parts of PLA, 10 parts of silica, and 5 parts of resorcinol diglycidyl ether at 175°C until homogeneous to obtain the surface material.

[0037] S2. Mix 30 parts of PBAT, 70 parts of PLA, 5 parts of silica, and 5 parts of 1,6-hexanediol diglycidyl ether at 175°C until homogeneous to obtain the base material.

[0038] S3. The surface material and the base material are co-extruded at 180℃, blow-molded, and cooled to obtain a high-strength heat-increasing composite agricultural mulch film with a surface:base thickness ratio of 4:1.

[0039] Example 3

[0040] S1. Mix 60 parts of PBAT, 30 parts of PLA, 10 parts of silica, and 1 part of resorcinol diglycidyl ether at 175°C until homogeneous to obtain the surface material.

[0041] S2. Mix 30 parts of PBAT, 60 parts of PLA, 5 parts of silica, and 1 part of 1,6-hexanediol diglycidyl ether at 175°C until homogeneous to obtain the base material.

[0042] S3. The surface material and the base material are co-extruded at 180℃, blow-molded, and cooled to obtain a high-strength heat-increasing composite agricultural mulch film with a surface:base thickness ratio of 4:1.

[0043] Example 4

[0044] The only difference from Example 2 is that resorcinol diglycidyl ether is replaced with an equal amount of diglycidyl phthalate.

[0045] Example 5

[0046] The only difference from Example 4 is that 1,6-hexanediol diglycidyl ether is replaced with an equal amount of adipic acid diglycidyl ester.

[0047] Comparative Example 1

[0048] S1. Mix 70 parts of PBAT, 30 parts of PLA, 10 parts of silica, and 5 parts of resorcinol diglycidyl ether at 175°C until homogeneous to obtain the surface material.

[0049] S2. Mix 30 parts of PBAT, 70 parts of PLA, 5 parts of silica, and 5 parts of resorcinol diglycidyl ether at 175°C until homogeneous to obtain the base material.

[0050] S3. The surface material and the base material are co-extruded at 180℃, blow-molded, and cooled to obtain a high-strength heat-increasing composite agricultural mulch film with a surface:base thickness ratio of 4:1.

[0051] Comparative Example 2

[0052] S1. Mix 70 parts of PBAT, 30 parts of PLA, 10 parts of silica, and 5 parts of 1,6-hexanediol diglycidyl ether at 175°C until homogeneous to obtain the surface material.

[0053] S2. Mix 30 parts of PBAT, 70 parts of PLA, 5 parts of silica, and 5 parts of 1,6-hexanediol diglycidyl ether at 175°C until homogeneous to obtain the base material.

[0054] S3. The surface material and the base material are co-extruded at 180℃, blow-molded, and cooled to obtain a high-strength heat-increasing composite agricultural mulch film with a surface:base thickness ratio of 4:1.

[0055] Comparative Example 3

[0056] S1. Mix 70 parts of PBAT, 30 parts of PLA, 10 parts of silica, and 5 parts of 1,6-hexanediol diglycidyl ether at 175°C until homogeneous to obtain the surface material.

[0057] S2. Mix 30 parts of PBAT, 70 parts of PLA, 5 parts of silica, and 5 parts of resorcinol diglycidyl ether at 175°C until homogeneous to obtain the base material.

[0058] S3. The surface material and the base material are co-extruded at 180℃, blow-molded, and cooled to obtain a high-strength heat-increasing composite agricultural mulch film with a surface:base thickness ratio of 4:1.

[0059] The composite agricultural mulch films with a thickness of 0.01 mm obtained from Examples 1-5 and Comparative Examples 1-3 were subjected to tensile load tests according to the method in GB / T 35795-2017; the test results are recorded in Table 1.

[0060] Table 1 Tensile load of composite agricultural mulch film

[0061]

[0062] As can be seen from Table 1, compared with Comparative Examples 1-3, the composite agricultural films provided in Examples 1-5 have high tensile loads and meet the requirements of various indicators in GB / T 35795-2017. This indicates that the addition of compounds with phenyl and epoxy groups in the molecular structure as compatibilizers to the surface layer and compounds with epoxy groups but no phenyl groups in the molecular structure as compatibilizers to the base layer improves the strength of the composite agricultural films.

[0063] Furthermore, compared to existing mulch films, the soil temperature at a distance of 5 cm from the mulch film provided by this invention is 2-3°C higher after testing, indicating that the composite agricultural mulch film provided by this invention has good warming and heat preservation effects.

[0064] 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 high-strength, heat-increasing composite agricultural mulch film, comprising a surface layer and a base layer, characterized in that, The raw material of the surface layer includes the following components: PBAT, PLA, silica and a first compatibilizer; The raw materials of the base layer include the following components: PBAT, PLA, silica, and a second compatibilizer; The molecular structure of the first compatibilizer includes phenyl and epoxy groups; the molecular structure of the second compatibilizer includes epoxy groups but does not include phenyl groups. The mass ratio of PBAT to PLA in the surface layer is 60~70:30; the mass ratio of PLA to PBAT in the base layer is 60~70:

30. The mass ratio of PBAT and PLA in the surface layer to the first compatibilizer is 100:1~5; The mass ratio of PBAT and PLA in the base layer to the mass ratio of the second compatibilizer is 100:1~5.

2. The high-strength, heat-increasing composite agricultural mulch film according to claim 1, characterized in that, The first compatibilizer includes one or more of the following: 4-[2-(2-epoxyethyl)ethoxy]benzoic acid 4-[2-(2-epoxyethyl)ethoxy]phenyl ester, methyl 4-(epoxyethylene methoxy)-phenylpropionate, diglycidyl phthalate, resorcinol diglycidyl ether, and 1,4-bis(oxyglycidyl)benzene; The second compatibilizer includes one or more of the following: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo[4.1.0]3-heptylmethyl)adipate, cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexylcarboxylate, adipic acid diglycidyl ester, and 1,6-hexanediol diglycidyl ether.

3. The high-strength, heat-increasing composite agricultural mulch film according to claim 2, characterized in that, The first compatibilizer includes one or more of 4-[2-(2-epoxyethyl)ethoxy]benzoic acid, methyl 4-(epoxyethylene methoxy)-phenylpropionate, and diglycidyl phthalate.

4. The high-strength, heat-increasing composite agricultural mulch film according to claim 2, characterized in that, The second compatibilizer includes one or more of the following: 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, bis(7-oxabicyclo[4.1.0]3-heptylmethyl)adipic acid ester, cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexylcarboxylate, and adipic acid diglycidyl ester.

5. The high-strength, heat-increasing composite agricultural mulch film according to claim 1, characterized in that, The mass ratio of PBAT and PLA in the surface layer to silicon dioxide is 90~100:10; The mass ratio of PBAT and PLA to silica in the base layer is 90~100:

5.

6. A high-strength, heat-increasing composite agricultural mulch film according to any one of claims 1 to 5, characterized in that, The thickness ratio of the surface layer to the base layer is 1:4 to 4:

1.

7. A method for preparing a high-strength, heat-increasing composite agricultural mulch film, used to prepare the high-strength, heat-increasing composite agricultural mulch film according to any one of claims 1 to 6, characterized in that, The process includes the following steps: melting and mixing the raw materials for the surface layer and the raw materials for the base layer evenly, then co-extruding, blow molding, and cooling to obtain a high-strength, heat-increasing composite agricultural mulch film.

8. The application of the high-strength heat-increasing composite agricultural mulch film as described in any one of claims 1 to 6, or the high-strength heat-increasing composite agricultural mulch film prepared by the preparation method described in claim 7, in mulch film.

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