A hydrophobic foamed mulch composition for paddy fields and a preparation method and application thereof

Abstract

The application discloses a hydrophobic foam mulch composition for paddy fields and a preparation method and application thereof, and belongs to the field of agricultural mulch. The composition comprises the following raw materials in parts by weight: tung oil 100 parts, tung oil-based emulsifier 0.5-10 parts, modified nanocellulose fiber 0.1-1.0 parts, fluorine-based surfactant 0.01-0.1 parts, and foaming agent 0.01-0.1 parts. The tung oil-based emulsifier is prepared by Diels-Alder reaction of tung oil and maleic anhydride to form tung oil anhydride, and then reacting the tung oil anhydride with acrylate and neutralizing. After mixing the above raw materials, high-speed stirring is performed, and carbon dioxide gas is introduced at the same time to obtain uniform and stable foam, and the hydrophobic foam mulch is formed after spraying. The hydrophobic foam mulch can be used in paddy fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural mulching film technology, and in particular to a hydrophobic foam mulching film for paddy fields and a preparation method thereof. BACKGROUND

[0002] Rice is one of the most important food crops in the world, especially in Asia, it is the main food source of many countries. Therefore, improving rice yield and quality is of great significance to ensure world food security. Water management in rice fields is an important issue. Traditional rice field management often involves a large amount of water consumption, while water evaporation is fast and water retention is poor, resulting in low irrigation efficiency. In agricultural production, the use of mulch can effectively improve soil temperature, maintain soil moisture, prevent weed growth, and reduce soil erosion. Although traditional plastic mulch has excellent heat and water retention effects, it has the disadvantages of easy breakage and difficult degradation, causing long-term "white pollution" to the environment. With the increasing awareness of environmental protection and the demand for sustainable development, developing new environmentally friendly materials to replace traditional plastic mulch has become a research hotspot.

[0003] As a new agricultural technology product, liquid mulch has been widely used and popularized in recent years. However, although liquid mulch shows its advantages in many aspects, its application in paddy fields is limited due to the hydrophilic nature of its raw materials. In the paddy field environment, the hydrophilic material of the liquid mulch will quickly dissolve in the water, because the hydrophilic material itself has the characteristics of water absorption and dissolution, and in the long-term soaking of the water environment, the liquid mulch is difficult to maintain its integrity, thus it cannot form a durable and effective cover. In addition, the liquid mulch lacks sufficient toughness after film formation and is prone to cracking. In the paddy field, this problem will be more prominent due to the flow of water and the movement of the land. Therefore, it is particularly important and urgent to develop a new type of degradable and excellent hydrophobic mulch. SUMMARY

[0004] The purpose of the present application is to solve the problems in the prior art, and to provide a hydrophobic foam mulch for paddy fields and a preparation method thereof, which not only has good heat and moisture retention capacity, but also has excellent hydrophobicity and degradability, thereby solving the problem of environmental pollution caused by traditional plastic mulch.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A hydrophobic foam mulch composition for paddy fields, comprising the following raw materials by weight: tung oil 100 parts, tung oil-based emulsifier 0.5-10 parts, modified nanocellulose fiber 0.1-1.0 parts, surfactant 0.01-0.1 parts, foaming agent 0.01-0.1 parts;

[0007] The tung oil-based emulsifier is prepared by Diels-Alder reaction of tung oil and maleic anhydride to form tung oil anhydride, and then reacting the tung oil anhydride with acrylate and neutralizing.

[0008] Preferably, the molar ratio of the tung oil, maleic anhydride and acrylate is 1:(1-5):(1-5).

[0009] Preferably, the tung oil and maleic anhydride are mixed and heated and stirred until the solid is dissolved, and then the temperature is raised to 100±10°C and stirred for 1±0.2h to obtain the tung oil anhydride; then methyl acrylate, a catalyst and a polymerization inhibitor are added, and the reaction is carried out at 100±10°C for 2±0.5h, and then the temperature is lowered and NaOH solution is added for neutralization to obtain the tung oil-based emulsifier; the stirring speed is 300-500rpm, and the concentration of the sodium hydroxide (NaOH) solution is 0.05mol / L.

[0010] Preferably, the catalyst is at least one of triethylamine, diethylamine and pyridine, and the amount of the catalyst is 1.0±0.5% of the total mass of the raw materials; the polymerization inhibitor is at least one of p-methoxyphenol and hydroquinone, and the amount of the polymerization inhibitor is 0.3±0.1% of the total mass of the raw materials; the content of tung oil glyceride in the tung oil is 84±10%.

[0011] Preferably, the tung oil-based emulsifier is 2%-5% of the mass of the tung oil.

[0012] Preferably, the raw materials are proportioned as follows: 100 parts of tung oil, 3±1 parts of the tung oil-based emulsifier, 0.5-1.0 parts of modified nanocellulose fiber, 0.05-0.1 parts of surfactant and 0.05-0.1 parts of foaming agent.

[0013] The modified nanocellulose fiber has a diameter of 3-5nm and a length of 500-1000nm.

[0014] Preferably, the modified nanocellulose fiber is prepared by blending nanocellulose gel with high molecular weight polyethylene oxide (PEO, Mv≈790000) and then freeze-drying, and the polyethylene oxide accounts for 0.1±0.06wt% of the nanocellulose fiber.

[0015] Preferably, the surfactant includes FS-31 (Yiqi Element), GS-FC829, GS-2478

[0016] one or more of Span 20 and Lutensol TO-3 (BASF).

[0017] Preferably, the foaming agent is KF-F5 (Cangzhou Kefeng); the acrylate is one or more of 2-hydroxyethyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl methacrylate.

[0018] The application of the composition in the preparation of hydrophobic foam mulch film involves mixing tung oil, tung oil-based emulsifier, modified nanocellulose fiber, surfactant and foaming agent, stirring at high speed, and simultaneously introducing carbon dioxide gas to obtain uniform and stable foam, which is then sprayed to form a hydrophobic foam mulch film.

[0019] Preferably, the hydrophobic foam mulch is applied in paddy fields.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The mulch film material exists in the form of foam. When using it, it can be sprayed directly onto the paddy field to form a film. The foam has excellent hydrophobic properties, which can not only stably cover the paddy field, but also improve the erosion resistance of the mulch film, thus achieving water retention and moisture conservation of the soil.

[0022] (2) The main component of the foam mulch is derived from tung oil, a plant oil, which has excellent degradability. Compared with traditional liquid mulch, the mulch is degradable and not easy to crack, and can be applied to soil surfaces with different morphologies.

[0023] (3) The main component of this foam mulch is tung oil, which is widely available and inexpensive, and its use in foam mulch can reduce costs. The foam solution prepared in this way can be sprayed using existing agricultural spraying equipment, making it easy to industrialize. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof.

[0025] Figure 1 The hydrophobic foam prepared in Example 1 ( Figure 1 a) and the foam stabilizing on the water surface ( Figure 1 b) A photograph of the morphology taken 2 hours later;

[0026] Figure 2 The hydrophobic foam prepared in Example 2 ( Figure 2 a) and the foam stabilizing on the water surface ( Figure 2 b) A photograph of the morphology taken 2 hours later;

[0027] Figure 3 The hydrophobic foam prepared in Example 3 ( Figure 3 a) and the foam stabilizing on the water surface ( Figure 3 b) A photograph of the morphology taken 2 hours later;

[0028] Figure 4 : Hydrophobic foam made from Example 4 (a) and the foam stabilized on the water surface (b) 2h after; Figure 4 Figure 4 : Hydrophobic foam made from Example 4 (a) and the foam stabilized on the water surface (b) 2h after;

[0029] Figure 5 : Hydrophobic foam made from Example 5 (a) and the foam stabilized on the water surface (b) 2h after; Figure 5 Figure 5 : Hydrophobic foam made from Example 5 (a) and the foam stabilized on the water surface (b) 2h after;

[0030] Figure 6 : Hydrophobic foam made from Comparative Example 1 (a) and the foam stabilized on the water surface (b) 2h after; Figure 6 Figure 6 : Hydrophobic foam made from Comparative Example 1 (a) and the foam stabilized on the water surface (b) 2h after;

[0031] Figure 7 : Photographs of the hydrophobic foam made from Example 3 before and after spraying.

[0032] Figure 8 : Photographs of the hydrophobic foam made from Example 3 1 day, 3 days and 7 days after spraying.

[0033] Figure 9 : Photographs of the hydrophobic foam made from Comparative Example 1 1 day, 3 days and 7 days after spraying.

[0034] Figure 10 Flow chart for the preparation of the tung oil-based emulsifier of the present application. DETAILED DESCRIPTION

[0035] In order to better understand the technical solutions of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application. The above and other technical features and advantages of the present application will be described in more detail below in conjunction with the embodiments.

[0036] The raw materials, reagents and the like used without the manufacturer indicated are all conventional products that can be obtained by market purchase. The chemical raw materials used in the following embodiments are all commercially available, chemically pure reagents. The tung oil is purchased from the Aldrich Company, and the content of tung oil glyceride therein is about 84%.

[0037] ​​​The preparation method of tung oil-based emulsifier is as follows: Weigh 40.5g of tung oil and 11.3g of maleic anhydride and add them to a 150mL three-necked flask equipped with a condenser and a mechanical stirrer. Heat to 60℃, and after the solid dissolves, stir evenly. Then raise the temperature to 100℃ and react at this temperature for 1 hour, with the stirring speed set to 400rpm to obtain tung oil anhydride. Add 14.3g of 2-hydroxyethyl methacrylate, 0.66g of triethylamine, and 0.198g of p-methoxyphenol and react at 100℃ for 2 hours. After cooling, neutralize with an equivalent amount of NaOH solution to obtain tung oil-based emulsifier. Transfer to a black bottle and store in a cool, ventilated place for later use.

[0038] Example 1

[0039] Weigh out 100 parts of tung oil, 0.5 parts of self-made tung oil-based emulsifier, 0.3 parts of modified nanocellulose fiber, and a co-emulsifier. 0.01 parts of FS-31 and 0.08 parts of foaming agent KF-F5 were mixed evenly at room temperature. After adjusting the CO2 flow valve until the gas flow rate was stable, CO2 gas was injected into the mixture for 5.0 min to obtain hydrophobic foam 1.

[0040] Example 2

[0041] Weigh 100 parts of tung oil, 2.0 parts of self-made tung oil-based emulsifier, 0.3 parts of modified nanocellulose fiber, 0.05 parts of co-emulsifier LutensolTO-3, and 0.08 parts of foaming agent KF-F5. Mix them evenly at room temperature. Adjust the CO2 flow valve until the gas flow rate is stable. Then inject CO2 gas into the mixture for 5.0 min to obtain hydrophobic foam 2.

[0042] Example 3

[0043] Weigh 100 parts of tung oil, 3.0 parts of self-made tung oil-based emulsifier, 0.5 parts of modified nanocellulose fiber, 0.05 parts of co-emulsifier Span 20, and 0.08 parts of foaming agent KF-F5. Mix them evenly at room temperature. Adjust the CO2 flow valve until the gas flow rate is stable. Then inject CO2 gas into the mixture for 5.0 minutes to obtain hydrophobic foam 3.

[0044] Example 4

[0045] Weigh 100 parts of tung oil, 3.0 parts of self-made tung oil-based emulsifier, 0.8 parts of modified nanocellulose fiber, 0.1 parts of co-emulsifier GS-2478, and 0.08 parts of foaming agent KF-F5. Mix them evenly at room temperature. Adjust the CO2 flow valve until the gas flow rate is stable. Then inject CO2 gas into the mixture for 5.0 minutes to obtain hydrophobic foam 4.

[0046] Example 5

[0047] Take 100 parts of tung oil, 5.0 parts of self-made tung oil-based emulsifier, 1.0 part of modified nanocellulose fiber, 0.01 part of co-emulsifier GS-FC829 and 0.08 part of foaming agent KF-F5, mix uniformly at room temperature, adjust the CO2 flow valve until the gas flow rate is stable, then inject CO2 gas into the mixed solution for 5.0 min, and obtain hydrophobic foam 5.

[0048] Comparative Example 1

[0049] Take 100 parts of tung oil, 0.5 parts of modified nanocellulose fiber, 0.1 parts of co-emulsifier FS-31 and 0.1 parts of foaming agent KF-F5, mix uniformly at room temperature, adjust the CO2 flow valve until the gas flow rate is stable, then inject CO2 gas into the mixed solution for 5.0 min, and obtain foam 6.

[0050] Short-term drainage rate: the short-term drainage rate refers to the volume of the drainage liquid within 2h after the foam is foamed, accounting for the percentage of the initial volume after foaming.

[0051] Short-term drainage rate ε = V / V1*100, where V is the drainage volume and V1 is the foam volume.

[0052] The stability of the foam is determined by the short-term drainage rate of the foam. The stability is "very good" when the drainage rate is less than 10% (volume ratio), "good" when the drainage rate is 10%-15% (volume ratio), and "poor" when the drainage rate is greater than 15% (volume ratio).

[0053] Table 1

[0054]

[0055] "a" measures whether the foam disappears on the water interface after 2h (measured by the amount of sprayed liquid: 50g±1 / m 2 ).

[0056] According to the data in Table 1, it can be seen from Examples 1-3 (in combination with Figure 1 , Figure 2 and Figure 3 ) that as the amount of tung oil-based emulsifier increases, the stability of the foam increases continuously, and the foam produced becomes fine and uniform. This is because the tung oil-based emulsifier contains a sodium carboxylate group, and the carboxyl functional group increases the hydrophilicity of the molecule, making emulsification possible. As the content of the tung oil-based emulsifier increases, the emulsifying capacity increases continuously. According to Examples 1-5 ( Figures 1-5 ) and Comparative Example 1 ( Figure 6 ​As can be seen from the results of the above experiment, the foams of Examples 1-5 can all be stable on the water surface after 7 days, while the foams of the comparative examples have gradually dissipated; as can be seen from Table 1, the foams of Examples 1-5 are still stable on the water surface after 7 days, while the foams of the comparative examples have disappeared. This shows that the addition of tung oil-based emulsifiers can improve the stability of hydrophobic foams. This is because the tung oil molecule contains long-chain non-polar hydrocarbon groups, which account for a large proportion in the molecule and give tung oil good hydrophobic properties. Tung oil forms tung oil anhydride and tung oil acid anhydride ester by reacting with maleic anhydride, acrylic ester and other substances, and these derivatives retain the hydrophobic properties of tung oil, while introducing new functional groups to enhance the interaction with other substances. This feature makes it possible for the foam to be applied to paddy fields.

[0057] In order to further test the stability of the hydrophobic foam, Examples 3 and Comparative Example 1 were taken as examples, and the foams were uniformly sprayed on the surface of the water-containing soil, and the stability of the foams was observed at different times. As shown in Figs. 1 and 2, the amount of foam gradually decreased with time. Compared with Comparative Example 1, the foam in Example 3 was still uniformly covered on the soil surface after one week, while the foam in Comparative Example 1 was significantly reduced, exposing part of the soil and accelerating the evaporation of soil moisture. This is because no tung oil-based emulsifier was added in Comparative Example 1, resulting in a decrease in the stability of the foam. Figure 8 、 9

[0058] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. A hydrophobic foamed mulch composition for use in watered fields, characterized in that, The raw materials include the following parts by weight: 100 parts tung oil, 0.5-10 parts tung oil-based emulsifier, 0.1-1.0 parts modified nanocellulose fiber, 0.01-0.1 parts surfactant, and 0.01-0.1 parts foaming agent; The modified nanocellulose fibers are prepared by freeze-drying after blending nanocellulose gel with high molecular weight polyethylene oxide, with polyethylene oxide accounting for 0.1±0.06 wt% of the nanocellulose fibers; the modified nanocellulose fibers have a diameter of 3-5 nm and a length of 500-1000 nm. The tung oil-based emulsifier is obtained by reacting tung oil with maleic anhydride via a Diels-Alder reaction to form tung oil anhydride, adding acrylate, a catalyst and a polymerization inhibitor, reacting at 100±10℃ for 2±0.5h, cooling and then adding NaOH solution to neutralize.

2. The composition of claim 1, wherein, The molar ratio of tung oil, maleic anhydride and acrylate is 1:(1~5):(1~5).

3. The composition of claim 2, wherein, Tung oil and maleic anhydride are mixed, heated and stirred until the solid dissolves. Then the temperature is raised to 100±10℃ and stirred for 1±0.2 h to obtain tung oil anhydride. The acrylate is methacrylate.

4. The composition of claim 1, wherein, The catalyst is at least one of triethylamine, diethylamine, and pyridine, and the amount of catalyst used is 1.0±0.5% of the total mass of the raw materials; the polymerization inhibitor is at least one of p-methoxyphenol and hydroquinone, and the amount of polymerization inhibitor used is 0.3±0.1% of the total mass of the raw materials; the content of tung oil glycerol ester is 84±10%.

5. The composition according to claim 1 or 2 or 4, characterized in that, The tung oil-based emulsifier is 2%-5% of the mass of tung oil.

6. The composition according to claim 5, characterized in that, The raw material ratio is as follows: 100 parts tung oil, 3±1 parts tung oil-based emulsifier, 0.5-1.0 parts modified nanocellulose fiber, 0.05~0.1 parts surfactant, and 0.05~0.1 parts foaming agent.

7. The composition according to claim 6, characterized in that, The surfactant includes one or more of Capstone® FS-31, GS-FC829, GS-2478, Span 20, and Lutensol TO-3; the foaming agent is KF-F5; and the acrylate is one or more of 2-hydroxyethyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl methacrylate.

8. The composition according to claim 3, characterized in that, The tung oil-based emulsifier is 2%-5% of the mass of tung oil.

9. The composition according to claim 8, characterized in that, The raw material ratio is as follows: 100 parts tung oil, 3±1 parts tung oil-based emulsifier, 0.5-1.0 parts modified nanocellulose fiber, 0.05~0.1 parts surfactant, and 0.05~0.1 parts foaming agent.

10. The composition according to claim 9, characterized in that, The surfactant includes one or more of Capstone® FS-31, GS-FC829, GS-2478, Span 20 and Lutensol TO-3; the foaming agent is KF-F5.

11. The use of the composition according to any one of claims 1 to 10 in the preparation of hydrophobic foam mulch films.

12. The application according to claim 11, characterized in that, Tung oil, tung oil-based emulsifier, modified nanocellulose fiber, surfactant and foaming agent are mixed and stirred at high speed while carbon dioxide gas is introduced to obtain uniform and stable foam, which forms a hydrophobic foam mulch film after spraying.

13. The application according to claim 12, characterized in that, The hydrophobic foam mulch film is used in paddy fields.

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