Hydrophobic foam mulching film composition for paddy field as well as preparation method and application of hydrophobic foam mulching film composition

Abstract

The invention discloses a hydrophobic foam mulching film composition for paddy fields and a preparation method and application thereof, and belongs to the field of agricultural mulching films. The composition is prepared from the following raw materials in parts by weight: 100 parts of tung oil, 0.5 to 10 parts of tung oil-based emulsifier, 0.1 to 1.0 part of modified nano cellulose fiber, 0.01 to 0.1 part of fluorine surfactant and 0.01 to 0.1 part of foaming agent, the tung oil-based emulsifier is prepared by the following steps: carrying out Diels-Alder reaction on tung oil and maleic anhydride to form tung oil anhydride, carrying out reaction on the tung oil anhydride and acrylate, and neutralizing to obtain the tung oil-based emulsifier. After the raw materials are mixed, high-speed stirring is performed, meanwhile, carbon dioxide gas is introduced, uniform and stable foams are obtained, and the hydrophobic foam mulching film is formed after spraying. The hydrophobic foam mulching film can be used in paddy fields.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural mulch films, and in particular to a hydrophobic foam mulch film for paddy fields and a preparation method thereof. Background Art

[0002] Rice is one of the most important food crops in the world, especially in Asia, where it is the main food source for many countries. Therefore, improving rice yield and quality is of great significance to ensuring world food security. Water management in rice fields is an important issue. Traditional rice field management methods often involve a large amount of water resource consumption, and at the same time, water evaporates quickly and has poor water retention capacity, resulting in low irrigation efficiency. In agricultural production, the use of mulch can effectively increase soil temperature, maintain soil moisture, avoid weed growth, and reduce soil erosion. Although traditional plastic mulch has excellent heat preservation and water retention effects, it has the disadvantages of being easy to break and difficult to degrade, causing long-term "white pollution" to the environment. With the improvement of environmental awareness and the demand for sustainable development, the development of new environmentally friendly materials to replace traditional plastic mulch has become a research hotspot.

[0003] As an emerging agricultural technology product, liquid mulch has been widely used and promoted in recent years. However, although liquid mulch has shown its advantages in many aspects, its application in paddy fields is limited because its raw materials usually have a certain degree of hydrophilicity. In the paddy field environment, the hydrophilic material of the liquid mulch will dissolve rapidly in the paddy field. This is because the hydrophilic material itself has the characteristics of water absorption and dissolution. In the paddy field environment where it is immersed for a long time, it is difficult for the liquid mulch to maintain its integrity, and thus it is impossible to form a durable and effective covering layer. In addition, the liquid mulch lacks sufficient toughness after film formation and is prone to cracking. In paddy fields, this problem will be more prominent due to the flow of water and the movement of plots. Therefore, it is particularly important and urgent to develop a new type of degradable mulch with excellent hydrophobic properties. Summary of the invention

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

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A hydrophobic foam mulch composition for paddy fields comprises the following raw materials in parts by weight: 100 parts of tung oil, 0.5-10 parts of tung oil-based emulsifier, 0.1-1.0 parts of modified nanocellulose fibers, 0.01-0.1 parts of surfactants, and 0.01-0.1 parts of foaming agents;

[0007] The tung oil-based emulsifier is prepared by reacting tung oil with maleic anhydride through Diels-Alder reaction to form tung oil anhydride, and then reacting the tung oil anhydride with acrylic acid ester and neutralizing the reactant.

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

[0009] Preferably, tung oil and maleic anhydride are mixed, heated and stirred, and after the solid is dissolved, the temperature is raised to 100±10° C. and stirred for reaction for 1±0.2 h to obtain tung oil anhydride; methyl acrylate, a catalyst and an inhibitor are added, and the mixture is reacted at 100±10° C. for 2±0.5 h. After cooling, a NaOH solution is added for neutralization to obtain a tung oil-based emulsifier; the stirring speed is 300-500 rpm, and the concentration of the sodium hydroxide (NaOH) solution is 0.05 mol / 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 inhibitor is at least one of p-methoxyphenol and hydroquinone, and the amount of the inhibitor is 0.3±0.1% of the total mass of the raw materials; the content of elaeutrophin 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 material ratio is: 100 parts of tung oil, 3±1 parts of 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 3-5 nm and a length of 500-1000 nm.

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

[0015] Preferably, the surfactant comprises FS-31(Yizu Elements), GS-FC829, GS-2478

[0016] (GS Chemical), Span 20 and Lutensol TO-3 (BASF) One or more thereof.

[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 composition is used in preparing a hydrophobic foam mulch. Tung oil, a tung oil-based emulsifier, modified nanocellulose fibers, a surfactant and a foaming agent are mixed, stirred at high speed, and carbon dioxide gas is introduced to obtain uniform and stable foam, which is then sprayed to form a hydrophobic foam mulch.

[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 ground film material exists in the form of foam. When used, it can be sprayed directly on the paddy field to form a film. The foam has excellent hydrophobic properties. It can not only stably cover the paddy field, but also improve the erosion resistance of the ground film, thereby achieving water and moisture retention in the soil.

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

[0023] (3) The main component of the foam mulch is tung oil, which is widely available and inexpensive, and can be used to reduce costs. The foam solution prepared in this way can be sprayed using existing agricultural spraying equipment, which is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0025] Figure 1 : The hydrophobic foam obtained in Example 1 ( Figure 1 a) and the foam is stable on the water surface ( Figure 1 b) Morphological photos after 2 hours;

[0026] Figure 2 : The hydrophobic foam obtained in Example 2 ( Figure 2 a) and the foam is stable on the water surface ( Figure 2 b) Morphological photos after 2 hours;

[0027] Figure 3 : The hydrophobic foam obtained in Example 3 ( Figure 3 a) and the foam is stable on the water surface ( Figure 3 b) Morphological photos after 2 hours;

[0028] Figure 4 : The hydrophobic foam obtained in Example 4 ( Figure 4 a) and the foam is stable on the water surface ( Figure 4 b) Morphological photos after 2 hours;

[0029] Figure 5 : The hydrophobic foam obtained in Example 5 ( Figure 5 a) and the foam is stable on the water surface ( Figure 5 b) Morphological photos after 2 hours;

[0030] Figure 6 : The hydrophobic foam obtained in Comparative Example 1 ( Figure 6 a) and the foam is stable on the water surface ( Figure 6 b) Morphological photos after 2 hours;

[0031] Figure 7 : Photos of the hydrophobic foam prepared in Example 3 before and after spraying.

[0032] Figure 8 : Photos taken 1 day, 3 days and 7 days after the hydrophobic foam prepared in Example 3 was sprayed.

[0033] Fig. 9 : Photos of the hydrophobic foam prepared in Comparative Example 1 taken 1 day, 3 days and 7 days after spraying.

[0034] Fig.10 The figure is a flow chart of the preparation of the tung oil-based emulsifier of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in combination with the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment 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 creative work should fall within the scope of protection of the present invention. The above and other technical features and advantages of the present invention are described in more detail below in combination with the embodiments.

[0036] All raw materials and reagents used without indicating the manufacturer are conventional products that can be purchased from the market. The chemical raw materials used in the following examples are all commercially available, chemically pure reagents. Tung oil was purchased from Aladdin Company, in which the content of eleostearyl glyceride was about 84%.

[0037] The preparation method of tung oil-based emulsifier is as follows: weigh tung oil (40.5g) and maleic anhydride (11.3g) and add them to a 150mL three-necked flask equipped with a condenser and a mechanical stirrer, heat to 60°C, stir evenly after the solid is dissolved, then heat to 100°C, react at this temperature for 1h, and set the stirring speed to 400rpm to obtain tung oil anhydride. Add 2-hydroxyethyl methacrylate (14.3g), triethylamine (0.66g), and p-methoxyphenol (0.198g) and react at 100°C for 2h, cool and neutralize with an equivalent amount of NaOH solution to obtain tung oil-based emulsifier, move to a black bottle and place in a cool and ventilated place for standby use.

[0038] Example 1

[0039] Weigh 100 parts of tung oil, 0.5 parts of homemade tung oil-based emulsifier, 0.3 parts of modified nanocellulose fiber, and an emulsifier. 0.01 part of FS-31 and 0.08 part of foaming agent KF-F5 were mixed evenly at room temperature, and the CO2 flow valve was adjusted until the gas flow rate was stable, and CO2 gas was injected into the mixed liquid for 5.0 minutes to obtain hydrophobic foam 1.

[0040] Example 2

[0041] Weigh 100 parts of tung oil, 2.0 parts of homemade 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, and then inject CO2 gas into the mixed liquid for 5.0 minutes to obtain hydrophobic foam 2.

[0042] Example 3

[0043] Weigh 100 parts of tung oil, 3.0 parts of homemade 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, and inject CO2 gas into the mixed liquid for 5.0 minutes to obtain hydrophobic foam 3.

[0044] Example 4

[0045] Weigh 100 parts of tung oil, 3.0 parts of homemade 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, and then inject CO2 gas into the mixed liquid for 5.0 minutes to obtain hydrophobic foam 4.

[0046] Example 5

[0047] Weigh 100 parts of tung oil, 5.0 parts of homemade tung oil-based emulsifier, 1.0 part of modified nanocellulose fiber, 0.01 parts of co-emulsifier GS-FC829 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, and then inject CO2 gas into the mixed liquid for 5.0 minutes to obtain hydrophobic foam 5.

[0048] Comparative Example 1

[0049] Weigh 100 parts of tung oil, 0.5 parts of modified nanocellulose fiber, and an emulsifier. 0.1 part of FS-31 and 0.1 part of foaming agent KF-F5 were mixed evenly at room temperature, and the CO2 flow valve was adjusted until the gas flow rate was stable, and CO2 gas was injected into the mixed liquid for 5.0 minutes to obtain foam 6.

[0050] Short-term drainage rate: Short-term drainage rate refers to the percentage of liquid volume discharged within 2 hours after foaming to 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 measured by the short-term drainage rate of the foam. A drainage rate of less than 10% (volume ratio) indicates "very good" stability, a drainage rate of 10%-15% (volume ratio) indicates "good" stability, and a drainage rate greater than 15% (volume ratio) indicates "poor" stability.

[0053] Table 1

[0054]

[0055] "a" is used to measure whether the foam dissipates after 2 hours on the water interface (measured in terms of the amount of liquid sprayed: 50g ± 1 / m 2 ).

[0056] According to the data in Table 1, by Examples 1-3 (combined Figure 1 , Figure 2 and Figure 3 ) It can be seen that as the amount of tung oil-based emulsifier added increases, the stability of the foam increases, and the foam becomes fine and uniform. This is because the tung oil-based emulsifier contains sodium carboxylate groups, and the carboxyl functional group increases the hydrophilicity of the molecule, providing the possibility for emulsification. As the content of tung oil-based emulsifier increases, the emulsification ability continues to increase. According to Examples 1-5 ( Figure 1-5 ) and Comparative Example 1 ( Figure 6) results show that after 7 days, the foams of Examples 1-5 can be stabilized on the water surface, while the foam in the comparative example has gradually dissipated; according to Table 1, after 7 days, the foams of Examples 1-5 are still stable on the water surface, while the foam in the comparative example disappears. This shows that the addition of tung oil-based emulsifiers can improve the stability of hydrophobic foams. This is because tung oil molecules contain long-chain non-polar hydrocarbon groups, which occupy a large proportion in the molecules, giving tung oil good hydrophobic properties. Tung oil reacts with maleic anhydride, acrylates and other substances to form tung oil anhydride and tung oil anhydride esters. These derivatives retain the hydrophobic properties of tung oil, while introducing new functional groups to enhance the ability to interact with other substances. This feature makes it possible for the foam to be used in paddy fields.

[0057] In order to further test the stability of the hydrophobic foam, taking Example 3 and Comparative Example 1 as examples, the foam was evenly sprayed on the surface of the water-containing soil to observe the stability of the foam at different times. Figure 8 , 9 As shown, the amount of foam gradually decreases with the extension of time. Compared with Comparative Example 1, after one week, the foam in Example 3 still evenly covers the soil surface, while the foam in Comparative Example 1 is significantly reduced, exposing part of the soil and accelerating the evaporation of soil moisture. This is because no tung oil-based emulsifier is added in Comparative Example 1, resulting in a weakened stability of the foam.

[0058] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, 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 hydrophobic foam mulch composition for paddy fields, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of tung oil, 0.5-10 parts of tung oil-based emulsifier, 0.1-1.0 parts of modified nanocellulose fiber, 0.01-0.1 parts of surfactant, and 0.01-0.1 parts of foaming agent; The tung oil-based emulsifier is prepared by reacting tung oil with maleic anhydride via Diels-Alder reaction to form tung oil anhydride, and then reacting the tung oil anhydride with acrylic acid ester and neutralizing the reactant.

2. The composition according to claim 1, characterized in that The molar ratio of the tung oil, maleic anhydride and acrylic ester is 1:(1-5):(1-5).

3. The composition according to claim 2, characterized in that Mix tung oil and maleic anhydride, heat and stir, raise the temperature to 100±10℃ and stir to react for 1±0.2h after the solid is dissolved to obtain tung oil anhydride; add methyl acrylate, catalyst and inhibitor, react at 100±10℃ for 2±0.5h, cool down and add NaOH solution to neutralize to obtain tung oil-based emulsifier.

4. The composition according to claim 3, characterized in that 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 inhibitor is at least one of p-methoxyphenol and hydroquinone, and the amount of the inhibitor is 0.3±0.1% of the total mass of the raw materials; the content of eleostearic acid glyceride in the tung oil is 84±10%.

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

6. The composition according to claim 5, characterized in that The raw material ratio is: 100 parts of tung oil, 3±1 parts of 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; The modified nanocellulose fiber has a diameter of 3-5 nm and a length of 500-1000 nm.

7. The composition according to claim 6, characterized in that The modified nanocellulose fibers are prepared by freeze-drying after nanocellulose gel is blended with high molecular weight polyethylene oxide, wherein the polyethylene oxide accounts for 0.1±0.06wt% of the nanocellulose fibers; The surfactant includes One or more of FS-31, GS-FC829, GS-2478, Span 20 and LutensolTO-3; the foaming agent is KF-F5; the acrylate is one or more of 2-hydroxyethyl methacrylate, hydroxyethyl acrylate and hydroxypropyl methacrylate.

8. Use of the composition according to any one of claims 1 to 7 in the preparation of a hydrophobic foam mulch.

9. The use according to claim 8, characterized in that: Tung oil, tung oil-based emulsifier, modified nanocellulose fiber, surfactant and foaming agent are mixed, stirred at high speed, and carbon dioxide gas is introduced to obtain uniform and stable foam, which is then sprayed to form a hydrophobic foam mulch.

10. The use according to claim 9, characterized in that: The hydrophobic foam mulch film is applied in paddy fields.

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