Water absorption and retention type straw-based biodegradable spraying mulching film and preparation method thereof

Abstract

The invention belongs to the technical field of straw resource utilization and agricultural degradable mulching films, and particularly discloses a water absorption and retention type straw-based biodegradable spraying mulching film and a preparation method thereof.Straw short fibers and biodegradable super absorbent resin are mixed through a V-shaped mixing machine according to a certain proportion, and a homogeneous dry powder formula is prepared; the preparation method comprises the following steps: preparing an adhesive aqueous solution with a certain concentration as a liquid-phase formula, synchronously spraying the dry powder formula and the liquid-phase formula according to a certain ratio by adopting a dry powder sprayer and a water mist spraying can respectively to prepare the continuous and stable mulching film, and preparing the mulching film through simple processes such as crushing, mixing and spraying without complicated equipment. The production cost is obviously lower than that of an existing synthetic polyester / natural polysaccharide mulching film, meanwhile, the problem of environmental pollution caused by straw incineration is solved, the agricultural sustainable development requirement is met, large-scale production is facilitated, the utilization rate of agricultural water resources is increased, and the mulching film has great application potential in arid / semi-arid regions.

Description

Technical Field

[0001] The present invention belongs to the technical fields of straw resource utilization and agricultural degradable mulch films, and specifically discloses a water-absorbing and water-retaining straw-based biodegradable spraying mulch film and a preparation method thereof. Background Technique

[0002] As the core covering technology in modern agriculture, mulch films have functions such as warming, moisturizing, and inhibiting weed growth, which can significantly improve the microenvironment for crop growth and boost grain production. However, more than 90% of the mulch films globally rely on polyethylene for preparation. The stubborn carbon-carbon bonds in its molecular structure make it difficult for the mulch films to degrade in the field, and the long-term accumulation exacerbates the formation risk of microplastics and "white pollution". The Second National Pollution Source Census Bulletin shows that the cumulative residual amount of mulch films in China has reached 1.1848 million tons, which has now caused serious soil pollution problems, such as soil compaction, affecting the absorption of water and fertilizers by crops, and hindering the growth of crop roots.

[0003] In recent years, the research and development of degradable mulch films have attracted much attention in the field of agricultural materials. Its raw material systems can be mainly divided into two categories: synthetic polyesters and natural polysaccharides. However, synthetic polyester-based mulch films such as polylactic acid and polybutylene adipate / terephthalate have poor gas barrier properties and are difficult to construct a dense water barrier layer. Therefore, their water retention performance has not yet reached the requirements of the national general standard GB / T 35795-2017, and polyester materials often require "aerobic composting" to produce degradation behavior; while natural polysaccharide-based mulch films such as starch, cellulose, and chitosan have environmental friendly characteristics, but the hydroxyl groups on their molecular chains are highly sensitive to water, and the mechanical properties of the film deteriorate significantly after encountering water. Therefore, current research on natural polysaccharide mulch films focuses on hydrophobic modification to improve water resistance. In addition, the production cost of degradable mulch films is generally higher than that of traditional plastic mulch films, which restricts their large-scale application in agricultural production. Therefore, it is particularly urgent to develop a new type of degradable mulch film with excellent water retention and cost competitiveness.

[0004] Straw is a high-yield agricultural waste. In 2021, the straw output in China was 802 million tons. In recent years, with the increase in crop straw output and the implementation of the straw burning ban policy, the comprehensive utilization of straw and further improvement of its quality and efficiency have become important issues for sustainable agricultural development. Straw has a significant effect on keeping the temperature and moisture of crops. Compared with existing degradable mulch films, straw-based mulch films have significant advantages in terms of raw material cost and environmental friendliness, and have great potential for large-scale promotion and application. As early as before the 6th century AD, the straw covering technology was recorded in the chapter "Planting Coriander" in Volume 3 of the agricultural classic "Qi Min Yao Shu" in China: "When there is enough frost in October, harvest it. For those who take the seeds, still keep the roots, thin out the plants by pulling them out, and cover them with grass." In addition, straw degradation can effectively increase soil carbon input, improve soil aggregate structure and regulate nutrient balance. However, it is difficult to construct an effective water barrier layer with straw covering, and its water retention performance is difficult to compare with that of existing plastic mulch films. Therefore, it is urgent to develop low-cost improvement technologies to strengthen the water retention performance of straw-based mulch films. Summary of the Invention

[0005] Aiming at the problems of insufficient water retention performance and high production cost of degradable mulch films, the present invention discloses a water-absorbing and water-retaining straw-based biodegradable spray mulch film and its preparation method. Using crop straw as raw material, the straw is cut and blasted by a crusher to prepare straw short fibers, which are mixed with a biodegradable superabsorbent resin, and a continuous and stable mulch film is formed by the solid-liquid synchronous spraying process and the thickening and bonding effect of the binder. On the one hand, the edge fluff of the straw short fibers is effectively used to capture water mist, and on the other hand, water is enriched through the water storage function of the superabsorbent resin, so as to strengthen the water-absorbing and water-retaining performance of the mulch film.

[0006] In order to achieve the above invention purpose, the present invention adopts the following technical solutions: A preparation method of a water-absorbing and water-retaining straw-based biodegradable spray mulch film, comprising the following steps: (1) Put a certain amount of naturally dried straw into a crusher for crushing to obtain straw short fibers through mechanical crushing; (2) Mix the straw short fibers obtained in step (1) with a biodegradable superabsorbent resin in a certain proportion through a V-type mixer to prepare a homogeneous dry powder formula. In addition, prepare an aqueous solution of a binder with a certain concentration as a liquid phase formula; (3) Synchronously spray the dry powder formula and the liquid phase formula obtained in step (2) according to a certain ratio by using a dry powder sprayer and a water mist sprayer respectively to prepare a continuous and stable mulch film.

[0007] Further, in the preparation method of the water-absorbing and water-retaining straw-based biodegradable spray mulch film, the length of the straw short fibers in step (1) is 5-10 mm.

[0008] Further, in the method for preparing the water-absorbing and water-retaining straw-based biodegradable spraying mulch film, the biodegradable superabsorbent resin in step (2) is a graft polymer of natural polysaccharide and acrylic acid and / or a blend composite material of natural polysaccharide and polyacrylic acid.

[0009] Further, in the method for preparing the water-absorbing and water-retaining straw-based biodegradable spraying mulch film, the binder in step (2) is one or a combination of two or more of cold water-soluble α-starch, dextrin, hydroxypropyl starch, sodium carboxymethyl cellulose, sodium alginate, hydroxyethyl cellulose, guar gum, and xanthan gum.

[0010] Further, in the method for preparing the water-absorbing and water-retaining straw-based biodegradable spraying mulch film, the mass ratio of the dry powder formulation to the liquid phase formulation in step (3) is 1 : (1 - 2.5).

[0011] Further, in the method for preparing the water-absorbing and water-retaining straw-based biodegradable spraying mulch film, the natural polysaccharide in step (2) is starch, cellulose, or chitosan.

[0012] Further, in the method for preparing the water-absorbing and water-retaining straw-based biodegradable spraying mulch film, the mass ratio of the straw short fibers to the biodegradable superabsorbent resin in step (2) is 10 : (1 - 3).

[0013] Further, in the method for preparing the water-absorbing and water-retaining straw-based biodegradable spraying mulch film, the concentration of the binder aqueous solution in step (2) is 2 - 10 wt%.

[0014] A water-absorbing and water-retaining straw-based biodegradable spraying mulch film, which uses a large amount of agricultural waste straw as raw material and is prepared by the preparation method described in any one of the above. The mulch film is formed by spraying, and the thickness of the mulch film is 5 - 10 mm.

[0015] Due to the adoption of the above technical solutions, the water-absorbing and water-retaining straw-based biodegradable spraying mulch film and its preparation method of the present invention have the following advantages: (1) For the water-absorbing and water-retaining straw-based biodegradable spraying mulch film disclosed by the present invention, the straw short fibers enhance the water mist capture ability through the edge fluff, and the biodegradable superabsorbent resin realizes efficient water enrichment through the water storage function, enabling the straw fluff to continuously capture water mist. The synergistic effect of the two enables the mulch film to maintain a relatively high water balance in a low-humidity environment, and be able to quickly absorb water and stably retain it in a high-humidity environment, thereby strengthening the water-absorbing and water-retaining performance of the mulch film. Moreover, the mulch film of the present invention uses a spraying process to lay the mulch film, breaking through the defect of the traditional mulch film laying being restricted by the terrain, and is convenient and fast to use; (2) The preparation method of the water-absorbing and water-retaining straw-based biodegradable spraying mulch film disclosed in the present invention mixes straw short fibers and a biodegradable superabsorbent resin in a certain proportion through a V-type mixer to prepare a homogeneous dry powder formula. In addition, an adhesive aqueous solution with a certain concentration is prepared as a liquid phase formula. Then, the dry powder formula and the liquid phase formula are synchronously sprayed according to a certain ratio by a dry powder sprayer and a water mist sprayer respectively, and a continuous and stable mulch film can be prepared. The mulch film is prepared through simple processes such as pulverization, mixing, and spraying, without complex equipment. The production cost is significantly lower than that of existing synthetic polyester / natural polysaccharide mulch films. At the same time, it solves the environmental pollution problem caused by straw burning, meets the requirements of agricultural sustainable development, is convenient for mass production, and improves the utilization rate of agricultural water resources, and has great application potential in arid / semi-arid regions; (3) The preparation method of the water-absorbing and water-retaining straw-based biodegradable spraying mulch film disclosed in the present invention uses raw materials that are all biodegradable materials. The prepared mulch film has the characteristics of complete biodegradation, avoiding the "white pollution" and microplastic residue problems caused by traditional polyethylene mulch films. The degradation products can improve the soil structure, such as increasing carbon input and regulating nutrient balance. Brief Description of the Drawings

[0016] Figure 1 is a comparison diagram of the formed mulch films in Example 1 and the comparative example of the present invention; Figure 2 is a comparison diagram of the states of the formed mulch films in Example 1 and the comparative example of the present invention after water absorption; Figure 3 is a comparison diagram of the mass change curve of the formed mulch films in Example 1 and the comparative example of the present invention at 25 °C and different humidities. Detailed Embodiments

[0017] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The present invention is not limited to the following embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present invention. In addition, the reagents in the present invention are all commercially available conventional reagents unless otherwise specified, and the methods are all conventional methods unless otherwise specified. Example 1

[0018] (1) Load 1 kg of naturally dried straw into a pulverizer, and obtain straw short fibers through mechanical pulverization. The rotation speed of the pulverizer is 2000 rpm, and the processing time is 12 min. The length of the straw short fibers is concentrated in 5-10 mm; (2) Mix the straw short fibers obtained in step (1) with the starch-grafted polyacrylic acid biodegradable superabsorbent resin in a mass ratio of 10:2 in a V-type mixer for 15 minutes to prepare a homogeneous dry powder formulation; prepare an α-starch aqueous solution with a concentration of 4 wt% as the liquid phase formulation; (3) Synchronously spray the dry powder formulation and the liquid phase formulation obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively in a mass ratio of 1:1.5 to prepare a continuous and stable plastic film. After spraying and forming, the thickness of the plastic film is 5 - 10 mm.

[0019] The comparison diagrams of the formed plastic films in Example 1 and the comparative example are as Figure 1 shown, and the comparison diagrams of the states of the formed plastic films in Example 1 and the comparative example after water absorption are as Figure 2 shown, and the comparison diagrams of the mass change curves of the formed plastic films in Example 1 and the comparative example at 25 °C and different humidities are as Figure 3 shown. Example 2

[0020] (1) Load 1 kg of naturally dried straw into a pulverizer, and obtain straw short fibers through mechanical pulverization. The rotational speed of the pulverizer is 2000 rpm, and the processing time is 12 minutes. The length of the straw short fibers is concentrated in the range of 5 - 10 mm; (2) Mix the straw short fibers obtained in step (1) with the cellulose-grafted polyacrylic acid biodegradable superabsorbent resin in a mass ratio of 10:3 in a V-type mixer for 15 minutes to prepare a homogeneous dry powder formulation; prepare a dextrin aqueous solution with a concentration of 10 wt% as the liquid phase formulation; (3) Synchronously spray the dry powder formulation and the liquid phase formulation obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively in a mass ratio of 1:2.5 to prepare a continuous and stable plastic film. After spraying and forming, the thickness of the plastic film is 5 - 10 mm. Example 3

[0021] (1) Load 1 kg of naturally dried straw into a pulverizer, and obtain straw short fibers through mechanical pulverization. The rotational speed of the pulverizer is 2000 rpm, and the processing time is 12 minutes. The length of the straw short fibers is concentrated in the range of 5 - 10 mm; (2) Mix the starch-grafted polyacrylic acid and cellulose-grafted polyacrylic acid in a mass ratio of 1:1 to obtain a biodegradable superabsorbent resin. Mix the straw short fibers obtained in step (1) with this biodegradable superabsorbent resin in a mass ratio of 10:2.5 in a V-type mixer for 15 minutes to prepare a homogeneous dry powder formulation; prepare a hydroxypropyl starch aqueous solution with a concentration of 3 wt% as the liquid phase formulation; (3) Synchronously spray the dry powder formula and the liquid phase formula obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively according to a mass ratio of 1:1.25 to prepare a continuous and stable ground film. After spraying and forming, the thickness of the ground film is 5 - 10 mm. Example 4

[0022] (1) Load 1 kg of naturally dried straw into a pulverizer and obtain straw short fibers through mechanical pulverization. The rotation speed of the pulverizer is 2000 rpm, the processing time is 12 min, and the length of the straw short fibers is concentrated in the range of 5 - 10 mm. (2) Mix the straw short fibers obtained in step (1) with a biodegradable superabsorbent resin of chitosan grafted polyacrylic acid in a mass ratio of 10:1 in a V-type mixer for 15 min to prepare a homogeneous dry powder formula; configure an aqueous sodium alginate solution with a concentration of 2 wt% as the liquid phase formula. (3) Synchronously spray the dry powder formula and the liquid phase formula obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively according to a mass ratio of 1:1 to prepare a continuous and stable ground film. After spraying and forming, the thickness of the ground film is 5 - 10 mm. Example 5

[0023] (1) Load 1 kg of naturally dried straw into a pulverizer and obtain straw short fibers through mechanical pulverization. The rotation speed of the pulverizer is 2000 rpm, the processing time is 12 min, and the length of the straw short fibers is concentrated in the range of 5 - 10 mm. (2) Mix the straw short fibers obtained in step (1) with a blend composite material of starch and polyacrylic acid in a mass ratio of 10:3 in a V-type mixer for 15 min to prepare a homogeneous dry powder formula; configure an aqueous solution of hydroxyethyl cellulose with a concentration of 5 wt% as the liquid phase formula. (3) Synchronously spray the dry powder formula and the liquid phase formula obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively according to a mass ratio of 1:2.25 to prepare a continuous and stable ground film. After spraying and forming, the thickness of the ground film is 5 - 10 mm. Example 6

[0024] (1) Load 1 kg of naturally dried straw into a pulverizer and obtain straw short fibers through mechanical pulverization. The rotation speed of the pulverizer is 2000 rpm, the processing time is 12 min, and the length of the straw short fibers is concentrated in the range of 5 - 10 mm. (2) Mix the straw short fibers obtained in step (1) with a blend composite material of cellulose and polyacrylic acid in a mass ratio of 10:2 in a V-type mixer for 15 min to prepare a homogeneous dry powder formula; configure an aqueous solution of guar gum with a concentration of 2 wt% as the liquid phase formula. (3) Synchronously spray the dry powder formula and the liquid phase formula obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively according to a mass ratio of 1:1 to prepare a continuous and stable plastic film. After spraying and forming, the thickness of the plastic film is 5 - 10 mm. Example 7

[0025] (1) Load 1 kg of naturally sun-dried straw into a pulverizer, and obtain straw short fibers through mechanical pulverization. The rotation speed of the pulverizer is 2000 rpm, and the processing time is 12 min. The length of the straw short fibers is concentrated in the range of 5 - 10 mm; (2) Mix the straw short fibers obtained in step (1) with a blend composite material of chitosan and polyacrylic acid according to a mass ratio of 10:1.5, and mix in a V-type mixer for 15 min to prepare a homogeneous dry powder formula; configure an aqueous xanthan gum solution with a concentration of 2.5 wt% as the liquid phase formula; (3) Synchronously spray the dry powder formula and the liquid phase formula obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively according to a mass ratio of 1:1 to prepare a continuous and stable plastic film. After spraying and forming, the thickness of the plastic film is 5 - 10 mm. Example 8

[0026] (1) Load 1 kg of naturally sun-dried straw into a pulverizer, and obtain straw short fibers through mechanical pulverization. The rotation speed of the pulverizer is 2000 rpm, and the processing time is 12 min. The length of the straw short fibers is concentrated in the range of 5 - 10 mm; (2) Mix two biodegradable superabsorbent resins, starch-grafted polyacrylic acid and chitosan-grafted polyacrylic acid, according to a mass ratio of 1:1, and mix the straw short fibers obtained in step (1) with this mixed superabsorbent resin according to a mass ratio of 10:1.75, and mix in a V-type mixer for 15 min to prepare a homogeneous dry powder formula; configure an aqueous blend solution of α-starch and carrageenan with a concentration of 2.5 wt% as the liquid phase formula, and the mass ratio of α-starch to carrageenan in the aqueous blend solution of α-starch and carrageenan is 3:1; (3) Synchronously spray the dry powder formula and the liquid phase formula obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively according to a mass ratio of 1:1.5 to prepare a continuous and stable plastic film. After spraying and forming, the thickness of the plastic film is 5 - 10 mm. Example 9

[0027] (1) Load 1 kg of naturally sun-dried straw into a pulverizer, and obtain straw short fibers through mechanical pulverization. The rotation speed of the pulverizer is 2000 rpm, and the processing time is 12 min. The length of the straw short fibers is concentrated in the range of 5 - 10 mm; (2) Mix the straw short fibers obtained in step (1) with the starch-grafted polyacrylic acid biodegradable superabsorbent resin at a mass ratio of 10:2 in a V-type mixer for 15 min to prepare a homogeneous dry powder formulation; prepare a liquid-phase formulation by configuring an aqueous blend solution of α-starch and carrageenan with a concentration of 4 wt%, and the mass ratio of α-starch to carrageenan in the aqueous blend solution of α-starch and carrageenan is 3:1; (3) Synchronously spray the dry powder formulation and the liquid-phase formulation obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively at a mass ratio of 1:1 to prepare a continuous and stable plastic film, and the thickness of the plastic film after spraying and forming is 5 - 10 mm. Example 10

[0028] (1) Load 1 kg of naturally dried straw into a crusher, and obtain straw short fibers through mechanical crushing. The rotation speed of the crusher is 2000 rpm, the processing time is 12 min, and the length of the straw short fibers is concentrated in the range of 5 - 10 mm; (2) Mix the straw short fibers obtained in step (1) with the starch-grafted polyacrylic acid biodegradable superabsorbent resin at a mass ratio of 10:2 in a V-type mixer for 15 min to prepare a homogeneous dry powder formulation; prepare a liquid-phase formulation by configuring an aqueous blend solution of dextrin and sodium alginate with a concentration of 8 wt%, and the mass ratio of dextrin to sodium alginate in the aqueous blend solution of dextrin and sodium alginate is 7:1; (3) Synchronously spray the dry powder formulation and the liquid-phase formulation obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively at a mass ratio of 1:1.5 to prepare a continuous and stable plastic film, and the thickness of the plastic film after spraying and forming is 5 - 10 mm. Example 11

[0029] (1) Load 1 kg of naturally dried straw into a crusher, and obtain straw short fibers through mechanical crushing. The rotation speed of the crusher is 2000 rpm, the processing time is 12 min, and the length of the straw short fibers is concentrated in the range of 5 - 10 mm; (2) Mix the straw short fibers obtained in step (1) with the starch-grafted polyacrylic acid biodegradable superabsorbent resin at a mass ratio of 10:2 in a V-type mixer for 15 min to prepare a homogeneous dry powder formulation; prepare a liquid-phase formulation by configuring an aqueous blend solution of dextrin and hydroxyethyl cellulose with a concentration of 7 wt%, and the mass ratio of dextrin to hydroxyethyl cellulose in the aqueous blend solution of dextrin and hydroxyethyl cellulose is 2.5:1; (3) Synchronously spray the dry powder formulation and the liquid-phase formulation obtained in step (2) using a dry powder sprayer and a water mist sprayer respectively at a mass ratio of 1:3 to prepare a continuous and stable plastic film, and the thickness of the plastic film after spraying and forming is 5 - 10 mm.

[0030] Comparative Example (1) 1 kg of naturally dried straw was loaded into a pulverizer and mechanically pulverized to obtain straw short fibers. The rotational speed of the pulverizer was 2000 rpm, and the processing time was 12 min. The length of the straw short fibers was concentrated in the range of 5 - 10 mm; (2) Without adding a biodegradable superabsorbent resin, the straw short fibers obtained in step (1) were directly used as the dry powder formulation; an α - starch aqueous solution with a concentration of 4 wt% was prepared as the liquid phase formulation; (3) The dry powder formulation and the liquid phase formulation obtained in step (2) were synchronously sprayed using a dry powder sprayer and a water mist sprayer respectively according to a mass ratio of 1:1.5 to prepare a continuous and stable plastic film. After spraying and forming, the thickness of the plastic film was 5 - 10 mm.

[0031] The comparison diagrams of the formed plastic films in Example 1 and the Comparative Example are as Figure 1 shown. The comparison diagrams of the states of the formed plastic films in Example 1 and the Comparative Example after water absorption are as Figure 2 shown, Figure 1 and Figure 2 in which 2 cm is the scale. The comparison diagrams of the mass change curves of the formed plastic films in Example 1 and the Comparative Example at 25 °C and different humidities are as Figure 3 shown.

[0032] The water absorption test was carried out on the water - absorbing and water - retaining straw - based biodegradable sprayed plastic films prepared in Examples 1 - 11 and the Comparative Example using the relative humidity method, and the mass change of the plastic films within 24 h was observed. A saturated solution of sodium chloride was prepared, and the temperature was controlled at 25 °C and the relative humidity at 57.57% using a thermostatic chamber. The formed plastic films were placed in the above - mentioned environment, and the plastic films were weighed every 8 h to calculate the mass change; after the water absorption test experiment was completed, the plastic films were watered, and it was observed whether the plastic films could maintain stability after sufficient water absorption. The mass change of the plastic films and the forming situation after watering are listed in Table 1 below.

[0033] Table 1 Mass change of the plastic film and forming situation after watering Combined with Table 1 and the experimental data in Figure 3 it can be seen that when the water - absorbing and water - retaining straw - based biodegradable sprayed plastic films prepared in Examples 1 - 11 were subjected to the water absorption test, under different humidity conditions and when placed open - mouthed, the mass of the plastic films increased significantly with the extension of time, and the growth rate was significantly higher than that of the plastic films in the Comparative Example, indicating that the plastic films of the present invention can still maintain a high water balance in a low - humidity environment, and can quickly absorb water and stably retain it in a high - humidity environment, thereby enhancing the water - absorbing and water - retaining performance of the plastic films.

[0034] The water-absorbing and water-retaining straw-based biodegradable spraying mulch film of the present invention and its preparation method realize the preparation of the mulch film through simple processes such as pulverization, mixing, and spraying, without complex equipment, and the production cost is significantly lower than that of existing synthetic polyester / natural polysaccharide mulch films. This product has great application potential as an agricultural mulch film in arid / semi-arid regions.

[0035] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a water-absorbing and water-retaining straw-based biodegradable sprayable mulch film, characterized in that: The steps include: (1) A certain amount of naturally dried straw is put into a crusher for crushing, and straw short fibers are obtained through mechanical crushing; (2) The short straw fibers obtained in step (1) are mixed with a biodegradable super absorbent resin in a certain ratio by a V-type mixer to prepare a homogeneous dry powder formula, and a certain concentration of an adhesive aqueous solution is prepared as a liquid phase formula; (3) The dry powder formula and the liquid formula obtained in step (2) are sprayed synchronously in a certain ratio using a dry powder sprayer and a water mist spray pot respectively to prepare a continuous and stable ground film.

2. The method for preparing the water-absorbing and water-retaining straw-based biodegradable sprayable mulch film according to claim 1, characterized in that: The length of the straw short fibers in step (1) is 5 to 10 mm.

3. The method for preparing the water-absorbing and water-retaining straw-based biodegradable sprayable mulch film according to claim 1, characterized in that: The biodegradable super absorbent resin in step (2) is a grafted polymer of natural polysaccharide and acrylic acid and / or a blended composite material of natural polysaccharide and polyacrylic acid.

4. The method for preparing the water-absorbing and water-retaining straw-based biodegradable sprayable mulch film according to claim 1, characterized in that: The adhesive in step (2) is one or a combination of two or more of cold water-soluble α-starch, dextrin, hydroxypropyl starch, sodium carboxymethyl cellulose, sodium alginate, hydroxyethyl cellulose, guar gum, and xanthan gum.

5. The method for preparing the water-absorbing and water-retaining straw-based biodegradable sprayable mulch film according to claim 1, characterized in that: The mass ratio of the dry powder formula to the liquid phase formula in step (3) is 1: (1-2.5).

6. The method for preparing the water-absorbing and water-retaining straw-based biodegradable sprayable mulch film according to claim 3, characterized in that: In step (2), the natural polysaccharide is starch, cellulose or chitosan.

7. The method for preparing the water-absorbing and water-retaining straw-based biodegradable sprayable mulch film according to claim 3, characterized in that: In step (2), the mass ratio of the straw short fibers to the biodegradable super absorbent resin is 10:(1-3).

8. The method for preparing the water-absorbing and water-retaining straw-based biodegradable sprayable mulch film according to claim 4, characterized in that: The concentration of the binder aqueous solution in step (2) is 2-10 wt%.

9. A water-absorbing and water-retaining straw-based biodegradable sprayable mulch film, characterized in that: The ground film is prepared by the preparation method according to any one of claims 1 to 8.

10. A water-absorbing and water-retaining straw-based biodegradable sprayable mulch film, characterized in that: The ground film is formed by spraying, and the thickness of the ground film is 5-10 mm.

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