Broad-spectrum anti-reverse agricultural and forestry water-retaining agent and preparation method thereof

Abstract

The application discloses a broad-spectrum anti-reverse agricultural and forestry water-retaining agent and a preparation method thereof, relates to the technical field of water gel water-retaining agent preparation, and comprises the following components in parts by weight: acrylic acid, a pH regulator, a skeleton supporting agent, a charge regulator, a thickening agent spacing regulator, an initiator and water; the skeleton supporting agent and the thickening agent are used as inert supports of a three-dimensional network of a gel, a stimulus-responsive passivation region is formed, polyacrylic acid is used as a main chain, a buffer region is formed by controlling the balance of carboxylate and carboxyl through the action of the pH regulator, cationic monomers or zwitterionic monomers containing an acrylic acid derivative molecular structure are used as the charge regulator, the proportion of positive and negative charges in a molecular network is regulated, the water-retaining agent can respectively exhibit the response properties of polyanion, polycation or polyamphoteric ion to different environmental stimuli, and the water-retaining agent has the properties of resistance to various types of salt, a large salt concentration interval, resistance to alkali, resistance to acid, resistance to chemical fertilizer and resistance to heavy metal ions.

Description

Technical Field

[0001] This invention relates to the field of hydrogel water-retaining agent preparation technology, and in particular to a broad-spectrum stress-resistant agricultural and forestry water-retaining agent and its preparation method. Background Technology

[0002] Agricultural and forestry water-retaining agents are a class of polymeric materials with a three-dimensional network structure. With excellent water absorption, storage, and slow release properties, they are suitable for arid soil environments and belong to a new type of agricultural soil improvement and water-saving drought-resistant material. These substances can efficiently adsorb and retain soil moisture, enhance soil water retention capacity, reduce water evaporation and seepage, and achieve water conservation and efficiency in agriculture. At the same time, they can also slowly release nutrients such as nitrogen, phosphorus, and potassium, improve fertilizer utilization, reduce environmental pollution caused by fertilizer runoff, improve soil aggregate structure, alleviate soil compaction, and effectively enhance the drought resistance and stress resistance of crops and seedlings. They have important applications in agriculture, forestry, horticulture, desertification control and ecological restoration, and island greening.

[0003] Commercial agricultural and forestry water-retaining agents are mainly polyacrylic acid-based, belonging to the category of anionic hydrogels. They have advantages such as wide availability, low cost, and high water absorption rate, but also have serious drawbacks: they have a strong irritant response to acids, alkalis, and salts in the environment, and their water-retaining performance decreases sharply or even fails.

[0004] Research on the environmental adaptability of polyacrylic acid-based water-retaining agents for agriculture and forestry often employs methods such as adding inert raw materials, modifying with salt- and alkali-tolerant microorganisms, and adding sulfonic acid monomers or betaine monomers to enhance salt resistance. However, these products generally suffer from problems such as limited salt tolerance, narrow salt concentration range, poor acid and alkali adaptability, low compatibility with chemical fertilizers, and easy inactivation upon contact with heavy metal ions.

[0005] Polyacrylic acid-based water-retaining agents for agriculture and forestry obtained by conventional preparation methods do not possess broad-spectrum stress resistance properties (i.e., simultaneously possessing resistance to multiple types of salts, a wide range of salt concentrations, alkali resistance, acid resistance, fertilizer resistance, and heavy metal ion resistance).

[0006] In the prior art, patent application CN1699508A (2005) relates to a method for preparing a salt-alkali resistant multifunctional water-retaining agent, using the inorganic mineral attapulgite to improve salt and alkali resistance, and testing the water absorption rate to physiological saline and 0.5% calcium-magnesium solution. Patent application CN103374093A (2012) relates to a method for preparing a betaine-type antibacterial superabsorbent resin, using betaine monomer as a raw material to improve salt resistance, and testing the water absorption rate to physiological saline at 52-107 g / g. Patent application CN103030913A (2015) relates to a method for preparing a quaternary ammonium salt composite self-absorbing agent, adding quaternary ammonium salt as the main raw material, for use in drought resistance in agriculture and forestry. Patent application CN106496410A (2016) relates to an anti-seepage agent, using inorganic fillers such as ultrafine calcium carbonate or bentonite to provide skeletal support. Patent application CN106365887A (2017) relates to a method for preparing a salt-alkali tolerant fertilizer-type water-retaining agent, which uses salt-alkali tolerant plant leaves for modification and tests the absorption multiple of sodium carbonate brine at pH 9. Patent application CN108329422A (2018) relates to a water-in-water microsphere profile control agent, which uses sodium hydroxide to adjust the pH to 6.0–6.5 and uses anionic or nonionic polymers as charge regulators. Patent application CN110372886A (2019) relates to a method for preparing a chitosan-polysulfonic acid-based betaine dual-network self-healing hydrogel, the prepared product possessing mechanical strength and self-healing properties. Patent application CN115259942A (2022) discloses a method for preparing a polymeric salt-tolerant and water-retaining fertilizer. It uses biochar, sulfonic acid monomers, and other raw materials mixed with chemical fertilizers, and tests the effect on corn cultivation in soil with a pH of 8.16. Patent application CN116925279A (2023) discloses a salt-tolerant and water-retaining agent and its preparation method. It uses a synthesized salt-tolerant monomer as a raw material, introduces amide groups that are insensitive to salt and sulfonic acid groups with strong dissociation ability, and tests the absorption effect on physiological saline. Patent application CN116515022A (2023) discloses a method for preparing a ureosulfobetaine zwitterionic hydrogel, and tests the mechanical strength of the product. Patent application CN106365887A (2024) discloses a method for preparing a functional water-retaining agent for saline-alkali farmland, using polyacrylamide and fermented bio-organic raw materials, and evaluating its effectiveness in soil with a salt content of 0.32% and a pH of 7.46. In summary, the prior art has not yet provided a technical solution to the above and related problems. Summary of the Invention

[0007] This invention aims to provide a broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops and its preparation method. A skeletal support agent and a thickener serve as inert supports for a three-dimensional gel network, forming a stimulus-response passivation region. Polyacrylic acid is used as the main chain, and a pH adjuster controls the balance between carboxyl and carboxyl groups to form a buffer region. Cationic or zwitterionic monomers containing acrylic acid derivative molecular structures are used as charge regulators to precisely control the ratio of positive to negative charges in the molecular network. The resulting charge effect enables the broad-spectrum stress-resistant water-retaining agent to exhibit polyanionic, polycationic, or polyzwitterionic responsive properties to different environmental stimuli, i.e., self-adaptability. A spacing regulator controls the mesh size of the microscopic three-dimensional network, further regulating its water absorption and swelling properties.

[0008] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops comprises the following components by weight: 100 parts acrylic acid, 5 to 20 parts pH adjuster, 50 to 200 parts skeleton support agent, 20 to 100 parts charge adjuster, 10 to 20 parts thickener, 0.2 to 0.5 parts spacing adjuster, 1 to 20 parts initiator, and 500 to 2000 parts water; The skeletal support is an electrically neutral compound containing hydroxyl active groups; The charge regulator is a cationic monomer or a zwitterionic monomer containing an acrylic acid derivative molecular structure. The spacing adjuster is a multi-functional compound or oligomer; The pH adjuster is an alkali metal phosphate or an alkaline earth metal phosphate. The thickener is a polymer formed by the dehydration condensation of α-D-glucose structural units; The initiator is a composite initiation system composed of vanadium oxalate and sodium persulfate.

[0009] The pH adjuster is sodium tripolyphosphate; The electrically neutral compound can be graft copolymerized, has a molecular weight of <200 g / mol, and is amphiphilic and lipophilic, and is soluble in water, ethanol or acetone. The skeleton support agent is 4-hydroxybutyl acrylate; The charge regulator is soluble in water; The charge regulator is N-(2-acryloyloxyethyl)-N-benzyl-N,N-dimethylammonium chloride; The thickener is glycogen; The spacing regulator has a molecular weight of 140 g / mol to 1200 g / mol, and the spacing regulator can be grafted copolymerized with hydroxyl groups or carbon-carbon double bonds. The spacing adjuster is 1,4-hydroxybutylacrylate glycidyl ether; The mass ratio of vanadium oxalate to sodium persulfate is 1:5 to 1:20. A method for preparing a broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops includes the following steps: S1. Mix acrylic acid, pH adjuster, skeleton support agent, charge adjuster, thickener, spacing adjuster and water at 60℃~80℃, stir in a closed container for 20~50 minutes, and then cool to room temperature to obtain a mixed system; S2. Add the initiator to the mixing system, stir to dissolve, pour into a mold, seal with nitrogen, keep at 50℃~85℃ for 1~3 hours, remove, let stand at room temperature for 6~12 hours, demold, dry and pulverize at 50~80℃, and pass through a 100~200 mesh sieve to obtain the broad-spectrum stress-resistant agricultural and forestry water-retaining agent.

[0010] The beneficial effects of this invention are: 1. In this invention, to achieve a high water absorption and swelling rate in fresh water, acrylic acid is used as a raw material. The polyelectrolyte effect of anionic polymers, specifically the repulsive force between the carboxyl groups (-COOH) and the dissociated carboxylate ions (-COO-), expands the molecular network region. The acrylic acid raw material generates a polyelectrolyte effect; in fresh water, the carboxyl groups (-COOH) dissociate into carboxylate ions (-COO-), causing the molecular network region to expand due to the repulsive force between them, resulting in a high water absorption and swelling rate (SR) of the hydrogel. When environmental stimuli (acids, alkalis, salts, fertilizers) are present, some carboxylate ions are shielded by free ions, and the repulsive force is canceled out, gradually reducing the contribution of acrylic acid to the SR. In other words, acrylic acid provides the main support for the SR in fresh water.

[0011] 2. In this invention, to achieve a high salinity (SR) in salt water, cationic or zwitterionic monomers are used as raw materials. These monomers react with carboxyl / carboxylate groups to produce an anti-polyelectrolyte effect, promoting the increase of water absorption and swelling rate in areas with high salt concentration. Simultaneously, the relatively excess anions / cations exhibit a polyelectrolyte effect of polycations or polyanions. The synergistic effect of these two opposing factors produces a charge regulation effect, causing the overall water absorption and swelling rate of the water-retaining agent to increase or decrease with environmental stimuli, thus achieving a designable and controllable SR. The raw material charge regulator produces an anti-polyelectrolyte effect and charge regulation function. The presence of cationic or zwitterionic monomer raw materials can introduce a certain amount of cationic groups, which pair with -COO- due to the attraction of opposite charges, producing an anti-polyelectrolyte effect and giving the hydrogel a certain degree of salt resistance. The relatively excess cations or carboxyl groups exhibit a simple polycation or polyanion response to environmental stimuli, forming a charge regulation effect. The superposition of these two opposing factors produces a synergistic effect, giving the broad-spectrum stress-resistant agricultural and forestry water-retaining agent a certain degree of environmental stimuli adaptability. In other words, charge regulators provide the main support for SR in saline environments.

[0012] 3. In this invention, to ensure that the water-retaining agent exhibits a relatively small fluctuation range in water absorption and swelling rate across a wide range of ion concentrations and environmental stimuli, a framework support, a thickener, and a pH adjuster are employed. Through synergistic action, these components create a swelling kinetic control effect, forming a microscopic passivation and buffer network region. This alleviates the severe local three-dimensional network contraction / expansion caused by the polyelectrolyte effect and charge effect, thereby reducing the response rate of the water-retaining agent to environmental stimuli. The framework support participates in the copolymerization process, forming a passivation region in response to environmental stimuli, mitigating the severe local three-dimensional network contraction / expansion caused by the synergistic effect of the polyelectrolyte effect and charge effect, thus maintaining relative stability of the SR (swelling rate) of the hydrogel when exposed to salt or fertilizer. The thickener participates in the copolymerization process, enhancing the mass transfer resistance within the three-dimensional network, further passivating the salt-sensitive response. The pH adjuster forms a buffer solution region, reducing the water-retaining agent's response to pH stimulation. The combined effect of these related factors makes the hydrogel adaptable to various extreme environmental stimuli.

[0013] 4. In this invention, to adjust the size of the three-dimensional network of the water-retaining agent molecules to a suitable level, while taking into account both a high water absorption and swelling rate and a low degree of response to environmental stimuli, and simultaneously possessing cross-linking and molecular chain spacing adjustment functions, the spacing regulator is a multi-functional compound or oligomer with a molecular weight of 140 g / mol to 1200 g / mol, which can be grafted and copolymerized with hydroxyl groups or carbon-carbon double bonds. The spacing regulator participates in the copolymerization process and possesses cross-linking and molecular chain spacing adjustment functions, thereby keeping the size of the three-dimensional network of the hydrogel molecules suitable, which helps to accurately design and control the effect of SR, and gives the hydrogel a certain mechanical strength.

[0014] 5. Compared with water-retaining agents prepared by conventional methods, the broad-spectrum stress-resistant agricultural and forestry water-retaining agent of this invention has an adjustable freshwater swelling rate (200g / g~2500g / g, designable with an error ≤50g / g) and a broad-spectrum stress-resistant effect. It exhibits good adaptability to harsh environments such as pH 2~11, 0.1%~20% NaCl, 0.1%~10% CaCl2 / MgCl2, 0.1%~10% ammonium bicarbonate / KCl / K2SO4, 0.1%~5% KH2PO4 / K2HPO4 / K3PO4, and mixed saline solutions (10% NaCl+2% KCl+2% CaCl2+2% MgCl2). It also has good adaptability to Cu2+ in soil. + It features improved adsorption and passivation effects for heavy metals. The synergistic effect of multiple raw materials gives this broad-spectrum stress-resistant agricultural and forestry water-retaining agent adjustable freshwater swelling ratio and broad-spectrum stress resistance, maintaining a high SR (Solubility Saturation) in various environments such as acid, alkali, salinity, and fertilizer. Furthermore, due to its large content of acidic and basic groups, it possesses the ability to adsorb and fix Cu in the soil. 2+ It contains heavy metal ions and improves the soil microenvironment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the working principle of the broad-spectrum stress-resistant water-retaining agent for agriculture and forestry of the present invention.

[0016] Figure 2 The infrared spectrum of the broad-spectrum stress-resistant water-retaining agent for agriculture and forestry of the present invention is shown.

[0017] Figure 3 This is a schematic diagram illustrating the swelling properties of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops of the present invention in fresh water and its reversible response properties in NaCl brine.

[0018] Figure 4 This is a schematic diagram illustrating the swelling properties of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops of the present invention in salt water or fertilizer solutions.

[0019] Figure 5 This is a schematic diagram showing the swelling performance of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops under different pH conditions.

[0020] Figure 6 This is an environmental scanning electron microscope image of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops of the present invention after swelling in mixed salt water.

[0021] Figure 7 This is an environmental scanning electron microscope image of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops of the present invention after swelling in 10% CuSO4 saline solution.

[0022] Figure 8 The broad-spectrum stress-resistant water-retaining agent of the present invention adsorbs Cu 2+ Characterization diagram of saturated X-ray synchrotron radiation.

[0023] Figure 9 This diagram illustrates the experimental performance of the broad-spectrum stress-resistant water-retaining agent of the present invention on the drought resistance of mung bean sprouts under water shortage stress. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0025] Example 1 This embodiment provides a broad-spectrum stress-resistant water-retaining agent for agricultural and forestry industries. The preparation method of this broad-spectrum stress-resistant water-retaining agent includes the following steps: S1. Mix 100 parts of acrylic acid, 20 parts of sodium tripolyphosphate, 50 parts of 4-hydroxybutyl acrylate, 100 parts of N-(2-acryloyloxyethyl)-N-benzyl-N,N-dimethylammonium chloride, 10 parts of glycogen, 0.2 parts of 1,4-hydroxybutyl acrylate glycidyl ether, and 2000 parts of water at 60°C, stir under closed container for 30 minutes, and then cool to room temperature to obtain a mixed system. S2. Add 5 parts of vanadium oxalate and sodium persulfate (mass ratio 1:8) to the mixture, stir to dissolve, pour into a mold, seal with nitrogen, keep at 60℃ for 60 minutes, remove, let stand at room temperature for 12 hours, demold, dry and pulverize at 60℃, and pass through a 100-mesh sieve to obtain the broad-spectrum stress-resistant agricultural and forestry water-retaining agent with a yield of 99.2% and a freshwater swelling rate of 2500 g / g.

[0026] Example 2 In this embodiment, the preparation method of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry includes the following steps: S1. Mix 100 parts of acrylic acid, 5 parts of sodium tripolyphosphate, 200 parts of 4-hydroxybutyl acrylate, 20 parts of N-(2-acryloyloxyethyl)-N-benzyl-N,N-dimethylammonium chloride, 20 parts of glycogen, 0.5 parts of 1,4-hydroxybutyl acrylate glycidyl ether, and 500 parts of water at 80°C, stir under closed container for 20 minutes, and then cool to room temperature to obtain a mixed system. S2. Add 20 parts of vanadium oxalate and sodium persulfate (mass ratio 1:15) to the mixture, stir to dissolve, pour into a mold, seal with nitrogen, keep at 80°C for 2 hours, remove, let stand at room temperature for 8 hours, demold, dry and pulverize at 80°C, and pass through a 100-mesh sieve to obtain the broad-spectrum stress-resistant agricultural and forestry water-retaining agent with a yield of 99.7% and a freshwater swelling rate of 200 g / g.

[0027] Example 3 S1. Mix 100 parts of acrylic acid, 15 parts of sodium tripolyphosphate, 120 parts of 4-hydroxybutyl acrylate, 60 parts of N-(2-acryloyloxyethyl)-N-benzyl-N,N-dimethylammonium chloride, 14 parts of glycogen, 0.3 parts of 1,4-hydroxybutyl acrylate glycidyl ether, and 1500 parts of water at 65°C, stir under closed-loop control for 35 minutes, and then cool to room temperature to obtain a mixed system. S2. Add 15 parts of vanadium oxalate and sodium persulfate (mass ratio 1:12) to the mixture, stir to dissolve, pour into a mold, seal with nitrogen, keep at 70°C for 3 hours, remove, let stand at room temperature for 12 hours, demold, dry and pulverize at 65°C, and pass through a 200-mesh sieve to obtain the broad-spectrum stress-resistant agricultural and forestry water-retaining agent with a yield of 98.7% and a freshwater swelling rate of 1200 g / g.

[0028] Example 4 S1. Mix 100 parts of acrylic acid, 5 parts of sodium tripolyphosphate, 150 parts of 4-hydroxybutyl acrylate, 70 parts of N-(2-acryloyloxyethyl)-N-benzyl-N,N-dimethylammonium chloride, 16 parts of glycogen, 0.4 parts of 1,4-hydroxybutyl acrylate glycidyl ether, and 800 parts of water at 75°C. Stir in a sealed container for 45 minutes, then cool to room temperature to obtain the mixed system. S2. Add 18 parts of vanadium oxalate and sodium persulfate (mass ratio 1:20) to the mixture, stir to dissolve, pour into a mold, seal with nitrogen, keep at 85℃ for 90 minutes, remove, let stand at room temperature for 10 hours, demold, dry and pulverize at 80℃, and pass through a 200-mesh sieve to obtain the broad-spectrum stress-resistant agricultural and forestry water-retaining agent with a yield of 98.3% and a freshwater swelling rate of 870 g / g.

[0029] The molecular structure design principle of the broad-spectrum stress-resistant water-retaining agent for agriculture and forestry in this invention is as follows: A framework support and thickener serve as inert supports for the three-dimensional gel network, forming a stimulus-response passivation region; polyacrylic acid is used as the main chain, and a pH adjuster controls the balance between carboxyl and carboxyl groups to form a buffer region; cationic or zwitterionic monomers containing acrylic acid derivative molecular structures are used as charge regulators to precisely control the ratio of positive and negative charges in the molecular network. The resulting charge effect enables the broad-spectrum stress-resistant water-retaining agent for agriculture and forestry to exhibit polyanionic, polycationic, or polyzwitterionic response properties to different environmental stimuli, i.e., self-adaptability; a spacing regulator controls the mesh size of the microscopic three-dimensional network, further regulating water absorption and swelling performance. The synergistic effect of multiple effects gives the broad-spectrum stress-resistant water-retaining agent adjustable freshwater swelling ratio and broad-spectrum stress resistance. Furthermore, due to its structural advantages, it also possesses the ability to adsorb and fix Cu in the soil. 2+ It has the effect of removing heavy metal ions and improving the soil microenvironment. The working principle of the broad-spectrum stress-resistant water-retaining agent in this invention is as follows: Figure 1 As shown.

[0030] The reagents and pharmaceuticals used in the embodiments of this invention are all of industrial grade (inclusive) or higher purity, and their quantities are based on weight parts.

[0031] Comparative Example The difference between this comparative example and Example 1 is that the pH adjuster was replaced with an equal mass of NaOH, the spacing adjuster was replaced with an equal mass of N,N′-methylenebisacrylamide, the initiator was replaced with an equal mass of sodium persulfate, and the skeleton support agent, charge regulator, and thickener were not used. All other conditions were the same as in Example 1. This comparative example yielded a conventional acrylic-based water-retaining agent for agricultural and forestry use.

[0032] Experimental Example In this experimental example, Example 1 and the comparative example were used as experimental samples to conduct the following effect verification tests and analyses: 1. Infrared spectroscopy test Weigh 1.0 g of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry prepared in Example 1, mix it with potassium bromide, grind and compress it into tablets, and test the infrared spectrum results of Example 1 as follows. Figure 2 As shown; the test operating parameters are: wavenumber 500cm. -1 ~4000cm -1 .

[0033] 2. Freshwater swelling performance and reversible response performance Weigh 0.3g of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry prepared in Example 1, soak it in fresh water, and test the water absorption and swelling rate (SR) at different soaking time points. Figure 3 The diagram shows the swelling performance of the broad-spectrum stress-resistant agricultural and forestry water-retaining agent of Example 1 of the present invention in fresh water and its reversible response performance in NaCl brine. Wherein, as... Figure 3 A represents the swelling properties of a broad-spectrum stress-resistant water-retaining agent in fresh water, such as... Figure 3 B is a schematic diagram of the reversible response performance in NaCl brine.

[0034] like Figure 3 As shown in Figure A, the SR (surface resistivity) of the broad-spectrum stress-resistant water-retaining agent in fresh water is 2500 g / g; after a swelling time of 1500 minutes, the SR tends to stabilize. The relatively long time to reach saturation swelling is due to the swelling kinetic control effect caused by multiple charge interactions, passivation effects, and buffering effects. The reversible responsiveness in NaCl brine is shown in Figure A. Figure 3 B, the NaCl concentration is increased from 0.1% to 10%, and then gradually diluted to 0.1%, and the SR of the water-retaining agent changes periodically and reversibly.

[0035] 3. Swelling properties in brine and fertilizer solutions Weigh 0.3g of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry prepared in Example 1, and soak it in different types and concentrations of salt water until it swells and becomes saturated. Figure 4 The diagram shows the swelling properties of a broad-spectrum stress-resistant water-retaining agent in salt water or fertilizer solutions. Figure 4 The salt solution of A includes NaCl, CaCl2, MgCl2, NH4HCO3, KCl, and K2SO4; Figure 4 The salt solution in B contains KH2PO4, K2HPO4, and K3PO4; The water-retaining agent exhibits an SR > 70 g / g in NaCl brine with a mass concentration of 0.1%–20%, an SR > 40 g / g in CaCl2 or MgCl2 brine with a mass concentration of 0.1%–10%, an SR > 60 g / g in ammonium carbonate, KCl, or K2SO4 brine with a mass concentration of 0.1%–10%, and an SR > 70 g / g in KH2PO4, K2HPO4, or K3PO4 brine with a mass concentration of 0.1%–5%.

[0036] 4. Swelling properties under different pH conditions Weigh 0.3g of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry prepared in Example 1, and soak it in fresh water or mixed saline solution (10% NaCl + 2% KCl + 2% CaCl2 + 2% MgCl2) of different pH values ​​until it swells to saturation. Figure 5 As shown. In fresh water with a pH range of 2 to 11, the SR of the broad-spectrum stress-resistant agricultural and forestry water-retaining agent is >100 g / g, and in mixed saline solution (10% NaCl + 2% KCl + 2% CaCl2 + 2% MgCl2) with a pH range of 2 to 11, the SR is >50 g / g.

[0037] 5. Environmental scanning electron microscopy analysis (ESEM test results) The microstructure of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry prepared in Example 1 after swelling and saturation in a mixed saline solution of (10% NaCl + 2% KCl + 2% CaCl2 + 2% MgCl2) or a 10 wt% copper sulfate aqueous solution was observed using environmental scanning electron microscopy (ESEM). Under a test voltage of 30 kV (100 μm scale), as shown... Figure 6 The image shown is an environmental scanning electron microscope (ESEM) image of the broad-spectrum stress-resistant agricultural and forestry water-retaining agent prepared in Example 1 after swelling in a mixed saline solution of (10% NaCl + 2% KCl + 2% CaCl2 + 2% MgCl2); from Figure 6 It can be seen that the saturated broad-spectrum stress-resistant water-retaining agent for agriculture and forestry maintains a clear three-dimensional network structure in the mixed salt water, and has good swelling performance.

[0038] like Figure 7 The image shown is an environmental scanning electron microscope (ESEM) image of the broad-spectrum stress-resistant agricultural and forestry water-retaining agent of Example 1 after swelling in 10% CuSO4 saline solution; from Figure 7 It can be seen that at high concentrations of Cu 2+ In the environment, the broad-spectrum stress-resistant water-retaining agent for agriculture and forestry exhibits excellent adsorption performance while maintaining its three-dimensional molecular network and good compatibility.

[0039] 6. X-ray synchrotron radiation characterization analysis (XAFS test results) The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry prepared in Example 1 swells and adsorbs Cu. 2+ After saturation (initial copper sulfate concentrations of 1 wt% (sample Cu1) and 10 wt% (sample Cu2), XAFS analysis was performed and compared with elemental copper (sample Cu-foil). Energy calibration of the samples was performed using standard copper foil to determine the coordination number of the Cu-N / O / Cu scattering pathway in the samples. Figure 8 The image shows the adsorption of Cu by the broad-spectrum stress-resistant water-retaining agent in agricultural and forestry systems, as described in Example 1. 2+ X-ray synchrotron radiation characterization images (XAFS test results) after saturation (initial copper sulfate concentrations of 1 wt% and 10 wt%). Figure 8As shown, compared with elemental copper, the Cu1 sample exhibits a certain Cu-Cu signal in its outer shell, with bond lengths not significantly different from those of Cu-foil. However, the Cu-Cu signal in the Cu2 outer shell has a longer bond length, unlike Cu1. This suggests that the Cu2 sample may have adsorbed some Cu ions, forming a structure similar to CuOx. In other words, the Cu ions in the Cu2 sample may have been influenced by environmental Cu ions. 2+ With increasing concentration, the adsorption and fixation effect of the broad-spectrum stress-resistant agricultural and forestry water-retaining agent on copper is enhanced.

[0040] 7. Comparison of soilless germination and stress-resistant growth of mung beans The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops prepared in Example 1 and the conventional acrylic water-retaining agent for agricultural and forestry crops prepared in the comparative example were respectively embedded in white quartz sand, placed in plastic cups, and thoroughly watered with a fertilizer solution (0.05% potassium dihydrogen phosphate + 0.1% urea by mass concentration) for mung bean germination experiments. The quartz sand was sterilized at 100°C beforehand. Figure 9 The figure shown is a test diagram of the drought resistance performance of mung bean sprouts under soilless drought stress and the effect of chemical fertilizer.

[0041] The germination process simulated a soilless drought stress environment with added fertilizer. After the initial thorough watering, no further watering was done. The plant was then placed in a dark environment at 25°C for 7 days. The root development results after 7 days of stress-resistant growth are as follows: Figure 9 As shown in Figure A. The test results for adding the broad-spectrum stress-resistant water-retaining agent from Example 1 of this invention are shown in Figure A. Figure 9 A3, the test results of the blank sample without added agricultural and forestry water-retaining agents are shown in [reference needed]. Figure 9 A1. The test results of adding an equal amount of conventional acrylic water-retaining agent (comparative example) to the sample are shown in the figure. Figure 9 A2. Figure 9 Results A showed that, under soilless and fertilizer-free conditions and drought stress for 7 days, the addition of the broad-spectrum stress-resistant agricultural and forestry water-retaining agent described in Example 1 of this invention significantly improved the root development of mung beans. Figure 9 A3) is superior to adding an equal amount of the comparative sample. Figure 9 A2), and the root system of the blank sample without the addition of agroforestry water-retaining agents ( Figure 9 A1) has the worst development.

[0042] Subsequently, the plant underwent further phototropic growth at 25℃ for 15 days, and the growth results were observed. Figure 9 B. The test results for the addition of the broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops described in Example 1 of this invention are shown below. Figure 9 B3, the test results of the blank sample without added agricultural and forestry water-retaining agents are shown in [the original text]. Figure 9 B1. The test results of adding an equal amount of conventional acrylic water-retaining agent (comparative example) to the sample are shown in the figure. Figure 9 B2. Figure 9Results B showed that, under soilless and fertilizer-free conditions and drought stress for 15 days, the mung bean sprouts treated with the broad-spectrum stress-resistant agricultural and forestry water-retaining agent described in Example 1 of this invention exhibited better growth performance. Figure 9 B3) is superior to adding an equal amount of the comparative sample. Figure 9 B2), and the bud development of the blank sample without the addition of agroforestry water-retaining agents ( Figure 9 B1) is the worst relative to B1.

[0043] The reason for the difference in the results of the soilless germination and stress-resistant growth test of mung beans is that: quartz sand has poor water retention capacity, and the blank sample without added agricultural and forestry water-retaining agents suffered severe water loss and could not continuously provide water for plant growth. Therefore, the root system of the sample grown in the dark for 7 days was the shortest. Figure 9 A1), (7 days of growth in darkness + 8 days of growth in light) buds completely withered. Figure 9 B1); The sample with added conventional acrylic-based agricultural and forestry water-retaining agent (comparative example) showed that because the water-retaining agent absorbs water, swells, locks in moisture, and then slowly releases it, it can continuously provide water for plant growth under drought stress. Therefore, the root system of plants growing in the dark for 7 days ( Figure 9 A2) was superior to the blank sample, and a certain percentage of the buds that underwent (7 days of dark growth + 8 days of light-induced growth) survived. Figure 9 B2); The sample containing the broad-spectrum stress-resistant water-retaining agent of Example 1 of this invention exhibits advantages such as a stimulus-response passivation region formed by the three-dimensional network inert support of the skeleton support and thickener, a buffer region formed by the pH adjuster, charge effect self-adaptability, swelling kinetic control, and controllable spacing adjustment grid. This results in good compatibility with fertilizer solutions, high SR values ​​under various environmental stimuli, and longer water retention time. The comparative sample does not possess these properties, therefore the root system grown in the dark for 7 days (…) Figure 9 A3) showed the best bud growth compared to the control group (7 days of dark growth + 8 days of light-induced growth). Figure 9 B3).

[0044] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops, characterized in that: It includes the following components by weight: 100 parts acrylic acid, 5 to 20 parts pH adjuster, 50 to 200 parts skeleton support agent, 20 to 100 parts charge adjuster, 10 to 20 parts thickener, 0.2 to 0.5 parts spacing adjuster, 1 to 20 parts initiator, and 500 to 2000 parts water; The skeletal support is an electrically neutral compound containing hydroxyl active groups; The charge regulator is a cationic monomer or a zwitterionic monomer containing an acrylic acid derivative molecular structure. The spacing adjuster is a compound with multiple active functional groups or an oligomer.

2. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 1, characterized in that: The electrically neutral compound can be graft copolymerized, has a molecular weight of <200 g / mol, and is amphiphilic (hydrophilic and lipophilic), and is soluble in water, ethanol, or acetone.

3. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 2, characterized in that: The scaffold support is 4-hydroxybutyl acrylate.

4. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 1, characterized in that: The charge regulator is N-(2-acryloyloxyethyl)-N-benzyl-N,N-dimethylammonium chloride.

5. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 1, characterized in that: The spacing regulator has a molecular weight of 140 g / mol to 1200 g / mol, and the spacing regulator can be grafted copolymerized with hydroxyl groups or carbon-carbon double bonds.

6. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 5, characterized in that: The spacing adjuster is 1,4-hydroxybutylacrylate glycidyl ether.

7. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 1, characterized in that: The pH adjuster is an alkali metal phosphate or an alkaline earth metal phosphate.

8. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 7, characterized in that: The pH adjuster is sodium tripolyphosphate.

9. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 1, characterized in that: The thickener is a polymer formed by the dehydration condensation of α-D-glucose structural units.

10. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 9, characterized in that: The thickener is glycogen.

11. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 1, characterized in that: The initiator is a composite initiation system composed of vanadium oxalate and sodium persulfate.

12. The broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to claim 11, characterized in that: The mass ratio of vanadium oxalate to sodium persulfate is 1:5 to 1:

20.

13. A method for preparing a broad-spectrum stress-resistant water-retaining agent for agricultural and forestry crops according to any one of claims 1-12, characterized in that: Includes the following steps: S1. Mix acrylic acid, pH adjuster, skeleton support agent, charge adjuster, thickener, spacing adjuster and water at 60℃~80℃, stir in a closed container for 20~50 minutes, and then cool to room temperature to obtain a mixed system; S2. Add the initiator to the mixing system, stir to dissolve, pour into a mold, seal with nitrogen, keep at 70℃ for 1 to 3 hours, remove, let stand at room temperature for 6 to 12 hours, demold, dry and pulverize at 50 to 80℃, and pass through a 100 to 200 mesh sieve to obtain the broad-spectrum stress-resistant agricultural and forestry water-retaining agent.

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