阅读说明：本技术 一种复合缓释肥吸水纤维及其制备方法和应用 (Composite slow-release fertilizer water-absorbing fiber and preparation method and application thereof ) 是由 杨琳 王中珍 丁帅 于 2019-10-18 设计创作，主要内容包括：本发明提供了一种复合缓释肥吸水纤维及其制备方法和应用,属于吸水纤维技术领域。本发明提供了一种复合缓释肥吸水纤维的制备方法,包括以下步骤：在保护性气氛条件下,将丙烯酸、丙烯酸盐、丙烯酰胺、聚乙烯醇、交联剂和水混合,得到反应液；在保护性气氛条件下,将所述反应液和引发剂混合,进行溶液聚合反应,得到聚合物溶液；在保护性气氛条件下,将所述聚合物溶液和磷酸镁铵混合,进行共混复合反应,得到聚合物纺丝溶液；将所述聚合物纺丝溶液依次进行溶液纺丝和交联反应,得到复合缓释肥吸水纤维。本发明制备的复合缓释肥吸水纤维的缓释肥料时间长,而且吸水和保水功能优异。(The invention provides a composite slow-release fertilizer water-absorbing fiber and a preparation method and application thereof, belonging to the technical field of water-absorbing fibers. The invention provides a preparation method of composite slow release fertilizer water absorption fiber, which comprises the following steps: mixing acrylic acid, acrylate, acrylamide, polyvinyl alcohol, a cross-linking agent and water under the condition of protective atmosphere to obtain a reaction solution; under the condition of protective atmosphere, mixing the reaction solution and an initiator to carry out solution polymerization reaction to obtain a polymer solution; under the condition of protective atmosphere, mixing the polymer solution and ammonium magnesium phosphate, and carrying out blending composite reaction to obtain a polymer spinning solution; and sequentially carrying out solution spinning and crosslinking reaction on the polymer spinning solution to obtain the composite slow-release fertilizer water-absorbing fiber. The composite slow release fertilizer water absorption fiber prepared by the invention has long time of slow release fertilizer and excellent water absorption and retention functions.)

1. The preparation method of the composite slow release fertilizer water absorption fiber is characterized by comprising the following steps:

mixing acrylic acid, acrylate, acrylamide, polyvinyl alcohol, a cross-linking agent and water under the condition of protective atmosphere to obtain a reaction solution;

under the condition of protective atmosphere, mixing the reaction solution and an initiator to carry out solution polymerization reaction to obtain a polymer solution;

under the condition of protective atmosphere, mixing the polymer solution and ammonium magnesium phosphate, and carrying out blending composite reaction to obtain a polymer spinning solution;

and sequentially carrying out solution spinning and crosslinking reaction on the polymer spinning solution to obtain the composite slow-release fertilizer water-absorbing fiber.

2. The preparation method of claim 1, wherein the acrylate accounts for 60-85% of the total molar amount of the acrylic acid and the acrylate;

the mass ratio of the acrylamide to the acrylic acid is (0.15-0.45): 1;

the mass ratio of the total mass of the acrylamide and the acrylic acid to the mass of the polyvinyl alcohol and the cross-linking agent is 100: (25-45): (0.02-0.1);

the total concentration of acrylic acid, acrylamide and polyvinyl alcohol in the reaction liquid is 15-20 wt%.

3. The production method according to claim 1 or 2, characterized in that the initiator comprises ammonium persulfate and/or potassium persulfate;

the cross-linking agent comprises N, N-methylene bisacrylamide, glutaraldehyde, N-hydroxymethyl acrylamide, hydroxyethyl acrylate or hydroxypropyl acrylate.

4. The method according to claim 1 or 2, wherein the mass ratio of the total mass of the acrylamide and acrylic acid to the initiator is 100: (0.2 to 1).

5. The production method according to claim 1 or 2, characterized in that the mass ratio of the total mass of the acrylamide and acrylic acid to the magnesium ammonium sulfate is 100: (5-20).

6. The method according to claim 1, wherein the solution polymerization is carried out at a temperature of 55 to 70 ℃ for 2 to 3 hours.

7. The preparation method of claim 1, wherein the temperature of the blending composite reaction is 40-50 ℃ and the time is 1-4 h.

8. The method for preparing the fiber according to claim 1, wherein the working parameters of the solution spinning are as follows: the drawing multiple is 1-2 times, and the coagulating bath is an ethanol solution;

the temperature of the crosslinking reaction is 105-115 ℃, and the time is 10-20 min.

9. The composite slow release fertilizer water absorption fiber prepared by the preparation method of any one of claims 1 to 8.

10. The use of the composite slow release fertilizer water absorption fiber of claim 9 in agriculture, forestry, horticulture, slope protection, bank protection, desert control, water and soil conservation, soilless culture, non-woven products or plant growing materials.

Technical Field

The invention relates to the technical field of water-absorbing fibers, in particular to a composite slow-release fertilizer water-absorbing fiber and a preparation method and application thereof.

Background

The conventional slow release fertilizer mainly comprises a synthetic organic nitrogen fertilizer, a coated fertilizer, a slow-soluble inorganic fertilizer and an ammoniated fertilizer taking natural organic matters as a matrix, and does not have the functions of water absorption and water retention. In addition, some slow release fertilizers with water absorption and retention properties are available, the preparation methods include a coating method (the water absorbent is a film layer and the fertilizer is a core) and a blending method (finished water absorbent particles are blended with the slow release fertilizer), and the coating method and the blending method have the defects of uneven fertilizer distribution, influence on the slow release effect and are not suitable for a non-woven production process.

Disclosure of Invention

In view of the above, the invention aims to provide a composite slow release fertilizer water absorption fiber, and a preparation method and application thereof. The water-absorbing fiber of the compound slow-release fertilizer provided by the invention has good water-absorbing, water-retaining and slow-release functions.

In order to achieve the above object, the present invention provides the following technical solutions: a preparation method of composite slow release fertilizer water absorption fiber comprises the following steps:

mixing acrylic acid, acrylate, acrylamide, polyvinyl alcohol, a cross-linking agent and water under the condition of protective atmosphere to obtain a reaction solution;

under the condition of protective atmosphere, mixing the reaction solution and an initiator to carry out solution polymerization reaction to obtain a polymer solution;

under the condition of protective atmosphere, mixing the polymer solution and ammonium magnesium phosphate, and carrying out blending composite reaction to obtain a polymer spinning solution;

and sequentially carrying out solution spinning and crosslinking reaction on the polymer spinning solution to obtain the composite slow-release fertilizer water-absorbing fiber.

Preferably, the acrylate accounts for 60-85% of the total molar weight of the acrylic acid and the acrylate;

the mass ratio of the acrylamide to the acrylic acid is (0.15-0.45): 1;

the mass ratio of the total mass of the acrylamide and the acrylic acid to the mass of the polyvinyl alcohol and the cross-linking agent is 100: (25-45): (0.02-0.1);

the concentration of acrylic acid, acrylamide and polyvinyl alcohol in the reaction liquid is 15-20 wt%.

Preferably, the initiator comprises ammonium persulfate and/or potassium persulfate;

the cross-linking agent comprises N, N-methylene bisacrylamide, glutaraldehyde, N-hydroxymethyl acrylamide, hydroxyethyl acrylate or hydroxypropyl acrylate.

Preferably, the mass ratio of the total mass of the acrylamide and the acrylic acid to the initiator is 100: (0.2 to 1).

Preferably, the mass ratio of the total mass of the acrylamide and the acrylic acid to the magnesium ammonium sulfate is 100: (5-20).

Preferably, the temperature of the solution polymerization reaction is 55-70 ℃ and the time is 2-3 h.

Preferably, the temperature of the blending composite reaction is 40-50 ℃, and the time is 1-4 h.

Preferably, the working parameters of the solution spinning are as follows: the drawing multiple is 1-2 times, and the coagulating bath is an ethanol solution;

the temperature of the crosslinking reaction is 105-115 ℃, and the time is 10-20 min.

The invention provides the composite slow release fertilizer water absorption fiber prepared by the preparation method of the technical scheme.

The invention also provides the application of the composite slow release fertilizer water absorption fiber in agriculture, forestry and gardening, slope protection and bank protection, desert control, water and soil conservation, soilless culture, non-woven products or plant growing materials.

The invention provides a preparation method of composite slow release fertilizer water absorption fiber, which comprises the following steps: mixing acrylic acid, acrylate, acrylamide, polyvinyl alcohol, a cross-linking agent and water under the condition of protective atmosphere to obtain a reaction solution; under the condition of protective atmosphere, mixing the reaction solution and an initiator to carry out solution polymerization reaction to obtain a polymer solution; under the condition of protective atmosphere, mixing the polymer solution and ammonium magnesium phosphate, and carrying out blending composite reaction to obtain a polymer spinning solution; and sequentially carrying out solution spinning and crosslinking reaction on the polymer spinning solution to obtain the composite slow-release fertilizer water-absorbing fiber. According to the invention, the composite slow release fertilizer water absorption fiber with a complex and compact network structure is obtained through a special preparation process, on one hand, when the composite slow release fertilizer water absorption fiber is contacted with water, the composite slow release fertilizer water absorption fiber gradually swells into hydrogel and finally reaches swelling balance, in the process, magnesium ammonium phosphate particles distributed in a high water absorption polymer network structure are gradually dissolved to form a free aqueous solution capable of dynamically exchanging with a soil solution, and nutrients in the composite slow release fertilizer water absorption fiber are continuously and slowly released into the soil along with the dynamic exchange of the solution; on the other hand, in the long-term contact process of the composite slow-release fertilizer water-absorbing fiber and water, the macromolecular chains of the composite slow-release fertilizer water-absorbing fiber are broken, magnesium ions and ammonium ions which are bonded to the macromolecular chains directly enter the soil solution and are also released into the soil along with the dynamic exchange of the solution, the process is slow and long in duration, and the nutrient slow release of the composite slow-release fertilizer water-absorbing fiber is realized. The water-absorbing fiber of the compound slow-release fertilizer provided by the invention has good functions of water absorption, water retention and slow release.

Drawings

FIG. 1 is a schematic view of a solution spinning process, wherein, a-a storage tank; b-a spinneret; c-a coagulation bath; d-a drawing roll; e-hot drawing box; f-a winding roll;

FIG. 2 is a reaction scheme of a polymer in a polymer solution;

FIG. 3 is a schematic structural diagram of water-absorbing fibers of the compound slow-release fertilizer;

FIG. 4 is a schematic diagram of a nutrient slow release mechanism of the water absorbent fiber of the compound slow release fertilizer;

FIG. 5 is an SEM photograph of water absorbent fibers of the compound slow release fertilizer prepared in example 1;

FIG. 6 is an SEM photograph of a cross section of water absorbent fibers of the compound slow release fertilizer prepared in example 1, wherein a is a cross section view and b is a partially enlarged cross section view;

FIG. 7 is a FTIR chart of water absorbent fibers of the composite slow release fertilizer prepared in example 1;

FIG. 8 is an SEM photograph of a cross section of water absorbent fibers of the compound slow release fertilizer prepared in example 2, wherein a is a cross sectional view and b is a partially enlarged cross sectional view;

fig. 9 is an SEM picture of a cross section of the composite slow release fertilizer water absorbent fiber prepared in example 3, wherein a is a cross sectional view and b is a partially enlarged cross sectional view.

Detailed Description

The invention provides a preparation method of composite slow release fertilizer water absorption fiber, which comprises the following steps:

mixing acrylic acid, acrylate, acrylamide, polyvinyl alcohol, a cross-linking agent and water under the condition of protective atmosphere to obtain a reaction solution;

under the condition of protective atmosphere, mixing the reaction solution and an initiator to carry out solution polymerization reaction to obtain a polymer solution;

under the condition of protective atmosphere, mixing the polymer solution and ammonium magnesium phosphate, and carrying out blending composite reaction to obtain a polymer spinning solution;

and sequentially carrying out solution spinning and crosslinking reaction on the polymer spinning solution to obtain the composite slow-release fertilizer water-absorbing fiber.

In the present invention, all the raw material components are commercially available products well known to those skilled in the art unless otherwise specified.

The method comprises the steps of mixing acrylic acid, acrylate, acrylamide, polyvinyl alcohol, a cross-linking agent and water under the condition of protective atmosphere to obtain a reaction solution.

The protective atmosphere in the present invention is not particularly limited, and protective atmospheres known in the art, such as nitrogen and argon, may be used.

In the invention, the acrylic acid and the alkaline reagent are preferably subjected to neutralization reaction to obtain a mixed solution of acrylic acid and acrylate. In the present invention, the alkaline agent is preferably NaOH, KOH, or ammonia water. In the invention, the acrylate preferably accounts for 60-85% of the total molar amount of the acrylic acid and the acrylate, that is, the neutralization degree of the acrylic acid is preferably 60-85%, more preferably 65-80%, and most preferably 70-75%.

In the present invention, the crosslinking agent preferably includes N, N-methylenebisacrylamide, glutaraldehyde, N-methylolacrylamide, hydroxyethyl acrylate, or hydroxypropyl acrylate, and more preferably N, N-methylenebisacrylamide. In the present invention, the crosslinking agent is preferably used in the form of an aqueous crosslinking agent solution; the concentration of the cross-linking agent aqueous solution is preferably 0.1 to 1.0 wt%, more preferably 0.1 to 0.5 wt%, and most preferably 0.1 wt%. In the present invention, the mass ratio of acrylamide to acrylic acid is preferably (0.15 to 0.45): 1, more preferably (0.25 to 0.45): 1, most preferably (0.2 to 0.3): 1.

in the present invention, the polyvinyl alcohol is preferably polyvinyl alcohol 1799; the polyvinyl alcohol is preferably used in the form of an aqueous polyvinyl alcohol solution; the concentration of the polyvinyl alcohol aqueous solution is preferably 10-15 wt%, more preferably 10-13 wt%, and most preferably 10-11 wt%. In the present invention, the mass ratio of the total mass of the acrylamide and the acrylic acid to the polyvinyl alcohol and the crosslinking agent is preferably 100: (25-45): (0.02 to 0.1), more preferably 100: (25-40): (0.04 to 0.08), most preferably 100: (25-30): (0.05-0.06).

In the present invention, the concentration of acrylic acid, acrylamide and polyvinyl alcohol in the reaction solution is preferably 15 to 20 wt%, more preferably 16 to 19 wt%, and most preferably 17 to 18 wt%. In the present invention, the water in the reaction solution preferably includes water in the above-described component solutions (the alkali agent, the crosslinking agent aqueous solution, and the polyvinyl alcohol aqueous solution), and it is sufficient to ensure that the contents of the components are within the above-described ranges.

In the invention, the mixing temperature is preferably 20-40 ℃, and more preferably 25-30 ℃; the mixing time is preferably 10-30 min, and more preferably 10-20 min; the mixing time is preferably based on complete dissolution of the acrylamide.

After the reaction solution is obtained, the reaction solution and the initiator are mixed under the protective atmosphere condition to carry out solution polymerization reaction, so as to obtain the polymer solution.

The protective atmosphere used in the present invention is not particularly limited, and any protective atmosphere known in the art may be used, specifically, nitrogen or argon.

In the present invention, the mass ratio of the total mass of the acrylamide and the acrylic acid to the initiator is 100: (0.2 to 1), more preferably 100: (0.4 to 0.8), most preferably 100: (0.4-0.6). In the present invention, the initiator preferably comprises ammonium persulfate and/or potassium persulfate, more preferably ammonium persulfate or potassium persulfate. In the present invention, the initiator is preferably used in the form of an aqueous initiator solution, and the concentration of the aqueous initiator solution is preferably 4 to 8 wt%, more preferably 4 to 7 wt%, and most preferably 4 to 6 wt%.

In the present invention, the reaction solution and the initiator are preferably mixed in such a manner that the initiator is added dropwise to the reaction solution; the dropping speed of the initiator is not particularly limited in the present invention, and may be a dropping speed well known in the art. In the invention, the mixing temperature is preferably 55-65 ℃, more preferably 57-62 ℃, and most preferably 60 ℃.

In the invention, the temperature of the solution polymerization reaction is preferably 55-70 ℃, and the time is preferably 2-3 h. In the invention, the solution polymerization reaction is preferably carried out for 1-1.5 h at 55-60 ℃, and then for 1-1.5 h after the temperature is raised to 65-70 ℃. The solution polymerization reaction is carried out at different temperatures, so that the solution polymerization reaction process is convenient to control, and raw materials are prevented from being gathered suddenly, and the water absorption, water retention and slow-release fertilizer performance of the composite slow-release fertilizer water absorption fiber are further influenced.

In the invention, the reaction generated in the solution polymerization reaction process is that acrylic acid, acrylate and acrylamide generate acrylate (acrylic acid) acrylamide copolymer under the action of an initiator; under the action of heating and an initiator, the acrylate (acrylic acid) acrylamide copolymer, the polyvinyl alcohol and the cross-linking agent can be subjected to cross-linking between the acrylate (acrylic acid) acrylamide copolymer and the situation that a long chain of the polyvinyl alcohol is inserted into the acrylate (acrylic acid) acrylamide copolymer network, and finally a semi-interpenetrating network structure is formed, and the polymer in the prepared polymer solution is an acrylate (acrylic acid) -acrylamide/polyvinyl alcohol polymer, which is abbreviated as P (AANa (AA) -co-AM)/PVA polymer.

After the solution polymerization reaction is completed, the method preferably further comprises the step of reducing the temperature of the obtained reaction system to 40-50 ℃, and more preferably to 45 ℃.

After the polymer solution is obtained, the polymer solution and the magnesium ammonium phosphate are mixed under the protective atmosphere condition, and blending composite reaction is carried out to obtain the polymer spinning solution.

The protective atmosphere in the present invention is not particularly limited, and protective atmospheres known in the art, such as nitrogen and argon, may be used.

In the invention, the particle size of the Magnesium Ammonium Phosphate (MAP) is preferably less than 300 meshes, and more preferably 300-800 meshes. In the present invention, the mass ratio of the total mass of the acrylamide and acrylic acid to the magnesium ammonium sulfate is preferably 100: (5-20), more preferably 100: (10-20), most preferably 100: (10-15). The invention controls the addition of the magnesium ammonium phosphate, and is beneficial to controlling the slow release period of the magnesium ammonium phosphate.

In the present invention, the polymer solution and the magnesium ammonium phosphate are preferably mixed in such a manner that the magnesium ammonium phosphate is added to the polymer solution in portions, and the amount of the magnesium ammonium phosphate added each time is preferably 10% of the total mass of the magnesium ammonium phosphate. According to the invention, the magnesium ammonium phosphate is added into the polymer solution in several times, so that the magnesium ammonium phosphate can be dispersed more uniformly.

In the invention, the temperature of the blending composite reaction is preferably 40-50 ℃, and more preferably 45-50 ℃; the time of the blending composite reaction is preferably 1-4 h, and more preferably 2-3 h. In the invention, when the temperature of the polymer solution is lower, the viscosity is higher, the stirring is difficult, and MAP can not be fully dispersed in the polymer solution; when the temperature of the polymer solution is higher, part of the unreacted monomers in the polymer solution continue to react, so that the viscosity is increased, and the dispersion of MAP in the polymer solution is also influenced. The temperature of the blending composite reaction is controlled to be 40-50 ℃, and the polymer solution is stable, so that the addition and the reaction of MAP are facilitated. In the present invention, the polymer in the polymer spinning solution prepared is an acrylate (acrylic acid) -acrylamide/polyvinyl alcohol/magnesium ammonium phosphate polymer, abbreviated as P (aana (aa) -co-AM)/PVA/MAP polymer.

After the blending composite reaction is completed, the present invention preferably further comprises reducing the temperature of the resulting reaction system to room temperature.

After the polymer spinning solution is obtained, the polymer spinning solution is sequentially subjected to solution spinning and crosslinking reaction to obtain the composite slow-release fertilizer water-absorbing fiber.

In the present invention, it is preferable that the method further comprises defoaming the polymer spinning solution before the solution spinning. In the present invention, the deaeration is preferably performed in a storage tank of the spinning solution of the wet spinning hand sample machine. In the invention, the defoaming mode is preferably static defoaming, and the time for static defoaming is preferably 24-48 h, and more preferably 24-36 h.

In the invention, the working parameters of the solution spinning are as follows: the drafting multiple is preferably 1-2 times, and more preferably 2 times; the coagulating bath is preferably an ethanol solution, and the volume fraction of ethanol in the ethanol solution is preferably 50-75%, and more preferably 50-60%. In the invention, the temperature of the coagulating bath is preferably 25-30 ℃, and more preferably 30 ℃.

In the invention, the process schematic diagram of the solution spinning is shown in fig. 1, wherein in fig. 1, a is a storage tank; b is a spinning nozzle; c is a coagulating bath; d is a drafting roller; e is a hot drawing box; f is a winding roll.

In the present invention, the process of the solution spinning is preferably: and (3) standing and defoaming the spinning solution, heating to 45-50 ℃, spraying the spinning solution from a spinning nozzle through a metering pump and a filter, feeding the spinning solution into an ethanol solution coagulation bath, wherein the temperature of the coagulation bath is 25-30 ℃, the coagulation time is 2-5 min, feeding the obtained nascent fiber into a hot drawing box with the temperature of 40-50 ℃, and winding the nascent fiber onto a winding roller after hot drawing for 5 min.

In the invention, the temperature of the crosslinking reaction is preferably 105-115 ℃, more preferably 105 ℃, and the time of the crosslinking reaction is preferably 10-20 min, more preferably 15-20 min.

In the invention, the composite slow release fertilizer water absorption fiberThe reactions that occur during the preparation of the vitamin are as follows: acrylic acid, acrylate and acrylamide generate an acrylate (acrylic acid) acrylamide copolymer under the initiation of an initiator, and under the initiation of an initiator, the acrylate sodium (acrylic acid) acrylamide copolymer, polyvinyl alcohol and a cross-linking agent can be subjected to cross-linking between the acrylate (acrylic acid) acrylamide copolymers and the situation that long polyvinyl alcohol chains are inserted into an acrylate (acrylic acid) acrylamide copolymer network, so that a semi-interpenetrating network structure is finally formed, and the reaction flow chart of the prepared polymer is shown in fig. 2. Since the magnesium ammonium phosphate in the polymer spinning solution is randomly distributed, part of the magnesium ammonium phosphate can also react with the unneutralized acrylic acid present in the polymer spinning solution as shown in formula (1) and/or formula (2), and Mg²⁺And NH⁴⁺In the presence of a base which forms-COO-Mg-OOC-and-COONH₄The structure of the composite slow release fertilizer water absorption fiber is more complex and compact, and the structure of the composite slow release fertilizer water absorption fiber is shown in figure 3.

NH₄MgPO₄+H⁺＝Mg²⁺+NH⁴⁺+HPO₄ ^2-Formula (1)

NH₄MgPO₄+2H⁺＝2Mg²⁺+NH⁴⁺+H₂PO₄ ^2-Formula (2).

In the invention, the schematic diagram of the slow release mechanism of the water absorption fiber of the compound slow release fertilizer is shown in fig. 4: the nutrient in the water-absorbing fiber of the composite slow-release fertilizer has slow release performance which is determined by the existence form of magnesium ammonium phosphate in the fiber, and partial magnesium ammonium phosphate reacts with acrylic acid to lead Mg to react²⁺、NH⁴⁺The polymer chains are bonded, and the other part of the polymer chains are distributed in the network structure of the P (AANa (AA) -co-AM)/PVA polymer in the form of magnesium ammonium phosphate particles. On one hand, when the water absorption fiber of the compound slow release fertilizer contacts with water, the water absorption fiber gradually swells into hydrogel and finally reaches swelling balance, in the process, magnesium ammonium phosphate particles distributed in a P (AANa (AA) -co-AM)/PVA polymer network structure are gradually dissolved to form a part of free aqueous solution capable of dynamically exchanging with soil solution, and nutrients in the fiber are continuously and slowly released along with the dynamic exchange of the solutionPlacing into soil. On the other hand, during the long-term contact of the polymer network and water, the macromolecular chain of the P (AANa (AA) -co-AM)/PVA polymer is broken and bonded to the Mg on the macromolecular chain of the P (AANa (AA) -co-AM)/PVA polymer²⁺、NH⁴⁺The plasma can directly enter the soil solution and can be released into the soil along with the dynamic exchange of the solution, and the process is slow and long in duration. Therefore, the nutrient slow release of the water absorption fiber of the compound slow release fertilizer is realized.

The invention also provides the composite slow release fertilizer water absorption fiber prepared by the preparation method of the technical scheme.

In the invention, the composite slow-release fertilizer water-absorbing fiber comprises acrylate (acrylic acid) -acrylamide/polyvinyl alcohol polymer and ammonium magnesium phosphate. In the water absorption fiber of the compound slow release fertilizer, part of magnesium ammonium phosphate is distributed in a network structure of a P (AANa (AA) -co-AM)/PVA polymer in a particle form, and magnesium ions and ammonium ions in the other part of magnesium ammonium phosphate are bonded to a macromolecular chain of the P (AANa (AA) -co-AM)/PVA polymer.

In the invention, the length of the water absorption fiber of the compound slow release fertilizer is preferably 40 mm-60 mm, and more preferably 45 mm-55 mm.

In the composite slow-release fertilizer water absorption fiber provided by the invention, part of magnesium ammonium phosphate is distributed in a network structure of a P (AANa (AA) -co-AM)/PVA polymer in a particle form, and magnesium ions and ammonium ions in the other part of magnesium ammonium phosphate are bonded to a macromolecular chain of the P (AANa (AA) -co-AM)/PVA polymer to form-COO-Mg-OOC-and-COONH₄The structure makes the network structure of the P (AANa (AA) -co-AM)/PVA polymer more complex and compact. On one hand, when the composite slow release fertilizer water absorption fiber is contacted with water, the composite slow release fertilizer water absorption fiber gradually swells into hydrogel and finally reaches swelling balance, in the process, the magnesium ammonium phosphate particles distributed in the high water absorption polymer network structure are gradually dissolved to form a free aqueous solution capable of dynamically exchanging with a soil solution, and the nutrients in the composite slow release fertilizer water absorption fiber are continuously and slowly released into the soil along with the dynamic exchange of the solution. On the other hand, in the long-term contact process of the water-absorbing fiber of the composite slow-release fertilizer and water, macromolecular chains of the water-absorbing fiber are broken and bonded to waterMagnesium ions and ammonium ions on the polymer chains can directly enter the soil solution and can be released into the soil along with the dynamic exchange of the solution, the process is slow and long in duration, and the nutrient slow release of the composite slow-release fertilizer water-absorbing fibers is realized.

The invention provides the application of the composite slow release fertilizer water absorption fiber in the technical scheme or the composite slow release fertilizer water absorption fiber prepared by the preparation method in the technical scheme in agriculture, forestry and gardening, slope protection and bank protection, desert control, water and soil conservation, soilless culture, non-woven products or plant growing materials. In the invention, when the composite slow-release fertilizer water-absorbing fiber is used for non-woven products and functional plant-growing materials, the composite slow-release fertilizer water-absorbing fiber can be prepared into non-woven products with different specifications such as thickness, gram weight, porosity and the like by using a non-woven technology alone; or mixing with other fibers (such as noil, coconut fiber, etc.) to obtain nonwoven products with different properties; the prepared non-woven product can be combined with materials with certain functions (such as water and soil protection blankets, reinforced vegetation mats, ecological vegetation blankets and the like) to prepare the vegetation materials with multiple functions.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.