Slow-release agent for potassium chloride particles as well as preparation method and application of slow-release agent

Abstract

The invention discloses a slow-release agent for potassium chloride granules as well as a preparation method and application thereof, and particularly belongs to the technical field of fertilizer manufacturing. The slow-release agent is prepared from the following raw materials in parts by mass: 20 to 30 parts of starch, 10 to 13 parts of peanut shell phenol liquefied product, 4.5 to 6 parts of glycerol, 4 to 8 parts of polyvinyl alcohol and 11 to 13.5 parts of cross-linking agent. The slow-release agent provided by the invention can effectively prolong the release time of potassium chloride and reduce the short-time release rate of potassium chloride, the slow-release period can reach 110 days, and the utilization rate of potassium fertilizer by crops is improved; the slow-release agent and the slow-release potash fertilizer provided by the invention are simple in preparation process and can realize large-scale application.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizer manufacturing, and particularly relates to a slow-release agent for potassium chloride particles and a preparation method and application thereof. Background Art

[0002] In agricultural production, fertilizer is a key factor in improving soil fertility and promoting crop growth. Its type and performance have a direct impact on agricultural production benefits. With the continuous advancement of modern agricultural technology and the enhancement of environmental awareness, the fertilizer industry is developing towards high efficiency, specialization, functionality and greenness.

[0003] Potassium chloride is one of the important nutrients required for plant growth and is widely used in various fertilizers. However, there are some problems with traditional potassium chloride granular fertilizers during use, such as too fast nutrient release, low utilization rate, and multiple fertilization times. These problems limit its application effect and may have a negative impact on the environment.

[0004] In order to improve the utilization rate of potassium chloride granular fertilizer and reduce nutrient loss, researchers began to explore the slow-release technology of potassium chloride granules. Slow-release fertilizer controls the release rate of nutrients to better match the nutrient needs of crops, thereby improving fertilizer utilization and reducing the number of fertilization times. This technology can not only reduce the labor intensity of farmers, but also help reduce pollution to the environment.

[0005] However, the existing preparation process of potassium chloride granular slow-release fertilizer is often complicated, involving a variety of auxiliary materials and complex process steps, which not only increases the production cost but also may affect the stability and bioavailability of the fertilizer.

[0006] Therefore, it is of great significance to develop a potassium chloride granular slow-release fertilizer with simple preparation process, low cost, stable nutrient release and high utilization rate. Summary of the invention

[0007] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a new type of slow-release agent for potassium chloride granules, which can achieve the slow release of potassium chloride granules through specific raw materials and preparation methods, improve the utilization rate of fertilizers, reduce nutrient loss, and reduce production costs and pollution to the environment.

[0008] To achieve the above object, the present invention discloses the following technical solutions:

[0009] In a first aspect, the present invention provides a sustained-release agent for potassium chloride granules, wherein the sustained-release agent comprises the following raw materials in parts by mass:

[0010] 20-30 parts of starch;

[0011] 10-13 parts of peanut shell phenol liquefied material;

[0012] Glycerin 4.5-6 parts;

[0013] 4-8 parts of polyvinyl alcohol;

[0014] Crosslinking agent 11-13.5 parts.

[0015] Preferably, the starch is selected from at least one of cassava starch, sweet potato starch and potato starch.

[0016] Further preferably, the starch is selected from tapioca starch.

[0017] Preferably, the cross-linking agent is selected from at least one of glyoxal and genipin.

[0018] Further preferably, the cross-linking agent is composed of glyoxal and genipin in a mass ratio of (6-6.5):(5-7).

[0019] In a second aspect, the present invention provides use of the slow-release agent for potassium chloride granules described in the first aspect in the preparation of potassium chloride slow-release fertilizer.

[0020] In a third aspect, the present invention provides a method for preparing the sustained-release agent for potassium chloride granules according to the first aspect, the preparation method comprising the following steps:

[0021] Step 1-1. Accurately weigh cassava starch, mix cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir at 80-90°C and 50-100 r / min for 20 min to obtain gelatinized starch;

[0022] Step 1-2. Mix the formulated amount of peanut shell phenol liquefied product, glycerol, polyvinyl alcohol, glyoxal and genipin, add them to the gelatinized starch, stir and react at 65-70° C. and 100-200 r / min for 90-120 minutes to obtain a sustained-release agent.

[0023] In a fourth aspect, the present invention provides a method for preparing a potassium chloride slow-release fertilizer, the preparation method comprising the following steps:

[0024] Step 2-1. Place potassium chloride particles in a rotating drum, preheat to 70-75°C, add microcrystalline wax and precipitated silica, and mix at a speed of 10-20 r / min to obtain a mixture, wherein the mass ratio of the potassium chloride particles, microcrystalline wax and precipitated silica is 500:(3-4):(3-5);

[0025] Step 2-2. At a rotation speed of 10-20 r / min, use a spray gun to evenly spray the slow-release agent described in any one of claims 1-5 onto the surface of the mixture obtained in step 2-1, so that the surface of all potassium chloride particles is coated with the slow-release agent, and then vacuum dry the coated particles at 65-70°C and -0.08 mPa, cool to room temperature after drying, and sieve to obtain the potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 5-7wt%.

[0026] Beneficial effects of the present invention:

[0027] 1. The sustained-release agent provided by the present invention can effectively prolong the release time of potassium chloride and reduce the short-time release rate of potassium chloride. The sustained-release period can reach 110 days, thereby improving the utilization rate of potassium fertilizer by crops;

[0028] 2. The slow-release agent and slow-release potassium fertilizer provided by the present invention have simple preparation processes and can be applied on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to further understand the present invention, the present invention is described in detail below with reference to the accompanying drawings:

[0030] Figure 1 This is the cumulative release rate diagram of K. DETAILED DESCRIPTION

[0031] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] Unless otherwise specified, the test methods used in the specific implementation methods are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels; the percentages mentioned in the specific implementation methods, unless otherwise specified, are all mass percentages.

[0033] In the present invention:

[0034] Peanut shell phenol liquefact was purchased from Linyi Sanhe Biomass Technology Co., Ltd., with a solid content of 20-30% and a viscosity of 1000 mPa·s;

[0035] The remaining raw materials are commercially available.

[0036] Preparation of Example 1:

[0037] 1. Preparation of potassium chloride granules with sustained-release agent

[0038] Step 1-1. Accurately weigh 20 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 80°C and 50 r / min for 20 min to obtain gelatinized starch;

[0039] Step 1-2. 12.5 parts by mass of peanut shell phenol liquefied product, 4.5 parts by mass of glycerol, 4 parts by mass of polyvinyl alcohol, 6 parts by mass of glyoxal, and 5 parts by mass of genipin are mixed and added to the gelatinized starch, and stirred at 65° C. and 100 r / min for 90 minutes to obtain a sustained-release agent.

[0040] 2. Preparation of potassium chloride slow-release fertilizer

[0041] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 70°C, add 3 parts by mass of microcrystalline wax and 3 parts by mass of precipitated silica, and mix them at a speed of 10 r / min to obtain a mixture;

[0042] Step 2-2. At a rotation speed of 10 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 65°C and -0.08 mPa, cool to room temperature after drying, and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 5wt%.

[0043] Preparation of Example 2:

[0044] 1. Preparation of potassium chloride granules with sustained-release agent

[0045] Step 1-1. Accurately weigh 25 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 85°C and 100 r / min for 20 min to obtain gelatinized starch;

[0046] Step 1-2. 10 parts by mass of peanut shell phenol liquefied product, 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol, 6.7 parts by mass of glyoxal and 6 parts by mass of genipin are mixed and added to the gelatinized starch, and stirred at 67° C. and 150 r / min for 100 min to obtain a sustained-release agent.

[0047] 2. Preparation of potassium chloride slow-release fertilizer

[0048] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix them at a speed of 15 r / min to obtain a mixture;

[0049] Step 2-2. At a rotation speed of 15 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 67°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6wt%.

[0050] Preparation of Example 3:

[0051] 1. Preparation of potassium chloride granules with sustained-release agent

[0052] Step 1-1. Accurately weigh 30 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 90°C and 100 r / min for 20 min to obtain gelatinized starch;

[0053] Step 1-2. Mix 13 parts by mass of peanut shell phenol liquefied product, 6 parts by mass of glycerol, 8 parts by mass of polyvinyl alcohol, 6.5 parts by mass of glyoxal, and 7 parts by mass of genipin, add the mixture to the gelatinized starch, and stir the mixture at 70°C and 200 r / min for 120 min to obtain a sustained-release agent.

[0054] 2. Preparation of potassium chloride slow-release fertilizer

[0055] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 75°C, add 4 parts by mass of microcrystalline wax and 5 parts by mass of precipitated silica, and mix them at a speed of 20 r / min to obtain a mixture;

[0056] Step 2-1. At a rotation speed of 20 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 70°C and -0.08 mPa, cool to room temperature after drying, and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 7wt%.

[0057] In order to verify the effects of the key components of the present invention, based on Example 2, the key components are omitted or replaced, as follows:

[0058] Preparation of Comparative Example 1:

[0059] 1. Preparation of potassium chloride granules with sustained-release agent

[0060] Step 1-1. Accurately weigh 25 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 85°C and 100 r / min for 20 min to obtain gelatinized starch;

[0061] Step 1-2. Mix 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol, 6.7 parts by mass of glyoxal and 6 parts by mass of genipin, add the mixture to the gelatinized starch, and stir the mixture at 67° C. and 150 r / min for 100 min to obtain a sustained-release agent.

[0062] 2. Preparation of potassium chloride slow-release fertilizer

[0063] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix them at a speed of 15 r / min to obtain a mixture;

[0064] Step 2-2. At a rotation speed of 15 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 67°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6wt%.

[0065] That is, compared with Example 2, the peanut shell phenol liquefied product in step 1-2 is omitted, and the rest is consistent with Example 2.

[0066] Preparation of Comparative Example 2:

[0067] 1. Preparation of potassium chloride granules with sustained-release agent

[0068] Step 1-1. Accurately weigh 25 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 85°C and 100 r / min for 20 min to obtain gelatinized starch;

[0069] Step 1-2. Mix 5 parts by mass of peanut shell phenol liquefact, 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol, 6.7 parts by mass of glyoxal, and 6 parts by mass of genipin, add the mixture to the gelatinized starch, and stir the mixture at 67° C. and 150 r / min for 100 min to obtain a sustained-release agent.

[0070] 2. Preparation of potassium chloride slow-release fertilizer

[0071] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix them at a speed of 15 r / min to obtain a mixture;

[0072] Step 2-2. At a rotation speed of 15 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 67°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6wt%.

[0073] That is, compared with Example 2, the mass fraction of the peanut shell phenol liquefied product in step 1-2 is reduced to 5, and the rest is consistent with Example 2.

[0074] Preparation of Comparative Example 3:

[0075] 1. Preparation of potassium chloride granules with sustained-release agent

[0076] Step 1-1. Accurately weigh 25 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 85°C and 100 r / min for 20 min to obtain gelatinized starch;

[0077] Step 1-2. Mix 25 parts by mass of peanut shell phenol liquefied product, 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol, 6.7 parts by mass of glyoxal, and 6 parts by mass of genipin, add the mixture to the gelatinized starch, and stir the mixture at 67° C. and 150 r / min for 100 min to obtain a sustained-release agent.

[0078] 2. Preparation of potassium chloride slow-release fertilizer

[0079] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix them at a speed of 15 r / min to obtain a mixture;

[0080] Step 2-2. At a rotation speed of 15 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 67°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6wt%.

[0081] That is, compared with Example 2, the mass fraction of the peanut shell phenol liquefied product in step 1-2 is increased to 25, and the rest is consistent with Example 2.

[0082] Preparation of Comparative Example 4

[0083] 1. Preparation of potassium chloride granules with sustained-release agent

[0084] Step 1-1. Accurately weigh 25 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 85°C and 100 r / min for 20 min to obtain gelatinized starch;

[0085] Step 1-2. 10 parts by mass of peanut shell phenol liquefact, 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol and 12.7 parts by mass of glyoxal are mixed and added to the gelatinized starch, and stirred at 67° C. and 150 r / min for 100 min to obtain a sustained-release agent.

[0086] 2. Preparation of potassium chloride slow-release fertilizer

[0087] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix them at a speed of 15 r / min to obtain a mixture;

[0088] Step 2-2. At a rotation speed of 15 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 67°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6wt%.

[0089] That is, compared with Example 2, the genipin in step 1-2 is missing, and the missing amount is supplemented with an equal amount of glyoxal, and the rest is consistent with Example 2.

[0090] Preparation of Comparative Example 5

[0091] 1. Preparation of potassium chloride granules with sustained-release agent

[0092] Step 1-1. Accurately weigh 25 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 85°C and 100 r / min for 20 min to obtain gelatinized starch;

[0093] Step 1-2. 10 parts by mass of peanut shell phenol liquefied product, 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol and 12.7 parts by mass of genipin are mixed and added to the gelatinized starch, and stirred at 67° C. and 150 r / min for 100 min to obtain a sustained-release agent.

[0094] 2. Preparation of potassium chloride slow-release fertilizer

[0095] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix them at a speed of 15 r / min to obtain a mixture;

[0096] Step 2-2. At a rotation speed of 15 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 67°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6wt%.

[0097] That is, compared with Example 2, the glyoxal in step 1-2 is missing, and the missing amount is supplemented with an equal amount of genipin, and the rest is consistent with Example 2.

[0098] Preparation of Comparative Example 6

[0099] 1. Preparation of potassium chloride granules with sustained-release agent

[0100] Step 1-1. Accurately weigh 25 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 85°C and 100 r / min for 20 min to obtain gelatinized starch;

[0101] Step 1-2. 10 parts by mass of peanut shell phenol liquefied product, 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol, 3 parts by mass of glyoxal, and 9.7 parts by mass of genipin are mixed and added to the gelatinized starch, and stirred at 67° C. and 150 r / min for 100 min to obtain a sustained-release agent.

[0102] 2. Preparation of potassium chloride slow-release fertilizer

[0103] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix them at a speed of 15 r / min to obtain a mixture;

[0104] Step 2-2. At a rotation speed of 15 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 67°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6wt%.

[0105] That is, compared with Example 2, the mass ratio of glyoxal to genipin in step 1-2 is adjusted to 3:9.7, and the rest is consistent with Example 2.

[0106] Preparation of Comparative Example 7

[0107] 1. Preparation of potassium chloride granules with sustained-release agent

[0108] Step 1-1. Accurately weigh 25 parts by mass of cassava starch, mix the cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir and gelatinize at 85°C and 100 r / min for 20 min to obtain gelatinized starch;

[0109] Step 1-2. Mix 10 parts by mass of peanut shell phenol liquefied product, 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol, 9.7 parts by mass of glyoxal, and 3 parts by mass of genipin, add the mixture to the gelatinized starch, and stir the mixture at 67° C. and 150 r / min for 100 min to obtain a sustained-release agent.

[0110] 2. Preparation of potassium chloride slow-release fertilizer

[0111] Step 2-1. Take 500 parts by mass of potassium chloride particles and place them in a rotating drum, preheat them to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix them at a speed of 15 r / min to obtain a mixture;

[0112] Step 2-2. At a rotation speed of 15 r / min, use a spray gun to evenly spray the slow-release agent obtained in step 1-2 onto the surface of the mixture obtained in step 2-1, so that the surfaces of all potassium chloride particles are coated with the slow-release agent, and then vacuum dry the coated particles at 67°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6wt%.

[0113] That is, compared with Example 2, the mass ratio of glyoxal to genipin in step 2-2 is adjusted to 9.7:3, and the rest is consistent with Example 2.

[0114] Performance Testing

[0115] 1 Mechanical properties test

[0116] The sustained-release agent was heated to 73°C for thermal cross-linking for 30 minutes, then poured onto a polytetrafluoroethylene plate to form a film, and dried in an electric blast drying oven at 67°C until it was free of water. The sustained-release film was removed and its tensile strength was measured on a universal material testing machine according to the test method of the national standard GB / T 1040.1-2018 "Determination of tensile properties of plastics". The tensile rate was 50 mm / min. The results are shown in Table 1.

[0117] 2. Determination of sustained release performance

[0118] The 24h initial release rate and 30d release rate of potassium in the samples were determined according to the experimental method of GB / T 23348-2009 "Slow-release fertilizers". The results are shown in Table 2 and Figure 1 .

[0119] Table 1 Tensile strength of the film formed by the sustained-release coating agent

[0120] Group Tensile strength / mPa Example 1 8.8 Example 2 8.9 Example 3 8.6 Comparative Example 1 6.2 Comparative Example 2 6.5 Comparative Example 3 6.8 Comparative Example 4 6.3 Comparative Example 5 5.3 Comparative Example 6 5.6 Comparative Example 7 6.2

[0121] Table 2 Sustained release performance results

[0122]

[0123]

[0124] Result analysis:

[0125] 1. The key role of peanut shell phenol liquefact in sustained release performance

[0126] Compared with Example 2 containing peanut shell phenol liquefied material, the tensile strength of Comparative Example 1 omitting the peanut shell phenol liquefied material decreased by 30.34%, the 24-hour release rate increased from 3.5% to 7.3%, and the release period was shortened by 30 days, indicating that the peanut shell phenol liquefied material can form a hydrogen bond network with the hydroxyl groups of starch through its phenolic hydroxyl groups, thereby enhancing the cross-linking density of the sustained-release membrane, thereby improving the tensile strength and sustained-release performance of the sustained-release membrane. In addition, the 30-day release rate of Comparative Example 1 is as high as 50.7%, and the 30-day release rate of Example 2 is 17.4%, indicating that the peanut shell liquefied material has a certain hydrophobic barrier function, and the lignin-derived aromatic ring structure of the peanut shell liquefied material gives the membrane hydrophobicity, reduces the water penetration rate, and has a blocking effect on the sustained-release channel.

[0127] It can be seen from Comparative Examples 2 and 3 that with the increase in the amount of peanut shell phenol liquefied material, the release performance of the sustained-release membrane is improved (24h release rate 6.2%→5.9%), but both are inferior to Example 2, indicating that the amount of peanut shell phenol liquefied material added in the formula will affect the performance of the sustained-release membrane, and too low or too high an amount of peanut shell phenol liquefied material is not conducive to improving the performance of the sustained-release membrane.

[0128] 2. Glyoxal-genipin synergistic cross-linking mechanism

[0129] Double cross-linking system (Comparative Examples 4-7)

[0130] According to Example 2 and Comparative Examples 4-5, the use of glyoxal or genipin alone leads to a significant decrease in performance, indicating that glyoxal and genipin have a synergistic effect. This may be because the aldehyde group of glyoxal forms a hemiacetal bond with the hydroxyl group of starch to achieve rapid cross-linking, and the cyclopentadiene glycoside group of genipin constructs a stable and long-lasting cross-linked network through addition reaction.

[0131] In Example 2, the mass ratio of glyoxal to genipin is 6:6.7, and the tensile strength reaches 8.9 mPa. When the ratio of the two is unbalanced to 3:9.7 (Comparative Example 6) or 9.7:3 (Comparative Example 7), the tensile strength decreases by 37.08% and 30.34%, respectively, and the release period is shortened to 50 / 80 days, indicating that glyoxal-genipin can meet the requirements of rapid curing and long-term stability within a certain dosage ratio range.

[0132] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A sustained-release agent for potassium chloride granules, characterized in that: The sustained-release agent comprises the following raw materials by weight: 20-30 parts of starch; 10-13 parts of peanut shell phenol liquefied material; Glycerin 4.5-6 parts; 4-8 parts of polyvinyl alcohol; Crosslinking agent 11-13.5 parts.

2. The sustained-release agent for potassium chloride granules according to claim 1, characterized in that: The starch is selected from at least one of cassava starch, sweet potato starch and potato starch.

3. The sustained-release agent for potassium chloride granules according to claim 2, characterized in that: The starch is selected from tapioca starch.

4. The sustained-release agent for potassium chloride granules according to claim 1, characterized in that: The cross-linking agent is selected from at least one of glyoxal and genipin.

5. The sustained-release agent for potassium chloride granules according to claim 3, characterized in that: The cross-linking agent is composed of glyoxal and genipin in a mass ratio of (6-6.5):(5-7).

6. Use of the slow-release agent for potassium chloride granules according to any one of claims 1 to 5 in the preparation of potassium chloride slow-release fertilizer.

7. The method for preparing the sustained-release agent for potassium chloride granules according to claim 5, characterized in that: The preparation method comprises the following steps: Step 1-1. Accurately weigh cassava starch, mix cassava starch with deionized water at a solid-liquid ratio of 1:6 g / mL, and stir at 80-90°C and 50-100 r / min for 20 min to obtain gelatinized starch; Step 1-2. Mix the formulated amount of peanut shell phenol liquefied product, glycerol, polyvinyl alcohol, glyoxal and genipin, add them to the gelatinized starch, stir and react at 65-70° C. and 100-200 r / min for 90-120 minutes to obtain a sustained-release agent.

8. A method for preparing a potassium chloride slow-release fertilizer, characterized in that: The preparation method comprises the following steps: Step 2-1. Place potassium chloride particles in a rotating drum, preheat to 70-75°C, add microcrystalline wax and precipitated silica, and mix at a speed of 10-20 r / min to obtain a mixture, wherein the mass ratio of the potassium chloride particles, microcrystalline wax and precipitated silica is 500:(3-4):(3-5); Step 2-2. At a rotation speed of 10-20 r / min, use a spray gun to evenly spray the slow-release agent described in any one of claims 1-5 onto the surface of the mixture obtained in step 2-1, so that the surface of all potassium chloride particles is coated with the slow-release agent, and then vacuum dry the coated particles at 65-70°C and -0.08 mPa, cool to room temperature after drying, and sieve to obtain the potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 5-7wt%.

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