A sustained-release agent for potassium chloride granules, and its preparation method and application

Abstract

The invention discloses a slow-release agent for potassium chloride granules, a preparation method and an application thereof, and specifically belongs to the technical field of fertilizer manufacturing. The slow-release agent comprises the following raw materials in parts by weight: 20-30 parts of starch, 10-13 parts of peanut shell phenol liquefact, 4.5-6 parts of glycerol, 4-8 parts of polyvinyl alcohol, and 11-13.5 parts of a cross-linking agent. The slow-release agent provided by the invention can effectively prolong the release time of potassium chloride, reduce the short-term release rate of potassium chloride, and the slow-release period can reach 110 days, thereby improving the utilization rate of potassium fertilizer by crops. The slow-release agent and the slow-release potassium fertilizer provided by the invention have simple preparation processes and can be applied on a large scale.

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 granules, a preparation method and an application thereof. Background Art

[0002] In agricultural production, fertilizers are key factors in improving soil fertility and promoting crop growth. Their type and performance have a direct impact on agricultural production efficiency. With the continuous advancement of modern agricultural technology and the increasing awareness of environmental protection, the fertilizer industry is developing towards higher efficiency, specialization, functionality, and greenness.

[0003] Potassium chloride, a key nutrient for plant growth, is widely used in various fertilizers. However, traditional potassium chloride granular fertilizers have several drawbacks during use, such as rapid nutrient release, low utilization rate, and frequent application. These issues limit their effectiveness and may have negative environmental impacts.

[0004] To improve the utilization rate of potassium chloride granular fertilizer and reduce nutrient loss, researchers have begun exploring slow-release technology for potassium chloride granules. Slow-release fertilizers control the rate of nutrient release to better match crop nutrient needs, thereby improving fertilizer utilization and reducing the frequency of fertilization. This technology not only reduces farmers' labor intensity but also helps reduce environmental pollution.

[0005] However, the existing preparation process of potassium chloride granular slow-release fertilizer is often complicated, involving multiple auxiliary materials and complex process steps, which not only increases production costs but may also 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 shortcomings of the existing technology, the present invention aims to provide a new type of slow-release agent for potassium chloride granules. Through specific raw materials and preparation methods, the slow release of potassium chloride granules is achieved, thereby improving the utilization rate of fertilizers, reducing nutrient loss, and reducing production costs and environmental pollution.

[0008] To achieve the above objectives, 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 starch;

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

[0012] 4.5-6 parts of glycerin;

[0013] 4-8 parts of polyvinyl alcohol;

[0014] Cross-linking agent 11-13.5 parts.

[0015] Preferably, the starch is selected from at least one of tapioca 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 the cassava starch with deionized water at a material-liquid ratio of 1:6 g / mL, and gelatinize 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 liquefact, glycerol, polyvinyl alcohol, glyoxal, and genipin and 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 speed of 10-20 r / min, use a spray gun to evenly spray the slow-release agent according to any one of claims 1-5 onto the surface of the mixture obtained in step 2-1, so that all the surfaces of the potassium chloride particles are coated with the slow-release agent, and then vacuum-dry the coated particles at 65-70°C and -0.08 mPa. After drying, cool to room temperature 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-term 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 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. Those skilled in the art should understand 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 embodiments are all conventional methods; the materials, reagents, etc. used are all commercially available unless otherwise specified; the percentages mentioned in the specific embodiments are all mass percentages unless otherwise specified.

[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 material-liquid ratio of 1:6 g / mL, and stir 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 liquefact, 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 were mixed and added to the gelatinized starch. The mixture was stirred at 65° C. and 100 r / min for 90 min 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 to 70°C, add 3 parts by mass of microcrystalline paraffin and 3 parts by mass of precipitated silica, and mix at a speed of 10 r / min to obtain a mixture;

[0042] Step 2-2. At a 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 all the surfaces of the potassium chloride particles are coated with the slow-release agent, and then vacuum-dry the coated particles at 65°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain a 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 material-liquid ratio of 1:6 g / mL, and stir 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 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 were mixed and added to the gelatinized starch, and stirred at 67°C and 150 r / min for 100 minutes 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 granules and place them in a rotating drum, preheat to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix at a speed of 15 r / min to obtain a mixture;

[0049] Step 2-2. At a 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 all the surfaces of the 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 a potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6 wt%.

[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 material-liquid ratio of 1:6 g / mL, and stir at 90 ° C and 100 r / min for 20 min to obtain gelatinized starch;

[0053] Step 1-2. 13 parts by mass of peanut shell phenol liquefact, 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 were mixed and added to the gelatinized starch, and stirred at 70°C and 200 r / min for 120 minutes 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 granules and place them in a rotating drum, preheat to 75°C, add 4 parts by mass of microcrystalline paraffin and 5 parts by mass of precipitated silica, and mix at a speed of 20 r / min to obtain a mixture;

[0056] Step 2-1. At a 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 all the surfaces of the potassium chloride particles are coated with the slow-release agent, and then vacuum-dry the coated particles at 70°C and -0.08 mPa. After drying, cool to room temperature and sieve to obtain a 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 material-liquid ratio of 1:6 g / mL, and stir at 85 ° C and 100 r / min for 20 min to obtain gelatinized starch;

[0061] Step 1-2. 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 were 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.

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

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

[0064] Step 2-2. At a 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 all the surfaces of the 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 a potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6 wt%.

[0065] That is, compared with Example 2, the peanut shell phenol liquefied product in step 1-2 was omitted, and the rest was 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 material-liquid ratio of 1:6 g / mL, and stir 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, then add them to the gelatinized starch, stir and react at 67°C and 150r / min for 100min 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 granules and place them in a rotating drum, preheat to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix at a speed of 15 r / min to obtain a mixture;

[0072] Step 2-2. At a 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 all the surfaces of the 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 a potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6 wt%.

[0073] That is, compared with Example 2, the mass parts of the peanut shell phenol liquefied product in step 1-2 are reduced to 5, and the rest are the same as 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 material-liquid ratio of 1:6 g / mL, and stir 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 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, then add the mixture to the gelatinized starch, stir and react at 67°C and 150 r / min for 100 minutes 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 granules and place them in a rotating drum, preheat to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix at a speed of 15 r / min to obtain a mixture;

[0080] Step 2-2. At a 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 all the surfaces of the 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 a potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6 wt%.

[0081] That is, compared with Example 2, the mass parts of the peanut shell phenol liquefied product in step 1-2 are increased to 25, and the rest are the same as 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 material-liquid ratio of 1:6 g / mL, and stir 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 were mixed and added to the gelatinized starch, and stirred at 67° C. and 150 r / min for 100 minutes 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 granules and place them in a rotating drum, preheat to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix at a speed of 15 r / min to obtain a mixture;

[0088] Step 2-2. At a 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 all the surfaces of the 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 a potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6 wt%.

[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 material-liquid ratio of 1:6 g / mL, and stir 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 liquefact, 5 parts by mass of glycerol, 6 parts by mass of polyvinyl alcohol, and 12.7 parts by mass of genipin were 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 granules and place them in a rotating drum, preheat to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix at a speed of 15 r / min to obtain a mixture;

[0096] Step 2-2. At a 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 all the surfaces of the 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 a potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6 wt%.

[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 material-liquid ratio of 1:6 g / mL, and stir 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 liquefact, 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 were mixed and added to the gelatinized starch, and stirred at 67°C and 150 r / min for 100 minutes 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 granules and place them in a rotating drum, preheat to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix at a speed of 15 r / min to obtain a mixture;

[0104] Step 2-2. At a 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 all the surfaces of the 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 a potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6 wt%.

[0105] That is, compared with Example 2, the mass ratio of glyoxal to genipin in step 1-2 was adjusted to 3:9.7, and the rest was 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 material-liquid ratio of 1:6 g / mL, and stir at 85 ° C and 100 r / min for 20 min to obtain gelatinized starch;

[0109] 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, 9.7 parts by mass of glyoxal, and 3 parts by mass of genipin were mixed and added to the gelatinized starch, and stirred at 67°C and 150 r / min for 100 minutes 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 granules and place them in a rotating drum, preheat to 73°C, add 3.5 parts by mass of microcrystalline wax and 4 parts by mass of precipitated silica, and mix at a speed of 15 r / min to obtain a mixture;

[0112] Step 2-2. At a 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 all the surfaces of the 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 a potassium chloride slow-release fertilizer, wherein the mass proportion of the slow-release agent in the potassium chloride slow-release fertilizer is 6 wt%.

[0113] That is, compared with Example 2, the mass ratio of glyoxal to genipin in step 2-2 was adjusted to 9.7:3, and the rest was 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 dry. 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. Sustained-release performance determination

[0118] The 24h initial release rate and 30d release rate of potassium of 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 to Example 2, which included peanut shell phenol liquefaction, Comparative Example 1, which omitted peanut shell phenol liquefaction, showed a 30.34% decrease in tensile strength, an increase in the 24-hour release rate from 3.5% to 7.3%, and a 30-day shortening of the release period. This indicates that peanut shell phenol liquefaction can form a hydrogen bond network between its phenolic hydroxyl groups and the hydroxyl groups of starch, enhancing the crosslinking density of the sustained-release membrane and thus improving the tensile strength and sustained-release performance of the membrane. Furthermore, the 30-day release rate of Comparative Example 1 was as high as 50.7%, while that of Example 2 was 17.4%, demonstrating that peanut shell liquefaction possesses a certain hydrophobic barrier function. The lignin-derived aromatic ring structure of peanut shell liquefaction imparts hydrophobicity to the membrane, reducing the water permeation rate and blocking the sustained-release pathway.

[0127] It can be seen from Comparative Examples 2 and 3 that with the increase in the amount of peanut shell phenol liquefact, 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 liquefact 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 liquefact 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 either glyoxal or genipin alone resulted in a significant decrease in performance, indicating that glyoxal and genipin had a synergistic effect. This may be because the aldehyde group of glyoxal formed a hemiacetal bond with the hydroxyl group of starch to achieve rapid cross-linking, and the iridoid glycoside group of genipin constructed 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 specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the 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, and such changes and modifications are intended to fall within the 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 in parts by mass: 20-30 parts starch; 10-13 parts of peanut shell phenol liquefact; 4.5-6 parts of glycerin; 4-8 parts of polyvinyl alcohol; 11-13.5 parts of cross-linking agent; The starch is selected from tapioca starch; The cross-linking agent is composed of glyoxal and genipin in a mass ratio of (6-6.5): (5-7); The preparation method of the sustained-release agent comprises the following steps: Step 1-1. Accurately weigh cassava starch, mix the cassava starch with deionized water at a material-liquid ratio of 1:6 g / mL, and gelatinize 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 liquefact, glycerol, polyvinyl alcohol, glyoxal, and genipin, then add them to the gelatinized starch, stir and react at 65-70° C. and 100-200 r / min for 90-120 minutes to obtain the sustained-release agent.

2. Use of the slow-release agent for potassium chloride granules according to claim 1 in the preparation of potassium chloride slow-release fertilizer.

3. A method for preparing a potassium chloride slow-release fertilizer, characterized in that: The preparation method comprises the following steps: Step 2-1. Potassium chloride granules are placed in a rotating drum, preheated to 70-75°C, microcrystalline wax and precipitated silica are added, and mixed at a speed of 10-20 r / min to obtain a mixture, wherein the mass ratio of the potassium chloride granules, microcrystalline wax, and precipitated silica is 500:(3-4):(3-5); Step 2-2. At a speed of 10-20 r / min, use a spray gun to evenly spray the slow-release agent according to claim 1 onto the surface of the mixture obtained in step 2-1, so that all the surfaces of the potassium chloride particles are coated with the slow-release agent, and then vacuum-dry the coated particles at 65-70°C and -0.08 mPa. After drying, cool to room temperature 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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