Slow/controlled-release fertilizer having water retention function and preparation method of slow/controlled-release fertilizer

Abstract

The invention relates to the field of slow / controlled-release fertilizers, and in particular relates to a slow / controlled-release fertilizer having a water retention function and a preparation methodof the slow / controlled-release fertilizer. The slow / release-fertilizer includes a fertilizer inner core and a coating material; and the coating material is formed by mixing an A material and a B material, wherein the A material includes a palm oil polyol, or includes a mixture formed by mixing the palm oil polyol and one or more selected from a polyester polyol and castor oil, the B material includes one of toluene diisocyanate, lysine diisocyanate and polymethylene polyphenyl polyisocyanate or a mixture formed by mixing of two or more selected from the toluene diisocyanate, the lysine diisocyanate and the polymethylene polyphenyl polyisocyanate. The preparation method comprises the steps of polishing the surface of the fertilizer inner core to be smooth, performing heating to 55-80 DEG C,spraying the A material and the B material, performing curing for a period of time, repeating the above step for 2-5 times, finally adding a certain amount of paraffin, and performing uniform rolling. According to the slow / controlled-release fertilizer having the water retention function and preparation method provided by the invention, the slow / controlled-release effects satisfy the growth requirements of plants, and the chemical fertilizer has a high utilization rate, high water retention performance and excellent biodegradability.

Description

technical field [0001] The invention relates to the field of slow and controlled release fertilizers, in particular to a slow and controlled release fertilizer with water retention function and a preparation method thereof. Background technique [0002] Water and fertilizers are the basic conditions for crop growth, and they are also important factors and resources that restrict the sustainable development of agriculture in our country. The current level of agricultural production in my country is low. The seasonal utilization rate of farmland chemical fertilizers is only 30-50% for nitrogen fertilizer, 10-20% for phosphorus fertilizer, and 35-50% for potassium fertilizer, which is about 5-20% lower than that of similar foreign fertilizers. Taking nitrogen fertilizer as an example, the annual loss of nitrogen is equivalent to more than 19 million tons of urea, equivalent to more than 38 billion yuan. On the other hand, my country is a country with poor water resources, and ...

AI Technical Summary

Problems solved by technology

[0005] However, these water-retaining slow-release fertilizers have multiple disadvantages at present: 1) there is a large gap in the water-absorbing and water-retaining properties between water-retaining slow-release fertilizers and water-absorbing and water-retaining materials, mainly because current fertilizers are generally electrolytes, which It has a great influence on the water absorption rate of superabsorbent resin

2) In the coating / wrapping method, the polymerization reaction in the coating process has a great influence on the properties of the fertilizer. For example, urea is prone to produce biuret under the effect of polymerization heat, which is toxic to crop seeds and seedlings; in addition , the presence of fertilizers also has a certain impact on the polymerization process of the resin and the polymer network structure

3) Physically adsorbed fertilizers are easy to gather on the surface of the particles during the drying process, and it is easy to produce a "burst release effect" during use

In addition, when the fertilizer has a great influence on the water absorption capacity of the superabsorbent resin, the amount of fertilizer combined with the resin is relatively low

4) Water-retaining slow-release fertilizers are difficult to store for a long time due to their water-absorbing and water-retaining properties

5) At present, there is a lack of theoretical research on the nutrient release mechanism and release kinetics of water-retaining slow-release fertilizers.

6) Use synthetic superabsorbent resin, which will remain in the soil due to its poor degradability. Long-term large-scale use must have a certain impact on the soil, while natural degradable superabsorbent resin has poor performance

7) The superabsorbent resin will form a gel in the soil, and its strength will be greatly reduced. As the coating layer, it is easy to have holes, so that the slow-release performance of nutrients is uneven and the ideal effect cannot be achieved.

[0007] The invention patent with the Chinese patent application number 201310753674.4 discloses a slow-release fertilizer coating material containing soybean oil polyol biodegradation and its preparation process. Although the equipment investment cost is small, the raw material cost is small, and the biodegradation rate meets the standard, However, the surface of the fertilizer solidifies into a dense and hard film with poor elasticity, and the coating material is prone to rupture after a period of time, which affects its water retention performance and slow and controlled release performance.

[0008] The invention patent with the Chinese patent application number 201410236023.2 discloses a controlled-release fertilizer coating material based on C36 dimerized fatty acid polyester polyol. Although it can be finally decomposed into carbon dioxide and water, it is non-toxic and non-polluting to the environment, but its The water retention performance is not excellent, so it is difficult to apply to plant cultivation in arid areas

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