Double-layer coated fertilizer and preparation method thereof

Abstract

The invention discloses a double-layer coated fertilizer and a preparation method thereof. The double-layer coated fertilizer is composed of a core fertilizer, and an inner-layer coating material and an outer-layer coating material both covering the core fertilizer; the inner-layer coating material is microcrystalline wax; the outer-layer coating material comprises a water-retaining agent and a coating agent; the mass ratio of the core fertilizer, the inner-layer coating material and the outer-layer coating material is 100:(0.5-2):(3-20); the mass ratio of the water-retaining agent to the coating agent is 100:(5-30). The preparation method comprises the following steps: adding the core fertilizer and the inner-layer coating material to a coating machine, blasting air and heating until the inner-layer coating material is melted to cover the core fertilizer, thereby obtaining the fertilizer covered with the inner-layer coating material; 2) covering the fertilizer covered with the inner-layer coating material with the outer-layer coating material for at least once, thereby obtaining the double-layer coated fertilizer. The double-layer coated fertilizer has better controlled release and water retaining effects; the preparation method is simple; the coating agent is good in dissolving effect, and advantageous for coating; the production method is suitable for batch production.

Description

technical field [0001] The invention relates to a double-layer coated fertilizer and a preparation method thereof, belonging to the technical field of slow and controlled release fertilizers. Background technique [0002] Fertilizer and water are two crucial factors in agricultural production. According to statistics, fertilizer accounts for 50% of all agricultural production expenditures, is the largest material input in agricultural production, and is also an extremely critical factor for increasing crop production in the world. However, some studies have shown that the utilization rate of nitrogen fertilizer for major grain crops in my country varies from 10.8% to 40.5%, with an average of 27.5%, and the utilization rate of phosphorus fertilizer is even lower, which not only causes economic losses, but also seriously pollutes the environment. In addition, with my country's population growth, economic development and climate change, my country's agriculture, especially in...

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Problems solved by technology

However, in this application, the process of the inner layer of the coating is relatively complicated, and the operation is difficult. Moreover, the aqueous solution of potassium salt or ammonium salt is cross-linked with carrageenan powder to form a hydrogel, and its mechanical strength and film quality are difficult to control. Layers take longer to dry

In addition, the first method in this application is to directly add superabsorbent resin powder to wrap the outer layer of fertilizer particles after spraying the aqueous solution of potassium salt or ammonium salt to form the inner layer of the coating, without using binder or coating agent, so the coating It is difficult to control the thickness adjustment of the outer layer of the film; in the second method, a super absorbent resin solution is used as the outer coating material, so it is necessary to use a solvent with strong solubility (mostly toxic solvents), and in order to facilitate spraying, the solution is highly absorbent. The mass concentration of the resin should not be too large, which will greatly increase the amount of solvent required, which will hinder its mass production

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