Degradable polymer filmcoated controlled release fertilizer, preparation thereof and special filmcoated material

Abstract

The invention discloses a polymer coated released fertilizer and a preparation method thereof and a special coating material thereof. The coating material comprises isocyanate, polyol, degradable functional monomer, an aid agent of coating and a chain extender, wherein, the mol ratio between the isocyano group in the isocyanate and the hydroxyl group in the polyol is 1:2 to 2:1 and the mass of the degradable functional monomer is 1 percent to 20 percent of the mass of the coating material. The coated released fertilizer provided by the invention consists of a core and a karyotheca, wherein, the core is granule fertilizer and the karyotheca is prepared from the coating material, and the mass of the karyotheca is 2 percent to 10 percent of the mass of the core. The coating material has goodfilm forming and water resisting performance and can be degraded in nature. The hardness and the elasticity of the material can be adjusted by changing the mixure ratio of the coating material so as to prepare released fertilizers with different releasing periods.

Description

technical field [0001] The invention relates to a novel degradable polymer-coated controlled-release fertilizer, a preparation method and a special coating material. Background technique [0002] my country is a large agricultural country, and the proportion of chemical fertilizers in agricultural production investment accounts for about 50%, but the utilization rate of fertilizers in our country is only 30%, which causes a huge waste of economic energy and various environmental problems. Therefore, controlled-release fertilizers have become the development direction of agricultural fertilizers in the future, and polymer-coated fertilizers are called real controlled-release fertilizers by relevant experts. It uses polymer materials to form a film on the surface of fertilizers, controls the dissolution rate of fertilizers in the soil, and makes the dissolution rate consistent with the growth needs of plants, so as to save fertilizers, improve fertilizer utilization and increa...

AI Technical Summary

Problems solved by technology

[0006] Although a lot of research has been done on polyurethane thermosetting resin coating materials, there are still some problems that have not been completely resolved in the process of use: the mixing degree of isocyanate components and polyol components on fertilizer particles is low, the coating The utilization rate of raw materials is low; due to the increase of the viscosity of the monomer raw materials during the transition from liquid to solid state, and because there is no anti-adhesive effect of the solvent, after the monomer raw materials are evenly coated on the granular fertilizer, they will be in the solidification process. There are macroscopic defects such as tearing, pinholes, and poor uniformity, which seriously affect the controlled release performance

The various measures mentioned in the Chinese patent applied by Nick P.Wynnyk et al. to adopt staged curing and minimize the contact in the fertilizer curing stage have greatly improved the integrity of the coating process, but the existing process is relatively complicated. However, it does not advocate sufficient mixing of polyurethane raw materials before reaching the fertilizer, thereby reducing the uniformity of the chemical composition of the coating material. Therefore, relying on the contact between fertilizers on the fertilizer particles makes the two types of polyurethane raw materials Mixing, the degree of mixing is limited, it is bound to affect the film performance of the final film

[0007] On the other hand, due to the high chemical stability of polyurethane materials, if such controlled-release fertilizers are widely used in field crops, the problem that must be solved is the biodegradability of the coating materials

Because if the membrane material that is difficult to degrade is used for a long time, the residual membrane material will inevitably bring serious environmental problems to the soil.

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