Toughening method of sulphur-coated controlled-release fertilizer

Abstract

The invention relates to a method for toughening sulfur-coated controlled-release fertilizer, comprising the following steps: (1) uniformly mixing epoxy resin and toughening agent to obtain a toughening resin premix; (2) making the toughening resin premix Mix evenly with the curing agent to prepare a mixed solution; (3) spray liquid sulfur on the surface of the core fertilizer to obtain sulfur-coated fertilizer particles; (4) spray the mixed solution on the surface of the sulfur-coated fertilizer particles to obtain toughened Sulfur controlled release fertilizer. The present invention uses carboxyl-terminated hyperbranched polyester HBP-SA or carboxyl-terminated liquid nitrile rubber as a toughening agent. These two toughening agents can not only play a toughening role, but also enhance the sealing effect of the membrane material , to achieve the purpose of spraying the toughening resin on the sulfur-coated controlled-release fertilizer without spraying the sealing agent, thereby reducing the spraying steps.

Description

technical field [0001] The invention relates to a method for toughening sulfur-coated controlled-release fertilizers, which belongs to the technical field of controlled-release fertilizer production. Background technique [0002] Sulfur-coated controlled-release fertilizer is to coat a layer of about 20μm sulfur film on the surface of urea or compound fertilizer particles, and then apply a sealant to slow down the release rate of the fertilizer. At the same time, the release period of the fertilizer can be controlled through the difference in the thickness of the sulfur-coated fertilizer. Generally, it can be controlled within 1 to 4 months. If the sulfur-coated controlled-release fertilizer is coated with a layer of resin, the controlled-release period can reach 12 months. [0003] For example, Chinese patent document CN1569774A (application number 200410024050.x) discloses a film-coated controlled-release fertilizer that uniformly coats a thermosetting polymer resin on sul...

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Problems solved by technology

[0005] The problem with the above-mentioned technology is that the brittleness of sulfur is relatively large after solidification, and the sulfur film about 20 μm on the surface of the fertilizer particles is easily damaged by external force, resulting in serious shelling of the sulfur-coated controlled-release fertilizer, which affects the controlled-release effect of the sulfur-coated controlled-release fertilizer. In the existing production process, the thermosetting resin, microcrystalline wax or epoxy resin coated on the outside of the sulfur film can alleviate this problem, but there is still shelling phenomenon, which affects the use effect of controlled release fertilizer

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