One-component self-crosslinking waterborne polyurethane sustained and controlled release coating material

Abstract

The invention discloses a single-component self-crosslinking waterborne polyurethane sustained / controlled release coated material and a preparation technology thereof, and belongs to the technical field of macromolecule material preparation. The preparation technology is characterized by including the steps that first, diisocyanate, castor oil, oligomer polyols and chain extends are used for preparing waterborne polyurethane, then the waterborne polyurethane and a polyurethane crosslinking agent closed by sodium hydrogen sulfite are evenly mixed, and then the single-component self-crosslinking waterborne polyurethane sustained / controlled release coated material is obtained. With water being a carrier, the obtained coated material does not contain organic solvent and is environmentally friendly and free of pollution, through adjusting the content of the castor oil and a hard and soft section proportion, the crosslinking degree and hydrophily of the coated material can be adjusted and controlled, then the release rate of nutrients is controlled, carboxyl and other active groups in the coated material can activate phosphorus elements in soil, increase the utilization rate of the phosphorus elements and fix potassium ions in the soil, and then the utilization rate of fertilizer is greatly increased.

Description

technical field [0001] The invention relates to the technical field of preparation of polymer materials, in particular to a single-component self-crosslinking waterborne polyurethane slow-controlled release coating material and a preparation process thereof. Background technique [0002] my country is a large agricultural country, and chemical fertilizers play a very important role in agricultural production. At present, my country's chemical fertilizers are mainly quick-acting fertilizers. Due to leaching and volatilization in the soil, a large amount of nutrients are lost. Farmers want to increase crop yields. The amount of chemical fertilizers had to be greatly increased. From the average fertilization rate of a few kilograms per mu in the 1960s to the current rate of 40 kg / mu, the amount of fertilizer per mu increased by more than 6 times in just a few decades. Internationally, it is more than twice the upper limit of 15kg / mu of chemical fertilizers allowed. According to ...

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Problems solved by technology

[0003] The slow and controlled release fertilizers currently on the market mainly fall into the following three categories: 1. Steady-state fertilizers added with urease inhibitors and nitrification inhibitors, which can delay the hydrolysis of urea and reduce the rate of conversion of ammonium nitrogen into nitrate nitrogen , but the improvement effect on fertilizer utilization rate is not obvious; 2. Inorganic mineral salt coated fertilizers, such as sulfur-coated urea, due to poor sealing of such coating materials, the film layer is relatively brittle and easy to fall off, so the slow and controlled release effect is not good. In addition, long-term use of sulfur-coated urea is likely to cause soil acidification; 3. Polymer coated fertilizers mainly use urea-formaldehyde resin, epoxy polyester, polystyrene, polyethylene, polyvinyl chloride, etc. as coating agents, of which urea-formaldehyde Resin coating technology is the most mature and widely used, but the resin will decompose formaldehyde in the soil, which is easy to cause damage to crops and soil. At the same time, the above coating materials must be dissolved with a certain amount of organic solvent before use. And it is not easy to degrade in the soil, so it is easy to cause pollution to the environment, and it is easy to damage the soil structure after long-term use

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