Multilayer Polyurea-Polyurethane Coating for Controlled Urea Release
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Solution Overview
Problem
Existing coated urea-containing fertilizer particles require high layer thicknesses for long-term release, which is not suitable for all applications and increases costs, while the release profile is not optimal for prolonged fertilizer release.
Innovation Solution
A multilayer coating process involving the formation of a polyurea layer followed by a polyurethane layer on urea-containing fertilizer particles, with the polyurea layer acting as an adhesion promoter for the polyurethane layer, allowing for controlled release with lower coating thicknesses and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If high layer thicknesses of surface coating are used, then long-term fertilizer release is achieved, but manufacturing costs increase and the release profile becomes unsuitable for all applications
Solution Approach 1:
The coating is divided into two distinct layers: an inner polyurea layer and an outer polyurethane layer. This segmentation allows each layer to perform its specific function - the polyurea layer provides adhesion and controlled dissolution, while the polyurethane layer provides protective barrier properties. This functional division achieves effective long-term release with reduced total coating thickness compared to single-layer coatings.
Solution Approach 2:
The invention uses a composite coating structure combining polyurea and polyurethane materials. The polyurea layer (containing isocyanate and water) is applied first as an adhesion promoter, followed by the polyurethane layer. This composite structure leverages the complementary properties of both materials to achieve optimized release characteristics and reduced coating thickness requirements.
2Duration of action of moving object
If high layer thicknesses of surface coating are used, then long-term fertilizer release is achieved, but the coating complexity increases
Solution Approach 1:
The coating system is segmented into two functional layers applied in sequence. The inner polyurea layer is formed first through reaction of isocyanate with water, providing adhesion to the urea fertilizer core. The outer polyurethane layer is then applied over the polyurea layer. This segmentation creates a manageable two-step process that achieves superior release control compared to single-layer coatings of equivalent or greater thickness.
3Ease of manufacture
If single-layer coating is used, then manufacturing process is simple, but release profile is not suitable for prolonged fertilizer release
Solution Approach 1:
The coating function is segmented between two layers: the inner polyurea layer handles adhesion and controlled dissolution, while the outer polyurethane layer provides protective barrier properties. This segmentation enables prolonged release control that cannot be achieved with single-layer coatings, while the multi-layer structure remains manufacturable through a systematic two-step application process.
Solution Approach 2:
The invention employs a composite coating system combining polyurea and polyurethane materials with complementary properties. The polyurea layer provides adhesion promotion and controlled dissolution characteristics, while the polyurethane layer adds protective barrier properties. This composite structure achieves optimized prolonged release profiles that single-layer coatings cannot provide.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables a slow and controlled release of urea-containing fertilizers over a prolonged period, achieving a long-term effect with significantly lower layer thicknesses and costs, compared to traditional single-layer coatings.
Implementation Method 1
the urea-containing fertilizer, after moistening, can be reacted with an isocyanate component in order to form a polyurea layer on the fertilizer particle
Implementation Method 2
forming at least one polyurethane layer on the at least one polyurea layer on the urea-containing fertilizer
Implementation Method 3
the polyurea layer acting as an adhesion promoter for the polyurethane layer
Implementation Method 4
These are typically granular, at least partly water-soluble urea-containing fertilizer particles encased by a water-insoluble but water-permeable layer. By means of the encasing, it is possible to control the dissolution rate of the fertilizer particles
Data Source
AI summary
A process for producing coated urea-containing fertilizer particles, comprising the following steps:A) forming at least one polyurea layer on the uncoated urea-containing fertilizer, and thenB) forming at least one polyurethane layer on the at least one polyurea layer on the urea-containing fertilizer.