Bio-based Polyurethane Coating for Controlled Release Fertilizer
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Solution Overview
Problem
Current polyurethane coating materials for controlled release fertilizers are costly, non-renewable, and have limited bio-based content, which hinders their widespread application in agricultural production due to high petroleum-based isocyanate usage and slow biodegradation.
Innovation Solution
A fully bio-based coating material is developed using bio-based polyol and 1,5-pentane diisocyanate compounds, with a high bio-based content of 65-71%, providing high biocompatibility, biodegradability, and improved mechanical properties through cross-linking, suitable for mass production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If petroleum-based isocyanate (MDI) is used to prepare polyurethane coating material, then the coating material has good mechanical strength and elasticity, but the cost increases and biodegradability decreases
Solution Approach 1:
The patent changes the chemical composition parameters by replacing petroleum-based MDI with bio-based 1,5-pentane diisocyanate (PDI) and using bio-based polyols (polyester and polyether types) with specific hydroxyl values and molecular weights. This parameter change achieves both good mechanical strength and biodegradability, as the bio-based PDI and polyols provide sufficient cross-linking density and network structure while being environmentally friendly and biodegradable.
Solution Approach 2:
The patent creates a composite coating material system combining bio-based PDI with multiple types of bio-based polyols (polyester polyols and polyether polyols) in specific ratios. This composite approach leverages the advantages of each component: PDI provides cross-linking and mechanical strength, while the different polyol types contribute to flexibility, biodegradability, and controlled release properties, achieving a balanced performance profile.
2Ease of operation
If polyether polyurethane materials are used, then the coating material has good elasticity and biodegradability, but the cost increases and biodegradation speed decreases
Solution Approach 1:
The patent uses a combination of polyether polyols and polyester polyols rather than relying solely on polyether polyols. This partial use of polyether polyols (providing biodegradability and elasticity) combined with polyester polyols (providing cost-effectiveness and hydrolysis resistance) achieves a balanced outcome where the coating material is sufficiently biodegradable without excessive cost increase, avoiding the need for pure polyether systems which are more expensive and slower to biodegrade.
3Ease of manufacture
If polyester polyurethane materials are used, then the coating material has low cost and good hydrolysis resistance, but the biodegradation speed decreases
Solution Approach 1:
The patent merges polyester polyols and polyether polyols in a coordinated formulation where polyester polyols provide cost-effectiveness and hydrolysis resistance, while polyether polyols contribute to biodegradability and elasticity. The combination creates a synergistic effect where the coating material maintains low cost and good stability from the polyester component while achieving acceptable biodegradation speed through the polyether component, overcoming the limitations of using either material alone.
4Stability of the object's composition
If crude MDI is used in the coating material preparation, then the coating material has good cross-linking density, but the environmental friendliness decreases
Solution Approach 1:
The patent replaces the persistent, non-biodegradable crude MDI with bio-based 1,5-pentane diisocyanate (PDI) that is designed to be environmentally friendly and biodegradable. The bio-based PDI maintains the necessary cross-linking density for coating integrity but decomposes more readily in the environment, aligning with the principle of using temporary, biodegradable materials that fulfill their function and then break down, eliminating long-term environmental persistence.
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
The bio-based coating material enhances the controlled release performance, wear resistance, and environmental safety of polyurethane controlled release fertilizers, offering a cost-effective and sustainable solution for agricultural applications.
Implementation Method 1
The coating material is prepared by cross-linking the bio-based polyol and the bio-based 1,5-pentane diisocyanate compound
Implementation Method 2
the fertilizer coating slowly releases nutrients by absorbing water to generate pressure
Data Source
AI summary
A curing agent isocyanate of a fully bio-based coating material for a polyurethane controlled release fertilizer is a bio-based 1,5-pentane diisocyanate compound. The bio-based 1,5-pentane diisocyanate compound is a compound of a bio-based 1,5-pentane diisocyanate monomer and its polymer, or a compound of different bio-based 1,5-pentane diisocyanate polymers. The bio-based PDI (1,5-pentane diisocyanate) polymer comprises a bio-based PDI trimer and its derivatives, a bio-based PDI tetramer and its derivatives, and other bio-based PDI multimers and their derivatives, which are derived from bio-based materials such as glucose and lysine. The mass percentage of bio-based materials in all raw materials is in a range of 65% to 71%. The coating material is prepared by cross-linking the bio-based polyol and the bio-based 1,5-pentane diisocyanate compound.