Biodegradable Polymer Coatings for Controlled-Release Fertilizer Granules

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Solution Overview

Problem

Existing polymer-coated fertilizers are not biodegradable, leading to environmental issues and inefficient nutrient release, and compositions with Lewis acids can alter soil chemistry.

Innovation Solution

A coated fertilizer granule with a core containing plant nutrients and a coat made of specific ratios of poly butylene succinate adipate (PBSA) and poly lactic acid (PLA) or poly butylene succinate (PBS), optionally with wax, ensuring complete degradation into carbon dioxide and water within two years under ambient conditions, meeting OK Biodegradable SOIL certification criteria.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If polymer coating is used for controlled release of nutrients, then nutrient release control is improved, but biodegradability deteriorates

Engineering Contradiction:

Improvecontrolled release durationVSAvoidenvironmental harm from non-biodegradable polymers

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the polymer coating by specifying precise weight percentages of PBSA (55-90%), second polymer (10-45%), and wax (0-30%). This parameter optimization enables the coating to achieve both controlled release functionality and complete biodegradability within two years, resolving the contradiction between duration control and environmental harm.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polymer coating material combining PBSA, a second polymer (PLA and/or PBS), and optionally wax. This composite formulation leverages the biodegradability of all components while maintaining controlled release properties, thus achieving both extended nutrient release and environmental compatibility.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If higher content of PBSA is used, then biodegradability is improved, but controlled release performance deteriorates

Engineering Contradiction:

ImprovebiodegradabilityVSAvoidcontrolled release performance

Core Design Contradiction:

Object-affected harmful factorsVSDuration of action of moving object

Solution Approach 1:

The patent establishes optimal parameter ranges for PBSA content (55-90 wt.%) and second polymer content (10-45 wt.%) to balance biodegradability and controlled release performance. This quantitative parameter control ensures the coating degrades at an appropriate rate while maintaining nutrient release control, preventing both excessive degradation and prolonged retention.

Inventive Principle:

Principle #35Parameter changes

3Duration of action of moving object

If lower content of PBSA is used, then controlled release performance is improved, but biodegradability deteriorates

Engineering Contradiction:

Improvecontrolled release performanceVSAvoidbiodegradability

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent sets the minimum PBSA content at 55 wt.% to ensure sufficient biodegradability while maintaining controlled release functionality. This lower bound parameter specification prevents the coating from becoming too resistant to degradation, ensuring complete biodegradation within two years while preserving nutrient release control.

Inventive Principle:

Principle #35Parameter changes

4Object-affected harmful factors

If Lewis acid is used to enhance polymer degradation, then biodegradability is improved, but soil chemistry is altered

Engineering Contradiction:

Improvepolymer degradation rateVSAvoidsoil chemistry alteration

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent removes Lewis acids from the fertilizer composition entirely, replacing them with inherently biodegradable polymer materials (PBSA, PLA, PBS) that degrade through natural biological processes. This extraction of the harmful component eliminates soil chemistry alteration while maintaining enhanced biodegradability through proper polymer selection and formulation.

Inventive Principle:

Principle #2Taking out (Extraction)

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 granule provides controlled release of nutrients, fully degrading in soil within two years and avoiding environmental harm, while maintaining soil health and nutrient balance.

Implementation Method 1

the polymers in the coating layer can degrade fully or at least more than 90 % by weight into carbon dioxide and water within two years in soil under ambient conditions

Methodology Applied

Scientific EffectBiodegradation: Decomposition (biological)

Data Source

PatentEP4208433B1Coated fertilizer granules

Publication Date: 2025.10.15 SABIC AGRI NUTRIENTS CO

Figure 1A~1D
Figure 2

AI summary

A fertilizer granule containing a core containing a plant nutrient; and a coat containing 55 wt. % to 90 wt. % of a poly butylene succinate adipate (PBSA), 10 wt. % to 45 wt. % of a second polymer selected from poly lactic acid (PLA), poly butylene succinate (PBS), or a combination or blend of PLA and PBS, and 0 wt. % to 30 wt. % of a wax based on the total weight of the coat, the coat forming a coating on an outer surface of the core and methods of making and using the fertilizer granule. Also a coating composition containing 55 wt. % to 90 wt. % of a PBSA and 10 wt. % to 45 wt. % of a second polymer selected from PLA, PBS, or a combination or a blend of PLA and PBS, and 0 wt. % to 30 wt. % of a wax.