The sealing performance of fertilizer packaging is a core indicator for ensuring product quality during storage and transportation. It directly determines whether the fertilizer will suffer from issues such as moisture absorption and caking, loss of efficacy due to volatilization, or leakage and contamination. Sealing designs, performance requirements, and testing standards vary significantly depending on the physical form of the fertilizer.
Sealing Methods by Packaging Type
Flexible Bags (for solid or water-soluble fertilizers): These typically utilize multi-layer composite structures-such as metallized (aluminized) films or PET/NY/PE laminates-with heat-sealed seams to provide a robust barrier against moisture and oxygen. Some self-sealing bags feature reclosable zippers, allowing for repeated access while maintaining a secure seal.
Rigid Bottles (for liquid fertilizers): These rely on precision-threaded caps that mate with the bottle neck, often incorporating internal silicone or rubber gaskets. Some designs utilize dual-gasket systems or locking mechanisms to structurally eliminate the risk of liquid leakage.
Woven Bags (for organic or large-volume solid fertilizers): These often feature an additional lamination layer to enhance overall barrier properties. Stitching is strictly controlled (with a stitch length of ≤1 cm), and valve openings are designed to fold and fit tightly, preventing powdered fertilizers from leaking through gaps.
Key Indicators of Sealing Performance
Barrier Properties: High-performance packaging should achieve a water vapor transmission rate (WVTR) of ≤10 g/m²·day and an oxygen transmission rate (OTR) of ≤50 cm³/m²·day·atm, significantly slowing down oxidation and moisture absorption.
Heat-Seal Strength: Compliant packaging must exhibit a heat-seal peel strength of ≥15 N/15mm, ensuring that seals do not crack or fail-leading to leakage-during stacking and transport.
Environmental Tolerance: Packaging must maintain its sealing integrity even after undergoing 10 temperature cycles (ranging from -20°C to 50°C) and exposure to high-humidity conditions (85% RH), ensuring reliability even in extreme environments.
