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Home / News / Industry News / Label Ink Adhesion Normal at Printing — Why Does It Shed After Refrigeration?
Industry News
Food Labels · Beverage Packaging · Daily Chemical Labels · Medical Labels
In food label, beverage packaging, daily chemical label, and medical label printing, a consistent pattern is encountered: the label has normal adhesion immediately after printing, all tests meet requirements — but after cold storage or freezing, the ink begins to shed, peel, or can be separated from the substrate even by light scratching.
In most cases, this is not caused by the ink itself. The problem is the combined result of adhesion system, substrate characteristics, environmental change, and formulation matching acting together.
1 · Ambient-Temperature Adhesion ≠ Cold Storage Stability
After printing is complete: ink adhesion is normal, film appearance is complete, ambient-temperature testing meets requirements. But these only indicate stable performance under ambient conditions — they cannot guarantee the same adhesion effect after entering cold storage or freezing environments.
2 · Low Temperature Changes Material State
After entering the cold storage environment: temperature drops, substrate contracts, and the ink layer also changes accordingly. If the dimensional change of ink and substrate is not synchronised, interfacial stress gradually increases and adhesion may decline.
3 · Condensation Water Affects Adhesion Performance
When products are taken from a cold environment, water vapour in the air readily forms condensation on the label surface. Long-term exposure to cold-warm cycling: moisture continuously penetrates the interface, local bonding strength decreases, and ink becomes more prone to shedding. Cold environments therefore test not only low-temperature resistance but also moisture resistance.
4 · Different Label Materials Behave Differently
Common label materials — PET, PP, PE, synthetic paper, coated paper — differ in surface energy, shrinkage rate, and low-temperature resistance. Even using the same ink, final performance may differ significantly across substrates.
5 · Ink System Determines Low-Temperature Durability
Beyond substrate, the ink system is equally critical. If resin-substrate compatibility is insufficient, the adhesion system is incomplete, or flexibility is poor — adhesion decline and ink shedding are more likely in low-temperature environments.
6 · Why Fine at Delivery but Shedding After Refrigeration?
Because when the product leaves the factory: the ink is cured, ambient adhesion is normal, and appearance has no abnormality. After cold storage, transport, and cold-warm cycling: materials continuously contract and expand, interfacial stress continuously changes, and adhesion performance gradually declines — hidden problems gradually reveal themselves.
Summary
Label ink shedding after cold storage is fundamentally the combined result of low-temperature environment, cold-warm cycling, substrate characteristics, and ink adhesion system acting together. When analysing cold-storage ink shedding, beyond the ink itself, substrate type, adhesion system, additive matching, and actual service environment all need comprehensive evaluation to improve long-term label stability in cold environments.
Ambient-temperature pass ≠ cold storage stability
Low temperature changes ink and substrate state
Condensation weakens interfacial bonding
Substrate type affects cold-temperature adhesion
Ink system determines low-temperature durability
Cold-warm cycling reveals latent adhesion problems
Frequently Asked Questions
Is there a standard test for label ink cold storage adhesion resistance?
Several test methods are used across the industry: direct cold storage adhesion testing (peel or cross-cut after defined cold storage period), thermal shock cycling (multiple rapid transitions between cold and ambient temperatures), and condensation resistance testing (subjecting labels to condensation conditions then immediately testing adhesion). The specific method and pass criteria should be matched to the product's actual cold chain conditions and customer specification requirements.
Does the ink cure level affect cold storage adhesion performance?
Yes significantly. Under-cured ink has lower crosslink density and cohesive strength than a fully cured equivalent — making it more vulnerable to the combination of low temperature embrittlement and interfacial stress that causes cold-storage shedding. Ensuring complete cure before cold chain exposure is an important baseline requirement, even when the formulation is otherwise well-matched for cold-temperature performance.
