Abstract

This disclosure presents a coating technology incorporating irreversible photochromic pigments microencapsulated within polymer shells and dispersed in industrial binder matrices (acrylics, epoxies, polyurethanes, vinyls). Upon cumulative ultraviolet (UV) exposure, the encapsulated pigments undergo non-reversible molecular rearrangements, producing a permanent hue shift. The pigment system is tuned to absorb predominantly in the UVB (280–315 nm) and near-UVA (315–340 nm) spectral bands, which are most strongly correlated with photodegradation of polymers.

Encapsulation (2–5 μm capsules) provides environmental stability against oxygen, humidity, and thermal cycling, ensuring reproducible performance across climates. The coatings are applied as thin topcoats (≈50 μm dry film thickness) via spray, dip, or powder-coat methods, compatible with construction substrates, marine hulls, polymer composites, and aerospace/drones.

The system is calibrated through accelerated weathering protocols, wherein colorimetric values (ΔE, CIE Lab*) are recorded in parallel with mechanical property measurements (tensile strength, hardness). Dose–response mapping enables correlation of visible shade progression (white→yellow→orange→red) with cumulative UV dosage (J/cm²) and material fatigue thresholds (e.g., ≥20% tensile loss).

Unlike prior art focused on dosimeter labels, inks, or reversible photochromics, this system delivers a structural, cumulative, and irreversible indicator of UV-induced degradation. Applications include safety helmets, scaffolding, playground structures, marine vessels, and drone housings, providing low-cost, intuitive, and permanent visual monitoring of material lifetime.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

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