Photochromic Pigments UV Activated Color Changing

Technical Description

Photochromic pigments operate through a reversible photochemical reaction. The active component — in the KPMC-12 series, Avobenzone (Butyl Methoxydibenzoylmethane) functions within the photochromic system — undergoes a structural change when exposed to UV radiation, shifting its light absorption profile and producing a visible color change. When UV exposure stops, the molecule returns to its ground state and the color fades. The reaction is reversible and repeatable across many cycles, though long-term fatigue of the photochromic response does occur over time — a known characteristic of all organic photochromic systems, not specific to this product.

The pigment is microencapsulated or matrix-dispersed within a silica and inorganic salt carrier system (potassium nitrate, sodium nitrate, silica), which protects the active chemistry and allows dispersion into formulation systems. The fine particle size of 1–10 µm means the pigment integrates smoothly into inks and thin-film coatings without visible texture. The specific gravity of 1.20 ± 0.05 and melting point of 237–238°C are relevant parameters for processing: the melting point indicates the upper thermal limit for processes involving heat, such as masterbatch compounding or hot-melt applications.

The color change speed described — visible within approximately one second of direct sunlight exposure — reflects the general performance of organic photochromic systems under strong UV. Response time and intensity of color development are dependent on UV intensity, ambient temperature, and formulation matrix. Lower temperatures generally enhance photochromic response intensity; higher temperatures reduce it. This temperature dependency is a known characteristic of leuco-type and organic photochromic systems and should be factored into application design, particularly for outdoor coatings in warm climates.

Key Features & Benefits

Product Pictures

Applications

UV response intensity and activation speed vary with UV intensity, ambient temperature, and the formulation matrix. Evaluate under conditions representative of your end-use environment before finalizing grade selection.

Product Specifications

Example product shown. Full series data available upon request.

Full TDS and SDS available upon request. Multiple colors available across the KPMC series.Full TDS and SDS available upon request. Additional particle size grades available.

Industry Solutions

Photochromic pigments introduce two formulation challenges that standard colorants do not have. First, the active photochromic chemistry is sensitive to heat, pH, and certain solvents — the formulation matrix has to be compatible with the active component or the photochromic response degrades before the product reaches the end user. Second, the photochromic response itself — activation speed, color intensity, and fatigue resistance over repeated cycles — varies by grade and needs to match the specific conditions of the end-use environment. A pigment that performs well in a temperate European climate may show reduced response intensity in a high-ambient-temperature application in a warmer region, because photochromic response intensity is inversely related to temperature in most organic systems.

Kolortek Photochromic series uses a silica and inorganic salt carrier matrix that provides a protective medium for the active Avobenzone-based photochromic component, improving compatibility with standard ink and coating formulation systems compared to unencapsulated photochromic dyes. The fine 1–10 µm particle size allows smooth integration into screen printing inks, thin-film coatings, and cosmetic bases without requiring additional milling. Multiple colors are available, and grade selection should be based on the target activation color, the formulation system, and the expected UV and temperature conditions in the end-use environment. With 20 years of effect pigment manufacturing experience, Kolortek provides TDS data and application guidance to support grade selection before formulation trials begin — reducing development time and material waste in the qualification process.

Sample sets by color, grade-specific TDS and SDS, and pricing are available upon inquiry. Contact Kolortek's technical team with your target color, formulation system type, and end-use environment conditions for application-specific recommendations.