Thermochromic Pigments Heat Activated Color Changing

Technical Description

The thermochromic effect in the KTP series is produced by microencapsulated leuco dye systems. Each pigment particle is a microcapsule containing three components: a leuco dye (the color-forming agent), a color developer (which protonates the dye to produce color at lower temperatures), and a solvent (which controls the activation temperature by melting at a defined point and dissolving the developer-dye complex). When the temperature rises above the activation threshold, the solvent melts, the developer dissociates from the dye, and the dye returns to its colorless leuco form — the color disappears. When the temperature drops, the system reverses and color returns.

The composition of KTP-16-BR illustrates this structure: Polyoxymethylene Melamine forms the microcapsule shell, Cholesterol functions as the solvent/activation medium, and Red 28 is the leuco dye colorant. The capsule wall protects the internal chemistry from direct contact with the formulation medium, which is why these pigments can be dispersed in water-based, solvent-based, and UV-cure systems without the internal chemistry being disrupted — provided solvent exposure and processing temperatures remain within the recommended limits.

The colored-to-another-color variant works by layering or blending thermochromic pigments with conventional pigments: below activation temperature, both contribute to the visible color; above it, the thermochromic component becomes colorless and only the base pigment color remains, producing a color shift rather than a disappearance. The food-grade BPA-free series uses developer chemistry that excludes bisphenol A, relevant for applications in direct or indirect food contact contexts.

Activation temperature is a key specification that varies across the product range. Common activation points are available from approximately 15°C through to 65°C and above. The specific activation temperature for any grade should be confirmed from the product TDS before formulation.

Key Features & Benefits

Product Pictures

Applications

Activation temperature selection is critical for each application. Contact us with your target activation temperature and formulation system for grade-specific guidance.

Product Specifications

Example product shown. Full series data available upon request.

Full TDS and SDS available upon request. Additional particle size grades available.

Industry Solutions

Thermochromic pigments are functional materials — the activation temperature, color change behavior, and chemical compatibility with the formulation system all have to be correct simultaneously for the application to work. Buyers sourcing from unfamiliar suppliers face two common problems: receiving pigments where the actual activation temperature differs from the stated specification, and getting inadequate technical support to troubleshoot compatibility issues when the pigment interacts unexpectedly with a specific resin, solvent, or processing temperature. For applications like food packaging or children's products, there is also the additional dimension of regulatory compliance — specifically the presence or absence of BPA in the developer chemistry.

Kolortek Thermochromic series addresses these issues through three distinct sub-series — colored-to-colorless, colored-to-another-color, and BPA-free food grade — so buyers can select the appropriate chemistry for their application without reformulating around a one-size-fits-all product. The microencapsulated structure isolates the thermochromic chemistry from the surrounding formulation, which broadens compatibility across water-based, solvent-based, and UV systems within the recommended processing parameters. With 20 years of effect pigment manufacturing experience, Kolortek maintains consistent activation temperature and color strength across production batches — the two variables that matter most for functional thermochromic applications. Technical data sheets, safety data sheets, and application guidance are available for all grades.

Sample sets by color and activation temperature, grade-specific TDS, and pricing are available upon inquiry. Contact Kolortek's technical team with your target activation temperature, formulation system, and application requirements.