Thermochromic Leuco Dyes (LD's)
Leuco Dyes change color with changes in temperature. LD's are reversible, meaning they change color back and forth as the temperature fluctuates. It takes about a 5ºF (3ºC) temperature change for the LD to change color.
Activation temperature points range from low refrigeration type temperatures through normal body temperatures to high temperatures that exceed the pain threshold.
• Cold Activated Thermochromic Ink is used on labels and packaging to create a color change when cooled. (Clear to Color at 15ºC / 59ºF)
• Touch Activated Thermochromic Ink will vanish when rubbed or touched to reveal an image or another color printed beneath. (Color to Clear at 31ºC / 88ºF)
• High Temperature Thermochromic Ink is designed to change color just below the pain threshold alerting consumers and users to a safety hazard - Too Hot! (Color to Clear at 47ºC / 117ºF)
Leuco Dye products are available in a wide variety of colors, temperatures and forms, which include powder, slurry, water and solvent based ink, epoxy, and master batch.
LD's are more robust and less expensive than liquid crystals and can be used in a wider range of inks, plastics, etc. Because LD's are not very sensitive they do not make accurate thermometers, but are used in applications where larger temperature differences are present or when temperature accuracy is less important. A LD's life span is adversely affected by sunlight, extreme temperatures, and contact with aggressive solvents.
Applications are only limited by the imagination and include advertising and promotional applications, product labeling, toys, game pieces, and packaging. LD’s give life to materials and printing, offering the opportunity to engage and excite your audience with a graphic or component that changes color when stimulated by temperature.