Thermochromic tapes are adhesive tapes that change color with the change of temperature. These tapes use temperature-sensitive colors coating that shifts from one color to another depending on temperature. This makes this tape useful in different areas: from storage, transportation and packaging of temperature sensitive consumer goods to automotive and aerospace engineering, environmental monitoring, quality control and so on. Thermochromic tapes make it extremely easy to monitor the temperature of the surface it is adhered to. In a simple glance, one can know what is the package temperature.
How do Thermochromic Tapes Work?
Thermochromic tapes are just like any other plastic tape, except that they are printed using inks that exhibit thermochromism. Thermochromism is the property of a substance to change their color upon exposure to different temperature. Special papers and polymers exhibit thermochromism. Normally, thermal printers use thermochromic papers. Here, the color change is permanent. Certain polymers show thermochromism by changing their molecular structure upon the application of heat.
The inks in thermochromic tapes use liquid crystals or leuco dyes. In both these types of inks, the molecules of the inks undergo certain physical changes with temperature. These changes are reversible, and so, when the temperature returns to normal, the molecules return to their default configuration. This change in the state of the molecules causes shifting colors.
Types of Thermochromic Inks
Certain liquid crystals and leuco dyes exhibit thermochromism. Thermochromic paints, tapes, and labels generally make use of these two compounds.
Liquid Crystal Inks
Liquid crystal inks, because of their crystalline properties change their color at very specific temperatures. These are useful in areas where the precision is much more important. Furthermore, some liquid crystals can exhibit different colors at different temperatures. Upon heating liquid crystals, the molecules change their orientation. Depending on their orientation, they reflect or absorb certain wavelengths of light, which gives them different colors at different temperatures. Generally, at high temperatures, they have a blue or violet color, whereas in low temperatures they have a red or orange color. Liquid crystals are generally microencapsulated in the inks, in a form of suspension. These inks act as level indicators in propane tanks, in thermometers, aquariums, refrigerators, medical packaging and so on.
Leuco dyes are useful in the areas where temperature accuracy is not mandatory. They illustrate if something is too hot, too cold or if the temperature is alright. They are mostly used in novelty items, kettles, bath toys and so on. Leuco dyes contain a combination of pigments. Among one of these pigments is the one that can turn colorless at a certain temperature. So, when one pigment turns colorless, the combination of the pigments seem to shift their color.
Thermochromic Tapes in Packaging
In packaging, thermochromic tapes can present a premium convince feature. For instance, certain pharmaceutical drugs need storage at certain temperatures. These are also useful in food packaging to monitor proper storage temperatures. In beverage packagings such as beer cans or coffee cups, thermochromic tapes can indicate if they are cold or hot enough. Ready-to-cook food packaging can also use thermochromic tapes to check if the food is warm enough while microwaving. Here are some examples of thermochromic tapes in product packaging.
Counterfeit prevention: Thermochromic tapes also act as an alternative to a hologram and other security seals. They can also incorporate branding details. Tapes with thermochromic inks that permanently change color are useful for making tamper-evident packaging.
Novel packaging: Coca-cola Turkey introduced a packaging for its canned beverage that changes color when the beverage is chilled and is ready for consumption. One can achieve the same effect using thermochromic tapes and labeling on packaging. It can also help to check if a food product is warm enough or not.
Consumer Interactive Marketing: Thermochromic tapes and labeling are great for making interactive packaging that will encourage consumers to take the product off the shelf and explore it. Products that unexpectedly change colors when held in hand will surely grab more attention.
You might also like to read about different packaging printing methods.