Hot or Not?
Thermochromic inks make smart packages smarter by communicating temperature.
April 2007 by Chris Mc Loone
|
Although it is difficult to define exactly what smart packaging is, one significant component of any smart package is its ability to communicate with the person interacting with it. In food packaging, some packages can communicate freshness, while others can communicate a product’s history or expiration. In terms of the pharmaceutical market, packages integrating RFID tags to verify authenticity is another example. Other smart packages combine communication with functionality, like self-cooling beer kegs or self-heating soups and coffees.
According to a report from NanoMarkets, LC, titled, “Smart Packaging Markets; 2006-2013,” the global smart packaging market will grow to $4.8 billion in 2011 and reach $14.1 billion in 2013. The report lists various “smart materials” that enhance smart packages. These include shape memory alloys to control the opening and closing of packages depending on environmental conditions, piezoelectric materials to provide power for lighting and audio features on packaging, smart adhesives that can be used in conjunction with smart labels, and thermochromic inks to show when optimal or dangerous temperatures have been reached. NanoMarkets believes that smart materials will have a significant impact on smart packaging technology.
Thermochromic inks, in particular, have found their way into myriad packaging applications.
The heat is on. Or is it off?
Thermochromic inks change color with exposure to heat. They can go from colorful to colorless, colorless to colorful, or change from one color to another, according to Don Duncan, director of research, Wikoff Color Corporation. “Some cause a permanent, irreversible color change, and some give a temporary reversible color change,” he says. “Each themochromic colorant has a fixed temperature range over which its color change takes place.
Deanna Whelan, marketing manager, XSYS Print Solutions, adds, “Reaction temperatures vary depending on the end use. Inks for use in refrigerators are set to activate at low temperatures. Inks for touch are set to activate at typical body temperature. For a microwave oven, they are set at a high temperature.”
Duncan states that there are two types of thermochromic colorants: liquid crystals and leuco dyes. Liquid crystals show color change in a narrow temperature interval, making them suitable for displaying incremental changes in temperature. Their physical form makes incorporating them into packaging inks less common.
Leuco dyes change color over a broader temperature range and are available in a wider range of colors. “A gamut of colorants is available that will make a transition through a broad set of temperature ranges from –25ºC to +65ºC. Leuco dyes are the primary colorants used in packaging inks,” he says.
According to a report from NanoMarkets, LC, titled, “Smart Packaging Markets; 2006-2013,” the global smart packaging market will grow to $4.8 billion in 2011 and reach $14.1 billion in 2013. The report lists various “smart materials” that enhance smart packages. These include shape memory alloys to control the opening and closing of packages depending on environmental conditions, piezoelectric materials to provide power for lighting and audio features on packaging, smart adhesives that can be used in conjunction with smart labels, and thermochromic inks to show when optimal or dangerous temperatures have been reached. NanoMarkets believes that smart materials will have a significant impact on smart packaging technology.
Thermochromic inks, in particular, have found their way into myriad packaging applications.
The heat is on. Or is it off?
Thermochromic inks change color with exposure to heat. They can go from colorful to colorless, colorless to colorful, or change from one color to another, according to Don Duncan, director of research, Wikoff Color Corporation. “Some cause a permanent, irreversible color change, and some give a temporary reversible color change,” he says. “Each themochromic colorant has a fixed temperature range over which its color change takes place.
Deanna Whelan, marketing manager, XSYS Print Solutions, adds, “Reaction temperatures vary depending on the end use. Inks for use in refrigerators are set to activate at low temperatures. Inks for touch are set to activate at typical body temperature. For a microwave oven, they are set at a high temperature.”
Duncan states that there are two types of thermochromic colorants: liquid crystals and leuco dyes. Liquid crystals show color change in a narrow temperature interval, making them suitable for displaying incremental changes in temperature. Their physical form makes incorporating them into packaging inks less common.
Leuco dyes change color over a broader temperature range and are available in a wider range of colors. “A gamut of colorants is available that will make a transition through a broad set of temperature ranges from –25ºC to +65ºC. Leuco dyes are the primary colorants used in packaging inks,” he says.
Companies Mentioned:
 |
|
|
|
Chemistry for the Graphic Arts
What the Printer Should Know About Paper