Smart label ink

The invention of the printing technique marked a major leap in the spread of human culture. Ink, a special colorant used for printing, gradually evolved into an independent industry. Initially, ink was only black, but over time, it developed into a complex system that includes various colors, binders, thinners, and additives. With the continuous innovation in printing equipment and the introduction of new types of inks with different properties, the packaging and printing industry has entered a fast development phase. As a key part of packaging, labels have become an essential element in daily life, and their applications are expanding rapidly, drawing global attention.

Today, label printing techniques include embossing, flexography, offset, gravure, and screen printing. For high-end label production, companies often combine multiple methods—such as embossing, screen printing, and flexo—to create a multi-layered, hard-to-copy design. However, despite the variety of printing methods, most follow established rules with limited variation. The diversity of inks used in label printing plays a crucial role, as it contributes to the unique "identity" of each label.

Labels are no longer just simple product indicators; they now convey more meaning and visual appeal. From traditional visual impact to intelligent information display, inks have been central to this evolution. Anti-counterfeiting inks help secure labels, magnetic inks allow for hidden data storage, and smart labels like RFID and temperature-sensitive tags have emerged in recent years.

(1) Temperature-Change Ink

Temperature-change labels use thermochromic ink, also known as heat-sensitive or temperature-indicating ink. These inks change color based on environmental temperature, offering visible or invisible signs that help verify product authenticity and prevent counterfeiting.

Normally, temperature-changing inks share similar components with regular inks, such as binders, additives, and fillers, but the pigment is sensitive to temperature. There are five main types: reversible color inks, color-developing inks, color-removing inks, memory inks, and interval color-developing inks. Each has distinct characteristics.

1. Reversible Color Ink

This type of ink changes color when heated and returns to its original color when cooled. Common color changes include yellow to red, green to yellow, red to green, and others. The temperature sensitivity is typically around 60°C. The effect depends on the fineness of the ink particles, so screen or gravure printing is recommended.

2. Reversible Color-Developing Ink

These inks are initially colorless but develop color when heated and fade when cooled. They can show colors like rose red, peacock green, emerald green, blue, and brown black. The temperature sensitivity is around 60°C, and screen or gravure printing is ideal for best results.

3. Reversible Achromatic Ink

When heated, this ink loses its color and regains it when cooled. It can be printed using four methods, but screen and gravure provide the best effects. Its sensitivity ranges from 7–15°C, 25–32°C, 37–42°C, 45–50°C, and 60–65°C. Colors include medium yellow, gold red, royal blue, sky blue, emerald green, and more.

As technology continues to evolve, the role of inks in labeling will only grow, enabling more advanced features and greater security in product identification.