Thermochromic Ink

Thermochromic Ink is a special ink that can change color with temperature variations. Screen printing Thermochromic Ink is to use the screen printing process to print this thermosensitive ink onto the substrate, achieving the color change effect of the product at different temperatures.

Working principle:
Thermochromic ink is mainly composed of color-changing substances, carriers and other additives, etc. Common color-changing substances include liquid crystals and leUCO dyes, etc. Among them, the uco dye color-changing system is usually composed of electron donor components, electron acceptor components, solvents and resins, etc. At different temperatures, the reaction equilibrium between electron donors and acceptors will change, resulting in color changes. When the temperature reaches the color-changing temperature of the ink, the microcapsules in the ink undergo chemical reactions or physical changes, causing the color to change. When the temperature drops, it will return to its original color.

Classification:
Reversible thermochromic ink: When the temperature rises or drops to a certain extent, the color of the ink will undergo reversible changes, that is, it will change color when heated and recover when cooled, or it will change color when cooled and recover when heated. For instance, the common 31℃ black reversible thermosensitive ink is black at room temperature. When the temperature reaches above 31℃, it turns colorless and returns to black when the temperature drops.
Irreversible thermochromic ink: It changes color when exposed to heat and does not return to colorless when cooled. For instance, the 90℃ irreversible heat-sensitive red ink will change from colorless to red after being heated, and the color is irreversible.

Characteristics:
Obvious color changes: It can display distinct color differences at different temperatures, has a strong visual effect, and is easy to observe and identify.
Both reversibility and irreversibility: According to different demands and application scenarios, reversible or irreversible thermochromic inks can be selected, providing more flexibility for product design and use.
Good stability: Under normal storage and usage conditions, it can maintain color change performance for a relatively long time and is not prone to failure due to factors such as time and light.
Wide application range: It can be used on various substrates such as paper, plastic, glass, metal, etc., and can meet the diverse needs of different industries and products.

Key points of printing technology:
Ink preparation: Before printing, it is necessary to select the appropriate thermochromic ink based on the specific printing requirements and the characteristics of the substrate, and ensure the quality and performance of the ink are good. For two-component thermochromic inks, they should be mixed and stirred in accordance with the prescribed proportion to ensure thorough uniformity.
Screen selection: Based on the material, surface condition and printing accuracy requirements of the substrate, select the appropriate mesh count and screen size of the screen. Generally speaking, for more delicate printing effects, a screen with a higher mesh count can be chosen, such as around 200 mesh.
Printing parameter control: During the printing process, parameters such as printing pressure, squeegee hardness and printing speed must be strictly controlled. The printing pressure should be moderate, which can ensure the full transfer of ink without damaging the substrate and the screen. The hardness of the scraper is usually selected between 60 and 70 Shore hardness to ensure the uniform application of the ink. The printing speed should be adjusted according to the equipment and actual situation to ensure the printing quality and efficiency.
Drying and curing: The thermochromic ink after printing needs to be dried and cured to form a firm ink layer and bond closely with the substrate. The drying method can be selected based on the type of ink and the characteristics of the substrate, such as natural drying, hot air drying or ultraviolet curing, etc.

Application field:
Printing industry: It is used for printing temperature indication labels, anti-counterfeiting marks, promotional posters, artworks, etc. For instance, thermochromic ink can be printed on product packaging to display the temperature status of the product through color changes, reminding consumers to pay attention to the storage temperature. Or use color changes on promotional posters to attract attention and increase the interest and appeal of the advertisement.
Textile industry: It can be applied to the printing and dyeing of textiles such as clothing and accessories, creating fashionable products with color-changing functions. For instance, color-changing T-shirts, when the temperature changes, the patterns or colors on the clothes will change accordingly, adding fun and personalization to wearing.
Plastic products industry: It is used to produce various plastic products with temperature indication functions, such as children's toys, daily necessities packaging, etc. For instance, when the temperature of children's toys is too high, the thermochromic ink on the surface will change color, reminding parents to pay attention to the temperature of the toys to prevent scalding children.
Glass products industry: It can be printed on the surface of glassware, window glass, etc., to achieve multiple functions such as temperature indication and decoration. For instance, thermochromic ink is printed on glass tea sets. When hot water is poured into the tea sets, the color of the ink changes, indicating the temperature state of the tea sets and also enhancing their artistic appeal.
The electronic and electrical industry: It can be used for printing on the shells of electronic devices, marking circuit boards, etc., and for temperature monitoring, anti-counterfeiting and other aspects. For instance, thermochromic ink can be printed on the surface of the heat sink of electronic devices to visually display the temperature of the heat sink through color changes, so as to promptly detect the heat dissipation problems of the equipment.