Photochromic Ink

Screen printing Photochromic Ink is a special functional ink. It is used in the screen printing process, enabling printed materials to change color when exposed to ultraviolet rays or sunlight. Once the light source is removed, the original color can be restored, demonstrating a reversible color-changing characteristic.

Working principle:
Under the irradiation of ultraviolet or visible light of specific wavelengths, the structure of photochromic molecules undergoes reversible changes, resulting in color alterations. In screen printing, ink containing photochromic pigments is printed onto the substrate. When the printed matter is exposed to sunlight or ultraviolet rays, the photochromic pigments absorb light energy, and their internal structure changes, presenting different colors. When the light conditions change, such as moving to a shaded area, the structure of the pigment will return to its original state, and the color will also change back to its initial color.

Characteristics:
The color-changing effect is remarkable: The color change is obvious, which can attract people's attention and create a unique visual effect. It is often used to make personalized printed materials, anti-counterfeiting labels, etc.
It has a high number of reversible color changes: Generally, it can undergo multiple color change cycles, has good fatigue resistance, and can meet the frequent color change requirements under different light conditions.
Good stability: Under normal storage and usage conditions, it has stable chemical properties and is not prone to deterioration, ensuring a relatively long period of color change performance.
Wide range of applicable substrates: It can be used for surface printing on various materials, such as paper, plastic, glass, metal, etc., with strong adaptability.

Key points of printing technology:
Screen selection: Usually, a 100-400 mesh screen is chosen. The specific mesh count should be determined based on the surface characteristics of the substrate and the desired printing effect. Coarser screens are suitable for printing on rougher surfaces and can produce thicker ink layers. Finer screens are suitable for smooth surfaces and can achieve more detailed printing effects.
Ink mixing: According to the design requirements and printing process, the photochromic ink is appropriately mixed, such as adjusting the viscosity and fluidity of the ink. An appropriate amount of thinner or thickener can be added to make it reach the viscosity range suitable for screen printing, generally within 30 to 60 seconds.
Printing operation: Pour the prepared ink into the ink tank of the screen printing machine. Use the ink scraper to scrape the ink across the screen plate, allowing the ink to pass through the mesh of the screen plate and be evenly transferred to the surface of the substrate. During the printing process, it is necessary to pay attention to controlling the pressure, speed and Angle of the ink scraper to ensure the ink transfer effect and printing quality.
Drying and curing: After printing, the substrate needs to undergo drying treatment to allow the solvents in the ink to evaporate or undergo chemical reactions to cure. Natural drying or hot air drying can be adopted, etc. The drying temperature and time should be determined based on the specific characteristics of the ink and the material of the substrate. Generally, the natural drying time ranges from several hours to several days, while the hot air drying temperature is around 60-120℃, and the time is several minutes to tens of minutes.

Application field:
Anti-counterfeiting field: Widely applied in anti-counterfeiting printing of currency, securities, certificates, bills, etc. Due to its unique color-changing property and difficulty in replication, it can effectively prevent counterfeiting and forgery, and enhance the reliability of anti-counterfeiting.
Packaging printing: It can be used for high-end gift packaging, cosmetic packaging, food packaging, etc., increasing the appeal and added value of the packaging, enhancing the grade and brand image of the products, and also has a certain anti-counterfeiting function.
Clothing and textiles: Photochromic ink is printed on T-shirts, hats, gloves, scarves and other clothing and textiles to create fashionable garments with color-changing effects. These garments can display unique color changes under sunlight, meeting people's personalized needs.
Advertising and promotional materials: Produce posters, brochures, business cards, souvenirs and other advertising and promotional materials, and use the photochromic effect to attract consumers' attention, enhancing the appeal and promotional effect of the advertisement.
Electronic consumer goods: Applied to the surface printing of electronic products such as mobile phone casings, computer casings, MP3/MP4 players, etc., to enhance the aesthetic appearance and personalization of the products and improve their market competitiveness.
Decorative items: Screen printing is carried out on various decorative items, such as glassware, ceramic products, metal products, etc., to give them a unique color-changing decorative effect, adding interest and artistic sense to the decorative items.