Photochromic Pigment Uses - Photochromic Pigment Examples in 2024

17 Years of Experience in Photochromic Powder Uses - Original Photochromic Pigment Manufacturer - KingChroma

What is photochromic pigment used for?

1. Photochromic pigment for Plastic products: The recommended ratio of photochromic pigments is 0.8-3%. They are suitable for injection and extrusion of plastic materials, including PE, PP, ABS, PS, PVC, PU, TPU, TPR, EVA, photosensitive PE masterbatch, photosensitive PMMA masterbatch, etc.

2. Photochromic pigment for Photochromic inks: water-based and oil-based inks. There are dedicated inks for fabrics, paper, synthetic films, glass, ceramics, metals, plastic and wooden products. They have good adhesion and color-changing effects. Photochromic coatings and paints apply to all surfaces. Other products of KingChroma: I. Thermochromic raw materials: color changes are controlled by differences in temperature. Currently, the available products include low-temperature thermochromic products, hand-felt thermochromic products, high-temperature thermochromic products, thermochromic powder for plastic injection and extrusion, and dedicated inks for other materials.

3. Photochromic pigment for Paints: The recommended ratio of photochromic powder is 10-30%. Photochromic powder is suitable for surface paints, including PMMA spray paint, ABS spray paint, PVC spray paint and water-based spray paint.
Inks: The recommended ratio of photochromic pigments is 20-40%. Photochromic pigments are suitable for printing of fabrics, paper, synthetic films, glass, etc.

Pigment Powders

Chameleon Powder

Glow in the dark powder

Photochromic Pigments

Pearl Powder

Photochromic Pigment Use FAQs

Photochromic powder is an instable compound (difficult to change), so it is far less resistant to light, heat and ageing than ordinary pigments. Attention must be paid during the use of photochromic powder.

  1. Light resistance

Photochromic pigments have low light resistance. They fade and fail quickly in case of exposure to strong sunlight. They must be prevented from long-term exposure to strong sunlight and ultraviolet light, in order to extend the service life.

  1. Heat resistance

Photochromic pigments are resistant to 230℃ in a short time (about 10 minutes). They can be applied in injection molding and high-temperature curing. However, the thermal stability of photochromic pigments varies in the chromatic and achromatic status. Photochromic pigments have higher stability in the chromatic status than the achromatic status. At a temperature of more than 80℃, organic matters in photochromic pigments will degrade. Therefore, photochromic pigments should not be used at a temperature above 75℃ for a long time.

1.1 Injection molding and extrusion:

Features: thick capsule wall, high strength, good heat resistance, even dispersion, fewer residual colors.

1.2 Scope of application

It can be used in injection molding and extrusion of transparent or translucent plastics, such as polyethylene (PE), polypropylene (PP), polyene (PS), soft polyvinyl chloride (S-PVC), AS and ABS. It can also be mixed with unsaturated polyester, epoxy resin, plexiglass or nylon monomer in casting, mold pressing and curing.

1.3 Dosage:

During injection molding, extrusion, casting, mold pressing and curing, photochromic pigments account for 0.4-3.0% of plastics, usually 0.6-2.0%. Photochromic pigments should be fully mixed with plastic particles (use a small amount of white oil during mixing). Ordinary pigments (or dyes) should account for about 0.5-2.5% of photochromic pigments if they are mixed.

1.4 Colorants:

During mass production, photochromic pigments are mixed with polyethylene wax or polystyrene wax to make the color masterbatch, in which pigments account for 10%. Then they are mixed with plastic particles. In this way, photochromic pigments are dispersed more evenly.

1.5 Temperature:

The processing temperature should be below 200℃ and never greater than 230℃. In addition, the time of material heating should be minimized. (High temperature and long-time heating will affect the color-changing properties of these pigments.)

1. Binder (resin) selection:
Resin has very important impact on the color concentration and surface luster of photochromic ink. The content of pigments in photochromic ink is far greater than that in ordinary ink. If photochromic ink is made with resin from ordinary ink, it cannot be used due to too high viscosity. Thus, it is necessary to reduce resin and increase solvents, in order to reduce the ink viscosity.

2. Solvent selection and its impact on color-changing properties
2-1 Impact of the optical refractive index of solvent on the color concentration of photochromic ink (coating)
The optical refractive index of microcapsule in photochromic pigments is about 1.50-1.54. If the optical refractive index of the solvent is the same as or close to ink, the ink will have high concentration, such as toluene, xylene and benzyl alcohol (optical refractive index: 1.496, 1.493 and 1.540, respectively). On the contrary, if the solvent and ink are greatly different in the optical refractive index, the ink will have a low apparent color concentration. Solvents only have temporary impact on the color concentration of photochromic ink. After printing is completed, such impact of solvents on ink will gradually disappear.

2-2 Impact of solvent on color-changing properties of pigment
The resistance of photochromic pigments to solvents varies. After soaking in some solvents for 6 months, the color-changing properties of photochromic pigments are not affected. But other solvents may erode and penetrate into microcapsule surfaces within a few hours to weeks. In this case, the color-changing properties of photochromic pigments will degrade and even completely disappear. After the solvent volatilization, some color-changing properties may be partially recovered, but some properties are completely unrecoverable. In general, the solvents containing 3 carbon atoms or less may cause more erosion damage to photochromic pigments, and the solvents containing 6 carbon atoms have little impact. In addition, solvents have more obvious erosion effects at high temperatures.

Notes: Finished diluents/mixtures commonly used in oil processing and some resin solutions may contain ethanol, acetone, propanol and other components harmful to the properties of photochromic pigments. Even in case of fewer harmful components, they have serious impact.

  1. Preferably, substrates with a pH value of 7-9 should be used.
  2. The optical fatigue of photochromic pigments is caused by excessive exposure to UV light and too high concentration. It is recommended to add light absorbers and antioxidants to reduce the optical fatigue.
  3. Additives (antioxidants, heat stabilizers, UV light absorbers and inhibitors) in photochromic powder can reduce the optical fatigue. But the proportion of additives depends on the medium used. An incorrect proportion will accelerate the optical fatigue.
  4. Photochromic pigments do not contact any substances harmful to the human body. They comply with the safety specifications of toys and food packages.

How can photochromic powder not fade on fabric?

It is often reported that fabric applied with photochromic powder will fade after washing, thus affecting the product quality. So, how to make the powder stay put? Here is a good way to do this for everyone.

What are the price differences in photosensitive pigment powders?

Photosensitive pigment powder is sold at variable prices in the market, but with similar powder. Why are some particularly expensive and others relatively low? There is also a significant difference in quality, some are good and some are bad. What are the differences specifically?

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