Product Description
Photochromic Pigments are photochromic microcap-sules in a powder pigment form. They are specifically designed for use in non aqueous based ink systems although their use is not limited to this. They can be used to formulate non aqueous based Flex graphic, UV, Screen, Offset, Epoxy, and Gravure ink formulations (for aqueous applications we would recommend using a photochromic slurry). Photochromic powders are color-less in their inactivated state and become colored when exposed to an ultraviolet light source. They will respond to natural sun light as well as artificial sources of 365nm "black light".
Technical Specifications
Solids: 98% +/- 2%
Particle Size: <7 microns (97%)
Shelf Life: 12 months
Storage and Handling
Photochromic Pigments are more sensitive to the influences of solvents, pH, and shear than many other types of pigment. It should be noted that there are differences in performance of the various colors so that each should be thoroughly tested before commercial application.
Photochromic pigments have excellent stability when stored away from heat and light. Store below 25oC. Do not allow it to freeze, as this will damage the photochromic capsules.
Long-term exposure to UV light will degrade the photochromic capsules ability to change color. A shelf life of 12 months is guaranteed provided that the material is stored in a cool and dark environment. Storage longer than 12 months is not recommended. Consult product MSDS prior to use.
Sensitivity
Photochromic microcapsules are sensitive to adverse environ-mental conditions. These are listed below, along with a description of the nature of the sensitivity, and recommendations with regards to them.
Mixing
Photochromic pigments can withstand most standard mixing procedures. Some shear is necessary as the microcapsules agglomerate slightly when in powder form. To disperse the powder we recommend the use of a three-roll mill. If too much shear energy is used (e.g. bead mills) then the microcapsules can be crushed and the photochromic function destroyed.
Light
Photochromic pigments will degrade from UV exposure over Time. Exact life expectancies depend on the intensity and duration of the UV exposure. Some colors will degrade faster then others. Do not use UV inhibitors over the photochromic powders as it will interfere with the color change properties.
Heat
Some colors may degrade quicker over time when held at elevated temperatures.
Chemicals
Photochromic pigments can be incorporated into many types of no aqueous inks. However, photochromic materials are sensitive to chemical exposure. Care must be taken to avoid the use of polar solvents such as alcohols, acetates, etc. as these can damage the microcapsule walls.
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