Sunlight-changing OP powder is a special type of small-molecule material that can alter its color under ultraviolet light. It appears as a white or nearly white powder. The color-changing mechanism stems from the excitation of OP molecules by UV radiation, which modifies their molecular structure and induces color shifts. When UV exposure is removed, the OP molecules revert to their original structure, restoring the initial color.
- Basic colors
OP powder is available in a variety of colors, such as purple, blue, yellow, green, red, and more. Different colors of OP powder can be mixed to create a wider range of color variations. Currently, over 100 colors are available for selection. Additionally, customized products can be provided based on the specific applications of customers in niche scenarios. - Color-changing conditions
OP powder itself does not change color when exposed to ultraviolet light and requires dissolution in a medium (such as organic solvents, resins, or plastics) to become photosensitive and change color. When dissolved in media with different polarities, the color change varies. The resulting product appears colorless (or its original color) in dark or indoor lighting conditions but quickly displays its color under UV or sunlight exposure. When UV light is blocked, it reverts to colorless (or its original color). - Excitation wavelength
It strongly absorbs ultraviolet light in the range of 280nm to 400nm, which can excite the OP powder to change color. - Solubility
OP powder can dissolve in most organic solvents, such as ethyl acetate, butyl acetate, tetrahydrofuran, acetone, benzyl alcohol, toluene, and styrene. Photoreactive dyes exhibit lower solubility in highly polar solvents and higher solubility in less polar or nonpolar solvents. In certain solvents, such as acetonitrile, photoreactive properties are not observed. - pH Applicability
OP powder exhibits stable color-changing properties in neutral environments, while its performance is slightly inferior in alkaline or acidic conditions. - Weather resistance
Prolonged exposure to high-intensity ultraviolet radiation can reduce the number of color changes in OP powder and degrade its coloring effect, thereby shortening the service life of photochromic raw powder. The weather resistance of different OP powders varies, and the same OP powder may exhibit different weather resistance in different media. To enhance weather resistance, specific amounts of protective agents, such as antioxidants and UV stabilizers, can be added based on the specific conditions.