The color of plastics is usually obtained in two ways: toner or dye. Toner is usually organic or inorganic structure, they do not dissolve in plastic. Organic toner has better coloring power than inorganic toner, but its opacity is worse. Dyes are organic molecules and dissolve in plastic. No particles can be seen when the dye is added. The transparency of the material remains the same.
In plastic laser welding, the upper material requires laser penetration and the lower material requires laser absorption. For the underlying material, if the color of the plastic is not good for the wavelength of the laser absorption performance, can be added absorbent.
For the upper material, the addition of color will affect the laser penetration. In the plastic that has color commonly, because apply requirement opaque, the toner that plastic joins is inorganic toner. As can be seen from the above table, the particles of the inorganic pigment are relatively large. Like the crystal particles of semi-crystalline materials, these particles will produce refraction and reflection on the laser penetration, affecting the penetration rate of the laser and thus affecting the welding performance.
For laser welding of colored plastics, the ideal solution is to add organic dye or toner to the plastic. These organic molecules are very small and can be completely dissolved in the plastic without affecting the laser penetration performance of the plastic itself. However, the organic molecules of the toner or dye opacity is too poor, generally in the color match or match with inorganic toner or additives.
Laser welding of color plastics requires special color matching of upper plastics, which only a few professional suppliers Know How at present, and the price of color matching master or material is much more expensive than that of ordinary materials. Therefore, it is necessary to avoid using colored plastics for laser welding in practical applications.