High Density Polyethylene (HDPE) is a Thermoplastic that is characterized by its appearance as a wax-like, lusterless and opaque plastic. Examples are bottles for motor oil, petrol containers, gas tanks for cars, milk bottles, dishware etc. The use of UV-stabilizations (carbon black) improves its weather resistance but turns it black.
This will mark also with the CO2 (low power) and the YB or Nd:YAG. The results will vary dramatically depending on the colorants and stabilizations in the HDPE mix.
Additives to Enhance Laser Marking
“Engelhard Mark-it™ laser marking pigment provides the necessary conversion of laser light energy to thermal energy for YAG laser marking applications. This allows faster marking speeds at low loadings in many polymer systems.
Mark-it™ is antimony-doped tin oxide pigment. It is easily dispersed in polymers as well as liquid colorant systems. The particle size is commonly between 2-3 microns (D(50)). The appearance of the materials incorporating Mark-it™ is affected minimally by this low chroma pigment. Typically, Mark-it™ pigment loading is 0.1% in polyolefins to obtain a high quality mark”.