Laser Processing of PVC Material
Assessing the Human and Environmental Hazards
Lasers use light as an intense heat source to effect a change on materials. The change is generally classified as either a localized heat discoloring, a heat caused material foaming or direct material ablation.
In each of the these three methods the amount of material affected and the exact nature of fumes generated is different depending in large part on the absorption of both the base material and the complexity of additives. In kind, the amount of absorption of a specific wavelength within a given material is affected greatly by the type of laser used (near infrared or far infrared) the assist gases used and the energy density required to process the material. The fumes produced from any one process will vary in its composition, size of particle distribution, and toxicity, all of which are important factors when assessing human and environmental hazards.
PVC materials can be processed using both CO2 lasers operating in the far infrared wavelength (for cutting, marking and engraving) or with YB, YVO4 or YAG solid state lasers operating in the near infrared (for marking).
During the lasering process or whenever PVC is burned, an extremely corrosive, acidic Hydrogen Chloride or HCL is produced. This HCL laden fume must be removed quickly and efficiently for both the safety of the operators and to protect the laser and surrounding equipment.
HCL is classed as a major health hazard, and as a result has a maximum exposure level of 1 ppm (parts per million) over an 8 hour period.
At present no easy or straightforward method exists to accurately estimate the quantity of fume hazards when laser processing. However in the case of PVC some worst case assessments can be made as Benzene, hydrogen chloride (HCl) and methyl methacrylate are typically found to be the dominant emissions. Additionally, there is dramatic circumstantial evidence of long term exposure to PVC fumes damaging the metallic surfaces of laser systems used to process PVC.
Laser safety remains the responsibility of the end user. We can only make recommendation about the use of lasers after it leaves our control. However it should be noted that telltale circumstantial evidence of long term exposure to PVC fumes as evidenced by the damage of metallic components may be cause to void the manufacture’s warranty.