A Theory of Interaction Mechanism between Laser Beam and Paper Material

Paper making and converting industry in Europe is suffering from transfer of basic manufacturing to fast-growing economies, such as China and Brazil. Pulp and paper production volume in Finland, Sweden and France was the same in 2011 as it was in 2000. Meanwhile China has tripled its volume and Brazil doubled. This is a situation where innovative solutions for papermaking and converting industry are needed. Laser can be solution for this, as it is fast, flexible, accurate and reliable.Before industrial application, characteristics of laser beam and paper material interaction has to be understood. When this fundamental knowledge is known, new innovations can be created. Fulfilling the lack of information on interaction phenomena can assist in the way of lasers for wider use of technology in paper making and converting industry.This study was executed by treating dried kraft pulp (grammage 67 g m-2) with different laser power levels, focal point settings and interaction time. Laser equipment was TRUMPF TLF HQ2700 CO2 laser (wavelength 10.6 μm). Interaction between laser beam and dried kraft pulp was detected with multi-monitoring system (MMS), which consisted of spectrometer, pyrometer and active illumination imaging system.There is two different dominating mechanisms in interaction between laser beam and paper material. Furthermore, it was noticed that there is different interaction phases within these two interaction mechanisms. These interaction phases appear as function of time and as function of peak intensity of laser beam. Limit peak intensity divides interaction mechanism from one-phase interaction into dual-phase interaction.