Color change in laser cutting of paper material

Abstract

Laser technology has been developed for cutting of paper materials since the middle of 1970’s. Due to high cost of equipment and maintenance the laser technology has been applied in paper industry only in 1990’s. During its development in the field of processing with different wood-based materials laser technology was confronted with problem of color change in the area of interaction between laser beam and paper material. The main problems in laser cut paper are yellowing and carbonization of the cutting edge. It is commonly known that lignin is the main cause of color change. Due to its optical characteristics lignin is a good absorber of light of various wavelengths compared to other wood compounds like cellulose and hemicelluloses. But structure of lignin is still unresolved nowadays and only few studies concentrate on the phenomena of interaction between laser beam and paper material.The aim of this study was to clarify the nature of color change of the samples which were exposed to influence of light with different wavelength. CO2 laser was employed to carry out cutting of paper material samples. This choice was caused by its high suitability for cutting of wood based materials. CO2 laser operated with wavelength of 10600 nm which is easily absorbed by paper material. The experimental part covers measurement of optical characteristics of the samples after laser cutting as well as during storage time of 21 days. The effect of laser parameters, such as laser power and cutting speed, was considered.Laser technology has been developed for cutting of paper materials since the middle of 1970’s. Due to high cost of equipment and maintenance the laser technology has been applied in paper industry only in 1990’s. During its development in the field of processing with different wood-based materials laser technology was confronted with problem of color change in the area of interaction between laser beam and paper material. The main problems in laser cut paper are yellowing and carbonization of the cutting edge. It is commonly known that lignin is the main cause of color change. Due to its optical characteristics lignin is a good absorber of light of various wavelengths compared to other wood compounds like cellulose and hemicelluloses. But structure of lignin is still unresolved nowadays and only few studies concentrate on the phenomena of interaction between laser beam and paper material.The aim of this study was to clarify the nature of color change of the samples which were exposed to influence of light...