To provide a laser marking method to a packing film and a marking device to the packing film for printing a date of manufacturing, a manufacturer symbol or the like to the packing film by laser marking without changing the outer surface of a product by the printing of the date of manufacturing, the manufacturer symbol or the like to a packing bag, and furthermore, without using special ink.
In a method of performing laser marking to a packing film obtained by laminating at least a surface layer and a seal layer, when a white ink layer using titanium oxide sandwiched by a film and a film as a colorant is irradiated with a laser beam and the white ink layer is blackened, marking is performed while cooling the surface layer or the seal layer of the packing film.
MORIYA DAISUKE
TAGO KENICHI
