A method for printing a ribbon, comprising the steps of: - feeding a ribbon along a feeding path, - impregnating said ribbon with a predetermined amount of acidic or alkaline solution thereby obtaining an impregnated ribbon, - feeding a first tape consisting of a plastic material and a second tape consisting of a plastic material along respective feeding paths (Y, Z), wherein at least one dye layer (6, 6') comprising pigments of acidic and/or reactive pigments, or pigments of basic colors, is applied to at least one of said first and second tapes (4, 5) consisting of a plastic material, - coupling said impregnated ribbon to said first and second tapes (4, 5) consisting of a plastic material so that said impregnated ribbon is interposed between said tapes (4, 5) consisting of a plastic material, forming a multi-layer belt and so that said at least one dye layer (6, 6') is arranged in contact with said impregnated ribbon, - making two continuous weld seams parallel to the feeding path at respective side edges of the multi-layer belt so as to constrain said impregnated ribbon to said first and second tapes (4, 5) consisting of a plastic material, - advancing said multi-layer belt along a vaporization path where the multi-layer belt is heated on both sides, defined by said tapes (4, 5) consisting of a plastic material, so as to vaporize at least partially the predetermined amount of acidic or alkaline solution for activating the reaction of the dyes with the impregnated acidic or alkaline solution and obtaining a migration of the dyes from the dye layer (6, 6') towards the ribbon forming a printed ribbon, - making two continuous cutting lines, parallel to the two continuous weld seams, interposed between or at said continuous weld seams, so as to trim the side edges of the multi-layer belt, - decoupling the multi-layer belt by separating the first and second tapes (4, 5) consisting of a plastic material from the printed ribbon. - feeding a ribbon along a feeding path, - impregnating said ribbon with a predetermined amount of acidic or alkaline solution thereby obtaining an impregnated ribbon, - feeding a first tape consisting of a plastic material and a second tape consisting of a plastic material along respective feeding paths (Y, Z), wherein at least one dye layer (6, 6') comprising pigments of acidic and/or reactive pigments, or pigments of basic colors, is applied to at least one of said first and second tapes (4, 5) consisting of a plastic material, - coupling said impregnated ribbon to said first and second tapes (4, 5) consisting of a plastic material so that said impregnated ribbon is interposed between said tapes (4, 5) consisting of a plastic material, forming a multi-layer belt and so that said at least one dye layer (6, 6') is arranged in contact with said impregnated ribbon, - making two continuous weld seams parallel to the feeding path at respective side edges of the multi-layer belt so as to constrain said impregnated ribbon to said first and second tapes (4, 5) consisting of a plastic material, - advancing said multi-layer belt along a vaporization path where the multi-layer belt is heated on both sides, defined by said tapes (4, 5) consisting of a plastic material, so as to vaporize at least partially the predetermined amount of acidic or alkaline solution for activating the reaction of the dyes with the impregnated acidic or alkaline solution and obtaining a migration of the dyes from the dye layer (6, 6') towards the ribbon forming a printed ribbon, - making two continuous cutting lines, parallel to the two continuous weld seams, interposed between or at said continuous weld seams, so as to trim the side edges of the multi-layer belt, - decoupling the multi-layer belt by separating the first and second tapes (4, 5) consisting of a plastic material from the printed ribbon.