Recycled fibres have become greater and more important source of raw materials in grahpic paper production. The efficiency of this method depends on the technique and printing conditions, kind of ink and kind of printing substrate. Except the mentioned, the type and amount of chemicals used in processing stages, hydrodynamics of process, pH, pulp consistency, time of disintegration, slushing method and other chemical and physical operating conditions influence the efficiency of deinking operation. In the investigations presented in this work, the samples of multicolour digital and conventional offset prints were used. The prints were naturally and accelerated aged before deinking flotation. Some characteristics of the optical values before and after flotation were observed on handsheets. The investigation results show that natural ageing of prints influences the handsheet brightness, deinkability respectively. This influence is greater with conventional offset prints with the ink with greater ration of renewable raw materials. With handsheet after disintegration of the accelerated aged prints of digital offset printing, the decrease of the particle size and smaller increase of handsheet brightness can be noticed by the increase of ageing time. The investigation results show greater change of relative reflection of handsheet before and after deinking flotation in the function of accelerated ageing.
展开▼
