The 20Th INTERNATIONAL DAAAM SYMPOSIUM

The 20th INTERNATIONAL DAAAM SYMPOSIUM "Intelligent Manufacturing & Automation: Theory, Practice & Education" 25-28th November 2009, Vienna, Austria

RECYCLING OF WASTE PAPER WITH DIFFERENT DENSITY OF LIQUID TONER

BOLANCA MIRKOVIC, I[vana]; MAJNARIC, I[gor]; BOLANCA, Z[denka] & GRGASOVIC, A[nte]

Abstract: The investigation results of the liquid toner density of conditions in different phases of indirect electrophotographic ElectroInk in indirect electrophotographic printing on the print printing (scorotrone voltage, laser strength, offset cylinder recycling effectiveness are presented in this work. The voltage, concentration of the liquid toner etc.). The deinking process mechanism in relation to the substrate investigation results can be applied in the production of the characteristics used in printing is discussed. In the scientific recycled papers, in formulation of new printing materials and in sense the work is a contribution to the explanation of the print the design of graphic products taking into consideration the deinking mechanism in relation to the concentration of the postulates of the sustainable development. liquid toner in combination with the coated and uncoated printing substrate. Almost linear relationship of the ElectroInk 2. EXPERIMENTAL concentration, the number of particles and the area size they ¶ occupy on handsheet after recycling, when the print was made The prints made on digital offset machine Turbo Stream HP on the uncoated paper has been determined. Such relationship Indigo were used for analysis. The printing form contained was not determined when the print was made on the coated different printing elements: standard CMYK step wedge in the substrate. range from 10-100% tone value, standard ISO illustration for Key words: electrophotographic printing, liquid toner, the visual control, textual positive and negative microelements, recycling, image analysis, brightness wedges for determination the greyness and the standard wedge ¶ with 378 patches for production of ICC profiles and 3D gamut. 1. INTRODUCTION Five different densities of liquid ElectroInk (D 1.20 - 2.00) ¶ were used in combination with the printing substrate as follows. The effectiveness of the deinking process in paper The fine art paper (Symbol Gloss) and the wood free natural recycling depends on numerous factors. The following ones paper (Acroprint), all the products of the firm Fedrigoni, were have to be mentioned: the printing technique, the ink used as the printing substrates. Papers do not differ in their characteristics, the properties of the printing substrate and the basic chemical composition of the paper raw materials. The components of the coating. The other influential factors are the only difference is in the finishing process referring to coating. kind and quantity of chemicals used in different phases of the For print recycling the method of alkaline chemical process as well as the chemical and physical conditions of the deinking flotation was used, which was described in details in system such as pH value, consistency of fiber suspension, the previous work (Bolanca & Bolanca, 2005). The handsheets defibering time and the hydrodynamic factors of the flotation were made using a laboratory sheet former, according to process (Lassus, 2000). standard method T 205. The size, shape and the surface properties of the dispersed For determining ISO brightness of the recycled fibres the ink particles, the air volume and the size of the air bubbles have spectrophotometer DataColor, Elrepho 450X was used. special importance for the effectiveness of deinking flotation. Residual toner size, toner dirt particles number and toner area The effectiveness of the process depends on the ability of the were assessed with image analysis software Spec*Scan, printing ink adherence on air bubbles and the strength of this Apogee System. This system is utilizing scanner to digitize bond in order to prevent their detaching and rebinding to the image. Threshold value (100), white level (75) and black level cellulose fibers (Renner, 2009; Carre, 2008). (65) were chosen after comparing computer images to In the described problems, the majority of authors handsheet. researched the hydrodynamic factors of the process and the influence of chemical and physical conditions of the system on 3. RESULTS AND DISCUSSION the process effectiveness, while the influence of the printing techniques and the conditions in printing process haven’t been For observing and explaining the deinking flotation studied much (Li et al., 2007, Zhao et al., 2004). process, the image analysis method and the brightness of The investigation results of the liquid toner density of handsheet have been chosen. In figure 1 the count of dirt ElectroInk on the effectiveness of the print recycling have been particles (toner particles) on handsheet made from the fibres presented. Deinking process mechanism in relation to the obtained from print recycling with different liquid toner characteristics of the printing substrates used in printing is concentrations is presented. discussed. In scientific sense, the work is the contribution to the The investigation results show the trend of dirt particles explanation of the print deinking mechanism in relation to the increase on handsheet after flotation in the function of the liquid toner concentration in combination with the coated and concentration increase of the ink carrier in ElectroInk when the uncoated printing substrates. uncoated paper was used for printing (628-1024). However, The recent investigations have proved the bad when the paper coated on both sides was used for printing the effectiveness of print recycling made in the technique of digital offset printing. The investigations have to prove if it is possible to contribute to solve the mentioned problem by choosing the Fig.1 Count of dirt particles on the handsheet made after from the fibres of the prints printed on coated paper (34,6-68,4 flotation % for D from 1.20-2,00). One of the conditions for the removal of the toner particles Fig. 2 Area of the dirt particles on the handsheet after flotation in the flotation process is the fragmentation of toner particles as well as their size. The number of particles on handsheet before number of dirt particles of ElectroInk on handsheet varied and flotation decreases at 77,3- 90,0% in relation to the density of there is no expressed trend in relation to the toner concentration toner used for print preparation when the uncoated paper was used in the printing phase (673-892). The difference in the total used for printing. By using the paper coated on both sides the number of the dirt particles on handsheet in relation to the removal of particles by flotation, in the described experimental printing substrates used for prints intended for the deinking conditions, decreases drastically (the decrease is about 10 flotation can be seen. There is greater number of particles on times). The brightness of handsheet is in accordance with the handsheet obtained from the fibres of print recycling where the presented results, so higher values were obtained for the prints were made on paper coated on both sides (79,9-86,1 % in recycled fibres of prints made on uncoated paper in accordance relation to D 1,20-2,00). with the concentration of ElectroInk used in printing (D 1,20- The investigation results show that greater handsheet area 2.00 uncoated paper, brightness 91,0-86,8, coated paper, is covered with toner particles when the coated paper was used brightness 86,4-81.0) for printing (27,0-77,3 % in relation to D 1,20 do 2,00). The The removal of ink from the substrate, in deinking process obtained results show that there is the need for particle size depends on characteristics of the printing substrate. With prints analysis according to classes in order to understand the process. made on coated paper there is no contact between ink and fibers. The paper coating disintegrates as the recovered paper is pulped and fragments of the ink film are released. Opposite to the uncoated paper, the adhesion of ink on paper depends on the surface structure, ashes content, fiber types and the mechanism of ink drying in the printing process.

4. CONCLUSION

Based on the investigation results described in the experimental conditions, the following conclusions can be made. By the application of different concentration of ink carrier in liquid ElectroInk, in the process of indirect Fig. 3 Distribution of the dirt particles on the handsheet before electrophotographic printing, the number and the size of toner flotation (the ancoated paper was used for printing, D=1,80). particles on handsheet made from the fibres of the deinking fotation phase can be influenced. The described phenomenon, the type of the substrate, i.e. the coating on paper used in printing is under greater influence. The results justify the creation of statistic models including multifactorial analysis and the determination of the essential conditions in different phases of the indirect electrophotographic printing (voltage of scorotrone, laser strength, voltage of the offset cylinder, concentration of the liquid toner etc.) which leads to the optimization of the deinking flotation process and to obtaining fibres with better characteristics. In this sense, the continuation of these investigations goes on. Fig. 4 Distribution of the dirt particles on the handsheet before flotation (the ancoated paper was used for printing, D=1,80) 5. REFERENCES Bolanca, I., Bolanca Z., (2005). The Optical Properties of Deinked Pulp, Journal of Imaginig Science and Technology, Vol. 49, No. 3, 284-292, ISSN: 1062-3701 Carre, B., (2008). Overview of the Deiking Technology, Final Conference of COST Action E46, Bordeaux, October 2008, Lassus, A. (2000). Deinking Chemistry, In: Recycled Fiber and Deinking, Gӧttsching, L., Pakarinen, H. (Eds.), 241-266, Fapet Oy, ISBN 952-5216-07-1, Jyvӓskylӓ Li, G., Xie,X.F., Wang, A.L., Chen, K.F., (2009). Application of Hydrodynamics in Design of Flotation Deinking Cell, In New Trends in Fluid Mechanics Research, Zhuang F.G., Li J.C., (Eds.), pp.459, ISBN 978-3-540-75994-2, Springer, Fig. 5 Distribution of the dirt particles on the handsheet after Berlin flotation (the coated paper was used for printing, D=1,80) Renner, K., (2000). Deinking Chemistry, In: Recycled Fiber The investigation results on handsheet before print flotation and Deinking, Gӧttsching, L., Pakarinen, H. (Eds.), 241- obtained from the uncoated paper show greater number of 266, Fapet Oy, ISBN 952-5216-07-1, Jyvӓskylӓ particles of greater classes than 0,04mm2, i.e. the particles Zhao, Y., Deng, Y., Zhu, J.Y., (2004). Roles of Surfactants in visible with naked eye in relation to the handsheet obtained Flotation Deinking, Progres in Paper Recycling, Vol 14, No1, (November, 2004) pp 41-45