Doprinos optimiranju kvalitete novinskog papira

Lozo, Branka (2004) Doprinos optimiranju kvalitete novinskog papira. Master's thesis - Pre-Bologna programme. Grafički fakultet. [Mentor: Golubović, Adrijano].

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Abstract

Upotreba otpadnog papira kao izvora sirovine za ponovno korištenje celuloznih vlakana nalazi sve širu primjenu u području izrade tiskovnih papira. Novinski papir se dijelom proizvodi od već korištenih vlakana otpadnih novinskih otisaka. Jedan od ključnih postupaka u procesu reciklacije je deinking flotacija kojom se odvajaju i uklanjaju čestice tiskarske boje iz razvlaknjene pulpe. Reciklacijom se celuloznim vlaknima mijenjaju svojstva, ona postaju kruća, krtija, manje fleksibilna i lomljiva, a smanjuje im se i sposobnost bubrenja. Time se smanjuju površine međusobnih kontakata vlakana, a slabe i vodikove veze neđu njima. Zbog toga su mehanička svojstva papira iz reciklairanih vlakana slabija od onih iz primarnih vlakana. U proizvodnji novinskog papira poboljšanje mehaničkih svojstava je dijelom razlog za dodavanje otisaka na papiru iz primarnih vlakana. U ovom radu istražena su mehanička svojstva laboratorijskih listova dobivenih reciklacijom postupkom kemijske deinking flotacije otisaka konvencionalnog i digitalnog ofsetnog tiska na različitim tiskovnim podlogama i u različitom udjelu. Korišteni su otisci konvencionalnog ofsetnog tiska na novinskom papiru uz dodatak različitih udjela otisaka digitalnog ofsetnog tiska na premazanom i nepremazanom papiru. Rezultati istraživanja pokazuju da se indeksi kidanja, cijepanja i prskanja takvih listova kontinuirano smanjuju porastom udjela digitalnih otisaka u sastavu recikliranih listova. Također se povećava broj vidljivih zaostalih čestica ElectroInka sa digitalnih otisaka. Prisutnost punila i čestica boje koje se nisu izdvojile iz pulpe flotacijom uzrokuju smanjenje mehaničkih svojstava. Izrada laboratorijskih recikliranih listova od nepremazanih papira s digitalnim ofsetnim otiscima u nastavku istraživanja vodi k raščlanjivanju kompleksnog utjecaja punila i čestica zaostale boje. Opetovano smanjenje indeksa kidanja, cijepanja i prskanja laboratorijskih listova u čijem sastavu je utjecaj punila neznatan, upućuje na zaključak da je za smanjenje mehaničkih svojstava prvenstveno odgovorno zaostajanje čestica ElectroInka koje svojom prisutnoščću ometaju međusobno vezivanje vlakana kao osnovnog preduvjeta mehaničke čvrstoće papira. Zaključuje se da konvencionalna kemijska deinking flotacija nije dovoljno uspješna metoda za reciklaciju digitalnih ofsetnih otisaka, te se javlja potreba za daljnjim istraživanjem u ovom području, pogotovo kada bi se u masi otisaka za reciklaciju koristilo više od jedne trećine udjela otisaka digitalnog ofsetnog tiska.

Item Type: Master's thesis - Pre-Bologna programme
Mentor name: Golubović, Adrijano
Thesis Committee: Bolanča, Stanislav and Turkulin, Hrvoje and Parac-Osterman, Đurđica and Bolanča, Zdenka and Golubović, Adrijano
Defence date: 10 February 2004
Abstract in english: The use of waste paper as a source of raw material for the re-use of cellulose fibers plays an increasing role in the production of printing paper. Newsprint paper is partly produced from used fibers obtained from waste newsprints. One of the key procedures in the recycling process is the deinking flotation by means of which the printing ink particles are removed from defibrated pulp. Recycling changes the properties of cellulose fibers: they become harder, more brittle, breakable, less flexible and their swelling capacity is reduced. In consequence, the contact surface between the fibers is reduced and hydrogen bonds between them grow weaker. Therefore, the mechanical properties of paper from recycled fibers are inferior to those produced from primary fibers. The improvement of mechanical properties is one of the reasons for the inclusion of prints on paper from primary fibers in the production of newsprint paper. This study focused on the mechanical properties of laboratory handsheets obtained by recycling standard and digital offset prints on different substrates. The chemical deinking flotation was used. The proportion of conventional and digital offset prints in the mixture, both coated and uncoated, was varied for each study batch. The obtained results show that the tensile, tear and burst indices of such handsheets continuously fall with the increase of the share of digital offset prints in the recycling mixture. At the same time, there is an increase in the number of visible particle residues of ElectroInk from digital offset prints.The reduction of mechanical properties is explained by the presence of fillers and ink particles which did not separate from the pulp in flotation. The production of laboratory recycled sheets from uncoated digital offset prints in the next phase of the experiment provided insight into the complex influence of fillers and remaining ink particles. A repeated fall in the tensile, tear and burst indices of handsheets in whose content the influence of fillers is marginal leads to the conclusion that the remaining particles of ElectroInk are chiefly responsible for the reduction of mechanical properties. Their presence interferes with the interlinking of fibers – the basic prerequisite of paper’s mechanical strength. The conclusion of the experiment is that the conventional chemical deinkng flotation is not efficient enough to recycle digital offset prints. This observation calls for further researches in this field.
Uncontrolled Keywords: reciklirana vlakna, konvencionalni ofsetni tisak, digitalni ofsetni tisak, kidanje, cijepanje, prskanje, punila, čestice boje
Keywords in english: recycled fibers, conventional offset printing, digital offset printing, tensile, tear, burst, fillers, ink particles
Subjects: TECHNICAL SCIENCES > Graphic Technology
Institution: Grafički fakultet
City: Zagreb
Number of Pages: 124
Callnumber: 676.017 loz m
Inventory number: 7369
Status: Unpublished
Date Deposited: 15 Nov 2013 21:47
Last Modified: 14 May 2014 12:09
URI: http://eprints.grf.unizg.hr/id/eprint/1455

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