Utjecaj koncentracije razvijača na parametre hrapavosti površina ofsetne tiskovne forme

Vrkljan, Tomislav (2011) Utjecaj koncentracije razvijača na parametre hrapavosti površina ofsetne tiskovne forme. Diploma work - Pre-Bologna programme. Grafički fakultet. [Mentor: Gojo, Miroslav].

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Abstract

Klasične monometalne tiskovne forme izrađuju se kemijskim otapanjem osvijetljenih dijelova kopirnog sloja u izrazito lužnatim otopinama. Pri tom procesu neminovno dolazi i do otapanja sloja Al2O3 koji se nalazi ispod kopirnog sloja i koji čini slobodne površine na tiskovnoj formi. Sloj Al2O3 kao slobodna površina tiskovne forme dobiven je anodnom oksidacijom aluminija uvjetima da konačno ima izrazito poroznu strukturu, velike specifične površine kako bi mogao brzo adsorbirati dovoljnu količinu otopine za vlaženje tijekom procesa tiska te na taj način onemogućiti prihvaćanje tiskarske boje na te površine. U radu su ispitivane promjene parametara mikrohrapavosti sloja Al2O3 u zavisnosti o koncentraciji razvijač. Do promjena parametara hrapavosti dolazi uslijed djelovanja lužine kao komponente razvijača na oksidni sloj na aluminiju. Aluminij, kao i njegov oksid imaju amfoterni karakter, te procesom razvijanja u izrazito lužnatoj otopini dolazi do njegovog djelomičnog otapanja. Dobiveni rezultati ukazuju da koncentracija lužine značajno utječe na otapanje samog anodnog sloja, a time i na promjenu mikrohrapavosti.

Item Type:	Diploma work - Pre-Bologna programme
Mentor name:	Gojo, Miroslav
Defence date:	9 May 2011
Abstract in english:	The plate making process is composed of two main processes: exposure of the photoactive layer and its chemical processing. The conventional diazo positive as well as most of the CtP lithographic plates has to be developed in a high alkaline solution (pH ≈ 12). During this processing, exposed areas of the photoactive layer are being removed from the nonimage surfaces of the printing plate. It is possible that processing solution dissolves a part of the aluminium-oxide layer too. The aluminium –oxide layer has porous structure with high specific surface which enables it to adsorb optimal amount of the fountain solution sufficient for achieving high quality prints. The aim of this paper was to determine relation between surface roughness parameters measured on aluminium-oxide surfaces and concentration of processing solution. The changes of the roughness of the aluminium-oxide are caused by his as well as aluminium's amphoteric properties (soluble in acid and alkali solutions) which makes it soluble in processing solution during developing process. For the purpose of this research a conventional diazo positive lithographic printing plate was developed in a processing solution with various concentration of sodium base. Obtained results showed that alkali concentration in the processing solution has significant influence on roughness parameters of the nonimage surfaces of the lithographic printing plates. One must take these results into account before plate making process starts. It is important to determine all explored process parameters which are significant for achieving printing plates of high quality.
Uncontrolled Keywords:	kemijsko razvijanje, površinska hrapavost, tiskovna forma
Keywords in english:	chemical developing, printing plate, surface roughness
Subjects:	TECHNICAL SCIENCES > Graphic Technology
Institution:	Grafički fakultet
City:	Zagreb
Number of Pages:	25
Callnumber:	goj 2011 vrk
Inventory number:	D903
Status:	Unpublished
Date Deposited:	15 Nov 2013 21:44
Last Modified:	02 May 2014 08:28
URI:	http://eprints.grf.unizg.hr/id/eprint/1232

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