Utjecaj koncentracije razvijača na parametre hrapavosti površina ofsetne tiskovne forme

master's thesis

• Author: Tomislav Vrkljan
• Mentor: Miroslav Gojo (mentor)
• Committee member: Miroslav Gojo (član povjerenstva)
• Granter: University of Zagreb; Faculty of Graphic Arts; Zagreb
• Defense date and country: 2011-5-9, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Graphic Technology

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.

Abstract (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.

• Keywords: kemijsko razvijanje; površinska hrapavost; tiskovna forma
• Keywords (english): chemical developing; printing plate; surface roughness
• Language: croatian
• URN:NBN: urn:nbn:hr:216:856073
• Study programme: Title: Graphic technology; specializations in: Graphic technology, Design of graphic products; Course: Graphic technology; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra inženjer/inženjerka grafičke tehnologije (sveučilišni/a magistar/magistra inženjer/inženjerka grafičke tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2024-04-17 09:28:27