Utjecaj lužine na površinska svojstva aluminijevog oksida

master's thesis

• Author: Katarina Gojo
• Mentor: Sanja Mahović Poljaček (mentor)
• Committee member: Sanja Mahović Poljaček (član povjerenstva)
• Granter: University of Zagreb; Faculty of Graphic Arts; Zagreb
• Defense date and country: 2010-9-30, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Graphic Technology

Abstract

Zavisno o koncentraciji razvijača određivani su parametri površinske hrapavosti, kontaktni kut,

te slobodna površinska energija (SPE) na Al2O3 kao materijalu slobodnih površina tiskovnih

formi za ofsetni tisak. Kao razvijač upotrijebljena je vodena otopina NaOH različitih

koncentracija, a kao standardi za mjerenje kontaktnog kuta i SPE korišteni su dijodmetan,

glicerol i voda.

Djelovanjem NaOH na površinu Al2O3 dolazi do njegovog otapanja, te tako, na određeni način i

do poliranja površine što pokazuju izmjereni parametri hrapavosti. Smanjenje Rp i Rv vrijednosti

ukazuje na promjenu hrapavosti površine. Prevlaka anodnog sloja je manje hrapava, a time se

smanjuje broj aktivnih točaka za adsorpciju molekula otopine za vlaženje.

Zavisno o upotrijebljenom standardu kontaktni kut na slobodnim površinama se u početku

smanjuje povećanjem vremena razvijanja, da bi kasnije dolazilo do njegovog povećanja.

Produljenje vremena kemijskog djelovanja otopine NaOH svih ispitivanih koncentracija najprije

uzrokuje neznatno povećanje slobodne površinske energije, a kasnije njeno smanjenje.

Udio disperzne faze slobodne površinske energije kod svih uzoraka gotovo je nepromijenjen

neovisno o vremenskom intervalu izlaganja djelovanju otopini razvijača, dok polarna faza

pokazuje slično ponašanje, odnosno, raste do postizanja maksimalne vrijednosti, nakon čega se

smanjuje.

Abstract (english)

Parameters of surface roughness, contact angle and surface free energy (SFE) on Al2O3 as a

material wich is used as the non-image areas for the offset tehnique has been determined

depending on the concetration of the developing solution. Different concentration of NaOH

water solution has been used as the developing solution, and diiodomethane, glycerol and water

were used as standars for measuring the contact angle and surface free energy.

NaOH solution has caused the dissolution of Al2O3 surfaces during the developing process. By

dissolution of Al2O3 peaks of the nonprinting elements the platous has been formed and could be

dectected by measuring the surface roughness parameters. Decreasing of Rp and Rv values have

indicated the changes in surface roughness. The anode layer had lower vaues of roughness which

caused the reducing of the number of acticve points for the adsorption of fountain solution.

Depending on the used standard, contact angle values on the non-image areas initially have been

decreased with increasing of development time, but with certain increase in later stages. Longer

development in all concentrations of NaOH has caused a slight increasing of SFE in the first

stages with certain decrease in the later stages.

The disperse components of SFE on all observed samples of plates has been unchanged

regardless of the developing duration. Similar results have been detected with the polar

components where the values have been increased in the first stage followed by decreasing in the

other stages.

• Keywords: kontaktni kut; površinska hrapavost; slobodna površinska energija; tiskovna forma
• Keywords (english): contact angle; surface free energy; printing plate; surface roughness
• Language: croatian
• URN:NBN: urn:nbn:hr:216:746559
• 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 09:46:42