Naslov
Sodium hydroxide as a developer of lithographic printing plates

Autori
Cigula, Tomislav ; Fuchs-Godec, Regina ; Milčić, Diana ; Donevski, Davor ; Finšgar, Matjaž

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), ostalo

Izvornik
Zbornik referatov in povzetkov / Kaučić, Venčeslav ; Bešter-Rogač, Marija ; Gantar, Marjana - Ljubljana : Slovensko kemijsko društvo, 2016, 1-6

Skup
22. Slovenski kemijski dnevi

Mjesto i datum
Portorož, Slovenija, 28.09.2016. - 30.09.2016

Vrsta sudjelovanja
Poster

Vrsta recenzije
Domaća recenzija

Ključne riječi
printing plates, chemical processing, SEM, surface free energy

Sažetak
Lithography is printing technique in which selective adsorption of printing ink is based on the surface properties of printing and nonprinting areas. It is essential that processes in the plate making are conducted according to defined conditions to enhance hydrophilic properties of the nonprinting areas, to adsorb fountain solution, and hydrophobic properties of the printing areas, to adsorb printing ink. The usual graphic reproduction chain includes various information data manipulation after which the information is transferred onto the printing plate. The transfer of the information onto the printing plate is commonly achieved by at least two processing steps, exposure - the printing plate is irradiated with defined electromagnetic radiation and developing - chemical dissolving of predefined parts of photoactive layer from the printing plate surface. As the developing process is, in majority of the printing plates on the market, conducted in highly alkaline solutions (pH ≈ 12), some producers offered printing plates which exclude developing, but these still lack reproduction quality and endurance in the printing process. Therefore, to reduce bad influence of the developing process, one should determine all process parameters and their influence on the printing plate. The aim of this research was to determine influence of the developing time and developer composition on the surface characteristics of the lithographic aluminium base printing plate. The printing plate samples were processed in NaOH solutions with various molar concentrations of 0.45 moldm-3 (S1) and 0.7 moldm-3 (S2) by altering developing time from 5 to 29 seconds (step of 4 seconds). The printing plate’s surfaces were analysed by Scanning Electron Microscopy (SEM), contact stylus profilometry and determination of the surface free energy by measuring contact angle of referent liquids. Results of the research showed significant influence of both investigated parameters on the surface properties of the printing plates used in this research. Value of the Ra roughness parameter is decreasing with the increase of the developing time for both investigated solution. On plate samples developed in S2 for 25 and 29 s roughness parameters could not be measured as diamond tip damaged the aluminium oxide layer which shows significant decrease in the aluminium oxide mechanical properties. This research has proved that developing process and investigated parameters (concentration of the active substance and developing time) significantly influence nonprinting areas of the lithographic printing plate.

Izvorni jezik
Engleski

Znanstvena područja
Grafička tehnologija, Kemijsko inženjerstvo

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