Abstract
In this paper the influence of the formic and oxalic acids, as substances for dyebath pH adjusting, on the dyeability of polyester fabric dyed with disperse dye Disperse Yellow 23 was examined. The polyester undyed knitwear samples were dyed in baths containing the acids under the same dyeing conditions. Color differences of the samples were assessed using the reflectiometry technique and expressed in terms of CIELcoordinates. The influence of the tested acids on the surface structure of dyed polyester fibers was examined using the scanning electron microscopy (SEM). It was found that the differences in obtained dyeabilities, in the presence of both formic and oxalic acid, are acceptable according to both M&S 83A and CMC (2:1) standards which was not the case with acetic acid. Therefore, acetic acid can be replaced with either formic or oxalic acid as substances for dyebath pH adjusting in the dyeing process described in this paper. SEM micrographs showed small differences in the surface structure of dyed fibers, as well as differences in the shape of undyed samples? reflectance curves in presence of the acids. Since all of the color differences were quite small, it can be concluded that the influence of formic and oxalic acids on the polyester knitwear dyeability is not significantly different than that of acetic acid.
Highlights
Bojenje je započeto na 50 °C i vršeno na toj temperaturi 40 min
Zatim je temperatura flote povećana na 135 °C i održavana na toj vrednosti narednih 60 min
Temperatura je smanjena na 90 °C, a obojeni uzorci pletenine uklonjeni iz flote i isprani toplom vodom (70 °C) koja je sadržala 1 g/L Jugopona 50
Summary
Poliestarski materijali su najčešće korišćeni sintetički materijali zbog odličnih tekstilnih osobina i visoke hemijske otpornosti u tipičnim uslovima bojenja i dorade. Zbog kompaktne i prilično uređene kristalne strukture ovih hidrofobnih vlakana, brzina difuzije boje unutar vlakana je veoma niska [1,2], pa se bojenje vrši na visokim temperaturama (obično 115–135 °C) i pod pritiskom. Poliestarski materijali se boje u slabo kiseloj sredini. Da bi se minimizirala mogućnost hidrolize boje, bojenje se vrši u slabo kiseloj sredini, obično u pH području 4,5–5,5. Za podešavanje pH flote za bojenje najčešće se koristi sirćetna kiselina, mada ima i primera korišćenja pufera koji sadrži mravlju kiselinu i amonijum-sulfat [1,3,5,6]. U ovom radu je ispitan uticaj mravlje i oksalne kiseline na obojenje poliestarske pletenine, bojene disperznom bojom Disperse Yellow 23 (p-phenylazoaniline → phenol) [7,8], kada se ove dve kiseline koriste za podešavanje pH flote za bojenje umesto uobičajene sirćetne kiseline. Uticaj kiselina na morfološka svojstva površine poliestarskih vlakana ispitan je tehnikom skenirajuće elektronske mikroskopije (SEM) [9,10]
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