The colour stability of natural dye coating films consisting of chlorophyll after exposed to UV-A. Issue 3 (3rd May 2016)

• Record Type: Journal Article
• Authors: Usop, R.; Abidin, Z.H.Z; Mazni, N.A.; Hadi, A.N.; Halim, N.A.; Taha, R.M.; Careem, M.A.; Majid, S.R.; Arof, A.K.
• Is Part Of: Pigment & resin technology. Volume 45:Issue 3(2016)
• Page Start: 149
• Page End: 157
• Publication Date: 2016-05-03
• Subjects: Chlorophyll -- CIEL*a*b* -- Colour stability -- Natural dye coating film; Protective coatings -- Periodicals; 667.62305
• DOI: 10.1108/PRT-10-2014-0097
• Languages: English
• ISSNs: 0369-9420

Abstract

Abstract : Purpose: This paper aims to study the colour stability of chlorophyll and the effect of copper (II) nitrate – Cu(NO3 )2 – as an additive in natural dye coating films after being exposed to ultraviolet-A (UV-A). Design/methodology/approach: The natural dye was extracted from the leaves of Cassia alata L. using absolute ethanol as the solvent. The extract was divided into two parts and, one of it was added with 3 wt.% Cu(NO3 )2 as an additive. The polymer blend of poly(methyl methacrylate) (PMMA) and acrylic polyol was used as the coating binder. Both parts of the dye with and without additive were mixed with the blended polymer in a specific ratio. The resulted mixtures were applied as coating films on glass substrates. The colour stability of the coating films on exposure to UV-A with the time of exposure was observed with Commission internationale de l'éclairage (CIE) L*a*b* colour coordinates. The hidden power by the means of reflectivity and glossiness of the coatings was also studied. Statistical standard deviation (STD) was used to analyse the data. Findings: The test showed that the coating films containing Cu(NO3 )2 had smaller colour differences, (ΔE*) indicating higher colour stability. The analysis on hidden power also showed that the coating film with Cu(NO3 )2 was 1.6 times more stable than the film without additive. All the measurements in this study were observed within 35 days of duration. Research limitations/implications: This paper implies the potential of using natural dye extracted from Cassia alata L . leaves as a stable dye colourant for coating applications. Practical implications: The coating film developed in this study is suitable for glass substrate applications. Originality/value: A new method of preparing solvent-based coating film from PMMA–acrylic polyol with chlorophyll colourant is introduced in this study.