Coloration of aluminum pigment using SiO₂ and γ-glycidoxypropyltrimethoxysilane with dichlorotriazine reactive dye

Abstract

Purpose

The purpose of this paper is to colour aluminium pigment to the highest chroma using SiO₂ and organic silane with dichlorotriazine reactive dye and investigate its reaction mechanism, chemical stability and thermal properties to improve its applicability in surface coatings.

Design/methodology/approach

Aluminium pigment was encapsulated by the catalysed sol-gel method using SiO₂, followed by modification with γ-glycidoxypropyltrimethoxysilane (GPTMS). Purified reactive dye (1-Amino-4-[3-(4,6-dichlorotriazin-2-ylamino)-4-sulfophenylamino]anthraquinone-2-sulfonic acid (X-BR)) was covalently immobilized onto modified SiO₂ to obtain coloured aluminium pigment. The reaction mechanism, chemical stability and thermophysical properties were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope, transmission electron microscope and thermogravimetric analyses (TGA).

Findings

The results showed that X-BR was covalently attached to modified Al/SiO₂ with maximum colour grafting of 95 per cent when the dosage of GPTMS and X-BR per weight of modified Al/SiO₂ was 25 and 15 per cent, respectively, at pH 8.5 and a temperature of 40°C. The coloured aluminium pigment had good chemical stability with excellent anti-migration properties in many solvents.

Research limitations/implications

The organic silane used required a careful control of pH to ensure maximum colour grafting efficiency meanwhile other silanes with amine groups could also be used effectively with different kinds of colorants besides reactive dyes.

Practical implications

The method used is less cumbersome and provides a simple route to preparing coloured aluminium pigment.

Originality/value

The use of organic-inorganic SiO₂/γ- GPTMS with purified reactive dye to covalently colour aluminium pigment to the highest chroma is novel and will help advance the frontiers of knowledge on coloration of aluminium pigments.

Citation

Tawiah, B., Zhang, L., Tian, A. and Fu, S.S. (2016), "Coloration of aluminum pigment using SiO₂ and γ-glycidoxypropyltrimethoxysilane with dichlorotriazine reactive dye", Pigment & Resin Technology, Vol. 45 No. 5, pp. 335-345. https://doi.org/10.1108/PRT-07-2015-0063