Contribution of inorganic pigments to the formation of paint films from oxypolymerising drying paints

Abstract

Purpose

The paper aims to investigate the drying effect exhibited by pigments combined with a Co(II) salt of 2‐ethylhexanoic acid (Co(II)) in an alkyd resin modified by soya bean oil.

Design/methodology/approach

Paint hardening was studied by means of a method that follows the progress of alkyd film drying. Another important method was employed to monitor the gradually increasing hardness of the drying films. Hardness of thin films was measured by the Persos method. ZnO, ZnO nanoparticles, V₂O₅, ZnS and TiO₂ were used to study the effect of solid inorganic pigments on alkyd film drying. The pigment particles were characterised by scanning electron microscopy. The investigated pigments were combined with a constant amount of the Co(II) drier that acts in the system as a homogeneous catalyst, while the investigated pigments played the role of heterogeneous catalysts.

Findings

Using certain pigments as catalysts in drying, alkyd resins brings about new findings concerning the function of fillers and pigments in paint films. ZnO nanoparticles substantially accelerate film drying and moreover, the resulting films exhibit substantially higher hardness than films containing other inorganic pigments. To prepare films exhibiting higher hardness within a shorter time, one may also use ZnO microparticles or ZnS. TiO₂ and V₂O₅ were identified as pigments that either do not take part in the drying process or reduce the hardness of the resulting film.

Practical implications

The investigated catalytic system pigment/Co(II) drier can be advantageously used to accelerate the formation of alkyd paints modified by natural oils both for industrial and decorative purposes. It was established that hardness of paint films containing ZnO nanoparticles is twice as high as that of films containing only the Co(II) drier without any pigment. This finding makes new applications of alkyd paints possible in all instances where higher hardness is required.

Originality/value

Considering pigments as heterogeneous catalysts in systems producing films by the oxypolymerising mechanism is a new approach that gives rise to new and original solutions.

Citation

Kalendová, A., Veselý, D. and Kalenda, P. (2010), "Contribution of inorganic pigments to the formation of paint films from oxypolymerising drying paints", Pigment & Resin Technology, Vol. 39 No. 5, pp. 255-261. https://doi.org/10.1108/03699421011076353