Pigment & Resin Technology

Purpose – When coatings are applied to industrial equipment, they have to be able to stand the heat produced by solar energy and/or by different conditions on the process. Therefore, the purpose of this paper is to study the effect of temperature on the protective properties of coatings since this parameter degrades the polymer structure. In addition, the temperature effects on dry coating can also be specified.

Design/methodology/approach – In order to know the behaviour of an organic coating at different temperatures, a drying aging cycle was performed by heating on substrate steel and free-of-substrate films during ten uninterrupted days at three and different temperatures: 65, 85 and 100°C. At the end of this period, the aged films were analyzed by means of electrochemical impedance spectroscopy (EIS) measurements, thermal analysis (DSC and TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electronic microscopy (SEM).

Findings – The most critical temperature for the aging was 85°C and “over-cured” phenomenon were observed on the aged films which were reported by EIS, thermal and IR analyses.

Practical Implications – These aging conditions were tested on a very strong and rigid resin containing a barrier pigment. Thus, it can also be applied to other plastic coatings, such as vinyl or alkyd ones, by modifying the temperatures according to glass transition temperature (Tg), as well as the ageing time depending on the hardness and resistance of such coatings and, of course, the protective effect of the pigment. In addition, another aggressive electrolyte, such as synthetic sea water, chloride, sulphide media, as well as inhibitors or ecological pigments could be used in order to predict its behaviour in different corrosive media.

Originality/value – The value of this work is on the specific temperatures used for the aging method applied to a rigid resin which revealed the over-cured phenomena and the behaviour of the pigment; so if it is applied to a more plastic and flexible coating, it may reveal other phenomena and promote other kind of degradation, maybe even more aggressive ones.