Obtenção e caracterização de tintas em pó base epóxi/poliéster com incorporação de argilominerais : montmorilonita (MMT) e mica muscovita

Abstract

One of metallic substrates protection systems most commonly used in the industry is the paint. Factors favorable to the use of powder coatings include non-use of solvents, processing facilities/application and the possibility of reuse of material that did not adhere to the surface of the pieces. The thermal, mechanical and chemical characteristics of the obtained paint are influenced principally by the type of resin used. Hybrid (epoxy/polyester) powder coatings aimed at reconciling the weathering resistance characteristic and action of UV rays with the chemical resistance and mechanical characteristics. In the powder coatings can be added nanofillers which aims to improve the thermal, mechanical and chemical coatings. Another feature of nanofillers is the low financial cost resulting from the use of a lesser amount of filler, with a high level of performance. Among the nanofiller used, it can be cited muscovite mica and montmorillonite 30B (MMT 30B) that, when incorporated into the coatings, even at low concentrations, have higher barrier properties than conventional fillers. This work aims to develop and characterize a hybrid powder coating containing different amounts of muscovite mica and MMT 30B. Clayminerals have been incorporated in a standard formulation hybrid powder coatings in proportions of 2, 4 and 6% (w/w). Before applying the coating, the metal substrates were subjected to a pretreatment phosphating with zinc phosphate. After this, the powder paint was applied to panels with dimensions 70 x 120 x 0.65 mm carbon steel AISI 1010 through electrostatic spraying. The clayminerals, the powder paint and coating were analyzed using various characterization techniques, such as particle size analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy in Fourier transform (FTIR) and scanning electron microscopy for field emission (SEM-FEG). The effect of the incorporation of clayminerals in the physical properties and corrosion protection of coatings was evaluated with brightness measurement tests, adhesion, flexibility, impact resistance, electrochemical impedance spectroscopy (EIS), exposure to fog saline (NS) and flame test. For all coatings containing clayminerals was found to increase the surface hardness of the coating and reduced gloss with increasing clay content, this being more pronounced effect with the addition of 6% (w/w) of MMT 30B. The adhesion of the coating to the substrate was not altered by the presence of clayminerals. The coatings containing mica muscovite showed better results in impact resistance tests and flexibility when compared to coatings containing MMT 30B. The sample TH/6/MICA showed better results in the electrochemical impedance test in relation to other systems studied. In the salt spray test all samples showed high corrosion protection. There were no blistering or corrosion spots on the surface of any of the samples. However, in the subsequent test of subcutaneous migration, the sample TH/2/MMT 30B showed the greatest peeling. In the flame test, coatings with incorporation of muscovite mica showed better results than coatings with MMT 30B. After analyzing all the tests, it is concluded that the addition of muscovite mica in the proportion of 4% resulted in an paint with improved thermal, mechanical and chemical properties.