Protective epoxy dispersion coating materials modified a posteriori with organophilized montmorillonites

Two types of paints (primer and topcoat) and coatings based on epoxy resin dispersions, water solution of polyamine hardener and a posteriori introduced four types of organophilized montmorillonite (mMMT) nanofillers: two commercial Nanofil-type (used as powders) and two pilot plant NanoBent-type products (in a powder and water-slurry form) were formulated and investigated. Pulverized organoclays were preliminarily incorporated (in various doses: 1, 2.5 and 5 wt.%) into the epoxy resin dispersions, filled mainly with iron oxides (primer) or the TiO2/white filler (topcoat) using either a pearl-mill or a dissolver. Water-slurry of semihydrophilic modified montmorillonite was mixed with epoxy resin dispersions in the dissolver. The paints were applied on steel substrate and cured at room temperature. An influence of the method of introduction, handling form and type of mMMT on properties of epoxy dispersion paints and coatings has been investigated. In most cases coatings with semihydrophilic NanoBent-type nanofillers exhibited better properties than those with hydrophobic mMMT. Differences of barrier and mechanical features for primer, topcoat and primer/topcoat (multilayer) coatings based on results of water uptake, relative impedance, adhesion to steel, hardness and abrasion resistance tests, are discussed.