| Protective coating is one of the most important application area among the industrial coatings. Because of the excellent anti-corrosive performances, excellent adhesion on both steel and concrete substrates, epoxy coatings have become the most widely used generic primers for protective coatings. Currently the solvent based epoxy coating is still dominated in heavy duty coatings and in the domestic market the common SB epoxy coating’s volume solid is generally in the range of50～70%and emit lot of VOC pollutants during the applications. It has became the market trend to develop the environmental friendly coating technology.There are three approaches including powder coating, high solid and Water-based coatings to achieve environmental friendly epoxy coatings. For the better application convenience, high solid epoxy coatings and water-based epoxy coatings are preferred for ambient curing protective coating applications.It was decades years ago that high solid epoxy coating had been developed out.But the old technologies have some significant disadvantages like short port life, drying slowly,poor toughness,short over-coating windows as well as high cost which limit the high solid coatings acceptance in the market. Another effective approach to reduce VOC is water-based (WB) epoxy coatings. Water-based coatings can have a very low VOC or even VOC free. But for WB epoxy coatings,it has such weaknesses:inferior anti-corrossive performances, short shelf life and so on.This paper studied effects of hybrid of the epoxy resin/curing agent/other components on final coatings performances, and two types of environmental friendly epoxy anti-corrosive coatings,high solid epoxy coatings and water-based epoxy coatings were successfully prepared with excellent balanced performances by hybrid modification on epoxy resin system. The detailed contents are as following:(1) A high solid epoxy coating is prepared utilizing low molecular standard BPA LER (EP) and a reactive dilluent mixture curing agents of polyamide and phenalkamine, in which the epoxy resin is modified with hybrid of vinyl resin. The prepared high solid epoxy coating has significantly improved the traditional epoxy coatings to get better flexibility,low temperature applicability and long over-coating windows.(2) A water-based epoxy coating is prepared based on a novel epoxy dispersion which has non-ionic surfactants with epoxy functionality and small dispersion particle size. The different types curing agents/coalescent solvents/silicone coupling agents/anti-corrosive pigment were studied on the effects of the anti-corrossive performances. The new WB epoxy coating has excellent anti-corrove performances and is recommended for general metal protection above water. |
PDF Full Text Request