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Chemically resistant polyurethane coatings are essential for many industrial applications. They can protect metal fasteners and equipment from corrosion that can cause rust and weaken the structural integrity of the item. A good chemically resistant coating can resist degradation from a variety of chemicals and help prevent costly repairs. There are a few different types of chemically resistant coatings available, each with its own benefits and drawbacks.
Some are epoxy-based and offer excellent impact resistance, while others, like polyurethanes, are often used for their superior abrasion and corrosion resistance properties. There are also waterborne urethanes, sometimes called latex-based, that cure in the presence of moisture. There are also aromatic urethanes that are cured using aromatic isocyanates such as MDI and TDI along with polyether polyols. While these types of urethanes are very durable, they tend to discolor when exposed to UV light and their performance may degrade over time due to oxidation.
Guardians of Durability: Unraveling the Strengths of Chemically Resistant Polyurethane Coatings
Fortunately, there are aliphatic urethanes that use a combination of aliphatic isocyanates and polyether polyols that do not degrade due to exposure to sunlight. This type of chemistry, combined with a proper blending of reactivity with the polyols, results in a cured material that offers superior performance in terms of both abrasion and chemical resistance.
A key to a well-formulated aliphatic polyurethane is the correct film mil thickness. Too thin and the UV radiation can penetrate past the protective aliphatic cross-links. Too thick and you run the risk of polymer shrinkage cracks that can compromise the durability of the coating.