Solvent-free epoxy coating is a low-pollution replacement product for solvent epoxy coating, and has better unique product performance. The organic solvent in the solvent-free coating is quite small, and the volume solid content is 98%~100%. Solvent-free epoxy coatings are often used as lining coatings on the inner walls of storage tanks, water pipelines, storage tanks, etc., or heavy-duty anti-corrosion applications for large steel structures such as offshore platforms and water conservancy facilities. Solvent-free epoxy glass flakes have better corrosion resistance, and solvent-free phenolic epoxy coatings have better high-temperature resistance.
Compared with solvent-based epoxy coatings, solvent-free epoxy coatings have the following characteristics:
(1) The edge-covering solvent-free epoxy coating has , while the solvent-based epoxy paint will shrink on the edge of the steel due to the volatilization of the solvent, resulting in thinning of the paint film. Reduce the anti-corrosion effect. This is also one of the main reasons why we often see the edge of the profile corroded first, but the plane is intact.
(2) No shrinkage, no elongation Solvent-free epoxy does not shrink during curing, and the coating does not elongate after drying, which is the main feature of the durability of solvent-free epoxy coatings. When the solvent-based epoxy coating is dry, it will crack due to the volatilization of the solvent, while the non-shrinkage of the solvent-free epoxy makes it less prone to cracks when it encounters uneven steel plates.
(3) Construction safety Since ordinary solvent-based epoxy coatings contain more than 40% volatile organic solvents, even high-solid epoxy coatings have more than 20% volatile organic content (VOC). A large amount of organic solvents have brought a lot of safety, hygiene and environmental protection problems to the use of coatings. There are a lot of open flame operations in the manufacture of steel structures, so it is necessary to avoid open flame operations during coating construction, or wait until the coating operation is completed and the explosion test is qualified before proceeding, and the time to stop open flame operations depends on the length of the solvent volatilization process and ventilation conditions. The use of solvent-free epoxy coatings can greatly reduce this time due to the small amount of volatile solvents, which brings convenience to the production arrangement of steel structure manufacturing. In addition, most organic solvents are poisonous and harmful substances, which have different degrees of poisonous effects on the human body. In order to ensure the health of construction workers, it is necessary to limit their content in the air. The higher the organic solvent content in the paint, the more fresh air needs to be supplemented, that is, the greater the ventilation required. For some closed parts, such as ship cabins and petrochemical storage tanks, etc., the use of solvent-free epoxy coatings means that this part of the ventilation can be reduced.
(4) Environmental protection It should be emphasized that the most prominent advantage of using solvent-free epoxy coatings is that it can reduce the air pollution caused by the volatilization of organic solvents. In heavy-duty anti-corrosion coatings, solvent-free and water-based coatings will be the future development direction, and solvent-free epoxy coatings are more practical under the current conditions.
5) Thick film type construction Solvent-free epoxy coating can be thick film type construction, spraying once can reach 150~400ยต.m, or even higher dry film thickness. This greatly saves construction time. For the integrity of the paint film and to avoid defects in one construction, it is recommended to apply two coats of paint to achieve the specified dry film thickness.
