Surface modification of mica powder and its application in industrial anti-corrosion coatings
Mica has excellent chemical inertness, so it can improve the corrosion resistance of coatings such as neutral salt spray resistance, acid resistance, alkali resistance, etc. At the same time, with its unique lamellar structure, it can adjust the internal stress of the coating and improve the continuity and density of the coating film. It can effectively slow down the penetration of corrosive substances in the coating film and alleviate the corrosion of steel substrates. Adding mica to anti-corrosion coatings can significantly improve the corrosion resistance of coatings.
However, like many natural minerals, mica has a hydrophilic and oleophobic surface, and is difficult to wet and disperse in the organic phase. Due to its large specific surface area and high oil absorption, it is difficult to achieve high filling in the coating system and is compatible with the resin in the coating. Poor performance, unsatisfactory interfacial bonding, and easy flocculation. In order to change this phenomenon, at present, various coating companies mainly add different additives directly in the coating production process, but this method will cause waste of additives, and the dispersion effect is not good, causing the anti-corrosion performance of the coating to fail to meet expectations.
Therefore, in order to give full play to the function of mica, so that the mica can be uniformly dispersed in the coating system, and can form a stable interface with the coating resin after curing, so as to improve the performance of the anti-corrosion coating, it is possible to consider pre-treatment and surface modification of the mica, and then Add it to the coating system.
The surface of mica powder was modified by silane modifier, and the actual functional performance of mica powder before and after modification in the field of industrial anti-corrosion coatings was explored. The results show that:
(1) The use of silane modifier to modify mica powder can significantly improve the application performance of mica in the coating system. The optimum amount of modifier is 1.5%.
(2) The modified mica powder is better than the unmodified mica powder in improving the production efficiency and application performance of the coating system. With the increase of the amount of mica powder added, the viscosity of the system tends to increase due to the increase of oil absorption, and the time for the decrease of fineness will be prolonged, which has a negative impact on the production and efficiency. Compared with the unmodified product, the influence of modified mica powder on the viscosity of the system is significantly reduced, which can improve the production efficiency and system viscosity.
(3) The addition of mica powder has no obvious adverse effect on the physical properties of the coating film.
(4) When the addition amount of mica powder is less than 5%, the anti-corrosion performance of the coating film is slightly poor. Within a suitable range, the larger the addition amount, the better the anti-corrosion performance.
(5) Comprehensive production efficiency and anti-corrosion performance, in industrial anti-corrosion coatings, the reasonable addition amount of unmodified mica powder is 8% to 12%, and the reasonable addition amount of modified mica powder is 10% to 15%. the best overall performance.