The auxiliaries used in coatings are mostly surfactants, which can be achieved by reducing the surface tension of gas-liquid, liquid-solid or gas-solid interfaces The effect of leveling, defoaming, dispersing and improving adhesion. Silicone compounds have low surface tension, high surface activity, It has a wide range of applications in coating system and is an important variety of coating additives.
1：The silicone auxiliaries used in the coating system can be divided into two categories: silane and silicone oil, Silanes are mainly small molecular compounds used as adhesion promoters, crosslinkers and dispersions in coatings Agent, etc.; The main components of silicone oil additives are modified silicone oil. By adjusting the relative molecular mass of additives, the type and content of modified group R And the functional groups of the end groups, can get a variety of different properties of auxiliaries.
2 As a silicone agent for coating antifoaming agent
As an antifoaming agent for coatings, it is usually required to have a lower surface tension than the applied system and at the same time to be incompatible with the applied system. Organic silicon by
Because of its low polarity structure, it is not compatible with most coating resin systems, so it is widely used as the raw material of coating antifoaming agent. Usually, the relative molecular weight of the large (10000 ~ 100 000) polymethylsiloxane can be used as a coating defoamer. At present, this kind of defoaming agent is widely used in heavy anticorrosion system. In order to improve the efficiency of defoaming, some white carbon black can also be added as a synergism Components. In addition, because the defoaming efficiency of silicone is high, it has a good effect at a very low amount of addition, in order to facilitate the addition, usually The silicone defoaming agent was prepared into a low concentration solution to meet the needs of practical production. In the solvent-based coating system, in order to enhance the defoaming ability of the coating, fluorocarbon is used to modify organosilicon through the organosilicon backbone
The introduction of fluorocarbon chain segments with lower compatibility and surface tension can further reduce the compatibility between the coating and the system, and greatly improve the effect of defoaming The longer the fluorocarbon chain is often introduced, the better the defoaming effect is. This kind of defoaming agent is usually a high-end variety of silicone defoaming agent.
3 Organic silicon substrate wetting agent
Because the surface tension of water in water system is too large, it is difficult to wet the substrate (especially the substrate with low surface tension) quickly In waterborne coating system, the use of substrate wetting agent is particularly important. Silicone based wetting agent due to its wide applicability in waterborne coatings The system has been widely used.