However, the silicones used in coatings are generally various organically modified polysiloxanes, because the additives used in coatings are generally non-reactive types (except for some products of light-curing systems). The first thing that needs to be solved is the compatibility with various coating systems, but the types and formulations of coatings are very different, the types of resins are also different, and the polarities and HLB values of solvents and water are also very different. How to do it? Compatibility issues must be resolved with organic modification. This is why various organo-modified polysiloxanes are generally used in coatings, which generally have the following characteristics:

◇ Reduce surface tension to improve substrate wetting, flow, leveling and anti-shrinkage crater
◇ Oriented arrangement on the interface of paint and air or ink and air, play the role of smooth, anti-scratch and anti-blocking
◇ It has certain incompatibility with polymers and oligomers, and plays a role in defoaming.

These different types of organo-modified silicone oils, due to their molecular structure, end groups (whether capped or not), the proportion of modified segments and the organic groups in the modified segments, the silicone copolymer will have an infinite number of possibility. Among the copolymers, those with a high proportion of oxyethane (EO) have higher water solubility than those based on oxypropane (PO). The former plays more of a wetting role because it effectively reduces the gas-liquid surface and liquid-solid surface tension, while the latter plays more of a defoaming role because it has the properties of a defoamer, such as limited in the system. Immiscible, especially in those systems that have foam due to the addition of silicone surfactants. Copolymers with high PO content or full PO content are good defoamers in these systems and will not bring Shrinkage defects.

Copolymers containing EO/PO groups at the same time have also been designed as good surface slip additives due to their limited incompatibility. Because in the paint film and ink and varnish system, they can quickly migrate to the surface of the gas-liquid due to such incompatibility during the drying process of the system, so that after drying, the surface is enriched for smoothness, anti-blocking and resistance. grinding action. In the actual packaging industry as well as UV printing inks, this smoothness and low coefficient of friction are significant industry requirements.

However, in general, polyether organically modified copolymers do not bring defects when the drying temperature of the paint film is less than 165 °C, and for those paint film systems that dry at high temperature, other organic modifications, such as polyester and aromatic, should be considered. Modification of alkyl groups.