Transparent iron oxide pigments, traditionally used in the production of silver and gold, create a reputation among consumers. In the current car styling recipe, the depth of shadow and transparency is very important. Transparent iron oxide not only meets these color requirements, but also has weatherability, low cost and attractive UV absorption characteristics.

　　The characteristics of concentration, beautification and protection are essential in automotive modification. Low cost, transparent iron oxide pigments are manufactured to ensure that the colors are clean and consistent. The inherent characteristics of iron oxide absorbing ultraviolet radiation and the ability to make products into colored transparent materials make it particularly important for vehicle coloring. In this article, we will introduce these roles, as well as the scattered features and styles.

　　Pigment characteristics

　　The manufacturing method of transparent iron oxide pigment allows for controlling the physical and surface chemical properties of primary particles. Optimize the granularity to ensure minimum optical interference and maximize transparency. However, the result of small particle size is high surface area and oil absorption value, similar to organic pigments.

　　Different systems and supplementary pigments often require different surface chemistry. Therefore, the surface chemical properties of transparent iron oxide particles in the manufacturing process are allowed to have different compatibility and stability in the coating formulation. For example, the acid grade is not recommended for use with water-based systems, because chemical equilibrium will be destroyed and resin precipitation. Conversely, in solvent based formulations, highly charged acidic pigments tend to produce excellent properties. This leads to a series of colors with different performance characteristics. In view of this, it is important to understand the application so that appropriate pigments can be selected.

　　Dispersing process

　　In order to achieve the nanoparticle diameter of transparent iron oxide, a manufacturing method that leads to aggregation and aggregation increases is used. In order to completely disperse pigment, high level of shear and energy is needed. For a relatively low viscosity system, ball mills or grinders can be used, but ball mills with glass, steel or zirconia media are preferred. Two or three roller mills may be required when high viscosity formulations (such as paste or highly colored concentrates) are required. High speed mixing with Cowles blade will not provide enough shear force to disperse transparent iron oxide pigments.

　　Although most automotive coatings are produced internally, the time and difficulty of dispersing transparent iron oxide cause these dispersions to be produced by special dispersions. Once the pigment is completely dispersed, the particle size makes the colloidal suspensions stable and good tank stability. This is not the case for larger dense particles. Usually additional stability is required in the formulation by using rheology and / or charge regulator.