Silicone elastomers are comprised of thermoset gum rubber, one- and two-component RTV systems and two-part LIM systems. Selection of a colorant must be made to meet the individual requirements of a specific type.
RTV Compounds
Most commonly used for sealants and caulks, there are two types of RTVs: one-component moisture-cured systems and two-component systems. Stan-Tone™ SP (silicone paste) colors offer a standard line of single pigments dispersed in a low-viscosity dimethyl fluid. They can be modified to varying viscosities, from pourable fluid to thick putty. The SP line excels at providing custom-blended, multi-pigment colors.
LIM System
The LIM system consists of two pumpable components with a platinum catalyst to speed up the cure. The colorant and other additives are often added via a third mixing head. The colorant must be pumpable and non-settling. The Stan-Tone SP line offers custom-made colors using a vinyl-terminated, reactive silicone specially developed for LIM systems. Pigments containing residual sulfur should be avoided because they can interfere with the platinum catalyst. Many applications require non-toxic pigments.
Key Characteristics
PolyOne colorants can be selected to meet any or all of the following characteristics:
- Indoor or outdoor light-fastness
- Chemical resistance
- Heat stability
- Ease of dispersion
- Toxicity
- Optimum economics
- Heavy-metal replacement