From a formulation standpoint sealants and adhesives use very similar raw materials: they always contain a binder/polymer, filler(s), crosslinkers, catalyst and additives (UV-stabilizer, pigment, adhesion promoter….).
The major distinction between a sealant and an adhesive is the intended use:
- In case of a sealant the material should fill a gap or void between two materials and be able to accommodate the movement of the two materials resulting from thermal expansion or contraction, hereby guaranteeing the integrity of the surface and preventing e..g the ingress of water. For the sealant to function properly it at least needs to have good adhesion to the materials combined with a intrinsic medium strength (medium to low modulus) beyond any other application specfic property.
- In case of an adhesive the material should bond two materials together. For this the material needs to have excellent adhesion to the substrates combined with a high intrisic strength (high modulus and high tensile), again beyond any other application specific property.
While the strength of an adhesive or sealant is for a large part being determined by the polymer/resin being used, the skilled formulator can even further optimise the overall performance of the sealant/adhesive (including the application specific properties) by selecting the proper fillers at the right amount.
Sibelco offers a wide range of mineral fillers to the “tool-box” of the skilled formulator to provide:
- Dimensional stability (ATH, Silica, Cristobalite, Huntite Nepheline Syenite and Wollastonite)
- Flame retardancy (ATH and Hydromagnesite)
- Rheology modification (Hydromagnesite and Huntite)
- Chemical resistance (Silica, Barite, Cristobalite, Nepheline Syenite and Wollastonite)
- Colour/ whiteness (Cristobalite)
- Mechanical properties (Silica, Wollastonite)
- UV resistance
- Cost efficiency