High elasticity and stability for long lasting solutions
Sealants (low modulus)
A low modulus sealant is defined as an elastomeric material with a modulus at 100 % elongation of up to 0.4 MPa. This property can be obtained simply by the addition of an appropriate plasticizer. However, being non-reactive and not chemically anchored into the formulation, the plasticizer product can in turn have negative effects on properties like the elastic recovery.
Increasing the plasticizer content lowers the crosslinking density of the cured formulation and therefore tends to shift the visco-elastic properties to the more viscous side. Since a Class 25 LM low-modulus sealant according to ISO 11600 is also required to display a minimum of 70 % of elastic recovery, a formulation highly loaded in plasticizer is unlikely to fill this requirement.
The formulation of low modulus sealants requires on the one hand a polymer that forms an excellently cross-linked network for high recovery, but on the other hand a lower density of cross-linking points for high elongation at the same time.
Furthermore, it is absolutely important to have acceptable skin formation time to ensure fast processing and at the same time dry and non-tacky surfaces to avoid dirt pick up. The ability to formulate products with high stability against climate changes and UV light and at an attractive cost-performance-ratio by allowing the addition of higher filler contents (up to 60%) is completing the picture of requested product features.
The products described here are needed for low modulus construction, transport, or assembly applications. All these features can be covered using Polymer ST or TEGOPAC®.
Suitable products for applications in low modulus sealants can be found in the product listing.
- Polymer ST 48
Polymer ST 48 is especially recommended for the application as sealant for interior or exterior joints, e.g. expansion or connection joints, inte-rior joints for dry walling, joints at staircases.
- TEGOPAC® Seal 100
TEGOPAC® Seal 100 is a moisture curing silane-modified polymer recommended for low modulus sealant formulations which are used in construction applications (e.g. for façades, expansion joints, etc. ) or for indoor applications. TEGOPAC® Seal 100 is also recommended for use in sealant and adhesive formulations where vibration and sound dampening is an issue.