Nonsolvent polyurethane prepolymers for high-performance adhesives
Finding adhesive raw materials that have processing and application advantages combined with lower environmental impact is a challenge. Using its extensive knowledge of polyurethane chemistry, Covestro has developed 100 percent solids prepolymers that meet this need, even for difficult adhesive applications.
Our polyurethane prepolymers are prepared by reacting polyols with an excess of polyisocyanate. This results in stable polyurethanes that are readily incorporated into adhesive formulations.
By varying the polyol (polyether, polyester) and polyisocyanate (aliphatic, aromatic) components and their molar ratios, we produce prepolymers with varying processing, application and physical properties.
Our 100 percent solids polyurethane prepolymers offer several advantages:
- Longer pot life
- Low residual monomer content for label-free adhesives
- More favorable balance of components
- Formulated without solvents
Desmodur® E prepolymers have free isocyanate groups that react via moisture curing with ambient humidity for high-performance. These one-component (1K) adhesives are useful in many different applications. Fine-tuning of adhesive properties is also achieved through the formulation of two-component (2K) systems with short-chain polyols or polyamines.
Desmocap® prepolymers have blocked isocyanate groups that are removed upon heating. They can be blended with polyol components to formulate 1K flexible sealants with 2K performance.
Desmoseal® S silane-terminated prepolymers combine the benefits of a polyurethane backbone with a silane-based curing mechanism. They are used in sealants and adhesives for construction, transportation and other industrial applications. Desmoseal® M polyurethane prepolymers are suitable for moisture-curing 1K sealants and to elastify harder systems.