Adhesion is one of the most critical properties for any coating, ink, adhesive, or sealant formulation. An adhesion promoter additive is often required to improve adhesion. Adhesion promoters will typically interact with the substrate and functional groups within the formulation’s polymer network to form a chemical bridge between the formulation and the surface it is being applied to.
Lupasol® Adhesion Promoters
BASF Lupasol® is a family of branched polethyleneimine polymers with a very high cationic charge density. Due to this charge density, Lupasol® polymers adsorb strongly onto negatively charged surfaces, such as paper, metals, and plastics. Lupasol® works well as an adhesion promoter with plastic substrates like polyolefins, polyesters, nylons, metals, and halogenated polymers, such as PVC and PVDC. Therefore, Lupasol® is often used as an adhesion promoter or primer in adhesive, printing ink, and coating formulations applied to a variety of surfaces.
Adhesives
Lupasol® adhesion promoters are commonly used in polyvinyl alcohol, polyvinyl butyral, polyvinyl acetate, and styrene-based adhesives to improve adhesion to metal, plastic, and cellulose-based substrates. In addition, low–molecular weight grades of Lupasol® can be used to cross-link polymers in an adhesive to improve cohesive strength dramatically. Typical Lupasol® addition rates in adhesive formulations range from 0.1 to 1.0%.
Adding even a small amount of low–molecular weight Lupasol® can significantly improve the cohesive strength of an adhesive by cross-linking polymers in the formulation. As shown below, the cohesive strength of an acrylic pressure-sensitive adhesive was tested with varying levels of Lupasol® G 20.
Improvement in Cohesive Strength with Lupasol® G 20
Paints & Coatings
In emulsion-based paint formulations, adding a small amount (i.e., 0.1%) of a low–molecular weight Lupasol® polymer can significantly improve adhesion to wet surfaces. This becomes especially important in kitchen and bathroom painting applications.
The increase in wet adhesion is demonstrated by the testing data below. In this test, a commercially available vinyl acrylic latex paint was modified with varying levels of Lupasol® G 35. The paint was then applied to a glossy alkyd substrate, and wet adhesion was tested according to ASTM D3356.
Improvement in Wet Adhesion with Lupasol® G 35
Printing Inks
Lupasol® is commonly used as an adhesion promoter in printing inks for laminated films. It is particularly effective for sandwich-printed laminated films where ink adhesion is needed between two different types of film. It is important to note that Lupasol® is strongly basic and should only be used with binders and pigments that are stable in alkaline environments.
BASF Lupasol® is a class of branched polyethyleneimine polymers with an extremely high cationic charge density, allowing Lupasol® polyethylenimines to bond strongly to negatively charged surfaces and functional groups on polymers. This ability makes Lupasol® a highly effective adhesion promoter additive and primer recommended for pressure-sensitive adhesive, latex paint, and printing ink formulations to improve adhesive and cohesive strength.
Lupasol® is available in different molecular weights and solids content. For a complete list of Lupasol® polymers, click here. You can also click below to discuss your application with us, and we would be happy to recommend the right Lupasol® adhesion promoter for you.
