Rheobyk-440: New liquid, polyamide-based rheological additive for aqueous systems

Rheobyk-440: New liquid, polyamide-based rheological additive for aqueous systems

Friday, 12 April, 2019

BYK’s organic rheological additives are now called Rheobyk. Under this new name a new additive has been introduced: Rheobyk-440. It is the first polyamide-based additive for aqueous systems. It is supplied in liquid form and is pre-activated:

The additive is suitable for aqueous epoxy and two-component polyurethane systems, acrylic melamine, as well as acrylic and water-based one-component polyurethane. Incompatibilities may appear when adding regular rheological additives to aqueous epoxy systems, as well as viscosity increase during storage and poor sagging resistance. Rheobyk-440 is completely compatible with modern epoxy systems, it provides increased resistance to sagging and settling without detriment to corrosion or coating adhesion to the substrate.

The additive can be incorporated into both component A and component B. The graph shows the rheological profile of an aqueous epoxy system after adding the hardener. With 0.5% active substance of Rheobyk-440 in component A, it is observed how the system does not undergo loss of viscosity.

Graph: Rheological profile of a two-component aqueous epoxy system with Rheobyk-440 and an associative thickener.

The additive should be added at post-addition and subject to moderate shear forces (6 m/s for 5 minutes), and its efficiency is independent of the pH of the system. The efficiency of Rheobyk-440 is complete 4 hours after its introduction.

Rheobyk-440 has anti-settling properties in various systems. The image shows how in a metallic topcoat based on a two-component acrylic, 0.1% of Rheobyk-440 as an active substance provides excellent anti-settling properties after 7 days at ambient temperature.

Image: Anti-settling properties of different rheological additives.

Furthermore, the additive at 1% of active substance is capable of increasing flop in an OEM metallic base coat, applied with an electrostatic gun and a layer thickness of 10 μm.

Graph: Evaluation of the pigment effect orientation (flop value) in an automotive aqueous base coat with different rheological additives and their combinations.

In summary, Rheobyk-440 provides a pseudoplastic profile to the system, affording excellent anti-sagging and anti-settling properties, as well as good aluminium orientation (improving if combined with Laponite RD). Moreover, it maintains the viscosity of the system when the hardener is added, with high compatibility and without negative effects on corrosion or adhesion.

For further information about these products, please contact our Technical Sales Advisors.

URL: www.byk.com

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