Reactive thinner

Reactive thinners are substances that reduce the viscosity of a lacquer for processing and become part of the lacquer through copolymerization when the lacquer is subsequently hardened .

Styrene

Structure of an epoxy

Acrylic group

Thinners are added to a paint to adjust the rheology ; in particular, they serve to reduce the viscosity. In thermally curing paints , volatile substances are added that evaporate from the paint when it dries. Such thinners should not be used with radiation-curing lacquers (e.g. UV lacquers ). The addition of reactive thinners facilitates the processing of the paint, enables the addition of more fillers and improves the wetting behavior on the substrate . If volatile thinners are replaced by the addition of reactive thinners, this can improve flammability , smell , skin irritation and environmental compatibility (through lower or no VOC emissions).

Choice of reactive thinner

Since reactive thinners are incorporated into the paint and remain in it, they not only affect the viscosity of the uncured paint, but also its physical properties after curing. The choice of reactive diluent therefore has an impact on:

the adhesion of the paint to the substrate
the compatibility with the binder
the flexibility of the cured layer
the volatility
and environmental sustainability .

Low-viscosity, mono-, bi- or polyfunctional monomers or oligomers are used as reactive diluents . Usually different monomers are combined so that one monomer can compensate for the negative properties of another monomer. Although monofunctional monomers have a low viscosity, they are quite volatile and tend to develop odors. With an increasing number of functional groups on the monomers used, the volatility decreases; on the other hand, the viscosity and the crosslinking of the finished paint increase.

Styrene , epoxides and acrylates are often used as reactive thinners .

Individual evidence

↑ Bodo Müller, Walter Rath: Formulation of adhesives and sealants - the competent textbook for study and practice . 2nd Edition. Vincentz Network, Hannover 2009, ISBN 978-3-86630-862-6 , p. 149–150 ( limited preview in Google Book search).
↑ Reinhold Schwalm: UV Coatings . Elsevier, Amsterdam 2007, ISBN 978-0-444-52979-4 , pp. 112–114 ( limited preview in Google Book search).
↑ ^a ^b Stefan Pieke: Experimental studies on the efficient crosslinking of surface coatings with UV radiation . KIT Scientific Publishing 2010, Karlsruhe 2010, ISBN 978-3-86644-452-2 , p. 12 ( freely available online ).

[Müller-1] Bodo Müller, Walter Rath: Formulation of adhesives and sealants - the competent textbook for study and practice . 2nd Edition. Vincentz Network, Hannover 2009, ISBN 978-3-86630-862-6 , p. 149–150 ( limited preview in Google Book search).

[Schwalm-2] Reinhold Schwalm: UV Coatings . Elsevier, Amsterdam 2007, ISBN 978-0-444-52979-4 , pp. 112–114 ( limited preview in Google Book search).

[Pieke-3] Stefan Pieke: Experimental studies on the efficient crosslinking of surface coatings with UV radiation . KIT Scientific Publishing 2010, Karlsruhe 2010, ISBN 978-3-86644-452-2 , p. 12 ( freely available online ).