Content - MOLTOPREN® S

ISL: Moltopren® S

Reactive dyes for polyether and polyester based polyurethane flexible foams

Technology description

An appealing and efficient coloristic design of polyurethane parts and foams is an important marketing tool and generates significant added value.

In contrast to conventional pigment pastes, no application restrictions apply to the products of the Moltopren® S series which were developed based on reactive dyes. They can be used to produce polyether-based and polyester-based flexible polyurethane slabstock foams with high quality and safety requirements without any problems.

The requirements of the Bedarfsgegenständeverordnung [German consumer goods ordinance] for BLS/skin contact, the Toy Safety Directive (standard EN 71-3 / except for sections EN 71-5, EN 71-7, EN 71-9) and the provisions of the Oeko-Tex Directive are complied with. A pre-registration according to REACH is available.

In contrast to commonly used polyol-based pigment pastes, Moltopren® S reactive dyes are integrated in the polyurethane matrix via hydroxyl functional groups. Once integrated, they can no longer migrate, bleed or be extracted by various media.

Under the application conditions which are common in slabstock foam, the reactive dyes are completely soluble and do not cause any foam defects which often occur when pigment pastes with high pigment content or in higher dosages are used (e. g. pinholes, foam cracks, delays in rising time and curing time, reduced height of rising, shrinkage, etc.).

In liquid CO2 foaming (Novaflex process) which is used to produce foams with low <s>bulk</s> densities, pigment pastes usually cause problems due to their solids content. With Moltopren® S reactive dyes, however, it is easily possible to colour foams produced with this technology as well. If these dyes are used, the foams have a homogenous structure which means that the product quality is enhanced.

Thanks to their very high colour strengths, excellent brilliance and low viscosity settings, Moltopren® S reactive dyes provide important application benefits and are therefore highly cost-efficient compared to commonly used pigment pastes.

With the available primary colours red, yellow and blue, all important basic colours and many secondary colours can be created in slabstock foams.

We are continuously working on expanding the product range.



Common colouring intensities are 0.1 to 3.0% (referring to the polyol component) depending on the application.

Moltopren® S reactive dyes can be combined or mixed with Moltopren® pigment pastes.

The reactive dyes can be processed using common dosing units.



  • High cost efficiency compared to pigment pastes and commercially available products
  • Foams with very high colour strengths and excellent brilliance can be produced
  • No application restrictions for the use in flexible polyether and polyester polyurethane foam
  • Compliant with Bedarfsgegenständeverordnung, Toy Safety Directive, Oeko-Tex Directive, REACH (pre-registration)
  • Complete integration in the polyurethane matrix > no migration, no bleeding, etc.
  • No foam defects (pinholes, cracks, shrinkage, etc.) even with higher colouring intensities
  • Suitable for liquid CO2 foaming (Novaflex)


Individual advice

Our colours and lacquers can be used in versatile applications. We are at your disposal with an individual advice for your special requirement.

We are looking forward to your contact!