Rokpen SU25 is a speciality additive used in the tanning industry. It acts as a regulator of the penetration of anionic acrylic water dispersion (Rokryl SU25) into the surface layer of leather. The product is an aqueous dispersion of a non-ionic surfactant and organic solvent. It has the form of a clear liquid with a colour ranging from colourless to pale yellow. The product is non-flammable.
The product is characterized by high solubility in water at any ratio. It is also soluble in ethanol. Rokpen SU25 is resistant to electrolyte solutions, i.e. ammonia water, formic acid and sodium chloride.
It is miscible with the auxiliary agents used in the tightening preparations for the non-bath leather tightening process, as well as with all the additives used in the finishing process. Rokpen SU25 has a solidification point at -10°C. Below this temperature, it freezes, and after thawing and mixing it returns to its original state without losing its functional properties.
The product ensures reduction of surface tension and quick wetting of the leather surface, which facilitates the penetration of a water-based tightening dispersion. The solvent contained in Rokpen SU25 may cause partial degreasing of the leather surface. In some cases, especially when firm leather requires large amounts of Rokpen SU25, it may cause roughness of the material. This is effectively counteracted by the addition of Roksol STE.
The grain tightening preparation based on Rokryl SU25 and Rokpen SU25, gives a foundation that strengthens the grain without hardening the leather and reducing the adhesion of the subsequent covering layer.
Leather impregnated with this unique set of products is characterized by the following features: