Rokryl SU25 is an anionic aqueous acrylic dispersion used as a binding agent in leather coating processes in the tanning industry. The product is an acrylic copolymer obtained by emulsion polymerization with the use of anionic-ionic dispersion system.
The product has the form of opalescent liquid of white colour. It dissolves well in water and is miscible with auxiliary agents used in the preparation of tightening formulations in non-bath processes. It is also miscible with all additives used in the finishing processes.
Rokryl SU25 shows no tendency to delaminate and does not increase its viscosity during storage. However, it is sensitive to low temperatures – it freezes at temperatures below 0 ° C, and after thawing, it coalesces (increases the size of the latex particles). This reduces the ability of the polymer to penetrate the surface of the leather and causes a loss of functional properties. Repeated freezing and thawing leads to irreversible coagulation.
Rokryl SU25 is an impregnating, soft primer resin. Through its use, the grain is strengthened, without hardening the leather and reducing the adhesion of the subsequent coating layer. It is perfect for tightening the leather grain, as it is a polymer with adequate softness and an appropriate particle size, allowing the polymer to settle in the grain layer of the skin.
Rokryl SU25 is usually used in combination with Rokpen SU25 as a regulator of its penetration depth, while Roksol STE is used as a preparation against degreasing of the skin surface.