Evaluation of the effects of DCOIT biocide on a liquid Ca/Zn stabiliser for PVC flooring, optimization of the technology

In this scientific work the interaction between the DCOIT fungicide and a liquid Ca/Zn stabiliser for PVC flooring has been evaluated. In particular the liquid stabiliser underwent yellowing issues when it came in contact with the fungicide preventing the material from its transparency. Through spectrophotometric and colorimetric tests it was clear that the main responsible of the yellowing was the phosphite, an important component of the Ca/Zn stabiliser, which chemically reacted with the biocide leading to the breakage of its isothiazolynic ring. An innovative work on the liquid stabiliser was performed in order to find out a composition which could keep together the DCOIT and the phosphite with no problems of yellowing to the stabiliser. 3 alternative phosphites were tested but all three gave to the top coat formulation an acceptable yellowing (some more some less) for PVC flooring applications. For this reason the composition of the Ca/Zn stabiliser was modified in particular it was modified the soap regulating the metal ratio and the phosphite was eliminated in order to avoid the reaction with the fungicide. In parallel innovative Ba/Zn stabilisers were prepared, those with a high level of Ba and low level of phosphite gave good results in terms of ageing tests and static thermostability tests which were used in order to simulate the integrity of the compositions in different real conditions for example the carpet covering on the PVC floor. All the chemical analysis and probes on the stabilisers and their optimized formulations were performed in the R&D laboratory of Reagens S.P.A.