In addition, as PP accounts for 63% of the 89.5% synthetic fibre content of global nonwoven production [12] and, since it is well known [17,18] that isotactic PP is undyeable owing to its non-polar, aliphatic structure, high crystallinity and high stereo-regularity, which limits the accessibility of dye molecules, the coloration of
nonwovens is commonly undertaken using mass coloration or by employing pigments that are dispersed in the binders that are used to stabilise the nonwoven web [19]. Whilst dyes can also be used in admixture with binders, this particular approach is more suited to nonwovens made from a single fibre type [5]