Nonwoven Uniformity — Measurements Using Image Analysis

Abstract

Statistical measures have been developed for quality control as well as characterization of mass distribution in fibrous substrates. The mass distribution in 2D space has been measured by imaging the substrate. The intensity distribution of reflected/transmitted light has been used as a representative of the mass distribution. Spatial mass uniformity has been measured in terms of a standardized index of dispersion and mass anisotropy ratio that are reasonably independent of fiber mass density. The dispersion index is standardized between the limits of −1 and +1, with −1 representing uniform distribution and +1 representing aggregated distribution. Furthermore, the standardized values have been combined with the qualitative grades to categorize and differentiate uniform patterns. Standardized index of dispersion and mass anisotropy ratio have been evaluated for a wide range of non-woven webs and adhesive lay down patterns.