Objective Hand Measurement of Nonwoven Fabrics Used for the Top Sheets of Disposable Diapers

Abstract

This study investigates the objective hand evaluation of top sheet materials used for disposable diapers based on their mechanical and surface properties. Previous experience has shown that a system for men's suiting is also useful for other materials, so we have used this system to assess the hand of top sheet nonwovens in terms of three primary hand values (stiffness, smoothness, and fullness). The equations for the men's suiting hand are modified such that each of the mechanical parameters substituted into these equations is normalized by using the respective mean value and standard deviation of the top sheet nonwoven population. The objective hand value of the top sheets is derived using both the men's suiting and general nonwovens equations. The subjective hand of the top sheets is assessed by students, and the mechanical and surface parameters are measured with the KES-FB system. It is clear that the hand of the top sheet nonwovens can be predicted by the equation developed for general nonwovens, for which the calculated error is within the range of the standard deviation of the subjective hand value of each product. Correlations between the hand of the disposable diapers and calculated hand of its top sheet nonwoven are also examined. The primary hand value of smoothness of the top sheets serves as a useful indicator for estimating the diaper's hand.