Quantification of microcapsules deposited in cotton fabrics before and after abrasion using fluorescence microscopy

Perfume microcapsules for laundry applications are extensively used in home and consumer care products. Capsules have to bind into the fabric during washing and survive the rinsing and drying steps until the desired moment of rupture, usually when in contact with the skin. In order to assess the performance of the microcapsules in the different steps, quantification methods are required. It is reported here the first methodology, using fluorescence microscopy, whereby the number and size of fluorescent microcapsules is individually determined in large fabric areas using image analysis. The performance of fluorescent melamine-formaldehyde perfume microcapsules of two different sizes under abrasion is studied using smooth and rough surfaces, under dry and wet conditions. Survival profiles are obtained with the number of abrasion passes, allowing for characterizing the performance of microcapsules under different conditions. In addition to quantification, fluorescence and optical microscopy allow for identifying where are the capsules deposited in the fabric, as well as which are the safest zones that allow microcapsules to survive extensive abrasion.