Influence of the stilbene series fluorescent brightening agent (FBA) in the built detergents on the color of dyed materials were investigated by repeating of washing.
The color differences were examined spectrophotometrically,
L, a, b, and
ΔE values of CIE series were computed accordingly.
Test textile samples used were both dyed cotton and polyester/cotton mixed broad cloths of various pale colors (blue, green, yellow, pink, and violet) respectively.
Test detergents used were JIS-standard formulations of detergents both with and without FBA built.
The washing conditions were : detergent concentration 0.15 % (soln.), washing temperatures 25 and 40°C, washing time 10 min/cycle.
The results obtained were summarized as follows :
1) As the washing cycle increase, the peak of reflection curves (430-450 nm) rise gradually due to the adsorption of FBA in detergent solutions and these phenomena appear more remarkably on pale color, and on cotton than on P/C mixed, and at the washing temperature of 40 °C than 25°C.
2) At the same time, in the CIE chromaticity diagram
a and -
b values increase, that is the color shifts occur toward blue to violet. These changes are remarkable on paler color cloths, and large color differences
ΔE were also observed.
From these results built detergents without FBA are more recommended for washing of dyed cotton and polyester/cotton mixed cloths of pale color.
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