Abstract
Dry-rubbing tests on several dyes have been carried out and the effect of soaping on the rubfastness has been investigated from the kinetic viewpoint.
The removal process of dyes can be treated as a reversible reaction of first order. The amount of dye (x) removed from dyed fabric to white cloth after t times of rubbings can be expressed as
where A, k1, k-1, K and F are initial dye content on dyed fabric, the rate constant of transfer of dye from dyed fabric to white cloth, the rate constant of reverse process of k1, equilibrium constant and a constant indicating initial condition, respectively. Values of F become small by soaping for vat or naphthol dyes and in many cases they become zero within an error range. The effects of soaping on the values of x are represented by the kinetic properties. From these kinetic considerations, it has been concluded that soaping effect on the rub-fastness for vat and naphthol dyes is different from that for reactive dyes.
Linear relations have been obtained between _??_nK and the reciprocal of weights (1/W) on the white cloth. The slopes of the straight lines for all of the dyes are roughly equal and they are invariant by soaping.
Relations between _??_nk1 and 1/W are roughly linear and the slopes of the straight lines for vat and naphthol dyes tend to become large by soaping.
