Effect of different filters on the extraction of norbixin from Bixa orellana for synthetic fiber dyeing and development of a post-dyeing process for removal of the unfixed dye

The aim of this study was to compare the efficiency of three types of filters for the extraction of the annatto dye from Bixa orellana for polyester dyeing. In addition, post-dyeing washing processes were proposed to improve the wash and rubbing fastness. In the extraction procedure the paper filter presented the highest yield (13.3%), followed by the polypropylene (11.4%), but there was no significant difference in the results for the exhaustion percentage (average of 87.4%) and K/S values (1.68 to 2.24). Results showed the polypropylene filter was the most suitable and can be reused. The post-dyeing washing processes with detergent improved the fastness increasing the color transfer score from 1.5 (large change) to 3 (small change). An acceptable color difference between the dyed fabric samples before and after washing was observed. Results indicate that the post-dyeing washing process improves the quality of dyed fabrics to levels acceptable for industrial application.

Review on Intermolecular Forces between Dyes Used for Polyester Dyeing and Polyester Fiber

Polyester fiber is a manufactured fiber composed of synthetic linear macromolecules in the chain at least 85% by mass of an ester of diol and benzene-1, 4-dicarboxylic acid (terephthalic acid). Fibers of the most common polyester, poly(ethylene terephthalate) (PET or PET), are generally made from either terephthalic acid or dimethyl terephthalate together with ethylene glycol. Dyeing of polyester fabric with disperse dyes, polyester requires the use of dispersing agents. The chemical characteristics and general application conditions of disperse dyes are characterized by the absence of solubilizing groups and low molecular weight. Dye particles have a size ranging from 0.5 to 2.0 microns, generally contain –NH2, substituted –NH2, or –OH groups in the structure, and get attached with the fiber through H-bond and van der Waals force. Dyes are retained by the fiber by physical forces. Fastness properties are very high in polyester except in certain cases. The dye-fiber (PET) affinity is the result of different types of interactions, such as hydrogen bonds, dipole-dipole interactions, and van der Waals forces.

Influence of dispersing agents on adsorption and desorption rate of a disperse dye on polyester

Dispersing agents play important roles in polyester dyeing with disperse dyes. The purpose of this work is to determine the influence of dispersing agents on the adsorption and desorption rate of polyester dyeing with CI Disperse Blue 284. Polyester fabric was dyed at HTHP method using two types of dispersing agents at different concentrations. The performances studied were the changes in dye transfer rate, K/S values of the dyed samples and dye bath concentration. The rate of adsorption and desorption of disperse dyes were affected significantly not only by the type but also the concentration of dispersing agents.

Modification of Polyester Textiles for Easier Dyeing with Disperse Dyes

Modification of polyester fibers for more economical dyeing at lower temperatures without a carrier are considered in this study. Polyester dyeing is carried out industrially under rigorous conditions at high temperatures and under increased air pressure, and are treated with various solvents (primary alcohols) to make the fibers more permeable. As a result, the sorption properties, as well as the disperse dye dyeing ability, are improved. Dyeing of a modified polyester fabric at lower temperatures yielded better results than the standard dyeing of the unmodified polyester under the same conditions. The effects of fiber modification were analyzed through water absorption properties, wetting, swelling, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) methods, and the degree of dyeing of the fabric was evaluated using CIELab parameters.

Thermodynamic and kinetic parameters of polyester dyeing with Disperse Blue 56 using bio-based auxiliaries and co-solvent microemulsion

The aim of the study was to dye polyester fabric with a low molecular weight anthraquinone type disperse dye (C.I. Disperse Blue 56), with n-butylacetate as co-solvent in the microemulsion system and the presence of two bio-based auxiliaries (ortho-vanillin and coumarin), at temperatures lower than 100℃. In order to investigate the influence of temperature and auxiliaries on the kinetic dyeing process, the energy of the activation was determined by the kinetic rates constants. The activated entropy values were obtained by the theory of absolute rates of dyeing and diffusion of the activated state of the dye for the disorder state of the dyeing system. Higher activated energies were found, as well as higher activated entropy, meaning higher dye absorption, for polyester samples dyed with ortho-vanillin/n-butylacetate compared with polyester samples dyed with coumarin/n-butylacetate. Color strength values of the polyester fabric dyed using the proposed microemulsion dyeing system at low temperature (95℃) were similar to polyester fabric dyed with a conventional dyeing system at high temperature (135℃). Regarding color fastness to washing and ironing, it was found that the use of the auxiliaries did not significantly modify the fastness values of the dyed samples.