Source: New Cloth Market
Abstract
Many attempts to use water dyeing polypropylene (PP) fibers have not resolved the undyeability of the fibers very successfully. Because of the success of dyeing polyester withdisperser dyes in supercritical fluid many attempts to apply this technique to dyeing PP fibers have been made. This paper discusses the advantages andfeasibility of dyeing PP in supercritical fluid instead of water. Approaches of dyeing PP fibers in supercritical fluid and the dyes used in supercriticalfluids are also reviewed.
Keywords:
Introduction
The worldwide consumption of polyolefin fibers, mainly PP has grown rapidly in the polymer market since 1980s. The growing demand for PP fibers can be explained by their several intrinsic, advantageous properties, namely easy processability, low specific gravity, almost zero water adsorption, good chemical resistance, good antistatic character as well as wide availability and low cost.
PP fiber has a non-polar, aliphatic structure with its high crystallinity and highstereo-regularity which are responsible for the good physical properties of thematerial. PP fibers are difficult to dye since their structure does not contain dye sites to which certain kinds of dyes will bind. To improve the dyeability of PP fibers, the primary mission is to investigate the solvents capable of penetrating the PP structure so as to carry a dyestuff into the penetrated fibers. Since conventional dyeing medium---water does not resolve this successfully.
Fiber modifications without deterioration of the positive characteristics of PPfibers have been tried to make conventional water-dyeing possible, but most of them have not been successful till now. The application of new polymeradditives changed the positive characteristics of PP fibers. The high cost of blending Pp fibers with other fibers made the technology unsuitable for commercial use.
Originally published in New Cloth Market, March-2011
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