IMPROVEMENT OF DYEING PROPERTIES AT PRODUCTION OF PET YARNS BY ADDITION OF PBT(1)

Abstract: Polyethylene terephthalate (PET) plus an addition of up to 30% of polybutylene terephthalate (PBT) have been processed to yarn for textile applications close to industrial production conditions. Thus, applied spinning speeds were within the range of up-to-date's production speeds and even above. Due to increasingly higher spinning speeds mechanical properties of these yarns exhibit an increase in tenacity while elongation is reduced. This behavior is caused by an induced crystallization effect of PBT on the PET matrix. As a result of higher crystallinity dye up-take is somewhat reduced. As, however, by the addition of PBT the accessibility of the fiber by the dyestuff is facilitated the dye up-take increases up to fourfold to fivefold already at low PBT concentrations. Furthermore it could be demonstrated that for the dyed textiles that in spite of the high dye up-take of the PBT containing yarns their fastness properties will not drop.

Keywords: blend yarns, dyeability, fastness properties

1. Apparel fabrics of polyester fibers have recently especially in the area of high-quality products for the Aktivsport- and the leisure sector with its increased demands in terms of functionality gained enormous importance. In addition to the function which i.a. by the construction (fleece, microfiber) is determined, textiles have especially nowadays a Signaling effect, with the wearer, not only in terms of increased safety in traffic, on would like to draw attention to themselves. This effect is mainly influenced by fashionable color reaches the textile. Here, however, the standard polyethylene terephthalate (PET) has certain Disadvantages since sufficient color depths in the conventional dispersion dyeing only under HT conditions (125-130 ° C) can be achieved. The finer diameter at microfibers has an additional negative , because with decreasing filament diameter increases, the light scattering, resulting in a lighter appearance of the dyed material. To improve the dyeability, i.e. at the boiling temperature allow, can the PET by additives. eg Polybutylene terephthalate (PBT) – modified to become. Problematic but the fastness may prove as an easier diffusion of the dye into the fiber usually with an equally easy operation in the reverse Direction is associated. This issue will be discussed here in some practical approaches



Writen by R.Gutmann ICF,Institut Fur Chemiefasern der Deutschen Institute Fur Textil-und Faserforschung Stuttgart