Influence of Suessen and Superba Heat Setting on Optical Streak Intensity in Finished Nylon Carpets

Abstract

Texturing conditions were systematically adjusted in a factorial experiment to create twenty-four yarn items that varied in their respective bulk levels. Following a heatsetting treatment by one of three methods (one dry, the Suessen at a tunnel temperature of 200°C, and two wet, the Superba at tunnel temperatures of 129.4°C and 137.8°C), each item was implanted as a triple tuftline into two carpet backgrounds that also differed in their respective levels of bulk. Forty-eight such implanted streaks from each heat-setting method—144 streaks in all—were then rated by shade and intensity and contrasted by method of heat setting. The relative intensity of the low-bulk dark streaks was worst for the Suessen-set treatment and best for those Superba-set at the higher temperature. Suessen heat setting enabled smaller bulk differences to be seen in the carpet.Streaks, predominately dark streaks, still constitute a significant quality problem in the manufacture of tufted Saxony carpets today, and their prevention has long been a cause for concern in the carpet manufacturing industry as well as for the fiber producers ( Figure 1 ) . LeGault [ 6, 7 discussed the wide variety of possible causes, while Miller and Southern [ 8 ] recently showed that bulk-related differences induced at texturing can indeed survive the heat-setting treatment and produce streaks in the finished carpet. Unlike streaks caused by tuftlines with dye-on-fiber differences-true &dquo;dye streaks&dquo; as discussed by Baxley and Miller [I]-the FIGURE 1. Triple implant, low-bulk, optical carpet streaks in Saxony cut-pile BCF carpet. Bottom streak disappears as pile is brushed to show the with-pile view. , so-called bulk-related &dquo;optical&dquo; streak produces its effect through a contrast in surface light scattering properties of the low bulk versus high bulk tuftlines: the filament configuration of the top few millimeters at the carpet's surface is a function of the fiber bulk level.The optical streak's trademark-certainly when it is bulk related-is its shade dependence on the direction from which the streak is viewed: for example, a dark optical streak viewed into the carpet's pile will quite often appear light when viewed from the opposite &dquo;with-pile&dquo; direction. In Figure 1. for example, the carpet is viewed against the pile, and the low-bulk implanted tuftlines appear dark, but when one of the streaks is brushed so that the view is with the pile-as in the top portion of the lower streak-the streak disappears. The experiments I report here document the interaction between preheat-setting bulk differences and the heat-setting environment itself..

Goniophotometric Assessment of Bulk-Related "Optical" Carpet Streaks in Finished Nylon Carpets

“…When the light's impingement angle is close to perpendicular to the reflecting surface, absorption is preferred, but as it becomes more glancing, a greater percentage is reflected according to Fresnel's law [ 3 ] . The carpet's light-scattering behavior accounts for its observed color, luster, and sparkle [ 1,5,6,20 ] , its change in shade with wear [ 7,8,16,21,23 ] , and its general degree of streakiness [ 12,13,14,15 ] .…”

“…Most BCF is heat set in a Superba chamber-the &dquo;wet&dquo; heat-setting methodfor better streak uniformity. While these staple items were only heat set in a Suessen chamber held at 200°C, the BCF yarns were heat set three ways: in a Suessen at 200'°C and in a Superba at both 129 and 138°C [ 14 ] .…”

“…, Bulk-related streaks are more accurately assessed from a combination of the against-pile and with-pile gradings. In past work [ 14,15 ], we have produced good correlations between the process and product variables by combining the two ratings into an implant contrast grade (ICG), defined as Implant contrast grade We calculated grading limits for the single view ratings for the icG grades by combining the against-pile single-grade criteria with the with-pile grade calculated from Equation 2; the regression model for the data is . plotted in Figure 2.…”

“…Further, Miller [14] has recently shown that a streak's severity can be modified by heatsetting conditions. In this study, we extend our earlier work to the staple process and again present relationships between bulk-related optical streaks and several new measures of bulk.…”

“…In some instances, heat-set yarn is warehoused until needed, and heat-set cones can easily be mixed from different yam lots or different heat-setting tunnels, thus producing carpet tuftlines with variable levels of bulk. The products from different Suessens-a dry, heat-set method with six tunnels [2,4 ] -and from different Superbas-a wet, heat-set method with a single tunnel [14,15 ]-are usually segregated but not monitored under any bulk-control criteria. Any condition that results in extreme tuftline-to-tuftline bulk differences can produce rogue tuftlines with bulk variation large enough to scatter light differently from the background surface.…”