Influences of pigment and linear density on spun-dyed polyester staple fiber and yarn
Objective The large-scale application of spun-dyed fiber corresponds to multi-spes and differentiated fiber production.However,a long transition cycle when changing the fiber color type or pigment content generates a large amount of transition material or waste in this process due to the generally large capacity of the device.Therefore,it is necessary to understand the influences of pigment type,content,and fiber linear density on the color of spun-dyed fibers,as well as the color variation from fiber to yarn,so as to guide more effectively the development and application of spun-dyed staple fibers.Method The influences of pigment content(0.3%,0.9%,and 1.5%)and fiber linear density(1.56,2.78,3.89 dtex and 6.11 dtex)on the chromaticity values of semi-dull spun-dyed polyester staple fibers red,yellow,and blue were systematically investigated.In parallel,the variation of chromaticity values from fiber to yarn(linear density of 20 tex,twist factor of 300)was examined and compared with specific specifications of semi-dull dyed staple fibers and bright spun-dyed staple fibers.Results The results showed that the variation of pigment content significantly affected the chromaticity values of the semi-dull fibers,especially from light-color fiber to medium-color fiber,which is twice as much as between medium-color fiber and dark-color fiber.The chromatic aberration ΔECMC(2 ∶ 1)for yellow fibers was 21.8 and 8.4,respectively,which is about three times higher than that for red and blue,mainly because of the contribution of the hue difference ΔH.The influence of fiber linear density variation on ΔECMC(2 ∶ 1)was not significant,and the higher the linear density,the weaker the effect.Similarly,the ΔECMC(2 ∶ 1)of yellow was more obvious than the other two colors.When producing products such as yellow,especially fine denier fibers,adjusting the linear density required reconfirming the pigment formulation.In general,the variation of chromaticity values from semi-dull spun-dyed staple fiber to yarn was not significant,with ΔECMC(2 ∶ 1)in the range of 0.8-2.6.On contrast,the variation of chromaticity values of yellow semi-dull dyed staple fiber to yarn was large,with ΔECMC(2 ∶ 1)in the range of 3.4-3.9.On further examination,the change rate of ΔECMC(2 ∶ 1)for dyed fibers was 1.8-6.5 CMC(2 ∶ 1)/dtex,which was significantly higher than that of spun-dyed fibers.It was also evident that the ΔECMC(2 ∶ 1)of dyed fibers did not show a significant decrease in the change rate of ΔECMC(2 ∶ 1)with the increase in the linear density of the spun-dyed fibers.The variation of chromaticity values from bright spun-dyed polyester staple fibers to yarn was similar to that of semi-dull dyed staple fibers,and ΔECMC(2 ∶ 1),ΔL,ΔC,and ΔH were basically the same meaning that for specific color types,the yarn color matching experience of dyed fibers did serve as a reference.Conclusion The chromaticity values of semi-dull staple fibers vary greatly with pigment types and content ranges.When the pigment content needs to be changed significantly during the production process,the masterbatch should be reformulated.Different fiber linear density ranges have different influences on the chromaticity values of the fibers,and the normalized results suggested that the smaller the linear density,the greater the change rate of ΔECMC(2 ∶ 1).Among them,the change rate of ΔECMC(2 ∶ 1)is most obvious for yellow,which is mainly due to larger ΔH,indicating that the adjustment of linear density requires reconfirmation of the masterbatch formulation when producing products such as yellow,especially fine denier fibers.For conventional linear density of semi-dull spun-dyed fibers,the color variation from fiber to yarn is not obvious.However,when the fiber linear density is small enough,such as ultrafine fibers prepared by composite spinning,this result needs to be re-examined.Overall,the change rate of ΔECMC(2 ∶ 1)of dyed fibers is significantly higher than that of spun-dyed fibers,mainly due to the different chromophores of dyes and pigments.The color variation from fiber to yarn for the bright spun-dyed fibers is essentially the same as that for the semi-dull dyed fibers,implying that the color variation law from semi-dull dyed fibers to yarn can be utilized to guide the yarn color matching of the bright spun-dyed fibers.
polyester staple fiberspun-dyed fiberpigmentlinear densitychromaticity valueyarn color matching
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