Dissertation
Dissertation > Industrial Technology > Light industry,handicrafts > Textile industry,dyeing and finishing industry > Dyeing and finishing industry > Dyeing > Dyeing of the fiber and its products

Accelerants of PLA Fiber Dyed with Disperse Dyes and Application Study

Author DangXiaoZuo
Tutor ZhengJinHuan
School Zhejiang University of Technology
Course Textile Chemistry and Dyeing and Finishing Engineering
Keywords PLA fiber disperse dye surfactant n-amyl acetate ultraviolet absorbent
CLC TS193.8
Type Master's thesis
Year 2011
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Synthetic fibre such as polyester has been rapid development since its inception, but the basic material is oil, and the over exploitation cause energy exhausted and seriously damagement on the ecological environment. At present, the harmonious development between economic construction and environmental protection are advocated, so research and development of biodegradable material become increasingly urgent. Poly(lactic acid) (PLA) is derived from 100% annually renewable sources such as corn and sugar beet, and it is a kind of synthetic fibers with good performances, which has bring new development space for textile and new challenges for textile dyeing and finishing. PLA fiber is most commonly dyed with disperse dyes due to its hydrophobic structure, but the relatively low dye up-take and poor color fastness cause the waste of disperse dyes, increase the burden on sewage disposal, and then limit its application extension in the textile industry. At present, many methods have been studied to solve the problem of low dye up-take of PLA fiber, such as surface modification, application of ultrasonic dyeing and plasticizer added in the dye bath.However, there are still some problems on the above mentioned methods.This paper is started from the different kinds of surfactants on the effect of dye uptake of PLA fiber dyed with disperse dyes, and selected two kinds of more effective surfactants to remix with a kind of plasticizer to research for plasticizing and solubilizing system, combined with the optimization of dyeing process to improve the dyeing property of PLA fiber comprehensively. In addition, apply ultraviolet absorbent added in the dye bath to improve the color fastness to light of PLA dyed fabric, which is beneficial to the healthy development of PLA fiber.First, the dye up-take and color depth in the presence of two cationic Gemini surfactants (D821 and D1021) are significantly larger than those of the other surfactants, and no effect on the color consistency. Further study find that both D821 and D1021 have abilities to improve the solubility of disperse dyes and have capacities of stronger adsorption on PLA fiber, which are beneficial to shift more disperse dyes to PLA fiber from the dye bath. But more disperse dyes are only adsorbed on the surface of the PLA fiber cause the higher degree of irregularity of the dyed fabric, and comparatively lower color fastness is due to less dyestuff transferred into the interior of the fiber. N-amyl acetate as a kind of organic compound could enter into the interior of the PLA fiber, play the role of plasticizer to transfer the dyestuff adsorbed on the surface to the interior.So the plasticizing and solubizing system could be used to research the accelerating agents to solve the problems of dyeing properties of PLA fiber.Emulsification technology is needed in the dyeing process due to n-amyl acetate is insoluble in water. And the two kinds of surfactant D821 and D1021 were found could play the role of emulsifier during the choice of the emulsifying agent. So the preparation of the two accelerants are as follow: D821 0.5g/L(D1021 0.3g/L), n-amyl acetate 6mL/L, appropriate water was added according to the proportion, emulsified 10min at the speed of 10000r/min using a emulsifying machine to ensure a stable system with milk white appearance.The dye up-takes of six kinds of disperse dyes on PLA fibers when the two accelerating agents added in the dye bath achieve more than 90%. Color depths are almost increased to two to three times when compared with the samples of blank. What’s more, the dyed fabrics are uniform coloration and soft handle.But the levels of fastness to washing is slightly decreased.When the dyeing time increased to 50min from 40min, the color fastness could attained to more than 4 level.Second, through the study of fiber diameter and XRD analysis, the fiber diameter and sectional area are increased when the two kinds of accelerating agents added in the dyebath, but little effect on the crystalinity degree of the PLA fiber, which is beneficial to maintain the performance of the fiber. Three different structure of disperse dyes were used to the kinetics study of the two kinds of accelerating agents for PLA fiber dyed with disperse dyes.The results show that the diffusion coefficients, dyeing rate constants and equilibrium adsorption amount are improved significantly compared with the blank, which means the two acclerants have general applicability among PLA fiber dyed with different disperse dyes.Last, two kinds of ultraviolet absorbent were used to study the improvement of color fastness to light for PLA fiber dyed with disperse dyes(ultraviolet absorbent 1 and ultraviolet absorbent 2).The results show that the uptake of ultraviolet absorbent and disperse dye are all increased to 90% or so when the two kinds of accelerating agents added in the dyebath. The high uprate of ultraviolet absorbent means the lower average UV transmittance and higher UPF value, and the PLA fabric could attain the standard of“Anti-UV product”according to GB. In the terms of color fastness to light, slightly improved for the color difference of PLA dyed fabrics decreased. And ultraviolet absorbent 2 is better to improve the color fastness to light of the PLA dyed fabric.

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