Easy-Care Finishing Of Cotton Fabrics

Easy-care finishing of cotton fabrics as an important step in finishing processes, has been paid great attention for a long time, however, easy-care finishing for higher DP rating has been a hard task since the technology of wrinkle resistant finishing came into existence. In this research, the cotton fabrics pretreated with or without liquid ammonia （AF/LAT or BF/LAT） were finished with the ultra-low formaldehyde finishing agent of SDP1 to improve their easy care performances by the traditional pad-dry-cure process and the steaming process, respectively.For the traditional curing process, the effects of crosslinking agents and two different catalysts were investigated to decide the suitable formulation, and the easy-care finishing performances of the AF/LAT and BF/LAT fabrics were also compared. The suitable parameters of steaming process were explored by orthogonal test. The results reveal that AF/LAT fabrics gain higher whiteness and wrinkle recovery angles （WRAs）, and the fabric samples finished by the steaming process exhibit higher WRAs, retention of the tensile strength, whiteness and soft handle. Furthermore, the optimum steaming condition was decided to be 150℃, 3min and the relative humidity of 30%, and the corresponding finishing formulation is SDP1 120g/L, MgCl₂ 18g/L and CA 1.2g/L. The liquid ammonia pretreated cotton fabrics with the optimum steaming process can gain a higher DP rating of 4.1.Compared the steaming process with the traditional curing process in the two cases: with or without softening agents. When the steaming temperature was 150℃, the experimental results revealed that the fabrics’ WRAs were nearly the same with the two processes, but the strengths of the steamed fabrics are better than those finished by traditional process. When the steaming temperature was 160℃, the fabrics have similar physical and mechanical performances while the steamed fabrics exhibit better easy-care performances. The steaming process can also impart a pleasing handle and better appearance to treated fabrics.The formaldehyde release from fabrics treated by steaming method is higher than that treated by the curing method. In order to decrease the formaldehyde release, several methods were studied. Reducing the dosage of the finishing agent or increasing the amount of catalysts can decrease the formaldehyde release to certain extent, but the finishing effects were influenced. Formaldehyde release can also be decreased by adding some additives. Polyethylene glycol （PEG） can reduce the formaldehyde release without influence on the finishing effects. It can also improve the strength retention and whiteness of the treated fabrics. The proper dosage of PEG is 30g/L. Ethylene glycol （EG） is another effective additive and its proper dosage is no higer than 20g/L.The reasons for the higher formaldehyde release from the steamed fabrics were explored. The formaldehyde release from the fabric samples was determined again and again, and the WRAs of the samples before and after formaldehyde release determination were compared and explained. And the formaldehyde release from the untreated fabric was also explored. These investigation showed that the hydrolyzation of ether bonds was not the answer for the higher formaldehyde release from the steamed fabrics, but the single-end products and the formaldehyde left in the steaming chest were the main factors.Finally, the different kinds of cotton fabrics were finished and compared. When the WRAs are similar, the concentration of SDP1 used in treating the AF/LAT is 30～40g/L less than that used in treating the BF/LAT. At the same concentration of SDP1, the WRA of the AF/LAT is 20～40°higher than the BF/LAT, and the whiteness, the handle, the DP rating of the AF/LAT are better than that of the BF/LAT. The WRAs of the treated poplin and oxford fabrics can be higher than 290°. The DP rating of the poplin is slightly lower than that of the oxford by 0.1. The breaking strength of the poplin is stronger than that of the oxford, whereas the tear strength of the poplin is lower.