Research On The Effect Of Alkaline Treatment And Reactive Dye Inkjet Printing On Lyocell Fabrics

Lyocell is a solvent-based regenerated cellulose fiber,and was widely used for its excellent physical and mechanical properties.Due to the high degree of crystallization of the Lyocell fiber,and its cortex was easily fibrillated by external forces,the dye was difficult to diffuse into the fiber when applied to inkjet printing,resulting in poorer color depth of printed patterns.In this paper,the same surface modification of Lyocell fabric and cotton fabric with the same structure was used for inkjet printing to investigate the difference in inkjet printing effect between the two fabrics.The Lyocell fabric was treated with NaOH,and the contact angle and surface energy of the fabric surface before and after alkali treatment were tested.The scanning electron microscope(SEM)and X-ray diffraction(XRD)were used to characterize the surface and aggregate structure of the fabric before and after alkali treatment.Finally,the apparent color depth,sharpness and color fastness of the inkjet printing fabric were tested.The results show that when printing color patches with a 100%color fill ratio,the apparent color depth K/S value of the cyan patch printed by Lyocell fabric is reduced from 12.1 to 7.9 compared to cotton fabrics with the same structures;The apparent color depth K/S value of the red block is reduced from 7.7 to 6.6;the apparent color depth K/S value of the yellow block is reduced from 9.0 to 8.7;the apparent color depth K/S value of the black block was reduced from 8.70 to 7.90,the color depth and vividness of the Lyocell fabric inkjet printing were poor,but the printing sharpness was better.After the Lyocell fabric was piled up with 100 g/L NaOH for 6 hours,the contact angle of distilled water on the fabric surface was reduced from 130.8°to 42.9°compared with the non-alkali-treated Lyocell fabric;the crystallinity of the fabric decreased by 6.04%;The brightness value L~*of the cyan patch was reduced from 69.0to 63.7,the saturation C~*value was increased from 38.3 to 42.3,and the apparent color depth K/S value was increased by 36.2%.The study of NaOH concentration gradients under different piling times of alkali treatment showed that the apparent color depth K/S value of Lyocell fabric increased rapidly and then stabilized with increasing NaOH concentration at the same stacking time.Among them,after piled 100 g/L NaOH solution for 12 h,the apparent color depth K/S value was the highest.The K/S values of cyan,magenta,yellow and black fabrics increased by 77.9%,44.9%,41.2%and 63.3%,respectively,compared with the non-alkali-treated Lyocell fabric.However,in terms of ecological environment protection and cost saving,the alkali-treated NaOH concentration was selected to be 10 g/L and piled for 12 h.At this time,compared with the non-alkali-treated Lyocell fabric,the cyan,magenta,yellow,and black K/S value increased by 60.5%,30.7%,36.9%,48.4%respectively,color depth,sharpness and color fastness are better.This study has practical application value for improving the effect of inkjet printing on Lyocell fabrics,and provides a technical approach for further promoting the application of Lyocell in high-end clothing and home textiles.