Surface Pretreatment Of Hemp Fabric And Inkjet Printing With Reactive Dye

Hemp textile has excellent wearing properties,such as good moisture absorption and moisture dissipation,anti-enzyme and anti-bacterial properties.However,it has low dark color performance,light color poor levelness and poor color fastness because of its low cellulose content,high content pectin and lignin to remove difficultly,as well as high crystallinity and orientation.In addition,there are few reports about inkjet printing of hemp fabric.In this paper,compared with the traditional printing pretreatment agent sodium alginate（SA）,the natural polysaccharide polymer xanthan gum（XG）and carboxymethyl guar gum（CMG）were treated on hemp fabric.At the same time,an environmental urea-free pretreatment process had been developed.By investigating the spreading phenomenon of ink drops on the treated fabric and the inkjet printing effect of the pretreated fabric were and testing the physical and chemical properties of untreated and treated hemp fabric.Thus,the mechanism of hemp fabric on the image quality of inkjet printing was analyzed.The result are as follows:（1）Compared with SA,when the pretreatment solution of 1.5%XG,10%urea and2%Na HCO₃,the steaming time was 10min,the K/S values of the four color blocks（cyan,magenta,yellow and black）of the printed fabric increased by 4.26、1.67、3.98and 10.73,respectively.The warp and weft widths were reduced by 32.09μm and37.55μm,respectively.The printed fabrics showed higher color depth and fine line.At the same time,the wetting time of XG pretreated hemp fabric increased from 32.18s of SA pretreated to 79.89s.It mean that XG film structure built on the hemp fabric surface had a more hydrophobic surface,which effectively inhibited the diffusion and penetration of dyes,and improved the image quality of inkjet printing.（2）The urea-free CMG pretreatment agent（1.5%CMG and 2%Na HCO₃）was introduced to treat on hemp fabric.And the K/S values of the cyan,magenta,yellow and black color block of treated hemp fabric increased by 4.53、0.81、2.38 and 6.14respectively.The contact angle increased from 70.13°of SA pretreated hemp fabric to120.28°,and the wetting time increased from 32.18s to 706.1s.The wetting performance of the fabric had changed significantly,effectively inhibiting the diffusion of dye inks.The hemp fabric treated with CMG had a slight decreased in the rubbing fastness to moisture,and the other color fastnesses were maintained above 4.The fracture strength retention rates of warp and weft are 99.50%and 100.93%,respectively.Therefore,CMG pretreatment gave the fabric excellent color depth and color fastness,while the fabric breaking strength did not change significantly.In brief,natural polysaccharide polymer molecules as pretreatment agents on inkjet printing could effectively improve the image quality of hemp fabric,providing ways for industrial production of hemp fabric pretreatment.In addition,the research of urea-free pretreatment agent complied with the national energy-saving emission reduction,green environmental protection policy requirements.