Research On Surface Modification And Film-forming Mechanism Of Cellulose-based Blended Fabrics In Inkjet Digital Printing

Compared with traditional screen printing,digital printing eliminates cumbersome procedures such as plate making and color matching through computer control of the nozzle.It has the advantages of low energy consumption,low pollution,less restrictions on printing patterns,and wide color gamut.It can be used in production and life.There is a trend of beginning to spread.In the contemporary era of individualization and customization,it is especially suitable for design with multiple colors and production in small scale.Among them,the pigment digital printing technology is widely applicable to various blended fabrics and does not require washing or high-temperature baking to fix the color directly.It has many advantages such as stable printing color and high fastness to sunlight.With the increasing use of colors and the increasing complexity of graphic design,in addition to enhancing the color depth and color fastness,higher requirements for printing accuracy are also put forward.The outline definition of digital printing patterns is usually related to the spreading and permeation behavior of micro ink droplets on porous fabrics.Appropriate pretreatment methods and processes can effectively inhibit the diffusion of ink and weaken this by changing the physical and chemical properties of the interior and surface of the fabric.The phenomenon of bleeding,which in turn significantly improves the printing accuracy.The cellulose-based blended fabric was taken as an example and two pretreatment modification agents were selected,which were cationic modifier and fluorine-containing water repellent,to explore the influence mechanism different pretreatment schemes on the results of the micro ink drop test,and to analyze under what circumstances will produce a synergistic effect.Experiments on the element composition,chemical potential,surface morphology and pore size distribution of the fabric surface in a variety of pretreatment schemes such as separate use,mixed use,and sequential use of the two respectively,and through exploring the behavior mechanism of ink droplet spreading,penetration,and diffusion,The different contact angles,spreading time,front and back K/S values,spreading area,different diffusion modes,ring formation,and edge definition were explained.Experiment results show that the sharpness of the bleeding edge after the ink drop is completely spread is mainly determined by the relative speed of the vertical penetration and lateral diffusion behavior of the ink drop in the fabric;and the spreading area of the ink drop is not only related to the ink droplet’s ability to diffuse and penetrate in the fabric,but also to the wetting properties of the fabric surface.The fabrics treated separately with 1 % cationic modifier and 0.05 % fluorine-containing water repellent agent could make the final ring shape and color development of ink droplets reach the best effect.When the optimal concentrations of1 % and 0.05 % were used for pretreatment in the form of a blending solution,a synergistic effect could occur,and the wicking effect of ink droplets could be suppressed to the greatest extent.The inner ring formed after the ink drop completely spreading had a clear edge contour and a higher color depth,and the total spread area was also significantly reduced.As the amount of ink drops decreases from 5 μL to 1 μL,the outer ring of the ink drop gradually disappeared,and the improvement of the ink drop test results was more significant.In addition,the pigment ink-jet digital printing experiment was carried out on the fabrics of each pretreatment scheme,and its influence on the printing accuracy,color performance,color fastness,post-printing style and fabric tensile strength was explored.The results show that the blending scheme can not only achieve the clearest line edges,obtain the thinnest actual line width value under 3 px,5 px,7 px print width,but also improve the color characteristic value of the CMYK color block after printing,with the highest color depth K/S value,the synergistic effect produced by the blending pretreatment scheme.In this scheme,the dry and wet rubbing fastness as well as soaping fastness of the printed fabric had been improved,which could reach grade of 4-5,3-4 and 4 respectively,and retain its original softness to the greatest extent The texture,smoothness,drape hand-feel style,the original strength of the fabric had also been improved.The feasibility of the pretreatment of the blending scheme was verified,which provided theoretical and experimental support for its application in high-performance blended clothing fabrics and laid a certain foundation.