Research On Digital Printing Pretreatment

In order to obtain good printing quality and create a condition for the dye fixation in the fiber, the pretreatment for fabric was very necessary before digital printing. This paper studied three aspects of digital printing:the pretreatment of cotton knitted fabric, wool knitted fabric and polyester woven fabric.In the process of digital printing on polyester fabric, three aspects had been researched:using sodium alginate and thickener for the pretreatment via knife coating respectively, exclusively applying controlling surface tension agent for the pretreatment via padding, employing the mixture of thickener and control surface tension agent for the pretreatment via knife coating. The samples were inspected capability of anti-bleeding and colorability of dye. The result showed that the direct ink-jet printing on polyester fabric was achievable by the pretreatment of controlling surface tension agent agent. And it was not influence of colorability of dye on the fabric.In the process of digital printing on cotton fabric, the pretreatment, which applied sodium bicarbonate solution or a mixture of urea and sodium bicarbonate solution through padding and the paste comprised of sodium alginate, urea and sodium bicarbonate via knife coating, had been investigated. By means of the capability of anti-bleeding and value of K/S, digital printing ability of the samples were characterized. The result showed that the anti-bleeding effect of padding was similar to knife coating. But the K/S value of padding was lower than knife coating.In the process of digital printing on wool fabric, the pretreatment by knife coating applied the paste that constituted sodium alginate, urea and ammonium or sodium bicarbonate. In addition, in order to shorten the wool fabric steaming fixation time, hydrogen peroxide was used in oxidation treatment for the scale of wool fiber. After the pretreatment, the samples’digital printing ability was evaluated through the K/S value, white degree and tensile breaking force. The result showed that the pretreatment of wool fabric using alkaline paste was viable. The fixation time of two-step short streaming process could be shortened to 40 min. The K/S value of the process of cold batch and short streaming using alkaline paste could achieve the best.