The principle and technological process of digital inkjet printing

At present, inkjet printing is more and more used in all aspects of life, and some people regard inkjet as the best potential printing method in the future. Xiaobian summarizes the working principle and process of digital inkjet printing for you.

Digital inkjet printing, also known as color inkjet printing, is to input the required graphics to the computer through an input device such as a scanner or digital camera, edited and processed by the electronic color separation system, and then the computer controls the inkjet system directly Dyes or pigments are sprayed onto fabrics for printing. Inkjet printing can be divided into two types: continuous inkjet and on-demand inkjet based on the principle of inkjet.

1. Continuous jet

The principle of the continuous jet type is to apply a high-frequency oscillating pressure to form a uniform and continuous droplet flow from the nozzle. An electric field that changes synchronously with the pattern photoelectric conversion signal is provided at the nozzle. The ejected droplets are selectively charged in the charging electric field. When the flow of droplets continues to pass through the deflection electric field, the charged droplets are deflected under the action of the electric field, and the uncharged droplets continue to fly in a straight line. The droplets flying in a straight line cannot reach the substrate and are recovered by the liquid collector. The charged droplets are ejected onto the substrate to complete the printing.

2. On-demand spray

The working principle of the on-demand jet printing system is that when printing is required, the system applies high-frequency mechanical force and electromagnetic thermal shock to the nozzle to form tiny droplets and eject them from the nozzle. Fixed pattern. The most widely used on-demand jet is thermal inkjet technology, which relies on thermal pulsation to generate ink droplets, and a computer controls a heating resistance wire to a specified temperature, resulting in a gas-voltage jet system, that is, the computer controls the conductive material Applying a potential causes the conductive material to compress in the direction of the electric field and expand in the vertical direction, thereby ejecting.

3. The process of digital inkjet printing

Inkjet printing requires not only high-precision nozzle technology and high-precision control technology, but also ink with high purity, high concentration, high fastness and high stability. The process of inkjet printing depends on the use. Generally, acid dyes are mainly used for carpet printing, disperse dyes are mainly used in polyester fabrics, and reactive dyes are mainly used in cotton fabrics. The following is an example of the process of inkjet printing of reactive dyes used on cotton fabrics.

Fabric pretreatment → drying before printing → inkjet printing → drying after printing → steaming.

The pretreatment of the fabric is mainly due to the wettability of the fabric and the capillary effect between the fibers. In conventional fabric printing pastes, appropriate printing fillers must be used to prevent seepage. The general inkjet printer can only use low-viscosity water-based ink. If it is directly printed on the fabric, the dyeing solution will permeate in all directions, so the printed fabric must be properly pretreated. When spray printing, special software is used to print lines and patterns at an appropriate resolution. The post-processing of printed fabrics is mainly to improve their color fastness.