What is the printing process and what is it used for?

Printing process is the process of printing patterns on textiles with dyes or pigments. Printing can be divided into fabric printing, top printing and yarn printing, with fabric printing as the main one. Top printing is used to make mixed color tweed; Yarn printing is used to weave fabrics with special color patterns. Fabric printing has a long history. China used stencil printing during the Warring States Period (see History of Dyeing and Finishing in China). India had block printing in the 4th century BC. Continuous gravure cylinder printing began in the18th century (see cylinder printing). Screen printing is developed from hollow board, which is suitable for small batch and multi-variety printing of deformable fabrics. Printed cloth is an artistic product, and the corresponding printing process should be selected according to the designed pattern. There are three kinds of printing in common use: direct printing, resist printing and discharge printing. Direct printing is to print dyes or pigments directly on white or light-colored fabrics, and then obtain patterns through post-treatment, such as steaming. The process is short and widely used.

Anti-dye printing is a substance printed on fabric to prevent dyes from dyeing or developing color, and then dyeing or developing color, so as to obtain patterns on dyed fabric. Discharge printing is a printing process that prints on dyed fabrics, eliminates the substances of dyed dyes, and obtains patterns on dyed fabrics. Printing paste consists of dye (or pigment), hygroscopic agent, cosolvent and original paste. The function of printing paste is to make the paste have certain viscosity and fluidity. Made of hydrophilic polymer paste, commonly used pastes include starch, starch degradation products (white dextrin and yellow dextrin), starch ether derivatives, sodium alginate (or ammonium), hydroxyethyl Arabic gum, dragon gum, cellulose ether, synthetic polymer electrolyte, etc. Emulsified paste made of water, kerosene and emulsifier is sometimes used as printing paste. Printing paste should have good stability to chemicals in color paste, do not react with dyes, have certain adhesion to fibers, and be easy to wash off from fabrics. The viscosity of printing paste depends on the properties of the original paste. When printing, it is difficult to print fine lines when the viscosity of color paste drops too much, and it is difficult for color paste to pass through the fine holes of screen when the viscosity is too high.