Fabric printing process and characteristics and Classification of textile printing

Fabric printing is forming patterns on fabrics through screen printing technology. Standard printing methods include stencil printing, screen printing, drum-type rotary screen printing, transfer printing, and multi-color dyeing printing. Among them, screen printing originated from stencil printing, which was initially mainly manual operation and then gradually developed into semi-automatic and fully automated production, and finally evolved from flat screen printing to rotary screen printing. Therefore, screen printing can be further divided into two types: flat screen printing and rotary screen printing.

   Features of fabric printing:  

Fabric printing is the printing of dyes or coatings on fabrics through chemical or physical methods to form colorful patterns. Although from the perspective of the combination of dyes and fibers, printing and dyeing have similarities, both of which make dyes react with fibers, printing requires the precise presentation of patterns in specific parts of the fabric. In contrast, non-dyed parts must be kept clean to avoid pollution. Therefore, printing is not just local dyeing; it also requires precise control and specific processes to achieve pattern clarity and color uniformity.

To achieve these effects, the printing process usually requires pre-mixing the dye with adhesives and chemicals to make a printing paste. After the printing paste is printed on the fabric through the screen, a polymer film will form on the fabric's surface to prevent excessive penetration of the dye. Then, after drying and steaming, the dye penetrates the fiber and fixes it, thereby ensuring the pattern's clarity while improving the fabric's feel, gloss, and color fastness. Finally, sufficient water washing removes the excess auxiliaries, printing paste, and floating color on the fabric so that the printed fabric has bright colors and clear flower outlines.

   Selection of printing dyes: 

In the printing process, the dye selection differs from the dyeing process. The dyes used for printing have relatively low requirements for leveling, and their leveling effect mainly depends on the preparation and operation technology of the printing paste. However, the solubility requirements for dyes are more stringent. This is because the water content of the printing paste is limited. During the steaming fixation process, the dye needs to be redissolved under the action of a small amount of condensed water before it can diffuse through the pulp membrane and penetrate the fiber. For this reason, dyes suitable for printing usually have low molecular weight, good diffusivity, and high color fastness. In addition, for electrolyte-sensitive slurries, the electrolyte content in printing dyes should be controlled at a low level as much as possible.

Through the above process, fabric printing can present high concentration, brightly colored, and clearly defined fabric patterns, and it has excellent durability and feel.

According to different standards, fabric printing can be classified in many ways.

     1. Classification by printing form

 Classification of fabric printing process

Direct printing: Direct printing is a printing method in which a printing paste containing dyes or pigments is directly printed on white or light-colored fabrics, and the pattern is obtained after post-processing. This method is relatively simple, low-cost, and suitable for most fabrics.

Discharge printing: Discharge printing first dyes the fabric as a whole, then uses a discharge paste that can destroy the dye to print in specific areas to restore these areas to white or other colors. The discharge printing effect is pleasing, but the process is complicated, and the cost is high. It is usually used for high-end fabrics such as silk.

Resist printing: Resist printing is first printing a layer of color paste on the fabric to prevent dye coloring and then dyeing it. This way, the resist area will retain the original color or present a new one. The resist printing process is relatively complicated and is usually used in fabric printing for specific needs.

Pulp printing: Pulp printing is printing a color paste containing acidic or alkaline substances on the fabric so that part of the fiber decomposes or dissolves, forming a unique texture effect. This process is usually used to create special effects printing.

Penetration printing: Penetration printing uses the characteristics of dyes that penetrate fabric fibers so that the printed pattern not only stays on the surface but penetrates the entire fabric. This process is usually used for light and breathable fabrics, such as summer clothing.

Microparticle printing: Microparticle printing is to fix tiny pigment particles on the fabric's surface through a unique process to form a clear and delicate pattern. This process is particularly suitable for printing with high precision requirements.

Classification by fabric form

Sheet printing: Sheet printing refers to printing on cut fabric sheets, which is suitable for industrial processes for mass production. Sheets can be cut into pieces according to the size of the finished product, or they can be printed in batches.

Finished product printing: Printed directly on already-made clothing, shoes, hats, bags, and other products, usually using a dedicated screen printing machine or through transfer technology.

   2. Classification by printing equipment

Screen printing: Screen printing uses a screen plate to transfer color paste to the fabric through the mesh, a widely used printing method. According to the operation method, it can be divided into:

Manual printing: Manual screen printing operates the screen and color paste, suitable for small-scale production and high-precision printing.

Automatic screen printing: Automatic screen printing machines improve production efficiency through mechanized operation and are suitable for mass production. Standard automatic screen printing equipment includes flat and rotary screen printing machines.

Roller printing: Roller printing is the application of color paste on the surface of a drum with a pattern engraved on it and the transfer of the pattern to the fabric through a rotating drum. Roller printing is fast and suitable for mass production. It is widely used in printing fabrics such as cotton and polyester.

3. Special printing: Special printing methods include stencil printing, transfer printing, etc. Stencil printing is suitable for small-scale and multi-variety production, while transfer printing includes pigment transfer, sublimation transfer, etc., and is widely used in various fabrics.

   3. Classification by printing processing method

 Sheet printing processing

Manual screen printing: The color paste is scraped onto the sheet manually, which is suitable for small-batch production.

Automatic screen printing: Using automatic equipment for large-scale sheet printing can improve production efficiency and printing quality.

Finished product printing processing

Direct printing method: Use a particular printing machine to print directly on the finished product, such as printing patterns on ready-made clothes, hats, and other products.

Indirect printing method: First, print the pattern on the paper, then transfer the pattern to the finished product through thermal transfer or other methods.

   4. Classification by printing machine

The printing machine is a key piece of equipment in the fabric printing process. According to its operation mode and scope of application, it can be divided into the following types:

 Screen printing machine: including manual, semi-automatic, and fully automatic screen printing machines. Manual screen printing machines are suitable for small batch production, while automatic screen printing machines are suitable for large batch production.

 Roller printing machine: single-sided and double-sided roller printing machines, mainly used for large batch production, especially suitable for printing long fabrics.

 Special printing equipment, such as stencil machines, transfer printing machines, etc., are used for specific printing processes and fabric types.