The traditional printing process includes four processes: pattern design, fountain engraving (or screen plate making, rotary screen making), color paste preparation and pattern printing, post-processing (steaming, desizing, washing).
Graphic design
1. According to the use of the fabric (such as men's clothing, women's clothing, ties, scarves, etc.), grasp the style, tone and pattern of the pattern.
2. Coordinate with the style of the fabric material, such as the fineness and color purity of silk products and hemp products are very different.
3. The expression technique, color registration and the structure of the pattern should meet the printing process, the width of the fabric, the direction of the silk thread, the cutting and sewing of the garment and other factors. Especially with different printing methods, the pattern style and expression techniques are also different. For example, the number of color sets of roller printing is 1 to 6 sets, and the pattern width is limited by the size of the cylinder; while the number of color sets of screen printing can reach more than 10 sets, arranged in a row. The cycle is large enough to print a single fabric, but it is not suitable for designing neat and regular geometric patterns.
4. Pattern style design should consider market and economic benefits
Fountain engraving, sieve plate making, rotary screen making
Fountains, screens and rotary screens are specific equipment for the printing process. In order to make the designed pattern produce the corresponding pattern on the fabric under the action of the color paste, it is necessary to carry out the process engineering such as flower cylinder engraving, screen plate making and rotary screen making, so as to form the corresponding pattern model.
1. Fountain engraving: The drum printing machine prints and engraves the pattern on the copper fountain, and there are twill lines or dots in it to store the color paste. The process of engraving a concave pattern on the surface of a copper roll is called fountain engraving. The fountain is made of iron hollow rollers plated with copper or cast with copper, the circumference is generally 400-500mm, and the length depends on the width of the printing machine. Pattern engraving methods include hand engraving, copper core engraving, reduced engraving, photographic engraving, electronic engraving, etc.
2. Screen plate making: Flat screen printing needs to make the corresponding screen. Flat screen plate making includes the production of screen frame, stretch screen and screen pattern. The screen frame is made of hard wood or aluminum alloy material, and then a certain specification of nylon, polyester or silk fabric is tightened on the screen frame to form a screen. The production of screen patterns is commonly used by photosensitive method (or electronic color separation method) or anti-paint method.
3. Rotary screen production: rotary screen printing needs to make a rotary screen. First make a perforated nickel mesh, and then use a circular metal frame to cover both ends of the nickel mesh to tighten the nickel mesh. Then apply photosensitive glue on the nickel screen, wrap the color separation piece of the pattern tightly on the nickel screen, and use the photosensitive method to make a circular screen with a pattern.
Color paste preparation and pattern printing 4. Post-processing (steaming, desizing, washing)
After printing and drying, it is usually steamed, developed or fixed, and then desizing and washing are carried out to fully remove the paste, chemicals and floating color in the color paste.
Steaming is also called steaming. After the printing paste is dried on the fabric, in order to transfer the dye from the paste to the fiber and complete a certain chemical change, it generally needs to be steamed. During the steaming process, the steam first condenses on the fabric, which increases the temperature of the fabric, swells the fibers and the paste, dissolves the dyes and chemicals, and some chemically react. At this time, the dyes are transferred from the color paste to the fibers, thereby Finish the dyeing process.
In addition, due to the existence of paste, the dyeing process of printing dyes is more complicated, and the steaming time is longer than that of pad dyeing in dyeing. Steaming process conditions also vary with dye and fabric properties.
Finally, the printed fabric should be fully desizing and washing to remove the paste, chemical reagents and floating color on the fabric. The paste remains on the fabric, making the fabric feel rough. The floating color remains on the fabric, which will affect the color brightness and color fastness.