Industrial Printing 4

Printing > Fourth Quarter Textile Printing

Plates are transferred to textiles by printing plates such as stencils, spirals, or screens to form pattern patterns of various colors. People call them printing and dyeing, but in terms of its essence, printing and dyeing technology is entirely a printing technology in the printing and dyeing industry. The specific application, so it is also possible to call it a textile printing.

Fabric printing has a long history in China. As early as the Western Han Dynasty more than 2,000 years ago, people have mastered the technique of printing patterns on fabrics. This can be proven from the three-color overprint “gold and silver printed yarn” unearthed at the Western Han Dynasty Tomb in Mawangdui, Changsha, China. For more than 2,000 years, traditional hand-printing techniques such as ancient woodblock prints, stencil prints, and paper-type prints have continued on the Chinese land.

For more than 40 years, great changes have taken place in China's textile printing technology. In the 1950s and 1970s, copper cylinder printing was the mainstay. Since the 1970s, due to the rapid development of screen printing technology, screen printing has been widely used, and new transfer printing technologies have emerged. Various kinds of printing technologies are competing in the printing and dyeing industry, printing and dyeing out beautiful silk fabrics, and making the space where people and people live is gorgeous.

First, type printing

China is a country with a vast territory. In many places, it has also maintained its unique costume culture and traditional printing and dyeing techniques hand-dyed and dyed. This is the case with batiks that are popular in the southwest and the type prints used in some places.

Pattern printing is the prototype of ancient stencil printing. The plate is made of tung oil or lacquer to prevent the paper from being water-repelled, made into paperboard, and then stenciled on cardboard. All the patterns are carved into the air. In order to keep the layout intact, some joint ribs should be properly reserved when cutting. A pattern needs a few colors to make a few plates. A color modulates a color paste. During printing and dyeing, the hand-held printing plate is positioned on the substrate, and the colorant is applied to the substrate with a brush. This kind of printing and dyeing methods, from drawing artwork, to engraving, and painting color pastes, are manual operations. Because they are easy to make and use, they are flexible enough to use. Although not as highly industrialized as the later cylinder printing, they are suitable for small towns or even rural areas. Workshop-style production, so far still has applications in some areas, such as the production of towels, curtains, headscarves, sheets and the like of rural dyeing fabrics.

Second, roller printing

Roller printing uses gravure printing principles. As early as the beginning of the 20th century, with the rise of the modern textile printing and dyeing industry in China, roller printing technology was also developed in coastal industrial cities such as Shanghai. Until the 1960s, roller printing has always occupied an important position in the printing and dyeing industry.

1.Preparation of the printing drum The printing drum is also called the flower cylinder, and because it is a hollow copper, it is also called a copper drum. It consists of a copper-zinc alloy with a hardness of HB78-84°. The length of the new drum ranges from 32 inches (813 mm) to 50 inches (1276 mm) and 402 to 446 mm in circumference (128 to 142 mm in diameter). In order to facilitate loading and unloading, the roller has a hollow cone, with a taper of about 1288, and a protruding key so that when the roller is loaded into the steel shaft, it is pinned with the key groove on the steel shaft. Before the engraving of the roller, the old model car will be put on a lathe. Each time the drum is used, the circumference is reduced by approximately 1.5 to 2.5 mm. When the circumference of the drum is less than 350 mm (approximately 112 mm straight), it cannot be reused. After the roller car is finished, it must be polished on the grinding machine to make the surface of the roller smooth like a mirror. After dressing, wrap it in paper and wait. The circumference of the drum gradually decreases with the number of uses, but the number of drums of a group of patterns must be equal to the circumference.

2. The engraving of the drum The engraving of the drum includes a reduction engraving method, a photographic etching method, and a steel core engraving method. However, the use of more or reduce the carving method and photographic corrosion method.

(1) Reduce the engraving method. The designed pattern was projected on a zinc plate with a magnifying machine to enlarge, and the pattern was painted on a zinc plate. The enlarged pattern was engraved on the zinc plate by hand engraving or chemical etching.

Before the engraving, a layer of dry wax prepared with asphalt, rosin, beeswax, turpentine, etc. is coated on the drum surface. The engraving of the drum is performed on a dedicated shrinking machine. The machine is manually operated to reduce the machine. When the steel stylus on the workbench is moved on the zinc plate in accordance with the pattern, the diamond pin on the frame roller is engraved with a wax layer on the surface of the copper roller to make a reduced pattern. The design of a few colors, it is necessary to sculpt a few rollers.

The pattern on the printing drum is connected end to end in the circumferential direction. This point is carefully calculated from the design of the pattern to the staking of the zinc sheet to the copper drum.

Reducing the carving is mechanical carving, and the process equipment is relatively simple and easy to grasp. However, the patterns made by this carving method are mostly limited to lines, point-and-draw types of expressions, lacking in level and space change.

(2) Photographic engraving. This is a relatively mature process that has been applied since the 1930s.

First, the designed pattern original is taken by a plate-making camera to produce a negative film. For color manuscripts, color separations are generally made manually, with continuous changes also useful for color separation and over-screening. The dots on the fabric are printed on the paper to be thicker than the printed lines on the paper. The number of screens is between 20 and 40 lines per cm. Generally, 30 lines/cm are more commonly used.

Fabric printing and dyeing patterns are often repeated periodically, so the plate-making camera shoots the negative film of the unit, and it is necessary to make a positive film on the continuous dryer according to the requirements of the pattern distribution of the surface of the copper roller.

First, apply the emulsion to the surface of a clean, shiny copper roller. Before the 1960s, gelatin was used in combination with ammonium dichromate. After the 1960s, domestic polyvinyl alcohol began to be supplied in large quantities and was gradually converted to polyvinyl alcohol. Its composition is as follows: