Section 7 Textile Printing - 3

(h) The Digital Printing European Association of Silk Screen Printing Associations (PESPA) has held a digital printing conference for three consecutive years since 1997. The third meeting has more than 170 people in 22 countries. Every year, the United States also holds a textile digital printing conference. The Direct Digital Printing (DDP) at the International Textile Machinery Exhibition (ITMA) in 1999 in Paris, France has also become a major project. Although digital printing is still in its infancy, gradually replacing the screen printing technology that has already formed is an inevitable trend in the future.
1. Digital computer drafting With the development of computer technology and production, digital computer design and drafting and drafting have become quite popular in China. Compared with manual drafting and photo-making, it has the advantages of higher quality, faster speed, more convenient production, and lower cost, in particular, the quality of color separation and screening is much higher than manual and The level of photovoltaic production has become a widely used production method.
A series of work such as pattern design, color separation, screening, and filming on the computer must be completed by operating professional graphic design software and publishing software. Through-type software such as Adobe Illustrator, Photoshop, CorelDraw, etc. are mainly used for the design and production of image characters, but if you use domestic professional screen printing software such as Wenyuange, Mengtai and other systems will be more convenient.
The program for digitizing patterns through a computer is generally:
Graphic input → design and edit → output effect color → color separation → screening → set the screening angle → output (1) color separation To understand the primary color separation or spot color separation or color separation and other primary colors.
(2) Screening If the T-shirt printing is generally less than 60 lines, the number of screen lines depends on factors such as the characteristics of the printed material, the fabric and the color of the fabric. Paste printing is usually not suitable for screen printing. Under special circumstances, screen printing technology is used. The number of screen lines should be below 40 lines. The number of screens for water paste printing is generally about 50 lines. The number of hot melt ink screens can be selected between 35-60 lines. If the fabrics are darker, 35-45 lines can be used to increase the hiding power of ink. The number of foam inks and crystal ink lines should not be fine. The number of lines playing against white should be thicker than the number of lines of other colors. Due to the non-blocking nature of the hot melt ink, the screen of the 70-80 line can also be used.
(3) The dot pattern of printing usually adopts elliptical and circular dots. The angle of screening is usually 15°, usually starting from 5°. Such as spot color screening more than 6 colors, from the 80 ° 20 ° interval starting from the seventh color screening angle (still separated by 15 °).
(4) Producers also need to print a positive picture that is a positive picture, which is different from a normal printed manuscript.
(5) The main method of output is 1 printer drawing. Ink-jet printers, laser printers, and wax-jet printers can all be used. The cost of laser printers is higher but the cost of use is lower. The cost of ink-jet printers is low but the cost of ink is high. Wax-jet printers (also called dry printers) ) The cost of acquisition costs is high. In terms of the quality of the drawn film, the wax-jet printer is the best, the laser printer is also good, and the inkjet printer is poor;
2 engraving machine engraving. That is, a computer cutting plotter is used to sculpt a pattern on the red tear film, and a cutting plotter may be used to engrave the pattern on the red (black) self-adhesive paper and then attached to the PVC film, but the accuracy of the engraving machine is not as good as that of the printer. The printing with less precision is required.
3 laser phototypesetting. Laser photocopying is the method of making the highest quality film. Only because the laser photocopying equipment is quite expensive, only the platemaking center with a certain scale will be configured, so generally only the edited files are photographed and the film is set off. The price is higher than the printer picture, but the quality is much better.
2. Digital to plate technology (CTP)
There are three main types of application technologies in screen printing:
(1) Ink jetting (wax) CTP plate making This technique is to print images on a silk screen pre-printed with a photosensitive resin by a computer-controlled lithographic ink jet or wax printer. This ink-jet image replaces the role of the plate-making film, and is made into a printing screen after exposure and development. Both the United States and Switzerland have produced inkjet (wax) CTP platesetters. In the United States, Gerber Company produced a CTP platemaking system dedicated to the printing and typography of T-shirts; Screen Jet (maximum plate area 65 cm x 95 cm).
(2) The difference between spray CTP plate making and inkjet CTP is that it sprays the photosensitive polymer glue on the screen plate. The image is the opposite of ink-jet printing. After the photosensitive plate is cured, it becomes a printing screen plate.
(3) Laser CTP plate making means that the computer controls an optical system to scan a prepared photolithographic screen with a modulated laser beam. The scanned point of the laser beam is cured by exposure, and after printing, it becomes a printed screen plate.
Compared with the current platemaking technology, CTP technology has obvious advantages. The elimination of the work of making negatives in plate making was quick and convenient, and the quality was improved. The transmission and preservation of data were more reliable and easier, and its market prospect was very broad.
3. Digital jet printing technology Digital jet printing is a new technology that has developed rapidly in the past 10 years and is the most challenging traditional printing technology. The system according to the pre-determined listed, will be pigmented ink pressure or piezoelectric driven, The process of continuous jetting to the printed fabric through nozzles and the computer-based color separation system to form patterns, also known as non-contact non-contact printing or digital printing. Compared with traditional printing methods, it has the following advantages:
1 can completely eliminate the printing screen, cancel the complex plate-making process.
2 to save a lot of production and network storage space, covers an area of ​​only a few tens of traditional printing methods can be continuous inkjet printing 16h without operator supervision;
3 can print larger patterns;
4 wide spectrum, no restrictions on the number of sets. And to ensure the consistency of proofing and mass production, the proofing process by the computer automatically records color data, batch production of color data according to proofing data preparation, safety can maintain the same color;
5 can achieve rapid response of the sample and large-scale production, can print any effect of the pattern patterns, paintings, photographs, etc., rich colors and layers, realistic images;
6 On-demand ink-jet, the dye is almost not wasted, the production process has no waste water, energy consumption is extremely low, the entire production process can realize the environmental protection processing process, and is in line with the “green” theme of the 21st century.
(1) Principle of digital jet 1 Continuous jet CIJ (Continuous Ink Jet). The continuous jet principle is to apply a high-frequency oscillating pressure to the ink, so that the ink is ejected from the nozzle to form a uniform continuous droplet flow. An electric field is provided at the nozzle at the same time as the pattern photoelectric conversion signal. The ejected droplets are selectively charged in the charging electric field. When the droplet stream continues to pass through the deflection electric field, the charged droplets are deflected by the electric field. The uncharged droplets continue to maintain straight flight conditions. Droplets flying in a straight line cannot reach the substrate to be printed and are recovered by the accumulator; charged droplets are ejected onto the substrate to be printed;
2 on-demand jet DOD (dro on Demand). The working principle of the on-demand jet printing system is that when printing is required, the system applies high-frequency mechanical force, electromagnetic or thermal shock to the color ink in the nozzle, so that it forms tiny droplets to be ejected from the nozzle and is controlled by the computer. To the set pattern. Drop-on-demand The most widely used thermal inkjet technology. It relies on heat pulses to generate ink droplets. The computer controls a heated resistance wire to the specified temperature, causing the ink to evaporate out of the nozzle. Another DOD technique is a piezoelectric injection system that is controlled by a computer to impose a potential on the piezoelectric material so that the piezoelectric material compresses in the direction of the electric field and expands in the vertical direction so that the ink is ejected.
(2) Digital jet printer 1 High-speed digital jet system Print Master PM2200 (produced by PERFECTA company, Switzerland). The system is characterized by continuous ink supply, which can be used for proofing and batch printing. The main properties are shown in Table 4-25.
Table 4-25 Main Features of High Speed ​​Digital Injection System PM2200

2 digital jet printing machine A'tex-Print Tex-1300/1600 (produced by Hangzhou Honghua Computer Technology Co., Ltd.). The machine is characterized by no need for plate making, direct printing, and can be used for proofing and small batch production. The main performance is shown in Table 4-26.
Table 4-26 Main Features of Digital Jet Printing Machine Tex-1300/1600