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Can Digital Printing Replace Screen Printing?

2016/7/15 17:54:00 141

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In recent years, digital printing Rapid development and great potential to replace screen printing. What are the differences between the two printing processes? How do you know and choose them? Here is a detailed analysis of the technical characteristics and development prospects of digital printing and screen printing.

Printing refers to the use of dyestuff Or paint can be formed on the surface of the fabric. With the development of printing technology, many printing processes such as screen printing, rotary screen printing, roller printing, digital printing have coexisted. Different printing processes are different in scope of application, and there are differences in process characteristics. Printing equipment and consumables are also different. Screen printing, as a traditional printing process, has a wide range of applications, and accounts for a relatively high proportion in the printing industry. In recent years, digital printing has developed rapidly, and many people feel that there will be a tendency to replace silk screen printing. What are the differences between the two printing processes? Here are the differences between digital printing and screen printing.

There is not much difference in the type of substrate material.

Digital printing is divided into five categories: acid digital printing, reactive digital printing, digital printing, disperse heat transfer printing and disperse direct injection digital printing. Digital printing acid ink is suitable for wool, silk and other protein fibers. Nylon fiber And other fabrics. Digital printing reactive dye ink is mainly applied to digital printing of fabrics such as cotton, linen, viscose fiber and silk fabrics. It can be applied to digital printing of natural fabrics such as cotton fabrics, real silk fabrics and wool fabrics. Digital printing ink is suitable for digital ink jet printing of cotton fabrics, silk fabrics, chemical fibers and blended fabrics, knitwear, sweaters, towels and blankets. Digital printing heat transfer ink is suitable for transfer printing of polyester, non-woven fabrics, ceramics and other materials. Digital printing direct spray disperse ink is suitable for digital printing of polyester fabrics, such as decorative cloth, banner cloth, banners and so on.

Traditional screen printing does not have much advantage over digital printing in terms of the type of printed material. First, the printing size of traditional printing is limited. The largest inkjet width of large industrial digital inkjet printing machine can reach 3~4 meters. Printing can be carried out without interruption, and they can even form a whole production line. Two, on some materials, the traditional water-based ink printing can not achieve better performance. Therefore, only solvent based ink can be used for printing. Digital printing can be used in any material for ink jet printing, thus avoiding the use of flammable and explosive non circulating solvents.

The color of digital printing is brighter.

The biggest advantage of digital printing is mainly in the fineness of colors and patterns. First of all, from the perspective of color, digital printing ink is divided into dye and pigment based ink. The dyestuff is brightly coloured and superior to pigment. Acid dye printing, reactive digital printing, disperse heat transfer printing and disperse direct injection digital printing are all dyestuff inks. Although the pigment digital printing is made of pigments as coloring agents, nano pigment pigments are used. Specific ink, as long as completes the matching special ICC curve, the color display can reach the extreme. The color of traditional screen printing is based on four color dots, and two is controlled by pre press ink. The color rendering power is not as good as digital printing. In addition, in digital printing, pigment ink is made of nano scale pigment paste, and dyestuff ink is water-soluble. Even disperse thermal sublimation transfer ink, the pigment is nano scale.

The fineness of digital printing is related to the characteristics of inkjet printhead and printing speed. The smaller the ink droplet of the inkjet printing head, the higher the printing accuracy. The ink droplet of the EPSON micro piezoelectric printing head is the smallest, while the industrial head's ink droplet is larger than it, but it can also print the image with a precision of 1440 dpi. In addition, the faster the printing speed is, the smaller the printing accuracy is. Screen printing requires film plate making. The errors in the plate making process and the mesh number of the screen affect the fineness of the pattern. Theoretically, the smaller the screen size is, the better. But ordinary printing uses 100~150 screen. The number of four color dots is 200 mesh. The higher the number of eyes, the greater the probability of plugging the water-based ink. This is a common disease. In addition, the accuracy of the printing plate has great influence on the fineness of the printing pattern, and the printing is relatively good, but manual printing is difficult to control.

Obviously, color and fine graphics are not the advantages of screen printing. Their advantages are special printing paste, such as gold, silver, pearlescent color, crack effect, gilding flocking effect, suede foaming effect and so on. In addition, screen printing can print 3D stereoscopic effect, which are difficult to achieve in digital printing at present. Besides, digital printing is difficult to make white ink. At present, white ink is mainly maintained by imported ink, but printing on dark cloth is not acceptable without white. This is the difficulty to popularize digital printing at home.

  Digital printing soft touch screen printing high color fastness

The main properties of printing products include surface quality, namely hand feeling (softness), sticky resistance, resistance to friction, color fastness to rubbing, color fastness to soaping, environmental protection, whether formaldehyde, azo, pH, carcinogenic aromatic amine, o-phthalic acid two ester etc. GB/T 18401-2003 "national textile product basic safety technical specification" has made clear stipulations to some of the items listed above.

Traditional screen printing, besides water slurry and discharge printing, has a strong sense of coating for other types of printing. This is because the resin content in the printing ink formulation is high as binder, and the amount of ink is relatively large. Digital printing is basically uncoated, and the printing is light, soft and sticky. Even the digital printing of paint, because the resin content in the formula is very few, basically will not affect the handle. Acidic digital printing, reactive digital printing, disperse heat transfer printing and disperse direct injection digital printing are all non coated and do not affect the original fabric feel.

Whether in traditional water-based printing ink or pigment printing ink, resin as adhesive, on the one hand is used to increase the adhesive fastness of coating and fabric, so that it is not easy to crack and fall off after washing. On the other hand, resin can wrap pigment particles and make it hard to decolorization. In traditional printing ink and paste, the resin content is 20%~90%, usually 70%~80%, while the pigment printing ink in digital printing ink contains only 10% resin. Obviously, theoretically speaking, the rubbing fastness and soaping fastness of digital printing will be worse than traditional printing. As a matter of fact, the color fastness of digital printing is very poor after a certain post-processing, especially the color fastness to wet rubbing. Although the color fastness to soaping of digital printing is sometimes tested according to the GB/T 3921-2008 test for color fastness to soaping fastness, there is still a distance from the washing fastness of traditional printing. At present, digital printing still needs further exploration and breakthroughs in terms of color fastness to rubbing and color fastness to soaping.

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High cost of digital printing equipment

There are mainly 3 types of printers used in digital printing. One is EPSON tablet machine modified tablet machine, such as EPSON T50 modified tablet machine, this type of machine is mainly used for small format printing ink of pigment ink, the cost of these models is much cheaper than other models. The two is the printer that loads EPSON DX4/DX5/DX6/DX7 series inkjet printing head. Among them, DX5 and DX7 are the most common ones, such as MIMAKI JV3-160, MUTOH 1604, MUTOH 1624, EPSONF 7080, EPSON S30680, etc. the cost of each printer purchased by these models is about 100 thousand yuan. At present, the price of the DX4 printhead market is 4000 yuan each, and the price of the DX5 print head market is more than 7000 yuan each, and the price of the DX7 print head market is 12000 yuan each. The three is the industrial inkjet digital printing machine. The representative machines include KYOCERA Kyocera industrial nozzle digital printing machine, Seiko SPT nozzle digital printing machine, knokicai industrial nozzle digital printing machine, SPECTRA industrial spray head digital printing machine, etc. the printer purchase cost is generally high. Each brand's print head has a single market price of more than 10 thousand yuan, and a print head can only print one color. That is to say, if you want to print four colors, one machine will have to install four printheads, so the cost is very high.

Therefore, the cost of digital printing equipment is very high, and inkjet printhead as the main consumables of digital inkjet printer, the price is extremely expensive. The market price of digital printing ink is much higher than that of traditional printing materials, but the printing area of 1 kilograms of ink output is unmatched with the printing area of 1 kilograms of ink. Therefore, the cost comparisons in this respect depend on the type of ink used, the specific printing requirements and the printing process.

In traditional screen printing, when manual printing is done, the screen and glue are scraped as expendable products. In traditional printing machines, imported Octopus printing machines and elliptical machines are more expensive than domestic ones, but the domestic models are becoming more and more mature, and they can also meet the requirements of production and use. If it is compared with inkjet printer, its purchase cost and maintenance cost will be much lower.

Screen printing needs to enhance environmental protection.

In terms of environmental protection, the environmental pollution caused by traditional screen printing is mainly reflected in the following aspects: the amount of waste water and waste oil produced in the production process is quite large; in printing process, more or less need to use some bad solvents, and even plasticizer (thermosetting ink may add non environmental plasticizer), such as printing water, detergency oil, white oil and so on. In practical work, the printing workers will inevitably be exposed to chemical solvents, glue, toxic crosslinking agents (catalysts), chemical dust and so on, which will have an impact on workers' health.

In the process of digital printing, only a certain amount of waste liquid will be produced in the pretreatment process of sizing and post-processing water washing. The whole pollution source is less than traditional printing, and has little effect on the environment and the health of the contacts.

In short, digital printing is widely used in printing materials, with bright colors, fine patterns, good handle and strong environmental protection. However, inkjet printing machine is expensive, consumables and maintenance costs are high, which is its drawback. Digital printing products are difficult to improve in terms of water fastness and rubbing fastness; it is difficult to develop stable white ink, resulting in printing on black and dark fabrics, and because of the restriction of inkjet printhead, it is difficult to develop ink that can print special effects. Printing sometimes needs to be pre processed and post-processed, which is more complex than traditional printing. These are the disadvantages of digital printing.

If traditional screen printing is to develop steadily in the printing industry today, we must grasp the following points: improving the environmental protection of printing ink, controlling the environmental pollution in printing production, perfecting the existing special printing effect printing, developing new printing special effects, leading the printing trend; following the 3D upsurge, developing various 3D printing effects; While maintaining the performance of washing and rubbing color fastness of printing products, we develop digital imitation of no touch and light printing effect in conventional printing, develop a wide format printing scheme, and constantly improve the printing efficiency and productivity. It is best to develop a printing pipeline platform, simplify printing equipment, reduce consumables and investment, increase the input output ratio of printing, and enhance the competitive advantage of digital printing.

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