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Development Of Flexo Platemaking Process
- May 28, 2018 -

In recent years, the wind of green environmental protection has been blowing. In November 2010, the emission standards for packaging and printing VOCs in Guangdong were formally implemented, and the printing industry was included in the scope of air pollution prevention and control. On January 1, 2015, the new “Environmental Protection Law” with “the strictest history” was put into effect, providing for a system of penalties on a daily basis, and the total amount of fines was not capped. On October 1, 2015, Beijing began to levy VOC charges in 17 industries, including furniture manufacturing, packaging and printing, petrochemicals, automobile manufacturing, and electronics. As of June 2017, pilot sewage charges for VOCs have been expanded to 19 provinces and cities across the country, namely Beijing, Shanghai, Jiangsu, Anhui, Hunan, Sichuan, Tianjin, Liaoning, Zhejiang, Hebei, Shandong, Shanxi, Hainan and Hubei. Fujian, Jiangxi, Yunnan, Guangxi, and Henan.

Flexographic inks use less impact on the environment and human health, VOCs emission less, and its green image has long been recognized in the printing industry. In addition, the government attaches great importance to environmental protection and has invested heavily in environmental monitoring. Flexo India's development is in the right moments (green environmental protection requirements), geography (China's huge packaging and printing market) and Renhe (common in policy support and flexo printing). The great period of hard work has achieved rapid development in recent years.

The phrase “three-point printing, seven points before printing” is widely circulated in the industry and applies equally to flexographic printing. Separation design and plate making will directly affect the quality and effect of printed products. Thanks to the broad application prospects of flexographic printing, flexographic platemaking technology has also made considerable progress.

Development Process of Flexo Platemaking Process

In 1973, DuPont invented a flexible photosensitive resin plate, together with the use of metal-ceramic anilox rollers, which led to a qualitative leap in the development of flexographic printing. In 1995, DuPont took the lead in the introduction of a flexographic platemaking technology. The quality of the printing plate shortened the preparation time before printing. After the world's first digital flexographic imaging equipment CDI was displayed on Drupa 1995, the flexographic plate making became one of the most closely watched technologies in the flexographic printing field. 1997 In 2004, BASF and other four companies jointly launched the flexo plate making technology to further improve the plate making technology. In 2000, DuPont introduced a flexible version of the thermal plate making technology, shortening the flexographic plate making time. At the same time, seamless sleeve plate making technology was introduced; in 2008, DuPont officially launched flat-top dot-spot technology.

Washed plate technology

As early as the 1980s, DuPont introduced a flexible plate based on water washing technology, but found two limitations during its use: First, because the use of water as a solvent to clean the plate, washing the flexographic printing plate for flexo ink Tolerance is extremely low, and it is not suitable for ink printing; Second, the discharge of waste water from water-washed printing plates still exceeds the standard. According to the discharge report of a certain washable plate on the market, total organic carbon TOC, total phosphorus TP, chemical oxygen demand COD, biochemical oxygen demand BOD, total nitrogen TN were all exceeded, among which the most serious COD exceeded the standard by 78 times.

Thermal plate technology

The biggest advantage of the thermal technology is that it does not use solvents to clean the plates. It neither has to worry about the potential safety hazards of solvent use and recycling, nor environmental problems, nor does it have the time consuming problem of drying. The printing plate does not swell and then recover. Therefore, the plate making speed is high and the plate produced has good stability.

From the point of view of plate-making equipment input, the use of solvent plate-making technology requires several processes such as laser plate-making, exposure, development and rinsing, drying and post-exposure. The equipment involved in this process includes: laser plate-making machine, exposure machine, Plate washer, drying equipment. In addition, solvent recovery devices and exhaust gas purification equipment for VOCs are also needed. The use of thermal plate making technology, only need laser engraving machine, exposure machine and thermal platesetter to complete the plate.

Flat-top dot technology

After long-term use of the laser version of the Dome outlet, people gradually realized that the flexo printing made by the traditional film has the advantage of high resistance to printing. If they can combine the advantages of the two to develop new technologies, they can break through the bottleneck of dome outlets. . Flat-top dot-spot technology is developed to address these issues.

The main exposure of the traditional laser plate was completed in the air, and the presence of oxygen caused the dot on the black film to fail to reproduce 1:1. By removing or controlling the influence of oxygen, a flat top dot formed by widening the shoulders of the net points has better durability and stability and can achieve more stable printing effects.

In the area of labels, flat-top outlets have one more strength: lightening of ink bars. Although the use of flat-top dots does not completely eliminate the ink bars, in the case of using the same printing mechanical structure, the ink bars formed by the flat-top dots in printing are significantly superior to other dots. Especially when the equipment is old and the mechanical vibration is severe, the printing quality of the flat-top outlets is more stable and less affected. For substrates with poor smoothness, flat-top dots also have better print latitude.

Flat-top dot-plating technology can be divided into the following categories according to the characteristics: coating type, nitrogen-filled type, and LED type.

Kodak and Medtech use a stencil-based platemaking technology that blocks the participation of oxygen in the main exposure process by laminating the surface of the flexographic plate to form a flat top dot.

Kodak has developed a unique film with very small backscattering of the UVA light source by virtue of its profound film technology and has applied a composite device to attach the film to the surface of a Kodak flexographic printing plate with a unique adhesive layer, which is then subject to the main exposure. Flat top outlets.

DuPont's flat-top dot plate making technology adopts the method of nitrogen filling. By installing a transparent glass cover on the exposure platform, it is filled with nitrogen gas before the main exposure to drive off the original oxygen to form a flat top dot.

The LED flat-top dot plate making technology uses a high-energy LED UVA light source to allow the flexible resin monomers to complete cross-linking in a relatively short period of time, thereby reducing oxygen participation in the main exposure process and forming a flat-top dot. Flint and Esko are suppliers of this technology. The energy output of LED UVA light source is uniform and stable, and its service life is much higher than that of ordinary UVA light sources. The main exposure parameters can be adjusted digitally to obtain the required dot shape. This advantage is not available in other flat-top dot dot plate making technologies. The only drawback is the high cost of equipment investment in the early stage.

Comes with flat-top dot media

With the promotion of device-based flat-top network technology, the bottleneck of such technologies gradually emerged. The biggest problem faced by customers in the use process is the balance of comprehensive cost, quality and efficiency. If you use a plate with its own flat-top screen, it not only solves the problem of investment in equipment purchases, but at the same time, in combination with multi-layer technology, you can add a layer of matte resin to the surface of the plate that has its own flat-top screen. To effectively improve the ink transfer rate.

In 2015, DuPont introduced the flat-top digital flexo-Easy series flat-top dot flexo plate. The new resin formulation plate maintains the consistently high resolution of the digital flexo, while at the same time providing the advantages of traditional flexographic plates. You don't need special screening procedures, nor do you need to use special platemaking equipment to get the best performance printing plate.

Based on flat-top dot technology, flexographic minimum independence points and field uniformity, color gamut, and high-light levels are significantly improved.

Medtech flat-top dot digital flexo plate has a 1:1 plate image forming capability, which eliminates the BUMP process that must be used before, and removes BUMP to achieve the expected print color gamut and better small dot reproducibility. In addition, the plate itself is a low-viscosity plate material, and it is very suitable for printing orders with high requirements for printing plates with high printing durability.

Recalling the development of flexo platemaking technology, flexo printing was promoted by the use of plates and other related technologies, and has made amazing progress in the past 20 years. With the rapid improvement of flexographic printing quality and production efficiency and the gradual reduction of comprehensive costs, flexo printing in China will surely usher in a new upsurge under the increasingly stringent environmental protection policies.

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