The main application of laser technology in flexographic printing

Laser technology, which is known as one of the four great inventions of mankind in the 20th century with computers, atomic energy, and semiconductors, has now played a major role in the field of printing. Flexo printing has been rapidly developed due to the application of laser technology. . Laser is an artificial light source with high frequency, high brightness, strong directionality and good monochromaticity. It is one of the most active science and technology developed in the 1960s. The current laser technology has become a popular and practical new technology. In recent years, it has also achieved key developments. For example, the output light wavelength can be selected according to needs; and a high-efficiency ultraviolet laser is invented. All these have created extremely favorable conditions for scientific research and applications.

Laser promotes revolution in flexo platemaking technology

The high-tech of flexo platemaking is laser direct plate making (also known as computer-to-plate or digital direct-to-plate, or CTP). The core technology of the technology originates from the laser technology that emerged in the 1960s and is now widely used. Computer direct plate making improves the speed of plate making, improves plate quality and printing quality, and is conducive to environmental protection. Using CTP technology, not only can be printed on paper, but also printed on a variety of plastic film and composite film, metal foil, wood, glass, ceramics, textiles and other substrates.

Due to the fact that the flexographic plate has a certain thickness, it is much more difficult to obtain three-dimensional dots by exposing the digital information directly to high-speed lasers on the plate material. However, it can avoid all kinds of unfavorable factors in the traditional platemaking method. For example, the use of film processing requires multiple image processing, which is not only poor in stability but also high in cost. In addition, the temperature and humidity have a certain impact on the film, and sometimes have to guard against scratches and other scratches of the film; when the film and the plate are closely exposed, the image quality may be damaged due to light diffusion or poor adhesion. Cannot reproduce subtle tones;

Because the smaller dots are not easily printed, they can only be printed with coarse screen lines. The introduction of a flexographic platesetter directly exposes the image to the flexographic plate, overcoming the above-mentioned disadvantages caused by the use of the film. The flexographic plate used for direct plate making is different from the ordinary plate, and its surface A layer of etched layer, a synthetic carbon film, is applied. This synthetic carbon film also avoids dust particles.

When the laser scans, the overlay at the spot is melted to evaporate without leaving any traces, which is equivalent to leaving an extremely clear picture on the surface, and then the back of the flexo is still exposed as usual. (At this time, the exposure time determines the thickness of the plate). The main exposure (the light source passes through the opening of the synthetic film that has been eroded and the direct exposure of the photopolymer underneath it, so that there is no scattering or diffuse reflection, so the edges of the dots are smoother and the digital plate material is The exposure time is longer and it does not cause the dot shape to blur. Finally, the etching process is performed.

Reprinted from: World Science and Technology Report