Brief analysis on the misprint of corrugated
Paper Box At present, as packaging and printing are in the forefront of the domestic printing and packaging transformation, a large number of old and new printing companies are competing to carry out packaging material printing represented by corrugated printed packaging, but due to insufficient understanding of materials, many processes are prone to appear in the printing process Most of these technical problems are caused by the misunderstanding of production workers. The misunderstandings that are easy to occur are analyzed as follows. One of the misunderstandings: the selection of plates is blind Many plate-making companies do not consider the actual conditions of the printing plant, such as the type of printing machine, the thickness of the platen tape, the type of ink used, etc., and blindly follow the crowd. Taking the printing plate used for corrugated boxes as an example, many customers only know DuPont's very famous TDR type plate material. TDR is a widely used corrugated paper printing plate with excellent plate-making performance, but its resolution is not as high as a batch of thin plates such as EXL / UXL. When printing E-shaped corrugations and images up to 120 lines / inch, thin plates such as EXL / UXL should be used, and sponge padding should be used to obtain high resolution. At the same time, with the increase of the hardness of the plate, it can also reduce the expansion of the dots, so that the printed products can achieve excellent results. Misunderstanding 2: Unreasonable pre-press system configuration Because the special software for flexo printing is relatively expensive and cannot be afforded by ordinary small and medium-sized plate-making companies, there are currently only a few overseas companies that can afford it, and the vast majority of plate-making manufacturers have made localizations that are tailored to local conditions. Generally speaking, small-scale plate-making factories mostly use platform scanners and digital cameras as input devices, modify the PC or Apple G3 used in computers, and add phototypesetting and filming machines as output equipment. Due to the limitation of the plate-making scale, many domestic manufacturers copied the configuration of offset printing plates, and even used lagging technologies such as printout and photography, which made the domestic
Corrugated Box flexo printing technology always at a low level, just as a hand-engraved rubber plate Has not yet entered the era of color corrugated box printing. Compared with foreign counterparts, we are nearly 10-15 years behind. Misunderstanding 3: Using offset printing film as the final output film It is true that offset printing film has a series of advantages such as convenient procurement, economy, and timely delivery, and the process conditions are relatively mature. However, offset film has a fatal weakness: the surface is too smooth. The photosensitive resin flexographic plate will release a certain amount of oxygen during the photopolymerization reaction (physicochemical mechanism belongs to the patent scope and will not be disclosed), and only the matte film can guide these oxygen smoothly, so that the film and the plate remain Should contact, transfer images accurately. On the contrary, the surface of the offset film is smooth, and the oxygen cannot be smoothly led out, resulting in a larger gap between the film and the plate, causing image distortion, thickening of the text, and blurring. Some plate-making operators adopt the method of spreading talcum powder to alleviate these problems to a certain extent, but at the same time, it also causes a decrease in light transmittance and increases the cloudiness of the film. Misunderstanding 4: The design of the plate-making machine is defective Some domestic plate-making machine manufacturers, in order to compete in price, are crudely manufactured at a low price. The typical method is to copy the circuit design of the fluorescent lamp and use low-cost domestic ordinary ultraviolet lamps. Since the circuit of the fluorescent lamp is directly started by the starter, the flicker generated after the lamp is started will inevitably cause the back exposure requirements of the plates with high back exposure requirements such as EXL / TDR and short back exposure time, resulting in non-uniform back exposure. The photosensitivity is uneven. After such a plate material passes through the plate washing, a substrate with a wavy surface will be obtained. The correct approach is to select high-quality ultraviolet light sources, such as PH ILIPS company's VA-R series lamps with high-quality ballasts and starters, and add about 5 volts of filament voltage across the filament (very important). In this way, the filament can be kept in a red hot state. During the exposure, only the main circuit power supply needs to be turned on, and the lamp can be instantaneously started, and the state of uniform exposure can be achieved. The radiant energy of PH ILIPS lamps using this connection can reach more than 160m w / cm 2, while the ordinary lamp is only 40m w / cm 2, the radiant energy difference is 4 times, which means that under the same exposure The efficiency difference is 4 times. Myth # 5: Misunderstanding exposure tolerance According to the international FTA recognized standards, the following requirements are made for exposure latitude: Tolerance = cut-off time-formation time 1. For corrugated box printing plates (above 2.84mm), it means that the depth of the negative line from 0.8mm wide to 0. 8mm wide from the exposure time of 3% dots on the 34L / cm printing plate. When lmm. 2 For a thin plate (below 2.84mm), it means that the depth of the negative line from 0.8mm wide to 0. 8mm wide is reduced from the exposure time of 2% dot formation on the 48L / cm printing plate. lmm deep. The greater the tolerance, the less sensitive the changes in exposure time when the plate is. Some inferior plate materials are filled with negative lines before the dots are formed, and their exposure tolerance is negative, that is, the dots and the negative lines cannot be printed on the same printing plate at the same time. Some platemakers excessively require the depth of the plate relief to make the substrate too thin, making the main exposure time too long and losing the depth of the negative line. Misunderstanding 6: Do not pay attention to keeping the plate-making solvent fresh Every time the plate is washed, fresh plate-washing solvent should be added in an appropriate amount to keep the photosensitive resin component in the solvent not too much. Never use undistilled old solvent as fresh solvent in the fresh solvent pipeline. Otherwise, it seems to save costs, but comprehensive consideration of downtime due to printing plate problems and waste of paper and damage to the accelerated plate-making machine is really worth the loss. There was an example of a plate-making machine worth more than 100,000 US dollars. The lack of fresh solvent for a long time caused many problems such as caking of the brush, clogging of the spray, and poor circulation in the machine. It almost caused the plate-making machine to be scrapped. The French engineers who came to the original factory to repair it only avoided more losses. Therefore, ensuring a certain amount of fresh solvent supply can not only reduce the stickiness and swelling of the plate material, but also increase the speed of the plate washing, but also help to extend the life of the plate washing machine and improve the quality of the plate washing. About Liyang : Liyang Paper Products Co., ltd is a factory and trade company located in Dongguan, China. Specialized in producing gift paper packaging, such as
Gift Box,paper box,
Paper Bag,shipping box, mailer box,corrugated box,,etc. Custom made base on your design is welcome, feel free to contact Liyang printing with your full details. www.dgliyang.en.alibaba.com │ www.liyangprinting.com
June 12, 2020
