The quality of carton printing plate is the key to directly affect the printing quality of carton. If the quality of related links is grasped, the printing quality can be improved, the printing plate life can be prolonged, the printing plate loss can be reduced and the production cost can be reduced. In the production of corrugated box printing, most of the carton printing plate commonly used by most carton factories are rubber plate and flexographic resin plate. Although the rubber plate is cheaper and more frequently used than flexographic resin plate, because of its poor printing accuracy and low efficiency, it is necessary to use light sensitive resin plate to complete the printing process in complex patterns, fine text (such as bar code, screen text map, and small font)) and large-area full plate solid bottom printing. Of course, flexographic resin plate also has its disadvantages. The price of flexographic resin plate is higher than that of manual engraving rubber plate and laser engraving rubber plate. Therefore, it is particularly important to find ways to improve the printing resistance of flexo printing plate and extend the service life of flexo resin plate with the best use method. Only by controlling the quality of the flexographic resin plate, mastering its use method, and controlling every link related to the printing plate, can the printing quality be effectively controlled and the exquisite carton can be produced. Control of quality factors related to flexo resin plate Corrugated board is a kind of poor quality paper-based printing materials because of its surface roughness, roughness, large thickness error (such as A-type corrugated board and C-type corrugated board, the thickness error is generally 0.5mm, or even higher), board warping, printing surface powder dropping, scuffing, sand particles in the paper, rough calcium carbonate filler copied in the box paper, etc. In the printing process, these defects can easily cause the printing plate to paste, crush, even wear or damage the flexographic resin plate, and shorten the service life of the printing plate. Therefore, in the production process of corrugated board, we strictly control the raw paper into the factory and the paperboard production process. Selection and arrangement of flexographic resin plate the flexographic resin plate for corrugated box printing is generally made of plates with thickness of 3mm ~ 7mm and shore hardness of 25 ~ 30. In order to overcome the surface roughness and roughness of corrugated board, it is necessary to put forward higher requirements for flexographic resin plate, which requires that the printing plate should be wear-resistant, strong impact resistance, moderate hardness, good resilience after compression, uniform inking and uniform thickness. According to the pattern, text, line size and corrugated board material, the layout design, hardness requirements and production method of flexo printing plate are arranged accordingly. When the quality of corrugated board is poor and the color of full plate solid bottom is printed, the thicker and softer flexographic plate is selected; when the quality of corrugated board is good, and when printing fine patterns, small characters and screen printing, flexographic resin plate with high hardness and low thickness is selected. When the resin plate is pasted onto the polyester film with double-sided adhesive tape and water-free adhesive tape, if it is found that the double-sided pressure-sensitive adhesive tape and the water-free adhesive tape are not strong, they must not be used. Because the anti resin plate in the case of not glued, can not withstand the pressure and impact of printing, resulting in the plate after the spring, will cause the plate crush or loss. It is recommended to use silicon defoamer instead of hydrocarbon defoamer for defoamer in water and ink, because hydrocarbon defoamer will cause the flexo resin plate to swell (n-butanol used for washing plate after flexographic plate exposure is hydrocarbon), make the plate crack and accelerate the damage of printing plate.Printing content design flexographic resin plate is not like PS plate, its plate thickness and substrate material thickness is much larger than offset printing, so in the design of thin lines, small text and patterns with dot, it is not suitable to arrange on the same page with a large area of full page. It is necessary to increase the printing pressure for the full plate solid bottom to be printed clearly, and to increase the printing pressure for the fine lines, small characters and patterns with dots, it is easy to cause the printing plate deformation of the thin lines, small characters and patterns with dots during printing, which will cause the printing of fine lines, small characters and dot patterns blurred and unclear after the plate is used for a period of time, and in serious cases, it will wear quickly Or press the plate, resulting in the printed products, appear broken lines, font strokes off, dot loss and other quality problems. If you must design in a printing plate, then the full version of the field and fine lines, small text, with dot pattern can not be used the same exposure time for exposure. For thin lines, small text, with dot pattern of the plate, with extended exposure time to improve the hardness and printing resistance. Process quality control flexographic resin plate making flexographic resin plate exposure control is the key. Different exposure time will make the hardness, corrosion depth and elasticity of flexible resin plate have great difference. If the exposure time is too long and over exposure, the image and text on the plate will be lost or washed out, and the plate will also deform, harden and become brittle. If the exposure time is too short, that is, under exposure, the photosensitive layer on the plate surface will be washed off when the plate is washed. In order to avoid underexposure, especially large area solid plate and negative printing plate, we must choose the best exposure time to ensure that the resin plate reaction is sufficient. Typesetting method carton printing generally has a lot of color plate, the plate can not be cut too scattered, it is best to make the same color printing plate as a whole. To avoid the bulk and small version of the paste should be careful, otherwise in the production process due to the small pieces of printing plate paste is not firm, in the printing process caused damage and loss. In addition, when pasting, maintaining and replacing small pieces or fine patterns and characters, do not pull hard to prevent damage and tear of the printing plate. The printing plate should be pasted smoothly and the edge of the printing plate must be sealed firmly with water-free adhesive paper. If the printing plate is not in close contact with the surface of the printing roller, the printing plate will be tilted upward, and the warped part is easy to seep into the ink and then pop off, resulting in the damaged or lost plate in the printing process. In the printing process, due to the difference of the production speed of the corrugated board line and the heating area and heating time of the base paper on each preheater, the moisture content, hardness, flatness and thickness of the corrugated board produced will be different. This is more common in the production process, so in the printing process, it is necessary to adjust the relevant gap of the printing machine at any time to eliminate the influence of paperboard problems on the printing quality, and ensure the uniform ink color of the printed products. Maintenance of flexographic resin plate in order to reduce the friction of dirt on the resin plate and reduce the wear rate, the resin plate after printing should be dipped in water with a soft brush or a soft cotton yarn head, and the paper scraps, dust, debris, sand particles and ink residue on the printing plate should be thoroughly cleaned until the printing plate is washed out of its original color. If the dirt is not cleaned, it is not easy to remove after they are dried up. In the next printing, it will cause paste or be pressed into the flexographic resin plate, resulting in local damage of the plate and affecting the use. In addition, in the process of printing and after the completion of product printing, it is necessary to pay attention to whether the edge of the printing plate is warped, small words fall off, the adhesive tape falls off, and the water-free adhesive paper on the sealing edge is damaged. In case of the above situation, remedial measures shall be taken immediately to eliminate the problems, so as to ensure that the printing plate is in good condition during the next use. The adjustment of the gap between the rollers of the printing machine mainly includes the adjustment of the gap between the feeding roller and the bridge roller, between the printing roller and the printing roller, especially between the printing roller and the printing roller. This gap includes the thickness of paperboard + sheet base (0.1 mm) + the thickness of double-sided adhesive tape + the thickness of resin plate - 0.3 mm + the thickness of liner sponge. When adjusting the parallelism of inking roller, printing roller and embossing roller, it is necessary to ensure that both ends of each roller are parallel and consistent, which can provide a powerful guarantee for the uniform inking of each printing plate, and protect the fine characters and small dots from abrasion, so as to prolong the service life of flexo printing plate.Pressure adjustment the printing pressure here refers to the pressure between the inking roller and the printing plate, and between the printing plate and the corrugated board in the printing process. If the pressure between them is too large, there will be sliding friction between the printing plate and the anilox roller after being compressed, which will cause the plate to wear. In addition, the external printing plate will be compressed and deformed due to excessive pressure, resulting in accelerated wear at the edge of the plate, plate deformation, cracking, plate dropping, and the occurrence of wild ink and other faults on the printed matter. In fact, adjust the gap and parallelism between the rollers to control the printing pressure. A good press can make the plate in an ideal state of pressure for a long time and prolong the service life of the plate. In addition, under the polyester film attached to the printing plate, a layer of cushion sponge can absorb part of the printing pressure, which is also a good method to adjust the printing plate pressure. Speed control The production speed of corrugated board should be uniform during printing. If the machine speed is too fast or too fast (especially for the high printing slotting machine with more than 120 pieces / min), the resin plate and the inking roller, the resin plate and the corrugated board will have a greater impact, and the printing plate will hit the roller and jump, especially in the case of uneven corrugated board, the jump of the relevant roller will be more obvious This leads to the speed difference between the printing plate and the inking roller and corrugated board, increases the friction force on the resin plate, and speeds up the edge wear of characters and patterns parallel to the roller direction on the printing plate, and even is damaged by impact. Storage of printing plate. The original plate of the resin plate of flexographic printing which has not been made must be kept away from light. Otherwise, after being exposed to sunlight and ultraviolet light, the photosensitive material of flexographic plate will be polymerized seriously, resulting in the scrapping of the plate material, or the pattern, text and line will be washed out or the concave and convex depth will be insufficient. In addition, do not put on the wet ground and organic chemical solvents, in case of damage to the resin version. Pay attention to the storage of prepared and used plates. When stacking up and down between plates, the number of stacked plates should not be too much. Too much will make the bottom plate in a state of pressure for a long time. Especially, the printing plate with uneven stacking will be damaged and scrapped. Pay attention to the quality of each link related to flexographic printing plate and study the relationship between them. For example, for small batch, multi specification and the same type of packaging carton printing plate, when the content is the same, we can adopt the method of sharing a set of printing plate, only changing different parts, and so on, and formulate corresponding measures, so as to ensure the printing quality, reduce the number of duplicate plates and improve the utilization of printing plates It can reduce the number of labor, improve the efficiency of production, reduce the related expenses and reduce the production cost.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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