The corrugated Paper Box and carton are the outer packagings of the product. The important role of the corrugated paper box and carton lies in the convenience of logistics transportation and protection of products. On the other hand, it is easy to identify the characteristics and related information of the interior products, and enhance the added value of the products through reasonable packaging. Therefore, the emphasis on the carton, carton process design and technical control, not only can improve the performance of product packaging, but also on product promotion can also play a good role.
Reasonable design and technical control of corrugated box and carton strength
When designing corrugated cartons and cartons, the characteristics of their use should be fully considered. This requires that the production process designers must carefully understand and master the factors related to the effects of plate design, and the influence on the printing process and product packaging. If the compressive strength of corrugated boxes and cartons is prevented from being damaged by the side effects of the printing process, if a flexographic process is used to print a large area of ​​the actual layout, the tissues absorb a large amount of ink and ink, resulting in a decrease in the compressive strength of the finished products. In addition, the printing layout lines should be avoided as far as possible in parallel with the corrugated arrangement, but should make the printing layout line and the corrugated direction arranged vertically. This can better avoid damage to the corrugated box and carton. Therefore, the cartons and color boxes that are used as product packaging should not be designed too complicated. The layout of the printing layout should be simple and clear, and the color number of the printed color should not be designed too much. For example, the color rendering effect of multiple colors may be considered. The local layout is used to create new colors by overprinting to minimize the number of prints, which can not only save expensive materials such as flexographic plates and inks, but also reduce the impact of printing on the strength of the cardboard. For the design and technical control of the carton structure, attention should be paid to the relationship between its shape and the strength of the finished product. The greatest support for cartons and color boxes should be their four corners and the sides immediately adjacent to the corners. Therefore, the supporting power of square carton and color box is relatively large. In addition, the longer the circumference of the paper container, the higher the height, the lower its corresponding compressive strength; the larger the opening area and the closer to the corner, the lower its compressive strength. Attention should be paid to the control and control of these technical details during design.
Print layout design and technical control
The use of flexographic printing of cartons and cartons should be based on the flexibility of flexographic plates and the proneness to deformation during embossing. From the technical point of view of improving the resolution of printed plates, the printed plates should be designed to avoid the design of fine lines and texts. Or pattern, so as not to appear illegitimately. The text and line layout are designed to be appropriately large, so that they have a visually pleasing sense. They are also suitable for use in packaging products that require intuitive and easy identification. In addition, in order to ensure the quality of the layout printing, avoid the appearance of stencils on the local layouts, and avoid designing solids and shades on the same color layout; on-site and outlets; on-site and fine text; on-site and fine-letter or line and fine text versions. Coexisting printing layout structure. If the customer requires the same color layout must design the above layout structure, it is appropriate to split the contents of the field and the small layout into two pieces, and use the advantages of the flexible multicolor printing unit to print the same color with two color groups. Layout. In this way, plate making and printing, on the one hand, are conducive to controlling the exposure and washing process of the printing plate, effectively avoiding the plate material scrap caused by improper plate making control, and on the other hand, can make the actual site and the fine plate layout obtain suitable respectively when printing. Ink volume, guarantee product printing quality.
Mesh layout level design
Because the flexo dot reproduction is not as good as that of the PS plate, the fine dots are difficult to reproduce in the process of plate making and printing. In particular, highlights are easily lost. Due to the effect of pressure, the soft printing plate is prone to enlarge dark spots and become paste-like. Due to the expanded distortion of outlets, the printing layout lacks a sense of hierarchy, and the quality of printing and copying will be significantly reduced. Therefore, for the printing of carton paper, the screen highlights should be designed to be no less than 4%, while the dark tone network should be controlled at about 85%. If the paper surface is rough, you should also consider increasing the number of dots in the highlight area.
Design of the number of screen lines
The design of the number of screen lines is also sensitive to the impact of carton printing quality. The lack of high gloss on the paper surface is a common feature of the carton material. If the number of screen lines is too small, it is more prone to paste and affect the clarity of printing. Therefore, the number of carton lines depends on the quality of the cardboard material. The number of screens for general flexo is controlled at about 100 lines per inch. Preprinted color corrugated cartons use high-grade coated whiteboard paper. If high-performance flexible printing equipment is used for printing, the number of plate-making screen lines can be selected from 150 lines/inch to 175 lines/inch. If an ordinary corrugated cardboard box is directly printed, the smoothness and flatness of the surface of the corrugated cardboard are considered to be poor, and the layout design is to control the cable to be less than 100 lines per inch, or even 60 lines per inch of the coarse cable.
Design of network line angle
No matter what printing technology is adopted, whether the network line angle is designed rationally also affects the printing quality of the carton products. The company used Heidelberg 4-color offset press to print corrugated box paper. The author found that the pattern pattern had an abnormal moire phenomenon when he saw the sample test. After careful observation with a magnifying glass, this was caused by the deviation of the black version of the cable angle. After the revision, the pattern level is consistent with the original. It can be seen that the layout of the network dots is only suitable for the difference in the angle between the screens of different colors, and the printing can show a pleasing and comfortable color effect. The author believes that with the rational design of the angle of the lithographic color carton, one must consider the design of the line angle according to the reflection coefficient of the ink to the light. Because of the different colors of cyan, magenta, yellow, and black in the four-color ink, the reflectance to light is also different. Among them, yellow ink has the highest reflectance to light, followed by magenta ink and cyan ink, while black ink has the darkest hue and therefore has the lowest reflectance to light, and yellow is also called weak color, while cyan, magenta, and black. It is called strong color. The more reflective the color is, the closer to white it is, and it is similar to the true color of the paper, so it is not easy to be noticeable to the naked eye. Because the pattern composed of weak color dots is not conspicuous, it is customary to arrange the yellow version at 0o or (90o) for the printing process, while the blue, black and magenta versions are designed for printing at 15o, 45o and 75o. The second is to design the network line angle according to the strength of the ink color. Since the 45o cable angle has the most comfortable and visual effect, the color of the original main color screen should be printed on the 45o cable, while the 15o and 75o are assigned to the other two. Strong colors. In addition to taking into account the nature of the ink line, but also taking into account all aspects of factors, flexible arrangement of printing color sequence, can not adopt the practice of rigidly applied. If the black layout of the manuscript is dominant, yellow, cyan, black, and magenta can be printed at 0o, 15o, 45o, and 75o, respectively, to highlight the role of the black plate. With warm colors yellow and magenta playing a dominant role in the picture, such as the main character of the warm color, the picture mainly highlights the face and skin color, the network line angle can be arranged for the yellow version 0o, Qing version 15o, magenta version 45o, In the black version 75o, this sample has a difference of 45o between the red and yellow plates, and it is not easy to produce a distinct moire phenomenon. This arrangement makes the magenta version, which dominates the warm-tone picture, perform the printing color effect at the best screen angle. At the same time, it is avoided that the magenta version is separated from yellow by 15o, and it is easy to produce visible moiré print defects in light-colored areas. For cold-tone-based screens, such as cartons with a fruity green leaf layout, the dominant color in the screen is a green-blue color, so that the yellow screen angle can be arranged as 0o, magenta, 15o, and cyan. 45o, black version 75o printing. Can also be used by the yellow version 0o, black version 15o, Qing version 45o, magenta version 75o design network cable angle. If the original screen has both human skin color and blue green, the area of ​​the yellow version can be appropriately enlarged, while the three versions of cyan, magenta, and black remain unchanged. Due to the differences between the flexographic process and the lithographic process, the flexographic process uses an anilox roller to transmit ink. If the anilox roller has a 45° reticule, the screening angle should be as low as 45° so that it can be avoided. Moire phenomenon occurs during printing. The general flexo-printed screen angles are: Y90°, M15°, K30°, and C60°. The design of the overlapping pattern network line angle should be different from the main color of the layout by 30°. For example, the carton layout for fruits and vegetables is based on the green tone screen. Therefore, the angle difference between cyan and yellow must be controlled at 30°. Better to prevent moire when printing. In order to achieve better printed visual effects, the cable screen version must be based on the characteristics of the product. Starting from the actual situation, it is best to determine whether the screen-printing system has achieved the desired quality by proofing.
Designing layouts and controlling printing distortions according to the characteristics of media
A remarkable feature of the flexographic plate is that the plate is soft and elastic. When the flexographic plate is pasted onto the cylindrical plate roller, the plate is bent along the circumference of the cylinder. This deformation causes the plate to follow the circumferential pattern of the cylinder. To expand the deformation, the thicker the plate is, the larger the deformation will be. Therefore, when designing a plate, it is necessary to fully consider this factor, such as appropriately reducing the size of the plate corresponding to the circumferential direction of the plate cylinder, so that the longitudinal size of the printed plate after printing conforms to the requirements of the original. In other words, it is necessary to consider the appropriate reduction ratio when designing a plate. Experiments have shown that the larger the diameter of the drum is, the smaller the reduction ratio is, and the thicker the plate material is, the larger the reduction rate is. Reducing rate is usually determined by the formula, that is, reduced version rate = K / R × 100%, where R is the actual printing length of the print, K is the reduction of the printing plate, is a constant related to the thickness of the flexographic plate It can also be obtained by the formula K=2πd, ie 2×3.14×printing plate thickness. R value can be obtained by the formula, that is, R = 2π × (r + b + c), where r is the plate cylinder radius, b is the thickness of the tape, c is the thickness of the plate. The production process shows that according to the formula, the reduced version of the platemaking can only be an approximate value, not an absolute value. Because of the difference in factors such as machine performance, plate hardness, elasticity, plate embossing height, printing material properties and pressure, the reduction rate will be different, such as the deformation coefficient of the rubber plate is larger than that of the resin plate. The version rate is also correspondingly large. Plate-making designers usually have to go deeper into the production site to follow up and master the more practical data for analysis before they can accumulate more and better plate-making experience. In addition, in the case of a line-shaped layout such as a bar code, if a line is designed to be balanced with the plate cylinder, the gap between the lines and the width of the lines are prone to be enlarged and affect the use effect. Therefore, for fine line layouts in which the reduction ratio is difficult to set accurately, it is preferable that the lines and the printing platen shaft are axially designed to be printed in a vertical structure so that the gaps between the lines and the widths of the lines do not suffer from deformation problems. , can better guarantee the printing quality.
Technical requirements for plate design from different materials
The material of printing cartons is not as good as high-gloss coated paper, glass cards and other high-grade materials. This factor must be taken into consideration when making plate designs. Therefore, for the paper that is easy to lose powder and lose hair, it is necessary to avoid designing a small layout that is easy to produce paste. According to the characteristics of the printed materials, the plate making process should be designed. For the more precise printing plate layout, it should be arranged along the axial direction of the roller; the poorer the paper surface glossiness, the larger dot area design should be, and the smaller the line number of the screen should be, the smaller it is. Loose paper that is prone to deformation when printing, to avoid the design of precision overprinting layout; poor quality paper, the hardness of the printing plate should be softer, so as to effectively reduce the appearance of printing defects, improve production efficiency and product quality.
From the Accuracy of Overprinting to Control the Platemaking Technology
Compared with the lithography process, the overprinting accuracy of flexographic products is worse, multi-color overprint products, according to the weaknesses of the process, try to avoid the multi-color layout of each other for precision overprint, the black text, letters, Line layout, should not be designed into a four-color layout superimposition process effect, so as not to produce a clear overprint is not allowed to malpractice. This is because the final printed color effect after the four-color layout is overprinted is approximately black. So, as long as the design is black and monochrome. For the precise overprinting layout, the edge of the light-colored printing plate should be enlarged by about 0.2 mm so that the light-colored layout outlines the slight dark-colored layout edge to avoid obvious over-whitening phenomenon due to overprinting errors. For small texts, letters, and line layouts, it is necessary to avoid designing a “concave and convex†overprint structure so as to avoid overprinting of defects. According to the characteristics of the product packaging, it is possible to design a dark color, an appropriate area of ​​the text, letters, line layout superimposed on the light-colored layout, so that its process effect is no less than the effect of overprinting process.
Design and Control of Printing Process Technology and Post-printing Decoration Process Technology
With the continuous development of the commodity economy, the use of pre-printing methods to print color cartons and cartons is becoming more and more popular. This is because the preprinted cartons and cartons are printed in vivid colors and the graphics are conspicuous, and they can be used for promotion and promotion. The role of the product. However, it should be noted that in the process of handling, packaging, and transportation of cartons and cartons, vibrations, impacts, and frictions are inevitably present, resulting in damage to the printed images and texts and affecting product quality. Based on the test and comparative analysis, we decided to make corresponding technical improvements to the production process. The practice is: use fast-fixed, wear-resistant offset printing inks to improve the ink adhesion and wear resistance. In addition, taking into account the carton in the automatic production line automatic transport, packing process, it is also easy to appear due to severe vibration, friction and fading situation, improve the post-printing finishing process of carton paper, wear-resistant glazing The glazing was performed to improve the smoothness of the noodle paper, effectively preventing the occurrence of adverse conditions such as discoloration, and satisfying the use requirements of the customer.
Through the technical control and control of corrugated boxes and carton design links, according to the characteristics of product packaging, from prepress, printing to postpress technology, through careful design and reasonable control, better product quality, prevent The production of print quality problems and better reduction of production costs will undoubtedly have a good promotion effect.
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