In the past, the main function of corrugated boxes was as transportation packaging, and its surface printing was also very simple. The reasons are as follows: First, carton manufacturers and users do not pay attention to the packaging design of corrugated cartons, and only use cartons as tools to protect and contain products; secondly, the surface flatness of corrugated cartons is relatively poor, and it is difficult to print beautiful patterns; again , The previous printing plates were all hand-engraved plates, which could not reproduce the fine lines and dots at all. Of course, there are also reasons such as insufficient number of printing units, which have restricted the rapid development of carton printing.
In recent years, with the rapid economic development and increasing exchanges with foreign countries, people have become more aware of the importance of packaging and decoration, especially the influx of international supermarkets such as Wal-Mart and Carrefour, as well as the increasing number of domestic supermarkets. People have changed their traditional shopping habits, and at the same time, the sales function of corrugated boxes has become increasingly prominent. Users have begun to pay more and more attention to cartons, the outermost packaging that displays products and company images. At the same time, the widespread application of flexographic plates (photosensitive resin plates) and the rise of flexographic pre-press technology have also given strong support to carton printing.
In the field of packaging design, the past color packaging or exquisite packaging design is mostly realized by offset printing and gravure printing. Offset printing and gravure printing are mature printing methods, and there are still many printing suitability that require designers to pay attention to when designing packaging. Flexo printing is a new printing method. If you want to truly reproduce the designer’s packaging design, you need more attention from the designer. Further understanding of the characteristics of flexo printing. When designing the direct flexo printing of corrugated boxes, the designer must pay attention to the following points.
1. Clearly express the color number of creativity
The world is full of colorful colors, especially the designer’s eyes, who are good at discovering beautiful colors and organizing them together organically to create all kinds of elegant, bold, warm, or strong visual impact. work. As a packaging design, the ultimate goal is to achieve its own creative effects after printing, and to achieve industrial production. Therefore, for the packaging design of corrugated box direct flexo printing, in terms of color application, you must first understand that your creativity is realized on a several-color printing machine, and make it clear that your creativity is expressed in several colors. The number of domestic corrugated box flexographic printing presses generally ranges from 2, 3, 4, and 6. Before confirming the use of several colors, on the one hand, the number of color groups of the printer must be considered, and on the other hand, whether to use white ink and varnish in the process, so as to finally determine the number of colors that can be used to express creativity.
Of course, under the premise of fully expressing the design creativity, the number of printing colors should be reduced as much as possible, which is beneficial to the printing operation, quality control, and cost control during mass production.
In addition, many manufacturers hope to use as many spot colors as possible to achieve the uniform color of each batch of products and play a certain anti-counterfeiting effect. Therefore, in addition to the traditional CMYK4 colors, spot color inks are used in the design of its packaging. However, in actual operation, due to the limitation of the printing machine, the manuscript that needs to be printed on the four-color machine cannot be expressed in 4 colors in the color separation. In the end, I had to communicate with the designer to combine the similar colors into one color. Or make changes to the designer’s work.
Since flexo printing transfers ink through the anilox roller, the number of lines of the anilox roller determines the amount of ink transfer and the fineness of printing. Generally, a high-line count anilox roller is used for screen adjustment to make the dot printing clear; while a low-line count anilox roller is used for the solid version to achieve color saturation. When there are both screen tone image and solid ground in a color, and it is visually prominent, the color is generally divided into screen tone and solid plate to make the printing operation easier. Therefore, when considering the overall color number in the design process, do not neglect this feature of color separation in flexo printing.
In addition, this situation is often encountered in practice, that is: many corrugated box printers are three-color machines and cannot achieve normal four-color printing. Therefore, in the process of colorizing corrugated box watermarks, three colors are often used. Reproduce four-color manuscripts. The following two practical situations need to be considered when using three-color overprinting to produce black:
(1) The color cast of the ink causes the three-color overprint to produce non-standard black;
(2) Three-color overprinting will make the ink layer too thick, which will affect the printing quality and effect.
In view of the above two situations, when dealing with packaging products printed with three-color machines, designers need to understand the ink situation. In some printing plants, the color cast of the ink used should be properly considered to reduce the color intensity of the biased color. Some manuscripts may not necessarily remove the black version. For example, the green version can be removed for the reproduction of food, and the red version can be removed for the reproduction of trees. In this way, the style and level of the manuscript can be maintained to the utmost extent. If the number of colors is taken into account in the design, the above difficulties will not be encountered before mass production. For example, when we were dealing with the design of Tsingtao Beer cartons, we considered that it would be realized by a three-color printing machine, so we successfully realized the watermark color printing process of corrugated cartons and promoted it in the market.
2. Pay attention to the level of application
Due to the different tastes of the designers and the different characteristics of the products, there are differences in the style of packaging design. Some pursue simplicity and clarity, and some pursue rich levels. But if his design works are realized by flexographic printing, the use of levels in the design must attract the attention of the designer.
Since the flexographic version is letterpress and the material has high elasticity and is easy to deform, the dots increase more severely after being pressed, and during the plate making process, 1% or 2% of the small dots are easily lost during the plate washing process. It can’t be reproduced very well in the medium, 3% of the dots will expand to about 10% after printing. It is impossible to achieve a gradual change from 100% to 0% or a very soft gradation effect, so the high light and dark colors that flexographic products can express The gradation area of the tone is relatively small, and the highlights of the printed product can only reproduce 8% to 10% of the dots. Therefore, less than 8% of the dots in the design cannot be displayed in actual printing. For example, the use of gradient colors, if the dots are gradual to 0%, there will be obvious boundaries or seals at the small dots or at the corners, which will affect the image of the packaging. Although each manufacturer has its own way to overcome or solve this problem, in any case, flexo printing cannot be comparable to offset printing. Only by considering this characteristic of flexographic plate when designing, can you realize your design after printing.
For another example, if the edge of the image is faded, if it is faded to the absolute net, the aforementioned problems will also occur, which requires designers to consider avoiding such problems when designing packaging.
In addition, as mentioned earlier, the number of anilox roller lines used for flexographic ink transfer is different for the screen adjustment plate and the solid plate. Large-area solids are connected with partial gradations, and printing is very difficult. Especially for manuscripts with darker colors on the ground, the screen tone part is taken care of, and the field is not printed or the color is light; when the field is taken care of, the screen tone part is blurred and dirty. Although it can sometimes be solved by selecting an anilox roll with a moderate number of lines and reducing the number of screen lines in the screen adjustment part, it does not match the designer’s original intention in any case.
It is worth mentioning that in packaging design, gold and silver ink are often used to enrich packaging design effects and improve packaging quality. When using gold and silver inks, if the pattern contains mesh tones, it is best to leave more space in the highlights and shadows, and the dots in the highlights should be more than 20%, because the dots of this type of ink printing are easy to paste.
Three, consider printing registration
Like offset printing and gravure printing, flexographic printing also involves overprinting issues. In flexo packaging design, on the one hand, we must pursue the exquisite pattern, on the other hand, we must also consider the difficulty of printing. For example, for small characters and patterns, if they are to be represented by overprinting, it is difficult to guarantee the accuracy of overprinting, which will inevitably lead to an increase in the rejection rate or unsightly printed patterns. This problem is usually solved by trapping. The trapping of corrugated boxes is usually 0.5~1mm, and sometimes it may be slightly smaller for different printing machines. If the printing of characters and patterns is difficult under such a large trap, it must be adjusted accordingly. Especially for the overprinting of complementary colors, there will be obvious black borders at the junction of the two colors, which affects the beauty of the packaging. Relatively speaking, the overprinting of dark and light colors will be much better. In addition, a set of characters or color blocks are overprinted by multiple units, which also increases the printing difficulty. Since most of the flexo printing machines used in China are driven by gears, the regular color block or line arrangement of one dark and one light or multiple colors in the packaging design will also cause difficulties in printing.
The embossed pattern on the flexographic plate is formed by brushing off the unexposed parts with a washing liquid and a brush, so the flexographic plate has requirements for the smallest characters and the smallest line sizes. For corrugated box printing, we suggest that the thinnest line should not be less than 0.5mm. If it is an isolated line, it should be widened appropriately. As for the text, it is better to refer to the above-mentioned data for the stroke thickness. Because the stroke structure of bold font and Song font is different, it is difficult to set the minimum font size uniformly. Pay special attention when using the “Da Song” font, because the thickness of the horizontal and vertical lines are too different.
In the use of barcodes, since the flexographic plate is easily deformed under pressure during the printing process, the plate is flatly attached to the round cylinder and needs to be deformed, so attention must be paid to the handling of the barcode. For different printing machines and different bar code sizes, each bar code must be reduced in advance before plate making to ensure that it can be detected after printing. Of course, this reduction is done by the plate maker. Here we should remind designers to pay attention to the direction and size of the barcode. The size of the barcode should refer to the standard, and the direction of the barcode should be as consistent as possible with the printing direction.
Fourth, pay attention to the typographic effect of packaging design
In packaging design, the general designer only pays attention to the finished product effect and plane effect of the packaging, and seldom pays attention to the typesetting effect of the packaging. Printing is a mass production process. It is necessary to arrange the single images of the packaging according to the width of the printing press and the circumference of the plate roller. Therefore, the layout effect must be considered when designing. Especially when a single pattern needs to be arranged repeatedly, the color of the intersecting position should be the same or the connected pattern design should be continuous to avoid the partial pattern on a package from appearing on the layout in isolation after printing due to die-cutting deviation. On the other packaging, the finished product packaging is unsightly. Avoid this type of layout as much as possible when designing.
The typesetting issues mentioned above are all small-size packaging. In fact, many of the corrugated carton packaging are large-size, such as refrigerators, displays, etc. Packaging, when designing these large packages, the film output and plate size must be considered. limitation. At present, the maximum size of domestic flexographic plates cannot exceed 2000mm×1320mm, and the film output is mostly within 1100mm×800mm. When designing large-size packaging, these process characteristics must be taken into consideration. It is best not to design patterns that exceed these sizes into continuous patterns or overall patterns. Once designed in this way, the plates must be spliced before printing. No matter how careful the splicing is, there will be obvious interfaces on the pattern after printing, which greatly affects the exquisiteness of the packaging. When designing, only considering the convenience of disassembly of large-size packaging printing plates can the printed products conform to the designer’s creativity.
Five, try to use vector software when designing
At present, most designers use computers as tools to show their creativity. Design software has vector forms, such as Illustrator, Freehand, CorelDRAW, etc., and pixel forms, such as Photoshop, Panit, etc.. Don’t use all of them in the design process. Use Photoshop and other pixel-based software to produce. Photoshop is best used to process images or produce some special effects. Other lines, text, and color blocks are best to be produced with vector software such as Illustrator, Freehand, etc., so that the manuscript is sent to the plate-making company. Only the plate-making company can make some adjustments to the design draft according to the characteristics of flexographic printing more conveniently and quickly, such as trapping, lowering the curve, etc., to achieve the effect of convenient printing. When a designer delivers his design work to a printing manufacturer or plate maker in the form of electronic data, it is best to convert all the text in the design draft into a path before data storage, so as to reduce the recipient’s font change due to incomplete fonts and other reasons. . If there are too many texts to be changed or the texts are not converted into paths, the corresponding font library and the design manuscript should be sent to the data recipient.
In a word, in order to print good printing results through corrugated box direct flexographic printing technology, the characteristics of corrugated box flexographic printing technology must be fully considered from the beginning of the manuscript design, and this also requires the cooperation of designers, plate manufacturers, printing manufacturers, and end users. Consulted hard.