Color has a strong visual appeal and expressive force on the product packaging. With the increase in consumer demand for fine-grained packaging, high-grade color offset printing has begun to be adopted in large quantities, but due to the domestic packaging and printing enterprises in the process level There is a big difference, resulting in a large difference in the printing color of the same packaging product, especially large-format offset printing products, which seriously affect the quality of the product packaging. The most prominent quality issue affecting the appearance of product packaging is the color deviation problem. At present, the status quo of large-format offset printing products is not optimistic. After investigating the supply situation of the color boxes of a certain beer company in Qingdao, the same supplier, the same batch of DE> 1.5; the same supplier, different batches of DE> 2.0; For the same species and different suppliers, DE>3.0, consumers can see with the naked eye that the printed colors of the packaged products are significantly different. In order to improve the color printing quality of large-format offset printing packaging products and change the color within the scope of licensing, it is necessary to systematically understand the production status and process of color printing packaging, and identify various reasons that affect color change. Do a good job of preventive measures and prevent them from all aspects, so that the color difference of packaged products can be effectively controlled. Color printing and packaging products production methods and characteristics At present, the production of color printing and packaging products mainly includes the following three production and production processes: Production of flexo printing The flexographic printing process uses a highly elastic resin relief plate, an anilox roller with holes, and an aqueous ink for color synthesis. The production process is relatively simple, suitable for field, line, text printing, product accuracy is higher, in the print color level of the embodiment and overlay accuracy is not as good as offset printing products. Preprinted color box production The preprinting is divided into a flexographic preprinting and a gravure preprinting method. The flexographic printing apparatus is used for the flexographic printing preprinting apparatus, and the gravure printing apparatus used for the gravure preprinting is the printing apparatus. Both of these processes are based on web-based printing. The investment is relatively large, the cost of plate making is high, and it is not easy to change the layout. The change operation is also relatively troublesome, and it is suitable for production of particularly large-volume products. The gravure preprinting adopts volatile solvent ink, uses a rotary machine with a higher degree of automation, has a short ink transfer path, and has an ink scraping device. The ink layer of the ink is uniform and thick, with rich color gradation and a good texture. Offset color box production The so-called offset printing refers to lithography, which is based on the principle of immiscible oil and water. On the same plane of the printing plate, the blank part of the printing plate is hydrophilic and oil-repellent, and the graphic part is lipophilic and hydrophobic, under appropriate pressure conditions. In the following, a printing method in which indirect printing is performed using a blanket as an intermediate is a printing method with the best color reproduction effect, the richest color gradation, the highest overlay accuracy, and the widest range of use. The three manufacturing processes have their own characteristics and some common points. According to the product structure of the current market, packaging products requiring high quality color printing mostly use offset ink box production processes. Therefore, in chromatic aberration analysis, the analysis of offset printing process is mainly used. In the process of promoting, improving, and improving the production level of offset color box (reducing color difference), it will certainly promote and promote the improvement of other production processes. Analysis of Color Differences in Offset Packaging Product Formation The printing process is a process of product reproduction. There are three phases in this process: the color decomposition phase (prepress), the color synthesis phase (printing phase), and the postpress processing phase. As the formation of color differences mainly in the prepress and printing two stages. Prepress Analysis In prepress design, the choice of color space, dot angles, number of screen lines, tone levels, etc. is a key prerequisite. It plays an important pre-reference role in color and can only be officially printed after proofing. The irregularity in the coordination between the prepress and printing stages is also the main cause of chromatic aberration. Due to the inconsistency of equipment, materials, and operating personnel used by different companies, the same product is outputting film on different devices, and the production effect of the film is biased. In this way, the synthesis of late colors causes hidden differences at the source, so in the prepress stage you should pay attention to the following: Manuscript design: Due to the different methods used by designers to create manuscripts, manuscripts designed by different design companies may have large differences, leading to distortion of subsequent processes and affecting the color of prints. Film product quality: Because each platemaking company uses its own situation and experience, it often uses different manufacturers and different types of film for production, due to the film base fog density, field density (excluding film base density), transparent Differences in the indicators such as the density of the transparent part of the screen, the density of the transparent part of the screen (excluding the film base), and the registration error (diagonal line) lead to great differences before printing, and there are differences in the printed matter colors. Linear control during hair piece: Film linearity mainly refers to the difference between the dot size on the film and the actual theoretical value. The quality of linearity directly determines the quality of the printed matter. For example: 50% of the outlets are theoretical, and the actual outlet is 40%. In this way, no matter how they are adjusted in the printing process, they will not be able to completely compensate for the dot losses caused during the filming process. The linear instability also causes the printing process to be unable to control reasonably. That is to say, with the same theoretical value of the dot network, different dot values ​​appear in the case of different films, and it is impossible to reasonably control the printing process. Therefore, stable, reliable, and accurate linearity are the most critical parameters in the filming process, and all of this depends on the design accuracy of the imagesetter itself and correct daily maintenance and calibration. The production of the film is not based on the actual working state of the offset printing press. The same set of film is arranged on different printing presses. Even if the used film is uniform, the color difference will occur due to the different performance of the printing press. The lack of standardized, data-based work processes, the same film produced in different time periods, due to the unstable state of the operator and equipment (exposure time, lamp usage time, the ratio of the developer configuration, the development temperature, the development speed and other factors ), the stability of the drying results is difficult to guarantee. Especially for products with low network cable, the loss of outlets will cause large deviations in hue and cause color differences accordingly. Print stage analysis Color sequence arrangement: the process of overlapping printing of different colors of ink in a certain order is called printing sequence. Scientifically and reasonably arranging the color sequence is conducive to achieving a gray balance and fully expressing the original color effect. Get accurate, colorful, and richly colored reproductions. A reasonable color sequence arrangement plays an important role in reducing the difficulty of operation and avoiding the occurrence of color aberration problems. The influence of color sequence on color cast: Generally, three colors are used to express the color tone, and the ink plate is used as the skeleton in the image to realize the rationality of the layout structure of the entire layout and achieve neutral gray balance. But in fact, achieving this goal is not easy. Because there are defects in the three primary color inks used in production, and there are differences in the paper processing conditions, it is bound to leave a distance between the printed matter and the original. Because the gray balance can not be achieved on the printing, color shifts will inevitably occur. Considering the transfer coverage of the ink, etc., choosing a reasonable printing sequence can be compensated to a certain extent to correct the color shift and facilitate color reproduction. The loss of control of the ink-and-wash balance: The loss of control of ink-water balance during the production process is an important cause of ink instability. Instability of ink output: When producing large batches of products, if the ink is not stirred, or if the ink is not cleaned in time, the ink residue formed during a long time of operation will affect the stability of the ink output and make the amount of ink smaller. , forming a color difference. When the running speed changes, if the output of the ink volume is not adjusted in time, there will be a color difference problem. Unstable printing pressure: When the printing pressure is unstable, there will be a difference in color due to pressure changes. In actual production, if the tape is not cleaned frequently, the paper powder deposited on the tape will cause a change in pressure, which usually manifests itself in changes during start-up production and completion of production. Irrational use of ink accessories: In order to change the printability, excessive use of ink accessories, easy to cause ink emulsification, resulting in imbalance of ink and ink, printing color. Causes of color differences in printed materials: Papers and inks produced by different manufacturers are important causes of color variations. Paper: The appearance of a paper depends on its optical properties, including the opacity, gloss, color (including whiteness), and smoothness of the paper, which directly affects the quality of the print. Ink: Ink is a uniform, colored, adhesive liquid formed by the processing of binders, colorants (mainly pigments), fillers and auxiliary materials. The ink is a pigment that has been thoroughly stirred and ground to disperse fine particles in the binder to form a viscous suspension dispersion. In the dispersion system, the pigment is a dispersed phase and the binder is a dispersion medium. The pigments and binder molecules form a solid-liquid, adhesive suspension dispersion system in the structure. This system is not a simple fluid but a complex and stable colloidal structure. Due to different production processes of inks produced by different manufacturers, the dispersion state of pigments and binders is different, resulting in differences in the stability of ink colloids. Other reasons Equipment: Due to different equipment used by different companies, and most of the domestic large-format offset presses are mostly two mobile phones, the operation is more difficult to control. In terms of personnel quality, due to fewer opportunities for operators to receive professional training, lack of operational skills and experience, and the lack of adequate awareness of the quality requirements for packaging products by packaging manufacturers. Hyaluronic Acid Pen,Injected Hyaluronic Acid Gel,Hyaluron Gun Atomizer Hyaluron Pe,Facial Filler Injection Hyaluronic Acid Shijiazhuang Asa Technology Co., Ltd. , https://www.hskinlift.com