Printing Colors and Management (I)

The ink management mainly realizes the control of the color quality parameters of the ink through the detection of the hue of the ink, the coloring power and the light fastness, and eliminates the color shift from the source.
Since the flexographic printing was introduced in the early 1990s, printing quality has been far lower than offset and gravure printing for a long period of time. In recent years, with the adoption of new materials and new technologies, the manufacturing precision of flexo presses has been continuously improved, especially the emergence of photosensitive flexible resin plates, which has greatly improved the quality of flexo printing, and it has its own positioning in the market. The market share has gradually increased.
At present, flexo printing is better applied in the fields of cigarette packs, medicine boxes, and trademarks, and it accounts for the largest proportion in corrugated box printing. The traditional printing of corrugated boxes makes people feel rough and dirty, and can only print simple texts and designs, and there is no technical content. With the rapid development of flexographic printing, the appearance of fine anilox rollers, photosensitive resin plates, and high-precision printers enables corrugated cartons to use multi-color and half-tone printing to achieve perfect reproduction of fine color patterns. There are many large-scale well-known companies, such as: Johnson & Johnson, LG, Haier, Lihua, and many other products have used the flexo color printing packaging. These companies are very strict with regard to quality, and they are very demanding on the effect of copying the special color of corporate image. Many printers lacked systematic color control methods, which made it difficult to effectively control color deviations. As a result, incidents involving complaints from customers, complaints, and even compensation for returning goods also occurred. These enterprises were in a great headache. Here, I would like to talk about the color management of flexographic printing, control, and combined with my own experience, and talk about some ideas and some specific methods of operation for readers' reference.
Flexo printing is the application of low-viscosity water-based ink to the flexographic printing plate by an anilox roller, and then directly imprinted on the substrate to complete the printing. It is different from the offset printing, gravure printing, etc. It has its unique process characteristics, so in color Management also has its own characteristics and methods.
The color management of flexo printing involves various aspects such as paper, ink, printing machinery, color printing, operators, and daily management. It can be described by a system. Only the parts of the system are well connected and operating normally. The printing color is Only by effective control can we have stability and correctness.
First, the ink management The quality of the ink directly affects the correctness and stability of the color of the printed product. The water-based ink used in flexographic printing has the characteristics of low viscosity and small pollution. The ink management mainly realizes the control of the color quality parameters of the ink through the detection of the hue of the ink, the coloring power and the light fastness, and eliminates the color shift from the source. Ink detection and related data can be provided by the supplier, but can also be detected by the printing company itself. I suggest that printing companies conduct testing of some important items on their own. Therefore, the detection methods for these items are not complicated, as long as less funds and equipment are used.
1, ink hue, tinting power to detect hue, tinting strength is the basic item of ink detection, they have a great influence on the color of the ink. Hue is a specific feature of the ink color, optically corresponding to a certain wavelength, frequency of light, such as: red, yellow, blue refers to the hue of the ink. Coloring power refers to the size of an ink that affects the color change of another ink. When spot color inks are blended, when the hue of one of the original inks changes, the color of the spot color inks that are picked up will change. For example, when the hue of the original ink is yellowish than before, the spot ink that is prepared will have the effect of increasing the yellow color; if the coloring power of the red original ink is strong, it will have the effect of increasing the red color. When this color deviation exceeds a certain range, visual inspection can be found, leading to customer complaints. Therefore, to ensure the correctness of the hue of the printing ink and the stability of the coloring power, it is very important to control the color of the printed matter.
1) Detection of hue For the newly provided ink, it is generally necessary to adjust its viscosity to the upper machine viscosity, use a printing press to proof, print the color sample of this ink in the field version, or adjust the pressure of the ink in the color development wheel. Drop a few drops, drag with a certain pressure and speed on the surface of the substrate, and display a ribbon as a color sample. Observe the effect of these proofs. If the ink layer is even and smooth, the coloring is good, there is a certain luster, the ink is thick, and the color is the same as the standard color card provided by the supplier (which can be provided by the ink factory), then the hue of the ink is shown. Meet the requirements. Finally, a certain amount of ink for the detection may be sealed and stored as a reference wet color sample for the next hue detection.
For inks that have been used, the viscosity of the ink can be adjusted to an appropriate value, and a good sample can be made with the color wheel, which is compared with the qualified color sample or standard color sample retained by the previous printing, and the color hue can be initially detected. Another method is to place the detected ink with the wet color sample of the ink that has passed the last test. Several drops of each color are separated by about 1 cm on the color wheel, and side by side. At this point, two adjacent ribbons will be left on the printing paper. Comparison of these two ribbons can more accurately determine whether the hue is the same.
2) Coloring power detection The coloring power of ink is determined by using white ink as the reference color sample to determine the strength of the coloring force by the degree of influence of an ink on the white ink. The test of coloring power is to add the test ink and the standard color ink in a small beaker, stir and then make a version, and then compare and judge the color strength of the ink against the standard tinting strength color sample. The specific approach is as follows:
10g of the test ink and 100g of standard white ink are added into a small beaker, and the mixture is stirred and evenly patterned with a color wheel. The color sample produced is compared with the standard ink color strength card provided by the supplier. If the ink is light, the ink color Weak, if the ink is dark, it indicates that the coloring power of this ink is strong. If it is basically the same, it means that the coloring power is qualified.
In addition, the strength of the change in coloring power can be detected by increasing the weight of the test ink or the standard white ink. (To be continued)