The hottest printing color and management

Printing color and management (Part 1)

ink management mainly realizes the control of ink color quality parameters through the detection of ink hue, coloring power and sun resistance, so as to eliminate color deviation from the source

since flexographic printing came into being in the early 1990s, the printing quality has been much lower than offset printing and gravure printing for a long time. In recent years, with the adoption of new materials and new technologies, the continuous improvement of the manufacturing accuracy of flexo printing machines, especially the emergence of photosensitive flexible resin plates, has greatly improved the quality of flexo printing, and has its own positioning in the food market, and its market share has gradually increased

at present, flexographic printing is well used in cigarette boxes, medicine boxes, trademarks and other fields, while it accounts for the largest proportion in corrugated box printing. Traditional corrugated box printing makes people feel rough, dirty and dark, and can only print simple words and patterns, not to mention any technical content. Today, with the vigorous development of flexographic printing, the emergence of fine grain roller, photosensitive resin plate and high-precision printing machine, corrugated boxes can also be printed with multi-color and eye tone, so as to realize the perfect reproduction of fine color patterns. At present, many large well-known enterprises, such as Johnson & Johnson, LG, Haier, Lihua, etc., have adopted flexible color printing for the outer packaging of many products. These enterprises have very strict requirements on quality, and are even more demanding on the reproduction effect of the special color related to the corporate image. Due to the lack of systematic color control methods, many printing plants are difficult to effectively control the color deviation. Therefore, customer complaints, complaints, and even return compensation events also occur from time to time, which makes these enterprises feel very headache. Here, I would like to talk about some views and specific operation methods on the color management and control of flexographic printing, combined with my own experience, for readers' reference

flexographic printing is to apply low viscosity water-based ink to the flexographic plate through the roller, and then directly imprint it on the substrate to complete printing. It is different from offset printing, gravure printing, etc., and has its unique process characteristics, so it also has its inherent characteristics and methods in color management

the color management of flexographic printing involves paper, ink, printing machinery, printing color samples, operators, daily management and other aspects, which can be described by a system. Only when all parts of this system are well connected and operate normally, the printing color can be effectively controlled, stable and correct

I. ink management

the quality of ink directly affects the correctness and stability of the color of printing products. The water-based ink used in flexographic printing has the characteristics of low viscosity and low pollution. Ink management mainly realizes the control of ink color quality parameters through the detection of ink hue, coloring power and sun fastness, so as to eliminate color deviation from the source. Ink testing and related data can be provided by the supplier or tested by the printing enterprise itself. I suggest that the printing enterprises should test some important items by themselves. Therefore, the detection methods of these items are not complex, and they can be achieved as long as they invest less money and equipment

1. Ink hue, tinting force detection

hue, tinting force is the basic item of ink detection, and they have a great impact on the color of ink. Hue is the specific feature of ink color. Optically, light corresponding to a certain wavelength and frequency, such as red, yellow and blue, refers to the hue of ink. Coloring power refers to the influence of one ink on another oil, which aims to deepen the understanding of graphene performance and control the degree of ink color change. When the spot color ink of villagers' houses is deployed in the southwest of the river, when the hue or color of one of the original ink changes, the color of the spot color ink will change. For example, when the hue of the original ink is more yellow than before, the spot color ink prepared will have the effect of increasing yellow; If the coloring power of red ink is strong, it will have the effect of increasing red. When this color deviation exceeds a certain range, it can be found by visual inspection, resulting in customer complaints. Therefore, it is very important to control the color of printed matter to ensure the correctness of printing ink hue and the stability of coloring power

1) hue detection

for newly provided inks, generally, the viscosity should be adjusted to the machine viscosity, proofed with a printing machine, and the color sample of the ink should be printed with a field version, or the ink should be dropped several drops on the color wheel with adjusted pressure, dragged on the surface of the substrate with a certain pressure and speed, and a color band should be displayed as the color sample. Observe the effect of these samples. If the ink layer is uniform and smooth, the coloring is good, there is a certain gloss, the ink color is thick and solid, and the color is the same. The standard color card provided by the supplier (which can be made and provided by the ink factory) is basically the same, it indicates that the color phase of this ink meets the requirements. Finally, a certain amount of ink for this test can be sealed and stored as a reference wet color sample for the next hue test

for the ink that has been used, you can adjust the viscosity of the ink to an appropriate value, use the color developing wheel to make a color sample, and compare it with the qualified color sample or standard color sample retained in the last printing, so as to preliminarily detect whether the hue is consistent. The other method is to put the wet color sample of the tested ink and the ink that passed the last test on the color wheel, with a distance of about 1cm, and arrange several drops of each drop in parallel. At this time, two adjacent color bands will be left on the master paper. By comparing these two color bands, we can judge whether the hue is the same more accurately

2) tinting force detection

ink tinting force detection uses white ink as a reference to improve the up and down sliding performance of the force measuring piston. According to the color sample, the intensity of the tinting force can be judged by the impact of an ink on the white ink. The test of colouring power is to add the ink to be tested and the standard color ink into a small beaker, stir it evenly, and then make a version, and then compare and judge the colouring power of the ink with the standard colouring power color sample. The specific methods are as follows:

Add 10g of ink to be tested and 100g of standard white ink into a small beaker, mix it evenly, and then print with a color developing wheel. The color samples are compared with the standard ink coloring power color card provided by the supplier. If the ink color is light, it indicates that the ink coloring power is weak; if the ink color is dark, it indicates that the ink coloring power is strong; if it is basically the same, it indicates that the coloring power is qualified

in addition, the intensity of the change in coloring power can be detected by increasing the weight of the ink to be tested or the standard white ink. (to be continued)