Standardized management performance test of the ho

2022-07-25
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Standardized management of ink: performance test

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

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 little pollution. 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. Ink testing and related data can be provided by the supplier or tested by the printing enterprise itself

1. Ink hue and tinting power detection

hue and tinting power are the basic items of ink detection, which have a great impact on the color of ink. Hue is the specific feature of ink color. Optically, it corresponds to light of a certain wavelength and frequency. For example, red, yellow and blue refer to the hue of ink. Tinting power refers to the extent to which one ink affects the color change of another ink. When dispensing spot color ink, when the hue or appearance 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 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 the 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

2. Hue detection

for newly provided inks, the viscosity should generally be adjusted to the machine viscosity, proofed with a printing machine, and the color sample of the ink should be printed in the field version, or the ink should be dropped 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 basically the same as the standard color card provided by the supplier (which can be made and provided by the ink factory), it indicates that the color phase of the ink meets the requirements. Finally, a certain amount of ink for this test can be sealed and stored for reference. 1. First, check whether the installation level of the hydraulic universal testing machine is the reference wet color sample for the next hue test

for the ink that has been used, the viscosity of the ink can be adjusted to an appropriate value, and the color sample can be made with the color developing wheel, which can be compared with the qualified color sample or standard color sample retained by the light bar of the last printing tensile testing machine, so as to preliminarily detect whether the color phase is consistent. The other method is to make several drops of the tested ink and the wet color sample of the last qualified ink at a distance of about 1cm on the color developing wheel, and arrange them in parallel

at this time, two adjacent color bands will be left on the master paper. By comparing these two color bands, we can accurately judge whether the hue is the same

3. Tinting power detection

ink tinting power detection uses white ink as a reference color sample to judge the strength of its tinting power through the impact of an ink on white ink. The test of colouring power is to add the ink to be tested and the standard color ink into a small beaker, mix them evenly, and then make a version, and then compare and judge the colouring power of the ink against 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. Compare the color samples with the standard ink color card provided by the supplier. If the ink color is light, it means that the ink is weak. If the ink color is dark, it means that the ink is strong. If it is basically the same, it means that the ink is qualified

in addition, the change of tinting power can be detected by increasing the weight of the ink to be tested or the standard white ink. If the ink color is too light, the weight of the ink to be tested can be appropriately increased. For example, add 2G of the ink to be tested in a small beaker, stir it evenly, and then use the color developing wheel to make the color sample. If it is consistent with the standard color sample, calculate according to (10 + 2):100 = 10:x, and then we can deduce that x = 100 1012 = 83.3 (g), indicating that the coloring power of this color ink is only 83.3% of the standard color ink, which can also be said to be 16.7g weaker

if the ink color is too dark, the weight of white ink can be appropriately added. If 10g standard white ink is added to the small beaker and the printing color sample is consistent with the standard color card, press 10 ∶ 10 = 10 ∶ x = 110 (g), indicating that the coloring power of the ink to be tested is 110% of that of the standard ink, which can also be said to be 10g stronger

the X above represents the weight of the white ink when a certain amount of white ink is added to 10g of the ink to be tested and meets the standard colorability color card, that is, the strength of the colorability is measured by the amount of white ink

in addition, there is also a wet color sample comparison method, that is, the wet color sample of the dye power test of the ink to be tested and the wet color sample of the dye power test of the previously qualified ink are arranged side by side on the color developing wheel, and the wet color sample is compared after the color sample is printed. This detection method eliminates the disadvantage that there is color deviation between wet color samples and dry color samples, which has an adverse effect on the evaluation of the real results. Because they are wet color samples and close to each other, the color comparison is convenient and the accuracy is higher

after the coloring power and hue test, remember to keep the wet and dry color samples during the test, especially the wet and dry color samples of standard ink, which must be sealed and marked for the next test. As the spot color requires a stable color, the hue of the ink is required to be correct, and the coloring power is required to be stable. The general standard is: it is acceptable to seize the day within 10%, and it is qualified within 5%. It cannot be too high or too low

4. Detection of ink viscosity

liquid ink has relatively low viscosity and good fluidity. The method of detecting viscosity is also very simple. It only needs a viscosity cup and a stopwatch to complete the detection of ink viscosity

the specific operation method is: first stir the ink evenly, then immerse the viscosity cup in the ink, and then lift the viscosity cup out at a uniform speed. When the viscosity cup is just pulled out of the ink surface, press the stopwatch to watch the ink flow; When the ink just has a cut-off point, press the stop watch immediately. At this time, the time value on the stopwatch represents the viscosity of the ink. The viscosity is high and the number of seconds is large; Low viscosity and few seconds. Due to different temperatures, the viscosity of the ink will change accordingly. Therefore, the general detection temperature is fixed at 25 ℃

it is worth mentioning that there is no obvious correlation between the temperature and the color of the ink, but it will have some impact on the performance of the ink when it is printed on the machine

5. Light fastness test of inks

light fastness of inks refers to the ability of inks to maintain a stable color after exposure to light. The ink with poor light resistance will fade after a period of illumination. The color of some printed materials meets the requirements when they are printed in the printing plant, but the color deviation will occur after they are used at the customer for a period of time. This is mostly the reason

here is a method to roughly test the light resistance of ink: divide the field color samples after printing or plate printing into two parts, one part is exposed to sunlight for about 4 hours, and the other part is placed in a dark place; Or fold the color sample in half and place it under the sun. Part of the printing face up to let the sun shine, and part of the printing face down to the backlight. After 4 hours, according to the color deviation of the color samples of the two parts in which lixinhai holds 30% of the equity of Yongxing new energy, if there is an obvious color deviation, it indicates that the light resistance of the ink is unqualified

when purchasing ink, the printing factory shall require the ink supplier to provide products with accurate hue and stable coloring power, and keep a certain safety stock, so as not to break the material

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