Plastic intaglio printing is a common printing method. Due to good color reproducibility, realism, strong three-dimensional effect, easy to carry the finished product bag, aesthetics and other factors, it is widely used in various types of flexible packaging, such as food packaging, pharmaceutical packaging and other fields. In the printing process, no matter what kind of printing method is used for printing, whether it is multicolor or monochrome printing, the first problem encountered before printing is the deployment of ink color. No matter how bright the ink, if the operator does not understand some of the ink performance and color knowledge, mixed ink can not achieve a satisfactory appearance and quality level. The deployment of ink colors is a crucial part. Some large-scale companies also have specialized dispensers. I have been engaged in the flexible packaging industry for many years, and now I will sort out the written opinions on the problem of the color grading process and hope to help my colleagues.
1 color matching principle
Any color is represented by the three characteristics of hue, lightness, and saturation. The above three characteristics must be considered in the color matching process. In the ink color matching process, the ink type should be selected according to the actual printing process, the ink layer thickness, the printing substrate and other conditions, and the ink itself should be considered for its luster, hue, coloring power, hiding power, and the like.
1 gloss. Gloss can be measured either with the instrument or with the naked eye. It is usually observed with the naked eye during the color matching process. For special situations, it must be measured with instruments such as chromatographs. Luster is actually the size of the ability of ink printing to reflect light in the same direction after being irradiated with light, which directly affects the appearance of printing, which is a very important indicator. At the same time, when selecting the ink, it is necessary to distinguish whether the ink itself is a bright, semi-glossy or matte type ink, and it should also be considered whether the ink of the same type is used. If the printing ink is printed in India (chlorinated polypropylene resin type) or table printing (polyamide resin) ink, it must be prepared for the same ink to avoid mixing errors and cause unnecessary losses.
2 hue. Is the basic characteristics of color, used for qualitative differences. When matching colors, the first thing to consider is whether or not the hue is the same. The detection method is usually to observe and compare by scraping.
The specific way to observe hue is:
1 On a flat glass viewing platform, take the standard sample and the color pattern 1 to 2 cm apart.
2 Take a scratch paper to flatten the glass stand, take the color ink, and use a glass crowbar to make a sample and compare the results.
There are two important factors involved in the comparison of palette results:
1 hiding power. The degree to which the ink covers its background color, the better the hiding power, the worse the transparency. The level of transparency affects the efficiency of ink trapping and the extent to which it is affected by the printed substrate. Generally, dark ink has stronger hiding power than light color, such as blue is lighter yellow, and ink hiding power is good and bad, but also has a close relationship with the ink itself, such as the thickness factor, usually the hiding power of white ink is good. The bad is related to the thickness of titanium dioxide particles, coarse particles, poor hiding power, easy to print agglomerates, fine particles, good hiding power, uniform surface, smooth and delicate. The white ink generally requires a diameter of no more than 15 μm, and other colors of ink cannot exceed 12 μm.
2 coloring power. A method of expressing ink density. The measurement is to take a certain amount of color ink, mixed with a certain amount of standard white ink, and then compared with the standard sample, the color strength reflects the ink mixed color intensity. The difference in gloss, hue, and hiding power between the ink sample and the standard sample can be compared by the color identification (scrape-stained-paper scraping test). The specific method is as follows: Put the standard ink in the upper left corner of the scraping paper and the color ink in the upper right corner. Make the scraper at a nearly vertical angle to the scraping paper, gently flatten the standard and color inks to be compared, and after the ink surface is dry, determine the difference in gloss between the two under a certain light source, and observe the appearance of the entire color. Normally black and color inks use white scratch paper, while white ink uses black scratch paper.
When observing color samples, it is best to compare them under indirect light sources during the daytime, and it should not be exposed to direct sunlight. It is recommended to use at night observation: “Color price fluorescent tube and color temperature 5000±200°K. You can also use self-made hybrid light source: 2 blue fluorescent tubes, 3 6500K400W fluorescent tubes, 6 100W tungsten filament lamps, fixed in In a special hood, it is easy to observe color samples."
2 color matching notes
1 Carefully observe the color samples, paying particular attention to the printed substrate, and select the ink from the rough and smooth reflectance of the substrate. For example: For a smooth, highly reflective aluminum plate or can, choosing a high transparency ink will help greatly enhance the metallic luster of the ink.
2 When selecting inks for color matching, avoid mixing too much ink as much as possible. When using two kinds of inks for color matching, there is no need to use three types. Try to do as little as possible. Use inks that are close to standard colors and made from a single pigment. Too much color ink is used for color matching, and the farther away from the standard color, the worse the brightness.
3 Pay special attention to the tinting strength of the ink. If the selected ink concentration is not high enough, the standard color concentration cannot be achieved regardless of how it is formulated.
4 When it is necessary to add black and white ink, special attention should be paid to the amount of weight added and the accuracy of weighing. In all inks, the hiding power of white ink is extremely strong, and adding too much will not only dilute the color, but also will prevent the reflection of the substrate. However, for the printed uneven substrate, such as: nylon cloth, cardboard, in order to ensure the appearance of the print, it is best to print a white layer as the background color. Due to the strong coloring power of the black ink, adding too much ink to the ink requires adding a considerable amount of other color inks to adjust the color, resulting in waste. Therefore, special attention is required.
5 When producing light color inks, the degree of light transmission of the ink film should be judged, and how much white ink or varnish (dilution agent) should be added for coloring. Never use solvents (diluents) for light colors. Excessive solvent addition will not only affect the printing performance, but will also destroy the ink structure and cause separation of the pigment from the resin oil. Precipitation or greatly reduces the gloss and brightness of the ink.
(to be continued)
1 color matching principle
Any color is represented by the three characteristics of hue, lightness, and saturation. The above three characteristics must be considered in the color matching process. In the ink color matching process, the ink type should be selected according to the actual printing process, the ink layer thickness, the printing substrate and other conditions, and the ink itself should be considered for its luster, hue, coloring power, hiding power, and the like.
1 gloss. Gloss can be measured either with the instrument or with the naked eye. It is usually observed with the naked eye during the color matching process. For special situations, it must be measured with instruments such as chromatographs. Luster is actually the size of the ability of ink printing to reflect light in the same direction after being irradiated with light, which directly affects the appearance of printing, which is a very important indicator. At the same time, when selecting the ink, it is necessary to distinguish whether the ink itself is a bright, semi-glossy or matte type ink, and it should also be considered whether the ink of the same type is used. If the printing ink is printed in India (chlorinated polypropylene resin type) or table printing (polyamide resin) ink, it must be prepared for the same ink to avoid mixing errors and cause unnecessary losses.
2 hue. Is the basic characteristics of color, used for qualitative differences. When matching colors, the first thing to consider is whether or not the hue is the same. The detection method is usually to observe and compare by scraping.
The specific way to observe hue is:
1 On a flat glass viewing platform, take the standard sample and the color pattern 1 to 2 cm apart.
2 Take a scratch paper to flatten the glass stand, take the color ink, and use a glass crowbar to make a sample and compare the results.
There are two important factors involved in the comparison of palette results:
1 hiding power. The degree to which the ink covers its background color, the better the hiding power, the worse the transparency. The level of transparency affects the efficiency of ink trapping and the extent to which it is affected by the printed substrate. Generally, dark ink has stronger hiding power than light color, such as blue is lighter yellow, and ink hiding power is good and bad, but also has a close relationship with the ink itself, such as the thickness factor, usually the hiding power of white ink is good. The bad is related to the thickness of titanium dioxide particles, coarse particles, poor hiding power, easy to print agglomerates, fine particles, good hiding power, uniform surface, smooth and delicate. The white ink generally requires a diameter of no more than 15 μm, and other colors of ink cannot exceed 12 μm.
2 coloring power. A method of expressing ink density. The measurement is to take a certain amount of color ink, mixed with a certain amount of standard white ink, and then compared with the standard sample, the color strength reflects the ink mixed color intensity. The difference in gloss, hue, and hiding power between the ink sample and the standard sample can be compared by the color identification (scrape-stained-paper scraping test). The specific method is as follows: Put the standard ink in the upper left corner of the scraping paper and the color ink in the upper right corner. Make the scraper at a nearly vertical angle to the scraping paper, gently flatten the standard and color inks to be compared, and after the ink surface is dry, determine the difference in gloss between the two under a certain light source, and observe the appearance of the entire color. Normally black and color inks use white scratch paper, while white ink uses black scratch paper.
When observing color samples, it is best to compare them under indirect light sources during the daytime, and it should not be exposed to direct sunlight. It is recommended to use at night observation: “Color price fluorescent tube and color temperature 5000±200°K. You can also use self-made hybrid light source: 2 blue fluorescent tubes, 3 6500K400W fluorescent tubes, 6 100W tungsten filament lamps, fixed in In a special hood, it is easy to observe color samples."
2 color matching notes
1 Carefully observe the color samples, paying particular attention to the printed substrate, and select the ink from the rough and smooth reflectance of the substrate. For example: For a smooth, highly reflective aluminum plate or can, choosing a high transparency ink will help greatly enhance the metallic luster of the ink.
2 When selecting inks for color matching, avoid mixing too much ink as much as possible. When using two kinds of inks for color matching, there is no need to use three types. Try to do as little as possible. Use inks that are close to standard colors and made from a single pigment. Too much color ink is used for color matching, and the farther away from the standard color, the worse the brightness.
3 Pay special attention to the tinting strength of the ink. If the selected ink concentration is not high enough, the standard color concentration cannot be achieved regardless of how it is formulated.
4 When it is necessary to add black and white ink, special attention should be paid to the amount of weight added and the accuracy of weighing. In all inks, the hiding power of white ink is extremely strong, and adding too much will not only dilute the color, but also will prevent the reflection of the substrate. However, for the printed uneven substrate, such as: nylon cloth, cardboard, in order to ensure the appearance of the print, it is best to print a white layer as the background color. Due to the strong coloring power of the black ink, adding too much ink to the ink requires adding a considerable amount of other color inks to adjust the color, resulting in waste. Therefore, special attention is required.
5 When producing light color inks, the degree of light transmission of the ink film should be judged, and how much white ink or varnish (dilution agent) should be added for coloring. Never use solvents (diluents) for light colors. Excessive solvent addition will not only affect the printing performance, but will also destroy the ink structure and cause separation of the pigment from the resin oil. Precipitation or greatly reduces the gloss and brightness of the ink.
(to be continued)
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