Packaging printing ink color mixing skills
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In the printing process, no matter how it is printed, whether it is multi-color or monochrome printing, the primary problem encountered before printing is the color matching of the ink, so it is often necessary to select and blend the ink color. The color matching of ink is the most important part of printing. The true reproduction of color directly affects product quality and market space occupancy. In some large-scale enterprises, not only have special distributors, but also should do the best. Satisfy customers. Here's how to improve the quality of the ink through the ink color mixing technique:
Color matching principle
Any color is represented by three characteristics of hue, lightness and saturation, so the above three factors must be considered in the color matching process. Although black is theoretically the complete absorption of light, black ink still has luster. The ink is obtained by grinding a pigment (toner) and a resin binder. The particles of the pigment are surrounded by a layer of nearly transparent resin oil. This layer of resin oil has a refractive and reflective effect on the light, so we can feel that the black ink printing still has a certain luster on the substrate. Pigments usually account for 8-35% of the ink composition. The amount of the pigment determines the concentration of the ink and has a great influence on the ink, such as the relative density of the ink, transparency, heat resistance, light resistance and resistance to chemicals. Wait. In the ink color matching process, the ink used should be determined according to the actual printing process, the thickness of the ink layer, the printing substrate, and the like. When selecting the ink, the gloss, hue, tinting strength, and hiding power of the ink itself should be considered.
1) Gloss: Gloss can be measured by the instrument or by the naked eye, usually in the color matching process, only by naked eye.
Gloss actually refers to the extent to which the ink print sample reflects light in the same direction after being irradiated with light, which directly affects the appearance of printing, and 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-light or matte ink. It should also be considered whether it is the same ink, such as printing ink or surface printing ink. The same ink must be blended to avoid mixing errors and unnecessary losses.
2) Hue is the basic feature of color and is used for qualitative differences. When color matching, first consider whether the hue is consistent. The detection method is usually to scratch the color by scraping paper or to simulate printing, and compare the standard and the sample with human eyes.
3) The hiding power is the extent to which the ink covers its background color. The better the hiding power, the worse the transparency, and the transparency affects the efficiency of ink coloring and the degree of influence on the printed substrate.
4) The tinting strength is a method for indicating the concentration of the ink. The measurement is based on a certain amount of ink and then adding a certain amount of standard white ink to dilute and mix, and then comparing with the standard, the intensity of the tinting strength reflects the degree of color mixing of the ink. Affect the thickness of the printed film. Through the color identification (scratch paper scratch test), the difference between the ink sample and the standard sample in terms of gloss, hue and hiding power can be compared.
The specific method is as follows: the standard ink is placed in the upper left corner of the identification paper, the color ink is placed in the upper right corner, the thin coating portion is stretched at a nearly vertical angle with the squeegee paper, and the thick portion is quickly unfolded at an oblique angle. After the surface of the ink is dried, the hue of the ink can be observed in the thin portion, the hiding power and transparency of the ink are identified in the black strip portion, the difference in gloss between the two portions is judged in the thick portion, and the appearance of the entire color is observed, usually in black and color inks. White scratched paper, while white ink uses black scratched paper.
It is best to compare the color samples under the indirect indoor light source during the daytime, and should not be exposed to direct sunlight. At night, it is recommended to use a fluorescent tube for color evaluation and a color temperature of 5000±200~K. You can also use a self-made mixed light source: 3 6500K400W fluorescent tubes, 2 20W blue fluorescent tubes, and 6 100W tungsten lamps to fix them. It can be used inside a special cover, mainly for easy observation of color samples.
Color precautions
1) Carefully observe the color samples, pay special attention to the substrate to be printed, and select the ink from the roughness and smooth reflection of the substrate. For example, ink printing on a highly reflective aluminum sheet or can, and selecting a highly transparent ink will help to greatly enhance the metallic luster of the ink.
2) When selecting the ink required for color matching, avoid mixing too much ink as much as possible. Try to use an ink that is close to the standard color and made of a single pigment. The color matching uses too much color ink. The farther away from the standard color, the worse the brightness. The higher the matte level of the mixed color, the more it is impossible to modulate the primary color by color matching. Therefore, when the color matching can be used with two kinds of mixing, there is no need for three kinds, and the less the better.
3) Pay special attention to ink tinting strength. If the selected ink concentration is not high enough, the standard color density cannot be achieved no matter how it is blended.
4) When white and black inks need to be added, special attention should be paid to the added components and the accuracy of weighing. In all inks, the hiding power of white ink is extremely strong. Adding too much will not only dilute the color, but also prevent the bottom. The degree of reflective material. However, for printing uneven surfaces such as nylon cloth and paperboard, it is preferable to print a white color as a background color in order to ensure the appearance of the printed product. Since the black ink has a strong coloring power and is slightly inadvertent, if it is added too much, it is necessary to add a considerable amount of other color inks to adjust the color, thereby causing waste, so special attention is required.
5) When making a light-colored ink, judge how much white ink or varnish (dilution agent) should be added to the color of the ink film. Solvents (dilution water) are never allowed to be used to dilute the color. Too much solvent will not only affect the printing performance, but also damage the ink structure, causing the pigment to separate from the resin oil, causing precipitation or greatly reducing the gloss and brightness of the ink. .
Dark and light ink blending
The formulation of the ink can be divided into the formulation of dark ink and light ink. The so-called dark ink blending refers to the formulation of only the primary ink without adding any thinner, the amount of ink required for printing according to the printing, and the primary and secondary inks determined by color analysis and their proportions, will be the main The color ink and the secondary ink are blended together uniformly. The dark ink is divided into three types: monochrome, inter-color and multi-color. Monochrome refers to the blending of a primary color ink. Inter-color refers to the blending of two primary colors of ink. The complex color refers to a mixture of three primary color inks.
Any ink that is blended with a thinner is called a light ink. Pay attention to three points when deploying:
1) use white ink without thinner;
2) When whitening, mainly white ink, add a little color ink to white ink; 3) Color selection should be accurate, as follows:
Pink: mainly white, slightly pink, fluorescent orange
Jade color: mainly white, slightly added medium yellow, fluorescent orange
Beige: mainly white, slightly eclipsed, medium yellow, black
Light blue: mainly white, slightly added blue
Lake Blue: mainly white, slightly added hole blue
Gray: mainly white, slightly added hole blue, light yellow
Silver ash: mainly white, slightly silver paste, black ink
Xueqing: mainly white, slightly reddish, royal blue
Meat color: mainly based on thinner, slightly transparent orange red, medium yellow
Ivory color: mainly based on thinner, slightly added medium yellow, peacock blue, orange red.
How to improve the gloss of the ink film
1) Add an appropriate amount of varnish to the allowable range of color density;
2) coating the surface of the printed film with varnish or varnish;
3) Increase the transparency of the ink, choose high transparency ink or add appropriate amount of varnish, use smooth, strong reflection, and the reflection of the substrate increases the gloss:
4) Prevent the adsorption of the surface of the substrate and reasonably improve the smoothness of the printed surface of the substrate;
5) Pay attention to the temperature and humidity of the printing environment. When the plastic gravure printing is performed under high humidity and low temperature, the solvent volatilizes quickly, absorbs the heat around the ink film and causes the water vapor in the air to condense rapidly, making printing A mist is formed on the surface of the ink film, causing the ink layer to lose its luster. In the rainy season, special attention should be paid to controlling the temperature and humidity of the printing environment to ensure good printing results. Usually, the room temperature is 21-23%, and the humidity is controlled at 40%, which contributes to the true reproduction of the color.
Special color production
1) Gold and silver ink production: use tempered oil to add appropriate amount of gold powder and silver powder to mix and serve. Care should be taken to select the appropriate fineness of gold powder and silver powder, and also to select the varnish that is suitable for the printed substrate, and also to be prepared at the time of printing to prevent precipitation and delamination of the ink due to excessive rotation time. Ink can also be made by mixing silver powder with clear yellow and varnish.
2) Pearlescent ink: The pearlescent pigment is uniformly mixed with a suitable ratio of highly transparent ink or varnish. The ink has a strong hiding power and can lose the pearlescent effect.
3) Luminous ink: The ink has the effect of absorbing light energy for a certain period of time, so it can often emit light at night. It is called luminous ink or phosphorescent ink. The luminescent pigment is usually dispersed in a highly viscous varnish and stirred well.
All the above inks can not grind gold ink, silver ink grinding will damage the grinding equipment, pearl light, luminous, ink grinding will destroy the surface or crystal structure, and lose the desired effect.
Plastic printing
1) Ink color should be as much as possible using the same color of the ink produced by the ink factory, the color of the shaping ink is higher than the color of the two colors of ink;
2) If you want to use 12 kinds of inks to match colors, you should try to use the styling inks with similar colors to make the main blending;
3) When color matching, the ink type should be reduced as much as possible, because the more the color of the color matching ink, the higher the achromatic ratio, the lower the brightness and chroma of the ink color, so it is possible to use two colors to match the three colors. ;
4) The plastic film is a non-absorbent material. It is not possible to dilute the color ink with a thinner. White ink should be added to dilute it;
5) Different manufacturers, different types of ink are not mixed. This will affect the gloss, purity and drying speed of the white ink.
In summary, when blending ink colors, you must carefully grasp each level to match the good color.