Matters needing attention during the processing an

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Precautions for packaging color printing processing

1 The whiteness of the paper is the basis for bright printing colors. It is ideal that the paper can reflect nearly all the color light from the commissioning experiment, while the paper containing gray, black, cyan, red and other colors will absorb part of the incident color light, which will affect the hue, lightness and saturation of the imprint, and finally show the difference in color. This is equivalent to adding some other inks to the ink, which shows the impurity of the excellent ink, thus giving people a feeling of darkness, turbidity and color deviation

2. The main components of the paper are cellulose, rubber, fillers, etc., while the flowing part of the ink is the binder, and the pigment of the ink is attached by the binder drying on the surface of the paper

3. The main components of paper and ink are asymmetric molecules. When they are close to each other, they rely on the secondary binding force to make the molecules adhere to the paper

4. Nowadays, most of the packaging and decoration printing materials use coated white board, wood pulp coated white board, ordinary box board, wood pulp coated box board, kraft paper and white cardboard 17 Application voltage: AC 220v/50hz single-phase two wire + protective ground wire 518 Total power: 0.5KW. Due to the difference of production process in different paper mills, the surface whiteness and smoothness of paper are significantly different

5. At the moment of printing, the low molecular part with high fluidity in the ink binder is pressed into the larger pores of the paper, and the binder begins to separate from the ink

6. The pigment content of the ink is high, and a large number of small capillaries can be formed in the ink film. These large numbers of small capillaries have the ability to retain the binder, which is much greater than the fiber gap on the paper surface to absorb the binder

7. If the pigment content is low, the ink will adhere to the surface of the paper, causing most of the connecting materials to enter the gap of the paper, resulting in thin ink film on the substrate, exposed pigment particles, and the final color is not bright

II. Influence of ink transfer and rolling on the color brightness of printed products

1 When the color ink is coated, the ink bucket and ink roller are not clean and mixed with other color ink, which is bound to cause color deviation and also cause the color not bright. Therefore, when changing colors, be sure to clean the ink bucket, ink roller and water roller, especially when changing dark colors to light colors. Usually, after the dark ink is cleaned, shovel some of the light ink to be used, beat it evenly for a period of time, and then clean it

2. For two-color and multi-color offset printing machines, especially the equipment where the upper and lower units share an imprinting cylinder, we should pay more attention to the occurrence of color mixing. 1. The average plastic consumption of the vehicle may reach more than 500kg/vehicle. Once the color is mixed, it will certainly cause color deviation, resulting in the lack of bright color ink

3. The influence of ink over emulsification and additives on the color brightness of printed matter the traditional offset printing mainly relies on the balance of water and ink to complete the printing process. According to the analysis of ink transfer process, ink emulsification is inevitable. However, the over emulsified ink will cause the color of printed products to fade and become old, resulting in the reduction of color brightness

4. In offset printing, various additives, such as diluent and drier, should be added as required. These additives add too much, sometimes will also affect the printing color brightness. Diluents include white ink, white oil, etc. White oil is mainly an emulsion composed of magnesium carbonate, stearic acid, inking oil and water. This emulsion will make the ink emulsion, resulting in dull color

5. The driers are mainly metal soaps, which are also strong emulsifiers. A small amount of driers can stabilize the emulsification of ink, but excessive addition will cause serious emulsification of ink

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