Printing iron ink special process

Imprinted ink has the characteristics of resistance to mechanical processing, and its performance is characterized by higher viscosity and less fluidity, which is very unfavorable for the transfer of ink during printing. In order to improve its printability, an appropriate amount (less than 5%) of diluent is often added to reduce the ink stickiness while increasing the fluidity. However, the amount of diluent added can not be too much, because after tinplate printing is completed, it should be baked in an oven at 150°C-180°C for 10-15 minutes. During the baking process, the thinner and the ink are dried together. If the diluent is added in excessive quantity, the ink is too thin, and the dots will be made ridiculous after baking, and the actual color will be changed accordingly, resulting in a difference between the actual printing color and the standard color draft.

In tinplate printing, the product coated with white cocoa as a primer accounts for most of the printed iron, and white cocoa as a primer actually simulates the effect of white paper. As far as the current use of white cocoa is concerned, basically none of them is white, and there are color casts. For example, yellow phase can be red, but red phase can be, blue phase can be red, blue and red phase (purple phase) can be small, and each white can have different whiteness. These factors determine the different color and whiteness of white cocoa in the spot color ink mix has different effects on the spot color ink hue. For example: 1 print a warm color on a blue or blue-red chrome, the printed color will be darker than the ink itself; 2 print a green color on a yellowish cocoa, the printed color will be better than the ink It is yellowish and yellowish green in itself.

In short, when the red-phase spot color ink is printed on its complementary color-blue phase and blue-red phase (purple phase), the printed color will be darker than the ink itself; the green-phase spot color ink can be used in its complementary color. D - red, blue and red phase (purple phase) printed on the dichotomy, the printed color will be darker than the ink itself; the blue phase spot color ink in its complementary color can be printed on the yellow phase can be The printed color will be darker than the ink itself.

Discoloration of ink after baking at high temperature

Iron printing inks are heat-curing inks. One of their technical requirements is that the color does not change after high-temperature baking. However, in actual production, some hue inks are more or less discolored after baking, for example, white ink, diluting ink, and ink formed by using a large amount of white ink and diluting ink. These inks are baked many times. Yellowing occurs, especially for spot-color inks formulated with a large amount of diluting agent, and the color change will be great after many baking. For example, with a large amount of dilute agent added to the blue light formulated by the blue ink, after many baking light blue may become dark blue special. Process planners should fully consider when formulating the printing process, and try to put these Beijing-based inks that have been baked and changed color on the final printing.

Color change before and after polishing

The last process of printing is varnishing. The purpose of the varnish is to protect the pattern and prevent damage. The second is to increase the gloss and increase the appearance. In general, the Indian iron varnish will be yellowed after baking at high temperature, and the reflectivity of the light oil layer will increase, so the color of the varnish will generally be brighter than that of the varnish. However, some optical oils contain brighteners and are blue in the light. Therefore, after using the varnish, the color of the varnish will be bluer than the original. The overall hue is the superposition of the color of the ink itself and the bluish color of the varnish.

Gold, silver ink or metal color spot ink formulated with gold or silver ink

The printed iron and silver inks are colored by metal powders such as gold and aluminum. Among them, printed iron ink is a printing ink prepared by grinding copper powder, and iron printing ink is an ink prepared by grinding aluminum powder.

The chemical properties of gold and silver powders in printed iron and silver inks are generally not stable enough. When acid, alkali, water vapor, sulfide gas, and carbonic acid gas are encountered, a chemical reaction will occur and the ink will lack the metallic color. The color change of the metal is changed from golden yellow to reddish brown and then turned blackish. Because copper can produce red cuprous oxide during initial oxidation, it becomes black copper oxide after further oxidation; in addition, the gold powder easily becomes basic copper carbonate under the conditions of relatively concentrated carbon dioxide and large humidity, So the gold ink on the prints gradually darkened. After the silver ink is discolored, it becomes grayish and lacks a silver metallic texture.

Printing ink thickness is different

We know that the same ink print thickness is different, and the color it displays is also different. In actual printing, the thickness of the ink layer is controlled by the printing pressure and the amount of ink. In general, printing pressure adjustment will not change, so the thickness and uniformity of the ink layer in printing is controlled by How much ink to achieve. Most domestic iron printing machines still rely on the manual adjustment of the amount of ink screws to control the amount of ink. Since the human adjustment is affected by many factors, the thickness of the printed ink layer may be uneven, and the color of the ink may also be different. There is a difference with the standard color draft.

In the actual production, these factors affecting the color change of the printing ink will be met. This requires the operator to understand and grasp the changing rules of these factors, and then according to the actual situation, allocate the appropriate ink ratio, and develop a reasonable printing process, reduce Repeatedly printing ink color changes, which is conducive to saving downtime and increase production efficiency. This work is also the basic work that any Indian Railway company should attach importance to and make unremitting efforts.