Screen printing ink deployment

In order to successfully perform screen printing, preparations for printing materials (inks), substrates, plates, etc. must be done. If the type of ink used is appropriate, the ink color, viscosity and thinner are appropriate; the size, type, quantity of the substrate, whether the surface needs to be processed; whether the printing machine parts are operating normally, the surface of the printing table is flat; the size of the printing plate is Accuracy, accuracy, and so on.

First, ink deployment

Before printing, the ink should have good application and printability, and if necessary, proper blending should be done.

1. Toning. Prior to ink distribution, the amount of ink consumed per color print should be calculated first, so that the amount of ink dispensed is appropriate. Especially for the two-fluid reaction type ink, the ink transfer amount should be calculated according to the curing speed and printing speed.

In order to obtain the correct color, the ink transfer should be performed under stable natural light, and it should not be observed by juxtaposing and judging from the illusion. When configuring the fresh ink, the dark ink should be added gradually, avoid adding too much at one time, and then remedy with a large amount of light ink. At the same time, the hue of the mixture should be reduced as much as possible. The more hue, the greater the gray scale.

In addition, attention should also be paid to the color change before and after drying. For example, on a light-colored substrate with a large amount of ink absorption, the dried ink is often light; the three-phase color difference between the wet state, the dry state, and the foaming state of the foamed ink is large; After the ceramic ink is fired, the hue changes; the white ink turns yellow after being heated. Such a rule of discoloration requires the printer to accumulate experience and samples in practice and make their own color standards.

The color deployment of screen printing ink (printing material) is a link that can not be ignored in the production process of silk screen printing. The basic principle of deployment is inseparable from the basic principles of additive coloration and subtractive coloration of colorants.
The three primary colors of the colorant are mixed in an equal amount of any two colors, and a certain color phase of the three primary colors of light can be generated. These three colors are called the inter-color (or second-time color) from the perspective of color, such as the green color formed by the mixture of yellow and cyan, which is the inter-color. The hue produced by the mixture of inter and inter-color is called the polychromatic (or third-time color). The mixed color and complex color of the three primary inks are shown in Figure 3-60.

2. Ink-toning method. The so-called color matching is to use two or more colors, or in addition to the main color palette, and then use a small amount of color adjacent to form a combination of colors. When the color inks are used before deployment, the color to be prepared on the color sample is first exposed separately, and the original (or as it is) color is determined to be the primary color, the inter-color, or the double color. If it is a multicolor, it needs to distinguish the ratio of the main color and the auxiliary color. Secondly, it must be based on the color tones specified in the manuscript, sample debugging, to be compared with the manuscript, the color difference is small or equal, before a large number of deployment, and the time is short, the amount of adjustment should be appropriate. Too few adjustments will cause work stoppages, and the ink will have a different hue, which will affect normal production. Too much will cause unnecessary waste. Toner transfer is usually performed where light is stable or where light does not directly shine.

There are three points to pay attention to in screen printing inks: a. When ink is mixed, ink with different colors should be added as little as possible. The less the type of ink, the better the mixing effect. b. With the principle of “from shallow to deep”, besides formulating light-colored or vivid colored inks, care should be taken when the hue is close to the template. Different manufacturers of ink, it is best not to mix calls, as far as possible using the same manufacturer of different colors of ink for color, otherwise it will produce uneven color, in severe cases, there will be condensation and make the ink scrapped. c. Some screen printing inks are dried by drying. Light-colored drying is lighter than unsealed, darker darkness after drying. In addition, it is easy to overlook the problem of whether the hue of the ink is different between before drying and after drying during printing. In general, through the natural drying (solvent evaporation type ink), the substrate is plastic, metal, paper, glass, etc., the color does not change; but if the ceramic used color, due to burning oxidation after the color Can only be color-tuned by experience. For screen printing inks that are dried by thermosetting and light-curing, the color changes in depth, as mentioned above. When the amount of ink is large, you can use the ink adjuster to complete the color adjustment in a short time.

The original ink color is mixed in different proportions, and many colors of ink can be dispensed, as exemplified in Table 3-15.

Table 3-15 Ink Color Formula Examples

Primary color synthesis color reproduction product Red Yellow Green 0 50 50 0 : 1 : 1 Green 50 0 50 1 : 0 : 1 Blue Violet 50 50 50 1 : 1 : 1 Black 25 75 0 1 : 3 : 0 Dark Yellow 0 25 75 0:1:3 dark green 75 25 0 3:1:0 orange red 0 80 20 0:4:1 apple green 100 25 25 4:1:1 red brown 25 25 100 1:1:4 dark green

The deployment of light ink is generally based on white ink, with appropriate color inks. Such as light blue, mainly white ink, slightly blue (cyan); light red, mainly white ink, slightly increase red; gray, mainly white ink, slightly black; silver gray, mainly white ink, slightly Add silver paste and add a trace of black ink. For the preparation of light-colored screen printing inks (printing materials), white ink should be added as little as possible, because the white ink has a large activity and is liable to cause discoloration in other colors.

In order to adjust ink, silk screen workers must do the following: a. Understand the various specifications and performance of inks; make the inks that they are suitable for production needs. b. Master the basic knowledge of colorology, and use it freely in the adjustment of ink. c. Analyze the printing color and technology, find out the color sequence of multiple colors, so as to avoid wrong color sequence, miscible two colors, and color change. d. Also pay attention to the color of the ink when adjusting the brightness of the ink, requiring a large brightness as much as possible to the original color to deploy, or easy to make out of the ink "gray", reducing the original color brightness. 3. Adjustment of printing ink suitability. Usually the factory screen printing ink, the viscosity is slightly larger, the user should use the appropriate solvent, thinner, surface according to the characteristics of the printing image, the number of screen mesh, printing speed, workshop temperature, substrate surface tension and ink absorption properties Active agents, viscosity-reducing agents, etc., make comprehensive adjustments to the ink's viscosity, surface tension, flowability, and drying speed. Such as screen printing thin lines and dots, the ink should be slightly smaller, the drying speed can be slightly slower; coarse screen printing, the viscosity should be slightly larger, the drying speed can be slightly faster; high-speed printing, the flow is slightly larger, the drying speed can be Slightly faster; when the temperature of the workshop is high, the drying should be slightly slower and the viscosity is slightly greater; the surface tension of the substrate should be small, and the surface tension of the ink should also be smaller; when the ink absorption of the printing surface is strong, the fluidity and surface tension of the ink can be large. Some, the drying speed can be slower. Appropriate adjustment techniques also rely on practical experience.

Reprinted from: Screen Printing