Introduction To Better Operation Of Flat Screen Printing Machin
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Posted by licheng flatprinter - Filed in Business - #Stenter #Flat Screen Printing Machine - 821 views
The drying process of Stenter ink
The drying process of the ink consists of two steps. The first step, oxidation, is a process through which oxygen interacts with the oil in the ink and the mixed ink to form a solid. The second step is absorption. After this process, the solvent enters the paper and allows oxygen to touch the oil or mixed ink. If the speed of the solvent entering the paper or coating is not fast enough, it will reduce the reaction speed of oxygen, oil and varnish, and eventually extend the dry moment.
With this in mind, let us pay more attention to the boring process. When the ink starts to print on the substrate, the solvent in the ink will enter the gaps in the fibers or coatings of the substrate. The pigment remains in the dry oil part, which fixes the pigment on the printed surface. But this is not completely boring yet. Because of the loss of the solvent, the ink film becomes very viscous. In this way, the ink loses its fluidity and stops there to prepare for change. Following the loss of solvent, oxygen reacts with oil, and the resin begins to dry. During this period, the ink appearance is fixed and will not transfer to another sheet of paper in the stack. However, the ink at the base of the ink film still adheres to a certain liquid state. Depending on the composition of the ink, the thickness of the printing ink film, the properties of the paper or other raw materials, and environmental conditions, it may take two minutes to more than one and a half hours for the ink to be completely fixed.
After printing, oxidation occurs in alkyd resin or dry oil, and perhaps also in resin. This polymerization result constitutes the three-dimensional, network structure of the chemical binder. Oxygen reacts with all the oils and resins in the ink to convert the liquid material in the ink film into a solid, so that the ink is completely dry. If you leave the linseed oil open, the same response will occur. Oxygen will react and intersperse with the linseed oil, eventually hardening.
A paper or coating with a very tight appearance will slow the penetration of solvents. Therefore, there will be solvent residues in the ink, and it will dry up with the reaction between oxygen and oil and varnish. Of course, this will also add boring moments of ink.
In order to speed up drying, use a "drying agent" in the ink to speed up the oxidation process. The two most widely used and longest used desiccants in industry include the following:
Cobalt: can speed up the process of boring appearance (fixed). Since cobalt is blue, it becomes brown in the dry period, and it is easy to fade the white color. Moreover, it is easily soluble in organic acids, so acid fountain solution with too low PH value (below 4.0) has an effect on it.
Manganese: It can speed up the internal drying process and is a more powerful drying agent than cobalt. This desiccant is brown, but it has less effect on white than cobalt, and it does not easily enter the fountain solution.
In the process of printing operation, a mixture of these desiccants is usually used to speed up the external and internal desiccation at the same time so as to complete the desiccation process.
According to the following part of the process, printers can overcome the boring question of ink:
1. Review the work with the ink supplier before printing, including the paper used. The best solution to boring questions is to prevent them. All paper is different. For example, the dryness of ink on newsprint is completely different from the dryness of ink on papers like SpringhillOpaqueSmooth.
2. When printing on paper with a fine surface, avoid using soybean oil-based ink. Soybean oil is semi-dry (slow) oil.
3. Keep the pH of the fountain solution within the range of 4.0 to 5.0.
The higher the acidity (the lower the PH value), the slower the drying process of the ink.
4. When printing a large area of solid land, use a blending oil including desiccant or a clear scale for overprinting.
5. Use the recommended amount of desiccant for the ink being used. Too much desiccant will plasticize the ink so that it is not boring
6. Mixing additional desiccant in the fountain solution can improve the desiccation function of the ink. GrafOSiec is an example of an additional desiccant, which can be added in an amount of 1% to 3%.
7. Make the paper stack lower at the receiving end of the printer.
8. Use large particles of dust to help separate the paper after printing, and allow more oxygen to enter and react with oil and resin.
9. Let the supplier add the strength of the ink, so that it can be printed with a thinner ink layer, which can be fixed and boring more easily.
10. Since the temperature of the printer or paper may be too low and will delay ink drying, pre-process the paper before printing.
11. Remember that the ink composed of ReflexBlue extends the boring moment. Comment with the ink supplier.
12. There must be a dull moment of satisfaction before running or changing jobs.
13. Use infrared drying to speed up ink drying.
14. Remember that the ink used for film printing will be fixed and hardened on the tough film for a few hours.
Moreover, the best action plan for Flat Screen Printing Machine is to review the work and paper to be used with the ink supplier. Some ink dryness is suspected to be the result of improper carriers, which result in a low oxidation process or a lack of usable catalysts. The oxidation rate can be increased by adding more oil or alkyd resin in the catalyst, or by using thoroughly dry materials, such as linseed oil or tung oil, instead of semi-dry oil, such as soybean oil.