1. Screen printing which five variables?
scraper hardness, network distance, printing speed, scraping pressure, ink adaptability.
2. Inks before the use of the diluent is not stirred on the right? why?
It is not right to add thinner before stirring, because the viscosity of ink will drop and thinning after external force (such as stirring), so after any ink is opened, it must be thoroughly stirred and then adjusted viscosity .
3. What are the effects of solvent in solvent inks?
1) dissolve the resin in the ink made of adhesive;
2) dispersing the pigment and dissolving assistant in the ink to improve the printability;
3) dissolve, swell the substrate, improve the adhesion of ink and substrate
4) adjust the viscosity, to improve the printability of ink;
5) mediation drying speed, to adapt to the requirements of silk screen environment.
4. If the ink quality is no problem, then the screen printing process in which the
bubble is caused by what? How to deal with it?
Causes and solutions:
1) the viscosity of the ink does not, must dilute;
2) scratch printing speed, network distance, because the screen from the substrate too fast and pull out the bubble;
3) with the wrong solvent, poor compatibility with the ink, it must be a special ink solvent;
4) in the case of high temperature and low humidity using fast-drying solvent, resulting in surface conjunctiva is too fast and bubbles;
5) As the substrate surface is not easy to wet state caused bubble;
6) ink expired failure.
5. Stretch tension will cause the consequences of uneven?
1) thick ink in some places, and some local ink thin, uneven thickness;
2) distortion of the pattern text;
3) local graphics may be fuzzy;
4) When the network printing dot distortion or dislocation, resulting in color cast.
6. What is the network distance adjusted according to?
1) is mainly based on the tensile tension adjustment, tension is a large distance from small, and vice versa;
2) According to the network frame size adjustment, that is, large-scale network box followed by large.
7. Normal tension under the size of the network will affect what?
1) the first network from the large, scraping the scraping pressure on the big screen is easy to premature aging (net tension loss);
2) the distance from the small screen can not be immediately bombed from the workpiece, so that pattern by dirty.
Therefore, the screen has a certain tension in the case, we must ensure that the process of scraper scraping scraping pressure in the screen and the screen can be immediately ejected from the workpiece.
8. Why different types of ink, different uses, different suppliers of ink must use
different solvents? When the solvent is wrong, what will the consequences?
Because there is no ink is a panacea, the substrate material variety, so the choice of ink, the ink in the connection material resin and substrate (workpiece) material to adapt, otherwise it will affect the adhesion, ink In the solvent is the role of corrosion of the substrate, so the ink can be combined with the prison prison.
Because the resin in the ink is different, so the solvent is also different, if misuse or misuse will appear the following:
1) will affect the fineness of the ink;
2) will affect the overall performance of the ink, such as: decreased adhesion, poor solvent resistance, screen printing is not good;
3) serious will make the ink caking resulting in production scrapped and so on. Therefore, all kinds of ink has its own special solvent, can not be added chaos and wrong.
9. Medium oil are classified as fast-drying, medium-dry and slow-drying. What are
the types of solvents used?
The drying speed of medium oil is determined by the evaporation rate of the solvent itself, while the steaming speed is determined by the boiling point of the solvent itself.
Quick-drying solvent: boiling point is generally 100 ~ 150 ℃;
In the dry solvent: boiling point is generally 150 ~ 200 ℃;
Slow dry solvent: boiling point is generally 200 ℃ above.
A variety of solvents are not a single species of solvent, they are mixed by several solvents, and thus control the drying speed of ink. So the general automatic screen printing machine, with quick-drying solvent; and hand-screen and in the case of high temperature and low humidity with slow-drying solvent; in air-conditioned and control the wet environment with the dry solvent. If the wrong solvent will produce blocking network, textured; material to be eroded and cracking, etc., so the choice of the appropriate solvent is very important.
10. What is the ink thixotropy, what effect?
The ink static after a certain time will have a thickening, viscosity also becomes larger, and stir after thinning, viscosity and smaller characteristics, this is ink thixotropy. Thixotropic ink is conducive to screen printing to improve the printing accuracy.
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