A: it is wrong to add diluent before mixing, because the viscosity of ink will decrease and become thinner after external force (such as mixing), so any ink must be thoroughly stirred before viscosity adjustment after opening the tank.
3. What is the function of solvent in solvent ink?
Answer: ⑴ dissolve the resin in the ink to make adhesive.
(2) disperse pigment and dissolving agent in ink to improve printability.
(3) dissolve and expand the substrate to improve the adhesion between ink and substrate.
(4) adjust the viscosity to improve the printability of the ink. (5) adjust the drying speed to meet the requirements of screen printing environment.
4. If there is no problem with ink quality, what are the causes of bubbles in the process of screen printing? How to solve it?
Answer: Reason and solution: ⑴ the viscosity of the ink is not right, it must be diluted. (2) the printing speed is fast, the screen distance is large, and the bubbles are pulled out because the screen bounces away from the substrate too fast. (3) if the wrong solvent is used, the miscibility with the ink is poor, so the special solvent of the ink must be used. (4) the use of fast drying solvent at high temperature and low humidity results in the appearance of bubbles on the surface conjunctiva. (5) the surface of substrate is not easy to be wetted. (6) ink expired.
5. What are the consequences of the uneven tension of the mesh?
Answer: ⑴ some places have thick ink layer, some places have thin ink layer and uneven thickness. (2) the pattern text is distorted. (3) local image and text may be blurred. (4) during dot printing, the dot will be deformed or misplaced, causing color deviation.
6. According to what is the net distance adjusted?
Answer: ⑴ it is mainly adjusted according to the tension of tension net. If the tension is large, the net distance will be small, otherwise it will be large. (2) adjust according to the size of the net frame, that is to say, the large net distance of the net frame is also large.
7. What is the effect of the mesh distance under normal tension?
Answer: ⑴ first of all, if the screen space is large, the scraping pressure of the scraper will be large, and the screen is prone to premature aging (large screen tension loss). (2) the mesh distance is small, and the mesh cannot be snapped away from the workpiece immediately, which makes the pattern dirty. Therefore, when the screen has a certain tension, it must be ensured that the scraping pressure of the scraper is the minimum and the screen can immediately spring away from the workpiece.
8. Why different types, different uses, different suppliers of ink must use different solvents? When the solvent is misused, what are the consequences?
Answer: because no ink is omnipotent, there are many kinds of substrate materials, so when choosing ink, the binder resin in the ink must be compatible with the substrate (workpiece) material, otherwise it will affect the adhesion, because the solvent in the ink is used to dissolve the substrate, so the ink can be firmly combined with the workpiece. Due to the different resin in the ink, the solvent is also different. If it is misused or misused, the following conditions will occur: ⑴ it will affect the color of the ink; ⑵ it will affect the comprehensive performance of the ink, such as: the adhesion is reduced, the solvent resistance is poor, the silk screen adaptability is not good, etc. (3) serious ink caking will lead to production scrap, etc. So all kinds of inks have their own special solvent, can not add and wrong.
9. Solvent ink solvent is divided into fast dry, medium dry and slow dry, these types are used in what circumstances? Answer: the drying speed of solvent is determined by the evaporation (volatilization) speed of solvent itself, and the evaporation (volatilization) speed is determined by their boiling point.
Fast drying solvent: boiling point is generally 100 ℃ 150 ℃
Medium dry solvent: boiling point is generally 150 ℃ 200 ℃
Slow drying solvent: boiling point is generally above 200 ℃
All kinds of solvent are not a single variety of solvents, they are mixed by several solvents, so as to control the drying speed of ink. Therefore, the automatic screen printing machine generally uses fast drying solvent, while the manual screen printing machine uses slow drying solvent in the case of high temperature and low humidity, and uses medium drying solvent in the environment of air conditioning and humidity control. If the wrong solvent is used, it will result in blocking and moire; the material will be corroded and cracked, so it is very important to choose the appropriate solvent.
10. What is the thixotropy of ink and what is its function?
A: the ink will be thickened and viscosity will increase after a certain period of time. However, it will become thinner and viscosity will decrease after agitation. This is the thixotropy of the ink. Thixotropy of ink is beneficial to screen printing to improve printing accuracy.