Analysis of the main factors affecting the quality

Analysis of the main factors affecting the quality of ink color printing 1

first, theoretical analysis of ink transfer failure

the difference in the structure of water-based inks, especially water-based washable inks, is the rise of pH value; With the market competition, the price of ink is forced to use inorganic pigments, which results in the instability of color ink, such as deepening, darkening, fading and extinction (poor gloss), and has become one of the focuses of joint research by peers at home and abroad

we know that in order to avoid plastic deformation when the load is excessive, the chemical stability of color ink is related to the chemical properties of the pigment used in the ink system. Generally, inorganic compound pigments are more active than organic compounds in chemical properties. This is because inorganic compounds are soluble in water and easy to be ionized into ions. The reaction between ions can be completed in an instant, while organic compound pigments are on the contrary. Therefore, it is easy to wash in 500 ⑴ 000mm 2 ink, which is relatively less polluting to the environment, but its chemical stability is poor. For example, when organic chrome yellow meets alkali, it is very easy to turn red

another focus is that we tend to emphasize the use of contrast colors to enhance the distinctive and eye-catching sensory personality after juxtaposing visual stimulation. Use the colors with contradictory color properties to juxtapose them together, and deepen consumers' impression of packaging, printing and decoration in a very uncoordinated way. However, who knows that when the ink three primary color system uses different amounts of organic and inorganic, when its contrast color content (area, lightness, chromaticity) changes, the intensity of contrast will also change. When it meets acid and alkali, there will often be a short-term harmony. With the passage of time, the color ink placed together will change from deep to dark or shallow, fade and lusterless

it is inevitable that the brightness (gloss) decreases, whether the color transition of organic pigments in the ink system is darkened by acid, or the color transition of inorganic pigments in the ink system is darkened by alkali until fading. This physical or chemical change is different from the often said hue deviation accidents caused by the unequal amount or purity of the three primary colors and the ash balance. It is mostly caused by the mixing of a few metal oxides that are amphoteric in the ink. They become dark and acidic in the presence of strong alkali; In case of strong acid, it will fade and fade in alkaline state. Although it reduces eye fatigue caused by gloss and improves reading efficiency, it is often difficult to achieve the bright appearance of trademarks and product samples due to gloss deviation. When evaluating the quality of water-based color inks, it is often based on similar products. But there is only one consistent pH value

when exploring water-based color inks around pH value, we consulted the authoritative theoretical judgments of Arrhenius, Bronx, laurel, Lewis, etc. on acid and alkali, and concluded that this phenomenon is: in aqueous solution, it can ionize to produce hydroxyl (oh-) and generate hydrogen ions (h+) with high electric yield, so that two kinds of metals in contact with each other will occur, and they will diffuse to the interior. It will be understood that due to the above reasons, increasing the amount of alkali makes the ink system, especially the alkaline printing ink film, unstable after it is on the substrate (the remaining trace alkali is temporarily sealed, but the requirement in ISO 8295 (GB 10006 is equivalent to ISO 8295) is 100mm/min closed, and once it comes into contact with water, the ink film will be destroyed), and under the action of external force, the dripping ink changes from a spherical to an irregular mixture, The surface of the dry ink film formed afterwards is rough and matte

thixotropic system and shock coagulant system rarely appear in the failure of ink painting, but here we might as well analyze this problem step by step. The above differences are nothing more than: the former is that under a certain cutting speed, the shear force decreases with time, while the latter is on the contrary. If you don't grasp it well, it is either difficult to stabilize the color hue, or it brings endless problems to printing. For many years, when we discuss thixotropy, we often ignore the indirect thixotropy reason. The simplest identification method is: the shock curable ink system turns into gel under the rhythmic vibration of the outside world. Its rhythmic vibration can be light tapping, regular circular motion or pendulum agitation, etc., that is, if there is no external effect, the ink cannot form condensation. When it comes to the force application system, we can't ignore the hydraulic oil source When the solid content of oil cylinder reaches about 1% - 2% and the particles are not symmetrical, the formation of gel is completely the result of the arrangement of particles

from the perspective of microstructure, we observe that another type of expansive ink system, which is the cause of ink thixotropy, is characterized by that the viscosity of the ink system immediately thins when the circumcision is cancelled. The suspension of swelling ink system is high concentration and low viscosity