What are the ten reasons why the ink is not always scraped clean in the printing process?
Ink is an important material for printing, it is essential in the printing industry by printing the pattern text, etc. on paper. In the printing process, the ink scraping is not clean troubled many manufacturers, today and share with you the printing of ink scraping is not clean for 10 reasons.
Ink
Ink is a uniform mixture of colored bodies (such as pigments, dyes, etc.), linking materials, filling (filling) materials, additional materials and other substances; can be printed and dried on the printed body; is colored, with a certain degree of flow of the slurry adhesive body. Therefore, the color (hue), body and bone (thinness, flow and other rheological properties) and drying properties are the three most important properties of ink. They are many types, physical properties are also different, some are very thick, very sticky; while some are quite thin. Some use vegetable oil as the linker; some use resin and solvent or water as the linker. These are based on the object of printing that the substrate, printing method, the type of printing plate and drying method to determine.
01 ink viscosity is too high
When the ink viscosity increases, its surface tension increases accordingly, and the mutual force increases, so that the squeegee in contact with the ink in the process will increase the impact of the ink on the squeegee, destroy its balance point, resulting in the squeegee can not be empty part of the plate roller ink completely scraped clean, directly affecting product quality.
02 scraper pressure is too small
Under normal circumstances, just when the machine is turned on, the scraper pressure is often set very small, as the machine speed increases, the impact of the ink on the plate roller on the scraper will increase with the machine speed, the destruction of the original balance point, directly resulting in scraping not clean.
03 ink into the moisture or use too long
Ink in the use of a longer period of time, on the one hand, in the long cycle process will cause the pigment in the ink constantly precipitation, so that the composition of the ink changes, on the other hand, the water vapor in the air will be due to the evaporation of solvent and solidification, into the ink, the same changes in the composition of the ink. Thus changing the overall performance of the ink, so that the ink scraping performance is greatly reduced, directly increasing the difficulty of scraping the net scraper, resulting in the generation of scraping not clean.
04 solvent is too fast dry or slow dry
Mixed solvent is too fast dry, in addition to making the ink viscosity in a short period of time, but also make the ink stick in the spare part of the roller, due to solvent evaporation too fast, the ink adhering to the roller will be gelatinous, in the roller after the scraper, due to the gelatinous ink adhesion force is high, the scraper can not run a week in the case of the roller will be scraped down, thus directly brought to the printing substrate, resulting in scraping unclean generation.
The solvent itself evaporates very slowly, causing the spare part of the ink on the plate roller can not dry solid in time on the surface of the plate roller, its state is similar to the dot part of the ink, so that when the printing substrate through the plate roller, the spare part of the ink on the plate roller is easily transferred to the printing substrate, resulting in the generation of scraping unclean.
05 plate rollers used for too long
Due to the use of a long time, the surface of the plate roller will be due to the force of the scraper and wear, its surface will become increasingly smooth, resulting in the affinity between the ink and the plate roller more and more strong, directly increasing the scraper scraping net difficulty, resulting in scraping clean.
06 scraper assembly is too soft, the angle is too flat
Scraper assembly is too soft, the angle is too flat, due to the role of air pressure, will make the scraper in the plate roller surface that is scraping the ink point bending state, resulting in the way scraping ink is not “point” relationship, but “surface” relationship, so that can not be effective on the spare part of the plate roller That is, no network part of the ink scraped down, resulting in the generation of scraping not clean.
07 plate roller assembly is not the center
Plate roller assembly is not the center of the phenomenon, under normal circumstances within 10 silk jump will not affect the color and product quality. When the plate roller from the oval diameter of the longer side of the operation to the oval diameter of the shorter side of the instant, the distance instantly become longer, because the squeegee is external force acting on the plate roller, so there is a time difference in the process of conversion, the formation of a period of time that the pressure of the instantaneous squeegee relative reduction, so that due to the jump of the plate roller caused by the pressure of the squeegee in an edition of the pressure of a tight one loose, resulting in a local scraping unclean phenomenon.
08 solvent problem
A, because the solvent is added to the use of the ink, so the solvent into the water will directly damage the overall performance of the ink, resulting in scraping not clean.
B, improper solvent ratio, directly cause the ink to dry fast or slow dry, resulting in scraping not clean.
C, the solvent itself has impurities, such as purity is not high, the water content is high.
09 ink does not circulate
Do not circulate the ink on the one hand will make it difficult to control the viscosity, on the other hand, because the ink has thixotropic characteristics, in the non-circulation will reduce the performance of the ink, in addition, due to the non-circulation will also cause the ink tank ink surface crust, directly increase the crust dry ink adhering to the opportunity to the plate roller, resulting in the phenomenon of scraping not clean.
10 stirring the problem of the ink stick
As the raised part of the surface of the ink stirring rod after the use of more or less adhered to some ink, with the use of the number of times, the amount of ink increases, when the solvent evaporates completely, there is dry ink left. In the next use process, because the ink in the ink tank can not be completely dry ink wetting the raised part of the surface of the stirring bar, resulting in gelling strong ink in the stirring bar with the roller operation process transferred to the surface of the roller, due to the adhesion and strong, so the scraper can not run a week in the case of the roller will be scraped down, thus directly to the printing substrate, resulting in the generation of scraping unclean, this phenomenon is especially no dot Part is more obvious.
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