Ink drying is too slow, it’ll result in print dry not enough, ink sticks to the guide roller,the print loses its luster,but also affect the overprint effect, there will be happen print quality problems.
If inking dry is too fast, it will transfer poorly, which will easily lead to blocking, imprinted edges appear jagged,ink dries to printing plate surface. If the water-based ink dry is too fast,when printed screen version, it will cause the print surface scratches, because in the printing process, ink has not penetration into substrate surface already dried causing ink suspension in the printing surface, can wipe off.
Ink drying speed in the printing process to be moderate, such as slow drying, drying process is faster, this is a contradictory printing process. So ink performance and the ability to dry equipment on presses determines printing machine production. In turn,the higher printing speed can shorten ink exposure time in the air.
Qingyi Y-WT series polyurethane high elasticity screen printing ink color card.
For using ink, has the following suggestions:
1. Appropriately increase the ink pH to reduce printing process drying speed, without affecting the drying printing tools speed, pH number is generally controlled at 8.5 ~ 9.5.If drying too fast, you can add stabilizer to control the pH number above 9, but cant exceed 9.5, or ink properties will change. Ink surface tension is low, cable version easy to block version, drying will become more slow.
2. In case without affecting printing speed, try to make ink drying in the printing process a little slower. Can be adjusted by adding slow drying agent. Different manufacturers ink need to add different amount slow-drying ink,generally not more than 5%.After adding slow-drying agent ink will become thicken, pH number will be reduced. Therefore, adding slow-drying agent at the same time need to join water and stabilizers to control ink viscosity and pH number.
3. Enhance the oven air convection speed, can significantly accelerate the print drying speed. Because water-based ink contains a lot of water and alcohols, to enhance convection can reduce the relative humidity in the oven, accelerate solvent evaporation printing tools.
4. Add slow-drying agent can solve printing scratches and varnish surface sticky dirty. Ink drying too fast will cause ink doesn’t enter infiltration stage dry solid substrate surface, resulting in insufficient adhesion, ink layer is easy to fall off, when overprint or glazing, the latter color plate will be stick out previous color ink, for this can also adjust the color sequence or reduce ink viscosity.
5. Add slow-drying agent and speed, can reduce blocking phenomenon. Printing too slow will make ink spread on the plate,resulting in network adhesion, however, ink dry is too fast,it’ll make ink can not be fully transferred, resulting in outlets around accumulation ink, cause blocking phenomenon.
6. Printing products with a larger amount of ink, should try to use high-density ink, A high number of anilox roller, which conducive to the print drying, can also reduce watermarks phenomenon.