Remain as based on the quality of solvent based inks for printing the same, a good water offset printing ink must achieve VOC zero emissions; must has good printability; to printing on various substrate materials on the surface; also hope that the printing ink of the relatively low cost. 

The water-based ink for offset printing can produce such as changing the lithographic printing roller engraving, printing machine, printing machine maintenance, drier replace change. Similarly, the substrate material will strongly affect the ink printing effect, especially for low surface tension of the substrate such as plastic film materials and coated paper surface printing. And for the non coated paper, ink and may even result in a paper of deformation and curling, these problems for solvent type of offset printing ink is not exist. 

The importance of water pH value of offset printing ink: 

Comparison of water-based and solvent based lithographic printing inks, in scraping knife from the lithographic printing ink hole scrape off the excess ink process by solvent based ink printing lithographic printing process as much as possible to reduce solvent volatilization, in nano imprint lithography process is completed, ink is transferred to the substrate material, and then slowly to form a film of ink, in the process of solvent ink must be before the ink film adhesion on the completion of the process of evaporation, quickly reached the monlchamus membrane drying. In the water-based ink, the organic solvent is replaced by a certain percentage of water, a solvent and a volatile amine, which are necessary for the neutralization of the acidic resin. Due to a slow water volatile, so there is no ink in a printing plate ink hole volatile drying, but there are printing after drying, so the choice of ink in amine, for pH adjustment and control the ink viscosity is as important. Because during the imprinting process completed before amine solvent of premature release caused the pH value decreased, resulting in the resin was dried in the lithographic printing roller inking hole. In addition, water and solvent systems are unable to re dissolve the resin, which is different from the solvent based inks. Therefore, it is impossible to re dissolve any pH value. In the lithographic printing to very careful control of pH value, because of inking hole was slowly blocked until it is completely blocked - caused by ink pH decline. This is a very serious problem, will result in printing work unable to proceed. 

The importance of surface tension of aqueous lithographic printing inks: 

At the same time, the surface tension of ink and wash is an unavoidable factor, which is completely different from the solvent based inks. Compared with the solvent based inks, the ink surface tension is much higher; and surface tension is too high will cause the ink cannot very good wetting substrate material surface and lithographic printing roller inking hole, it will result in printing ink film is not uniform; due to the surface tension of the ink, ink film will be contracted state is formed on the substrate surface, resulting in ink film shows a distinct network, but also cause ink cannot be evenly from the holes in the ink transfer to the substrate surface. 

But the surface tension can be reduced, it should be careful to select the appropriate surface active agent or a small amount of alcohol. Although the development version of printing ink to pay huge labor, but in maintaining the printing quality of the printing ink (like the printing quality of solvent based inks), prevent ink in offset printing VOC emissions is still a difficult challenge.