Some Issues to Pay Attention to in the Application of Alcohol Free Printing Technology

During a survey conducted at a large printing company in Guangzhou, it was observed that the company has achieved good results in promoting alcohol free printing. The use of alcohol free printing not only reduces printing costs, but is also environmentally friendly and can reduce a series of environmental problems caused by alcohol evaporation. Therefore, this article on alcohol free printing has been compiled to help everyone better understand and apply it.

The use of alcohol substitutes in non-alcoholic printing makes it easier to achieve ink water balance. By using a specific thickness of ink film that has not been diluted by alcohol to complete printing, higher quality printed products with fine dots and less emulsification can be obtained.

1. Alcohol substitutes

Alcohol substitutes differ from IPA (isopropanol) in several key properties, including viscosity, surface tension, pH value, and conductivity of the lubricant. Non alcoholic products cannot be applied to different printing machines at will. This requires close communication with printing operators and seeking the best fountain solution formula from suppliers.

In fact, there are various alcohol substitutes that can be used. They are all composed of one or more chemicals extracted from the chemical groups of ethylene glycol and ethylene glycol ether, and other additives similar to IPA are also added. And these formulas all attempt to completely replace IPA in the moisturizing solution and provide some unique performance. More importantly, the concentration of alcohol substitutes we use is much lower than that of IPA. Under the same printing conditions, a small amount of alcohol substitutes can achieve 10-20 times the effect of IPA containing fountain solution.

2. Lubrication solution viscosity

Adding IPA to the fountain solution will greatly increase its viscosity, but many alcohol substitutes have little or no effect on viscosity. Due to the decrease in viscosity of alcohol substitutes, less fountain solution is measured by squeezing or using measuring rolls on continuous contact fountain rolls, which requires an increase in the speed of the fountain rolls. This has led many printing operators to mistakenly conclude that more water must be used when printing with alcohol substitutes. In fact, the solution to improve viscosity to a certain extent is to cool the lubricant.

3. Surface tension

The ability to quickly wet the printing plate and form a thin water film are two key requirements for offset printing, which are mainly determined by the surface tension of the plate wetting solution. It is generally believed that low surface tension plate lubricants can be better used in high-speed printing, but there are also reports in Europe to the contrary. It is understood that current alcohol substitutes can achieve the low surface tension of IPAs that printing operators are accustomed to.

The surface tension of pure water is 72 × 10-3 n/m. In the plate solution, the concentration of alcohol is 10% to 25%. Reducing the surface tension to reach (35-45) × 10-3 n/m can quickly form a continuous thin film in the plate solution, covering the entire printing plate. And non-alcoholic toner uses surfactants and solvents to reduce surface tension.

Surfactants or surfactants are organic chemicals that tend to concentrate at the interface due to their polar molecular structure. Under normal circumstances, they are located at the interface between the fountain solution and air, as well as between the ink and air. In high-speed printing, these interfaces