DEFINING OF TIME-DEPENDENT CONTACT ANGLE OF LIQUIDS ON THE PRINTING PLATE SURFACES

摘要

The wetting properties of nonprinting and printing areas on a lithographic printing plate have a key role for achieving high quality printing properties. The wetting characteristics of printing and non-printing areas of the offset printing plates were defined by measuring the spreading contact angle of standardized liquids. As the printing process is dynamical, the contact angle was measured as a function of time. Results have shown that contact angle values and consequently surface free energie values of non-printing areas (polar characteristics) have been significantly changed during the time period of measurement. This research has proved that dynamic contact angle of liquids has a specific and most important role in determination of wetting properties of the investigated surfaces.