Excellence in Ceramic Printing

Excellence in Ceramic Printing A comparative study conducted recently has demonstrated that naphthenic oil performs very well as a liquid carrier for ceramic ink formulations used in inkjet printers. This is good news for the ceramic industry, where inkjet printing technology is widely used to apply patterns to tiles. As inkjet printing technology, which offers many advantages compared to traditional methods, rapidly becomes the leading technology in ceramic tile decoration, the development of inkjet inks with the correct chemical and physical properties plays a key role. Inkjet inks for ceramics must meet a wide range of requirements not only with their performance during the spray cycle, but also with their performance before and after the printing stage. Stability during storage and transportation, where preventing sedimentation and agglomeration is important, is crucial. Similarly, thermal stability at working temperatures used in processes and low evaporation properties are essential. The ink must pass easily through filters and not clog spray nozzles, and it is also expected to perform as desired on unfired ceramic substrates. For solvent-based inkjet printers, ceramic ink consists of solid particles such as pigments, liquid carriers and additives. The carrier, which comprises approximately 50% of the ink by weight, plays a critical role in the chemical and physical properties of the ink and greatly influences the behavior of the ink during droplet and dot formation. Ether and ester are commonly used carriers in ceramic inks for inkjet printers, but a special naphthenic oil is also an accepted alternative. Nynas conducted research together with an institute to compare the performance of these different carriers in ceramic ink for inkjet printers. Several different products from Nynas' naphthenic oil product family were used in ink formulations alongside ether and ester, and these were subsequently put through a comprehensive test program. The results showed that a carrier's viscosity is a key property that greatly affects the fundamental characteristics of ceramic ink for inkjet printers. In addition to ether and ester, low-viscosity naphthenic oils also demonstrated excellent performance in ink formulations not only in terms of correct viscosity, density and dynamic surface tension, but also in terms of colloidal stability and printability before and after accelerated aging. • The colloidal stability of ink formulations was measured by examining the level of particle sedimentation and agglomeration. The less sedimentation and agglomeration, the higher the colloidal stability of the ink. Inks formulated with NYFLEX® 201B and NYTEX® 801 naphthenic oils exhibited less or equivalent sedimentation compared to inks made with ether and ester. All inks showed very low agglomeration (see Figure). • Inks prepared with the above carriers demonstrated excellent filterability through a 5 μm filter membrane as well as excellent printability. In addition to these, no significant change in printability was observed before and after aging in these inks; this demonstrated that the same level of stability with ether and ester could be achieved using NYFLEX® 201B and NYTEX® 801 naphthenic oils. • Due to the higher viscosity of NYTEX® 810, inks made with NYTEX® 810 showed less filterability compared to the other four carriers. However, higher viscosity tended to reduce the grinding time required during ink preparation. Therefore, NYTEX® 810 can be used together with other carriers to balance these physical properties and advantages. Higher stability in inks [caption id="attachment_145408" align="alignleft"] [/caption]                   Elvis Li Technical Advisor Chemical Manufacturing Industry Nynas Naphthenics