Stability of water-based pigment inks Development Department of Company Y, an ink manufacturer
Address environmental switching issues
Improved dispersion and vivid colors
Company Y is being asked by a packaging manufacturer to improve its prototype water-based pigment ink, and is busy trying to respond to the request. The ink used for package printing and date printing has issues with the dispersion stability of the pigment during storage, causing a gradual increase in viscosity over time and a deterioration in color characteristics (saturation and transparency). In addition, there has been an issue with printer nozzles becoming easily clogged during printing, especially for inkjet printing.
* This is a hypothetical example posted as a reference for those with similar challenges
Challenges
The pigments clump together, clogging the nozzles and leaving the color characteristics unsatisfactory. This problem needs to be solved quickly...
The client who made this request was looking to switch from conventional solvent-based inks to water-based inks for environmental and safety reasons, and just as they were about to do so, these issues came to light.
Mr. S from the development department, who was put in charge of making improvements, decided to focus first on identifying the cause of the pigment dispersibility issue.
"After testing, we found that the anionic pigment particles we were using were more hydrophobic than we had initially anticipated, making them difficult to disperse. As a result, even a slight drying process caused the pigment to clump together, making the nozzles more likely to become clogged. Similarly, the lack of color characteristics was due to poor pigment dispersion, which resulted in a lack of vividness," Mr. S recalled, looking back on the situation at the time.
Mr. S consulted with other members of the development department and decided to change the additives to improve the dispersibility of the pigment. However, when they evaluated additives such as polymers that Company Y had a track record of using, the improvement in dispersion stability was insufficient.
Mr. S also contacted trading companies with which he did business to try to gather information on other additives that might be of use. However, he was unable to find any information that could lead to improvements. This situation only made Mr. S and the rest of the development department increasingly anxious.
Key Challenges
The hydrophobicity of the anionic pigment particles used is stronger than initially expected, making them difficult to disperse.
As a result, even a slight drying process caused the pigment to aggregate, making the nozzles more susceptible to clogging.
In addition, poor pigment dispersion resulted in a lack of vividness and poor color characteristics.
The improvement of dispersion stability using additives such as polymers that have been used before was insufficient.