Polymer encapsulation of submicron-sized TiO2 and its effects on the whiteness, reflectivity, hiding power, and dispersion stability during inkjet printing

• Published in: Polymer journal Vol. 55; no. 5; pp. 607 - 616
• Main Authors: Hasan, Md. Kamrul, Enomoto, Kazushi, Kikuchi, Moriya, Narumi, Atsushi, Takahashi, Shigeki, Kawaguchi, Seigou
• Format: Journal Article
• Language: English
• Published: Tokyo Nature Publishing Group 01.05.2023
• Subjects: Aluminum oxide; Brightness; Drying; Electron microscopy; Emulsion polymerization; Encapsulation; Inkjet printing; Inks; Microscopy; Polyethylene terephthalate; Polymers; Polymethyl methacrylate; Polystyrene resins; Reflectance; Stability; Styrenes; Thickness; Titanium; Titanium dioxide
• ISSN: 0032-3896; 1349-0540
• DOI: 10.1038/s41428-023-00756-x

We studied the effects of polymer encapsulation of 290-nm-sized Al2O3(Al)-coated titanium dioxide (Al-TiO2) particles on the reflectance and hiding power of an inkjet image printed on a polyethylene terephthalate (PET) film. Two different polymer shells with thicknesses of 20–30 nm included a poly(methyl methacrylate) (PMMA) shell and a multilayered shell comprising PMMA and poly(styrene) (PSt) (PMMA/PSt). These hybrid particles were successfully prepared by using seeded semicontinuous emulsion polymerization of methyl methacrylate (MMA) and styrene (St) in the presence of a thermoresponsive polymerizable nonionic surfactant, NE-10. The inkjet printing inks were formulated and inkjet-printed on a PET film, and their brightness (L*) values were measured. The L* values of the inkjet images printed with the PMMA- and PMMA/PSt-encapsulated Al-TiO2 inks were greater than those of bare Al-TiO2 at the same TiO2 concentration. This increase was thought to result because the polymer-encapsulated TiO2 particles did not agglomerate and were well spread and dispersed during the drying process, as evidenced by scanning electron microscopy and transmission electron microscopy observations. The dispersion stability of the ink was also increased by polymer encapsulation. We conclude that the polymer encapsulation of TiO2 particles is a promising method for enhancing the whiteness and hiding power of inkjet printings by maintaining dispersion stability during the printing and drying processes.We studied the effects of polymer encapsulation of 290-nm-sized Al2O3(Al)-coated titanium dioxide (Al-TiO2) particles on the reflectance and hiding power of an inkjet image printed on a polyethylene terephthalate film. Two different polymer shells with 20–30-nm thickness of a poly(methyl methacrylate) (PMMA) shell and a multilayered shell of PMMA and poly(styrene) (PSt) (PMMA/PSt) were prepared using seeded semicontinuous emulsion polymerizations. The brightness (L*) value of the prints from the PMMA- and PMMA/PSt-encapsulated Al-TiO2 inks increased compared to bare Al-TiO2.