Hydrophobicity and Elemental Composition of Laser­ Printed Toner Films

Laser-printed toner films on a polymer support were treated with alkaline (NaOH) aqueous solutions at elevated temperature (80-85° C). These toner films were examined with a sessile-drop contact-angle measurement technique in order to establish the hydrophobicity of the toner surface. Also, X-ray photoelectron spectroscopy (XPS) was used to ana­ lyze changes in elemental composition ofthe toner surface. The surface of laser-printed toner film was found to be hYdrophobic. Although the toner used is mainly composed of styrene-acrylate copolymer and styrene polymer, it was found that Si-containing organic compounds play an important role in es­ tablishing the wetting characteristics of toner sur­ faces. The advancing contact angle for water drops at the surfaces of untreated toner films was found to be from 105 to 115 degrees. The receding water contact angle was 57 to 67 degrees. The treatment of toner films at elevated temperature (80-85° C) using water or aqueous alkaline solutions led to a reduced hydrophobicity of the toner surface. Sodium hydroxide solutions were found to be more aggressive than pure water. The advancing con­ tact angle was reduced to a value of less than 90 degrees and the receding contact angle dropped to a near zero value when the toner film was contacted for 2 min with hot alkaline solution. XPS analysis of the toner film showed that Si-containing organic compounds havinga decreased C/O ratio as com­ pared to the original toner composition were ex­ tracted from the surface region.