Universal Black Inks Based on New Polymeric Carbon Black Dispersions

Abstract

Carbon black is well established as the primary pigment in text black inks utilized in small office/home office (SOHO) desktop ink jet printers. Through innovations over the past 10–15 years, inks containing self-stabilized dispersions of surface-functionalized carbon black pigments have evolved as the main technology for such applications. Factors influencing this choice include text density and acuity, paper-to-paper (plain) image quality consistency, and versatility in ink formulation. Although these technologies set the industry standard, important limitations still exist; these include: (1) image smear on plain papers typically used in desktop printing, and (2) the lack of image gloss and durability on coated, glossy papers used for photo printing. These limitations have precluded the broadest use of inks based on self-stabilized pigments. This has been especially true for drop-on-demand thermal ink jet.This paper focuses on the question of whether it is possible to develop a universal or single black ink based on alternative carbon black dispersion technology that is able to meet the critical requirements of both plain (for text and graphics) and glossy (for photos) papers used in SOHO desktop ink jet printers.New polymeric dispersions comprising specific carbon black pigments and new polymeric dispersants (terpolymers) have been developed that can provide some of the important performance characteristics of self-stabilized carbon black dispersions used in the ink jet industry. Random terpolymers of benzyl methacrylate (BzMA), an additional hydrophobic monomer containing twelve or more carbon atoms, and methacrylic acid (MAA) have been used as effective dispersants with Black Pearls®700 carbon (Cabot Corporation). Certain inks formulated with these new dispersions were found to be suitable for a variety of ink jet applications and appear to overcome many of the deficiencies currently limiting the more general use of black inks that rely upon self-stabilized carbon black dispersions such as Cab-O-Jet®300 (Cabot Corporation). Several of these new black, pigment-based inks have provided excellent performance when applied to both text and graphics printing (on plain paper) and photo printing (on glossy photo papers).