Preparation of permanent color inks from water-soluble colorants using specific phosphonium salts
US6248161A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 11, 1999 |
| Grant date | Jun 19, 2001 |
| Priority date | — |
| Expiry date | Jan 11, 2019 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09D11/328
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Water-fastness in aqueous ink-jet inks containing water-soluble dyes is achieved by using a specific ionic species having a charge opposite to that on the dye molecule. Anionic dyes typically contain sulfonate (or carboxylate) anionic groups. Using at least one specific ionic species of opposite charge, specifically, phosphonium salts, causes the colorant components to "crash" or precipitate out of the water-based ink onto the print medium due to the formation of a suitable charge complex between the ionic parts of the dye and the opposite charge of the counter-ion species. Other positively charged salts, such as quaternary ammonium salts, carbonium salts, iodonium salts, sulfonium salts, and pyrillium salts may be used to improve aqueous dispersion stability and thus printability. Such additional cationic salt partially replaces the phosphonium salt(s). Alternatively, certain surfactants, such as aromatic ethoxylates, polyethylene oxide ethers, or polypropylene oxide ethers may be used to improve print quality.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.