Method of preparing co-precipitated microcrystalline dye dispersions and layers coated therewith in materials
US6641621B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 4, 2002 |
| Grant date | Nov 4, 2003 |
| Priority date | — |
| Expiry date | Mar 4, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C1/053
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method has been disclosed for preparing a co-precipitated microcrystalline dye dispersion, the absorption spectrum of which exceeds the summoned spectra of individually dispersed dyes, which comprises, as consecutive preparation steps: adding to one vessel, an amount of at least one pentamethine oxonol-type barbituric acid filter dye having ionizable sites in its molecular structure; adding thereto an aqueous alkaline solution in an amount sufficient to completely dissolve the said filter dye while stirring the solution thus formed; adding in another vessel, to an amount of at least one pyrrole type filter dye, an amount of water, followed by adding of an aqueous alkaline solution and a surfactant; followed, after having completely dissolved (under stirring conditions) the said pyrrole type filter dye, by adding to the solution thus formed in the other vessel, the solution formed in the one vessel; adding an aqueous acidic solution up to a pH of less than 3.0; adding an aqueous alkaline solution up to a pH in the range from 4.0 up to 5.5; followed by adding a binder in order to make the dispersion thus obtained ready-for-coating in a filter dye layer on a support, suitable for us…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.