The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 25, 1987
Filed:
Mar. 28, 1986
Ciba-Geigy Corporation, Ardsley, NY (US);
Abstract
A process for the preparation of formulations of water-soluble organic dyes starting from an aqueous salt-containing suspension of the untreated dye and using membrane separation methods, which process comprises substantially freeing the aqueous suspension of the untreated dye from by-products and reducing the salt concentration by more than half in a first membrane separation treatment, then diluting the dye suspension in a further optional step and effecting deionization and concentration in a second membrane separation treatment and converting the concentrate so obtained into a liquid or solid commercial formulation. This multi-step membrane separation process, e.g. ultrafiltration combined with hyperfiltration, results in a high rate of permeation through the membrane and avoids operating problems caused by membrane clogging.