Process for the preparation of low-salt, liquid dyestuff preparations

US6120561A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Peter Wild · Odenthal, DE
• Volker Paulat · Monheim, DE
• Wolfgang Frank
• Shaun Murphree

Key dates

• Filing date: Apr 17, 1997
• Grant date: Sep 19, 2000
• Expiry date: Apr 17, 2017

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S8/919
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

Process for the preparation of low-salt liquid dyestuff preparations, characterized in that they are obtained by: PA1 a) diazotization of an aromatic amine, PA1 b) 2-fold coupling of the diazo component obtained according to a) to I-acid-urea, in the presence of an inorganic base and in the absence of an organic base, PA1 c) desalination and, if appropriate, concentration by means of a pressure permeation of the reaction mixture obtained according to b), so that an inorganic salt content of less than 1% by weight is achieved.