Disperse azo dyes, a process for the preparation thereof and the use thereof
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Solution Overview
Problem
Current azo dyes based on aminophthalimides do not consistently meet modern requirements for light fastness and washing fastness, particularly in dyeing or printing semi-synthetic and synthetic hydrophobic fibre materials like textiles.
Innovation Solution
Development of azo dyes with specific halogen- and cyanosubstituted phthalimides, which exhibit excellent light fastness and washing fastness properties, achieved through a process involving a mixture of alkali metal cyanide and heavy metal cyanide in aprotic polar solvents, resulting in dyes with improved fibre-levelness and surface-levelness on textiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If currently known azo dyes based on aminophthalimides are used, then the dyeing process can be performed, but the light fastness and washing fastness of the dyeings do not satisfy modern requirements
Solution Approach 1:
The patent changes the chemical parameters of the phthalimide component by introducing specific halogen (Cl, Br) and cyano groups at defined positions (R2-R8). This structural modification transforms the dye molecules to achieve both good light fastness and excellent washing fastness, resolving the contradiction between reliability and manufacturing precision of fastness properties
Solution Approach 2:
The invention creates composite dye structures by combining halogen-substituted phthalimide moieties with cyano substituents and aromatic coupling components. This composite molecular structure achieves synergistic effects that simultaneously improve light fastness and washing fastness, overcoming the limitations of conventional aminophthalimide dyes
2Reliability
If new azo dyes with specific halogen- and cyanosubstituted phthalimides are developed, then light fastness and washing fastness are significantly improved, but the dyeing cost and synthesis complexity increase
Solution Approach 1:
The patent employs preliminary action by using readily available halogen-substituted phthalimide starting materials that have been pre-synthesized with the necessary halogen and cyano groups. This allows the final azo dye synthesis to proceed directly without requiring complex multi-step functionalization, thus improving washing fastness while limiting synthesis complexity
Solution Approach 2:
The halogen-substituted phthalimide acts as an intermediary structure that facilitates the introduction of cyano groups through controlled substitution reactions. This intermediary approach enables systematic molecular design to achieve superior fastness properties while maintaining manageable synthesis complexity through modular construction
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The new azo dyes demonstrate very good light fastness and washing fastness, providing high-quality dyeings with excellent in-use fastness properties, including resistance to light, heat, chlorine, and perspiration, and are suitable for various textile materials, including polyester.
Implementation Method 1
The halogen/cyano exchange of dibromo compounds which leads to the claimed dyes of formula (1) is likewise known per se, for instance from WO 2002/068539.
Data Source
AI summary
The present invention relates to azo dyes of formula (1), wherein R1 denotes C1-C12alkyl which is unsubstituted or substituted by one or more C1-C12alkoxy groups, hydroxyl groups, amino groups, cyano groups or halogen atoms and which may be interrupted one or more times by the radical -O-, -S-, -NR4-, -COO- or –OOC-; R4 is hydrogen or C1-C12alkyl; either R2 is cyano and R3 is halogen or R2 is halogen and R3 is cyano; and Ar represents a carbocyclic or heterocyclic aromatic radical, to the process for the preparation thereof, to mixtures containing said dyes and to the use thereof in dyeing or printing semi-synthetic and especially synthetic hydrophobic fibre materials, more especially textile materials.