Diarylide Yellow Pigment Shade and Purity via Segmented Coupling
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Solution Overview
Problem
Diarylide yellow pigments, particularly those like C.I. Pigment Yellow 83, face issues with aromatic amine impurities that cause health concerns and regulatory compliance problems, and existing methods for reducing these impurities often decrease product yield and result in pigments with different shades and stability issues.
Innovation Solution
A diarylide yellow pigment is formed by a coupling reaction of tetrazotized 3,3'-dichlorobenzidine with a mixture comprising 25-90% 4-chloro-2,5-dimethoxy-acetoacetanilide and 75-10% 2,4-dimethyl-acetoacetanilide, creating a solid solution with a redder shade and improved durability similar to C.I. Pigment Yellow 83 while minimizing aromatic amine impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If C.I. Pigment Yellow 83 is produced using AADMCA as the coupling agent, then the pigment achieves a desirable reddish shade and good fastness properties, but aromatic amine impurities are generated causing health concerns and regulatory compliance issues
Solution Approach 1:
The patent divides the single coupling agent approach into a segmented system using two different coupling agents (AAMX and AADMCA) in specific ratios. This segmentation allows the reaction mixture to produce multiple pigment variants where the majority component (AAMX) suppresses aromatic amine formation while the minority component (AADMCA) maintains the desired reddish shade and fastness properties.
Solution Approach 2:
The patent changes the compositional parameters by using a mixture of coupling agents in controlled ratios (5-95% AAMX and 95-5% AADMCA) rather than using a single coupling agent. This parameter change enables optimization of both harmful impurity levels and desirable pigment properties simultaneously.
2Object-generated harmful factors
If extensive purification is applied to reduce aromatic amine levels in C.I. Pigment Yellow 83, then the harmful impurity level decreases, but product yield decreases and the process becomes more complex
Solution Approach 1:
The patent applies preliminary action by preventing aromatic amine impurity formation at the source through the use of AAMX as the primary coupling agent, rather than allowing impurities to form and then requiring extensive purification. This preventive approach maintains high product yield while achieving low impurity levels.
Solution Approach 2:
The patent converts the potential harm of using AADMCA (which generates aromatic amine impurities) into a benefit by using it in controlled minor amounts to enhance shade and fastness properties, while the majority AAMX component suppresses impurity formation. This transforms what would be a harmful process into a beneficial one.
3Object-generated harmful factors
If AAMX is used as the coupling agent to form C.I. Pigment Yellow 13, then aromatic amine impurities are minimized, but the pigment exhibits a greener shade rather than the desired reddish shade
Solution Approach 1:
The patent merges two different coupling agents (AAMX and AADMCA) in a synergistic combination where AAMX provides low aromatic amine formation and AADMCA provides the desired reddish shade. The specific ratio range (5-95% AAMX and 95-5% AADMCA) optimizes the merged properties to achieve both low impurities and desirable shade characteristics.
Solution Approach 2:
The patent creates a composite pigment system by combining products from two different coupling reactions. The resulting pigment is a composite material with properties that reflect contributions from both AAMX-based and AADMCA-based pigment molecules, achieving a balance between low impurity content and desirable shade and fastness properties.
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 resulting pigment exhibits a redder shade with reduced aromatic amine content, maintaining the morphology and fastness properties of C.I. Pigment Yellow 83, and can be used in various applications such as printing inks, plastics, and coatings with enhanced stability and compliance.
Implementation Method 1
A diarylide yellow pigment formed by a coupling reaction of tetrazotized 3,3'-dichlorobenzidine and a mixture comprising 25-90 % by weight of 4-chloro-2,5-dimethoxy-acetoacetanilide and 75-10 % by weight of 2,4-dimethyl-acetoacetanilide
Data Source
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AI summary
A diarylide yellow pigment formed by a coupling reaction of a benzidine and a mixture comprising 4-chloro-2,5-dimethoxy-acetoacetanilide and 2,4-dimethyl-acetoacetanilide. The diarylide yellow pigment has a desirable reddish shade than C.I. Pigment Yellow 83, exists in a solid solution, and contains fewer aromatic amine impurities.