Pigment Composition Color Strength and Transparency
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Solution Overview
Problem
C.I. Pigment Yellow 191 has lower color strength and transparency compared to other pigments like P.Y.180, limiting its applications in coloring materials.
Innovation Solution
A pigment composition is developed by combining C.I. Pigment Yellow 191 with specific yellow pyrazolone pigments as doping components, enhancing color strength and transparency through azo coupling and lacquering processes, using diazotization and coupling reactions with alkaline metal nitrites and strong mineral acids, followed by heat treatment and grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If C.I. Pigment Yellow 191 is used for coloring plastics, then high light fastness and heat resistance are achieved, but color strength is significantly lower compared to other pigments
Solution Approach 1:
The patent creates a composite pigment system by combining C.I. Pigment Yellow 191 with specific yellow pyrazolone pigments (such as C.I. Pigment Yellow 183 or compounds of formula (2)). This composite approach allows the mixture to achieve enhanced color strength while maintaining the favorable light fastness and heat resistance properties of the base P.Y. 191 pigment, as the dopant pigments are selected to be compatible with P.Y. 191's performance characteristics.
2Reliability
If C.I. Pigment Yellow 191 is used for coloring materials, then good fastness is achieved, but transparency is reduced
Solution Approach 1:
The patent modifies the optical parameters of the pigment composition by introducing yellow pyrazolone pigments that have different transparency characteristics compared to pure P.Y. 191. The dopant pigments are selected and dosed (0.05 to 5 mol%) to optimize the balance between fastness and transparency, effectively changing the optical parameters of the overall composition without compromising the 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 composition exhibits high color strength, good fastness, and high transparency, making it suitable for various applications in materials like plastics, paints, and printing inks.
Implementation Method 1
The coupling is possible using the direct or indirect method, but is preferably carried out directly, i.e. the diazonium salt is added to the coupling component. The coupling reaction can be carried out in a temperature range between -5 °C and 80 °C
Implementation Method 2
Alkaline metal nitrites or the alkyl nitrites of short-chain alkanes, together with strong mineral acids, are suitable for the diazotization reaction. The reaction can be carried out in a temperature range of -5 °C to +35 °C, preferably between 0 °C and 10 °C.
Implementation Method 3
After lacquering, the pigment composition according to the invention can be subjected to a heat treatment in an aqueous, aqueous-organic or organic medium at temperatures between 60 °C and 98 °C, preferably between 60 °C and 85 °C, if necessary under pressure, for 0.1 to 4 hours
Data Source
AI summary
The invention relates to a pigment composition based on P.Y. 191 of the formula (1) containing 0.05 to 30 mol%, based on the sum of P.Y. 191 and a further yellow colorant, of at least one further yellow colorant of the formula (2) and/or of C.I. Pigment Yellow 100 in which R1, R2, R3 and R4 are each independently hydrogen, halogen, -CH3, -NO2, or NH-R6 where R6 is C1-C4-alkyl; R5 is methyl or carboxyl, and where the compound of the formula (2) is not C.I. Pigment Yellow 191.