Methine Dye Composition for Polyamide Thermal and Light Fastness
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Solution Overview
Problem
Current yellow dyes for plastics, particularly polyamides, lack sufficient fastness properties, including thermal stability and light resistance, which are essential for bulk colouration, especially when combined with glass fibers.
Innovation Solution
Development of novel methine dyes with specific structural formulas that provide improved light fastness, thermal stability, and colour strength, allowing for yellow to orange colouration of plastics, especially polyamides, through the use of dyes with specific alkyl, halogen, and phenyl substituents, which can be incorporated into molten plastics or monomers during polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If pigments are used for bulk colouration of polyamide, then thermal stability is improved, but light resistance and transparency deteriorate
Solution Approach 1:
The invention changes the chemical structure parameters of the dye molecule by introducing specific substituents (cyano group at position 3, various alkyl groups at positions 5 and 6, and aromatic substituents at positions 7 and 8) to achieve both thermal stability and light resistance simultaneously, resolving the contradiction between these two properties
Solution Approach 2:
The invention creates a composite molecular structure combining the methine chromophore with barbituric acid derivative and specific substituent groups, forming a complex dye molecule that integrates multiple functional characteristics including thermal stability, light resistance, and transparency
2Object-affected harmful factors
If known solvent yellow dyes are used, then transparency is improved, but thermal stability deteriorates
Solution Approach 1:
The invention modifies the molecular parameters by introducing stable aromatic substituents (phenyl, naphthyl groups) and electron-withdrawing cyano groups that increase thermal stability while maintaining the transparency characteristics of solvent dyes
3Ease of manufacture
If yellow dyes are used for polyamide colouration, then ease of manufacture is improved, but fastness properties deteriorate
Solution Approach 1:
The invention optimizes the molecular parameters by selecting specific substituent combinations that enhance fastness properties (light fastness, thermal fastness) while maintaining the synthetic accessibility and manufacturing simplicity of conventional dyes
Data Source
AI summary
The present invention relates to novel methine dyes, methods for the preparation thereof and use thereof for dyeing plastics, especially polyamides, so as to obtain yellow to orange colourings with improved light fastness and improved thermal stability. Methine dyes for example accord to the formula (I)in whichR1 is hydrogen, halogen, alkyl, COOH or COOR9,R2 is oxygen or sulfur,R3 is hydrogen, halogen, COOH, COOR10 or CN,R4 is alkyl or phenyl,R5 and R6 are each independently alkyl,R7 and R8 are each independently hydrogen, halogen, alkyl or COOR11, andR9, R10 and R11 are each independently alkyl.