Organic Black Pigments for Plastics with Low NIR Absorption
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Solution Overview
Problem
Current black pigments, such as carbon black and organic black pigments, face issues with dispersibility, conductivity, and absorption of near-infrared radiation, leading to heating and substrate destruction, while also lacking in jet-black color strength and neutral grey hues when mixed with white pigments.
Innovation Solution
A process involving the reaction of specific compounds in a molar ratio of 1:2 in the presence of a catalyst with a pK≦4.5 in water at 25° C, resulting in highly dispersible, jet-black colorants with improved physical durability and low conductivity, combined with additives like hindered amines and UV absorbers for enhanced weathering stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If carbon black is used as black pigment, then colour strength and blackness are improved, but dispersibility of very fine particles deteriorates and electrical conductivity becomes excessive
Solution Approach 1:
The patent changes the chemical composition parameters by using specific organic compounds (bisbenzofuranone with isatin or indigo) instead of carbon black, achieving jet-black coloration with improved dispersibility in plastics and other substrates while maintaining color strength
Solution Approach 2:
The patent creates composite colorant systems combining organic black colorants with inorganic pigments or other additives to achieve synergistic effects, improving both dispersibility and color performance while reducing the harmful properties of carbon black
2Illumination intensity
If carbon black is used as black pigment, then colour strength is improved, but absorption of near-infrared radiation increases leading to heating and substrate destruction
Solution Approach 1:
The patent changes the optical parameters by selecting organic compounds with specific molecular structures (bisbenzofuranone-isatin-condensed compounds) that have low NIR absorption coefficients while maintaining high visible light absorption, thus preventing heating and substrate damage
Solution Approach 2:
The patent replaces carbon black with organic colorants that can be used at lower concentrations and provide sufficient color strength without the harmful NIR absorption, effectively substituting a harmful material with a safer alternative
3Object-affected harmful factors
If mixed metal oxides are used to reflect NIR radiation, then NIR absorption is reduced, but colour strength deteriorates and heavy metals are introduced
Solution Approach 1:
The patent changes the material parameters by using organic compounds with specific chromophore structures that inherently provide both jet-black coloration and low NIR absorption without requiring heavy metal content, achieving dual performance through molecular design
Solution Approach 2:
The patent extracts and eliminates the heavy metal component from the solution by using purely organic colorants, removing the environmental and health concerns associated with mixed metal oxides while maintaining the desired optical properties
4Ease of operation
If known organic black pigments are used, then dispersibility may be improved, but jet-black color strength deteriorates and neutral grey hues are not achieved
Solution Approach 1:
The patent changes the chemical structure parameters by using specifically condensed bisbenzofuranone-isatin compounds with optimized molecular weights and structures that balance dispersibility in common plastics and solvents with exceptional jet-black color strength and neutral grey mixing 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 process produces black pigments with high color strength, excellent dispersibility, and improved weathering stability in plastics, achieving better physical durability and low NIR absorption compared to existing black pigments.
Implementation Method 1
a compound of the formula (i) is reacted with a compound of the formula (ii) or (iii) in a molar ratio of 1:2 in the presence of a catalyst which in water at 25° C. has a pK≦4.5
Data Source
AI summary
A process for preparing a black colorant, preferably a black pigment, characterized in that a compound of the Formula (I) is reacted with a compound of the Formula (II) in a molar ratio of 1:2, in the presence of a catalyst which in water at 25° C. has a pK≦4.5. For the definition of R1 to R7, refer to the description; preferably all are H. Likewise claimed are new crystal polymorphs obtainable by this process, and preferably single-phase mixed crystals. Also claimed are synergistic compositions. These compositions exhibit increased light stability in plastics stabilized with basic light stabilizers when they are pigmented with colorants of the invention rather than with known black pigments such as carbon black. The specification also relates, furthermore, to the use of the black colorants of the invention for coloring paints, printing inks and plastics in the mass, and to mulch film, instrument panels, woven fabrics, garden furniture items or elements for the construction industry that are pigmented with said colorants.