Dithiolene Metal Complexes for Infrared Absorption
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Solution Overview
Problem
Current colorless IR absorbers for security printing and optical filter applications face challenges in achieving high light and thermal stability while maintaining minimal visible absorption and resistance to chemicals and solvents.
Innovation Solution
Development of dithiolene metal complexes with specific particle sizes and compositions, such as those of formula (I), which are kneaded with inorganic salts to enhance their absorbing properties, thermal and light fastness, and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional IR absorbers are used for security printing, then infrared absorption is achieved, but visible absorption increases causing noticeable coloration
Solution Approach 1:
The patent changes the chemical composition parameters by using specific transition metal complexes (Cu, Ni, Co, Zn) with particular ligands (dithiolenes, phenanthroline, bipyridine) to achieve selective infrared absorption. The molecular structure parameters are optimized to create absorption bands in the infrared region while maintaining transparency in the visible region, resolving the contradiction between infrared absorption and visible coloration.
Solution Approach 2:
The invention employs composite material structures by combining transition metal centers with organic ligands to form complex coordination compounds. These composite molecular structures exhibit selective optical properties where the metal-ligand combination creates infrared absorption while the organic components maintain visible transparency, solving the contradiction between the two absorption regions.
2Use of energy by moving object
If IR absorbers with high infrared absorption are developed, then optical filter performance improves, but chemical stability and resistance to chemicals deteriorate
Solution Approach 1:
The patent optimizes chemical stability parameters by selecting specific transition metals (Cu, Ni, Co, Zn) and their oxidation states, combined with stable ligand structures (dithiolenes, phenanthroline, bipyridine). This parameter optimization creates complexes with high infrared absorption that simultaneously possess enhanced chemical stability and resistance to chemicals and solvents.
Solution Approach 2:
The invention uses composite coordination chemistry where transition metal centers are bonded to stable organic ligands, creating hybrid structures that combine the optical properties of the metal complexes with the chemical stability of the organic components. This composite approach resolves the contradiction between infrared absorption capability and chemical resistance.
3Stability of the object's composition
If dithiolene metal complexes are kneaded with inorganic salts, then thermal and light fastness improve, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-kneading the dithiolene metal complexes with inorganic salts before final product formation. This preliminary mixing step ensures uniform distribution and proper interaction between the complex and salt components, achieving enhanced thermal and light fastness while simplifying subsequent processing steps.
Solution Approach 2:
The invention optimizes manufacturing parameters by controlling the kneading conditions (temperature, time, mixing intensity) to achieve the desired particle size distribution and composition uniformity. By optimizing these parameters, the process achieves improved thermal and light fastness without excessive manufacturing complexity.
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 particles exhibit improved absorbing properties, high thermal and light fastness, and resistance to chemicals and solvents, making them suitable for security printing and optical filter applications with minimal visible absorption.
Implementation Method 1
the particles of a compound of formula (I)... their use as almost colourless IR absorbers
Implementation Method 2
whose infrared absorption is a consequence of electronic transitions within the d-shell of the transition element
Implementation Method 3
kneaded with inorganic salts to enhance their absorbing properties, thermal and light fastness
Data Source
AI summary
The present invention relates to particles of a compound of formula M (I), wherein M is selected from Ni, Pd and Pt, X1 and X2 are each independently of each other sulfur or oxygen, R1, R2, R3, and R4 are independently selected from an unsubstituted, or substituted al- kyl group, an unsubstituted, or substituted cycloalkyl group, an unsubstituted or substi- tuted aryl group and an unsubstituted or substituted heteroaryl group, wherein the particles have a median particle size (D50) in the range of from 30 nm to 90 nm, preferably from 40 nm to 80 nm, more preferably 50 to 70 nm with D10 being greater than 20 nm, especially greater than 25 nm, very especially greater than 30 nm, their use as almost colourless IR absorbers, for optical filter applications, especially for plasma display panels, or for laser welding of plastics. The compounds may be used in compositions for inks, paints and plastics, especially in a wide variety of printing systems and are particularly well-suited for security applications.