Reduced Indium Tin Oxide Laser Marking Ink
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Solution Overview
Problem
Existing laser marking technologies using NIR radiation and metal salts struggle to produce effective contrasting images, particularly at lower fluence levels, due to limitations in absorption properties and stability of materials like copper hydroxy phosphate (CHP) compared to non-stoichiometric compounds.
Innovation Solution
Incorporating reduced non-stoichiometric indium tin oxide (r-ITO) as a NIR absorber in ink formulations with oxymetal anions, which enhances absorption properties and stability, allowing for distinct image formation under near-infrared laser radiation, particularly at wavelengths where CHP fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If copper hydroxy phosphate (CHP) is used as a NIR-absorbing metal salt for laser marking, then colour change reaction can be initiated with NIR laser radiation, but the absorption properties and image contrast are insufficient particularly at lower fluence levels
Solution Approach 1:
The patent changes the chemical composition parameters of the metal salt from conventional options like copper hydroxy phosphate to specifically selected metal salts with optimal NIR absorption characteristics. This parameter change enables superior absorption properties that produce strong image contrast even at lower fluence levels, directly resolving the contradiction between image quality and energy consumption.
2Reliability
If conventional metal salts are used for NIR laser marking, then marking can be achieved, but the stability and absorption properties are limited compared to non-stoichiometric compounds
Solution Approach 1:
The patent employs composite material strategies by combining specific metal salts with oxymetal anion components in carefully formulated compositions. This composite approach creates a material system with enhanced stability and absorption properties that exceed those of conventional single-component metal salts, while the complexity is justified by the significant performance improvements in reliability.
3Illumination intensity
If r-ITO is used as a NIR absorber in ink formulations, then absorption properties and image formation are significantly improved, but the material is non-stoichiometric requiring precise control
Solution Approach 1:
The patent deliberately changes from stoichiometric to non-stoichiometric material composition, specifically using r-ITO with controlled oxygen deficiency. This parameter change in the material composition enables superior NIR absorption efficiency and image formation. The manufacturing precision challenge is addressed through controlled synthesis methods that consistently produce the desired non-stoichiometric phase with the specific properties needed for optimal laser marking performance.
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
r-ITO demonstrates stronger image formation and higher efficacy compared to CHP at lower fluence levels, with improved thermal and light stability, and compatibility with various substrates and binders, enabling effective laser marking across different wavelengths.
Implementation Method 1
reduced a non-stoichiometric compound such as r-ITO, e.g. in the form of a nanopowder, can function as a highly effective absorber of near infra-red radiation in the region 900 to 2500 nm
Implementation Method 2
NIR laser radiation (i.e. at 800 to 2000 nm) to initiate a colour change reaction when a NIR-absorbing metal salt is used in combination with a substance that normally undergoes a colour change reaction at much longer wavelength
Data Source
AI summary
An ink formulation comprises a marking component, e.g. ammonium octamolybdate, and a metal salt that absorbs laser irradiation at 780-2500 nm, e.g. reduced indium tin oxide, and thereby causes the marking component to change colour.