NIR Absorbing Inkjet Ink for Colored 3D Sintering
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Solution Overview
Problem
Existing inkjet inks for High Speed Sintering 3D printing using carbon black as an infrared absorbing agent are limited to black or dark-grey colored objects, and non-aqueous inkjet inks face challenges with dispersion stability, viscosity, and health risks from mineral oil hydrocarbons, limiting the production of colored or white objects.
Innovation Solution
A non-aqueous inkjet ink formulation using NIR absorbing nanoscale particles dispersed in solvents free of mineral oil hydrocarbons, with specific solvents and dispersants, achieving stable dispersions and suitable viscosity for reliable jetting, combined with colorants to produce colored or white objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon black is used as an infrared absorbing agent in inkjet ink, then the ink effectively absorbs infrared radiation for sintering, but the resulting 3D printed objects are limited to black or dark-grey colors only
Solution Approach 1:
The patent changes the chemical composition parameter of the infrared absorbing agent from carbon black to alternative materials such as metal oxides (tungsten oxide, molybdenum oxide) or organic dyes that absorb in the infrared region. This parameter change allows the ink to maintain infrared absorption capability while enabling the production of colored or white objects, as these alternative absorbing agents do not impart black coloration to the sintered parts
Solution Approach 2:
The patent employs composite ink formulations that combine infrared absorbing particles with colorants or white pigments. This composite approach allows the infrared absorbing agent to perform its thermal function while the colorant or pigment provides the desired coloration, thereby achieving both effective sintering and color versatility in the final 3D printed objects
2Adaptability or versatility
If inorganic NIR materials are dispersed in non-polar organic solvents, then the ink vehicle is non-aqueous and compatible with certain inkjet heads, but the dispersion stability is poor due to hydrophilic nature of NIR materials
Solution Approach 1:
The patent introduces surface-modified NIR absorbing particles where the particle surfaces are treated with hydrophobic coatings or coupled with hydrophobic dispersants. This intermediary modification creates a bridge between the inherently hydrophilic inorganic NIR materials and the non-polar organic solvent, enabling stable dispersion without aggregation or precipitation
Solution Approach 2:
The patent changes the surface property parameter of the NIR absorbing particles from hydrophilic to hydrophobic through surface modification techniques. This parameter change makes the particles compatible with non-polar organic solvents, ensuring long-term dispersion stability in non-aqueous ink vehicles while maintaining the infrared absorption functionality
3Ease of manufacture
If mineral oil hydrocarbons are used as solvents in non-aqueous inkjet ink, then the ink can be formulated with NIR absorbing particles, but there are health risks and the dispersion stability deteriorates over time
Solution Approach 1:
The patent extracts and removes mineral oil hydrocarbons from the ink formulation, replacing them with safer alternative solvents such as alcohols, esters, ketones, or glycols. This extraction eliminates the health risks associated with mineral oil hydrocarbons while maintaining the ability to formulate stable non-aqueous inks with NIR absorbing particles
Solution Approach 2:
The patent changes the chemical composition parameter of the solvent from mineral oil hydrocarbons to alternative organic solvents with better safety profiles. These alternative solvents maintain the non-aqueous character of the ink (enabling compatibility with certain inkjet heads) while eliminating the harmful effects and improving long-term dispersion stability
4Adaptability or versatility
If the ink contains NIR absorbing particles dispersed in non-aqueous solvent, then the ink can be jetted by inkjet heads designed for non-aqueous inks, but the viscosity and jetting reliability become problematic
Solution Approach 1:
The patent optimizes the viscosity parameter of the non-aqueous ink by adjusting the solvent composition, particle concentration, and additive content. This parameter optimization ensures the ink has appropriate flow characteristics for reliable jetting while maintaining compatibility with non-aqueous inkjet heads and long-term storage stability
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 solution enables the production of colored or white 3D printed objects with improved dispersion stability, reduced health risks, and reliable jetting behavior, overcoming the limitations of mineral oil hydrocarbons and carbon black.
Implementation Method 1
a non-aqueous inkjet ink comprising near infrared (NIR) absorbing particles
Implementation Method 2
irradiating the polymeric powder bed by means of IR radiation such that the NIR absorbing particles are heated and transfer the heat to the polymer particles
Implementation Method 3
a dispersant adsorbed to the surface of the NIR absorbing particles
Implementation Method 4
an NIR/IR lamp irradiates the area in such a way that only those polymer particles which have been covered by the IR/NIR absorbing ink are fused
Implementation Method 5
the NIR absorbing particles are heated and transfer the heat to the polymer particles
Data Source
AI summary
A non-aqueous inkjet ink comprising a near infrared absorbing particle, a dispersant, a solvent, the dispersant is a polymer comprising an amine group or an acidic group and the solvent is selected from the group consisting of ketones, esters, ethers and alcohols. The non-aqueous inkjet ink can act as a fusing agent in a high speed sintering process. The non-aqueous inkjet ink is suitable for printing transparent or coloured 3D-objects.