Conductive Ink Jet Printing Composition for Stable Pattern Formation
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Solution Overview
Problem
Conductive ink compositions used in ink jet printing tend to segregate over time, require re-dispersion, and can lead to nozzle clogging, while also posing environmental and health concerns due to nanoparticle use, and often have complex formulations that reduce versatility.
Innovation Solution
A conductive ink jet printing ink composition comprising 60-84.5 wt.% organic solvent, 0.5-5 wt.% ethyl cellulose binder, and 15-25 wt.% silver particles with a d50 value of 130-800 nm, optionally with antioxidizing agents and a dispersing agent, formulated to prevent segregation and clogging, and suitable for various substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive ink compositions are formulated with metal particles and binders, then electrical conductivity is achieved, but the composition tends to segregate over time
Solution Approach 1:
The patent uses a specifically formulated binder system comprising ethyl cellulose and cellulose acetate butyrate as intermediary substances that mediate between the conductive metal particles and the solvent. This binder combination prevents segregation by providing optimal adhesion and suspension properties, maintaining both conductivity and long-term stability without requiring photographic masks or complex curing processes.
2Stability of the object's composition
If dispersing agents are added to prevent segregation, then composition stability is improved, but electrical conductivity is reduced
Solution Approach 1:
The patent optimizes the binder composition parameters by selecting specific cellulose derivatives (ethyl cellulose and cellulose acetate butyrate) with controlled molecular weights and ratios. This parameter optimization provides sufficient dispersion stability through the binder's inherent properties rather than adding separate dispersing agents, thereby maintaining electrical conductivity while preventing segregation.
3Reliability
If complex formulations with multiple components are used, then printing performance is improved, but versatility and ease of manufacture are reduced
Solution Approach 1:
The patent creates a universal conductive ink formulation where the binder system (ethyl cellulose and cellulose acetate butyrate) performs multiple functions simultaneously: it provides suspension stability, adhesion to substrate, controlled drying, and maintains conductivity. This multi-functional approach eliminates the need for separate dispersing agents, thickening agents, or complex curing systems, thereby improving ease of manufacture while maintaining printing performance.
4Stability of the object's composition
If nanoparticle sizes are used to improve stability, then composition stability is improved, but environmental and health concerns increase
Solution Approach 1:
The patent changes the particle size parameter from nanoscale to microscale (0.1-10 μm average diameter), which maintains solution stability through the optimized binder system while eliminating the environmental and health concerns associated with nanoparticles. The larger particles are less hazardous yet achieve comparable or superior stability through the cellulose-based binder formulation.
Data Source
AI summary
A conductive ink jet printing ink composition is provided comprising the following components: (a) 60 – 84.5 wt.-% of an organic solvent or a mixture of organic solvents, (b) 0.5 – 5 wt.-% of a binder, wherein the binder comprises ethyl cellulose in an amount of a range of 85 to 100 wt.-%, based on the total amount of the binder, (c) 15 – 25 wt.-% of silver particles having a d50-value in a range of 130 nm to 800 nm, (d) optionally antioxidizing agents, (e) optionally a dispersing agent for the silver particles different from binder (b), wherein all amounts are referred to the total amount of the ink jet printing ink composition, if not defined otherwise.