Continuous Inkjet Ink Composition for Fast Drying and Safe Solvents
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Solution Overview
Problem
Existing continuous inkjet inks face challenges in meeting safety and regulatory requirements due to the use of highly regulated solvents like methanol and MEK, leading to health and environmental concerns, and they often fail to provide adequate adhesion and stability on non-porous substrates.
Innovation Solution
Ink compositions utilizing volatile Cs ketone solvents such as 2-pentanone, 3-methyl-2-butanone, and binder resins like polyvinyl butyral, with minimal or no MEK, methanol, and ethanol, ensuring compliance with safety regulations and enhancing adhesion and drying times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If methanol and MEK are used as solvents in continuous inkjet ink, then fast drying time and good adhesion are achieved, but health and safety concerns arise due to regulation under VOC and HAP lists
Solution Approach 1:
The patent changes the chemical composition parameters by replacing regulated solvents (methanol, MEK) with alternative solvents (acetone, ethyl acetate, dioxolane) that have different regulatory statuses. This parameter change maintains the fast drying performance while improving regulatory compliance, as the alternative solvents are not on the Japan ISHL Class 2 Organic Solvent List or VOC/HAP regulations.
Solution Approach 2:
The patent employs acetone as a solvent that is highly volatile and evaporates quickly, providing fast drying without requiring complex exhaust systems. Acetone's short residence time in the formulation and rapid evaporation make it an effective replacement that eliminates the need for expensive exhaust treatment infrastructure while maintaining drying performance.
2Object-affected harmful factors
If acetone and methyl acetate are used as alternative solvents to avoid regulated solvents, then health and safety concerns are reduced, but volatility increases leading to higher makeup consumption and reduced printer reliability in hot environments
Solution Approach 1:
The patent creates a composite solvent system combining acetone with other solvents (ethyl acetate, dioxolane) and additives (conductive agents, binder resins) to achieve a balanced formulation. This composite approach leverages acetone's fast drying capability while the other components moderate its excessive volatility, providing both regulatory compliance and environmental stability in hot operating conditions.
Solution Approach 2:
The patent adjusts the concentration parameters of acetone and other solvents in the ink formulation to optimize the balance between drying speed and volatility control. By carefully controlling the acetone content and combining it with less volatile solvents, the formulation maintains fast drying while reducing makeup consumption and improving reliability in hot environments.
3Object-affected harmful factors
If dioxolane and ethyl acetate are used as solvents, then health and safety concerns are reduced, but ink conductivity decreases requiring more conductive agent which leads to poorer adhesion
Solution Approach 1:
The patent develops a composite formulation combining dioxolane or ethyl acetate with specific binder resins (polyvinyl butyral, cellulose acetate propionate) and conductive agents (metal oxides, carbon blacks) to achieve optimal adhesion. The binder resin system compensates for the reduced conductivity by providing strong substrate bonding, while the conductive agents restore electrical conductivity without compromising adhesion performance.
Solution Approach 2:
The patent optimizes the concentration parameters of conductive agents and binder resins to compensate for the lower conductivity of dioxolane/ethyl acetate-based solvents. By adjusting these parameters, the formulation achieves both adequate conductivity and strong adhesion, resolving the trade-off between solvent choice and performance.
4Object-affected harmful factors
If 1,2-dimethoxyethane is used as a solvent alternative, then it is not on the Japan ISHL Class 2 Organic Solvent List, but it poses more health hazards than MEK and other regulated solvents
Solution Approach 1:
The patent converts the regulatory advantage of 1,2-dimethoxyethane (not being on the Japan ISHL Class 2 list) into a potential benefit while mitigating its health hazards through proper formulation and ventilation design. The solvent is used in controlled concentrations and combinations where its regulatory status provides an advantage, while its health hazards are managed through engineering controls and safe working practices.
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 ink compositions achieve fast drying times and superior adhesion on various substrates, including non-porous materials, while being safe for workers and compliant with international health and safety standards, without the need for expensive exhaust systems.
Implementation Method 1
These inks produce a fast dry time due to their volatility
Implementation Method 2
good adhesion... superior adhesion on various substrates, including non-porous materials
Data Source
AI summary
Embodiments of the invention relate to ink compositions suitable for applications in the printing industry, for example continuous inkjet printing, including ultra-high speed continuous inkjet printing. The ink compositions use volatile C5 ketone (pentanone) solvents (e.g., 2-pentanone, 3-pentanone, or 3-methyl-2-butanone) as a major solvent or the only solvent, and also include a binder resin and a colorant, but preferably contain substantially no acetone, methanol, or methyl ethyl ketone, or other solvents listed on the Japan ISHL class II organic solvents list. Preferred ink compositions can contain up to 30% ethanol, n-propanol, or other solvents not listed on the Japan ISHL class II organic solvents list, but preferably contain substantially no ethanol.