Aqueous Ink Composition Using Sulfonated Polyester and Isoprene Rubber
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Solution Overview
Problem
Current digital offset printing inks face challenges in achieving high viscosity latitude for effective ink transfer at varying temperatures, often requiring curable monomers that can lead to migration issues, especially in applications like food packaging, and struggle with wetting and transfer properties on different substrates.
Innovation Solution
An aqueous ink composition comprising water, an optional co-solvent, an optional colorant, a sulfonated polyester with a degree of sulfonation of at least 7.5 mol percent, and an isoprene rubber, which maintains a specific viscosity range at different temperatures, ensuring efficient ink transfer and cohesion without curable monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If curable monomers are used to achieve high viscosity latitude, then ink transfer effectiveness is improved, but migration issues occur especially in food packaging applications
Solution Approach 1:
The patent removes curable monomers from the ink formulation entirely, extracting the harmful component while maintaining ink transfer effectiveness through alternative thickening agents (sulfonated polyester and isoprene rubber) that do not migrate
Solution Approach 2:
The patent uses a composite system combining sulfonated polyester and isoprene rubber as thickening agents to replace curable monomers, achieving the desired viscosity latitude and ink transfer properties without the harmful migration effects
2Productivity
If viscosity is increased for effective ink transfer, then transfer properties are improved, but ink take up and delivery becomes difficult
Solution Approach 1:
The patent creates a dynamic viscosity system where the ink exhibits different viscosity characteristics at different temperatures: high viscosity at room temperature for effective transfer, and lower viscosity at elevated temperatures for easy delivery and application
Solution Approach 2:
The patent utilizes temperature as a parameter to control viscosity, allowing the ink to be delivered at high temperature (lower viscosity) and transfer at lower temperature (higher viscosity), thereby resolving the contradiction between ease of delivery and transfer efficiency
3Object-affected harmful factors
If aqueous-based ink is used for safety, then compatibility with food packaging is improved, but wetting and transfer properties on different substrates deteriorate
Solution Approach 1:
The patent modifies the chemical parameters of the aqueous ink by incorporating sulfonated polyester with high degree of sulfonation (at least 7.5 mol percent) to enhance wetting properties while maintaining the safety of aqueous-based formulation
Solution Approach 2:
The patent creates a composite aqueous system combining sulfonated polyester and isoprene rubber that work synergistically to improve wetting and transfer properties on various substrates while maintaining food packaging safety
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 composition achieves 100% transfer on digital offset printing fixtures without partial drying, demonstrating improved wetting, release properties, and compatibility with non-aqueous fountain fluids, suitable for food-grade and medical-grade printing.
Implementation Method 1
The ink composition has a first viscosity of from about 3,000 to about 90,000 millipascal seconds at an ink take up temperature of from 45 °C to 80 °C; and a second viscosity of from 100,000 to 2,000,000 millipascal seconds at an ink transfer temperature of from 18 °C to 30 °C
Data Source
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AI summary
An aqueous ink composition including water; an optional co-solvent; an optional colorant; a sulfonated polyester; and an isoprene rubber. A process of digital offset printing, the process including applying an ink composition onto a re-imageable imaging member surface at an ink take up temperature, the re-imageable imaging member having dampening fluid disposed thereon; forming an ink image; transferring the ink image from the re-imageable surface of the imaging member to a printable substrate at an ink transfer temperature; wherein the ink composition comprises: water; an optional co-solvent; an optional colorant; a sulfonated polyester; and an isoprene rubber. A process including combining a sulfonated polyester resin, water, an optional co-solvent, an optional colorant, a sulfonated polyester, and an isoprene rubber to form an aqueous ink composition.