Humectant Blend Ink for Digital Offset Printing
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Solution Overview
Problem
Current digital offset printing inks face challenges with viscosity and cohesion issues, leading to poor transfer properties and contamination, and there is a need for non-UV curable, food-grade inks with expanded temperature stability and compatibility with re-imageable surfaces and fountain solutions.
Innovation Solution
A humectant blend comprising a first humectant with a freezing point and a second humectant that suppresses this point, combined with a sulfonated polyester and optional co-solvent and colorant, to create an ink composition suitable for digital offset printing, ensuring stable viscosity and cohesion across various temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single humectant is used in the ink composition, then the formulation is simpler, but the ink solidifies at storage temperatures below its freezing point
Solution Approach 1:
The patent uses a composite humectant system comprising multiple humectants (e.g., glycerol, ethylene glycol, propylene glycol) in specific combinations. This composite approach allows the ink to maintain liquid state at storage temperatures while preserving all necessary humectant functions, resolving the contradiction between formulation simplicity and storage stability.
Solution Approach 2:
The patent modifies the physical parameters of the humectant system by selecting humectants with appropriately low freezing points and combining them in specific ratios. This parameter optimization enables the ink to remain fluid at refrigeration temperatures (e.g., 4°C) without requiring complex additives or processing steps.
2Speed
If UV curable components are used in the ink, then drying speed improves, but food-grade safety and compatibility with digital offset printing are compromised
Solution Approach 1:
The patent removes UV curable components from the ink formulation entirely, extracting the harmful element while retaining the essential function of rapid drying through alternative water-based evaporation and oxidation mechanisms suitable for food-grade applications.
Solution Approach 2:
The patent employs water-based volatile carriers that evaporate quickly without requiring UV curing. This approach uses simple, food-safe, biodegradable components that provide sufficient drying speed for digital offset printing without the complexity and safety concerns of UV curable systems.
3Ease of operation
If ink viscosity is reduced to improve transfer properties, then ink flow improves, but ink cohesion and tack stability deteriorate
Solution Approach 1:
The patent optimizes the viscosity parameter by carefully selecting and ratioing humectants with different molecular weights and viscosities. This creates an ink composition with intermediate viscosity that simultaneously achieves good flow characteristics for transfer and sufficient cohesion for tack stability in digital offset printing systems.
Solution Approach 2:
The patent uses a composite of multiple humectants and water-soluble polymers that work synergistically to provide both fluidity and cohesion. The combination of small molecules (glycerol, glycols) with larger polymer structures creates an ink that flows well during transfer but maintains structural integrity and tack 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 ink composition achieves 100% transfer efficiency and robust storage stability, maintaining desired properties for food-grade applications, with improved wetting and release characteristics, and compatibility with digital offset printing systems.
Implementation Method 1
the second humectant suppresses the freezing point of the first humectant such as to impart to the ink composition the characteristic of being able to be stored at a desired temperature without solidifying
Data Source
AI summary
An ink composition including a humectant blend comprising a first humectant and a second humectant; wherein the first humectant has a freezing point; wherein the second humectant suppresses the freezing point of the first humectant such as to impart to the ink composition the characteristic of being able to be stored at a desired temperature without solidifying; water; an optional co-solvent; an optional colorant; and a sulfonated polyester. A process of digital offset printing using the ink composition.