Low Odor Radiation Curable Ink for Corrugated Packaging
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Solution Overview
Problem
Existing inkjet inks for drop-on-demand printing face challenges in achieving low odor, high flexibility, and fast curing while maintaining viscosity suitable for jetting, particularly for packaging applications like corrugated cardboard, where higher cross-linking leads to brittleness and odor issues from monofunctional monomers.
Innovation Solution
A low odor radiation curable ink composition comprising 10-40% 4-hydroxybutylacrylate, 5-25% urethane (meth)acrylate oligomer, 10-55% diacrylates, photoinitiators, additives, and pigments, with minimal monofunctional monomers that have undesired odors, ensuring a viscosity of 8-14 cP for jetting and flexibility, using LED-generated light for curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If monomers with multiple acrylate groups are used to increase cross-linking, then odor is reduced and curing speed increases, but the ink becomes more brittle and unsuitable for bending applications
Solution Approach 1:
The patent changes the chemical parameters of the monomers by selecting specific monofunctional monomers with particular molecular structures (longer alkyl chains, cyclic structures) that have lower vapor pressures and reduced odors. This allows achieving low odor without increasing cross-linking density, thereby maintaining flexibility.
Solution Approach 2:
The patent creates a composite ink formulation by combining multiple monofunctional monomers with different chemical structures (cyclic, aliphatic, aromatic) and specific functional groups. This composite approach achieves synergistic effects where the combination provides both low odor and maintained flexibility that individual monomers cannot achieve alone.
2Productivity
If monomers with multiple acrylate groups are used to increase cross-linking, then curing speed increases, but the ink becomes more brittle and unsuitable for bending applications
Solution Approach 1:
The patent optimizes the molecular weight and structural parameters of monofunctional monomers to achieve faster curing rates without increasing functionality. The selected monomers have specific structural features that enhance polymerization kinetics while maintaining linear chain structures that provide flexibility.
Solution Approach 2:
The patent uses monofunctional monomers as molecular templates or building blocks that replicate flexible chain structures throughout the polymer network. These monomers serve as flexible spacers that copy the desired flexibility property throughout the cured ink matrix, allowing fast curing without brittleness.
3Ease of operation
If low molecular weight monomers are used to achieve low viscosity for jetting, then jetting performance improves, but vapor pressure increases leading to stronger odors
Solution Approach 1:
The patent carefully selects monomers with specific molecular weight ranges (balancing low enough for jetting but high enough to reduce vapor pressure) and optimizes their structural parameters. The selected monomers have molecular weights and vapor pressures within specific ranges that simultaneously satisfy jetting requirements and odor reduction goals.
Solution Approach 2:
The patent introduces local structural features (cyclic groups, aromatic rings, specific functional groups) within the monomer molecules that locally increase intermolecular forces and reduce vapor pressure, while maintaining overall low molecular weight for jetting performance. This local quality enhancement reduces odor without sacrificing jetting capability.
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 provides a fast curing, flexible, and low odor solution suitable for single pass printing on paper-based corrugated materials, minimizing odor both in the wet and cured states, and ensuring acceptable flexibility without brittleness, making it suitable for tertiary packaging applications.
Implementation Method 1
The ink is curable by actinic radiation, more specifically using LED generated light
Data Source
AI summary
The present invention relates to low odor radiation curable ink compositions. The composition comprises 10-40% w/w of 4-hydrobutylacrylate, 5-25% of a urethane (math)acrylate oligomer, 10-55% of diacrylates, one or more photoinitiators, one or more additives, and one or more pigments. The composition excludes many monofunctional monomers that have distinct odor and are commonly used in an ink jet composition.