Low Migration Radiation Curable Inks via Alkoxylated Monomers
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Solution Overview
Problem
Existing radiation curable ink and coating compositions face challenges in achieving high monomer conversion during curing, leading to residual unbound monomers that can migrate into sensitive products like food and pharmaceuticals, which is a concern for packaging applications.
Innovation Solution
Incorporating highly alkoxylated monomers or oligomers with at least 2 polymerizable groups per molecule and a degree of alkoxylation of 3 or greater, along with specific concentrations of photoinitiators and monofunctional monomers, to enhance monomer conversion and reduce unbound monomer migration in low migration radiation curable ink or coating compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional radiation curable ink compositions are used, then the curing process is simple, but monomer conversion is incomplete leading to residual unbound monomers that can migrate
Solution Approach 1:
The patent changes the chemical parameters of the monomers by using highly alkoxylated monomers with specific molecular structures (degree of alkoxylation ≥3). This parameter change increases the monomer conversion degree during curing from conventional levels to above 90%, thereby reducing unbound monomer migration into packaged goods.
Solution Approach 2:
The patent employs composite monomer systems combining highly alkoxylated monomers (with degree of alkoxylation ≥3) with specific photoinitiators and optional monofunctional monomers. This composite approach creates a synergistic effect that achieves high monomer conversion while maintaining proper curing characteristics and minimizing harmful migration.
2Object-generated harmful factors
If highly alkoxylated monomers are used to increase monomer conversion, then unbound monomer migration is reduced, but the composition complexity increases
Solution Approach 1:
Rather than complicating the composition with multiple components, the patent achieves its goal by changing the key parameter of the main monomer structure - using highly alkoxylated monomers with degree of alkoxylation ≥3. This single parameter change in the monomer selection effectively reduces unbound monomer migration while keeping the composition relatively simple.
3Manufacturing precision
If high concentration of photoinitiators is used to ensure complete curing, then monomer conversion increases, but the risk of photoinitiator migration and contamination increases
Solution Approach 1:
The patent changes the photoinitiator concentration parameter to an optimized range (0.1-7% w/w) rather than using high concentrations. Combined with the use of highly alkoxylated monomers that achieve high conversion efficiency, this parameter change ensures complete curing while minimizing photoinitiator migration risk.
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 use of highly alkoxylated monomers significantly increases monomer conversion during curing, resulting in reduced levels of unreacted monomers that can migrate, thereby ensuring the safety and integrity of packaged goods by minimizing contamination from inkjet inks and coatings.
Implementation Method 1
radiation curable ink or coating composition... one or more type-I photoinitiators... polymerizable monomers or oligomers having an alkoxylated chain and at least 2 polymerizable groups per molecule
Implementation Method 2
ethoxylated monomers have been used in low migration UV-curable coating applications as H-transfer co-initiators in combination with type-2 photoinitiators
Data Source
AI summary
The present invention provides low migration radiation-curable inks and coatings for the printing of food, pharmaceutical and other sensitive packaging materials, having one or more polymerizable monomers or oligomers and one or more type-I photoinitiators wherein the monomers or oligomers have an alkoxylated chain and at least 2 polymerizable groups per molecule and wherein the degree of alkoxylation per polymerizable group is 2 or greater.