Actinic-Curable Offset Ink Without Photosensitizer
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Solution Overview
Problem
Actinic ray-curable inks used for foodstuff and pharmaceutical packaging face challenges in suppressing outward migration of (meth)acrylate monomers and photopolymerization initiators, which are critical components, while maintaining high curability and substrate adhesion, especially without the use of photosensitizers.
Innovation Solution
The development of an actinic ray-curable offset ink composition that includes a photopolymerization initiator comprising acylphosphine oxide, α-aminoalkylphenone, and α-hydroxyalkylphenone compounds, with specific molar extinction coefficients and molecular weight ranges, and (meth)acrylate monomers with multiple acrylate functional groups, all without using a photosensitizer, to achieve efficient curing and low migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If photosensitizer is used to improve curability, then productivity is improved, but outward migration of ink components increases
Solution Approach 1:
The patent changes the chemical parameters of the photopolymerization initiator by selecting specific compounds with defined molecular weight ranges (200-500 g/mol) and specific structural classes (acylphosphine oxide, α-aminoalkylphenone, α-hydroxyalkylphenone). This parameter optimization enables efficient curing without photosensitizer while controlling migration, resolving the contradiction between curability and migration suppression.
Solution Approach 2:
The patent extracts and eliminates the photosensitizer component from the ink formulation. By removing this harmful element and relying solely on optimized photopolymerization initiators, the system achieves both good curability and reduced outward migration, directly resolving the technical contradiction.
2Object-generated harmful factors
If molecular weight of photopolymerization initiator is increased to reduce migration, then outward migration is suppressed, but curability deteriorates
Solution Approach 1:
The patent identifies and applies the optimal molecular weight parameter range of 200-500 g/mol for photopolymerization initiators. This specific parameter range balances two opposing requirements: low enough molecular weight to ensure good curability and reactivity, yet high enough to suppress outward migration. The patent demonstrates that initiators within this range achieve both goals simultaneously.
3Reliability
If strict migration limits are imposed to meet safety standards, then safety is improved, but ink design complexity increases
Solution Approach 1:
The patent establishes specific parameter specifications for ink components, including photopolymerization initiators with molecular weights of 200-500 g/mol and (meth)acrylate monomers with 3 or more functional groups and molecular weights of 400-2000 g/mol. These clear parameter guidelines provide a straightforward design framework that ensures compliance with safety standards while simplifying the ink formulation process.
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
This composition ensures superior curability and effective suppression of outward migration, meeting safety standards equivalent to or exceeding Swiss Ordinance (RS817.023.21), while maintaining high productivity and adhesion, even without a photosensitizer.
Implementation Method 1
actinic ray-curable inks include an unsaturated compound having actinic ray curability such as an acrylate ester compound as an ink component, and cure instantaneously upon irradiation with actinic rays, with a three dimensional crosslinking reaction of the unsaturated compound forming a tough coating film
Data Source
Figure 1
AI summary
The invention provides an actinic ray-curable offset ink composition for foodstuff and pharmaceutical packaging which maintains superior curability without using a photosensitizer, which despite contributing to better curability (high productivity) tends to suffer from significant outward migration. The ink composition also suppresses outward migration of the monomers and photopolymerization initiators, and exhibits favorable adhesion to substrates.