Polyester Aqueous Inks for Low-Migration Ovenable Packaging
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Solution Overview
Problem
Existing aqueous inks used in flexographic printing fail to provide extended color gamut and thermal resistance suitable for ovenable food packaging, leading to potential contamination from low molecular weight compounds at elevated temperatures.
Innovation Solution
Aqueous printing ink sets using polyester resin binders, particularly sulfopolyester dispersions, with selected pigments, that do not require additional coatings or varnishes, ensuring low migration of compounds at temperatures up to 150°C and beyond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional aqueous inks are used for printing, then the printing process is simple, but the ink set cannot achieve extended color gamut and thermal resistance suitable for ovenable food packaging
Solution Approach 1:
The patent changes the chemical parameters of the ink formulation by using polyester resin binders with specific glass transition temperatures (below 80°C) and specific pigment combinations (CMYK plus additional colors). This allows the ink to achieve extended color gamut while maintaining thermal resistance through controlled polymer chain mobility at elevated temperatures.
Solution Approach 2:
The patent creates a composite ink system combining polyester resin binders with specific pigment combinations. The polyester resin provides both the binding mechanism and the thermal resistance properties, while the pigment combination enables extended color gamut coverage without requiring additional printing passes or layers.
2Ease of manufacture
If conventional inks are used for ovenable packaging, then the printing process is straightforward, but low molecular weight compounds migrate at elevated temperatures causing potential contamination
Solution Approach 1:
The patent modifies the molecular structure parameters of the binder by selecting polyester resins with specific glass transition temperatures below 80°C. This parameter change ensures that at oven temperatures (above 150°C), the polymer chains have sufficient mobility to form a cohesive, low-migration film while maintaining ease of manufacture through conventional printing processes.
Solution Approach 2:
The patent uses a single-layer ink formulation that serves multiple functions simultaneously - binding, color provision, and thermal resistance - eliminating the need for additional protective coatings or varnishes. This reduces the number of manufacturing steps while ensuring low compound migration at elevated temperatures.
3Temperature
If additional coatings or varnishes are applied to achieve thermal resistance, then thermal stability improves, but the number of layers increases reducing sustainability and recyclability
Solution Approach 1:
The patent makes the ink binder itself multi-functional by selecting polyester resins that simultaneously provide binding, color retention, and thermal resistance properties. This eliminates the need for separate protective coatings or varnishes, reducing material usage while achieving the required thermal stability for ovenable packaging.
Solution Approach 2:
The patent merges the functions of the ink binder and the protective coating into a single formulation. The polyester resin binder performs both the adhesion function and the thermal resistance function that would traditionally require separate layers, thereby reducing the total number of material layers and improving sustainability and recyclability.
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 sets achieve an extended color gamut, reducing low molecular weight compound migration to safe levels, suitable for food packaging that can withstand high temperatures without additional layers, enhancing sustainability and recyclability.
Implementation Method 1
the sulfopolyester dispersions preferably used in the present invention have glass transition temperatures significantly lower than required of US 5,369,210. For example, Eastek 1200 (65°C), Eastek 1100 (55°C), Eastek 1300 (36°C), Eastek 1400 (29°C), all ex. Eastman. Thus, a further aspect of the present invention is the use of sulfopolyester dispersions having glass transition temperatures of less than 80°C.
Data Source
AI summary
The present invention relates to a method of providing a packaged food product comprising printing a substrate with an aqueous printing ink composition, drying said ink composition to provide a printed substrate and packaging a food stuff with said printed substrate, wherein the method excludes printing or applying any layers over the dried ink composition, wherein the ink composition comprises water and polyester resin. The present invention also relates to use of an aqueous printing ink for printing on a substrate, wherein the printed substrate has less than 50 ppb migratable species when heated to temperatures in excess of 150°C, wherein the aqueous ink composition comprises water and polyester resin.