Microwavable Ink Composition with Controlled Carbon Black Permittivity
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Solution Overview
Problem
Conventional black inks containing carbon black pigments and nitrocellulose resins used in microwave packaging are prone to ignition, charring, and arcing when exposed to microwave energy, posing safety hazards and failing to provide true black color.
Innovation Solution
Development of a printing ink composition comprising nitrocellulose resin, a solvent, a carbon black pigment with specific imaginary permittivity and surface oxygen content, and a styrene modified maleic anhydride resin, which is safe for microwave use and provides true black color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional black inks containing carbon black pigments and nitrocellulose resins are used in microwave packaging, then the ink provides true black color and good printability, but the ink ignites, chars, and arcs when exposed to microwave energy, creating safety hazards
Solution Approach 1:
The patent changes the chemical parameters of the carbon black pigment by controlling the surface oxygen content (1-5 wt%) and using specific carbon black types (e.g., Cabot Mogul E, Raven 1180) with controlled imaginary permittivity. This parameter modification allows the ink to absorb microwave energy at safe levels while maintaining true black color and nitrocellulose-based printability, resolving the contradiction between safety and harmful effects.
Solution Approach 2:
The patent creates a composite ink system combining nitrocellulose resin with specifically formulated carbon black pigment and additional resins (polyurethane, styrene modified maleic anhydride). This composite formulation synergistically provides both the true black color and microwave safety, eliminating the harmful effects while preserving the beneficial properties of nitrocellulose-based inks.
2Reliability
If trichromatic black inks are used to replace conventional black inks, then safety concerns are reduced, but the color density is insufficient (only 1.3) and the color appears brown rather than true black
Solution Approach 1:
The patent uses carbon black pigment with specifically controlled parameters (surface oxygen content of 1-5 wt%, imaginary permittivity ≤3) to achieve both safety and high color density. This parameter optimization allows the ink to absorb microwave energy safely while providing true black color with density values exceeding 1.3, resolving the contradiction between safety and color intensity.
3Reliability
If carbon black inks with resins other than nitrocellulose are used, then ignition and fire risk are reduced, but the ink lacks the printability and functionality of nitrocellulose-based inks
Solution Approach 1:
The patent modifies the carbon black pigment parameters (surface oxygen content, imaginary permittivity) to enable safe microwave exposure while maintaining compatibility with nitrocellulose resin. This allows the ink to retain the excellent printability and functionality of nitrocellulose-based inks while achieving the safety benefits of alternative resin systems.
Solution Approach 2:
The patent develops a composite formulation combining nitrocellulose resin with specifically controlled carbon black pigment and supplemental resins. This composite structure preserves the superior printability of nitrocellulose-based inks while the modified carbon black pigment ensures microwave safety, resolving the contradiction between safety and ease of manufacture.
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 absorbs microwave energy at safe levels, preventing charring, arcing, ignition, and burning, while achieving a high color density value, ensuring safety and aesthetic superiority in microwaveable packaging.
Implementation Method 1
inks including carbon black pigments and nitrocellulose resins absorb microwave energy and transform same into heat
Implementation Method 2
the inks do not undergo charring, arcing, ignition, distortion and burning of the packaging when exposed to microwave energy
Data Source
Figure 1~2
AI summary
Described herein are printing ink compositions suitable for printing of microwavable flexible packaging. The printed black ink exhibits low microwave energy absorption, thus minimizing the risk of charring, arcing, ignition, distortion or burning during microwave heating processes. Nitrocellulose resin, a solvent, a polyurethane resin, and a carbon black pigment having at least one of an imaginary permittivity of ≤ 3, preferably ≤ 2, and a surface oxygen content of 1wt% to 3wt%, preferably 1.5wt% to 2.5wt% are among the components of the printing ink compositions. Also described is packaging suitable for exposure to microwave energy upon which the inks have been printed.