Coated Paperboard Tray Rigidity Overwrapping
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Solution Overview
Problem
Conventional trays for carrying moist food products lack water- and grease-resistance, and the overwrapping process often fails due to insufficient rigidity, while there is a growing trend to limit the use of expanded polystyrene trays.
Innovation Solution
A coated paperboard tray with a single-ply paperboard substrate and a high stiffness barrier coating on one side, providing water- and grease-resistance and sufficient rigidity for overwrapping, made by thermoforming the coated paperboard into a tray shape with a flange for added strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional trays are used for carrying moist food products, then they are simple to manufacture, but they lack water- and grease-resistance and insufficient rigidity for overwrapping
Solution Approach 1:
The patent applies composite materials by combining paperboard substrate with a polymer barrier coating layer. The paperboard provides structural rigidity and formability, while the barrier coating provides water- and grease-resistance. This composite structure resolves the contradiction by achieving both reliability (moisture resistance) and maintaining manufacturing feasibility through coating processes.
Solution Approach 2:
The patent changes the physical-chemical parameters of the paperboard by incorporating internal sizing agents during the papermaking process and applying barrier coatings with specific elastic modulus requirements (at least 1.5 GPa). These parameter changes enhance water- and grease-resistance while maintaining the tray's structural integrity and rigidity for overwrapping applications.
2Strength
If expanded polystyrene trays are used, then they provide sufficient rigidity for overwrapping, but there is a growing trend to limit their use due to environmental concerns
Solution Approach 1:
The patent changes the material parameters by selecting paperboard substrates and barrier coating materials that are compostable and recyclable, while maintaining the required elastic modulus (≥1.5 GPa) for rigidity. This resolves the contradiction by providing an environmentally friendly alternative that meets the mechanical strength requirements for overwrapping applications.
Solution Approach 2:
The patent uses composite materials consisting of paperboard and biodegradable/recyclable barrier coatings, replacing expanded polystyrene. The composite structure achieves the necessary rigidity through the combination of paperboard's structural properties and the barrier coating's mechanical properties, while eliminating the environmental harm associated with polystyrene disposal.
3Reliability
If a barrier coating with high elastic modulus is applied on the food-contact side, then water- and grease-resistance is improved, but the coating may affect the tray's ability to withstand overwrapping forces
Solution Approach 1:
The patent applies local quality by positioning the barrier coating with high elastic modulus (≥1.5 GPa) specifically on the first major side of the paperboard substrate, which corresponds to the inner surface of the tray that contacts food products. This localized application ensures water- and grease-resistance at the food-contact interface while the overall tray structure maintains sufficient strength to withstand overwrapping forces.
Solution Approach 2:
The patent uses composite materials where the paperboard substrate provides the primary structural strength and formability, while the barrier coating layer provides moisture resistance. The composite structure is designed so that the barrier coating's high elastic modulus enhances water- and grease-resistance without compromising the tray's overall ability to withstand overwrapping forces, as the paperboard substrate bears the mechanical loads.
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 coated paperboard tray effectively withstands the overwrapping process and maintains rigidity, while being compostable and recyclable, and allows for printing or dyeing for display purposes.
Implementation Method 1
a barrier coating on the first major side of the single-ply paperboard substrate, the barrier coating having an elastic modulus of at least 1.5 GPa
Implementation Method 2
having an internal sizing agent incorporated therein
Implementation Method 3
thermoforming the paperboard blank between a male die and a female die into a paperboard tray
Data Source
AI summary
A coated paperboard including a single-ply paperboard substrate having a first major side and a second major side, and having an internal sizing agent incorporated therein, and a barrier coating on the first major side of the single-ply paperboard substrate, the barrier coating having an elastic modulus of at least 1.5 GPa.