Rolled Tray Edges for Film-Safe Thermoplastic Sealing
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Solution Overview
Problem
Existing thermoplastic articles often have sharp edges that can damage sealing films or injure flesh, and are not suitable for multiple sealing technologies like OW, VSP, and MAP, posing challenges in packaging and recycling.
Innovation Solution
A method to form a smooth edge by creating a deflectable flange at the edge of a thermoplastic article, deflecting the sharp edge inward and locking it in place using heat or pressure, making the edge hidden from contact with external materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If trimming of waste material is performed on edges of shaped articles, then the article can be formed from thermoplastic material, but a sharp edge is left that can injure flesh or tear materials contacting the edge
Solution Approach 1:
The patent applies curvature by rolling the sharp edges of the thermoplastic article into a rounded configuration. This curved edge profile eliminates the sharp corners and points that cause injury or damage to materials, while still maintaining the structural integrity of the article. The rolling process creates a smooth, rounded edge that is safe for contact.
Solution Approach 2:
The patent changes the physical state of the thermoplastic material by applying heat to specific regions before rolling the edges. This thermal parameter change softens the material, allowing it to be deformed into a rounded configuration. After rolling, the material is cooled to set the new rounded edge shape permanently.
2Ease of manufacture
If sharp edges are present on containers, then the container structure is simple and easy to manufacture, but the film used for sealing can be cut or broken by the edge
Solution Approach 1:
The patent rounds the edges of the container to eliminate sharp corners and points that would cut or break sealing film. The curved edge profile maintains structural simplicity while protecting the integrity of the sealing film during the sealing process and throughout storage and handling.
Solution Approach 2:
The patent performs the edge rolling and rounding operation during the manufacturing process itself, before the container is used for sealing. This preliminary action pre-empts the potential damage to sealing film by eliminating sharp edges before they can cause harm during subsequent sealing operations.
3Object-affected harmful factors
If foamed trays or bins are used to avoid sharp edges, then the edges are safe for contact, but the materials are excluded from recycling programs and disfavored by consumers
Solution Approach 1:
The patent changes the physical state of the thermoplastic material through controlled heating and rolling, creating a rounded edge configuration that is safe for contact. This approach maintains the use of conventional thermoplastic materials (which are recyclable and consumer-friendly) while achieving the safety benefit of rounded edges, eliminating the need to resort to foamed materials.
Solution Approach 2:
The patent replaces the mechanical/chemical foam formation process with a thermal and mechanical rolling process. Instead of using foamed materials to achieve safe edges, the patent applies heat and mechanical rolling to conventional thermoplastic materials, achieving the same safety outcome while maintaining recyclability and consumer acceptance.
4Adaptability or versatility
If multiple sealing technologies (OW, VSP, MAP) are to be used, then versatility is improved, but the container design becomes more complex
Solution Approach 1:
The patent creates a universal edge design by rolling and rounding all edges of the container to a consistent curved profile. This standardized rounded edge configuration is compatible with multiple sealing technologies (OW, VSP, MAP) because it provides a safe, non-damaging surface for film contact in each sealing method, achieving multi-functionality without requiring different edge designs for each technology.
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 method effectively reduces the risk of film damage and injury, enabling the article to be used with various sealing technologies and improving recyclability.
Implementation Method 1
softening the bent portion at least while the flange is in the deflected position
Implementation Method 2
cooling the softened and deflected deflectable flange below its glass transition temperature
Implementation Method 3
softening the bent portion at least while the flange is in the deflected position
Implementation Method 4
cooling the softened and deflected deflectable flange below its glass transition temperature
Data Source
AI summary
The disclosure relates to forming shaped thermoplastic articles having smooth peripheries. Many thermoplastic articles have sharp edges formed upon molding or cutting the article from a feedstock sheet. Such sharp edges can damage thin plastic films or flesh which they contact, and smoothing the edges is desirable. Described herein are methods of forming a smooth periphery for such sharp-edged articles by rolling over the sharp edge. The smoothing operation is performed by forming a deflectable flange including a bend region separated from the potentially sharp peripheral edge by a spacer, deflecting a portion of the deflectable flange, and softening at least one bent portion of the deflectable flange to yield a smooth periphery upon cooling.