Multi-Layer Bottle Structure for Hot-Fill Thermal Contraction
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Solution Overview
Problem
Existing plastic beverage bottles designed for hot-fill processes face challenges in accommodating thermal contraction of contents without requiring thickened walls or movable panels, leading to structural deformation and negative pressure, which affects usability and manufacturing costs.
Innovation Solution
A multi-layer bottle construction with an outer layer thicker than the inner layer, allowing the inner layer to delaminate from the outer layer to accommodate volume reduction during thermal contraction, maintaining the outer layer's shape and structural integrity while preventing negative pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bottle wall is made thicker to accommodate thermal contraction, then structural integrity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The bottle wall is divided into multiple layers (outer layer, intermediate barrier layer, inner layer) that can move independently relative to each other. The inner layer contracts with the beverage while the outer layer maintains its shape, eliminating the need for uniformly thicker walls and reducing manufacturing complexity while preserving structural integrity.
Solution Approach 2:
The bottle employs a composite multi-layer structure where each layer serves a specific function: the outer layer provides structural integrity, the intermediate layer acts as a barrier, and the inner layer accommodates thermal contraction. This composite approach allows the bottle to maintain strength without requiring uniformly thicker walls.
2Adaptability or versatility
If movable panels are added to accommodate volume reduction, then thermal contraction is accommodated, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of adding movable panels, the bottle wall is segmented into multiple independently moving layers. The inner layer moves with the contracting beverage while the outer layer remains stable, providing adaptability to thermal contraction without requiring complex movable panel mechanisms.
Solution Approach 2:
The multi-layer structure enables dynamic behavior where the inner layer can move relative to the outer layer in response to thermal contraction. This dynamic adaptation is achieved through the inherent flexibility of the layered structure rather than through complex mechanical mechanisms.
3Ease of manufacture
If the outer layer is made thinner to reduce material cost, then manufacturing cost decreases, but structural integrity and exterior surface quality deteriorate
Solution Approach 1:
The wall structure is segmented into functional layers where the outer layer can be thinner since it only needs to provide surface integrity and protection, while the inner layer handles the thermal contraction. This segmentation allows cost reduction through optimized thickness distribution without compromising overall structural integrity.
Solution Approach 2:
Different layers of the wall have different thickness characteristics optimized for their specific functions. The outer layer has sufficient thickness for structural and aesthetic purposes, while the inner layer is optimized for accommodating volume changes. This local optimization of quality allows cost reduction while maintaining necessary performance.
4Adaptability or versatility
If negative pressure is applied to initiate delamination, then thermal contraction is accommodated, but internal pressure control becomes more complex
Solution Approach 1:
Negative pressure is applied before filling the beverage to pre-delaminate the layers. This preliminary action prepares the structure to accommodate thermal contraction by creating space between the layers in advance, eliminating the need for complex active pressure control mechanisms during the contraction process.
Solution Approach 2:
The intermediate barrier layer acts as an intermediary that facilitates delamination between the inner and outer layers. This intermediary structure allows the layers to move independently in response to pressure changes and thermal contraction without requiring complex active control mechanisms.
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 solution enables a smooth exterior surface, improved usability, and reduced manufacturing complexity by allowing the bottle to adapt to thermal contraction without deforming the outer layer, while maintaining structural integrity and reducing internal pressure.
Implementation Method 1
cooling the beverage such that the beverage reduces in volume, where the intermediate layer contracts to adapt to the reduced volume
Implementation Method 2
applying a negative pressure relative to ambient pressure to an interior of the beverage bottle before filling the beverage bottle to initiate delamination
Data Source
AI summary
A multi-layer beverage container includes a multi-layer wall having an outer layer, a middle layer, and an inner layer. At least the inner layer is configured to flex inwards to accommodate a change in the sealed internal volume of the beverage container after a hot-filled beverage is filled inside the container and allowed to cool. The outer layer and inner layer delaminate from each other to accommodate this volume change, which allows the outer layer to retain its original shape. The middle layer functions to encourage delamination of the layers with respect to each other. A space corresponding to the volume change of the interior volume of the container is formed between the wall layers.