PVD/Plasma Barrier Coatings for Thermoformed Vacuum Insulation
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Solution Overview
Problem
Existing vacuum insulated structures face challenges in maintaining a consistent vacuum and barrier properties due to limitations in materials and fabrication processes, leading to reduced insulation efficiency in applications such as refrigerator cabinets and doors.
Innovation Solution
A method involving a multi-layer sheet of thermoplastic polymers or elastomeric materials, where at least one layer acts as a barrier between outer layers, thermoformed to create non-planar components, and coated using plasma polymerization or physical vapor deposition to enhance gas barrier properties, with porous filler material and vacuum formation to create an insulated structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials and fabrication processes are used for vacuum insulated structures, then manufacturing is simpler, but barrier properties and vacuum consistency deteriorate
Solution Approach 1:
The patent employs multi-layer composite materials comprising alternating barrier layers and spacer layers. The barrier layers (e.g., PVdC, EVOH, nylon) provide gas and moisture barrier properties, while the spacer layers (e.g., polypropylene, polyethylene) provide structural support and maintain layer separation. This composite structure achieves superior and consistent barrier properties compared to conventional single-layer materials, directly resolving the vacuum consistency issue while remaining manufacturable through standard lamination and thermoforming processes.
2Reliability
If PVD or plasma coating is applied to enhance barrier properties, then gas barrier performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies PVD or plasma coating to the multi-layer sheet material before thermoforming and assembly. This preliminary coating action ensures that the barrier enhancement is already in place before the material undergoes subsequent processing steps. The coating is applied to the flat multi-layer sheet, which simplifies the coating process compared to coating pre-formed three-dimensional components, as the flat surface provides uniform coating distribution and easier process control.
Solution Approach 2:
The PVD or plasma coating is applied to the multi-layer composite material, creating a hybrid composite structure that combines the benefits of the laminated polymer layers with the enhanced barrier properties of the PVD or plasma coating. This composite approach achieves superior gas barrier performance by combining multiple barrier mechanisms (polymer matrix barrier, interface barrier, and PVD/plasma coating barrier) while distributing the complexity across different material systems rather than requiring a single complex material.
3Reliability
If multi-layer barrier materials with PVD or plasma coating are used, then insulation efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The patent segments the barrier function across multiple distinct layers within the multi-layer sheet. Each barrier layer (PVdC, EVOH, nylon) and each spacer layer serves a specific function in the overall barrier system. This segmentation allows each layer to be optimized for its specific purpose and enables the use of standard manufacturing processes for each layer type, reducing overall manufacturing complexity despite the multi-layer structure.
Solution Approach 2:
The multi-layer sheet structure serves multiple functions simultaneously: the barrier layers provide gas and moisture barrier properties, the spacer layers provide structural support and thermal insulation, and the combined structure can be thermoformed into various shapes. This multi-functionality reduces the need for separate components and assembly steps, thereby reducing manufacturing complexity despite the enhanced insulation efficiency achieved through the multi-layer construction.
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 effectively maintains a vacuum and enhances insulation efficiency by blocking gases like nitrogen, oxygen, and water vapor, improving the thermal performance of vacuum insulated structures in refrigerators and other components.
Implementation Method 1
The multi-layer sheet of material is thermoformed to form a non-planar first component
Implementation Method 2
at least one of the first and second outer layers is at least partially coated with a barrier material utilizing a plasma polymerization process
Implementation Method 3
at least one of the first and second outer layers is at least partially coated with a barrier material utilizing a plasma polymerization process or a physical vapor deposition process
Implementation Method 4
a vacuum is formed in the interior space by removing the gaseous components and moisture
Data Source
AI summary
A method of forming a vacuum insulated structure includes providing a multi-layer sheet of material comprising at least one layer of barrier material that is disposed between first and second outer layers. The barrier material and the first and second outer layers comprise thermoplastic polymers. The multi-layer sheet of material is thermoformed to form a non-planar first component. The first component is at least partially coated utilizing a plasma polymerization process or a physical vapor deposition process to improve the barrier properties of the first component. The method further includes securing a second component to the first component to form an interior space therebetween. Porous filler material is positioned in the interior space, and a vacuum is formed in the interior space.