Evacuated Closed Cell LDPE Foam Thermal Insulation
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Solution Overview
Problem
There is a need in the industry to develop closed cell expanded low density polyethylene foam with superior thermal insulation characteristics and a process to achieve this.
Innovation Solution
A process involving a mixture of low density polyethylene pellets and glycerides as a degassing agent, with a primary blowing agent such as liquid propane or butane, is used to expand and cure the polyethylene, resulting in evacuated closed cell low density polyethylene sheets with at least 99% dissipation of the blowing agent, enhancing thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional foaming processes are used to produce expanded LDPE foam, then the foam structure is formed, but the thermal insulation characteristics are insufficient
Solution Approach 1:
The patent creates a vacuum environment by removing the blowing agent from the foam cells, creating an inert atmosphere that significantly improves thermal insulation. The evacuation of cells to remove blowing agent creates a vacuum structure that acts as effective insulation, directly addressing the insufficient thermal insulation characteristics of conventional foamed LDPE.
Solution Approach 2:
The patent utilizes a porous foam structure with evacuated cells to achieve superior thermal insulation. The closed-cell foam structure with removed blowing agent creates a vacuum-filled porous material that provides enhanced thermal resistance compared to conventional foam structures that retain their blowing agents.
2Reliability
If blowing agent is retained in the foam cells, then the foam structure is maintained, but thermal resistance is reduced
Solution Approach 1:
The patent applies the extraction principle by removing the blowing agent from the foam cells through a curing process that allows at least 99% dissipation of the blowing agent. This extraction of the blowing agent from the closed cells creates the vacuum structure that provides superior thermal insulation while maintaining the foam's structural integrity.
Solution Approach 2:
The patent discards the blowing agent from the foam structure during the curing process, allowing it to dissipate from the cells. This discarding of the blowing agent is intentional and necessary to achieve the vacuum structure that provides enhanced thermal resistance, transforming the foam from a conventional insulator to a vacuum-insulated material.
3Loss of substance
If glycerides are added as a degassing agent, then blowing agent dissipation is enhanced, but the process complexity increases
Solution Approach 1:
The patent employs glycerides as a degassing agent that facilitates the self-service removal of blowing agent from the foam cells during curing. The glycerides enable the blowing agent to dissipate naturally without requiring additional complex equipment or processes, achieving at least 99% dissipation through a relatively simple curing step that maintains process feasibility.
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 process produces foamed polyethylene with superior thermal insulation properties, achieving high thermal resistance and flexibility, suitable for applications like composite house wraps and fabrics, with the ability to form a vacuum structure that acts as effective insulation.
Implementation Method 1
adding a primary blowing agent comprising one of liquid propane, liquid butane, and combinations thereof, to the mixture and gasifying the blowing agent to expand the low density polyethylene
Implementation Method 2
gasifying the blowing agent to expand the low density polyethylene
Implementation Method 3
providing a mixture including low density polyethylene pellets and an effective amount of glycerides as a degassing agent
Implementation Method 4
curing the expanded low density polyethylene until 99% of the primary blowing agent is dissipated from cells within the expanded low density polyethylene
Implementation Method 5
The process produces foamed polyethylene with superior thermal insulation properties, achieving high thermal resistance
Implementation Method 6
forming evacuated closed cell low density polyethylene sheets... with the ability to form a vacuum structure that acts as effective insulation
Data Source
AI summary
The process for forming closed cell expanded low density polyethylene foam includes the steps of: providing a mixture including low density polyethylene pellets and an effective amount of hydrocarbon scavenger additives or degassing agents, such as glycerides; adding a primary blowing agent comprising one of liquid propane, liquid butane, and combinations thereof, to the mixture and gasifying the blowing agent to expand the low density polyethylene; forming the expanded low density polyethylene into sheets, curing the expanded low density polyethylene until 80%, generally at least 99%, of the primary blowing agent is dissipated from cells within the expanded low density polyethylene forming evacuated closed cell low density polyethylene sheets.