Liquid EPDM Roofing Membrane for Flexible Installation
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Solution Overview
Problem
Roofing and flashing membranes made of synthetic rubber materials are rigid and difficult to install due to their high tensile strength and low elongation, leading to challenges in achieving a watertight seal around non-standard shapes and roof details.
Innovation Solution
Incorporating a liquid polymer, such as ethylene propylene diene terpolymer (EPDM), with low green strength and high elongation, along with oil-extended and non-oil extended EPDM polymers, to create membranes that can be easily installed and cross-linked post-application, enhancing flexibility and compatibility with TPO membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional synthetic rubber roofing membranes are used, then waterproofing performance is achieved, but installation difficulty increases due to rigidity and high tensile strength
Solution Approach 1:
The patent changes the physical state parameter of the EPDM polymer from solid to liquid at installation conditions, dramatically reducing green strength from typical solid rubber levels to ≤20 lbs force and increasing elongation to ≥400%, making the membrane flexible and easy to install while maintaining waterproofing capability
Solution Approach 2:
The membrane transitions from a static rigid state during storage to a dynamic flexible liquid state during installation, then returns to a stable cured state after cross-linking, allowing the material to adapt its properties to different installation phases
2Strength
If traditional roofing membranes are used, then structural strength is maintained, but flexibility and elongation are reduced making them difficult to conform to roof details
Solution Approach 1:
The patent utilizes parameter changes by controlling the polymer's physical state and molecular weight to achieve ≥400% elongation in liquid form, then restores high tensile strength through cross-linking after installation, allowing the membrane to conform to complex roof geometries while maintaining structural integrity
Solution Approach 2:
The membrane is applied in a preliminary liquid state with high flexibility to conform to roof details and penetrations, then cross-linked in place to achieve final structural strength, reversing the traditional sequence of installing rigid material and then attempting to conform it
3Ease of operation
If liquid polymer with high elongation is used, then ease of installation is improved, but green strength becomes too low to meet ASTM 4811 requirements
Solution Approach 1:
The membrane is installed in a preliminary liquid state with intentionally low green strength (≤20 lbs force) to maximize ease of installation and conformability, then undergoes cross-linking after installation to achieve the required ASTM 4811 tensile strength specifications
Solution Approach 2:
The patent employs phase transition of the EPDM polymer from liquid to cross-linked solid state, where the liquid phase provides installation flexibility with low green strength, and the cross-linked phase provides structural strength meeting code requirements
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 allows for easier installation and improved waterproofing performance by maintaining flexibility during application, preventing thinning when stretched, and ensuring compatibility with TPO membranes, while meeting ASTM 4811 tensile strength requirements post-cross-linking.
Implementation Method 1
The liquid may be a polymer that exists as or remains a liquid at installation conditions until the membrane is cross-linked (e.g., vulcanized or cured)
Data Source
AI summary
A roofing and/or flashing membrane structure that includes a liquid polymer prior to cross-liking is disclosed. The roofing and/or flashing membrane may include additional polymers and have a multi-modal molecular weight distribution. The roofing system can have reduced tensile strength and increased elongation during installation but then strengthen on cross-liking.