Bitumen-Polyurethane Granules for UV-Resistant Flexible Membranes
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Solution Overview
Problem
Conventional bituminous membranes used for waterproofing, especially on roofs, face limitations due to the brittleness of conventional bitumens at low temperatures and sensitivity to UV radiation, requiring additional protective measures that increase weight and cost, and existing polyurethane-modified bituminous coatings face challenges in compatibility and stability during industrial synthesis.
Innovation Solution
The development of granules comprising thermoplastic elastomeric polyurethane and bitumen, synthesized through reactive extrusion, which are pre-compatible with a wide range of bitumens, including those with high asphaltene content, allowing for accelerated dispersion and improved stability, reducing synthesis complexity and increasing the usability of average-quality bitumens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bitumen is used for waterproofing membranes, then the membrane provides basic waterproofing, but the bitumen becomes brittle at low temperatures (below -5°C) and loses flexibility
Solution Approach 1:
The patent uses composite materials by combining bitumen with thermoplastic elastomeric polyurethane to create a modified bituminous binder. This composite structure allows the material to maintain flexibility at low temperatures while retaining waterproofing properties, resolving the contradiction between basic waterproofing performance and low-temperature flexibility.
Solution Approach 2:
The patent changes the chemical and physical parameters of bitumen by incorporating polyurethane polymers, which modifies the softening point from around 40°C to above 125°C and improves low-temperature flexibility. This parameter transformation allows the bitumen to perform reliably across an extended temperature range from -40°C to 110°C.
2Strength
If SBS or plastomer polymers are added to modify bitumen, then low-temperature flexibility improves, but UV resistance deteriorates requiring additional protective measures
Solution Approach 1:
The patent uses thermoplastic elastomeric polyurethane that inherently provides UV resistance, eliminating the need for additional protective layers such as metal strips, slate flakes, or mica granules. This single-material solution replaces multiple components (bitumen + polymer + protective layer) with a more efficient composite that resists both low-temperature brittleness and UV degradation.
3Adaptability or versatility
If polyurethane is synthesized in situ in hot bitumen, then modification is achieved, but the process becomes complex and compatibility issues arise especially with high asphaltene content bitumens
Solution Approach 1:
The patent applies preliminary action by pre-synthesizing the thermoplastic elastomeric polyurethane separately before combining it with bitumen. This pre-preparation ensures compatibility and avoids the complexity of in situ synthesis, particularly resolving compatibility issues with high asphaltene content bitumens. The polyurethane is ready for integration without requiring complex reaction control during bitumen processing.
4Object-affected harmful factors
If additional protective layers (metal strips, slate flakes, mica granules) are added to protect against UV, then UV resistance improves, but the membrane weight increases by up to 1.5 kg/m²
Solution Approach 1:
The patent eliminates heavy protective additives (metal strips, slate flakes, mica granules) by using thermoplastic elastomeric polyurethane that inherently provides UV resistance. This reduces the membrane weight by up to 1.5 kg/m² while maintaining or improving UV protection, achieving a lighter and more efficient waterproofing solution.
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 granules enable the production of a bituminous binder with enhanced flexibility and UV resistance, reducing the need for additional protective measures and improving the industrial feasibility of polyurethane-bitumen combinations, resulting in a more efficient and cost-effective waterproofing solution.
Implementation Method 1
granule comprising a thermoplastic elastomeric polyurethane and bitumen
Implementation Method 2
applicable hot: polymerization-crosslinking is done in hot bitumen just before its application on site
Implementation Method 3
polymerization-crosslinking is done in hot bitumen just before its application on site
Implementation Method 4
depositing said bituminous binder on a fibrous support
Data Source
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AI summary
The present invention relates to a granule comprising an elastomeric polyurethane and bitumen, its preparation process in an extruder and its use for preparing a bituminous binder, which can in particular be used to produce prefabricated waterproofing membranes by depositing said bituminous binder on a fibrous support.