Flame-resistant composite substrates for bituminous membranes
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Solution Overview
Problem
Conventional substrates for bituminous membranes lack adequate mechanical stability, flexibility, and fire-resistant properties, often delaminating, being overly stiff, and posing health and environmental concerns, especially when incorporating glass fibers or metal foils.
Innovation Solution
A porous composite substrate comprising a first and second nonwoven layer of polyester fibers with an intermediate nonwoven layer of organic flame-resistant fibers, providing a high combustion temperature and limiting oxygen index, ensuring mechanical consolidation and efficient impregnation with bitumen while acting as a fire barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass fiber nonwoven layers are used to provide fire resistance, then fire-resistant properties are improved, but flexibility and mechanical stability deteriorate
Solution Approach 1:
The patent changes the material parameter from inorganic glass fibers to organic flame-resistant fibers (such as modacrylic, polyacrylonitrile, or polyphenylene benzo-bisoxazole) that maintain flexibility while providing fire resistance. These organic fibers have combustion temperatures of at least 500°C and LOI values of at least 25%, achieving fire protection without the stiffness and handling difficulties of glass fibers.
Solution Approach 2:
The patent creates a composite substrate combining polyester fibers with organic flame-resistant fibers in a nonwoven structure. This composite material integrates the mechanical properties and flexibility of polyester with the fire-resistant characteristics of the organic flame-resistant fibers, achieving both flexibility and fire protection simultaneously.
2Reliability
If glass fiber nonwoven layers are used to provide fire resistance, then fire-resistant properties are improved, but mechanical stability deteriorates
Solution Approach 1:
The patent changes the fiber material from glass to organic flame-resistant fibers, which have superior mechanical properties. The organic fibers maintain tensile strength and elongation at break comparable to polyester, while providing fire resistance through high combustion temperature (≥500°C) and LOI (≥25%), thereby improving both fire resistance and mechanical stability.
Solution Approach 2:
The composite substrate combines polyester fibers with organic flame-resistant fibers in a nonwoven structure, creating a material that exhibits both the mechanical stability of polyester and the fire-resistant properties of the organic fibers, achieving superior overall performance.
3Reliability
If metal foils are used to provide fire barrier properties, then fire-resistant properties are improved, but ease of manufacture and structural integrity deteriorate
Solution Approach 1:
The patent changes the fire barrier material from metal foils to organic flame-resistant fibers. These fibers have high combustion temperatures (≥500°C) and LOI values (≥25%) that provide effective fire barrier properties, while being compatible with standard nonwoven manufacturing processes, thereby improving ease of manufacture while maintaining fire protection.
Solution Approach 2:
The patent creates a composite nonwoven material combining polyester fibers with organic flame-resistant fibers, integrating fire barrier properties directly into the substrate structure. This eliminates the need for separate metal foil layers and their associated manufacturing complexities, achieving fire protection through material composition rather than layered construction.
4Ease of operation
If conventional organic polymer fiber nonwovens are used, then flexibility and ease of manufacture are improved, but fire-resistant properties deteriorate
Solution Approach 1:
The patent modifies the organic polymer fibers by selecting flame-resistant types (modacrylic, polyacrylonitrile, polyphenylene benzo-bisoxazole) with combustion temperatures of at least 500°C and LOI values of at least 25%. These fibers maintain the flexibility and processability of conventional organic fibers while providing superior fire-resistant properties that conventional organic polymers lack.
Solution Approach 2:
The patent creates a composite nonwoven combining polyester fibers with organic flame-resistant fibers, integrating fire-resistant properties into the organic fiber structure itself. This achieves fire protection through the inherent properties of the flame-resistant organic fibers while maintaining the flexibility and ease of manufacture associated with organic polymer nonwovens.
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 composite substrate offers superior mechanical stability and fire-resistant properties at both room and hot temperatures, preventing delamination and maintaining integrity during bitumen impregnation and application, passing standard fire exposure tests and providing long-term stability in building applications.
Implementation Method 1
an intermediate nonwoven layer comprising organic flame-resistant fibers, wherein a combustion temperature of the organic flame-resistant fibers is at least 500° C. and/or a limiting oxygen index (LOI) of the organic flame-resistant fibers is at least 25%
Data Source
AI summary
A porous composite substrate for producing bituminous membranes, comprising a first nonwoven and a second nonwoven layer which comprise polyester fibers, and an intermediate nonwoven layer comprising organic flame-resistant fibers. A combustion temperature of the organic flame-resistant fibers is at least 500° C. and/or a limiting oxygen index (LOI) of the organic flame-resistant fibers is at least 25%. The composite substrate is mechanically consolidated.