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, or posing health and environmental concerns, which compromises their sealing and fire-barrier effectiveness.
Innovation Solution
A composite substrate comprising a first and second nonwoven layer of polyester fibers with an intermediate nonwoven layer of organic flame-resistant fibers, which are inherently flame-resistant with a high combustion temperature and limiting oxygen index, ensuring mechanical stability and flexibility at both room and hot temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass fiber nonwoven layers are used to provide fire resistance, then fire barrier properties are improved, but mechanical stability and flexibility deteriorate
Solution Approach 1:
The patent changes the material parameter from inorganic glass fibers to organic flame-resistant fibers (such as modacrylic, polyacrylonitrile, or aramid fibers) that maintain flexibility while providing fire resistance. These organic fibers have inherent flame resistance with combustion temperatures above 500°C and LOI values above 25%, achieving fire barrier properties without the excessive stiffness 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 stability of polyester with the fire resistance of organic flame-resistant fibers, achieving both fire barrier properties and adequate mechanical strength without delamination.
2Reliability
If metal foils are incorporated to confer fire barrier properties, then fire resistance is improved, but ease of manufacture and structural integrity worsen
Solution Approach 1:
The patent changes from metal foil materials to organic flame-resistant fiber materials. These organic fibers inherently resist combustion with high combustion temperatures and LOI values, providing fire barrier properties without the manufacturing difficulties, delamination issues, and structural damage problems associated with metal foils.
3Reliability
If glass staple fibers are used for fire resistance, then fire barrier properties are improved, but health and environmental safety deteriorate
Solution Approach 1:
The patent changes from inorganic glass staple fibers to organic flame-resistant fibers. These organic fibers (modacrylic, polyacrylonitrile, aramid) provide the same fire barrier protection without the high irritation risk associated with glass fibers, improving health and environmental safety while maintaining fire resistance.
Data Source
Figure 1~2
AI summary
Subject of the invention is 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, wherein the composite substrate is mechanically consolidated. Subject of the invention are also production methods, bituminous membranes comprising such composite substrates and uses of flame-resistant fibers.