Non-Woven Substrate for Bituminous Membranes Using Mixed Fiber Carding
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Solution Overview
Problem
Existing substrates for bituminous membranes face challenges in achieving high mechanical strength, dimensional stability, and fire resistance while minimizing weight and material usage, with previous methods requiring expensive processes and high fiber lengths, which can compromise mechanical strength and adhesion points.
Innovation Solution
A substrate is created by mixing organic and inorganic staple fibers through repeated opening and blending during the carding process, combining layers with a reinforcing scrim, consolidating via hydroentangling, drying, and heat setting, with a binder application to achieve improved mechanical strength and fire resistance while reducing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the mass of the non-woven fabric is increased to meet ultimate tensile strength requirements in the transversal direction, then the mechanical strength is improved, but the weight increases
Solution Approach 1:
The patent applies composite materials by combining organic fibers (polyester, polypropylene) with inorganic fibers (glass, basalt) in a non-woven fabric structure. This composite approach allows the fabric to achieve high mechanical strength properties, particularly ultimate tensile strength in both longitudinal and transversal directions, while maintaining lower weight compared to using solely dense inorganic materials. The synergistic combination of fiber types provides both strength and weight efficiency.
Solution Approach 2:
The patent implements local quality by creating a heterogeneous fiber distribution where different fiber types are strategically positioned within the non-woven fabric. The mixture of organic and inorganic fibers with different properties creates zones of varying characteristics - areas with higher inorganic fiber content for strength and areas with organic fibers for flexibility and weight reduction. This local variation optimizes the overall performance-to-weight ratio.
2Strength
If carding machines and pre-needling machines are arranged in the transversal direction to comply with mechanical features, then the mechanical strength is improved, but the device complexity and production cost increase
Solution Approach 1:
The patent extracts the function of mechanical consolidation from complex carding and pre-needling machines by directly forming the non-woven fabric with the required fiber orientation and density during the initial carding process. The fiber mixture is carded and laid in a specific arrangement that inherently provides the necessary mechanical properties without requiring subsequent complex consolidation equipment. This removes the need for expensive and complex transversal carding and pre-needling machines.
Solution Approach 2:
The patent replaces complex mechanical consolidation systems (carding machines, pre-needling machines) with a simplified carding and laying process that achieves the same mechanical properties through fiber arrangement and distribution. The mechanical strength is achieved through the intrinsic structure of the fiber matrix rather than through complex mechanical interlocking devices, thereby reducing device complexity.
3Ease of manufacture
If wet processing is used to produce substrates from glass fibers, then the production process is simplified, but the mechanical strength decreases due to limited fiber adhesion points
Solution Approach 1:
The patent uses composite materials by combining hydrophilic glass fibers with hydrophobic organic fibers (polyester, polypropylene) in a dry non-woven process. This composite structure compensates for the limitations of wet processing - the organic fibers provide additional adhesion points and structural support while the glass fibers contribute strength and stiffness. The combination maintains mechanical strength comparable to or exceeding wet-processed substrates while avoiding the fiber clumping and adhesion issues associated with wet processing.
Solution Approach 2:
The patent replaces the wet processing mechanical system with a dry carding and laying system. Instead of using water dispersion and suction mat consolidation, the invention uses mechanical carding to separate and randomly distribute fibers, followed by laying and needling to consolidate the structure. This dry mechanical approach prevents fiber clumping, maintains individual fiber adhesion points, and achieves superior mechanical strength while simplifying the production process by eliminating drying and resin consolidation steps.
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 results in a substrate with enhanced mechanical strength, dimensional stability, and fire resistance, achieving a better weight-to-performance ratio, reduced binder usage, and improved recyclability, while minimizing environmental impact and raw material consumption.
Implementation Method 1
the layers-scrim 3, 4 complex is then consolidated by means of hydroentangling
Implementation Method 2
dried, thermally stabilized
Data Source
Figure 1
AI summary
There is described a substrate (1) for a support (1) for bituminous membranes, comprising two or more layers of fibers (3) comprising a homogeneous mixture of organic fibers (31) and inorganic fibers (32), between which there is interposed a reinforcing scrim (4), said fibers (3) being oriented parallel to the longitudinal axis (L) of the substrate (1) and laid said by side and alternate.