Segmented Door Leaf with Intumescent Edge for Fire and Sound
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Solution Overview
Problem
Door leaves or door blanks often have high sound permeability and inadequate fire protection properties, limiting their size due to torsion and weight issues during fires.
Innovation Solution
A door leaf or door blank design featuring a layered structure with a first and second acoustic core layer, chipboard layers, softwood layers, and an intumescent-coated edge strip, using polyurethane-based adhesives and urea-formaldehyde adhesives for enhanced sound insulation and fire resistance, without a frame frieze.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If door leaves or door blanks are made with conventional single-layer structures, then manufacturing is simpler, but sound insulation is insufficient
Solution Approach 1:
The door leaf is divided into multiple acoustic core layers (first acoustic core layer and second acoustic core layer) with different densities, separated by adhesive layers. This segmentation creates a multi-layered structure that improves sound insulation by disrupting sound wave transmission through varying density interfaces, while maintaining manufacturability through standardized layering processes.
Solution Approach 2:
The door leaf employs composite material construction with acoustic core layers of different densities (lighter and denser acoustic core layers), chipboard layers, softwood layers, and adhesive layers (including polyurethane-based adhesives). This composite structure achieves superior sound insulation by combining materials with different acoustic impedances, creating multiple reflection and absorption interfaces for sound waves.
2Area of stationary object
If door leaves or door blanks are made with larger formats, then coverage area is improved, but fire protection properties deteriorate due to warping
Solution Approach 1:
The door leaf is segmented into multiple thin layers (acoustic core layers, chipboard layers, softwood layers, adhesive layers) rather than using a single thick panel. This segmentation reduces internal stresses and prevents warping during fire exposure, allowing larger door formats to maintain structural integrity and fire protection properties.
Solution Approach 2:
The multi-layer composite structure with alternating densities and material types (acoustic core layers, chipboard, softwood, polyurethane adhesives) creates a balanced construction that resists thermal expansion and warping during fire. The diverse material composition provides thermal stability and structural reliability for large-format doors in fire conditions.
3Area of stationary object
If door leaves or door blanks are made with larger formats, then coverage area is improved, but weight increases making them impractical
Solution Approach 1:
The door leaf is divided into multiple thin layers including lighter acoustic core layers and denser acoustic core layers, chipboard layers, and softwood layers separated by adhesive layers. This segmentation allows optimization of each layer's thickness and density, achieving large surface area coverage while controlling overall weight through the use of lighter materials in non-critical areas.
Solution Approach 2:
The composite structure combines materials with different densities (lighter acoustic core layer, denser acoustic core layer, chipboard, softwood, polyurethane adhesives) to achieve optimal weight-to-area ratio. The lighter materials provide sufficient acoustic and fire protection for large formats without excessive weight, while denser materials are strategically placed for enhanced performance where needed.
4Ease of manufacture
If conventional adhesives are used between layers, then manufacturing cost is reduced, but fire resistance deteriorates
Solution Approach 1:
The adhesive material is changed from conventional adhesives to polyurethane-based adhesives (including heat-resistant white adhesives, starch adhesives, and low-formaldehyde dispersion adhesives). This parameter change in adhesive chemistry provides superior fire resistance and thermal stability while maintaining acceptable manufacturing costs through efficient application processes and material performance.
Solution Approach 2:
The adhesive layers use specialized polyurethane-based adhesives that form part of the composite material system, providing fire resistance that complements the fire-resistant properties of the acoustic core layers, chipboard, and softwood. These adhesives maintain bond strength at elevated temperatures, ensuring structural integrity during fire exposure.
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 design achieves high airborne sound insulation and excellent fire protection, allowing for larger formats with improved stability and fire resistance, effectively preventing sound and flame transmission.
Implementation Method 1
the edge trim or banding can be coated with at least one intumescent coating, in particular be carbon-based
Implementation Method 2
the adhesive between the first acoustic core layer and the second acoustic core layer may be polyurethane (PU) based, in particular a heat-resistant white or starch adhesive or a low-formaldehyde dispersion adhesive
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
To provide a door leaf or door blank that is characterized by both high airborne sound insulation and very good fire protection properties, the following features are proposed: - a first acoustic core layer (10), - a second acoustic core layer (12) associated with the first acoustic core layer (10), - a first chipboard layer (20) associated with the first acoustic core layer (10), - a second chipboard layer (22) associated with the second acoustic core layer (12), - a first softwood layer (30) associated with the first chipboard layer (20), - a second softwood layer (32) associated with the second chipboard layer (22), - a third chipboard layer (24) associated with the first softwood layer (30), and - a fourth chipboard layer (26) associated with the second softwood layer (32), wherein the individual layers and layers are glued together.