Bonded Door Leaf Structure for Fire-Stable Sound Insulation

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Door leaves or door blanks often exhibit high sound permeability and inadequate fire protection properties, with significant warping during fires, making larger formats impractical due to weight and safety concerns, especially in soundproof doors where loose layers can detach and become unsafe.

Innovation Solution

A door leaf or door blank with a core layer and sheet material layers bonded together using adhesive agents like PU, PVAc, or EPI, incorporating intumescent coatings for fire protection and sound insulation, and edge banding for structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If door leaves use loose layers for soundproofing, then sound insulation is improved, but fire protection properties deteriorate due to warping and detachment

Engineering Contradiction:
Improvesound permeabilityVSAvoidfire protection properties
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent combines multiple layers (sheet material layers and core layers) into a single bonded structure using adhesive areas, eliminating the loose layer configuration. This merging ensures that all layers move together as one unit during fire exposure, preventing detachment while maintaining sound insulation properties through the layered construction.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses composite material construction with at least one core layer made of different materials (such as wood fiber board, particle board, or hollow core) sandwiched between sheet material layers. This composite structure provides both sound insulation through material diversity and fire resistance through the bonded configuration that prevents warping and detachment.

Inventive Principle:
Principle #40Composite materials

2Productivity

If door leaves are made with larger formats, then productivity is improved, but weight increases making them impractical

Engineering Contradiction:
Improvedoor format sizeVSAvoiddoor weight
Core Design Contradiction:
ProductivityVSWeight of moving object

Solution Approach 1:

The patent employs hollow core layers or core layers with porous structures (such as wood fiber board or particle board) that provide structural integrity and fire resistance while significantly reducing weight compared to solid wood construction. This allows for larger door formats to be manufactured without excessive weight increases.

Inventive Principle:
Principle #31Porous materials

3Stability of the object's composition

If adhesive areas are provided to bond layers, then structural integrity is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvelayer bondingVSAvoidmanufacturing process
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent divides the bonding function into discrete adhesive areas rather than requiring continuous bonding across entire surfaces. These adhesive areas can be positioned at specific locations (such as at the edges or at intervals) to provide sufficient structural integrity while simplifying the manufacturing process and reducing adhesive application complexity.

Inventive Principle:
Principle #1Segmentation

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 provides excellent fire protection and sound insulation, maintaining stability during fires and improving soundproofing capabilities, suitable for large-format doors with minimal surface waviness and enhanced safety.

Implementation Method 1

at least one adhesive area is provided on the mutually facing surfaces of the core layer and/or the sheet material layers, in which the mutually facing layers are bonded or glued together, in particular by means of at least one adhesive agent based on PU (polyurethane) or on PVAc (polyvinyl acetate) or on EPI (emulsion polymer isocyanate) or on at least one silane-modified polymer (silane)

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

incorporating intumescent coatings for fire protection

Methodology Applied
Scientific EffectIntumescent expansion: Intumescent Materials

Data Source

PatentEP4707521A1Door leaf or door blank
Publication Date: 2026.03.11 MORALT
  • EP4707521A1 patent drawingFigure 1A~1D
  • EP4707521A1 patent drawingFigure 2~3
  • EP4707521A1 patent drawingFigure 4~5A

AI summary

To provide a door leaf or a door blank (101, 102, 103, 104, 105) thatThe following features are proposed for a material that is characterized by both high airborne sound insulation and very good fire protection properties: - at least one core layer (10, 12), in particular acoustic, - at least one first layer of panel material (50) associated with a surface of the core layer (10, 12), - at least one second layer of panel material (52) associated with the core layer (10, 12) on its surface facing away from the first layer of panel material (50), wherein at least one adhesive area (20) is provided on the mutually facing surfaces of the core layer (10, 12) and/or the layers of panel material (50, 52), in which the mutually facing layers (50; 10, 12; 52) are bonded or glued together, in particular by means of at least one adhesive agent based on PU (polyurethane) or on PVAc (polyvinyl acetate) or based on EPI (emulsion polymer isocyanate) or based on at least one silane-modified polymer (silane).