Fire Resistant Door Cores With Selective Intumescent Coating

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Solution Overview

Problem

Hollow core doors lack the desired weight and insulation properties, and the incorporation of core structures to enhance heat and fire resistance is compromised by recesses formed to accommodate contoured door skins, which can increase heat flow through the door when exposed to fire.

Innovation Solution

A door core with recessed portions coated with fire retardant material, where the material covers no more than 20% of the surface area, and optionally applied to contoured portions of the door skins, to enhance heat and fire resistance without increasing the core thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If recesses are formed in the door core to accommodate contoured door skins, then the door skin contours can be accommodated, but the heat and fire resistance is compromised due to increased heat flow through recessed areas

Engineering Contradiction:

Improvedoor skin contoursVSAvoidheat flow through door

Core Design Contradiction:

ShapeVSObject-affected harmful factors

Solution Approach 1:

The patent applies fire retardant material selectively to the recessed portions of the door core, creating local quality enhancement exactly where the heat flow problem occurs. The coating is applied to cover substantially all of the recessed portions while covering no more than 20% of the remaining major surface area, providing targeted thermal protection without unnecessary material usage on already-thick areas.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If fire retardant material is applied to all surfaces of the door core, then fire resistance is improved, but manufacturing cost and material usage increase

Engineering Contradiction:

Improvefire resistanceVSAvoidfire retardant material

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The patent implements local quality by restricting fire retardant material application to specific recessed portions of the door core rather than coating the entire surface. This selective application ensures adequate fire protection in areas where the core thickness is reduced, while avoiding unnecessary material consumption on areas that already provide sufficient thermal mass.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by coating only the necessary portions (recessed areas) rather than the entire door core surface. The specification that the coating covers no more than 20% of the remaining major surface area demonstrates controlled partial application, achieving adequate fire protection with minimized material usage.

Inventive Principle:

Principle #16Partial or excessive action

3Object-affected harmful factors

If the core structure thickness is increased to improve fire resistance, then heat flow is reduced, but the door weight and material cost increase

Engineering Contradiction:

Improveheat flow through doorVSAvoiddoor weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

Instead of uniformly increasing core thickness throughout, the patent applies local quality enhancement by coating only the recessed portions with fire retardant material. This targeted approach provides necessary thermal protection in areas where thickness is reduced, while maintaining lighter overall door weight by avoiding unnecessary material in already-thick areas.

Inventive Principle:

Principle #3Local quality

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 selective application of fire retardant material in recessed areas of the door core and contoured portions of the door skins improves the door's thermal and fire resistance, meeting or exceeding the resistance of thicker areas, thus enhancing its fire rating without increasing costs.

Implementation Method 1

fire retardant material coating the first recessed portions... improves the door's thermal and fire resistance

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS11781374B2Fire resistant door cores, door skins, and doors including the same

Publication Date: 2023.10.10 IBP SOLUTIONS US LLC

AI summary

A door has a core that includes a first major surface having one or more first recesses, a second major surface opposite to the first major surface, and fire retardant material such as intumescent material applied to the first recesses and no more than about 20 percent by surface area of a remainder of the first major surface excluding the first recesses. A door skin includes an interior surface, an exterior surface, at least one contoured panel portion establishing a protrusion extending on the interior surface and an opposite depression extending into the exterior surface, and fire retardant material such as intumescent material applied to at least one of the protrusion or the depression and no more than about 20 percent by surface area of the remainders of the interior surface excluding the protrusion and the exterior surface excluding the depression.