Foam Insulation Cavity Filling with Low Pressure Blowing Agents

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Solution Overview

Problem

Existing methods for retrofitting insulation into hollow exterior walls, such as using polyurethane or polyisocyanurate foams, face challenges like damage to drywall, difficulty in flowing around obstructions, and uneven density, leading to inefficient energy conservation and potential structural issues.

Innovation Solution

A process using low-pressure, high-boiling-point blowing agents in a two-component polyurethane or polyisocyanurate foam system that expands without damaging drywall, flows around obstructions, and maintains uniform density, with a reaction profile that allows for quick gel and tack times, enhancing structural integrity and energy efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polyurethane or polyisocyanurate foams are used to fill wall cavities, then insulation effectiveness is improved, but the foam expansion pressure causes damage to drywall and wall structures

Engineering Contradiction:

Improveinsulation effectivenessVSAvoiddamage to drywall

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical and chemical parameters of the foam system by using a two-component formulation with specific catalysts and blowing agents that control the expansion rate. This allows the foam to expand slowly and uniformly, reducing peak expansion pressure while maintaining insulation effectiveness. The gel time is optimized to be shorter than rise time, ensuring structural integrity during expansion.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a dynamic expansion process where the foam's gel time and tack time are carefully controlled to be shorter than the rise time. This dynamic timing sequence allows the foam to gain sufficient structural strength during expansion to support itself without causing excessive pressure on wall structures, while still achieving complete cavity fill.

Inventive Principle:

Principle #15Dynamics

2Reliability

If conventional insulation materials are used for retrofitting, then insulation is provided, but extensive building damage and reconstruction are required

Engineering Contradiction:

Improveinsulation provisionVSAvoidinstallation complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses a pneumatic delivery system to inject the two-component foam mixture through a small access hole into the wall cavity. The foam is delivered under controlled pressure through hoses, allowing installation without extensive building demolition. The pneumatic system enables the foam to flow around obstructions and fill the entire cavity through minimal intrusion.

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent creates local access points (small holes) in the wall rather than requiring extensive demolition. The foam is injected through these localized access points and expands to fill the entire cavity, providing complete insulation while preserving the majority of the existing wall structure.

Inventive Principle:

Principle #3Local quality

3Strength

If foam with short gel time is used, then structural integrity is improved, but the foam may not have time to expand fully before setting

Engineering Contradiction:

Improvestructural integrityVSAvoidfoam expansion volume

Core Design Contradiction:

StrengthVSVolume of moving object

Solution Approach 1:

The patent establishes a dynamic sequence where gel time and tack time are both shorter than rise time. This creates an optimal window where the foam gains sufficient structural strength to support its own weight and prevent sagging, while still maintaining enough flexibility to continue expanding and filling the entire cavity volume.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent adjusts multiple parameters including catalyst concentration, blowing agent type and amount, and component ratio to achieve the desired timing sequence. These parameter changes ensure that the foam develops adequate strength during expansion while completing full cavity fill, optimizing both structural integrity and expansion volume.

Inventive Principle:

Principle #35Parameter changes

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 effectively fills wall cavities with minimal damage, ensuring a continuous air barrier and improved energy efficiency by maintaining uniform density and structural integrity, reducing energy costs and labor costs associated with multiple drill holes.

Implementation Method 1

adding a two-component polyurethane or polyisocyanurate foam to said cavity, said foam comprising an effective amount of at least one blowing agent

Methodology Applied

Scientific EffectGas generation through chemical reaction: Chemical Bonding

Implementation Method 2

said foam system having a reaction profile gel and tack time which is less than approximately 90 seconds

Methodology Applied

Scientific EffectPhase transition during foaming: Phase Change

Data Source

PatentUS8680168B2Method for filling wall cavities with expanding foam insulation

Publication Date: 2014.03.25 ICP CONSTRUCTION INC

AI summary

The invention is the use of low boiling point, low vapor pressure blowing agents with froth polyurethane or polyisocyanurate foams to fill cavity voids when compared to higher vapor pressure or more ozone-depleting blowing agents.