Humidity-Responsive Vapor Barrier Coating for Building Substrates

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Solution Overview

Problem

Current vapor retarding building materials fail to maintain desired water vapor permeability across varying relative humidity conditions, particularly at low humidity, and are costly to produce due to complex lamination processes.

Innovation Solution

A vapor retarding article comprising a building material substrate coated with a polymeric layer containing an inorganic hydrophilic particulate filler dispersed in a continuous organic phase of hydrophobic polymer, offering adjustable water vapor permeability based on humidity levels, achieved through a cost-effective coating process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional interior moisture barriers are used, then low water vapor permeability is maintained at low relative humidity, but high water vapor permeability is not achieved at high relative humidity

Engineering Contradiction:

Improvewater vapor permeability controlVSAvoidresponse to varying humidity conditions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The coating layer dynamically adjusts its water vapor permeability in response to changing relative humidity conditions. At low RH, the hydrophobic polymer maintains low permeability, while at high RH, the inorganic hydrophilic filler absorbs moisture and increases permeability, allowing the material to adapt to varying environmental conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention combines a hydrophobic polymer matrix with inorganic hydrophilic filler particles to create a composite coating layer that exhibits dual functionality: moisture blocking at low humidity and moisture transmission at high humidity, resolving the contradiction between maintaining low permeability and achieving high permeability under different conditions.

Inventive Principle:

Principle #40Composite materials

2Reliability

If lamination processes are used to create vapor retarding materials, then desired vapor retarding properties are achieved, but production cost increases and manufacturing complexity increases

Engineering Contradiction:

Improvevapor retarding performanceVSAvoidproduction cost and process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention merges the vapor retarding function and the coating application into a single integrated process. The polymeric coating layer is applied directly to the building material substrate in one step, eliminating the need for separate lamination of pre-manufactured vapor barriers, thereby reducing manufacturing complexity and cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention extracts the vapor retarding functionality from complex multi-layer laminated structures and implements it through a single polymeric coating layer containing specifically selected fillers, simplifying the manufacturing process while maintaining or improving performance.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If polymeric coatings with inorganic hydrophilic filler are used, then variable water vapor permeability is achieved across humidity ranges, but manufacturing precision requirements increase

Engineering Contradiction:

Improvevariable permeability across humidityVSAvoidfiller content control

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The invention utilizes parameter changes in the filler content (within the range of 30-85 wt%) to achieve the desired balance between low RH and high RH performance. By optimizing this parameter, the coating achieves variable permeability while maintaining manufacturability through standard coating processes.

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 provides low water vapor permeability at low relative humidity and high permeability at high relative humidity, effectively managing moisture in building cavities while reducing production costs, thus addressing the limitations of existing materials.

Implementation Method 1

a polymeric coating layer comprising an inorganic hydrophilic particulate filler dispersed in a continuous organic phase comprising a hydrophobic polymer

Methodology Applied

Scientific EffectCapillary condensation: Capillary Condensation

Implementation Method 2

continuous organic phase comprising a hydrophobic polymer

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Data Source

PatentUS11795684B2Vapor retarding building materials and methods for making them

Publication Date: 2023.10.24 CERTAINTEED LLC

AI summary

The present disclosure relates generally to vapor retarding building materials and methods for making them. The present inventors have found simple and cost-efficient materials that have low water vapor permeability at low relative humidities and that can be provided as a coating on a building material substrate. Notably, in many embodiments, the materials can have high water vapor permeability at high relative humidities. In one embodiment, the disclosure provides vapor retarding articles comprising a building material substrate; and a polymeric coating layer coated on the building material substrate, the polymeric coating layer comprising an inorganic hydrophilic particulate filler dispersed in a continuous organic phase comprising a hydrophobic polymer, wherein the content of the filler is from about 30% to about 85% by weight of the polymeric coating layer, the vapor retarding article configured to have a water vapor permeance of no more than about 1 Perm at 25% relative humidity.