Coating compositions for building materials and coated building material substrates
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Solution Overview
Problem
Current building materials coatings fail to maintain desired water vapor permeance at low relative humidity and are not suitable for porous substrates, such as nonwovens, due to off-gassing of volatile organic compounds and instability in water vapor permeance across varying humidity levels.
Innovation Solution
A coating composition combining a hydrophobic styrene butadiene latex with varying carboxylation and glass transition temperatures, and a hydrophilic component like polyvinyl alcohol, along with fillers like kaolin clay, which adjusts water vapor permeability based on relative humidity, ensuring stability and performance on diverse substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If petroleum-based film or facing materials are used to provide desired physical properties, then the coating can be applied to building materials, but substantial off-gassing of volatile organic compounds (VOCs) occurs during preparation and use
Solution Approach 1:
The patent changes the chemical composition parameters by using water-based acrylic polymer乳液 instead of petroleum-based materials, and by controlling the carboxylation content (0.1-10 mmol/g) and glass transition temperature (-50 to 0°C) of the polymer to achieve both manufacturability and low VOC emissions
Solution Approach 2:
The patent creates a composite coating system combining hydrophobic acrylic polymer matrix with hydrophilic filler particles (kaolin, talc, or calcium carbonate) at specific ratios (30-70 wt% filler), which provides both ease of manufacture and environmental benefits by eliminating petroleum-based materials
2Reliability
If conventional coating formulations are used, then the coating can provide some water vapor permeance, but the permeance cannot be maintained at low relative humidity levels
Solution Approach 1:
The patent utilizes parameter changes in the coating's physical state by controlling the glass transition temperature of the acrylic polymer and the carboxylation content, which enables the coating to transition between hydrophobic and hydrophilic states in response to relative humidity changes, maintaining permeance across different humidity conditions
Solution Approach 2:
The patent creates a dynamic coating system where the water vapor permeance is not fixed but adapts automatically to changing humidity levels through the hydrophilic-hydrophobic transition mechanism, with the coating becoming more permeable at low RH and less permeable at high RH
3Ease of manufacture
If current coating formulations are used, then the coating can be applied to non-porous substrates, but the coating cannot be used with porous substrates such as porous nonwovens
Solution Approach 1:
The patent develops a universal coating formulation based on water-based acrylic polymer with controlled carboxylation and Tg parameters that can be effectively applied to multiple substrate types including both non-porous and porous substrates like nonwovens, achieving broad substrate compatibility through optimized polymer-filler composition
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 coating composition achieves variable water vapor permeability as a function of humidity, providing enhanced performance on porous substrates with improved nail tear resistance, tensile strength, and UV stability, while reducing VOC emissions and maintaining desired permeance ratings across different humidity levels.
Implementation Method 1
A coating composition combining a hydrophobic styrene butadiene latex with varying carboxylation and glass transition temperatures, and a hydrophilic component like polyvinyl alcohol, along with fillers like kaolin clay, which adjusts water vapor permeability based on relative humidity
Implementation Method 2
The coating composition achieves variable water vapor permeability as a function of humidity
Data Source
Figure 1~3
AI summary
Embodiments of the present disclosure are directed to coating compositions, coated articles, and methods in which the coated article is adapted to exhibit a particular permeance profile, such as, for example, a variable water vapor perm rating of about 1 perm or less at 25% average RH and about 15 perms or more at 95% average relative humidity, as tested by ASTM E96 at 21 C.