Microporous Breathable Building Materials via Phase Separation
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Solution Overview
Problem
Existing breathable materials for construction, such as housewrap, require complex and costly manufacturing processes to achieve the necessary balance of strength, breathability, and water vapor transmission rates, often involving incremental stretching or specialized machinery.
Innovation Solution
A method involving a fabric layer coated with a microporous polymer film composition and filler, where the material undergoes minimal physical manipulation to create micropores, maintaining dimensions within 2% of the original, thereby achieving a water vapor transmission rate greater than 50 g/m²·24 hr without the need for extensive stretching or expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If strong and/or tough nonwoven and/or woven fabrics are used to provide sufficient strength and toughness, then the material can withstand the rigors of the building process, but the manufacturing process becomes more complex and expensive
Solution Approach 1:
The patent combines the fabric reinforcement function and the microporous coating function into a single integrated laminate structure. The polymer coating is applied directly to the fabric surface and simultaneously provides both structural reinforcement and breathability through micropore formation, eliminating the need for separate processing steps for each function.
Solution Approach 2:
The patent uses a microporous polymer coating applied to the fabric surface. The micropores are formed through phase separation of the polymer composition during coating application, creating a breathable membrane that allows water vapor transmission while maintaining liquid impermeability. This porous structure provides the necessary strength without requiring complex multi-layer constructions.
2Quantity of substance
If incremental stretching is used to render the polymer coating microporous, then the water vapor transmission rate increases, but the manufacturing requires specialized machinery and capital expense
Solution Approach 1:
The patent changes the physical-chemical parameters of the polymer coating by using a composition that undergoes phase separation during the coating process. By selecting polymers with specific glass transition temperatures and using appropriate solvents or water-based systems, the coating spontaneously forms micropores without requiring mechanical stretching equipment. The parameter change occurs during coating application rather than in a separate stretching step.
Solution Approach 2:
The patent replaces the mechanical stretching system with a chemical/physical phase separation process. Instead of using mechanical forces to create micropores through stretching, the invention uses the phase separation behavior of the polymer composition during coating application to spontaneously form the microporous structure. This substitution eliminates the need for incremental stretching machinery.
3Quantity of substance
If the polymer film layer is stretched to create micropores, then breathability improves, but the material dimensions change significantly from the original
Solution Approach 1:
The patent employs a microporous coating formed through phase separation that creates breathability without requiring bulk material stretching. The micropores are formed within the polymer coating layer itself during the coating process, allowing water vapor transmission while the underlying fabric layer maintains its original dimensions. The breathability is achieved through the porous structure of the coating rather than through stretching of the entire laminate.
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 breathable materials with enhanced strength, breathability, and liquid impermeability, simplifying the manufacturing process and reducing costs while maintaining desired performance characteristics.
Implementation Method 1
the polymer coating is rendered microporous by a relatively small amount of moving, twisting, calendering, or otherwise physically treating the coated woven tape fabric
Implementation Method 2
the breathable material has undergone a physical manipulation to render the polymer film layer microporous such that the WVTR of the breathable material is greater than about 50 g/m2·24 hr
Data Source
AI summary
Breathable materials comprise a fabric layer and a polymer film layer thereon, the polymer film layer comprising a polymer composition and a filler, wherein the breathable material has undergone a physical manipulation to render the polymer film layer microporous such that the WVTR of the breathable material is greater than about 50 g/m2·24 hr, and wherein the breathable material has a first length dimension and a first width dimension before said physical manipulation and a second length dimension and a second width dimension after said physical manipulation, wherein the second length dimension is no more than about 2% greater than the first length dimension and the second width dimension is no more than about 2% greater than the first width dimension. Methods of making a breathable material comprise forming a polymer film layer comprising a polymer composition and a filler; bonding the polymer film layer to a fabric layer to form a laminate; and applying a physical manipulation to the laminate to render the polymer film layer microporous such that the WVTR of the resulting breathable material is greater than about 50 g/m2·24 hr; wherein the breathable material has a first length dimension and a first width dimension before said physical manipulation and a second length dimension and a second width dimension after said physical manipulation, wherein the second length dimension is no more than about 2% greater than the first length dimension and the second width dimension is no more than about 2% greater than the first width dimension.