Permeable Glass Mat Porosity Control via Pre-wetting
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Solution Overview
Problem
Existing coating processes for glass mats fail to provide close control over porosity, particularly with heavy solid coatings, which is crucial for allowing water vapor escape during gypsum curing, leading to issues with facer stability and moisture retention.
Innovation Solution
A process involving pre-wetting the glass mat by touching its bottom side with a binder slurry followed by immersion to fully saturate it, allowing control of porosity through adjustments in slurry solid content, foam introduction, defoamer addition, and blade pressure to remove excess slurry, enabling precise porosity control from fully sealed to highly open.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a heavy solid coating mix is applied to the glass mat, then the protective coating properties are improved, but the porosity control is lost and water vapor escape is blocked
Solution Approach 1:
The glass mat is pre-wetted with water or slurry before applying the heavy solid coating mix. This preliminary wetting action prepares the mat to better absorb and retain the coating materials during subsequent immersion, ensuring adequate porosity control even with heavy coating loads.
Solution Approach 2:
The patent changes the physical state and composition parameters of the coating application process by introducing a liquid slurry phase before the solid coating mix. The slurry acts as a carrier medium that modifies how the solid coating particles are distributed and retained in the mat, enabling porosity control despite high solid content.
2Strength
If the glass mat is fully sealed with coating, then the protective properties are enhanced, but water vapor escape during gypsum curing is prevented
Solution Approach 1:
The coating application creates local variations in porosity and coating density within the glass mat. The pre-wetting and immersion process ensures that coating is distributed non-uniformly, with some regions maintaining higher porosity for vapor escape while other regions provide protective sealing, achieving both functions simultaneously.
3Ease of manufacture
If conventional coating methods are used, then the coating application is simple, but the porosity cannot be closely controlled
Solution Approach 1:
The coating process is segmented into distinct sequential steps: pre-wetting with water or slurry, followed by immersion in heavy solid coating mix, then drying and curing. This segmentation allows each step to be optimized independently, maintaining operational simplicity while achieving precise porosity control through the cumulative effect of controlled material uptake at each stage.
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
This process results in a consistently porous glass mat with improved tensile strength and reduced scrap rates, suitable for use as a gypsum board facer, allowing effective water vapor escape while maintaining protective coating properties.
Implementation Method 1
passing the non-woven mat over the surface of a binder or costing slurry to touch the bottom side of the mat sufficiently to fully wet the glass mat. After the welting step, the mat is then immersed in the slurry to fully saturate the mat with the slurry material
Implementation Method 2
the binded web is dried and heated further to cure the urea formaldehyde resin or other resin binder
Data Source
AI summary
Provided is a coated nonwoven mat prepared by the process of passing a nonwoven mat over the surface of a binder or coating slurry to touch the bottom side of the mat sufficiently to fully wet the glass mat. The wetted nonwoven mat is then immersed in a slurry of the binder or coating material to fully saturate the mat with the slurry material. The process of the present invention allows one to control the porosity of the saturated fibrous nonwoven mat at high consistency with reduced scrap rate. The saturated mat will have improved tensile strength.