Nonwoven Wet-laid Processing, Glass Mat Forming

November 11

Nonwoven Wet-laid Processing: Chemical Approaches

Martin Hubbe; North Carolina State University (Professor and Buckman Distinguished Scientist)

Wet-laid processing provides an effective way to prepare thin fiberglass mats with good uniformity and high production speeds.  However, success requires that the chemical aspects of processing be implemented carefully.  This tutorial overview will emphasize the importance of fiber quality, mechanical aspects, and aqueous chemistry.  Effective dispersion of fibers involves wetting, colloidal stability, and issues related to fiber entanglements.  Foam issues and hydrodynamic shear need to be considered.  Additives such as dispersants and thickeners need to be optimized, along with the procedural aspects.

Glass Mat Forming: Fiber Orientation MD/CD Tensile Ratio – Adjustments and Operation

Egon Friesenhahn; Voith SE & Co. KG (Product Manager Process Technology)

The MD/CD tensile strength ratio of glass fiber mats is an important mat property. Depending on the end use of the mat, the MD/CD tensile strength needs to be adjusted to reach the desired properties for further processing of the fiber glass mat.

Glass fiber mats for roofing shingles need a preferred strength in machine direction resulting in a high MD/CD ratio. This is to ensure process stability when impregnating the glass mat with asphalt. Other glass fiber mats used for flooring or ceiling applications may need a more isotropic fiber orientation resulting in a lower MD/CD tensile strength ratio. 

Chemicals in the white water and the binder type impacts the maximum tear force. The fiber orientation is more related to headbox adjustments but also open draws in the wet end at the transfer positions are of influence and thus on the MD/CD ratio.

The presentation shows the main adjustments that impact the fiber orientation during the wet laying process. A trial result will show the impact of the adjustments on the MD/CD tensile ratio.