Glass fiber sizing for reinforced thermoplastics

Baybond® polyurethane dispersions for superior glass fiber sizings

Glass fibers provide added strength to many plastics so they can be used in place of metals in appliances, sports equipment and cars. Glass fiber sizings make it possible to add the fibers to the plastic and polyurethane (PU) resins to make some of the highest-performing reinforced composites.

Glass-fiber reinforced thermoplastics, such as polyamide 6 (PA 6) and polybutylene terephthalate (PBT), are attractive because they are lightweight and have great strength.

Glass fibers must be treated before they are used. To protect the fibers from one another and impart unique properties, glass fiber sizings are applied.

The film former is one of the main components of a glass fiber sizing formulation. It protects and lubricates the fibers and affects the way they interact with one another and the plastic matrix.

Baybond® waterborne polyurethane dispersions (PUDs) from Covestro include both polyester and polyether polyurethanes based on aliphatic and/or cycloaliphatic isocyanates that have been specifically designed for glass fiber sizings.

Ionic/non-ionic hydrophilic modification of Baybond® polyurethanes sets them apart from other currently available products and gives them a unique combination of characteristics:

  • Excellent film-forming properties, adhesion and colorfastness
  • High shear and hydrolytic resistance
  • Good pH and thermal stability
  • Good compatibility with silane bonding agents, adhesion promoters, slip agents, antistatic agents and flexibilizers

In addition, sizings formulated with Baybond® polyurethanes strengthen the bond between the plastic and the glass fibers, enhancing the mechanical properties of the reinforced thermoplastics.

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