Stiff & Soft Paintbrush Fibers

Filaments: Combining Softness & Stiffness
Celanex® PBT, grade 2003, extends the range of stiffness, softness and other properties of solid and hollow paintbrush filaments. PBT broadens the processing window at Specialty Filaments Inc. as much as 25 percent versus other PBTs when used in blends with polyethylene terephthalate (PET) to create filaments for semiprofessional and commodity paintbrushes. In producing its filaments, the manufacturer extrudes fibers and passes them through a water bath quench. They are then oriented at draw ratios of 3:1 to 4:1 in a hot air oven to strengthen the polymer chains and annealed in second oven to set the new polymer structure.

Broad Processability, Expanded Product Range
”We looked at many PBTs and chose Celanex® 2003 because its broader processability helps us create a greater range of fibers,” says Jim Marler, Director of Engineering and Technology at Specialty Filaments. “It expands the fiber stiffness options we offer, which translates to a more extensive line of filaments having a greater range of such key qualities as bend recovery, filament flexibility, durability and degree of finishing. It also allows for softer fibers and better tipping and flagging characteristics, so brushes can hold more paint.”

“The wider processing window also reduces waste because the extruded fiber is less likely to break during orientation. In addition, Celanex® processes more easily than other materials we evaluated. For instance, it is less brittle under normal extrusion conditions, making it easier to handle, and it eliminates ‘fiber-to-fiber’ sticking problems, which improves efficiency. Beyond this, Celanex® PBT is very consistent and helps keep our processing conditions stable.”

Better Value vs. Nylon 6/12

Picture of the Celanex® thermoplastic polyester fibers		Marler says they had evaluated nylon 6/12, which is used in professional paintbrushes, “but the cost-to-benefit ratio for polyester is far better than that of nylon 6/12. In addition, the polyester absorbs significantly less moisture than nylon and so retains excellent wet stiffness, especially when used with latex or waterbased paints.”