Rough Surface of Extruded Staioners' Rubber Bands

Manufacturer: We are manufacturing stationers' rubber bands using dry rubber extrusion process but have been experiencing undesirable surface roughness persistently. All attempts in reformulation and process changes are to no avail. Hope you can help us. We've sent you our formulations.

John Woon (Senior Latex Consultant): Thanks for sending me your formulations which helped me in my diagnosis of your problem.

You can easily overcome the problem by either switching your SMR to SP 20 or blending both.
SP means "Superior Processing Rubber" made form mixing vulcansied latex with normal latex at different ratios before the latex blend is coagulated to obtain the dry rubber. It has superior processing characteristics and good dimension stability which are ideal for calendering and extrusion processes. The extrudates would also show a smoother surface.

SP 20 indicates that 20% of the latex blend is vulcanised latex.