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New additives

How to speed up the characteristic coating time for suppressing sharkskin defects: When a fluoropolymer-based ‘Polymer Processing Additives’ (or PPA) is added to a plastic formulation that is sensitive to surface defects like sharkskin (e.g. polyethylene), it is known that these defects are not eliminated immediately.

The fluoropolymer creates a thin coating at the surface of the metal parts in the extruder (typically at the zones where high shears are like in the extruder head). This process of forming the coating takes some time. It is clear that the faster this coating is formed, the less production time is lost due to lower quality plastic film or off-spec material.

Often a fluoropolymer-based PPA exists as a combination of a synergist and a fluoropolymer (fluoroplastic or fluoroelastomer). It has been proven in earlier tests in the Dyneon laboratories that the characteristic coating time of the PPA is strongly depending of the formulation. Chemical (reactions) or physical (abrasion, adsorption) interaction can slow down the formation of the coating. Recently Dyneon developed new fluoroelastomers that have molecular properties (molecular weight – viscosity) that are able to eliminate significantly faster the surface defects (sharkskin).

Informations connexes

Reported by

3M Belgium N.V., Dyneon Specialty Additives
Haven 1005, Canadastraat 11,
2070 Zwijndrecht
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