Meaning
Internal lubricants added to polymer resins reduce the coefficient of friction on the surface of finished parts. These organic siloxane slip agents migrate to the surface after extrusion to create a thin layer that allows the material to slide easily against itself or metal machinery. They are preferred over inorganic alternatives when high optical clarity and low haze are required for packaging films.
Surface Modification
Concentration of the additive in the melt determines the final lubricity of the part. Because organic siloxane slip agents are incompatible with the bulk polymer, they are pushed outward during the cooling and solidification phases. This creates a surface that feels smoother and resists scratches during handling.
Migration Rate
Time required for the lubricant to reach the surface depends on the temperature and the crystallinity of the resin. High density polymers may slow down the movement of organic siloxane slip agents which delays the development of the slip properties. Moulders must account for this lag time when testing the friction levels of a fresh batch of parts.
Elevated storage temperatures can accelerate the process, bringing the material to its target coefficient of friction more quickly.
Friction Control
Consistent application of these chemicals prevents issues like sticking in the mould or jamming in automated packaging lines. Using organic siloxane slip agents ensures that the parts can be stacked and de-nested without excessive force. The effectiveness of the agent is measured by the static and kinetic coefficients of friction on the finished surface.
