Why Didn't The Sliding Additive Work?

Additive manufacturers and plastic processors know that polymer films have a high coefficient of friction (0.5-0.6). This leads to problems when using films on packaging equipment. The film moves unevenly, heats up from friction, loses its geometry. This can lead to film breakage.

To improve the film's sliding properties, a sliding additive is introduced during its production (usually the active substances are oleamide and erucamide). After film extrusion, the additive migrates to the surface and creates a sliding layer on it, due to which the friction coefficient is significantly reduced and the film's sliding properties are improved.

It was important for the client to achieve a stable friction coefficient, since this affects the operation of the packaging equipment. Also, in the future, it was planned to apply printing to the film. These factors had to be taken into account when selecting the masterbatch and recipe.

Lack of sliding additive	Excess of sliding additive
Leads to heating and softening of the film, its stretching and breakage	•   worsens roll winding (a telescopic effect occurs) •   worsens the film's welding properties •   affects printing (reduces paint adhesion to the film surface)

Oleamide has a high migration rate and begins to act almost immediately after film extrusion (70-80% slip is achieved after 30 minutes), although maximum slip occurs after 24 hours.

The sliding effect of erucamide appears 4-6 hours after film production. Maximum sliding occurs after 72-96 hours.

When faced with the problem of determining if an additive has migrated prematurely to a surface, several areas can be checked:

• check the recipe

• clarify the parameters of the raw materials

• polymer type (the higher the density, the slower the migration)

• erucamide content in the layer

• presence of anti-blocking and chalk additives in the layer

• presence of polar polymers in adjacent layers (EVA, PA, EVOH or adhesive, which attract part of the sliding additive)

• presence of other migrating additives (antistatic, antifog), which will compete for space on the film surface.

• Check storage standards, temperature and air humidity, otherwise the additives may not work effectively

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