Effect of Temperature on the Slip and Blocking of Polyolefins Containing Various Fatty Acid Amides, 1999 Polymers, Laminations & Coatings Conference Proceedings

A.J. Maltby, Plastics Applications Manager, Croda Universal Ltd, Oak Road, Hull HU6 7PH, UK.

M.Read, Senior Plastics Technologist, Croda Universal Ltd, Oak Road, Hull HU6 7PH, UK.

The Coefficient of Friction of polyolefin films is normally measured at 23°C (ASTM D1894). However, this does

not always reflect the temperature of the film surface throughout the process or usage. Higher than ambient temperatures are recorded at the nip rollers in polyethylene blown film or in the stretching tunnel of biaxially orientated film units. Alternatively, low temperatures may be achieved in frozen food packaging.

Oleamide and erucamide are commonly used slip additives for polyolefins, achieving low (<0.2) coefficients="" of="" friction="" with="" moderate="" addition="" levels="" when="" tested="" at="" ambient="" temperature.="" however,="" these="" may="" not="" be="" the="" best="" slip="" additives="" to="" choose="" at="" other="" temperatures.="" this="" paper="" examines="" the="" effect="" of="" temperature="" on="" slip="" performance="" for="" a="" series="" of="" fatty="" acid="" amides="" at="" temperatures="" between="" 4="" and="" 60="" °c="" in="" ldpe.="" the="" amides="" tested="" were="" oleamide,="" erucamide,="" stearamide,="" behenamide="" and="" ethylene-bis-stearamide.="" in="" addition,="" blocking="" was="" induced="" in="" the="" films="" at="" 50="" and="" 70="" °c="" and="" the="" effect="" of="" the="" amide="" on="" blocking="" force="">

The Coefficient of Friction increased with increasing temperature until the film failed to slip at all. Saturated amides allowed some slip to occur at the highest temperatures. Unsaturated amides gave the lowest CoF values but failed at lower temperatures. At temperatures below ambient little change in CoF was observed. Blocking showed a marked difference in performance between the two test temperatures, with only behenamide and ethylene-bis-stearamide showing any improvement over the blank at 70 °C