A study conducted by Topas Advanced Polymers (Florence, KY) revealed that discrete layers of cyclic olefin copolymer (COC) provide significant performance enhancements in three- and five-layer packaging film structures made of linear low-density polyethylene (LLDPE).
Using design of experiment (DOE) methods, Topas researchers demonstrated that COC provides greater than expected toughness, strength, stiffness and appearance in multi-layer packaging structures made of LLDPE. “We found that by splitting COC into at least two layers in five-layer structures, further significant property enhancements are possible without changing COC content,” explained Paul Tatarka, Market Development Manager for Topas Advanced Polymers at this year’s ANTEC.
The Topas team studied glass transition temperature, COC modification and blow-up ratio to quantify how COC influences the performance of several key blown film properties in three-layer (90-micron thick) and five-layer (152-micron thick) structures. The scientists found that the addition of one or more discrete layers of amorphous COC to LLDPE-based blown film significantly reduced total haze, including its internal and especially surface-haze components. It also more than doubled secant modulus, a stiffness measure.
Addition of at least one discrete layer of amorphous COC modestly improved impact resistance. Films made with 65°C Tg COC modified with Topas E-140 have impact resistance nearly 20% greater than the LLDPE control film and close to the average for heavier gauge LDPE/LLDPE generic film. Tear resistance was also significantly reduced, while tensile properties were substantially improved. Splitting COC into two layers reduced loss in PE tensile strength, elongation and impact resistance. Splitting COC into more than two layers will reduce this loss further, enabling efficient use of COC for all packaging film applications.
Cyclic olefin copolymers have become a highly valuable component in numerous packaging applications globally. These include soft shrink, sustainability-promoting trans-directional and multi-directional shrink labels, easy-tear pouches, flexible and rigid thermoformed trays, twist wrap, protective packaging and heat-seal and barrier films, said Topas.