Amcor Flexibles has filed a patent for a multilayer film for lidding or flow pack applications.
The peelable film can be sealed on to polyester-based surfaces, such as sealant surfaces of polyethylene terephthalate glycol-modified (PETG) or amorphous polyethylene terephthalate (APET) thermoformed trays or on itself in flow pack applications.
The peelability is obtained by breaking the rupturable layer, then propagating the rupture between the adhesive layer and the rupturable layer.
A second breaking of the rupturable layer is needed to separate the lidding from the tray.
Inventors Tony Malfait, Anna Perez Moreno and Galina Ourieva said the film could be sealed on a polyester-based substrate, comprising a coextruded multilayer structure consisting of:
- a rupturable polyester-based sealant layer;
- an adhesive layer in contact with said rupturable layer, comprising a polymer selected from the group consisting of ionomers, maleic anhydride grafted polyolefin, EVA, EBA, EMA and EAA;
- a gas-barrier layer in contact with the adhesive layer of a gas-barrier polymer selected from the group consisting of EVOH and polyamide.
The average peel strength between the adhesive layer and the rupturable sealant layer is lower than 15N/15mm, preferably lower than 13N/15mm as measured in a 180° peel geometry.
The patent was filed by Amcor Flexibles Transpac based in Belgium in June last year to the World Intellectual Property Organization (WIPO) but was only published last week.
“The goal of peelable films in flexible packaging is to provide easy opening of a pack without physical damage of the pack caused by the use of a knife, scissors or by manual tearing and breaking by the end user," said the inventors.
“High-quality peel systems nowadays provide a smooth peeling without layer split-offs, fibre lifting, bearding, zipping or peel trace disruptions during the opening of the seam.”