Multimodal PP from Borouge delivers temperature resistance and balanced seal-peel properties to provide a unique venting feature for multilayer blown film intended for microwaveable food packaging.Borouge, a leading provider of innovative and value creating plastics solutions for packaging applications has entered a new market for its multimodal PP for blown film. Based on Borealis Borstar technology which allows application-specific tailoring of material properties, Borouge has supplied multimodal Borclear polypropylene (PP) and Steripeel PP to provide the performance layers in the innovative M-Vent microwaveable pouch produced by TPN FlexPak, Thailand.
The M-Vent Pouch is a new concept with an innovative sealing feature that allows it to ‘breathe out’ while its contents cook in a microwave oven. This novel selfventing attribute provides for the safe and reliable release of steam from inside the pouch without requiring partial opening or puncturing before placing in the microwave. Thereby providing the consumer with the ultimate convenience in cooking either fresh, frozen or shelf-stable foods.
According to TPN FlexPak, one of South East Asia’s leading producers of flexible printed packaging for foods, as well as other mass produced consumer items: “It was clear from the outset that in developing M-Vent Pouch we would need film with some very special property combinations. We had used Borstar bimodal polyethylene products from Borouge for blown film packaging applications for a number of years, so we first looked to these for a solution. However, the overall performance criteria for the pouch demanded a range of properties beyond the capability of a single film material.”
The primary challenges were that the food contact material offered excellent organoleptic properties, preserving food flavour and odour, and that it provided outstanding seal and peel characteristics to enable the self-venting process and giving easy opening. Also important was both high and low temperature performance, as the pouch had to be capable of accepting both hot-fill up to 100°C and frozen storage down to -20°C, as well as transition from freezer to microwave oven temperatures.
“Having previously worked with Borouge on many successful projects we drew on their materials expertise to help us in defining the structure and identifying the required materials,” says TPN FlexPak.
The solution for the M-Vent Pouch was to combine the advantages of both multimodal polyethylenes (PE) and PP in a multilayer structure. This comprises a PE outer layer laminated to a PET substrate and a Borclear PP carrier layer which delivers good heat resistance and brings robustness to the sealing process.
Key is the contribution made by Steripeel a peelable compound; this provides the seal-peel layer for balanced sealing and opening performance making it both secure and convenient. And, it is Steripeel, in conjunction with TPN FlexPak’s advanced sealing technology, which enables the unique self-venting performance of the pouch during microwave cooking.
As well as meeting the mechanical criteria, Borstar multimodal PP for this blown film application delivers a step change in purity and organoleptic performance together with excellent barrier properties that ensure the preservation of both the natural taste and aroma of the packaged food.
Moreover, multimodal Borclear and Steripeel bring the extra advantage of being easily processed on existing PE blown film lines, thereby eliminating the need for any additional investment in production equipment. This contributes to widening the possibilities for the M-Vent Pouch to be used economically for small series runs to serve markets for niche food products.
