A New Beta Nucleant Master-batch For Use in Producing Opaque Oriented Polypropylene Film and Other Unique Polypropylene Products

摘要

We have developed a beta nucleant masterbatch that can be added to a non-nucleated polypropylene resin to produce certain unique oriented film products, as well as enhance the properties and processability of molded and extruded polypropylene products When PP resins containing this masterbatch are extruded under the proper conditions, the resulting sheets contain very high levels of beta form crystallinity. When these sheets are subsequently stretched to produce either monoaxial (MOPP) or biaxial (BOPP) polypropylene film, the beta crystals transform into alpha crystals and develop microvoids.. These microvoids scatter light resulting in an opaque film, and also reduce the density of the final film Under certain circumstances it is possible to produce a microvoided film that has very high moisture vapor transmission rates, so that the film is "breathable" while also being waterproof. For thermoforming applications it has been shown that a beta crystalline PP sheet has a broader processing window than that of a conventional PP sheet, as well as exhibiting faster cycle times and improved physical properties in the final thermoformed part When the beta nucleant masterbatch is added during injection molded the final molded PP part has significantly improved impact strength at room temperature, without sacrificing its stiffness characteristics.