The latest area to attract the attention of metallocene-based resins is for BOPP film. New metallocene-catalyzed isotatic PP (miPP) resins are said to offer improved processability and properties according to information from Fina (HQ: 52 rue de l'Industrie, B-1040 Brussels) and Exxon (HQ: 13507 Katy Freeway, Houston, TX 77079 / USA). Both are giving papers this month at the SPO ‘97 International Business Forum on specialty polyolefins in Houston, Texas.

According to Fina, BOPP films produced on continuous tenter equipment using miPP are stiffer and exhibit greater moisture barrier offering longer shelf-life for packaged foods and better handling on packaging lines than conventional grades. Fina believes the exceptional processability and properties of their miPP resins is related to a lower correlation of yield stress with temperature, a wider melting range and a higher molecular weight versus the iPPs.

Exxon on the the other hand, maintains that miPPs which are best for BOPP film production are those with broad and bimodal MWD and broader melting range. It achieves these through molecular tailoring and judicious control of composition distribution. As a result, Exxon has been able to demonstrate that resins with this architecture permit a substantially wider processing range than for conventional iPP resins in BOPP. Exxon's tailored metallocene resins not only provide greater processing latitude, but also the capability to operate at lower TD oven temperature. This suggests the possibility of significantly higher line speeds and of reduced energy input.

The SPO ‘97 meeting takes place from 24th-26th September in Houston, Texas. Further details from the organisers Schotland Business Research Inc (16 Duncan Lane, Skillman, NJ 08558 / USA) Tel: +1 609 466 9191 or Fax: +1 609 466 8833.