Plastomers Find New Uses in Bottles.

DEX-Plastomers of the Netherlands, a joint venture of DSM and ExxonMobil Chemical Co., Houston, has developed two novel uses of metallocene plastomers in blow molded bottles. DEX-Plastomers makes ExxonMobil's Exact plastomers in Holland.

* One development is soft-touch squeeze bottles made by coextrusion blow molding a thin, tactile skin of plastomer over a polyethylene inner layer. The outer skin can be as little as 5% to 7% of total wall thickness, minimizing the amount of costly plastomer. Another way to hold down cost is to blend PP copolymer with plastomer for the outer tactile skin layer. Different levels of soft touch can be achieved by varying the amount of plastomer (Exact grade 8201 is recommended). By using a high-clarity PP, transparent soft-touch bottles can be produced.

* Also new are PP random-copolymer bottles that use Exact plastomer to get improved impact resistance with no loss of clarity. Such bottles have been on the market in Germany for about a year. As little as 10% plastomer can significantly boost toughness without increasing haze, unlike other impact modifiers, says DEX-Plastomers. Optimal amount and type of plastomer depend on bottle requirements such as minimum service temperature and stiffness. The plastomer reduces stiffness while it raises toughness, so a balance between those properties must be struck.