Harrel, Incorporated , is now offering a family of turnkey plastic extrusion lines designed especially for use with the new metallocene-catalyzed polymers such as Dow/Dupont Engage (R). These polymers are the first ones on the market which show real promise for replacing PVC (polyvinyl chloride) in tubing extrusion.
The Environmental Protection Agencies in a number of states and communities in the U.S. have expressed a desire to do away with PVC wherever possible. Counterpart regulatory bodies in other countries -- Germany and Scandanavia in particular -- have done likewise. Up until now, however, there has been no cost effective, viable alternative. Dow/Dupont's Engage not only is cost competitive with PVC but also has similar flexibility and other properties. The metallocenes also have the enormous advantage to the processor that they degrade far, far less readily than PVC and therefore are much easier to process.
There are, however, special characteristics of the metallocene materials, and, while they can be processed on regular extrusion equipment, the extrusion performance can be greatly improved by modifying both extruders and downstream equipment to handle them more readily. These turnkey extrusion lines are optimized from the hopper to the final conveyor to handle metallocenes. Appropriate changes have been made in the screws, the die, and most particularly, in the downstream equipment.
At the same time, all of the automation and the closed loop control of final tubing dimensions and characteristics have been retained. The patented Harrel TUBETROL (R) process controls both the outside diameter and the inside diameter of both the large and small sections of bump tubing, or of all three sections of double bump tubing.
And with suitable modifications to the new Alternate Polymer Tubetrol system of Harrel's, metallocene resins can be used as one of the components in a tube whose polymer composition is changed as a function of length along the tube.
Harrel tubing lines range from 3/4 inch and 1 inch, making microbore tubing for medical applications, all the way up to 2-1/2 inch and 3-1/2 inch lines making 2 inch diameter, thin wall tubing, for cosmetic or food squeeze tubes.
Anyone interested in extrusion using the new metallocene material is invited to visit the Harrel Plastic Development Laboratory in Norwalk, CT, for a demonstration of bump tubing extrusion with metallocenes. There's nothing like actual hands-on experience to show what metallocenes can do for you in your plant!