Battenfeld Gloucester: One of World’s Largest Blown Film Lines for Geomembranes

One of the largest blown film lines in the world has been built and installed by extrusion specialist Battenfeld Gloucester Engineering Co., Inc. The line is used to pro-duce three-layer coextruded geomembrane by a company in Latin America. High-lights include a 2,200 mm (78 inches) die weighing 40,000 kgs (88,000 lbs.) and a 25 meters (82-ft.) tower. The line produces 7,000 mm. wide (23 ft.) film in thicknesses of 500 to 2,500 microns (0.02 to 0.10 inches), at rates of more than 1,200 kg. (2,640 lb.) per hour.
Uses for the geomembrane, which are extruded of medium density and linear low-density polyethylene, include artificial ponds, landfill linings and caps, mining pollu-tion control liners, says Jorge G. Goldschmied, director of Latin American sales at Battenfeld Gloucester.

The design and construction of the blown film line posed numerous challenges. The die, one of the largest built by Battenfeld Gloucester, was engineered specifically for geomembrane, according to Goldschmied. The machining and assembly of the three-layer die was complex. Its channels optimize melt flow, eliminate dead spots and prevent overheating of the resin. Resin integrity is critical for film as wide and thick as that produced on the line. Since LLDPE was specified to increase the elas-ticity of the web, maintaining its properties as it leaves the die is vital.
The three extruders in the line are Battenfeld’s Contracool models, air-cooled units that are engineered for durability and low operating costs. The B extruder, used for the core of the web, has an 8 in. diameter (203 mm), 36:1 L/D screw. The A and C extruders, used for the inner and outer skins of the geomembrane, have screws that are 3.5 inches (89 mm) in diameter and 36 L/D. The relatively long screws increase the mixing efficiency and homogeneity of the melt and reduce process heat.
Because both skins in the multilayer web need texturing for greater traction when they are installed, Battenfeld Gloucester engineered a system that pumps nitrogen into the A and C extruders. Goldschmied says that when the nitrogen exits the die in the outer and inner layers, it disrupts the flow of resin and creates a controlled textur-ing of the skins. The line has included the ability to produce film with non-textured, extremely smooth edges. Goldschmied says this assures that the geomembrane can be easily welded to each other.
Process control is critical in a line this size. Battenfeld achieves this with its Extrol 6016 microprocessor with touchscreen control. The control in fact regulates process parameters so accurately that there is no thickness gauge on the line.
Other special components include the unfolder, secondary nip and winder, which incorporate the latest technologies and designs based on Battenfeld’s broad experi-ence in all aspects of blown film processing. The Model 196C winder, for example, is engineered for geomembrane. It features a 7.31 meter wide (24 feet) spindle and can be programmed to operate at speeds of 1 to 10 meter (3.3 to 33 feet) per min-ute. The largest roll that can be wound is 900 mm (35.4 in.) in diameter, though Goldschmied says the company generally winds rolls 400 to 500 mm (15.7 to 19.7 in.) in diameter.
Blown film is, of course, the process of choice for geomembrane, with about 80% of products extruded this way. Goldschmied says the ability of this Latin American company to produce geomembrane of consistent quality on such a large and spe-cialized line, demonstrates the engineering and manufacturing capabilities that Bat-tenfeld Gloucester provides.

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