Bringing Together the Many Benefits of Film and Paper

Published: October 01, 2000, By Michael Maddox, Contributing Editor

Flour and sugar, conventionally packed in block-bottom paper bags, are among the first targets for a coextruded polyethylene film that has been developed by new British converter Harrier Packaging.

The product, designated PaperFeel, reportedly looks, feels, prints, and converts like paper but has the advantages of a moisture barrier and resistance to oils and fats.

Based at Peterborough, Harrier Packaging was set up in August 1998 with a œ3 million investment to bring PaperFeel film to the market. Production started during the summer of 1999, when the first sales were made in the food ingredient, pet food, and animal feed industries.

"The opportunities for a film that incorporates the benefits of paper without its drawbacks are particularly large in the food industry," says Harrier's managing director, Bruce Wilson-North. "This is all about a step change in technology that allows more to be achieved with developed paper printing and converting technology but without additional cost."

Initially, Harrier is concentrating on roll-bottom sacks, block-bottom bags, and sewn-open-mouth bags for the food industry, where the company believes the advantages of moisture barrier and fat resistance are particularly valuable.

However, PaperFeel is heat-sealable and so can be run on form/fill/seal packaging machinery, while its paper-like deadfold quality also allows it to be used as a confectionery twistwrap, according to Wilson-North.

"PaperFeel has potential applications in a lot of packaging markets, as well as envelopes, for example," he says, "but we are targeting the food industry specifically, because that's where we think the shortcomings of paper are most evident."

New Equipment Runs New Product
Harrier has invested in three main items of new production equipment: a Battenfeld Gloucester three-layer blown film coextrusion line; an eight-color Schiavi central impression flexo press; and what Wilson-North says is the first US-built Weber bagmaking machine solely for PE converting.

He explains that the Battenfeld machine was specified particularly for uniform film thickness and smoothness, with the aim of matching the standards of surface finish and gauge historically achieved in paper manufacture through processes such as calendering.

"We are looking to use plastics-processing technology to match paper industry standards. If you are aiming to do everything that paper does well, reel quality has to be the same as in the paper industry, and if you are going to compete with paper on decoration quality, you have to use paper industry-standard presses," Wilson-North explains. "There is no point in using that standard of press if a reel is wavy."

The filled resins used in the production of PaperFeel are highly viscous. So, to achieve the temperature uniformity and dispersive mixing required for the finished product, the Battenfeld machine employs three 60-mm grooved feed throat extruders with the latest variable lead barrier screw technology, Wilson-North says.

He adds that a dual-lip air ring is incorporated immediately after the 200-mm, three-layer die to promote a high level of continuous cooling and stability, while for fine control over profile, the line is fitted with Battenfeld Gloucester's AutoProfile system. This controls film thickness by varying the cooling rate in localized areas, influencing the draw of the material. Heat is applied at specific locations on the air ring, using a system of finned heaters in the cooling airflow to thin out any thicker areas of the bubble, says Wilson-North.

He also talks about the eight-color, Italian-built Schiavi Sirio 228 central impression, flexographic press chosen by Harrier Packaging, noting that it has a print width of 1,200 mm and is capable of mechanical speeds to 300 mpm. It is equipped with microdot plate mounting in which, via the use of cameras at each print station, plates can be mounted to achieve color-to-color registration to within 100 microns.

The press also is fitted with what is reported to be the first DC-driven turning bar employed on this style of machine, allowing film up to 600 mm wide to be taken around the CI drum twice for reverse-side printing in a single pass.

"The benefit of the DC-driven turning bar is that it gives us accurate front-to-back registration," says Wilson-North. "Web tension control on a machine like this is very important, and the driven turning bar allows us to obtain the quality of front-to-back registration that we need."

For bagmaking, Harrier has installed a standard block-bottom paper bag machine from H.G. Weber, which Wilson-North says required minimum modification to run the new PaperFeel material. Three stainless steel rollers have been replaced with rubber-covered rolls, and while PaperFeel is heat-sealable, the conventional glued base is retained.

"One of the things the paper converting industry has done very well," notes Wilson-North, "is develop a way to make bags with predictable geometry—square bases, precise folds, and so forth—which is important for automated filling lines within the food industry. PaperFeel allows established paper industry technology to be used, keeping the best of paper converting and adding the improvements that plastics can bring. There's no need to throw out the baby with the bath water."

Supplier Information
Battenfeld Gloucester Engineering Co., Gloucester, MA; 978/281-1800; bge.battenfeld.com

Schiavi SpA (Bobst Group, Piacenza, Italy; +39 (0) 523 493 1; bobstgroup.com

H.G. Weber & Co., Kiel, WI; 920/894-2221; hgweber.com