This article originally ran in the June 2013 issue of Food Manufacturing.
Like many industries, the bottling industry has been trying to reduce its overall impact on the environment and develop more sustainable practices. While maintaining a greener profile can be particularly challenging, companies have definitely gotten the message from customers that they want bottling to use less material and less energy. Leading the pack is the bottled water industry, with the carbonated market close on its heels.
Using less material in the typical PET bottle has definitely had a positive impact on sustainability. The strategy, called lightweighting, reduces bottle weight as much as possible. For example, many water bottles used to use about 18 grams of plastic, and now use about 12 grams.
Decreasing the bottle’s average weight by one-third has, however, had a ripple effect on downstream operations, especially bottle packaging. Virtually all packaging machines — tray packers and loaders, case packers, shrink wrappers, and bottle packers — move bottles along a conveyor belt at a relatively high speed. To collect and organize them for packaging, the speed of the machine has to be decreased, which creates a condition called line pressure. As each bottle pushes against an adjacent bottle, it becomes pressurized, which either damages the bottle’s shape or causes processing problems as the bottles become distorted, more difficult to divide into lanes, and harder to handle and meter.
The industry has dealt with the line pressure phenomenon for quite a while, but it has been exacerbated by the advent of the lighter weight bottles, which are far less tolerant of this pressure. Since necessity is still the mother of invention, several technologies have come on the market to combat the line pressure problem. For example, Standard-Knapp offers a feature called Zero-Gap II Infeed technology for continuous low pressure product conveying. The technology eliminates the line pressure at the beginning of a packing machine and allows the packaging machinery to do a better job of handling the bottles.
Lightweighting can present problems with other large lightweight polyethylene bottles containing such products as laundry detergent, fruit juice or milk. Those bottles are generally dropped into a corrugated case by a casepacker. Sometimes, however, when the bottles land in the case and suddenly stop, significant hydraulic pressure is created by the liquid. That shock can either “pop” the cap off the container or actually split the seam in the bottom of the newer lightweight bottles.
Again, technology has been developed to handle the bottle more gently so less material can be used to make the bottle. For example, Standard-Knapp offers a feature called “Soft Catch,” which reduces the shock energy by 80 percent over a conventional drop packer. This enables the use of thinner gauge bottles and thinner glass.
Another aspect of the push towards sustainability is the use of less corrugated material in the shrink-wrapped trays that hold the bottled product. One way of doing this is with the use of U-board, which effectively eliminates the end walls of the tray, thus using less material while offering more support than a pad. The recyclability and reusability of the U-board makes it extremely environmentally friendly. What’s more, in a conventional tray, the four sides are glued together with hot melt glue, yet another area of energy consumption. Since the U-board doesn’t use glue, energy — and the glue itself — is saved during the production process.
Shrink wrapping is an area of packing that traditionally has proven to be one of the greatest drains on energy usage and a target of attempts to lower energy consumption. The metal chain pulling the cases goes into the tunnel at about 200 degrees and comes out of the tunnel at 260 degrees, which means that it is heating up the room on the return path. This is the single largest energy user in a heat train tunnel. By replacing the metal chain circulating through the heat tunnel with a plastic conveyor belt, Standard-Knapp already has significantly lowering energy consumption.
The new strategies of improving the environmental profile of bottles have had an impact on packaging, and now new technology is coming on the market that facilitates the move towards sustainability.