- February 07, 2002, Teresa Koltzenburg, Senior Editor
Ozone generation: What is it and how can it benefit your extrusion lamination applications? Those are a couple of the questions PFFC recently posed to the experts at Pillar Technologies and Sherman Treaters (both part of ITW, Inc.).
Stuart Greig, sales director, Sherman Treaters U.K., and Scott Kessler, sales manager, Pillar, provided us with the answers to these ozone-generation questions and more. So if you're interested in helping out your extrusion lamination operation's bottom line while simultaneously making better product, this is one Q&A you won't want to miss.
PFFC: Can you explain ozone generation technology?
Greig: Basically, ozone generation is an additional adhesion promoter; it’s an additional method of promoting adhesion between various polymers and substrates.
The ozone generator, which produces a high concentration of ozone gas, goes along [with other treating equipment], like the corona treater and the gas-flame treater.
PFFC: When would this type of technology be used in a converting facility?
Greig: The only application for ozone generation is extrusion coating or extrusion lamination, when a molten polymer [is extruded] onto a moving substrate. Basically, it’s used in addition to the corona and the flame treaters. It’s not either or; it’s to be used in conjunction with the corona treater or the flame treater.
Typically, the corona treater will pre-treat the carrier web (or the base substrate), and the ozone is there to promote adhesion of the molten polymer as it comes out of the die. Basically, you’re getting a "treat" on the two substrates—the substrate and an extrudate—and when they come together, you’ve got a double-hit as far as adhesion levels are concerned.
PFFC: What was the impetus for ozone generation technology?
Greig: It goes back a number of years, really. Initial use of ozone generation was in aseptic packaging, where you were looking at multi-layer substrates being laminated together. One of the best examples is the fruit juice carton (or even milk cartons) where you have a paper or board substrate and then you have a polymer laminated to that. And in some cases, with aseptic, you have aluminum foil. So when you talk about a fruit juice or orange juice carton, you probably have about five to seven layers of material there to make up that one carton. The whole success of the carton is ensuring that all those layers stick together.
[For adhesion purposes], you can use different types of polymers, you can use adhesives, you can use tie-layers, and they will all give you a final result. But as productivity becomes an issue, the commercial aspect of the package becomes a big issue, the down-gauging of the thickness of the polymer layer, when those sort of parameters start to come to fruition, you can look at the addition of ozone to improve the performance of the package under better productivity conditions.
PFFC: So as things are getting…
Greig: …faster, more competitive, you want to use more conventional, less expensive polymers. Adhesive co-polymers, adhesive tie-layer polymers—these are expensive polymers for customers to use. We’re saying that you can use conventional, run-of-the-mill polymers, and forget about adding in these expensive materials. You make a one-time investment with this piece of equipment, and then you have much wider processing parameters for your extrusion lines.
PFFC: So what type of application(s) would ozone generation be suited for?
Kessler: Anywhere where a customer is extruding a layer of plastic onto a carrier web, be it foil, another layer of film, or perhaps a board or paper. The ozone generation is used to increase that bond strength.
Greig: And where the productivity level is an issue. The line speed demands are moving more and more into the high-speed direction. [In addition,] the customer is concerned about down-gauging the layers of material as well as the amount of material they’re using. These are the basic parameters for using ozone generation.
Kessler: As Stuart referred to earlier, ozone generation is not a replacement to corona or flame treating. This is another process that would be used in conjunction with corona or flame to help the customer make a better product. It’s a go-with, as opposed to replacement.
And in terms of payback, it’s not just a quantitative payback, but it’s a qualitative process improvement as well. It’s not just, "You’re gonna make this much more, using this much less plastic." But the customers can reduce the gauge of the extrusion, which means they are producing more product with less material, reducing their costs. They also can run higher speeds, which increases their productivity. And they are able to reduce their melt temperature, which helps them to run a better quality product.
PFFC: What are some of the more recent developments in your ozone generation equipment?
Greig: Most of the modern-day extrusion lines are run by PLCs or computers. With this control technology that's now available, an operator can control ozone generation by these line PLCs. So, you’ll get a lot of data from the ozone generator.
In the early days, the ozone generator was very much a stand-alone type of operation. All of that is now controlled by PLCs, so the customer has a lot more data available. He can control flow rates; he can control concentrations; he can control the width of the deckling of the ozone so he doesn’t have to fill the factory full of high concentrations of ozone. There are alarm systems all around the unit such that, in the event of ozone leakage or a failure in some of the components, the unit is going to be fail-safe. It’s not going to be left to run ozone into the building. So, basically, making the unit more operator-friendly; that's the ultimate answer to the question.
PFFC: What are converters asking from their ozone generation equipment investment?
Greig: Basically, they’re looking for repeatability. They want the unit to be programmable, so that when they’re running the same job again, they know the ozone generation will reset to conditions we had last week, last month, etc, automatically, and will not be dependent on ambient conditions, power-supply changes and fluctuations, or anything along those lines. Repeatability is really what they’re looking for.
PFFC: What physical modifications (of the facility) would a converter encounter if he or she decides to integrate this type of treating system into an operation's process(es)?
Greig: The integration of a ozone generation into an extrusion coating line actually is very simple. Because our ozone generators are water-cooled to maintain their integrity, some basic piping [as well as some other stainless-steel piping] is required. Then the integration of actually getting the ozone onto the line is very simple. Yes, there is some technical input that we need from the converter, but we will design the suitable brackets to hold the ozone equipment onto the line. The integration is very simple, very straightforward.
PFFC: Future direction: Where is Sherman taking this technology in terms of innovation?
Greig: I think we’re slowly opening converters' eyes to the possibility of using ozone. We have several lab-style set ups where we can test the suitability on certain polymers. We certainly know several converters that have switched from using an expensive polymer, and with the introduction of ozone, they’ve been able to run something that’s a lot more cost-effective for them. And also, as more and more converters get into barrier-layer type films—which have to be extruded at very low melt temperatures—ozone is certainly the answer to their problems as far as adhesion is concerned.