Chasing the CAT Out: Alternative Cigarette Filter Materials

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Cellulose acetate tow (CAT) has been around for decades despite its notoriously bad biodegradability properties. But environmentally friendly filter materials are forcefully pushing onto the scene and just might give CAT a serious run for its money in the near future.

By Thomas Schmid

Cellulose acetate tow – or CAT - is today the most commonly used raw material for manufacturing cigarette filter plugs. Or rather, it’s always been, maintaining a quasi-monopoly status. That status may be justified, though. After all, CAT imparts exceptional filtering and retention properties. But, it also decomposes notoriously slowly. Additionally, during the making of filter rods the individual fibers need to be bonded together with a synthetic glue or resin, most commonly triacetine, and that doesn’t really help improve biodegradability either.

Global Problems with CAT Litter

The littering of CAT filters is, of course, a problem that contributes to environmental pollution. Each year up to 120 billion butts are carelessly thrown away on streets and sidewalks or end up in gutters, forests, parks, lakes, and rivers, in the oceans, on beaches, and where not. According to an audit conducted by the San Francisco city council some years ago, cleaning up this mess costs the municipality (and thus the taxpayer) more than US$7 million annually. And, despite being produced from cellulose fibers, the material has been chemically altered to form a polymer that stubbornly resists natural decomposition. Various studies over the decades have established that CAT filters can take anywhere from two to ten years to biodegrade. Bacteria and other microorganisms simply find it too hard to digest.

Real Alternatives Have Been Elusive

Cigarette companies have of course always scouted for alternative filter materials as replacements for CAT, but with little success. There just appears to be nothing that can match all the tried and tested advantages that CAT offers, including taste neutrality, low thermo-conductivity, high heat resistance, ease of processing and, last but not least, cost efficiency. So, CAT is here to stay for the foreseeable future. Or is it? There are in fact a number of materials that could play a significant role in eventually delegating CAT to the annals of history – if their respective inventors or suppliers play it right.

Airlaying: A Step in the Right Direction, But…

German company McAirlaids Vliesstoffe GmbH is a major supplier of a broad range of tows, non-woven fabrics and other fibrous materials used in a vast variety of applications. One particular manufacturing technique the company deploys is known as “airlaying,” which by the way is of course wittily reflected in its very name, McAirlaids. “Pure cellulose fibers are laid down in a process that is analogous to papermaking. But instead of using water to deposit the fibers, we use [pressured] air,” explains associate sales director Katja Selle. However, after airlaying the fibers normally still need to be treated with certain glues to ensure bonding and cohesion… and out the window flies much-touted environmental friendliness.

Doing Away with Glues and Resins

But in the late 1990s, McAirlaids invented a patented process that allowed the airlaid cellulose fibers to bond without such glues or resins. This resulted in a highly pure yet durable material that could be used in the rather picky food, hygiene, and medical industries, for example, to make meat pads, wound dressings and female hygiene products, just to name a few. Since the product almost exclusively consists of untreated, unadulterated, entirely natural cellulose fibers, it also biodegrades very quickly. “We are talking weeks rather than years,” asserts Selle. What’s more, it also is odorless, taste-neutral and heat resistant. Perfect for a cigarette filter, right?

Keeping a Low Profile until the Time is Right

And that is exactly what McAirlaids thought, too. Following extensive further research and development, the company about one year ago finally derived a commercially viable version of its patented material that can indeed be used as a CAT substitute, according to McAirlaids sales director, Peter Gawley. Until most recently the company preferred to stay under the radar with its product, though, “simply because it wasn’t ready for a large-scale public launch.” “Optimizing it for the cigarette filter business has only taken place over the last couple of years and we didn’t really concentrate on branding and extensive marketing,” Gawley explains.

GENIAlity on the Immediate Horizon

But that is going to change as McAirlaids intends to introduce its product officially as soon as trademarking procedures have concluded. “We are almost ready to launch the dedicated branding of our biodegradable filter, which will be called ‘Genia’. It’s a word derived from Greek and means ‘generation’,” confides Selle. “We see ‘Genia’ as the next generation filter and will market it as such.” Gawley adds that “conventional airlaid cellulose has already been in use for many years in cigarette filters in Japan, but keep in mind that they are always treated with synthetic glues as the bonding agent. We realized that airlaid cellulose with no glues or binders could have a wider application across the industry because of the increasing emphasis on the environment.”

Tests Confirm Exceptional Filtering Properties

Selle reiterates that unlike CAT, the material will fully biodegrade and turn into compost in a matter of weeks, which the company has already certified several years ago in lab tests. “And while other alternatives like paper filters, for example, are also biodegradable, ‘Genia’ creates no objectionable taste during smoking, which makes it unique.”

Furthermore, the pressure drop can be easily adjusted and – when measured at the same pressure drop point – Genia has shown to be more efficient than CAT at removing tar and nicotine, as well as being selective to phenols, findings that likewise were confirmed during the aforementioned tests. “And as we speak we are conducting yet another round of lab studies, but this time for biodegradability of ‘Genia’ when in an actual filter format,” adds Selle. “To be frank, we don’t expect any different results than from the initial study on the material. The current testing round will only reconfirm ‘Genia’s’ superiority over conventional CAT even more clearly”.

High Time for a Change

Gawley, meanwhile, is adamant that the industry needs a little shake-up, as it has become too static and, well, “CAT-centric”. “The filter material industry has not really changed in the past 50 years, so this is a great opportunity [for them] to replace existing products with something more sustainable,” he says. With interested parties apparently already on board (Gawley: “It’s still under confidentiality wraps.”), commercial cigarettes exclusively using the Genia filter are scheduled to make their debut in the European market by mid-2018 and towards the end of the year also in parts of Asia.

PLA: Similar to CAT? Not Quite.

Another alternative filter material that has made some headlines in the trade press is polylactic acid (PLA). A polymer not all too dissimilar from cellulose acetate, it is produced through fermentation and subsequent esterification of vegetable starch (normally from maize or sugar beets). First synthesized in the 1930s, it has primarily been used for producing thin laminate films, varnishes or, more recently, biodegradable plastic bags, plant pots, and similar items. But it’s only been a few years since the idea of using PLA tow for cigarette filters first emerged, with a handful of Chinese companies currently being the principal suppliers. One of them is Tianjin Glory Tang Fiber Technology Co. Ltd., a name that for obvious reasons we shall shorten to Glory Tang in this article.

Dealing in all sorts of industrial fibers, Glory Tang started manufacturing PLA tow in 2009. “Our motivation for offering the material to filter manufacturers was its proven 100-percent biodegradability and thus eco-friendliness,” says sales director Joseph Tang. “But we also saw export potential because the demand for acetate tow quite frequently exceeds supply.” The company generally uses corn as the raw material to synthesize PLA in its own factory, but Tang prefers to keep the exact process a secret.

Quick and Complete Decomposition – But at a Price

While PLA indeed very easily and quickly decomposes in pretty much any environmental condition within a few short weeks, its usage for cigarette filters has not really materialized on a large scale. Even Tang admits that his company in 2017 exported less than five tons (5,000 kgs) of filter-grade PLA tow. The calculation is simple: An average filter plug weighs approximately 0.4 grams. Considering that some loss occurs during manufacturing, 5,000 kilograms would just be enough to produce between 12 and 13 million standard-size whitesticks. That figure, of course, fades into oblivion when compared to the estimated 5.5 trillion cigarettes that were produced worldwide last year. “But our exports are nevertheless slowly increasing every year. I attribute that to tobacco companies’ rising environmental awareness and their willingness to try out PLA as a CAT substitute,” claims Tang. “Change takes time.”

Yet we suspect the true reason for the sluggish sales might be more straightforward: PLA tow is at least twice as costly as CAT, making it an expensive proposition in an industry where economic considerations are of extreme importance. But that doesn’t deter Tang to keep pushing his product. “As order quantities increase, the price of PLA tow will eventually drop as we switch to mass production,” he ascertains. “As a pioneer of PLA products, we also have our own raw material sources, which additionally will help us to come down with the price.”

A Man’s Flash of Genius

It is not always big corporations with their almost inexhaustible r&d budgets that move the world forward. Occasionally it is relatively obscure private individuals that simply observe their surroundings, leading them to have a flash of genius. With regards to cigarette filters that gifted person might just be Thuan Lu, a naturalized US citizen of Chinese descent, who resides in the small town of Centennial, Colorado. He is convinced that the product he invented and painstakingly developed from scratch could potentially revolutionize the tobacco industry.

“I am a smoker and routinely discard my finished cigarette butts in the backyard. As I collected them one day, I was pretty shocked at how many had accumulated. And I am just one single person in a sea of smokers worldwide! I also wondered why the filter butts didn’t seem to decompose even after months laying out in the open,” he recounts. Naturally curious, he conducted some online research on what conventional filters are made of and why they just wouldn’t degrade. “I recognized a serious environmental problem and decided to solve it,” he says.

Hey Jute!

What Thuan wanted was a fully biodegradable, organic filter, so he went into inventor mode. He looked at many potential natural materials, assembling them into filter plugs in his little workshop to determine what worked and what didn’t. “As you can imagine, a lot of self-experimenting was involved,” he smirks, “but I even got my friends to try out my various home-made filters.” Eventually, he whittled down his raw material choice to jute, a sub-tropical plant widely grown for its strong fibers that are commonly made into burlap sacks and other sturdy fabrics. Of course, the hard jute fibers were unsuitable for filter making if left untreated. So the inventor kept laboring and in time had developed a closely guarded method that allowed him to produce fibers many times thinner than a human hair. “I cannot tell you the exact process, but I basically decompress, dry and then purify the fibers,” he says, adding that their exceptionally low thermo-conductivity is extremely important, “because you don’t want to burn your lips when smoking a cigarette”.

Dispersal in a Matter of Hours

Thuan claims that his experiments have shown his ‘biofilters’ (as he aptly calls them) to be highly absorbent and that they “have better filtering properties than conventional [acetate] filter plugs” and “even trap some tar, too”. Meanwhile, draw strength can be easily controlled by adjusting the fibers’ compression within the plug.

“That way I can even produce light cigarettes. And as per the biodegradability, no bonding resins at all are used and the fibers are solely held together by a paper plug wrap.“ When discarded, the special plug design causes the filter to snap in half so that environmental moisture can get to work and speedily break up the fibers literally in a matter of hours, Thuan Lu claims. They then disperse with the wind or water current and turn into compost.

Patent Application and the Quest to Attract Investors

Thuan has filed a patent in the US, which he expects to be granted by October 2018. Convinced that his invention is ready for commercial production, he has recently formed his own company, BioFil Inc., which has been approved by the US Securities and Exchange Commission.

It is his hope that having a company presence will help him to attract the interest of investors and possible partners more easily. It might not be a walk in the park, though. Thuan Lu readily discloses that a couple of large tobacco companies have already rebuffed him after he demonstrated his filter invention to them. “They told me they wanted to first see some consumer tests.

With all due respect, I just don’t have the financial means to embark on nationwide consumer testing.” But he is not giving up. Many governments, he points out, are looking for ways to reduce worsening environmental pollution. Carelessly dumped CAT filters are certainly part of the problem. And who knows, the ingenious invention of an unassuming, soft-spoken man in a small Colorado town might just be the solution.