Developments in Aerosol Technology

I collected a selection of developments in Aerosol Technology, introduced into the market over the last six months. Aerosol Technology is a very interesting technology with a wide and amazing range of possibilities and applications. For a long time it has been seen as a “not-moving-forward” packaging format and it even met (and sometimes still meets) strong opposition and rejection due to its history of air-pollution and negative effects on the environment. Before we go into the new developments, let’s have a look at its history, the negative aspects and the oppositional claims.

For the ones not intimate with aerosol technology a short definition:
An aerosol is a dispenser that holds a substance under pressure and that can release it as a fine spray (usually by means of a propellant gas). This is obtained with a can that contains a liquid under pressure. When the spray valve is opened, the liquid is forced out of a small hole and emerges as an aerosol or mist. As gas expands to drive out the payload, only some propellant evaporates inside the can to maintain an even pressure. Outside the can, the droplets of propellant evaporate rapidly, leaving the payload suspended as very fine particles or droplets.
Note: An atomizer or spray pump is a similar device that is pressurised by a hand-operated pump rather than by stored gas. About this system, which is the forerunner of the airless system, to be discussed later in this article.

A brief history
Although there is proof that a with gas pressurised container has been used some 400 years ago, it is generally agreed that the forerunner of the modern aerosol is the in November 1927 by Erik Rotheim in Norway patented aerosol can and valve that could hold and dispense products and propellant systems. During World War II the US government funded research into a portable way for service men to spray malaria-carrying bugs and in 1943 researchers of the Department of Agriculture developed a small aerosol can pressurised by a liquefied gas.

The first aerosol cans made of aluminium were produced in Germany in 1954. These were 2-piece cans based on a patent of Ernst Kohl. Their principle draw-back was the domed base which was still made of tinplate, and often led to leaks around the seam.

In 1955 the commercial advance of the aerosol can started with the introduction of the first hair spray in Germany. Various industrial branches discovered this packaging system since then leading to considerable growth figures for aerosol can manufacturers.

Environmental aspects
Chlorofluorocarbons (CFCs) were once often used as propellants, but since the Montreal Protocol came into force in 1989, they have been replaced in nearly every country due to the negative effects CFCs have on Earth’s ozone layer.

While aerosol containers no longer contain chlorofluorocarbon or CFC, these thin-walled steel or aluminium vessels are pressurized with one of several volatile hydrocarbon propellants, such as carbon dioxide, propane and butane.  These propellants are “greenhouse gases” that contribute to global warming and smog formation.
Nitrous oxide and carbon dioxide are used as propellants to deliver foodstuffs (for example, whipped cream and cooking oil).
In general it can be said that an aerosol can never is completely empty, consequently the post-consumer spray cans, however, are considered hazardous waste because they contain ignitable or chlorinated solvents or other toxins such as pesticides and phthalates.

Note: An atomizer or spray pump is a similar device that is pressurised by a hand-operated pump rather than by stored gas.

In answer to the unattractive environmental aspects of aerosols with a propellant, we have seen a notable increase in airless packaging in recent years.

Airless technology
Before airless technologies existed, brands chose atmospheric, or dip-tube pumps. When a dip-tube pump, often called atomizer or spray pump, is actuated, it creates a low-pressure area in front of the product inside the bottle near the pump intake. The atmospheric air behind the product moves toward the low pressure and pushes the product in front of it until it is dispensed by the pump.

There are two main types of airless systems, but the most used is the piston airless system. A piston airless system uses a moulded piston in the bottle, to help push the product out of its package. Airless systems by design create a vacuum. The piston helps maintain that vacuum.

Recently the pouch airless system is getting popular, capturing a significant percentage of the airless market. A pouch system is made of a rigid bottle containing a soft pouch with an airless pump. When the product is expelled, the pouch shrinks so that there is no air intake inside the pouch.

After this introduction we can have a closer look at the new developments recently introduced into the market. It is a mix of developments in airless systems and in the pouch airless system. We will see the Airless Paper Blow from Yonwoo, the Bag-On-Valves from Coster, the dual-chamber dispensing bottle from Gidea, and Eggs packaged in aerosol can.

But before we go to the specific applications, let’s have a look at the recent developments in aerosol manufacturing technology.

Stahl Monoblock aerosol can
Aerosol cans are traditionally made up of three parts. The development of new coating systems around 1960 made it possible to produce one-piece aluminium cans – the Aluminium Monobloc aerosol can. Last year Mall + Herlan GmbH in Germany developed a prototype made out of one piece tinplate. This Stahl Monoblock aerosol can features all the advantages of a monoblock aerosol can, previously only available in aluminium. The prototype represents a high technological innovation performance with this difficult moulding technology. Using tinplate, the cost factor becomes much more advantageous than with aluminium and thus increases the economic viability of aerosol production.

Recycled-content aluminium aerosol can
Currently, almost all extruded aluminium aerosol packaging is made from virgin aluminium slugs, which are impact extruded to produce packaging for aerosol products.
A metal technology breakthrough from Ball Corp. enables the use of recycled aluminium in the manufacture of extruded aluminium packaging for aerosols. The resulting new metal alloy exhibits increased strength and allows light-weighting of the container by as much as 10% without affecting package integrity.
Ball Corp. will use aluminium recycled from Ball’s global beverage can operations to produce the company’s new slugs.

A solvent-free internal powder coating from Tubex
This year Tubex received the Paris Aerosol Award for a revolutionary and ecologically friendly solution for internal coatings, an application of a solvent-free internal powder coating with the best chemical properties and high mechanical resilience.
German cosmetic manufacturer Beiersdorf AG is currently in the process of changing the production of its aerosol cans manufactured by Tubex from standard to internal powder coating.
Tubex claims to be the only aerosol can manufacturer worldwide which is able to apply internal powder coating industrially.

Tubex introduced a prototype of its “Yes Green Can” in 2010, claiming that with its optimized material input and sophisticated production technology the “Yes Green Can” embodies all characteristics of modern sustainability.
The can was produced from slugs which contain about 20% recycled clean and printed can production scrap, thus reducing the use of primary aluminium. Furthermore volatile organic compounds (VOC) emissions from the can production process could be significantly reduced by the application of a solvent-free internal powder coating and the use of a water-based base coat and over varnish.

De-bossed cans from Ardagh
The Ardagh Group created a tinplate three-piece aerosol can for the fashion designer Carolina Herrera’s range of fragrances. The aerosol can incorporates a complex de-bossing feature.

This striking embossed new feature complements the subtle colour in the decoration and a transparent cap highlights the reflective dome and matching actuator. The de-bossing feature was designed and developed specifically for this project and required the modification of the existing production lines.

In the next article I will describe some new developments in specific applications for airless and bag-on-valves aerosols.