21 October 2024

The future of aerosol: Are you aware of the possibilities CO2 could offer as a propellant?

In most of my conversations with industry experts and aerosol veterans, there seems to be little doubt that the future of the aerosol industry is heading towards CO2 or maybe to put it differently moving away from volatile liquid gasses like butane and propane. Main driver is the climate concern related to these gasses as well as the risks and regulations that come with the use. Gas houses, stringent safety requirements, the constant fear of a disaster and the vast amount of administrative work associated with working with these explosive gases. So why is not everyone making the shift now? 

As a Business Developer at Budé I ran into different groups of people. Specialists working for producers of aerosol products, contract fillers, or outsourcing companies. During these encounters I hear a lot of different arguments, such as “as a contract filler we do not get questions from our clients and therefore are reluctant to offer alternatives.” Or: “we have done it for many years and have learned to deal with the challenges, so why change?”  

Probably the most heard argument is that liquid gases have a clear performance benefit when it comes to aerosols. The liquid gas acts like a solvent, it evaporates quickly which helps create a nice spray pattern and the pressure in the can remains constant as long as there is liquid gas in the can.

It is clear that work is needed when shifting from liquid gases to CO2 as it may require formulation changes, testing and looking at valves and diffusers. The biggest problem I recognize is that a lot of people I talk to are unaware of the possibilities CO2 could offer. It allows to create aerosols that are perceived environmentally friendly, work with higher pressures, could offer cost savings as CO2 is considered a low-cost gas and appears to be the only option when liquid gasses are not suitable for various reasons.

Then there are companies who believe it is not possible to move away from liquid gases, or that have looked into CO2 in the past, were not able to make it work, and are not interested in giving it another look. However, technological developments have taken place in both gassing technologies and products like valves and diffusers. 

Luckily, there is also a group that does realize C02 has a future and is eager to test and understand the possibilities. The nice thing about CO2 is that it dissolves in liquids. So next to the gas in the headspace of the aerosol there is a significant amount of CO2 in the liquid. The higher the pressure the more CO2 dissolves which means that when an aerosol is used, and the pressure drops, gas will evaporate from the liquid and increases the pressure as a result of which the pressure drop when emptying the can, is not as steep as with a non-dissolving gas like N2. Solvability differs per product and for instance with water, the amount of CO2 doubles when dissolving gas into the water. For some solvent products like aceton, the amount increases a lot more.

Budé is using a technology called “shaking” that helps to efficiently dissolve the gas in the liquid by shaking the can while adding the gas. This technology is easier to implement than the alternative, called “impact gassing” and as such instrumental in the transition to CO2. We have performed tests with products like vegetable oils, baking sprays, insect sprays, cosmetic products or industrial products where using CO2 as a propellant created a very well performing product.

It is clear that compressed gasses have limitations and so do liquid gasses. Budé Aerosols is working with a growing group of companies to test CO2 with a diverse range of aerosol products and is doing internal tests to better understand and inspire the market to do more testing. In particular with our gassing/shaking technology which can create a lot of new product opportunities. How does testing work? Just send us some filled cans without gas and we will fill them with CO2 using our shaking technology, and return them for your evaluation as a starting point for further development.