How can we reduce plastic within cleaning products?

What are plastics?

Plastics are large carbon-containing polymers, which are composed of repeating units of shorter monomers. Different monomers can be combined to produce a wide variety of plastics, with different properties. Most plastics are chemically inert and will not react with other substances; For example, you can store alcohol, detergent, water, acid or alkali in a plastic container without damaging the container itself. They also tend to be lightweight and very durable. This durability, however, is why a reduction in our plastic usage is necessary. Once in a landfill or the environment, it can take many years for plastics to degrade meaning they take up a lot of room and damage the surrounding wildlife. There is also the argument that even once degraded, tiny plastic particles, smaller than 5 millimetres across, called microplastics will remain. These can then be ingested by and further damage marine life but can also make their way into human diets.

Figure 1: The chemical structure of a monomer unit and the polymeric structure of Polyethylene terephthalate, otherwise known as PET or PETE. This is a common polymer found in plastic bottles.

Finding alternative materials can be difficult. One possible candidate is glass, which is chemically inert but is also heavy and fragile. There are also metallic packaging options, but these are more chemically reactive and are prone to damage during transport. There are several emerging paper solutions, but some form of plastic insert is often required in order to separate the contents from the paper. In terms of durability, it can also be difficult to store liquids in this sort of packaging.

Concentrated formulations for reduced plastic

So if plastics are difficult to replace in this industry, what other options are there?

Many ready-to-use cleaning products are > 95% water. By concentrating the formulations contained within, the requirement for plastic packaging can be significantly reduced. If you were to prepare a concentrated formulation that could be diluted down to 1% v/v in a 500 ml trigger spray bottle, you’d need 5 ml of concentrated product per refill. From a 1 L container of concentrate, you could therefore fill the same 500 ml bottle 200 times. This allows for a 100-fold reduction in plastic containers and reduces the carbon footprint by minimising the volume of products requiring transportation.

Figure 2: Plastic bottles have thus far been the most effective containers for cleaning products, but the majority of what is contained is water so concentrating the formulation for dilution by the end user could reduce the plastic needs of the HI&I sector.

Concentrated products can be in solid or liquid form. Powdered products allow for a very high active content, however, they can be significantly more difficult to process and dose when compared to their liquid counterparts. Also, many powders are highly cohesive and so do not flow well on their own and prolonged storage can lead to caking due to climatic conditions and pressure. To combat this, flow aids and anti-caking agents can be added to the formulations. These flow aids cover the surface of the host powder, creating a surface roughness that helps physically space the particles from one another. Evonik offer a wide range of fumed and precipitated silicas from their AEROSIL® and SIPERNAT® product ranges. As liquid formulations are concentrated up, material incompatibility and product instability become more prevalent. Silica can also be used to overcome instability by converting concentrated liquid formulations into free-flowing powders. You can read more about silicas as flow aids and silicas as liquid carriers from our previous blog posts.

Can Plastics Be Found Within Product Formulations?

As well as the plastic packaging, plastics can also find their way into the product formulations themselves. A historical example of this is plastic microbeads that were used as mild abrasives. A current example being styrene or acrylate-based opacifiers used to alter the appearance of finished products; Their only purpose is to make a formulation look more luxurious. Generally, these bypass landfill and recycling plants and are rinsed down the drain causing environmental damage. A number of natural alternatives are now becoming available. Valida is a multi-functional additive based on fibrillated cellulose and can be used as one such example. It’s based on mechanically treated cellulose fibres, which are insoluble in water creating an effective opacification effect. It’s stable across the pH range and very tolerant to high electrolyte concentrations. It has the added benefit of stabilising the formulation, due to the creation of a 3D network allowing for the suspension of insoluble components, such as naturally derived alternatives to plastic microbeads. Further information on Valida can be found in another previous blog post about the stabilising and rheology modification effects of Valida.

Figure 3: There are lots of options to improve the sustainability of the household cleaning industry. These include removing opacifying polymers from within the formulations themselves.

Can the Plastics be Recycled?

Used plastics can be ground or melted down into small pellets and then moulded into new items. From the 1^st of April 2022, a tax was introduced for packaging that contains less than 30% recycled plastic. This was in an effort to move manufacturers away from the use of virgin plastic. It is possible, however, to purchase packaging that contains more than the 30% minimum. The quality of the plastic degrades each time it’s recycled, though. For this reason, the best balance of virgin and recycled plastic needs to be found on a case-by-case basis, depending on the type of formulation contained within. A number of benefits can be seen from recycling plastic. Recycling is significantly more energy efficient than manufacturing virgin plastic. Many of the carbon-containing compounds used to create plastic are petroleum-derived making them non-renewable. Recycling plastic reduces energy consumption and the demand for these petroleum compounds.

Summary

As illustrated above, plastic can be a difficult material to replace but there are several ways to reduce and potentially substitute plastic components for HI&I cleaning products. If plastic is necessary to use with a formulation on the grounds of compatibility, safety and practicality then employing the above tactics can go a long way to reducing the amount of plastic waste generated.