Migrating and its significance in cosmetic packaging
The development and safety of modern cosmetic products depends not only on innovative formulations, but also on the right packaging. This is because complex interactions can occur between the contents and the packaging material, which are summarised under the terms diffusion, sorption, migration and permeation. Migration in particular plays a central role in the cosmetics industry and is strictly monitored to ensure product quality and safety.
Definition of key terms
Diffusion refers to the transport of particles due to Brownian motion. The driving force behind this is always a concentration equalisation.
In plastics, this means that molecules move towards a concentration gradient and can thus penetrate into new areas of the material. Sorption encompasses adsorption and desorption at interfaces. Substances from a filling material are deposited on the surface of the packaging or detach themselves again. A sub-process is absorption, in which molecules penetrate into the amorphous areas of a polymer. This is relevant in cosmetics, for example, when packaging absorbs fragrances or oils. Migration refers to the transfer of substances between packaging and contents. This applies to the transport of plastic additives or monomers from the packaging into the cosmetic product as well as the reverse path of product components into the packaging material. Liquid formulations such as emulsions or serums are particularly susceptible to migration.
Permeation refers to the transport of substances through the packaging, for example from the environment into the cosmetic product or vice versa. This process is particularly relevant when it comes to the shelf life and stability of sensitive active ingredients.
Migrating is a key phenomenon.
In the cosmetics industry, migration is a decisive quality and safety criterion. Additives, plasticisers or residual monomers from plastics can migrate into the formulation and thus influence properties such as odour, colour or stability. Conversely, fragrances, essential oils or UV filters can also migrate from a formulation into the packaging material.
The intensity of migration depends on various factors.
– Molecular size of the migrating substance,
– Polarity and solubility
– Type and structure of the polymer
– Contact time between product and packaging
– Storage temperature and light conditions.
All these factors explain why manufacturers must carry out careful packaging tests when developing new products.
Packaging phenomena in practice
Liquid and semi-solid formulations such as emulsions, gels or oils play a particularly important role in cosmetics. Typical phenomena that can occur as a result of migration are:
– Changes in odour due to the absorption or release of fragrances
– Instability in emulsions due to the sorption of lipophilic components.
– Loss of UV filters in light-transparent packaging.
– Colour changes due to reactions of migrating additives.
To avoid this, companies rely on suitable material combinations, for example glass, high-barrier plastics or multi-layer systems.
Migrating and cosmetics development
When developing cosmetic products, packaging is therefore incorporated into the process at an early stage. The formulation and packaging materials must be optimally coordinated to minimise migration and other interactions. For private label or branded products, this means that packaging must perform technological protective functions in addition to marketing purposes.
A sound understanding of migration is essential, especially in times when consumers value safety and transparency.
Conclusion
The terms diffusion, sorption, migrating and permeation describe the physical and chemical processes that can take place between cosmetic products and packaging. Of these phenomena, migration is the central issue, as it has a direct influence on the stability, efficacy and safety of products.
We keep these aspects in mind during every product development and support our customers in creating safe and high-performance cosmetic products. Please do not hesitate to contact us if you have any questions or would like individual advice.
Literature
Piringer O. G. Packaging for food – suitability, interactions, safety, VCH Weinheim, 1993
Christine Rück – Investigation of the permeation of polyacrylate-based label adhesives through pharmaceutical plastic containers (dissertation, Free University of Berlin, 2009)
The dissertation is available as a PDF file via the digital repository of the Free University of Berlin, Refubium. You can download the complete PDF file directly at:
https://refubium.fu-berlin.de/bitstream/handle/fub188/9602/Dissertation_Christine_Rueck.pdf