Technology, areas of application and innovations in microencapsulation
Does your laundry still smell fresh for a long time? And the carpet still smells 24 hours after you have sprayed it with a textile spray? This is due to the microencapsulation of fragrances in textile sprays, detergents or perfume advertising - the small capsules are hidden everywhere in our everyday lives. Microencapsulation is a technology that is constantly finding new applications. At the same time, it is becoming increasingly sustainable. Dr Oliver Reichel explains how microencapsulation works, how it is used and how Follmann is driving technological development forward.
How microencapsulation works
We use microencapsulation to enclose small particles or liquids in a capsule. The coating provides lasting protection for the contents and releases them in a controlled manner in the event of friction or pressure.
Since its development in the 1970s, this technology has been constantly evolving: initially, the capsules only enclosed individual substances, but today we can encapsulate complex compositions and also reproduce the capsules. Whether liquid or solid - we can encapsulate both in microcapsules. Our encapsulation process is also designed for oily liquids.
Encapsulated - and what now?
The substance in the capsule can be released again. Microcapsules open in different ways:
- Friction: Mechanical pressure causes the contents to be released. Imagine you are wearing freshly laundered clothes. The friction between your body and the fabric destroys the wall of the capsules and the fragrance is released. Follmann focusses in particular on this method.
- Diffusion: The wall releases the contents over a defined period of time. Imagine a textile spray that you can still smell for a long time.
- Temperature: At a certain temperature, the capsule releases the contents with the help of a small liquid gas balloon that expands.
You supply us with the product - we encapsulate it
At Follmann, we do not produce the inside of the capsules ourselves. For example, you supply us with a perfume that you would like to encapsulate. We then develop the microencapsulation - customised to your requirements. You then test the capsules. Through constant exchange and customisation, a microencapsulation is finally created that is precisely tailored to your application.
How we encapsulate your substances in 4 steps
This is our process for the microencapsulation of ‘oil-like’ substances:
- Oil and water are separated.
- Emulsion: Oil emulsifies in water through stirring.
- We add wall formers to the emulsion.
- Wall formers cross-link and form a wall around the oil droplets.
The result: The substance is encapsulated!
Detergents, scented paints, plant protection - microencapsulation has a wide range of applications
Microencapsulation can be found in various areas. Here are some examples:
- Household: In detergents, cleaning agents and textile sprays. The microcapsules transport fragrances to the desired location. Friction, for example on the body, releases the fragrance.
- Cosmetics: Capsules only release vitamins, fragrances and essential oils when they are applied to the skin. The ingredients remain fresh until then.
- Printing industry: In multisensory marketing, you can print scented varnishes with microcapsules on flyers and packaging. You can smell the fragrance by rubbing.
- Agriculture: Pest control is also possible with microencapsulation. This is because the capsules release biocides in a targeted manner - thus protecting the environment.
- Food: Microcapsules protect vitamins and flavours and release them during consumption.
- Pharmaceutical industry: Microencapsulation enables the targeted release of active ingredients in medicines. It also protects the active ingredients and simplifies the handling of medicines.
Under pressure: How microcapsules withstand high pressure
Scented coatings can also be found on the packaging of room scents: If you rub the small fields, you can test the fragrance. The fragrance fields with the microcapsules are printed on. But why don't the capsules break during the printing process? They are literally exposed to great pressure. Nevertheless, a light rub on the packaging is enough to release the fragrances. Innovation from Follmann makes it possible!
The walls of the capsules are made of aminoplast resin - a stable plastic with high impermeability. This makes them highly resistant to chemicals and mechanical stress. At Follmann, we also produce hot-melt adhesive - in production, we have tested that the capsules can withstand even these stresses.
A scent like on the first day
Imagine you find an old perfume advert with a field for testing the fragrance. You rub over the fragrance field and can still smell the perfume - even after 10 years. That's how long-lasting microencapsulation is: the capsules reliably protect the contents from oxygen and other external influences and keep them fresh.
The size of the microcapsules also plays a decisive role, because not all microcapsules are the same. The capsules are located in the liquid lacquer and, due to their small size, can withstand high pressure during the printing process. The capsules are only fixed once the scented lacquer has dried. Then the pressure of your finger is enough to destroy the shell and release the fragrances.
Sustainable, environmentally friendly microencapsulation
An EU directive on the restriction of microplastics entered into force in October 2023: Additional particles in cosmetics and detergents and cleaning agents will be banned in the foreseeable future. At Follmann, we have already been focussing on sustainability for some time:
A balancing act: Stable, but still environmentally friendly degradable
The requirements for the microplastic-free capsules are contradictory:
- They should protect the fragrance during storage and the wash cycle and only release their contents on clothing.
- Enzymes must also survive the capsules. This is because the detergent contains enzymes that remove stains from clothing.
- And they have to be biodegradable.
We optimised our technology until we found a suitable material for the microcapsules: Our microencapsulation for detergents is so stable that it can withstand the wash cycle and enzymes. Nevertheless, it is so unstable that the capsules degrade in sewage sludge - so no microplastics get into the groundwater.
Depending on the application, we work with two microplastic-free technologies:
- Bio-based polymers: Microcapsules are normally made of synthetic polymers. We have replaced these with bio-based polymers. The result: microplastic-free and biodegradable capsules.
- Inorganic substances: In this method, we have replaced the polymers with inorganic substances. The capsules are therefore free of microplastics and comply with current EU regulations.
Microencapsulation - a future technology
But microencapsulation can do much more. In cooperation with research institutes, we are currently working on a new technology: microcapsules could absorb heat - and release it again when it is cold. At the same time, they could cool down warm environments.
These small capsules will also play a major role in our everyday lives in the future.
