Aerospace Develops Novel Peelable Coating

7 April 2009

Peelable Coatings Picture
 

A new type of coating originally developed for military use is likely to have a much wider impact on civil protection techniques and urban environmental projects in the future.

Intergard 10220®, now on the market, was successfully developed as a temporary peelable camouflage coating with chemical agent absorbent properties as a result of a three year collaboration project between the UK Defence Science and Technology Laboratory (Dstl) at Porton Down and AkzoNobel Aerospace Coatings.

"Just as the technical imperative created by the space industry saw the launch of many new technologies that have now become part of our everyday lives, so too is the need to create a durable and flexible camouflage for the military may well result in a host of new uses for the peelable coatings elsewhere. This is how our technical expertise is driven forward." explained Robert Walker, AkzoNobel Aerospace Coating’s Business Development Manager for Defense.

The new coating meets the demand for asset protection from visual and heat seeking observation in specific environments. Further improvements to the coating’s unique ability to absorb rather than just resist chemical agents are continuing through this joint venture.

Dr. Steven Mitchell of the Hazards Management Team at Dstl explains: "We have been working with AkzoNobel for many years, mainly in testing chemical agent resistant coatings (CARC) to the relevant defense standards. There are three main areas of collaboration within the chemical, biological and radiological (CBR) defense area. These are CARC coatings, and current generation peelable coatings; and next generation super-absorbent coating systems, which are still at the development stage."

The introduction of Intergard 10220 has solved a number of problems previously encountered in the camouflage of military vehicles, such as paint removal, quick camouflage change, and chemical agent decontamination. Traditional systems involved the application and subsequent removal of coatings using solvents, chemicals and abrasion, a messy and time-consuming process which also required the safe disposal of the solvent and solid residues afterward, itself a costly business. Then came the ‘old style’ temporary camouflage coatings often referred to as TCC. These required specialist chemicals for removal and specialist equipment to stop leakage into the water table. The Intergard 10220 TPC (Temporary Protective Coating) generation of peelable coatings, on the other hand, can simply be peeled off when necessary either to suit the needs of different terrains, or in order to decontaminate the surface of the vehicle, with any remaining residue removed by a water power washer, the peeled coating can then be collected and incinerated limiting any environmental damage. Overall, the Intergard temporary protective coating offers considerable savings in time, materials and cleaning chemicals, compared to over-coating with conventional paints and temporary camouflage coatings.

The peelable coating can also be modeled to change the IR (infra red) signature, helping to camouflage equipment in different spectra relevant to the operational environment, reducing observation and further protecting personnel.

Looking back over the development of Intergard 10220, Dr. Mitchell required the coating to do several jobs simultaneously as the key drivers of the project. "The main reason for applying this type of coating is to help conceal the vehicle. It therefore has to be the right color and have the right infra-red or solar heat reflecting properties. It must also be durable, yet peelable. On top of this it must function correctly when contaminated with CBR materials."

Trials of Intergard 10220 in various countries have resulted in very positive feedback from operatives. In the quest for the ultimate camouflage/decon system, Dr. Mitchell acknowledges the importance of developing a successful peelable camouflage system that performs well in real world situations.

"There is a lot that can be achieved with current products. As part of a binary decontamination process (the combination of a peelable coating and more traditional liquid decontamination) laboratory data show substantial increases in cleaning efficiency. We have also recently developed an improved decontaminant based on micro emulsion technology. When used as part of a binary decontamination process it complements the peelable coatings well. It is important to remember that peelable coatings do not offer the complete solution to vehicle decontamination as there are areas – such as tracks and running gear that cannot be coated."

The next stage in the joint project is to further develop the coating’s absorption rate of chemical agents therefore significantly improving the decontamination properties of peelable coatings. This is currently ongoing.

"We try to make sure our decontamination systems can deal with the full range of likely contaminants," Dr. Mitchell continued. "We have three main concerns. The first is chemical liquids, specifically those that are persistent in the environment, including those that have been thickened in their dissemination. The others are biological and radiological particulates. It’s a common misconception that well known chemical agents such as sarin or mustard are gasses. They are in fact liquids. Gases do not present a contamination problem as they do not persist in the environment."

He explained that traditional approaches to decontamination rely on the use of a decontaminant. "Liquid chemical agents are excellent at penetrating cracks and crevices and will be drawn into any complex features of a vehicle’s surface, such as rivets and panel joints, making them difficult to remove. The advantage of a pre-applied peelable coating is that it limits the extent of this penetration and, when peeled as part of the decontamination process, can improve the level of removal achieved. The same is largely true of biological and radiological particulate contamination."

Improving the absorbency, however, has distinct advantages. "Liquid chemical agent on a contaminated surface presents a constant hazard to personnel," Dr. Mitchell continued. "The more absorbent a coating is, the more this contact hazard can be reduced. This absorbance requires no action on the part of the user, acting as a ‘do nothing’ hazard reduction process on contamination, which is highly desirable!"

Dr. Mitchell is clear about the benefits of a partnership approach. "The best example is our current project on developing a next-generation super-absorbent coating. At the start of the project we both brought complimentary areas of expertise to the table. AkzoNobel clearly have a lot of expertise in the design and production of coatings. We were able to identify possible absorbent materials from a history of studying chemical agent absorbance and can offer state-of-the-art testing facilities. We test the prototype coatings AkzoNobel develop at their facilities and the data is fed back to inform the optimization of the next batch of prototypes. This collaborative approach is starting to show significant success in improving absorbance."

The project to develop a super absorbent system is looking at both one and two coat (absorbent over peelable) options. Looking even further ahead, the ideal would be a coating that also changed color on contamination/ decontamination to notify personnel that the equipment has in fact been contaminated, but as Dr. Mitchell explained, this relies on the development of some sophisticated underpinning chemistry to produce the colors. This technology is still some way off.

Akzo Nobel’s Robert Walker has from the beginning championed the development of Intergard 10220. "Working with Dstl, an institution that is world renowned, on the developments of a defense and civil coatings immediately informs other international establishments that the science behind our products and their performance is robust," he explained. "They know that the testing and development process will stand up to scrutiny."

"The development procedure is also a very useful one for our own chemists, who learn a great deal about the environments and capabilities our defense products have to face now and in the future."

However, with the increased need to protect civilians from international terrorism, interest in the defensive and decontamination properties of coatings is no longer just for military use. The same threats that have concerned the protection of military hardware and personnel now have to be prepared by civil protection agencies. A coating that offers a new approach, such as a peelable coating, was inevitably going to attract interest.

AkzoNobel report that authorities around the world are looking at the peelable coating’s potential role in the protection of vulnerable infrastructure such as stadia or government buildings against all forms of contamination including radiological, chemical and biological.

The versatility of a purely peelable product by AkzoNobel also has ramifications in the protection and enhancement of the environment. The future developments of this versatile technology could, for example, be developed to cut the cost of removing graffiti from structures – simply peeling it off could be quicker and cheaper than current techniques. It can also be used as an easily removed temporary protection during the construction of large projects, such as ships. In these circumstances, sections of the superstructure are painted as they are completed, but by the time the project is finished they often need painting again to cover wear and tear. A peelable protective coating would be an ideal alternative.

Police forces too are interested in the implications of peelable coatings with different infra-red signatures for tracking and tracing.

"Once the concept is explained and understood, civil authorities have been quick to see uses for the product that not only has the potential to save lives or improve operational efficiency but to cut costs, the sort of win-win situation governments can benefit from," Robert Walker added.

"As far as AkzoNobel are concerned, the wider use of this technology helps to justify the development cost and open new markets for us."

The peelable coating, Intergard 10220, has been approved to DEFSTAN 80-220, and is being evaluated against the performance requirements of a range of international specifications including Stanag 4360, MIL-DTL64159 (two part material) and Mil-DTL53039 (one part material). It also meets NATO decontamination standards. Anyone interested in learning more about the product can visit the AkzoNobel Aerospace Coatings stand at DSEi in London September 8th-11th 2009 or contact AkzoNobel Aerospace coatings for further information.