Polyurea spray coatings can add some really amazing properties to otherwise fragile structures in a matter of minutes. If you’ve never seen it, a video search can show loose stacks of concrete blocks, Styrofoam coolers, and even watermelons made indestructible after just “painting” them with this stuff.
Polyurea is a long-chain elastomer of isocyanates and amines that form urea compounds at their intersecting joints.
…which is a detail you’d be hard-pressed to even find a use for in a career playing trivia games at your local pizza shop. The important part here is that there are long molecular chains of strong bonds that link together with a compound called “urea”. There are many of these links, hence the “poly” part of the name. One benefit of these chains of molecules being long and complex is that they hold firm and absorb a lot of energy and can reorient between the interlinking bonds to stretch.
This makes the material unexpectedly strong and flexible at the same time. While specific polyurea formulations might vary, they are easily many times stronger and many times more flexible than epoxy. These compounds achieve around 6000 psi tensile strength and 500%-800% elongation before breaking, with certain blends achieving over 250,000psi strength! By comparison, mild steel has a tensile strength of just 50,000-65,000psi. And all of this from a spray coating!
How is this useful?
Think about it. You can essentially spray a flexible, waterproof coating with the strength of steel onto any shape. There are no VOCs. It sets to the touch in just seconds and cures to full strength within hours. Some recently developed polyurea based materials are even self-healing at room temperature – and this on a molecular level, which means it can heal itself over and over again in the same place.
The military certainly took notice. These compounds have been used in military vehicles and buildings to improve armor and reduce shrapnel from roadside (or underwater) bombs without adding significant weight. This is something the Army, Navy, even the Pentagon has taken advantage of.
Photo by Roger Starnes Sr on Unsplash
Commercially, polyureas are used to seal and protect building roofs providing long maintenance-free performance.
Perhaps one of the most popular and familiar uses is for spray-on bed liners. Under the popular brand “Line-X”, polyurea coatings are applied to a whole array of automotive and recreational vehicle parts.
Boat hulls are coated below the waterline for protection from abrasion and corrosion. Polyurea coatings here last about 8x longer than traditional coatings in these harsh marine environments.
These compounds are formulated by major chemicals or coatings companies like 3M and BASF. Specific formulations will vary in strength and flexibility and can be pigmented as desired. Some are even approved by FDA / USDA for food contact.
Consider where polyurea coatings might bring the level of performance you need to your products.
CDN Inc. is a product design and engineering firm that can adapt easily to your project needs; engineering, industrial design, prototyping & manufacturing.