A unique new stab and flame-resistant material has been made using wool and a special synthetic fibre. It looks and feels like regular wool jacket fabric and is lightweight and comfortable to wear.
The fabric is made from a core structure of knitted synthetic Vectran™ yarns with short wool fibres packed into the knitted structure. Developed at AgResearch in Christchurch, this fabric opens up new opportunities for protective clothing where traditional stab and flame-proof fabrics would be unsuitable.
Fibre combination provides dual protection
The wool and Vectran™ fibres work together to give a better level of protection than you would get from either fibre alone.
Vectran™ is a very high-strength fibre, spun from a special type of polyester. It has excellent cut and impact resistance, which means it can withstand the force of a sharp object. It also remains stable at high and low temperatures, so it won’t burn. Other uses for Vectran™ fibre include cut-resistant gloves for the meat industry, aircraft cables and astronaut safety tethers.
Wool is also flame retardant. When exposed to a flame, it chars, forming a layer of carbon. The charred layer is held together by the Vectran™ structure creating a protective barrier that reduces heat transfer through the fabric, so the fabric doesn’t burn and also doesn’t get too hot and burn the skin on the other side.
Wool adds comfort and wearability
There are other stab and flame-resistant fabrics made from synthetic yarns, such as Kevlar and Nomex, that provide a similar level of protection. The idea of incorporating wool into the fabric is what makes it different. It looks like a normal wool jacket fabric and is comfortable to wear all the time.
The properties of wool make the fabric more comfortable because it’s breathable and absorbent. It’s also soft and springy to touch.
Knitted structure adds flexibility
The other factor that makes the fabric different and adds to its comfort is that the Vectran™ framework of the fabric is knitted. This is more flexible than a woven structure, so it doesn’t restrict movement.
New market opportunities
It’s comfortable enough to wear all the time so is ideal for situations where there’s a more moderate level of risk such as ambulance officers, bouncers and security guards. It could also be used where there’s risk of an accidental cut or injury in occupations such as forestry or metalworking and in recreational activities such as mountain biking or hunting.
Get more information about developing new stab and flame-resistant fabrics.
Making the fabric
- Wool preparation: Wool fibre undergoes a number of processes before it is ready for making into fabric. This preparation produces a sliver of wool fibres.
- Fabric construction: The Vectran™ yarn and wool sliver are fed into a special machine called a Fibreknit machine. This machine knits the Vectran™ yarn and locks in the wool fibres at the same time.
- Fabric finishing: Special finishing processes strengthen the fabric and help lock in the wool fibres.
Challenges working with high-strength yarn
During the knitting process, a yarn undergoes a lot of strain causing stretching. Very high-strength yarns like Vectran™ don’t stretch. This creates a lot of pressure and can cause parts of the machine to break.
This affects how fast you can produce the fabric because, as the speed of production increases, the forces acting on the yarn increase. As a result, you have to start slowly, build up speed gradually and stop when problems occur.
A cut-resistant fabric also presents some issues for cutting out and manufacturing garments.
Useful link
An introduction to Vectran™ fibre and its properties.
