What is Lyocell Fiber? How is it Modified by Flame Retardant Finishing?

Flame retardant finishing is the method that coat flame retardant agent on the fiber surface during the production or after the fiber ready. This method is easy to carry out, but the hand feeling is poor and non washable, this method usually used for Lyocell FR fiber. Lyocell fiber is a new renewable cellulose fiber, its physical and chemistry property is similar to Viscose fiber, but its production technique is more similar than viscose fiber, it uses NMMO solvent, the production process simple, the solvent can completely recycle, there is no problem of wastes and no harm to the environment.

 

As the construction of Lyocell fiber is same with other cellulosic fibers, so the FR agent that used for other cellulosic fibers almost can used for the Lyocell fiber, but the production process before spinning is hermetically, so Lyocell fiber mainly use FR treated. Pyrovatex CP and Proban CC all contain the organic phosphorus and nitrogen, can create polymer type stable and permanent flame retardant cellulose fiber by cross-linking reaction, which used for FR finishing of Lyocell fiber. Pyrovatex CP FR agent is amine phosphate construction, its application is widely. When the Pyrovatex CP agent and anti-wrinkle resin finishing agent use for Lyocell fiber together, Methyl amine phosphate bond to C6 from glucose repeating unit of cellulose fiber to form a link which is can washable for normal washing procedure, but can’t resistant to bleach, so must use the correct application method.

 

The FR treated of Lyocell fiber takes 5min at room temperature, then cross-linking takes 3min under 160℃, then completed. The washable, color, hand feeling and strength etc. Physical performance of Lyocell fiber all is good, after mechanical washing and dry 50times, the LOI still more than 26%, the content of phosphorus remains at the level of 1.0%.

 

The FR treated process to Lyocell fiber and blended fabric by using the method of Proban is as following, padding--drying--ammonia fume--alkali washing--water washing--drying.