2010-Obtaining Flame Retardant Cotton Fabrics from Silicone-based Compounds by Plasma Processes

Obtaining Flame Retardant Cotton Fabrics from Silicone-based Compounds by Plasma Processes

Vladimir Totolin, University of Wisconsin-Madison


Introduction

Flame retardants (FR) and flame-retarded textiles are prevalent in all aspects of our daily lives.
They are present in upholstered furniture, curtaining, home furnishings, car seats, in the workplace and in all public areas, including trains and passenger aircraft. Flame retardants are chemicals added to polymeric materials, both natural and synthetic, to enhance their flame-retardant properties.
Flameretardant chemicals are most often used to improve the fire performance of low-to-moderate cost commodity polymers. These flame retardants may be physically blended with or chemically bonded to the host polymer. They generally either lower ignition susceptibility or lower flame spread once ignition has occurred. Some polymers are inherently less flammable due to more stable polymeric structures; these are usually higher priced engineering plastics such as polyimides, polybenzimidazoles and
polyetherketones1.
In other natural or synthetic polymers (which are flammable) the most significant
step in the burning process is the fuel production stage where thermal energy induces bond scission mechanisms that result in the formation of volatile molecular fragments. These low molecular weight compounds diffuse into the surrounding environment and generate flammable gasses which initiate the combustion. Modifications can be made to alter the material’s flammability in the various stages of the burning process, which include heating, degradation and decomposition, volatilization, and oxidation2.
Most flame-retardants decrease flammability by increasing the formation of char and/or reducing the formation of volatiles in the solid/condensed phase, or by inhibiting oxidation in the gas/vapor phase3. The simplest methods of modification involve the addition of water-soluble acid ammonium phosphates and borates. More sophisticated and more durable finishes use phosphorus compounds in conjunction with urea and melamine resins to create a cross-linked finish with the cellulose4.
This type of finish is applied via a pad/dry/cure method5. Undesired problems occurring from these finishes include yellowing from heat curing and acid damage, alteration of fabric hand, as well as degradation or total loss of mechanical properties1-5. Thus, over the years, it has been an increasing demand to replace both antimony- halogen systems in textile back coatings and formaldehyde- free treatments in durable finishes.
Therefore, the number of new articles, patents and products associated with silicon-based
flame-retardant (FR) systems is evidence of renewed interest in FR approaches that do not rely completely on halogens or phosphorus.