Fire Retardant finishing
protecting the fibre from easy firing is know as Fire retardant finish.
It is a Chemical and
property giving finish.
Purpose
Cotton and Regenerated rayon’s catch fire and causes fire hazards and fire accidents at home particularly while in cooking
Children's cloth are susceptible to this hazard. The men who are working in Fire service Department should wear only this type of ire retarded fabrics to protect catching of fire when they are working.
It defense for tents, ropes, baggage, parachutes.,
in industry for uniforms in ammunition factories fabrics given flame retardant
finish are used It is therefore necessary to make the fabric Flame proof for
many reasons. This finish is also essential for Curtain hangings, Decorative,
Furnishing etc.,
Requirement
The fabric should not adversely affect the fastness property of the dyed material, shade and tone, feel, handle and should not cause any irritation to the skin.
The finish should be fast to wash, light and
laundering.
Process
(A) Mechanism of Flame proofing is
Reducing the oxygen
content of fibre and /or
Increasing the moisture content of fibre.
(B) Flame proofing car be done by
Precipitating insoluble
metallic compound or
By depositing soluble metallic salts.
Theory and mechanisms of flame retardancy
1 Coating theory
Flame retardance is due to
formation of a layer of a fusible substance which melts and forms a coating
thus excluding the air necessary for the propagation of flame. Carbonates and
ammonium salts liberates gases like CO2 Nh3 and exclude air
2 Gas theory
The flame retardant
decomposes at burning Temperature and evolves non combustible gases which
obstruct and dilute the combustible gases. E.g. Mixtures of titanium and
antimony oxides.
3 Thermal theory
Heat supplied from the source is conducted
from the fibres very rapidly that the fabric never reaches the temperature of
combustion.
4. Chemical theory
The flame retardants react with cellulose on
burning and forms chemicals such as phosphoric and sulphuric acid which are
dehydrating agents, these bring about catalytic dehydration of cellulose which on
combustion produces mainly carbon and water.
