11-12-2012, 01:11 PM
Phosphorus Flame Retardants for Textiles
[attachment=43338]
How Do Textiles Burn?
•Cellulose decomposes (in oxygen) to tarry
depolymerization products, notably levoglucosan
• Then to volatile combustible products such as alcohols,
aldehydes, ketones and hydrocarbons
•Flammable gases ignite
•After flaming, the carbonised residue slowly oxidises
(smoulders) until it has been consumed
The Action of a Phosphorus Flame Retardant
There are Potentially Four ways of Disrupting Combustion
• Removal of heat or application of cooling. Achieved
by treating the material with heat absorbing materials.
• Increase in pyrolysis temperature i.e. glass fibre,
aramids, carbon fibres
• Elimination of oxygen from combustion zone i.e.
halogens
• Prevent evaporation i.e. form char - Phosphorus
The Action of a Phosphorus Flame Retardant
• Application of ignition source
• Formation of phosphorus pentoxide and phosphoric
acid
• Dehydration of cellulose occurs
• Dehydration reduces the temperature of
decomposition (275-325°C as opposed to 375°C for
untreated cotton)
• Evolution of levoglucosan inhibited
• Flammable tars and gases reduced, char increased
• Formation of protective layer of char
Synergistic Effect of Nitrogen
• Nitrogen catalyzes the cellulose phosphorylation
• The retention of phosphorus in the char may be aided
by nitrogen
• Release of nitrogen gas which dilutes the flammable
gases and reduces flaming
• Higher levels of nitrogen may allow lower levels of
phosphorus in the flame retardant
Flame Retardants for Polyester fabrics (Top Treatments)
• Cyclic Phosphonate Ester based
products may be used
• Applied by pad, dry, heat cure
process
• Durable to washing
• Phosphorus FR’s lower the
melting point of polyester fabrics
allowing the fabric to melt away
from the ignition source more
easily
Non-Durable Flame Retardants (Top Treatments)
• Need for more sophisticated flame retardants for higher processing
speeds and more demanding applications
• Phosphonates generally have higher thermal stability than APP’s
allowing higher processing speeds
• Flame Retardants capable of being processed at temperatures of over
130ºC have been developed by Rhodia and marketed under the
AMGARD® trademark
• Some of the AMGARD® products are based on phosphonate chemistry
which generally have higher thermal stability than APP’s
[attachment=43338]
How Do Textiles Burn?
•Cellulose decomposes (in oxygen) to tarry
depolymerization products, notably levoglucosan
• Then to volatile combustible products such as alcohols,
aldehydes, ketones and hydrocarbons
•Flammable gases ignite
•After flaming, the carbonised residue slowly oxidises
(smoulders) until it has been consumed
The Action of a Phosphorus Flame Retardant
There are Potentially Four ways of Disrupting Combustion
• Removal of heat or application of cooling. Achieved
by treating the material with heat absorbing materials.
• Increase in pyrolysis temperature i.e. glass fibre,
aramids, carbon fibres
• Elimination of oxygen from combustion zone i.e.
halogens
• Prevent evaporation i.e. form char - Phosphorus
The Action of a Phosphorus Flame Retardant
• Application of ignition source
• Formation of phosphorus pentoxide and phosphoric
acid
• Dehydration of cellulose occurs
• Dehydration reduces the temperature of
decomposition (275-325°C as opposed to 375°C for
untreated cotton)
• Evolution of levoglucosan inhibited
• Flammable tars and gases reduced, char increased
• Formation of protective layer of char
Synergistic Effect of Nitrogen
• Nitrogen catalyzes the cellulose phosphorylation
• The retention of phosphorus in the char may be aided
by nitrogen
• Release of nitrogen gas which dilutes the flammable
gases and reduces flaming
• Higher levels of nitrogen may allow lower levels of
phosphorus in the flame retardant
Flame Retardants for Polyester fabrics (Top Treatments)
• Cyclic Phosphonate Ester based
products may be used
• Applied by pad, dry, heat cure
process
• Durable to washing
• Phosphorus FR’s lower the
melting point of polyester fabrics
allowing the fabric to melt away
from the ignition source more
easily
Non-Durable Flame Retardants (Top Treatments)
• Need for more sophisticated flame retardants for higher processing
speeds and more demanding applications
• Phosphonates generally have higher thermal stability than APP’s
allowing higher processing speeds
• Flame Retardants capable of being processed at temperatures of over
130ºC have been developed by Rhodia and marketed under the
AMGARD® trademark
• Some of the AMGARD® products are based on phosphonate chemistry
which generally have higher thermal stability than APP’s