Flame Resistant Finishes

7/24/2019 Flame Resistant Finishes

1/32

+

Flame resistantFinishesFabric and Garment Finishing


2/32

+Introduction

Many terms are used when discussing the ability of a fabric toresist ignition, burn more slowly than normal or self extinguishonce the source of ignition has been removed from the fabric.

The following are from the American Society for testing andmaterials (ATM! "

# Fire $etardance " The resistance to combustion of a materialwhen tested under s%eci&ed conditions

# Fire $esistance " The %ro%erty of a material whereby 'amingcombustion is %revented, terminated or inhibited followinga%%lication of a 'aming or non 'aming source of ignition, withor without subseuent removal of the ignition source.


3/32

+ Flammability " The characteristics of a material that relate

to its ease of ignition and its ability to sustain ignition.

The Burning Process

The mechanism of burning is a relatively simple process. Ignition

source is the requirement for the combustion to start. This

produces decomposition of the textile material which results intorelease of flammable gases. In the presence of oxygen in the

atmosphere, these ignite and form a flame.

In this combustion process large amounts of heat generated in the

process causes further decomposition of the textile and spreads

the combustion.

Two processes are involved in the combustion process : Flamming

andAfter glow.


4/32

+ Flammingis the persistence of flame in the material even afterextinction of the flame.

After Glowrefers to the material emanating a glow afterextinction of the flame

For a flame resistant fabric, It is not necessary that their will be

glow resistance. hen there is resistance to both, it is !nown

as " Fire resistant.

A flame retardant fabricdoes not propagate the flame

although it may burn or char when sub#ected to any form of

heat.

A fabric may be flame retardant and yet glow after removal ofsource of heat. This effect is !nown as $After Glow% or $Flame

less combustion% and is harmful as it gives out heat and also

pollutes the atmosphere.


5/32

+A%%lications

A%%lication via conventional %adding techniues

Multi%le di%s and ni%s

)* to +* seconds of dwell time for good results

%timal %- /.*

Amount of 'ame retardant needed de%ends %rimarily

on the fabric ty%e, a%%lication conditions and testcriteria to be met.


6/32

+Mechanisms

Flame resistants can act physically or chemically and

sometimes both by physically and chemically interfering at

particular stages of burning. The different mechanisms are:

Endothermic Degradation :&ertain compounds brea! down

endothermically when they are sub#ected to high temperatures.

'agnesium and aluminium hydroxides are such examples.

(arious hydrates also act similarly. The reaction ta!es off heat

from the surroundings, thus cooling the material.


7/32

+ Dilution of Fuel:ubstances, which evolve inert

gases on decom%osition, dilute the fuel in the solid andgaseous %hases.

Inert &llers, eg. talc or calcium carbonate, act asdiluents, lowering the combustible %ortion of thematerial, thus lowering the amount of heat %er volumeof material that it can %roduce while burning. Thus the

concentrations of combustible gases fall under theignition limit.

Thermal Shielding :A thermal insulation barrier iscreated between the burning and the yet#to#burn %arts.

Intumescent additives are sometimes a%%lied that turnthe %olymer into a carboni0ed foam, resultantlyse%arating the 'ame from the material and slowingdown the heat transfer to the unburned fuel.


8/32

+

Dilution of Gas Phase :Mostly carbon dioxide and water, act asdiluent of the combustible gases, lowering their %artial %ressures andthe %artial %ressure of oxygen, thus slowing the reaction rate. Thesegases are %roduced by thermal degradation of some materials.

Gas Phase Radical Quenching :1hlorinated and brominatedmaterials undergo thermal degradation and release hydrogenchloride and hydrogen bromide.

These react with the highly reactive #- and #- radicals in the 'ame,resulting in an inactive molecule and a 1l or 2r radical. The halogenradical has much lower energy than #- or #-. and thus has muchlower %otential to %ro%agate the radical oxidation reactions ofcombustion.

Antimony com%ounds tend to act in synergy with halogenated 'ameretardants. The -1l and -2r released during burning are highlycorrosive, which has reliability im%lications for ob3ects sub3ected tothe released smo4e.


9/32

+

There are many categories in which 'ame resistors can be divided.The ma3or categories among them include"

Tetra4is (hydroxymethyl! %hos%honium salts that are made by%assing %hos%hine gas through a solution of formaldehyde and amineral acid li4e hydrochloric acid. This category is mostly used

as 'ame retardants for textiles.

Minerals li4e asbestos, com%ounds such as aluminum hydroxide,magnesium hydroxide, antimony trioxide di5erent hydrates, red%hos%horus, and boron com%ounds, mostly borates etc.

ynthetic materials, usually halocarbons which includeorganochlorines such as %olychlorinated bi%henyls (612s!,chlorendic acid derivates and chlorinated %ara7ns8organobromines such as %olybrominated di%henyl ether (629:s!,organo%hos%hates in the form of halogenated %hos%horuscom%ounds and others.

1ategories of Flame $esistors


10/32

+Types of ame retardants are"

1hlorinated 'ame retardants

6hos%horous#containing 'ame retardants (6hos%hateester such as Tri %henyl %hos%hate!

;itrogen#containing 'ame retardants (i.e. Melamines!

Inorganic 'ame retardants.

ther method of classifying Flame $etardants is to dividethem as Inorganic, rgano 6hos%horous, -alogenated

organic and ;itrogen based com%ounds. -alogenatedorganic 'ame retardants are further classi&ed as havingeither 1hlorine or 2romine which is %o%ularly 4nown as2rominated Flame $etardants (2F$!


11/32

+9rawbac4s

)tiffening and loss of fabric drapability

)ignificant strength loss in fabric

*oss of finish in laundering +nondurable- and ineffectiveness when

laundered in household bleach, with soaps, or with water softeners.

The best of the flameretardant finishes available for cotton are T/&0

types, which are used extensively for children1s sleepwear.

The finish is durable to 23 or more launderings, does not affect fabric hand,

and does not contribute to fabric strength loss.

The problem, however, is that these finishes cannot be used with chlorine

bearing household bleaches or laundry soaps.

They must be used with high phosphate detergents.


12/32

+Factors to be considered while

selecting %ro%er 'ameretardants Fiber content

end use

method of cleaning

desired hand

drapability


13/32

+tandards and Test methods


14/32

+

1alendaring


15/32

+A!"#DAR$#G

1alendaring is a %rocess where fabric is com%ressedby %assing it between two or more rolls undercontrolled conditions of time, tem%erature and%ressure.

It is a ty%e of mechanical &nish

6roduces di5erent ty%es of surface a%%earance

e calendering

?. :mbossed calendering

/. Moir@ calendering

+. chreiner calendering


16/32

+b3ects of 1alendering

To im%rove the fabric handle and to im%art a smoothsil4y touch to the fabric

To com%ress the fabric and reduce its thic4ness

To reduce the air %ermeability by closing the threads

To increase the luster

To reduce the yarn sli%%ageTo increase the o%acity of the fabric

urface %atterning by embossing


17/32

+ %& S$'P!" A!"#D"R$#G

It is a high s%eed, high %ressure %ressing of fabric (


18/32

+


19/32

+(& G!A)"D A!"#D"R$#G

It is a calendering &nish to %roduce highly gla0ed shined %olished cotton

The calender machine used is a friction calender

ne cylinder of highly %olished steel cylinder rotating

at s%eed much higher than the fabric %assing throughit

Fabrics are &rst treated with starches or resins beforecalendering

The s%aces between the yarns are thus &lled u% andgla0ed a%%earance is obtained

Gla0ed calendering using starch are semi#durable

Gla0ed calendering using resins are durable


20/32


21/32

+ *& ie calendering It is a ty%e of gla0ed calendering -ere, the friction roller

rotates at s%eed much greater than ordinary friction

calendering

The resulatant fabric become highly lustrous and ta4es on awet loo41otton, rayon, %olyester, nylon and blends can begiven cire &nish

Fabrics are however, treated with waxes and resins beforefriction calendering

-ighly %olished e5ect is %roduced

Dhen thermo%lastic fabrics are ci>e &nished, they becomes

moderately water#re%ellent 9ue to 'attening

9ue to %artially fusing of &bres


22/32


23/32

+,& "m-ossed calendering

It is a calendering in which a three#dimensional design iscreated on a fabric

This is done on a s%ecial embossing calender in which theroller cylinder is engraved with the embossing design

The %attern is then %ushed or sha%ed into the cloth when thefabric %asses between the rollers

ome embossed fabrics are made to imitate more costlywoven 3acuard or dobby designs

:mbossed %atterns of fabrics treated with resins and curedafter embossing are durable

:mbossing of fabrics of thermo%lastic &bres are %ermanentbecause the heated metal roll heat#sets the design


24/32


25/32

+


26/32

+ .& 'oir/ calendering

The moir@ &nish %roduces a wood#grain design on the

face si0e of the fabric

Moir@ &nish can be tem%orary, durable or %ermanent

1otton or rayon moir@ &nish is tem%orary without%retreatment with resin

9urable moir@ &nish reuires initial resin treatmentfollowed by calendering

Moir@ &nish on thermo%lastic &ber fabrics are%ermanent if a heated roller is used for calendering

Methods of %roducing moi>e Bsing engraved cylinder

Bsing smooth calender roller


27/32

+ Bsing engraved cylinder

In this case engraved roller is used on the calender roller

1alender roller 'attens one %art of the fabric more thanother, causing di5erent light re'ectance

The di5erent light re'ectance cause moire e5ect

9e&nite re%eat %attern moi>e is %roduced

Bsing smooth calender rollersTwo fabrics, each face to face, are fed through the

calender

$ibbed fabrics are mainly reuired for this

The high %ressure on the calender rolls causes the rib tosuee0e into each other in certain areas

1reates light re'ectance %attern which %roduces moi>ee5ect

The e5ect is com%letely random and has no s%eci&c%attern


28/32

+


29/32


30/32

+ 0& Schreiner calendering chreiner calendering %roduces a low, soft#4ey lustre on the

fabric surface

9istinct from the high gla0e of the gla0ing calender or the lustreshine of the sim%le calender

To %roduce this e5ect, one of the steel cylinders of the calender

is embossed with &ne diagonal lines. These embossing arebarely visible in na4ed eye

Didely used on cotton E cotton%olyester sateen

chreiner calendering may be %ermanent, durable or tem%orary

&nish Is %ermanent if the &bre is thermo%lastic

Is durable if the fabric is resin treated but not cured

Is tem%orary if the &bre is non#thermo%lastic and not treatedwith resin


31/32


32/32

T1A#2345

Documents

Flame Resistant Finishes