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TEXTILE FINISHING
WATER REPELLENT & WATER
PROOFING OF TEXTILE SUBSTRATE
PRESENTED TO
Dr HANEEF
MEMON
15-07-2010
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GROUP MEMBERS :
1 :M. ZUBAIR ANWER
2 :M.SOHAIB HASSAN
3 :TAIMOOR MAJEED
4 :S.M WALEED
INDUS INSTITUTE OF HIGHER
EDUCATION
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Stain Repellency :
Stain repellency is the ability of a treated fabric to withstandpenetration of liquid soils under static conditions involving only
the weight of the drop and capillary Forces.
Oil Repellency :
Oil repellency is tested by placing a drop of oil on the fabric and
observing whether the drop resides on top the fabric orwhether it penetrates.
The lower the surface tension of the liquid, the better thefabric's resistance to oily stains.
Water Repellency :
Water Repellent fabrics are those which resist being wetted bywater, water drops will roll off the fabric.
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Water Repellent Fabrics :
Water repellent fabrics have open pores and arepermeable to air and water vapor. Water-repellentfabrics will permit the passage of liquid water onceHydro-static pressure is high enough.
Water-Proof Fabrics :
Water proof Fabrics are resistant to the penetration of
water under much higher hydrostatic pressure than arewater-repellent fabrics. These fabrics have fewer openpores and are less permeable to the passage of air andwater vapor
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Physical Chemistry Of Wetting :
Where:
L/V = the interfacial energy between liquid/vapor
S/L = the interfacial energy between solid/liquid
S/V = the interfacial energy between solid/vapor
= equilibrium contact angle
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Surface free energy
when the surface tension of the liquid is lower than the
surface free energy of the solid, the liquid willspontaneously wet the solid.
The surface free energies of typical textile solids are as
follows:
Solid Surface Free energy mN/m
Polyamide (Nylon 6.6 ) 46
Cotton 44
Polyester 43PVC 39
Polyethylene 31
Polysiloxane, typical silicone oil 23-24
PTFE 18
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Repellent Finishes
For fabrics to be water repellent, the Surface free energyof the fibers surface must be lowered to about 24 to 30mN/m. Pure water has a surface tension of 72 mN/m sothese values are sufficient for water repellency.
Paraffin Waxes
The oldest and most economical way to make a fabric water
repellent is to coat it with paraffin wax.
Solvent solutions, molten coatings and wax emulsionsare ways of applying wax to fabrics.
Wax emulsions are the most convenient products for
finishing fabrics.
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The major disadvantage of wax water repellents is poor
durability. Wax is easily abraded by mechanical action and
wax dissolves in dry cleaning fluids. It is also removed by
laundry processes
Wax Emulsion Composition
A typical wax emulsion consists
Paraffin wax as the hydrophobe
Emulsifying agent An emulsion stabilizer
Aluminum
Zirconium salt to deactivate the emulsifying agent when the fabric is
heated.
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Silicone Water Repellents
Resinous polysiloxanes, on the other hand are more resistant to
abrasion and less soluble in dry-cleaning fluids or laundry products
. Three-dimensional crosslinked polysiloxanes fill the need provided
they could be applied to fabrics.
Resinous polymer, making the fabric highly water repellent
Advantages and Disadvantages ofsilicone water repellents
Advantages
Silicone water repellents are durable to washing and dry-cleaning. Silicones are more durable than wax repellents
Less expensive than fluorochemical repellents.
Silicone finishes resist water borne stains
Fabric hand can be made soft and pliable.
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Disadvantages
Durability is brought about by the formation of a sheath of finish
around the fiber. If the sheath cracks, durability is lost.
Adsorption of hydrophilic substances found in dry cleaning andlaundry
Products also impair water repellency.
Less durable than fluorochemical finishes.
Silicones are more expensive than wax repellents
Silicones do not resist oil borne stains.
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FLUOROCHEMICAL REPELLENTS Fluorochemical repellents are unique in that they confer both oil and water
repellency to fabrics.
The ability of fluorochemicals to repel oils is related to their low surface energy
which depends on the structure of the fluorocarbon segment
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Commercial Products
Commercial fluorochemical repellents are fluorine-containing vinyl or
acrylic polymers.
The acrylate monomer will polymerize to form a high molecular
weight polymer that can be converted to an emulsion.
The emulsion dries to a continuous film.
Add-on The amount of fluorochemical needed to achieve oil repellencyis relatively low.Shows that on many fabrics.
An add-on of 0.5% is sufficient to give optimum results.
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REPELLENT FINISHING WITH FLUOROCHEMICALS
The oil and water repellent features of fluorochemical polymers lead
to finishes applicable in two consumer product areas, durablerainwear fabrics and stain/soil resistant products. For rainwear
products,
For fabrics that can be laundered or dry cleaned, stain removal is
more important than stain prevention.
Rainwear The finish is applied by padding the formulation onto fabric, drying
at 120C and curing 1-3 minutes at 150-182oC.
The fabric will give a 100 spray rating initially and an 80 rating after 5home laundering-tumble drying cycles, An 80 spray rating is expected after one dry cleaning cycle. In
addition, oil repellency rating of 5 initially and 4 after laundering or drycleaning is expected.
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Repellent Finishes
Advantages Disadvantages
Peraffin waxes Goodwater repellency,Resistant to water pressure
Low price
Little breathability
No oil repellencyNo wash fastness
Silicones Good water repellencyWater vapor permeabilitySoft handle
Good price/performance ratio
No oil repellencyNo soil repellency
Fluorocarbons Good oil & water repellencyResistance to washing & dry
cleaningSoil repellencyGood price/performance ratio
High price Value
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Nano Technology:
Nanotechnology is defined as The precise
manipulation of individual atoms and molecules to
create layer.
Nano finishing means any technology done on ananometer or (109) meter scale.
The main aim of the nano finishing is the precise
manipulation of an individual atoms and molecules to
create a structure.
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Water Repellence Easy Care-Hydrophobic Nano Finish.
Hydrophobic surfaces can be produced mainly in two ways (i) bycreating a rough structure on a hydrophobic surface (ii)by modifying a
rough surface using material with low surface free energy.
Self Cleaning EffectThis effect is known as lotus effect (fig.4).The lotus effect depends ontwo factors namely super hydrophobicity and very high water contactangle and a very low roll off angle.
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UV-protection
A thin layer of titanium dioxide is formed on the surface of the treated cotton
fabric which provides excellent UV-protection
Nano-Care
Features
Superior Stain, Water and Oil Repellency Resists Wrinkles
Breathable Fabric
Preserves Original Hand
Easy Care
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Nano-Pel
Features Superior Water and Oil Repellency
Minimize Stains
Breathable Fabric
Preserves Original Hand
Easy Care
Durable Performance
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Testing for Water Repellent Finishes:
Water Proof:A water proof fabric is one that coated or impregnated to form a
continuous barrier to the passage of water example rubber, polyurethane, PVC
or wax coating.
Shower Proof:Fabric is often achieved by coating with a thin film of a hydrophobic
compound such as silicon.
Bundesmann Water Repellency Tester:
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Technical Specifications:
Diameter oftestspecimen: 140 mm
Diameter oftest opening 100mm
Rate ofcollection of waterineach
cup
65+ 3ml/minute
Distance betweennozzletipand
specimencentre
150 cm
Speed ofrotation ofcupassembly 5rpm
Distance betweencenter of
specimenand verticalAxis ofrotation ofcupassembly
105+10 mm
Thickness of wiper blades 5.08 to5.13mm
Radius ofcontactedges of wipers 6.35mm
Loadexerted onspecimen by
wipers
400 +50mg
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SPARY RATING
Grade Description:Complete wetting of the whole of the sprayed surface.Wetting of more than half of the sprayed surface.
Wetting of the sprayed surface only at a small discrete areas.No wetting of but appearance of small drops to the spayed surface.
No wetting of and no appearance of small drops to the sprayed surface.
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