Waterproof breathable fabric

1. Seminar Report On
“Waterproof breathable fabric”
Submitted in partial fulfilment of the
Requirements for the award of the degree of
BACHELOR OF TECHNOLOGY
in
TEXTILE CHEMISTRY
Submitted By
Vijay Prakash
(1704460060)
Textile Chemistry

2. TABLE OF CONTENTS
CHAPTER PAGE
ACKNOWLEDGMENTS………………………………………………………………………………...……. I
ABSTRACT ....................................................................................................................................... II
INTRODUCTION.............................................................................................................................. III
Types of waterproof breathable fabric:..............................................................................................IV
DENSELY WOVEN FABRIC ............................................................................................................ V
MEMBRANES ..................................................................................................................................VI
MICROPORAS MEMBRANE ..........................................................................................................VII
LAMINATE OF MERMBRANE AND OUTER FABRIC .......................................................................1
COATING..........................................................................................................................................4
VARIOUS COMMERCIAL WATER BREATHABLE FABRIC……………………………………………18
RESULTS AND DISCUSSION: .......................................................................................................38
CONCLUSION: ...............................................................................................................................81
REFRENCES: .................................................................................................................................82

3. ACKNOWLEDGEMENT
Present inspiration and motivation have always played a key role in the success of
any venture.
I offer my profound gratitude to the management of UPTTI, Kanpur. For giving
me the opportunity to do prepare the project report. I express my sincere thanks to
Dr. G. Nalankilli, Director of Uttar Pradesh Textile Technology Institute,
Kanpur.
I pay my deep senseof gratitude to Pro. ALKA ALI, UPTTIKanpur to encourage
me to the highest peak and to provide me the opportunity to prepare the project.
I feel to acknowledge my indebtedness and deep sense of gratitude to Respected
ALKA ALI whose valuable guidance and kind supervision given to me throughout
the course which shaped the present work as its show. I am immensely obliged to
my friends for their elevating inspiration, encouraging guidance and kind
supervision in the completion of my project.
Last, but not least, My Parents are also an important inspiration for me. So, with
due regards. I express my gratitude to them.
ANOOP SINGH
1704460013
Textile Chemistry
Uttar PradeshTextile Technology
Institute Kanpur, Uttar Pradesh

4. ABSTRACT
The focus of this study is on determining the optimum combination of hydrophilic
and hydrophobic components in coating material to obtain high breathability and
waterproof properties. Polyurethane binder and silicone oil were used in eight
different combinations to coat the fabric along with one sample with 100%
polyurethane binder for control. A knife-over-roll coating machine was used to
coat the fabric. The coated samples were tested by using the Sweating Guarded
Hot Plate method for breathability and the spray test and contact angle method for
waterproof properties. Results obtained from the tests showed that fabric coated
with an 80%-20% and 85%-15% polyurethane-silicone oil combination displayed
best performance in terms of waterproof and breathable properties. The research
also concludes that with a decrease in percentage of silicone in the material, there
is an increase in breathability as well as waterproof properties of fabric, and best
performance is achieved when its percentage is between 20 and 25%.

5. Introduction:
Waterproof breathable fabrics are designed for use in garments that provide
protection from the weather that is from wind, rain and loss of body heat. Clothing
that provides protection from the weather has been used for thousands of years.The
term 'breathable' implies that the fabric is actively ventilated. This is not the case.
Breathable fabrics passively allow water vapour to diffuse through them yet still
prevent the penetration of liquid water. Production of water vapour by the skin is
essential for maintenance of body temperature. The normal body core temperature
is 37C, and skin temperature is between 33 and 35C, depending on conditions. If the
core temperature goes beyond critical limits of about 24C and 45 C then death
results. The narrower limits of 34 C and 42C can cause adverse effects such as
disorientation and convulsions. If the sufferer is engaged in a hazardous pastime or
occupation then this could have disastrous consequences. During physical activity
the body provides cooling partly by producing insensible perspiration. If the water
vapour cannot escape to the surrounding atmosphere the relative humidity of the
microclimate inside the clothing increases causing a corresponding increased
thermal conductivity of the insulating air, and the clothing becomes uncomfortable.
In extreme cases hypothermia can result if the body loses heat more rapidly than it
is able to produce it, for example when physical activity has stopped, causing a
decrease in core temperature. If perspiration cannot evaporate and liquid sweat
(sensible perspiration) is produced, the body is prevented from cooling at the same
rate as heat is produced. forexample during physical activity, and hyperthermia can
result as the body core temperature increases. If the body is to remain at the
physiologically required temperature, clothing has to permit the passage of water
vapour from perspiration at the rates under the activity conditions The ability of
fabric to allow water vapour to penetrate is commonly known as breathability. This
property should more scientifically be referred to as water vapour permeability.
Waterproof breathable fabrics prevent the penetration of liquid water from outside
to inside the clothing yet permit the penetration of water vapour from inside the
clothing to the outside atmosphere.

6. 2.0.Types ofwaterproofbreathable fabric
There are several methods which can be used to obtain fabrics which are both
breathable and waterproof. These can be divided into three groups:
Densely woven fabrics
Membranes
Coatings.
2.1.1. DenselyWovenFabrics:
Probably the first effective waterproof breathable fabric was developed in the
1940s for military purposes and is known' as Ventile. Ventile fabric was carefully
engineered to make it effective1.The finest types of long staple cottons are selected
so that there are very small spaces between the fibres. The cottonis processed into
combed yarn, which is then plied. This improves regularity and ensures that the
fibres are as parallel as possible to the yarn axis, and that there are no large pores
where water can penetrate. The yarn is woven using an Oxford weave, which is a
plain weave with two threads acting together in the warp. This gives minimum
crimp in the weft, again ensuring that the fibres are as parallel as possible to the
surface of the fabric.
waterproof-breathable-fabric:
When the fabric surface is wetted by water, the cotton fibres swell transversely
reducing the size of the pores in the fabric and requiring very high pressure to cause
penetration .The fabric is thus rendered waterproof without the need for any water-
repellent finishing treatment. The military variants use thread densities as high as 98
per cm. Fabric for other applications uses much lower thread densities necessitating
a water repellent finish to achieve the waterproof properties. Densely woven fabric
can also be made from synthetic microfilament yarns. The individual filaments are
less than 10 micrometer in diameter, so that fibres with very small pores can be
engineered. Microfilaments are usually made from polyamide or polyester. The
latter is particularly useful as it has inherent water-repellent properties. The water
penetration resistance of the fabric is improved by application of silicone or
fluorocarbon finish Although fabrics made from microfilaments have a soft handle
many of them are windproof, but not truly waterproof as the synthetic filaments do
not swell when wet. The useof very fine fibres and filaments and dense construction
results in fabrics with very small pore size compared with conventional fabrics.

7. Typical pore size for a waterproof fabric is about 10 micrometer compared with 60
micrometer for conventional fabric. Ventile fabric has a pore size of about 10
micrometer when dry and 3-4 micrometer when wet2. Fabric made from
microfilaments is claimed to have up to 7000 filaments per centimetre. The military
variant of Ventile fabric has about 6000 fibres per centimetre.
2.1.2. Membranes
Membranes are extremely thin films made from polymeric material and engineered
in such a way that they have a very high resistance to liquid water penetration, yet
allow the passageofwater vapour. A typical membrane is only about10 micrometer
thick and, therefore, is laminated to a conventional textile fabric to provide the
necessary mechanical strength. They are of two types, microporous and hydrophilic
2.1.2.1. Microporous Membrane
The first and probably the best known microporous membrane developed and
introduced in 1976 byW.Gore,is known as Gore-Tex.This is a thin film of expanded
polytetrafluoroethylene (PTFE)polymer claimed to contain 1.4 billion tiny holes per
squaremeter.The holes are much smaller than the smallest raindrop (2-3 micrometer
compared with 100 micrometer)3 yet very much larger than a water vapour
molecule. Other manufacturers make similar membranes based on microporous
polyvinylidene fluorIde (PVDF) cast directly on to the fabric4. The hydrophobic
nature of the polymer and small poresize requires very high pressure to cause water
penetration. Contamination of the membrane by various materials including body
oils, particulate dirt, pesticide residues, insect repellents, sun tan lotion, salt and
residual detergent and surfactants used in cleaning' have been suspected ofreducing
the waterproofing and permeability to water vapour ofthe membrane. Forthis reason
microporous membranes usually have a layer of hydrophilic polyurethane to reduce
the effects of contamination5.
2.1.2.2. Hydrophilic Membranes

8. Hydrophilic membranes are very thin films of chemically modified polyester or
polyurethane containing no holes which, therefore, are sometimes referred to as non-
poromeric. Water vapour from perspiration is able to diffuse through the membrane
in relatively large quantities. The polyester or polyurethane polymer is modified by
incorporating up to 40% by weight of poly (ethylene oxide).
2.The poly (ethylene oxide) constitutes the hydrophilic part of the membrane by
forming part of the amorphous regions of the polyurethane polymer system. It has a
low energy affinity for water molecules which is essential for rapid diffusion of
water vapour6. These amorphous regions are described as acting like intermolecular
'pores' allowing water vapour molecules to pass through but preventing the
penetration of liquid water owing to the solid nature of the membrane
Methods of Incorporation
Membranes have to be incorporated into textile products in such a way as to
maximize the high tech function without adversely affecting the classical textile
properties of handle , drape and visual impression3.There are four main methods of
incorporating membranes into textile products.Themethod employed depends upon
cost,required function and processing conditions3:
a) Laminate of membrane and outer fabric :
The membrane is laminated to the underside of the outer fabric to producea to layer
system.This method has the disadvantage of producing a rustling, paper like handle
with reduced aesthetic appeal but have advantage of very effective protective
properties of wind resistance and water proofing.This method is mainly used for
protective clothing
b) Liner or insert processing:

9. The membrane is laminated to a light weight knitted material or web.The pieces are
cut to shape from this material, sewn together and the seams rendered waterproof
with special sealing tape. This structure is then loosely inserted between tite outer
fabric and the liner. The three materials (outer, laminate and lining) are joined
together by concealed stitch seams. If high thermal insulation is required, then the
lightweight support for the membrane is replaced by a cotton, wool or wadding
fabric. This method has the advantage of giving soft handle and good drape. The
outer fabric can also be modified to suit fashion demands.
c) Laminate of membrane and lining fabric:
The laminate is attached to the right side of the lining material. The functional layer
is incorporated into the garment as a separate layer independent of the outer fabric.
This method has the advantage that the fashion aspects can be maximized.
d) Laminate of outer fabric, membrane and lining:
This produces a three-layer system,which gives a less attractive handle and drape
than the other methods and, therefore, is not commonly
2.1.3. Coatings
These consist of a layer of polymeric material applied to one surface of the fabric.
Polyurethane is used as the' coating material. Like membranes, the coatings are of
two types; micro porous and hydrophilic. These coatings are much thicker than
membranes. Contains very fine interconnected channels, much smaller than the
finest raindrop but much larger than a water-vapour molecule
2.1.3.1. Micro Porous Coatings
Wet Coagulation

10. Polyurethane polymer is dissolved in the organic solvent dimethyl formamide to
produceasolution insoluble in water. This is then coated on to the fabric. The coated
fabric is passed through a conditioning chamber containing water vapour. As the
organic solvent is miscible with water, it is diluted and solid polyurethane
precipitates. The fabric is then washed to remove the solvent, which leaves behind
pores in the coating. Finally the coated fabric is mangled and dried. This method is
not very popular as it requires high capital costfor machines and solvent recovery is
expensive.
Thermocoagulation
Polyurethane is dissolved in an organic solvent and the resulting solution mixed with
water to produce an emulsion. The emulsion 'paste' is coated on to one side of the
fabric. The coated fabric then goes through a two-stage drying process. The first
stage employs a low temperature to remove the organic solvent, precipitating the
polyurethane. The coating is now a mixture of solid polyurethane and water. The
second stage employs a higher temperature to evaporate the water leaving behind
pores in the coating.
Foam Coating
A mixture of polyurethane and polyurethane/polyacrylic acid esters are dispersed in
water and then foamed. The foam is stabilised with the aid of additives. The foam is
then coated on to one side of the fabric. The coated fabric is dried to form a micro
porous coating. It is important that the foam is opencell to allow penetration ofwater
vapour but with small enough cells to prevent liquid water penetration. The fabric is
finally calendered under low pressure to compress the coating. As the foam cells are
relatively large, a fluorocarbon polymer water-repellent finish is applied to improve
the water-resistant properties. This type of coating production is environmentally
friendly as no organic solvents are used.

11. Hydrophilic Coatings
Hydrophilic coatings5 use the same basic water vapour permeability mechanism as
the hydrophilic membranes. The difference between microporous materials and
hydrophilic materials is that with the former, water vapour passes through the
permanent air-permeable structure whereas the latter transmit vapour bya molecular
mechanism involving adsorption-diffusion and desorption. These coatings are all
based on polyurethane, which has been chemically modified by incorporating
polyvinyl alcohols and polyethylene oxides. Thesehave a chemical affinity for water
vapour allowing the diffusion of water vapour through the amorphous regions ofthe
polymer.The balance between hydrophilic and hydrophobic" components of the
polymer system has to be optimised to give acceptable vapour permeability,
flexibility, durability and insolubility in water and dry cleaning solvents.
waterproof-breathable-fabric
Swelling of the membrane is encouraged to assist water vapour diffusion yet it also
has to be restricted to prevent dissolution or breakdown in water or in the other
solvents with which the polymer is likely to comeinto contact. Poly (ether-urethane)
coatings and membranes have excellent integrity. This canbe conferred in two ways:
 by a high degree of hydrogen bonding, principally between polar groups in
the hydrophobic segments of adjacent polymer chains
.
 by forming covalent crosslinks between adjacent polymer chains. The
effective length and density of the crosslinks are variables affecting polymer
swelling and thus vapour permeability.
Methods of Applying Coatings
The conventional method of applying coatings to fabric is to use direct application
using the knife over roller technique3. The fabric is passed over a roller and liquid
coating is poured over it. Excess liquid is held back by a 'doctor blade' set close to

12. the surface of the fabric. The thickness of the coating is determined by the size of
the gap between the blade and the surface of the fabric. The coated fabric is passed
through a dryer to solidify the coating. Sometimes the coating is built up in several
layers by a number of applications. In order to achieve thinner coatings and,
therefore, more flexible fabric and to apply coating to warp knitted, nonwoven, open
weave and elastic fabric, transfer coating is used. The liquid coating is first applied
to a silicone release paper using the knife over roller technique. This is then passed
through an oven to solidify the coating. A second coating is then applied and the
textile fabric immediately applied to this. The second coating, therefore, acts as an
adhesive. This assembly is passed through an oven to solidify the adhesive layer.
The coated fabric is stripped from the release paper, which can be reused.
3.0 Various Commercial Water Breathable Fabric
Breathable Membranes
All breathable microporous membranes comprise an extremely thin man-made film
whose physical structure contains microscopic pores that are large enough for water
vapour (perspiration) to pass through but small enough not to let water droplets
through. Thus the membrane is breathable, waterproof and windproof. Modern
microporous membranes are usually laminated to a face fabric, and available in two
and three layer versions.
Gore-Tex
Gore-Tex is a unique wafer thin microporous membrane, which contains over 9
million pores persquareinch. Each poreis 20,000 times smaller than a water droplet,
yet some 700 times bigger than a moisture vapour molecule. This gives the fabric
the excellent levels of waterproofness and breathability that the brand is famous for.

13. Gore-Tex is a bi-component membrane, meaning that it is made up oftwo parts. The
main part is made from expanded polytetrafluoroethylene. This is then combined
with an oleophobic (oil hating) layer that protects the membrane from the natural
oils that the human body emits, insect repellents, cosmetics etc. The outer face of
the Gore-Texfabric is coated with a hydrophobic DWR (Durable Water Repellency)
treatment which encourages surface water to bead up and run off, improving the wet
weather performance of the garment and promoting breathability by preventing
wetting-out of the outer face. There are a number of different Gore-Tex
constructions currently used within the industry:
Classic 2-Layer
Provides soft, versatile weather protection and is good forend uses such as walking,
streetwear, golf and skiing. Made by laminating a nylon or polyester face fabric to
the Gore-Tex membrane and then hanging a mesh lining just inside the laminate.
Classic 3-Layer
Designed for ultimate durability in rugged use applications in tough weather
conditions such as high altitude mountaineering. Made by again laminating a face
fabric (usually nylon) to the Gore-Tex membrane, an inner protective mesh scrim is
then laminated to the other side of the membrane, giving better durability.
Paclite
Lightweight and more packable than either two- or three-layer garments, designed
for ultra-light mountaineering or other fast-moving sports. As with two-layer
garments, the face fabric is bonded to the Gore-Tex membrane, but unlike either of
the other constructions, abrasion resistant raised nubs (or dots) protect the
membrane. This means that as there is less between you and the membrane,
breathability is increased.

14. XCR
Standing for extended Comfort Range, XCR is the new product from Gore-Tex,
which by using new membrane technology and new lamination techniques offers
25% more breathability than classic Gore-Texgarments. Designed formountaineers,
backpackers, snowboarders, backcountry skiers and other outdoor enthusiasts who
value performance and demand the most from their gear. Available in both two- and
three-layer construction.
Hydro Dry P3 (Spray way)
The top fabric in the Hydrodry range from Sprayway, P3 has a hydrostatic head of
10,000mm. It is waterproof and has a good level of breathability. Again developed
from a hydrophilic laminate, Hydrodry P3 is available in both 2-layer and 3-layer
constructions. Hydrodry P3 provides Sprayway customers with a technical
alternative to Gore-Tex in the same way that Drilite Extreme does for Mountain
Equipment.
Breathable Coatings
All coatings are created by spreading a thin layer of resin directly onto to the inside
face ofthe chosenfabric. Two distinct types of breathable coating exist: microporous
and hydrophilic. A microporous coating works on the same principle as a
microporous membrane, the pores in the coating being large enough to let water
vapour pass through but small enough to keep water droplets out. Hydrophilic
coatings rely on the chemical and molecular properties of water molecules. The heat
that the bodygenerates inside the garment drives water vapour (perspiration) down
the polymer chains found in the coating to the external face, the water vapourmoving
from molecule to molecule rather than freely through a physical hole orpore. As the
bodyproducesmoremoisture and the fabric gets wetter, the chains naturally increase
in size, allowing even more moisture movement. In use, both types of coatings are

15. effective, with the overall performance of any garment being determined by a
combination offactors such as the choice offace fabric, use of a separate lining, and
the general design, cut and finish of the garment.
Triple Point Ceramic (Lowe Alpine)
TriplePoint Ceramic is a unique multi-layer microporous coating which is
waterproof, windproof and breathable. It differs from other treatments in that the
manufacturing process involves multiple coatings and the introduction of ceramic
particles, which are impregnated into the coating under high pressure.
This has the effect ofcreating microscopic holes around each particle. Thesecavities
are large enough to permit the passage of water vapour to the outside face but small
enough to prevent liquid water from moving the other way. Since the TriplePoint
Ceramic coating is physically anchored to the fabric it wont de-laminate or become
damaged. This construction is what makes the fabric inherently windproof as well
as highly breathable and waterproof. A special Dry Yarn technology DWR treatment
is also applied to the coated fabrics outer face to significantly improve wet weather
performance and beading, (this can be re-generated simply by exposing the garment
to a direct heat source i.e. medium heat iron or tumble drier). There are currently
two constructions of Triplepoint Ceramic used in garment production.
Standard
The fabric is constructed and coated as described above and a free hanging Dryflo
mesh lining is then added to protectthe coating, and to help disperse any condensed
water droplets on the inner face of the garment.
Direct Lined
Triplepoint Ceramic Direct Lined is a new fabric combination for the Alpine Pro
range . Unlike the standard construction, a fixed lining is applied directly to the
Triplepoint Ceramic coating. This gives better performance when combined with a
high spec. face fabric.

16. Triple Point (Lowe Alpine)
A multi-layer non-ceramic coating which is lighter than Triple Point Ceramic and
therefore better suited to general walking/outdoor activities rather than more
demanding outdoor sports. The outer face of the fabric has a standard DWR
treatment applied to it to enhance wet weather performance.
Hydrodry P2 (Sprayway)
A more basic version of Sprayways Hydrodry P3, Hydrodry P2 is a mixture of
hydrophilic coatings and laminates rather than a laminate outright. With a lower
hydrostatic head (5,000mm) than P3 and a slightly lower degree of breathability,
Hydrodry P2 is pitched at the more general walking market. Available only in the
equivalent ofa two-layer construction, HydrodryP2 is a good competitorto standard
Triplepoint and Aquadry.
Waterproof & Showerproof Breathable Fabrics
This chemical process is helped by a pressure difference, which drives the water
vapourfrom the high pressureinside the clothing system, to the low pressureoutside.
While not as efficient or as durable as GORE-TEX fabric, hydrophilic fabrics do
offer a lower price point. Breathable waterproof fabrics have taped seams, thus
making them fully waterproof for coastal, inshore and dinghy sailing, as well as
onshore use.

17. CONCLUSION
Water proofbreathable fabric are designed to provide protection from the wind, rain
and loss of body heat. The breathable fabric passively allows the water vapour and
prevents the penetration ofliquid water forcomfortclothing. Thebreathable are very
much better than fabric coated with conventional water proofmaterials, which have
a higher resistance to vapour transport than ordinary woven and knitted apparel
fabric. The water proofbreathable fabric continues to breathe under rainy condition.
However, the breathability of most of them ultimately ceases after long exposure to
prolonged severe rainy condition. The water proof breathable fabric is highly
breathable, too, keeping you dry and comfortable whatever your activity.
REFERENCES
 Ventile Technical Literature, Harris Watson Investments Ltd, Talbot Mill,
Froom Street, England.
 Gr Lomax Textiles, 1991, No:4, 12.
 W Mayer, U Mohr And M Schuierer,Int. Textile Bull, 1989,No:2,18.
 Anon, Design News, 1988,44,No:13(July )48.
 J Lomax,Coated Fabrics,1990 20(October)88.
 W O Lotens, What Breathability Do You Need Symposium, June 1991
 David A Holmes, Water Proof Breathable Fabrics.