Coated Fabrics by Vignesh Dhanabalan

Coated Fabrics

By

Vignesh Dhanabalan

Vignesh Dhanabalan - [email protected]

Why Coating..?

Tension membrane

structures

Water proof fabrics

* Decoration

* Functional

Attractive Designs


Fire Hose

Different coating resins and adhesives


Polyurethanes

Polyvinylchloride

Rubber

Starch

Cellulose

Fillers

Pigments

PU coated head

caps

PVC for abrasion

resistanceNeoprene for water

proofing

Polymer Advantages Disadvantages Products

PVC

Versatile material

Good inherent FR

Good oil, solvent resistance

Heat and RF weld able for good

watertight seams

Cracks when cold

Moderate heat and age

resistance

Plasticizers migration

Tarpaulins covering,

large tents, and

architecture uses.

Seat upholstery

Lather cloths

Protective clothing

Leisure products,

banner, bunting,

PVDC

Polyvinylidene

chloride

Very good FR

Low gas permeability

Heat weld able,clear,high gloss

Hard and brittle Blends with acrylics to

improve FR in coating

PU

Polyurethane

Tough good extensibility

God weathering abrasion resistance

Moderate FR

Relatively expensive

Limited hydrolysis

resistance

Waterproof protective

clothing

Aircraft life jackets

Silicon

Odorless, inert, good resistance to

chemical and micro-organism

High tear resistance and puncture

resistance

Low toxicity, water repellant

Some breath ability

Temp service range from – 60 to 200 oC

Attracts oily soiling

Seaming is difficult due to

release properties

Expensive

Difficult to print or apply

artwork

Lightweight covering,

tarpaulins,

Sacks

FIBCs, bulk bags

Airbags

Food, medical

application

Gaskets, seats

Parachutes

Oven curtains

Natural rubber

Excellent stretch and flexibility

Working temp upto 70 oC

Many properties obtained by

blending

Moderate sunlight and

oxidative resistance

Moderate solvent and oil

resistances

Carpet backing

Tyres

Life crafts

Conveyer belts

Protective clothing

Escape churtes

Styrene butadiene

rubber

Similar to natural rubber but

somewhat better resistances to

abrasion flexing and microrg

Similar to natural rubber Carpet backing

Nitrile rubber

Good oil resistance, which increases

with acrylonitrile content. Better

resistance to sunlight and heat.

Limited fire resistances Oil resistance clothing,

belts and items

handling oily or greasy

product

Butyl rubber

Low permeability to gases, better

resistances to heat and chemical,

oxidation.

Solvent resistance limited,

FR resistances, seaming

difficult

Air cushion, pneumatic

spring, protective

clothing for chemical

and acid. Light weight

jacket, life rafts

PTFE

Excellent resistance to acid,

alkalies,chemicals,

Solvent, oil, oxidation and

weathering

Non sticks properties

Temp service upto 260 oC

Very expensive Architecture

application calendar

belts

Food and medical uses

Gaskets, seals

Pros and Cons of different coated fibers


Fabrics Pros Cons

Cotton Excellent coating adhesion

No bonding agent

Low thermal shrinkage

Low shrinkage/weight ratio

Absorbs moisture

Vulnerable to mildew rotting

,insects

Polyester Strong with HT, low shrinkage

Relative inexpensive

Resistance to mildew, rotting and insects.

Good overall properties as considered price

Low moisture absorbency

Limited resilience.

Nylon Strong with HT variant available

Good elasticity and thermal absorbancy

Resistance to mildew rotting and insects

Fabrics may sag due to moisture

absorption

Relative inexpensive

Polyethylene /

Polypropylene

Light weight

Inexpensive

Chemically inert resistance to mildew

rotting and insects.

Adhesive difficult to some

substances

Aramid High tensile strength

High melting point

Excellent strength per weight ratio

Expensive degraded by UV or

sunlight

Glass High temperature resistances

Zero moisture absorbency

Excellent UV stability

Heavy

Brittle, poor flexing properties.

Application (Methodology)


Single layer method:

In this type of coating, usually the layer, which is applied on the base fabric, is single coated. This is useful when we required a thin coating to a substrate.

Multiplayer coating:

In this type of coating, more than one layer is usually applied on single coated fabric. By using multiplayer coating method we can improve the serviceability, durability even other coated properties for fabric.

Considerations on selection of coating material / method

Number of layer

Wet layer of thickness

Viscosity

Coating accuracy require

Coating support or web

Coating speed

Methodologies

Direct Coating

Used for fabric produced from smooth continuous filament yarns Cotton is still used in some of these industrial coating applications Influenced by the blade profile and blade angle, and by the fabric tension

Spray coating

Spray foam coating is a more cost effective solution. It is sprayed onto the surface to fill small cracks and crevices; it then expands approximately 30 times its original liquid volume .

The main drawback of this method is the non-homogeneity and expensive cost for manufacturing but this can be used for specialized narrow web bonding for design complicated structures.


Back Liking Roller Techniques

Used to apply finishes or coatings of very low viscosity. Two different finishes may be applied to the same substrate at the same time.Carpets, automotive fabrics etc. can be processed.

Hot Melt Extrusion

Used for thermoplastic polymers Application of resin at faster rateUsed to produce light weight coverings or tarpaulins and sack material

Transfer Coating

Principle Mainly used for Knitted FabricDecorative or embossed designs can be obtained

Calendar Coating

Used to produce unsupported films Adapted to apply the freshly produced film Is generally uneconomical

Rotary Screen

Used for coating polymer on to fabric with add-ons Less Tension, Uniform application, Better penetrationWell suited to lightweight nonwoven fabrics and delicate films

NOVEL COATING TECHNIQUES

Electrospun CoatingMetal & Conductive Coating PVD/CVD Super Critical Fluid Coating

Testing standards

S.no Tests Standards

1 Abrasion resistance ASTM D-3389, BS 3424

2 Flexibility IS 7016, ISO5979

3 Stiffness IS 649

4 Air permeability BS 3424

5 Water vapor permeability x ASTM E 96-80

6 Water repellency Spray rating IS390, AATCC 22-1996

7 Cone test IS 7941

8 Coating adhesion BS 3424, ASTM D-751, IS 7016

9 Color fastness to dry and wet fastness BS 3424, IS 1259

11 Penetration to chemical hazard ASTM F 739-96

12 Electrical resistivity AATCC 76-1995

13 Penetration to blood borne pathogens ASTM F 1671-97b


Evaluations of Coated material

• Either increase or decrease

• Corrosive nature of materialsTensile strength

• Skin type formationShear behavior

• Necessary parameter for durability of coated film as well as composite material

Peel strength

• Structural design

• X-ray, 3d scanning, SEM analysisDimensional stability and cell structure

• DTA – Differential thermal Analyzer

• DTG – Differential thermogravimetry

• TG - Thermogravimetry

Thermal transmition

• Determines visco-elasticity of the material

Creep behavior


Application (End Use)


Breath ability

Soft to handle

Wind proof

Good insulation properties

Resistance to UV radiations

Resistance to influence of acids, alkalis, gases.

Criteria’s to meet from a coated fabric

FABRIC COATING END USE

Cotton sheeting Olearesinous compound Oilcloth, rainwear, and linoleum.

Nylon sheeting Vinyl resins Impermeable fabric for paulins & inflatedstructure

Cotton sheeting Vinyl resins Rains wear, light duty, upholstery.

Cotton sheeting Phenolic resins Rigid plastic laminates for electricalassemblies.

Cotton sheeting Melamine formaldehyde resins Rigid plastic laminates for electricalassemblies.

Cotton sheeting Rubber compound Rain coats, friction tape, gasketting, anddiaphragms.

Cotton sheeting Vinyl resins Luggages, handbags, upholster.

Cotton mele skin Vinyl resins Luggages, handbags, upholster.


Fabrics with different coating material and their end

use

Cotton dill Vinyl resins Luggages, handbags, upholster.

Duck and canvas Rubber compound Pontoons, inflatable, lifeboats.

Duck and canvas Vinyl resins Tents and awnings

Burlap and jute Rubber compound Ventilating ducting for mines and tunnels.

Knit cotton Vinyl resins Upholstery, handbags, garments.

Knit cotton Rubber compound Rubber and boots, diaphragm.

Knit and woven rayon Vinyl resins Raincoats, shower curtains, baby pants.

Non woven cotton Vinyl resins Paulins use covering, upholstery.

Glass fabric Vinyl resins Paulins and tapes.

Glass fabric Epoxy resins and polyesters ---------------------------


Cont.…..

Commercial Products using Coated fabricsVignesh Dhanabalan - [email protected]

Build Tech – Teflon Coated

material

Gelatin coated Vascular graft on (Dacron / PTFE)

Automotive Textiles – Silicon elastomer

Ethylene vinyl alcohol coated carry bags (Packtech

PTFE coated polyester needle felt filter

fabric

Detection of Coating by Infrared spectroscopy

Spectroscopy is the study of the interaction of electromagnetic radiation with matter.

Infrared radiation is absorbed by matter in the form of bands which have a discrete frequency. (1-1000 µm)

The nature of the absorption is related to the types of atoms present and their arrangement in the molecule.

The modern machines used can store, retrieve and compare spectra to enable manufactures to check quality, identity and characteristics of the polymer they use

Disadvantages: -

Is invaluable in detecting characteristic peaks to identity the differences between chemically similar hydrocarbon polymers

Also sensitive enough to show the differences between polyester and polyether urethanes.


Summary


Coating is not a new concept and it has ben in practice for many centuries.

Coating material has been more used for imparting functional value than its counter part

decoration. No material is available in nature that can satisfy the need of the hour. To

overcome these limitations we go in for coating (Multiple combination) to provide the best

possible results.

The global demand for coated fabrics ranges around 13-14B USD in 2011 and

is expected to grow at a higher pace. Indian market which has a value of 600 million USD

growing at 10-15% per annum.

There are lot many grey areas where coated fabrics are yet to fulfill. In

coming future composite material are to rule the customer world with the help of coated

fabrics

Vignesh Dhanabalan M.Tech Technical Textiles

[email protected]

mailto:[email protected]

Bibliography


Smith William.C, smart textile coating and laminates, wood head publications, ISBN 978-1-84569-379-4, 2010.

Chapman and Hall, surface coating and raw material vol 1, 1993.

Wellington Sears handbook of industrial textiles, Sabit Adanur - 1995

Bohin; Fabrice (Lyons, FR); Pouchelon; Alain (Meyzieu, FR), ‘silicon coated fabric’, U.S.Patent.No-6369184, 9 Apr 2002..

Bruchmann; Bernd (Ludwigshafen, DE); Renz; Hans (Meckenheim, DE); Mohrhardt; Gunter (Speyer, DE), ‘one component and two component polyurethane coated fabric’, U.S.Patent No-5744569, 28 apr, 1998.

Galliot.C, Luchsinger.R.H, The shear ramp: a new test method for the investigation of coated fabric shear behavior, empa - swiss federal laboratories for materials science and technology, center for synergetic structures, ueberlandstrasse 129, ch-8600 duebendorf, Switzerland.

Donald H.Backley, Elsevier Publication, 1981.

Heimann.B.Robert, Plasma spray coating, Wiley –VCH, ISBN – 3-527-29356-6, Edition 1995.

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Coated Fabrics by Vignesh Dhanabalan

Education