Coating of Textiles

Coating of technical textiles Description of coating application to produce Technical Textiles Dr Muhammad Mushtaq Mangat www.mushtaqmangat.org

Chemistry of coated textiles

  Spread of a viscose material to develop certain properties

  Viscose material is coated and dried/cured for long lasting attachment

  Coating is limited to linear to linear polymers, on drying they are converted into hard film

  All thermoplastic polymers having long chain long chain linear molecules

  Few have the ability to crosslink

Polyvinyl chloride (PVC) Made by free radical polymerization of vinyl chloride It is hard rigid solid

PVC

  Hard rigid solid,

  Can absorb many plasticisers

  For example

cyclohexylisooctylphthalate

  Such addition creates new avenues of its application

  This unique property increase its worth

PVC Coated tarupaulin Gives hardness and used for protection

PVC coated PET

  Used as Technical Textiles

  More rigid and hard still flexible able to adapt various shapes

Polytetrafluoroethylene (PTFE)[1]

  PVDC is very similar to PVC

  Made by using emulsion polymerisation of vinylidene chloride

  Low gas permeability

  More expensive than PVC

  Give better flame resistance due to 2 molecules of chlorine

Polytetrafluoroethylene (PTFE)

  Developed by Du Pont in 1941Made by polymerization of tetrafluoroethylene

  Used as protective material from sun light

PTFE applications   Water and repellant

  Highly thermal resistance (250C)

  Inert to most common solvents and chemicals

  Can be degraded by strong

  Expensive comparatively

Rubber [1]

  Natural rubber a linear polymer of polyisoprene

  Obtained from the sap of many plants

  It can be used directly for coating

  Natural polymer contains unsaturated double bonds along the polymer chain

Rubber Modification [1]

  It can be crosslinked with sulphur

  It is called vulcanisation,

  Gives abrasion-resistant films or hard ebony-like structures.

  Flexibility depends upon the amount of crosslinking

  Prone to oxidation and ozone attack

http://www.archerrubber.com/

Styrene–Butadiene Rubber (SBR) [1]

  Is made by emulsion polymerisation of styrene and butadiene

  Application is similar to natural rubber

  Less resilient than natural

  Superior weatherability and ozone resistance

  More than 50% of all rubber used is SBR

Application of SBR coated cloth

Nitrile rubber [1]

  Nitrile rubbers are copolymers of acrylonitrile and butadiene

  Highly oil resistance,

  Excellent tensile strength and resistance to abrasion

  Used for fuel tanks, not good for tires

Butyl rubber [1]

  It I copolymers of isobutylene and isoprene

  Developed by BASF in 1931

  Used as fuel additive, explosive, sports items, chew gum, tires, coating material

Many more coating material

  Chlorosulphonated polyethylene (Hypalon)

  Silicone rubbers

  Polyurethanes

  Glass wool coating

  Teflon

  Wax

  Aluminized kevlar

  Elastomer coating

  High temperature coating

  And many more…

Coating techniques [1]

  Lick role

  Fabric is passed over a roller, which is dipped in solution

Knife coating

  fixed knife is used to spread solution

  Thickness depends upon the gap between knife and fabric

  • knife on air

  • knife over table

  • knife over roller

  • knife over rubber blanket.

Metalorganic vapour phase epitaxy

  MOVPE is a process in which vapors of chemicals are deposited on the surface of fabric

  Quite complex process

  semiconductor multilayer structures

[http://en.wikipedia.org/wiki/Coating]

Electrostatic spray assisted vapour deposition (ESAVD)

  It is used to deposit thin and thick layers on any substance

Electrostating spraying technique is used

  Chemical reaction occurs during spraying

  Following products can be made:   Thermal barrier   Protection of photovoltaic panels   Electronic components   Biomedical coatings   Glass coatings (such as self cleaning)   Corrosion protection coatings


Physical vapor deposition

Cathodic arc deposition

  Electron beam physical vapor deposition (EBPVD)

  Ion plating

  Ion beam assisted deposition (IBAD)

  Magnetron sputtering

  Pulsed laser deposition

  Sputter deposition

  Vacuum deposition

  Vacuum evaporation, evaporation (deposition)


Chemical and electrochemical techniques

Anodising

  Conversion coating

  Anodizing

  Chromate conversion coating

  Plasma electrolytic oxidation

  Phosphate (coating)

  Ion beam mixing

  Pickled and oiled, a type of plate steel coating

  Plating

Electroless plating

  Electroplating

  Sol-gel


Optical coatings

  Antireflection coating, to reduce reflection

  A mirror coating to enhance it


Others   Dip-coating

Epitaxy (vapor phase, liquid phase)

  Vitreous enamel

  Paint

  Enamel paint

  Silicate mineral paint

  Polymer coatings, such as Teflon

  Powder coating or Powder slurry coating

  Fusion bonded epoxy coating (FBE coating)

  Molecular beam epitaxy

Sheradizing

  Spin coating

  Paper coating

  Industrial coating

  [http://en.wikipedia.org/wiki/Coating]

Roll-to-roll coatings

  Air knife coating

Anilox coater

  Curtain Coating

  Single and Multilayer Slide Coating

Flexo coater

  Gap Coating

  Gravure coating

  Hot Melt coating

  Immersion (dip) coating


  Knife-over-roll coating

  Metering rod (Meyer bar) coating

  Reverse Roll coating

  Roller coater

  Rotary screen

  Silk Screen coater

  Slot Die (Extrusion) coating


Spraying

  High velocity oxygen fuel (HVOF)

  Plasma spraying

  Thermal spraying

  Plasma transferred wire arc thermal spraying

References

  [1]Hall, M.E., Coating of technical textiles, in Handbook of Technical Textiles A.R. Horrocks, Anand, S. C., Editor 2000, Woodhead Publishing Ltd Cambridge.

Coating of Textiles

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