Pros and Cons of polyurethane coating

Vignesh Dhanabalan (12mtech13)

What is polyurethane/synthesis of polyurethane Isocyanate/di-isocyantae + polyol + catalyst + surfactants +

blowing agents

One component and two component system

Isocynate -> aliphatic - > uv resistant

-> aromatic - > hydrolitic resistant

Reactors during Polymerization Types of polyols

Rigid polyurethane -> chain extender + isocyanate + high cross linking agent

Flexible polyurethanes -> longer chain extender + isocyanate + low cross linking agent

Property enhancer Thermal behavior

Compressive nature

Acoustic nature

Blowing agent Open cell structure – 3.6 to 3. 8

Closed cell structure – 6.0 to 7.14

Surfactants Hydro philicity/phobicity nature

Polyols

Polyether polyols contain the repeating ether linkage –R-O-R- and have two or more hydroxyl groups as terminal functional groups.

Water soluble polymers with a molecular weight between 200 and 14,000.

Shorter linkages Rigid polymer

Polyester polyols have repetitive ester linkage and are also called as elastomeric polyols.

Aliphatic and Aromatic polyols. Flexible polymer with better

compressive nature. Longer linkage Comparatively biodegradable.

Ether polyols

Behavior of Polyurethane (properties)

Thermal nature (-30 to 90Cº) sustain upto 250ºC , 80% at high preassure

Effect of water on thermal behavior of foams - λ = 0.58 W/(m·K)

Degradation of foam material – Damage to cell structure at cyclic loading

Compressive nature of polyurethane foam

Effect of cyclic loading – 3% energy for deformation

Crack formation – 320Kgm-3

Tensile behavior

Chemical nature

Adhesivity

Polyurethane coating and application methods

Dual nozzle spray gun Rod mayor method

Immersion method

Surface lamination

Knife coating

Floating

knife

Extrusion

Calendaring

Curtain

coating

Gurave

coating

Reverse roll

Square

Tapered

Round

J-blade

Footed j-

blade

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 materialPeel strength

• Structural design• X-ray, 3d scanning, SEM analysis

Dimensional stability and cell

structure• DTA – Differential thermal Analyzer• DTG – Differential thermogravimetry• TG - Thermogravimetry

Thermal transmition

• Determines visco-elasticity of the materialCreep behavior

Testing standardsS.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

Application of polymeric coating on end product

Acoustic insulation Metal coating Sealant

Wood laminates Filter medium

Floor polishes

Insulating tubes

ETC………….

Advantages and limitations

Multiple layer coating

Resistive to chemical and flame

High capital investment

Low maintenance and after care

Evolution of gases during synthesis

VOC

Untraped research works

To inhibit thermal insulative value to structures using it as a composite

structure.

Redesign infrastructural components with light weight polyurethane casing .

Usage of biodegradable castor based polyols for degradable polyurethanes.

Evolution of low thermal effects.

Effective waterproof breathable coatings for fabric surfaces

Reduce capital cost

Polyurethane vascular prosthesis carrying a dipyridamole is under research.

Conclusion

Polyurethane that was synthesized accidentally has found a viable replacement for lightweight high stiffness material.

Multi functional properties are able to achieve with less use of catalyst.

Their usage has been seeing the down face basically because of environmental concern over the use of fossil based raw material.

The use of natural oil for its synthesis is under going research work which has shown good results.

Bibliography Sen kumar.A, Coated textiles principle and application second edition CRC press ISBN

978-1-4200-5345-6, 2007.

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.

Maria-carmen loghin, irina ionescu, pulferia nicolaiov, ionuț dulgheriu, thermal characterization of coated fabrics, unpublished work.

http://commercialroofinglosangeles.wordpress.com/2012/02/02/coat-it.

http://www.swagathurethane.co.in/polyurethane-coating.html

http://www.foamroofing.com/aboutspf.html

W.-y. li and C.-j. li, Effect of annealing treatment on the microstructure and properties of cold-sprayed cu coating, thermal spray , internal thermal spray conference. 2005

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.

Jia.Y, Jiang.M.Z, Gong.X.L, Zhang.Z Creep of thermoplastic polyurethane reinforced with ozone functionalized carbon nanotubes, eXPRESS Polymer Letters Vol.6, No.9 (2012) 750–758.

http://www.baycoll.com/BMS/DB-SC/BMS_RSC_CAS.nsf/id/PortalEN_Properties_of_polyurethane_coatings

http://www.bayercoatings.de/BMS/DB-RSC/BMS_RSC_CAS.nsf/id/COEN_Wood

http://www.indiamart.com/acesports/sports-surfaces.html