Polyurethane By. Muhammad . shafiq randhawa
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Polyurethanes are polymers formed by reacting di- or polyisocyanates with polyols. Dr. Otto Von Bayer discovered polyurethanes in 1937 while attempting to reduce natural rubber usage. There are several types including rigid and flexible foams, coatings, adhesives, sealants, elastomers, thermoplastic polyurethane and reaction injection molding. Polyurethanes consist of polyol monomers reacted with isocyanate monomers like MDI and TDI. The global polyurethane industry was worth $33 billion in 2010 and is expected to reach $55.5 billion by 2016. Polyurethanes are used in applications like insulation, appliances, shoes, pipes and
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Polyurethane By. Muhammad . shafiq randhawa
- 2. Polyurethanes Muhammad Shafiq Randhawa Technical Consultant Polyurethane Emailmsrandhawa87@hotmail.com Cell #00923334114187 Skyep=taha.shafiq87
- 4. History of Polyurethanes • Dr. Otto Von Bayer (1937) •IG Farben Industries •Rigid and flexible foams •TDI and polyols •Attempts to reduce natural rubber use
- 5. What are Polyurethanes? •Polyurethane •Polyurethane polymers are traditionally and most commonly formed by reacting a di- or polyisocyanate with apolyol. Both the isocyanates and polyols used to make polyurethanes contain on average two or more functional groups per molecule.
- 6. •Types of polyurethane •1.Flexible Polyurethane Foam •2.Rigid Polyurethane Foam •3.Coating,Adhesives,Sealants and Elastomers(CASE) •4.Thermoplastic polyurethane (TPU) •5.Reaction Injection Molding (PIM) •6.Binders •7.Waterborne Polyurethane Dispersions (PUDs)
- 8. Polyurethane Monomers • Polyurethanes consist of different block co-polymers • MDI- 4 4'-diphenylmethane diisocyanate • TDI- Toluene-2,4-diisocyanate
- 9. Polyurethane Monomers Polyols- hydroxy terminated polyether, polyester, polyolefins, and glycols
- 10. Polyurethane Reactions •Multiple types of reactions make up different end products of polyurethanes •Polyurea reactions are important for spandex production
- 13. Raw Materials
- 14. Components of Polyurethanes • Isocyanates • Polyol • Catalysts • Silicon surfactant • Fire retardant • blowing agent
- 15. Isocyanates; Different Isocyanates are used for the synthesies of polyurethane. Toluene diisocyanate (TDI) was the first mass produced isocyanate. It was used for rigid and flexible products before the development of Methyl phenyl diisocyanate (MDI) in the early 1960s. TDI is still used in most flexible foam and many elastomers and coatings. The TDI production process yields two difunctional isomers
- 16. . The series of multifunctional aromatic or aliphatic isocyanates are used in polyurethane foams. The detail information about synthesis and reactions of isocyanates can be studied in the literature. Polyurethane is commercially produced by the phosgenation of amines. The solution of amine and phosgene are mixed to form a slury of amine hydrochloride and carbamic chloride then by heating the amine salts react with excess phosgene.
- 19. Parameter Value Colour Dark brown Viscosity (CPS) 170-250 Specific Gravity at 25 degree centigeade 1.24 NCO content 32 Specification of Crude MDI
- 20. Molecular Weight 174.163 Density (g. per cm3) @20°C (68°F) 1.21 Viscosity (cs) @100°C (212°F) 0.8 Freezing/Melting Point Range T100 (°C) 21.5-22.0 Freezing Point 2,4-isomer (°C) 15.0 Boiling Point @10mm Hg (°C) 121 Flash Point, COC (°C) 132 Acidity, as HCI (%) T100 <0.0130 Specification of TDI
- 21. Polyols During the initial development of polyurethanes, polyesters were the most commonly used type of Polyols. Since unsaturated polyesters were found unstable for use in polyurethanes, completely saturated polyesters containing terminal hydroxyl groups rather than carboxyl groups are used many Polyols are available to the polyurethane formulator. The size, functionality, and starting materials determine the properties of the final product.
- 22. Rigid polyurethanes are formed by low molecular weight polyol. Flexible polyurethane are make from the higher molecular weight polyols, castor oil, trihydroxy fatty triglyceride, is an example of naturally occurring polyol. Polyester polyols are prepared by step growth or condensation polymerization. Formation of polyester chains is a random process and leads to broad distribution of molecular weights. Bifunctional monomer make the linear polymers.
- 23. Adipic acid used where flexibility is required, The Phthalic anhydride is used for those requiring rigidity, Dioles include ethylene glycol, 1.4 butandiol. And 1,6- hexandiol The polymerization has the characterstics of a chain reaction, whose chemistry is presented by initation, propagation and termination steps. Propylene oxide (PO) and ethylene oxide(EO) , are low price epoxides produce by the oxidation of proplylene and ethylene.
- 24. Polyols •Polyols are the major component of rigid polyurethane. Rigid polyurethane foam can be manufactured by standard polyether base and polyester base polyol.
- 25. Type of PU average molecular weight OH no(mg KOH/gram) Average functionalit y Viscosity at 25 degree centigrate (CPS) Acid number Density(gm/cm) Rigid foam 930 350-390 6.2 1500- 3000 1.0 1.1 Shoe sole 2000 58-62 2.1 700-1000 0.4 1.15 Elastomers 2000 50-58 2 500-800 1 1.17 Soft coating 2750 38-45 2 700-800 1 1.12 Hard coating 2450 250-270 11.3 17000 4 1.24 Flexible foam 2400 57-63 2.7 1000- 1200 1.3 1.15
- 27. Catalysts Catalyst is the important additive. It is control the reaction rate and also control the balance between polyol and isocyante reactions. and blowing in order to attain the desired foam properties. Amine and Tin are two good catalyst used. Formation of transient complexes between polyol and isocyanate are formed due to catalyst.
- 28. Tertiary amines can catalyze both in gelling and blowing reaction and are usually called the blowing catalysts, Reaction rate of both gelling and blowing process depend on catalyst structure.Amine catalyst are control the both these parameter. Tin catalyst are more reactive and use in less quantity but it is use for gelling reaction, so it is called the gelling catalyst. .
- 29. Surfactant •It is important additive in polyurethanes to get homogenous foam with low density, •Surfactant help in good mixing during foaming.it can prevent bobbles from collapse and stabilize the cell structure. Branching chains can be introduced to either silicone or polyether and different end group can be cooed in to chain end.
- 30. Blowing agent Different blowing agents are used to form gas bubbles in the reaction mixture Firstly water was used as a blowing agent then it was rejected due to high boiling point and open cell foam is produced which was not good for insulation. In insulation we need low thermal conductivity material but the polyurethane which is manufactured by water has high thermal conductivity. Now CFCs, HCFCs, Pentanes, HFCs are use as blowing agent in rigid PU foam these gases are responsible for excellent insulation properties
- 31. CFCs gases were phased out due to environmental problems. In japan & Europe CFCs-11 was substituted by HCFCs 141b are Pentanes. middle East Asia and Africa CFCs-11 is still used.
- 32. Blowing agent name Molecular weight gm/mole Boiling point In centigrade Liquid Density at 20 degree C Ozone depletion potential CFC-11 137.4 23.8 1.49 1 HCFC-141b 116.9 32.2 1.24 0.11 HCFC-22 86.5 -40.6 1.21 0.055 HCFC-142b 100.5 -9.8 1.10 0.065 Physical properties of different blowing agents
- 33. Breakdown of the PU Industry
- 34. Economics •The PU industry was estimated to produce 13.65 million tons of plastic in 2010 and is expected to grow to 17.95 million tons by 2016 •The PU industry is expected to grow from $33 billion in 2010 to $55.5 billion in 2016.
- 36. Rigid PU processing machines 1) Spray foam machine
- 37. 2) Discontinuous PU panel
- 38. 3) Continuous PU panel
- 39. Shoe Grade PU
- 40. Flexible PU
- 43. Wall insulation
- 46. PU shoes