Selecting a polyurethane

There are many ways to formulate polyurethane, and as the formulator develops different systems using the different properties of the different raw materials, a wide range of resins to suit different applications have evolved.

The following table demonstrates the influence that different raw materials have on the end products.

TABLE OF PROPERTIES vs. RAW MATERIALS (GENERAL GUIDE ONLY)

PROPERTY GREATEST LEAST
Tensile strength Ester Ether
Tear strength Ester Low cost ether
Compression set TDI MDI
Rebound MDI ether TDI ester
Low temp properties MDI ether TDI ester
High temp properties TDI MDI
Abrasion: sliding Ester Low cost ether
Hydrolysis resistance* MDI ether TDI ester
Oil resistance Ester Ether
Heat aging Ester Low cost ether
Abrasion: impingement MDI ether Low cost ether
UV resistance Aliphatic iso Aromatic iso
Solvent resistance Ester Ether

*Polyester is made by reacting alcohol and acid together.  Water is a by-product.  Therefore, if a polyester product is exposed to a lot of water, there is a tendency for a reverse reaction to take place.  This is why the hydrolysis resistance is poor.

It is important to select the correct resin system for each application.  Your NUI representative will assist with this.

Information required when selecting a system:

  • Environment:  hydrolysis, oil, solvent resistance.
  • Heat resistance.
  • Performance required from the end product.
  • Physical properties:  tensile strength, elongation, tear and abrasion resistance.
  • UV resistance.
  • Anti-fungal or anti-bacterial properties.
  • Potlife.
  • Shore hardness.
  • Processing equipment available.
  • Cost considerations.
  • Equipment and resources available.

Discuss your choice of material with your NUI representative, who is kept up to date with new information and products.

NUI Key for coding of products:

BACK BONE POLYOLS

T = PTMEG / PTMG
G = POPG / PPG
E = ESTER
C = CAPROLACTONE
GT = PTMEG / POPG blends

TERMINATING ISOCYANATES

HOT CURES:

10 = TDI Prepolymer   (usually cured with 600M)
60 = MDI Prepolymer  (usually cured with 600D)
H = TDI Prepolymer, Hybrid  (usually cured with 600M)

For example:   Ultracast 10T90

10 = TDI
T = PTMEG
90 = Hardness 90 Shore A

COLD CURES: 

200 = Polyol component, cold cure elastomer, cured with MDI
250 = Polyol component, cold cure set ratio elastomer, cured with MDI
70 = Polyol component, elastoplastic cold cure, cured with MDI
400 = Polyol component, usually spray systems, sprayed with MDI    

OTHER CODES:

600 = Curatives e.g. 600M (MOCA / MBCA)
650 = Catalysts e.g. 650 CC
900 = Solvents e.g. 900-001
401 = polyol component for polyurea
520 = single component moisture cures
500 = various isocyanates
30 = PPDI prepolymers
150 = Additives
280 = NC Ink Flexibilisers and blocked prepolymers
300 = Polyether based cold cures
350 = polyol for elastoplastic spray and brush coat systems
450 = polyol for spray systems
480 = polyol for hydrophobic spray systems
501 = prepolymer for polyurea spray systems
521 = pigmented moisture cure coatings –MDI
522 = pigmented moisture cure coatings –TDI
523 = pigmented moisture cure coatings –HMDI
524 = moisture cure coatings –IPDI
580 = single component expansion joint systems
650 = catalysts
700 = flooring compounds
750 = polyol for brush applied waterproofing
800 = polyol for concrete primers
820 = pigment paste and dyes
850 = polyol for two component expansion joint systems
860 = polyol for polyurethane / acrylic paint blended systems
920 = dispensing machine flushing agents
930 = plasticisers



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