1. IMUTHANE Handling

2. Do’s and Don’t’s of Urethane Processing I
Step
Do’s
Don’t’s
Material Receipt
Check Containers for Proper Labels
Check for Damage
Accept without Inspection
Accept Damaged Goods
Material Storage
Protect Against Heat
Protect Against Moisture
Expose to Rain
Expose to Heat
Leave Bungs Loose
Keep closed and under dry nitrogen
Shelf life is generally 3 years for prepolymers if unopened and stored correctly

3. Common Manufacturing Problems Caused by Moisture or Heat History
Bubbles
Slow hardness build-up → long demold time
Low hardness
Incorrect physical / dynamic properties
Unusual appearance (change in clarity)

4. Do’s and Don’t’s of Urethane Processing II
Step
Do’s
Don’t’s
Meltdown
Use Minimum Temperature
Control the Time Under Heat
Keep Record for each Container (Time & Temperature)
Use FIFO
Attempt to Speed Melting by Increasing Temperature
Use Same Oven for Curing and Melting
Rely on Memory
Material Transfer
Use Closed System if Possible
Provide Local Ventilation
Blanket Tank and Containers with Dry Nitrogen
Pressurize Drums
Breathe Isocyanate Fumes
Leave Drums open to Air
Why is meltdown required?
Ethers (L100A, EP1251/8A) tend to be highly viscous liquids or solid at room temperature
Esters (LF1800A, LF1700A) tend to be waxy solids at room temperature
Need to melt entire contents of drum/pail before use

5. Why Melt Slowly? High temperatures = death for prepolymer molecules.
The outside of the drum can be at 100°C and the inside solid.

6. Heat History Too much heat on prepolymer before use
Happens during storage, melting, and in processing tank. Repeated heating of the same container causes the worst problems.
Gives inferior product (low hardness and other properties).
Use lowest possible temperatures and times.
Lower temperature and longer time is better than higher temperature for shorter time.
Melt containers of solid prepolymers completely before use.
Keep records

7. 22-90A Heat Aging @ 70°C & 100°C %NCO of 22-90A after Heat Aging O C N
3.4
3.5
3.6
3.7
3.8
3.9 4
4.1
4.2 1 2 3 5 6 7 8 9 10 11 12 13 14 % N C O
Duration of Heat Aging (Days)
%NCO of 22-90A after Heat Aging
Heat 70
Heat 100

8. 22-90A Heat Aging @ 70°C & 100°C Viscosity of 22-90A @ 30
10000
20000
30000
40000
50000
60000
70000
80000 1 2 3 4 5 6 7 8 9 10 11 12 13 14 V i s c o t y ( P )
Duration of Heat Aging (Days)
Viscosity of 30
C after Heat Aging
Heat 70 C
Heat 100

9. 22-90A Heat Aging @ 70°C & 100°C Hardness of 22-90A after Heat Aging )60 65 70 75 80 85 90 1 2 3 4 5 6 7 8 9 10 11 12 13 14 H a r d n e s ( S h o A )
Duration of Heat Aging (Days)
Hardness of 22-90A after Heat Aging
Heat 70 C
Heat 100

10. Slow Hardness Build-Up
Slow hardness build-up can be caused by Heat History of prepolymer, but keep in mind there are other potential causes:
Material mixed off-ratio
Wrong catalyst / level
Mold / Material Temperature too Low

11. Moisture Contamination
Moisture from air gets into Prepolymer, Curative or Additives.
Moisture reacts with the NCO group, forming CO2 (carbon dioxide) which generates bubbles.
Prevention:
Keep containers closed and under nitrogen;
Avoid paper containers and wooden stirrers;
Check moisture content of additives;
Use closed system when possible;
Microwave heating minimizes heat and air exposure.

12. Moisture Contamination – An Example
IMUTHANE PST 80A (TDI polyester)
Sample analysed fresh, and after 6 months in a can with exposure to moisture in air in headspace.
¼ inch of gel formed on surface.
Gel removed and remaining prepolymer analysed.
Material still within both specifications

13. Moisture Contamination – An Example
IMUTHANE PST 80A (TDI polyester)
Sample analysed fresh, and after 6 months in a can with exposure to moisture in air in headspace.
¼ inch of gel formed on surface.
Gel removed and remaining prepolymer analysed.

14. Moisture Contamination – How to Avoid
When opening drums / pails to remove material, close them again as soon as possible
Use dry nitrogen purge whenever closing containers
Do not use wooden stirrers or paper cups
Avoid humid atmospheres wherever possible

15. Bubbles
Bubbles can be caused by Moisture Contamination, but keep in mind there are other potential causes:
Incomplete Degassing
Pouring Technique
Solvent Leak (Machine Processing)