IMUTHANE Handling

Do’s and Don’t’s of Urethane Processing I

Step Do’s Don’t’s

Material Receipt

Check Containers for Proper LabelsCheck for Damage

Accept without InspectionAccept Damaged Goods

Material Storage

Protect Against HeatProtect Against Moisture

Expose to RainExpose to HeatLeave Bungs Loose

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)

Do’s and Don’t’s of Urethane Processing II

Step Do’s Don’t’sMeltdown Use Minimum Temperature

Control the Time Under HeatKeep Record for each Container (Time & Temperature)Use FIFO

Attempt to Speed Melting by Increasing TemperatureUse Same Oven for Curing and MeltingRely on Memory

Material Transfer

Use Closed System if PossibleProvide Local VentilationBlanket Tank and Containers with Dry Nitrogen

Pressurize DrumsBreathe Isocyanate FumesLeave Drums open to Air

Why Melt Slowly?

High temperatures = death for prepolymer molecules.

The outside of the drum can be at 100°C and the inside solid.

Heat HistoryToo 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

22-90A Heat Aging @ 70°C & 100°C

3.4

3.5

3.6

3.7

3.8

3.9

4

4.1

4.2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

%NCO

Duration of Heat Aging (Days)

%NCO of 22-90A after Heat Aging

Heat aged @ 70°C

Heat aged @ 100°C

22-90A Heat Aging @ 70°C & 100°C

0

10000

20000

30000

40000

50000

60000

70000

80000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Viscosity (cPs)

Duration of Heat Aging (Days)

Viscosity of 22-90A @ 30C after Heat Aging

Heat aged @ 70°C

Heat aged @ 100°C

22-90A Heat Aging @ 70°C & 100°C

60

65

70

75

80

85

90

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Hardness (Shore A)

Duration of Heat Aging (Days)

Hardness of 22-90A after Heat Aging

Heat aged @ 70°C

Heat aged @ 100°C

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

Moisture ContaminationMoisture 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.

Moisture Contamination – An Example IMUTHANE PST 80A (TDI polyester)

3

3.05

3.1

3.15

3.2

3.25

3.3

3.35

3.4

3.45

3.5

3.55

3.6

Fresh Water degraded

%N

CO

1. Quality Control - %NCO

Specifications

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

Fresh Water degraded

Vis

co

sit

y, c

Ps

2. Quality Control - Viscosity

Specifications

Moisture Contamination – An Example IMUTHANE PST 80A (TDI polyester)

4

4.4

4.8

5.2

5.6

6

6.4

6.8

7.2

7.6

8

8.4

Fresh Water degraded

Po

t Lif

e, m

ins

3. Processing - Pot Life

Specifications

10

20

30

40

50

60

70

10 20 30 40 50 60

Ha

rdn

es

s, S

ho

re A

Time (mins)

4. Processing - Hardness Build-Up

Fresh Water degraded

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

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)