Low fogging HR foams (TDI)

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HR foams can significantly contribute to fogging of windshields in cars. The use of low volatility components such as surfactants, catalysts is important to reduce fogging. Either high molecular weight additives or additives with functional groups can be used to achieve no-fogging.
Increase in the crosslinking density of the urea hard segment is important to improvement in recovery and good compression set. Either diethanolamine or polyfunctional isocyanates can be used to increase crosslinking. Increasing the crosslinking density of the soft phase (higher functional polyols) will reduce the elongation. The resulting increase in chain entanglements reduces the mobility and increases the recovery time.
For increased in rigidity of these foams higher density foams using MDI as a diisocyanate have been developed.
Formulation HR Foam Carbon dioxide blown Fogging Amine Non-fogging Amine

Polyether styrene modified OH # 30

100

100

Diethanolamine, CAS # 111-42-2

1.6

1.6

Low fogging silicone surfactant

1

1

Water

3.2

3.2

Triethylenediamine 33 %, CAS # 280-57-9

0.24

Hydroxypropylimidazole, CAS # 37788-55-9

0.35

Bis(dimethylamino)ether formic acid, CAS # 51390-19-3

0.24

Bis(dimethylamino) 2-hydroxpropanol, CAS # 5966-51-8

0.40

TDI 80,  80 % 2,4-TDI;  20 % 2,6-TDI, CAS # 26471-62-5

40.7

40.7

Isocyanate index

105

105

Test results of machine prepared foam (test methods) (Conversion factors)

Overall density kg/m ( lb/ft3),  (1 kg/m = 0.0624 lb/ft3 )

43.6(2.72)

43.7(2.73)

Core density kg/m3

40.9(2.55)

39.7(2.45)

SAG factor

2.7

2.7

CLD 40*

4.2

4.5

CLD at 40 density

4

4.6

Compression set 50 %

4

4

Compression set 70 %

8

HACS %

13

35

Tear strenght N/m

245

220

Tensile strength kPa  (1 kPa = 0.145 PSI)

165

150

Resilience

64

65

Air flow

103

103

Fogging

Silicone ppm

400

350

Amine ppm

300

<5

*CLD 40 corrected for foam density using formula CLD1 = CLD2*(r1/r2)2

Last edited on:

November 16, 2006

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