1
High rate of occlusion
Polyether polyol: high proportion of ethylene oxide, high activity, mostly occurring in the replacement of polyether polyol with different activity.
Process formula: high amount of stannous octanoate, high activity of isocyanate, large cross-linking degree, fast cross-linking speed, too much amine and physical blowing agent cause low internal pressure of foam, foam elasticity can not be opened when the TDI index is too large will also lead to high rate of closed pore.
2
Shrinkage [gel speed is greater than foam speed].
High closed porosity, shrinkage when cooling.
Process conditions: low temperature, low material temperature.
Process formula: excessive silicone oil, excessive physical foaming agent, low TDI index.
3
Internal cracking
Process conditions: low temperature, high reaction center temperature.
Process formula: low TDI index, more tin, high early foaming strength.
High silicone oil activity, low dosage.
4
Top crack [unbalanced foaming gel speed
Process conditions: low temperature, low material temperature.
Process formula: insufficient amount of catalyst, low amount of amine, silicone oil quality is not good.
5
Bottom corner crack [too much amine dosage, too fast foaming speed
Surface macropore: excessive amount of physical foaming agent, poor quality of silicone oil and catalyst.
6
Poor low temperature performance of foam
Poor intrinsic quality of polyether polyol, in the same hydroxyl value, low functional degree, large unsaturation, low TDI index when the same tin dosage is used.
7
Poor aeration
Climate conditions: low temperature.
Raw material: high polyether polyol, high silicone oil activity.
Process formula: more tin or the same amount of tin, less water and amine content, high TDI index.
8
Poor inverse elasticity
Raw material: high activity of polyether polyol, small relative molecular mass, high activity of silicone oil.
Process formula: large amount of silicone oil, more tin, more water in the same amount of tin, high TDI index.
9
Poor tensile strength
Raw material: too much low molecular polyether polyol, low functionalities with hydroxyl value.
Process formula: less tin gel reaction is not good, in the same amount of tin, TDI index is high, less water cross-linking degree is low.
10
Smoke when foaming
Excess amine prompted by water and TDI reaction gives off a lot of heat, low boiling point material evaporation and smoke.
If not scorched heart, the smoke is mostly composed of TDI, low boiling point substances and monomeric naphthenes in polyether polyol.
11
Foam with white rib
The reaction speed of foaming and gelation is fast, and the transfer speed is slow in continuous foaming, and the dense layer is generated by local extrusion, resulting in the phenomenon of white tendon. The transfer speed should be increased in time, or the material temperature should be lowered and the amount of catalyst should be reduced.
12
Crispy foam
There is more water in the recipe, the generation of diurea has not been dissolved in silicone oil, poor tin catalyst, cross-linking reaction is not sufficient, small relative molecular mass polyether polyol content, the reaction temperature is too high, the ether bond breakage reduces the foam strength.
13
Foam density is lower than the set value
Foaming index is too large due to inaccurate measurement, high temperature and low gas pressure.
14
Foam has bottom skin, side skin, bottom cavitation
Tin polyamine less, slow foaming speed, fast gel speed, too low with temperature in continuous foaming
15
High elongation
Raw material: polyether polyol with high activity and small functionalities.
Process formula: low TDI index cross-linking deficiency, more tin, more silicone oil.
