Rigid polyprene 9-2

Polyprene 9-2 is a rigid dual blown system based on expansion of the polyurethane by partly carbon dioxide from the water/isocyanate reaction and partly a physical blowing agent HCFC 141b. It is used in pipe insulation for district heating networks.
The system has good flowing properties which enable the foam to fill narrow cavities in 6-12 metre long pipes and adheres well both to the inner steel pipe and the outer high density polyethylene casing pipe.

Typical Component Properties

Units A-9-2 Polyol B – Polymeric MDI
OH number mg KOH/g 417 -
H2O content % 2.8 -
NCO content % - 30 – 32
Viscosity, 25°C cps 680 200
Specific Gravity, 25°C g/cm3 1.08 1.23

Recommended Process Conditions

Units Values
A-9-2 Polyol pbw 100
B – Polymeric MDI pbw 160
Components temperature °C 22 – 24
The temperature of the inner metal pipe °C 20 – 30

Typical Reaction Characteristics

Units Hand-mix*
Ratio Polyol /Iso 100:160
Cream time s 40 – 60
Gel time s 160 – 220
Rise time s 240 – 320
Free rise density kg/m3 32 – 38

*Data referred to laboratory tests made with Isocyanate component at 20°C and Polyol component at 20°C, hand-mixed with mechanical stirrer at 3000 rpm. Reported values vary depending on processing conditions.

Handling and Storage

The Iso component must be stored in liquid state. In case of crystallization it has to be melted heating the drum at 60-70°C for no more than 24 hours.

Units A-9-2 Polyol B – Polymeric MDI
Storage temperature °C 15 - 25 15 - 25
Shelf life months 6 6

Typical Polymer Properties

Pre-insulated pipes based on Polyprene 9-2 system and produced under conditions and recommendations mentioned in the previous section fulfill European norm EN 253, 5 requirements.

Units Typical value Requirement according to EN 253 (5)
Cell structure:
- average cell size;		 mm 0.2 <0.5
- closed cell content % 95 ≥88
Density:
- core density;		 kg/m3 66 ≥60
- overall density kg/m3 82 ≥80
Compressive strength (10%) MPa 0.45 ≥0.3
Water absorption at elevated temperature % vol. 3.5 ≤10

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