ISO-PUR® K750
Hydrophobic standard resin with lower potting viscosity
ISO-PUR® K750 is a slightly filled cold-curing 2-component polyurethane cast resin based on polyether and ester polyols, cured with polymeric aromatic diisocyanates. The potting compound has been tested according to VDE 0291 / part 2 including hydrophobic behaviour and hydrolysis resistance. Application up to 10 kV operating voltage (e.g. in cast resin cable joints, electronic components, transformers) is possible. The material does not contain any plasticisers and does not tend to become brittle. ISO-PUR® K750 is characterised by a low potting viscosity and shows good adhesion to metals and plastics. The hydrolysis resistance is excellent. ISO-PUR® K750 is RoHS compliant according to EU Directives 2011/65/EU (“RoHS”) and 2015/863/EU (“RoHS III”).
Technical data
Resin
Colour
Viscosity (25°C; rot.; 1 s-1)
Viscosity (25°C; rot.; 10 s-1)
Density (23°C)
Beige
Approx. 1200 mPas
Approx. 900 mPas
Approx. 1,07 g/cm³
Hardener
Colour
Viscosity (25°C; rot.; 1 s-1)
Viscosity (25°C; rot.; 10 s-1)
Density (23°C)
Brown
Approx. 130 mPas
Approx. 120 mPas
Approx. 1,23 g/cm³
Mixture
Mixing ratio resin : hardener
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Colour
Beige (other colours on request)
Density (23oC)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 1,11 g/cm³
Approx. 1,10 g/cm³
Approx. 1,10 g/cm³
Pot life (23°C) /
Gel time (23°C)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 54 min / Approx. 80 min
Approx. 55 min / Approx. 90 min
Approx. 56 min / Approx. 95 min
Mixed viscosity (25°C; rot.; 1 s-1)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 800 mPas
Approx. 850 mPas
Approx. 900 mPas
Mixed viscosity (25°C; rot.; 10 s-1)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 650 mPas
Approx. 700 mPas
Approx. 750 mPas
Cured product
under standard curing condition
(14 days 23°C / 50% relative humidity) unless otherwise stated
Hardness Shore A
(23°C; 14d RT 50% rel. h.) /
Hardness Shore A
(23°C; oven curing: 4hRT + 24h80°C)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
> 90 / > 90
Approx. 65 / Approx. 70
Approx. 58 / Approx. 60
Hardness Shore D
(23°C; 14d RT 50% rel. h.) /
Hardness Shore D
(23°C; oven curing: 4hRT + 24h80°C)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 53 / Approx. 53
Approx. 20 / Approx. 20
Approx. 15 / Approx. 15
Long-term temperature resistance /
Short-term temperature resistance
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 130°C / Approx. 200°C
Approx. 120°C / Approx. 180°C
Approx. 120°C / Approx. 160°C
Glass transition temperature (midset)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 24°C
Approx. -4°C
Approx. -13°C
Tensile strength (5A specimen)
(2 mm thickness; speed: 10 mm/min; 23°C)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 20 N/mm2
Approx. 2,9 N/mm2
Approx. 1,8 N/mm2
Elongation at break (5A specimen)
(2 mm thickness; speed: 10 mm/min; 23°C)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 100%
Approx. 95%
Approx. 90%
Tear resistance
(W-specimen; incision; speed: 10 mm/min; 23°C)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 30 N/mm
Approx. 2,5 N/mm
Approx. 2 N/mm
Dielectric strength
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
> 30 kV/mm
> 30 kV/mm
> 30 kV/mm
Dielectric loss factor tan δ (25°C; 50 Hz)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 0,007
Approx. 0,010
Approx. 0,008
Coefficient of thermal expansion
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 209×10-6 K-1
Approx. 215×10-6 K-1
Approx. 240×10-6 K-1
Water absorption after 28 days
in water immersion (23°C)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 0,70%
Approx. 2,50%
Approx. 7,50%
Water vapour permeability
(75% relative humidity; 23°C; 1 mm thickness)
2,2 : 1 parts by weight
3 : 1 parts by weight
3,5 : 1 parts by weight
Approx. 6,60×10-7 g/(Tag×mm2)
Approx. 7,00×10-7 g/(Tag×mm2)
Approx. 7,20×10-7 g/(Tag×mm2)
Storage and transport
Store in a dry and airtight, closed container at 10 – 35°C. Can be stored for at least 12 months in original sealed containers under the above conditions. Short-term deviations during transport and storage are acceptable.
Cleaning
To ensure good adhesion of the cast resin the customer should individually test the suitability of the involved surfaces. Possible pre-treat-ments like cleaning, activation processes (plasma process) etc. should also be taken into account. The contact surfaces should be free of dirt such as dust, grease or water. For cleaning we recommend ISO-RC® Degreaser for wipe degreasing or ISO-RC® Flux-Off + ISO-RC® Spraywash for spray degreasing (available in 400 ml spray cans).
Processing
Stir up the resin container thoroughly before use to remove any possible sedimentation. Weigh the resin and hardener in the desired mixing ratio and mix for 1 – 3 minutes (depending on mixed quantity and processing time). Apply suitable mixing speed in order to ensure complete homogeneous mixing without introducing too many air bubbles into the reaction mass. The ideal processing temperature is 20 – 25°C. In general, curing is delayed at lower temperatures and accelerated at higher temperatures. When using a double chamber bag, empty the corners well and knead for 3 minutes. Before casting, a homogeneous mass, free of streaks, must be obtained. Pour immediately afterwards and do not scrape the mixing vessel. Air bubbles that have been stirred in, can be removed before the end of the pot-life by evacuating the material or carefully fanning the surface with a hot air gun. Machine casting is also possible.
The EC safety data sheet provides information on safety-relevant product properties.
Hardener component (containing diisocyanate): As of August 24, 2023, appropriate training must be provided before industrial or commercial use.