**4. Summary**

The examination results presented in this paper are the answer for the search of fire‐safe polyurethanes with good application properties. The study proved that the modification of the premix for polyurethane foam production can give the foams the desired properties. The right selection of polyol materials, isocyanate and auxiliary compounds during the recipe creation is very important. Including the boron polyol in the foam recipe allowed obtain‐ ing new thermo‐insulating material with good physicomechanical properties. The research showed that the new compound, which was a derivative of N,N′‐di(methylenoxy‐3‐hydroxy‐ propyle)urea and boric acid, could be used as a polyol in the production of polyurethane materials, and simultaneously act as flame‐retardant agent. Complex study on the flamma‐ bility conducted using various methods helped assessing the behaviour of produced rigid polyurethane‐polyisocyanurate foams in case of fire. The research proved that the use of the new polyol, containing boron and nitrogen atoms, increased flame resistance. The efficiency of this resistance was mainly shown by the total value of released heat, prolongation of the time for steady combustion, lower amount of carbon oxide and dioxide emission, increase in the oxygen index and by the lower maximum burning temperature reached in shorter time in comparison to the reference foam.
