| abstract |
The present invention provides a reaction mixture by mixing (a) an isocyanate, (b) a compound having a group reactive with isocyanate, (c) a blowing agent comprising water, (d) a catalyst, and (e) optionally further additives to form a reaction mixture, wherein A rigid polyurethane foam obtainable by applying a reaction mixture to a reinforcing material and curing the reaction mixture, wherein the isocyanate (a) has a viscosity at 25 ° C. of 500 mPas or less and has a group reactive to the isocyanate. Compound (b) has a polyetherol (b1) having a functionality of 4 or more and a viscosity at 25 ° C. of 10 kPamPas or less, a polyetherol (b2) having a function of 3.5 or less and a viscosity at 25 ° C. of 600 kPaPa or less. Rigid polyurethane, comprising a polyetherol (b3) having a viscosity at 25 ° C. of 2000 mPas or less, a chain extender (b4) comprising at least 30% secondary OH groups, and optionally a crosslinking agent (b5) It relates to a foam. The present invention relates to a process for the production of such rigid polyurethane foams and to the use of rigid polyurethane foams for the insulation of liquefied natural gas tanks. |