Rigid polyurethane foam made with a hydrocarbon blowing agent and 1,1,1,4,4,4-hexafluorobut-2-ene

A method of manufacturing a thermally insulated cabinet, comprising

• A) positioning an outer shell member and an inner liner member so as to define a cavity therebetween;
• B) introducing the reaction system into the cavity;
• and
• C) curing the reaction system such that it expands and reacts to produce a polyurethane foam that fills the cavity and adheres to the outer shell member and to the inner liner member, wherein the reaction system comprises:
• a) at least one polyisocyanate;
• b) at least one polyol;
• c) at least one urethane catalyst;
• d) at least one foam-stabilizing surfactant;
• e) 0 to 3 weight-percent water, based on the combined weights of components b), c), d) and e);
• f) 2 to 4 parts by weight, per 100 parts by weight of components b), c), d) and e), of 1,1,1,4,4,4-hexaflurobut-2-ene;
• and
• g) 12 to 20 parts by weight, per 100 parts by weight of components b), c), d) and e), of one or more hydrocarbons having 4 to 6 carbon atoms,
• wherein the reaction system contains from 5 weight percent to 30 weight percent of an alkoxylated o-toluene diamine polyol, based on the combined weights of components b), c), d) and e), and
• a subatmospheric pressure of 700 to 950 millibars absolute is maintained in the cavity during at least step B).