| 摘要 |
A formulation for preparing a low density, full water blown polyurethane rigid foam includes an isocyanate component; an isocyanate-reactive component comprising from 30-50 wt % of a first polyether polyol having a functionality greater than 5 and an OH value from 350-550 mgKOH/g; from 5 to 25 wt % of a diol having an OH value from 100-300 mgKOH/g; and from 15 to 35 weight percent of a second polyether polyol having a functionality from 3 to 5; further including from 1.5 to 5 wt % of a catalyst selected from dimethylbenzylamine and/or 1,2-dimethyl-imidazole; from greater than 0 to 1 wt % of a trimerization catalyst selected from a glycine salt and/or tris(dimethyl aminomethyl) phenol; greater than 4.1 wt % water as a blowing agent; and any additional constituents selected such that the formulation, excluding the isocyanate component, totals 100 wt % and, the formulation absent the isocyanate component, has a dynamic viscosity from 540 to 864 mPa*s at 20° C. Processing under one-shot conditions can yield a rigid form having a molecular weight per crosslink ratio from 380 to 420. The formulation offers good processability, while the foam shows desirable dimensional stability and mechanical properties at unexpectedly low applied density. |
| 主权项 |
1. A composition comprising
a formulation for preparing a polyurethane rigid foam, the formulation comprising at least one isocyanate component; at least one isocyanate-reactive component comprising from 30 to 50 weight percent, based on the total weight of components 2 through 6, of a first polyether polyol, having a hydroxyl value from 350 to 550 milligrams of potassium hydroxide per gram of the polyol and a functionality greater than 5; from 5 to 25 weight percent, based on the total weight of the components 2 through 6, of at least one diol having a hydroxyl value from 100 to 300 milligrams potassium hydroxide per gram of the diol; and from 15 to 35 weight percent, based on the total weight of components 2 through 6, of at least a second polyether polyol, having a functionality from 3 to 5; from 1.5 to 5 weight percent, based on the total weight of components 2 through 6, of a catalyst selected from dimethylbenzylamine, 1,2-dimethyl-imidazole, and combinations thereof; from greater than 0 to 1 weight percent, based on the total weight of components 2 through 6, of a catalyst selected from a glycine salt, tris(dimethyl aminomethyl)phenol, and combinations thereof; greater than 4.1 wt %, based on the total weight of components 2 through 6, of water as a blowing agent; and, optionally, any additional constituent or constituents; provided that the weight of components 2 through 6 totals 100 weight percent and, absent the at least one isocyanate component (1), the formulation has a dynamic viscosity from 540 to 864 millipascals*seconds at 20 degrees Celsius; which, when reacted under one-shot conditions, forms a polyurethane rigid foam having a ratio of molecular weight to crosslink from 380 to 420. |
