Patent ID: 8158741

Claim:
A polyurethane resin forming composition comprising a main agent (A) containing an isocyanate component and a curing agent (B) containing a polyol component; which contains, as the isocyanate component constituting the main agent (A), an isocyanate group-terminated prepolymer obtained by reacting an isocyanate group-containing compound (a1) with a polyfunctional polyether polyol (b1) which is obtained by the use of a compound having a functional group number of 8 as an initiator and wherein, in molecular weight distribution in terms of polypropylene polyol measured by gel permeation chromatography (GPC), a main peak having a peak top in the region of a molecular weight of 600 to 900 and accounting for 75% or more of total peak area is present and a ratio (Mw/Mn) of weight-average molecular weight (Mw) to number-average molecular weight (Mn) is 1.3 or less; and which contains, as the polyol component constituting the curing agent (B), a castor oil-modified polyol (b2) obtained from castor oil and/or a castor oil fatty acid and a trimethylolalkane.