Prepolymer composition, polyurethane resin, elastic molded article, and method for producing prepolymer composition

A polyurethane resin comprising:

• a reaction product of a prepolymer composition and a chain extender, wherein
• the prepolymer composition contains an isocyanate group-terminated prepolymer;
• the isocyanate group-terminated prepolymer contains a reaction product of a polyisocyanate component and a polyol component;
• the polyisocyanate component contains a diphenylmethane diisocyanate;
• the polyol component contains a high molecular weight polyol and a low molecular weight polyol;
• the high molecular weight polyol contains a high molecular weight polyether polyol having a number average molecular weight of above 700 and below 1300;
• the low molecular weight polyol contains a low molecular weight polyether polyol having the number average molecular weight of above 150 and below 350;
• the isocyanate group concentration of the prepolymer composition is 6.0% by mass or more and 8.0% by mass or less;
• and
• a content ratio of the low molecular weight polyol is above 0.05 mol/kg and below 0.40 mol/kg with respect to the total amount of the polyisocyanate component, the high molecular weight polyol, and the low molecular weight polyol.

A method for producing a prepolymer composition;

• the prepolymer composition containing an isocyanate group-terminated prepolymer, comprising:
• a step of preparing a polyisocyanate component and a polyol component and
• a step of reacting the polyisocyanate component with the polyol component to synthesize the isocyanate group-terminated prepolymer, wherein
• the polyisocyanate component contains a diphenylmethane diisocyanate;
• the polyol component contains a high molecular weight polyol and a low molecular weight polyol;
• the high molecular weight polyol contains a high molecular weight polyether polyol having a number average molecular weight of above 700 and below 1300;
• the low molecular weight polyol contains a low molecular weight polyether polyol having the number average molecular weight of above 150 and below 350;
• the isocyanate group concentration of the prepolymer composition is 6.0% by mass or more and 8.0% by mass or less;
• and
• a content ratio of the low molecular weight polyol is above 0.05 mol/kg and below 0.40 mol/kg with respect to the total amount of the polyisocyanate component, the high molecular weight polyol, and the low molecular weight polyol.