Polyurethane dispersion, gas barrier coating material, and method for producing polyurethane dispersion

A method for producing a polyurethane dispersion containing a polyurethane resin, the method comprising:

• a prepolymer synthesis step of reacting a polyisocyanate component with an active hydrogen group-containing component containing a polyol compound and an active hydrogen group-containing compound containing an anionic group to synthesize an isocyanate group-terminated prepolymer,
• a neutralization step of, after the prepolymer synthesis step, neutralizing the anionic group by a primary neutralizing agent containing a monoamine compound having a tertiary amino group;
• a chain extension step of, after the neutralization step, reacting the isocyanate group-terminated prepolymer with a chain extender to obtain a polyurethane resin;
• and
• a substitution step of, after the chain extension step, substituting at least a part of the primary neutralizing agent with a secondary neutralizing agent containing a monoamine compound having a primary amino group or a secondary amino group.