Moisture curable hot melt urethane composition, method for producing cured foam of same, synthetic leather and method for producing synthetic leather

A method for producing a foamed and cured product of a moisture-curable hot melt urethane composition, which comprises

• heat-melting a hot melt urethane prepolymer (A) having an isocyanate group in a content of 1.1 to 3.3% by mass,
• mixing a foaming agent composition (B) containing N,N′-dinitrosopentamethylenetetramine (b1), urea (b2), and a polyol (b3) therewith,
• applying the resultant mixture to a substrate, and
• performing a heating treatment at a temperature equal to or higher than the heat-melting temperature of the hot melt urethane prepolymer (A) to thereby cause foaming and curing,
• wherein the polyol (b3) is a polymerization product of polyoxypropylene triol and/or glycerin and propylene oxide having a number average molecular weight of 500 to 10,000, and
• wherein the mass ratio [(b1)+(b2)/(b3)] of the total mass of the N,N′-dinitrosopentamethylenetetramine (b1) and urea (b2) to the polyol (b3) is a range from 10/90 to 70/30.

A method for producing a synthetic leather, which comprises heat-melting a hot melt urethane prepolymer (A) having an isocyanate group in a content of 1.1 to 3.3% by mass,

• mixing a foaming agent composition (B) containing N,N′-dinitrosopentamethylenetetramine (b1), urea (b2), and a polyol (b3) therewith to give a moisture-curable hot melt urethane composition,
• applying the moisture-curable hot melt composition onto a surface skin layer (iii) formed on a release paper,
• performing a heating treatment at a temperature equal to or higher than the heat-melting temperature of the hot melt urethane prepolymer (A) to form an intermediate layer (ii), and
• subsequently attaching a base fabric (i) onto the intermediate layer (ii),
• wherein the polyol (b3) is a polymerization product of polyoxypropylene triol and/or glycerin and propylene oxide having a number average molecular weight of 500 to 10,000, and
• wherein the mass ratio [(b1)+(b2)/(b3)] of the total mass of the N,N′-dinitrosopentamethylenetetramine (b1) and urea (b2) to the polyol (b3) is a range from 10/90 to 70/30.